Sample records for anaphylatoxins

  1. Anaphylatoxin C3a receptors in asthma


    Panettieri Reynold A; Ali Hydar


    Abstract The complement system forms the central core of innate immunity but also mediates a variety of inflammatory responses. Anaphylatoxin C3a, which is generated as a byproduct of complement activation, has long been known to activate mast cells, basophils and eosinophils and to cause smooth muscle contraction. However, the role of C3a in the pathogenesis of allergic asthma remains unclear. In this review, we examine the role of C3a in promoting asthma. Following allergen challenge, C3a i...

  2. DMPD: Functions of anaphylatoxin C5a in rat liver: direct and indirect actions onnonparenchymal and parenchymal cells. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 11367531 Functions of anaphylatoxin C5a in rat liver: direct and indirect actions o...ol. 2001 Mar;1(3):469-81. (.png) (.svg) (.html) (.csml) Show Functions of anaphylatoxin C5a in rat liver: di...31 Title Functions of anaphylatoxin C5a in rat liver: direct and indirect actions onnonparenchymal and paren

  3. Micrurus snake venoms activate human complement system and generate anaphylatoxins

    Directory of Open Access Journals (Sweden)

    Tanaka Gabriela D


    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.

  4. Anaphylatoxins coordinate innate and adaptive immune responses in allergic asthma. (United States)

    Schmudde, Inken; Laumonnier, Yves; Köhl, Jörg


    Allergic asthma is a chronic disease of the airways in which maladaptive Th2 and Th17 immune responses drive airway hyperresponsiveness (AHR), eosinophilic and neutrophilic airway inflammation and mucus overproduction. Airway epithelial and pulmonary vascular endothelial cells in concert with different resident and monocyte-derived dendritic cells (DC) play critical roles in allergen sensing and consecutive activation of TH cells and their differentiation toward TH2 and TH17 effector or regulatory T cells (Treg). Further, myeloid-derived regulatory cells (MDRC) act on TH cells and either suppress or enhance their activation. The complement-derived anaphylatoxins (AT) C3a and C5a are generated during initial antigen encounter and regulate the development of maladaptive immunity at allergen sensitization. Here, we will review the complex role of ATs in activation and modulation of different DC populations, MDRCs and CD4⁺ TH cells. We will also discuss the potential impact of ATs on the regulation of the pulmonary stromal compartment as an important means to regulate DC functions. PMID:23694705

  5. Degradation of C3a anaphylatoxins by rat mast cells

    International Nuclear Information System (INIS)

    Incubation of 125I-human C3a with rat peritoneal mast cells (RMC) causes extensive degradation of the ligand. Both cell-bound and free 125I-C3a (hu) was degraded by RMC, even at 00C, based on SDS-PAGE analysis. The authors examined several protease inhibitors for their ability to prevent degradation of 125I-C3a (hu). Degradation of 125I-C3a (hu) by RMC was not inhibited by leupeptin, antipain, elastatinal, pepstatin, α1-antitrypsin or EDTA. TPCK and TLCK were only partially effective. PMSF, chymostatin and SBTI were most effective in preventing 125I-C3a (hu) degradation. These latter compounds are effective inhibitors of the chymotrypsin-like enzyme chymase extracted from RMC, as is TPCK, based on hydrolysis of the substrate BTEE. Degradation of cell-bound ligand is totally prevented only by PMSF (or DFP). Therefore, 125I-C3a (hu) bound to the RMC appears to be degraded predominantly by chymase; however the cell-bound ligand is attacked by other surface proteases. Degradation of rat C3a by RMC was examined. After incubation with RMC, cell-bound and free 125I-C3a (rat) showed no evidence of degradation with or without inhibitors present. From these results, the authors conclude that chymase may not play a significant role in regulating anaphylatoxin activity. Furthermore, the authors propose that rat C3a is a preferred ligand for identifying receptors on mast cells because of its resistance to proteolysis

  6. The anaphylatoxin C3a downregulates the Th2 response to epicutaneously introduced antigen


    Kawamoto, Seiji; Yalcindag, Ali; Laouini, Dhafer; Brodeur, Scott; Bryce, Paul; Lu, Bao; Humbles, Alison A.; Oettgen, Hans; Gerard, Craig; Geha, Raif S.


    Mechanical injury to the skin results in activation of the complement component C3 and release of the anaphylatoxin C3a. C3a binds to a seven-transmembrane G protein–coupled receptor, C3aR. We used C3aR–/– mice to examine the role of C3a in a mouse model of allergic inflammation induced by epicutaneous sensitization with OVA. C3aR–/– mice exhibited an exaggerated Th2 response to epicutaneous but not to intraperitoneal sensitization with OVA, as evidenced by significantly elevated levels of se...

  7. Structural and functional characterization of human and murine C5a anaphylatoxins

    Energy Technology Data Exchange (ETDEWEB)

    Schatz-Jakobsen, Janus Asbjørn; Yatime, Laure, E-mail:; Larsen, Casper [Aarhus University, Gustav Wieds Vej 10C, DK-8000 Aarhus (Denmark); Petersen, Steen Vang [Aarhus University, Bartholin Building, Wilhelm Meyers Allé 4, DK-8000 Aarhus (Denmark); Klos, Andreas [Medical School Hannover, Hannover (Germany); Andersen, Gregers Rom, E-mail: [Aarhus University, Gustav Wieds Vej 10C, DK-8000 Aarhus (Denmark)


    The structure of the human C5aR antagonist, C5a-A8, reveals a three-helix bundle conformation similar to that observed for human C5a-desArg, whereas murine C5a and C5a-desArg both form the canonical four-helix bundle. These conformational differences are discussed in light of the differential C5aR activation properties observed for the human and murine complement anaphylatoxins across species. Complement is an ancient part of the innate immune system that plays a pivotal role in protection against invading pathogens and helps to clear apoptotic and necrotic cells. Upon complement activation, a cascade of proteolytic events generates the complement effectors, including the anaphylatoxins C3a and C5a. Signalling through their cognate G-protein coupled receptors, C3aR and C5aR, leads to a wide range of biological events promoting inflammation at the site of complement activation. The function of anaphylatoxins is regulated by circulating carboxypeptidases that remove their C-terminal arginine residue, yielding C3a-desArg and C5a-desArg. Whereas human C3a and C3a-desArg adopt a canonical four-helix bundle fold, the conformation of human C5a-desArg has recently been described as a three-helix bundle. Here, the crystal structures of an antagonist version of human C5a, A8{sup Δ71–73}, and of murine C5a and C5a-desArg are reported. Whereas A8{sup Δ71–73} adopts a three-helix bundle conformation similar to human C5a-desArg, the two murine proteins form a four-helix bundle. A cell-based functional assay reveals that murine C5a-desArg, in contrast to its human counterpart, exerts the same level of activition as murine C5a on its cognate receptor. The role of the different C5a conformations is discussed in relation to the differential activation of C5a receptors across species.

  8. 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;


    anaphylatoxin production through complement activation. Despite the general view that vesicle surface camouflaging with mPEG should dramatically suppress complement activation, here we show that bilayer enrichment of noncomplement activating liposomes [di-palmitoylphosphatidylcholine (DPPC) vesicles] with...

  9. Negative Regulation of Pulmonary Th17 Responses by C3a Anaphylatoxin during Allergic Inflammation in Mice


    Hoyong Lim; Young Uk Kim; Drouin, Scott M.; Stacey Mueller-Ortiz; Kyoungah Yun; Eva Morschl; Wetsel, Rick A.; Yeonseok Chung


    Activation of complement is one of the earliest immune responses to exogenous threats, resulting in various cleavage products including anaphylatoxin C3a. In addition to its contribution to host defense, C3a has been shown to mediate Th2 responses in animal models of asthma. However, the role of C3a on pulmonary Th17 responses during allergic inflammation remains unclear. Here, we show that mice deficient in C3a receptor (C3aR) exhibited (i) higher percentages of endogenous IL-17-producing CD...

  10. C5a of Cynoglossus semilaevis has anaphylatoxin-like properties and promotes antibacterial and antiviral defense. (United States)

    Li, Mo-Fei; Hu, Yong-Hua


    Activation of the complement system leads to the cleavage of component factor C5 into C5a and C5b. C5a can induce chemotaxis and inflammatory responses in mammals. The function of C5a in fish is poorly understood. In this study, we report the identification and analysis of a C5 homologue, CsC5, from tongue sole (Cynoglossus semilaevis). CsC5 is composed of 1683 amino acid residues that include an anaphylatoxin homologous domain. Expression of CsC5 could be detected in a variety of tissues and was up-regulated by bacterial or viral pathogen infection. Purified recombinant CsC5a (rCsC5a) could bind to peripheral blood leukocytes (PBL) and stimulate PBL chemotaxis, proliferation, respiratory burst, acid phosphatase activity, and phagocytosis. Tongue sole administered rCsC5a exhibited enhanced resistance against bacterial and viral infections. These results indicate that CsC5a is an anaphylatoxin with a role in innate immune defense against bacterial and viral infections. PMID:26934108

  11. 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; Jørgensen, Kent; Szebeni, J.


    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...... anaphylatoxin production through complement activation. Despite the general view that vesicle surface camouflaging with mPEG should dramatically suppress complement activation, here we show that bilayer enrichment of noncomplement activating liposomes [di-palmitoylphosphatidylcholine (DPPC) vesicles] with...... in activation of both classical and alternative pathways of complement and anaphylatoxin production (reflected in significant rises in SC5b-9, C4d, and C3a-desarg levels in normal human sera as well as SC5b-9 in EGTA-chelated/Mg2+ supplemented serum), since methylation of the phosphate oxygen of...

  12. Negative regulation of pulmonary Th17 responses by C3a anaphylatoxin during allergic inflammation in mice.

    Directory of Open Access Journals (Sweden)

    Hoyong Lim

    Full Text Available Activation of complement is one of the earliest immune responses to exogenous threats, resulting in various cleavage products including anaphylatoxin C3a. In addition to its contribution to host defense, C3a has been shown to mediate Th2 responses in animal models of asthma. However, the role of C3a on pulmonary Th17 responses during allergic inflammation remains unclear. Here, we show that mice deficient in C3a receptor (C3aR exhibited (i higher percentages of endogenous IL-17-producing CD4(+ T cells in the lungs, (ii higher amounts of IL-17 in the bronchoalveolar lavage fluid, and (iii more neutrophils in the lungs than wild-type mice when challenged with intranasal allergens. Moreover, adoptive transfer experiments showed that the frequencies of antigen-specific IL-17-producing CD4(+ T cells were significantly higher in the lungs and bronchial lymph nodes of C3aR-deficient recipients than those of wild-types recipients. Bone-marrow reconstitution study indicated that C3aR-deficiency on hematopoietic cells was required for the increased Th17 responses. Furthermore, C3aR-deficient mice exhibited increased percentages of Foxp3(+ regulatory T cells; however, depletion of these cells minimally affected the induction of antigen-specific Th17 cell population in the lungs. Neutralization of IL-17 significantly reduced the number of neutrophils in bronchoalveolar lavage fluid of C3aR-deficient mice. Our findings demonstrate that C3a signals negatively regulate antigen-specific Th17 responses during allergic lung inflammation and the size of Foxp3(+ regulatory T cell population in the periphery.

  13. Control of the collective migration of enteric neural crest cells by the Complement anaphylatoxin C3a and N-cadherin. (United States)

    Broders-Bondon, Florence; Paul-Gilloteaux, Perrine; Gazquez, Elodie; Heysch, Julie; Piel, Matthieu; Mayor, Roberto; Lambris, John D; Dufour, Sylvie


    We analyzed the cellular and molecular mechanisms governing the adhesive and migratory behavior of enteric neural crest cells (ENCCs) during their collective migration within the developing mouse gut. We aimed to decipher the role of the complement anaphylatoxin C3a during this process, because this well-known immune system attractant has been implicated in cephalic NCC co-attraction, a process controlling directional migration. We used the conditional Ht-PA-cre transgenic mouse model allowing a specific ablation of the N-cadherin gene and the expression of a fluorescent reporter in migratory ENCCs without affecting the central nervous system. We performed time-lapse videomicroscopy of ENCCs from control and N-cadherin mutant gut explants cultured on fibronectin (FN) and micropatterned FN-stripes with C3a or C3aR antagonist, and studied cell migration behavior with the use of triangulation analysis to quantify cell dispersion. We performed ex vivo gut cultures with or without C3aR antagonist to determine the effect on ENCC behavior. Confocal microscopy was used to analyze the cell-matrix adhesion properties. We provide the first demonstration of the localization of the complement anaphylatoxin C3a and its receptor on ENCCs during their migration in the embryonic gut. C3aR receptor inhibition alters ENCC adhesion and migration, perturbing directionality and increasing cell dispersion both in vitro and ex vivo. N-cadherin-null ENCCs do not respond to C3a co-attraction. These findings indicate that C3a regulates cell migration in a N-cadherin-dependent process. Our results shed light on the role of C3a in regulating collective and directional cell migration, and in ganglia network organization during enteric nervous system ontogenesis. The detection of an immune system chemokine in ENCCs during ENS development may also shed light on new mechanisms for gastrointestinal disorders. PMID:27041467

  14. Stimulation of glycogen phosphorylase in rat hepatocytes via prostanoid release from Kupffer cells by recombinant rat anaphylatoxin C5a but not by native human C5a in hepatocyte/Kupffer cell co-cultures


    Hespeling, Ursula; Püschel, Gerhard; Jungermann, Kurt; Götze, Otto; Zwirner, Jörg


    Human anaphylatoxin C3a had previously been shown to increase glycogenolysis in perfused rat liver and prostanoid formation in rat liver macrophages. Surprisingly, human C5a, which in other systems elicited stronger responses than C3a, did not increase glycogenolysis in perfused rat liver. Species incompatibilities within the experimental system had been supposed to be the reason. The current study supports this hypothesis: (1) In rat liver macrophages that had been maintained in primary cult...

  15. Sulfated Tyrosines Contribute to the Formation of the C5a Docking Site of the Human C5a Anaphylatoxin Receptor (United States)

    Farzan, Michael; Schnitzler, Christine E.; Vasilieva, Natalya; Leung, Doris; Kuhn, Jens; Gerard, Craig; Gerard, Norma P.; Choe, Hyeryun


    The complement anaphylatoxin C5a and its seven-transmembrane segment (7TMS) receptor play an important role in host defense and in a number of inflammation-associated pathologies. The NH2-terminal domain of the C5a receptor (C5aR/CD88) contributes substantially to its ability to bind C5a. Here we show that the tyrosines at positions 11 and 14 of the C5aR are posttranslationally modified by the addition of sulfate groups. The sulfate moieties of each of these tyrosines are critical to the ability of the C5aR to bind C5a and to mobilize calcium. A C5aR variant lacking these sulfate moieties efficiently mobilized calcium in response to a small peptide agonist, but not to C5a, consistent with a two-site model of ligand association in which the tyrosine-sulfated region of the C5aR mediates the initial docking interaction. A peptide based on the NH2 terminus of the C5aR and sulfated at these two tyrosines, but not its unsulfated analogue or a doubly sulfated control peptide, partially inhibited C5a association with its receptor. These observations clarify structural and mutagenic studies of the C5a/C5aR association and suggest that related 7TMS receptors are also modified by functionally important sulfate groups on their NH2-terminal tyrosines. PMID:11342590

  16. Role of C3, C5 and Anaphylatoxin Receptors in Acute Lung Injury and in Sepsis


    Bosmann, Markus; Ward, Peter A.


    The complement system plays a major role in innate immune defenses against infectious agents, but exaggerated activation of complement can lead to severe tissue injury. Systemic (intravascular) activation of complement can, via C5a, lead to neutrophil (PMN) activation, sequestration and adhesion to the pulmonary capillary endothelium, resulting in damage and necrosis of vascular endothelial cells and acute lung injury (ALI). Intrapulmonary (intraalveolar) activation of complement can cause AL...

  17. Degradation of human anaphylatoxin C3a by rat peritoneal mast cells: a role for the secretory granule enzyme chymase and heparin proteoglycan

    International Nuclear Information System (INIS)

    Purified human C3a was iodinated (125I-C3a) and used to study the interaction of labeled peptide with rat peritoneal mast cells (RMC). Cellular binding of 125I-C3a occurred within 30 sec, followed by a rapid dissociation from the cell. Both the binding of 125I-C3a and the rate of dissociation from the cell were temperature dependent. At 00C, the binding of 125I-C3a was increased and the rate of dissociation reduced, as compared to 370C. Once 125I-C3a was exposed to RMC, it lost the ability to rebind to a second batch of RMC. Analysis of the supernatants by trichloroacetic acid (TCA) precipitation and electrophoresis in sodium dodecyl sulfate polyacrylamide gels (SDS PAGE) revealed a decrease in the fraction of 125I precipitable by TCA and the appearance of 125I-C3a cleavage fragments. Pretreatment of RMC with enzyme inhibitors specific for chymotrypsin, but not trypsin, abrogated the degradation of 125I-C3a. Treatment of RMC bearing 125I-C3a with Bis (sulfosuccinimidyl) suberate (BS3) covalently crosslinked the 125I-Ca to chymase, the predominant enzyme found in the secretory granules. Indirect immunofluorescence of RMC using the IgG fraction of goat anti-rat chymase showed that chymase is present on the surface of unstimulated cells. The results indicate that 125I-C3a binds to RMC and is promptly degraded by chymase in the presence of heparin proteoglycan. In addition, this proteolysis of 125I-C3a by chymase must be blocked in order to detect plasma membrane C3a binding components on RMC

  18. Anaphylatoxin-mediated regulation of the immune response. I. C3a- mediated suppression of human and murine humoral immune responses



    The C3a fragment of the third component of complement was found to have immunosuppressive properties. C3a is capable of suppressing both specific and polyclonal antibody responses. In contrast, C3a had no effect on antigen- or mitogen-induced B or T cell proliferative responses. The carboxy-terminal arginine is essential for C3a to exhibit its immunosuppressive properties. The serum carboxypeptidase inhibitor 2-mercaptomethyl-5-guanodinopentanoic acid, which prevents cleavage of the terminal ...

  19. Connecting the innate and adaptive immune responses in mouse choroidal neovascularization via the anaphylatoxin C5a and γδT-cells (United States)

    Coughlin, Beth; Schnabolk, Gloriane; Joseph, Kusumam; Raikwar, Himanshu; Kunchithapautham, Kannan; Johnson, Krista; Moore, Kristi; Wang, Yi; Rohrer, Bärbel


    Neovascular age-related macular degeneration (AMD) is characterized by choroidal neovascularization (CNV). An overactive complement system is associated with AMD pathogenesis, and serum pro-inflammatory cytokines, including IL-17, are elevated in AMD patients. IL-17 is produced by complement C5a-receptor-expressing T-cells. In murine CNV, infiltrating γδT- rather than Th17-cells produce the IL-17 measurable in lesioned eyes. Here we asked whether C5a generated locally in response to CNV recruits IL-17-producing T-cells to the eye. CNV lesions were generated using laser photocoagulation and quantified by imaging; T-lymphocytes were characterized by QRT-PCR. CNV resulted in an increase in splenic IL-17-producing γδT- and Th17-cells; yet in the CNV eye, only elevated levels of γδT-cells were observed. Systemic administration of anti-C5- or anti-C5a-blocking antibodies blunted the CNV-induced production of splenic Th17- and γδT-cells, reduced CNV size and eliminated ocular γδT-cell infiltration. In ARPE-19 cell monolayers, IL-17 triggered a pro-inflammatory state; and splenocyte proliferation was elevated in response to ocular proteins. Thus, we demonstrated that CNV lesions trigger a systemic immune response, augmenting local ocular inflammation via the infiltration of IL-17-producing γδT-cells, which are presumably recruited to the eye in a C5a-dependent manner. Understanding the complexity of complement-mediated pathological mechanisms will aid in the development of an AMD treatment. PMID:27029558

  20. Distinct associations of complement C3a and its precursor C3 with atherosclerosis and cardiovascular disease

    NARCIS (Netherlands)

    Hertle, E.; Greevenbroek, van M.M.J.; Arts, I.C.W.; Kallen, van der C.J.H.; Geijselaers, S.L.C.; Feskens, E.J.M.; Jansen, E.H.; Schalkwijk, C.G.; Stehouwer, C.D.A.


    Complement C3 is a novel risk factor for cardiovascular disease (CVD), but the underlying mechanism is currently unknown. We determined the associations of the anaphylatoxin C3a, the activation product of C3, and of C3 itself with estimates of atherosclerosis and CVD. We studied associations of C3a

  1. Gene : CBRC-HSAP-19-0100 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available iens] dbj|BAA95414.1| G protein-coupled receptor C5L2 [Homo sapiens] gb|AAP23197.1| C5A anap...23872 /ug=Hs.534412 /len=1287 0.0 100% C5a-des-Arg anaphylatoxin Gi/o,Gq/11 MGNDSVSYEYGDYSDLSDRPVDCLDGACLAIDPLRVAP...CBRC-HSAP-19-0100 19 A Chemokines and chemotactic factors receptors C5ARL_HUMAN 0.0... 100% ref|NP_060955.1| G protein-coupled receptor 77 [Homo sapiens] sp|Q9P296|C5ARL_HUMAN C5a anaphylatoxin ...chemotactic receptor C5L2 (G-protein coupled receptor 77) gb|AAK12640.1|AF317655_1 G protein-coupled receptor [Homo sap

  2. Gene : CBRC-HSAP-12-0004 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available 100% ref|NP_004045.1| complement component 3a receptor 1 [Homo sapiens] sp|Q16581|C3AR_HUMAN C3a chemotactic receptor (C3a-R) (C3AR) emb|CAA97504.1| C3a anaphylatoxin receptor [Homo sapiens] gb|AAH20742....1| Complement component 3a receptor 1 [Homo sapiens] dbj|BAC06088.1| seven trans...membrane helix receptor [Homo sapiens] gb|AAP23198.1| complement component 3a receptor 1 [Homo sapiens] gb|A...AR13862.1| complement component 3a receptor 1 [Homo sapiens] gb|EAW88640.1| complement component 3a receptor

  3. Interleukin 3 and granulocyte/macrophage-colony-stimulating factor render human basophils responsive to low concentrations of complement component C3a.


    Bischoff, S C; de Weck, A. L.; Dahinden, C A


    Complement component C3a is an anaphylatoxin known to induce plasma exudation and smooth muscle contraction in tissues. The effects on inflammatory effector leukocytes, however, are poorly defined and controversial, being at best weak and occurring at very high C3a concentrations. Here, we examined the effect of C3a upon mediator release from human basophils, with and without pretreatment with interleukin 3 (IL-3), a hematopoietic growth factor recently found to profoundly modify the basophil...

  4. Anaphylactic actions of platelet-activating factor.


    Stimler, N. P.; Bloor, C. M.; Hugli, T E; Wykle, R. L.; McCall, C E; O'Flaherty, J. T.


    Platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphorylcholine) is a potent inducer of systemic anaphylactoid reactions in animals. It was found to be similarly potent in contracting smooth muscle of guinea pig ileum and lung and in enhancing vascular permeability when injected subcutaneously into these animals. This factor, therefore, possesses in vitro and in vivo bioactions that resemble those of C3a and C5a anaphylatoxins. However, platelet-activating factor induces a slowl...

  5. N-formylpeptide and complement C5a receptors are expressed in liver cells and mediate hepatic acute phase gene regulation



    Although the classical chemotactic receptor for complement anaphylatoxin C5a has been associated with polymorphonuclear and mononuclear phagocytes, several recent studies have indicated that this receptor is expressed on nonmyeloid cells including human endothelial cells, vascular smooth muscle cells, bronchial and alveolar epithelial cells, hepatocytes, and in the human hepatoma cell line HepG2. In this study, we examined the possibility that other members of the chemotactic receptor family ...

  6. Structural and functional implications of the complement convertase stabilized by a staphylococcal inhibitor


    Rooijakkers, Suzan H.M.; Wu, Jin; Ruyken, Maartje; van Domselaar, Robert; Planken, Karel L.; Tzekou, Apostolia; Ricklin, Daniel; Lambris, John D.; Janssen, Bert J.C.; van Strijp, Jos A. G.; Gros, Piet


    Activation of the complement system generates potent chemoattractants and opsonizes cells for immune clearance. Short-lived protease complexes cleave complement component C3 into anaphylatoxin C3a and opsonin C3b. Here we report the crystal structure of the C3 convertase formed by C3b and the protease fragment Bb, which was stabilized by the bacterial immune-evasion protein SCIN. The data suggest that the proteolytic specificity and activity depends on dimerization of C3 with C3b of the conve...

  7. Complement C3: an emerging risk factor in cardiometabolic disease


    Hertle, E.; van Greevenbroek, M.M.J.; Stehouwer, C.D.A.


    C3 is the central component of the complement system and activation of C3 via any of the three major activation pathways—the classical, the lectin and the alternative pathways—results in initiation of the terminal complement pathway and release of the anaphylatoxin C3a. Both terminal pathway activation and signalling of C3a and its inactivation product C3a-desarg via the C3a receptor and C5a-like receptor 2, respectively, can induce inflammatory, immunomodulatory and metabolic responses. C3 h...

  8. Complement activation and HLA-B27.


    Meri, S.; Partanen, J; Leirisalo-Repo, M; Repo, H


    The efficiency of complement activation was studied in sera from HLA-B27 positive and negative subjects (27 with previous yersinia arthritis and 35 controls). Activation of complement with zymosan induced higher mean levels of the anaphylatoxin C3a in HLA-B27 positive sera (mean (SD) 7.40 (1.66) mg/l) than in HLA-B27 negative sera (6.41 (1.79) mg/l). Similarly, higher levels of C3d,g, another C3 breakdown fragment, were obtained in HLA-B27 positive sera after Escherichia coli 0111:B4 lipopoly...

  9. AcEST: DK946423 [AcEST

    Lifescience Database Archive (English)

    Full Text Available YMU02A01NGRL0012_J06 194 Adiantum capillus-veneris mRNA. clone: YMU02A01NGRL0012_J06. 5' end...finition sp|O70129|C5AR_CAVPO C5a anaphylatoxin chemotactic receptor OS=Cavia porcellus Align length 39 A. Schaffer, Jinghui Zhang, Zheng Zhang, Webb Miller, and David J. Lipman...ence: Altschul, Stephen F., Thomas L. Madden, Alejandro A. Schaffer, Jinghui Zhang, Zheng Zhang, Webb Miller, and David J. Lipman... sequence. DK946423 - Show DK946423 Clone id YMU02A01NGRL0012_J06 Library YMU02 Length 194 Definition Adian

  10. The C5a receptor impairs IL-12–dependent clearance of Porphyromonas gingivalis and is required for induction of periodontal bone loss1


    Liang, Shuang; Krauss, Jennifer L.; Domon, Hisanori; McIntosh, Megan L.; Hosur, Kavita B.; Qu, Hongchang; Li, Fenge; Tzekou, Apostolia; Lambris, John D.; Hajishengallis, George


    The C5a anaphylatoxin receptor (C5aR; CD88) is activated as part of the complement cascade and exerts important inflammatory, antimicrobial and regulatory functions, at least in part, via crosstalk with TLRs. However, the periodontal pathogen Porphyromonas gingivalis can control C5aR activation by generating C5a through its own C5 convertase-like enzymatic activity. Here we show that P. gingivalis uses this mechanism to proactively and selectively inhibit TLR2-induced IL-12p70, whereas the sa...

  11. Isolation of a thiol-dependent serine protease in peanut and investigation of its role in the complement and the allergic reaction. (United States)

    Javaux, Cédric; Stordeur, Patrick; Azarkan, Mohamed; Mascart, Françoise; Baeyens-Volant, Danielle


    A serine protease activity was detected in aqueous peanuts seeds extracts, partially purified and characterized as a thiol-dependent serine protease. The potential role of this proteolytic activity on allergic reaction to peanuts was prospected through complement activation studies in human plasma and serum, and MDCK cells to investigate a possible occludin degradation in tight junctions. The peanut protease activity induced the production of anaphylatoxins C3a and C5a, and of the terminal membrane attack complex SC5b-9 whatever the complement activation pathway. The protease activity was also involved in the partial digestion of occludin within tight junctions, with for result, an increase of the epithelial permeability to antigen absorption. PMID:27280846

  12. Decreased synthesis of serum carboxypeptidase N (SCPN) in familial SCPN deficiency

    Energy Technology Data Exchange (ETDEWEB)

    Mathews, K.P.; Curd, J.G.; Hugli, T.E.


    Serum carboxypeptidase N (SCPN) is the primary inactivator of the C3a, C4a, and C5a anaphylatoxins as well as an inactivator of bradykinin. Thus, SCPN deficiency potentially could result in significant pathophysiologic consequences. Previous studies identified a deficient subject afflicted with frequent episodes of angioedema, and other family members also had SCPN deficiency. To delineate this abnormality further, the fractional catabolic rate (FRC) and enzyme synthesis were determined in three members of the afflicted kindred as well as in five normal persons following the infusion of homogeneous /sup 125/I-SCPN. The mean FCR and synthesis rates for SCPN in the normal subjects were 1.3%/hr and 20,793 U/kg/hr, respectively. Reduced synthesis was concluded to be primarily responsible for the low SCPN levels in the afflicted kindred. The high FRC of SCPN discourages attempted maintenance therapy with infusions of enriched SCPN preparations.

  13. Decreased synthesis of serum carboxypeptidase N (SCPN) in familial SCPN deficiency

    International Nuclear Information System (INIS)

    Serum carboxypeptidase N (SCPN) is the primary inactivator of the C3a, C4a, and C5a anaphylatoxins as well as an inactivator of bradykinin. Thus, SCPN deficiency potentially could result in significant pathophysiologic consequences. Previous studies identified a deficient subject afflicted with frequent episodes of angioedema, and other family members also had SCPN deficiency. To delineate this abnormality further, the fractional catabolic rate (FRC) and enzyme synthesis were determined in three members of the afflicted kindred as well as in five normal persons following the infusion of homogeneous 125I-SCPN. The mean FCR and synthesis rates for SCPN in the normal subjects were 1.3%/hr and 20,793 U/kg/hr, respectively. Reduced synthesis was concluded to be primarily responsible for the low SCPN levels in the afflicted kindred. The high FRC of SCPN discourages attempted maintenance therapy with infusions of enriched SCPN preparations

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

    DEFF Research Database (Denmark)

    Bajic, Goran


    associated with microbes and apoptotic or necrotic cells. Complement not only protects against pathogens but also maintains body homeostasis. Activation of complement leads to cleavage of the complement proteins C4, C3 and C5, and their fragments have effector functions through binding to pathogen surfaces...... small 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....... An important outcome of the regulators is the degradation of C3b to iC3b. Phagocytic receptor αMβ2 integrin (also called CR3, CD11b/CD18, or Mac-1) on leukocytes engages the opsonized activator subsequently to C3b cleavage into iC3b. Apoptotic cells activate complement leading to iC3b deposition and...

  15. Complement system part I - molecular mechanisms of activation and regulation

    Directory of Open Access Journals (Sweden)

    Nicolas eMerle


    Full Text Available Complement is a complex innate immune surveillance system, playing a key role in defense against pathogens and in host homeostasis. The complement system is initiated by conformational changes in recognition molecular complexes upon sensing danger signals. The subsequent cascade of enzymatic reactions is tightly regulated to assure that complement is activated only at specific locations requiring defense against pathogens, thus avoiding host tissue damage. Here we discuss the recent advances describing the molecular and structural basis of activation and regulation of the complement pathways and their implication on physiology and pathology. This article will review the mechanisms of activation of alternative, classical and lectin pathways, the formation of C3 and C5 convertases, the action of anaphylatoxins and the membrane attack complex. We will also discuss the importance of structure-function relationships using the example of atypical hemolytic uremic syndrome. Lastly we will discuss the development and benefits of therapies using complement inhibitors.

  16. Alloantibody Generation and Effector Function Following Sensitization to Human Leukocyte Antigen (United States)

    Hickey, Michelle J.; Valenzuela, Nicole M.; Reed, Elaine F.


    Allorecognition is the activation of the adaptive immune system to foreign human leukocyte antigen (HLA) resulting in the generation of alloantibodies. Due to a high polymorphism, foreign HLA is recognized by the immune system following transplant, transfusion, or pregnancy resulting in the formation of the germinal center and the generation of long-lived alloantibody-producing memory B cells. Alloantibodies recognize antigenic epitopes displayed by the HLA molecule on the transplanted allograft and contribute to graft damage through multiple mechanisms, including (1) activation of the complement cascade resulting in the formation of the MAC complex and inflammatory anaphylatoxins, (2) transduction of intracellular signals leading to cytoskeletal rearrangement, growth, and proliferation of graft vasculature, and (3) immune cell infiltration into the allograft via FcγR interactions with the FC portion of the antibody. This review focuses on the generation of HLA alloantibody, routes of sensitization, alloantibody specificity, and mechanisms of antibody-mediated graft damage. PMID:26870045

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

    Directory of Open Access Journals (Sweden)

    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.

  18. Immune receptors and adhesion molecules in human pulmonary leptospirosis. (United States)

    Del Carlo Bernardi, Fabiola; Ctenas, Bruno; da Silva, Luiz Fernando Ferraz; Nicodemo, Antonio Carlos; Saldiva, Paulo Hilário Nascimento; Dolhnikoff, Marisa; Mauad, Thais


    Pulmonary involvement in leptospirosis has been increasingly reported in the last 20 years, being related to the severity and mortality of the disease. The pathogenesis of pulmonary hemorrhage in leptospirosis is not understood. Lung endothelial cells have been proposed as targets in the pathogenesis of lung involvement in leptospirosis through the activation of Toll-like receptor 2 or the complement system, which stimulates the release of cytokines that lead to the activation of adhesion molecules. The aim of this study was to investigate the involvement of immune pathways and of the intercellular and vascular cell adhesion molecules (intercellular adhesion molecule and vascular cell adhesion molecule, respectively) in the lungs of patients with pulmonary involvement of leptospirosis. We studied the lungs of 18 patients who died of leptospirosis and compared them with 2 groups of controls: normal and noninfectious hemorrhagic lungs. Using immunohistochemistry and image analysis, we quantified the expression of the C3a anaphylatoxin receptor, intercellular adhesion molecule, vascular cell adhesion molecule, and Toll-like receptor 2 in small pulmonary vessels and in the alveolar septa. There was an increased expression of intercellular adhesion molecule (P < .03) and C3a anaphylatoxin receptor (P < .008) in alveolar septa in the leptospirosis group compared with the normal and hemorrhagic controls. In the vessels of the leptospirosis group, there was an increased expression of intercellular adhesion molecule (P = .004), vascular cell adhesion molecule (P = .030), and Toll-like receptor 2 (P = .042) compared with the normal group. Vascular cell adhesion molecule expression in vessels was higher in the leptospirosis group compared with the hemorrhagic group (P = .015). Our results indicate that immune receptors and adhesion molecules participate in the phenomena leading to pulmonary hemorrhage in leptospirosis. PMID:22436623

  19. Complement activation-related pseudoallergy: a stress reaction in blood triggered by nanomedicines and biologicals. (United States)

    Szebeni, Janos


    Intravenous injection of a variety of nanotechnology enhanced (liposomal, micellar, polymer-conjugated) and protein-based (antibodies, enzymes) drugs can lead to hypersensitivity reactions (HSRs), also known as infusion, or anaphylactoid reactions. The molecular mechanism of mild to severe allergy symptoms may differ from case to case and is mostly not known, however, in many cases a major cause, or contributing factor is activation of the complement (C) system. The clinical relevance of C activation-related HSRs, a non-IgE-mediated pseudoallergy (CARPA), lies in its unpredictability and occasional lethal outcome. Accordingly, there is an unmet medical need to develop laboratory assays and animal models that quantitate CARPA. This review provides basic information on CARPA; a short history, issues of nomenclature, incidence, classification of reactogenic drugs and symptoms, and the mechanisms of C activation via different pathways. It is pointed out that anaphylatoxin-induced mast cell release may not entirely explain the severe reactions; a "second hit" on allergy mediating cells may also contribute. In addressing the increasing requirements for CARPA testing, the review evaluates the available assays and animal models, and proposes a possible algorithm for the screening of reactogenic drugs and hypersensitive patients. Finally, an analogy is proposed between CARPA and the classic stress reaction, suggesting that CARPA represents a "blood stress" reaction, a systemic fight of the body against harmful biological and chemical agents via the anaphylatoxin/mast-cell/circulatory system axis, in analogy to the body's fight of physical and emotional stress via the hypothalamo/pituitary/adrenal axis. In both cases the response to a broad variety of noxious effects are funneled into a uniform pattern of physiological changes. PMID:25124145

  20. Antagonism of the prostaglandin D2 receptor CRTH2 attenuates asthma pathology in mouse eosinophilic airway inflammation

    Directory of Open Access Journals (Sweden)

    Högberg Thomas


    Full Text Available Abstract Background Mast cell-derived prostaglandin D2 (PGD2, may contribute to eosinophilic inflammation and mucus production in allergic asthma. Chemoattractant receptor homologous molecule expressed on TH2 cells (CRTH2, a high affinity receptor for prostaglandin D2, mediates trafficking of TH2-cells, mast cells, and eosinophils to inflammatory sites, and has recently attracted interest as target for treatment of allergic airway diseases. The present study involving mice explores the specificity of CRTH2 antagonism of TM30089, which is structurally closely related to the dual TP/CRTH2 antagonist ramatroban, and compares the ability of ramatroban and TM30089 to inhibit asthma-like pathology. Methods Affinity for and antagonistic potency of TM30089 on many mouse receptors including thromboxane A2 receptor mTP, CRTH2 receptor, and selected anaphylatoxin and chemokines receptors were determined in recombinant expression systems in vitro. In vivo effects of TM30089 and ramatroban on tissue eosinophilia and mucus cell histopathology were examined in a mouse asthma model. Results TM30089, displayed high selectivity for and antagonistic potency on mouse CRTH2 but lacked affinity to TP and many other receptors including the related anaphylatoxin C3a and C5a receptors, selected chemokine receptors and the cyclooxygenase isoforms 1 and 2 which are all recognized players in allergic diseases. Furthermore, TM30089 and ramatroban, the latter used as a reference herein, similarly inhibited asthma pathology in vivo by reducing peribronchial eosinophilia and mucus cell hyperplasia. Conclusion This is the first report to demonstrate anti-allergic efficacy in vivo of a highly selective small molecule CRTH2 antagonist. Our data suggest that CRTH2 antagonism alone is effective in mouse allergic airway inflammation even to the extent that this mechanism can explain the efficacy of ramatroban.

  1. Increased interleukin-6 correlates with myelin oligodendrocyte glycoprotein antibodies in pediatric monophasic demyelinating diseases and multiple sclerosis. (United States)

    Horellou, Philippe; Wang, Min; Keo, Vixra; Chrétien, Pascale; Serguera, Ché; Waters, Patrick; Deiva, Kumaran


    Acquired demyelinating syndromes (ADS) in children evolve either as a monophasic disease diagnosed as acute demyelinating encephalomyelitis (ADEM), transverse myelitis (TM) or optic neuritis (ON), or a multiphasic one with several relapses most often leading to the diagnosis of multiple sclerosis (MS) or neuromyelitis optica (NMO). These neuroinflammatory disorders are increasingly associated with autoantibodies against proteins such as aquaporin-4 in rare instances, and more frequently against myelin oligodendrocyte glycoprotein (MOG). Recently, in adult NMO patients, C5a levels were shown to be elevated in cerebrospinal fluid (CSF) during acute exacerbation. We investigated the CSF levels of anaphylatoxins and pro-inflammatory cytokines, and plasma MOG antibodies in onset samples from children with ADS. Thirty four children presenting with a first episode of ADS, 17 with monophasic ADS (9 with ADEM, 4 with TM and 4 with ON) and 17 with MS, who had paired blood and CSF samples at onset were included and compared to 12 patients with other non-inflammatory neurological disorders (OND). Cytokines and anaphylatoxins in CSF were measured by Cytometric Bead Array immunoassay. MOG antibody titers in plasma were tested by flow cytometry using a stable cell line expressing full-length human MOG. We found a significant increase in C5a levels in the CSF of patients with monophasic ADS (n=17) compared to OND (n=12, p=0.0036) and to MS (n=17, p=0.0371). The C5a levels in MS were higher than in OND without reaching significance (p=0.2). CSF IL-6 levels were significantly increased in monophasic ADS compared to OND (p=0.0027) and to MS (p=0.0046). MOG antibody plasma levels were significantly higher in monophasic ADS (p<0.0001) and, to a lesser extent, in MS compared to OND (p=0.0023). Plasma MOG antibodies and CSF IL-6 levels were significantly correlated (r=0.51, p=0.018). CSF C5a and IL-6 levels are increased in monophasic ADS but not in MS when compared to OND, suggesting

  2. Innate immune induction and influenza protection elicited by a response-selective agonist of human C5a.

    Directory of Open Access Journals (Sweden)

    Sam D Sanderson

    Full Text Available The anaphylatoxin C5a is an especially potent mediator of both local and systemic inflammation. However, C5a also plays an essential role in mucosal host defense against bacterial, viral, and fungal infection. We have developed a response-selective agonist of human C5a, termed EP67, which retains the immunoenhancing activity of C5a at the expense of its inflammatory, anaphylagenic properties. EP67 insufflation results in the rapid induction of pulmonary cytokines and chemokines. This is followed by an influx of innate immune effector cells, including neutrophils, NK cells, and dendritic cells. EP67 exhibits both prophylactic and therapeutic protection when tested in a murine model of influenza A infection. Mice treated with EP67 within a twenty-four hour window of non-lethal infection were significantly protected from influenza-induced weight loss. Furthermore, EP67 delivered twenty-four hours after lethal infection completely blocked influenza-induced mortality (0% vs. 100% survival. Since protection based on innate immune induction is not restricted to any specific pathogen, EP67 may well prove equally efficacious against a wide variety of possible viral, bacterial, and fungal pathogens. Such a strategy could be used to stop the worldwide spread of emergent respiratory diseases, including but not limited to novel strains of influenza.

  3. Deficiency of the Complement Component 3 but Not Factor B Aggravates Staphylococcus aureus Septic Arthritis in Mice. (United States)

    Na, Manli; Jarneborn, Anders; Ali, Abukar; Welin, Amanda; Magnusson, Malin; Stokowska, Anna; Pekna, Marcela; Jin, Tao


    The complement system plays an essential role in the innate immune response and protection against bacterial infections. However, detailed knowledge regarding the role of complement in Staphylococcus aureus septic arthritis is still largely missing. In this study, we elucidated the roles of selected complement proteins in S. aureus septic arthritis. Mice lacking the complement component 3 (C3(-/-)), complement factor B (fB(-/-)), and receptor for C3-derived anaphylatoxin C3a (C3aR(-/-)) and wild-type (WT) control mice were intravenously or intra-articularly inoculated with S. aureus strain Newman. The clinical course of septic arthritis, as well as histopathological and radiological changes in joints, was assessed. After intravenous inoculation, arthritis severity and frequency were significantly higher in C3(-/-)mice than in WT controls, whereas fB(-/-)mice displayed intermediate arthritis severity and frequency. This was in accordance with both histopathological and radiological findings. C3, but not fB, deficiency was associated with greater weight loss, more frequent kidney abscesses, and higher bacterial burden in kidneys. S. aureus opsonized with C3(-/-)sera displayed decreased uptake by mouse peritoneal macrophages compared with bacteria opsonized with WT or fB(-/-)sera. C3aR deficiency had no effect on the course of hematogenous S. aureus septic arthritis. We conclude that C3 deficiency increases susceptibility to hematogenous S. aureus septic arthritis and impairs host bacterial clearance, conceivably due to diminished opsonization and phagocytosis of S. aureus. PMID:26787717

  4. Common evolutionary origin of alpha 2-macroglobulin and complement components C3 and C4

    DEFF Research Database (Denmark)

    Sottrup-Jensen, Lars; Stepanik, T M; Kristensen, Torsten;


    A comparison of the sequence of the subunit of human alpha 2-macroglobulin (alpha 2M; 1451 amino acid residues) with that of murine complement component pro-C3 (1639 amino acid residues) reveals eight extended regions of sequence similarity. These regions contain between 19% and 31% identically...... placed residues and account for 75% and 67%, respectively, of the polypeptide chains of alpha 2M and pro-C3. Published sequence data for complement component C4 show that segments of this protein match well with corresponding stretches in alpha 2M and pro-C3. It is proposed that alpha 2M, C3 and C4...... common gross structure. The quartets of basic residues in pro-C3 and pro-C4, at which cleavage takes place to produce the mature subunits of these proteins, and most of the residues forming the anaphylatoxin peptides of C3 and C4 (C3a and C4a) are absent in alpha 2M. In addition, C3 and C4 contain large...

  5. The structure of bovine complement component 3 reveals the basis for thioester function

    DEFF Research Database (Denmark)

    Fredslund, Folmer; Jenner, Lasse Bohl; Husted, Lise Bjerre;


    The third component of complement (C3) is a 190 kDa glycoprotein essential for eliciting the complement response. The protein consists of two polypeptide chains (α and β) held together with a single disulfide bridge. The β-chain is made up of six MG domains of which one of which is shared with the...... α-chain. The disulfide bridge connecting the chains is positioned in the shared MG domain. The α-chain consists of the anaphylatoxin domain, three MG domains, a CUB domain, an α6/α6-barrel domain and the C-terminal C345c domain. An internal thioester in the α-chain of C3 (also present in C4 but not...... in C5) is cleaved during complement activation. This mediates covalent attachment of the activated C3b to immune complexes and invading microorganisms hereby opsonising the target. We present the structure of bovine C3 determined at 3 Å resolution. The structure shows that the ester is deeply buried...

  6. Role of C5 Activation Products in Sepsis

    Directory of Open Access Journals (Sweden)

    Peter A. Ward


    Full Text Available Complement activation products are known to be generated in the setting of both experimental and human sepsis. C5 activation products (C5a anaphylatoxin and the membrane attack complex [MAC] C5b-9 are generated during sepsis following infusion of endotoxin, or after cecal ligation and puncture (CLP, which produces polymicrobial sepsis. C5a reacts with its receptors C5aR and C5L2 in a manner that creates the “cytokine storm”, and is associated with development of multiorgan failure (MOF. A number of other complications arising from the interaction of C5a with its receptors include apoptosis of lymphoid cells, loss of innate immune functions of neutrophils (PMNs, polymorphonuclear leukocytes, cardiomyopathy, disseminated intravascular coagulation, and complications associated with MOF. Neutralization of C5a in vivo or absence/blockade of C5a receptors greatly reduces the adverse events in the setting of sepsis, markedly attenuates MOF, and greatly improves survival. Regarding the possible role of C5b-9 in sepsis, the literature is conflicting. Some studies suggest that C5b-9 is protective, while other studies suggest the contrary. Clearly, in human sepsis, C5a and its receptors may be logical targets for interception.

  7. Complement profile and activation mechanisms by different LDL apheresis systems. (United States)

    Hovland, Anders; Hardersen, Randolf; Nielsen, Erik Waage; Enebakk, Terje; Christiansen, Dorte; Ludviksen, Judith Krey; Mollnes, Tom Eirik; Lappegård, Knut Tore


    Extracorporeal removal of low-density lipoprotein (LDL) cholesterol by means of selective LDL apheresis is indicated in otherwise uncontrolled familial hypercholesterolemia. During blood-biomaterial interaction other constituents than the LDL particles are affected, including the complement system. We set up an ex vivo model in which human whole blood was passed through an LDL apheresis system with one of three different apheresis columns: whole blood adsorption, plasma adsorption and plasma filtration. The concentrations of complement activation products revealed distinctly different patterns of activation and adsorption by the different systems. Evaluated as the final common terminal complement complex (TCC) the whole blood system was inert, in contrast to the plasma systems, which generated substantial and equal amounts of TCC. Initial classical pathway activation was revealed equally for both plasma systems as increases in the C1rs-C1inh complex and C4d. Alternative pathway activation (Bb) was most pronounced for the plasma adsorption system. Although the anaphylatoxins (C3a and C5a) were equally generated by the two plasma separation systems, they were efficiently adsorbed to the plasma adsorption column before the "outlet", whereas they were left free in the plasma in the filtration system. Consequently, during blood-biomaterial interaction in LDL apheresis the complement system is modulated in different manners depending on the device composition. PMID:22373816

  8. Animal models of complement-mediated hypersensitivity reactions to liposomes and other lipid-based nanoparticles. (United States)

    Szebeni, János; Alving, Carl R; Rosivall, László; Bünger, Rolf; Baranyi, Lajos; Bedöcs, Péter; Tóth, Miklós; Barenholz, Yezheckel


    Intravenous injection of some liposomal drugs, diagnostic agents, micelles and other lipid-based nanoparticles can cause acute hypersensitivity reactions (HSRs) in a high percentage (up to 45%) of patients, with hemodynamic, respiratory and cutaneous manifestations. The phenomenon can be explained with activation of the complement (C) system on the surface of lipid particles, leading to anaphylatoxin (C5a and C3a) liberation and subsequent release reactions of mast cells, basophils and possibly other inflammatory cells in blood. These reactions can be reproduced and studied in pigs, dogs and rats, animal models which differ from each other in sensitivity and spectrum of symptoms. In the most sensitive pig model, a few miligrams of liposome (phospholipid) can cause anaphylactoid shock, characterized by pulmonary hypertension, systemic hypotension, decreased cardiac output and major cardiac arrhythmias. Pigs also display cutaneous symptoms, such as flushing and rash. The sensitivity of dogs to hemodynamic changes is close to that of pigs, but unlike pigs, dogs also react to micellar lipids (such as Cremophor EL) and their response includes pronounced blood cell and vegetative neural changes (e.g., leukopenia followed by leukocytosis, thrombocytopenia, fluid excretions). Rats are relatively insensitive inasmuch as hypotension, their most prominent response to liposomes, is induced only by one or two orders of magnitude higher phospholipid doses (based on body weight) compared to the reactogenic dose in pigs and dogs. It is suggested that the porcine and dog models are applicable for measuring and predicting the (pseudo)allergic activity of particulate "nanodrugs". PMID:17613700

  9. Complement C5a-C5aR interaction enhances MAPK signaling pathway activities to mediate renal injury in trichloroethylene sensitized BALB/c mice. (United States)

    Zhang, Jia-xiang; Zha, Wan-sheng; Ye, Liang-ping; Wang, Feng; Wang, Hui; Shen, Tong; Wu, Chang-hao; Zhu, Qi-xing


    We have previously shown complement activation as a possible mechanism for trichloroethylene (TCE) sensitization, leading to multi-organ damage including the kidneys. In particular, excessive deposition of C5 and C5b-9-the membrane attack complex, which can generate significant tissue damage, was observed in the kidney tissue after TCE sensitization. The present study tested the hypothesis that anaphylatoxin C5a binding to its receptor C5aR mediates renal injury in TCE-sensitized BALB/c mice. BALB/c mice were sensitized through skin challenge with TCE, with or without pretreatment by the C5aR antagonist W54011. Kidney histopathology and the renal functional test were performed to assess renal injury, and immunohistochemistry and fluorescent labeling were carried out to assess C5a and C5aR expressions. TCE sensitization up-regulated C5a and C5aR expressions in kidney tissue, generated inflammatory infiltration, renal tubule damage, glomerular hypercellularity and impaired renal function. Antagonist pretreatment blocked C5a binding to C5aR and attenuated TCE-induced tissue damage and renal dysfunction. TCE sensitization also caused the deposition of major pro-inflammatory cytokines IL-2, TNF-α and IFN-γ in the kidney tissue (P TCE sensitization-induced increase of IL-2, TNF-α and IFN-γ (P TCE or other environmental chemicals. PMID:26095957

  10. Isolation and sequence analysis of a cDNA clone encoding the fifth complement component

    DEFF Research Database (Denmark)

    Lundwall, Åke B; Wetsel, Rick A; Kristensen, Torsten;


    clone of 1.85 kilobase pairs was isolated. Hybridization of the mixed-sequence probe to the complementary strand of the plasmid insert and sequence analysis by the dideoxy method predicted the expected protein sequence of C5a (positions 1-12), amino-terminal to the anticipated priming site. The sequence......We have used available protein sequence data for the anaphylatoxin (C5a) portion of the fifth component of human complement (residues 19-25) to synthesize a mixed-sequence oligonucleotide probe. The labeled oligonucleotide was then used to screen a human liver cDNA library, and a single candidate cDNA...... obtained further predicted an arginine-rich sequence (RPRR) immediately upstream of the N-terminal threonine of C5a, indicating that the promolecule form of C5 is synthesized with a beta alpha-chain orientation as previously shown for pro-C3 and pro-C4. The C5 cDNA clone was sheared randomly by sonication...

  11. Modern Radiobiology: Contention Of Concepts: Advanced Technology And Development Of Effective Prophylaxis, Prevention And Treatment Of Biological Consequences After Irradiation. (United States)

    Popov, Dmitri; Maliev, Vecheslav; Jones, Jeffrey

    "Alle Ding' sind Gift, und nichts ohn' Gift; allein die Dosis macht, daß ein Ding kein Gift ist." Paracelsus Philippus Aureolus Theophrastus Bombastus von Hohenheim. Key worlds: Apoptosis, Necrosis, Domains associated with Cell Death, Caspase (catalytic) Domains, Death Domains (DDs), Death Effector Domains (DEDs), Caspase-Associated Recruitment Domains (CARDs, BIR Domains (IAPs), Bcl-2 Homology (BH) Domains, death ligands - TRAIL (TNF-Related Apoptosis-Inducing Ligand), FasL (Fas Ligand), TNFalpha (Tumor Necrosis Factor alpha), Toll-like receptors (TLR), Systemic inflammatory response syndrome (SIRS), Toxic Multiple Organ Injury (TMOI), Toxic Multiple Organ Dysfunction Syndromes (TMODS), Toxic Multiple Organ Failure (TMOF), Anaphylatoxins, or complement peptides; membrane attack complex (MAC), ROS - Reactive Oxygen Species; ASMase, acid sphingomyelinase; Neurotoxins, Cytotoxins, Haemotoxins. Introduction: Radiation affects many cell structures, organelles and metabolic pathways. Different doses and types of radiation ( gamma-radiation, neutron, heavy ion radiation) progress to reversible and irreversible forms of cell injury. Consideration: Apoptosis and Necrosis, major forms of post-radiation cell death, can be initiated and modulated by programmed control and proceed by similar or different pathways.[Akadi et al.,1993, Dunlacht J., et al. 1999] Radiation induced cell death by triggering apoptosis pathways was described in many articles and supported by many scientists. [Rio et al. 2002, Rakesh et al. 1997.] However some authors present results that two distinct pathways can initiate or apoptotic or necrotic responses: the death receptors and mitochondrial pathways.

  12. Macrophage Matrix Metalloproteinase-12 Dampens Inflammation and Neutrophil Influx in Arthritis

    Directory of Open Access Journals (Sweden)

    Caroline L. Bellac


    Full Text Available Resolution of inflammation reduces pathological tissue destruction and restores tissue homeostasis. Here, we used a proteomic protease substrate discovery approach, terminal amine isotopic labeling of substrates (TAILS, to analyze the role of the macrophage-specific matrix metalloproteinase-12 (MMP12 in inflammation. In murine peritonitis, MMP12 inactivates antithrombin and activates prothrombin, prolonging the activated partial thromboplastin time. Furthermore, MMP12 inactivates complement C3 to reduce complement activation and inactivates the chemoattractant anaphylatoxins C3a and C5a, whereas iC3b and C3b opsonin cleavage increases phagocytosis. Loss of these anti-inflammatory activities in collagen-induced arthritis in Mmp12−/− mice leads to unresolved synovitis and extensive articular inflammation. Deep articular cartilage loss is associated with massive neutrophil infiltration and abnormal DNA neutrophil extracellular traps (NETs. The NETs are rich in fibrin and extracellular actin, which TAILS identified as MMP12 substrates. Thus, macrophage MMP12 in arthritis has multiple protective roles in countering neutrophil infiltration, clearing NETs, and dampening inflammatory pathways to prepare for the resolution of inflammation.

  13. A New Experimental Polytrauma Model in Rats: Molecular Characterization of the Early Inflammatory Response

    Directory of Open Access Journals (Sweden)

    Sebastian Weckbach


    Full Text Available Background. The molecular mechanisms of the immune response after polytrauma are highly complex and far from fully understood. In this paper, we characterize a new standardized polytrauma model in rats based on the early molecular inflammatory and apoptotic response. Methods. Male Wistar rats (250 g, 6–10/group were anesthetized and exposed to chest trauma (ChT, closed head injury (CHI, or Tib/Fib fracture including a soft tissue trauma (Fx + STT or to the following combination of injuries: (1 ChT; (2 ChT + Fx + STT; (3 ChT + CHI; (4 CHI; (5 polytrauma (PT = ChT + CHI + Fx + STT. Sham-operated rats served as negative controls. The inflammatory response was quantified at 2 hours and 4 hours after trauma by analysis of “key” inflammatory mediators, including selected cytokines and complement components, in serum and bronchoalveolar (BAL fluid samples. Results. Polytraumatized (PT rats showed a significant systemic and intrapulmonary release of cytokines, chemokines, and complement anaphylatoxins, compared to rats with isolated injuries or selected combinations of injuries. Conclusion. This new rat model appears to closely mimic the early immunological response of polytrauma observed in humans and may provide a valid basis for evaluation of the complex pathophysiology and future therapeutic immune modulatory approaches in experimental polytrauma.

  14. Labeling the granulocyte C5a receptor with a unique photoreactive probe

    International Nuclear Information System (INIS)

    Human C5a anaphylatoxin is a complement-derived chemotactic factor that binds to specific receptors that are found in the granulocyte plasma membrane. These receptors, or a specific subunit of these receptors, can be covalently labeled with a unique photoreactive analog of human C5a. This photoaffinity probe, p-azidobenzoyl-2-mercapto-N-ethylamide-C5a (ABMEA-SC5a), was synthesized by coupling p-azidobenzoyl-2-mercapto-N-ethylamide-2'-thiopyridine disulfide to human C5a after it had been partially reduced with dithiothreitol. Both direct and competitive binding studies demonstrated that a radioiodinated ABMEA-SC5a derivative retained the capacity to specifically bind to either neutrophil or U937 cell C5a receptors. Half-maximal binding of the photoreactive analog was observed at a concentration of 1 to 2 nM, a value that is comparable to that observed when 125I-C5a is employed as the ligand. The covalent adducts that were formed after irradiation of 125I-ABMEA-SC5a that had been prebound to either neutrophil or U937 cell plasma membranes were found to have an apparent molecular mass of 52,000 daltons when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis techniques. These findings demonstrate that the C5a receptors found on human neutrophils and other granulocytes are not only functionally similar, but biochemically similar as well

  15. Decoration of heparin and bovine serum albumin on polysulfone membrane assisted via polydopamine strategy for hemodialysis. (United States)

    Xie, Bingwu; Zhang, Ranran; Zhang, Huan; Xu, Anxiu; Deng, Yi; Lv, Yalin; Deng, Feng; Wei, Shicheng


    Renal failure brings about abnormality of waste and toxins and deposition in the body. In clinic, the waste and toxins in vitro are eliminated by hemodialysis device with polysulfone (PSF) porous membranes. In the work, decoration of heparin (Hep) and bovine serum albumin (BSA) on PSF membranes would be beneficial to improve the hemocompatibility and reduce the anaphylatoxin formation during hemodialysis. The PSF porous membranes are surface-modified by simply dipping them into dopamine aqueous solution for 8 h. Then, Hep and BSA are immobilized covalently onto the resultant membrane. Attenuated total reflectance Fourier transform infrared spectra (ATR-FTIR) confirms that Hep and BSA are successfully introduced onto the surface of PSF membranes. Scanning electronic microscopy (SEM) and atomic force microscopy (AFM) display the changes of surface morphologies after modification. The result of water contact angle measurement shows that the hydrophilicity of PSF membranes is remarkably improved after coating polydopamine (pDA) and binding Hep and BSA. The experiments of hemocompatibility indicate that Hep and BSA grafted onto membranes suppress the adhesion of platelet and enhance the anticoagulation ability of PSF membranes. Furthermore, the protein adsorption tests reveal that Hep and BSA immobilized onto membranes depress the protein absorption and develop antifouling-protein ability of pristine membrane. This study proves a convenient and simple approach to graft two functional organic polymers which, respectively, play a vital role and then improve the hemocompatibility and biocompatibility of PSF membranes for their biomedical and blood-contacting applications. PMID:27018964

  16. Biocompatibility of surfactant-templated polyurea-nanoencapsulated macroporous silica aerogels with plasma platelets and endothelial cells. (United States)

    Yin, Wei; Venkitachalam, Subramaniam M; Jarrett, Ellen; Staggs, Sarah; Leventis, Nicholas; Lu, Hongbing; Rubenstein, David A


    The recently synthesized polyurea-nanoencapsulated surfactant-templated aerogels (X-aerogels) are porous materials with significantly improved mechanical strengths. Surface-wise they resemble polyurethane, a common biocompatible material, but their biocompatibility has never been investigated. As lightweight and strong materials, if X-aerogels also have acceptable biocompatibility, they may be used in many implantable devices. The goal of this study was to investigate their biocompatibility toward platelets, blood plasma, and vascular endothelial cells, in terms of cell activation and inflammatory responses. Platelets were incubated with X-aerogel and platelet activation was measured through CD62P and phosphatidylserine expression. Platelet aggregation was also measured. Contact with X-aerogel did not induce platelet activation or impair aggregation. To determine X-aerogel-induced inflammation, plasma anaphylatoxin C3a level was measured after incubation with X-aerogel. Results showed that X-aerogel induced no changes in plasma C3a levels. SEM and SDS-PAGE were used to examine cellular/protein deposition on X-aerogel samples after plasma incubation. No structural change or organic deposition was detected. Furthermore, X-aerogel samples did not induce any significant changes in vascular endothelial cell culture parameters after 5 days of incubation. These observations suggest that X-aerogels have a suitable biocompatibility toward platelets, plasma, and vascular endothelial cells, and they have potential for use in blood implantable devices. PMID:19358258

  17. Functional Identification of the Stable Transfection C5aR Cell Line Molt-4

    Institute of Scientific and Technical Information of China (English)

    Chunmei Zhang; Yan Li; Ruonan Xu; Jianan Wang; Gencheng Han; Guojiang Chen; Renxi Wang; Huawei Wei; Beifen Shen; Yuanfang Ma


    The complement C5 anaphylatoxin receptor is a member of the seven transmembrane-spanning G protein-coupled receptor superfamily that signals through Gαi and Gα16. C5aR is mostly expressed on neutrophils, macrophages and endothelial cells. C5a and C5aR interaction plays an important role in numerous biological effects such as in vivo cytokine storm which results in inflammatory damage. Considering the limitation of collection of human peripheral blood neutrophils and their short half life, the stably transfected cell line for studying the biological effects of C5aR is needed. In this study, we transfected C5aR gene into Molt-4 cell line and examined the function of ectopic C5aR. Our results showed stable expression of the C5aR in Molt-4 cell line and their interaction with human C5a induced ERK1/2 phosphorylation, Ca++ influx. This stable transfected cell line may provide a useful tool for studying signal pathways related to C5a and C5aR interplay and antibody development specific for C5aR.


    Directory of Open Access Journals (Sweden)

    Franca Orsini


    Full Text Available The immune response after brain injury is highly complex and involves both local and systemic events at the cellular and molecular level. It is associated to a dramatic over-activation of enzyme systems, the expression of proinflammatory genes and the activation/recruitment of immune cells. The complement system represents a powerful component of the innate immunity and is highly involved in the inflammatory response. Complement components are synthesized predominantly by the liver and circulate in the bloodstream primed for activation. Moreover, brain cells can produce complement proteins and receptors. After acute brain injury, the rapid and uncontrolled activation of the complement leads to massive release of inflammatory anaphylatoxins, recruitment of cells to the injury site, phagocytosis and induction of blood brain barrier damage. Brain endothelial cells are particularly susceptible to complement-mediated effects, since they are exposed to both circulating and locally synthesized complement proteins. Conversely, during neurodegenerative disorders, complement factors play distinct roles depending on the stage and degree of neuropathology. In addition to the deleterious role of the complement, increasing evidence suggest that it may also play a role in normal nervous system development (wiring the brain and adulthood (either maintaining brain homeostasis or supporting regeneration after brain injury. This article represents a compendium of the current knowledge on the complement role in the brain, prompting a novel view that complement activation can result in either protective or detrimental effects in brain conditions that depend exquisitely on the nature, the timing and the degree of the stimuli that induce its activation. A deeper understanding of the acute, subacute and chronic consequences of complement activation is needed and may lead to new therapeutic strategies, including the ability of targeting selective step in the complement

  19. Roles for NHERF1 and NHERF2 on the regulation of C3a receptor signaling in human mast cells.

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    Hariharan Subramanian

    Full Text Available BACKGROUND: The anaphylatoxin C3a binds to the G protein coupled receptor (GPCR, C3aR and activates divergent signaling pathways to induce degranulation and cytokine production in human mast cells. Adapter proteins such as the Na(+/H(+ exchange regulatory factor (NHERF1 and NHERF2 have been implicated in regulating functions of certain GPCRs by binding to the class I PDZ (PSD-95/Dlg/Zo1 motifs present on their cytoplasmic tails. Although C3aR possesses a class I PDZ motif, the possibility that it interacts with NHERF proteins to modulate signaling in human mast cells has not been determined. METHODOLOGY/PRINCIPAL FINDINGS: Using reverse transcription PCR and Western blotting, we found that NHERF1 and NHERF2 are expressed in human mast cell lines (HMC-1, LAD2 and CD34(+-derived primary human mast cells. Surprisingly, however, C3aR did not associate with these adapter proteins. To assess the roles of NHERFs on signaling downstream of C3aR, we used lentiviral shRNA to stably knockdown the expression of these proteins in human mast cells. Silencing the expression of NHERF1 and NHERF2 had no effect on C3aR desensitization, agonist-induced receptor internalization, ERK/Akt phosphorylation or chemotaxis. However, loss of NHERF1 and NHERF2 resulted in significant inhibition of C3a-induced mast cell degranulation, NF-κB activation and chemokine production. CONCLUSION/SIGNIFICANCE: This study demonstrates that although C3aR possesses a class I PDZ motif, it does not associate with NHERF1 and NHERF2. Surprisingly, these proteins provide stimulatory signals for C3a-induced degranulation, NF-κB activation and chemokine generation in human mast cells. These findings reveal a new level of complexity for the functional regulation of C3aR by NHERFs in human mast cells.

  20. Searching for early breast cancer biomarkers by serum protein profiling of pre-diagnostic serum; a nested case-control study

    International Nuclear Information System (INIS)

    Serum protein profiles have been investigated frequently to discover early biomarkers for breast cancer. So far, these studies used biological samples collected at or after diagnosis. This may limit these studies' value in the search for cancer biomarkers because of the often advanced tumor stage, and consequently risk of reverse causality. We present for the first time pre-diagnostic serum protein profiles in relation to breast cancer, using the Prospect-EPIC (European Prospective Investigation into Cancer and nutrition) cohort. In a nested case-control design we compared 68 women diagnosed with breast cancer within three years after enrollment, with 68 matched controls for differences in serum protein profiles. All samples were analyzed with SELDI-TOF MS (surface enhanced laser desorption/ionization time-of-flight mass spectrometry). In a subset of 20 case-control pairs, the serum proteome was identified and relatively quantified using isobaric Tags for Relative and Absolute Quantification (iTRAQ) and online two-dimensional nano-liquid chromatography coupled with tandem MS (2D-nanoLC-MS/MS). Two SELDI-TOF MS peaks with m/z 3323 and 8939, which probably represent doubly charged apolipoprotein C-I and C3a des-arginine anaphylatoxin (C3adesArg), were higher in pre-diagnostic breast cancer serum (p = 0.02 and p = 0.06, respectively). With 2D-nanoLC-MS/MS, afamin, apolipoprotein E and isoform 1 of inter-alpha trypsin inhibitor heavy chain H4 (ITIH4) were found to be higher in pre-diagnostic breast cancer (p < 0.05), while alpha-2-macroglobulin and ceruloplasmin were lower (p < 0.05). C3adesArg and ITIH4 have previously been related to the presence of symptomatic and/or mammographically detectable breast cancer. We show that serum protein profiles are already altered up to three years before breast cancer detection

  1. Crucial role of IL1beta and C3a in the in vitro-response of multipotent mesenchymal stromal cells to inflammatory mediators of polytrauma.

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    Nina-Emily Hengartner

    Full Text Available Multipotent mesenchymal stromal cells (MSC exert immune-modulatory effects and support tissue regeneration in various local trauma models. In case of a polytrauma, high amounts of danger-associated molecular patterns are released, leading to a systemic increase of inflammatory mediators. The influence of such a complex inflammatory microenvironment on human MSC is mainly unknown so far. Therefore, we investigated the effects of a defined serum-free polytrauma "cocktail" containing IL beta, IL6, IL8 and the anaphylatoxins C3a and C5a, in concentrations corresponding to those measured in the blood of polytrauma patients, on human MSC in vitro. The polytrauma cocktail induced directed migration of MSC with C3a representing its major soluble chemoattractive agent. Furthermore, the polytrauma cocktail and IL1beta upregulated the expression of MMP1 indicating a potential role of IL1beta to enhance MSC migration in the tissue context. COX2, PTGES and TSG6 were also found to be upregulated upon stimulation with the polytrauma cocktail or IL1beta, but not through other single factors of the polytrauma cocktail in pathophysiologically relevant concentrations. An RNA expression array of 84 inflammation-related genes revealed that both the polytrauma cocktail and IL1beta induced C3, CSF1, TLR3 and various chemokines without major qualitative or quantitative differences. These results indicate that IL1beta is a crucial mediator of the polytrauma cocktail in terms of immune-modulation and MMP1 expression. Thus, upon encountering the primary sterile, inflammatory milieu of a polytrauma, endogenous or systemically transfused MSC might be able to migrate to sites of injury, secrete TSG6 and PGE2 and to influence macrophage biology as observed in local trauma models.

  2. Effective suppression of C5a-induced proinflammatory response using anti-human C5a repebody. (United States)

    Hwang, Da-Eun; Choi, Jung-Min; Yang, Chul-Su; Lee, Joong-Jae; Heu, Woosung; Jo, Eun-Kyeong; Kim, Hak-Sung


    The strongest anaphylatoxin, C5a, plays a critical role in the proinflammatory responses, causing the pathogenesis of a number of inflammatory diseases including sepsis, asthma, and rheumatoid arthritis. Inhibitors of C5a thus have great potential as therapeutics for various inflammatory disorders. Herein, we present the development of a high-affinity repebody against human C5a (hC5a), which effectively suppresses the proinflammatory response. A repebody scaffold composed of leucine-rich repeat (LRR) modules was previously developed as an alternative protein scaffold. A repebody specifically binding to hC5a was selected through a phage display, and its affinity was increased up to 5 nM using modular engineering. The repebody was shown to effectively inhibit the production of C5a-induced proinflammatory cytokines by human monocytes. To obtain insight into a mode of action by the repebody, we determined its crystal structure in complex with hC5a. A structural analysis revealed that the repebody binds to the D1 and D3 regions of hC5a, overlapping several epitope residues with the hC5a receptor (hC5aR). It is thus likely that the repebody suppresses the hC5a-mediated immune response in monocytes by blocking the binding of hC5a to its receptor. The anti-hC5a repebody can be developed as a potential therapeutic for C5a-involved inflammatory diseases. PMID:27416759

  3. LDL apheresis and inflammation--implications for atherosclerosis. (United States)

    Hovland, A; Lappegård, K T; Mollnes, T E


    Low-density lipoprotein (LDL) apheresis is an extracorporeal treatment modality used in high-risk patients when LDL cholesterol levels cannot be reduced adequately with medication. The treatment is highly effective, but could be affected by potential unwanted effects on pro- and anti-inflammatory biomarkers. In this paper, we review the literature regarding the effect of LDL apheresis on pro- and anti-inflammatory biomarkers important in atherosclerosis, also as patients in LDL apheresis have high risk for atherosclerotic complications. We discuss the effect of LDL apheresis on complement, cytokines and finally a group of other selected pro- and anti-inflammatory biomarkers. The complement system is affected by LDL apheresis, and there are differences between different LDL apheresis systems. The plasma separation columns seem to trigger the formation of proinflammatory complement factors including C3a and C5a, while the same anaphylatoxins are adsorbed by the LDL apheresis columns, however, to varying degree. Proinflammatory cytokines are to some extent adsorbed by the LDL apheresis columns, while some of the anti-inflammatory cytokines increase during treatment. Finally, we discuss the effect of apheresis on different biomarkers including C-reactive protein, fibrinogen, adhesion molecules, myeloperoxidase and HDL cholesterol. In conclusion, even if there are differences between pro- and anti-inflammatory biomarkers during LDL apheresis, the consequences for the patients are largely unknown and larger studies need to be performed. Preferably, they should be comparing the effect of different LDL apheresis columns on the total inflammatory profile, and this should be related to clinical endpoints. PMID:22670805

  4. Structure of Complement C3(H2O) Revealed By Quantitative Cross-Linking/Mass Spectrometry And Modeling* (United States)

    Pellarin, Riccardo; Sali, Andrej; Barlow, Paul N.


    The slow but spontaneous and ubiquitous formation of C3(H2O), the hydrolytic and conformationally rearranged product of C3, initiates antibody-independent activation of the complement system that is a key first line of antimicrobial defense. The structure of C3(H2O) has not been determined. Here we subjected C3(H2O) to quantitative cross-linking/mass spectrometry (QCLMS). This revealed details of the structural differences and similarities between C3(H2O) and C3, as well as between C3(H2O) and its pivotal proteolytic cleavage product, C3b, which shares functionally similarity with C3(H2O). Considered in combination with the crystal structures of C3 and C3b, the QCMLS data suggest that C3(H2O) generation is accompanied by the migration of the thioester-containing domain of C3 from one end of the molecule to the other. This creates a stable C3b-like platform able to bind the zymogen, factor B, or the regulator, factor H. Integration of available crystallographic and QCLMS data allowed the determination of a 3D model of the C3(H2O) domain architecture. The unique arrangement of domains thus observed in C3(H2O), which retains the anaphylatoxin domain (that is excised when C3 is enzymatically activated to C3b), can be used to rationalize observed differences between C3(H2O) and C3b in terms of complement activation and regulation. PMID:27250206

  5. The relationship of interacting immunological components in dengue pathogenesis

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    Nielsen David G


    Full Text Available Abstract The World Health Organization (WHO estimates that there are over 50 million cases of dengue fever reported annually and approximately 2.5 billion people are at risk. Mild dengue fever presents with headache, fever, rash, myalgia, osteogenic pain, and lethargy. Severe disease can manifest as dengue shock syndrome (DSS or dengue hemorrhagic fever (DHF. Symptoms of DSS/DHF are leukopenia, low blood volume and pressure encephalitis, cold and sweaty skin, gastrointestinal bleeding, and spontaneous bleeding from gums and nose. Currently, there are no therapeutics available beyond supportive care and untreated complicated dengue fever can have a 50% mortality rate. According to WHO DSS/DHF is the leading cause of childhood mortality in some Asian countries. Dendritic cells are professional antigen presenting cells that are primary targets in a dengue infection. Dengue binds to Dendritic Cell-Specific Intercellular adhesion molecule-3-Grabbing Non-integrin (DC-SIGN. DC-SIGN has a high affinity for ICAM3 which is expressed in activating T-cells. Previous studies have demonstrated an altered T-cell phenotype expressed in dengue infected patients that could be potentially mediated by dengue-infected DCs. Dengue is enhanced by three interacting components of the immune system. Dengue begins by infecting dendritic cells which in immature dendritic cells is mediated by DC-SIGN. In mature dendritic cells, antibodies can enhance dengue infection via Fc receptors. Downstream of dendritic cells T-cells become activated and generate the very cytokines implicated in vascular leak and shock in addition to activating effector cells. Both the virus and the antibodies are involved in release of complement and anaphylatoxins which can cause or exacerbate DHF/DSS. These systems are inextricable and strongly associated with dengue pathogenesis.

  6. Differential Contributions of the Complement Anaphylotoxin Receptors C5aR1 and C5aR2 to the Early Innate Immune Response against Staphylococcus aureus Infection

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    Sarah A. Horst


    Full Text Available The complement anaphylatoxin C5a contributes to host defense against Staphylococcus aureus. In this study, we investigated the functional role of the two known C5a receptors, C5aR1 and C5aR2, in the host response to S. aureus. We found that C5aR1−/− mice exhibited greater susceptibility to S. aureus bloodstream infection than wild type and C5aR2−/− mice, as demonstrated by the significantly higher bacterial loads in the kidneys and heart at 24 h of infection, and by the higher levels of inflammatory IL-6 in serum. Histological and immunohistochemistry investigation of infected kidneys at 24 h after bacterial inoculation revealed a discrete infiltration of neutrophils in wild type mice but already well-developed abscesses consisting of bacterial clusters surrounded by a large number of neutrophils in both C5aR1−/− and C5aR2−/− mice. Furthermore, blood neutrophils from C5aR1−/− mice were less efficient than those from wild type or C5aR2−/− mice at killing S. aureus. The requirement of C5aR1 for efficient killing of S. aureus was also demonstrated in human blood after disrupting C5a-C5aR1 signaling using specific inhibitors. These results demonstrated a role for C5aR1 in S. aureus clearance as well as a role for both C5aR1 and C5aR2 in the orchestration of the inflammatory response during infection.

  7. An Inhibitor of the Alternative Pathway of Complement in Saliva of New World Anopheline Mosquitoes. (United States)

    Mendes-Sousa, Antonio F; Queiroz, Daniel C; Vale, Vladimir F; Ribeiro, José M C; Valenzuela, Jesus G; Gontijo, Nelder F; Andersen, John F


    The complement system present in circulating blood is an effective mechanism of host defense, responsible for the killing of pathogens and the production of potent anaphylatoxins. Inhibitors of the complement system have been described in the saliva of hematophagous arthropods that are involved in the protection of digestive tissues against complement system-mediated damage. In this study, we describe albicin, a novel inhibitor of the alternative pathway of complement from the salivary glands of the malaria vector, Anopheles albimanus The inhibitor was purified from salivary gland homogenates by reverse-phase HPLC and identified by mass spectrometry as a small (13.4-kDa) protein related to the gSG7 protein of Anopheles gambiae and Anopheles stephensi Recombinant albicin was produced in Escherichia coli and found to potently inhibit lysis of rabbit erythrocytes in assays of the alternative pathway while having no inhibitory effect on the classical or lectin pathways. Albicin also inhibited the deposition of complement components on agarose-coated plates, although it could not remove previously bound components. Antisera produced against recombinant albicin recognized both the native and recombinant inhibitors and also blocked their activities in in vitro assays. Using surface plasmon resonance and enzymatic assays, we found that albicin binds and stabilizes the C3-convertase complex (C3bBb) formed on a properdin surface and inhibits the convertase activity of a reconstituted C3bBb complex in solution. The data indicate that albicin specifically recognizes the activated form of the complex, allowing more efficient inhibition by an inhibitor whose quantity is limited. PMID:27307559

  8. Structure of Complement C3(H2O) Revealed By Quantitative Cross-Linking/Mass Spectrometry And Modeling. (United States)

    Chen, Zhuo A; Pellarin, Riccardo; Fischer, Lutz; Sali, Andrej; Nilges, Michael; Barlow, Paul N; Rappsilber, Juri


    The slow but spontaneous and ubiquitous formation of C3(H2O), the hydrolytic and conformationally rearranged product of C3, initiates antibody-independent activation of the complement system that is a key first line of antimicrobial defense. The structure of C3(H2O) has not been determined. Here we subjected C3(H2O) to quantitative cross-linking/mass spectrometry (QCLMS). This revealed details of the structural differences and similarities between C3(H2O) and C3, as well as between C3(H2O) and its pivotal proteolytic cleavage product, C3b, which shares functionally similarity with C3(H2O). Considered in combination with the crystal structures of C3 and C3b, the QCMLS data suggest that C3(H2O) generation is accompanied by the migration of the thioester-containing domain of C3 from one end of the molecule to the other. This creates a stable C3b-like platform able to bind the zymogen, factor B, or the regulator, factor H. Integration of available crystallographic and QCLMS data allowed the determination of a 3D model of the C3(H2O) domain architecture. The unique arrangement of domains thus observed in C3(H2O), which retains the anaphylatoxin domain (that is excised when C3 is enzymatically activated to C3b), can be used to rationalize observed differences between C3(H2O) and C3b in terms of complement activation and regulation. PMID:27250206

  9. Allosterism in human complement component 5a ((h)C5a): a damper of C5a receptor (C5aR) signaling. (United States)

    Rana, Soumendra; Sahoo, Amita Rani; Majhi, Bharat Kumar


    The phenomena of allosterism continues to advance the field of drug discovery, by illuminating gainful insights for many key processes, related to the structure-function relationships in proteins and enzymes, including the transmembrane G-protein coupled receptors (GPCRs), both in normal as well as in the disease states. However, allosterism is completely unexplored in the native protein ligands, especially when a small covalent change significantly modulates the pharmacology of the protein ligands toward the signaling axes of the GPCRs. One such example is the human C5a ((h)C5a), the potent cationic anaphylatoxin that engages C5aR and C5L2 to elicit numerous immunological and non-immunological responses in humans. From the recently available structure-function data, it is clear that unlike the mouse C5a ((m)C5a), the (h)C5a displays conformational heterogeneity. However, the molecular basis of such conformational heterogeneity, otherwise allosterism in (h)C5a and its precise contribution toward the overall C5aR signaling is not known. This study attempts to decipher the functional role of allosterism in (h)C5a, by exploring the inherent conformational dynamics in (m)C5a, (h)C5a and in its point mutants, including the proteolytic mutant des-Arg(74)-(h)C5a. Prima facie, the comparative molecular dynamics study, over total 500 ns, identifies Arg(74)-Tyr(23) and Arg(37)-Phe(51) "cation-π" pairs as the molecular "allosteric switches" on (h)C5a that potentially functions as a damper of C5aR signaling. PMID:26212097

  10. 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

  11. The complement receptor C5aR1 contributes to renal damage but protects the heart in angiotensin II-induced hypertension. (United States)

    Weiss, Sebastian; Rosendahl, Alva; Czesla, Daniel; Meyer-Schwesinger, Catherine; Stahl, Rolf A K; Ehmke, Heimo; Kurts, Christian; Zipfel, Peter F; Köhl, Jörg; Wenzel, Ulrich O


    Adaptive and innate immune responses contribute to hypertension and hypertensive end-organ damage. Here, we determined the role of anaphylatoxin C5a, a major inflammatory effector of the innate immune system that is generated in response to complement activation, in hypertensive end-organ damage. For this purpose, we assessed the phenotype of C5a receptor 1 (C5aR1)-deficient mice in ANG II-induced renal and cardiac injury. Expression of C5aR1 on infiltrating and resident renal as well as cardiac cells was determined using a green fluorescent protein (GFP)-C5aR1 reporter knockin mouse. Flow cytometric analysis of leukocytes isolated from the kidney of GFP-C5aR1 reporter mice showed that 28% of CD45-positive cells expressed C5aR1. Dendritic cells were identified as the major C5aR1-expressing population (88.5%) followed by macrophages and neutrophils. Using confocal microscopy, we detected C5aR1 in the kidney mainly on infiltrating cells. In the heart, only infiltrating cells stained C5aR1 positive. To evaluate the role of C5aR1 deficiency in hypertensive injury, an aggravated model of hypertension was used. Unilateral nephrectomy was performed followed by infusion of ANG II (1.5 ng·g(-1)·min(-1)) and salt in wild-type (n = 34) and C5aR1-deficient mice (n = 32). C5aR1-deficient mice exhibited less renal injury, as evidenced by significantly reduced albuminuria. In contrast, cardiac injury was accelerated with significantly increased cardiac fibrosis and heart weight in C5aR1-deficient mice after ANG II infusion. No effect was found on blood pressure. In summary, the C5a:C5aR1 axis drives end-organ damage in the kidney but protects from the development of cardiac fibrosis and hypertrophy in experimental ANG II-induced hypertension. PMID:27053686

  12. A scabies mite serpin interferes with complement-mediated neutrophil functions and promotes staphylococcal growth.

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    Pearl M Swe


    Full Text Available BACKGROUND: Scabies is a contagious skin disease caused by the parasitic mite Sarcoptes scabiei. The disease is highly prevalent worldwide and known to predispose to secondary bacterial infections, in particular by Streptococcus pyogenes and Staphylococcus aureus. Reports of scabies patients co-infected with methicillin resistant S. aureus (MRSA pose a major concern for serious down-stream complications. We previously reported that a range of complement inhibitors secreted by the mites promoted the growth of S. pyogenes. Here, we show that a recently characterized mite serine protease inhibitor (SMSB4 inhibits the complement-mediated blood killing of S. aureus. METHODOLOGY/PRINCIPAL FINDINGS: Blood killing of S. aureus was measured in whole blood bactericidal assays, counting viable bacteria recovered after treatment in fresh blood containing active complement and phagocytes, treated with recombinant SMSB4. SMSB4 inhibited the blood killing of various strains of S. aureus including methicillin-resistant and methicillin-sensitive isolates. Staphylococcal growth was promoted in a dose-dependent manner. We investigated the effect of SMSB4 on the complement-mediated neutrophil functions, namely phagocytosis, opsonization and anaphylatoxin release, by flow cytometry and in enzyme linked immuno sorbent assays (ELISA. SMSB4 reduced phagocytosis of S. aureus by neutrophils. It inhibited the deposition of C3b, C4b and properdin on the bacteria surface, but did not affect the depositions of C1q and MBL. SMSB4 also inhibited C5 cleavage as indicated by a reduced C5b-9 deposition. CONCLUSIONS/SIGNIFICANCE: We postulate that SMSB4 interferes with the activation of all three complement pathways by reducing the amount of C3 convertase formed. We conclude that SMSB4 interferes with the complement-dependent killing function of neutrophils, thereby reducing opsonization, phagocytosis and further recruitment of neutrophils to the site of infection. As a

  13. Cloning, expression and localization of DacaCSP2 and DacaCSP3 during different reproductive stages in Daphnia carinata. (United States)

    Li, Haixia; Yang, Yang; Xu, Guorong; Wu, Donglei; Lv, Weiwei; Jiang, Qicheng; Zhao, Yunlong


    Daphnia carinata are unique freshwater crustaceans that undergo both sexual and asexual reproduction, depending on environmental factors. While the molecular mechanism behind the reproductive transformation has been unknown, chemosensory proteins (CSPs) may be involved. We have cloned the cDNA sequences of two CSP genes from D. carinata using primers based on homologous sequences and rapid amplification of cDNA ends (RACE). The full-length cDNA of DacaCSP2 (GenBank accession no: KM624608) was 632bp, with an ORF (open reading frame) of 330bp encoding a 12.02kDa protein; and the full-length cDNA of DacaCSP3 (GenBank accession no: KM624609) was 935bp, with an ORF of 342bp encoding a 12.78kDa protein. Both CSPs encoded an N-terminal signal peptide, four conserved cysteines, an OS-D superfamily domain, a 2Fe-2S ferredoxin domain, an anaphylatoxin domain and an EGF-like domain. DaCaCSP2 and DaCaCSP3 proteins were most closely related to CSPs from Daphnia pulex and were more distantly related to CSPs from other insects. Using quantitative PCR, we found expression levels of DaCaCSP2 and DaCaCSP3 mRNA were highest in sexual females, followed by parthenogenetic females, and lowest in males. The expression levels of DaCaCSP2 and DaCaCSP3 mRNA also increased at lower temperatures, which suggested they could respond to environmental cues. Whole mount in situ hybridization (ISH) showed that DaCaCSP2 and DaCaCSP3 were expressed mainly in the ovaries, summer eggs, thoracic limbs, rectum and second antennae in sexual females; while they were expressed mainly in the ovaries, thoracic limbs, rectum and second antennae in parthenogenetic females. Together, these results suggest that DacaCSP2 and DacaCSP3 may respond to environmental cues and control the reproductive switch from sexual to asexual reproduction in D. carinata. PMID:26828612

  14. Distinct associations of complement C3a and its precursor C3 with atherosclerosis and cardiovascular disease. The CODAM study. (United States)

    Hertle, Elisabeth; van Greevenbroek, Marleen M; Arts, Ilja C; van der Kallen, Carla J; Geijselaers, Stefan L; Feskens, Edith J; Jansen, Eugene H; Schalkwijk, Casper G; Stehouwer, Coen D


    Complement C3 is a novel risk factor for cardiovascular disease (CVD), but the underlying mechanism is currently unknown. We determined the associations of the anaphylatoxin C3a, the activation product of C3, and of C3 itself with estimates of atherosclerosis and CVD. We studied associations of C3a and C3 with carotid intima-media thickness (cIMT), ankle-arm blood pressure index (AAIx) and CVD in cross-sectional analyses among 545 participants of the Cohort on Diabetes and Atherosclerosis Maastricht (CODAM) study (62% men, 59.4 ± 6.9 years) and examined effect modification by smoking. We conducted linear and logistic regression analyses with adjustments for age, sex, glucose metabolism status, lipids, adiposity, renal function, blood pressure, pack-years smoked, physical activity, use of medication and investigated mediation by inflammation. C3a was independently associated with cIMT (β=0.032 mm, [95% confidence interval: 0.004; 0.060]) and AAIx (β=-0.022, [-0.043; -0.001]), but C3 was not. Effect modification by smoking was only observed for CVD (P(smoking*C3a)=0.008, P(smoking*C3)=0.018), therefore these associations were stratified for smoking behaviour. Both C3a (odds ratio [OR] =2.96, [1.15; 7.62]) and C3 (OR =1.98, [1.21; 3.22]) were independently associated with CVD in heavy smokers. The association of C3 with CVD was independent of C3a. Low-grade inflammation did partially explain the association of C3a with AAIx, but not the other observed associations. This suggests that C3a and C3 have distinct roles in pathways leading to CVD. C3a may promote atherosclerosis and additionally advance CVD in heavy smokers. Conversely, C3 may be associated with CVD in heavy smokers via pathways other than atherosclerosis. PMID:24500020

  15. Quantitative proteomic analysis on the serum of patients with medicamentose-like dermatitis induced by occupational trichloroethylene exposure%职业性三氯乙烯药疹样皮炎患者血清蛋白质差异表达分析

    Institute of Scientific and Technical Information of China (English)

    黄振烈; 越飞; 黄汉林; 杨杏芬; 夏丽华; 陈慈珊; 邱新香; 黄建勋; 李来玉


    Objective To compare the proteome of the serum of patients with medicamentose-like dermatitis due to occupational trichloroethylene exposure(OMDTE) in acute and recovery stages. Methods After the samples were collected and pretreated, the expression of protein in serum was analyzed by 2-dimensional electrophoresis (2-DE) and differentially expressed protein spots were identified by matrix assisted laser desorption ionization-time of flight mass spectrometry ( MALDI-TOF-TOF/ MS). Results 31 proteins with altered modifications were separated and identified by 2-DE combined with MALDI-TOF-TOF/ MS. Compared with the serum proteome in the recovery stage, proteins showed up-regulated expression in acute stage included S100 cal-cium-binding protein A8, calprotectin, amyloid related serum protein SAA, leucine aminopeptidase, plasma glutathione peroxidase, etc. However, retinol binding protein, acetyl-CoA carboxylase and carboxypeptidase N were down-regulated. The function of these proteins involved in inflammatory responses, oxidative stress, retinol metabolism, fatty acid metabolism and regulation of kinins and anaphylatoxins. Conclusion The identified proteins provided target molecules for the further study on mechanisms of OMDTE and can be used as potential biomarkers for the disease.%目的 比较职业性三氯乙烯药疹样皮炎(OMDTE)患者发病急性期与治愈后的血清蛋白质表达谱.方法 患者血清经前处理后,双向凝胶电泳分离蛋白质,软件分析凝胶图像,基质辅助激光解吸电离飞行时间串联质谱鉴定差异表达蛋白斑点.结果 与治愈后的血清蛋白质表达谱比较,在发病急性期发现41个明显差异表达的蛋白斑点,鉴定出31个蛋白.上调的蛋白有S100钙结合蛋白A8、钙网蛋白、血清淀粉样蛋白A、亮氨酸氨基肽酶、谷胱甘肤过氧化物酶等;下调的蛋白有视黄醇结合蛋白、乙酰辅酶A羧化酶、羧肽酶N等;涉及的功能通路包括炎症反应、氧