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

2005 ◽  
Vol 93 (04) ◽  
pp. 743-750 ◽  
Author(s):  
Sarah Horn ◽  
Siegfried Lang ◽  
Kenji Fukudome ◽  
Adriane Nahrup ◽  
Ursula Hoffmann ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Protein C ◽  
Activated Protein C ◽  
Cell Protein ◽  
Mrna Levels ◽  
Endothelial Protein C Receptor ◽  
Drotrecogin Alfa Activated ◽  
Cox 2 ◽  
Vitro Effect

SummaryProstacyclin (PGI2) 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 PGI2 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 PGI2 release from human umbilical vein endothelial cells (HUVEC). We found that rhAPC, at supra-therapeutical concentrations (500ng/ml-20μg/ ml), upregulated the amount of COX-2-mRNA in HUVEC at t=3–9h and caused a time- and dose-dependent release of 6-keto PGF1α, the stable hydrolysis product of prostacyclin. RhAPC further increased the stimulating effect of tumor necrosis factor-α (TNF-α) and thrombin on COX-2-mRNA-levels. Transcript levels of cyclooxygenase-1 (COX-1) and prostagland-in I2 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 6keto PGF1α-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 up-regulation 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.

Abstract 34: Endogenous Superoxide Dismutase Protects From Impaired Generation of Activated Protein C and Enhanced Susceptibility to Experimental Thrombosis in Mice

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Sanjana Dayal ◽  
Sean X Gu ◽  
Katinan M Wilson ◽  
Ryan Hutchins ◽  
Steven R Lentz
Keyword(s):  
Superoxide Dismutase ◽  
Protein C ◽  
Activated Protein C ◽  
Vena Cava ◽  
Oxidative Modification ◽  
Mrna Levels ◽  
Endothelial Protein C Receptor ◽  
Experimental Thrombosis

In vitro studies have suggested that reactive oxygen species such as superoxide can produce prothrombotic effects, including enhanced platelet activation, increased tissue factor (TF) expression, and an oxidative modification in thrombomodulin impairing its capacity to enhance the generation of activated protein C (APC) by thrombin. It is not known, however, if elevated levels of superoxide accelerate susceptibility to experimental thrombosis in vivo . We used mice genetically deficient in superoxide dismutase-1 (SOD1, an antioxidant enzyme that dismutates superoxide to hydrogen peroxide), to test the hypothesis that lack of SOD1 enhances susceptibility to thrombosis. Susceptibility to carotid artery thrombosis in a photochemical injury model demonstrated that Sod1-/- mice formed stable occlusions significantly faster than Sod1+/+ mice (P<0.05). In an inferior vena cava (IVC) stasis model Sod1- /- mice developed significantly larger thrombi 48 hours after IVC ligation (P<0.05 vs. Sod1+/+ mice). After activation with thrombin (0.5 U/ml) or convulxin (200 ng/ml), no differences in surface expression of P-selectin or binding of fibrinogen were observed between platelets from Sod1-/- and Sod1+/+ mice. The expression of TF mRNA in lung measured by real time qPCR showed similar levels in Sod1-/- and Sod1 +/+ mice. However, the activation of exogenous protein C by thrombin in lung homogenates was decreased in Sod1 -/- mice (P<0.05 vs. Sod1 +/+ mice). Further, in vivo generation of activated protein C in response to thrombin (40 U/Kg) infusion was significantly lower in Sod1-/- mice (P<0.05 vs. Sod1+/+ mice). No differences in mRNA levels for thrombomodulin or endothelial protein C receptor were detected in Sod1 -/- mice vs. Sod1 +/+ mice, suggesting that altered generation of activated protein C in Sod1-/- mice may be related to a direct oxidative effect on thrombomodulin. In accordance, thrombomodulin treated with xanthine/hypoxanthine showed 40% loss of ability to activate protein C that was overcome by addition of SOD and catalase (P<0.05). We conclude that endogenous SOD1 in mice protects from impaired generation of activated protein C and accelerated thrombosis.

Activated protein C induces the release of microparticle-associated endothelial protein C receptor

Blood ◽  
2005 ◽  
Vol 105 (4) ◽  
pp. 1515-1522 ◽  
Author(s):  
Margarita Pérez-Casal ◽  
Colin Downey ◽  
Kenji Fukudome ◽  
Gernot Marx ◽  
Cheng Hock Toh
Keyword(s):  
Endothelial Cells ◽  
Protein C ◽  
Umbilical Vein ◽  
Activated Protein C ◽  
Enzyme Linked Immunosorbent Assay ◽  
Factor V ◽  
Endothelial Protein C Receptor ◽  
Microparticle Formation ◽  
Umbilical Vein Endothelial Cells

Abstract Activated protein C (APC) treatment is now used for patients with severe sepsis. We investigated its effect in vitro on primary, physiologically relevant cells and demonstrate a novel mechanism of endothelial protein C receptor (EPCR) release that is not inhibited by metalloproteinase inhibitors. Exposure of human umbilical vein endothelial cells or monocytes to APC (6.25-100 nM) results in the release of EPCR-containing microparticles, as demonstrated by confocal microscopy and characterized through flow cytometry, enzyme-linked immunosorbent assay quantitation of isolated microparticles, and Western blotting. The phenomenon is time- and concentration-dependent and requires the APC active site, EPCR, and protease activated receptor 1 (PAR1) on endothelial cells. Neither protein C nor boiled or d-Phe-Pro-Arg-chloromethylketone–blocked APC can induce microparticle formation and antibody blockade of EPCR or PAR1 cleavage and activation abrogates this APC action. Coincubation with hirudin does not alter the APC effect. The released microparticle bound is full-length EPCR (49 kDa) and APC retains factor V–inactivating activity. Although tumor necrosis factor-α (10 ng/mL) can also induce microparticle-associated EPCR release to a similar extent as APC (100 nM), it is only APC-induced microparticles that contain bound APC. This novel observation could provide new insights into the consequences of APC therapy in the septic patient.

Role of activated protein C and its receptor in inhibition of tumor metastasis

Blood ◽  
2009 ◽  
Vol 113 (14) ◽  
pp. 3371-3374 ◽  
Author(s):  
Michael Bezuhly ◽  
Robyn Cullen ◽  
Charles T. Esmon ◽  
Steven F. Morris ◽  
Kenneth A. West ◽  
...  
Keyword(s):  
Protein C ◽  
Lung Metastases ◽  
Activated Protein C ◽  
Mrna Levels ◽  
Endothelial Protein C Receptor ◽  
Tumor Cell Adhesion ◽  
Similar Reduction ◽  
Tumor Endothelium

Abstract Engagement of endothelial protein C receptor (EPCR) by activated protein C (aPC) decreases expression of endothelial adhesion molecules implicated in tumor-endothelium interactions. We examined the role of the aPC/EPCR pathway on tumor migration and metastasis. In vitro, B16-F10 melanoma cells showed decreased adhesion to and transmigration through endothelium treated with recombinant human aPC (rhaPC). In murine B16-F10 metastasis models, transgenic EPCR overexpressing (Tie2-EPCR) mice exhibited marked reductions in liver (50%) and lung (92%) metastases compared with wild-type (WT) animals. Intravital imaging showed reduced B16-F10 entrapment within livers of Tie2-EPCR compared with WT mice. A similar reduction was observed in WT mice treated with rhaPC. Strikingly, rhaPC treatment resulted in a 44% reduction in lung metastases. This was associated with decreased lung P-selectin and TNF-α mRNA levels. These findings support an important role for the aPC/EPCR pathway in reducing metastasis via inhibition of tumor cell adhesion and transmigration.

scholarly journals Inhibition of staurosporine-induced apoptosis of endothelial cells by activated protein C requires protease-activated receptor-1 and endothelial cell protein C receptor

2003 ◽  
Vol 373 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Laurent O. MOSNIER ◽  
John H. GRIFFIN
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Active Site ◽  
Protein C ◽  
Activated Protein C ◽  
Cell Protein ◽  
Protease Activated Receptor 1 ◽  
Induced Apoptosis ◽  
Apoptotic Effects ◽  
Dose Dependent

In a model of staurosporine-induced apoptosis using EAhy926 endothelial cells, inhibition of apoptosis by activated protein C was dose-dependent and required the enzyme's active site, implicating activated protein C-mediated proteolysis. Consistent with this implication, both protease-activated receptor-1 (PAR-1) and endothelial cell protein C receptor (EPCR) were required for the anti-apoptotic effects of activated protein C.

Activated protein C targets immune cells and rheumatoid synovial fibroblasts to prevent inflammatory arthritis in mice

Rheumatology ◽  
2019 ◽  
Vol 58 (10) ◽  
pp. 1850-1860 ◽  
Author(s):  
Meilang Xue ◽  
Suat Dervish ◽  
Kelly J McKelvey ◽  
Lyn March ◽  
Fang Wang ◽  
...  
Keyword(s):  
Protein C ◽  
Activated Protein C ◽  
Synovial Fibroblasts ◽  
Endothelial Protein C Receptor ◽  
Mouse Thymus ◽  
Tnf Α ◽  
Thymus Cells ◽  
Proliferation And Invasion

Abstract Objectives To investigate whether activated protein C (APC), a physiological anticoagulant can inhibit the inflammatory/invasive properties of immune cells and rheumatoid arthritis synovial fibroblasts (RASFs) in vitro and prevent inflammatory arthritis in murine antigen-induced arthritis (AIA) and CIA models. Methods RASFs isolated from synovial tissues of patients with RA, human peripheral blood mononuclear cells (PBMCs) and mouse thymus cells were treated with APC or TNF-α/IL-17 and the following assays were performed: RASF proliferation and invasion by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and cell invasion assays, respectively; cytokines and signalling molecules using ELISA or western blot; Th1 and Th17 phenotypes in human PBMCs or mouse thymus cells by flow cytometry. The in vivo effect of APC was evaluated in AIA and CIA models. Results In vitro, APC inhibited IL-1β, IL-17 and TNF-α production, IL-17-stimulated cell proliferation and invasion and p21 and nuclear factor κB activation in RASFs. In mouse thymus cells and human PBMCs, APC suppressed Th1 and Th17 phenotypes. In vivo, APC inhibited pannus formation, cartilage destruction and arthritis incidence/severity in both CIA and AIA models. In CIA, serum levels of IL-1β, IL-6, IL-17, TNF-α and soluble endothelial protein C receptor were significantly reduced by APC treatment. Blocking endothelial protein C receptor, the specific receptor for APC, abolished the early or preventative effect of APC in AIA. Conclusion APC prevents the onset and development of arthritis in CIA and AIA models via suppressing inflammation, Th1/Th17 phenotypes and RASF invasion, which is likely mediated via endothelial protein C receptor.

Contribution of polymorphisms in the endothelial protein C receptor gene to soluble endothelial protein C receptor and circulating activated protein C levels, and thrombotic risk

2004 ◽  
Vol 91 (05) ◽  
pp. 905-911 ◽  
Author(s):  
Pilar Medina ◽  
Silvia Navarro ◽  
Amparo Estellés ◽  
Amparo Vayá ◽  
Barry Woodhams ◽  
...  
Keyword(s):  
Venous Thromboembolism ◽  
Protein C ◽  
Receptor Gene ◽  
Activated Protein C ◽  
Soluble Form ◽  
Cell Protein ◽  
Endothelial Protein C Receptor ◽  
Thrombotic Risk ◽  
Increased Risk ◽  
The Relationship

SummaryEndothelial cell protein C receptor (EPCR) enhances the generation of activated protein C (APC) by the thrombin-thrombomodulin complex. A soluble form of EPCR (sEPCR), which is generated by metalloprotease activity, is present in plasma. The distribution of sEPCR levels in healthy populations is bimodal. Previously, we described two polymorphisms in exon 4 of the EPCR gene, 4600A/G that encodes the substitution of Ser219 by Gly in the transmembrane region of EPCR and 4678G/C in the 3’-UT region. The aim of this study was to investigate the relationship between these two polymorphisms and plasma sEPCR and APC levels and risk of venous thrombosis. We genotyped 401 healthy controls from the Spanish population and measured their plasma sEPCR and APC levels. Carriers of the 4600AG genotype had significantly higher sEPCR levels than those with the AA genotype, while the 4678CC genotype was associated, to a lesser extent, with elevated APC levels. To assess the effect of these polymorphisms on the risk of thrombosis, we genotyped 405 patients with venous thromboembolism. The frequency of the 4600AG genotype was very similar in patients and controls (p=0.975), whereas the 4678CC genotype was significantly more frequent in controls than in patients (p=0.008). In multivariate analysis, carriers of the 4678CC genotype had a decreased risk of thrombosis (OR=0.61, p=0.009). These data indicate that individuals carrying the 4600AG genotype have high sEPCR levels but do not have an increased risk of thrombosis, whereas individuals carrying the 4678CC genotype have higher APC levels and lower risk of venous thromboembolism.

Platelet factor 4 enhances generation of activated protein C in vitro and in vivo

Blood ◽  
2003 ◽  
Vol 102 (1) ◽  
pp. 146-151 ◽  
Author(s):  
Arne Slungaard ◽  
Jose A. Fernandez ◽  
John H. Griffin ◽  
Nigel S. Key ◽  
Janel R. Long ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Protein C ◽  
Umbilical Vein ◽  
Activated Protein C ◽  
Platelet Factor 4 ◽  
In Vivo Model ◽  
Platelet Factor ◽  
Umbilical Vein Endothelial Cells

Abstract Platelet factor 4 (PF4), an abundant platelet α-granule protein, accelerates in vitro generation of activated protein C (APC) by soluble thrombin/thrombomodulin (TM) complexes up to 25-fold. To test the hypothesis that PF4 similarly stimulates endothelium-associated TM, we assessed the influence of human PF4 on thrombin-dependent APC generation by cultured endothelial monolayers. APC generated in the presence of 1 to 100 μg PF4 was up to 5-fold higher than baseline for human umbilical vein endothelial cells, 10-fold higher for microvascular endothelial cells, and unaltered for blood outgrowth endothelial cells. In an in vivo model, cynomolgus monkeys (n = 6, each serving as its own control) were infused with either PF4 (7.5 mg/kg) or vehicle buffer, then with human thrombin (1.0 μg/kg/min) for 10 minutes. Circulating APC levels (baseline 3 ng/mL) peaked at 10 minutes, when PF4-treated and vehicle-treated animals had APC levels of 67 ± 5 ng/mL and 39 ± 2 ng/mL, respectively (P &lt; .001). The activated partial thromboplastin time (APTT; baseline, 28 seconds) increased maximally by 27 ± 6 seconds in PF4-treated animals and by 9 ± 1 seconds in control animals at 30 minutes (P &lt; .001). PF4-dependent increases in circulating APC and APTT persisted more than 2-fold greater than that of control's from 10 through 120 minutes (P ≤ .04). All APTT prolongations were essentially reversed by monoclonal antibody C3, which blocks APC activity. Thus, physiologically relevant concentrations of PF4 stimulate thrombin-dependent APC generation both in vitro by cultured endothelial cells and in vivo in a primate thrombin infusion model. These findings suggest that PF4 may play a previously unsuspected physiologic role in enhancing APC generation. (Blood. 2003;102:146-151)

scholarly journals Synthesis and Initial Pharmacology of Heterobivalent Ligands Targeting Putative Complexes of Integrin αVβ3 and PAR2

2019 ◽  
Author(s):  
Mark Majewski ◽  
Disha Gandhi ◽  
Trudy Holyst ◽  
Zhengli Wang ◽  
Irene Hernandez ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Protein C ◽  
Activated Protein C ◽  
Integrin Αvβ3 ◽  
Bivalent Ligands ◽  
Close Proximity ◽  
In Vitro Pharmacology ◽  
Protease Activated Receptor 2 ◽  
Related Pathway

Unpublished data from our labs led us to hypothesize that activated Protein C (aPC) may initiate an anti-inflammatory signal in endothelial cells by modulating both the integrin αVβ3 and Protease-Activated Receptor 2 (PAR2), which may exist in close proximity on the cellular surface. To test this hypothesis and to probe the possible inflammation-related pathway, we designed and synthesized heterobivalent ligands composed of modified versions of two αVβ3 ligands and two agonists of PAR2. These novel ligands were connected via copper-catalyzed alkyne-azide cycloadditions with polyethylene glycol (PEG) spacers of variable length. Initial in vitro pharmacology with EA.hy926 and HUVEC endothelial cells indicated that these bivalent ligands are effective binders of αVβ3 and potent agonists of PAR2. These bivalent ligands were also used in preliminary studies investigating their effects on PAR2 signaling in the presence of inflammatory agents, and represent the first examples of ligands targeting both PARs and integrins.

scholarly journals Synthesis and Initial Pharmacology of Heterobivalent Ligands Targeting Putative Complexes of Integrin αVβ3 and PAR2

2019 ◽  
Author(s):  
Mark Majewski ◽  
Disha Gandhi ◽  
Trudy Holyst ◽  
Zhengli Wang ◽  
Irene Hernandez ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Protein C ◽  
Activated Protein C ◽  
Integrin Αvβ3 ◽  
Bivalent Ligands ◽  
Close Proximity ◽  
In Vitro Pharmacology ◽  
Protease Activated Receptor 2 ◽  
Related Pathway

Unpublished data from our labs led us to hypothesize that activated Protein C (aPC) may initiate an anti-inflammatory signal in endothelial cells by modulating both the integrin αVβ3 and Protease-Activated Receptor 2 (PAR2), which may exist in close proximity on the cellular surface. To test this hypothesis and to probe the possible inflammation-related pathway, we designed and synthesized heterobivalent ligands composed of modified versions of two αVβ3 ligands and two agonists of PAR2. These novel ligands were connected via copper-catalyzed alkyne-azide cycloadditions with polyethylene glycol (PEG) spacers of variable length. Initial in vitro pharmacology with EA.hy926 and HUVEC endothelial cells indicated that these bivalent ligands are effective binders of αVβ3 and potent agonists of PAR2. These bivalent ligands were also used in preliminary studies investigating their effects on PAR2 signaling in the presence of inflammatory agents, and represent the first examples of ligands targeting both PARs and integrins.

scholarly journals Testing the effect of PAR1 inhibitors on Plasmodium falciparum-induced loss of endothelial cell barrier function

2020 ◽  
Vol 5 ◽  
pp. 34
Author(s):  
Janet Storm ◽  
Yang Wu ◽  
Jill Davies ◽  
Christopher A. Moxon ◽  
Alister G. Craig
Keyword(s):  
Endothelial Cells ◽  
Plasmodium Falciparum ◽  
Cerebral Malaria ◽  
Barrier Function ◽  
Protein C ◽  
Activated Protein C ◽  
Endothelial Activation ◽  
Endothelial Protein C Receptor ◽  
Barrier Dysfunction ◽  
Microvascular Endothelium

Background: Sequestration and cytoadherence of Plasmodium falciparum-infected erythrocytes (IE) to microvascular endothelium alters endothelial barrier function and plays a role in the pathogenesis of severe malaria. Binding of IE is mediated by P. falciparum erythrocyte membrane protein 1 (PfEMP1) and the PfEMP1 variants that binds to endothelial protein C receptor (EPCR) have, in particular, been associated with the dysregulation of the coagulation/inflammation pathways in endothelial cells. This has prompted speculation about the role of protease-activated receptor-1 (PAR1) activation and signalling in causing endothelial activation and loss of barrier function in cerebral malaria. Methods: We used a co-culture of primary human brain microvascular endothelial cells (HBMEC) with P. falciparum material, recombinant PfEMP1 or lysates from IE, and measured barrier function by trans endothelial electrical resistance (TEER).  A selection of PAR1 inhibitors was tested for their ability to reverse the P. falciparum and thrombin induced decrease in barrier function. Results: An initial screen in the presence of recombinant PfEMP1 identified a few inhibitors that were able to reduce the rapid thrombin-induced barrier disruption even when activated protein C (aPC) was unable to do so. However, PAR1 inhibitors did not rescue the barrier dysfunction after co-culture with IE lysate. Conclusions: The selected PAR1 inhibitors were able to reverse the disruption of barrier function by thrombin but did not reverse the IE lysate induced disruption of barrier function, implicating a different PAR1-independent mechanism.  These findings have implications for the design of adjunct therapies to reduce brain swelling in cerebral malaria.

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