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)

The activation of phagocytes by the lipid A moiety of LPS has been implicated in the pathogenesis of Gram-negative sepsis. While two LPS receptors, CD14 and CD11/CD18, have been associated with cell signaling, details of the LPS signal transduction cascade remain obscure. CD14, which exists as a GPI-anchored and a soluble protein, lacks cytoplasmic-signaling domains, suggesting that an ancillary molecule is required to activate cells. The CD11/CD18 integrins are transmembrane proteins. Like CD14, they are capable of mediating LPS-induced cellular activation when expressed on the surface of hamster fibroblasts Chinese hamster ovary (CHO)-K1. The observation that a cytoplasmic deletion mutant is still capable of activating transfected CHO-K1 argues that CD11/CD18 also utilizes an associated signal transducer. We sought to identify further similarities between the signaling systems utilized by CD14 and CD11/CD18. LPS-binding protein, which transfers LPS to CD14, enhanced both LPS-induced cellular activation and binding of Gram-negative bacteria in CD11/CD18-transfected CHO-K1, thus implying that LPS-binding protein can also transfer LPS to CD11/CD18. When synthetic lipid A analogues were analyzed for their ability to function as LPS agonists, or antagonists, in the CHO transfectants, we found the effects were identical regardless of which LPS receptor was expressed. This supports the hypothesis that a receptor distinct from CD14 and CD11/CD18 is responsible for discriminating between the lipid A of LPS and the LPS antagonists. We propose that this receptor, which is the target of the LPS antagonists, functions as the true signal transducer in LPS-induced cellular activation for both CD14 and CD11/CD18.
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PMID:CD11/CD18 and CD14 share a common lipid A signaling pathway. 982 May 16

Cytokines play a pivotal role in the pathogenesis of septic shock. Proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) stimulate the progression of septic shock whereas the anti-inflammatory cytokine IL-10 has counterregulative potency. The amino acid glycine (GLY) has been shown to protect against endotoxin shock in the rat by inhibiting TNF-alpha production. In the current study we investigated the role of GLY on lipopolysaccharide (LPS) -induced cell surface marker expression, phagocytosis, and cytokine production on purified monocytes from healthy donors. GLY did not modulate the expression of HLA-DR and CD64 on monocytes, whereas CD11b/CD18 expression (P<0.05) and E. coli phagocytosis (P<0.05) decreased significantly. GLY decreased LPS-induced TNF-alpha production (P<0.01) and increased IL-10 expression of purified monocytes. Similarly, in a whole blood assay, GLY reduced TNF-alpha (P<0.0001) and IL-1beta (P<0.0001) synthesis and increased IL-10 expression (P<0.05) in a dose-dependent manner. The inhibitory effects of GLY were neutralized by strychnine, and the production of IL-10 and TNF-alpha was augmented by anti-IL-10 antibodies. Furthermore, GLY decreased the amount of IL-1beta and TNF-alpha-specific mRNA. Our data indicate that GLY has a potential to be used as an additional immunomodulatory tool in the early phase of sepsis and in different pathophysiological situations related to hypoxia and reperfusion.
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PMID:Immunomodulatory effects of glycine on LPS-treated monocytes: reduced TNF-alpha production and accelerated IL-10 expression. 1006 24

We investigated the role of platelet-activating factor (PAF) as a priming signal for cytokine-induced neutrophil chemoattractant (CINC) expression by bronchoalveolar macrophages in acute pancreatitis. Pancreatitis was induced by four intramuscular injections of cerulein (50 micrograms/kg at 1-h intervals) in Wistar rats. The animals were injected intraperitoneally with 10 micrograms/kg of lipopolysaccharide (LPS) as a septic challenge. Pancreatitis rats were treated with a bolus intravenous injection of TCV-309 (3 or 30 micrograms/kg) 30 min before the septic challenge. Intense mononuclear cell infiltration and lung hemorrhage occurred in pancreatitis rats complicated with sepsis but were not seen in pancreatitis rats receiving a bolus TCV-309. Pancreatitis rats treated with TCV-309 had lower serum concentrations of CINC after septic challenge and lower levels of CINC messenger RNA (mRNA) in the lung, as well as fewer pulmonary infiltrates immunoreactive for CINC or Mac-1 (CD11b/CD18). In vitro CINC production in response to LPS by bronchoalveolar macrophages obtained from pancreatitis rats 6 h after the first cerulein injection, immediately before septic challenge, was enhanced but was significantly reduced in a TCV-309-sensitive manner. LPS-stimulated in vitro CINC production by naive bronchoalveolar macrophages was significantly enhanced by pretreatment with PAF. TMB-8 (an inhibitor of calcium release from endoplasmic reticulum) or W7 (calmodulin antagonist) completely abrogated the chemoattractant production by bronchoalveolar macrophages pretreated with PAF after LPS stimulation. Altered intracellular calcium, due to Ca2+ efflux from intracellular stores, may be involved in the "priming" of bronchoalveolar macrophages to release CINC after triggering with LPS during acute cerulein-induced pancreatitis. The PAF antagonist TCV-309 effectively prevented hyperactivity of bronchoalveolar macrophages and pancreatitis-associated lung injury after the septic challenge.
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PMID:Platelet-activating factor antagonist (TCV-309) attenuates the priming effects of bronchoalveolar macrophages in cerulein-induced pancreatitis rats. 1023 40

The cellular pathways of infection utilized by pathogenic enteric bacteria have important implications for their clinical manifestations. Yersinia reaches Peyer's patches via M cells and uses plasmid-encoded factors to resist phagocytic cells. Shigella also translocates via M cells and incapacitates phagocytes, but subsequently re-enters the epithelium basolaterally to elicit an acute inflammatory response. Salmonella has recently been shown to both colonize Peyer's patches via M cells and independently disseminate to extraintestinal sites via CD18-expressing phagocytes. M cell-mediated entry can lead to gastroenteritis and mucosal antibody production, while systemic dissemination can result in septicemia and elicitation of systemic immune responses.
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PMID:Cellular routes of invasion by enteropathogens. 1067 13

The complement system is a multifactorial protein cascade system which is essentially involved in the early unspecific immune response. Its major function is the activation of cellular defense mechanisms, opsonisation of foreign particles and the destruction of target cells. While the impact of the different complement components for bacterial elimination still remains controversial, overwhelming activation of the complement cascade, however, can induce life threatening tissue damage due to the effective cytotoxic properties. In the last years a variety of studies demonstrated beneficial, organ protective effects of complement modulation in models of severe inflammation. Attempts to control the complement system include the application of endogenous complement inhibitors e.g. C1-inhibitor (C1-INH) or the administration of recombinant complement receptors such as the soluble complement receptor 1 (rsCR1). Moreover antibodies against key proteins (C3, C5), against their activation products (C5a) or against complement receptor 3 (CR3, CD18/11b) mediated adhesion of leukocytes to the vascular endothelium, represent effective options of complement modulation. Besides this, insertion of membrane bound human complement regulators (DAF- CD55, MCP- CD46 or CD59) into xenogenic donor organs has proven effectiveness to prevent xenograft rejection. The described interventions protected from severe organ damage in various animal models of sepsis, myocardial and intestinal ischaemia-reperfusion injury, ARDS, nephritis, and xenograft rejection. With respect to recent clinical data, complement inhibition could represent a useful therapeutic strategy to control overwhelming inflammation. Own experiments demonstrated protective effects of complement modulation with C1 INH and rsCR1 in a model of complement induced pulmonary injury. With respect to sufficient host defense, however, the use of complement inhibitors must be considered carefully.
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PMID:[The complement system: an old story or target of new therapeutic approaches?]. 1083 72

We hypothesized that anti-CD18 monoclonal antibody, R15.7, a murine IgG(1) antibody which blocks leukocyte-endothelial cell adherence, might ameliorate the cardiopulmonary manifestations of sepsis secondary to group B streptococci (GBS). Twenty-six anesthetized, mechanically ventilated newborn piglets received a continuous infusion of GBS (7.5 x 10(9) cfu/kg/min) and were randomly assigned to a treatment group receiving R15.7 (1 mg/kg i.v.) 15 min prior to GBS infusion or to a control group. Cardiopulmonary measurements, arterial blood gases and peripheral blood leukocytes were obtained over 120 min of R15.7 infusion. GBS infusion caused significant increases in pulmonary artery and systemic arterial blood (Psa) pressures, pulmonary vascular (PVR) and systemic vascular (SVR) resistances, and PVR/SVR ratio with decreases in cardiac output and stroke volume. R15.7-treated piglets maintained significantly higher Psa (p < 0.003), dynamic lung compliance (p < 0.04), PaO2 and pH (p < 0.05), and lower total lung resistance (p < 0.01) and PaCO2 (p < 0.04). A longer median survival time was observed in the treatment group (p < 0.01). These data suggest that administration of a CD18-blocking agent prolongs survival in a young animal model of GBS sepsis, possibly secondary to improved tissue perfusion, lung mechanics and acid-base status.
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PMID:Effects of anti-CD18 monoclonal antibody, R15.7, on the cardiopulmonary manifestations of group B streptococcal sepsis in piglets. 1097 Oct 5

Recent advances suggest that toll-like receptors, various cytokines, cicosanoids, free radicals and macrophage migration inhibitory factor (MIF) play an important role in the pathobiology of septicemia and septic shock. Anti-MIF antibodies can decrease the plasma concentrations of tumor necrosis factor (TNF), lower bacterial circulating counts and enhance survival of animals with septicemia and septic shock. Monocyte expression of MHC-class II antigens, neutrophil expression of the integrin CD11b/CD18 and neutrophil activation can be related to the development of, and/or recovery from, post-operative sepsis. Thus, biological variations in the response of an individual to a given stimulus, appears to determine his/her ability or inability to develop and also recover from sepsis and septic shock. This suggests that it may be possible to predict the development of septicemia and septic shock in a given individual and take appropriate action both to prevent and treat them adequately.
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PMID:Critical advances in septicemia and septic shock. 1109 8

Mice deficient in CD18, which lack all four CD11 integrins, have leukocytosis and increased susceptibility to bacterial infection. To determine the effect of deficiencies in LFA-1 (CD11a/CD18) or Mac-1 (CD11b/CD18) on host defense against systemic bacterial infection, knockout mice were inoculated i.p. with Streptococcus pneumoniae. Increased mortality occurred in both LFA-1(-/-) (15 of 17 vs 13 of 35 in wild type (WT), p < 0.01) and Mac-1(-/-) (17 of 34 vs 6 of 25, p < 0.01) mice. All deaths in LFA-1(-/-) mice occurred after 72 h, whereas most deaths in Mac-1(-/-) mice occurred within 24-48 h. At 24 h, 21 of 27 Mac-1(-/-) mice were bacteremic, vs 15 of 25 WT (p = 0.05); no difference was observed between LFA-1(-/-) and WT. Increased bacteria were recovered from Mac-1(-/-) spleens at 2 h (p = 0.03) and 6 h (p = 0.002) and from livers (p = 0.001) by 6 h. No difference was observed at 2 h in LFA-1(-/-) mice, but by 6 h increased bacteria were recovered from spleens (p = 0.008) and livers (p = 0.04). Baseline and peak leukocyte counts were similar between Mac-1(-/-) and WT, but elevated in LFA-1(-/-). At 8 h, peritoneal neutrophils were increased in Mac-1(-/-), but not significantly different in LFA-1(-/-). Histopathologically, at 24 h Mac-1(-/-) animals had bacteremia and lymphoid depletion, consistent with sepsis. LFA-1(-/-) mice had increased incidence of otitis media and meningitis/encephalitis vs WT at 72 and 96 h. Both Mac-1 and LFA-1 play important but distinct roles in host defense to S. pneumoniae.
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PMID:The differential roles of LFA-1 and Mac-1 in host defense against systemic infection with Streptococcus pneumoniae. 1139 Apr 87

Modulins represent microbial products that stimulate cytokine production in host cells. The modulins responsible for gram-positive sepsis remain poorly understood. Staphylococci release a factor (or factors) that activates nuclear factor-kappa B and stimulates cytokine production in cells of macrophage lineage. This factor, termed phenol-soluble modulin (PSM), has been recently isolated from culture supernatant of Staphylococcus epidermidis. We examined the effects of PSM on proinflammatory properties of human neutrophils and monocytes in vitro. PSM activated the respiratory (oxidative) burst in neutrophils and primed neutrophils for enhanced respiratory burst activity in response to formyl-methionyl-leucyl-phenylalanine. PSM also stimulated neutrophil degranulation as reflected by increased surface expression of CD11b and CD18, which was accompanied by rapid shedding of L-selectin. Spontaneous apoptosis of both neutrophils and monocytes was inhibited by PSM. Furthermore, PSM also functioned as a chemoattractant factor for both neutrophils and monocytes. Thus, the proinflammatory properties of PSM resemble those of both lipopolysaccharide and bacterial chemotactic peptides. These findings suggest that PSM may play a role in the pathogenesis and systemic manifestations of sepsis caused by staphylococci.
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PMID:Stimulation of human neutrophils and monocytes by staphylococcal phenol-soluble modulin. 1143 91

The in vivo contributions of CD18 integrin-dependent and -independent mechanisms in mediating the increases in lung neutrophil (polymorphonuclear leukocyte; PMN) sequestration and microvascular permeability are not well understood. We determined the time course of these responses to Gram-negative sepsis in the mouse lung and addressed the specific contributions of CD18 integrins and ICAM-1. PMN sequestration in the lung was assessed by morphometric analysis, and transalveolar PMN migration was assessed by bronchoalveolar lavage. Lung tissue PMN number increased by 6-fold within 1 h after i.p. Escherichia coli challenge; this value peaked at 3 h (7-fold above control) and decreased at 12 h (3.5-fold above control). PMN migration into the airspace was delayed; the value peaked at 6 h and remained elevated up to 12 h. Saturating concentrations of anti-CD18 and anti-ICAM-1 mAbs reduced lung tissue PMN sequestration and migration; however, peak responses at 3 and 6 h were inhibited by 40%, indicating that only a small component of PMN sequestration and migration was CD18 dependent at these times. In contrast to the time-dependent decreased role of CD18 integrins in mediating PMN sequestration and migration, CD18 and ICAM-1 blockade prevented the increase in lung microvascular permeability and edema formation at all times after E. coli challenge. Thus, Gram-negative sepsis engages CD18/ICAM-1-independent mechanisms capable of the time-dependent amplification of lung PMN sequestration and migration. The increased pulmonary microvascular permeability induced by E. coli is solely the result of engagement of CD18 integrins even when PMN accumulation and migration responses are significantly CD18 independent.
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PMID:Differential role of CD18 integrins in mediating lung neutrophil sequestration and increased microvascular permeability induced by Escherichia coli in mice. 1150 37


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