Complement receptor expression and activation of the complement cascade on B lymphocytes from patients with systemic lupus erythematosus (SLE)

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Marquart, H V; Svendsen, A; Rasmussen, J M

1995-01-01

It has previously been reported that the expression of the complement receptors, CR1 on erythrocytes and blood leucocytes and CR2 on B cells, is reduced in patients with SLE, and that the reduced expression of CR1 on erythrocytes is related to disease activity. We have earlier demonstrated...... that normal B cells are capable of activating the alternative pathway (AP) of complement in a CR2-dependent fashion. In this study we have investigated whether disturbances in this activity may be related to the altered phenotype of SLE B cells. Flow cytometry was used to measure expression of complement...

Depletion of the Third Complement Component Ameliorates Age-Dependent Oxidative Stress and Positively Modulates Autophagic Activity in Aged Retinas in a Mouse Model

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Dorota Rogińska

2017-01-01

Full Text Available The aim of the study was to investigate the influence of complement component C3 global depletion on the biological structure and function of the aged retina. In vivo morphology (OCT, electrophysiological function (ERG, and the expression of selected oxidative stress-, apoptosis-, and autophagy-related proteins were assessed in retinas of 12-month-old C3-deficient and WT mice. Moreover, global gene expression in retinas was analyzed by RNA arrays. We found that the absence of active C3 was associated with (1 alleviation of the age-dependent decrease in retinal thickness and gradual deterioration of retinal bioelectrical function, (2 significantly higher levels of antioxidant enzymes (catalase and glutathione reductase and the antiapoptotic survivin and Mcl-1/Bak dimer, (3 lower expression of the cellular oxidative stress marker—4HNE—and decreased activity of proapoptotic caspase-3, (4 ameliorated retinal autophagic activity with localization of ubiquitinated protein conjugates commonly along the retinal pigment epithelium (RPE layer, and (5 significantly increased expression of several gene sets associated with maintenance of the physiological functions of the neural retina. Our findings shed light on mechanisms of age-related retinal alterations by identifying C3 as a potential therapeutic target for retinal aging.

Activation of the human complement system by cholesterol-rich and pegylated liposomes - Modulation of cholesterol-rich liposome-mediated complement activation by elevated serum LDL and HDL levels

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Moghimi, S.M.; Hamad, I.; Bunger, R.

2006-01-01

level of S-protein-bound form of the terminal complex (SC5b-9). However, liposome-induced rise of SC5b-9 was significantly suppressed when serum HDL cholesterol levels increased by 30%. Increase of serum LDL to levels similar to that observed in heterozygous familial hypercholesterolemia also suppressed......Intravenously infused liposomes may induce cardiopulmonary distress in some human subjects, which is a manifestation of "complement activation-related pseudoallergy." We have now examined liposome-mediated complement activation in human sera with elevated lipoprotein (LDL and HDL) levels, since...... abnormal or racial differences in serum lipid profiles seem to modulate the extent of complement activation and associated adverse responses. In accordance with our earlier observations, cholesterol-rich (45 mol% cholesterol) liposomes activated human complement, as reflected by a significant rise in serum...

The C-type lectin of the aggrecan G3 domain activates complement.

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Camilla Melin Fürst

Full Text Available Excessive complement activation contributes to joint diseases such as rheumatoid arthritis and osteoarthritis during which cartilage proteins are fragmented and released into the synovial fluid. Some of these proteins and fragments activate complement, which may sustain inflammation. The G3 domain of large cartilage proteoglycan aggrecan interacts with other extracellular matrix proteins, fibulins and tenascins, via its C-type lectin domain (CLD and has important functions in matrix organization. Fragments containing G3 domain are released during normal aggrecan turnover, but increasingly so in disease. We now show that the aggrecan CLD part of the G3 domain activates the classical and to a lesser extent the alternative pathway of complement, via binding of C1q and C3, respectively. The complement control protein (CCP domain adjacent to the CLD showed no effect on complement initiation. The binding of C1q to G3 depended on ionic interactions and was decreased in D2267N mutant G3. However, the observed complement activation was attenuated due to binding of complement inhibitor factor H to CLD and CCP domains. This was most apparent at the level of deposition of terminal complement components. Taken together our observations indicate aggrecan CLD as one factor involved in the sustained inflammation of the joint.

Rivaroxaban limits complement activation compared with warfarin in antiphospholipid syndrome patients with venous thromboembolism.

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Arachchillage, D R J; Mackie, I J; Efthymiou, M; Chitolie, A; Hunt, B J; Isenberg, D A; Khamashta, M; Machin, S J; Cohen, H

2016-11-01

Essentials Complement activation has a pathogenic role in thrombotic antiphospholipid syndrome (APS). Coagulation proteases such as factor Xa can activate complement proteins. Complement activation markers were elevated in anticoagulated thrombotic APS patients. Complement activation decreased in APS patients switching from warfarin to rivaroxaban. Background Complement activation may play a major role in the pathogenesis of thrombotic antiphospholipid syndrome (APS). Coagulation proteases such as factor Xa can activate complement proteins. Aims To establish whether rivaroxaban, a direct factor Xa inhibitor, limits complement activation compared with warfarin in APS patients with previous venous thromboembolism (VTE). Methods A total of 111 APS patients with previous VTE, on warfarin target INR 2.5, had blood samples taken at baseline and at day 42 after randomization in the RAPS (Rivaroxaban in Antiphospholipid Syndrome) trial. Fifty-six patients remained on warfarin and 55 switched to rivaroxaban. Fifty-five normal controls (NC) were also studied. Markers of complement activation (C3a, C5a, terminal complement complex [SC5b-9] and Bb fragment) were assessed. Results APS patients had significantly higher complement activation markers compared with NC at both time-points irrespective of the anticoagulant. There were no differences between the two patient groups at baseline, or patients remaining on warfarin at day 42. In 55 patients randomized to rivaroxaban, C3a, C5a and SC5b-9 were lower at day 42 (median (ng mL -1 ) [confidence interval] 64 [29-125] vs. 83 [35-147], 9 [2-15] vs. 12 [4-18] and 171 [56-245] vs. 201 [66-350], respectively) but levels of Bb fragment were unchanged. There were no correlations between rivaroxaban levels and complement activation markers. Conclusions APS patients with previous VTE on warfarin exhibit increased complement activation, which is likely to occur via the classical pathway and is decreased by rivaroxaban administration

Classical Complement Pathway Activation in the Kidneys of Women With Preeclampsia.

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Penning, Marlies; Chua, Jamie S; van Kooten, Cees; Zandbergen, Malu; Buurma, Aletta; Schutte, Joke; Bruijn, Jan Anthonie; Khankin, Eliyahu V; Bloemenkamp, Kitty; Karumanchi, S Ananth; Baelde, Hans

2015-07-01

A growing body of evidence suggests that complement dysregulation plays a role in the pathogenesis of preeclampsia. The kidney is one of the major organs affected in preeclampsia. Because the kidney is highly susceptible to complement activation, we hypothesized that preeclampsia is associated with renal complement activation. We performed a nationwide search for renal autopsy material in the Netherlands using a computerized database (PALGA). Renal tissue was obtained from 11 women with preeclampsia, 25 pregnant controls, and 14 nonpregnant controls with hypertension. The samples were immunostained for C4d, C1q, mannose-binding lectin, properdin, C3d, C5b-9, IgA, IgG, and IgM. Preeclampsia was significantly associated with renal C4d-a stable marker of complement activation-and the classical pathway marker C1q. In addition, the prevalence of IgM was significantly higher in the kidneys of the preeclamptic women. No other complement markers studied differed between the groups. Our findings in human samples were validated using a soluble fms-like tyrosine kinase 1 mouse model of preeclampsia. The kidneys in the soluble fms-like tyrosine kinase 1-injected mice had significantly more C4 deposits than the control mice. The association between preeclampsia and renal C4d, C1q, and IgM levels suggests that the classical complement pathway is involved in the renal injury in preeclampsia. Moreover, our finding that soluble fms-like tyrosine kinase 1-injected mice develop excess C4 deposits indicates that angiogenic dysregulation may play a role in complement activation within the kidney. We suggest that inhibiting complement activation may be beneficial for preventing the renal manifestations of preeclampsia. © 2015 American Heart Association, Inc.

The Role of Properdin in Zymosan- and Escherichia coli-Induced Complement Activation

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Harboe, Morten; Garred, Peter; Lindstad, Julie K

2012-01-01

Properdin is well known as an enhancer of the alternative complement amplification loop when C3 is activated, whereas its role as a recognition molecule of exogenous pathogen-associated molecular patterns and initiator of complement activation is less understood. We therefore studied the role...... of properdin in activation of complement in normal human serum by zymosan and various Escherichia coli strains. In ELISA, microtiter plates coated with zymosan induced efficient complement activation with deposition of C4b and terminal complement complex on the solid phase. Virtually no deposition of C4b...... cytometry was used to further explore whether properdin acts as an initial recognition molecule reacting directly with zymosan and three E. coli strains. Experiments reported by other authors were made with EGTA Mg(2+) buffer, permitting autoactivation of C3. We found inhibition by compstatin...

The stability of complement-mediated bactericidal activity in human serum against Salmonella.

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Colette M O'Shaughnessy

Full Text Available The complement cascade includes heat-labile proteins and care is required when handling serum in order to preserve its functional integrity. We have previously used a whole human serum bactericidal assay to show that antibody and an intact complement system are required in blood for killing of invasive isolates of Salmonella. The aim of the present study was to evaluate the conditions under which human serum can be stored and manipulated while maintaining complement integrity. Serum bactericidal activity against Salmonella was maintained for a minimum of 35 days when stored at 4°C, eight days at 22°C and 54 hours at 37°C. Up to three freeze-thaw cycles had no effect on the persistence of bactericidal activity and hemolytic complement assays confirmed no effect on complement function. Delay in the separation of serum for up to four days from clotted blood stored at 22°C did not affect bactericidal activity. Dilution of serum resulted in an increased rate of loss of bactericidal activity and so serum should be stored undiluted. These findings indicate that the current guidelines concerning manipulation and storage of human serum to preserve complement integrity and function leave a large margin for safety with regards to bactericidal activity against Salmonella. The study provides a scheme for determining the requirements for serum handling in relation to functional activity of complement in other systems.

Hepatitis C virus NS3/4A protease inhibits complement activation by cleaving complement component 4.

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Seiichi Mawatari

Full Text Available BACKGROUND: It has been hypothesized that persistent hepatitis C virus (HCV infection is mediated in part by viral proteins that abrogate the host immune response, including the complement system, but the precise mechanisms are not well understood. We investigated whether HCV proteins are involved in the fragmentation of complement component 4 (C4, composed of subunits C4α, C4β, and C4γ, and the role of HCV proteins in complement activation. METHODS: Human C4 was incubated with HCV nonstructural (NS 3/4A protease, core, or NS5. Samples were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and then subjected to peptide sequencing. The activity of the classical complement pathway was examined using an erythrocyte hemolysis assay. The cleavage pattern of C4 in NS3/4A-expressing and HCV-infected cells, respectively, was also examined. RESULTS: HCV NS3/4A protease cleaved C4γ in a concentration-dependent manner, but viral core and NS5 did not. A specific inhibitor of NS3/4A protease reduced C4γ cleavage. NS3/4A protease-mediated cleavage of C4 inhibited classical pathway activation, which was abrogated by a NS3/4A protease inhibitor. In addition, co-transfection of cells with C4 and wild-type NS3/4A, but not a catalytic-site mutant of NS3/4A, produced cleaved C4γ fragments. Such C4 processing, with a concomitant reduction in levels of full-length C4γ, was also observed in HCV-infected cells expressing C4. CONCLUSIONS: C4 is a novel cellular substrate of the HCV NS3/4A protease. Understanding disturbances in the complement system mediated by NS3/4A protease may provide new insights into the mechanisms underlying persistent HCV infection.

Complement activation in the Parkinson's disease substantia nigra: an immunocytochemical study

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Conant Stephanie B

2006-10-01

Full Text Available Abstract Background Inflammatory processes are increased in the Parkinson's disease (PD brain. The long-term use of nonsteroidal anti-inflammatory drugs has been associated, in retrospective studies, with decreased risk for PD, suggesting that inflammation may contribute to development of this disorder. The objective of this study was to determine the extent of complement activation, a major inflammatory mechanism, in PD. Methods Substantia nigra specimens from young normal subjects (n = 11–13, aged normal subjects (n = 24–28, and subjects with PD (n = 19–20, Alzheimer's disease (AD; n = 12–13, and dementia with Lewy bodies (DLB; n = 9 were stained for iC3b and C9, representing early- and late-stage complement activation, respectively. Numbers of iC3b+, C9+, and total melanized neurons in each section were counted in a blinded fashion. Nonparametric analyses were used to evaluate differences between groups and to evaluate correlations between complement staining, numbers of melanized neurons, and the duration of PD. Results Lewy bodies in both PD and DLB specimens stained for iC3b and C9. Staining was also prominent on melanized neurons. The percentage of iC3b+ neurons was significantly increased in PD vs. aged normal and AD specimens, and in young normal vs. aged normal specimens. C9 immunoreactivity was significantly increased in PD vs. AD specimens, but unlike iC3b, the increased C9 staining in PD and young normal specimens did not achieve statistical significance vs. aged normal specimens. iC3b and C9 staining in PD specimens was not correlated with the numbers of remaining melanized neurons, nor with the duration of PD. Conclusion Complement activation occurs on Lewy bodies and melanized neurons in the PD substantia nigra. Early complement activation (iC3b is increased on melanized neurons in PD vs. aged normal specimens, and late-stage complement activation (C9 also tends to increase. This latter finding suggests that complement

Guinea pig complement potently measures vibriocidal activity of human antibodies in response to cholera vaccines.

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Kim, Kyoung Whun; Jeong, Soyoung; Ahn, Ki Bum; Yang, Jae Seung; Yun, Cheol-Heui; Han, Seung Hyun

2017-12-01

The vibriocidal assay using guinea pig complement is widely used for the evaluation of immune responses to cholera vaccines in human clinical trials. However, it is unclear why guinea pig complement has been used over human complement in the measurement of vibriocidal activity of human sera and there have not been comparison studies for the use of guinea pig complement over those from other species. Therefore, we comparatively investigated the effects of complements derived from human, guinea pig, rabbit, and sheep on vibriocidal activity. Complements from guinea pig, rabbit, and human showed concentration-dependent vibriocidal activity in the presence of quality control serum antibodies. Of these complements, guinea pig complement was the most sensitive and effective over a wide concentration range. When the vibriocidal activity of complements was measured in the absence of serum antibodies, human, sheep, and guinea pig complements showed vibriocidal activity up to 40-fold, 20-fold, and 1-fold dilution, respectively. For human pre- and post-vaccination sera, the most potent vibriocidal activity was observed when guinea pig complement was used. In addition, the highest fold-increases between pre- and post- vaccinated sera were obtained with guinea pig complement. Furthermore, human complement contained a higher amount of V. cholerae- and its lipopolysaccharide-specific antibodies than guinea pig complement. Collectively, these results suggest that guinea pig complements are suitable for vibriocidal assays due to their high sensitivity and effectiveness to human sera.

Micrurus snake venoms activate human complement system and generate anaphylatoxins

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Tanaka Gabriela D

2012-01-01

Full Text Available Abstract Background The genus Micrurus, coral snakes (Serpentes, Elapidae, comprises more than 120 species and subspecies distributed from the south United States to the south of South America. Micrurus snake bites can cause death by muscle paralysis and further respiratory arrest within a few hours after envenomation. Clinical observations show mainly neurotoxic symptoms, although other biological activities have also been experimentally observed, including cardiotoxicity, hemolysis, edema and myotoxicity. Results In the present study we have investigated the action of venoms from seven species of snakes from the genus Micrurus on the complement system in in vitro studies. Several of the Micrurus species could consume the classical and/or the lectin pathways, but not the alternative pathway, and C3a, C4a and C5a were generated in sera treated with the venoms as result of this complement activation. Micrurus venoms were also able to directly cleave the α chain of the component C3, but not of the C4, which was inhibited by 1,10 Phenanthroline, suggesting the presence of a C3α chain specific metalloprotease in Micrurus spp venoms. Furthermore, complement activation was in part associated with the cleavage of C1-Inhibitor by protease(s present in the venoms, which disrupts complement activation control. Conclusion Micrurus venoms can activate the complement system, generating a significant amount of anaphylatoxins, which may assist due to their vasodilatory effects, to enhance the spreading of other venom components during the envenomation process.

Detection and characterisation of Complement protein activity in bovine milk by bactericidal sequestration assay.

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Maye, Susan; Stanton, Catherine; Fitzgerald, Gerald F; Kelly, Philip M

2015-08-01

While the Complement protein system in human milk is well characterised, there is little information on its presence and activity in bovine milk. Complement forms part of the innate immune system, hence the importance of its contribution during milk ingestion to the overall defences of the neonate. A bactericidal sequestration assay, featuring a Complement sensitive strain, Escherichia coli 0111, originally used to characterise Complement activity in human milk was successfully applied to freshly drawn bovine milk samples, thus, providing an opportunity to compare Complement activities in both human and bovine milks. Although not identical in response, the levels of Complement activity in bovine milk were found to be closely comparable with that of human milk. Differential counts of Esch. coli 0111 after 2 h incubation were 6.20 and 6.06 log CFU/ml, for raw bovine and human milks, respectively - the lower value representing a stronger Complement response. Exposing bovine milk to a range of thermal treatments e.g. 42, 45, 65, 72, 85 or 95 °C for 10 min, progressively inhibited Complement activity by increasing temperature, thus confirming the heat labile nature of this immune protein system. Low level Complement activity was found, however, in 65 and 72 °C heat treated samples and in retailed pasteurised milk which highlights the outer limit to which high temperature, short time (HTST) industrial thermal processes should be applied if retention of activity is a priority. Concentration of Complement in the fat phase was evident following cream separation, and this was also reflected in the further loss of activity recorded in low fat variants of retailed pasteurised milk. Laboratory-based churning of the cream during simulated buttermaking generated an aqueous (buttermilk) phase with higher levels of Complement activity than the fat phase, thus pointing to a likely association with the milk fat globule membrane (MFGM) layer.

The Emerging Role of Complement Lectin Pathway in Trypanosomatids: Molecular Bases in Activation, Genetic Deficiencies, Susceptibility to Infection, and Complement System-Based Therapeutics

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Ingrid Evans-Osses

2013-01-01

Full Text Available The innate immune system is evolutionary and ancient and is the pivotal line of the host defense system to protect against invading pathogens and abnormal self-derived components. Cellular and molecular components are involved in recognition and effector mechanisms for a successful innate immune response. The complement lectin pathway (CLP was discovered in 1990. These new components at the complement world are very efficient. Mannan-binding lectin (MBL and ficolin not only recognize many molecular patterns of pathogens rapidly to activate complement but also display several strategies to evade innate immunity. Many studies have shown a relation between the deficit of complement factors and susceptibility to infection. The recently discovered CLP was shown to be important in host defense against protozoan microbes. Although the recognition of pathogen-associated molecular patterns by MBL and Ficolins reveal efficient complement activations, an increase in deficiency of complement factors and diversity of parasite strategies of immune evasion demonstrate the unsuccessful effort to control the infection. In the present paper, we will discuss basic aspects of complement activation, the structure of the lectin pathway components, genetic deficiency of complement factors, and new therapeutic opportunities to target the complement system to control infection.

The Murine Factor H-Related Protein FHR-B Promotes Complement Activation

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Marcell Cserhalmi

2017-09-01

Full Text Available Factor H-related (FHR proteins consist of varying number of complement control protein domains that display various degrees of sequence identity to respective domains of the alternative pathway complement inhibitor factor H (FH. While such FHR proteins are described in several species, only human FHRs were functionally investigated. Their biological role is still poorly understood and in part controversial. Recent studies on some of the human FHRs strongly suggest a role for FHRs in enhancing complement activation via competing with FH for binding to certain ligands and surfaces. The aim of the current study was the functional characterization of a murine FHR, FHR-B. To this end, FHR-B was expressed in recombinant form. Recombinant FHR-B bound to human C3b and was able to compete with human FH for C3b binding. FHR-B supported the assembly of functionally active C3bBb alternative pathway C3 convertase via its interaction with C3b. This activity was confirmed by demonstrating C3 activation in murine serum. In addition, FHR-B bound to murine pentraxin 3 (PTX3, and this interaction resulted in murine C3 fragment deposition due to enhanced complement activation in mouse serum. FHR-B also induced C3 deposition on C-reactive protein, the extracellular matrix (ECM extract Matrigel, and endothelial cell-derived ECM when exposed to mouse serum. Moreover, mouse C3 deposition was strongly enhanced on necrotic Jurkat T cells and the mouse B cell line A20 by FHR-B. FHR-B also induced lysis of sheep erythrocytes when incubated in mouse serum with FHR-B added in excess. Altogether, these data demonstrate that, similar to human FHR-1 and FHR-5, mouse FHR-B modulates complement activity by promoting complement activation via interaction with C3b and via competition with murine FH.

New perspectives on mannan-binding lectin-mediated complement activation

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Degn, Søren Egedal; Thiel, Steffen; Jensenius, Jens Christian

2007-01-01

The complement system is an important part of the innate immune system, mediating several major effector functions and modulating adaptive immune responses. Three complement activation pathways exist: the classical pathway (CP), the alternative pathway (AP), and the lectin pathway (LP). The LP......, allowing C3 activation in the absence of components otherwise believed critical. The classical bypass pathways are dependent on C1 and components of the AP. A recent study has shown the existence also of a lectin bypass pathway dependent on mannan-binding lectin (MBL) and AP components. The emerging...

Complement factor H protects mice from ischemic acute kidney injury but is not critical for controlling complement activation by glomerular IgM.

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Goetz, Lindsey; Laskowski, Jennifer; Renner, Brandon; Pickering, Matthew C; Kulik, Liudmila; Klawitter, Jelena; Stites, Erik; Christians, Uwe; van der Vlag, Johan; Ravichandran, Kameswaran; Holers, V Michael; Thurman, Joshua M

2018-05-01

Natural IgM binds to glomerular epitopes in several progressive kidney diseases. Previous work has shown that IgM also binds within the glomerulus after ischemia/reperfusion (I/R) but does not fully activate the complement system. Factor H is a circulating complement regulatory protein, and congenital or acquired deficiency of factor H is a strong risk factor for several types of kidney disease. We hypothesized that factor H controls complement activation by IgM in the kidney after I/R, and that heterozygous factor H deficiency would permit IgM-mediated complement activation and injury at this location. We found that mice with targeted heterozygous deletion of the gene for factor H developed more severe kidney injury after I/R than wild-type controls, as expected, but that complement activation within the glomeruli remained well controlled. Furthermore, mice that are unable to generate soluble IgM were not protected from renal I/R, even in the setting of heterozygous factor H deficiency. These results demonstrate that factor H is important for limiting injury in the kidney after I/R, but it is not critical for controlling complement activation by immunoglobulin within the glomerulus in this setting. IgM binds to glomerular epitopes after I/R, but it is not a significant source of injury. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sodium polyanethole sulfonate as an inhibitor of activation of complement function in blood culture systems

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Palarasah, Yaseelan; Skjoedt, Mikkel-Ole; Vitved, Lars

2010-01-01

complement activation pathways: the classical, alternative, and lectin pathways, respectively. Inhibition of complement activity by SPS is caused by a blocking of complement activation and is not a result of complement consumption. The classical pathway is inhibited at SPS concentrations greater than 0.1 mg...... findings also open up the possibility of a new assay for the assessment of the functional capacity of the lectin complement pathway....

Tuning complement activation and pathway through controlled molecular architecture of dextran chains in nanoparticle corona.

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Coty, Jean-Baptiste; Eleamen Oliveira, Elquio; Vauthier, Christine

2017-11-05

The understanding of complement activation by nanomaterials is a key to a rational design of safe and efficient nanomedicines. This work proposed a systematic study investigating how molecular design of nanoparticle coronas made of dextran impacts on mechanisms that trigger complement activation. The nanoparticles used for this work consisted of dextran-coated poly(isobutylcyanoacrylate) (PIBCA) nanoparticles have already been thoroughly characterized. Their different capacity to trigger complement activation established on the cleavage of the protein C3 was also already described making these nanoparticles good models to investigate the relation between the molecular feature of their corona and the mechanism by which they triggered complement activation. Results of this new study show that complement activation pathways can be selected by distinct architectures formed by dextran chains composing the nanoparticle corona. Assumptions that explain the relation between complement activation mechanisms triggered by the nanoparticles and the nanoparticle corona molecular feature were proposed. These results are of interest to better understand how the design of dextran-coated nanomaterials will impact interactions with the complement system. It can open perspectives with regard to the selection of a preferential complement activation pathway or prevent the nanoparticles to activate the complement system, based on a rational choice of the corona configuration. Copyright © 2017 Elsevier B.V. All rights reserved.

Assembly and activation of alternative complement components on endothelial cell-anchored ultra-large von Willebrand factor links complement and hemostasis-thrombosis.

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Nancy A Turner

Full Text Available Vascular endothelial cells (ECs express and release protein components of the complement pathways, as well as secreting and anchoring ultra-large von Willebrand factor (ULVWF multimers in long string-like structures that initiate platelet adhesion during hemostasis and thrombosis. The alternative complement pathway (AP is an important non-antibody-requiring host defense system. Thrombotic microangiopathies can be associated with defective regulation of the AP (atypical hemolytic-uremic syndrome or with inadequate cleavage by ADAMTS-13 of ULVWF multimeric strings secreted by/anchored to ECs (thrombotic thrombocytopenic purpura. Our goal was to determine if EC-anchored ULVWF strings caused the assembly and activation of AP components, thereby linking two essential defense mechanisms.We quantified gene expression of these complement components in cultured human umbilical vein endothelial cells (HUVECs by real-time PCR: C3 and C5; complement factor (CF B, CFD, CFP, CFH and CFI of the AP; and C4 of the classical and lectin (but not alternative complement pathways. We used fluorescent microscopy, monospecific antibodies against complement components, fluorescent secondary antibodies, and the analysis of >150 images to quantify the attachment of HUVEC-released complement proteins to ULVWF strings secreted by, and anchored to, the HUVECs (under conditions of ADAMTS-13 inhibition. We found that HUVEC-released C4 did not attach to ULVWF strings, ruling out activation of the classical and lectin pathways by the strings. In contrast, C3, FB, FD, FP and C5, FH and FI attached to ULVWF strings in quantitative patterns consistent with assembly of the AP components into active complexes. This was verified when non-functional FB blocked the formation of AP C3 convertase complexes (C3bBb on ULVWF strings.AP components are assembled and activated on EC-secreted/anchored ULVWF multimeric strings. Our findings provide one possible molecular mechanism for clinical

Colostral whey concentrate supplement increases complement activity in the sera of neonatal calves.

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Rokka, S; Korhonen, B H; Nousiainen, J; Marnila, P

2001-08-01

We evaluated the effect of a commercial bovine colostral whey on the complement-mediated immune responses of calves. Two groups of neonatal calves were fed, in addition to whole milk (WM) and pooled colostrum (PC), different amounts of a commercial immunoglobulin concentrate made from pooled colostral whey (Ig-C) for the first two feedings post natum. The control group was fed WM and PC only. Serum samples were obtained at the ages of 2, 7, 14 and 30 d. Bacteriolytic activity against complement-sensitive Escherichia coli JM103 and opsonic activity against complement-lysis-resistant E. coli IH3080 strains were studied, as well as the levels of C3 complement component and E. coli JM103 specific antibodies in the sera. Groups fed Ig-C had 2-3 times higher bacteriolytic activity than the control group of both the classic (P complement activities of serum can be increased substantially by feeding colostral whey concentrate to calves during their first days of life.

Complement factor H binds malondialdehyde epitopes and protects from oxidative stress

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Weismann, David; Hartvigsen, Karsten; Lauer, Nadine

2011-01-01

peroxidation product that accumulates in many pathophysiological processes, including AMD. Here we identify complement factor H (CFH) as a major MDA-binding protein that can block both the uptake of MDA-modified proteins by macrophages and MDA-induced proinflammatory effects in vivo in mice. The CFH...... polymorphism H402, which is strongly associated with AMD, markedly reduces the ability of CFH to bind MDA, indicating a causal link to disease aetiology. Our findings provide important mechanistic insights into innate immune responses to oxidative stress, which may be exploited in the prevention of and therapy...

Complement activation by ceramide transporter proteins.

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Bode, Gerard H; Losen, Mario; Buurman, Wim A; Veerhuis, Robert; Molenaar, Peter C; Steinbusch, Harry W M; De Baets, Marc H; Daha, Mohamed R; Martinez-Martinez, Pilar

2014-02-01

C1q is the initiator of the classical complement pathway and, as such, is essential for efficient opsonization and clearance of pathogens, altered self-structures, and apoptotic cells. The ceramide transporter protein (CERT) and its longer splicing isoform CERTL are known to interact with extracellular matrix components, such as type IV collagen, and with the innate immune protein serum amyloid P. In this article, we report a novel function of CERT in the innate immune response. Both CERT isoforms, when immobilized, were found to bind the globular head region of C1q and to initiate the classical complement pathway, leading to activation of C4 and C3, as well as generation of the membrane attack complex C5b-9. In addition, C1q was shown to bind to endogenous CERTL on the surface of apoptotic cells. These results demonstrate the role of CERTs in innate immunity, especially in the clearance of apoptotic cells.

Intracellular Complement Activation Sustains T Cell Homeostasis and Mediates Effector Differentiation

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Liszewski, M. Kathryn; Kolev, Martin; Le Friec, Gaelle; Leung, Marilyn; Bertram, Paula G.; Fara, Antonella F.; Subias, Marta; Pickering, Matthew C.; Drouet, Christian; Meri, Seppo; Arstila, T. Petteri; Pekkarinen, Pirkka T.; Ma, Margaret; Cope, Andrew; Reinheckel, Thomas; Rodriguez de Cordoba, Santiago; Afzali, Behdad; Atkinson, John P.; Kemper, Claudia

2013-01-01

Summary Complement is viewed as a critical serum-operative component of innate immunity, with processing of its key component, C3, into activation fragments C3a and C3b confined to the extracellular space. We report here that C3 activation also occurred intracellularly. We found that the T cell-expressed protease cathepsin L (CTSL) processed C3 into biologically active C3a and C3b. Resting T cells contained stores of endosomal and lysosomal C3 and CTSL and substantial amounts of CTSL-generated C3a. While “tonic” intracellular C3a generation was required for homeostatic T cell survival, shuttling of this intracellular C3-activation-system to the cell surface upon T cell stimulation induced autocrine proinflammatory cytokine production. Furthermore, T cells from patients with autoimmune arthritis demonstrated hyperactive intracellular complement activation and interferon-γ production and CTSL inhibition corrected this deregulated phenotype. Importantly, intracellular C3a was observed in all examined cell populations, suggesting that intracellular complement activation might be of broad physiological significance. PMID:24315997

Variants in Complement Factor H and Complement Factor H-Related Protein Genes, CFHR3 and CFHR1, Affect Complement Activation in IgA Nephropathy.

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Zhu, Li; Zhai, Ya-Ling; Wang, Feng-Mei; Hou, Ping; Lv, Ji-Cheng; Xu, Da-Min; Shi, Su-Fang; Liu, Li-Jun; Yu, Feng; Zhao, Ming-Hui; Novak, Jan; Gharavi, Ali G; Zhang, Hong

2015-05-01

Complement activation is common in patients with IgA nephropathy (IgAN) and associated with disease severity. Our recent genome-wide association study of IgAN identified susceptibility loci on 1q32 containing the complement regulatory protein-encoding genes CFH and CFHR1-5, with rs6677604 in CFH as the top single-nucleotide polymorphism and CFHR3-1 deletion (CFHR3-1∆) as the top signal for copy number variation. In this study, to explore the clinical effects of variation in CFH, CFHR3, and CFHR1 on IgAN susceptibility and progression, we enrolled two populations. Group 1 included 1178 subjects with IgAN and available genome-wide association study data. Group 2 included 365 subjects with IgAN and available clinical follow-up data. In group 1, rs6677604 was associated with mesangial C3 deposition by genotype-phenotype correlation analysis. In group 2, we detected a linkage between the rs6677604-A allele and CFHR3-1∆ and found that the rs6677604-A allele was associated with higher serum levels of CFH and lower levels of the complement activation split product C3a. Furthermore, CFH levels were positively associated with circulating C3 levels and negatively associated with mesangial C3 deposition. Moreover, serum levels of the pathogenic galactose-deficient glycoform of IgA1 were also associated with the degree of mesangial C3 deposition in patients with IgAN. Our findings suggest that genetic variants in CFH, CFHR3, and CFHR1 affect complement activation and thereby, predispose patients to develop IgAN. Copyright © 2015 by the American Society of Nephrology.

Complementing xeroderma pigmentosum fibroblasts restore biological activity to UV-damaged DNA

International Nuclear Information System (INIS)

Day, R.S. III; Kraemer, K.H.; Robbins, J.H.

1975-01-01

UV survival curves of adenovirus 2 using fused complementing xeroderma pigmentosum fibroblast strains as virus hosts showed a component with an inactivation slope identical to that given by normal cells. This component was not observed when the fibroblasts were not fused or when fusions involved strains in the same complementing group. Extrapolation to zero dose indicated that three percent of the viral plaque-forming units had infected cells capable of normal repair; this suggested that three percent of the cells were complementing heterokaryons. Thus, heterokaryons formed from xeroderma pigmentosum fibroblasts belonging to different complementation groups are as capable of restoring biological activity to UV-damaged adenovirus 2 as are normal cells

Pseudomonas aeruginosa alkaline protease blocks complement activation via the classical and lectin pathways.

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Laarman, Alexander J; Bardoel, Bart W; Ruyken, Maartje; Fernie, Job; Milder, Fin J; van Strijp, Jos A G; Rooijakkers, Suzan H M

2012-01-01

The complement system rapidly detects and kills Gram-negative bacteria and supports bacterial killing by phagocytes. However, bacterial pathogens exploit several strategies to evade detection by the complement system. The alkaline protease (AprA) of Pseudomonas aeruginosa has been associated with bacterial virulence and is known to interfere with complement-mediated lysis of erythrocytes, but its exact role in bacterial complement escape is unknown. In this study, we analyzed how AprA interferes with complement activation and whether it could block complement-dependent neutrophil functions. We found that AprA potently blocked phagocytosis and killing of Pseudomonas by human neutrophils. Furthermore, AprA inhibited opsonization of bacteria with C3b and the formation of the chemotactic agent C5a. AprA specifically blocked C3b deposition via the classical and lectin pathways, whereas the alternative pathway was not affected. Serum degradation assays revealed that AprA degrades both human C1s and C2. However, repletion assays demonstrated that the mechanism of action for complement inhibition is cleavage of C2. In summary, we showed that P. aeruginosa AprA interferes with classical and lectin pathway-mediated complement activation via cleavage of C2.

The Structure-Activity Relationship between Marine Algae Polysaccharides and Anti-Complement Activity

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Jin, Weihua; Zhang, Wenjing; Liang, Hongze; Zhang, Quanbin

2015-01-01

In this study, 33 different polysaccharides were prepared to investigate the structure-activity relationships between the polysaccharides, mainly from marine algae, and anti-complement activity in the classical pathway. Factors considered included extraction methods, fractionations, molecular weight, molar ratio of galactose to fucose, sulfate, uronic acid (UA) content, linkage, branching, and the type of monosaccharide. It was shown that the larger the molecular weights, the better the activities. The molar ratio of galactose (Gal) to fucose (Fuc) was a positive factor at a concentration lower than 10 µg/mL, while it had no effect at a concentration more than 10 µg/mL. In addition, sulfate was necessary; however, the sulfate content, the sulfate pattern, linkage and branching had no effect at a concentration of more than 10 µg/mL. Moreover, the type of monosaccharide had no effect. Laminaran and UA fractions had no activity; however, they could reduce the activity by decreasing the effective concentration of the active composition when they were mixed with the active compositions. The effect of the extraction methods could not be determined. Finally, it was observed that sulfated galactofucan showed good anti-complement activity after separation. PMID:26712768

Soluble and immobilized graphene oxide activates complement system differently dependent on surface oxidation state

DEFF Research Database (Denmark)

Wibroe, Peter Popp; Petersen, Søren Vermehren; Bovet, Nicolas Emile

2016-01-01

on two related elements of innate immunity: the complement system and interleukin-6 (IL-6) release in human blood. In solution, there was a decrease in GO-mediated complement activation with decreasing surface oxygen content (and altered oxygen functionality), whereas with immobilized GO complement...... response were reversed and increased with decreasing oxygen content. GO solutions, at concentrations below complement activating threshold, did not induce IL-6 release from human blood leukocytes, and further dampened lipopolysaccharide-induced IL-6 release in the whole blood. The latter effect became more...... profound with GO's having higher oxygen content. This protective role of GO solutions, however, disappeared at higher concentrations above complement-activating threshold. We discuss these results in relation to GO surface structure and properties, and implications for local administration and development...

Functional analysis of Ficolin-3 mediated complement activation

DEFF Research Database (Denmark)

Hein, Estrid; Honoré, Christian Le Fèvre; Skjoedt, Mikkel-Ole

2010-01-01

assessed by C4, C3 and terminal complement complex (TCC) deposition. Serum Ficolin-3 bound to acBSA in a calcium dependent manner, while only minimal binding of Ficolin-2 and no binding of Ficolin-1 were observed. No binding to normal BSA was seen for any of the Ficolins. Serum C4, C3 and TCC deposition...... was applied to the samples that inhibited interference from the classical pathway due to the presence of anti-BSA antibodies in some sera. We describe a novel functional method for measuring complement activation mediated by Ficolin-3 in human serum up to the formation of TCC. The assay provides...

Complement activation in Ghanaian children with severe Plasmodium falciparum malaria

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Ofori Michael F

2007-12-01

Full Text Available Abstract Background Severe anaemia (SA, intravascular haemolysis (IVH and respiratory distress (RD are severe forms of Plasmodium falciparum malaria, with RD reported to be of prognostic importance in African children with malarial anaemia. Complement factors have been implicated in the mechanism leading to excess anaemia in acute P. falciparum infection. Methods The direct Coombs test (DCT and flow cytometry were used to investigate the mean levels of RBC-bound complement fragments (C3d and C3bαβ and the regulatory proteins [complement receptor 1 (CD35 and decay accelerating factor (CD55] in children with discrete clinical forms of P. falciparum malaria. The relationship between the findings and clinical parameters including coma, haemoglobin (Hb levels and RD were investigated. Results Of the 484 samples tested, 131(27% were positive in DCT, out of which 115/131 (87.8% were positive for C3d alone while 16/131 (12.2% were positive for either IgG alone or both. 67.4% of the study population were below 5 years of age and DCT positivity was more common in this age group relative to children who were 5 years or older (Odds ratio, OR = 3.8; 95%CI, 2.2–6.7, p Conclusion These results suggest that complement activation contributed to anaemia in acute childhood P. falciparum malaria, possibly through induction of erythrophagocytosis and haemolysis. In contrast to other studies, this study did not find association between levels of the complement regulatory proteins, CD35 and CD55 and malarial anaemia. These findings suggest that complement activation could also be involved in the pathogenesis of RD but larger studies are needed to confirm this finding.

Depressed activation of the lectin pathway of complement in hereditary angioedema

DEFF Research Database (Denmark)

Varga, L; Széplaki, G; Laki, J

2008-01-01

) in three complement activation pathways. Functional activity of the CP, LP and AP were measured in the sera of 68 adult patients with hereditary angioedema (HAE) and 64 healthy controls. In addition, the level of C1q, MBL, MBL-associated serine protease-2 (MASP-2), C4-, C3- and C1INH was measured...... by standard laboratory methods. MBL-2 genotypes were determined by polymerase chain reaction. Besides the complement alterations (low CP and C1INH activity, low C4-, C1INH concentrations), which characterize HAE, the level of MASP-2 was also lower (P = 0.0001) in patients compared with controls. Depressed LP...

Anopheles Midgut Epithelium Evades Human Complement Activity by Capturing Factor H from the Blood Meal

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Khattab, Ayman; Barroso, Marta; Miettinen, Tiera; Meri, Seppo

2015-01-01

Hematophagous vectors strictly require ingesting blood from their hosts to complete their life cycles. Exposure of the alimentary canal of these vectors to the host immune effectors necessitates efficient counteractive measures by hematophagous vectors. The Anopheles mosquito transmitting the malaria parasite is an example of hematophagous vectors that within seconds can ingest human blood double its weight. The innate immune defense mechanisms, like the complement system, in the human blood should thereby immediately react against foreign cells in the mosquito midgut. A prerequisite for complement activation is that the target cells lack complement regulators on their surfaces. In this work, we analyzed whether human complement is active in the mosquito midgut, and how the mosquito midgut cells protect themselves against complement attack. We found that complement remained active for a considerable time and was able to kill microbes within the mosquito midgut. However, the Anopheles mosquito midgut cells were not injured. These cells were found to protect themselves by capturing factor H, the main soluble inhibitor of the alternative complement pathway. Factor H inhibited complement on the midgut cells by promoting inactivation of C3b to iC3b and preventing the activity of the alternative pathway amplification C3 convertase enzyme. An interference of the FH regulatory activity by monoclonal antibodies, carried to the midgut via blood, resulted in increased mosquito mortality and reduced fecundity. By using a ligand blotting assay, a putative mosquito midgut FH receptor could be detected. Thereby, we have identified a novel mechanism whereby mosquitoes can tolerate human blood. PMID:25679788

Anopheles midgut epithelium evades human complement activity by capturing factor H from the blood meal.

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Ayman Khattab

2015-02-01

Full Text Available Hematophagous vectors strictly require ingesting blood from their hosts to complete their life cycles. Exposure of the alimentary canal of these vectors to the host immune effectors necessitates efficient counteractive measures by hematophagous vectors. The Anopheles mosquito transmitting the malaria parasite is an example of hematophagous vectors that within seconds can ingest human blood double its weight. The innate immune defense mechanisms, like the complement system, in the human blood should thereby immediately react against foreign cells in the mosquito midgut. A prerequisite for complement activation is that the target cells lack complement regulators on their surfaces. In this work, we analyzed whether human complement is active in the mosquito midgut, and how the mosquito midgut cells protect themselves against complement attack. We found that complement remained active for a considerable time and was able to kill microbes within the mosquito midgut. However, the Anopheles mosquito midgut cells were not injured. These cells were found to protect themselves by capturing factor H, the main soluble inhibitor of the alternative complement pathway. Factor H inhibited complement on the midgut cells by promoting inactivation of C3b to iC3b and preventing the activity of the alternative pathway amplification C3 convertase enzyme. An interference of the FH regulatory activity by monoclonal antibodies, carried to the midgut via blood, resulted in increased mosquito mortality and reduced fecundity. By using a ligand blotting assay, a putative mosquito midgut FH receptor could be detected. Thereby, we have identified a novel mechanism whereby mosquitoes can tolerate human blood.

Bioactive lysophospholipids generated by hepatic lipase degradation of lipoproteins lead to complement activation via the classical pathway.

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Ma, Wanchao; Paik, David C; Barile, Gaetano R

2014-09-09

We determined bioactivity of lysophospholipids generated by degradation of the low-density (LDL), very low-density (VLDL), and high-density (HDL) lipoproteins with hepatic lipase (HL), cholesterol esterase (CE), and lipoprotein-associated phospholipase A2 (Lp-PLA2). The LDL, VLDL, and HDL were treated with HL, CE, and Lp-PLA2 after immobilization on plates, and complement activation studies were performed with diluted human serum. Complement component 3 (C3) fixation, a marker for complement activation, was determined with a monoclonal anti-human C3d antibody. Enzymatic properties of HL and CE were assayed with triglyceride and phosphatidylcholine substrates for triglyceride hydrolase and phospholipase A activities. The ARPE-19 cells were used for viability studies. The HL degradation of human lipoproteins LDL, VLDL, or HDL results in the formation of modified lipoproteins that can activate the complement pathway. Complement activation is dose- and time-dependent upon HL and occurs via the classical pathway. Enzymatic studies suggest that the phospholipase A1 activity of HL generates complement-activating lysophospholipids. C-reactive protein (CRP), known to simultaneously interact with complement C1 and complement factor H (CFH), further enhances HL-induced complement activation. The lysophospholipids, 1-Palmitoyl-sn-glycero-3-phosphocholine and 1-Oleoyl-sn-glycero-3-phosphocholine, can be directly cytotoxic to ARPE-19 cells. The HL degradation of lipoproteins, known to accumulate in the outer retina and in drusen, can lead to the formation of bioactive lysophospholipids that can trigger complement activation and induce RPE cellular dysfunction. Given the known risk associations for age-related macular degeneration (AMD) with HL, CRP, and CFH, this study elucidates a possible damage pathway for age-related macular degeneration (AMD) in genetically predisposed individuals, that HL activity may lead to accumulation of lysophospholipids to initiate complement

The paralogous salivary anti-complement proteins IRAC I and IRAC II encoded by Ixodes ricinus ticks have broad and complementary inhibitory activities against the complement of different host species.

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Schroeder, Hélène; Daix, Virginie; Gillet, Laurent; Renauld, Jean-Christophe; Vanderplasschen, Alain

2007-02-01

Several observations suggest that inhibition of the host complement alternative pathway by Ixodes tick saliva is crucial to achieve blood feeding. We recently described two paralogous anti-complement proteins called Ixodes ricinus anti-complement (IRAC) proteins I and II co-expressed in I. ricinus salivary glands. Phylogenetic analyses suggested that these sequences were diversifying by a process of positive Darwinian selection, possibly leading to molecules with different biological properties. In the present study, we tested the hypothesis that each paralogue may have different inhibitory activities against the complement of different natural host species, thereby contributing to broaden the host range of I. ricinus ticks. IRAC I and IRAC II were tested against the complement of eight I. ricinus natural host species (six mammals and two birds). The results demonstrate that IRAC I and IRAC II have broad and complementary inhibition activities against the complement of different host species. This report is the first description of paralogous anti-complement molecules encoded by a pathogen with broad and complementary inhibitory activities against the complement of different host species.

A novel method for direct measurement of complement convertases activity in human serum.

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Blom, A M; Volokhina, E B; Fransson, V; Strömberg, P; Berghard, L; Viktorelius, M; Mollnes, T E; López-Trascasa, M; van den Heuvel, L P; Goodship, T H; Marchbank, K J; Okroj, M

2014-10-01

Complement convertases are enzymatic complexes that play a central role in sustaining and amplification of the complement cascade. Impairment of complement function leads directly or indirectly to pathological conditions, including higher infection rate, kidney diseases, autoimmune- or neurodegenerative diseases and ischaemia-reperfusion injury. An assay for direct measurement of activity of the convertases in patient sera is not available. Existing assays testing convertase function are based on purified complement components and, thus, convertase formation occurs under non-physiological conditions. We designed a new assay, in which C5 blocking compounds enabled separation of the complement cascade into two phases: the first ending at the stage of C5 convertases and the second ending with membrane attack complex formation. The use of rabbit erythrocytes or antibody-sensitized sheep erythrocytes as the platforms for convertase formation enabled easy readout based on measurement of haemolysis. Thus, properties of patient sera could be studied directly regarding convertase activity and membrane attack complex formation. Another advantage of this assay was the possibility to screen for host factors such as C3 nephritic factor and other anti-complement autoantibodies, or gain-of-function mutations, which prolong the half-life of complement convertases. Herein, we present proof of concept, detailed description and validation of this novel assay. © 2014 British Society for Immunology.

An Anti-C1s Monoclonal, TNT003, Inhibits Complement Activation Induced by Antibodies Against HLA.

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Thomas, K A; Valenzuela, N M; Gjertson, D; Mulder, A; Fishbein, M C; Parry, G C; Panicker, S; Reed, E F

2015-08-01

Antibody-mediated rejection (AMR) of solid organ transplants (SOT) is characterized by damage triggered by donor-specific antibodies (DSA) binding donor Class I and II HLA (HLA-I and HLA-II) expressed on endothelial cells. While F(ab')2 portions of DSA cause cellular activation and proliferation, Fc regions activate the classical complement cascade, resulting in complement deposition and leukocyte recruitment, both hallmark features of AMR. We characterized the ability of an anti-C1s monoclonal antibody, TNT003, to inhibit HLA antibody (HLA-Ab)-induced complement activation. Complement deposition induced by HLA-Ab was evaluated using novel cell- and bead-based assays. Human aortic endothelial cells (HAEC) were cultured with HLA-Ab and human complement; production of activated complement proteins was measured by flow cytometry. Additionally, C3d deposition was measured on single antigen beads (SAB) mixed with HLA-Ab and human complement. TNT003 inhibited HLA-Ab mediated complement deposition on HAEC in a concentration-dependent manner; C3a, C4a and C5a anaphylatoxin production was also diminished by TNT003. Finally, TNT003 blocked C3d deposition induced by Class I (HLAI-Ab)- and Class II (HLAII-Ab)-specific antibodies on SAB. These data suggest TNT003 may be useful for modulating the effects of DSA, as TNT003 inhibits complement deposition and split product formation generated by HLA-I/II-Ab in vitro. © 2015 The Authors. American Journal of Transplantation Published by Wiley Periodicals, Inc.

Mesenchymal stromal cells engage complement and complement receptor bearing innate effector cells to modulate immune responses.

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Guido Moll

Full Text Available Infusion of human third-party mesenchymal stromal cells (MSCs appears to be a promising therapy for acute graft-versus-host disease (aGvHD. To date, little is known about how MSCs interact with the body's innate immune system after clinical infusion. This study shows, that exposure of MSCs to blood type ABO-matched human blood activates the complement system, which triggers complement-mediated lymphoid and myeloid effector cell activation in blood. We found deposition of complement component C3-derived fragments iC3b and C3dg on MSCs and fluid-phase generation of the chemotactic anaphylatoxins C3a and C5a. MSCs bound low amounts of immunoglobulins and lacked expression of complement regulatory proteins MCP (CD46 and DAF (CD55, but were protected from complement lysis via expression of protectin (CD59. Cell-surface-opsonization and anaphylatoxin-formation triggered complement receptor 3 (CD11b/CD18-mediated effector cell activation in blood. The complement-activating properties of individual MSCs were furthermore correlated with their potency to inhibit PBMC-proliferation in vitro, and both effector cell activation and the immunosuppressive effect could be blocked either by using complement inhibitor Compstatin or by depletion of CD14/CD11b-high myeloid effector cells from mixed lymphocyte reactions. Our study demonstrates for the first time a major role of the complement system in governing the immunomodulatory activity of MSCs and elucidates how complement activation mediates the interaction with other immune cells.

Complement activation and liver impairment in trichloroethylene-sensitized BALB/c mice.

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Zhang, Jiaxiang; Zha, Wansheng; Wang, Feng; Jiang, Tao; Xu, Shuhai; Yu, Junfeng; Zhou, Chengfan; Shen, Tong; Wu, Changhao; Zhu, Qixing

2013-01-01

Our recent studies have shown that trichloroethylene (TCE) was able to induce multisystem injuries in the form of occupational medicamentosa-like dermatitis, including skin, kidney, and liver damages. However, the role of complement activation in the immune-mediated liver injury is not known. This study examined the role of complement activation in the liver injury in a mouse model of TCE-induced sensitization. Treatment of female BALB/c mice with TCE under specific dosing protocols resulted in skin inflammation and sensitization. Skin edema and erythema occurred in TCE-sensitized groups. Trichloroethylene sensitization produced liver histopathological lesions, increased serum alanine aminotransferase, aspartate transaminase activities, and the relative liver weight. The concentrations of serum complement components C3a-desArg, C5a-desArg, and C5b-9 were significantly increased in 24-hour, 48-hour, and 72-hour sensitization-positive groups treated with TCE and peaked in the 72-hour sensitization-positive group. Depositions of C3a, C5a, and C5b-9 into the liver tissue were also revealed by immunohistochemistry. Immunofluorescence further verified high C5b-9 expression in 24-hour, 48-hour, and 72-hour sensitization-positive groups in response to TCE treatment. Reverse transcription-polymerase chain reaction detected C3 messenger RNA expression in the liver, and this was significantly increased in 24-hour and 48-hour sensitization-positive groups with a transient reduction at 72 hours. These results provide the first experimental evidence that complement activation may play a key role in the generation and progression of immune-mediated hepatic injury by exposure to TCE.

Core shell methyl methacrylate chitosan nanoparticles: In vitro mucoadhesion and complement activation

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F Atyabi

2011-10-01

Full Text Available Background and the purpose of the study: Studies show that chitosan nanoparticles increase mucoadhesivity and penetration of large molecules across mucosal surface. The aim of the present study was to investigate the use of thiolated chitosan in the development of polysaccharide-coated nanoparticles in order to confer specific functionality to the system. Methods: Methyl methacrylate nanoparticles were coated with thiolated chitosan using a radical polymerization method. Thiolation was carried out using glutathione (GSH to improve mucoadhesivity and permeation enhancing properties of chitosan. Mucoadhesion studies were carried out by calculating the amount of mucin adsorbed on nanoparticles in a specific period of time. Complement consumption was assessed in human serum (HS by measurement of the hemolytic capacity of the complement system after contact with nanoparticles.   Results:   The FT-IR and 1HNMR spectra both confirmed the synthesis and showed the conjugation of thiolated chitosan to methyl methacrylate (MMA homopolymer. Nanoparticles were spherical having a mean diameter within the range of about 334-650 nm and their positive zeta potential values indicated the presence of the cationic polysaccharide at the nanoparticle surface. Increasing the amount of thiolated chitosan led to mucoadhesivity and complement activation. However there was not dose dependent correlation between these phenomenons and the absence of thiolated chitosan led to particles with larger size, and without ability to activate complement process. Major conclusion: It can be concluded that nanoparticles could be used for the mucosal delivery of peptides and proteins. Results show that the thiolated chitosan had higher mucoadhesion and complement activation than unmodified chitosan.

Increased activity of the mannan-binding lectin complement activation pathway in patients with colorectal cancer

DEFF Research Database (Denmark)

Ytting, H; Jensenius, Jens Christian; Christensen, I J

2004-01-01

BACKGROUND: Postoperative bacterial infectious complications are frequent in patients with colorectal cancer (CRC), with subsequent increased recurrence rates and poor prognosis. Deficiency of the mannan-binding lectin (MBL) complement activation pathway may cause increased risk of infection......: Serum MBL concentrations and MBL/MASP activity were determined using immunofluorometric assays. The levels are presented as the median, inter-quartile range and range. RESULTS: Serum MBL levels were significantly (P cancer (1384 (400-2188) ng/mL) (median...... in the colon or rectum, and disease stages according to Dukes' classification. No statistical difference (P=0.20) in frequency of MBL deficiency was found between the patients (20%) and the donors (27%). CONCLUSIONS: Overall, the MBL complement activation pathway is significantly increased in patients...

Polysaccharides from Sargassum thunbergii: Monthly variations and anti-complement and anti-tumour activities.

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Jin, Weihua; Liu, Ge; Zhong, Weihong; Sun, Chaomin; Zhang, Quanbin

2017-12-01

Monthly variations of polysaccharides from Sargassum thunbergii and their anti-complement and anti-tumour activities were investigated. It was observed that an increase in fucose and total sugar contents occurred during the growth period (from early April to mid-June), accompanied by a decrease in molar ratios of other monosaccharides to fucose. The highest yields were obtained from early July to early September, which was in accordance with the significant increase in molar ratio of glucose to fucose and decrease in molar ratio of other monosaccharides to fucose. And the above results suggested that S. Thunbergii synthesized large amount of laminaran, the storage substance of brown algae, during the senescence period. However, sulfate contents were relatively stable in the life cycle of S. thunbergii. These results suggested that S. thunbergii synthesized complex sulfated heteropolysacchairdes during inactive period, while during other periods, it synthesized more sulfated galactofucan. All polysaccharides showed anti-complement activity, suggesting that the harvesting time did not influence the anti-complement activities. In the anti-tumour assay in vitro, the polysaccharides taken during the senescence period had much lower anti-tumour activity, suggesting that fucoidan, but not laminaran, determined the anti-tumour activities. Therefore, polysaccharides from S. thunbergii might have great potential in anti-complement and anti-tumour application. Copyright © 2017 Elsevier B.V. All rights reserved.

Potassium humate inhibits complement activation and the production of inflammatory cytokines in vitro

Energy Technology Data Exchange (ETDEWEB)

van Rensburg, C.E.J.; Naude, P.J. [University of Pretoria, Pretoria (South Africa)

2009-08-15

The effects of brown coal derived potassium humate on lymphocyte proliferation, cytokine production and complement activation were investigated in vitro. Potassium humate increased lymphocyte proliferation of phytohaemaglutinin A (PHA) and pokeweed mitogen (PWM) stimulated mononuclear lymphocytes (MNL) in vitro from concentrations of 20 to 80 {mu} g/ml, in a dose dependant manner. On the other hand potassium humate, at 40 {mu} g/ml, significantly inhibited the release of TNF-alpha, IL-1 beta, IL-6 and IL-10 by PHA stimulated MNL. Regarding complement activation it was found that potassium humate inhibits the activation of both the alternative and classical pathways without affecting the stability of the red blood cell membranes. These results indicate that the anti-inflammatory potential of potassium humate could be partially due to the inhibition of pro-inflammatory cytokines responsible for the initiation of these reactions as well as inhibition of complement activation. The increased lymphocyte proliferation observed, might be due to increased IL-2 production as previously been documented.

An assay for the mannan-binding lectin pathway of complement activation

DEFF Research Database (Denmark)

Petersen, Steen Vang; Thiel, S; Jensen, L

2001-01-01

activation. Therefore, in a generally applicable complement activation assay specific for the MBL pathway, the activity of the classical pathway must be inhibited. This can be accomplished by exploiting the finding that high ionic strength buffers inhibit the binding of C1q to immune complexes and disrupt...

Activation of the lectin complement pathway on human renal ...

African Journals Online (AJOL)

This study aimed to investigate the roles of high glucose and mannose-binding lectin (MBL) on the activation of the lectin complement pathway (LCP) on human renal glomerular endothelial cells (HRGECs) in vitro. Flow cytometry analysis, immunofluorescence staining and Western blot were used to detect the cell surface ...

Cyclodextrin Reduces Cholesterol Crystal-Induced Inflammation by Modulating Complement Activation

DEFF Research Database (Denmark)

Bakke, Siril S; Aune, Marie H; Niyonzima, Nathalie

2017-01-01

Cholesterol crystals (CC) are abundant in atherosclerotic plaques and promote inflammatory responses via the complement system and inflammasome activation. Cyclic oligosaccharide 2-hydroxypropyl-β-cyclodextrin (BCD) is a compound that solubilizes lipophilic substances. Recently we have shown...

Acute and prolonged complement activation in the central nervous system during herpes simplex encephalitis.

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Eriksson, Charlotta E; Studahl, Marie; Bergström, Tomas

2016-06-15

Herpes simplex encephalitis (HSE) is characterized by a pronounced inflammatory activity in the central nervous system (CNS). Here, we investigated the acute and prolonged complement system activity in HSE patients, by using enzyme-linked immunosorbent assays (ELISAs) for numerous complement components (C). We found increased cerebrospinal fluid concentrations of C3a, C3b, C5 and C5a in HSE patients compared with healthy controls. C3a and C5a concentrations remained increased also compared with patient controls. Our results conclude that the complement system is activated in CNS during HSE in the acute phase, and interestingly also in later stages supporting previous reports of prolonged inflammation. Copyright © 2016 Elsevier B.V. All rights reserved.

Structural insight into the recognition of complement C3 activation products by integrin receptors

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Bajic, Goran

2015-01-01

fragment C3a called anaphylatoxin. Complement leads to opsonization as the proteolytic fragment C3b becomes covalently linked to the activator surface through a reactive thioester. Self-surfaces are protected by complement regulators, whereas complement activation vividly amplifies on pathogens...... and their clearance by dendritic cells is mediated by αMβ2. The central molecule in my project, αMβ2 integrin, recognizes many diverse ligands including iC3b, but the molecular basis for such recognition was lacking. During my PhD I have obtained a major breakthrough in the dissection of iC3b interaction with αMβ2. I...

Spontaneous complement activation on human B cells results in localized membrane depolarization and the clustering of complement receptor type 2 and C3 fragments

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Løbner, Morten; Leslie, Robert G Q; Prodinger, Wolfgang M

2009-01-01

While our previous studies have demonstrated that complement activation induced by complement receptors type 2 (CR2/CD21) and 1 (CR1/CD35) results in C3-fragment deposition and membrane attack complex (MAC) formation in human B cells, the consequences of these events for B-cell functions remain u...

Fcγ and Complement Receptors and Complement Proteins in Neutrophil Activation in Rheumatoid Arthritis: Contribution to Pathogenesis and Progression and Modulation by Natural Products

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Adriana Balbina Paoliello-Paschoalato

2015-01-01

Full Text Available Rheumatoid arthritis (RA is a highly disabling disease that affects all structures of the joint and significantly impacts on morbidity and mortality in RA patients. RA is characterized by persistent inflammation of the synovial membrane lining the joint associated with infiltration of immune cells. Eighty to 90% of the leukocytes infiltrating the synovia are neutrophils. The specific role that neutrophils play in the onset of RA is not clear, but recent studies have evidenced that they have an important participation in joint damage and disease progression through the release of proteolytic enzymes, reactive oxygen species (ROS, cytokines, and neutrophil extracellular traps, in particular during frustrated phagocytosis of immune complexes (ICs. In addition, the local and systemic activation of the complement system contributes to the pathogenesis of RA and other IC-mediated diseases. This review discusses (i the participation of Fcγ and complement receptors in mediating the effector functions of neutrophils in RA; (ii the contribution of the complement system and ROS-dependent and ROS-independent mechanisms to joint damage in RA; and (iii the use of plant extracts, dietary compounds, and isolated natural compounds in the treatment of RA, focusing on modulation of the effector functions of neutrophils and the complement system activity and/or activation.

Increased complement C1q level marks active disease in human tuberculosis.

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Yi Cai

Full Text Available BACKGROUND: Complement functions as an important host defense system and complement C5 and C7 have been implicated in immunopathology of tuberculosis. However, little is known about the role of other complement components in tuberculosis. METHODS: Complement gene expression in peripheral blood mononuclear cells of tuberculosis patients and controls were determined using whole genome transcriptional microarray assays. The mRNA and protein levels of three C1q components, C1qA, C1qB, and C1qC, were further validated by qRT-PCR and enzyme-linked immunosorbent assay, respectively. The percentages of C1q expression in CD14 positive cells were determined by flow cytometry. Finally, C1qC protein level was quantified in the pleural fluid of tuberculosis and non-tuberculosis pleurisy. RESULTS: C1q expression increases significantly in the peripheral blood of patients with active tuberculosis compared to healthy controls and individuals with latent TB infection. The percentage of C1q-expressing CD14 positive cells is significantly increased in active TB patients. C1q expression in the peripheral blood correlates with sputum smear positivity in tuberculosis patients and is reduced after anti-tuberculosis chemotherapy. Notably, receiver operating characteristic analysis showed that C1qC mRNA levels in peripheral blood efficiently discriminate active from latent tuberculosis infection and healthy controls. Additionally, C1qC protein level in pleural effusion shows improved power in discriminating tuberculosis from non-tuberculosis pleurisy when compared to other inflammatory markers, such as IL-6 and TNF-α. CONCLUSIONS: C1q expression correlates with active disease in human tuberculosis. C1q could be a potential diagnostic marker to discriminate active tuberculosis from latent tuberculosis infection as well as tuberculosis pleurisy from non-tuberculosis pleurisy.

Complement activation in leprosy: a retrospective study shows elevated circulating terminal complement complex in reactional leprosy.

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Bahia El Idrissi, N; Hakobyan, S; Ramaglia, V; Geluk, A; Morgan, B Paul; Das, P Kumar; Baas, F

2016-06-01

Mycobacterium leprae infection gives rise to the immunologically and histopathologically classified spectrum of leprosy. At present, several tools for the stratification of patients are based on acquired immunity markers. However, the role of innate immunity, particularly the complement system, is largely unexplored. The present retrospective study was undertaken to explore whether the systemic levels of complement activation components and regulators can stratify leprosy patients, particularly in reference to the reactional state of the disease. Serum samples from two cohorts were analysed. The cohort from Bangladesh included multi-bacillary (MB) patients with (n = 12) or without (n = 46) reaction (R) at intake and endemic controls (n = 20). The cohort from Ethiopia included pauci-bacillary (PB) (n = 7) and MB (n = 23) patients without reaction and MB (n = 15) patients with reaction. The results showed that the activation products terminal complement complex (TCC) (P ≤ 0·01), C4d (P ≤ 0·05) and iC3b (P ≤ 0·05) were specifically elevated in Bangladeshi patients with reaction at intake compared to endemic controls. In addition, levels of the regulator clusterin (P ≤ 0·001 without R; P < 0·05 with R) were also elevated in MB patients, irrespective of a reaction. Similar analysis of the Ethiopian cohort confirmed that, irrespective of a reaction, serum TCC levels were increased significantly in patients with reactions compared to patients without reactions (P ≤ 0·05). Our findings suggests that serum TCC levels may prove to be a valuable tool in diagnosing patients at risk of developing reactions. © 2016 British Society for Immunology.

Soluble IgM links apoptosis to complement activation in early alcoholic liver disease in mice.

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Smathers, Rebecca L; Chiang, Dian J; McMullen, Megan R; Feldstein, Ariel E; Roychowdhury, Sanjoy; Nagy, Laura E

2016-04-01

Ethanol feeding in mice activates complement via C1q binding to apoptotic cells in the liver; complement contributes to ethanol-induced inflammation and injury. Despite the critical role of C1q in ethanol-induced injury, the mechanism by which ethanol activates C1q remains poorly understood. Secretory IgM (sIgM), traditionally considered to act as an anti-microbial, also has critical housekeeping functions, facilitating clearance of apoptotic cells, at least in part through activation of C1q. Therefore, we hypothesized that (1) ethanol-induced apoptosis in the liver recruits sIgM, facilitating the activation of C1q and complement and (2) C1INH (C1 esterase inhibitor), which inhibits C1 functional activity, prevents complement activation and decreases ethanol-induced liver injury. Female C57BL/6 wild-type, C1qa(-/-), BID(-/-) and sIgM(-/-) mice were fed ethanol containing liquid diets or pair-fed control diets. C1INH or vehicle was given via tail vein injection to ethanol- or pair-fed wild-type mice at 24 and 48h prior to euthanasia. Ethanol exposure increased apoptosis in the liver, as well as the accumulation of IgM in the liver. In the early stages of ethanol feeding, C1q co-localized with IgM in the peri-sinusoidal space of the liver and accumulation of IgM and C3b was dependent on ethanol-induced BID-dependent apoptosis. sIgM(-/-) mice were protected from both ethanol-induced activation of complement and early ethanol-induced liver injury when compared to wild-type mice. Treatment with C1INH also decreased hepatic C3b deposition and ethanol-induced injury. These data indicate that sIgM contributes to activation of complement and ethanol-induced increases in inflammatory cytokine expression and hepatocyte injury in the early stages of ethanol-induced liver injury. Copyright © 2016 Elsevier Ltd. All rights reserved.

Maternal and fetal alternative complement pathway activation in early severe preeclampsia.

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Hoffman, M Camille; Rumer, Kristen K; Kramer, Anita; Lynch, Anne M; Winn, Virginia D

2014-01-01

We sought to determine whether alternative complement activation fragment Bb (Bb) levels are elevated in the maternal, fetal, and placental blood in cases of severe preeclampsia (PE) compared with normotensive controls. This was a cross-sectional study of women admitted at ≥24 weeks gestation with or without severe PE. Maternal plasma was collected at the time of enrollment. Umbilical venous cord and intervillous space blood were collected at delivery. Plasma Bb levels were assessed using ELISA. Bb levels were compared between cases and controls. Median Bb levels were higher in the maternal plasma of severe PE subjects (n = 24) than in controls (n = 20), 1.45 ± 1.03 versus 0.65 ± 0.23 μg/mL, P < 0.001. In umbilical venous plasma, Bb levels were higher in severe PE subjects (n = 15) compared with controls (n = 15), 2.48 ± 1.40 versus 1.01 ± 0.57 μg/mL, P = 0.01. Activation fragment Bb is increased in the maternal and umbilical venous blood of cases of severe PE when compared with normotensive controls. These data provide support for alternative complement pathway involvement in the pathogenesis of severe PE and demonstrate that alternative complement activation occurs not only in the maternal but also in the fetal compartment. © 2013 John Wiley & Sons Ltd.

Complement activation cascade triggered by PEG-PL engineered nanomedicines and carbon nanotubes: The challenges ahead

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Moghimi, S.M.; Andersen, Alina Joukainen; Hashemi, S.H.

2010-01-01

reactions to certain PEG-PL engineered nanomedicines in both experimental animals and man. These reactions are classified as pseudoallergy and may be associated with cardiopulmonary disturbance and other related symptoms of anaphylaxis. Recent studies suggest that complement activation may be a contributing......, but not a rate limiting factor, in eliciting hypersensitivity reactions to such nanomedicines in sensitive individuals. This is rather surprising since PEGylated structures are generally assumed to suppress protein adsorption and blood opsonization events including complement. Here, we examine the molecular...... basis of complement activation by PEG-PL engineered nanomedicines and carbon nanotubes and discuss the challenges ahead....

Early Intra-Articular Complement Activation in Ankle Fractures

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Hagen Schmal

2014-01-01

Full Text Available Cytokine regulation possibly influences long term outcome following ankle fractures, but little is known about synovial fracture biochemistry. Eight patients with an ankle dislocation fracture were included in a prospective case series and matched with patients suffering from grade 2 osteochondritis dissecans (OCD of the ankle. All fractures needed external fixation during which joint effusions were collected. Fluid analysis was done by ELISA measuring aggrecan, bFGF, IL-1β, IGF-1, and the complement components C3a, C5a, and C5b-9. The time periods between occurrence of fracture and collection of effusion were only significantly associated with synovial aggrecan and C5b-9 levels (P<0.001. Furthermore, synovial expressions of both proteins correlated with each other (P<0.001. Although IL-1β expression was relatively low, intra-articular levels correlated with C5a (P<0.01 and serological C-reactive protein concentrations 2 days after surgery (P<0.05. Joint effusions were initially dominated by neutrophils, but the portion of monocytes constantly increased reaching 50% at day 6 after fracture (P<0.02. Whereas aggrecan and IL-1β concentrations were not different in fracture and OCD patients, bFGF, IGF-1, and all complement components were significantly higher concentrated in ankle joints with fractures (P<0.01. Complement activation and inflammatory cell infiltration characterize the joint biology following acute ankle fractures.

Complement activation on the surface of cell-derived microparticles during cardiac surgery with cardiopulmonary bypass - is retransfusion of pericardial blood harmful?

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Biró, E; van den Goor, J M; de Mol, B A; Schaap, M C; Ko, L-Y; Sturk, A; Hack, C E; Nieuwland, R

2011-01-01

To investigate whether cell-derived microparticles play a role in complement activation in pericardial blood of patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) and whether microparticles in pericardial blood contribute to systemic complement activation upon retransfusion. Pericardial blood of 13 patients was retransfused in 9 and discarded in 4 cases. Microparticles were isolated from systemic blood collected before anesthesia (T1) and at the end of CPB (T2), and from pericardial blood. The microparticles were analyzed by flow cytometry for bound complement components C1q, C4 and C3, and bound complement activator molecules C-reactive protein (CRP), serum amyloid P-component (SAP), immunoglobulin (Ig)M and IgG. Fluid-phase complement activation products (C4b/c, C3b/c) and activator molecules were determined by ELISA. Compared with systemic T1 blood, pericardial blood contained increased C4b/c and C3b/c, and increased levels of microparticles with bound complement components. In systemic T1 samples, microparticle-bound CRP, whereas in pericardial blood, microparticle-bound SAP and IgM were associated with complement activation. At the end of CPB, increased C3b/c (but not C4b/c) was present in systemic T2 blood compared with T1, while concentrations of microparticles binding complement components and of those binding complement activator molecules were similar. Concentrations of fluid-phase complement activation products and microparticles were similar in patients whether or not retransfused with pericardial blood. In pericardial blood of patients undergoing cardiac surgery with CPB, microparticles contribute to activation of the complement system via bound SAP and IgM. Retransfusion of pericardial blood, however, does not contribute to systemic complement activation.

GLUCOCORTICOSTEROIDS' EFFECT UPON THE COMPLEMENT LEVEL

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Voja Pavlovic

2001-03-01

Full Text Available The effect of high doses of cortisol upon the level of the overall complements'hemolytic activity and particular complements' components is studies. The experimentsinvolved guinea pigs of male sex of the body mass from 300 to 400 g, namelythose that have not been treated by anything so far. The doses of hydrocortisone(Hemofarm DD were also used for the experiment. The overall complements'activity was determined by testing the capabilities of a series of various solutions ofthe guinea pigs' serum to separate sheep erythrocytes that were made sensitive byrabbit anti-erythrocyte antibodies. The determination of the C1, C2, C3 and C4complements' components was done by the method of the quantitative diffusion ofthe radial type by using the Partigen blocks Behringwerke AG. The series comprised25 guinea pigs of male sex. The low cortisol level rapidly increase the overallhemolytic activity of the complements of the C1 est erase concentration. Along withthe cortisol dose increase the overall hemolytic complements' activity is dropping aswell as that of the C1, C2, C3 and C4 complements' components.

Complement Evasion by Pathogenic Leptospira.

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Fraga, Tatiana Rodrigues; Isaac, Lourdes; Barbosa, Angela Silva

2016-01-01

Leptospirosis is a neglected infectious disease caused by spirochetes from the genus Leptospira . Pathogenic microorganisms, notably those which reach the blood circulation such as Leptospira , have evolved multiple strategies to escape the host complement system, which is important for innate and acquired immunity. Leptospira avoid complement-mediated killing through: (i) recruitment of host complement regulators; (ii) acquisition of host proteases that cleave complement proteins on the bacterial surface; and, (iii) secretion of proteases that inactivate complement proteins in the Leptospira surroundings. The recruitment of host soluble complement regulatory proteins includes the acquisition of Factor H (FH) and FH-like-1 (alternative pathway), C4b-binding protein (C4BP) (classical and lectin pathways), and vitronectin (Vn) (terminal pathway). Once bound to the leptospiral surface, FH and C4BP retain cofactor activity of Factor I in the cleavage of C3b and C4b, respectively. Vn acquisition by leptospires may result in terminal pathway inhibition by blocking C9 polymerization. The second evasion mechanism lies in plasminogen (PLG) binding to the leptospiral surface. In the presence of host activators, PLG is converted to enzymatically active plasmin, which is able to degrade C3b, C4b, and C5 at the surface of the pathogen. A third strategy used by leptospires to escape from complement system is the active secretion of proteases. Pathogenic, but not saprophytic leptospires, are able to secrete metalloproteases that cleave C3 (central complement molecule), Factor B (alternative pathway), and C4 and C2 (classical and lectin pathways). The purpose of this review is to fully explore these complement evasion mechanisms, which act together to favor Leptospira survival and multiplication in the host.

Human Secretory IgM Antibodies Activate Human Complement and Offer Protection at Mucosal Surface.

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Michaelsen, T E; Emilsen, S; Sandin, R H; Granerud, B K; Bratlie, D; Ihle, O; Sandlie, I

2017-01-01

IgM molecules circulate in serum as large polymers, mainly pentamers, which can be transported by the poly-Ig receptor (pIgR) across epithelial cells to mucosal surfaces and released as secretory IgM (SIgM). The mucosal SIgM molecules have non-covalently attached secretory component (SC), which is the extracellular part of pIgR which is cleaved from the epithelial cell membrane. Serum IgM antibodies do not contain SC and have previously been shown to make a conformational change from 'a star' to a 'staple' conformation upon reaction with antigens on a cell surface, enabling them to activate complement. However, it is not clear whether SIgM similarly can induce complement activation. To clarify this issue, we constructed recombinant chimeric (mouse/human) IgM antibodies against hapten 5-iodo-4-hydroxy-3-nitro-phenacetyl (NIP) and in addition studied polyclonal IgM formed after immunization with a meningococcal group B vaccine. The monoclonal and polyclonal IgM molecules were purified by affinity chromatography on a column containing human SC in order to isolate joining-chain (J-chain) containing IgM, followed by addition of excess amounts of soluble SC to create SIgM (IgM J+ SC+). These SIgM preparations were tested for complement activation ability and shown to be nearly as active as the parental IgM J+ molecules. Thus, SIgM may offer protection against pathogens at mucosal surface by complement-mediated cell lysis or by phagocytosis mediated by complement receptors present on effector cells on mucosa. © 2016 The Foundation for the Scandinavian Journal of Immunology.

Collectin-11/MASP complex formation triggers activation of the lectin complement pathway--the fifth lectin pathway initiation complex

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Ma, Ying Jie; Skjoedt, Mikkel-Ole; Garred, Peter

2013-01-01

Collectins and ficolins are important in the clearance of endogenous and exogenous danger materials. A new human collectin-11 was recently identified in low concentration in serum in complex with mannose-binding lectin (MBL)/ficolin-associated serine proteases. Collectin-11 binds to carbohydrate...... complement complex on C. albicans. Moreover, spiking collectin-11-depleted serum, which did not mediate complement activation, with recombinant collectin-11 restored the complement activation capability. These results define collectin-11 as the fifth recognition molecule in the lectin complement pathway...

Increased Autoreactivity of the Complement-Activating Molecule Mannan-Binding Lectin in a Type 1 Diabetes Model

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Jakob Appel Østergaard

2016-01-01

Full Text Available Background. Diabetic kidney disease is the leading cause of end-stage renal failure despite intensive treatment of modifiable risk factors. Identification of new drug targets is therefore of paramount importance. The complement system is emerging as a potential new target. The lectin pathway of the complement system, initiated by the carbohydrate-recognition molecule mannan-binding lectin (MBL, is linked to poor kidney prognosis in diabetes. We hypothesized that MBL activates complement upon binding within the diabetic glomerulus. Methods. We investigated this by comparing complement deposition and activation in kidneys from streptozotocin-induced diabetic mice and healthy control mice. Results. After 20 weeks of diabetes, glomerular deposition of MBL was significantly increased. Diabetic animals had 2.0-fold higher (95% CI 1.6–2.5 immunofluorescence intensity from anti-MBL antibodies compared with controls (P<0.001. Diabetes and control groups did not differ in glomerular immunofluorescence intensity obtained by antibodies against complement factors C4, C3, and C9. However, the circulating complement activation product C3a was increased in diabetes as compared to control mice (P=0.04. Conclusion. 20 weeks of diabetes increased MBL autoreactivity in the kidney and circulating C3a concentration. Together with previous findings, these results indicate direct effects of MBL within the kidney in diabetes.

The Anticomplementary Activity of ’Fusobacterium polymorphum’ in Normal and C-4 Deficient Sources of Guinea Pig Complement.

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1977-01-12

A complement consumption assay was used to show that the anticomplementary activity of a cell wall preparation from F. polymorphum in guinea pig complement...tests with C𔃾-deficient guinea pig sera confirmed that F. polymorphum cell walls were capable of generating alternate complement pathway activity in guinea pig sera.

The lectin pathway of complement activation is a critical component of the innate immune response to pneumococcal infection

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Ali, Youssif M; Lynch, Nicholas J; Haleem, Kashif S

2012-01-01

The complement system plays a key role in host defense against pneumococcal infection. Three different pathways, the classical, alternative and lectin pathways, mediate complement activation. While there is limited information available on the roles of the classical and the alternative activation...... to pneumococcal infection and fail to opsonize Streptococcus pneumoniae in the none-immune host. This defect in complement opsonisation severely compromises pathogen clearance in the lectin pathway deficient host. Using sera from mice and humans with defined complement deficiencies, we demonstrate that mouse...... of C4. This study corroborates the essential function of MASP-2 in the lectin pathway and highlights the importance of MBL-independent lectin pathway activation in the host defense against pneumococci....

Effect of dialyzer geometry on granulocyte and complement activation.

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Schaefer, R M; Heidland, A; Hörl, W H

1987-01-01

During hemodialysis with cuprophan membranes, the complement system as well as leukocytes become activated. In order to clarify the role of dialyzer geometry, the effect of hollow-fiber versus flat-sheet dialyzers and of different surface areas on C3a generation and leukocyte degranulation was investigated. Plasma levels of leukocyte elastase in complex with alpha 1-proteinase inhibitor were significantly increased after 1 h (+55%) and 3 h (+62%) of hemodialysis with flat-sheet dialyzers as compared to hollow-fiber devices. In addition, plasma levels of lactoferrin, released from the specific granules of leukocytes during activation, were significantly higher (+42%) 3 h after the onset of dialysis treatment with flat-sheet than with hollow-fiber dialyzers. With respect to surface area, larger dialyzers tended to cause more release of leukocyte elastase as compared to dialyzers with smaller surface areas, irrespectively of the configuration of the dialyzer used. On the other hand, activation of the complement system, as measured by the generation of C3a-desarg, did not differ with both types of configurations. The same held true for leukopenia, which was almost identical for hollow-fiber and flat-sheet dialyzers. From these findings two lines of evidence emerge: First, not only the type of membrane material used in a dialyzer may influence its biocompatibility, but the geometry of the extracorporeal device also determines the degree of compatibility. Hence, the extent of leukocyte activation correlated with both configuration of the dialyzer and surface area of the membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of complement activation by dextran-coated superparamagnetic iron oxide (SPIO) nanoworms in mouse versus human serum

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Banda, Nirmal K; Mehta, Gaurav; Chao, Ying

2014-01-01

BACKGROUND: The complement system is a key component of innate immunity implicated in the neutralization and clearance of invading pathogens. Dextran coated superparamagnetic iron oxide (SPIO) nanoparticle is a promising magnetic resonance imaging (MRI) contrast agent. However, dextran SPIO has...... the mechanisms of human complement activation. Mouse data were analyzed by non-paired t-test, human data were analyzed by ANOVA followed by multiple comparisons with Student-Newman-Keuls test. RESULTS: In mouse sera, SPIO NW triggered the complement activation via the LP, whereas the AP contributes via...... the CP, but that did not affect the total level of C3 deposition on the particles. CONCLUSIONS: There were important differences and similarities in the complement activation by SPIO NW in mouse versus human sera. Understanding the mechanisms of immune recognition of nanoparticles in mouse and human...

Optimizing complement-activating antibody-based cancer immunotherapy: a feasible strategy?

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Maio Michele

2004-06-01

Full Text Available Abstract Passive immunotherapy with monoclonal antibodies (mAb targeted to specific tumor-associated antigens is amongst the most rapidly expanding approaches to biological therapy of cancer. However, until now a limited number of therapeutic mAb has demonstrated clinical efficacy in selected neoplasia. Results emerging from basic research point to a deeper characterization of specific biological features of neoplastic cells as crucial to optimize the clinical potential of therapeutic mAb, and to identify cancer patients who represent the best candidates to antibody-based immunotherapy. Focus on the tissue distribution and on the functional role of membrane complement-regulatory proteins such as Protectin (CD59, which under physiologic conditions protects tissues from Complement (C-damage, might help to optimize the efficacy of immunotherapeutic strategies based on C-activating mAb.

Crosstalk between complement and Toll-like receptor activation in relation to donor brain death and renal ischemia-reperfusion injury.

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Damman, Jeffrey; Daha, Mohamed R; van Son, Willem J; Leuvenink, Henri G; Ploeg, Rutger J; Seelen, Marc A

2011-04-01

Two central pathways of innate immunity, complement and Toll-like receptors (TLRs), play an important role in the pathogenesis of renal injury inherent to kidney transplantation. Recent findings indicate close crosstalk between complement and TLR signaling pathways. It is suggested that mitogen activated protein kinases (MAPKs) might be the key molecules linking both the complement and TLR pathways together. Complement and TLRs are important mediators of renal ischemia-reperfusion injury (IRI). Besides IRI, complement C3 can also be upregulated and activated in the kidney before transplantation as a direct result of brain death (BD) in the donor. This local upregulation and activation of complement in the donor kidney has been proven to be detrimental for renal allograft outcome. Also TLR4 and several of its major ligands are upregulated by donor BD compared to living donors. Important and in line with the observations above, kidney transplant recipients have a benefit when receiving a kidney from a TLR4 Asp299Gly/Thr399Ile genotypic donor. The role of complement and TLRs and crosstalk between these two innate immune systems in relation to renal injury during donor BD and ischemia-reperfusion are focus of this review. Future strategies to target complement and TLR activation in kidney transplantation are considered. ©2011 The Authors Journal compilation©2011 The American Society of Transplantation and the American Society of Transplant Surgeons.

Classroom Active Learning Complemented by an Online Discussion Forum to Teach Sustainability

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Dengler, Mary

2008-01-01

This paper identifies some of the pedagogical benefits of an active learning course delivery complemented by an online discussion forum to teach sustainability by evaluating the case of a geography master's course. The potential benefits and some challenges of an active learning course delivery to teach sustainability in geography and related…

Complement activation in astrocytomas: deposition of C4d and patient outcome

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Mäkelä, Katri; Helén, Pauli; Haapasalo, Hannu; Paavonen, Timo

2012-01-01

C4d is a cleavage product of complement component C4 and is considered to serve as a marker for the site of complement activation. In this study C4d staining of grade I-IV astrocytic tumors was studied to explore if there is an association between complement activation and the grade of tumor, or patient survival. Tissue micro-array samples of 102 astrocytomas were stained immunohistochemically. The material consisted of 9 pilocytic astrocytomas and 93 grade II-IV astrocytomas, of which 67 were primary resections and 26 recurrent tumors. The intensity of C4d staining as well as extent of C4d and CD34 staining were evaluated. The intensity of C4d staining was scored semiquantitatively. The extent of the staining was counted morphometrically with a point counting grid yielding a percent of C4d and CD34 positive area of the sample. The intensity and extent of C4d staining increased in grade II-IV diffusely infiltrating astrocytoma tumors in line with the malignancy grade (p = 0.034 and p = 0.016, respectively, Kruskal-Wallis test). However, C4d positive tumor area percentages were higher in grade I pilocytic astrocytomas than in grade II-IV diffusely infiltrating astrocytomas (p = 0.041, Mann–Whitney test). There was a significant correlation between CD34 positive and C4d positive endothelial area fraction in diffusely infiltrating astrocytomas (p < 0.001, Pearson correlation). In these tumors, the increasing intensity of C4d staining was also associated with worsened patient outcome (p = 0.014, log-rank test). The worsening of patient outcome and malignant progression of tumor cells seem to be connected to microenvironmental changes evoked by chronically activated complement

Complement activation in emergency department patients with severe sepsis.

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Younger, John G; Bracho, David O; Chung-Esaki, Hangyul M; Lee, Moonseok; Rana, Gurpreet K; Sen, Ananda; Jones, Alan E

2010-04-01

This study assessed the extent and mechanism of complement activation in community-acquired sepsis at presentation to the emergency department (ED) and following 24 hours of quantitative resuscitation. A prospective pilot study of patients with severe sepsis and healthy controls was conducted among individuals presenting to a tertiary care ED. Resuscitation, including antibiotics and therapies to normalize central venous and mean arterial pressure (MAP) and central venous oxygenation, was performed on all patients. Serum levels of Factor Bb (alternative pathway), C4d (classical and mannose-binding lectin [MBL] pathway), C3, C3a, and C5a were determined at presentation and 24 hours later among patients. Twenty patients and 10 healthy volunteer controls were enrolled. Compared to volunteers, all proteins measured were abnormally higher among septic patients (C4d 3.5-fold; Factor Bb 6.1-fold; C3 0.8-fold; C3a 11.6-fold; C5a 1.8-fold). Elevations in C5a were most strongly correlated with alternative pathway activation. Surprisingly, a slight but significant inverse relationship between illness severity (by sequential organ failure assessment [SOFA] score) and C5a levels at presentation was noted. Twenty-four hours of structured resuscitation did not, on average, affect any of the mediators studied. Patients with community-acquired sepsis have extensive complement activation, particularly of the alternative pathway, at the time of presentation that was not significantly reversed by 24 hours of aggressive resuscitation.

Complement lysis activity in autologous plasma is associated with lower viral loads during the acute phase of HIV-1 infection.

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Michael Huber

2006-11-01

Full Text Available BACKGROUND: To explore the possibility that antibody-mediated complement lysis contributes to viremia control in HIV-1 infection, we measured the activity of patient plasma in mediating complement lysis of autologous primary virus. METHODS AND FINDINGS: Sera from two groups of patients-25 with acute HIV-1 infection and 31 with chronic infection-were used in this study. We developed a novel real-time PCR-based assay strategy that allows reliable and sensitive quantification of virus lysis by complement. Plasma derived at the time of virus isolation induced complement lysis of the autologous virus isolate in the majority of patients. Overall lysis activity against the autologous virus and the heterologous primary virus strain JR-FL was higher at chronic disease stages than during the acute phase. Most strikingly, we found that plasma virus load levels during the acute but not the chronic infection phase correlated inversely with the autologous complement lysis activity. Antibody reactivity to the envelope (Env proteins gp120 and gp41 were positively correlated with the lysis activity against JR-FL, indicating that anti-Env responses mediated complement lysis. Neutralization and complement lysis activity against autologous viruses were not associated, suggesting that complement lysis is predominantly caused by non-neutralizing antibodies. CONCLUSIONS: Collectively our data provide evidence that antibody-mediated complement virion lysis develops rapidly and is effective early in the course of infection; thus it should be considered a parameter that, in concert with other immune functions, steers viremia control in vivo.

Arthrogenicity of type II collagen monoclonal antibodies associated with complement activation and antigen affinity.

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Koobkokkruad, Thongchai; Kadotani, Tatsuya; Hutamekalin, Pilaiwanwadee; Mizutani, Nobuaki; Yoshino, Shin

2011-11-04

The collagen antibody-induced arthritis (CAIA) model, which employs a cocktail of monoclonal antibodies (mAbs) to type II collagen (CII), has been widely used for studying the pathogenesis of autoimmune arthritis. In this model, not all mAbs to CII are capable of inducing arthritis because one of the initial events is the formation of collagen-antibody immune complexes on the cartilage surface or in the synovium, and subsequent activation of the complement by the complexes induces arthritis, suggesting that a combination of mAbs showing strong ability to bind mouse CII and activate the complement may effectively induce arthritis in mice. In the present study, we examined the relationship between the induction of arthritis by the combination of IgG2a (CII-6 and C2A-12), IgG2b (CII-3, C2B-14 and C2B-16) and IgM (CM-5) subclones of monoclonal antibodies (mAb) of anti-bovine or chicken CII and the ability of mAbs to activate complement and bind mouse CII. DBA/1J mice were injected with several combinations of mAbs followed by lipopolysaccharide. Furthermore, the ability of mAbs to activate the complement and bind mouse CII was examined by ELISA. First, DBA/1J mice were injected with the combined 4 mAbs (CII-3, CII-6, C2B-14, and CM-5) followed by lipopolysaccharide, resulting in moderate arthritis. Excluding one of the mAbs, i.e., using only CII-3, CII-6, and C2B-14, induced greater inflammation of the joints. Next, adding C2A-12 but not C2B-16 to these 3 mAbs produced more severe arthritis. A combination of five clones, consisting of all 5 mAbs, was less effective. Histologically, mice given the newly developed 4-clone cocktail had marked proliferation of synovial tissues, massive infiltration by inflammatory cells, and severe destruction of cartilage and bone. Furthermore, 4 of the 6 clones (CII-3, CII-6, C2B-14, and C2A-12) showed not only a strong cross-reaction with mouse CII but also marked activation of the complement in vitro. The combination of 4 mAbs showing

Arthrogenicity of type II collagen monoclonal antibodies associated with complement activation and antigen affinity

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Mizutani Nobuaki

2011-11-01

Full Text Available Abstract Background The collagen antibody-induced arthritis (CAIA model, which employs a cocktail of monoclonal antibodies (mAbs to type II collagen (CII, has been widely used for studying the pathogenesis of autoimmune arthritis. In this model, not all mAbs to CII are capable of inducing arthritis because one of the initial events is the formation of collagen-antibody immune complexes on the cartilage surface or in the synovium, and subsequent activation of the complement by the complexes induces arthritis, suggesting that a combination of mAbs showing strong ability to bind mouse CII and activate the complement may effectively induce arthritis in mice. In the present study, we examined the relationship between the induction of arthritis by the combination of IgG2a (CII-6 and C2A-12, IgG2b (CII-3, C2B-14 and C2B-16 and IgM (CM-5 subclones of monoclonal antibodies (mAb of anti-bovine or chicken CII and the ability of mAbs to activate complement and bind mouse CII. Methods DBA/1J mice were injected with several combinations of mAbs followed by lipopolysaccharide. Furthermore, the ability of mAbs to activate the complement and bind mouse CII was examined by ELISA. Results First, DBA/1J mice were injected with the combined 4 mAbs (CII-3, CII-6, C2B-14, and CM-5 followed by lipopolysaccharide, resulting in moderate arthritis. Excluding one of the mAbs, i.e., using only CII-3, CII-6, and C2B-14, induced greater inflammation of the joints. Next, adding C2A-12 but not C2B-16 to these 3 mAbs produced more severe arthritis. A combination of five clones, consisting of all 5 mAbs, was less effective. Histologically, mice given the newly developed 4-clone cocktail had marked proliferation of synovial tissues, massive infiltration by inflammatory cells, and severe destruction of cartilage and bone. Furthermore, 4 of the 6 clones (CII-3, CII-6, C2B-14, and C2A-12 showed not only a strong cross-reaction with mouse CII but also marked activation of the

Abnormal Complement Activation and Inflammation in the Pathogenesis of Retinopathy of Prematurity

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Sonika Rathi

2017-12-01

Full Text Available Retinopathy of prematurity (ROP is a neurovascular complication in preterm babies, leading to severe visual impairment, but the underlying mechanisms are yet unclear. The present study aimed at unraveling the molecular mechanisms underlying the pathogenesis of ROP. A comprehensive screening of candidate genes in preterms with ROP (n = 189 and no-ROP (n = 167 was undertaken to identify variants conferring disease susceptibility. Allele and genotype frequencies, linkage disequilibrium and haplotypes were analyzed to identify the ROP-associated variants. Variants in CFH (p = 2.94 × 10−7, CFB (p = 1.71 × 10−5, FBLN5 (p = 9.2 × 10−4, CETP (p = 2.99 × 10−5, and CXCR4 (p = 1.32 × 10−8 genes exhibited significant associations with ROP. Further, a quantitative assessment of 27 candidate proteins and cytokines in the vitreous and tear samples of babies with severe ROP (n = 30 and congenital cataract (n = 30 was undertaken by multiplex bead arrays and further validated by western blotting and zymography. Significant elevation and activation of MMP9 (p = 0.038, CFH (p = 2.24 × 10−5, C3 (p = 0.05, C4 (p = 0.001, IL-1ra (p = 0.0019, vascular endothelial growth factor (VEGF (p = 0.0027, and G-CSF (p = 0.0099 proteins were observed in the vitreous of ROP babies suggesting an increased inflammation under hypoxic condition. Along with inflammatory markers, activated macrophage/microglia were also detected in the vitreous of ROP babies that secreted complement component C3, VEGF, IL-1ra, and MMP-9 under hypoxic stress in a cell culture model. Increased expression of the inflammatory markers like the IL-1ra (p = 0.014, MMP2 (p = 0.0085, and MMP-9 (p = 0.03 in the tears of babies at different stages of ROP further demonstrated their potential role in disease progression. Based on these findings, we conclude that increased complement activation in the

Human stem cell-derived retinal epithelial cells activate complement via collectin 11 in response to stress

DEFF Research Database (Denmark)

Fanelli, Giorgia; Gonzalez-Cordero, Anai; Gardner, Peter J

2017-01-01

Age-related macular degeneration (AMD) is a major cause of blindness and is associated with complement dysregulation. The disease is a potential target for stem cell therapy but success is likely to be limited by the inflammatory response. We investigated the innate immune properties of human ind...

Complement and thrombosis in the antiphospholipid syndrome.

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Oku, Kenji; Nakamura, Hiroyuki; Kono, Michihiro; Ohmura, Kazumasa; Kato, Masaru; Bohgaki, Toshiyuki; Horita, Tetsuya; Yasuda, Shinsuke; Amengual, Olga; Atsumi, Tatsuya

2016-10-01

The involvement of complement activation in the pathophysiology of antiphospholipid syndrome (APS) was first reported in murine models of antiphospholipid antibody (aPL)-related pregnancy morbidities. We previously reported that complement activation is prevalent and may function as a source of procoagulant cell activation in the sera of APS patients. Recently, autoantibodies against C1q, a component of complement 1, were reported to be correlated with complement activation in systemic lupus erythematosus. These antibodies target neoepitopes of deformed C1q bound to various molecules (i.e., anionic phospholipids) and induce accelerated complement activation. We found that anti-C1q antibodies are more frequently detected in primary APS patients than in control patients and in refractory APS patients with repeated thrombotic events. The titer of anti-C1q antibodies was significantly higher in refractory APS patients than in APS patients without flare. The binding of C1q to anionic phospholipids may be associated with the surge in complement activation in patients with anti-C1q antibodies when triggered by 'second-hit' biological stressors such as infection. Such stressors will induce overexpression of anionic phospholipids, with subsequent increases in deformed C1q that is targeted by anti-C1q antibodies. Copyright © 2016. Published by Elsevier B.V.

Tumour exosomes display different differential mechanical and complement activation properties dependent on malignant state: implications in endothelial leakiness

DEFF Research Database (Denmark)

Whitehead, Bradley Joseph; Wu, Linping; Hvam, Michael Lykke

2015-01-01

(QNM AFM) to determine size and nanomechanical properties. Effect of HCV-29, T24 and FL3 exosomes on human umbilical vein endothelial cell (HUVEC) monolayer integrity was determined by transendothelial electrical resistance (TEER) measurements and transport was determined by flow cytometry. Complement......). Malignant cell-derived exosomes activated complement through calcium-sensitive pathways in a concentration-dependent manner. Conclusions : Malignant (metastatic and non-metastatic) cell line exosomes display a markedly reduced stiffness and adhesion but an increased complement activation compared to non...

Citrem Modulates Internal Nanostructure of Glyceryl Monooleate Dispersions and Bypasses Complement Activation

DEFF Research Database (Denmark)

Wibroe, Peter P; Mat Azmi, Intan Diana Binti; Nilsson, Christa

2015-01-01

Lyotropic non-lamellar liquid crystalline (LLC) aqueous nanodispersions hold a great promise in drug solubilization and delivery, but these nanosystems often induce severe hemolysis and complement activation, which limit their applications for safe intravenous administration. Here, we engineer an...

Nanomedicine and the complement paradigm.

Science.gov (United States)

Moghimi, S Moein; Farhangrazi, Z Shadi

2013-05-01

The role of complement in idiosyncratic reactions to nanopharmaceutical infusion is receiving increasing attention. We discuss this in relation to nanopharmaceutical development and the possible use of complement inhibitors to prevent related adverse reactions. We further call on initiation of genetic association studies to unravel the genetic basis of nanomedicine infusion-related adverse responses, since most of the polymorphic genes in the genome belong to the immune system. In this paper, idiosyncratic reactions based on complement activation are discussed in the context of newly available complement inhibitors. Copyright © 2013 Elsevier Inc. All rights reserved.

Thrombin activatable fibrinolysis inhibitor (TAFI) - A possible link between coagulation and complement activation in the antiphospholipid syndrome (APS).

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Grosso, Giorgia; Vikerfors, Anna; Woodhams, Barry; Adam, Mariette; Bremme, Katarina; Holmström, Margareta; Ågren, Anna; Eelde, Anna; Bruzelius, Maria; Svenungsson, Elisabet; Antovic, Aleksandra

2017-10-01

Thrombosis and complement activation are pathogenic features of antiphospholipid syndrome (APS). Their molecular link is Plasma carboxypeptidase-B, also known as thrombin activatable fibrinolysis inhibitor (TAFIa), which plays a dual role: anti-fibrinolytic, by cleaving carboxyl-terminal lysine residues from partially degraded fibrin, and anti-inflammatory, by downregulating complement anaphylatoxins C3a and C5a. To investigate the levels of TAFI (proenzyme) and TAFIa (active enzyme) in relation to complement activation, fibrin clot permeability and fibrinolytic function in clinical and immunological subsets of 52 APS patients and 15 controls. TAFI (pAPS patients compared to controls. Furthermore, TAFIa was increased (pAPS patients affected by arterial thrombosis compared to other APS-phenotypes. Positive associations were found between TAFI and age, fibrinogen and C5a, and between TAFIa and age, fibrinogen and thrombomodulin. TAFI and TAFIa levels were increased in patients with APS as a potential response to complement activation. Interestingly, TAFI activation was associated with arterial thrombotic APS manifestations. Thus, TAFIa may be considered a novel biomarker for arterial thrombosis in APS. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dengue-Immune Humans Have Higher Levels of Complement-Independent Enhancing Antibody than Complement-Dependent Neutralizing Antibody.

Science.gov (United States)

Yamanaka, Atsushi; Konishi, Eiji

2017-09-25

Dengue is the most important arboviral disease worldwide. We previously reported that most inhabitants of dengue-endemic countries who are naturally immune to the disease have infection-enhancing antibodies whose in vitro activity does not decrease in the presence of complement (complement-independent enhancing antibodies, or CiEAb). Here, we compared levels of CiEAb and complement-dependent neutralizing antibodies (CdNAb) in dengue-immune humans. A typical antibody dose-response pattern obtained in our assay system to measure the balance between neutralizing and enhancing antibodies showed both neutralizing and enhancing activities depending on serum dilution factor. The addition of complement to the assay system increased the activity of neutralizing antibodies at lower dilutions, indicating the presence of CdNAb. In contrast, similar dose-response curves were obtained with and without complement at higher dilutions, indicating higher levels of CiEAb than CdNAb. For experimental support for the higher CiEAb levels, a cocktail of mouse monoclonal antibodies against dengue virus type 1 was prepared. The antibody dose-response curves obtained in this assay, with or without complement, were similar to those obtained with human serum samples when a high proportion of D1-V-3H12 (an antibody exhibiting only enhancing activity and thus a model for CiEAb) was used in the cocktail. This study revealed higher-level induction of CiEAb than CdNAb in humans naturally infected with dengue viruses.

A teleost CD46 is involved in the regulation of complement activation and pathogen infection.

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Li, Mo-Fei; Sui, Zhi-Hai; Sun, Li

2017-11-03

In mammals, CD46 is involved in the inactivation of complement by factor I (FI). In teleost, study on the function of CD46 is very limited. In this study, we examined the immunological property of a CD46 molecule (CsCD46) from tongue sole, a teleost species with important economic value. We found that recombinant CsCD46 (rCsCD46) interacted with FI and inhibited complement activation in an FI-dependent manner. rCsCD46 also interacted with bacterial pathogens via a different mechanism to that responsible for the FI interaction, involving different rCsCD46 sites. Cellular study showed that CsCD46 was expressed on peripheral blood leukocytes (PBL) and protected the cells against the killing effect of complement. When the CsCD46 on PBL was blocked by antibody before incubation of the cells with bacterial pathogens, cellular infection was significantly reduced. Consistently, when tongue sole were infected with bacterial pathogens in the presence of rCsCD46, tissue dissemination and survival of the pathogens were significantly inhibited. These results provide the first evidence to indicate that CD46 in teleosts negatively regulates complement activation via FI and protects host cells from complement-induced damage, and that CD46 is required for optimal bacterial infection probably by serving as a receptor for the bacteria.

Characterization of the third component of complement (C3) after activation by cigarette smoke

International Nuclear Information System (INIS)

Kew, R.R.; Ghebrehiwet, B.; Janoff, A.

1987-01-01

Activation of lung complement by tobacco smoke may be an important pathogenetic factor in the development of pulmonary emphysema in smokers. We previously showed that cigarette smoke can modify C3 and activate the alternative pathway of complement in vitro. However, the mechanism of C3 activation was not fully delineated in these earlier studies. In the present report, we show that smoke-treated C3 induces cleavage of the alternative pathway protein, Factor B, when added to serum containing Mg-EGTA. This effect of cigarette smoke is specific for C3 since smoke-treated C4, when added to Mg-EGTA-treated serum, fails to activate the alternative pathway and fails to induce Factor B cleavage. Smoke-modified C3 no longer binds significant amounts of [ 14 C]methylamine (as does native C3), and relatively little [ 14 C]methylamine is incorporated into its alpha-chain. Thus, prior internal thiolester bond cleavage appears to have occurred in C3 activated by cigarette smoke. Cigarette smoke components also induce formation of noncovalently associated, soluble C3 multimers, with a Mr ranging from 1 to 10 million. However, prior cleavage of the thiolester bond in C3 with methylamine prevents the subsequent formation of these smoke-induced aggregates. These data indicate that cigarette smoke activates the alternative pathway of complement by specifically modifying C3 and that these modifications include cleavage of the thiolester bond in C3 and formation of noncovalently linked C3 multimers

Activation of the lectin pathway of complement in experimental human keratitis with Pseudomonas aeruginosa.

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Osthoff, Michael; Brown, Karl D; Kong, David C M; Daniell, Mark; Eisen, Damon P

2014-01-01

Pseudomonas aeruginosa (P. aeruginosa) microbial keratitis (MK) is a sight-threatening disease. Previous animal studies have identified an important contribution of the complement system to the clearance of P. aeruginosa infection of the cornea. Mannose-binding lectin (MBL), a pattern recognition receptor of the lectin pathway of complement, has been implicated in the host defense against P. aeruginosa. However, studies addressing the role of the lectin pathway in P. aeruginosa MK are lacking. Hence, we sought to determine the activity of the lectin pathway in human MK caused by P. aeruginosa. Primary human corneal epithelial cells (HCECs) from cadaveric donors were exposed to two different P. aeruginosa strains. Gene expression of interleukin (IL)-6, IL-8, MBL, and other complement proteins was determined by reverse transcription-polymerase chain reaction (RT-PCR) and MBL synthesis by enzyme-linked immunosorbent assay and intracellular flow cytometry. MBL gene expression was not detected in unchallenged HCECs. Exposure of HCECs to P. aeruginosa resulted in rapid induction of the transcriptional expression of MBL, IL-6, and IL-8. In addition, expression of several complement proteins of the classical and lectin pathways, but not the alternative pathway, were upregulated after 5 h of challenge, including MBL-associated serine protease 1. However, MBL protein secretion was not detectable 18 h after challenge with P. aeruginosa. MK due to P. aeruginosa triggers activation of MBL and the lectin pathway of complement. However, the physiologic relevance of this finding is unclear, as corresponding MBL oligomer production was not observed.

Lectin Pathway of Complement Activation Is Associated with Vulnerability of Atherosclerotic Plaques

DEFF Research Database (Denmark)

Fumagalli, Stefano; Perego, Carlo; Zangari, Rosalia

2017-01-01

Inflammatory mechanisms may be involved in atherosclerotic plaque rupture. By using a novel histology-based method to quantify plaque instability here, we assess whether lectin pathway (LP) of complement activation, a major inflammation arm, could represent an index of plaque instability. Plaques...

Bothrops asper snake venom and its metalloproteinase BaP–1 activate the complement system. Role in leucocyte recruitment

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Sandra H. P. Farsky

2000-01-01

Full Text Available The venom of the snake Bothrops asper, the most important poisonous snake in Central America, evokes an inflammatory response, the mechanisms of which are not well characterized. The objectives of this study were to investigate whether B. asper venom and its purified toxins – phospholipases and metalloproteinase – activate the complement system and the contribution of the effect on leucocyte recruitment. In vitro chemotaxis assays were performed using Boyden's chamber model to investigate the ability of serum incubated with venom and its purified toxins to induce neutrophil migration. The complement consumption by the venom was evaluated using an in vitro haemolytic assay. The importance of complement activation by the venom on neutrophil migration was investigated in vivo by injecting the venom into the peritoneal cavity of C5-deficient mice. Data obtained demonstrated that serum incubated with crude venom and its purified metalloproteinase BaP–1 are able to induce rat neutrophil chemotaxis, probably mediated by agent(s derived from the complement system. This hypothesis was corroborated by the capacity of the venom to activate this system in vitro. The involvement of C5a in neutrophil chemotaxis induced by venom-activated serum was demonstrated by abolishing migration when neutrophils were pre-incubated with antirat C5a receptor antibody. The relevance of the complement system in in vivo leucocyte mobilization was further demonstrated by the drastic decrease of this response in C5-deficient mice. Pre-incubation of serum with the soluble human recombinant complement receptor type 1 (sCR 1 did not prevent the response induced by the venom, but abolished the migration evoked by metalloproteinase-activated serum. These data show the role of the complement system in bothropic envenomation and the participation of metalloproteinase in the effect. Also, they suggest that the venom may contain other component(s which can cause direct activation

Complement: Alive and Kicking Nanomedicines

DEFF Research Database (Denmark)

Andersen, Alina Joukainen; Hashemi, S.H.; Andresen, Thomas Lars

2009-01-01

Administration of liposome- and polymer-based clinical nanomedicines, as well as many other proposed multifunctional nanoparticles, often triggers hypersensitivity reactions without the involvement of IgE. These anaphylactic reactions are believed to be secondary to activation of the complement...... their procoagulant activity, and has the capacity to elicit non-lytic stimulatory responses from vascular endothelial cells. Here we discuss the molecular basis of complement activation by liposomes, including poly(ethylene glycol) coated vesicles, and other related lipid-based and phospholipid-poly(ethylene glycol...

Complementing the sugar code: role of GAGs and sialic acid in complement regulation

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Alex eLangford-Smith

2015-02-01

Full Text Available Sugar molecules play a vital role on both microbial and mammalian cells, where they are involved in cellular communication, govern microbial virulence and modulate host immunity and inflammatory responses. The complement cascade, as part of a host’s innate immune system, is a potent weapon against invading bacteria but has to be tightly regulated to prevent inappropriate attack and damage to host tissues. A number of complement regulators, such as factor H and properdin, interact with sugar molecules, such as glycosaminoglycans and sialic acid, on host and pathogen membranes and direct the appropriate complement response by either promoting the binding of complement activators or inhibitors. The binding of these complement regulators to sugar molecules can vary from location to location, due to their different specificities and because distinct structural and functional subpopulations of sugars are found in different human organs, such as the brain, kidney and eye. This review will cover recent studies that have provided important new insights into the role of glycosaminoglycans and sialic acid in complement regulation and how sugar recognition may be compromised in disease

Complement Activation in Arterial and Venous Thrombosis is Mediated by Plasmin

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Jonathan H. Foley

2016-03-01

Full Text Available Thrombus formation leading to vaso-occlusive events is a major cause of death, and involves complex interactions between coagulation, fibrinolytic and innate immune systems. Leukocyte recruitment is a key step, mediated partly by chemotactic complement activation factors C3a and C5a. However, mechanisms mediating C3a/C5a generation during thrombosis have not been studied. In a murine venous thrombosis model, levels of thrombin–antithrombin complexes poorly correlated with C3a and C5a, excluding a central role for thrombin in C3a/C5a production. However, clot weight strongly correlated with C5a, suggesting processes triggered during thrombosis promote C5a generation. Since thrombosis elicits fibrinolysis, we hypothesized that plasmin activates C5 during thrombosis. In vitro, the catalytic efficiency of plasmin-mediated C5a generation greatly exceeded that of thrombin or factor Xa, but was similar to the recognized complement C5 convertases. Plasmin-activated C5 yielded a functional membrane attack complex (MAC. In an arterial thrombosis model, plasminogen activator administration increased C5a levels. Overall, these findings suggest plasmin bridges thrombosis and the immune response by liberating C5a and inducing MAC assembly. These new insights may lead to the development of strategies to limit thrombus formation and/or enhance resolution.

Decreased material-activation of the complement system using low-energy plasma polymerized poly(vinyl pyrrolidone) coatings

DEFF Research Database (Denmark)

Andersen, T.E.; Kolmos, H.J.; Palarasah, Yaseelan

2011-01-01

In the current study we investigate the activation of blood complement on medical device silicone rubber and present a plasma polymerized vinyl pyrrolidone (ppVP) coating which strongly decreases surface-activation of the blood complement system. We show that uncoated silicone and polystyrene...... surface. The ppVP surface is furthermore characterized physically and chemically using scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR), which indicates preservation of chemical functionality by the applied plasma process. Overall, the pp...

Cholesterol Crystals Activate the Lectin Complement Pathway via Ficolin-2 and Mannose-Binding Lectin

DEFF Research Database (Denmark)

Pilely, Katrine; Rosbjerg, Anne; Genster, Ninette

2016-01-01

Cholesterol crystals (CC) play an essential role in the formation of atherosclerotic plaques. CC activate the classical and the alternative complement pathways, but the role of the lectin pathway is unknown. We hypothesized that the pattern recognition molecules (PRMs) from the lectin pathway bind...... CC and function as an upstream innate inflammatory signal in the pathophysiology of atherosclerosis. We investigated the binding of the PRMs mannose-binding lectin (MBL), ficolin-1, ficolin-2, and ficolin-3, the associated serine proteases, and complement activation products to CC in vitro using...... recognize CC and provides evidence for an important role for this pathway in the inflammatory response induced by CC in the pathophysiology of atherosclerosis....

Complement activation and formation of the membrane attack complex on serogroup B Neisseria meningitidis in the presence or absence of serum bactericidal activity

NARCIS (Netherlands)

Drogari-Apiranthitou, M.; Kuijper, E. J.; Dekker, N. [=Nick; Dankert, J.

2002-01-01

Encapsulated meningococci are complement sensitive only in the presence of bactericidal antibodies by yet-unexplored mechanisms. The objective of this study was to investigate the involvement of major bacterial surface constituents on complement activation and membrane attack complex (MAC) formation

Hijacking Complement Regulatory Proteins for Bacterial Immune Evasion.

Science.gov (United States)

Hovingh, Elise S; van den Broek, Bryan; Jongerius, Ilse

2016-01-01

The human complement system plays an important role in the defense against invading pathogens, inflammation and homeostasis. Invading microbes, such as bacteria, directly activate the complement system resulting in the formation of chemoattractants and in effective labeling of the bacteria for phagocytosis. In addition, formation of the membrane attack complex is responsible for direct killing of Gram-negative bacteria. In turn, bacteria have evolved several ways to evade complement activation on their surface in order to be able to colonize and invade the human host. One important mechanism of bacterial escape is attraction of complement regulatory proteins to the microbial surface. These molecules are present in the human body for tight regulation of the complement system to prevent damage to host self-surfaces. Therefore, recruitment of complement regulatory proteins to the bacterial surface results in decreased complement activation on the microbial surface which favors bacterial survival. This review will discuss recent advances in understanding the binding of complement regulatory proteins to the bacterial surface at the molecular level. This includes, new insights that have become available concerning specific conserved motives on complement regulatory proteins that are favorable for microbial binding. Finally, complement evasion molecules are of high importance for vaccine development due to their dominant role in bacterial survival, high immunogenicity and homology as well as their presence on the bacterial surface. Here, the use of complement evasion molecules for vaccine development will be discussed.

Complement Activation by Ceramide Transporter Proteins

NARCIS (Netherlands)

Bode, G.H.; Losen, M.; Buurman, W.A.; Veerhuis, R.; Molenaar, P.C.; Steinbusch, H.W.M.; De Baets, M.H.; Daha, MR; Martinez-Martinez, P.

2014-01-01

C1q is the initiator of the classical complement pathway and, as such, is essential for efficient opsonization and clearance of pathogens, altered self-structures, and apoptotic cells. The ceramide transporter protein (CERT) and its longer splicing isoform CERTL are known to interact with

Zonulin as prehaptoglobin2 regulates lung permeability and activates the complement system.

Science.gov (United States)

Rittirsch, Daniel; Flierl, Michael A; Nadeau, Brian A; Day, Danielle E; Huber-Lang, Markus S; Grailer, Jamison J; Zetoune, Firas S; Andjelkovic, Anuska V; Fasano, Alessio; Ward, Peter A

2013-06-15

Zonulin is a protein involved in the regulation of tight junctions (TJ) in epithelial or endothelial cells. Zonulin is known to affect TJ in gut epithelial cells, but little is known about its influences in other organs. Prehaptoglobin2 has been identified as zonulin and is related to serine proteases (MASPs, C1qrs) that activate the complement system. The current study focused on the role of zonulin in development of acute lung injury (ALI) in C57BL/6 male mice following intrapulmonary deposition of IgG immune complexes. A zonulin antagonist (AT-1001) and a related peptide with permeability agonist activities (AT-1002) were employed and given intratracheally or intravenously. Also, zonulin was blocked in lung with a neutralizing antibody. In a dose-dependent manner, AT-1001 or zonulin neutralizing antibody attenuated the intensity of ALI (as quantitated by albumin leak, neutrophil accumulation, and proinflammatory cytokines). A similar pattern was found using the bacterial lipopolysaccharide model of ALI. Using confocal microscopy on sections of injured lungs, staining patterns for TJ proteins were discontinuous, reduced, and fragmented. As expected, the leak of blood products into the alveolar space confirmed the passage of 3 and 20 kDa dextran, and albumin. In contrast to AT-1001, application of the zonulin agonist AT-1002 intensified ALI. Zonulin both in vitro and in vivo induced generation of complement C3a and C5a. Collectively, these data suggest that zonulin facilitates development of ALI both by enhancing albumin leak and complement activation as well as increased buildup of neutrophils and cytokines during development of ALI.

Human Properdin Opsonizes Nanoparticles and Triggers a Potent Pro-inflammatory Response by Macrophages without Involving Complement Activation

Science.gov (United States)

Kouser, Lubna; Paudyal, Basudev; Kaur, Anuvinder; Stenbeck, Gudrun; Jones, Lucy A.; Abozaid, Suhair M.; Stover, Cordula M.; Flahaut, Emmanuel; Sim, Robert B.; Kishore, Uday

2018-01-01

Development of nanoparticles as tissue-specific drug delivery platforms can be considerably influenced by the complement system because of their inherent pro-inflammatory and tumorigenic consequences. The complement activation pathways, and its recognition subcomponents, can modulate clearance of the nanoparticles and subsequent inflammatory response and thus alter the intended translational applications. Here, we report, for the first time, that human properdin, an upregulator of the complement alternative pathway, can opsonize functionalized carbon nanotubes (CNTs) via its thrombospondin type I repeat (TSR) 4 and 5. Binding of properdin and TSR4+5 is likely to involve charge pattern/polarity recognition of the CNT surface since both carboxymethyl cellulose-coated carbon nanotubes (CMC-CNT) and oxidized (Ox-CNT) bound these proteins well. Properdin enhanced the uptake of CMC-CNTs by a macrophage cell line, THP-1, mounting a robust pro-inflammatory immune response, as revealed by qRT-PCR, multiplex cytokine array, and NF-κB nuclear translocation analyses. Properdin can be locally synthesized by immune cells in an inflammatory microenvironment, and thus, its interaction with nanoparticles is of considerable importance. In addition, recombinant TSR4+5 coated on the CMC-CNTs inhibited complement consumption by CMC-CNTs, suggesting that nanoparticle decoration with TSR4+5, can be potentially used as a complement inhibitor in a number of pathological contexts arising due to exaggerated complement activation. PMID:29483907

Plasma complement and vascular complement deposition in patients with coronary artery disease with and without inflammatory rheumatic diseases

Science.gov (United States)

2017-01-01

Purpose Inflammatory rheumatic diseases (IRD) are associated with accelerated coronary artery disease (CAD), which may result from both systemic and vascular wall inflammation. There are indications that complement may be involved in the pathogenesis of CAD in Systemic Lupus Erythematosus (SLE) and Rheumatoid Arthritis (RA). This study aimed to evaluate the associations between circulating complement and complement activation products with mononuclear cell infiltrates (MCI, surrogate marker of vascular inflammation) in the aortic media and adventitia in IRDCAD and non-IRDCAD patients undergoing coronary artery bypass grafting (CABG). Furthermore, we compared complement activation product deposition patterns in rare aorta adventitial and medial biopsies from SLE, RA and non-IRD patients. Methods We examined plasma C3 (p-C3) and terminal complement complexes (p-TCC) in 28 IRDCAD (SLE = 3; RA = 25), 52 non-IRDCAD patients, and 32 IRDNo CAD (RA = 32) from the Feiring Heart Biopsy Study. Aortic biopsies taken from the CAD only patients during CABG were previously evaluated for adventitial MCIs. The rare aortic biopsies from 3 SLE, 3 RA and 3 non-IRDCAD were assessed for the presence of C3 and C3d using immunohistochemistry. Results IRDCAD patients had higher p-TCC than non-IRDCAD or IRDNo CAD patients (prheumatic disease, and, in particular, SLE with the complement system. Exaggerated systemic and vascular complement activation may accelerate CVD, serve as a CVD biomarker, and represent a target for new therapies. PMID:28362874

CFH Y402H polymorphism and the complement activation product C5a: effects on NF-κB activation and inflammasome gene regulation.

Science.gov (United States)

Cao, Sijia; Wang, Jay Ching Chieh; Gao, Jiangyuan; Wong, Matthew; To, Elliott; White, Valerie A; Cui, Jing Z; Matsubara, Joanne A

2016-05-01

The Y402H polymorphism in the complement factor H (CFH) gene is an important risk factor for age-related macular degeneration (AMD). Complement activation products and proinflammatory cytokines are associated with this polymorphism at the systemic level, but less is known of the associations in the outer retina of the genotyped eye. Here we investigate complement activation products and their role in nuclear factor (NF)-κB activation and gene expression of the NLRP3 inflammasome pathway. Postmortem donor eyes were genotyped for the CFH Y402H polymorphism and assessed for complement C3a, C5a, interleukin (IL)-18 and tumour necrosis factor (TNF)-α. ARPE19 cells were stimulated basolaterally with C5a or TNF-α in polarised cultures. NF-κB activation was assessed with a reporter cell line. Gene expression of inflammasome-related (NLRP3, caspase-1, IL-1β and IL-18) and classic inflammatory (IL-6 and IL-8) genes was studied. The distribution of inflammasome products, IL-1β and IL-18, was studied in postmortem donor eyes with AMD pathologies. Eyes with the homozygous at-risk variant demonstrated higher levels of C5a, IL-18 and TNF-α in Bruch's membrane and choroid. C5a promoted NF-κB activation and upregulation of IL-18 in polarised ARPE19. TNF-α promoted NF-κB activation and gene expression of caspase-1, IL-1β, IL-18, IL-6 and IL-8, but downregulated NLRP3. In eyes with geographic atrophy, strong immunoreactivity was observed for inflammasome products IL-1β and IL-18 compared with age-matched controls. The at-risk polymorphism of the CFH Y402H may contribute to AMD disease process through increased complement and NF-κB activation, and the upregulation of IL-18, a product of inflammasome activation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

complement C3, Complement C4 and C-reactive protein

African Journals Online (AJOL)

ajl yemi

2011-12-19

Dec 19, 2011 ... (IL-6), E-selectin and P-selectin (Perlstein and Lee,. 2006). Studies have ... of cigarette smoke causes complement activation which is in turn ..... are decreased by long term smoking cessation in male smokers. Prevent. Med.

Autocrine Effects of Tumor-Derived Complement

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Min Soon Cho

2014-03-01

Full Text Available We describe a role for the complement system in enhancing cancer growth. Cancer cells secrete complement proteins that stimulate tumor growth upon activation. Complement promotes tumor growth via a direct autocrine effect that is partially independent of tumor-infiltrating cytotoxic T cells. Activated C5aR and C3aR signal through the PI3K/AKT pathway in cancer cells, and silencing the PI3K or AKT gene in cancer cells eliminates the progrowth effects of C5aR and C3aR stimulation. In patients with ovarian or lung cancer, higher tumoral C3 or C5aR mRNA levels were associated with decreased overall survival. These data identify a role for tumor-derived complement proteins in promoting tumor growth, and they therefore have substantial clinical and therapeutic implications.

P-I Snake Venom Metalloproteinase Is Able to Activate the Complement System by Direct Cleavage of Central Components of the Cascade

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Pidde-Queiroz, Giselle; Magnoli, Fábio Carlos; Portaro, Fernanda C. V.; Serrano, Solange M. T.; Lopes, Aline Soriano; Paes Leme, Adriana Franco; van den Berg, Carmen W.; Tambourgi, Denise V.

2013-01-01

Background Snake Venom Metalloproteinases (SVMPs) are amongst the key enzymes that contribute to the high toxicity of snake venom. We have recently shown that snake venoms from the Bothrops genus activate the Complement system (C) by promoting direct cleavage of C-components and generating anaphylatoxins, thereby contributing to the pathology and spread of the venom. The aim of the present study was to isolate and characterize the C-activating protease from Bothrops pirajai venom. Results Using two gel-filtration chromatography steps, a metalloproteinase of 23 kDa that activates Complement was isolated from Bothrops pirajai venom. The mass spectrometric identification of this protein, named here as C-SVMP, revealed peptides that matched sequences from the P-I class of SVMPs. C-SVMP activated the alternative, classical and lectin C-pathways by cleaving the α-chain of C3, C4 and C5, thereby generating anaphylatoxins C3a, C4a and C5a. In vivo, C-SVMP induced consumption of murine complement components, most likely by activation of the pathways and/or by direct cleavage of C3, leading to a reduction of serum lytic activity. Conclusion We show here that a P-I metalloproteinase from Bothrops pirajai snake venom activated the Complement system by direct cleavage of the central C-components, i.e., C3, C4 and C5, thereby generating biologically active fragments, such as anaphylatoxins, and by cleaving the C1-Inhibitor, which may affect Complement activation control. These results suggest that direct complement activation by SVMPs may play a role in the progression of symptoms that follow envenomation. PMID:24205428

Molluskan Hemocyanins Activate the Classical Pathway of the Human Complement System through Natural Antibodies.

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Pizarro-Bauerle, Javier; Maldonado, Ismael; Sosoniuk-Roche, Eduardo; Vallejos, Gerardo; López, Mercedes N; Salazar-Onfray, Flavio; Aguilar-Guzmán, Lorena; Valck, Carolina; Ferreira, Arturo; Becker, María Inés

2017-01-01

Molluskan hemocyanins are enormous oxygen-carrier glycoproteins that show remarkable immunostimulatory properties when inoculated in mammals, such as the generation of high levels of antibodies, a strong cellular reaction, and generation of non-specific antitumor immune responses in some types of cancer, particularly for superficial bladder cancer. These proteins have the ability to bias the immune response toward a T h 1 phenotype. However, despite all their current uses with beneficial clinical outcomes, a clear mechanism explaining these properties is not available. Taking into account reports of natural antibodies against the hemocyanin of the gastropod Megathura crenulata [keyhole limpet hemocyanin (KLH)] in humans as well as other vertebrate species, we report here for the first time, the presence, in sera from unimmunized healthy donors, of antibodies recognizing, in addition to KLH, two other hemocyanins from gastropods with documented immunomodulatory capacities: Fisurella latimarginata hemocyanin (FLH) and Concholepas concholepas hemocyanin (CCH). Through an ELISA screening, we found IgM and IgG antibodies reactive with these hemocyanins. When the capacity of these antibodies to bind deglycosylated hemocyanins was studied, no decreased interaction was detected. Moreover, in the case of FLH, deglycosylation increased antibody binding. We evaluated through an in vitro complement deposition assay whether these antibodies activated the classical pathway of the human complement system. The results showed that all three hemocyanins and their deglycosylated counterparts elicited this activation, mediated by C1 binding to immunoglobulins. Thus, this work contributes to the understanding on how the complement system could participate in the immunostimulatory properties of hemocyanins, through natural, complement-activating antibodies reacting with these proteins. Although a role for carbohydrates cannot be completely ruled out, in our experimental setting

Complement-Mediated Enhancement of Monocyte Adhesion to Endothelial Cells by HLA Antibodies, and Blockade by a Specific Inhibitor of the Classical Complement Cascade, TNT003

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Valenzuela, Nicole M.; Thomas, Kimberly A.; Mulder, Arend; Parry, Graham C.; Panicker, Sandip; Reed, Elaine F.

2017-01-01

Background Antibody-mediated rejection (AMR) of most solid organs is characterized by evidence of complement activation and/or intragraft macrophages (C4d + and CD68+ biopsies). We previously demonstrated that crosslinking of HLA I by antibodies triggered endothelial activation and monocyte adhesion. We hypothesized that activation of the classical complement pathway at the endothelial cell surface by HLA antibodies would enhance monocyte adhesion through soluble split product generation, in parallel with direct endothelial activation downstream of HLA signaling. Methods Primary human aortic endothelial cells (HAEC) were stimulated with HLA class I antibodies in the presence of intact human serum complement. C3a and C5a generation, endothelial P-selectin expression, and adhesion of human primary and immortalized monocytes (Mono Mac 6) were measured. Alternatively, HAEC or monocytes were directly stimulated with purified C3a or C5a. Classical complement activation was inhibited by pretreatment of complement with an anti-C1s antibody (TNT003). Results Treatment of HAEC with HLA antibody and human complement increased the formation of C3a and C5a. Monocyte recruitment by human HLA antibodies was enhanced in the presence of intact human serum complement or purified C3a or C5a. Specific inhibition of the classical complement pathway using TNT003 or C1q-depleted serum significantly reduced adhesion of monocytes in the presence of human complement. Conclusions Despite persistent endothelial viability in the presence of HLA antibodies and complement, upstream complement anaphylatoxin production exacerbates endothelial exocytosis and leukocyte recruitment. Upstream inhibition of classical complement may be therapeutic to dampen mononuclear cell recruitment and endothelial activation characteristic of microvascular inflammation during AMR. PMID:28640789

Immune response to snake envenoming and treatment with antivenom; complement activation, cytokine production and mast cell degranulation.

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Shelley F Stone

Full Text Available BACKGROUND: Snake bite is one of the most neglected public health issues in poor rural communities worldwide. In addition to the clinical effects of envenoming, treatment with antivenom frequently causes serious adverse reactions, including hypersensitivity reactions (including anaphylaxis and pyrogenic reactions. We aimed to investigate the immune responses to Sri Lankan snake envenoming (predominantly by Russell's viper and antivenom treatment. METHODOLOGY/PRINCIPAL FINDINGS: Plasma concentrations of Interleukin (IL-6, IL-10, tumor necrosis factor α (TNFα, soluble TNF receptor I (sTNFRI, anaphylatoxins (C3a, C4a, C5a; markers of complement activation, mast cell tryptase (MCT, and histamine were measured in 120 Sri Lankan snakebite victims, both before and after treatment with antivenom. Immune mediator concentrations were correlated with envenoming features and the severity of antivenom-induced reactions including anaphylaxis. Envenoming was associated with complement activation and increased cytokine concentrations prior to antivenom administration, which correlated with non-specific systemic symptoms of envenoming but not with coagulopathy or neurotoxicity. Typical hypersensitivity reactions to antivenom occurred in 77/120 patients (64%, satisfying criteria for a diagnosis of anaphylaxis in 57/120 (48%. Pyrogenic reactions were observed in 32/120 patients (27%. All patients had further elevations in cytokine concentrations, but not complement activation, after the administration of antivenom, whether a reaction was noted to occur or not. Patients with anaphylaxis had significantly elevated concentrations of MCT and histamine. CONCLUSIONS/SIGNIFICANCE: We have demonstrated that Sri Lankan snake envenoming is characterized by significant complement activation and release of inflammatory mediators. Antivenom treatment further enhances the release of inflammatory mediators in all patients, with anaphylactic reactions characterised by high

Methanol extract of grain dust shows complement fixing activity and other characteristics similar to tannic acid.

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Skea, D; Broder, I

1986-01-01

We have found several similarities between tannic acid and grain dust extract prepared with methanol. Both formed a precipitate with IgG, and these interactions were inhibited by albumin. In addition, both preparations fixed complement; this activity was heat stable and was removed by prior adsorption of the preparations with hide powder. Adsorption with polyvinyl polypyrrolidone reduced the complement-fixing activity of tannic acid but not that of the methanol grain dust extract. The similarities between tannic acid and the methanol grain dust extract are consistent with the presence of a tannin or tanninlike material in grain dust. Images FIGURE 1. PMID:3709479

Mesenchymal Stem Cells Control Complement C5 Activation by Factor H in Lupus Nephritis

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Haijun Ma

2018-06-01

Full Text Available Lupus nephritis (LN is one of the most severe complications of systemic lupus erythematosus (SLE caused by uncontrolled activation of the complement system. Mesenchymal stem cells (MSCs exhibit clinical efficacy for severe LN in our previous studies, but the underlying mechanisms of MSCs regulating complement activation remain largely unknown. Here we show that significantly elevated C5a and C5b-9 were found in patients with LN, which were notably correlated with proteinuria and different renal pathological indexes of LN. MSCs suppressed systemic and intrarenal activation of C5, increased the plasma levels of factor H (FH, and ameliorated renal disease in lupus mice. Importantly, MSCs transplantation up-regulated the decreased FH in patients with LN. Mechanistically, interferon-α enhanced the secretion of FH by MSCs. These data demonstrate that MSCs inhibit the activation of pathogenic C5 via up-regulation of FH, which improves our understanding of the immunomodulatory mechanisms of MSCs in the treatment of lupus nephritis. Keywords: Lupus nephritis, C5, MSCs, FH

Complement activation, endothelial dysfunction, insulin resistance and chronic heart failure

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Bjerre, M.; Kistorp, C.; Hansen, T.K.

2010-01-01

Objectives. Patients with chronic heart failure (CHF) have an exaggerated immune response, endothelial damage/dysfunction, and increased risk of diabetes mellitus (DM). The inter-relationship(s) between indices of complement activation (soluble membrane attack complex, sMAC), inflammation (hs...... to ischemic heart disease (IHD) as compared with CHF patients with non-ischemic ethiology (p = 0.02), but were not predictive of survival or progression of CHF. A moderate strong relation between sMAC and sEsel levels was found beta = 0.33 (p ... damaging of the heart tissue...

Complement in patients receiving maintenance hemodialysis: functional screening and quantitative analysis

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Horikoshi Satoshi

2010-12-01

Full Text Available Abstract Background The complement system is vital for innate immunity and is implicated in the pathogenesis of inflammatory diseases and the mechanism of host defense. Complement deficiencies occasionally cause life-threatening diseases. In hemodialysis (HD patients, profiles on complement functional activity and deficiency are still obscure. The objectives of the present study were to measure the functional complement activities of the classical pathway (CP, lectin pathway (LP and alternative pathway (AP using a novel method and consequently to elucidate the rates of deficiencies among HD patients. Methods In the present study, 244 HD patients at one dialysis center and 204 healthy controls were enrolled. Functional complement activities were measured simultaneously using the Wielisa®-kit. The combination of the results of these three pathway activities allows us to speculate which candidate complement is deficient; subsequently, the deficient complement was determined. Results All three functional complement activities were significantly higher in the HD patients than in the control group (P ®-kit, 16 sera (8.8% with mannose-binding lectin (MBL deficiency, 1 serum (0.4% with C4 deficiency, 1 serum (0.4% with C9 deficiency, and 1 serum (0.4% with B deficiency were observed in the HD group, and 18 sera (8.8% with MBL deficiency and 1 serum (0.5% with B deficiency were observed in the control group. There were no significant differences in the 5-year mortality rate between each complement-deficient group and the complement-sufficient group among the HD patients. Conclusion This is the first report that profiles complement deficiencies by simultaneous measurement of functional activities of the three complement pathways in HD patients. Hemodialysis patients frequently suffer from infections or malignancies, but functional complement deficiencies do not confer additional risk of mortality.

Controlling the complement system in inflammation.

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Kirschfink, M

1997-12-01

Inappropriate or excessive activation of the complement system can lead to harmful, potentially life-threatening consequences due to severe inflammatory tissue destruction. These consequences are clinically manifested in various disorders, including septic shock, multiple organ failure and hyperacute graft rejection. Genetic complement deficiencies or complement depletion have been proven to be beneficial in reducing tissue injury in a number of animal models of severe complement-dependent inflammation. It is therefore believed that therapeutic inhibition of complement is likely to arrest the process of certain diseases. Attempts to efficiently inhibit complement include the application of endogenous soluble complement inhibitors (C1-inhibitor, recombinant soluble complement receptor 1- rsCR1), the administration of antibodies, either blocking key proteins of the cascade reaction (e.g. C3, C5), neutralizing the action of the complement-derived anaphylatoxin C5a, or interfering with complement receptor 3 (CR3, CD18/11b)-mediated adhesion of inflammatory cells to the vascular endothelium. In addition, incorporation of membrane-bound complement regulators (DAF-CD55, MCP-CD46, CD59) has become possible by transfection of the correspondent cDNA into xenogeneic cells. Thereby, protection against complement-mediated inflammatory tissue damage could be achieved in various animal models of sepsis, myocardial as well as intestinal ischemia/reperfusion injury, adult respiratory distress syndrome, nephritis and graft rejection. Supported by results from first clinical trials, complement inhibition appears to be a suitable therapeutic approach to control inflammation. Current strategies to specifically inhibit complement in inflammation have been discussed at a recent meeting on the 'Immune Consequences of Trauma, Shock and Sepsis', held from March 4-8, 1997, in Munich, Germany. The Congress (chairman: E. Faist, Munich, Germany), which was held in close cooperation with various

Viral mimicry of the complement system

Indian Academy of Sciences (India)

The complement system is a potent innate immune mechanism consisting of cascades of proteins which are designed to fight against and annul intrusion of all the foreign pathogens. Although viruses are smaller in size and have relatively simple structure, they are not immune to complement attack. Thus, activation of the ...

Complement-mediated bactericidal activity of anti-factor H binding protein monoclonal antibodies against the meningococcus relies upon blocking factor H binding.

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Giuntini, Serena; Reason, Donald C; Granoff, Dan M

2011-09-01

Binding of the complement-downregulating protein factor H (fH) to the surface of the meningococcus is important for survival of the organism in human serum. The meningococcal vaccine candidate factor H binding protein (fHbp) is an important ligand for human fH. While some fHbp-specific monoclonal antibodies (MAbs) block binding of fH to fHbp, the stoichiometry of blocking in the presence of high serum concentrations of fH and its effect on complement-mediated bactericidal activity are unknown. To investigate this question, we constructed chimeric antibodies in which the human IgG1 constant region was paired with three murine fHbp-specific binding domains designated JAR 3, JAR 5, and MAb502. By surface plasmon resonance, the association rates for binding of all three MAbs to immobilized fHbp were >50-fold higher than that for binding of fH to fHbp, and the MAb dissociation rates were >500-fold lower than that for fH. While all three MAbs elicited similar C1q-dependent C4b deposition on live bacteria (classical complement pathway), only those antibodies that inhibited binding of fH to fHbp (JAR 3 and JAR 5) had bactericidal activity with human complement. MAb502, which did not inhibit fH binding, had complement-mediated bactericidal activity only when tested with fH-depleted human complement. When an IgG1 anti-fHbp MAb binds to sparsely exposed fHbp on the bacterial surface, there appears to be insufficient complement activation for bacteriolysis unless fH binding also is inhibited. The ability of fHbp vaccines to elicit protective antibodies, therefore, is likely to be enhanced if the antibody repertoire is of high avidity and includes fH-blocking activity.

Complement, a target for therapy in inflammatory and degenerative diseases.

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Morgan, B Paul; Harris, Claire L

2015-12-01

The complement system is a key innate immune defence against infection and an important driver of inflammation; however, these very properties can also cause harm. Inappropriate or uncontrolled activation of complement can cause local and/or systemic inflammation, tissue damage and disease. Complement provides numerous options for drug development as it is a proteolytic cascade that involves nine specific proteases, unique multimolecular activation and lytic complexes, an arsenal of natural inhibitors, and numerous receptors that bind to activation fragments. Drug design is facilitated by the increasingly detailed structural understanding of the molecules involved in the complement system. Only two anti-complement drugs are currently on the market, but many more are being developed for diseases that include infectious, inflammatory, degenerative, traumatic and neoplastic disorders. In this Review, we describe the history, current landscape and future directions for anti-complement therapies.

Complement Attack against Aspergillus and Corresponding Evasion Mechanisms

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Cornelia Speth

2012-01-01

Full Text Available Invasive aspergillosis shows a high mortality rate particularly in immunocompromised patients. Perpetually increasing numbers of affected patients highlight the importance of a clearer understanding of interactions between innate immunity and fungi. Innate immunity is considered to be the most significant host defence against invasive fungal infections. Complement represents a crucial part of this first line defence and comprises direct effects against invading pathogens as well as bridging functions to other parts of the immune network. However, despite the potency of complement to attack foreign pathogens, the prevalence of invasive fungal infections is increasing. Two possible reasons may explain that phenomenon: First, complement activation might be insufficient for an effective antifungal defence in risk patients (due to, e.g., low complement levels, poor recognition of fungal surface, or missing interplay with other immune elements in immunocompromised patients. On the other hand, fungi may have developed evasion strategies to avoid recognition and/or eradication by complement. In this review, we summarize the most important interactions between Aspergillus and the complement system. We describe the various ways of complement activation by Aspergillus and the antifungal effects of the system, and also show proven and probable mechanisms of Aspergillus for complement evasion.

Tsetse GmmSRPN10 has anti-complement activity and is important for successful establishment of trypanosome infections in the fly midgut.

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Cher-Pheng Ooi

2015-01-01

Full Text Available The complement cascade in mammalian blood can damage the alimentary tract of haematophagous arthropods. As such, these animals have evolved their own repertoire of complement-inactivating factors, which are inadvertently exploited by blood-borne pathogens to escape complement lysis. Unlike the bloodstream stages, the procyclic (insect stage of Trypanosoma brucei is highly susceptible to complement killing, which is puzzling considering that a tsetse takes a bloodmeal every 2-4 days. In this study, we identified four tsetse (Glossina morsitans morsitans serine protease inhibitors (serpins from a midgut expressed sequence tag (EST library (GmmSRPN3, GmmSRPN5, GmmSRPN9 and GmmSRPN10 and investigated their role in modulating the establishment of a T. brucei infection in the midgut. Although not having evolved in a common blood-feeding ancestor, all four serpins have an active site sharing remarkable homology with the human complement C1-inhibitor serpin, SerpinG1. RNAi knockdown of individual GmmSRPN9 and GmmSRPN10 genes resulted in a significant decreased rate of infection by procyclic form T. brucei. Furthermore, recombinant GmmSRPN10 was both able to inhibit the activity of human complement-cascade serine proteases, C1s and Factor D, and to protect the in vitro killing of procyclic trypanosomes when incubated with complement-activated human serum. Thus, the secretion of serpins, which may be part of a bloodmeal complement inactivation system in tsetse, is used by procyclic trypanosomes to evade an influx of fresh trypanolytic complement with each bloodmeal. This highlights another facet of the complicated relationship between T. brucei and its tsetse vector, where the parasite takes advantage of tsetse physiology to further its chances of propagation and transmission.

Tsetse GmmSRPN10 has anti-complement activity and is important for successful establishment of trypanosome infections in the fly midgut.

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Ooi, Cher-Pheng; Haines, Lee R; Southern, Daniel M; Lehane, Michael J; Acosta-Serrano, Alvaro

2015-01-01

The complement cascade in mammalian blood can damage the alimentary tract of haematophagous arthropods. As such, these animals have evolved their own repertoire of complement-inactivating factors, which are inadvertently exploited by blood-borne pathogens to escape complement lysis. Unlike the bloodstream stages, the procyclic (insect) stage of Trypanosoma brucei is highly susceptible to complement killing, which is puzzling considering that a tsetse takes a bloodmeal every 2-4 days. In this study, we identified four tsetse (Glossina morsitans morsitans) serine protease inhibitors (serpins) from a midgut expressed sequence tag (EST) library (GmmSRPN3, GmmSRPN5, GmmSRPN9 and GmmSRPN10) and investigated their role in modulating the establishment of a T. brucei infection in the midgut. Although not having evolved in a common blood-feeding ancestor, all four serpins have an active site sharing remarkable homology with the human complement C1-inhibitor serpin, SerpinG1. RNAi knockdown of individual GmmSRPN9 and GmmSRPN10 genes resulted in a significant decreased rate of infection by procyclic form T. brucei. Furthermore, recombinant GmmSRPN10 was both able to inhibit the activity of human complement-cascade serine proteases, C1s and Factor D, and to protect the in vitro killing of procyclic trypanosomes when incubated with complement-activated human serum. Thus, the secretion of serpins, which may be part of a bloodmeal complement inactivation system in tsetse, is used by procyclic trypanosomes to evade an influx of fresh trypanolytic complement with each bloodmeal. This highlights another facet of the complicated relationship between T. brucei and its tsetse vector, where the parasite takes advantage of tsetse physiology to further its chances of propagation and transmission.

Level of complement activity predicts cardiac dysfunction after acute myocardial infarction treated with primary percutaneous coronary intervention

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Haahr-Pedersen, Sune; Bjerre, Mette; Flyvbjerg, Allan

2009-01-01

BACKGROUND: The positive effect of reperfusion after ST-elevation myocardial infarction (STEMI) can be reduced by ischemic/reperfusion (I/R) injury.Mannose-binding-lectin (MBL) and soluble C5b-9 (membrane-attack-complex) are involved in complement-driven cell lysis and may play a role in human...... with increased risk of cardiac dysfunction in STEMI patients treated with pPCI, probably due to increased complement activity during the ischemic and reperfusion process. The predictive value of low peripheral plasma sC5b-9 may be explained by an accumulation and activation of sC5b-9 in the infarcted myocardium....

Disease-linked mutations in factor H reveal pivotal role of cofactor activity in self-surface-selective regulation of complement activation.

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Kerr, Heather; Wong, Edwin; Makou, Elisavet; Yang, Yi; Marchbank, Kevin; Kavanagh, David; Richards, Anna; Herbert, Andrew P; Barlow, Paul N

2017-08-11

Spontaneous activation enables the complement system to respond very rapidly to diverse threats. This activation is efficiently suppressed by complement factor H (CFH) on self-surfaces but not on foreign surfaces. The surface selectivity of CFH, a soluble protein containing 20 complement-control protein modules (CCPs 1-20), may be compromised by disease-linked mutations. However, which of the several functions of CFH drives this self-surface selectivity remains unknown. To address this, we expressed human CFH mutants in Pichia pastoris We found that recombinant I62-CFH (protective against age-related macular degeneration) and V62-CFH functioned equivalently, matching or outperforming plasma-derived CFH, whereas R53H-CFH, linked to atypical hemolytic uremic syndrome (aHUS), was defective in C3bBb decay-accelerating activity (DAA) and factor I cofactor activity (CA). The aHUS-linked CCP 19 mutant D1119G-CFH had virtually no CA on (self-like) sheep erythrocytes ( E S ) but retained DAA. The aHUS-linked CCP 20 mutant S1191L/V1197A-CFH (LA-CFH) had dramatically reduced CA on E S but was less compromised in DAA. D1119G-CFH and LA-CFH both performed poorly at preventing complement-mediated hemolysis of E S PspCN, a CFH-binding Streptococcus pneumoniae protein domain, binds CFH tightly and increases accessibility of CCPs 19 and 20. PspCN did not improve the DAA of any CFH variant on E S Conversely, PspCN boosted the CA, on E S , of I62-CFH, R53H-CFH, and LA-CFH and also enhanced hemolysis protection by I62-CFH and LA-CFH. We conclude that CCPs 19 and 20 are critical for efficient CA on self-surfaces but less important for DAA. Exposing CCPs 19 and 20 with PspCN and thus enhancing CA on self-surfaces may reverse deficiencies of some CFH variants. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Potential of Murine IgG1 and Human IgG4 to Inhibit the Classical Complement and Fcγ Receptor Activation Pathways

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Gina-Maria Lilienthal

2018-05-01

Full Text Available IgG antibodies (Abs mediate their effector functions through the interaction with Fcγ receptors (FcγRs and the complement factors. The main IgG-mediated complement activation pathway is induced through the binding of complement C1q to IgG Abs. This interaction is dependent on antigen-dependent hexamer formation of human IgG1 and IgG3 to increase the affinity for the six-headed C1q molecule. By contrast, human IgG4 fails to bind to C1q. Instead, it has been suggested that human IgG4 can block IgG1 and IgG3 hexamerization required for their binding to C1q and activating the complement. Here, we show that murine IgG1, which functionally resembles human IgG4 by not interacting with C1q, inhibits the binding of IgG2a, IgG2b, and IgG3 to C1q in vitro, and suppresses IgG2a-mediated complement activation in a hemolytic assay in an antigen-dependent and IgG subclass-specific manner. From this perspective, we discuss the potential of murine IgG1 and human IgG4 to block the complement activation as well as suppressive effects of sialylated IgG subclass Abs on FcγR-mediated immune cell activation. Accumulating evidence suggests that both mechanisms seem to be responsible for preventing uncontrolled IgG (autoAb-induced inflammation in mice and humans. Distinct IgG subclass distributions and functionally opposite IgG Fc glycosylation patterns might explain different outcomes of IgG-mediated immune responses and provide new therapeutic options through the induction, enrichment, or application of antigen-specific sialylated human IgG4 to prevent complement and FcγR activation as well.

Complement Activation Induces Neutrophil Adhesion and Neutrophil-Platelet Aggregate Formation on Vascular Endothelial Cells

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Magdalena Riedl

2017-01-01

Discussion: Therefore, our findings of (i neutrophils adhering to complement-activated endothelial cells, (ii the formation of neutrophil-platelet aggregates on endothelial cells, and (iii the ability of aHUS serum to induce similar effects identify a possible role for neutrophils in aHUS manifestation.

The Complement System: A Prey of Trypanosoma cruzi

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Kárita C. F. Lidani

2017-04-01

Full Text Available Trypanosoma cruzi is a protozoan parasite known to cause Chagas disease (CD, a neglected sickness that affects around 6–8 million people worldwide. Originally, CD was mainly found in Latin America but more recently, it has been spread to countries in North America, Asia, and Europe due the international migration from endemic areas. Thus, at present CD represents an important concern of global public health. Most of individuals that are infected by T. cruzi may remain in asymptomatic form all lifelong, but up to 40% of them will develop cardiomyopathy, digestive mega syndromes, or both. The interaction between the T. cruzi infective forms and host-related immune factors represents a key point for a better understanding of the physiopathology of CD. In this context, the complement, as one of the first line of host defense against infection was shown to play an important role in recognizing T. cruzi metacyclic trypomastigotes and in controlling parasite invasion. The complement consists of at least 35 or more plasma proteins and cell surface receptors/regulators, which can be activated by three pathways: classical (CP, lectin (LP, and alternative (AP. The CP and LP are mainly initiated by immune complexes or pathogen-associated molecular patterns (PAMPs, respectively, whereas AP is spontaneously activated by hydrolysis of C3. Once activated, several relevant complement functions are generated which include opsonization and phagocytosis of particles or microorganisms and cell lysis. An important step during T. cruzi infection is when intracellular trypomastigotes are release to bloodstream where they may be target by complement. Nevertheless, the parasite uses a sequence of events in order to escape from complement-mediated lysis. In fact, several T. cruzi molecules are known to interfere in the initiation of all three pathways and in the assembly of C3 convertase, a key step in the activation of complement. Moreover, T. cruzi promotes secretion

Early decrease in total hemolytic complement activity (CH100) after fasting or intestinal bypass in the rat.

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Montanari, M; Violi, V; Muri, M; Roncoroni, L; Mora, G; Ronzoni, M

1986-01-01

An evaluation of total hemolytic complement activity (CH100) after fasting or intestinal bypass was performed in rats. The experiment lasted 6 days. Three groups, of 5 animals each, were studied. On the 1st day, basal values of total complement (TC), albumin and body weight were determined. Group A received normal, ad libitum feeding, group B started on a 'water only' diet, group C underwent intestinal bypass. On the 4th and 6th day the parameters were assessed. TC mean values were significantly lower in groups B and C, as compared to group A, on the 4th as well as on the 6th day (p less than 0.01 by Mann-Whitney's U test). Body weight showed a similar trend. Differences in albumin were never statistically significant. Limitations of the analytical method are discussed. The data show that fasting or bypass-induced malabsorption may determine an early decrease in total hemolytic complement activity, though a development of an immune deficiency is not proved.

Complement elevation in spinal cord injury.

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Rebhun, J; Botvin, J

1980-05-01

Laboratory studies revealed an elevated complement in 66% of patients with spinal cord injury. It is postulated that the activated complement may be a component of self-feeding immunological mechanism responsible for the failure of regeneration of a mature mammalian spinal cord. There was no evidence that such an injury had any effect on pre-existing atopy.

Novel Evasion Mechanisms of the Classical Complement Pathway.

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Garcia, Brandon L; Zwarthoff, Seline A; Rooijakkers, Suzan H M; Geisbrecht, Brian V

2016-09-15

Complement is a network of soluble and cell surface-associated proteins that gives rise to a self-amplifying, yet tightly regulated system with fundamental roles in immune surveillance and clearance. Complement becomes activated on the surface of nonself cells by one of three initiating mechanisms known as the classical, lectin, and alternative pathways. Evasion of complement function is a hallmark of invasive pathogens and hematophagous organisms. Although many complement-inhibition strategies hinge on hijacking activities of endogenous complement regulatory proteins, an increasing number of uniquely evolved evasion molecules have been discovered over the past decade. In this review, we focus on several recent investigations that revealed mechanistically distinct inhibitors of the classical pathway. Because the classical pathway is an important and specific mediator of various autoimmune and inflammatory disorders, in-depth knowledge of novel evasion mechanisms could direct future development of therapeutic anti-inflammatory molecules. Copyright © 2016 by The American Association of Immunologists, Inc.

Francisella tularensis Confronts the Complement System

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Susan R. Brock

2017-12-01

Full Text Available Francisella tularensis has developed a number of effective evasion strategies to counteract host immune defenses, not the least of which is its ability to interact with the complement system to its own advantage. Following exposure of the bacterium to fresh human serum, complement is activated and C3b and iC3b can be found covalently attached to the bacterial surface. However, the lipopolysaccharide and capsule of the F. tularensis cell wall prevent complement-mediated lysis and endow the bacterium with serum resistance. Opsonization of F. tularensis with C3 greatly increases its uptake by human neutrophils, dendritic cells and macrophages. Uptake occurs by an unusual looping morphology in human macrophages. Complement receptor 3 is thought to play an important role in opsonophagocytosis by human macrophages, and signaling through this receptor can antagonize Toll-like receptor 2-initiated macrophage activation. Complement C3 also determines the survival of infected human macrophages and perhaps other cell types. C3-opsonization of F. tularensis subsp. tularensis strain SCHU S4 results in greatly increased death of infected human macrophages, which requires more than complement receptor engagement and is independent of the intracellular replication by the pathogen. Given its entry into the cytosol of host cells, F. tularensis has the potential for a number of other complement-mediated interactions. Studies on the uptake C3-opsonized adenovirus have suggested the existence of a C3 sensing system that initiates cellular responses to cytosolic C3b present on invading microbes. Here we propose that C3 peptides enter the cytosol of human macrophages following phagosome escape of F. tularensis and are recognized as intruding molecular patterns that signal host cell death. With the discovery of new roles for intracellular C3, a better understanding of tularemia pathogenesis is likely to emerge.

Global Autorecognition and Activation of Complement by Mannan-Binding Lectin in a Mouse Model of Type 1 Diabetes

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Esben Axelgaard

2017-01-01

Full Text Available Increasing evidence links mannan-binding lectin (MBL to late vascular complications of diabetes. MBL is a complement-activating pattern recognition molecule of the innate immune system that can mediate an inflammation response through activation of the lectin pathway. In two recent animal studies, we have shown that autoreactivity of MBL is increased in the kidney in diabetic nephropathy. We hypothesize that long-term exposure to uncontrolled high blood glucose in diabetes may mediate formation of neoepitopes in several tissues and that MBL is able to recognize these structures and thus activate the lectin pathway. To test this hypothesis, we induced diabetes by injection of low-dose streptozotocin in MBL double-knockout (MBL/DKO mice. Development of diabetes was followed by measurements of blood glucose and urine albumin-to-creatinine ratio. Fluorophore-labelled recombinant MBL was injected intravenously in diabetic and nondiabetic mice followed by ex vivo imaging of several organs. We observed that MBL accumulated in the heart, liver, brain, lung, pancreas, and intestines of diabetic mice. We furthermore detected increased systemic complement activation after administration of MBL, thus indicating MBL-mediated systemic complement activation in these animals. These new findings indicate a global role of MBL during late diabetes-mediated vascular complications in various tissues.

Combined roles of human IgG subclass, alternative complement pathway activation, and epitope density in the bactericidal activity of antibodies to meningococcal factor h binding protein.

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Giuntini, Serena; Reason, Donald C; Granoff, Dan M

2012-01-01

Meningococcal vaccines containing factor H binding protein (fHbp) are in clinical development. fHbp binds human fH, which enables the meningococcus to resist complement-mediated bacteriolysis. Previously, we found that chimeric human IgG1 mouse anti-fHbp monoclonal antibodies (MAbs) had human complement-mediated bactericidal activity only if the MAb inhibited fH binding. Since IgG subclasses differ in their ability to activate complement, we investigated the role of human IgG subclasses on antibody functional activity. We constructed chimeric MAbs in which three different murine fHbp-specific binding domains were each paired with human IgG1, IgG2, or IgG3. Against a wild-type group B isolate, all three IgG3 MAbs, irrespective of their ability to inhibit fH binding, had bactericidal activity that was >5-fold higher than the respective IgG1 MAbs, while the IgG2 MAbs had the least activity. Against a mutant with increased fHbp expression, the anti-fHbp MAbs elicited greater C4b deposition (classical pathway) and greater bactericidal activity than against the wild-type strain, and the IgG1 MAbs had similar or greater activity than the respective IgG3 MAbs. The bactericidal activity against both wild-type and mutant strains also was dependent, in part, on activation of the alternative complement pathway. Thus, at lower epitope density in the wild-type strain, the IgG3 anti-fHbp MAbs had the greatest bactericidal activity. At a higher epitope density in the mutant, the IgG1 MAbs had similar or greater bactericidal activity than the IgG3 MAbs, and the activity was less dependent on the inhibition of fH binding than at a lower epitope density.

A novel method for direct measurement of complement convertases activity in human serum

NARCIS (Netherlands)

Blom, A.M.; Volokhina, E.B.; Fransson, V.; Stromberg, P.; Berghard, L.; Viktorelius, M.; Mollnes, T.E.; Lopez-Trascasa, M.; Heuvel, B. van den; Goodship, T.H.; Marchbank, K.J.; Okroj, M.

2014-01-01

Complement convertases are enzymatic complexes that play a central role in sustaining and amplification of the complement cascade. Impairment of complement function leads directly or indirectly to pathological conditions, including higher infection rate, kidney diseases, autoimmune- or

Interpain A, a cysteine proteinase from Prevotella intermedia, inhibits complement by degrading complement factor C3.

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Michal Potempa

2009-02-01

Full Text Available Periodontitis is an inflammatory disease of the supporting structures of the teeth caused by, among other pathogens, Prevotella intermedia. Many strains of P. intermedia are resistant to killing by the human complement system, which is present at up to 70% of serum concentration in gingival crevicular fluid. Incubation of human serum with recombinant cysteine protease of P. intermedia (interpain A resulted in a drastic decrease in bactericidal activity of the serum. Furthermore, a clinical strain 59 expressing interpain A was more serum-resistant than another clinical strain 57, which did not express interpain A, as determined by Western blotting. Moreover, in the presence of the cysteine protease inhibitor E64, the killing of strain 59 by human serum was enhanced. Importantly, we found that the majority of P. intermedia strains isolated from chronic and aggressive periodontitis carry and express the interpain A gene. The protective effect of interpain A against serum bactericidal activity was found to be attributable to its ability to inhibit all three complement pathways through the efficient degradation of the alpha-chain of C3 -- the major complement factor common to all three pathways. P. intermedia has been known to co-aggregate with P. gingivalis, which produce gingipains to efficiently degrade complement factors. Here, interpain A was found to have a synergistic effect with gingipains on complement degradation. In addition, interpain A was able to activate the C1 complex in serum, causing deposition of C1q on inert and bacterial surfaces, which may be important at initial stages of infection when local inflammatory reaction may be beneficial for a pathogen. Taken together, the newly characterized interpain A proteinase appears to be an important virulence factor of P. intermedia.

Guilty as charged: all available evidence implicates complement's role in fetal demise.

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Girardi, Guillermina

2008-03-01

Appropriate complement inhibition is an absolute requirement for normal pregancy. Uncontrolled complement activation in the maternal-fetal interface leads to fetal death. Here we show that complement activation is a crucial and early mediator of pregnancy loss in two different mouse models of pregnancy loss. Using a mouse model of fetal loss and growth restriction (IUGR) induced by antiphospholipid antibodies (aPL), we examined the role of complement activation in fetal loss and IUGR. We found that C5a-C5aR interaction and neutrophils are key mediators of fetal injury. Treatment with heparin, the standard therapy for pregnant patients with aPL, prevents complement activation and protects mice from pregnancy complications induced by aPL, and anticoagulants that do not inhibit complement do not protect pregnancies. In an antibody-independent mouse model of spontaneous miscarriage and IUGR (CBA/JxDBA/2) we also identified C5a as an essential mediator. Complement activation caused dysregulation of the angiogenic factors required for normal placental development. In CBA/JxDBA/2 mice, we observed inflammatory infiltrates in placentas, functional deficiency of free vascular endothelial growth factor (VEGF), elevated levels of soluble VEGF receptor-1 (sVEGFR-1, also known as sFlt-1; a potent anti-angiogenic molecule), and defective placental development. Inhibition of complement activation blocked the increase in sVEGFR-1 and rescued pregnancies. Our studies in antibody-dependent and antibody-independent models of pregnancy complications identified complement activation as the key mediator of damage and will allow development of new interventions to prevent pregnancy loss and IUGR.

Complement evasion by Bordetella pertussis: implications for improving current vaccines.

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Jongerius, Ilse; Schuijt, Tim J; Mooi, Frits R; Pinelli, Elena

2015-04-01

Bordetella pertussis causes whooping cough or pertussis, a highly contagious disease of the respiratory tract. Despite high vaccination coverage, reported cases of pertussis are rising worldwide and it has become clear that the current vaccines must be improved. In addition to the well-known protective role of antibodies and T cells during B. pertussis infection, innate immune responses such as the complement system play an essential role in B. pertussis killing. In order to evade this complement activation and colonize the human host, B. pertussis expresses several molecules that inhibit complement activation. Interestingly, one of the known complement evasion proteins, autotransporter Vag8, is highly expressed in the recently emerged B. pertussis isolates. Here, we describe the current knowledge on how B. pertussis evades complement-mediated killing. In addition, we compare this to complement evasion strategies used by other bacterial species. Finally, we discuss the consequences of complement evasion by B. pertussis on adaptive immunity and how identification of the bacterial molecules and the mechanisms involved in complement evasion might help improve pertussis vaccines.

The complement inhibitor eculizumab in paroxysmal nocturnal hemoglobinuria.

NARCIS (Netherlands)

Hillmen, P.; Young, N.S.; Schubert, J.; Brodsky, R.A.; Socie, G.; Muus, P.; Roth, A.; Szer, J.; Elebute, M.O.; Nakamura, R.; Browne, P.; Risitano, A.M.; Hill, A.; Schrezenmeier, H.; Fu, C.L.; Maciejewski, J; Rollins, S.A.; Mojcik, C.F.; Rother, R.P.; Luzzatto, L.

2006-01-01

BACKGROUND: We tested the safety and efficacy of eculizumab, a humanized monoclonal antibody against terminal complement protein C5 that inhibits terminal complement activation, in patients with paroxysmal nocturnal hemoglobinuria (PNH). METHODS: We conducted a double-blind, randomized,

Specific, sensitive, precise, and rapid functional chromogenic assay of activated first complement component (C1) in plasma

DEFF Research Database (Denmark)

Munkvad, S; Jespersen, J; Sidelmann, Johannes Jakobsen

1990-01-01

We present a new functional assay for the first complement component (C1) in plasma, based on its activation by inhibition of the C1-esterase inhibitor (C1-inh) when monospecific antiserum to C1-inh is added to the plasma. After maximal activation, we can determine the concentration of activated ...

Storage of the complement components C4, C3, and C 3-activator in the human liver as PAS-negative globular hyaline bodies.

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Storch, W; Riedel, H; Trautmann, B; Justus, J; Hiemann, D

1982-01-01

Liver biopsies of a 58-year-old clinically healthy patient with a hepatomegaly and intracisternal PAS-negative globular hyaline bodies were immunofluorescent-optically examined for the content of the complement components C 1 q, C 4, C 9, C 1-inactivator, C 3-activator. Further examinations were performed for fibrinogen, IgG, IgA, IgM, IgD, IgE, L-chain (type chi and lambda), alpha 1-antitrypsin, alpha 1-fetoprotein, alpha 1- and alpha 2-glycoprotein, cholinesterase, ceruloplasmin, myoglobin, hemopexin, HBsAg and HBsAg. Th inclusion bodies reacted with antisera against the complement components C 4, C 3 and C 3-activator, as also identified by double immunofluorescence. Probably this is a disturbance of the protein metabolism of the liver cell with abnormal complement storage in the presence of normal total complement and normal complement components in the serum.

Multiple activities of LigB potentiate virulence of Leptospira interrogans: inhibition of alternative and classical pathways of complement.

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Henry A Choy

Full Text Available Microbial pathogens acquire the immediate imperative to avoid or counteract the formidable defense of innate immunity as soon as they overcome the initial physical barriers of the host. Many have adopted the strategy of directly disrupting the complement system through the capture of its components, using proteins on the pathogen's surface. In leptospirosis, pathogenic Leptospira spp. are resistant to complement-mediated killing, in contrast to the highly vulnerable non-pathogenic strains. Pathogenic L. interrogans uses LenA/LfhA and LcpA to respectively sequester and commandeer the function of two regulators, factor H and C4BP, which in turn bind C3b or C4b to interrupt the alternative or classical pathways of complement activation. LigB, another surface-proximal protein originally characterized as an adhesin binding multiple host proteins, has other activities suggesting its importance early in infection, including binding extracellular matrix, plasma, and cutaneous repair proteins and inhibiting hemostasis. In this study, we used a recent model of ectopic expression of LigB in the saprophyte, L. biflexa, to test the hypothesis that LigB also interacts with complement proteins C3b and C4b to promote the virulence of L. interrogans. The surface expression of LigB partially rescued the non-pathogen from killing by 5% normal human serum, showing 1.3- to 48-fold greater survival 4 to 6 d following exposure to complement than cultures of the non-expressing parental strain. Recombinant LigB7'-12 comprising the LigB-specific immunoglobulin repeats binds directly to human complement proteins, C3b and C4b, with respective K(ds of 43±26 nM and 69±18 nM. Repeats 9 to 11, previously shown to contain the binding domain for fibronectin and fibrinogen, are also important in LigB-complement interactions, which interfere with the alternative and classical pathways measured by complement-mediated hemolysis of erythrocytes. Thus, LigB is an adaptable interface

(IgA, IgG and IgM) levels and complement fixation activity in HIV

African Journals Online (AJOL)

The study was designed to evaluate the immunoglobulin A, G and M levels and complement fixation activity in HIV infected participants, who were not administered antiretroviral therapy (ART). Eighty (80) HIV infected participants, aged between 15 – 55 years (38 ±10 years), were recruited for the study. Forty five (45) of the ...

Complement and alcoholic liver disease: role of C1q in the pathogenesis of ethanol-induced liver injury in mice.

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Cohen, Jessica I; Roychowdhury, Sanjoy; McMullen, Megan R; Stavitsky, Abram B; Nagy, Laura E

2010-08-01

Complement is involved in the development of alcoholic liver disease in mice; however, the mechanisms for complement activation during ethanol exposure have not been identified. C1q, the recognition subunit of the first complement component, binds to apoptotic cells, thereby activating the classical complement pathway. Because ethanol exposure increases hepatocellular apoptosis, we hypothesized that ethanol-induced apoptosis would lead to activation of complement via the classical pathway. Wild-type and C1qa-/- mice were allowed free access to ethanol-containing diets or pair-fed control diets for 4 or 25 days. Ethanol feeding for 4 days increased apoptosis of Kupffer cells in both wild-type and C1qa-/- mice. Ethanol-induced deposition of C1q and C3b/iC3b/C3c was colocalized with apoptotic Kupffer cells in wild-type, but not C1qa-/-, mice. Furthermore, ethanol-induced increases in tumor necrosis factor-alpha and interleukin-6 expression at this early time point were suppressed in C1q-deficient mice. Chronic ethanol feeding (25 days) increased steatosis, hepatocyte apoptosis, and activity of serum alanine and aspartate aminotransferases in wild-type mice. These markers of hepatocyte injury were attenuated in C1qa-/- mice. In contrast, chronic ethanol (25 days)-induced increases in cytochrome P450 2E1 expression and oxidative stress did not differ between wild-type and C1qa-/- mice. For the first time, these data indicate that ethanol activates the classical complement pathway via C1q binding to apoptotic cells in the liver and that C1q contributes to the pathogenesis of ethanol-induced liver injury. Copyright (c) 2010 AGA Institute. Published by Elsevier Inc. All rights reserved.

Anti-complement activity in the saliva of phlebotomine sand flies and other haematophagous insects.

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Cavalcante, R R; Pereira, M H; Gontijo, N F

2003-07-01

The saliva of haematophagous insects has a series of pharmacological activities which may favour blood feeding. In the present study, an inhibitory effect on the complement system was observed in salivary extracts obtained from the phlebotomine sand flies Lutzomyia longipalpis and Lu. migonei. Saliva from Lu. longipalpis was capable of inhibiting both the classical and alternative pathways, while that from Lu. migonei acted only on the former. Other haematophagous insect species were screened for inhibition of the classical pathway. The triatomine bugs Panstrongylus megistus, Triatoma brasiliensis and Rhodnius prolixus were also able to inhibit the classical pathway whereas the mosquito Aedes aegyti and flea Ctenocephalides felis were not. The activity of Lu. longipalpis saliva on the classical pathway was partially characterized. The inhibitor is a protein of Mr 10000-30000 Da, which is very resistant to denaturation by heat. The inhibition of the complement system by phlebotomine sand flies may have a role in the transmission of Leishmania to the vertebrate hosts. The inhibitor molecule is thus a promising component of a vaccine to target salivary immunomodulators.

A potent complement factor C3 specific nanobody inhibiting multiple functions in the alternative pathway of human and murine complement.

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Jensen, Rasmus K; Pihl, Rasmus; Gadeberg, Trine A F; Jensen, Jan K; Andersen, Kasper R; Thiel, Steffen; Laursen, Nick S; Andersen, Gregers Rom

2018-03-01

The complement system is a complex, carefully regulated proteolytic cascade for which suppression of aberrant activation is of increasing clinical relevance and inhibition of the complement alternative pathway is a subject of intense research. Here, we describe the nanobody hC3Nb1 that binds to multiple functional states of C3 with sub-nanomolar affinity. The nanobody causes a complete shutdown of alternative pathway activity in human and murine serum when present in concentrations comparable to C3, and hC3Nb1 is shown to prevent both proconvertase assembly as well as binding of the C3 substrate to C3 convertases. Our crystal structure of the C3b-hC3Nb1 complex and functional experiments demonstrate that proconvertase formation is blocked by steric hindrance between the nanobody and an Asn-linked glycan on complement factor B. In addition, hC3Nb1 is shown to prevent factor H binding to C3b rationalizing its inhibition of factor I activity. Our results identify hC3Nb1 as a versatile, inexpensive, and powerful inhibitor of the alternative pathway in both human and murine in vitro model systems of complement activation. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

Evasion Mechanisms Used by Pathogens to Escape the Lectin Complement Pathway

DEFF Research Database (Denmark)

Rosbjerg, Anne; Genster, Ninette; Pilely, Katrine

2017-01-01

The complement system is a crucial defensive network that protects the host against invading pathogens. It is part of the innate immune system and can be initiated via three pathways: the lectin, classical and alternative activation pathway. Overall the network compiles a group of recognition...... the level of activity. The result is a pro-inflammatory response meant to combat foreign microbes. Microbial elimination is, however, not a straight forward procedure; pathogens have adapted to their environment by evolving a collection of evasion mechanisms that circumvent the human complement system....... Complement evasion strategies features different ways of exploiting human complement proteins and moreover features different pathogen-derived proteins that interfere with the normal processes. Accumulated, these mechanisms target all three complement activation pathways as well as the final common part...

Correlation of systemic lupus erythematosus disease activity with classical complement (CH50 function and related protein levels

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Salesi M

2008-09-01

Full Text Available "nBackground: The components of the classical complement pathway play an important role in the pathogenesis of systemic lupus erythematosus (SLE and are reportedly useful biomarkers of disease activity. In this study, we evaluate disease activity, complement function (total hemolytic complement, CH50 and complement protein levels (C3, C4, C3d, C4d, SC5b-9, comparing the results of patients with active disease versus those with inactive disease."n"nMethods: This cross-sectional study included 78 hospitalized women with SLE, 24 of whom were in the active group, with SLE disease activity indexes (SLEDAI.2K of >6, and 54 in the inactive group, with SLEDAI.2K of ≤6. Serum CH50 was measured using a red blood cell hemolytic assay. C3 and C4 levels were determined by nephlometry and plasma levels of C3d, C4d, SC5b-9 by ELISA. The data were statistically analyzed using SPSS."n"nResults: The mean (±standard error C4d levels of the inactive group were significantly higher than those of the active group (23.39±1.1µg/ml and 16.9±1.6µg/ml, respectively; p=0.003. There was also a significant correlation between C3 and C4 levels (p=0.807. The mean values of the other proteins (C3, C4, CH50, SC5b-9, and C3d circulating immune complex concentrations were not significantly different between the inactive group vs. the active group: 89.35±6.8 vs. 85.54±7.6mg/dl, 18.33±2.3 vs. 20.45±2.4mg/dl, 149.03±4.3 vs. 157±4.3U, 1414.4±114.94 vs. 1471.1±216.9ng/ml, 9.43±0.96 vs. 13.31±3.16µgEq/ml, respectively (p>0.05."n"nConclusions: According to our results, C4d levels may be used as a biomarker of disease activity. The significant correlation between C3 and C4 may confirm the activity of the classical pathway in SLE patients."n"nKeywords: Systemic lupus erythematosus, CH50, C3, C4, C3d, C4d, SC5b-9, inactive, flare.

Specificity of EIA immunoassay for complement factor Bb testing.

Science.gov (United States)

Pavlov, Igor Y; De Forest, Nikol; Delgado, Julio C

2011-01-01

During the alternative complement pathway activation, factor B is cleaved in two fragments, Ba and Bb. Concentration of those fragments is about 2 logs lower than of factor B present in the blood, which makes fragment detection challenging because of potential cross-reactivity. Lack of information on Bb assay cross-reactivity stimulated the authors to investigate this issue. We ran 109 healthy donor EDTA plasmas and 80 sera samples with both factor B immunodiffusion (The Binding Site) and Quidel Bb EIA assays. During the study it was shown that physiological concentrations of gently purified factor B demonstrated approximately 0.15% cross-reactivity in the Quidel Bb EIA assay. We also observed that Bb concentration in serum is higher than in plasma due to complement activation during clot formation which let us use sera as samples representing complement activated state. Our study demonstrated that despite the potential 0.15% cross-reactivity between endogenous factor B and cleaved Bb molecule, measuring plasma concentrations of factor Bb is adequate to evaluate the activation of the alternative complement pathway.

Complement System Part II: Role in Immunity

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Merle, Nicolas S.; Noe, Remi; Halbwachs-Mecarelli, Lise; Fremeaux-Bacchi, Veronique; Roumenina, Lubka T.

2015-01-01

The complement system has been considered for a long time as a simple lytic cascade, aimed to kill bacteria infecting the host organism. Nowadays, this vision has changed and it is well accepted that complement is a complex innate immune surveillance system, playing a key role in host homeostasis, inflammation, and in the defense against pathogens. This review discusses recent advances in the understanding of the role of complement in physiology and pathology. It starts with a description of complement contribution to the normal physiology (homeostasis) of a healthy organism, including the silent clearance of apoptotic cells and maintenance of cell survival. In pathology, complement can be a friend or a foe. It acts as a friend in the defense against pathogens, by inducing opsonization and a direct killing by C5b–9 membrane attack complex and by triggering inflammatory responses with the anaphylatoxins C3a and C5a. Opsonization plays also a major role in the mounting of an adaptive immune response, involving antigen presenting cells, T-, and B-lymphocytes. Nevertheless, it can be also an enemy, when pathogens hijack complement regulators to protect themselves from the immune system. Inadequate complement activation becomes a disease cause, as in atypical hemolytic uremic syndrome, C3 glomerulopathies, and systemic lupus erythematosus. Age-related macular degeneration and cancer will be described as examples showing that complement contributes to a large variety of conditions, far exceeding the classical examples of diseases associated with complement deficiencies. Finally, we discuss complement as a therapeutic target. PMID:26074922

A vital role for complement in heart disease

DEFF Research Database (Denmark)

Lappegård, Knut T; Garred, Peter; Jonasson, Lena

2014-01-01

fibrillation often share risk factors both with coronary heart disease and heart failure, and there is some evidence implicating complement activation in atrial fibrillation. Moreover, Chagas heart disease, a protozoal infection, is an important cause of heart failure in Latin America, and the complement...

Ficolin-3-mediated lectin complement pathway activation in patients with subarachnoid hemorrhage

DEFF Research Database (Denmark)

Zanier, Elisa R; Zangari, Rosalia; Munthe-Fog, Lea

2014-01-01

OBJECTIVES: To assess the involvement of ficolin-3, the main initiator of the lectin complement pathway (LCP), in subarachnoid hemorrhage (SAH) pathology and outcome. METHODS: In this preliminary exploratory study, plasma concentration of ficolin-3 and of ficolin-3-mediated functional LCP activity...... the World Federation of Neurosurgical Societies grading scale; vasospasm, defined as neuro-worsening with angiographic confirmation of vessel narrowing; cerebral ischemia, defined as hypodense lesion on CT scan performed before discharge; and 6-month outcome, assessed using the Glasgow Outcome Scale....... RESULTS: In patients, no changes were detected for ficolin-3 compared with controls. Notably, however, ficolin-3-mediated functional LCP activity was reduced. Low levels of plasma ficolin-3 and ficolin-3-mediated functional LCP activity were related to SAH severity, vasospasm, and cerebral ischemia...

Calcineurin inhibitor-induced complement system activation via ERK1/2 signalling is inhibited by SOCS-3 in human renal tubule cells.

Science.gov (United States)

Loeschenberger, Beatrix; Niess, Lea; Würzner, Reinhard; Schwelberger, Hubert; Eder, Iris E; Puhr, Martin; Guenther, Julia; Troppmair, Jakob; Rudnicki, Michael; Neuwirt, Hannes

2018-02-01

One factor that significantly contributes to renal allograft loss is chronic calcineurin inhibitor (CNI) nephrotoxicity (CIN). Among other factors, the complement (C-) system has been proposed to be involved CIN development. Hence, we investigated the impact of CNIs on intracellular signalling and the effects on the C-system in human renal tubule cells. In a qPCR array, CNI treatment upregulated C-factors and downregulated SOCS-3 and the complement inhibitors CD46 and CD55. Additionally, ERK1/-2 was required for these regulations. Following knock-down and overexpression of SOCS-3, we found that SOCS-3 inhibits ERK1/-2 signalling. Finally, we assessed terminal complement complex formation, cell viability and apoptosis. Terminal complement complex formation was induced by CNIs. Cell viability was significantly decreased, whereas apoptosis was increased. Both effects were reversed under complement component-depleted conditions. In vivo, increased ERK1/-2 phosphorylation and SOCS-3 downregulation were observed at the time of transplantation in renal allograft patients who developed a progressive decline of renal function in the follow-up compared to stable patients. The progressive cohort also had lower total C3 levels, suggesting higher complement activity at baseline. In conclusion, our data suggest that SOCS-3 inhibits CNI-induced ERK1/-2 signalling, thereby blunting the negative control of C-system activation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zonulin as prehaptoglobin2 regulates lung permeability and activates the complement system

OpenAIRE

Rittirsch, Daniel; Flierl, Michael A.; Nadeau, Brian A.; Day, Danielle E.; Huber-Lang, Markus S.; Grailer, Jamison J.; Zetoune, Firas S.; Andjelkovic, Anuska V.; Fasano, Alessio; Ward, Peter A.

2013-01-01

Zonulin is a protein involved in the regulation of tight junctions (TJ) in epithelial or endothelial cells. Zonulin is known to affect TJ in gut epithelial cells, but little is known about its influences in other organs. Prehaptoglobin2 has been identified as zonulin and is related to serine proteases (MASPs, C1qrs) that activate the complement system. The current study focused on the role of zonulin in development of acute lung injury (ALI) in C57BL/6 male mice following intrapulmonary depos...

Surviving mousepox infection requires the complement system.

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Elizabeth A Moulton

2008-12-01

Full Text Available Poxviruses subvert the host immune response by producing immunomodulatory proteins, including a complement regulatory protein. Ectromelia virus provides a mouse model for smallpox where the virus and the host's immune response have co-evolved. Using this model, our study investigated the role of the complement system during a poxvirus infection. By multiple inoculation routes, ectromelia virus caused increased mortality by 7 to 10 days post-infection in C57BL/6 mice that lack C3, the central component of the complement cascade. In C3(-/- mice, ectromelia virus disseminated earlier to target organs and generated higher peak titers compared to the congenic controls. Also, increased hepatic inflammation and necrosis correlated with these higher tissue titers and likely contributed to the morbidity in the C3(-/- mice. In vitro, the complement system in naïve C57BL/6 mouse sera neutralized ectromelia virus, primarily through the recognition of the virion by natural antibody and activation of the classical and alternative pathways. Sera deficient in classical or alternative pathway components or antibody had reduced ability to neutralize viral particles, which likely contributed to increased viral dissemination and disease severity in vivo. The increased mortality of C4(-/- or Factor B(-/- mice also indicates that these two pathways of complement activation are required for survival. In summary, the complement system acts in the first few minutes, hours, and days to control this poxviral infection until the adaptive immune response can react, and loss of this system results in lethal infection.

Dynamics of human complement-mediated killing of Klebsiella pneumoniae.

Science.gov (United States)

Nypaver, Christina M; Thornton, Margaret M; Yin, Suellen M; Bracho, David O; Nelson, Patrick W; Jones, Alan E; Bortz, David M; Younger, John G

2010-11-01

With an in vitro system that used a luminescent strain of Klebsiella pneumoniae to assess bacterial metabolic activity in near-real-time, we investigated the dynamics of complement-mediated attack in healthy individuals and in patients presenting to the emergency department with community-acquired severe sepsis. A novel mathematical/statistical model was developed to simplify light output trajectories over time into two fitted parameters, the rate of complement activation and the delay from activation to the onset of killing. Using Factor B-depleted serum, the alternative pathway was found to be the primary bactericidal effector: In the absence of B, C3 opsonization as measured by flow cytometry did not progress and bacteria proliferated near exponentially. Defects in bacterial killing were easily demonstrable in patients with severe sepsis compared with healthy volunteers. In most patients with sepsis, the rate of activation was higher than in normal subjects but was associated with a prolonged delay between activation and bacterial killing (P < 0.05 for both). Theoretical modeling suggested that this combination of accentuated but delayed function should allow successful bacterial killing but with significantly greater complement activation. The use of luminescent bacteria allowed for the development of a novel and powerful tool for assessing complement immunology for the purposes of mechanistic study and patient evaluation.

Inactivation of complement by Loxosceles reclusa spider venom.

Science.gov (United States)

Gebel, H M; Finke, J H; Elgert, K D; Cambell, B J; Barrett, J T

1979-07-01

Zymosan depletion of serum complement in guinea pigs rendered them highly resistant to lesion by Loxosceles reclusa spider venom. Guinea pigs deficient in C4 of the complement system are as sensitive to the venom as normal guinea pigs. The injection of 35 micrograms of whole recluse venom intradermally into guinea pigs lowered their complement level by 35.7%. Brown recluse spider venom in concentrations as slight as 0.02 micrograms protein/ml can totally inactivate one CH50 of guinea pig complement in vitro. Bee, scorpion, and other spider venoms had no influence on the hemolytic titer of complement. Fractionation of recluse spider venom by Sephadex G-200 filtration separated the complement-inactivating property of the venom into three major regions which could be distinguished on the basis of heat stability as well as size. None was neutralized by antivenom. Polyacrylamide gel electrophoresis of venom resolved the complement inactivators into five fractions. Complement inactivated by whole venom or the Sephadex fractions could be restored to hemolytic activity by supplements of fresh serum but not by heat-inactivated serum, pure C3, pure C5, or C3 and C5 in combination.

Complement inhibitory proteins expression in placentas of thrombophilic women Complement inhibitory proteins expression in placentas of thrombophilic women

Directory of Open Access Journals (Sweden)

Przemysław Krzysztof Wirstlein

2012-10-01

Full Text Available Factors controlling complement activation appear to exert a protective effect on pregnancy. This is
particularly important in women with thrombophilia. The aim of this study was to determine the transcript and
protein levels of complement decay-accelerating factor (DAF and membrane cofactor protein (MCP in the
placentas of women with acquired and inherited thrombophilia. Also, we assessed immunohistochemistry staining
of inhibitors of the complement cascade, DAF and MCP proteins, in the placentas of thrombophilic women.
Placentas were collected from eight women with inherited thrombophilia and ten with acquired thrombophilia.
The levels of DAF and MCP transcripts were evaluated by qPCR, the protein level was evaluated by Western
blot. We observed a higher transcript (p < 0.05 and protein (p < 0.001 levels of DAF and MCP in the placentas
of thrombophilic women than in the control group. DAF and MCP were localized on villous syncytiotrophoblast
membranes, but the assessment of staining in all groups did not differ. The observed higher expression level of
proteins that control activation of complement control proteins is only seemingly contradictory to the changes
observed for example in the antiphospholipid syndrome. However, given the hitherto known biochemical changes
associated with thrombophilia, a mechanism in which increased expression of DAF and MCP in the placentas is
an effect of proinflammatory cytokines, which accompanies thrombophilia, is probable.Factors controlling complement activation appear to exert a protective effect on pregnancy. This is
particularly important in women with thrombophilia. The aim of this study was to determine the transcript and
protein levels of complement decay-accelerating factor (DAF and membrane cofactor protein (MCP in the
placentas of women with acquired and inherited thrombophilia. Also, we assessed immunohistochemistry

Effects of radiographic contrast media on the serum complement system

International Nuclear Information System (INIS)

Tirone, P.; Boldrini, E.

1983-01-01

The authors explored the activation of the complement system produced by a nonionic organic iodine compound, namely iopamidol, which is proposed as a contrast medium for radiographic examination by intravenous and intra-arterial injection. The study was conducted in vitro versus established ionic contrasts (diatrizoate, iothalamate, acetrizoate) and a nonionic compound (metrizamide). The adopted experimental model was the immunohemolytic detector system, in which the immune complex consisted of goat erythrocytes sensitized with the corresponding antibody (hemolysin), and complement (C') was supplied by guinea pig serum. All the products caused complement activation. The results show that nonionic contrast media produce less activation of the complement system than the traditional ionic contrast. Thus the use of nonionic contrast for radiological procedures necessitating the introduction of contrast material into the blood compartment would imply a reduced risk of anaphylactoid reactions. (orig.)

Is complement good, bad, or both? New functions of the complement factors associated with inflammation mechanisms in the central nervous system.

Science.gov (United States)

Tahtouh, Muriel; Croq, Françoise; Lefebvre, Christophe; Pestel, Joël

2009-09-01

The complement system is well known as an enzyme cascade that helps to defend against infections. Indeed, this ancestral system bridges innate and adaptive immunity. Its implication in diseases of the central nervous system (CNS), has led to an increased number of studies. Complement activation in the CNS has been generally considered to contribute to tissue damage. However, recent studies suggest that complement may be neuroprotective, and can participate in maintenance and repair of the adult brain. Here, we will review this dual role of complement proteins and some of their functional interactions with part of the chemokine and cytokine network associated with the protection of CNS integrity.

The complement system and its role in the pathogenesis of periodontitis

DEFF Research Database (Denmark)

Damgaard, Christian; Holmstrup, Palle; Van Dyke, Thomas E.

2015-01-01

Periodontitis is a highly prevalent inflammatory disease in tooth supporting tissues, induced by bacteria growing in a biofilm on tooth surfaces. Components of the complement system are present in the periodontal tissue and the system is activated in periodontitis. Continuous complement activation...... and modulation by bacteria within the biofilm in periodontal pockets, however, may enhance local tissue destruction, providing the biofilm with both essential nutrients and space to grow. A more profound understanding of the mechanisms involved in complement-derived tissue degradation may facilitate...... with an emphasis on interaction of complement with bacteria from periodontitis-associated biofilm....

Solid-phase classical complement activation by C-reactive protein (CRP) is inhibited by fluid-phase CRP-C1q interaction

International Nuclear Information System (INIS)

Sjoewall, Christopher; Wetteroe, Jonas; Bengtsson, Torbjoern; Askendal, Agneta; Almroth, Gunnel; Skogh, Thomas; Tengvall, Pentti

2007-01-01

C-reactive protein (CRP) interacts with phosphorylcholine (PC), Fcγ receptors, complement factor C1q and cell nuclear constituents, yet its biological roles are insufficiently understood. The aim was to characterize CRP-induced complement activation by ellipsometry. PC conjugated with keyhole limpet hemocyanin (PC-KLH) was immobilized to cross-linked fibrinogen. A low-CRP serum with different amounts of added CRP was exposed to the PC-surfaces. The total serum protein deposition was quantified and deposition of IgG, C1q, C3c, C4, factor H, and CRP detected with polyclonal antibodies. The binding of serum CRP to PC-KLH dose-dependently triggered activation of the classical pathway. Unexpectedly, the activation was efficiently down-regulated at CRP levels >150 mg/L. Using radial immunodiffusion, CRP-C1q interaction was observed in serum samples with high CRP concentrations. We propose that the underlying mechanism depends on fluid-phase interaction between C1q and CRP. This might constitute another level of complement regulation, which has implications for systemic lupus erythematosus where CRP is often low despite flare-ups

Novel roles of complement in renal diseases and their therapeutic consequences.

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Wada, Takehiko; Nangaku, Masaomi

2013-09-01

The complement system functions as a part of the innate immune system. Inappropriate activation of the complement pathways has a deleterious effect on kidneys. Recent advances in complement research have provided new insights into the pathogenesis of glomerular and tubulointerstitial injury associated with complement activation. A new disease entity termed 'C3 glomerulopathy' has recently been proposed and is characterized by isolated C3 deposition in glomeruli without positive staining for immunoglobulins. Genetic and functional studies have demonstrated that several different mutations and disease variants, as well as the generation of autoantibodies, are potentially associated with its pathogenesis. The data from comprehensive analyses suggest that complement dysregulation can also be associated with hemolytic uremic syndrome and more common glomerular diseases, such as IgA nephropathy and diabetic kidney disease. In addition, animal studies utilizing genetically modified mice have begun to elucidate the molecular pathomechanisms associated with the complement system. From a diagnostic point of view, a noninvasive, MRI-based method for detecting C3 has recently been developed to serve as a novel tool for diagnosing complement-mediated kidney diseases. While novel therapeutic tools related to complement regulation are emerging, studies evaluating the precise roles of the complement system in kidney diseases will still be useful for developing new therapeutic approaches.

Infusion Reactions Associated with the Medical Application of Monoclonal Antibodies: The Role of Complement Activation and Possibility of Inhibition by Factor H

OpenAIRE

Tamás Fülöp; Tamás Mészáros; Gergely Tibor Kozma; János Szebeni; Mihály Józsi

2018-01-01

Human application of monoclonal antibodies (mAbs), enzymes, as well as contrast media and many other particulate drugs and agents referred to as “nanomedicines”, can initiate pseudoallergic hypersensitivity reactions, also known as infusion reactions. These may in part be mediated by the activation of the complement system, a major humoral defense system of innate immunity. In this review, we provide a brief outline of complement activation-related pseudoallergy (CARPA) in general, and then f...

Alternative complement pathway and factor B activities in rats with altered blood levels of thyroid hormone

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Bitencourt, C.S. [Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Duarte, C.G.; Azzolini, A.E.C.S.; Assis-Pandochi, A.I. [Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil)

2012-03-02

Evaluating the activity of the complement system under conditions of altered thyroid hormone levels might help elucidate the role of complement in triggering autoimmune processes. Here, we investigated alternative pathway (AP) activity in male Wistar rats (180 ± 10 g) after altering their thyroid hormone levels by treatment with triiodothyronine (T3), propylthiouracil (PTU) or thyroidectomy. T3 and thyroxine (T4) levels were determined by chemiluminescence assays. Hemolytic assays were performed to evaluate the lytic activity of the AP. Factor B activity was evaluated using factor B-deficient serum. An anti-human factor B antibody was used to measure factor B levels in serum by radial immunodiffusion. T3 measurements in thyroidectomized animals or animals treated with PTU demonstrated a significant reduction in hormone levels compared to control. The results showed a reduction in AP lytic activity in rats treated with increasing amounts of T3 (1, 10, or 50 µg). Factor B activity was also decreased in the sera of hyperthyroid rats treated with 1 to 50 µg T3. Additionally, treating rats with 25 µg T3 significantly increased factor B levels in their sera (P < 0.01). In contrast, increased factor B concentration and activity (32%) were observed in hypothyroid rats. We conclude that alterations in thyroid hormone levels affect the activity of the AP and factor B, which may in turn affect the roles of AP and factor B in antibody production.

Alternative complement pathway and factor B activities in rats with altered blood levels of thyroid hormone

International Nuclear Information System (INIS)

Bitencourt, C.S.; Duarte, C.G.; Azzolini, A.E.C.S.; Assis-Pandochi, A.I.

2012-01-01

Evaluating the activity of the complement system under conditions of altered thyroid hormone levels might help elucidate the role of complement in triggering autoimmune processes. Here, we investigated alternative pathway (AP) activity in male Wistar rats (180 ± 10 g) after altering their thyroid hormone levels by treatment with triiodothyronine (T3), propylthiouracil (PTU) or thyroidectomy. T3 and thyroxine (T4) levels were determined by chemiluminescence assays. Hemolytic assays were performed to evaluate the lytic activity of the AP. Factor B activity was evaluated using factor B-deficient serum. An anti-human factor B antibody was used to measure factor B levels in serum by radial immunodiffusion. T3 measurements in thyroidectomized animals or animals treated with PTU demonstrated a significant reduction in hormone levels compared to control. The results showed a reduction in AP lytic activity in rats treated with increasing amounts of T3 (1, 10, or 50 µg). Factor B activity was also decreased in the sera of hyperthyroid rats treated with 1 to 50 µg T3. Additionally, treating rats with 25 µg T3 significantly increased factor B levels in their sera (P < 0.01). In contrast, increased factor B concentration and activity (32%) were observed in hypothyroid rats. We conclude that alterations in thyroid hormone levels affect the activity of the AP and factor B, which may in turn affect the roles of AP and factor B in antibody production

Site-targeted complement inhibition by a complement receptor 2-conjugated inhibitor (mTT30) ameliorates post-injury neuropathology in mouse brains.

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Rich, Megan C; Keene, Chesleigh N; Neher, Miriam D; Johnson, Krista; Yu, Zhao-Xue; Ganivet, Antoine; Holers, V Michael; Stahel, Philip F

2016-03-23

Intracerebral complement activation after severe traumatic brain injury (TBI) leads to a cascade of neuroinflammatory pathological sequelae that propagate host-mediated secondary brain injury and adverse outcomes. There are currently no specific pharmacological agents on the market to prevent or mitigate the development of secondary cerebral insults after TBI. A novel chimeric CR2-fH compound (mTT30) provides targeted inhibition of the alternative complement pathway at the site of tissue injury. This experimental study was designed to test the neuroprotective effects of mTT30 in a mouse model of closed head injury. The administration of 500 μg mTT30 i.v. at 1 h, 4 h and 24 h after head injury attenuated complement C3 deposition in injured brains, reduced the extent of neuronal cell death, and decreased post-injury microglial activation, compared to vehicle-injected placebo controls. These data imply that site-targeted alternative pathway complement inhibition may represent a new promising therapeutic avenue for the future management of severe TBI. Copyright © 2016. Published by Elsevier Ireland Ltd.

In Situ complement activation and T-cell immunity in leprosy spectrum: An immunohistological study on leprosy lesional skin.

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Bahia El Idrissi, Nawal; Iyer, Anand M; Ramaglia, Valeria; Rosa, Patricia S; Soares, Cleverson T; Baas, Frank; Das, Pranab K

2017-01-01

Mycobacterium leprae (M. leprae) infection causes nerve damage and the condition worsens often during and long after treatment. Clearance of bacterial antigens including lipoarabinomannan (LAM) during and after treatment in leprosy patients is slow. We previously demonstrated that M. leprae LAM damages peripheral nerves by in situ generation of the membrane attack complex (MAC). Investigating the role of complement activation in skin lesions of leprosy patients might provide insight into the dynamics of in situ immune reactivity and the destructive pathology of M. leprae. In this study, we analyzed in skin lesions of leprosy patients, whether M. leprae antigen LAM deposition correlates with the deposition of complement activation products MAC and C3d on nerves and cells in the surrounding tissue. Skin biopsies of paucibacillary (n = 7), multibacillary leprosy patients (n = 7), and patients with erythema nodosum leprosum (ENL) (n = 6) or reversal reaction (RR) (n = 4) and controls (n = 5) were analyzed. The percentage of C3d, MAC and LAM deposition was significantly higher in the skin biopsies of multibacillary compared to paucibacillary patients (p = leprosy patients (r = 0.9578, pleprosy patients (p = leprosy patients, suggesting that inflammation driven by complement activation might contribute to nerve damage in the lesions of these patients. This should be regarded as an important factor in M. leprae nerve damage pathology.

Spores of Mucor ramosissimus, Mucor plumbeus and Mucor circinelloides and their ability to activate human complement system in vitro.

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Granja, Luiz Fernando Zmetek; Pinto, Lysianne; Almeida, Cátia Amancio; Alviano, Daniela Sales; Da Silva, Maria Helena; Ejzemberg, Regina; Alviano, Celuta Sales

2010-03-01

Complement activation by spores of Mucor ramosissimus, Mucor plumbeus and Mucor circinelloides was studied using absorbed human serum in the presence or absence of chelators (EGTA or EDTA). We found that the spore caused full complement activation when incubated with EGTA-Mg2+ or without chelators, indicating that the alternative pathway is mainly responsible for this response. In order to compare activation profiles from each species, ELISAs for C3 and C4 fragments, mannan binding lectin (MBL), C-reactive protein (CRP) and IgG studies were carried out. All proteins were present on the species tested. Immunofluorescence tests demonstrated the presence of C3 fragments on the surface of all samples, which were confluent throughout fungal surfaces. The same profile of C3, C4, MBL, CRP and IgG deposition, observed in all species, suggests a similar activation behavior for these species.

Complement propriety and conspiracy in nanomedicine

DEFF Research Database (Denmark)

Moghimi, Seyed Moein

2016-01-01

The complement system is the first line of body's defense against intruders and it acts as a functional bridge between innate and adaptive arms of the immune system. This commentary examines the key roles of complement activation in response to nanomedicine administration, including nucleic acid...... complexes. These comprise beneficial (eg, adjuvanticity) as well as adverse effects (eg, infusion-related reactions). Pigs (and sheep) are often used as predictive models of nanomedicine-mediated infusion-related reactions in humans. The validity of these models in relation to human responses is questioned...

Pasteurella pneumotropica evades the human complement system by acquisition of the complement regulators factor H and C4BP.

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Alfredo Sahagún-Ruiz

Full Text Available Pasteurella pneumotropica is an opportunist Gram negative bacterium responsible for rodent pasteurellosis that affects upper respiratory, reproductive and digestive tracts of mammals. In animal care facilities the presence of P. pneumotropica causes severe to lethal infection in immunodeficient mice, being also a potential source for human contamination. Indeed, occupational exposure is one of the main causes of human infection by P. pneumotropica. The clinical presentation of the disease includes subcutaneous abscesses, respiratory tract colonization and systemic infections. Given the ability of P. pneumotropica to fully disseminate in the organism, it is quite relevant to study the role of the complement system to control the infection as well as the possible evasion mechanisms involved in bacterial survival. Here, we show for the first time that P. pneumotropica is able to survive the bactericidal activity of the human complement system. We observed that host regulatory complement C4BP and Factor H bind to the surface of P. pneumotropica, controlling the activation pathways regulating the formation and maintenance of C3-convertases. These results show that P. pneumotropica has evolved mechanisms to evade the human complement system that may increase the efficiency by which this pathogen is able to gain access to and colonize inner tissues where it may cause severe infections.

Plasma complement biomarkers distinguish multiple sclerosis and neuromyelitis optica spectrum disorder.

Science.gov (United States)

Hakobyan, Svetlana; Luppe, Sebastian; Evans, David Rs; Harding, Katharine; Loveless, Samantha; Robertson, Neil P; Morgan, B Paul

2017-06-01

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) are autoimmune inflammatory demyelinating diseases of the central nervous system. Although distinguished by clinicoradiological and demographic features, early manifestations can be similar complicating management. Antibodies against aquaporin-4 support the diagnosis of NMOSD but are negative in some patients. Therefore, there is unmet need for biomarkers that enable early diagnosis and disease-specific intervention. We investigated whether plasma complement proteins are altered in MS and NMOSD and provide biomarkers that distinguish these diseases. Plasma from 54 NMOSD, 40 MS and 69 control donors was tested in multiplex assays measuring complement activation products and proteins. Using logistic regression, we tested whether combinations of complement analytes distinguished NMOSD from controls and MS. All activation products were elevated in NMOSD compared to either control or MS. Four complement proteins (C1inh, C1s, C5 and FH) were higher in NMOSD compared to MS or controls. A model comprising C1inh and terminal complement complex (TCC) distinguished NMOSD from MS (area under the curve (AUC): 0.98), while C1inh and C5 distinguished NMOSD from controls (AUC: 0.94). NMOSD is distinguished from MS by plasma complement biomarkers. Selected complement analytes enable differential diagnosis. Findings support trials of anti-complement therapies in NMOSD.

Evasion Mechanisms Used by Pathogens to Escape the Lectin Complement Pathway

DEFF Research Database (Denmark)

Rosbjerg, Anne; Genster, Ninette; Pilely, Katrine

2017-01-01

the level of activity. The result is a pro-inflammatory response meant to combat foreign microbes. Microbial elimination is, however, not a straight forward procedure; pathogens have adapted to their environment by evolving a collection of evasion mechanisms that circumvent the human complement system....... Complement evasion strategies features different ways of exploiting human complement proteins and moreover features different pathogen-derived proteins that interfere with the normal processes. Accumulated, these mechanisms target all three complement activation pathways as well as the final common part...... of the cascade. This review will cover the currently known lectin pathway evasion mechanisms and give examples of pathogens that operate these to increase their chance of invasion, survival and dissemination....

Complement activating soluble pattern recognition molecules with collagen-like regions, mannan-binding lectin, ficolins and associated proteins

DEFF Research Database (Denmark)

Thiel, Steffen

2007-01-01

Mannan-binding lectin (MBL), L-ficolin, M-ficolin and H-ficolin are all complement activating soluble pattern recognition molecules with recognition domains linked to collagen-like regions. All four may form complexes with four structurally related proteins, the three MBL-associated serine...... proteases (MASPs), MASP-1, MASP-2 and MASP-3, and a smaller MBL-associated protein (MAp19). The four recognition molecules recognize patterns of carbohydrate or acetyl-group containing ligands. After binding to the relevant targets all four are able to activate the complement system. We thus have a system...... where four different and/or overlapping patterns of microbial origin or patterns of altered-self may be recognized, but in all cases the signalling molecules, the MASPs, are shared. MASP-1 and MASP-3 are formed from one gene, MASP1/3, by alternative splicing generating two different mRNAs from a single...

Evasion Mechanisms Used by Pathogens to Escape the Lectin Complement Pathway.

Science.gov (United States)

Rosbjerg, Anne; Genster, Ninette; Pilely, Katrine; Garred, Peter

2017-01-01

The complement system is a crucial defensive network that protects the host against invading pathogens. It is part of the innate immune system and can be initiated via three pathways: the lectin, classical and alternative activation pathway. Overall the network compiles a group of recognition molecules that bind specific patterns on microbial surfaces, a group of associated proteases that initiates the complement cascade, and a group of proteins that interact in proteolytic complexes or the terminal pore-forming complex. In addition, various regulatory proteins are important for controlling the level of activity. The result is a pro-inflammatory response meant to combat foreign microbes. Microbial elimination is, however, not a straight forward procedure; pathogens have adapted to their environment by evolving a collection of evasion mechanisms that circumvent the human complement system. Complement evasion strategies features different ways of exploiting human complement proteins and moreover features different pathogen-derived proteins that interfere with the normal processes. Accumulated, these mechanisms target all three complement activation pathways as well as the final common part of the cascade. This review will cover the currently known lectin pathway evasion mechanisms and give examples of pathogens that operate these to increase their chance of invasion, survival and dissemination.

Acute Systolic Heart Failure Associated with Complement-Mediated Hemolytic Uremic Syndrome

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John L. Vaughn

2015-01-01

Full Text Available Complement-mediated hemolytic uremic syndrome (otherwise known as atypical HUS is a rare disorder of uncontrolled complement activation that may be associated with heart failure. We report the case of a 49-year-old female with no history of heart disease who presented with microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Given her normal ADAMSTS13 activity, evidence of increased complement activation, and renal biopsy showing evidence of thrombotic microangiopathy, she was diagnosed with complement-mediated HUS. She subsequently developed acute hypoxemic respiratory failure secondary to pulmonary edema requiring intubation and mechanical ventilation. A transthoracic echocardiogram showed evidence of a Takotsubo cardiomyopathy with an estimated left ventricular ejection fraction of 20%, though ischemic cardiomyopathy could not be ruled out. Treatment was initiated with eculizumab. After several failed attempts at extubation, she eventually underwent tracheotomy. She also required hemodialysis to improve her uremia and hypervolemia. After seven weeks of hospitalization and five doses of eculizumab, her renal function and respiratory status improved, and she was discharged in stable condition on room air and independent of hemodialysis. Our case illustrates a rare association between acute systolic heart failure and complement-mediated HUS and highlights the potential of eculizumab in stabilizing even the most critically-ill patients with complement-mediated disease.

Retinal pigment epithelial cells upregulate expression of complement factors after co-culture with activated T cells

DEFF Research Database (Denmark)

Juel, Helene Bæk; Kaestel, Charlotte; Folkersen, Lasse

2011-01-01

In this study we examined the effect of T cell-derived cytokines on retinal pigment epithelial (RPE) cells with respect to expression of complement components. We used an in vitro co-culture system in which CD3/CD28-activated human T cells were separated from the human RPE cell line (ARPE-19...

Complement drives glucosylceramide accumulation and tissue inflammation in Gaucher disease.

Science.gov (United States)

Pandey, Manoj K; Burrow, Thomas A; Rani, Reena; Martin, Lisa J; Witte, David; Setchell, Kenneth D; Mckay, Mary A; Magnusen, Albert F; Zhang, Wujuan; Liou, Benjamin; Köhl, Jörg; Grabowski, Gregory A

2017-03-02

Gaucher disease is caused by mutations in GBA1, which encodes the lysosomal enzyme glucocerebrosidase (GCase). GBA1 mutations drive extensive accumulation of glucosylceramide (GC) in multiple innate and adaptive immune cells in the spleen, liver, lung and bone marrow, often leading to chronic inflammation. The mechanisms that connect excess GC to tissue inflammation remain unknown. Here we show that activation of complement C5a and C5a receptor 1 (C5aR1) controls GC accumulation and the inflammatory response in experimental and clinical Gaucher disease. Marked local and systemic complement activation occurred in GCase-deficient mice or after pharmacological inhibition of GCase and was associated with GC storage, tissue inflammation and proinflammatory cytokine production. Whereas all GCase-inhibited mice died within 4-5 weeks, mice deficient in both GCase and C5aR1, and wild-type mice in which GCase and C5aR were pharmacologically inhibited, were protected from these adverse effects and consequently survived. In mice and humans, GCase deficiency was associated with strong formation of complement-activating GC-specific IgG autoantibodies, leading to complement activation and C5a generation. Subsequent C5aR1 activation controlled UDP-glucose ceramide glucosyltransferase production, thereby tipping the balance between GC formation and degradation. Thus, extensive GC storage induces complement-activating IgG autoantibodies that drive a pathway of C5a generation and C5aR1 activation that fuels a cycle of cellular GC accumulation, innate and adaptive immune cell recruitment and activation in Gaucher disease. As enzyme replacement and substrate reduction therapies are expensive and still associated with inflammation, increased risk of cancer and Parkinson disease, targeting C5aR1 may serve as a treatment option for patients with Gaucher disease and, possibly, other lysosomal storage diseases.

Complement activation as a bioequivalence issue relevant to the development of generic liposomes and other nanoparticulate drugs

Energy Technology Data Exchange (ETDEWEB)

Szebeni, Janos, E-mail: jszebeni2@gmail.com [Nanomedicine Research and Education Center, Semmelweis University, Budapest & SeroScience Ltd, Budapest (Hungary); Storm, Gert [Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, Utrecht (Netherlands)

2015-12-18

Liposomes are known to activate the complement (C) system, which can lead in vivo to a hypersensitivity syndrome called C activation-related pseudoallergy (CARPA). CARPA has been getting increasing attention as a safety risk of i.v. therapy with liposomes, whose testing is now recommended in bioequivalence evaluations of generic liposomal drug candidates. This review highlights the adverse consequences of C activation, the unique symptoms of CARPA triggered by essentially all i.v. administered liposomal drugs, and the various features of vesicles influencing this adverse immune effect. For the case of Doxil, we also address the mechanism of C activation and the opsonization vs. long circulation (stealth) paradox. In reviewing the methods of assessing C activation and CARPA, we delineate the most sensitive porcine model and an algorithm for stepwise evaluation of the CARPA risk of i.v. liposomes, which are proposed for standardization for preclinical toxicology evaluation of liposomal and other nanoparticulate drug candidates. - Highlights: • Outlining of difficulties in generic development of liposomal drugs. • New regulatory requirements to evaluate CARPA in preclinical studies. • Review of complement activation by liposomes and its adverse consequences (CARPA). • Assays of C activation in vitro and CARPA in vivo, with the porcine test in focus. • Decision tree how to handle the risk of CARPA assessed by a battery of tests.

Complement activation as a bioequivalence issue relevant to the development of generic liposomes and other nanoparticulate drugs

International Nuclear Information System (INIS)

Szebeni, Janos; Storm, Gert

2015-01-01

Liposomes are known to activate the complement (C) system, which can lead in vivo to a hypersensitivity syndrome called C activation-related pseudoallergy (CARPA). CARPA has been getting increasing attention as a safety risk of i.v. therapy with liposomes, whose testing is now recommended in bioequivalence evaluations of generic liposomal drug candidates. This review highlights the adverse consequences of C activation, the unique symptoms of CARPA triggered by essentially all i.v. administered liposomal drugs, and the various features of vesicles influencing this adverse immune effect. For the case of Doxil, we also address the mechanism of C activation and the opsonization vs. long circulation (stealth) paradox. In reviewing the methods of assessing C activation and CARPA, we delineate the most sensitive porcine model and an algorithm for stepwise evaluation of the CARPA risk of i.v. liposomes, which are proposed for standardization for preclinical toxicology evaluation of liposomal and other nanoparticulate drug candidates. - Highlights: • Outlining of difficulties in generic development of liposomal drugs. • New regulatory requirements to evaluate CARPA in preclinical studies. • Review of complement activation by liposomes and its adverse consequences (CARPA). • Assays of C activation in vitro and CARPA in vivo, with the porcine test in focus. • Decision tree how to handle the risk of CARPA assessed by a battery of tests.

Genetic, molecular and functional analyses of complement factor I deficiency

DEFF Research Database (Denmark)

Nilsson, S.C.; Trouw, L.A.; Renault, N.

2009-01-01

Complete deficiency of complement inhibitor factor I (FI) results in secondary complement deficiency due to uncontrolled spontaneous alternative pathway activation leading to susceptibility to infections. Current genetic examination of two patients with near complete FI deficiency and three patie...

Oral vaccination with heat inactivated Mycobacterium bovis activates the complement system to protect against tuberculosis.

Directory of Open Access Journals (Sweden)

Beatriz Beltrán-Beck

Full Text Available Tuberculosis (TB remains a pandemic affecting billions of people worldwide, thus stressing the need for new vaccines. Defining the correlates of vaccine protection is essential to achieve this goal. In this study, we used the wild boar model for mycobacterial infection and TB to characterize the protective mechanisms elicited by a new heat inactivated Mycobacterium bovis vaccine (IV. Oral vaccination with the IV resulted in significantly lower culture and lesion scores, particularly in the thorax, suggesting that the IV might provide a novel vaccine for TB control with special impact on the prevention of pulmonary disease, which is one of the limitations of current vaccines. Oral vaccination with the IV induced an adaptive antibody response and activation of the innate immune response including the complement component C3 and inflammasome. Mycobacterial DNA/RNA was not involved in inflammasome activation but increased C3 production by a still unknown mechanism. The results also suggested a protective mechanism mediated by the activation of IFN-γ producing CD8+ T cells by MHC I antigen presenting dendritic cells (DCs in response to vaccination with the IV, without a clear role for Th1 CD4+ T cells. These results support a role for DCs in triggering the immune response to the IV through a mechanism similar to the phagocyte response to PAMPs with a central role for C3 in protection against mycobacterial infection. Higher C3 levels may allow increased opsonophagocytosis and effective bacterial clearance, while interfering with CR3-mediated opsonic and nonopsonic phagocytosis of mycobacteria, a process that could be enhanced by specific antibodies against mycobacterial proteins induced by vaccination with the IV. These results suggest that the IV acts through novel mechanisms to protect against TB in wild boar.

Early Components of the Complement Classical Activation Pathway in Human Systemic Autoimmune Diseases

Science.gov (United States)

Lintner, Katherine E.; Wu, Yee Ling; Yang, Yan; Spencer, Charles H.; Hauptmann, Georges; Hebert, Lee A.; Atkinson, John P.; Yu, C. Yung

2016-01-01

The complement system consists of effector proteins, regulators, and receptors that participate in host defense against pathogens. Activation of the complement system, via the classical pathway (CP), has long been recognized in immune complex-mediated tissue injury, most notably systemic lupus erythematosus (SLE). Paradoxically, a complete deficiency of an early component of the CP, as evidenced by homozygous genetic deficiencies reported in human, are strongly associated with the risk of developing SLE or a lupus-like disease. Similarly, isotype deficiency attributable to a gene copy-number (GCN) variation and/or the presence of autoantibodies directed against a CP component or a regulatory protein that result in an acquired deficiency are relatively common in SLE patients. Applying accurate assay methodologies with rigorous data validations, low GCNs of total C4, and heterozygous and homozygous deficiencies of C4A have been shown as medium to large effect size risk factors, while high copy numbers of total C4 or C4A as prevalent protective factors, of European and East-Asian SLE. Here, we summarize the current knowledge related to genetic deficiency and insufficiency, and acquired protein deficiencies for C1q, C1r, C1s, C4A/C4B, and C2 in disease pathogenesis and prognosis of SLE, and, briefly, for other systemic autoimmune diseases. As the complement system is increasingly found to be associated with autoimmune diseases and immune-mediated diseases, it has become an attractive therapeutic target. We highlight the recent developments and offer a balanced perspective concerning future investigations and therapeutic applications with a focus on early components of the CP in human systemic autoimmune diseases. PMID:26913032

A potent complement factor C3 specific nanobody inhibiting multiple functions in the alternative pathway of human and murine complement

DEFF Research Database (Denmark)

Jensen, Rasmus K; Pihl, Rasmus; Gadeberg, Trine A F

2018-01-01

The complement system is a complex, carefully regulated proteolytic cascade for which suppression of aberrant activation is of increasing clinical relevance and inhibition of the complement alternative pathway is a subject of intense research. Here, we describe the nanobody hC3Nb1 that binds...... to multiple functional states of C3 with sub-nanomolar affinity. The nanobody causes a complete shutdown of alternative pathway activity in human and murine serum when present in concentrations comparable to C3, and hC3Nb1 is shown to prevent both proconvertase assembly as well as binding of the C3 substrate...... to C3 convertases. Our crystal structure of the C3b-hC3Nb1 complex and functional experiments demonstrate that proconvertase formation is blocked by steric hindrance between the nanobody and an Asn-linked glycan on complement factor B. In addition, hC3Nb1 is shown to prevent factor H binding to C3b...

Plasma-derived human C1-esterase inhibitor does not prevent mechanical ventilation-induced pulmonary complement activation in a rat model of Streptococcus pneumoniae pneumonia

NARCIS (Netherlands)

de Beer, F. M.; Aslami, H.; Hoeksma, J.; van Mierlo, G.; Wouters, D.; Zeerleder, S.; Roelofs, J. J. T. H.; Juffermans, N. P.; Schultz, M. J.; Lagrand, W. K.

2014-01-01

Mechanical ventilation has the potential to cause lung injury, and the role of complement activation herein is uncertain. We hypothesized that inhibition of the complement cascade by administration of plasma-derived human C1-esterase inhibitor (C1-INH) prevents ventilation-induced pulmonary

Arthrogenicity of type II collagen monoclonal antibodies associated with complement activation and antigen affinity

OpenAIRE

Koobkokkruad, Thongchai; Kadotani, Tatsuya; Hutamekalin, Pilaiwanwadee; Mizutani, Nobuaki; Yoshino, Shin

2011-01-01

Abstract Background The collagen antibody-induced arthritis (CAIA) model, which employs a cocktail of monoclonal antibodies (mAbs) to type II collagen (CII), has been widely used for studying the pathogenesis of autoimmune arthritis. In this model, not all mAbs to CII are capable of inducing arthritis because one of the initial events is the formation of collagen-antibody immune complexes on the cartilage surface or in the synovium, and subsequent activation of the complement by the complexes...

Complement in the Initiation and Evolution of Rheumatoid Arthritis

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Holers, V. Michael; Banda, Nirmal K.

2018-01-01

The complement system is a major component of the immune system and plays a central role in many protective immune processes, including circulating immune complex processing and clearance, recognition of foreign antigens, modulation of humoral and cellular immunity, removal of apoptotic and dead cells, and engagement of injury resolving and tissue regeneration processes. In stark contrast to these beneficial roles, however, inadequately controlled complement activation underlies the pathogenesis of human inflammatory and autoimmune diseases, including rheumatoid arthritis (RA) where the cartilage, bone, and synovium are targeted. Recent studies of this disease have demonstrated that the autoimmune response evolves over time in an asymptomatic preclinical phase that is associated with mucosal inflammation. Notably, experimental models of this disease have demonstrated that each of the three major complement activation pathways plays an important role in recognition of injured joint tissue, although the lectin and amplification pathways exhibit particularly impactful roles in the initiation and amplification of damage. Herein, we review the complement system and focus on its multi-factorial role in human patients with RA and experimental murine models. This understanding will be important to the successful integration of the emerging complement therapeutics pipeline into clinical care for patients with RA. PMID:29892280

Complement-mediated tumour growth: implications for cancer nanotechnology and nanomedicines

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Moghimi, S. M.; Andresen, Thomas Lars

2009-01-01

The recent unexpected observation that complement activation helps turnout growth and progression has an important bearing on the future development of cancer nanomedicines for site-specific tumour targeting as these entities are capable of triggering complement. These issues are discussed and su...

Virulence of Group A Streptococci Is Enhanced by Human Complement Inhibitors

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Ermert, David; Shaughnessy, Jutamas; Joeris, Thorsten

2015-01-01

Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is an important human bacterial pathogen that can cause invasive infections. Once it colonizes its exclusively human host, GAS needs to surmount numerous innate immune defense mechanisms, including opsonization by complement and c...... in studies of GAS pathogenesis and for developing vaccines and therapeutics that rely on human complement activation for efficacy.......Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is an important human bacterial pathogen that can cause invasive infections. Once it colonizes its exclusively human host, GAS needs to surmount numerous innate immune defense mechanisms, including opsonization by complement...... and consequent phagocytosis. Several strains of GAS bind to human-specific complement inhibitors, C4b-binding protein (C4BP) and/or Factor H (FH), to curtail complement C3 (a critical opsonin) deposition. This results in diminished activation of phagocytes and clearance of GAS that may lead to the host being...

Reincarnation of ancient links between coagulation and complement.

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Conway, E M

2015-06-01

Throughout evolution, organisms have developed means to contain wounds by simultaneously limiting bleeding and eliminating pathogens and damaged host cells via the recruitment of innate defense mechanisms. Disease emerges when there is unchecked activation of innate immune and/or coagulation responses. A key component of innate immunity is the complement system. Concurrent excess activation of coagulation and complement - two major blood-borne proteolytic pathways - is evident in numerous diseases, including atherosclerosis, diabetes, venous thromboembolic disease, thrombotic microangiopathies, arthritis, cancer, and infectious diseases. Delineating the cross-talk between these two cascades will uncover novel therapeutic insights. © 2015 International Society on Thrombosis and Haemostasis.

Relative Contribution of Cellular Complement Inhibitors CD59, CD46, and CD55 to Parainfluenza Virus 5 Inhibition of Complement-Mediated Neutralization

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Yujia Li

2018-04-01

Full Text Available The complement system is a part of the innate immune system that viruses need to face during infections. Many viruses incorporate cellular regulators of complement activation (RCA to block complement pathways and our prior work has shown that Parainfluenza virus 5 (PIV5 incorporates CD55 and CD46 to delay complement-mediated neutralization. In this paper, we tested the role of a third individual RCA inhibitor CD59 in PIV5 interactions with complement pathways. Using a cell line engineered to express CD59, we show that small levels of functional CD59 are associated with progeny PIV5, which is capable of blocking assembly of the C5b-C9 membrane attack complex (MAC. PIV5 containing CD59 (PIV5-CD59 showed increased resistance to complement-mediated neutralization in vitro comparing to PIV5 lacking regulators. Infection of A549 cells with PIV5 and RSV upregulated CD59 expression. TGF-beta treatment of PIV5-infected cells also increased cell surface CD59 expression and progeny virions were more resistant to complement-mediated neutralization. A comparison of individual viruses containing only CD55, CD46, or CD59 showed a potency of inhibiting complement-mediated neutralization, which followed a pattern of CD55 > CD46 > CD59.

Visceral perfusion abnormalities following complement activation. Clues to the mediators of organ ischemia in trauma and sepsis. First place winner: Conrad Jobst Award.

Science.gov (United States)

Schirmer, W J; Schirmer, J M; Naff, G B; Fry, D E

1988-12-01

Complement, activated during infection and injury, has been implicated as a mediator of microvascular injury and obstruction. This study examines how two potent activators of complement, zymosan, and cobra venom factor (CVF), affect systemic and visceral perfusion. Rats were injected with either saline (1 ml/kg), zymosan (5 mg/kg) or CVF (5 units/kg) at t = 0 and 30 minutes. Thermodilution cardiac output, mean arterial pressure, heart rate, systemic vascular resistance, and hematocrit were determined at t = 2 hours. Effective hepatic and renal blood flows, by clearance of galactose and p-aminohippurate respectively, were determined over the next hour. The per cent change in total hemolytic complement from t = 0 to t = 3 hours was determined by immune hemolysis of sheep erythrocytes. There was no difference in systemic hemodynamic parameters between the three groups. Hepatic blood flow was depressed in both the zymosan (3.83 +/- 0.23 ml/min/100 g) and CVF (3.72 +/- 0.20 ml/min/100 g) groups compared with controls (4.62 +/- 0.19 ml/min/100 g, P less than 0.05). Renal blood flow in the zymosan-treated group (6.40 +/- 0.24 ml/min/100 g) increased over control (4.80 +/- 0.40 ml/min/100 g, P less than 0.05) but was unchanged in the CVF group (5.06 +/- 0.23 ml/min/100 g). The amount of complement activated correlated with the change in hepatic (r = -0.419, P less than 0.05) but not renal (r = -0.008, P = 0.917) flow. Complement activation may occupy a proximal position in the pathogenesis of hepatic ischemia associated with trauma and sepsis.

CR2-mediated activation of the complement alternative pathway results in formation of membrane attack complexes on human B lymphocytes

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Nielsen, C H; Marquart, H V; Prodinger, W M

2001-01-01

the alternative pathway. Blockade of the CR2 ligand-binding site with the monoclonal antibody FE8 resulted in 56 +/- 13% and 71 +/- 9% inhibition of the C3-fragment and MAC deposition, respectively, whereas the monoclonal antibody HB135, directed against an irrelevant CR2 epitope, had no effect. Blockade......Normal human B lymphocytes activate the alternative pathway of complement via complement receptor type 2 (CR2, CD21), that binds hydrolysed C3 (iC3) and thereby promotes the formation of a membrane-bound C3 convertase. We have investigated whether this might lead to the generation of a C5...... processes on CR2, indicate that MAC formation is a consequence of alternative pathway activation....

The Role of Complement Inhibition in Thrombotic Angiopathies and Antiphospholipid Syndrome

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Erkan, Doruk; Salmon, Jane E.

2016-01-01

Antiphospholipid syndrome (APS) is characterized by thrombosis (arterial, venous, small vessel) and/or pregnancy morbidity occurring in patients with persistently positive antiphospholipid antibodies (aPL). Catastrophic APS is the most severe form of the disease, characterized by multiple organ thromboses occurring in a short period and commonly associated with thrombotic microangiopathy (TMA). Similar to patients with complement regulatory gene mutations developing TMA, increased complement activation on endothelial cells plays a role in hypercoagulability in aPL-positive patients. In mouse models of APS, activation of the complement is required and interaction of complement (C) 5a with its receptor C5aR leads to aPL-induced inflammation, placental insufficiency, and thrombosis. Anti-C5 antibody and C5aR antagonist peptides prevent aPL-mediated pregnancy loss and thrombosis in these experimental models. Clinical studies of anti-C5 monoclonal antibody in aPL-positive patients are limited to a small number of case reports. Ongoing and future clinical studies of complement inhibitors will help determine the role of complement inhibition in the management of aPL-positive patients. PMID:27020721

In Situ complement activation and T-cell immunity in leprosy spectrum: An immunohistological study on leprosy lesional skin.

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Nawal Bahia El Idrissi

Full Text Available Mycobacterium leprae (M. leprae infection causes nerve damage and the condition worsens often during and long after treatment. Clearance of bacterial antigens including lipoarabinomannan (LAM during and after treatment in leprosy patients is slow. We previously demonstrated that M. leprae LAM damages peripheral nerves by in situ generation of the membrane attack complex (MAC. Investigating the role of complement activation in skin lesions of leprosy patients might provide insight into the dynamics of in situ immune reactivity and the destructive pathology of M. leprae. In this study, we analyzed in skin lesions of leprosy patients, whether M. leprae antigen LAM deposition correlates with the deposition of complement activation products MAC and C3d on nerves and cells in the surrounding tissue. Skin biopsies of paucibacillary (n = 7, multibacillary leprosy patients (n = 7, and patients with erythema nodosum leprosum (ENL (n = 6 or reversal reaction (RR (n = 4 and controls (n = 5 were analyzed. The percentage of C3d, MAC and LAM deposition was significantly higher in the skin biopsies of multibacillary compared to paucibacillary patients (p = <0.05, p = <0.001 and p = <0.001 respectively, with a significant association between LAM and C3d or MAC in the skin biopsies of leprosy patients (r = 0.9578, p< 0.0001 and r = 0.8585, p<0.0001 respectively. In skin lesions of multibacillary patients, MAC deposition was found on axons and co-localizing with LAM. In skin lesions of paucibacillary patients, we found C3d positive T-cells in and surrounding granulomas, but hardly any MAC deposition. In addition, MAC immunoreactivity was increased in both ENL and RR skin lesions compared to non-reactional leprosy patients (p = <0.01 and p = <0.01 respectively. The present findings demonstrate that complement is deposited in skin lesions of leprosy patients, suggesting that inflammation driven by complement activation might contribute to nerve damage in the lesions

Levels of occupational stress and stressful activities for nurses working in emergency

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José Ricardo Ferreira da Fonseca

2014-12-01

Full Text Available The study aimed to identify stress levels, areas and their activities identified as stressful by nurses working in the emergence in Manaus, AM, Brazil. It is an epidemiological, cross-sectional design, with 36 emergency nurses from December 2010 to January 2011. The Bianchi Stress Scale with 57 questions was used. The nurses were at risk for high levels of stress. The most stressful areas were the operation of the unit, conditions of work and personnel administration, and the most stressful activity was the request for equipment review and repair. The difference by Friedman test between the areas was significant (p <0.05, Dunn post-test significant (p <0.05 when compared by peers. The accumulation of management activities with the assistance activities can generate higher levels of stress, it is necessary to invest in improving the work environment and management support to minimize the stress experienced at work.

Complement-mediated neutralization of dengue virus requires mannose-binding lectin

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Avirutnan, Panisadee; Hauhart, Richard E; Marovich, Mary A

2011-01-01

-dependent activation of the complement cascade neutralized insect cell-derived West Nile virus (WNV) in cell culture and restricted pathogenesis in mice. Here, we investigated the antiviral activity of MBL in infection by dengue virus (DENV), a related flavivirus. Using a panel of naïve sera from mouse strains...... with lower levels. Our studies suggest that allelic variation of MBL in humans may impact complement-dependent control of DENV pathogenesis. IMPORTANCE Dengue virus (DENV) is a mosquito-transmitted virus that causes a spectrum of clinical disease in humans ranging from subclinical infection to dengue...... hemorrhagic fever and dengue shock syndrome. Four serotypes of DENV exist, and severe illness is usually associated with secondary infection by a different serotype. Here, we show that mannose-binding lectin (MBL), a pattern recognition molecule that initiates the lectin pathway of complement activation...

SALO, a novel classical pathway complement inhibitor from saliva of the sand fly Lutzomyia longipalpis.

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Ferreira, Viviana P; Fazito Vale, Vladimir; Pangburn, Michael K; Abdeladhim, Maha; Mendes-Sousa, Antonio Ferreira; Coutinho-Abreu, Iliano V; Rasouli, Manoochehr; Brandt, Elizabeth A; Meneses, Claudio; Lima, Kolyvan Ferreira; Nascimento Araújo, Ricardo; Pereira, Marcos Horácio; Kotsyfakis, Michalis; Oliveira, Fabiano; Kamhawi, Shaden; Ribeiro, Jose M C; Gontijo, Nelder F; Collin, Nicolas; Valenzuela, Jesus G

2016-01-13

Blood-feeding insects inject potent salivary components including complement inhibitors into their host's skin to acquire a blood meal. Sand fly saliva was shown to inhibit the classical pathway of complement; however, the molecular identity of the inhibitor remains unknown. Here, we identified SALO as the classical pathway complement inhibitor. SALO, an 11 kDa protein, has no homology to proteins of any other organism apart from New World sand flies. rSALO anti-complement activity has the same chromatographic properties as the Lu. longipalpis salivary gland homogenate (SGH)counterparts and anti-rSALO antibodies blocked the classical pathway complement activity of rSALO and SGH. Both rSALO and SGH inhibited C4b deposition and cleavage of C4. rSALO, however, did not inhibit the protease activity of C1s nor the enzymatic activity of factor Xa, uPA, thrombin, kallikrein, trypsin and plasmin. Importantly, rSALO did not inhibit the alternative or the lectin pathway of complement. In conclusion our data shows that SALO is a specific classical pathway complement inhibitor present in the saliva of Lu. longipalpis. Importantly, due to its small size and specificity, SALO may offer a therapeutic alternative for complement classical pathway-mediated pathogenic effects in human diseases.

Activation capacity of the alternative and classic complement pathways in patients operated on for colorectal cancer

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Zimmermann-Nielsen, Erik; Iversen, Lene H; Svehag, Sven-Erik

2002-01-01

surgery. The samples were analyzed with an enzyme-linked immunosorbent assay that measured C3 activation capacity by the alternative and classic complement pathways. Cancer patients were compared according to Dukes stage, type of surgery performed, transfusion of blood, development of infection, venous....... Significant differences in C3 activation capacities were observed between cancer patients that were related to Dukes stage and in patients with and without buffy coat-depleted red cells suspended in saline, adenine, glucose, and mannitol transfusion, infectious events, and deep venous thromboembolism...

Relationship between complement activation, cellular uptake and surface physicochemical aspects of novel PEG-modified nanocapsules.

Science.gov (United States)

Mosqueira, V C; Legrand, P; Gulik, A; Bourdon, O; Gref, R; Labarre, D; Barratt, G

2001-11-01

The aim of our work was to examine the relationship between modifications of the surface of nanocapsules (NC) by adsorption or covalent grafting of poly(ethylene oxide) (PEG), and changes in their phospholipid (PL) content on complement activation (C3 cleavage) and on uptake by macrophages. The physicochemical characterization of the NC included an investigation of their properties, such as surface charge, size, hydrophilicity, morphology and homogeneity. This is the first time that such properties have been correlated with biological interactions for NC, a novel carrier system with a structure more complex than nanospheres. C3 crossed immunoelectrophoresis revealed the reduced activation for NC with longer PEG chain and higher density, although all formulations induced C3 cleavage to a lesser or greater extent. NC bearing PEG covalently bound to the surface were weaker activators of complement than plain PLA [poly(D,L-lactide)] NC or nanospheres (NS). Furthermore, the fluorescent/confocal microscopy of J774A1 cells in contact with NC reveal a dramatically reduced interaction with PEG-bearing NC. However, the way in which PEG was attached (covalent or adsorbed) seemed to affect the mechanism of uptake. Taken together, these results suggest that the low level of protein binding to NC covered with a high density of 20kDa PEG chains is likely to be due to the steric barriers surrounding these particles, which prevents protein adsorption and reduces their interaction with macrophages.

Relationship between complement activation, cellular uptake and surface physicochemical aspects of novel PEG-modifed nanocapsules.

OpenAIRE

Mosqueira, Vanessa Carla Furtado; Legrand, Philippe; Gulik, Annette; Bourdon, Olivier; Gref, Ruxandra; Labarre, Denis; Barratt, Gillian

2001-01-01

ABSTRACT: The aim of our work was to examine the relationship between modi"cations of the surface of nanocapsules (NC) by adsorption or covalent grafting of poly(ethylene oxide) (PEG), and changes in their phospholipid (PL) content on complement activation (C3 cleavage) and on uptake by macrophages. The physicochemical characterization of the NC included an investigation of their properties, such as surface charge, size, hydrophilicity, morphology and homogeneity. This is the "rst ti...

Mechanisms of evasion of Schistosoma mansoni schistosomula to the lethal activity of complement

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F. Juarez Ramalho-Pinto

1992-01-01

Full Text Available Schistosomula of Schistosoma mansoni became resistant to antibody-dependent complement damage in vitro after pre-incubation with normal human erythrocytes (NHuE whatever the ABO or Rh blood group. Resistant parasites were shown to acquire host decay accelerating factor (DAF , a 70 kDa glycoprotein attached to the membrane of NHue by a GPI anchor. IgG2a mAb anti-human DAF (IA10 immunoprecipitated a 70 kDa molecule from 125I-labeled schistosomula pre-incubated with NHuE and inhibited their resistance to complement-dependent killing in vtro. Incubationof schistosomula with erytrocytes from patients with paroxsimal nocturnal hemoglobinuria (PNHE or SRBC, wich are DAF-deficient, did not protect the parasites from complement lesion. Supernatant of 100,000 x g collected from NHuE incubated for 24 h in defined medium was shown to contain a soluble form of DAF and to protect schistosomula from complement killing. Schistosomula treated with trypsin before incubation with NHuE ghosts did not become resistant to complement damage. On the other hand, pre-treatment with chymotrypsin did not interfere with the acquisition of resistance by the schistosomula. These results indicate that, in vitro, NHuE DAF can be transferred to schistosomula in a soluble form and that the binding of this molecule to the parasite surface is dependent upon trypsin-sensitive chymotrypsin-insensitive polipeptide(s present on the surface of the worm.

Deficiency of the complement regulator CD59a exacerbates Wallerian degeneration

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Ramaglia, Valeria; King, Rosalind Helen Mary; Morgan, Bryan Paul; Baas, Frank

2009-01-01

The complement system is implicated in Wallerian degeneration (WD). We have previously shown that the membrane attack complex (MAC) the terminal activation product of the complement cascade, mediates rapid axonal degradation and myelin clearance during WD after peripheral nerve injury. In this study

Genome Mining of the Marine Actinomycete Streptomyces sp. DUT11 and Discovery of Tunicamycins as Anti-complement Agents

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Xiao-Na Xu

2018-06-01

Full Text Available Marine actinobacteria are potential producers of various secondary metabolites with diverse bioactivities. Among various bioactive compounds, anti-complement agents have received great interest for drug discovery to treat numerous diseases caused by inappropriate activation of the human complement system. However, marine streptomycetes producing anti-complement agents are still poorly explored. In this study, a marine-derived strain Streptomyces sp. DUT11 showing superior anti-complement activity was focused, and its genome sequence was analyzed. Gene clusters showing high similarities to that of tunicamycin and nonactin were identified, and their corresponding metabolites were also detected. Subsequently, tunicamycin I, V, and VII were isolated from Streptomyces sp. DUT11. Anti-complement assay showed that tunicamycin I, V, VII inhibited complement activation through the classic pathway, whereas no anti-complement activity of nonactin was detected. This is the first time that tunicamycins are reported to have such activity. In addition, genome analysis indicates that Streptomyces sp. DUT11 has the potential to produce novel lassopeptides and lantibiotics. These results suggest that marine Streptomyces are rich sources of anti-complement agents for drug discovery.

Perioperative functional activity of the alternative pathway of complement in patients with colonic cancer

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Baatrup, G; Zimmermann-Nielsen, E; Qvist, N

1999-01-01

OBJECTIVE: To investigate the functional capacity of the alternative pathway of complement in patients with cancer of the colon before, during, and after operation. DESIGN: Prospective study. SETTING: One university and two district hospitals, Denmark. SUBJECTS: 28 patients having elective...... or emergency operations for colonic cancer. INTERVENTIONS: Measurements of C3b fixing capacity of the alternative complement pathway in serum before, during, and after operation. MAIN OUTCOME MEASUREMENTS: The functional capacity of the alternative pathway of complement, and changes during operation. RESULTS......: The functional capacity of the alternative pathway in patients with cancer of the colon was above normal (p

Human pentraxin 3 binds to the complement regulator c4b-binding protein.

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Anne Braunschweig

Full Text Available The long pentraxin 3 (PTX3 is a soluble recognition molecule with multiple functions including innate immune defense against certain microbes and the clearance of apoptotic cells. PTX3 interacts with recognition molecules of the classical and lectin complement pathways and thus initiates complement activation. In addition, binding of PTX3 to the alternative complement pathway regulator factor H was shown. Here, we show that PTX3 binds to the classical and lectin pathway regulator C4b-binding protein (C4BP. A PTX3-binding site was identified within short consensus repeats 1-3 of the C4BP α-chain. PTX3 did not interfere with the cofactor activity of C4BP in the fluid phase and C4BP maintained its complement regulatory activity when bound to PTX3 on surfaces. While C4BP and factor H did not compete for PTX3 binding, the interaction of C4BP with PTX3 was inhibited by C1q and by L-ficolin. PTX3 bound to human fibroblast- and endothelial cell-derived extracellular matrices and recruited functionally active C4BP to these surfaces. Whereas PTX3 enhanced the activation of the classical/lectin pathway and caused enhanced C3 deposition on extracellular matrix, deposition of terminal pathway components and the generation of the inflammatory mediator C5a were not increased. Furthermore, PTX3 enhanced the binding of C4BP to late apoptotic cells, which resulted in an increased rate of inactivation of cell surface bound C4b and a reduction in the deposition of C5b-9. Thus, in addition to complement activators, PTX3 interacts with complement inhibitors including C4BP. This balanced interaction on extracellular matrix and on apoptotic cells may prevent excessive local complement activation that would otherwise lead to inflammation and host tissue damage.

Stress-related disorders, pituitary adenylate cyclase-activating peptide (PACAP)ergic system, and sex differences.

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Ramikie, Teniel S; Ressler, Kerry J

2016-12-01

Trauma-related disorders, such as posttraumatic stress disorder (PTSD) are remarkably common and debilitating, and are often characterized by dysregulated threat responses. Across numerous epidemiological studies, females have been found to have an approximately twofold increased risk for PTSD and other stress-related disorders. Understanding the biological mechanisms of this differential risk is of critical importance. Recent data suggest that the pituitary adenylate cyclase-activating polypeptide (PACAP) pathway is a critical regulator of the stress response across species. Moreover, increasing evidence suggests that this pathway is regulated by both stress and estrogen modulation and may provide an important window into understanding mechanisms of sex differences in the stress response. We have recently shown that PACAP and its receptor (PAC1R) are critical mediators of abnormal processes after psychological trauma. Notably, in heavily traumatized human subjects, there appears to be a robust sex-specific association of PACAP blood levels and PAC1R gene variants with fear physiology, PTSD diagnosis, and symptoms, specifically in females. The sex-specific association occurs within a single-nucleotide polymorphism (rs2267735) that resides in a putative estrogen response element involved in PAC1R gene regulation. Complementing these human data, the PAC1R messenger RNA is induced with fear conditioning or estrogen replacement in rodent models. These data suggest that perturbations in the PACAP-PAC1R pathway are regulated by estrogen and are involved in abnormal fear responses underlying PTSD.

A systematic analysis of the complement pathways in patients with neuromyelitis optica indicates alteration but no activation during remission

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Veszeli, Nóra; Füst, György; Csuka, Dorottya

2014-01-01

Neuromyelitis optica (NMO) is an autoimmune demyelinating inflammatory disorder, mediated by pathogenic autoantibodies against aquaporin 4 (AQP4), the main water channel of the central nervous system (CNS). NMO is characterized by local IgG deposition and complement activation within the CNS...

Inhibition of the alternative complement activation pathway in traumatic brain injury by a monoclonal anti-factor B antibody: a randomized placebo-controlled study in mice

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Holers V Michael

2007-05-01

Full Text Available Abstract Background The posttraumatic response to traumatic brain injury (TBI is characterized, in part, by activation of the innate immune response, including the complement system. We have recently shown that mice devoid of a functional alternative pathway of complement activation (factor B-/- mice are protected from complement-mediated neuroinflammation and neuropathology after TBI. In the present study, we extrapolated this knowledge from studies in genetically engineered mice to a pharmacological approach using a monoclonal anti-factor B antibody. This neutralizing antibody represents a specific and potent inhibitor of the alternative complement pathway in mice. Methods A focal trauma was applied to the left hemisphere of C57BL/6 mice (n = 89 using a standardized electric weight-drop model. Animals were randomly assigned to two treatment groups: (1 Systemic injection of 1 mg monoclonal anti-factor B antibody (mAb 1379 in 400 μl phosphate-buffered saline (PBS at 1 hour and 24 hours after trauma; (2 Systemic injection of vehicle only (400 μl PBS, as placebo control, at identical time-points after trauma. Sham-operated and untreated mice served as additional negative controls. Evaluation of neurological scores and analysis of brain tissue specimens and serum samples was performed at defined time-points for up to 1 week. Complement activation in serum was assessed by zymosan assay and by murine C5a ELISA. Brain samples were analyzed by immunohistochemistry, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL histochemistry, and real-time RT-PCR. Results The mAb 1379 leads to a significant inhibition of alternative pathway complement activity and to significantly attenuated C5a levels in serum, as compared to head-injured placebo-treated control mice. TBI induced histomorphological signs of neuroinflammation and neuronal apoptosis in the injured brain hemisphere of placebo-treated control mice for up to 7 days. In contrast, the

The role of complement in CD4⁺ T cell homeostasis and effector functions.

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Kolev, Martin; Le Friec, Gaëlle; Kemper, Claudia

2013-02-01

The complement system is among the evolutionary oldest 'players' of the immune system. It was discovered in 1896 by Jules Bordet as a heat-labile fraction of the serum responsible for the opsonisation and subsequent killing of bacteria. The decades between the 1920s and 1990s then marked the discovery and biochemical characterization of the proteins comprising the complement system. Today, complement is defined as a complex system consisting of more than 30 membrane-bound and soluble plasma proteins, which are activated in a cascade-like manner, very similarly to the caspase proteases and blood coagulation systems. Complement is engrained in the immunologist's mind as a serum-effective, quintessential part of innate immunity, vitally required for the detection and removal of pathogens or other dangerous entities. Three decades ago, this rather confined definition was challenged and then refined when it was shown that complement participates vitally in the induction and regulation of B cell responses, thus adaptive immunity. Similarly, research work published in more recent years supports an equally important role for the complement system in shaping T cell responses. Today, we are again facing paradigm shifts in the field: complement is actively involved in the negative control of T cell effector immune responses, and thus, by definition in immune homeostasis. Further, while serum complement activity is without doubt fundamental in the defence against invading pathogens, local immune cell-derived production of complement emerges as key mediator of complement's impact on adaptive immune responses. And finally, the impact of complement on metabolic pathways and the crosstalk between complement and other immune effector systems is likely more extensive than previously anticipated and is fertile ground for future discoveries. In this review, we will discuss these emerging new roles of complement, with a focus on Th1 cell biology. Copyright © 2013 Elsevier Ltd. All

Complement activation by cholesterol crystals triggers a subsequent cytokine response

DEFF Research Database (Denmark)

Niyonzima, Nathalie; Halvorsen, Bente; Sporsheim, Bjørnar

2017-01-01

beneficial effects on atherosclerosis and a large clinical trial with an IL-1β inhibitor is currently in progress (the CANTOS study). However, upstream inhibition of CC-induced inflammation by using a complement inhibitor may be more efficient in treating atherosclerosis since this will block initiation...

High salt intake enhances swim stress-induced PVN vasopressin cell activation and active stress coping.

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Mitchell, N C; Gilman, T L; Daws, L C; Toney, G M

2018-07-01

Stress contributes to many psychiatric disorders; however, responsivity to stressors can vary depending on previous or current stress exposure. Relatively innocuous heterotypic (differing in type) stressors can summate to result in exaggerated neuronal and behavioral responses. Here we investigated the ability of prior high dietary sodium chloride (salt) intake, a dehydrating osmotic stressor, to enhance neuronal and behavioral responses of mice to an acute psychogenic swim stress (SS). Further, we evaluated the contribution of the osmo-regulatory stress-related neuropeptide arginine vasopressin (VP) in the hypothalamic paraventricular nucleus (PVN), one of only a few brain regions that synthesize VP. The purpose of this study was to determine the impact of high dietary salt intake on responsivity to heterotypic stress and the potential contribution of VPergic-mediated neuronal activity on high salt-induced stress modulation, thereby providing insight into how dietary (homeostatic) and environmental (psychogenic) stressors might interact to facilitate psychiatric disorder vulnerability. Salt loading (SL) with 4% saline for 7 days was used to dehydrate and osmotically stress mice prior to exposure to an acute SS. Fluid intake and hematological measurements were taken to quantify osmotic dehydration, and serum corticosterone levels were measured to index stress axis activation. Immunohistochemistry (IHC) was used to stain for the immediate early gene product c-Fos to quantify effects of SL on SS-induced activation of neurons in the PVN and extended amygdala - brain regions that are synaptically connected and implicated in responding to osmotic stress and in modulation of SS behavior, respectively. Lastly, the role of VPergic PVN neurons and VP type 1 receptor (V1R) activity in the amygdala in mediating effects of SL on SS behavior was evaluated by quantifying c-Fos activation of VPergic PVN neurons and, in functional experiments, by nano-injecting the V1R selective

Structural features and complement-fixing activity of pectin from three Brassica oleracea varieties: white cabbage, kale, and red kale.

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Samuelsen, Anne Berit; Westereng, Bjørge; Yousif, Osman; Holtekjølen, Ann Katrin; Michaelsen, Terje E; Knutsen, Svein H

2007-02-01

Leaves of different cabbage species are used both as food and as wound healing remedies in traditional medicine. This supposed wound healing activity might be connected to presence of immunomodulating water soluble polysaccharides. To study this, three different cabbage varieties, white cabbage (W), kale (K), and red kale (RK), were pretreated with 80% ethanol and then extracted with water at 50 degrees C and 100 degrees C for isolation of polysaccharide-containing fractions. The fractions were analyzed for monosaccharide composition, glycosidic linkages, Mw distribution, protein content, and phenolic compounds and then tested for complement-fixing activity. All fractions contained pectin type polysaccharides with linkages corresponding to homogalacturonan and hairy regions. Those extracted at 50 degrees C contained higher amounts of neutral side chains and were more active in the complement-fixation test than those extracted at 100 degrees C. The fractions can be ranged by decreasing activity: K-50 > RK-50 > W-50 approximately = K-100 > RK100 approximately = W-100. Studies on structure-activity relationships (SAR) employing multivariate statistical analysis strongly suggest that the magnitude of the measured activity is influenced by the content of certain side chains in the polymers. High activity correlates to large neutral side chains with high amounts of (1-->6)- and (1-->3,6)-linked Gal and low amounts of (1-->4)-linked GalA but not on molecular weight distribution of the polymers.

Complement activation-related pseudoallergy in dogs following intravenous administration of a liposomal formulation of meglumine antimoniate

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Raul R. Ribeiro

2013-08-01

Full Text Available The increasing use of nanotechnologies in advanced therapies has allowed the observation of specific adverse reactions related to nanostructures. The toxicity of a novel liposome formulation of meglumine antimoniate in dogs with visceral leishmaniasis after single dose has been investigated. Groups of 12 animals received by the intravenous route a single dose of liposomal meglumine antimoniate (group I [GI], 6.5 mg Sb/kg, empty liposomes (GII or isotonic saline (GIII. Evaluation of hematological and biochemical parameters showed no significant changes 4 days after administration. No undesired effects were registered in the GIII. However, adverse reactions were observed in 67.7% of dogs from both groups that received liposomal formulations. The side effects began moments after bolus administration and disappeared during the first 15 minutes after treatment. Prostation, sialorrhea and defecation were the most frequent clinical signs, registered in 33.3% and 41.6 % of animals from the groups GI and GII, respectively. Tachypnea, mydriasis, miosis, vomiting and cyanosis were also registered in both groups. The adverse reactions observed in this study were attributed to the activation of the complement system by lipid vesicles in a phenomenon known as Complement Activation-Related Pseudoallergy (CARPA. The influence of the physical-chemical characteristics of liposomal formulation in the triggering of CARPA is discussed.

Possible role of complement activation in renal impairment in trichloroethylene-sensitized guinea pigs

International Nuclear Information System (INIS)

Yu, Jun-Feng; Leng, Jing; Shen, Tong; Zhou, Cheng-Fan; Xu, Hui; Jiang, Tao; Xu, Shu-Hai; Zhu, Qi-Xing

2012-01-01

Recent studies have revealed that trichloroethylene (TCE) can induce occupational medicamentosa-like dermatitis (OMLD) with multi-system injuries, including liver, kidney and skin injuries, which can subsequently cause multiple organ failure later. But the mechanism of immune dysfunction leading to organ injury was rarely clarified. The present study was initiated to analyze the influence of trichloroethylene on renal injury and study the relevant mechanism in guinea pigs. Guinea pig maximization test (GPMT) was carried out. Inflammation on the guinea pigs’ skin was scored. Kidney function, urine protein and ultra-structural change of kidney were determined by biochemical detection and electron microscope. Deposition of complement 3 and membrane attack complex (MAC, C5b-9) were determined by immunohistochemistry. Erythema and edema of skin impairment were observed in TCE sensitized groups, and sensitization rate was 63.16%. Through electron microscope, tubular epithelial cell mitochondrial swelling, vacuolar degeneration and atrophy of microvillus were observed in TCE sensitized groups. The parameters of urease and urinary protein elevated markedly, and a high degree of C3 and MAC deposition was found in the renal tubular epithelial cells in TCE sensitized groups. By demonstrating that TCE and its metabolites can cause the deposition of C3 and MAC in renal epithelial cells, we found that activated complement system may be the mechanism of the acceleration and the development of TCE-induced kidney disease.

Lessons learned from mice deficient in lectin complement pathway molecules

DEFF Research Database (Denmark)

Genster, Ninette; Takahashi, Minoru; Sekine, Hideharu

2014-01-01

in turn activate downstream complement components, ultimately leading to elimination of the pathogen. Mice deficient in the key molecules of lectin pathway of complement have been generated in order to build knowledge of the molecular mechanisms of the lectin pathway in health and disease. Despite......The lectin pathway of the complement system is initiated when the pattern-recognition molecules, mannose-binding lectin (MBL), ficolins or collectin-11, bind to invading pathogens or damaged host cells. This leads to activation of MBL/ficolin/collectin-11 associated serine proteases (MASPs), which...... differences in the genetic arrangements of murine and human orthologues of lectin pathway molecules, the knockout mice have proven to be valuable models to explore the effect of deficiency states in humans. In addition, new insight and unexpected findings on the diverse roles of lectin pathway molecules...

Role of complement in porphyrin-induced photosensitivity

International Nuclear Information System (INIS)

Lim, H.W.; Gigli, I.

1981-01-01

Addition of porphyrins to sera of guinea pigs in vitro, followed by irradiation with 405 nm light, resulted in dose-dependent inhibitions of hemolytic activity of complement. With guinea pig as an animal model, we also found that systemically administered porphyrins, followed by irradiation with 405 nm light, resulted in dose-dependent inhibition of CH50 in vivo. The erythrocytes from porphyrin-treated guinea pigs showed an increased susceptibility to hemolysis induced by 405 nm irradiation in vitro. Clinical changes in these animals were limited to light-exposed areas and consisted of erythema, crusting, and delayed growth of hair. Histologically, dermal edema, dilation of blood vessels, and infiltration of mononuclear and polymorphonuclear cells were observed. Guinea pigs irradiated with ultraviolet-B developed erythema, but had no alteration of their complement profiles. It is suggested that complement products may play a specific role in the pathogenesis of the cutaneous lesions of some porphyrias

Excretion of complement proteins and its activation marker C5b-9 in IgA nephropathy in relation to renal function

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Onda Kisara

2011-11-01

Full Text Available Abstract Background Glomerular damage in IgA nephropathy (IgAN is mediated by complement activation via the alternative and lectin pathways. Therefore, we focused on molecules stabilizing and regulating the alternative pathway C3 convertase in urine which might be associated with IgAN pathogenesis. Methods Membrane attack complex (MAC, properdin (P, factor H (fH and Complement receptor type 1 (CR1 were quantified in urine samples from 71 patients with IgAN and 72 healthy controls. Glomerular deposition of C5, fH and P was assessed using an immunofluorescence technique and correlated with histological severity of IgAN and clinical parameters. Fibrotic changes and glomerular sclerosis were evaluated in renal biopsy specimens. Results Immunofluorescence studies revealed glomerular depositions of C5, fH and P in patients with IgAN. Urinary MAC, fH and P levels in IgAN patients were significantly higher than those in healthy controls (p Conclusions Complement activation occurs in the urinary space in IgAN and the measurement of levels of MAC and fH in the urine could be a useful indicator of renal injury in patients with IgAN.

The intestinal complement system in inflammatory bowel disease: Shaping intestinal barrier function.

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Sina, Christian; Kemper, Claudia; Derer, Stefanie

2018-06-01

The complement system is part of innate sensor and effector systems such as the Toll-like receptors (TLRs). It recognizes and quickly systemically and/or locally respond to microbial-associated molecular patterns (MAMPs) with a tailored defense reaction. MAMP recognition by intestinal epithelial cells (IECs) and appropriate immune responses are of major importance for the maintenance of intestinal barrier function. Enterocytes highly express various complement components that are suggested to be pivotal for proper IEC function. Appropriate activation of the intestinal complement system seems to play an important role in the resolution of chronic intestinal inflammation, while over-activation and/or dysregulation may worsen intestinal inflammation. Mice deficient for single complement components suffer from enhanced intestinal inflammation mimicking the phenotype of patients with chronic inflammatory bowel disease (IBD) such as Crohn's disease (CD) or ulcerative colitis (UC). However, the mechanisms leading to complement expression in IECs seem to differ markedly between UC and CD patients. Hence, how IECs, intestinal bacteria and epithelial cell expressed complement components interact in the course of IBD still remains to be mostly elucidated to define potential unique patterns contributing to the distinct subtypes of intestinal inflammation observed in CD and UC. Copyright © 2018 Elsevier Ltd. All rights reserved.

CR2-mediated activation of the complement alternative pathway results in formation of membrane attack complexes on human B lymphocytes

DEFF Research Database (Denmark)

Nielsen, C H; Marquart, H V; Prodinger, W M

2001-01-01

of the CR1 binding site with the monoclonal antibody 3D9 also resulted in a minor reduction in MAC deposition, while FE8 and 3D9, in combination, markedly reduced deposition of both C3 fragments (91 +/- 5%) and C9 (95 +/- 3%). The kinetics of C3-fragment and MAC deposition, as well as the dependence of both......Normal human B lymphocytes activate the alternative pathway of complement via complement receptor type 2 (CR2, CD21), that binds hydrolysed C3 (iC3) and thereby promotes the formation of a membrane-bound C3 convertase. We have investigated whether this might lead to the generation of a C5...... convertase and consequent formation of membrane attack complexes (MAC). Deposition of C3 fragments and MAC was assessed on human peripheral B lymphocytes in the presence of 30% autologous serum containing 4.4 mM MgCl2/20 mM EGTA, which abrogates the classical pathway of complement without affecting...

Effect of dietary γ-aminobutyric acid on laying performance, egg quality, immune activity and endocrine hormone in heat-stressed Roman hens.

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Zhang, Min; Zou, Xiao-Ting; Li, Hui; Dong, Xin-Yang; Zhao, Wenjing

2012-02-01

This study was conducted to evaluate the effect of γ-aminobutyric acid (GABA) on laying performance, egg quality, digestive enzyme activity, hormone level and immune activities in Roman hens under heat stress. Roman hens (320 days old) were fed with 0, 25, 50, 75 and 100 mg/kg GABA, respectively during a 60-day experiment. Compared with control, supplementation of 50 mg/kg GABA improved the laying performance and egg quality by significantly increasing egg production, average egg weight and shell strength (P level. Anti-oxidation activity was improved by significantly increasing the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), but decreasing malondialdehyde level in serum (P level, follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E(2) ), insulin, triiodothyronine (T(3) ) and free triiodothyronine (FT(3) ) levels, and IgG, IgA and complement (C3)activity in serum (P GABA improved laying performance and physical condition mainly by modulating hormone secretion, enhancing anti-oxidation and immune activity, and maintaining electrolyte balance. Fifty mg/kg was the optimum level for laying hens under heat stress in the present study. © 2011 The Authors. Animal Science Journal © 2011 Japanese Society of Animal Science.

The membrane attack complex of complement contributes to plasmin-induced synthesis of platelet-activating factor by endothelial cells and neutrophils.

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Lupia, Enrico; Del Sorbo, Lorenzo; Bergerone, Serena; Emanuelli, Giorgio; Camussi, Giovanni; Montrucchio, Giuseppe

2003-08-01

Thrombolytic agents, used to restore blood flow to ischaemic tissues, activate several enzymatic systems with pro-inflammatory effects, thus potentially contributing to the pathogenesis of ischaemia-reperfusion injury. Platelet-activating factor (PAF), a phospholipid mediator of inflammation, has been implicated in the pathogenesis of this process. We previously showed that the infusion of streptokinase (SK) induces the intravascular release of PAF in patients with acute myocardial infarction (AMI), and that cultured human endothelial cells (EC) synthesized PAF in response to SK and plasmin (PLN). In the present study, we investigated the role of the membrane attack complex (MAC) of complement in the PLN-induced synthesis of PAF. In vivo, we showed a correlation between the levels of soluble terminal complement components (sC5b-9) and the concentrations of PAF detected in blood of patients with AMI infused with SK. In vitro both EC and polymorphonuclear neutrophils (PMN), incubated in the presence of PLN and normal human serum, showed an intense staining for the MAC neoepitope, while no staining was detected when they were incubated with PLN in the presence of heat-inactivated normal human serum. Moreover, the insertion of MAC on EC and PMN plasmamembrane elicited the synthesis of PAF. In conclusion, our results elucidate the mechanisms involved in PAF production during the activation of the fibrinolytic system, showing a role for complement products in this setting. The release of PAF may increase the inflammatory response, thus limiting the beneficial effects of thrombolytic therapy. Moreover, it may have a pathogenic role in other pathological conditions, such as transplant rejection, tumoral angiogenesis, and septic shock, where fibrinolysis is activated.

CSF coccidioides complement fixation

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... this page: //medlineplus.gov/ency/article/003526.htm CSF coccidioides complement fixation test To use the sharing features on this page, please enable JavaScript. CSF coccidioides complement fixation is a test that checks ...

Cardiovascular Reactivity, Stress, and Physical Activity

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Chun-Jung eHuang

2013-11-01

Full Text Available Psychological stress has been proposed as a major contributor to the progression of cardiovascular disease (CVD. Acute mental stress can activate the sympathetic-adrenal-medullary (SAM axis, eliciting the release of catecholamines (NE and EPI resulting in the elevation of heart rate (HR and blood pressure (BP. Combined stress (psychological and physical can exacerbate these cardiovascular responses, which may partially contribute to the elevated risk of CVD and increased proportionate mortality risks experienced by some occupations (e.g., firefighting and law enforcement. Studies have supported the benefits of physical activity on physiological and psychological health, including the cardiovascular response to acute stress. Aerobically trained individuals exhibit lower sympathetic nervous system (e.g., HR reactivity and enhanced cardiovascular efficiency (e.g., lower vascular reactivity and decreased recovery time in response to physical and/or psychological stress. In addition, resistance training has been demonstrated to attenuate cardiovascular responses and improve mental health. This review will examine stress-induced cardiovascular reactivity and plausible explanations for how exercise training and physical fitness (aerobic and resistance exercise can attenuate cardiovascular responses to stress. This enhanced functionality may facilitate a reduction in the incidence of stroke and myocardial infarction. Finally, this review will also address the interaction of obesity and physical activity on cardiovascular reactivity and CVD.

Lectin complement pathway gene profile of the donor and recipient does not influence graft outcome after kidney transplantation.

NARCIS (Netherlands)

Damman, J.; Kok, J.L.; Snieder, H.; Leuvenink, H.G.; Goor, H. van; Hillebrands, J.L.; Dijk, M.C.R.F. van; Hepkema, B.G.; Reznichenko, A.; Born, J. van den; Borst, M.H. de; Bakker, S.J.; Navis, G.J.; Ploeg, R.J.; Seelen, M.A.

2012-01-01

In kidney transplantation, complement activation was found to be induced by donor brain death, renal ischemia-reperfusion injury and allograft rejection. There are three known pathways of complement activation: the classical, lectin and the alternative pathway. The lectin complement pathway can be

Deposition of mannose-binding lectin and ficolins and activation of the lectin pathway of complement on the surface of polyurethane tubing used for cardiopulmonary bypass.

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Eppa, Łukasz; Pągowska-Klimek, Izabela; Świerzko, Anna S; Moll, Maciej; Krajewski, Wojciech R; Cedzyński, Maciej

2018-04-01

The artificial surface used for cardiopulmonary bypass (CPB) is a crucial factor activating the complement system and thus contributing to the generation of a systemic inflammatory response. The activation of classical and alternative pathways on this artificial surface is well known. In contrast, lectin pathway (LP) activation has not been fully investigated, although noted during CPB in several studies. Moreover, we have recently proved the contribution of the LP to the generation of the systemic inflammatory response syndrome after pediatric cardiac surgery. The aim of this study was to assess LP-mediated complement activation on the surface of polyurethane CPB circuit tubing (noncoated Chalice ® ), used for CPB procedures in children with congenital heart disease. We found deposition of mannose-binding lectin, ficolin-1, -2, and -3 on the surface of unused tubing and on tubing used for CPB from a small minority of patients. Furthermore, we observed deposition of complement C4 activation products on tubing used for CPB and previously unused tubing after incubation with normal serum. The latter finding indicates LP activation in vitro on the polyurethane surface. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1202-1208, 2018. © 2017 Wiley Periodicals, Inc.

Intragenic complementation by the nifJ-coded protein of Klebsiella pneumoniae.

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Stacey, G; Zhu, J; Shah, V K; Shen, S C; Brill, W J

1982-01-01

A single mutation, nifC1005 (Jin et al. Sci. Sin. 23:108-118, 1980), located between nifH and nifJ in the nif cluster of Klebsiella pneumoniae, genetically complemented mutations in each of the 17 known nif genes. This suggested that the mutation is located in a new nif gene. We showed by complementation analyses that only 3 of 12 nifJ mutations tested were complemented by nifC1005. Nitrogenase activity in cell extracts of the mutant with nifC1005 as well as NifJ- mutants was stimulated by th...

Natural IgM antibodies that bind neoepitopes exposed as a result of spinal cord injury , drive secondary injury by activating complement.

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Narang, Aarti; Qiao, Fei; Atkinson, Carl; Zhu, Hong; Yang, Xiaofeng; Kulik, Liudmila; Holers, V Michael; Tomlinson, Stephen

2017-06-19

Natural IgM antibodies (Abs) function as innate immune sensors of injury via recognition of neoepitopes expressed on damaged cells, although how this recognition systems function following spinal cord injury (SCI) exposes various neoepitopes and their precise nature remains largely unknown. Here, we investigated the role of two natural IgM monoclonal Abs (mAbs), B4 and C2, that recognize post-ischemic neoepitopes following ischemia and reperfusion in other tissues. Identification of post-SCI expressed neoepitopes was examined using previously characterized monoclonal Abs (B4 and C2 mAbs). The role of post-SCI neoepitopes and their recognition by natural IgM Abs in propagating secondary injury was examined in Ab-deficient Rag1-/- or wild type C57BL/6 mice using Ab reconstitution experiments and neoepitope-targeted therapeutic studies, respectively. Administration of B4 or C2 mAb following murine SCI increased lesion size and worsened functional outcome in otherwise protected Ab-deficient Rag1-/- mice. Injury correlated with colocalized deposition of IgM and C3d in injured spinal cords from both mAb reconstituted Rag1-/- mice and untreated wild-type mice. Depletion of peritoneal B1 B cells, a source of natural Abs, reduced circulating levels of IgM with B4 (annexin-IV) and C2 (subset of phospholipids) reactivity, reduced IgM and complement deposition in the spinal cord, and protected against SCI. We therefore investigated whether the B4 neoepitope represents a therapeutic target for complement inhibition. B4-Crry, a fusion protein consisting of a single-chain Ab derived from B4 mAb, linked to the complement inhibitor Crry, significantly protected against SCI. B4-Crry exhibited a dual function in that it inhibited both the binding of pathogenic IgM and blocked complement activation in the spinal cord. This study identifies important neoepitopes expressed within the spinal cord after injury. These neoepitopes are recognized by clonally specific natural IgM Abs that

Neuroendocrine and oxidoreductive mechanisms of stress-induced cardiovascular diseases.

Science.gov (United States)

Pajović, S B; Radojcić, M B; Kanazir, D T

2008-01-01

The review concerns a number of basic molecular pathways that play a crucial role in perception, transmission, and modulation of the stress signals, and mediate the adaptation of the vital processes in the cardiovascular system (CVS). These highly complex systems for intracellular transfer of information include stress hormones and their receptors, stress-activated phosphoprotein kinases, stress-activated heat shock proteins, and antioxidant enzymes maintaining oxidoreductive homeostasis of the CVS. Failure to compensate for the deleterious effects of stress may result in the development of different pathophysiological states of the CVS, such as ischemia, hypertension, atherosclerosis and infarction. Stress-induced dysbalance in each of the CVS molecular signaling systems and their contribution to the CVS malfunctioning is reviewed. The general picture of the molecular mechanisms of the stress-induced pathophysiology in the CVS pointed out the importance of stress duration and intensity as etiological factors, and suggested that future studies should be complemented by the careful insights into the individual factors of susceptibility to stress, prophylactic effects of 'healthy' life styles and beneficial action of antioxidant-rich nutrition.

The Surface-Exposed Protein SntA Contributes to Complement Evasion in Zoonotic Streptococcus suis.

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Deng, Simin; Xu, Tong; Fang, Qiong; Yu, Lei; Zhu, Jiaqi; Chen, Long; Liu, Jiahui; Zhou, Rui

2018-01-01

Streptococcus suis is an emerging zoonotic pathogen causing streptococcal toxic shock like syndrome (STSLS), meningitis, septicemia, and even sudden death in human and pigs. Serious septicemia indicates this bacterium can evade the host complement surveillance. In our previous study, a functionally unknown protein SntA of S. suis has been identified as a heme-binding protein, and contributes to virulence in pigs. SntA can interact with the host antioxidant protein AOP2 and consequently inhibit its antioxidant activity. In the present study, SntA is identified as a cell wall anchored protein that functions as an important player in S. suis complement evasion. The C3 deposition and membrane attack complex (MAC) formation on the surface of sntA -deleted mutant strain Δ sntA are demonstrated to be significantly higher than the parental strain SC-19 and the complementary strain CΔ sntA . The abilities of anti-phagocytosis, survival in blood, and in vivo colonization of Δ sntA are obviously reduced. SntA can interact with C1q and inhibit hemolytic activity via the classical pathway. Complement activation assays reveal that SntA can also directly activate classical and lectin pathways, resulting in complement consumption. These two complement evasion strategies may be crucial for the pathogenesis of this zoonotic pathogen. Concerning that SntA is a bifunctional 2',3'-cyclic nucleotide 2'-phosphodiesterase/3'-nucleotidase in many species of Gram-positive bacteria, these complement evasion strategies may have common biological significance.

Dissociable effects of Sry and sex chromosome complement on activity, feeding and anxiety-related behaviours in mice.

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Kopsida, Eleni; Lynn, Phoebe M; Humby, Trevor; Wilkinson, Lawrence S; Davies, William

2013-01-01

Whilst gonadal hormones can substantially influence sexual differentiation of the brain, recent findings have suggested that sex-linked genes may also directly influence neurodevelopment. Here we used the well-established murine 'four core genotype' (FCG) model on a gonadally-intact, outbred genetic background to characterise the contribution of Sry-dependent effects (i.e. those arising from the expression of the Y-linked Sry gene in the brain, or from hormonal sequelae of gonadal Sry expression) and direct effects of sex-linked genes other than Sry ('sex chromosome complement' effects) to sexually dimorphic mouse behavioural phenotypes. Over a 24 hour period, XX and XY gonadally female mice (lacking Sry) exhibited greater horizontal locomotor activity and reduced food consumption per unit bodyweight than XX and XY gonadally male mice (possessing Sry); in two behavioural tests (the elevated plus and zero mazes) XX and XY gonadally female mice showed evidence for increased anxiety-related behaviours relative to XX and XY gonadally male mice. Exploratory correlational analyses indicated that these Sry-dependent effects could not be simply explained by brain expression of the gene, nor by circulating testosterone levels. We also noted a sex chromosome complement effect on food (but not water) consumption whereby XY mice consumed more over a 24hr period than XX mice, and a sex chromosome complement effect in a third test of anxiety-related behaviour, the light-dark box. The present data suggest that: i) the male-specific factor Sry may influence activity and feeding behaviours in mice, and ii) dissociable feeding and anxiety-related murine phenotypes may be differentially modulated by Sry and by other sex-linked genes. Our results may have relevance for understanding the molecular underpinnings of sexually dimorphic behavioural phenotypes in healthy men and women, and in individuals with abnormal sex chromosome constitutions.

Dissociable effects of Sry and sex chromosome complement on activity, feeding and anxiety-related behaviours in mice.

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Eleni Kopsida

Full Text Available Whilst gonadal hormones can substantially influence sexual differentiation of the brain, recent findings have suggested that sex-linked genes may also directly influence neurodevelopment. Here we used the well-established murine 'four core genotype' (FCG model on a gonadally-intact, outbred genetic background to characterise the contribution of Sry-dependent effects (i.e. those arising from the expression of the Y-linked Sry gene in the brain, or from hormonal sequelae of gonadal Sry expression and direct effects of sex-linked genes other than Sry ('sex chromosome complement' effects to sexually dimorphic mouse behavioural phenotypes. Over a 24 hour period, XX and XY gonadally female mice (lacking Sry exhibited greater horizontal locomotor activity and reduced food consumption per unit bodyweight than XX and XY gonadally male mice (possessing Sry; in two behavioural tests (the elevated plus and zero mazes XX and XY gonadally female mice showed evidence for increased anxiety-related behaviours relative to XX and XY gonadally male mice. Exploratory correlational analyses indicated that these Sry-dependent effects could not be simply explained by brain expression of the gene, nor by circulating testosterone levels. We also noted a sex chromosome complement effect on food (but not water consumption whereby XY mice consumed more over a 24hr period than XX mice, and a sex chromosome complement effect in a third test of anxiety-related behaviour, the light-dark box. The present data suggest that: i the male-specific factor Sry may influence activity and feeding behaviours in mice, and ii dissociable feeding and anxiety-related murine phenotypes may be differentially modulated by Sry and by other sex-linked genes. Our results may have relevance for understanding the molecular underpinnings of sexually dimorphic behavioural phenotypes in healthy men and women, and in individuals with abnormal sex chromosome constitutions.

Foetal Ureaplasma parvum bacteraemia as a function of gestation-dependent complement insufficiency: Evidence from a sheep model of pregnancy.

Science.gov (United States)

Kemp, Matthew W; Ahmed, Shatha; Beeton, Michael L; Payne, Matthew S; Saito, Masatoshi; Miura, Yuichiro; Usuda, Haruo; Kallapur, Suhas G; Kramer, Boris W; Stock, Sarah J; Jobe, Alan H; Newnham, John P; Spiller, Owen B

2017-01-01

Complement is a central defence against sepsis, and increasing complement insufficiency in neonates of greater prematurity may predispose to increased sepsis. Ureaplasma spp. are the most frequently cultured bacteria from preterm blood samples. A sheep model of intrauterine Ureaplasma parvum infection was used to examine in vivo Ureaplasma bacteraemia at early and late gestational ages. Complement function and Ureaplasma killing assays were used to determine the correlation between complement potency and bactericidal activity of sera ex vivo. Ureaplasma was cultured from 50% of 95-day gestation lamb cord blood samples compared to 10% of 125-day gestation lambs. Bactericidal activity increased with increased gestational age, and a direct correlation between functional complement activity and bactericidal activity (R 2 =.86; PUreaplasma bacteraemia in vivo was confined to early preterm lambs with low complement function, but Ureaplasma infection itself did not diminish complement levels. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Complement factor H family proteins in their non-canonical role as modulators of cellular functions.

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Józsi, Mihály; Schneider, Andrea E; Kárpáti, Éva; Sándor, Noémi

2018-01-04

Complement factor H is a major regulator of the alternative pathway of the complement system. The factor H-related proteins are less characterized, but recent data indicate that they rather promote complement activation. These proteins have some common ligands with factor H and have both overlapping and distinct functions depending on domain composition and the degree of conservation of amino acid sequence. Factor H and some of the factor H-related proteins also appear in a non-canonical function that is beyond their role in the modulation of complement activation. This review covers our current understanding on this emerging role of factor H family proteins in modulating the activation and function of various cells by binding to receptors or receptor ligands. Copyright © 2018 Elsevier Ltd. All rights reserved.

Human antibodies fix complement to inhibit Plasmodium falciparum invasion of erythrocytes and are associated with protection against malaria.

Science.gov (United States)

Boyle, Michelle J; Reiling, Linda; Feng, Gaoqian; Langer, Christine; Osier, Faith H; Aspeling-Jones, Harvey; Cheng, Yik Sheng; Stubbs, Janine; Tetteh, Kevin K A; Conway, David J; McCarthy, James S; Muller, Ivo; Marsh, Kevin; Anders, Robin F; Beeson, James G

2015-03-17

Antibodies play major roles in immunity to malaria; however, a limited understanding of mechanisms mediating protection is a major barrier to vaccine development. We have demonstrated that acquired human anti-malarial antibodies promote complement deposition on the merozoite to mediate inhibition of erythrocyte invasion through C1q fixation and activation of the classical complement pathway. Antibody-mediated complement-dependent (Ab-C') inhibition was the predominant invasion-inhibitory activity of human antibodies; most antibodies were non-inhibitory without complement. Inhibitory activity was mediated predominately via C1q fixation, and merozoite surface proteins 1 and 2 were identified as major targets. Complement fixation by antibodies was very strongly associated with protection from both clinical malaria and high-density parasitemia in a prospective longitudinal study of children. Ab-C' inhibitory activity could be induced by human immunization with a candidate merozoite surface-protein vaccine. Our findings demonstrate that human anti-malarial antibodies have evolved to function by fixing complement for potent invasion-inhibitory activity and protective immunity. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Complement modulation of T cell immune responses during homeostasis and disease.

Science.gov (United States)

Clarke, Elizabeth V; Tenner, Andrea J

2014-11-01

The complement system is an ancient and critical effector mechanism of the innate immune system as it senses, kills, and clears infectious and/or dangerous particles and alerts the immune system to the presence of the infection and/or danger. Interestingly, an increasing number of reports have demonstrated a clear role for complement in the adaptive immune system as well. Of note, a number of recent studies have identified previously unknown roles for complement proteins, receptors, and regulators in T cell function. Here, we will review recent data demonstrating the influence of complement proteins C1q, C3b/iC3b, C3a (and C3aR), and C5a (and C5aR) and complement regulators DAF (CD55) and CD46 (MCP) on T cell function during homeostasis and disease. Although new concepts are beginning to emerge in the field of complement regulation of T cell function, future experiments should focus on whether complement is interacting directly with the T cell or is having an indirect effect on T cell function via APCs, the cytokine milieu, or downstream complement activation products. Importantly, the identification of the pivotal molecular pathways in the human systems will be beneficial in the translation of concepts derived from model systems to therapeutic targeting for treatment of human disorders. © 2014 Society for Leukocyte Biology.

Complement fixation test to C burnetii

Science.gov (United States)

... complement fixation test; Coxiella burnetii - complement fixation test; C burnetii - complement fixation test ... a specific foreign substance ( antigen ), in this case, C burnetii . Antibodies defend the body against bacteria, viruses, ...

Subversion of complement by hematophagous parasites.

Science.gov (United States)

Schroeder, Hélène; Skelly, Patrick J; Zipfel, Peter F; Losson, Bertrand; Vanderplasschen, Alain

2009-01-01

The complement system is a crucial part of innate and adaptive immunity which exerts a significant evolutionary pressure on pathogens. It has selected for those pathogens, mainly microorganisms but also parasites, that have evolved countermeasures. The characterization of how pathogens evade complement attack is a rapidly developing field of current research. In recent years, multiple complement evasion strategies have been characterized. In this review, we focus on complement escape mechanisms expressed by hematophagous parasites, a heterogeneous group of metazoan parasites that share the property of ingesting the whole blood of their host. Complement inhibition is crucial for parasite survival within the host tissue or to facilitate blood feeding. Finally, complement inhibition by hematophagous parasites may also contribute to their success as pathogen vectors.

Noun complement clauses as referential modifiers

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Carlos de Cuba

2017-01-01

Full Text Available A number of recent analyses propose that so-called noun complement clauses should be analyzed as a type of relative clause. In this paper, I present a number of complications for any analysis that equates noun complement clauses to relative clauses, and conclude that this type of analysis is on the wrong track. I present cross-linguistic evidence showing that the syntactic behavior of noun complement clauses does not pattern with relative clauses. Patterns of complementizer choice and complementizer drop as well as patterns involving main clause phenomena and extraction differ in the two constructions, which I argue is unexpected under a relative clause analysis that involves operator movement. Instead I present an alternative analysis in which I propose that the referentiality of a noun complement clause is linked to its syntactic behavior. Following recent work, I claim that referential clauses have a syntactically truncated left-periphery, and this truncation can account for the lack of main clause phenomena in noun complement clauses. I argue that the truncation analysis is also able to accommodate complementizer data patterns more easily than relative clause analyses that appeal to operator movement.

Mutations in complement regulatory proteins predispose to preeclampsia: a genetic analysis of the PROMISSE cohort.

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Jane E Salmon

2011-03-01

Full Text Available Pregnancy in women with systemic lupus erythematosus (SLE or antiphospholipid antibodies (APL Ab--autoimmune conditions characterized by complement-mediated injury--is associated with increased risk of preeclampsia and miscarriage. Our previous studies in mice indicate that complement activation targeted to the placenta drives angiogenic imbalance and placental insufficiency.We use PROMISSE, a prospective study of 250 pregnant patients with SLE and/or APL Ab, to test the hypothesis in humans that impaired capacity to limit complement activation predisposes to preeclampsia. We sequenced genes encoding three complement regulatory proteins--membrane cofactor protein (MCP, complement factor I (CFI, and complement factor H (CFH--in 40 patients who had preeclampsia and found heterozygous mutations in seven (18%. Five of these patients had risk variants in MCP or CFI that were previously identified in atypical hemolytic uremic syndrome, a disease characterized by endothelial damage. One had a novel mutation in MCP that impairs regulation of C4b. These findings constitute, to our knowledge, the first genetic defects associated with preeclampsia in SLE and/or APL Ab. We confirmed the association of hypomorphic variants of MCP and CFI in a cohort of non-autoimmune preeclampsia patients in which five of 59 were heterozygous for mutations.The presence of risk variants in complement regulatory proteins in patients with SLE and/or APL Ab who develop preeclampsia, as well as in preeclampsia patients lacking autoimmune disease, links complement activation to disease pathogenesis and suggests new targets for treatment of this important public health problem.ClinicalTrials.gov NCT00198068.

Intratracheally instilled titanium dioxide nanoparticles translocate to heart and liver and activate complement cascade in the heart of C57BL/6 mice

DEFF Research Database (Denmark)

Husain, Mainul; Wu, Dongmei; Saber, Anne T.

2015-01-01

translocation from the lungs. Adult female C57BL/6 mice were exposed via intratracheal instillation to 18 or 162 mu g of industrially relevant titanium dioxide nanoparticles (nano-TiO2) alongside vehicle controls. Using the nano-scale hyperspectral microscope, translocation to heart and liver was confirmed...... of translocation are unclear. We employed a nano-scale hyperspectral microscope to spatially observe and spectrally profile NPs in tissues and blood following pulmonary deposition in mice. In addition, we characterized effects occurring in blood, liver and heart at the mRNA and protein level following...... at both doses, and to blood at the highest dose, in mice analyzed 24 h post-exposure. Global gene expression profiling and ELISA analysis revealed activation of complement cascade and inflammatory processes in heart and specific activation of complement factor 3 in blood, suggesting activation of an early...

Human factor H-related protein 2 (CFHR2 regulates complement activation.

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Hannes U Eberhardt

Full Text Available Mutations and deletions within the human CFHR gene cluster on chromosome 1 are associated with diseases, such as dense deposit disease, CFHR nephropathy or age-related macular degeneration. Resulting mutant CFHR proteins can affect complement regulation. Here we identify human CFHR2 as a novel alternative pathway complement regulator that inhibits the C3 alternative pathway convertase and terminal pathway assembly. CFHR2 is composed of four short consensus repeat domains (SCRs. Two CFHR2 molecules form a dimer through their N-terminal SCRs, and each of the two C-terminal ends can bind C3b. C3b bound CFHR2 still allows C3 convertase formation but the CFHR2 bound convertases do not cleave the substrate C3. Interestingly CFHR2 hardly competes off factor H from C3b. Thus CFHR2 likely acts in concert with factor H, as CFHR2 inhibits convertases while simultaneously allowing factor H assisted degradation by factor I.

Subversion of complement by hematophagous parasites

OpenAIRE

Schroeder, Hélène; Skelly, Patrick; Zipfel, Peter F.; Losson, Bertrand; Vanderplasschen, Alain

2009-01-01

The complement system is a crucial part of innate and adaptive immunity which exerts a significant evolutionary pressure on pathogens. It has selected for those pathogens, mainly micro-organisms but also parasites, that have evolved countermeasures. The characterization of how pathogens evade complement attack is a rapidly developing field of current research. In recent years, multiple complement evasion strategies have been characterized. In this review, we focus on complement escape mechani...

How regional non-proliferation arrangements complement international verification

International Nuclear Information System (INIS)

Carlson, J.

1999-01-01

This presentation focuses on international verification in the form of IAEA Safeguards, and discusses the relationship between IAEA safeguards and the relevant regional arrangements, both the existing and the future. For most States the political commitment against acquisition of nuclear weapons has been carefully reached and strongly held. Their observance of treaty commitments does not depend on the deterrent effect of verification activities. Safeguards serve to assist States who recognise it is in their own interest to demonstrate their compliance to others. Thus safeguards are a vital confidence building measure in their own right, as well as being a major complement to the broader range of international confidence building measures. Safeguards can both complement other confidence building measures and in turn be complemented by them. Within consideration of how it could work it is useful to consider briefly current developments of IAEA safeguards, i.e. existing regional arrangements and nuclear weapon free zones

Functional analysis of atfA gene to stress response in pathogenic thermal dimorphic fungus Penicillium marneffei.

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Panjaphorn Nimmanee

Full Text Available Penicillium marneffei, the pathogenic thermal dimorphic fungus is a causative agent of a fatal systemic disease, penicilliosis marneffei, in immunocompromised patients especially HIV patients. For growth and survival, this fungus has to adapt to environmental stresses outside and inside host cells and this adaptation requires stress signaling pathways and regulation of gene expression under various kinds of stresses. In this report, P. marneffei activating transcription factor (atfA gene encoding bZip-type transcription factor was characterized. To determine functions of this gene, atfA isogenic mutant strain was constructed using the modified split marker recombination method. The phenotypes and susceptibility to varieties of stresses including osmotic, oxidative, heat, UV, cell wall and cell membrane stresses of the mutant strain were compared with the wild type and the atfA complemented strains. Results demonstrated that the mRNA expression level of P. marneffei atfA gene increased under heat stress at 42°C. The atfA mutant was more sensitive to sodium dodecyl sulphate, amphotericin B and tert-butyl hydroperoxide than the wild type and complemented strains but not hydrogen peroxide, menadione, NaCl, sorbitol, calcofluor white, itraconazole, UV stresses and heat stress at 39°C. In addition, recovery of atfA mutant conidia after mouse and human macrophage infections was significantly decreased compared to those of wild type and complemented strains. These results indicated that the atfA gene was required by P. marneffei under specific stress conditions and might be necessary for fighting against host immune cells during the initiation of infection.

The down-stream effects of mannan-induced lectin complement pathway activation depend quantitatively on alternative pathway amplification

DEFF Research Database (Denmark)

Harboe, Morten; Garred, Peter; Karlstrøm, Ellen

2009-01-01

Complement activation plays an important role in human pathophysiology. The effect of classical pathway activation is largely dependent on alternative pathway (AP) amplification, whereas the role of AP for the down-stream effect of mannan-induced lectin pathway (LP) activation is poorly understood...... that AP amplification is quantitatively responsible for the final effect of initial specific LP activation. TCC generation on the solid phase was distinctly but less inhibited by anti-fD. C2 bypass of the LP pathway could be demonstrated, and AP amplification was also essential during C2 bypass in LP...... as shown by complete inhibition of TCC generation in C2-deficient serum by anti-fD and anti-properdin antibodies. In conclusion, the down-stream effect of LP activation depends strongly on AP amplification in normal human serum and in the C2 bypass pathway....

The complement system: a gateway to gene-environment interactions in schizophrenia pathogenesis.

Science.gov (United States)

Nimgaonkar, V L; Prasad, K M; Chowdari, K V; Severance, E G; Yolken, R H

2017-11-01

The pathogenesis of schizophrenia is considered to be multi-factorial, with likely gene-environment interactions (GEI). Genetic and environmental risk factors are being identified with increasing frequency, yet their very number vastly increases the scope of possible GEI, making it difficult to identify them with certainty. Accumulating evidence suggests a dysregulated complement pathway among the pathogenic processes of schizophrenia. The complement pathway mediates innate and acquired immunity, and its activation drives the removal of damaged cells, autoantigens and environmentally derived antigens. Abnormalities in complement functions occur in many infectious and autoimmune disorders that have been linked to schizophrenia. Many older reports indicate altered serum complement activity in schizophrenia, though the data are inconclusive. Compellingly, recent genome-wide association studies suggest repeat polymorphisms incorporating the complement 4A (C4A) and 4B (C4B) genes as risk factors for schizophrenia. The C4A/C4B genetic associations have re-ignited interest not only in inflammation-related models for schizophrenia pathogenesis, but also in neurodevelopmental theories, because rodent models indicate a role for complement proteins in synaptic pruning and neurodevelopment. Thus, the complement system could be used as one of the 'staging posts' for a variety of focused studies of schizophrenia pathogenesis. They include GEI studies of the C4A/C4B repeat polymorphisms in relation to inflammation-related or infectious processes, animal model studies and tests of hypotheses linked to autoimmune diseases that can co-segregate with schizophrenia. If they can be replicated, such studies would vastly improve our understanding of pathogenic processes in schizophrenia through GEI analyses and open new avenues for therapy.

Treatment of platelets with riboflavin and ultraviolet light mediates complement activation and suppresses monocyte interleukin-12 production in whole blood.

Science.gov (United States)

Loh, Y S; Dean, M M; Johnson, L; Marks, D C

2015-11-01

Pathogen inactivation (PI) and storage may alter the immunomodulatory capacity of platelets (PLTs). The aim of this study was to examine the effect of PI (Riboflavin and ultraviolet light treatment) and storage on the capacity of PLTs to induce cytokine responses in recipient inflammatory cells. A pool and split design was used to prepare untreated and PI-treated buffy coat-derived platelet concentrates (PCs). Samples were taken on days 2 and 7 postcollection and incubated with ABO/RhD-matched fresh whole blood for 6 h with or without lipopolysaccharide (LPS). The intracellular production of IP-10, MCP-1, MIP-1α, IL-8, IL-6, IL-10, IL-12, TNF-α and MIP-1β in monocytes and neutrophils was assessed using flow cytometry. Complement proteins in PLT supernatants were measured using a cytometric bead array. PLTs and PLT supernatant (both untreated and PI-treated) resulted in modulation of intracellular MIP-1β and IL-12 production in monocytes. Compared to untreated PLTs, PI-treated PLTs resulted in significantly lower LPS-induced monocyte IL-12 production (day 7). The concentration of C3a and C5a (and their desArg forms) was significantly increased in PLT supernatants following PI. PI results in decreased LPS-induced monocyte IL-12 production and increased complement activation. The association between platelet-induced complement activation and IL-12 production warrants further investigation. © 2015 International Society of Blood Transfusion.

Cross-species complementation of bacterial- and eukaryotic-type cardiolipin synthases

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Petra Gottier

2017-11-01

Full Text Available The glycerophospholipid cardiolipin is a unique constituent of bacterial and mitochondrial membranes. It is involved in forming and stabilizing high molecular mass membrane protein complexes and in maintaining membrane architecture. Absence of cardiolipin leads to reduced efficiency of the electron transport chain, decreased membrane potential, and, ultimately, impaired respiratory metabolism. For the protozoan parasite Trypanosoma brucei cardiolipin synthesis is essential for survival, indicating that the enzymes involved in cardiolipin production represent potential drug targets. T. brucei cardiolipin synthase (TbCLS is unique as it belongs to the family of phospholipases D (PLD, harboring a prokaryotic-type cardiolipin synthase (CLS active site domain. In contrast, most other eukaryotic CLS, including the yeast ortholog ScCrd1, are members of the CDP-alcohol phosphatidyl­ transferase family. To study if these mechanistically distinct CLS enzymes are able to catalyze cardiolipin production in a cell that normally expresses a different type of CLS, we expressed TbCLS and ScCrd1 in CLS-deficient yeast and trypanosome strains, respectively. Our results show that TbCLS complemented cardiolipin production in CRD1 knockout yeast and partly restored wild-type colony forming capability under stress conditions. Remarkably, CL remodeling appeared to be impaired in the transgenic construct, suggesting that CL production and remodeling are tightly coupled processes that may require a clustering of the involved proteins into specific CL-synthesizing domains. In contrast, no complementation was observed by heterologous expression of ScCrd1 in conditional TbCLS knockout trypanosomes, despite proper mitochondrial targeting of the protein.

SALO, a novel classical pathway complement inhibitor from saliva of the sand fly Lutzomyia longipalpis

OpenAIRE

Viviana P. Ferreira; Vladimir Fazito Vale; Michael K. Pangburn; Maha Abdeladhim; Antonio Ferreira Mendes-Sousa; Iliano V. Coutinho-Abreu; Manoochehr Rasouli; Elizabeth A. Brandt; Claudio Meneses; Kolyvan Ferreira Lima; Ricardo Nascimento Araújo; Marcos Horácio Pereira; Michalis Kotsyfakis; Fabiano Oliveira; Shaden Kamhawi

2016-01-01

Blood-feeding insects inject potent salivary components including complement inhibitors into their host's skin to acquire a blood meal. Sand fly saliva was shown to inhibit the classical pathway of complement; however, the molecular identity of the inhibitor remains unknown. Here, we identified SALO as the classical pathway complement inhibitor. SALO, an 11 kDa protein, has no homology to proteins of any other organism apart from New World sand flies. rSALO anti-complement activity has the sa...

Age-Related Macular Degeneration: A Connection between Human Herpes Virus-6A-Induced CD46 Downregulation and Complement Activation?

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Walter Fierz

2017-10-01

Full Text Available Viruses are able to interfere with the immune system by docking to receptors on host cells that are important for proper functioning of the immune system. A well-known example is the human immunodeficiency virus that uses CD4 cell surface molecules to enter host lymphocytes and thereby deleteriously destroying the helper cell population of the immune system. A more complicated mechanism is seen in multiple sclerosis (MS where human herpes virus-6A (HHV-6A infects astrocytes by docking to the CD46 surface receptor. Such HHV-6A infection in the brain of MS patients has recently been postulated to enable Epstein–Barr virus (EBV to transform latently infected B-lymphocytes in brain lesions leading to the well-known phenomenon of oligoclonal immunoglobulin production that is widely used in the diagnosis of MS. The cellular immune response to HHV-6A and EBV is one part of the pathogenic mechanisms in MS. A more subtle pathogenic mechanism can be seen in the downregulation of CD46 on astrocytes by the infecting HHV-6A. Since CD46 is central in regulating the complement system, a lack of CD46 can lead to hyperactivation of the complement system. In fact, activation of the complement system in brain lesions is a well-known pathogenic mechanism in MS. In this review, it is postulated that a similar mechanism is central in the development of age-related macular degeneration (AMD. One of the earliest changes in the retina of AMD patients is the loss of CD46 expression in the retinal pigment epithelial (RPE cells in the course of geographic atrophy. Furthermore, CD46 deficient mice spontaneously develop dry-type AMD-like changes in their retina. It is also well known that certain genetic polymorphisms in the complement-inhibiting pathways correlate with higher risks of AMD development. The tenet is that HHV-6A infection of the retina leads to downregulation of CD46 and consequently to hyperactivation of the complement system in the eyes of susceptible

Radioimmunoelectrophoresis, a sensitive method for detecting cleavage of the fifth component of human complement (C5)

International Nuclear Information System (INIS)

Perez, H.D.; Ong, R.; Banda, D.; Goldstein, I.M.

1983-01-01

A method has been developed for detecting cleavage of human C5 in serum and whole blood as a consequence of complement activation. Standard, single-dimension immunoelectrophoresis was performed using as antibody a radioiodinated IgG fraction prepared from a commercially available antiserum to human C5. Autoradiographs developed after radioimmunoelectrophoresis of either normal human serum or functionally pure human C5 revealed only one precipitin band. In contrast, when either zymosan-treated serum or trypsin-treated human C5 were examined with this technique, two additional precipitin bands were detected. One migrated more anodally than native C5 while the other remained at the origin (cathode). Radioimmunoelectrophoresis was significantly more sensitive as an indicator of complement activation in human serum than either measurements of total hemolytic complement or a standard assay for complement (C5)-derived chemotactic activity. (Auth.)

Preparation of Low Molecular Weight Chondroitin Sulfates, Screening of a High Anti-Complement Capacity of Low Molecular Weight Chondroitin Sulfate and Its Biological Activity Studies in Attenuating Osteoarthritis.

Science.gov (United States)

Li, Lian; Li, Yan; Feng, Danyang; Xu, Linghua; Yin, Fengxin; Zang, Hengchang; Liu, Chunhui; Wang, Fengshan

2016-10-11

Chondroitin sulfate (CS) plays important roles in the complement system. However, the CS structure is complicated due to different sources and the number and positions of sulfate groups. The objective of this study was to prepare different low molecular weight chondroitin sulfates (LMWCSs) and to investigate the biological activity in anti-complement capacity. A series of LMWCSs was prepared from different sources and characterized by ultraviolet-visible (UV) spectroscopy, high-performance liquid chromatography (HPLC), size exclusion chromatography-multiangle laser light scattering (SEC-MALLS) and nuclear magnetic resonance (NMR) spectroscopy. Hemolytic, anti-complement 3 deposition capacity and cell viability assays were carried out to investigate the biological activities in vitro. The results showed that LMWCS prepared from shark cartilage with the oxidative degradation method (LMWCS-S-O) had the best anti-complement capacity. LMWCS-S-O could inhibit the alternative pathway of the complement system and protect chondrocytes from cell death. The attenuating effect of LMWCS-S-O on Osteoarthritis (OA) was investigated by destabilization of the medial meniscus (DMM) model in vivo. Functional wind-up, histological and C5b-9 analyses were used to evaluate the treatment effect on the OA model. In vivo results showed that LMWCS-S-O could attenuate OA. LMWCS-S-O with a high content of ΔDi-2,6diS and ΔDi-6S could be used for attenuating OA through regulating the complement system.

Preparation of Low Molecular Weight Chondroitin Sulfates, Screening of a High Anti-Complement Capacity of Low Molecular Weight Chondroitin Sulfate and Its Biological Activity Studies in Attenuating Osteoarthritis

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Lian Li

2016-10-01

Full Text Available Chondroitin sulfate (CS plays important roles in the complement system. However, the CS structure is complicated due to different sources and the number and positions of sulfate groups. The objective of this study was to prepare different low molecular weight chondroitin sulfates (LMWCSs and to investigate the biological activity in anti-complement capacity. A series of LMWCSs was prepared from different sources and characterized by ultraviolet-visible (UV spectroscopy, high-performance liquid chromatography (HPLC, size exclusion chromatography-multiangle laser light scattering (SEC-MALLS and nuclear magnetic resonance (NMR spectroscopy. Hemolytic, anti-complement 3 deposition capacity and cell viability assays were carried out to investigate the biological activities in vitro. The results showed that LMWCS prepared from shark cartilage with the oxidative degradation method (LMWCS-S-O had the best anti-complement capacity. LMWCS-S-O could inhibit the alternative pathway of the complement system and protect chondrocytes from cell death. The attenuating effect of LMWCS-S-O on Osteoarthritis (OA was investigated by destabilization of the medial meniscus (DMM model in vivo. Functional wind-up, histological and C5b-9 analyses were used to evaluate the treatment effect on the OA model. In vivo results showed that LMWCS-S-O could attenuate OA. LMWCS-S-O with a high content of ΔDi-2,6diS and ΔDi-6S could be used for attenuating OA through regulating the complement system.

Interactions between stress and physical activity on Alzheimer's disease pathology

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Carla M. Yuede

2018-02-01

Full Text Available Physical activity and stress are both environmental modifiers of Alzheimer's disease (AD risk. Animal studies of physical activity in AD models have largely reported positive results, however benefits are not always observed in either cognitive or pathological outcomes and inconsistencies among findings remain. Studies using forced exercise may increase stress and mitigate some of the benefit of physical activity in AD models, while voluntary exercise regimens may not achieve optimal intensity to provide robust benefit. We evaluated the findings of studies of voluntary and forced exercise regimens in AD mouse models to determine the influence of stress, or the intensity of exercise needed to outweigh the negative effects of stress on AD measures. In addition, we show that chronic physical activity in a mouse model of AD can prevent the effects of acute restraint stress on Aβ levels in the hippocampus. Stress and physical activity have many overlapping and divergent effects on the body and some of the possible mechanisms through which physical activity may protect against stress-induced risk factors for AD are discussed. While the physiological effects of acute stress and acute exercise overlap, chronic effects of physical activity appear to directly oppose the effects of chronic stress on risk factors for AD. Further study is needed to identify optimal parameters for intensity, duration and frequency of physical activity to counterbalance effects of stress on the development and progression of AD. Keywords: Alzheimer's disease, Amyloid, Stress, Exercise, Physical activity

The complement system at the embryo implantation site: friend or foe?

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Roberta eBulla

2012-03-01

Full Text Available An inflammatory-like process and vascular remodeling represent the main changes that occur in decidua in the early phase of pregnancy. These changes are partly induced by trophoblast cells that colonize the decidua and are also contributed by the complement system. C1q is one of the component components produced at feto-maternal interface that serves an important function in placental development. Decidual endothelial cells synthesize and express C1q on the cell surface where it acts as a molecular bridge between endovascular trophoblast and endothelial cells. C1q is also produced by extravillous trophoblast and is used to favor trophoblast migration through the decidua. C7 is another component produced and expressed on the membrane of endothelial cells and is involved in the control of the proinflammatory effect of the terminal complement complex. Defective expression of C1q by trophoblast is associated with impaired trophoblast invasion of decidua and may have important implications in pregnancy disorders such as preeclampsia characterized by reduced vascular remodeling. Local control of complement activation by several complement regulators including cell-bound C7 is critical to prevent complement-mediated tissue damage as suggested by recent data showing an association of preeclampsia with mutations in the genes encoding for some complement regulators.

Circulating immune complexes and complement concentrations in patients with alcoholic liver disease

DEFF Research Database (Denmark)

Gluud, C; Jans, H

1982-01-01

A prospective evaluation of circulating immune complexes (CIC) and the activity of the complement system was undertaken in 53 alcoholic patients just before diagnostic liver biopsy. Circulating immune complexes were detected in 39% of patients with alcoholic steatosis (n = 26), 58% of patients...... with alcoholic hepatitis (n = 12), and 60% of patients with alcoholic cirrhosis (n = 15). No significant difference was found between the three group of patients. The activity of the complement system was within reference limits in the majority of patients and only slight differences were detected between...... the three groups. No significant differences were observed in liver biochemistry and complement concentrations in CIC-positive and CIC-negative patients. Detection of CIC in patients with alcoholic liver disease does not seem to be of any diagnostic value or play any pathogenic role. The high prevalence...

Circulating immune complexes and complement concentrations in patients with alcoholic liver disease

DEFF Research Database (Denmark)

Gluud, C; Jans, H

1982-01-01

A prospective evaluation of circulating immune complexes (CIC) and the activity of the complement system was undertaken in 53 alcoholic patients just before diagnostic liver biopsy. Circulating immune complexes were detected in 39% of patients with alcoholic steatosis (n = 26), 58% of patients...... with alcoholic hepatitis (n = 12), and 60% of patients with alcoholic cirrhosis (n = 15). No significant difference was found between the three group of patients. The activity of the complement system was within reference limits in the majority of patients and only slight differences were detected between...

Shark complement: an assessment.

Science.gov (United States)

Smith, S L

1998-12-01

The classical (CCP) and alternative (ACP) pathways of complement activation have been established for the nurse shark (Ginglymostoma cirratum). The isolation of a cDNA clone encoding a mannan-binding protein-associated serine protease (MASP)-1-like protein from the Japanese dogfish (Triakis scyllia) suggests the presence of a lectin pathway. The CCP consists of six functionally distinct components: C1n, C2n, C3n, C4n, C8n and C9n, and is activated by immune complexes in the presence of Ca++ and Mg++ ions. The ACP is antibody independent, requiring Mg++ ions and a heat-labile 90 kDa factor B-like protein for activity. Proteins considered homologues of C1q, C3 and C4 (C2n) of the mammalian complement system have been isolated from nurse shark serum. Shark C1q is composed of at least two chain types each showing 50% identity to human C1q chains A and B. Partial sequence of the globular domain of one of the chains shows it to be C1q-like rather than like mannan-binding protein. N-terminal amino acid sequences of the alpha and beta chain of shark C3 and C4 molecules show significant identity with corresponding human C3 and C4 chains. A sequence representing shark C4 gamma chain, shows little similarity to human C4 gamma chain. The terminal shark components C8n and C9n are functional analogues of mammalian C8 and C9. Anaphylatoxin activity has been demonstrated in activated shark serum, and porcine C5a desArg induces shark leucocyte chemotaxis. The deduced amino acid sequence of a partial C3 cDNA clone from the nurse shark shows 50%, 30% and 24% homology with the corresponding region of mammalian C3, C4 and alpha 2-macroglobulin. Deduced amino acid sequence data from partial Bf/C2 cDNA clones, two from the nurse shark and one from the Japanese dogfish, suggest that at least one species of elasmobranch has two distinct Bf/C2 genes.

Down-regulation of complement receptors on the surface of host monocyte even as in vitro complement pathway blocking interferes in dengue infection.

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Cintia Ferreira Marinho

Full Text Available In dengue virus (DENV infection, complement system (CS activation appears to have protective and pathogenic effects. In severe dengue fever (DF, the levels of DENV non-structural-1 protein and of the products of complement activation, including C3a, C5a and SC5b-9, are higher before vascular leakage occurs, supporting the hypothesis that complement activation contributes to unfavourable outcomes. The clinical manifestations of DF range from asymptomatic to severe and even fatal. Here, we aimed to characterise CS by their receptors or activation product, in vivo in DF patients and in vitro by DENV-2 stimulation on monocytes. In comparison with healthy controls, DF patients showed lower expression of CR3 (CD11b, CR4 (CD11c and, CD59 on monocytes. The DF patients who were high producers of SC5b-9 were also those that showed more pronounced bleeding or vascular leakage. Those findings encouraged us to investigate the role of CS in vitro, using monocytes isolated from healthy subjects. Prior blocking with CR3 alone (CD11b or CR3 (CD11b/CD18 reduced viral infection, as quantified by the levels of intracellular viral antigen expression and soluble DENV non-structural viral protein. However, we found that CR3 alone (CD11b or CR3 (CD11b/CD18 blocking did not influence major histocompatibility complex presentation neither active caspase-1 on monocytes, thus probably ruling out inflammasome-related mechanisms. Although it did impair the secretion of tumour necrosis factor alpha and interferon alpha. Our data provide strategies of blocking CR3 (CD11b pathways could have implications for the treatment of viral infection by antiviral-related mechanisms.

Complement activation in Ghanaian children with severe Plasmodium falciparum malaria

DEFF Research Database (Denmark)

Helegbe, Gideon K; Goka, Bamenla Q; Kurtzhals, Jørgen

2007-01-01

BACKGROUND: Severe anaemia (SA), intravascular haemolysis (IVH) and respiratory distress (RD) are severe forms of Plasmodium falciparum malaria, with RD reported to be of prognostic importance in African children with malarial anaemia. Complement factors have been implicated in the mechanism lead...

Maternal Active Mastication during Prenatal Stress Ameliorates Prenatal Stress-Induced Lower Bone Mass in Adult Mouse Offspring.

Science.gov (United States)

Azuma, Kagaku; Ogura, Minori; Kondo, Hiroko; Suzuki, Ayumi; Hayashi, Sakurako; Iinuma, Mitsuo; Onozuka, Minoru; Kubo, Kin-Ya

2017-01-01

Chronic psychological stress is a risk factor for osteoporosis. Maternal active mastication during prenatal stress attenuates stress response. The aim of this study is to test the hypothesis that maternal active mastication influences the effect of prenatal stress on bone mass and bone microstructure in adult offspring. Pregnant ddY mice were randomly divided into control, stress, and stress/chewing groups. Mice in the stress and stress/chewing groups were placed in a ventilated restraint tube for 45 minutes, 3 times a day, and was initiated on day 12 of gestation and continued until delivery. Mice in the stress/chewing group were allowed to chew a wooden stick during the restraint stress period. The bone response of 5-month-old male offspring was evaluated using quantitative micro-CT, bone histomorphometry, and biochemical markers. Prenatal stress resulted in significant decrease of trabecular bone mass in both vertebra and distal femur of the offspring. Maternal active mastication during prenatal stress attenuated the reduced bone formation and increased bone resorption, improved the lower trabecular bone volume and bone microstructural deterioration induced by prenatal stress in the offspring. These findings indicate that maternal active mastication during prenatal stress can ameliorate prenatal stress-induced lower bone mass of the vertebra and femur in adult offspring. Active mastication during prenatal stress in dams could be an effective coping strategy to prevent lower bone mass in their offspring.

Arctigenin alleviates ER stress via activating AMPK

Science.gov (United States)

Gu, Yuan; Sun, Xiao-xiao; Ye, Ji-ming; He, Li; Yan, Shou-sheng; Zhang, Hao-hao; Hu, Li-hong; Yuan, Jun-ying; Yu, Qiang

2012-01-01

Aim: To investigate the protective effects of arctigenin (ATG), a phenylpropanoid dibenzylbutyrolactone lignan from Arctium lappa L (Compositae), against ER stress in vitro and the underlying mechanisms. Methods: A cell-based screening assay for ER stress regulators was established. Cell viability was measured using MTT assay. PCR and Western blotting were used to analyze gene and protein expression. Silencing of the CaMKKβ, LKB1, and AMPKα1 genes was achieved by RNA interference (RNAi). An ATP bioluminescent assay kit was employed to measure the intracellular ATP levels. Results: ATG (2.5, 5 and 10 μmol/L) inhibited cell death and unfolded protein response (UPR) in a concentration-dependent manner in cells treated with the ER stress inducer brefeldin A (100 nmol/L). ATG (1, 5 and 10 μmol/L) significantly attenuated protein synthesis in cells through inhibiting mTOR-p70S6K signaling and eEF2 activity, which were partially reversed by silencing AMPKα1 with RNAi. ATG (1-50 μmol/L) reduced intracellular ATP level and activated AMPK through inhibiting complex I-mediated respiration. Pretreatment of cells with the AMPK inhibitor compound C (25 μmol/L) rescued the inhibitory effects of ATG on ER stress. Furthermore, ATG (2.5 and 5 μmol/L) efficiently activated AMPK and reduced the ER stress and cell death induced by palmitate (2 mmol/L) in INS-1 β cells. Conclusion: ATG is an effective ER stress alleviator, which protects cells against ER stress through activating AMPK, thus attenuating protein translation and reducing ER load. PMID:22705729

Pathogens' toolbox to manipulate human complement.

Science.gov (United States)

Fernández, Francisco J; Gómez, Sara; Vega, M Cristina

2017-12-14

The surveillance and pathogen fighting functions of the complement system have evolved to protect mammals from life-threatening infections. In turn, pathogens have developed complex molecular mechanisms to subvert, divert and evade the effector functions of the complement. The study of complement immunoevasion by pathogens sheds light on their infection drivers, knowledge that is essential to implement therapies. At the same time, complement evasion also acts as a discovery ground that reveals important aspects of how complement works under physiological conditions. In recent years, complex interrelationships between infection insults and the onset of autoimmune and complement dysregulation diseases have led to propose that encounters with pathogens can act as triggering factors for disease. The correct management of these diseases involves the recognition of their triggering factors and the development and administration of complement-associated molecular therapies. Even more recently, unsuspected proteins from pathogens have been shown to possess moonlighting functions as virulence factors, raising the possibility that behind the first line of virulence factors there be many more pathogen proteins playing secondary, helping and supporting roles for the pathogen to successfully establish infections. In an era where antibiotics have a progressively reduced effect on the management and control of infectious diseases worldwide, knowledge on the mechanisms of pathogenic invasion and evasion look more necessary and pressing than ever. Copyright © 2017 Elsevier Ltd. All rights reserved.

Interactions of the humoral pattern recognition molecule PTX3 with the complement system

DEFF Research Database (Denmark)

Doni, Andrea; Garlanda, Cecilia; Bottazzi, Barbara

2012-01-01

The innate immune system comprises a cellular and a humoral arm. The long pentraxin PTX3 is a fluid phase pattern recognition molecule, which acts as an essential component of the humoral arm of innate immunity. PTX3 has antibody-like properties including interactions with complement components....... PTX3 interacts with C1q, ficolin-1 and ficolin-2 as well as mannose-binding lectin, recognition molecules in the classical and lectin complement pathways. The formation of these heterocomplexes results in cooperative pathogen recognition and complement activation. Interactions with C4b binding protein...

Aloe vera enhances the innate immune response of pacu (Piaractus mesopotamicus) after transport stress and combined heat killed Aeromonas hydrophila infection.

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Zanuzzo, Fábio S; Sabioni, Rafael E; Montoya, Luz Natalia F; Favero, Gisele; Urbinati, Elisabeth C

2017-06-01

In this study, pacu (Piaractus mesopotamicus) were fed with diets containing Aloe vera for 10 days prior to transport stress and infection with heat killed Aeromonas hydrophila. A. vera is popular around the world due to its medicinal properties, including immunostimulatory effects which was observed in this study. The results show that transport causes immunosuppression, an effect that was prevented by A. vera. Specifically, A. vera prevented reductions of both leukocyte respiratory burst and hemolytic activity of complement system caused by transport. Further, fish fed with A. vera also showed significantly higher leukocyte respiratory burst, serum lysozyme concentrations and activity of complement system 24 h after bacterial infection. Additionally, we observed that A. vera may modulate the innate response through activation of complement system during bacterial immune stimulation. In summary, A. vera extract enhanced innate immune parameters and consequently the ability of fish to cope with pathogens following transport stress. These findings show that A. vera has promise for use in aquaculture and add further evidence that medicinal herbs added to fish feed assist to prevent disease outbreaks. Copyright © 2017 Elsevier Ltd. All rights reserved.

Complement plays a central role in Candida albicans-induced cytokine production by human PBMCs

DEFF Research Database (Denmark)

Cheng, Shih-Chin; Sprong, Tom; Joosten, Leo A B

2012-01-01

In experimental studies, the role of complement in antifungal host defense has been attributed to its opsonizing capability. In this study, we report that in humans an activated complement system mainly augments Candida albicans-induced host proinflammatory cytokine production via C5a-C5aR signal...

Complement-mediated solubilization of immune complexes. Solubilization inhibition and complement factor levels in SLE patients

DEFF Research Database (Denmark)

Baatrup, Gunnar; Petersen, Ivan; Kappelgaard, E

1984-01-01

Thirty-two of 36 serum samples from 19 SLE patients showed reduced capacity to mediate complement-dependent solubilization of immune complexes (IC). SLE patients with nephritis exerted the lowest complement-mediated solubilization capacity (CMSC) whereas sera from patients with inactive disease g...

Complement anaphylatoxins as immune regulators in cancer.

Science.gov (United States)

Sayegh, Eli T; Bloch, Orin; Parsa, Andrew T

2014-08-01

The role of the complement system in innate immunity is well characterized. However, a recent body of research implicates the complement anaphylatoxins C3a and C5a as insidious propagators of tumor growth and progression. It is now recognized that certain tumors elaborate C3a and C5a and that complement, as a mediator of chronic inflammation and regulator of immune function, may in fact foster rather than defend against tumor growth. A putative mechanism for this function is complement-mediated suppression of immune effector cells responsible for immunosurveillance within the tumor microenvironment. This paradigm accords with models of immune dysregulation, such as autoimmunity and infectious disease, which have defined a pathophysiological role for abnormal complement signaling. Several types of immune cells express the cognate receptors for the complement anaphylatoxins, C3aR and C5aR, and demonstrate functional modulation in response to complement stimulation. In turn, impairment of antitumor immunity has been intimately tied to tumor progression in animal models of cancer. In this article, the literature was systematically reviewed to identify studies that have characterized the effects of the complement anaphylatoxins on the composition and function of immune cells within the tumor microenvironment. The search identified six studies based upon models of lymphoma and ovarian, cervical, lung, breast, and mammary cancer, which collectively support the paradigm of complement as an immune regulator in the tumor microenvironment. © 2014 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

Activation of Human Complement System by Dextran-Coated Iron Oxide Nanoparticles Is Not Affected by Dextran/Fe Ratio, Hydroxyl Modifications, and Crosslinking

DEFF Research Database (Denmark)

Wang, Guankui; Chen, Fangfang; Banda, Nirmal K

2016-01-01

While having tremendous potential as therapeutic and imaging tools, the clinical use of engineered nanoparticles has been associated with serious safety concerns. Activation of the complement cascade and the release of proinflammatory factors C3a and C5a may contribute to infusion-related reactio...

Complement Test

Science.gov (United States)

... Salicylates Semen Analysis Serotonin Serum Free Light Chains Sex Hormone Binding Globulin (SHBG) Shiga toxin-producing Escherichia ... and forming complexes that respond to infections, non-self tissues (transplants), dead cells ... KJ. Complement determinations in human disease. Ann Allergy Asthma Immunol . 2004; ...

Complement inhibition by hydroxychloroquine prevents placental and fetal brain abnormalities in antiphospholipid syndrome.

Science.gov (United States)

Bertolaccini, Maria Laura; Contento, Gregorio; Lennen, Ross; Sanna, Giovanni; Blower, Philip J; Ma, Michelle T; Sunassee, Kavitha; Girardi, Guillermina

2016-12-01

Placental ischemic disease and adverse pregnancy outcomes are frequently observed in patients with antiphospholipid syndrome (APS). Despite the administration of conventional antithrombotic treatment a significant number of women continue to experience adverse pregnancy outcomes, with uncertain prevention and management. Efforts to develop effective pharmacological strategies for refractory obstetric APS cases will be of significant clinical benefit for both mothers and fetuses. Although the antimalarial drug, hydroxychloroquine (HCQ) is increasingly used to treat pregnant women with APS, little is known about its efficacy and mechanism of action of HCQ. Because complement activation plays a crucial and causative role in placental ischemia and abnormal fetal brain development in APS we hypothesised that HCQ prevents these pregnancy complications through inhibition of complement activation. Using a mouse model of obstetric APS that closely resembles the clinical condition, we found that HCQ prevented fetal death and the placental metabolic changes -measured by proton magnetic resonance spectroscopy in APS-mice. Using 111 In labelled antiphospholipid antibodies (aPL) we identified the placenta and the fetal brain as the main organ targets in APS-mice. Using this same method, we found that HCQ does not inhibit aPL binding to tissues as was previously suggested from in vitro studies. While HCQ did not affect aPL binding to fetal brain it prevented fetal brain abnormal cortical development. HCQ prevented complement activation in vivo and in vitro. Complement C5a levels in serum samples from APS patients and APS-mice were lower after treatment with HCQ while the antibodies titres remained unchanged. HCQ prevented not only placental insufficiency but also abnormal fetal brain development in APS. By inhibiting complement activation, HCQ might also be an effective antithrombotic therapy. Copyright © 2016 Elsevier Ltd. All rights reserved.

Interactions of PLGA nanoparticles with blood components: protein adsorption, coagulation, activation of the complement system and hemolysis studies.

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Fornaguera, Cristina; Calderó, Gabriela; Mitjans, Montserrat; Vinardell, Maria Pilar; Solans, Conxita; Vauthier, Christine

2015-04-14

The intravenous administration of poly(lactic-co-glycolic) acid (PLGA) nanoparticles has been widely reported as a promising alternative for delivery of drugs to specific cells. However, studies on their interaction with diverse blood components using different techniques are still lacking. Therefore, in the present work, the interaction of PLGA nanoparticles with blood components was described using different complementary techniques. The influence of different encapsulated compounds/functionalizing agents on these interactions was also reported. It is worth noting that all these techniques can be simply performed, without the need for highly sophisticated apparatus or skills. Moreover, their transference to industries and application of quality control could be easily performed. Serum albumin was adsorbed onto all types of tested nanoparticles. The saturation concentration was dependent on the nanoparticle size. In contrast, fibrinogen aggregation was dependent on nanoparticle surface charge. The complement activation was also influenced by the nanoparticle functionalization; the presence of a functionalizing agent increased complement activation, while the addition of an encapsulated compound only caused a slight increase. None of the nanoparticles influenced the coagulation cascade at low concentrations. However, at high concentrations, cationized nanoparticles did activate the coagulation cascade. Interactions of nanoparticles with erythrocytes did not reveal any hemolysis. Interactions of PLGA nanoparticles with blood proteins depended both on the nanoparticle properties and the protein studied. Independent of their loading/surface functionalization, PLGA nanoparticles did not influence the coagulation cascade and did not induce hemolysis of erythrocytes; they could be defined as safe concerning induction of embolization and cell lysis.

Cytokinin Activity in Water-stressed Shoots 1

Science.gov (United States)

Itai, Chanan; Vaadia, Yoash

1971-01-01

Water stress applied to the plant shoot through enhanced evaporative demands reduced cytokinin activity in extracts of xylem exudate and leaves. This reduction resembled the changes in cytokinin activity caused by water stress applied to the root. Cytokinin activity in detached wilting leaves decreased rapidly. Recovery took place after several hours in a humid chamber. Experiments with 14C-kinetin indicated that the mechanism of the inactivation and its reversal involve a chemical transformation of the cytokinin molecule. PMID:16657585

Effect of b-Propiolactone treatment on the complement activation mediated by equine antisera

Directory of Open Access Journals (Sweden)

Rosalvo GUIDOLIN

1997-03-01

Full Text Available Reduction of complement activation through an alteration of the Fc fragment of immunoglobulins by b-propiolactone treatment was carried out in equine antisera raised against rabies virus, Bothrops venoms and diphtherial toxin. Results were evaluated by means of an anaphylactic test performed on guinea-pigs, and compared to the ones obtained with the same sera purified by saline precipitation (ammonium sulfate, followed or not by enzymatic digestion with pepsin. Protein purity levels for antibothropic serum were 184.5 mg/g and 488.5 mg/g in b-propiolactone treated and pepsin-digested sera, respectively. The recovery of specific activity was 100% and 62.5% when using antibothropic serum treated by b-propiolactone and pepsin digestion, respectively. The antidiphtherial and anti-rabies sera treated with b-propiolactone and pepsin presented protein purity levels of 5,698 and 7,179 Lf/g, 16,233 and 6,784 IU/g, respectively. The recovery of specific activity for these antisera were 88.8%, 77.7%, 100% and 36,5%, respectively. b-propiolactone treatment induced a reduction in complement activation, tested "in vivo", without significant loss of biological activity. This treatment can be used in the preparation of heterologous immunoglobulins for human use.Efeito do tratamento de antissoros equinos pela b-propiolactona na ativação do complemento. A redução da ativação do complemento através de uma alteração do fragmento Fc das imunoglobulinas pela b-propiolactona foi obtida em soros hiperimunes equinos antivirus rábico, venenos Bothrops e toxina diftérica. Os resultados foram avaliados por teste de anafilaxia em cobaias, e comparados com aqueles obtidos com os mesmos soros purificados por precipitação salina (sulfato de amônio, seguidos ou não por digestão enzimática com pepsina. Os níveis de pureza protéica foram para o soro antibotrópico de 184.5 mg/g e 488.5 mg/g tratado pela b-propiolactona e digeridos pela pepsina, respectivamente

Age-related macular degeneration and modification of systemic complement factor H production through liver transplantation.

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Khandhadia, Samir; Hakobyan, Svetlana; Heng, Ling Z; Gibson, Jane; Adams, David H; Alexander, Graeme J; Gibson, Jonathan M; Martin, Keith R; Menon, Geeta; Nash, Kathryn; Sivaprasad, Sobha; Ennis, Sarah; Cree, Angela J; Morgan, B Paul; Lotery, Andrew J

2013-08-01

To investigate whether modification of liver complement factor H (CFH) production, by alteration of liver CFH Y402H genotype through liver transplantation (LT), influences the development of age-related macular degeneration (AMD). Multicenter, cross-sectional study. We recruited 223 Western European patients ≥ 55 years old who had undergone LT ≥ 5 years previously. We determined AMD status using a standard grading system. Recipient CFH Y402H genotype was obtained from DNA extracted from recipient blood samples. Donor CFH Y402H genotype was inferred from recipient plasma CFH Y402H protein allotype, measured using enzyme-linked immunosorbent assays. This approach was verified by genotyping donor tissue from a subgroup of patients. Systemic complement activity was ascertained by measuring levels of plasma complement proteins using an enzyme-linked immunosorbent assay, including substrates (C3, C4), activation products (C3a, C4a, and terminal complement complex), and regulators (total CFH, C1 inhibitor). We evaluated AMD status and recipient and donor CFH Y402H genotype. In LT patients, AMD was associated with recipient CFH Y402H genotype (P = 0.036; odds ratio [OR], 1.6; 95% confidence interval [CI], 1.0-2.4) but not with donor CFH Y402H genotype (P = 0.626), after controlling for age, sex, smoking status, and body mass index. Recipient plasma CFH Y402H protein allotype predicted donor CFH Y402H genotype with 100% accuracy (n = 49). Plasma complement protein or activation product levels were similar in LT patients with and without AMD. Compared with previously reported prevalence figures (Rotterdam Study), LT patients demonstrated a high prevalence of both AMD (64.6% vs 37.1%; OR, 3.09; Pproduction. In addition, AMD is not associated with systemic complement activity in LT patients. These findings suggest that local intraocular complement activity is of greater importance in AMD pathogenesis. The high AMD prevalence observed in LT patients may be associated with

The mitochondrial cytochrome c peroxidase Ccp1 of Saccharomyces cerevisiae is involved in conveying an oxidative stress signal to the transcription factor Pos9 (Skn7).

Science.gov (United States)

Charizanis, C; Juhnke, H; Krems, B; Entian, K D

1999-10-01

In Saccharomyces cerevisiae two transcription factors, Pos9 (Skn7) and Yap1, are involved in the response to oxidative stress. Fusion of the Pos9 response-regulator domain to the Gal4 DNA-binding domain results in a transcription factor which renders the expression of a GAL1-lacZ reporter gene dependent on oxidative stress. To identify genes which are involved in the oxygen-dependent activation of the Gal4-Pos9 hybrid protein we screened for mutants that failed to induce the heterologous test system upon oxidative stress (fap mutants for factors activating Pos9). We isolated several respiration-deficient and some respiration-competent mutants by this means. We selected for further characterization only those mutants which also displayed an oxidative-stress-sensitive phenotype. One of the respiration-deficient mutants (complementation groupfap6) could be complemented by the ISM1 gene, which encodes mitochondrial isoleucyl tRNA synthetase, suggesting that respiration competence was important for signalling of oxidative stress. In accordance with this notion a rho0 strain and a wild-type strain in which respiration had been blocked (by treatment with antimycin A or with cyanide) also failed to activate Gal4-Pos9 upon imposition of oxidative stress. Another mutant, fap24, which was respiration-competent, could be complemented by CCP1, which encodes the mitochondrial cytochrome c peroxidase. Mitochondrial cytochrome c peroxidase degrades reactive oxygen species within the mitochondria. This suggested a possible sensor function for the enzyme in the oxidative stress response. To test this we used the previously described point mutant ccp1 W191F, which is characterized by a 10(4)-fold decrease in electron flux between cytochrome c and cytochrome c peroxidase. The Ccp1W191F mutant was still capable of activating the Pos9 transcriptional activation domain, suggesting that the signalling function of Ccp1 is independent of electron flux rates.

Therapeutic inhibition of the complement system. Y2K update.

Science.gov (United States)

Asghar, S S; Pasch, M C

2000-09-01

Activation of complement is an essential part of the mechanism of pathogenesis of a large number of human diseases; its inhibition by pharmacological means is likely to suppress disease processes in complement mediated diseases. From this point of view low molecular weight synthetic inhibitors of complement are being developed and high molecular weight natural inhibitors of human origin present in plasma or embedded in cell membrane are being purified or produced in their recombinant forms. This review is concerned with high molecular weight inhibitors, some of which are already in clinical use but may be efficacious in many other diseases in which they have not yet been tried. C1-esterase inhibitor (C1-INH) concentrate prepared from human plasma is being successfully used for the treatment of hereditary angioneurotic edema. Recently, C1-INH has been found to be consumed in severe inflammation and has been shown to exert beneficial effects in several inflammatory conditions such as human sepsis, post-operative myocardial dysfunction due to reperfusion injury, severe capillary leakage syndrome after bone marrow transplantation, reperfusion injury after lung transplantation, burn, and cytotoxicity caused by IL-2 therapy in cancer. Factor I has been used for the treatment of factor I deficiency. Recombinant soluble forms of membrane cofactor protein (MCP), and decay accelerating factor (DAF) have not yet been tried in humans but have been shown to be effective in immune complex mediate inflammation in animals. Organs of pigs transgenic for one or more of human membrane regulators of complement namely membrane cofactor protein (MCP), decay accelerating factor (DAF) or CD59, are being produced for transplantation into humans. They have been shown to be resistant to hyperacute rejection in non-human primates; acute vascular rejection is still a problem in their clinical use. It is hoped that these observations together with future developments will make xeno

Psychosocial versus physiological stress – meta-analyses on deactivations and activations of the neural correlates of stress reactions

Science.gov (United States)

Kogler, Lydia; Mueller, Veronika I.; Chang, Amy; Eickhoff, Simon B.; Fox, Peter T.; Gur, Ruben C.; Derntl, Birgit

2015-01-01

Stress is present in everyday life in various forms and situations. Two stressors frequently investigated are physiological and psychosocial stress. Besides similar subjective and hormonal responses, it has been suggested that they also share common neural substrates. The current study used activation-likelihood-estimation meta-analysis to test this assumption by integrating results of previous neuroimaging studies on stress processing. Reported results are cluster-level FWE corrected. The inferior frontal gyrus (IFG) and the anterior insula (AI) were the only regions that demonstrated overlapping activation for both stressors. Analysis of physiological stress showed consistent activation of cognitive and affective components of pain processing such as the insula, striatum, or the middle cingulate cortex. Contrarily, analysis across psychosocial stress revealed consistent activation of the right superior temporal gyrus and deactivation of the striatum. Notably, parts of the striatum appeared to be functionally specified: the dorsal striatum was activated in physiological stress, whereas the ventral striatum was deactivated in psychosocial stress. Additional functional connectivity and decoding analyses further characterized this functional heterogeneity and revealed higher associations of the dorsal striatum with motor regions and of the ventral striatum with reward processing. Based on our meta-analytic approach, activation of the IFG and the AI seems to indicate a global neural stress reaction. While physiological stress activates a motoric fight-or-flight reaction, during psychosocial stress attention is shifted towards emotion regulation and goal-directed behavior, and reward processing is reduced. Our results show the significance of differentiating physiological and psychosocial stress in neural engagement. Furthermore, the assessment of deactivations in addition to activations in stress research is highly recommended. PMID:26123376

Complement anaphylatoxins as immune regulators in cancer

OpenAIRE

Sayegh, Eli T; Bloch, Orin; Parsa, Andrew T

2014-01-01

The role of the complement system in innate immunity is well characterized. However, a recent body of research implicates the complement anaphylatoxins C3a and C5a as insidious propagators of tumor growth and progression. It is now recognized that certain tumors elaborate C3a and C5a and that complement, as a mediator of chronic inflammation and regulator of immune function, may in fact foster rather than defend against tumor growth. A putative mechanism for this function is complement-mediat...

Targeted Delivery of Neutralizing Anti-C5 Antibody to Renal Endothelium Prevents Complement-Dependent Tissue Damage

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Paolo Durigutto

2017-09-01

Full Text Available Complement activation is largely implicated in the pathogenesis of several clinical conditions and its therapeutic neutralization has proven effective in preventing tissue and organ damage. A problem that still needs to be solved in the therapeutic control of complement-mediated diseases is how to avoid side effects associated with chronic neutralization of the complement system, in particular, the increased risk of infections. We addressed this issue developing a strategy based on the preferential delivery of a C5 complement inhibitor to the organ involved in the pathologic process. To this end, we generated Ergidina, a neutralizing recombinant anti-C5 human antibody coupled with a cyclic-RGD peptide, with a distinctive homing property for ischemic endothelial cells and effective in controlling tissue damage in a rat model of renal ischemia/reperfusion injury (IRI. As a result of its preferential localization on renal endothelium, the molecule induced complete inhibition of complement activation at tissue level, and local protection from complement-mediated tissue damage without affecting circulating C5. The ex vivo binding of Ergidina to surgically removed kidney exposed to cold ischemia supports its therapeutic use to prevent posttransplant IRI leading to delay of graft function. Moreover, the finding that the ex vivo binding of Ergidina was not restricted to the kidney, but was also seen on ischemic heart, suggests that this RGD-targeted anti-C5 antibody may represent a useful tool to treat organs prior to transplantation. Based on this evidence, we propose preliminary data showing that Ergidina is a novel targeted drug to prevent complement activation on the endothelium of ischemic kidney.

conformational complexity of complement component C3

NARCIS (Netherlands)

Janssen, B.J.C.

2007-01-01

The complement system is an important part of the immune system and critical for the elimination of pathogens. In mammals the complement system consists of an intricate set of about 35 soluble and cell-surface plasma proteins. Central to complement is component C3, a large protein of 1,641 residues.

M-ficolin, an innate immune defence molecule, binds patterns of acetyl groups and activates complement

DEFF Research Database (Denmark)

Frederiksen, Pernille Dorthea; Thiel, Steffen; Larsen, Claus Bindslev

2005-01-01

Ficolins play a role in the innate immune defence as pathogen-associated molecular pattern recognition molecules. Three ficolins are found in humans: H-ficolin, L-ficolin and M-ficolin. L-ficolin and H-ficolin circulate in blood in complexes with mannan-binding lectin-associated serine proteases...... (MASPs) and are capable of activating the complement system. L-ficolin shows affinity for acetylated compounds and binds to various capsulated strains of bacteria. H-ficolin has been shown to bind Aerococcus viridans. Less is known about M-ficolin, but it is thought to be present only on monocytes. We...... system. We developed a monoclonal rat anti-human-M/L-ficolin antibody and verified by flow cytometric analysis the presence of ficolin on the surface of peripheral blood monocytes....

Incident microalbuminuria and complement factor mannan-binding lectin-associated protein 19 in people with newly diagnosed type 1 diabetes

DEFF Research Database (Denmark)

Ostergaard, J A; Thiel, S; Hoffmann-Petersen, I T

2017-01-01

BACKGROUND: Evidence links the lectin pathway of complement activation to diabetic kidney disease. Upon carbohydrate-recognition by pattern-recognition molecules, e.g., mannan-binding lectin (MBL), the MBL-associated serine protease (MASP-2) is activated and initiates the complement cascade. The ...

Quiescent complement in nonhuman primates during E coli Shiga toxin-induced hemolytic uremic syndrome and thrombotic microangiopathy.

Science.gov (United States)

Lee, Benjamin C; Mayer, Chad L; Leibowitz, Caitlin S; Stearns-Kurosawa, D J; Kurosawa, Shinichiro

2013-08-01

Enterohemorrhagic Escherichia coli (EHEC) produce ribosome-inactivating Shiga toxins (Stx1, Stx2) responsible for development of hemolytic uremic syndrome (HUS) and acute kidney injury (AKI). Some patients show complement activation during EHEC infection, raising the possibility of therapeutic targeting of complement for relief. Our juvenile nonhuman primate (Papio baboons) models of endotoxin-free Stx challenge exhibit full spectrum HUS, including thrombocytopenia, hemolytic anemia, and AKI with glomerular thrombotic microangiopathy. There were no significant increases in soluble terminal complement complex (C5b-9) levels after challenge with lethal Stx1 (n = 6) or Stx2 (n = 5) in plasma samples from T0 to euthanasia at 49.5 to 128 hours post-challenge. d-dimer and cell injury markers (HMGB1, histones) confirmed coagulopathy and cell injury. Thus, complement activation is not required for the development of thrombotic microangiopathy and HUS induced by EHEC Shiga toxins in these preclinical models, and benefits or risks of complement inhibition should be studied further for this infection.

Evaluation of complement proteins as screening markers for colorectal cancer

DEFF Research Database (Denmark)

Storm, Line; Christensen, Ib J; Jensenius, Jens C

2015-01-01

BACKGROUND: Colorectal cancer (CRC) is a leading cause of cancer death worldwide. Lack of symptoms results in late detection and increased mortality. Inflammation, including complement activation, plays an important role in tumorigenesis. EXPERIMENTAL DESIGN: The concentrations of nine proteins...

The effects of stress on physical activity and exercise.

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Stults-Kolehmainen, Matthew A; Sinha, Rajita

2014-01-01

Psychological stress and physical activity (PA) are believed to be reciprocally related; however, most research examining the relationship between these constructs is devoted to the study of exercise and/or PA as an instrument to mitigate distress. The aim of this paper was to review the literature investigating the influence of stress on indicators of PA and exercise. A systematic search of Web of Science, PubMed, and SPORTDiscus was employed to find all relevant studies focusing on human participants. Search terms included "stress", "exercise", and "physical activity". A rating scale (0-9) modified for this study was utilized to assess the quality of all studies with multiple time points. The literature search found 168 studies that examined the influence of stress on PA. Studies varied widely in their theoretical orientation and included perceived stress, distress, life events, job strain, role strain, and work-family conflict but not lifetime cumulative adversity. To more clearly address the question, prospective studies (n = 55) were considered for further review, the majority of which indicated that psychological stress predicts less PA (behavioral inhibition) and/or exercise or more sedentary behavior (76.4 %). Both objective (i.e., life events) and subjective (i.e., distress) measures of stress related to reduced PA. Prospective studies investigating the effects of objective markers of stress nearly all agreed (six of seven studies) that stress has a negative effect on PA. This was true for research examining (a) PA at periods of objectively varying levels of stress (i.e., final examinations vs. a control time point) and (b) chronically stressed populations (e.g., caregivers, parents of children with a cancer diagnosis) that were less likely to be active than controls over time. Studies examining older adults (>50 years), cohorts with both men and women, and larger sample sizes (n > 100) were more likely to show an inverse association. 85.7 % of higher

Inhibition of the classical pathway of the complement system by saliva of Amblyomma cajennense (Acari: Ixodidae).

Science.gov (United States)

Franco, Paula F; Silva, Naylene C S; Fazito do Vale, Vladimir; Abreu, Jéssica F; Santos, Vânia C; Gontijo, Nelder F; Valenzuela, Jesus G; Pereira, Marcos H; Sant'Anna, Mauricio R V; Gomes, Alessandra P S; Araujo, Ricardo N

2016-05-01

Inhibition of the complement system during and after haematophagy is of utmost importance for tick success in feeding and tick development. The role of such inhibition is to minimise damage to the intestinal epithelium as well as avoiding inflammation and opsonisation of salivary molecules at the bite site. Despite its importance, the salivary anti-complement activity has been characterised only in species belonging to the Ixodes ricinus complex which saliva is able to inhibit the alternative and lectin pathways. Little is known about this activity in other species of the Ixodidae family. Thus, the aim of this study was to describe the inhibition of the classical pathway of the complement system by the saliva of Amblyomma cajennense at different stages of the haematophagy. The A. cajennense saliva and salivary gland extract (SGE) were able to inhibit the complement classical pathway through haemolytic assays with higher activity observed when saliva was used. The anti-complement activity is present in the salivary glands of starving females and also in females throughout the whole feeding process, with significant higher activity soon after tick detachment. The SGE activity from both females fed on mice or horses had no significant correlation (p > 0.05) with tick body weight. The pH found in the intestinal lumen of A. cajennense was 8.04 ± 0.08 and haemolytic assays performed at pH 8.0 showed activation of the classical pathway similarly to what occurs at pH 7.4. Consequently, inhibition could be necessary to protect the tick enterocytes. Indeed, the inhibition observed by SGE was higher in pH 8.0 in comparison to pH 7.4 reinforcing the role of saliva in protecting the intestinal cells. Further studies should be carried out in order to identify the inhibitor molecule and characterise its inhibition mechanism. Copyright © 2016 Elsevier Inc. All rights reserved.

Lupus anticoagulant, disease activity and low complement in the first trimester are predictive of pregnancy loss.

Science.gov (United States)

Mankee, Anil; Petri, Michelle; Magder, Laurence S

2015-01-01

Multiple factors, including proteinuria, antiphospholipid syndrome, thrombocytopenia and hypertension, are predictive of pregnancy loss in systemic lupus erythematosus (SLE). In the PROMISSE study of predictors of pregnancy loss, only a battery of lupus anticoagulant tests was predictive of a composite of adverse pregnancy outcomes. We examined the predictive value of one baseline lupus anticoagulant test (dilute Russell viper venom time) with pregnancy loss in women with SLE. From the Hopkins Lupus Cohort, there were 202 pregnancies from 175 different women after excluding twin pregnancies and pregnancies for which we did not have a first trimester assessment of lupus anticoagulant. We determined the percentage of women who had a pregnancy loss in groups defined by potential risk factors. The lupus anticoagulant was determined by dilute Russell viper venom time with appropriate mixing and confirmatory testing. Generalised estimating equations were used to calculate p values, accounting for repeated pregnancies in the same woman. The age at pregnancy was 40 (3%). 55% were Caucasian and 34% African-American. Among those with lupus anticoagulant during the first trimester, 6/16 (38%) experienced a pregnancy loss compared with only 16/186 (9%) of other pregnancies (p=0.003). In addition, those with low complement or higher disease activity had a higher rate of pregnancy loss than those without (p=0.049 and 0.005, respectively). In contrast, there was no association between elevated anticardiolipin in the first trimester and pregnancy loss. The strongest predictor of pregnancy loss in SLE in the first trimester is the lupus anticoagulant. In addition, moderate disease activity by the physician global assessment and low complement measured in the first trimester were predictive of pregnancy loss. These data suggest that treatment of the lupus anticoagulant could be considered, even in the absence of history of pregnancy loss.

High-throughput selection for cellulase catalysts using chemical complementation.

Science.gov (United States)

Peralta-Yahya, Pamela; Carter, Brian T; Lin, Hening; Tao, Haiyan; Cornish, Virginia W

2008-12-24

Efficient enzymatic hydrolysis of lignocellulosic material remains one of the major bottlenecks to cost-effective conversion of biomass to ethanol. Improvement of glycosylhydrolases, however, is limited by existing medium-throughput screening technologies. Here, we report the first high-throughput selection for cellulase catalysts. This selection was developed by adapting chemical complementation to provide a growth assay for bond cleavage reactions. First, a URA3 counter selection was adapted to link chemical dimerizer activated gene transcription to cell death. Next, the URA3 counter selection was shown to detect cellulase activity based on cleavage of a tetrasaccharide chemical dimerizer substrate and decrease in expression of the toxic URA3 reporter. Finally, the utility of the cellulase selection was assessed by isolating cellulases with improved activity from a cellulase library created by family DNA shuffling. This application provides further evidence that chemical complementation can be readily adapted to detect different enzymatic activities for important chemical transformations for which no natural selection exists. Because of the large number of enzyme variants that selections can now test as compared to existing medium-throughput screens for cellulases, this assay has the potential to impact the discovery of improved cellulases and other glycosylhydrolases for biomass conversion from libraries of cellulases created by mutagenesis or obtained from natural biodiversity.

N-terminal prodomain of Pfs230 synthesized using a cell-free system is sufficient to induce complement-dependent malaria transmission-blocking activity.

Science.gov (United States)

Tachibana, Mayumi; Wu, Yimin; Iriko, Hideyuki; Muratova, Olga; MacDonald, Nicholas J; Sattabongkot, Jetsumon; Takeo, Satoru; Otsuki, Hitoshi; Torii, Motomi; Tsuboi, Takafumi

2011-08-01

The aim of a malaria transmission-blocking vaccine is to block the development of malaria parasites in the mosquito and thus prevent subsequent infection of the human host. Previous studies have demonstrated that the gametocyte/gamete surface protein Pfs230 can induce transmission-blocking immunity and have evaluated Escherichia coli-produced Pfs230 as a transmission-blocking vaccine candidate. In this study, we used the wheat germ cell-free expression system to produce N-terminal fragments of Pfs230 and evaluated the transmission-blocking activity of antisera raised against the recombinant Pfs230 protein. The rabbit antisera reacted to the surface of cultured gametocytes and gametes of the Plasmodium falciparum NF54 line, recognized the 360-kDa form of parasite-produced Pfs230 by Western blot assay, and reduced the infectivity of NF54 parasites to Anopheles stefensi mosquitoes in the presence of complement in a standard membrane feeding assay. Thus, our data demonstrate that the N-terminal pro domain of Pfs230 is sufficient to induce complement-dependent transmission-blocking activity against P. falciparum.

The effect of storage temperature on the biological activity of extracellular vesicles for the complement system.

Science.gov (United States)

Park, Sang June; Jeon, Hyungtaek; Yoo, Seung-Min; Lee, Myung-Shin

2018-05-10

Extracellular vesicles (EVs) are mediators of intercellular communication by transporting cargo containing proteins, lipids, mRNA, and miRNA. There is increasing evidence that EVs have various roles in regulating migration, invasion, stemness, survival, and immune functions. Previously, we have found that EVs from Kaposi's sarcoma-associated herpesvirus (KSHV)-infected human endothelial cells have the potential to activate the complement system. Although many studies have shown that the physical properties of EVs can be changed by their storage condition, there have been few studies for the stability of biological activity of EVs in various storage conditions. In this study, we investigated various conditions to identify the best conditions to store EVs with functional stability for 25 d. Furthermore, the correlation between the function and other characteristics of EVs, including the expression of EV markers, size distribution, and particle number, were also analyzed. Our results demonstrated that storage temperature is an important factor to maintain the activity of EVs and would be useful information for basic research and clinical application using EVs.

Trichinella spiralis Calreticulin Binds Human Complement C1q As an Immune Evasion Strategy.

Science.gov (United States)

Zhao, Limei; Shao, Shuai; Chen, Yi; Sun, Ximeng; Sun, Ran; Huang, Jingjing; Zhan, Bin; Zhu, Xinping

2017-01-01

As a multicellular parasitic nematode, Trichinella spiralis regulates host immune responses by producing a variety of immunomodulatory molecules to escape from host immune attack, but the mechanisms underlying the immune evasion are not well understood. Here, we identified that T. spiralis calreticulin ( Ts -CRT), a Ca 2+ -binding protein, facilitated T. spiralis immune evasion by interacting with the first component of human classical complement pathway, C1q. In the present study, Ts -CRT was found to be expressed on the surface of different developmental stages of T. spiralis as well as in the secreted products of adult and muscle larval worms. Functional analysis identified that Ts -CRT was able to bind to human C1q, resulting in the inhibition of C1q-initiated complement classical activation pathway reflected by reduced C4/C3 generation and C1q-dependent lysis of antibody-sensitized sheep erythrocytes. Moreover, recombinant Ts -CRT (r Ts -CRT) binding to C1q suppressed C1q-induced THP-1-derived macrophages chemotaxis and reduced monocyte-macrophages release of reactive oxygen intermediates (ROIs). Blocking Ts -CRT on the surface of newborn larvae (NBL) of T. spiralis with anti- Ts -CRT antibody increased the C1q-mediated adherence of monocyte-macrophages to larvae and impaired larval infectivity. All of these results suggest that T. spiralis -expressed Ts -CRT plays crucial roles in T. spiralis immune evasion and survival in host mostly by directly binding to host complement C1q, which not only reduces C1q-mediated activation of classical complement pathway but also inhibits the C1q-induced non-complement activation of macrophages.

Complementary Roles of the Classical and Lectin Complement Pathways in the Defense against Aspergillus fumigatus

DEFF Research Database (Denmark)

Rosbjerg, Anne; Genster, Ninette; Pilely, Katrine

2016-01-01

Aspergillus fumigatus infections are associated with a high mortality rate for immunocompromised patients. The complement system is considered to be important in protection against this fungus, yet the course of activation is unclear. The aim of this study was to unravel the role of the classical......, lectin, and alternative pathways under both immunocompetent and immunocompromised conditions to provide a relevant dual-perspective on the response against A. fumigatus. Conidia (spores) from a clinical isolate of A. fumigatus were combined with various human serum types (including serum deficient...... complement on A. fumigatus, but required classical and/or lectin pathway for initiation. In normal human serum, this initiation came primarily from the classical pathway. However, with a dysfunctional classical pathway (C1q-deficient serum), lectin pathway activated complement and mediated opsonophagocytosis...

Reactivity of alpha 1-antitrypsin mutants against proteolytic enzymes of the kallikrein-kinin, complement, and fibrinolytic systems

NARCIS (Netherlands)

Patston, P.A.; Roodi, N.; Schifferli, J.A.; Bischoff, Rainer; Courtney, M.; Schapira, M.

1990-01-01

Increased extracellular proteolysis because of unregulated activation of blood coagulation, complement, and fibrinolysis is observed in thrombosis, shock, and inflammation. In the present study, we have examined whether the plasma kallikrein-kinin system, the classical pathway of complement, and the

Does Host Complement Kill Borrelia burgdorferi within Ticks?

OpenAIRE

Rathinavelu, Sivaprakash; Broadwater, Anne; de Silva, Aravinda M.

2003-01-01

The Lyme disease spirochete, Borrelia burgdorferi, inhabits the gut lumen of the tick vector. At this location the spirochete is exposed to host blood when a tick feeds. We report here on studies that were done with normal and complement-deficient (C3-knockout) mice to determine if the host complement system killed spirochetes within the vector. We found that spirochete numbers within feeding nymphs were not influenced by complement, most likely because host complement was inactivated within ...

Effects of Active Mastication on Chronic Stress-Induced Bone Loss in Mice.

Science.gov (United States)

Azuma, Kagaku; Furuzawa, Manabu; Fujiwara, Shu; Yamada, Kumiko; Kubo, Kin-ya

2015-01-01

Chronic psychologic stress increases corticosterone levels, which decreases bone density. Active mastication or chewing attenuates stress-induced increases in corticosterone. We evaluated whether active mastication attenuates chronic stress-induced bone loss in mice. Male C57BL/6 (B6) mice were randomly divided into control, stress, and stress/chewing groups. Stress was induced by placing mice in a ventilated restraint tube (60 min, 2x/day, 4 weeks). The stress/chewing group was given a wooden stick to chew during the experimental period. Quantitative micro-computed tomography, histologic analysis, and biochemical markers were used to evaluate the bone response. The stress/chewing group exhibited significantly attenuated stress-induced increases in serum corticosterone levels, suppressed bone formation, enhanced bone resorption, and decreased trabecular bone mass in the vertebrae and distal femurs, compared with mice in the stress group. Active mastication during exposure to chronic stress alleviated chronic stress-induced bone density loss in B6 mice. Active mastication during chronic psychologic stress may thus be an effective strategy to prevent and/or treat chronic stress-related osteopenia.

The Effects of Stress on Physical Activity and Exercise

Science.gov (United States)

Stults-Kolehmainen, Matthew A.; Sinha, Rajita

2013-01-01

Background Psychological stress and physical activity (PA) are believed to be reciprocally related; however, most research examining the relationship between these constructs is devoted to the study of exercise and/or PA as an instrument to mitigate distress. Objective The aim of this paper was to review the literature investigating the influence of stress on indicators of PA and exercise. Methods A systematic search of Web of Science, Pub-Med, and SPORTDiscus was employed to find all relevant studies focusing on human participants. Search terms included “stress”, “exercise”, and “physical activity”. A rating scale (0–9) modified for this study was utilized to assess the quality of all studies with multiple time points. Results The literature search found 168 studies that examined the influence of stress on PA. Studies varied widely in their theoretical orientation and included perceived stress, distress, life events, job strain, role strain, and work–family conflict but not lifetime cumulative adversity. To more clearly address the question, prospective studies (n = 55) were considered for further review, the majority of which indicated that psychological stress predicts less PA (behavioral inhibition) and/or exercise or more sedentary behavior (76.4 %). Both objective (i.e., life events) and subjective (i.e., distress) measures of stress related to reduced PA. Prospective studies investigating the effects of objective markers of stress nearly all agreed (six of seven studies) that stress has a negative effect on PA. This was true for research examining (a) PA at periods of objectively varying levels of stress (i.e., final examinations vs. a control time point) and (b) chronically stressed populations (e.g., caregivers, parents of children with a cancer diagnosis) that were less likely to be active than controls over time. Studies examining older adults (>50 years), cohorts with both men and women, and larger sample sizes (n > 100) were more likely

Plasmin cleaves fibrinogen and the human complement proteins C3b and C5 in the presence of Leptospira interrogans proteins: A new role of LigA and LigB in invasion and complement immune evasion.

Science.gov (United States)

Castiblanco-Valencia, Mónica Marcela; Fraga, Tatiana Rodrigues; Pagotto, Ana Helena; Serrano, Solange Maria de Toledo; Abreu, Patricia Antonia Estima; Barbosa, Angela Silva; Isaac, Lourdes

2016-05-01

Plasminogen is a single-chain glycoprotein found in human plasma as the inactive precursor of plasmin. When converted to proteolytically active plasmin, plasmin(ogen) regulates both complement and coagulation cascades, thus representing an important target for pathogenic microorganisms. Leptospira interrogans binds plasminogen, which is converted to active plasmin. Leptospiral immunoglobulin-like (Lig) proteins are surface exposed molecules that interact with extracellular matrix components and complement regulators, including proteins of the FH family and C4BP. In this work, we demonstrate that these multifunctional molecules also bind plasminogen through both N- and C-terminal domains. These interactions are dependent on lysine residues and are affected by ionic strength. Competition assays suggest that plasminogen does not share binding sites with C4BP or FH on Lig proteins at physiological molar ratios. Plasminogen bound to Lig proteins is converted to proteolytic active plasmin in the presence of urokinase-type plasminogen activator (uPA). Lig-bound plasmin is able to cleave the physiological substrates fibrinogen and the complement proteins C3b and C5. Taken together, our data point to a new role of LigA and LigB in leptospiral invasion and complement immune evasion. Plasmin(ogen) acquisition by these versatile proteins may contribute to Leptospira infection, favoring bacterial survival and dissemination inside the host. Copyright © 2016. Published by Elsevier GmbH.

Complement-mediated killing of Borrelia burgdorferi by nonimmune sera from sika deer.

Science.gov (United States)

Nelson, D R; Rooney, S; Miller, N J; Mather, T N

2000-12-01

Various species of cervid deer are the preferred hosts for adult, black-legged ticks (Ixodes scapularis and Ixodes pacificus) in the United States. Although frequently exposed to the agent of Lyme disease (Borrelia burgdorferi), these animals, for the most part, are incompetent as transmission reservoirs. We examined the borreliacidal activity of normal and B. burgdorferi-immune sera from sika deer (Cervus nippon) maintained in a laboratory setting and compared it to that of similar sera from reservoir-competent mice and rabbits. All normal deer sera (NDS) tested killed > 90% of B. burgdorferi cells. In contrast, normal mouse and rabbit sera killed feeding exhibited IFA titers of 1:256, whereas sera from mice and rabbits similarly exposed had titers of > 1:1,024. Heat treatment (56 C, 30 min) of NDS reduced borreliacidal activity, with complement-mediated killing. The chelators EGTA and EDTA were used to block the classical or both the classical and alternative complement pathways, respectively. Addition of 10 mM EGTA to NDS had a negligible effect on borreliacidal activity, with > 90% of the cells killed. Addition of 10 mM EDTA reduced the killing to approximately 30%, whereas the addition of Mg2+ (10 mM) restored borreliacidal activity to NDS. The addition of zymosan A, an activator of the alternative pathway, increased the survival of B. burgdorferi cells to approximately 80% in NDS. These data suggest that the alternative complement activation pathway plays a major role in the borreliacidal activity of NDS. Additionally, 10 mM EGTA had almost no effect on the killing activity of B. burgdorferi-exposed deer sera, suggesting that the classical pathway is not involved in Borrelia killing, even in sera from B. burgdorferi-exposed deer.

Neural activation in stress-related exhaustion

DEFF Research Database (Denmark)

Gavelin, Hanna Malmberg; Neely, Anna Stigsdotter; Andersson, Micael

2017-01-01

The primary purpose of this study was to investigate the association between burnout and neural activation during working memory processing in patients with stress-related exhaustion. Additionally, we investigated the neural effects of cognitive training as part of stress rehabilitation. Fifty...... association between burnout level and working memory performance was found, however, our findings indicate that frontostriatal neural responses related to working memory were modulated by burnout severity. We suggest that patients with high levels of burnout need to recruit additional cognitive resources...... to uphold task performance. Following cognitive training, increased neural activation was observed during 3-back in working memory-related regions, including the striatum, however, low sample size limits any firm conclusions....

Complement factor H deficiency and endocapillary glomerulonephritis due to paternal isodisomy and a novel factor H mutation

DEFF Research Database (Denmark)

Schejbel, L; Schmidt, I M; Kirchhoff, Eva Maria

2011-01-01

Complement factor H (CFH) is a regulator of the alternative complement activation pathway. Mutations in the CFH gene are associated with atypical hemolytic uremic syndrome, membranoproliferative glomerulonephritis type II and C3 glomerulonephritis. Here, we report a 6-month-old CFH-deficient child...

Aging causes decreased resistance to multiple stresses and a failure to activate specific stress response pathways

Science.gov (United States)

Bergsma, Alexis L.; Senchuk, Megan M.; Van Raamsdonk, Jeremy M.

2016-01-01

In this work, we examine the relationship between stress resistance and aging. We find that resistance to multiple types of stress peaks during early adulthood and then declines with age. To dissect the underlying mechanisms, we use C. elegans transcriptional reporter strains that measure the activation of different stress responses including: the heat shock response, mitochondrial unfolded protein response, endoplasmic reticulum unfolded protein response, hypoxia response, SKN-1-mediated oxidative stress response, and the DAF-16-mediated stress response. We find that the decline in stress resistance with age is at least partially due to a decreased ability to activate protective mechanisms in response to stress. In contrast, we find that any baseline increase in stress caused by the advancing age is too mild to detectably upregulate any of the stress response pathways. Further exploration of how worms respond to stress with increasing age revealed that the ability to mount a hormetic response to heat stress is also lost with increasing age. Overall, this work demonstrates that resistance to all types of stress declines with age. Based on our data, we speculate that the decrease in stress resistance with advancing age results from a genetically-programmed inactivation of stress response pathways, not accumulation of damage. PMID:27053445

Aging causes decreased resistance to multiple stresses and a failure to activate specific stress response pathways.

Science.gov (United States)

Dues, Dylan J; Andrews, Emily K; Schaar, Claire E; Bergsma, Alexis L; Senchuk, Megan M; Van Raamsdonk, Jeremy M

2016-04-01

In this work, we examine the relationship between stress resistance and aging. We find that resistance to multiple types of stress peaks during early adulthood and then declines with age. To dissect the underlying mechanisms, we use C. elegans transcriptional reporter strains that measure the activation of different stress responses including: the heat shock response, mitochondrial unfolded protein response, endoplasmic reticulum unfolded protein response, hypoxia response, SKN-1-mediated oxidative stress response, and the DAF-16-mediated stress response. We find that the decline in stress resistance with age is at least partially due to a decreased ability to activate protective mechanisms in response to stress. In contrast, we find that any baseline increase in stress caused by the advancing age is too mild to detectably upregulate any of the stress response pathways. Further exploration of how worms respond to stress with increasing age revealed that the ability to mount a hormetic response to heat stress is also lost with increasing age. Overall, this work demonstrates that resistance to all types of stress declines with age. Based on our data, we speculate that the decrease in stress resistance with advancing age results from a genetically-programmed inactivation of stress response pathways, not accumulation of damage.

The terminal complement complex is generated in chronic leg ulcers in the absence of protectin (CD59)

DEFF Research Database (Denmark)

Balslev, E; Thomsen, H K; Danielsen, L

1999-01-01

Loss of membrane complement regulators accompanied by complement activation is suggested to be involved in the pathophysiological processes leading to tissue damage in myocardial ischaemia. In the present study we have investigated whether the same phenomenon may occur in ischaemic and/or venous...... results suggest that loss of CD59 may enhance deposition of TCC and that complement-dependent inflammation may be an important factor in the tissue-damaging processes seen in chronic leg ulcers....

Does host complement kill Borrelia burgdorferi within ticks?

Science.gov (United States)

Rathinavelu, Sivaprakash; Broadwater, Anne; de Silva, Aravinda M

2003-02-01

The Lyme disease spirochete, Borrelia burgdorferi, inhabits the gut lumen of the tick vector. At this location the spirochete is exposed to host blood when a tick feeds. We report here on studies that were done with normal and complement-deficient (C3-knockout) mice to determine if the host complement system killed spirochetes within the vector. We found that spirochete numbers within feeding nymphs were not influenced by complement, most likely because host complement was inactivated within the vector. The Lyme disease outer surface protein A (OspA) vaccine is a transmission-blocking vaccine that targets spirochetes in the vector. In experiments with mice hyperimmunized with OspA, complement was not required to kill spirochetes within nymphs and to block transmission from nymphs to the vaccinated host. However, host complement did enhance the ability of OspA antibody to block larvae from acquiring spirochetes. Thus, the effects of OspA antibody on nymphal transmission and larval acquisition appear to be based on different mechanisms.

Hepatic macrophage complement receptor clearance function following injury.

Science.gov (United States)

Cuddy, B G; Loegering, D J; Blumenstock, F A; Shah, D M

1986-03-01

Previous work has demonstrated that in vivo hepatic macrophage complement receptor clearance function is depressed following thermal injury. The present study was carried out to determine if complement receptor function depression is associated with other states of depressed host defense. Hepatic complement receptor clearance function was determined from the hepatic uptake of rat erythrocytes coated with antierythrocyte IgM (EIgM) in rats. Receptor function was determined following cannulation of a carotid artery, laparotomy plus enterotomy, hemorrhagic shock, trauma, thermal injury, acute bacteremia, acute endotoxemia, and injection of erythrocyte stroma, gelatinized lipid emulsion, or colloidal carbon. Hepatic uptake of EIgM was depressed following each of these experimental interventions except arterial cannulation. This effect was shown not to be due to a decrease in hepatic blood flow or depletion of complement and was therefore due to a depression in hepatic macrophage complement receptor clearance function. Thus, impairment of hepatic macrophage complement receptor function is associated with several states of depressed host defense.

Stress field reconstruction in an active mudslide

Science.gov (United States)

Baroň, Ivo; Kernstocková, Markéta; Melichar, Rostislav

2017-07-01

Meso-scale structures from gravitational slope deformation observed in landslides and deep-seated gravitational slope failures are very similar to those of endogenous ones. Therefore we applied palaeostress analysis of fault-slip data for reconstructing the stress field of an active mudslide in Pechgraben, Austria. This complex compound landslide has developed in clayey colluvium and shale and was activated after a certain period of dormancy in June 2013. During the active motion on June 12, 2013, 73 fault-slip traces at 9 locations were measured within the landslide body. The heterogeneous fault-slip data were processed in term of palaeostresses, the reconstructed palaeostress tensor being characterized by the orientations of the three principal stress axes and the stress ratio (which provides the shape of the stress ellipsoid). The results of the palaeostress analysis were compared to airborne laser scan digital terrain models that revealed dynamics and superficial displacements of the moving mass prior and after our survey. The results were generally in good agreement with the observed landslide displacement pattern and with the anticipated stress regime according to Mohr-Coulomb failure criteria and Anderson's theory. The compressional regime was mostly registered at the toe in areas, where a compressional stress field is expected during previous mass-movement stages, or at margins loaded by subsequent landslide bodies from above. On the other hand, extension regimes were identified at the head scarps of secondary slides, subsequently on bulged ridges at the toe and in the zone of horst-and-graben structures in the lower central part of the main landslide body, where the basal slip surface probably had locally convex character. Strike-slip regimes, as well as oblique normal or oblique reverse regimes were observed at the lateral margins of the landslide bodies. The directions of principal stresses could be used as markers of landslide movement directions

Neuron-derived IgG protects neurons from complement-dependent cytotoxicity.

Science.gov (United States)

Zhang, Jie; Niu, Na; Li, Bingjie; McNutt, Michael A

2013-12-01

Passive immunity of the nervous system has traditionally been thought to be predominantly due to the blood-brain barrier. This concept must now be revisited based on the existence of neuron-derived IgG. The conventional concept is that IgG is produced solely by mature B lymphocytes, but it has now been found to be synthesized by murine and human neurons. However, the function of this endogenous IgG is poorly understood. In this study, we confirm IgG production by rat cortical neurons at the protein and mRNA levels, with 69.0 ± 5.8% of cortical neurons IgG-positive. Injury to primary-culture neurons was induced by complement leading to increases in IgG production. Blockage of neuron-derived IgG resulted in more neuronal death and early apoptosis in the presence of complement. In addition, FcγRI was found in microglia and astrocytes. Expression of FcγR I in microglia was increased by exposure to neuron-derived IgG. Release of NO from microglia triggered by complement was attenuated by neuron-derived IgG, and this attenuation could be reversed by IgG neutralization. These data demonstrate that neuron-derived IgG is protective of neurons against injury induced by complement and microglial activation. IgG appears to play an important role in maintaining the stability of the nervous system.

Activation of the hypothalamic-pituitary-adrenal stress axis induces cellular oxidative stress

Directory of Open Access Journals (Sweden)

Jereme G. Spiers

2015-01-01

Full Text Available Glucocorticoids released from the adrenal gland in response to stress-induced activation of the hypothalamic-pituitary-adrenal (HPA axis induce activity in the cellular reduction-oxidation (redox system. The redox system is a ubiquitous chemical mechanism allowing the transfer of electrons between donor/acceptors and target molecules during oxidative phosphorylation while simultaneously maintaining the overall cellular environment in a reduced state. The objective of this review is to present an overview of the current literature discussing the link between HPA axis-derived glucocorticoids and increased oxidative stress, particularly focussing on the redox changes observed in the hippocampus following glucocorticoid exposure.

[Renal risks of dietary complements: a forgotten cause].

Science.gov (United States)

Dori, Olympia; Humbert, Antoine; Burnier, Michel; Teta, Daniel

2014-02-26

The use of dietary complements like vitamins, minerals, trace elements, proteins, aminoacids and plant-derived agents is prevalent in the general population, in order to promote health and treat diseases. Dietary complements are considered as safe natural products and are easily available without prescription. However, these can lead to severe renal toxicity, especially in cases of unknown pre-existing chronic kidney disease (CKD). In particular, Chinese herbs including aristolochic acid, high doses of vitamine C, creatine and protein complements may lead to acute and chronic renal failure, sometimes irreversible. Dietary complement toxicity should be suspected in any case of unexplained renal impairement. In the case of pre-existing CKD, the use of potentially nephrotoxic dietary complements should be screened for.

The salivary scavenger and agglutinin (SALSA binds MBL and regulates the lectin pathway of complement in solution and on surfaces

Directory of Open Access Journals (Sweden)

Martin eParnov Reichhardt

2012-07-01

Full Text Available The scavenger receptor cysteine-rich (SRCR protein SALSA, also known as gp340, salivary agglutinin (SAG and deleted in malignant brain tumor 1 (DMBT1, is a 340 kDa glycoprotein expressed on mucosal surfaces and secreted into several body fluids. SALSA binds to a broad variety of microbes and endogenous ligands, such as complement factor C1q, surfactant proteins D and A (SP-D and SP-A and IgA. Our search for novel ligands of SALSA by direct protein-interaction studies led to the identification of mannan binding lectin (MBL as a new binding partner. We observed that surface-associated SALSA activates complement via binding of MBL. On the other hand, soluble SALSA was found to inhibit C. albicans-induced complement activation. Thus, SALSA has a dual complement regulatory function. It activates the lectin pathway when bound to a surface and inhibits it when free in the fluid-phase. These activities are mediated via a direct interaction with MBL.

Inertial effects on the stress generation of active fluids

Science.gov (United States)

Takatori, S. C.; Brady, J. F.

2017-09-01

Suspensions of self-propelled bodies generate a unique mechanical stress owing to their motility that impacts their large-scale collective behavior. For microswimmers suspended in a fluid with negligible particle inertia, we have shown that the virial swim stress is a useful quantity to understand the rheology and nonequilibrium behaviors of active soft matter systems. For larger self-propelled organisms such as fish, it is unclear how particle inertia impacts their stress generation and collective movement. Here we analyze the effects of finite particle inertia on the mechanical pressure (or stress) generated by a suspension of self-propelled bodies. We find that swimmers of all scales generate a unique swim stress and Reynolds stress that impact their collective motion. We discover that particle inertia plays a similar role as confinement in overdamped active Brownian systems, where the reduced run length of the swimmers decreases the swim stress and affects the phase behavior. Although the swim and Reynolds stresses vary individually with the magnitude of particle inertia, the sum of the two contributions is independent of particle inertia. This points to an important concept when computing stresses in computer simulations of nonequilibrium systems: The Reynolds and the virial stresses must both be calculated to obtain the overall stress generated by a system.

The membrane attack complex as an indicator of complement hyperactivation in type 2 diabetes mellitus

OpenAIRE

Elina Aleksandrovna Arakelova; Meri Robertovna Ovsepyan; Anna Surenovna Boyadzhyan; Arsen Artashesovich Arakelyan; Astkhik Artavazdovna Gevorkyan; Ashot Andreevich Mamikonyan

2011-01-01

Aim. Comparative analysis of the levels of the membrane attack complex (MAC) - an end product of complement activation, and of hemolytic activities of C1 and C3 complement components in sera of patients with diabetes mellitus 2 (DM2) and healthy subjects. Materials and methods. 37 DM2 patients (7 men, 26 women, mean age 58±9 years (M±б) and 37 healthy subjects without a family history of hereditary diabetes (17 men, 20 women, mean age 52±12 years). Serum MAC levels were measured by E...

Complement System in the Pathogenesis of Benign Lymphoepithelial Lesions of the Lacrimal Gland.

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Jing Li

Full Text Available We aimed to examine the potential involvement of local complement system gene expression in the pathogenesis of benign lymphoepithelial lesions (BLEL of the lacrimal gland.We collected data from 9 consecutive pathologically confirmed patients with BLEL of the lacrimal gland and 9 cases with orbital cavernous hemangioma as a control group, and adopted whole genome microarray to screen complement system-related differential genes, followed by RT-PCR verification and in-depth enrichment analysis (Gene Ontology analysis of the gene sets.The expression of 14 complement system-related genes in the pathologic tissue, including C2, C3, ITGB2, CR2, C1QB, CR1, ITGAX, CFP, C1QA, C4B|C4A, FANCA, C1QC, C3AR1 and CFHR4, were significantly upregulated while 7 other complement system-related genes, C5, CFI, CFHR1|CFH, CFH, CD55, CR1L and CFD were significantly downregulated in the lacrimal glands of BLEL patients. The microarray results were consistent with RT-PCR analysis results. Immunohistochemistry analysis of C3c and C1q complement component proteins in the resected tissue were positive in BLEL patients, while the control group had negative expression of these proteins. Gene ontology (GO analysis revealed that activation of the genes of complement system-mediated signaling pathways were the most enriched differential gene group in BLEL patients.Local expression of complement components is prominently abnormal in BLEL, and may well play a role in its pathogenesis.

Crosstalk between Complement and Toll-like Receptor Activation in Relation to Donor Brain Death and Renal Ischemia-Reperfusion Injury

NARCIS (Netherlands)

Damman, Jeffrey; Daha, Mohamed R.; van Son, Willem J.; Leuvenink, Henri G.; Ploeg, Rutger J.; Seelen, Marc A.

Two central pathways of innate immunity, complement and Toll-like receptors (TLRs), play an important role in the pathogenesis of renal injury inherent to kidney transplantation. Recent findings indicate close crosstalk between complement and TLR signaling pathways. It is suggested that mitogen

Activation and binding of opsonic fragments of C3 on encapsulated Cryptococcus neoformans by using an alternative complement pathway reconstituted from six isolated proteins.

Science.gov (United States)

Kozel, T R; Wilson, M A; Pfrommer, G S; Schlageter, A M

1989-07-01

Encapsulated Cryptococcus neoformans yeast cells are potent activators of the complement system. We examined the interaction of the yeast cells with an alternative complement pathway reconstituted from isolated factor D, factor B, factor H, factor I, C3, and properdin. Incubation of encapsulated cryptococci with the reconstituted pathway led to activation and binding of C3 fragments to the yeast cells that was quantitatively and qualitatively identical to that observed with normal human serum. Incubation with either normal serum or a mixture of isolated proteins led to binding of 4 x 10(7) to 5 x 10(7) C3 molecules to the yeast cells. The kinetics for activation and binding of C3 were identical, with maximum binding observed after a 20-min incubation. Immunoglobulin G was not needed for optimal activation kinetics. C3 fragments eluted from the yeast cells by treatment with hydroxylamine and subsequent analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated the presence primarily of iC3b on yeast cells incubated with either normal serum or the reconstituted pathway. Ultrastructural examination of the opsonized yeast cells showed that the cryptococcal capsule was the site for binding of C3 activated from normal serum or the reconstituted pathway, with a dense accumulation of C3 at the periphery of the capsule. Thus, incubation of encapsulated cryptococci in the reconstituted pathway led to deposition of opsonic complement fragments at a site that was appropriate for interaction with phagocyte receptors. Cryptococci opsonized with the reconstituted pathway showed a markedly enhanced interaction with cultured human monocytes compared with unopsonized yeast cells, indicating that the alternative pathway alone is opsonic for yeast cells. However, the results indicate that additional serum factors are needed for optimal opsonization of yeast cells because a 35% reduction in the number of cryptococci bound to macrophages was observed with

Complement factors C4 and C3 are down regulated in response to short term overfeeding in healthy young men

DEFF Research Database (Denmark)

Foghmar, Caroline; Brøns, Charlotte; Pilely, Katrine

2017-01-01

individuals only, while both groups had the same degree of hepatic insulin resistance after HFO. Viewing all individuals circulating levels of C4, C3, C3bc, TCC and complement activation capacity decreased paradoxically along the development of insulin resistance after HFO (P = 0.0015, P ...Insulin resistance is associated with high circulating level of complement factor C3. Animal studies suggest that improper complement activation mediates high-fat-diet-induced insulin resistance. Individuals born with low birth weight (LBW) are at increased risk of developing insulin resistance. We...... hypothesized that high-fat overfeeding (HFO) increase circulating C3 and induce complement activation in a birth weight differential manner. Twenty LBW and 26 normal birth weight (NBW) young men were studied using a randomised crossover design. Insulin resistance was measured after a control-diet and after 5...

Peroxisome biogenesis disorders: identification of a new complementation group distinct from peroxisome-deficient CHO mutants and not complemented by human PEX 13

NARCIS (Netherlands)

Shimozawa, N.; Suzuki, Y.; Zhang, Z.; Imamura, A.; Tsukamoto, T.; Osumi, T.; Tateishi, K.; Okumoto, K.; Fujiki, Y.; Orii, T.; Barth, P. G.; Wanders, R. J.; Kondo, N.

1998-01-01

Ten complementation groups of generalized peroxisome biogenesis disorders (PBD), (excluding rhizomelic chondrodysplasia punctata) have been identified using complementation analysis. Four of the genes involved have been identified using two different methods of (1) genetic functional complementation

Force Dynamics of Verb Complementation

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Jacek Woźny

2015-12-01

Full Text Available Force Dynamics of Verb Complementation The concepts of motion and force are both extensively discussed in cognitive linguistics literature. But they are discussed separately. The first usually in the context of ‘motion situations’ (Talmy, Slobin, Zlatev, the other as part of the Force Dynamics framework, which was developed by Talmy. The aim of this paper is twofold: first, to argue that the concepts of force and motion should not be isolated but considered as two inseparable parts of force-motion events. The second goal is to prove that the modified Force Dynamics (force-motion framework can be used for precise characterization of the verb complementation patterns. To this end, a random sample of 50 sentences containing the verb ‘went’ is analyzed, demonstrating the differences between the categories of intensive and intransitive complementation with respect to the linguistically coded parameters of force and motion.

Complement pathway biomarkers and age-related macular degeneration

Science.gov (United States)

Gemenetzi, M; Lotery, A J

2016-01-01

In the age-related macular degeneration (AMD) ‘inflammation model', local inflammation plus complement activation contributes to the pathogenesis and progression of the disease. Multiple genetic associations have now been established correlating the risk of development or progression of AMD. Stratifying patients by their AMD genetic profile may facilitate future AMD therapeutic trials resulting in meaningful clinical trial end points with smaller sample sizes and study duration. PMID:26493033

Physical activity and stress coping in the elderly

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Fernando de Andréa

2010-12-01

Full Text Available Objective: To analyze the value of a physical activity program on stress coping of the elderly. Methods: Intervention study with a group of 18 elderly people referred by the Geriatric Service of Hospital das Clínicas of the Universidade de São Paulo, who attended a supervised exercise program, evaluated by the human activity profile and the coping questionnaire. Results: In the coping and functional performance scales, increased stress coping capacity and improvement of daily activities were found after exposure to a physical activity program. Conclusions: The practice of supervised and regular physical activity, combining aerobic, resistance, stretching, and respiratory exercises, yields positive effects in the coping capacity and in the accomplishment of the daily activities.

Complement-related proteins control the flavivirus infection of Aedes aegypti by inducing antimicrobial peptides.

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Xiaoping Xiao

2014-04-01

Full Text Available The complement system functions during the early phase of infection and directly mediates pathogen elimination. The recent identification of complement-like factors in arthropods indicates that this system shares common ancestry in vertebrates and invertebrates as an immune defense mechanism. Thioester (TE-containing proteins (TEPs, which show high similarity to mammalian complement C3, are thought to play a key role in innate immunity in arthropods. Herein, we report that a viral recognition cascade composed of two complement-related proteins limits the flaviviral infection of Aedes aegypti. An A. aegypti macroglobulin complement-related factor (AaMCR, belonging to the insect TEP family, is a crucial effector in opposing the flaviviral infection of A. aegypti. However, AaMCR does not directly interact with DENV, and its antiviral effect requires an A. aegypti homologue of scavenger receptor-C (AaSR-C, which interacts with DENV and AaMCR simultaneously in vitro and in vivo. Furthermore, recognition of DENV by the AaSR-C/AaMCR axis regulates the expression of antimicrobial peptides (AMPs, which exerts potent anti-DENV activity. Our results both demonstrate the existence of a viral recognition pathway that controls the flaviviral infection by inducing AMPs and offer insights into a previously unappreciated antiviral function of the complement-like system in arthropods.

[The study on metabolic difference of human body affected by active stress and passive stress under special events].

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Guo, Guang-hong; Gu, Feng; Dong, Zhen-nan; Yuan, Xin-hong; Wang, Ling; Tian, Ya-ping

2010-05-01

To study the metabolic difference of body influenced by active stress and passive stress under special events. To detect serum multiple biochemistry index of 57 earthquake rescue medical team and 13 victims of a natural calamity in Wenchuan earthquake by using Hitachi 7600 automatic analyzer. Stress affected biochemistry index deeply. To compared with rescue medical team, the serum ADA, ALP and TG of victims increased obviously and TP, ALB, MAO, Cr, UA, K, Na, Cl, Ca, ApoA1 and HDL decreased obviously. Many biochemistry index have been changed under stress and it relate with stress extent. The human body function status was better in active stress than in passive stress.

A High-throughput Selection for Cellulase Catalysts Using Chemical Complementation

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Peralta-Yahya, Pamela; Carter, Brian T.; Lin, Hening; Tao, Haiyan; Cornish, Virginia W.

2010-01-01

Efficient enzymatic hydrolysis of lignocellulosic material remains one of the major bottlenecks to cost-effective conversion of biomass to ethanol. Improvement of glycosylhydrolases however is limited by existing medium-throughput screening technologies. Here, we report the first high-throughput selection for cellulase catalysts. This selection was developed by adapting chemical complementation to provide a growth assay for bond cleavage reactions. First, a URA3 counter selection was adapted to link chemical dimerizer activated gene transcription to cell death. Next, the URA3 counter selection was shown to detect cellulase activity based on cleavage of a tetrasaccharide chemical dimerizer substrate and decrease in expression of the toxic URA3 reporter. Finally, the utility of the cellulase selection was assessed by isolating cellulases with improved activity from a cellulase library created by family DNA shuffling. This application provides further evidence that chemical complementation can be readily adapted to detect different enzymatic activities for important chemical transformations for which no natural selection exists. Due to the large number of enzyme variants selections can test compared to existing medium-throughput screens for cellulases, this assay has the potential to impact the discovery of improved cellulases and other glycosylhydrolases for biomass conversion from libraries of cellulases created by mutagenesis or obtained from natural biodiversity. PMID:19053460

Induction of complement proteins in a mouse model for cerebral microvascular Aβ deposition

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DeFilippis Kelly

2007-09-01

Full Text Available Abstract The deposition of amyloid β-protein (Aβ in cerebral vasculature, known as cerebral amyloid angiopathy (CAA, is a common pathological feature of Alzheimer's disease and related disorders. In familial forms of CAA single mutations in the Aβ peptide have been linked to the increase of vascular Aβ deposits accompanied by a strong localized activation of glial cells and elevated expression of neuroinflammatory mediators including complement proteins. We have developed human amyloid-β precursor protein transgenic mice harboring two CAA Aβ mutations (Dutch E693Q and Iowa D694N that mimic the prevalent cerebral microvascular Aβ deposition observed in those patients, and the Swedish mutations (K670N/M671L to increase Aβ production. In these Tg-SwDI mice, we have reported predominant fibrillar Aβ along microvessels in the thalamic region and diffuse plaques in cortical region. Concurrently, activated microglia and reactive astrocytes have been detected primarily in association with fibrillar cerebral microvascular Aβ in this model. Here we show that three native complement components in classical and alternative complement pathways, C1q, C3, and C4, are elevated in Tg-SwDI mice in regions rich in fibrillar microvascular Aβ. Immunohistochemical staining of all three proteins was increased in thalamus, hippocampus, and subiculum, but not frontal cortex. Western blot analysis showed significant increases of all three proteins in the thalamic region (with hippocampus as well as the cortical region, except C3 that was below detection level in cortex. Also, in the thalamic region (with hippocampus, C1q and C3 mRNAs were significantly up-regulated. These complement proteins appeared to be expressed largely by activated microglial cells associated with the fibrillar microvascular Aβ deposits. Our findings demonstrate that Tg-SwDI mice exhibit elevated complement protein expression in response to fibrillar vascular Aβ deposition that is

Transient stress control of aeroengine disks based on active thermal management

International Nuclear Information System (INIS)

Ding, Shuiting; Wang, Ziyao; Li, Guo; Liu, Chuankai; Yang, Liu

2016-01-01

Highlights: • The essence of cooling in turbine system is a process of thermal management. • Active thermal management is proposed to control transient stress of disks. • The correlation between thermal load and transient stress of disks is built. • Stress level can be declined by actively adjusting the thermal load distribution. • Artificial temperature gradient can be used to counteract stress from rotating. - Abstract: The physical essence of cooling in the turbine system is a process of thermal management. In order to overcome the limits of passive thermal management based on thermal protection, the concept of active thermal management based on thermal load redistribution has been proposed. On this basis, this paper focuses on a near real aeroengine disk during a transient process and studies the stress control mechanism of active thermal management in transient conditions by a semi-analytical method. Active thermal management is conducted by imposing extra heating energy on the disk hub, which is represented by the coefficient of extra heat flow η. The results show that the transient stress level can be effectively controlled by actively adjusting the thermal load distribution. The decline ratio of the peak equivalent stress of the disk hub can be 9.0% for active thermal management load condition (η = 0.2) compared with passive condition (η = 0), even at a rotation speed of 10,000 r/min. The reason may be that the temperature distribution of the disk turns into an artificial V-shape because of the extra heating energy on the hub, and the resulting thermal stresses induced by the negative temperature gradients counteract parts of the stress from rotating.

Methylation of the phosphate oxygen moiety of phospholipid-methoxy(polyethylene glycol) conjugate prevents PEGylated liposome-mediated complement activation and anaphylatoxin production

DEFF Research Database (Denmark)

Moghimi, S.M.; Hamad, I.; Andresen, Thomas Lars

2006-01-01

Methoxy(polyethylene glycol), mPEG, -grafted liposomes are known to exhibit prolonged circulation time in the blood, but their infusion into a substantial percentage of human subjects triggers immediate non-IgE-mediated hypersensitivity reactions. These reactions are strongly believed to arise from...... to PEGylated liposome-mediated complement activation. Our findings provide a rational conceptual basis for development of safer vesicles for site-specific drug delivery and controlled release at pathological sites....

The Lectin Complement Pathway in Patients with Necrotizing Soft Tissue Infection

DEFF Research Database (Denmark)

Hansen, Marco Bo; Rasmussen, Lars S; Pilely, Katrine

2016-01-01

BACKGROUND: Mannose-binding lectin (MBL) and ficolins are pattern recognition molecules (PRMs) that play an important role during infection through activation of the lectin complement pathway. We assessed whether plasma PRM levels were associated with mortality in patients with necrotizing soft t...

Triatoma infestans Calreticulin: Gene Cloning and Expression of a Main Domain That Interacts with the Host Complement System.

Science.gov (United States)

Weinberger, Katherine; Collazo, Norberto; Aguillón, Juan Carlos; Molina, María Carmen; Rosas, Carlos; Peña, Jaime; Pizarro, Javier; Maldonado, Ismael; Cattan, Pedro E; Apt, Werner; Ferreira, Arturo

2017-02-08

Triatoma infestans is an important hematophagous vector of Chagas disease, a neglected chronic illness affecting approximately 6 million people in Latin America. Hematophagous insects possess several molecules in their saliva that counteract host defensive responses. Calreticulin (CRT), a multifunctional protein secreted in saliva, contributes to the feeding process in some insects. Human CRT (HuCRT) and Trypanosoma cruzi CRT (TcCRT) inhibit the classical pathway of complement activation, mainly by interacting through their central S domain with complement component C1. In previous studies, we have detected CRT in salivary gland extracts from T. infestans We have called this molecule TiCRT. Given that the S domain is responsible for C1 binding, we have tested its role in the classical pathway of complement activation in vertebrate blood. We have cloned and characterized the complete nucleotide sequence of CRT from T. infestans , and expressed its S domain. As expected, this S domain binds to human C1 and, as a consequence, it inhibits the classical pathway of complement, at its earliest stage of activation, namely the generation of C4b. Possibly, the presence of TiCRT in the salivary gland represents an evolutionary adaptation in hematophagous insects to control a potential activation of complement proteins, present in the massive blood meal that they ingest, with deleterious consequences at least on the anterior digestive tract of these insects. © The American Society of Tropical Medicine and Hygiene.

Activation of Inflammatory and Pro-Thrombotic Pathways in Acute Stress Cardiomyopathy

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Timothy P. Fitzgibbons

2017-08-01

Full Text Available Stress cardiomyopathy (SCM is a unique cardiac disorder that more often occurs in women. SCM presents in a similar fashion as acute myocardial infarction (AMI, with chest pain, ECG changes, and congestive heart failure. The primary distinguishing feature is the absence of thrombotic coronary occlusion in SCM. How this reduction in cardiac function occurs in the absence of coronary occlusion remains unknown. Therefore, we tested the hypothesis that a targeted proteomic comparison of patients with acute SCM and AMI might identify relevant mechanistic differences. Blood was drawn in normal controls (n = 6, women with AMI (n = 12, or women with acute SCM (n = 15. Two-week follow-up samples were available in AMI (n = 4 and SCM patients (n = 11. Relative concentrations of 1,310 serum proteins were measured in each of the 48 samples using the SOMAscan assay. Women with AMI had greater myocyte necrosis, as reflected by a higher peak troponin I concentration (AMI 32.03 ± 29.46 vs. SCM 2.68 ± 2.6 ng/ml, p < 0.05. AMI and SCM patients had equivalent reductions in left ventricular ejection fraction [LVEF (% 39 ± 12 vs. 37 ± 12, p = 0.479]. In follow-up, women with SCM had a greater improvement in cardiac function [LVEF (% 60 ± 7 vs. 45 ± 13, p < 0.001]. No differentially expressed proteins were detected (absolute log2-fold change >1; q < 0.05 between AMI and SCM in the acute or recovery phase. However, when we compared normal controls to patients with AMI, there was differential expression of 35 proteins. When we compared normal controls to patients with SCM, 45 proteins were differentially expressed. In comparison to normal controls, biological processes such as complement, coagulation, and inflammation were activated in both AMI and SCM. There were four proteins that showed a non-significant trend to be increased in acute SCM vs. AMI (netrin-1, follistatin-like 3, kallikrein 7

Regulation of Cre recombinase by ligand-induced complementation of inactive fragments.

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Jullien, Nicolas; Sampieri, François; Enjalbert, Alain; Herman, Jean-Paul

2003-11-01

Cre recombinase is extensively used to engineer the genome of experimental animals. However, its usefulness is still limited by the lack of an efficient temporal control over its activity. To overcome this, we have developed DiCre, a regulatable fragment complementation system for Cre. The enzyme was split into two moieties that were fused to FKBP12 (FK506-binding protein) and FRB (binding domain of the FKBP12-rapamycin-associated protein), respectively. These can be efficiently heterodimerized by rapamycin. Several variants, based on splitting Cre at different sites and using different linker peptides, were tested in an indicator cell line. The fusion proteins, taken separately, had no recombinase activity. Stable transformants, co-expressing complementing fragments based on splitting Cre between Asn59 and Asn60, displayed low background activity affecting 0.05-0.4% of the cells. Rapamycin induced a rapid recombination, reaching 100% by 48-72 h, with an EC50 of 0.02 nM. Thus, ligand-induced dimerization can efficiently regulate Cre, and should be useful to achieve a tight temporal control of its activity, such as in the case of the creation of conditional knock-out animals.

Amblyomma americanum tick calreticulin binds C1q but does not inhibit activation of the classical complement cascade.

Science.gov (United States)

Kim, Tae Kwon; Ibelli, Adriana Mércia Guaratini; Mulenga, Albert

2015-02-01

In this study we characterized Amblyomma americanum (Aam) tick calreticulin (CRT) homolog in tick feeding physiology. In nature, different tick species can be found feeding on the same animal host. This suggests that different tick species found feeding on the same host can modulate the same host anti-tick defense pathways to successfully feed. From this perspective it's plausible that different tick species can utilize universally conserved proteins such as CRT to regulate and facilitate feeding. CRT is a multi-functional protein found in most taxa that is injected into the vertebrate host during tick feeding. Apart from it's current use as a biomarker for human tick bites, role(s) of this protein in tick feeding physiology have not been elucidated. Here we show that annotated functional CRT amino acid motifs are well conserved in tick CRT. However our data show that despite high amino acid identity levels to functionally characterized CRT homologs in other organisms, AamCRT is apparently functionally different. Pichia pastoris expressed recombinant (r) AamCRT bound C1q, the first component of the classical complement system, but it did not inhibit activation of this pathway. This contrast with reports of other parasite CRT that inhibited activation of the classical complement pathway through sequestration of C1q. Furthermore rAamCRT did not bind factor Xa in contrast to reports of parasite CRT binding factor Xa, an important protease in the blood clotting system. Consistent with this observation, rAamCRT did not affect plasma clotting or platelet aggregation. We discuss our findings in the context of tick feeding physiology.

Specific alterations in complement protein activity of little brown myotis (Myotis lucifugus hibernating in white-nose syndrome affected sites.

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Marianne S Moore

Full Text Available White-nose syndrome (WNS is the most devastating condition ever reported for hibernating bats, causing widespread mortality in the northeastern United States. The syndrome is characterized by cutaneous lesions caused by a recently identified psychrophilic and keratinophylic fungus (Geomyces destructans, depleted fat reserves, atypical behavior, and damage to wings; however, the proximate cause of mortality is still uncertain. To assess relative levels of immunocompetence in bats hibernating in WNS-affected sites compared with levels in unaffected bats, we describe blood plasma complement protein activity in hibernating little brown myotis (Myotis lucifugus based on microbicidal competence assays using Escherichia coli, Staphylococcus aureus and Candida albicans. Blood plasma from bats collected during mid-hibernation at WNS-affected sites had higher bactericidal ability against E. coli and S. aureus, but lower fungicidal ability against C. albicans when compared with blood plasma from bats collected at unaffected sites. Within affected sites during mid-hibernation, we observed no difference in microbicidal ability between bats displaying obvious fungal infections compared to those without. Bactericidal ability against E. coli decreased significantly as hibernation progressed in bats collected from an affected site. Bactericidal ability against E. coli and fungicidal ability against C. albicans were positively correlated with body mass index (BMI during late hibernation. We also compared complement activity against the three microbes within individuals and found that the ability of blood plasma from hibernating M. lucifugus to lyse microbial cells differed as follows: E. coli>S. aureus>C. albicans. Overall, bats affected by WNS experience both relatively elevated and reduced innate immune responses depending on the microbe tested, although the cause of observed immunological changes remains unknown. Additionally, considerable trade-offs may exist

Specific alterations in complement protein activity of little brown myotis (Myotis lucifugus) hibernating in white-nose syndrome affected sites.

Science.gov (United States)

Moore, Marianne S; Reichard, Jonathan D; Murtha, Timothy D; Zahedi, Bita; Fallier, Renee M; Kunz, Thomas H

2011-01-01

White-nose syndrome (WNS) is the most devastating condition ever reported for hibernating bats, causing widespread mortality in the northeastern United States. The syndrome is characterized by cutaneous lesions caused by a recently identified psychrophilic and keratinophylic fungus (Geomyces destructans), depleted fat reserves, atypical behavior, and damage to wings; however, the proximate cause of mortality is still uncertain. To assess relative levels of immunocompetence in bats hibernating in WNS-affected sites compared with levels in unaffected bats, we describe blood plasma complement protein activity in hibernating little brown myotis (Myotis lucifugus) based on microbicidal competence assays using Escherichia coli, Staphylococcus aureus and Candida albicans. Blood plasma from bats collected during mid-hibernation at WNS-affected sites had higher bactericidal ability against E. coli and S. aureus, but lower fungicidal ability against C. albicans when compared with blood plasma from bats collected at unaffected sites. Within affected sites during mid-hibernation, we observed no difference in microbicidal ability between bats displaying obvious fungal infections compared to those without. Bactericidal ability against E. coli decreased significantly as hibernation progressed in bats collected from an affected site. Bactericidal ability against E. coli and fungicidal ability against C. albicans were positively correlated with body mass index (BMI) during late hibernation. We also compared complement activity against the three microbes within individuals and found that the ability of blood plasma from hibernating M. lucifugus to lyse microbial cells differed as follows: E. coli>S. aureus>C. albicans. Overall, bats affected by WNS experience both relatively elevated and reduced innate immune responses depending on the microbe tested, although the cause of observed immunological changes remains unknown. Additionally, considerable trade-offs may exist between energy

Mast Cell Activation in Brain Injury, Stress, and Post-traumatic Stress Disorder and Alzheimer's Disease Pathogenesis.

Science.gov (United States)

Kempuraj, Duraisamy; Selvakumar, Govindhasamy P; Thangavel, Ramasamy; Ahmed, Mohammad E; Zaheer, Smita; Raikwar, Sudhanshu P; Iyer, Shankar S; Bhagavan, Sachin M; Beladakere-Ramaswamy, Swathi; Zaheer, Asgar

2017-01-01

Mast cells are localized throughout the body and mediate allergic, immune, and inflammatory reactions. They are heterogeneous, tissue-resident, long-lived, and granulated cells. Mast cells increase their numbers in specific site in the body by proliferation, increased recruitment, increased survival, and increased rate of maturation from its progenitors. Mast cells are implicated in brain injuries, neuropsychiatric disorders, stress, neuroinflammation, and neurodegeneration. Brain mast cells are the first responders before microglia in the brain injuries since mast cells can release prestored mediators. Mast cells also can detect amyloid plaque formation during Alzheimer's disease (AD) pathogenesis. Stress conditions activate mast cells to release prestored and newly synthesized inflammatory mediators and induce increased blood-brain barrier permeability, recruitment of immune and inflammatory cells into the brain and neuroinflammation. Stress induces the release of corticotropin-releasing hormone (CRH) from paraventricular nucleus of hypothalamus and mast cells. CRH activates glial cells and mast cells through CRH receptors and releases neuroinflammatory mediators. Stress also increases proinflammatory mediator release in the peripheral systems that can induce and augment neuroinflammation. Post-traumatic stress disorder (PTSD) is a traumatic-chronic stress related mental dysfunction. Currently there is no specific therapy to treat PTSD since its disease mechanisms are not yet clearly understood. Moreover, recent reports indicate that PTSD could induce and augment neuroinflammation and neurodegeneration in the pathogenesis of neurodegenerative diseases. Mast cells play a crucial role in the peripheral inflammation as well as in neuroinflammation due to brain injuries, stress, depression, and PTSD. Therefore, mast cells activation in brain injury, stress, and PTSD may accelerate the pathogenesis of neuroinflammatory and neurodegenerative diseases including AD. This

Mast Cell Activation in Brain Injury, Stress, and Post-traumatic Stress Disorder and Alzheimer's Disease Pathogenesis

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Duraisamy Kempuraj

2017-12-01

Full Text Available Mast cells are localized throughout the body and mediate allergic, immune, and inflammatory reactions. They are heterogeneous, tissue-resident, long-lived, and granulated cells. Mast cells increase their numbers in specific site in the body by proliferation, increased recruitment, increased survival, and increased rate of maturation from its progenitors. Mast cells are implicated in brain injuries, neuropsychiatric disorders, stress, neuroinflammation, and neurodegeneration. Brain mast cells are the first responders before microglia in the brain injuries since mast cells can release prestored mediators. Mast cells also can detect amyloid plaque formation during Alzheimer's disease (AD pathogenesis. Stress conditions activate mast cells to release prestored and newly synthesized inflammatory mediators and induce increased blood-brain barrier permeability, recruitment of immune and inflammatory cells into the brain and neuroinflammation. Stress induces the release of corticotropin-releasing hormone (CRH from paraventricular nucleus of hypothalamus and mast cells. CRH activates glial cells and mast cells through CRH receptors and releases neuroinflammatory mediators. Stress also increases proinflammatory mediator release in the peripheral systems that can induce and augment neuroinflammation. Post-traumatic stress disorder (PTSD is a traumatic-chronic stress related mental dysfunction. Currently there is no specific therapy to treat PTSD since its disease mechanisms are not yet clearly understood. Moreover, recent reports indicate that PTSD could induce and augment neuroinflammation and neurodegeneration in the pathogenesis of neurodegenerative diseases. Mast cells play a crucial role in the peripheral inflammation as well as in neuroinflammation due to brain injuries, stress, depression, and PTSD. Therefore, mast cells activation in brain injury, stress, and PTSD may accelerate the pathogenesis of neuroinflammatory and neurodegenerative diseases

Multilayered control of peroxisomal activity upon salt stress in Saccharomyces cerevisiae.

Science.gov (United States)

Manzanares-Estreder, Sara; Espí-Bardisa, Joan; Alarcón, Benito; Pascual-Ahuir, Amparo; Proft, Markus

2017-06-01

Peroxisomes are dynamic organelles and the sole location for fatty acid β-oxidation in yeast cells. Here, we report that peroxisomal function is crucial for the adaptation to salt stress, especially upon sugar limitation. Upon stress, multiple layers of control regulate the activity and the number of peroxisomes. Activated Hog1 MAP kinase triggers the induction of genes encoding enzymes for fatty acid activation, peroxisomal import and β-oxidation through the Adr1 transcriptional activator, which transiently associates with genes encoding fatty acid metabolic enzymes in a stress- and Hog1-dependent manner. Moreover, Na + and Li + stress increases the number of peroxisomes per cell in a Hog1-independent manner, which depends instead of the retrograde pathway and the dynamin related GTPases Dnm1 and Vps1. The strong activation of the Faa1 fatty acyl-CoA synthetase, which specifically localizes to lipid particles and peroxisomes, indicates that adaptation to salt stress requires the enhanced mobilization of fatty acids from internal lipid stores. Furthermore, the activation of mitochondrial respiration during stress depends on peroxisomes, mitochondrial acetyl-carnitine uptake is essential for salt resistance and the number of peroxisomes attached to the mitochondrial network increases during salt adaptation, which altogether indicates that stress-induced peroxisomal β-oxidation triggers enhanced respiration upon salt shock. © 2017 John Wiley & Sons Ltd.

Genetic and Biochemical Analysis of Intragenic Complementation Events among Nitrate Reductase Apoenzyme-Deficient Mutants of Nicotiana Plumbaginifolia

OpenAIRE

Pelsy, F.; Gonneau, M.

1991-01-01

Intragenic complementation has been observed between apoenzyme nitrate reductase-deficient mutants (nia) of Nicotiana plumbaginifolia. In vivo as in vitro, the NADH-nitrate reductase (NR) activity in plants heterozygous for two different nia alleles was lower than in the wild type plant, but the plants were able to grow on nitrate as a sole nitrogen source. NR activity, absent in extracts of homozygous nia mutants was restored by mixing extracts from two complementing nia mutants. These obser...

Kupffer cell complement receptor clearance function and host defense.

Science.gov (United States)

Loegering, D J

1986-01-01

Kupffer cells are well known to be important for normal host defense function. The development of methods to evaluate the in vivo function of specific receptors on Kupffer cells has made it possible to assess the role of these receptors in host defense. The rationale for studying complement receptors is based on the proposed important role of these receptors in host defense and on the observation that the hereditary deficiency of a complement receptor is associated with recurrent severe bacterial infections. The studies reviewed here demonstrate that forms of injury that are associated with depressed host defense including thermal injury, hemorrhagic shock, trauma, and surgery also cause a decrease in complement receptor clearance function. This decrease in Kupffer cell receptor clearance function was shown not to be the result of depressed hepatic blood flow or depletion of complement components. Complement receptor function was also depressed following the phagocytosis of particulates that are known to depress Kupffer cell host defense function. Endotoxemia and bacteremia also were associated with a depression of complement receptor function. Complement receptor function was experimentally depressed in uninjured animals by the phagocytosis of IgG-coated erythrocytes. There was a close association between the depression of complement receptor clearance function and increased susceptibility to the lethal effects of endotoxin and bacterial infection. These studies support the hypotheses that complement receptors on Kupffer cells are important for normal host defense and that depression of the function of these receptors impairs host defense.

Autoantibodies against complement components in systemic lupus erythematosus - role in the pathogenesis and clinical manifestations.

Science.gov (United States)

Hristova, M H; Stoyanova, V S

2017-12-01

Many complement structures and a number of additional factors, i.e. autoantibodies, receptors, hormones and cytokines, are implicated in the complex pathogenesis of systemic lupus erythematosus. Genetic defects in the complement as well as functional deficiency due to antibodies against its components lead to different pathological conditions, usually clinically presented. Among them hypocomplementemic urticarial vasculitis, different types of glomerulonephritis as dense deposit disease, IgA nephropathy, atypical haemolytic uremic syndrome and lupus nephritis are very common. These antibodies cause conformational changes leading to pathological activation or inhibition of complement with organ damage and/or limited capacity of the immune system to clear immune complexes and apoptotic debris. Finally, we summarize the role of complement antibodies in the pathogenesis of systemic lupus erythematosus and discuss the mechanism of some related clinical conditions such as infections, thyroiditis, thrombosis, acquired von Willebrand disease, etc.

Complement pathways and meningococcal disease : diagnostic aspects

DEFF Research Database (Denmark)

Sjöholm, A G; Truedsson, L; Jensenius, Jens Christian

2001-01-01

Complement is an immunological effector system that bridges innate and acquired immunity in several ways. There is a striking association between susceptibility to meningococcal disease and various forms of complement deficiency (1,2). In defense against bacterial infection, the most important fu...

Serum complement changes during double-blind food challenges in children with a history of food sensitivity.

Science.gov (United States)

Martin, M E; Guthrie, L A; Bock, S A

1984-04-01

Serum levels of C3, C4, factor B, properdin, total hemolytic complement and alternative-pathway hemolytic activity were measured before and after double-blind food challenge in 23 children with impressive histories of adverse reactions to foods. The 23 subjects had 11 positive food challenges and 12 negative food challenges. Nine patients with reagin-mediated positive food challenges showed increases in all six complement assays after double-blind food challenge, while the group with negative food challenges showed decreases in five of the six assays. The difference between the two groups for complement changes after double-blind food challenge was significant only for the alternative-pathway assay. Individual subject analysis revealed markedly heterogeneous changes in direction and magnitude within both groups for all complement assays. Therefore, it is concluded that measurement of serum complement levels is not a useful test for the clinical evaluation of a patient with suspected food sensitivity.

A Revised Mechanism for the Activation of Complement C3 to C3b

Science.gov (United States)

Rodriguez, Elizabeth; Nan, Ruodan; Li, Keying; Gor, Jayesh; Perkins, Stephen J.

2015-01-01

The solution structure of complement C3b is crucial for the understanding of complement activation and regulation. C3b is generated by the removal of C3a from C3. Hydrolysis of the C3 thioester produces C3u, an analog of C3b. C3b cleavage results in C3c and C3d (thioester-containing domain; TED). To resolve functional questions in relation to C3b and C3u, analytical ultracentrifugation and x-ray and neutron scattering studies were used with C3, C3b, C3u, C3c, and C3d, using the wild-type allotype with Arg102. In 50 mm NaCl buffer, atomistic scattering modeling showed that both C3b and C3u adopted a compact structure, similar to the C3b crystal structure in which its TED and macroglobulin 1 (MG1) domains were connected through the Arg102–Glu1032 salt bridge. In physiological 137 mm NaCl, scattering modeling showed that C3b and C3u were both extended in structure, with the TED and MG1 domains now separated by up to 6 nm. The importance of the Arg102–Glu1032 salt bridge was determined using surface plasmon resonance to monitor the binding of wild-type C3d(E1032) and mutant C3d(A1032) to immobilized C3c. The mutant did not bind, whereas the wild-type form did. The high conformational variability of TED in C3b in physiological buffer showed that C3b is more reactive than previously thought. Because the Arg102-Glu1032 salt bridge is essential for the C3b-Factor H complex during the regulatory control of C3b, the known clinical associations of the major C3S (Arg102) and disease-linked C3F (Gly102) allotypes of C3b were experimentally explained for the first time. PMID:25488663

Characterization of vanadate-dependent NADH oxidation activity and isolation of yeast DNA which complements a class 1 vanadate resistance mutation

International Nuclear Information System (INIS)

Minasi, L.E.

1989-01-01

A vanadate-dependent NADH oxidation activity has been characterized in plasma membranes from the yeast S cerevisiae. NADH oxidation activity was maximally stimulated at pH 5.0 in phosphate buffer. NADH oxidation was not dependent on the concentration of plasma membranes. The vanadate-dependent NADH oxidation activity was abolished under anaerobic conditions and the concomitant uptake of oxygen occurred during NADH oxidation. The activity was inhibited by superoxide dismutase and stimulated by the presence of paraquat. These results indicate that the vanadate stimulation of NADH oxidation in yeast plasma membranes occurs as a result of the vanadate-dependent oxidation of NADH by superoxide, generated by a plasma membrane NADH oxidase. 51 V-NMR results indicated that a phosphate-vanadate anhydride was the stimulatory species in pH 5.0 and pH 7.0 phosphate buffer. Yeast DNA has been isolated which complements a class 1 vanadate resistance mutation

Reduction in erythrocyte-bound complement activation products and titres of anti-C1q antibodies associate with clinical improvement in systemic lupus erythematosus.

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Buyon, Jill; Furie, Richard; Putterman, Chaim; Ramsey-Goldman, Rosalind; Kalunian, Kenneth; Barken, Derren; Conklin, John; Dervieux, Thierry

2016-01-01

The relationship between cell-bound complement activation products (CB-CAPs: EC4d, EC3d), anti-C1q, soluble complement C3/C4 and disease activity in systemic lupus erythematosus (SLE) was evaluated. Per protocol, at baseline all SLE subjects enrolled in this longitudinal study presented with active disease and elevated CB-CAPs. At each monthly visit, the non-serological (ns) Safety of Estrogens in Lupus Erythematosus: National Assessment (SELENA-SLEDAI) and the British Isles Lupus Assessment Group (BILAG)-2004 index scores were determined as was a random urinary protein to creatinine ratio (uPCR). Short-form 36 (SF-36) questionnaires were also collected. All soluble markers were determined using immunoassays, while EC4d and EC3d were determined using flow cytometry. Statistical analysis consisted of linear mixed models with random intercept and fixed slopes. A total of 36 SLE subjects (mean age 34 years; 94% female) were enrolled and evaluated monthly for an average 11 visits per subject. Clinical improvements were observed during the study, with significant decreases in ns-SELENA-SLEDAI scores, BILAG-2004 index scores and uPCR, and increases in all domains of SF-36 (pimprovements in at least six out of the eight domains of SF-36 and outperformed C3/C4. Anti-dsDNA titres did not correlate with changes in disease activity. These data indicate that CB-CAPs and anti-C1q are helpful in monitoring patients with SLE.

Agrobacterium rhizogenes transformed soybean roots differ in their nodulation and nitrogen fixation response to genistein and salt stress.

Science.gov (United States)

Dolatabadian, Aria; Modarres Sanavy, Seyed Ali Mohammad; Ghanati, Faezeh; Gresshoff, Peter M

2013-07-01

We evaluated response differences of normal and transformed (so-called 'hairy') roots of soybean (Glycine max L. (Merr.), cv L17) to the Nod-factor inducing isoflavone genistein and salinity by quantifying growth, nodulation, nitrogen fixation and biochemical changes. Composite soybean plants were generated using Agrobacterium rhizogenes-mediated transformation of non-nodulating mutant nod139 (GmNFR5α minus) with complementing A. rhizogenes K599 carrying the wild-type GmNFR5α gene under control of the constitutive CaMV 35S promoter. We used genetic complementation for nodulation ability as only nodulated roots were scored. After hairy root emergence, primary roots were removed and composite plants were inoculated with Bradyrhizobium japonicum (strain CB1809) pre-induced with 10 μM genistein and watered with NaCl (0, 25, 50 and 100 mM). There were significant differences between hairy roots and natural roots in their responses to salt stress and genistein application. In addition, there were noticeable nodulation and nitrogen fixation differences. Composite plants had better growth, more root volume and chlorophyll as well as more nodules and higher nitrogenase activity (acetylene reduction) compared with natural roots. Decreased lipid peroxidation, proline accumulation and catalase/peroxidase activities were found in 'hairy' roots under salinity stress. Genistein significantly increased nodulation and nitrogen fixation and improved roots and shoot growth. Although genistein alleviated lipid peroxidation under salinity stress, it had no significant effect on the activity of antioxidant enzymes. In general, composite plants were more competitive in growth, nodulation and nitrogen fixation than normal non-transgenic even under salinity stress conditions.

An Induced Pluripotent Stem Cell Patient Specific Model of Complement Factor H (Y402H) Polymorphism Displays Characteristic Features of Age-Related Macular Degeneration and Indicates a Beneficial Role for UV Light Exposure.

Science.gov (United States)

Hallam, Dean; Collin, Joseph; Bojic, Sanja; Chichagova, Valeria; Buskin, Adriana; Xu, Yaobo; Lafage, Lucia; Otten, Elsje G; Anyfantis, George; Mellough, Carla; Przyborski, Stefan; Alharthi, Sameer; Korolchuk, Viktor; Lotery, Andrew; Saretzki, Gabriele; McKibbin, Martin; Armstrong, Lyle; Steel, David; Kavanagh, David; Lako, Majlinda

2017-11-01

Age-related macular degeneration (AMD) is the most common cause of blindness, accounting for 8.7% of all blindness globally. Vision loss is caused ultimately by apoptosis of the retinal pigment epithelium (RPE) and overlying photoreceptors. Treatments are evolving for the wet form of the disease; however, these do not exist for the dry form. Complement factor H polymorphism in exon 9 (Y402H) has shown a strong association with susceptibility to AMD resulting in complement activation, recruitment of phagocytes, RPE damage, and visual decline. We have derived and characterized induced pluripotent stem cell (iPSC) lines from two subjects without AMD and low-risk genotype and two patients with advanced AMD and high-risk genotype and generated RPE cells that show local secretion of several proteins involved in the complement pathway including factor H, factor I, and factor H-like protein 1. The iPSC RPE cells derived from high-risk patients mimic several key features of AMD including increased inflammation and cellular stress, accumulation of lipid droplets, impaired autophagy, and deposition of "drüsen"-like deposits. The low- and high-risk RPE cells respond differently to intermittent exposure to UV light, which leads to an improvement in cellular and functional phenotype only in the high-risk AMD-RPE cells. Taken together, our data indicate that the patient specific iPSC model provides a robust platform for understanding the role of complement activation in AMD, evaluating new therapies based on complement modulation and drug testing. Stem Cells 2017;35:2305-2320. © 2017 The Authors Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

The Scl1 protein of M6-type group A Streptococcus binds the human complement regulatory protein, factor H, and inhibits the alternative pathway of complement.

Science.gov (United States)

Caswell, Clayton C; Han, Runlin; Hovis, Kelley M; Ciborowski, Pawel; Keene, Douglas R; Marconi, Richard T; Lukomski, Slawomir

2008-02-01

Non-specific activation of the complement system is regulated by the plasma glycoprotein factor H (FH). Bacteria can avoid complement-mediated opsonization and phagocytosis through acquiring FH to the cell surface. Here, we characterize an interaction between the streptococcal collagen-like protein Scl1.6 of M6-type group A Streptococcus (GAS) and FH. Using affinity chromatography with immobilized recombinant Scl1.6 protein, we co-eluted human plasma proteins with molecular weight of 155 kDa, 43 kDa and 38 kDa. Mass spectrometry identified the 155 kDa band as FH and two other bands as isoforms of the FH-related protein-1. The identities of all three bands were confirmed by Western immunoblotting with specific antibodies. Structure-function relation studies determined that the globular domain of the Scl1.6 variant specifically binds FH while fused to collagenous tails of various lengths. This binding is not restricted to Scl1.6 as the phylogenetically linked Scl1.55 variant also binds FH. Functional analyses demonstrated the cofactor activity of the rScl1.6-bound FH for factor I-mediated cleavage of C3b. Finally, purified FH bound to the Scl1.6 protein present in the cell wall material obtained from M6-type GAS. In conclusion, we have identified a functional interaction between Scl1 and plasma FH, which may contribute to GAS evasion of complement-mediated opsonization and phagocytosis.

A targeted complement-dependent strategy to improve the outcome of mAb therapy, and characterization in a murine model of metastatic cancer

Science.gov (United States)

Elvington, Michelle; Huang, Yuxiang; Morgan, B. Paul; Qiao, Fei; van Rooijen, Nico; Atkinson, Carl

2012-01-01

Complement inhibitors expressed on tumor cells provide an evasion mechanism against mAb therapy and may modulate the development of an acquired antitumor immune response. Here we investigate a strategy to amplify mAb-targeted complement activation on a tumor cell, independent of a requirement to target and block complement inhibitor expression or function, which is difficult to achieve in vivo. We constructed a murine fusion protein, CR2Fc, and demonstrated that the protein targets to C3 activation products deposited on a tumor cell by a specific mAb, and amplifies mAb-dependent complement activation and tumor cell lysis in vitro. In syngeneic models of metastatic lymphoma (EL4) and melanoma (B16), CR2Fc significantly enhanced the outcome of mAb therapy. Subsequent studies using the EL4 model with various genetically modified mice and macrophage-depleted mice revealed that CR2Fc enhanced the therapeutic effect of mAb therapy via both macrophage-dependent FcγR-mediated antibody-dependent cellular cytotoxicity, and by direct complement-mediated lysis. Complement activation products can also modulate adaptive immunity, but we found no evidence that either mAb or CR2Fc treatment had any effect on an antitumor humoral or cellular immune response. CR2Fc represents a potential adjuvant treatment to increase the effectiveness of mAb therapy of cancer. PMID:22442351

The XX sex chromosome complement in mice is associated with increased spontaneous lupus compared with XY.

Science.gov (United States)

Sasidhar, Manda V; Itoh, Noriko; Gold, Stefan M; Lawson, Gregory W; Voskuhl, Rhonda R

2012-08-01

Many autoimmune diseases are characterised by a female predominance. This may be caused by sex hormones, sex chromosomes or both. This report uses a transgenic mouse model to investigate how sex chromosome complement, not confounded by differences in gonadal type, might contribute to lupus pathogenesis. Transgenic NZM2328 mice were created by deletion of the Sry gene from the Y chromosome, thereby separating genetic from gonadal sex. Survival, renal histopathology and markers of immune activation were compared in mice carrying the XX versus the XY(-) sex chromosome complement, with each genotype being ovary bearing. Mice with XX sex chromosome complement compared with XY(-) exhibited poorer survival rates and increased kidney pathology. Splenic T lymphocytes from XX mice demonstrated upregulated X-linked CD40 ligand expression and higher levels of activation markers ex vivo. Increased MMP, TGF and IL-13 production was found, while IL-2 was lower in XX mice. An accumulation of splenic follicular B cells and peritoneal marginal zone B cells was observed, coupled with upregulated costimulatory marker expression on B cells in XX mice. These data show that the XX sex chromosome complement, compared with XY(-), is associated with accelerated spontaneous lupus.

Is Political Activism on Social Media an initiator of Psychological Stress?

Science.gov (United States)

Hisam, Aliya; Safoor, Iqra; Khurshid, Nawal; Aslam, Aakash; Zaid, Farhan; Muzaffar, Ayesha

2017-01-01

To find out the association of psychological stress with political activism on social networking sites (SNS) in adults. To find association of psychological stress and political activism with age, gender and occupational status. A descriptive cross-sectional study of 8 months (Aug 2014 to March 2015) was conducted on young adults between age group of 20-40 years of different universities of Rawalpindi, Pakistan. Closed ended standardized questionnaires (i.e. Cohen Perceived Stress-10) were distributed via non-probability convenient sampling among a total sample size of 237. Sample size was calculated using WHO sample size calculator and data was analyzed in STATA version 12. The mean age of participants was 21.06±1.425 years. Out of the 237 participants, 150 (63.3%) were males and 87 (36.7%) females. Regarding their occupation, 13 (51.9%) were military cadets, 8 (3.4%) were consultant, 47 (19.8%) medical officer, 3 (1.3%) PG students and 56 (23.6%) MBBS students. Significant association of occupation was established with both political activism and psychological stress (p=0.4 and p=0.002 respectively). Among 237 individuals, 91 (38.4%) were stressed out and 146 (61.6%) were not. Among whole sample, political activists on SNS were found to be 23 (9.7%). Out of these 23 individuals who were politically active, 15 (65.2%) were stressed out and 8 (34.7%) were not. A significant association between stress and political activism was established (p=0.005). Political activism via social networking sites is playing significant role on adult person's mental health in terms of stress among different occupation.

Complement inhibition accelerates regeneration in a model of peripheral nerve injury

NARCIS (Netherlands)

Ramaglia, Valeria; Tannemaat, Martijn Rudolf; de Kok, Maryla; Wolterman, Ruud; Vigar, Miriam Ann; King, Rosalind Helen Mary; Morgan, Bryan Paul; Baas, Frank

2009-01-01

Complement (C) activation is a crucial event in peripheral nerve degeneration but its effect on the subsequent regeneration is unknown. Here we show that genetic deficiency of the sixth C component, C6, accelerates axonal regeneration and recovery in a rat model of sciatic nerve injury. Foot-flick

Hole Drilling Technique – on site stress measurement

OpenAIRE

Schueremans, Luc

2009-01-01

2. Hole Drilling Technique for onsite stress measurement has been used to validate the stress level at 2 pillars of the Sint-Jacobschurch (Leuven, B). The technique allows estimating the stress in a stone from measuring deformation when a small hole is made. It is a low intrusive technique. The application of it is limited to local stress measurements and is a complement to stress estimate from calculations of from the use of –for example- flat jacks. In addition to the flat-jack technique...

Molecular Characterization of the Rhesus Rhadinovirus (RRV) ORF4 Gene and the RRV Complement Control Protein It Encodes▿

Science.gov (United States)

Mark, Linda; Spiller, O. Brad; Okroj, Marcin; Chanas, Simon; Aitken, Jim A.; Wong, Scott W.; Damania, Blossom; Blom, Anna M.; Blackbourn, David J.

2007-01-01

The diversity of viral strategies to modulate complement activation indicates that this component of the immune system has significant antiviral potential. One example is the Kaposi's sarcoma-associated herpesvirus (KSHV) complement control protein (KCP), which inhibits progression of the complement cascade. Rhesus rhadinovirus (RRV), like KSHV, is a member of the subfamily Gammaherpesvirinae and currently provides the only in vivo model of KSHV pathobiology in primates. In the present study, we characterized the KCP homologue encoded by RRV, RRV complement control protein (RCP). Two strains of RRV have been sequenced to date (H26-95 and 17577), and the RCPs they encode differ substantially in structure: RCP from strain H26-95 has four complement control protein (CCP) domains, whereas RCP from strain 17577 has eight CCP domains. Transcriptional analyses of the RCP gene (ORF4, referred to herein as RCP) in infected rhesus macaque fibroblasts mapped the ends of the transcripts of both strains. They revealed that H26-95 encodes a full-length, unspliced RCP transcript, while 17577 RCP generates a full-length unspliced mRNA and two alternatively spliced transcripts. Western blotting confirmed that infected cells express RCP, and immune electron microscopy disclosed this protein on the surface of RRV virions. Functional studies of RCP encoded by both RRV strains revealed their ability to suppress complement activation by the classical (antibody-mediated) pathway. These data provide the foundation for studies into the biological significance of gammaherpesvirus complement regulatory proteins in a tractable, non-human primate model. PMID:17287274

Assessment of brain activities during an emotional stress state using fMRI

International Nuclear Information System (INIS)

Hayashi, Takuto; Mizuno-Matsumoto, Yuko; Kawasaki, Aika; Kato, Makoto; Murata, Tsutomu

2011-01-01

We investigated cerebrum activation using functional magnetic resonance imaging during a mental stress state. Thirty-four healthy adults participated. Before the experiment, we assessed their stress states using the Stress Self-rating Scale and divided the participants into Stress and Non-stress groups. The experiment consisted of 6 trials. Each trial consisted of a 20-s block of emotional audio-visual stimuli (4-s stimulation x 5 slides) and a fixation point. These processes were performed 3 times continuously (Relaxed, Pleasant, Unpleasant stimuli) in a random order. These results showed that the Non-stress group indicated activation of the amygdala and hippocampus in the Pleasant and Unpleasant stimuli while the Stress group indicated activation of the hippocampus in Pleasant stimuli, and the amygdala and hippocampus in Unpleasant stimuli. These findings suggested that the mental stress state engages the reduction of emotional processing. Also, the responsiveness of the memory system remained during and after the emotional stress state. (author)

Emotional Intelligence, Physical Activity and Coping with Stress in Adolescents

Directory of Open Access Journals (Sweden)

Ali Aziz Dawood A L S U D A N I

2015-06-01

Full Text Available Participation in physical activity seems to be connected with better coping with stress and higher level emotional intelligence. The aim of the study is to check if there are any significant correlations between emotional intelligence, physical activity and style focused on the task in coping with stress. The sample was made by 90 adolesc ents, aged from 19 - 21 from Psychology department at University of Szczecin. To check the level of emotional inteligence was used polish version of Emotional Intelligence Questionaire. To check te level of physical activity was used s hort form of Internati onal Physical Activity Questionaire. To find out what kind of style is used by adolescents with coping with stress was used Polish version of Coping Inventory for Stressful Situations. There were signifficant correlations between physical activity an d task oriented coping, avoidance, social diversion, emotional intelligence (p<0.05. Regression analyses showed that task oriented coping and social diversion are predictors of physical activity. Results of one way Anova showed that the task - oriented copi ng, social diversion, walking, moderate and vigorous intensity physical activity, physical actrivity (in MET/min, emotional intelligence, identifying emotions and using emotions in practice of the high PA group were significantly higher (p<0.05 than in t he low PA group.

Job stressors and job stress among teachers engaged in nursing activity.

Science.gov (United States)

Muto, Shigeki; Muto, Takashi; Seo, Akihiko; Yoshida, Tsutomu; Taoda, Kazushi; Watanabe, Misuzu

2007-01-01

Teachers and staff members engaged in nursing activity experience more stress than other workers. However, it is unknown whether teachers engaged in nursing activity in schools for handicapped children experience even greater stress. This study evaluated job stressors and job stress among such teachers using a cross-sectional study design. The subjects were all 1,461 teachers from all 19 prefectural schools for handicapped children in Shizuoka Prefecture, Japan. We used a brief job stress questionnaire for the survey and 831 teachers completed the questionnaire. Job stressors among teachers engaged in nursing activity were compared with those among teachers not engaged in nursing activity. Job stress among such teachers was estimated by the score for total health risk, and was compared with the score in the Japanese general population. Male and female teachers engaged in nursing activity had a significantly higher level of job stressors for physical work load and job control compared with those not engaged in nursing activity. The scores for total health risk among male and female teachers engaged in nursing activity were 102 points and 98 points, respectively. These scores were not markedly above 100 points which is the mean score in the Japanese general population.

A new location to split Cre recombinase for protein fragment complementation.

Science.gov (United States)

Rajaee, Maryam; Ow, David W

2017-11-01

We have previously described a recombinase-mediated gene stacking system in which the Cre recombinase is used to remove lox-site flanked DNA no longer needed after each round of Bxb1 integrase-mediated site-specific integration. The Cre recombinase can be conveniently introduced by hybridization with a cre-expressing plant. However, maintaining an efficient cre-expressing line over many generations can be a problem, as high production of this DNA-binding protein might interfere with normal chromosome activities. To counter this selection against high Cre activity, we considered a split-cre approach, in which Cre activity is reconstituted after separate parts of Cre are brought into the same genome by hybridization. To insure that the recombinase-mediated gene stacking system retains its freedom to operate, we tested for new locations to split Cre into complementing fragments. In this study, we describe testing four new locations for splitting the Cre recombinase for protein fragment complementation and show that the two fragments of Cre split between Lys244 and Asn245 can reconstitute activity that is comparable to that of wild-type Cre. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Modulation of post-stroke degenerative and regenerative processes and subacute protection by site-targeted inhibition of the alternative pathway of complement.

Science.gov (United States)

Alawieh, Ali; Elvington, Andrew; Zhu, Hong; Yu, Jin; Kindy, Mark S; Atkinson, Carl; Tomlinson, Stephen

2015-12-30

Complement promotes neuroinflammation and injury in models of stroke. However, complement is also being increasingly implicated in repair and regeneration after central nervous system (CNS) injury, and some complement deficiencies have been shown to provide acute, but not subacute, protection after murine stroke. Here, we investigate the dual role of complement in injury and repair after cerebral ischemia and reperfusion. We used complement-deficient mice and different complement inhibitors in a model of transient middle cerebral artery occlusion to investigate complement-dependent cellular and molecular changes that occur through the subacute phase after stroke. C3 deficiency and site-targeted complement inhibition with either CR2-Crry (inhibits all pathways) or CR2-fH (inhibits alternative pathway) significantly reduced infarct size, reduced apoptotic cell death, and improved neurological deficit score in the acute phase after stroke. However, only in CR2-fH-treated mice was there sustained protection with no evolution of injury in the subacute phase. Whereas both inhibitors significantly reduced microglia/macrophage activation and astrogliosis in the subacute phase, only CR2-fH improved neurological deficit and locomotor function, maintained neurogenesis markers, enhanced neuronal migration, and increased VEGF expression. These findings in CR2-fH-treated mice correlated with improved performance in spatial learning and passive avoidance tasks. The complement anaphylatoxins have been implicated in repair and regenerative mechanisms after CNS injury, and in this context CR2-fH significantly reduced, but did not eliminate the generation of C5a within the brain, unlike CR2-Crry that completely blocked C5a generation. Gene expression profiling revealed that CR2-fH treatment downregulated genes associated with apoptosis, TGFβ signaling, and neutrophil activation, and decreased neutrophil infiltration was confirmed by immunohistochemistry. CR2-fH upregulated genes for

Prefrontal cortex activity is associated with biobehavioral components of the stress response

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Muriah D Wheelock

2016-11-01

Full Text Available Contemporary theory suggests that prefrontal cortex (PFC function is associated with individual variability in the psychobiology of the stress response. Advancing our understanding of this complex biobehavioral pathway has potential to provide insight into processes that determine individual differences in stress susceptibility. The present study used functional magnetic resonance imaging (fMRI to examine brain activity during a variation of the Montreal Imaging Stress Task (MIST in fifty-three young adults. Salivary cortisol was assessed as an index of the stress response, trait anxiety was assessed as an index of an individual’s disposition towards negative affectivity, and self-reported stress was assessed as an index of an individual’s subjective psychological experience. Heart rate and skin conductance responses were also assessed as additional measures of physiological reactivity. Dorsomedial PFC, dorsolateral PFC, and inferior parietal lobule demonstrated differential activity during the MIST. Further, differences in salivary cortisol reactivity to the MIST were associated with ventromedial PFC and posterior cingulate activity, while trait anxiety and self-reported stress were associated with dorsomedial and ventromedial PFC activity respectively. These findings underscore that PFC activity regulates behavioral and psychobiological components of the stress response.

Malaria parasite evasion of classical complement pathway attack

DEFF Research Database (Denmark)

Larsen, Mads Delbo; Ditlev, Sisse; Olmos, Rafael Bayarri

2017-01-01

of the protective antibodies that are gradually acquired in response to P. falciparum-IEs. Although this response is dominated by IgG1 and IgG3, complement-mediated attack following activation of the classical pathway does not appear to be a major effector mechanism. We hypothesized that this is related to the knob...... is that the knob-restricted expression of PfEMP1 on the IE surface may serve as a hitherto unappreciated immune evasion mechanism employed by P. falciparum parasites....

Identifying pathogenicity of human variants via paralog-based yeast complementation.

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Fan Yang

2017-05-01

Full Text Available To better understand the health implications of personal genomes, we now face a largely unmet challenge to identify functional variants within disease-associated genes. Functional variants can be identified by trans-species complementation, e.g., by failure to rescue a yeast strain bearing a mutation in an orthologous human gene. Although orthologous complementation assays are powerful predictors of pathogenic variation, they are available for only a few percent of human disease genes. Here we systematically examine the question of whether complementation assays based on paralogy relationships can expand the number of human disease genes with functional variant detection assays. We tested over 1,000 paralogous human-yeast gene pairs for complementation, yielding 34 complementation relationships, of which 33 (97% were novel. We found that paralog-based assays identified disease variants with success on par with that of orthology-based assays. Combining all homology-based assay results, we found that complementation can often identify pathogenic variants outside the homologous sequence region, presumably because of global effects on protein folding or stability. Within our search space, paralogy-based complementation more than doubled the number of human disease genes with a yeast-based complementation assay for disease variation.

Genotypic and phenotypic diversity of Lactobacillus rhamnosus clinical isolates, their comparison with strain GG and their recognition by complement system.

Science.gov (United States)

Nissilä, Eija; Douillard, François P; Ritari, Jarmo; Paulin, Lars; Järvinen, Hanna M; Rasinkangas, Pia; Haapasalo, Karita; Meri, Seppo; Jarva, Hanna; de Vos, Willem M

2017-01-01

Lactobacillus rhamnosus strains are ubiquitous in fermented foods, and in the human body where they are commensals naturally present in the normal microbiota composition of gut, vagina and skin. However, in some cases, Lactobacillus spp. have been implicated in bacteremia. The aim of the study was to examine the genomic and immunological properties of 16 clinical blood isolates of L. rhamnosus and to compare them to the well-studied L. rhamnosus probiotic strain GG. Blood cultures from bacteremic patients were collected at the Helsinki University Hospital laboratory in 2005-2011 and L. rhamnosus strains were isolated and characterized by genomic sequencing. The capacity of the L. rhamnosus strains to activate serum complement was studied using immunological assays for complement factor C3a and the terminal pathway complement complex (TCC). Binding of complement regulators factor H and C4bp was also determined using radioligand assays. Furthermore, the isolated strains were evaluated for their ability to aggregate platelets and to form biofilms in vitro. Genomic comparison between the clinical L. rhamnosus strains showed them to be clearly different from L. rhamnosus GG and to cluster in two distinct lineages. All L. rhamnosus strains activated complement in serum and none of them bound complement regulators. Four out of 16 clinical blood isolates induced platelet aggregation and/or formed more biofilms than L. rhamnosus GG, which did not display platelet aggregation activity nor showed strong biofilm formation. These findings suggest that clinical L. rhamnosus isolates show considerable heterogeneity but are clearly different from L. rhamnosus GG at the genomic level. All L. rhamnosus strains are still normally recognized by the human complement system.

Anisotropic swim stress in active matter with nematic order

Science.gov (United States)

Yan, Wen; Brady, John F.

2018-05-01

Active Brownian particles (ABPs) transmit a swim pressure {{{\\Pi }}}{{swim}}=n\\zeta {D}{{swim}} to the container boundaries, where ζ is the drag coefficient, D swim is the swim diffusivity and n is the uniform bulk number density far from the container walls. In this work we extend the notion of the isotropic swim pressure to the anisotropic tensorial swim stress {{\\boldsymbol{σ }}}{{swim}}=-n\\zeta {{\\boldsymbol{D}}}{{swim}}, which is related to the anisotropic swim diffusivity {{\\boldsymbol{D}}}{{swim}}. We demonstrate this relationship with ABPs that achieve nematic orientational order via a bulk external field. The anisotropic swim stress is obtained analytically for dilute ABPs in both 2D and 3D systems. The anisotropy, defined as the ratio of the maximum to the minimum of the three principal stresses, is shown to grow exponentially with the strength of the external field. We verify that the normal component of the anisotropic swim stress applies a pressure {{{\\Pi }}}{{swim}}=-({{\\boldsymbol{σ }}}{{swim}}\\cdot {\\boldsymbol{n}})\\cdot {\\boldsymbol{n}} on a wall with normal vector {\\boldsymbol{n}}, and, through Brownian dynamics simulations, this pressure is shown to be the force per unit area transmitted by the active particles. Since ABPs have no friction with a wall, the difference between the normal and tangential stress components—the normal stress difference—generates a net flow of ABPs along the wall, which is a generic property of active matter systems.

Constitutive role of the Fanconi anemia D2 gene in the replication stress response.

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Tian, Yanyan; Shen, Xi; Wang, Rui; Klages-Mundt, Naeh L; Lynn, Erica J; Martin, Sara K; Ye, Yin; Gao, Min; Chen, Junjie; Schlacher, Katharina; Li, Lei

2017-12-08

In response to DNA cross-linking damage, the Fanconi anemia (FA) core complex activates the FA pathway by monoubiquitinating Fanconi anemia complementation group D2 (FANCD2) for the initiation of the nucleolytic processing of the DNA cross-links and stabilization of stalled replication forks. Given that all the classic FA proteins coordinately monoubiquitinate FANCD2, it is unclear why losses of individual classic FA genes yield varying cellular sensitivities to cross-linking damage. To address this question, we generated cellular knock-out models of FA core complex components and FANCD2 and found that FANCD2-null mutants display higher levels of spontaneous chromosomal damage and hypersensitivity to replication-blocking lesions than Fanconi anemia complementation group L (FANCL)-null mutants, suggesting that FANCD2 provides a basal level of DNA protection countering endogenous lesions in the absence of monoubiquitination. FANCD2's ubiquitination-independent function is likely involved in optimized recruitment of nucleolytic activities for the processing and protection of stressed replication forks. Our results reveal that FANCD2 has a ubiquitination-independent role in countering endogenous levels of replication stress, a function that is critical for the maintenance of genomic stability. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Coordinated Expression of Borrelia burgdorferi Complement Regulator-Acquiring Surface Proteins during the Lyme Disease Spirochete's Mammal-Tick Infection Cycle▿

OpenAIRE

Bykowski, Tomasz; Woodman, Michael E.; Cooley, Anne E.; Brissette, Catherine A.; Brade, Volker; Wallich, Reinhard; Kraiczy, Peter; Stevenson, Brian

2007-01-01

The Lyme disease spirochete, Borrelia burgdorferi, is largely resistant to being killed by its hosts’ alternative complement activation pathway. One possible resistance mechanism of these bacteria is to coat their surfaces with host complement regulators, such as factor H. Five different B. burgdorferi outer surface proteins having affinities for factor H have been identified: complement regulator-acquiring surface protein 1 (BbCRASP-1), encoded by cspA; BbCRASP-2, encoded by cspZ; and three ...

Cocaine induces astrocytosis through ER stress-mediated activation of autophagy

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Periyasamy, Palsamy; Guo, Ming-Lei; Buch, Shilpa

2016-01-01

ABSTRACT Cocaine is known to induce inflammation, thereby contributing in part, to the pathogenesis of neurodegeneration. A recent study from our lab has revealed a link between macroautophagy/autophagy and microglial activation. The current study was aimed at investigating whether cocaine could also mediate activation of astrocytes and, whether this process involved induction of autophagy. Our findings demonstrated that cocaine mediated the activation of astrocytes by altering the levels of autophagy markers, such as BECN1, ATG5, MAP1LC3B-II, and SQSTM1 in both human A172 astrocytoma cells and primary human astrocytes. Furthermore, cocaine treatment resulted in increased formation of endogenous MAP1LC3B puncta in human astrocytes. Additionally, astrocytes transfected with the GFP-MAP1LC3B plasmid also demonstrated cocaine-mediated upregulation of the green fluorescent MAP1LC3B puncta. Cocaine-mediated induction of autophagy involved upstream activation of ER stress proteins such as EIF2AK3, ERN1, ATF6 since blockage of autophagy using either pharmacological or gene-silencing approaches, had no effect on cocaine-mediated induction of ER stress. Using both pharmacological and gene-silencing approaches to block either ER stress or autophagy, our findings demonstrated that cocaine-induced activation of astrocytes (measured by increased levels of GFAP) involved sequential activation of ER stress and autophagy. Cocaine-mediated-increased upregulation of GFAP correlated with increased expression of proinflammatory mediators such as TNF, IL1B, and IL6. In conclusion, these findings reveal an association between ER stress-mediated autophagy and astrogliosis in cocaine-treated astrocytes. Intervention of ER stress and/or autophagy signaling would thus be promising therapeutic targets for abrogating cocaine-mediated neuroinflammation. PMID:27337297

The role of complement in the acquired immune response

DEFF Research Database (Denmark)

Nielsen, C H; Fischer, E M; Leslie, R G

2000-01-01

Studies over the past three decades have clearly established a central role for complement in the promotion of a humoral immune response. The primary function of complement, in this regard, is to opsonize antigen or immune complexes for uptake by complement receptor type 2 (CR2, CD21) expressed...... on B cells, follicular dendritic cells (FDC) and some T cells. A variety of mechanisms appear to be involved in complement-mediated promotion of the humoral response. These include: enhancement of antigen (Ag) uptake and processing by both Ag-specific and non-specific B cells for presentation...

Vigorous physical activity, mental health, perceived stress, and socializing among college students.

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Vankim, Nicole A; Nelson, Toben F

2013-01-01

To examine cross-sectional associations between vigorous physical activity, mental health, perceived stress, and socializing among 4-year college students. A national cross-sectional sample of 4-year colleges in the United States. Ninety-four 4-year colleges in the United States. A total of 14,804 undergraduate students. Self-report vigorous physical activity, perceived stress (measured using the Cohen Perceived Stress Scale), mental health (measured using the SF-36), and socializing (assessed using self-report number of friends and hours spent socializing). Logistic regression models accounting for clustering within schools were estimated to examine the association between vigorous physical activity, mental health, perceived stress, and socializing. Adjusted models included high school vigorous physical activity and sociodemographic characteristics. Students who met vigorous physical activity recommendations were less likely to report poor mental health (adjusted odds ratio [OR]: .79; 95% confidence interval [CI]: .69, .90) and perceived stress (adjusted OR: .75; 95% CI: .67, .83) than students who did not meet recommendations. In addition, socializing partially mediated the relationship between vigorous physical activity, mental health, and perceived stress; however, race and sex did not moderate the relationship. Interventions aiming to improve mental well-being of college students should also consider promoting physical activity. At least some of the positive benefits of physical activity may arise from social interactions.

Vigorous Physical Activity, Mental Health, Perceived Stress, and Socializing Among College Students

Science.gov (United States)

VanKim, Nicole A.; Nelson, Toben F.

2013-01-01

Purpose To examine cross-sectional associations between vigorous physical activity, mental health, perceived stress, and socializing among 4-year college students. Design A national cross-sectional sample of 4-year colleges in the United States. Setting Ninety-four 4-year colleges in the United States. Subjects A total of 14,804 undergraduate students. Measures Self-report vigorous physical activity, perceived stress (measured using the Cohen Perceived Stress Scale), mental health (measured using the SF-36), and socializing (assessed using self-report number of friends and hours spent socializing). Analysis Logistic regression models accounting for clustering within schools were estimated to examine the association between vigorous physical activity, mental health, perceived stress, and socializing. Adjusted models included high school vigorous physical activity and sociodemographic characteristics. Results Students who met vigorous physical activity recommendations were less likely to report poor mental health (adjusted odds ratio [OR]: .79; 95% confidence interval [CI]: .69, .90) and perceived stress (adjusted OR: .75; 95% CI: .67, .83) than students who did not meet recommendations. In addition, socializing partially mediated the relationship between vigorous physical activity, mental health, and perceived stress; however, race and sex did not moderate the relationship. Conclusion Interventions aiming to improve mental well-being of college students should also consider promoting physical activity. At least some of the positive benefits of physical activity may arise from social interactions. PMID:23470187

Monitoring eruption activity using temporal stress changes at Mount Ontake volcano.

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Terakawa, Toshiko; Kato, Aitaro; Yamanaka, Yoshiko; Maeda, Yuta; Horikawa, Shinichiro; Matsuhiro, Kenjiro; Okuda, Takashi

2016-02-19

Volcanic activity is often accompanied by many small earthquakes. Earthquake focal mechanisms represent the fault orientation and slip direction, which are influenced by the stress field. Focal mechanisms of volcano-tectonic earthquakes provide information on the state of volcanoes via stresses. Here we demonstrate that quantitative evaluation of temporal stress changes beneath Mt. Ontake, Japan, using the misfit angles of focal mechanism solutions to the regional stress field, is effective for eruption monitoring. The moving average of misfit angles indicates that during the precursory period the local stress field beneath Mt. Ontake was deviated from the regional stress field, presumably by stress perturbations caused by the inflation of magmatic/hydrothermal fluids, which was removed immediately after the expulsion of volcanic ejecta. The deviation of the local stress field can be an indicator of increases in volcanic activity. The proposed method may contribute to the mitigation of volcanic hazards.

Characterization and expression analysis of a complement component gene in sea cucumber ( Apostichopus japonicus)

Science.gov (United States)

Chen, Zhong; Zhou, Zunchun; Yang, Aifu; Dong, Ying; Guan, Xiaoyan; Jiang, Bei; Wang, Bai

2015-12-01

The complement system plays a crucial role in the innate immune system of animals. It can be activated by distinct yet overlapping classical, alternative and lectin pathways. In the alternative pathway, complement factor B (Bf) serves as the catalytic subunit of complement component 3 (C3) convertase, which plays the central role among three activation pathways. In this study, the Bf gene in sea cucumber ( Apostichopus japonicus), termed AjBf, was obtained by rapid amplification of cDNA ends (RACE). The full-length cDNA of AjBf was 3231 bp in length barring the poly (A) tail. It contained an open reading frame (ORF) of 2742 bp encoding 913 amino acids, a 105 bp 5'-UTR (5'-terminal untranslated region) and a 384 bp 3'-UTR. AjBf was a mosaic protein with six CCP (complement control protein) domains, a VWA (von Willebrand factor A) domain, and a serine protease domain. The deduced molecular weight of AjBf protein was 101 kDa. Quantitative real time PCR (qRT-PCR) analysis indicated that the expression level of AjBf in A. japonicus was obviously higher at larval stage than that at embryonic stage. Expression detection in different tissues showed that AjBf expressed higher in coelomocytes than in other four tissues. In addation, AjBf expression in different tissues was induced significantly after LPS or PolyI:C challenge. These results indicated that AjBf plays an important role in immune responses to pathogen infection.

Induced resistance in tomato by SAR activators during predisposing salinity stress

Directory of Open Access Journals (Sweden)

Matthew Francis Pye

2013-05-01

Full Text Available Plant activators are chemicals that induce disease resistance. The phytohormone salicylic acid (SA is a crucial signal for systemic acquired resistance (SAR, and SA-mediated resistance is a target of several commercial plant activators, including Actigard (1,2,3-benzothiadiazole-7-thiocarboxylic acid-s-methyl-ester, BTH and Tiadinil (N-(3-chloro-4-methylphenyl-4-methyl-1,2,3-thiadiazole-5-carboxamide, TDL. BTH and TDL were examined for their impact on abscisic acid (ABA-mediated, salt-induced disease predisposition in tomato seedlings. A brief episode of salt stress to roots significantly increased the severity of disease caused by Pseudomonas syringae pv. tomato (Pst and Phytophthora capsici relative to non-stressed plants. Root treatment with TDL induced resistance to Pst in leaves and provided protection in both non-stressed and salt-stressed seedlings in WT and highly susceptible NahG plants. Non-stressed and salt-stressed ABA-deficient sitiens mutants were highly resistant to Pst. Neither TDL nor BTH induced resistance to root infection by P. capsici, nor did they moderate the salt-induced increment in disease severity. Root treatment with these plant activators increased the levels of ABA in roots and shoots similar to levels observed in salt-stressed plants. The results indicate that SAR activators can protect tomato plants from bacterial speck disease under predisposing salt stress, and suggest that some SA-mediated defense responses function sufficiently in plants with elevated levels of ABA.

HIV protease inhibitors disrupt lipid metabolism by activating endoplasmic reticulum stress and inhibiting autophagy activity in adipocytes.

Directory of Open Access Journals (Sweden)

Beth S Zha

Full Text Available HIV protease inhibitors (PI are core components of Highly Active Antiretroviral Therapy (HAART, the most effective treatment for HIV infection currently available. However, HIV PIs have now been linked to lipodystrophy and dyslipidemia, which are major risk factors for cardiovascular disease and metabolic syndrome. Our previous studies have shown that HIV PIs activate endoplasmic reticulum (ER stress and disrupt lipid metabolism in hepatocytes and macrophages. Yet, little is known on how HIV PIs disrupt lipid metabolism in adipocytes, a major cell type involved in the pathogenesis of metabolic syndrome.Cultured and primary mouse adipocytes and human adipocytes were used to examine the effect of frequently used HIV PIs in the clinic, lopinavir/ritonavir, on adipocyte differentiation and further identify the underlying molecular mechanism of HIV PI-induced dysregulation of lipid metabolism in adipocytes. The results indicated that lopinavir alone or in combination with ritonavir, significantly activated the ER stress response, inhibited cell differentiation, and induced cell apoptosis in adipocytes. In addition, HIV PI-induced ER stress was closely linked to inhibition of autophagy activity. We also identified through the use of primary adipocytes of CHOP(-/- mice that CHOP, the major transcriptional factor of the ER stress signaling pathway, is involved in lopinavir/ritonavir-induced inhibition of cell differentiation in adipocytes. In addition, lopinavir/ritonavir-induced ER stress appears to be associated with inhibition of autophagy activity in adipocytes.Activation of ER stress and impairment of autophagy activity are involved in HIV PI-induced dysregulation of lipid metabolism in adipocytes. The key components of ER stress and autophagy signaling pathways are potential therapeutic targets for HIV PI-induced metabolic side effects in HIV patients.

Complement 5a stimulates macrophage polarization and contributes to tumor metastases of colon cancer.

Science.gov (United States)

Piao, Chunmei; Zhang, Wen-Mei; Li, Tao-Tao; Zhang, Cong-Cong; Qiu, Shulan; Liu, Yan; Liu, Sa; Jin, Ming; Jia, Li-Xin; Song, Wen-Chao; Du, Jie

2018-05-15

Inflammatory cells such as macrophages can play a pro-tumorigenic role in the tumor stroma. Tumor-associated macrophages (TAMs) generally display an M2 phenotype with tumor-promoting activity; however, the mechanisms regulating the TAM phenotype remain unclear. Complement 5a (C5a) is a cytokine-like polypeptide that is generated during complement system activation and is known to promote tumor growth. Herein, we investigated the role of C5a on macrophage polarization in colon cancer metastasis in mice. We found that deficiency of the C5a receptor (C5aR) severely impairs the metastatic ability of implanted colon cancer cells. C5aR was expressed on TAMs, which exhibited an M2-like functional profile in colon cancer liver metastatic lesions. Furthermore, C5a mediated macrophage polarization and this process relied substantially on activation of the nuclear factor-kappa B (NF-κB) pathway. Finally, analysis of human colon carcinoma indicated that C5aR expression is negatively associated with tumor differentiation grade. Our results demonstrate that C5aR has a central role in regulating the M2 phenotype of TAMs, which in turn, contributes to hepatic metastasis of colon cancer through NF-κB signaling. C5a is a potential novel marker for cancer prognosis and drugs targeting complement system activation, specifically the C5aR pathway, may offer new therapeutic opportunities for colon cancer management. Copyright © 2018 Elsevier Inc. All rights reserved.