Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The protein C (PC) pathway has recently been suggested to play a role in the regulation of the inflammatory response. To further extend the anti-inflammatory effect of activated PC (APC) in vivo, particularly its biological relevance to human disease, the activity of APC in the mucosa of patients with Helicobacter pylori-associated gastritis and the effect of vacuolating cytotoxin (VacA), cytotoxin-associated antigen (CagA), and H. pylori lipopolysaccharide (LPS) on PC activation were evaluated. This study comprised 35 patients with chronic gastritis. There were 20 patients with and 15 without H. pylori infection. The levels of PC and APC-PC inhibitor (PCI) complex were measured by immunoassays. The level of PC was significantly decreased and the level of APC-PCI complex was significantly increased in biopsy specimens from gastric corpus and antrum in patients with H. pylori-associated gastritis as compared to H. pylori-negative subjects. The concentrations of VacA, CagA, and LPS were significantly correlated with those of the APC-PCI complex in biopsy mucosal specimens from the gastric corpus and antrum. H. pylori LPS, VacA, and CagA induced a dose-dependent activation of PC on the surface of monocytic cells. APC inhibited the secretion of tumor necrosis factor alpha (TNF-alpha) induced by H. pylori LPS. Overall, these results suggest that H. pylori infection is associated with increased APC generation in the gastric mucosa. The inhibitory activity of APC on TNF-alpha secretion may serve to protect H. pylori-induced gastric mucosal damage.
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PMID:Role of activated protein C in Helicobacter pylori-associated gastritis. 1076 83

Activated protein C (APC) is a natural anticoagulant and inhibits thrombin generation by degrading factors Va and VIIIa. We evaluated the ability of APC to inhibit blood coagulation triggered by lipopolysaccharide (LPS)-stimulated [tissue factor (TF)-expressing] human mononuclear cells (MNCs) or umbilical vein endothelial cells (HUVECs). Using a plasma recalcification assay, we found that APC (up to 53.3 nmol/l final concentration) had a poor anticoagulant effect in the presence of LPS-stimulated MNCs, whereas it caused a marked prolongation of clotting time in the presence of LPS-stimulated HUVECs. A poor response to APC was also observed when platelet-free MNCs, monocyte-enriched preparations or the monocytoid cell line U937 were tested. Using a TF-independent (FXa-induced) thrombin generation assay, we demonstrated that both LPS-stimulated and unstimulated MNCs negated the inhibitory activity of APC. Direct determination of FVa activity indicated that MNCs were less efficient than HUVECs in promoting FVa inactivation by APC. Together, our results suggest that MNCs, at variance with HUVECs, protect factor Va from inactivation by APC, probably through the expression of a membrane component not present on endothelial cells. These strengthen the importance of monocytes in fibrin deposition associated with pathological conditions characterized by monocyte recruitment and activation.
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PMID:Monocytes, but not endothelial cells, downregulate the anticoagulant activity of activated protein C. 1116 57

This study investigated the respiratory burst responses of rat resident peritoneal macrophages and of peritoneal macrophages stimulated 5 days previously with viable spores of the fish infecting microsporidian Microgemma caulleryi. Nitric oxide production by resident macrophages and prestimulated macrophages in response to viable microsporidian spores was significantly lower than in response to Escherichia coli lipopolysaccharide (LPS) (nitrite concentration in medium 57 +/- 1 microM for resident macrophages stimulated with LPS versus 31 +/- 1 microM for resident macrophages stimulated with microsporidian spores and 36 +/- 4 microM for M. caulleryi prestimulated macrophages; P < 0.05). Extracellular release of reactive oxygen species (ROS) by resident macrophages in response to microsporidian spores was similar to that in response to Kluyveromyces lactis yeast cells and to that in response to phorbol myristate (a stimulator of protein C kinase). Intracellular ROS production by resident macrophages in response to microsporidian spores was similar to that produced in response to yeast cells. Both extracellular ROS production and intracellular ROS production (in response to all stimuli) were significantly lower after in vivo prestimulation of macrophages with microsporidian spores. These results demonstrate that microsporidian spores of species other than those that habitually infect mammals are capable of modulating the respiratory burst of rat peritoneal macrophages. Such modulation may contribute to avoidance by the microsporidian of cytotoxic responses associated with the respiratory burst.
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PMID:Respiratory burst responses of rat macrophages to microsporidian spores. 1142 46

Many sequelae associated with endotoxaemic-induced shock result from excessive production of the cytokine mediators, tumour necrosis factor alpha (TNF-alpha), interleukin 1 (IL-1) and IL-6 from lipopolysaccharide (LPS)-activated monocytes. Protein C (PC)/activated protein C (APC) has potent cytokine-modifying properties and is protective in animal models and human clinical trials of sepsis. The precise mechanism by which this anti-inflammatory response is achieved remains unknown; however, the recently described endothelial protein C receptor (EPCR) appears to be essential for this function. The pivotal role that monocytes play in the pathophysiology of septic shock led us to investigate the possible expression of a protein C receptor on the monocyte membrane. We used similarity algorithms to screen human sequence databases for paralogues of the EPCR but found none. However, using reverse transcription-polymerase chain reaction (RT-PCR), we detected an mRNA transcribed in primary human monocytes and THP1 cells that was identical to human EPCR mRNA. We also used immunocytochemical analysis to demonstrate the expression of a protein C receptor on the surface of monocytes encoded by the same gene as EPCR. These results confirm a new member of the protein C pathway involving primary monocytes. Further characterization will be necessary to compare and contrast its biological properties with those of EPCR.
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PMID:Characterization of protein C receptor expression in monocytes. 1170 43

Lipopolysaccharides in the outer membrane of Neisseria meningitidis are key molecules that induce inflammation and cause meningitis and shock. Mutant strains, with altered lipid A, the toxic moiety of lipopolysaccharide, or completely lacking lipopolysaccharide, induce significantly less inflammation than wild-type strains. Polymorphism of the Fc gamma receptors and interleukin-10 gene but not of the Toll-like receptor 4 may influence the development of meningococcal infection. Mannan-binding lectin is involved in complement activation, the regulation of adhesion molecules and cytokine production induced by meningococci. The activation of protein C by the thrombomodulin protein C receptor complex on the endothelial cell surface appears to be reduced in meningococcal sepsis but is still sufficient to convert protein C to activated protein C in patients treated with concentrated protein C.
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PMID:Current concepts in the role of the host response in Neisseria meningitidis septic shock. 1201 58

Activated protein C (APC), an important natural anticoagulant, inhibits tumor necrosis factor-alpha (TNF-alpha) production and attenuates various deleterious events induced by lipopolysaccharide (LPS), contributing thereby to a significant reduction of mortality in patients with severe sepsis. In this study, we investigated the mechanism(s) by which APC inhibits TNF-alpha production by LPS-stimulated human monocytes in vitro. Although APC inhibited LPS-induced TNF-alpha production in a concentration-dependent fashion, diisopropyl fluorophosphate-treated APC, an active-site-blocked APC, had no effect. APC inhibited both the binding of nuclear factor-kappa B (NF-kappa B) to target sites and the degradation of I kappa B alpha. APC also inhibited both the binding of activator protein-1 (AP-1) to target sites and the activation of mitogen-activated protein kinase pathways. These observations strongly suggest that APC inhibited LPS-induced TNF-alpha production by inhibiting the activation of both NF-kappa B and AP-1 and that the inhibitory activity of APC might depend on its serine protease activity. These results would at least partly explain the mechanism(s) by which APC reduces the tissue injury seen in animal models of sepsis and in patients with sepsis.
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PMID:Activated protein C inhibits lipopolysaccharide-induced tumor necrosis factor-alpha production by inhibiting activation of both nuclear factor-kappa B and activator protein-1 in human monocytes. 2213 Oct 84

Vascular endothelial cells (EC) play a key role in a variety of pathophysiologic processes, such as angiogenesis, inflammation, cancer metastasis, and vascular diseases. As part of a strategy to identify all genes expressed in human EC, a full-length cDNA encoding a potential secreted protein harboring 10 epidermal growth factor (EGF)-like domains and one CUB domain at the carboxyl terminus (termed, SCUBE1 for Signal peptide-CUB-EGF-like domain containing protein 1) was identified. SCUBE1 shares homology with several protein families, including members of the fibrillin and Notch families, and the anticoagulant proteins, thrombomodulin and protein C. SCUBE1 mRNA is found in several highly vascularized tissues such as liver, kidney, lung, spleen, and brain and is selectively expressed in EC by in situ hybridization. SCUBE1 is a secreted glycoprotein that can form oligomers and manifests a stable association with the cell surface. A second gene encoding a homologue (designated SCUBE2) was also identified and is expressed in EC as well as other cell types. SCUBE2 is also a cell-surface protein and can form a heteromeric complex with SCUBE1. Both SCUBE1 and SCUBE2 are rapidly down-regulated in EC after interleukin-1beta and tumor necrosis factor-alpha treatment in vitro and after lipopolysaccharide injection in vivo. Thus, SCUBE1 and SCUBE2 define an emerging family of human secreted proteins that are expressed in vascular endothelium and may play important roles in development, inflammation, and thrombosis.
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PMID:Identification of a novel family of cell-surface proteins expressed in human vascular endothelium. 1227 Sep 31

Sepsis caused by gram-negative bacteria and that caused by gram-positive bacteria often manifest similar clinical features. We investigated plasma proinflammatory cytokine profiles in patients with sepsis due to gram-positive and gram-negative bacteria and studied the cytokine production and differential gene regulation of leukocytes stimulated ex vivo with Escherichia coli lipopolysaccharide or heat-killed Staphylococcus aureus. Concentrations of tumor necrosis factor alpha, interleukin 1 receptor antagonist (IL-1Ra), IL-8, IL-10, IL-18 binding protein, procalcitonin, and protein C in plasma did not differ between patients with sepsis due to gram-negative and gram-positive bacteria. However, plasma IL-1beta, IL-6, and IL-18 concentrations were significantly higher in patients with sepsis due to gram-positive bacteria. Ex vivo stimulation of whole blood with heat-killed S. aureus markedly increased IL-1beta and IL-18 levels more than E. coli lipopolysaccharide stimulation. Microarray analysis revealed at least 359 cross-validated probe sets (genes) significant at the P < 0.001 level whose expression discriminated among gram-negative-organism-stimulated, gram-positive-organism-stimulated, and unstimulated whole-blood leukocytes. The host inflammatory responses to gram-negative and gram-positive stimuli share some common response elements but also exhibit distinct patterns of cytokine appearance and leukocyte gene expression.
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PMID:Molecular characterization of the acute inflammatory response to infections with gram-negative versus gram-positive bacteria. 1450 May 2

The thrombomodulin-protein C-protein S (TM-PC-PS) pathway exerts anticoagulant and anti-inflammatory effects. We investigated the role of TM in the pulmonary immune response in vivo by the use of mice with a mutation in the TM gene (TM(pro/pro)) that was earlier found to result in a minimal capacity for activated PC (APC) generation in the circulation. We here demonstrate that TM(pro/pro) mice also display a strongly reduced capacity to produce APC in the alveolar compartment upon intrapulmonary delivery of PC and thrombin. We monitored procoagulant and inflammatory changes in the lung during Gram-positive (Streptococcus pneumoniae) and Gram-negative (Klebsiella pneumoniae) pneumonia and after local administration of lipopolysaccharide (LPS). Bacterial pneumonia was associated with fibrin(ogen) depositions in the lung that colocalized with inflammatory infiltrates. LPS also induced a rise in thrombin-antithrombin complexes in bronchoalveolar lavage fluid. These pulmonary procoagulant responses were unaltered in TM(pro/pro) mice, except for enhanced fibrin(ogen) deposition during pneumococcal pneumonia. In addition, TM(pro/pro) mice displayed unchanged antibacterial defense, neutrophil recruitment, and cytokine/chemokine levels. These data suggest that the capacity of TM to generate APC does not play a role of importance in the pulmonary response to respiratory pathogens or LPS.
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PMID:Thrombomodulin mutant mice with a strongly reduced capacity to generate activated protein C have an unaltered pulmonary immune response to respiratory pathogens and lipopolysaccharide. 1459 28

Gram-negative sepsis is associated with disseminated intravascular coagulation (DIC) due to endothelial damage, which is induced by inflammatory mediators released from phagocytes activated by lipopolysaccharide (LPS). DIC is a systemic hemorrhagic syndrome, which results from the consumption of coagulation factors for the formation of multiple thrombi in the systemic microvessels; it is associated with multiple organ failure. Therefore, not only the systemic activation of coagulation but also the inflammatory response has been perceived as the therapeutic target for DIC in sepsis. We gave attention that protein C inhibitor (PCI) acts as an inhibitor of both plasma kallikrein and thrombin, which are known to act not only as procoagulant proteases but also as chemotactic factors toward phagocytes. Then, we hypothesized that PCI possibly acts as an anti-DIC agent rather than an inhibitor of the protein C anticoagulant pathway under the pathophysiology of DIC, accompanied by the decrease in the thrombomodulin expression on endothelial cells. Our studies have suggested that PCI purified from human urine (uPCI) improves the pathophysiology of DIC through the inhibition of activities of plasma kallikrein and thrombin, and the activities of PCI are regulated by N-glycans. This review introduces the anti-DIC action of PCI and about the modification of N-glycosylation site(s) of PCI to heighten the value of PCI as an anti-DIC agent.
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PMID:Protein C inhibitor as an anti-disseminated intravascular coagulation agent--mechanism and modification. 1532 Aug 3


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