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Taylor FB, He SE, Chang ACK, Box J, Ferrell G, Lee D, Lockhart M, Peer G, Esmon CT. Infusion of Phospholipid Vesicles Amplifies the Local Thrombotic Response to TNF and Anti-Protein C into a Consumptive Response. Thromb Haemost 2018. [DOI: 10.1055/s-0038-1650325] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
SummaryInflammation often is considered a contributing factor to both thrombosis and disseminated intravascular coagulation. The molecular mechanisms that dictate which of these clinical manifestations will result from the inflammatory stimulus remain obscure. Bacterial infection and certain tumors are common initiators of the disseminated intravascular coagulant response. Complement activation resulting from bacterial infection shares with selected tumors the capacity to generate or release membrane particles that lack functional adhesion receptors and hence could circulate to amplify a disseminated intravascular coagulant response. We developed a model of venous thrombosis that resulted in localized thrombus formation without disseminated intravascular coagulation. The model involves infusion of tumor necrosis factor, blockade of protein C and a partial decrease in venous flow caused by ligation of the superficial femoral vein without obstruction of the deep femoral vein. Infusion of phospholipid vesicles into this model resulted in amplification of a localized thrombotic response into a consumptive response.Seven different groups of animals were studied. The first three groups established the conditions necessary to produce deep vein thrombosis. The second four groups established the conditions necessary to produce disseminated intravascular coagulation. The infusion of phospholipid vesicles plus tumor necrosis factor and anti-protein C antibody resulted in consumption of fibrinogen, the production of thrombin/antithrombin complexes, a fall in platelet count, and venous thrombosis. Without ligation and catheterization phospholipid vesicles failed to produce the consumptive response. We conclude, therefore, that phospholipid vesicles can amplify a local thrombotic response into a consumptive response, and that vesiculation accompanying inflammation is one means by which localized coagulant activity may be amplified to produce disseminated intravascular coagulation.
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Affiliation(s)
- F B Taylor
- The Oklahoma Medical Research Foundation, Oklahoma City, USA
| | - S E He
- The Oklahoma Medical Research Foundation, Oklahoma City, USA
| | - A C K Chang
- University of Oklahoma Health Sciences Center, Oklahoma City, USA
| | - J Box
- Howard Hughes Medical Institute, Oklahoma City, USA
| | - G Ferrell
- The Oklahoma Medical Research Foundation, Oklahoma City, USA
| | - D Lee
- The Oklahoma Medical Research Foundation, Oklahoma City, USA
| | - M Lockhart
- The Oklahoma Medical Research Foundation, Oklahoma City, USA
| | - G Peer
- University of Oklahoma Health Sciences Center, Oklahoma City, USA
| | - C T Esmon
- The Oklahoma Medical Research Foundation, Oklahoma City, USA
- University of Oklahoma Health Sciences Center, Oklahoma City, USA
- Howard Hughes Medical Institute, Oklahoma City, USA
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Abstract
SummaryInflammation drives arterial, venous and microvascular thrombosis. Chronic inflammation contributes to arterial thrombotic complications, whereas acute inflammation drives venous thrombosis and microvascular thrombosis. Mechanistically, inflammation modulates thrombotic responses by upregulating procoagulants, downregulating anticoagulants and suppressing fibrinolysis. The inflammatory response can also result in cell apoptosis or necrosis. Products released from the dead cells, particularly histones, propagate further inflammation, tissue death and organ failure.Inhibition of histone mediated cytotoxicity appears to be a new mechanism for protecting against this deadly cascade.
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Taylor FB, Chang AC, Esmon CT, Hinshaw LB. Baboon model of Escherichia coli sepsis: description of its four stages and the role of tumor necrosis factor, tissue factors, and the protein C system in septic shock. Curr Stud Hematol Blood Transfus 2015:8-14. [PMID: 1954780 DOI: 10.1159/000419328] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- F B Taylor
- Oklahoma Medical Research Foundation, Oklahoma City
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Tamayo I, Velasco SE, Puy C, Esmon CT, Dichiara MG, Montes R, Hermida J. Group V secretory phospholipase A2 impairs endothelial protein C receptor-dependent protein C activation and accelerates thrombosis in vivo. J Thromb Haemost 2014; 12:1921-7. [PMID: 25069533 DOI: 10.1111/jth.12676] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 07/06/2014] [Indexed: 02/01/2023]
Abstract
BACKGROUND Endothelial protein C receptor (EPCR) must be bound to a molecule of phosphatidylcholine (PC) to be fully functional, i.e. to interact with protein C/activated protein C (APC) properly. PC can be replaced with other lipids, such as lysophosphatidylcholine or platelet-activating factor, by the action of group V secretory phospholipase A2 (sPLA2-V), an enzyme that is upregulated in a variety of inflammatory conditions. Studies in purified systems have demonstrated that the substitution of PC notably impairs EPCR function in a process called EPCR encryption. OBJECTIVES To analyze whether sPLA2-V was able to regulate EPCR-dependent protein C activation in vivo, and its impact on thrombosis and the hemostatic system. METHODS Mice were transfected with sPLA2-V by hydrodynamic gene delivery. The effects on thrombosis were studied with the laser carotid artery occlusion model, and APC generation capacity was measured with ELISA. Global hemostasis was analyzed with thromboelastometry. RESULTS We found that sPLA2-V overexpression in mice significantly decreased their ability to generate APC. Furthermore, a murine carotid artery laser thrombosis model revealed that higher sPLA2-V levels were directly associated with faster artery thrombosis. CONCLUSIONS sPLA2-V plays a thrombogenic role by impairing the ability of EPCR to promote protein C activation.
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Affiliation(s)
- I Tamayo
- Division of Cardiovascular Sciences, Laboratory of Thrombosis and Hemostasis, Center for Applied Medical Research, University of Navarra, Pamplona, Spain
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Semeraro F, Ammollo CT, Esmon NL, Esmon CT. Histones induce phosphatidylserine exposure and a procoagulant phenotype in human red blood cells. J Thromb Haemost 2014; 12:1697-702. [PMID: 25069624 PMCID: PMC4194154 DOI: 10.1111/jth.12677] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 07/17/2014] [Indexed: 11/29/2022]
Abstract
BACKGROUND Extracellular histones exert part of their prothrombotic activity through the stimulation of blood cells. Besides platelets, histones can bind to red blood cells (RBCs), which are important contributors to thrombogenesis, but little is known about the functional consequences of this interaction. OBJECTIVES To evaluate the effect of histones on the procoagulant potential of human RBCs with particular regard to the expression of surface phosphatidylserine (PS). METHODS PS exposure on human RBCs treated with a natural mixture of histones or recombinant individual histones was evaluated with fluorescein isothiocyanate-annexin-V binding and measured with flow cytometry. Calcium influx in RBCs loaded with the calcium-sensitive fluorophore Fluo-4 AM was assessed with flow cytometry. The procoagulant potential of histone-treated RBCs was evaluated with a purified prothrombinase assay and a one-stage plasma recalcification clotting test. RESULTS Natural histones induced PS exposure on RBCs in a dose-dependent manner, and neutralization or cleavage of histones by heparin or activated protein C, respectively, abolished PS externalization. H4 was mainly responsible for the stimulating activity of histones, whereas the other subtypes were almost ineffective. Similarly, natural histones and H4 induced influx of calcium into RBCs, whereas the other individual histones did not. Histone-induced exposure of PS on RBCs translated into increased prothrombinase complex-mediated prothrombin activation and accelerated fibrin formation in plasma. CONCLUSIONS Histones induce RBCs to express a procoagulant phenotype through the externalization of PS. This finding provides new insights into the prothrombotic activity of extracellular histones.
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Affiliation(s)
- F Semeraro
- Coagulation Biology Laboratory, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
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Sundaram J, Keshava S, Gopalakrishnan R, Esmon CT, Pendurthi UR, Rao LVM. Factor VIIa binding to endothelial cell protein C receptor protects vascular barrier integrity in vivo. J Thromb Haemost 2014; 12:690-700. [PMID: 24977291 PMCID: PMC4085578 DOI: 10.1111/jth.12532] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Recent studies have shown that factor VIIa binds to endothelial cell protein C receptor(EPCR), a cellular receptor for protein C and activated protein C. At present, the physiologic significance of FVIIa interaction with EPCR in vivo remains unclear. OBJECTIVE To investigate whether exogenously administered FVIIa, by binding to EPCR, induces a barrier protective effect in vivo. METHODS Lipopolysaccharide(LPS)-induced vascular leakage in the lung and kidney,and vascular endothelial growth factor (VEGF)-induced vascular leakage in the skin, were used to evaluate the FVIIa-induced barrier protective effect. Wild-type, EPCR-deficient, EPCR-overexpressing and hemophilia A mice were used in the studies. RESULTS Administration ofFVIIa reduced LPS-induced vascular leakage in the lung and kidney; the FVIIa-induced barrier protective effect was attenuated in EPCR-deficient mice. The extent of VEGF-induced vascular leakage in the skin was highly dependent on EPCR expression levels. Therapeutic concentrations of FVIIa attenuated VEGF-induced vascular leakage in control mice but not in EPCR-deficient mice.Blockade of FVIIa binding to EPCR with a blocking mAb completely attenuated the FVIIa-induced barrier protective effect. Similarly, administration of protease activated receptor 1 antagonist blocked the FVIIa induced barrier protective effect. Hemophilic mice showed increased vascular permeability, and administration of therapeutic concentrations of FVIIa improved barrier integrity in these mice. CONCLUSIONS This is the first study to demonstrate that FVIIa binding to EPCR leads to a barrier protective effect in vivo. This finding may have clinical relevance, as it indicates additional advantages of using FVIIa in treating hemophilic patients.
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Kager LM, Wiersinga WJ, Roelofs JJ, Meijers JCM, Zeerleder SS, Esmon CT, van't Veer C, van der Poll T. Endogenous protein C has a protective role during Gram-negative pneumosepsis (melioidosis). J Thromb Haemost 2013; 11:282-92. [PMID: 23216621 DOI: 10.1111/jth.12094] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 11/21/2012] [Indexed: 01/21/2023]
Abstract
BACKGROUND Activated protein C (APC) exerts anticoagulant effects via inactivation of factors Va and VIIIa and cytoprotective effects via protease activated receptor (PAR)1. Inhibition of endogenous APC in endotoxemia and sepsis results in exacerbation of coagulation and inflammation, with consequent enhanced lethality. OBJECTIVES We here sought to dissect the distinct roles of the anticoagulant and cytoprotective functions of endogenous APC in severe Gram-negative pneumonia-derived sepsis (melioidosis). METHODS We infected wild-type (WT) mice with Burkholderia pseudomallei, a common sepsis pathogen in southeast Asia, and treated them with antibodies inhibiting both the anticoagulant and cytoprotective functions of APC (MPC1609) or the anticoagulant functions of APC (MAPC1591) only. Additionally, we administered SEW2871 (stimulating the S1P1-pathway downstream from PAR1) to control and MPC1609-treated mice. RESULTS MPC1609, but not MAPC1591, significantly worsened survival, increased coagulation activation, facilitated bacterial growth and dissemination and enhanced the inflammatory response. The effects of MPC1609 could not be reversed by SEW2871, suggesting that S1P1 does not play a major role in this model. CONCLUSIONS These results suggest that the mere inhibition of the anticoagulant function of APC does not interfere with its protective role during Gram-negative pneumosepsis, suggesting a more prominent role for cytoprotective effects of APC .
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Affiliation(s)
- L M Kager
- Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
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Clark CA, Vatsyayan R, Hedner U, Esmon CT, Pendurthi UR, Rao LVM. Endothelial cell protein C receptor-mediated redistribution and tissue-level accumulation of factor VIIa. J Thromb Haemost 2012; 10:2383-91. [PMID: 22950420 PMCID: PMC3528836 DOI: 10.1111/j.1538-7836.2012.04917.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Accepted: 08/30/2012] [Indexed: 11/27/2022]
Abstract
BACKGROUND Recent studies show that activated factor VII (FVIIa) binds to the endothelial cell protein C receptor (EPCR) on the vascular endothelium; however, the importance of this interaction in hemostasis or pathophysiology is unknown. OBJECTIVE The aim of the present study was to investigate the role of the FVIIa interaction with EPCR on the endothelium in mediating FVIIa transport from the circulation to extravascular tissues. METHODS Wild-type, EPCR-deficient or ECPR-over-expressing mice were injected with human recombinant (r)FVIIa (120 μg kg(-1) body weight) via the tail vein. At varying time intervals after rFVIIa administration, blood and various tissues were collected to measure FVIIa antigen and activity levels. Tissue sections were analyzed by immunohistochemistry for FVIIa and EPCR. RESULTS The data reveal that, after intravenous (i.v.) injection, rFVIIa rapidly disappears from the blood and associates with the endothelium in an EPCR-dependent manner. Immunohistochemical analyses revealed that the association of FVIIa with the endothelium was maximal at 30 min and thereafter progressively declined. The FVIIa association with the endothelium was undetectable at time points exceeding 24 h post-FVIIa administration. The levels of rFVIIa accumulated in tissue correlate with expression levels of EPCR in mice and FVIIa associated with tissues remained functionally active for periods of at least 7 days. CONCLUSIONS The observation that an EPCR-dependent association of FVIIa with the endothelium is most pronounced soon after rFVIIa administration and subsequently declines temporally, combined with the retention of functionally active FVIIa in tissue homogenates for extended periods, indicates that FVIIa binding to EPCR on the endothelium facilitates the transport of FVIIa from circulation to extravascular tissues where TF resides.
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Affiliation(s)
- C A Clark
- Department of Cellular and Molecular Biology, Center for Biomedical Research, The University of Texas Health Science Center at Tyler, Tyler, TX, USA Department of Medicine, Malmö University Hospital, University of Lund, Malmö, Sweden Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Howard Hughes Medical Institute, Oklahoma City, OK, USA
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Abstract
Protein C and protein S are two plasma proteins that participate in an anticoagulant pathway. Protein C circulates as an inactive precursor that is converted to an active serine protease by a complex between thrombin and the endothelial cell-surface protein thrombomodulin. Activated protein C and protein S form an anticoagulant complex on cell surfaces that inactivates two of the regulatory proteins of coagulation, factors Va and VIIIa. Activated protein C is then cleared from the circulation by a relatively slow inactivation by α(1) antitrypsin and the protein C inhibitor. Deficiencies in protein C and protein S are associated with thrombotic complications. With protein S, this can arise as the result of a deficiency in protein S synthesis, proteolytic cleavage, and/or due to an increase in binding to the complement regulatory protein C4bBP, which behaves like an acute phase reactant. Inflammatory mediators not only elevate C4bBP levels, but also lead to downregulation of thrombomodulin expression. Animal experiments suggest that activated protein C and protein S may be effective and safe antithrombotic agents.
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Affiliation(s)
- C T Esmon
- Howard Hughes Medical Institute, Oklahoma Medical Research Foundation, and Departments of Pathology and Biochemistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Gopalakrishnan R, Pendurthi UR, Hedner U, Agersø H, Esmon CT, Rao LVM. Influence of endothelial cell protein C receptor on plasma clearance of factor VIIa. J Thromb Haemost 2012; 10:971-3. [PMID: 22372829 PMCID: PMC3883585 DOI: 10.1111/j.1538-7836.2012.04670.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Eid R, Huang H, Evankovich J, Nace G, Yan W, Xu J, Esmon CT, Tsung A. Extracellular histones function as alarmins in hepatic ischemia/reperfusion injury through toll-like receptor 9. J Am Coll Surg 2011. [DOI: 10.1016/j.jamcollsurg.2011.06.161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Ammollo CT, Semeraro F, Xu J, Esmon NL, Esmon CT. Extracellular histones increase plasma thrombin generation by impairing thrombomodulin-dependent protein C activation. J Thromb Haemost 2011; 9:1795-803. [PMID: 21711444 DOI: 10.1111/j.1538-7836.2011.04422.x] [Citation(s) in RCA: 264] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Histones are basic proteins that contribute to cell injury and tissue damage when released into the extracellular space. They have been attributed a prothrombotic activity, because their injection into mice induces diffuse microvascular thrombosis. The protein C-thrombomodulin (TM) system is a fundamental regulator of coagulation, particularly in the microvasculature, and its activity can be differentially influenced by interaction with several cationic proteins. OBJECTIVE To evaluate the effect of histones on the protein C-TM system in a plasma thrombin generation assay and in purified systems. METHODS The effect of histones on plasma thrombin generation in the presence or absence of TM was analyzed by calibrated automated thrombinography. Protein C activation in purified systems was evaluated by chromogenic substrate cleavage. The binding of TM and protein C to histones was evaluated by solid-phase binding assay. RESULTS Histones dose-dependently increased plasma thrombin generation in the presence of TM, independently of its chondroitin sulfate moiety. This effect was not caused by inhibition of activated protein C activity, but by the impairment of TM-mediated protein C activation. Histones were able to bind to both protein C and TM, but the carboxyglutamic acid domain of protein C was required for their effect. Histones H4 and H3 displayed the highest activity. Importantly, unlike heparin, DNA did not inhibit the potentiating effect of histones on thrombin generation. CONCLUSIONS Histones enhance plasma thrombin generation by reducing TM-dependent protein C activation. This mechanism might contribute to microvascular thrombosis induced by histones in vivo at sites of organ failure or severe inflammation.
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Affiliation(s)
- C T Ammollo
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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Schouten M, van't Veer C, Levi M, Esmon CT, van der Poll T. Endogenous protein C inhibits activation of coagulation and transiently lowers bacterial outgrowth in murine Escherichia coli peritonitis. J Thromb Haemost 2011; 9:1072-5. [PMID: 21251201 DOI: 10.1111/j.1538-7836.2011.04199.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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van Sluis GL, Brüggemann LW, Esmon CT, Kamphuisen PW, Richel DJ, Büller HR, van Noorden CJF, Spek CA. Endogenous activated protein C is essential for immune-mediated cancer cell elimination from the circulation. Cancer Lett 2011; 306:106-10. [PMID: 21420234 DOI: 10.1016/j.canlet.2011.02.038] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 02/21/2011] [Accepted: 02/23/2011] [Indexed: 01/05/2023]
Abstract
Fibrinogen and platelets play an important role in cancer cell survival in the circulation by protecting cancer cells from the immune system. Moreover, endogenous activated protein C (APC) limits cancer cell extravasation due to sphingosine-1-phosphate receptor-1 (S(1)P(1)) and VE-cadherin-dependent vascular barrier enhancement. We aimed to study the relative contribution of these two mechanisms in secondary tumor formation in vivo. We show that fibrinogen depletion limits pulmonary tumor foci formation in an experimental metastasis model in C57Bl/6 mice but not in NOD-SCID mice lacking a functional immune system. Moreover, we show that in the absence of endogenous APC, fibrinogen depletion does not prevent cancer cell dissemination and secondary tumor formation in immune-competent mice. Overall, we thus show that endogenous APC is essential for immune-mediated cancer cell elimination.
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Affiliation(s)
- G L van Sluis
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands
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Affiliation(s)
- C T Esmon
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Howard Hughes Medical Institute, and Departments of Pathology and Biochemistry & Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA.
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Xu J, Lupu F, Esmon CT. Inflammation, innate immunity and blood coagulation. Hamostaseologie 2010; 30:5-9. [PMID: 20162248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023] Open
Abstract
Inflammation drives arterial, venous and microvascular thrombosis. Chronic inflammation contributes to arterial thrombotic complications, whereas acute inflammation drives venous thrombosis and microvascular thrombosis. Mechanistically, inflammation modulates thrombotic responses by upregulating procoagulants, downregulating anticoagulants and suppressing fibrinolysis. The inflammatory response can also result in cell apoptosis or necrosis. Products released from the dead cells, particularly histones, propagate further inflammation, tissue death and organ failure. Inhibition of histone mediated cytotoxicity appears to be a new mechanism for protecting against this deadly cascade.
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Affiliation(s)
- J Xu
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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Delvaeye M, Noris M, De Vriese A, Esmon CT, Esmon NL, Ferrell G, Del-Favero J, Plaisance S, Claes B, Lambrechts D, Remuzzi G, Conway EM. Rare but Relevant Kidney Disorders. Clin J Am Soc Nephrol 2009. [DOI: 10.2215/01.cjn.0000927068.51205.29] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
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Grünfeld JP, Scholl UI, Bockenhauer D, Glaudemans B, van Bommel EF, Scheel PJ, Delvaeye M, Choi M, Liu T, Ramaekers VT, Häusler MG, Grimmer J, Tobe SW, Farhi A, Nelson-Williams C, Lifton RP, Feather S, Stanescu HC, Bandulik S, Zdebik AA, Reichold M, Tobin J, Lieberer E, Sterner C, Landoure G, Arora R, Sirimanna T, Thompson D, Cross JH, van't Hoff W, Al Masri O, Tullus K, Yeung S, Anikster Y, Klootwijk E, Hubank M, Dillon MJ, Heitzmann D, Arcos-Burgos M, Knepper MA, Dobbie A, Gahl WA, Warth R, Sheridan E, Kleta R, van der Wijst J, Scola R, Lorenzoni PJ, Heister A, van der Kemp A, Knoers NV, Hoenderop JG, Bindels RJ, Jansen I, Hendriksz TR, Aarnoudse AL, Feeley N, Noris M, De Vriese A, Esmon CT, Esmon NL, Ferrell G, Del-Favero J, Plaisance S, Claes B, Lambrechts D, Remuzzi G, Conway EM. Rare but Relevant Kidney DisordersSeizures, sensorineural deafness, ataxia, mental retardation, and electrolyte imbalance (SeSAME syndrome) caused by mutations in KCNJ10. Proc Natl Acad Sci U S A 106: 5842–5847, 2009Epilepsy, ataxia, sensorineural deafness, tubulopathy, and KCNJ10 mutations. N Engl J Med 360: 1960–1970, 2009A missense mutation in the Kv1.1 voltage-gated potassium channel-encoding gene KCNA1 is linked to human autosomal dominant hypomagnesemia. J Clin Invest 119: 936–942, 2009Idiopathic retroperitoneal fibrosis: Prospective evaluation of incidence and clinicoradiologic presentation. Medicine 88: 193–201, 2009Retroperitoneal fibrosis: The clinical, laboratory, and radiographic presentation. Medicine 88: 202–207, 2009Thrombomodulin mutations in atypical hemolytic-uremic syndrome. N Engl J Med 361: 345–357, 2009. Clin J Am Soc Nephrol 2009. [DOI: 10.2215/cjn.06710909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Xu J, Ji Y, Zhang X, Drake M, Esmon CT. Endogenous activated protein C signaling is critical to protection of mice from lipopolysaccaride-induced septic shock. J Thromb Haemost 2009; 7:851-6. [PMID: 19320827 DOI: 10.1111/j.1538-7836.2009.03333.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
SUMMARY BACKGROUND Activated protein C (APC) is known to protect animals from sepsis. Endogenous protein C is important in protection. It is unknown whether the cytoprotective or anticoagulant properties of protein C (PC) are responsible for the protective effect of endogenous PC. OBJECTIVE To determine if signaling by endogenous activated protein C contributes to survival in sepsis. METHODS We used an immunochemical approach to either block all of the known activities of protein C using mAb MPC1609 or, alternatively, selectively block the anticoagulant activity of activated protein C while sparing some of its cytoprotective activities using mAb MAPC1591. RESULTS MPC1609 blocked APC binding to endothelium whereas MAPC1591 enhanced binding. MPC1609 prevented APC protection of endothelial barrier function whereas MAPC1591 did not. Injection of MPC1609, but not MAPC1591, with a sublethal dose of lipopolysaccharide (LPS) caused lethality. At 18 h, the mice injected with MPC1609 plus LPS had much higher interleukin-6 (IL-6) levels than mice injected with LPS alone or LPS plus MPC1591. In these mice treated with LPS plus MPC1609, higher blood urea nitrogen (BUN) and creatinine levels suggested that an acute renal failure might contribute to a slow clearance of IL-6. CONCLUSIONS These studies demonstrate for the first time that cytoprotective activities of APC, and not the anticoagulant activity, is required for protection in this sepsis model. Similar anti-human antibodies may prove useful in clinical conditions such as trauma and hemophilia where cytoprotection is desirable, but the anticoagulant activity of endogenous activated protein C may contribute to bleeding.
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Affiliation(s)
- J Xu
- Cardiovascular Biology Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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Abstract
BACKGROUND Activated protein C (APC) significantly decreases mortality in severe sepsis, but its role in acute lung injury from non-infectious aetiologies is unclear. The role of APC in hyperoxic acute lung injury was tested by studying the physiology of lung injury development, measurement of key coagulation proteins and treatment with murine APC (mAPC). METHODS Mice were continuously exposed to >95% oxygen and lung injury was assessed by extravascular lung water, lung vascular protein permeability and alveolar fluid clearance. Coagulation proteins were measured in bronchoalveolar lavage (BAL) fluid and plasma. Recombinant mAPC was administered in preventive and treatment strategies. RESULTS Hyperoxia produced dramatic increases in lung vascular permeability and extravascular lung water between 72 and 96 h. Lung fluid balance was also adversely affected by progressive decreases in basal and cAMP-stimulated alveolar fluid clearance. Plasma levels of APC decreased at 72 h and were 90% depleted at 96 h. There were significant increases in BAL fluid levels of thrombomodulin, thrombin-antithrombin complexes and plasminogen activator inhibitor-1 at later time points of hyperoxia. Lung thrombomodulin expression was severely decreased during late hyperoxia and plasma levels of APC were not restored by excess thrombin administration. Administration of recombinant mAPC failed to improve indices of lung injury. CONCLUSIONS Hyperoxic acute lung injury produces procoagulant changes in the lung with a decrease in plasma levels of APC due to significant endothelial dysfunction. Replacement of mAPC failed to improve lung injury.
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Affiliation(s)
- M R Looney
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94143-0130, USA.
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Zheng X, Li W, Song Y, Hu Y, Ferrell GL, Esmon NL, Esmon CT. Non-hematopoietic EPCR regulates the coagulation and inflammatory responses during endotoxemia. J Thromb Haemost 2007; 5:1394-400. [PMID: 17445091 DOI: 10.1111/j.1538-7836.2007.02592.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Activated protein C (APC) protects the host from severe sepsis. Endothelial protein C receptor (EPCR) is expressed on both hematopoietic leukocytes and non-hematopoietic endothelium, and plays a key role in protein C activation. OBJECTIVES We explore the influence of EPCR deletion on the responses to lipopolysaccharide (LPS) and then determine whether the observed differences are due to loss of hematopoietic or non-hematopoietic EPCR. METHODS AND RESULTS After LPS challenge, EPCR null (Procr(-/-)) mice exhibited more thrombin and cytokine generation, neutrophil sequestration in the lung and a higher mortality rate than Procr(+/-) mice. Procr(+/-) BM/Procr(-/-) (non-hematopoietic Procr(-/-)) and Procr(-/-) BM/Procr(+/-) (hematopoietic Procr(-/-)) chimeric mice were generated by bone marrow (BM) transplantation. Compared with control Procr(+/-) mice, non-hematopoietic Procr(-/-) mice exhibited reduced protein C activation by thrombin and exaggerated responses to LPS challenge, whereas Procr(+/-) mice and hematopoietic Procr(-/-) mice exhibited similar protein C activation by thrombin and similar responses to LPS challenge. CONCLUSIONS EPCR deletion exaggerates the host responses to LPS primarily due to deficiency of EPCR on the non-hematopoietic cells.
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Affiliation(s)
- X Zheng
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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Abstract
Endothelial protein C receptor (EPCR) plays an important role in the protein C anticoagulation pathway. Previously, we have reported that EPCR can be shed from the cell surface, and that this is mediated by an unidentified metalloproteinase. In this study, we demonstrate that tumor necrosis factor-alpha converting enzyme/ADAM17 (TACE) is responsible for EPCR shedding. Phorbol-12-myristate 13-acetate (PMA)-stimulated EPCR shedding is reduced by approximately 50% in HEK293 cells transfected with human EPCR cDNA and by 60% in human umbilical vein endothelial cells after transfection of TACE small interfering RNA (siRNA) into these cells. PMA-stimulated EPCR shedding is completely blocked in fibroblasts from TACE-deficient mice transfected with human EPCR cDNA, and restored by transfection of TACE cDNA into this cell line. To characterize the EPCR sequence requirement for shedding, we generated several mutants of EPCR. Replacing amino acids from residue 193 to residue 200 with the FLAG sequence (DYKDDDDK) completely blocks EPCR shedding, whereas a single amino acid substitution in this region has less effect on EPCR shedding.
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Affiliation(s)
- D Qu
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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Qu D, Wang Y, Song Y, Esmon NL, Esmon CT. The Ser219-->Gly dimorphism of the endothelial protein C receptor contributes to the higher soluble protein levels observed in individuals with the A3 haplotype. J Thromb Haemost 2006; 4:229-35. [PMID: 16409473 DOI: 10.1111/j.1538-7836.2005.01676.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The endothelial cell protein C receptor (EPCR) plays an important role in regulating blood coagulation and in activated protein C-mediated anti-inflammatory and antiapoptotic processes. Recent studies reported that there are polymorphisms in the human EPCR gene. One of the polymorphisms (haplotype A3) results in substitution of the Ser at residue 219 with Gly in the transmembrane domain. This haplotype is associated with increased plasma levels of soluble EPCR and is a candidate risk factor for thrombosis. We established stable cell lines expressing either the EPCR A1 (Ser at residue 219) or A3 (Gly at residue 219) haplotype. Both constitutive and PMA-stimulated shedding are five- to sevenfold higher in the A3 cell line than the A1 cell line. We also isolated human umbilical vein endothelial cells (HUVEC) from A1/A1 or A1/A3 origins. PMA-stimulated shedding is fourfold higher in HUVEC derived from A1/A3 origin than from A1/A1 origin. After PMA treatment, the rate of human protein C activation decreased 36% in HUVEC derived from A1/A3 origin, while it only decreased 18% in HUVEC derived from A1/A1 origin. These results indicate that the A3 haplotype does promote cellular shedding in either 293 or endothelial cells and therefore is likely directly contributory to the higher soluble EPCR levels seen in patients carrying this haplotype.
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Affiliation(s)
- D Qu
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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25
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Affiliation(s)
- C T Esmon
- OK Med Res Fndn & Howard Hughes Med Inst, Cardiovascular Biology, Oklahoma City, OK 73104, USA.
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26
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Abstract
Coagulation is triggered by inflammatory mediators in a number of ways. However, to prevent unwanted clot formation, several natural anticoagulant mechanisms exist, such as the antithrombin-heparin mechanism, the tissue factor pathway inhibitor mechanism and the protein C anticoagulant pathway. This review examines the ways in which these pathways are down-regulated by inflammation, thus limiting clot formation and decreasing the natural anti-inflammatory mechanisms that these pathways possess.
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Affiliation(s)
- C T Esmon
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Howard Hughes Medical Institute, Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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Li W, Zheng X, Gu J, Hunter J, Ferrell GL, Lupu F, Esmon NL, Esmon CT. Overexpressing endothelial cell protein C receptor alters the hemostatic balance and protects mice from endotoxin. J Thromb Haemost 2005; 3:1351-9. [PMID: 15978090 DOI: 10.1111/j.1538-7836.2005.01385.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Previous studies have shown that blocking endothelial protein C receptor (EPCR)-protein C interaction results in about an 88% decrease in circulating activated protein C (APC) levels generated in response to thrombin infusion and exacerbates the response to Escherichia coli. To determine whether higher levels of EPCR expression on endothelial cells might further enhance the activation of protein C and protect the host during septicemia, we generated a transgenic mouse (Tie2-EPCR) line which placed the expression of EPCR under the control of the Tie2 promoter. The mice express abundant EPCR on endothelial cells not only on large vessels, but also on capillaries where EPCR is generally low. Tie2-EPCR mice show higher levels of circulating APC after thrombin infusion. Upon infusion with factor Xa and phospholipids, Tie2-EPCR mice generate more APC, less thrombin and are protected from fibrin/ogen deposition compared with wild type controls. The Tie2-EPCR animals also generate more APC upon lipopolysaccharide (LPS) challenge and have a survival advantage. These results reveal that overexpression of EPCR can protect animals against thrombotic or septic challenge.
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Affiliation(s)
- W Li
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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28
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Affiliation(s)
- C T Esmon
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA.
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Abstract
Systemic inflammation is a potent prothrombotic stimulus. Inflammatory mechanisms upregulate procoagulant factors, downregulate natural anticoagulants and inhibit fibrinolytic activity. In addition to modulating plasma coagulation mechanisms, inflammatory mediators appear to increase platelet reactivity. In vivo, however, natural anticoagulants not only prevent thrombosis, but they also dampen inflammatory activity. Some insights into the evolution and linkages between inflammatory mechanisms and the coagulation/anticoagulation mechanisms have become evident from recent structural studies. This review will summarize the interactions between inflammation and coagulation.
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Affiliation(s)
- C T Esmon
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA.
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30
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Liaw PCY, Ferrell G, Esmon CT. A monoclonal antibody against activated protein C allows rapid detection of activated protein C in plasma and reveals a calcium ion dependent epitope involved in factor Va inactivation. J Thromb Haemost 2003; 1:662-70. [PMID: 12871399 DOI: 10.1046/j.1538-7836.2003.00153.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Activated protein C (APC) serves as an 'on demand' anticoagulant. Defects in the APC anticoagulant pathway are underlying risk factors for the development of venous and arterial thrombosis. APC has recently been shown to significantly reduce mortality in patients with severe sepsis, presumably by virtue of its ability to down-regulate coagulation as well as inflammation. Our objective was to develop an assay that, for the first time, permits rapid detection of plasma APC. This assay will expedite studies of APC in a variety of vascular disease states including sepsis, severe atherosclerosis, diabetes, and vasculitis. By generating a highly APC-specific monoclonal antibody (HAPC 1555), we have developed an assay that, for the first time, allows rapid detection of plasma APC. The Kd measured for the interaction between APC and HAPC 1555 based on BIAcore studies and binding to immobilized HAPC on microtiter plates is 6.2 +/- 0.9 and 8.8 +/- 1.0 nmol L(-1), respectively. The interaction between HAPC 1555 and APC is Ca2+-dependent, with a Ca2+ concentration of 313 +/- 48 micro mol L(-1) required for half maximal binding. HAPC 1555 interferes with APC-mediated inactivation of factor (F)Va in the presence and absence of phospholipids, suggesting that HAPC 1555 binds to the FVa binding domain of APC. When HAPC 1555 was used in an APC enzyme capture assay, therapeutic APC levels could be measured in 1.5 h, and physiologic levels of APC could be detected between 3 and 19 h. APC levels were also shown to vary markedly in patients with severe sepsis. The rapidity of our APC assay makes APC detection in patients practical clinically. This assay will expedite studies of APC in a variety of vascular disease states including sepsis, severe atherosclerosis, diabetes, and vasculitis.
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Affiliation(s)
- P C Y Liaw
- Department of Medicine, Division of Hematology, McMaster University, and Howard Hughes Medical Institute, Oklahoma City, Oklahoma 73104, USA
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31
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Affiliation(s)
- C T Esmon
- Cardiovascular Biology Research Program, 825 NE 13th Street, Oklahoma City, OK 73104, USA.
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32
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Biguzzi E, Merati G, Liaw PC, Bucciarelli P, Oganesyan N, Qu D, Gu JM, Fetiveau R, Esmon CT, Mannucci PM, Faioni EM. A 23bp insertion in the endothelial protein C receptor (EPCR) gene impairs EPCR function. Thromb Haemost 2001; 86:945-8. [PMID: 11686350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
EPCR is a type I transmembrane protein, highly expressed on the endothelium of large vessels, that binds protein C and augments its activation. In this study, a 23bp insertion in the EPCR gene was found in 4/198 survivors of myocardial infarction and 3/194 patients with deep vein thrombosis. The EPCR gene with the insertion predicts a protein that lacks part of the extracellular domain, the transmembrane domain and the cytoplasmic tail. Expression studies showed that the truncated protein is not localized on the cell surface, cannot be secreted in the culture medium, and does not bind activated protein C. Since protein C activation depends on the concentration of EPCR, patients with the EPCR insertion could have a diminished protein C activation capacity. Further clinical studies of adequate samples size are necessary to establish whether or not the EPCR insertion predisposes to the development of thrombotic events.
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Affiliation(s)
- E Biguzzi
- Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, IRCCS Maggiore Hospital and University of Milano, Italy.
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33
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Abstract
The protease inhibitor ecotin fails to inhibit thrombin despite its broad specificity against serine proteases. A point mutation (M84R) in ecotin results in a 1.5 nM affinity for thrombin, 10(4) times stronger than that of wild-type ecotin. The crystal structure of bovine thrombin is determined in complex with ecotin M84R mutant at 2.5 A resolution. Surface loops surrounding the active site cleft of thrombin have undergone significant structural changes to permit inhibitor binding. Particularly, the insertion loops at residues 60 and 148 in thrombin, which likely mediate the interactions with macromolecules, are displaced when the complex forms. Thrombin and ecotin M84R interact in two distinct surfaces. The loop at residue 99 and the C-terminus of thrombin contact ecotin through mixed polar and nonpolar interactions. The active site of thrombin is filled with eight consecutive amino acids of ecotin and demonstrates thrombin's preference for specific features that are compatible with the thrombin cleavage site: negatively charged-Pro-Val-X-Pro-Arg-hydrophobic-positively charged (P1 Arg is in bold letters). The preference for a Val at P4 is clearly defined. The insertion at residue 60 may further affect substrate binding by moving its adjacent loops that are part of the substrate recognition sites.
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Affiliation(s)
- S X Wang
- Graduate Program in Chemistry and Chemical Biology, University of California, San Francisco, California 94143-0446, USA
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Faust SN, Levin M, Harrison OB, Goldin RD, Lockhart MS, Kondaveeti S, Laszik Z, Esmon CT, Heyderman RS. Dysfunction of endothelial protein C activation in severe meningococcal sepsis. N Engl J Med 2001; 345:408-16. [PMID: 11496851 DOI: 10.1056/nejm200108093450603] [Citation(s) in RCA: 422] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Impairment of the protein C anticoagulation pathway is critical to the thrombosis associated with sepsis and to the development of purpura fulminans in meningococcemia. We studied the expression of thrombomodulin and the endothelial protein C receptor in the dermal microvasculature of children with severe meningococcemia and purpuric or petechial lesions. METHODS We assessed the integrity of the endothelium and the expression of thrombomodulin and the endothelial protein C receptor in biopsy specimens of purpuric lesions from 21 children with meningococcal sepsis (median age, 41 months), as compared with control skin-biopsy specimens. RESULTS The expression of endothelial thrombomodulin and of the endothelial protein C receptor was lower in the patients with meningococcal sepsis than in the controls, both in vessels with thrombosis and in vessels without thrombosis. On electron microscopical examination, the endothelial cells were generally intact in both thrombosed and nonthrombosed vessels. Plasma thrombomodulin levels in the children with meningococcal sepsis (median, 6.4 ng per liter) were higher than those in the controls (median, 3.6 ng per liter; P=0.002). Plasma levels, protein C antigen, protein S antigen, and antithrombin antigen were lower than those in the controls. In two patients treated with unactivated protein C concentrate, activated protein C was undetectable at the time of admission, and plasma levels remained low. CONCLUSIONS In severe meningococcal sepsis, protein C activation is impaired, a finding consistent with down-regulation of the endothelial thrombomodulin-endothelial protein C receptor pathway.
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Affiliation(s)
- S N Faust
- Department of Paediatrics, Imperial College School of Medicine at St Mary's Hospital, London, United Kingdom
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35
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Abstract
Recent studies have focused on a myriad of mechanisms by which inflammation can potentiate blood clotting. Inflammatory mediators like endotoxin and tissue necrosis factor (TNF)-alpha can cause the expression of tissue factor on monocytes and, possibly, endothelium, thereby initiating the coagulation cascade. Activation of the complement system can lead to exposure of membrane surfaces capable of amplifying the initial tissue factor stimulus by facilitating the assembly of the factor VIIIa-factor IXa and the factor Xa-factor Va complexes. Inflammatory mediators, particularly interleukin-6, can also increase the levels of fibrinogen, an acute-phase reactant. In addition, the inflammatory mediators can elevate the levels of plasminogen activator inhibitor, thus suppressing the fibrinolytic system. These studies alone, however, do not prove that inflammation can trigger clinically relevant thrombus formation in vivo. For instance, TNF-alpha has been studied in cancer patients as a potential cure for cancer, and even though these patients are hypercoaguable, thrombosis was not commonly observed as a side effect of the near-lethal doses of TNF-alpha that were administered. Based on primate studies, inflammatory mediators like TNF-alpha can promote clot deposition effectively only if there is reduced flow and inhibition of the natural anticoagulant pathways. The requirement for multiple simultaneous injurious events probably explains why inflammation alone is not observed as a major cause of thrombosis.
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Affiliation(s)
- C T Esmon
- Oklahoma Medical Research Foundation, Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Okla., USA.
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36
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Esmon CT. Role of coagulation inhibitors in inflammation. Thromb Haemost 2001; 86:51-6. [PMID: 11487041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
It is becoming increasingly clear that coagulation augments inflammation and that anticoagulants, particularly natural anticoagulants, can limit the coagulation induced increases in the inflammatory response. The latter control mechanisms appear to involve not only the inhibition of the coagulation proteases, but interactions with the cells that either generate anti-inflammatory substances, such as prostacyclin, or limit cell activation. Recent studies have demonstrated a variety of mechanisms by which coagulation, particularly the generation of thrombin, factor Xa and the tissue factor-factor VIIa complex, can augment acute inflammatory responses. Many of these responses are due to the activation of one or more of the protease activated receptors. Activation of these receptors on endothelium can lead to the expression of adhesion molecules and platelet activating factor, thereby facilitating leukocyte activation. Therefore, anticoagulants that inhibit any of these factors would be expected to dampen the inflammatory response. The three major natural anticoagulant mechanisms seem to exert a further inhibition of these processes by impacting cellular responses. Antithrombin has been shown in vitro to increase prostacyclin responses and activated protein C has been shown to inhibit a variety of cellular responses including endotoxin induced calcium fluxes in monocytes and the nuclear translocation of NFKB, a key step in the generation of the inflammatory response. In some, but not all, in vivo models, these natural anticoagulants have been able to inhibit endotoxin/E. coli-mediated leukocyte activation and to diminish cytokine elaboration (TNF, IL-6 and IL-8). Phase III clinical studies for treatment of patients with severe sepsis have been completed for APC, which was successful (1), and for antithrombin, which was not (2). A phase III trial with tissue factor pathway inhibitor is in progress. In this review, the mechanisms by which the different natural anticoagulants are thought to function will be reviewed.
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Affiliation(s)
- C T Esmon
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104, USA.
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37
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Abstract
OBJECTIVE To review the physiologic and biochemical mechanisms that suggest that protein C and activated protein C (APC) have unique properties that make them good candidates for the treatment of microvascular thrombosis, disseminated intravascular coagulation, and sepsis. DATA SOURCES A summary of published medical literature from MEDLINE search files and published reviews on protein C physiology, biochemical properties, and activity in experimental and human sepsis. DATA SUMMARY Protein C is critical to the regulation of microvascular coagulation, as seen most clearly in humans born with congenital deficiency of protein C, who develop neonatal purpura fulminans. Protein C supplementation reverses the lesion formation. In primate models of sepsis, APC blocks disseminated intravascular coagulation initiated by Escherichia coli infusion, and inhibition of APC function exacerbates both the coagulant and inflammatory responses of the animals to sublethal levels of E. coli. In vitro experiments have shown that APC can inhibit neutrophil binding to selectins: Endothelial cell protein C receptor, a protein C/APC binding receptor, can bind to proteinase 3 bound to Mac-1 on leukocytes, potentially blocking tight leukocyte adhesion; and APC can inhibit tumor necrosis factor-alpha secretion by monocytes and other cell lines by interfering with nuclear factor-kappaB nuclear translocation. By blocking nuclear factor-kappaB nuclear translocation, cytokine- and endotoxin-mediated adhesion molecule up-regulation is decreased. These properties of APC are consistent with a large number of animal studies demonstrating that APC can diminish complications of crush injury and leukocyte damage to lung and other tissues in response to sepsis and decrease the inflammatory response. The animal studies are consistent with the phase 2 studies reported on APC use in the treatment of human sepsis. CONCLUSIONS The protein C pathway is uniquely poised to interfere with the microvascular coagulation and inflammation that follows challenge with endotoxin. By limiting leukocyte activation, cytokine elaboration, and microvascular coagulation, APC has been shown to prevent organ damage in experimental models of sepsis. These results are consistent with the initial phase 2 reports of APC therapy in human sepsis suggesting a clinical benefit and demonstrating anti-inflammatory activity with several reports of apparent protein C effectiveness in severe sepsis, especially meningococcemia.
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Affiliation(s)
- C T Esmon
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104, USA.
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Alberio L, Lämmle B, Esmon CT. Protein C replacement in severe meningococcemia: rationale and clinical experience. Clin Infect Dis 2001; 32:1338-46. [PMID: 11303270 DOI: 10.1086/319995] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2000] [Revised: 10/11/2000] [Indexed: 11/04/2022] Open
Abstract
Severe meningococcemia, which is associated with hemodynamic instability, purpura fulminans and disseminated intravascular coagulation, still has a high mortality rate, and patients who survive are often left invalids because of amputations and organ failure. Clinical studies have shown that levels of protein C are markedly decreased in patients with severe meningococcemia and that the extent of the decrease correlates with a negative clinical outcome. There is a growing body of data demonstrating that activated protein C, in addition to being an anticoagulant, is also a physiologically relevant modulator of the inflammatory response. The dual function of protein C may be relevant to the treatment of individuals with severe meningococcal sepsis. In the present review we give a basic overview of the protein C pathway and its anticoagulant activity, and we summarize experimental data showing that activated protein C replacement therapy clearly reduces the mortality rate for fulminant meningococcemia.
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Affiliation(s)
- L Alberio
- Central Haematology Laboratory, University Hospital Inselspital, Bern, Switzerland.
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39
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Esmon CT. Plasma glycolipids levels: new factors regulating the protein C anticoagulant pathway and determining thrombotic risk. Blood 2001; 97:1905. [PMID: 11264146 DOI: 10.1182/blood.v97.7.1905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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40
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Liaw PC, Mather T, Oganesyan N, Ferrell GL, Esmon CT. Identification of the protein C/activated protein C binding sites on the endothelial cell protein C receptor. Implications for a novel mode of ligand recognition by a major histocompatibility complex class 1-type receptor. J Biol Chem 2001; 276:8364-70. [PMID: 11099506 DOI: 10.1074/jbc.m010572200] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The endothelial cell protein C receptor (EPCR) is an endothelial cell-specific transmembrane protein that binds both protein C and activated protein C (APC). EPCR regulates the protein C anticoagulant pathway by binding protein C and augmenting protein C activation by the thrombin-thrombomodulin complex. EPCR is homologous to the MHC class 1/CD1 family, members of which contain two alpha-helices that sit upon an 8-stranded beta-sheet platform. In this study, we identified 10 residues that, when mutated to alanine, result in the loss of protein C/APC binding (Arg-81, Leu-82, Val-83, Glu-86, Arg-87, Phe-146, Tyr-154, Thr-157, Arg-158, and Glu-160). Glutamine substitutions at the four N-linked carbohydrate attachment sites of EPCR have little affect on APC binding, suggesting that the carbohydrate moieties of EPCR are not critical for ligand recognition. We then mapped the epitopes for four anti-human EPCR monoclonal antibodies (mAbs), two of which block EPCR/Fl-APC (APC labeled at the active site with fluorescein) interactions, whereas two do not. These epitopes were localized by generating human-mouse EPCR chimeric proteins, since the mAbs under investigation do not recognize mouse EPCR. We found that 5 of the 10 candidate residues for protein C/APC binding (Arg-81, Leu-82, Val-83, Glu-86, Arg-87) colocalize with the epitope for one of the blocking mAbs. Three-dimensional molecular modeling of EPCR indicates that the 10 protein C/APC binding candidate residues are clustered at the distal end of the two alpha-helical segments. Protein C activation studies on 293 cells that coexpress EPCR variants and thrombomodulin demonstrate that protein C binding to EPCR is necessary for the EPCR-dependent enhancement in protein activation by the thrombin-thrombomodulin complex. These studies indicate that EPCR has exploited the MHC class 1 fold for an alternative and possibly novel mode of ligand recognition. These studies are also the first to identify the protein C/APC binding region of EPCR and may provide useful information about molecular defects in EPCR that could contribute to cardiovascular disease susceptibility.
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Affiliation(s)
- P C Liaw
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA
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41
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Abstract
Endothelial cell protein C receptor (EPCR) augments protein C activation by the thrombin-thrombomodulin complex about 5-fold in vitro. Augmentation is EPCR concentration dependent even when the EPCR concentration is in excess of the thrombomodulin. EPCR is expressed preferentially on large blood vessel endothelium, raising questions about the importance of protein C-EPCR interaction for augmenting systemic protein C activation. In these studies, this question was addressed directly by infusing thrombin into baboons in the presence or absence of a monoclonal antibody to EPCR that blocks protein C binding. Activated protein C levels were then measured directly by capturing the enzyme on a monoclonal antibody and assaying with chromogenic substrate. Blocking protein C-EPCR interaction resulted in about an 88% decrease in circulating activated protein C levels generated in response to thrombin infusion. Leukocyte changes, fibrinogen consumption, fibrin degradation products, and vital signs were similar between the animals infused with thrombin alone and those infused with thrombin and the anti-EPCR antibody. The results indicate that EPCR plays a major role in protein C activation and suggest that defects in the EPCR gene might contribute to increased risk of thrombosis.
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Affiliation(s)
- F B Taylor
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104, USA
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42
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Abstract
Although lipid oxidation products are usually associated with tissue injury, it is now recognized that they can also contribute to cell activation and elicit anti-inflammatory lipid mediators. In this study, we report that membrane phospholipid oxidation can modulate the hemostatic balance. Oxidation of natural phospholipids results in an increased ability of the membrane surface to support the function of the natural anticoagulant, activated protein C (APC), without significantly altering the ability to support thrombin generation. Lipid oxidation also potentiated the ability of protein S to enhance APC-mediated factor Va inactivation. Phosphatidylethanolamine, phosphatidylserine, and polyunsaturation of the fatty acids were all required for the oxidation-dependent enhancement of APC function. A subgroup of thrombotic patients with anti-phospholipid antibodies specifically blocked the oxidation-dependent enhancement of APC function. Since leukocytes are recruited and activated at the thrombus or sites of vessel injury, our findings suggest that after the initial thrombus formation, lipid oxidation can remodel the membrane surface resulting in increased anticoagulant function, thereby reducing the thrombogenicity of the thrombus or injured vessel surface. Anti-phospholipid antibodies that block this process would therefore be expected to contribute to thrombus growth and disease.
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Affiliation(s)
- O Safa
- Department of Cardiovascular Biology, Oklahoma Medical Research Foundation, University of Oklahoma Health Sciences Center, Oklahoma City 73104, USA
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43
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Abstract
Thrombin is a multifunctional protein, with procoagulant, inflammatory and anticoagulant effects. Binding of thrombin to thrombomodulin results in activation of Protein C and initiation of the Activated Protein C anticoagulant pathway, a process that is augmented by the endothelial cell Protein C receptor (EPCR). Activated Protein C has demonstrated antithrombotic, anti-inflammatory, and profibrinolytic properties. Its antithrombotic activity is particularly important in the microcirculation, and Protein C deficiency is associated with microvascular thrombosis. Activated Protein C has also been shown to modulate inflammation. When the level of thrombomodulin or Protein C is reduced in sepsis there is a vicious cycle of coagulation and inflammation, with potentially lethal consequences. In vitro studies and animal models have shown that Activated Protein C blunts the inflammatory and coagulant response to sepsis through a variety of mechanisms.
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Affiliation(s)
- C T Esmon
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Howard Hughes Medical Institute, Oklahoma City 73104, USA.
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44
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Abstract
A solution structure for the complete zymogen form of human coagulation protein C is modeled. The initial core structure is based on the x-ray crystallographic structure of the gamma-carboxyglutamic acid (Gla)-domainless activated form. The Gla domain (residues 1-48) is modeled from the x-ray crystal coordinates of the factor VII(a)/tissue factor complex and oriented with the epidermal growth factor-1 domain to yield an initial orientation consistent with the x-ray crystal structure of porcine factor IX(a). The missing C-terminal residues in the light chain (residues 147-157) and the activation peptide residues 158-169 were introduced using homology modeling so that the activation peptide residues directly interact with the residues in the calcium binding loop. Molecular dynamics simulations (Amber-particle-mesh-Ewald) are used to obtain the complete calcium-complexed solution structure. The individual domain structures of protein C in solution are largely unaffected by solvation, whereas the Gla-epidermal growth factor-1 orientation evolves to a form different from both factors VII(a) and IX(a). The solution structure of the zymogen protein C is compared with the crystal structures of the existing zymogen serine proteases: chymotrypsinogen, proproteinase, and prethrombin-2. Calculated electrostatic potential surfaces support the involvement of the serine protease calcium ion binding loop in providing a suitable electrostatic environment around the scissile bond for II(a)/thrombomodulin interaction.
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Affiliation(s)
- L Perera
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA.
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45
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Kurosawa S, Esmon CT, Stearns-Kurosawa DJ. The soluble endothelial protein C receptor binds to activated neutrophils: involvement of proteinase-3 and CD11b/CD18. J Immunol 2000; 165:4697-703. [PMID: 11035113 DOI: 10.4049/jimmunol.165.8.4697] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The protein C pathway is a primary regulator of blood coagulation and a critical component of the host response to inflammatory stimuli. The most recent member of this pathway is the endothelial protein C receptor (EPCR), a type I transmembrane protein with homology to CD1d/MHC class I proteins. EPCR accelerates formation of activated protein C, a potent anticoagulant and antiinflammatory agent. The current study demonstrates that soluble EPCR binds to PMA-activated neutrophils. Using affinity chromatography, binding studies with purified components, and/or blockade with specific Abs, it was found that soluble EPCR binds to proteinase-3 (PR3), a neutrophil granule proteinase. Furthermore, soluble EPCR binding to neutrophils was partially dependent on Mac-1 (CD11b/CD18), a beta(2) integrin involved in neutrophil signaling, and cell-cell adhesion events. PR3 is involved in multiple diverse processes, including hemopoietic proliferation, antibacterial activity, and autoimmune-mediated vasculitis. The observation that soluble EPCR binds to activated neutrophils via PR3 and a beta(2) integrin suggests that there may be a link between the protein C anticoagulant pathway and neutrophil functions.
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Affiliation(s)
- S Kurosawa
- Cardiovascular Biology Research, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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46
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Abstract
Among the mechanisms suggested for the prothrombotic activity of lupus anticoagulant and antiphospholipid antibodies is the direct inhibition of the anticoagulant activated protein C (APC) pathway. Although some pathological antibodies may be directed towards the proteins involved, we hypothesize that populations exist which selectively inhibit the APC complex as a result of differences in the phospholipid requirements of this complex as compared to those of the procoagulant complexes. The most prominent feature is the requirement for the presence of phosphatidylethanolamine in the membrane for APC anticoagulant function. This mimics the requirements for inhibitory activity of at least a subset of autoantibodies associated with thrombosis. The role of oxidation of the phospholipid in APC function and antibody reactivity is also discussed.
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Affiliation(s)
- N L Esmon
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma University Health Sciences Center, Oklahoma City, 73104, USA.
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47
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Abstract
Recent research has revealed a number of links between inflammation and coagulation. The protein C anticoagulant pathway appears to be the major pathway involved in the cross-talk between inflammation and coagulation. Studies indicate that inflammatory mediators can downregulate key components of the pathway through transcriptional control, proteolytic inactivation and oxidant damage. In turn, in vivo and in vitro studies have revealed mechanisms by which the components of the pathway may inhibit inflammatory responses. These include inhibition of cytokine responses to endotoxin, inhibition of leukocyte attachment to the activated endothelium and inhibition of thrombin and factor Xa generation in the microcirculation where both enzymes can lead to endothelial cell activation, further potentiating the inflammatory response. The ability of the protein C system to modulate both inflammation and coagulation may explain i part why specific defects in the pathway appear to be associated with both arterial and venus thrombosis.
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Affiliation(s)
- C T Esmon
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Department of Pathology, University of Oklahoma Health Sciences Center and Howard Hughes Medical Institute, Oklahoma City, OK 73104, USA.
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48
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Esmon CT. The endothelial cell protein C receptor. Thromb Haemost 2000; 83:639-43. [PMID: 10823253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- C T Esmon
- Oklahoma Medical Research Foundation, Department of Pathology and Biochemistry, University of Oklahoma Health Science Center, Oklahoma City 73104, USA.
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49
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Abstract
The protein C pathway plays a critical role in the negative regulation of blood coagulation. The nucleotide sequence of the murine endothelial protein C receptor (mEPCR) gene was determined for 8.8 kilobase pairs of the genomic structure and 3.4 kilobase pairs of the 5'-flanking region. RNase protection assay revealed six major transcription start sites clustered at -100 to -109 upstream of the translation initiation site. A series of 5'-promoter deletion fragments were fused to a luciferase reporter gene and transiently transfected into bovine aortic endothelium. Deletion of the sequence from -220 to -180 dramatically reduced luciferase expression in bovine aortic endothelial cells. This region of the murine endothelial protein C receptor gene contains one AP4 site and one SP1 site. Mutations in the core sequence of the AP4 and SP1 sites impaired both nuclear protein binding and luciferase expression. These results suggest important roles for AP4 and SP1 in the constitutive expression of mEPCR. A thrombin response element (CCCACCCC) was found to mediate the induction of mEPCR by thrombin in cell culture. Transgenic mice were developed expressing green fluorescent protein driven by the -350 to -1 or -1080 to -1 promoter. Thrombin up-regulated mEPCR and the transgene in vivo.
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Affiliation(s)
- J M Gu
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA
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50
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Abstract
The protein C anticoagulant pathway converts the coagulation signal generated by thrombin into an anticoagulant response through the activation of protein C by the thrombin-thrombomodulin (TM) complex. The activated protein C (APC) thus formed interacts with protein S to inactivate two critical coagulation cofactors, factors Va and VIIIa, thereby dampening further thrombin generation. The proposed mechanisms by which TM switches the specificity of thrombin include conformational changes in thrombin, blocking access of normal substrates to thrombin and providing a binding site for protein C. The function of protein S appears to be to alter the cleavage site preferences of APC in factor Va, probably by changing the distance of the active site of APC relative to the membrane surface. The clinical relevance of this pathway is now established through the identification of deficient individuals with severe thrombotic complications and through the analysis of families with partial deficiencies in these components and an increased thrombotic tendency. One possible reason that even partial deficiencies are a thrombotic risk is that the function of the pathway can be down-regulated by inflammatory mediators. For instance, clinical studies have shown that the extent to which protein C levels decrease in patients with septic shock is predictive of a negative outcome. Initial clinical studies suggest that supplementation with protein C may be useful in the treatment of acute inflammatory diseases such as sepsis.
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Affiliation(s)
- C T Esmon
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA.
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