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)

The thrombomodulin (TM) gene was ablated in mice in a cell type-restricted manner from vascular endothelium by Cre-recombinase-mediated excision controlled by the endothelial cell lineage-specific Tie2 promoter. Forty percent of mutant (TMLox-) mice display a distinct lethal embryonic phenotype not observed in completely TM-deficient embryos. The remaining 60% of TMLox mice survive beyond birth, but invariably succumb to a severe hypercoagulable state and massive thrombosis after 3 weeks, terminating in a lethal consumptive coagulopathy. The progression of thrombosis was age- and sex-dependent. Disruption of the TM/protein C pathway was not associated with a latent proinflammatory state. Disease onset and progression could be prevented by warfarin anticoagulation. These results show that in mice, loss of endothelial cell TM function causes spontaneous and fatal thrombosis in the arterial and venous circulation, resulting from unfettered activation of the coagulation system. The combination of complete disease penetrance, uniform disease onset at young age, large vessel thrombosis of the extremities and multiple organ systems, and consumptive coagulopathy as the disease end-point provides a unique mouse model of human thrombotic disease.
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PMID:Endothelium-specific loss of murine thrombomodulin disrupts the protein C anticoagulant pathway and causes juvenile-onset thrombosis. 1151 27

Behcet's disease (BD) is a multisystemic inflammatory disorder of unknown etiology that is sometimes associated with thrombosis in addition to systemic manifestations. However, the mechanism of hypercoagulability is not known. We evaluated the coagulation and fibrinolytic activities and the plasma total homocysteine levels of Korean BD patients in two cross-sectional studies. In the first study regarding coagulation and fibrinolytic activities, the levels of fibrinogen and von Willebrand factor (vWF) antigen were significantly higher in the BD patients than in the healthy controls (387.7+/-24.3 versus 240.6+/-8.8 mg/dl, p<0.001, and 131.9+/-8.8 versus 105.2+/-0.3%, p<0.01, respectively). The level of antithrombin III (AT III) was significantly lower in the BD patients (92.8+/-3.2 versus 106.3+/-2.6%, p<0.005). No differences were observed in the levels of plasminogen, protein C, or protein S activities. Activated protein C (APC) resistance was not observed in any BD patients. In the second study, the plasma total homocysteine levels of patients with a history of thrombosis (11.9+/-3.0 micromol/l) or disease activity (12.5+/-3.8 micromol/l) were found to be significantly higher than those of the controls (9.2+/-2.6 micromol/l, p<0.05, both). The plasma homocysteine concentrations in the thrombosis patients were positively correlated with plasma vWF levels; a relationship which suggests injury of the vascular endothelium (Spearman coefficient=0.857, p<0.01). Therefore, coagulation abnormality did not contribute to thrombotic complications, and higher levels of homocysteine may play a role in the hypercoagulablity of BD patients.
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PMID:Coagulation parameters and plasma total homocysteine levels in Behcet's disease. 1216 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

Despite several studies examining the contribution of allorecognition pathways to acute and chronic rejection of vascularized murine allografts, little data describing activation of alloreactive T cells by mouse vascular endothelium exist. We have used primary cultures of resting or IFN-gamma-activated C57BL/6 (H-2(b)) vascular endothelial cells as stimulators and CD8(+) T lymphocytes isolated from CBA/J (H-2(k)) mice as responders. Resting endothelium expressed low levels of MHC class I, which was markedly up-regulated after activation with IFN-gamma. It also expressed moderate levels of CD80 at a resting state and after activation. Both resting and activated endothelium were able to induce proliferation of unprimed CD8(+) T lymphocytes, with proliferation noted at earlier time points after coculture with activated endothelium. Activated endothelium was also able to induce proliferation of CD44(low) naive CD8(+) T lymphocytes. Activated CD8(+) T lymphocytes had the ability to produce IFN-gamma and IL-2, acquired an effector phenotype, and showed up-regulation of the antiapoptotic protein Bcl-x(L). Treatment with CTLA4-Ig led to marked reduction of T cell proliferation and a decrease in expression of Bcl-x(L). Moreover, we demonstrate that nonhemopoietic cells such as vascular endothelium induce proliferation of CD8(+) T lymphocytes in a B7-dependent fashion in vivo. These results suggest that vascular endothelium can act as an APC for CD8(+) direct allorecognition and may, therefore, play an important role in regulating immune processes of allograft rejection.
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PMID:Mouse vascular endothelium activates CD8+ T lymphocytes in a B7-dependent fashion. 1244 19

A study was carried out on activity of protein C4 in 73 surgical patients (coagulation test, reagents of company PEHAM). The reduction in activity of protein C was observed in patients with focal liver lesion related to disturbance of protein formation function. This percent of disturbances in protein C system is more often found in patients with vascular pathology. This is explained by the mechanism of its action and implication of vascular endothelium into the process. Disturbances in patients with injury infection are stipulated with activity of C and S proteins and availability of mutant factor V--factor Leiden in patients with diabetes. In the first days after surgical intervention the activity of C protein was much reduced. The obtained results emphasize the importance of research in the system of protein C in surgical patients.
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PMID:[Disorders of protein C anticoagulant system in various clinical conditions]. 1251 42

Cerebrovascular accidents are one of the life-threatening complications of diabetic ketoacidosis (DKA) in children and adolescents. Our objective was to evaluate the effect of DKA and its treatment on factors known to affect thrombotic activity (protein C; protein S; von Willebrand factor, fibrinogen; homocysteine; and folate) by comparing seven adolescents with DKA prior to treatment and at 6, 24, and 120 hours after initiation of treatment. We found that protein C activity was significantly decreased by DKA, but normalized slowly following treatment. Free protein S was low throughout the study. Protein C antigen and protein S antigen showed varying degrees ofchange within the first 24 hours, but remained in the normal range, with the exception of the initial value of protein C antigen, which was elevated. von Willebrand factor (vWF) antigen and vWF activity were both significantly increased prior to treatment, but decreased with treatment. However, vWF activity remained elevated at 120 hours. Fibrinogen concentrations showed no significant changes throughout the study. Homocysteine was significantly decreased prior to treatment and increased with the initiation of treatment Folate was significantly increased prior to treatment, and decreased to high normal levels. The increased vWF and the decreased levels of protein C activity and of free protein S support the hypothesis that DKA and its treatment results in a prothrombotic state and activation of the vascular endothelium, which, in turn, predispose to cerebrovascular accidents.
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PMID:Diabetic ketoacidosis promotes a prothrombotic state. 1266 20

Inflammation represents the interaction of the immune and coagulation systems in an attempt to restore normal hemostasis following injury. The underlying basis of the interrelationship between these two physiological systems revolves around the following: a) the activation of coagulation by inflammation, b) the augmentation of the inflammatory response by coagulation, c) the significant attenuation of inflammation by the anticoagulant response and d) the separate influence of the vascular endothelium on coagulation and inflammation as well as its mediation or control of the cross-talk between these two physiological systems. In hemostasis, the protein C anticoagulant pathway is a major mechanism that functions to prevent the development of a pathological thrombus through the regulation of the procoagulant pathway. The endothelium is essential in maintaining a physiological balance between the anticoagulant and procoagulant pathways with proinflammatory cytokines functioning, in part, to regulate endothelial-cell- surface associated coagulation and anticoagulation proteins. In addition to its anticoagulant properties, activated protein C can also function as a regulator of proinflammatory cytokine production. Current evidence suggests that activated protein C may act to control inflammation through NF-kappaB and/or nitric oxide synthase. A better understanding of the relationship between APC and inflammation may provide new targets for drug design.
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PMID:The relationship between inflammation and the anticoagulant pathway: the emerging role of endothelial nitric oxide synthase (eNOS). 1503 95

Diabetic retinopathy (DR) is a major cause of blindness in the working population of the Western world and there is no doubt that its prevalence is strongly related to the duration of diabetes and the glycemic control. However, although intensive diabetes management, with the goal of achieving near-normal glycemia, has been shown to prevent and/or delay the onset of DR, there is now ample of evidence that the development of this microangiopathy is a multifactorial process in which genetic, metabolic, haemostatic and growth factors play an important role. Moreover, given the suggestions that immunological mechanisms might have a role in the pathogenesis of diabetic microangiopathy via immune complex deposition, it has been hypothesized that antiphospholipid antibodies (A-Ab) directed against endothelial antigens could be responsible for initiating vascular injury. In particular, not only A-Ab production was found to be increased in patients with overt nephropathy or macroangiopathy but also Lupus Anticoagulant positivity, representing an intersection point between immune and haemostatic alterations, has been highlighted as a potential and additional risk factor in the pathogenesis of microangiopathy in type 1 diabetics. Moreover, given the high levels of activated protein C, endothelin-1 and thrombo-modulin that have been observed in normo-albuminuric and uncomplicated patients, it has been concluded that the vascular endothelium shifts pathologically from an antithrombotic to a prothrombotic state even in the early phases of the disease. This condition was found to be more pronounced in subjects with anticardiolipin positivity and/or high circulating immune complexes concentrations, since they possess the ability not only to induce platelet activation and aggregation but also to activate the complement system via the classical pathway. Therefore, a potential synergism between generation of autoantibodies, haemostatic alterations and endothelial stress has been suggested, a stimulating hypothesis that needs further studies to be clarified in its complexity.
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PMID:Are phospholipid-binding antibodies implicated in the pathogenesis of diabetic microangiopathy? 1523 81

Activated protein C (APC) has anti-inflammatory and vascular protective effects independent of anticoagulation. We previously identified the prototypical thrombin receptor, protease-activated receptor-1 (PAR1), as part of a novel APC-endothelial cell protein C receptor (EPCR) signaling pathway in endothelial cells. Experiments in wild-type and PAR1(-/-) mice demonstrated that intravenous injection of APC leads to PAR1-dependent gene induction in the lung. The vascular endothelium undergoes profound changes in severe sepsis, the approved therapeutic indication for APC. Similar to PAR1, APC activated PAR2 through canonical cleavage. Although PAR2 was up-regulated in cytokine-stimulated endothelial cells, APC signaling remained PAR1-dependent. Large scale gene expression profiling documented marked differences in both up- and down-regulated genes between APC and thrombin signaling in cytokine-stimulated cells. APC down-regulated transcripts for proapoptotic proteins including p53 and thrombospondin-1, but p53 was unchanged, and thrombospondin was even up-regulated by thrombin. Concordant PAR1-dependent effects on protein levels were found. Thus, by signaling through the same receptor PAR1, APC, and thrombin can exert distinct biological effects in perturbed endothelium. These data may explain how APC can be therapeutically protective through the EPCR-PAR1 signaling despite ongoing thrombin generation due to disseminated intravascular coagulopathy.
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PMID:Protease-activated receptor-1 signaling by activated protein C in cytokine-perturbed endothelial cells is distinct from thrombin signaling. 1576 47

Dendritic cells (DC) migrate from sites of inflammation to lymph nodes to initiate primary immune responses, but the molecular mechanisms by which DC are replenished in the lungs during ongoing pulmonary inflammation are unknown. To address this question, we analyzed the secondary pulmonary immune response of Ag-primed mice to intratracheal challenge with the particulate T cell-dependent Ag sheep erythrocytes (SRBC). We studied wild-type C57BL/6 mice and syngeneic gene-targeted mice lacking either both endothelial selectins (CD62E and CD62P), or the chemokine receptors CCR2 or CCR6. DC, defined as non-autofluorescent, MHC class II(+)CD11c(mod) cells, were detected in blood, enzyme-digested minced lung, and bronchoalveolar lavage fluid using flow cytometry and immunohistology. Compared with control mice, Ag challenge increased the frequency and absolute numbers of DC, peaking at day 1 in peripheral blood (6.5-fold increase in frequency), day 3 in lung mince (20-fold increase in total DC), and day 4 in bronchoalveolar lavage fluid (55-fold increase in total DC). Most lung DC expressed CD11c, CD11b, and low levels of MHC class II, CD40, CD80, and CD86, consistent with an immature myeloid phenotype. DC accumulation depended in part upon CCR2 and CCR6, but not endothelial selectins. Thus, during lung inflammation, immature myeloid DC from the bloodstream replace emigrating immature DC and transiently increase total intrapulmonary APC numbers. Early DC recruitment depends in part on CCR2 to traverse vascular endothelium, plus CCR6 to traverse alveolar epithelium. The recruitment of circulating immature DC represents a potential therapeutic step at which to modulate immunological lung diseases.
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PMID:CCR2 and CCR6, but not endothelial selectins, mediate the accumulation of immature dendritic cells within the lungs of mice in response to particulate antigen. 1600 85


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