Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0243026 (sepsis)
52,417 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sepsis is a systemic inflammatory response to a blood-borne infection that is associated with an extremely high rate of morbidity and mortality. The present article reviews our recent studies involving the role of cyclooxygenase (COX)-2 in host responses to bacterial endotoxemia and its role in the regulation of nitric oxide synthase (NOS)2 and heme oxygenase (HO)-1. COX-2-deficient (-/-) mice display a blunted and delayed induction of the cytokine-inducible genes NOS2 and HO-1 after administration of Escherichia coli lipopolysaccharide (LPS or endotoxin). Translocation and activation of transcription factors important for signaling events during an inflammatory response, such as nuclear factor-kappaB and activating protein-1, are also reduced. In addition, COX-2(-/-) mice have reduced leukocyte infiltration into critical organs (kidneys and lungs) after LPS administration. Interestingly, the absence of COX-2 does not alter the LPS induction of several proinflammatory cytokines in tissue macrophages, but induction of the antiinflammatory cytokine interleukin-10 is exaggerated. After LPS administration, 50% of wild-type (+/+) mice die; however, COX-2(-/-) mice display a dramatic improvement in survival during endotoxemia. Taken together, our findings suggest that COX-2(-/-) mice are resistant to many of the detrimental consequences of endotoxemia.
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PMID:Alteration in heme oxygenase-1 and nitric oxide synthase-2 gene expression during endotoxemia in cyclooxygenase-2-deficient mice. 1534 45

Prostacyclin (PGI(2)) has beneficial cytoprotective properties, is a potent inhibitor of platelet aggregation and has been reported to improve microcirculatory blood flow during sepsis. The formation of PGI(2) in response to proinflammatory cytokines is catalysed by the inducible cyclooxygenase (COX) isoform COX-2. Recombinant human activated protein C (rhAPC, drotrecogin alfa (activated)) was shown to have multiple biological activities in vitro and to promote resolution of organ dysfunction in septic patients. Whether rhAPC exerts its beneficial effects by modulating prostanoid generation is unknown up to now. It was therefore the aim of the study to examine the in vitro effect of rhAPC on COX-2-mRNA-expression and PGI(2) release from human umbilical vein endothelial cells (HUVEC). We found that rhAPC, at supra-therapeutical concentrations (500 ng/ml-20 microg/ml), upregulated the amount of COX-2-mRNA in HUVEC at t=3-9 h and caused a time- and dose-dependent release of 6-keto PGF(1 alpha), the stable hydrolysis product of prostacyclin. RhAPC further increased the stimulating effect of tumor necrosis factor-alpha (TNF-alpha) and thrombin on COX-2-mRNA-levels. Transcript levels of cyclooxygenase-1 (COX-1) and prostaglandin 12 synthase, however, were unaffected by the stimulation with rhAPC or thrombin. The upregulatory effect on COX2-mRNA levels was specific for rhAPC since the zymogen protein C in equimolar concentrations had no effect on COX-2-mRNA-levels or 6-keto PGF(1 alpha)-release. Western Blot analysis revealed an increase of COX-2-protein content in HUVEC after treatment with rhAPC. As shown by experiments using monoclonal antibodies against the thrombin receptor PAR-1 (mAb=ATAP2) and against the endothelial protein C receptor (EPCR; mAb=RCR-252), the effect of rhAPC on COX-2-mRNA upregulation was mediated by binding to the EPCR-receptor and signaling via PAR-1. These results demonstrate that induction of COX-2-expression is an important response of HUVEC to stimulation with rhAPC and may represent a new molecular mechanism, by which rhAPC promotes upregulation of prostanoid production in human endothelium.
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PMID:Recombinant human activated protein C upregulates cyclooxygenase-2 expression in endothelial cells via binding to endothelial cell protein C receptor and activation of protease-activated receptor-1. 1584 23

Bacterial endotoxin produces sepsis associated with alterations in body temperature (fever or hypothermia). The intraperitoneal administration of bacterial endotoxin, lipopolysaccharide (LPS; 50 microg/mouse) led to a decrease in colonic temperature starting 1 hr after the injection. The hypothermic effect was accompanied by a significant increase in hypothalamic leukotriene B4 (LTB4) and prostaglandin E2 (PGE2) levels. 5-lipoxygenase inhibitor, zileuton (200 and 400 mg/kg, po) administered 30 min before LPS challenge significantly prevented hypothermia. However, non-selective cyclooxygenase inhibitor, indomethacin (10, 20 mg/kg, po) did not reverse the hypothermic response. Further, pretreatment of mice with zileuton prevented LPS-stimulated increase in hypothalamic LTB4 levels and caused a relatively small increase in PGE2 levels. Indomethacin had no effect on LTB4 levels but it reduced PGE2 levels. These results suggest a possible involvement of leukotrienes in LPS-induced hypothermia and the potential protective role of 5-lipoxygenase inhibitors in endotoxemia.
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PMID:Effect of 5-lipoxygenase inhibitor against lipopolysaccharide-induced hypothermia in mice. 1635 26

Platelet-activating factor (PAF) is a potent lipid mediator that has been implicated in asthma, sepsis, acute lung injury and ischemia/reperfusion injury. Its actions in the lungs include vasoconstriction, bronchoconstriction, and edema formation. Despite the fact that PAF exerts these actions within minutes, they are mediated by other lipid mediators, in particular eicosanoids generated by cyclooxygenase and lipoxygenase enzymes and sphingolipids generated by acid sphingomyelinase.We will discuss the mechanisms of the PAF-induced pressor responses that are triggered by thromboxane A(2) and leukotrienes, as well the PAF-induced increase in vascular permeability that is mediated by prostaglandin E(2) (PGE(2)) and ceramide.
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PMID:Mechanisms of platelet-activating factor (PAF)-mediated responses in the lung. 1641 1

The aim of this study was to determine if cyclooxygenase (COX) inhibitors influence immune cell distribution in the small intestinal mucosa and mesenteric lymph nodes (MLNs), the grade of mucosal damage, and the rate of apoptosis in septic rats. The effects induced by a selective COX-2 inhibitor (SC-236) were compared with those of a nonselective COX-1 and -2 inhibitor (indomethacin). Cecal ligation and puncture (CLP), CLP + SC-236 p.o, and CLP + indomethacin p.o, were evaluated. Animals were harvested 6 and 24 h after CLP, respectively. The concentration of proinflammatory cytokines was higher in ascitic fluid than in blood. CLP + SC-236 attenuated IL-6 in plasma and in ascitic fluid and CLP + indomethacin augmented TNF-alpha in ascitic fluid compared with CLP at 6 h. CLP + SC-236 gave a lesser degree of mucosal damage compared with CLP alone or with indomethacin at 6 and 24 h (P < 0.05). Untreated CLP had significant reductions in the number of T lymphocytes in the villi and increases of macrophages in the mucosa and MLNs compared with controls (P < 0.05). CLP + indomethacin decreased T lymphocytes in the villi and MLNs. CLP caused an enhanced apoptosis in the mucosa compared with controls (P < 0.05), pretreatment with COX inhibitors did not significantly change this. Both COX inhibitors enhanced apoptosis in MLNs and attenuated the increase of macrophages in mucosa and MLNs (P < 0.05). It is proposed that the increased apoptosis and the decrease in T cells in the mucosa may be causally related. Apoptosis of lymphocytes may impair the immunologic defense in sepsis. Furthermore, loss of intestinal epithelial cells may compromise bowel wall integrity and facilitate translocation.
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PMID:Influence of cyclooxygenase inhibitors on gut immune cell distribution and apoptosis rate in experimental sepsis. 1652 53

Sepsis induced by exposure to lipopolysaccharide (LPS) can be life-threatening and lead to multiple-organ dysfunction. Sepsis-associated cardiac dysfunction is a primary cause of mortality. The response of isolated cardiac myocytes to LPS exposure is poorly understood. Cultured neonatal rat ventricular cardiomyocytes were used to evaluate the response to LPS exposure. Other authors have reported that LPS exposure at doses sufficient to induce tumor necrosis factor alpha (TNF-alpha) production and apoptosis in adult cardiomyocytes do not induce apoptosis in neonatal cardiomyocytes. We therefore hypothesized that neonatal cardiomyocytes have innate protective mechanisms that protect from septic damage. Cultured neonatal rat ventricular cardiomyocytes were stimulated by exposure to LPS for varying lengths of time. NFkappaB signaling pathways, TNF-alpha production, and Akt activation were monitored. We also assessed the induction of apoptosis in these cells by monitoring caspase-3 activity. LPS rapidly stimulates nuclear translocation of NFkappaB and Akt activation. TNF-alpha production is also stimulated. However, high doses of LPS are unable to induce apoptosis in these cells, and protection is not a function of Akt activation. LPS treatment also stimulated the levels of cyclooxygenase-2 and the production of downstream metabolites, specifically PGE2 and 15deoxyDelta12-14PGJ2 (15dPGJ2). Specific inhibition of cyclooxygenase-2 activity induced apoptosis in the presence of LPS, whereas direct exposure to 15dPGJ2 at pharmacological levels induced apoptosis. Neonatal rat ventricular cardiomyocytes have innate protective mechanisms that prevent apoptotic cell death after LPS exposure. Metabolic products of arachidonic acid metabolized by the cyclooxygenase pathway can be potentially apoptotic or antiapoptotic. The balance of these products within these cells may define the cellular response to LPS exposure.
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PMID:The response of neonatal rat ventricular myocytes to lipopolysaccharide-induced stress. 1668 21

Polymicrobial sepsis induces the suppression of macrophage function as determined by a reduction of pro-inflammatory cytokine production upon re-exposure to lipopolysaccharide (LPS) in vitro. Here, we examined whether macrophages were refractory to only LPS or if they were unable to respond to other stimuli such as CD40 ligand (CD40L). Monocytic cells exposed in vitro to LPS showed a dose-dependent reduction of their ability to produce interleukin-12 and tumour necrosis factor-alpha upon subsequent CD40L stimulation, as compared to cells stimulated with CD40L alone. Similarly, LPS interfered with the up-regulation of CD40, CD80 and CD86 induced by CD40L in monocytic cells. The effect of LPS on the response of monocytes to CD40L was similar whether these cells were directly exposed to LPS or cocultured with LPS-pretreated cells, indicating that soluble factors released by LPS stimulation could mediate tolerance to CD40L. We also show that the functional alterations induced by LPS in monocytes can be reversed by indomethacin, thus suggesting a role for inducible cyclooxygenase in mediating the LPS-induced hyporesponsive state of monocytes to CD40L. In conclusion, we propose that in vitro CD40L tolerance may be an appropriate model of monocyte alteration observed during septic immunosuppression and may help in the development of novel therapeutic strategies.
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PMID:Lipopolysaccharide desensitizes monocytes-macrophages to CD40 ligand stimulation. 1760 91

Sepsis-related acute kidney injury (AKI) is the leading cause of AKI in intensive care units. Endotoxin is a primary initiator of inflammatory and hemodynamic consequences of sepsis and is associated with experimental AKI. The present study was undertaken to further examine the role of the endothelium, specifically prostacyclin (PGI(2)), in the pathogenesis of endotoxemia-related AKI. A low dose of endotoxin (LPS, 1 mg/kg) in wild-type (WT) mice was associated with stable glomerular filtration rate (GFR) (164.0 +/- 16.7 vs. 173.3 +/- 6.7 microl/min, P = not significant) as urinary excretion of 6-keto-PGF(1alpha), the major metabolite of PGI(2), increased. When cyclooxygenase inhibition with indomethacin abolished this rise in 6-keto-PGF(1alpha), the same low dose of LPS significantly decreased GFR (110.7 +/- 12.1 vs. 173.3 +/- 6.7 microl/min, P < 0.05). The same dose of indomethacin did not alter GFR in WT mice. To further study the role of PGI(2) in endotoxemia, renal-specific PGI synthase (PGIs) transgenic (Tg) mice were developed that had increased PGIs expression only in the kidney and increased urinary 6-keto-PGF(1alpha). These Tg mice, however, demonstrated endotoxemia-related AKI with low-dose LPS (1 mg/kg) (GFR: 12.6 +/- 3.9 vs. 196.5 +/- 21.0 microl/min P < 0.01), which did not alter GFR in WT mice (164.0 +/- 16.7 vs. 173.3 +/- 6.7 microl/min, P = not significant). An elevation in renal cAMP, however, suggested an activation of the PGI(2)-cAMP-renin system in these Tg mice. Moreover, angiotensin-converting enzyme inhibition afforded protection against endotoxin-related AKI in these Tg mice. Thus endothelial PGIs-mediated PGI(2), as previously shown with endothelial nitric oxide synthase-mediated nitric oxide, contributes to renal protection against endotoxemia-related AKI. This effect may be overridden by excessive activation of the renin-angiotensin system in renal-specific PGIs Tg mice.
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PMID:Prostacyclin in endotoxemia-induced acute kidney injury: cyclooxygenase inhibition and renal prostacyclin synthase transgenic mice. 1765 70

Both inflammation and thrombosis can be orchestrated by the interactions between circulating cells, such as leukocytes and platelets, with vascular, endothelial and smooth muscle cells, which, during activation or apoptosis, can release circulating microparticles (MPs). Indeed, MPs are membrane vesicles with procoagulant and proinflammatory properties. MPs are present in blood from healthy individuals and in patients under several pathological states, for instance sepsis, preeclampsia, Crohn's disease and diabetes, strengthening the notion that MPs may play a role in these diseases. Circulating MPs or those generated in vitro from apoptotic T cells display deleterious effects on endothelial and/or vasomotor function. In contrast, MPs might be protective to endothelial cells. We have shown that MPs harboring the morphogen sonic hedgehog may represent a new therapeutic approach against endothelial dysfunction during acute severe endothelial injury. Indeed, these types of MPs induce NO release, decrease production of reactive oxygen species and induce angiogenesis from endothelial cells. This protective role for the endothelium was confirmed also by their in vivo injection in mice in which they were also able to reverse endothelial dysfunction in a model of heart ischemia/reperfusion. On the contrary, MPs from preeclamptic women compared to those from normal pregnant women showed pro-inflammatory properties in the vascular wall inducing vascular hyporeactivity in vessels from humans and mice. These effects were associated with complex interactions between NO and cyclooxygenase systems via endothelial cell activation. Altogether, these findings suggest that MPs can be considered as vectors of biological messages for vascular homeostasis, during immunity and inflammation.
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PMID:Microparticles are vectors of paradoxical information in vascular cells including the endothelium: role in health and diseases. 1827 88

Renal excretion of organic anions such as para-aminohippurate is reduced during severe sepsis and following ischemia/reperfusion injury. In order to better define the pathophysiology of sepsis-associated renal tubular dysfunction we measured the effect of lipopolysaccharide on renocortical organic anion transporter (OAT) expression in the rat. Prostaglandin E2 (PGE2) downregulates OATs in vitro, therefore, we also evaluated the effect of the cyclooxygenase (COX)-2 inhibitor parecoxib on this process. Endotoxemia caused a time- and dose-dependent decrease of OAT1 and OAT3 expression that paralleled increased renocortical COX-2 expression and PGE2 formation. Pretreatment with parecoxib decreased endotoxin-stimulated PGE(2) formation. Parecoxib attenuated OAT1 and OAT3 gene repression in the rat kidney following endotoxin treatment and during ischemia/reperfusion-induced acute renal injury. COX-2 inhibition improved the creatinine clearance in lipopolysaccharide-treated rats but not after ischemia/reperfusion-induced acute renal injury. The decreased clearance of para-aminohippurate in rats following endotoxin- or ischemia/reperfusion-induced renal injury was improved by parecoxib. Our findings show that COX-2 derived prostanoids downregulate OATs during lipopolysaccharide-induced acute renal injury.
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PMID:COX-2 inhibition attenuates endotoxin-induced downregulation of organic anion transporters in the rat renal cortex. 1894 99


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