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Sample records for complement component c3

  1. Complement component 3 (C3)

    MedlinePlus

    C3 and C4 are the most commonly measured complement components. A complement test may be used to monitor people with an ... normal levels of the complement proteins C3 and C4 . Complement activity varies throughout the body. For example, ...

  2. Engineering of human complement component C3 for catalytic inhibition of complement.

    PubMed

    Kölln, Johanna; Bredehorst, Reinhard; Spillner, Edzard

    2005-04-15

    As a novel therapeutic approach in complement-mediated pathologies, we recently developed a human C3 derivative capable of obliterating functional complement by a catalytic, non-inhibitory mechanism. In this derivative, the C-terminal region of hC3 was substituted by a 275 amino acid sequence derived from the corresponding sequence of cobra venom factor (CVF), a complement-activating C3b homologue from snake venom. In this study, we replaced shorter C-terminal sequences of hC3 by corresponding CVF sequences to further reduce potential immunogenicity and to identify domains essential for the formation of functionally stable C3 convertases. In one of these derivatives that is still capable of obliterating functional complement in vitro, the non-human portion could be reduced to a small domain located in the C-terminus of different complement proteins. This conserved NTR/C345C motif is known to be involved in assembly of different convertases of the complement system. These results suggest a major role of the C345C domain in the regulation of the half-life of the C3 convertase. Moreover, its overall identity of 96% to human C3 renders this derivative a promising candidate for therapeutic intervention in complement-mediated pathologies. PMID:15790508

  3. Human genes for three complement components that regulate the activation of C3 are tightly linked.

    PubMed

    Rodriguez de Cordoba, S; Lublin, D M; Rubinstein, P; Atkinson, J P

    1985-05-01

    A new cluster of complement component genes, including C4BP, C3bR, and FH, is described. Family segregation data indicate that FH is linked to the genes for C4-bp and C4bR, previously reported to be linked and to maintain linkage disequilibrium. This cluster is not linked to the major histocompatibility complex, which contains the genes for the complement components, C4, C2, and factor B, or to the C3 locus. These data further suggest that the organization of genes for functionally related proteins in clusters may be a rule for the complement system. PMID:3157763

  4. Third component of complement (C3): structural properties in relation to functions.

    PubMed Central

    Bokisch, V A; Dierich, M P; Mūller-Eberhard, H J

    1975-01-01

    The third component of complement (C3) fulfills a pivotal role in the functions of the complement system. We have investigated the topological relationships among its polypeptide chains, physiologic fragments, enzyme attack regions, and functional sites. C3 consists of two chains (alpha and beta) which are linked by disulfide bonds and noncovalent forces and which have molecular weights of, respectively, 120,000 and 75,000. C3 is activated by action of C3 convertase on the alpha-chain. With hydrolysis of one polypeptide bonds, C3a, the 9000 dalton activation peptide is dislocated from the NH2-terminal portion of the alpha-chain. A previously concealed binding region is thereby transiently revealed in the C3b-fragment (181,000 dalton) which displays affinity for apparently nonspecific acceptors present on biological membranes. Binding of nascent C3b membranes occurs through the C3d portion of the fragment because subsequent action of the C3b-inactivator or trypsin on bound C3b causes release of C3c, but not of C3d. Bound C3b and C3d possess stable sites that are capable of binding to specific receptors present on a limited variety of cells. We propose that all known physiologically occurring fragments of C3 arise by enzymatic cleavage of the alpha-chain: C3a, C3b, C3c, and C3d. Whereas C3a (alpha1) and C3e (alpha2) consist of a single chain and C3b consists of two chains (alpha' and beta), C3c is composed of the entire beta-chain and multiple fragments of the alpha-chain, each of which is linked by disulfide bonds to the beta-chain. Images PMID:1056006

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

    SciTech Connect

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

    1987-08-01

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

  6. Modulation of human B cell immunoglobulin secretion by the C3b component of complement.

    PubMed

    Tsokos, G C; Berger, M; Balow, J E

    1984-02-01

    The human C3b component of complement was found to inhibit the differentiation of human B lymphocytes into immunoglobulin-secreting cells in vitro. Pokeweed mitogen (PWM)-induced plaque-forming cell (PFC) responses were inhibited by C3-coated zymosan particles and by purified human C3b. C3b inhibited the PWM-driven responses in a dose-dependent fashion, and it was necessary for C3b to be present in the early phases of the cultures. C3b acted directly on B cells rather than on helper T cells because it inhibited the PFC responses of MNC depleted of T cells and subsequently stimulated with a T cell-independent Epstein Barr virus mitogen. Furthermore, C3b failed to stimulate the generation of suppressor lymphocytes and/or monocytes that might have been responsible for the inhibition of B cell responses. Our results indicate that C3b or its fragments exert negative modulatory effects on human B lymphocyte responses. PMID:6228593

  7. Therapeutic control of complement activation at the level of the central component C3.

    PubMed

    Ricklin, Daniel; Lambris, John D

    2016-06-01

    The increasing recognition of the complement system's association with diseases of the inflammatory spectrum and with biomaterial and transplant-related complications has generated growing interest in the therapeutic modulation of this innate immune cascade. As a central functional hub that largely drives the activation, amplification, and effector generation of the complement response, the plasma protein C3 has long been recognized as an attractive target. While pharmacological modulation of C3 activation may offer a powerful opportunity to interfere with or even prevent complement-driven pathologies, the development of C3 inhibitors has often been accompanied by concerns regarding the safety and feasibility of this approach. Although no C3-targeted inhibitors have thus far been approved for clinical use, several promising concepts and candidates have emerged in recent years. At the same time, experiences from preclinical development and clinical trials are slowly providing a more detailed picture of therapeutic complement inhibition at the level of C3. This review highlights the current therapeutic strategies to control C3 activation and discusses the possibilities and challenges on the road to bringing C3-targeted therapeutics to the clinic. PMID:26101137

  8. Contribution of complement component C3 and complement receptor type 3 to carbohydrate-dependent uptake of oligomannose-coated liposomes by peritoneal macrophages.

    PubMed

    Abe, Yu; Kuroda, Yasuhiro; Kuboki, Noritaka; Matsushita, Misao; Yokoyama, Naoaki; Kojima, Naoya

    2008-11-01

    Peritoneal macrophages (PEMs) preferentially and rapidly take up oligomannose-coated liposomes (OMLs) and subsequently mature to induce a Th-1 immune response following administration of OMLs into the peritoneal cavity. Here, we examine the contributions of complement component C3 and complement receptor type 3 (CR3) to carbohydrate-dependent uptake of OMLs by PEMs. Effective uptake of OMLs into PEMs in vitro was observed only in the presence of peritoneal fluid (PF), and OMLs incubated with PF were incorporated by PEMs in vitro in the absence of PF. These phenomena were inhibited by methyl-alpha-mannoside, N-acetylglucosamine or EDTA, but not by galactose. Pull-down analysis followed by peptide mass fingerprinting of PF-treated OMLs indicated that the OMLs were opsonized with complement fragment iC3b. In vivo uptake of OMLs by PEMs was inhibited by intraperitoneal injection of an antibody against CR3, a receptor for iC3b, and OML uptake by PEMs in the peritoneal cavity was not observed in C3-deficient mice. Thus, our results indicate that OMLs are opsonized with iC3b in a mannose-dependent manner in the peritoneal cavity and then incorporated into PEMs via CR3. PMID:18694897

  9. The structure of C2b, a fragment of complement component C2 produced during C3 convertase formation

    SciTech Connect

    Krishnan, Vengadesan; Xu, Yuanyuan; Macon, Kevin; Volanakis, John E.; Narayana, Sthanam V. L.

    2009-03-01

    The crystal structure of C2b has been determined at 1.8 Å resolution, which reveals the arrangement of its three complement control protein (CCP) modules. A model for complement component C2 is presented and its conformational changes during the C3-convertase formation are also discussed. The second component of complement (C2) is a multi-domain serine protease that provides catalytic activity for the C3 and C5 convertases of the classical and lectin pathways of human complement. The formation of these convertases requires the Mg{sup 2+}-dependent binding of C2 to C4b and the subsequent cleavage of C2 by C1s or MASP2, respectively. The crystal structure of full-length C2 is not yet available, although the structure of its C-terminal catalytic segment C2a has been determined. The crystal structure of the N-terminal segment C2b of C2 determined to 1.8 Å resolution presented here reveals the arrangement of its three CCP domains. The domains are arranged differently compared with most other CCP-domain assemblies, but their arrangement is similar to that found in the Ba part of the full-length factor B structure. The crystal structures of C2a, C2b and full-length factor B are used to generate a model for C2 and a discussion of the domain association and possible interactions with C4b during formation of the C4b–C2 complex is presented. The results of this study also suggest that upon cleavage by C1s, C2a domains undergo conformational rotation while bound to C4b and the released C2b domains may remain folded together similar to as observed in the intact protein.

  10. Complement Component C3 and Butyrylcholinesterase Activity Are Associated with Neurodegeneration and Clinical Disability in Multiple Sclerosis

    PubMed Central

    Al Nimer, Faiez; Vijayaraghavan, Swetha; Sandholm, Kerstin; Khademi, Mohsen; Olsson, Tomas; Nilsson, Bo; Ekdahl, Kristina Nilsson; Darreh-Shori, Taher; Piehl, Fredrik

    2015-01-01

    Dysregulation of the complement system is evident in many CNS diseases but mechanisms regulating complement activation in the CNS remain unclear. In a recent large rat genome-wide expression profiling and linkage analysis we found co-regulation of complement C3 immediately downstream of butyrylcholinesterase (BuChE), an enzyme hydrolyzing acetylcholine (ACh), a classical neurotransmitter with immunoregulatory effects. We here determined levels of neurofilament-light (NFL), a marker for ongoing nerve injury, C3 and activity of the two main ACh hydrolyzing enzymes, acetylcholinesterase (AChE) and BuChE, in cerebrospinal fluid (CSF) from patients with MS (n = 48) and non-inflammatory controls (n = 18). C3 levels were elevated in MS patients compared to controls and correlated both to disability and NFL. C3 levels were not induced by relapses, but were increased in patients with ≥9 cerebral lesions on magnetic resonance imaging and in patients with progressive disease. BuChE activity did not differ at the group level, but was correlated to both C3 and NFL levels in individual samples. In conclusion, we show that CSF C3 correlates both to a marker for ongoing nerve injury and degree of disease disability. Moreover, our results also suggest a potential link between intrathecal cholinergic activity and complement activation. These results motivate further efforts directed at elucidating the regulation and effector functions of the complement system in MS, and its relation to cholinergic tone. PMID:25835709

  11. Rare loss-of-function mutation in complement component C3 provides insight into molecular and pathophysiological determinants of complement activity

    PubMed Central

    Sfyroera, Georgia; Ricklin, Daniel; Reis, Edimara S.; Chen, Hui; Wu, Emilia L.; Kaznessis, Yiannis N.; Ekdahl, Kristina N.; Nilsson, Bo; Lambris, John D.

    2015-01-01

    The plasma protein C3 is a central element in the activation and effector functions of the complement system. A hereditary dysfunction of C3 that prevents complement activation via the alternative pathway (AP) was described previously in a Swedish family, but its genetic cause and molecular consequences have remained elusive. Here we provide these missing links by pinpointing the dysfunction to a point mutation in the β-chain of C3 (c.1180T>C; p.Met373Thr). In the patient’s plasma, AP activity was completely abolished and could only be reconstituted with the addition of normal C3. The M373T mutation was localized to the macroglobulin domain 4 (MG4) of C3, which contains a binding site for the complement inhibitor compstatin and is considered critical for the interaction of C3 with the AP C3 convertase. Structural analyses suggested that the mutation disturbs the integrity of MG4 and induces conformational changes that propagate into adjacent regions. Indeed, C3 M373T showed an altered binding pattern for compstatin and surface-bound C3b, and the presence of Thr-373 in either the C3 substrate or convertase-affiliated C3b impaired C3 activation and opsonization. In contrast to known gain-of-function mutations in C3, patients affected by this loss-of-function mutation did not develop familial disease, but rather showed diverse and mostly episodic symptoms. Our study therefore reveals the molecular mechanism of a relevant loss-of-function mutation in C3 and provides insight into the function of the C3 convertase, the differential involvement of C3 activity in clinical conditions, and some potential implications of therapeutic complement inhibition. PMID:25712219

  12. Complement component C3b and immunoglobulin Fc receptors on neutrophils from calves with leukocyte adhesion deficiency.

    PubMed

    Worku, M; Paape, M J; Di Carlo, A; Kehrli, M E; Marquardt, W W

    1995-04-01

    Receptors for opsonins, such as complement component C3b (CR1) and immunoglobulins, Fc receptors, interact with adhesion glycoproteins in mediating immune functions. Defects in expression of the adhesion glycoproteins CD11/CD18 results in severely hampered in vitro and in vivo adherence-related functions of leukocytes. Little is known regarding the effect of leukocyte adhesion deficiency (LAD) on ligand binding and receptor expression. We investigated the binding and expression of CR1 and Fc receptors by bovine neutrophils isolated from dairy calves suffering from LAD, compared with clinically normal (hereafter referred to as normal) age-matched calves. Neutrophils were also assayed for endogenously bound IgG and IgM and for exogenous binding of C3b, IgG1, IgG2, IgM, and aggregated IgG (aIgG), using flow cytometry. Luminol-enhanced chemiluminescence (CL) production in response to IgG2 opsonized zymosan was studied, and specific inhibition of CL was used to determine the specificity of IgG2 binding. Activation of protein kinase C with phorbol myristate acetate was used to determine the effect of cellular activation on expression of CR1. A greater percentage of neutrophils from normal calves bound C3b than did neutrophils from LAD-affected calves. Receptor expression was similar. Activation with phorbol myristate acetate resulted in increased expression of CR1 on neutrophils from normal and LAD-affected calves, but expression was almost twofold greater on neutrophils from normal calves. There was no difference between LAD-affected and normal calves in percentage of neutrophils that bound endogenous IgG and IgM. A greater percentage of neutrophils from normal calves bound exogenous IgM than did neutrophils from LAD-affected calves.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7785817

  13. Elevated IgG and decreased complement component C3 and factor B in B-thalassaemia major.

    PubMed

    Sinniah, D; Yadav, M

    1981-07-01

    Serum immunoglobulins, complements C3 and C4 and factor B were assayed in the sera of children with B-thalassaemia major, siblings and matched controls in an attempt to resolve the controversy surrounding the conflicting results reported in the literature. Significantly elevated IgG and decreased C3 and factor B levels were observed in thalassaemic patients who also had a high incidence of HBS hepatitis and other infections. The controversial results probably reflect differences in the incidence of infection, and the presence of circulating immune complexes due to blood transfusions, in the various communities. The alterations in immunoglobulin and complement levels represent a secondary rather than a primary immune disorder. PMID:6914868

  14. Characterization of the gene encoding component C3 of the complement system from the spider Loxosceles laeta venom glands: Phylogenetic implications.

    PubMed

    Myamoto, D T; Pidde-Queiroz, G; Pedroso, A; Gonçalves-de-Andrade, R M; van den Berg, C W; Tambourgi, D V

    2016-09-01

    A transcriptome analysis of the venom glands of the spider Loxosceles laeta, performed by our group, in a previous study (Fernandes-Pedrosa et al., 2008), revealed a transcript with a sequence similar to the human complement component C3. Here we present the analysis of this transcript. cDNA fragments encoding the C3 homologue (Lox-C3) were amplified from total RNA isolated from the venom glands of L. laeta by RACE-PCR. Lox-C3 is a 5178 bps cDNA sequence encoding a 190kDa protein, with a domain configuration similar to human C3. Multiple alignments of C3-like proteins revealed two processing sites, suggesting that Lox-C3 is composed of three chains. Furthermore, the amino acids consensus sequences for the thioester was found, in addition to putative sequences responsible for FB binding. The phylogenetic analysis showed that Lox-C3 belongs to the same group as two C3 isoforms from the spider Hasarius adansoni (Family Salcitidae), showing 53% homology with these. This is the first characterization of a Loxosceles cDNA sequence encoding a human C3 homologue, and this finding, together with our previous finding of the expression of a FB-like molecule, suggests that this spider species also has a complement system. This work will help to improve our understanding of the innate immune system in these spiders and the ancestral structure of C3. PMID:27259372

  15. Complement (C3), nutrition, and infection*

    PubMed Central

    Kielmann, A. A.; Curcio, L. M.

    1979-01-01

    Complement (C3) was determined and related to various parameters of nutritional status and past infectious disease experience in a group of 53 rural preschool children in North India. Mean complement level was 25% lower than in an age-matched European reference population. Low complement (C3) levels were associated mainly with children who were both stunted and wasted, as well as with those who had experienced frequent purulent skin infections in the past. PMID:311708

  16. Iron-induced Local Complement Component 3 (C3) Up-regulation via Non-canonical Transforming Growth Factor (TGF)-β Signaling in the Retinal Pigment Epithelium*

    PubMed Central

    Li, Yafeng; Song, Delu; Song, Ying; Zhao, Liangliang; Wolkow, Natalie; Tobias, John W.; Song, Wenchao; Dunaief, Joshua L.

    2015-01-01

    Dysregulation of iron homeostasis may be a pathogenic factor in age-related macular degeneration (AMD). Meanwhile, the formation of complement-containing deposits under the retinal pigment epithelial (RPE) cell layer is a pathognomonic feature of AMD. In this study, we investigated the molecular mechanisms by which complement component 3 (C3), a central protein in the complement cascade, is up-regulated by iron in RPE cells. Modulation of TGF-β signaling, involving ERK1/2, SMAD3, and CCAAT/enhancer-binding protein-δ, is responsible for iron-induced C3 expression. The differential effects of spatially distinct SMAD3 phosphorylation sites at the linker region and at the C terminus determined the up-regulation of C3. Pharmacologic inhibition of either ERK1/2 or SMAD3 phosphorylation decreased iron-induced C3 expression levels. Knockdown of SMAD3 blocked the iron-induced up-regulation and nuclear accumulation of CCAAT/enhancer-binding protein-δ, a transcription factor that has been shown previously to bind the basic leucine zipper 1 domain in the C3 promoter. We show herein that mutation of this domain reduced iron-induced C3 promoter activity. In vivo studies support our in vitro finding of iron-induced C3 up-regulation. Mice with a mosaic pattern of RPE-specific iron overload demonstrated co-localization of iron-induced ferritin and C3d deposits. Humans with aceruloplasminemia causing RPE iron overload had increased RPE C3d deposition. The molecular events in the iron-C3 pathway represent therapeutic targets for AMD or other diseases exacerbated by iron-induced local complement dysregulation. PMID:25802332

  17. Iron-induced Local Complement Component 3 (C3) Up-regulation via Non-canonical Transforming Growth Factor (TGF)-β Signaling in the Retinal Pigment Epithelium.

    PubMed

    Li, Yafeng; Song, Delu; Song, Ying; Zhao, Liangliang; Wolkow, Natalie; Tobias, John W; Song, Wenchao; Dunaief, Joshua L

    2015-05-01

    Dysregulation of iron homeostasis may be a pathogenic factor in age-related macular degeneration (AMD). Meanwhile, the formation of complement-containing deposits under the retinal pigment epithelial (RPE) cell layer is a pathognomonic feature of AMD. In this study, we investigated the molecular mechanisms by which complement component 3 (C3), a central protein in the complement cascade, is up-regulated by iron in RPE cells. Modulation of TGF-β signaling, involving ERK1/2, SMAD3, and CCAAT/enhancer-binding protein-δ, is responsible for iron-induced C3 expression. The differential effects of spatially distinct SMAD3 phosphorylation sites at the linker region and at the C terminus determined the up-regulation of C3. Pharmacologic inhibition of either ERK1/2 or SMAD3 phosphorylation decreased iron-induced C3 expression levels. Knockdown of SMAD3 blocked the iron-induced up-regulation and nuclear accumulation of CCAAT/enhancer-binding protein-δ, a transcription factor that has been shown previously to bind the basic leucine zipper 1 domain in the C3 promoter. We show herein that mutation of this domain reduced iron-induced C3 promoter activity. In vivo studies support our in vitro finding of iron-induced C3 up-regulation. Mice with a mosaic pattern of RPE-specific iron overload demonstrated co-localization of iron-induced ferritin and C3d deposits. Humans with aceruloplasminemia causing RPE iron overload had increased RPE C3d deposition. The molecular events in the iron-C3 pathway represent therapeutic targets for AMD or other diseases exacerbated by iron-induced local complement dysregulation. PMID:25802332

  18. Complement inhibition in C3 glomerulopathy.

    PubMed

    Nester, Carla M; Smith, Richard J H

    2016-06-01

    C3 glomerulopathy (C3G) describes a spectrum of glomerular diseases defined by shared renal biopsy pathology: a predominance of C3 deposition on immunofluorescence with electron microscopy permitting disease sub-classification. Complement dysregulation underlies the observed pathology, a causal relationship that is supported by well described studies of genetic and acquired drivers of disease. In this article, we provide an overview of the features of C3G, including a discussion of disease definition and a review of the causal role of complement. We discuss molecular markers of disease and how biomarkers are informing our evolving understanding of underlying pathology. Research advances are laying the foundation for complement inhibition as a targeted approach to treatment of C3G. PMID:27402056

  19. Studies of group B streptococcal infection in mice deficient in complement component C3 or C4 demonstrate an essential role for complement in both innate and acquired immunity.

    PubMed Central

    Wessels, M R; Butko, P; Ma, M; Warren, H B; Lage, A L; Carroll, M C

    1995-01-01

    Group B streptococci (GBS) cause sepsis and meningitis in neonates and serious infections in adults with underlying chronic illnesses. Specific antibodies have been shown to be an important factor in protective immunity for neonates, but the role of serum complement is less well defined. To elucidate the function of the complement system in immunity to this pathogen, we have used the approach of gene targeting in embryonic stem cells to generate mice totally deficient in complement component C3. Comparison of C3-deficient mice with mice deficient in complement component C4 demonstrated that the 50% lethal dose for GBS infection was reduced by approximately 50-fold and 25-fold, respectively, compared to control mice. GBS were effectively killed in vitro by human blood leukocytes in the presence of specific antibody and C4-deficient serum but not C3-deficient serum. The defective opsonization by C3-deficient serum in vitro was corroborated by in vivo studies in which passive immunization of pregnant dams with specific antibodies conferred protection from GBS challenge to normal and C4-deficient pups but not C3-deficient pups. These results indicate that the alternative pathway is sufficient to mediate effective opsonophagocytosis and protective immunity to GBS in the presence of specific antibody. In contrast, the increased susceptibility to infection of non-immune mice deficient in either C3 or C4 implies that the classical pathway plays an essential role in host defense against GBS infection in the absence of specific immunity. Images Fig. 1 PMID:8524789

  20. Interleukin 6 Influences Germinal Center Development and Antibody Production via a Contribution of C3 Complement Component

    PubMed Central

    Kopf, Manfred; Herren, Suzanne; Wiles, Michael V.; Pepys, Mark B.; Kosco-Vilbois, Marie H.

    1998-01-01

    Mice rendered deficient for interleukin (IL) 6 by gene targeting were evaluated for their response to T cell–dependent antigens. Antigen-specific immunoglobulin (Ig)M levels were unaffected whereas all IgG isotypes showed varying degrees of alteration. Germinal center reactions occurred but remained physically smaller in comparison to those in the wild-type mice. This concurred with the observations that molecules involved in initial signaling events leading to germinal center formation were not altered (e.g., B7.2, CD40 and tumor necrosis factor R1). T cell priming was not impaired nor was a gross imbalance of T helper cell (Th) 1 versus Th2 cytokines observed. However, B7.1 molecules, absent from wild-type counterparts, were detected on germinal center B cells isolated from the deficient mice suggesting a modification of costimulatory signaling. A second alteration involved impaired de novo synthesis of C3 both in serum and germinal center cells from IL-6–deficient mice. Indeed, C3 provided an essential stimulatory signal for wild-type germinal center cells as both monoclonal antibodies that interrupted C3-CD21 interactions and sheep anti–mouse C3 antibodies caused a significant decrease in antigen-specific antibody production. In addition, germinal center cells isolated from C3–deficient mice produced a similar defect in isotype production. Low density cells with dendritic morphology were the local source of IL-6 and not the germinal center lymphocytes. Adding IL-6 in vitro to IL-6–deficient germinal center cells stimulated cell cycle progression and increased levels of antibody production. These findings reveal that the germinal center produces and uses molecules of the innate immune system, evolutionarily pirating them in order to optimally generate high affinity antibody responses. PMID:9815267

  1. Presence of immunoglobulins, C3 and cytolytic C5b-9 complement components on the surface of erythrocytes from patients with beta-thalassaemia/HbE disease.

    PubMed

    Malasit, P; Mahasorn, W; Mongkolsapaya, J; Singhathong, B; Fucharoen, S; Wasi, P; Bhakdi, S

    1997-03-01

    The occurrence of IgG, IgM, IgA, C3 and C5b-9 complement complexes on erythrocytes from 43 patients with beta-thalassaemia HbE disease was investigated. Indirect immunoradiometric assays using radioiodinated protein A were employed to quantify the individual components. We confirmed that circulating erythrocytes from thalassaemic patients contained elevated amounts of IgG, and small but significant amounts of C3. In addition, small but significant amounts of C5b-9 were detected. Levels of cell-bound IgG, C3 and C5b-9 were higher in splenectomized versus non-splenectomized patients. The presence of C5b-9 on circulating cells from five splenectomized patients was confirmed by an ELISA employing a monoclonal antibody specific for a C5b-9 neoantigen. When C5b-9 positive cells from two patients were solubilized with detergent and subjected to sucrose density gradient centrifugation, the terminal complexes sedimented as 25-40S macromolecules, thus behaving as membrane C5b-9 complexes. The presence of C8 and C9 in these high molecular weight fractions was directly demonstrated by Western blotting. These results constitute the first demonstration that circulating diseased erythrocytes may carry low numbers of potentially cytolytic C5b-9 complement complexes which may be partly responsible for the known ionic disturbances found in thalassaemic cells. Both bound C3 and C5b-9 could promote removal of diseased cells in the reticuloendothelial system. PMID:9054657

  2. Molecular basis of complement C3 deficiency in guinea pigs.

    PubMed Central

    Auerbach, H S; Burger, R; Dodds, A; Colten, H R

    1990-01-01

    In experiments to ascertain the biochemical basis of a genetically determined deficiency of the third component of complement (C3) in guinea pigs, we found that C3-deficient liver and peritoneal macrophages contain C3 messenger RNA of normal size (approximately 5 kb) and amounts, that this mRNA programs synthesis of pro-C3 in oocytes primed with liver RNA and in primary macrophage cultures. In each instance, heterodimeric native C3 protein was secreted with normal kinetics but the C3 protein product of the deficient cells failed to undergo autolytic cleavage and was unusually susceptible to proteolysis. These data and a selective failure of C3 in plasma of deficient animals to incorporate [14C]methylamine suggested either a mutation in primary structure of the C3 protein or a selective defect in co- or postsynthetic processing affecting the thiolester bridge, a structure important for C3 function. A mutation in the primary structure of C3 was ruled out by comparison of direct sequence analysis of C3 cDNA generated from two C3 deficient and two C3 sufficient guinea pig liver libraries. Three base pair differences, none resulting in derived amino acid sequence differences were identified. Finally, restriction fragment length polymorphisms were identified in the C3 gene that are independent of the deficiency phenotype. This marker of the C3 gene permits testing of these hypotheses using molecular biological and classical genetic methods. Images PMID:1973176

  3. Crystallization and X-ray diffraction analysis of the complement component-3 (C3) inhibitory domain of Efb from Staphylococcus aureus

    SciTech Connect

    Hammel, Michal; Ramyar, Kasra X.; Spencer, Charles T.; Geisbrecht, Brian V.

    2006-03-01

    The crystallization and results of multiwavelength anomalous diffraction studies of a recombinant C3-inhibitory fragment of Efb from S. aureus are reported. The extracellular fibrinogen-binding protein (Efb) of Staphylococcus aureus is a multifunctional virulence factor capable of potent inhibition of complement component-3 (C3) activity in addition to its previously described fibrinogen-binding properties. A truncated recombinant form of Efb (Efb-C) that binds C3 has been overexpressed and purified and has been crystallized using the hanging-drop vapor-diffusion technique. Crystals of native Efb-C grew in the tetragonal space group P4{sub 3} (unit-cell parameters a = b = 59.53, c = 46.63 Å) with two molecules in the asymmetric unit and diffracted well beyond 1.25 Å limiting Bragg spacing. To facilitate de novo phasing of the Efb-C crystals, two independent site-directed mutants were engineered in which either residue Ile112 or Val140 was replaced with methionine and crystals isomorphous to those of native Efb-C were reproduced using a seleno-l-methionine-labeled form of each mutant protein. Multiwavelength anomalous diffraction (MAD) data were collected on both mutants and analyzed for their phasing power toward solution and refinement of a high-resolution Efb-C crystal structure.

  4. Complement

    MedlinePlus

    ... the suspected disease are done first. C3 and C4 are the complement components measured most often. A ... normal levels of the complement proteins C3 and C4 . Complement activity varies throughout the body. For example, ...

  5. The role of complement in C3 glomerulopathy.

    PubMed

    Zipfel, Peter F; Skerka, Christine; Chen, Qian; Wiech, Thorsten; Goodship, Tim; Johnson, Sally; Fremeaux-Bacchi, Veronique; Nester, Clara; de Córdoba, Santiago Rodríguez; Noris, Marina; Pickering, Matthew; Smith, Richard

    2015-09-01

    C3 glomerulopathy describes a spectrum of disorders with glomerular pathology associated with C3 cleavage product deposition and with defective complement action and regulation (Fakhouri et al., 2010; Sethi et al., 2012b). Kidney biopsies from these patients show glomerular accumulation or deposition of C3 cleavage fragments, but no or minor deposition of immunoglobulins (Appel et al., 2005; D'Agati and Bomback, 2012; Servais et al., 2007; Sethi and Fervenza, 2011). At present the current situation asks for a better definition of the underlining disease mechanisms, for precise biomarkers, and for a treatment for this disease. The complement system is a self activating and propelling enzymatic cascade type system in which inactive, soluble plasma components are activated spontaneously and lead into an amplification loop (Zipfel and Skerka, 2009). Activation of the alternative pathway is spontaneous, occurs by default, and cascade progression leads to amplification by complement activators. The system however is self-controlled by multiple regulators and inhibitors, like Factor H that control cascade progression in fluid phase and on surfaces. The activated complement system generates a series of potent effector components and activation products, which damage foreign-, as well as modified self cells, recruit innate immune cells to the site of action, coordinate inflammation and the response of the adaptive immune system in form of B cells and T lymphocytes (Kohl, 2006; Medzhitov and Janeway, 2002; Ogden and Elkon, 2006; Carroll, 2004; Kemper and Atkinson, 2007; Morgan, 1999; Muller-Eberhard, 1986; Ricklin et al., 2010). Complement controls homeostasis and multiple reactions in the vertebrate organism including defense against microbial infections (Diaz-Guillen et al., 1999; Mastellos and Lambris, 2002; Nordahl et al., 2004; Ricklin et al., 2010). In consequence defective control of the spontaneous self amplifying cascade or regulation is associated with numerous

  6. Molecular Basis for Complement Recognition and Inhibition Determined by Crystallographic Studies of the Staphylococcal Complement Inhibitor (SCIN) Bound to C3c and C3b

    SciTech Connect

    Garcia, Brandon L.; Ramyar, Kasra X.; Tzekou, Apostolia; Ricklin, Daniel; McWhorter, William J.; Lambris, John D.; Geisbrecht, Brian V.

    2010-10-22

    The human complement system plays an essential role in innate and adaptive immunity by marking and eliminating microbial intruders. Activation of complement on foreign surfaces results in proteolytic cleavage of complement component 3 (C3) into the potent opsonin C3b, which triggers a variety of immune responses and participates in a self-amplification loop mediated by a multi-protein assembly known as the C3 convertase. The human pathogen Staphylococcus aureus has evolved a sophisticated and potent complement evasion strategy, which is predicated upon an arsenal of potent inhibitory proteins. One of these, the staphylococcal complement inhibitor (SCIN), acts at the level of the C3 convertase (C3bBb) and impairs downstream complement function by trapping the convertase in a stable but inactive state. Previously, we have shown that SCIN binds C3b directly and competitively inhibits binding of human factor H and, to a lesser degree, that of factor B to C3b. Here, we report the co-crystal structures of SCIN bound to C3b and C3c at 7.5 and 3.5 {angstrom} limiting resolution, respectively, and show that SCIN binds a critical functional area on C3b. Most significantly, the SCIN binding site sterically occludes the binding sites of both factor H and factor B. Our results give insight into SCIN binding to activated derivatives of C3, explain how SCIN can recognize C3b in the absence of other complement components, and provide a structural basis for the competitive C3b-binding properties of SCIN. In the future, this may suggest templates for the design of novel complement inhibitors based upon the SCIN structure.

  7. Intracellular sensing of complement C3 activates cell autonomous immunity

    PubMed Central

    Tam, Jerry C.H.; Bidgood, Susanna R.; McEwan, William A.; James, Leo C.

    2014-01-01

    Pathogens traverse multiple barriers during infection including cell membranes. Here we show that during this transition pathogens carry covalently attached complement C3 into the cell, triggering immediate signalling and effector responses. Sensing of C3 in the cytosol activates MAVS-dependent signalling cascades and induces proinflammatory cytokine secretion. C3 also flags viruses for rapid proteasomal degradation, thereby preventing their replication. This system can detect both viral and bacterial pathogens but is antagonized by enteroviruses, such as rhinovirus and poliovirus, which cleave C3 using their 3C protease. The antiviral Rupintrivir inhibits 3C protease and prevents C3 cleavage, rendering enteroviruses susceptible to intracellular complement sensing. Thus, complement C3 allows cells to detect and disable pathogens that have invaded the cytosol. PMID:25190799

  8. Intracellular sensing of complement C3 activates cell autonomous immunity.

    PubMed

    Tam, Jerry C H; Bidgood, Susanna R; McEwan, William A; James, Leo C

    2014-09-01

    Pathogens traverse multiple barriers during infection, including cell membranes. We found that during this transition, pathogens carried covalently attached complement C3 into the cell, triggering immediate signaling and effector responses. Sensing of C3 in the cytosol activated mitochondrial antiviral signaling (MAVS)-dependent signaling cascades and induced proinflammatory cytokine secretion. C3 also flagged viruses for rapid proteasomal degradation, preventing their replication. This system could detect both viral and bacterial pathogens but was antagonized by enteroviruses, such as rhinovirus and poliovirus, which cleave C3 using their 3C protease. The antiviral rupintrivir inhibited 3C protease and prevented C3 cleavage, rendering enteroviruses susceptible to intracellular complement sensing. Thus, complement C3 allows cells to detect and disable pathogens that have invaded the cytosol. PMID:25190799

  9. A Familial C3GN Secondary to Defective C3 Regulation by Complement Receptor 1 and Complement Factor H.

    PubMed

    Chauvet, Sophie; Roumenina, Lubka T; Bruneau, Sarah; Marinozzi, Maria Chiara; Rybkine, Tania; Schramm, Elizabeth C; Java, Anuja; Atkinson, John P; Aldigier, Jean Claude; Bridoux, Frank; Touchard, Guy; Fremeaux-Bacchi, Veronique

    2016-06-01

    C3 glomerulopathy is a recently described form of CKD. C3GN is a subtype of C3 glomerulopathy characterized by predominant C3 deposits in the glomeruli and is commonly the result of acquired or genetic abnormalities in the alternative pathway (AP) of the complement system. We identified and characterized the first mutation of the C3 gene (p. I734T) in two related individuals diagnosed with C3GN. Immunofluorescence and electron microscopy studies showed C3 deposits in the subendothelial space, associated with unusual deposits located near the complement receptor 1 (CR1)-expressing podocytes. In vitro, this C3 mutation exhibited decreased binding to CR1, resulting in less CR1-dependent cleavage of C3b by factor 1. Both patients had normal plasma C3 levels, and the mutant C3 interacted with factor B comparably to wild-type (WT) C3 to form a C3 convertase. Binding of mutant C3 to factor H was normal, but mutant C3 was less efficiently cleaved by factor I in the presence of factor H, leading to enhanced C3 fragment deposition on glomerular cells. In conclusion, our results reveal that a CR1 functional deficiency is a mechanism of intraglomerular AP dysregulation and could influence the localization of the glomerular C3 deposits. PMID:26471127

  10. A Revised Mechanism for the Activation of Complement C3 to C3b

    PubMed Central

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

    2015-01-01

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

  11. A complement receptor locus: genes encoding C3b/C4b receptor and C3d/Epstein-Barr virus receptor map to 1q32.

    PubMed

    Weis, J H; Morton, C C; Bruns, G A; Weis, J J; Klickstein, L B; Wong, W W; Fearon, D T

    1987-01-01

    The alternative or classical pathways for complement system component C3 may be triggered by microorganisms and antigen-antibody complexes. In particular, an activated fragment of C3, C3b, covalently attaches to microorganisms or antigen-antibody complexes, which in turn bind to the C3b receptor, also known as complement receptor 1. The genes encoding the proteins that constitute the C3-activating enzymes have been cloned and mapped to a "complement activation" locus in the major histocompatibility complex, and we demonstrate in this study such a locus on the long arm of chromosome 1 at band 1q32. PMID:3782802

  12. C3 glomerulopathy: A new complement-based entity.

    PubMed

    de Lorenzo, A; Tallón, S; Hernández-Sevillano, B; de Arriba, G

    2014-01-01

    C3 glomerulopathy is a new, recently described entity that has changed the perspective, treatment and classification of a number of glomerular diseases. It encompasses 2 similar but clearly differentiated pathologies -the dense-deposit disease and C3 glomerulonephritis itself. The alternative complement pathway plays a fundamental role in its pathogenesis and, specifically, the mutations and defects in its regulatory factors (mainly factor H and factor I), as well as the presence of acquired autoantibodies (C3 nephritic factor), which generates an unbridled activation of the system, and ultimately, a deposit of its products at the glomerular level. Its poor prognosis and onset in young populations makes the detailed study of new therapeutic alternatives for this disease essential. Recently eculizumab, an anti-C5 antibody, has demonstrated effectiveness in the treatment of these patients. PMID:24576419

  13. Complement therapeutics in inflammatory diseases: promising drug candidates for C3-targeted intervention.

    PubMed

    Mastellos, D C; Ricklin, D; Hajishengallis, E; Hajishengallis, G; Lambris, J D

    2016-02-01

    There is increasing appreciation that complement dysregulation lies at the heart of numerous immune-mediated and inflammatory disorders. Complement inhibitors are therefore being evaluated as new therapeutic options in various clinical translation programs and the first clinically approved complement-targeted drugs have profoundly impacted the management of certain complement-mediated diseases. Among the many members of the intricate protein network of complement, the central component C3 represents a 'hot-spot' for complement-targeted therapeutic intervention. C3 modulates both innate and adaptive immune responses and is linked to diverse immunomodulatory systems and biological processes that affect human pathophysiology. Compelling evidence from preclinical disease models has shown that C3 interception may offer multiple benefits over existing therapies or even reveal novel therapeutic avenues in disorders that are not commonly regarded as complement-driven, such as periodontal disease. Using the clinically developed compstatin family of C3 inhibitors and periodontitis as illustrative examples, this review highlights emerging therapeutic concepts and developments in the design of C3-targeted drug candidates as novel immunotherapeutics for oral and systemic inflammatory diseases. PMID:26332138

  14. 21 CFR 866.5260 - Complement C3b inactivator immunological test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... immunochemical techniques the complement C3b inactivator (a plasma protein) in serum. Complement is a group of serum proteins that destroy infectious agents. Measurement of complement C3b inactivator aids in...

  15. 21 CFR 866.5260 - Complement C3b inactivator immunological test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... immunochemical techniques the complement C3b inactivator (a plasma protein) in serum. Complement is a group of serum proteins that destroy infectious agents. Measurement of complement C3b inactivator aids in...

  16. 21 CFR 866.5260 - Complement C3b inactivator immunological test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... immunochemical techniques the complement C3b inactivator (a plasma protein) in serum. Complement is a group of serum proteins that destroy infectious agents. Measurement of complement C3b inactivator aids in...

  17. 21 CFR 866.5260 - Complement C3b inactivator immunological test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... immunochemical techniques the complement C3b inactivator (a plasma protein) in serum. Complement is a group of serum proteins that destroy infectious agents. Measurement of complement C3b inactivator aids in...

  18. 21 CFR 866.5260 - Complement C3b inactivator immunological test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... immunochemical techniques the complement C3b inactivator (a plasma protein) in serum. Complement is a group of serum proteins that destroy infectious agents. Measurement of complement C3b inactivator aids in...

  19. Complement C3-Deficient Mice Fail to Display Age-Related Hippocampal Decline.

    PubMed

    Shi, Qiaoqiao; Colodner, Kenneth J; Matousek, Sarah B; Merry, Katherine; Hong, Soyon; Kenison, Jessica E; Frost, Jeffrey L; Le, Kevin X; Li, Shaomin; Dodart, Jean-Cosme; Caldarone, Barbara J; Stevens, Beth; Lemere, Cynthia A

    2015-09-23

    The complement system is part of the innate immune response responsible for removing pathogens and cellular debris, in addition to helping to refine CNS neuronal connections via microglia-mediated pruning of inappropriate synapses during brain development. However, less is known about the role of complement during normal aging. Here, we studied the role of the central complement component, C3, in synaptic health and aging. We examined behavior as well as electrophysiological, synaptic, and neuronal changes in the brains of C3-deficient male mice (C3 KO) compared with age-, strain-, and gender-matched C57BL/6J (wild-type, WT) control mice at postnatal day 30, 4 months, and 16 months of age. We found the following: (1) region-specific and age-dependent synapse loss in aged WT mice that was not observed in C3 KO mice; (2) age-dependent neuron loss in hippocampal CA3 (but not in CA1) that followed synapse loss in aged WT mice, neither of which were observed in aged C3 KO mice; and (3) significantly enhanced LTP and cognition and less anxiety in aged C3 KO mice compared with aged WT mice. Importantly, CA3 synaptic puncta were similar between WT and C3 KO mice at P30. Together, our results suggest a novel and prominent role for complement protein C3 in mediating aged-related and region-specific changes in synaptic function and plasticity in the aging brain. Significance statement: The complement cascade, part of the innate immune response to remove pathogens, also plays a role in synaptic refinement during brain development by the removal of weak synapses. We investigated whether complement C3, a central component, affects synapse loss during aging. Wild-type (WT) and C3 knock-out (C3 KO) mice were examined at different ages. The mice were similar at 1 month of age. However, with aging, WT mice lost synapses in specific brain regions, especially in hippocampus, an area important for memory, whereas C3 KO mice were protected. Aged C3 KO mice also performed better on

  20. Complement C3 gene: Expression characterization and innate immune response in razor clam Sinonovacula constricta.

    PubMed

    Peng, Maoxiao; Niu, Donghong; Wang, Fei; Chen, Zhiyi; Li, Jiale

    2016-08-01

    Complement component 3 (C3) is central to the complement system, playing an important role in immune defense, immune regulation and immune pathology. Several C3 genes have been characterized in invertebrates but very few in shellfish. The C3 gene was identified from the razor clam Sinonovacula constricta, referred to here as Sc-C3. It was found to be highly homologous with the C3 gene of Ruditapes decussatus. All eight model motifs of the C3 gene were found to be included in the thiolester bond and the C345C region. Sc-C3 was widely expressed in all healthy tissues with expression being highest in hemolymph. A significant difference in expression was revealed at the umbo larvae development stage. The expression of Sc-C3 was highly regulated in the hemolymph and liver, with a distinct response pattern being noted after a challenge with Micrococcus lysodeikticus and Vibrio parahemolyticus. It is therefore suggested that a complicated and unique response pathway may be present in S. constricta. Further, serum of S. constricta containing Sc-C3 was extracted. This was activated by LPS or bacterium for verification for function. The more obvious immune function of Sc-C3 was described as an effective membrane rupture in hemocyte cells of rabbit, V. parahemolyticus and Vibrio anguillarum. Thus, Sc-C3 plays an essential role in the immune defense of S. constricta. PMID:27231190

  1. Cleavage of Complement C3b to iC3b on the Surface of Staphylococcus aureus Is Mediated by Serum Complement Factor I

    PubMed Central

    Cunnion, K. M.; Hair, P. S.; Buescher, E. S.

    2004-01-01

    Complement-mediated opsonization of Staphylococcus aureus bearing the dominant capsule serotypes, serotypes 5 and 8, remains incompletely understood. We have previously shown that complement plays a vital role in the efficient phagocytosis of a serotype 5 S. aureus strain and that the opsonic fragments of the central complement protein C3, C3b and iC3b, were present on the bacterial surface after incubation in human serum. In the present studies, C3b and iC3b were found on several serotype 5 and 8 S. aureus strains after incubation in human serum. Using purified classical activation pathway complement proteins and the Western blot assay, we showed that when C3b was generated on the S. aureus surface no iC3b fragments were found, suggesting that other serum proteins may be required for cleaving C3b to iC3b. When C3b-coated S. aureus was incubated with serum factor I, a complement regulatory protein, iC3b was generated. Purified factor H, a serum protein cofactor for factor I, did not enhance factor I-mediated cleavage of C3b. These findings suggest that C3b cleavage to iC3b on S. aureus is mediated by serum factor I and does not require factor H. PMID:15102797

  2. Identification of C3 acceptors responsible for complement activation in Crithidia fasciculata

    SciTech Connect

    Guether, M.L.T.; Travassos, L.R.; Schenkman, S.

    1988-11-01

    Crithidia fasciculata, an insect trypanosomatid is readily lysed by normal human serum at concentrations as low as 3%. Lysis occurs in the presence of Mg+2-EGTA and is antibody independent, indicating that the alternative pathway of complement activation is involved. Analysis of (131I)C3 deposition on C. fasciculata cells using C8-deficient serum, revealed that about 4 x 10(5) C3 molecules bound to each cell. Most of the C3 was bound to cells as C3b, part of it forming high molecular weight complexes, which could be dissociated by methylamine treatment at alkaline pH. To characterize the C3 acceptors on C. fasciculata, surface-iodinated cells were incubated with C8D or heat-inactivated serum, extracted and immunoprecipitated with anti-C3 or anti-arabinogalactan antisera. Analysis of the immunoprecipitated material on SDS gels showed high-molecular weight components, which disappeared after methylamine treatment, giving rise to a component of 200 kDa molecular size. This 200-kDa component corresponded to a purified arabinogalactan complex, which was immunoprecipitated from labeled cell extracts, without incubation with C8D, using anti-arabinogalactan antibodies. These results suggest that the arabinogalactan glycoconjugate is a C3 acceptor in C. fasciculata during complement activation. Purified arabinogalactan complexes were able to inactivate C3 in vitro. Solubilization in KOH to cleave the peptide moiety rendered it unable to inactivate C3. Apparently, the aggregated state of the purified arabinogalactan component at the cell surface is important for C3 deposition and activation.

  3. Regulators of complement activity mediate inhibitory mechanisms through a common C3b-binding mode.

    PubMed

    Forneris, Federico; Wu, Jin; Xue, Xiaoguang; Ricklin, Daniel; Lin, Zhuoer; Sfyroera, Georgia; Tzekou, Apostolia; Volokhina, Elena; Granneman, Joke Cm; Hauhart, Richard; Bertram, Paula; Liszewski, M Kathryn; Atkinson, John P; Lambris, John D; Gros, Piet

    2016-05-17

    Regulators of complement activation (RCA) inhibit complement-induced immune responses on healthy host tissues. We present crystal structures of human RCA (MCP, DAF, and CR1) and a smallpox virus homolog (SPICE) bound to complement component C3b. Our structural data reveal that up to four consecutive homologous CCP domains (i-iv), responsible for inhibition, bind in the same orientation and extended arrangement at a shared binding platform on C3b. Large sequence variations in CCP domains explain the diverse C3b-binding patterns, with limited or no contribution of some individual domains, while all regulators show extensive contacts with C3b for the domains at the third site. A variation of ~100° rotation around the longitudinal axis is observed for domains binding at the fourth site on C3b, without affecting the overall binding mode. The data suggest a common evolutionary origin for both inhibitory mechanisms, called decay acceleration and cofactor activity, with variable C3b binding through domains at sites ii, iii, and iv, and provide a framework for understanding RCA disease-related mutations and immune evasion. PMID:27013439

  4. Complement protein C3 exacerbates prion disease in a mouse model of chronic wasting disease.

    PubMed

    Michel, Brady; Ferguson, Adam; Johnson, Theodore; Bender, Heather; Meyerett-Reid, Crystal; Wyckoff, A Christy; Pulford, Bruce; Telling, Glenn C; Zabel, Mark D

    2013-12-01

    Accumulating evidence shows a critical role of the complement system in facilitating attachment of prions to both B cells and follicular dendritic cells and assisting in prion replication. Complement activation intensifies disease in prion-infected animals, and elimination of complement components inhibits prion accumulation, replication and pathogenesis. Chronic wasting disease (CWD) is a highly infectious prion disease of captive and free-ranging cervid populations that utilizes the complement system for efficient peripheral prion replication and most likely efficient horizontal transmission. Here we show that complete genetic or transient pharmacological depletion of C3 prolongs incubation times and significantly delays splenic accumulation in a CWD transgenic mouse model. Using a semi-quantitative prion amplification scoring system we show that C3 impacts disease progression in the early stages of disease by slowing the rate of prion accumulation and/or replication. The delayed kinetics in prion replication correlate with delayed disease kinetics in mice deficient in C3. Taken together, these data support a critical role of C3 in peripheral CWD prion pathogenesis. PMID:24038599

  5. The Expression Profile of Complement Components in Podocytes.

    PubMed

    Li, Xuejuan; Ding, Fangrui; Zhang, Xiaoyan; Li, Baihong; Ding, Jie

    2016-01-01

    Podocytes are critical for maintaining the glomerular filtration barrier and are injured in many renal diseases, especially proteinuric kidney diseases. Recently, reports suggested that podocytes are among the renal cells that synthesize complement components that mediate glomerular diseases. Nevertheless, the profile and extent of complement component expression in podocytes remain unclear. This study examined the expression profile of complement in podocytes under physiological conditions and in abnormal podocytes induced by multiple stimuli. In total, 23/32 complement component components were detected in podocyte by conventional RT-PCR. Both primary cultured podocytes and immortalized podocytes expressed the complement factors C1q, C1r, C2, C3, C7, MASP, CFI, DAF, CD59, C4bp, CD46, Protein S, CR2, C1qR, C3aR, C5aR, and Crry (17/32), whereas C4, CFB, CFD, C5, C6, C8, C9, MBL1, and MBL2 (9/32) complement factors were not expressed. C3, Crry, and C1q-binding protein were detected by tandem mass spectrometry. Podocyte complement gene expression was affected by several factors (puromycin aminonucleoside (PAN), angiotensin II (Ang II), interleukin-6 (IL-6), and transforming growth factor-β (TGF-β)). Representative complement components were detected using fluorescence confocal microscopy. In conclusion, primary podocytes express various complement components at the mRNA and protein levels. The complement gene expressions were affected by several podocyte injury factors. PMID:27043537

  6. The Expression Profile of Complement Components in Podocytes

    PubMed Central

    Li, Xuejuan; Ding, Fangrui; Zhang, Xiaoyan; Li, Baihong; Ding, Jie

    2016-01-01

    Podocytes are critical for maintaining the glomerular filtration barrier and are injured in many renal diseases, especially proteinuric kidney diseases. Recently, reports suggested that podocytes are among the renal cells that synthesize complement components that mediate glomerular diseases. Nevertheless, the profile and extent of complement component expression in podocytes remain unclear. This study examined the expression profile of complement in podocytes under physiological conditions and in abnormal podocytes induced by multiple stimuli. In total, 23/32 complement component components were detected in podocyte by conventional RT-PCR. Both primary cultured podocytes and immortalized podocytes expressed the complement factors C1q, C1r, C2, C3, C7, MASP, CFI, DAF, CD59, C4bp, CD46, Protein S, CR2, C1qR, C3aR, C5aR, and Crry (17/32), whereas C4, CFB, CFD, C5, C6, C8, C9, MBL1, and MBL2 (9/32) complement factors were not expressed. C3, Crry, and C1q-binding protein were detected by tandem mass spectrometry. Podocyte complement gene expression was affected by several factors (puromycin aminonucleoside (PAN), angiotensin II (Ang II), interleukin-6 (IL-6), and transforming growth factor-β (TGF-β)). Representative complement components were detected using fluorescence confocal microscopy. In conclusion, primary podocytes express various complement components at the mRNA and protein levels. The complement gene expressions were affected by several podocyte injury factors. PMID:27043537

  7. Platelet-associated complement C3 in immune thrombocytopenic purpura

    SciTech Connect

    Myers, T.J.; Kim, B.K.; Steiner, M.; Baldini, M.G.

    1982-05-01

    Platelet-associated C3 (PA-C3) was measured with a quantitative immunofluorescence assay. With this assay, PA-C3 levels were determined for 78 normal volunteers, 30 patients with immune thrombocytopenic purpura (ITP), and 20 patients with nonimmune thrombocytopenias. Platelet-associatd IgG (PA-lgG) levels were also measured with our standard quantitative immunofluorescence assay. All patients with nonimmune thrombocytopenias and ITP in remission had normal PA-C3 levels. Twenty-four patients with active ITP wre classified into 3 groups: 9 (38%) with increased PA-IgG and normal PA-C3 levels, 10 (42%) with elevated PA-C3 and PA-IgG levels, and 5 (20%) with increased PA-C3 values only. A direct correlation was found between PA-C3 and PA-IgG levels. PA-IgG levels were higher in the group of patients with elevated PA-C3 levels than in those with normal values. Platelet survival studies showed reduced survival times of 1.5-2.5 days for the 5 patients with elevated PA-C3 levels only. Elevated PA-C3 levels returned to normal in 7 ITP patients whose platelet counts increased in response to corticosteriod therapy or to splenectomy. Therefore, PA-C3 and PA-IgG assays can be used to identify patients with ITP, to follow their response to therapy, and to classify them into immunologic subgroups similar to red cell classifiation by Coombs' testing in immune hemolytic anemia.

  8. Postoperative atypical hemolytic uremic syndrome associated with complement c3 mutation.

    PubMed

    Matsukuma, Eiji; Imamura, Atsushi; Iwata, Yusuke; Takeuchi, Takamasa; Yoshida, Yoko; Fujimura, Yoshihiro; Fan, Xinping; Miyata, Toshiyuki; Kuwahara, Takashi

    2014-01-01

    Atypical hemolytic uremic syndrome (aHUS) can be distinguished from typical or Shiga-like toxin-induced HUS. The clinical outcome is unfavorable; up to 50% of affected patients progress to end-stage renal failure and 25% die during the acute phase. Multiple conditions have been associated with aHUS, including infections, drugs, autoimmune conditions, transplantation, pregnancy, and metabolic conditions. aHUS in the nontransplant postsurgical period, however, is rare. An 8-month-old boy underwent surgical repair of tetralogy of Fallot. Neurological disturbances, acute renal failure, thrombocytopenia, and microangiopathic hemolytic anemia developed 25 days later, and aHUS was diagnosed. Further evaluation revealed that his complement factor H (CFH) level was normal and that anti-FH antibodies were not detected in his plasma. Sequencing of his CFH, complement factor I, membrane cofactor protein, complement factor B, and thrombomodulin genes was normal. His ADAMTS-13 (a disintegrin-like and metalloprotease with thrombospondin-1 repeats 13) activity was also normal. However, he had a potentially causative mutation (R425C) in complement component C3. Restriction fragment length polymorphism analysis revealed that his father and aunt also had this mutation; however, they had no symptoms of aHUS. We herein report a case of aHUS that developed after cardiovascular surgery and was caused by a complement C3 mutation. PMID:25431709

  9. Tolerance is dependent on complement C3 fragment iC3b binding to antigen-presenting cells

    PubMed Central

    Sohn, Jeong-Hyeon; Bora, Puran S.; Suk, Hye-Jung; Molina, Hector; Kaplan, Henry J.; Bora, Nalini S.

    2007-01-01

    Systemic tolerance can be induced by the introduction of antigen into an immune-privileged site. Here we investigated the role of complement in the induction of tolerance after intraocular injection. We found that the development of antigen-specific tolerance is dependent on a complement activation product. The ligation of the complement C3 activation product iC3b to complement receptor type 3 (the iC3b receptor) on antigen-presenting cells resulted in the sequential production of transforming growth factor-β2 and interleukin-10, which is essential for the induction of tolerance. These observations may extend to the development of both neonatal tolerance and other forms of acquired tolerance. PMID:12514742

  10. Identification of a partial cDNA clone for the C3d/Epstein-Barr virus receptor of human B lymphocytes: homology with the receptor for fragments C3b and C4b of the third and fourth components of complement.

    PubMed

    Weis, J J; Fearon, D T; Klickstein, L B; Wong, W W; Richards, S A; de Bruyn Kops, A; Smith, J A; Weis, J H

    1986-08-01

    Human complement receptor type 2 (CR2) is the B-lymphocyte receptor both for the C3d fragment of the third component of complement and for the Epstein-Barr virus. Amino acid sequence analysis of tryptic peptides of CR2 revealed a strong degree of homology with the human C3b/C4b receptor, CR1. This homology suggested that CR1 gene sequences could be used to detect the CR2 sequences at conditions of low-stringency hybridization. Upon screening a human tonsillar cDNA library with CR1 cDNA sequences, two clones were identified that hybridized at low, but not at high, stringency. Redundant oligonucleotides specific for CR2 sequences were synthesized and used to establish that the two cDNA clones weakly hybridizing with the CR1 cDNA contained CR2 sequences. One of these CR2 cDNA clones hybridized to oligonucleotides derived from two distinct CR2 tryptic peptides, whereas the other, smaller cDNA clone hybridized to oligonucleotides derived from only one of the CR2 peptides. Nucleotide sequence analysis of the CR2 cDNA confirmed that the site of oligonucleotide hybridization was identical to that predicted from the peptide sequence, including flanking sequences not included within the oligonucleotide probes. The CR2-specific cDNA sequences identified a poly(A)+ RNA species of 5 kilobases in RNA extracted from human B cells but did not hybridize to any RNA obtained from the CR2-negative T-cell line HSB-2, thus confirming the appropriate size and tissue-specific distribution for the CR2 mRNA. The striking peptide sequence homology between CR2 and CR1 and the cross-hybridization of the CR2 cDNA with the CR1-specific sequences allow the placement of CR2 in a recently defined gene family of C3- and C4-binding proteins consisting of CR1, C4-binding protein, factor H, and now, CR2. PMID:3016712

  11. Human complement C3 deficiency: Th1 induction requires T cell-derived complement C3a and CD46 activation.

    PubMed

    Ghannam, Arije; Fauquert, Jean-Luc; Thomas, Caroline; Kemper, Claudia; Drouet, Christian

    2014-03-01

    Human T helper type 1 (Th1) responses are essential in defense. Although T cell receptor (TCR) and co-stimulator engagement are indispensable for T cell activation, stimulation of additional receptor pathways are also necessary for effector induction. For example, engagement of the complement regulator CD46 by its ligand C3b generated upon TCR activation is required for IFN-γ production as CD46-deficient patients lack Th1 responses. Utilizing T cells from two C3-deficient patients we demonstrate here that normal Th1 responses also depend on signals mediated by the anaphylatoxin C3a receptor (C3aR). Importantly, and like in CD46-deficient patients, whilst Th1 induction are impaired in C3-deficient patients in vitro, their Th2 responses are unaffected. Furthermore, C3-deficient CD4(+) T cells present with reduced expression of CD25 and CD122, further substantiating the growing notion that complement fragments regulate interleukin-2 receptor (IL-2R) assembly and that disturbance of complement-guided IL-2R assembly contributes to aberrant Th1 effector responses. Lastly, sustained intrinsic production of complement fragments may participate in the Th1 contraction phase as both C3a and CD46 engagement regulate IL-10 co-expression in Th1 cells. These data suggest that C3aR and CD46 activation via intrinsic generation of their respective ligands is an integral part of human Th1 (but not Th2) immunity. PMID:24321396

  12. Genetics Home Reference: complement component 8 deficiency

    MedlinePlus

    ... the membranes surrounding the brain and spinal cord (meningitis). Although meningitis can be life-threatening, individuals with complement component ... leaves affected individuals prone to recurrent episodes of meningitis. Learn more about the genes associated with complement ...

  13. 21 CFR 866.5240 - Complement components immunological test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Complement components immunological test system. 866.5240 Section 866.5240 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... complement components C1q, C1r, C1s, C2, C3, C4, C5, C6, C7, C8, and C9, in serum, other body fluids,...

  14. 21 CFR 866.5240 - Complement components immunological test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Complement components immunological test system. 866.5240 Section 866.5240 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... complement components C1q, C1r, C1s, C2, C3, C4, C5, C6, C7, C8, and C9, in serum, other body fluids,...

  15. 21 CFR 866.5240 - Complement components immunological test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Complement components immunological test system. 866.5240 Section 866.5240 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... complement components C1q, C1r, C1s, C2, C3, C4, C5, C6, C7, C8, and C9, in serum, other body fluids,...

  16. 21 CFR 866.5240 - Complement components immunological test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Complement components immunological test system. 866.5240 Section 866.5240 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... complement components C1q, C1r, C1s, C2, C3, C4, C5, C6, C7, C8, and C9, in serum, other body fluids,...

  17. C3 glomerulopathy–associated CFHR1 mutation alters FHR oligomerization and complement regulation

    PubMed Central

    Tortajada, Agustín; Yébenes, Hugo; Abarrategui-Garrido, Cynthia; Anter, Jaouad; García-Fernández, Jesús M.; Martínez-Barricarte, Rubén; Alba-Domínguez, María; Malik, Talat H.; Bedoya, Rafael; Pérez, Rocío Cabrera; Trascasa, Margarita López; Pickering, Matthew C.; Harris, Claire L.; Sánchez-Corral, Pilar; Llorca, Oscar; Rodríguez de Córdoba, Santiago

    2013-01-01

    C3 glomerulopathies (C3G) are a group of severe renal diseases with distinct patterns of glomerular inflammation and C3 deposition caused by complement dysregulation. Here we report the identification of a familial C3G-associated genomic mutation in the gene complement factor H–related 1 (CFHR1), which encodes FHR1. The mutation resulted in the duplication of the N-terminal short consensus repeats (SCRs) that are conserved in FHR2 and FHR5. We determined that native FHR1, FHR2, and FHR5 circulate in plasma as homo- and hetero-oligomeric complexes, the formation of which is likely mediated by the conserved N-terminal domain. In mutant FHR1, duplication of the N-terminal domain resulted in the formation of unusually large multimeric FHR complexes that exhibited increased avidity for the FHR1 ligands C3b, iC3b, and C3dg and enhanced competition with complement factor H (FH) in surface plasmon resonance (SPR) studies and hemolytic assays. These data revealed that FHR1, FHR2, and FHR5 organize a combinatorial repertoire of oligomeric complexes and demonstrated that changes in FHR oligomerization influence the regulation of complement activation. In summary, our identification and characterization of a unique CFHR1 mutation provides insights into the biology of the FHRs and contributes to our understanding of the pathogenic mechanisms underlying C3G. PMID:23728178

  18. Circulating conversion products of C3 in liver disease. Evidence for in vivo activation of the complement system

    PubMed Central

    Teisberg, P.; Gjone, E.

    1973-01-01

    Circulating conversion products of the third component of human complement (C3) were sought for in different forms of liver disease by the method of antigen–antibody crossed electrophoresis. Immunochemical determinations of C3 and C4 by the single radial immunodiffusion method were performed simultaneously. The conversion product C3b was found in four out of twelve patients with chronic active hepatitis (CAH) and in seven out of nine with primary biliary cirrhosis (PBC). C3b was also seen in a patient with the special form of acute hepatitis characterized by arthritic prodromas and a high titre of hepatitis-associated antigen (HAA) in serum in the acute phase. The group of CAH patients had low serum C3 and C4 regardless of whether C3 breakdown products could be demonstrated or not. In PBC normal serum levels of C3 and C4 were generally found. It is concluded that in some patients with CAH and in a majority of the patients with PBC activation of complement takes place in vivo, possibly on immune complexes deposited in the liver. The serum level of C3 is not a good parameter of immunologic activity in liver disease. ImagesFig. 1 PMID:4201114

  19. Developmentally regulated expression by Trypanosoma cruzi of molecules that accelerate the decay of complement C3 convertases

    SciTech Connect

    Rimoldi, M.T.; Sher, A.; Heiny, A.; Lituchy, A.; Hammer, C.H.; Joiner, K.

    1988-01-01

    The authors recently showed that culture-derived metacyclic trypomastigotes (CMT), but not epimastigotes (Epi), of the Miranda 99 strain of Trypanosoma cruzi evade lysis by the human alternative complement pathway because of inefficient binding of factor B to complement component C3b on the parasite surface. These results suggested that CMT and tissue-culture-derived trypomastigotes (TCT), which also activate the alternative pathway poorly, might produce a molecule capable of interfering with factor B binding to C3b. They now demonstrate that CMT and TCT lysates, as well as molecules spontaneously shed from CMT and TCT but not Epi, accelerate decay of /sup 125/I-labeled factor Bb from the alternative-pathway C3 convertase (C3bBb) assembled on zymosan or Epi and also accelerate decay of the classical-pathway C3 convertase (C4b2a) on sheep erythrocytes. Parasites metabolically labeled with (/sup 35/S)methionine spontaneously shed a limited number of radioactive components, ranging in molecular mass from 86 to 155 kDa for trypomastigotes and 25 to 80 kDa for Epi. Decay-accelerating activity within supernatants is inactivated by papain and is coeluted with /sup 35/S-containing polypeptides on FPLC anion-exchange chromatography, suggesting that the active constituents are protein molecules. Molecules with decay-accelerating activity may explain the developmentally regulated resistance to complement-mediated lysis in infective and vertebrate stages for T. cruzi life cycle.

  20. The Complement C3a Receptor Contributes to Melanoma Tumorigenesis by Inhibiting Neutrophil and CD4+ T Cell Responses.

    PubMed

    Nabizadeh, Jamileh A; Manthey, Helga D; Steyn, Frederik J; Chen, Weiyu; Widiapradja, Alexander; Md Akhir, Fazrena N; Boyle, Glen M; Taylor, Stephen M; Woodruff, Trent M; Rolfe, Barbara E

    2016-06-01

    The complement peptide C3a is a key component of the innate immune system and a major fragment produced following complement activation. We used a murine model of melanoma (B16-F0) to identify a hitherto unknown role for C3a-C3aR signaling in promoting tumor growth. The results show that the development and growth of B16-F0 melanomas is retarded in mice lacking C3aR, whereas growth of established melanomas can be arrested by C3aR antagonism. Flow cytometric analysis showed alterations in tumor-infiltrating leukocytes in the absence of C3aR. Specifically, neutrophils and CD4(+) T lymphocyte subpopulations were increased, whereas macrophages were reduced. The central role of neutrophils was confirmed by depletion experiments that reversed the tumor inhibitory effects observed in C3aR-deficient mice and returned tumor-infiltrating CD4(+) T cells to control levels. Analysis of the tumor microenvironment showed upregulation of inflammatory genes that may contribute to the enhanced antitumor response observed in C3aR-deficient mice. C3aR deficiency/inhibition was also protective in murine models of BRAF(V600E) mutant melanoma and colon and breast cancer, suggesting a tumor-promoting role for C3aR signaling in a range of tumor types. We propose that C3aR activation alters the tumor inflammatory milieu, thereby promoting tumor growth. Therapeutic inhibition of C3aR may therefore be an effective means to trigger an antitumor response in melanoma and other cancers. PMID:27183625

  1. Nomenclature for human complement component C2*

    PubMed Central

    1992-01-01

    This note describes the designations for variants of the human complement component C2, which were approved by the Nomenclature Committee of the International Union of Immunological Societies (IUIS). PMID:1394787

  2. Role of complement receptor type 2 and endogenous complement in the humoral immune response to conjugates of complement C3d and pneumococcal serotype 14 capsular polysaccharide.

    PubMed

    Mitsuyoshi, Joyce K; Hu, Yong; Test, Samuel T

    2005-11-01

    Conjugation of the complement fragment C3d to both T-cell-dependent (TD) protein and T-cell-independent type 2 (TI-2) polysaccharide antigens enhances the humoral immune response in mice immunized with either type of antigen. However, the ability of C3d-protein conjugates to enhance the antibody response in mice deficient in complement receptor types 1 and 2 (CR1 and CR2) has raised questions about the role of C3d-CR2 interactions in the adjuvant effect of C3d. In this study, we examined the role of CR2 binding and endogenous complement activation in the antibody response to conjugates of C3d and serotype 14 pneumococcal capsular polysaccharide (PPS14). To block binding of PPS14-C3d conjugates to CR2, mice were immunized with a mixture of vaccine and (CR2)2-immunoglobulin G1 (IgG1). Mice receiving (CR2)2-IgG1 at the time of primary immunization had a marked reduction in the primary anti-PPS14 antibody response but an enhanced secondary anti-PPS14 response, suggesting that C3d-CR2 interactions are required for the primary response but can have negative effects on the memory response. Further, compared with mice receiving PPS14-C3d having a high C3d/PPS14 ratio, mice immunized with PPS14-C3d with low C3d/PPS14 ratios had an enhanced secondary antibody response. Treatment of mice with cobra venom factor to deplete complement had insignificant effects on the antibody response to PPS14-C3d. Experiments with CBA/N xid mice confirmed that PPS14-C3d conjugates retain the characteristics of TI-2 rather than TD antigens. Thus, the adjuvant effect of C3d conjugated to PPS14 requires C3d-CR2 interactions, does not require activation of endogenous complement, and is not mediated by TD carrier effects. PMID:16239528

  3. Complement Peptide C3a Promotes Astrocyte Survival in Response to Ischemic Stress.

    PubMed

    Shinjyo, Noriko; de Pablo, Yolanda; Pekny, Milos; Pekna, Marcela

    2016-07-01

    Astrocytes are the most numerous cells in the central nervous system with a range of homeostatic and regulatory functions. Under normal conditions as well as after ischemia, astrocytes promote neuronal survival. We have previously reported that the complement-derived peptide C3a stimulates neuronal differentiation of neural progenitor cells and protects the immature brain tissue against hypoxic-ischemic injury. Here, we studied the effects of C3a on the response of mouse cortical astrocytes to ischemia. We have found that chemical ischemia, induced by combined inhibition of oxidative phosphorylation and glycolysis, upregulates the expression of C3a receptor in cultured primary astrocytes. C3a treatment protected wild-type but not C3a receptor-deficient astrocytes from cell death induced by chemical ischemia or oxygen-glucose deprivation by reducing ERK signaling and caspase-3 activation. C3a attenuated ischemia-induced upregulation of glial fibrillary acidic protein; however, the protective effects of C3a were not dependent on the presence of the astrocyte intermediate filament system. Pre-treatment of astrocytes with C3a during recovery abrogated the ischemia-induced neuroprotective phenotype of astrocytes. Jointly, these results provide the first evidence that the complement peptide C3a modulates the response of astrocytes to ischemia and increases their ability to cope with ischemic stress. PMID:25972241

  4. Epstein Barr virus/complement C3d receptor is an interferon alpha receptor.

    PubMed

    Delcayre, A X; Salas, F; Mathur, S; Kovats, K; Lotz, M; Lernhardt, W

    1991-04-01

    Interferon alpha contains a sequence motif similar to the complement receptor type two (CR2/CD21) binding site on complement fragment C3d. Antibodies against a peptide with the CR2 binding sequence on C3d react with a peptide carrying the IFN alpha CR2 binding motif (residues 92-99) and with recombinant IFN alpha. The IFN alpha-derived peptide, as well as recombinant IFN alpha, inhibits C3bi/C3d interaction with CR2 on the Burkitt lymphoma Raji. The direct interaction of IFN alpha and CR2 is inhibited by polyclonal anti-IFN alpha, anti-CR2 and anti-C3d peptide antibodies as well as by C3bi/C3d, EBV coat protein gp350/220 and IFN but not by IFN gamma. [125I]IFN alpha binding to Raji cells is inhibited by polyclonal anti-IFN alpha and anti-CR2 antibodies, by peptides with the CR2 binding motif and partially by C3bi/C3d. Monoclonal anti-CR2 antibody HB5, but not OKB-7, blocks IFN alpha binding to Raji cells. CR2 or CR2-like molecules may therefore be the major IFN alpha receptors on B lymphocytes. PMID:1849076

  5. Compstatin: a C3-targeted complement inhibitor reaching its prime for bedside intervention.

    PubMed

    Mastellos, Dimitrios C; Yancopoulou, Despina; Kokkinos, Petros; Huber-Lang, Markus; Hajishengallis, George; Biglarnia, Ali R; Lupu, Florea; Nilsson, Bo; Risitano, Antonio M; Ricklin, Daniel; Lambris, John D

    2015-04-01

    There is a growing awareness that complement plays an integral role in human physiology and disease, transcending its traditional perception as an accessory system for pathogen clearance and opsonic cell killing. As the list of pathologies linked to dysregulated complement activation grows longer, it has become clear that targeted modulation of this innate immune system opens new windows of therapeutic opportunity for anti-inflammatory drug design. Indeed, the introduction of the first complement-targeting drugs has reignited a vibrant interest in the clinical translation of complement-based inhibitors. Compstatin was discovered as a cyclic peptide that inhibits complement activation by binding C3 and interfering with convertase formation and C3 cleavage. As the convergence point of all activation pathways and a molecular hub for crosstalk with multiple pathogenic pathways, C3 represents an attractive target for therapeutic modulation of the complement cascade. A multidisciplinary drug optimization effort encompassing rational 'wet' and in silico synthetic approaches and an array of biophysical, structural and analytical tools has culminated in an impressive structure-function refinement of compstatin, yielding a series of analogues that show promise for a wide spectrum of clinical applications. These new derivatives have improved inhibitory potency and pharmacokinetic profiles and show efficacy in clinically relevant primate models of disease. This review provides an up-to-date survey of the drug design effort placed on the compstatin family of C3 inhibitors, highlighting the most promising drug candidates. It also discusses translational challenges in complement drug discovery and peptide drug development and reviews concerns related to systemic C3 interception. PMID:25678219

  6. The relationship between complement factor C3, APOE ε4, amyloid and tau in Alzheimer's disease.

    PubMed

    Bonham, Luke W; Desikan, Rahul S; Yokoyama, Jennifer S

    2016-01-01

    Inflammation is becoming increasingly recognized as an important contributor to Alzheimer's disease (AD) pathogenesis. As a part of the innate immune system, the complement cascade enhances the body's ability to destroy and remove pathogens and has recently been shown to influence Alzheimer's associated amyloid and tau pathology. However, little is known in humans about the effects of the complement system and genetic modifiers of AD risk like the ε4 allele of apolioprotein E (APOE ε4) on AD pathobiology. We evaluated cerebrospinal fluid (CSF) protein levels from 267 individuals clinically diagnosed as cognitively normal, mild cognitive impairment, and AD. Using linear models, we assessed the relationship between APOE ε4 genotype, CSF Complement 3 (C3), CSF amyloid-β (amyloid) and CSF hyperphosphorylated tau (ptau). We found a significant interaction between APOE ε4 and CSF C3 on both CSF amyloid and CSF ptau. We also found that CSF C3 is only associated with CSF ptau after accounting for CSF amyloid. Our results support a conceptual model of the AD pathogenic cascade where a synergistic relationship between the complement cascade (C3) and APOE ε4 results in elevated Alzheimer's neurodegeneration and in turn, amyloid further regulates the effect of the complement cascade on downstream tau pathology. PMID:27357286

  7. An extended mini-complement factor H molecule ameliorates experimental C3 glomerulopathy

    PubMed Central

    Nichols, Eva-Maria; Barbour, Thomas D; Pappworth, Isabel Y; Wong, Edwin K S; Palmer, Jeremy M; Sheerin, Neil S; Pickering, Matthew C; Marchbank, Kevin J

    2015-01-01

    Abnormal regulation of the complement alternative pathway is associated with C3 glomerulopathy. Complement factor H is the main plasma regulator of the alternative pathway and consists of 20 short consensus repeat (SCR) domains. Although recombinant full-length factor H represents a logical treatment for C3 glomerulopathy, its production has proved challenging. We and others have designed recombinant mini-factor H proteins in which ‘non-essential' SCR domains have been removed. Here, we report the in vitro and in vivo effects of a mini-complement factor H protein, FH1–5^18–20, using the unique factor H–deficient (Cfh−/−) mouse model of C3 glomerulopathy. FH1–5^18–20 is comprised of the key complement regulatory domains (SCRs 1–5) linked to the surface recognition domains (SCRs 18–20). Intraperitoneal injection of FH1–5^18–20 in Cfh−/− mice reduced abnormal glomerular C3 deposition, similar to full-length factor H. Systemic effects on plasma alternative pathway control were comparatively modest, in association with a short half-life. Thus, FH1–5^18–20 is a potential therapeutic agent for C3 glomerulopathy and other renal conditions with alternative pathway-mediated tissue injury. PMID:26221753

  8. Analysis of complement C3 deposition and degradation on Klebsiella pneumoniae.

    PubMed Central

    Albertí, S; Alvarez, D; Merino, S; Casado, M T; Vivanco, F; Tomás, J M; Benedí, V J

    1996-01-01

    The majority of Klebsiella pneumoniae serum-resistant strains activate complement and bind C3b, the opsonic fragment of C3, without C5b-9 formation and bacterial killing. The mechanisms leading to C3b deposition without cell death were studied, and the results indicate that serum-resistant strains activate principally the alternative pathway and that serum-sensitive strains activate both the alternative and classical pathways. Bacterial molecules implicated in C3b deposition are the outer membrane porin proteins and smooth and rough lipopolysaccharides. Porins activate both complement pathways, and the rough lipopolysaccharide activates the classical pathway, causing deposition of C3b in serum-sensitive strains. The smooth lipopolysaccharide of serum-resistant strains activates only the alternative pathway, impeding the binding of C1q to porins (S. Albertí, G. Marqués, S. Camprubí, S. Merino, J. M. Tomás, F. Vivanco, and V. J. Benedí, Infect. Immun. 61:852-860, 1993; S. Albertí, F. Rodríguez-Quinónes, T. Schirmer, G. Rummel, J. M. Tomás, J. P. Rosenbusch, and V. J. Benedí, Infect. Immun. 63:903-910, 1995) and rough lipopolysaccharide molecules and thereby preventing activation of the classical pathway. After its deposition, C3b is quickly degraded to iC3b on both types of strains, but the higher-level deposition of C3b on serum-sensitive strains, resulting from activation of both the alternative and classical complement pathways, supports further complement activation and killing of serum-sensitive strains. PMID:8890232

  9. Antiphospholipid Antibodies are Associated with Low Levels of Complement C3 and C4 in Patients with Systemic Lupus Erythematosus.

    PubMed

    Garabet, L; Gilboe, I-M; Mowinckel, M-C; Jacobsen, A F; Mollnes, T E; Sandset, P M; Jacobsen, E-M

    2016-08-01

    Complement activation and low complement levels are common in systemic lupus erythematosus (SLE). Antiphospholipid antibodies (aPL) are found in about 30-40% of patients with SLE. This study aimed to investigate the association between aPL and complement levels in patients with SLE. Serum samples were collected from 269 patients with SLE enrolled in the Norwegian Systemic Connective Tissue and Vasculitis Registry (NOSVAR) during 2003-2009, and from 353 controls. All samples were analysed for anti-β2 glycoprotein 1 (anti-β2GP1) and anticardiolipin antibodies (aCL), C-reactive protein (CRP) and complement components C3 and C4. Median CRP level was significantly higher in cases than in controls (2.06 versus 0.90 mg/l; P < 0.0001). No significant difference in CRP was found between SLE patients with or without aPL (2.09 versus 1.89; P = 0.665). Median C3 levels were similar in cases (1.03 g/l) and controls (1.00 g/l), whereas median C4 levels were 0.16 g/l in cases versus. 0.19 in controls (P < 0.0001). However, aPL-positive SLE patients had significantly lower median C3 levels (0.92 versus. 1.07 g/l; P = 0.001) and C4 levels (0.11 versus 0.16 g/l; P < 0.0001) compared to aPL-negative patients. Lower C3 and C4 values in aPL-positive SLE patients may reflect a higher consumption of C3 and C4 due to more pronounced complement activation in aPL-positive SLE patients compared to SLE patients without aPL. PMID:27135178

  10. Complement C3 is expressed by mast cells in cutaneous vasculitis and is degraded by chymase.

    PubMed

    Lipitsä, Tiina; Naukkarinen, Anita; Laitala, Joel; Harvima, Ilkka T

    2016-10-01

    The complement factor C3 and chymase released from tryptase(+), chymase(+) mast cells may be involved in the pathogenesis of cutaneous leukocytoclastic vasculitis. To study whether mast cells contain C3 in vasculitis and whether chymase interacts with C3, cryosections from vasculitis biopsies were double-stained histochemically for C3c in tryptase(+) mast cells, as well as for chymase and vessel wall C3c, or they were treated with 5 µg/ml rh-chymase for 24 h followed by immunofluorescence (IF) analysis of C3c, IgG, IgM and IgA. The effect of rh-chymase on purified human C3, C3a and IgG was studied using SDS-PAGE electrophoresis and LAD2 mast cell cultures. The results show that 34.2 ± 17.9, 37.4 ± 15.5 and 43.4 ± 18.6 % (mean ± SD) of the mast cells express C3c immunoreactivity in the healthy skin, initial petechial (IP) and palpable purpura (PP) lesions, respectively. About 9.4-12.1 % of the chymase(+) mast cells were in apparent contact with C3c(+) vessels in IP and PP. The treatment of cryosections with rh-chymase decreased the IF staining of C3c, but not that of immunoglobulins. In SDS-PAGE, 1-10 µg/ml rh-chymase degraded the alpha- and beta-chains of C3, but did not degrade IgG. Unexpectedly, the rh-chymase treatment of C3 produced fragments that resulted in the release of tryptase and histamine from LAD2 cells. However, rh-chymase degraded C3a and consequently inhibited C3a activity on LAD2. In conclusion, mast cells can be one source for C3 in the early and late phases of vasculitis pathogenesis. However, rh-chymase degraded native C3, vessel wall C3c, and biologically active C3a. Therefore, chymase may control C3-related pathology. PMID:27465068

  11. Regulation by retinoic acid of acylation-stimulating protein and complement C3 in human adipocytes.

    PubMed Central

    Scantlebury, T; Sniderman, A D; Cianflone, K

    2001-01-01

    Acylation-stimulating protein (ASP), a product of complement C3, stimulates triacylglycerol synthesis in adipocytes. Previous studies have identified transthyretin, associated with chylomicrons, as a stimulator of C3 and ASP production. Since both transthyretin and chylomicrons transport retinyl ester/retinol, our goal was to investigate whether retinoic acid (RA) could be a potential hormonal mediator of the effect. Inhibitors of protein synthesis and protein secretion eliminated the stimulatory effects of chylomicrons on both C3 and ASP production in human differentiated adipocytes, suggesting that de novo protein synthesis and secretion are both required. Incubation with chylomicrons increased C3 mRNA levels (37+/-1.5%). RA alone or with chylomicrons had a stimulatory effect on C3 production (29-fold at 16.6 nM RA) and ASP production. An RA receptor antagonist blocked stimulation of C3 mRNA and C3 secretion by both RA and chylomicrons. Finally, RA and chylomicrons activated a 1.8 kb C3-promoter-luciferase construct transfected into 3T3-F442 and 3T3-L1 cells (by 41+/-0.2% and 69+/-0.3% respectively), possibly via RA receptor half-sites identified by sequence analysis. This is the first evidence documenting stimulation by RA of the C3 gene. Thus we propose RA as a novel cellular trigger in chylomicrons that subsequently results in increased ASP production by adipocytes after a meal. PMID:11368771

  12. Complete absence of the third component of complement in man.

    PubMed Central

    Ballow, M; Shira, J E; Harden, L; Yang, S Y; Day, N K

    1975-01-01

    A 4-yr-old female patient who has recurrent infections with encapsulated bacteria and gramnegative organisms was found to have a complete absence of total hemolytic complement and C3. Total hemolytic complement was reconstituted by the addition of functionally pure C3. With the exception of a moderately reduced homolytic C4, all other C components, measured homolytically and by radial immunodiffusion, were present in normal amounts. By Ouchterlong analysis, the patient's serum contained C3b inactivator and properdin but no antigenic C3. Activation of the alternate pathway was examined by purified cobra venom factor (CVF) and inulin. Neither of these substances led to activation of properdin factor B to B. On addition of partially purified Cordis C3, in four out of four instances and with different preparations of Cordis C3, activation of factor B to B occurred in the inulin-serum-C3 mixture. In contrast, activation of factor B to B occurred only once out of four times with CVF-serum-C3 mixtures. Immune adherence was found to be normal in the patient's serum and could be removed by anti-C4 antiserum of hydrazine treatment. A marked opsonic defect was present against Escherichia coli. Serum bactericidal activity against a rough strain of E. coli was also defective. The ability to mobilize an infalmmatory response was examined by Rebuck skin window technique. A delay in neutrophil migration occurred until the 6th h. In vitro lymphocyte transformation and serum immunoglobulins were normal. The proportion of peripheral blood T cells forming spontaneous sheep erythrocyte rosettes and the percentage of B cells forming EAC rosettes by the C3 receptor were normal. The significance of the absence of C3 in our patient is emphasized by the increased number of infections with encapsulated bacteria and the decreased functional biological activities of the C system, important in host defense mechanism(s). Images PMID:1159084

  13. Effects of a recombinant complement component C3b functional fragment α2MR (α2-macroglobulin receptor) additive on the immune response of juvenile orange-spotted grouper (Epinephelus coioides) after the exposure to cold shock challenge.

    PubMed

    Luo, Sheng-Wei; Cai, Luo; Qi, Zeng-Hua; Wang, Cong; Liu, Yuan; Wang, Wei-Na

    2015-08-01

    The effects of Ec-α2MR (Epinephelus coiodes-α2-macroglobulin receptor) on growth performance, enzymatic activity, respiratory burst, MDA level, total antioxidant capacity, DPPH radical scavenging percentage and immune-related gene expressions of the juvenile orange-spotted grouper were evaluated. The commercial diet supplemented with α2MR additive was used to feed the orange-spotted grouper for six weeks. Although a slight increase was observed in the specific growth rate, survival rate and weight gain, no significance was observed among different group. After the feeding trial, the groupers were exposed to cold stress. Respiratory burst activity and MDA level decreased significantly in α2MR additive group by comparing with the control and additive control group, while a sharp increase of ACP activity, ALP activity, total antioxidant capacity and DPPH radial scavenging percentage was observed in α2MR additive group. qRT-PCR analyses confirmed that the up-regulated mRNA expressions of C3, TNF1, TNF2, IL-6, CTL, LysC, SOD1 and SOD2 were observed in α2MR additive group at 20 °C. These results showed that α2MR additive may moderate the immune response in grouper following cold shock challenge. PMID:25917969

  14. Familial C3 glomerulonephritis associated with mutations in the gene for complement factor B.

    PubMed

    Imamura, Hideaki; Konomoto, Takao; Tanaka, Etsuko; Hisano, Satoshi; Yoshida, Yoko; Fujimura, Yoshihiro; Miyata, Toshiyuki; Nunoi, Hiroyuki

    2015-05-01

    We report the first case of familial C3 glomerulonephritis (C3GN) associated with mutations in the gene for complement factor B (CFB). A 12-year-old girl was diagnosed with biopsy-proven C3GN. Her mother had a history of treatment for membranoproliferative glomerulonephritis, and her brother had hypocomplementemia without urinary abnormalities. DNA analysis revealed heterozygosity for CFB p.S367R in the patient, mother and brother. Evaluation of the structure-function relationship supports that this mutation has gain-of-function effects in CFB. The present case suggests that CFB has an important role in the etiology of C3GN and provides a new insight into anticomplement therapy approaches. PMID:25758434

  15. Complement Fragment C3a Controls Mutual Cell Attraction during Collective Cell Migration

    PubMed Central

    Carmona-Fontaine, Carlos; Theveneau, Eric; Tzekou, Apostolia; Tada, Masazumi; Woods, Mae; Page, Karen M.; Parsons, Maddy; Lambris, John D.; Mayor, Roberto

    2011-01-01

    Summary Collective cell migration is a mode of movement crucial for morphogenesis and cancer metastasis. However, little is known about how migratory cells coordinate collectively. Here we show that mutual cell-cell attraction (named here coattraction) is required to maintain cohesive clusters of migrating mesenchymal cells. Coattraction can counterbalance the natural tendency of cells to disperse via mechanisms such as contact inhibition and epithelial-to-mesenchymal transition. Neural crest cells are coattracted via the complement fragment C3a and its receptor C3aR, revealing an unexpected role of complement proteins in early vertebrate development. Loss of coattraction disrupts collective and coordinated movements of these cells. We propose that coattraction and contact inhibition act in concert to allow cell collectives to self-organize and respond efficiently to external signals, such as chemoattractants and repellents. PMID:22118769

  16. Capillary Deposition of Complement C4d and C3d in Chinese Renal Allograft Biopsies

    PubMed Central

    Lv, Rong; Zhang, Wei; Han, Fei; Liu, Guangjun; Xie, Wenqing

    2015-01-01

    Background. C3d is a product of both the classic and the alternative complement cascades; however, few studies have addressed the role of C3d in renal biopsies and its relationship with long-term graft survival rate is not very clear. Methods. 94 patients with biopsy-proven acute rejection episodes were included in the study. We investigated the associations between histological findings, clinical examinations, and outcome. Results. The overall prevalence for C4dPTC and C3dPTC was 42.6% and 29.8%. There was a significant association between C3dPTC and C4dPTC (P < 0.001). C3dPTC and C4dPTC were related with histological types (P = 0.024 and P < 0.001, resp.). The long-term survival rate for C4dPTC positive transplants was lower than that of C4dPTC negative transplants, but it was not statistic significant in our study (P = 0.150). The survival rate of C3dPTC positive group was much lower than the negative group (P = 0.014). Patients with double positives for C4dPTC and C3dPTC exhibited the lowest survival rate significantly different from those of the C3dPTC only and C4dPTC only groups (P = 0.01 and P = 0.0037). Conclusions. This longitudinal cohort study has demonstrated that C3d deposition in the PTC was closely related to renal dysfunction and pathological changes. PMID:25821339

  17. Understanding the complement-mediated glomerular diseases: focus on membranoproliferative glomerulonephritis and C3 glomerulopathies.

    PubMed

    Lionaki, Sophia; Gakiopoulou, Hara; Boletis, John N

    2016-09-01

    An enhanced understanding of the role of complement in the pathogenesis of membranoproliferative glomerulonephritis has led to reclassification of the latter into immunoglobulin-mediated and non-immunoglobulin-mediated disease. The new classification schema resulted in improved diagnostic clinical algorithms, while it brought into light again the diseases, which are characterized by the presence of glomerular deposits, composed predominantly by C3, in the absence of significant amounts of immunoglobulins in renal biopsy, namely, C3 glomerulopathies (dense deposit disease and C3 glomerulonephritis). Despite the lack of randomized controlled trials following the advances in the understanding of the pathogenetic pathways involved in membranoproliferative glomerulonephritis, it is important that the new mechanistic approach has opened new roads for the exploration and discovery of targeted therapies. PMID:27356907

  18. Pneumococcal polysaccharides complexed with C3d bind to human B lymphocytes via complement receptor type 2.

    PubMed Central

    Griffioen, A W; Rijkers, G T; Janssens-Korpela, P; Zegers, B J

    1991-01-01

    The immunoregulatory function of the complement system has been the focus of many investigations. In particular, fragments of complement factor C3 have been shown to play a role in B-lymphocyte activation and proliferation, lymphokine production, and the generation of in vitro antibody production. Purified pneumococcal polysaccharides (PS) can induce direct activation of C3 via the alternative pathway. Using sera of C1q-deficient patients and healthy subjects, we demonstrated that C3d, a split product of C3 that is generated after degradation of iC3b, can be bound to PS antigens. The binding of C3d to PS can occur in the absence of specific antibodies. Subsequently, we showed that PS complexed with C3d can be recognized by complement receptor type 2 that is expressed on B cells. Treatment of B cells with a monoclonal antibody recognizing the C3d-binding site of complement receptor type 2 reduces the binding of PS-C3d to the cells. In addition, we showed that PS4 complexed with C3d exerted an increased immunogenicity compared with free PS4. Our results show that the complement system plays a role in the activation of PS-specific B cells, carrying membrane receptors for C3d. Consequently, the complement system plays a regulatory role in the antibody response to T-cell-independent type 2 antigens such as PS. PMID:1826897

  19. Regulation of C3 Activation by the Alternative Complement Pathway in the Mouse Retina.

    PubMed

    Williams, Jennifer A E; Stampoulis, Dimitris; Gunter, Chloe E; Greenwood, John; Adamson, Peter; Moss, Stephen E

    2016-01-01

    The purpose of this study was to examine the retinas of mice carrying hemizygous and null double deletions of Cfb-/- and Cfh-/-, and to compare these with the single knockouts of Cfb, Cfh and Cfd. Retinas were isolated from wild type (WT), Cfb-/-/Cfh-/-, Cfb-/-/Cfh+/-, Cfh-/-/Cfb+/-, Cfb-/-, Cfh-/- Cfd-/-, and Cfd+/- mice. Complement proteins were evaluated by western blotting, ELISA and immunocytochemistry, and retinal morphology was assessed using toluidine blue stained semi-thin sections. WT mice showed staining for C3 and its breakdown products in the retinal vasculature and the basal surface of the retinal pigment epithelium (RPE). Cfb-/- mice exhibited a similar C3 staining pattern to WT in the retinal vessels but a decrease in C3 and its breakdown products at the basal surface of the RPE. Deletion of both Cfb and Cfh restored C3 to levels similar to those observed in WT mice, however this reversal of phenotype was not observed in Cfh-/-/Cfb+/- or Cfb-/-/Cfh+/- mice. Loss of CFD caused an increase in C3 and a decrease in C3 breakdown products along the basal surface of the RPE. Overall the retinal morphology and retinal vasculature did not appear different across the various genotypes. We observed that C3 accumulates at the basal RPE in Cfb-/-, Cfb-/-/Cfh-/-, Cfb-/-/Cfh+/-, Cfd-/- and WT mice, but is absent in Cfh-/- and Cfh-/-/Cfb+/- mice, consistent with its consumption in the serum of mice lacking CFH when CFB is present. C3 breakdown products along the surface of the RPE were either decreased or absent when CFB, CFH or CFD was deleted or partially deleted. PMID:27564415

  20. Regulation of C3 Activation by the Alternative Complement Pathway in the Mouse Retina

    PubMed Central

    Williams, Jennifer A. E.; Stampoulis, Dimitris; Gunter, Chloe E.; Greenwood, John; Adamson, Peter

    2016-01-01

    The purpose of this study was to examine the retinas of mice carrying hemizygous and null double deletions of Cfb-/- and Cfh-/-, and to compare these with the single knockouts of Cfb, Cfh and Cfd. Retinas were isolated from wild type (WT), Cfb-/-/Cfh-/-, Cfb-/-/Cfh+/-, Cfh-/-/Cfb+/-, Cfb-/-, Cfh-/- Cfd-/-, and Cfd+/- mice. Complement proteins were evaluated by western blotting, ELISA and immunocytochemistry, and retinal morphology was assessed using toluidine blue stained semi-thin sections. WT mice showed staining for C3 and its breakdown products in the retinal vasculature and the basal surface of the retinal pigment epithelium (RPE). Cfb-/- mice exhibited a similar C3 staining pattern to WT in the retinal vessels but a decrease in C3 and its breakdown products at the basal surface of the RPE. Deletion of both Cfb and Cfh restored C3 to levels similar to those observed in WT mice, however this reversal of phenotype was not observed in Cfh-/-/Cfb+/- or Cfb-/-/Cfh+/- mice. Loss of CFD caused an increase in C3 and a decrease in C3 breakdown products along the basal surface of the RPE. Overall the retinal morphology and retinal vasculature did not appear different across the various genotypes. We observed that C3 accumulates at the basal RPE in Cfb-/-, Cfb-/-/Cfh-/-, Cfb-/-/Cfh+/-, Cfd-/- and WT mice, but is absent in Cfh-/- and Cfh-/-/Cfb+/- mice, consistent with its consumption in the serum of mice lacking CFH when CFB is present. C3 breakdown products along the surface of the RPE were either decreased or absent when CFB, CFH or CFD was deleted or partially deleted. PMID:27564415

  1. Complement component 3: a new paradigm in tuberculosis vaccine.

    PubMed

    De La Fuente, José; Gortázar, Christian; Juste, Ramón

    2016-01-01

    Vaccines are critical for the control of tuberculosis (TB) affecting humans and animals worldwide. First-generation vaccines protect from active TB but new vaccines are required to protect against pulmonary disease and infection. Recent advances in post-genomics technologies have allowed the characterization of host-pathogen interactions to discover new protective antigens and mechanisms to develop more effective vaccines against TB. Studies in the wild boar model resulted in the identification of complement component 3 (C3) as a natural correlate of protection against TB. Oral immunization with heat-inactivated mycobacteria protected wild boar against TB and showed that C3 plays a central role in protection. These results point at C3 as a target to develop novel vaccine formulations for more effective protection against TB in humans and animals. PMID:26605515

  2. Synthesis of classical pathway complement components by chondrocytes.

    PubMed Central

    Bradley, K; North, J; Saunders, D; Schwaeble, W; Jeziorska, M; Woolley, D E; Whaley, K

    1996-01-01

    Using immunohistochemical studies, C1q, C1s, C4 and C2 were detected in chondrocytes in normal human articular cartilage and macroscopically normal articular cartilage from the inferior surfaces of hip joints of patients with osteoarthritis. Using reverse-transcribed polymerase chain reaction (RT-PCR), mRNA for C1q, C1s, C4 and C2 was also detected in RNA extracted from articular cartilage. C1r, C3, C1-inhibitor, C4-binding protein and factor I were not detected by either technique. Articular chondrocytes cultured in vitro synthesized C1r, C1s, C4, C2, C3 and C1-inhibitor but not C1q, C4-binding protein or factor I, as assessed by enzyme-linked immunosorbent assay (ELISA) and Northern blot analysis. Thus cultured articular chondrocytes have a complement profile that is similar to that of cultured human fibroblasts rather than that of articular chondrocytes in vivo. Complement synthesis in cultured chondrocytes was modulated by the cytokines interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma), showing that cytokines can probably regulate complement synthesis in intact cartilage. The possible roles of local synthesis of complement components by chondrocytes in matrix turnover and the regulation chondrocyte function are discussed. Images Figure 1 Figure 2 Figure 4 PMID:8881771

  3. Peroxisome Proliferator-activated Receptor α Positively Regulates Complement C3 Expression but Inhibits Tumor Necrosis Factor α-mediated Activation of C3 Gene in Mammalian Hepatic-derived Cells*

    PubMed Central

    Mogilenko, Denis A.; Kudriavtsev, Igor V.; Shavva, Vladimir S.; Dizhe, Ella B.; Vilenskaya, Ekaterina G.; Efremov, Alexander M.; Perevozchikov, Andrej P.; Orlov, Sergey V.

    2013-01-01

    Complement C3 is a pivotal component of three cascades of complement activation. The liver is the main source of C3 in circulation and expression and secretion of C3 by hepatocytes is increased during acute inflammation. However, the mechanism of the regulation of the C3 gene in hepatocytes is not well elucidated. We showed that the C3 gene is the direct target for peroxisome proliferator-activated receptor α (PPARα) in human hepatoma HepG2 cells and mouse liver. Using PPARα siRNA and synthetic PPARα agonist WY-14643 and antagonist MK886 we showed that activation of PPARα results in up-regulation of C3 gene expression and protein secretion by HepG2 cells. The PPAR response element (PPRE), which is able to bind PPARα in vitro and in vivo, was found in the human C3 promoter. PPRE is conserved between human and mouse, and WY-14643 stimulates mouse C3 expression in the liver. TNFα increases C3 gene via NF-κB and, to a lesser extent, MEK1/2 signaling pathways, whereas TNFα-mediated stimulation of C3 protein secretion depends on activation of MEK1/2, p38, and JNK in HepG2 cells. Activation of PPARα abolishes TNFα-mediated up-regulation of C3 gene expression and protein secretion due to interference with NF-κB via PPRE-dependent mechanism in HepG2 cells. TNFα decreases PPARα protein content via NF-κB and MEK1/2 signaling pathways and inhibits PPARα binding with the human C3 promoter in HepG2 cells. These results suggest novel mechanism controlling C3 expression in hepatocytes during acute phase inflammation and demonstrate a crosstalk between PPARα and TNFα in the regulation of complement system. PMID:23168409

  4. Functional Variant in Complement C3 Gene Promoter and Genetic Susceptibility to Temporal Lobe Epilepsy and Febrile Seizures

    PubMed Central

    Perroud, Nader; Ponsole-Lenfant, Magali; Cillario, Jennifer; Roll, Patrice; Roeckel-Trevisiol, Nathalie; Crespel, Ariel; Balzar, Jorg; Schlachter, Kurt; Gruber-Sedlmayr, Ursula; Pataraia, Ekaterina; Baumgartner, Christoph; Zimprich, Alexander; Zimprich, Fritz; Malafosse, Alain; Szepetowski, Pierre

    2010-01-01

    Background Human mesial temporal lobe epilepsies (MTLE) represent the most frequent form of partial epilepsies and are frequently preceded by febrile seizures (FS) in infancy and early childhood. Genetic associations of several complement genes including its central component C3 with disorders of the central nervous system, and the existence of C3 dysregulation in the epilepsies and in the MTLE particularly, make it the C3 gene a good candidate for human MTLE. Methodology/Principal Findings A case-control association study of the C3 gene was performed in a first series of 122 patients with MTLE and 196 controls. Four haplotypes (HAP1 to 4) comprising GF100472, a newly discovered dinucleotide repeat polymorphism [(CA)8 to (CA)15] in the C3 promoter region showed significant association after Bonferroni correction, in the subgroup of MTLE patients having a personal history of FS (MTLE-FS+). Replication analysis in independent patients and controls confirmed that the rare HAP4 haplotype comprising the minimal length allele of GF100472 [(CA)8], protected against MTLE-FS+. A fifth haplotype (HAP5) with medium-size (CA)11 allele of GF100472 displayed four times higher frequency in controls than in the first cohort of MTLE-FS+ and showed a protective effect against FS through a high statistical significance in an independent population of 97 pure FS. Consistently, (CA)11 allele by its own protected against pure FS in a second group of 148 FS patients. Reporter gene assays showed that GF100472 significantly influenced C3 promoter activity (the higher the number of repeats, the lower the transcriptional activity). Taken together, the consistent genetic data and the functional analysis presented here indicate that a newly-identified and functional polymorphism in the promoter of the complement C3 gene might participate in the genetic susceptibility to human MTLE with a history of FS, and to pure FS. Conclusions/Significance The present study provides important data

  5. Increased Immunogenicity and Induction of Class Switching by Conjugation of Complement C3d to Pneumococcal Serotype 14 Capsular Polysaccharide

    PubMed Central

    Test, Samuel T.; Mitsuyoshi, Joyce; Connolly, Charles C.; Lucas, Alexander H.

    2001-01-01

    Previous studies have demonstrated an adjuvant effect for the C3d fragment of complement C3 when coupled to T-dependent protein antigens. In this study, we examined the antibody response to covalent conjugates of C3d and a T-independent antigen, the capsular polysaccharide of serotype 14 Streptococcus pneumoniae (PPS14). We prepared a conjugate of mouse C3d and PPS14 and compared its immunogenicity with that of a conjugate of PPS14 and ovalbumin (OVA). When BALB/c mice were immunized with PPS14-C3d, there was a significant increase in serum anti-PPS14 concentrations compared with either native PPS14 or control PPS14-glycine conjugates. This was accompanied by a switch in anti-PPS14 from predominantly immunoglobulin M (IgM) to IgG1 by day 25 following primary immunization. Following secondary immunization with PPS14-C3d, there was a marked booster response and a further increase in the ratio of IgG1 to IgM anti-PPS14. Although the primary antibody response to the PPS14-OVA conjugate exceeded that induced by immunization with PPS14-C3d, serum anti-PPS14 concentrations after a second injection of PPS14-C3d were nearly identical to those induced by secondary immunization with PPS14-OVA. Experiments with athymic nude mice suggested that T cells were not required for the adjuvant effect of C3d on the primary immune response to PPS14 but were necessary for enhancement of the memory response after a second injection of PPS14-C3d. These studies show that the adjuvant effects of C3d extend to T-independent antigens as well as T-dependent antigens. As a means of harnessing the adjuvant potential of the innate immune system, C3d conjugates may prove useful as a component of vaccines against encapsulated bacteria. PMID:11292721

  6. Increased immunogenicity and induction of class switching by conjugation of complement C3d to pneumococcal serotype 14 capsular polysaccharide.

    PubMed

    Test, S T; Mitsuyoshi, J; Connolly, C C; Lucas, A H

    2001-05-01

    Previous studies have demonstrated an adjuvant effect for the C3d fragment of complement C3 when coupled to T-dependent protein antigens. In this study, we examined the antibody response to covalent conjugates of C3d and a T-independent antigen, the capsular polysaccharide of serotype 14 Streptococcus pneumoniae (PPS14). We prepared a conjugate of mouse C3d and PPS14 and compared its immunogenicity with that of a conjugate of PPS14 and ovalbumin (OVA). When BALB/c mice were immunized with PPS14-C3d, there was a significant increase in serum anti-PPS14 concentrations compared with either native PPS14 or control PPS14-glycine conjugates. This was accompanied by a switch in anti-PPS14 from predominantly immunoglobulin M (IgM) to IgG1 by day 25 following primary immunization. Following secondary immunization with PPS14-C3d, there was a marked booster response and a further increase in the ratio of IgG1 to IgM anti-PPS14. Although the primary antibody response to the PPS14-OVA conjugate exceeded that induced by immunization with PPS14-C3d, serum anti-PPS14 concentrations after a second injection of PPS14-C3d were nearly identical to those induced by secondary immunization with PPS14-OVA. Experiments with athymic nude mice suggested that T cells were not required for the adjuvant effect of C3d on the primary immune response to PPS14 but were necessary for enhancement of the memory response after a second injection of PPS14-C3d. These studies show that the adjuvant effects of C3d extend to T-independent antigens as well as T-dependent antigens. As a means of harnessing the adjuvant potential of the innate immune system, C3d conjugates may prove useful as a component of vaccines against encapsulated bacteria. PMID:11292721

  7. Complement Evasion by Borrelia burgdorferi: Serum-Resistant Strains Promote C3b Inactivation

    PubMed Central

    Alitalo, Antti; Meri, Taru; Rämö, Lasse; Jokiranta, T. Sakari; Heikkilä, Tero; Seppälä, Ilkka J. T.; Oksi, Jarmo; Viljanen, Matti; Meri, Seppo

    2001-01-01

    The most characteristic features of the Lyme disease pathogens, the Borrelia burgdorferi sensu lato (s.l.) group, are their ability to invade tissues and to circumvent the immune defenses of the host for extended periods of time, despite elevated levels of borrelia-specific antibodies in serum and other body fluids. Our aim in the present study was to determine whether B. burgdorferi is able to interfere with complement (C) at the level of C3 by accelerating C3b inactivation and thus to inhibit the amplification of the C cascade. Strains belonging to different genospecies (Borrelia garinii, B. burgdorferi sensu stricto, and Borrelia afzelii) were compared for their sensitivities to normal human serum and abilities to promote factor I-mediated C3b degradation. B. burgdorferi sensu stricto and B. afzelii strains were found to be serum resistant. When the spirochetes were incubated with radiolabeled C3b, factor I-mediated degradation of C3b was observed in the presence of C-resistant B. afzelii (n = 3) and B. burgdorferi sensu stricto (n = 1) strains but not in the presence of C-sensitive B. garinii (n = 7) strains or control bacteria (Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis). Immunoblotting and radioligand binding analyses showed that the C-resistant strains had the capacity to acquire the C inhibitors factor H and factor H-like protein 1 (FHL-1) from growth medium and human serum. A novel surface protein with an apparent molecular mass of 35 kDa was found to preferentially bind to the N terminus region of factor H. Thus, the serum-resistant B. burgdorferi s.l. strains can circumvent C attack by binding the C inhibitors factor H and FHL-1 to their surfaces and promoting factor I-mediated C3b degradation. PMID:11349031

  8. In vitro and in vivo downregulation of C3 by lipoteichoic acid isolated from Lactobacillus plantarum K8 suppressed cytokine-mediated complement system activation.

    PubMed

    Jeon, Boram; Kim, Hye Rim; Kim, Hangeun; Chung, Dae Kyun

    2016-07-01

    Complement component 3 (C3) is one of the proteins associated with complement cascades. C3 plays an essential role in three different pathways-the alternative, classical and lectin pathways. It is well known that cytokines activate complement system and increase complement component C3 production. In the current study, we found that lipoteichoic acid isolated from Lactobacillus plantarum K8 (pLTA) inhibited tumor necrosis factor-alpha (TNF-α) or interferon-gamma (IFN-γ)-mediated C3 mRNA and protein expression in HaCaT cells. pLTA inhibited C3 expression through the inhibition of the phosphorylation of p65 and p38 in the TNF-α-treated cells, while the inhibition of STAT1/2 and JAK2 phosphorylation by pLTA contributed to the reduction of C3 in IFN-γ-treated cells. When mice were pre-injected with pLTA followed by re-injection of TNF-α, serum C3 level was decreased as compared to TNF-α-injected only. Further studies revealed that membrane attack complex (MAC) increased by TNF-α injection was lessened in pLTA-pre-injected mice. A bactericidal assay using mouse sera showed that MAC activity in pLTA-pre-injected mice was lower than in TNF-α only-injected mice. These results suggest that pLTA can suppress inflammatory cytokine-mediated complement activation through the inhibition of C3 synthesis. pLTA application has the potential to alleviate complement-mediated diseases caused by excessive inflammation. PMID:27231239

  9. Modified Low Density Lipoprotein Stimulates Complement C3 Expression and Secretion via Liver X Receptor and Toll-like Receptor 4 Activation in Human Macrophages*

    PubMed Central

    Mogilenko, Denis A.; Kudriavtsev, Igor V.; Trulioff, Andrey S.; Shavva, Vladimir S.; Dizhe, Ella B.; Missyul, Boris V.; Zhakhov, Alexander V.; Ischenko, Alexander M.; Perevozchikov, Andrej P.; Orlov, Sergey V.

    2012-01-01

    Complement C3 is a pivotal component of three cascades of complement activation. C3 is expressed in human atherosclerotic lesions and is involved in atherogenesis. However, the mechanism of C3 accumulation in atherosclerotic lesions is not well elucidated. We show that acetylated low density lipoprotein and oxidized low density lipoprotein (oxLDL) increase C3 gene expression and protein secretion by human macrophages. Modified LDL (mLDL)-mediated activation of C3 expression mainly depends on liver X receptor (LXR) and partly on Toll-like receptor 4 (TLR4), whereas C3 secretion is increased due to TLR4 activation by mLDL. LXR agonist TO901317 stimulates C3 gene expression in human monocyte-macrophage cells but not in human hepatoma (HepG2) cells. We find LXR-responsive element inside of the promoter region of the human C3 gene, which binds to LXRβ in macrophages but not in HepG2 cells. We show that C3 expression and secretion is decreased in IL-4-treated (M2) and increased in IFNγ/LPS-stimulated (M1) human macrophages as compared with resting macrophages. LXR agonist TO901317 potentiates LPS-induced C3 gene expression and protein secretion in macrophages, whereas oxLDL differently modulates LPS-mediated regulation of C3 in M1 or M2 macrophages. Treatment of human macrophages with anaphylatoxin C3a results in stimulation of C3 transcription and secretion as well as increased oxLDL accumulation and augmented oxLDL-mediated up-regulation of the C3 gene. These data provide a novel mechanism of C3 gene regulation in macrophages and suggest new aspects of cross-talk between mLDL, C3, C3a, and TLR4 during development of atherosclerotic lesions. PMID:22194611

  10. Complement anaphylatoxin C3a is a potent inducer of embryonic chick retina regeneration.

    PubMed

    Haynes, Tracy; Luz-Madrigal, Agustin; Reis, Edimara S; Echeverri Ruiz, Nancy P; Grajales-Esquivel, Erika; Tzekou, Apostolia; Tsonis, Panagiotis A; Lambris, John D; Del Rio-Tsonis, Katia

    2013-01-01

    Identifying the initiation signals for tissue regeneration in vertebrates is one of the major challenges in regenerative biology. Much of the research thus far has indicated that certain growth factors have key roles. Here we show that complement fragment C3a is sufficient to induce complete regeneration of the embryonic chick retina from stem/progenitor cells present in the eye, independent of fibroblast growth factor receptor signaling. Instead, C3a induces retina regeneration via STAT3 activation, which in turn activates the injury- and inflammation-responsive factors, IL-6, IL-8 and TNF-α. This activation sets forth regulation of Wnt2b, Six3 and Sox2, genes associated with retina stem and progenitor cells. Thus, our results establish a mechanism for retina regeneration based on injury and inflammation signals. Furthermore, our results indicate a unique function for complement anaphylatoxins that implicate these molecules in the induction and complete regeneration of the retina, opening new avenues of experimentation in the field. PMID:23942241

  11. The internal thioester and the covalent binding properties of the complement proteins C3 and C4.

    PubMed Central

    Law, S. K.; Dodds, A. W.

    1997-01-01

    The covalent binding of complement components C3 and C4 is critical for their activities. This reaction is made possible by the presence of an internal thioester in the native protein. Upon activation, which involves a conformational change initiated by the cleavage of a single peptide bond, the thioester becomes available to react with molecules with nucleophilic groups. This description is probably sufficient to account for the binding of the C4A isotype of human C4 to amino nucleophiles. The binding of the C4B isotype, and most likely C3, to hydroxyl nucleophiles, however, involves a histidine residue, which attacks the thioester to form an intramolecular acyl-imidazole bond. The released thiolate anion then acts as a base to catalyze the binding of hydroxyl nucleophiles, including water, to the acyl function. This mechanism allows the complement proteins to bind to the hydroxyl groups of carbohydrates found on all biological surfaces, including the components of bacterial cell walls. In addition, the fast hydrolysis of the thioester provides a means to contain this very damaging reaction to the immediate proximity of the site of activation. PMID:9041627

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

    PubMed

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

    2016-08-01

    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

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

    PubMed Central

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

    2016-01-01

    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

  14. Identification and molecular characterization of a complement C3 molecule in a lophotrochozoan, the Hawaiian bobtail squid Euprymna scolopes

    PubMed Central

    Castillo, Maria G.; Goodson, Michael S.; McFall-Ngai, Margaret

    2008-01-01

    Examination of the EST database of the light organ of the Hawaiian bobtail squid Euprymna scolopes revealed a sequence with similarity to complement C3. RACE yielded the full open reading frame of this protein. Analysis of the resultant sequence revealed that Es-C3 (E. scolopes-C3) has conserved residues and domains known to be critical for C3 function. The gene encoding C3 was expressed in all tissues tested, indicating that its expression is widely distributed throughout the animal’s body. Immunocytochemistry using an antibody against Es-C3 revealed that the protein is produced principally in the apical surfaces of epithelial cells. The finding of the gene encoding C3 in this mollusk extends the occurrence of this molecule to the lophotrochozoans, demonstrating that complement genes occur in all major branches of the animal kingdom. PMID:18765250

  15. Kinetic analysis of the interactions of complement receptor 2 (CR2, CD21) with its ligands C3d, iC3b, and the EBV glycoprotein gp350/220.

    PubMed

    Sarrias, M R; Franchini, S; Canziani, G; Argyropoulos, E; Moore, W T; Sahu, A; Lambris, J D

    2001-08-01

    The molecular mechanisms involved in the interaction of complement receptor 2 (CR2) with its natural ligands iC3b and C3d are still not well understood. In addition, studies regarding the binding site(s) of the receptor on C3 as well as the affinities of the C3 fragments for CR2 have produced contradictory results. In the present study, we have used surface plasmon resonance technology to study the interaction of CR2 with its ligands C3d, iC3b, and the EBV surface glycoprotein gp350/220. We measured the kinetics of binding of the receptor to its ligands, examined the influence of ionic contacts on these interactions, and assessed whether immobilized and soluble iC3b bound with similar kinetics to CR2. Our results indicate that 1) gp350 binding to CR2 follows a simple 1:1 interaction, whereas that of the C3 fragments is more complex and involves more than one intramolecular component; 2) kinetic differences exist between the binding of C3d and iC3b to CR2, which may be due to an additional binding site found on the C3c region of iC3b; and 3) iC3b binds to CR2 with different kinetics, depending on whether the iC3b is in solution or immobilized on the surface. These findings suggest that binding of CR2 to iC3b and C3d is more complex than previously thought. PMID:11466369

  16. The molecular and structural bases for the association of complement C3 mutations with atypical hemolytic uremic syndrome

    PubMed Central

    Martínez-Barricarte, Rubén; Heurich, Meike; López-Perrote, Andrés; Tortajada, Agustin; Pinto, Sheila; López-Trascasa, Margarita; Sánchez-Corral, Pilar; Morgan, B. Paul; Llorca, Oscar; Harris, Claire L.; Rodríguez de Córdoba, Santiago

    2015-01-01

    Atypical hemolytic uremic syndrome (aHUS) associates with complement dysregulation caused by mutations and polymorphisms in complement activators and regulators. However, the reasons why some mutations in complement proteins predispose to aHUS are poorly understood. Here, we have investigated the functional consequences of three aHUS-associated mutations in C3, R592W, R161W and I1157T. First, we provide evidence that penetrance and disease severity for these mutations is modulated by inheritance of documented “risk” haplotypes as has been observed with mutations in other complement genes. Next, we show that all three mutations markedly reduce the efficiency of factor I-mediated C3b cleavage when catalyzed by membrane cofactor protein (MCP), but not when catalyzed by factor H. Biacore analysis showed that each mutant C3b bound sMCP (recombinant soluble MCP; CD46) at reduced affinity, providing a molecular basis for its reduced cofactor activity. Lastly, we show by electron microscopy structural analysis a displacement of the TED domain from the MG ring in C3b in two of the C3 mutants that explains these defects in regulation. As a whole our data suggest that aHUS-associated mutations in C3 selectively affect regulation of complement on surfaces and provide a structural framework to predict the functional consequences of the C3 genetic variants found in patients. PMID:25879158

  17. Local and systemic activation of the whole complement cascade in human leukocytoclastic cutaneous vasculitis; C3d,g and terminal complement complex as sensitive markers.

    PubMed Central

    Dauchel, H; Joly, P; Delpech, A; Thomine, E; Sauger, F; Le Loet, X; Lauret, P; Tron, F; Fontaine, M; Ripoche, J

    1993-01-01

    We have studied complement activation both in plasma samples and in lesional skin from patients with leukocytoclastic cutaneous vasculitis (LCV). Enzyme immunoassay (EIA) quantification of the complement activation markers, C3d,g and the terminal complement complex (TCC) in plasma, showed that their levels were significantly increased in 66% and 55% of the patients, respectively (n = 29) compared with healthy controls, whereas the standard measurements of C3, factor B, C1q, C4 and C2 were generally within normal range. Elevations of C3d,g and TCC levels in plasma were significantly correlated. Importantly, a significant correlation was found between the severity of the vasculitis and both C3d,g and TCC plasma levels. Immunofluorescence studies of skin biopsy specimens demonstrated simultaneous presence of perivascular dermal deposits of C3d,g and TCC in lesional skin from 96% and 80% respectively of the patients (n = 25). There was a significant correlation between the intensity of the deposits of both markers. Clusterin, a TCC inhibitory protein, was always found at the same sites of perivascular TCC deposits. Immunofluorescence studies at the epidermal basement membrane zone (BMZ) revealed in each case deposits of C3d,g which were accompanied by TCC deposits in 52% of the biopsy specimens. These data demonstrate that there is a local and systemic activation of the whole complement cascade in human LCV. The presence of both C3d,g and clusterin-associated TCC perivascular deposits suggests an intervention of a regulatory mechanism of local complement activation in LCV. Finally, measurement of plasma C3d,g and TCC appears to be a sensitive indicator of systemic complement activation and disease severity in LCV. Images Fig. 1 Fig. 2 PMID:8485913

  18. Intravenous and standard immune serum globulin preparations interfere with uptake of /sup 125/I-C3 onto sensitized erythrocytes and inhibit hemolytic complement activity

    SciTech Connect

    Berger, M.; Rosenkranz, P.; Brown, C.Y.

    1985-02-01

    Antibody-sensitized sheep erythrocytes were used as a model to determine the effects of therapeutic immune serum globulin (ISG) preparations on the ability of this particulate activator to fix C3 and initiate hemolysis. Both standard and intravenous forms of ISG inhibit uptake of /sup 125/I-C3, presumably by competing for the deposition of ''nascent'' C3b molecules onto the erythrocytes. Both forms of ISG also inhibit hemolytic activity of whole serum or purified complement components. The inhibition appears to be a specific property of IgG itself, since similar inhibition was not caused by equivalent concentrations of human serum albumin, and was not affected by the buffer in which the ISG was dissolved. Interference with C3 uptake onto antibody-sensitized platelets and/or inhibition of hemolytic complement activity could contribute to the efficacy of high dose intravenous ISG in idiopathic thrombocytopenic purpura.

  19. Intravenously applied IgG stimulates complement attenuation in a complement-dependent autoimmune disease at the amplifying C3 convertase level.

    PubMed

    Lutz, Hans U; Stammler, Pia; Bianchi, Valentina; Trüeb, Ralph M; Hunziker, Thomas; Burger, Reinhard; Jelezarova, Emiliana; Späth, Peter J

    2004-01-15

    Intravenously applied normal human immunoglobulin G (IgG) has anti-inflammatory effects in the treatment of autoimmune diseases. Systemic inflammation can originate from an overreacting amplification loop of the complement system. In blood, C3b2-containing complexes maintain complement amplification much better than the extremely short-lived C3b. Therefore, in patients with the complement-dependent autoimmune disease, dermatomyositis, we studied whether intravenously applied normal human IgG (IVIG) stimulated in vivo inactivation of these complexes. In the course of IVIG treatment, clinically effective in 6 of 8 patients, the concentration of C3b2-containing complexes dropped to 37% +/- 14% (n = 6) of the pretreatment level when having infused 0.5 g IgG/kg body weight, increased marginally and in parallel to factor Bb thereafter until full-dose IgG was infused. By day 14 following infusion of 2 g IgG/kg body weight the concentration of C3b2-containing complexes was 66% +/- 19%. The plasma concentration of C3 remained constant in myopathic or increased by 15% to 20% in amyopathic patients. In contrast to this, IVIG infusion was associated with consumption of up to 40% of plasma C4 at day 1 to 2 after completion of IVIG infusion. Thus, IVIG had an immediate and long-lasting attenuating effect on complement amplification in vivo, despite the fact that it induced classical complement pathway activation. PMID:14512320

  20. Structural Basis for the Function of Complement Component C4 within the Classical and Lectin Pathways of Complement.

    PubMed

    Mortensen, Sofia; Kidmose, Rune T; Petersen, Steen V; Szilágyi, Ágnes; Prohászka, Zoltan; Andersen, Gregers R

    2015-06-01

    Complement component C4 is a central protein in the classical and lectin pathways within the complement system. During activation of complement, its major fragment C4b becomes covalently attached to the surface of pathogens and altered self-tissue, where it acts as an opsonin marking the surface for removal. Moreover, C4b provides a platform for assembly of the proteolytically active convertases that mediate downstream complement activation by cleavage of C3 and C5. In this article, we present the crystal and solution structures of the 195-kDa C4b. Our results provide the molecular details of the rearrangement accompanying C4 cleavage and suggest intramolecular flexibility of C4b. The conformations of C4b and its paralogue C3b are shown to be remarkably conserved, suggesting that the convertases from the classical and alternative pathways are likely to share their overall architecture and mode of substrate recognition. We propose an overall molecular model for the classical pathway C5 convertase in complex with C5, suggesting that C3b increases the affinity for the substrate by inducing conformational changes in C4b rather than a direct interaction with C5. C4b-specific features revealed by our structural studies are probably involved in the assembly of the classical pathway C3/C5 convertases and C4b binding to regulators. PMID:25911760

  1. Human C3 mutation reveals a mechanism of dense deposit disease pathogenesis and provides insights into complement activation and regulation

    PubMed Central

    Martínez-Barricarte, Rubén; Heurich, Meike; Valdes-Cañedo, Francisco; Vazquez-Martul, Eduardo; Torreira, Eva; Montes, Tamara; Tortajada, Agustín; Pinto, Sheila; Lopez-Trascasa, Margarita; Morgan, B. Paul; Llorca, Oscar; Harris, Claire L.; Rodríguez de Córdoba, Santiago

    2010-01-01

    Dense deposit disease (DDD) is a severe renal disease characterized by accumulation of electron-dense material in the mesangium and glomerular basement membrane. Previously, DDD has been associated with deficiency of factor H (fH), a plasma regulator of the alternative pathway (AP) of complement activation, and studies in animal models have linked pathogenesis to the massive complement factor 3 (C3) activation caused by this deficiency. Here, we identified a unique DDD pedigree that associates disease with a mutation in the C3 gene. Mutant C3923ΔDG, which lacks 2 amino acids, could not be cleaved to C3b by the AP C3-convertase and was therefore the predominant circulating C3 protein in the patients. However, upon activation to C3b by proteases, or to C3(H2O) by spontaneous thioester hydrolysis, C3923ΔDG generated an active AP C3-convertase that was regulated normally by decay accelerating factor (DAF) but was resistant to decay by fH. Moreover, activated C3b923ΔDG and C3(H2O)923ΔDG were resistant to proteolysis by factor I (fI) in the presence of fH, but were efficiently inactivated in the presence of membrane cofactor protein (MCP). These characteristics cause a fluid phase–restricted AP dysregulation in the patients that continuously activated and consumed C3 produced by the normal C3 allele. These findings expose structural requirements in C3 that are critical for recognition of the substrate C3 by the AP C3-convertase and for the regulatory activities of fH, DAF, and MCP, all of which have implications for therapeutic developments. PMID:20852386

  2. Low Serum Complement C3 Levels at Diagnosis of Renal ANCA-Associated Vasculitis Is Associated with Poor Prognosis

    PubMed Central

    Augusto, Jean-François; Langs, Virginie; Demiselle, Julien; Lavigne, Christian; Brilland, Benoit; Duveau, Agnès; Poli, Caroline; Chevailler, Alain; Croue, Anne; Tollis, Frederic; Sayegh, Johnny; Subra, Jean-François

    2016-01-01

    Background Recent studies have demonstrated the key role of the complement alternative pathway (cAP) in the pathophysiology of experimental ANCA-associated vasculitis (AAV). However, in human AAV the role of cAP has not been extensively explored. In the present work, we analysed circulating serum C3 levels measured at AAV onset and their relation to outcomes. Methods We conducted a retrospective observational cohort study including 45 consecutive patients with AAV diagnosed between 2000 and 2014 with serum C3 measurement at diagnosis, before immunosuppressive treatment initiation. Two groups were defined according to the median serum C3 level value: the low C3 group (C3<120 mg/dL) and the high C3 level group (C3≥120 mg/dL). Patient and renal survivals, association between C3 level and renal pathology were analysed. Results Serum complement C3 concentration remained in the normal range [78–184 mg/dL]. Compared with the high C3 level, the patients in the low C3 level group had lower complement C4 concentrations (P = 0.008) and lower eGFR (P = 0.002) at diagnosis. The low C3 level group had poorer patient and death-censored renal survivals, compared with the high C3 level group (P = 0.047 and P = 0.001, respectively). We observed a significant negative correlation between C3 levels and the percentage of glomeruli affected by cellular crescent (P = 0.017, r = -0.407). According to the Berden et al renal histologic classification, patients in the crescentic/mixed category had low C3 levels more frequently (P<0.01). Interestingly, we observed that when patients with the crescentic/mixed histologic form were analysed according to C3 level, long term renal survival was significantly greater in the high C3 level group than in the low C3 level group (100% vs 40.7% at 6 years, p = 0.046). No relationship between serum C4 and renal outcome was observed. Conclusion A Low C3 serum level in AAV patients at diagnosis is associated with worse long-term patient and renal

  3. Derivation of ligands for the complement C3a receptor from the C-terminus of C5a

    PubMed Central

    Halai, Reena; Bellows-Peterson, Meghan L; Branchett, Will; Smadbeck, James; Kieslich, Chris A; Croker, Daniel E; Cooper, Matthew A; Morikis, Dimitrios; Woodruff, Trent M; Floudas, Christodoulos A; Monk, Peter N

    2014-01-01

    The complement cascade is a highly sophisticated network of proteins that are well regulated and directed in response to invading pathogens or tissue injury. Complement C3a and C5a are key mediators produced by this cascade, and their dysregulation has been linked to a plethora of inflammatory and autoimmune diseases. Consequently, this has stimulated interest in the development of ligands for the receptors for these complement peptides, C3a receptor, and C5a1 (C5aR/CD88). In this study we used computational methods to design novel C5a1 receptor ligands. However, functional screening in human monocyte-derived macrophages using the xCELLigence label-free platform demonstrated altered specificity of our ligands. No agonist/antagonist activity was observed at C5a1, but we instead saw that the ligands were able to partially agonize the closely related complement receptor C3a receptor. This was verified in the presence of C3a receptor antagonist SB 290157 and in a stable cell line expressing either C5a1 or C3a receptor alone. C3a agonism has been suggested to be a potential treatment of acute neutrophil-driven traumatic pathologies, and may have great potential as a therapeutic avenue in this arena. PMID:25446428

  4. HIV-1 induces complement factor C3 synthesis in astrocytes and neurons by modulation of promoter activity.

    PubMed

    Bruder, Cornelia; Hagleitner, Magdalena; Darlington, Gretchen; Mohsenipour, Iradj; Würzner, Reinhard; Höllmüller, Isolde; Stoiber, Heribert; Lass-Flörl, Cornelia; Dierich, Manfred P; Speth, Cornelia

    2004-02-01

    Virus-induced complement expression and activation in the brain is hypothesized to contribute to the process of neurodegeneration in AIDS-associated neurological disorders. Previous experiments have shown that the human immunodeficiency virus (HIV) upregulates the low basal production of complement factor C3 in astrocytes and neurons. Since inhibition of complement synthesis and activation in the brain may represent a putative therapeutic goal to prevent virus-induced damage, we analysed the mechanism of the HIV-induced modulation of C3 expression. Detailed studies using different C3 promoter constructs revealed that HIV activates the synthesis of C3 by stimulation of the promoter. This HIV-induced promoter activation could be measured both in different astrocytic cell lines and in neurons. Deletion constructs of the C3 promoter defined the IL-6/IL-1beta responsive element within the promoter region as a central element for the responsiveness of the C3 promoter towards the influence of HIV. A binding site for the transcription factor C/EBPdelta was identified as important regulatory domain within the IL-6/IL-1beta responsive element, since a point mutation which eliminates the binding capacity of C/EBPdelta to this site also abolishes the induction by HIV-1. Similarly, the viral proteins Nef and gp41 which had also been shown to stimulate the synthesis of C3, exert their effect via the IL-6/IL-1beta responsive element with binding of the transcription factor C/EBPdelta representing the critical step. Our experiments clearly define the mechanism for the induction of complement factors in the HIV-infected brain and reveal a decisive role of the regulator protein C/EBPdelta for the HIV-induced increase in C3 expression. PMID:14725791

  5. Genetics Home Reference: complement component 2 deficiency

    MedlinePlus

    ... Page Jönsson G, Sjöholm AG, Truedsson L, Bengtsson AA, Braconier JH, Sturfelt G. Rheumatological manifestations, organ damage ... 31. Review. Citation on PubMed Truedsson L, Bengtsson AA, Sturfelt G. Complement deficiencies and systemic lupus erythematosus. ...

  6. Molecular characterization and expression analysis of a complement component 3 in the sea cucumber (Apostichopus japonicus).

    PubMed

    Zhou, Zunchun; Sun, Dapeng; Yang, Aifu; Dong, Ying; Chen, Zhong; Wang, Xiaoyu; Guan, Xiaoyan; Jiang, Bei; Wang, Bai

    2011-10-01

    The complement system has been discovered in invertebrates and vertebrates, and plays a crucial role in the innate defense against common pathogens. As a central component in the complement system, complement component 3 (C3) is an intermediary between innate and adaptive immune system. In this study, a new isoform of C3 in the sea cucumber Apostichopus japonicus, termed AjC3-2 was identified. Its open reading frame (ORF) is 5085 bp and encodes for 1695 amino acids with a putative signal peptide of 20 amino acid residues. The mature protein molecular weight of AjC3-2 was 187.72 kDa. It has a conserved thioester site and a linker R(689)RRR(692) where AjC3-2 is splitted into β and α chain during posttranslational modification. The expression patterns of two distinct sea cucumber C3 genes, AjC3-2 and AjC3, were similar. During the different development stages from unfertilized egg to juvenile of the sea cucumber, the highest expression levels of AjC3-2 and AjC3 genes were both found in late auricularia. In the adult, the highest expression of these two genes was observed in the coelomocytes and followed by the body wall. AjC3-2 and AjC3 genes expression increased significantly at 6 h after the LPS challenge. These results indicated that these two C3 genes play a pivotal role in immune responses to the bacterial infection in sea cucumber. PMID:21752342

  7. Clumping Factor A Interaction with Complement Factor I Increases C3b Cleavage on the Bacterial Surface of Staphylococcus aureus and Decreases Complement-Mediated Phagocytosis▿

    PubMed Central

    Hair, Pamela S.; Echague, Charlene G.; Sholl, Amber M.; Watkins, Justin A.; Geoghegan, Joan A.; Foster, Timothy J.; Cunnion, Kenji M.

    2010-01-01

    The human complement system is important in the immunological control of Staphylococcus aureus infection. We showed previously that S. aureus surface protein clumping factor A (ClfA), when expressed in recombinant form, bound complement control protein factor I and increased factor I cleavage of C3b to iC3b. In the present study, we show that, compared to the results for the wild type, when isogenic ClfA-deficient S. aureus mutants were incubated in serum, they bound less factor I, generated less iC3b on the bacterial surface, and bound fewer C3 fragments. It has been shown previously that two amino acids in ClfA (P336 and Y338) are essential for fibrinogen binding. However, S. aureus expressing ClfA(P336A Y338S) was less virulent than ClfA-deficient strains in animal models. This suggested that ClfA contributed to S. aureus virulence by a mechanism different than fibrinogen binding. In the present study, we showed that S. aureus expressing ClfA(P336A Y338S) was more susceptible to complement-mediated phagocytosis than a ClfA-null mutant or the wild type. Unlike ClfA, ClfA(P336A Y338S) did not enhance factor I cleavage of C3b to iC3b and inhibited the cofactor function of factor H. Fibrinogen enhanced factor I binding to ClfA and the S. aureus surface. Twenty clinical S. aureus strains all expressed ClfA and bound factor I. High levels of factor I binding by clinical strains correlated with poor phagocytosis. In summary, our results suggest that the interaction of ClfA with factor I contributes to S. aureus virulence by a complement-mediated mechanism. PMID:20100856

  8. Targeting complement component 5a promotes vascular integrity and limits airway remodeling.

    PubMed

    Khan, Mohammad A; Maasch, Christian; Vater, Axel; Klussmann, Sven; Morser, John; Leung, Lawrence L; Atkinson, Carl; Tomlinson, Stephen; Heeger, Peter S; Nicolls, Mark R

    2013-04-01

    Increased microvascular dilatation and permeability is observed during allograft rejection. Because vascular integrity is an important indicator of transplant health, we have sought to limit injury to blood vessels by blocking complement activation. Although complement component 3 (C3) inhibition is known to be vasculoprotective in transplantation studies, we recently demonstrated the paradoxical finding that, early in rejection, C3(-/-) transplant recipients actually exhibit worse microvascular injury than controls. In the genetic absence of C3, thrombin-mediated complement component 5 (C5) convertase activity leads to the generation of C5a (anaphylatoxin), a promoter of vasodilatation and permeability. In the current study, we demonstrated that microvessel thrombin deposition is significantly increased in C3(-/-) recipients during acute rejection. Thrombin colocalization with microvessels is closely associated with remarkably elevated plasma levels of C5a, vasodilatation, and increased vascular permeability. Administration of NOX-D19, a specific C5a inhibitor, to C3(-/-) recipients of airway transplants significantly improved tissue oxygenation, limited microvascular leakiness, and prevented airway ischemia, even in the absence of conventional T-cell-directed immunosuppression. As C3 inhibitors enter the clinics, the simultaneous targeting of this thrombin-mediated complement activation pathway and/or C5a itself may confer significant clinical benefit. PMID:23530212

  9. Differential effects of complement activation products c3a and c5a on cardiovascular function in hypertensive pregnant rats.

    PubMed

    Lillegard, Kathryn E; Loeks-Johnson, Alex C; Opacich, Jonathan W; Peterson, Jenna M; Bauer, Ashley J; Elmquist, Barbara J; Regal, Ronald R; Gilbert, Jeffrey S; Regal, Jean F

    2014-11-01

    Early-onset pre-eclampsia is characterized by decreased placental perfusion, new-onset hypertension, angiogenic imbalance, and endothelial dysfunction associated with excessive activation of the innate immune complement system. Although our previous studies demonstrated that inhibition of complement activation attenuates placental ischemia-induced hypertension using the rat reduced uterine perfusion pressure (RUPP) model, the important product(s) of complement activation has yet to be identified. We hypothesized that antagonism of receptors for complement activation products C3a and C5a would improve vascular function and attenuate RUPP hypertension. On gestational day (GD) 14, rats underwent sham surgery or vascular clip placement on ovarian arteries and abdominal aorta (RUPP). Rats were treated once daily with the C5a receptor antagonist (C5aRA), PMX51 (acetyl-F-[Orn-P-(D-Cha)-WR]), the C3a receptor antagonist (C3aRA), SB290157 (N(2)-[(2,2-diphenylethoxy)acetyl]-l-arginine), or vehicle from GD 14-18. Both the C3aRA and C5aRA attenuated placental ischemia-induced hypertension without affecting the decreased fetal weight or decreased concentration of free circulating vascular endothelial growth factor (VEGF) also present in this model. The C5aRA, but not the C3aRA, attenuated placental ischemia-induced increase in heart rate and impaired endothelial-dependent relaxation. The C3aRA abrogated the acute pressor response to C3a peptide injection, but it also unexpectedly attenuated the placental ischemia-induced increase in C3a, suggesting nonreceptor-mediated effects. Overall, these results indicate that both C3a and C5a are important products of complement activation that mediate the hypertension regardless of the reduction in free plasma VEGF. The mechanism by which C3a contributes to placental ischemia-induced hypertension appears to be distinct from that of C5a, and management of pregnancy-induced hypertension is likely to require a broad anti

  10. Electrostatic Contributions Drive the Interaction Between Staphylococcus aureus Protein Efb-C and its Complement Target C3d

    SciTech Connect

    Haspel, N.; Ricklin, D.; Geisbrecht, B.V.; Kavraki, L.E.; Lambris, J.D.

    2008-11-13

    The C3-inhibitory domain of Staphylococcus aureus extracellular fibrinogen-binding protein (Efb-C) defines a novel three-helix bundle motif that regulates complement activation. Previous crystallographic studies of Efb-C bound to its cognate subdomain of human C3 (C3d) identified Arg-131 and Asn-138 of Efb-C as key residues for its activity. In order to characterize more completely the physical and chemical driving forces behind this important interaction, we employed in this study a combination of structural, biophysical, and computational methods to analyze the interaction of C3d with Efb-C and the single-point mutants R131A and N138A. Our results show that while these mutations do not drastically affect the structure of the Efb-C/C3d recognition complex, they have significant adverse effects on both the thermodynamic and kinetic profiles of the resulting complexes. We also characterized other key interactions along the Efb-C/C3d binding interface and found an intricate network of salt bridges and hydrogen bonds that anchor Efb-C to C3d, resulting in its potent complement inhibitory properties.

  11. Electrostatic contributions drive the interaction between Staphylococcus aureus protein Efb-C and its complement target C3d

    PubMed Central

    Haspel, Nurit; Ricklin, Daniel; Geisbrecht, Brian V.; Kavraki, Lydia E.; Lambris, John D.

    2008-01-01

    The C3–inhibitory domain of Staphylococcus aureus extracellular fibrinogen-binding protein (Efb-C) defines a novel three-helix bundle motif that regulates complement activation. Previous crystallographic studies of Efb-C bound to its cognate subdomain of human C3 (C3d) identified Arg-131 and Asn-138 of Efb-C as key residues for its activity. In order to characterize more completely the physical and chemical driving forces behind this important interaction, we employed in this study a combination of structural, biophysical, and computational methods to analyze the interaction of C3d with Efb-C and the single-point mutants R131A and N138A. Our results show that while these mutations do not drastically affect the structure of the Efb-C/C3d recognition complex, they have significant adverse effects on both the thermodynamic and kinetic profiles of the resulting complexes. We also characterized other key interactions along the Efb-C/C3d binding interface and found an intricate network of salt bridges and hydrogen bonds that anchor Efb-C to C3d, resulting in its potent complement inhibitory properties. PMID:18687868

  12. The N-terminal segment of glyceraldehyde-3-phosphate dehydrogenase of Haemonchus contortus interacts with complements C1q and C3.

    PubMed

    Vedamurthy, G V; Sahoo, S; Devi, I K; Murugavel, S; Joshi, P

    2015-11-01

    Haemonchus contortus, an economically important blood-sucking parasite of sheep and goats, survives the harsh host gut environment by secreting a number of proteins referred as excretory/secretory (ES) products. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a glycolytic enzyme, is one of the components of H. contortus ES products. The parasite enzyme binds to complement C3 and inhibits its activity. In this study, the C3-binding activity of the parasite GAPDH was mapped to the N-terminal part of the enzyme by generating defined recombinant fragments of the protein. The N-terminal fragment also trapped complement C1q but not C5 and inhibited complement-mediated lysis of sensitized sheep erythrocytes. Competitive binding assay indicates different binding regions for C1q and C3 proteins. GAPDH stimulated proliferation of goat peripheral blood mononuclear cells in vitro and reacted with the sera from H. contortus-infected animals. However, the fragments of GAPDH did not stimulate cell proliferation nor reacted with the infected animal sera. Furthermore, denatured GAPDH failed to react with the infected animal sera in dot blot suggesting conformation-dependent epitope. These results demonstrate an elegant strategy of the parasite to completely shut down complement activation and identify GAPDH as a promising target for future therapeutic intervention. PMID:26332726

  13. S100A8-S100A9 protein complex mediates psoriasis by regulating the expression of complement factor C3.

    PubMed

    Schonthaler, Helia B; Guinea-Viniegra, Juan; Wculek, Stefanie K; Ruppen, Isabel; Ximénez-Embún, Pilar; Guío-Carrión, Ana; Navarro, Raquel; Hogg, Nancy; Ashman, Keith; Wagner, Erwin F

    2013-12-12

    Psoriasis is a common heterogeneous inflammatory skin disease with a complex pathophysiology and limited treatment options. Here we performed proteomic analyses of human psoriatic epidermis and found S100A8-S100A9, also called calprotectin, as the most upregulated proteins, followed by the complement component C3. Both S100A8-S100A9 and C3 are specifically expressed in lesional psoriatic skin. S100A9 is shown here to function as a chromatin component modulating C3 expression in mouse and human cells by binding to a region upstream of the C3 start site. When S100A9 was genetically deleted in mouse models of skin inflammation, the psoriasis-like skin disease and inflammation were strongly attenuated, with a mild immune infiltrate and decreased amounts of C3. In addition, inhibition of C3 in the mouse model strongly reduced the inflammatory skin disease. Thus, S100A8-S100A9 can regulate C3 at the nuclear level and present potential new therapeutic targets for psoriasis. PMID:24332034

  14. Using an in vitro xenoantibody-mediated complement-dependent cytotoxicity model to evaluate the complement inhibitory activity of the peptidic C3 inhibitor Cp40

    PubMed Central

    Wang, Junxiang; Wang, Lu; Xiang, Ying; Ricklin, Daniel; Lambris, John D.; Chen, Gang

    2016-01-01

    Simple and reliable methods for evaluating the inhibitory effects of drug candidates on complement activation are essential for preclinical development. Here, using an immortalized porcine aortic endothelial cell line (iPEC) as target, we evaluated the feasibility and effectiveness of an in vitro xenoantibody-mediated complement-dependent cytotoxicity (CDC) model for evaluating the complement inhibitory activity of Cp40, a potent analog of the peptidic C3 inhibitor compstatin. The binding of human xenoantibodies to iPECs led to serum dilution-dependent cell death. Pretreatment of the human serum with Cp40 almost completely inhibited the deposition of C3 fragments and C5b-9 on the cells, resulting in a dose-dependent inhibition of CDC against the iPECs. Using the same method to compare the effects of Cp40 on complement activation in humans, rhesus and cynomolgus monkeys, we found that the inhibitory patterns were similar overall. Thus, the in vitro xenoantibody-mediated CDC assay may have considerable potential for future clinical use. PMID:26548839

  15. Identification and characterization of complement C3 receptors on human astrocytes.

    PubMed

    Gasque, P; Chan, P; Mauger, C; Schouft, M T; Singhrao, S; Dierich, M P; Morgan, B P; Fontaine, M

    1996-03-15

    Astrocytes express C components and have been implicated as a major source of intrathecal C. To ascertain the effects of C activation on these cells, we have evaluated the expression of CR1, CR2, and CR3 (CD35, CD21, and CD11b/CD18) in primary fetal astrocytes and astrocyte cell lines. None of the astrocyte cells tested expressed CR3, whereas primary astrocytes and one of four astrocyte cell lines expressed CR1 (220 kDa), as assessed at the protein and mRNA level. Primary fetal astrocytes and all four astrocyte cell lines expressed CR2 (155 kDa). Expression of CR2 by astrocytes was confirmed at mRNA level by reverse-transcriptase PCR, using different combinations of seven specific CR2 oligonucleotides, and by partial sequencing of the astrocyte CR2 cDNA. Astrocyte CR2 cDNA presented 100% homology with the lymphocyte CR2 cDNA between the position 181 bp to 600 bp and position 1017 bp to 1347 bp. An alternative splicing pattern of exon 11, reported previously in B cells, was observed in astrocyte CR2 cDNA. Astrocyte CR2 was functional, in that it specifically bound C3d and the EBV surface protein gp340, and the binding was blocked specifically with polyclonal anti-CR2. Scatchard analysis of membrane expression of CR2 on astrocytes revealed 2000 functional sites per cell with a Kd (3 x 10(-7) M) identical with that of CR2 on B cell (Raji). PMID:8690915

  16. Properdin and C3 Proactivator: Alternate Pathway Components in Human Glomerulonephritis

    PubMed Central

    McLean, Robert H.; Michael, Alfred F.

    1973-01-01

    Serological and immunopathological studies of human glomerulonephritis have suggested that alternate pathways of activation of the third component of complement may be important in some forms of glomerulonephritis. We have investigated the role of two alternate pathway proteins, properdin and C3 proactivator, in 22 patients with chronic membranoproliferative glomerulonephritis, 21 patients with systemic lupus erythematosus, 20 patients with acute poststreptococcal glomerulonephritis, and 19 patients with other forms of renal disease. C3 (measured at β1A), properdin, and C3 proactivator were assayed by single radial immunodiffusion. In sera with low β1A (< 2 SD), mean properdin was most significantly decreased in patients with acute poststreptococcal glomerulonephritis but was also significantly decreased in chronic membranoproliferative glomerulonephritis and in untreated systemic lupus erythematosus. Properdin levels in other renal disease, acute glomerulonephritis, and chronic membranoproliferative glomerulonephritis with normal β1A levels were not significantly different from normal. A positive correlation between β1A and properdin levels in individual sera was present in all diseases except systemic lupus erythematosus. Serum C3 proactivator was markedly decreased in active systemic lupus erythematosus and there was a positive correlation between β1A and C3 proactivator levels in systemic lupus erythematosus and other renal diseases but not acute poststreptococcal glomerulonephritis. Properdin in fresh sera from four patients with systemic lupus erythematosus and five with chronic membranoproliferative glomerulonephritis showed increased migration toward the cathode on immunoelectrophoresis, suggesting in vivo change of the properdin molecule. The observation of reduced serum levels of properdin and C3 proactivator and altered electrophoretic migration of properdin in some patients with glomerulonephritis provide new evidence for participation of these

  17. Localization of the expression of complement component 3 in the human endometrium by in situ hybridization

    SciTech Connect

    Sayegh, R.A.; Tao, Xiao Jing; Awwad, J.T.

    1996-04-01

    C3 production by the human endometrium has been previously described. The objective of the current study was to localize the site of expression and regulation of the third component of complement, C3, in the endometrium. Eight secretory and eight proliferative archival endometrial samples from hysterectomy and endometrial biopsy specimens were used for in situ hybridization analysis. This analysis was performed with a radiolabeled riboprobe synthesized from a 736-bp template representing sequence 1944-2680 of the human C3 complementary DNA. Duplicate sections were hybridized with sense and antisense riboprobes. Resultant autoradiograms were analyzed qualitatively by light- and darkfield microscopy. In proliferative endometrium, minimal expression of C3 was observed and was limited to a few stromal patches and glands throughout the section. In the secretory samples, prominent C3 expression was observed in both the glands and stroma of the basalis layer. Endometrial lymphocytes did not express C3. Endometrial stromal and glandular cells express the C3 gene. Endometrial lymphocytes did not express C3, but other nondistinct lymphoid elements scattered in the stroma may be expressing C3. There was a visibly more intense expression of C3 in the basalis layer of the secretory endometrium than in proliferative endometrium. The spatial and temporal pattern of C3 expression may have implications in normal menstrual physiology and in the immunological response of the endometrium to the invading trophoblast during placentation. 23 refs., 4 figs., 1 tab.

  18. Complement Component 3 Is Regulated by TWIST1 and Mediates Epithelial-Mesenchymal Transition.

    PubMed

    Cho, Min Soon; Rupaimoole, Rajesha; Choi, Hyun-Jin; Noh, Kyunghee; Chen, Jichao; Hu, Qianghua; Sood, Anil K; Afshar-Kharghan, Vahid

    2016-02-01

    We have previously shown that complement component 3 (C3) is secreted by malignant epithelial cells. To understand the mechanism of upregulation of C3 expression in tumor cells, we studied the C3 promoter and identified that twist basic helix-loop-helix transcription factor 1 (TWIST1) binds to the C3 promoter and enhances its expression. Because TWIST1 mediates epithelial-mesenchymal transition (EMT), we studied the effect of C3 on EMT and found that C3 decreased E-cadherin expression on cancer cells and promoted EMT. We showed that C3-induced reduction in E-cadherin expression in ovarian cancer cells was mediated by C3a and is Krüppel-like factor 5 dependent. We investigated the association between TWIST1 and C3 in malignant tumors and in murine embryos. TWIST1 and C3 colocalized at the invasive tumor edges, and in the neural crest and limb buds of mouse embryos. Our results identified TWIST1 as a transcription factor that regulates C3 expression during pathologic and physiologic EMT. PMID:26718342

  19. Peptide inhibitors of C3 activation as a novel strategy of complement inhibition for the treatment of paroxysmal nocturnal hemoglobinuria

    PubMed Central

    Ricklin, Daniel; Huang, Yijun; Reis, Edimara S.; Chen, Hui; Ricci, Patrizia; Lin, Zhuoer; Pascariello, Caterina; Raia, Maddalena; Sica, Michela; Del Vecchio, Luigi; Pane, Fabrizio; Lupu, Florea; Notaro, Rosario; Resuello, Ranillo R. G.; DeAngelis, Robert A.; Lambris, John D.

    2014-01-01

    Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by complement-mediated intravascular hemolysis due to the lack of CD55 and CD59 on affected erythrocytes. The anti-C5 antibody eculizumab has proven clinically effective, but uncontrolled C3 activation due to CD55 absence may result in opsonization of erythrocytes, possibly leading to clinically meaningful extravascular hemolysis. We investigated the effect of the peptidic C3 inhibitor, compstatin Cp40, and its long-acting form (polyethylene glycol [PEG]-Cp40) on hemolysis and opsonization of PNH erythrocytes in an established in vitro system. Both compounds demonstrated dose-dependent inhibition of hemolysis with IC50 ∼4 µM and full inhibition at 6 µM. Protective levels of either Cp40 or PEG-Cp40 also efficiently prevented deposition of C3 fragments on PNH erythrocytes. We further explored the potential of both inhibitors for systemic administration and performed pharmacokinetic evaluation in nonhuman primates. A single intravenous injection of PEG-Cp40 resulted in a prolonged elimination half-life of >5 days but may potentially affect the plasma levels of C3. Despite faster elimination kinetics, saturating inhibitor concentration could be reached with unmodified Cp40 through repetitive subcutaneous administration. In conclusion, peptide inhibitors of C3 activation effectively prevent hemolysis and C3 opsonization of PNH erythrocytes, and are excellent, and potentially cost-effective, candidates for further clinical investigation. PMID:24497537

  20. Complement components of nerve regeneration conditioned fluid influence the microenvironment of nerve regeneration

    PubMed Central

    Li, Guang-shuai; Li, Qing-feng; Dong, Ming-min; Zan, Tao; Ding, Shuang; Liu, Lin-bo

    2016-01-01

    Nerve regeneration conditioned fluid is secreted by nerve stumps inside a nerve regeneration chamber. A better understanding of the proteinogram of nerve regeneration conditioned fluid can provide evidence for studying the role of the microenvironment in peripheral nerve regeneration. In this study, we used cylindrical silicone tubes as the nerve regeneration chamber model for the repair of injured rat sciatic nerve. Isobaric tags for relative and absolute quantitation proteomics technology and western blot analysis confirmed that there were more than 10 complement components (complement factor I, C1q-A, C1q-B, C2, C3, C4, C5, C7, C8β and complement factor D) in the nerve regeneration conditioned fluid and each varied at different time points. These findings suggest that all these complement components have a functional role in nerve regeneration. PMID:27212935

  1. Testing the Activity of Complement Convertases in Serum/Plasma for Diagnosis of C4NeF-Mediated C3 Glomerulonephritis.

    PubMed

    Blom, Anna M; Corvillo, Fernando; Magda, Michal; Stasiłojć, Grzegorz; Nozal, Pilar; Pérez-Valdivia, Miguel Ángel; Cabello-Chaves, Virginia; Rodríguez de Córdoba, Santiago; López-Trascasa, Margarita; Okrój, Marcin

    2016-07-01

    Autoantibodies termed C3-nephritic factor (C3NeF), which stabilize convertases of the alternative complement pathway, often stimulate autoinflammatory diseases. However, knowledge about analogous autoantibodies acting on the classical pathway (C4NeF) is limited to a few reports, which indicate association with kidney dysfunction, systemic lupus erythematous, and infections. C4NeF may appear independently from C3NeF, but the lack of a routine diagnostic method predisposes C4NeF for being an underestimated player in autoinflammatory episodes. We tested the activity of classical convertases directly in serum/plasma to screen samples from 13 patients with C3 glomerulopathies and identified one patient showing significantly prolonged half-life of these enzymes. Observed effect was reproduced by immunoglobulins purified from patient's plasma and additionally confirmed on classical convertase built from purified components. Isolated immunoglobulins protected classical convertases from both spontaneous and inhibitor-driven decay but not from C4b proteolysis. The patient had a decreased serum level of C3, elevated sC5b-9, and normal concentrations of factor B and C4. Neither C3NeF nor other autoantibodies directed against alternative pathway proteins (factor H, factor B, factor I, C3, and properdin) were found. Genetic analysis showed no mutations in C3, CFB, CFH, CFI, MCP, THBD, and DGKE genes. Renal biopsy revealed a membranoproliferative pattern with intense C3 deposits. Our results underline the importance of C4NeF as an independent pathogenic factor and a need for the implementation of routine examination of classical convertase activity. Proposed method may enable robust inspection of such atypical cases. PMID:27146825

  2. Deficiency of the Complement Component 3 but Not Factor B Aggravates Staphylococcus aureus Septic Arthritis in Mice.

    PubMed

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

    2016-04-01

    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

  3. Complement in acute and chronic arthritides: assessment of C3c, C9, and protectin (CD59) in synovial membrane.

    PubMed Central

    Konttinen, Y T; Ceponis, A; Meri, S; Vuorikoski, A; Kortekangas, P; Sorsa, T; Sukura, A; Santavirta, S

    1996-01-01

    OBJECTIVES: To investigate the role of complement cascade induced damage and protection against it in acute arthritides compared to rheumatoid arthritis and other chronic joint derangements. METHODS: C3c, C9, and protectin (CD59) were examined by avidin-biotin-peroxidase complex staining. RESULTS: Marked deposits of C3c and C9 were found in synovial vasculature and intercellular matrix of the lining in rheumatoid arthritis and in acute arthritides (including bacterial, reactive, and osteoarthritis flare up). Furthermore, protectin was not visible in synovial lining cells and was relatively weakly expressed in stromal and endothelial cells in rheumatoid arthritis; also in acute arthritides protectin expression was weak. In contrast, C3c and C9 deposits were not found in chronic conditions associated with degenerative diseases (osteoarthritis and osteochondritis dissecans) or mechanical causes (patellar luxation and a ruptured meniscus), in which also the protectin expression was prominent in synovial lining, endothelial and some stromal cells. CONCLUSIONS: Activation of the complement in rheumatoid arthritis and in acute arthritides seems to be associated with a decreased protection of synovial cells against cellular effects and lysis mediated by membrane attack complex. Images PMID:9014582

  4. Genetic Association of the Porcine C9 Complement Component with Hemolytic Complement Activity.

    PubMed

    Khoa, D V A; Wimmers, K

    2015-09-01

    The complement system is a part of the natural immune regulation mechanism against invading pathogens. Complement activation from three different pathways (classical, lectin, and alternative) leads to the formation of C5-convertase, an enzyme for cleavage of C5 into C5a and C5b, followed by C6, C7, C8, and C9 in membrane attack complex. The C9 is the last complement component of the terminal lytic pathway, which plays an important role in lysis of the target cells depending on its self-polymerization to form transmembrane channels. To address the association of C9 with traits related to disease resistance, the complete porcine C9 cDNA was comparatively sequenced to detect single nucleotide polymorphisms (SNPs) in pigs of the breeds Hampshire (HS), Duroc (DU), Berlin miniature pig (BMP), German Landrace (LR), Pietrain (PIE), and Muong Khuong (Vietnamese potbelly pig). Genotyping was performed in 417 F2 animals of a resource population (DUMI: DU×BMP) that were vaccinated with Mycoplasma hyopneumoniae, Aujeszky diseases virus and porcine respiratory and reproductive syndrome virus at 6, 14 and 16 weeks of age, respectively. Two SNPs were detected within the third exon. One of them has an amino acid substitution. The European porcine breeds (LR and PIE) show higher allele frequency of these SNPs than Vietnamese porcine breed (MK). Association of the substitution SNP with hemolytic complement activity indicated statistically significant differences between genotypes in the classical pathway but not in the alternative pathway. The interactions between eight time points of measurement of complement activity before and after vaccinations and genotypes were significantly different. The difference in hemolytic complement activity in the both pathways depends on genotype, kind of vaccine, age and the interaction to the other complement components. These results promote the porcine C9 (pC9) as a candidate gene to improve general animal health in the future. PMID:26194222

  5. Genetic Association of the Porcine C9 Complement Component with Hemolytic Complement Activity

    PubMed Central

    Khoa, D. V. A.; Wimmers, K.

    2015-01-01

    The complement system is a part of the natural immune regulation mechanism against invading pathogens. Complement activation from three different pathways (classical, lectin, and alternative) leads to the formation of C5-convertase, an enzyme for cleavage of C5 into C5a and C5b, followed by C6, C7, C8, and C9 in membrane attack complex. The C9 is the last complement component of the terminal lytic pathway, which plays an important role in lysis of the target cells depending on its self-polymerization to form transmembrane channels. To address the association of C9 with traits related to disease resistance, the complete porcine C9 cDNA was comparatively sequenced to detect single nucleotide polymorphisms (SNPs) in pigs of the breeds Hampshire (HS), Duroc (DU), Berlin miniature pig (BMP), German Landrace (LR), Pietrain (PIE), and Muong Khuong (Vietnamese potbelly pig). Genotyping was performed in 417 F2 animals of a resource population (DUMI: DU×BMP) that were vaccinated with Mycoplasma hyopneumoniae, Aujeszky diseases virus and porcine respiratory and reproductive syndrome virus at 6, 14 and 16 weeks of age, respectively. Two SNPs were detected within the third exon. One of them has an amino acid substitution. The European porcine breeds (LR and PIE) show higher allele frequency of these SNPs than Vietnamese porcine breed (MK). Association of the substitution SNP with hemolytic complement activity indicated statistically significant differences between genotypes in the classical pathway but not in the alternative pathway. The interactions between eight time points of measurement of complement activity before and after vaccinations and genotypes were significantly different. The difference in hemolytic complement activity in the both pathways depends on genotype, kind of vaccine, age and the interaction to the other complement components. These results promote the porcine C9 (pC9) as a candidate gene to improve general animal health in the future. PMID:26194222

  6. Susceptibility to advanced age-related macular degeneration and alleles of complement factor H, complement factor B, complement component 2, complement component 3, and age-related maculopathy susceptibility 2 genes in a Mexican population

    PubMed Central

    Buentello-Volante, Beatriz; Rodriguez-Ruiz, Gabriela; Miranda-Duarte, Antonio; Pompa-Mera, Ericka N.; Graue-Wiechers, Federico; Bekker-Méndez, Carolina; Ayala-Ramirez, Raul; Quezada, Carlos; Rodríguez-Loaiza, Jose L.

    2012-01-01

    Purpose To investigate the association of age-related macular degeneration (AMD)–high risk alleles of the complement factor H (CFH), complement factor B (CFB), complement component 2 (C2), complement component 3 (C3), and age-related maculopathy susceptibility 2 (ARMS2) genes in a Mexican population for the first time. Methods Genotyping was performed for the Y402H variant of CFH, for the L9H, R32Q, and K565E variants of CFB, the E318D variant of C2, the A69S variant of ARMS2, and the R102G variant of C3 in 159 Mexican mestizo patients at advanced stages of AMD, i.e., CARMS (Clinical Age-Related Maculopathy Staging System) grade 4 or 5. The frequency of these variants was also investigated in a group of 152 control subjects without AMD. Genomic DNA was extracted from blood leukocytes, and genotyping was performed using PCR followed by direct sequencing. Allele-specific restriction enzyme digestion was used to detect the R102G polymorphism in C3. Results There were significant differences in the allelic distribution between the two groups for CFH Y402H (p=1×10−5), ARMS A69S (p=4×10−7), and CFB R32Q (p=0.01). The odds ratios (95% confidence interval) obtained for the risk alleles of these three variants were 3.8 (2.4–5.9), 3.04 (2.2–4.3), and 2.5 (1.1–5.7), respectively. Haplotype analysis including the two most significantly associated alleles (CFH Y402H and ARMS A69S) indicated that the C-T combination conferred an odds ratio (95% confidence interval) of 6.9 (3.2–14.8). The exposed attributable risk for this particular haplotype was 85.5%. Conclusions This is the first case-control investigation of AMD–high risk alleles in a Latino population. Our results support that CFH, ARMS2, and CFB AMD-risk alleles are consistently associated with the disease, even in ethnic groups with a complex admixture of ancestral populations such as Mexican mestizos. PMID:23112567

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

    PubMed

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

    2016-05-01

    Plasminogen is a single-chain glycoprotein found in human plasma as the inactive precursor of plasmin. When converted to proteolytically active plasmin, plasmin(ogen) regulates both complement and coagulation cascades, thus representing an important target for pathogenic microorganisms. Leptospira interrogans binds plasminogen, which is converted to active plasmin. Leptospiral immunoglobulin-like (Lig) proteins are surface exposed molecules that interact with extracellular matrix components and complement regulators, including proteins of the FH family and C4BP. In this work, we demonstrate that these multifunctional molecules also bind plasminogen through both N- and C-terminal domains. These interactions are dependent on lysine residues and are affected by ionic strength. Competition assays suggest that plasminogen does not share binding sites with C4BP or FH on Lig proteins at physiological molar ratios. Plasminogen bound to Lig proteins is converted to proteolytic active plasmin in the presence of urokinase-type plasminogen activator (uPA). Lig-bound plasmin is able to cleave the physiological substrates fibrinogen and the complement proteins C3b and C5. Taken together, our data point to a new role of LigA and LigB in leptospiral invasion and complement immune evasion. Plasmin(ogen) acquisition by these versatile proteins may contribute to Leptospira infection, favoring bacterial survival and dissemination inside the host. PMID:26822552

  8. Vaccine-Induced Human Antibodies to PspA Augment Complement C3 Deposition on Streptococcus pneumoniae

    PubMed Central

    Ochs, Martina M.; Bartlett, William; Briles, David E.; Hicks, Bryony; Jurkuvenas, Audra; Lau, Peggy; Ren, Bing; Millar, Amanda

    2008-01-01

    Pneumococcal surface protein (PspA) is a virulence factor expressed by all clinical isolates of Streptococcus pneumoniae. PspAs are variable in structure and have been grouped into clades and cross-reacting families based on sequence similarities and immunologic cross-reactivity. At least 98 percent of PspAs are found in PspA families 1 or 2. PspA has been shown to interfere with complement deposition on pneumococci, thus reducing opsonization and clearance of bacteria by the host immune system. Prior studies using pooled human sera have shown that PspA interferes with C3 deposition on a single strain of S. pneumoniae, WU2, and that mouse antibody to PspA can enhance the deposition of C3 on WU2. The present studies have demonstrated that these previous findings are representative of most normal human sera and each of 7 different strains of S. pneumoniae. It was observed that PspAs of PspA families 1 and 2 could inhibit C3 deposition in the presence of immunoglobulin present in all but 3 of 22 normal human sera. These studies have also demonstrated that rabbit and human antibody to PspA can enhance the deposition of C3 on pneumococci expressing either family 1 or 2 PspAs and either capsular types 2, 3, or 11. A vaccine candidate that can elicit immunity that neutralizes or compensates for S. pneumoniae’s ability to thwart host immunity would be of value. PMID:18006268

  9. The novel complement inhibitor human CUB and Sushi multiple domains 1 (CSMD1) protein promotes factor I-mediated degradation of C4b and C3b and inhibits the membrane attack complex assembly.

    PubMed

    Escudero-Esparza, Astrid; Kalchishkova, Nikolina; Kurbasic, Emila; Jiang, Wen G; Blom, Anna M

    2013-12-01

    CUB and Sushi multiple domains 1 (CSMD1) is a transmembrane protein containing 15 consecutive complement control protein (CCP) domains, which are characteristic for complement inhibitors. We expressed a membrane-bound fragment of human CSMD1 composed of the 15 C-terminal CCP domains and demonstrated that it inhibits deposition of C3b by the classical pathway on the surface of Chinese hamster ovary cells by 70% at 6% serum and of C9 (component of membrane attack complex) by 90% at 1.25% serum. Furthermore, this fragment of CSMD1 served as a cofactor to factor I-mediated degradation of C3b. In all functional assays performed, well-characterized complement inhibitors were used as positive controls, whereas Coxsackie adenovirus receptor, a protein with no effect on complement, was a negative control. Moreover, attenuation of expression in human T47 breast cancer cells that express endogenous CSMD1 significantly increased C3b deposition on these cells by 45% at 8% serum compared with that for the controls. Furthermore, by expressing a soluble 17-21 CCP fragment of CSMD1, we found that CSMD1 inhibits complement by promoting factor I-mediated C4b/C3b degradation and inhibition of MAC assembly at the level of C7. Our results revealed a novel complement inhibitor for the classical and lectin pathways. PMID:23964079

  10. Complement Component 3 Is Associated with Metabolic Comorbidities in Older HIV-Positive Adults.

    PubMed

    Bryant, Alex K; Fazeli, Pariya L; Letendre, Scott L; Ellis, Ronald J; Potter, Michael; Burdo, Tricia H; Singh, Kumud K; Jeste, Dilip V; Grant, Igor; Moore, David J

    2016-03-01

    Our objective was to evaluate the association of plasma inflammatory biomarkers with MetS in an older population of treated HIV-infected (HIV(+)) as compared to age-matched HIV-negative (HIV(-)) adults. This was done in a retrospective observational study. Plasma concentrations of complement component 3 (C3), cystatin C, fibroblast growth factor 1, interleukin 6, oxidized LDL, soluble RAGE, soluble CD163, soluble CD14, and osteopontin were measured in 79 HIV(+) participants on combination antiretroviral treatment (cART) with a suppressed HIV viral load and 47 HIV(-) participants with a median age of 59 (range 50 to 79). Outcomes were individual MetS components (hypertension, type II diabetes, dyslipidemia, and obesity) and MetS. Covariates were screened for inclusion in multivariable models. Odds ratios are reported per 50 mg/dl increase in C3. In the HIV(+) group, higher C3 levels were associated with MetS (OR 3.19, p = 0.004), obesity (OR 2.02, p = 0.01), type II diabetes (OR 1.93, p = 0.02), and at a trend level with dyslipidemia (OR 1.87, p = 0.07) and hypertension (OR 1.66, p = 0.09). C3 levels were significantly higher in HIV(+) participants with MetS compared to those without MetS (p = 0.002). C3 was higher among HIV(+) patients with three or four MetS components as compared to those with one or two (p = 0.04) and those with none (p = 0.002). No associations were found between C3 and the outcomes for HIV(-) participants. C3 is strongly associated with both MetS and MetS components in an older HIV(+) sample on cART compared to HIV(-) controls. C3 warrants further investigation as a marker of cardiometabolic risk among persons aging with HIV. PMID:26499082

  11. CR2 is the primary acceptor site for C3 during alternative pathway activation of complement on human peripheral B lymphocytes.

    PubMed

    Marquart, H V; Svehag, S E; Leslie, R G

    1994-07-01

    Human cells infected with certain viruses acquire the ability to activate the alternative pathway (AP) of complement. Complement receptor 2 on EBV-infected lymphoblastoid cell lines has been reported to act as the covalent binding site for C3b during AP activation. Using flow cytometry, we investigated the ability of normal human peripheral blood leukocytes to activate the AP in homologous serum. Deposition of C3 fragments was determined as a measurement of complement activation on each of the subpopulations of the blood cells. Incubating human peripheral blood leukocytes with homologous or autologous serum resulted in C3 deposition on B cells and, to a lesser extent, on monocytes and polymorphonuclear leukocytes. Complement activation in the presence of Mg2+ ions and EGTA revealed major involvement of the AP in the case of B cells, and to a lesser extent for other leukocyte populations examined. Preincubation of the leukocytes with polyclonal anti-complement receptor 2 Ab markedly decreased the C3 fragment deposition, as a result of in vitro AP activation, on B cells, indicating that on normal human B cells this receptor may be involved in AP activation. Freshly isolated, normal human B cells also bear low but significant amounts of C3d,g fragments on their membranes, indicating that this AP activation also occurs in vivo. AP activation was partially decreased in the presence of autologous erythrocytes (RBC) suggesting that complement regulatory proteins on RBC play a role in limiting the AP activation in vivo. PMID:7515925

  12. Stringent Regulation of Complement Lectin Pathway C3/C5 Convertase By C4b-Binding Protein (C4bp)

    PubMed Central

    Rawal, Nenoo; Rajagopalan, Rema; Salvi, Veena P.

    2009-01-01

    The complement lectin pathway, an essential component of the innate immune system, is geared for rapid recognition of infections as each C4b deposited via this pathway is capable of forming a C3/C5 convertase. In the present study, role of C4b-binding protein (C4BP) in regulating the lectin pathway C3/C5 convertase assembled on zymosan and sheep erythrocytes coated with mannan (EMan) was examined. While the C4BP concentration for inhibiting 50% (IC50) formation of surface-bound C3 convertase on the two surfaces was similar to that obtained for the soluble C3 convertase (1.05 nM), ∼3- and 41-fold more was required to inhibit assembly of the C5 convertase on zymosan (2.81 nM) and EMan (42.66 nM). No difference in binding interactions between C4BP and surface-bound C4b alone or in complex with C3b was observed. Increasing the C4b density on zymosan (14,000-431,000 C4b/Zym) increased the number of C4b bound per C4BP from 2.87 to 8.23 indicating that at high C4b density all seven α-chains of C4BP are engaged in C4b-binding. In contrast, the number of C4b bound per C4BP remained constant (3.79 ± 0.60) when the C4b density on EMan was increased. The data also show that C4BP regulates assembly and decay of the lectin pathway C3/C5 convertase more stringently than the classical pathway C3/C5 convertase because of a ∼7 to 13-fold greater affinity for C4b deposited via the lectin pathway than the classical pathway. C4BP thus regulates efficiently the four times greater potential of the lectin pathway than the classical pathway in generating the C3/C5 convertase and hence production of pro-inflammatory products, which are required to fight infections but occasionally cause pathological inflammatory reactions. PMID:19660812

  13. Schizophrenia risk from complex variation of complement component 4.

    PubMed

    Sekar, Aswin; Bialas, Allison R; de Rivera, Heather; Davis, Avery; Hammond, Timothy R; Kamitaki, Nolan; Tooley, Katherine; Presumey, Jessy; Baum, Matthew; Van Doren, Vanessa; Genovese, Giulio; Rose, Samuel A; Handsaker, Robert E; Daly, Mark J; Carroll, Michael C; Stevens, Beth; McCarroll, Steven A

    2016-02-11

    Schizophrenia is a heritable brain illness with unknown pathogenic mechanisms. Schizophrenia's strongest genetic association at a population level involves variation in the major histocompatibility complex (MHC) locus, but the genes and molecular mechanisms accounting for this have been challenging to identify. Here we show that this association arises in part from many structurally diverse alleles of the complement component 4 (C4) genes. We found that these alleles generated widely varying levels of C4A and C4B expression in the brain, with each common C4 allele associating with schizophrenia in proportion to its tendency to generate greater expression of C4A. Human C4 protein localized to neuronal synapses, dendrites, axons, and cell bodies. In mice, C4 mediated synapse elimination during postnatal development. These results implicate excessive complement activity in the development of schizophrenia and may help explain the reduced numbers of synapses in the brains of individuals with schizophrenia. PMID:26814963

  14. Schizophrenia risk from complex variation of complement component 4

    PubMed Central

    Sekar, Aswin; Bialas, Allison R.; de Rivera, Heather; Davis, Avery; Hammond, Timothy R.; Kamitaki, Nolan; Tooley, Katherine; Presumey, Jessy; Baum, Matthew; Van Doren, Vanessa; Genovese, Giulio; Rose, Samuel A.; Handsaker, Robert E.; Daly, Mark J.; Carroll, Michael C.; Stevens, Beth; McCarroll, Steven A.

    2016-01-01

    Schizophrenia is a heritable brain illness with unknown pathogenic mechanisms. Schizophrenia’s strongest genetic association at a population level involves variation in the Major Histocompatibility Complex (MHC) locus, but the genes and molecular mechanisms accounting for this have been challenging to recognize. We show here that schizophrenia’s association with the MHC locus arises in substantial part from many structurally diverse alleles of the complement component 4 (C4) genes. We found that these alleles promoted widely varying levels of C4A and C4B expression and associated with schizophrenia in proportion to their tendency to promote greater expression of C4A in the brain. Human C4 protein localized at neuronal synapses, dendrites, axons, and cell bodies. In mice, C4 mediated synapse elimination during postnatal development. These results implicate excessive complement activity in the development of schizophrenia and may help explain the reduced numbers of synapses in the brains of individuals affected with schizophrenia. PMID:26814963

  15. Deficiency of the Complement Component 3 but Not Factor B Aggravates Staphylococcus aureus Septic Arthritis in Mice

    PubMed Central

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

    2016-01-01

    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

  16. C3 functionalization of indolizines via In(iii)-catalyzed three-component reaction.

    PubMed

    Jung, Youngeun; Kim, Ikyon

    2015-12-01

    Post-functionalization at the C3 position of indolizines via In(iii)-catalyzed three-component coupling reaction with amines and aldehydes allowed rapid access to a new class of indolizines with diverse functional groups at the C3 position in good to excellent yields. PMID:26380932

  17. Genetic Deficiency of Complement Component 3 Does Not Alter Disease Progression in a Mouse Model of Huntington's Disease

    PubMed Central

    Larkin, Paul B.; Muchowski, Paul J.

    2012-01-01

    Several genes and proteins of the complement cascade are present at elevated levels in brains of patients with Huntington's disease (HD). The complement cascade is well characterized as an effector arm of the immune system, and in the brain it is important for developmental synapse elimination. We hypothesized that increased levels of complement in HD brains contributes to disease progression, perhaps by contributing to synapse elimination or inflammatory signaling. We tested this hypothesis in the R6/2 mouse model of HD by crossing mice deficient in complement component 3 (C3), a crucial complement protein found at increased levels in HD brains, to R6/2 mice and monitoring behavioral and neuropathological disease progression. We found no alterations in multiple behavioral assays, weight or survival in R6/2 mice lacking C3. We also quantified the expression of several complement cascade genes in R6/2 brains and found that the large scale upregulation of complement genes observed in HD brains is not mirrored in R6/2 brains. These data show that C3 deficiency does not alter disease progression in the R6/2 mouse model of HD. PMID:23097680

  18. Genetic Deficiency of Complement Component 3 Does Not Alter Disease Progression in a Mouse Model of Huntington's Disease.

    PubMed

    Larkin, Paul B; Muchowski, Paul J

    2012-01-01

    Several genes and proteins of the complement cascade are present at elevated levels in brains of patients with Huntington's disease (HD). The complement cascade is well characterized as an effector arm of the immune system, and in the brain it is important for developmental synapse elimination. We hypothesized that increased levels of complement in HD brains contributes to disease progression, perhaps by contributing to synapse elimination or inflammatory signaling. We tested this hypothesis in the R6/2 mouse model of HD by crossing mice deficient in complement component 3 (C3), a crucial complement protein found at increased levels in HD brains, to R6/2 mice and monitoring behavioral and neuropathological disease progression. We found no alterations in multiple behavioral assays, weight or survival in R6/2 mice lacking C3. We also quantified the expression of several complement cascade genes in R6/2 brains and found that the large scale upregulation of complement genes observed in HD brains is not mirrored in R6/2 brains. These data show that C3 deficiency does not alter disease progression in the R6/2 mouse model of HD. PMID:23097680

  19. A New Role of the Complement System: C3 Provides Protection in a Mouse Model of Lung Infection with Intracellular Chlamydia psittaci

    PubMed Central

    Bode, Jenny; Dutow, Pavel; Sommer, Kirsten; Janik, Katrin; Glage, Silke; Tümmler, Burkhard; Munder, Antje; Laudeley, Robert; Sachse, Konrad W.; Klos, Andreas

    2012-01-01

    The complement system modulates the intensity of innate and specific immunity. While it protects against infections by extracellular bacteria its role in infection with obligate intracellular bacteria, such as the avian and human pathogen Chlamydia (C.) psittaci, is still unknown. In the present study, knockout mice lacking C3 and thus all main complement effector functions were intranasally infected with C. psittaci strain DC15. Clinical parameters, lung histology, and cytokine levels were determined. A subset of infections was additionally performed with mice lacking C5 or C5a receptors. Complement activation occurred before symptoms of pneumonia appeared. Mice lacking C3 were ∼100 times more susceptible to the intracellular bacteria compared to wild-type mice, with all C3−/− mice succumbing to infection after day 9. At a low infective dose, C3−/− mice became severely ill after an even longer delay, the kinetics suggesting a so far unknown link of complement to the adaptive, protective immune response against chlamydiae. The lethal phenotype of C3−/− mice is not based on differences in the anti-chlamydial IgG response (which is slightly delayed) as demonstrated by serum transfer experiments. In addition, during the first week of infection, the absence of C3 was associated with partial protection characterized by reduced weight loss, better clinical score and lower bacterial burden, which might be explained by a different mechanism. Lack of complement functions downstream of C5 had little effect. This study demonstrates for the first time a strong and complex influence of complement effector functions, downstream of C3 and upstream of C5, on the outcome of an infection with intracellular bacteria, such as C. psittaci. PMID:23189195

  20. Microbe-specific C3b deposition in the horseshoe crab complement system in a C2/factor B-dependent or -independent manner.

    PubMed

    Tagawa, Keisuke; Yoshihara, Toyoki; Shibata, Toshio; Kitazaki, Kazuki; Endo, Yuichi; Fujita, Teizo; Koshiba, Takumi; Kawabata, Shun-ichiro

    2012-01-01

    Complement C3 plays an essential role in the opsonization of pathogens in the mammalian complement system, whereas the molecular mechanism underlying C3 activation in invertebrates remains unknown. To understand the molecular mechanism of C3b deposition on microbes, we characterized two types of C2/factor B homologs (designated TtC2/Bf-1 and TtC2/Bf-2) identified from the horseshoe crab Tachypleus tridentatus. Although the domain architectures of TtC2/Bf-1 and TtC2/Bf-2 were identical to those of mammalian homologs, they contained five-repeated and seven-repeated complement control protein domains at their N-terminal regions, respectively. TtC2/Bf-1 and TtC2/Bf-2 were synthesized and glycosylated in hemocytes and secreted to hemolymph plasma, which existed in a complex with C3 (TtC3), and their activation by microbes was absolutely Mg(2+)-dependent. Flow cytometric analysis revealed that TtC3b deposition was Mg(2+)-dependent on Gram-positive bacteria or fungi, but not on Gram-negative bacteria. Moreover, this analysis demonstrated that Ca(2+)-dependent lectins (C-reactive protein-1 and tachylectin-5A) were required for TtC3b deposition on Gram-positive bacteria, and that a Ca(2+)-independent lectin (Tachypleus plasma lectin-1) was definitely indispensable for TtC3b deposition on fungi. In contrast, a horseshoe crab lipopolysaccharide-sensitive protease factor C was necessary and sufficient to deposit TtC3b on Gram-negative bacteria. We conclude that plasma lectins and factor C play key roles in microbe-specific TtC3b deposition in a C2/factor B-dependent or -independent manner. PMID:22611464

  1. Microbe-Specific C3b Deposition in the Horseshoe Crab Complement System in a C2/Factor B-Dependent or -Independent Manner

    PubMed Central

    Tagawa, Keisuke; Yoshihara, Toyoki; Shibata, Toshio; Kitazaki, Kazuki; Endo, Yuichi; Fujita, Teizo; Koshiba, Takumi; Kawabata, Shun-ichiro

    2012-01-01

    Complement C3 plays an essential role in the opsonization of pathogens in the mammalian complement system, whereas the molecular mechanism underlying C3 activation in invertebrates remains unknown. To understand the molecular mechanism of C3b deposition on microbes, we characterized two types of C2/factor B homologs (designated TtC2/Bf-1 and TtC2/Bf-2) identified from the horseshoe crab Tachypleus tridentatus. Although the domain architectures of TtC2/Bf-1 and TtC2/Bf-2 were identical to those of mammalian homologs, they contained five-repeated and seven-repeated complement control protein domains at their N-terminal regions, respectively. TtC2/Bf-1 and TtC2/Bf-2 were synthesized and glycosylated in hemocytes and secreted to hemolymph plasma, which existed in a complex with C3 (TtC3), and their activation by microbes was absolutely Mg2+-dependent. Flow cytometric analysis revealed that TtC3b deposition was Mg2+-dependent on Gram-positive bacteria or fungi, but not on Gram-negative bacteria. Moreover, this analysis demonstrated that Ca2+-dependent lectins (C-reactive protein-1 and tachylectin-5A) were required for TtC3b deposition on Gram-positive bacteria, and that a Ca2+-independent lectin (Tachypleus plasma lectin-1) was definitely indispensable for TtC3b deposition on fungi. In contrast, a horseshoe crab lipopolysaccharide-sensitive protease factor C was necessary and sufficient to deposit TtC3b on Gram-negative bacteria. We conclude that plasma lectins and factor C play key roles in microbe-specific TtC3b deposition in a C2/factor B-dependent or -independent manner. PMID:22611464

  2. Identification of three physically and functionally distinct binding sites for C3b in human complement factor H by deletion mutagenesis.

    PubMed Central

    Sharma, A K; Pangburn, M K

    1996-01-01

    Human complement factor H controls spontaneous activation of complement in plasma and appears to play a role in distinguishing host cells from activators of the alternative pathway of complement. In both mice and humans, the protein is composed of 20 homologous short consensus repeat (SCR) domains. The size of the protein suggests that portions of the structure outside the known C3b binding site (SCR 1-4) possess a significant biological role. We have expressed the full-length cDNA of factor H in the baculovirus system and have shown the recombinant protein to be fully active. Mutants of this full-length protein have now been prepared, purified, and examined for cofactor activity and binding to C3b and heparin. The results demonstrate (i) that factor H has at least three sites that bind C3b, (ii) that one of these sites is located in SCR domains 1-4, as has been shown by others, (iii) that a second site exists in the domain 6-10 region, (iv) that a third site resides in the SCR 16-20 region, and (v) that two heparin binding sites exist in factor H, one near SCR 13 and another in the SCR 6-10 region. Functional assays demonstrated that only the first C3b site located in SCR 1-4 expresses factor I cofactor activity. Mutant proteins lacking any one of the three C3b binding sites exhibited 6- to 8-fold reductions in affinity for C3b on sheep erythrocytes, indicating that all three sites contribute to the control of complement activation on erythrocytes. The identification of multiple functionally distinct sites on factor H clarifies many of the heretofore unexplainable behaviors of this protein, including the heterogeneous binding of factor H to surface-bound C3b, the effects of trypsin cleavage, and the differential control of complement activation on activators and nonactivators of the alternative pathway of complement. Images Fig. 2 Fig. 3 PMID:8855297

  3. Control of the collective migration of enteric neural crest cells by the Complement anaphylatoxin C3a and N-cadherin

    PubMed Central

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

    2016-01-01

    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-cad-herin 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-cad-herin-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

  4. Control of the collective migration of enteric neural crest cells by the Complement anaphylatoxin C3a and N-cadherin.

    PubMed

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

    2016-06-01

    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

  5. Structure-function analysis of the Anopheles gambiae LRIM1/APL1C complex and its interaction with complement C3-like protein TEP1.

    PubMed

    Povelones, Michael; Upton, Leanna M; Sala, Katarzyna A; Christophides, George K

    2011-04-01

    Malaria threatens half the world's population and exacts a devastating human toll. The principal malaria vector in Africa, the mosquito Anopheles gambiae, encodes 24 members of a recently identified family of leucine-rich repeat proteins named LRIMs. Two members of this family, LRIM1 and APL1C, are crucial components of the mosquito complement-like pathway that is important for immune defense against Plasmodium parasites. LRIM1 and APL1C circulate in the hemolymph exclusively as a disulfide-bonded complex that specifically interacts with the mature form of the complement C3-like protein, TEP1. We have investigated the specificity of LRIM1/APL1C complex formation and which regions of these proteins are required for interactions with TEP1. To address these questions, we have generated a set of LRIM1 and APL1C alleles altering key conserved structural elements and assayed them in cell culture for complex formation and interaction with TEP1. Our data indicate that heterocomplex formation is an intrinsic ability of LRIM1 and APL1C and identify key homologous cysteine residues forming the intermolecular disulfide bond. We also demonstrate that the coiled-coil domain is the binding site for TEP1 but also contributes to the specificity of LRIM1/APL1C complex formation. In addition, we show that the LRIM1/APL1C complex interacts with the mature forms of three other TEP proteins, one of which, TEP3, we have characterized as a Plasmodium antagonist. We conclude that LRIM1 and APL1C contain three distinct modules: a C-terminal coiled-coil domain that can carry different TEP protein cargoes, potentially with distinct functions, a central cysteine-rich region that controls complex formation and an N-terminal leucine-rich repeat with a putative role in pathogen recognition. PMID:21533217

  6. 21 CFR 866.5240 - Complement components immunological test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... tissues. Complement is a group of serum proteins which destroy infectious agents. Measurements of these proteins aids in the diagnosis of immunologic disorders, especially those associated with deficiencies...

  7. cDNA sequence coding for the alpha'-chain of the third complement component in the African lungfish.

    PubMed

    Sato, A; Sültmann, H; Mayer, W E; Figueroa, F; Tichy, H; Klein, J

    1999-04-01

    cDNA clones coding for almost the entire C3 alpha-chain of the African lungfish (Protopterus aethiopicus), a representative of the Sarcopterygii (lobe-finned fishes), were sequenced and characterized. From the sequence it is deduced that the lungfish C3 molecule is probably a disulphide-bonded alpha:beta dimer similar to that of the C3 components of other jawed vertebrates. The deduced sequence contains conserved sites presumably recognized by proteolytic enzymes (e.g. factor I) involved in the activation and inactivation of the component. It also contains the conserved thioester region and the putative site for binding properdin. However, the site for the interaction with complement receptor 2 and factor H are poorly conserved. Either complement receptor 2 and factor H are not present in the lungfish or they bind to different residues at the same or a different site than mammalian complement receptor 2 and factor H. The C3 alpha-chain sequences faithfully reflect the phylogenetic relationships among vertebrate classes and can therefore be used to help to resolve the long-standing controversy concerning the origin of the tetrapods. PMID:10219761

  8. Molecular genetics of the fourth component of human complement

    SciTech Connect

    Carroll, M.C.

    1987-05-15

    The fourth component of complement in humans is coded for by two closely linked loci, i.e., C4A and C4B, that have been positioned within the class III region of the human major histocompatibility complex along with the genes for C2, Bf, and steroid 21-OH. Both C4 loci are highly polymorphic and certain alleles, particularly the nulls, are associated with susceptibility to autoimmune disease. About one-half of the null alleles are due to a large deletion that includes both a C4 and flanking 21-OH gene. Despite the near identity of the products of the two loci, the proteins differ dramatically in their efficiency of covalent binding to antigen. The amino acid substitutions responsible for the functional differences have been identified and they are clustered relatively near the covalent binding site within the C4d region of the ..cap alpha.. chain. These observations support the hypothesis that the susceptibility to autoimmune disease is related to the structural variation of the C4 protein.

  9. Joint phenotype distribution at the esterase D and complement C3 loci in the Upper Silesia population (Poland).

    PubMed

    Raczek, E; Kabiesz, J

    1995-01-01

    Among 1,239 unrelated adults from Upper Silesia (Poland), a significant association between ESD and C3 phenotypes was found. This is in accordance with the results obtained in an Indian population. PMID:7896302

  10. Complement component 3 inhibition by an antioxidant is neuroprotective after cerebral ischemia and reperfusion in mice

    PubMed Central

    Yang, Jiwon; Ahn, Hye-na; Chang, Minsun; Narasimhan, Purnima; Chan, Pak H.; Song, Yun Seon

    2012-01-01

    Oxidative stress after stroke is associated with the inflammatory system activation in the brain. The complement cascade, especially the degradation products of complement component 3, is a key inflammatory mediator of cerebral ischemia. We have shown that proinflammatory complement component 3 is increased by oxidative stress after ischemic stroke in mice using DNA array. In this study, we investigated whether up-regulation of complement component 3 is directly related to oxidative stress after transient focal cerebral ischemia in mice and oxygen-glucose deprivation in brain cells. Persistent up-regulation of complement component 3 expression was reduced in copper/zinc-superoxide dismutase transgenic mice, and manganese-superoxide dismutase knockout mice showed highly increased complement component 3 levels after transient focal cerebral ischemia. Antioxidant N-tert-butyl-α-phenylnitrone treatment suppressed complement component 3 expression after transient focal cerebral ischemia. Accumulation of complement component 3 in neurons and microglia was decreased by N-tert-butyl-α-phenylnitrone, which reduced infarct volume and impaired neurological deficiency after cerebral ischemia and reperfusion in mice. Small interfering RNA specific for complement component 3 transfection showed a significant increase in brain cells viability after oxygen-glucose deprivation. Our study suggests that the neuroprotective effect of antioxidants through complement component 3 suppression is a new strategy for potential therapeutic approaches in stroke. PMID:23199288

  11. Complement component C7 deficiency in a Spanish family.

    PubMed

    Vázquez-Bermúdez, M F; Barroso, S; Walter, K; Alvarez, A J; Alarcón, A; López-Trascasa, M; Wichmann, I; Aguilar, F; Núñez-Roldán, A; Sánchez, B

    2003-08-01

    Different genetic mutations have been described in complement component C7 deficiency, a molecular defect which is clinically associated with an increased susceptibility to neisserial recurrent infections, although some cases remain asymptomatic. In this work we report the genetic bases of C7 deficiency in one Spanish family. Exon-specific PCR and sequencing revealed a novel point mutation at nucleotide 615 (exon 6) leading to a stop codon (UGG to UGA) in the patient, his mother, and sister. This transversion causes the premature truncation of the C7 protein (W183X). Additionally, we detected a missense mutation at position 1135 (exon 9) located in the first nucleotide of the codon GGG (CGG), resulting in an amino acid change (G357R) in the patient, his father, as well as in his sister. This latter mutation had been previously described in individuals from Moroccan Sephardic Jewish ancestry. Since both heterozygous mutations were found in the patient as well as in his asymptomatic sister, we analyse other meningococcal defence mechanisms such as polymorphisms of the opsonin receptors on polymorphonuclear cells. Results showed that the patient and his sister bore identical combinations of FcgammaRIIA-H/R131 and FcgammaRIIIB-NA1/2 allotypes. Our results provide further evidence that the molecular pathogenesis of C7 deficiency as well as susceptibility to meningococcal disease are heterogeneous, since different families carry different molecular defects, although many of the C7 defects appear to be homogeneous in individuals from certain geographical areas. The missense mutation G357R would make an interesting topic of analysis with regard to meningococcal disease susceptibility in the Spanish population. PMID:12869030

  12. Complement component C7 deficiency in two Spanish families

    PubMed Central

    Barroso, Sonia; Sánchez, Berta; Álvarez, Antonia José; López-Trascasa, Margarita; Lanuza, Amparo; Luque, Rafael; Wichmann, Ingeborg; Núñez-Roldán, Antonio

    2004-01-01

    Different genetic mutations have been described in complement component C7 deficiency, a molecular defect clinically associated with an increased susceptibility to neisserial recurrent infections. In this work we report the genetic basis of C7 deficiency in two different Spanish families (family 1 and family 2). In family 1, of Gypsy ethnical background, exon-specific polymerase chain reaction and sequencing revealed a not previously described single base deletion of nucleotide 1309 (exon 10) in the patient, as well as in her father, leading to a stop codon that causes the premature truncation of the C7 protein (K416 X 419). Additionally, the patient and her mother displayed a missense mutation at position 1135 (exon 9) located in the first nucleotide of the codon GGG (CGG), resulting in a change of amino acid (G357R). This mutation was firstly described in individuals of Moroccan Sephardic Jewish ancestry and has been also reported among Spaniards. In family 2, another novel mutation was found in homozygosity in two siblings; a two base-pair deletion of nucleotides 1922 and 1923 in exon 14 leading to the generation of a downstream stop codon causing the truncation of the C7 protein product (S620 X 630). Our results provide more evidence for the heterogeneous molecular basis of C7 deficiency as well as for the subsequent susceptibility to meningococcal disease, since different families carry different molecular defects. On the other hand, certain C7 defects appear to be prevalent in individuals from certain populations or living in defined geographical areas. PMID:15554930

  13. Complement anaphylatoxin receptors C3aR and C5aR are required in the pathogenesis of experimental autoimmune uveitis.

    PubMed

    Zhang, Lingjun; Bell, Brent A; Yu, Minzhong; Chan, Chi-Chao; Peachey, Neal S; Fung, John; Zhang, Xiaoming; Caspi, Rachel R; Lin, Feng

    2016-03-01

    Recent studies have suggested that reagents inhibiting complement activation could be effective in treating T cell mediated autoimmune diseases such as autoimmune uveitis. However, the precise role of the complement anaphylatoxin receptors (C3a and C5a receptors) in the pathogenesis of autoimmune uveitis remains elusive and controversial. We induced experimental autoimmune uveitis in mice deficient or sufficient in both C3a and C5a receptors and rigorously compared their retinal phenotype using various imaging techniques, including indirect ophthalmoscopy, confocal scanning laser ophthalmoscopy, spectral domain optical coherence tomography, topical endoscopic fundus imaging, and histopathological analysis. We also assessed retinal function using electroretinography. Moreover, we performed Ag-specific T cell recall assays and T cell adoptive transfer experiments to compare pathogenic T cell activity between wild-type and knockout mice with experimental autoimmune uveitis. These experiments showed that C3a receptor/C5a receptor-deficient mice developed much less severe uveitis than did control mice using all retinal examination methods and that these mice had reduced pathogenic T cell responses. Our data demonstrate that both complement anaphylatoxin receptors are important for the development of experimental autoimmune uveitis, suggesting that targeting these receptors could be a valid approach for treating patients with autoimmune uveitis. PMID:26394814

  14. Characterization and expression analysis of a complement component gene in sea cucumber ( Apostichopus japonicus)

    NASA Astrophysics Data System (ADS)

    Chen, Zhong; Zhou, Zunchun; Yang, Aifu; Dong, Ying; Guan, Xiaoyan; Jiang, Bei; Wang, Bai

    2015-12-01

    The complement system plays a crucial role in the innate immune system of animals. It can be activated by distinct yet overlapping classical, alternative and lectin pathways. In the alternative pathway, complement factor B (Bf) serves as the catalytic subunit of complement component 3 (C3) convertase, which plays the central role among three activation pathways. In this study, the Bf gene in sea cucumber ( Apostichopus japonicus), termed AjBf, was obtained by rapid amplification of cDNA ends (RACE). The full-length cDNA of AjBf was 3231 bp in length barring the poly (A) tail. It contained an open reading frame (ORF) of 2742 bp encoding 913 amino acids, a 105 bp 5'-UTR (5'-terminal untranslated region) and a 384 bp 3'-UTR. AjBf was a mosaic protein with six CCP (complement control protein) domains, a VWA (von Willebrand factor A) domain, and a serine protease domain. The deduced molecular weight of AjBf protein was 101 kDa. Quantitative real time PCR (qRT-PCR) analysis indicated that the expression level of AjBf in A. japonicus was obviously higher at larval stage than that at embryonic stage. Expression detection in different tissues showed that AjBf expressed higher in coelomocytes than in other four tissues. In addation, AjBf expression in different tissues was induced significantly after LPS or PolyI:C challenge. These results indicated that AjBf plays an important role in immune responses to pathogen infection.

  15. Microarray reveals complement components are regulated in the serum-deprived rat retinal ganglion cell line

    PubMed Central

    Khalyfa, Abdelnaby; Chlon, Timothy; Qiang, He; Agarwal, Neeraj

    2007-01-01

    H (CFH), the major inhibitor of the alternative complement pathway is downregulated in serum-deprived RGC-5. CFH protein was detected within RGC-5 cells as well as the rat retina with the aid of immunocytochemistry and confocal microscopy. Conclusions This study was undertaken to generate a genome-wide gene expression profile of RGC-5 after serum deprivation, and to identify candidate and novel genes that may be involved in the signal transduction pathways leading to apoptosis. RGC-5 serum deprivation revealed up-and downregulation in gene expression profiles. The data gathered from this study was the first report that the genes identified in microarray data and validated by real-time RT-PCR may play an important role in RGC-5 cell death. Among the validated genes, C3 and C1s showed significant upregulation of the complement component pathway. The results further indicate that components of the complement pathway are present in neurons of the rat retina. The data indicated that complement factors are likely involved in the pathway leading to ganglion cell death in the serum-deprivation paradigm, which may be similar to the mechanism of cell death in glaucoma. PMID:17356516

  16. The disease-protective complement factor H allotypic variant Ile62 shows increased binding affinity for C3b and enhanced cofactor activity

    PubMed Central

    Tortajada, Agustín; Montes, Tamara; Martinez-Barricarte, Ruben; Morgan, B. Paul; Harris, Claire L.; de Córdoba, Santiago Rodríguez

    2011-01-01

    Summary Mutations and polymorphisms in the gene encoding factor H (CFH) have been associated with atypical haemolytic uraemic syndrome, dense deposit disease and age-related macular degeneration. The disease-predisposing CFH variants show a differential association with pathology that has been very useful to unravel critical events in the pathogenesis of one or other disease. In contrast, the fH-Ile62 polymorphism confers strong protection to all three diseases. Using ELISA-based methods and surface plasmon resonance analyses we show here that the protective fH-Ile62 variant binds more efficiently to C3b than fH-Val62 and competes better with factor B in proconvertase formation. Functional analyses demonstrate an increased cofactor activity for fH-Ile62 in the factor I-mediated cleavage of fluid phase and surface-bound C3b; however, the two fH variants show no differences in decay accelerating activity. From these data we conclude that the protective effect of the fH-Ile62 variant is due to its better capacity to bind C3b, inhibit proconvertase formation and catalyse inactivation of fluid-phase and surface-bound C3b. This demonstration of the functional consequences of the fH-Ile62 polymorphism provides relevant insights into the complement regulatory activities of fH that will be useful in disease prediction and future development of effective therapeutics for disorders caused by complement dysregulation. PMID:19549636

  17. Hereditary deficiency of the sixth component of complement in man. I. Immunochemical, biologic, and family studies.

    PubMed Central

    Leddy, J P; Frank, M M; Gaither, T; Baum, J; Klemperer, M R

    1974-01-01

    An 18-yr-old black woman in good general health was found to lack serum hemolytic complement activity. The sixth component of complement (C6) was undetectable by functional assay of serum or plasma and by immunoprecipitin analysis of serum. Functional titers of all other complement components were normal. The absence of C6 in the patient's serum could not be accounted for by a circulating C6 inhibitor, and addition of functionally pure C6 to the patient's serum restored hemolytic activity to normal. Both parents of the proband and five of six available siblings had approximately half the normal levels of functional C6. The other sibling had a normal C6 level. These data suggest that both parents and five siblings are heterozygous for C6 deficiency, while the proband is homozygous and one sibling is normal. Thus, C6 deficiency appears to follow classic mendelian inheritance, with all three possible genotypes recognizable within the family. Functional properties of the proband's C6-deficient serum included total absence of bactericidal activity against Salmonella typhi 0 901 and Hemophilus influenzae, type b, and inability to mediate lysis of red blood cells from patients with paroxysmal nocturnal hemoglobinuria in either the acidified serum or "sugar water" tests. The proband's serum did, however, exhibit a normal capacity (a) to generate chemotactic activity during incubation with bacterial endotoxin or aggregated IgG, (b) to mediate the immune adherence phenomenon, and (c) to coat human red blood cells, sensitized by cold agglutinins, with C4 and C3. Images PMID:11344568

  18. Human Astrovirus Coat Protein Inhibits Serum Complement Activation via C1, the First Component of the Classical Pathway▿

    PubMed Central

    Bonaparte, Rheba S.; Hair, Pamela S.; Banthia, Deepa; Marshall, Dawn M.; Cunnion, Kenji M.; Krishna, Neel K.

    2008-01-01

    Human astroviruses (HAstVs) belong to a family of nonenveloped, icosahedral RNA viruses that cause noninflammatory gastroenteritis, predominantly in infants. Eight HAstV serotypes have been identified, with a worldwide distribution. While the HAstVs represent a significant public health concern, very little is known about the pathogenesis of and host immune response to these viruses. Here we demonstrate that HAstV type 1 (HAstV-1) virions, specifically the viral coat protein (CP), suppress the complement system, a fundamental component of the innate immune response in vertebrates. HAstV-1 virions and purified CP both suppress hemolytic complement activity. Hemolytic assays utilizing sera depleted of individual complement factors as well as adding back purified factors demonstrated that HAstV CP suppresses classical pathway activation at the first component, C1. HAstV-1 CP bound the A chain of C1q and inhibited serum complement activation, resulting in decreased C4b, iC3b, and terminal C5b-9 formation. Inhibition of complement activation was also demonstrated for HAstV serotypes 2 to 4, suggesting that this phenomenon is a general feature of these human pathogens. Since complement is a major contributor to the initiation and amplification of inflammation, the observed CP-mediated inhibition of complement activity may contribute to the lack of inflammation associated with astrovirus-induced gastroenteritis. Although diverse mechanisms of inhibition of complement activation have been described for many enveloped animal viruses, this is the first report of a nonenveloped icosahedral virus CP inhibiting classical pathway activation at C1. PMID:17959658

  19. The Group B Streptococcus–Secreted Protein CIP Interacts with C4, Preventing C3b Deposition via the Lectin and Classical Complement Pathways

    PubMed Central

    Pietrocola, Giampiero; Rindi, Simonetta; Rosini, Roberto; Buccato, Scilla

    2016-01-01

    The group B Streptococcus (GBS) is a leading cause of neonatal invasive disease. GBS bacteria are surrounded by a thick capsular polysaccharide that is a potent inhibitor of complement deposition via the alternative pathway. Several of its surface molecules can however activate the classical and lectin complement pathways, rendering this species still vulnerable to phagocytic killing. In this study we have identified a novel secreted protein named complement interfering protein (CIP) that downregulates complement activation via the classical and lectin pathways, but not the alternative pathway. The CIP protein showed high affinity toward C4b and inhibited its interaction with C2, presumably preventing the formation of the C4bC2a convertase. Addition of recombinant CIP to GBS cip-negative bacteria resulted in decreased deposition of C3b on their surface and in diminished phagocytic killing in a whole-blood assay. Our data reveal a novel strategy exploited by GBS to counteract innate immunity and could be valuable for the development of anti-infective agents against this important pathogen. PMID:26608922

  20. The Group B Streptococcus-Secreted Protein CIP Interacts with C4, Preventing C3b Deposition via the Lectin and Classical Complement Pathways.

    PubMed

    Pietrocola, Giampiero; Rindi, Simonetta; Rosini, Roberto; Buccato, Scilla; Speziale, Pietro; Margarit, Immaculada

    2016-01-01

    The group B Streptococcus (GBS) is a leading cause of neonatal invasive disease. GBS bacteria are surrounded by a thick capsular polysaccharide that is a potent inhibitor of complement deposition via the alternative pathway. Several of its surface molecules can however activate the classical and lectin complement pathways, rendering this species still vulnerable to phagocytic killing. In this study we have identified a novel secreted protein named complement interfering protein (CIP) that downregulates complement activation via the classical and lectin pathways, but not the alternative pathway. The CIP protein showed high affinity toward C4b and inhibited its interaction with C2, presumably preventing the formation of the C4bC2a convertase. Addition of recombinant CIP to GBS cip-negative bacteria resulted in decreased deposition of C3b on their surface and in diminished phagocytic killing in a whole-blood assay. Our data reveal a novel strategy exploited by GBS to counteract innate immunity and could be valuable for the development of anti-infective agents against this important pathogen. PMID:26608922

  1. Hemolytic complement activity and concentrations of its third component during maturation of the immune response in colostrum-deprived foals.

    PubMed

    Bernoco, M M; Liu, I K; Willits, N H

    1994-07-01

    Six foals were deprived of colostrum for the first 36 hours after birth and, instead, received reconstituted powdered milk. Five control foals suckled their dams naturally. Blood samples were obtained from all the foals after birth and at approximately weekly intervals until at least 5.5 months of age. Sera were analyzed for hemolytic complement activity, complement component C3, and correlating IgG concentration. Hemolytic complement (P = 0.0145) and C3 (P = 0.0002) values were significantly higher in colostrum-deprived foals (CDF) than in naturally nursed foals at 2 to 5 days of age. In addition, significantly (P = 0.0149) higher IgG concentration was found in CDF than in naturally nursed foals between 3 and 5.5 months of age. It was concluded that the observed high complement activity in CDF within 2 to 5 days of age may provide an alternative in immune defense for IgG-deprived foals after failure of colostral transfer. PMID:7978631

  2. IgG Suppresses Antibody Responses in Mice Lacking C1q, C3, Complement Receptors 1 and 2, or IgG Fc-Receptors

    PubMed Central

    Bergström, Joakim J. E.; Heyman, Birgitta

    2015-01-01

    Antigen-specific IgG antibodies, passively administered to mice or humans together with large particulate antigens like erythrocytes, can completely suppress the antibody response against the antigen. This is used clinically in Rhesus prophylaxis, where administration of IgG anti-RhD prevents RhD-negative women from becoming immunized against RhD-positive fetal erythrocytes aquired transplacentally. The mechanisms by which IgG suppresses antibody responses are poorly understood. We have here addressed whether complement or Fc-receptors for IgG (FcγRs) are required for IgG-mediated suppression. IgG, specific for sheep red blood cells (SRBC), was administered to mice together with SRBC and the antibody responses analyzed. IgG was able to suppress early IgM- as well as longterm IgG-responses in wildtype mice equally well as in mice lacking FcγRIIB (FcγRIIB knockout mice) or FcγRI, III, and IV (FcRγ knockout mice). Moreover, IgG was able to suppress early IgM responses equally well in mice lacking C1q (C1qA knockout mice), C3 (C3 knockout mice), or complement receptors 1 and 2 (Cr2 knockout mice) as in wildtype mice. Owing to the previously described severely impaired IgG responses in the complement deficient mice, it was difficult to assess whether passively administered IgG further decreased their IgG response. In conclusion, Fc-receptor binding or complement-activation by IgG does not seem to be required for its ability to suppress antibody responses to xenogeneic erythrocytes. PMID:26619292

  3. Serum Complement C3f and Fibrinopeptide A Are Potential Novel Diagnostic Biomarkers for Non-Alcoholic Fatty Liver Disease: A Study in Qingdao Twins

    PubMed Central

    Lin, Zhong-Hua; Cui, Ya-Zhou; Duan, Hai-Ping; Zhang, Mei; Xuan, Shi-Ying

    2014-01-01

    Aims To compare the different serum peptidome patterns between twins with and without non-alcoholic fatty liver disease (NAFLD) in order to help understand the pathogenesis of NAFLD and to identify potential diagnostic and therapeutic targets. Methods The peptidomics patterns of 63 cases with NAFLD were compared with their twin healthy controls in Qingdao, China. Peptides between 800Da and 3500Da were captured and concentrated using C18 reversed-phase columns, followed by MALDI-TOF mass spectrometry. The sequences of peptides associated with NAFLD were further identified by MALDI-TOF-TOF. Further validation studies were conducted. One hundred additional serum samples were detected by commercially available ELISA kits to calculate the concentrations of complement C3f and fibrinopeptide A, respectively. The differences of these two peptides in the NAFLD and control groups were compared using SPSS 17.0, respectively. Results Compared with healthy controls, eleven peaks (861.1, 877.07, 904.5, 1206.57, 1350.64, 1518.7, 1690.9, 1777.94, 2931.29, 3190.4, 3261.4) were up-regulated and 7 peaks (942.44, 1020.47, 1060.06, 1211.7, 1263.63, 1449.76, 2768.3) were down-regulated in the NAFLD group. Two peptides derived from complement C3f and fibrinopeptide A, respectively, had the highest ROC values indistinguishing NAFLD cases from their normal controls. In the validation group, the concentrations of complement C3f and fibrinopeptide A (1466.929±78.306 pg/ml, 4.189±0.326 ng/ml, respevtively) in NAFLD group was higher than in control group (complement C3f 1159.357±99.624 pg/ml, FPA 3.039±0.483 ng/ml; P<0.05). Conclusions In this study, we established apeptidomics pattern that could help distinguish NAFLD patients from their twin controls. The differently-regulated peptides identified in our study may be potential diagnostic markers or therapeutic targets for NAFLD. PMID:25250770

  4. Complement factor H allotype 402H is associated with increased C3b opsonization and phagocytosis of Streptococcus pyogenes.

    PubMed

    Haapasalo, Karita; Jarva, Hanna; Siljander, Tuula; Tewodros, Wezenet; Vuopio-Varkila, Jaana; Jokiranta, T Sakari

    2008-11-01

    The main virulence factor of group A streptococcus (GAS), M protein, binds plasma complement regulators factor H (FH) and FH-like protein 1 (FHL-1) leading to decreased opsonization. The M protein binding site on FH is within domain 7 in which also the age-related macular degeneration (AMD)-associated polymorphism Y402H is located. We studied if FH allotypes 402H and 402Y have different binding affinities to GAS. Plasma-derived FH allotype 402H and its recombinant fragment FH5-7(402H) showed decreased binding to several GAS strains. Growth of GAS in human blood taken from FH(402H) homozygous individuals was decreased when compared with blood taken from FH(402Y) homozygous individuals. The effect of the allotype 402H can be explained by combining the previous M protein mutagenesis data and the recently published crystal structure of FH6-8. In conclusion the data indicate that the AMD-associated allotype 402H leads to diminished binding of FH to GAS and increased opsonophagocytosis of the bacteria in blood. These results suggest that the homozygous presence of the allele 402H could be associated with decreased risk for severe GAS infections offering an explanation for the high frequency of the allele despite its association with visual impairment. PMID:18627465

  5. M. leprae components induce nerve damage by complement activation: identification of lipoarabinomannan as the dominant complement activator.

    PubMed

    Bahia El Idrissi, Nawal; Das, Pranab K; Fluiter, Kees; Rosa, Patricia S; Vreijling, Jeroen; Troost, Dirk; Morgan, B Paul; Baas, Frank; Ramaglia, Valeria

    2015-05-01

    Peripheral nerve damage is the hallmark of leprosy pathology but its etiology is unclear. We previously identified the membrane attack complex (MAC) of the complement system as a key determinant of post-traumatic nerve damage and demonstrated that its inhibition is neuroprotective. Here, we determined the contribution of the MAC to nerve damage caused by Mycobacterium leprae and its components in mouse. Furthermore, we studied the association between MAC and the key M. leprae component lipoarabinomannan (LAM) in nerve biopsies of leprosy patients. Intraneural injections of M. leprae sonicate induced MAC deposition and pathological changes in the mouse nerve, whereas MAC inhibition preserved myelin and axons. Complement activation occurred mainly via the lectin pathway and the principal activator was LAM. In leprosy nerves, the extent of LAM and MAC immunoreactivity was robust and significantly higher in multibacillary compared to paucibacillary donors (p = 0.01 and p = 0.001, respectively), with a highly significant association between LAM and MAC in the diseased samples (r = 0.9601, p = 0.0001). Further, MAC co-localized with LAM on axons, pointing to a role for this M. leprae antigen in complement activation and nerve damage in leprosy. Our findings demonstrate that MAC contributes to nerve damage in a model of M. leprae-induced nerve injury and its inhibition is neuroprotective. In addition, our data identified LAM as the key pathogen associated molecule that activates complement and causes nerve damage. Taken together our data imply an important role of complement in nerve damage in leprosy and may inform the development of novel therapeutics for patients. PMID:25772973

  6. Complement modulatory activity of bisbenzylisoquinoline alkaloids isolated from Isopyrum thalictroides--II. Influence on C3-9 reactions in vitro and antiinflammatory effect in vivo.

    PubMed

    Ivanovska, N; Hristova, M; Philipov, S

    1999-05-01

    The main alkaloids isopyruthaline (It1), fangchinoline (It2) and isothalictrine (It3), isolated from Isopyrum thalictroides (L.) were investigated in complement-mediated reactions. The alkaloids influenced the alternative pathway (AP) activity in normal human serum (NHS). They enhanced the inhibitory action of complement activators--carrageenan (Car), zymosan (Zy), hydrogen peroxide (HP) and high temperature via classical pathway (CP) in NHS. Substances strongly potentiated the action of zymosan and cobra venom (CV) in guinea pig serum (GPS). It was established that they could provoke C3 conversion in NHS and mouse sera (MS). The antiinflammatory properties of the alkaloids were evaluated in mouse paw oedema induced by CV, Zy and histamine (His). Isopyruthaline and isothalictrine suppressed paw swelling in CV- and Zy-oedema. They were applied in Zy-induced multiple organ dysfunction syndrome (MODS) in mice. The alkaloids inhibited the increase of the serum complement activity provoked by the injection of zymosan. Itl lowered the mortality rate of mice with MODS if its application proceeded Zy. An increase of the number of mice without tissue injury was established after treatment with It1 and It3. PMID:10408630

  7. Complement activating factor(s) of Trypanosoma lewisi: some physiochemical characteristics of the active components.

    PubMed Central

    Nielsen, K; Sheppard, J; Tizard, I; Holmes, W

    1978-01-01

    Of the complement activating factors present in Trypanosoma lewisi, the major component, a carbohydrate containing substance was further investigated. This component was found to have a lag time of complete activation of 2 CH50 units of bovine complement of approximately 15 minutes while 1% trypsin (a known activator of complement, used as a control system) was capable of instant consumption of a similar quantity of complement. In addition, the complement activating factor of trypanosomes was observed to be stable at 100 degrees C for 15 minutes and over a pH range of 3.0 to 11.0. Thin layer chromatography studies suggested that at least part of the active component contained lipid, perhaps indicating that it may be glycolipid in nature. PMID:25701

  8. Increased leukotriene B(4) production, complement C3 conversion and acid hydrolase enzyme concentrations in different leucocyte sub-populations of dogs with atopic dermatitis.

    PubMed

    Breathnach, R; Donahy, C; Jones, B R; Bloomfield, F J

    2006-01-01

    Various markers of the inflammatory response were measured in peripheral blood mononuclear cells (PBMCs) and polymorphonuclear neutrophils (PMNs) from 31 dogs with atopic dermatitis (AD). The variables assayed included chemiluminescence, acid hydrolase enzyme concentrations, leukotriene B(4) (LTB(4)) production and complement C3 conversion. The results were compared to those derived from a population of clinically healthy dogs. Dogs with AD exhibited a significant increase in median LTB(4) production in PMNs compared to controls (0.94 versus 0.00 ng/10(6) cells; P<0.01). Significant increases in the median concentrations of intracellular beta-galactosidase (PBMC fraction - 0.42 versus 0.25 mU/10(6) cells; P<0.05) (PMN fraction - 0.47 versus 0.12 mU/10(6) cells; P<0.01) and beta-glucuronidase (PBMC fraction - 0.52 versus 0.27 mU/10(6) cells; P<0.05) were also evident in the AD group. Although median maximum chemiluminescence values for both leucocyte sub-populations were higher in controls, the differences recorded were not significant (P>0.05). However, the median time taken to reach maximum chemiluminescence was significantly shorter in the PMN fraction of dogs with AD (7.00 versus 10.00 min; P<0.01). Atopic dogs had a significant increase in the median percentage conversion of complement C3 to C3b (66.0 versus 57.3%; P<0.01). The results of this study indicate a priming of the inflammatory response in dogs with AD. The role of LTB(4) in the pathogenesis of canine AD and the potential efficacy of leukotriene antagonists in the treatment of this disorder warrant further investigation. PMID:16427587

  9. TNF Regulates Essential Alternative Complement Pathway Components and Impairs Activation of Protein C in Human Glomerular Endothelial Cells.

    PubMed

    Sartain, Sarah E; Turner, Nancy A; Moake, Joel L

    2016-01-15

    Atypical hemolytic uremic syndrome (aHUS) is a thrombotic microangiopathy with severe renal injury secondary to an overactive alternative complement pathway (AP). aHUS episodes are often initiated or recur during inflammation. We investigated gene expression of the surface complement regulatory proteins (CD55, CD59, CD46, and CD141 [thrombomodulin]) and AP components in human glomerular microvascular endothelial cells (GMVECs) and in HUVECs, a frequently used investigational model of endothelial cells. Surface complement regulatory proteins were also quantified by flow cytometry. All experiments were done with and without exposure to IL-1β or TNF. Without cytokine stimulation, we found that GMVECs had greater AP activation than did HUVECs. With TNF stimulation, THBD gene expression and corresponding CD141 surface presence in HUVECs and GMVECs were reduced, and gene expression of complement components C3 (C3) and factor B (CFB) was increased. Consequently, AP activation, measured by Ba production, was increased, and conversion of protein C (PC) to activated PC by CD141-bound thrombin was decreased, in GMVECs and HUVECs exposed to TNF. IL-1β had similar, albeit lesser, effects on HUVEC gene expression, and it only slightly affected GMVEC gene expression. To our knowledge, this is the first detailed study of the expression/display of AP components and surface regulatory proteins in GMVECs with and without cytokine stimulation. In aHUS patients with an underlying overactive AP, additional stimulation of the AP and inhibition of activated PC-mediated anticoagulation in GMVECs by the inflammatory cytokine TNF are likely to provoke episodes of renal failure. PMID:26673143

  10. Characterization of a Gene Coding for the Complement System Component FB from Loxosceles laeta Spider Venom Glands.

    PubMed

    Myamoto, Daniela Tiemi; Pidde-Queiroz, Giselle; Gonçalves-de-Andrade, Rute Maria; Pedroso, Aurélio; van den Berg, Carmen W; Tambourgi, Denise V

    2016-01-01

    The human complement system is composed of more than 30 proteins and many of these have conserved domains that allow tracing the phylogenetic evolution. The complement system seems to be initiated with the appearance of C3 and factor B (FB), the only components found in some protostomes and cnidarians, suggesting that the alternative pathway is the most ancient. Here, we present the characterization of an arachnid homologue of the human complement component FB from the spider Loxosceles laeta. This homologue, named Lox-FB, was identified from a total RNA L. laeta spider venom gland library and was amplified using RACE-PCR techniques and specific primers. Analysis of the deduced amino acid sequence and the domain structure showed significant similarity to the vertebrate and invertebrate FB/C2 family proteins. Lox-FB has a classical domain organization composed of a control complement protein domain (CCP), a von Willebrand Factor domain (vWFA), and a serine protease domain (SP). The amino acids involved in Mg2+ metal ion dependent adhesion site (MIDAS) found in the vWFA domain in the vertebrate C2/FB proteins are well conserved; however, the classic catalytic triad present in the serine protease domain is not conserved in Lox-FB. Similarity and phylogenetic analyses indicated that Lox-FB shares a major identity (43%) and has a close evolutionary relationship with the third isoform of FB-like protein (FB-3) from the jumping spider Hasarius adansoni belonging to the Family Salcitidae. PMID:26771533

  11. Characterization of a Gene Coding for the Complement System Component FB from Loxosceles laeta Spider Venom Glands

    PubMed Central

    Myamoto, Daniela Tiemi; Pidde-Queiroz, Giselle; Gonçalves-de-Andrade, Rute Maria; Pedroso, Aurélio; van den Berg, Carmen W.; Tambourgi, Denise V.

    2016-01-01

    The human complement system is composed of more than 30 proteins and many of these have conserved domains that allow tracing the phylogenetic evolution. The complement system seems to be initiated with the appearance of C3 and factor B (FB), the only components found in some protostomes and cnidarians, suggesting that the alternative pathway is the most ancient. Here, we present the characterization of an arachnid homologue of the human complement component FB from the spider Loxosceles laeta. This homologue, named Lox-FB, was identified from a total RNA L. laeta spider venom gland library and was amplified using RACE-PCR techniques and specific primers. Analysis of the deduced amino acid sequence and the domain structure showed significant similarity to the vertebrate and invertebrate FB/C2 family proteins. Lox-FB has a classical domain organization composed of a control complement protein domain (CCP), a von Willebrand Factor domain (vWFA), and a serine protease domain (SP). The amino acids involved in Mg2+ metal ion dependent adhesion site (MIDAS) found in the vWFA domain in the vertebrate C2/FB proteins are well conserved; however, the classic catalytic triad present in the serine protease domain is not conserved in Lox-FB. Similarity and phylogenetic analyses indicated that Lox-FB shares a major identity (43%) and has a close evolutionary relationship with the third isoform of FB-like protein (FB-3) from the jumping spider Hasarius adansoni belonging to the Family Salcitidae. PMID:26771533

  12. Identification and comparative analysis of complement C3-associated microRNAs in immune response of Apostichopus japonicus by high-throughput sequencing.

    PubMed

    Zhong, Lei; Zhang, Feng; Zhai, Yu; Cao, Yanhui; Zhang, Si; Chang, Yaqing

    2015-01-01

    MicroRNAs (miRNAs) are important effectors in mediating host-pathogen interaction. In this report, coelomocytes miRNA libraries of three Japanese sea cucumbers Apostichopus japonicus were built by Illumina(®) Hiseq2000 from different time points after lipopolysaccharide challenge (at time 0 h, 6 h and 12 h). The clean data received from high throughput sequencing were used to sequences analysis. Referenced to the Strongylocentrotus purpuratus genome, 38 conserved miRNAs were found, and three miRNA candidates were predicted by software. According to the evidence resulting from the expression of AjC3, expressing levels of spu-miR-133, spu-miR-137 and spu-miR-2004 altered along with the expression of AjC3 changing at different time points after LPS injection. Thus, we speculated that the three miRNAs may have influence on A. japonicus complement C3. The spu-miR-137 and miR-137 gene family in miRBase were analyzed by bioinformatics. There is an obvious discrepancy between invertebrates and vertebrates. The first and ninth nucleotides in invertebrate miR-137 are offset compared vertebrate miR-137. Importantly, this is the first attempt to map the stage of immune response regulome in echinoderms, which might be considered as information for elucidating the intrinsic mechanism underlying the immune system in this species. PMID:26634300

  13. Disease Recurrence After Early Discontinuation of Eculizumab in a Patient With Atypical Hemolytic Uremic Syndrome With Complement C3 I1157T Mutation.

    PubMed

    Toyoda, Hidemi; Wada, Hideo; Miyata, Toshiyuki; Amano, Keishiro; Kihira, Kentaro; Iwamoto, Shotaro; Hirayama, Masahiro; Komada, Yoshihiro

    2016-04-01

    Eculizumab, terminal complement inhibitor, has become the frontline treatment for atypical hemolytic uremic syndrome (aHUS). However, the optimal treatment schedule has not yet been established. We describe here an aHUS patient with a mutation of C3 I1157T who achieved remission with eculizumab and suffered a recurrence after eculizumab discontinuation, a clinical situation that has not been previously described in patients with C3 mutation. A 9-year-old male experienced an onset of aHUS after viral gastroenteritis and was treated with hemodialysis. At 13 years of age he developed bacterial enterocolitis due to Campylobacter jejuni and experienced a recurrence of aHUS. Eculizumab was initiated on day 4 after disease onset resulting in recovering laboratory parameters. The patient received eculizumab for 5 months before its discontinuation. Second relapse induced by bacterial pharyngitis was confirmed 4 months after eculizumab discontinuation and prompt eculizumab reinitiation resulted in rapid remission. The patients carrying mutations in CFH or C3 have a high frequency of relapse and worse prognosis. More than 50% of aHUS relapses occurred during the first year after the onset. Therefore, long-term treatment with eculizumab is appropriate in patients with aHUS who have experienced a relapse or have mutations associated with poor prognosis. PMID:26840081

  14. Identification and comparative analysis of complement C3-associated microRNAs in immune response of Apostichopus japonicus by high-throughput sequencing

    PubMed Central

    Zhong, Lei; Zhang, Feng; Zhai, Yu; Cao, Yanhui; Zhang, Si; Chang, Yaqing

    2015-01-01

    MicroRNAs (miRNAs) are important effectors in mediating host–pathogen interaction. In this report, coelomocytes miRNA libraries of three Japanese sea cucumbers Apostichopus japonicus were built by Illumina® Hiseq2000 from different time points after lipopolysaccharide challenge (at time 0 h, 6 h and 12 h). The clean data received from high throughput sequencing were used to sequences analysis. Referenced to the Strongylocentrotus purpuratus genome, 38 conserved miRNAs were found, and three miRNA candidates were predicted by software. According to the evidence resulting from the expression of AjC3, expressing levels of spu-miR-133, spu-miR-137 and spu-miR-2004 altered along with the expression of AjC3 changing at different time points after LPS injection. Thus, we speculated that the three miRNAs may have influence on A. japonicus complement C3. The spu-miR-137 and miR-137 gene family in miRBase were analyzed by bioinformatics. There is an obvious discrepancy between invertebrates and vertebrates. The first and ninth nucleotides in invertebrate miR-137 are offset compared vertebrate miR-137. Importantly, this is the first attempt to map the stage of immune response regulome in echinoderms, which might be considered as information for elucidating the intrinsic mechanism underlying the immune system in this species. PMID:26634300

  15. Epstein-Barr virus regulates activation and processing of the third component of complement.

    PubMed

    Mold, C; Bradt, B M; Nemerow, G R; Cooper, N R

    1988-09-01

    Serum incubated with purified EBV was found to contain C3 cleavage fragments characteristic of C3c. Since the cofactors necessary for such cleavage of C3b by factor I are not normally present in serum, EBV was tested for factor I cofactor activity. Purified EBV from both human and marmoset EBV-producing cell lines was found to act as a cofactor for the factor I-mediated breakdown C3b to iC3b and iC3b to C3c and C3dg. EBV also acted as a cofactor for the factor I-mediated cleavage of C4b to iC4b and iC4b to C4c and C4d. EBV from both the human and marmoset cell lines accelerated the decay of the alternative pathway C3 convertase. The classical pathway C3 convertase was unaffected. Multiple lines of evidence eliminated the possibility that marmoset or human CR1 was responsible for the functional activities of EBV preparations. The spectrum of activities was different from CR1 in that EBV and EBV-expressing cell lines failed to rosette with C3b or particles bearing C3b, the primary functional assay for CR1, and EBV did not accelerate classical pathway C3 convertase decay, another property of CR1. In addition, CR1 could not be detected immunologically on marmoset or human EBV-expressing cells and mAbs to CR1 failed to alter EBV-produced decay acceleration and factor I cofactor activities, although the antibodies blocked the same CR1-dependent functional activities. The multiple complement regulatory activities exhibited by purified EBV derived from human and marmoset cells differ from those of any of the known C3 or C4 regulatory proteins. These various activities would be anticipated to provide survival value for the virus by subverting complement- and cell-dependent host defense mechanisms. PMID:2844953

  16. Antagonism of the complement component C4 by flavivirus nonstructural protein NS1

    PubMed Central

    Avirutnan, Panisadee; Fuchs, Anja; Hauhart, Richard E.; Somnuke, Pawit; Youn, Soonjeon

    2010-01-01

    The complement system plays an essential protective role in the initial defense against many microorganisms. Flavivirus NS1 is a secreted nonstructural glycoprotein that accumulates in blood, is displayed on the surface of infected cells, and has been hypothesized to have immune evasion functions. Herein, we demonstrate that dengue virus (DENV), West Nile virus (WNV), and yellow fever virus (YFV) NS1 attenuate classical and lectin pathway activation by directly interacting with C4. Binding of NS1 to C4 reduced C4b deposition and C3 convertase (C4b2a) activity. Although NS1 bound C4b, it lacked intrinsic cofactor activity to degrade C4b, and did not block C3 convertase formation or accelerate decay of the C3 and C5 convertases. Instead, NS1 enhanced C4 cleavage by recruiting and activating the complement-specific protease C1s. By binding C1s and C4 in a complex, NS1 promotes efficient degradation of C4 to C4b. Through this mechanism, NS1 protects DENV from complement-dependent neutralization in solution. These studies define a novel immune evasion mechanism for restricting complement control of microbial infection. PMID:20308361

  17. Isolation of C4-binding protein from guinea pig plasma and demonstration of its function as a control protein of the classical complement pathway C3 convertase.

    PubMed

    Burge, J; Nicholson-Weller, A; Austen, K F

    1981-01-01

    A decay-accelerating factor of the classical complement pathway C3 convertase, C4b,2a, has been purified to homogeneity from guinea pig plasma by a 5-step procedure that includes 5% polyethyleneglycol-4000 (PEG-4000) precipitation, Sepharose 6B gel filtration, heparin-Sepharose chromatography, DE-52 anion exchange chromatography, and Sepharose-C4gp affinity chromatography. The protein elicited a monospecific antiserum in a rabbit and was found with the Mancini technique in both normal and C4-deficient guinea pig plasma at a concentration of 60 microgram/ml. The purified protein gave a single stained band of 550,000 m.w. on SDS-PAGE under nonreducing conditions and a single band of 72,000 m.w. with reduction and alkylation. On the basis of its m.w. and subunit structure, ability to bind to a C4 affinity column, and ability to regulate the classical C system by accelerating the decay of the classical C3 convertase this protein represents the guinea pig analog of the human C4-binding protein. PMID:6778916

  18. Amniotic Fluid Embolism Pathophysiology Suggests the New Diagnostic Armamentarium: β-Tryptase and Complement Fractions C3-C4 Are the Indispensable Working Tools

    PubMed Central

    Busardò, Francesco Paolo; Frati, Paola; Zaami, Simona; Fineschi, Vittorio

    2015-01-01

    Amniotic fluid embolism (AFE) is an uncommon obstetric condition involving pregnant women during labor or in the initial stages after delivery. Its incidence is estimated to be around 5.5 cases per 100,000 deliveries. Therefore, this paper investigated the pathophysiological mechanism, which underlies AFE, in order to evaluate the role of immune response in the development of this still enigmatic clinical entity. The following databases (from 1956 to September 2014) Medline, Cochrane Central, Scopus, Web of Science and Science Direct were used, searching the following key words: AFE, pathophysiology, immune/inflammatory response, complement and anaphylaxis. The main key word “AFE” was searched singularly and associated individually to each of the other keywords. Of the 146 sources found, only 19 were considered appropriate for the purpose of this paper. The clinical course is characterized by a rapid onset of symptoms, which include: acute hypotension and/or cardiac arrest, acute hypoxia (with dyspnoea, cyanosis and/or respiratory arrest), coagulopathies (disseminated intravascular coagulation and/or severe hemorrhage), coma and seizures. The pathology still determines a significant morbidity and mortality and potential permanent neurological sequelae for surviving patients. At this moment, numerous aspects involving the pathophysiology and clinical development are still not understood and several hypotheses have been formulated, in particular the possible role of anaphylaxis and complement. Moreover, the detection of serum tryptase and complement components and the evaluation of fetal antigens can explain several aspects of immune response. PMID:25807263

  19. Amniotic fluid embolism pathophysiology suggests the new diagnostic armamentarium: β-tryptase and complement fractions C3-C4 are the indispensable working tools.

    PubMed

    Busardò, Francesco Paolo; Frati, Paola; Zaami, Simona; Fineschi, Vittorio

    2015-01-01

    Amniotic fluid embolism (AFE) is an uncommon obstetric condition involving pregnant women during labor or in the initial stages after delivery. Its incidence is estimated to be around 5.5 cases per 100,000 deliveries. Therefore, this paper investigated the pathophysiological mechanism, which underlies AFE, in order to evaluate the role of immune response in the development of this still enigmatic clinical entity. The following databases (from 1956 to September 2014) Medline, Cochrane Central, Scopus, Web of Science and Science Direct were used, searching the following key words: AFE, pathophysiology, immune/inflammatory response, complement and anaphylaxis. The main key word "AFE" was searched singularly and associated individually to each of the other keywords. Of the 146 sources found, only 19 were considered appropriate for the purpose of this paper. The clinical course is characterized by a rapid onset of symptoms, which include: acute hypotension and/or cardiac arrest, acute hypoxia (with dyspnoea, cyanosis and/or respiratory arrest), coagulopathies (disseminated intravascular coagulation and/or severe hemorrhage), coma and seizures. The pathology still determines a significant morbidity and mortality and potential permanent neurological sequelae for surviving patients. At this moment, numerous aspects involving the pathophysiology and clinical development are still not understood and several hypotheses have been formulated, in particular the possible role of anaphylaxis and complement. Moreover, the detection of serum tryptase and complement components and the evaluation of fetal antigens can explain several aspects of immune response. PMID:25807263

  20. Studies on human blood lymphocytes with iC3b (type 3) complement receptors: III. Abnormalities in patients with active systemic lupus erythematosus.

    PubMed Central

    Gray, J D; Lash, A; Bakke, A C; Kitridou, R C; Horwitz, D A

    1987-01-01

    Lymphocytes displaying iC3b (Type 3) complement receptors (CR3) were quantified by flow cytometry in patients with systemic lupus erythematosus. The percentages and absolute numbers were compared to age and sex matched controls. Total CR3+ lymphocytes identified by the monoclonal antibodies OKM1 or Leu 15 were significantly decreased in patients with symptomatic arthritis, serositis or vasculitis and those with lupus nephritis, whereas values for CR3+ lymphocytes in patients with inactive disease were similar to normal donors. The phenotype of CR3+ lymphocytes was markedly different in patients with active SLE. In normals granular lymphocytes bearing Fc receptors for IgG (L cells) comprised two-thirds of CR3+ lymphocytes. However, in SLE this subset was reduced to 20% and there was a corresponding increase in CR3+ lymphocytes co-expressing the T3 marker. Percentages of CR3 T4+ but not CR3+ T8+ lymphocytes were significantly increased in SLE. Although patients with active disease were lymphopenic, absolute numbers of CR3+ lymphocytes co-expressing T cell markers were similar to normal controls. Since L cells are non-specific suppressors of Ig production, the reduction of this subset along with the increase in CR3 T4+ cells could contribute to unregulated antibody production characteristic of SLE. PMID:2955974

  1. Complement Test

    MedlinePlus

    ... helpful? Also known as: C1; C1q; C2; C3; C4; CH50; CH100 (among others) Formal name: Complement Activity; ... whether the system is functioning normally. C3 and C4 are the most frequently measured complement proteins. Total ...

  2. Complement component 3 interactions with coxsackievirus B3 capsid proteins: innate immunity and the rapid formation of splenic antiviral germinal centers.

    PubMed Central

    Anderson, D R; Carthy, C M; Wilson, J E; Yang, D; Devine, D V; McManus, B M

    1997-01-01

    Innate immunity is central to the clearance of pathogens from hosts as well as to the definition of acquired immune responses (D. T. Fearon, and R. M. Locksley, Science 272:50-53, 1996). Coxsackievirus B3 (CVB3), a human cardiopathic virus, was evaluated for the ability to activate the alternative and classical pathway of complement. CVB3 proteins interact with complement component 3 (C3, a soluble protein effector of innate immunity) after either in vitro exposure to mouse serum or in vivo murine infection and activate the alternative pathway of complement. In addition, we demonstrate that viral antigen retention and localization in germinal centers is dependent on C3, while virus antigen retention in extrafollicular regions in the spleen is not. In vivo depletion of native C3 abolished the rapid formation of virus-specific germinal centers (by day 3 post-CVB3 infection) in the absence of serum anti-CVB3 antibodies. These studies demonstrate that innate immune mechanisms, such as C3 interaction with CVB3, are essential for splenic antiviral germinal center formation in naive (antigen nonsensitized) mice resistant (C57BL/6J strain) and susceptible (A/J strain) to CVB3-induced myocarditis. PMID:9343244

  3. Deficiency of complement component 5 ameliorates glaucoma in DBA/2J mice

    PubMed Central

    2013-01-01

    Background Glaucoma is an age-related neurodegenerative disorder involving the loss of retinal ganglion cells (RGCs), which results in blindness. Studies in animal models have shown that activation of inflammatory processes occurs early in the disease. In particular, the complement cascade is activated very early in DBA/2J mice, a widely used mouse model of glaucoma. A comprehensive analysis of the role of the complement cascade in DBA/2J glaucoma has not been possible because DBA/2J mice are naturally deficient in complement component 5 (C5, also known as hemolytic complement, Hc), a key mediator of the downstream processes of the complement cascade, including the formation of the membrane attack complex. Methods To assess the role of C5 in DBA/2J glaucoma, we backcrossed a functional C5 gene from strain C57BL/6J to strain DBA/2J for at least 10 generations. The prevalence and severity of glaucoma was evaluated using ocular examinations, IOP measurements, and assessments of optic nerve damage and RGC degeneration. To understand how C5 affects glaucoma, C5 expression was assessed in the retinas and optic nerves of C5-sufficient DBA/2J mice, using immunofluorescence. Results C5-sufficient DBA/2J mice developed a more severe glaucoma at an earlier age than standard DBA/2J mice, which are therefore protected by C5 deficiency. Components of the membrane attack complex were found to be deposited at sites of axonal injury in the optic nerve head and associated with RGC soma in the retina. Conclusion C5 plays an important role in glaucoma, with its deficiency lessening disease severity. These results highlight the importance of fully understanding the role of the complement cascade in neurodegenerative diseases. Inhibiting C5 may be beneficial as a therapy for human glaucoma. PMID:23806181

  4. Systemic Lupus Erythematosus and Deficiencies of Early Components of the Complement Classical Pathway

    PubMed Central

    Macedo, Ana Catarina Lunz; Isaac, Lourdes

    2016-01-01

    The complement system plays an important role in the innate and acquired immune response against pathogens. It consists of more than 30 proteins found in soluble form or attached to cell membranes. Most complement proteins circulate in inactive forms and can be sequentially activated by the classical, alternative, or lectin pathways. Biological functions, such as opsonization, removal of apoptotic cells, adjuvant function, activation of B lymphocytes, degranulation of mast cells and basophils, and solubilization and clearance of immune complex and cell lysis, are dependent on complement activation. Although the activation of the complement system is important to avoid infections, it also can contribute to the inflammatory response triggered by immune complex deposition in tissues in autoimmune diseases. Paradoxically, the deficiency of early complement proteins from the classical pathway (CP) is strongly associated with development of systemic lupus erythematous (SLE) – mainly C1q deficiency (93%) and C4 deficiency (75%). The aim of this review is to focus on the deficiencies of early components of the CP (C1q, C1r, C1s, C4, and C2) proteins in SLE patients. PMID:26941740

  5. In vitro synthesis of immunoglobulins, secretory component and complement in normal and pathological skin and the adjacent mucous membranes

    PubMed Central

    Lai A Fat, R. F. M.; Suurmond, D.; Van Furth, R.

    1973-01-01

    A study on the synthesis of immunoglobulins (IgG, IgA, IgM, IgD, and IgE), secretory component and complement in normal and pathological skin and in the adjacent mucous membranes (i.e. conjunctiva, nasal, oral and vaginal mucosa) is reported. The results are based on the culture of tissue samples in a medium with two radioactive amino acids and the detection of synthesized proteins by autoradiography of the immunoelectrophoretic pattern of the culture fluid, except in the case of IgE for which the Ouchterlony technique was used. The results indicate that the normal skin does not synthesize immunoglobulins, whereas normal mucous membranes produce IgG and IgA. In the lesions of various skin diseases immunoglobulins are synthesized, mainly IgG but sometimes also IgA and IgE. The cells responsible for the production of immunoglobulins are plasma cells and lymphoid cells present in the skin lesions and mucous membranes. Synthesis of the free secretory component could be demonstrated only in certain mucous membranes (i.e. conjunctiva, nasal mucosa, and oral mucosa). Complement (C3) synthesis was found in normal skin, mucous membranes (i.e. conjunctiva, nasal and oral mucosa), and in the lesions of such skin diseases as discoid lupus erythematosus, (bullous) pemphigoid, dermatitis herpetiformis, malignant reticulosis, eczema and lichen planus. Complement production was also demonstrated in allergic skin reactions (i.e. tissue from allergic-positive patch tests, positive Mantoux tests and drug eruptions), but no immunoglobulin synthesis was detected in these lesions. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5 PMID:4199092

  6. Amastigotes of Trypanosoma cruzi escape destruction by the terminal complement components

    SciTech Connect

    Iida, K.; Whitlow, M.B.; Nussenzweig, V.

    1989-03-01

    We studied the effect of complement on two life cycle stages of the protozoan parasite Trypanosoma cruzi: epimastigotes, found in the insect vector, and amastigotes, found in the mammalian host. We found that while both stages activate vigorously the alternative pathway, only epimastigotes are destroyed. The amounts of C3 and C5b-7 deposited on the amastigotes were similar to those bound to the much larger epimastigotes. Binding of C9 to amastigotes was four to six times less than binding to epimastigotes, resulting in a lower C9/C5b-7 ratio. Although a fairly large amount of C9 bound stably to amastigotes, no functional channels were formed as measured by release of incorporated /sup 86/Rb. The bound C9 had the characteristic properties of poly-C9, that is, it expressed a neo-antigen unique to poly-C9, and migrated in SDS-PAGE with an apparent Mr greater than 10(5). The poly-C9 was removed from the surface of amastigotes by treatment with trypsin, indicating that it was not inserted in the lipid bilayer. Modification of amastigote surface by pronase treatment rendered the parasites susceptible to complement attack. These results suggest that amastigotes have a surface protein that binds to the C5b-9 complex and inhibits membrane insertion, thus protecting the parasites from complement-mediated lysis.

  7. Molecular cloning, characterization and expression analysis of the complement component C6 gene in grass carp.

    PubMed

    Shen, Yu-Bang; Zhang, Jun-Bin; Xu, Xiao-Yan; Li, Jia-Le

    2011-05-15

    The complement system, as a representative of innate immunity, plays a key role in the host defense against infections. C6 is the member of complement components creating the membrane attack complex (MAC). In this study, we cloned and characterized the grass carp complement component C6 (gcC6) gene. Our data showed that gcC6 gene contained a 2724bp open reading frame (ORF), a 237bp 5'-untranslated region (UTR) and a 219bp 3'-UTR. The deduced amino acid sequence of gcC6 showed 77.6% and 58.9% identity to zebrafish C6 and rainbow trout C6, respectively. GcC6 gene was expressed in a wide range of grass carp tissues, and the highest expression level of gcC6 was detected in the spleen and liver. Upon challenge with Aeromonas hydrophila, its expression was significantly up-regulated in muscle, trunk kidney, liver, head kidney, spleen, heart and intestine, whereas it was down-regulated in the brain and skin. The expression level of gcC6 was high at the unfertilized egg stage. It was significantly increased at 1 day post-hatching, but it was decreased at 10 days post-hatching. This result suggested that the complement C6 transcripts in early embryos were of maternal origin. PMID:21353312

  8. First principles study on the electronic structures and stability of Cr 7C 3 type multi-component carbides

    NASA Astrophysics Data System (ADS)

    Xiao, B.; Feng, J.; Zhou, C. T.; Xing, J. D.; Xie, X. J.; Chen, Y. H.

    2008-06-01

    First principles calculations were conducted to investigate the stabilities of six multi-component carbides of Cr 7C 3 by calculating the cohesive energy and formation enthalpy of them. The theoretical predictions were compared with the experimental results and they were in agreement with each other. The electronic structures of the six carbides were also calculated in order to provide more information about the relationship between the stability and crystal compositions at atomic scale.

  9. The Serum Complement System: A Simplified Laboratory Exercise to Measure the Activity of an Important Component of the Immune System

    ERIC Educational Resources Information Center

    Inglis, Jordan E.; Radziwon, Kimberly A.; Maniero, Gregory D.

    2008-01-01

    The immune system is a vital physiological component that affords animals protection from disease and is composed of innate and adaptive mechanisms that rely on cellular and dissolved components. The serum complement system is a series of dissolved proteins that protect against a variety of pathogens. The activity of complement in serum can be…

  10. Effect of complement and of the carbohydrate components of sputum on phagocytosis by human polymorphonuclear leucocytes

    PubMed Central

    Brogan, T. D.

    1964-01-01

    The phagocytic activity of human polymorphonuclear leucocyte preparations, which were free from plasma, has been estimated by direct determination under phase contrast of the number of living cells containing test particles. Spores of Aspergillus fumigatus were phagocytosed in the absence of added serum but phagocytosis of paraffin wax particles occurred only in the presence of serum containing the heat-labile and C′4 components of complement. In view of the unreactive nature of the paraffin hydrocarbons, it was considered unlikely that natural antibody played any part in the phenomenon. Although no phagocytosis of wax particles occurred in the absence of serum, almost 100 per cent of cells were phagocytic in preparations containing adequate concentrations of serum. It was therefore possible to determine the serum concentration necessary for 50 per cent of the polymorphs to phagocytose wax particles. By this means it was demonstrated that the addition of the carbohydrate components of sputum had a small but significant inhibitory effect on phagocytosis and that dextran had no such effect. The sputum mucoprotein depressed the complement titre of serum and this might have accounted for the reduction in the ability of a serum to promote phagocytosis when this complex was added. The sputum mucopolysaccharide had no such effect on the complement titre of serum and must have exerted its inhibitory action in some other way. ImagesFIG. 2 PMID:14239838

  11. C3 glomerulopathy: consensus report

    PubMed Central

    Pickering, Matthew C; D'Agati, Vivette D; Nester, Carla M; Smith, Richard J; Haas, Mark; Appel, Gerald B; Alpers, Charles E; Bajema, Ingeborg M; Bedrosian, Camille; Braun, Michael; Doyle, Mittie; Fakhouri, Fadi; Fervenza, Fernando C; Fogo, Agnes B; Frémeaux-Bacchi, Véronique; Gale, Daniel P; Goicoechea de Jorge, Elena; Griffin, Gene; Harris, Claire L; Holers, V Michael; Johnson, Sally; Lavin, Peter J; Medjeral-Thomas, Nicholas; Paul Morgan, B; Nast, Cynthia C; Noel, Laure-Hélène; Peters, D Keith; Rodríguez de Córdoba, Santiago; Servais, Aude; Sethi, Sanjeev; Song, Wen-Chao; Tamburini, Paul; Thurman, Joshua M; Zavros, Michael; Cook, H Terence

    2013-01-01

    C3 glomerulopathy is a recently introduced pathological entity whose original definition was glomerular pathology characterized by C3 accumulation with absent or scanty immunoglobulin deposition. In August 2012, an invited group of experts (comprising the authors of this document) in renal pathology, nephrology, complement biology, and complement therapeutics met to discuss C3 glomerulopathy in the first C3 Glomerulopathy Meeting. The objectives were to reach a consensus on: the definition of C3 glomerulopathy, appropriate complement investigations that should be performed in these patients, and how complement therapeutics should be explored in the condition. This meeting report represents the current consensus view of the group. PMID:24172683

  12. Lymphocyte receptors. I. Receptors for Fc of IgG and complement (C3b) on immunoglobulin-bearing, antigen-binding and antibody-secreting cells.

    PubMed Central

    McConnell, I; Hurd, C M

    1976-01-01

    Immunoglobulin (Ig) bearing, antigen-binding and antibody-secreting cells were investigated for the presence of membrane receptors for the Fc part of IgG and for C3b on their surface. Fc and C3b receptors were detected on the surface of most Ig-bearing and of most antigen-binding cells. Fc receptors were also detected on IgM antibody-secreting cells but not on IgG-secreting cells. C3b receptors were not detected on any antibody-secreting cells. These receptors are either lost from the B cell surface as they differentiate into antibody-secreting cells or are blocked in vivo by immune complexes or C3b. PMID:800392

  13. Heterocomplexes of Mannose-binding Lectin and the Pentraxins PTX3 or Serum Amyloid P Component Trigger Cross-activation of the Complement System*

    PubMed Central

    Ma, Ying Jie; Doni, Andrea; Skjoedt, Mikkel-Ole; Honoré, Christian; Arendrup, Maiken; Mantovani, Alberto; Garred, Peter

    2011-01-01

    The long pentraxin 3 (PTX3), serum amyloid P component (SAP), and C-reactive protein belong to the pentraxin family of pattern recognition molecules involved in tissue homeostasis and innate immunity. They interact with C1q from the classical complement pathway. Whether this also occurs via the analogous mannose-binding lectin (MBL) from the lectin complement pathway is unknown. Thus, we investigated the possible interaction between MBL and the pentraxins. We report that MBL bound PTX3 and SAP partly via its collagen-like domain but not C-reactive protein. MBL-PTX3 complex formation resulted in recruitment of C1q, but this was not seen for the MBL-SAP complex. However, both MBL-PTX3 and MBL-SAP complexes enhanced C4 and C3 deposition and opsonophagocytosis of Candida albicans by polymorphonuclear leukocytes. Interaction between MBL and PTX3 led to communication between the lectin and classical complement pathways via recruitment of C1q, whereas SAP-enhanced complement activation occurs via a hitherto unknown mechanism. Taken together, MBL-pentraxin heterocomplexes trigger cross-activation of the complement system. PMID:21106539

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

    PubMed Central

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

    2016-01-01

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

  15. C3 polymorphism in beta-thalassemia.

    PubMed

    Germenis, A; Kalantzi, M; Karamerou, A; Politi, C; Fertakis, A

    1984-01-01

    The distribution of phenotypes and gene frequencies of the third component of complement (C3) were studied in 106 beta-thalassemic patients and in 112 carriers of the beta-thalassemia trait. A statistically significant association was found between the C3F gene and homozygous beta-thalassemia. It can be suggested that this association may be related with the high incidence of infections encountered in these patients. PMID:6419525

  16. Role of complement component C1q in phagocytosis of Listeria monocytogenes by murine macrophage-like cell lines.

    PubMed Central

    Alvarez-Dominguez, C; Carrasco-Marin, E; Leyva-Cobian, F

    1993-01-01

    Listeria monocytogenes is a facultative intracellular pathogen of a great variety of cells. Among them, macrophages constitute the major effector cells of listerial immunity during the course of an infection. Although the molecular bases of L. monocytogenes attachment and entry to phagocytes are not completely understood, it has been demonstrated that C3b significantly increases L. monocytogenes uptake by macrophages via complement receptor type 3. The first component of complement, C1q, is present in organic fluids at a relatively high concentration, and C1q receptor sites in macrophages are also abundant. In the present report, results of studies on the role of C1q in the internalization and infectivity of L. monocytogenes by macrophages are presented. L. monocytogenes uptake is enhanced by prior treatment of bacteria with normal sera. Heated serum or C1q-deficient serum abrogates this enhancement. Purified C1q specifically restored uptake. This effect was blocked by the addition of F(ab')2 anti-C1q antibody but not by an irrelevant matched antibody. Direct binding of C1q to L. monocytogenes was specific, saturable, and dose dependent with both fluorescent and radiolabeled C1q. N-Acetyl-D-alanyl-L-isoglutamine, diaminopimelic acid, and L-rhamnose caused a significant dose-dependent inhibition of C1q binding to bacteria, suggesting that these molecules, at least, are involved in the attachment of C1q to L. monocytogenes cell wall. When C1q binding structures on macrophage-like cells were blocked with saturating concentrations of C1q, the uptake of C1q-opsonized bacteria was less than in untreated cells. These experiments demonstrate that, in addition to other reported mechanisms, L. monocytogenes binds C1q, which mediates enhanced uptake by macrophages through C1q binding structures. Images PMID:8359889

  17. Trans complementation of virus-encoded replicase components of tobacco mosaic virus.

    PubMed

    Ogawa, T; Watanabe, Y; Meshi, T; Okada, Y

    1991-12-01

    We examined whether the 130K and 180K proteins of tobacco mosaic virus (TMV), the putative virus-encoded replicase components, produced by a replication-competent TMV mutant could complement a replication-defective mutant in a single cell. The replication-competent mutant (LDCS29) had a deletion in the coat protein gene and the replication-defective mutant (LDR28) had a large deletion in the gene encoding the 130K and 180K proteins. Neither the replication of LDR28 nor the production of the coat protein from LDR28 or LDCS29 was detected when the mutants were inoculated separately into tobacco protoplasts. However, when the two mutants were co-inoculated, the production of the LDR28 genomic RNA and the subgenomic RNA for the coat protein and accumulation of the coat protein were observed. These results show that the virus-encoded replicase components of TMV complemented the replication-defective mutant in trans. PMID:1962439

  18. Complement Receptor 3 Binds the Borrelia burgdorferi Outer Surface Proteins OspA and OspB in an iC3b-Independent Manner

    PubMed Central

    Garcia, Rodolfo C.; Murgia, Rossella; Cinco, Marina

    2005-01-01

    Persistence of borreliae within the vertebrate host depends on the fate of interactions between the spirochetes and target cells. The present work demonstrates the direct binding of the Borrelia burgdorferi outer surface proteins OspA and OspB to CR3 and that this binding is independent of iC3b. PMID:16113335

  19. The Complement Component 5 gene and Age-related Macular Degeneration

    PubMed Central

    Baas, Dominique C.; Ho, Lintje; Ennis, Sarah; Merriam, Joanna E.; Tanck, Michael W.T.; Uitterlinden, André G.; de Jong, Paulus T.V.M.; Cree, Angela J.; Griffiths, Helen L.; Rivadeneira, Fernando; Hofman, Albert; van Duijn, Cornelia; Smith, R. Theodore; Barile, Gaetano R.; Gorgels, Theo G.M.F.; Vingerling, Johannes R.; Klaver, Caroline C.W.; Lotery, Andrew J.; Allikmets, Rando; Bergen, Arthur A.B.

    2009-01-01

    Objective To investigate the association between variants in the complement component 5 (C5) gene and age-related macular degeneration (AMD). Design Separate and combined data from three large AMD case-control studies and a prospective population-based study (The Rotterdam Study). Participants A total of 2599 AMD cases and 3458 ethnically matched controls. Methods Fifteen single nucleotide polymorphisms (SNPs) spanning the C5 gene were initially genotyped in 375 cases and 199 controls from the Netherlands (The AMRO-NL study population). Replication testing of selected SNPs was performed in the Rotterdam Study (NL) and study populations from Southampton, United Kingdom (UK) and New York, United States (US). Main Outcome Measures Early and late stages of prevalent and incident AMD, graded according to (a modification of) the international grading and classification system of AMD. Results Significant allelic or genotypic associations between eight C5 SNPs and AMD were found in the AMRO-NL study and this risk appeared independently of CFH Y402H, LOC387715 A69S, age and gender. None of these findings could be confirmed consistently in three replication populations. Conclusions Although the complement pathway, including C5, plays a crucial role in AMD, and the C5 protein is present in drusen, no consistent significant associations between C5 SNPs and AMD were found in all studies. The implications for genetic screening of AMD are discussed. PMID:20022638

  20. Structure of the poly-C9 component of the complement membrane attack complex

    NASA Astrophysics Data System (ADS)

    Dudkina, Natalya V.; Spicer, Bradley A.; Reboul, Cyril F.; Conroy, Paul J.; Lukoyanova, Natalya; Elmlund, Hans; Law, Ruby H. P.; Ekkel, Susan M.; Kondos, Stephanie C.; Goode, Robert J. A.; Ramm, Georg; Whisstock, James C.; Saibil, Helen R.; Dunstone, Michelle A.

    2016-02-01

    The membrane attack complex (MAC)/perforin-like protein complement component 9 (C9) is the major component of the MAC, a multi-protein complex that forms pores in the membrane of target pathogens. In contrast to homologous proteins such as perforin and the cholesterol-dependent cytolysins (CDCs), all of which require the membrane for oligomerisation, C9 assembles directly onto the nascent MAC from solution. However, the molecular mechanism of MAC assembly remains to be understood. Here we present the 8 Å cryo-EM structure of a soluble form of the poly-C9 component of the MAC. These data reveal a 22-fold symmetrical arrangement of C9 molecules that yield an 88-strand pore-forming β-barrel. The N-terminal thrombospondin-1 (TSP1) domain forms an unexpectedly extensive part of the oligomerisation interface, thus likely facilitating solution-based assembly. These TSP1 interactions may also explain how additional C9 subunits can be recruited to the growing MAC subsequent to membrane insertion.

  1. Structure of the poly-C9 component of the complement membrane attack complex

    PubMed Central

    Dudkina, Natalya V.; Spicer, Bradley A.; Reboul, Cyril F.; Conroy, Paul J.; Lukoyanova, Natalya; Elmlund, Hans; Law, Ruby H. P.; Ekkel, Susan M.; Kondos, Stephanie C.; Goode, Robert J. A.; Ramm, Georg; Whisstock, James C.; Saibil, Helen R.; Dunstone, Michelle A.

    2016-01-01

    The membrane attack complex (MAC)/perforin-like protein complement component 9 (C9) is the major component of the MAC, a multi-protein complex that forms pores in the membrane of target pathogens. In contrast to homologous proteins such as perforin and the cholesterol-dependent cytolysins (CDCs), all of which require the membrane for oligomerisation, C9 assembles directly onto the nascent MAC from solution. However, the molecular mechanism of MAC assembly remains to be understood. Here we present the 8 Å cryo-EM structure of a soluble form of the poly-C9 component of the MAC. These data reveal a 22-fold symmetrical arrangement of C9 molecules that yield an 88-strand pore-forming β-barrel. The N-terminal thrombospondin-1 (TSP1) domain forms an unexpectedly extensive part of the oligomerisation interface, thus likely facilitating solution-based assembly. These TSP1 interactions may also explain how additional C9 subunits can be recruited to the growing MAC subsequent to membrane insertion. PMID:26841934

  2. Soluble form of complement C3b/C4b receptor (CR1) results from a proteolytic cleavage in the C-terminal region of CR1 transmembrane domain.

    PubMed Central

    Hamer, I; Paccaud, J P; Belin, D; Maeder, C; Carpentier, J L

    1998-01-01

    The complement C3b/C4b receptor (CR1) is an integral protein, anchored in the plasma membrane through a hydrophobic domain of 25 amino acids, but is also found in the plasma in soluble form (sCR1). A recombinant, soluble form of CR1 has been demonstrated to reduce complement-dependent tissue injury in animal models of ischaemia/reperfusion. In view of the important pathophysiological relevance of sCR1, we have investigated the mechanisms governing CR1 release by using various mutated and chimaeric receptors transiently expressed in COS cells. Pulse-chase experiments revealed that (1) sCR1 is produced by a proteolytic process, (2) the cleavage site lies within the C-terminus of CR1 transmembrane domain, (3) the proteolytic process involves a fully glycosylated CR1 form and (4) this process takes place in late secretory vesicles or at the plasma membrane. PMID:9405292

  3. Genetic association of complement component 2 polymorphism with systemic lupus erythematosus.

    PubMed

    Chen, H-H; Tsai, L-J; Lee, K-R; Chen, Y-M; Hung, W-T; Chen, D-Y

    2015-08-01

    Complement component 2 (C2), an early member of the classical pathway, mainly participates in apoptotic cell clearance. We hypothesize that C2 polymorphism may confer genetic susceptibility to complement dysfunction in systemic lupus erythematosus (SLE). The major aim of our study was to investigate the clinical and serological associations of C2 variants in Chinese patients with SLE. The single-nucleotide polymorphism (rs2844455, G/A SNP) located in the intron region of C2 gene was genotyped by direct sequencing in 95 SLE patients and 95 matched normal control subjects. The gene expression profiles were generated by quantitative real-time polymerase chain reaction (PCR) and reverse transcription PCR. Our results showed that the AA genotype was observed more frequently in SLE patients than in normal control subjects (22.1% vs 9.5%, P < 0.05). The A allele was strongly associated with the occurrence of hair loss, photosensitivity and anti-cardiolipin antibodies; whereas, the G allele was associated with lower frequencies of these clinical presentations. Relative expression levels were significantly lower in patients with the AA genotype [median: 18.86, interquartile range (IQR) 11.36-22.43, P = 0.002] than in those with the GG genotype (35.76, IQR: 19.33-49.71). As expected, we confirmed the A allele as a risk factor for SLE development in a Chinese population, in contrast, the G allele might be a protective factor against the pathogenic autoantibody formation and cutaneous manifestations in SLE patients. PMID:26176736

  4. C1q component of complement binds to fibrinogen and fibrin

    SciTech Connect

    Entwistle, R.A.; Furcht, L.T.

    1988-01-12

    The interaction of complement component C1q with fibrinogen and fibrin was studied by using a solid-phase direct binding assay. Scatchard analysis of radioiodinated fibrinogen binding to C1q indicated at least two high-affinity binding constants (Kd) calculated as 8.5 and 120 nM. In contrast, binding of radioiodinated fibrin to C1q showed only a single class of binding sites with a calculated Kd of 600 nM. Fibrinogen-C1q binding was shown to decrease as a function of increasing salt concentrations, indicating either the presence of charged amino acids in the binding sites or an ionic strength induced conformational dependency of the binding. In direct binding studies using isolated fragments of C1q, both the collagen-like domain of C1q and the globular domains of C1q were shown to bind fibrinogen, indicating at least one binding site for fibrinogen is located in each of the major domains of C1q. Addition of the thrombin-generated peptides of fibrinogen, fibrinopeptides A and B, enhanced C1q-fibrinogen binding, again indicating a complex binding interaction. These results indicate that C1q and fibrinogen are capable of high-affinity interactions that may serve to sequester these complexes in areas of tumors, immune complex deposition, or wounds.

  5. Relationship between the gene and protein structure in human complement component C9

    SciTech Connect

    Marazziti, D.; Eggertsen, G.; Fey, G.H.; Stanley, K.K.

    1988-08-23

    Human complement component C9 is a multidomain protein for which a large number of surface topographical features have been determined. The authors have analyzed the exon-intron boundaries of the human C9 gene and find a good correlation between splice sites and surface feature of the protein but little correlation with a putative protein domain structure, even in the cysteine-rich sequence homology with the low-density lipoprotein (LDL) receptor which is likely to be an independently folded structural motif. This is surprising because in the LDL receptor the same sequence is precisely bounded by introns, and it has been assumed that this sequence is present in both proteins as a result of exon shuffling. They deduce that substantial rearrangement of the exon-intron structure of the C9 gene must have occurred before the exchange of cysteine-rich domains, possibly linked to the process of exon duplication which was required to generate the repeats in the LDL receptor.

  6. The intricate role of complement component C4 in human systemic lupus erythematosus.

    PubMed

    Yang, Yan; Chung, Erwin K; Zhou, Bi; Lhotta, Karl; Hebert, Lee A; Birmingham, Daniel J; Rovin, Brad H; Yu, C Yung

    2004-01-01

    It was observed about 50 years ago that low serum complement activity or low protein concentrations of complement C4 concurred with disease activities of systemic lupus erythematosus (SLE). Complete deficiencies of complement components C4A and C4B, albeit rare in human populations, are among the strongest genetic risk factors for SLE or lupus-like disease, across HLA haplotypes and racial backgrounds. However, whether heterozygous or partial deficiency of C4A (C4AQ0) or C4B (C4BQ0) is a predisposing factor for SLE has been a highly controversial topic. In this review we critically analyzed past epidemiologic studies on deficiency of C4A or C4B in human SLE. Cumulative results from more than 35 different studies revealed that heterozygous and homozygous deficiencies of C4A were present in 40-60% of SLE patients from almost all ethnic groups or races investigated, which included northern and central Europeans, Anglo-Saxons, Caucasians in the US, African Americans, Asian Chinese, Koreans and Japanese. In addition, French SLE and control populations had relatively low frequencies of C4AQ0, but the difference between the patient and control groups was statistically significant. The relative risk of C4AQ0 in SLE varied between 2.3 and 5.3 among different ethnic groups. In Caucasian and African SLE patients, the two major causes for C4AQ0 are (1) the presence of a mono-S RCCX (RP-C4-CYP21-TNX) module with a single, short C4B gene in the major histocompatibility complex; and (2) a 2-bp insertion into the sequence for codon 1213 at exon 29 of the mutant C4A gene. Both mono-S structures and 2-bp insertion in exon 29 are absent or extremely rare in the C4AQ0 of Oriental SLE patients. The highly significant association of C4AQ0 with SLE across multiple HLA haplotypes and ethnic groups, and the presence of different mechanisms leading to a C4A protein deficiency among SLE patients suggested that deficiency or low expression level of C4A protein is a primary risk factor for SLE

  7. Long-term sublingual immunotherapy for Japanese cedar pollinosis and the levels of IL-17A and complement components 3a and 5a.

    PubMed

    Sakashita, Masafumi; Yamada, Takechiyo; Imoto, Yoshimasa; Hirota, Tomomitsu; Tamari, Mayumi; Ito, Yumi; Kubo, Seita; Osawa, Yoko; Takahashi, Noboru; Fujieda, Shigeharu

    2015-09-01

    Allergen-specific immunotherapy is the only treatment that can alter the natural course of allergic disease. We performed long-term sublingual immunotherapy (SLIT) for patients with seasonal allergic rhinitis caused by Japanese cedar pollen (SAR-JCP), screened molecules as candidate biomarkers, and investigated serum IL-17A and complement components 3a (C3a) and C5a in order to evaluate whether these molecules show changes correlated to symptom scores. In this study, we found that the long-term SLIT reduced the serum levels of IL-17A and C3a and C5a. The levels of C3a in the patients significantly decreased from year 1 compared with those at the baseline, and their levels of IL-17A significantly decreased from year 2 compared with those at baseline. The levels of IL-17A, C3a, and C5a at year 4 of SLIT were significantly lower than not only those at baseline, but also those at year 1. A significant positive correlation was found between the symptom medication scores and the levels of IL-17A at year 4. The symptom medication scores in the group in which IL-17A levels decreased at year 4 were significantly lower than those in the group without such a decrease. The serum level of IL-17A might prove useful as a biological parameter to ascertain the effectiveness of SLIT for patients with SAR-JCP. It is necessary to produce new therapeutics for non-responders in whom serum IL-17A levels are still higher against long-term SLIT. PMID:25934649

  8. Overview of C3 Glomerulopathy

    PubMed Central

    Master Sankar Raj, Vimal; Gordillo, Roberto; Chand, Deepa H.

    2016-01-01

    C3 glomerulopathy is an umbrella term, which includes several rare forms of glomerulonephritis (GN) with underlying defects in the alternate complement cascade. A common histological feature noted in all these GN is dominant C3 deposition in the glomerulus. In this review, we will provide an overview of the complement system as well as mediators, with an introduction to pharmaceutical agents that can alter the pathway. PMID:27200326

  9. Immune evasion of Enterococcus faecalis by an extracellular gelatinase that cleaves C3 and iC3b.

    PubMed

    Park, Shin Yong; Shin, Yong Pyo; Kim, Chong Han; Park, Ho Jin; Seong, Yeon Sun; Kim, Byung Sam; Seo, Sook Jae; Lee, In Hee

    2008-11-01

    Enterococcus faecalis (Ef) accounts for most cases of enterococcal bacteremia, which is one of the principal causes of nosocomial bloodstream infections (BSI). Among several virulence factors associated with the pathogenesis of Ef, an extracellular gelatinase (GelE) has been known to be the most common factor, although its virulence mechanisms, especially in association with human BSI, have yet to be demonstrated. In this study, we describe the complement resistance mechanism of Ef mediated by GelE. Using purified GelE, we determined that it cleaved the C3 occurring in human serum into a C3b-like molecule, which was inactivated rapidly via reaction with water. This C3 convertase-like activity of GelE was shown to result in a consumption of C3 and thus inhibited the activation of the complement system. Also, GelE was confirmed to degrade an iC3b that was deposited on the Ag surfaces without affecting the bound C3b. This proteolytic effect of GelE against the major complement opsonin resulted in a substantial reduction in Ef phagocytosis by human polymorphonuclear leukocytes. In addition, we verified that the action of GelE against C3, which is a central component of the complement cascade, was human specific. Taken together, it was suggested that GelE may represent a promising molecule for targeting human BSI associated with Ef. PMID:18941224

  10. Complement fixation by rheumatoid factor.

    PubMed Central

    Tanimoto, K; Cooper, N R; Johnson, J S; Vaughan, J H

    1975-01-01

    The capacity for fixation and activation of hemolytic complement by polyclonal IgM rheumatoid factors (RF) isolated from sera of patients with rheumatoid arthritis and monoclonal IgM-RF isolated from the cryoprecipitates of patients with IgM-IgG mixed cryoglobulinemia was examined. RF mixed with aggregated, reduced, and alkylated human IgG (Agg-R/A-IgG) in the fluid phase failed to significantly reduce the level of total hemolytic complement, CH50, or of individual complement components, C1, C2, C3, and C5. However, sheep erythrocytes (SRC) coated with Agg-R/A-IgG or with reduced and alkylated rabbit IgG anti-SRC antibody were hemolyzed by complement in the presence of polyclonal IgM-RF. Human and guinea pig complement worked equally well. The degree of hemolysis was in direct proportion to the hemagglutination titer of the RF against the same coated cells. Monoclonal IgM-RF, normal human IgM, and purified Waldenström macroglobulins without antiglobulin activity were all inert. Hemolysis of coated SRC by RF and complement was inhibited by prior treatment of the complement source with chelating agents, hydrazine, cobra venom factor, specific antisera to C1q, CR, C5, C6, or C8, or by heating at 56 degrees C for 30 min. Purified radiolabeled C4, C3, and C8 included in the complement source were bound to hemolysed SRC in direct proportion to the degree of hemolysis. These data indicate that polyclonal IgM-RF fix and activate complement via the classic pathway. The system described for assessing complement fixation by isolated RF is readily adaptable to use with whole human serum. PMID:1078825

  11. Transcriptome Characterization by RNA-Seq Reveals the Involvement of the Complement Components in Noise-Traumatized Rat Cochleae

    PubMed Central

    Patel, Minal; Hu, Zihua; Bard, Jonathan; Jamison, Jennifer; Cai, Qunfeng; Hu, Bo Hua

    2013-01-01

    Acoustic trauma, a leading cause of sensorineural hearing loss in adults, induces a complex degenerative process in the cochlea. Although previous investigations have identified multiple stress pathways, a comprehensive analysis of cochlear responses to acoustic injury is still lacking. In the current study, we used the next-generation RNA-sequencing (RNA-seq) technique to sequence the whole transcriptome of the normal and noise-traumatized cochlear sensory epithelia (CSE). CSE tissues were collected from rat inner ears 1 d after the rats were exposed to a 120-dB (sound pressure level) noise for 2 h. The RNA-seq generated over 176 million sequence reads for the normal CSE and over 164 million reads for the noise-traumatized CSE. Alignment of these sequences with the rat Rn4 genome revealed the expression of over 17000 gene transcripts in the CSE, over 2000 of which were exclusively expressed in either the normal or noise-traumatized CSE. Seventy-eight gene transcripts were differentially expressed (70 upregulated and 8 downregulated) after acoustic trauma. Many of the differentially expressed genes are related to the innate immune system. Further expression analyses using qRT-PCR confirmed the constitutive expression of multiple complement genes in the normal organ of Corti and the changes in the expression levels of the complement factor I (Cfi) and complement component 1, s subcomponent (C1s) after acoustic trauma. Moreover, protein expression analysis revealed strong expression of Cfi and C1s proteins in the organ of Corti. Importantly, these proteins exhibited expression changes following acoustic trauma. Collectively, the results of the current investigation suggest the involvement of the complement components in cochlear responses to acoustic trauma. PMID:23727008

  12. Role of IgG and complement component C5 in the initial course of experimental cryptococcosis.

    PubMed Central

    Dromer, F; Perronne, C; Barge, J; Vilde, J L; Yeni, P

    1989-01-01

    Although cellular immunity has a crucial role during cryptococcosis, several in vitro studies have pointed out the importance of IgG anti-Cryptococcus neoformans antibodies and complement components during phagocytosis of the yeast by polymorphonuclear leucocytes and monocytes. We investigated the role of complement and specific antibodies in host defences against experimental cryptococcosis, using a monoclonal IgG1 antibody (E1) specific for cryptococcal capsular polysaccharide, and mice congenitally sufficient or deficient in the fifth component of complement (C5). During in vitro experiments, E1 and the normal mouse serum from C5-sufficient and -deficient mice were unable to inhibit the growth of C.neoformans. However, E1 was an efficient opsonin for the ingestion of C. neoformans by mouse peritoneal macrophages, acting in synergy with normal mouse serum. In vivo, E1 was protective in heavily infected C5-deficient mice (DBA/2) dying from an early acute pneumonia, but not in C5-sufficient mice (BALB/c) and in DBA/2 mice infected with a smaller inoculum dying from a late progressive meningo-encephalitis. Although protection against pneumonia is attributed to a local recruitment of phagocytes in C5-sufficient mice, this was not observed in C5-deficient mice protected with E1. In this case, IgG anti-C. neoformans antibodies seem to be an alternative for an efficient opsonization of the yeasts. Altogether, these data suggest that two main mechanisms may protect infected mice from an early fatal pneumonia: the efficient opsonization of the yeast by complement and the recruitment of phagocytes in infected tissues. PMID:2612053

  13. Molecules Great and Small: The Complement System.

    PubMed

    Mathern, Douglas R; Heeger, Peter S

    2015-09-01

    The complement cascade, traditionally considered an effector arm of innate immunity required for host defense against pathogens, is now recognized as a crucial pathogenic mediator of various kidney diseases. Complement components produced by the liver and circulating in the plasma undergo activation through the classical and/or mannose-binding lectin pathways to mediate anti-HLA antibody-initiated kidney transplant rejection and autoantibody-initiated GN, the latter including membranous glomerulopathy, antiglomerular basement membrane disease, and lupus nephritis. Inherited and/or acquired abnormalities of complement regulators, which requisitely limit restraint on alternative pathway complement activation, contribute to the pathogenesis of the C3 nephropathies and atypical hemolytic uremic syndrome. Increasing evidence links complement produced by endothelial cells and/or tubular cells to the pathogenesis of kidney ischemia-reperfusion injury and progressive kidney fibrosis. Data emerging since the mid-2000s additionally show that immune cells, including T cells and antigen-presenting cells, produce alternative pathway complement components during cognate interactions. The subsequent local complement activation yields production of the anaphylatoxins C3a and C5a, which bind to their respective receptors (C3aR and C5aR) on both partners to augment effector T-cell proliferation and survival, while simultaneously inhibiting regulatory T-cell induction and function. This immune cell-derived complement enhances pathogenic alloreactive T-cell immunity that results in transplant rejection and likely contributes to the pathogenesis of other T cell-mediated kidney diseases. C5a/C5aR ligations on neutrophils have additionally been shown to contribute to vascular inflammation in models of ANCA-mediated renal vasculitis. New translational immunology efforts along with the development of pharmacologic agents that block human complement components and receptors now permit

  14. Update on C3 glomerulopathy.

    PubMed

    Barbour, Thomas D; Ruseva, Marieta M; Pickering, Matthew C

    2016-05-01

    C3 glomerulopathy refers to a disease process in which abnormal control of complement activation, degradation or deposition results in predominant C3 fragment deposition within the glomerulus and glomerular damage. Recent studies have improved our understanding of its pathogenesis. The key abnormality is uncontrolled C3b amplification in the circulation and/or along the glomerular basement membrane. Family studies in which disease segregates with structurally abnormal complement factor H-related (CFHR) proteins demonstrate that abnormal CFHR proteins are important in some types of C3 glomerulopathy. This is currently thought to be due to the ability of these proteins to antagonize the major negative regulator of C3 activation, complement factor H (CFH), a process termed 'CFH de-regulation'. Recent clinicopathological cohort studies have led to further refinements in case definition, culminating in a 2013 consensus report, which provides recommendations regarding investigation and treatment. Early clinical experience with complement-targeted therapeutics, notably C5 inhibitors, has also now been published. Here, we summarize the latest developments in C3 glomerulopathy. PMID:25326473

  15. Update on C3 glomerulopathy

    PubMed Central

    Barbour, Thomas D.; Ruseva, Marieta M.; Pickering, Matthew C.

    2016-01-01

    C3 glomerulopathy refers to a disease process in which abnormal control of complement activation, degradation or deposition results in predominant C3 fragment deposition within the glomerulus and glomerular damage. Recent studies have improved our understanding of its pathogenesis. The key abnormality is uncontrolled C3b amplification in the circulation and/or along the glomerular basement membrane. Family studies in which disease segregates with structurally abnormal complement factor H-related (CFHR) proteins demonstrate that abnormal CFHR proteins are important in some types of C3 glomerulopathy. This is currently thought to be due to the ability of these proteins to antagonize the major negative regulator of C3 activation, complement factor H (CFH), a process termed ‘CFH de-regulation’. Recent clinicopathological cohort studies have led to further refinements in case definition, culminating in a 2013 consensus report, which provides recommendations regarding investigation and treatment. Early clinical experience with complement-targeted therapeutics, notably C5 inhibitors, has also now been published. Here, we summarize the latest developments in C3 glomerulopathy. PMID:25326473

  16. The Complement System in Schizophrenia

    PubMed Central

    Mayilyan, Karine R.; Weinberger, Daniel R.; Sim, Robert B.

    2009-01-01

    summary Several lines of evidence suggest that immunological factors contribute to schizophrenia. Since 1989, the role of complement, a major effector of innate immunity and an adjuvant of adaptive immunity, has been explored in schizophrenia. Increased activity of C1, C3, C4 complement components in schizophrenia has been reported by two or more groups. Two studies on different subject cohorts showed increased MBL-MASP-2 activity in patients versus controls. More then one report indicated a significant high frequency of FB*F allotype and low prevalence of the FS phenotype of complement factor B in schizophrenia. From the data reported, it is likely that the disorder is accompanied by alterations of the complement classical and lectin pathways, which undergo dynamic changes, depending on the illness course and the state of neuro-immune crosstalk. Recent findings, implicating complement in neurogenesis, synapse remodeling and pruning during brain development, suggest a reexamination of the potential role of complement in neurodevelopmental processes contributing to schizophrenia susceptibility. It is plausible that the multicomponent complement system has more than one dimensional association with schizophrenia susceptibility, pathopsychology and illness course, understanding of which will bring a new perspective for possible immunomodulation and immunocorrection of the disease. PMID:18560619

  17. Infectious diseases associated with complement deficiencies.

    PubMed Central

    Figueroa, J E; Densen, P

    1991-01-01

    The complement system consists of both plasma and membrane proteins. The former influence the inflammatory response, immune modulation, and host defense. The latter are complement receptors, which mediate the cellular effects of complement activation, and regulatory proteins, which protect host cells from complement-mediated injury. Complement activation occurs via either the classical or the alternative pathway, which converge at the level of C3 and share a sequence of terminal components. Four aspects of the complement cascade are critical to its function and regulation: (i) activation of the classical pathway, (ii) activation of the alternative pathway, (iii) C3 convertase formation and C3 deposition, and (iv) membrane attack complex assembly and insertion. In general, mechanisms evolved by pathogenic microbes to resist the effects of complement are targeted to these four steps. Because individual complement proteins subserve unique functional activities and are activated in a sequential manner, complement deficiency states are associated with predictable defects in complement-dependent functions. These deficiency states can be grouped by which of the above four mechanisms they disrupt. They are distinguished by unique epidemiologic, clinical, and microbiologic features and are most prevalent in patients with certain rheumatologic and infectious diseases. Ethnic background and the incidence of infection are important cofactors determining this prevalence. Although complement undoubtedly plays a role in host defense against many microbial pathogens, it appears most important in protection against encapsulated bacteria, especially Neisseria meningitidis but also Streptococcus pneumoniae, Haemophilus influenzae, and, to a lesser extent, Neisseria gonorrhoeae. The availability of effective polysaccharide vaccines and antibiotics provides an immunologic and chemotherapeutic rationale for preventing and treating infection in patients with these deficiencies. PMID

  18. Functional analysis of Cobra Venom Factor/human C3 chimeras transiently expressed in mammalian cells.

    PubMed

    Kölln, Johanna; Matzas, Mark; Jänner, Nathalie; Mix, Thorsten; Klensang, Katrin; Bredehorst, Reinhard; Spillner, Edzard

    2004-05-01

    The complement activating venom component Cobra Venom Factor (CVF), a functional and structural homologue of the human complement component C3, forms a stable CVF-dependent C3 convertase complex, which, in contrast to C3-dependent convertase effects continuous activation of the complement and, thereby, decomplementation. In order to elucidate the mechanism underlying the enhanced activity of CVF compared to human C3, we generated two CVF/C3 chimeras and established different affinity-based assay systems for functional analysis of these constructs. To allow for convenient expression and subsequent functional characterisation, the CVF/C3 chimeras as well as CVF and C3 were transiently expressed in mammalian cells. Problems due to the low concentration of the recombinant proteins in the supernatants of transient expressions were circumvented by fusion to peptide tags enabling their efficient immobilisation onto suitable surfaces and subsequent characterisation. In an alternative approach monoclonal antibody fragments generated from a semisynthetic phage display scFv library were employed for concentrating the recombinant proteins by immunoprecipitation. Utilising both approaches all transiently expressed proteins could be characterised for their complement consumption activity. The data obtained with the CVF/C3 chimeras demonstrate that the increased stability of the CVFBb complex is independent of the domains in CVF corresponding to binding sites of factor B and H and the cleavage sites of factor I in the human C3 molecule. PMID:15140572

  19. Netrin-1 Reduces Monocyte and Macrophage Chemotaxis towards the Complement Component C5a

    PubMed Central

    McCaffary, David; Iqbal, Asif Jilani; Greaves, David R.

    2016-01-01

    Netrin-1, acting at its cognate receptor UNC5b, has been previously demonstrated to inhibit CC chemokine-induced immune cell migration. In line with this, we found that netrin-1 was able to inhibit CCL2-induced migration of bone marrow derived macrophages (BMDMs). However, whether netrin-1 is capable of inhibiting chemotaxis to a broader range of chemoattractants remains largely unexplored. As our initial experiments demonstrated that RAW264.7 and BMDMs expressed high levels of C5a receptor 1 (C5aR1) on their surface, we aimed to determine the effect of netrin-1 exposure on monocyte/macrophage cell migration induced by C5a, a complement peptide that plays a major role in multiple inflammatory pathologies. Treatment of RAW264.7 macrophages, BMDMs and human monocytes with netrin-1 inhibited their chemotaxis towards C5a, as measured using two different real-time methods. This inhibitory effect was found to be dependent on netrin-1 receptor signalling, as an UNC5b blocking antibody was able to reverse netrin-1 inhibition of C5a induced BMDM migration. Treatment of BMDMs with netrin-1 had no effect on C5aR1 proximal signalling events, as surface C5aR1 expression, internalisation and intracellular Ca2+ release following C5aR1 ligation remained unaffected after netrin-1 exposure. We next examined receptor distal events that occur following C5aR1 activation, but found that netrin-1 was unable to inhibit C5a induced phosphorylation of ERK1/2, Akt and p38, pathways important for cellular migration. Furthermore, netrin-1 treatment had no effect on BMDM cytoskeletal rearrangement following C5a stimulation as determined by microscopy and real-time electrical impedance sensing. Taken together these data highlight that netrin-1 inhibits monocyte and macrophage cell migration, but that the mechanism behind this effect remains unresolved. Nevertheless, netrin-1 and its cognate receptors warrant further investigation as they may represent a potential avenue for the development of

  20. Netrin-1 Reduces Monocyte and Macrophage Chemotaxis towards the Complement Component C5a.

    PubMed

    Taylor, Lewis; Brodermann, Maximillian Hugo; McCaffary, David; Iqbal, Asif Jilani; Greaves, David R

    2016-01-01

    Netrin-1, acting at its cognate receptor UNC5b, has been previously demonstrated to inhibit CC chemokine-induced immune cell migration. In line with this, we found that netrin-1 was able to inhibit CCL2-induced migration of bone marrow derived macrophages (BMDMs). However, whether netrin-1 is capable of inhibiting chemotaxis to a broader range of chemoattractants remains largely unexplored. As our initial experiments demonstrated that RAW264.7 and BMDMs expressed high levels of C5a receptor 1 (C5aR1) on their surface, we aimed to determine the effect of netrin-1 exposure on monocyte/macrophage cell migration induced by C5a, a complement peptide that plays a major role in multiple inflammatory pathologies. Treatment of RAW264.7 macrophages, BMDMs and human monocytes with netrin-1 inhibited their chemotaxis towards C5a, as measured using two different real-time methods. This inhibitory effect was found to be dependent on netrin-1 receptor signalling, as an UNC5b blocking antibody was able to reverse netrin-1 inhibition of C5a induced BMDM migration. Treatment of BMDMs with netrin-1 had no effect on C5aR1 proximal signalling events, as surface C5aR1 expression, internalisation and intracellular Ca2+ release following C5aR1 ligation remained unaffected after netrin-1 exposure. We next examined receptor distal events that occur following C5aR1 activation, but found that netrin-1 was unable to inhibit C5a induced phosphorylation of ERK1/2, Akt and p38, pathways important for cellular migration. Furthermore, netrin-1 treatment had no effect on BMDM cytoskeletal rearrangement following C5a stimulation as determined by microscopy and real-time electrical impedance sensing. Taken together these data highlight that netrin-1 inhibits monocyte and macrophage cell migration, but that the mechanism behind this effect remains unresolved. Nevertheless, netrin-1 and its cognate receptors warrant further investigation as they may represent a potential avenue for the development of

  1. Inherited deficiency of second component of complement and HLA haplotype A10,B18 associated with inflammatory bowel disease.

    PubMed

    Slade, J D; Luskin, A T; Gewurz, H; Kraft, S C; Kirsner, J B; Zeitz, H J

    1978-06-01

    A patient with inflammatory bowel disease and sacroiliitis had haplotypes A10,B18 and Aw32,b18 at the major histocompatibility locus. Serum total complement and C2 hemolytic complement activities were undetectable; levels of the remaining C1-C9 components were normal. The parents, both siblings, and a child each had half-normal levels of C2 and either the A10,B18 or the Aw32,b18 hla haplotype. In a second unrelated family, an only child and both parents developed inflammatory bowel disease. The father and child had HLA haplotype A10,B18, but, along with the mother, each had normal serum levels of hemolytic C and C2. Homozygous C2 deficiency, often in association with the A10,B18 haplotype, has previously been linked with various autoimmune diseases and with propensity to infection. Our findings suggest that C2 deficiency or this haplotype also may predispose to inflammatory diseases of the intestine. PMID:666136

  2. Prosteatotic and Protective Components in a Unique Model of Fatty Liver: Gut Microbiota and Suppressed Complement System.

    PubMed

    Liu, Long; Zhao, Xing; Wang, Qian; Sun, Xiaoxian; Xia, Lili; Wang, Qianqian; Yang, Biao; Zhang, Yihui; Montgomery, Sean; Meng, He; Geng, Tuoyu; Gong, Daoqing

    2016-01-01

    Goose can develop severe hepatic steatosis without overt injury, thus it may serve as a unique model for uncovering how steatosis-related injury is prevented. To identify the markedly prosteatotic and protective mechanisms, we performed an integrated analysis of liver transcriptomes and gut microbial metagenomes using samples collected from overfed and normally-fed geese at different time points. The results indicated that the fatty liver transcriptome, initially featuring a 'metabolism' pathway, was later joined by 'cell growth and death' and 'immune diseases' pathways. Gut microbiota played a synergistic role in the liver response as microbial and hepatic genes affected by overfeeding shared multiple pathways. Remarkably, the complement system, an inflammatory component, was comprehensively suppressed in fatty liver, which was partially due to increased blood lactic acid from enriched Lactobacillus. Data from in vitro studies suggested that lactic acid suppressed TNFα via the HNF1α/C5 pathway. In conclusion, gut microbes and their hosts respond to excess energy influx as an organic whole, severe steatosis and related tolerance of goose liver may be partially attributable to gut microbiotic products and suppressed complement system, and lactic acid from gut microbiota participates in the suppression of hepatic TNFα/inflammation through the HNF1α/C5 pathway. PMID:27550859

  3. Prosteatotic and Protective Components in a Unique Model of Fatty Liver: Gut Microbiota and Suppressed Complement System

    PubMed Central

    Liu, Long; Zhao, Xing; Wang, Qian; Sun, Xiaoxian; Xia, Lili; Wang, Qianqian; Yang, Biao; Zhang, Yihui; Montgomery, Sean; Meng, He; Geng, Tuoyu; Gong, Daoqing

    2016-01-01

    Goose can develop severe hepatic steatosis without overt injury, thus it may serve as a unique model for uncovering how steatosis-related injury is prevented. To identify the markedly prosteatotic and protective mechanisms, we performed an integrated analysis of liver transcriptomes and gut microbial metagenomes using samples collected from overfed and normally-fed geese at different time points. The results indicated that the fatty liver transcriptome, initially featuring a ‘metabolism’ pathway, was later joined by ‘cell growth and death’ and ‘immune diseases’ pathways. Gut microbiota played a synergistic role in the liver response as microbial and hepatic genes affected by overfeeding shared multiple pathways. Remarkably, the complement system, an inflammatory component, was comprehensively suppressed in fatty liver, which was partially due to increased blood lactic acid from enriched Lactobacillus. Data from in vitro studies suggested that lactic acid suppressed TNFα via the HNF1α/C5 pathway. In conclusion, gut microbes and their hosts respond to excess energy influx as an organic whole, severe steatosis and related tolerance of goose liver may be partially attributable to gut microbiotic products and suppressed complement system, and lactic acid from gut microbiota participates in the suppression of hepatic TNFα/inflammation through the HNF1α/C5 pathway. PMID:27550859

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  5. Complement factor H related proteins (CFHRs).

    PubMed

    Skerka, Christine; Chen, Qian; Fremeaux-Bacchi, Veronique; Roumenina, Lubka T

    2013-12-15

    Factor H related proteins comprise a group of five plasma proteins: CFHR1, CFHR2, CFHR3, CFHR4 and CFHR5, and each member of this group binds to the central complement component C3b. Mutations, genetic deletions, duplications or rearrangements in the individual CFHR genes are associated with a number of diseases including atypical hemolytic uremic syndrome (aHUS), C3 glomerulopathies (C3 glomerulonephritis (C3GN), dense deposit disease (DDD) and CFHR5 nephropathy), IgA nephropathy, age related macular degeneration (AMD) and systemic lupus erythematosus (SLE). Although complement regulatory functions were attributed to most of the members of the CFHR protein family, the precise role of each CFHR protein in complement activation and the exact contribution to disease pathology is still unclear. Recent publications show that CFHR proteins form homo- as well as heterodimers. Genetic abnormalities within the CFHR gene locus can result in hybrid proteins with affected dimerization or recognition domains which cause defective functions. Here we summarize the recent data about CFHR genes and proteins in order to better understand the role of CFHR proteins in complement activation and in complement associated diseases. PMID:23830046

  6. Complement binding to Leishmania donovani promastigotes (LD)

    SciTech Connect

    Puentes, S.M.; Bates, P.A.; Dwyer, D.M.; Joiner, K.A.

    1986-03-01

    To study the binding and processing of C3 on LD, parasites in various phases of growth were incubated in human serum deficient in complement component 8 containing /sup 125/I-C3. Uptake of /sup 125/I-C3 is rapid, peaking at 1.7-2.1 x 10/sup 6/ C3 molecules bound per parasite at 15 minutes for all growth phases, and decreases thereafter with continued incubation. One half of total C3 bound is spontaneously released by 90 minutes of incubation with all LD phases and occurs at a similar rate for LD washed free of serum and incubated at 37/sup 0/ C in buffer. As assessed by SDS-PAGE autoradiography, C3 on the surface of LD is present as C3b (36 to 50%) and iC3b (50 to 65%), linked covalently via a bond resistant to hydroxylamine treatment, presumably an amide linkage. Immunoblot analysis of purified membranes from serum-incubated LD, using rabbit antibody to C3 and LD surface constituents, strongly suggests that a major C3 acceptor is the LD acid phosphatase (AP). These results, in conjunction with recent studies, suggest a previously unrecognized role of AP as a C3 acceptor and, thus, as a molecule potentially involved in parasite binding and uptake.

  7. Microglial activation and increased synthesis of complement component C1q precedes blood-brain barrier dysfunction in rats.

    PubMed

    Lynch, Nicholas J; Willis, Colin L; Nolan, Christopher C; Roscher, Silke; Fowler, Maxine J; Weihe, Eberhard; Ray, David E; Schwaeble, Wilhelm J

    2004-01-01

    A reliable way to visualise the state of microglial activation is to monitor the microglial gene expression profile. Microglia are the only CNS resident cells that synthesise C1q, the recognition sub-component of the classical complement pathway, in vivo. C1q biosynthesis in resting ramified microglia is often low, but it increases dramatically in activated microglia. In this study, the expression of C1q was used to monitor microglial activation at all stages of 3-chloropropanediol-induced neurotoxicity, a new model of blood-brain barrier (BBB) breakdown. In rats, 3-chloropropanediol produces very focused lesions in the brain, characterised by early astrocyte swelling and loss, followed by neuronal death and barrier dysfunction. Using in situ hybridisation, immunohistochemistry, and real-time RT-PCR, we found that increased C1q biosynthesis and microglial activation precede BBB dysfunction by at least 18 and peak 48 h after injection of 3-chloropropanediol, which coincides with the onset of active haemorrhage. Microglial activation is biphasic; an early phase of global activation is followed by a later phase in which microglial activation becomes increasingly focused in the lesions. During the early phase, expression of the pro-inflammatory mediators interleukin-1beta (IL1beta), tumour necrosis factor alpha (TNFalpha) and early growth response-1 (Egr-1) increased in parallel with C1q, but was restricted to the lesions. Expression of C1q (but not IL1beta, TNFalpha or Egr-1) remains high after BBB function is restored, and is accompanied by late up-regulation of the C1q-associated serine proteases, C1r and C1s, suggesting that microglial biosynthesis of the activation complex of the classical pathway may support the removal of cell debris by activation of complement. PMID:14644096

  8. High temperature stress and its effect on pollen development and morphological components of harvest index in the C3 model grass Brachypodium distachyon.

    PubMed

    Harsant, Jeffrey; Pavlovic, Lazar; Chiu, Greta; Sultmanis, Stefanie; Sage, Tammy L

    2013-07-01

    The effect of high temperatures on harvest index (HI) and morphological components that contribute to HI was investigated in two lines (Bd21 and Bd21-3) of Brachypodium distachyon, a C3 grass recognized as a tractable plant, to address critical issues associated with enhancing cereal crop yields in the presence of global climate change. The results demonstrated that temperatures ≥32 °C eliminated HI. Reductions in yield at 32 °C were due primarily to declines in pollen viability, retention of pollen in anthers, and pollen germination, while abortion of microspores by the uninucleate stage that was correlated with abnormal tapetal development resulted in yield failure at 36 °C. Increasing temperatures from 24 to 32 °C resulted in reductions in tiller numbers but had no impact on axillary branch numbers per tiller. Grain developed at 24 and 28 °C primarily in tiller spikes, although spikes on axillary branches also formed grain. Grain quantity decreased in tiller spikes but increased in axillary branch spikes as temperatures rose from 24 to 28 °C. Differential patterns of axillary branching and floret development within spikelets between Bd21 and Bd21-3 resulted in higher grain yield in axillary branches of Bd21-3 at 28 °C. The response of male reproductive development and tiller branching patterns in B. distachyon to increasing temperatures mirrors that in other cereal crops, providing support for the use of this C3 grass in assessing the molecular control of HI in the presence of global warming. PMID:23771979

  9. Effects of Streptococcus pneumoniae Strain Background on Complement Resistance

    PubMed Central

    Hyams, Catherine; Opel, Sophia; Hanage, William; Yuste, Jose; Bax, Katie; Henriques-Normark, Birgitta; Spratt, Brian G.; Brown, Jeremy S.

    2011-01-01

    Background Immunity to infections caused by Streptococcus pneumoniae is dependent on complement. There are wide variations in sensitivity to complement between S. pneumoniae strains that could affect their ability to cause invasive infections. Although capsular serotype is one important factor causing differences in complement resistance between strains, there is also considerable other genetic variation between S. pneumoniae strains that may affect complement-mediated immunity. We have therefore investigated whether genetically distinct S. pneumoniae strains with the same capsular serotype vary in their sensitivity to complement mediated immunity. Methodology and Principal Findings C3b/iC3b deposition and neutrophil association were measured using flow cytometry assays for S. pneumoniae strains with different genetic backgrounds for each of eight capsular serotypes. For some capsular serotypes there was marked variation in C3b/iC3b deposition between different strains that was independent of capsule thickness and correlated closely to susceptibility to neutrophil association. C3b/iC3b deposition results also correlated weakly with the degree of IgG binding to each strain. However, the binding of C1q (the first component of the classical pathway) correlated more closely with C3b/iC3b deposition, and large differences remained in complement sensitivity between strains with the same capsular serotype in sera in which IgG had been cleaved with IdeS. Conclusions These data demonstrate that bacterial factors independent of the capsule and recognition by IgG have strong effects on the susceptibility of S. pneumoniae to complement, and could therefore potentially account for some of the differences in virulence between strains. PMID:22022358

  10. Herpes simplex virus glycoprotein C: molecular mimicry of complement regulatory proteins by a viral protein.

    PubMed

    Huemer, H P; Wang, Y; Garred, P; Koistinen, V; Oppermann, S

    1993-08-01

    Herpes simplex virus (HSV) encodes a protein, glycoprotein C (gC), which binds to the third complement component, the central mediator of complement activation. In this study the structural and functional relationships of gC from HSV type 1 (HSV-1) and known human complement regulatory proteins factor H, properdin, factor B, complement receptor 1 (CR1) and 2 (CR2) were investigated. The interaction of gC with C3b was studied using purified complement components, synthetic peptides, antisera against different C3 fragments and anti-C3 monoclonal antibodies (mAb) with known inhibitory effects on C3-ligand interactions. All the mAb that inhibited gC/C3b interactions, in a differential manner, also prevented binding of C3 fragments to factors H, B, CR1 or CR2. No blocking was observed with synthetic peptides representing different C3 regions or with factor B and C3d, whereas C3b, C3c and factor H were inhibitory, as well as purified gC. There was no binding of gC to cobra venom factor (CVF), a C3c-like fragment derived from cobra gland. Purified gC bound to iC3, iC3b and C3c, but failed to bind to C3d. Glycoprotein C bound only weakly to iC3 derived from bovine and porcine plasma, thus indicating a preference of the viral protein for the appropriate host. Binding of gC was also observed to proteolytic C3 fragments, especially to the beta-chain, thus suggesting the importance of the C3 region as a binding site. Purified gC from HSV-1, but not HSV-2, inhibited the binding of factor H and properdin but not of CR1 to C3b. The binding of iC3b to CR2, a molecule involved in B-cell activation and binding of the Epstein-Barr virus, was also inhibited by the HSV-1 protein. As factor H and properdin, the binding of which was inhibited by gC, are important regulators of the alternative complement pathway, these data further support a role of gC in the evasion of HSV from a major first-line host defence mechanism, i.e. the complement system. In addition, the inhibition of the C3/CR

  11. [A case report of hereditary angioedema and studies on the serum components of complement, C1-inactivator and proteinase inhibitors during edema attack].

    PubMed

    Mikami, A; Kohno, M

    1987-05-01

    Sixteen years old girl was admitted because of for the past ten years' frequent edema attack and abdominal pain. Laboratory examination revealed hypocomplementemia, marked depletion of the fourth component of complement and low level of C1-inactivator. Familial studies revealed that her mother was also hypocomplementemic and in low level of C1-inactivator. Serial studies performed on the alterlation of components of complement, C1-inactivator, alpha 1-antitrypsin, antithrombin III, and alpha 2-macroglobulin during edema attack. The fourth component of complement and C1-inactivator were markedly depleted in remission and attack. Remarkable depletion was found in antithrombin III and esterase inhibition activity of C1-inactivator during attack. In contrast, alpha 1-antitrypsin and alpha 2-macroglobulin did not change. The present study may explain that Hageman factor fragments, activated by C1s, promotes kinin generation via kalikrein activation. And the condition that complete functional deficiency of C1-inactivator was main role in this circuit. Fibrynolysis and late components of complement was less influence on edema attack. PMID:3610041

  12. Complement system and immunological mediators: Their involvements in the induced inflammatory process by Androctonus australis hector venom and its toxic components.

    PubMed

    Bekkari, Nadjia; Martin-Eauclaire, Marie-France; Laraba-Djebari, Fatima

    2015-01-01

    Androctonus australis hector scorpion venom is well known by its high toxicity, it induces massive release of neurotransmitters that lead to pathophysiological disorders in cardiovascular, neuro-hormonal and immune systems. Previous studies have shown the relationship between the severity of scorpion envenoming and immune system activation. This study was assessed to investigate the involvement of complement system and inflammatory mediators after sublethal injection of Aah venom, its toxic fraction (FtoxG50) and its main toxins (AahI and AahII) into NMRI mice. The Activation complement system by the venom is also compared to that induced of lipopolysaccharides (LPS). Obtained results showed that seric complement system (CS) is activated by the venom and by its toxic components; this activation is more pronounced into liver tissue when toxic components (FtoxG50, AahI or AahII) are used. Increase of cytokine levels (IL1β, TNFα and ICAM) into hepatic tissue induced by AahI or AahII neurotoxins is correlated with tissue alterations. Aprotinin, a non specific inhibitor of complement system seems to be able to reduce CS consumption and to restore partially the induced tissue damage by venom. The mechanisms by which toxic fraction or LPS induced the activation of complement system seem to be different. Sensitivity of hepatic tissue is more pronounced after FtoxG50 injection; however lung tissue is more sensible to LPS than FoxG50. PMID:25921955

  13. Salivary agglutinin is the major component in human saliva that modulates the lectin pathway of the complement system.

    PubMed

    Gunput, Sabrina Tg; Wouters, Diana; Nazmi, Kamran; Cukkemane, Nivedita; Brouwer, Mieke; Veerman, Enno Ci; Ligtenberg, Antoon Jm

    2016-05-01

    Saliva interacts with blood after mucosal damage or leakage of gingival crevicular fluid. Surface-adsorbed salivary agglutinin (SAG) activates the lectin pathway (LP) of the complement system via mannose-binding lectin, while SAG in solution inhibits complement activation. In the present study we investigated if, next to SAG, whole and glandular saliva itself and other salivary glycoproteins activate or inhibit the LP. Complement activation was measured by detecting C4 deposition on microtiter plates coated with saliva or purified proteins. Complement inhibition was measured after incubating serum with saliva or proteins in microtiter plates coated with mannan, an LP activator. Adsorbed whole, sublingual and submandibular saliva showed LP-dependent complement activation. Blood group secretors, but not non-secretors, activated the LP. Saliva of both secretors and non-secretors inhibited C4 deposition on mannan. After depletion of SAG, saliva no longer inhibited the LP. Other salivary proteins, including amylase, MUC5B and histatin 2, did not activate or inhibit the LP. Surface-adsorbed whole saliva and glandular saliva samples activate the LP of complement, depending on the presence of SAG and the secretor status of the donor. In solution, saliva inhibits the LP, depending on the presence of SAG, but independent of the secretor status. PMID:27048414

  14. From orphan drugs to adopted therapies: Advancing C3-targeted intervention to the clinical stage.

    PubMed

    Mastellos, Dimitrios C; Reis, Edimara S; Yancopoulou, Despina; Hajishengallis, George; Ricklin, Daniel; Lambris, John D

    2016-10-01

    Complement dysregulation is increasingly recognized as an important pathogenic driver in a number of clinical disorders. Complement-triggered pathways intertwine with key inflammatory and tissue destructive processes that can either increase the risk of disease or exacerbate pathology in acute or chronic conditions. The launch of the first complement-targeted drugs in the clinic has undeniably stirred the field of complement therapeutic design, providing new insights into complement's contribution to disease pathogenesis and also helping to leverage a more personalized, comprehensive approach to patient management. In this regard, a rapidly expanding toolbox of complement therapeutics is being developed to address unmet clinical needs in several immune-mediated and inflammatory diseases. Elegant approaches employing both surface-directed and fluid-phase inhibitors have exploited diverse components of the complement cascade as putative points of therapeutic intervention. Targeting C3, the central hub of the system, has proven to be a promising strategy for developing biologics as well as small-molecule inhibitors with clinical potential. Complement modulation at the level of C3 has recently shown promise in preclinical primate models, opening up new avenues for therapeutic intervention in both acute and chronic indications fueled by uncontrolled C3 turnover. This review highlights recent developments in the field of complement therapeutics, focusing on C3-directed inhibitors and alternative pathway (AP) regulator-based approaches. Translational perspectives and considerations are discussed, particularly with regard to the structure-guided drug optimization and clinical advancement of a new generation of C3-targeted peptidic inhibitors. PMID:27353192

  15. Complement amplification revisited.

    PubMed

    Lutz, Hans U; Jelezarova, Emiliana

    2006-01-01

    Complement amplification in blood takes place not only on activating surfaces, but in plasma as well, where it is maintained primarily by C3b2-IgG complexes. Regular products of C3 activation in serum, these complexes are inherently very efficient precursors of the alternative pathway C3 convertase. Moreover, they can bind properdin bivalently, thus creating preferred sites for convertase formation. C3b2-IgG complexes have a half-life that is substantially longer than that of free C3b, since both C3b molecules are partially protected from inactivation by factor H and I. These complexes are preferentially generated on certain naturally occurring and induced antibodies that exhibit a paratope-independent affinity for C3/C3b. Such antibodies are known to stimulate alternative complement pathway activation. We have assembled the evidence for the generation and the functional potency of the C3b2-IgG complexes, which have been studied during the last two decades. We illustrate their roles in immune complex solubilization, phagocytosis, immune response, and their ability to initiate devastating effects in ischemia/reperfusion and in aggravating inflammation. PMID:16023211

  16. Intracellular Complement Activation Sustains T Cell Homeostasis and Mediates Effector Differentiation

    PubMed Central

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

    2013-01-01

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

  17. Intracellular complement activation sustains T cell homeostasis and mediates effector differentiation.

    PubMed

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

    2013-12-12

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

  18. Monoclonal antibody OKB7, which identifies the 14OKd complement receptor type 2 (CR/sub 2/), also identifies a 72Kd secreted fragment of CR/sub 2/ that contains the C3d-binding site

    SciTech Connect

    Myones, B.L.; Ross, G.D.

    1986-03-05

    CR/sub 2/ is a 140-145Kd glycoprotein expressed on B lymphocytes which binds both C3d and Epstein-Barr virus (EBV). OKB7, an IgG/sub 2a/ monoclonal antibody to CR/sub 2/, blocks C3d and EBV binding, while HB-5, another monoclonal IgG/sub 2a/ anti-CR/sub 2/, does not. A 72Kd C3d-binding glycoprotein (gp72), isolated from Raji cell media, was previously thought to be CR/sub 2/ because a polyclonal rabbit anti-gp72 inhibited EC3d rosettes. ELISA assay demonstrated that OKB7, but not HB-5, bound to purified gp72 fixed to microtiter wells. Insoluble and soluble gp72 blocked Raji cell uptake of /sup 125/I-labeled OKB7, but not labeled anti-B2 or HB-5. Rabbit anti-gp72 immunoprecipitated bands at 140Kd and 72Kd from /sup 125/I-labelled and solubilized B cell membranes. Culture media from Raji cells grown in the presence /sup 3/H-labeled amino acids was sequentially immunoprecipitated by irrelevant antibody, OKB7, and HB-5. A single 72Kd radiolabeled band was demonstrated only with OKB7, and this was identical to that produced by the immunoprecipitation of /sup 125/I-labeled gp72 with rabbit anti-gp72. Thus, OKB7, which identifies the 140Kd CR/sub 2/ molecule, also identifies a 72Kd shed fragment of CR/sub 2/ isolated from Raji cell media, which contains the C3d-binding site.

  19. C3 Polymorphism Influences Circulating Levels of C3, ASP and Lipids in Schizophrenic Patients.

    PubMed

    Nsaiba, Mohamed Jalloul; Lapointe, Marc; Mabrouk, Hajer; Douki, Wahiba; Gaha, Lotfi; Pérusse, Louis; Bouchard, Claude; Jrad, Besma Bel Hadj; Cianflone, Katherine

    2015-05-01

    Excessive activation of complement is associated with many diseases including schizophrenia. Investigation of C3 polymorphisms, circulating C3, cleavage product ASP/C3adesArg, and lipid metabolism. Cross-sectional analysis. C3 genotyping (CC vs GG for R102L) was performed on 434 Tunisian people consisting of 272 schizophrenic (SZ) patients and 162 control subjects. In a age- and gender-matched subgroups of the three genotypes (131 SZ and 112 NOR), plasma triglycerides, total cholesterol (C), LDL-C, HDL-C, ASP, and complement C3 were measured. C3 gene polymorphism influences BMI and plasma C3, ASP, triglyceride, total cholesterol, LDL-C and HDL-C among SZ patients (p < 0.05-0.0001), with increasing values demonstrated from CC (common form) to CG (heterozygote form) to GG (rare homozygote) forms. Significant correlations between plasma C3 and BMI, triglyceride, HDL-C and ASP (p < 0.05-0.0001) were observed, while ASP correlated with BMI and LDL-C (p = 0.005, p = 0.001, respectively) in SZ patients. Further, proportional conversion of C3 to ASP (%ASP/C3) also increased (p < 0.0001, GG>CG>CC). C3 polymorphisms and plasma C3, ASP and %ASP/C3 correlated with lipid parameters in this SZ population, suggesting that factors predisposing patients to schizophrenia are permissive for complement pathway activation and dyslipidemic influences. PMID:25720829

  20. Sundanese Complementation

    ERIC Educational Resources Information Center

    Kurniawan, Eri

    2013-01-01

    The focus of this thesis is the description and analysis of clausal complementation in Sundanese, an Austronesian language spoken in Indonesia. The thesis examined a range of clausal complement types in Sundanese, which consists of (i) "yen/(wi)rehna" "that" complements, (ii) "pikeun" "for" complements,…

  1. The Interaction of Classical Complement Component C1 with Parasite and Host Calreticulin Mediates Trypanosoma cruzi Infection of Human Placenta

    PubMed Central

    Castillo, Christian; Ramírez, Galia; Valck, Carolina; Aguilar, Lorena; Maldonado, Ismael; Rosas, Carlos; Galanti, Norbel; Kemmerling, Ulrike; Ferreira, Arturo

    2013-01-01

    Background 9 million people are infected with Trypanosoma cruzi in Latin America, plus more than 300,000 in the United States, Canada, Europe, Australia, and Japan. Approximately 30% of infected individuals develop circulatory or digestive pathology. While in underdeveloped countries transmission is mainly through hematophagous arthropods, transplacental infection prevails in developed ones. Methodology/Principal Findings During infection, T. cruzi calreticulin (TcCRT) translocates from the endoplasmic reticulum to the area of flagellum emergence. There, TcCRT acts as virulence factor since it binds maternal classical complement component C1q that recognizes human calreticulin (HuCRT) in placenta, with increased parasite infectivity. As measured ex vivo by quantitative PCR in human placenta chorionic villi explants (HPCVE) (the closest available correlate of human congenital T. cruzi infection), C1q mediated up to a 3–5-fold increase in parasite load. Because anti-TcCRT and anti-HuCRT F(ab′)2 antibody fragments are devoid of their Fc-dependent capacity to recruit C1q, they reverted the C1q-mediated increase in parasite load by respectively preventing its interaction with cell-bound CRTs from both parasite and HPCVE origins. The use of competing fluid-phase recombinant HuCRT and F(ab′)2 antibody fragments anti-TcCRT corroborated this. These results are consistent with a high expression of fetal CRT on placental free chorionic villi. Increased C1q-mediated infection is paralleled by placental tissue damage, as evidenced by histopathology, a damage that is ameliorated by anti-TcCRT F(ab′)2 antibody fragments or fluid-phase HuCRT. Conclusions/Significance T. cruzi infection of HPCVE is importantly mediated by human and parasite CRTs and C1q. Most likely, C1q bridges CRT on the parasite surface with its receptor orthologue on human placental cells, thus facilitating the first encounter between the parasite and the fetal derived placental tissue. The results

  2. Recent Developments in Low Molecular Weight Complement Inhibitors

    PubMed Central

    Qu, Hongchang; Ricklin, Daniel; Lambris, John D.

    2009-01-01

    As a key part of the innate immune system, complement plays an important role not only in defending invading pathogens but also in many other biological processes. Inappropriate or excessive activation of complement has been linked to many autoimmune, inflammatory, and neurodegenerative diseases, as well as ischemia-reperfusion injury and cancer. A wide array of low molecular weight complement inhibitors has been developed to target various components of the complement cascade. Their efficacy has been demonstrated in numerous in vitro and in vivo experiments. Though none of these inhibitors has reached the market so far, some of them have entered clinical trials and displayed promising results. This review provides a brief overview of the currently developed low molecular weight complement inhibitors, including short peptides and synthetic small molecules, with an emphasis on those targeting components C1 and C3, and the anaphylatoxin receptors. PMID:19800693

  3. Degradation of C3 by Streptococcus pneumoniae.

    PubMed

    Angel, C S; Ruzek, M; Hostetter, M K

    1994-09-01

    After growth to exponential phase in Todd-Hewitt broth, clinical and laboratory isolates of Streptococcus pneumoniae serotypes 3, 4, and 14 readily degraded first the beta and then the alpha chains of purified human C3 in the absence of serum or other complement proteins, as assessed by SDS-PAGE. With exponentially growing pneumococci, degradation of native C3 was detectable within 30 min; methylamine-treated C3 and preformed C3b were degraded with equal avidity. Pneumococcal C3-degrading activity was cell associated, abolished by heat killing, and independent of the presence of the polysaccharide capsule. After degradation, 44% of C3 molecules contained a disrupted thiolester bond. Pneumococci treated with 100 micrograms of mutanolysin released 94% of C3-degrading activity from the pneumococcal surface into the supernatant. These studies demonstrate that clinical and laboratory isolates of virulent pneumococci degrade and inactivate soluble C3. PMID:8077717

  4. Complement-mediated opsonization of invasive group A Streptococcus pyogenes strain AP53 is regulated by the bacterial two-component cluster of virulence responder/sensor (CovRS) system.

    PubMed

    Agrahari, Garima; Liang, Zhong; Mayfield, Jeffrey A; Balsara, Rashna D; Ploplis, Victoria A; Castellino, Francis J

    2013-09-20

    Group A Streptococcus pyogenes (GAS) strain AP53 is a primary isolate from a patient with necrotizing fasciitis. These AP53 cells contain an inactivating mutation in the sensor component of the cluster of virulence (cov) responder (R)/sensor (S) two-component gene regulatory system (covRS), which enhances the virulence of the primary strain, AP53/covR(+)S(-). However, specific mechanisms by which the covRS system regulates the survival of GAS in humans are incomplete. Here, we show a key role for covRS in the regulation of opsonophagocytosis of AP53 by human neutrophils. AP53/covR(+)S(-) cells displayed potent binding of host complement inhibitors of C3 convertase, viz. Factor H (FH) and C4-binding protein (C4BP), which concomitantly led to minimal C3b deposition on AP53 cells, further showing that these plasma protein inhibitors are active on GAS cells. This resulted in weak killing of the bacteria by human neutrophils and a corresponding high death rate of mice after injection of these cells. After targeted allelic alteration of covS(-) to wild-type covS (covS(+)), a dramatic loss of FH and C4BP binding to the AP53/covR(+)S(+) cells was observed. This resulted in elevated C3b deposition on AP53/covR(+)S(+) cells, a high level of opsonophagocytosis by human neutrophils, and a very low death rate of mice infected with AP53/covR(+)S(+). We show that covRS is a critical transcriptional regulator of genes directing AP53 killing by neutrophils and regulates the levels of the receptors for FH and C4BP, which we identify as the products of the fba and enn genes, respectively. PMID:23928307

  5. Complement-mediated Opsonization of Invasive Group A Streptococcus pyogenes Strain AP53 Is Regulated by the Bacterial Two-component Cluster of Virulence Responder/Sensor (CovRS) System*

    PubMed Central

    Agrahari, Garima; Liang, Zhong; Mayfield, Jeffrey A.; Balsara, Rashna D.; Ploplis, Victoria A.; Castellino, Francis J.

    2013-01-01

    Group A Streptococcus pyogenes (GAS) strain AP53 is a primary isolate from a patient with necrotizing fasciitis. These AP53 cells contain an inactivating mutation in the sensor component of the cluster of virulence (cov) responder (R)/sensor (S) two-component gene regulatory system (covRS), which enhances the virulence of the primary strain, AP53/covR+S−. However, specific mechanisms by which the covRS system regulates the survival of GAS in humans are incomplete. Here, we show a key role for covRS in the regulation of opsonophagocytosis of AP53 by human neutrophils. AP53/covR+S− cells displayed potent binding of host complement inhibitors of C3 convertase, viz. Factor H (FH) and C4-binding protein (C4BP), which concomitantly led to minimal C3b deposition on AP53 cells, further showing that these plasma protein inhibitors are active on GAS cells. This resulted in weak killing of the bacteria by human neutrophils and a corresponding high death rate of mice after injection of these cells. After targeted allelic alteration of covS− to wild-type covS (covS+), a dramatic loss of FH and C4BP binding to the AP53/covR+S+ cells was observed. This resulted in elevated C3b deposition on AP53/covR+S+ cells, a high level of opsonophagocytosis by human neutrophils, and a very low death rate of mice infected with AP53/covR+S+. We show that covRS is a critical transcriptional regulator of genes directing AP53 killing by neutrophils and regulates the levels of the receptors for FH and C4BP, which we identify as the products of the fba and enn genes, respectively. PMID:23928307

  6. Immunogenetic evidence for the phylogenetic sister group relationship of dogs and bears (Mammalia, Carnivora: Canidae and Crsidae). a comparative determinant analysis of carnivoran albumin, c3 complement and immunoglobulin micro-chain.

    PubMed

    Schreiber, A; Eulenberger, K; Bauer, K

    1998-01-01

    Thirty-seven antigenic determinants were identified in the albumins, the immunoglobulin micro- and IgG(Fc) chains, and the C3 proteins of 51 carnivoran (sub)species from 31 genera, and in 12 noncarnivoran mammals. In addition to 19 determinants plesiomorphic for Carnivora as an order, 18 synapomorphic epitopes of carnivoran families revealed nine phylogenetic reaction groups: (1) canids, (2) ursids, (3) the racoon, (4) the Weddell seal, (5) the lesser panda, (6) the harbour seal, (7) mustelids, (8) viverrids and hyaenas, and (9) felids. These data identify Canoidea (Canidae, Ursidae, Phocidae, Procyonidae, Ailuridae, Mustelidae) and Feloidea (Viverridae, Hyaenidae, Felidae) as two fundamentally differentiated lineages of Carnivora, and confirm the inclusion of seals among the former. The Ursidae are the sister group of the Canidae. The antigenic determinants in the studied proteins do not subdivide the Canidae, Ursidae and Felidae into immunologically differentiated lineages. PMID:9813413

  7. Expression of complement 3 and complement 5 in newt limb and lens regeneration.

    PubMed

    Kimura, Yuko; Madhavan, Mayur; Call, Mindy K; Santiago, William; Tsonis, Panagiotis A; Lambris, John D; Del Rio-Tsonis, Katia

    2003-03-01

    Some urodele amphibians possess the capacity to regenerate their body parts, including the limbs and the lens of the eye. The molecular pathway(s) involved in urodele regeneration are largely unknown. We have previously suggested that complement may participate in limb regeneration in axolotls. To further define its role in the regenerative process, we have examined the pattern of distribution and spatiotemporal expression of two key components, C3 and C5, during limb and lens regeneration in the newt Notophthalmus viridescens. First, we have cloned newt cDNAs encoding C3 and C5 and have generated Abs specifically recognizing these molecules. Using these newt-specific probes, we have found by in situ hybridization and immunohistochemical analysis that these molecules are expressed during both limb and lens regeneration, but not in the normal limb and lens. The C3 and C5 proteins were expressed in a complementary fashion during limb regeneration, with C3 being expressed mainly in the blastema and C5 exclusively in the wound epithelium. Similarly, during the process of lens regeneration, C3 was detected in the iris and cornea, while C5 was present in the regenerating lens vesicle as well as the cornea. The distinct expression profile of complement proteins in regenerative tissues of the urodele lens and limb supports a nonimmunologic function of complement in tissue regeneration and constitutes the first systematic effort to dissect its involvement in regenerative processes of lower vertebrate species. PMID:12594255

  8. Complement Evasion Mediated by Enhancement of Captured Factor H: Implications for Protection of Self-Surfaces from Complement

    PubMed Central

    Herbert, Andrew P.; Makou, Elisavet; Chen, Zhuo A.; Kerr, Heather; Richards, Anna; Rappsilber, Juri

    2015-01-01

    In an attempt to evade annihilation by the vertebrate complement system, many microbes capture factor H (FH), the key soluble complement-regulating protein in human plasma. However, FH is normally an active complement suppressor exclusively on self-surfaces and this selective action of FH is pivotal to self versus non-self discrimination by the complement system. We investigated whether the bacterially captured FH becomes functionally enhanced and, if so, how this is achieved at a structural level. We found, using site-directed and truncation mutagenesis, surface plasmon resonance, nuclear magnetic resonance spectroscopy, and cross-linking and mass spectrometry, that the N-terminal domain of Streptococcus pneumoniae protein PspC (PspCN) not only binds FH extraordinarily tightly but also holds it in a previously uncharacterized conformation. Functional enhancement arises from exposure of a C-terminal cryptic second binding site in FH for C3b, the activation-specific fragment of the pivotal complement component, C3. This conformational change of FH doubles its affinity for C3b and increases 5-fold its ability to accelerate decay of the binary enzyme (C3bBb) responsible for converting C3 to C3b in an amplification loop. Despite not sharing critical FH-binding residues, PspCNs from D39 and Tigr4 S. pneumoniae exhibit similar FH-anchoring and enhancing properties. We propose that these bacterial proteins mimic molecular markers of self-surfaces, providing a compelling hypothesis for how FH prevents complement-mediated injury to host tissue while lacking efficacy on virtually all other surfaces. In hemolysis assays with 2-aminoethylisothiouronium bromide–treated erythrocytes that recapitulate paroxysmal nocturnal hemoglobinuria, PspCN enhanced protection of cells by FH, suggesting a new paradigm for therapeutic complement suppression. PMID:26459349

  9. Complement Evasion Mediated by Enhancement of Captured Factor H: Implications for Protection of Self-Surfaces from Complement.

    PubMed

    Herbert, Andrew P; Makou, Elisavet; Chen, Zhuo A; Kerr, Heather; Richards, Anna; Rappsilber, Juri; Barlow, Paul N

    2015-11-15

    In an attempt to evade annihilation by the vertebrate complement system, many microbes capture factor H (FH), the key soluble complement-regulating protein in human plasma. However, FH is normally an active complement suppressor exclusively on self-surfaces and this selective action of FH is pivotal to self versus non-self discrimination by the complement system. We investigated whether the bacterially captured FH becomes functionally enhanced and, if so, how this is achieved at a structural level. We found, using site-directed and truncation mutagenesis, surface plasmon resonance, nuclear magnetic resonance spectroscopy, and cross-linking and mass spectrometry, that the N-terminal domain of Streptococcus pneumoniae protein PspC (PspCN) not only binds FH extraordinarily tightly but also holds it in a previously uncharacterized conformation. Functional enhancement arises from exposure of a C-terminal cryptic second binding site in FH for C3b, the activation-specific fragment of the pivotal complement component, C3. This conformational change of FH doubles its affinity for C3b and increases 5-fold its ability to accelerate decay of the binary enzyme (C3bBb) responsible for converting C3 to C3b in an amplification loop. Despite not sharing critical FH-binding residues, PspCNs from D39 and Tigr4 S. pneumoniae exhibit similar FH-anchoring and enhancing properties. We propose that these bacterial proteins mimic molecular markers of self-surfaces, providing a compelling hypothesis for how FH prevents complement-mediated injury to host tissue while lacking efficacy on virtually all other surfaces. In hemolysis assays with 2-aminoethylisothiouronium bromide-treated erythrocytes that recapitulate paroxysmal nocturnal hemoglobinuria, PspCN enhanced protection of cells by FH, suggesting a new paradigm for therapeutic complement suppression. PMID:26459349

  10. Studies on human blood lymphocytes with iC3b (type 3) complement receptors. II. Characterization of subsets which regulate pokeweed mitogen-induced lymphocyte proliferation and immunoglobulin synthesis.

    PubMed Central

    Abo, W; Gray, J D; Bakke, A C; Horwitz, D A

    1987-01-01

    Human blood lymphocytes that express Type 3 complement receptors (CR3) can be divided into a major subset with high density Fc receptors for IgG (FcR) identified with the monoclonal antibody Leu 11 and two minor subsets which display either CD8 (Leu 2) or CD4 (Leu 3) markers. We isolated CR3+ lymphocyte subsets and examined them for regulatory effects on pokeweed mitogen (PWM) stimulated cells. The FCR CR3+ cell suppressed PWM-induced proliferation and Ig production. Pretreatment of these lymphocytes with immune complexes was required to suppress proliferation, but not IgG production. The CR3+ Leu 2+ FCR- subset also had suppressive activity, but this effect was not observed unless the CR3+ Leu 3+ enriched subset was removed. In fact, the CR3+ Leu 3+ enriched subset enhanced IgG synthesis. Brief exposure of CR3+ lymphocytes to recombinant interleukin 2, recombinant alpha-interferon, but not gamma-interferon, markedly enhanced the inhibitory effect. Time course studies and a comparison of inhibition of Ig synthesis with natural killer cell activity suggested that CR3+ lymphocytes act shortly after lymphocytes are exposed to PWM and that Ig production was regulated by suppression rather than cytotoxicity. These CR3+ lymphocyte subsets may have broad antigen non-specific effects on immunoglobulin synthesis. PMID:2955973

  11. C3 nephritic factor and hypocomplementaemia in a clinically healthy individual.

    PubMed Central

    Gewurz, A T; Imherr, S M; Strauss, S; Gewurz, H; Mold, C

    1983-01-01

    Nephritic factor was detected in an individual whose serum showed a selective decrease in the third component of complement (C3) during and subsequent to an illness resembling disseminated gonococcal infection (DGI). As is characteristic of C3 nephritic factor (C3NeF), its activity was heat stable, was associated with IgG, and enhanced cleavage of normal human serum C3 via the alternative pathway. However, unlike previously reported cases of C3NeF detection in association with glomerulonephritis and/or lipodystrophy, this patient has had no significant disease before or more than 2 years after the apparent DGI. The significance of C3NeF in a healthy individual is unexplained, but this study suggests its occurrence may be more ubiquitous than previously suspected. PMID:6616970

  12. Experimental design of complement component 5a-induced acute lung injury (C5a-ALI): a role of CC-chemokine receptor type 5 during immune activation by anaphylatoxin

    PubMed Central

    Russkamp, Norman F.; Ruemmler, Robert; Roewe, Julian; Moore, Bethany B.; Ward, Peter A.; Bosmann, Markus

    2015-01-01

    Excessive activation of the complement system is detrimental in acute inflammatory disorders. In this study, we analyzed the role of complement-derived anaphylatoxins in the pathogenesis of experimental acute lung injury/acute respiratory distress syndrome (ALI/ARDS) in C57BL/6J mice. Intratracheal administration of recombinant mouse complement component (C5a) caused alveolar inflammation with abundant recruitment of Ly6-G+CD11b+ leukocytes to the alveolar spaces and severe alveolar-capillary barrier dysfunction (C5a-ALI; EC50[C5a] = 20 ng/g body weight). Equimolar concentrations of C3a or desarginated C5a (C5adesArg) did not induce alveolar inflammation. The severity of C5a-ALI was aggravated in C5-deficient mice. Depletion of Ly6-G+ cells and use of C5aR1−/− bone marrow chimeras suggested an essential role of C5aR1+ hematopoietic cells in C5a-ALI. Blockade of PI3K/Akt and MEK1/2 kinase pathways completely abrogated lung injury. The mechanistic description is that C5a altered the alveolar cytokine milieu and caused significant release of CC-chemokines. Mice with genetic deficiency of CC-chemokine receptor (CCR) type 5, the common receptor of chemokine (C-C motif) ligand (CCL) 3, CCL4, and CCL5, displayed reduced lung damage. Moreover, treatment with a CCR5 antagonist, maraviroc, was protective against C5a-ALI. In summary, our results suggest that the detrimental effects of C5a in this model are partly mediated through CCR5 activation downstream of C5aR1, which may be evaluated for potential therapeutic exploitation in ALI/ARDS.—Russkamp, N. F., Ruemmler, R., Roewe, J., Moore, B. B., Ward, P. A., Bosmann, M. Experimental design of complement component 5a-induced acute lung injury (C5a-ALI): a role of CC-chemokine receptor type 5 during immune activation by anaphylatoxin. PMID:25999468

  13. Target deletion of complement component 9 attenuates antibody-mediated hemolysis and lipopolysaccharide (LPS)-induced acute shock in mice

    PubMed Central

    Fu, Xiaoyan; Ju, Jiyu; Lin, Zhijuan; Xiao, Weiling; Li, Xiaofang; Zhuang, Baoxiang; Zhang, Tingting; Ma, Xiaojun; Li, Xiangyu; Ma, Chao; Su, Weiliang; Wang, Yuqi; Qin, Xuebin; Liang, Shujuan

    2016-01-01

    Terminal complement membrane attack complex (MAC) formation is induced initially by C5b, followed by the sequential condensation of the C6, C7, C8. Polymerization of C9 to the C5b-8 complex forms the C5b-9 (or MAC). The C5b-9 forms lytic or non lytic pores in the cell membrane destroys membrane integrity. The biological functionalities of MAC has been previously investigated by using either the mice deficient in C5 and C6, or MAC’s regulator CD59. However, there is no available C9 deficient mice (mC9−/−) for directly dissecting the role of C5b-9 in the pathogenesis of human diseases. Further, since C5b-7 and C5b-8 complexes form non lytic pore, it may also plays biological functionality. To better understand the role of terminal complement cascades, here we report a successful generation of mC9−/−. We demonstrated that lack of C9 attenuates anti-erythrocyte antibody-mediated hemolysis or LPS-induced acute shock. Further, the rescuing effect on the acute shock correlates with the less release of IL-1β in mC9−/−, which is associated with suppression of MAC-mediated inflammasome activation in mC9−/−. Taken together, these results not only confirm the critical role of C5b-9 in complement-mediated hemolysis and but also highlight the critical role of C5b-9 in inflammasome activation. PMID:27444648

  14. Target deletion of complement component 9 attenuates antibody-mediated hemolysis and lipopolysaccharide (LPS)-induced acute shock in mice.

    PubMed

    Fu, Xiaoyan; Ju, Jiyu; Lin, Zhijuan; Xiao, Weiling; Li, Xiaofang; Zhuang, Baoxiang; Zhang, Tingting; Ma, Xiaojun; Li, Xiangyu; Ma, Chao; Su, Weiliang; Wang, Yuqi; Qin, Xuebin; Liang, Shujuan

    2016-01-01

    Terminal complement membrane attack complex (MAC) formation is induced initially by C5b, followed by the sequential condensation of the C6, C7, C8. Polymerization of C9 to the C5b-8 complex forms the C5b-9 (or MAC). The C5b-9 forms lytic or non lytic pores in the cell membrane destroys membrane integrity. The biological functionalities of MAC has been previously investigated by using either the mice deficient in C5 and C6, or MAC's regulator CD59. However, there is no available C9 deficient mice (mC9(-/-)) for directly dissecting the role of C5b-9 in the pathogenesis of human diseases. Further, since C5b-7 and C5b-8 complexes form non lytic pore, it may also plays biological functionality. To better understand the role of terminal complement cascades, here we report a successful generation of mC9(-/-). We demonstrated that lack of C9 attenuates anti-erythrocyte antibody-mediated hemolysis or LPS-induced acute shock. Further, the rescuing effect on the acute shock correlates with the less release of IL-1β in mC9(-/-), which is associated with suppression of MAC-mediated inflammasome activation in mC9(-/-). Taken together, these results not only confirm the critical role of C5b-9 in complement-mediated hemolysis and but also highlight the critical role of C5b-9 in inflammasome activation. PMID:27444648

  15. Eculizumab and Recurrent C3 Glomerulonephritis

    PubMed Central

    Gurkan, Sevgi; Fyfe, Billie; Weiss, Lynne; Xiao, Xue; Zhang, Yuzhou; Smith, Richard J.

    2015-01-01

    Background and objectives Hyperactivity of the alternative complement pathway is the principle defect in the C3 glomerulopathies (C3G). Eculizumab, a monoclonal antibody that binds to C5 to prevent formation of the membrane attack complex, has been shown to be beneficial in some patients with this disease. Design, setting, participants & measurements In this open-label, proof-of-concept efficacy-and-safety study, a patient with the initial diagnosis of Dense Deposit Disease (DDD) and allograft recurrence of C3 (C3GN) glomerulonephritis was treated with eculizumab every-other-week for 1 year. The patient had pathological evidence of C3GN and proteinuria >1 g/d at enrollment. He underwent graft biopsy before enrollment and repeat biopsy at 6 months and 12 months. Results Although no mutations were identified in complement genes, functional studies were positive for C3 nephritic factors and elevated levels of soluble membrane attack complex (sMAC). On therapy, sMAC levels normalized and although proteinuria initially decreased, during therapy it increased reaching pre-treatment levels at 12 months. Although serum creatinine remained stable, repeat allograft biopsies showed progression of disease. Conclusions Clinical and histopathologic data suggest a partial response to eculizumab in this patient. While eculizumab blocked activation of the terminal complement cascade, persistent dysregulation of alternative pathway remained, showing that eculizumab alone cannot control disease in this patient. Additional research is required to identify effective anticomplement therapy for this group of C3G patients. PMID:23689905

  16. Phylogenetic aspects of the complement system.

    PubMed

    Zarkadis, I K; Mastellos, D; Lambris, J D

    2001-01-01

    During evolution two general systems of immunity have emerged: innate or, natural immunity and adaptive (acquired), or specific immunity. The innate system is phylogenetically older and is found in some form in all multicellular organisms, whereas the adaptive system appeared about 450 million years ago and is found in all vertebrates except jawless fish. The complement system in higher vertebrates plays an important role as an effector of both the innate and the acquired immune response, and also participates in various immunoregulatory processes. In lower vertebrates complement is activated by the alternative and lectin pathways and is primarily involved in the opsonization of foreign material. The Agnatha (the most primitive vertebrate species) possess the alternative and lectin pathways while cartilaginous fish are the first species in which the classical pathway appears following the emergence of immunoglobulins. The rest of the poikilothermic species, ranging from teleosts to reptilians, appear to contain a well-developed complement system resembling that of the homeothermic vertebrates. It seems that most of the complement components have appeared after the duplication of primordial genes encoding C3/C4/C5, fB/C2, C1s/C1r/MASP-1/MASP-2, and C6/C7/C8/C9 molecules, in a process that led to the formation of distinct activation pathways. However, unlike homeotherms, several species of poikilotherms (e.g. trout) have recently been shown to possess multiple forms of complement components (C3, factor B) that are structurally and functionally more diverse than those of higher vertebrates. We hypothesize that this remarkable diversity has allowed these animals to expand their innate capacity for immune recognition and response. Recent studies have also indicated the possible presence of complement receptors in protochordates and lower vertebrates. In conclusion, there is considerable evidence suggesting that the complement system is present in the entire lineage of

  17. The alternative complement component factor B regulates UV-induced oedema, systemic suppression of contact and delayed hypersensitivity, and mast cell infiltration into the skin.

    PubMed

    Byrne, Scott N; Hammond, Kirsten J L; Chan, Carling Y-Y; Rogers, Linda J; Beaugie, Clare; Rana, Sabita; Marsh-Wakefield, Felix; Thurman, Joshua M; Halliday, Gary M

    2015-04-01

    Ultraviolet (UV) wavelengths in sunlight are the prime cause of skin cancer in humans with both the UVA and UVB wavebands making a contribution to photocarcinogenesis. UV has many different biological effects on the skin that contribute to carcinogenesis, including suppression of adaptive immunity, sunburn and altering the migration of mast cells into and away from irradiated skin. Many molecular mechanisms have been identified as contributing to skin responses to UV. Recently, using gene set enrichment analysis of microarray data, we identified the alternative complement pathway with a central role for factor B (fB) in UVA-induced immunosuppression. In the current study we used mice genetically deficient in fB (fB-/- mice) to study the functional role of the alternative complement pathway in skin responses to UV. We found that fB is required for not only UVA but also UVB-induced immunosuppression and solar-simulated UV induction of the oedemal component of sunburn. Factor B-/- mice had a larger number of resident skin mast cells than control mice, but unlike the controls did not respond to UV by increasing mast cell infiltration into the skin. This study provides evidence for a function role for fB in skin responses to UV radiation. Factor B regulates UVA and UVB induced immunosuppression, UV induced oedema and mast cell infiltration into the skin. The alternative complement pathway is therefore an important regulator of skin responses to UV. PMID:25645888

  18. On the Functional Overlap between Complement and Anti-Microbial Peptides

    PubMed Central

    Zimmer, Jana; Hobkirk, James; Mohamed, Fatima; Browning, Michael J.; Stover, Cordula M.

    2015-01-01

    Intriguingly, activated complement and anti-microbial peptides share certain functionalities; lytic, phagocytic, and chemo-attractant activities and each may, in addition, exert cell instructive roles. Each has been shown to have distinct LPS detoxifying activity and may play a role in the development of endotoxin tolerance. In search of the origin of complement, a functional homolog of complement C3 involved in opsonization has been identified in horseshoe crabs. Horseshoe crabs possess anti-microbial peptides able to bind to acyl chains or phosphate groups/saccharides of endotoxin, LPS. Complement activity as a whole is detectable in marine invertebrates. These are also a source of anti-microbial peptides with potential pharmaceutical applicability. Investigating the locality for the production of complement pathway proteins and their role in modulating cellular immune responses are emerging fields. The significance of local synthesis of complement components is becoming clearer from in vivo studies of parenchymatous disease involving specifically generated, complement-deficient mouse lines. Complement C3 is a central component of complement activation. Its provision by cells of the myeloid lineage varies. Their effector functions in turn are increased in the presence of anti-microbial peptides. This may point to a potentiating range of activities, which should serve the maintenance of health but may also cause disease. Because of the therapeutic implications, this review will consider closely studies dealing with complement activation and anti-microbial peptide activity in acute inflammation (e.g., dialysis-related peritonitis, appendicitis, and ischemia). PMID:25646095

  19. On the Functional Overlap between Complement and Anti-Microbial Peptides.

    PubMed

    Zimmer, Jana; Hobkirk, James; Mohamed, Fatima; Browning, Michael J; Stover, Cordula M

    2014-01-01

    Intriguingly, activated complement and anti-microbial peptides share certain functionalities; lytic, phagocytic, and chemo-attractant activities and each may, in addition, exert cell instructive roles. Each has been shown to have distinct LPS detoxifying activity and may play a role in the development of endotoxin tolerance. In search of the origin of complement, a functional homolog of complement C3 involved in opsonization has been identified in horseshoe crabs. Horseshoe crabs possess anti-microbial peptides able to bind to acyl chains or phosphate groups/saccharides of endotoxin, LPS. Complement activity as a whole is detectable in marine invertebrates. These are also a source of anti-microbial peptides with potential pharmaceutical applicability. Investigating the locality for the production of complement pathway proteins and their role in modulating cellular immune responses are emerging fields. The significance of local synthesis of complement components is becoming clearer from in vivo studies of parenchymatous disease involving specifically generated, complement-deficient mouse lines. Complement C3 is a central component of complement activation. Its provision by cells of the myeloid lineage varies. Their effector functions in turn are increased in the presence of anti-microbial peptides. This may point to a potentiating range of activities, which should serve the maintenance of health but may also cause disease. Because of the therapeutic implications, this review will consider closely studies dealing with complement activation and anti-microbial peptide activity in acute inflammation (e.g., dialysis-related peritonitis, appendicitis, and ischemia). PMID:25646095

  20. [Atypical HUS caused by complement-related abnormalities].

    PubMed

    Yoshida, Yoko; Matsumoto, Masanori

    2015-02-01

    Atypical hemolytic uremic syndrome (aHUS) is a rare disease characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. The term aHUS was historically used to distinguish this disorder from Shiga-toxin producing Escherichia coli (STEC)-HUS. Many aHUS cases (approximately 70%) are reportedly caused by uncontrolled complement activation due to genetic mutations in the alternative pathway, including complement factor H (CFH), complement factor I (CFI), membrane cofactor protein (MCP), thrombomodulin (THBD), complement component C3 (C3), and complement factor B (CFB). Mutations in the coagulation pathway, such as diacylglycerol kinase ε (DGKE) and plasminogen, are also reported to be causes of aHUS. In this review, we have focused on aHUS due to complement dysfunction. aHUS is suspected based on plasma ADAMTS13 activity of 10% or more, and being negative for STEC-HUS, in addition to the aforementioned triad. Complement genetic studies provide a more specific diagnosis of aHUS. Plasma therapy is the first-line treatment for patients with aHUS and should be initiated as soon as the diagnosis is suspected. Recently, eculizumab, a humanized monoclonal antibody against C5, was shown to be an effective treatment for aHUS. Therefore, early diagnosis and identification of the underlying pathogenic mechanism is important for improving the outcome of aHUS. PMID:25765799

  1. Complement component C5a Promotes Expression of IL-22 and IL-17 from Human T cells and its Implication in Age-related Macular Degeneration

    PubMed Central

    2011-01-01

    Background Age related macular degeneration (AMD) is the leading cause of irreversible blindness in elderly populations worldwide. Inflammation, among many factors, has been suggested to play an important role in AMD pathogenesis. Recent studies have demonstrated a strong genetic association between AMD and complement factor H (CFH), the down-regulatory factor of complement activation. Elevated levels of complement activating molecules including complement component 5a (C5a) have been found in the serum of AMD patients. Our aim is to study whether C5a can impact human T cells and its implication in AMD. Methods Human peripheral blood mononuclear cells (PBMCs) were isolated from the blood of exudative form of AMD patients using a Ficoll gradient centrifugation protocol. Intracellular staining and enzyme-linked immunosorbent assays were used to measure protein expression. Apoptotic cells were detected by staining of cells with the annexin-V and TUNEL technology and analyzed by a FACS Caliber flow cytometer. SNP genotyping was analyzed by TaqMan genotyping assay using the Real-time PCR system 7500. Results We show that C5a promotes interleukin (IL)-22 and IL-17 expression by human CD4+ T cells. This effect is dependent on B7, IL-1β and IL-6 expression from monocytes. We have also found that C5a could protect human CD4+ cells from undergoing apoptosis. Importantly, consistent with a role of C5a in promoting IL-22 and IL-17 expression, significant elevation in IL-22 and IL-17 levels was found in AMD patients as compared to non-AMD controls. Conclusions Our results support the notion that C5a may be one of the factors contributing to the elevated serum IL-22 and IL-17 levels in AMD patients. The possible involvement of IL-22 and IL-17 in the inflammation that contributes to AMD may herald a new approach to treat AMD. PMID:21762495

  2. Absence of interaction of genomic components and complementation between Mungbean yellow mosaic India virus isolates in cowpea.

    PubMed

    Surendranath, B; Usharani, K S; Nagma, A; Victoria, A K; Malathi, V G

    2005-09-01

    Agroinoculations were performed with DNA A and DNA B components of Mungbean yellow mosaic India virus (MYMIV) isolates differing in their infectivity on cowpea. Exchange of genomic components of the MYMIV isolates occurred in all the leguminous species but not in cowpea. Extremely low viral DNA accumulation and atypical leaf curl symptoms produced by reassortants in cowpea suggest barriers both for replication and systemic movement despite genetic similarity. PMID:15931466

  3. In vitro and in vivo changes in human complement caused by silage.

    PubMed Central

    Olenchock, S A; May, J J; Pratt, D S; Lewis, D M; Mull, J C; Stallones, L

    1986-01-01

    Aqueous extracts of silage samples from four farms in up-state New York were reacted in vitro with normal human serum. Hemolytic levels of complement component C3 were consumed in a dose-dependent fashion, and the four extracts differed in their relative activity rankings. Studies with chelated serum indicate that the alternative complement pathway is involved in the activation, and the active fragment C3b was demonstrated. Serum levels of hemolytic C3 and C4 in vivo were quantified before and after farmers performed their normal silo unloading operations. Although the study groups were small, suggestive evidence of in vivo complement consumption was found. IgE-related allergy did not appear to be of significance to the study groups. Complement activation may be an initiator of or contributor to adverse reactions in farmers who are exposed to airborne silage dusts. Images FIGURE 2. FIGURE 3. PMID:3709488

  4. Regulatory Components of the Alternative Complement Pathway in Endothelial Cell Cytoplasm, Factor H and Factor I, Are Not Packaged in Weibel-Palade Bodies

    PubMed Central

    Turner, Nancy A.; Sartain, Sarah E.; Hui, Shiu-Ki; Moake, Joel L.

    2015-01-01

    It was recently reported that factor H, a regulatory component of the alternative complement pathway, is stored with von Willebrand factor (VWF) in the Weibel-Palade bodies of endothelial cells. If this were to be the case, it would have therapeutic importance for patients with the atypical hemolytic-uremic syndrome that can be caused either by a heterozygous defect in the factor H gene or by the presence of an autoantibody against factor H. The in vivo Weibel-Palade body secretagogue, des-amino-D-arginine vasopressin (DDAVP), would be expected to increase transiently the circulating factor H levels, in addition to increasing the circulating levels of VWF. We describe experiments demonstrating that factor H is released from endothelial cell cytoplasm without a secondary storage site. These experiments showed that factor H is not stored with VWF in endothelial cell Weibel-Palade bodies, and is not secreted in response in vitro in response to the Weibel-Palade body secretagogue, histamine. Furthermore, the in vivo Weibel-Palade body secretagogue, DDAVP does not increase the circulating factor H levels concomitantly with DDAVP-induced increased VWF. Factor I, a regulatory component of the alternative complement pathway that is functionally related to factor H, is also located in endothelial cell cytoplasm, and is also not present in endothelial cell Weibel-Palade bodies. Our data demonstrate that the factor H and factor I regulatory proteins of the alternative complement pathway are not stored in Weibel-Palade bodies. DDAVP induces the secretion into human plasma of VWF —- but not factor H. PMID:25803806

  5. Solution Structures of Complement C2 and Its C4 Complexes Propose Pathway-specific Mechanisms for Control and Activation of the Complement Proconvertases.

    PubMed

    Mortensen, Sofia; Jensen, Jan K; Andersen, Gregers R

    2016-08-01

    The lectin (LP) and classical (CP) pathways are two of the three main activation cascades of the complement system. These pathways start with recognition of different pathogen- or danger-associated molecular patterns and include identical steps of proteolytic activation of complement component C4, formation of the C3 proconvertase C4b2, followed by cleavage of complement component C2 within C4b2 resulting in the C3 convertase C4b2a. Here, we describe the solution structures of the two central complexes of the pathways, C3 proconvertase and C3 convertase, as well as the unbound zymogen C2 obtained by small angle x-ray scattering analysis. We analyzed both native and enzymatically deglycosylated C4b2 and C2 and showed that the resulting structural models were independent of the glycans. The small angle x-ray scattering-derived models suggest a different activation mode for the CP/LP C3 proconvertase as compared with that established for the alternative pathway proconvertase C3bB. This is likely due to the rather different structural and functional properties of the proteases activating the proconvertases. The solution structure of a stabilized form of the active CP/LP C3 convertase C4b2a is strikingly similar to the crystal structure of the alternative pathway C3 convertase C3bBb, which is in accordance with their identical functions in cleaving the complement proteins C3 and C5. PMID:27252379

  6. Complement activation by Coccidioides immitis: in vitro and clinical studies.

    PubMed Central

    Galgiani, J N; Yam, P; Petz, L D; Williams, P L; Stevens, D A

    1980-01-01

    Mycelial- or spherule-phase derivatives of Coccidioides immitis caused a decrease in vitro of total hemolytic complement in serum from a nonsensitized person. Activation involved both classic and alternative pathways as shown by deprssion of hemolytic C4 and by generation of products of activation of components C3, C4, and factor B. In addition, functional complement activity or immunoreactive levels of complement components or both were measured in 23 patients with self-limited or disseminated coccidioidomycosis. Low total hemolytic complement was found in nine, usually during the early phase of primary illness, and was transient. Hemolytic C4 was low, and the effect of inulin to decrease complement levels was blunted, suggested both classic and alternative pathways may be deficient. However, associated depression of immunoreactive levels of components assayed (C3, C4, C5, factor B, and properdin) was not consistently found. This disparity raises the possibility of enhanced in vitro inactivation analogous to activation by immune complexes. Images Fig. 2 PMID:6901703

  7. Interaction of toxic venoms with the complement system

    PubMed Central

    Birdsey, Vanessa; Lindorfer, Jean; Gewurz, H.

    1971-01-01

    Thirty-nine venoms from various vertebrate and invertebrate species were tested for their ability to consume haemolytic complement (C) activity upon incubation in fresh guinea-pig serum. Nineteen had `anti-complementary' activity, and these were provisionally sorted into the following groups: Pattern I—exemplified by the Naja haje (Egyptian cobra) and six other Elapidae species (all cobras), which induced selective consumption of C3—C9, and led to formation of a stable C3—C9-consuming intermediate; Pattern II—exemplified by the Agkistrodon rhodostoma (Malayan pit viper), Bitis arietans (puff adder), Bothrops jararaca (South American pit viper), Bothrops atrox (Fer de Lance) and three other species, which induced marked consumption of C4 and C2, as well as C3—C9, but did not form a stable C3—C9-consuming intermediate; and individual animals, e.g. the Lachesis muta (bushmaster), which induced other patterns (III—VI) of complement component consumption. Active fractions of representative venoms were partially purified by ion exchange and gel filtration chromatography and their interactions with the complement system characterized further. It is anticipated that these enzymes, with a capacity to activate the complement system in unique ways, will prove to be of further experimental usefulness. PMID:4398349

  8. Human L-ficolin, a Recognition Molecule of the Lectin Activation Pathway of Complement, Activates Complement by Binding to Pneumolysin, the Major Toxin of Streptococcus pneumoniae

    PubMed Central

    Ali, Youssif M.; Kenawy, Hany I.; Muhammad, Adnan; Sim, Robert B.

    2013-01-01

    The complement system is an essential component of the immune response, providing a critical line of defense against different pathogens including S. pneumoniae. Complement is activated via three distinct pathways: the classical (CP), the alternative (AP) and the lectin pathway (LP). The role of Pneumolysin (PLY), a bacterial toxin released by S. pneumoniae, in triggering complement activation has been studied in vitro. Our results demonstrate that in both human and mouse sera complement was activated via the CP, initiated by direct binding of even non-specific IgM and IgG3 to PLY. Absence of CP activity in C1q−/− mouse serum completely abolished any C3 deposition. However, C1q depleted human serum strongly opsonized PLY through abundant deposition of C3 activation products, indicating that the LP may have a vital role in activating the human complement system on PLY. We identified that human L-ficolin is the critical LP recognition molecule that drives LP activation on PLY, while all of the murine LP recognition components fail to bind and activate complement on PLY. This work elucidates the detailed interactions between PLY and complement and shows for the first time a specific role of the LP in PLY-mediated complement activation in human serum. PMID:24349316

  9. Early Cytokine Release in Response to Live Borrelia burgdorferi Sensu Lato Spirochetes Is Largely Complement Independent

    PubMed Central

    Säve, Susanne; Bergström, Sven; Forsberg, Pia; Jonsson, Nina; Ernerudh, Jan; Ekdahl, Kristina N.

    2014-01-01

    Aim Here we investigated the role of complement activation in phagocytosis and the release of cytokines and chemokines in response to two clinical isolates: Borrelia afzelii K78, which is resistant to complement-mediated lysis, and Borrelia garinii LU59, which is complement-sensitive. Methods Borrelia spirochetes were incubated in hirudin plasma, or hirudin-anticoagulated whole blood. Complement activation was measured as the generation of C3a and sC5b-9. Binding of the complement components C3, factor H, C4, and C4BP to the bacterial surfaces was analyzed. The importance of complement activation on phagocytosis, and on the release of cytokines and chemokines, was investigated using inhibitors acting at different levels of the complement cascade. Results 1) Borrelia garinii LU59 induced significantly higher complement activation than did Borrelia afzelii K78. 2) Borrelia afzelii K78 recruited higher amounts of factor H resulting in significantly lower C3 binding. 3) Both Borrelia strains were efficiently phagocytized by granulocytes and monocytes, with substantial inhibition by complement blockade at the levels of C3 and C5. 4) The release of the pro-inflammatory cytokines and chemokines IL-1β, IL-6, TNF, CCL20, and CXCL8, together with the anti-inflammatory IL-10, were increased the most (by>10-fold after exposure to Borrelia). 5) Both strains induced a similar release of cytokines and chemokines, which in contrast to the phagocytosis, was almost totally unaffected by complement blockade. Conclusions Our results show that complement activation plays an important role in the process of phagocytosis but not in the subsequent cytokine release in response to live Borrelia spirochetes. PMID:25265036

  10. Evolution of the complement system in protostomes revealed by de novo transcriptome analysis of six species of Arthropoda.

    PubMed

    Sekiguchi, Reo; Nonaka, Masaru

    2015-05-01

    To elucidate the evolutionary history of the complement system in Arthropoda, de novo transcriptome analysis was performed with six species among the Chelicerata, Myriapoda, and Crustacea, and complement genes were identified based on their characteristic domain structures. Complement C3 and factor B (FB) were identified from a sea spider, a jumping spider, and a centipede, but not from a sea firefly or two millipede species. No additional complement components identifiable by their characteristic domain structures were found from any of these six species. These results together with genome sequence information for several species of the Hexapoda suggest that the common ancestor of the Arthropoda possessed a simple complement system comprising C3 and FB, and thus resembled the alternative pathway of the mammalian complement system. It was lost at least twice independently during the evolution of Arthropoda in the millipede lineage and in the common ancestor of Crustacea and Hexapoda. PMID:25530095

  11. The Crystal Structure of Cobra Venom Factor, a Cofactor for C3- and C5-Convertase CVFBb

    SciTech Connect

    Krishnan, Vengadesan; Ponnuraj, Karthe; Xu, Yuanyuan; Macon, Kevin; Volanakis, John E.; Narayana, Sthanam V.L.

    2009-05-26

    Cobra venom factor (CVF) is a functional analog of human complement component C3b, the active fragment of C3. Similar to C3b, in human and mammalian serum, CVF binds factor B, which is then cleaved by factor D, giving rise to the CVFBb complex that targets the same scissile bond in C3 as the authentic complement convertases C4bC2a and C3bBb. Unlike the latter, CVFBb is a stable complex and an efficient C5 convertase. We solved the crystal structure of CVF, isolated from Naja naja kouthia venom, at 2.6 {angstrom} resolution. The CVF crystal structure, an intermediate between C3b and C3c, lacks the TED domain and has the CUB domain in an identical position to that seen in C3b. The similarly positioned CUB and slightly displaced C345c domains of CVF could play a vital role in the formation of C3 convertases by providing important primary binding sites for factor B.

  12. Collagen-binding Microbial Surface Components Recognizing Adhesive Matrix Molecule (MSCRAMM) of Gram-positive Bacteria Inhibit Complement Activation via the Classical Pathway*

    PubMed Central

    Kang, Mingsong; Ko, Ya-Ping; Liang, Xiaowen; Ross, Caná L.; Liu, Qing; Murray, Barbara E.; Höök, Magnus

    2013-01-01

    Members of a family of collagen-binding microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) from Gram-positive bacteria are established virulence factors in several infectious diseases models. Here, we report that these adhesins also can bind C1q and act as inhibitors of the classical complement pathway. Molecular analyses of Cna from Staphylococcus aureus suggested that this prototype MSCRAMM bound to the collagenous domain of C1q and interfered with the interactions of C1r with C1q. As a result, C1r2C1s2 was displaced from C1q, and the C1 complex was deactivated. This novel function of the Cna-like MSCRAMMs represents a potential immune evasion strategy that could be used by numerous Gram-positive pathogens. PMID:23720782

  13. C3 variants in Japanese.

    PubMed

    Nishimukai, H; Kitamura, H; Sano, Y; Tamaki, Y

    1985-01-01

    By high-voltage agarose gel electrophoresis, seven phenotypes of C3 were found in Japanese. The allele frequencies for C3*S, C3*S025, C3*S02, C3*F, C3*F06, C3*F065, and C3*F08 were 0.9943, 0.0003, 0.0003, 0.0006, 0.0003, 0.0021, and 0.0021, respectively. CH50, C3/C3c protein concentrations, and C3 hemolytic activities in fresh sera with variant C3 phenotypes were within the normal ranges. PMID:3988301

  14. The complement component C5 promotes liver steatosis and inflammation in murine non-alcoholic liver disease model.

    PubMed

    Bavia, Lorena; Cogliati, Bruno; Dettoni, Juliano Bertollo; Ferreira Alves, Venancio Avancini; Isaac, Lourdes

    2016-09-01

    Non-Alcoholic Fatty Liver Disease (NALD) is considering a hepatic manifestation of metabolic syndrome. Although the pathogenesis of NALD is not completely understood, insulin resistance and inflammatory cytokines are implicated. Considering that component C5 is a central mediator of inflammation, we investigated the role of C5 in the establishment of NALD. Eight to ten-week old B6 C5(+) and A/J C5(-) male mice were fed a high fat diet containing glucose (HFDG) for 6 and 10 weeks. We observed that B6 C5(+) mice HFDG-fed for 10 weeks developed hepatomegaly, triglycerides (TG) accumulation, steatosis and enhanced liver TNF-α, IL-6, IL-12p70 and IL-17 levels when compared to A/J C5(-) mice. Next, B6 C5(+) mice were compared with congenic B6 C5(-) mice. Again, B6 C5(+) HFDG-fed mice developed more steatosis, liver centro-lobular inflammation and presented higher levels of liver IL-1β, IL-12p70, IL-17 and TFG-β than B6 C5(-) mice under the same conditions. B6 C5(+) mice HFDG-fed also presented lower concentrations of serum albumin, serum cholesterol, blood leukocytes and liver NO production when compared with B6 C5(-) mice. We concluded that murine C5 contributes effectively to liver steatosis and inflammation in NALD pathogenesis. In addition, C5 is also important to control serum cholesterol and albumin levels in the C57BL/6 genetic background. PMID:27477770

  15. Antibodies That Efficiently Form Hexamers upon Antigen Binding Can Induce Complement-Dependent Cytotoxicity under Complement-Limiting Conditions.

    PubMed

    Cook, Erika M; Lindorfer, Margaret A; van der Horst, Hilma; Oostindie, Simone; Beurskens, Frank J; Schuurman, Janine; Zent, Clive S; Burack, Richard; Parren, Paul W H I; Taylor, Ronald P

    2016-09-01

    Recently, we demonstrated that IgG Abs can organize into ordered hexamers after binding their cognate Ags expressed on cell surfaces. This process is dependent on Fc:Fc interactions, which promote C1q binding, the first step in classical pathway complement activation. We went on to engineer point mutations that stimulated IgG hexamer formation and complement-dependent cytotoxicity (CDC). The hexamer formation-enhanced (HexaBody) CD20 and CD38 mAbs support faster, more robust CDC than their wild-type counterparts. To further investigate the CDC potential of these mAbs, we used flow cytometry, high-resolution digital imaging, and four-color confocal microscopy to examine their activity against B cell lines and primary chronic lymphocytic leukemia cells in sera depleted of single complement components. We also examined the CDC activity of alemtuzumab (anti-CD52) and mAb W6/32 (anti-HLA), which bind at high density to cells and promote substantial complement activation. Although we observed little CDC for mAb-opsonized cells reacted with sera depleted of early complement components, we were surprised to discover that the Hexabody mAbs, as well as ALM and W6/32, were all quite effective at promoting CDC in sera depleted of individual complement components C6 to C9. However, neutralization studies conducted with an anti-C9 mAb verified that C9 is required for CDC activity against cell lines. These highly effective complement-activating mAbs efficiently focus activated complement components on the cell, including C3b and C9, and promote CDC with a very low threshold of MAC binding, thus providing additional insight into their enhanced efficacy in promoting CDC. PMID:27474078

  16. Antibodies That Efficiently Form Hexamers upon Antigen Binding Can Induce Complement-Dependent Cytotoxicity under Complement-Limiting Conditions

    PubMed Central

    Cook, Erika M.; Lindorfer, Margaret A.; van der Horst, Hilma; Oostindie, Simone; Beurskens, Frank J.; Schuurman, Janine; Zent, Clive S.; Burack, Richard; Parren, Paul W. H. I.

    2016-01-01

    Recently, we demonstrated that IgG Abs can organize into ordered hexamers after binding their cognate Ags expressed on cell surfaces. This process is dependent on Fc:Fc interactions, which promote C1q binding, the first step in classical pathway complement activation. We went on to engineer point mutations that stimulated IgG hexamer formation and complement-dependent cytotoxicity (CDC). The hexamer formation–enhanced (HexaBody) CD20 and CD38 mAbs support faster, more robust CDC than their wild-type counterparts. To further investigate the CDC potential of these mAbs, we used flow cytometry, high-resolution digital imaging, and four-color confocal microscopy to examine their activity against B cell lines and primary chronic lymphocytic leukemia cells in sera depleted of single complement components. We also examined the CDC activity of alemtuzumab (anti-CD52) and mAb W6/32 (anti-HLA), which bind at high density to cells and promote substantial complement activation. Although we observed little CDC for mAb-opsonized cells reacted with sera depleted of early complement components, we were surprised to discover that the Hexabody mAbs, as well as ALM and W6/32, were all quite effective at promoting CDC in sera depleted of individual complement components C6 to C9. However, neutralization studies conducted with an anti-C9 mAb verified that C9 is required for CDC activity against cell lines. These highly effective complement-activating mAbs efficiently focus activated complement components on the cell, including C3b and C9, and promote CDC with a very low threshold of MAC binding, thus providing additional insight into their enhanced efficacy in promoting CDC. PMID:27474078

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

    PubMed

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

    2016-06-15

    Herpes simplex encephalitis (HSE) is characterized by a pronounced inflammatory activity in the central nervous system (CNS). Here, we investigated the acute and prolonged complement system activity in HSE patients, by using enzyme-linked immunosorbent assays (ELISAs) for numerous complement components (C). We found increased cerebrospinal fluid concentrations of C3a, C3b, C5 and C5a in HSE patients compared with healthy controls. C3a and C5a concentrations remained increased also compared with patient controls. Our results conclude that the complement system is activated in CNS during HSE in the acute phase, and interestingly also in later stages supporting previous reports of prolonged inflammation. PMID:27235358

  18. Complement-mediated 'bystander' damage initiates host NLRP3 inflammasome activation.

    PubMed

    Suresh, Rahul; Chandrasekaran, Prabha; Sutterwala, Fayyaz S; Mosser, David M

    2016-05-01

    Complement activation has long been associated with inflammation, primarily due to the elaboration of the complement anaphylotoxins C5a and C3a. In this work, we demonstrate that the phagocytosis of complement-opsonized particles promotes host inflammatory responses by a new mechanism that depends on the terminal complement components (C5b-C9). We demonstrate that during the phagocytosis of complement-opsonized particles, the membrane attack complex (MAC) of complement can be transferred from the activating particle to the macrophage plasma membrane by a 'bystander' mechanism. This MAC-mediated bystander damage initiates NLRP3 inflammasome activation, resulting in caspase-1 activation and IL-1β and IL-18 secretion. Inflammasome activation is not induced when macrophages phagocytize unopsonized particles or particles opsonized with serum deficient in one of the terminal complement components. The secretion of IL-1β and IL-18 by macrophages depends on NLRP3, ASC (also known as PYCARD) and caspase-1, as macrophages deficient in any one of these components fail to secrete these cytokines following phagocytosis. The phagocytosis of complement-opsonized particles increases leukocyte recruitment and promotes T helper 17 cell (TH17) biasing. These findings reveal a new mechanism by which complement promotes inflammation and regulates innate and adaptive immunity. PMID:27006116

  19. Complement involvement in kidney diseases: From physiopathology to therapeutical targeting

    PubMed Central

    Salvadori, Maurizio; Rosso, Giuseppina; Bertoni, Elisabetta

    2015-01-01

    Complement cascade is involved in several renal diseases and in renal transplantation. The different components of the complement cascade might represent an optimal target for innovative therapies. In the first section of the paper the authors review the physiopathology of complement involvement in renal diseases and transplantation. In some cases this led to a reclassification of renal diseases moving from a histopathological to a physiopathological classification. The principal issues afforded are: renal diseases with complement over activation, renal diseases with complement dysregulation, progression of renal diseases and renal transplantation. In the second section the authors discuss the several complement components that could represent a therapeutic target. Even if only the anti C5 monoclonal antibody is on the market, many targets as C1, C3, C5a and C5aR are the object of national or international trials. In addition, many molecules proved to be effective in vitro or in preclinical trials and are waiting to move to human trials in the future. PMID:25949931

  20. Complement Factor 3 Could Be an Independent Risk Factor for Mortality in Patients with HBV Related Acute-on-Chronic Liver Failure

    PubMed Central

    Zhang, Geng-lin; Zhang, Ting; Ye, Yi-nong; Liu, Jing; Zhang, Xiao-hong; Xie, Chan; Peng, Liang; Gao, Zhi-liang

    2016-01-01

    The complement is thought to be involved in the pathogenesis of multiple liver disorders. However, its role in patients with HBV related acute-on-chronic liver failure (HBV-ACLF) remains unclear. Serum levels of the third and fourth complement components (C3, C4) and complement function (CH50) were examined in this prospective, observational study. Associations between their expression and disease activity were analyzed. Survival was analyzed by Kaplan-Meier curves. Predictors of clinical outcome were determined by Cox regression analysis. C3, C4, and CH50 levels were significantly lower in HBV-ACLF patients compared to controls. C3, C4, and CH50 levels were negatively correlated with Tbil levels but positively associated with PTA levels. C3 levels were negatively associated with MELD-Na. C3 levels were significantly lower in HBV-ACLF patients who died compared to patients who survived. In a median hospital stay of 39 days, mortality occurred in 41 patients with a progressive increase based on C3 grade (P = 0.008). The actuarial probability of developing mortality was significantly higher in patients with low C3 grade compared to those with high C3 grade (P < 0.001). Multivariate Cox regression analysis showed that C3 levels were an independent predictor of mortality. Complement played a pathogenic role in HBV-ACLF patients and C3 was an independent predictor of mortality. PMID:27144164

  1. NETosing Neutrophils Activate Complement Both on Their Own NETs and Bacteria via Alternative and Non-alternative Pathways

    PubMed Central

    Yuen, Joshua; Pluthero, Fred G.; Douda, David N.; Riedl, Magdalena; Cherry, Ahmed; Ulanova, Marina; Kahr, Walter H. A.; Palaniyar, Nades; Licht, Christoph

    2016-01-01

    Neutrophils deposit antimicrobial proteins, such as myeloperoxidase and proteases on chromatin, which they release as neutrophil extracellular traps (NETs). Neutrophils also carry key components of the complement alternative pathway (AP) such as properdin or complement factor P (CFP), complement factor B (CFB), and C3. However, the contribution of these complement components and complement activation during NET formation in the presence and absence of bacteria is poorly understood. We studied complement activation on NETs and a Gram-negative opportunistic bacterial pathogen Pseudomonas aeruginosa (PA01, PAKwt, and PAKgfp). Here, we show that anaphylatoxin C5a, formyl-methionyl-leucyl-phenylalanine (fMLP) and phorbol myristate acetate (PMA), which activates NADPH oxidase, induce the release of CFP, CFB, and C3 from neutrophils. In response to PMA or P. aeruginosa, neutrophils secrete CFP, deposit it on NETs and bacteria, and induce the formation of terminal complement complexes (C5b–9). A blocking anti-CFP antibody inhibited AP-mediated but not non-AP-mediated complement activation on NETs and P. aeruginosa. Therefore, NET-mediated complement activation occurs via both AP- and non AP-based mechanisms, and AP-mediated complement activation during NETosis is dependent on CFP. These findings suggest that neutrophils could use their “AP tool kit” to readily activate complement on NETs and Gram-negative bacteria, such as P. aeruginosa, whereas additional components present in the serum help to fix non-AP-mediated complement both on NETs and bacteria. This unique mechanism may play important roles in host defense and help to explain specific roles of complement activation in NET-related diseases. PMID:27148258

  2. NETosing Neutrophils Activate Complement Both on Their Own NETs and Bacteria via Alternative and Non-alternative Pathways.

    PubMed

    Yuen, Joshua; Pluthero, Fred G; Douda, David N; Riedl, Magdalena; Cherry, Ahmed; Ulanova, Marina; Kahr, Walter H A; Palaniyar, Nades; Licht, Christoph

    2016-01-01

    Neutrophils deposit antimicrobial proteins, such as myeloperoxidase and proteases on chromatin, which they release as neutrophil extracellular traps (NETs). Neutrophils also carry key components of the complement alternative pathway (AP) such as properdin or complement factor P (CFP), complement factor B (CFB), and C3. However, the contribution of these complement components and complement activation during NET formation in the presence and absence of bacteria is poorly understood. We studied complement activation on NETs and a Gram-negative opportunistic bacterial pathogen Pseudomonas aeruginosa (PA01, PAKwt, and PAKgfp). Here, we show that anaphylatoxin C5a, formyl-methionyl-leucyl-phenylalanine (fMLP) and phorbol myristate acetate (PMA), which activates NADPH oxidase, induce the release of CFP, CFB, and C3 from neutrophils. In response to PMA or P. aeruginosa, neutrophils secrete CFP, deposit it on NETs and bacteria, and induce the formation of terminal complement complexes (C5b-9). A blocking anti-CFP antibody inhibited AP-mediated but not non-AP-mediated complement activation on NETs and P. aeruginosa. Therefore, NET-mediated complement activation occurs via both AP- and non AP-based mechanisms, and AP-mediated complement activation during NETosis is dependent on CFP. These findings suggest that neutrophils could use their "AP tool kit" to readily activate complement on NETs and Gram-negative bacteria, such as P. aeruginosa, whereas additional components present in the serum help to fix non-AP-mediated complement both on NETs and bacteria. This unique mechanism may play important roles in host defense and help to explain specific roles of complement activation in NET-related diseases. PMID:27148258

  3. Smoke Exposure Causes Endoplasmic Reticulum Stress and Lipid Accumulation in Retinal Pigment Epithelium through Oxidative Stress and Complement Activation*

    PubMed Central

    Kunchithapautham, Kannan; Atkinson, Carl; Rohrer, Bärbel

    2014-01-01

    Age-related macular degeneration (AMD) is a complex disease caused by genetic and environmental factors, including genetic variants in complement components and smoking. Smoke exposure leads to oxidative stress, complement activation, endoplasmic reticulum (ER) stress, and lipid dysregulation, which have all been proposed to be associated with AMD pathogenesis. Here we examine the effects of smoke exposure on the retinal pigment epithelium (RPE). Mice were exposed to cigarette smoke or filtered air for 6 months. RPE cells grown as stable monolayers were exposed to 5% cigarette smoke extract (CSE). Effects of smoke were determined by biochemical, molecular, and histological measures. Effects of the alternative pathway (AP) of complement and complement C3a anaphylatoxin receptor signaling were analyzed using knock-out mice or specific inhibitors. ER stress markers were elevated after smoke exposure in RPE of intact mice, which was eliminated in AP-deficient mice. To examine this relationship further, RPE monolayers were exposed to CSE. Short term smoke exposure resulted in production and release of complement C3, the generation of C3a, oxidative stress, complement activation on the cell membrane, and ER stress. Long term exposure to CSE resulted in lipid accumulation, and secretion. All measures were reversed by blocking C3a complement receptor (C3aR), alternative complement pathway signaling, and antioxidant therapy. Taken together, our results provide clear evidence that smoke exposure results in oxidative stress and complement activation via the AP, resulting in ER stress-mediated lipid accumulation, and further suggesting that oxidative stress and complement act synergistically in the pathogenesis of AMD. PMID:24711457

  4. Nonsynonymous single nucleotide polymorphisms in the complement component 3 gene are associated with risk of age-related macular degeneration: a meta-analysis.

    PubMed

    Qian-Qian, Yu; Yong, Yao; Jing, Zhu; Xin, Bao; Tian-Hua, Xie; Chao, Sun; Jia, Cao

    2015-05-01

    Nonsynonymous single nucleotide polymorphisms (SNPs) in complement component 3 (CC3) are associated with the risk of age-related macular degeneration (AMD), however, this association is not consistent among studies. To thoroughly address this issue, we performed an updated meta-analysis to evaluate the association between nine SNPs in the CC3 gene and AMD risk. A search was conducted of the PubMed database through 3rd Aug, 2014. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of associations. Based on the search criteria for manuscripts reporting AMD susceptibility related to CC3 in nine SNPs, 57 case-control studies from 22 different articles were retrieved. Significantly positive associations were found for the rs2230199 C/G SNP and AMD in the Caucasian population, as well as for the rs1047286 C/T SNP. Moreover, a relationship between the rs11569536 G/A SNP and AMD was detected. By contrast, a negative association was observed between rs2250656 A/G SNP and AMD risk. The present meta-analysis suggests that these four SNPs in the CC3 gene are potentially associated with the risk of AMD development. Further studies using larger sample sizes and accounting for gene-environment interactions should be conducted to elucidate the role of CC3 gene polymorphisms in AMD risk. PMID:25688879

  5. Complement Alternative Pathway Activation in Human Nonalcoholic Steatohepatitis

    PubMed Central

    Segers, Filip M.; Verdam, Froukje J.; de Jonge, Charlotte; Boonen, Bas; Driessen, Ann; Shiri-Sverdlov, Ronit; Bouvy, Nicole D.; Greve, Jan Willem M.; Buurman, Wim A.; Rensen, Sander S.

    2014-01-01

    The innate immune system plays a major role in the pathogenesis of nonalcoholic steatohepatitis (NASH). Recently we reported complement activation in human NASH. However, it remained unclear whether the alternative pathway of complement, which amplifies C3 activation and which is frequently associated with pathological complement activation leading to disease, was involved. Here, alternative pathway components were investigated in liver biopsies of obese subjects with healthy livers (n = 10) or with NASH (n = 12) using quantitative PCR, Western blotting, and immunofluorescence staining. Properdin accumulated in areas where neutrophils surrounded steatotic hepatocytes, and colocalized with the C3 activation product C3c. C3 activation status as expressed by the C3c/native C3 ratio was 2.6-fold higher (p<0.01) in subjects with NASH despite reduced native C3 concentrations (0.94±0.12 vs. 0.57±0.09; p<0.01). Hepatic properdin levels positively correlated with levels of C3c (rs = 0.69; p<0.05) and C3c/C3 activation ratio (rs = 0.59; p<0.05). C3c, C3 activation status (C3c/C3 ratio) and properdin levels increased with higher lobular inflammation scores as determined according to the Kleiner classification (C3c: p<0.01, C3c/C3 ratio: p<0.05, properdin: p<0.05). Hepatic mRNA expression of factor B and factor D did not differ between subjects with healthy livers and subjects with NASH (factor B: 1.00±0.19 vs. 0.71±0.07, p = 0.26; factor D: 1.00±0.21 vs. 0.66±0.14, p = 0.29;). Hepatic mRNA and protein levels of Decay Accelerating Factor tended to be increased in subjects with NASH (mRNA: 1.00±0.14 vs. 2.37±0.72; p = 0.22; protein: 0.51±0.11 vs. 1.97±0.67; p = 0.28). In contrast, factor H mRNA was downregulated in patients with NASH (1.00±0.09 vs. 0.71±0.06; p<0.05) and a similar trend was observed with hepatic protein levels (1.12±0.16 vs. 0.78±0.07; p = 0.08). Collectively, these data suggest a role for alternative pathway

  6. The Pivotal Role of the Complement System in Aging and Age-related Macular Degeneration: Hypothesis Re-visited

    PubMed Central

    Anderson, Don H.; Radeke, Monte J.; Gallo, Natasha B.; Chapin, Ethan A.; Johnson, Patrick T.; Curletti, Christy R.; Hancox, Lisa S.; Hu, Jane; Ebright, Jessica N.; Malek, Goldis; Hauser, Michael A.; Rickman, Catherine Bowes; Bok, Dean; Hageman, Gregory S.; Johnson, Lincoln V.

    2009-01-01

    During the past ten years, dramatic advances have been made in unraveling the biological bases of age-related macular degeneration (AMD), the most common cause of irreversible blindness in western populations. In that timeframe, two distinct lines of evidence emerged which implicated chronic local inflammation and activation of the complement cascade in AMD pathogenesis. First, a number of complement system proteins, complement activators, and complement regulatory proteins were identified as molecular constituents of drusen, the hallmark extracellular deposits associated with early AMD. Subsequently, genetic studies revealed highly significant statistical associations between AMD and variants of several complement pathway-associated genes including: Complement factor H (CFH), complement factor H-related 1 and 3 (CFHR1 and CFHR3), complement factor B (CFB), complement component 2 (C2), and complement component 3 (C3). In this article, we revisit our original hypothesis that chronic local inflammatory and immune-mediated events at the level of Bruch’s membrane play critical roles in drusen biogenesis and, by extension, in the pathobiology of AMD. Secondly, we report the results of a new screening for additional AMD-associated polymorphisms in a battery of 63 complement-related genes. Third, we identify and characterize the local complement system in the RPE-choroid complex -- thus adding a new dimension of biological complexity to the role of the complement system in ocular aging and AMD. Finally, we evaluate the most salient, recent evidence that bears directly on the role of complement in AMD pathogenesis and progression. Collectively, these recent findings strongly re-affirm the importance of the complement system in AMD. They lay the groundwork for further studies that may lead to the identification of a transcriptional disease signature of AMD, and hasten the development of new therapeutic approaches that will restore the complement-modulating activity that

  7. Interplay between invertebrate C3a with vertebrate macrophages: functional characterization of immune activities of amphioxus C3a.

    PubMed

    Gao, Zhan; Li, Mengyang; Wu, Jie; Zhang, Shicui

    2013-10-01

    Our current knowledge of the structure and function of C3a comes from the study of vertebrate C3a anaphylatoxins, virtually nothing is known about the structure and function of C3a molecules in invertebrates. Here we demonstrated that C3a from the invertebrate chordate Branchiostoma japonicum, BjC3a, was similar to vertebrate C3a possessing potential antibacterial activity, as revealed by sequence analysis and computational modeling. The antibacterial activity of BjC3a was definitely confirmed by both antibacterial assay and TEM observation showing that recombinant BjC3a was directly bactericidal. Additionally, recombinant BjC3a, like vertebrate C3a, was capable of inducing sea bass macrophage migration and enhancing macrophage phagocytosis and respiratory burst response. Moreover, recombinant BjC3a-desArg (generated by removal of the C-terminal arginine), like mammalian C3a-desArg, retained the immunological activities of BjC3a such as antibacterial and respiratory burst-stimulating activities, indicating that the immunological functions of C3a-desArg were conserved throughout chordate evolution. Altogether, our findings show that invertebrate (amphioxus) BjC3a is able to interact with vertebrate (sea bass) macrophages and mediate immune activities, suggesting the emergence of the inflammatory pathway of the complement system similar to that of vertebrates in the basal chordate amphioxus. PMID:23954696

  8. Effector functions of a monoclonal aglycosylated mouse IgG2a: binding and activation of complement component C1 and interaction with human monocyte Fc receptor.

    PubMed

    Leatherbarrow, R J; Rademacher, T W; Dwek, R A; Woof, J M; Clark, A; Burton, D R; Richardson, N; Feinstein, A

    1985-04-01

    Aglycosylated monoclonal anti-DNP mouse IgG2a produced in the presence of tunicamycin was compared with the native monoclonal IgG2a with respect to its ability to interact with the first component of complement, C1, and to compete with human IgG for binding to human monocyte Fc receptors. The aglycosylated IgG2a was found to bind subcomponent C1q with an equivalent capacity to the native IgG2a, but the dissociation constant was found to be increased three-fold. When activation of C1 by the glycosylated and aglycosylated IgG2a was compared, the rate of C1 activation by the aglycosylated IgG2a was reduced approximately three-fold. In contrast aglycosylation was accompanied by a large decrease (greater than or equal to 50-fold) in the apparent binding constant of monomeric IgG2a to human monocytes. The data suggest that the aglycosylated IgG2a has a structure which differs in the CH2 domain from the native IgG2a, and that the heterogeneous N-linked oligosaccharides of this monoclonal IgG2a which occur at a conserved position in the CH2 domain play a role in maintaining the integrity of its monocyte-binding site. This lack of monocyte binding may result either from a localized conformational change occurring in a single CH2 domain or from an alteration in the CH2-CH2 cross-domain architecture which is normally structured by a pair of opposing and interacting oligosaccharides. The minimal changes in C1q binding and C1 activation suggest that the oligosaccharides are, at most, indirectly involved in these events. PMID:4033665

  9. Complement Component C1q Programs a Pro-Efferocytic Phenotype while Limiting TNFα Production in Primary Mouse and Human Macrophages

    PubMed Central

    Hulsebus, Holly J.; O’Conner, Sean D.; Smith, Emily M.; Jie, Chunfa; Bohlson, Suzanne S.

    2016-01-01

    Deficiency in complement component C1q is associated with an inability to clear apoptotic cells (efferocytosis) and aberrant inflammation in lupus, and identification of the pathways involved in these processes should reveal important regulatory mechanisms in lupus and other autoimmune or inflammatory diseases. In this study, C1q-dependent regulation of TNFα/IL-6 expression and efferocytosis was investigated using primary mouse bone marrow-derived macrophages and human monocyte-derived macrophages. C1q downregulated LPS-dependent TNFα production in mouse and human macrophages. While prolonged stimulation with C1q (18 h) was required to elicit a dampening of TNFα production from mouse macrophages, the human macrophages responded to C1q with immediate downregulation of TNFα. IL-6 production was unchanged in mouse and upregulated by human macrophages following prolonged stimulation with C1q. Our previous studies indicated that C1q programmed enhanced efferocytosis in mouse macrophages by enhancing expression of Mer tyrosine kinase and its ligand Gas6, a receptor–ligand pair that also inhibits proinflammatory signaling. Here, we demonstrated that C1q-dependent programming of human macrophage efferocytosis required protein synthesis; however, neither Mer nor the related receptor Axl was upregulated in human cells. In addition, while the C1q-collagen-like tails are sufficient for promoting C1q-dependent phagocytosis of antibody-coated targets, the C1q-tails failed to program enhanced efferocytosis or dampen TNFα production. These data further elucidate the mechanisms by which C1q regulates proinflammatory signaling and efferocytosis in macrophages, functions that are likely to influence the progression of autoimmunity and chronic inflammation. PMID:27379094

  10. The chromosomal order of genes controlling the major histocompatibility complex, properdin factor B, and deficiency of the second component of complement.

    PubMed Central

    Raum, D; Glass, D; Carpenter, C B; Alper, C A; Schur, P H

    1976-01-01

    The relationship of the genes coding for HLA to those coding for properdin Factor B allotypes and for deficiency of the second component of complement (C2) was studied in families of patients with connective tissue disorders. Patients were selected because they were heterozygous or homozygous for C2 deficiency. 12 families with 15 matings informative for C2 deficiency were found. Of 57 informative meioses, two crossovers were noted between the C2 deficiency gene and the HLA-B gene, with a recombinant fraction of 0.035. A lod score of 13 was calculated for linkage between C2 deficiency and HLA-B at a maximum likelihood value of the recombinant fraction of 0.04. 18 families with 21 informative matings for both properdin Factor B allotype and HLA-B were found. Of 72 informative meioses, three recombinants were found, giving a recombinant fraction of 0.042. A lod score of 16 between HLA-B and Factor B allotypes was calculated at a maximum likelihood value of the recombinant fraction of 0.04. A crossover was shown to have occurred between genes for Factor B and HLA-D, in which HLA-D segregared with HLA-A and B. These studies suggest that the genes for Factor B and C2 deficiency are located outside those for HLA, that the order of genese is HLA-A, -B, -D, Factor B allotype, C2 deficiency, that the genes coding for C2 deficiency and Factor B allotypes are approximately 3--5 centimorgans from the HLA-A and HLA-B loci, and that the apparent lack of recombinants between the Factor B gene and C2 deficiency gene suggests that these two genes lie in close proximity to one another. PMID:993342

  11. Anti-complementary constituents of Houttuynia cordata and their targets in complement activation cascade.

    PubMed

    Jiang, Yun; Lu, Yan; Zhang, Yun-Yi; Chen, Dao-Feng

    2014-01-01

    Activity-guided fractionation for complement inhibitors led to the isolation of 23 known compounds from Houttuynia cordata Thunb. Seven flavonoids, two alkaloids, one coumarin and two phenols showed anti-complementary activity. Preliminary inhibitory mechanism of four flavonoids, including quercitrin, afzelin, isoquercitrin and quercetin in the complement activation cascade were examined for the first time. The results indicated that the target components of flavonols are different from those of flavonosides, and the glycoside moieties may be necessary to block C3 and C4 components. PMID:24423008

  12. Contribution of the anaphylatoxin receptors, C3aR and C5aR, to the pathogenesis of pulmonary fibrosis.

    PubMed

    Gu, Hongmei; Fisher, Amanda J; Mickler, Elizabeth A; Duerson, Frank; Cummings, Oscar W; Peters-Golden, Marc; Twigg, Homer L; Woodruff, Trent M; Wilkes, David S; Vittal, Ragini

    2016-06-01

    Complement activation, an integral arm of innate immunity, may be the critical link to the pathogenesis of idiopathic pulmonary fibrosis (IPF). Whereas we have previously reported elevated anaphylatoxins-complement component 3a (C3a) and complement component 5a (C5a)-in IPF, which interact with TGF-β and augment epithelial injury in vitro, their role in IPF pathogenesis remains unclear. The objective of the current study is to determine the mechanistic role of the binding of C3a/C5a to their respective receptors (C3aR and C5aR) in the progression of lung fibrosis. In normal primary human fetal lung fibroblasts, C3a and C5a induces mesenchymal activation, matrix synthesis, and the expression of their respective receptors. We investigated the role of C3aR and C5aR in lung fibrosis by using bleomycin-injured mice with fibrotic lungs, elevated local C3a and C5a, and overexpression of their receptors via pharmacologic and RNA interference interventions. Histopathologic examination revealed an arrest in disease progression and attenuated lung collagen deposition (Masson's trichrome, hydroxyproline, collagen type I α 1 chain, and collagen type I α 2 chain). Pharmacologic or RNA interference-specific interventions suppressed complement activation (C3a and C5a) and soluble terminal complement complex formation (C5b-9) locally and active TGF-β1 systemically. C3aR/C5aR antagonists suppressed local mRNA expressions of tgfb2, tgfbr1/2, ltbp1/2, serpine1, tsp1, bmp1/4, pdgfbb, igf1, but restored the proteoglycan, dcn Clinically, compared with pathologically normal human subjects, patients with IPF presented local induction of C5aR, local and systemic induction of soluble C5b-9, and amplified expression of C3aR/C5aR in lesions. The blockade of C3aR and C5aR arrested the progression of fibrosis by attenuating local complement activation and TGF-β/bone morphologic protein signaling as well as restoring decorin, which suggests a promising therapeutic strategy for patients with

  13. Insights into complement convertase formation based on the structure of the factor B-cobra venom factor complex

    PubMed Central

    Janssen, Bert J C; Gomes, Lucio; Koning, Roman I; Svergun, Dmitri I; Koster, Abraham J; Fritzinger, David C; Vogel, Carl-Wilhelm; Gros, Piet

    2009-01-01

    Immune protection by the complement system critically depends on assembly of C3 convertases on the surface of pathogens and altered host cells. These short-lived protease complexes are formed through pro-convertases, which for the alternative pathway consist of the complement component C3b and the pro-enzyme factor B (FB). Here, we present the crystal structure at 2.2-Å resolution, small-angle X-ray scattering and electron microscopy (EM) data of the pro-convertase formed by human FB and cobra venom factor (CVF), a potent homologue of C3b that generates more stable convertases. FB is loaded onto CVF through its pro-peptide Ba segment by specific contacts, which explain the specificity for the homologous C3b over the native C3 and inactive products iC3b and C3c. The protease segment Bb binds the carboxy terminus of CVF through the metal-ion dependent adhesion site of the Von Willebrand factor A-type domain. A possible dynamic equilibrium between a ‘loading' and ‘activation' state of the pro-convertase may explain the observed difference between the crystal structure of CVFB and the EM structure of C3bB. These insights into formation of convertases provide a basis for further development of complement therapeutics. PMID:19574954

  14. Anti-complement activity of the Ixodes scapularis salivary protein Salp20.

    PubMed

    Hourcade, Dennis E; Akk, Antonina M; Mitchell, Lynne M; Zhou, Hui-fang; Hauhart, Richard; Pham, Christine T N

    2016-01-01

    Complement, a major component of innate immunity, presents a rapid and robust defense of the intravascular space. While regulatory proteins protect host cells from complement attack, when these measures fail, unrestrained complement activation may trigger self-tissue injury, leading to pathologic conditions. Of the three complement activation pathways, the alternative pathway (AP) in particular has been implicated in numerous disease and injury states. Consequently, the AP components represent attractive targets for therapeutic intervention. The common hard-bodied ticks from the family Ixodidae derive nourishment from the blood of their mammalian hosts. During its blood meal the tick is exposed to host immune effectors, including the complement system. In defense, the tick produces salivary proteins that can inhibit host immune functions. The Salp20 salivary protein of Ixodes scapularis inhibits the host AP pathway by binding properdin and dissociating C3bBbP, the active C3 convertase. In these studies we examined Salp20 activity in various complement-mediated pathologies. Our results indicate that Salp20 can inhibit AP-dependent pathogenesis in the mouse. Its efficacy may be part in due to synergic effects it provides with the endogenous AP regulator, factor H. While Salp20 itself would be expected to be highly immunogenic and therefore inappropriate for therapeutic use, its emergence speaks for the potential development of a non-immunogenic Salp20 mimic that replicates its anti-properdin activity. PMID:26675068

  15. C3 deficiency ameliorates the negative effects of irradiation of the young brain on hippocampal development and learning.

    PubMed

    Kalm, Marie; Andreasson, Ulf; Björk-Eriksson, Thomas; Zetterberg, Henrik; Pekny, Milos; Blennow, Kaj; Pekna, Marcela; Blomgren, Klas

    2016-04-12

    Radiotherapy in the treatment of pediatric brain tumors is often associated with debilitating late-appearing adverse effects, such as intellectual impairment. Areas in the brain harboring stem cells are particularly sensitive to irradiation (IR) and loss of these cells may contribute to cognitive deficits. It has been demonstrated that IR-induced inflammation negatively affects neural progenitor differentiation. In this study, we used mice lacking the third complement component (C3-/-) to investigate the role of complement in a mouse model of IR-induced injury to the granule cell layer (GCL) of the hippocampus. C3-/- and wild type (WT) mice received a single, moderate dose of 8 Gy to the brain on postnatal day 10. The C3-/- mice displayed 55 % more microglia (Iba-1+) and a trend towards increase in proliferating cells in the GCL compared to WT mice 7 days after IR. Importantly, months after IR C3-/- mice made fewer errors than WT mice in a reversal learning test indicating better learning capacity in C3-/- mice after IR. Notably, months after IR C3-/- and WT mice had similar GCL volumes, survival of newborn cells (BrdU), microglia (Iba-1) and astrocyte (S100β) numbers in the GCL. In summary, our data show that the complement system contributes to IR-induced loss of proliferating cells and maladaptive inflammatory responses in the acute phase after IR, leading to impaired learning capacity in adulthood. Targeting the complement system is hence promising for future strategies to reduce the long-term adverse consequences of IR in the young brain. PMID:27029069

  16. C3 deficiency ameliorates the negative effects of irradiation of the young brain on hippocampal development and learning

    PubMed Central

    Kalm, Marie; Andreasson, Ulf; Björk-Eriksson, Thomas; Zetterberg, Henrik; Pekny, Milos; Blennow, Kaj; Pekna, Marcela; Blomgren, Klas

    2016-01-01

    Radiotherapy in the treatment of pediatric brain tumors is often associated with debilitating late-appearing adverse effects, such as intellectual impairment. Areas in the brain harboring stem cells are particularly sensitive to irradiation (IR) and loss of these cells may contribute to cognitive deficits. It has been demonstrated that IR-induced inflammation negatively affects neural progenitor differentiation. In this study, we used mice lacking the third complement component (C3−/−) to investigate the role of complement in a mouse model of IR-induced injury to the granule cell layer (GCL) of the hippocampus. C3−/− and wild type (WT) mice received a single, moderate dose of 8 Gy to the brain on postnatal day 10. The C3−/− mice displayed 55 % more microglia (Iba-1+) and a trend towards increase in proliferating cells in the GCL compared to WT mice 7 days after IR. Importantly, months after IR C3−/− mice made fewer errors than WT mice in a reversal learning test indicating better learning capacity in C3−/− mice after IR. Notably, months after IR C3−/− and WT mice had similar GCL volumes, survival of newborn cells (BrdU), microglia (Iba-1) and astrocyte (S100β) numbers in the GCL. In summary, our data show that the complement system contributes to IR-induced loss of proliferating cells and maladaptive inflammatory responses in the acute phase after IR, leading to impaired learning capacity in adulthood. Targeting the complement system is hence promising for future strategies to reduce the long-term adverse consequences of IR in the young brain. PMID:27029069

  17. Artepillin C, a Typical Brazilian Propolis-Derived Component, Induces Brown-Like Adipocyte Formation in C3H10T1/2 Cells, Primary Inguinal White Adipose Tissue-Derived Adipocytes, and Mice.

    PubMed

    Nishikawa, Sho; Aoyama, Hiroki; Kamiya, Misa; Higuchi, Jun; Kato, Aiko; Soga, Minoru; Kawai, Taeko; Yoshimura, Kazuki; Kumazawa, Shigenori; Tsuda, Takanori

    2016-01-01

    Induction of brown-like adipocytes (beige/brite cells) in white adipose tissue (WAT) suggests a new approach for preventing and treating obesity via induction of thermogenesis associated with uncoupling protein 1 (UCP1). However, whether diet-derived factors can directly induce browning of white adipocytes has not been well established. In addition, the underlying mechanism of induction of brown-like adipocytes by diet-derived factors has been unclear. Here, we demonstrate that artepillin C (ArtC), which is a typical Brazilian propolis-derived component, significantly induces brown-like adipocytes in murine C3H10T1/2 cells and primary inguinal WAT (iWAT)-derived adipocytes. This significant induction is due to activation of peroxisome proliferator-activated receptor γ and stabilization of PRD1-BF-1-RIZ1 homologous domain-containing protein-16 (PRDM16). Furthermore, the oral administration of ArtC (10 mg/kg) for 4 weeks significantly induced brown-like adipocytes accompanied by significant expression of UCP1 and PRDM16 proteins in iWAT of mice, and was independent of the β3-adrenergic signaling pathway via the sympathetic nervous system. These findings may provide insight into browning of white adipocytes including the molecular mechanism mediated by dietary factors and demonstrate that ArtC has a novel biological function with regard to increasing energy expenditure by browning of white adipocytes. PMID:27598888

  18. Complement factor H–related hybrid protein deregulates complement in dense deposit disease

    PubMed Central

    Chen, Qian; Wiesener, Michael; Eberhardt, Hannes U.; Hartmann, Andrea; Uzonyi, Barbara; Kirschfink, Michael; Amann, Kerstin; Buettner, Maike; Goodship, Tim; Hugo, Christian; Skerka, Christine; Zipfel, Peter F.

    2013-01-01

    The renal disorder C3 glomerulopathy with dense deposit disease (C3G-DDD) pattern results from complement dysfunction and primarily affects children and young adults. There is no effective treatment, and patients often progress to end-stage renal failure. A small fraction of C3G-DDD cases linked to factor H or C3 gene mutations as well as autoantibodies have been reported. Here, we examined an index family with 2 patients with C3G-DDD and identified a chromosomal deletion in the complement factor H–related (CFHR) gene cluster. This deletion resulted in expression of a hybrid CFHR2-CFHR5 plasma protein. The recombinant hybrid protein stabilized the C3 convertase and reduced factor H–mediated convertase decay. One patient was refractory to plasma replacement and exchange therapy, as evidenced by the hybrid protein quickly returning to pretreatment plasma levels. Subsequently, complement inhibitors were tested on serum from the patient for their ability to block activity of CFHR2-CFHR5. Soluble CR1 restored defective C3 convertase regulation; however, neither eculizumab nor tagged compstatin had any effect. Our findings provide insight into the importance of CFHR proteins for C3 convertase regulation and identify a genetic variation in the CFHR gene cluster that promotes C3G-DDD. Monitoring copy number and sequence variations in the CFHR gene cluster in C3G-DDD and kidney patients with C3G-DDD variations will help guide treatment strategies. PMID:24334459

  19. Intranasal peptide-induced tolerance and linked suppression: consequences of complement deficiency.

    PubMed

    Fossati-Jimack, Liliane; Ling, Guang Sheng; Baudino, Lucie; Szajna, Marta; Manivannan, Kiruthika; Zhao, Jade Chen; Midgley, Robert; Chai, Jian-Guo; Simpson, Elizabeth; Botto, Marina; Scott, Diane

    2015-01-01

    A role for complement, particularly the classical pathway, in the regulation of immune responses is well documented. Deficiencies in C1q or C4 predispose to autoimmunity, while deficiency in C3 affects the suppression of contact sensitization and generation of oral tolerance. Complement components including C3 have been shown to be required for both B-cell and T-cell priming. The mechanisms whereby complement can mediate these diverse regulatory effects are poorly understood. Our previous work, using the mouse minor histocompatibility (HY) model of skin graft rejection, showed that both C1q and C3 were required for the induction of tolerance following intranasal peptide administration. By comparing tolerance induction in wild-type C57BL/6 and C1q-, C3-, C4- and C5-deficient C57BL/6 female mice, we show here that the classical pathway components including C3 are required for tolerance induction, whereas C5 plays no role. C3-deficient mice failed to generate a functional regulatory T (Treg) -dendritic cell (DC) tolerogenic loop required for tolerance induction. This was related to the inability of C3-deficient DC to up-regulate the arginine-consuming enzyme, inducible nitric oxide synthase (Nos-2), in the presence of antigen-specific Treg cells and peptide, leading to reduced Treg cell generation. Our findings demonstrate that the classical pathway and C3 play a critical role in the peptide-mediated induction of tolerance to HY by modulating DC function. PMID:25039245

  20. Intranasal peptide-induced tolerance and linked suppression: consequences of complement deficiency

    PubMed Central

    Fossati-Jimack, Liliane; Ling, Guang Sheng; Baudino, Lucie; Szajna, Marta; Manivannan, Kiruthika; Zhao, Jade Chen; Midgley, Robert; Chai, Jian-Guo; Simpson, Elizabeth; Botto, Marina; Scott, Diane

    2015-01-01

    A role for complement, particularly the classical pathway, in the regulation of immune responses is well documented. Deficiencies in C1q or C4 predispose to autoimmunity, while deficiency in C3 affects the suppression of contact sensitization and generation of oral tolerance. Complement components including C3 have been shown to be required for both B-cell and T-cell priming. The mechanisms whereby complement can mediate these diverse regulatory effects are poorly understood. Our previous work, using the mouse minor histocompatibility (HY) model of skin graft rejection, showed that both C1q and C3 were required for the induction of tolerance following intranasal peptide administration. By comparing tolerance induction in wild-type C57BL/6 and C1q-, C3-, C4- and C5-deficient C57BL/6 female mice, we show here that the classical pathway components including C3 are required for tolerance induction, whereas C5 plays no role. C3-deficient mice failed to generate a functional regulatory T (Treg) –dendritic cell (DC) tolerogenic loop required for tolerance induction. This was related to the inability of C3-deficient DC to up-regulate the arginine-consuming enzyme, inducible nitric oxide synthase (Nos-2), in the presence of antigen-specific Treg cells and peptide, leading to reduced Treg cell generation. Our findings demonstrate that the classical pathway and C3 play a critical role in the peptide-mediated induction of tolerance to HY by modulating DC function. PMID:25039245

  1. Skin Injuries Reduce Survival and Modulate Corticosterone, C-Reactive Protein, Complement Component 3, IgM, and Prostaglandin E2 after Whole-Body Reactor-Produced Mixed Field (n + γ-Photons) Irradiation

    PubMed Central

    Kiang, Juliann G.; Ledney, G. David

    2013-01-01

    Skin injuries such as wounds or burns following whole-body γ-irradiation (radiation combined injury (RCI)) increase mortality more than whole-body γ-irradiation alone. Wound-induced decreases in survival after irradiation are triggered by sustained activation of inducible nitric oxide synthase pathways, persistent alteration of cytokine homeostasis, and increased susceptibility to systemic bacterial infection. Among these factors, radiation-induced increases in interleukin-6 (IL-6) concentrations in serum were amplified by skin wound trauma. Herein, the IL-6-induced stress proteins including C-reactive protein (CRP), complement 3 (C3), immunoglobulin M (IgM), and prostaglandin E2 (PGE2) were evaluated after skin injuries given following a mixed radiation environment that might be found after a nuclear incident. In this report, mice received 3 Gy of reactor-produced mixed field (n + γ-photons) radiations at 0.38 Gy/min followed by nonlethal skin wounding or burning. Both wounds and burns reduced survival and increased CRP, C3, and PGE2 in serum after radiation. Decreased IgM production along with an early rise in corticosterone followed by a subsequent decrease was noted for each RCI situation. These results suggest that RCI-induced alterations of corticosterone, CRP, C3, IgM, and PGE2 cause homeostatic imbalance and may contribute to reduced survival. Agents inhibiting these responses may prove to be therapeutic for RCI and improve related survival. PMID:24175013

  2. Kidney transplant outcomes in familial C3 glomerulopathy

    PubMed Central

    Wong, Limy; Moran, Sarah; Lavin, Peter J.; Dorman, Anthony M.; Conlon, Peter J.

    2016-01-01

    C3 glomerulopathy, a newly designated entity, is characterized by glomerular disease associated with dysregulation of the alternative complement pathway and is a rare cause of end-stage kidney disease. Overall disease characteristics that include clinical presentation, laboratory assessment, histopathology and genetic background have only been unravelled in recent years and have led to the development of anti-complement therapies targeting different levels of the alternative pathway. We describe the long-term outcomes following kidney transplantation in an Irish family with familial C3 glomerulopathy due to a hybrid CFHR3-1 gene. PMID:27274824

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

    PubMed Central

    Li, Jing; Ge, Xin; Wang, Xiaona; Liu, Xiao; Ma, Jianmin

    2016-01-01

    Objective We aimed to examine the potential involvement of local complement system gene expression in the pathogenesis of benign lymphoepithelial lesions (BLEL) of the lacrimal gland. Methods We collected data from 9 consecutive pathologically confirmed patients with BLEL of the lacrimal gland and 9 cases with orbital cavernous hemangioma as a control group, and adopted whole genome microarray to screen complement system-related differential genes, followed by RT-PCR verification and in-depth enrichment analysis (Gene Ontology analysis) of the gene sets. Results The expression of 14 complement system-related genes in the pathologic tissue, including C2, C3, ITGB2, CR2, C1QB, CR1, ITGAX, CFP, C1QA, C4B|C4A, FANCA, C1QC, C3AR1 and CFHR4, were significantly upregulated while 7 other complement system-related genes, C5, CFI, CFHR1|CFH, CFH, CD55, CR1L and CFD were significantly downregulated in the lacrimal glands of BLEL patients. The microarray results were consistent with RT-PCR analysis results. Immunohistochemistry analysis of C3c and C1q complement component proteins in the resected tissue were positive in BLEL patients, while the control group had negative expression of these proteins. Gene ontology (GO) analysis revealed that activation of the genes of complement system-mediated signaling pathways were the most enriched differential gene group in BLEL patients. Conclusions Local expression of complement components is prominently abnormal in BLEL, and may well play a role in its pathogenesis. PMID:26849056

  4. Cardiac dysfunction caused by purified human C3a anaphylatoxin.

    PubMed Central

    del Balzo, U H; Levi, R; Polley, M J

    1985-01-01

    The purpose of this investigation was to define the cardiac effects of complement-derived C3a anaphylatoxin, in view of the possibility that cardiac dysfunction may occur as a result of complement activation. Purified human C3a was administered by intracoronary bolus injections into isolated guinea pig hearts. As a function of dose, C3a caused tachycardia, impairment of atrioventricular conduction, left ventricular contractile failure, coronary vasoconstriction, and histamine release. These effects were abolished by cleavage of the COOH-terminal arginine by carboxypeptidase B. The magnitude of C3a-induced tachycardia correlated with the amount of endogenous cardiac histamine released into the coronary effluent. Whereas the tachycardia was markedly reduced by the histamine H2 antagonist cimetidine, the contractile failure and the coronary vasoconstriction caused by C3a were antagonized by the leukotriene antagonist FPL 55712 and by the cyclooxygenase inhibitor indomethacin, respectively. This suggests that histamine, leukotrienes, and vasoactive prostanoates may mediate the various cardiac effects of C3a. Our findings indicate that C3a anaphylatoxin has marked cardiac effects at concentrations that are likely to be attained with a degree of C3 activation commonly seen in various disease states. Thus, our data are compatible with the hypothesis that generation of anaphylatoxins may induce cardiac dysfunction in clinical conditions. PMID:2579381

  5. Differential mechanisms of complement-mediated neutralization of the closely related paramyxoviruses simian virus 5 and mumps virus

    PubMed Central

    Johnson, John B.; Capraro, Gerald A.; Parks, Griffith D.

    2008-01-01

    The complement system is an important component of the innate immune response to virus infection. The role of human complement pathways in the in vitro neutralization of three closely related paramyxoviruses, Simian Virus 5 (SV5), Mumps virus (MuV) and Human Parainfluenza virus type 2 (HPIV2) was investigated. Sera from ten donors showed high levels of neutralization against HPIV2 that was largely complement-independent, whereas nine of ten donor sera were found to neutralize SV5 and MuV only in the presence of active complement pathways. SV5 and MuV neutralization proceeded through the alternative pathway of the complement cascade. Electron microscopy studies and biochemical analyses showed that treatment of purified SV5 with human serum resulted in C3 deposition on virions and the formation of massive aggregates, but there was relatively little evidence of virion lysis. Treatment of MuV with human serum also resulted in C3 deposition on virions, however in contrast to SV5, MuV particles were lysed by serum complement and there was relatively little aggregation. Assays using serum depleted of complement factors showed that SV5 and MuV neutralization in vitro was absolutely dependent on complement factor C3, but was not dependent on downstream complement factors C5 or C8. Our results indicate that even though antibodies exist that recognize both SV5 and MuV, they are mostly non-neutralizing and viral inactivation in vitro occurs through the alternative pathway of complement. The implications of our work for development of paramyxovirus vectors and vaccines are discussed. PMID:18440578

  6. Differential mechanisms of complement-mediated neutralization of the closely related paramyxoviruses simian virus 5 and mumps virus

    SciTech Connect

    Johnson, John B.; Capraro, Gerald A.; Parks, Griffith D.

    2008-06-20

    The complement system is an important component of the innate immune response to virus infection. The role of human complement pathways in the in vitro neutralization of three closely related paramyxoviruses, Simian Virus 5 (SV5), Mumps virus (MuV) and Human Parainfluenza virus type 2 (HPIV2) was investigated. Sera from ten donors showed high levels of neutralization against HPIV2 that was largely complement-independent, whereas nine of ten donor sera were found to neutralize SV5 and MuV only in the presence of active complement pathways. SV5 and MuV neutralization proceeded through the alternative pathway of the complement cascade. Electron microscopy studies and biochemical analyses showed that treatment of purified SV5 with human serum resulted in C3 deposition on virions and the formation of massive aggregates, but there was relatively little evidence of virion lysis. Treatment of MuV with human serum also resulted in C3 deposition on virions, however in contrast to SV5, MuV particles were lysed by serum complement and there was relatively little aggregation. Assays using serum depleted of complement factors showed that SV5 and MuV neutralization in vitro was absolutely dependent on complement factor C3, but was not dependent on downstream complement factors C5 or C8. Our results indicate that even though antibodies exist that recognize both SV5 and MuV, they are mostly non-neutralizing and viral inactivation in vitro occurs through the alternative pathway of complement. The implications of our work for development of paramyxovirus vectors and vaccines are discussed.

  7. Cutting edge: the NLRP3 inflammasome links complement-mediated inflammation and IL-1β release.

    PubMed

    Laudisi, Federica; Spreafico, Roberto; Evrard, Maximilien; Hughes, Timothy R; Mandriani, Barbara; Kandasamy, Matheswaran; Morgan, B Paul; Sivasankar, Baalasubramanian; Mortellaro, Alessandra

    2013-08-01

    The complement system is a potent component of the innate immune response, promoting inflammation and orchestrating defense against pathogens. However, dysregulation of complement is critical to several autoimmune and inflammatory syndromes. Elevated expression of the proinflammatory cytokine IL-1β is often linked to such diseases. In this study, we reveal the mechanistic link between complement and IL-1β secretion using murine dendritic cells. IL-1β secretion occurs following intracellular caspase-1 activation by inflammasomes. We show that complement elicits secretion of both IL-1β and IL-18 in vitro and in vivo via the NLRP3 inflammasome. This effect depends on the inflammasome components NLRP3 and ASC, as well as caspase-1 activity. Interestingly, sublethal complement membrane attack complex formation, but not the anaphylatoxins C3a and C5a, activated the NLRP3 inflammasome in vivo. These findings provide insight into the molecular processes underlying complement-mediated inflammation and highlight the possibility of targeting IL-1β to control complement-induced disease and pathological inflammation. PMID:23817414

  8. Cutting Edge: The NLRP3 Inflammasome Links Complement-Mediated Inflammation and IL-1β Release

    PubMed Central

    Laudisi, Federica; Spreafico, Roberto; Evrard, Maximilien; Hughes, Timothy R.; Mandriani, Barbara; Kandasamy, Matheswaran; Morgan, B. Paul; Sivasankar, Baalasubramanian

    2013-01-01

    The complement system is a potent component of the innate immune response, promoting inflammation and orchestrating defense against pathogens. However, dysregulation of complement is critical to several autoimmune and inflammatory syndromes. Elevated expression of the proinflammatory cytokine IL-1β is often linked to such diseases. In this study, we reveal the mechanistic link between complement and IL-1β secretion using murine dendritic cells. IL-1β secretion occurs following intracellular caspase-1 activation by inflammasomes. We show that complement elicits secretion of both IL-1β and IL-18 in vitro and in vivo via the NLRP3 inflammasome. This effect depends on the inflammasome components NLRP3 and ASC, as well as caspase-1 activity. Interestingly, sublethal complement membrane attack complex formation, but not the anaphylatoxins C3a and C5a, activated the NLRP3 inflammasome in vivo. These findings provide insight into the molecular processes underlying complement-mediated inflammation and highlight the possibility of targeting IL-1β to control complement-induced disease and pathological inflammation. PMID:23817414

  9. Complement-derived leukotactic factors in inflammatory synovial fluids of humans

    PubMed Central

    Ward, Peter A.; Zvaifler, Nathan J.

    1971-01-01

    A large per cent of rheumatoid synovial fluids contain chemotactic activity for rabbit granulocytes (neutrophilic). The chemotactic activity is, in large part, related to the fifth (C5) and sixth (C6) components of human complement; a combination of physical-chemical techniques indicates the activity to be attributable to C567 and C5a, a cleavage product of C5. Many rheumatoid synovial fluids contain a C5-cleaving enzyme which, on the basis of substrate specificity and susceptibility to inhibitors, is very similar to an enzyme extractable from lysosomal granules of human and rabbit granulocytes. Inflammatory nonrheumatoid synovial fluids contain chemotactic activity that is related to cleavage products (C3a) of the third component of human complement (C3). Also found in these fluids is a C3-cleaving enzyme capable of producing C3a. Of the other synovial fluids examined, lupus fluids were remarkable by their total lack of chemotactic activity. These findings record for the first time the presence of complement-derived chemotactic factors in pathological human fluids. Images PMID:5545123

  10. Electrostatic Steering Accelerates C3d:CR2 Association.

    PubMed

    Mohan, Rohith R; Huber, Gary A; Morikis, Dimitrios

    2016-08-25

    Electrostatic effects are ubiquitous in protein interactions and are found to be pervasive in the complement system as well. The interaction between complement fragment C3d and complement receptor 2 (CR2) has evolved to become a link between innate and adaptive immunity. Electrostatic interactions have been suggested to be the driving factor for the association of the C3d:CR2 complex. In this study, we investigate the effects of ionic strength and mutagenesis on the association of C3d:CR2 through Brownian dynamics simulations. We demonstrate that the formation of the C3d:CR2 complex is ionic strength-dependent, suggesting the presence of long-range electrostatic steering that accelerates the complex formation. Electrostatic steering occurs through the interaction of an acidic surface patch in C3d and the positively charged CR2 and is supported by the effects of mutations within the acidic patch of C3d that slow or diminish association. Our data are in agreement with previous experimental mutagenesis and binding studies and computational studies. Although the C3d acidic patch may be locally destabilizing because of unfavorable Coulombic interactions of like charges, it contributes to the acceleration of association. Therefore, acceleration of function through electrostatic steering takes precedence to stability. The site of interaction between C3d and CR2 has been the target for delivery of CR2-bound nanoparticle, antibody, and small molecule biomarkers, as well as potential therapeutics. A detailed knowledge of the physicochemical basis of C3d:CR2 association may be necessary to accelerate biomarker and drug discovery efforts. PMID:27092816

  11. Streptococcus pyogenes Employs Strain-dependent Mechanisms of C3b Inactivation to Inhibit Phagocytosis and Killing of Bacteria.

    PubMed

    Agrahari, Garima; Liang, Zhong; Glinton, Kristofor; Lee, Shaun W; Ploplis, Victoria A; Castellino, Francis J

    2016-04-22

    Evasion of complement-mediated opsonophagocytosis enables group A Streptococcus pyogenes (GAS) to establish infection. Different strain-dependent mechanisms are employed by the host to accomplish this goal. In general, GAS inhibits the amplification of the complement cascade on its cell surface by facilitating the degradation of C3b, an opsonin, to an inactive product, inactivated C3b (iC3b), in a step catalyzed by factor I (FI) and its cofactor, factor H (FH), with or without the participation of human host plasmin (hPm). GAS recruits FH to its cell surface via FH receptors, which are transcriptionally controlled by the two-component cluster of virulence responder-sensor system. The manner in which FI-FH and hPm function together on GAS cells is unknown. Using GAS strain AP53, which strongly binds host human plasminogen/plasmin (hPg/hPm) directly via an hPg/hPm surface receptor (PAM), we show that both FI-FH and hPm sequentially cleave C3b. Whereas FI-FH proteolytically cleaves C3b into iC3b, PAM-bound hPm catalyzes cleavage of iC3b into multiple smaller peptides. Unlike AP53, GAS strain M23ND weakly binds FH and recruits hPg/hPm to its cell surface indirectly via fibrinogen bound to M-protein, M23. In this case, FH-FI cleaves C3b into iC3b, with negligible degradation of iC3b by hPm that is bound to fibrinogen on the cells. AP53 and M23ND display similar resistance to human neutrophil-mediated phagocytosis, which results in a corresponding high lethality in mice after injection of these cells. These results suggest that GAS utilizes diverse mechanisms to degrade C3b and thus to protect bacterial cells from the complement response of the host. PMID:26945067

  12. Infections of People with Complement Deficiencies and Patients Who Have Undergone Splenectomy

    PubMed Central

    Ram, Sanjay; Lewis, Lisa A.; Rice, Peter A.

    2010-01-01

    Summary: The complement system comprises several fluid-phase and membrane-associated proteins. Under physiological conditions, activation of the fluid-phase components of complement is maintained under tight control and complement activation occurs primarily on surfaces recognized as “nonself” in an attempt to minimize damage to bystander host cells. Membrane complement components act to limit complement activation on host cells or to facilitate uptake of antigens or microbes “tagged” with complement fragments. While this review focuses on the role of complement in infectious diseases, work over the past couple of decades has defined several important functions of complement distinct from that of combating infections. Activation of complement in the fluid phase can occur through the classical, lectin, or alternative pathway. Deficiencies of components of the classical pathway lead to the development of autoimmune disorders and predispose individuals to recurrent respiratory infections and infections caused by encapsulated organisms, including Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. While no individual with complete mannan-binding lectin (MBL) deficiency has been identified, low MBL levels have been linked to predisposition to, or severity of, several diseases. It appears that MBL may play an important role in children, who have a relatively immature adaptive immune response. C3 is the point at which all complement pathways converge, and complete deficiency of C3 invariably leads to severe infections, including those caused by meningococci and pneumococci. Deficiencies of the alternative and terminal complement pathways result in an almost exclusive predisposition to invasive meningococcal disease. The spleen plays an important role in antigen processing and the production of antibodies. Splenic macrophages are critical in clearing opsonized encapsulated bacteria (such as pneumococci, meningococci, and Escherichia coli

  13. The Structure-Function Relationships of Complement Receptor Type 2 (CR2; CD21).

    PubMed

    Hannan, Jonathan Paul

    2016-01-01

    Human complement receptor type 2 (CR2; CD21) is a surface-associated glycoprotein which binds to a variety of endogenous ligands, including the complement component C3 fragments iC3b, C3dg and C3d, the low-affinity IgE receptor CD23, and the type I cytokine, interferon-alpha. CR2 links the innate complement-mediated immune response to pathogens and foreign antigens with the adaptive immune response by binding to C3d that is covalently attached to targets, and which results in a cell signalling phenomenon that lowers the threshold for B cell activation. Variations or deletions of the CR2 gene in humans, or the Cr2 gene in mice associate with a variety of autoimmune and inflammatory conditions. A number of infectious agents including Epstein-Barr virus (EBV), Human Immunodeficiency Virus (HIV) and prions also bind to CR2 either directly or indirectly by means of C3d-targeted immune complexes. In this review we discuss the interactions that CR2 undertakes with its best characterized ligands C3d, CD23 and the EBV gp350/220 envelope protein. To date only a single physiologically relevant complex of CR2 with one of its ligands, C3d, has been elucidated. By contrast, the interactions with CD23 and EBV gp350/220, while being important from physiologic and disease-associated standpoints, respectively, are only incompletely understood. A detailed knowledge of the structure-function relationships that CR2 undergoes with its ligands is necessary to understand the implications of using recombinant CR2 in therapeutic or imaging agents, or alternatively targeting CR2 to down-regulate the antibody mediated immune response in cases of autoimmunity. PMID:26916158

  14. Complement Activation and Inhibition in Wound Healing

    PubMed Central

    Cazander, Gwendolyn; Jukema, Gerrolt N.; Nibbering, Peter H.

    2012-01-01

    Complement activation is needed to restore tissue injury; however, inappropriate activation of complement, as seen in chronic wounds can cause cell death and enhance inflammation, thus contributing to further injury and impaired wound healing. Therefore, attenuation of complement activation by specific inhibitors is considered as an innovative wound care strategy. Currently, the effects of several complement inhibitors, for example, the C3 inhibitor compstatin and several C1 and C5 inhibitors, are under investigation in patients with complement-mediated diseases. Although (pre)clinical research into the effects of these complement inhibitors on wound healing is limited, available data indicate that reduction of complement activation can improve wound healing. Moreover, medicine may take advantage of safe and effective agents that are produced by various microorganisms, symbionts, for example, medicinal maggots, and plants to attenuate complement activation. To conclude, for the development of new wound care strategies, (pre)clinical studies into the roles of complement and the effects of application of complement inhibitors in wound healing are required. PMID:23346185

  15. Meningococcal disease and the complement system

    PubMed Central

    Lewis, Lisa A; Ram, Sanjay

    2014-01-01

    Despite considerable advances in the understanding of the pathogenesis of meningococcal disease, this infection remains a major cause of morbidity and mortality globally. The role of the complement system in innate immune defenses against invasive meningococcal disease is well established. Individuals deficient in components of the alternative and terminal complement pathways are highly predisposed to invasive, often recurrent meningococcal infections. Genome-wide analysis studies also point to a central role for complement in disease pathogenesis. Here we review the pathophysiologic events pertinent to the complement system that accompany meningococcal sepsis in humans. Meningococci use several often redundant mechanisms to evade killing by human complement. Capsular polysaccharide and lipooligosaccharide glycan composition play critical roles in complement evasion. Some of the newly described protein vaccine antigens interact with complement components and have sparked considerable research interest. PMID:24104403

  16. Hepatitis B virus X protein binding to hepsin promotes C3 production by inducing IL-6 secretion from hepatocytes.

    PubMed

    Zhang, Mingming; Gu, Jianxin; Zhang, Chunyi

    2016-02-16

    Hepatitis B virus (HBV) X protein (HBx) is an important effector for HBV-associated pathogenesis. In this study, we identified hepsin as an HBx-interacting protein and investigated the effects of hepsin on HBx-mediated complement component 3 (C3) secretion in hepatocytes. In vivo and in vitro binding between HBx and hepsin was confirmed by co-immunoprecipitation and Glutathione S-transferase pull-down assays. HBx synergized with hepsin to promote C3 production by potentiating interleukin-6 (IL-6) secretion. Knockdown of endogenous hepsin attenuated C3 and IL-6 secretion induced by HBx in hepatic cells. In addition, levels of hepsin protein correlated positively with C3 expression in human non-tumor liver tissues. Further exploration revealed that HBx and hepsin increased C3 promoter activity by up-regulating the expression and phosphorylation of the transcription factor CAAT/enhancer binding protein beta (C/EBP-β), which binds to the IL-6/IL-1 response element in the C3 promoter. HBx and hepsin synergistically enhanced IL-6 mRNA levels and promoter activity by increasing the nuclear translocation of nuclear factor kappaB (NF-κB). Our findings show for the first time that binding between HBx and hepsin promotes C3 production by inducing IL-6 secretion in hepatocytes. PMID:26760961

  17. Hepatitis B virus X protein binding to hepsin promotes C3 production by inducing IL-6 secretion from hepatocytes

    PubMed Central

    Zhang, Mingming; Gu, Jianxin; Zhang, Chunyi

    2016-01-01

    Hepatitis B virus (HBV) X protein (HBx) is an important effector for HBV-associated pathogenesis. In this study, we identified hepsin as an HBx-interacting protein and investigated the effects of hepsin on HBx-mediated complement component 3 (C3) secretion in hepatocytes. In vivo and in vitro binding between HBx and hepsin was confirmed by co-immunoprecipitation and Glutathione S-transferase pull-down assays. HBx synergized with hepsin to promote C3 production by potentiating interleukin-6 (IL-6) secretion. Knockdown of endogenous hepsin attenuated C3 and IL-6 secretion induced by HBx in hepatic cells. In addition, levels of hepsin protein correlated positively with C3 expression in human non-tumor liver tissues. Further exploration revealed that HBx and hepsin increased C3 promoter activity by up-regulating the expression and phosphorylation of the transcription factor CAAT/enhancer binding protein beta (C/EBP-β), which binds to the IL-6/IL-1 response element in the C3 promoter. HBx and hepsin synergistically enhanced IL-6 mRNA levels and promoter activity by increasing the nuclear translocation of nuclear factor kappaB (NF-κB). Our findings show for the first time that binding between HBx and hepsin promotes C3 production by inducing IL-6 secretion in hepatocytes. PMID:26760961

  18. The complement system and adverse pregnancy outcomes.

    PubMed

    Regal, Jean F; Gilbert, Jeffrey S; Burwick, Richard M

    2015-09-01

    Adverse pregnancy outcomes significantly contribute to morbidity and mortality for mother and child, with lifelong health consequences for both. The innate and adaptive immune system must be regulated to insure survival of the fetal allograft, and the complement system is no exception. An intact complement system optimizes placental development and function and is essential to maintain host defense and fetal survival. Complement regulation is apparent at the placental interface from early pregnancy with some degree of complement activation occurring normally throughout gestation. However, a number of pregnancy complications including early pregnancy loss, fetal growth restriction, hypertensive disorders of pregnancy and preterm birth are associated with excessive or misdirected complement activation, and are more frequent in women with inherited or acquired complement system disorders or complement gene mutations. Clinical studies employing complement biomarkers in plasma and urine implicate dysregulated complement activation in components of each of the adverse pregnancy outcomes. In addition, mechanistic studies in rat and mouse models of adverse pregnancy outcomes address the complement pathways or activation products of importance and allow critical analysis of the pathophysiology. Targeted complement therapeutics are already in use to control adverse pregnancy outcomes in select situations. A clearer understanding of the role of the complement system in both normal pregnancy and complicated or failed pregnancy will allow a rational approach to future therapeutic strategies for manipulating complement with the goal of mitigating adverse pregnancy outcomes, preserving host defense, and improving long term outcomes for both mother and child. PMID:25802092

  19. Interaction of Human Complement with Sbi, a Staphylococcal Immunoglobulin-binding Protein

    PubMed Central

    Burman, Julia D.; Leung, Elisa; Atkins, Karen L.; O’Seaghdha, Maghnus N.; Lango, Lea; Bernadó, Pau; Bagby, Stefan; Svergun, Dmitri I.; Foster, Timothy J.; Isenman, David E.; van den Elsen, Jean M. H.

    2009-01-01

    Staphylococcal immunoglobulin-binding protein, Sbi, is a 436-residue protein produced by many strains of Staphylococcus aureus. It was previously characterized as being cell surface-associated and having binding capacity for human IgG and β2-glycoprotein I. Here we show using small angle x-ray scattering that the proposed extracellular region of Sbi (Sbi-E) is an elongated molecule consisting of four globular domains, two immunoglobulin-binding domains (I and II) and two novel domains (III and IV). We further show that together domains III and IV (Sbi-III-IV), as well as domain IV on its own (Sbi-IV), bind complement component C3 via contacts involving both the C3dg fragment and the C3a anaphylatoxin domain. Preincubation of human serum with either Sbi-E or Sbi-III-IV is inhibitory to all complement pathways, whereas domain IV specifically inhibits the alternative pathway. Monitoring C3 activation in serum incubated with Sbi fragments reveals that Sbi-E and Sbi-III-IV both activate the alternative pathway, leading to consumption of C3. By contrast, inhibition of this pathway by Sbi-IV does not involve C3 consumption. The observation that Sbi-E activates the alternative pathway is counterintuitive to intact Sbi being cell wall-associated, as recruiting complement to the surface of S. aureus would be deleterious to the bacterium. Upon re-examination of this issue, we found that Sbi was not associated with the cell wall fraction, but rather was found in the growth medium, consistent with it being an excreted protein. As such, our data suggest that Sbi helps mediate bacterial evasion of complement via a novel mechanism, namely futile fluid-phase consumption. PMID:18434316

  20. C5a anaphylatoxin as a product of complement activation up-regulates the complement inhibitory factor H in rat Kupffer cells.

    PubMed

    Schlaf, Gerald; Nitzki, Frauke; Heine, Ines; Hardeland, Rüdiger; Schieferdecker, Henrike L; Götze, Otto

    2004-11-01

    The 155-kDa complement regulator factor H (FH) is the predominant soluble regulatory protein of the complement system. It acts as a cofactor for the factor I-mediated conversion of the component C3b to iC3b, competes with factor B for a binding site on C3b and C3(H2O) and promotes the dissociation of the C3bBb complex. The primary site of synthesis is the liver, i.e. FH-specific mRNA and protein were identified in both hepatocytes (HC) and Kupffer cells (KC). Previous studies in rat primary HC and KC had shown that the proinflammatory cytokine IFN-gamma influences the balance between activation and inhibition of the complement system through up-regulation of the inhibitory FH. In this study we show that C5a, as a product of complement activation, stimulates the expression of FH-specific mRNA and protein in KC and thus induces a negative feedback. Quantitative-competitive RT-PCR showed an approximate threefold C5a-induced up-regulation of FH. ELISA analyses revealed a corresponding increase in FH protein in the supernatants of KC. The up-regulation of FH was completely inhibited by the C5a-blocking monoclonal antibody 6-9F. Furthermore, an involvement of LPS and IFN-gamma was excluded, which strongly indicates a direct effect of C5a on the expression of FH in KC. PMID:15376195

  1. Clinical hypothermia temperatures increase complement activation and cell destruction via the classical pathway

    PubMed Central

    2014-01-01

    Background Therapeutic hypothermia is a treatment modality that is increasingly used to improve clinical neurological outcomes for ischemia-reperfusion injury-mediated diseases. Antibody-initiated classical complement pathway activation has been shown to contribute to ischemia-reperfusion injury in multiple disease processes. However, how therapeutic hypothermia affects complement activation is unknown. Our goal was to measure the independent effect of temperature on complement activation, and more specifically, examine the relationship between clinical hypothermia temperatures (31–33°C), and complement activation. Methods Antibody-sensitized erythrocytes were used to assay complement activation at temperatures ranging from 0-41°C. Individual complement pathway components were assayed by ELISA, Western blot, and quantitative dot blot. Peptide Inhibitor of complement C1 (PIC1) was used to specifically inhibit activation of C1. Results Antibody-initiated complement activation resulting in eukaryotic cell lysis was increased by 2-fold at 31°C compared with 37°C. Antibody-initiated complement activation in human serum increased as temperature decreased from 37°C until dramatically decreasing at 13°C. Quantitation of individual complement components showed significantly increased activation of C4, C3, and C5 at clinical hypothermia temperatures. In contrast, C1s activation by heat-aggregated IgG decreased at therapeutic hypothermia temperatures consistent with decreased enzymatic activity at lower temperatures. However, C1q binding to antibody-coated erythrocytes increased at lower temperatures, suggesting that increased classical complement pathway activation is mediated by increased C1 binding at therapeutic hypothermia temperatures. PIC1 inhibited hypothermia-enhanced complement-mediated cell lysis at 31°C by up to 60% (P = 0.001) in a dose dependent manner. Conclusions In summary, therapeutic hypothermia temperatures increased antibody

  2. Genetic susceptibility to chronic wasting disease in free-ranging white-tailed deer: complement component C1q and Prnp polymorphisms

    USGS Publications Warehouse

    Blanchong, Julie A.; Heisey, Dennis M.; Scribner, Kim T.; Libants, Scot V.; Johnson, Chad; Aiken, Judd M.; Langenberg, Julia A.; Samuel, Michael D.

    2009-01-01

    The genetic basis of susceptibility to chronic wasting disease (CWD) in free-ranging cervids is of great interest. Association studies of disease susceptibility in free-ranging populations, however, face considerable challenges including: the need for large sample sizes when disease is rare, animals of unknown pedigree create a risk of spurious results due to population admixture, and the inability to control disease exposure or dose. We used an innovative matched case–control design and conditional logistic regression to evaluate associations between polymorphisms of complement C1q and prion protein (Prnp) genes and CWD infection in white-tailed deer from the CWD endemic area in south-central Wisconsin. To reduce problems due to admixture or disease-risk confounding, we used neutral genetic (microsatellite) data to identify closely related CWD-positive (n = 68) and CWD-negative (n = 91) female deer to serve as matched cases and controls. Cases and controls were also matched on factors (sex, location, age) previously demonstrated to affect CWD infection risk. For Prnp, deer with at least one Serine (S) at amino acid 96 were significantly less likely to be CWD-positive relative to deer homozygous for Glycine (G). This is the first characterization of genes associated with the complement system in white-tailed deer. No tests for association between any C1q polymorphism and CWD infection were significant at p < 0.05. After controlling for Prnp, we found weak support for an elevated risk of CWD infection in deer with at least one Glycine (G) at amino acid 56 of the C1qC gene. While we documented numerous amino acid polymorphisms in C1q genes none appear to be strongly associated with CWD susceptibility.

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

    PubMed

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

    2014-10-01

    Complement convertases are enzymatic complexes that play a central role in sustaining and amplification of the complement cascade. Impairment of complement function leads directly or indirectly to pathological conditions, including higher infection rate, kidney diseases, autoimmune- or neurodegenerative diseases and ischaemia-reperfusion injury. An assay for direct measurement of activity of the convertases in patient sera is not available. Existing assays testing convertase function are based on purified complement components and, thus, convertase formation occurs under non-physiological conditions. We designed a new assay, in which C5 blocking compounds enabled separation of the complement cascade into two phases: the first ending at the stage of C5 convertases and the second ending with membrane attack complex formation. The use of rabbit erythrocytes or antibody-sensitized sheep erythrocytes as the platforms for convertase formation enabled easy readout based on measurement of haemolysis. Thus, properties of patient sera could be studied directly regarding convertase activity and membrane attack complex formation. Another advantage of this assay was the possibility to screen for host factors such as C3 nephritic factor and other anti-complement autoantibodies, or gain-of-function mutations, which prolong the half-life of complement convertases. Herein, we present proof of concept, detailed description and validation of this novel assay. PMID:24853370

  4. C3d adjuvant effects are mediated through the activation of C3d-specific autoreactive T cells

    PubMed Central

    De Groot, Anne S.; Ross, Ted M.; Levitz, Lauren; Messitt, Timothy J.; Tassone, Ryan; Boyle, Christine M.; Vincelli, Amber J.; Moise, Leonard; Martin, William; Knopf, Paul M.

    2014-01-01

    Complement fragment C3d covalently attached to antigens enhances immune responses, particularly for antigens lacking T cell epitopes. Enhancement has been attributed to receptor cross-linking between complement receptor CR2 (CD21) and polysaccharide antigen to surface IgM on naïve B cells. Paradoxically, C3d has still been shown to increase immune responses in CD21 KO mice, suggesting that an auxiliary activation pathway exists. In prior studies, we demonstrated the CD21-independent C3d adjuvant effect might be due to T cell recognition of C3d T helper epitopes processed and presented by MHC class II on the B cell surface. C3d peptide sequences containing concentrated clusters of putative human C3 T cell epitopes were identified using the epitope-mapping algorithm, EpiMatrix. These peptide sequences were synthesized and shown in vitro to bind multiple HLA-DR alleles with high affinity, and induce IFNγ responses in healthy donor PBMCs. In the present studies, we establish further correlations between HLA binding and HLA-specific lymphocyte reactions with select epitope clusters. Additionally, we show that the T cell phenotype of C3d-specific reactive T cells is CD4+CD45RO+ memory T cells. Finally, mutation of a single T cell epitope residing within the P28 peptide segment of C3d resulted in significantly diminished adjuvant activity in BALB/c mice. Collectively, these studies support the hypothesis that the paradoxical enhancement of immune responses by C3d in the absence of CD21 is due to internalization and processing of C3d into peptides that activate autoreactive CD4+ T helper cells in the context of HLA class II. PMID:25385064

  5. Strategies developed by bacteria and virus for protection from the human complement system.

    PubMed

    Blom, A M

    2004-01-01

    The complement system is an important part of innate immunity providing immediate protection against pathogens without a need for previous exposure. Its importance is clearly shown by the fact that patients lacking complement components suffer from fulminant and recurring infections. Complement is an explosive cascade, and in order to control it there are inhibitors present on every human cell and also circulating in blood. However, many infectious agents have developed strategies to prevent clearance and destruction by complement. Some pathogens simply hijack the host's complement inhibitors, while others are able to produce their own homologues of human inhibitors. Knowledge of these mechanisms on a molecular level may aid development of vaccines and novel therapeutic strategies that would be more specific than the use of antibiotics that, apart from causing resistance problems, also affect the normal flora, the outcome of which could be devastating. In this study the structural requirements and functional consequences of interactions between the major soluble inhibitor of complement C4b-binding protein and Neisseria gonorrhoeae, Bordetella pertussis, Streptococcus pyogenes, Escherichia coli K1, Moraxella catarrhalis and Candida albicans are described. Furthermore, a novel inhibitor produced by Kaposi's sarcoma-associated herpesvirus is identified and characterized in detail: KCP. It is shown that KCP inhibits classical C3-convertase and presents activated complement factors C4b and C3b for destruction by a serine proteinase, factor I. Using molecular modelling and site-directed mutagenesis, it was possible to localize sites on the surface of KCP required for complement inhibition and it is concluded that KCP uses molecular mechanisms identical to human inhibitors. PMID:15276914

  6. The Lectin Pathway of Complement and Rheumatic Heart Disease

    PubMed Central

    Beltrame, Marcia Holsbach; Catarino, Sandra Jeremias; Goeldner, Isabela; Boldt, Angelica Beate Winter; de Messias-Reason, Iara José

    2014-01-01

    The innate immune system is the first line of host defense against infection and is comprised of humoral and cellular mechanisms that recognize potential pathogens within minutes or hours of entry. The effector components of innate immunity include epithelial barriers, phagocytes, and natural killer cells, as well as cytokines and the complement system. Complement plays an important role in the immediate response against microorganisms, including Streptococcus sp. The lectin pathway is one of three pathways by which the complement system can be activated. This pathway is initiated by the binding of mannose-binding lectin (MBL), collectin 11 (CL-K1), and ficolins (Ficolin-1, Ficolin-2, and Ficolin-3) to microbial surface oligosaccharides and acetylated residues, respectively. Upon binding to target molecules, MBL, CL-K1, and ficolins form complexes with MBL-associated serine proteases 1 and 2 (MASP-1 and MASP-2), which cleave C4 and C2 forming the C3 convertase (C4b2a). Subsequent activation of complement cascade leads to opsonization, phagocytosis, and lysis of target microorganisms through the formation of the membrane-attack complex. In addition, activation of complement may induce several inflammatory effects, such as expression of adhesion molecules, chemotaxis and activation of leukocytes, release of reactive oxygen species, and secretion of cytokines and chemokines. In this chapter, we review the general aspects of the structure, function, and genetic polymorphism of lectin-pathway components and discuss most recent understanding on the role of the lectin pathway in the predisposition and clinical progression of Rheumatic Fever. PMID:25654073

  7. Complement System Part II: Role in Immunity

    PubMed Central

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

    2015-01-01

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

  8. Unbiased expression mapping identifies a link between the complement and cholinergic systems in the rat central nervous system.

    PubMed

    Lindblom, Rickard P F; Ström, Mikael; Heinig, Matthias; Al Nimer, Faiez; Aeinehband, Shahin; Berg, Alexander; Dominguez, Cecilia A; Vijayaraghavan, Swetha; Zhang, Xing-Mei; Harnesk, Karin; Zelano, Johan; Hübner, Norbert; Cullheim, Staffan; Darreh-Shori, Taher; Diez, Margarita; Piehl, Fredrik

    2014-02-01

    The complement system is activated in a wide spectrum of CNS diseases and is suggested to play a role in degenerative phenomena such as elimination of synaptic terminals. Still, little is known of mechanisms regulating complement activation in the CNS. Loss of synaptic terminals in the spinal cord after an experimental nerve injury is increased in the inbred DA strain compared with the PVG strain and is associated with expression of the upstream complement components C1q and C3, in the absence of membrane attack complex activation and neutrophil infiltration. To further dissect pathways regulating complement expression, we performed genome-wide expression profiling and linkage analysis in a large F2(DA × PVG) intercross, which identified quantitative trait loci regulating expression of C1qa, C1qb, C3, and C9. Unlike C1qa, C1qb, and C9, which all displayed distinct coregulation with different cis-regulated C-type lectins, C3 was regulated in a coexpression network immediately downstream of butyrylcholinesterase. Butyrylcholinesterase hydrolyses acetylcholine, which exerts immunoregulatory effects partly through TNF-α pathways. Accordingly, increased C3, but not C1q, expression was demonstrated in rat and mouse glia following TNF-α stimulation, which was abrogated in a dose-dependent manner by acetylcholine. These findings demonstrate new pathways regulating CNS complement expression using unbiased mapping in an experimental in vivo system. A direct link between cholinergic activity and complement activation is supported by in vitro experiments. The identification of distinct pathways subjected to regulation by naturally occurring genetic variability is of relevance for the understanding of disease mechanisms in neurologic conditions characterized by neuronal injury and complement activation. PMID:24353269

  9. Complement and the severity of pulmonary failure.

    PubMed

    Weigelt, J A; Chenoweth, D E; Borman, K R; Norcross, J F

    1988-07-01

    Complement-induced granulocyte aggregation is suspected as a cause of the adult respiratory distress syndrome. Quantifying the lung damage in these patients is difficult, and complement levels combined with clinical parameters of oxygenation might help define the severity of pulmonary deterioration. Forty-five high-risk patients, selected by arterial blood gas criteria, had their pulmonary insult related to C3a and C5a levels. Patients were stratified by pulmonary shunt, alveolar-arterial oxygen gradient, and radiographic findings into two categories of severity: pulmonary dysfunction, a milder insult, and ARDS, a major aberration in pulmonary function. The clinical assignment of a diagnostic category required at least 96 hours of monitoring. During this 96-hour period, multiple complement levels were obtained. These complement levels were then compared in pulmonary dysfunction and ARDS patients. ARDS patients had significantly higher C3a and C5a values after the patients were selected as high risk. These results suggest that the amount of complement activated in patients with incipient respiratory failure correlates with the severity of eventual pulmonary insult. The use of arterial blood gases and C3a and C5a levels should allow better and earlier definition of patients at risk for ARDS. PMID:3260964

  10. Linkage Specificity and Role of Properdin in Activation of the Alternative Complement Pathway by Fungal Glycans

    PubMed Central

    Agarwal, Sarika; Specht, Charles A.; Huang, Haibin; Ostroff, Gary R.; Ram, Sanjay; Rice, Peter A.; Levitz, Stuart M.

    2011-01-01

    ABSTRACT Fungal cell walls are predominantly composed of glucans, mannans, and chitin. Recognition of these glycans by the innate immune system is a critical component of host defenses against the mycoses. Complement, an important arm of innate immunity, plays a significant role in fungal pathogenesis, especially the alternative pathway (AP). Here we determine that the glycan monosaccharide composition and glycosidic linkages affect AP activation and C3 deposition. Furthermore, properdin, a positive regulator of the AP, contributes to these functions. AP activation by glycan particles that varied in composition and linkage was measured by C3a generation in serum treated with 10 mM EGTA and 10 mM Mg2+ (Mg-EGTA-treated serum) (AP specific; properdin functional) or Mg-EGTA-treated serum that lacked functional properdin. Particles that contained either β1→3 or β1→6 glucans or both generated large and similar amounts of C3a when the AP was intact. Blocking properdin function resulted in 5- to 10-fold-less C3a production by particulate β1→3 glucans. However, particulate β1→6 glucans generated C3a via the AP only in the presence of intact properdin. Interestingly, zymosan and glucan-mannan particles (GMP), which contain both β-glucans and mannans, also required properdin to generate C3a. The β1→4 glycans chitin and chitosan minimally activated C3 even when properdin was functional. Finally, properdin binding to glucan particles (GP) and zymosan in serum required active C3. Properdin colocalized with bound C3, suggesting that in the presence of serum, properdin bound indirectly to glycans through C3 convertases. These findings provide a better understanding of how properdin facilitates AP activation by fungi through interaction with the cell wall components. PMID:21878570

  11. Tissue C3b receptors.

    PubMed Central

    Schrieber, L; Penny, R

    1979-01-01

    Using fluorescein-labelled S. typhi coated with C3b (FBC) the presence of a receptor for C3b in normal human glomeruli has been confirmed. A quantitative system, counting the number of FBC bound per unit area of glomerulus, has been developed. Experimental variables have been studied to determine optimal conditions for FBC binding. Glomerular FBC binding has been shown to be dependent on FBC concentration, temperature and time of tissue incubation. A standardized procedure has been adopted. Using this technique we have examined a number of target tissues, including synovium, skin, lung, choroid plexus and uveal tract, which are frequently affected in systemic immune complex diseases. No evidence of this receptor has been found in these tissues. These results suggest a mechanism different from the C3b receptor operating to localise immune complexes in these non-renal sites. Images FIG. 2 PMID:527266

  12. The cytolytic C5b-9 complement complex: feedback inhibition of complement activation.

    PubMed Central

    Bhakdi, S; Maillet, F; Muhly, M; Kazatchkine, M D

    1988-01-01

    We describe a regulatory function of the terminal cytolytic C5b-9 complex [C5b-9(m)] of human complement. Purified C5b-9(m) complexes isolated from target membranes, whether in solution or bound to liposomes, inhibited lysis of sensitized sheep erythrocytes by whole human serum in a dose-dependent manner. C9 was not required for the inhibitory function since C5b-7 and C5b-8 complexes isolated from membranes were also effective. No effect was found with the cytolytically inactive, fluid-phase SC5b-9 complex. However, tryptic modification of SC5b-9 conferred an inhibitory capacity to the complex, due probably to partial removal of the S protein. Experiments using purified components demonstrated that C5b-9(m) exerts a regulatory effect on the formation of the classical- and alternative-pathway C3 convertases and on the utilization of C5 by cell-bound C5 convertases. C5b-9(m) complexes were unable to inhibit the lysis of cells bearing C5b-7(m) by C8 and C9. Addition of C5b-9(m) to whole human serum abolished its bactericidal effect on the serum-sensitive Escherichia coli K-12 strain W 3110 and suppressed its hemolytic function on antibody-sensitized, autologous erythrocytes. Feedback inhibition by C5b-9(m) represents a biologically relevant mechanism through which complement may autoregulate its effector functions. Images PMID:3162317

  13. Identification of an additional class of C3-binding membrane proteins of human peripheral blood leukocytes and cell lines.

    PubMed Central

    Cole, J L; Housley, G A; Dykman, T R; MacDermott, R P; Atkinson, J P

    1985-01-01

    Proteins binding the third component of complement (C3) were isolated by affinity chromatography from surface-labeled solubilized membranes of human peripheral blood cells and cell lines. The isolated molecules were subjected to NaDodSO4/PAGE, and autoradiographs of these gels indicated that C3-binding proteins could be divided into three groups based on Mr: (i) gp200, an approximately 200,000 Mr molecule previously identified as the C3b/C4b receptor or CR1; (ii) gp140, an approximately 140,000 Mr molecule previously identified as the C3d receptor or CR2; and (iii) gp45-70, a heretofore unrecognized group of 45,000-70,000 Mr C3-binding molecules. The cell distribution, Mr, antigenic cross-reactivity, and specificity of gp45-70 were examined. Erythrocytes have no detectable gp45-70, but all leukocyte populations examined possess this group of molecules. On neutrophils and mononuclear phagocytes, CR1 is the predominant C3-binding glycoprotein, but gp45-70 is present on both cell populations and on macrophage and neutrophil cell lines. B plus null cells, chronic lymphocytic leukemia cells, and an Epstein-Barr virus-transformed B-cell line possess CR1, CR2, and gp45-70. On T cells and T-cell lines gp45-70 is the predominant or, in some cases, the only C3-binding protein isolated. gp45-70 is structurally characterized as a broad band or doublet with a mean Mr that is slightly different for each cell population. gp45-70 binds iC3, C3b, and C4b, but not C3d, indicating that the binding region is probably within the C3c portion of C3b. A polyclonal antibody to CR1 and monoclonal antibodies to CR1 and CR2 do not immunoprecipitate gp45-70. While gp45-70 has not been previously characterized on human cells, a C3b-binding glycoprotein of similar Mr is present on rabbit alveolar macrophages. We conclude that gp45-70 is an additional group of membrane proteins present on human leukocytes that possess ligand-binding activity for C3b. Images PMID:3871945

  14. Identification of an additional class of C3-binding membrane proteins of human peripheral blood leukocytes and cell lines.

    PubMed

    Cole, J L; Housley, G A; Dykman, T R; MacDermott, R P; Atkinson, J P

    1985-02-01

    Proteins binding the third component of complement (C3) were isolated by affinity chromatography from surface-labeled solubilized membranes of human peripheral blood cells and cell lines. The isolated molecules were subjected to NaDodSO4/PAGE, and autoradiographs of these gels indicated that C3-binding proteins could be divided into three groups based on Mr: (i) gp200, an approximately 200,000 Mr molecule previously identified as the C3b/C4b receptor or CR1; (ii) gp140, an approximately 140,000 Mr molecule previously identified as the C3d receptor or CR2; and (iii) gp45-70, a heretofore unrecognized group of 45,000-70,000 Mr C3-binding molecules. The cell distribution, Mr, antigenic cross-reactivity, and specificity of gp45-70 were examined. Erythrocytes have no detectable gp45-70, but all leukocyte populations examined possess this group of molecules. On neutrophils and mononuclear phagocytes, CR1 is the predominant C3-binding glycoprotein, but gp45-70 is present on both cell populations and on macrophage and neutrophil cell lines. B plus null cells, chronic lymphocytic leukemia cells, and an Epstein-Barr virus-transformed B-cell line possess CR1, CR2, and gp45-70. On T cells and T-cell lines gp45-70 is the predominant or, in some cases, the only C3-binding protein isolated. gp45-70 is structurally characterized as a broad band or doublet with a mean Mr that is slightly different for each cell population. gp45-70 binds iC3, C3b, and C4b, but not C3d, indicating that the binding region is probably within the C3c portion of C3b. A polyclonal antibody to CR1 and monoclonal antibodies to CR1 and CR2 do not immunoprecipitate gp45-70. While gp45-70 has not been previously characterized on human cells, a C3b-binding glycoprotein of similar Mr is present on rabbit alveolar macrophages. We conclude that gp45-70 is an additional group of membrane proteins present on human leukocytes that possess ligand-binding activity for C3b. PMID:3871945

  15. An Inhibitor of the Alternative Pathway of Complement in Saliva of New World Anopheline Mosquitoes.

    PubMed

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

    2016-07-15

    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

  16. Protection of gingival epithelium against complement-mediated damage by strong expression of the membrane attack complex inhibitor protectin (CD59).

    PubMed

    Rautemaa, R; Meri, S

    1996-01-01

    Adult periodontitis (AP) is a chronic inflammatory disease of the tooth-supporting apparatus. Activation products of the inflammation-inducing complement system have been detected in the gingival crevicular fluid at the site of gingival inflammation. In the present study, we examined whether evidence for ongoing complement activation in gingival tissues of patients with AP can be obtained. In light of the potential tissue-damaging effects of the complement system, we also examined how the gingival tissue is protected against the cytolytic activity of complement. Surgical and autopsy samples of AP (n = 18) and healthy (n = 11) gingiva were analyzed for the expression or deposition of the complement regulators protectin (CD59) and vitronectin (S-protein) and complement components C3d and C9 by indirect immunofluorescence microscopy with specific antibodies. In healthy gingiva, protection was strongly expressed on the membranes of epithelial cells and on the vascular endothelia of the underlying connective tissue. In AP, protectin was also strongly expressed by endothelial cells, but in the epithelia the expression was granular and weaker than in the healthy gingiva. Coarse granular deposits of complement components were seen in the subepithelial tissues of 61% (C3d), 39% (C9), and 33% (vitronectin) of AP patients, compared with 9% (one case in 11) in healthy controls. In addition, deposits of C3d, C9, and vitronectin were observed on the basement membranes of both pocket and oral epithelium of healthy and AP gingiva but not at sites of protectin expression. The results suggest an increased turnover of the complement system in the gingival tissues of AP patients. The gingival epithelium and connective tissue endothelia are well-protected against damage by the membrane attack complex of complement (MAC). Protection of the underlying connective tissue is insufficient, however, and may allow for deposition of MAC and autologous tissue damage in AP. PMID:8655761

  17. A recombinant two-module form of human properdin is an inhibitor of the complement alternative pathway.

    PubMed

    Kouser, Lubna; Abdul-Aziz, Munirah; Tsolaki, Anthony G; Singhal, Dipti; Schwaeble, Wilhelm J; Urban, Britta C; Khan, Haseeb A; Sim, Robert B; Kishore, Uday

    2016-05-01

    Properdin upregulates the alternative complement pathway by binding and stabilising the C3 convertase complex (C3bBb). Properdin is a soluble glycoprotein and its flexible rod-like 53kDa monomers form cyclic polymers (dimers, trimers, tetramers and pentamers). The properdin monomer consists of seven thrombospondin type I repeats (TSR 0-6), which are similar and homologous to domains found in circumsporozoite and thrombospondin-related anonymous proteins of Plasmodium species, ETP100 of Eimeria tenella, various complement components C6-C9, and thrombospondin I and II. Using deletion constructs, TSR4 and TSR5 of human properdin were implicated in C3b binding and stabilising C3 convertase. However, individually expressed TSR4 or TSR5 failed to bind properdin ligands. Here, we have expressed and characterized biologically active TSR4 and TSR5 together (TSR4+5) in tandem in Escherichia coli, fused to maltose-binding protein. MBP-TSR4+5 bind solid-phase C3b, sulfatides and glycosaminoglycans. In addition, functionally active recombinant TSR4+5 modules inhibit the alternative pathway of complement. PMID:27060503

  18. Complement activation promotes colitis-associated carcinogenesis through activating intestinal IL-1β/IL-17A axis.

    PubMed

    Ning, C; Li, Y-Y; Wang, Y; Han, G-C; Wang, R-X; Xiao, H; Li, X-Y; Hou, C-M; Ma, Y-F; Sheng, D-S; Shen, B-F; Feng, J-N; Guo, R-F; Li, Y; Chen, G-J

    2015-11-01

    Colitis-associated colorectal cancer (CAC) is the most serious complication of inflammatory bowel disease (IBD). Excessive complement activation has been shown to be involved in the pathogenesis of IBD. However, its role in the development of CAC is largely unknown. Here, using a CAC model induced by combined administration of azoxymethane (AOM) and dextran sulfate sodium (DSS), we demonstrated that complement activation was required for CAC pathogenesis. Deficiency in key components of complement (e.g., C3, C5, or C5a receptor) rendered tumor repression in mice subjected to AOM/DSS. Mechanistic investigation revealed that complement ablation dramatically reduced proinflammatory cytokine interleukin (IL)-1β levels in the colonic tissues that was mainly produced by infiltrating neutrophils. IL-1β promoted colon carcinogenesis by eliciting IL-17 response in intestinal myeloid cells. Furthermore, complement-activation product C5a represented a potent inducer for IL-1β in neutrophil, accounting for downregulation of IL-1β levels in the employed complement-deficient mice. Overall, our study proposes a protumorigenic role of complement in inflammation-related colorectal cancer and that the therapeutic strategies targeting complement may be beneficial for the treatment of CAC in clinic. PMID:25736459

  19. Complement analysis 2016: Clinical indications, laboratory diagnostics and quality control.

    PubMed

    Prohászka, Zoltán; Nilsson, Bo; Frazer-Abel, Ashley; Kirschfink, Michael

    2016-11-01

    In recent years, complement analysis of body fluids and biopsies, going far beyond C3 and C4, has significantly enhanced our understanding of the disease process. Such expanded complement analysis allows for a more precise differential diagnosis and for critical monitoring of complement-targeted therapy. These changes are a result of the growing understanding of the involvement of complement in a diverse set of disorders. To appreciate the importance of proper complement analysis, it is important to understand the role it plays in disease. Historically, it was the absence of complement as manifested in severe infection that was noted. Since then complement has been connected to a variety of inflammatory disorders, such as autoimmune diseases and hereditary angioedema. While the role of complement in the rejection of renal grafts has been known longer, the significant impact of complement. In certain nephropathies has now led to the reclassification of some rare kidney diseases and an increased role for complement analysis in diagnosis. Even more unexpected is that complement has also been implicated in neural, ophtalmological and dermatological disorders. With this level of involvement in some varied and impactful health issues proper complement testing is clearly important; however, analysis of the complement system varies widely among laboratories. Except for a few proteins, such as C3 and C4, there are neither well-characterized standard preparations nor calibrated assays available. This is especially true for the inter-laboratory variation of tests which assess classical, alternative, or lectin pathway function. In addition, there is a need for the standardization of the measurement of complement activation products that are so critical in determining whether clinically relevant complement activation has occurred in vivo. Finally, autoantibodies to complement proteins (e.g. anti-C1q), C3 and C4 convertases (C3 and C4 nephritic factor) or to regulatory proteins

  20. Complement-activating ability of leucocytes from patients with complement factor I deficiency.

    PubMed Central

    Marquart, H V; Rasmussen, J M; Leslie, R G

    1997-01-01

    Previous studies from this laboratory have shown that normal peripheral blood B cells are capable of activating complement via the alternative pathway (AP), that the activation is associated with complement receptor type 2 (CR2) expression, and that erythrocytes at normal blood levels partially inhibit the activation. The purpose of the present study was to investigate whether factor I (FI) deficiency, which leads to continued formation of the AP convertase (C3bBb) resulting in the consumption of factor B and C3 and large scale generation of C3b fragments, affects the phenotype and/or function of the patients' B cells. Using flow cytometry, peripheral blood leucocytes (PBL) from two FI-deficient patients were investigated for expression of complement receptors and complement regulatory proteins, in vivo-deposited C3 fragments and in vitro complement-activating ability. CR1 levels on B cells were significantly lower in FI-deficient patients than in normal individuals, whereas CR2 levels were found to be reduced, although not to a significant extent. CR1 levels on monocytes and polymorphonuclear leucocytes (PMN) were found to be normal or slightly raised. All leucocyte subpopulations were found to be covered in vivo with C3b fragments. AP activation on B cells from FI-deficient patients in homologous serum was significantly reduced compared with that for normal individuals, whereas no in vitro activation was seen in autologous serum. In addition, the in vivo-bound C3b fragments were degraded to C3d,g when the patients' PBL were incubated in homologous serum containing EDTA. Finally, the patients, erythrocytes failed to exert any inhibition on AP activation in homologous serum. PMID:9301541

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

    PubMed

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

    2016-06-01

    Mycobacterium leprae infection gives rise to the immunologically and histopathologically classified spectrum of leprosy. At present, several tools for the stratification of patients are based on acquired immunity markers. However, the role of innate immunity, particularly the complement system, is largely unexplored. The present retrospective study was undertaken to explore whether the systemic levels of complement activation components and regulators can stratify leprosy patients, particularly in reference to the reactional state of the disease. Serum samples from two cohorts were analysed. The cohort from Bangladesh included multi-bacillary (MB) patients with (n = 12) or without (n = 46) reaction (R) at intake and endemic controls (n = 20). The cohort from Ethiopia included pauci-bacillary (PB) (n = 7) and MB (n = 23) patients without reaction and MB (n = 15) patients with reaction. The results showed that the activation products terminal complement complex (TCC) (P ≤ 0·01), C4d (P ≤ 0·05) and iC3b (P ≤ 0·05) were specifically elevated in Bangladeshi patients with reaction at intake compared to endemic controls. In addition, levels of the regulator clusterin (P ≤ 0·001 without R; P < 0·05 with R) were also elevated in MB patients, irrespective of a reaction. Similar analysis of the Ethiopian cohort confirmed that, irrespective of a reaction, serum TCC levels were increased significantly in patients with reactions compared to patients without reactions (P ≤ 0·05). Our findings suggests that serum TCC levels may prove to be a valuable tool in diagnosing patients at risk of developing reactions. PMID:26749503

  2. Targeting mechanisms at sites of complement activation for imaging and therapy.

    PubMed

    Holers, V Michael

    2016-06-01

    The complement system plays a key role in many acute injury states as well as chronic autoimmune and inflammatory diseases. Localized complement activation and alternative pathway-mediated amplification on diverse target surfaces promote local recruitment of pro-inflammatory cells and elaboration of other mediators. Despite a general understanding of the architecture of the system, though, many of the mechanisms that underlie site-specific complement activation and amplification in vivo are incompletely understood. In addition, there is no capability yet to measure the level of local tissue site-specific complement activation in patients without performing biopsies to detect products using immunohistochemical techniques. Herein is reviewed emerging evidence obtained through clinical research studies of human rheumatoid arthritis along with translational studies of its disease models which demonstrate that several parallel mechanisms are involved in site-specific amplification of activation of the complement system in vivo. Among these processes are de-regulation of the alternative pathway, effector pathway-catalyzed amplification of proximal complement activation, recognition of injury-associated ligands by components of the lectin pathway, and engagement of pathogenic natural antibodies that recognize a limited set of injury-associated neoepitopes. Studies suggest that each of these inter-related processes can play key roles in amplification of complement-dependent injury on self-tissues in vivo. These findings, in addition to development of an imaging strategy described herein designed to quantitatively measure local complement C3 fixation, have relevance to therapeutic and diagnostic strategies targeting the complement system. PMID:25979851

  3. Role of Complement Activation in Obliterative Bronchiolitis Post Lung Transplantation

    PubMed Central

    Suzuki, Hidemi; Lasbury, Mark E.; Fan, Lin; Vittal, Ragini; Mickler, Elizabeth A.; Benson, Heather L.; Shilling, Rebecca; Wu, Qiang; Weber, Daniel J.; Wagner, Sarah R.; Lasaro, Melissa; Devore, Denise; Wang, Yi; Sandusky, George E.; Lipking, Kelsey; Pandya, Pankita; Reynolds, John; Love, Robert; Wozniak, Thomas; Gu, Hongmei; Brown, Krista M.; Wilkes, David S.

    2013-01-01

    Obliterative bronchiolitis (OB) post lung transplantation involves IL-17 regulated autoimmunity to type V collagen and alloimmunity, which could be enhanced by complement activation. However, the specific role of complement activation in lung allograft pathology, IL-17 production, and OB are unknown. The current study examines the role of complement activation in OB. Complement regulatory protein (CRP) (CD55, CD46, Crry/CD46) expression was down regulated in human and murine OB; and C3a, a marker of complement activation, was up regulated locally. IL-17 differentially suppressed Crry expression in airway epithelial cells in vitro. Neutralizing IL-17 recovered CRP expression in murine lung allografts and decreased local C3a production. Exogenous C3a enhanced IL-17 production from alloantigen or autoantigen (type V collagen) reactive lymphocytes. Systemically neutralizing C5 abrogated the development of OB, reduced acute rejection severity, lowered systemic and local levels of C3a and C5a, recovered CRP expression, and diminished systemic IL-17 and IL-6 levels. These data indicated that OB induction is in part complement dependent due to IL-17 mediated down regulation of CRPs on airway epithelium. C3a and IL-17 are part of a feed forward loop that may enhance CRP down regulation, suggesting that complement blockade could be a therapeutic strategy for OB. PMID:24043901

  4. Hyperglycemia inhibits complement-mediated immunological control of S. aureus in a rat model of peritonitis.

    PubMed

    Mauriello, Clifford T; Hair, Pamela S; Rohn, Reuben D; Rister, Nicholas S; Krishna, Neel K; Cunnion, Kenji M

    2014-01-01

    Hyperglycemia from diabetes is associated with increased risk of infection from S. aureus and increased severity of illness. Previous work in our laboratory demonstrated that elevated glucose (>6 mM) dramatically inhibited S. aureus-initiated complement-mediated immune effectors. Here we report in vivo studies evaluating the extent to which a hyperglycemic environment alters complement-mediated control of S. aureus infection in a rat peritonitis model. Rats were treated with streptozocin to induce diabetes or sham-treated and then inoculated i.p. with S. aureus. Rats were euthanized and had peritoneal lavage at 2 or 24 hours after infection to evaluate early and late complement-mediated effects. Hyperglycemia decreased the influx of IgG and complement components into the peritoneum in response to S. aureus infection and decreased anaphylatoxin generation. Hyperglycemia decreased C4-fragment and C3-fragment opsonization of S. aureus recovered in peritoneal fluids, compared with euglycemic or insulin-rescued rats. Hyperglycemic rats showed decreased phagocytosis efficiency compared with euglycemic rats, which correlated inversely with bacterial survival. These results suggest that hyperglycemia inhibited humoral effector recruitment, anaphylatoxin generation, and complement-mediated opsonization of S. aureus, suggesting that hyperglycemic inhibition of complement effectors may contribute to the increased risk and severity of S. aureus infections in diabetic patients. PMID:25610878

  5. Hyperglycemia Inhibits Complement-Mediated Immunological Control of S. aureus in a Rat Model of Peritonitis

    PubMed Central

    Mauriello, Clifford T.; Hair, Pamela S.; Rohn, Reuben D.; Rister, Nicholas S.; Krishna, Neel K.; Cunnion, Kenji M.

    2014-01-01

    Hyperglycemia from diabetes is associated with increased risk of infection from S. aureus and increased severity of illness. Previous work in our laboratory demonstrated that elevated glucose (>6 mM) dramatically inhibited S. aureus-initiated complement-mediated immune effectors. Here we report in vivo studies evaluating the extent to which a hyperglycemic environment alters complement-mediated control of S. aureus infection in a rat peritonitis model. Rats were treated with streptozocin to induce diabetes or sham-treated and then inoculated i.p. with S. aureus. Rats were euthanized and had peritoneal lavage at 2 or 24 hours after infection to evaluate early and late complement-mediated effects. Hyperglycemia decreased the influx of IgG and complement components into the peritoneum in response to S. aureus infection and decreased anaphylatoxin generation. Hyperglycemia decreased C4-fragment and C3-fragment opsonization of S. aureus recovered in peritoneal fluids, compared with euglycemic or insulin-rescued rats. Hyperglycemic rats showed decreased phagocytosis efficiency compared with euglycemic rats, which correlated inversely with bacterial survival. These results suggest that hyperglycemia inhibited humoral effector recruitment, anaphylatoxin generation, and complement-mediated opsonization of S. aureus, suggesting that hyperglycemic inhibition of complement effectors may contribute to the increased risk and severity of S. aureus infections in diabetic patients. PMID:25610878

  6. Exploitation of the Complement System by Oncogenic Kaposi's Sarcoma-Associated Herpesvirus for Cell Survival and Persistent Infection

    PubMed Central

    Lee, Myung-Shin; Jones, Tiffany; Song, Dae-Yong; Jang, Jae-Hyuk; Jung, Jae U.; Gao, Shou-Jiang

    2014-01-01

    During evolution, herpesviruses have developed numerous, and often very ingenious, strategies to counteract efficient host immunity. Specifically, Kaposi's sarcoma-associated herpesvirus (KSHV) eludes host immunity by undergoing a dormant stage, called latency wherein it expresses a minimal number of viral proteins to evade host immune activation. Here, we show that during latency, KSHV hijacks the complement pathway to promote cell survival. We detected strong deposition of complement membrane attack complex C5b-9 and the complement component C3 activated product C3b on Kaposi's sarcoma spindle tumor cells, and on human endothelial cells latently infected by KSHV, TIME-KSHV and TIVE-LTC, but not on their respective uninfected control cells, TIME and TIVE. We further showed that complement activation in latently KSHV-infected cells was mediated by the alternative complement pathway through down-regulation of cell surface complement regulatory proteins CD55 and CD59. Interestingly, complement activation caused minimal cell death but promoted the survival of latently KSHV-infected cells grown in medium depleted of growth factors. We found that complement activation increased STAT3 tyrosine phosphorylation (Y705) of KSHV-infected cells, which was required for the enhanced cell survival. Furthermore, overexpression of either CD55 or CD59 in latently KSHV-infected cells was sufficient to inhibit complement activation, prevent STAT3 Y705 phosphorylation and abolish the enhanced survival of cells cultured in growth factor-depleted condition. Together, these results demonstrate a novel mechanism by which an oncogenic virus subverts and exploits the host innate immune system to promote viral persistent infection. PMID:25254972

  7. Mitochondria and the Lectin Pathway of Complement*

    PubMed Central

    Brinkmann, Christel R.; Jensen, Lisbeth; Dagnæs-Hansen, Frederik; Holm, Ida E.; Endo, Yuichi; Fujita, Teizo; Thiel, Steffen; Jensenius, Jens C.; Degn, Søren E.

    2013-01-01

    Mitochondria, the powerhouses of our cells, are remnants of a eubacterial endosymbiont. Notwithstanding the evolutionary time that has passed since the initial endosymbiotic event, mitochondria have retained many hallmarks of their eubacterial origin. Recent studies have indicated that during perturbations of normal homeostasis, such as following acute trauma leading to massive necrosis and release of mitochondria, the immune system might mistake symbiont for enemy and initiate an inappropriate immune response. The innate immune system is the first line of defense against invading microbial pathogens, and as such is the primary suspect in the recognition of mitochondria-derived danger-associated molecular patterns and initiation of an aberrant response. Conversely, innate immune mechanisms are also central to noninflammatory clearance of innocuous agents. Here we investigated the role of a central humoral component of innate immunity, the lectin pathway of complement, in recognition of mitochondria in vitro and in vivo. We found that the soluble pattern recognition molecules, mannan-binding lectin (MBL), L-ficolin, and M-ficolin, were able to recognize mitochondria. Furthermore, MBL in complex with MBL-associated serine protease 2 (MASP-2) was able to activate the lectin pathway and deposit C4 onto mitochondria, suggesting that these molecules are involved either in homeostatic clearance of mitochondria or in induction of untoward inflammatory reactions. We found that following mitochondrial challenge, C3 was consumed in vivo in the absence of overt inflammation, indicating a potential role of complement in noninflammatory clearance of mitochondria. Thus, we report here the first indication of involvement of the lectin pathway in mitochondrial immune handling. PMID:23378531

  8. ORF2 protein of porcine circovirus type 2 promotes phagocytic activity of porcine macrophages by inhibiting proteasomal degradation of complement component 1, q subcomponent binding protein (C1QBP) through physical interaction.

    PubMed

    Choi, Chang-Yong; Oh, Hae-Na; Lee, Suk Jun; Chun, Taehoon

    2015-11-01

    Defining how each ORF of porcine circovirus type 2 (PCV2) manipulates the host immune system may be helpful to understand the disease progression of post-weaning multisystemic wasting syndrome. In this study, we demonstrated a direct interaction between the PCV2 ORF2 and complement component 1, q subcomponent binding protein (C1QBP) within the cytoplasm of host macrophages. The physical interaction between PCV2 ORF2 and C1QBP inhibited ubiquitin-mediated proteasomal degradation of C1QBP in macrophages. Increased stability of C1QBP by the interaction with PCV2 ORF2 further enhanced the phagocytic activity of porcine macrophages through the phosphoinositol 3-kinase signalling pathway. This may explain the molecular basis of how PCV2 ORF2 enhances the phagocytic activity of host macrophages. PMID:26361775

  9. Drugs that inhibit complement.

    PubMed

    Schrezenmeier, Hubert; Höchsmann, Britta

    2012-02-01

    The complement system is an important part of the innate immune system. Complement plays a crucial role in the pathophysiology of many disorders. Despite the pivotal role of the complement system, an approved targeted inhibitor of a complement factor became available only recently. Eculizumab is a humanized monoclonal antibody that inhibits complement factor C5. It is a targeted, disease modifying, treatment of paroxysmal nocturnal hemoglobinuria (PNH). It was approved be the US FDA and the European Commission in 2007. In this review we will update the experience with eculizumab in PNH and discuss potential use of eculizumab in other disorders (e.g. cold agglutinin disease; atypical HUS) and new approaches to complement inhibition with drugs other than eculizumab. PMID:22169380

  10. Glycoproteins, antigens, and regulation of complement activation on the surface of the protozoan parasite Trypanosoma lewisi: implications for immune evasion

    SciTech Connect

    Sturtevant, J.E.

    1985-01-01

    The surface antigens and glycoproteins of the rat parasitic protozoan, Trypanosoma lewisi were characterized. Radioiodination with /sup 125/I identified 10 out of more 40 polypeptides separated on sodium dodecyl sulfate polyacrylamide gel electrophoresis. All of these components were identified as glycoproteins by peroxidase-conjugated Conconavalin A (HR-Con A) lectin affinoblotting. This analysis detected that quantitative but not qualitative changes occurred during infection. Localization of most of the reactive determinants was indicated by immunoblotting extracts of radioiodinated T. lewisi. Changes in the antigenicity as related to survival in the host are discussed. The presence of IgG and IgM on the surface of T. lewisi isolated from intact and ..gamma..-irradiated rats (irr.) and that determinants bind Ig from uninfected rat sera (NRS) was indicated by flow cytometric analysis. Immunoblotting identified the major NRS IgG binding component as the 74 kd surface glycoprotein. Complement component C3 deposition during infection was indicated by flow cytometric analysis and immunoblotting. Incubation of intact T. lewisi with normal human sera indicated that C3, C5, and factor B deposition was Mg/sup 2 +/ dependent, Ca/sup 2 +/ independent and deposited C3 was rapidly processed to hemolytically inactive fragments. Radioiodination of intact and protease T. lewisi after cultivation identified three components which correlate with resistance to lysis. This suggests that surface moieties on intact T. lewisi modulate host complement activity by restricting C3/C5 convertase activity.

  11. A study of C3HD in cold interstellar clouds

    NASA Technical Reports Server (NTRS)

    Bell, M. B.; Avery, L. W.; Matthews, H. E.; Feldman, P. A.; Watson, J. K. G.

    1988-01-01

    The 1(10)-1(01) transition of C3HD was detected at 19.418 GHz at twelve positions in cold, dark clouds, and the D hyperfine components were resolved in two sources (L1498 and TMC-1C) well enough to derive values for the D quadrupole coupling constants. Simultaneous observations of C3H2 in each source yield relative integrated line intensities in the range 0.10-0.18, from which relative C3HD/C3H2 abundances in the range 0.05-0.15 were derived. These are among the highest deuteration ratios yet observed. Within the limits of the observational and modeling uncertainties, it is possible to explain the derived C3HD/C3H2 ratios by ion-molecule chemistry if e is equal to about 3 x 10 to the -7th.

  12. Complement and Viral Pathogenesis

    PubMed Central

    Stoermer, Kristina A.; Morrison, Thomas E.

    2011-01-01

    The complement system functions as an immune surveillance system that rapidly responds to infection. Activation of the complement system by specific recognition pathways triggers a protease cascade, generating cleavage products that function to eliminate pathogens, regulate inflammatory responses, and shape adaptive immune responses. However, when dysregulated, these powerful functions can become destructive and the complement system has been implicated as a pathogenic effector in numerous diseases, including infectious diseases. This review highlights recent discoveries that have identified critical roles for the complement system in the pathogenesis of viral infection. PMID:21292294

  13. Glycosylated and Nonglycosylated Complement Control Protein of the Lister Strain of Vaccinia Virus

    PubMed Central

    Kuhn, Jordan; Atukorale, Vajini; Campbell, Joseph; Weir, Jerry P.

    2014-01-01

    The vaccinia virus complement control protein (VCP) is a secreted viral protein that binds the C3b and C4b complement components and inhibits the classic and alternative complement pathways. Previously, we reported that an attenuated smallpox vaccine, LC16m8, which was derived from the Lister strain of vaccinia virus (VV-Lister), expressed a glycosylated form of VCP, whereas published sequence data at that time indicated that the VV-Lister VCP has no motif for N-linked glycosylation. We were interested in determining whether the glycosylation of VCP impairs its biological activity, possibly contributing to the attenuation of LC16m8, and the likely origin of the glycosylated VCP. Expression analysis indicated that VV-Lister contains substrains expressing glycosylated VCP and substrains expressing nonglycosylated VCP. Other strains of smallpox vaccine, as well as laboratory strains of vaccinia virus, all expressed nonglycosylated VCP. Individual Lister virus clones expressing either the glycosylated VCP or the nonglycosylated species were isolated, and partially purified VCP from the isolates were found to be functional equivalents in binding human C3b and C4b complement proteins and inhibiting hemolysis and in immunogenicity. Recombinant vaccinia viruses expressing FLAG-tagged glycosylated VCP (FLAG-VCPg) and nonglycosylated VCP (FLAG-VCP) were constructed based on the Western Reserve strain. Purified FLAG-VCP and FLAG-VCPg bind human C3b and C4b and blocked complement-mediated hemolysis. Our data suggest that glycosylation did not affect the biological activity of VCP and thus may not have contributed to the attenuation of LC16m8. In addition, the LC16m8 virus likely originated from a substrain of VV-Lister that expresses glycosylated VCP. PMID:25030055

  14. 21 CFR 866.5250 - Complement C2 inhibitor (inactivator) immunological test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... component of complement (a group of serum proteins which destroy infectious agents). Measurement of complement C1 inhibitor aids in the diagnosis of hereditary angioneurotic edema (increased blood...

  15. Immunohistochemical evidence for immunoglobulin and complement deposition in spinal cord lesions in degenerative myelopathy in German shepherd dogs.

    PubMed

    Barclay, K B; Haines, D M

    1994-01-01

    The purpose of this study was to examine the distribution of immunoglobulin and complement component C3 in spinal cord tissues of dogs with degenerative myelopathy. Sections of formalin-fixed paraffin-embedded spinal cord from five German Shepherd dogs with clinical and histological features consistent with degenerative myelopathy (DM) and one normal dog were tested immunohistochemically for deposition of immunoglobulin G (IgG) and the third component of complement (C3). In all dogs there was staining associated with large and small blood vessels. In addition, in the dogs with DM there was focal staining for IgG and C3 in spinal nerve tracts characteristically affected in DM. Deposition of IgG and C3 was found in histological lesions, and in addition, in other areas independent of visible lesions, suggesting that IgG and C3 deposition may precede histological evidence of spinal cord damage. These findings suggest a role for immune-mediated destruction of the spinal cord which may contribute to the pathogenesis of DM in German Shepherd dogs. PMID:8143248

  16. Complementing T-cell Function: An Inhibitory Role of the Complement System in T-cell-Mediated Antitumor Immunity.

    PubMed

    Peng, Weiyi; McKenzie, Jodi A; Hwu, Patrick

    2016-09-01

    New data from Wang and colleagues show that complement C3 suppresses the function of CD8(+) tumor-infiltrating T cells by inhibiting IL10 production, and targeting the complement receptors C3aR and C5aR enhances the antitumor activity of immune checkpoint blockade. Their results not only define a new role of complement receptors as T-cell coinhibitory receptors, but also are useful in the development of novel strategies to improve the effectiveness of cancer immunotherapy. Cancer Discov; 6(9); 953-5. ©2016 AACR.See related article by Wang et al., p. 1022. PMID:27587467

  17. Targeting complement in therapy.

    PubMed

    Kirschfink, M

    2001-04-01

    With increasing evidence that complement activation significantly contributes to the pathogenesis of a large number of inflammatory diseases, strategies that interfere with its deleterious action have become a major focus in pharmacological research. Endogenous soluble complement inhibitors (C1 inhibitor, recombinant soluble complement receptor 1, antibodies) blocking key proteins of the cascade reaction, neutralizing the action of the complement-derived anaphylatoxin C5a, or interfering with complement receptor 3 (CR3, CD18/11b)-mediated adhesion of inflammatory cells to the vascular endothelium have successfully been tested in various animal models over the past years. Promising results consequently led to clinical trials. Furthermore, incorporation of membrane-bound complement regulators (decay-accelerating factor (CD55), membrane co-factor protein (CD46), CD59) in transgenic animals has provided a major step forward in protecting xenografts from hyperacute rejection. At the same time, the poor contribution of complement to the antitumor response, which is caused by multiple resistance mechanisms that hamper the efficacy of antibody-based tumor therapy, is increasingly recognized and requires pharmacologic intervention. First attempts have now been made to interfere with the resistance mechanisms, thereby improving complement-mediated tumor cell destruction. PMID:11414360

  18. Naturally occurring anti-band-3 antibodies and complement together mediate phagocytosis of oxidatively stressed human erythrocytes

    SciTech Connect

    Lutz, H.U.; Bussolino, F.; Flepp, R.; Fasler, S.; Stammler, P.; Kazatchkine, M.D.; Arese, P.

    1987-11-01

    Treatment of erythrocytes with the thiol-specific oxidant azodicarboxylic acid bis(dimethylamide) (diamide) enhances their phagocytosis by adherent monocytes. Phagocytosis of diamide-treated erythrocytes required that the cells were opsonized with whole serum, since complement inactivation abolished phagocytosis. Opsonization with whole serum containing 20-100 times the physiological concentration of naturally occurring anti-band-3- antibodies enhanced phagocytosis of diamide-treated erythrocytes. High inputs of anti-band-3 also restored phagocytosis of erythrocytes that had been incubated with complement-inactivated serum. Elevated concentrations of anti-spectrin antibodies were ineffective in whole and complement-inactivated serum. Specific recognition of diamide-treated erythrocytes by anti-band-3 antibodies may be due to generation of anti-band-3 reactive protein oligomers on intact diamide-treated erythrocytes. Generation of such oligomers was dose-dependent with respect to diamide. Bound anti-band-3 alone was not sufficient to mediate phagocytosis. It resulted in deposition of complement component C3b on the cells through activation of the alternative complement pathway in amounts exceeding that of bound antibodies by two orders of magnitude. Thus, anti-band-3 and complement together mediate phagocytosis of oxidatively stressed erythrocytes, which simulate senescent erythrocytes with respect to bound antibody and complement.

  19. Complement in hemolytic anemia.

    PubMed

    Brodsky, Robert A

    2015-11-26

    Complement is increasingly being recognized as an important driver of human disease, including many hemolytic anemias. Paroxysmal nocturnal hemoglobinuria (PNH) cells are susceptible to hemolysis because of a loss of the complement regulatory proteins CD59 and CD55. Patients with atypical hemolytic uremic syndrome (aHUS) develop a thrombotic microangiopathy (TMA) that in most cases is attributable to mutations that lead to activation of the alternative pathway of complement. For optimal therapy, it is critical, but often difficult, to distinguish aHUS from other TMAs, such as thrombotic thrombocytopenic purpura; however, novel bioassays are being developed. In cold agglutinin disease (CAD), immunoglobulin M autoantibodies fix complement on the surface of red cells, resulting in extravascular hemolysis by the reticuloendothelial system. Drugs that inhibit complement activation are increasingly being used to treat these diseases. This article discusses the pathophysiology, diagnosis, and therapy for PNH, aHUS, and CAD. PMID:26582375

  20. Complement in hemolytic anemia.

    PubMed

    Brodsky, Robert A

    2015-01-01

    Complement is increasingly being recognized as an important driver of human disease, including many hemolytic anemias. Paroxysmal nocturnal hemoglobinuria (PNH) cells are susceptible to hemolysis because of a loss of the complement regulatory proteins CD59 and CD55. Patients with atypical hemolytic uremic syndrome (aHUS) develop a thrombotic microangiopathy (TMA) that in most cases is attributable to mutations that lead to activation of the alternative pathway of complement. For optimal therapy, it is critical, but often difficult, to distinguish aHUS from other TMAs, such as thrombotic thrombocytopenic purpura; however, novel bioassays are being developed. In cold agglutinin disease (CAD), immunoglobulin M autoantibodies fix complement on the surface of red cells, resulting in extravascular hemolysis by the reticuloendothelial system. Drugs that inhibit complement activation are increasingly being used to treat these diseases. This article discusses the pathophysiology, diagnosis, and therapy for PNH, aHUS, and CAD. PMID:26637747

  1. The outer membrane protease PgtE of Salmonella enterica interferes with the alternative complement pathway by cleaving factors B and H.

    PubMed

    Riva, Rauna; Korhonen, Timo K; Meri, Seppo

    2015-01-01

    The virulence factor PgtE is an outer membrane protease (omptin) of the zoonotic pathogen Salmonella enterica that causes diseases ranging from gastroenteritis to severe enteric fever. It is surface exposed in bacteria that have a short-chain, i.e., rough LPS, as observed e.g., in bacteria residing inside macrophages or just emerging from them. We investigated whether PgtE cleaves the complement factors B (B) and H (H), key proteins controlling formation and inactivation of the complement protein C3b and thereby the activity of the complement system. S. enterica serovar Typhimurium or omptin-expressing recombinant E. coli bacteria were incubated with purified human complement proteins or recombinant H fragments. PgtE cleaved both B and H, whereas its close homolog Pla of Yersinia pestis cleaved only H. H was cleaved at both N- and C-termini, while the central region resisted proteolysis. Because of multiple effects of PgtE on complement components (cleavage of C3, C3b, B, and H) we assessed its effect on the opsonophagocytosis of Salmonella. In human serum, C3 cleavage was dependent on proteolytically active PgtE. Human neutrophils interacted less with serum-opsonized FITC-stained S. enterica 14028R than with the isogenic ΔpgtE strain, as analyzed by flow cytometry. In conclusion, cleavage of B and H by PgtE, together with C3 cleavage, affects the C3-mediated recognition of S. enterica by human neutrophils, thus thwarting the immune protection against Salmonella. PMID:25705210

  2. The outer membrane protease PgtE of Salmonella enterica interferes with the alternative complement pathway by cleaving factors B and H

    PubMed Central

    Riva, Rauna; Korhonen, Timo K.; Meri, Seppo

    2015-01-01

    The virulence factor PgtE is an outer membrane protease (omptin) of the zoonotic pathogen Salmonella enterica that causes diseases ranging from gastroenteritis to severe enteric fever. It is surface exposed in bacteria that have a short-chain, i.e., rough LPS, as observed e.g., in bacteria residing inside macrophages or just emerging from them. We investigated whether PgtE cleaves the complement factors B (B) and H (H), key proteins controlling formation and inactivation of the complement protein C3b and thereby the activity of the complement system. S. enterica serovar Typhimurium or omptin-expressing recombinant E. coli bacteria were incubated with purified human complement proteins or recombinant H fragments. PgtE cleaved both B and H, whereas its close homolog Pla of Yersinia pestis cleaved only H. H was cleaved at both N- and C-termini, while the central region resisted proteolysis. Because of multiple effects of PgtE on complement components (cleavage of C3, C3b, B, and H) we assessed its effect on the opsonophagocytosis of Salmonella. In human serum, C3 cleavage was dependent on proteolytically active PgtE. Human neutrophils interacted less with serum-opsonized FITC-stained S. enterica 14028R than with the isogenic ΔpgtE strain, as analyzed by flow cytometry. In conclusion, cleavage of B and H by PgtE, together with C3 cleavage, affects the C3-mediated recognition of S. enterica by human neutrophils, thus thwarting the immune protection against Salmonella. PMID:25705210

  3. Complement levels in acute infectious hepatitis and serum hepatitis

    PubMed Central

    Kosmidis, J. C.; Leader-Williams, Lesley K.

    1972-01-01

    The level of the third component of complement was measured in serial specimens of serum taken from thirty-one patients with acute viral hepatitis. Fourteen of the thirty-one patients were positive for the hepatitis-associated antigen. A characteristic fluctuation was observed in twenty-nine of the thirty-one patients. This consisted of an initial fall of the level of C3, followed by an increase to a higher than normal level and then a gradual return to normal. No difference was observed between the patients who were positive and those who were negative for the hepatitis-associated antigen. These results support the view that immune complexes play a significant role in the pathogenesis of acute viral hepatitis. PMID:4624985

  4. Complement deposition in autoimmune hemolytic anemia is a footprint for difficult-to-detect IgM autoantibodies

    PubMed Central

    Meulenbroek, Elisabeth M.; de Haas, Masja; Brouwer, Conny; Folman, Claudia; Zeerleder, Sacha S.; Wouters, Diana

    2015-01-01

    In autoimmune hemolytic anemia autoantibodies against erythrocytes lead to increased clearance of the erythrocytes, which in turn results in a potentially fatal hemolytic anemia. Depending on whether IgG or IgM antibodies are involved, response to therapy is different. Proper identification of the isotype of the anti-erythrocyte autoantibodies is, therefore, crucial. However, detection of IgM autoantibodies can be challenging. We, therefore, set out to improve the detection of anti-erythrocyte IgM. Direct detection using a flow cytometry-based approach did not yield satisfactory improvements. Next, we analyzed whether the presence of complement C3 on a patient’s erythrocytes could be used for indirect detection of anti-erythrocyte IgM. To this end, we fractionated patients’ sera by size exclusion chromatography and tested which fractions yielded complement deposition on erythrocytes. Strikingly, we found that all patients with C3 on their erythrocytes according to standard diagnostic tests had an IgM anti-erythrocyte component that could activate complement, even if no such autoantibody had been detected with any other test. This also included all tested patients with only IgG and C3 on their erythrocytes, who would previously have been classified as having an IgG-only mediated autoimmune hemolytic anemia. Depleting patients’ sera of either IgG or IgM and testing the remaining complement activation confirmed this result. In conclusion, complement activation in autoimmune hemolytic anemia is mostly IgM-mediated and the presence of covalent C3 on patients’ erythrocytes can be taken as a footprint of the presence of anti-erythrocyte IgM. Based on this finding, we propose a diagnostic workflow that will aid in choosing the optimal treatment strategy. PMID:26354757

  5. The complement system and toll-like receptors as integrated players in the pathophysiology of atherosclerosis.

    PubMed

    Hovland, Anders; Jonasson, Lena; Garred, Peter; Yndestad, Arne; Aukrust, Pål; Lappegård, Knut T; Espevik, Terje; Mollnes, Tom E

    2015-08-01

    Despite recent medical advances, atherosclerosis is a global burden accounting for numerous deaths and hospital admissions. Immune-mediated inflammation is a major component of the atherosclerotic process, but earlier research focus on adaptive immunity has gradually switched towards the role of innate immunity. The complement system and toll-like receptors (TLRs), and the crosstalk between them, may be of particular interest both with respect to pathogenesis and as therapeutic targets in atherosclerosis. Animal studies indicate that inhibition of C3a and C5a reduces atherosclerosis. In humans modified LDL-cholesterol activate complement and TLRs leading to downstream inflammation, and histopathological studies indicate that the innate immune system is present in atherosclerotic lesions. Moreover, clinical studies have demonstrated that both complement and TLRs are upregulated in atherosclerotic diseases, although interventional trials have this far been disappointing. However, based on recent research showing an intimate interplay between complement and TLRs we propose a model in which combined inhibition of both complement and TLRs may represent a potent anti-inflammatory therapeutic approach to reduce atherosclerosis. PMID:26086357

  6. The pathogenesis of arthritis associated with acute hepatitis-B surface antigen-positive hepatitis. Complement activation and characterization of circulating immune complexes.

    PubMed Central

    Wands, J R; Mann, E; Alpert, E; Isselbacher, K J

    1975-01-01

    Circulating immune complexes were identified in cryoproteins isolated from serial samples of serum from six patients with acute viral hepatitis with and without arthritic symptoms. Cryoprecipitates were analyzed for the presence of hepatitis-B surface antigen (HBsAg) and hepatitis-B surface antibody (anti-HBs) by hemagglutination inhibition and hemagglutination. Complement components were detected by counter electrophoresis, and immunoglobulins were detected by gel diffusion. HBsAg, IgG, and IgM were identified in cryoprecipitates from all hepatitis patients, but were higher in concentration in patients with arthritis. Only cryoprecipitates from hepatitis patients with arthritis contained IgA and complement components C3, C4, and C5 as well as IgG and IgM, which disappear with resolution of the arthritis. The subtypes of IgG in these cryoprecipitates were predominantly the complement-fixing IgG1 and IgG3, HBsAg and anti-HBs were concentrated several-fold in the cryoprecipitates when compared to the serum concentration. Sequential studies in two patients demonstrated that the initial appearance of anti-HBs in the cryoprotein complex was associated with the detection in the complex of IgM suggesting a primary immune response to HBsAg. The C3 activator fragment (C3A) of the properdin complex was found in fresh serum obtained from three hepatitis patients with arthritis and not in uncomplicated hepatitis. The cryoprecipitable immune complexes from patients with arthritis converted C3PA in fresh normal sera to C3A in vitro whereas cryoprotein isolated from patients with uncomplicated hepatitis had no such effect. Thus, the transient appearance of circulating complement-fixing immune complexes in patients with the arthritis of acute hepatitis is associated with activation of both classical and alternate complement pathways and suggests that they play an important role in the pathogenesis of these serum sickness-like extrahepatic symptoms. Images PMID:1123429

  7. Depression of Complement Regulatory Factors in Rat and Human Renal Grafts Is Associated with the Progress of Acute T-Cell Mediated Rejection

    PubMed Central

    Yamanaka, Kazuaki; Kakuta, Yoichi; Miyagawa, Shuji; Nakazawa, Shigeaki; Kato, Taigo; Abe, Toyofumi; Imamura, Ryoichi; Okumi, Masayoshi; Maeda, Akira; Okuyama, Hiroomi; Mizuno, Masashi; Nonomura, Norio

    2016-01-01

    Background The association of complement with the progression of acute T cell mediated rejection (ATCMR) is not well understood. We investigated the production of complement components and the expression of complement regulatory proteins (Cregs) in acute T-cell mediated rejection using rat and human renal allografts. Methods We prepared rat allograft and syngeneic graft models of renal transplantation. The expression of Complement components and Cregs was assessed in the rat grafts using quantitative real-time PCR (qRT-PCR) and immunofluorescent staining. We also administered anti-Crry and anti-CD59 antibodies to the rat allograft model. Further, we assessed the relationship between the expression of membrane cofactor protein (MCP) by immunohistochemical staining in human renal grafts and their clinical course. Results qRT-PCR results showed that the expression of Cregs, CD59 and rodent-specific complement regulator complement receptor 1-related gene/protein-y (Crry), was diminished in the rat allograft model especially on day 5 after transplantation in comparison with the syngeneic model. In contrast, the expression of complement components and receptors: C3, C3a receptor, C5a receptor, Factor B, C9, C1q, was increased, but not the expression of C4 and C5, indicating a possible activation of the alternative pathway. When anti-Crry and anti-CD59 mAbs were administered to the allograft, the survival period for each group was shortened. In the human ATCMR cases, the group with higher MCP expression in the grafts showed improved serum creatinine levels after the ATCMR treatment as well as a better 5-year graft survival rate. Conclusions We conclude that the expression of Cregs in allografts is connected with ATCMR. Our results suggest that controlling complement activation in renal grafts can be a new strategy for the treatment of ATCMR. PMID:26928779

  8. Complement Factor H-Related 5-Hybrid Proteins Anchor Properdin and Activate Complement at Self-Surfaces.

    PubMed

    Chen, Qian; Manzke, Melanie; Hartmann, Andrea; Büttner, Maike; Amann, Kerstin; Pauly, Diana; Wiesener, Michael; Skerka, Christine; Zipfel, Peter F

    2016-05-01

    C3 glomerulopathy (C3G) is a severe kidney disease for which no specific therapy exists. The causes of C3G are heterogeneous, and defective complement regulation is often linked to C3G pathogenesis. Copy number variations in the complement factor H-related (CFHR) gene cluster on chromosome 1q32 and CFHR5 mutant proteins associate with this disease. Here, we identified CFHR5 as a pattern recognition protein that binds to damaged human endothelial cell surfaces and to properdin, the human complement activator. We found the two N-terminal short consensus repeat domains of CFHR5 contact properdin and mediate dimer formation. These properdin-binding segments are duplicated in two mutant CFHR5 proteins, CFHR2-CFHR5Hyb from German patients with C3G and CFHR5Dup from Cypriot patients with C3G. Each of these mutated proteins assembled into large multimeric complexes and, compared to CFHR5, bound damaged human cell surfaces and properdin with greater intensity and exacerbated local complement activation. This enhanced surface binding and properdin recruitment was further evidenced in the mesangia of a transplanted and explanted kidney from a German patient with a CFHR2-CFHR5Hyb protein. Enhanced properdin staining correlated with local complement activation with C3b and C5b-9 deposition on the mesangial cell surface in vitro This gain of function in complement activation for two disease-associated CFHR5 mutants describes a new disease mechanism of C3G, which is relevant for defining appropriate treatment options for this disorder. PMID:26432903

  9. Leishmania species: mechanisms of complement activation by five strains of promastigotes.

    PubMed

    Mosser, D M; Burke, S K; Coutavas, E E; Wedgwood, J F; Edelson, P J

    1986-12-01

    The interaction of fresh serum with promastigotes of Leishmania major, L. donovani, L. mexicana mexicana, L. mexicana amazonensis, and L. braziliensis guyanensis results in lysis of all strains tested with either fresh human or guinea pig serum at 37 C for 30 min. Lysis does not occur in the cold and requires divalent cations and complement that is active hemolytically. Serum deficient in the eighth component of complement is not lytic. Lysis of L. major, L. mexicana, and L. braziliensis proceeds fully in human serum containing EGTA/Mg2+ or in guinea pig serum deficient in the fourth complement component. These species consume only small amounts of C4 from human serum and do not require calcium to optimally bind C3. The data indicate that all are activators of the alternative complement pathway and that the classical pathway is not required for the lysis of these organisms. Promastigotes of L. donovani, in contrast, activate the classical pathway. The presence of calcium is required for both optimal C3 binding and parasite lysis, and L. donovani promastigotes consume C4 when incubated in human serum. In high concentrations, human serum agglutinates all tested Leishmania spp. The agglutinating factor does not require divalent cations, is heat stable, and works at 4 C, suggesting that it is an antibody. This "naturally occurring" antibody cross reacts with all Leishmania spp. and agglutinates them. The adsorption of serum with any Leishmania species or with beads that are Protein A coated, removes the agglutinogen. This factor causes a slight enhancement in alternative pathway activation by L. major and mediates the classical activation by L. donovani. In adsorbed serum, L. donovani promastigotes only weakly activate the alternative complement pathway. Increased concentrations of adsorbed serum are therefore necessary for lysis to proceed. The titer can be partially restored by the addition of heat inactivated serum. Using purified components of the classical cascade

  10. Hyperglycemic conditions inhibit C3-mediated immunologic control of Staphylococcus aureus

    PubMed Central

    2012-01-01

    Background Diabetic patients are at increased risk for bacterial infections; these studies provide new insight into the role of the host defense complement system in controlling bacterial pathogens in hyperglycemic environments. Methods The interactions of complement C3 with bacteria in elevated glucose were assayed for complement activation to opsonic forms, phagocytosis and bacterial killing. C3 was analyzed in euglycemic and hyperglycemic conditions by mass spectrometry to measure glycation and structural differences. Results Elevated glucose inhibited S. aureus activation of C3 and deposition of C3b and iC3b on the bacterial surface. S. aureus-generated C5a and serum-mediated phagocytosis by neutrophils were both decreased in elevated glucose conditions. Interestingly, elevated glucose increased the binding of unactivated C3 to S. aureus, which was reversible on return to normal glucose concentrations. In a model of polymicrobial infection, S. aureus in elevated glucose conditions depleted C3 from serum resulting in decreased complement-mediated killing of E. coli. To investigate the effect of differing glucose concentration on C3 structure and glycation, purified C3 incubated with varying glucose concentrations was analyzed by mass spectrometry. Glycation was limited to the same three lysine residues in both euglycemic and hyperglycemic conditions over one hour, thus glycation could not account for observed changes between glucose conditions. However, surface labeling of C3 with sulfo-NHS-biotin showed significant changes in the surface availability of seven lysine residues in response to increasing glucose concentrations. These results suggest that the tertiary structure of C3 changes in response to hyperglycemic conditions leading to an altered interaction of C3 with bacterial pathogens. Conclusions These results demonstrate that hyperglycemic conditions inhibit C3-mediated complement effectors important in the immunological control of S. aureus. Mass

  11. CSF coccidioides complement fixation

    MedlinePlus

    ... eds. Henry's Clinical Diagnosis and Management by Laboratory Methods . 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 61. Read More Complement Update Date 5/1/2015 Updated by: Jatin M. Vyas, MD, ...

  12. Discrimination between activators and nonactivators of the alternative pathway of complement: Regulation via a sialic acid/polyanion binding site on factor H

    SciTech Connect

    Meri, S.; Pangburn, M.K. )

    1990-05-01

    The alternative complement pathway is capable of discriminating human cells and tissues from a wide variety of potential pathogens. It has been recently demonstrated that attachment of complement component C3b to activator-derived molecules restricts inactivation of C3b by factors H and I in a manner similar to activator surfaces. It is now shown that restriction is reversed by certain soluble polyanions that mimic the effects of sialic acid and glycosaminoglycans on human cells and tissues. Fluid-phase polyanions enhanced binding of factor H to C3b attached to activating particles, indicating that the effect resulted from increased affinity between C3b and factor H. The enhancement was specific for activator-bound C3b since no enhancement was observed on nonactivating particles. While several polyanions could cause this effect, some polyanions could not, indicating specificity. The active polyanions also inhibited lysis of cells via the alternative pathway. The binding site for sialic acid appears to reside on factor H, since factor H bound to heparin-agarose and to sialic acid-bearing fetuinagarose, whereas C3b bound to neither under the same conditions. These observation suggest that occupation of a specific site on factor H by polyanions induces an increase in the C3b-H affinity, resulting in discrimination of host cells and tissues from alternative pathway-activating foreign cells.

  13. Study of five haemogenetic markers (Gc, C3, Bf, Ag, and GALT) in six Indonesian populations and in 12 subgroups of Balinese.

    PubMed

    Scherz, R; Breguet, G; Ney, R; Pflugshaupt, R; Bütler, R

    1988-08-01

    In various ethnic groups of the Indonesian archipelago and of Bali, the polymorphisms of the serum proteins Gc globulin (vitamin D-binding protein), C3 (complement component 3), Bf (complement factor B), Ag x,y (lipoprotein allotypes), and of the red cell enzyme system GALT (galactose-1P-uridyltransferase) were analysed. Among the studied proteins, the Gc system was the most informative one for the anthropologist. Besides considerable differences of frequencies of the common alleles Gc*1F, Gc*1S and Gc*2, a number of rare alleles (1A1, 1A3, 1A8, 1A9, 1A12, 1C2, 1C21, 1C24, and 2C8) and some new ones (1C28, 1C29, 1C30, 2C9) were observed. The presence of Gc*1A1 demonstrates the relationship to the Australo-Melanesian populations, but Mongolian variants (1A3, 1A8, 1A9, 1C2) were also encountered. Within the C3 system a very high frequency of the C3*S allele was observed in all populations. The rare alleles C3*F0.55, C3S1, and C3*S0.5 were observed in some groups. A new allele (C3*F0.35) was detected in a Chinese individual and in a nobleman from Bali. The frequency of the Bf*F allele was rather low in general, and the Bf*S0.7 allele was found in three Indonesian individuals only. The Ag*(x) frequencies were rather high, as it is known for Asiatic populations. Variability among subgroups was not very pronounced. The GALT*2 allele (Duarte variant of the enzyme) was observed very rarely; however, it was present in several populations. Enzyme activities could not be determined, and therefore we cannot tell whether the galactosaemia gene (GALT*0) was present or not. PMID:2851268

  14. Revisiting post-infectious glomerulonephritis in the emerging era of C3 glomerulopathy

    PubMed Central

    Khalighi, Mazdak A.; Wang, Shihtien; Henriksen, Kammi J.; Bock, Margret; Keswani, Mahima; Meehan, Shane M.; Chang, Anthony

    2016-01-01

    Background Post-infectious glomerulonephritis (PIGN) is an immune complex-mediated glomerular injury that typically resolves. Dominant C3 deposition is characteristic of PIGN, but with the emergence of C3 glomerulonephritis (C3GN) as a distinct entity, it is unclear how the pathologic similarities between PIGN and C3GN should be reconciled. Therefore, nephrologists and nephropathologists need additional guidance at the time of biopsy. Methods We studied 23 pediatric and young adult patients diagnosed with PIGN. Patients were divided into two groups, one with co-dominance between C3 and immunoglobulins and the other meeting proposed diagnostic criteria for C3GN. Clinical and pathological features were compared. Results No clinical and/or pathological features could distinguish between those with C3-co-dominant deposits and those with C3 dominance. Nearly all patients in both groups regained their baseline renal function without clinical intervention. Conclusions Although the identification of abnormalities of the alternative pathway of complement is characteristic of C3GN, testing is not widely available and the turnaround time often exceeds 1 month. Our study found that PIGN with either co-dominant or dominant C3 deposition in a cohort of young patients has excellent short-term outcomes. Close clinical observation for persistent abnormalities, such as hypocomplementemia, prolonged hematuria or proteinuria, is recommended to single out patients that may harbor intrinsic complement abnormalities. PMID:27274823

  15. Degradation of Complement 3 by Streptococcal Pyrogenic Exotoxin B Inhibits Complement Activation and Neutrophil Opsonophagocytosis▿

    PubMed Central

    Kuo, Chih-Feng; Lin, Yee-Shin; Chuang, Woei-Jer; Wu, Jiunn-Jong; Tsao, Nina

    2008-01-01

    Streptococcal pyrogenic exotoxin B (SPE B), a cysteine protease, is an important virulence factor in group A streptococcus (GAS) infection. The inhibition of phagocytic activity by SPE B may help prevent bacteria from being ingested. In this study, we examined the mechanism SPE B uses to enable bacteria to resist opsonophagocytosis. Using an enzyme-linked immunosorbent assay, we found that SPE B-treated serum impaired the activation of the classical, the lectin, and the alternative complement pathways. In contrast, C192S, a SPE B mutant lacking protease activity, had no effect on complement activation. Further study showed that cleavage of serum C3 by SPE B, but not C192S, blocked zymosan-induced production of reactive oxygen species in neutrophils as a result of decreased deposition of C3 fragments on the zymosan surface. Reconstitution of C3 into SPE B-treated serum unblocked zymosan-mediated neutrophil activation dose dependently. SPE B-treated, but not C192S-treated, serum also impaired opsonization of C3 fragments on the surface of GAS strain A20. Moreover, the amount of C3 fragments on the A20 cell surface, a SPE B-producing strain, was less than that on its isogenic mutant strain, SW507, after opsonization with normal serum. A20 opsonized with SPE B-treated serum was more resistant to neutrophil killing than A20 opsonized with normal serum, and SPE B-mediated resistance was C3 dependent. These results suggest a novel SPE B mechanism, one which degrades serum C3 and enables GAS to resist complement damage and opsonophagocytosis. PMID:18174338

  16. A co-operative interaction between Neisseria gonorrhoeae and complement receptor 3 mediates infection of primary cervical epithelial cells.

    PubMed

    Edwards, Jennifer L; Brown, Eric J; Uk-Nham, Sang; Cannon, Janne G; Blake, Milan S; Apicella, Michael A

    2002-09-01

    Little is known about the pathogenesis of gonococcal infection within the lower female genital tract. We recently described the distribution of complement receptor 3 (CR3) on epithelia of the female genital tract. Our studies further indicate that CR3-mediated endocytosis serves as a primary mechanism by which N. gonorrhoeae elicits membrane ruffling and cellular invasion of primary, human, cervical epithelial cells. We have extended these studies to describe the nature of the gonococcus-CR3 interaction. Western Blot analysis demonstrated production of alternative pathway complement components by ecto- and endocervical cells which allows C3b deposition on gonococci and its rapid conversion to iC3b. Anti-iC3b and -factor I antibodies significantly inhibited adherence and invasion of primary cervical cells, suggesting that iC3b covalently bound to the gonococcus serves as a primary ligand for CR3 adherence. However, gonococcal porin and pili also bound to the I-domain of CR3 in a non-opsonic manner. Binding of porin and pili to CR3 were required for adherence to and invasion of cervical epithelia. Collectively, these data suggest that gonococcal adherence to CR3 occurs in a co-operative manner, which requires gonococcal iC3b-opsonization, porin and pilus. In conjunction, these molecules facilitate targeting to and successful infection of the cervical epithelium. PMID:12390350

  17. Extinct I-129 in C3 chondrites

    NASA Technical Reports Server (NTRS)

    Crabb, J.; Lewis, R. S.; Anders, E.

    1982-01-01

    Eight C3 chondrites were examined by the I-129 to Xe-129 dating method to determine whether their initial I-129/I-127 ratios, or R(0), correlate with any other properties. The R(0)'s range from 1.60 x 10 to the -4th to 1.09 x 10 to the -4th, corresponding to I to Xe ages from 2.0 Myr before to 6.7 Myr after the Murchison magnetite. Three C30's have essentially indistinguishable R(0)'s, while a fourth is undatable. Four C3V's show a distinct spread, ranging from 1.60 + or 0.07 x 10 to the -4th to 1.09 + or - 0.10 x 10 to the -4th. These R(0)'s correlate inversely with four other properties: I, Br, and Cd content, olivine composition, both percent mean deviation, and proportion of iron-poor olivine grains. The simplest model that accounts for the correlations with R(0) involves mixing of two iodine components in the solar nebula, associated with gas and grains, respectively. The second, of lower I-129/I-127 ratio, predominated at later times and thus became enriched in late-formed meteorites.

  18. Complement and cytokine response in acute Thrombotic Thrombocytopenic Purpura

    PubMed Central

    Westwood, John-Paul; Langley, Kathryn; Heelas, Edward; Machin, Samuel J; Scully, Marie

    2014-01-01

    Complement dysregulation is key in the pathogenesis of atypical Haemolytic Uraemic Syndrome (aHUS), but no clear role for complement has been identified in Thrombotic Thrombocytopenic Purpura (TTP). We aimed to assess complement activation and cytokine response in acute antibody-mediated TTP. Complement C3a and C5a and cytokines (interleukin (IL)-2, IL-4, IL-6, IL-10, tumour necrosis factor, interferon-γ and IL-17a) were measured in 20 acute TTP patients and 49 remission cases. Anti-ADAMTS13 immunoglobulin G (IgG) subtypes were measured in acute patients in order to study the association with complement activation. In acute TTP, median C3a and C5a were significantly elevated compared to remission, C3a 63·9 ng/ml vs. 38·2 ng/ml (P < 0·001) and C5a 16·4 ng/ml vs. 9·29 ng/ml (P < 0·001), respectively. Median IL-6 and IL-10 levels were significantly higher in the acute vs. remission groups, IL-6: 8 pg/ml vs. 2 pg/ml (P = 0·003), IL-10: 6 pg/ml vs. 2 pg/ml (P < 0·001). C3a levels correlated with both anti-ADAMTS13 IgG (rs = 0·604, P = 0·017) and IL-10 (rs = 0·692, P = 0·006). No anti-ADAMTS13 IgG subtype was associated with higher complement activation, but patients with the highest C3a levels had 3 or 4 IgG subtypes present. These results suggest complement anaphylatoxin levels are higher in acute TTP cases than in remission, and the complement response seen acutely may relate to anti-ADAMTS13 IgG antibody and IL-10 levels. PMID:24372446

  19. A1BG and C3 are overexpressed in patients with cervical intraepithelial neoplasia III

    PubMed Central

    CANALES, NORMA ANGÉLICA GALICIA; MARINA, VICENTE MADRID; CASTRO, JORGE SALMERÓN; JIMÉNEZ, ALFREDO ANTÚNEZ; MENDOZA-HERNÁNDEZ, GUILLERMO; McCARRON, ELIZABETH LANGLEY; ROMAN, MARGARITA BAHENA; CASTRO-ROMERO, JULIETA IVONE

    2014-01-01

    The present study aimed to analyze sera proteins in females with cervical intraepithelial neoplasia, grade III (CIN III) and in healthy control females, in order to identify a potential biomarker which detects lesions that have a greater probability of cervical transformation. The present study investigated five sera samples from females who were Human Papilloma Virus (HPV) 16+ and who had been histopathologically diagnosed with CIN III, as well as five sera samples from healthy control females who were HPV-negative. Protein separation was performed using two-dimensional (2D) gel electrophoresis and the proteins were stained with Colloidal Coommassie Blue. Quantitative analysis was performed using ImageMaster 2D Platinum 6.0 software. Peptide sequence identification was performed using a nano-LC ESIMS/MS system. The proteins with the highest Mascot score were validated using western blot analysis in an additional 55 sera samples from the control and CIN III groups. The eight highest score spots that were found to be overexpressed in the CIN III sera group were identified as α-1-B glycoprotein (A1BG), complement component 3 (C3), a pro-apolipoprotein, two apolipoproteins and three haptoglobins. Only A1BG and C3 were validated using western blot analysis, and the bands were compared between the two groups using densitometry analysis. The relative density of the bands of A1BG and C3 was found to be greater in all of the serum samples from the females with CIN III, compared with those of the individuals in the control group. In summary, the present study identified two proteins whose expression was elevated in females with CIN III, suggesting that they could be used as biomarkers for CIN III. However, further investigations are required in order to assess the expression of A1BG and C3 in different pre-malignant lesions. PMID:25009667

  20. Modular variations of the human major histocompatibility complex class III genes for serine/threonine kinase RP, complement component C4, steroid 21-hydroxylase CYP21, and tenascin TNX (the RCCX module). A mechanism for gene deletions and disease associations.

    PubMed

    Yang, Z; Mendoza, A R; Welch, T R; Zipf, W B; Yu, C Y

    1999-04-23

    The frequent variations of human complement component C4 gene size and gene numbers, plus the extensive polymorphism of the proteins, render C4 an excellent marker for major histocompatibility complex disease associations. As shown by definitive RFLPs, the tandemly arranged genes RP, C4, CYP21, and TNX are duplicated together as a discrete genetic unit termed the RCCX module. Duplications of the RCCX modules occurred by the addition of genomic fragments containing a long (L) or a short (S) C4 gene, a CYP21A or a CYP21B gene, and the gene fragments TNXA and RP2. Four major RCCX structures with bimodular L-L, bimodular L-S, monomodular L, and monomodular S are present in the Caucasian population. These modules are readily detectable by TaqI RFLPs. The RCCX modular variations appear to be a root cause for the acquisition of deleterious mutations from pseudogenes or gene segments in the RCCX to their corresponding functional genes. In a patient with congenital adrenal hyperplasia, we discovered a TNXB-TNXA recombinant with the deletion of RP2-C4B-CYP21B. Elucidation of the DNA sequence for the recombination breakpoint region and sequence analyses yielded definitive proof for an unequal crossover between TNXA from a bimodular chromosome and TNXB from a monomodular chromosome. PMID:10207042

  1. Complement Activation Is Required for Induction of a Protective Antibody Response against West Nile Virus Infection

    PubMed Central

    Mehlhop, Erin; Whitby, Kevin; Oliphant, Theodore; Marri, Anantha; Engle, Michael; Diamond, Michael S.

    2005-01-01

    Infection with West Nile virus (WNV) causes a severe infection of the central nervous system (CNS) with higher levels of morbidity and mortality in the elderly and the immunocompromised. Experiments with mice have begun to define how the innate and adaptive immune responses function to limit infection. Here, we demonstrate that the complement system, a major component of innate immunity, controls WNV infection in vitro primarily in an antibody-dependent manner by neutralizing virus particles in solution and lysing WNV-infected cells. More decisively, mice that genetically lack the third component of complement or complement receptor 1 (CR1) and CR2 developed increased CNS virus burdens and were vulnerable to lethal infection at a low dose of WNV. Both C3-deficient and CR1- and CR2-deficient mice also had significant deficits in their humoral responses after infection with markedly reduced levels of specific anti-WNV immunoglobulin M (IgM) and IgG. Overall, these results suggest that complement controls WNV infection, in part through its ability to induce a protective antibody response. PMID:15919902

  2. Infliximab treatment reduces complement activation in patients with rheumatoid arthritis

    PubMed Central

    Familian, A; Voskuyl, A; van Mierlo, G J; Heijst, H; Twisk, J; Dijkmans, B; Hack, C

    2005-01-01

    Background: Tumour necrosis factor (TNF) blocking agents decrease C reactive protein (CRP) levels in rheumatoid arthritis (RA). It has been shown that CRP may contribute to complement activation in RA. Objective: To assess the effect of intravenous infliximab treatment on complement activation, especially that mediated by CRP, in RA. Methods: 35 patients with active RA (28 joint count Disease Activity Score (DAS28) >4.4) were treated with intravenous injections of infliximab (3 mg/kg, at weeks 0, 2, 6, 14, and 22). Clinical response and plasma levels of complement activation products, of CRP and of CRP-complement complexes, which are specific markers for CRP mediated complement activation, were assessed at the indicated time points up to 22 weeks. The relationship between CRP and CRP-complement complexes was analysed by paired t test between two time points and by generalised estimated equation, to test differences of variables over time. Results: At 2 weeks after the first dose, infliximab significantly reduced overall C3 and C4 activation and plasma levels of CRP and CRP-complement complexes were also significantly reduced at this time point. The effects of infliximab on CRP and complement continued throughout the observation period and were more pronounced in patients with a good response to infliximab treatment. Conclusion: Treatment with infliximab decreases plasma levels of CRP and CRP dependent complement activation products and concomitantly may reduce complement activation in RA. Complement activation may be among the effector mechanisms of TNF in RA. PMID:15958758

  3. Acquisition of regulators of complement activation by Streptococcus pyogenes serotype M1.

    PubMed

    Pandiripally, Vinod; Gregory, Eugene; Cue, David

    2002-11-01

    Opsonization of bacteria by complement proteins is an important component of the immune response. The pathogenic bacterium Streptococcus pyogenes has evolved multiple mechanisms for the evasion of complement-mediated opsonization. One mechanism involves the binding of human regulators of complement activation such as factor H (FH) and FH-like protein 1 (FHL-1). Acquisition of these regulatory proteins can limit deposition of the opsonin C3b on bacteria, thus decreasing the pathogen's susceptibility to phagocytosis. Binding of complement regulatory proteins by S. pyogenes has previously been attributed to the streptococcal M and M-like proteins. Here, we report that the S. pyogenes cell surface protein Fba can mediate binding of FH and FHL-1. We constructed mutant derivatives of S. pyogenes that lack Fba, M1 protein, or both proteins and assayed the strains for FH binding, susceptibility to phagocytosis, and C3 deposition. Fba expression was found to be sufficient for binding of purified FH as well as for binding of FH and FHL-1 from human plasma. Plasma adsorption experiments also revealed that M1(+) Fba(+) streptococci preferentially bind FHL-1, whereas M1(-) Fba(+) streptococci have similar affinities for FH and FHL-1. Fba was found to contribute to the survival of streptococci incubated with human blood and to inhibit C3 deposition on bacterial cells. Streptococci harvested from log-phase cultures readily bound FH, but binding was greatly reduced for bacteria obtained from stationary-phase cultures. Bacteria cultured in the presence of the protease inhibitor E64 maintained FH binding activity in stationary phase, suggesting that Fba is removed from the cell surface via proteolysis. Western analyses confirmed that E64 stabilizes cell surface expression of Fba. These data indicate that Fba is an antiopsonic, antiphagocytic protein that may be regulated by cell surface proteolysis. PMID:12379699

  4. Acquisition of Regulators of Complement Activation by Streptococcus pyogenes Serotype M1

    PubMed Central

    Pandiripally, Vinod; Gregory, Eugene; Cue, David

    2002-01-01

    Opsonization of bacteria by complement proteins is an important component of the immune response. The pathogenic bacterium Streptococcus pyogenes has evolved multiple mechanisms for the evasion of complement-mediated opsonization. One mechanism involves the binding of human regulators of complement activation such as factor H (FH) and FH-like protein 1 (FHL-1). Acquisition of these regulatory proteins can limit deposition of the opsonin C3b on bacteria, thus decreasing the pathogen's susceptibility to phagocytosis. Binding of complement regulatory proteins by S. pyogenes has previously been attributed to the streptococcal M and M-like proteins. Here, we report that the S. pyogenes cell surface protein Fba can mediate binding of FH and FHL-1. We constructed mutant derivatives of S. pyogenes that lack Fba, M1 protein, or both proteins and assayed the strains for FH binding, susceptibility to phagocytosis, and C3 deposition. Fba expression was found to be sufficient for binding of purified FH as well as for binding of FH and FHL-1 from human plasma. Plasma adsorption experiments also revealed that M1+ Fba+ streptococci preferentially bind FHL-1, whereas M1− Fba+ streptococci have similar affinities for FH and FHL-1. Fba was found to contribute to the survival of streptococci incubated with human blood and to inhibit C3 deposition on bacterial cells. Streptococci harvested from log-phase cultures readily bound FH, but binding was greatly reduced for bacteria obtained from stationary-phase cultures. Bacteria cultured in the presence of the protease inhibitor E64 maintained FH binding activity in stationary phase, suggesting that Fba is removed from the cell surface via proteolysis. Western analyses confirmed that E64 stabilizes cell surface expression of Fba. These data indicate that Fba is an antiopsonic, antiphagocytic protein that may be regulated by cell surface proteolysis. PMID:12379699

  5. Role of the lectin complement pathway in kidney transplantation.

    PubMed

    Farrar, Conrad A; Zhou, Wuding; Sacks, Steven H

    2016-10-01

    In the last 15 years two major advances in the role of complement in the kidney transplant have come about. The first is that ischaemia reperfusion injury and its profound effect on transplant outcome is dependent on the terminal product of complement activation, C5b-9. The second key observation relates to the function of the small biologically active fragments C3a and C5a released by complement activation in increasing antigen presentation and priming the T cell response that results in transplant rejection. In both cases local synthesis of C3 principally by the renal tubule cells plays an essential role that overshadows the role of the circulating pool of C3 generated largely by hepatocyte synthesis. More recent efforts have investigated the molecules expressed by renal tissue that can trigger complement activation. These have revealed a prominent effect of collectin-11 (CL-11), a soluble C-type lectin that is expressed in renal tissue and aligns with its major ligand L-fucose at sites of complement activation following ischaemic stress. Biochemical studies have shown that interaction between CL-11 and L-fucose results in complement activation by the lectin complement pathway, precisely targeting the innate immune response to the ischaemic tubule surface. Therapeutic approaches to reduce inflammatory and immune stimulation in ischaemic kidney have so far targeted C3 or its activation products and several are in clinical trials. The finding that lectin-fucose interaction is an important trigger of lectin pathway complement activation within the donor organ opens up further therapeutic targets where intervention could protect the donor kidney against complement. PMID:27286717

  6. Host Specificity of Ovine Bordetella parapertussis and the Role of Complement

    PubMed Central

    Hester, Sara E.; Goodfield, Laura L.; Park, Jihye; Feaga, Heather A.; Ivanov, Yury V.; Bendor, Liron; Taylor, Dawn L.; Harvill, Eric T.

    2015-01-01

    The classical bordetellae are comprised of three subspecies that differ from broad to very limited host specificity. Although several lineages appear to have specialized to particular host species, most retain the ability to colonize and grow in mice, providing a powerful common experimental model to study their differences. One of the subspecies, Bordetella parapertussis, is composed of two distinct clades that have specialized to different hosts: one to humans (Bpphu), and the other to sheep (Bppov). While Bpphu and the other classical bordetellae can efficiently colonize mice, Bppov strains are severely defective in their ability to colonize the murine respiratory tract. Bppov genomic analysis did not reveal the loss of adherence genes, but substantial mutations and deletions of multiple genes involved in the production of O-antigen, which is required to prevent complement deposition on B. bronchiseptica and Bpphu strains. Bppov lacks O-antigen and, like O-antigen mutants of other bordetellae, is highly sensitive to murine complement-mediated killing in vitro. Based on these results, we hypothesized that Bppov failed to colonize mice because of its sensitivity to murine complement. Consistent with this, the Bppov defect in the colonization of wild type mice was not observed in mice lacking the central complement component C3. Furthermore, Bppov strains were highly susceptible to killing by murine complement, but not by sheep complement. These data demonstrate that the failure of Bppov to colonize mice is due to sensitivity to murine, but not sheep, complement, providing a mechanistic example of how specialization that accompanies expansion in one host can limit host range. PMID:26158540

  7. Humoral response to herpes simplex virus is complement-dependent

    PubMed Central

    Da Costa, Xavier J.; Brockman, Mark A.; Alicot, Elisabeth; Ma, Minghe; Fischer, Michael B.; Zhou, Xioaning; Knipe, David M.; Carroll, Michael C.

    1999-01-01

    The complement system represents a cascade of serum proteins, which provide a major effector function in innate immunity. Recent studies have revealed that complement links innate and adaptive immunity via complement receptors CD21/CD35 in that it enhances the B cell memory response to noninfectious protein antigens introduced i.v. To examine the importance of complement for immune responses to virus infection in a peripheral tissue, we compared the B cell memory response of mice deficient in complement C3, C4, or CD21/CD35 with wild-type controls. We found that the deficient mice failed to generate a normal memory response, which is characterized by a reduction in IgG antibody and germinal centers. Thus, complement is important not only in the effector function of innate immunity but also in the stimulation of memory B cell responses to viral-infected cell antigens in both blood and peripheral tissues. PMID:10535987

  8. Hypomorphic variant of the slow allele of C3 associated with hypocomplementemia and hematuria.

    PubMed

    McLean, R H; Bryan, R K; Winkelstein, J

    1985-05-01

    This report describes the first instance of a hypomorphic variant (C3*s) of the most common C3 allele, C3 Slow, which was detected in a four-year-old Caucasian boy with hematuria. Analysis of C3 phenotypes, as determined by agarose electrophoresis, showed a hypomorphic C3 Slow in the patient and a maternal aunt. Serum C3 concentration was significantly reduced in the patient and his mother (610 and 750 micrograms/ml; normal +/- 1 SD = 1,240 +/- 240 micrograms/ml) and was at the lower limits of normal in the affected aunt (770 micrograms/ml). The mother's phenotype was C3 S (? Ss) and she was the presumed carrier, since the father (C3 FS) had neither an abnormal C3 S band nor a low C3 concentration (980 micrograms/ml). Total hemolytic complement was significantly reduced only in the patient (19 units/ml; normal = 38 +/- 16). Hypomorphic C3 variants should be considered in the evaluation of decreased serum C3 levels. PMID:3993666

  9. C1-bypass complement-activation pathway in patients with chronic urticaria and angio-oedema.

    PubMed

    Ballow, M; Ward, G W; Gershwin, M E; Day, N K

    1975-08-01

    During the routine screening of 152 patients with urticaria or angio-oedema for hypocomplementaemia, 4 patients were found to have low serum levels of the third component of complement (C). These patients were noteworthy and differed from previous reports of patients with urticaria-like skin lesions and hypocomplementaemia because of the absence of immune-complex disease. In addition to the low C3, 2 of these patients were unique on the basis of low serum levels of haemolytic C1, C1q, C1s, and properdin factor B, but normal concentrations of C4 and C2. These C abnormalities may reflect a new clinical entity, and these cases form the first description in man of the C1-bypass complement-activation pathway. PMID:49798

  10. Chronic Low Level Complement Activation within the Eye Is Controlled by Intraocular Complement Regulatory Proteins

    PubMed Central

    Sohn, Jeong-Hyeon; Kaplan, Henry J.; Suk, Hye-Jung; Bora, Puran S.; Bora, Nalini S.

    2007-01-01

    Purpose To explore the role of the complement system and complement regulatory proteins in an immune-privileged organ, the eye. Methods Eyes of normal Lewis rats were analyzed for the expression of complement regulatory proteins, membrane cofactor protein (MCP), decay-acceleration factor (DAF), membrane inhibitor of reactive lysis (MIRL, CD59), and cell surface regulator of complement (Crry), using immunohistochemistry, Western blot analysis, and reverse transcription–polymerase chain reaction (RT-PCR). Zymosan, a known activator of the alternative pathway of complement system was injected into the anterior chamber of the eye of Lewis rats. Animals were also injected intracamerally with 5 μl (25 μg) of neutralizing monoclonal antibody (mAb) against rat Crry (5I2) or CD59 (6D1) in an attempt to develop antibody induced anterior uveitis; control animals received 5 μl of sterile phosphate-buffered saline (PBS), OX-18 (25 μg), G-16-510E3 (25 μg), or MOPC-21 (25 μg). The role of complement system in antibody-induced uveitis was explored by intraperitoneal injection of 35 U cobra venom factor (CVF), 24 hours before antibody injection. Immunohistochemical staining and sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) with Western blot analysis were used to detect the presence of membrane attack complex (MAC) and C3 activation products, respectively, in normal and antibody-injected rat eyes. Results Complement activation product MAC was present in the normal rat eye, and intraocular injection of zymosan induced severe anterior uveitis. The complement regulatory proteins, MCP, DAF, CD59, and Crry, were identified in the normal rat eye. Soluble forms of Crry and CD59 were also detected in normal rat aqueous humor. Severe anterior uveitis developed in Lewis rats injected with a neutralizing mAb against Crry, with increased formation of C3 split products. Systemic complement depletion by CVF prevented the induction of anterior uveitis by anti

  11. [Demonstration of C3-binding circulating immune complexes using Raji, conglutinin and anti-C3 assays--a critical review].

    PubMed

    Arndt, R

    1984-02-01

    There remains no doubt at the present time, that the appearance of circulating immune complexes in illness accompanying vasculitis and for glomerulonephritis correlates with the severity of disease. Moreover, immune complexes are of diagnostic importance where infections with a chronic development or neoplastic diseases are concerned. The choice of IC test system should incorporate their essential biological functions and identify those IC that activate the complement cascade both by the classical and the alternative route. The detection of IC bound C3 cleavage products (C3b, C3bi, C3d) represents the key to identification of a wide range of IC. Of the presently available methods Raji cell test, conglutinin- and anti C3-IC assay, on critical appraisal, the anti C3-IC assay represents the most applicable way of defining complement binding IC. The advantage of this system is that appreciable disturbances and limitations that influence other systems do not affect the antigen-antibody reaction which is the core of the anti C3 assay. PMID:6241918

  12. 42 CFR 52c.3 - Eligibility.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Eligibility. 52c.3 Section 52c.3 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS MINORITY BIOMEDICAL RESEARCH SUPPORT PROGRAM § 52c.3 Eligibility. To be eligible for a grant under this Program, an applicant must...

  13. 42 CFR 52c.3 - Eligibility.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Eligibility. 52c.3 Section 52c.3 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS MINORITY BIOMEDICAL RESEARCH SUPPORT PROGRAM § 52c.3 Eligibility. To be eligible for a grant under this Program, an applicant must...

  14. 42 CFR 52c.3 - Eligibility.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Eligibility. 52c.3 Section 52c.3 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS MINORITY BIOMEDICAL RESEARCH SUPPORT PROGRAM § 52c.3 Eligibility. To be eligible for a grant under this Program, an applicant must...

  15. C(3)-cyclopropyl cephems and carbacephems.

    PubMed

    Spry, D O; Snyder, N J; Kasher, J S

    1989-11-01

    A series of C(3)-cyclopropyl cephems and carbacephems has been prepared by palladium catalyzed addition of diazomethane to the corresponding C(3)-vinyl derivatives. The phenylglycyl cyclopropyl cephem derivatives exhibit better Gram-positive activity than cephalexin or cefaclor, while the aminothiazole oxime cyclopropyl cephem derivatives were not as active as the corresponding C(3)-vinyl cephems. PMID:2584150

  16. The Importance of the C3 Framework

    ERIC Educational Resources Information Center

    Social Education, 2013

    2013-01-01

    "The C3 Framework for Social Studies State Standards will soon be released under the title "The College, Career, and Civic Life (C3) Framework for Social Studies State Standards: State Guidance for Enhancing the Rigor of K-12 Civics, Economics, Geography, and History." The C3 Project Director and Lead Writer was NCSS member Kathy…

  17. The role of the complement system in innate immunity.

    PubMed

    Rus, Horea; Cudrici, Cornelia; Niculescu, Florin

    2005-01-01

    Complement is a major component of innate immune system involved in defending against all the foreign pathogens through complement fragments that participate in opsonization, chemotaxis, and activation of leukocytes and through cytolysis by C5b-9 membrane attack complex. Bacterias and viruses have adapted in various ways to escape the complement activation, and they take advantage of the complement system by using the host complement receptors to infect various cells. Complement activation also participates in clearance of apoptotic cells and immune complexes. Moreover, at sublytic dose, C5b-9 was shown to promote cell survival. Recently it was also recognized that complement plays a key role in adaptive immunity by modulating and modifying the T cell responses. All these data suggest that complement activation constitutes a critical link between the innate and acquired immune responses. PMID:16234578

  18. Immune adherence in renal glomeruli. Complement receptor sites on glomerular capillary epithelial cells.

    PubMed Central

    Burkholder, P. M.; Oberley, T. D.; Barber, T. A.; Beacom, A.; Koehler, C.

    1977-01-01

    Several very recent reports have indicated the presence of receptor sites for the third component of complement in human but not other vertebrate renal glomeruli. The present study constitutes a demonstration that the glomerular capillary epithelial cell bears this receptor, detectable with either EAC complexes (EAC1423b) or fluores ceinated zymosan-C3 (ZC3b) complexes, Fresh, unfixed frozen sections of normal or diseased human kidneys, mechanically isolated human glomeruli, dissociated glomerular cells, and glomeruli and golmerular cells maintained in tissue culture were examined with various EAC complexes or ZC3b and examined by phase light microscopy, fluorescence microscopy, or transmission and scanning electron microscopy. Clearly, by scanning electron microscopy it was determined that glomerular capillary epithelial cells bind the immune-adherence EAC indicator cells. Because glomeruli or glomerular epithelial cells did not bind E, EA, EACI, EAC14, or EAC142 but did bind EAC1423b or ZC3b, it is concluded that C3b (activated bound fragment of the third component of complement) is responsible for the immune-adherence reaction in glomeruli. Preliminary examination of diseased renal biopsies indicates that sclerotic glomeruli, focal segmental sclerotic or proliferative glomerular capillary lesions, and proliferative epithelial crescents are immune-adherence negative. Furthermore, a clear or consistent inverse relationship between glomerular capillary deposits of C3 which presumably might block epithelial C3 receptor sites, and immune-adherence reactivity with EAC in vitro was not as evident in this study as reported previously by other investigators. Nevertheless, it is still attractive to conceive that glomerular C3 receptor sites might be responsible for binding of antigen-antibody-complement complexes and formation of immune-complex deposits, at least on the epimembranous (subepithelial) surface of glomerular capillary walls. Inability to demonstrate this

  19. Molecular Characterization and Expression Analyses of the Complement Component C8α, C8β and C9 Genes in Yellow Catfish (Pelteobagrus fulvidraco) after the Aeromonas hydrophila Challenge.

    PubMed

    Zheng, Huan; Ji, Wei; Zhang, Gui-Rong; Zhang, Xiao-Ting; Shi, Ze-Chao; Wei, Kai-Jian; Yang, Rui-Bin; Gardner, Jonathan P A

    2016-01-01

    The complement components C8α, C8β and C9 have important roles in the innate immune system against invading microorganisms. Partial cDNA sequences of the Pf_C8α, Pf_C8β and Pf_C9 genes (Pf: abbreviation of Pelteobagrus fulvidraco) were cloned from yellow catfish. The Pf_C8α, Pf_C8β and Pf_C9 genes showed the greatest amino acid similarity to C8α (54%) and C8β (62%) of zebrafish and to C9 (52%) of grass carp, respectively. Ontogenetic expression analyses using real-time quantitative PCR suggested that the three genes may play crucial roles during embryonic and early larval development. The mRNA expressions of the three genes were all at the highest levels in liver tissue, and at lower or much lower levels in 16 other tissues, demonstrating that the liver is the primary site for the protein synthesis of Pf_C8α, Pf_C8β and Pf_C9. Injection of Aeromonas hydrophila led to up-regulation of the three genes in the spleen, head kidney, kidney, liver and blood tissues, indicating that the three genes may contribute to the host's defense against invading pathogenic microbes. An increased understanding of the functions of the Pf_C8α, Pf_C8β and Pf_C9 genes in the innate immunity of yellow catfish will help enhance production of this valuable freshwater species. PMID:27005612

  20. Molecular Characterization and Expression Analyses of the Complement Component C8α, C8β and C9 Genes in Yellow Catfish (Pelteobagrus fulvidraco) after the Aeromonas hydrophila Challenge

    PubMed Central

    Zheng, Huan; Ji, Wei; Zhang, Gui-Rong; Zhang, Xiao-Ting; Shi, Ze-Chao; Wei, Kai-Jian; Yang, Rui-Bin; Gardner, Jonathan P. A.

    2016-01-01

    The complement components C8α, C8β and C9 have important roles in the innate immune system against invading microorganisms. Partial cDNA sequences of the Pf_C8α, Pf_C8β and Pf_C9 genes (Pf: abbreviation of Pelteobagrus fulvidraco) were cloned from yellow catfish. The Pf_C8α, Pf_C8β and Pf_C9 genes showed the greatest amino acid similarity to C8α (54%) and C8β (62%) of zebrafish and to C9 (52%) of grass carp, respectively. Ontogenetic expression analyses using real-time quantitative PCR suggested that the three genes may play crucial roles during embryonic and early larval development. The mRNA expressions of the three genes were all at the highest levels in liver tissue, and at lower or much lower levels in 16 other tissues, demonstrating that the liver is the primary site for the protein synthesis of Pf_C8α, Pf_C8β and Pf_C9. Injection of Aeromonas hydrophila led to up-regulation of the three genes in the spleen, head kidney, kidney, liver and blood tissues, indicating that the three genes may contribute to the host’s defense against invading pathogenic microbes. An increased understanding of the functions of the Pf_C8α, Pf_C8β and Pf_C9 genes in the innate immunity of yellow catfish will help enhance production of this valuable freshwater species. PMID:27005612

  1. Alteration of human erythrocyte membrane properties by complement fixation.

    PubMed Central

    Durocher, J R; Gockerman, J P; Conrad, M E

    1975-01-01

    Erythrocyte survival studies of complement-coated radiolabeled erythrocytes have shown rapid removal of these cells from the peripheral blood with a return of these cells into the circulation within a few hours. We studied complement-coated human erythrocytes and measured surface charge and deformability, two parameters believed to be important in erythrocyte survival. Erythrocytes were coated with complement by two in vitro techniques: the addition of (a) low ionic strength sucrose, and (b) IgM cold agglutinins. Erythrocytes obtained from three patients with cold agglutinin disease were used as a source of in vivo complement-coated cells. No difference was found in surface charge as measured by electrophoretic mobility between erythrocytes from normal subjects and complement-coated erythrocytes from any of the three sources. When deformability was measured by filtration through 3-mum polycarbonate sieves, marked decreases in deformability were found in complement-coated erythrocytes. The filtration returned toward control levels by incubating the complement-coated erythrocytes in serum for 1 h and correlated with decreases in immune adherence. Using screen filtration pressure as a measure of deformability, a positive correlation between number of C3 molecules per erythrocyte and decreased deformability was found. C3b appeared responsible for the decreased deformability of the erythrocytes, since conversion of C3b to C3d resulted in a return of deformability toward normal. The data suggested that the sequestration of complement-coated human erythrocytes in the microvasculature can be explained in part by decreased deformability and changes in immune adherence. PMID:1120777

  2. The effect of Tlr4 and/or C3 Deficiency and of Neonatal Gene Therapy on Skeletal Disease in Mucopolysaccharidosis VII mice

    PubMed Central

    Xing, Elizabeth M.; Wu, Susan; Ponder, Katherine P.

    2015-01-01

    Mucopolysaccharidosis (MPS) VII is a lysosomal storage disorder caused by the deficiency of the enzyme β-glucuronidase (Gusb-/-) and results in glycosaminoglycan (GAG) accumulation. Skeletal abnormalities include stunted long bones and bone degeneration. GAGs have been hypothesized to activate toll-like receptor 4 (Tlr4) signaling and the complement pathway, resulting in upregulation of inflammatory cytokines that suppress growth and cause degeneration of bone. Gusb-/- mice were bred with Tlr4- and complement component 3 (C3)-deficient mice, and the skeletal manifestations of the doubly- and triply-deficient mice were compared to those of purebred Gusb-/- mice. Radiographs showed that purebred Gusb-/- mice had shorter tibias and femurs, and wider femurs, compared to normal mice. No improvement was seen in Tlr4, C3, or Tlr4/C3-deficient Gusb-/- mice. The glenoid cavity and humerus were scored on a scale from 0 (normal) to +3 (severely abnormal) for dysplasia and bone irregularities, and the joint space was measured. No improvement was seen in Tlr4, C3, or Tlr4/C3-deficient Gusb-/- mice, and their joint space remained abnormally wide. Gusb-/- mice treated neonatally with an intravenous retroviral vector (RV) had thinner femurs, longer legs, and a narrowed joint space compared with untreated purebred Gusb-/- mice, but no improvement in glenohumeral degeneration. We conclude that Tlr4- and/or C3- deficiency fail to ameliorate skeletal abnormalities, and other pathways may be involved. RV treatment improves some but not all aspects of bone disease. Radiographs may be an efficient method for future evaluation, as they readily show glenohumeral joint abnormalities. PMID:25559179

  3. Identification of a Rare Coding Variant in Complement 3 Associated with Age-related Macular Degeneration

    PubMed Central

    Zhan, Xiaowei; Larson, David E.; Wang, Chaolong; Koboldt, Daniel C.; Sergeev, Yuri V.; Fulton, Robert S.; Fulton, Lucinda L.; Fronick, Catrina C.; Branham, Kari E.; Bragg-Gresham, Jennifer; Jun, Goo; Hu, Youna; Kang, Hyun Min; Liu, Dajiang; Othman, Mohammad; Brooks, Matthew; Ratnapriya, Rinki; Boleda, Alexis; Grassmann, Felix; von Strachwitz, Claudia; Olson, Lana M.; Buitendijk, Gabriëlle H.S.; Hofman, Albert; van Duijn, Cornelia M.; Cipriani, Valentina; Moore, Anthony T.; Shahid, Humma; Jiang, Yingda; Conley, Yvette P.; Morgan, Denise J.; Kim, Ivana K.; Johnson, Matthew P.; Cantsilieris, Stuart; Richardson, Andrea J.; Guymer, Robyn H.; Luo, Hongrong; Ouyang, Hong; Licht, Christoph; Pluthero, Fred G.; Zhang, Mindy M.; Zhang, Kang; Baird, Paul N.; Blangero, John; Klein, Michael L.; Farrer, Lindsay A.; DeAngelis, Margaret M.; Weeks, Daniel E.; Gorin, Michael B.; Yates, John R.W.; Klaver, Caroline C.W.; Pericak-Vance, Margaret A.; Haines, Jonathan L.; Weber, Bernhard H.F.; Wilson, Richard K.; Heckenlively, John R.; Chew, Emily Y.; Stambolian, Dwight; Mardis, Elaine R.; Swaroop, Anand; Abecasis, Goncalo R.

    2013-01-01

    Macular degeneration is a common cause of blindness in the elderly. To identify rare coding variants associated with a large increase in risk of age-related macular degeneration (AMD), we sequenced 2,335 cases and 789 controls in 10 candidate loci (57 genes). To increase power, we augmented our control set with ancestry-matched exome sequenced controls. An analysis of coding variation in 2,268 AMD cases and 2,268 ancestry matched controls revealed two large-effect rare variants; previously described R1210C in the CFH gene (fcase = 0.51%, fcontrol = 0.02%, OR = 23.11), and newly identified K155Q in the C3 gene (fcase = 1.06%, fcontrol = 0.39%, OR = 2.68). The variants suggest decreased inhibition of C3 by Factor H, resulting in increased activation of the alternative complement pathway, as a key component of disease biology. PMID:24036949

  4. Trichinella spiralis Paramyosin Binds Human Complement C1q and Inhibits Classical Complement Activation

    PubMed Central

    Sun, Ran; Zhao, Xi; Wang, Zixia; Yang, Jing; Zhao, Limei; Zhan, Bin; Zhu, Xinping

    2015-01-01

    Background Trichinella spiralis expresses paramyosin (Ts-Pmy) as a defense mechanism. Ts-Pmy is a functional protein with binding activity to human complement C8 and C9 and thus plays a role in evading the attack of the host’s immune system. In the present study, the binding activity of Ts-Pmy to human complement C1q and its ability to inhibit classical complement activation were investigated. Methods and Findings The binding of recombinant and natural Ts-Pmy to human C1q were determined by ELISA, Far Western blotting and immunoprecipitation, respectively. Binding of recombinant Ts-Pmy (rTs-Pmy) to C1q inhibited C1q binding to IgM and consequently inhibited C3 deposition. The lysis of antibody-sensitized erythrocytes (EAs) elicited by the classical complement pathway was also inhibited in the presence of rTs-Pmy. In addition to inhibiting classical complement activation, rTs-Pmy also suppressed C1q binding to THP-1-derived macrophages, thereby reducing C1q-induced macrophages migration. Conclusion Our results suggest that T. spiralis paramyosin plays an important role in immune evasion by interfering with complement activation through binding to C1q in addition to C8 and C9. PMID:26720603

  5. Vimentin mediates uptake of C3 exoenzyme.

    PubMed

    Rohrbeck, Astrid; Schröder, Anke; Hagemann, Sandra; Pich, Andreas; Höltje, Markus; Ahnert-Hilger, Gudrun; Just, Ingo

    2014-01-01

    Clostridium botulinum C3 exoenzyme (C3) selectively inactivates RhoA/B/C GTPases by ADP-ribosylation. Based on this substrate specificity C3 is a well-established tool in cell biology. C3 is taken up by eukaryotic cells although lacking an uptake and translocation domain. Based on different approaches vimentin was identified as membranous C3-interaction partner by mass spectrometry. Vimentin in fact was partly localized at the outer surface of hippocampal HT22 cells and J744A.1 macrophages. Domain analysis identified the rod domain as binding partner of C3. Vimentin was also involved in uptake of C3 as shown by knock down of vimentin in HT22 and J774A.1 cells. The involvement of vimentin in uptake of C3 was further supported by the findings that the vimentin disruptor acrylamide blocked uptake of C3. Vimentin is not only a major organizing element of the intermediate filament network but is also involved in both binding and uptake of C3 exoenzyme. PMID:24967582

  6. Gender-specific modulation of immune system complement gene expression in marine medaka Oryzias melastigma following dietary exposure of BDE-47.

    PubMed

    Ye, Roy R; Lei, Elva N Y; Lam, Michael H W; Chan, Alice K Y; Bo, Jun; van de Merwe, Jason P; Fong, Amy C C; Yang, Michael M S; Lee, J S; Segner, Helmut E; Wong, Chris K C; Wu, Rudolf S S; Au, Doris W T

    2011-08-01

    BDE-47 is one of the most widely found congeners of PBDEs in marine environments. The potential immunomodulatory effects of BDE-47 on fish complement system were studied using the marine medaka Oryzias melastigma as a model fish. Three-month-old O. melastigma were subjected to short-term (5 days) and long-term (21 days) exposure to two concentrations of BDE-47 (low dose at 290 ± 172 ng/day; high dose at 580 ± 344 ng/day) via dietary uptake of BDE-47 encapsulated in Artemia nauplii. Body burdens of BDE-47 and other metabolic products were analyzed in the exposed and control fish. Only a small amount of debrominated product, BDE-28, was detected, while other metabolic products were all under detection limit. Transcriptional expression of six major complement system genes involved in complement activation: C1r/s (classical pathway), MBL-2 (lectin pathway), CFP (alternative pathway), F2 (coagulation pathway), C3 (the central component of complement system), and C9 (cell lysis) were quantified in the liver of marine medaka. Endogenous expression of all six complement system genes was found to be higher in males than in females (p < 0.05). Upon dietary exposure of marine medaka to BDE-47, expression of all six complement genes were downregulated in males at day 5 (or longer), whereas in females, MBl-2, CFP, and F2 mRNAs expression were upregulated, but C3 and C9 remained stable with exposure time and dose. A significant negative relationship was found between BDE-47 body burden and mRNA expression of C1r/s, CFP, and C3 in male fish (r = -0.8576 to -0.9447). The above findings on changes in complement gene expression patterns indicate the complement system may be compromised in male O. melastigma upon dietary exposure to BDE-47. Distinct gender difference in expression of six major complement system genes was evident in marine medaka under resting condition and dietary BDE-47 challenge. The immunomodulatory effects of BDE-47 on transcriptional

  7. A Serine Protease Isolated from the Bristles of the Amazonic Caterpillar, Premolis semirufa, Is a Potent Complement System Activator

    PubMed Central

    Villas Boas, Isadora Maria; Pidde-Queiroz, Giselle; Magnoli, Fabio Carlos; Gonçalves-de-Andrade, Rute M.; van den Berg, Carmen W.; Tambourgi, Denise V.

    2015-01-01

    Background The caterpillar of the moth Premolis semirufa, commonly named pararama, is found in the Brazilian Amazon region. Accidental contact with the caterpillar bristles causes an intense itching sensation, followed by symptoms of an acute inflammation, which last for three to seven days after the first incident. After multiple accidents a chronic inflammatory reaction, called “Pararamose”, characterized by articular synovial membrane thickening with joint deformities common to chronic synovitis, frequently occurs. Although complement mediated inflammation may aid the host defense, inappropriate or excessive activation of the complement system and generation of anaphylatoxins can lead to inflammatory disorder and pathologies. The aim of the present study was to evaluate, in vitro, whether the Premolis semirufa’s bristles extract could interfere with the human complement system. Results The bristles extract was able to inhibit the haemolytic activity of the alternative pathway, as well as the activation of the lectin pathway, but had no effect on the classical pathway, and this inhibition seemed to be caused by activation and consumption of complement components. The extract induced the production of significant amounts of all three anaphylatoxins, C3a, C4a and C5a, promoted direct cleavage of C3, C4 and C5 and induced a significant generation of terminal complement complexes in normal human serum. By using molecular exclusion chromatography, a serine protease of 82 kDa, which activates complement, was isolated from P. semirufa bristles extract. The protease, named here as Ps82, reduced the haemolytic activity of the alternative and classical pathways and inhibited the lectin pathway. In addition, Ps82 induced the cleavage of C3, C4 and C5 and the generation of C3a and C4a in normal human serum and it was capable to cleave human purified C5 and generate C5a. The use of Phenanthroline, metalloprotease inhibitor, in the reactions did not significantly

  8. Streptococcus pneumoniae Phosphoglycerate Kinase Is a Novel Complement Inhibitor Affecting the Membrane Attack Complex Formation*

    PubMed Central

    Blom, Anna M.; Bergmann, Simone; Fulde, Marcus; Riesbeck, Kristian; Agarwal, Vaibhav

    2014-01-01

    The Gram-positive bacterium Streptococcus pneumoniae is a major human pathogen that causes infections ranging from acute otitis media to life-threatening invasive disease. Pneumococci have evolved several strategies to circumvent the host immune response, in particular the complement attack. The pneumococcal glycolytic enzyme phosphoglycerate kinase (PGK) is both secreted and bound to the bacterial surface and simultaneously binds plasminogen and its tissue plasminogen activator tPA. In the present study we demonstrate that PGK has an additional role in modulating the complement attack. PGK interacted with the membrane attack complex (MAC) components C5, C7, and C9, thereby blocking the assembly and membrane insertion of MAC resulting in significant inhibition of the hemolytic activity of human serum. Recombinant PGK interacted in a dose-dependent manner with these terminal pathway proteins, and the interactions were ionic in nature. In addition, PGK inhibited C9 polymerization both in the fluid phase and on the surface of sheep erythrocytes. Interestingly, PGK bound several MAC proteins simultaneously. Although C5 and C7 had partially overlapping binding sites on PGK, C9 did not compete with either one for PGK binding. Moreover, PGK significantly inhibited MAC deposition via both the classical and alternative pathway at the pneumococcal surface. Additionally, upon activation plasmin(ogen) bound to PGK cleaved the central complement protein C3b thereby further modifying the complement attack. In conclusion, our data demonstrate for the first time to our knowledge a novel pneumococcal inhibitor of the terminal complement cascade aiding complement evasion by this important pathogen. PMID:25281746

  9. The indoleamine 2,3-dioxygenase pathway controls complement-dependent enhancement of chemo-radiation therapy against murine glioblastoma

    PubMed Central

    2014-01-01

    Background Indoleamine 2,3-dioxygenase (IDO) is an enzyme with immune-suppressive properties that is commonly exploited by tumors to evade immune destruction. Anti-tumor T cell responses can be initiated in solid tumors, but are immediately suppressed by compensatory upregulation of immunological checkpoints, including IDO. In addition to these known effects on the adaptive immune system, we previously showed widespread, T cell-dependent complement deposition during allogeneic fetal rejection upon maternal treatment with IDO-blockade. We hypothesized that IDO protects glioblastoma from the full effects of chemo-radiation therapy by preventing vascular activation and complement-dependent tumor destruction. Methods To test this hypothesis, we utilized a syngeneic orthotopic glioblastoma model in which GL261 glioblastoma tumor cells were stereotactically implanted into the right frontal lobes of syngeneic mice. These mice were treated with IDO-blocking drugs in combination with chemotherapy and radiation therapy. Results Pharmacologic inhibition of IDO synergized with chemo-radiation therapy to prolong survival in mice bearing intracranial glioblastoma tumors. We now show that pharmacologic or genetic inhibition of IDO allowed chemo-radiation to trigger widespread complement deposition at sites of tumor growth. Chemotherapy treatment alone resulted in collections of perivascular leukocytes within tumors, but no complement deposition. Adding IDO-blockade led to upregulation of VCAM-1 on vascular endothelium within the tumor microenvironment, and further adding radiation in the presence of IDO-blockade led to widespread deposition of complement. Mice genetically deficient in complement component C3 lost all of the synergistic effects of IDO-blockade on chemo-radiation-induced survival. Conclusions Together these findings identify a novel mechanistic link between IDO and complement, and implicate complement as a major downstream effector mechanism for the beneficial

  10. Storage of platelets in earth orbit. Effect of gravity and the formulation of plastic storage containers on platelet IgG and C3.

    PubMed

    Szymanski, I O; Odgren, P R; Teno, R A; Jacobson, M S; Surgenor, D M

    1989-01-01

    We investigated the effects of gravitational force and three different plastic formulations of the storage bags on the quality of stored platelets by measuring the changes in platelet-associated immunoglobulin G (IgG) and two antigenic markers of the third component of human complement (C3), C3d and C3c. Pooled platelets were stored in parallel at microgravity (MG) and on the ground (1 g) using three different plastic polymers: (1) polyvinylchloride (PVC) plasticized with di-2-ethylhexyl phthalate (DEHP); (2) PVC plasticized with trioctyl trimellitate (TOTM), and (3) unplasticized polyolefin (PO). The IgG and C3 were quantified by an automated antiglobulin consumption test in freeze/thaw disrupted platelets (total IgG or C3). The baseline values for platelet associated IgG and C3, measured after 2.5 days of storage at 1 g just prior to the launch, fell within the normal range. Following an additional 6.5 day storage, platelets stored at MG had accumulated significantly less C3d than those stored at 1 g, suggesting that MG storage was beneficial. Specific plastic formulations also exerted a significant effect on the accumulation of these immunoproteins, the effect being particularly pronounced at MG. The smallest increases of IgG and C3 were seen in platelets stored in TOTM and the largest in those stored in DEHP. It is possible that further studies at MG would permit a clear characterization of the effects of other independent storage variables. PMID:2781740

  11. Complement system in dermatological diseases - fire under the skin.

    PubMed

    Panelius, Jaana; Meri, Seppo

    2015-01-01

    The complement system plays a key role in several dermatological diseases. Overactivation, deficiency, or abnormality of the control proteins are often related to a skin disease. Autoimmune mechanisms with autoantibodies and a cytotoxic effect of the complement membrane attack complex on epidermal or vascular cells can cause direct tissue damage and inflammation, e.g., in systemic lupus erythematosus (SLE), phospholipid antibody syndrome, and bullous skin diseases like pemphigoid. By evading complement attack, some microbes like Borrelia spirochetes and staphylococci can persist in the skin and cause prolonged symptoms. In this review, we present the most important skin diseases connected to abnormalities in the function of the complement system. Drugs having an effect on the complement system are also briefly described. On one hand, drugs with free hydroxyl on amino groups (e.g., hydralazine, procainamide) could interact with C4A, C4B, or C3 and cause an SLE-like disease. On the other hand, progress in studies on complement has led to novel anti-complement drugs (recombinant C1-inhibitor and anti-C5 antibody, eculizumab) that could alleviate symptoms in diseases associated with excessive complement activation. The main theme of the manuscript is to show how relevant the complement system is as an immune effector system in contributing to tissue injury and inflammation in a broad range of skin disorders. PMID:25688346

  12. Complement System in Dermatological Diseases – Fire Under the Skin

    PubMed Central

    Panelius, Jaana; Meri, Seppo

    2015-01-01

    The complement system plays a key role in several dermatological diseases. Overactivation, deficiency, or abnormality of the control proteins are often related to a skin disease. Autoimmune mechanisms with autoantibodies and a cytotoxic effect of the complement membrane attack complex on epidermal or vascular cells can cause direct tissue damage and inflammation, e.g., in systemic lupus erythematosus (SLE), phospholipid antibody syndrome, and bullous skin diseases like pemphigoid. By evading complement attack, some microbes like Borrelia spirochetes and staphylococci can persist in the skin and cause prolonged symptoms. In this review, we present the most important skin diseases connected to abnormalities in the function of the complement system. Drugs having an effect on the complement system are also briefly described. On one hand, drugs with free hydroxyl on amino groups (e.g., hydralazine, procainamide) could interact with C4A, C4B, or C3 and cause an SLE-like disease. On the other hand, progress in studies on complement has led to novel anti-complement drugs (recombinant C1-inhibitor and anti-C5 antibody, eculizumab) that could alleviate symptoms in diseases associated with excessive complement activation. The main theme of the manuscript is to show how relevant the complement system is as an immune effector system in contributing to tissue injury and inflammation in a broad range of skin disorders. PMID:25688346

  13. Complement activation in the context of stem cells and tissue repair

    PubMed Central

    Schraufstatter, Ingrid U; Khaldoyanidi, Sophia K; DiScipio, Richard G

    2015-01-01

    The complement pathway is best known for its role in immune surveillance and inflammation. However, its ability of opsonizing and removing not only pathogens, but also necrotic and apoptotic cells, is a phylogenetically ancient means of initiating tissue repair. The means and mechanisms of complement-mediated tissue repair are discussed in this review. There is increasing evidence that complement activation contributes to tissue repair at several levels. These range from the chemo-attraction of stem and progenitor cells to areas of complement activation, to increased survival of various cell types in the presence of split products of complement, and to the production of trophic factors by cells activated by the anaphylatoxins C3a and C5a. This repair aspect of complement biology has not found sufficient appreciation until recently. The following will examine this aspect of complement biology with an emphasis on the anaphylatoxins C3a and C5a. PMID:26435769

  14. A role for natural antibody in the pathogenesis of leprosy: antibody in nonimmune serum mediates C3 fixation to the Mycobacterium leprae surface and hence phagocytosis by human mononuclear phagocytes.

    PubMed Central

    Schlesinger, L S; Horwitz, M A

    1994-01-01

    We have previously determined that complement receptors on human mononuclear phagocytes and complement component C3 in nonimmune serum mediate phagocytosis of the intracellular bacterial pathogen Mycobacterium leprae, the agent of leprosy. We have also determined that C3 fixes selectively to the major surface glycolipid of M. leprae, phenolic glycolipid 1 (PGL-1). In this study, we have explored the role of natural antibody in nonimmune serum in C3 fixation and C1q binding to M. leprae and PGL-1. At serum concentrations within the range at which phagocytosis of M. leprae is maximal, C3 fixation was mediated by both the classical and the alternative complement pathways. At the low end of this serum concentration range (2.5%), C3 fixation was mediated predominantly by the classical pathway. Consistent with a role for both pathways, C3 fixation to M. leprae was enhanced by the addition of either pure C1q to C1q-depleted serum or pure factor B to factor B-depleted serum. C3 fixation to M. leprae was strictly antibody dependent regardless of the serum concentration used. C3 fixation to M. leprae occurred in nonimmune serum but not in agammaglobulinemic serum unless heat-inactivated nonimmune serum or small amounts of pure immunoglobulin G (IgG) or IgM were added. C3 fixation by both the alternative and the classical complement pathways was mediated by antibody, and the antigen-binding portion of the antibody molecule was required. C3, IgG, IgM, and C1q were readily detected on the surface of M. leprae. Consistent with the previously demonstrated exclusive role of the classical complement pathway in C3 fixation to PGL-1, C1q bound to PGL-1 in a dose-dependent fashion; C1q binding was evident in > 1.25% nonimmune serum. C1q binding to PGL-1 was strictly antibody dependent. When PGL-1 was incubated with pure C1q, little or no C1q bound to PGL-1 unless heat-inactivated nonimmune serum or pure IgG or IgM was added. When PGL-1 was incubated in nonimmune serum, C3 bound

  15. Visual display principles for C3I system tasks

    NASA Astrophysics Data System (ADS)

    Howell, William C.; Lane, David M.; Laux, Lila F.; Anderson, Loy A.; Holden, Kritina L.

    1993-06-01

    Modern C3I systems are best described as semi-automated data management and decision systems over which human operators exercise supervisory control. The effectiveness of such systems is heavily dependent on the design for human-computer interaction (HCI), an important aspect of which is the visual display interface. Current Department of Defense policy mandates consideration of such human factors issues at an early stage in the design process. Comprehensive guidelines are available for display design applications after the general system parameters have been specified. Some recommendations are general, others are specific. This report offers a set of design principles at an intermediate (conceptual) level of abstraction as a complement to existing guidelines. The purpose is to synthesize current knowledge of human cognition into a form that will be applicable to the earliest stages of display design ('cognitive' functions being the most salient and critical of those remaining for the operator in advanced C3I systems). The principles are derived from a review of the literatures on human cognition, HCI, and display design, some original research, and liberal interpretation by the authors. They are organized according to operations performed on specific categories of information in possible C3I task configurations.

  16. A complement-microglial axis drives synapse loss during virus-induced memory impairment.

    PubMed

    Vasek, Michael J; Garber, Charise; Dorsey, Denise; Durrant, Douglas M; Bollman, Bryan; Soung, Allison; Yu, Jinsheng; Perez-Torres, Carlos; Frouin, Arnaud; Wilton, Daniel K; Funk, Kristen; DeMasters, Bette K; Jiang, Xiaoping; Bowen, James R; Mennerick, Steven; Robinson, John K; Garbow, Joel R; Tyler, Kenneth L; Suthar, Mehul S; Schmidt, Robert E; Stevens, Beth; Klein, Robyn S

    2016-06-23

    Over 50% of patients who survive neuroinvasive infection with West Nile virus (WNV) exhibit chronic cognitive sequelae. Although thousands of cases of WNV-mediated memory dysfunction accrue annually, the mechanisms responsible for these impairments are unknown. The classical complement cascade, a key component of innate immune pathogen defence, mediates synaptic pruning by microglia during early postnatal development. Here we show that viral infection of adult hippocampal neurons induces complement-mediated elimination of presynaptic terminals in a murine WNV neuroinvasive disease model. Inoculation of WNV-NS5-E218A, a WNV with a mutant NS5(E218A) protein leads to survival rates and cognitive dysfunction that mirror human WNV neuroinvasive disease. WNV-NS5-E218A-recovered mice (recovery defined as survival after acute infection) display impaired spatial learning and persistence of phagocytic microglia without loss of hippocampal neurons or volume. Hippocampi from WNV-NS5-E218A-recovered mice with poor spatial learning show increased expression of genes that drive synaptic remodelling by microglia via complement. C1QA was upregulated and localized to microglia, infected neurons and presynaptic terminals during WNV neuroinvasive disease. Murine and human WNV neuroinvasive disease post-mortem samples exhibit loss of hippocampal CA3 presynaptic terminals, and murine studies revealed microglial engulfment of presynaptic terminals during acute infection and after recovery. Mice with fewer microglia (Il34(-/-) mice with a deficiency in IL-34 production) or deficiency in complement C3 or C3a receptor were protected from WNV-induced synaptic terminal loss. Our study provides a new murine model of WNV-induced spatial memory impairment, and identifies a potential mechanism underlying neurocognitive impairment in patients recovering from WNV neuroinvasive disease. PMID:27337340

  17. A Study on the Humoral and Complement Immune System of Patients with Organic Acidemia.

    PubMed

    Alizadeh Najjarbashi, Faegheh; Mesdaghi, Mehrnaz; Alaei, Mohammadreza; Shakiba, Marjan; Jami, Aliakbar; Ghadimi, Farah

    2015-12-01

    Patients with organic acidemia are prone to different infections, which lead to acidosis episodes. Some studies have evaluated the status of immune system in acidotic phase in these patients, but to the best of our knowledge no study has evaluated the immune system in non-acidotic phase of the disease. In this study, thirty-one patients with organic acidemia were enrolled. For evaluation of humoral immunity, serum IgA, IgG, IgE, IgM, isohemaggltuinin titer, anti tetanus and anti diphtheria IgG were measured. For screening of complement deficiencies, serum C3, C4, and CH50 were assessed. Eleven patients had Maple Syrup Urine Disease (MSUD), 10 had methylmalonic acidemia, 5 had isovaleric acidemia, 4 had glutaric aciduria, and 1 had propionic acidemia. Serum IgM level was less than normal in 2 patients. Serum isohemagglutinin titer was less than 1:8 in 2 other patients. IgA, IgE, and IgG were within normal range for all patients. Anti tetanus and anti diphtheria IgG levels were low in two patients with MSUD. No significant relationship was found between any of the measured parameters and history of recurrent admissions, recurrent infections and the type of their diseases. Five patients had high C3 level, 4 had high C4 level, and 5 had high CH50 percentage. Totally, 10 patients had high complement level, but no remarkable connection was noted between the type of the disease and complement level. Minor insignificant deficiencies in humoral immunity in non-acidotic phase of organic acidemia were found. Some components of complement system showed increase in some patients, which might be due to decreased pH in extracellular fluid. PMID:26725562

  18. Clinical significance of complement deficiencies.

    PubMed

    Pettigrew, H David; Teuber, Suzanne S; Gershwin, M Eric

    2009-09-01

    The complement system is composed of more than 30 serum and membrane-bound proteins, all of which are needed for normal function of complement in innate and adaptive immunity. Historically, deficiencies within the complement system have been suspected when young children have had recurrent and difficult-to-control infections. As our understanding of the complement system has increased, many other diseases have been attributed to deficiencies within the complement system. Generally, complement deficiencies within the classical pathway lead to increased susceptibility to encapsulated bacterial infections as well as a syndrome resembling systemic lupus erythematosus. Complement deficiencies within the mannose-binding lectin pathway generally lead to increased bacterial infections, and deficiencies within the alternative pathway usually lead to an increased frequency of Neisseria infections. However, factor H deficiency can lead to membranoproliferative glomerulonephritis and hemolytic uremic syndrome. Finally, deficiencies within the terminal complement pathway lead to an increased incidence of Neisseria infections. Two other notable complement-associated deficiencies are complement receptor 3 and 4 deficiency, which result from a deficiency of CD18, a disease known as leukocyte adhesion deficiency type 1, and CD59 deficiency, which causes paroxysmal nocturnal hemoglobinuria. Most inherited deficiencies of the complement system are autosomal recessive, but properidin deficiency is X-linked recessive, deficiency of C1 inhibitor is autosomal dominant, and mannose-binding lectin and factor I deficiencies are autosomal co-dominant. The diversity of clinical manifestations of complement deficiencies reflects the complexity of the complement system. PMID:19758139

  19. Vitronectin-binding staphylococci enhance surface-associated complement activation.

    PubMed Central

    Lundberg, F; Lea, T; Ljungh, A

    1997-01-01

    Coagulase-negative staphylococci are well recognized in medical device-associated infections. Complement activation is known to occur at the biomaterial surface, resulting in unspecific inflammation around the biomaterial. The human serum protein vitronectin (Vn), a potent inhibitor of complement activation by formation of an inactive terminal complement complex, adsorbs to biomaterial surfaces in contact with blood. In this report, we discuss the possibility that surface-immobilized Vn inhibits complement activation and the effect of Vn-binding staphylococci on complement activation on surfaces precoated with Vn. The extent of complement activation was measured with a rabbit anti-human C3c antibody and a mouse anti-human C9 antibody, raised against the neoepitope of C9. Our data show that Vn immobilized on a biomaterial surface retains its ability to inhibit complement activation. The additive complement activation-inhibitory effect of Vn on a heparinized surface is very small. In the presence of Vn-binding strain, Staphylococcus hemolyticus SM131, complement activation on a surface precoated with Vn occurred as it did in the absence of Vn precoating. For S. epidermidis 3380, which does not express binding of Vn, complement activation on a Vn-precoated surface was significantly decreased. The results could be repeated on heparinized surfaces. These data suggest that Vn adsorbed to a biomaterial surface may serve to protect against surface-associated complement activation. Furthermore, Vn-binding staphylococcal cells may enhance surface-associated complement activation by blocking the inhibitory effect of preadsorbed Vn. PMID:9038294

  20. 42 CFR 52c.3 - Eligibility.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Eligibility. 52c.3 Section 52c.3 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS MINORITY BIOMEDICAL RESEARCH... institution offering undergraduate, graduate, or health professional degrees, with a traditionally high...

  1. 42 CFR 52c.3 - Eligibility.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Eligibility. 52c.3 Section 52c.3 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES GRANTS MINORITY BIOMEDICAL RESEARCH... institution offering undergraduate, graduate, or health professional degrees, with a traditionally high...

  2. Genetics Home Reference: C3 glomerulopathy

    MedlinePlus

    ... Jones M, Maga T, Katz LM, Zhang Y, Smith RJ. Allelic variants of complement genes associated with ... Frees K, Schnieders MJ, Thomas C, Nester C, Smith RJ. High-Throughput Genetic Testing for Thrombotic Microangiopathies ...