Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.69 (APC)
 16,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protein S (PS), a co-factor of activated protein C, is a vitamin K-dependent anticoagulant protein and is known to be produced extrahepatically. In the present study, the concentration of PS mRNA was determined tissue by tissue in the mouse, and it was high in lung, adrenal and heart as well as in liver. We further investigated the effects of lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 (IL-1) on the PS mRNA expression in murine tissues in vivo. Although LPS and TNF-alpha significantly decreased the expression level of PS mRNA in all tissues examined (e. g., lung, liver, heart, and kidney) and the PS antigen level in plasma, the suppressive effect of IL-1 on PS gene expression was limited to heart. More specifically, considerable amounts of PS mRNA and antigen were expressed in a cultured mouse cardiomyocyte cell line, and again, treatment with IL-1 decreased the PS expression in these cells. These observations raise a possibility that the expression of cardiac PS may contribute to the regional anticoagulant potential in heart, and suggest that the decreased PS expression by cytokines may result in an increase in the systemic and/or regional prothrombotic potential under inflammatory conditions.
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PMID:Expression of protein S in the murine heart and cultured mouse cardiomyocytes is down-regulated by cytokines. 1152 13

Thrombomodulin (TM) plays an important role in anticoagulation by forming a complex with thrombin, which subsequently activates protein C. TM is inactivated and downregulated by inflammatory cell mediators. This study examined whether bronchopneumonia is associated with changes in TM immunoreactivity, and whether a decrease in TM is accompanied by evidence of hypercoagulability, i.e. local deposition of fibrin. Double antibody staining for TM and fibrin was performed on lung tissue sections from patients who had died of pneumonia and from patients who had died rapidly, secondary to trauma. Inflammatory changes were assessed histologically and immunohistochemically using antibodies against interleukin-1alpha, tumor necrosis factor-alpha, and myeloperoxidase. Areas with bronchopneumonia exhibited markedly decreased endothelial TM staining of alveolar walls and small vessels. These changes were associated with prominent fibrin immunoreactivity. Some areas exhibited mild to moderate inflammation with little fibrin deposition and variable amounts of TM in adjacent vessels. This study is the first to relate changes of TM immunoreactivity levels to fibrin deposition in a human disease process. These data may have implications for pulmonary pathophysiology in patients with bronchopneumonia.
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PMID:Association between decreased pulmonary endothelial cell thrombomodulin and local fibrin deposition in pneumonia. 1173 75

The roles of inflammation and coagulation in the pathophysiology of sepsis are described. Sepsis results when an infectious insult triggers a localized inflammatory reaction that then spills over to cause systemic symptoms of fever or hypothermia, tachycardia, tachypnea, and either leukocytosis or leukopenia. These clinical symptoms are called the systemic inflammatory response syndrome. Severe sepsis is defined by dysfunction of one of the major organ systems or unexplained metabolic acidosis. The inflammatory reaction is mediated by the release of cytokines, including tumor necrosis factor-alpha, interleukins, and prostaglandins, from neutrophils and macrophages. The cytokines activate the extrinsic coagulation cascade and inhibit fibrinolysis. These overlapping processes result in microvascular thrombosis; thrombosis is one potential factor producing organ dysfunction. Activation of the coagulation system leads to consumption of endogenous anticoagulants (e.g., protein C and antithrombin); this may be an important factor in the development of microvascular coagulation. Antiinflammatory mediators as well as inflammatory mediators have a role in sepsis, and an excess of either can result in poor patient outcomes. Sepsis is a complex syndrome involving activation of a variety of systems.
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PMID:Pathophysiology of sepsis. 1188 12

Proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) are critically involved in activation of the coagulation system in sepsis, leading to disseminated intravascular coagulation (DIC). Natural anticoagulants such as antithrombin (AT) and activated protein C (APC) regulate the coagulation system by inhibiting thrombin generation. In addition to these anticoagulant effects, both AT and APC have been shown to attenuate inflammatory responses induced by various noxious stimuli in rats such as lipopolysaccharide (LPS) challenge. AT promotes the endothelial release of prostacyclin, a potent anti-inflammatory prostaglandin that inhibits the monocytic production of TNF-alpha, by interacting with cell-surface heparin-like substances. APC directly inhibits the production of TNF-alpha by inhibiting the activation of both nudear factor kappaB (NFkappaB) and activator protein-1 in monocytes stimulated with LPS. Thrombomodulin, an endothelial membranous integral protein that binds thrombin, exerts anti-inflammatory effects by generating APC. Furthermore, tissue factor pathway inhibitor, a natural anticoagulant for the extrinsic pathway of the coagulation system, also attenuates LPS-induced inflammatory responses in rats by inhibiting TNF-alpha production by monocytes. These findings strongly suggest that natural anticoagulants could regulate inflammatory responses as well as the coagulation system in rats by inhibiting the monocytic production of TNF-alpha. Such anti-inflammatory properties of natural anticoagulants are potentially important for their replacement in patients with sepsis who frequently develop DIC and organ failure as inflammatory responses.
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PMID:Regulation of inflammatory responses by natural anticoagulants. 1191 84

A condition of oxidative stress, due to perturbation of oxidant/antioxidant balance, has been suggested to play a role not only in the pathogenesis of human immunodeficiency virus (HIV) infection, but also in the promotion of a thrombophilic condition. Because various hemostatic dysfunctions usually considered as risk factors for thrombotic events were reported in HIV infection, this study was undertaken to investigate whether the oxidative phenomenon could promote a prothrombotic state in such condition. Erythrocyte glutathione peroxidase (GSH-Px), the major free-radical scavenger enzyme, and serum tumor necrosis factor-alpha (TNF-alpha) were evaluated in 33 consecutive HIV-infected out-patients and 35 matched HIV-negative healthy controls at a distance of any acute episode. Thrombin generation was explored by measuring the plasma levels of prothrombin fragment 1 + 2 (F1 + 2), whereas fibrin degradation products (D-dimer) and plasminogen activator inhibitor (PAI-1) activity were evaluated as indices of plasmin activity and fibrinolytic derangement. The anticoagulant pathway was investigated by measuring the plasma levels of antithrombin and protein C. Erythrocyte GSH-Px activity and serum TNF-alpha were significantly higher in HIV-infected patients when compared to controls. F1 + 2, D-dimer, and PAI-1 activity were increased in HIV-infected patients by comparison with controls. Normal antithrombin, but decreased protein C, was instead detected in HIV-infected patients. In the latter patients, serum TNF-alpha negatively correlated with both erythrocyte GSH-Px activity and plasma D-dimer. On the other hand, a positive correlation was shown between F1 + 2 and D-dimer and between D-dimer and GSH-Px activity. Furthermore, a trend toward increasing levels of GSH-Px with increasing PAI-1 activity was reported. These findings suggest a relationship between erythrocyte oxidative stress and the hypercoagulable condition during HIV infection.
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PMID:Increased erythrocyte glutathione peroxidase activity and serum tumor necrosis factor-alpha in HIV-infected patients: relationship to on-going prothrombotic state. 1198 8

The protein C (PC) pathway plays important roles in the regulation of the coagulation system and inflammatory response. This study evaluated the degree of PC activation in the airway of patients with bronchial asthma (BA), and the expression and regulation of PC and its receptor in airway epithelial cell lines. Thirteen BA patients and 8 healthy volunteers were enrolled in the study. BEAS-2B and A549 epithelial cell lines were used in experimental assays. Expression of anticoagulant factors was evaluated by RT-PCR and Western blotting. The activated protein C (APC)/thrombin (1.65 +/- 0.35 vs 3.34 +/- 0.59) and APC/PC (8.30 +/- 2.26 vs 24.41 +/- 9.88) ratios were significantly decreased and the concentrations of soluble thrombomodulin (TM) were significantly increased in induced sputum from BA patients compared with healthy subjects. Airway epithelial cells express PC, its receptor, and TM. PC antigen prepared from epithelial cells was significantly activated in the presence of thrombin. Thrombin increased the expression of PC antigen from lung epithelial cells. However, tumor necrosis factor-alpha, eotaxin, and RANTES (regulated on activation, normal T-cell expressed and secreted) decreased the expression of PC and its receptor in bronchial epithelial cells. Overall, these results showed for the first time that reduced activation of PC pathway occurs in the airway of BA patients and that TM, PC, and its receptor, are expressed by human airway epithelial cells. The expression of these PC pathway components was found to be downregulated by inflammatory cytokines. The decrease in PC activation may contribute to exacerbation of the inflammatory response in the airway of asthmatic patients.
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PMID:Activation of protein C pathway in the airways. 1210 56

An increased number of circulating endothelial cells (CECs) was demonstrated in alpha- and beta-thalassemic patients, beta-thalassemia/hemoglobin E (BE), both splenectomized (BE[S]) and non-splenectomized (BE[NS]), had higher numbers of CECs than alpha-thalassemia, both HbH (alpha-thal l/alpha-thal 2; H) and HbH with hemoglobin Constant Spring (alpha-thal 1/CS; H/CS). CECs were also increased in heterozygous HbE (EA) and homozygous HbE (EE). The highest level of tumor necrosis factor-alpha (TNF-alpha) was found in HbH/CS patients, whereas the highest levels of vascular endothelial growth factor (VEGF) was observed in BE[S] patients. Significant decreases, in protein C and protein S levels were found in both alpha- and beta-thalassemia compared with normal. Good correlations between the numbers of CEC and TNF-alpha, VEGF, protein C, and protein S levels were demonstrated in this study. In addition, markers for endothelial cell activation and injury (intercellular adhesion molecule-1, ICAM-1/CD54; vascular cell adhesion molecule-1, VCAM-1/CD106; and E-selectin, ELAM-1/CD62E) were detected on the surface of isolated CECs using immunofluorescence technique. Appearance of CECs with markers for endothelial cell activation, together with increased levels of TNF-alpha and VEGF and decreased levels of protein C and protein S in the circulation, may account for the propensity of vascular perturbation in thalassemic subjects.
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PMID:Increased circulating activated endothelial cells, vascular endothelial growth factor, and tumor necrosis factor in thalassemia. 1211 82

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

In the pathogenesis of sepsis and disseminated intravascular coagulation (DIC), dysfunctional anticoagulant pathways are important. The function of the protein C system in DIC is impaired because of low levels of protein C and down-regulation of thrombomodulin. The administration of (activated) protein C results in an improved outcome in experimental and clinical studies of DIC. It is unknown whether congenital deficiencies in the protein C system are associated with more severe DIC. The aim of the present study was to investigate the effect of a heterozygous deficiency of protein C on experimental DIC in mice. Mice with single-allele targeted disruption of the protein C gene (PC+/-) mice and wild-type littermates (PC+/+) were injected with Escherichia coli endotoxin (50 mg/kg) intraperitoneally. PC+/-mice had more severe DIC, as evidenced by a greater decrease in fibrinogen level and a larger drop in platelet count. Histologic examination showed more fibrin deposition in lungs, kidneys, and liver in mice with a heterozygous deficiency of protein C. Interestingly, PC+/- mice had significantly higher levels of proinflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and IL-1beta, indicating an interaction between the protein C system and the inflammatory response. Survival was lower at 12 and 24 hours after endotoxin in the PC+/- mice. These results confirm the important role of the protein C system in the coagulative-inflammatory response on endotoxemia and may suggest that congenital deficiencies in the protein C system are associated with more severe DIC and adverse outcome in sepsis.
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PMID:Aggravation of endotoxin-induced disseminated intravascular coagulation and cytokine activation in heterozygous protein-C-deficient mice. 1260 41


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