Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036690 (sepsis)
 59,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

C5a-C5aR signaling plays an essential role in innate immunity of neutrophils. However, excessive interaction of C5a-C5aR results in harmful effects in these cells. In sepsis, robust generation of C5a occurs; blockade of either C5a or C5aR greatly improves survival in experimental sepsis following cecal ligation and puncture (CLP). The beneficial effects derived from C5a-C5aR interaction are associated with preservation of neutrophil innate immune functions (chemotaxis, phagocytosis, respiratory burst), attenuation of the inflammatory reaction, amelioration of coagulopathy, alteration in adhesion molecule expression, and modulation of apoptosis. Following CLP, C5aR expression is significantly elevated in organs, perhaps setting the stage for C5a-induced organ dysfunction. In contrast, C5aR content on neutrophils drops significantly at early stages of sepsis and progressively increases at later time points. Re-expression of C5aR on neutrophils during sepsis appears to be associated with the functional recovery of neutrophil innate immune functions. Following CLP, there is a positive correlation between C5aR content on blood neutrophils and survival of individual animals; high levels of C5aR on neutrophils are associated with survival, whereas low levels of C5aR on neutrophils predict mortality. These data suggest that in sepsis C5a-C5aR signaling is excessive, resulting in paralysis of neutrophil function. Interception of either C5a or C5aR dramatically improves survival during experimental sepsis.
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PMID:Role of C5a-C5aR interaction in sepsis. 1467 76

Experimental sepsis in rodents occurring after cecal ligation/puncture (CLP) is associated with excessive complement activation and a systemic inflammatory response. The proinflammatory mediator IL-6 has recently been shown to be an important inducer of the C5a receptor (C5aR) during sepsis. We now provide evidence that serum IL-6 production during sepsis in rats was reduced in neutrophil-depleted animals and that absence of C5aR in mice as well as antibody-blockade of C5a in rats significantly reduced serum levels of IL-6 during sepsis. Lipopolysaccharide (LPS)-induced production in vitro of IL-6 by neutrophils was significantly enhanced in the co-presence of C5a, likely due to transcriptional up-regulation of IL-6. Production of IL-6 in neutrophils by LPS was NF-kappaB dependent (but not on the presence of p50) and dependent on phosphorylation of p38-mitogen activated protein kinase (MAPK) as well as p44/p42 MAPK (ERK1/2) but not on phosphorylation of c-Jun N-terminal kinases (JNK1/2). C5a stimulation of neutrophils elicited a rapid phosphorylation of ERK1/2 and p38 MAPK. Accordingly, we suggest that induction of IL-6 after CLP is neutrophil and C5a/C5aR dependent, likely due to the ability of C5a to cause activation of ERK1/2 and p38 MAPK signaling pathways.
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PMID:Regulatory role of C5a in LPS-induced IL-6 production by neutrophils during sepsis. 1468 99

An important virulence factor of the pathogenic fungus Cryptococcus neoformans is its polysaccharide capsule. The capsular polysaccharides glucuronoxylomannan (GXM), galactoxylomannan (GalXM) and the mannoproteins (MPs) display various immunomodulatory effects on the host response, such as the inhibition of phagocytosis, suppression of T-cell mediated immunity, and induction of immunogenic tolerance. Moreover, these capsular polysaccharides are able to interfere with the migration of phagocytes despite adequate stimulation of chemokine production and their concerted action accounts for the mild inflammatory response often observed in cryptococcosis. Different mechanisms contribute to this phenomenon. First, cryptococcal polysaccharides impair leukocyte migration towards chemoattractants. A combination of the intrinsic chemoattracting properties of circulating polysaccharides and the ability to induce cross-desensitization of chemokine receptors prevents leukocytes from leaving the bloodstream and migrating towards inflammatory site. Polysaccharide-induced repressive effects on the C5a receptor expression on neutrophils may also add to this impaired chemokinesis. Second, polysaccharides interfere with leukocyte adhesion to and migration through the endothelium. Both GXM and MP-4 induce L-selectin shedding from the surface of leukocytes; hence, interference with leukocyte rolling on the endothelium can be expected. GXM also interferes with the subsequent process of firm leukocyte adhesion to the endothelium in vitro. Thirdly, capsular polysaccharides enhance the production of anti-inflammatory interleukin-10 (IL-10) and induce tumor necrosis factor-alpha (TNFalpha) receptor loss from the surface of neutrophils. The capacity to reduce neutrophil influx makes cryptococcal polysaccharides interesting compounds to study in clinical models of inflammation (i.e.; sepsis, auto-immune disorders) in which leukocyte influx can be potentially damaging to host tissues.
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PMID:Effects of the capsular polysaccharides of Cryptococcus neoformans on phagocyte migration and inflammatory mediators. 1475 21

There is evidence that C5a and macrophage migration inhibitory factor (MIF) both play important roles in experimental sepsis. Humans with sepsis also show elevated levels of both mediators in the blood. Regulation of MIF during sepsis is poorly understood. We now demonstrate that neutrophil depletion greatly reduced serum MIF levels in rats and mice during the onset of sepsis after cecal ligation and puncture. In vitro, C5a induced MIF release from rat and mouse neutrophils. In vivo blockade of C5aR or absence of C5aR led to significantly reduced MIF generation during the onset of sepsis. C5a-induced release in vitro of MIF from neutrophils appeared to be due to up-regulation of MIF in cytoplasmic granules of neutrophils via activation of the protein kinase B signaling pathway together with involvement of PI3K. Our data suggest that C5a plays a role in enhancing MIF release from neutrophils in vitro and during sepsis. These findings represent a previously unrecognized function of C5a and neutrophils in the appearance of MIF in sepsis.
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PMID:Regulatory role of C5a on macrophage migration inhibitory factor release from neutrophils. 1524 Jul 30

Sepsis is associated with extensive complement activation, compromising innate immune defenses, especially in neutrophils (PMN). Recently, a second C5a receptor (C5L2) was detected on PMN without evidence of intracellular signaling. The current study was designed to determine changes in C5L2 in blood PMN during sepsis. In vitro exposure of PMN to C5a, but not to fMLP, led to reduced content of C5L2. Following cecal ligation and puncture-induced sepsis in rats, PMN demonstrated a time-dependent decrease in C5L2. In vivo blockade of C5a during experimental sepsis resulted in preservation of C5L2. Similarly, PMN from patients with progressive sepsis showed significantly reduced C5L2 expression (n = 26), which was virtually abolished in patients who developed multiorgan failure (n = 10). In contrast, sepsis survivors exhibited retention of C5L2 (n = 12/13). The data suggest that C5L2 on PMN diminishes during sepsis due to systemic generation of C5a, which is associated with a poor prognosis.
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PMID:Changes in the novel orphan, C5a receptor (C5L2), during experimental sepsis and sepsis in humans. 1563 36

Real-time reverse transcriptase polymerase chain reaction (RT rtPCR) was used to quantify the pattern of inflammatory mediator mRNA expression in circulating leukocytes from adult patients diagnosed with severe sepsis. We analysed 29 blood samples from 26 severely septic patients with different septic sources and eight samples from eight healthy adult volunteers. RT rtPCR was used to quantify mRNA expression of 21 different inflammatory mediators in peripheral leukocytes. The median variability in gene expression in the sepsis patients was 10.5 times greater than the variability of the healthy comparison group. We found a significant change in the regulation for the following genes: C5aR (20-fold, P < 0.001), IL-8 (29-fold, P < 0.001), MMP9 (72-fold, P < 0.001), HSP70 (2.4-fold, P = 0.02), and RIP2 (1.8-fold, P < 0.04) were up-regulated. Conversely the median expression of IFNgamma, and IL-6 were zero (P < 0.001), and mtHSP (0.4-fold, P = 0.02) was significantly down-regulated. Using linear discriminant analysis, IFNgamma, IL-12, and TLR4 were correlated to a negative outcome. Different septic sources (peritonitis, burn, pneumonia and musculo-skeletal infections) resulted in significantly different mRNA patterns. The RT rtPCR is a useful tool to monitor the immune response in septic patients. We found a very high variability in inflammatory mediator expression among septic patients compared to healthy volunteers. This suggests that any future immune-modulatory therapy may need to be individualized to the patient's requirements as monitored by RT rtPCR. Different sources of sepsis may result in markedly different activation patterns.
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PMID:The use of real time rtPCR to quantify inflammatory mediator expression in leukocytes from patients with severe sepsis. 1564 82

During experimental sepsis in rodents after cecal ligation and puncture (CLP), excessive C5a is generated, leading to interactions with C5aR, loss of innate immune functions of neutrophils, and lethality. In the current study, we have analyzed the expression of the second C5a receptor C5L2, the putative "default" or nonsignaling receptor for C5a. Rat C5L2 was cloned, and antibody was developed to C5L2 protein. After CLP, blood neutrophils showed a reduction in C5aR followed by its restoration, while C5L2 levels gradually increased, accompanied by the appearance of mRNA for C5L2. mRNA for C5L2 increased in lung and liver during CLP. Substantially increased C5L2 protein (defined by binding of 125I-anti-C5L2 IgG) occurred in lung, liver, heart, and kidney after CLP. With the use of serum IL-6 as a marker for sepsis, infusion of anti-C5aR dramatically reduced serum IL-6 levels, while anti-C5L2 caused a nearly fourfold increase in IL-6 when compared with CLP controls treated with normal IgG. When normal blood neutrophils were stimulated in vitro with LPS and C5a, the antibodies had similar effects on release of IL-6. These data provide the first evidence for a role for C5L2 in balancing the biological responses to C5a.
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PMID:Evidence for a functional role of the second C5a receptor C5L2. 1578 21

C5L2 is an enigmatic serpentine receptor that is co-expressed with the C5a receptor on many cells including polymorphonuclear neutrophils. The apparent absence of coupling of C5L2 with G proteins suggests that this receptor may modulate the biological activity of C5a, perhaps by acting as a decoy receptor. Alternatively, C5L2 may affect C5a function through formation of a heteromeric complex with the C5aR, or it may utilize a G protein-independent signaling pathway. Here we show that in mice bearing a targeted deletion of C5L2, the biological activity of C5a/C5a(desArg) is enhanced both in vivo and in vitro. The biological role of C5L2 thus appears to be limiting to the pro-inflammatory response to the anaphylatoxin. Accordingly, up-regulation of C5L2 may be of benefit in inflammatory states driven by C5a, including sepsis, asthma, cystic fibrosis, and chronic obstructive lung disease.
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PMID:An anti-inflammatory function for the complement anaphylatoxin C5a-binding protein, C5L2. 1620 43

Defective cardiac function during sepsis has been referred to as "cardiomyopathy of sepsis." It is known that sepsis leads to intensive activation of the complement system. In the current study, cardiac function and cardiomyocyte contractility have been evaluated in rats after cecal ligation and puncture (CLP). Significant reductions in left ventricular pressures occurred in vivo and in cardiomyocyte contractility in vitro. These defects were prevented in CLP rats given blocking antibody to C5a. Both mRNA and protein for the C5a receptor (C5aR) were constitutively expressed on cardiomyocytes; both increased as a function of time after CLP. In vitro addition of recombinant rat C5a induced dramatic contractile dysfunction in both sham and CLP cardiomyocytes, but to a consistently greater degree in cells from CLP animals. These data suggest that CLP induces C5aR on cardiomyocytes and that in vivo generation of C5a causes C5a-C5aR interaction, causing dysfunction of cardiomyocytes, resulting in compromise of cardiac performance.
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PMID:An essential role for complement C5a in the pathogenesis of septic cardiac dysfunction. 1638 May 9

Treatments targeting complement receptors have been demonstrated to improve outcome in experimental sepsis. The regulation of the complement receptors in sepsis is not clear. Lipopolysaccharide (LPS) stimulation of granulocytes ex vivo has been shown to reduce C5a receptor (CD88) expression and to increase CD35 and CD11b/CD18 expressions in whole blood but not on isolated cells, indicating an indirect effect mediated via factors in the blood. With the aim to study whether these effects could be attributed to C5a, tumour necrosis factor (TNF)-alpha and interleukin (IL)-8, whole blood or isolated granulocytes and monocytes from healthy individuals were investigated. After incubation with C5a in a dose range of 1 x 10(-9)-1 x 10(-7) mol/l, and TNF-alpha and IL-8 at doses of 1-100 ng/ml, the expressions of the complement receptors CD88, CD35, CD11b/CD18 were analysed by flow cytometry. Incubation with C5a reduced granulocyte CD88 expression by 44+/-6.9% and 82+/-4.2%, whereas monocyte CD88 expression decreased by 21+/-4.0 and 30+/-17% (whole blood and isolated cells). IL-8 and TNF-alpha incubation of granulocytes induced similar results. Granulocyte CD35 expression was significantly increased by 367, 175 and 336% by C5a, TNF-alpha, IL-8, respectively; CD11b expression was similarly increased. Consistent with findings in septic patients and after LPS incubation, it is concluded that all stimuli reduced granulocyte CD88 expression, whereas CD35 and CD11b were increased.
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PMID:C5a, interleukin-8 and tumour necrosis factor-alpha-induced changes in granulocyte and monocyte expression of complement receptors in whole blood and on isolated leukocytes. 1649 74


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