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Sample records for antimicrobial phagocytosis progress

  1. Mechanisms of innate immunity: cytoplasmic granules of polymorphonuclear neutrophilic granulocytes, antimicrobial action, translocation, role, and fate in antimicrobial phagocytosis. Progress report, March 1976--June 30, 1977

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    Spitznagel, J.K.

    1977-01-01

    Progress is reported on the following research projects: characterization of the III f granules of human neutrophil polymorphonuclear granulocytes (PMN); studies on glycosidases using methylumbelliferyl derivatives of the sugars with spectrofluorometry; distribution of proteinases and cationic proteins in human PMN; comparison of granules of eosinophils with those of other PMN; identification of a cyanide-resistant NADPH oxidase in PMN; subcellular localization of superoxide dismutase in PMN; oxygen-independent antimicrobial activities of each granule class; the phagocytic and intraleukocytic killing capacity of PMN deprived of their specific granules with phorbol myristate acetate; and studies on the PMN of an infant with the Chediak Higashi syndrome. (HLW)

  2. [The phagocytosis of polymorphonuclear neutrophilic granulocytes in progressive periodontitis].

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    Konopka, T; Zietek, M

    1995-01-01

    The aim of this paper was the evaluation of the phagocytic activity of neutrophils in blood and in gingival pocket fluid in patients suffering from rapidly progressive periodontitis (RPP) and postjuvenile periodontitis (PJP). Prior to periodontal treatment the authors evaluated the capacity to phagocytose latex particles of peripheral blood neutrophils from 21 patients with RPP, 51 with PJP and 59 healthy subjects (control group) as well as the phagocytic activity of neutrophils in pocket fluid from 21 patients with RPP, 14 with PJP and from 20 healthy subjects. This phagocytic activity was significantly lower in all examined groups in comparison with the control group. A similar evaluation executed 3 months after treatment revealed normal phagocytosis of blood neutrophils from patients with RPP. In patients receiving complementary pharmacotherapy (spiramycine combined with metronidazol), a better improvement of phagocytosis was noted, than that observed in patients treated only surgically.

  3. [Progress in researches on synthetic antimicrobial macromolecular polymers].

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    Wei, Gang; Yang, Lihua; Chu, Liangyin

    2010-08-01

    Broad-spectrum antimicrobial peptides provide a new way to address the urgent growing problem of bacterial resistance. However, the limited natural resources and the high cost of extraction and purification of natural antimicrobial peptides can not meet the requirements of clinical application. In order to solve this problem, researchers have utilized two basic common structural features (amphiphilic and cationic) for designing and preparing synthetic antimicrobial macromolecular polymers. During the last decade, several kinds of amphiphilic polymers, including arylamide oligomers, phenylene ethynylenes, polymethacrylates, polynorbornenes as well as nylon-3 polymers have been synthesized. In this paper, the structures, antibacterial activities and selectivities of these polymers are reviewed, and the effects of molecular size, polarity and ratio of hydrophobic groups, positive charge density on antibacterial activity and selectivity are also summarized.

  4. Antimicrobial activity of carvacrol: current progress and future prospectives.

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    Nostro, Antonia; Papalia, Teresa

    2012-04-01

    During the last few years the scientific community has shown a considerable interest in the study of plant materials as sources of new compounds to be processed into antimicrobial agents. In this context, carvacrol, a monoterpenic phenol, has emerged for its wide spectrum activity extended to food spoilage or pathogenic fungi, yeast and bacteria as well as human, animal and plant pathogenic microorganisms including drug-resistant and biofilm forming microorganisms. The antibacterial activity of carvacrol has been attributed to its considerable effects on the structural and functional properties of cytoplasmatic membrane. The data reported in this review provide an overview of the published literature regarding the antimicrobial properties of carvacrol and the recent patents claimed in order to highlight its future applications as a new antimicrobial agent. These could concern either the natural preservation in the cosmetic and food industries or an alternative which supports the conventional antimicrobial protocols. Interestingly, carvacrol alone or associated with one or more synergistic products could be incorporated in different formulations for biomedical and food packaging applications. However, more detailed safety investigations and in vivo studies should be carried out so that this molecule could be used in the future.

  5. Microglial Amyloid-β1-40 Phagocytosis Dysfunction Is Caused by High-Mobility Group Box Protein-1: Implications for the Pathological Progression of Alzheimer’s Disease

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    Kazuyuki Takata

    2012-01-01

    Full Text Available In Alzheimer disease (AD patient brains, the accumulation of amyloid-β (Aβ peptides is associated with activated microglia. Aβ is derived from the amyloid precursor protein; two major forms of Aβ, that is, Aβ1-40 (Aβ40 and Aβ1-42 (Aβ42, exist. We previously reported that rat microglia phagocytose Aβ42, and high mobility group box protein 1 (HMGB1, a chromosomal protein, inhibits phagocytosis. In the present study, we investigated the effects of exogenous HMGB1 on rat microglial Aβ40 phagocytosis. In the presence of exogenous HMGB1, Aβ40 markedly increased in microglial cytoplasm, and the reduction of extracellular Aβ40 was inhibited. During this period, HMGB1 was colocalized with Aβ40 in the cytoplasm. Furthermore, exogenous HMGB1 inhibited the degradation of Aβ40 induced by the rat microglial cytosolic fraction. Thus, extracellular HMGB1 may internalize with Aβ40 in the microglial cytoplasm and inhibit Aβ40 degradation by microglia. This may subsequently delay Aβ40 clearance. We further confirmed that in AD brains, the parts of senile plaques surrounded by activated microglia are composed of Aβ40, and extracellular HMGB1 is deposited on these plaques. Taken together, microglial Aβ phagocytosis dysfunction may be caused by HMGB1 that accumulates extracellularly on Aβ plaques, and it may be critically involved in the pathological progression of AD.

  6. Neutrophil-mediated phagocytosis of Staphylococcus aureus

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    Jos A.G. Van Strijp

    2014-09-01

    Full Text Available For invading staphylococci, phagocytosis an killing bij human neutrophils is the biggest threat. Neutrophils are the only cells that can effectively kill staphylococci by engulfment and subsequent bombardment with proteases, amidases, antimicrobial peptides and proteins in concert with reactive oxygen species that are generated during the metabolic burst.Both complement and antibodies are crucial for effective uptake and neutrophil activation. S. aureus is not an innocent bystander in this process. It actively secretes several proteins to impair every single step in this process from receptor modulation, to complement inhibition to neutrophil lysis to protease, antimicrobial peptide inhibition and resistance to reactive oxygen species. For the design of future novel antimicrobial strategies: therapeutic antibodies, vaccines, novel antibiotics, all this should be taken into account. Still the best way to treat diseases is to help to enhance the natural defence mechanism that are already in place.

  7. Small molecule phagocytosis inhibitors for immune cytopenias.

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    Neschadim, Anton; Kotra, Lakshmi P; Branch, Donald R

    2016-08-01

    Immune cytopenias are conditions characterized by low blood cell counts, such as platelets in immune thrombocytopenia (ITP) and red blood cells in autoimmune hemolytic anemia (AIHA). Chronic ITP affects approximately 4 in 100,000 adults annually while AIHA is much less common. Extravascular phagocytosis and massive destruction of autoantibody-opsonized blood cells by macrophages in the spleen and liver are the hallmark of these conditions. Current treatment modalities for ITP and AIHA include the first-line use of corticosteroids; whereas, IVIg shows efficacy in ITP but not AIHA. One main mechanism of action by which IVIg treatment leads to the reduction in platelet destruction rates in ITP is thought to involve Fcγ receptor (FcγR) blockade, ultimately leading to the inhibition of extravascular platelet phagocytosis. IVIg, which is manufactured from the human plasma of thousands of donors, is a limited resource, and alternative treatments, particularly those based on bioavailable small molecules, are needed. In this review, we overview the pathophysiology of ITP, the role of Fcγ receptors, and the mechanisms of action of IVIg in treating ITP, and outline the efforts and progress towards developing novel, first-in-class inhibitors of phagocytosis as synthetic, small molecule substitutes for IVIg in ITP and other conditions where the pathobiology of the disease involves phagocytosis.

  8. Stimulation of phagocytosis by sulforaphane

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    Suganuma, Hiroyuki, E-mail: hsuganu1@jhmi.edu [Lewis B. and Dorothy Cullman Cancer Chemoprotection Center, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205 (United States); Fahey, Jed W., E-mail: jfahey@jhmi.edu [Lewis B. and Dorothy Cullman Cancer Chemoprotection Center, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205 (United States); Bryan, Kelley E., E-mail: kbryanm1@jhmi.edu [Lewis B. and Dorothy Cullman Cancer Chemoprotection Center, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205 (United States); Healy, Zachary R., E-mail: zhealy1@jhmi.edu [Lewis B. and Dorothy Cullman Cancer Chemoprotection Center, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205 (United States); Talalay, Paul, E-mail: ptalalay@jhmi.edu [Lewis B. and Dorothy Cullman Cancer Chemoprotection Center, Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205 (United States)

    2011-02-04

    Research highlights: {yields} Sulforaphane stimulates the phagocytosis of RAW 264.7 macrophages under conditions of serum deprivation. {yields} This effect does not require Nrf2-dependent induction of phase 2 genes. {yields} Inactivation of macrophage migration inhibitory factor (MIF) by sulforaphane may be involved in stimulation of phagocytosis by sulforaphane. -- Abstract: Sulforaphane, a major isothiocyanate derived from cruciferous vegetables, protects living systems against electrophile toxicity, oxidative stress, inflammation, and radiation. A major protective mechanism is the induction of a network of endogenous cytoprotective (phase 2) genes that are regulated by transcription factor Nrf2. To obtain a more detailed understanding of the anti-inflammatory and immunomodulatory effects of sulforaphane, we evaluated its effect on the phagocytosis activity of RAW 264.7 murine macrophage-like cells by measuring the uptake of 2-{mu}m diameter polystyrene beads. Sulforaphane raised the phagocytosis activity of RAW 264.7 cells but only in the absence or presence of low concentrations (1%) of fetal bovine serum. Higher serum concentrations depressed phagocytosis and abolished its stimulation by sulforaphane. This stimulation did not depend on the induction of Nrf2-regulated genes since it occurred in peritoneal macrophages of nrf2{sup -/-} mice. Moreover, a potent triterpenoid inducer of Nrf2-dependent genes did not stimulate phagocytosis, whereas sulforaphane and another isothiocyanate (benzyl isothiocyanate) had comparable inducer potencies. It has been shown recently that sulforaphane is a potent and direct inactivator of macrophage migration inhibitory factor (MIF), an inflammatory cytokine. Moreover, the addition of recombinant MIF to RAW 264.7 cells attenuated phagocytosis, but sulforaphane-inactivated MIF did not affect phagocytosis. The inactivation of MIF may therefore be involved in the phagocytosis-enhancing activity of sulforaphane.

  9. Addressing healthcare-associated infections and antimicrobial resistance from an organizational perspective: progress and challenges.

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    Murray, Eleanor; Holmes, Alison

    2012-07-01

    This paper explores the progress and challenges associated with the application of organizational factors and approaches to infection prevention and control (IPC) and antibiotic stewardship (AS) in England, many of which have been considered and supported by the Advisory Committee on Antimicrobial Resistance and Healthcare-associated Infections (ARHAI). An organizational perspective is described and the wider macro context and socio-political forces that shape an organizational approach are considered. Factors that drive organizational change in IPC and AS are discussed. The tensions, constraints and dilemmas that can occur are identified and outstanding challenges are debated. Some recommendations for the future direction of IPC and AS organizationally focused strategies and research are proposed.

  10. 抗菌肽histatherin研究进展%Research Progress of Antimicrobial Peptide Histatherin

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    高帅; 鞠志花; 宿烽; 王长法

    2011-01-01

    抗菌肽产于机体组织、具有广谱抗菌活性和独特抗菌的机制.对抗菌肽的研究有助于开发抗菌肽药物、进行动物抗性育种和培育抗菌肽转基因动物.论文对一种新的牛抗菌肽histatherin的研究进展进行概述.%As the drug-resistance and challenge to food safety caused by the abuse of antibiotics is becoming serious , more and more attentions have been attracted to the antimicrobial peptides, which has characteristics of antimicrobial mechanism and wide antimicrobial spectrum. The research on antimicrobial peptides will contribute to antimicrobial peptides drug development, resistive breeding, and transgenic animal breeding. This article introduced the studies about a new bovine antimicrobial peptide-histatherin.

  11. Stimulation of phagocytosis by sulforaphane

    OpenAIRE

    Suganuma, Hiroyuki; Fahey, Jed W.; Bryan, Kelley E.; Healy, Zachary R.; Talalay, Paul

    2011-01-01

    Sulforaphane, a major isothiocyanate derived from cruciferous vegetables, protects living systems against electrophile toxicity, oxidative stress, inflammation, and radiation. A major protective mechanism is the induction of a network of endogenous cytoprotective (phase 2) genes that are regulated by transcription factor Nrf2. To obtain more detailed understanding of the anti-inflammatory and immunomodulatory effects of sulforaphane, we evaluated its effect on the phagocytosis activity of RAW...

  12. Antimicrobial activity of cationic antimicrobial peptides against gram-positives: Current progress made in understanding the mode of action and the response of bacteria

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    Soraya Omardien

    2016-10-01

    Full Text Available Antimicrobial peptides (AMPs have been proposed as a novel class of antimicrobials that could aid the fight against antibiotic resistant bacteria. The mode of action of AMPs as acting on the bacterial cytoplasmic membrane has often been presented as an enigma and there are doubts whether the membrane is the sole target of AMPs. Progress has been made in clarifying the possible targets of these peptides, which is reported in this review with as focus gram-positive vegetative cells and spores. Numerical estimates are discussed to evaluate the possibility that targets, other than the membrane, could play a role in susceptibility to AMPs. Concerns about possible resistance that bacteria might develop to AMPs are addressed. Proteomics, transcriptomics and other molecular techniques are reviewed in the context of explaining the response of bacteria to the presence of AMPs and to predict what resistance strategies might be. Emergent mechanisms are cell envelope stress responses as well as enzymes able to degrade and/or specifically bind (and thus inactivate AMPs. Further studies are needed to address the broadness of the AMP resistance and stress responses observed.

  13. Antimicrobial Activity of Cationic Antimicrobial Peptides against Gram-Positives: Current Progress Made in Understanding the Mode of Action and the Response of Bacteria

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    Omardien, Soraya; Brul, Stanley; Zaat, Sebastian A. J.

    2016-01-01

    Antimicrobial peptides (AMPs) have been proposed as a novel class of antimicrobials that could aid the fight against antibiotic resistant bacteria. The mode of action of AMPs as acting on the bacterial cytoplasmic membrane has often been presented as an enigma and there are doubts whether the membrane is the sole target of AMPs. Progress has been made in clarifying the possible targets of these peptides, which is reported in this review with as focus gram-positive vegetative cells and spores. Numerical estimates are discussed to evaluate the possibility that targets, other than the membrane, could play a role in susceptibility to AMPs. Concerns about possible resistance that bacteria might develop to AMPs are addressed. Proteomics, transcriptomics, and other molecular techniques are reviewed in the context of explaining the response of bacteria to the presence of AMPs and to predict what resistance strategies might be. Emergent mechanisms are cell envelope stress responses as well as enzymes able to degrade and/or specifically bind (and thus inactivate) AMPs. Further studies are needed to address the broadness of the AMP resistance and stress responses observed.

  14. Phagocytosis and Killing of Staphylococcus aureus by Human Neutrophils

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    Lu, Thea; Porter, Adeline R.; Kennedy, Adam D.; Kobayashi, Scott D.; Frank R DeLeo

    2014-01-01

    Neutrophils are essential for host defense against Staphylococcus aureus infections. Although significant progress has been made, our understanding of neutrophil interactions with S. aureus remains incomplete. To provide a more comprehensive view of this process, we investigated phagocytosis and killing of S. aureus by human neutrophils using varied assay conditions in vitro. A greater percentage of bacteria were internalized by adherent neutrophils compared to those in suspension, and unexpe...

  15. Teaching Phagocytosis Using Flow Cytometry

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    John Boothby

    2009-12-01

    Full Text Available Investigative microbiology on protists in a basic teaching laboratory environment is limited by student skill level, ease of microbial culture and manipulation, instrumentation, and time. The flow cytometer is gaining use as a mainstream instrument in research and clinical laboratories, but has had minimal application in teaching laboratories. Although the cost of a flow cytometer is currently prohibitive for many microbiology teaching environments and the number of trained instructors and teaching materials is limited, in many ways the flow cytometer is an ideal instrument for teaching basic microbiology. We report here on a laboratory module to study phagocytosis in Tetrahymena sp. using flow cytometry in a basic microbiology teaching laboratory. Students and instructors found the flow cytometry data analysis program, Paint-A-GatePRO-TM, to be very intuitive and easy to learn within a short period of time. Assessment of student learning about Tetrahymena sp., phagocytosis, flow cytometry, and investigative microbiology using an inquiry-based format demonstrated an overall positive response from students.

  16. 抗菌肽的研究及进展%Research Progress in Antimicrobial Peptides

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    姚佳; 周玉玲; 张贞; 王宁

    2012-01-01

    Antimicrobial peptides,a kind of small peptides with biological activity, widely existing in various organisms. Antimicrobial peptides are an important component of the innate immune system of organisms. Many findings suggest that antimicrobial peptides not only have the capabilities of antibacterial and inhibition, but also anti-virus and anti-tumor. Here is to summarize the activity, mechanism of action and method of artificial preparation of antimicrobial peptides, and briefly introduce its application and development in each field.%抗菌肽是一种广泛存在于各类生物体内具有生物活性的小分子多肽,它是构成机体天然免疫系统的重要组成部分.各种研究结果表示,抗菌肽不但有抗菌抑菌功能,同时还有抗病毒、抗肿瘤的功效.现对抗菌肽在抑菌活性、作用机制以及人工制备方法等进行总结,并简要介绍目前抗菌肽在各个领域的应用情况及发展进程.

  17. TROPLE-LUX-B: Phagocytosis in mussel hemocytes

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    Hansen, P. D.; Unruh, E.

    2005-08-01

    The TRIPLELUX-B Experiment contributes to risk assessment concerning immunotoxicity under space flight conditions. The assay system of the TRIPLELUX-B Experiment will be performed with a well defined quantification and evaluation of the immune function phagocytosis. The indicator cells are the hemocytes of blue mussels (Mytilus edulis) and oysters (Crassostrea gigas). The signals of the immuno cellular responses are translated into luminescence as a rapid optical reporter system. The results expected will allow to conclude wether the observed responses are caused by microgravity and/or radiation. The immune system of invertebrates has not been studied so far in space.The choice of the phagocytes from invertebrates is justified by the claim to study the universal validity of innate immune responses. The components of the phagocytosis test system for the BIOLAB are now established under terrestrial conditions. The next step for adaptation to the BIOLAB conditions and hardware is in progress.

  18. Role of phospholipids in endocytosis, phagocytosis, and macropinocytosis.

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    Bohdanowicz, Michal; Grinstein, Sergio

    2013-01-01

    Endocytosis, phagocytosis, and macropinocytosis are fundamental processes that enable cells to sample their environment, eliminate pathogens and apoptotic bodies, and regulate the expression of surface components. While a great deal of effort has been devoted over many years to understanding the proteins involved in these processes, the important contribution of phospholipids has only recently been appreciated. This review is an attempt to collate and analyze the rapidly emerging evidence documenting the role of phospholipids in clathrin-mediated endocytosis, phagocytosis, and macropinocytosis. A primer on phospholipid biosynthesis, catabolism, subcellular distribution, and transport is presented initially, for reference, together with general considerations of the effects of phospholipids on membrane curvature and charge. This is followed by a detailed analysis of the critical functions of phospholipids in the internalization processes and in the maturation of the resulting vesicles and vacuoles as they progress along the endo-lysosomal pathway.

  19. Recent progress of antimicrobial wound dressings%抗菌敷料研究进展

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    周英; 许零

    2012-01-01

    感染是烧创伤护理领域最为普遍的并发症之一,使用适宜的局部抗菌敷料可以充分降低伤口的感染,同时全面促进伤口痊愈.本文从敷料载体分类的角度出发,综述了纤维、水凝胶、海绵、薄膜型抗菌敷料研究的最新进展,分析了目前抗菌敷料的优缺点,并对未来的发展趋势进行了展望.%Infection is one of the most common complications in the wound care field. Using appropriate antimicrobial wound dressings can reduce infection and promote wound healing. Different forms of antimicrobial wound dressings, such as fiber, hydrogel, sponge and film, were summarized. The main advantages and disadvantges of these dressings an presented. Finally, the development trend of antimicrobial wound dressings in the future is discussed.

  20. Phagocytosis and killing of Staphylococcus aureus by human neutrophils.

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    Lu, Thea; Porter, Adeline R; Kennedy, Adam D; Kobayashi, Scott D; DeLeo, Frank R

    2014-01-01

    Neutrophils are essential for host defense against Staphylococcus aureus infections. Although significant progress has been made, our understanding of neutrophil interactions with S. aureus remains incomplete. To provide a more comprehensive view of this process, we investigated phagocytosis and killing of S. aureus by human neutrophils using varied assay conditions in vitro. A greater percentage of bacteria were internalized by adherent neutrophils compared to those in suspension, and, unexpectedly, uptake of S. aureus by adherent neutrophils occurred efficiently in the absence of opsonins. An antibody specific for S. aureus promoted uptake of unopsonized bacteria in suspension, but had little or no capacity to enhance phagocytosis of S. aureus opsonized with normal human serum or by adherent neutrophils. Collectively, these results indicate that assay conditions can have a significant influence on the phagocytosis and killing of S. aureus by neutrophils. More importantly, the results suggest a vaccine approach directed to enhance opsonophagocytosis alone is not sufficient to promote increased killing of S. aureus by human neutrophils. With the emergence and reemergence of antibiotic-resistant microorganisms, establishing parameters that are optimal for studying neutrophil-S. aureus interactions will pave the way towards developing immune-directed strategies for anti-staphylococcal therapies.

  1. Ameobal pathogen mimivirus infects macrophages through phagocytosis.

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    Eric Ghigo

    2008-06-01

    Full Text Available Mimivirus, or Acanthamoeba polyphaga mimivirus (APMV, a giant double-stranded DNA virus that grows in amoeba, was identified for the first time in 2003. Entry by phagocytosis within amoeba has been suggested but not demonstrated. We demonstrate here that APMV was internalized by macrophages but not by non-phagocytic cells, leading to productive APMV replication. Clathrin- and caveolin-mediated endocytosis pathways, as well as degradative endosome-mediated endocytosis, were not used by APMV to invade macrophages. Ultrastructural analysis showed that protrusions were formed around the entering virus, suggesting that macropinocytosis or phagocytosis was involved in APMV entry. Reorganization of the actin cytoskeleton and activation of phosphatidylinositol 3-kinases were required for APMV entry. Blocking macropinocytosis and the lack of APMV colocalization with rabankyrin-5 showed that macropinocytosis was not involved in viral entry. Overexpression of a dominant-negative form of dynamin-II, a regulator of phagocytosis, inhibited APMV entry. Altogether, our data demonstrated that APMV enters macrophages through phagocytosis, a new pathway for virus entry in cells. This reinforces the paradigm that intra-amoebal pathogens have the potential to infect macrophages.

  2. The origins of phagocytosis and eukaryogenesis.

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    Yutin, Natalya; Wolf, Maxim Y; Wolf, Yuri I; Koonin, Eugene V

    2009-02-26

    Phagocytosis, that is, engulfment of large particles by eukaryotic cells, is found in diverse organisms and is often thought to be central to the very origin of the eukaryotic cell, in particular, for the acquisition of bacterial endosymbionts including the ancestor of the mitochondrion. Comparisons of the sets of proteins implicated in phagocytosis in different eukaryotes reveal extreme diversity, with very few highly conserved components that typically do not possess readily identifiable prokaryotic homologs. Nevertheless, phylogenetic analysis of those proteins for which such homologs do exist yields clues to the possible origin of phagocytosis. The central finding is that a subset of archaea encode actins that are not only monophyletic with eukaryotic actins but also share unique structural features with actin-related proteins (Arp) 2 and 3. All phagocytic processes are strictly dependent on remodeling of the actin cytoskeleton and the formation of branched filaments for which Arp2/3 are responsible. The presence of common structural features in Arp2/3 and the archaeal actins suggests that the common ancestors of the archaeal and eukaryotic actins were capable of forming branched filaments, like modern Arp2/3. The Rho family GTPases that are ubiquitous regulators of phagocytosis in eukaryotes appear to be of bacterial origin, so assuming that the host of the mitochondrial endosymbiont was an archaeon, the genes for these GTPases come via horizontal gene transfer from the endosymbiont or in an earlier event. The present findings suggest a hypothetical scenario of eukaryogenesis under which the archaeal ancestor of eukaryotes had no cell wall (like modern Thermoplasma) but had an actin-based cytoskeleton including branched actin filaments that allowed this organism to produce actin-supported membrane protrusions. These protrusions would facilitate accidental, occasional engulfment of bacteria, one of which eventually became the mitochondrion. The acquisition of

  3. A Novel Alpha Kinase EhAK1 Phosphorylates Actin and Regulates Phagocytosis in Entamoeba histolytica

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    Mansuri, M. Shahid; Bhattacharya, Sudha; Bhattacharya, Alok

    2014-01-01

    Phagocytosis plays a key role in nutrient uptake and virulence of the protist parasite Entamoeba histolytica. Phagosomes have been characterized by proteomics, and their maturation in the cells has been studied. However, there is so far not much understanding about initiation of phagocytosis and formation of phagosomes at the molecular level. Our group has been studying initiation of phagocytosis and formation of phagosomes in E. histolytica, and have described some of the molecules that play key roles in the process. Here we show the involvement of EhAK1, an alpha kinase and a SH3 domain containing protein in the pathway that leads to formation of phagosomes using red blood cell as ligand particle. A number of approaches, such as proteomics, biochemical, confocal imaging using specific antibodies or GFP tagged molecules, expression down regulation by antisense RNA, over expression of wild type and mutant proteins, were used to understand the role of EhAK1 in phagocytosis. EhAK1 was found in the phagocytic cups during the progression of cups, until closure of phagosomes, but not in the phagosomes themselves. It is recruited to the phagosomes through interaction with the calcium binding protein EhCaBP1. A reduction in phagocytosis was observed when EhAK1 was down regulated by antisense RNA, or by over expression of the kinase dead mutant. G-actin was identified as one of the major substrates of EhAK1. Phosphorylated actin preferentially accumulated at the phagocytic cups and over expression of a phosphorylation defective actin led to defects in phagocytosis. In conclusion, we describe an important component of the pathway that is initiated on attachment of red blood cells to E. histolytica cells. The main function of EhAK1 is to couple signalling events initiated after accumulation of EhC2PK to actin dynamics. PMID:25299184

  4. The origins of phagocytosis and eukaryogenesis

    Directory of Open Access Journals (Sweden)

    Wolf Yuri I

    2009-02-01

    Full Text Available Abstract Background Phagocytosis, that is, engulfment of large particles by eukaryotic cells, is found in diverse organisms and is often thought to be central to the very origin of the eukaryotic cell, in particular, for the acquisition of bacterial endosymbionts including the ancestor of the mitochondrion. Results Comparisons of the sets of proteins implicated in phagocytosis in different eukaryotes reveal extreme diversity, with very few highly conserved components that typically do not possess readily identifiable prokaryotic homologs. Nevertheless, phylogenetic analysis of those proteins for which such homologs do exist yields clues to the possible origin of phagocytosis. The central finding is that a subset of archaea encode actins that are not only monophyletic with eukaryotic actins but also share unique structural features with actin-related proteins (Arp 2 and 3. All phagocytic processes are strictly dependent on remodeling of the actin cytoskeleton and the formation of branched filaments for which Arp2/3 are responsible. The presence of common structural features in Arp2/3 and the archaeal actins suggests that the common ancestors of the archaeal and eukaryotic actins were capable of forming branched filaments, like modern Arp2/3. The Rho family GTPases that are ubiquitous regulators of phagocytosis in eukaryotes appear to be of bacterial origin, so assuming that the host of the mitochondrial endosymbiont was an archaeon, the genes for these GTPases come via horizontal gene transfer from the endosymbiont or in an earlier event. Conclusion The present findings suggest a hypothetical scenario of eukaryogenesis under which the archaeal ancestor of eukaryotes had no cell wall (like modern Thermoplasma but had an actin-based cytoskeleton including branched actin filaments that allowed this organism to produce actin-supported membrane protrusions. These protrusions would facilitate accidental, occasional engulfment of bacteria, one of which

  5. Research Progress of Antimicrobial Peptides from Aquatic Low-value Fish%水产低值鱼抗菌肽研究进展

    Institute of Scientific and Technical Information of China (English)

    陈丹洁

    2013-01-01

    抗菌肽是生物防御系统产生的一类对抗外源性病原体的肽类物质,具有抗细菌、真菌、病毒、原虫、癌细胞等多种活性,目前发现抗菌肽或类似抗菌肽的小分子肽类广泛存在于昆虫、两栖类、水产动物及哺乳动物中,具有广阔的应用前景.现就抗菌肽的理化特征、结构特点、应用前景等几个方面系统地阐述水产低值鱼抗菌肽的研究进展.%Antimicrobial peptides are antiexogenous pathogens peptides produced by biological defense system,with various activities such asantibacterial,antifungal,antimould,antivirus,anti-protozoon,and anti-cancer cells, etc. . Studies found that antimicrobial peptides, which have wide application prospects, exist widely in insects, amphibians, aquatic animals and mammals. Here is to make a review on the research progress of the physical and chemical characteristics, the structure characteristics, the application prospect of antimicrobial peptides in aquatic low-value fish.

  6. Progress in Research of Active Antimicrobial Peptides from the Skins of Frog%蛙皮活性抗菌肽最新研究进展

    Institute of Scientific and Technical Information of China (English)

    周庆峰; 赵文锋; 张向飞

    2011-01-01

    蛙皮抗菌肽是生物界中广泛存在的一类生物活性肽,是蛙类生物机体先天性免疫系统中的重要成分.目前,从青蛙皮肤中获得了越来越多结构新颖、作用独特的活性抗菌肽,有望成为感染类以及糖尿病等疾病新的药物资源.此文通过对国内外相关文献进行检索,综合了国内外近年来的研究,对近年来蛙皮抗菌肽的活性研究概况进行综述.%Antimicrobial peptide from the skins of frog is a kind of bioactive peptide existed extensively in nature, and is one key component of the host-resistance apparatus so-called innate immunity. At present, a series of antimicrobial peptide with novel structures and unique function were isolated from frog resources, which were potential resources for anti-infective and diabetes therapeutic drug. By literature retrieval and induction, the progress in research of antimicrobial peptide from the skins of frog was reviewed in this paper.

  7. Connexin43 is dispensable for phagocytosis.

    Science.gov (United States)

    Glass, Aaron M; Wolf, Benjamin J; Schneider, Karin M; Princiotta, Michael F; Taffet, Steven M

    2013-05-01

    Macrophages that lack connexin43 (Cx43), a gap junction protein, have been reported to exhibit dramatic deficiencies in phagocytosis. In this study, we revisit these findings using well-characterized macrophage populations. Cx43 knockout (Cx43(-/-)) mice die soon after birth, making the harvest of macrophages from adult Cx43(-/-) mice problematic. To overcome this obstacle, we used several strategies: mice heterozygous for the deletion of Cx43 were crossed to produce Cx43(+/+) (wild type [WT]) and Cx43(-/-) fetuses. Cells isolated from 12- to 14-d fetal livers were used to reconstitute irradiated recipient animals. After reconstitution, thioglycollate-elicited macrophages were collected by peritoneal lavage and bone marrow was harvested. Bone marrow cells and, alternatively, fetal liver cells were cultured in media containing M-CSF for 7-10 d, resulting in populations of cells that were >95% macrophages based on flow cytometry. Phagocytic uptake was detected using flow cytometric and microscopic techniques. Quantification of phagocytic uptake of IgG-opsonized sheep erythrocytes, zymosan particles, and Listeria monocytogenes failed to show any significant difference between WT and Cx43(-/-) macrophages. Furthermore, the use of particles labeled with pH-sensitive dyes showed equivalent acidification of phagosomes in both WT and Cx43(-/-) macrophages. Our findings suggest that modulation of Cx43 levels in cultured macrophages does not have a significant impact on phagocytosis.

  8. Phagocytosis Affects Biguanide Sensitivity of Acanthamoeba spp.

    Science.gov (United States)

    Noble, Judith A.; Ahearn, Donald G.; Avery, Simon V.; Crow Jr., Sidney A.

    2002-01-01

    The incidence of Acanthamoeba keratitis, a disease associated with contact lens wear, has been in apparent decline with the advent of multipurpose contact lens solutions. The concentrations of the biguanides chlorhexidine digluconate (CHX) and particularly polyhexamethylene biguanide (PHMB) included in multipurpose solutions (MPSs) are sublethal for amoebae. We evaluated by flow cytometry the effects of these two biguanides on phagocytosis of particles and the survival of trophozoites of Acanthamoeba castellanii and A. polyphaga. Trophozoites of A. castellanii and A. polyphaga (106/ml) were exposed to solutions of 5 and 50 μg of PHMB and CHX per ml in the presence and absence of particles (i.e., heat-killed yeasts and bacteria and latex beads). In addition, trophozoites were exposed to particles treated with these concentrations of the two biguanides. In the absence of particles, trophozoites of A. polyphaga appeared to be more resistant to the biguanides than those of A. castellanii. In the presence of particles, the rates of survival of both species were decreased. In most instances, particles treated with sublethal concentrations of both biguanides that were adsorbed onto the particles reduced the incidence of phagocytosis. Particles present in MPSs in contact lens cases may be involved in the decreased incidence of Acanthamoeba keratitis. PMID:12069957

  9. Phagocytosis affects biguanide sensitivity of Acanthamoeba spp.

    Science.gov (United States)

    Noble, Judith A; Ahearn, Donald G; Avery, Simon V; Crow, Sidney A

    2002-07-01

    The incidence of Acanthamoeba keratitis, a disease associated with contact lens wear, has been in apparent decline with the advent of multipurpose contact lens solutions. The concentrations of the biguanides chlorhexidine digluconate (CHX) and particularly polyhexamethylene biguanide (PHMB) included in multipurpose solutions (MPSs) are sublethal for amoebae. We evaluated by flow cytometry the effects of these two biguanides on phagocytosis of particles and the survival of trophozoites of Acanthamoeba castellanii and A. polyphaga. Trophozoites of A. castellanii and A. polyphaga (10(6)/ml) were exposed to solutions of 5 and 50 microg of PHMB and CHX per ml in the presence and absence of particles (i.e., heat-killed yeasts and bacteria and latex beads). In addition, trophozoites were exposed to particles treated with these concentrations of the two biguanides. In the absence of particles, trophozoites of A. polyphaga appeared to be more resistant to the biguanides than those of A. castellanii. In the presence of particles, the rates of survival of both species were decreased. In most instances, particles treated with sublethal concentrations of both biguanides that were adsorbed onto the particles reduced the incidence of phagocytosis. Particles present in MPSs in contact lens cases may be involved in the decreased incidence of Acanthamoeba keratitis.

  10. Identification of Drosophila Gene Products Required for Phagocytosis of Candidaalbicans.

    Directory of Open Access Journals (Sweden)

    2005-12-01

    Full Text Available Phagocytosis is a highly conserved aspect of innate immunity. We used Drosophila melanogaster S2 cells as a model system to study the phagocytosis of Candida albicans, the major fungal pathogen of humans, by screening an RNAi library representing 7,216 fly genes conserved among metazoans. After rescreening the initial genes identified and eliminating certain classes of housekeeping genes, we identified 184 genes required for efficient phagocytosis of C. albicans. Diverse biological processes are represented, with actin cytoskeleton regulation, vesicle transport, signaling, and transcriptional regulation being prominent. Secondary screens using Escherichia coli and latex beads revealed several genes specific for C. albicans phagocytosis. Characterization of one of those gene products, Macroglobulin complement related (Mcr, shows that it is secreted, that it binds specifically to the surface of C. albicans, and that it promotes its subsequent phagocytosis. Mcr is closely related to the four Drosophila thioester proteins (Teps, and we show that TepII is required for efficient phagocytosis of E. coli (but not C. albicans or Staphylococcus aureus and that TepIII is required for the efficient phagocytosis of S. aureus (but not C. albicans or E. coli. Thus, this family of fly proteins distinguishes different pathogens for subsequent phagocytosis.

  11. Influence of Stress-Induced Catecholamines on Macrophage Phagocytosis

    Science.gov (United States)

    1989-04-01

    levels of adenosine-3’, 5"-cyclic monophosphate on phagocytosis: effects on macrophage- Trypanosoma cruzi interaction. J. Immunol. 129:2757. 11 7. Lima...decreased phagocytosis of Trgpanosoma cruzi (6) and IgG-coated erythrocytes (7,B) by mouse macrophages. Alterations in cAMP concentrations influence

  12. Phagocytosis of sperm by follicle cells of the carnivorous sponge Asbestopluma occidentalis (Porifera, Demospongiae).

    Science.gov (United States)

    Riesgo, Ana

    2010-06-01

    During spermatogenesis of the carnivorous sponge Asbestopluma occidentalis, follicle cells that lined the spermatocysts phagocytosed unreleased mature sperm. Such follicle cells are part of the complex envelope that limits spermatocysts of A. occidentalis, which is also comprised of a collagen layer, a thick layer of intertwined cells, and spicules. Follicle cells showed vesicles containing single phagocytosed spermatozoa within their cytoplasm. Additionally, lipids and other inclusions were observed within the cytoplasm of follicle cells. It is likely that follicle cells recapture nutrients by phagocytosing spermatozoa and use them to form lipids and other inclusions. Such sperm phagocytosis is usually performed in higher invertebrates and vertebrates by Sertoli cells that are located in the testis wall. While Sertoli cells develop a wide range of functions such as creating a blood-testis barrier, providing crucial factors to ensure correct progression of spermatogenesis, and phagocytosis of aberrant, degenerating, and unreleased sperm cells, sponge follicle cells may only display phagocytotic activity on spermatogenic cells.

  13. 抗菌肽抗病的研究进展%Research Progress on Antimicrobial Peptide against Diseases

    Institute of Scientific and Technical Information of China (English)

    周继章

    2012-01-01

    Antimicrobial peptide has ability to restrain the growth of bacteria, virus, fungus and cancers. Which is not only no drug resistance, but also no toxic to normal cells. It is a kind of ideal biologies in the future. This paper reviews the relative research about antimicrobial peptide against on bacteria, virus, fungus and cancer, describs the application prospect of AMPs and discusses the existed problems about AMPs at present.%抗菌肽具有广谱杀菌,对病毒、真菌、某些肿瘤具有一定的抑制作用,抗菌肽还具有不产生耐药性,对正常细胞无毒害作用,是一种理想的生物制剂.作者综述了近些年来抗菌肽在抗细菌、病毒、真菌和癌症等方面的相关研究,并就抗菌肽在当前存在的问题和未来巨大的应用前景进行了探讨.

  14. 新型天然抗菌试剂研究进展%Research Progress on New Natural Antimicrobial Agents

    Institute of Scientific and Technical Information of China (English)

    段丽丽; 阎红; 贾洪峰; 周凌洁

    2016-01-01

    随着人们对于食品安全的重视,食品防腐剂作为食品加工和保存中不可缺少的一部分也逐渐得到了广泛的关注。为了防止食物的腐败变质和延长保存时间,加工食品和需要保鲜的瓜果蔬菜等需要在制作加工和包装过程中添加一定的防腐剂来杀死微生物或者抑制微生物的生长来避免腐败。如何在食品加工和保存的过程中使用天然的抗菌试剂来替代传统的具有潜在毒害的化学防腐剂,是目前研究的热点。主要对目前已经研究发现的天然食品防腐剂进行综述,介绍天然食品抗菌剂的来源、分类和抗菌特性,阐释一些新型天然抗菌试剂的研究进展以及天然食品防腐剂研究存在的问题和未来的发展前景,以期能够对食品加工和保存过程中食品防腐剂的选择起到一定的指导作用。%As people pay more attention to food safety,food preservative as an integral part of the food processing and preservation gradually gains wide attention by people.In order to prevent food from decaying and prolong the shelf life,the processed foods and fresh fruits and vegetables need to add certain preservatives to kill microorganisms or inhibit the growth of microorganisms to avoid corruption during the process of making,processing and packaging.In recent years,it has been a hot topic research on finding new natural antimicrobial agents and trying to use them as substitutes of chemical additives which might be harmful to human health.Mainly review on the application of different kinds of natural antimicrobial agents and their source, classification and antimicrobial activity.Meanwhile,discuss about the research process on new natural antimicrobial products all over the world and the problems existed in the research and the development prospect of natural antimicrobial preservatives,in order to play a certain guidance role in the choice of food preservatives in the processing and

  15. Regulation of Microglial Phagocytosis by RhoA/ROCK-Inhibiting Drugs.

    Science.gov (United States)

    Scheiblich, Hannah; Bicker, Gerd

    2017-04-01

    Inflammation within the central nervous system (CNS) is a major component of many neurodegenerative diseases. The underlying mechanisms of neuronal loss are not fully understood, but the activation of CNS resident phagocytic microglia seems to be a significant element contributing to neurodegeneration. At the onset of inflammation, high levels of microglial phagocytosis may serve as an essential prerequisite for creating a favorable environment for neuronal regeneration. However, the excessive and long-lasting activation of microglia and the augmented engulfment of neurons have been suggested to eventually govern widespread neurodegeneration. Here, we investigated in a functional assay of acute inflammation how the small GTPase RhoA and its main target the Rho kinase (ROCK) influence microglial phagocytosis of neuronal debris. Using BV-2 microglia and human NT2 model neurons, we demonstrate that the pain reliever Ibuprofen decreases RhoA activation and microglial phagocytosis of neuronal cell fragments. Inhibition of the downstream effector ROCK with the small-molecule agents Y-27632 and Fasudil reduces the engulfment of neuronal debris and attenuates the production of the inflammatory mediator nitric oxide during stimulation with lipopolysaccharide. Our results support a therapeutic potential for RhoA/ROCK-inhibiting agents as an effective treatment of excessive inflammation and the resulting progression of microglia-mediated neurodegeneration in the CNS.

  16. Vitamin D Deficiency Reduces the Immune Response, Phagocytosis Rate, and Intracellular Killing Rate of Microglial Cells

    Science.gov (United States)

    Onken, Marie Luise; Schütze, Sandra; Redlich, Sandra; Götz, Alexander; Hanisch, Uwe-Karsten; Bertsch, Thomas; Ribes, Sandra; Hanenberg, Andrea; Schneider, Simon; Bollheimer, Cornelius; Sieber, Cornel; Nau, Roland

    2014-01-01

    Meningitis and meningoencephalitis caused by Escherichia coli are associated with high rates of mortality and neurological sequelae. A high prevalence of neurological disorders has been observed in geriatric populations at risk of hypovitaminosis D. Vitamin D has potent effects on human immunity, including induction of antimicrobial peptides (AMPs) and suppression of T-cell proliferation, but its influence on microglial cells is unknown. The purpose of the present study was to determine the effects of vitamin D deficiency on the phagocytosis rate, intracellular killing, and immune response of murine microglial cultures after stimulation with the Toll-like receptor (TLR) agonists tripalmitoyl-S-glyceryl-cysteine (TLR1/2), poly(I·C) (TLR3), lipopolysaccharide (TLR4), and CpG oligodeoxynucleotide (TLR9). Upon stimulation with high concentrations of TLR agonists, the release of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) was decreased in vitamin D-deficient compared to that in vitamin D-sufficient microglial cultures. Phagocytosis of E. coli K1 after stimulation of microglial cells with high concentrations of TLR3, -4, and -9 agonists and intracellular killing of E. coli K1 after stimulation with high concentrations of all TLR agonists were lower in vitamin D-deficient microglial cells than in the respective control cells. Our observations suggest that vitamin D deficiency may impair the resistance of the brain against bacterial infections. PMID:24686054

  17. Caspases regulate VAMP-8 expression and phagocytosis in dendritic cells.

    Science.gov (United States)

    Ho, Yong Hou Sunny; Cai, Deyu Tarika; Huang, Dachuan; Wang, Cheng Chun; Wong, Siew Heng

    2009-09-18

    During an inflammation and upon encountering pathogens, immature dendritic cells (DC) undergo a maturation process to become highly efficient in presenting antigens. This transition from immature to mature state is accompanied by various physiological, functional and morphological changes including reduction of caspase activity and inhibition of phagocytosis in the mature DC. Caspases are cysteine proteases which play essential roles in apoptosis, necrosis and inflammation. Here, we demonstrate that VAMP-8, (a SNARE protein of the early/late endosomes) which has been shown previously to inhibit phagocytosis in DC, is a substrate of caspases. Furthermore, we identified two putative conserved caspase recognition/cleavage sites on the VAMP-8 protein. Consistent with the up-regulation of VAMP-8 expression upon treatment with caspase inhibitor (CI), immature DC treated with CI exhibits lower phagocytosis activity. Thus, our results highlight the role of caspases in regulating VAMP-8 expression and subsequently phagocytosis during maturation of DC.

  18. Phagocytosis: receptors, signal integration, and the cytoskeleton.

    Science.gov (United States)

    Freeman, Spencer A; Grinstein, Sergio

    2014-11-01

    Phagocytosis is a remarkably complex and versatile process: it contributes to innate immunity through the ingestion and elimination of pathogens, while also being central to tissue homeostasis and remodeling by clearing effete cells. The ability of phagocytes to perform such diverse functions rests, in large part, on their vast repertoire of receptors. In this review, we address the various receptor types, their mobility in the plane of the membrane, and two modes of receptor crosstalk: priming and synergy. A major section is devoted to the actin cytoskeleton, which not only governs receptor mobility and clustering but also is instrumental in particle engulfment. Four stages of the actin remodeling process are identified and discussed: (i) the 'resting' stage that precedes receptor engagement, (ii) the disruption of the cortical actin prior to formation of the phagocytic cup, (iii) the actin polymerization that propels pseudopod extension, and (iv) the termination of polymerization and removal of preassembled actin that are required for focal delivery of endomembranes and phagosomal sealing. These topics are viewed in the larger context of the differentiation and polarization of the phagocytic cells.

  19. Cortactin and phagocytosis in isolated Sertoli cells

    Directory of Open Access Journals (Sweden)

    Wolski Katja M

    2005-12-01

    Full Text Available Abstract Background Cortactin, an actin binding protein, has been associated with Sertoli cell ectoplasmic specializations in vivo, based on its immunolocalization around the heads of elongated spermatids, but not previously identified in isolated Sertoli cells. In an in vitro model of Sertoli cell-spermatid binding, cortactin was identified around debris and dead germ cells. Based on this observation, we hypothesized that this actin binding protein may be associated with a non-junction-related physiological function, such as phagocytosis. The purpose of this study was to identify the presence and distribution of cortactin in isolated rat Sertoli cells active in phagocytic activity following the addition of 0.8 μm latex beads. Results Sertoli cell monocultures were incubated with or without follicle stimulating hormone (FSH; 0.1 μg/ml in the presence or absence of cytochalasin D (2 μM, as an actin disrupter. Cortactin was identified by standard immunostaining with anti-cortactin, clone 4F11 (Upstate after incubation times of 15 min, 2 hr, and 24 hr with or without beads. Cells exposed to no hormone and no beads appeared to have a ubiquitous distribution of cortactin throughout the cytoplasm. In the presence of cytochalasin D, cortactin immunostaining was punctate and distributed in a pattern similar to that reported for actin in cells exposed to cytochalasin D. Sertoli cells not exposed to FSH, but activated with beads, did not show cortactin immunostaining around the phagocytized beads at any of the time periods. FSH exposure did not alter the distribution of cortactin within Sertoli cells, even when phagocytic activity was upregulated by the presence of beads. Conclusion Results of this study suggest cortactin is not associated with peripheralized actin at junctional or phagocytic sites. Further studies are necessary to clarify the role of cortactin in Sertoli cells.

  20. Efficient phagocytosis requires triacylglycerol hydrolysis by adipose triglyceride lipase.

    Science.gov (United States)

    Chandak, Prakash G; Radovic, Branislav; Aflaki, Elma; Kolb, Dagmar; Buchebner, Marlene; Fröhlich, Eleonore; Magnes, Christoph; Sinner, Frank; Haemmerle, Guenter; Zechner, Rudolf; Tabas, Ira; Levak-Frank, Sanja; Kratky, Dagmar

    2010-06-25

    Macrophage phagocytosis is an essential biological process in host defense and requires large amounts of energy. To date, glucose is believed to represent the prime substrate for ATP production in macrophages. To investigate the relative contribution of free fatty acids (FFAs) in this process, we determined the phagocytosis rates in normal mouse macrophages and macrophages of adipose triglyceride lipase (ATGL)-deficient mice. ATGL was shown to be the rate-limiting enzyme for the hydrolysis of lipid droplet-associated triacylglycerol (TG) in many tissues. Here, we demonstrate that Atgl(-/-) macrophages fail to efficiently hydrolyze cellular TG stores leading to decreased cellular FFA concentrations and concomitant accumulation of lipid droplets, even in the absence of exogenous lipid loading. The reduced availability of FFAs results in decreased cellular ATP concentrations and impaired phagocytosis suggesting that fatty acids must first go through a cycle of esterification and re-hydrolysis before they are available as energy substrate. Exogenously added glucose cannot fully compensate for the phagocytotic defect in Atgl(-/-) macrophages. Hence, phagocytosis was also decreased in vivo when Atgl(-/-) mice were challenged with bacterial particles. These findings imply that phagocytosis in macrophages depends on the availability of FFAs and that ATGL is required for their hydrolytic release from cellular TG stores. This novel mechanism links ATGL-mediated lipolysis to macrophage function in host defense and opens the way to explore possible roles of ATGL in immune response, inflammation, and atherosclerosis.

  1. Disruption of Sphingolipid Biosynthesis Blocks Phagocytosis of Candida albicans.

    Directory of Open Access Journals (Sweden)

    Fikadu G Tafesse

    2015-10-01

    Full Text Available The ability of phagocytes to clear pathogens is an essential attribute of the innate immune response. The role of signaling lipid molecules such as phosphoinositides is well established, but the role of membrane sphingolipids in phagocytosis is largely unknown. Using a genetic approach and small molecule inhibitors, we show that phagocytosis of Candida albicans requires an intact sphingolipid biosynthetic pathway. Blockade of serine-palmitoyltransferase (SPT and ceramide synthase-enzymes involved in sphingolipid biosynthesis- by myriocin and fumonisin B1, respectively, impaired phagocytosis by phagocytes. We used CRISPR/Cas9-mediated genome editing to generate Sptlc2-deficient DC2.4 dendritic cells, which lack serine palmitoyl transferase activity. Sptlc2-/- DC2.4 cells exhibited a stark defect in phagocytosis, were unable to bind fungal particles and failed to form a normal phagocytic cup to engulf C. albicans. Supplementing the growth media with GM1, the major ganglioside present at the cell surface, restored phagocytic activity of Sptlc2-/- DC2.4 cells. While overall membrane trafficking and endocytic pathways remained functional, Sptlc2-/- DC2.4 cells express reduced levels of the pattern recognition receptors Dectin-1 and TLR2 at the cell surface. Consistent with the in vitro data, compromised sphingolipid biosynthesis in mice sensitizes the animal to C. albicans infection. Sphingolipid biosynthesis is therefore critical for phagocytosis and in vivo clearance of C. albicans.

  2. Interaction of the European genotype porcine reproductive and respiratory syndrome virus (PRRSV with sialoadhesin (CD169/Siglec-1 inhibits alveolar macrophage phagocytosis

    Directory of Open Access Journals (Sweden)

    De Baere Miet I

    2012-05-01

    Full Text Available Abstract Porcine reproductive and respiratory syndrome virus (PRRSV is an arterivirus that shows a restricted in vivo tropism for subsets of porcine macrophages, with alveolar macrophages being major target cells. The virus is associated with respiratory problems in pigs of all ages and is commonly isolated on farms with porcine respiratory disease complex (PRDC. Due to virus-induced macrophage death early in infection, PRRSV hampers the innate defence against pathogens in the lungs. In addition, the virus might also directly affect the antimicrobial functions of macrophages. This study examined whether interaction of European genotype PRRSV with primary alveolar macrophages (PAM affects their phagocytic capacity. Inoculation of macrophages with both subtype I PRRSV (LV and subtype III PRRSV (Lena showed that the virus inhibits PAM phagocytosis. Similar results were obtained using inactivated PRRSV (LV, showing that initial interaction of the virion with the cell is sufficient to reduce phagocytosis, and that no productive infection is required. When macrophages were incubated with sialoadhesin- (Sn or CD163-specific antibodies, two entry mediators of the virus, only Sn-specific antibodies downregulated the phagocytic capacity of PAM, indicating that interaction with Sn, but not CD163, mediates the inhibitory effect of PRRSV on phagocytosis. In conclusion, this study shows that European genotype PRRSV inhibits PAM phagocytosis in vitro, through the interaction with its internalization receptor Sn. If similar events occur in vivo, this interaction may be important in the development of PRDC, as often seen in the field.

  3. Antimicrobial Pesticides

    Science.gov (United States)

    Jump to main content US EPA United States Environmental Protection Agency Search Search Pesticides Share Facebook Twitter Google+ ... of antimicrobial pesticides (Part 158W) Antimicrobials play an important role in public health and safety. While providing ...

  4. Antimicrobial stewardship.

    Science.gov (United States)

    Allerberger, F; Mittermayer, H

    2008-03-01

    The aim of antimicrobial management or stewardship programmes is to ensure proper use of antimicrobial agents in order to provide the best treatment outcomes, to lessen the risk of adverse effects (including antimicrobial resistance), and to promote cost-effectiveness. Increasingly, long-term sustainability is found to be the major focus of antimicrobial stewardship. Implementing structural measures in healthcare institutions is therefore a major, but not the sole, focus of attention in promoting prudent use of antibiotics. The problem of antimicrobial resistance requires common strategies at all levels--for the prescribers and at ward, departmental, hospital, national and international levels.

  5. DMPD: Complement-mediated phagocytosis--the role of Syk. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 16754322 Complement-mediated phagocytosis--the role of Syk. Tohyama Y, Yamamura H. ...IUBMB Life. 2006 May-Jun;58(5-6):304-8. (.png) (.svg) (.html) (.csml) Show Complement-mediated phagocytosis-...-the role of Syk. PubmedID 16754322 Title Complement-mediated phagocytosis--the role of Syk. Authors Tohyama

  6. Feed-forward regulation of phagocytosis by Entamoeba histolytica.

    Science.gov (United States)

    Sateriale, Adam; Vaithilingam, Archana; Donnelly, Liam; Miller, Peter; Huston, Christopher D

    2012-12-01

    The parasitic protozoan Entamoeba histolytica is aptly named for its capacity to destroy host tissue. When E. histolytica trophozoites invade the lamina propria of a host colon, extracellular matrices are degraded while host cells are killed and phagocytosed. The ability of E. histolytica to phagocytose host cells correlates with virulence in vivo. In order to better understand the mechanism of phagocytosis, we used an E. histolytica Affymetrix microarray chip to measure the total gene expression of phagocytic and nonphagocytic subpopulations. Using paramagnetic beads coated with a known host ligand that stimulates phagocytosis, phagocytic and nonphagocytic amoebae from a single culture were purified. Microarray analysis of the subpopulations identified 121 genes with >2-fold higher expression in phagocytic than in nonphagocytic amoebae. Functional annotation identified genes encoding proteins involved in actin binding and cytoskeletal organization as highly enriched gene clusters. Post hoc analyses of selected genes showed that the gene expression profile identified in the microarray experiment did not exist prior to cell sorting but rather was stimulated through phagocytosis. Further, these expression profiles correlated with an increase in phagocytic ability, as E. histolytica cultures exposed to an initial stimulus of phagocytosis showed increased phagocytic ability upon a second stimulus. To our knowledge, this is the first description of such feed-forward regulation of gene expression and phagocytic ability in a phagocyte.

  7. Direct suppression of phagocytosis by amphipathic polymeric surfactants.

    Science.gov (United States)

    Watrous-Peltier, N; Uhl, J; Steel, V; Brophy, L; Merisko-Liversidge, E

    1992-09-01

    Recent studies have demonstrated that phagocytosis of colloidal particles by the mononuclear phagocytes of the liver and spleen can be controlled by either coating or stabilizing particulate carriers with the amphipathic polymeric surfactants, F108 and T908. These surfactants consist of copolymers of polypropylene oxide (PPO) and polyethylene oxide (PEO) and, when adsorbed to particulate surfaces, significantly decrease sequestration of particulates by the mononuclear phagocytes (MPS) of the liver. To evaluate these observations further, murine peritoneal macrophages were incubated for varying periods with surfactant-coated and noncoated polystyrene particles (PSPs). Phagocytosis was monitored using gamma counting and quantitative fluorescence microscopy. The data show that phagocytosis is decreased when PSPs are coated with F108 and T908. In addition, suppression of phagocytic activity was observed when cells were pretreated with the surfactant and then challenged with noncoated particles. The data confirm previous observations that polymeric surfactants consisting of PEO and PPO protect particulate carriers from rapid uptake by the MPS of the liver. Further, F108 and T908 suppress phagocytosis directly without affecting the integrity, viability, or functional state of the cell.

  8. Mechanisms to suppress or enhance phagocytosis of staphylococci

    NARCIS (Netherlands)

    Kuipers, A|info:eu-repo/dai/nl/304811017

    2016-01-01

    Staphylococcus aureus (S. aureus) is a major human pathogen responsible for many community- and hospital-acquired infections. In humans, host clearance of S. aureus critically depends on proper engulfment (phagocytosis) and intracellular killing by phagocytic cells such as neutrophils. In order to

  9. Impaired phagocytosis of apoptotic cells causes accumulation of bone marrow-derived macrophages in aged mice

    Science.gov (United States)

    Kim, Ok-Hee; Kim, Hyojung; Kang, Jinku; Yang, Dongki; Kang, Yu-Hoi; Lee, Dae Ho; Cheon, Gi Jeong; Park, Sang Chul; Oh, Byung-Chul

    2017-01-01

    Accumulation of tissue macrophages is a significant characteristic of disease-associated chronic inflammation, and facilitates the progression of disease pathology. However, the functional roles of these bone marrow-derived macrophages (BMDMs) in aging are unclear. Here, we identified age-dependent macrophage accumulation in the bone marrow, showing that aging significantly increases the number of M1 macrophages and impairs polarization of BMDMs. We found that age-related dysregulation of BMDMs is associated with abnormal overexpression of the anti-inflammatory interleukin-10. BMDM dysregulation in aging impairs the expression levels of pro-inflammatory cytokines and genes involved in B-cell maturation and activation. Phagocytosis of apoptotic Jurkat cells by BMDMs was reduced because of low expression of phagocytic receptor CD14, indicating that increased apoptotic cells may result from defective phagocytosis of apoptotic cells in the BM of aged mice. Therefore, CD14 may represent a promising target for preventing BMDM dysregulation, and macrophage accumulation may provide diagnostic and therapeutic clues. PMID:27866511

  10. Antimicrobial Activity.

    Science.gov (United States)

    2016-01-01

    Natural products of higher plants may possess a new source of antimicrobial agents with possibly novel mechanisms of action. They are effective in the treatment of infectious diseases while simultaneously mitigating many of the side effects that are often associated with conventional antimicrobials. A method using scanning electron microscope (SEM) to study the morphology of the bacterial and fungal microbes and thus determining antimicrobial activity is presented in the chapter.

  11. Caspase-8 Activation Precedes Alterations of Mitochondrial Membrane Potential during Monocyte Apoptosis Induced by Phagocytosis and Killing of Staphylococcus aureus

    Science.gov (United States)

    Węglarczyk, Kazimierz; Baran, Jarosław; Zembala, Marek; Pryjma, Juliusz

    2004-01-01

    Human peripheral blood monocytes become apoptotic following phagocytosis and killing of Staphylococcus aureus. Although this type of monocyte apoptosis is known to be initiated by Fas-Fas ligand (FasL) interactions, the downstream signaling pathway has not been determined. In this work the involvement of mitochondria and the kinetics of caspase-8 and caspase-3 activation after phagocytosis of S. aureus were studied. Caspase-8 activity was measured in cell lysates by using the fluorogenic substrate Ac-IETD-AFC. Active caspase-3 levels and mitochondrial membrane potential (Δψm) were measured in whole cells by flow cytometry using monoclonal antibodies reacting with activated caspase-3 and chloromethyl-X-rosamine, respectively. The results show that caspase-8 was activated shortly after phagocytosis of bacteria. Caspase-8 activation was followed by progressive disruption of Δψm, which is associated with the production of reactive oxygen intermediates. The irreversible caspase-8 inhibitor zIETD-FMK prevented the disruption of Δψm and the release of cytochrome c from S. aureus-exposed monocytes. Caspase-3 activation occurred following disruption of Δψm. These results strongly suggest that apoptosis of monocytes that have phagocytosed and killed S. aureus is driven by the Fas-FasL-initiated pathway, which is typical for type II cells. PMID:15102767

  12. Complement receptor-3 negatively regulates the phagocytosis of degenerated myelin through tyrosine kinase Syk and cofilin

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    Hadas Smadar

    2012-07-01

    Full Text Available Abstract Background Intact myelin, which normally surrounds axons, breaks down in Wallerian degeneration following axonal injury and during neurodegenerative diseases such as multiple sclerosis. Clearance of degenerated myelin by phagocytosis is essential since myelin impedes repair and exacerbates damage. CR3 (complement receptor-3 is a principal phagocytic receptor in myelin phagocytosis. We studied how tyrosine kinase Syk (spleen tyrosine kinase and cofilin control phagocytosis of degenerated myelin by CR3 in microglia and macrophages. Syk is a non-receptor tyrosine kinase that CR3 recruits to convey cellular functions. Cofilin is an actin-depolymerizing protein that controls F-actin (filamentous actin remodeling (i.e., disassembly and reassembly by shifting between active unphosphorylated and inactive phosphorylated states. Results Syk was continuously activated during prolonged phagocytosis. Phagocytosis increased when Syk activity and expression were reduced, suggesting that normally Syk down regulates CR3-mediated myelin phagocytosis. Levels of inactive p-cofilin (phosphorylated cofilin decreased transiently during prolonged phagocytosis. In contrast, p-cofilin levels decreased continuously when Syk activity and expression were continuously reduced, suggesting that normally Syk advances the inactive state of cofilin. Observations also revealed inverse relationships between levels of phagocytosis and levels of inactive p-cofilin, suggesting that active unphosphorylated cofilin advances phagocytosis. Active cofilin could advance phagocytosis by promoting F-actin remodeling, which supports the production of membrane protrusions (e.g., filopodia, which, as we also revealed, are instrumental in myelin phagocytosis. Conclusions CR3 both activates and downregulates myelin phagocytosis at the same time. Activation was previously documented. We presently demonstrate that downregulation is mediated through Syk, which advances the inactive

  13. Thrombocytopenia in Plasmodium vivax malaria is related to platelets phagocytosis.

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    Helena Cristina C Coelho

    Full Text Available BACKGROUND: Although thrombocytopenia is a hematological disorder commonly reported in malarial patients, its mechanisms are still poorly understood, with only a few studies focusing on the role of platelets phagocytosis. METHODS AND FINDINGS: Thirty-five malaria vivax patients and eight healthy volunteers (HV were enrolled in the study. Among vivax malaria patients, thrombocytopenia (<150,000 platelets/µL was found in 62.9% (22/35. Mean platelet volume (MPV was higher in thrombocytopenic patients as compared to non-thrombocytopenic patients (p = 0.017 and a negative correlation was found between platelet count and MPV (r = -0.483; p = 0.003. Platelets from HV or patients were labeled with 5-chloromethyl fluorescein diacetate (CMFDA, incubated with human monocytic cell line (THP-1 and platelet phagocytosis index was analyzed by flow cytometry. The phagocytosis index was higher in thrombocytopenic patients compared to non-thrombocytopenic patients (p = 0.042 and HV (p = 0.048. A negative correlation was observed between platelet count and phagocytosis index (r = -0.402; p = 0.016. Platelet activation was assessed measuring the expression of P-selectin (CD62-P in platelets' surface by flow cytometry. No significant difference was found in the expression of P-selectin between thrombocytopenic patients and HV (p = 0.092. After evaluating the cytokine profile (IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ and IL-17 in the patients' sera, levels of IL-6, IL-10 and IFN-γ were elevated in malaria patients compared to HV. Moreover, IL-6 and IL-10 values were higher in thrombocytopenic patients than non-thrombocytopenic ones (p = 0.044 and p = 0.017, respectively. In contrast, TNF-α levels were not different between the three groups, but a positive correlation was found between TNF-α and phagocytosis index (r = -0.305; p = 0.037. CONCLUSION/SIGNIFICANCE: Collectively, our findings indicate that platelet

  14. O-glycosylation in cell wall proteins in Scedosporium prolificans is critical for phagocytosis and inflammatory cytokines production by macrophages.

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    Mariana I D S Xisto

    Full Text Available In this study, we analyze the importance of O-linked oligosaccharides present in peptidorhamnomannan (PRM from the cell wall of the fungus Scedosporium prolificans for recognition and phagocytosis of conidia by macrophages. Adding PRM led to a dose-dependent inhibition of conidia phagocytosis, whereas de-O-glycosylated PRM did not show any effect. PRM induced the release of macrophage-derived antimicrobial compounds. However, O-linked oligosaccharides do not appear to be required for such induction. The effect of PRM on conidia-induced macrophage killing was examined using latex beads coated with PRM or de-O-glycosylated PRM. A decrease in macrophage viability similar to that caused by conidia was detected. However, macrophage killing was unaffected when beads coated with de-O-glycosylated PRM were used, indicating the toxic effect of O-linked oligosaccharides on macrophages. In addition, PRM triggered TNF-α release by macrophages. Chemical removal of O-linked oligosaccharides from PRM abolished cytokine induction, suggesting that the O-linked oligosaccharidic chains are important moieties involved in inflammatory responses through the induction of TNF-α secretion. In summary, we show that O-glycosylation plays a role in the recognition and uptake of S. prolificans by macrophages, killing of macrophages and production of pro- inflammatory cytokines.

  15. O-Glycosylation in Cell Wall Proteins in Scedosporium prolificans Is Critical for Phagocytosis and Inflammatory Cytokines Production by Macrophages

    Science.gov (United States)

    Xisto, Mariana I. D. S.; Bittencourt, Vera C. B.; Liporagi-Lopes, Livia Cristina; Haido, Rosa M. T.; Mendonça, Morena S. A.; Sassaki, Guilherme; Figueiredo, Rodrigo T.; Romanos, Maria Teresa V.; Barreto-Bergter, Eliana

    2015-01-01

    In this study, we analyze the importance of O-linked oligosaccharides present in peptidorhamnomannan (PRM) from the cell wall of the fungus Scedosporium prolificans for recognition and phagocytosis of conidia by macrophages. Adding PRM led to a dose-dependent inhibition of conidia phagocytosis, whereas de-O-glycosylated PRM did not show any effect. PRM induced the release of macrophage-derived antimicrobial compounds. However, O-linked oligosaccharides do not appear to be required for such induction. The effect of PRM on conidia-induced macrophage killing was examined using latex beads coated with PRM or de-O-glycosylated PRM. A decrease in macrophage viability similar to that caused by conidia was detected. However, macrophage killing was unaffected when beads coated with de-O-glycosylated PRM were used, indicating the toxic effect of O-linked oligosaccharides on macrophages. In addition, PRM triggered TNF-α release by macrophages. Chemical removal of O-linked oligosaccharides from PRM abolished cytokine induction, suggesting that the O-linked oligosaccharidic chains are important moieties involved in inflammatory responses through the induction of TNF-α secretion. In summary, we show that O-glycosylation plays a role in the recognition and uptake of S. prolificans by macrophages, killing of macrophages and production of pro- inflammatory cytokines. PMID:25875427

  16. Recent Advances in Antimicrobial Polymers: A Mini-Review

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    Keng-Shiang Huang

    2016-09-01

    Full Text Available Human safety and well-being is threatened by microbes causing numerous infectious diseases resulting in a large number of deaths every year. Despite substantial progress in antimicrobial drugs, many infectious diseases remain difficult to treat. Antimicrobial polymers offer a promising antimicrobial strategy for fighting pathogens and have received considerable attention in both academic and industrial research. This mini-review presents the advances made in antimicrobial polymers since 2013. Antimicrobial mechanisms exhibiting either passive or active action and polymer material types containing bound or leaching antimicrobials are introduced. This article also addresses the applications of these antimicrobial polymers in the medical, food, and textile industries.

  17. Recent Advances in Antimicrobial Polymers: A Mini-Review.

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    Huang, Keng-Shiang; Yang, Chih-Hui; Huang, Shu-Ling; Chen, Cheng-You; Lu, Yuan-Yi; Lin, Yung-Sheng

    2016-09-20

    Human safety and well-being is threatened by microbes causing numerous infectious diseases resulting in a large number of deaths every year. Despite substantial progress in antimicrobial drugs, many infectious diseases remain difficult to treat. Antimicrobial polymers offer a promising antimicrobial strategy for fighting pathogens and have received considerable attention in both academic and industrial research. This mini-review presents the advances made in antimicrobial polymers since 2013. Antimicrobial mechanisms exhibiting either passive or active action and polymer material types containing bound or leaching antimicrobials are introduced. This article also addresses the applications of these antimicrobial polymers in the medical, food, and textile industries.

  18. Stimulation of Paramecium phagocytosis by phorbol ester and forskolin.

    Science.gov (United States)

    Wyroba, E

    1987-09-01

    Phorbol ester (PMA) exerted a dose- and time- dependent stimulating effect on phagocytosis in axenic Paramecium aurelia. When cells were exposed to 200-800 nM PMA in the presence of latex beads, the phagocytic coefficient was enhanced 2.25 to 3.14 times, during 10 min of continuous treatment and then rapidly declined. A similar effect was observed when the cells were exposed to a forskolin treatment, which resulted in nearly a twofold increase in phagocytic activity after a 10 min pulse. Both PMA and forskolin strongly stimulated phagocytosis (i.e. fivefold and threefold, respectively) in cells in which such activity had been completely inhibited by pre-exposure to the beta-receptor antagonist 1-propranolol.

  19. Integrins and small GTPases as modulators of phagocytosis.

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    Sayedyahossein, Samar; Dagnino, Lina

    2013-01-01

    Phagocytosis is the mechanism whereby cells engulf large particles. This process has long been recognized as a critical component of the innate immune response, which constitutes the organism's defense against microorganisms. In addition, phagocytic internalization of apoptotic cells or cell fragments plays important roles in tissue homeostasis and remodeling. Phagocytosis requires target interactions with receptors on the plasma membrane of the phagocytic cell. Integrins have been identified as important mediators of particle clearance, in addition to their well-established roles in cell adhesion, migration and mechanotransduction. Indeed, these ubiquitously expressed proteins impart phagocytic capacity to epithelial, endothelial and mesenchymal cell types. The importance of integrins in particle internalization is emphasized by the ability of microbial and viral pathogens to exploit their signaling pathways to invade host cells, and by the wide variety of disorders that arise from abnormalities in integrin-dependent phagocytic uptake.

  20. The Physiology of Phagocytosis in the Context of Mitochondrial Origin.

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    Martin, William F; Tielens, Aloysius G M; Mentel, Marek; Garg, Sriram G; Gould, Sven B

    2017-09-01

    How mitochondria came to reside within the cytosol of their host has been debated for 50 years. Though current data indicate that the last eukaryote common ancestor possessed mitochondria and was a complex cell, whether mitochondria or complexity came first in eukaryotic evolution is still discussed. In autogenous models (complexity first), the origin of phagocytosis poses the limiting step at eukaryote origin, with mitochondria coming late as an undigested growth substrate. In symbiosis-based models (mitochondria first), the host was an archaeon, and the origin of mitochondria was the limiting step at eukaryote origin, with mitochondria providing bacterial genes, ATP synthesis on internalized bioenergetic membranes, and mitochondrion-derived vesicles as the seed of the eukaryote endomembrane system. Metagenomic studies are uncovering new host-related archaeal lineages that are reported as complex or phagocytosing, although images of such cells are lacking. Here we review the physiology and components of phagocytosis in eukaryotes, critically inspecting the concept of a phagotrophic host. From ATP supply and demand, a mitochondrion-lacking phagotrophic archaeal fermenter would have to ingest about 34 times its body weight in prokaryotic prey to obtain enough ATP to support one cell division. It would lack chemiosmotic ATP synthesis at the plasma membrane, because phagocytosis and chemiosmosis in the same membrane are incompatible. It would have lived from amino acid fermentations, because prokaryotes are mainly protein. Its ATP yield would have been impaired relative to typical archaeal amino acid fermentations, which involve chemiosmosis. In contrast, phagocytosis would have had great physiological benefit for a mitochondrion-bearing cell. Copyright © 2017 American Society for Microbiology.

  1. [Antimicrobial susceptibility in Chile 2012].

    Science.gov (United States)

    Cifuentes-D, Marcela; Silva, Francisco; García, Patricia; Bello, Helia; Briceño, Isabel; Calvo-A, Mario; Labarca, Jaime

    2014-04-01

    Bacteria antimicrobial resistance is an uncontrolled public health problem that progressively increases its magnitude and complexity. The Grupo Colaborativo de Resistencia, formed by a join of experts that represent 39 Chilean health institutions has been concerned with bacteria antimicrobial susceptibility in our country since 2008. In this document we present in vitro bacterial susceptibility accumulated during year 2012 belonging to 28 national health institutions that represent about 36% of hospital discharges in Chile. We consider of major importance to report periodically bacteria susceptibility so to keep the medical community updated to achieve target the empirical antimicrobial therapies and the control measures and prevention of the dissemination of multiresistant strains.

  2. Microglial phagocytosis induced by fibrillar β-amyloid is attenuated by oligomeric β-amyloid: implications for Alzheimer's disease

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    Lin Nan

    2011-06-01

    receptor FcγRIII, and significantly increased that of formyl peptide receptor 2 (FPR2 and scavenger receptor class B1 (SRB1, compared with the basal level. Interestingly, the pre-stimulation with oAβ(1-42 or the inflammatory and oxidative milieu (IL-1β, LPS or t-BHP significantly downregulated the fAβ(1-42-induced mRNA over-expression of CD36, CD47 and Itgb1 receptors in microglial cells. Conclusion These results imply that Aβ oligomers induce a potent inflammatory response and subsequently disturb microglial phagocytosis and clearance of Aβ fibrils, thereby contributing to an initial neurodegenerative characteristic of AD. Antiinflammatory and antioxidative therapies may indeed prove beneficial to delay the progression of AD.

  3. Mechanics of neutrophil phagocytosis: experiments and quantitative models.

    Science.gov (United States)

    Herant, Marc; Heinrich, Volkmar; Dembo, Micah

    2006-05-01

    To quantitatively characterize the mechanical processes that drive phagocytosis, we observed the FcgammaR-driven engulfment of antibody-coated beads of diameters 3 mum to 11 mum by initially spherical neutrophils. In particular, the time course of cell morphology, of bead motion and of cortical tension were determined. Here, we introduce a number of mechanistic models for phagocytosis and test their validity by comparing the experimental data with finite element computations for multiple bead sizes. We find that the optimal models involve two key mechanical interactions: a repulsion or pressure between cytoskeleton and free membrane that drives protrusion, and an attraction between cytoskeleton and membrane newly adherent to the bead that flattens the cell into a thin lamella. Other models such as cytoskeletal expansion or swelling appear to be ruled out as main drivers of phagocytosis because of the characteristics of bead motion during engulfment. We finally show that the protrusive force necessary for the engulfment of large beads points towards storage of strain energy in the cytoskeleton over a large distance from the leading edge ( approximately 0.5 microm), and that the flattening force can plausibly be generated by the known concentrations of unconventional myosins at the leading edge.

  4. Ankyrin-repeat proteins from sponge symbionts modulate amoebal phagocytosis.

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    Nguyen, Mary T H D; Liu, Michael; Thomas, Torsten

    2014-03-01

    Bacteria-eukaryote symbiosis occurs in all stages of evolution, from simple amoebae to mammals, and from facultative to obligate associations. Sponges are ancient metazoans that form intimate symbiotic interactions with complex communities of bacteria. The basic nutritional requirements of the sponge are in part satisfied by the phagocytosis of bacterial food particles from the surrounding water. How bacterial symbionts, which are permanently associated with the sponge, survive in the presence of phagocytic cells is largely unknown. Here, we present the discovery of a genomic fragment from an uncultured gamma-proteobacterial sponge symbiont that encodes for four proteins, whose closest known relatives are found in a sponge genome. Through recombinant approaches, we show that these four eukaryotic-like, ankyrin-repeat proteins (ARP) when expressed in Eschericha coli can modulate phagocytosis of amoebal cells and lead to accumulation of bacteria in the phagosome. Mechanistically, two ARPs appear to interfere with phagosome development in a similar way to reduced vacuole acidification, by blocking the fusion of the early phagosome with the lysosome and its digestive enzymes. Our results show that ARP from sponge symbionts can function to interfere with phagocytosis, and we postulate that this might be one mechanism by which symbionts can escape digestion in a sponge host.

  5. Serotonin modulates insect hemocyte phagocytosis via two different serotonin receptors.

    Science.gov (United States)

    Qi, Yi-Xiang; Huang, Jia; Li, Meng-Qi; Wu, Ya-Su; Xia, Ren-Ying; Ye, Gong-Yin

    2016-03-14

    Serotonin (5-HT) modulates both neural and immune responses in vertebrates, but its role in insect immunity remains uncertain. We report that hemocytes in the caterpillar, Pieris rapae are able to synthesize 5-HT following activation by lipopolysaccharide. The inhibition of a serotonin-generating enzyme with either pharmacological blockade or RNAi knock-down impaired hemocyte phagocytosis. Biochemical and functional experiments showed that naive hemocytes primarily express 5-HT1B and 5-HT2B receptors. The blockade of 5-HT1B significantly reduced phagocytic ability; however, the blockade of 5-HT2B increased hemocyte phagocytosis. The 5-HT1B-null Drosophila melanogaster mutants showed higher mortality than controls when infected with bacteria, due to their decreased phagocytotic ability. Flies expressing 5-HT1B or 5-HT2B RNAi in hemocytes also showed similar sensitivity to infection. Combined, these data demonstrate that 5-HT mediates hemocyte phagocytosis through 5-HT1B and 5-HT2B receptors and serotonergic signaling performs critical modulatory functions in immune systems of animals separated by 500 million years of evolution.

  6. Research Progress of the Antimicrobial Peptides with Dualfunctionality of Spermicide and Microbicide%杀精抗菌功能抗菌肽的研究进展

    Institute of Scientific and Technical Information of China (English)

    张尉(综述); 侯丽; 于和鸣(审校)

    2013-01-01

      抗菌肽(antimicrobial peptides)是广泛存在于生物体内的一类抵抗外源性病原微生物致病作用的防御性小分子多肽。抗菌肽拥有巨大的抗菌潜能和广泛的抗菌谱,以及安全、无毒副作用等特点,其中有些抗菌肽还展现了强有力的杀精避孕功能。综述Magainin,Dermaseptins,Nisin和Subtilosin 4种抗菌肽的杀精抗菌功能,为研制具有杀精抗菌双功能的生物制剂提供新的思路和来源。%Antimicrobial peptides are of important components of low-molecular weight peptides to defense organisms invasion. Antimicrobial peptides have many characteristics,such as the big antibacterial potential,broad antibacterial spectrum,safety,and non-toxic. Some of them also have powerful spermicidal and contraceptive potential. This review introduced the difunctionality of spermicide and microbicide of four antimicrobial peptides,including Magainin,Dermaseptins,Nisin and Subtilosin,which could provide us new ideas to develop the biological products with the difunctionality of spermicide and microbicide.

  7. Antimicrobial Resistance

    Science.gov (United States)

    ... emergence and spread of antibacterial resistance, including optimal use of antibiotics in both humans and animals. A global action plan on antimicrobial resistance was adopted by Member States at the ...

  8. Phagocytic receptors activate and immune inhibitory receptor SIRPalpha inhibits phagocytosis through paxillin and cofilin

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    Miri eGitik

    2014-04-01

    Full Text Available The innate-immune function of phagocytosis of apoptotic cells, tissue-debris, pathogens and cancer cells is essential for homeostasis, tissue repair, fighting infection and combating malignancy. Phagocytosis is carried out in the CNS by resident microglia and in both CNS and PNS by recruited macrophages. While phagocytosis proceeds, bystander healthy cells protect themselves by sending a do not eat me message to phagocytes as CD47 on their surface ligates immune inhibitory receptor SIRPα on the surface of phagocytes and SIRPα then produces the signaling which inhibits phagocytosis. This helpful mechanism becomes harmful when tissue-debris and unhealthy cells inhibit their own phagocytosis by employing the same mechanism. However, the inhibitory signaling that SIRPα produces has not been fully revealed. We focus here on how SIRPα inhibits the phagocytosis of the tissue-debris degenerated-myelin which hinders repair in axonal injury and neurodegenerative diseases. We tested whether SIRPα inhibits phagocytosis by regulating cytoskeleton function through paxillin and cofilin since (a the cytoskeleton generates the mechanical forces that drive phagocytosis and (b both paxillin and cofilin control cytoskeleton function. Paxillin and cofilin were transiently activated in microglia as phagocytosis was activated. In contrast, paxillin and cofilin were continuously activated and phagocytosis augmented in microglia in which SIRPα expression was knocked-down by SIRPα-shRNA. Further, levels of phagocytosis, paxillin activation and cofilin activation positively correlated with one another. Taken together, these observations suggest a novel mechanism whereby paxillin and cofilin are targeted to control phagocytosis by both the activating signaling that phagocytic receptors produce by promoting the activation of paxillin and cofilin and the inhibiting signaling that immune inhibitory SIRPα produces by promoting the inactivation of paxillin and cofilin.

  9. Phagocytic receptors activate and immune inhibitory receptor SIRPα inhibits phagocytosis through paxillin and cofilin.

    Science.gov (United States)

    Gitik, Miri; Kleinhaus, Rachel; Hadas, Smadar; Reichert, Fanny; Rotshenker, Shlomo

    2014-01-01

    The innate immune function of phagocytosis of apoptotic cells, tissue debris, pathogens, and cancer cells is essential for homeostasis, tissue repair, fighting infection, and combating malignancy. Phagocytosis is carried out in the central nervous system (CNS) by resident microglia and in both CNS and peripheral nervous system by recruited macrophages. While phagocytosis proceeds, bystander healthy cells protect themselves by sending a "do not eat me" message to phagocytes as CD47 on their surface ligates immune inhibitory receptor SIRPα on the surface of phagocytes and SIRPα then produces the signaling which inhibits phagocytosis. This helpful mechanism becomes harmful when tissue debris and unhealthy cells inhibit their own phagocytosis by employing the same mechanism. However, the inhibitory signaling that SIRPα produces has not been fully revealed. We focus here on how SIRPα inhibits the phagocytosis of the tissue debris "degenerated myelin" which hinders repair in axonal injury and neurodegenerative diseases. We tested whether SIRPα inhibits phagocytosis by regulating cytoskeleton function through paxillin and cofilin since (a) the cytoskeleton generates the mechanical forces that drive phagocytosis and (b) both paxillin and cofilin control cytoskeleton function. Paxillin and cofilin were transiently activated in microglia as phagocytosis was activated. In contrast, paxillin and cofilin were continuously activated and phagocytosis augmented in microglia in which SIRPα expression was knocked-down by SIRPα-shRNA. Further, levels of phagocytosis, paxillin activation, and cofilin activation positively correlated with one another. Taken together, these observations suggest a novel mechanism whereby paxillin and cofilin are targeted to control phagocytosis by both the activating signaling that phagocytic receptors produce by promoting the activation of paxillin and cofilin and the inhibiting signaling that immune inhibitory SIRPα produces by promoting the

  10. Mitochondrial Transfer via Tunneling Nanotubes is an Important Mechanism by Which Mesenchymal Stem Cells Enhance Macrophage Phagocytosis in the In Vitro and In Vivo Models of ARDS.

    Science.gov (United States)

    Jackson, Megan V; Morrison, Thomas J; Doherty, Declan F; McAuley, Daniel F; Matthay, Michael A; Kissenpfennig, Adrien; O'Kane, Cecilia M; Krasnodembskaya, Anna D

    2016-08-01

    Mesenchymal stromal cells (MSC) have been reported to improve bacterial clearance in preclinical models of Acute Respiratory Distress Syndrome (ARDS) and sepsis. The mechanism of this effect is not fully elucidated yet. The primary objective of this study was to investigate the hypothesis that the antimicrobial effect of MSC in vivo depends on their modulation of macrophage phagocytic activity which occurs through mitochondrial transfer. We established that selective depletion of alveolar macrophages (AM) with intranasal (IN) administration of liposomal clodronate resulted in complete abrogation of MSC antimicrobial effect in the in vivo model of Escherichia coli pneumonia. Furthermore, we showed that MSC administration was associated with enhanced AM phagocytosis in vivo. We showed that direct coculture of MSC with monocyte-derived macrophages enhanced their phagocytic capacity. By fluorescent imaging and flow cytometry we demonstrated extensive mitochondrial transfer from MSC to macrophages which occurred at least partially through tunneling nanotubes (TNT)-like structures. We also detected that lung macrophages readily acquire MSC mitochondria in vivo, and macrophages which are positive for MSC mitochondria display more pronounced phagocytic activity. Finally, partial inhibition of mitochondrial transfer through blockage of TNT formation by MSC resulted in failure to improve macrophage bioenergetics and complete abrogation of the MSC effect on macrophage phagocytosis in vitro and the antimicrobial effect of MSC in vivo. Collectively, this work for the first time demonstrates that mitochondrial transfer from MSC to innate immune cells leads to enhancement in phagocytic activity and reveals an important novel mechanism for the antimicrobial effect of MSC in ARDS. Stem Cells 2016;34:2210-2223.

  11. Regulation of phagocytosis in macrophages by neuraminidase 1.

    Science.gov (United States)

    Seyrantepe, Volkan; Iannello, Alexandre; Liang, Feng; Kanshin, Evgeny; Jayanth, Preethi; Samarani, Suzanne; Szewczuk, Myron R; Ahmad, Ali; Pshezhetsky, Alexey V

    2010-01-01

    The differentiation of monocytes into macrophages and dendritic cells is accompanied by induction of cell-surface neuraminidase 1 (Neu1) and cathepsin A (CathA), the latter forming a complex with and activating Neu1. To clarify the biological importance of this phenomenon we have developed the gene-targeted mouse models of a CathA deficiency (CathA(S190A)) and a double CathA/Neu1 deficiency (CathA(S190A-Neo)). Macrophages of CathA(S190A-Neo) mice and their immature dendritic cells showed a significantly reduced capacity to engulf Gram-positive and Gram-negative bacteria and positively and negatively charged polymer beads as well as IgG-opsonized beads and erythrocytes. Properties of the cells derived from CathA(S190A) mice were indistinguishable from those of wild-type controls, suggesting that the absence of Neu1, which results in the increased sialylation of the cell surface proteins, probably affects multiple receptors for phagocytosis. Indeed, treatment of the cells with purified mouse Neu1 reduced surface sialylation and restored phagocytosis. Because Neu1-deficient cells showed reduced internalization of IgG-opsonized sheep erythrocytes whereas binding of the erythrocytes to the cells at 4 degrees C persisted, we speculate that the absence of Neu1 in particular affected transduction of signals from the Fc receptors for immunoglobulin G (FcgammaR). Indeed the macrophages from the Neu1-deficient mice showed increased sialylation and impaired phosphorylation of FcgammaR as well as markedly reduced phosphorylation of Syk kinase in response to treatment with IgG-opsonized beads. Altogether our data suggest that the cell surface Neu1 activates the phagocytosis in macrophages and dendritic cells through desialylation of surface receptors, thus, contributing to their functional integrity.

  12. Xpf suppresses the mutagenic consequences of phagocytosis in Dictyostelium

    Science.gov (United States)

    Langenick, Judith; Zhang, Xiao-Yin; Traynor, David; Kay, Robert R.

    2016-01-01

    ABSTRACT As time passes, mutations accumulate in the genomes of all living organisms. These changes promote genetic diversity, but also precipitate ageing and the initiation of cancer. Food is a common source of mutagens, but little is known about how nutritional factors cause lasting genetic changes in the consuming organism. Here, we describe an unusual genetic interaction between DNA repair in the unicellular amoeba Dictyostelium discoideum and its natural bacterial food source. We found that Dictyostelium deficient in the DNA repair nuclease Xpf (xpf−) display a severe and specific growth defect when feeding on bacteria. Despite being proficient in the phagocytosis and digestion of bacteria, over time, xpf− Dictyostelium feeding on bacteria cease to grow and in many instances die. The Xpf nuclease activity is required for sustained growth using a bacterial food source. Furthermore, the ingestion of this food source leads to a striking accumulation of mutations in the genome of xpf− Dictyostelium. This work therefore establishes Dictyostelium as a model genetic system to dissect nutritional genotoxicity, providing insight into how phagocytosis can induce mutagenesis and compromise survival fitness. PMID:27872153

  13. Effects of endogenous antidiuretic hormone (ADH) on macrophage phagocytosis

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    Fernandez-Repollet, E.; Opava-Stitzer, S.; Tiffany, S.; Schwartz, A.

    1983-07-01

    Although several studies have indicated that antidiuretic hormone (ADH) enhances the phagocytic function of the reticuloendothelial system (RES) in shock syndromes, it remains unknown what influence ADH exerts upon the individual phagocytic components of this system. The present investigation was designed to evaluate the effects of endogenous ADH on the phagocytic activity of peritoneal macrophage cells. As a phagocytic stimuli, fluorescent methacrylate microbeads were injected intraperitoneally into Brattleboro (ADH deficient) and normal Long Evans rats in the presence and absence of exogenous ADH. Peritoneal cells were harvested 19-22 hr after the administration of the microbeads and the percent phagocytosis was determined in macrophage cells using a fluorescence-activated cell sorter (FACS II). Our results indicate that the percentage of peritoneal macrophages ingesting the fluorescent methacrylate microbeads was significantly reduced in the absence of ADH (Brattleboro rats: 5.4 +/- 0.6% versus Long Evans rats: 16.8 +/- 2.3%; p less than 0.001). In addition, our data demonstrate that exogenous administration of ADH significantly enhanced macrophage phagocytosis in Brattleboro (14.7 +/- 2.2%) and normal Long Evans (49.6 +/- 4.5%) rats. These data suggest, for the first time, that endogenous ADH might play a modulatory role in the phagocytic activity of a specific component of the RES, namely, the macrophage cell.

  14. Prey capture and phagocytosis in the choanoflagellate Salpingoeca rosetta.

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    Mark J Dayel

    Full Text Available Choanoflagellates are unicellular and colonial aquatic microeukaryotes that capture bacteria using an apical flagellum surrounded by a feeding collar composed of actin-filled microvilli. Flow produced by the apical flagellum drives prey bacteria to the feeding collar for phagocytosis. We report here on the cell biology of prey capture in rosette-shaped colonies and unicellular "thecate" or substrate attached cells from the choanoflagellate S. rosetta. In thecate cells and rosette colonies, phagocytosis initially involves fusion of multiple microvilli, followed by remodeling of the collar membrane to engulf the prey, and transport of engulfed bacteria into the cell. Although both thecate cells and rosette colony cells produce ∼ 70 nm "collar links" that connect and potentially stabilize adjacent microvilli, only thecate cells were observed to produce a lamellipod-like "collar skirt" that encircles the base of the collar. This study offers insight into the process of prey ingestion by S. rosetta, and provides a context within which to consider potential ecological differences between solitary cells and colonies in choanoflagellates.

  15. Recent Advances in Antimicrobial Polymers: A Mini-Review

    OpenAIRE

    Huang, Keng-Shiang; Yang, Chih-Hui; Huang, Shu-Ling; Chen, Cheng-You; Lu, Yuan-Yi; Lin, Yung-Sheng

    2016-01-01

    Human safety and well-being is threatened by microbes causing numerous infectious diseases resulting in a large number of deaths every year. Despite substantial progress in antimicrobial drugs, many infectious diseases remain difficult to treat. Antimicrobial polymers offer a promising antimicrobial strategy for fighting pathogens and have received considerable attention in both academic and industrial research. This mini-review presents the advances made in antimicrobial polymers since 2013....

  16. Identification of Drosophila gene products required for phagocytosis of Candida albicans.

    Directory of Open Access Journals (Sweden)

    Shannon L Stroschein-Stevenson

    2006-01-01

    Full Text Available Phagocytosis is a highly conserved aspect of innate immunity. We used Drosophila melanogaster S2 cells as a model system to study the phagocytosis of Candida albicans, the major fungal pathogen of humans, by screening an RNAi library representing 7,216 fly genes conserved among metazoans. After rescreening the initial genes identified and eliminating certain classes of housekeeping genes, we identified 184 genes required for efficient phagocytosis of C. albicans. Diverse biological processes are represented, with actin cytoskeleton regulation, vesicle transport, signaling, and transcriptional regulation being prominent. Secondary screens using Escherichia coli and latex beads revealed several genes specific for C. albicans phagocytosis. Characterization of one of those gene products, Macroglobulin complement related (Mcr, shows that it is secreted, that it binds specifically to the surface of C. albicans, and that it promotes its subsequent phagocytosis. Mcr is closely related to the four Drosophila thioester proteins (Teps, and we show that TepII is required for efficient phagocytosis of E. coli (but not C. albicans or Staphylococcus aureus and that TepIII is required for the efficient phagocytosis of S. aureus (but not C. albicans or E. coli. Thus, this family of fly proteins distinguishes different pathogens for subsequent phagocytosis.

  17. Cholesterol-rich domains are involved in Bordetella pertussis phagocytosis and intracellular survival in neutrophils

    NARCIS (Netherlands)

    Lamberti, Yanina; Perez Vidakovics, Maria Laura; Van der Pol, Ludo-W.; Eugenia Rodriguez, Maria

    2008-01-01

    Bordetella pertussis-specific antibodies protect against whooping cough by facilitating host defense mechanisms such as phagocytosis However. the mechanism involved in the phagocytosis of the bacteria under non-opsonic conditions is still poorly characterized. We report here that B. pertussis bindin

  18. 抗菌肽的研究进展及应用前景%Progress of antimicrobial peptides research and application

    Institute of Scientific and Technical Information of China (English)

    尹昆仑; 王嘉榕; 孙红宾

    2015-01-01

    抗菌肽( antimicrobial peptides, AMPs)是自然界生物体内非常重要的防御体系,能够对抗细菌、真菌、病毒甚至肿瘤细胞。抗菌肽具有广谱抗菌活性,且不易产生耐药性,这使得抗菌肽成为应用前景非常广阔的抑菌剂。本文综述了抗菌肽的来源、功能及其作用机制,并对其应用前景进行展望。%Antimicrobial peptides ( AMPs) are critical component of the innate immune system of organisms, and have been demonstrated with the activity against a variety of microorganisms including bacteria, yeast, fungi, viruses and even tumor cells.Broad-spectrum activity and low propensity for resistance development make the AMPs as a kind of great potential for development of new anti-infective agents.In this paper, the origins, the action, the mechanism, the application prospects are reviewed.

  19. Recent progress in physicochemical characteristics of antimicrobial peptides%抗菌肽理化性质的研究进展

    Institute of Scientific and Technical Information of China (English)

    陈武; 黎定军; 丁彦; 肖启明; 周清明

    2012-01-01

    Antimicrobial peptides (AMPs) comprise an important part of the innate immunity system of host organism and provide effective protection for the host against bacteria, fungi, protozoa and viruses. They are synthesized either by ribosomal or non-ribosomal peptide synthetase. Usually, AMPs are positively charged small molecular weight proteins and have both a hydrophobic and hydrophilic side that enables the molecule to enter the membrane lipid bilayer. In this review, recent discoveries on such physicochemical characteristics of AMPs as conformation, cationicity, hydrophobicity, amphipathicity etc.are discussed.%抗菌肽(antimicrobial peptides,AMPs)是生物先天免疫系统的重要组成部分,由核糖体或非核糖体肽合成酶合成,可协助宿主有效应对细菌、真菌、原生生物和病毒等病原生物的胁迫.AMPs具有相对分子质量小、两亲性结构和携带正电荷等理化性质.综述抗菌肽构象、电荷及阳离子度、疏水性与疏水力矩、两亲性及其他属性等方面的研究进展.

  20. In vitro phagocytosis and intracellular survival of Campylobacter jejuni with phagocytes

    Energy Technology Data Exchange (ETDEWEB)

    Kiehlbauch, J.A.

    1986-01-01

    In vitro phagocytosis and intracellular survival of Campylobacter jejuni was studied using three types of mononuclear phagocytes: a J774G8 peritoneal macrophage line, resident BABL/c peritoneal macrophages and human peripheral blood monocytes. In phagocytosis assays using CFU determinations, phagocytosis increased steadily over an 8 hr time period. Results obtained using a /sup 51/Cr assay indicated no consistent significant difference between phagocytosis of C. jejuni between the three mononuclear phagocytes or PMN's and that maximum infection occurred prior to 0.5 hr and maintained throughout the 4 hr assay. Further investigation of the mechanism of attachment and entry of C. jejuni revealed this process required the expenditure of energy by the phagocyte, but was not inhibited by inhibitors of microfilament functions. In addition, phagocytosis was enhanced by the presence of 20% FCS,

  1. Factors influencing phagocytosis of Salmonella typhimurium by macrophages in murine schistosomiasis

    Directory of Open Access Journals (Sweden)

    Muniz-Junqueira Maria Imaculada

    1997-01-01

    Full Text Available We investigated the influence of Salmonella typhimurium load and specific antibodies on phagocytosis in schistosomiasis. Macrophages from Schistosoma mansoni-infected mice showed depressed capacity to increase the phagocytosis in the presence of a high bacterial load, due to a reduced involvement of these cells in phagocytosis and to a deficient ability to increase the number of phagocytosed bacteria. Normal and Salmonella-infected mice increased their phagocytic capacity when exposed to a high bacterial load. Antibody to Salmonella increased the phagocytic capacity of macrophages from Schistosoma-infected mice due to an increase in the number of bacteria phagocytosed but caused no modification in the number of macrophages engaged in phagocytosis. Our data indicate that macrophages from Schistosoma-infected mice work close to their functional limit, since no increase in phagocytosis was observed after increasing the bacterial load. Specific antibodies can improve their phagocytic capacity and, therefore, could help clearing concurrent infection.

  2. In vitro phagocytosis of several Candida berkhout species by murine leukocytes.

    Science.gov (United States)

    Fontenla de Petrino, S E; Bibas Bonet de Jorrat, M E; Sirena, A

    1985-03-01

    In vitro phagocytosis of thirteen Candida berkhout species by rat leukocytes was studied to assess a possible correlation between pathogenicity and phagocytosis Yeast-leukocyte suspensions were mixed up for 3 h and phagocytic index, germ-tube formation and leukocyte candidacidal activity were evaluated. Highest values for phagocytosis were reached in all cases at the end of the first hour. Leukocyte candidacidal activity was absent. Only C. albicans produced germ-tubes. The various phagocytosis indices were determined depending on the Candida species assayed. Under these conditions, the more pathogenic species presented the lower indices of phagocytosis. It is determined that the in vitro phagocytic index may bear a close relationship with the pathogenicity of the Candida berkhout.

  3. Antimicrobial polymers.

    Science.gov (United States)

    Jain, Anjali; Duvvuri, L Sailaja; Farah, Shady; Beyth, Nurit; Domb, Abraham J; Khan, Wahid

    2014-12-01

    Better health is basic requirement of human being, but the rapid growth of harmful pathogens and their serious health effects pose a significant challenge to modern science. Infections by pathogenic microorganisms are of great concern in many fields such as medical devices, drugs, hospital surfaces/furniture, dental restoration, surgery equipment, health care products, and hygienic applications (e.g., water purification systems, textiles, food packaging and storage, major or domestic appliances etc.) Antimicrobial polymers are the materials having the capability to kill/inhibit the growth of microbes on their surface or surrounding environment. Recently, they gained considerable interest for both academic research and industry and were found to be better than their small molecular counterparts in terms of enhanced efficacy, reduced toxicity, minimized environmental problems, resistance, and prolonged lifetime. Hence, efforts have focused on the development of antimicrobial polymers with all desired characters for optimum activity. In this Review, an overview of different antimicrobial polymers, their mechanism of action, factors affecting antimicrobial activity, and application in various fields are given. Recent advances and the current clinical status of these polymers are also discussed.

  4. Genome-wide transcriptional changes induced by phagocytosis or growth on bacteria in Dictyostelium

    Directory of Open Access Journals (Sweden)

    Peracino Barbara

    2008-06-01

    Full Text Available Abstract Background Phagocytosis plays a major role in the defense of higher organisms against microbial infection and provides also the basis for antigen processing in the immune response. Cells of the model organism Dictyostelium are professional phagocytes that exploit phagocytosis of bacteria as the preferred way to ingest food, besides killing pathogens. We have investigated Dictyostelium differential gene expression during phagocytosis of non-pathogenic bacteria, using DNA microarrays, in order to identify molecular functions and novel genes involved in phagocytosis. Results The gene expression profiles of cells incubated for a brief time with bacteria were compared with cells either incubated in axenic medium or growing on bacteria. Transcriptional changes during exponential growth in axenic medium or on bacteria were also compared. We recognized 443 and 59 genes that are differentially regulated by phagocytosis or by the different growth conditions (growth on bacteria vs. axenic medium, respectively, and 102 genes regulated by both processes. Roughly one third of the genes are up-regulated compared to macropinocytosis and axenic growth. Functional annotation of differentially regulated genes with different tools revealed that phagocytosis induces profound changes in carbohydrate, aminoacid and lipid metabolism, and in cytoskeletal components. Genes regulating translation and mitochondrial biogenesis are mostly up-regulated. Genes involved in sterol biosynthesis are selectively up-regulated, suggesting a shift in membrane lipid composition linked to phagocytosis. Very few changes were detected in genes required for vesicle fission/fusion, indicating that the intracellular traffic machinery is mostly in common between phagocytosis and macropinocytosis. A few putative receptors, including GPCR family 3 proteins, scaffolding and adhesion proteins, components of signal transduction and transcription factors have been identified, which could

  5. The virulence regulator Sae of Staphylococcus aureus: promoter activities and response to phagocytosis-related signals.

    Science.gov (United States)

    Geiger, Tobias; Goerke, Christiane; Mainiero, Markus; Kraus, Dirk; Wolz, Christiane

    2008-05-01

    The two-component system SaeRS of Staphylococcus aureus is closely involved in the regulation of major virulence factors. However, little is known about the signals leading to saeRS activation. A total of four overlapping transcripts (T1 to T4) from three different transcription starting points are expressed in the sae operon. We used a beta-galactosidase reporter assay to characterize the putative promoter regions within the saeRS upstream region. The main transcript T2 is probably generated by endoribonucleolytic processing of the T1 transcript. Only two distinct promoter elements (P1 and P3) could be detected within the saeRS upstream region. The P3 promoter, upstream of saeRS, generates the T3 transcript, includes a cis-acting enhancer element and is repressed by saeRS. The most distal P1 promoter is strongly autoregulated, activated by agr, and repressed by sigma factor B. In strain Newman a mutation within the histidine kinase SaeS leads to a constitutively activated sae system. Evaluation of different external signals revealed that the P1 promoter in strain ISP479R and strain UAMS-1 is inhibited by low pH and high NaCl concentrations but activated by hydrogen peroxide. The most prominent induction of P1 was observed at subinhibitory concentrations of alpha-defensins in various S. aureus strains, with the exception of strain ISP479R and strain COL. P1 was not activated by the antimicrobial peptides LL37 and daptomycin. In summary, the results indicate that the sensor molecule SaeS is activated by alteration within the membrane allowing the pathogen to react to phagocytosis related effector molecules.

  6. Phagocytosis and killing of Streptococcus suis by porcine neutrophils.

    Science.gov (United States)

    Chabot-Roy, Geneviève; Willson, Philip; Segura, Mariela; Lacouture, Sonia; Gottschalk, Marcelo

    2006-07-01

    Streptococcus suis serotype 2 is an important swine pathogen responsible for diverse infections, mainly meningitis. Virulence factors and the pathogenesis of infection are not well understood. Neutrophils may play an important role in the pathogenesis of infection given that infiltration by neutrophils and mononuclear cells are frequently observed in lesions caused by S. suis. The objective of this work was to study the interactions between S. suis serotype 2 and porcine neutrophils. Results showed that suilysin is toxic to neutrophils and this could help S. suis evade innate immunity. Moreover, suilysin appears to affect complement-dependent killing by decreasing the opsonization of S. suis and the bactericidal capacity of neutrophils. Our results confirm that capsule polysaccharide protects S. suis against killing and phagocytosis by neutrophils. We also showed that the presence of specific IgG against S. suis serotype 2 promoted killing by neutrophils, indicating that the induction of a strong humoral response is beneficial for clearance of this pathogen.

  7. VDRL antibodies enhance phagocytosis of Treponema pallidum by macrophages.

    Science.gov (United States)

    Baker-Zander, S A; Shaffer, J M; Lukehart, S A

    1993-05-01

    Although reactivity in nontreponemal tests develops in patients with untreated syphilis, no immunologic function has been ascribed to these antibodies. This study demonstrates that rabbit antibodies induced by immunization with VDRL antigen and VDRL antibodies affinity-purified from syphilitic rabbit serum enhance phagocytosis of Treponema pallidum. The proportion of macrophages ingesting treponemes in the presence of these antisera was 45% +/- 5% and 27% +/- 4%, respectively, versus 14% +/- 3% for normal serum (P VDRL antibodies from syphilitic serum diminished but did not eliminate opsonization, suggesting at least two classes of target molecules. Despite opsonic capacity, VDRL antibodies fail to facilitate macrophage-mediated killing of T. pallidum. Nevertheless, VDRL-immunized rabbits are partially protected against T. pallidum infection, developing fewer lesions (delayed and smaller) than do unimmunized controls. These results suggest a heretofore unrecognized functional role for VDRL antibodies in syphilis infection.

  8. Leucocyte phagocytosis during the luteal phase in bitches.

    Science.gov (United States)

    Holst, Bodil Ström; Gustavsson, Malin Hagberg; Lilliehöök, Inger; Morrison, David; Johannisson, Anders

    2013-05-15

    Pyometra is a disease that affects a large proportion of intact bitches, and typically is seen during the latter half of dioestrus. Several factors contribute to the development of pyometra, including genetic factors, an infectious component (most often Escherichia coli), and hormonal factors. Hormones may act directly on the endometrium, and also affect the immune system. In dogs, the phagocytic ability has been shown to decrease with age, and ovarian hormones have also been shown to affect immune resistance. The aim of the present study was to examine whether phagocytosis by canine leucocytes varies significantly during the luteal phase. Eight bitches were followed by repeated blood sampling. Samples were taken at the calculated optimal day for mating (Day 1), and thereafter on days 8, 15 and 22 (early luteal phase) and 29, 43, 57 and 71 (late luteal phase). Blood was collected from the cephalic vein into EDTA tubes for leucocyte counts and heparinised tubes for testing of phagocytosis and oxidative burst using commercial kits and flow cytometry. The cell activity of the phagocyting leucocytes, expressed as mean fluorescence activity, MFI, was significantly lower during late luteal phase than during early luteal phase. The proportion of leucocytes that was induced to phagocyte did not differ significantly. The percentage of cells stimulated by E. coli to oxidative burst was significantly lower during late luteal phase. Their activity did not differ between the two periods. The number of cells stimulated to oxidative burst by a low stimulus was too low to evaluate, and leucocytes stimulated with the high stimulus did not vary in oxidative burst between the two periods. The changes in phagocytic activity and in the number of leucocytes that showed oxidative burst were not associated with any change in the proportion of different leucocytes. The decreased phagocytic capacity possibly contributes to the higher incidence of diseases such as pyometra during the latter

  9. Mechanisms associated with phagocytosis of Arcobacter butzleri by Acanthamoeba castellanii.

    Science.gov (United States)

    Medina, Gustavo; Flores-Martin, Sandra; Fonseca, Belchiolina; Otth, Carola; Fernandez, Heriberto

    2014-05-01

    Acanthamoeba castellanii is a free-living amoeba widely found in environmental matrices such as soil and water. Arcobacter butzleri is an emerging potential zoonotic pathogen that can be isolated from environmental water sources, where they can establish endosymbiotic relationships with amoebas. The aim of this study was to describe the implication of mannose-binding proteins and membrane-associated receptors of glucose and galactose present in the amoebic membrane, during the attachment of Arcobacter butzleri by blocking with different saccharides. Another objective was to describe the signaling pathways involved in phagocytosis of these bacteria using specific inhibitors and analyze the implication of phagolysosome formation on the survival of Arcobacter butzleri inside the amoeba. We infer that the attachment of Arcobacter butzleri to the amoeba is a process which involves the participation of mannose-binding proteins and membrane-associated receptors of glucose and galactose present in the amoeba. We also demonstrated an active role of protozoan actin polymerization in the phagocytosis of Arcobacter butzleri and a critical involvement of PI3K and RhoA pathways. Further, we demonstrated that the tyrosine kinase-induced actin polymerization signal is essential in Acanthamoeba-mediated bacterial uptake. Through phagolysosomal formation analysis, we conclude that the survival of Arcobacter butzleri inside the amoeba could be related with the ability to remain inside vacuoles not fused with lysosomes, or with the ability to retard the fusion between these structures. All these results help the understanding of the bacterial uptake mechanisms used by Acanthamoeba castellanii and contribute to evidence of the survival mechanisms of Arcobacter butzleri.

  10. Activated microglia cause reversible apoptosis of pheochromocytoma cells, inducing their cell death by phagocytosis.

    Science.gov (United States)

    Hornik, Tamara C; Vilalta, Anna; Brown, Guy C

    2016-01-01

    Some apoptotic processes, such as phosphatidylserine exposure, are potentially reversible and do not necessarily lead to cell death. However, phosphatidylserine exposure can induce phagocytosis of a cell, resulting in cell death by phagocytosis: phagoptosis. Phagoptosis of neurons by microglia might contribute to neuropathology, whereas phagoptosis of tumour cells by macrophages might limit cancer. Here, we examined the mechanisms by which BV-2 microglia killed co-cultured pheochromocytoma (PC12) cells that were either undifferentiated or differentiated into neuronal cells. We found that microglia activated by lipopolysaccharide rapidly phagocytosed PC12 cells. Activated microglia caused reversible phosphatidylserine exposure on and reversible caspase activation in PC12 cells, and caspase inhibition prevented phosphatidylserine exposur and decreased subsequent phagocytosis. Nitric oxide was necessary and sufficient to induce the reversible phosphatidylserine exposure and phagocytosis. The PC12 cells were not dead at the time they were phagocytised, and inhibition of their phagocytosis left viable cells. Cell loss was inhibited by blocking phagocytosis mediated by phosphatidylserine, MFG-E8, vitronectin receptors or P2Y6 receptors. Thus, activated microglia can induce reversible apoptosis of target cells, which is insufficient to cause apoptotic cell death, but sufficient to induce their phagocytosis and therefore cell death by phagoptosis.

  11. Phagocytosis of gram-negative bacteria by a unique CD14-dependent mechanism.

    Science.gov (United States)

    Schiff, D E; Kline, L; Soldau, K; Lee, J D; Pugin, J; Tobias, P S; Ulevitch, R J

    1997-12-01

    THP-1-derived cell lines were stably transfected with constructs encoding glycophosphatidylinositol (GPI)-anchored or transmembrane forms of human CD14. CD14 expression was associated with enhanced phagocytosis of serum (heat-inactivated)-opsonized Escherichia coli (opEc). Both the GPI-anchored and transmembrane forms of CD14 supported phagocytosis of opEc equally well. Lipopolysaccharide-binding protein (LBP) played a role in CD14-dependent phagocytosis as evidenced by inhibition of CD14-dependent phagocytosis of opEc with anti-LBP monoclonal antibody (mAb) and by enhanced phagocytosis of E. coli opsonized with purified LBP. CD14-dependent phagocytosis was inhibited by a phosphatidylinositol (PI) 3-kinase inhibitor (wortmannin) and a protein tyrosine kinase inhibitor (tyrphostin 23) but not a protein kinase C inhibitor (bisindolyl-maleimide) or a divalent cation chelator (ethylenediaminetetraacetate). Anti-LBP mAb 18G4 and anti-CD14 mAb 18E12 were used to differentiate between the pathways involved in CD14-dependent phagocytosis and CD14-dependent cell activation. F(ab')2 fragments of 18G4, a mAb to LBP that does not block cell activation, inhibited ingestion of opEc by THP1-wtCD14 cells. 18E12 (an anti-CD14 mAb that does not block LPS binding to CD14 but does inhibit CD14-dependent cell activation) did not inhibit phagocytosis of LBP-opEc by THP1-wtCD14 cells. Furthermore, CD14-dependent phagocytosis was not inhibited by anti-CD18 (CR3 and CR4 beta-chain) or anti-Fcgamma receptor mAb.

  12. Animation of Antimicrobial Resistance

    Science.gov (United States)

    ... Veterinary Safety & Health Antimicrobial Resistance Animation of Antimicrobial Resistance Share Tweet Linkedin Pin it More sharing options ... produced a nine-minute animation explaining how antimicrobial resistance both emerges and proliferates among bacteria. Over time, ...

  13. Animation of Antimicrobial Resistance

    Medline Plus

    Full Text Available ... Veterinary Home Animal & Veterinary Safety & Health Antimicrobial Resistance Animation of Antimicrobial Resistance Share Tweet Linkedin Pin it ... Veterinary Medicine is cited as the corporate author. Animation Animation of Antimicrobial Resistance (WMV - 19.2MB) 9: ...

  14. Animation of Antimicrobial Resistance

    Medline Plus

    Full Text Available ... how antimicrobial resistance both emerges and proliferates among bacteria. Over time, the use of antimicrobial drugs will result in the development of resistant strains of bacteria, complicating clinician's efforts to select the appropriate antimicrobial ...

  15. Animation of Antimicrobial Resistance

    Medline Plus

    Full Text Available ... how antimicrobial resistance both emerges and proliferates among bacteria. Over time, the use of antimicrobial drugs will result in the development of resistant strains of bacteria, complicating clinician's efforts to select the appropriate antimicrobial ...

  16. Animation of Antimicrobial Resistance

    Medline Plus

    Full Text Available ... Veterinary Home Animal & Veterinary Safety & Health Antimicrobial Resistance Animation of Antimicrobial Resistance Share Tweet Linkedin Pin it ... Veterinary Medicine is cited as the corporate author. Animation Animation of Antimicrobial Resistance (WMV - 19.2MB) 9: ...

  17. Animation of Antimicrobial Resistance

    Medline Plus

    Full Text Available ... Animal & Veterinary Safety & Health Antimicrobial Resistance Animation of Antimicrobial Resistance Share Tweet Linkedin Pin it More sharing options ... CVM) produced a nine-minute animation explaining how antimicrobial resistance both emerges and proliferates among bacteria. Over time, ...

  18. Research progress on antimicrobial effect of denture soft liner and maxillofacial prosthesis silicone rubher%义齿软衬和赝复体硅橡胶抗菌性的研究进展

    Institute of Scientific and Technical Information of China (English)

    杨活川

    2011-01-01

    Silicone rubber is widely used in oral maxillofacial prosthesis and denture soft lining, because of its good physical, chemical, and biological properties. The low toxicity and surface porosity of silicone rubber provide a good condition for the proliferation of bacteria in oral environment. The adherence of bacteria, especially Candida albicans, can accelerate the aging and coloration of the material, affecting the esthetics and lowing the useful life of material, even cause denture stomatitis. So the research of antimicrobial effect of silicone rubber is one of the focuses in recent years. This paper summarized the current progress on the antimicrobial effect of denture soft liner and maxillofacial prosthesis silicone rubber.%硅橡胶材料以其良好的物理、化学、生物性能在口腔颌面赝复修复和义齿软衬等方面得到了越来越多的应用.因其对组织毒性小,表面呈多孔性,在口腔环境中给微生物的滋生提供了有利条件.微生物特别是白色假丝酵母菌的黏附可加速材料的老化、着色,影响美观,使材料物理性能发生改变,降低材料的使用寿命,甚至导致义齿性口炎的发生,故硅橡胶的抗菌性研究成为近年来国内外学者的研究热点之一.本文将针对硅橡胶义齿软衬和赝复体材料的抗菌性作一综述.

  19. Research progress in antibacterial mechanisms of antimicrobial peptides%抗菌肽抗菌机制的研究进展

    Institute of Scientific and Technical Information of China (English)

    孙红; 薛越; 黄宁

    2013-01-01

    Antimicrobial peptides(AMPs),a kind of small peptides which widely exist in many organisms,are an important component of the innate immune system.They can not only effectively defense against bacteria,but also fungi,viruses,parasites and even cancer cells.With the properties of rapid microbicidal action,broad-specutrum activity,uneasy to develop drug resistance and others,AMPs have been the research focus of medicine,livestock and aquaculture at present.In this paper,the antibacterial mechanisms of AMPs are reviewed.%抗菌肽是广泛存在于生物体内的一类小分子多肽,是生物固有免疫系统的重要组成部分.抗菌肽不仅能够有效杀灭细菌,而且还对真菌、病毒、寄生虫甚至肿瘤细胞都具有一定的杀伤作用.抗菌肽因其作用迅速、广谱抗菌、不易产生耐药性等诸多特点,已成为医药卫生、畜牧养殖、水产动物等领域研究的热点.本文就当前抗菌肽抗菌机制的研究进展作一综述.

  20. Animation of Antimicrobial Resistance

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    Full Text Available ... More in Antimicrobial Resistance National Antimicrobial Resistance Monitoring ... Note: If you need help accessing information in different file formats, see Instructions for Downloading ...

  1. Animation of Antimicrobial Resistance

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    Full Text Available ... More in Antimicrobial Resistance National Antimicrobial Resistance Monitoring ... Note: If you need help accessing information in different file formats, see Instructions for Downloading ...

  2. Animation of Antimicrobial Resistance

    Science.gov (United States)

    ... Animal & Veterinary Cosmetics Tobacco Products Animal & ... antimicrobial resistance both emerges and proliferates among bacteria. Over time, the use of antimicrobial drugs will result in the development ...

  3. The cationic peptide LL-37 binds Mac-1 (CD11b/CD18) with a low dissociation rate and promotes phagocytosis.

    Science.gov (United States)

    Zhang, Xianwei; Bajic, Goran; Andersen, Gregers R; Christiansen, Stig Hill; Vorup-Jensen, Thomas

    2016-05-01

    As a broad-spectrum anti-microbial peptide, LL-37 plays an important role in the innate immune system. A series of previous reports implicates LL-37 as an activator of various cell surface receptor-mediated functions, including chemotaxis in integrin CD11b/CD18 (Mac-1)-expressing cells. However, evidence is scarce concerning the direct binding of LL-37 to these receptors and investigations on the associated binding kinetics is lacking. Mac-1, a member of the β2 integrin family, is mainly expressed in myeloid leukocytes. Its critical functions include phagocytosis of complement-opsonized pathogens. Here, we report on interactions of LL-37 and its fragment FK-13 with the ligand-binding domain of Mac-1, the α-chain I domain. LL-37 bound the I-domain with an affinity comparable to the complement fragment C3d, one of the strongest known ligands for Mac-1. In cell adhesion assays both LL-37 and FK-13 supported binding by Mac-1 expressing cells, however, with LL-37-coupled surfaces supporting stronger cell adhesion than FK-13. Likewise, in phagocytosis assays with primary human monocytes both LL-37 and FK-13 enhanced uptake of particles coupled with these ligands but with a tendency towards a stronger uptake by LL-37.

  4. TI-VAMP/VAMP7 is required for optimal phagocytosis of opsonised particles in macrophages.

    Science.gov (United States)

    Braun, Virginie; Fraisier, Vincent; Raposo, Graça; Hurbain, Ilse; Sibarita, Jean-Baptiste; Chavrier, Philippe; Galli, Thierry; Niedergang, Florence

    2004-10-27

    Phagocytosis relies on extension of plasmalemmal pseudopods generated by focal actin polymerisation and delivery of membranes from intracellular pools. Here we show that compartments of the late endocytic pathway, bearing the tetanus neurotoxin-insensitive vesicle-associated membrane protein (TI-VAMP/VAMP7), are recruited upon particle binding and undergo exocytosis before phagosome sealing in macrophages during Fc receptor (FcR)-mediated phagocytosis. Expression of the dominant-negative amino-terminal domain of TI-VAMP or depletion of TI-VAMP with small interfering RNAs inhibited phagocytosis mediated by Fc or complement receptors. In addition, inhibition of TI-VAMP activity led to a reduced exocytosis of late endocytic vesicles and this resulted in an early blockade of pseudopod extension, as observed by scanning electron microscopy. Therefore, TI-VAMP defines a new pathway of membrane delivery required for optimal FcR-mediated phagocytosis.

  5. Phagocytosis mediates specificity in the immune defence of an invertebrate, the woodlouse Porcellio scaber (Crustacea: Isopoda).

    Science.gov (United States)

    Roth, Olivia; Kurtz, Joachim

    2009-11-01

    Specificity and memory are the hallmarks of the adaptive immune system of vertebrates. However, phenomena of specificity upon priming of immunity have recently been demonstrated also in invertebrates, which rely exclusively on innate immune defence. It has been suggested that phagocytosis might represent a core candidate for such specificity in invertebrates. We here developed in vitro phagocytosis measurements for different bacteria in the woodlouse Porcellio scaber (Crustacea: Isopoda). After immune priming with heat-killed bacteria, hemocytes showed increased phagocytosis of a previously encountered bacterial strain compared to other bacteria. These data support the role of phagocytosis in invertebrate immunological specificity and suggest a high degree of specificity that even enables to differentiate between strains of the same bacterial species.

  6. Bacterial and strain specificities in opsonization, phagocytosis and killing of Streptococcus mutans.

    Science.gov (United States)

    Scully, C M; Lehner, T

    1979-01-01

    Opsonization of Streptococcus mutans, followed by phagocytosis and killing by polymorphonuclear leucocytes has been postulated as an effector mechanism in protection against dental caries. Opsonization was studied by using sera from monkeys immunized with killed Strep. mutans (sero-type c) and compared with sera from sham-immunized monkeys. Antibodies to Strep. mutans (sero-type c) induced maximal phagocytosis and killing of serotypes c and e, and this was significantly greater than with serotypes a and d; there was no significant phagocytosis or killing of serotype b. There was little or no opsonization with Actinomyces viscosus, Lactobacillus casei, Strep, sanguis and Strep. salivarius. The exception was Strep. CHT which showed significant phagocytosis and killing. The results suggest that immunization with the serotype c strain of Strep. mutans might offer protection against four of the five common serotypes of this organism.

  7. Research progress on anti-inflammatory action of antimicrobial peptides in vivo%抗菌肽体内抗炎作用的研究进展

    Institute of Scientific and Technical Information of China (English)

    许银叶; 褚夫江; 朱家勇

    2013-01-01

    抗菌肽是生物体内组成性或诱导性表达的一类小分子多肽,是机体防御系统的重要组成部分.抗菌肽不仅具有广谱杀菌能力,还具有抗真菌、抗病毒、抗寄生虫等生物活性.抗菌肽体外的抗炎作用已经研究较多,但其在体内的抗炎作用才逐渐引起学者的关注.抗菌肽对炎症的调节是多方面的,主要通过抑制生物性致炎因子的生长、调节炎症相关信号通路及其转录因子的表达、调节免疫活性以及中和LPS等,从而发挥抗炎作用.本文就抗菌肽在体内抗炎作用的研究进展作一综述.%Antimicrobial peptides (AMPs), a family of small polypeptides which are produced by constitutive or inducible expression in organisms, are key components of host defense system. Besides broad -spectrum antibacterial activity, AMPs also have many biological activities against fungi, virus and parasites. The anti -inflammatory action of AMPs in vitro has been studied widely, but their in vivo action attracts attention until now. AMPs regulate inflammation in vivo by many ways, such as regulating the expression of inflammation -related signaling pathways and transcription factors, inhibiting the growth of biological inflammatory cytokines, modulating the immune activity and neutralizing lipopolysaccharide (LPS). In this paper, we summarized the anti-inflammatory action of AMPs in vivo.

  8. The importance of surfactant proteins-New aspects on macrophage phagocytosis.

    Science.gov (United States)

    Tschernig, Thomas; Veith, Nils T; Diler, Ebru; Bischoff, Markus; Meier, Carola; Schicht, Martin

    2016-11-01

    Surfactant and its components have multiple functions. The so called collectins are surfactant proteins which opsonize bacteria and improve pulmonary host defense via the phagocytosis and clearance of microorganisms and particles. In this special issue of the Annals of Anatomy a new surfactant protein, Surfactant Associated 3, is highlighted. As outlined in this mini review Surfactant Associated 3 is regarded as an enhancer of phagocytosis. In addition, the role played by SP-A is updated and open research questions raised.

  9. Treatment of serum with supernatants from cultures of Candida albicans reduces its serum-dependent phagocytosis

    Directory of Open Access Journals (Sweden)

    Santos Aderbal Antonio dos

    2002-01-01

    Full Text Available Candida albicans is a potent activator of the complement system, and heat labile opsonins produced by activation of C3 (C3b and iC3b enhance phagocytosis of C. albicans mediated by complement receptors. In this study we treated mouse serum with supernatants from cultures of a protease producer strain of C. albicans and evaluated the ability of this serum to enhance phagocytosis of C. albicans. Cell-free supernatants from cultures of C. albicans were concentrated 5 fold and added to mouse serum for 30 min at 37ºC, before using this serum for opsonization of glutaraldehyde-fixed yeast cells. We observed that normal mouse serum increased about 3 fold the phagocytosis of C. albicans by mice peritoneal macrophages, whereas supernatant-treated serum did not increase phagocytosis. This effect of supernatants on serum was prevented by addition of pepstatin (5 µg/ ml; an inhibitor of C. albicans acid proteases to the medium. Serum treated with supernatants from cultures of a protease-deficient mutant of C. albicans also increased about 3 fold phagocytosis of the yeast. These results suggest that a protease produced by C. albicans causes proteolysis of serum opsonins, thereby reducing the phagocytosis of the yeast.

  10. Mechanism involved in interleukin-21-induced phagocytosis in human monocytes and macrophages.

    Science.gov (United States)

    Vallières, F; Girard, D

    2017-02-01

    The interleukin (IL)-21/IL-21 receptor (R) is a promising system to be exploited for the development of therapeutic strategies. Although the biological activities of IL-21 and its cell signalling events have been largely studied in immunocytes, its interaction with human monocytes and macrophages have been neglected. Previously, we reported that IL-21 enhances Fc gamma receptor (FcRγ)-mediated phagocytosis in human monocytes and in human monocyte-derived macrophages (HMDM) and identified Syk as a novel molecular target of IL-21. Here, we elucidate further how IL-21 promotes phagocytosis in these cells. Unlike its ability to enhance phagocytosis of opsonized sheep red blood cells (SRBCs), IL-21 did not promote phagocytosis of Escherichia coli and zymosan by monocytes and did not alter the cell surface expression of CD16, CD32 and CD64. In HMDM, IL-21 was found to enhance phagocytosis of zymosan. In addition, we found that IL-21 activates p38, protein kinase B (Akt), signal transducer and activator of transcription (STAT)-1 and STAT-3 in monocytes and HMDM. Using a pharmacological approach, we demonstrate that IL-21 enhances phagocytosis by activating some mitogen-activated protein kinases (MAPKs) and phosphoinositide 3-kinase (PI3K)-Akt and Janus kinase (JAK)-STAT pathways. These results obtained in human monocytes and macrophages have to be considered for a better exploitation of the IL-21/IL-21R system for therapeutic purposes. © 2016 British Society for Immunology.

  11. Phagocytosis of IgA Immune Complexes by Human U937 Cells

    Institute of Scientific and Technical Information of China (English)

    郭彩云; 崔薇; 张伟

    2003-01-01

    In order to study FcαR Ⅰ mediated phagocytosis ot lgA immune complexes by U937 cells, antigen 8.9NIP/BSA was labeled with FITC and reacted with anti-NIP IgA or anti-NIP IgG antibody to form immune complexes (ICs). They were then incubated with phorbol 12-myristate B-acetate (PMA) stimulated U937 cells. The phagocytosed ICs were quantified by flow cytometry. The results was that the expression of FcαR Ⅰ on U937 cells was higher than that of FcγR Ⅰ , FcyR Ⅱ and FcγR Ⅲ. After stimulation by PMA, expression of FcαR Ⅰ on U937 cells was markedly upregulated and the phagocytosis of IgA ICs was enhanced. FcαR Ⅰ mediated specific IgA phagocytosis was stronger than FcγR Ⅰ and FcγR Ⅱ mediated IgG phagocytosis. Complement receptors, CR1 and CR3, enhanced U937 cell phagocytosis of IgA ICs. It concludes that FcγR Ⅰ mediated strong phagocytosis of IgA ICs.

  12. Fc-receptor-mediated phagocytosis is regulated by mechanical properties of the target

    Science.gov (United States)

    Beningo, Karen A.; Wang, Yu-li

    2002-01-01

    Phagocytosis is an actin-based process used by macrophages to clear particles greater than 0.5 microm in diameter. In addition to its role in immunological responses, phagocytosis is also necessary for tissue remodeling and repair. To prevent catastrophic autoimmune reactions, phagocytosis must be tightly regulated. It is commonly assumed that the recognition/selection of phagocytic targets is based solely upon receptor-ligand binding. Here we report an important new criterion, that mechanical parameters of the target can dramatically affect the efficiency of phagocytosis. When presented with particles of identical chemical properties but different rigidity, macrophages showed a strong preference to engulf rigid objects. Furthermore, phagocytosis of soft particles can be stimulated with the microinjection of constitutively active Rac1 but not RhoA, and with lysophosphatidic acid, an agent known to activate the small GTP-binding proteins of the Rho family. These data suggest a Rac1-dependent mechanosensory mechanism for phagocytosis, which probably plays an important role in a number of physiological and pathological processes from embryonic development to autoimmune diseases.

  13. Responses of macrophages against Salmonella infection compared with phagocytosis.

    Science.gov (United States)

    Hu, Maozhi; Yang, Yun; Meng, Chuang; Pan, Zhiming; Jiao, Xinan

    2013-12-01

    To explore the responses of host cell after infection with live Salmonella compared with phagocytosis to dead bacteria, the responses of mouse macrophage after infection with Salmonella enteritidis C50041 and the fixed C50041 (C50041-d) were analyzed. Results indicated that the cytotoxicity induced by C50041 was stronger than C50041-d. Similar changing trends of mitochondrial membrane potential, intracellular concentration of calcium ions, reactive oxygen species and nitric oxide were found between C50041 and C50041-d infection. But the cell responses against C50041 were earlier and stronger than C50041-d. LC3 expression of macrophage induced by C50041 was lower than C50041-d. C50041 significantly inhibited the production of tumor necrosis factor and interleukin (IL)-6. Whereas intracellular caspase-1 activation and IL-1β release induced by C50041 were stronger than C50041-d, caspase-1 activation and IL-1β release are the innate defense responses of macrophage. Therefore, it will be beneficial to explore the use of this pathway in the control of Salmonella infection.

  14. Human CD14 mediates recognition and phagocytosis of apoptotic cells.

    Science.gov (United States)

    Devitt, A; Moffatt, O D; Raykundalia, C; Capra, J D; Simmons, D L; Gregory, C D

    1998-04-02

    Cells undergoing programmed cell death (apoptosis) are cleared rapidly in vivo by phagocytes without inducing inflammation. Here we show that the glycosylphosphatidylinositol-linked plasma-membrane glycoprotein CD14 on the surface of human macrophages is important for the recognition and clearance of apoptotic cells. CD14 can also act as a receptor that binds bacterial lipopolysaccharide (LPS), triggering inflammatory responses. Overstimulation of CD14 by LPS can cause the often fatal toxic-shock syndrome. Here we show that apoptotic cells interact with CD14, triggering phagocytosis of the apoptotic cells. This interaction depends on a region of CD14 that is identical to, or at least closely associated with, a region known to bind LPS. However, apoptotic cells, unlike LPS, do not provoke the release of pro-inflammatory cytokines from macrophages. These results indicate that clearance of apoptotic cells is mediated by a receptor whose interactions with 'non-self' components (LPS) and 'self' components (apoptotic cells) produce distinct macrophage responses.

  15. Immunomodulation by gadolinium chloride-induced Kupffer cell phagocytosis blockade

    Energy Technology Data Exchange (ETDEWEB)

    Lazar, G.; Husztik, E.; Kiss, I.; Szakacs, J. [Albert Szent-Gyoergyi Medical Univ., Szeged (Hungary). Inst. of Pathophysiology; Lazar, G. Jr. [Department of Surgery, Albert Szent-Gyoergyi Medical University, PO Box 531, 6701 Szeged (Hungary); Olah, J. [Department of Dermatology, Albert Szent-Gyoergyi Medical University, PO Box 531, 6701 Szeged (Hungary)

    1998-07-24

    Gadolinium chloride (GdCl{sub 3}), a rare earth metal salt, depresses macrophage activity, and is commonly used to study the physiology of the reticuloendothelial system. In the present work, the effect of GdCl{sub 3}-induced Kupffer cell blockade on the humoral immune response in mice to sheep red blood cells (SRBC) was investigated. Kupffer cell phagocytosis blockade was found to increase both the primary and secondary immune responses to SRBC. The primary immune response was significantly augmented in animals injected intravenously with GdCl{sub 3} 2, 3 or 4 days before injection of the cellular antigen, but GdCl{sub 3} injected 7 days before the antigen did not modify the immune response. Increased secondary humoral immune responses were also observed. When GdCl{sub 3} was injected 2 days before the second dose of antigen, the numbers of both IgM and IgG-producing plaque forming cells were augmented. GdCl{sub 3} injected 2 days before the first dose of SRBC did not modify the humoral immune response. Earlier studies with {sup 51}Cr-labelled foreign red blood cells suggested that the augmentation of the humoral immune response in GdCl{sub 3}-pretreated mice is a consequence of the spillover of the antigen from the liver into the spleen and other extrahepatic reticuloendothelial organs. (orig.) 15 refs.

  16. 可食性降解抗菌保鲜膜的研究进展%The research progress of edible preservative films with biodegradable and antimicrobial features

    Institute of Scientific and Technical Information of China (English)

    周三九; 李月明; 韩德权; 杜易阳; 于艳梅; 李迪; 孙庆申

    2014-01-01

    食品贮藏过程中微生物引起的腐败是影响食品货架期的最重要的因素之一。为此,作为食品流通领域的重要成员,食品包装材料不仅应具有美观商品、便于运输等优点,对一些包装材料还要求具有抗菌、延长食品货架期的功能,并且本身具有安全性和可食用性,这就推动了人们对食品抗菌保鲜膜领域的研究。本文主要介绍了可食性、可降解性(抗菌)保鲜膜的概念、种类(多糖类、蛋白质类、脂类、复合膜类),抗菌剂的种类(有机抗菌剂、无机抗菌剂、天然抗菌剂、细菌素等);阐述了可食性、可降解抗菌保鲜膜的国内外研究现状;展望了可食性降解抗菌保鲜膜的未来发展趋势。本文期望为抗菌保鲜膜领域的研究提供一些新的思路。%Food spoilage caused by microorganisms during food storage is one of the most factors affecting the shelf life of the food. Therefore, as an important member in food circulation process, food packaging materials should not only beautify merchandise, facilitate to transport, etc., for some packaging materials, anti-bacterial and extend food shelf life functions are also required, in addition to the safety and edible features, which promoted the study on food preservative films with antibacterial features. This review stated the concept and types of edible and biodegradable (antibacterial) preservative films (polysaccharides, proteins, lipids, and two or more of them compound-based films), the type of antibacterial agent (organic, inorganic, natural antibacterial agents, bacteriocins, etc.). The research status and prospect of future development trends of the preservative films with antimicrobial, edible, and biodegradable were also stated. This article aimed to provide some new ideas for the research in the field of antibacterial and preservative films.

  17. Neutrophils and intracellular pathogens: beyond phagocytosis and killing.

    Science.gov (United States)

    Appelberg, Rui

    2007-02-01

    Neutrophils are not simply scavenging phagocytes that clear extracellular spaces of rapidly proliferating microbes; they are also active in the control of infections by intracellular pathogens. Several mechanisms for nonphagocytic roles of neutrophils in protective immunity have been put forth over the years but further evidence has recently been accumulating at an increasing pace. In this review, I present the evidence that suggests neutrophils are involved in pathogen shuttling into the lymphoid tissues, in antigen presentation, and in early T cell recruitment and initiation of granuloma organization. Also, a clearer view on the antimicrobial molecules that can be acquired by macrophages to enhance their antimicrobial activity is now emerging. Finally, neutrophils can adversely affect immunity against certain parasites by causing immune deviation.

  18. Antimicrobial resistance

    DEFF Research Database (Denmark)

    Llor, Carl; Bjerrum, Lars

    2014-01-01

    -the-counter sale of antibiotics, the use of antimicrobial stewardship programmes, the active participation of clinicians in audits, the utilization of valid rapid point-of-care tests, the promotion of delayed antibiotic prescribing strategies, the enhancement of communication skills with patients with the aid...... is associated with an increased risk of adverse effects, more frequent re-attendance and increased medicalization of self-limiting conditions. Antibiotic overprescribing is a particular problem in primary care, where viruses cause most infections. About 90% of all antibiotic prescriptions are issued by general...... practitioners, and respiratory tract infections are the leading reason for prescribing. Multifaceted interventions to reduce overuse of antibiotics have been found to be effective and better than single initiatives. Interventions should encompass the enforcement of the policy of prohibiting the over...

  19. Abl family kinases regulate FcγR-mediated phagocytosis in murine macrophages.

    Science.gov (United States)

    Greuber, Emileigh K; Pendergast, Ann Marie

    2012-12-01

    Phagocytosis of Ab-coated pathogens is mediated through FcγRs, which activate intracellular signaling pathways to drive actin cytoskeletal rearrangements. Abl and Arg define a family of nonreceptor tyrosine kinases that regulate actin-dependent processes in a variety of cell types, including those important in the adaptive immune response. Using pharmacological inhibition as well as dominant negative and knockout approaches, we demonstrate a role for the Abl family kinases in phagocytosis by macrophages and define a mechanism whereby Abl kinases regulate this process. Bone marrow-derived macrophages from mice lacking Abl and Arg kinases exhibit inefficient phagocytosis of sheep erythrocytes and zymosan particles. Treatment with the Abl kinase inhibitors imatinib and GNF-2 or overexpression of kinase-inactive forms of the Abl family kinases also impairs particle internalization in murine macrophages, indicating Abl kinase activity is required for efficient phagocytosis. Further, Arg kinase is present at the phagocytic cup, and Abl family kinases are activated by FcγR engagement. The regulation of phagocytosis by Abl family kinases is mediated in part by the spleen tyrosine kinase (Syk). Loss of Abl and Arg expression or treatment with Abl inhibitors reduced Syk phosphorylation in response to FcγR ligation. The link between Abl family kinases and Syk may be direct, as purified Arg kinase phosphorylates Syk in vitro. Further, overexpression of membrane-targeted Syk in cells treated with Abl kinase inhibitors partially rescues the impairment in phagocytosis. Together, these findings reveal that Abl family kinases control the efficiency of phagocytosis in part through the regulation of Syk function.

  20. Knockdown of Five Genes Encoding Uncharacterized Proteins Inhibits Entamoeba histolytica Phagocytosis of Dead Host Cells.

    Science.gov (United States)

    Sateriale, Adam; Miller, Peter; Huston, Christopher D

    2016-04-01

    Entamoeba histolytica is the protozoan parasite that causes invasive amebiasis, which is endemic to many developing countries and characterized by dysentery and liver abscesses. The virulence of E. histolytica correlates with the degree of host cell engulfment, or phagocytosis, and E. histolytica phagocytosis alters amebic gene expression in a feed-forward manner that results in an increased phagocytic ability. Here, we used a streamlined RNA interference screen to silence the expression of 15 genes whose expression was upregulated in phagocytic E. histolytica trophozoites to determine whether these genes actually function in the phagocytic process. When five of these genes were silenced, amebic strains with significant decreases in the ability to phagocytose apoptotic host cells were produced. Phagocytosis of live host cells, however, was largely unchanged, and the defects were surprisingly specific for phagocytosis. Two of the five encoded proteins, which we named E. histolytica ILWEQ (EhILWEQ) and E. histolytica BAR (EhBAR), were chosen for localization via SNAP tag labeling and localized to the site of partially formed phagosomes. Therefore, both EhILWEQ and EhBAR appear to contribute to E. histolytica virulence through their function in phagocytosis, and the large proportion (5/15 [33%]) of gene-silenced strains with a reduced ability to phagocytose host cells validates the previously published microarray data set demonstrating feed-forward control of E. histolytica phagocytosis. Finally, although only limited conclusions can be drawn from studies using the virulence-deficient G3 Entamoeba strain, the relative specificity of the defects induced for phagocytosis of apoptotic cells but not healthy cells suggests that cell killing may play a rate-limiting role in the process of Entamoeba histolytica host cell engulfment.

  1. Knockdown of Five Genes Encoding Uncharacterized Proteins Inhibits Entamoeba histolytica Phagocytosis of Dead Host Cells

    Science.gov (United States)

    Sateriale, Adam; Miller, Peter

    2016-01-01

    Entamoeba histolytica is the protozoan parasite that causes invasive amebiasis, which is endemic to many developing countries and characterized by dysentery and liver abscesses. The virulence of E. histolytica correlates with the degree of host cell engulfment, or phagocytosis, and E. histolytica phagocytosis alters amebic gene expression in a feed-forward manner that results in an increased phagocytic ability. Here, we used a streamlined RNA interference screen to silence the expression of 15 genes whose expression was upregulated in phagocytic E. histolytica trophozoites to determine whether these genes actually function in the phagocytic process. When five of these genes were silenced, amebic strains with significant decreases in the ability to phagocytose apoptotic host cells were produced. Phagocytosis of live host cells, however, was largely unchanged, and the defects were surprisingly specific for phagocytosis. Two of the five encoded proteins, which we named E. histolytica ILWEQ (EhILWEQ) and E. histolytica BAR (EhBAR), were chosen for localization via SNAP tag labeling and localized to the site of partially formed phagosomes. Therefore, both EhILWEQ and EhBAR appear to contribute to E. histolytica virulence through their function in phagocytosis, and the large proportion (5/15 [33%]) of gene-silenced strains with a reduced ability to phagocytose host cells validates the previously published microarray data set demonstrating feed-forward control of E. histolytica phagocytosis. Finally, although only limited conclusions can be drawn from studies using the virulence-deficient G3 Entamoeba strain, the relative specificity of the defects induced for phagocytosis of apoptotic cells but not healthy cells suggests that cell killing may play a rate-limiting role in the process of Entamoeba histolytica host cell engulfment. PMID:26810036

  2. Janus-faced microglia: beneficial and detrimental consequences of microglial phagocytosis

    Directory of Open Access Journals (Sweden)

    Amanda eSierra

    2013-01-01

    Full Text Available Microglia are the resident brain macrophages and they have been traditionally studied as orchestrators of the brain inflammatory response during infections and disease. In addition, microglia has a more benign, less explored role as the brain professional phagocytes. Phagocytosis is a term coined from the Greek to describe the receptor-mediated engulfment and degradation of dead cells and microbes. In addition, microglia phagocytoses brain-specific cargo, such as axonal and myelin debris in spinal cord injury or multiple sclerosis, amyloid-beta deposits in Alzheimer’s disease, and supernumerary synapses in postnatal development. Common mechanisms of recognition, engulfment and degradation of the different types of cargo are assumed, but very little is known about the shared and specific molecules involved in the phagocytosis of each target by microglia. More importantly, the functional consequences of microglial phagocytosis remain largely unexplored. Overall, phagocytosis is considered a beneficial phenomenon, since it eliminates dead cells and induces an anti-inflammatory response. However, phagocytosis can also activate the respiratory burst, which produces toxic reactive oxygen species. Phagocytosis has been traditionally studied in pathological conditions, leading to the assumption that microglia have to be activated in order to become efficient phagocytes. Recent data, however, has shown that unchallenged microglia phagocytose apoptotic cells during development and in adult neurogenic niches, suggesting an overlooked role in brain remodeling throughout the normal lifespan. The present review will summarize the current state of the literature regarding the role of microglial phagocytosis in maintaining tissue homeostasis in health as in disease.

  3. Impact of Hyperbaric Oxygenation on the Phagocytosis-Stimulating Function of the Operated Liver

    Directory of Open Access Journals (Sweden)

    P. N. Savilov

    2008-01-01

    Full Text Available Objective: to study the ability of hyperbaric oxygenation (HBO to eliminate impaired phagocytosis-stimulating hepatic function caused by hepatectomy (HE. Material and methods. Experiments were conducted on 82 outbred female albino rats exposed to HE (15—20% of the organ mass and HBO at 3 ata for 50 min once daily three times within the first three days after surgery. The capacities of neutrophils and monocytes of arterial (aorta and venous (portal vein, hepatic veins blood to ingest and digest S.aureus were investigated. Results: Under HBO, the inhibitory impact of HE on the phagocytosis-stimulating ability of the liver to S.aureus was limited for neutrophils and completely precluded for monocytes. In the posthyperoxic period, the phagocytosis-stimulating function of the operated liver was found to be active against the microbe being examined for both types of phagocytes. This was attended by inhibition of the anhepatic mechanisms responsible for the amplified phagocytic activity of neutrophils and monocytes, which were triggered in HE. HBO selectively regulated the arterial and venous blood content of neutrophils, by ingesting and digesting S.aureus as much as possible. HBO prevented the post-HE delay of the neutrophils and monocytes which actively englobed S.aureus in the operated organ. Conclusion: HBO eliminates HE-induced impairment of phagocytosis-stimulating function of the liver and creates conditions for its delayed activation by day 11 posthy-peroxia. Key words: hyperoxia, phagocytosis, regulation, liver, resection.

  4. Analysis of the dynamic energy flow associated with phagocytosis of bacteria

    Directory of Open Access Journals (Sweden)

    Paul Okpala

    2015-09-01

    Full Text Available This paper treats the phenomenon of phagocytosis from the flow of energy point of view. Considerable efforts have been made towards elucidating the subject of phagocytosis in other fields of learning, but little has been said about the mechanical work that is done during phagocytosis. Phagocytosis without doubt is an interaction that involves the flow of energy. Energy equation model of phagocytosis is then presented in this paper to analyze the mechanical energy that is involved in the build-up of the engulfment of bacteria by the phagocytes. Data of the E Coli bacteria from published work was then applied to the solution of the energy equation. A borderline contact angle ϑ of 77.356° between the phagocyte and the bacteria at χ=0 was deduced in this work. It was shown that when ϑ77.356°, χ>0, engulfment is not favoured for E-coli. This condition is conceptually in line with ΔFNET approach reported in the literature. Data of four different bacterial species were also used to plot the graphs of the engulfment parameter χ against contact angle ϑ which revealed that the more hydrophobic bacteria are easily phagocytized than the more hydrophilic ones.

  5. The Scottish approach to enhancing antimicrobial stewardship.

    Science.gov (United States)

    Nathwani, Dilip; Christie, Peter

    2007-08-01

    In 2002, the Scottish Executive produced the Antimicrobial Resistance Strategy and Scottish Action Plan, which highlighted antimicrobial stewardship as a key objective in combating resistance. An important response, as a part of the Ministerial Healthcare Associated Infection Task Force work programme was the publication of 'Antimicrobial Prescribing Policy and Practice in Scotland: recommendations for good antimicrobial practice in acute hospitals' in 2005. This article briefly reviews the core components of the Scottish approach, reviews progress with some key goals and explores how many of these goals are being taken forward through a cohesive Scottish national multifaceted strategy, which incorporates primary and secondary care. Much of this will spring from the current review of the Scottish Action Plan. While recognizing the significant progress achieved by the Appropriate Antimicrobial Prescribing for Tomorrow's Doctors Project Group in the education of undergraduate medical students, the article also reviews the NHS Education Scotland-supported Scottish National Antimicrobial Prescribing Project, aimed at foundation training doctors in Scotland. We hope that this experience can be shared and further developed with colleagues within the United Kingdom and European Union.

  6. Involvement of myosin VI immunoanalog in pinocytosis and phagocytosis in Amoeba proteus.

    Science.gov (United States)

    Sobczak, Magdalena; Wasik, Anna; Kłopocka, Wanda; Redowicz, Maria Jolanta

    2008-12-01

    Recently, we found a 130-kDa myosin VI immunoanalog in amoeba, which bound to actin in an ATP-sensitive manner and in migrating amoebae colocalized to filamentous actin and dynamin II-containing vesicular structures. To further characterize this protein, we assessed its involvement in amoeba pinocytosis and phagocytosis. Confocal immunofluorescence microscopy and electron microscopy of immunogold-stained cells revealed that, in pinocytotic and phagocytotic amoebae, the myosin VI immunoanalog was visible throughout the cells, including pinocytotic channels and pinocytotic vesicles as well as phagosomes and emerging phagocytic cups. Blocking endogenous protein with anti-porcine myosin VI antibody (introduced into cells by means of microinjection) caused severe defects in pinocytosis and phagocytosis. In comparison with control cells, the treated amoebae formed ~75% less pinocytotic channels and phagocytosed ~65% less Tetrahymena cells. These data indicate that the myosin VI immunoanalog has an important role in pinocytosis and phagocytosis in Amoeba proteus (Pal.).

  7. Allograft tolerance induced by donor apoptotic lymphocytes requires phagocytosis in the recipient

    Science.gov (United States)

    Sun, E.; Gao, Y.; Chen, J.; Roberts, A. I.; Wang, X.; Chen, Z.; Shi, Y.

    2004-01-01

    Cell death through apoptosis plays a critical role in regulating cellular homeostasis. Whether the disposal of apoptotic cells through phagocytosis can actively induce immune tolerance in vivo, however, remains controversial. Here, we report in a rat model that without using immunosuppressants, transfusion of apoptotic splenocytes from the donor strain prior to transplant dramatically prolonged survival of heart allografts. Histological analysis verified that rejection signs were significantly ameliorated. Splenocytes from rats transfused with donor apoptotic cells showed a dramatically decreased response to donor lymphocyte stimulation. Most importantly, blockade of phagocytosis in vivo, either with gadolinium chloride to disrupt phagocyte function or with annexin V to block binding of exposed phosphotidylserine to its receptor on phagocytes, abolished the beneficial effect of transfused apoptotic cells on heart allograft survival. Our results demonstrate that donor apoptotic cells promote specific allograft acceptance and that phagocytosis of apoptotic cells in vivo plays a crucial role in maintaining immune tolerance.

  8. Antimicrobial (Drug) Resistance

    Science.gov (United States)

    ... the past 70 years, antimicrobial drugs, such as antibiotics, have been successfully used to treat patients with bacterial and infectious diseases. Why Is the Study of Antimicrobial (Drug) Resistance a Priority for NIAID? Over time, many infectious ...

  9. Animation of Antimicrobial Resistance

    Medline Plus

    Full Text Available ... Animal & Veterinary Cosmetics Tobacco Products Animal & ... antimicrobial resistance both emerges and proliferates among bacteria. Over time, the use of antimicrobial drugs will result in the development ...

  10. Mechanisms of xenogeneic baboon platelet aggregation and phagocytosis by porcine liver sinusoidal endothelial cells.

    Directory of Open Access Journals (Sweden)

    Qiang Peng

    Full Text Available BACKGROUND: Baboons receiving xenogeneic livers from wild type and transgenic pigs survive less than 10 days. One of the major issues is the early development of profound thrombocytopenia that results in fatal hemorrhage. Histological examination of xenotransplanted livers has shown baboon platelet activation, phagocytosis and sequestration within the sinusoids. In order to study the mechanisms of platelet consumption in liver xenotransplantation, we have developed an in vitro system to examine the interaction between pig endothelial cells with baboon platelets and to thereby identify molecular mechanisms and therapies. METHODS: Fresh pig hepatocytes, liver sinusoidal and aortic endothelial cells were isolated by collagenase digestion of livers and processing of aortae from GTKO and Gal+ MGH-miniature swine. These primary cell cultures were then tested for the differential ability to induce baboon or pig platelet aggregation. Phagocytosis was evaluated by direct observation of CFSE labeled-platelets, which are incubated with endothelial cells under confocal light microscopy. Aurintricarboxylic acid (GpIb antagonist blocking interactions with von Willebrand factor/vWF, eptifibatide (Gp IIb/IIIa antagonist, and anti-Mac-1 Ab (anti-α(Mβ(2 integrin Ab were tested for the ability to inhibit phagocytosis. RESULTS: None of the pig cells induced aggregation or phagocytosis of porcine platelets. However, pig hepatocytes, liver sinusoidal and aortic endothelial cells (GTKO and Gal+ all induced moderate aggregation of baboon platelets. Importantly, pig liver sinusoidal endothelial cells efficiently phagocytosed baboon platelets, while pig aortic endothelial cells and hepatocytes had minimal effects on platelet numbers. Anti-MAC-1 Ab, aurintricarboxylic acid or eptifibatide, significantly decreased baboon platelet phagocytosis by pig liver endothelial cells (P<0.01. CONCLUSIONS: Although pig hepatocytes and aortic endothelial cells directly caused

  11. A numerical analysis model for interpretation of flow cytometric studies of ex vivo phagocytosis.

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    Ted S Strom

    Full Text Available The study of ex vivo phagocytosis via flow cytometry requires that one distinguish experimentally between uptake and adsorption of fluorescently labeled targets by phagocytes. Removal of the latter quantity from the analysis is the most common means of analyzing such data. Because the probability of phagocytosis is a function of the probability of adsorption, and because partially quenched fluorescence after uptake often overlaps with that of negative controls, this approach is suboptimal at best. Here, we describe a numerical analysis model which overcomes these limitations. We posit that the random adsorption of targets to macrophages, and subsequent phagocytosis, is a function of three parameters: the ratio of targets to macrophages (m, the mean fluorescence intensity imparted to the phagocyte by the internalized target (alpha, and the probability of phagocytosis per adsorbed target (p. The potential values of these parameters define a parameter space and their values at any point in parameter space can be used to predict the fraction of adsorption(+ and [adsorption(-, phagocytosis(+] cells that might be observed experimentally. By systematically evaluating the points in parameter space for the latter two values and comparing them to experimental data, the model arrives at sets of parameter values that optimally predict such data. Using activated THP-1 cells as macrophages and platelets as targets, we validate the model by demonstrating that it can distinguish between the effects of experimental changes in m, alpha, and p. Finally, we use the model to demonstrate that platelets from a congenitally thrombocytopenic WAS patient show an increased probability of ex vivo phagocytosis. This finding correlates with other evidence that rapid in vivo platelet consumption contributes significantly to the thrombocytopenia of WAS. Our numerical analysis method represents a useful and innovative approach to multivariate analysis.

  12. Measuring Granulocyte and Monocyte Phagocytosis and Oxidative Burst Activity in Human Blood.

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    Meaney, Mary Pat; Nieman, David C; Henson, Dru A; Jiang, Qi; Wang, Fu-Zhang

    2016-09-12

    The granulocyte and monocyte phagocytosis and oxidative burst (OB) activity assay can be used to study the innate immune system. This manuscript provides the necessary methodology to add this assay to an exercise immunology arsenal. The first step in this assay is to prepare two aliquots ("H" and "F") of whole blood (heparin). Then, dihydroethidium is added to the H aliquot, and both aliquots are incubated in a warm water bath followed by a cold water bath. Next, Staphylococcus aureus (S. aureus) is added to the H aliquot and fluorescein isothiocyanate-labeled S. aureus is added to the F aliquot (bacteria:phagocyte = 8:1), and both aliquots are incubated in a warm water bath followed by a cold water bath. Then, trypan blue is added to each aliquot to quench extracellular fluorescence, and the cells are washed with phosphate-buffered saline. Next, the red blood cells are lysed, and the white blood cells are fixed. Finally, a flow cytometer and appropriate analysis software are used to measure granulocyte and monocyte phagocytosis and OB activity. This assay has been used for over 20 years. After heavy and prolonged exertion, athletes experience a significant but transient increase in phagocytosis and an extended decrease in OB activity. The post-exercise increase in phagocytosis is correlated with inflammation. In contrast to normal weight individuals, granulocyte and monocyte phagocytosis is chronically elevated in overweight and obese participants, and is modestly correlated with C-reactive protein. In summary, this flow cytometry-based assay measures the phagocytosis and OB activity of phagocytes and can be used as an additional measure of exercise- and obesity-induced inflammation.

  13. Endomorphins 1 and 2 modulate chemotaxis, phagocytosis and superoxide anion production by microglia.

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    Azuma, Y; Ohura, K; Wang, P L; Shinohara, M

    2001-09-03

    We evaluate the role of endomorphins 1 and 2 on microglial functions. Endomorphins 1 and 2 blocked phagocytosis of Escherichia coli. In addition, both markedly inhibited chemotaxis toward zymosan-activated serum. In contrast, when microglia was preincubated with these endomorphins, followed by incubation with LPS before stimulation with phorbol 12-myristate 13-acetate (PMA) at 200 nM, they potentiated superoxide anion production. Furthermore, when microglia was preincubated with these endomorphins together with PMA at 20 nM, followed by stimulation with PMA at 200 nM, superoxide anion production was potentiated. These results suggest that endomorphins 1 and 2 modulate phagocytosis, chemotaxis and superoxide anion production by microglia.

  14. Beta-adrenergic stimulation of phagocytosis in the unicellular eukaryote Paramecium aurelia.

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    Wyroba, E

    1989-08-01

    Bete-adrenergic agonists isoproterenol and norepinephrine enhanced phagocytosis in Paramecium. Stimulation was stereospecific, dose-dependent and inhibited by the beta-agonists propranolol and alprenolol. Phorbol ester and forskolin potentiated the stimulatory effect of catecholamines on Paramecium phagocytosis. The dansyl analogue of propranolol (DAPN) was used for fluorescent visualization of the beta-adrenergic receptor sites in Paramecium which have been found to be localized at the cell membrane and within the membrane of the nascent digestive vacuoles. The appearance of the characteristic fluorescent pattern has been blocked by 1-propranolol.

  15. Delayed phagocytosis and bacterial killing in Chediak-Higashi syndrome neutrophils detected by a fluorochrome assay: ultrastructural aspects

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    Raquel Bellinati-Pires

    1992-12-01

    Full Text Available The few studies already published about phagocyte functions in Chediak-Higashi syndrome (CHS has stated that neutrophils present slow rate of bacterial killing but normally ingest microorganisms. In the present study, both phagocytosis and killing of Staphylococcus aureus were verified to be in neutrophils from two patients with CHS when these functions were simultaneously evaluated by a fluorochrome phagocytosis assay. Electron microscopic examination showed morphologic differences among neutophils from CHS patients and normal neutrophils regarding the cytoplasmic structures and the aspects of the phagolysosomes. It was noteworthy the presence of giant phagolysosomes enclosing bacteria in active proliferation commonly observed in CHS neutrophils after 45 min of phagocytosis, wich corresponded with the impaired bactericidal activity of these leukocytes. The present results suggest that phagocytosis may also be defective in CHS, and point out to the sensitivity of the fluorochrome phagocytosis assay and its application in clinical laboratories.

  16. IgM-Dependent Phagocytosis in Microglia Is Mediated by Complement Receptor 3, Not Fcα/μ Receptor.

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    Weinstein, Jonathan R; Quan, Yi; Hanson, Josiah F; Colonna, Lucrezia; Iorga, Michael; Honda, Shin-ichiro; Shibuya, Kazuko; Shibuya, Akira; Elkon, Keith B; Möller, Thomas

    2015-12-01

    Microglia play an important role in receptor-mediated phagocytosis in the CNS. In brain abscess and other CNS infections, invading bacteria undergo opsonization with Igs or complement. Microglia recognize these opsonized pathogens by Fc or complement receptors triggering phagocytosis. In this study, we investigated the role of Fcα/μR, the less-studied receptor for IgM and IgA, in microglial phagocytosis. We showed that primary microglia, as well as N9 microglial cells, express Fcα/μR. We also showed that anti-Staphylococcus aureus IgM markedly increased the rate of microglial S. aureus phagocytosis. To unequivocally test the role of Fcα/μR in IgM-mediated phagocytosis, we performed experiments in microglia from Fcα/μR(-/-) mice. Surprisingly, we found that IgM-dependent phagocytosis of S. aureus was similar in microglia derived from wild-type or Fcα/μR(-/-) mice. We hypothesized that IgM-dependent activation of complement receptors might contribute to the IgM-mediated increase in phagocytosis. To test this, we used immunologic and genetic inactivation of complement receptor 3 components (CD11b and CD18) as well as C3. IgM-, but not IgG-mediated phagocytosis of S. aureus was reduced in wild-type microglia and macrophages following preincubation with an anti-CD11b blocking Ab. IgM-dependent phagocytosis of S. aureus was also reduced in microglia derived from CD18(-/-) and C3(-/-) mice. Taken together, our findings implicate complement receptor 3 and C3, but not Fcα/μR, in IgM-mediated phagocytosis of S. aureus by microglia.

  17. Dissimilar and similar functional properties of complement receptor-3 in microglia and macrophages in combating yeast pathogens by phagocytosis.

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    Hadas, Smadar; Reichert, Fanny; Rotshenker, Shlomo

    2010-05-01

    Central nervous system (CNS) microglia (MG) and peripheral tissue macrophages (MO) remove pathogens by phagocytosis. Zymosan, a model yeast pathogen, is a beta-glucan rich particle that readily activates the complement system and then becomes C3bi-opsonized (op). Complement receptor-3 (CR3) has initially been implicated in mediating the phagocytosis of both C3bi-op and non-opsonized (nop) zymosan by MO through C3bi and beta-glucan binding sites, respectively. Later, the role of CR3 as a phagocytic beta-glucan receptor has been questioned and the supremacy of beta-glucan receptor Dectin-1 advocated. We compare here between primary mouse CNS MG and peripheral tissue MO with respect to CR3 and Dectin-1 mediated phagocytosis of C3bi-op and nop zymosan. We report that MG and MO display similar as well as dissimilar functional properties in this respect. Although CR3 and Dectin-1 function both as beta-glucan/non-opsonic receptors in MG during nop zymosan phagocytosis, Dectin-1, but not CR3, does so in MO. CR3 functions also as a C3bi/opsonic receptor in MG and MO during C3bi-op zymosan phagocytosis, leading to phagocytosis which is more efficient than that of nop zymosan. Dectin-1 contributes, albeit less than CR3, to phagocytosis of C3bi-op zymosan in MG and further less in MO, suggesting that C3bi-opsonization does not block all beta-glucan sites on zymosan from binding Dectin-1 on phagocytes. Thus, altogether CR3 and Dectin-1 contribute both to phagocytosis of nop and C3bi-op zymosan in MG, whereas MO switch from CR3-independent/Dectin-1-dependent phagocytosis of nop zymosan to phagocytosis of C3bi-op zymosan where CR3 dominates over Dectin-1.

  18. Anti-antimicrobial Peptides

    Science.gov (United States)

    Ryan, Lloyd; Lamarre, Baptiste; Diu, Ting; Ravi, Jascindra; Judge, Peter J.; Temple, Adam; Carr, Matthew; Cerasoli, Eleonora; Su, Bo; Jenkinson, Howard F.; Martyna, Glenn; Crain, Jason; Watts, Anthony; Ryadnov, Maxim G.

    2013-01-01

    Antimicrobial or host defense peptides are innate immune regulators found in all multicellular organisms. Many of them fold into membrane-bound α-helices and function by causing cell wall disruption in microorganisms. Herein we probe the possibility and functional implications of antimicrobial antagonism mediated by complementary coiled-coil interactions between antimicrobial peptides and de novo designed antagonists: anti-antimicrobial peptides. Using sequences from native helical families such as cathelicidins, cecropins, and magainins we demonstrate that designed antagonists can co-fold with antimicrobial peptides into functionally inert helical oligomers. The properties and function of the resulting assemblies were studied in solution, membrane environments, and in bacterial culture by a combination of chiroptical and solid-state NMR spectroscopies, microscopy, bioassays, and molecular dynamics simulations. The findings offer a molecular rationale for anti-antimicrobial responses with potential implications for antimicrobial resistance. PMID:23737519

  19. [Antimicrobial prophylaxis in surgery].

    Science.gov (United States)

    Cisneros, José Miguel; Rodríguez-Baño, Jesús; Mensa, José; Trilla, Antoni; Cainzos, Miguel

    2002-01-01

    Antimicrobial prophylaxis in surgery refers to a very brief course of an antimicrobial agent initiated just before the start of the procedure. The efficacy of antimicrobials to prevent postoperative infection at the site of surgery (incisional superficial, incisional deep, or organ/space infection) has been demonstrated for many surgical procedures. Nevertheless, the majority of studies centering on the quality of preoperative prophylaxis have found that a high percentage of the antimicrobials used are inappropriate for this purpose. This work discusses the scientific basis for antimicrobial prophylaxis, provides general recommendations for its correct use and specific recommendations for various types of surgery. The guidelines for surgical antimicrobial prophylaxis are based on results from well-designed studies, whenever possible. These guidelines are focussed on reducing the incidence of infection at the surgical site while minimizing the contribution of preoperative administration of antimicrobials to the development of bacterial resistance.

  20. The effect of oxidative stress on phagocytosis and apoptosis in the earthworm Eisenia hortensis

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    SL Fuller-Espie

    2010-03-01

    Full Text Available The effect of exogenous hydrogen peroxide (H202 on phagocytic function and apoptosis in coelomocytes from Eisenia hortensis was investigated. Treating coelomocytes with H202 (0.26 to 8.4 mM evoked a significant increase in phagocytosis for one or more of the concentrations of H202 employed in 67 % of cases. Using annexin V-FITC we show that H202 induced apoptosis of coelomocytes in vitro. We found that 100 % of viable coelomocyte populations exhibited significant increases in phosphatidylserine translocation for one or more of the concentrations of H202 tested (8.4 to 67.6 mM. Using a fluorescent inhibitor of caspases, we revealed the presence of activated caspases observing increased caspase activity in 67 % of viable coelomocyte populations treated with 33.8mM H202, and in 100 % of cases treated with 67.6 mM H202. Agarose gel electrophoresis and the TUNEL assay showed DNA fragmentation in samples treated with 16.9 and 33.8 mM H202. In addition, endogenous H202 production during phagocytosis by hyaline amoebocytes was detected using a fluorogenic substrate. Thus, free radicals not only appear to facilitate phagocytosis and are produced during phagocytosis, but they also promote an oxidative-stress-induced apoptosis that may play an important function in regulating innate immune responses in E. hortensis

  1. Kaurane diterpenes protect against apoptosis and inhibition of phagocytosis in activated macrophages.

    Science.gov (United States)

    de las Heras, B; Hortelano, S; Girón, N; Bermejo, P; Rodríguez, B; Boscá, L

    2007-09-01

    The kaurane diterpenes foliol and linearol are inhibitors of the activation of nuclear factor kappaB, a transcription factor involved in the inflammatory response. Effects of these diterpenes on apoptosis and phagocytosis have been analysed in cultured peritoneal macrophages and in the mouse macrophage cell line, RAW 264.7. Macrophages were maintained in culture and activated with pro-inflammatory stimuli in the absence or presence of diterpenes. Apoptosis and the phagocytosis in these cells under these conditions were determined. Incubation of macrophages with a mixture of bacterial lipopolysaccharide (LPS)/interferon-gamma (IFN-gamma) induced apoptosis through a NO-dependent pathway, an effect significantly inhibited by foliol and linearol in the low muM range, without cytotoxic effects. Apoptosis in macrophages induced by NO donors was also inhibited. The diterpenes prevented apoptosis through a mechanism compatible with the inhibition of caspase-3 activation, release of cytochrome c to the cytosol and p53 overexpression, as well as an alteration in the levels of proteins of the Bcl-2 family, in particular, the levels of Bax. Cleavage of poly(ADP-ribose) polymerase, a well-established caspase substrate, was reduced by these diterpenes. Treatment of cells with foliol and linearol decreased phagocytosis of zymosan bioparticles by RAW 264.7 cells and to a greater extent by peritoneal macrophages. Both diterpenes protected macrophages from apoptosis and inhibited phagocytosis, resulting in a paradoxical control of macrophage function, as viability was prolonged but inflammatory and phagocytic functions were impaired.

  2. In vitro phagocytosis of collagens by immortalised human retinal Muller cells

    NARCIS (Netherlands)

    Ponsioen, Theodorus Leonardus; van Luyn, Marja Johanna Adriana; van der Worp, Roelofje Jacoba; Nolte, Ilja Maria; Hooymans, Johanna Martina Maria; Los, Leonoor Inge

    2007-01-01

    Purpose: This study is a first step to investigate phagocytosis of collagens by human retinal Muller cells, since Muller cells could be involved in remodelling of the vitreous and vitreoretinal interface in the human eye. Methods: Muller cells in culture were exposed to 2.0 mu m fluorescent latex be

  3. Mechanism involved in phagocytosis and killing of Listeria monocytogenes by Acanthamoeba polyphaga.

    Science.gov (United States)

    Akya, Alisha; Pointon, Andrew; Thomas, Connor

    2009-10-01

    Intra-cellular pathogen, Listeria monocytogenes, is capable of invasion and survival within mammalian cells. However, Acanthamoeba polyphaga trophozoites phagocytose and rapidly degrade Listeria cells. In order to provide more information on amoeba phagocytosis and killing mechanisms, this study used several inhibitor agents known to affect the phagocytosis and killing of bacteria by eukaryotes. Amoebae were pre-treated with mannose, cytochalasin D, wortmannin, suramin, ammonium chloride, bafilomycin A and monensin followed by co-culture with bacteria. Phagocytosis and killing of bacterial cells by amoeba trophozoites was assessed using plate counting methods and microscopy. The data presented indicates that actin polymerisation and cytoskeletal rearrangement are involved in phagocytosis of L. monocytogenes cells by A. polyphaga trophozoites. Further, both phagosomal acidification and phagosome-lysosome fusion are involved in killing and degradation of L. monocytogenes cells by A. polyphaga. However, the mannose-binding protein receptor does not play an important role in uptake of bacteria by amoeba trophozoites. In conclusion, this data reveals the similar principles of molecular mechanisms used by different types of eukaryotes in uptake and killing of bacteria.

  4. The Mannose Receptor Is Involved in the Phagocytosis of Mycobacteria-Induced Apoptotic Cells

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    Teresa Garcia-Aguilar

    2016-01-01

    Full Text Available Upon Mycobacterium tuberculosis infection, macrophages may undergo apoptosis, which has been considered an innate immune response. The pathways underlying the removal of dead cells in homeostatic apoptosis have been extensively studied, but little is known regarding how cells that undergo apoptotic death during mycobacterial infection are removed. This study shows that macrophages induced to undergo apoptosis with mycobacteria cell wall proteins are engulfed by J-774A.1 monocytic cells through the mannose receptor. This demonstration was achieved through assays in which phagocytosis was inhibited with a blocking anti-mannose receptor antibody and with mannose receptor competitor sugars. Moreover, elimination of the mannose receptor by a specific siRNA significantly diminished the expression of the mannose receptor and the phagocytosis of apoptotic cells. As shown by immunofluorescence, engulfed apoptotic bodies are initially located in Rab5-positive phagosomes, which mature to express the phagolysosome marker LAMP1. The phagocytosis of dead cells triggered an anti-inflammatory response with the production of TGF-β and IL-10 but not of the proinflammatory cytokines IL-12 and TNF-α. This study documents the previously unreported participation of the mannose receptor in the removal of apoptotic cells in the setting of tuberculosis (TB infection. The results challenge the idea that apoptotic cell phagocytosis in TB has an immunogenic effect.

  5. Influence of fluoroquinolones on phagocytosis and killing of Candida albicans by human polymorphonuclear neutrophils.

    Science.gov (United States)

    Gruger, Thomas; Morler, Caroline; Schnitzler, Norbert; Brandenburg, Kerstin; Nidermajer, Sabine; Horre, Regine; Zundorf, Josef

    2008-11-01

    Candida albicans infections often occur during or shortly after antibacterial treatment. Phagocytosis by polymorphonuclear neutrophil granulocytes (PMN) is the most important primarily defence mechanism against C. albicans. Certain antibiotics such as some fluoroquinolones (FQ) are known to influence phagocyte functions. Thus, we investigated the influence of older and newer FQ on the phagocytosis and killing of C. albicans by human PMN paying special attention to CD11b expression of these cells as an indicator of the degree of their activation. In order to obtain comprehensive and comparable results we tested 13 FQ over a wide range of concentrations and in a time dependent manner in a standardized approach. When used at therapeutic concentrations, the FQ tested did not influence to a clinically significant degree the phagocytosis or the killing of C. albicans by human PMN and also not their activation. However, at high concentrations those FQ with cyclopropyl-moiety at position N1 showed increase in CD11b expression and diminished phagocytosis and oxidative burst.

  6. Surfactant protein A regulates IgG-mediated phagocytosis in inflammatory neutrophils.

    Science.gov (United States)

    Wofford, Jessica A; Wright, Jo Rae

    2007-12-01

    Surfactant proteins (SP)-A and SP-D have been shown to affect the functions of a variety of innate immune cells and to interact with various immune proteins such as complement and immunoglobulins. The goal of the current study is to test the hypothesis that SP-A regulates IgG-mediated phagocytosis by neutrophils, which are major effector cells of the innate immune response that remove invading pathogens by phagocytosis and by extracellular killing mediated by reactive oxygen and nitrogen. We have previously shown that SP-A stimulates chemotaxis by inflammatory, but not peripheral, neutrophils. To evaluate the ability of SP-A to modulate IgG-mediated phagocytosis, polystyrene beads were coated with BSA and treated with anti-BSA IgG. SP-A significantly and specifically enhanced IgG-mediated phagocytosis by inflammatory neutrophils, but it had no effect on beads not treated with IgG. SP-A bound to IgG-coated beads and enhanced their uptake via direct interactions with the beads as well as direct interactions with the neutrophils. SP-A did not affect reactive oxygen production or binding of IgG to neutrophils and had modest effects on polymerization of actin. These data suggest that SP-A plays an important role in mediating the phagocytic response of neutrophils to IgG-opsonized particles.

  7. Concentration-dependent effect of fibrinogen on IgG-specific antigen binding and phagocytosis.

    Science.gov (United States)

    Boehm, Tobias Konrad; Sojar, Hakimuddin; Denardin, Ernesto

    2010-01-01

    In this paper, we aim to characterize fibrinogen-IgG interactions, and explore how fibrinogen alters IgG-mediated phagocytosis. Using enzyme-linked binding assays, we found that fibrinogen binding to IgG is optimized for surfaces coated with high levels of IgG. Using a similar method, we have shown that for an antigen unable to specifically bind fibrinogen, fibrinogen enhances binding of antibodies towards that antigen. For binding of IgG antibodies to cells expressing Fc receptors, we found a bimodal binding response, where low levels of fibrinogen enhance binding of antibody to Fc receptors and high levels reduce it. This corresponds to a bimodal effect on phagocytosis of IgG-coated particles, which is inhibited in the presence of excess IgG during coating of the particles with antibodies and fibrinogen. We conclude that fibrinogen can modulate phagocytosis of IgG-coated particles in vitro by changing IgG binding behavior, and that high fibrinogen levels could negatively affect phagocytosis.

  8. Rediae of echinostomatid and heterophyid trematodes suppress phagocytosis of haemocytes in Littorina littorea (Gastropoda: Prosobranchia).

    Science.gov (United States)

    Iakovleva, Nadya V; Shaposhnikova, Tania G; Gorbushin, Alexander M

    2006-05-01

    A modulation of the phagocytic activity of hemocytes from the common periwinkle Littorina littorea by secretory-excretory products (SEP) released by trematode rediae during axenic in vitro cultivation was studied. The SEP released by the parasites Himasthla elongata (Echinostomatidae) and Cryptocotyle lingua (Heterophyidae) were found to inhibit the phagocytosis of zymozan particles by periwinkle hemocytes. The specificity of SEP effects was assessed: SEP of Himasthla militaris and Cryptocotyle concavum, two trematodes belonging to the same genera but infecting another closely related prosobranch snail Hydrobia ulvae, were also shown to be able to suppress L. littorea hemocytes phagocytic activity. However, no decrease in phagocytosis rate was observed when SEP of H. elongata and C. lingua were applied to monolayers of hemocytes from the bivalve mollusc Mytilus edulis. SEP from H. elongata was fractionated; only those fractions containing proteins of molecular weight more than 50 kDa were shown to possess inhibitory activity. Different H. elongata SEP concentrations were tested in for their ability to suppress phagocytosis by L. littorea hemocytes. Even very low SEP concentrations were shown to retain their ability to decrease phagocytosis rate, the inhibitory effect being dose-dependent. Hemocytes derived from snails naturally infected with H. elongata were also found to have lower phagocytic ability as compared to healthy individuals.

  9. Comparative in vitro phagocytosis and F-actin polymerization of bovine neonatal neutrophils.

    Science.gov (United States)

    Moiola, F; Spycher, M; Wyder-Walther, M; Zwahlen, R D

    1994-04-01

    Analysis of neonatal neutrophil (PMN) functions should help to reveal factors which could contribute to the impaired host defense system of neonates. We analysed functional parameters of PMN from newborn calves (N-PMN) and adult bovines (A-PMN): cellular volume and F-actin content upon stimulation with complement factors, by cytofluorometry and phagocytosis of E. coli 78:80B with a colorimetric assay. Polymerization of F-actin was rapid in both N- and A-PMN, but reached higher levels in N-PMN. N-PMN are significantly smaller than A-PMN throughout the whole activation time. Percentage of phagocytosing PMN, the rate of phagocytosis, and the rate of killing are similar between A- and N-PMN after opsonization of bacteria with adult serum (AS). Opsonization with newborn serum (NS) reduced all three examined parameters: in A-PMN more (P dexamethasone) and non-steroidal (phenylbutazone) anti-inflammatory drugs inhibited phagocytosis by N-PMN less than by A-PMN. Higher relative F-actin content of N-PMN can be correlated with the documented functional hyperactivity of bovine N-PMN. However, the exaggerated impairment of phagocytosis in calves observed after age-matched opsonization of bacteria could potentially indicate a specific host defence defect.

  10. Diclofenac enhances proinflammatory cytokine-induced phagocytosis of cultured microglia via nitric oxide production

    Energy Technology Data Exchange (ETDEWEB)

    Kakita, Hiroki [Department of Molecular Neurobiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan); Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan); Aoyama, Mineyoshi, E-mail: ao.mine@med.nagoya-cu.ac.jp [Department of Molecular Neurobiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan); Nagaya, Yoshiaki; Asai, Hayato [Department of Molecular Neurobiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan); Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan); Hussein, Mohamed Hamed [Neonatal Intensive Care Unit, Pediatric Hospital, Cairo University, Cairo 11559 (Egypt); Maternal and Child Health Department, VACSERA, 51 Wizaret El-Zeraa-Agouza, Giza 22311 (Egypt); Suzuki, Mieko [Department of Molecular Neurobiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan); Kato, Shin [Department of Molecular Neurobiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan); Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan); Saitoh, Shinji [Department of Pediatrics and Neonatology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan); Asai, Kiyofumi [Department of Molecular Neurobiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601 (Japan)

    2013-04-15

    Influenza-associated encephalopathy (IAE) is a central nervous system complication with a high mortality rate, which is increased significantly by the non-steroidal anti-inflammatory drug diclofenac sodium (DCF). In the present study, we investigated the effects of DCF on brain immune cells (i.e. microglia) stimulated with three proinflammatory cytokines, namely tumor necrosis factor-α, interleukin-1β, and interferon-γ. Similar to previous findings in astrocytes, all three cytokines induced the expression of inducible NO synthase (iNOS), as well as NO production, in microglia. The addition of DCF to the culture system augmented iNOS expression and NO production. Immunocytochemical analysis and the phagocytosis assay revealed that cytokine treatment induced morphological changes to and phagocytosis by the microglia. The addition of DCF to the culture system enhanced microglial activation, as well as the phagocytic activity of cytokine-stimulated microglia. Inhibitors of nuclear factor (NF)-κB inhibited iNOS gene expression in cytokine-stimulated microglia with or without DCF, suggesting that the NF-κB pathway is one of the main signaling pathways involved. The iNOS inhibitor N{sup G}-monomethyl-L-arginine (L-NMMA) reduced both cytokine-induced phagocytosis and phagocytosis induced by the combination of cytokines plus DCF. Furthermore, the NO donor sodium nitroprusside induced phagocytosis, indicating that NO production is a key regulator of microglial phagocytosis. In conclusion, DCF acts synergistically with proinflammatory cytokines to increase the production of NO in microglia, leading to phagocytic activity of the activated microglia. These findings, together with previous observations regarding astrocytes, may explain the significant increase in mortality of IAE patients treated with DCF. - Highlights: ► Influenza-associated encephalopathy (IAE) is associated with a high mortality rate. ► Hyperimmunization in the brain is believed to be responsible for

  11. LRRK2 kinase inhibition prevents pathological microglial phagocytosis in response to HIV-1 Tat protein

    Directory of Open Access Journals (Sweden)

    Marker Daniel F

    2012-11-01

    Full Text Available Abstract Background Human Immunodeficiency Virus-1 (HIV-1 associated neurocognitive disorders (HANDs are accompanied by significant morbidity, which persists despite the use of combined antiretroviral therapy (cART. While activated microglia play a role in pathogenesis, changes in their immune effector functions, including phagocytosis and proinflammatory signaling pathways, are not well understood. We have identified leucine-rich repeat kinase 2 (LRRK2 as a novel regulator of microglial phagocytosis and activation in an in vitro model of HANDs, and hypothesize that LRRK2 kinase inhibition will attenuate microglial activation during HANDs. Methods We treated BV-2 immortalized mouse microglia cells with the HIV-1 trans activator of transcription (Tat protein in the absence or presence of LRRK2 kinase inhibitor (LRRK2i. We used Western blot, qRT-PCR, immunocytochemistry and latex bead engulfment assays to analyze LRRK2 protein levels, proinflammatory cytokine and phagocytosis receptor expression, LRRK2 cellular distribution and phagocytosis, respectively. Finally, we utilized ex vivo microfluidic chambers containing primary hippocampal neurons and BV-2 microglia cells to investigate microglial phagocytosis of neuronal axons. Results We found that Tat-treatment of BV-2 cells induced kinase activity associated phosphorylation of serine 935 on LRRK2 and caused the formation of cytoplasmic LRRK2 inclusions. LRRK2i decreased Tat-induced phosphorylation of serine 935 on LRRK2 and inhibited the formation of Tat-induced cytoplasmic LRRK2 inclusions. LRRK2i also decreased Tat-induced process extension in BV-2 cells. Furthermore, LRRK2i attenuated Tat-induced cytokine expression and latex bead engulfment. We examined relevant cellular targets in microfluidic chambers and found that Tat-treated BV-2 microglia cells cleared axonal arbor and engulfed neuronal elements, whereas saline treated controls did not. LRRK2i was found to protect axons in the presence

  12. Synthesis of quaternary ammonium coated surfaces : Physico-chemistry, bacterial killing and phagocytosis

    NARCIS (Netherlands)

    Roest, Steven

    2016-01-01

    The number one cause of failure of biomaterial implants and devices is the occurrence of biomaterial-associated infection. A universal method to create biomaterial implants and devices with intrinsic antimicrobial functionalities is difficult. Immobilizing antimicrobial coatings on existing biomater

  13. A role for connexin43 in macrophage phagocytosis and host survival after bacterial peritoneal infection.

    Science.gov (United States)

    Anand, Rahul J; Dai, Shipan; Gribar, Steven C; Richardson, Ward; Kohler, Jeff W; Hoffman, Rosemary A; Branca, Maria F; Li, Jun; Shi, Xiao-Hua; Sodhi, Chhinder P; Hackam, David J

    2008-12-15

    The pathways that lead to the internalization of pathogens via phagocytosis remain incompletely understood. We now demonstrate a previously unrecognized role for the gap junction protein connexin43 (Cx43) in the regulation of phagocytosis by macrophages and in the host response to bacterial infection of the peritoneal cavity. Primary and cultured macrophages were found to express Cx43, which localized to the phagosome upon the internalization of IgG-opsonized particles. The inhibition of Cx43 using small interfering RNA or by obtaining macrophages from Cx43 heterozygous or knockout mice resulted in significantly impaired phagocytosis, while transfection of Cx43 into Fc-receptor expressing HeLa cells, which do not express endogenous Cx43, conferred the ability of these cells to undergo phagocytosis. Infection of macrophages with adenoviruses expressing wild-type Cx43 restored phagocytic ability in macrophages from Cx43 heterozygous or deficient mice, while infection with viruses that expressed mutant Cx43 had no effect. In understanding the mechanisms involved, Cx43 was required for RhoA-dependent actin cup formation under adherent particles, and transfection with constitutively active RhoA restored a phagocytic phenotype after Cx43 inactivation. Remarkably, mortality was significantly increased in a mouse model of bacterial peritonitis after Cx43 inhibition and in Cx43 heterozygous mice compared with untreated and wild-type counterparts. These findings reveal a novel role for Cx43 in the regulation of phagocytosis and rearrangement of the F-actin cytoskeleton, and they implicate Cx43 in the regulation of the host response to microbial infection.

  14. Gingipain-dependent augmentation by Porphyromonas gingivalis of phagocytosis of Tannerella forsythia.

    Science.gov (United States)

    Jung, Y-J; Jun, H-K; Choi, B-K

    2016-12-01

    In the pathogenesis of periodontitis, Porphyromonas gingivalis plays a role as a keystone pathogen that manipulates host immune responses leading to dysbiotic oral microbial communities. Arg-gingipains (RgpA and RgpB) and Lys-gingipain (Kgp) are responsible for the majority of bacterial proteolytic activity and play essential roles in bacterial virulence. Therefore, gingipains are often considered as therapeutic targets. This study investigated the role of gingipains in the modulation by P. gingivalis of phagocytosis of Tannerella forsythia by macrophages. Phagocytosis of T. forsythia was significantly enhanced by coinfection with P. gingivalis in a multiplicity of infection-dependent and gingipain-dependent manner. Mutation of either Kgp or Rgp in the coinfecting P. gingivalis resulted in attenuated enhancement of T. forsythia phagocytosis. Inhibition of coaggregation between the two bacterial species reduced phagocytosis of T. forsythia in mixed infection, and this coaggregation was dependent on gingipains. Inhibition of gingipain protease activities in coinfecting P. gingivalis abated the coaggregation and the enhancement of T. forsythia phagocytosis. However, the direct effect of protease activities of gingipains on T. forsythia seemed to be minimal. Although most of the phagocytosed T. forsythia were cleared in infected macrophages, more T. forsythia remained in cells coinfected with gingipain-expressing P. gingivalis than in cells coinfected with the gingipain-null mutant or infected only with T. forsythia at 24 and 48 h post-infection. Collectively, these results suggest that P. gingivalis, mainly via its gingipains, alters the clearance of T. forsythia, and provide some insights into the role of P. gingivalis as a keystone pathogen.

  15. Rho is required for the initiation of calcium signaling and phagocytosis by Fcgamma receptors in macrophages.

    Science.gov (United States)

    Hackam, D J; Rotstein, O D; Schreiber, A; Zhang, W j; Grinstein, S

    1997-09-15

    Phagocytosis of bacteria by macrophages and neutrophils is an essential component of host defense against infection. The mechanism whereby the interaction of opsonized particles with Fcgamma receptors triggers the engulfment of opsonized particles remains incompletely understood, although activation of tyrosine kinases has been recognized as an early step. Recent studies in other systems have demonstrated that tyrosine kinases can in turn signal the activation of small GTPases of the ras superfamily. We therefore investigated the possible role of Rho in Fc receptor-mediated phagocytosis. To this end we microinjected J774 macrophages with C3 exotoxin from Clostridium botulinum, which ADP-ribosylates and inactivates Rho. C3 exotoxin induced the retraction of filopodia, the disappearance of focal complexes, and a global decrease in the F-actin content of J774 cells. In addition, these cells exhibited increased spreading and the formation of vacuolar structures. Importantly, inactivation of Rho resulted in the complete abrogation of phagocytosis. Inhibition of Fcgamma receptor-mediated phagocytosis by C3 exotoxin was confirmed in COS cells, which become phagocytic upon transfection of the FcgammaRIIA receptor. Rho was found to be essential for the accumulation of phosphotyrosine and of F-actin around phagocytic cups and for Fcgamma receptor-mediated Ca2+ signaling. The clustering of receptors in response to opsonin, an essential step in Fcgamma-induced signaling, was the earliest event shown to be inhibited by C3 exotoxin. The effect of the toxin was specific, since clustering and internalization of transferrin receptors were unaffected by microinjection of C3. These data identify a role for small GTPases in Fcgamma receptor-mediated phagocytosis by leukocytes.

  16. Antimicrobial Stewardship from Policy to Practice: Experiences from UK Antimicrobial Pharmacists.

    Science.gov (United States)

    Gilchrist, Mark; Wade, Paul; Ashiru-Oredope, Diane; Howard, Philip; Sneddon, Jacqueline; Whitney, Laura; Wickens, Hayley

    2015-09-01

    Antimicrobial stewardship in the UK has evolved dramatically in the last 15 years. Factors driving this include initial central funding for specialist pharmacists and mandatory reductions in healthcare-associated infections (particularly Clostridium difficile infection). More recently, the introduction of national stewardship guidelines, and an increased focus on stewardship as part of the UK five-year antimicrobial resistance strategy, have accelerated and embedded developments. Antimicrobial pharmacists have been instrumental in effecting changes at an organizational and national level. This article describes the evolution of the antimicrobial pharmacist role, its impact, the progress toward the actions listed in the five-year resistance strategy, and novel emerging areas in stewardship in the UK.

  17. Endoplasmic reticulum‐resident Rab8A GTPase is involved in phagocytosis in the protozoan parasite Entamoeba histolytica

    Science.gov (United States)

    Hanadate, Yuki; Saito‐Nakano, Yumiko; Nakada‐Tsukui, Kumiko

    2016-01-01

    Summary Phagocytosis is indispensable for the pathogenesis of the intestinal protozoan parasite Entamoeba histolytica. Here, we showed that in E. histolytica Rab8A, which is generally involved in trafficking from the trans‐Golgi network to the plasma membrane in other organisms but was previously identified in phagosomes of the amoeba in the proteomic analysis, primarily resides in the endoplasmic reticulum (ER) and participates in phagocytosis. We demonstrated that down‐regulation of EhRab8A by small antisense RNA‐mediated transcriptional gene silencing remarkably reduced adherence and phagocytosis of erythrocytes, bacteria and carboxylated latex beads. Surface biotinylation followed by SDS‐PAGE analysis revealed that the surface expression of several proteins presumably involved in target recognition was reduced in the EhRab8A gene‐silenced strain. Further, overexpression of wild‐type EhRab8A augmented phagocytosis, whereas expression of the dominant‐negative form of EhRab8A resulted in reduced phagocytosis. These results indicated that EhRab8A regulates transport of surface receptor(s) for the prey from the ER to the plasma membrane. To our knowledge, this is the first report that the ER‐resident Rab GTPase is involved in phagocytosis through the regulation of trafficking of a surface receptor, supporting a premise of direct involvement of the ER in phagocytosis. PMID:26807810

  18. Antimicrobial proteins and polypeptides in pulmonary innate defence

    Directory of Open Access Journals (Sweden)

    Taggart Clifford C

    2006-02-01

    Full Text Available Abstract Inspired air contains a myriad of potential pathogens, pollutants and inflammatory stimuli. In the normal lung, these pathogens are rarely problematic. This is because the epithelial lining fluid in the lung is rich in many innate immunity proteins and peptides that provide a powerful anti-microbial screen. These defensive proteins have anti-bacterial, anti- viral and in some cases, even anti-fungal properties. Their antimicrobial effects are as diverse as inhibition of biofilm formation and prevention of viral replication. The innate immunity proteins and peptides also play key immunomodulatory roles. They are involved in many key processes such as opsonisation facilitating phagocytosis of bacteria and viruses by macrophages and monocytes. They act as important mediators in inflammatory pathways and are capable of binding bacterial endotoxins and CPG motifs. They can also influence expression of adhesion molecules as well as acting as powerful anti-oxidants and anti-proteases. Exciting new antimicrobial and immunomodulatory functions are being elucidated for existing proteins that were previously thought to be of lesser importance. The potential therapeutic applications of these proteins and peptides in combating infection and preventing inflammation are the subject of ongoing research that holds much promise for the future.

  19. The pineal gland does not control rod outer segment shedding and phagocytosis in the rat retina and pigment epithelium.

    Science.gov (United States)

    Tamai, M; Teirstein, P; Goldman, A; O'Brien, P; Chader, G

    1978-06-01

    Diurnal patterns of retinal outer segment shedding and phagocytosis by the pigment epithelium were examined in pinealectomized, superior-cervical-ganglionectomized, and sham-operated rats. Phagocytosis was quantitatively similar in all groups. Sharp increases in the number of large phagosomes were observed soon after lights were turned on in the tree sets of animals. Pinealectomized animals kept in constant darkness over a 24 hr period also exhibited normal shedding patterns. Our results suggest that the pineal does not exert a major influence on the daily rhythms of shedding and phagocytosis observed in the retina-pigment epithelium unit.

  20. With Friends Like These: The Complex Role of Neutrophils in the Progression of Severe Pneumonia

    Directory of Open Access Journals (Sweden)

    Roger D. Pechous

    2017-05-01

    Full Text Available Pneumonia is a leading cause of death from infection in the United States and across the globe. During pulmonary infection, clear resolution of host inflammatory responses occurs in the absence of appreciable lung damage. Neutrophils are the first wave of leukocytes to arrive in the lung upon infection. After activation, neutrophils traffic from the vasculature via transendothelial migration through the lung interstitium and into the alveolar space. Successful pulmonary immunity requires neutrophil-mediated killing of invading pathogens by phagocytosis and release of a myriad of antimicrobial molecules, followed by resolution of inflammation, neutrophil apoptosis, and clearing of dead or dying neutrophils by macrophages. In addition to their antimicrobial role, it is becoming clear that neutrophils are also important modulators of innate and adaptive immune responses, primarily through the release of cytokines and recruitment of additional waves of neutrophils into the airways. Though typically essential to combating severe pneumonia, neutrophil influx into the airways is a double-edged sword: Overzealous neutrophil activation can cause severe tissue damage as a result of the release of toxic agents including proteases, cationic polypeptides, cytokines, and reactive oxygen species (ROS aimed at killing invading microbes. In extreme cases, the damage caused by neutrophils and other innate immune mediators become the primary source of morbidity and mortality. Here, we review the complex role of neutrophils during severe pneumonia by highlighting specific molecules and processes that contribute to pulmonary immunity, but can also drive progression of severe disease. Depending on the identity of the infectious agent, enhancing or suppressing neutrophil-mediated responses may be key to effectively treating severe and typically lethal pneumonia.

  1. Antimicrobials in beekeeping.

    Science.gov (United States)

    Reybroeck, Wim; Daeseleire, Els; De Brabander, Hubert F; Herman, Lieve

    2012-07-06

    The bee diseases American and European foulbrood and nosemosis can be treated with anti-infectious agents. However, in the EU and the USA the use of these agents in beekeeping is strictly regulated due to the lack of tolerance (e.g. Maximum Residue Limit) for residues of antibiotics and chemotherapeutics in honey. This article reviews the literature dealing with antimicrobials of interest in apiculture, stability of these antimicrobials in honey, and disposition of the antimicrobials in honeybee hives.

  2. Animation of Antimicrobial Resistance

    Medline Plus

    Full Text Available ... more understandable to non-scientists by showing how bacterial antimicrobial resistance can develop and spread. All FDA CVM ... Education Inspections & Compliance Federal, State & Local ...

  3. Animation of Antimicrobial Resistance

    Medline Plus

    Full Text Available ... Resistance National Antimicrobial Resistance Monitoring System 2014 NARMS ... Note: If you need help accessing information in different file formats, see Instructions for Downloading ...

  4. Shifts in the fluorescence lifetime of EGFP during bacterial phagocytosis measured by phase-sensitive flow cytometry

    Science.gov (United States)

    Li, Wenyan; Houston, Kevin D.; Houston, Jessica P.

    2017-01-01

    Phase-sensitive flow cytometry (PSFC) is a technique in which fluorescence excited state decay times are measured as fluorescently labeled cells rapidly transit a finely focused, frequency-modulated laser beam. With PSFC the fluorescence lifetime is taken as a cytometric parameter to differentiate intracellular events that are challenging to distinguish with standard flow cytometry. For example PSFC can report changes in protein conformation, expression, interactions, and movement, as well as differences in intracellular microenvironments. This contribution focuses on the latter case by taking PSFC measurements of macrophage cells when inoculated with enhanced green fluorescent protein (EGFP)-expressing E. coli. During progressive internalization of EGFP-E. coli, fluorescence lifetimes were acquired and compared to control groups. It was hypothesized that fluorescence lifetimes would correlate well with phagocytosis because phagosomes become acidified and the average fluorescence lifetime of EGFP is known to be affected by pH. We confirmed that average EGFP lifetimes consistently decreased (3 to 2 ns) with inoculation time. The broad significance of this work is the demonstration of how high-throughput fluorescence lifetime measurements correlate well to changes that are not easily tracked by intensity-only cytometry, which is affected by heterogeneous protein expression, cell-to-cell differences in phagosome formation, and number of bacterium engulfed.

  5. Differential effects of gram-positive and gram-negative bacterial products on morphine induced inhibition of phagocytosis.

    Science.gov (United States)

    Ninkovic, Jana; Jana, Ninkovic; Anand, Vidhu; Vidhu, Anand; Dutta, Raini; Raini, Dutta; Zhang, Li; Saluja, Anuj; Meng, Jingjing; Koodie, Lisa; Lisa, Koodie; Banerjee, Santanu; Santanu, Banerjee; Roy, Sabita; Sabita, Roy

    2016-02-19

    Opioid drug abusers have a greater susceptibility to gram positive (Gram (+)) bacterial infections. However, the mechanism underlying opioid modulation of Gram (+) versus Gram (-) bacterial clearance has not been investigated. In this study, we show that opioid treatment resulted in reduced phagocytosis of Gram (+), when compared to Gram (-) bacteria. We further established that LPS priming of chronic morphine treated macrophages leads to potentiated phagocytosis and killing of both Gram (+) and Gram (-) bacteria in a P-38 MAP kinase dependent signaling pathway. In contrast, LTA priming lead to inhibition of both phagocytosis and bacterial killing. This study demonstrates for the first time the differential effects of TLR4 and TLR2 agonists on morphine induced inhibition of phagocytosis. Our results suggest that the incidence and severity of secondary infections with Gram (+) bacteria would be higher in opioid abusers.

  6. Synthesis and evaluation of chalcone derivatives as inhibitors of neutrophils' chemotaxis, phagocytosis and production of reactive oxygen species.

    Science.gov (United States)

    Bukhari, Syed N A; Tajuddin, Yasmin; Benedict, Vannessa J; Lam, Kok W; Jantan, Ibrahim; Jalil, Juriyati; Jasamai, Malina

    2014-02-01

    Inhibitory effects on neutrophils' chemotaxis, phagocytosis and production of reactive oxygen species (ROS) are among the important targets in developing anti-inflammatory agents and immunosuppressants. Eight series of chalcone derivatives including five newly synthesized series were assessed for their inhibitory effects on chemotaxis, phagocytosis and ROS production in human polymorphonuclear neutrophils (PMNs). Inhibition of PMNs' chemotaxis and phagocytosis abilities were investigated using the Boyden chamber technique and the Phagotest kit, respectively, while ROS production was evaluated using luminol- and lucigenin-based chemiluminescence assay. The new derivatives (4d and 8d), which contain 4-methylaminoethanol functional group were active in all the assays performed. It was also observed that some of the compounds were active in inhibiting chemotaxis while others suppressed phagocytosis and ROS production. The information obtained gave new insight into chalcone derivatives with the potential to be developed as immunomodulators.

  7. Phagocytosis and Killing of Carbapenem-Resistant ST258 Klebsiella pneumoniae by Human Neutrophils.

    Science.gov (United States)

    Kobayashi, Scott D; Porter, Adeline R; Dorward, David W; Brinkworth, Amanda J; Chen, Liang; Kreiswirth, Barry N; DeLeo, Frank R

    2016-05-15

    Carbapenem-resistant Klebsiella pneumoniae strains classified as multilocus sequence type 258 (ST258) are among the most widespread multidrug-resistant hospital-acquired pathogens. Treatment of infections caused by these organisms is difficult, and mortality is high. The basis for the success of ST258, outside of antibiotic resistance, remains incompletely determined. Here we tested the hypothesis that ST258K. pneumoniae has enhanced capacity to circumvent killing by human neutrophils, the primary cellular defense against bacterial infections. There was limited binding and uptake of ST258 by human neutrophils, and correspondingly, there was limited killing of bacteria. On the other hand, transmission electron microscopy revealed that any ingested organisms were degraded readily within neutrophil phagosomes, thus indicating that survival in the neutrophil assays is due to limited phagocytosis, rather than to microbicide resistance after uptake. Our findings suggest that enhancing neutrophil phagocytosis is a potential therapeutic approach for treatment of infection caused by carbapenem-resistant ST258K. pneumoniae.

  8. Phagocytosis of neutrophils in rabbits infected with antigenic variants of RHD (rabbit haemorrhagic disease) virus.

    Science.gov (United States)

    Niedźwiedzka-Rystwej, P; Deptuła, W

    2012-01-01

    The present study was aimed at determining changes in chosen elements of phagocytosis in rabbits infected with 3 antigenic variants of RHD - Hartmannsdorf, Pv97 and 9905, which differed in haemagglutination ability. The animals were tested for phagocytosis parameters, and the results revealed that the examined strains showed the differences. These variations regarded mainly Pv97 strain, as the intensity of the changes were 5 times stronger in comparison to strain Hartmannsdorf and 9905. As all of the strains examined are signified as antigenic variants, we have stated that this feature does not determine their immunological picture. The results suggest the existence of immunological dissimilarities among strains of the RHD virus, which was revealed for the first time in antigenic variants.

  9. Ability of Staphylococcus aureus coagulase genotypes to resist neutrophil bactericidal activity and phagocytosis

    DEFF Research Database (Denmark)

    Aarestrup, Frank Møller; Scott, N. L.; Sordillo, L. M.

    1994-01-01

    genotype. The interaction between bacteria and neutrophils was measured by phagocytosis and bactericidal effect. The average percent killing of bacteria was lowest (40.0%) with strains belonging to the most common genotype, medium (50%) with strains belonging to the intermediate type, and highest (64......; rare type, 10.5/cell). These findings suggest that one of the reasons for the variation in prevalence of different genotypes of S. aureus in the mammary gland is due to the superior ability of some types to resist phagocytosis and/or killing by bovine neutrophils......This study investigated the functional capabilities of neutrophils against different Staphylococcus aureus genotypes isolated from cows with mastitis. Six strains of S. aureus were chosen for use in the study, two with a common genotype, two with an intermediate genotype, and two with a rare...

  10. Effect of Baliospermum montanum root extract on phagocytosis by human neutrophils

    Directory of Open Access Journals (Sweden)

    Patil Kalpana

    2009-01-01

    Full Text Available Aqueous extract of roots of Baliospermum montanum was evaluated on preliminary basis for immunomodulatory activity by studying neutrophil phagocytic function. The different concentration of (25, 50, 100 mg/ml of aqueous extract of roots of Baliospermum montanum was subjected to study its effect on different in vitro methods of phagocytosis such as neutrophil locomotion, chemotaxis, immunostimulant activity of phagocytosis of killed Candida albicans and qualitative nitroblue tetrazolium test by using human neutrophils. This preliminary study revealed that Baliospermum montanum extract has stimulated chemotactic, phagocytic and intracellular killing potency of human neutrophils at the different concentration. From the results obtained it can be observed that the aqueous extract of Baliospermum montanum stimulate cell-mediated immune system by increasing neutrophil function.

  11. Animation of Antimicrobial Resistance

    Medline Plus

    Full Text Available ... use of antimicrobial drugs will result in the development of resistant strains of bacteria, complicating clinician's efforts to select the appropriate antimicrobial for treatment. Accordingly, efforts are underway in both veterinary and human medicine to preserve the effectiveness of these drugs. ...

  12. Animation of Antimicrobial Resistance

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    Full Text Available ... Skip to common links HHS U.S. Department of Health and Human Services U.S. Food and Drug Administration ... Tobacco Products Animal & Veterinary Home Animal & Veterinary Safety & Health Antimicrobial Resistance Animation of Antimicrobial Resistance Share Tweet ...

  13. Animation of Antimicrobial Resistance

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    Full Text Available ... CVM produced material may be copied, reproduced, and distributed as long as FDA's Center for Veterinary Medicine ... More in Antimicrobial Resistance National Antimicrobial Resistance Monitoring ... Note: If you need help accessing information in different file formats, see Instructions for Downloading ...

  14. Antimicrobial Peptides in 2014

    Directory of Open Access Journals (Sweden)

    Guangshun Wang

    2015-03-01

    Full Text Available This article highlights new members, novel mechanisms of action, new functions, and interesting applications of antimicrobial peptides reported in 2014. As of December 2014, over 100 new peptides were registered into the Antimicrobial Peptide Database, increasing the total number of entries to 2493. Unique antimicrobial peptides have been identified from marine bacteria, fungi, and plants. Environmental conditions clearly influence peptide activity or function. Human α-defensin HD-6 is only antimicrobial under reduced conditions. The pH-dependent oligomerization of human cathelicidin LL-37 is linked to double-stranded RNA delivery to endosomes, where the acidic pH triggers the dissociation of the peptide aggregate to release its cargo. Proline-rich peptides, previously known to bind to heat shock proteins, are shown to inhibit protein synthesis. A model antimicrobial peptide is demonstrated to have multiple hits on bacteria, including surface protein delocalization. While cell surface modification to decrease cationic peptide binding is a recognized resistance mechanism for pathogenic bacteria, it is also used as a survival strategy for commensal bacteria. The year 2014 also witnessed continued efforts in exploiting potential applications of antimicrobial peptides. We highlight 3D structure-based design of peptide antimicrobials and vaccines, surface coating, delivery systems, and microbial detection devices involving antimicrobial peptides. The 2014 results also support that combination therapy is preferred over monotherapy in treating biofilms.

  15. ANTIMICROBIAL HERBAL DRUGS

    Directory of Open Access Journals (Sweden)

    K. Nishteswar

    2011-12-01

    Full Text Available An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes (microbiocidal or prevent the growth of microbes (microbiostatic. Sulphonamide drugs were the first antimicrobial drugs, and paved the way for the antibiotic revolution in medicine. The first sulfonamide, trade named Prontosil, was actually a prodrug. However, with the development of antimicrobials, microorganisms have adapted and become resistant to previous antimicrobial agents. In view of certain side effects caused due to usage of modern antimicrobial drugs and antibiotics scientists have made some attempts to screen some of the Ayurvedic herbs, which possess broader spectrum of safety. Some selected herbs which are used by tribal and rural people for curing various infective diseases caused due to bacteria, virus and fungi have been reported to possess anti-microbial properties. In the present paper and attempt is made to review about the indigenous medicinal plant which exhibited antimicrobial properties.

  16. Delayed phagocytosis and bacterial killing in Chediak-Higashi syndrome neutrophils detected by a fluorochrome assay: ultrastructural aspects

    OpenAIRE

    Raquel Bellinati-Pires; Maristela M Salgado; Joazeiro, Paulo P.; Carneiro-Sampaio, Magda M. S.

    1992-01-01

    The few studies already published about phagocyte functions in Chediak-Higashi syndrome (CHS) has stated that neutrophils present slow rate of bacterial killing but normally ingest microorganisms. In the present study, both phagocytosis and killing of Staphylococcus aureus were verified to be in neutrophils from two patients with CHS when these functions were simultaneously evaluated by a fluorochrome phagocytosis assay. Electron microscopic examination showed morphologic differences among ne...

  17. Alternative Antimicrobial Approach: Nano-Antimicrobial Materials

    Directory of Open Access Journals (Sweden)

    Nurit Beyth

    2015-01-01

    Full Text Available Despite numerous existing potent antibiotics and other antimicrobial means, bacterial infections are still a major cause of morbidity and mortality. Moreover, the need to develop additional bactericidal means has significantly increased due to the growing concern regarding multidrug-resistant bacterial strains and biofilm associated infections. Consequently, attention has been especially devoted to new and emerging nanoparticle-based materials in the field of antimicrobial chemotherapy. The present review discusses the activities of nanoparticles as an antimicrobial means, their mode of action, nanoparticle effect on drug-resistant bacteria, and the risks attendant on their use as antibacterial agents. Factors contributing to nanoparticle performance in the clinical setting, their unique properties, and mechanism of action as antibacterial agents are discussed in detail.

  18. Impact of Hyperbaric Oxygenation on the Phagocytosis-Stimulating Function of the Operated Liver

    OpenAIRE

    Savilov, P. N.

    2008-01-01

    Objective: to study the ability of hyperbaric oxygenation (HBO) to eliminate impaired phagocytosis-stimulating hepatic function caused by hepatectomy (HE). Material and methods. Experiments were conducted on 82 outbred female albino rats exposed to HE (15—20% of the organ mass) and HBO at 3 ata for 50 min once daily three times within the first three days after surgery. The capacities of neutrophils and monocytes of arterial (aorta) and venous (portal vein, hepatic veins) blood to ingest and ...

  19. Phagocytosis of neuronal debris by microglia is associated with neuronal damage in multiple sclerosis.

    Science.gov (United States)

    Huizinga, Ruth; van der Star, Baukje J; Kipp, Markus; Jong, Rosa; Gerritsen, Wouter; Clarner, Tim; Puentes, Fabiola; Dijkstra, Christine D; van der Valk, Paul; Amor, Sandra

    2012-03-01

    Neuroaxonal degeneration is a pathological hallmark of multiple sclerosis (MS) contributing to irreversible neurological disability. Pathological mechanisms leading to axonal damage include autoimmunity to neuronal antigens. In actively demyelinating lesions, myelin is phagocytosed by microglia and blood-borne macrophages, whereas the fate of degenerating or damaged axons is unclear. Phagocytosis is essential for clearing neuronal debris to allow repair and regeneration. However, phagocytosis may lead to antigen presentation and autoimmunity, as has been described for neuroaxonal antigens. Despite this notion, it is unknown whether phagocytosis of neuronal antigens occurs in MS. Here, we show using novel, well-characterized antibodies to axonal antigens, that axonal damage is associated with HLA-DR expressing microglia/macrophages engulfing axonal bulbs, indicative of axonal damage. Neuronal proteins were frequently observed inside HLA-DR(+) cells in areas of axonal damage. In vitro, phagocytosis of neurofilament light (NF-L), present in white and gray matter, was observed in human microglia. The number of NF-L or myelin basic protein (MBP) positive cells was quantified using the mouse macrophage cell line J774.2. Intracellular colocalization of NF-L with the lysosomal membrane protein LAMP1 was observed using confocal microscopy confirming that NF-L is taken up and degraded by the cell. In vivo, NF-L and MBP was observed in cerebrospinal fluid cells from patients with MS, suggesting neuronal debris is drained by this route after axonal damage. In summary, neuroaxonal debris is engulfed, phagocytosed, and degraded by HLA-DR(+) cells. Although uptake is essential for clearing neuronal debris, phagocytic cells could also play a role in augmenting autoimmunity to neuronal antigens.

  20. A Sequential Model of Host Cell Killing and Phagocytosis by Entamoeba histolytica

    Directory of Open Access Journals (Sweden)

    Adam Sateriale

    2011-01-01

    Full Text Available The protozoan parasite Entamoeba histolytica is responsible for invasive intestinal and extraintestinal amebiasis. The virulence of Entamoeba histolytica is strongly correlated with the parasite's capacity to effectively kill and phagocytose host cells. The process by which host cells are killed and phagocytosed follows a sequential model of adherence, cell killing, initiation of phagocytosis, and engulfment. This paper presents recent advances in the cytolytic and phagocytic processes of Entamoeba histolytica in context of the sequential model.

  1. MFG-E8 mediates primary phagocytosis of viable neurons during neuroinflammation

    OpenAIRE

    Fricker, Michael; Neher, Jonas J.; Zhao, Jing-Wei; Théry, Clotilde; Tolkovsky, Aviva M; Brown, Guy C.

    2012-01-01

    Milk-fat globule EGF factor-8 (MFG-E8, SED1, lactadherin) is known to mediate the phagocytic removal of apoptotic cells by bridging phosphatidylserine (PS)-exposing cells and the vitronectin receptor (VR) on phagocytes. However, we show here that MFG-E8 can mediate phagocytosis of viable neurons during neuroinflammation induced by lipopolysaccharide (LPS), thereby causing neuronal death. In vitro, inflammatory neuronal loss is independent of apoptotic pathways, and is inhibited by blocking th...

  2. A TRP Channel in the Lysosome Regulates Large Particle Phagocytosis via Focal Exocytosis

    OpenAIRE

    2013-01-01

    Phagocytosis of large extracellular particles such as apoptotic bodies requires delivery of the intracellular endosomal and lysosomal membranes to form plasmalemmal pseudopods. Here we identified Mucolipin TRP channel 1 (TRPML1) as the key lysosomal Ca2+ channel regulating focal exocytosis and phagosome biogenesis. Both particle ingestion and lysosomal exocytosis are inhibited by synthetic TRPML1 blockers, and are defective in macrophages isolated from TRPML1 knockout mice. Furthermore, TRPML...

  3. Quantification of microglial phagocytosis by a flow cytometer-based assay.

    Science.gov (United States)

    Pul, Refik; Chittappen, Kandiyil Prajeeth; Stangel, Martin

    2013-01-01

    Microglia represent the largest population of phagocytes in the CNS and have a principal role in immune defense and inflammatory responses in the CNS. Their phagocytic activity can be studied by a variety of techniques, including a flow cytometry-based approach utilizing polystyrene latex beads. The flow cytometry-based microglial phagocytosis assay, which is presented here, offers the advantage of rapid and reliable analysis of thousands of cells in a quantitative fashion.

  4. R-MC46 monoclonal antibody stimulates adhesion and phagocytosis by rat macrophages

    Directory of Open Access Journals (Sweden)

    Gašić Sonja

    2004-01-01

    Full Text Available Background. In our previous experiments it was shown that R-MC46 monoclonal antibody (mAb, produced at our Institute, stimulated homotypic aggregation of rat granulocytes and production of proinflammatory cytokines. The aim of this study was to examine antigen expression and function, recognized by R-MC46 mAb on macrophages. Methods. The expression of R-MC46 antigen on thymic and peritoneal macrophages was investigated using immunocytochemistry and flow cytometry methods. Its biochemical characterization was performed by Western blot. The ability of R-MC46 mAb to modulate adhesion and phagocytosis by macrophages was studied by using co-culture experiments with autologous thymocytes. Results. R-MC46 mAb stained thymic macrophages more strongly than peritoneal macrophages. After in vivo treatment of peritoneal macrophages with Pristane, a significant up-regulation of the R-MC46 antigen expression was observed. Western blot analysis showed that the mAb recognized a low molecular weight antigen of about 5.5 kDa. R-MC46 mAb significantly enhanced binding and phagocytosis of thymocytes by both thymic and peritoneal macrophages. These processes were completely blocked by WT.3 (anti-CD18 mAb. The stimulation of binding thymocyte to macrophages was higher with the use of thymic macrophages,while the phagocytosis of these cells was higher in the presence of peritoneal macrophages. Conclusion. R-MC46 mAb recognized a new molecule expressed by rat macrophages. The antigen is most probably involved in β2 integrin-mediated adhesion and phagocytosis, as well as proinflammatory functions of macrophages.

  5. A Sequential Model of Host Cell Killing and Phagocytosis by Entamoeba histolytica

    Science.gov (United States)

    Sateriale, Adam; Huston, Christopher D.

    2011-01-01

    The protozoan parasite Entamoeba histolytica is responsible for invasive intestinal and extraintestinal amebiasis. The virulence of Entamoeba histolytica is strongly correlated with the parasite's capacity to effectively kill and phagocytose host cells. The process by which host cells are killed and phagocytosed follows a sequential model of adherence, cell killing, initiation of phagocytosis, and engulfment. This paper presents recent advances in the cytolytic and phagocytic processes of Entamoeba histolytica in context of the sequential model. PMID:21331284

  6. Lipoxins and Annexin-1: Resolution of Inflammation and Regulation of Phagocytosis of Apoptotic Cells

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    Michael Scannell

    2006-01-01

    Full Text Available Phagocytosis of apoptotic cells plays a pivotal role in developmental processes and in the resolution of inflammation. Failed or delayed clearance of apoptotic cells can result in chronic inflammation. Furthermore, clearance of apoptotic cells leads to release of anti-inflammatory cytokines. Recent evidence has shown that endogenous mediators can regulate such processes. In this article, we will review the recognition and signaling mechanisms involved in the phagocytosis of apoptotic cells as well as the role of endogenous compounds that play a relevant role in the modulation of inflammation. The first of these endogenous local mediators to be described are lipoxins (LXs. LXs and aspirin-triggered LXs (ATLs are considered to act as “braking signals” in inflammation, limiting the entrance of leukocytes to the site of inflammation through inhibition of neutrophil and eosinophil trafficking. LXs are actively involved in resolution of inflammation, stimulating nonphlogistic phagocytosis of apoptotic cells by macrophages. LXA4 and ATLs elicit cellular responses by interacting with a G protein -coupled receptor (ALXR that is expressed in various cell types. ALXR, originally identified as a low-affinity N-formyl-methionyl-leucyl-phenylalanine receptor-like 1, can bind pleiotropic ligands, i.e., both lipid and peptides, including the glucocorticoid-inducible protein, annexin-1. Interestingly, a role for annexin-1 in phagocytosis has recently emerged. Understanding the role and mechanism of the powerful anti-inflammatory and proresolution actions of endogenous compounds can be a useful tool in the development of potential therapeutics in resolving inflammatory diseases.

  7. Phagocytosis of Pseudomonas aeruginosa by polymorphonuclear leukocytes and monocytes: effect of cystic fibrosis serum.

    OpenAIRE

    Thomassen, M J; Demko, C A; Wood, R.E.; Sherman, J. M.

    1982-01-01

    It has been shown previously that serum from chronically infected patients with cystic fibrosis inhibits the phagocytosis of Pseudomonas aeruginosa by both normal and cystic fibrosis alveolar macrophages. In the present study, the ability of peripheral monocytes and polymorphonuclear leukocytes from normal volunteers and cystic fibrosis patients to phagocytize P. aeruginosa was shown not to be inhibited in the presence of serum from cystic fibrosis patients.

  8. Phagocytosis of Aspergillus fumigatus conidia by primary nasal epithelial cells in vitro

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    Khoufache Khaled

    2008-06-01

    Full Text Available Abstract Background Invasive aspergillosis, which is mainly caused by the fungus Aspergillus fumigatus, is an increasing problem in immunocompromised patients. Infection occurs by inhalation of airborne conidia, which are first encountered by airway epithelial cells. Internalization of these conidia into the epithelial cells could serve as a portal of entry for this pathogenic fungus. Results We used an in vitro model of primary cultures of human nasal epithelial cells (HNEC at an air-liquid interface. A. fumigatus conidia were compared to Penicillium chrysogenum conidia, a mould that is rarely responsible for invasive disease. Confocal microscopy, transmission electron microscopy, and anti-LAMP1 antibody labeling studies showed that conidia of both species were phagocytosed and trafficked into a late endosomal-lysosomal compartment as early as 4 h post-infection. In double immunolabeling experiments, the mean percentage of A. fumigatus conidia undergoing phagocytosis 4 h post-infection was 21.8 ± 4.5%. Using combined staining with a fluorescence brightener and propidium iodide, the mean rate of phagocytosis was 18.7 ± 9.3% and the killing rate 16.7 ± 7.5% for A. fumigatus after 8 h. The phagocytosis rate did not differ between the two fungal species for a given primary culture. No germination of the conidia was observed until 20 h of observation. Conclusion HNEC can phagocytose fungal conidia but killing of phagocytosed conidia is low, although the spores do not germinate. This phagocytosis does not seem to be specific to A. fumigatus. Other immune cells or mechanisms are required to kill A. fumigatus conidia and to avoid further invasion.

  9. P2X7 receptors mediate innate phagocytosis by human neural precursor cells and neuroblasts.

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    Lovelace, Michael D; Gu, Ben J; Eamegdool, Steven S; Weible, Michael W; Wiley, James S; Allen, David G; Chan-Ling, Tailoi

    2015-02-01

    During early human neurogenesis there is overproduction of neuroblasts and neurons accompanied by widespread programmed cell death (PCD). While it is understood that CD68(+) microglia and astrocytes mediate phagocytosis during target-dependent PCD, little is known of the cell identity or the scavenger molecules used to remove apoptotic corpses during the earliest stages of human neurogenesis. Using a combination of multiple-marker immunohistochemical staining, functional blocking antibodies and antagonists, we showed that human neural precursor cells (hNPCs) and neuroblasts express functional P2X7 receptors. Furthermore, using live-cell imaging, flow cytometry, phagocytic assays, and siRNA knockdown, we showed that in a serum-free environment, doublecortin(+) (DCX) neuroblasts and hNPCs can clear apoptotic cells by innate phagocytosis mediated via P2X7. We found that both P2X7(high) DCX(low) hNPCs and P2X7(high) DCX(high) neuroblasts, derived from primary cultures of human fetal telencephalon, phagocytosed targets including latex beads, apoptotic ReNcells, and apoptotic hNPC/neuroblasts. Pretreatment of neuroblasts and hNPCs with 1 mM adenosine triphosphate (ATP), 100 µM OxATP (P2X7 antagonist), or siRNA knockdown of P2X7 inhibited phagocytosis of these targets. Our results show that P2X7 functions as a scavenger receptor under serum-free conditions resembling those in early neurogenesis. This is the first demonstration that hNPCs and neuroblasts may participate in clearance of apoptotic corpses during pre target-dependent neurogenesis and mediate phagocytosis using P2X7 as a scavenger receptor.

  10. Antimicrobial prophylaxis in adults.

    Science.gov (United States)

    Enzler, Mark J; Berbari, Elie; Osmon, Douglas R

    2011-07-01

    Antimicrobial prophylaxis is commonly used by clinicians for the prevention of numerous infectious diseases, including herpes simplex infection, rheumatic fever, recurrent cellulitis, meningococcal disease, recurrent uncomplicated urinary tract infections in women, spontaneous bacterial peritonitis in patients with cirrhosis, influenza, infective endocarditis, pertussis, and acute necrotizing pancreatitis, as well as infections associated with open fractures, recent prosthetic joint placement, and bite wounds. Perioperative antimicrobial prophylaxis is recommended for various surgical procedures to prevent surgical site infections. Optimal antimicrobial agents for prophylaxis should be bactericidal, nontoxic, inexpensive, and active against the typical pathogens that can cause surgical site infection postoperatively. To maximize its effectiveness, intravenous perioperative prophylaxis should be administered within 30 to 60 minutes before the surgical incision. Antimicrobial prophylaxis should be of short duration to decrease toxicity and antimicrobial resistance and to reduce cost.

  11. Progress of research on antimicrobial agents and their application to textiles%抗菌防霉剂的研究进展及其在纺织品中的应用

    Institute of Scientific and Technical Information of China (English)

    郑皓; 徐少俊; 杨晓霞; 陈志龙

    2011-01-01

    This paper introduced the development of both domestic and overseas research of inorganic, organic and natural antimicrobial agents and their application to textiles, including antimicrobial agents of metal ionic, TiO2 photocatalytic oxides, metal / photocatalytic oxides nano-composite, inorganic/organic composite, biguanide compounds, N-halamine, phenylic acids, quaternary ammonium salts, quaternary phosphonium salts, and natural antimicrobial agents such as chitosan and its derivatives, with emphasis on quaternary ammonium salts and quaternary phosphonium salts. In addition, the antimicrobial treating methods for textiles were classified into polyblending, chemical modification of fiber, conjugate spinning, fiber finishing and textile finishing. The test methods for antimicrobial efficiency and safety of the agents were reviewed and the future development of antimicrobial agents was given.%介绍了国内外无机、有机、天然抗菌防霉剂的研究进展以及其在纺织品上的应用.具体包括金属离子型抗菌剂,TiO2等光催化氧化型抗菌剂,金属离子光催化氧化物型复合纳米抗菌剂,有机-无机复合抗菌剂,双胍类、卤代胺类、苯酚、季铵盐类、季鳞盐类等有机抗菌剂,壳聚糖及其衍生物等天然抗菌剂.着重介绍了季铵和季鳞盐类有机抗菌剂.对纤维和纺织品抗菌处理方法进行了分类,有共混纺丝法、纤维化学改性法、复合纺丝法、纤维整理法、纺织品后整理法.对抗菌防霉性及安全性检测方法进行了概述,并对抗菌剂的发展进行了展望.

  12. Active phagocytosis of Mycobacterium tuberculosis (H37Ra) by T lymphocytes (Jurkat cells).

    Science.gov (United States)

    Zhang, Min; Zhu, Qi; Shi, Ming; Liu, Yang; Ma, Lei; Yang, Yining; Feng, Dongyun; Dai, Wen; Zhang, Lin; Kang, Tao; Chen, Ping; He, Ying; Liu, Tingting; Zhao, Qing; Wang, Wenjing; Zhi, Jin; Feng, Guodong; Zhao, Gang

    2015-08-01

    This study aimed to co-culture Jurkat T lymphocytes with inactivated Mycobacterium tuberculosis (Mtb H37Ra), explore whether T lymphocytes could phagocytose H37Ra cells, and determine the underlying mechanism. Jurkat T lymphocytes were co-cultured with H37Ra cells, and confocal laser scanning microscopy, electron microscopy, and flow cytometry techniques were used to identify phagocytosis and elucidate its mechanism. After Jurkat T lymphocytes phagocytosed H37Ra cells, the cell body became larger, with abundant cytoplasm, the portion of the nucleus closest to the bacterium deformed, long and short pseudopodia were extended, and the folds of the cell membrane formed depressions that created phagocytic vesicles surrounding the bacterium. The macropinocytosis inhibitor amiloride and the cytoskeletal inhibitor cytochalasin D were found to inhibit phagocytic efficacy; serum complements might enhance phagocytosis through opsonization. Jurkat T lymphocytes could actively phagocytose inactivated Mtb via the macropinocytotic mechanism. Actin remodeling played an important role in the macropinocytotic process. Serum complements may regulate phagocytosis.

  13. A novel flow cytometric assay for measurement of In Vivo pulmonary neutrophil phagocytosis

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    Gentry-Nielsen Martha J

    2006-07-01

    Full Text Available Abstract Background Phagocytosis assays are traditionally performed in vitro using polymorphonuclear leukocytes (PMNs isolated from peripheral blood or the peritoneum and heat-killed, pre-opsonized organisms. These assays may not adequately mimic the environment within the infected lung. Our laboratory therefore has developed a flow cytometric in vivo phagocytosis assay that enables quantification of PMN phagocytosis of viable bacteria within the lungs of rats. In these studies, rats are injected transtracheally with lipopolysaccharide (LPS to recruit PMNs to their lungs. They are then infected with live 5(-and 6 carboxyfluorescein diacetate succinimidyl ester (CFDA/SE labeled type 3 Streptococcus pneumoniae. Bronchoalveolar lavage is performed and resident alveolar macrophages and recruited PMNs are labeled with monoclonal antibodies specific for surface epitopes on each cell type. Three color flow cytometry is utilized to identify the cell types, quantify recruitment, and determine uptake of the labeled bacteria. Results The viability of the alveolar macrophages and PMNs isolated from the lavage fluid was >95%. The values of the percentage of PMNs in the lavage fluid as well as the percentage of PMNs associated with CFSE-labeled S. pneumoniae as measured through flow cytometry showed a high degree of correlation with the results from manual counting of cytospin slides. Conclusion This assay is suitable for measuring bacterial uptake within the infected lung. It can be adapted for use with other organisms and/or animal model systems.

  14. Phagocytosis and hydrophobicity: a method of calculating contact angles based on the diameter of sessile drops.

    Science.gov (United States)

    Dahlgren, C; Sunqvist, T

    1981-01-01

    The correlation between the contact angle and degree of phagocytosis of different yeast particles has been investigated. To facilitate the estimation of the contact angle, we have tested the hypothesis that the shape of a small liquid drop put on a flat surface is that of a truncated sphere. By making this approximation it is possible to calculate the contact angle, i.e. the tangent to the drop in the 3-phase liquid/solid/air meeting point, by measuring the drop diameter. Known volumes of saline were put on different surfaces and the diameters of the drops were measured from above. Calculation of the contact angle with drops of different volumes, and comparison between expected and measured height of 10 microl drops, indicated that the assumption that the shape of a drop is that of a truncated sphere is valid. Monolayers of leukocytes was shown to give rise to a contact angle of 17.9 degrees. Particles with a lower contact angle than the phagocytic cells resisted phagocytosis, but opsonization of the particles with normal human serum rendered them susceptible to phagocytosis, conferring a higher contact angle than that of the phagocytic cells.

  15. MFG-E8 mediates primary phagocytosis of viable neurons during neuroinflammation.

    Science.gov (United States)

    Fricker, Michael; Neher, Jonas J; Zhao, Jing-Wei; Théry, Clotilde; Tolkovsky, Aviva M; Brown, Guy C

    2012-02-22

    Milk-fat globule EGF factor-8 (MFG-E8, SED1, lactadherin) is known to mediate the phagocytic removal of apoptotic cells by bridging phosphatidylserine (PS)-exposing cells and the vitronectin receptor (VR) on phagocytes. However, we show here that MFG-E8 can mediate phagocytosis of viable neurons during neuroinflammation induced by lipopolysaccharide (LPS), thereby causing neuronal death. In vitro, inflammatory neuronal loss is independent of apoptotic pathways, and is inhibited by blocking the PS/MFG-E8/VR pathway (by adding PS blocking antibodies, annexin V, mutant MFG-E8 unable to bind VR, or VR antagonist). Neuronal loss is absent in Mfge8 knock-out cultures, but restored by adding recombinant MFG-E8, without affecting inflammation. In vivo, LPS-induced neuronal loss is reduced in the striatum of Mfge8 knock-out mice or by coinjection of an MFG-E8 receptor (VR) inhibitor into the rat striatum. Our data show that blocking MFG-E8-dependent phagocytosis preserves live neurons, implying that phagocytosis actively contributes to neuronal death during brain inflammation.

  16. Target shape dependence in a simple model of receptor-mediated endocytosis and phagocytosis.

    Science.gov (United States)

    Richards, David M; Endres, Robert G

    2016-05-31

    Phagocytosis and receptor-mediated endocytosis are vitally important particle uptake mechanisms in many cell types, ranging from single-cell organisms to immune cells. In both processes, engulfment by the cell depends critically on both particle shape and orientation. However, most previous theoretical work has focused only on spherical particles and hence disregards the wide-ranging particle shapes occurring in nature, such as those of bacteria. Here, by implementing a simple model in one and two dimensions, we compare and contrast receptor-mediated endocytosis and phagocytosis for a range of biologically relevant shapes, including spheres, ellipsoids, capped cylinders, and hourglasses. We find a whole range of different engulfment behaviors with some ellipsoids engulfing faster than spheres, and that phagocytosis is able to engulf a greater range of target shapes than other types of endocytosis. Further, the 2D model can explain why some nonspherical particles engulf fastest (not at all) when presented to the membrane tip-first (lying flat). Our work reveals how some bacteria may avoid being internalized simply because of their shape, and suggests shapes for optimal drug delivery.

  17. High fat diet deviates PtC-specific B1 B cell phagocytosis in obese mice.

    Science.gov (United States)

    Vo, Hung; Chiu, Joanna; Allaimo, Danielle; Mao, Changchuin; Wang, Yaqi; Gong, Yuefei; Ow, Hooisweng; Porter, Tyrone; Zhong, Xuemei

    2014-12-01

    Phagocytosis had been attributed predominantly to "professional" phagocytes such as macrophages, which play critical roles in adipose tissue inflammation. However, recently, macrophage-like phagocytic activity has been reported in B1 B lymphocytes. Intrigued by the long-established correlation between high fat diet (HFD)-induced obesity and immune dysfunction, we investigated how HFD affects B1 B cell phagocytosis. A significant number of B1 B cells recognize phosphatidylcholine (PtC), a common phospholipid component of cell membrane. We report here that unlike macrophages, B1 B cells have a unique PtC-specific phagocytic function. In the presence of both PtC-coated and non-PtC control fluorescent nano-particles, B1 B cells from healthy lean mice selectively engulfed PtC-coated beads, whereas B1 B cells from HFD-fed obese mice non-discriminately phagocytosed both PtC-coated and control beads. Morphologically, B1 B cells from obese mice resembled macrophages, displaying enlarged cytosol and engulfed more beads. Our study suggests for the first time that HFD can affect B1 B cell phagocytosis, substantiating the link of HFD-induced obesity and immune deviation.

  18. Lyn Delivers Bacteria to Lysosomes for Eradication through TLR2-Initiated Autophagy Related Phagocytosis.

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    Xuefeng Li

    2016-01-01

    Full Text Available Extracellular bacteria, such as Pseudomonas aeruginosa and Klebsiella pneumoniae, have been reported to induce autophagy; however, the role and machinery of infection-induced autophagy remain elusive. We show that the pleiotropic Src kinase Lyn mediates phagocytosis and autophagosome maturation in alveolar macrophages (AM, which facilitates eventual bacterial eradication. We report that Lyn is required for bacterial infection-induced recruitment of autophagic components to pathogen-containing phagosomes. When we blocked autophagy with 3-methyladenine (3-MA or by depleting Lyn, we observed less phagocytosis and subsequent bacterial clearance by AM. Both morphological and biological evidence demonstrated that Lyn delivered bacteria to lysosomes through xenophagy. TLR2 initiated the phagocytic process and activated Lyn following infection. Cytoskeletal trafficking proteins, such as Rab5 and Rab7, critically facilitated early phagosome formation, autophagosome maturation, and eventual autophagy-mediated bacterial degradation. These findings reveal that Lyn, TLR2 and Rab modulate autophagy related phagocytosis and augment bactericidal activity, which may offer insight into novel therapeutic strategies to control lung infection.

  19. Effect of spiramycin on adhesiveness and phagocytosis of gram-positive cocci.

    Science.gov (United States)

    Desnottes, J F; Diallo, N; Moret, G

    1988-07-01

    Three strains of Staphylococcus aureus, serotype 18, Cowan I and serotype 66438, and different species of streptococci (Streptococcus pyogenes, Str, mutans, Str. sanguis and Str. faecalis) were tested for their adherence to buccal cells (as measured by interference contrast microscopy) and phagocytosis by rat polymorphonuclear leucocytes (PMNs) (as measured by fluorescence microscopy with a vital fluorochrome, acridine orange). Pretreatment of cocci with serial two-fold dilutions of spiramycin (from 1/2 to 1/1024 the MIC), increased the diameter of bacterial cells and decreased the adherence of staphylococci and streptococci to buccal cells. Exposure of streptococci to 1/4 the MIC of spiramycin led to an increase of the phagocytic capacity of PMNs. Pretreatment of PMNs with a therapeutic concentration (2 mg/l) also stimulated the phagocytosis of streptococci. Action of spiramycin on the phagocytosis of staphylococci varied according to the strain tested. Although in-vitro results cannot be directly compared with in-vivo data, it is of interest that spiramycin decreases adherence of different Gram-positive cocci and enhances phagocytic capacity of PMNs.

  20. αEnv-decorated phosphatidylserine liposomes trigger phagocytosis of HIV-virus-like particles in macrophages.

    Science.gov (United States)

    Gramatica, Andrea; Petazzi, Roberto A; Lehmann, Maik J; Ziomkowska, Joanna; Herrmann, Andreas; Chiantia, Salvatore

    2014-07-01

    Macrophages represent an important cellular target of HIV-1. Interestingly, they are also believed to play a potential role counteracting its infection. However, HIV-1 is known to impair macrophage immune functions such as antibody-mediated phagocytosis. Here, we present immunoliposomes that can bind HIV-1 virus-like particles (HIV-VLPs) while being specifically phagocytosed by macrophages, thus allowing the co-internalization of HIV-VLPs. These liposomes are decorated with anti-Env antibodies and contain phosphatidylserine (PS). PS mediates liposome internalization by macrophages via a mechanism not affected by HIV-1. Hence, PS-liposomes mimic apoptotic cells and are internalized into the macrophages due to specific recognition, carrying the previously bound HIV-VLPs. With a combination of flow cytometry, confocal live-cell imaging and electron microscopy we demonstrate that the PS-immunoliposomes presented here are able to elicit efficient HIV-VLPs phagocytosis by macrophages and might represent a new nanotechnological approach to enhance HIV-1 antigen presentation and reduce the ongoing inflammation processes. This team of authors demonstrate that specific phosphatidylserin immunoliposomes are able to elicit efficient phagocytosis of HIV-virus-like particle by macrophages and might represent a new nanomedicine approach to enhance HIV-1 antigen presentation and reduce ongoing inflammation processes. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Rab20 regulates phagosome maturation in RAW264 macrophages during Fc gamma receptor-mediated phagocytosis.

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    Youhei Egami

    Full Text Available Rab20, a member of the Rab GTPase family, is known to be involved in membrane trafficking, however its implication in FcγR-mediated phagocytosis is unclear. We examined the spatiotemporal localization of Rab20 during phagocytosis of IgG-opsonized erythrocytes (IgG-Es in RAW264 macrophages. By the live-cell imaging of fluorescent protein-fused Rab20, it was shown that Rab20 was transiently associated with the phagosomal membranes. During the early stage of phagosome formation, Rab20 was not localized on the membranes of phagocytic cups, but was gradually recruited to the newly formed phagosomes. Although Rab20 was colocalized with Rab5 to some extent, the association of Rab20 with the phagosomes persisted even after the loss of Rab5 from the phagosomal membranes. Then, Rab20 was colocalized with Rab7 and Lamp1, late endosomal/lysosomal markers, on the internalized phagosomes. Moreover, our analysis of Rab20 mutant expression revealed that the maturation of phagosomes was significantly delayed in cells expressing the GDP-bound mutant Rab20-T19N. These data suggest that Rab20 is an important component of phagosome and regulates the phagosome maturation during FcγR-mediated phagocytosis.

  2. A Toll/IL-1R/resistance domain-containing thioredoxin regulates phagocytosis in Entamoeba histolytica

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    Mancilla-Herrera Ismael

    2012-10-01

    Full Text Available Abstract Background Entamoeba histolytica is a protozoan parasite that infects humans and causes amebiasis affecting developing countries. Phagocytosis of epithelial cells, erythrocytes, leucocytes, and commensal microbiota bacteria is a major pathogenic mechanism used by this parasite. A Toll/IL-1R/Resistance (TIR domain-containing protein is required in phagocytosis in the social ameba Dictyostelium discoideum, an ameba closely related to Entamoeba histolytica in phylogeny. In insects and vertebrates, TIR domain-containing proteins regulate phagocytic and cell activation. Therefore, we investigated whether E. histolytica expresses TIR domain-containing molecules that may be involved in the phagocytosis of erythrocytes and bacteria. Methods Using in silico analysis we explored in Entamoeba histolytica databases for TIR domain containing sequences. After silencing TIR domain containing sequences in trophozoites by siRNA we evaluated phagocytosis of erythrocytes and bacteria. Results We identified an E. histolytica thioredoxin containing a TIR-like domain. The secondary and tertiary structure of this sequence exhibited structural similarity to TIR domain family. Thioredoxin transcripts silenced in E. histolytica trophozoites decreased erythrocytes and E. coli phagocytosis. Conclusion TIR domain-containing thioredoxin of E. histolytica could be an important element in erythrocytes and bacteria phagocytosis.

  3. Short-Term Regulation of FcγR-Mediated Phagocytosis by TLRs in Macrophages: Participation of 5-Lipoxygenase Products.

    Science.gov (United States)

    Pinheiro, Carla da S; Monteiro, Ana Paula T; Dutra, Fabiano F; Bozza, Marcelo T; Peters-Golden, Marc; Benjamim, Claudia F; Canetti, Claudio

    2017-01-01

    TLRs recognize a broad spectrum of microorganism molecules, triggering a variety of cellular responses. Among them, phagocytosis is a critical process for host defense. Leukotrienes (LTs), lipid mediators produced from 5-lipoxygenase (5-LO) enzyme, increase FcγR-mediated phagocytosis. Here, we evaluated the participation of TLR2, TLR3, TLR4, and TLR9 in FcγR-mediated phagocytosis and whether this process is modulated by LTs. Rat alveolar macrophages (AMs), murine bone marrow-derived macrophages (BMDMs), and peritoneal macrophages (PMs) treated with TLR2, TLR3, and TLR4 agonists, but not TLR9, enhanced IgG-opsonized sheep red blood cell (IgG-sRBC) phagocytosis. Pretreatment of AMs or BMDMs with drugs that block LT synthesis impaired the phagocytosis promoted by TLR ligands, and TLR potentiation was also abrogated in PMs and BMDMs from 5-LO(-/-) mice. LTB4 production induced by IgG engagement was amplified by TLR ligands, while cys-LTs were amplified by activation of TLR2 and TLR4, but not by TLR3. We also noted higher ERK1/2 phosphorylation in IgG-RBC-challenged cells when preincubated with TLR agonists. Furthermore, ERK1/2 inhibition by PD98059 reduced the phagocytic activity evoked by TLR agonists. Together, these data indicate that TLR2, TLR3, and TLR4 ligands, but not TLR9, amplify IgG-mediated phagocytosis by a mechanism which requires LT production and ERK-1/2 pathway activation.

  4. Fast disinfecting antimicrobial surfaces.

    Science.gov (United States)

    Madkour, Ahmad E; Dabkowski, Jeffery M; Nusslein, Klaus; Tew, Gregory N

    2009-01-20

    Silicon wafers and glass surfaces were functionalized with facially amphiphilic antimicrobial copolymers using the "grafting from" technique. Surface-initiated atom transfer radical polymerization (ATRP) was used to grow poly(butylmethacrylate)-co-poly(Boc-aminoethyl methacrylate) from the surfaces. Upon Boc-deprotection, these surfaces became highly antimicrobial and killed S. aureus and E. coli 100% in less than 5 min. The molecular weight and grafting density of the polymer were controlled by varying the polymerization time and initiator surface density. Antimicrobial studies showed that the killing efficiency of these surfaces was independent of polymer layer thickness or grafting density within the range of surfaces studied.

  5. Effect of silica and gold nanoparticles on macrophage proliferation, activation markers, cytokine production, and phagocytosis in vitro.

    Science.gov (United States)

    Bancos, Simona; Stevens, David L; Tyner, Katherine M

    2015-01-01

    The accumulation of durable nanoparticles (NPs) in macrophages following systemic administration is well described. The ultimate biological impact of this accumulation on macrophage function, however, is not fully understood. In this study, nontoxic doses of two durable NPs, SiO2 and Au, at particle sizes of ~10 nm and 300 nm were used to evaluate the effect of bioaccumulation on macrophage function in vitro using RAW 264.7 mouse macrophage-like cells as a model system. Cell proliferation, cell cycle, cytokine production, surface marker activation, and phagocytosis responses were evaluated through a panel of assays using flow cytometry and confocal microscopy. The most dramatic change in RAW 264.7 cell function was a reduction in phagocytosis as monitored by the uptake of Escherichia coli. Cells exposed to both 10 nm Au NPs and 10 nm SiO2 NPs showed ~50% decrease in phagocytosis, while the larger NPs caused a less dramatic reduction. In addition to modifying phagocytosis profiles, 10 nm SiO2 NPs caused changes in proliferation, cell cycle, and cell morphology. Au NPs had no effect on cell cycle, cytokine production, or surface markers and caused interference in phagocytosis in the form of quenching when the assay was performed via flow cytometry. Confocal microscopy analysis was used to minimize this interference and demonstrated that both sizes of Au NPs decreased the phagocytosis of E. coli. Overall, our results demonstrate that Au and SiO2 NP uptake by macrophages can influence macrophage phagocytosis in vitro without altering surface markers and cytokine production in vitro. While the biological impact of these findings remains unclear, our results indicate that bioaccumulation of durable NPs within the macrophages may lead to a suppression of bacterial uptake and possibly impair bactericidal activity.

  6. CD14-dependent monocyte isolation enhances phagocytosis of listeria monocytogenes by proinflammatory, GM-CSF-derived macrophages.

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    Caroline Neu

    Full Text Available Macrophages are an important line of defence against invading pathogens. Human macrophages derived by different methods were tested for their suitability as models to investigate Listeria monocytogenes (Lm infection and compared to macrophage-like THP-1 cells. Human primary monocytes were isolated by either positive or negative immunomagnetic selection and differentiated in the presence of granulocyte macrophage colony-stimulating factor (GM-CSF or macrophage colony-stimulating factor (M-CSF into pro- or anti-inflammatory macrophages, respectively. Regardless of the isolation method, GM-CSF-derived macrophages (GM-Mφ stained positive for CD206 and M-CSF-derived macrophages (M-Mφ for CD163. THP-1 cells did not express CD206 or CD163 following incubation with PMA, M- or GM-CSF alone or in combination. Upon infection with Lm, all primary macrophages showed good survival at high multiplicities of infection whereas viability of THP-1 was severely reduced even at lower bacterial numbers. M-Mφ generally showed high phagocytosis of Lm. Strikingly, phagocytosis of Lm by GM-Mφ was markedly influenced by the method used for isolation of monocytes. GM-Mφ derived from negatively isolated monocytes showed low phagocytosis of Lm whereas GM-Mφ generated from positively selected monocytes displayed high phagocytosis of Lm. Moreover, incubation with CD14 antibody was sufficient to enhance phagocytosis of Lm by GM-Mφ generated from negatively isolated monocytes. By contrast, non-specific phagocytosis of latex beads by GM-Mφ was not influenced by treatment with CD14 antibody. Furthermore, phagocytosis of Lactococcus lactis, Escherichia coli, human cytomegalovirus and the protozoan parasite Leishmania major by GM-Mφ was not enhanced upon treatment with CD14 antibody indicating that this effect is specific for Lm. Based on these observations, we propose macrophages derived by ex vivo differentiation of negatively selected human primary monocytes as the most

  7. Pharmacogenomics of antimicrobial agents.

    Science.gov (United States)

    Aung, Ar Kar; Haas, David W; Hulgan, Todd; Phillips, Elizabeth J

    2014-01-01

    Antimicrobial efficacy and toxicity varies between individuals owing to multiple factors. Genetic variants that affect drug-metabolizing enzymes may influence antimicrobial pharmacokinetics and pharmacodynamics, thereby determining efficacy and/or toxicity. In addition, many severe immune-mediated reactions have been associated with HLA class I and class II genes. In the last two decades, understanding of pharmacogenomic factors that influence antimicrobial efficacy and toxicity has rapidly evolved, leading to translational success such as the routine use of HLA-B*57:01 screening to prevent abacavir hypersensitivity reactions. This article examines recent advances in the field of antimicrobial pharmacogenomics that potentially affect treatment efficacy and toxicity, and challenges that exist between pharmacogenomic discovery and translation into clinical use.

  8. Animation of Antimicrobial Resistance

    Medline Plus

    Full Text Available ... showing how bacterial antimicrobial resistance can develop and spread. All FDA CVM produced material may be copied, ... Displays About NARMS Partners in Antibiotic Resistance and Food Safety Bacteria Tested NARMS at Work Meetings and ...

  9. Novel antimicrobial textiles

    Science.gov (United States)

    Cho, Unchin

    2003-10-01

    Many microorganisms can survive, and perhaps proliferate on textiles, generating adverse effects such as: disease transmission, odor generation, pH changes, staining, discoloration and loss of performance. These adverse effects may threaten users' health, deteriorate textile properties and degrade service quality. It may, therefore, be desirable to incorporate antimicrobials on textiles for controlling the growth of microorganisms. This dissertation focuses on the development of antimicrobial fibers and fabrics by integration of antimicrobials with these textiles. The applications of hydantoin-based halamines were mainly investigated in the research. The typical process is that hydantoin containing compounds are grafted onto textiles and transformed to halamine by chlorination. Hydantoin-based halamines are usually chloramines that release chlorine (Cl+) via cleavage of the -NCl functional group which attacks and kills microbes. The antimicrobial behavior is rechargeable many times by rinsing the fiber or fabric with chlorine-containing solution. Some quaternary ammonium type antimicrobials were also investigated in this research. The choice of integrating techniques is dependant on both the textile and antimicrobial compounds. In this dissertation, the nine approaches were studied for incorporating antimicrobial with various textiles: (1) co-extrusion of fibers with halamine precursor additive; (2) grafting of the quaternary ammonium compounds onto ethylene-co-acrylic acid fiber for creating quaternary ammonium type antimicrobial fiber; (3) entrapment of the additives in thermally bonded bicomponent nonwoven fabrics; (4) attaching antimicrobial additives to surfaces with latex adhesive coating; (5) grafting of antimicrobial compounds onto rubber latex via UV exposure; (6) reaction of halamine with needle-punched melamine formaldehyde nonwoven fabric and laminates; (7) coating melamine resin onto tent fabrics and laminates; (8) synthesis of super absorbent polymer

  10. Antimicrobial compounds in tears.

    Science.gov (United States)

    McDermott, Alison M

    2013-12-01

    The tear film coats the cornea and conjunctiva and serves several important functions. It provides lubrication, prevents drying of the ocular surface epithelia, helps provide a smooth surface for refracting light, supplies oxygen and is an important component of the innate defense system of the eye providing protection against a range of potential pathogens. This review describes both classic antimicrobial compounds found in tears such as lysozyme and some more recently identified such as members of the cationic antimicrobial peptide family and surfactant protein-D as well as potential new candidate molecules that may contribute to antimicrobial protection. As is readily evident from the literature review herein, tears, like all mucosal fluids, contain a plethora of molecules with known antimicrobial effects. That all of these are active in vivo is debatable as many are present in low concentrations, may be influenced by other tear components such as the ionic environment, and antimicrobial action may be only one of several activities ascribed to the molecule. However, there are many studies showing synergistic/additive interactions between several of the tear antimicrobials and it is highly likely that cooperativity between molecules is the primary way tears are able to afford significant antimicrobial protection to the ocular surface in vivo. In addition to effects on pathogen growth and survival some tear components prevent epithelial cell invasion and promote the epithelial expression of innate defense molecules. Given the protective role of tears a number of scenarios can be envisaged that may affect the amount and/or activity of tear antimicrobials and hence compromise tear immunity. Two such situations, dry eye disease and contact lens wear, are discussed here.

  11. Antibody-mediated phagocytosis contributes to the anti-tumor activity of the therapeutic antibody daratumumab in lymphoma and multiple myeloma

    DEFF Research Database (Denmark)

    Overdijk, M. B.; Verploegen, S.; Bogels, M.

    2015-01-01

    in MM and other hematological tumors, led us to investigate the contribution of antibody-dependent, macrophage-mediated phagocytosis to DARA's mechanism of action. Live cell imaging revealed that DARA efficiently induced macrophage-mediated phagocytosis, in which individual macrophages rapidly...... and sequentially engulfed multiple tumor cells. DARA-dependent phagocytosis by mouse and human macrophages was also observed in an in vitro flow cytometry assay, using a range of MM and Burkitt's lymphoma cell lines. Phagocytosis contributed to DARA's anti-tumor activity in vivo, in both a subcutaneous...

  12. 阳离子抗菌肽的杀菌及抗药性机制的研究进展%Research Progress on Cationic Antimicrobial Peptides in Antibacterial and Drug-resistant Mechanism

    Institute of Scientific and Technical Information of China (English)

    洪军; 胡建业

    2012-01-01

    阳离子抗菌肽是生物体抵御外源性病原微生物入侵而产生的一类小分子多肽,广泛分布于生物体内,具有广谱抗菌活性,是生物体先天性免疫防御系统的重要组成部分.除了具有抗细菌功能外,还具有抗真菌、抗原虫、抗病毒及抑制肿瘤细胞等功能,并对正常的真核细胞毒性较低,是新一代抗生素的理想替代品,但是同抗生素一样,部分细菌也能对抗菌肽产生抗药性.作者将从阳离子抗菌肽的杀菌及抗药性机制等方面进行阐述.%Cationic antimicrobial peptides were a class of small peptides with anti-extrogenous pathogen invasion. As an important component of congenital immune defense system against infections, they were widely distributed in vivo. It exhibited potent and broad-spectrum activities against both Gram-positive and Gram-negative bacteria, fungi, viruses, protozoa, and cancer cells,and normal eukaryotic cells with low toxicity. It was an ideal alternative to a new generation of antibiotics. However, the same as antibiotics, some bacteria were resistant to certain antimicrobial peptides. The antibacterial and drug-resistant mechanism of the cationic antimicrobial peptides were summarized in the article to provide certain reference.

  13. 病原微生物对抗菌肽抗性机制的研究进展%Progress in the Resistance Mechanisms of Pathogenic Microorganism against Antimicrobial Peptide

    Institute of Scientific and Technical Information of China (English)

    陈武; 黎定军; 丁彦; 张旭; 肖启明; 周清明

    2012-01-01

    抗菌肽(antimicrobial peptides,AMPs)是生物先天免疫系统的重要组成部分,可帮助宿主有效应对病原细菌、真菌和病毒等微生物的胁迫,被认为是医疗、食品加工和农业领域最具前途和潜力的抗生素替代物.病原微生物在与抗菌肽的互作中进化出了多种有针对性的抗性机制,从病原微生物对AMPs的感应与基因调控、细胞壁/膜成分的修饰、分泌蛋白酶降解及利用外排泵排出4个方面综述了国内外的研究进展,并对AMPs类制品的研究前景进行了讨论与展望.%As part of the innate immunity system of host organism, antimicrobial peptides ( AMPs) possess a wide spectrum of antimicrobial activity against eubacteria, fungi and eukaryotic parasites. AMPs are considered as one of potential alternates to the classical antibiotics in medicine, agriculture and food industry. The pathogenic microorganisms have correspondingly developed a defense system against the actions of AMPs during the co-evolution between the hosts and the pathogens. Recent discoveries on the resistance mechanism of pathogenic microorganism against AMPs, including sensing and gene regulation, modification of cell wall and/or plasma membrane, degradation of secreted proteases, as well as efflux pump by transporter proteins are discussed. Further, the perspectives of future research on AMP productions were proposed.

  14. [Heterogenous expression of antimicrobial peptides].

    Science.gov (United States)

    Song, Shanshan; Hu, Guobin; Dong, Xianzhi

    2009-12-01

    Antimicrobial peptides (AMPs), a class of short proteins with a broad spectrum of antibacterial activities, are isolated from a wide variety of animals, both vertebrates and invertebrates, and plants as well as from bacteria and fungi. They are a key component of the innate immune response in most multicellular organisms. Owing to their potent, broad-spectrum antibacterial activities and uneasy developing of drug resistance, these peptides are of great clinical significance. However, preparation of AMPs at a large scale is a severe challenge to the development of the commercial products. Undoubtedly, construction of high-level biological expression systems for the production of AMPs is the key in its clinical application process. Herein, we summarize the progress in researches on heterogenous expression of AMPs in prokaryotic expression systems and eukaryotic expression systems.

  15. Clearing the corpses: regulatory mechanisms, novel tools, and therapeutic potential of harnessing microglial phagocytosis in the diseased brain

    Directory of Open Access Journals (Sweden)

    Irune Diaz-Aparicio

    2016-01-01

    Full Text Available Apoptosis is a widespread phenomenon that occurs in the brain in both physiological and pathological conditions. Dead cells must be quickly removed to avoid the further toxic effects they exert in the parenchyma, a process executed by microglia, the brain professional phagocytes. Although phagocytosis is critical to maintain tissue homeostasis, it has long been either overlooked or indirectly assessed based on microglial morphology, expression of classical activation markers, or engulfment of artificial phagocytic targets in vitro. Nevertheless, these indirect methods present several limitations and, thus, direct observation and quantification of microglial phagocytosis is still necessary to fully grasp its relevance in the diseased brain. To overcome these caveats and obtain a comprehensive, quantitative picture of microglial phagocytosis we have developed a novel set of parameters. These parameters have allowed us to identify the different strategies utilized by microglia to cope with apoptotic challenges induced by excitotoxicity or inflammation. In contrast, we discovered that in mouse and human epilepsy microglia failed to find and engulf apoptotic cells, resulting in accumulation of debris and inflammation. Herein, we advocate that the efficiency of microglial phagocytosis should be routinely tested in neurodegenerative and neurological disorders, in order to determine the extent to which it contributes to apoptosis and inflammation found in these conditions. Finally, our findings point towards enhancing microglial phagocytosis as a novel therapeutic strategy to control tissue damage and inflammation, and accelerate recovery in brain diseases.

  16. Clearing the corpses:regulatory mechanisms, novel tools, and therapeutic potential of harnessing microglial phagocytosis in the diseased brain

    Institute of Scientific and Technical Information of China (English)

    Irune Diaz-Aparicio; Sol Beccari; Oihane Abiega; Amanda Sierra

    2016-01-01

    Apoptosis is a widespread phenomenon that occurs in the brain in both physiological and pathological conditions. Dead cells must be quickly removed to avoid the further toxic effects they exert in the pa-renchyma, a process executed by microglia, the brain professional phagocytes. Although phagocytosis is critical to maintain tissue homeostasis, it has long been either overlooked or indirectly assessed based on microglial morphology, expression of classical activation markers, or engulfment of artiifcial phagocytic targetsin vitro. Nevertheless, these indirect methods present several limitations and, thus, direct obser-vation and quantiifcation of microglial phagocytosis is still necessary to fully grasp its relevance in the diseased brain. To overcome these caveats and obtain a comprehensive, quantitative picture of microglial phagocytosis we have developed a novel set of parameters. hTese parameters have allowed us to identify the different strategies utilized by microglia to cope with apoptotic challenges induced by excitotoxicity or inlfammation. In contrast, we discovered that in mouse and human epilepsy microglia failed to ifnd and engulf apoptotic cells, resulting in accumulation of debris and inlfammation. Herein, we advocate that the effciency of microglial phagocytosis should be routinely tested in neurodegenerative and neuro-logical disorders, in order to determine the extent to which it contributes to apoptosis and inlfammation found in these conditions. Finally, our ifndings point towards enhancing microglial phagocytosis as a novel therapeutic strategy to control tissue damage and inlfammation, and accelerate recovery in brain diseases.

  17. Role of EhRab7A in phagocytosis of type 1 fimbriated E. coli by Entamoeba histolytica.

    Science.gov (United States)

    Verma, Kuldeep; Nozaki, Tomoyoshi; Datta, Sunando

    2016-12-01

    Entamoeba histolytica, the causative agent of amoebic colitis and liver abscess in human, ingests the intestinal bacteria and variety of host cells. Phagocytosis of bacteria by the amebic trophozoite has been reported to be important for the virulence of the parasite. Here, we set out to characterize different stages of phagocytosis of type 1 E. coli and investigated the role of a set of amoebic Rab GTPases in the process. The localizations of the Rab GTPases during different stages of the phagocytosis were investigated using laser scanning confocal microscopy and their functional relevance were determined using fluorescence activated cell sorter based assay as well as colony forming unit assay. Our results demonstrate that EhRab7A is localized on the phagosomes and involved in both early and late stages of type 1 E. coli phagocytosis. We further showed that the E. coli or RBC containing phagosomes are distinct from the large endocytic vacuoles in the parasite which are exclusively used to transport human holotransferrin and low density lipoprotein. Remarkably, type 1 E. coli uptake was found to be insensitive to cytochalasin D treatment, suggesting that the initial stage of E. coli phagocytosis is independent of the formation of actin filaments. © 2016 John Wiley & Sons Ltd.

  18. Anion Exchanger 2 Regulates Dectin-1-Dependent Phagocytosis and Killing of Candida albicans.

    Directory of Open Access Journals (Sweden)

    Katia Urso

    Full Text Available Anion exchanger 2 (Ae2; gene symbol, Slc4a2 is a plasma membrane Cl-/HCO3- exchanger expressed in the gastrointestinal tract, kidney and bone. We have previously shown that Ae2 is required for the function of osteoclasts, bone resorbing cells of the macrophage lineage, to maintain homeostatic cytoplasmic pH and electroneutrality during acid secretion. Macrophages require endosomal acidification for pathogen killing during the process known as phagocytosis. Chloride is thought to be the principal ion responsible for maintaining electroneutrality during organelle acidification, but whether Cl-/HCO3- exchangers such as Ae2 contribute to macrophage function is not known. In this study we investigated the role of Ae2 in primary macrophages during phagocytosis. We find that Ae2 is expressed in macrophages where it regulates intracellular pH and the binding of Zymosan, a fungal cell wall derivative. Surprisingly, the transcription and surface expression of Dectin-1, the major phagocytic receptor for Candida albicans (C. albicans and Zymosan, is reduced in the absence of Ae2. As a consequence, Zymosan-induced Tnfα expression is also impaired in Ae2-deficient macrophages. Similar to Ae2 deficiency, pharmacological alkalinization of lysosomal pH with bafilomycin A decreases both Dectin-1 mRNA and cell surface expression. Finally, Ae2-deficient macrophages demonstrate defective phagocytosis and killing of the human pathogenic fungus C. albicans. Our results strongly suggest that Ae2 is a critical factor in the innate response to C. albicans. This study represents an important contribution to a better understanding of how Dectin-1 expression and fungal clearance is regulated.

  19. Endotoxin-induced bovine mastitis: immunoglobulins, phagocytosis, and effect of flunixin meglumine.

    Science.gov (United States)

    Anderson, K L; Smith, A R; Shanks, R D; Whitmore, H L; Davis, L E; Gustafsson, B K

    1986-11-01

    Milk whey immunoglobulins (Ig) and phagocytosis of staphylococci by milk polymorphonuclear neutrophilic leukocytes (PMN) were measured in 12 cows (allotted to 6 pairs) during acute bovine mastitis induced by intramammary inoculation of endotoxin. Six of these cows (or 1 in each pair) were treated with flunixin meglumine and were compared with the others (given only saline solution). The endotoxin inoculation comprised 10 micrograms of Escherichia coli O26:B6 lipopolysaccharide injected into one of the rear quarters (mammae). Flunixin meglumine was administered parenterally at a dosage of 1.1 mg/kg every 8 hours (total of 7 doses) beginning at 2 hours after endotoxin was injected. Milk samples were obtained, and whey samples were prepared from each quarter of each cow 3 times before inoculation and at 2, 4, 8, 12, 24, 48, 72, 96, 120, 144, 168, and 336 hours after endotoxin was inoculated. Significant increases (P less than 0.05) in milk whey IgG1, IgG2, IgM, and IgA concentrations were observed in whey samples from endotoxin-inoculated quarters. Greatest relative increase was seen for IgG2. Increased whey Ig concentrations were not observed in quarters which were not inoculated with endotoxin. Concentrations of whey IgG1 and IgM in endotoxin-inoculated quarters were significantly (P less than 0.05) decreased in flunixin meglumine-treated cows, compared with those in saline solution-treated cows. Significant increases in phagocytosis of staphylococci by milk PMN were observed in whey samples from endotoxin-inoculated quarters. Significant differences in PMN phagocytosis were not found in whey samples from cows given flunixin meglumine when compared with whey samples from cows given saline solution.

  20. Pseudomonas aeruginosa elastase provides an escape from phagocytosis by degrading the pulmonary surfactant protein-A.

    Directory of Open Access Journals (Sweden)

    Zhizhou Kuang

    Full Text Available Pseudomonas aeruginosa is an opportunistic pathogen that causes both acute pneumonitis in immunocompromised patients and chronic lung infections in individuals with cystic fibrosis and other bronchiectasis. Over 75% of clinical isolates of P. aeruginosa secrete elastase B (LasB, an elastolytic metalloproteinase that is encoded by the lasB gene. Previously, in vitro studies have demonstrated that LasB degrades a number of components in both the innate and adaptive immune systems. These include surfactant proteins, antibacterial peptides, cytokines, chemokines and immunoglobulins. However, the contribution of LasB to lung infection by P. aeruginosa and to inactivation of pulmonary innate immunity in vivo needs more clarification. In this study, we examined the mechanisms underlying enhanced clearance of the ΔlasB mutant in mouse lungs. The ΔlasB mutant was attenuated in virulence when compared to the wild-type strain PAO1 during lung infection in SP-A+/+ mice. However, the ΔlasB mutant was as virulent as PAO1 in the lungs of SP-A⁻/⁻ mice. Detailed analysis showed that the ΔlasB mutant was more susceptible to SP-A-mediated opsonization but not membrane permeabilization. In vitro and in vivo phagocytosis experiments revealed that SP-A augmented the phagocytosis of ΔlasB mutant bacteria more efficiently than the isogenic wild-type PAO1. The ΔlasB mutant was found to have a severely reduced ability to degrade SP-A, consequently making it unable to evade opsonization by the collectin during phagocytosis. These results suggest that P. aeruginosa LasB protects against SP-A-mediated opsonization by degrading the collectin.

  1. Kinetic studies of Candida parapsilosis phagocytosis by macrophages and detection of intracellular survival mechanisms

    Directory of Open Access Journals (Sweden)

    Renata eToth

    2014-11-01

    Full Text Available Even though the number of Candida infections due to non-albicans species like C. parapsilosis has been increasing, little is known about their pathomechanisms. Certain aspects of C. parapsilosis and host interactions have already been investigated; however we lack information about the innate cellular responses towards this species. The aim of our project was to dissect and compare the phagocytosis of C. parapsilosis to C. albicans and to another Candida species C. glabrata by murine and human macrophages by live cell video microscopy. We broke down the phagocytic process into three stages: macrophage migration, engulfment of fungal cells and host cell killing after the uptake. Our results showed increased macrophage migration towards C. parapsilosis and we observed differences during the engulfment processes when comparing the three species. The engulfment time of C. parapsilosis was comparable to that of C. albicans regardless of the pseudohypha length and spatial orientation relative to phagocytes, while the rate of host cell killing and the overall uptake regarding C. parapsilosis showed similarities mainly with C. glabrata. Furthermore, we observed difference between human and murine phagocytes in the uptake of C. parapsilosis. UV-treatment of fungal cells had varied effects on phagocytosis dependent upon which Candida strain was used. Besides statistical analysis, live cell imaging videos showed that this species similarly to the other two also has the ability to survive in host cells via the following mechanisms: yeast replication, and pseudohypha growth inside of phagocytes, exocytosis of fungal cells and also abortion of host cell mitosis following the uptake. According to our knowledge this is the first study that provides a thorough examination of C. parapsilosis phagocytosis and reports intracellular survival mechanisms associated with this species.

  2. Acute toxicity and depression of phagocytosis in vivo by liposomes: influence of lysophosphatidylcholine.

    Science.gov (United States)

    Lutz, J; Augustin, A J; Jäger, L J; Bachmann, D; Brandl, M

    1995-01-01

    Small unilamellar phospholipid vesicles (liposomes), intended as drug carriers, have recently been demonstrated to reversibly depress phagocytic activity in rats when injected in a single high dose (2g of lipid per kg body weight) as revealed by the carbon clearance test. Depression of the phagocytic function was found to vary widely depending on the lipid used [M. Brandl et al., Pharm. Pharmacol. Lett., 4 (1) 1-4, 1994]. This study has now been extended in two directions: Firstly, liposomes made of the same type of lipid but different batches of raw material were compared in terms of their influence on phagocytosis as well as for their contents of impurities. The test revealed great variability of RES suppression between different batches of hydrogenated soy PC, whereas the reproducibility of the carbon clearance test was satisfactory with liposomes made of a single batch of raw material. Thin layer chromatographic analyses of the used phosphatidylcholines (PCs) and limulus tests on lipopolysaccharides revealed lysophosphatidylcholine (lysoPC) as the only impurity which showed parallels with the observed differences in phagocytosis. Secondly by "spiking" phosphatidylcholine with increasing amounts of lysoPC the latter could be proven to enhance RES depression by liposomes in a dose-dependent manner. At the same time a strong and dose-limiting increase in acute toxicity of PC vesicles was observed with increasing contents of lysoPC. However, in cholesterol-containing vesicles lysoPC-spiking did not significantly alter their behaviour, for lysoPC contents of up to 10%. Only PC/cholesterol-vesicles containing lysoPC contents as high as 15% provoked enhanced RES depression and toxicity compared to lysoPC-free vesicles. LysoPC and cholesterol in liposomes are known to play a destabilizing and stabilizing role respectively within liposomal bilayers which might influence recognition and uptake of vesicles by macrophages and thus modulation of phagocytosis.

  3. Research progress on antioxidant and antimicrobial effect of Schisandra chinensis (Turcz.) Baill.%五味子抗氧化和抑菌作用的研究进展

    Institute of Scientific and Technical Information of China (English)

    刘丽; 赵春苏; 马永全; 胡林子; 于新

    2011-01-01

    对五味子的抗氧化和抑菌作用进行了综述,结果表明现有的研究成果不能确定五味子抑菌成分,其抗氧化和抑菌作用机理也不明了,需要更深入的研究.同时对五味子在医药、保健品、食品等方面的应用进行了展望.%The antioxidant and antimicrobial effect of Schisandra chinensis (Turcz.) Baill. were reviewed. The results showed that antibacterial component of Schisandra chinensis ( Turcz. ) Baill. was uncertainty, and antioxidant and antimicrobial mechanism of Schisandra chinensis (Turcz.) Baill. were unclear at present. It was very necessary to conduct in-depth study. The prospects of Schisandra chinensis (Turcz.) Baill. applied in medicine, health products, food were put forward, too.

  4. Impaired neonatal macrophage phagocytosis is not explained by overproduction of prostaglandin E2

    Directory of Open Access Journals (Sweden)

    Ballinger Megan N

    2011-12-01

    Full Text Available Abstract Background Neonates and young infants manifest increased susceptibility to bacterial, viral and fungal lung infections. Previous work has identified a role for eicosanoids in mediating host defense functions of macrophages. This study examines the relationship between alveolar macrophage (AM host defense and production of lipid mediators during the neonatal period compared to adult AMs. Methods AMs were harvested from young (day 7 and day 14 and adult (~10 week rats. The functionality of these cells was assessed by examining their ability to phagocytose opsonized targets, produce cytokines, eicosanoids and intracellular cAMP measured by enzyme immunoassays, and gene expression of proteins, enzymes and receptors essential for eicosanoid generation and phagocytosis measured by real time RT-PCR. Results AMs from young animals (day 7 and 14 were defective in their ability to phagocytose opsonized targets and produce tumor necrosis factor (TNF- α. In addition, young AMs produce more prostaglandin (PG E2, a suppressor of host defense, and less leukotriene (LT B4, a promoter of host defense. Young AMs express higher levels of enzymes responsible for the production of PGE2 and LTB4; however, there was no change in the expression of E prostanoid (EP receptors or LT receptors. Despite the similar EP profiles, young AMs are more responsive to PGE2 as evidenced by their increased production of the important second messenger, cyclic AMP. In addition, young AMs express higher levels of PDE3B and lower levels of PDE4C compared to adult AMs. However, even though the young AMs produced a skewed eicosanoid profile, neither the inhibition of PGE2 by aspirin nor the addition of exogenous LTB4 rescued the defective opsonized phagocytosis. Examination of a receptor responsible for mediating opsonized phagocytosis showed a significant decrease in the gene expression levels of the Fcgamma receptor in young (day 7 AMs compared to adult AMs. Conclusion These

  5. Phagocytosis and intracellular killing of Candida albicans by murine polymorphonuclear neutrophils.

    Science.gov (United States)

    Vonk, Alieke G; Netea, Mihai G; Kullberg, Bart Jan

    2012-01-01

    Polymorphonuclear neutrophils (PMNs) are important phagocytes in the control of Candida infections. The phagocytic contribution of PMNs to host defence can by assessed by various methods, such as microbiological assays. However, assessment and definition of intracellular killing capacity can be a source of considerable confusion. A comparison of the growth of Candida in the presence of PMN with the growth of Candida in phagocyte-free suspensions may lead to an overestimation of killing capacity because PMNs can use both intracellular and extracellular killing mechanisms. Here, we describe the use of an adherent monolayer of exudate peritoneal PMNs that is used to differentiate between the process of phagocytosis and intracellular killing.

  6. Ability of Staphylococcus aureus coagulase genotypes to resist neutrophil bactericidal activity and phagocytosis

    DEFF Research Database (Denmark)

    Aarestrup, Frank Møller; Scott, N. L.; Sordillo, L. M.

    1994-01-01

    This study investigated the functional capabilities of neutrophils against different Staphylococcus aureus genotypes isolated from cows with mastitis. Six strains of S. aureus were chosen for use in the study, two with a common genotype, two with an intermediate genotype, and two with a rare......; rare type, 10.5/cell). These findings suggest that one of the reasons for the variation in prevalence of different genotypes of S. aureus in the mammary gland is due to the superior ability of some types to resist phagocytosis and/or killing by bovine neutrophils...

  7. Non-degradable contrast agent with selective phagocytosis for cellular and hepatic magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Fei-Yan [Nanchang University, College of Chemistry (China); Gu, Zhe-Jia [Nanchang University, Institute for Advanced Study (China); Zhao, Dawen [UT Southwestern Medical Center, Department of Radiology (United States); Tang, Qun, E-mail: tangqun@ncu.edu.cn [Nanchang University, Institute for Advanced Study (China)

    2015-09-15

    Degradation is the long-existing toxic issue of metal-containing inorganic medicine. In this paper, we fully investigated the degradation of dextran-coated KMnF{sub 3} nanocube in the in vitro and in vivo surroundings. Different from the general decomposing and ion releasing events, this special agent is resistant to acidic environment, as well as ion exchange. Non-degradability was proved by simulated and real cellular experiments. Moreover, it can be engulfed in the macrophage cells and kept stable in the lysosome. Due to its stability and highly selective phagocytosis, implanted liver cancer can be clearly visualized after administration.

  8. Myelin down-regulates myelin phagocytosis by microglia and macrophages through interactions between CD47 on myelin and SIRPα (signal regulatory protein-α on phagocytes

    Directory of Open Access Journals (Sweden)

    Reichert Fanny

    2011-03-01

    Full Text Available Abstract Background Traumatic injury to axons produces breakdown of axons and myelin at the site of the lesion and then further distal to this where Wallerian degeneration develops. The rapid removal of degenerated myelin by phagocytosis is advantageous for repair since molecules in myelin impede regeneration of severed axons. Thus, revealing mechanisms that regulate myelin phagocytosis by macrophages and microglia is important. We hypothesize that myelin regulates its own phagocytosis by simultaneous activation and down-regulation of microglial and macrophage responses. Activation follows myelin binding to receptors that mediate its phagocytosis (e.g. complement receptor-3, which has been previously studied. Down-regulation, which we test here, follows binding of myelin CD47 to the immune inhibitory receptor SIRPα (signal regulatory protein-α on macrophages and microglia. Methods CD47 and SIRPα expression was studied by confocal immunofluorescence microscopy, and myelin phagocytosis by ELISA. Results We first document that myelin, oligodendrocytes and Schwann cells express CD47 without SIRPα and further confirm that microglia and macrophages express both CD47 and SIRPα. Thus, CD47 on myelin can bind to and subsequently activate SIRPα on phagocytes, a prerequisite for CD47/SIRPα-dependent down-regulation of CD47+/+ myelin phagocytosis by itself. We then demonstrate that phagocytosis of CD47+/+ myelin is augmented when binding between myelin CD47 and SIRPα on phagocytes is blocked by mAbs against CD47 and SIRPα, indicating that down-regulation of phagocytosis indeed depends on CD47-SIRPα binding. Further, phagocytosis in serum-free medium of CD47+/+ myelin is augmented after knocking down SIRPα levels (SIRPα-KD in phagocytes by lentiviral infection with SIRPα-shRNA, whereas phagocytosis of myelin that lacks CD47 (CD47-/- is not. Thus, myelin CD47 produces SIRPα-dependent down-regulation of CD47+/+ myelin phagocytosis in phagocytes

  9. Phagocytosis of Collagen Fibrils by Fibroblasts In Vivo is Independent of the uPARAP/Endo180 Receptor

    DEFF Research Database (Denmark)

    Sprangers, Sara; Behrendt, Niels; Engelholm, Lars

    2017-01-01

    As a crucial step in ECM remodeling, collagen degradation occurs through different processes, including both extracellular and intracellular degradation. The extracellular pathways of collagen degradation require secretion of collagenolytic proteases, whereas intracellular collagen degradation...... occurs in the lysosomal compartment after uptake, involving either pre-cleaved or intact fibrillar collagen. The endocytic collagen receptor uPARAP/Endo180 plays an important role in internalization of large collagen degradation products, whereas its role in the phagocytosis of fibrillar collagen has...... been debated. In fact, the role of this receptor in regular collagen phagocytosis in vivo has not been established. In this study, we have studied the role of uPARAP in the phagocytosis of collagen fibrils in vivo by analyzing different connective tissues of mice lacking uPARAP. Using transmission...

  10. HIV-1 inhibits phagocytosis and inflammatory cytokine responses of human monocyte-derived macrophages to P. falciparum infected erythrocytes.

    Directory of Open Access Journals (Sweden)

    Louise E Ludlow

    Full Text Available HIV-1 infection increases the risk and severity of malaria by poorly defined mechanisms. We investigated the effect of HIV-1(Ba-L infection of monocyte-derived macrophages (MDM on phagocytosis of opsonised P. falciparum infected erythrocytes (IE and subsequent proinflammatory cytokine secretion. Compared to mock-infected MDM, HIV-1 infection significantly inhibited phagocytosis of IE (median (IQR (10 (0-28 versus (34 (27-108; IE internalised/100 MDM; p = 0.001 and decreased secretion of IL-6 (1,116 (352-3,387 versus 1,552 (889-6,331; pg/mL; p = 0.0078 and IL-1β (16 (7-21 versus 33 (27-65; pg/mL; p = 0.0078. Thus inadequate phagocytosis and cytokine production may contribute to impaired control of malaria in HIV-1 infected individuals.

  11. The antimicrobial resistance crisis: management through gene monitoring

    Science.gov (United States)

    2016-01-01

    Antimicrobial resistance (AMR) is an acknowledged crisis for humanity. Its genetic origins and dire potential outcomes are increasingly well understood. However, diagnostic techniques for monitoring the crisis are currently largely limited to enumerating the increasing incidence of resistant pathogens. Being the end-stage of the evolutionary process that produces antimicrobial resistant pathogens, these measurements, while diagnostic, are not prognostic, and so are not optimal in managing this crisis. A better test is required. Here, using insights from an understanding of evolutionary processes ruling the changing abundance of genes under selective pressure, we suggest a predictive framework for the AMR crisis. We then discuss the likely progression of resistance for both existing and prospective antimicrobial therapies. Finally, we suggest that by the environmental monitoring of resistance gene frequency, resistance may be detected and tracked presumptively, and how this tool may be used to guide decision-making in the local and global use of antimicrobials. PMID:27831476

  12. Antimicrobial Resistant Streptococcus pneumoniae

    Directory of Open Access Journals (Sweden)

    B Khanal

    2010-09-01

    Full Text Available Introduction: Pneumococcal infections are important cause of morbidity and mortality. Knowledge of antimicrobial susceptibility patterns plays important role in the selection of appropriate therapy. Present study was undertaken to analyze the susceptibility patterns of pneumococcal isolates against commonly used antimicrobials with special reference to determination of minimum inhibitory concentration (MIC of penicillin in a tertiary care hospital in eastern Nepal. Methods: Twenty-six strains of S. pneumoniae isolated from various clinical specimens submitted to microbiology laboratory were evaluated. All isolates were tested for antimicrobial susceptibility by disk diffusion method. MIC of penicillin was tested by broth dilution method. Results: Of the total isolates 19 (73% were from invasive infections. Seven isolates were resistant to cotrimoxazole. No resistance to penicillin was seen in disk diffusion testing. Less susceptibility to penicillin (MIC 0.1-1.0 mg/L was observed in five (17% isolates. High level resistance to penicillin was not detected. One isolate was multidrug resistant. Conclusions: S. pneumoniaeisolates with intermediate resistance to penicillin prevail in Tertiary Care Hospital in eastern Nepal, causing invasive and noninvasive infections. As intermediate resistance is not detected in routine susceptibility testing, determination of MIC is important. It helps not only in the effective management of life threatening infections but is also essential in continuous monitoring and early detection of resistance. In addition, further study on pneumococcal infections, its antimicrobial resistance profile and correlation with clinical and epidemiological features including serotypes and group prevalence is recommended in future. Keywords: antimicrobial susceptibility pattern, penicillin, Streptococcus pneumoniae.

  13. Antimicrobials, stress and mutagenesis.

    Directory of Open Access Journals (Sweden)

    Alexandro Rodríguez-Rojas

    2014-10-01

    Full Text Available Cationic antimicrobial peptides are ancient and ubiquitous immune effectors that multicellular organisms use to kill and police microbes whereas antibiotics are mostly employed by microorganisms. As antimicrobial peptides (AMPs mostly target the cell wall, a microbial 'Achilles heel', it has been proposed that bacterial resistance evolution is very unlikely and hence AMPs are ancient 'weapons' of multicellular organisms. Here we provide a new hypothesis to explain the widespread distribution of AMPs amongst multicellular organism. Studying five antimicrobial peptides from vertebrates and insects, we show, using a classic Luria-Delbrück fluctuation assay, that cationic antimicrobial peptides (AMPs do not increase bacterial mutation rates. Moreover, using rtPCR and disc diffusion assays we find that AMPs do not elicit SOS or rpoS bacterial stress pathways. This is in contrast to the main classes of antibiotics that elevate mutagenesis via eliciting the SOS and rpoS pathways. The notion of the 'Achilles heel' has been challenged by experimental selection for AMP-resistance, but our findings offer a new perspective on the evolutionary success of AMPs. Employing AMPs seems advantageous for multicellular organisms, as it does not fuel the adaptation of bacteria to their immune defenses. This has important consequences for our understanding of host-microbe interactions, the evolution of innate immune defenses, and also sheds new light on antimicrobial resistance evolution and the use of AMPs as drugs.

  14. Bispecific-armed, interferon gamma-primed macrophage-mediated phagocytosis of malignant non-Hodgkin's lymphoma.

    Science.gov (United States)

    Ely, P; Wallace, P K; Givan, A L; Graziano, R F; Guyre, P M; Fanger, M W

    1996-05-01

    To show that macrophages can be effectively targeted against malignant B cells, bispecific antibodies (BsAb) were constructed from two antibodies having specificity for the high-affinity Fc receptor for IgG (Fc gamma RI/CD64) and the B-cell differentiation antigens CD19 and CD37. Using a flow cytometry-based assay and confocal imaging, we show that these constructs mediated significant phagocytosis of B lymphocytes by macrophages that could be enhanced with interferon gamma (IFN gamma) and IFN gamma in combination with macrophage colony-stimulating factor. BsAb-dependent phagocytosis was triggered through Fc gamma RI and could be blocked only by using F(ab')2 fragments from the parent molecule or by cross-linking Fc gamma RI. BsAb-dependent phagocytosis was not blocked by antibodies to the other Fc receptors, Fc gamma RII and Fc gamma RIII. Because these antibody constructs bind to an epitope outside the Fc gamma RI ligand binding site, we show that autologous serum, polyclonal IgG, and monomeric IgG1 did not block BsAb-dependent phagocytosis, whereas autologous serum and the IgG fractions blocked parent molecule monoclonal antibody-dependent phagocytosis due to the avid binding of monomeric IgG to Fc gamma RI. Finally, BsAb-mediated phagocytosis was effective against the malignant B cells of patients with mantle cell lymphoma, prolymphocytic leukemia, and chronic lymphocytic leukemia. Based on these studies, we propose that BsAbs may provide an effective means of immunomodulation for patients with B-cell malignancies.

  15. Short-Term Regulation of FcγR-Mediated Phagocytosis by TLRs in Macrophages: Participation of 5-Lipoxygenase Products

    Directory of Open Access Journals (Sweden)

    Carla da S. Pinheiro

    2017-01-01

    Full Text Available TLRs recognize a broad spectrum of microorganism molecules, triggering a variety of cellular responses. Among them, phagocytosis is a critical process for host defense. Leukotrienes (LTs, lipid mediators produced from 5-lipoxygenase (5-LO enzyme, increase FcγR-mediated phagocytosis. Here, we evaluated the participation of TLR2, TLR3, TLR4, and TLR9 in FcγR-mediated phagocytosis and whether this process is modulated by LTs. Rat alveolar macrophages (AMs, murine bone marrow-derived macrophages (BMDMs, and peritoneal macrophages (PMs treated with TLR2, TLR3, and TLR4 agonists, but not TLR9, enhanced IgG-opsonized sheep red blood cell (IgG-sRBC phagocytosis. Pretreatment of AMs or BMDMs with drugs that block LT synthesis impaired the phagocytosis promoted by TLR ligands, and TLR potentiation was also abrogated in PMs and BMDMs from 5-LO−/− mice. LTB4 production induced by IgG engagement was amplified by TLR ligands, while cys-LTs were amplified by activation of TLR2 and TLR4, but not by TLR3. We also noted higher ERK1/2 phosphorylation in IgG-RBC-challenged cells when preincubated with TLR agonists. Furthermore, ERK1/2 inhibition by PD98059 reduced the phagocytic activity evoked by TLR agonists. Together, these data indicate that TLR2, TLR3, and TLR4 ligands, but not TLR9, amplify IgG-mediated phagocytosis by a mechanism which requires LT production and ERK-1/2 pathway activation.

  16. Phagocytosis stimulates alternative glycosylation of macrosialin (mouse CD68), a macrophage-specific endosomal protein.

    Science.gov (United States)

    da Silva, R P; Gordon, S

    1999-03-15

    Macrosialin (mouse CD68), a macrophage-specific member of the lysosomal-associated membrane protein family, displays N-linked glycosylation and a heavily sialylated, mucin-like domain. We show that phagocytosis of zymosan by inflammatory peritoneal macrophages potently alters glycan processing of macrosialin in vitro. The phagocytic glycoform is not induced by other forms of endocytosis and depends on particle internalization. Zymosan uptake does not influence macrosialin protein synthesis, but increases the specific incorporation of D-[2-3H]mannose, D-[6-3H]galactose, N-acetyl-D-[1-3H]glucosamine and L-[5,6-3H]fucose by 2-15-fold. The phagocytic glycoform displays increased binding of agglutinins from peanut, Amaranthus caudatus and Galanthus nivalis, whereas binding of the sialic-acid-specific Maakia amurensis agglutinin is slightly reduced. Digestion by N-Glycanase abolishes the incorporation of [3H]mannose label and Galanthus nivalis agglutinin binding activity, but preserves the incorporation of galactose and N-acetylglucosamine and specific lectin binding. We also show that phagocytosis increases the complexity and length of O-linked chains. The data presented highlight the importance of differential glycosylation in the biology of macrosialin, phagosomes and macrophages in general.

  17. Alterations in the protein pattern of subcellular fractions isolated from Paramecium cells suppressed in phagocytosis.

    Science.gov (United States)

    Surmacz, L; Wiejak, J; Wyroba, E

    2001-01-01

    SDS-PAGE and quantitative densitometric analysis revealed alterations in the protein pattern of subcellular fractions (100,000 x g) isolated from Paramecium aurelia (299s axenic) cells suppressed in phagocytosis as compared with the control. Two different agents were used to block phagocytosis: the beta-adrenergic antagonist-1-propranolol (200 microM) and inhibitor of calmodulin-dependent processes--trifluoperazine (20 microM). More than 40 polypeptides were identified in the cytosolic (soluble) fractions S1 and S2. A considerable decrease in band intensity was found for three polypeptides: by 60% for 87 kDa band, 52% for 75 kDa and 37% for 42 kDa in comparison to the control, when S2 fractions from propranolol-treated cells of equal load were quantified. TFP treatment evoked only a small decrease in the intensity of the same bands: 9%, 10% and 6%, respectively. The 42 kDa band was identified by Western blot analysis and chemiluminiscent detection to be actin. This result suggests that actin may be a primary target of pharmacological agents used in this study to inhibit Paramecium phagocytic activity.

  18. Histamine H3 receptor in primary mouse microglia inhibits chemotaxis, phagocytosis, and cytokine secretion.

    Science.gov (United States)

    Iida, Tomomitsu; Yoshikawa, Takeo; Matsuzawa, Takuro; Naganuma, Fumito; Nakamura, Tadaho; Miura, Yamato; Mohsen, Attayeb S; Harada, Ryuichi; Iwata, Ren; Yanai, Kazuhiko

    2015-07-01

    Histamine is a physiological amine which initiates a multitude of physiological responses by binding to four known G-protein coupled histamine receptor subtypes as follows: histamine H1 receptor (H1 R), H2 R, H3 R, and H4 R. Brain histamine elicits neuronal excitation and regulates a variety of physiological processes such as learning and memory, sleep-awake cycle and appetite regulation. Microglia, the resident macrophages in the brain, express histamine receptors; however, the effects of histamine on critical microglial functions such as chemotaxis, phagocytosis, and cytokine secretion have not been examined in primary cells. We demonstrated that mouse primary microglia express H2 R, H3 R, histidine decarboxylase, a histamine synthase, and histamine N-methyltransferase, a histamine metabolizing enzyme. Both forskolin-induced cAMP accumulation and ATP-induced intracellular Ca(2+) transients were reduced by the H3 R agonist imetit but not the H2 R agonist amthamine. H3 R activation on two ubiquitous second messenger signalling pathways suggests that H3 R can regulate various microglial functions. In fact, histamine and imetit dose-dependently inhibited microglial chemotaxis, phagocytosis, and lipopolysaccharide (LPS)-induced cytokine production. Furthermore, we confirmed that microglia produced histamine in the presence of LPS, suggesting that H3 R activation regulate microglial function by autocrine and/or paracrine signalling. In conclusion, we demonstrate the involvement of histamine in primary microglial functions, providing the novel insight into physiological roles of brain histamine.

  19. Phagocytosis by thrombocytes is a conserved innate immune mechanism in lower vertebrates

    Directory of Open Access Journals (Sweden)

    Takahiro eNagasawa

    2014-09-01

    Full Text Available Thrombocytes, nucleated hemostatic blood cells of nonmammalian vertebrates, are regarded as the functional equivalent of anucleated mammalian platelets. Additional immune functions, including phagocytosis, have also been suggested for thrombocytes, but no conclusive molecular or cellular experimental evidence for their potential ingestion and clearance of infiltrating microbes has been provided till date. In the present study, we demonstrate the active phagocytic ability of thrombocytes in lower vertebrates using teleost fishes and amphibian models. Ex vivo, common carp thrombocytes were able to ingest live bacteria as well as latex beads (0.5–3 μm in diameter and kill the bacteria. In vivo, we found that thrombocytes represented nearly half of the phagocyte population in the common carp total peripheral blood leukocyte pool. Phagocytosis efficiency was further enhanced by serum opsonization. Particle internalization led to phagolysosome fusion and killing of internalized bacteria, pointing to a robust ability for microbe elimination. We find that this potent phagocytic activity is shared across teleost (Paralichthys olivaceus and amphibian (Xenopus laevis models examined, implying its conservation throughout the lower vertebrate lineage. Our results provide novel insights into the dual nature of thrombocytes in the immune and homeostatic response and further provide a deeper understanding of the potential immune function of mammalian platelets based on the conserved and vestigial functions.

  20. New combined assay of phagocytosis and intracellular killing of Escherichia coli by polymorphonuclear leukocytes

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, P.J.; Ford, J.M. (Saint Bartholomew' s Hospital, London (UK))

    1982-03-12

    A new combined radiometric assay is described in which adherence, and phagocytosis and killing of Escherichia coli by human polymorphonuclear leucocytes (PMN) are simultaneously measured in the same sample. Pure monolayers of PMN in Petri dishes are allowed to ingest (/sup 14/C)phenylalanine labelled E. coli and excess bacteria are removed by washing. A period of incubation allows intracellular killing to occur while polymyxin-B is added to half the dishes to kill extracellular bacteria. The remaining viable bacteria in all dishes are labelled with (/sup 3/H)thymidine. The number of ingested bacteria and the percentage of intracellular organisms killed is determined from the /sup 14/C and /sup 3/H counts by a simple subtraction technique. By performing protein assays on representative monolayers, the number of PMN adhered in the monolayers and hence the mean bacterial uptake per PMN is estimated. The assay detected killing efficiencies reduced below the normal range, in monolayers treated with sodium azide, phenylbutazone, in polymorphonuclear leukocytes from patients with chronic granulomatous disease, and in immature neutrophils from the promyelocytic leukaemic cell line, HL60. The assay was adapted to measure phagocytosis and killing by cells in suspension.

  1. Resistance of fluorescent-labelled Actinobacillus actinomycetemcomitans strains to phagocytosis and killing by human neutrophils.

    Science.gov (United States)

    Permpanich, Piyanuj; Kowolik, Michael J; Galli, Dominique M

    2006-01-01

    Neutrophils are initially the predominant cells involved in the host defence of bacterial infections, including periodontal disease. Aggressive periodontitis is associated with Actinobacillus actinomycetemcomitans, a Gram-negative capnophilic microorganism. Infections caused by A. actinomycetemcomitans are not resolved by the host immune response despite the accumulation of neutrophils at the site of inflammation. To better understand the role of natural host defence mechanisms in A. actinomycetemcomitans infections, the interaction of phenotypically diverse strains of this pathogen with human neutrophils was assessed directly using techniques such as genetic labelling with the gene for green fluorescent protein, fluorescence-activated cell sorting and fluorescence imaging. The study included clinical isolates of A. actinomycetemcomitans represented by self-aggregating, biofilm-associated and isogenic planktonic variants. Data obtained showed that complement-mediated phagocytosis of A. actinomycetemcomitans was generally inefficient regardless of strain-specific serotype or leukotoxin production. Furthermore, the majority of ingested bacteria remained viable after exposure to neutrophils for 1 h. Interestingly, uptake of antibody-opsonized bacteria resulted in the rapid cell death of neutrophils. This was in contrast to ingestion of complement-opsonized bacteria, which did not affect neutrophil viability. The methods used in this study provided reliable and reproducible results with respect to adherence, phagocytosis and killing of A. actinomycetemcomitans when encountering human neutrophils.

  2. Characterization of the hemocytes in Larvae of Protaetia brevitarsis seulensis: involvement of granulocyte-mediated phagocytosis.

    Directory of Open Access Journals (Sweden)

    Hyojung Kwon

    Full Text Available Hemocytes are key players in the immune response against pathogens in insects. However, the hemocyte types and their functions in the white-spotted flower chafers, Protaetia brevitarsis seulensis (Kolbe, are not known. In this study, we used various microscopes, molecular probes, and flow cytometric analyses to characterize the hemocytes in P. brevitarsis seulensis. The circulating hemocytes were classified based on their size, morphology, and dye-staining properties into six types, including granulocytes, plasmatocytes, oenocytoids, spherulocytes, prohemocytes, and adipohemocytes. The percentages of circulating hemocyte types were as follows: 13% granulocytes, 20% plasmatocytes, 1% oenocytoids, 5% spherulocytes, 17% prohemocytes, and 44% adipohemocytes. Next, we identified the professional phagocytes, granulocytes, which mediate encapsulation and phagocytosis of pathogens. The granulocytes were immunologically or morphologically activated and phagocytosed potentially hazardous substances in vivo. In addition, we showed that the phagocytosis by granulocytes is associated with autophagy, and that the activation of autophagy could be an efficient way to eliminate pathogens in this system. We also observed a high accumulation of autophagic vacuoles in activated granulocytes, which altered their shape and led to autophagic cell death. Finally, the granulocytes underwent mitotic division thus maintaining their number in vivo.

  3. Characterization of the hemocytes in Larvae of Protaetia brevitarsis seulensis: involvement of granulocyte-mediated phagocytosis.

    Science.gov (United States)

    Kwon, Hyojung; Bang, Kyeongrin; Cho, Saeyoull

    2014-01-01

    Hemocytes are key players in the immune response against pathogens in insects. However, the hemocyte types and their functions in the white-spotted flower chafers, Protaetia brevitarsis seulensis (Kolbe), are not known. In this study, we used various microscopes, molecular probes, and flow cytometric analyses to characterize the hemocytes in P. brevitarsis seulensis. The circulating hemocytes were classified based on their size, morphology, and dye-staining properties into six types, including granulocytes, plasmatocytes, oenocytoids, spherulocytes, prohemocytes, and adipohemocytes. The percentages of circulating hemocyte types were as follows: 13% granulocytes, 20% plasmatocytes, 1% oenocytoids, 5% spherulocytes, 17% prohemocytes, and 44% adipohemocytes. Next, we identified the professional phagocytes, granulocytes, which mediate encapsulation and phagocytosis of pathogens. The granulocytes were immunologically or morphologically activated and phagocytosed potentially hazardous substances in vivo. In addition, we showed that the phagocytosis by granulocytes is associated with autophagy, and that the activation of autophagy could be an efficient way to eliminate pathogens in this system. We also observed a high accumulation of autophagic vacuoles in activated granulocytes, which altered their shape and led to autophagic cell death. Finally, the granulocytes underwent mitotic division thus maintaining their number in vivo.

  4. Blocking the expression of syntaxin 4 interferes with initial phagocytosis of Brucella melitensis in macrophages.

    Science.gov (United States)

    Castañeda-Ramírez, Alfredo; González-Rodríguez, Diana; Hernández-Pineda, J Aide; Verdugo-Rodríguez, Antonio

    2015-01-01

    Brucella melitensis is the Brucella species most frequently associated with brucellosis in humans. It is also the causative agent of the disease in goats and other ruminants. Although significant aspects of the pathogenesis of infection by this intracellular pathogen have been clarified, several events during invasion of host cells remain to be elucidated. In this study, infections of human macrophages from the THP-1 monocyte cell line were conducted with B. melitensis Bm133 wild-type strain and a strain of Salmonella serovar Enteritidis as a control. A multiplicity of infection of 100 was used in trials focused on defining the relative expression of syntaxin 4 (STX4), a soluble N-ethylmaleimide-sensitive factor attachment protein receptor, in the early events of phagocytosis (at 15, 30, 45, and 60 min). Immunoblot assays were also done to visualize expression of the protein in cells infected with either bacterial strain. The expression of STX4 was not significantly different in cells infected with B. melitensis strain Bm133 compared to that observed in cells infected with S. Enteritidis. When the expression of STX4 mRNA was inhibited with short or small interfering, or silencing, RNA in the THP-1 cells, the survival of B. melitensis was significantly reduced at time 0, when gentamicin treatment of cultures was begun (after 1 h of phagocytosis), and also at 2 h and 12 h after infection.

  5. Pseudomonas aeruginosa eliminates natural killer cells via phagocytosis-induced apoptosis.

    Directory of Open Access Journals (Sweden)

    Jin Woong Chung

    2009-08-01

    Full Text Available Pseudomonas aeruginosa (PA is an opportunistic pathogen that causes the relapse of illness in immunocompromised patients, leading to prolonged hospitalization, increased medical expense, and death. In this report, we show that PA invades natural killer (NK cells and induces phagocytosis-induced cell death (PICD of lymphocytes. In vivo tumor metastasis was augmented by PA infection, with a significant reduction in NK cell number. Adoptive transfer of NK cells mitigated PA-induced metastasis. Internalization of PA into NK cells was observed by transmission electron microscopy. In addition, PA invaded NK cells via phosphoinositide 3-kinase (PI3K activation, and the phagocytic event led to caspase 9-dependent apoptosis of NK cells. PA-mediated NK cell apoptosis was dependent on activation of mitogen-activated protein (MAP kinase and the generation of reactive oxygen species (ROS. These data suggest that the phagocytosis of PA by NK cells is a critical event that affects the relapse of diseases in immunocompromised patients, such as those with cancer, and provides important insights into the interactions between PA and NK cells.

  6. Macrophage phagocytosis alters the MRI signal of ferumoxytol-labeled mesenchymal stromal cells in cartilage defects

    Science.gov (United States)

    Nejadnik, Hossein; Lenkov, Olga; Gassert, Florian; Fretwell, Deborah; Lam, Isaac; Daldrup-Link, Heike E.

    2016-05-01

    Human mesenchymal stem cells (hMSCs) are a promising tool for cartilage regeneration in arthritic joints. hMSC labeling with iron oxide nanoparticles enables non-invasive in vivo monitoring of transplanted cells in cartilage defects with MR imaging. Since graft failure leads to macrophage phagocytosis of apoptotic cells, we evaluated in vitro and in vivo whether nanoparticle-labeled hMSCs show distinct MR signal characteristics before and after phagocytosis by macrophages. We found that apoptotic nanoparticle-labeled hMSCs were phagocytosed by macrophages while viable nanoparticle-labeled hMSCs were not. Serial MRI scans of hMSC transplants in arthritic joints of recipient rats showed that the iron signal of apoptotic, nanoparticle-labeled hMSCs engulfed by macrophages disappeared faster compared to viable hMSCs. This corresponded to poor cartilage repair outcomes of the apoptotic hMSC transplants. Therefore, rapid decline of iron MRI signal at the transplant site can indicate cell death and predict incomplete defect repair weeks later. Currently, hMSC graft failure can be only diagnosed by lack of cartilage defect repair several months after cell transplantation. The described imaging signs can diagnose hMSC transplant failure more readily, which could enable timely re-interventions and avoid unnecessary follow up studies of lost transplants.

  7. Antimicrobial stewardship: Limits for implementation

    NARCIS (Netherlands)

    Sinha, Bhanu

    2014-01-01

    Antibiotic stewardship programme (ASP) is a multifaceted approach to improve patients' clinical outcomes, prevent the emergence of antimicrobial resistance, and reduce hospital costs by prudent and focused antimicrobial use. Development of local treatment guidelines according to local ecology, rapid

  8. General principles of antimicrobial therapy.

    Science.gov (United States)

    Leekha, Surbhi; Terrell, Christine L; Edson, Randall S

    2011-02-01

    Antimicrobial agents are some of the most widely, and often injudiciously, used therapeutic drugs worldwide. Important considerations when prescribing antimicrobial therapy include obtaining an accurate diagnosis of infection; understanding the difference between empiric and definitive therapy; identifying opportunities to switch to narrow-spectrum, cost-effective oral agents for the shortest duration necessary; understanding drug characteristics that are peculiar to antimicrobial agents (such as pharmacodynamics and efficacy at the site of infection); accounting for host characteristics that influence antimicrobial activity; and in turn, recognizing the adverse effects of antimicrobial agents on the host. It is also important to understand the importance of antimicrobial stewardship, to know when to consult infectious disease specialists for guidance, and to be able to identify situations when antimicrobial therapy is not needed. By following these general principles, all practicing physicians should be able to use antimicrobial agents in a responsible manner that benefits both the individual patient and the community.

  9. Antimicrobial Peptides (AMPs

    Directory of Open Access Journals (Sweden)

    Mehrzad Sadredinamin

    2016-04-01

    Full Text Available Antimicrobial peptides (AMPs are extensive group of molecules that produced by variety tissues of invertebrate, plants, and animal species which play an important role in their immunity response. AMPs have different classifications such as; biosynthetic machines, biological sources, biological functions, molecular properties, covalent bonding patterns, three dimensional structures, and molecular targets.These molecules have multidimensional properties including antimicrobial activity, antiviral activity, antifungal activity, anti-parasite activity, biofilm control, antitumor activity, mitogens activity and linking innate to adaptive immunity that making them promising agents for therapeutic drugs. In spite of this advantage of AMPs, their clinical developments have some limitation for commercial development. But some of AMPs are under clinical trials for the therapeutic purpose such as diabetic foot ulcers, different bacterial infections and tissue damage. In this review, we emphasized on the source, structure, multidimensional properties, limitation and therapeutic applications of various antimicrobial peptides.

  10. EGF Receptor-Dependent Mechanism May be Involved in the Tamm–Horsfall Glycoprotein-Enhanced PMN Phagocytosis via Activating Rho Family and MAPK Signaling Pathway

    Directory of Open Access Journals (Sweden)

    Ko-Jen Li

    2014-01-01

    Full Text Available Our previous studies showed that urinary Tamm–Horsfall glycoprotein (THP potently enhanced polymorphonuclear neutrophil (PMN phagocytosis. However, the domain structure(s, signaling pathway and the intracellular events responsible for THP-enhanced PMN phagocytosis remain to be elucidated. THP was purified from normal human urine. The human promyelocytic leukemia cell line HL-60 was induced to differentiate into PMNs by all-trans retinoid acid. Pretreatment with different MAPK and PI3K inhibitors was used to delineate signaling pathways in THP-enhanced PMN phagocytosis. Phosphorylation of molecules responsible for PMN phagocytosis induced by bacterial lipopolysaccharide (LPS, THP, or human recombinant epidermal growth factor (EGF was evaluated by western blot. A p38 MAPK inhibitor, SB203580, effectively inhibited both spontaneous and LPS- and THP-induced PMN phagocytosis. Both THP and LPS enhanced the expression of the Rho family proteins Cdc42 and Rac that may lead to F-actin re-arrangement. Further studies suggested that THP and EGF enhance PMN and differentiated HL-60 cell phagocytosis in a similar pattern. Furthermore, the EGF receptor inhibitor GW2974 significantly suppressed THP- and EGF-enhanced PMN phagocytosis and p38 and ERK1/2 phosphorylation in differentiated HL-60 cells. We conclude that EGF receptor-dependent signaling may be involved in THP-enhanced PMN phagocytosis by activating Rho family and MAP kinase.

  11. Descriptors for antimicrobial peptides

    DEFF Research Database (Denmark)

    Jenssen, Håvard

    2011-01-01

    Introduction: A frightening increase in the number of isolated multidrug resistant bacterial strains linked to the decline in novel antimicrobial drugs entering the market is a great cause for concern. Cationic antimicrobial peptides (AMPs) have lately been introduced as a potential new class...... examples of different peptide QSAR studies, this review highlights some of the missing links and illuminates some of the questions that would be interesting to challenge in a more systematic fashion. Expert opinion: Computer-aided peptide QSAR using molecular descriptors may provide the necessary edge...

  12. Antimicrobial resistance challenged with metal-based antimicrobial macromolecules.

    Science.gov (United States)

    Abd-El-Aziz, Alaa S; Agatemor, Christian; Etkin, Nola

    2017-02-01

    Antimicrobial resistance threatens the achievements of science and medicine, as it deactivates conventional antimicrobial therapeutics. Scientists respond to the threat by developing new antimicrobial platforms to prevent and treat infections from these resistant strains. Metal-based antimicrobial macromolecules are emerging as an alternative to conventional platforms because they combine multiple mechanisms of action into one platform due to the distinctive properties of metals. For example, metals interact with intracellular proteins and enzymes, and catalyse various intracellular processes. The macromolecular architecture offers a means to enhance antimicrobial activity since several antimicrobial moieties can be conjugated to the scaffold. Further, these macromolecules can be fabricated into antimicrobial materials for contact-killing medical implants, fabrics, and devices. As volatilization or leaching out of the antimicrobial moieties from the macromolecular scaffold is reduced, these medical implants, fabrics, and devices can retain their antimicrobial activity over an extended period. Recent advances demonstrate the potential of metal-based antimicrobial macromolecules as effective platforms that prevent and treat infections from resistant strains. In this review these advances are thoroughly discussed within the context of examples of metal-based antimicrobial macromolecules, their mechanisms of action and biocompatibility. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. 动物源产气荚膜梭菌耐药性的研究进展%Research progress on antimicrobial resistance in Clostridium perfringens of animal origin

    Institute of Scientific and Technical Information of China (English)

    董卫超; 刘凌; 杜向党

    2012-01-01

    Clostridium perfringens is an important zoonotic pathogen that can cause; various diseases in animals and hu -mans . The antimicrobial resistance in Clostridium perfringens is common in animal production . M ost of the resistant genes in Clostridium perfringens locate on the conjngative plasm ids or mobile genetic elements , which accelerate its dissemination . In this article , the resistance mechanism of Clostridium perfringens to the commonly used antimicrobials including tetracyclines , macrolides , lincosamides , streptogramins , cloramphenicol and bacitracin was summarized . In addition , the role the conjngative plasmids or the mobilized transposons played in the horizontal dissemination of the resistant genes in Clostridium perfringens was clarified . The deep understanding on the resistance mechanism of Clostridium perfringens of animal origin can aid the control of this pathogen , which provides the guarantee for the food safety and human health .%目的 产气荚膜梭菌是可引起多种动物和人类疾病的重要人兽共患病原菌.其抗生素耐药性在动物生产中较为普遍,多数耐药基因常位于接合型质粒或流动遗传因子上,加速了产气荚膜梭菌耐药性的扩散.本文概述了动物源产气荚膜梭菌对常用抗生素(四环素类、大环内酯类、林可胺类、链阳霉素类以及氯霉素和杆菌肽锌等)的耐药机制.在此基础上,阐述了接合型质粒和转座子等在产气荚膜梭菌耐药基因水平扩散中的作用.对动物源产气荚膜梭菌耐药机制及扩散机理的深入认识有助于该菌的控制,为食品安全和人类健康提供重要保障.

  14. Animation of Antimicrobial Resistance

    Medline Plus

    Full Text Available ... En Español Search FDA Submit search Popular Content Home Food Drugs Medical Devices Radiation-Emitting Products Vaccines, ... Biologics Animal & Veterinary Cosmetics Tobacco Products Animal & Veterinary Home Animal & Veterinary Safety & Health Antimicrobial Resistance Animation of ...

  15. Antimicrobial Prophylaxis in Adults

    OpenAIRE

    Enzler, Mark J.; Berbari, Elie; Osmon, Douglas R.

    2011-01-01

    Antimicrobial prophylaxis is commonly used by clinicians for the prevention of numerous infectious diseases, including herpes simplex infection, rheumatic fever, recurrent cellulitis, meningococcal disease, recurrent uncomplicated urinary tract infections in women, spontaneous bacterial peritonitis in patients with cirrhosis, influenza, infective endocarditis, pertussis, and acute necrotizing pancreatitis, as well as infections associated with open fractures, recent prosthetic joint placement...

  16. Animation of Antimicrobial Resistance

    Medline Plus

    Full Text Available ... use of antimicrobial drugs will result in the development of resistant strains of bacteria, complicating clinician's efforts ... Português | Italiano | Deutsch | 日本語 | فارسی | English FDA Accessibility Careers FDA Basics FOIA No FEAR Act Site Map ...

  17. Effects of early-life lead exposure on oxidative status and phagocytosis activity in great tits (Parus major)

    NARCIS (Netherlands)

    Rainio, Miia J.; Eeva, Tapio; Lilley, Thomas; Stauffer, Janina; Ruuskanen, Suvi

    2015-01-01

    Abstract Lead is a highly poisonous metal with a very long half-life, distributing throughout the body in blood and accumulating primarily in bones and kidney. We studied the short and long-term effects of early-life lead exposure on antioxidant defense and phagocytosis activity in a small passerine

  18. Interaction between Salmonella typhimurium and phagocytic cells in pigs - Phagocytosis, oxidative burst and killing in polymorphonuclear leukocytes and monocytes

    DEFF Research Database (Denmark)

    Riber, Ulla; Lind, Peter

    1999-01-01

    Interactions between Salmonella typhimurium and peripheral blood leucocytes from healthy, Salmonella-free pigs were investigated in vitro. Both granulocytes and monocytes phagocytized FITC-labelled heat-killed Salmonella bacteria as shown by flow cytometry. Phagocytosis in whole blood and isolated...

  19. Protein C inhibitor (PCI) binds to phosphatidylserine exposing cells with implications in the phagocytosis of apoptotic cells and activated platelets.

    Science.gov (United States)

    Rieger, Daniela; Assinger, Alice; Einfinger, Katrin; Sokolikova, Barbora; Geiger, Margarethe

    2014-01-01

    Protein C Inhibitor (PCI) is a secreted serine protease inhibitor, belonging to the family of serpins. In addition to activated protein C PCI inactivates several other proteases of the coagulation and fibrinolytic systems, suggesting a regulatory role in hemostasis. Glycosaminoglycans and certain negatively charged phospholipids, like phosphatidylserine, bind to PCI and modulate its activity. Phosphatidylerine (PS) is exposed on the surface of apoptotic cells and known as a phagocytosis marker. We hypothesized that PCI might bind to PS exposed on apoptotic cells and thereby influence their removal by phagocytosis. Using Jurkat T-lymphocytes and U937 myeloid cells, we show here that PCI binds to apoptotic cells to a similar extent at the same sites as Annexin V, but in a different manner as compared to live cells (defined spots on ∼10-30% of cells). PCI dose dependently decreased phagocytosis of apoptotic Jurkat cells by U937 macrophages. Moreover, the phagocytosis of PS exposing, activated platelets by human blood derived monocytes declined in the presence of PCI. In U937 cells the expression of PCI as well as the surface binding of PCI increased with time of phorbol ester treatment/macrophage differentiation. The results of this study suggest a role of PCI not only for the function and/or maturation of macrophages, but also as a negative regulator of apoptotic cell and activated platelets removal.

  20. Phagocytosis escape by a Staphylococcus aureus protein that connects complement and coagulation proteins at the bacterial surface.

    Science.gov (United States)

    Ko, Ya-Ping; Kuipers, Annemarie; Freitag, Claudia M; Jongerius, Ilse; Medina, Eva; van Rooijen, Willemien J; Spaan, András N; van Kessel, Kok P M; Höök, Magnus; Rooijakkers, Suzan H M

    2013-01-01

    Upon contact with human plasma, bacteria are rapidly recognized by the complement system that labels their surface for uptake and clearance by phagocytic cells. Staphylococcus aureus secretes the 16 kD Extracellular fibrinogen binding protein (Efb) that binds two different plasma proteins using separate domains: the Efb N-terminus binds to fibrinogen, while the C-terminus binds complement C3. In this study, we show that Efb blocks phagocytosis of S. aureus by human neutrophils. In vitro, we demonstrate that Efb blocks phagocytosis in plasma and in human whole blood. Using a mouse peritonitis model we show that Efb effectively blocks phagocytosis in vivo, either as a purified protein or when produced endogenously by S. aureus. Mutational analysis revealed that Efb requires both its fibrinogen and complement binding residues for phagocytic escape. Using confocal and transmission electron microscopy we show that Efb attracts fibrinogen to the surface of complement-labeled S. aureus generating a 'capsule'-like shield. This thick layer of fibrinogen shields both surface-bound C3b and antibodies from recognition by phagocytic receptors. This information is critical for future vaccination attempts, since opsonizing antibodies may not function in the presence of Efb. Altogether we discover that Efb from S. aureus uniquely escapes phagocytosis by forming a bridge between a complement and coagulation protein.

  1. Protein C inhibitor (PCI binds to phosphatidylserine exposing cells with implications in the phagocytosis of apoptotic cells and activated platelets.

    Directory of Open Access Journals (Sweden)

    Daniela Rieger

    Full Text Available Protein C Inhibitor (PCI is a secreted serine protease inhibitor, belonging to the family of serpins. In addition to activated protein C PCI inactivates several other proteases of the coagulation and fibrinolytic systems, suggesting a regulatory role in hemostasis. Glycosaminoglycans and certain negatively charged phospholipids, like phosphatidylserine, bind to PCI and modulate its activity. Phosphatidylerine (PS is exposed on the surface of apoptotic cells and known as a phagocytosis marker. We hypothesized that PCI might bind to PS exposed on apoptotic cells and thereby influence their removal by phagocytosis. Using Jurkat T-lymphocytes and U937 myeloid cells, we show here that PCI binds to apoptotic cells to a similar extent at the same sites as Annexin V, but in a different manner as compared to live cells (defined spots on ∼10-30% of cells. PCI dose dependently decreased phagocytosis of apoptotic Jurkat cells by U937 macrophages. Moreover, the phagocytosis of PS exposing, activated platelets by human blood derived monocytes declined in the presence of PCI. In U937 cells the expression of PCI as well as the surface binding of PCI increased with time of phorbol ester treatment/macrophage differentiation. The results of this study suggest a role of PCI not only for the function and/or maturation of macrophages, but also as a negative regulator of apoptotic cell and activated platelets removal.

  2. Identification of intracellular phospholipases A2 in the human eye: involvement in phagocytosis of photoreceptor outer segments

    DEFF Research Database (Denmark)

    Kolko, Miriam; Wang, Jinmei; Zhan, Chen

    2007-01-01

    PURPOSE: To identify intracellular phospholipases A(2) (PLA(2)) in the human retina and to explore the role of these enzymes in human retinal pigment epithelium (RPE) phagocytosis of photoreceptor outer segments (POS). METHODS: PCR amplification and Western blot analysis were used to identify mRN...

  3. Cryptococcus neoformans Is Internalized by Receptor-Mediated or ‘Triggered’ Phagocytosis, Dependent on Actin Recruitment

    Science.gov (United States)

    Guerra, Caroline Rezende; Seabra, Sergio Henrique; de Souza, Wanderley; Rozental, Sonia

    2014-01-01

    Cryptococcosis by the encapsulated yeast Cryptococcus neoformans affects mostly immunocompromised individuals and is a frequent neurological complication in AIDS patients. Recent studies support the idea that intracellular survival of Cryptococcus yeast cells is important for the pathogenesis of cryptococcosis. However, the initial steps of Cryptococcus internalization by host cells remain poorly understood. Here, we investigate the mechanism of Cryptococcus neoformans phagocytosis by peritoneal macrophages using confocal and electron microscopy techniques, as well as flow cytometry quantification, evaluating the importance of fungal capsule production and of host cell cytoskeletal elements for fungal phagocytosis. Electron microscopy analyses revealed that capsular and acapsular strains of C. neoformans are internalized by macrophages via both ‘zipper’ (receptor-mediated) and ‘trigger’ (membrane ruffle-dependent) phagocytosis mechanisms. Actin filaments surrounded phagosomes of capsular and acapsular yeasts, and the actin depolymerizing drugs cytochalasin D and latrunculin B inhibited yeast internalization and actin recruitment to the phagosome area. In contrast, nocodazole and paclitaxel, inhibitors of microtubule dynamics decreased internalization but did not prevent actin recruitment to the site of phagocytosis. Our results show that different uptake mechanisms, dependent on both actin and tubulin dynamics occur during yeast internalization by macrophages, and that capsule production does not affect the mode of Cryptococcus uptake by host cells. PMID:24586631

  4. Effects of early-life lead exposure on oxidative status and phagocytosis activity in great tits (Parus major)

    NARCIS (Netherlands)

    Rainio, Miia J.; Eeva, Tapio; Lilley, Thomas; Stauffer, Janina; Ruuskanen, Suvi

    2015-01-01

    Abstract Lead is a highly poisonous metal with a very long half-life, distributing throughout the body in blood and accumulating primarily in bones and kidney. We studied the short and long-term effects of early-life lead exposure on antioxidant defense and phagocytosis activity in a small passerine

  5. Glycoengineered CD20 antibody obinutuzumab activates neutrophils and mediates phagocytosis through CD16B more efficiently than rituximab.

    Science.gov (United States)

    Golay, Josée; Da Roit, Fabio; Bologna, Luca; Ferrara, Claudia; Leusen, Jeanette H; Rambaldi, Alessandro; Klein, Christian; Introna, Martino

    2013-11-14

    Obinutuzumab (GA101) is a glycoengineered type 2 CD20 antibody with enhanced CD16A-binding and natural killer-mediated cytotoxicity. CD16B is highly homologous to CD16A and a major FcγR on human polymorphonuclear neutrophils (PMNs). We show here that glycoengineered obinutuzumab or rituximab bound CD16B with approximately sevenfold higher affinity, compared with nonglycoengineered wild-type parental antibodies. Furthermore, glycoengineered obinutuzumab activated PMNs, either purified or in chronic lymphoblastic leukemia whole blood, more efficiently than wild-type rituximab. Activation resulted in a 50% increase in CD11b expression and 70% down-modulation of CD62L on neutrophils and in release of tumor necrosis factor alpha, IL-6, and IL-8. Activation was not accompanied by generation of reactive oxygen species or antibody-dependent cellular cytotoxicity activity, but led to up to 47% phagocytosis of glycoengineered anti-CD20 opsonized chronic lymphoblastic leukemia targets by purified PMNs. Significant phagocytosis was observed in whole blood, but only in the presence of glycoengineered antibodies, and was followed by up to 50% PMN death. Finally we show, using anti-CD16B and anti-CD32A Fab and F(ab')2 fragments, that both of these receptors are involved in PMN activation, phagocytosis, and cell death induced by glycoengineered antibodies. We conclude that phagocytosis by PMNs is an additional mechanism of action of obinutuzumab mediated through its higher binding affinity for CD16B.

  6. Bruton's Tyrosine Kinase (BTK) and Vav1 Contribute to Dectin1-Dependent Phagocytosis of Candida albicans in Macrophages

    NARCIS (Netherlands)

    Strijbis, Karin; Tafesse, Fikadu G.; Fairn, Gregory D.; Witte, Martin D.; Dougan, Stephanie K.; Watson, Nicki; Spooner, Eric; Esteban, Alexandre; Vyas, Valmik K.; Fink, Gerald R.; Grinstein, Sergio; Ploegh, Hidde L.

    Phagocytosis of the opportunistic fungal pathogen Candida albicans by cells of the innate immune system is vital to prevent infection. Dectin-1 is the major phagocytic receptor involved in anti-fungal immunity. We identify two new interacting proteins of Dectin-1 in macrophages, Bruton's Tyrosine

  7. EFFECT OF INHALED ENDOTOXIN ON AIRWAY AND CIRCULATING INFLAMMATORY CELL PHAGOCYTOSIS AND CD11B EXPRESSION IN ATOPIC ASTHMATIC SUBJECTS

    Science.gov (United States)

    Effect of inhaled endotoxin on airway and circulating inflammatory cell phagocytosis and CD11b expression in atopic asthmatic subjects Neil E. Alexis, PhD, Marlowe W. Eldridge, MD, David B. Peden, MD, MS Chapel Hill and Research Triangle Park, NCBackgrou...

  8. Triclosan antimicrobial polymers

    Directory of Open Access Journals (Sweden)

    Richard C. Petersen

    2016-03-01

    Full Text Available Triclosan antimicrobial molecular fluctuating energies of nonbonding electron pairs for the oxygen atom by ether bond rotations are reviewed with conformational computational chemistry analyses. Subsequent understanding of triclosan alternating ether bond rotations is able to help explain several material properties in Polymer Science. Unique bond rotation entanglements between triclosan and the polymer chains increase both the mechanical properties of polymer toughness and strength that are enhanced even better through secondary bonding relationships. Further, polymer blend compatibilization is considered due to similar molecular relationships and polarities. With compatibilization of triclosan in polymers a more uniform stability for nonpolar triclosan in the polymer solid state is retained by the antimicrobial for extremely low release with minimum solubility into aqueous solution. As a result, triclosan is projected for long extended lifetimes as an antimicrobial polymer additive. Further, triclosan rapid alternating ether bond rotations disrupt secondary bonding between chain monomers in the resin state to reduce viscosity and enhance polymer blending. Thus, triclosan is considered for a polymer additive with multiple properties to be an antimicrobial with additional benefits as a nonpolar toughening agent and a hydrophobic wetting agent. The triclosan material relationships with alternating ether bond rotations are described through a complete different form of medium by comparisons with known antimicrobial properties that upset bacterial cell membranes through rapid fluctuating mechanomolecular energies. Also, triclosan bond entanglements with secondary bonding can produce structural defects in weak bacterial lipid membranes requiring pliability that can then interfere with cell division. Regarding applications with polymers, triclosan can be incorporated by mixing into a resin system before cure, melt mixed with thermoplastic polymers

  9. Triclosan antimicrobial polymers

    Science.gov (United States)

    Petersen, Richard C.

    2016-01-01

    Triclosan antimicrobial molecular fluctuating energies of nonbonding electron pairs for the oxygen atom by ether bond rotations are reviewed with conformational computational chemistry analyses. Subsequent understanding of triclosan alternating ether bond rotations is able to help explain several material properties in Polymer Science. Unique bond rotation entanglements between triclosan and the polymer chains increase both the mechanical properties of polymer toughness and strength that are enhanced even better through secondary bonding relationships. Further, polymer blend compatibilization is considered due to similar molecular relationships and polarities. With compatibilization of triclosan in polymers a more uniform stability for nonpolar triclosan in the polymer solid state is retained by the antimicrobial for extremely low release with minimum solubility into aqueous solution. As a result, triclosan is projected for long extended lifetimes as an antimicrobial polymer additive. Further, triclosan rapid alternating ether bond rotations disrupt secondary bonding between chain monomers in the resin state to reduce viscosity and enhance polymer blending. Thus, triclosan is considered for a polymer additive with multiple properties to be an antimicrobial with additional benefits as a nonpolar toughening agent and a hydrophobic wetting agent. The triclosan material relationships with alternating ether bond rotations are described through a complete different form of medium by comparisons with known antimicrobial properties that upset bacterial cell membranes through rapid fluctuating mechanomolecular energies. Also, triclosan bond entanglements with secondary bonding can produce structural defects in weak bacterial lipid membranes requiring pliability that can then interfere with cell division. Regarding applications with polymers, triclosan can be incorporated by mixing into a resin system before cure, melt mixed with thermoplastic polymers that set on cooling

  10. Differential clearance mechanisms, neutrophil extracellular trap degradation and phagocytosis, are operative in systemic lupus erythematosus patients with distinct autoantibody specificities.

    Science.gov (United States)

    Chauhan, Sudhir Kumar; Rai, Richa; Singh, Vikas Vikram; Rai, Madhukar; Rai, Geeta

    2015-12-01

    Systemic lupus erythematosus (SLE) patients are generally presented with autoantibodies against either dsDNA or RNA-associated antigens (also known as extractable nuclear antigens, ENA) or both. However, the mechanisms and processes that lead to this distinctive autoantibody profile are not well understood. Defects in clearance mechanism i.e. phagocytosis may lead to enhanced microbial and cellular debris of immunogenic potential. In addition to defective phagocytosis, impaired neutrophil extracellular trap (NET) degradation has been recently reported in SLE patients. However, the extent to which both these clearance processes (NET-degradation and phagocytosis) are operative in serologically distinguished subsets of SLE patients is not established. Therefore, in this report, we evaluated NET-degradation and phagocytosis efficiency among SLE patients with different autoantibody specificities. SLE patients were classified into three subsets based on their autoantibody profile (anti-dsDNA, anti-ENA or both) as determined by ELISA. NET-degradation by SLE and control sera was assessed by sytox orange-based fluorescence assay. Neutrophil-mediated phagocytosis in the presence of SLE and control sera was determined by flowcytometry. The segregation of SLE patients revealed significant differences in NET-degradation and phagocytosis in SLE patients with autoantibodies against dsDNA and ENA. We report that NET-degradation efficiency was significantly impaired in SLE patients with anti-dsDNA autoantibodies and not in those with anti-ENA autoantibodies. In contrast to NET-degradation, neutrophil-mediated phagocytosis was impaired in all three subsets independent of autoantibody specificity. These observations suggest that varying clearance mechanisms are operative in SLE subsets with anti-dsDNA or anti-ENA autoantibodies. The results outlined in this manuscript also suggest that sub-grouping of SLE patients could be useful in delineating the molecular and pathological

  11. Structural and functional changes in pulmonary macrophages during phagocytosis caused by natural zeolite-clinoptilolite

    Energy Technology Data Exchange (ETDEWEB)

    Kruglikov, G.G.; Velichkovskii, B.T.; Garmash, T.I.; Volkogonova, V.M. (Rossiiskii Gosudarstvennyi Meditsinskii Universitet, Moscow (Russian Federation))

    1992-11-01

    Invstigates cytotoxic properties of clinoptilolite and structural and functional state of pulmonary macrophages in the course of phagocytosis caused by exposure to clinoptilolite. Investigations were carried out on white rats with quartz dust and dust of black coal from the Kemerovo coal deposit used in two reference groups. Toxic dust was administered intratracheally in saline solution, coal dust in a 1% starch solution. Pathological processes in phagocytic cells observed using electron microscopy are described. More pronounced cytotoxic effects of clinoptilolite in comparison with those of coal dust are pointed out. The following pathological phenomena in cells were observed: vigorous phagocytic processes on clinoptilolite particles; active lysosome reaction and lipid accumulation; irreversible changes in mitochondrea; development of destructive types of macrophages. 5 refs.

  12. Phagocytosis-inspired behaviour in synthetic protocell communities of compartmentalized colloidal objects

    Science.gov (United States)

    Rodríguez-Arco, Laura; Li, Mei; Mann, Stephen

    2017-08-01

    The spontaneous assembly of micro-compartmentalized colloidal objects capable of controlled interactions offers a step towards rudimentary forms of collective behaviour in communities of artificial cell-like entities (synthetic protocells). Here we report a primitive form of artificial phagocytosis in a binary community of synthetic protocells in which multiple silica colloidosomes are selectively ingested by self-propelled magnetic Pickering emulsion (MPE) droplets comprising particle-free fatty acid-stabilized apertures. Engulfment of the colloidosomes enables selective delivery and release of water-soluble payloads, and can be coupled to enzyme activity within the MPE droplets. Our results highlight opportunities for the development of new materials based on consortia of colloidal objects, and provide a novel microscale engineering approach to inducing higher-order behaviour in mixed populations of synthetic protocells.

  13. Determination of phagocytosis of /sup 32/P-labeled Staphylococcus aureus by bovine polymorphonuclear leukocytes

    Energy Technology Data Exchange (ETDEWEB)

    Dulin, A.M.; Paape, M.J.; Weinland, B.T.

    1984-04-01

    A procedure for the measurement of phagocytosis by bovine polymorphonuclear leukocytes (PMN) of /sup 32/P-labeled Staphylococcus aureus was modified so that a larger number of samples could be compared in a single run, and smaller volumes of sample, PMN, and /sup 32/P-labeled S aureus could be used. Results were highly reproducible, with a coefficient of variation between duplicate determinations of less than or equal to 2%. Lysostaphin was prepared from the supernatant of S staphylolyticus and was compared with a commercially available preparation. Effects of lysostaphin on PMN and influence of incubation media on release of /sup 32/P from /sup 32/P-labeled S aureus by lysostaphin were examined.

  14. Inhibition of phagocytosis by Haemophilus ducreyi requires expression of the LspA1 and LspA2 proteins.

    Science.gov (United States)

    Vakevainen, Merja; Greenberg, Steven; Hansen, Eric J

    2003-10-01

    Haemophilus ducreyi previously has been shown to inhibit the phagocytosis of both secondary targets and itself by certain cells in vitro. Wild-type H. ducreyi strain 35000HP contains two genes, lspA1 and lspA2, whose encoded protein products are predicted to be 456 and 543 kDa, respectively. An isogenic mutant of H. ducreyi 35000HP with inactivated lspA1 and lspA2 genes has been shown to exhibit substantially decreased virulence in the temperature-dependent rabbit model for chancroid. This lspA1 lspA2 mutant was tested for its ability to inhibit phagocytosis of immunoglobulin G-opsonized particles by differentiated HL-60 and U-937 cells and by J774A.1 cells. The wild-type strain H. ducreyi 35000HP readily inhibited phagocytosis, whereas the lspA1 lspA2 mutant was unable to inhibit phagocytosis. Similarly, the wild-type strain was resistant to phagocytosis, whereas the lspA1 lspA2 mutant was readily engulfed by phagocytes. This inhibitory effect of wild-type H. ducreyi on phagocytic activity was primarily associated with live bacterial cells but could also be found, under certain conditions, in concentrated H. ducreyi culture supernatant fluids that lacked detectable outer membrane fragments. Both the wild-type strain and the lspA1 lspA2 mutant attached to phagocytes at similar levels. These results indicate that the LspA1 and LspA2 proteins of H. ducreyi are involved, directly or indirectly, in the antiphagocytic activity of this pathogen, and they provide a possible explanation for the greatly reduced virulence of the lspA1 lspA2 mutant.

  15. Neuronal Hyperactivity Disturbs ATP Microgradients, Impairs Microglial Motility, and Reduces Phagocytic Receptor Expression Triggering Apoptosis/Microglial Phagocytosis Uncoupling.

    Directory of Open Access Journals (Sweden)

    Oihane Abiega

    2016-05-01

    Full Text Available Phagocytosis is essential to maintain tissue homeostasis in a large number of inflammatory and autoimmune diseases, but its role in the diseased brain is poorly explored. Recent findings suggest that in the adult hippocampal neurogenic niche, where the excess of newborn cells undergo apoptosis in physiological conditions, phagocytosis is efficiently executed by surveillant, ramified microglia. To test whether microglia are efficient phagocytes in the diseased brain as well, we confronted them with a series of apoptotic challenges and discovered a generalized response. When challenged with excitotoxicity in vitro (via the glutamate agonist NMDA or inflammation in vivo (via systemic administration of bacterial lipopolysaccharides or by omega 3 fatty acid deficient diets, microglia resorted to different strategies to boost their phagocytic efficiency and compensate for the increased number of apoptotic cells, thus maintaining phagocytosis and apoptosis tightly coupled. Unexpectedly, this coupling was chronically lost in a mouse model of mesial temporal lobe epilepsy (MTLE as well as in hippocampal tissue resected from individuals with MTLE, a major neurological disorder characterized by seizures, excitotoxicity, and inflammation. Importantly, the loss of phagocytosis/apoptosis coupling correlated with the expression of microglial proinflammatory, epileptogenic cytokines, suggesting its contribution to the pathophysiology of epilepsy. The phagocytic blockade resulted from reduced microglial surveillance and apoptotic cell recognition receptor expression and was not directly mediated by signaling through microglial glutamate receptors. Instead, it was related to the disruption of local ATP microgradients caused by the hyperactivity of the hippocampal network, at least in the acute phase of epilepsy. Finally, the uncoupling led to an accumulation of apoptotic newborn cells in the neurogenic niche that was due not to decreased survival but to delayed

  16. Rho is Required for the Initiation of Calcium Signaling and Phagocytosis by Fcγ Receptors in Macrophages

    Science.gov (United States)

    Hackam, David J.; Rotstein, Ori D.; Schreiber, Alan; Zhang, Wei-jian; Grinstein, Sergio

    1997-01-01

    Phagocytosis of bacteria by macrophages and neutrophils is an essential component of host defense against infection. The mechanism whereby the interaction of opsonized particles with Fcγ receptors triggers the engulfment of opsonized particles remains incompletely understood, although activation of tyrosine kinases has been recognized as an early step. Recent studies in other systems have demonstrated that tyrosine kinases can in turn signal the activation of small GTPases of the ras superfamily. We therefore investigated the possible role of Rho in Fc receptor–mediated phagocytosis. To this end we microinjected J774 macrophages with C3 exotoxin from Clostridium botulinum, which ADP-ribosylates and inactivates Rho. C3 exotoxin induced the retraction of filopodia, the disappearance of focal complexes, and a global decrease in the F-actin content of J774 cells. In addition, these cells exhibited increased spreading and the formation of vacuolar structures. Importantly, inactivation of Rho resulted in the complete abrogation of phagocytosis. Inhibition of Fcγ receptor–mediated phagocytosis by C3 exotoxin was confirmed in COS cells, which become phagocytic upon transfection of the FcγRIIA receptor. Rho was found to be essential for the accumulation of phosphotyrosine and of F-actin around phagocytic cups and for Fcγ receptor–mediated Ca2+ signaling. The clustering of receptors in response to opsonin, an essential step in Fcγ-induced signaling, was the earliest event shown to be inhibited by C3 exotoxin. The effect of the toxin was specific, since clustering and internalization of transferrin receptors were unaffected by microinjection of C3. These data identify a role for small GTPases in Fcγ receptor–mediated phagocytosis by leukocytes. PMID:9294149

  17. Household air pollution causes dose-dependent inflammation and altered phagocytosis in human macrophages.

    Science.gov (United States)

    Rylance, Jamie; Fullerton, Duncan G; Scriven, James; Aljurayyan, Abdullah N; Mzinza, David; Barrett, Steve; Wright, Adam K A; Wootton, Daniel G; Glennie, Sarah J; Baple, Katy; Knott, Amy; Mortimer, Kevin; Russell, David G; Heyderman, Robert S; Gordon, Stephen B

    2015-05-01

    Three billion people are exposed to household air pollution from biomass fuel use. Exposure is associated with higher incidence of pneumonia, and possibly tuberculosis. Understanding mechanisms underlying these defects would improve preventive strategies. We used human alveolar macrophages obtained from healthy Malawian adults exposed naturally to household air pollution and compared them with human monocyte-derived macrophages exposed in vitro to respirable-sized particulates. Cellular inflammatory response was assessed by IL-6 and IL-8 production in response to particulate challenge; phagosomal function was tested by uptake and oxidation of fluorescence-labeled beads; ingestion and killing of Streptococcus pneumoniae and Mycobacterium tuberculosis were measured by microscopy and quantitative culture. Particulate ingestion was quantified by digital image analysis. We were able to reproduce the carbon loading of naturally exposed alveolar macrophages by in vitro exposure of monocyte-derived macrophages. Fine carbon black induced IL-8 release from monocyte-derived and alveolar macrophages (P < 0.05) with similar magnitude responses (log10 increases of 0.93 [SEM = 0.2] versus 0.74 [SEM = 0.19], respectively). Phagocytosis of pneumococci and mycobacteria was impaired with higher particulate loading. High particulate loading corresponded with a lower oxidative burst capacity (P = 0.0015). There was no overall effect on killing of M. tuberculosis. Alveolar macrophage function is altered by particulate loading. Our macrophage model is comparable morphologically to the in vivo uptake of particulates. Wood smoke-exposed cells demonstrate reduced phagocytosis, but unaffected mycobacterial killing, suggesting defects related to chronic wood smoke inhalation limited to specific innate immune functions.

  18. Intravenous immunglobulin binds beta amyloid and modifies its aggregation, neurotoxicity and microglial phagocytosis in vitro.

    Directory of Open Access Journals (Sweden)

    Susann Cattepoel

    Full Text Available Intravenous Immunoglobulin (IVIG has been proposed as a potential therapeutic for Alzheimer's disease (AD and its efficacy is currently being tested in mild-to-moderate AD. Earlier studies reported the presence of anti-amyloid beta (Aβ antibodies in IVIG. These observations led to clinical studies investigating the potential role of IVIG as a therapeutic agent in AD. Also, IVIG is known to mediate beneficial effects in chronic inflammatory and autoimmune conditions by interfering with various pathological processes. Therefore, we investigated the effects of IVIG and purified polyclonal Aβ-specific antibodies (pAbs-Aβ on aggregation, toxicity and phagocytosis of Aβ in vitro, thus elucidating some of the potential mechanisms of action of IVIG in AD patients. We report that both IVIG and pAbs-Aβ specifically bound to Aβ and inhibited its aggregation in a dose-dependent manner as measured by Thioflavin T assay. Additionally, IVIG and the purified pAbs-Aβ inhibited Aβ-induced neurotoxicity in the SH-SY5Y human neuroblastoma cell line and prevented Aβ binding to rat primary cortical neurons. Interestingly, IVIG and pAbs-Aβ also increased the number of phagocytosing cells as well as the amount of phagocytosed fibrillar Aβ by BV-2 microglia. Phagocytosis of Aβ depended on receptor-mediated endocytosis and was accompanied by upregulation of CD11b expression. Importantly, we could also show that Privigen dose-dependently reversed Aβ-mediated LTP inhibition in mouse hippocampal slices. Therefore, our in vitro results suggest that IVIG may have an impact on different processes involved in AD pathogenesis, thereby promoting further understanding of the effects of IVIG observed in clinical studies.

  19. Research progress of storage of fresh-cut fruits and juices by natural antimicrobials%天然防腐剂在鲜切水果和果汁保鲜中的研究进展

    Institute of Scientific and Technical Information of China (English)

    王怡; 陆利霞; 熊晓辉

    2012-01-01

    With improved living standard , the demand for low - calorie foods are increasing. The consumption of ready - to - eat fresh - cut fruits and fruit juices is gradually increased because of the attention to the food safety. Due to damaged tissue and form, fresh -cut fruits and fruit juices are easy polluted caused by pathogenic and spoilage microorganisms. If treated under inappropriate manipulation arid storage conditions, the product may be subject to microhm! diseases and spoilage. Quality loss in fresh -cut fruits and unpasteurized juices may be caused by microbiological, en-isymatic, chemical, or physical changes. Among these, microbiological cause is particularly important; first, micro-bial toxins or pathogenic microorganisms in the product are harmfal to the health of consumers; second , mierobial spoilage may incur economic losses to consumers. The use of antiseptic can effectively reduce mierobial pollution and enhance safety. Natural food additives can assure safety and maintain quality characteristics. Studies on the use of natural substances to prevent fresh - cut fruits and unpasteurized juices from microbiological spoilage have been significantly increased in recent years. This review summaries the different studies on the antimicrobial effectiveness to pathogenic and spoilage microorganisms in fresh - cut fruits and fruit juices by natural antimicrobials of animal, plant and mierobial origin%随着国民生活水平的提高,人们对低热量食品的需求不断增大,即食鲜切水果和果汁的消费也逐渐增加,它们的安全性越来越受到人们的重视.鲜切水果和果汁由于组织和形态被破坏极易受到病原微生物和腐败微生物的污染,如果加工或储存条件不当,极易造成微生物致病和腐败.微生物学、酶学、化学或物理学变化均能引起鲜切水果与未高温消毒果汁的质量损失.其中,微生物造成的损失非常重要,有两方面原因:一是微生物毒素或病原微

  20. Bacterial antimicrobial metal ion resistance.

    Science.gov (United States)

    Hobman, Jon L; Crossman, Lisa C

    2015-05-01

    Metals such as mercury, arsenic, copper and silver have been used in various forms as antimicrobials for thousands of years with until recently, little understanding of their mode of action. The discovery of antibiotics and new organic antimicrobial compounds during the twentieth century saw a general decline in the clinical use of antimicrobial metal compounds, with the exception of the rediscovery of the use of silver for burns treatments and niche uses for other metal compounds. Antibiotics and new antimicrobials were regarded as being safer for the patient and more effective than the metal-based compounds they supplanted. Bacterial metal ion resistances were first discovered in the second half of the twentieth century. The detailed mechanisms of resistance have now been characterized in a wide range of bacteria. As the use of antimicrobial metals is limited, it is legitimate to ask: are antimicrobial metal resistances in pathogenic and commensal bacteria important now? This review details the new, rediscovered and 'never went away' uses of antimicrobial metals; examines the prevalence and linkage of antimicrobial metal resistance genes to other antimicrobial resistance genes; and examines the evidence for horizontal transfer of these genes between bacteria. Finally, we discuss the possible implications of the widespread dissemination of these resistances on re-emergent uses of antimicrobial metals and how this could impact upon the antibiotic resistance problem. © 2014 The Authors.

  1. Antimicrobial peptides in Echinoderms

    Directory of Open Access Journals (Sweden)

    C Li

    2010-05-01

    Full Text Available Antimicrobial peptides (AMPs are important immune effector molecules for invertebrates, including echinoderms, which lack a vertebrate-type adaptive immune system. Here we summarize the knowledge of such peptides in echinoderms. Strongylocins are a novel family of cysteine-rich AMPs, recently identified in the sea urchins, Strongylocentrotus droebachiensis and S. purpuratus. Although these molecules present diverse amino acid sequences, they share an identical cysteine arrangement pattern, dissimilar to other known AMPs. A family of heterodimeric AMPs, named centrocins, are also present in S. droebachiensis. Lysozymes and fragments of larger proteins, such as beta-thymocins, actin, histone 2A and filamin A have also been shown to display antimicrobial activities in echinoderms. Future studies on AMPs should be aimed in revealing how echinoderms use these AMPs in the immune response against microbial pathogens.

  2. Combating antimicrobial resistance: antimicrobial stewardship program in Taiwan.

    Science.gov (United States)

    Tseng, Shu-Hui; Lee, Chun-Ming; Lin, Tzou-Yien; Chang, Shan-Chwen; Chuang, Yin-Ching; Yen, Muh-Yong; Hwang, Kao-Pin; Leu, Hsieh-Shong; Yen, Che-Chieh; Chang, Feng-Yee

    2012-04-01

    Multi-drug-resistant organisms are increasingly recognized as a global public health issue. Healthcare-associated infection and antimicrobial resistance are also current challenges to the treatment of infectious diseases in Taiwan. Government health policies and the health care systems play a crucial role in determining the efficacy of interventions to contain antimicrobial resistance. National commitment to understand and address the problem is prerequisite. We analyzed and reviewed the antibiotic resistance related policies in Taiwan, USA, WHO and draft antimicrobial stewardship program to control effectively antibiotic resistance and spreading in Taiwan. Antimicrobial stewardship program in Taiwan includes establishment of national inter-sectoral antimicrobial stewardship task force, implementing antimicrobial-resistance management strategies, surveillance of HAI and antimicrobial resistance, conducting hospital infection control, enforcement of appropriate regulations and audit of antimicrobial use through hospital accreditation, inspection and national health insurance payment system. No action today, no cure tomorrow. Taiwan CDC would take a multifaceted, evidence-based approach and make every effort to combat antimicrobial resistance with stakeholders to limit the spread of multi-drug resistant strains and to reduce the generation of antibiotic resistant bacteria in Taiwan.

  3. Triclosan antimicrobial polymers

    OpenAIRE

    Petersen, Richard C.

    2016-01-01

    Triclosan antimicrobial molecular fluctuating energies of nonbonding electron pairs for the oxygen atom by ether bond rotations are reviewed with conformational computational chemistry analyses. Subsequent understanding of triclosan alternating ether bond rotations is able to help explain several material properties in Polymer Science. Unique bond rotation entanglements between triclosan and the polymer chains increase both the mechanical properties of polymer toughness and strength that are ...

  4. Antimicrobial Peptides in Echinoderms

    OpenAIRE

    Li, C; Haug, T; K Stensvåg

    2010-01-01

    Antimicrobial peptides (AMPs) are important immune effector molecules for invertebrates, including echinoderms, which lack a vertebrate-type adaptive immune system. Here we summarize the knowledge of such peptides in echinoderms. Strongylocins are a novel family of cysteine-rich AMPs, recently identified in the sea urchins, Strongylocentrotus droebachiensis and S. purpuratus. Although these molecules present diverse amino acid sequences, they share an identical cysteine arrangement pattern, d...

  5. Antimicrobial Modifications of Polymers

    OpenAIRE

    Sedlarik, Vladimir

    2013-01-01

    This chapter is focused on antimicrobial modifications of polymer materials intended for medical devices production. Firstly, a brief introduction into the field of medical application of polymers is presented. Considering the fact that polymer medical devices are often connected with occurrence of nosocomial infections, the next part refers to this phenomenon and its causes. One of the possibilities of reducing of the infection occurrence is aimed at polymer modification. It is a key topic o...

  6. [Antimicrobial mechanisms of action].

    Science.gov (United States)

    Calvo, Jorge; Martínez-Martínez, Luis

    2009-01-01

    A large number of families and groups of antimicrobial agents are of clinical interest. The mechanisms by which compounds with antibacterial activity inhibit growth or cause bacterial death are varied and depend on the affected targets. The bacterial cell wall-a unique structure in most bacteria that is absent in eukaryotic cells-can be affected in several ways: at different stages of synthesis (fosfomycin, cycloserine) or transport (bacitracin, mureidomycins) of its metabolic precursors, or by a direct action on its structural organization (beta-lactams, glycopeptides). The main drugs affecting the cytoplasmic membrane are polymyxins and daptomycin. Protein synthesis can be blocked by a large variety of compounds that affect any of the phases of this process, including activation (mupirocin), initiation (oxazolidinones, aminoglycosides), binding of the tRNA amino acid complex to ribosomes (tetracyclines, glycylcyclines) and elongation (amphenicols, lincosamides, macrolides, ketolides, streptogramins, fusidic acid). The metabolism of nucleic acids can be altered at the DNA-dependent RNA polymerase or in the process of DNA coiling (quinolones); some compounds affect DNA directly (nitroimidazoles, nitrofurans). Trimethoprim and sulfamides (often used in combination) are examples of antimicrobial agents that block bacterial metabolic pathways. Some compounds are unable to inhibit or kill bacteria in themselves, but can block bacterial mechanisms of resistance, enhancing the activity of other antimicrobials administered in combination. Among this group of agents, only certain beta-lactamase inhibitors are currently in clinical use.

  7. [Neruda and antimicrobial resistance].

    Science.gov (United States)

    Cotera, Alejandro

    2011-07-01

    Antimicrobial resistance has been a problem in medicine, since their incorporation to clinical practice. Numerous papers have been written on the subject. The analysis of two poems by Pablo Neruda "How much does a man live" and "Larynx", included in the volume "Estravagario" and published for the first time in 1957 and 1958, give us an incredible revelation about the concept of resistance. In these poems aureomycin, the first antimicrobial of the family of tetracyclines, was included as a poetic figure and the therapeutic action of antimicrobials was described. "Never so much bugs died I tons of them fell I but the few that remained olive I manifested their perversity". These writings incorporated novel concepts, even for physicians of that time and described the closeness of death that a patient may perceive during the course of a given disease. The capacity of Pablo Neruda to extract the essence of situations and to anticipate to conditions that only years later became clinically relevant problems, is noteworthy.

  8. Human neutrophil antimicrobial activity.

    Science.gov (United States)

    Thomas, E L; Lehrer, R I; Rest, R F

    1988-01-01

    Polymorphonuclear neutrophilic leukocytes (PMNs) take up opsonized microorganisms into phagosomes that fuse with secretory granules in the PMN cytoplasm to form phagolysosomes. Killing and digestion of microorganisms take place within phagolysosomes. Antimicrobial activities in phagolysosomes are divided into two classes. Oxygen (O2)-dependent mechanisms are expressed when PMNs undergo the "respiratory burst." An NADPH oxidase in the phagolysosome membrane is activated and reduces O2 to superoxide (O2-). O2 reduction is the first step in a series of reactions that produce toxic oxidants. For example, .O2- dismutases to hydrogen peroxide (H2O2), and the azurophil granule enzyme myeloperoxidase catalyzes the oxidation of Cl- by H2O2 to yield hypochlorous acid (HOCl). The reaction of HOCl with ammonia and amines modulates the toxicity of this oxidant. O2-independent antimicrobial mechanisms include the activities of lysosomal proteases, other hydrolytic enzymes, and proteins and peptides that bind to microorganisms and disrupt essential processes or structural components. For example, the bactericidal/permeability-increasing protein, cathepsin G, and the defensins are released into phagolysosomes from the azurophil granules. Proposed mechanisms of action of neutrophil antimicrobial agents, their range of microbial targets, and their possible interactions within phagolysosomes are discussed.

  9. Antimicrobial Drugs in the Home

    Centers for Disease Control (CDC) Podcasts

    2006-10-19

    Survey participants in the United Kingdom admitted keeping leftover antimicrobial drugs for future use and taking them without medical advice. Dr. J. Todd Weber, director of CDC's Office of Antimicrobial Resistance, advises against the practice, which can be dangerous and can promote antimicrobial drug resistance.  Created: 10/19/2006 by Emerging Infectious Diseases.   Date Released: 10/26/2006.

  10. Local inflammation induces complement crosstalk which amplifies the antimicrobial response.

    Directory of Open Access Journals (Sweden)

    Jing Zhang

    2009-01-01

    Full Text Available By eliciting inflammatory responses, the human immunosurveillance system notably combats invading pathogens, during which acute phase proteins (CRP and cytokines are elevated markedly. However, the Pseudomonas aeruginosa is a persistent opportunistic pathogen prevalent at the site of local inflammation, and its acquisition of multiple antibiotic-resistance factors poses grave challenges to patient healthcare management. Using blood samples from infected patients, we demonstrate that P. aeruginosa is effectively killed in the plasma under defined local infection-inflammation condition, where slight acidosis and reduced calcium levels (pH 6.5, 2 mM calcium typically prevail. We showed that this powerful antimicrobial activity is provoked by crosstalk between two plasma proteins; CRPratioL-ficolin interaction led to communication between the complement classical and lectin pathways from which two amplification events emerged. Assays for C4 deposition, phagocytosis, and protein competition consistently proved the functional significance of the amplification pathways in boosting complement-mediated antimicrobial activity. The infection-inflammation condition induced a 100-fold increase in CRPratioL-ficolin interaction in a pH- and calcium-sensitive manner. We conclude that the infection-induced local inflammatory conditions trigger a strong interaction between CRPratioL-ficolin, eliciting complement-amplification pathways which are autonomous and which co-exist with and reinforce the classical and lectin pathways. Our findings provide new insights into the host immune response to P. aeruginosa infection under pathological conditions and the potential development of new therapeutic strategies against bacterial infection.

  11. The biochemical basis of antimicrobial responses in Manduca sexta

    Institute of Scientific and Technical Information of China (English)

    Haobo Jiang

    2008-01-01

    Innate immunity is essential for the wellbeing of vertebrates and invertebrates.Key components of this defense system include pattern recognition receptors that bind to infectious agents, extra-and intra-cellular proteins that relay signals, as well as molecules and cells that eliminate pathogens. We have been studying the defense mechanisms in a biochemical model insect, Manduca sexta. In this insect, hemolin, peptidoglycan recognition proteins, β-1,3-glucan recognition proteins and C-type lectins detect microbial surface molecules and induce immune responses such as phagocytosis, nodulation, encapsulation,melanization and production of antimicrobial peptides. Some of these responses are mediated by extracellular serine proteinase pathways. The proteolytic activation of prophenoloxidase (proPO) yields active phenoloxidase (PO) which catalyzes the formation of quinones and melanin for wound healing and microbe killing. M. sexta hemolymph proteinase 14 (HP 14) precursor interacts with peptidoglycan or β- 1,3-glucan, autoactivates,and leads to the activation of other HPs including HP21 and proPO-activating proteinases (PAPs). PAP-1, -2 and -3 cut proPO to generate active PO in the presence of two serine proteinase homologs. Inhibition of the proteinases by serpins and association of the proteinase homologs with bacteria ensure a localized defense reaction. M. sexta HP1, HP6,HP8, HP17 and other proteinases may also participate in proPO activation or processing of sp(a)tzle and plasmatocyte spreading peptide.

  12. Penicillin skin testing: potential implications for antimicrobial stewardship.

    Science.gov (United States)

    Unger, Nathan R; Gauthier, Timothy P; Cheung, Linda W

    2013-08-01

    As the progression of multidrug-resistant organisms and lack of novel antibiotics move us closer toward a potential postantibiotic era, it is paramount to preserve the longevity of current therapeutic agents. Moreover, novel interventions for antimicrobial stewardship programs are integral to combating antimicrobial resistance worldwide. One unique method that may decrease the use of second-line antibiotics (e.g., fluoroquinolones, vancomycin) while facilitating access to a preferred β-lactam regimen in numerous health care settings is a penicillin skin test. Provided that up to 10% of patients have a reported penicillin allergy, of whom ~10% have true IgE-mediated hypersensitivity, significant potential exists to utilize a penicillin skin test to safely identify those who may receive penicillin or a β-lactam antibiotic. In this article, we provide information on the background, associated costs, currently available literature, pharmacists' role, antimicrobial stewardship implications, potential barriers, and misconceptions, as well as future directions associated with the penicillin skin test.

  13. The role of antimicrobial peptides in skin tumorigenesis

    Directory of Open Access Journals (Sweden)

    Małgorzata Marcinkiewicz

    2016-05-01

    Full Text Available Antimicrobial peptides (AMPs, known as “natural antibiotics”, are the first line of defense in humans as effector molecules of the innate immune system of the skin. They present activity against a broad spectrum of bacteria, fungi, parasites and enveloped viruses. An increasing number of studies report altered expression of AMPs in human cancers. Antimicrobial peptides such as human β defensins, human cathelicidin, ribonuclease 7 and psoriasin, a member of S100 proteins, are suggested to play a role in tumor progression and tumor suppression in pre-malignant skin lesions and malignancies. Noticeable changes in AMPs expression in skin tumorigenesis suggest a correlation between peptides and cutaneous cancers, though it is still a matter of discussion. In this article we review recent studies on the relationship between antimicrobial peptides and skin tumorigenesis.

  14. Mutations of Francisella novicida that alter the mechanism of its phagocytosis by murine macrophages.

    Directory of Open Access Journals (Sweden)

    Xin-He Lai

    Full Text Available Infection with the bacterial pathogen Francisella tularensis tularensis (F. tularensis causes tularemia, a serious and debilitating disease. Francisella tularensis novicida strain U112 (abbreviated F. novicida, which is closely related to F. tularensis, is pathogenic for mice but not for man, making it an ideal model system for tularemia. Intracellular pathogens like Francisella inhibit the innate immune response, thereby avoiding immune recognition and death of the infected cell. Because activation of inflammatory pathways may lead to cell death, we reasoned that we could identify bacterial genes involved in inhibiting inflammation by isolating mutants that killed infected cells faster than the wild-type parent. We screened a comprehensive transposon library of F. novicida for mutant strains that increased the rate of cell death following infection in J774 macrophage-like cells, as compared to wild-type F. novicida. Mutations in 28 genes were identified as being hypercytotoxic to both J774 and primary macrophages of which 12 were less virulent in a mouse infection model. Surprisingly, we found that F. novicida with mutations in four genes (lpcC, manB, manC and kdtA were taken up by and killed macrophages at a much higher rate than the parent strain, even upon treatment with cytochalasin D (cytD, a classic inhibitor of macrophage phagocytosis. At least 10-fold more mutant bacteria were internalized by macrophages as compared to the parent strain if the bacteria were first fixed with formaldehyde, suggesting a surface structure is required for the high phagocytosis rate. However, bacteria were required to be viable for macrophage toxicity. The four mutant strains do not make a complete LPS but instead have an exposed lipid A. Interestingly, other mutations that result in an exposed LPS core were not taken up at increased frequency nor did they kill host cells more than the parent. These results suggest an alternative, more efficient macrophage

  15. Phagocytosis (cannibalism) of apoptotic neutrophils by tumor cells in gastric micropapillary carcinomas.

    Science.gov (United States)

    Barresi, Valeria; Branca, Giovanni; Ieni, Antonio; Rigoli, Luciana; Tuccari, Giovanni; Caruso, Rosario Alberto

    2015-05-14

    cytoplasmic vacuoles of tumor cells. These data suggest phagocytosis (cannibalism) of apoptotic neutrophils by micropapillary tumor cells. Tumor cell cannibalism is usually found in aggressive tumors with anaplastic morphology. Our data extend these observations to gastric micropapillary carcinoma: a tumor histotype analogously characterized by aggressive behavior and poor prognosis. The results are of interest because they raise the intriguing possibility that neutrophil cannibalism by tumor cells may be one of the mechanisms favoring tumor growth in gastric micropapillary carcinomas. This is the first study showing phagocytosis (cannibalism) of apoptotic neutrophils by tumor cells in gastric micropapillary carcinomas.

  16. Influence of protein kinase C inhibitor in phagocytosis activity toward Candida sp

    Directory of Open Access Journals (Sweden)

    Adiprayitno Adiprayitno

    2001-09-01

    Full Text Available Protein kinase C isoenzyme family that expresses in all of cells plays a pivotal role in the signal transduction pathway of a variety of hormones, cytokines, neurotransmitter, and growth factors. The immunity against Candida sp is mainly mediated and performed by the T cells and macrophages. The objective of this experiment is to know the influence the protein kinase C inhibitor - bisindolylmaleimides in phagocytosis activity toward Candida sp. The culture of peritoneal macrophage derived from BALB/c mice are treated with bisindolylmaleimides as a protein kinase C inhibitor concentration varied from 5 ng/ml to 100 ng/ml for as long as 10 minute. Then the Candida sp added is observed after every 30 minute for as long as 120 minute. As the experimental design is used the method of factorial and orthogonal polynomial. The data consisting the length of pseudopodia and the number of Candida sp which are phagocytosed are analyzed applying the Anova. One Way Anova to show the differences of each manipulation, the Two Way Anova to show the interaction of manipulations and the Student's t Test to show the differences with control. Statistical test show significant differences on the length of pseudopodia, and phagocytosed Candida sp, at different bisindolylmaleimides concentration (p<0.001 and different observed time (p<0.001. The data show a significant interaction between the bisindolylmaleimides concentration and observed time (p<0.001. The higher the bisindolylmaleimides concentration, the earlier the observed time, the much number the protein kinase C are going inactive and the shorter the length of pseudopodia or the lower the macrophages phagocytic activity toward Candida sp. The result of this experiment indicates that bisindolylmaleimides can inhibit the macrophage mobility and phagocytic activity toward Candida sp. Further experiment in protein kinase C, especially in macrophage, is suggested. (Med J Indones 2001; 10: 150

  17. LyGDI, a novel SHIP-interacting protein, is a negative regulator of FcγR-mediated phagocytosis.

    Science.gov (United States)

    Mehta, Payal; Wavreille, Anne-Sophie; Justiniano, Steven E; Marsh, Rachel L; Yu, Jianhua; Burry, Richard W; Jarjoura, David; Eubank, Timothy; Caligiuri, Michael A; Butchar, Jonathan P; Tridandapani, Susheela

    2011-01-01

    SHIP and SHIP-2 are inositol phosphatases that regulate FcγR-mediated phagocytosis through catalytic as well as non-catalytic mechanisms. In this study we have used two-dimensional fluorescence difference gel electrophoresis (DIGE) analysis to identify downstream signaling proteins that uniquely associate with SHIP or SHIP-2 upon FcγR clustering in human monocytes. We identified LyGDI as a binding partner of SHIP, associating inducibly with the SHIP/Grb2/Shc complex. Immunodepletion and competition experiments with recombinant SHIP domains revealed that Grb2 and the proline-rich domain of SHIP were necessary for SHIP-LyGDI association. Functional studies in primary human monocytes showed that LyGDI sequesters Rac in the cytosol, preventing it from localizing to the membrane. Consistent with this, suppression of LyGDI expression resulted in significantly enhanced FcγR-mediated phagocytosis.

  18. LyGDI, a novel SHIP-interacting protein, is a negative regulator of FcγR-mediated phagocytosis.

    Directory of Open Access Journals (Sweden)

    Payal Mehta

    Full Text Available SHIP and SHIP-2 are inositol phosphatases that regulate FcγR-mediated phagocytosis through catalytic as well as non-catalytic mechanisms. In this study we have used two-dimensional fluorescence difference gel electrophoresis (DIGE analysis to identify downstream signaling proteins that uniquely associate with SHIP or SHIP-2 upon FcγR clustering in human monocytes. We identified LyGDI as a binding partner of SHIP, associating inducibly with the SHIP/Grb2/Shc complex. Immunodepletion and competition experiments with recombinant SHIP domains revealed that Grb2 and the proline-rich domain of SHIP were necessary for SHIP-LyGDI association. Functional studies in primary human monocytes showed that LyGDI sequesters Rac in the cytosol, preventing it from localizing to the membrane. Consistent with this, suppression of LyGDI expression resulted in significantly enhanced FcγR-mediated phagocytosis.

  19. Effect of Bothrops alternatus snake venom on macrophage phagocytosis and superoxide production: participation of protein kinase C

    Directory of Open Access Journals (Sweden)

    SS Setubal

    2011-01-01

    Full Text Available Envenomations caused by different species of Bothrops snakes result in severe local tissue damage, hemorrhage, pain, myonecrosis, and inflammation with a significant leukocyte accumulation at the bite site. However, the activation state of leukocytes is still unclear. According to clinical cases and experimental work, the local effects observed in envenenomation by Bothrops alternatus are mainly the appearance of edema, hemorrhage, and necrosis. In this study we investigated the ability of Bothrops alternatus crude venom to induce macrophage activation. At 6 to 100 ¼g/mL, BaV is not toxic to thioglycollate-elicited macrophages; at 3 and 6 ¼g/mL, it did not interfere in macrophage adhesion or detachment. Moreover, at concentrations of 1.5, 3, and 6 ¼g/mL the venom induced an increase in phagocytosis via complement receptor one hour after incubation. Pharmacological treatment of thioglycollate-elicited macrophages with staurosporine, a protein kinase (PKC inhibitor, abolished phagocytosis, suggesting that PKC may be involved in the increase of serum-opsonized zymosan phagocytosis induced by BaV. Moreover, BaV also induced the production of anion superoxide (O2_ by thioglycollate-elicited macrophages. This BaV stimulated superoxide production was abolished after treating the cells with staurosporine, indicating that PKC is an important signaling pathway for the production of this radical. Based on these results, we suggest that phagocytosis and reactive oxygen species are involved in the pathogenesis of local tissue damage characteristic of Bothrops spp. envenomations.

  20. Opsonisation and phagocytosis of group B meningococci by polymorphonuclear leucocytes: comparison of sulphonamide sensitive and resistant strains.

    OpenAIRE

    Ward, K N; Fleer, A; Verhoef, J; Jones, D M

    1987-01-01

    A large proportion of disease caused by sulphonamide resistant strains of group B type 15 meningococci affects patients 10-24 years. In contrast, disease caused by sulphonamide sensitive strains conforms to the usual pattern, and most infection occurs in early childhood. In an attempt to explain this phenomenon possible differences in susceptibility of resistant and sensitive strains to phagocytosis by polymorphonuclear leucocytes were investigated, using radioactively labelled bacteria. In i...

  1. Antimicrobial stewardship: philosophy versus practice.

    Science.gov (United States)

    Dodds Ashley, Elizabeth S; Kaye, Keith S; DePestel, Daryl D; Hermsen, Elizabeth D

    2014-10-15

    To promote the judicious use of antimicrobials and preserve their usefulness in the setting of growing resistance, a number of policy-making bodies and professional societies have advocated the development of antimicrobial stewardship programs. Although these programs have been implemented at many institutions in the United States, their impact has been difficult to measure. Current recommendations advocate the use of both outcome and process measures as metrics for antimicrobial stewardship. Although patient outcome metrics have the greatest impact on the quality of care, the literature shows that antimicrobial use and costs are the indicators measured most frequently by institutions to justify the effectiveness of antimicrobial stewardship programs. The measurement of more meaningful outcomes has been constrained by difficulties inherent to these measures, lack of funding and resources, and inadequate study designs. Antimicrobial stewardship can be made more credible by refocusing the antimicrobial review process to target specific disease states, reassessing the usefulness of current metrics, and integrating antimicrobial stewardship program initiatives into institutional quality and safety efforts.

  2. Absorbent silver (I) antimicrobial fabrics

    Science.gov (United States)

    In recent years, silver in form of silver ions, has been gaining importance in the wound management as an effective broad-spectrum antimicrobial agent. Silver has a long history as an antimicrobial agent, especially in the treatment of wounds. Alginates and carboxymethyl (CM) cotton contain carboxyl...

  3. Neisseria meningitidis and Escherichia coli are protected from leukocyte phagocytosis by binding to erythrocyte complement receptor 1 in human blood

    DEFF Research Database (Denmark)

    Brekke, O. L.; Hellerud, B. C.; Christiansen, D.

    2011-01-01

    The initial interaction of Gram-negative bacteria with erythrocytes and its implications on leukocyte phagocytosis and oxidative burst in human whole blood were examined. Alexa-labeled Escherichia coli, wild-type H44/76 N. meningitidis and the H44/76lpxA lipopolysaccharide (LPS)-deficient mutant ......-primates and that the bacteria were mainly found in the lungs. In conclusion, complement-dependent binding of Gram-negative bacteria to erythrocyte CR1 decreases phagocytosis and oxidative burst by leukocytes in human whole blood. (C) 2011 Elsevier Ltd. All rights reserved.......The initial interaction of Gram-negative bacteria with erythrocytes and its implications on leukocyte phagocytosis and oxidative burst in human whole blood were examined. Alexa-labeled Escherichia coli, wild-type H44/76 N. meningitidis and the H44/76lpxA lipopolysaccharide (LPS)-deficient mutant...... were incubated with whole blood using lepirudin as anticoagulant which has no adverse effects on complement. Bacteria free in plasma, bound to erythrocytes or phagocytized by granulocytes and monocytes were quantified using flow cytometry. The effects of the C3 inhibitor compstatin, a C5a receptor...

  4. Effect of local immunization of the mammary gland on phagocytosis and intracellular kill of Staphylococcus aureus by polymorphonuclear neutrophils.

    Science.gov (United States)

    Guidry, A J; Paape, M J; Pearson, R E; Williams, W F

    1980-09-01

    Four cows in the latter part of their 2nd, 3rd, or 4th lactations were immunized by multiple intramammary infusions of heat-killed Staphylococcus aureus in 2 quarters. The direct bactericidal effects of milk whey from the immunized and control quarters, before and after immunization, and the ability of these whey to support phagocytosis and intracellular kill were determined by incubating live S aureus with polymorphonuclear neutrophils isolated from milk. Immunoglobulins (Ig) were determined by single radial immunodiffusion. One immunized and 1 control quarter in each cow were challenge exposed with live S aureus and the courses of the infections were determined for 2 weeks. There were significant cow differences in all Ig classes and in percentage of phagocytosis. Immunization resulted in a significant increase in IgA, IgG2, and IgM in the immunized quarters. Whey collected from immunized quarters supported phagocytosis of S aureus by isolated milk polymorphonuclear neutrophils significantly greater than did whey from control quarters. Extracellular live S aureus in the incubation medium was decreased by 59% in whey collected after immunization from immunized quarters. This decrease in extracellular S aureus was associated with a concomitant increase in total intracellular S aureus. However, intracellular live organisms showed no change. This lack of change indicated that the additional S aureus that were phagocytosed were killed. Direct bactericidal effects of whey were not observed. Intracellular live S aureus was not significantly correlated with any of the variables measured.

  5. Effect of N-acetylcysteine on the oxidative burst induced by phagocytosis of bacteria in human leukocytes.

    Science.gov (United States)

    Colomé, J A; Jordá, J; Espinós, D; Bruseghini, L; Esteras, A

    1998-05-01

    The basal peroxide production and the oxidative burst induced by phagocytosis of opsonized E. coli was studied by flow cytometry using dihydrorhodamine 123. The human leukocytes were incubated in the absence and presence of N-acetylcysteine. The oxidative response to the phagocytosis of bacteria differed among cell populations. Thus, 90% of granulocytes and 50% of monocytes showed an oxidative burst in response to opsonized bacteria while less than 1% of lymphocytes showed a fluorescence signal. N-Acetylcysteine (4.7, 9.5, 19, 38 or 76 mM) produced a dose-dependent inhibition of the oxidative response to phagocytosis in the three cellular populations reaching almost complete inhibition for 76 mM. This protective effect of N-acetylcysteine against oxidative stress in leukocytes was obtained without cytotoxicity (assessed by flow cytometry with staining with propidium iodide) or changes in the pH of the medium. These results give further support to the antioxidant effect of N-acetylcysteine in human peripheral blood cells.

  6. Source and role of diacylglycerol formed during phagocytosis of opsonized yeast particles and associated respiratory burst in human neutrophils

    Energy Technology Data Exchange (ETDEWEB)

    Della Bianca, V.; Grzeskowiak, M.; Lissandrini, D.; Rossi, F. (Univ. of Verona (Italy))

    1991-06-28

    The results presented in this paper demonstrate that in human neutrophils phagocytosis of C3b/bi and IgG-opsonized yeast particles is associated with activation of phospholipase D and that this reaction is the main source of diglycerides. The demonstration is based upon the following findings: (1) the challenge of neutrophils with these opsonized particles was followed by a rapid formation of (3H)alkyl-phosphatidic acid (( 3H)alkyl-PA) and (3H)alkyl-diglyceride (( 3H)alkyl-DG) in cells labeled with (3H)alkyl-lyso-phosphatidylcholine; (2) in the presence of ethanol (3H)alkyl-phosphatidylethanol was formed, and accumulation of (3H)alkyl-PA and (3H)alkyl-DG was depressed; (3) propranolol, by inhibiting the dephosphorylation of (3H)alkyl-PA, completely inhibited the accumulation of (3H)alkyl-DG and depressed by about 75% the formation of diglyceride mass. Evidence is also presented that phagocytosis of C3b/bi and IgG-opsonized yeast particles and associated respiratory burst can take place independently of diglyceride formation and of the activity of this second messenger on protein kinase C. In fact: (a) propranolol while completely inhibited the formation of diglyceride mass did not modify either the phagocytosis or respiratory burst; (b) these two processes were insensitive to staurosporine.

  7. Activation-Inactivation Cycling of Rab35 and ARF6 Is Required for Phagocytosis of Zymosan in RAW264 Macrophages

    Directory of Open Access Journals (Sweden)

    Youhei Egami

    2015-01-01

    Full Text Available Phagocytosis of zymosan by phagocytes is a widely used model of microbial recognition by the innate immune system. Live-cell imaging showed that fluorescent protein-fused Rab35 accumulated in the membranes of phagocytic cups and then dissociated from the membranes of newly formed phagosomes. By our novel pull-down assay for Rab35 activity, we found that Rab35 is deactivated immediately after zymosan internalization into the cells. Phagosome formation was inhibited in cells expressing the GDP- or GTP-locked Rab35 mutant. Moreover, the simultaneous expression of ACAP2—a Rab35 effector protein—with GTP-locked Rab35 or the expression of plasma membrane-targeted ACAP2 showed a marked inhibitory effect on phagocytosis through ARF6 inactivation by the GAP activity of ACAP2. ARF6, a substrate for ACAP2, was also localized on the phagocytic cups and dissociated from the membranes of internalized phagosomes. In support of the microscopic observations, ARF6-GTP pull-down experiments showed that ARF6 is transiently activated during phagosome formation. Furthermore, the expression of GDP- or GTP-locked ARF6 mutants also suppresses the uptake of zymosan. These data suggest that the activation-inactivation cycles of Rab35 and ARF6 are required for the uptake of zymosan and that ACAP2 is an important component that links Rab35/ARF6 signaling during phagocytosis of zymosan.

  8. Phagocytosis via complement or Fc-gamma receptors is compromised in monocytes from type 2 diabetes patients with chronic hyperglycemia.

    Directory of Open Access Journals (Sweden)

    Blanca I Restrepo

    Full Text Available Type 2 diabetes patients (DM2 have a higher risk of tuberculosis (TB that may be attributed to functional defects in their mononuclear phagocytes given the critical role of these cells in Mycobacterium tuberculosis containment. Our previous findings suggest that monocytes from DM2 have reduced association with serum-opsonized M. tuberculosis. To determine if this alteration is due to defects in phagocytosis via complement or Fc-gamma receptors (FcγRs, in this study we evaluated the uptake of sheep red blood cells coated with IgG or complement, respectively, by monocytes from individuals with and without DM2. We found that chronic hyperglycemia was significantly associated with reduced phagocytosis via either receptor by univariable and multivariable analyses. This defect was independent of host serum opsonins and flow cytometry data indicated this was not attributed to reduced expression of these phagocytic receptors on DM2 monocytes. The positive correlation between both pathways (R = 0.64; p = 0.003 indicate that monocytes from individuals with chronic hyperglycemia have a defect in the two predominant phagocytic pathways of these cells. Given that phagocytosis is linked to activation of effector mechanisms for bacterial killing, it is likely that this defect is one factor contributing to the higher susceptibility of DM2 patients to pathogens like M. tuberculosis.

  9. Differential timing of antibody-mediated phagocytosis and cell-free killing of invasive African Salmonella allows immune evasion.

    Science.gov (United States)

    Siggins, Matthew K; O'Shaughnessy, Colette M; Pravin, John; Cunningham, Adam F; Henderson, Ian R; Drayson, Mark T; MacLennan, Calman A

    2014-04-01

    Nontyphoidal Salmonellae commonly cause fatal bacteraemia in African children lacking anti-Salmonella antibodies. These are facultative intracellular bacteria capable of cell-free and intracellular survival within macrophages. To better understand the relationship between extracellular and intracellular infection in blood and general mechanisms of Ab-related protection against Salmonella, we used human blood and sera to measure kinetics of Ab and complement deposition, serum-mediated bactericidal killing and phagocytosis of invasive African Salmonella enterica serovar Typhimurium D23580. Binding of antibodies peaked by 30 s, but C3 deposition lagged behind, peaking after 2-4 min. C5b-9 deposition was undetectable until between 2 and 6 min and peaked after 10 min, after which time an increase in serum-mediated killing occurred. In contrast, intracellular, opsonized Salmonellae were readily detectable within 5 min. By 10 min, around half of monocytes and most neutrophils contained bacteria. The same kinetics of serum-mediated killing and phagocytosis were observed with S. enterica Typhimurium laboratory strain SL1344, and the S. enterica Enteritidis African invasive isolate D24954 and laboratory strain PT4. The differential kinetics between cell-free killing and phagocytosis of invasive nontyphoidal Salmonella allows these bacteria to escape the blood and establish intracellular infection before they are killed by the membrane attack complex.

  10. Antibody inhibition of polymorphonuclear phagocytosis. Dissociation of bacterial attachment and bacterial killing.

    Science.gov (United States)

    Crowley, J P; Valeri, C R

    1980-06-01

    The inhibition of killing of Staphylococcus aureus 502A by PMNs treated with the IgG fraction of serum from a group of patients with demonstrable leukocyte antibodies was investigated. The uptake of opsonized thymidine-labeled S. aureus 502A by PMNs treated with allogeneic antibody was essentially unimpaired, despite significantly decreased killing. The findings were similar to bacteria opsonized by serum complement or bacteria opsonized with specific lapine antibody. An increased proportion of PMN-bound bacteria susceptible to lysis by lysostaphin indicated a reduced rate of translocation of bacteria from the surface of allogeneic antibody-treated PMNs. Antibody did not stimulate the basal oxidative metabolism, but the oxidative metabolism of antibody-treated PMNs during phagocytosis was increased. Although the precise mechanism of inhibition of PMN killing by antibody is uncertain, the data suggest that the impairment of bacterial killing by PMNs treated with allogeneic leukocyte antibody is associated with inefficient translocation of bacteria into phagolysosomes rather than by interference with the binding of bacteria to specific PMN opsonic receptors.

  11. A novel strain of Bacteroides fragilis enhances phagocytosis and polarises M1 macrophages

    Science.gov (United States)

    Deng, Huimin; Li, Zhengchao; Tan, Yafang; Guo, Zhaobiao; Liu, Yangyang; Wang, Ye; Yuan, Yuan; Yang, Ruifu; Bi, Yujing; Bai, Yang; Zhi, Fachao

    2016-01-01

    Commensal Bacteroides fragilis possesses immune-regulatory characteristics. Consequently, it has been proposed as a potential novel probiotic because of its therapeutic effects on immune imbalance, mental disorders and inflammatory diseases. Macrophages play a central role in the immune response, developing either a classical-M1 or an alternative-M2 phenotype after stimulation with various signals. The interactions between macrophages and B. fragilis, however, remain to be defined. Here, a new isolate of B. fragilis, ZY-312, was shown to possess admirable properties, including tolerance to simulated gastric fluid, intestinal fluid and ox bile, and good safety (MOI = 100, 200) and adherent ability (MOI = 100) to LoVo cells. Isolate ZY-312 cell lysate promoted phagocytosis of fluorescent microspheres and pathogenic bacteria in bone marrow-derived macrophage (BMDM) cells. Gene expression of IL-12, iNOS and IL-1β in BMDM cells was increased after treatment with ZY-312, indicating the induction of M1 macrophages, consistent with enhanced secretion of NO. Cell surface expression of CD80 and CD86 was also increased. This study is the first to demonstrate that B. fragilis enhances the phagocytic functions of macrophages, polarising them to an M1 phenotype. Our findings provide insight into the close relationship between B. fragilis and the innate immune system. PMID:27381366

  12. Glycoengineering of therapeutic antibodies enhances monocyte/macrophage-mediated phagocytosis and cytotoxicity.

    Science.gov (United States)

    Herter, Sylvia; Birk, Martina C; Klein, Christian; Gerdes, Christian; Umana, Pablo; Bacac, Marina

    2014-03-01

    Therapeutic Abs possess several clinically relevant mechanisms of action including perturbation of tumor cell signaling, activation of complement-dependent cytotoxicity, Ab-dependent cellular cytotoxicity (ADCC), Ab-dependent cellular phagocytosis (ADCP), and induction of adaptive immunity. In view of the important role of phagocytic lineage cells in the mechanism of action of therapeutic Abs, we analyzed FcγR receptor-dependent effector functions of monocytes and macrophages triggered by glycoengineered (GE) Abs (having enhanced FcγRIIIa [CD16a] binding affinity) versus their wild-type (WT) counterparts under different experimental conditions. We first defined the precise FcγR repertoire on classical and nonclassical intermediate monocytes--M1 and M2c macrophage populations. We further show that WT and GE Abs display comparable binding and induce similar effector functions (ADCC and ADCP) in the absence of nonspecific, endogenous IgGs. However, in the presence of these IgGs (i.e., in a situation that more closely mimics physiologic conditions), GE Abs display significantly superior binding and promote stronger monocyte and macrophage activity. These data show that in addition to enhancing CD16a-dependent NK cell cytotoxicity, glycoengineering also enhances monocyte and macrophage phagocytic and cytotoxic activities through enhanced binding to CD16a under conditions that more closely resemble the physiologic setting.

  13. An amoeba phagocytosis model reveals a novel developmental switch in the insect pathogen Bacillus thuringiensis.

    Science.gov (United States)

    Beeton, M L; Atkinson, D J; Waterfield, N R

    2013-02-01

    The Bacillus cereus group bacteria contain pathogens of economic and medical importance. From security and health perspectives, the lethal mammalian pathogen Bacillus anthracis remains a serious threat. In addition the potent insect pathogen Bacillus thuringiensis is extensively used as a biological control agent for insect pests. This relies upon the industrial scale induction of bacterial spore formation with the associated production of orally toxic Cry-toxins. Understanding the ecology and potential alternative developmental fates of these bacteria is therefore important. Here we describe the use of an amoeba host model to investigate the influence of environmental bactivorous protists on both spores and vegetative cells of these pathogens. We demonstrate that the bacteria can respond to different densities of amoeba by adopting different behaviours and developmental fates. We show that spores will germinate in response to factors excreted by the amoeba, and that the bacteria can grow and reproduce on these factors. We show that in low densities of amoeba, that the bacteria will seek to colonise the surface of the amoeba as micro-colonies, resisting phagocytosis. At high amoeba densities, the bacteria change morphology into long filaments and macroscopic rope-like structures which cannot be ingested due to size exclusion. We suggest these developmental fates are likely to be important both in the ecology of these bacteria and also during animal host colonisation and immune evasion.

  14. Sialylation of Campylobacter jejuni lipo-oligosaccharides: impact on phagocytosis and cytokine production in mice.

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    Ruth Huizinga

    Full Text Available BACKGROUND: Guillain-Barré syndrome (GBS is a post-infectious polyradiculoneuropathy, frequently associated with antecedent Campylobacter jejuni (C. jejuni infection. The presence of sialic acid on C. jejuni lipo-oligosaccharide (LOS is considered a risk factor for development of GBS as it crucially determines the structural homology between LOS and gangliosides, explaining the induction of cross-reactive neurotoxic antibodies. Sialylated C. jejuni are recognised by TLR4 and sialoadhesin; however, the functional implications of these interactions in vivo are unknown. METHODOLOGY/PRINCIPAL FINDINGS: In this study we investigated the effects of bacterial sialylation on phagocytosis and cytokine secretion by mouse myeloid cells in vitro and in vivo. Using fluorescently labelled GM1a/GD1a ganglioside-mimicking C. jejuni strains and corresponding (Cst-II-mutant control strains lacking sialic acid, we show that sialylated C. jejuni was more efficiently phagocytosed in vitro by BM-MΦ, but not by BM-DC. In addition, LOS sialylation increased the production of IL-10, IL-6 and IFN-β by both BM-MΦ and BM-DC. Subsequent in vivo experiments revealed that sialylation augmented the deposition of fluorescent bacteria in splenic DC, but not macrophages. In addition, sialylation significantly amplified the production of type I interferons, which was independent of pDC. CONCLUSIONS/SIGNIFICANCE: These results identify novel immune stimulatory effects of C. jejuni sialylation, which may be important in inducing cross-reactive humoral responses that cause GBS.

  15. Flow cytometric quantitation of phagocytosis in heparinized complete blood with latex particles and Candida albicans

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    Jesús M. Egido

    1997-12-01

    Full Text Available We report a rapid method for the flow cytometric quantitation of phagocytosis in heparinized complete peripherial blood (HCPB, using commercially available phycoerythrin-conjugated latex particles of 1µm diameter. The method is faster and shows greater reproducibility than Bjerknes' (1984 standard technique using propidium iodide-stained Candida albicans, conventionally applied to the leukocytic layer of peripherial blood but here modified for HCPB. We also report a modification of Bjerknes' Intracellular Killing Test to allow its application to HCPB.Se da cuenta de un método rápido para la cuantización del flujo citométrico de la fagocitosis en sangre periférica completamente heparinizada (HCPB, mediante la utilización de partículas de látex phycoerythrin-conjugadas de 1µm de diámetro disponibles comercialmente. El método es más rápido y presenta mayor reproducibilidad que la técnica estandar de Bjerknes' (1984 utilizando propidium iodide-teñida Candida albicans, aplicada convencionalmente a la capa leucocitica de sangre periférica pero modificada por HCPB. Tambien damos cuenta de una modificación de Bjerknes' Intracellular Killing Test para permitir su aplicación a HCPB.

  16. Functional roles of mannose-binding protein in the adhesion, cytotoxicity and phagocytosis of Acanthamoeba castellanii.

    Science.gov (United States)

    Kim, Jong-Hyun; Matin, Abdul; Shin, Ho-Joon; Park, Hyun; Yoo, Kyung-Tae; Yuan, Xi-Zhe; Kim, Kwang Sik; Jung, Suk-Yul

    2012-10-01

    Acanthamoeba castellanii is a single-celled protozoan that is widely distributed in the environment and is a well-known of causing human keratitis, a vision-threatening infection. In this study, an ethyl methane sulfonate (EMS) and a selection of saccharide were applied to A. castellanii by chemical mutagenesis. To understand the functional roles of a mannose-binding protein (MBP). A. castellanii were treated with methyl-alpha-D-mannopyranoside abbreviated Man, with and without the EMS pre-treatment, and their adhesion and cytotoxicity were analyzed, using a human brain microvascular endothelial cell (HBMEC) as the target cell. Both EMS and Man mutants exhibited significantly decreased levels of MBP expression and cytotoxicity to HBMEC, but showed similar levels of binding to HBMEC, as compared with the wild type. Of interest was that the exogenous mannose inhibited amoebae (i.e., Man mutant) binding to the HBMEC by <20%. Only the mutant Man exhibited a significant decrease in bacterial uptake, as compared to the wild type, 0.020 vs 0.032 (p<0.05) and proteolytic activity. The results showed that MBP should be clearly provided as the pathogenic target candidate, to further target-based therapy, but EMS mutation should not be associated with initial adhesion and phagocytosis of A. castellanii.

  17. Development of bactericidal capacity and phagocytosis-associated metabolism of fetal pig leukocytes.

    Science.gov (United States)

    Holmes, B; Day, N; Haseman, J; Good, R A

    1972-02-01

    Evidence that the bactericidal ability and the stimulated oxidative metabolism of leukocytes appear in parallel during fetal development of the Minnesota Miniature pig has been obtained by application of the techniques applied to studies of human cells. It was demonstrated that leukocytes from 87- to 90-day fetuses were fully capable of ingesting Staphylococcus aureus but greatly diminished in bactericidal capacity as compared to leukocytes of older fetuses and adults. Although resting levels of oxygen consumption and hexose monophosphate pathway activity of leukocytes from the younger fetuses compared well with those of leukocytes from older animals, the phagocytosis-stimulated increments of metabolism were much less at 87 to 90 days of gestation than at later developmental stages. Both bactericidal capacity and increased metabolism of leukocytes reach adult levels by 100 days of gestation (normal gestation period of 115 to 120 days). Acrylamide gels stained for reduced nicotinamide adenine dinucleotide (NADH) and NADH phosphate (NADPH) diaphorase activity after disc electrophoresis of leukocyte extracts revealed normal mobility and intensity of NADH diaphorase bands. Three NADPH diaphorase bands were present in adult leukocyte extracts. Only the fast-migrating NADPH diaphorase band of 87- to 90-day cells stained with decreased intensity. This "deficiency" was no longer present at the later fetal period. The fast-migrating NADPH diaphorase band may represent an electron transfer protein which functions in cyanide-insensitive respiration of the leukocytes of the pig.

  18. A TRP channel in the lysosome regulates large particle phagocytosis via focal exocytosis.

    Science.gov (United States)

    Samie, Mohammad; Wang, Xiang; Zhang, Xiaoli; Goschka, Andrew; Li, Xinran; Cheng, Xiping; Gregg, Evan; Azar, Marlene; Zhuo, Yue; Garrity, Abigail G; Gao, Qiong; Slaugenhaupt, Susan; Pickel, Jim; Zolov, Sergey N; Weisman, Lois S; Lenk, Guy M; Titus, Steve; Bryant-Genevier, Marthe; Southall, Noel; Juan, Marugan; Ferrer, Marc; Xu, Haoxing

    2013-09-16

    Phagocytosis of large extracellular particles such as apoptotic bodies requires delivery of the intracellular endosomal and lysosomal membranes to form plasmalemmal pseudopods. Here, we identified mucolipin TRP channel 1 (TRPML1) as the key lysosomal Ca2+ channel regulating focal exocytosis and phagosome biogenesis. Both particle ingestion and lysosomal exocytosis are inhibited by synthetic TRPML1 blockers and are defective in macrophages isolated from TRPML1 knockout mice. Furthermore, TRPML1 overexpression and TRPML1 agonists facilitate both lysosomal exocytosis and particle uptake. Using time-lapse confocal imaging and direct patch clamping of phagosomal membranes, we found that particle binding induces lysosomal PI(3,5)P2 elevation to trigger TRPML1-mediated lysosomal Ca2+ release specifically at the site of uptake, rapidly delivering TRPML1-resident lysosomal membranes to nascent phagosomes via lysosomal exocytosis. Thus phagocytic ingestion of large particles activates a phosphoinositide- and Ca2+-dependent exocytosis pathway to provide membranes necessary for pseudopod extension, leading to clearance of senescent and apoptotic cells in vivo.

  19. CD63 Promotes Hemocyte-Mediated Phagocytosis in the Clam, Paphia undulata

    Directory of Open Access Journals (Sweden)

    Mingjia Yu

    2016-01-01

    Full Text Available As one of the surface membrane proteins of tetraspanin family, CD63 plays a crucial role in cellular trafficking and endocytosis, which also is associated with activation of a wide variety of immune cells. Here, the homolog of CD63 was characterized from one marine mollusk, Paphia undulata, which is designated as Pu-CD63. The complete cDNA of Pu-CD63 is 1,738 bp in length with an open reading frame (ORF of 849 bp, encoding a 282 amino acid protein with four putative hydrophobic transmembrane helixes. Bioinformatic analysis revealed that Pu-CD63 contains one putative YXXØ consensus motif of “110-YVII-113” and one N-glycosylation site “155-NGT-157” within the large extracellular loop (LEL region, supporting its conserved function in plasma membrane and endosomal/lysosomal trafficking. Moreover, temporal expression profile analysis demonstrates a drastic induction in the expression of CD63 in hemocytes after pathogenic challenge with either V. parahaemolyticus or V. alginolyticus. By performing dsRNA-mediate RNAi knockdowns of CD63, a dramatic reduction in hemocytes phagocytic activity to pathogenic Vibrio is recorded by flow cytometry, revealing the definite role of Pu-CD63 in promoting hemocyte-mediated phagocytosis. Therefore, our work has greatly enhanced our understanding about primitive character of innate immunity in marine mollusk.

  20. Aspergillus Cell Wall Melanin Blocks LC3-Associated Phagocytosis to Promote Pathogenicity.

    Science.gov (United States)

    Akoumianaki, Tonia; Kyrmizi, Irene; Valsecchi, Isabel; Gresnigt, Mark S; Samonis, George; Drakos, Elias; Boumpas, Dimitrios; Muszkieta, Laetitia; Prevost, Marie-Christine; Kontoyiannis, Dimitrios P; Chavakis, Triantafyllos; Netea, Mihai G; van de Veerdonk, Frank L; Brakhage, Axel A; El-Benna, Jamel; Beauvais, Anne; Latge, Jean-Paul; Chamilos, Georgios

    2016-01-13

    Concealing pathogen-associated molecular patterns (PAMPs) is a principal strategy used by fungi to avoid immune recognition. Surface exposure of PAMPs during germination can leave the pathogen vulnerable. Accordingly, β-glucan surface exposure during Aspergillus fumigatus germination activates an Atg5-dependent autophagy pathway termed LC3-associated phagocytosis (LAP), which promotes fungal killing. We found that LAP activation also requires the genetic, biochemical or biological (germination) removal of A. fumigatus cell wall melanin. The attenuated virulence of melanin-deficient A. fumigatus is restored in Atg5-deficient macrophages and in mice upon conditional inactivation of Atg5 in hematopoietic cells. Mechanistically, Aspergillus melanin inhibits NADPH oxidase-dependent activation of LAP by excluding the p22phox subunit from the phagosome. Thus, two events that occur concomitantly during germination of airborne fungi, surface exposure of PAMPs and melanin removal, are necessary for LAP activation and fungal killing. LAP blockade is a general property of melanin pigments, a finding with broad physiological implications.

  1. Oxygen radicals in lung carcinogenesis accompanying phagocytosis of diesel exhaust particles.

    Science.gov (United States)

    Ichinose, T; Yamanushi, T; Seto, H; Sagai, M

    1997-09-01

    We sought to examine the involvement of oxygen radicals derived from phagocytosis process in lung carcinogenesis induced by diesel exhaust particles (DEP). The carcinogenic response and formation of 8-hydroxydeoxyguanosine (8-OHdG) were examined in the lungs of mice intratracheally injected with washed DEP (WDEP), DEP, or nontoxic control particles of titanium dioxide (TiO2). After 10 weekly treatments with these particles, the formation of 8-OHdG in the lungs of mice treated with WDEP or DEP showed a significant increase, but not in those treated with TiO2. After 12 months, the incidence of lung tumors in mice treated with WDEP or DEP was higher than that of mice treated with vehicle by 2.3- and 3.1-fold, respectively. A significant difference in the incidence of tumors was found between the vehicle group and DEP-treated group. Treatment with TiO2 had no effect on the incidence of lung tumors. The formation of 8-OHdG in mice treated with these particles was significantly correlated with the development of lung tumors. These results suggest that the induction of DNA damage by oxygen radicals may be an important factor in the initiation of WDEP- and DEP-induced lung carcinogenesis, and that oxygen radicals derived from the phagocytic process may play a role in 8-OHdG formation induced by DEP.

  2. Igg Subclasses Targeting the Flagella of Salmonella enterica Serovar Typhimurium Can Mediate Phagocytosis and Bacterial Killing

    Science.gov (United States)

    Goh, Yun Shan; Armour, Kathryn L; Clark, Michael R; Grant, Andrew J; Mastroeni, Pietro

    2016-01-01

    Invasive non-typhoidal Salmonella are a common cause of invasive disease in immuno-compromised individuals and in children. Multi-drug resistance poses challenges to disease control, with a critical need for effective vaccines. Flagellin is an attractive vaccine candidate due to surface exposure and high epitope copy number, but its potential as a target for opsonophacytic antibodies is unclear. We examined the effect of targeting flagella with different classes of IgG on the interaction between Salmonella Typhimurium and a human phagocyte-like cell line, THP-1. We tagged the FliC flagellar protein with a foreign CD52 mimotope (TSSPSAD) and bacteria were opsonized with a panel of humanised CD52 antibodies with the same antigen-binding V-region, but different constant regions. We found that IgG binding to flagella increases bacterial phagocytosis and reduces viable intracellular bacterial numbers. Opsonisation with IgG3, followed by IgG1, IgG4, and IgG2, resulted in the highest level of bacterial uptake and in the highest reduction in the intracellular load of viable bacteria. Taken together, our data provide proof-of-principle evidence that targeting flagella with antibodies can increase the antibacterial function of host cells, with IgG3 being the most potent subclass. These data will assist the rational design of urgently needed, optimised vaccines against iNTS disease. PMID:27366588

  3. The role of white spot syndrome virus (WSSV) VP466 protein in shrimp antiviral phagocytosis.

    Science.gov (United States)

    Ye, Ting; Zong, Rongrong; Zhang, Xiaobo

    2012-08-01

    Widespread evidence indicates that the structural proteins of virus play very important roles in virus-host interactions. However, the effect of viral proteins on host immunity has not been addressed. Our previous studies revealed that the host shrimp Rab6 (termed as PjRab previously), tropomyosin, β-actin and the white spot syndrome virus (WSSV) envelope protein VP466 formed a complex. In this study, the VP466 protein was shown to be able to bind host Rab6 protein and increase its GTPase activity in vivo and vitro. Thus, VP466 could function as a GTPase-activating protein (GAP) of Rab6. In the VP466-Rab-actin pathway, the increase of the Rab6 activity induced rearrangements of the actin cytoskeleton, resulting in the formation of actin stress fibers which promoted the phagocytosis against virus. Therefore our findings revealed that a viral protein could be employed by host to initiate the host immunity, representing a novel molecular mechanism in the virus-host interaction. Our study would help to better understand the molecular events in immune response against virus infection in invertebrates.

  4. Effect of Grewia asiatica fruit on glycemic index and phagocytosis tested in healthy human subjects.

    Science.gov (United States)

    Mesaik, Muhammad Ahmed; Ahmed, Asif; Khalid, Ahmed Shukralla; Jan, Saleem; Siddiqui, Afaq Ahmed; Perveen, Shahida; Azim, Muhammad Kamran

    2013-01-01

    The Grewia asiatica (commonly known as Phalsa or Fasla) is a shrub or small tree found in southern Asia. It produces purple to black color fruit when ripe. In folk medicine the edible Grewia asiatica fruit is used in a number of pathological conditions. The current study described the effects of Grewia asiatica fruit on glycemic index (GI) and phagocytosis in healthy non-diabetic human subjects. The results showed that Grewia asiatica fruit has low GI value of 5.34 with modest hypoglycemic activity. Luminol-enhanced chemiluminescence assay was carried out to determine the production of reactive oxygen species (ROS) in the oxidative burst activity of whole blood. ROS production was found to be significantly affected, having the 78.3, 58.6 and 30.8% when the subjects were fed with D-glucose, mixture of D-glucose and Grewia asiatica fruit and Grewia asiatica fruit alone respectively as compared to the control. The aqueous, methanolic and butanolic extracts of Grewia asiatica fruits were found to produce a stimulatory effect on ROS production however; the chloroform, hexane and ethanol-acetate extracted exerted significant inhibitory effect. These results demonstrated that Grewia asiatica fruit has desirable effects on blood glucose metabolism manifested as low glycemic response and modulation of ROS production.

  5. Antimicrobial screening of Mnium stellare

    Directory of Open Access Journals (Sweden)

    Kerem Canli

    2015-06-01

    Full Text Available Many plants contain active substances that are known to be effective in both enhancing the wound healing process and lowering the incidence of wound infections. Previous studies have shown that bryophytes produce a variety of secondary metabolites that present pharmaceutical activities including antimicrobial activity against various pathogenic bacteria and fungi. The aim of this study was to investigate the antimicrobial activity of Mnium stellare against 17 bacterial and 1 fungal strains. Our present study has shown that the ethanol extract of M. stellare has antimicrobial activity against several Gram positive and Gram negative microorganism tested, but its antimicrobial activity is notable especially against B. subtilis, S. typhimirium, S. aureus, S. carnosus, and S. epidermidis. These results are the very first report of the antimicrobial activity of M. stellare.

  6. How to fight antimicrobial resistance.

    Science.gov (United States)

    Foucault, Cédric; Brouqui, Philippe

    2007-03-01

    Antimicrobial misuse results in the development of resistance and superbugs. Over recent decades, resistance has been increasing despite continuing efforts to control it, resulting in increased mortality and cost. Many authorities have proposed local, regional and national guidelines to fight against this phenomenon, and the usefulness of these programmes has been evaluated. Multifaceted intervention seems to be the most efficient method to control antimicrobial resistance. Monitoring of bacterial resistance and antibiotic use is essential, and the methodology has now been homogenized. The implementation of guidelines and infection control measures does not control antimicrobial resistance and needs to be reinforced by associated measures. Educational programmes and rotation policies have not been evaluated sufficiently in the literature. Combination antimicrobial therapy is inefficient in controlling antimicrobial resistance.

  7. Antimicrobial resistance in Canada

    Science.gov (United States)

    Conly, John

    2002-01-01

    Antibiotic resistance has increased rapidly during the last decade, creating a serious threat to the treatment of infectious diseases. Canada is no exception to this worldwide phenomenon. Data from the Canadian Nosocomial Infection Surveillance Program have revealed that the incidence of methicillin-resistant Staphylococcus aureus, as a proportion of S. aureus isolates, increased from 1% in 1995 to 8% by the end of 2000, and vancomycin-resistant enterococcus has been documented in all 10 provinces since the first reported outbreak in 1995. The prevalence of nonsusceptible Streptococcus pneumoniae in Canada in 2000 was found to be 12%. Human antimicrobial prescriptions, adjusted for differences in the population, declined 11% based on the total number of prescriptions dispensed between 1995 and 2000. There was also a 21% decrease in β-lactam prescriptions during this same period. These data suggest that systematic efforts to reduce unnecessary prescribing of antimicrobials to outpatients in Canada, beginning after a national consensus conference in 1997, may be having an impact. There is, however, still a need for continued concerted efforts on a national, provincial and regional level to quell the rising tide of antibiotic resistance. PMID:12406948

  8. From amino acids polymers, antimicrobial peptides, and histones, to their possible role in the pathogenesis of septic shock: a historical perspective

    Science.gov (United States)

    Ginsburg, Isaac; van Heerden, Peter Vernon; Koren, Erez

    2017-01-01

    This paper describes the evolution of our understanding of the biological role played by synthetic and natural antimicrobial cationic peptides and by the highly basic nuclear histones as modulators of infection, postinfectious sequelae, trauma, and coagulation phenomena. The authors discuss the effects of the synthetic polymers of basic poly α amino acids, poly l-lysine, and poly l-arginine on blood coagulation, fibrinolysis, bacterial killing, and blood vessels; the properties of natural and synthetic antimicrobial cationic peptides as potential replacements or adjuncts to antibiotics; polycations as opsonizing agents promoting endocytosis/phagocytosis; polycations and muramidases as activators of autolytic wall enzymes in bacteria, causing bacteriolysis and tissue damage; and polycations and nuclear histones as potential virulence factors and as markers of sepsis, septic shock, disseminated intravasclar coagulopathy, acute lung injury, pancreatitis, trauma, and other additional clinical disorders PMID:28203100

  9. Macrophage Polarization Modulates FcγR- and CD13-Mediated Phagocytosis and Reactive Oxygen Species Production, Independently of Receptor Membrane Expression

    Science.gov (United States)

    Mendoza-Coronel, Elizabeth; Ortega, Enrique

    2017-01-01

    In response to microenvironmental cues, macrophages undergo a profound phenotypic transformation acquiring distinct activation phenotypes ranging from pro-inflammatory (M1) to anti-inflammatory (M2). To study how activation phenotype influences phagocytosis and production of reactive oxygen species (ROS) mediated by receptors for IgG antibodies (Fcγ receptors) and by CD13, human monocyte-derived macrophages were polarized to distinct phenotypes using IFN-γ (Mϕ-IFN-γ), IL-4 (Mϕ-IL-4), or IL-10 (Mϕ-IL-10). Phenotypically, Mϕ-IFN-γ were characterized as CD14+CD80+CD86+ cells, Mϕ-IL-4 as CD209highCD206+CD11b+CD14low, and Mϕ-IL-10 as CD16+CD163+ cells. Compared to non-polarized macrophages, FcγRI expression increased in Mϕ-IFN-γ and Mϕ-IL-10 and FcγRIII expression increased in Mϕ-IL-10. None of the polarizing cytokines modified FcγRII or CD13 expression. Functionally, we found that cytokine-mediated activation significantly and distinctively affected FcγR- and CD13-mediated phagocytosis and ROS generation. Compared to non-polarized macrophages, FcγRI-, FcγRII-, and CD13-mediated phagocytosis was significantly increased in Mϕ-IL-10 and decreased in Mϕ-IFN-γ, although both cytokines significantly upregulated FcγRI expression. IL-10 also increased phagocytosis of Escherichia coli, showing that the effect of IL-10 on macrophage phagocytosis is not specific for a particular receptor. Interestingly, Mϕ-IL-4, which showed poor FcγR- and CD13-mediated phagocytosis, showed very high phagocytosis of E. coli and zymosan. Coupled with phagocytosis, macrophages produce ROS that contribute to microbial killing. As expected, Mϕ-IFN-γ showed significant production of ROS after FcγRI-, FcγRII-, or CD13-mediated phagocytosis. Unexpectedly, we found that Mϕ-IL-10 can also produce ROS after simultaneous stimulation through several phagocytic receptors, as coaggregation of FcγRI/FcγRII/CD13 induced a belated but significant ROS production. Together, these

  10. Salivary Antimicrobial Peptides in Early Detection of Periodontitis

    Directory of Open Access Journals (Sweden)

    Guliz N. eGuncu

    2015-12-01

    Full Text Available In the pathogenesis of periodontitis, an infection-induced inflammatory disease of the tooth-supporting tissues, there is a complex interaction between the subgingival microbiota and host tissues. A periodontal diagnostic tool for detecting the initiation and progression of the disease, monitoring the response to therapy, or measuring the degree of susceptibility to future disease progression has been of interest for a long time. The value of various enzymes, proteins, and immunoglobulins, which are abundant constituents of saliva, as potential biomarkers has been recognized and extensively investigated for periodontal diseases. Gingival defensins and cathelicidins are small cationic antimicrobial peptides that play an important role in innate immune response. However, their applicability as salivary biomarkers is still under debate. The present review focuses on proteomic biomarkers and antimicrobial peptides, in particular, to be used at early phases of periodontitis.

  11. Salivary Antimicrobial Peptides in Early Detection of Periodontitis.

    Science.gov (United States)

    Güncü, Güliz N; Yilmaz, Dogukan; Könönen, Eija; Gürsoy, Ulvi K

    2015-01-01

    In the pathogenesis of periodontitis, an infection-induced inflammatory disease of the tooth-supporting tissues, there is a complex interaction between the subgingival microbiota and host tissues. A periodontal diagnostic tool for detecting the initiation and progression of the disease, monitoring the response to therapy, or measuring the degree of susceptibility to future disease progression has been of interest for a long time. The value of various enzymes, proteins, and immunoglobulins, which are abundant constituents of saliva, as potential biomarkers has been recognized and extensively investigated for periodontal diseases. Gingival defensins and cathelicidins are small cationic antimicrobial peptides that play an important role in innate immune response. However, their applicability as salivary biomarkers is still under debate. The present review focuses on proteomic biomarkers and antimicrobial peptides, in particular, to be used at early phases of periodontitis.

  12. Novel Formulations for Antimicrobial Peptides

    Directory of Open Access Journals (Sweden)

    Ana Maria Carmona-Ribeiro

    2014-10-01

    Full Text Available Peptides in general hold much promise as a major ingredient in novel supramolecular assemblies. They may become essential in vaccine design, antimicrobial chemotherapy, cancer immunotherapy, food preservation, organs transplants, design of novel materials for dentistry, formulations against diabetes and other important strategical applications. This review discusses how novel formulations may improve the therapeutic index of antimicrobial peptides by protecting their activity and improving their bioavailability. The diversity of novel formulations using lipids, liposomes, nanoparticles, polymers, micelles, etc., within the limits of nanotechnology may also provide novel applications going beyond antimicrobial chemotherapy.

  13. Antimicrobial resistance of thermophilic Campylobacter

    DEFF Research Database (Denmark)

    Aarestrup, Frank Møller; Engberg, J.

    2001-01-01

    Campylobacter has become the leading cause of zoonotic enteric infections in developed and developing countries world-wide. Antimicrobial resistance has emerged among Campylobacter mainly as a consequence of the use of antimicrobial agents in food animal production. Resistance to drugs of choice...... for the treatment of infections, macrolides and fluoroquinolones has emerged as a clinical problem and interventions to reduce this are recommended. Resistance to fluoroquinolones and macrolides is mediated by chromosomal mutations. Resistance to other relevant antimicrobial agents, mediated by acquired resistance...

  14. Antimicrobial properties of hemoglobin.

    Science.gov (United States)

    Sheshadri, Preethi; Abraham, Jayanthi

    2012-12-01

    Hemoglobin consists of a heme containing component and a globin unit. It exists as a tetramer with 2 α subunits and 2 β subunits in adults and with 2 α subunits and 2 γ chains in infants. On proteolytic cleavage, hemoglobin breaks down to produce many biologically active compounds, among which are hemocidins, those which exhibit antimicrobial property. The generation of these peptides does not depend on the blood group, Rhesus factor, age and sex of the healthy donors. The microbicidal activity has been observed against a variety of gram positive and Gram-negative bacteria, and against filamentous fungi, yeast and even certain parasites. The discovery of hemocidins opens a new field for research into the details of the peptides acting as second line of defence in boosting the innate immune system of the organisms.

  15. Effect of p-cymene on chemotaxis, phagocytosis and leukocyte behaviors

    Directory of Open Access Journals (Sweden)

    Raquel Kummer

    2015-03-01

    Full Text Available Summary. In this study, we investigated the effects of p-cymene (CYM in vitro and in vivo on leukocyte activity. In the cell viability assay, CYM (3, 10, 30, 90 g/mL had low cytotoxicity. In vitro chemotaxis revealed that CYM (3, 10, 30, 60 g/mL promoted a significant reduction of neutrophil migration toward fMLP, but not toward LTB4 stimulation. In carrageenan-induced peritonitis, CYM (100, 200, 400 mg/kg decreased the infiltration of peritoneal exudate leukocytes and of polymorphonuclear leukocytes. CYM pretreatment resulted in a significant decrease in the number of rolling (100, 200 mg/kg and in the number of adherent leukocytes (100, 200, 400 mg/kg to the perivascular tissue. The macrophage phagocytic index was increased significantly in concentrations of CYM (3, 10, 30 µg/ml. Treatment with CYM (10, 90 µg/ml also reduced TNF- levels but did not alter IL-10 levels in fMLP-stimulated neutrophils. In conclusion, CYM may be considered as a potential agent for treatment inflammatory injury, however, further studies are necessary to elucidate the anti-inflammatory mechanism.Industrial relevance. The CYM is a secondary metabolite, belongs to the class of monoterpene and is found in essential oils from plants, food and in several spices. It is an important intermediate used in pharmaceutical, flavor and aroma industries and for the production of fungicides. The investigation of the anti-inflammatory activity of this compound may be useful to development of new drug anti-inflammatory, on a commercial scale.Keywords. p-cymene; chemotaxis; in vivo microcirculation; phagocytosis; anti-inflammatory.

  16. Frustrated phagocytosis on micro-patterned immune complexes to characterize lysosome movements in live macrophages.

    Directory of Open Access Journals (Sweden)

    Arnaud M. Labrousse

    2011-10-01

    Full Text Available Lysosome mobilization is a key cellular process in phagocytes for bactericidal activities and trans-matrix migration. The molecular mechanisms that regulate lysosome mobilization are still poorly known. Lysosomes are hard to track as they move towards phagosomes throughout the cell volume. In order to anticipate cell regions where lysosomes are recruited to, human and RAW264.7 macrophages were seeded on surfaces that were micro-patterned with immune complexes (ICs as 4 µm-side squares. Distances between IC patterns were adapted to optimize cell spreading in order to constrain lysosome movements mostly in 2 dimensions. Fc receptors triggered local frustrated phagocytosis, frustrated phagosomes appeared as rings of F-actin dots around the IC patterns as early as 5 minutes after cells made contact with the substratum. Frustrated phagosomes recruited actin-associated proteins (vinculin, paxillin and gelsolin. The fusion of lysosomes with frustrated phagosomes was shown by the release of beta-hexosaminidase and the recruitment of Lamp-1 to frustrated phagosomes. Lysosomes of RAW264.7 macrophages were labeled with cathepsinD-mCherry to visualize their movements towards frustrated phagosomes. Lysosomes saltatory movements were markedly slowed down compared to cells layered on non-opsonized patterns. In addition, the linearity of the trajectories and the frequency and duration of contacts of lysosomes with frustrated phagosomes were measured.¬¬¬¬¬¬¬¬ Using PP2 we showed that instant velocity, pauses and frequency of lysosome/phagosome contacts were at least in part dependent on Src tyrosine kinases. This experimental set-up is the first step towards deciphering molecular mechanisms which are involved in lysosome movements in the cytoplasm (directionality, docking and fusion using RNA interference, pharmacological inhibition or mutant expression.

  17. Lipopolysaccharide induces multinuclear cell from RAW264.7 line with increased phagocytosis activity

    Energy Technology Data Exchange (ETDEWEB)

    Nakanishi-Matsui, Mayumi, E-mail: nakanim@iwate-med.ac.jp [Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Futai Special Laboratory, Yahaba, Iwate 028-3694 (Japan); Yano, Shio; Matsumoto, Naomi; Futai, Masamitsu [Department of Biochemistry, Faculty of Pharmaceutical Sciences, Iwate Medical University, Futai Special Laboratory, Yahaba, Iwate 028-3694 (Japan)

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer LPS induces multinuclear cells from murine macrophage-derived RAW264.7 cells. Black-Right-Pointing-Pointer The multinuclear cells are formed through cell-cell fusion in the presence of Ca{sup 2+}. Black-Right-Pointing-Pointer The multinuclear cells do not express osteoclast-specific enzymes. Black-Right-Pointing-Pointer They internalized more and larger beads than mononuclear cells and osteoclasts. -- Abstract: Lipopolysaccharide (LPS), an outer membrane component of Gram-negative bacteria, induces strong proinflammatory responses, including the release of cytokines and nitric oxide from macrophage. In this study, we found that a murine macrophage-derived line, RAW264.7, became multinuclear through cell-cell fusion after incubation with highly purified LPS or synthetic lipid A in the presence of Ca{sup 2+}. The same cell line is known to differentiate into multinuclear osteoclast, which expresses a specific proton pumping ATPase together with osteoclast markers on stimulation by the extracellular domain of receptor activator of nuclear factor {kappa}B ligand (Toyomura, T., Murata, Y., Yamamoto, A., Oka, T., Sun-Wada, G.-H., Wada, Y. and Futai, M., 2003). The LPS-induced multinuclear cells did not express osteoclast-specific enzymes including tartrate-resistant acid phosphatase and cathepsin K. During multinuclear cell formation, the cells internalized more and larger polystyrene beads (diameter 6-15 {mu}m) than mononuclear cells and osteoclasts. The internalized beads were located in lysosome-marker positive organelles, which were probably phagolysosomes. The LPS-induced multinuclear cell could be a good model system to study phagocytosis of large foreign bodies.

  18. Correlation between the circadian rhythm of melatonin, phagocytosis, and superoxide anion levels in ring dove heterophils.

    Science.gov (United States)

    Rodríguez, A B; Marchena, J M; Nogales, G; Durán, J; Barriga, C

    1999-01-01

    A functional role for melatonin is its relationship to circadian timing mechanisms. In addition, there has recently been assumed to be a functional connection between the pineal gland and the immune system in mammals and birds, with some findings showing melatonin to be a free radical scavenger and general antioxidant. The present study investigates the possible relationship between the circadian rhythm of melatonin and the ingestion capacity as well as superoxide anion levels of ring dove (Streptopelia risoria) heterophils. In birds, heterophils, with their ability to ingest and kill different antigens, play a central role in the host defence mechanism. All determinations were made during 24 hr periods at 2 hr intervals. Radioimmunoassay showed an increase of melatonin serum levels during the dark period (from 20:00 to 07:00 hr) with a maximum at 04:00 hr, and a significant decline during the hours of light with a minimum at 16:00 hr. Similarly, the phagocytic index was enhanced during the night, with the maximum at approximately 04:00 hr and the minimum at approximately 18:00 hr. The same was the case in relation to phagocytic percentage. However, the superoxide anion levels were lower during darkness (minimum at 04:00 hr) and higher during the light period (maximum at 14:00 hr). In conclusion, our findings show that one pineal-mediated effect on the immune system may be a direct action of melatonin on phagocytosis and the phagocytic biochemical process, and that this neurohormone might act as an antioxidant.

  19. Antimicrobial seafood packaging: a review.

    Science.gov (United States)

    Singh, Suman; Ho Lee, Myung; Park, Lnsik; Shin, Yangjai; Lee, Youn Suk

    2016-06-01

    Microorganisms are the major cause of spoilage in most seafood products; however, only few microbes, called the specific spoilage organisms (SSOs), contribute to the offensive off-flavors associated with seafood spoilage. In food, microbial degradation manifests itself as spoilage, or changes in the sensory properties of a food product, rendering it unsuitable for human consumption. The use of antimicrobial substances can control the general microflora as well as specific microorganisms related to spoilage to provide products with higher safety and better quality. Many antimicrobial compounds have been evaluated in film structures for use in seafood, especially organic acids and their salts, enzymes, bacteriocins; some studies have considered inorganic compounds such as AgSiO2, zinc oxide, silver zeolite, and titanium oxide. The characteristics of some organic antimicrobial packaging systems for seafood and their antimicrobial efficiency in film structures are reviewed in this article.

  20. Serological Characterization and Antimicrobial Susceptibility ...

    African Journals Online (AJOL)

    300L Coordinator

    identified and antibiotic susceptibility test was performed using standard procedures. The total .... serotypes and their antimicrobial resistivity patterns from patients ..... the best of our knowledge). ... Testing of Bacterial Pathogens of Public.

  1. [Therapeutic drug monitoring of antimicrobials

    NARCIS (Netherlands)

    Mouton, J.W.; Aarnoutse, R.E.

    2014-01-01

    The importance of dose adjustments of antimicrobials based on measured concentrations in an individual ('therapeutic drug monitoring', TDM) is increasingly recognized. There are several reasons for this. First, there is a better understanding of the relationships between doses administered,

  2. The safety of antimicrobial drugs

    OpenAIRE

    Ćupić Vitomir; Jezdimirović Milanka; Dobrić Silva; Ivanović Saša; Ćupić-Miladinović Dejana

    2016-01-01

    The discovery and introduction of antimicrobial drugs in clinical practice has been recorded as one of the greatest achievements in the history of medicine. The application of these drugs, made a big, almost revolutionary upheaval in treatment of many infectious diseases. Its significance for the humanity lies in the fact that hundreds of thousands of people, until then condemned to a certain death, has been saved now. However, it was shown that antimicrobi...

  3. Antimicrobials for bacterial bioterrorism agents.

    Science.gov (United States)

    Sarkar-Tyson, Mitali; Atkins, Helen S

    2011-06-01

    The limitations of current antimicrobials for highly virulent pathogens considered as potential bioterrorism agents drives the requirement for new antimicrobials that are suitable for use in populations in the event of a deliberate release. Strategies targeting bacterial virulence offer the potential for new countermeasures to combat bacterial bioterrorism agents, including those active against a broad spectrum of pathogens. Although early in the development of antivirulence approaches, inhibitors of bacterial type III secretion systems and cell division mechanisms show promise for the future.

  4. Antimicrobial constituents of Foeniculum vulgare.

    Science.gov (United States)

    Kwon, Yong Soo; Choi, Won Gyu; Kim, Won Jun; Kim, Woo Kyung; Kim, Myong Jo; Kang, Won Hee; Kim, Chang Min

    2002-04-01

    A phenyl propanoid derivative, dillapional(1) was found to be a antimicrobial principle of the stems of Foeniculum vulgare (Umbelliferae) with MIC values of 125, 250 and 125/ against Bacillus subtilis, Aspergillus niger and Cladosporium cladosporioides, respectively. A coumarin derivative, scopoletin(2) was also isolated as marginally antimicrobial agent along with inactive compounds, dillapiol(3), bergapten(4), imperatorin(5) and psolaren(6) from this plant. The isolates 1-6 were not active against the Escherichia coli.

  5. Specialized Pro-Resolving Mediators from Omega-3 Fatty Acids Improve Amyloid-β Phagocytosis and Regulate Inflammation in Patients with Minor Cognitive Impairment.

    Science.gov (United States)

    Fiala, Milan; Terrando, Niccolo; Dalli, Jesmond

    2015-01-01

    In this review we discuss the immunopathology of Alzheimer's disease (AD) and recent advances in the prevention of minor cognitive impairment (MCI) by nutritional supplementation with omega-3 fatty acids. Defective phagocytosis of amyloid-β (Aβ) and abnormal inflammatory activation of peripheral blood mononuclear cells (PBMCs) are the two key immune pathologies of MCI and AD patients. The phagocytosis of Aβ by PBMCs of MCI and AD patients is universally defective and the inflammatory gene transcription is heterogeneously deregulated in comparison to normal subjects. Recent studies have discovered a cornucopia of beneficial anti-inflammatory and pro-resolving effects of the specialized proresolving mediators (SPMs) resolvins, protectins, maresins, and their metabolic precursors. Resolvin D1 and other mediators switch macrophages from an inflammatory to a tissue protective/pro-resolving phenotype and increase phagocytosis of Aβ. In a recent study of AD and MCI patients, nutritional supplementation by omega-3 fatty acids individually increased resolvin D1, improved Aβ phagocytosis, and regulated inflammatory genes toward a physiological state, but only in MCI patients. Our studies are beginning to dissect positive factors (adherence to Mediterranean diet with omega-3 and exercise) and negative factors (high fat diet, infections, cancer, and surgeries) in each patient. The in vitro and in vivo effects of omega-3 fatty acids and SPMs suggest that defective phagocytosis and chronic inflammation are related to defective production and/or defective signaling by SPMs in immune cells.

  6. Garenoxacin-induced increase of CD11b expression on human polymorphonuclear neutrophils does not affect phagocytosis and killing of Staphylococcus aureus.

    Science.gov (United States)

    Grüger, Thomas; Reiners, Ana-Lena; Schnitzler, Norbert; Brandenburg, Kerstin; Zündorf, Josef

    2011-04-01

    Garenoxacin is considered to be the most active quinolone against Staphylococcus aureus. Quinolones are believed to alter the function of human polymorphonuclear leukocytes (PMN) and garenoxacin is known to be the only quinolone which alters the expression of the beta-chain (CD11b) of the complement receptor 3 (CR3) which is known to be important in the phagocytosis of S. aureus by PMN. Therefore, the effect of this altered CD11b expression on phagocytosis, oxidative burst, and killing of S. aureus was addressed and compared with that of standard quinolones. Phagocytosis and oxidative burst were determined by flow cytometry, and killing was measured by a colony-count method. Garenoxacin at therapeutic concentrations affected neither phagocytosis nor killing of Staphylococcus aureus NMS54. At supratherapeutic concentrations (1,500 mg/l) garenoxacin reduced and delayed phagocytosis like all other quinolones tested except norfloxacin. This decrease seems to be a result of inhibition of the oxidative burst of PMN and reduced CD11b expression at this supratherapeutic concentration. In conclusion, the alteration of CD11b expression of PMN caused by garenoxacin at 0.5, 5.0, and 100.0 mg/l is not considered to hamper the function of these first-line-defense phagocytes.

  7. MerTK Does Not Mediate Phagocytosis of Staphylococcus aureus but Attenuates Inflammation Induced by Staphylococcal Lipoteichoic Acid Through Blocking NF-κB Activation.

    Science.gov (United States)

    Zhang, Bing; Wu, Huimei; Fang, Lei; Ding, Peishan; Xu, Ke; Yang, Qingbin; Liu, Rongyu

    2017-05-20

    Mer receptor tyrosine kinase (MerTK) expressed in macrophages is essential for phagocytosis of apoptotic cells. Here, we investigate whether MerTK is involved in the phagocytosis of Staphylococcus aureus (S. aureus) and regulation of staphylococcal lipoteichoic acid (LTA)-induced inflammatory response in macrophages. We found that stimulating RAW264.7 macrophages with S. aureus activated multiple signaling pathways including toll-like receptor 2 (TLR2), scavenger receptor A (SR-A), and MerTK. Meanwhile, S. aureus stimulation also induced activation of proteins focal adhesion kinase (FAK) and Rac1, which are related to phagocytosis. Pretreatment with a specific Mer-blocking antibody significantly inhibited S. aureus-induced phosphorylation of MerTK, while it had no effect on S. aureus-induced activation of FAK and Rac1. Moreover, by confocal laser microscope, we observed that the antibody blockade of MerTK had little impact on the phagocytosis of S. aureus by RAW264.7 macrophages. Additionally, pretreatment with this antibody further promoted LTA-induced phosphorylation of nuclear factor κB (NF-κB) p65 subunit and production of pro-inflammatory cytokines, such as TNF-α, IL-6, IL-1β, and macrophage inflammatory protein-2 (MIP-2). Collectively, these results suggest that MerTK does not play an essential role in the phagocytosis of S. aureus but attenuates inflammation induced by staphylococcal LTA through blocking NF-κB activation.

  8. Regulator of G-Protein Signalling-14 (RGS14 Regulates the Activation of αMβ2 Integrin during Phagocytosis.

    Directory of Open Access Journals (Sweden)

    Jenson Lim

    Full Text Available Integrin-mediated phagocytosis, an important physiological activity undertaken by professional phagocytes, requires bidirectional signalling to/from αMβ2 integrin and involves Rap1 and Rho GTPases. The action of Rap1 and the cytoskeletal protein talin in activating αMβ2 integrins, in a RIAM-independent manner, has been previously shown to be critical during phagocytosis in mammalian phagocytes. However, the events downstream of Rap1 are not clearly understood. Our data demonstrate that one potential Rap1 effector, Regulator of G-Protein Signalling-14 (RGS14, is involved in activating αMβ2. Exogenous expression of RGS14 in COS-7 cells expressing αMβ2 results in increased binding of C3bi-opsonised sheep red blood cells. Consistent with this, knock-down of RGS14 in J774.A1 macrophages results in decreased association with C3bi-opsonised sheep red blood cells. Regulation of αMβ2 function occurs through the R333 residue of the RGS14 Ras/Rap binding domain (RBD and the F754 residue of β2, residues previously shown to be involved in binding of H-Ras and talin1 head binding prior to αMβ2 activation, respectively. Surprisingly, overexpression of talin2 or RAPL had no effect on αMβ2 regulation. Our results establish for the first time a role for RGS14 in the mechanism of Rap1/talin1 activation of αMβ2 during phagocytosis.

  9. Effects of early-life lead exposure on oxidative status and phagocytosis activity in great tits (Parus major).

    Science.gov (United States)

    Rainio, Miia J; Eeva, Tapio; Lilley, Thomas; Stauffer, Janina; Ruuskanen, Suvi

    2015-01-01

    Lead is a highly poisonous metal with a very long half-life, distributing throughout the body in blood and accumulating primarily in bones and kidney. We studied the short and long-term effects of early-life lead exposure on antioxidant defense and phagocytosis activity in a small passerine bird, the great tit (Parus major) by manipulating dietary lead levels of the nestlings. We had three experimental groups, exposed to environmentally relevant lead concentrations; high (4 μg/g body mass), low (1 μg/g body mass) and control (0 μg/g body mass) group. As a comparison, a great tit population breeding in the vicinity of a metal smelter was included to the experimental set-up. We measured glutathione, the ratio of reduced and oxidized glutathione, and the antioxidant enzymes: glutathione peroxidase, glutathione-S-transferase, catalase and superoxide dismutase together with protein carbonylation and phagocytosis activity to study the effects of lead on the oxidative status and immune function of birds. We found differences in enzyme activities between the study groups, but in most cases the smelter group differed from the other groups. Despite the differences observed in antioxidant enzymes, our results indicate only minor short-term effects of lead exposure on oxidative status, since either glutathione ratio or protein carbonylation were not affected by lead. Phagocytosis activity was not linked to higher lead concentrations either. Interestingly, protein carbonylation was positively associated with enzyme activities and glutathione level. Our results did not show major long-term effects of lead on the oxidative status of great tits.

  10. EhVps32 Is a Vacuole-Associated Protein Involved in Pinocytosis and Phagocytosis of Entamoeaba histolytica.

    Directory of Open Access Journals (Sweden)

    Yunuen Avalos-Padilla

    2015-07-01

    Full Text Available Here, we investigated the role of EhVps32 protein (a member of the endosomal-sorting complex required for transport in endocytosis of Entamoeba histolytica, a professional phagocyte. Confocal microscopy, TEM and cell fractionation revealed EhVps32 in cytoplasmic vesicles and also located adjacent to the plasma membrane. Between 5 to 30 min of phagocytosis, EhVps32 was detected on some erythrocytes-containing phagosomes of acidic nature, and at 60 min it returned to cytoplasmic vesicles and also appeared adjacent to the plasma membrane. TEM images revealed it in membranous structures in the vicinity of ingested erythrocytes. EhVps32, EhADH (an ALIX family member, Gal/GalNac lectin and actin co-localized in the phagocytic cup and in some erythrocytes-containing phagosomes, but EhVps32 was scarcely detected in late phagosomes. During dextran uptake, EhVps32, EhADH and Gal/GalNac lectin, but not actin, co-localized in pinosomes. EhVps32 recombinant protein formed oligomers composed by rings and filaments. Antibodies against EhVps32 monomers stained cytoplasmic vesicles but not erythrocytes-containing phagosomes, suggesting that in vivo oligomers are formed on phagosome membranes. The involvement of EhVps32 in phagocytosis was further study in pNeoEhvps32-HA-transfected trophozoites, which augmented almost twice their rate of erythrophagocytosis as well as the membranous concentric arrays built by filaments, spirals and tunnel-like structures. Some of these structures apparently connected phagosomes with the phagocytic cup. In concordance, the EhVps32-silenced G3 trophozoites ingested 80% less erythrocytes than the G3 strain. Our results suggest that EhVps32 participates in E. histolytica phagocytosis and pinocytosis. It forms oligomers on erythrocytes-containing phagosomes, probably as a part of the scission machinery involved in membrane invagination and intraluminal vesicles formation.

  11. EhVps32 Is a Vacuole-Associated Protein Involved in Pinocytosis and Phagocytosis of Entamoeaba histolytica.

    Science.gov (United States)

    Avalos-Padilla, Yunuen; Betanzos, Abigail; Javier-Reyna, Rosario; García-Rivera, Guillermina; Chávez-Munguía, Bibiana; Lagunes-Guillén, Anel; Ortega, Jaime; Orozco, Esther

    2015-07-01

    Here, we investigated the role of EhVps32 protein (a member of the endosomal-sorting complex required for transport) in endocytosis of Entamoeba histolytica, a professional phagocyte. Confocal microscopy, TEM and cell fractionation revealed EhVps32 in cytoplasmic vesicles and also located adjacent to the plasma membrane. Between 5 to 30 min of phagocytosis, EhVps32 was detected on some erythrocytes-containing phagosomes of acidic nature, and at 60 min it returned to cytoplasmic vesicles and also appeared adjacent to the plasma membrane. TEM images revealed it in membranous structures in the vicinity of ingested erythrocytes. EhVps32, EhADH (an ALIX family member), Gal/GalNac lectin and actin co-localized in the phagocytic cup and in some erythrocytes-containing phagosomes, but EhVps32 was scarcely detected in late phagosomes. During dextran uptake, EhVps32, EhADH and Gal/GalNac lectin, but not actin, co-localized in pinosomes. EhVps32 recombinant protein formed oligomers composed by rings and filaments. Antibodies against EhVps32 monomers stained cytoplasmic vesicles but not erythrocytes-containing phagosomes, suggesting that in vivo oligomers are formed on phagosome membranes. The involvement of EhVps32 in phagocytosis was further study in pNeoEhvps32-HA-transfected trophozoites, which augmented almost twice their rate of erythrophagocytosis as well as the membranous concentric arrays built by filaments, spirals and tunnel-like structures. Some of these structures apparently connected phagosomes with the phagocytic cup. In concordance, the EhVps32-silenced G3 trophozoites ingested 80% less erythrocytes than the G3 strain. Our results suggest that EhVps32 participates in E. histolytica phagocytosis and pinocytosis. It forms oligomers on erythrocytes-containing phagosomes, probably as a part of the scission machinery involved in membrane invagination and intraluminal vesicles formation.

  12. Immunomodulatory effects of selected Malaysian plants on the CD18/11a expression and phagocytosis activities of leukocytes

    Institute of Scientific and Technical Information of China (English)

    Nurul; Hikmah; Harun; Abdi; Wira; Septama; Ibrahim; Jantan

    2015-01-01

    Objective:To investigate the effects of 20 methanolic extracts from Malaysian selected plants on CD18/11 a expression and phagocytosis activity of leukocytes using flow cytometry analysis.Methods:The effects of methanolic extracts on CD18/11 a expression and phagocytosis of leukocytes were measured by labelling the cells with CD18-fluorescein isolhiocyanaie and ingestion labelled with Escherichia coli-fluorescein isothiocyanate and then analyzed using flow cytometer.Results:About 12 out of 20 methanolic extracts of selected Malaysian medicinal plants significantly(P≤0.05) inhibited the CD18/1 la expression of leukocytes at both concentrations of 6.25 μg/mL and 100 μg/mL in dose dependent manner.The most active inhibitory was shown in Citrus aurantifolia(Christm.) Swingle and Alpinia galangal(L.) Willd.at dosage 100ug/mL.Moreover,the Orthosiphon aristatus(Blume) Miq(O.aristatus).showed the highest stimulatory activity at the concentration of 100 μg/mL.Other than that,four plant extracts significantly(P<0.05) rose the phagocytosis activities of leukocytes in dose dependent manner.However,Annona muricata L.and O.aristatus showed the highest stimulated activities at the 100 pg/mL concentration.Conclusions:The results suggest that methanolic extracts of Cirrus aurantifolia.Alpinia gaiangal,O.aristatus and Annona muricata are able to modulate innate immune system and can potentially be recognized as therapeutic agents for modulating immune system.

  13. Type I (CD64) and type II (CD32) Fc gamma receptor-mediated phagocytosis by human blood dendritic cells.

    Science.gov (United States)

    Fanger, N A; Wardwell, K; Shen, L; Tedder, T F; Guyre, P M

    1996-07-15

    Three classes of Fc receptors for IgG, Fc gamma RI (CD64), Fc gamma RII (CD32), and Fc gamma RIII (CD16), are expressed on blood leukocytes. Although Fc gamma R are important phagocytic receptors on phagocytes, most reports suggest that dendritic cells lack Fc gamma R-mediated phagocytosis and express significant levels of only CD32. We now report that phagocytically active forms of both CD64 and CD32 are expressed significantly on at least one subset of human blood dendritic cells. Countercurrent elutriation and magnetic bead selection were used to rapidly enrich subsets of blood dendritic cells (CD33brightCD14-HLA-DRbrightCD83-) and monocytes (CD33brightCD14brightHLA-DRdimCD83-). Upon culture for 2 days, dendritic cells became CD83-positive and markedly increased HLA-DR expression, whereas monocytes did not express CD83 and exhibited reduced levels of HLA-DR. Constitutive CD64 expression was identified on this circulating dendritic cell population, but at a lower level than on monocytes. CD64 expression by dendritic cells and monocytes did not decrease during 2 days in culture, and was up-regulated on both cell types following incubation with IFN-gamma. Freshly isolated blood dendritic cells performed CD64- and CD32-mediated phagocytosis, although at a lower level than monocytes. Dendritic cells generated by culture of adherent mononuclear cells in granulocyte-macrophage CSF and IL-4 also up-regulated CD64 following IFN-gamma stimulation, and mediated CD64-dependent phagocytosis. These results indicate that both CD64 and CD32 expressed on blood dendritic cells may play a role in uptake of foreign particles and macromolecules through a phagocytic mechanism before trafficking to T cell-reactive areas.

  14. Simultaneous determination of phagocytosis of Plasmodium falciparum-parasitized and non-parasitized red blood cells by flow cytometry

    Directory of Open Access Journals (Sweden)

    Gallo Valentina

    2012-12-01

    Full Text Available Abstract Background Severe falciparum malaria anaemia (SMA is a frequent cause of mortality in children and pregnant women. The most important determinant of SMA appears to be the loss of non-parasitized red blood cells (np-RBCs in excess of loss of parasitized (p- RBCs at schizogony. Based on data from acute SMA where excretion of haemoglobin in urine and increased plasma haemoglobin represented respectively less than 1% and 0.5% of total Hb loss, phagocytosis appears to be the predominant mechanism of removal of np- and p-RBC. Estimates indicate that np-RBCs are cleared in approximately 10-fold excess compared to p-RBCs. An even larger removal of np-RBCs has been described in vivax malaria anaemia. Estimates were based on two single studies both performed on neurosyphilitic patients who underwent malaria therapy. As the share of np-RBC removal is likely to vary between wide limits, it is important to assess the contribution of both np- and p-RBC populations to overall RBC loss, and disclose the mechanism of such variability. As available methods do not discriminate between the removal of np- vs p-RBCs, the purpose of this study was to set up a system allowing the simultaneous determination of phagocytosis of p- and np-RBC in the same sample. Methods and Results Phagocytosis of p- and np-RBCs was quantified in the same sample using double-labelled target cells and the human phagocytic cell-line THP-1, pre-activated by TNF and IFNγ to enhance their phagocytic activity. Target RBCs were double-labelled with fluorescent carboxyfluorescein-succinimidyl ester (CF-SE and the DNA label ethidium bromide (EB. EB, a DNA label, allowed to discriminate p-RBCs that contain parasitic DNA from the np-RBCs devoid of DNA. FACS analysis of THP-1 cells fed with double-labelled RBCs showed that p- and np-RBCs were phagocytosed in different proportions in relation to parasitaemia. Conclusions The assay allowed the analysis of phagocytosis rapidly and with low

  15. Immune functions in beluga whales (Delphinapterus leucas): evaluation of phagocytosis and respiratory burst with peripheral blood leukocytes using flow cytometry.

    Science.gov (United States)

    de Guise, S; Flipo, D; Boehm, J R; Martineau, D; Béland, P; Fournier, M

    1995-08-01

    Flow cytometric assays using peripheral blood were developed to study phagocytosis and respiratory burst, the two major functions of neutrophils and among the most important non-specific defense mechanisms, in beluga whales. The use of flow cytometry avoids the problems associated with the isolation and purification of different cell types, and allows the measurement of a large number of cells (10,000) in a very short period of time. The methods described will be used to compare these functions in blood samples from highly contaminated beluga whales from the St. Lawrence and from relatively clean arctic beluga whales.

  16. Antimicrobial stewardship in a Gastroenterology Department: Impact on antimicrobial consumption, antimicrobial resistance and clinical outcome.

    Science.gov (United States)

    Bedini, Andrea; De Maria, Nicola; Del Buono, Mariagrazia; Bianchini, Marcello; Mancini, Mauro; Binda, Cecilia; Brasacchio, Andrea; Orlando, Gabriella; Franceschini, Erica; Meschiari, Marianna; Sartini, Alessandro; Zona, Stefano; Paioli, Serena; Villa, Erica; Gyssens, Inge C; Mussini, Cristina

    2016-10-01

    A major cause of the increase in antimicrobial resistance is the inappropriate use of antimicrobials. To evaluate the impact on antimicrobial consumption and clinical outcome of an antimicrobial stewardship program in an Italian Gastroenterology Department. Between October 2014 and September 2015 (period B), a specialist in infectious diseases (ID) controlled all antimicrobial prescriptions and decided about the therapy in agreement with gastroenterologists. The defined daily doses of antimicrobials (DDDs), incidence of MDR-infections, mean length of stay and overall in-hospital mortality rate were compared with those of the same period in the previous 12-months (period A). During period B, the ID specialist performed 304 consultations: antimicrobials were continued in 44.4% of the cases, discontinued in 13.8%, not recommended in 12.1%, de-escalated 9.9%, escalated in 7.9%, and started in 4.0%. Comparing the 2 periods, we observed a decreased of antibiotics consumption (from 109.81 to 78.45 DDDs/100 patient-days, p=0.0005), antifungals (from 41.28 to 24.75 DDDs/100pd, p=0.0004), carbapenems (from 15.99 to 6.80 DDDsx100pd, p=0.0032), quinolones (from 35.79 to 17.82 DDDsx100pd, p=0.0079). No differences were observed in incidence of MDR-infections, length of hospital stay (LOS), and mortality rate. ASP program had a positive impact on reducing the consumption of antimicrobials, without an increase in LOS and mortality. Copyright © 2016 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

  17. Antimicrobial peptides in crustaceans

    Directory of Open Access Journals (Sweden)

    RD Rosa

    2010-11-01

    Full Text Available Crustaceans are a large and diverse invertebrate animal group that mounts a complex and efficient innate immune response against a variety of microorganisms. The crustacean immune system is primarily related to cellular responses and the production and release of important immune effectors into the hemolymph. Antimicrobial proteins and/or peptides (AMPs are key components of innate immunity and are widespread in nature, from bacteria to vertebrate animals. In crustaceans, 15 distinct AMP families are currently recognized, although the great majority (14 families comes from members of the order Decapoda. Crustacean AMPs are generally cationic, gene-encoded molecules that are mainly produced by circulating immune-competent cells (hemocytes or are derived from unrelated proteins primarily involved in other biological functions. In this review, we tentatively classified the crustacean AMPs into four main groups based on their amino acid composition, structural features and multi-functionality. We also attempted to summarize the current knowledge on their implication both in an efficient response to microbial infections and in crustacean survival.

  18. Antimicrobial activity of flavonoids.

    Science.gov (United States)

    Cushnie, T P Tim; Lamb, Andrew J

    2005-11-01

    Flavonoids are ubiquitous in photosynthesising cells and are commonly found in fruit, vegetables, nuts, seeds, stems, flowers, tea, wine, propolis and honey. For centuries, preparations containing these compounds as the principal physiologically active constituents have been used to treat human diseases. Increasingly, this class of natural products is becoming the subject of anti-infective research, and many groups have isolated and identified the structures of flavonoids possessing antifungal, antiviral and antibacterial activity. Moreover, several groups have demonstrated synergy between active flavonoids as well as between flavonoids and existing chemotherapeutics. Reports of activity in the field of antibacterial flavonoid research are widely conflicting, probably owing to inter- and intra-assay variation in susceptibility testing. However, several high-quality investigations have examined the relationship between flavonoid structure and antibacterial activity and these are in close agreement. In addition, numerous research groups have sought to elucidate the antibacterial mechanisms of action of selected flavonoids. The activity of quercetin, for example, has been at least partially attributed to inhibition of DNA gyrase. It has also been proposed that sophoraflavone G and (-)-epigallocatechin gallate inhibit cytoplasmic membrane function, and that licochalcones A and C inhibit energy metabolism. Other flavonoids whose mechanisms of action have been investigated include robinetin, myricetin, apigenin, rutin, galangin, 2,4,2'-trihydroxy-5'-methylchalcone and lonchocarpol A. These compounds represent novel leads, and future studies may allow the development of a pharmacologically acceptable antimicrobial agent or class of agents.

  19. Antimicrobial peptides in annelids

    Directory of Open Access Journals (Sweden)

    A Tasiemski

    2008-06-01

    Full Text Available Gene encoded antimicrobial peptides (AMPs are widely distributed among living organisms including plants, invertebrates and vertebrates. They constitute important effectors of the innate immune response by exerting multiple roles as mediators of inflammation with impact on epithelial and inflammatory cells influencing diverse processes such as cytokine release, cell proliferation, angiogenesis, wound healing, chemotaxis and immune induction. In invertebrates, most of the data describe the characterization and/or the function of AMPs in the numerically and economically most representative group which are arthropods. Annelids are among the first coelomates and are therefore of special phylogenetic interest. Compared to other invertebrate groups, data on annelid’s immunity reveal heavier emphasis on the cellular than on the humoral response suggesting that immune defense of annelids seems to be principally developed as cellular immunity.This paper gives an overview of the variety of AMPs identified in the three classes of annelids, i.e. polychaetes, oligochaetes and achaetes. Their functions, when they have been studied, in the humoral or cellular response of annelids are also mentioned.

  20. Epithelial Antimicrobial Peptides: Guardian of the Oral Cavity

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    Mayank Hans

    2014-01-01

    Full Text Available Gingival epithelium provides first line of defence from the microorganisms present in dental plaque. It not only provides a mechanical barrier but also has an active immune function too. Gingival epithelial cells participate in innate immunity by producing a range of antimicrobial peptides to protect the host against oral pathogens. These epithelial antimicrobial peptides (EAPs include the β-defensin family, cathelicidin (LL-37, calprotectin, and adrenomedullin. While some are constitutively expressed in gingival epithelial cells, others are induced upon exposure to microbial insults. It is likely that these EAPs have a role in determining the initiation and progression of oral diseases. EAPs are broad spectrum antimicrobials with a different but overlapping range of activity. Apart from antimicrobial activity, they participate in several other crucial roles in host tissues. Some of these, for instance, β-defensins, are chemotactic to immune cells. Others, such as calprotectin are important for wound healing and cell proliferation. Adrenomedullin, a multifunctional peptide, has its biological action in a wide range of tissues. Not only is it a potent vasodilator but also it has several endocrine effects. Knowing in detail the various bioactions of these EAPs may provide us with useful information regarding their utility as therapeutic agents.

  1. Editorial of the Special Issue Antimicrobial Polymers

    Directory of Open Access Journals (Sweden)

    Iolanda Francolini

    2013-09-01

    Full Text Available The special issue “Antimicrobial Polymers” includes research and review papers concerning the recent advances on preparation of antimicrobial polymers and their relevance to industrial settings and biomedical field. Antimicrobial polymers have recently emerged as promising candidates to fight microbial contamination onto surfaces thanks to their interesting properties. In this special issue, the main strategies pursued for developing antimicrobial polymers, including polymer impregnation with antimicrobial agents or synthesis of polymers bearing antimicrobial moieties, were discussed. The future application of these polymers either in industrial or healthcare settings could result in an extremely positive impact not only at the economic level but also for the improvement of quality of life.

  2. Antimicrobial resistance in bacteria from horses: Epidemiology of antimicrobial resistance.

    Science.gov (United States)

    Maddox, T W; Clegg, P D; Williams, N J; Pinchbeck, G L

    2015-11-01

    Antimicrobial resistance poses a significant threat to the continued successful use of antimicrobial agents for the treatment of bacterial infections. While the epidemiology of antimicrobial resistance in bacteria from man has been studied extensively, less work has been undertaken in companion animals, particularly horses. Methicillin-resistant Staphylococcus aureus has been identified as a cause of infections, with a low prevalence of nasal carriage by horses in the community but higher for hospitalised horses. Molecular characterisation has shown methicillin-resistant Staphylococcus aureus strains either to be predominantly of types associated with horses or of sequence type ST398. Antimicrobial-resistant Escherichia coli (including multidrug-resistant and extended spectrum β-lactamase-producing isolates) have caused infections and been documented in faecal carriage by horses, with many significant resistance mechanisms identified. More sporadic reports and molecular characterisation exist for resistance in other bacteria such as enterococci, Salmonella, Acinetobacter and Pseudomonas species. Limited work has been undertaken evaluating risk factors and much of the epidemiology of antimicrobial resistance in bacteria from horses remains to be determined.

  3. How to educate prescribers in antimicrobial stewardship practices

    NARCIS (Netherlands)

    Pulcini, C.; Gyssens, I.C.J.

    2013-01-01

    Widespread antimicrobial use has compromised its value, leading to a crisis of antimicrobial resistance. A major cause of misuse is insufficient knowledge of prescribing of antimicrobials in many categories of professionals. An important principle of antimicrobial stewardship is avoiding selection

  4. Monoacylglycerol lipase promotes Fcγ receptor-mediated phagocytosis in microglia but does not regulate LPS-induced upregulation of inflammatory cytokines.

    Science.gov (United States)

    Kouchi, Zen

    2015-08-21

    Monoacylglycerol lipase (MAGL) is important for neuroinflammation. However, the regulatory mechanisms underlying its expression and function remain unknown. Lipopolysaccharide (LPS) treatment post-translationally upregulated MAGL expression, whereas it downregulated MAGL transcription through a Stat6-mediated mechanism in microglia. Neither MAGL knockdown nor JZL-184, a selective MAGL inhibitor, suppressed LPS-induced upregulation of inflammatory cytokines in microglia. Moreover, exogenous expression of MAGL in BV-2 microglial cell line, which lacks endogenous MAGL, did not promote the induction of inflammatory cytokines by LPS treatment. Interestingly, MAGL knockdown reduced Fcγ receptor-mediated phagocytosis in primary microglia, and introduction of MAGL into the BV-2 cells increased Fcγ receptor-mediated phagocytosis. Collectively, these results suggest that MAGL regulates phagocytosis, but not LPS-mediated cytokine induction in microglia.

  5. Diverse regulation of retinal pigment epithelium phagocytosis of photoreceptor outer segments by calcium-independent phospholipase A₂, group VIA and secretory phospholipase A₂, group IB

    DEFF Research Database (Denmark)

    Zhan, Chen; Wang, Jinmei; Kolko, Miriam

    2012-01-01

    the role of iPLA(2)-VIA in RPE phagocytosis of POS, experiments with iPLA(2)-VIA vector transfection, iPLA(2)-VIA(-/-) knockout (KO) mice, and iPLA(2)-VIA inhibition by bromoenol lactone (BEL) were done. Exogenous addition of sPLA(2)-IB was used to investigate the role of sPLA(2)-IB in RPE phagocytosis...... and in RPE from KO mice. Exogenous addition of enzymatically active and inactive sPLA(2)-IB reduced phagocytosis in ARPE-19 and primary mouse RPE cells. Finally, sPLA(2)-IB did not seem to affect the iPLA(2)-VIA promoter. CONCLUSION: The present study confirms the involvement of iPLA(2)-VIA in efficient RPE...

  6. Endo180 and MT1-MMP are involved in the phagocytosis of collagen scaffolds by macrophages and is regulated by interferon-gamma.

    Science.gov (United States)

    Ye, Q; Xing, Q; Ren, Y; Harmsen, M C; Bank, R A

    2010-10-07

    Subcutaneously implanted disks of hexamethylenediisocyanate or glutaraldehyde cross-linked sheep collagen (referred to as HDSC and GDSC, respectively) in mice show large differences in degradation rate. Although comparable numbers of macrophages are seen in HDSC and GDSC, phagocytosis of collagen by macrophages occurred only in GDSC. The molecular mechanisms involved in the phagocytosis of collagen by macrophages are essentially unknown. Immunofluorescence and RT-PCR showed that Endo180 was expressed in GDSC only. TissueFaxs showed that Endo180 co-localized with MT1-MMP on F4÷80 positive cells, which is likely responsible for the phagocytosis in GDSC. RT-PCR further showed that Endo180 expression correlated with high levels of IFN-γ mRNA. In vitro, IFN-γ induced the expression Endo180 and MT1-MMP in murine macrophages cultured on collagen type I (although too high levels of IFN-γ dampened the expression of Endo180 and MT1-MMP). Moreover, the expression of Endo180 and MT1-MMP induced by IFN-γ can be inhibited through IL-10. The differences in microenvironment between GDSC and HDSC (high IFN-γ and low IL-10 levels in GDSC, low IFN-γ and high IL-10 levels in HDSC) provide an explanation why phagocytosis of collagen by macrophages is only seen in GDSC. In summary, we show for the first time that the IFN-γ dependent co-expression of Endo180 and MT1-MMP on macrophages coincides with collagen phagocytosis, thus providing evidence that the mechanism of collagen phagocytosis operating in the foreign body reaction by macrophages is comparable with the mechanism of intracellular collagen degradation by fibroblasts seen under physiological conditions.

  7. Endo180 and MT1-MMP are involved in the phagocytosis of collagen scaffolds by macrophages and is regulated by interferon-gamma

    Directory of Open Access Journals (Sweden)

    Q Ye

    2010-10-01

    Full Text Available Subcutaneously implanted disks of hexamethylenediisocyanate or glutaraldehyde cross-linked sheep collagen (referred to as HDSC and GDSC, respectively in mice show large differences in degradation rate. Although comparable numbers of macrophages are seen in HDSC and GDSC, phagocytosis of collagen by macrophages occurred only in GDSC. The molecular mechanisms involved in the phagocytosis of collagen by macrophages are essentially unknown. Immunofluorescence and RT-PCR showed that Endo180 was expressed in GDSC only. TissueFaxs showed that Endo180 co-localized with MT1-MMP on F4/80 positive cells, which is likely responsible for the phagocytosis in GDSC. RT-PCR further showed that Endo180 expression correlated with high levels of IFN-gamma mRNA. In vitro, IFN-gamma induced the expression Endo180 and MT1-MMP in murine macrophages cultured on collagen type I (although too high levels of IFN-gamma dampened the expression of Endo180 and MT1-MMP. Moreover, the expression of Endo180 and MT1-MMP induced by IFN-gamma can be inhibited through IL-10. The differences in microenvironment between GDSC and HDSC (high IFN-gamma and low IL-10 levels in GDSC, low IFN- gamma and high IL-10 levels in HDSC provide an explanation why phagocytosis of collagen by macrophages is only seen in GDSC. In summary, we show for the first time that the IFN-gamma dependent co-expression of Endo180 and MT1-MMP on macrophages coincides with collagen phagocytosis, thus providing evidence that the mechanism of collagen phagocytosis operating in the foreign body reaction by macrophages is comparable with the mechanism of intracellular collagen degradation by fibroblasts seen under physiological conditions.

  8. The nuclear factor kappa B (NF-κB) activation is required for phagocytosis of staphylococcus aureus by RAW 264.7 cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Fei, E-mail: zhufei@zju.edu.cn; Yue, Wanfu; Wang, Yongxia

    2014-10-01

    Nuclear factor kappa B (NF-κB) is a ubiquitous transcription factor which controls the expression of various genes involved in immune responses. However, it is not clear whether NF-κB activation is critical for phagocytosis when Staphylococcus aureus is the pathogen. Using oligonucleotide microarrays, we investigated whether NF-κB cascade genes are altered in a mouse leukemic monocyte macrophage cell line (RAW 264.7) when the cells were stimulated to activate a host innate immune response against live S. aureus or heat-inactivated S. aureus (HISA). NF-κB cascade genes such as Nfκb1, Nfκbiz, Nfκbie, Rel, Traf1 and Tnfaip3 were up-regulated by all treatments at one hour after incubation. NF-κB play an important role in activating phagocytosis in RAW 264.7 cells infected with S. aureus. Inhibition of NF-κB significantly blocked phagocytosis of fluorescently labeled S. aureus and decreased the expression of NFκB1, IL1α, IL1β and TLR2 in this cell line. Our results demonstrate that S. aureus may activate the NF-κB pathway and that NF-κB activation is required for phagocytosis of S. aureus by macrophages. - Highlights: • NF-κB cascade genes such as Nfκb1 and Traf1 were up-regulated by heat-inactivated S. aureus. • Inhibition of NF-κB significantly blocked phagocytosis of fluorescently labeled S. aureus. • NF-κB activation is required for phagocytosis of S. aureus by macrophages.

  9. Non-thermal plasma technology for the development of antimicrobial surfaces: a review

    Science.gov (United States)

    Nikiforov, Anton; Deng, Xiaolong; Xiong, Qing; Cvelbar, U.; DeGeyter, N.; Morent, R.; Leys, Christophe

    2016-05-01

    Antimicrobial coatings are in high demand in many fields including the biomaterials and healthcare sectors. Within recent progress in nanoscience and engineering at the nanoscale, preparation of nanocomposite films containing metal nanoparticles (such as silver nanoparticles, copper nanoparticles, zinc oxide nanoparticles) is becoming an important step in manufacturing biomaterials with high antimicrobial activity. Controlled release of antibiotic agents and eliminating free nanoparticles are of equal importance for engineering antimicrobial nanocomposite materials. Compared to traditional chemical ‘wet’ methods, plasma deposition and plasma polymerization are promising approaches for the fabrication of nanocomposite films with the advantages of gas phase dry processes, effective use of chemicals and applicability to various substrates. In this article, we present a short overview of state-of-the-art engineering of antimicrobial materials based on the use of non-thermal plasmas at low and atmospheric pressure.

  10. Bruton's Tyrosine Kinase (BTK and Vav1 contribute to Dectin1-dependent phagocytosis of Candida albicans in macrophages.

    Directory of Open Access Journals (Sweden)

    Karin Strijbis

    Full Text Available Phagocytosis of the opportunistic fungal pathogen Candida albicans by cells of the innate immune system is vital to prevent infection. Dectin-1 is the major phagocytic receptor involved in anti-fungal immunity. We identify two new interacting proteins of Dectin-1 in macrophages, Bruton's Tyrosine Kinase (BTK and Vav1. BTK and Vav1 are recruited to phagocytic cups containing C. albicans yeasts or hyphae but are absent from mature phagosomes. BTK and Vav1 localize to cuff regions surrounding the hyphae, while Dectin-1 lines the full length of the phagosome. BTK and Vav1 colocalize with the lipid PI(3,4,5P3 and F-actin at the phagocytic cup, but not with diacylglycerol (DAG which marks more mature phagosomal membranes. Using a selective BTK inhibitor, we show that BTK contributes to DAG synthesis at the phagocytic cup and the subsequent recruitment of PKCε. BTK- or Vav1-deficient peritoneal macrophages display a defect in both zymosan and C. albicans phagocytosis. Bone marrow-derived macrophages that lack BTK or Vav1 show reduced uptake of C. albicans, comparable to Dectin1-deficient cells. BTK- or Vav1-deficient mice are more susceptible to systemic C. albicans infection than wild type mice. This work identifies an important role for BTK and Vav1 in immune responses against C. albicans.

  11. Shrimp miR-12 Suppresses White Spot Syndrome Virus Infection by Synchronously Triggering Antiviral Phagocytosis and Apoptosis Pathways

    Science.gov (United States)

    Shu, Le; Zhang, Xiaobo

    2017-01-01

    Growing evidence has indicated that the innate immune system can be regulated by microRNAs (miRNAs). However, the mechanism underlying miRNA-mediated simultaneous activation of multiple immune pathways remains unknown. To address this issue, the role of host miR-12 in shrimp (Marsupenaeus japonicus) antiviral immune responses was characterized in the present study. The results indicated that miR-12 participated in virus infection, host phagocytosis, and apoptosis in defense against white spot syndrome virus invasion. miR-12 could simultaneously trigger phagocytosis, apoptosis, and antiviral immunity through the synchronous downregulation of the expression of shrimp genes [PTEN (phosphatase and tensin homolog) and BI-1(transmembrane BAX inhibitor motif containing 6)] and the viral gene (wsv024). Further analysis showed that miR-12 could synchronously mediate the 5′–3′ exonucleolytic degradation of its target mRNAs, and this degradation terminated in the vicinity of the 3′ untranslated region sequence complementary to the seed sequence of miR-12. Therefore, the present study showed novel aspects of the miRNA-mediated simultaneous regulation of multiple immune pathways. PMID:28824612

  12. Dopamine modulates hemocyte phagocytosis via a D1-like receptor in the rice stem borer, Chilo suppressalis.

    Science.gov (United States)

    Wu, Shun-Fan; Xu, Gang; Stanley, David; Huang, Jia; Ye, Gong-Yin

    2015-07-16

    Dopamine (DA) is a signal moiety bridging the nervous and immune systems. DA dysregulation is linked to serious human diseases, including addiction, schizophrenia, and Parkinson's disease. However, DA actions in the immune system remain incompletely understood. In this study, we found that DA modulates insect hemocyte phagocytosis using hemocytes prepared from the rice stem borer (RSB), Chilo suppressalis. We investigated whether insect hemocytes are capable of de novo DA production. Here we show that exposing hemocytes to lipopolysaccharide (LPS) led to induction of DA-generating enzymes. Exogenous DA induced rapid phosphorylation of extracellular signal-regulated kinase (ERK) in naïve hemocytes. Activation of ERK was inhibited by preincubating with a DOP1 receptor antagonist. Thus, DA signaling via the DOP1 receptor may contribute to early hemocyte activation. DA synthesized and released from hemocytes may act in an autocrine mechanism to stimulate or maintain phagocytic activity. Consistent with this hypothesis, we found that inhibition of DA synthesis with α-methyl-DL-tyrosine methyl ester hydrochloride or blockage of DOP1 receptor with antagonist SCH23390 impaired hemocyte phagocytosis. Topical DA application also significantly decreased RSB mortality following challenge with the insect pathogenic fungus, Beauveria bassiana. We infer that a DA-dependent signaling system operates in hemocytes to mediate phagocytotic functions.

  13. The cellular prion protein negatively regulates phagocytosis and cytokine expression in murine bone marrow-derived macrophages.

    Directory of Open Access Journals (Sweden)

    Min Wang

    Full Text Available The cellular prion protein (PrP(C is a glycosylphosphatidylinositol (GPI-anchored glycoprotein on the cell surface. Previous studies have demonstrated contradictory roles for PrP(C in connection with the phagocytic ability of macrophages. In the present work, we investigated the function of PrP(C in phagocytosis and cytokine expression in bone marrow-derived macrophages infected with Escherichia coli. E. coli infection induced an increase in the PRNP mRNA level. Knockout of PrP(C promoted bacterial uptake; upregulated Rab5, Rab7, and Eea1 mRNA expression; and increased the recruitment of lysosomal-associated membrane protein-2 to phagosomes, suggesting enhanced microbicidal activity. Remarkably, knockout of PrP(C suppressed the proliferation of internalized bacteria and increased the expression of cytokines such as interleukin-1β. Collectively, our data reveal an important role of PrP(C as a negative regulator for phagocytosis, phagosome maturation, cytokine expression, and macrophage microbicidal activity.

  14. Protein disulfide isomerase (PDI) associates with NADPH oxidase and is required for phagocytosis of Leishmania chagasi promastigotes by macrophages.

    Science.gov (United States)

    Santos, Célio X C; Stolf, Beatriz S; Takemoto, Paulo V A; Amanso, Angélica M; Lopes, Lucia R; Souza, Edna B; Goto, Hiro; Laurindo, Francisco R M

    2009-10-01

    PDI, a redox chaperone, is involved in host cell uptake of bacteria/viruses, phagosome formation, and vascular NADPH oxidase regulation. PDI involvement in phagocyte infection by parasites has been poorly explored. Here, we investigated the role of PDI in in vitro infection of J774 macrophages by amastigote and promastigote forms of the protozoan Leishmania chagasi and assessed whether PDI associates with the macrophage NADPH oxidase complex. Promastigote but not amastigote phagocytosis was inhibited significantly by macrophage incubation with thiol/PDI inhibitors DTNB, bacitracin, phenylarsine oxide, and neutralizing PDI antibody in a parasite redox-dependent way. Binding assays indicate that PDI preferentially mediates parasite internalization. Bref-A, an ER-Golgi-disrupting agent, prevented PDI concentration in an enriched macrophage membrane fraction and promoted a significant decrease in infection. Promastigote phagocytosis was increased further by macrophage overexpression of wild-type PDI and decreased upon transfection with an antisense PDI plasmid or PDI siRNA. At later stages of infection, PDI physically interacted with L. chagasi, as revealed by immunoprecipitation data. Promastigote uptake was inhibited consistently by macrophage preincubation with catalase. Additionally, loss- or gain-of-function experiments indicated that PMA-driven NADPH oxidase activation correlated directly with PDI expression levels. Close association between PDI and the p22phox NADPH oxidase subunit was shown by confocal colocalization and coimmunoprecipitation. These results provide evidence that PDI not only associates with phagocyte NADPH oxidase but also that PDI is crucial for efficient macrophage infection by L. chagasi.

  15. Bruton's Tyrosine Kinase (BTK) and Vav1 Contribute to Dectin1-Dependent Phagocytosis of Candida albicans in Macrophages

    Science.gov (United States)

    Strijbis, Karin; Tafesse, Fikadu G.; Fairn, Gregory D.; Witte, Martin D.; Dougan, Stephanie K.; Watson, Nicki; Spooner, Eric; Esteban, Alexandre; Vyas, Valmik K.; Fink, Gerald R.; Grinstein, Sergio; Ploegh, Hidde L.

    2013-01-01

    Phagocytosis of the opportunistic fungal pathogen Candida albicans by cells of the innate immune system is vital to prevent infection. Dectin-1 is the major phagocytic receptor involved in anti-fungal immunity. We identify two new interacting proteins of Dectin-1 in macrophages, Bruton's Tyrosine Kinase (BTK) and Vav1. BTK and Vav1 are recruited to phagocytic cups containing C. albicans yeasts or hyphae but are absent from mature phagosomes. BTK and Vav1 localize to cuff regions surrounding the hyphae, while Dectin-1 lines the full length of the phagosome. BTK and Vav1 colocalize with the lipid PI(3,4,5)P3 and F-actin at the phagocytic cup, but not with diacylglycerol (DAG) which marks more mature phagosomal membranes. Using a selective BTK inhibitor, we show that BTK contributes to DAG synthesis at the phagocytic cup and the subsequent recruitment of PKCε. BTK- or Vav1-deficient peritoneal macrophages display a defect in both zymosan and C. albicans phagocytosis. Bone marrow-derived macrophages that lack BTK or Vav1 show reduced uptake of C. albicans, comparable to Dectin1-deficient cells. BTK- or Vav1-deficient mice are more susceptible to systemic C. albicans infection than wild type mice. This work identifies an important role for BTK and Vav1 in immune responses against C. albicans. PMID:23825946

  16. Virulent and Vaccine Strains of Streptococcus equi ssp. zooepidemicus Have Different Influences on Phagocytosis and Cytokine Secretion of Macrophages.

    Science.gov (United States)

    Jie, Peng; Zhe, Ma; Chengwei, Hua; Huixing, Lin; Hui, Zhang; Chengping, Lu; Hongjie, Fan

    2017-01-06

    Swine streptococcosis is a significant threat to the Chinese pig industry, and Streptococcus equi ssp. zooepidemicus (SEZ) is one of the major pathogens. SEZ ATCC35246 is a classical virulent strain, while SEZ ST171 is a Chinese attenuated vaccine strain. In this study, we employed stable isotope labeling by amino acids in cell culture and liquid chromatography-mass spectrometry (LC-MS) to determine the differential response of macrophages to infection by these two strains. Eighty-seven upregulated proteins and 135 downregulated proteins were identified. The proteomic results were verified by real-time polymerase chain reaction for 10 chosen genes and Western blotting for three proteins. All differentially abundant proteins were analyzed for their Gene Ontology and Kyoto Encyclopedia of Genes and Genomes annotations. Certain downregulated proteins were associated with immunity functions, and the upregulated proteins were related to cytomembrane and cytoskeleton regulation. The phagocytosis rate and cytokine genes transcription in Raw264.7 cells during SEZ ATCC35246 and ST171 infection were detected to confirm the bioinformatics results. These results showed that different effects on macrophage phagocytosis and cytokine expression might explain the different phenotypes of SEZ ATCC35246 and ST171 infection. This research provided clues to the mechanisms of host immunity responses to SEZ ST171and SEZ ATCC35246, which could identify potential therapy and vaccine development targets.

  17. ROCK inhibition with fasudil promotes early functional recovery of spinal cord injury in rats by enhancing microglia phagocytosis.

    Science.gov (United States)

    Fu, Pei-cai; Tang, Rong-hua; Wan, Yue; Xie, Min-jie; Wang, Wei; Luo, Xiang; Yu, Zhi-yuan

    2016-02-01

    Emerging evidence indicates that microglia activation plays an important role in spinal cord injury (SCI) caused by trauma. Studies have found that inhibiting the Rho/Rho-associated protein kinase (ROCK) signaling pathway can reduce inflammatory cytokine production by microglia. In this study, Western blotting was conducted to detect ROCK2 expression after the SCI; the ROCK Activity Assay kit was used for assay of ROCK pathway activity; microglia morphology was examined using the CD11b antibody; electron microscopy was used to detect microglia phagocytosis; TUNEL was used to detect tissue cell apoptosis; myelin staining was performed using an antibody against myelin basic protein (MBP); behavioral outcomes were evaluated according to the methods of Basso, Beattie, and Bresnahan (BBB). We observed an increase in ROCK activity and microglial activation after SCI. The microglia became larger and rounder and contained myelin-like substances. Furthermore, treatment with fasudil inhibited neuronal cells apoptosis, alleviated demyelination and the formation of cavities, and improved motor recovery. The experimental evidence reveals that the ROCK inhibitor fasudil can regulate microglial activation, promote cell phagocytosis, and improve the SCI microenvironment to promote SCI repair. Thus, fasudil may be useful for the treatment of SCI.

  18. Novel histone-derived antimicrobial peptides use different antimicrobial mechanisms.

    Science.gov (United States)

    Pavia, Kathryn E; Spinella, Sara A; Elmore, Donald E

    2012-03-01

    The increase in multidrug resistant bacteria has sparked an interest in the development of novel antibiotics. Antimicrobial peptides that operate by crossing the cell membrane may also have the potential to deliver drugs to intracellular targets. Buforin 2 (BF2) is an antimicrobial peptide that shares sequence identity with a fragment of histone subunit H2A and whose bactericidal mechanism depends on membrane translocation and DNA binding. Previously, novel histone-derived antimicrobial peptides (HDAPs) were designed based on properties of BF2, and DesHDAP1 and DesHDAP3 showed significant antibacterial activity. In this study, their DNA binding, permeabilization, and translocation abilities were assessed independently and compared to antibacterial activity to determine whether they share a mechanism with BF2. To investigate the importance of proline in determining the peptides' mechanisms of action, proline to alanine mutants of the novel peptides were generated. DesHDAP1, which shows significant similarities to BF2 in terms of secondary structure, translocates effectively across lipid vesicle and bacterial membranes, while the DesHDAP1 proline mutant shows reduced translocation abilities and antimicrobial potency. In contrast, both DesHDAP3 and its proline mutant translocate poorly, though the DesHDAP3 proline mutant is more potent. Our findings suggest that a proline hinge can promote membrane translocation in some peptides, but that the extent of its effect on permeabilization depends on the peptide's amphipathic properties. Our results also highlight the different antimicrobial mechanisms exhibited by histone-derived peptides and suggest that histones may serve as a source of novel antimicrobial peptides with varied properties.

  19. Antimicrobial Resistance Mechanisms among Campylobacter

    Science.gov (United States)

    2013-01-01

    Campylobacter jejuni and Campylobacter coli are recognized as the most common causative agents of bacterial gastroenteritis in the world. Humans most often become infected by ingesting contaminated food, especially undercooked chicken, but also other sources of bacteria have been described. Campylobacteriosis is normally a self-limiting disease. Antimicrobial treatment is needed only in patients with more severe disease and in those who are immunologically compromised. The most common antimicrobial agents used in the treatment of Campylobacter infections are macrolides, such as erythromycin, and fluoroquinolones, such as ciprofloxacin. Tetracyclines have been suggested as an alternative choice in the treatment of clinical campylobacteriosis but in practice are not often used. However, during the past few decades an increasing number of resistant Campylobacter isolates have developed resistance to fluoroquinolones and other antimicrobials such as macrolides, aminoglycosides, and beta-lactams. Trends in antimicrobial resistance have shown a clear correlation between use of antibiotics in the veterinary medicine and animal production and resistant isolates of Campylobacter in humans. In this review, the patterns of emerging resistance to the antimicrobial agents useful in treatment of the disease are presented and the mechanisms of resistance to these drugs in Campylobacter are discussed. PMID:23865047

  20. Antimicrobial activities of squalamine mimics.

    Science.gov (United States)

    Kikuchi, K; Bernard, E M; Sadownik, A; Regen, S L; Armstrong, D

    1997-07-01

    We investigated the antimicrobial properties of compounds with structural features that were designed to mimic those of squalamine, an antibiotic isolated from the stomach of the dogfish shark. The mimics, like squalamine, are sterol-polyamine conjugates. Unlike squalamine, the mimics were simple to prepare, at high yield, from readily available starting materials. Several squalamine mimics showed activity against gram-negative rods, gram-positive cocci including methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecium, and fungi. Some had little or no hemolytic activity. The hydrophobicity of the sterol backbone and the length and the cationic charge of the side chains appeared to be critical determinants of activity. One of the squalamine mimics, SM-7, was bactericidal against Escherichia coli, Pseudomonas aeruginosa, and S. aureus; its activity was decreased by divalent or monovalent cations and by bovine serum albumin. Subinhibitory concentrations of SM-7 markedly enhanced the antimicrobial activity of rifampin against gram-negative rods. These results suggest that the compounds may disrupt an outer membrane of gram-negative rods. Squalamine mimics are a new class of broad-spectrum antimicrobial agents. The antagonism of their activity by serum and albumin and their hemolytic properties may limit their use as systemic agents. The squalamine mimics, because of their potencies, broad spectra of antimicrobial activity, and potential for systemic toxicity, appear to be good candidates for development as topical antimicrobial agents.

  1. Antimicrobial resistance mechanisms among Campylobacter.

    Science.gov (United States)

    Wieczorek, Kinga; Osek, Jacek

    2013-01-01

    Campylobacter jejuni and Campylobacter coli are recognized as the most common causative agents of bacterial gastroenteritis in the world. Humans most often become infected by ingesting contaminated food, especially undercooked chicken, but also other sources of bacteria have been described. Campylobacteriosis is normally a self-limiting disease. Antimicrobial treatment is needed only in patients with more severe disease and in those who are immunologically compromised. The most common antimicrobial agents used in the treatment of Campylobacter infections are macrolides, such as erythromycin, and fluoroquinolones, such as ciprofloxacin. Tetracyclines have been suggested as an alternative choice in the treatment of clinical campylobacteriosis but in practice are not often used. However, during the past few decades an increasing number of resistant Campylobacter isolates have developed resistance to fluoroquinolones and other antimicrobials such as macrolides, aminoglycosides, and beta-lactams. Trends in antimicrobial resistance have shown a clear correlation between use of antibiotics in the veterinary medicine and animal production and resistant isolates of Campylobacter in humans. In this review, the patterns of emerging resistance to the antimicrobial agents useful in treatment of the disease are presented and the mechanisms of resistance to these drugs in Campylobacter are discussed.

  2. Antimicrobial resistance patterns of phenotype Extended Spectrum ...

    African Journals Online (AJOL)

    In order to have adequate information for treatment of bacterial infections ... Antimicrobial susceptibility tests were carried out using various antimicrobial discs as per ... They consisted of 46 urine, 264 pus (from wound) and 20 blood samples.

  3. Antimicrobial stewardship in small animal veterinary practice

    DEFF Research Database (Denmark)

    Guardabassi, Luca; Prescott, John F

    2015-01-01

    Despite the increasing recognition of the critical role for antimicrobial stewardship in preventing the spread of multidrug-resistant bacteria, examples of effective antimicrobial stewardship programs are rare in small animal veterinary practice. This article highlights the basic requirements...

  4. molecular characterisation and antimicrobial resistance patterns of ...

    African Journals Online (AJOL)

    2013-03-03

    Mar 3, 2013 ... Conclusion: This study demonstrated that there is a significant level of antimicrobial ..... prevalence in their report. In this ... use of antimicrobial therapy of infections in man and ... by bacteriophage 933J from Escherichia coli.

  5. Synthetic biology of antimicrobial discovery

    Science.gov (United States)

    Zakeri, Bijan; Lu, Timothy K.

    2012-01-01

    Antibiotic discovery has a storied history. From the discovery of penicillin by Sir Alexander Fleming to the relentless quest for antibiotics by Selman Waksman, the stories have become like folklore, used to inspire future generations of scientists. However, recent discovery pipelines have run dry at a time when multidrug resistant pathogens are on the rise. Nature has proven to be a valuable reservoir of antimicrobial agents, which are primarily produced by modularized biochemical pathways. Such modularization is well suited to remodeling by an interdisciplinary approach that spans science and engineering. Herein, we discuss the biological engineering of small molecules, peptides, and non-traditional antimicrobials and provide an overview of the growing applicability of synthetic biology to antimicrobials discovery. PMID:23654251

  6. Antimicrobial Properties of Titanium Nanoparticles

    Science.gov (United States)

    Erdural, B. K.; Yurum, A.; Bakir, U.; Karakas, G.

    In the present study, nanostructured titania particles were synthesized using hydrothermal processing and their photocatalytic antimicrobial activities were characterized. Sol-gel synthesized TiO2 samples were treated with a two step hydrothermal treatment. The first stage treatment was the alkaline treatment with 10 M of NaOH for 48 h at 130°C, followed with the second step which applied with distilled water for 48 h at 200°C. Scanning Electron Microscope (SEM) images showed that alkaline treatment yields lamellar structure particles from the sol-gel synthesized anatase. Further treatment of nanoplates with distilled water results in crystal growth and the formation of nano structured thorn like particles. The photocatalytic antimicrobial activities of samples were determined against Escherichia coli under solar irradiation for 4 h. It was observed that the samples treated under alkaline conditions have higher antimicrobial activity than the untreated samples.

  7. Antimicrobial resistance in India: A review

    OpenAIRE

    2013-01-01

    Antimicrobial resistance is an important concern for the public health authorities at global level. However, in developing countries like India, recent hospital and some community based data showed increase in burden of antimicrobial resistance. Research related to antimicrobial use, determinants and development of antimicrobial resistance, regional variation and interventional strategies according to the existing health care situation in each country is a big challenge. This paper discusses ...

  8. A model system to study antimicrobial strategies in endodontic biofilms

    Directory of Open Access Journals (Sweden)

    Carlos Estrela

    2009-04-01

    Full Text Available The purpose of this work was to develop a model system to study antimicrobial strategies in endodontic biofilms. Enterococcus faecalis suspension was colonized in 10 human root canals. Five milliliters of Brain Heart Infusion (BHI were mixed with 5 mL of the bacterial inoculums (E. faecalis and inoculated with sufficient volume to fill the root canal during 60 days. This procedure was repeated every 72 h, always using 24-h pure culture prepared and adjusted to No. 1 MacFarland turbidity standard. Biofilm formation was analyzed by scanning electron microscopy (SEM. E. faecalis consistently adhered to collagen structure, colonized dentin surface, progressed towards the dentinal tubules and formed a biofilm. The proposed biofilm model seems to be viable for studies on antimicrobial strategies, and allows for a satisfactory colonization time of selected bacterial species with virulence and adherence properties.

  9. Spermicidal Activity of the Safe Natural Antimicrobial Peptide Subtilosin

    Directory of Open Access Journals (Sweden)

    Katia E. Sutyak

    2008-01-01

    Full Text Available Bacterial vaginosis (BV, a condition affecting millions of women each year, is primarily caused by the gram-variable organism Gardnerella vaginalis. A number of organisms associated with BV cases have been reported to develop multidrug resistance, leading to the need for alternative therapies. Previously, we reported the antimicrobial peptide subtilosin has proven antimicrobial activity against G. vaginalis, but not against the tested healthy vaginal microbiota of lactobacilli. After conducting tissue sensitivity assays using an ectocervical tissue model, we determined that human cells remained viable after prolonged exposures to partially-purified subtilosin, indicating the compound is safe for human use. Subtilosin was shown to eliminate the motility and forward progression of human spermatozoa in a dose-dependent manner, and can therefore be considered a general spermicidal agent. These results suggest subtilosin would be a valuable component in topical personal care products aimed at contraception and BV prophylaxis and treatment.

  10. Uses of antimicrobial genes from microbial genome

    Science.gov (United States)

    Sorek, Rotem; Rubin, Edward M.

    2013-08-20

    We describe a method for mining microbial genomes to discover antimicrobial genes and proteins having broad spectrum of activity. Also described are antimicrobial genes and their expression products from various microbial genomes that were found using this method. The products of such genes can be used as antimicrobial agents or as tools for molecular biology.

  11. Sixty years of antimicrobial use in animals

    DEFF Research Database (Denmark)

    Guardabassi, Luca

    2013-01-01

    This, the last in our series of feature articles celebrating 125 years of Veterinary Record, aims to provide an overview of antimicrobial use in animals. Starting with a journey through the history of antimicrobial use in animals, Luca Guardabassi gives his opinion on the current zoonotic risks...... associated with antimicrobial resistance and on how these risks might be tackled in the years to come....

  12. Antimicrobials Influence Bond Stiffness and Detachment of Oral Bacteria.

    Science.gov (United States)

    Song, L; Hou, J; van der Mei, H C; Veeregowda, D H; Busscher, H J; Sjollema, J

    2016-07-01

    adsorption to the bacterial cell surface and in line with changes in surface charge. Clinically, these findings suggest that accumulation of oral biofilm exposed to antimicrobials should be prevented (interdental cleaning aids, floss use), as removal becomes progressively more difficult upon multiple exposures.

  13. Differential expression of antimicrobial peptides in active and latent tuberculosis and its relationship with diabetes mellitus.

    Science.gov (United States)

    Gonzalez-Curiel, Irma; Castañeda-Delgado, Julio; Lopez-Lopez, Nallely; Araujo, Zaida; Hernandez-Pando, Rogelio; Gandara-Jasso, Benjamin; Macias-Segura, Noe; Enciso-Moreno, Antonio; Rivas-Santiago, Bruno

    2011-08-01

    Tuberculosis (TB) is one of the most important infectious diseases, causing 1.8 million deaths annually worldwide. This problem has increased because of the association with human immmunodeficiency virus and diabetes mellitus type 2, mainly in developing countries. In the past few years it has been highlighted the significance of antimicrobial peptides in the immunopathogenesis of TB ex vivo and in experimental models studies. In this study we analyzed the expression of CAMP, DEFA1, DEFB4, and DEFB103A in patients with latent TB and progressive TB with and without comorbidity with diabetes mellitus type 2. Antimicrobial peptide gene expression increased during progressive TB, which could be used as a biomarker for reactivation. By contrast, patients with diabetes mellitus type 2 have lower antimicrobial peptides gene expression, suggesting that the lack of its proper production in these patients contribute to enhance the risk for TB reactivation.

  14. Tick Thioester-Containing Proteins and Phagocytosis Do Not Affect Transmission of Borrelia afzelii from the Competent Vector Ixodes ricinus

    Science.gov (United States)

    Urbanová, Veronika; Hajdušek, Ondřej; Hönig Mondeková, Helena; Šíma, Radek; Kopáček, Petr

    2017-01-01

    The present concept of the transmission of Lyme disease from Borrelia-infected Ixodes sp. ticks to the naïve host assumes that a low number of spirochetes that manage to penetrate the midgut epithelium migrate through the hemocoel to the salivary glands and subsequently infect the host with the aid of immunomodulatory compounds present in tick saliva. Therefore, humoral and/or cellular immune reactions within the tick hemocoel may play an important role in tick competence to act as a vector for borreliosis. To test this hypothesis we have examined complement-like reactions in the hemolymph of the hard tick Ixodes ricinus against Borrelia afzelii (the most common vector and causative agent of Lyme disease in Europe). We demonstrate that I. ricinus hemolymph does not exhibit borreliacidal effects comparable to complement-mediated lysis of bovine sera. However, after injection of B. afzelii into the tick hemocoel, the spirochetes were efficiently phagocytosed by tick hemocytes and this cellular defense was completely eliminated by pre-injection of latex beads. As tick thioester-containing proteins (T-TEPs) are components of the tick complement system, we performed RNAi-mediated silencing of all nine genes encoding individual T-TEPs followed by in vitro phagocytosis assays. Silencing of two molecules related to the C3 complement component (IrC3-2 and IrC3-3) significantly suppressed phagocytosis of B. afzelii, while knockdown of IrTep (insect type TEP) led to its stimulation. However, RNAi-mediated silencing of T-TEPs or elimination of phagocytosis by injection of latex beads in B. afzelii-infected I. ricinus nymphs had no obvious impact on the transmission of spirochetes to naïve mice, as determined by B. afzelii infection of murine tissues following tick infestation. This result supports the concept that Borrelia spirochetes are capable of avoiding complement-related reactions within the hemocoel of ticks competent to transmit Lyme disease. PMID:28361038

  15. ANTIMICROBIAL REAGENTS AS FUNCTIONAL FINISHING FOR TEXTILES INTENDED FOR BIOMEDICAL APPLICATIONS. I. SYNTHETIC ORGANIC COMPOUNDS

    Directory of Open Access Journals (Sweden)

    Madalina Zanoaga

    2014-06-01

    Full Text Available This article offers an overview of some contemporary antimicrobial (biocides and biostatics agents used as functional finishing for textiles intended for biomedical applications. It reviews only synthetic agents, namely quaternary ammonium compounds, halogenated phenols, polybiguanides, N-halamines, and renewable peroxides, as a part of an extensive study currently in progress.

  16. Seven hours to adequate antimicrobial therapy in urosepsis using isothermal microcalorimetry.

    Science.gov (United States)

    Braissant, Olivier; Müller, Georg; Egli, Adrian; Widmer, Andreas; Frei, Reno; Halla, Armin; Wirz, Dieter; Gasser, Thomas C; Bachmann, Alexander; Wagenlehner, Florian; Bonkat, Gernot

    2014-02-01

    Urosepsis can progress toward severe sepsis, septic shock, and, ultimately, death. Rapid antimicrobial susceptibility testing is crucial to decrease mortality and morbidity. This report shows that isothermal microcalorimetry can provide an antibiogram within 7 h with a sensitivity of 95% and specificity of 91% using Vitek-2 system as a reference.

  17. ENDO180 AND MT1-MMP ARE INVOLVED IN THE PHAGOCYTOSIS OF COLLAGEN SCAFFOLDS BY MACROPHAGES AND IS REGULATED BY INTERFERON-GAMMA

    NARCIS (Netherlands)

    Ye, Qingsong; Xing, Quan; Ren, Yijin; Harmsen, Martin C.; Bank, Ruud A.

    2010-01-01

    Subcutaneously implanted disks of hexamethylenediisocyanate or glutaraldehyde cross-linked sheep collagen (referred to as HDSC and GDSC, respectively) in mice show large differences in degradation rate. Although comparable numbers of macrophages are seen in HDSC and GDSC, phagocytosis of collagen by

  18. Hydrogen peroxide is produced by E. coli challenged haemocytes and regulates phagocytosis, in the medfly Ceratitis capitata. The active role of superoxide dismutase.

    Science.gov (United States)

    Arbi, Marina; Pouliliou, Stamatia; Lampropoulou, Maria; Marmaras, Vassilis J; Tsakas, Sotiris

    2011-08-01

    Hydrogen peroxide (H(2)O(2)) participates as a second messenger in cell signaling. In this paper, the role of H(2)O(2) was investigated, in Escherichia coli phagocytosis by the haemocytes of the medfly Ceratitis capitata. Block of H(2)O(2) synthesis by specific enzymic inhibitors, namely N-ethylmaleimide (NEM) for NADPH oxidase and diethyldithiocarbamate (DDC) for SOD, resulted in the increase of E. coli phagocytosis. Immunoblot analysis, flow cytometry and confocal microscopy, revealed the constitutive expression of SOD, in the medfly haemocytes. Phagocytosis increased by small interfering RNA (siRNA) for SOD, revealing the active involvement of SOD and H(2)O(2). Immunoblot analysis showed an increase of the ERK1/2 phosphorylation, in the presence of the above H(2)O(2) synthesis enzymic inhibitors. In addition, confocal microscopy showed no co-localization of SOD with β integrin subunit. It appears that SOD participates in the regulation of bacterial phagocytosis, due to involvement of the produced H(2)O(2) in the differential phosphorylation of MAP kinases. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Combination of autoantibodies against different histone proteins influences complement-dependent phagocytosis of necrotic cell material by polymorphonuclear leukocytes in systemic lupus erythematosus

    DEFF Research Database (Denmark)

    Gullstrand, Birgitta; Lefort, Malin H; Tydén, Helena

    2012-01-01

    Polymorphonuclear leukocytes (PMN) with autoantibody-coated engulfed necrotic cell material (NC) are frequently seen in systemic lupus erythematosus (SLE). We evaluated the roles of complement, different antihistone antibodies (anti-H ab), and oxidative burst in the phagocytosis of NC by PMN...

  20. STUDY OF PRESCRIBING PATTERNS OF ANTIMICROBIAL AGENTS IN THE PAEDIATRIC WARDS AT TERTIARY TEACHING CARE HOSPITAL, GUJARAT

    Directory of Open Access Journals (Sweden)

    Vipul Prajapati* and J.D. Bhatt

    2012-07-01

    Full Text Available Background: Prescription of drugs, which needs to be continuously assessed and refined according to disease progression. It not only reflects the physician’s knowledge about drugs but also his/her skill in diagnose and attitude towards selecting the most appropriate cost-effective treatment. Antimicrobials are among the most commonly prescribed drugs in hospital. As per literature, they account for over 50% of total value of drugs sold in our country. Such studies have been sparse from Gujarat and hence, this study was undertaken.Methods: Retrospective study was carried out by collecting 350 prescriptions containing antimicrobial agents in paediatric department at Sir Sayajirao General (SSG Hospital, Vadodara to assess the prescribing patterns of antimicrobial agents. All information about the drugs details recorded in pre-tested Proforma that was finalized by our Pharmacology department. Results: Total 350 prescriptions containing 690 antimicrobial drugs were prescribed in patients during study. Of them aminoglycosides (233; 33.77% was frequently prescribed followed by β-lactam group (191; 27.68 and cephalosporins (176; 25.5%. Average numbers of antimicrobials per prescription was 1.97.Out of 690 antimicrobial prescribed, 576(83.48% were prescribed by generic name, while 114(16.52% were prescribed by trade name. Total numbers of antimicrobial prescribed by parenteral route were 599 (86.81%, while only 91(13.18% antimicrobial agents were prescribed by oral route. Out of 350 prescriptions two or more than two antimicrobial agents were prescribed in 249(71.14% prescriptions, while 101(28.85% prescriptions constitute one antimicrobial agent. Conclusion: Results indicates need for improving the prescribing pattern of drugs and minimizing the use of antimicrobial agents. It is suggested that further detail analysis to judge the rationality of the therapy is necessary.

  1. Antimicrobial Polymers with Metal Nanoparticles

    Directory of Open Access Journals (Sweden)

    Humberto Palza

    2015-01-01

    Full Text Available Metals, such as copper and silver, can be extremely toxic to bacteria at exceptionally low concentrations. Because of this biocidal activity, metals have been widely used as antimicrobial agents in a multitude of applications related with agriculture, healthcare, and the industry in general. Unlike other antimicrobial agents, metals are stable under conditions currently found in the industry allowing their use as additives. Today these metal based additives are found as: particles, ions absorbed/exchanged in different carriers, salts, hybrid structures, etc. One recent route to further extend the antimicrobial applications of these metals is by their incorporation as nanoparticles into polymer matrices. These polymer/metal nanocomposites can be prepared by several routes such as in situ synthesis of the nanoparticle within a hydrogel or direct addition of the metal nanofiller into a thermoplastic matrix. The objective of the present review is to show examples of polymer/metal composites designed to have antimicrobial activities, with a special focus on copper and silver metal nanoparticles and their mechanisms.

  2. Antimicrobial susceptibility of Lactobacillus rhamnosus

    NARCIS (Netherlands)

    Korhonen, J.M.; Hoek, van A.H.A.M.; Saarela, M.; Huys, G.; Tosi, L.; Mayrhofer, S.; Wright, A.

    2010-01-01

    We aimed to determine the minimum inhibitory concentrations (MICs) of Lactobacillus rhamnosus (n=75) strains, to study their antibiotic resistance genes with microarray, and to assess the microbiological cut-off values of tested antimicrobial agents. L. rhamnosus strains were tested with agar

  3. Helical Antimicrobial Sulfono- {gamma} -AApeptides

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yaqiong; Wu, Haifan; Teng, Peng; Bai, Ge; Lin, Xiaoyang; Zuo, Xiaobing; Cao, Chuanhai; Cai, Jianfeng

    2015-06-11

    Host-defense peptides (HDPs) such as magainin 2 have emerged as potential therapeutic agents combating antibiotic resistance. Inspired by their structures and mechanism of action, herein we report the fi rst example of antimicrobial helical sulfono- γ - AApeptide foldamers. The lead molecule displays broad-spectrum and potent antimicrobial activity against multi-drug-resistant Gram- positive and Gram-negative bacterial pathogens. Time-kill studies and fl uorescence microscopy suggest that sulfono- γ -AApeptides eradicate bacteria by taking a mode of action analogous to that of HDPs. Clear structure - function relationships exist in the studied sequences. Longer sequences, presumably adopting more-de fi ned helical structures, are more potent than shorter ones. Interestingly, the sequence with less helical propensity in solution could be more selective than the stronger helix-forming sequences. Moreover, this class of antimicrobial agents are resistant to proteolytic degradation. These results may lead to the development of a new class of antimicrobial foldamers combating emerging antibiotic-resistant pathogens.

  4. Antimicrobial activity of Securidaca longipedunculata.

    Science.gov (United States)

    Ajali, U; Chukwurah, B K C

    2004-11-01

    The folk herbal uses of Securidaca longipedunculata in the treatment of diarrhea, boils, gonorrhea, and cough prompted phytochemical analyses and antimicrobial activity screening of extracts of the root. Some flavonoids isolated showed activity against many micro-organisms. These flavonoids were isolated using chromatographic methods.

  5. Antimicrobial Activity of Resveratrol Analogues

    Directory of Open Access Journals (Sweden)

    Malik Chalal

    2014-06-01

    Full Text Available Stilbenes, especially resveratrol and its derivatives, have become famous for their positive effects on a wide range of medical disorders, as indicated by a huge number of published studies. A less investigated area of research is their antimicrobial properties. A series of 13 trans-resveratrol analogues was synthesized via Wittig or Heck reactions, and their antimicrobial activity assessed on two different grapevine pathogens responsible for severe diseases in the vineyard. The entire series, together with resveratrol, was first evaluated on the zoospore mobility and sporulation level of Plasmopara viticola (the oomycete responsible for downy mildew. Stilbenes displayed a spectrum of activity ranging from low to high. Six of them, including the most active ones, were subsequently tested on the development of Botrytis cinerea (fungus responsible for grey mold. The results obtained allowed us to identify the most active stilbenes against both grapevine pathogens, to compare the antimicrobial activity of the evaluated series of stilbenes, and to discuss the relationship between their chemical structure (number and position of methoxy and hydroxy groups and antimicrobial activity.

  6. Progress Report

    DEFF Research Database (Denmark)

    Duer, Karsten

    1999-01-01

    Progress report describing the work carried out by the Danish participant in the ALTSET project in the period January 1999 to July 1999.......Progress report describing the work carried out by the Danish participant in the ALTSET project in the period January 1999 to July 1999....

  7. Combating Antimicrobial Resistance in Foodborne Microorganisms.

    Science.gov (United States)

    Lai, Edward P C; Iqbal, Zafar; Avis, Tyler J

    2016-02-01

    This review addresses an important public health hazard affecting food safety. Antimicrobial agents are used in foods to reduce or eliminate microorganisms that cause disease. Many traditional organic compounds, novel synthetic organic agents, natural products, peptides, and proteins have been extensively studied for their effectiveness as antimicrobial agents against foodborne Campylobacter spp., Escherichia coli, Listeria spp. and Salmonella. However, antimicrobial resistance can develop in microorganisms, enhancing their ability to withstand the inhibiting or killing action of antimicrobial agents. Knowledge gaps still exist with regard to the actual chemical and microbiological mechanisms that must be identified to facilitate the search for new antimicrobial agents. Technical implementation of antimicrobial active packing films and coatings against target microorganisms must also be improved for extended product shelf life. Recent advances in antimicrobial susceptibility testing can provide researchers with new momentum to pursue their quest for a resistance panacea.

  8. Molecular Pathways: Activating T Cells after Cancer Cell Phagocytosis from Blockade of CD47 "Don't Eat Me" Signals.

    Science.gov (United States)

    McCracken, Melissa N; Cha, Adriel C; Weissman, Irving L

    2015-08-15

    Recent advances with immunotherapy agents for the treatment of cancer have provided remarkable, and in some cases, curative results. Our laboratory has identified CD47 as an important "don't eat me" signal expressed on malignant cells. Blockade of the CD47:SIRP-α axis between tumor cells and innate immune cells (monocytes, macrophages, and dendritic cells) increases tumor cell phagocytosis in both solid tumors (including, but not limited to, bladder, breast, colon, lung, and pancreatic) and hematologic malignancies. These phagocytic innate cells are also professional antigen-presenting cells (APC), providing a link from innate to adaptive antitumor immunity. Preliminary studies have demonstrated that APCs present antigens from phagocytosed tumor cells, causing T-cell activation. Therefore, agents that block the CD47:SIRP-α engagement are attractive therapeutic targets as a monotherapy or in combination with additional immune-modulating agents for activating antitumor T cells in vivo.

  9. Anti-CD47 Treatment Stimulates Phagocytosis of Glioblastoma by M1 and M2 Polarized Macrophages and Promotes M1 Polarized Macrophages In Vivo.

    Directory of Open Access Journals (Sweden)

    Michael Zhang

    Full Text Available Tumor-associated macrophages (TAMs represent an important cellular subset within the glioblastoma (WHO grade IV microenvironment and are a potential therapeutic target. TAMs display a continuum of different polarization states between antitumorigenic M1 and protumorigenic M2 phenotypes, with a lower M1/M2 ratio correlating with worse prognosis. Here, we investigated the effect of macrophage polarization on anti-CD47 antibody-mediated phagocytosis of human glioblastoma cells in vitro, as well as the effect of anti-CD47 on the distribution of M1 versus M2 macrophages within human glioblastoma cells grown in mouse xenografts. Bone marrow-derived mouse macrophages and peripheral blood-derived human macrophages were polarized in vitro toward M1 or M2 phenotypes and verified by flow cytometry. Primary human glioblastoma cell lines were offered as targets to mouse and human M1 or M2 polarized macrophages in vitro. The addition of an anti-CD47 monoclonal antibody led to enhanced tumor-cell phagocytosis by mouse and human M1 and M2 macrophages. In both cases, the anti-CD47-induced phagocytosis by M1 was more prominent than that for M2. Dissected tumors from human glioblastoma xenografted within NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice and treated with anti-CD47 showed a significant increase of M1 macrophages within the tumor. These data show that anti-CD47 treatment leads to enhanced tumor cell phagocytosis by both M1 and M2 macrophage subtypes with a higher phagocytosis rate by M1 macrophages. Furthermore, these data demonstrate that anti-CD47 treatment alone can shift the phenotype of macrophages toward the M1 subtype in vivo.

  10. Anti-CD47 Treatment Stimulates Phagocytosis of Glioblastoma by M1 and M2 Polarized Macrophages and Promotes M1 Polarized Macrophages In Vivo

    Science.gov (United States)

    Kahn, Suzana A.; Azad, Tej D.; Gholamin, Sharareh; Xu, Chelsea Y.; Liu, Jie; Achrol, Achal S.; Richard, Chase; Sommerkamp, Pia; Schoen, Matthew Kenneth; McCracken, Melissa N.; Majeti, Ravi; Weissman, Irving; Mitra, Siddhartha S.; Cheshier, Samuel H.

    2016-01-01

    Tumor-associated macrophages (TAMs) represent an important cellular subset within the glioblastoma (WHO grade IV) microenvironment and are a potential therapeutic target. TAMs display a continuum of different polarization states between antitumorigenic M1 and protumorigenic M2 phenotypes, with a lower M1/M2 ratio correlating with worse prognosis. Here, we investigated the effect of macrophage polarization on anti-CD47 antibody-mediated phagocytosis of human glioblastoma cells in vitro, as well as the effect of anti-CD47 on the distribution of M1 versus M2 macrophages within human glioblastoma cells grown in mouse xenografts. Bone marrow-derived mouse macrophages and peripheral blood-derived human macrophages were polarized in vitro toward M1 or M2 phenotypes and verified by flow cytometry. Primary human glioblastoma cell lines were offered as targets to mouse and human M1 or M2 polarized macrophages in vitro. The addition of an anti-CD47 monoclonal antibody led to enhanced tumor-cell phagocytosis by mouse and human M1 and M2 macrophages. In both cases, the anti-CD47-induced phagocytosis by M1 was more prominent than that for M2. Dissected tumors from human glioblastoma xenografted within NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice and treated with anti-CD47 showed a significant increase of M1 macrophages within the tumor. These data show that anti-CD47 treatment leads to enhanced tumor cell phagocytosis by both M1 and M2 macrophage subtypes with a higher phagocytosis rate by M1 macrophages. Furthermore, these data demonstrate that anti-CD47 treatment alone can shift the phenotype of macrophages toward the M1 subtype in vivo. PMID:27092773

  11. The adaptor molecule Nck localizes the WAVE complex to promote actin polymerization during CEACAM3-mediated phagocytosis of bacteria.

    Directory of Open Access Journals (Sweden)

    Stefan Pils

    Full Text Available BACKGROUND: CEACAM3 is a granulocyte receptor mediating the opsonin-independent recognition and phagocytosis of human-restricted CEACAM-binding bacteria. CEACAM3 function depends on an intracellular immunoreceptor tyrosine-based activation motif (ITAM-like sequence that is tyrosine phosphorylated by Src family kinases upon receptor engagement. The phosphorylated ITAM-like sequence triggers GTP-loading of Rac by directly associating with the guanine nucleotide exchange factor (GEF Vav. Rac stimulation in turn is critical for actin cytoskeleton rearrangements that generate lamellipodial protrusions and lead to bacterial uptake. PRINCIPAL FINDINGS: In our present study we provide biochemical and microscopic evidence that the adaptor proteins Nck1 and Nck2, but not CrkL, Grb2 or SLP-76, bind to tyrosine phosphorylated CEACAM3. The association is phosphorylation-dependent and requires the Nck SH2 domain. Overexpression of the isolated Nck1 SH2 domain, RNAi-mediated knock-down of Nck1, or genetic deletion of Nck1 and Nck2 interfere with CEACAM3-mediated bacterial internalization and with the formation of lamellipodial protrusions. Nck is constitutively associated with WAVE2 and directs the actin nucleation promoting WAVE complex to tyrosine phosphorylated CEACAM3. In turn, dominant-negative WAVE2 as well as shRNA-mediated knock-down of WAVE2 or the WAVE-complex component Nap1 reduce internalization of bacteria. CONCLUSIONS: Our results provide novel mechanistic insight into CEACAM3-initiated phagocytosis. We suggest that the CEACAM3 ITAM-like sequence is optimized to co-ordinate a minimal set of cellular factors needed to efficiently trigger actin-based lamellipodial protrusions and rapid pathogen engulfment.

  12. Abnormalities of Endocytosis, Phagocytosis, and Development Process in Dictyostelium Cells That Over-Express Acanthamoeba castellanii Metacaspase Protein.

    Directory of Open Access Journals (Sweden)

    Entsar Saheb

    2015-06-01

    Full Text Available Acanthamoeba castellanii forms a resistant cyst that protects the parasite against the host's immune response. Acanthamoeba Type-I metacaspase (Acmcp is a caspase-like protein that has been found to be expressed during the encystations. Dictyostelium discoideum is an organism closely related to Acanthamoeba useful for studying the molecular function of this protozoan caspase-like protein.The full length of Acmcp and a mutated version of the same gene, which lacks the proline rich N-terminal region (Acmcp-dpr, were cloned into the pDneo2a-GFP vector separately. The pDneo2a-GFP-Acmcp and pDneo2a-GFPAcmcp-dpr were electro-transfected into wild type D. discoideum cells to create cell lines that over-expressed Acmcp or Acmcp-dpr.Both cell lines that over-expressed Acmcp and Acmcp-dpr showed a significant increase in the fluid phase internalization and phagocytosis rate compared to the control cells. Additionally, the cells expressing the Acmcp-dpr mutant were unable to initiate early development and failed to aggregate or form fruiting bodies under starvation conditions, whereas Acmcp over-expressing cells showed the opposite phenomena. Quantitative cell death analysis provided additional support for these findings.Acmcp is involved in the processes of endocytosis and phagocytosis. In addition, the proline rich region in Acmcp is important for cellular development in Dictyostelium. Given its important role in the development process, metacaspase protein is proposed as a candidate drug target against infections caused by A. castellanii.

  13. Non-opsonic phagocytosis of homologous non-toxigenic and toxigenic Corynebacterium diphtheriae strains by human U-937 macrophages.

    Science.gov (United States)

    dos Santos, Cíntia Silva; dos Santos, Louisy Sanches; de Souza, Monica Cristina; dos Santos Dourado, Fernanda; de Souza de Oliveira Dias, Alexandre Alves; Sabbadini, Priscila Soares; Pereira, Gabriela Andrade; Cabral, Maulori Curié; Hirata Junior, Raphael; de Mattos-Guaraldi, Ana Luíza

    2010-01-01

    As interactions between bacteria and macrophages dictate the outcome of most infectious diseases, analyses of molecular mechanisms of non-opsonic phagocytosis should lead to new approaches for the prevention of diphtheria and systemic Corynebacterium diphtheriae infections. The present study aimed to evaluate human macrophage-bacteria interactions in the absence of opsonin antibodies and the influence of the tox gene on this process. Homologous C. diphtheriae tox+ and tox- strains were evaluated for adhesion, entering and survival within U-937 human macrophages at different incubation periods. Higher numbers of viable bacteria associated with and internalized by macrophages were demonstrated for the tox+ strain. However, viable intracellular bacteria were detected at T-24 hr only for the tox- strain. Cytoskeletal inhibitors, cytochalasin E, genistein and colchicine, inhibited intracellular viability of both strains at different levels. Bacterial replication was evidenced at T-24 hr in supernatants of monolayers infected with the tox- strain. Host cell death and nuclear alterations were evidenced by the Trypan blue exclusion assay and DAPI fluorescence microscopy. ELISA of histone-associated DNA fragments allowed detection of apoptosis and necrosis induced by tox+ and tox- strains at T-1 hr and T-3 hr. In conclusion, human macrophages in the absence of opsonins may not be promptly effective at killing diphtheria bacilli. The presence of the tox gene influences the susceptibility of C. diphtheriae to human macrophages and the outcome of non-opsonic phagocytosis. C. diphtheriae strains exhibit strategies to survive within macrophages and to exert apoptosis and necrosis in human phagocytic cells, independent of the tox gene.

  14. Large-scale purification of porcine or bovine photoreceptor outer segments for phagocytosis assays on retinal pigment epithelial cells.

    Science.gov (United States)

    Parinot, Célia; Rieu, Quentin; Chatagnon, Jonathan; Finnemann, Silvia C; Nandrot, Emeline F

    2014-12-12

    Analysis of one of the vital functions of retinal pigment epithelial (RPE) cells, the phagocytosis of spent aged distal fragments of photoreceptor outer segments (POS) can be performed in vitro. Photoreceptor outer segments with stacks of membranous discs containing the phototransduction machinery are continuously renewed in the retina. Spent POS are eliminated daily by RPE cells. Rodent, porcine/bovine and human RPE cells recognize POS from various species in a similar manner. To facilitate performing large series of experiments with little variability, a large stock of POS can be isolated from porcine eyes and stored frozen in aliquots. This protocol takes advantage of the characteristic of photopigments that display an orange color when kept in the dark. Under dim red light, retinae are collected in a buffer from opened eyecups cut in halves. The retinal cell suspension is homogenized, filtered and loaded onto a continuous sucrose gradient. After centrifugation, POS are located in a discrete band in the upper part of the gradient that has a characteristic orange color. POS are then collected, spun, resuspended sequentially in wash buffers, counted and aliquoted. POS obtained this way can be used for phagocytosis assays and analysis of protein activation, localization or interaction at various times after POS challenge. Alternatively, POS can be labeled with fluorophores, e.g., FITC, before aliquoting for subsequent fluorescence quantification of POS binding or engulfment. Other possible applications include the use of modified POS or POS challenge combined with stress conditions to study the effect of oxidative stress or aging on RPE cells.

  15. The stringent response of Staphylococcus aureus and its impact on survival after phagocytosis through the induction of intracellular PSMs expression.

    Directory of Open Access Journals (Sweden)

    Tobias Geiger

    Full Text Available The stringent response is initiated by rapid (pppGpp synthesis, which leads to a profound reprogramming of gene expression in most bacteria. The stringent phenotype seems to be species specific and may be mediated by fundamentally different molecular mechanisms. In Staphylococcus aureus, (pppGpp synthesis upon amino acid deprivation is achieved through the synthase domain of the bifunctional enzyme RSH (RelA/SpoT homolog. In several firmicutes, a direct link between stringent response and the CodY regulon was proposed. Wild-type strain HG001, rsh(Syn, codY and rsh(Syn, codY double mutants were analyzed by transcriptome analysis to delineate different consequences of RSH-dependent (pppGpp synthesis after induction of the stringent response by amino-acid deprivation. Under these conditions genes coding for major components of the protein synthesis machinery and nucleotide metabolism were down-regulated only in rsh positive strains. Genes which became activated upon (pppGpp induction are mostly regulated indirectly via de-repression of the GTP-responsive repressor CodY. Only seven genes, including those coding for the cytotoxic phenol-soluble modulins (PSMs, were found to be up-regulated via RSH independently of CodY. qtRT-PCR analyses of hallmark genes of the stringent response indicate that an RSH activating stringent condition is induced after uptake of S. aureus in human polymorphonuclear neutrophils (PMNs. The RSH activity in turn is crucial for intracellular expression of psms. Accordingly, rsh(Syn and rsh(Syn, codY mutants were less able to survive after phagocytosis similar to psm mutants. Intraphagosomal induction of psmα1-4 and/or psmβ1,2 could complement the survival of the rsh(Syn mutant. Thus, an active RSH synthase is required for intracellular psm expression which contributes to survival after phagocytosis.

  16. In vitro susceptibility of Campylobacter jejuni from Kuwait to tigecycline & other antimicrobial agents

    Directory of Open Access Journals (Sweden)

    M John Albert

    2013-01-01

    Full Text Available Background & objectives: There is an increasing frequency of resistance of Campylobacter jejuni to antimicrobial agents making treatment difficult. In this study, the in vitro susceptibility of C. jejuni isolates collected over an eight year period was tested against tigecycline, a glycylcycline, the previously tested antimicrobial agents in Kuwait, ciprofloxacin, erythromycin and tetracycline, and other antimicrobial agents not previously tested in Kuwait, amoxicillin-clavulanic acid, gentamicin, imipenem and meropenem. Methods: A total of 97 C. jejuni isolates from diarrhoeal stools of Kuwaiti patients during 2002-2010 were studied for susceptibility to the above antimicrobial agents by E test. Results: Erythromycin resistance increased from 5.0 per cent in 2002-2003 to 13.8 per cent in 2007-2010. The figures for ciprofloxacin resistance for the same periods were 53 and 65.5 per cent, respectively. Tetracycline resistance increased from 40.0 per cent in 2003-2006 to 62.1 per cent in 2007-2010 (P=0.05. However, all isolates were uniformly susceptible to tigecycline and other antimicrobial agents. Interpretation & conclusions: There was a progressive increase in the prevalence of resistance to ciprofloxacin, erythromycin and tetracycline. As all isolates were uniformly susceptible to tigecycline, this antimicrobial agent can be considered as a potential candidate for treatment in clinical studies.

  17. Direct Visualization of Spatial and Temporal Patterns of Antimicrobial Action within Model Oral Biofilms▿

    Science.gov (United States)

    Takenaka, Shoji; Trivedi, Harsh M.; Corbin, Audrey; Pitts, Betsey; Stewart, Philip S.

    2008-01-01

    A microscopic method for noninvasively visualizing the action of an antimicrobial agent inside a biofilm was developed and applied to describe spatial and temporal patterns of mouthrinse activity on model oral biofilms. Three species biofilms of Streptococcus oralis, Streptococcus gordonii, and Actinomyces naeslundii were grown in glass capillary flow cells. Bacterial cells were stained with the fluorogenic esterase substrate Calcien AM (CAM). Loss of green fluorescence upon exposure to an antimicrobial formulation was subsequently imaged by time-lapse confocal laser scanning microscopy. When an antimicrobial mouthrinse containing chlorhexidine digluconate was administered, a gradual loss of green fluorescence was observed that began at the periphery of cell clusters where they adjoined the flowing bulk fluid and progressed inward over a time period of several minutes. Image analysis was performed to quantify a penetration velocity of 4 μm/min. An enzyme-based antimicrobial formulation led to a gradual, continually slowing loss of fluorescence in a pattern that was qualitatively different from the behavior observed with chlorhexidine. Ethanol at 11.6% had little effect on the biofilm. None of these treatments resulted in the removal of biomass from the biofilm. Most methods to measure or visualize antimicrobial action in biofilms are destructive. Spatial information is important because biofilms are known for their structural and physiological heterogeneity. The CAM staining technique has the potential to provide information about the rate of antimicrobial penetration, the presence of tolerant subpopulations, and the extent of biomass removal effected by a treatment. PMID:18223108

  18. Progressive Business

    DEFF Research Database (Denmark)

    Christiansen, Christian O.

    2016-01-01

    Guest Post to the Society for U.S. Intellectual History Blog. Brief introduction to the book Progressive Business: An Intellectual History of the Role of Business in American Society, Oxford U.P., 2015.......Guest Post to the Society for U.S. Intellectual History Blog. Brief introduction to the book Progressive Business: An Intellectual History of the Role of Business in American Society, Oxford U.P., 2015....

  19. Antimicrobial Peptides from Marine Proteobacteria

    Directory of Open Access Journals (Sweden)

    Yannick Fleury

    2013-09-01

    Full Text Available After years of inadequate use and the emergence of multidrug resistant (MDR strains, the efficiency of “classical” antibiotics has decreased significantly. New drugs to fight MDR strains are urgently needed. Bacteria hold much promise as a source of unusual bioactive metabolites. However, the potential of marine bacteria, except for Actinomycetes and Cyanobacteria, has been largely underexplored. In the past two decades, the structures of several antimicrobial compounds have been elucidated in marine Proteobacteria. Of these compounds, polyketides (PKs, synthesised by condensation of malonyl-coenzyme A and/or acetyl-coenzyme A, and non-ribosomal peptides (NRPs, obtained through the linkage of (unusual amino acids, have recently generated particular interest. NRPs are good examples of naturally modified peptides. Here, we review and compile the data on the antimicrobial peptides isolated from marine Proteobacteria, especially NRPs.

  20. APD: the Antimicrobial Peptide Database.

    Science.gov (United States)

    Wang, Zhe; Wang, Guangshun

    2004-01-01

    An antimicrobial peptide database (APD) has been established based on an extensive literature search. It contains detailed information for 525 peptides (498 antibacterial, 155 antifungal, 28 antiviral and 18 antitumor). APD provides interactive interfaces for peptide query, prediction and design. It also provides statistical data for a select group of or all the peptides in the database. Peptide information can be searched using keywords such as peptide name, ID, length, net charge, hydrophobic percentage, key residue, unique sequence motif, structure and activity. APD is a useful tool for studying the structure-function relationship of antimicrobial peptides. The database can be accessed via a web-based browser at the URL: http://aps.unmc.edu/AP/main.html.

  1. Antimicrobial resistance in Rhodococcus equi.

    Science.gov (United States)

    Cisek, Agata A; Rzewuska, Magdalena; Witkowski, Lucjan; Binek, Marian

    2014-01-01

    Rhodococcus equi is an important etiologic agent of respiratory- and non-respiratory tract infections, diseases of animals and humans. Therapy includes the use of various group of chemotherapeutic agents, however resistance acquirement is quite common. To date there is no preferred treatment protocol for infections caused by isolates resistant to macrolides and rifampicin. The resistance acquirement is a result of many molecular mechanisms, some of which include alterations in the cell envelope composition and structure, activity of the efflux pumps, enzymatic destruction or inactivation of antibiotics, and changes in the target site. This paper contains an overview of antimicrobial susceptibility of R. equi, and explains the possible molecular mechanisms responsible for antimicrobial resistance in this particular microorganism.

  2. Cholic acid derivatives: novel antimicrobials.

    Science.gov (United States)

    Savage, P B; Li, C

    2000-02-01

    Mimics of squalamine and polymyxin B (PMB) have been prepared from cholic acid in hope of finding new antimicrobial agents. The squalamine mimics include the polyamine and sulphate functionalities found in the parent antibiotic, however, the positions relative to the steroid nucleus have been exchanged. The PMB mimics include the conservation of functionality among the polymyxin family of antibiotics, the primary amine groups and a hydrophobic chain. Although the squalamine and PMB mimics are morphologically dissimilar, they display similar activities. Both are simple to prepare and demonstrate broad spectrum antimicrobial activity against Gram-negative and Gram-positive organisms. Specific examples may be inactive alone, yet effectively permeabilise the outer membranes of Gram-negative bacteria rendering them sensitive to hydrophobic antibiotics. Problems associated with some of the squalamine and PMB mimics stem from their haemolytic activity and interactions with serum proteins, however, examples exist without these side effects which can sensitise Gram-negative bacteria to hydrophobic antibiotics.

  3. Antimicrobial Activity of Commercial Nanoparticles

    Science.gov (United States)

    Gajjar, Priyanka; Pettee, Brian; Britt, David W.; Huang, Wenjie; Johnson, William P.; Anderson, Anne J.

    2009-07-01

    Engineered nanoparticles are finding increased use in applications ranging from biosensors to prophylactic antimicrobials embedded in socks. The release of heavy metal-containing nanoparticles (NP) into the environment may be harmful to the efficacy of beneficial microbes that function in element cycling, pollutant degradation, and plant growth. Antimicrobial activity of commercial NP of Ag, CuO, and ZnO is demonstrated here against the beneficial soil microbe, Pseudomonas putida KT2440, which was modified to serve as a bioluminescent sentinel organism. "As manufactured" preparations of nano- Ag, -CuO, and -ZnO caused rapid, dose dependent loss of light output in the biosensor. Bulk equivalents of these products showed no inhibitory activity, indicating that particle size was determinant in activity.

  4. Antimicrobial resistance of mastitis pathogens.

    Science.gov (United States)

    Oliver, Stephen P; Murinda, Shelton E

    2012-07-01

    Antibiotics are used extensively in the dairy industry to combat disease and to improve animal performance. Antibiotics such as penicillin, cephalosporin, streptomycin, and tetracycline are used for the treatment and prevention of diseases affecting dairy cows caused by a variety of gram-positive and gram-negative bacteria. Antibiotics are often administrated routinely to entire herds to prevent mastitis during the dry period. An increase in the incidence of disease in a herd generally results in increased use of antimicrobials, which in turn increases the potential for antibiotic residues in milk and the potential for increased bacterial resistance to antimicrobials. Continued use of antibiotics in the treatment and prevention of diseases of dairy cows will continue to be scrutinized. It is clear that strategies employing the prudent use of antimicrobials are needed. This clearly illustrates the importance of effective herd disease prevention and control programs. Based on studies published to date, scientific evidence does not support widespread, emerging resistance among mastitis pathogens to antibacterial drugs even though many of these antibiotics have been used in the dairy industry for treatment and prevention of disease for several decades. However, it is clear that use of antibiotics in dairy cows can contribute to increased antimicrobial resistance. While antimicrobial resistance does occur, we are of the opinion that the advantages of using antibiotics for the treatment of mastitis far outweigh the disadvantages. The clinical consequences of antimicrobial resistance of dairy pathogens affecting humans appear small. Antimicrobial resistance among dairy pathogens, particularly those found in milk, is likely not a human health concern as long as the milk is pasteurized. However, there are an increasing number of people who choose to consume raw milk. Transmission of an antimicrobial-resistant mastitis pathogen and/or foodborne pathogen to humans could occur

  5. Antimicrobial peptides in the brain.

    Science.gov (United States)

    Su, Yanhua; Zhang, Kai; Schluesener, Hermann J

    2010-10-01

    Antimicrobial peptides (AMPs) are an evolutionarily conserved component of the innate immune system of many species. The brain is an immunologically privileged organ but can produce a robust immune response against pathogens and cell debris, promoting rapid and efficient clearance. AMPs may be critically involved in the innate immune system of the brain. Though the mechanisms of AMPs' action in the brain still need further elucidation, many studies have shown that AMPs are multifunctional molecules in the brain. In addition to antimicrobial action, they take part in congenital and adaptive immune reactions (immunoregulation), function as signaling molecules in tissue repair, inflammation and other important processes through different mechanisms, and they might, in addition, become diagnostic markers of brain disease.

  6. Antimicrobial stewardship in wound care

    DEFF Research Database (Denmark)

    Lipsky, Benjamin A; Dryden, Matthew; Gottrup, Finn

    2016-01-01

    of experts in infectious diseases/clinical microbiology (from the British Society for Antimicrobial Chemotherapy) and wound management (from the European Wound Management Association) who, after thoroughly reviewing the available literature and holding teleconferences, jointly produced this guidance document...... be as narrowly focused, and administered for the shortest duration, as possible. AMS teams should be interdisciplinary, especially including specialists in infection and pharmacy, with input from administrative personnel, the treating clinicians and their patients. CONCLUSIONS: Available evidence is limited...

  7. Antimicrobial resistance: a global response.

    OpenAIRE

    Smith, R.; Coast, J.

    2002-01-01

    Resistance to antimicrobial therapies reduces the effectiveness of these drugs, leading to increased morbidity, mortality, and health care expenditure. Because globalization increases the vulnerability of any country to diseases occurring in other countries, resistance presents a major threat to global public health, and no country acting on its own can adequately protect the health of its population against it. International collective action is therefore essential. Nevertheless, responsibil...

  8. APD: the Antimicrobial Peptide Database

    OpenAIRE

    Wang, Zhe; Wang, Guangshun

    2004-01-01

    An antimicrobial peptide database (APD) has been established based on an extensive literature search. It contains detailed information for 525 peptides (498 antibacterial, 155 antifungal, 28 antiviral and 18 antitumor). APD provides interactive interfaces for peptide query, prediction and design. It also provides statistical data for a select group of or all the peptides in the database. Peptide information can be searched using keywords such as peptide name, ID, length, net charge, hydrophob...

  9. Durable and Rechargeable Antimicrobial Textiles

    Science.gov (United States)

    2013-12-01

    artificial weathering exposure apparatus employing fluorescent UV lamps as a light source and using water spray for wetting will be used to simulate real in...ammonium and N-halamines. His major research interest is the application of N-halamine technology in textiles, paint, coatings, and water disinfection ...surface coatings, including antimicrobial textile finishing and water disinfection .[10-17] 4. RELATIONSHIP WITH FUTURE RESEARCH OR RESEARCH AND

  10. Antimicrobial activities of squalamine mimics.

    OpenAIRE

    1997-01-01

    We investigated the antimicrobial properties of compounds with structural features that were designed to mimic those of squalamine, an antibiotic isolated from the stomach of the dogfish shark. The mimics, like squalamine, are sterol-polyamine conjugates. Unlike squalamine, the mimics were simple to prepare, at high yield, from readily available starting materials. Several squalamine mimics showed activity against gram-negative rods, gram-positive cocci including methicillin-resistant Staphyl...

  11. Antimicrobial terpenoids from Pterocarpus indicus.

    Science.gov (United States)

    Ragasa, Consolacion Y; De Luna, Roderick D; Hofilena, Joy G

    2005-06-01

    A mixture of loliolide 1 (> 85%) and paniculatadiol 2 (Pterocarpus indicus by silica gel chromatography, while the air-dried flowers afforded lupeol 3 and phytol esters 4. The structures of 1-4 were determined by NMR spectroscopy. Antimicrobial tests on a mixture of 1 and 2 indicated that it has moderate activity against Candida albicans and low activity against Pseudomonas aeruginosa, Escherichia coli, and Aspergillus niger. It was found inactive against Staphylococcus aureus, Bacillus subtilis, and Trichophyton mentagrophytes.

  12. Silver nanoparticles: A new view on mechanistic aspects on antimicrobial activity.

    Science.gov (United States)

    Durán, Nelson; Durán, Marcela; de Jesus, Marcelo Bispo; Seabra, Amedea B; Fávaro, Wagner J; Nakazato, Gerson

    2016-04-01

    Silver nanoparticles are well known potent antimicrobial agents. Although significant progresses have been achieved on the elucidation of antimicrobial mechanism of silver nanoparticles, the exact mechanism of action is still not completely known. This overview incorporates a retrospective of previous reviews published and recent original contributions on the progress of research on antimicrobial mechanisms of silver nanoparticles. The main topics discussed include release of silver nanoparticles and silver ions, cell membrane damage, DNA interaction, free radical generation, bacterial resistance and the relationship of resistance to silver ions versus resistance to silver nanoparticles. The focus of the overview is to summarize the current knowledge in the field of antibacterial activity of silver nanoparticles. The possibility that pathogenic microbes may develop resistance to silver nanoparticles is also discussed. Antibacterial effect of nanoscopic silver generated a lot of interest both in research projects and in practical applications. However, the exact mechanism is still will have to be elucidated. This overview incorporates a retrospective of previous reviews published from 2007 to 2013 and recent original contributions on the progress of research on antimicrobial mechanisms to summarize our current knowledge in the field of antibacterial activity of silver nanoparticles. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. A European study on the relationship between antimicrobial use and antimicrobial resistance

    NARCIS (Netherlands)

    Bronzwaer, SLAM; Cars, O; Buchholz, U; Molstad, S; Goettsch, W; Veldhuijzen, IK; Kool, JL; Sprenger, MJW; Degener, JE

    2002-01-01

    In Europe, antimicrobial resistance has been monitored since 1998 by the European Antimicrobial Resistance Surveillance System (EARSS). We examined the relationship between penicillin nonsusceptibility of invasive isolates of Streptococcus pneumoniae and antibiotic sales. Information was collected o

  14. Antimicrobial resistance of Staphylococcus pseudintermedius.

    Science.gov (United States)

    Kadlec, Kristina; Schwarz, Stefan

    2012-08-01

    Staphylococcus pseudintermedius, Staphylococcus intermedius and Staphylococcus delphini together comprise the S. intermedius group (SIG). Within the SIG, S. pseudintermedius represents the major pathogenic species and is involved in a wide variety of infections, mainly in dogs, but to a lesser degree also in other animal species and humans. Antimicrobial agents are commonly applied to control S. pseudintermedius infections; however, during recent years S. pseudintermedius isolates have been identified that are meticillin-resistant and have also proved to be resistant to most of the antimicrobial agents approved for veterinary applications. This review deals with the genetic basis of antimicrobial resistance properties in S. pseudintermedius and other SIG members. A summary of the known resistance genes and their association with mobile genetic elements is given, as well as an update of the known resistance-mediating mutations. These data show that, in contrast to other staphylococcal species, S. pseudintermedius seems to prefer transposon-borne resistance genes, which are then incorporated into the chromosomal DNA, over plasmid-located resistance genes.

  15. Antimicrobial hydrogels for the treatment of infection.

    Science.gov (United States)

    Veiga, Ana Salomé; Schneider, Joel P

    2013-11-01

    The increasing prevalence of microbial infections, especially those associated with impaired wound healing and biomedical implant failure has spurred the development of new materials having antimicrobial activity. Hydrogels are a class of highly hydrated material finding use in diverse medical applications such as drug delivery, tissue engineering, as wound fillers, and as implant coatings, to name a few. The biocompatible nature of many gels make them a convenient starting platform to develop selectively active antimicrobial materials. Hydrogels with antimicrobial properties can be obtained through the encapsulation or covalent immobilization of known antimicrobial agents, or the material itself can be designed to possess inherent antimicrobial activity. In this review we present an overview of antimicrobial hydrogels that have recently been developed and when possible provide a discussion relevant to their mechanism of action.

  16. Progress in antimicrobial products from endophytes and their application in the preservation of postharvest fruits and vegetables%植物内生菌抗菌活性物质及其在果蔬采后保鲜中的应用进展

    Institute of Scientific and Technical Information of China (English)

    周金伟; 周红丽; 柏连阳; 易有金; 李高阳; 夏菠; 隆丽林

    2015-01-01

    植物内生菌是寄生在植物组织中的一大类群特殊微生物,过去长期被忽略。然而越来越多的研究表明,植物内生菌是新型抗菌药物的宝贵资源,其代谢产物中存在一系列具有多样性结构的抗菌活性化合物。本文对近年来植物内生菌产生的抗菌活性物质及其抗菌效果进行了综述,简要介绍了植物内生菌在果蔬采后保鲜中的应用,同时总结了植物内生菌抗菌活性物质在当前实际研究中所遇到的问题。%Endophytes are microorganisms residing in the tissues of living plants which are relatively unstudied for a long time.However,more and more researches have proven that endophyte are precious sources of novel antimicrobial products.Presently a number of antimicrobial natural products belong to diverse structural classes have been isolated from endophytes.This review summarizes the antimicrobial products produced by endo-phytes and their antimicrobial effects.Besides,the application of endophytes in post-harvest fruits and vegeta-bles is briefly discussed.The prospects and existing problems of isolating natural products from endophytes are also discussed.

  17. Antimicrobial technology in orthopedic and spinal implants

    Science.gov (United States)

    Eltorai, Adam EM; Haglin, Jack; Perera, Sudheesha; Brea, Bielinsky A; Ruttiman, Roy; Garcia, Dioscaris R; Born, Christopher T; Daniels, Alan H

    2016-01-01

    Infections can hinder orthopedic implant function and retention. Current implant-based antimicrobial strategies largely utilize coating-based approaches in order to reduce biofilm formation and bacterial adhesion. Several emerging antimicrobial technologies that integrate a multidisciplinary combination of drug delivery systems, material science, immunology, and polymer chemistry are in development and early clinical use. This review outlines orthopedic implant antimicrobial technology, its current applications and supporting evidence, and clinically promising future directions. PMID:27335811

  18. Antimicrobial polymer films for food packaging

    Science.gov (United States)

    Concilio, S.; Piotto, S.; Sessa, L.; Iannelli, P.; Porta, A.; Calabrese, E. C.; Galdi, M. R.; Incarnato, L.

    2012-07-01

    New antimicrobial polymeric systems were realized introducing new antimicrobial azo compounds in PP and LDPE matrices. The polymeric materials containing different percentage of azo compounds were mold-casted and the obtained film were tested in vitro against Gram+ and Gram- bacteria and fungi. These results hold promise for the fabrication of bacteria-resistant polymer films by means of simple melt processing with antimicrobial azo-dyes.

  19. Insect inducible antimicrobial peptides and their applications.

    Science.gov (United States)

    Ezzati-Tabrizi, Reyhaneh; Farrokhi, Naser; Talaei-Hassanloui, Reza; Alavi, Seyed Mehdi; Hosseininaveh, Vahid

    2013-12-01

    Antimicrobial peptides (AMPs) are found as important components of the innate immune system (host defense) of all invertebrates. These peptides can be constitutively expressed or induced in response to microbial infections. Indeed, they vary in their amino acid sequences, potency and antimicrobial activity spectra. The smaller AMPs act greatly by disrupting the structure or function of microbial cell membranes. Here, the insect innate immune system with emphasis on inducible antimicrobial peptide properties against microbial invaders has been discussed.

  20. Peptide design for antimicrobial and immunomodulatory applications.

    Science.gov (United States)

    Haney, Evan F; Hancock, Robert E W

    2013-11-01

    The increasing threat of antibiotic resistance in pathogenic bacteria and the dwindling supply of antibiotics available to combat these infections poses a significant threat to human health throughout the world. Antimicrobial peptides (AMPs) have long been touted as the next generation of antibiotics capable of filling the anti-infective void. Unfortunately, peptide-based antibiotics have yet to realize their potential as novel pharmaceuticals, in spite of the immense number of known AMP sequences and our improved understanding of their antibacterial mechanism of action. Recently, the immunomodulatory properties of certain AMPs have become appreciated. The ability of small synthetic peptides to protect against infection in vivo has demonstrated that modulation of the innate immune response is an effective strategy to further develop peptides as novel anti-infectives. This review focuses on the screening methods that have been used to assess novel peptide sequences for their antibacterial and immunomodulatory properties. It will also examine how we have progressed in our ability to identify and optimize peptides with desired biological characteristics and enhanced therapeutic potential. In addition, the current challenges to the development of peptides as anti-infectives are examined and the strategies being used to overcome these issues are discussed.

  1. Antimicrobial activity of Gymnema sylvestre leaf extract.

    Science.gov (United States)

    Satdive, R K; Abhilash, P; Fulzele, Devanand P

    2003-12-01

    The ethanolic extract of Gymnema sylvestre leaves demonstrated antimicrobial activity against Bacillus pumilis, B. subtilis, Pseudomonas aeruginosa and Staphylococcus aureus and inactivity against Proteus vulgaris and Escherichia coli.

  2. Synthesis of Aminolaurylpyridinium Chloride as Antimicrobial Agent

    Institute of Scientific and Technical Information of China (English)

    ZHAO Tao; SONG Xin-yuan; SUN Gang

    2008-01-01

    4-amino-laurylpyridinium chloride (ALPC) was synthesized and employed in antimicrobial finishing of wool fabrics. The structures of the salt was fully characterized by using FTIR, 1 H-NMR and 13 C-NMR analysis. The effects of pH conditions of finishing baths, finishing time and temperature, and salt concentrations were investigated. ALPC could form ionic interactions with anionic groups on wool, which contribute to durable antimicrobial functions. The finished wool fabrics exhibited antimicrobial efficacy against Escherichia coli. The washing durability of antimicrobial functions on the finished wool fabrics was also studied.

  3. Antimicrobial use in food and companion animals.

    Science.gov (United States)

    Prescott, John F

    2008-12-01

    The vast literature on antimicrobial drug use in animals has expanded considerably recently as the antimicrobial resistance (AMR) crisis in human medicine leads to questions about all usage of antimicrobial drugs, including long-term usage in intensively managed food animals for growth promotion and disease prevention. Attention is also increasingly focusing on antimicrobial use and on bacterial resistance in companion animals, which are in intimate contact with the human population. They may share resistant bacteria with their owners, amplify resistant bacteria acquired from their owners, and act as a reservoir for human infection. Considerable effort is being made to describe the basis of AMR in bacterial pathogens of animals. Documentation of many aspects of use of antimicrobials in animals is, however, generally less developed and only a few countries can describe quantities of drugs used in animals to kg levels annually. In recent years, many national veterinary associations have produced 'prudent use guidelines' to try to improve antimicrobial drug use and decrease resistance, but the impact of guidelines is unknown. Within the evolving global movement for 'antimicrobial stewardship', there is considerable scope to improve many aspects of antimicrobial use in animals, including infection control and reduction of use, with a view to reducing resistance and its spread, and to preserving antimicrobial drugs for the future.

  4. Antimicrobial drugs for treating cholera

    Science.gov (United States)

    Leibovici-Weissman, Ya'ara; Neuberger, Ami; Bitterman, Roni; Sinclair, David; Salam, Mohammed Abdus; Paul, Mical

    2014-01-01

    Background Cholera is an acute watery diarrhoea caused by infection with the bacterium Vibrio cholerae, which if severe can cause rapid dehydration and death. Effective management requires early diagnosis and rehydration using oral rehydration salts or intravenous fluids. In this review, we evaluate the additional benefits of treating cholera with antimicrobial drugs. Objectives To quantify the benefit of antimicrobial treatment for patients with cholera, and determine whether there are differences between classes of antimicrobials or dosing schedules. Search methods We searched the Cochrane Infectious Disease Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; African Index Medicus; LILACS; Science Citation Index; metaRegister of Controlled Trials; WHO International Clinical Trials Registry Platform; conference proceedings; and reference lists to March 2014. Selection criteria Randomized and quasi-randomized controlled clinical trials in adults and children with cholera that compared: 1) any antimicrobial treatment with placebo or no treatment; 2) different antimicrobials head-to-head; or 3) different dosing schedules or different durations of treatment with the same antimicrobial. Data collection and analysis Two reviewers independently applied inclusion and exclusion criteria, and extracted data from included trials. Diarrhoea duration and stool volume were defined as primary outcomes. We calculated mean difference (MD) or ratio of means (ROM) for continuous outcomes, with 95% confidence intervals (CI), and pooled data using a random-effects meta-analysis. The quality of evidence was assessed using the GRADE approach. Main results Thirty-nine trials were included in this review with 4623 participants. Antimicrobials versus placebo or no treatment Overall, antimicrobial therapy shortened the mean duration of diarrhoea by about a day and a half compared to placebo or no treatment (MD -36.77 hours, 95% CI -43

  5. Presence of antimicrobial resistance and antimicrobial use in sows are risk factors for antimicrobial resistance in their offspring.

    Science.gov (United States)

    Callens, Bénédicte; Faes, Christel; Maes, Dominiek; Catry, Boudewijn; Boyen, Filip; Francoys, Delphine; de Jong, Ellen; Haesebrouck, Freddy; Dewulf, Jeroen

    2015-02-01

    This study investigated whether antimicrobial-resistant Escherichia coli in apparently healthy sows and antimicrobial administration to sows and piglets influenced antimicrobial resistance in fecal commensal E. coli from piglets. Sixty sows from three herds and three of their piglets were sampled at several time points. Antimicrobial usage data during parturition and farrowing were collected. Clinical resistance was determined for two isolates per sampling time point for sows and piglets using disk diffusion. Only 27.4% of E. coli isolates from newborn piglets showed no resistance. Resistance to one or two antimicrobial classes equaled 41.2% and 46.8% in isolates from sows and piglets, respectively, for the overall farrowing period. Multiresistance to at least four classes was found as frequently in sows (15.6%) as in piglets (15.2%). Antimicrobial resistance in piglets was influenced by antimicrobial use in sows and piglets and by the sow resistance level (p≤0.05). Using aminopenicillins and third-generation cephalosporins in piglets affected resistance levels in piglets (odds ratios [OR] >1; p≤0.05). Using enrofloxacin in piglets increased the odds for enrofloxacin resistance in piglets (OR=26.78; p≤0.0001) and sows at weaning (OR=4.04; p≤0.05). For sows, antimicrobial exposure to lincomycin-spectinomycin around parturition increased the resistance to ampicillin, streptomycin, trimethoprim-sulfadiazine in sows (OR=21.33, OR=142.74, OR=18.03; p≤0.05) and additionally to enrofloxacin in piglets (OR=7.50; p≤0.05). This study demonstrates that antimicrobial use in sows and piglets is a risk factor for antimicrobial resistance in the respective animals. Moreover, resistance determinants in E. coli from piglets are selected by using antimicrobials in their dam around parturition.

  6. Decoupling internalization, acidification and phagosomal-endosomal/lysosomal fusion during phagocytosis of InlA coated beads in epithelial cells.

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    Craig D Blanchette

    Full Text Available BACKGROUND: Phagocytosis has been extensively examined in 'professional' phagocytic cells using pH sensitive dyes. However, in many of the previous studies, a separation between the end of internalization, beginning of acidification and completion of phagosomal-endosomal/lysosomal fusion was not clearly established. In addition, very little work has been done to systematically examine phagosomal maturation in 'non-professional' phagocytic cells. Therefore, in this study, we developed a simple method to measure and decouple particle internalization, phagosomal acidification and phagosomal-endosomal/lysosomal fusion in Madin-Darby Canine Kidney (MDCK and Caco-2 epithelial cells. METHODOLOGY/PRINCIPAL FINDINGS: Our method was developed using a pathogen mimetic system consisting of polystyrene beads coated with Internalin A (InlA, a membrane surface protein from Listeria monocytogenes known to trigger receptor-mediated phagocytosis. We were able to independently measure the rates of internalization, phagosomal acidification and phagosomal-endosomal/lysosomal fusion in epithelial cells by combining the InlA-coated beads (InlA-beads with antibody quenching, a pH sensitive dye and an endosomal/lysosomal dye. By performing these independent measurements under identical experimental conditions, we were able to decouple the three processes and establish time scales for each. In a separate set of experiments, we exploited the phagosomal acidification process to demonstrate an additional, real-time method for tracking bead binding, internalization and phagosomal acidification. CONCLUSIONS/SIGNIFICANCE: Using this method, we found that the time scales for internalization, phagosomal acidification and phagosomal-endosomal/lysosomal fusion ranged from 23-32 min, 3-4 min and 74-120 min, respectively, for MDCK and Caco-2 epithelial cells. Both the static and real-time methods developed here are expected to be readily and broadly applicable, as they simply

  7. Fine tuning inflammation at the front door: macrophage complement receptor 3-mediates phagocytosis and immune suppression for Francisella tularensis.

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    Shipan Dai

    2013-01-01

    Full Text Available Complement receptor 3 (CR3, CD11b/CD18 is a major macrophage phagocytic receptor. The biochemical pathways through which CR3 regulates immunologic responses have not been fully characterized. Francisella tularensis is a remarkably infectious, facultative intracellular pathogen of macrophages that causes tularemia. Early evasion of the host immune response contributes to the virulence of F. tularensis and CR3 is an important receptor for its phagocytosis. Here we confirm that efficient attachment and uptake of the highly virulent Type A F. tularensis spp. tularensis strain Schu S4 by human monocyte-derived macrophages (hMDMs requires complement C3 opsonization and CR3. However, despite a>40-fold increase in uptake following C3 opsonization, Schu S4 induces limited pro-inflammatory cytokine production compared with non-opsonized Schu S4 and the low virulent F. novicida. This suggests that engagement of CR3 by opsonized Schu S4 contributes specifically to the immune suppression during and shortly following phagocytosis which we demonstrate by CD11b siRNA knockdown in hMDMs. This immune suppression is concomitant with early inhibition of ERK1/2, p38 MAPK and NF-κB activation. Furthermore, TLR2 siRNA knockdown shows that pro-inflammatory cytokine production and MAPK activation in response to non-opsonized Schu S4 depends on TLR2 signaling providing evidence that CR3-TLR2 crosstalk mediates immune suppression for opsonized Schu S4. Deletion of the CD11b cytoplasmic tail reverses the CR3-mediated decrease in ERK and p38 activation during opsonized Schu-S4 infection. The CR3-mediated signaling pathway involved in this immune suppression includes Lyn kinase and Akt activation, and increased MKP-1, which limits TLR2-mediated pro-inflammatory responses. These data indicate that while the highly virulent F. tularensis uses CR3 for efficient uptake, optimal engagement of this receptor down-regulates TLR2-dependent pro-inflammatory responses by inhibiting

  8. Butyrate enhances disease resistance of chickens by inducing antimicrobial host defense peptide gene expression.

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    Lakshmi T Sunkara

    Full Text Available Host defense peptides (HDPs constitute a large group of natural broad-spectrum antimicrobials and an important first line of immunity in virtually all forms of life. Specific augmentation of synthesis of endogenous HDPs may represent a promising antibiotic-alternative approach to disease control. In this study, we tested the hypothesis that exogenous administration of butyrate, a major type of short-chain fatty acids derived from bacterial fermentation of undigested dietary fiber, is capable of inducing HDPs and enhancing disease resistance in chickens. We have found that butyrate is a potent inducer of several, but not all, chicken HDPs in HD11 macrophages as well as in primary monocytes, bone marrow cells, and jejuna and cecal explants. In addition, butyrate treatment enhanced the antibacterial activity of chicken monocytes against Salmonella enteritidis, with a minimum impact on inflammatory cytokine production, phagocytosis, and oxidative burst capacities of the cells. Furthermore, feed supplementation with 0.1% butyrate led to a significant increase in HDP gene expression in the intestinal tract of chickens. More importantly, such a feeding strategy resulted in a nearly 10-fold reduction in the bacterial titer in the cecum following experimental infections with S. enteritidis. Collectively, the results indicated that butyrate-induced synthesis of endogenous HDPs is a phylogenetically conserved mechanism of innate host defense shared by mammals and aves, and that dietary supplementation of butyrate has potential for further development as a convenient antibiotic-alternative strategy to enhance host innate immunity and disease resistance.

  9. Evaluation of Oxidative Metabolism in Leukocytes during Phagocytosis of Escherichia coli Carrying Genetic Constructs soxS::lux or katG::lux.

    Science.gov (United States)

    Karimov, I F; Deryabin, D G; Karimova, D N; Subbotina, T Yu; Manukhov, I V

    2016-06-01

    We studied ROS generation by human peripheral blood monocytes and granulocytes during phagocytosis of Escherichia coli soxS::lux or katG::lux responding by luminescence (bioluminescence) to the development of oxidative stress. Initially high sensitivity of the bioluminescent reaction of E. coli katG::lux strain to the effects of model ROS (KO2 and H2O2) and pronounced induction of luminescence upon contact with granulocytes, whereas E. coli soxS::lux demonstrated less pronounced reaction to chemical oxidants and bioluminescence was observed primarily upon contact with monocytes. A correlation was found between quantitative characteristics of E. coli katG::lux bioluminescence and luminol-dependent chemiluminescence of leukocytes in some patients, but no dependence of this kind was noted for E. coli soxS::lux. The results can provide experimental substantiation of a new approach for evaluation of ROS production by leukocytes during phagocytosis and choosing the optimal object for these studies.

  10. Participatory eHealth development to support nurses in antimicrobial stewardship

    NARCIS (Netherlands)

    Wentzel, Jobke; van Velsen, Lex; van Limburg, Maarten; de Jong, Nienke; Karreman, Joyce; Hendrix, Ron; van Gemert-Pi, Julia Elisabeth Wilhelmina Cornelia

    2014-01-01

    Background: Antimicrobial resistance poses a threat to patient safety worldwide. To stop antimicrobial resistance, Antimicrobial Stewardship Programs (ASPs; programs for optimizing antimicrobial use), need to be implemented. Within these programs, nurses are important actors, as they put antimicrobi

  11. The influence of bovine neutrophils on in vitro phagocytosis and killing of Staphylococcus aureus in heifers supplemented with selenium and vitamin E

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    Chalong Wachirapakorn

    2007-05-01

    Full Text Available An experiment was performed to determine the influence of bovine nutrophils on in vitro phagocytosis and killing of Staphylococcus aureus after selenium (Se, selenium yeast and vitamin E (vit E wassupplemented in heifers. Twelve healthycrossbred 75% Holstein-Friesian x Sahiwal heifers were divided into 4 groups in a 2x2 factorial arrangement in CRD. Heifers were supplemented organic selenium (seleniumyeast and vitamin E powder. The treatments were as follows; treatment 1 3 mg Se 2,000 IU vit E /hd/d (3Se2E, treatment 2 3 mg Se 4,000 IUvit E/hd/d (3Se 4E, treatment 3 6 mg Se 2,000 IU vit E/hd/d (6Se2E,and treatment 4 6 mg Se 4,000 IU vit E/hd/d (6Se 4E. The experiment comprised 3 periods: pre-supplementation (8 days, supplementation (8 days and post-supplementation (8 days periods. All heiferswere offered concentrate (15% CP at 4 kg/hd/d and rice straw hay ad libitum. Blood neutrophils were isolated from each heifer. Phagocytosis was determined by direct ingested count and killing of S. aureus byNBT reducting test. Phagocytosis and killing of S. aureus had a greater non-specific immune response during the supplementation period than in the pre-supplementation period in all treatments (P<0.05. Supplementationof 3Se4E resulted in a greater number of white blood cells (54,900 cells/cu.mm and neutrophils (11,398 cells/cu.mm. and improved phagocytosis (85% and killing of S. aureus (47% as compared to the pre-supplementation period.

  12. [Agglutination and phagocytosis of foreign abiotic particles by bluebottle Calliphora vicina haemocytes in vivo. II. Influence of the previous septic immune induction on haemocytic activity].

    Science.gov (United States)

    Kind, T V

    2010-01-01

    The rate of Calliphora vicina haemocytic defense reaction to foreign particles injection depends on the larval age and on the previous bacterial immunization. Immunization of crop-empting larvae induces an evident increase in particles phagocytosis by juvenile plasmatocytes in 24 h after injection. Both the hemogram and the pattern of cellular defense reaction change significantly after crop-empting. Immunized larvae start intensive adhesion of foreign particles to plasmatocytes surface and formation of great aggregations of plasmatocytes (morules) no longer than in 34 min after injection. The period of particle-haemocyte adhesion is short-termed and no more than after 30 min cell aggregates dissociate and adhered charcoal particles pass to thrombocydoidal agglutinates. Unimmunized control larvae of the same age have shown no adhesion and morules formation. In immunized wadering and diapausing larvae, formation of capsules consisting of central thrombocydoidal agglutinate filled with alien particles and adherent plasmatocytes I is intensified. In contrast to moru-les, this capsule formation is not accompanied by charcoal particles adhesion to plasmatocytes. Immunization of mature larvae of C. vicina shown no prominent influence on both the rate of phagocytosis and the hyaline cells differentiation. It might be supposed that the receptors system is complex and the immunization both the mechanisms of foreigners recognition (adhesion, morulation and incapsulation) and the far more lately occurring phagocytosis.

  13. Intravital imaging reveals improved Kupffer cell-mediated phagocytosis as a mode of action of glycoengineered anti-CD20 antibodies

    Science.gov (United States)

    Grandjean, Capucine L.; Montalvao, Fabricio; Celli, Susanna; Michonneau, David; Breart, Beatrice; Garcia, Zacarias; Perro, Mario; Freytag, Olivier; Gerdes, Christian A.; Bousso, Philippe

    2016-01-01

    Anti-CD20 monoclonal antibodies (mAbs) represent an effective treatment for a number of B cell malignancies and autoimmune disorders. Glycoengineering of anti-CD20mAb may contribute to increased anti-tumor efficacy through enhanced antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADP) as reported by in vitro studies. However, where and how glycoengineered Ab may potentiate therapeutic responses in vivo is yet to be elucidated. Here, we have performed mouse liver transplants to demonstrate that the liver is sufficient to mediate systemic B cells depletion after anti-CD20 treatment. Relying on intravital two-photon imaging of human CD20-expressing mice, we provide evidence that ADP by Kupffer cells (KC) is a major mechanism for rituximab-mediated B cell depletion. Notably, a glycoengineered anti-mouse CD20 Ab but not its wild-type counterpart triggered potent KC-mediated B cell depletion at low doses. Finally, distinct thresholds for KC phagocytosis were also observed for GA101 (obinutuzumab), a humanized glycoengineered type II anti-CD20 Ab and rituximab. Thus, we propose that enhanced phagocytosis of circulating B cells by KC represents an important in vivo mechanism underlying the improved activity of glycoengineered anti-CD20 mAbs. PMID:27698437

  14. Intravital imaging reveals improved Kupffer cell-mediated phagocytosis as a mode of action of glycoengineered anti-CD20 antibodies.

    Science.gov (United States)

    Grandjean, Capucine L; Montalvao, Fabricio; Celli, Susanna; Michonneau, David; Breart, Beatrice; Garcia, Zacarias; Perro, Mario; Freytag, Olivier; Gerdes, Christian A; Bousso, Philippe

    2016-10-04

    Anti-CD20 monoclonal antibodies (mAbs) represent an effective treatment for a number of B cell malignancies and autoimmune disorders. Glycoengineering of anti-CD20mAb may contribute to increased anti-tumor efficacy through enhanced antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADP) as reported by in vitro studies. However, where and how glycoengineered Ab may potentiate therapeutic responses in vivo is yet to be elucidated. Here, we have performed mouse liver transplants to demonstrate that the liver is sufficient to mediate systemic B cells depletion after anti-CD20 treatment. Relying on intravital two-photon imaging of human CD20-expressing mice, we provide evidence that ADP by Kupffer cells (KC) is a major mechanism for rituximab-mediated B cell depletion. Notably, a glycoengineered anti-mouse CD20 Ab but not its wild-type counterpart triggered potent KC-mediated B cell depletion at low doses. Finally, distinct thresholds for KC phagocytosis were also observed for GA101 (obinutuzumab), a humanized glycoengineered type II anti-CD20 Ab and rituximab. Thus, we propose that enhanced phagocytosis of circulating B cells by KC represents an important in vivo mechanism underlying the improved activity of glycoengineered anti-CD20 mAbs.

  15. Antimicrobial use in swine production and its effect on the swine gut microbiota and antimicrobial resistance.

    Science.gov (United States)

    Holman, Devin B; Chénier, Martin R

    2015-11-01

    Antimicrobials have been used in swine production at subtherapeutic levels since the early 1950s to increase feed efficiency and promote growth. In North America, a number of antimicrobials are available for use in swine. However, the continuous administration of subtherapeutic, low concentrations of antimicrobials to pigs also provides selective pressure for antimicrobial-resistant bacteria and resistance determinants. For this reason, subtherapeutic antimicrobial use in livestock remains a source of controversy and concern. The swine gut microbiota demonstrates a number of changes in response to antimicrobial administration depending on the dosage, duration of treatment, age of the pigs, and gut location that is sampled. Both culture-independent and -dependent studies have also shown that the swine gut microbiota contains a large number of antimicrobial resistance determinants even in the absence of antimicrobial exposure. Heavy metals, such as zinc and copper, which are often added at relatively high doses to swine feed, may also play a role in maintaining antimicrobial resistance and in the stability of the swine gut microbiota. This review focuses on the use of antimicrobials in swine production, with an emphasis on the North American regulatory context, and their effect on the swine gut microbiota and on antimicrobial resistance determinants in the gut microbiota.

  16. Antimicrobial resistance in Dschang, Cameroon

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    Fusi-Ngwa Catherine Kesah

    2013-01-01

    Full Text Available Background: Health-care-associated and community infections remain problematic in most of Africa where the increasing incidences of diseases, wars, poverty, malnutrition, and general environmental deterioration have led to the gradual collapse of the health-care system. Detection of antimicrobial resistance (AMR remains imperative for the surveillance purposes and optimal management of infectious diseases. This study reports the status of AMR in pathogens in Dschang. Materials and Methods: From May 2009 to March 2010, the clinical specimens collected at two hospitals were processed accorded to the standard procedures. Antibiotic testing was performed by E test, and antimycotics by disc-agar diffusion, as recommended by the Clinical and Laboratory Standards Institute on pathogens comprising Staphylococcus aureus (100 strains, Enterococcus faecalis (35, Klebsiella pneumoniae (75, Escherichia coli (50, Proteus mirabilis (30, Pseudomonas aruginosa (50, Acinetobacter species (20, and Candida albicans (150 against common antimicrobials. Results: There was no vancomycin resistance in the cocci, the minimum inhibitory concentration for 90% of these strains MIC 90 was 3 μg/ml, methicillin-resistant S. aureus (MRSA was 43%, benzyl penicillin 89% resistance in S. aureus as opposed to 5.7% in E. faecalis. Low resistance (<10% was recorded to cefoxitin, cefotaxime, and nalidixic acid (MIC 90 3-8 μg/ml against the coliforms, and to ticarcillin, aztreonam, imipenem, gentamicin, and ciprofloxacin among the non-enterobacteria; tetracycline, amoxicillin, piperacillin, and chloramphenicol were generally ineffective. Resistance rates to fluconazole, clotrimazole, econazole, and miconazole were <55% against C. albicans. The pathogens tested exhibited multidrug-resistance. Conclusion: The present findings were intended to support antimicrobial stewardship endeavors and empiric therapy. The past, present, and the future investigations in drug efficacy will continue

  17. Antimicrobial edible films and coatings.

    Science.gov (United States)

    Cagri, Arzu; Ustunol, Zeynep; Ryser, Elliot T

    2004-04-01

    Increasing consumer demand for microbiologically safer foods, greater convenience, smaller packages, and longer product shelf life is forcing the industry to develop new food-processing, cooking, handling, and packaging strategies. Nonfluid ready-to-eat foods are frequently exposed to postprocess surface contamination, leading to a reduction in shelf life. The food industry has at its disposal a wide range of nonedible polypropylene- and polyethylene-based packaging materials and various biodegradable protein- and polysaccharide-based edible films that can potentially serve as packaging materials. Research on the use of edible films as packaging materials continues because of the potential for these films to enhance food quality, food safety, and product shelf life. Besides acting as a barrier against mass diffusion (moisture, gases, and volatiles), edible films can serve as carriers for a wide range of food additives, including flavoring agents, antioxidants, vitamins, and colorants. When antimicrobial agents such as benzoic acid, sorbic acid, propionic acid, lactic acid, nisin, and lysozyme have been incorporated into edible films, such films retarded surface growth of bacteria, yeasts, and molds on a wide range of products, including meats and cheeses. Various antimicrobial edible films have been developed to minimize growth of spoilage and pathogenic microorganisms, including Listeria monocytogenes, which may contaminate the surface of cooked ready-to-eat foods after processing. Here, we review the various types of protein-based (wheat gluten, collagen, corn zein, soy, casein, and whey protein), polysaccharide-based (cellulose, chitosan, alginate, starch, pectin, and dextrin), and lipid-based (waxes, acylglycerols, and fatty acids) edible films and a wide range of antimicrobial agents that have been or could potentially be incorporated into such films during manufacture to enhance the safety and shelf life of ready-to-eat foods.

  18. Antimicrobial and biofilm inhibiting diketopiperazines.

    Science.gov (United States)

    de Carvalho, M P; Abraham, W-R

    2012-01-01

    Diketopiperazines are the smallest cyclic peptides known. 90% of Gram-negative bacteria produce diketopiperazines and they have also been isolated from Gram-positive bacteria, fungi and higher organisms. Biosynthesis of cyclodipeptides can be achieved by dedicated nonribosomal peptide synthetases or by a novel type of synthetases named cyclopeptide synthases. Since the first report in 1924 a large number of bioactive diketopiperazines was discovered spanning activities as antitumor, antiviral, antifungal, antibacterial, antiprion, antihyperglycemic or glycosidase inhibitor agents. As infections are of increasing concern for human health and resistances against existing antibiotics are growing this review focuses on the antimicrobial activities of diketopiperazines. The antibiotic bicyclomycin is a diketopiperazine and structure activity studies revealed the unique nature of this compound which was finally developed for clinical applications. The antimicrobial activities of a number of other diketopiperazines along with structure activity relationships are discussed. Here a special focus is on the activity-toxicity problem of many compounds setting tight limitations to their application as drugs. Not only these classical antimicrobial activities but also proposed action in modulating bacterial communication as a new target to control biofilms will be evaluated. Pathogens organized in biofilms are difficult to eradicate because of the increase of their tolerance for antibiotics for several orders. Diketopiperazines were reported to modulate LuxR-mediated quorum-sensing systems of bacteria, and they are considered to influence cell-cell signaling offering alternative ways of biofilm control by interfering with microbial communication. Concluding the review we will finally discuss the potential of diketopiperazines in the clinic to erase biofilm infections.

  19. Human B cells have an active phagocytic capability and undergo immune activation upon phagocytosis of Mycobacterium tuberculosis.

    Science.gov (United States)

    Zhu, Qi; Zhang, Min; Shi, Ming; Liu, Yang; Zhao, Qing; Wang, Wenjing; Zhang, Guangyun; Yang, Longxiu; Zhi, Jin; Zhang, Lin; Hu, Gengyao; Chen, Pin; Yang, Yining; Dai, Wen; Liu, Tingting; He, Ying; Feng, Guodong; Zhao, Gang

    2016-04-01

    The paradigm that B cells are nonphagocytic was taken for granted for a long time until phagocytic B cells were found in early vertebrate animals. Thereafter, limited evidence has shown that human B cells may also internalize bacteria. However, whether human B cells can actively phagocytose bacteria has been less extensively investigated; in particular, the mechanisms and significance of the phagocytosis require clarification. Here, we show that the human Raji B cell line can phagocytose both live and dead Mycobacterium tuberculosis (Mtb), and the phagocytosed Mtb in turn affects the immune functions of the B cells. After incubation of Raji cells with Mtb, our confocal microscopy, electron microscopy and flow cytometry data showed that Raji cells effectively engulfed Mtb as well as latex beads. The phagocytic rate was proportional to the incubation time and the amount of Mtb or beads added. Additionally, we found that normal human serum could enhance the ability of Raji cells to phagocytose Mtb, while heat-inactivated serum reversed this promoting effect. The phagocytic process of B cells could partially be inhibited by cytochalasin B, an actin inhibitor. Importantly, the phagocytosed Mtb could regulate B cell immune functions, such as stimulating IgM production and upregulating the expression of the antigen-presenting costimulatory molecules CD80 and CD86. Therefore, our results provide the first evidence that human B cells can phagocytose Mtb in an active manner that is independent of bacterial viability, and phagocytosed Mtb can in turn regulate the immune activation of B cells.

  20. Minocycline attenuates Aβ oligomers-induced pro-inflammatory phenotype in primary microglia while enhancing Aβ fibrils phagocytosis.

    Science.gov (United States)

    El-Shimy, Ismail Amr; Heikal, Ola Ahmed; Hamdi, Nabila

    2015-11-16

    Microglia, the brain innate immune cells, are activated in response to amyloid beta (Aβ) resulting in neuroinflammation in AD brains. Recently, two phenotypes have been described for microglia: the pro-inflammatory classical and the anti-inflammatory alternative. Changes in microglia phenotype that control their phagocytic function are yet to be determined. The highly neurotoxic Aβ oligomers (oAβ) formed at an early disease stage induce pro-inflammatory microglia activation releasing neurotoxic mediators and contributing to neurodegeneration. A novel strategy for AD treatment is to attenuate microglia-induced inflammation while maintaining efficient Aβ clearance. Minocycline effectively crosses the blood-brain barrier and has widely reported neuroprotective effects. Yet, its exact mechanism of neuroprotection and its effects on microglia are still unknown. The aim of this study is to investigate the effect of minocycline on the phagocytic uptake of fAβ by primary microglia in relation to their activation state in an inflammatory milieu generated by oAβ or LPS. The study shows that minocycline is able to attenuate oAβ-induced neuroinflammatory response of microglia by inhibiting their pro-inflammatory phenotype activation. In addition, a significant enhancement of fAβ phagocytosis by minocycline- treated microglia is reported for the first time, providing novel insight into its neuroprotective role in AD.

  1. Phagocytosis of Picornavirus-Infected Cells Induces an RNA-Dependent Antiviral State in Human Dendritic Cells▿

    Science.gov (United States)

    Kramer, Matthijs; Schulte, Barbara M.; Toonen, Liza W. J.; Barral, Paola M.; Fisher, Paul B.; Lanke, Kjerstin H. W.; Galama, Jochem M. D.; van Kuppeveld, Frank J. M.; Adema, Gosse J.

    2008-01-01

    Dendritic cells (DCs) play a central role in instructing antiviral immune responses. DCs, however, can become targeted by different viruses themselves. We recently demonstrated that human DCs can be productively infected with echoviruses (EVs), but not coxsackie B viruses (CVBs), both of which are RNA viruses belonging to the Enterovirus genus of the Picornaviridae family. We now show that phagocytosis of CVB-infected, type I interferon-deficient cells induces an antiviral state in human DCs. Uptake of infected cells increased the expression of the cytoplasmic RNA helicases retinoic acid-inducible gene I and melanoma differentiation-associated gene 5 as well as other interferon-stimulated genes and protected DCs against subsequent infection with EV9. These effects depended on recognition of viral RNA and could be mimicked by exposure to the synthetic double-stranded RNA analogue poly(I:C) but not other Toll-like receptor (TLR) ligands. Blocking endosomal acidification abrogated protection, suggesting a role for TLRs in the acquisition of an antiviral state in DCs. In conclusion, recognition of viral RNA rapidly induces an antiviral state in human DCs. This might provide a mechanism by which DCs protect themselves against viruses when attracted to an environment with ongoing infection. PMID:18184700

  2. Negative correlation between mycological surfaces pollution in hospital emergency departments and blood monocytes phagocytosis of healthcare workers.

    Science.gov (United States)

    Lewicki, Sławomir; Bielawska-Drózd, Agata; Winnicka, Izabela; Leszczyński, Paweł; Cieślik, Piotr; Korniłłowicz-Kowalska, Teresa; Bohacz, Justyna; Jaroszuk-Ściseł, Jolanta; Skopińska-Różewska, Ewa; Kocik, Janusz

    2015-01-01

    The aim of the present study was to find a possible relationship between the presence of yeast and filamentous fungi in hospital emergency departments and the activity levels of blood granulocytes and monocytes in emergency personnel. The study of mycological pollution was conducted in winter; the samples were collected from 10 Warsaw hospitals emergency departments (HE D) and in 10 control locations (office spaces) and included air samples and swabbing of floor and walls. The blood for immunological investigation was taken in spring, from 40 men, 26 to 53 years old, healthcare workers of these departments, who have been working for at least 5 years in their current positions, and from 36 corresponding controls, working in control offices. Evaluation of blood leukocyte subpopulations was done by hematological analyzer and cytometry analysis and monocyte and granulocyte phagocytosis by Phagotest. There were no significant differences in the level of mycological contamination between the test and control places. The qualitative analysis of the surfaces and air samples revealed a prevalence of strains belonging to Aspergillus spp. and Penicillium spp. genus. Statistical analysis revealed the existence of negative correlation between the number of phagocytizing blood monocytes and fungi spores content on floor and wall surfaces in hospital emergency departments (r = -0.3282, p correlation between the number of phagocytizing monocytes in the blood of office workers and fungi pollution of control offices (r = 0.4421, p < 0.01).

  3. Sialoglycoproteins in morphological distinct stages of Mucor polymorphosporus and their influence on phagocytosis by human blood phagocytes.

    Science.gov (United States)

    Almeida, Catia Amancio; de Campos-Takaki, Galba Maria; Portela, Maristela Barbosa; Travassos, Luiz R; Alviano, Celuta Sales; Alviano, Daniela Sales

    2013-10-01

    The possible role of sialic acids in host cells-fungi interaction and their association with glycoproteins were evaluated using a clinical isolate of the dimorphic fungus Mucor polymorphosporus. Lectin-binding assays with spores and yeast cells denoted the presence of surface sialoglycoconjugates containing 2,3- and 2,6-linked sialylglycosyl groups. Western blotting with peroxidase-labeled Limulus polyphemus agglutinin revealed the occurrence of different sialoglycoprotein types in both cell lysates and cell wall protein extracts of mycelia, spores, and yeasts of M. polymorphosporus. Sialic acids contributed to the surface negative charge of spores and yeast forms as evaluated by adherence to a cationic substrate. Sialidase-treated spores were less resistant to phagocytosis by human neutrophils and monocytes from healthy individuals than control (untreated) fungal suspensions. The results suggest that sialic acids are terminal units of various glycoproteins of M. polymorphosporus, contributing to negative charge of yeasts and spore cells and protecting infectious propagules from destruction by host cells.

  4. Asbestos-induced endothelial cell activation and injury. Demonstration of fiber phagocytosis and oxidant-dependent toxicity.

    Science.gov (United States)

    Garcia, J G; Gray, L D; Dodson, R F; Callahan, K S

    1988-10-01

    Vascular endothelial cell injury is important in the development of a variety of chronic interstitial lung disorders. However, the involvement of such injury in the inflammatory response associated with the inhalation of asbestos fibers is unclear and the mechanism of asbestos fiber cytotoxicity remains unknown. In the present study, human umbilical vein endothelial cells were challenged with amosite asbestos and several parameters of cellular function were examined. Electron microscopic examination revealed that endothelial cell exposure to asbestos resulted in active phagocytosis of these particulates. Biochemical evidence of dose-dependent asbestos-mediated endothelial cell activation was indicated by increased metabolism of arachidonic acid. For example, amosite asbestos (500 micrograms/ml) produced a ninefold increase in prostacyclin (PGI2) levels over those levels in non-exposed cells. Incubation of human endothelial cells with asbestos fibers induced specific 51Cr release in both a dose- and time-dependent fashion indicative of cellular injury. Injury induced by amosite asbestos was not significantly attenuated by treatment of the endothelial cell monolayer with either the iron chelator deferoxamine, which prevents hydroxyl radical (.OH) formation, or by the superoxide anion (O2-) scavenger, superoxide dismutase. However, significant dose-dependent protection was observed with the hydrogen peroxide (H2O2) scavenger, catalase. Chelation of elemental iron present within amosite asbestos fibers by deferoxamine produced a 33% reduction in asbestos cytotoxicity, suggesting a potential role for hydroxyl radical-mediated injury via the iron-catalyzed Haber-Weiss reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. [Comparative study of intramacrophagic penetration and action on phagocytosis of a macrolide (spiramycin) and a fluoroquinolone (pefloxacin)].

    Science.gov (United States)

    Desnottes, J F; Diallo, N

    1990-04-01

    Antibiotic-phagocyte interaction is an important parameter involved in the elimination process of intracellular bacteria. The aim of the present study was to compare, using the same model, the phagocytic uptake and the intracellular activity of a macrolide and a quinolone. Accumulation of spiramycin and pefloxacin by guinea pig peritoneal macrophages (GPpM) was studied by means of a velocity-gradient centrifugation technique and expression of the ratio of the cellular concentration of antibiotic to the extracellular concentration (IC-EC). Three aspects of Staphylococcus aureus (209-P) phagocytosis were studied: 1) the phagocytic capacity (PC), mean number of ingested cocci by GpPM; 2) the phagocytic activity (PA), percentage of phagocyting GpPM with at least one bacterium; 3) the number of intracellular viable bacteria (IVB). Phagocytic capacity and phagocytic activity were determined by fluorescence microscopy using S. aureus stained with acridine orange. Intracellular viable bacteria were quantified by standard colony counts (CFU). The ratios of intracellular to extracellular concentration of pefloxacin and spiramycin are respectively 9 and 23. Pretreatment of guinea-pig peritoneal macrophages with 10 mg/l of each antibiotic does not modify phagocytic capacity and phagocytic activity, but lead to a decrease of intracellular viable bacteria. S. aureus pretreatment with 1/4 the MIC of each antibiotic increased phagocytic capacity and phagocytic activity and decrease intracellular viable bacteria (especially spiramycin).(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Time-controlled phagocytosis of asymmetric liposomes: Application to phosphatidylserine immunoliposomes binding HIV-1 virus-like particles.

    Science.gov (United States)

    Petazzi, Roberto Arturo; Gramatica, Andrea; Herrmann, Andreas; Chiantia, Salvatore

    2015-11-01

    Macrophage immune functions such as antibody-mediated phagocytosis are strongly impaired in individuals affected by HIV-1. Nevertheless, infected macrophages are still able to phagocytose apoptotic cells. For this reason, we recently developed antibody-decorated phosphatidylserine (PS)-containing liposomes that bind HIV-1 virus-like particles and, by mimicking apoptotic cells, are efficiently internalized by macrophages. In the context of an in vivo application, it would be extremely important to initially protect immunoliposomes from macrophages, in order to provide enough time to redistribute through the body and achieve maximum virus binding. To this end, we have designed asymmetric immunoliposomes in which the PS is initially confined to the inner leaflet and thus cannot be recognized by macrophages. Spontaneous PS flip-flop to the outer surface leads to a time-delay in internalization by macrophages in vitro. Such a delay can be fine-tuned by altering the molecular composition of the immunoliposomes. In the fight against HIV-1, macrophage plays an important role. Ironically, the phagocytic functions of these cells are often impaired by HIV-1. In this interesting article, the authors described the development of asymmetric liposomes, which would bind HIV-1 with prolonged systemic circulation, such that the clearance of virus by macrophages is enhanced. This system represents a promising effective approach to utilize the phagocytic capability of macrophages. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Antimicrobial Activities of Dorema Auchri

    Directory of Open Access Journals (Sweden)

    A Sharifi

    2011-01-01

    Full Text Available Introduction & Objective: Due to emerging of resistance of microorganisms to antibiotics, investigations for novel antimicrobial agents have always been one of the major preoccupations of the medical society. Traditional medicine systems have played an important role during human evolution and development. Today, a number of medical herbs around the world have been studied for their medicinal activities. Amongst the several herbal medicine used as a medicine, Dorema auchri is yet another potent herbal medicine which has not been extensively studied for the medicinal uses in comparison with other herbal medicine. Dorema auchri has a long history of use as a sore and food additive in Yasuj, Iran. However, not much scientific work has been conducted on Dorema auchri antimicrobial activities. The present study aimed to study the antimicrobial properties of Dorema auchri on some pathogen microorganisms. Materials & Methods: In the present study was conducted at Yasuj University of Medical Sciences in 2009. After collection and preparation of hydro alcoholic extract of Dorena auchri, the extract was used to study its activities against human pathogen microorganisms (overall 10 microorganisms. The determination of minimal inhibitory concentration (MIC and minimum lethal concentration were evaluated for this extract. The antimicrobial potent of Dorema auchri extract was compared with commercial antibiotics. Each experiment was done three times and collected data were analyzed by SPSS using ANOVA and Chi-Square tests. Results: Findings of this study showed that in 10 mg/ml concentration, all bacteria were resistant to Dorema auchri extract. In 20 mg/ml concentration, only Staphylococcus areus and Staphylococcus epidermis showed zone of inhibition (ZOI 10 mm and 13 mm respectively. In 40 mg/ml concentration, the maximum ZOI was 15 mm in Staphylococcus areus and 80 mg/ml concentration, the maximum ZOI was 20 mm in Staphylococcus areus. The acceptable MIC

  8. Antimicrobial evaluation of mangiferin analogues

    Directory of Open Access Journals (Sweden)

    Singh S

    2009-01-01

    Full Text Available The naturally occurring xanthone glycoside mangiferin has been isolated by column chromatography from the ethanol extract of stem bark of Mangifera indica. Mangiferin was further converted to 5-(N-phenylaminomethylenomangiferin, 5-(N-p-chlorophenylaminomethyleno mangiferin, 5-(N-2-methylphenylaminomethyleno mangiferin, 5-(N-p-methoxyphenylaminomethyleno mangiferin, 5-(N,N-diphenylaminomethyleno mangiferin, 5-(N--napthylaminomethyleno mangiferin and 5-(N-4-methylphenylaminomethyleno mangiferin. Mangiferin and its analogues were characterized by melting point and R f value determination and through spectral technique like UV, IR, and NMR spectral analysis. The synthesized compounds were screened for antimicrobial activity.

  9. Antimicrobial Evaluation of Mangiferin Analogues

    Science.gov (United States)

    Singh, S. K.; Kumar, Y.; Kumar, S. Sadish; Sharma, V. K.; Dua, K.; Samad, A.

    2009-01-01

    The naturally occurring xanthone glycoside mangiferin has been isolated by column chromatography from the ethanol extract of stem bark of Mangifera indica. Mangiferin was further converted to 5-(N-phenylaminomethyleno)mangiferin, 5-(N-p-chlorophenylaminomethyleno) mangiferin, 5-(N-2-methylphenylaminomethyleno) mangiferin, 5-(N-p-methoxyphenylaminomethyleno) mangiferin, 5-(N, N-diphenylaminomethyleno) mangiferin, 5-(N--napthylaminomethyleno) mangiferin and 5-(N-4-methylphenylaminomethyleno) mangiferin. Mangiferin and its analogues were characterized by melting point and Rf value determination and through spectral technique like UV, IR, and NMR spectral analysis. The synthesized compounds were screened for antimicrobial activity. PMID:20490307

  10. [Antimicrobial sensitive of Morganella morganii].

    Science.gov (United States)

    Zalas-Wiecek, Patrycja; Michalska, Anna; Sielska, Barbara; Gospodarek, Eugenia

    2011-01-01

    The aim of this study was the evaluation of the antimicrobial sensitive of Morganella morganii rods isolated from clinical samples. This study included 50 of M. morganii strains isolated in the Clinical Microbiology Department of dr. A. Jurasz University Hospital in 2008-2009. All of strains were sensitive to carbapenems (imipenem, meropenem, ertapenem, doripenem) and piperacillin/tazobactam and most of them to beta-lactam antibiotics, aminoglycosides and fluorochinolons. Resistance to tetracyclines demonstrated 38,0% strains and to doxycycline - 40,0%. One out of 6 strains isolated from urine samples were sensitive to nitrofurantoin. Extended Spectrum Beta-Lactamases were produced by 5 (10,0%) strains.

  11. Antimicrobial activity of some Alnus species.

    Science.gov (United States)

    Altınyay, Ç; Eryılmaz, M; Yazgan, A N; Sever Yılmaz, B; Altun, M L

    2015-12-01

    The increasing prevalence of resistant microorganisms forced scientists to find new antimicrobial substances from different sources like medicinal plants. The aim of this study was to determine the antimicrobial activities of leaf extracts of some Alnus sp. against some bacteria and a yeast. Aqueous and ethanolic leaf extracts of A. glutinosa subsp. glutinosa, A. orientalis var. orientalis, A. orientalis var. pubescens were screened for their antimicrobial activities against Staphylococcus aureus ATCC 25923, S. aureus ATCC 43300 (MRSA), Bacillus subtilis ATCC 6633, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Candida albicans ATCC 10231. Broth dilution method was used to determine the antimicrobial activities of plant extracts. Ethanolic extracts of tested species exhibited better antimicrobial activity than aqueous extracts. Ethanolic extracts of tested species possessed activity having MIC values of 0.125-0.250 mg/ml against the tested microorganisms. No antibacterial activity was observed against B. subtilis, E. coli, P. aeruginosa for all the aqueous extracts. Except these aqueous extracts, the others possessed activity having MIC value of 1.000 mg/ml against the tested microorganisms. To our knowledge, this is the first investigation on the evaluation of antimicrobial activities on aqueous and ethanolic leaf extracts of these species. This study provides significant information about antimicrobial activities of leaf extracts of A. glutinosa subsp. glutinosa, A. orientalis var. orientalis, A. orientalis var. pubescens. It is conceivable that one of the reason for the usage of Alnus glutinosa, in treatment of wound healing in folk medicine, is because of its antimicrobial activity.

  12. Antimicrobial peptides in innate immune responses

    DEFF Research Database (Denmark)

    Sorensen, O.E.; Borregaard, N.; Cole, A.M.

    2008-01-01

    Antimicrobial peptides (AMPs) are ancient effector molecules in the innate immune response of eukaryotes. These peptides are important for the antimicrobial efficacy of phagocytes and for the innate immune response mounted by epithelia of humans and other mammals. AMPs are generated either by de ...

  13. [Antimicrobial activity of Calendula L. plants].

    Science.gov (United States)

    Radioza, S A; Iurchak, L D

    2007-01-01

    The sap of different organs of genus Calendula plant species has been studied for antimicrobial activity. The sap of racemes demonstrated the most expressed antimicrobial effect while that of the roots - the least one. Calendula species inhibited all tested pathogenic microorganisms, especially Pseudomonas syringae, P. fluorescens, Xanthomonas campestris, Agrobacterium tumefaciens. Calendula suffruticosa was the most active to all investigated microorganisms.

  14. Synthesis and antimicrobial activity of squalamine analogue.

    Science.gov (United States)

    Kim, H S; Choi, B S; Kwon, K C; Lee, S O; Kwak, H J; Lee, C H

    2000-08-01

    Synthesis and antimicrobial activity of squalamine analogue 2 are reported. The synthesis of 2 was accomplished from bisnoralcohol 3. The spermidine moiety was introduced via reductive amination of an appropriately functionalized 3beta-aminosterol with spermidinyl aldehyde 17 utilizing sodium triacetoxyborohydride as the reducing agent. Compound 2 shows weaker antimicrobial activity than squalamine.

  15. Antimicrobial food packaging: potential and pitfalls

    Science.gov (United States)

    Malhotra, Bhanu; Keshwani, Anu; Kharkwal, Harsha

    2015-01-01

    Nowadays food preservation, quality maintenance, and safety are major growing concerns of the food industry. It is evident that over time consumers’ demand for natural and safe food products with stringent regulations to prevent food-borne infectious diseases. Antimicrobial packaging which is thought to be a subset of active packaging and controlled release packaging is one such promising technology which effectively impregnates the antimicrobial into the food packaging film material and subsequently delivers it over the stipulated period of time to kill the pathogenic microorganisms affecting food products thereby increasing the shelf life to severe folds. This paper presents a picture of the recent research on antimicrobial agents that are aimed at enhancing and improving food quality and safety by reduction of pathogen growth and extension of shelf life, in a form of a comprehensive review. Examination of the available antimicrobial packaging technologies is also presented along with their significant impact on food safety. This article entails various antimicrobial agents for commercial applications, as well as the difference between the use of antimicrobials under laboratory scale and real time applications. Development of resistance amongst microorganisms is considered as a future implication of antimicrobials with an aim to come up with actual efficacies in extension of shelf life as well as reduction in bacterial growth through the upcoming and promising use of antimicrobials in food packaging for the forthcoming research down the line. PMID:26136740

  16. Antimicrobial resistance issues in beef production

    Science.gov (United States)

    Antimicrobial resistance threats to human health as identified have been recognized as a critical global public health concern. Linkage of some threats to beef production is discussed. The relevance to beef production of recent government actions will be examined. Prominent antimicrobial resistance ...

  17. Cationic Antimicrobial Polymers and Their Assemblies

    Directory of Open Access Journals (Sweden)

    Ana Maria Carmona-Ribeiro

    2013-05-01

    Full Text Available Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs. The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications.

  18. Antimicrobial Activity of a Cationic Guanidine Compound against Two Pathogenic Oral Bacteria

    Directory of Open Access Journals (Sweden)

    E. Escamilla-García

    2017-01-01

    Full Text Available This study evaluated the potential antimicrobial properties of a polyguanidine (CatDex on two oral bacteria. Chlorhexidine gluconate 1340 μmoL L−1 (CHX 0.12% was used as control. Streptococcus mutans (S. mutans and Porphyromonas gingivalis (P. gingivalis were grown in BHI media. Bacterial sensitivity and antimicrobial activity were determined by the minimum inhibitory concentration (MIC and Kirby-Bauer methods. To study side effects, that is, toxicity, dental pulp stem cells (DPSCs were used. Fluorometric cytotoxicity and confocal microscopy assays were used in order to test cell viability. CatDex inhibited growth of S. mutans at all concentrations and growth of P. gingivalis at all concentrations except 25 μmoL L−1. The MIC of CatDex was 50 μmoL L−1 for both S. mutans and P. gingivalis. The inhibition of bacteria exposed for 8 h at 50 μmoL L−1 of CatDex exhibited increased antimicrobial activity over time, with 91% inhibition in both bacteria. The antimicrobial activities of CatDex and CHX were similar when tested on two common bacteria. CatDex was significantly less toxic to DPSCs. CatDex toxicity depended on time and not on concentration. With regard to clinical relevance, CatDex may have potential as a novel antimicrobial agent. Further studies are in progress.

  19. Antimicrobial Resistance in the Intensive Care Unit: A Focus on Gram-Negative Bacterial Infections.

    Science.gov (United States)

    MacVane, Shawn H

    2017-01-01

    Bacterial infections are a frequent cause of hospitalization, and nosocomial infections are an increasingly common condition, particularly within the acute/critical care setting. Infection control practices and new antimicrobial development have primarily focused on gram-positive bacteria; however, in recent years, the incidence of infections caused by gram-negative bacteria has risen considerably in intensive care units. Infections caused by multidrug-resistant (MDR) gram-negative organisms are associated with high morbidity and mortality, with significant direct and indirect costs resulting from prolonged hospitalizations due to antibiotic treatment failures. Of particular concern is the increasing prevalence of antimicrobial resistance to β-lactam antibiotics (including carbapenems) among Pseudomonas aeruginosa and Acinetobacter baumannii and, recently, among pathogens of the Enterobacteriaceae family. Treatment options for infections caused by these pathogens are limited. Antimicrobial stewardship programs focus on optimizing the appropriate use of currently available antimicrobial agents with the goals of improving outcomes for patients with infections caused by MDR gram-negative organisms, slowing the progression of antimicrobial resistance, and reducing hospital costs. Newly approved treatment options are available, such as β-lactam/β-lactamase inhibitor combinations, which significantly extend the armamentarium against MDR gram-negative bacteria. © The Author(s) 2016.

  20. Shigatoxin encoding Bacteriophage ϕ24B modulates bacterial metabolism to raise antimicrobial tolerance

    Science.gov (United States)

    Holt, G. S.; Lodge, J. K.; McCarthy, A. J.; Graham, A. K.; Young, G.; Bridge, S. H.; Brown, A. K.; Veses-Garcia, M.; Lanyon, C. V.; Sails, A.; Allison, H. E.; Smith, D. L.

    2017-01-01

    How temperate bacteriophages play a role in microbial infection and disease progression is not fully understood. They do this in part by carrying genes that promote positive evolutionary selection for the lysogen. Using Biolog phenotype microarrays and comparative metabolite profiling we demonstrate the impact of the well-characterised Shiga toxin-prophage ϕ24B on its Escherichia coli host MC1061. As a lysogen, the prophage alters the bacterial physiology by increasing the rates of respiration and cell proliferation. This is the first reported study detailing phage-mediated control of the E. coli biotin and fatty acid synthesis that is rate limiting to cell growth. Through ϕ24B conversion the lysogen also gains increased antimicrobial tolerance to chloroxylenol and 8-hydroxyquinoline. Distinct metabolite profiles discriminate between MC1061 and the ϕ24B lysogen in standard culture, and when treated with 2 antimicrobials. This is also the first reported use of metabolite profiling to characterise the physiological impact of lysogeny under antimicrobial pressure. We propose that temperate phages do not need to carry antimicrobial resistance genes to play a significant role in tolerance to antimicrobials. PMID:28106081

  1. Application of natural antimicrobials for food preservation.

    Science.gov (United States)

    Tiwari, Brijesh K; Valdramidis, Vasilis P; O'Donnell, Colm P; Muthukumarappan, Kasiviswanathan; Bourke, Paula; Cullen, P J

    2009-07-22

    In this review, antimicrobials from a range of plant, animal, and microbial sources are reviewed along with their potential applications in food systems. Chemical and biochemical antimicrobial compounds derived from these natural sources and their activity against a range of pathogenic and spoilage microorganisms pertinent to food, together with their effects on food organoleptic properties, are outlined. Factors influencing the antimicrobial activity of such agents are discussed including extraction methods, molecular weight, and agent origin. These issues are considered in conjunction with the latest developments in the quantification of the minimum inhibitory (and noninhibitory) concentration of antimicrobials and/or their components. Natural antimicrobials can be used alone or in combination with other novel preservation technologies to facilitate the replacement of traditional approaches. Research priorities and future trends focusing on the impact of product formulation, intrinsic product parameters, and extrinsic storage parameters on the design of efficient food preservation systems are also presented.

  2. Methods of Antimicrobial Coating of Diverse Materials

    Science.gov (United States)

    Akse, James R.; Holtsnider, John T.; Kliestik, Helen

    2011-01-01

    Methods of coating diverse substrate materials with antimicrobial agents have been developed. Originally intended to reduce health risks to astronauts posed by pathogenic microorganisms that can grow on surfaces in spacecraft, these methods could also be used on Earth for example, to ensure sterility of surgical inserts and other medical equipment. The methods involve, generally, chemical preparation of substrate surfaces to enable attachment of antimicrobial molecules to the substrate surfaces via covalent bonds. Substrate materials that have been treated successfully include aluminum, glass, a corrosion-resistant nickel alloy, stainless steel, titanium, and poly(tetrafluoroethylene). Antimicrobial agents that have been successfully immobilized include antibiotics, enzymes, bacteriocins, bactericides, and fungicides. A variety of linkage chem istries were employed. Activity of antimicrobial coatings against gram-positive bacteria, gram-negative bacteria, and fungi was demonstrated. Results of investigations indicate that the most suitable combination of antimicrobial agent, substrate, and coating method depends upon the intended application.

  3. Antimicrobial Peptides: Multifunctional Drugs for Different Applications

    Directory of Open Access Journals (Sweden)

    Lea-Jessica Albrecht

    2012-02-01

    Full Text Available Antimicrobial peptides (APs are an important part of the innate immune system in epithelial and non-epithelial surfaces. So far, many different antimicrobial peptides from various families have been discovered in non-vertebrates and vertebrates. They are characterized by antibiotic, antifungal and antiviral activities against a variety of microorganisms. In addition to their role as endogenous antimicrobials, APs participate in multiple aspects of immunity. They are involved in septic and non-septic inflammation, wound repair, angiogenesis, regulation of the adaptive immune system and in maintaining homeostasis. Due to those characteristics AP could play an important role in many practical applications. Limited therapeutic efficiency of current antimicrobial agents and the emerging resistance of pathogens require alternate antimicrobial drugs. The purpose of this review is to highlight recent literature on functions and mechanisms of APs. It also shows their current practical applications as peptide therapeutics and bioactive polymers and discusses the possibilities of future clinical developments.

  4. Antimicrobial resistant bacteria in the food chain

    DEFF Research Database (Denmark)

    Wegener, Henrik Caspar

    2003-01-01

    Antimicrobials are used for treatment and prevention of disease in food animals and as feed additives for growth promotion. All uses lead to the development of resistant bacteria, some of which are pathogenic to humans. Current main concerns are with resistance in Salmonella and Campylobacter...... to fluoroquinolones, which are used for empirical treatment of diarrhea in humans. Resistance to vancomycin and Synercid((R)) in enterococci is associated with use of similar drugs as growth promoters in food animals. Danish food animal producers have terminated the use of antimicrobial growth promoters. This has...... reduced the total use of antimicrobials by more than 50% and markedly reduced levels of resistance. There is an urgent need to implement globally, WHO principles for prudent use of antimicrobials in food animals. Use of antimicrobials as growth promoters could and should be terminated completely....

  5. Antimicrobial peptides important in innate immunity.

    Science.gov (United States)

    Cederlund, Andreas; Gudmundsson, Gudmundur H; Agerberth, Birgitta

    2011-10-01

    Antimicrobial peptides are present in all walks of life, from plants to animals, and they are considered to be endogenous antibiotics. In general, antimicrobial peptides are determinants of the composition of the microbiota and they function to fend off microbes and prevent infections. Antimicrobial peptides eliminate micro-organisms through disruption of their cell membranes. Their importance in human immunity, and in health as well as disease, has only recently been appreciated. The present review provides an introduction to the field of antimicrobial peptides in general and discusses two of the major classes of mammalian antimicrobial peptides: the defensins and the cathelicidins. The review focuses on their structures, their main modes of action and their regulation.

  6. Optimizing antimicrobial therapy in critically ill patients

    Directory of Open Access Journals (Sweden)

    Vitrat V

    2014-10-01

    Full Text Available Virginie Vitrat,1 Serge Hautefeuille,2 Cécile Janssen,1 David Bougon,2 Michel Sirodot,2 Leonardo Pagani1,3 1Antimicrobial Stewardship Program, Infectious Diseases Unit, 2Intensive Care Unit, Annecy-Genevois Hospital Center (CHANGE, Annecy, France; 3Infectious Diseases Unit, Bolzano Central Hospital, Bolzano, Italy Abstract: Critically ill patients with infection in the intensive care unit (ICU would certainly benefit from timely bacterial identification and effective antimicrobial treatment. Diagnostic techniques have clearly improved in the last years and allow earlier identification of bacterial strains in some cases, but these techniques are still quite expensive and not readily available in all institutions. Moreover, the ever increasing rates of resistance to antimicrobials, especially in Gram-negative pathogens, are threatening the outcome for such patients because of the lack of effective medical treatment; ICU physicians are therefore resorting to combination therapies to overcome resistance, with the direct consequence of promoting further resistance. A more appropriate use of available antimicrobials in the ICU should be pursued, and adjustments in doses and dosing through pharmacokinetics and pharmacodynamics have recently shown promising results in improving outcomes and reducing antimicrobial resistance. The aim of multidisciplinary antimicrobial stewardship programs is to improve antimicrobial prescription, and in this review we analyze the available experiences of such programs carried out in ICUs, with emphasis on results, challenges, and pitfalls. Any effective intervention aimed at improving antibiotic usage in ICUs must be brought about at the present time; otherwise, we will face the challenge of intractable infections in critically ill patients in the near future. Keywords: ICU, antimicrobial therapies, antimicrobial stewardship, pharmacokinetics, pharmacodynamics, antimicrobial resistance, early diagnosis

  7. The safety of antimicrobial drugs

    Directory of Open Access Journals (Sweden)

    Ćupić Vitomir

    2016-01-01

    Full Text Available The discovery and introduction of antimicrobial drugs in clinical practice has been recorded as one of the greatest achievements in the history of medicine. The application of these drugs, made a big, almost revolutionary upheaval in treatment of many infectious diseases. Its significance for the humanity lies in the fact that hundreds of thousands of people, until then condemned to a certain death, has been saved now. However, it was shown that antimicrobial therapy carries some risk of possible occurrence of undesirable and toxic effects, such as direct toxic effects, development of resistance, the impact on the normal microflora or disorder of micropopulation metabolic functions in digestive tract of ruminants, unwanted interactions with other drugs, damage or necrosis of the tissue at the injection site, residues in foodstuff intended for human consumption, suppression of immune system or defense mechanisms of the body, and damage of fetal or neonatal tissue. All mentioned, directly or indirectly, to a greater or lesser degree can reduce the safety of these drugs.

  8. Antimicrobial peptide action on parasites.

    Science.gov (United States)

    Torrent, Marc; Pulido, David; Rivas, Luis; Andreu, David

    2012-08-01

    Diseases caused by protozoan parasites can pose a severe thread to human health and are behind some serious neglected tropical diseases like malaria and leishmaniasis. Though several different drugs have been developed in order to eradicate these diseases, a successful candidate has not yet been discovered. Among the most active compounds tested, antimicrobial peptides (AMPs) are particularly appealing because of their wide spectrum of action. AMPs have been described to perturb protozoan homeostasis by disrupting the cellular membranes but also by interfering with key processes in the parasite metabolism. In this review we describe the diverse mechanisms of action of AMPs on protozoan targets and how they can be exploited to treat diseases. Moreover, we describe with detail the antimicrobial action of AMPs on two major parasitical infections: leishmaniasis and malaria. All the features reviewed here show that AMPs are promising drugs to target protozoan parasites and that further understanding of the mechanism of action of these compounds will lead to improved drugs that could be worth to test in a clinical phase.

  9. Antimicrobial outcomes in plasma medicine

    Science.gov (United States)

    Ryan, Thomas P.; Stalder, Kenneth R.; Woloszko, Jean

    2015-03-01

    Plasma is referred to as the fourth state of matter and is frequently generated in the environment of a strong electric field. The result consists of highly reactive species--ions, electrons, reactive atoms and molecules, and UV radiation. Plasma Medicine unites a number of fields, including Physics, Plasma Chemistry, Cell Biology, Biochemistry, and Medicine. The treatment modality utilizes Cold Atmospheric Plasma (CAP), which is able to sterilize and treat microbes in a nonthermal manner. These gas-based plasma systems operate at close to room temperature and atmospheric pressure, making them very practical for a range of potential treatments and are highly portable for clinical use throughout the health care system. The hypothesis is that gas based plasma kills bacteria, fungus, and viruses but spares mammalian cells. This paper will review systematic work which shows examples of systems and performance in regards to antimicrobial effects and the sparing of mammalian cells. The mechanism of action will be discussed, as well as dosing for the treatment of microbial targets, including sterilization processes, another important healthcare need. In addition, commercial systems will be overviewed and compared, along with evidence-based, patient results. The range of treatments cover wound treatment and biofilms, as well as antimicrobial treatment, with little chance for resistance and tolerance, as in drug regimens. Current clinical studies include applications in dentistry, food treatment, cancer treatment, wound treatment for bacteria and biofilms, and systems to combat health care related infections.

  10. Antimicrobial resistance: cost and containment.

    Science.gov (United States)

    Coast, Joanna; Smith, Richard D

    2003-08-01

    There is growing evidence that antimicrobial resistance causes serious consequences for individuals as well as leading to increased healthcare costs. The containment of resistance is therefore a policy problem which will impact on all health systems in the next few years. Unfortunately, there is, as yet, no definitive evidence suggesting that particular control measures are successful in containing either the emergence or transmission of antimicrobial resistance. Furthermore, few studies contain information about costs and even where there is such information it is generally inadequate because of the narrow perspectives from which analyses are conducted. In part, this is due to methodological problems associated with the inclusion of cost data: measuring and valuing what are often intangible costs; identifying costs associated with organizational change; and accounting for interaction between costs at levels from the individual to the international. Good quality research, including both economic evaluation and comprehensive economic modelling, is required to determine the most cost-effective combination of strategies to pursue in combating resistance, and to find ways around these methodological difficulties.

  11. Animal venoms as antimicrobial agents.

    Science.gov (United States)

    Perumal Samy, Ramar; Stiles, Bradley G; Franco, Octavio L; Sethi, Gautam; Lim, Lina H K

    2017-06-15

    Hospitals are breeding grounds for many life-threatening bacteria worldwide. Clinically associated gram-positive bacteria such as Staphylococcus aureus/methicillin-resistant S. aureus and many others increase the risk of severe mortality and morbidity. The failure of antibiotics to kill various pathogens due to bacterial resistance highlights the urgent need to develop novel, potent, and less toxic agents from natural sources against various infectious agents. Currently, several promising classes of natural molecules from snake (terrestrial and sea), scorpion, spider, honey bee and wasp venoms hold promise as rich sources of chemotherapeutics against infectious pathogens. Interestingly, snake venom-derived synthetic peptide/snake cathelicidin not only has potent antimicrobial and wound-repair activity but is highly stable and safe. Such molecules are promising candidates for novel venom-based drugs against S. aureus infections. The structure of animal venom proteins/peptides (cysteine rich) consists of hydrophobic α-helices or β-sheets that produce lethal pores and membrane-damaging effects on bacteria. All these antimicrobial peptides are under early experimental or pre-clinical stages of development. It is therefore important to employ novel tools for the design and the development of new antibiotics from the untapped animal venoms of snake, scorpion, and spider for treating resistant pathogens. To date, snail venom toxins have shown little antibiotic potency against human pathogens. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Antimicrobial peptides in Caenorhabditis elegans

    Directory of Open Access Journals (Sweden)

    A Bogaerts

    2010-01-01

    Full Text Available The nematode Caenorhabditis elegans is one of the most successful model species for experimental research because of its sequenced genome, the versatile genetic toolkit and the straightforward breeding among others. In natural conditions however, this tiny worm is constantly surrounded by micro-organisms, simultaneously a source of indispensable nutrition and inevitable pathogens. Lacking an adaptive immune system, the worm solely relies on its innate immune defence to cope with its challenging life style. Hence C. elegans is an excellent model to gain more insight in innate immunity, which is remarkably preserved between invertebrate and vertebrate animals. The innate defence consists of receptors to detect potential pathogens, a complex network of signalling pathways and last but not least, effector molecules to abolish harmful microbes. In this review, we focus on the antimicrobial peptides, a vital subgroup of effector molecules. We summarise the current knowledge of the different families of C. elegans antimicrobial peptides, comprising NLPs, caenacins, ABFs, caenopores, and a recently discovered group with antifungal activity among which thaumatin-like proteins.

  13. Use of back-scatter electron signals to visualise cell/nanowires interactions in vitro and in vivo; frustrated phagocytosis of long fibres in macrophages and compartmentalisation in mesothelial cells in vivo

    Directory of Open Access Journals (Sweden)

    Schinwald Anja

    2012-08-01

    Full Text Available Abstract Background Frustrated phagocytosis has been stated as an important factor in the initiation of an inflammatory response after fibre exposure. The length of fibrous structures has been linked to the potential of fibres to induce adverse health effects for at least 40 years. However, we only recently reported for the first time the threshold length for fibre-induced inflammation in the pleural space and we implicated frustrated phagocytosis in the pro-inflammatory effects of long fibres. This study extends the examination of the threshold value for frustrated phagocytosis using well-defined length classes of silver nanowires (AgNW ranging from 3–28 μm and describes in detail the morphology of frustrated phagocytosis using a novel technique and also describes compartmentalisation of fibres in the pleural space. Methods A novel technique, backscatter scanning electron microscopy (BSE was used to study frustrated phagocytosis since it provides high-contrast detection of nanowires, allowing clear discrimination between the nanofibres and other cellular features. A human monocyte-derived macrophage cell line THP-1 was used to investigate cell-nanowire interaction in vitro and the parietal pleura, the site of fibre retention after inhalation exposure was chosen to visualise the cell- fibre interaction in vivo after direct pleural installation of AgNWs. Results The length cut-off value for frustrated phagocytosis differs in vitro and in vivo. While in vitro frustrated phagocytosis could be observed with fibres ≥14 μm, in vivo studies showed incomplete uptake at a fibre length of ≥10 μm. Recently we showed that inflammation in the pleural space after intrapleural injection of the same nanofibre panel occurs at a length of ≥5 μm. This onset of inflammation does not correlate with the onset of frustrated phagocytosis as shown in this study, leading to the conclusion that intermediate length fibres fully enclosed within macrophages as

  14. Progression in the study on the phagocytosis function of B lymphocyte%B淋巴细胞吞噬功能研究进展

    Institute of Scientific and Technical Information of China (English)

    高杨; 高继鑫; 刘玉峰

    2009-01-01

    以往的观点认为只有巨噬细胞、单核细胞、粒细胞和树突状细胞是专职的吞噬细胞,而B细胞作为免疫系统的抗体产生细胞,虽然能够产生特异的免疫球蛋白与抗原结合,却不具备吞噬能力.但最近的研究指出硬骨鱼类(彩虹鳟鱼)和两栖类(爪蟾)的B细胞可以吞噬颗粒抗原,首次揭示了进化上较为原始的B细胞同样具有吞噬能力.众多研究提示哺乳动物B-1 B细胞很可能具有吞噬能力.%It was accepted in the past that only these cells such as macrophage, histoleucocyte, granular cell and dendritic cell are phagocytes, while B lymphocyte has no ability to phagocytize, although it can generate specific immune globulin for antigen binding. However recent studies indicate that B lymphocyte of osteichthyes (trout) and amphibia (xenopus laevis) can phagocytize particulate antigen, these studies for the first time re-vealed that relatively archaic B lymphocyte has ability to phagocytize too. Numerous studies reveal that B-1 cell in mammalian probably has ability to phagocytize.

  15. Research progress on animal model and therapeutic effect of photodynamic antimicrobial chemotherapy in treatment of traumatic infection%光动力抗菌化学疗法治疗创伤感染的动物模型及疗效研究进展

    Institute of Scientific and Technical Information of China (English)

    袁瑶; 刘子泉(综述); 丁辉(审校)

    2016-01-01

    Due to the abuse of antibiotics, bacterial resistance has become a more and more serious problem and the treatment of wound infections are suffering more challengs, whereas photodynamic antimicrobial chemotherapy (PACT) is a promising novel strategy for the treatment of resistant bacteria. This paper reviews recent development of different animal models of traumatic infections, its characters and therapeutic efficacy of photosensitizersin vivo, which aims to provide evidence for optimal application of these models, and for parallel comparison of therapeutic efficacy of the same kind of photosensitizers or animal models.%抗生素的滥用致细菌耐药性问题日益严重,创伤感染的治疗也愈具挑战,目前针对耐药菌的治疗中光动力抗菌化学疗法(photodynamic antimicrobial chemotherapy,PACT)是一种很有发展前景的新策略。笔者就PACT在治疗创伤感染的动物模型、特点及各种光敏剂疗效进行归纳,以利于研究者选择适宜的模型工具、对同类光敏剂或动物模型的治疗疗效进行平行比较。

  16. Antimicrobial use in long-term-care facilities

    NARCIS (Netherlands)

    Nicolle, LE; Bentley, DW; Garibaldi, R; Neuhaus, EG; Smith, PW

    2000-01-01

    There is intense antimicrobial use in long-term-care facilities (LTCFs), and studies repeatedly document that much of this use is inappropriate. The current crisis in antimicrobial resistance, which encompasses the LTCF, heightens concerns of antimicrobial use. Attempts to improve antimicrobial use

  17. Antimicrobial resistance in India: A review.

    Science.gov (United States)

    Kumar, S Ganesh; Adithan, C; Harish, B N; Sujatha, S; Roy, Gautam; Malini, A

    2013-07-01

    Antimicrobial resistance is an important concern for the public health authorities at global level. However, in developing countries like India, recent hospital and some community based data showed increase in burden of antimicrobial resistance. Research related to antimicrobial use, determinants and development of antimicrobial resistance, regional variation and interventional strategies according to the existing health care situation in each country is a big challenge. This paper discusses the situational analysis of antimicrobial resistance with respect to its problem, determinants and challenges ahead with strategies required in future to reduce the burden in India. Recent data from Google search, Medline and other sources were collected which was reviewed and analyzed by the authors. Hospital based studies showed higher and varied spectrum of resistance in different regions while there are limited number of community based studies at country level. There exists lacunae in the structure and functioning of public health care delivery system with regard to quantification of the problem and various determining factors related to antimicrobial resistance. There is an urgent need to develop and strengthen antimicrobial policy, standard treatment guidelines, national plan for containment of AMR and research related to public health aspects of AMR at community and hospital level in India.

  18. The role of poverty in antimicrobial resistance.

    Science.gov (United States)

    Planta, Margaret B

    2007-01-01

    Antimicrobial resistance is a worldwide problem that has deleterious long-term effects as the development of drug resistance outpaces the development of new drugs. Poverty has been cited by the World Health Organization as a major force driving the development of antimicrobial resistance. In developing countries, factors such as inadequate access to effective drugs, unregulated dispensing and manufacture of antimicrobials, and truncated antimicrobial therapy because of cost are contributing to the development of multidrug-resistant organisms. Within the United States, poverty-driven practices such as medication-sharing, use of "leftover" antibiotics, and the purchase and use of foreign-made drugs of questionable quality are likely contributing to antimicrobial resistance. However, there is currently a dearth of studies in the United States analyzing the socioeconomic and behavioral factors behind antimicrobial resistance in United States communities. Further studies of these factors, with an emphasis on poverty-driven practices, need to be undertaken in order to fully understand the problem of antimicrobial resistance in the United States and to develop effective intervention to combat this problem.

  19. Uses of antimicrobials in plant agriculture.

    Science.gov (United States)

    Vidaver, Anne K

    2002-06-01

    Bacterial diseases of plants are less prevalent than diseases caused by fungi and viruses. Antimicrobials for prophylactic treatment of bacterial diseases of plants are limited in availability, use, and efficacy, and therapeutic use is largely ineffective. Most applications are by spray treatments in orchards. Monitoring and surveillance for drug resistance are not routinely done. In the United States, data on use of antimicrobials for treatment of bacterial diseases of plants are limited to streptomycin and oxytetracycline. Resistance to streptomycin has become widespread among bacterial phytopathogens; no resistance among these bacteria has yet been reported for oxytetracycline. No human health effects have been documented since inception of use of antimicrobials in plants in the 1950s. Transfer of antimicrobial resistance from marker genes in transgenic plants to bacteria has not been documented under natural conditions in field-grown plants. However, antimicrobial-resistance genes are being eliminated from use as marker genes because of concerns about possible transfer from plant genomes back to bacteria, with further horizontal transfer to the bacteria in the environment, or from plant genomes to animals by plant consumption. No new antimicrobials are expected to be used in plant agriculture because of high costs of development, regulatory constraints, and environmental and human health concerns. Alternatives to antimicrobials, such as biocontrol agents, transgenic plants, and novel chemicals, are being developed and marketed, although their efficacy remains to be determined.

  20. Human Antimicrobial Peptides and Proteins

    Directory of Open Access Journals (Sweden)

    Guangshun Wang

    2014-05-01

    Full Text Available As the key components of innate immunity, human host defense antimicrobial peptides and proteins (AMPs play a critical role in warding off invading microbial pathogens. In addition, AMPs can possess other biological functions such as apoptosis, wound healing, and immune modulation. This article provides an overview on the identification, activity, 3D structure, and mechanism of action of human AMPs selected from the antimicrobial peptide database. Over 100 such peptides have been identified from a variety of tissues and epithelial surfaces, including skin, eyes, ears, mouths, gut, immune, nervous and urinary systems. These peptides vary from 10 to 150 amino acids with a net charge between −3 and +20 and a hydrophobic content below 60%. The sequence diversity enables human AMPs to adopt various 3D structures and to attack pathogens by different mechanisms. While α-defensin HD-6 can self-assemble on the bacterial surface into nanonets to entangle bacteria, both HNP-1 and β-defensin hBD-3 are able to block cell wall biosynthesis by binding to lipid II. Lysozyme is well-characterized to cleave bacterial cell wall polysaccharides but can also kill bacteria by a non-catalytic mechanism. The two hydrophobic domains in the long amphipathic α-helix of human cathelicidin LL-37 lays the basis for binding and disrupting the curved anionic bacterial membrane surfaces by forming pores or via the carpet model. Furthermore, dermcidin may serve as ion channel by forming a long helix-bundle structure. In addition, the C-type lectin RegIIIα can initially recognize bacterial peptidoglycans followed by pore formation in the membrane. Finally, histatin 5 and GAPDH(2-32 can enter microbial cells to exert their effects. It appears that granulysin enters cells and kills intracellular pathogens with the aid of pore-forming perforin. This arsenal of human defense proteins not only keeps us healthy but also inspires the development of a new generation of personalized