(Chest. 2003;124:26S-32S.)
© 2003
American College of Chest Physicians
The Protein C Pathway*
Charles T. Esmon, PhD
* Investigator, Howard Hughes Medical Institute, Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK.
Correspondence to: Charles T. Esmon, PhD, Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, 825 NE 13th St, Oklahoma City, OK 73104; e-mail: Charles-Esmon{at}omrf.ouhsc.edu
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Abstract
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The protein C anticoagulant pathway serves as a major system for controlling thrombosis, limiting inflammatory responses, and potentially decreasing endothelial cell apoptosis in response to inflammatory cytokines and ischemia. The essential components of the pathway involve thrombin, thrombomodulin, the endothelial cell protein C receptor (EPCR), protein C, and protein S. Thrombomodulin binds thrombin, directly inhibiting its clotting and cell activation potential while at the same time augmenting protein C (and thrombin activatable fibrinolysis inhibitor [TAFI]) activation. Furthermore, thrombin bound to thrombomodulin is inactivated by plasma protease inhibitors > 20 times faster than free thrombin, resulting in increased clearance of thrombin from the circulation. The inhibited thrombin rapidly dissociates from thrombomodulin, regenerating the anticoagulant surface. Thrombomodulin also has direct anti-inflammatory activity, minimizing cytokine formation in the endothelium and decreasing leukocyte-endothelial cell adhesion. EPCR augments protein C activation approximately 20-fold in vivo by binding protein C and presenting it to the thrombin-thrombomodulin activation complex. Activated protein C (APC) retains its ability to bind EPCR, and this complex appears to be involved in some of the cellular signaling mechanisms that down-regulate inflammatory cytokine formation (tumor necrosis factor, interleukin-6). Once APC dissociates from EPCR, it binds to protein S on appropriate cell surfaces where it inactivates factors Va and VIIIa, thereby inhibiting further thrombin generation. Clinical studies reveal that deficiencies of protein C lead to microvascular thrombosis (purpura fulminans). During severe sepsis, a combination of protein C consumption, protein S inactivation, and reduction in activity of the activation complex by oxidation, cytokine-mediated down-regulation, and proteolytic release of the activation components sets in motion conditions that would favor an acquired defect in the protein C pathway, which in turn favors microvascular thrombosis, increased leukocyte adhesion, and increased cytokine formation. APC has been shown clinically to protect patients with severe sepsis. Protein C and thrombomodulin are in early stage clinical trials for this disease, and each has distinct potential advantages and disadvantages relative to APC.
Key Words: endothelial cell protein C receptor • endothelium • leukocytes • protein C • sepsis • thrombin • thrombosis
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The Activation Complex
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The key feature of the protein C pathway resides in the ability of the pathway to respond to the presence of thrombin. As the thrombin concentration rises, much of the thrombin binds to thrombomodulin, primarily on the endothelial cell surface (Fig 1 ), leading to the activation of protein C.
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Figure 1.. The role of the protein C pathway in regulating coagulation. Endotoxin leads to initiation by a variety of mechanisms, primarily by eliciting tissue factor expression. This leads to formation of factor VIIIa-IXa complexes and factor Va-Xa, and ultimately to thrombin generation. Thrombin can either cause fibrin formation and platelet and endothelial cell activation, or it can bind to thrombomodulin (TM), where it rapidly activates protein C. This process is enhanced by the EPCR. Once APC dissociates from EPCR, it binds to protein S, and this complex then inactivates factors Va and VIIIa. In the case of factor VIIIa, the process is enhanced further by factor V.1
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Protein C activation is enhanced approximately 20-fold in vivo when protein C is bound to the endothelial cell protein C receptor (EPCR).2
Relative to free thrombin, thrombin bound to thrombomodulin is inactivated much more rapidly by antithrombin and the protein C inhibitor, with an estimated half-life for inactivation of approximately 2 s.3
Thus, once thrombin generation ceases, the protein C activation complex quickly stops generating activated-protein C (APC).
Protein C and APC bind to EPCR with equal affinity. By having EPCR participate in protein C activation, it guarantees that EPCR will be "loaded" with APC. APC bound to EPCR can be inactivated by plasma protease inhibitors (
1-antitrypsin and protein C inhibitor) at approximately the same rate as free APC (half-times approximately 15 min).4
This slow inactivation allows APC bound to EPCR to signal cells. Cleavage of protease-activated receptor (PAR)-1 by the APC-EPCR complex has been implicated as one such cell-signaling mechanism, the most important of which seems to be related to antiapoptotic activities.5
6
In addition to activating protein C, the thrombin-thrombomodulin complex is a potent activator of thrombin activatable fibrinolysis inhibitor (TAFI),7
a procarboxypeptidase B. This enzyme removes terminal Arg and Lys residues. In the case of fibrin, removal of the Lys residues slows clot lysis (see the article by Dr. Nesheim in this supplement). Carboxypeptidase B activity, however, has long been recognized for being involved in the inactivation of vasoactive substances like the anaphylatoxin C5a generated during complement activation. TAFI has been found to be the most effective inhibitor of C5a,8
9
potentially protecting the microvasculature from injury in infectious diseases and in mismatched transfusions where complement activation is triggered.
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Other Functions of the Activation Complex
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Thrombomodulin is a complex molecule with multiple distinct domains (Fig 2
). Different functions have been ascribed to these domains. The N-terminal domain has sequence similarity to the lectins, which are carbohydrate-binding proteins, and is not involved in protein C activation. The lectin domain has been shown to have anti-inflammatory activity.10
Whether infused, added as the soluble isolated domain, or present on cellular thrombomodulin (ie, native), the presence of the domain down-regulates nuclear factor-
B and mitogen-activated protein (MAP) kinase pathways, which are involved in endothelial cell activation and in setting the stage for endothelial cell dysfunction. Presumably, a signaling receptor on endothelium is either blocked by the lectin domain or turned on to send negative regulatory signals by lectin-domain engagement. Since the MAP kinase pathway is down-regulated in a variety of disease states, this anti-inflammatory activity would become diminished, rendering the vasculature vulnerable to further injury.
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Figure 2.. Thrombin binding to thrombomodulin involves anion-binding exosite 1 on thrombin (shown as a strip through the middle of thrombin) and EGF domains 4 to 6 on thrombomodulin. A chondroitin sulfate moiety on thrombomodulin increases the affinity for thrombin, but is not required for function. This chondroitin sulfate interacts with anion-binding exosite 2 on thrombin, a second, very basic area near the heparin-binding site. As shown by Conway et al,10
the lectin domain of thrombomodulin inhibits leukocyte adhesion and the MAP kinase pathway. Other functions of thrombomodulin require the presence of different EGF domains as indicated. The activation of protein C to APC by the thrombin-thrombomodulin complex is enhanced by binding of protein C to EPCR through its gla domain.15
See Figure 1
legend for expansion of abbreviation.
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In addition to being involved in protein C and TAFI activation, the epidermal growth factor (EGF) domains of thrombomodulin have been shown to have growth mitogenic activity on fibroblasts,11
suggesting a role in wound healing and possible development of atherosclerosis. Activation of TAFI requires EGF domains 3 to 6, whereas the activation of protein C requires only EGF domains 4 to 6.12
Immediately above the membrane is a region heavily modified with O-linked sugars and often modified with a chondroitin sulfate. When modified with the chondroitin sulfate, thrombomodulin binds thrombin about 10 times tighter and accelerates inactivation of bound thrombin by antithrombin and protein C inhibitor.3
13
14
Available information indicates that not all human thrombomodulin molecules have the chondroitin sulfate moiety and the relative extent of the modification in different vascular beds is unknown.
The EPCR is structurally very similar to the major histocompatibility class 1/CD1 family of molecules (Fig 3
),15
16
almost all of which are involved in immunity/inflammation. In the case of the CD1 family, these molecules have been shown to bind glycolipids and present glycolipid antigens to T cells to elicit immune reactions involved in protecting the body from bacterial invasion, as in tuberculosis.17
They can also be involved in preventing autoimmunity, including antiphospholipid syndrome.18
Like the CD1 family members, EPCR has a lipid, in this case phospholipid, bound in the "antigen-presenting" groove.
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Figure 3.. The recombinant soluble (rs)EPCR molecule with a portion of the protein C Gla domain and a lipid molecule. In EPCR (yellow ribbon), two -helices and an eight-stranded ß sheet create a groove that is filled with phospholipid (the space-filling balls in the center). Binding of Ca2+ ions (magenta spheres) to the protein C Gla domain (green ribbon) exposes the N-terminal "omega" loop, which in the absence of EPCR interacts with the phospholipid surfaces on the membrane. There do not appear to be direct interactions between the protein C Gla domain and the lipid molecule located in the groove of rsEPCR. The model of the complex consists of residues 7 to 177 of rsEPCR and the first 33 residues of the protein C Gla domain.
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The lipid is necessary for tight protein binding, but its role in the immune reactions associated with bacterial challenge remain unknown. It is known, however, that blocking protein C/APC binding to EPCR exacerbates the inflammatory (increased interleukin [IL]-6) and coagulant (greater decrease in fibrinogen and increase in d-dimer) responses of baboons to challenge by low-dose Escherichia coli infusion.19
Interaction with leukocytes is another observation linking EPCR to the regulation of the inflammatory response. Soluble EPCR is released from endothelium through the action of a metalloproteinase. This enzyme is activated in response to IL-1ß, thrombin, or phorbol myristate acetate stimulation of the endothelium.20
Clinically, the levels of soluble receptor seem to increase in patients with lupus erythematosus or sepsis.21
Soluble EPCR binds to activated neutrophils in a process that involves binding directly to leukocyte-derived proteinase 3,22
the autoantigen in Wegener granulomatosis. Proteinase 3 in turn binds to Mac-1 (CD11b/CD18), a leukocyte integrin involved in tight leukocyte attachment to activated endothelium. Available data suggest that EPCR may block tight attachment of leukocytes by blocking these integrin interactions.23
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Functions of APC
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In addition to inactivating factors Va and VIIIa (Fig 1)
,24
25
APC has been shown to have anti-inflammatory, antiapoptotic, and anticoagulant activity at the cellular level. The antiapoptotic activity appears to be mediated, at least in part, by the APC-EPCR complex cleaving PAR-1. Since EPCR is expressed primarily on endothelium,26
but PAR is located on many cells, the EPCR dependence probably allows for preferential activation of this receptor on endothelium,5
thereby avoiding platelet and neutrophil activation that might otherwise occur. The antiapoptotic activity of APC mediated through PAR-1 activation is supported by the recent observation that either APC (in an EPCR-dependent fashion) or PAR-1 activation peptides could protect mice from ischemic stroke.6
APC activation of PAR-1 would not appear to account for other cellular responses associated with APC treatment in vivo or with cells. APC has been shown to inhibit tumor necrosis factor (TNF)- release in vivo,27
28
TNF- release from monocytes,29
and nuclear factor-B nuclear translocation. In addition, APC has been shown repeatedly to block leukocyte adhesion in vivo, something that PAR-1 activation should increase. Finally, APC has been reported to inhibit tissue factor expression, which PAR-1 activation increases.30
Thus, at present, there appears to be more than one APC signaling molecule, the others most likely responsible for the anti-inflammatory activities.
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Physiology of the Protein C Pathway
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Thrombomodulin is located on the endothelium; in general, the number of copies per endothelial cell appear by immunohistochemistry to vary < 10-fold among vascular beds (the brain microcirculation being an exception, where thrombomodulin expression is very low).31
From simple geometry, the endothelial cell to blood volume ratio increases hundreds of fold as blood moves from the large vessels to the capillaries. Assuming 100,000 copies of thrombomodulin per endothelial cell, a reasonable estimate of the thrombomodulin concentration in the capillaries is in the range of 100 to 500 nmol/L. Thrombomodulin binds thrombin with a Kd approximately 1 to 10 nmol/L depending on the presence of the chondroitin sulfate. Therefore, as thrombin passes through microvascular beds, the high concentrations of thrombomodulin will tend to remove almost all of the thrombin, leading to rapid thrombin inactivation by inhibitors, direct blockage of thrombin procoagulant reactions, and rapid activation of protein C.13
32
33
Consistent with this concept, severe defects in the protein C pathway are associated with microvascular thrombosis, particularly of the skin (purpura fulminans). In the case of protein C deficiency, progression and reversal (assuming no tissue death) of these lesions can be prevented and reversed rapidly by administration of protein C.34
These lesions look similar to those that can appear in septic patients, particularly patients with meningococcemia, where protein C supplementation appears to halt lesion progression.35
36
37
Although no randomized clinical studies of protein C in severe sepsis have been performed, the authors of the above studies suggested that the clinical outcome in terms of survival was considerably better than would be predicted from historical controls.
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Regulation of the Protein C Pathway
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Down-regulation
Both thrombomodulin and EPCR can be down-regulated at the transcriptional level by inflammatory cytokines like IL-1ß and TNF-.16
38
In addition, thrombomodulin activity can be dramatically reduced by oxidants released from leukocytes.39
Finally, leukocyte elastase rapidly releases soluble forms of thrombomodulin40
that have considerably less activity than the cellular form because they no longer have the EPCR acceleration effect and they do not contain the chondroitin for high-affinity thrombin binding.
The net effect of this inflammatory attack on the vessel wall is to decrease protein C activation and thrombomodulin expression. This has been shown in a subgroup of patients with meningococcemia,41
and direct assays of APC levels in patients with severe sepsis show a considerable range of protein C activation dysfunction.42
Thrombin and IL-1ß can lead to release of soluble EPCR, decreasing the protein C activation potential.20
In the case of thrombin, however, this is offset by a thrombin-dependent increase in EPCR gene transcription.43
Cellularly released proteins can also inhibit protein C activation. Eosinophil major basic protein is a potent inhibitor of thrombomodulin-dependent protein C activation,44
potentially contributing to thrombosis in hypereosinophilic heart disease.
Up-regulation
Platelet factor 4 has been shown to increase protein C activation rates approximately fourfold in vitro.45
Release of platelet factor 4 from platelets at sites of vascular injury provides a potential mechanism for limiting thrombus growth downstream of the injury site.
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The Protein C Pathway in Sepsis
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The combined anticoagulant and anti-inflammatory activities of APC have been recognized for a long time as an attractive combination for treating severe sepsis. In initial studies in baboons, APC was shown to prevent death from infusion of normally lethal concentrations of E coli. APC infusion was associated with a reduced drop in BP, decreased markers of inflammation, and a decreased coagulant response.46
When endogenous protein C activation was prevented, the animals responded to low-level E coli infusion as if they had received a toxic dose. Furthermore, blocking APC function in this low-level infusion model increased both the coagulant and inflammatory (TNF-) responses. These experiments suggest that an effective protein C system plays a critical role in the host defense against sepsis. These predictions were confirmed in a large clinical trial of APC for the treatment of patients with severe sepsis,47
in which patients receiving APC had a 19.4% reduction in the relative risk of death compared to placebo-treated subjects. Bleeding, particularly intracranial bleeding, is a major concern with anticoagulant treatment in septic patients. In this trial, two patients receiving APC had intracranial bleeds compared to one patient in the placebo group. It appears that the bleeds that were observed may be more common in patients with very low platelet counts. This may be because in addition to the role of platelets in primary hemostasis, platelets have approximately 25% of the total factor V in humans, and the factor V/Va on the platelet surface is relatively resistant to inactivation by APC.48
Currently, at least three different approaches to the treatment of sepsis and disseminated intravascular coagulation are under consideration using the protein C pathway. From a theoretical perspective, these approaches have different strengths and weaknesses. Based on available information, these are outlined in Table 1 .49
50
Down-regulation of the protein C pathway is not restricted to sepsis. Decreased thrombomodulin and/or EPCR expression has been observed in diabetes (rats),51
vein bypass grafts (rabbits),52
atherosclerosis (humans),53
and vasculitities (humans).54
A critical role for thrombomodulin in vascular injury can be inferred from gene transfer experiments. In rabbits, deep arterial injury is associated with leukocyte infiltration, thrombosis, and restenosis. In rabbits treated with adenovirus driving thrombomodulin expression, all of these events were inhibited.55
The control virus treatment was not protective.
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Summary
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The protein C pathway is important for the negative control of both coagulation and inflammation. The recently described inhibition of apoptosis by APC may be particularly important in the treatment of ischemic diseases. Modulation of the pathway can be therapeutically beneficial. Furthermore, the pathway may be down-regulated in a variety of disease states to such an extent that the down-regulation contributes to the severity of the disease. Future studies will likely provide new methods to modulate this system in the treatment of a wide variety of vascular and inflammatory diseases.
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Footnotes
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Abbreviations: APC = activated protein C; EGF = epidermal growth factor; EPCR = endothelial cell protein C receptor; IL = interleukin; MAP = mitogen-activated protein; PAR = protease activated receptor; TAFI = thrombin activatable fibrinolysis inhibitor; TNF = tumor necrosis factor
Dr. Esmon holds patents and licenses related to the use of protein C and activated protein C in the treatment of sepsis and thrombosis, as well as patents related to diagnostic aspects of defects in the protein C pathway.
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References
|
|---|
- Shen, L, Dahlback, B (1994) Factor V and protein S as synergistic cofactors to activated protein C in degradation of factor VIIIa. J Biol Chem 269,18735-18738[Abstract/Free Full Text]
- Taylor, FB, Jr, Peer, GT, Lockhart, MS, et al Endothelial cell protein C receptor plays an important role in protein C activation in vivo. Blood 2001;97,1685-1688[Abstract/Free Full Text]
- Rezaie, AR, Cooper, ST, Church, FC, et al Protein C inhibitor is a potent inhibitor of the thrombin-thrombomodulin complex. J Biol Chem 1995;270,25336-25339[Abstract/Free Full Text]
- Regan, LM, Stearns-Kurosawa, DJ, Kurosawa, S, et al The endothelial cell protein C receptor: inhibition of activated protein C anticoagulant function without modulation of reaction with proteinase inhibitors. J Biol Chem 1996;271,17499-17503[Abstract/Free Full Text]
- Riewald, M, Petrovan, RJ, Donner, A, et al Activation of endothelial cell protease activated receptor 1 by the protein C pathway. Science 2002;296,1880-1882[Abstract/Free Full Text]
- Cheng, T, Liu, D, Griffin, JH, et al Activated protein C blocks p53-mediated apoptosis in ischemic human brain endothelium and is neuroprotective. Nat Med 2003;9,338-342[CrossRef][ISI][Medline]
- Bajzar, L, Morser, J, Nesheim, M TAFI, or plasma procarboxypeptidase B, couples the coagulation and fibrinolytic cascades through the thrombin-thrombomodulin complex. J Biol Chem 1996;271,16603-16608[Abstract/Free Full Text]
- Campbell, W, Okada, N, Okada, H Carboxypeptidase R is an inactivator of complement-derived inflammatory peptides and an inhibitor of fibrinolysis. Immunol Rev 2001;180,162-167[CrossRef][ISI][Medline]
- Campbell, WD, Lazoura, E, Okada, N, et al Inactivation of C3a and C5a octapeptides by carboxypeptidase R and carboxypeptidase N. Microbiol Immunol 2002;46,131-134[ISI][Medline]
- Conway, EM, Van de Wouwer, M, Pollefeyt, S, et al The lectin-like domain of thrombomodulin confers protection from neutrophil-mediated tissue damage by suppressing adhesion molecule expression via nuclear factor B and mitogen-activated protein kinase pathways. J Exp Med 2002;196,565-577[Abstract/Free Full Text]
- Hamada, H, Ishii, H, Sakyo, K, et al The epidermal growth factor-like domain of recombinant human thrombomodulin exhibits mitogenic activity for Swiss 3T3 cells. Blood 1995;86,225-233[Abstract/Free Full Text]
- Suzuki, K, Hayashi, T, Nishioka, J, et al A domain composed of epidermal growth factor-like structures of human thrombomodulin is essential for thrombin binding and for protein C activation. J Biol Chem 1989;264,4872-4876[Abstract/Free Full Text]
- Esmon, CT The roles of protein C and thrombomodulin in the regulation of blood coagulation. J Biol Chem 1989;264,4743-4746[Free Full Text]
- Bourin, MC, Lindahl, U Glycosaminoglycans and the regulation of blood coagulation. Biochem J 1993;289(pt 2),313-330
- Oganesyan, V, Oganesyan, N, Terzyan, S, et al The crystal structure of the endothelial protein C receptor and a bound phospholipid. J Biol Chem 2002;277,24851-24854[Abstract/Free Full Text]
- Fukudome, K, Esmon, CT Identification, cloning, and regulation of a novel endothelial cell protein C/activated protein C receptor. J Biol Chem 1994;269,26486-26491[Abstract/Free Full Text]
- Moody, DB, Ulrichs, T, Muhlecker, W, et al CD1c-mediated T-cell recognition of isoprenoid glycolipids in Mycobacterium tuberculosis infection. Nature 2000;404,884-888[CrossRef][Medline]
- Hong, S, Scherer, DC, Singh, N, et al Lipid antigen presentation in the immune system: lessons learned from CD1d knockout mice. Immunol Rev 1999;169,31-44[CrossRef][ISI][Medline]
- Taylor, FB, Jr, Stearns-Kurosawa, DJ, Kurosawa, S, et al The endothelial cell protein C receptor aids in host defense against Escherichia coli sepsis. Blood 2000;95,1680-1686[Abstract/Free Full Text]
- Xu, J, Qu, D, Esmon, NL, et al Metalloproteolytic release of endothelial cell protein C receptor. J Biol Chem 2000;275,6038-6044[Abstract/Free Full Text]
- Kurosawa, S, Stearns-Kurosawa, DJ, Carson, CW, et al Plasma levels of endothelial cell protein C receptor are elevated in patients with sepsis and systemic lupus erythematosus: lack of correlation with thrombomodulin suggests involvement of different pathological processes. Blood 1998;91,725-727[Free Full Text]
- 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;165,4697-4703[Abstract/Free Full Text]
- Esmon, CT The endothelial cell protein C receptor. Thromb Haemost 2000;83,639-643[ISI][Medline]
- Mann, KG, Kalafatis, M Factor V: a combination of Dr Jekyll and Mr Hyde. Blood 2003;101,20-30[Free Full Text]
- Nicolaes, GA, Dahlback, B Factor V and thrombotic disease: description of a Janus-faced protein. Arterioscler Thromb Vasc Biol 2002;22,530-538[Abstract/Free Full Text]
- Laszik, Z, Mitro, A, Taylor, FB, Jr, et al Human protein C receptor is present primarily on endothelium of large blood vessels: implications for the control of the protein C pathway. Circulation 1997;96,3633-3640[Abstract/Free Full Text]
- Murakami, K, Okajima, K, Uchiba, M, et al Activated protein C prevents LPS-induced pulmonary vascular injury by inhibiting cytokine production. Am J Physiol 1997;272(2 pt 1),L197-L202
- Hancock, WW, Grey, ST, Hau, L, et al Binding of activated protein C to a specific receptor on human mononuclear phagocytes inhibits intracellular calcium signaling and monocyte-dependent proliferative responses. Transplantation 1995;60,1525-1532[ISI][Medline]
- Murphy, C, Livingstone, WJ, White, B Activated protein C inhibits upregulation of both tissue factor and TNF in endotoxin stimulated monocytes. Throm Haemost 2001;(suppl),P509
- Shua, F, Kobayashia, H, Fukudome, K, et al Activated protein C suppresses tissue factor expression on U937 cells in the endothelial protein C receptor-dependent manner. FEBS Lett 2000;477,208-212[CrossRef][ISI][Medline]
- Ishii, H, Salem, HH, Bell, CE, et al Thrombomodulin, an endothelial anticoagulant protein, is absent from the human brain. Blood 1986;67,362-365[Abstract/Free Full Text]
- Esmon, CT Protein C anticoagulant pathway and its role in controlling microvascular thrombosis and inflammation. Crit Care Med 2001;29(7 suppl),S48-S51[CrossRef][ISI][Medline]
- Esmon, CT, Owen, WG Identification of an endothelial cell cofactor for thrombin-catalyzed activation of protein C. Proc Natl Acad Sci U S A 1981;78,2249-2252[Abstract/Free Full Text]
- Dreyfus, M, Magny, JF, Bridey, F, et al Treatment of homozygous protein C deficiency and neonatal purpura fulminans with a purified protein C concentrate. N Engl J Med 1991;325,1565-1568[ISI][Medline]
- Rivard, GE, David, M, Farrell, C, et al Treatment of purpura fulminans in meningococcemia with protein C concentrate. J Pediatr 1995;126,646-652[CrossRef][ISI][Medline]
- Smith, OP, White, B, Vaughan, D, et al Use of protein C concentrate, heparin, and haemodiafiltration in meningococcus-induced purpura fulminans. Lancet 1997;350,1590-1593[CrossRef][ISI][Medline]
- Smith, OP, White, B Infectious purpura fulminans: diagnosis and treatment. Br J Haematol 1999;104,202-207[CrossRef][ISI][Medline]
- Conway, EM, Rosenberg, RD Tumor necrosis factor suppresses transcription of the thrombomodulin gene in endothelial cells. Mol Cell Biol 1988;8,5588-5592[Abstract/Free Full Text]
- Glaser, CB, Morser, J, Clarke, JH, et al Oxidation of a specific methionine in thrombomodulin by activated neutrophil products blocks cofactor activity: a potential rapid mechanism for modulation of coagulation. J Clin Invest 1992;90,2565-2573[ISI][Medline]
- Takano, S, Kimura, S, Ohdama, S, et al Plasma thrombomodulin in health and diseases. Blood 1990;76,2024-2029[Abstract/Free Full Text]
- Faust, SN, Levin, M, Harrison, OB, et al Dysfunction of endothelial protein C activation in severe meningococcal sepsis. N Engl J Med 2001;345,408-416[Abstract/Free Full Text]
- Liaw, PCY, Ferrell, GL, 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;1,662-670[CrossRef][ISI][Medline]
- Gu, JM, Katsuura, Y, Ferrell, GL, et al Endotoxin and thrombin elevate rodent endothelial cell protein C receptor mRNA levels and increase receptor shedding in vivo. Blood 2000;95,1687-1693[Abstract/Free Full Text]
- Slungaard, A, Vercellotti, GM, Tran, T, et al Eosinophil cationic granule proteins impair thrombomodulin function: a potential mechanism for thromboembolism in hypereosinophilic heart disease. J Clin Invest 1993;91,1721-1730[ISI][Medline]
- Slungaard, A, Key, NS Platelet factor 4 stimulates thrombomodulin protein C-activating cofactor activity: a structure-function analysis. J Biol Chem 1994;269,25549-25556[Abstract/Free Full Text]
- Taylor, FB, Jr, Chang, A, Esmon, CT, et al Protein C prevents the coagulopathic and lethal effects of Escherichia coli infusion in the baboon. J Clin Invest 1987;79,918-925[ISI][Medline]
- Bernard, GR, Vincent, JL, Laterre, PF, et al Efficacy and safety of recombinant human activated protein C for severe sepsis. N Engl J Med 2001;344,699-709[Abstract/Free Full Text]
- Solymoss, S, Tucker, MM, Tracy, PB Kinetics of inactivation of membrane-bound factor Va by activated protein C: protein S modulates factor Xa protection. J Biol Chem 1988;263,14884-14890[Abstract/Free Full Text]
- Esmon, CT Modulation of the protein C pathway as a therapy for thrombosis. Sasahara, AA Loscalzo, J eds. Therapeutic agents for thrombosis and thrombolysis. 2001,301-321 Marcel Dekker. New York, NY:
- Okajima, K Regulation of inflammatory responses by natural anticoagulants. Immunol Rev 2001;184,258-274[CrossRef][ISI][Medline]
- Laszik, ZG, Zhou, XJ, Silva, FG Thrombomodulin (TM) but not endothelial cell protein receptor (EPCR) mRNA is downregulated in streptozotocin-induced diabetic rat kidneys [abstract]. Mod Pathol 2003;16,267A
- Kim, AY, Walinsky, PL, Kolodgie, FD, et al Early loss of thrombomodulin expression impairs vein graft thromboresistance: implications for vein graft failure. Circ Res 2002;90,205-212[Abstract/Free Full Text]
- Laszik, ZG, Zhou, XJ, Ferrell, GL, et al Down-regulation of endothelial expression of endothelial cell protein C receptor and thrombomodulin in coronary atherosclerosis. Am J Pathol 2001;159,797-802[Abstract/Free Full Text]
- Ohdama, S, Matsubara, O, Aoki, N Plasma thrombomodulin in Wegener’s granulomatosis as an indicator of vascular injuries. Chest 1994;106,666-671[Abstract/Free Full Text]
- Waugh, JM, Li-Hawkins, J, Yuksel, E, et al Thrombomodulin overexpression to limit neointima formation. Circulation 2000;102,332-337[Abstract/Free Full Text]
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M. E. Papaconstantinou, C. J. Carrell, A. O. Pineda, K. M. Bobofchak, F. S. Mathews, C. S. Flordellis, M. E. Maragoudakis, N. E. Tsopanoglou, and E. Di Cera
Thrombin Functions through Its RGD Sequence in a Non-canonical Conformation
J. Biol. Chem.,
August 19, 2005;
280(33):
29393 - 29396.
[Abstract]
[Full Text]
[PDF]
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B. Dahlback and B. O. Villoutreix
Regulation of Blood Coagulation by the Protein C Anticoagulant Pathway: Novel Insights Into Structure-Function Relationships and Molecular Recognition
Arterioscler. Thromb. Vasc. Biol.,
July 1, 2005;
25(7):
1311 - 1320.
[Abstract]
[Full Text]
[PDF]
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T. van der Poll, M. Levi, J. A. Nick, and E. Abraham
Activated Protein C Inhibits Local Coagulation after Intrapulmonary Delivery of Endotoxin in Humans
Am. J. Respir. Crit. Care Med.,
May 15, 2005;
171(10):
1125 - 1128.
[Abstract]
[Full Text]
[PDF]
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C. Feistritzer and M. Riewald
Endothelial barrier protection by activated protein C through PAR1-dependent sphingosine 1-phosphate receptor-1 crossactivation
Blood,
April 15, 2005;
105(8):
3178 - 3184.
[Abstract]
[Full Text]
[PDF]
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M. J. Ludeman, H. Kataoka, Y. Srinivasan, N. L. Esmon, C. T. Esmon, and S. R. Coughlin
PAR1 Cleavage and Signaling in Response to Activated Protein C and Thrombin
J. Biol. Chem.,
April 1, 2005;
280(13):
13122 - 13128.
[Abstract]
[Full Text]
[PDF]
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H. Xu, L. A. Bush, A. O. Pineda, S. Caccia, and E. Di Cera
Thrombomodulin Changes the Molecular Surface of Interaction and the Rate of Complex Formation between Thrombin and Protein C
J. Biol. Chem.,
March 4, 2005;
280(9):
7956 - 7961.
[Abstract]
[Full Text]
[PDF]
|
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A. Undas, K. E. Brummel-Ziedins, and K. G. Mann
Statins and Blood Coagulation
Arterioscler. Thromb. Vasc. Biol.,
February 1, 2005;
25(2):
287 - 294.
[Abstract]
[Full Text]
[PDF]
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J. Hirsh, M. O'Donnell, and J. I. Weitz
New anticoagulants
Blood,
January 15, 2005;
105(2):
453 - 463.
[Abstract]
[Full Text]
[PDF]
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B. S. Donahue
The Response to Activated Protein C After Cardiopulmonary Bypass: Impact of Factor V Leiden
Anesth. Analg.,
December 1, 2004;
99(6):
1598 - 1603.
[Abstract]
[Full Text]
[PDF]
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Y. M. Fortenberry, H. C. Whinna, H. R. Gentry, T. Myles, L. L. K. Leung, and F. C. Church
Molecular Mapping of the Thrombin-Heparin Cofactor II Complex
J. Biol. Chem.,
October 8, 2004;
279(41):
43237 - 43244.
[Abstract]
[Full Text]
[PDF]
|
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K. Shim, H. Zhu, L. A. Westfield, and J. E. Sadler
A recombinant murine meizothrombin precursor, prothrombin R157A/R268A, inhibits thrombosis in a model of acute carotid artery injury
Blood,
July 15, 2004;
104(2):
415 - 419.
[Abstract]
[Full Text]
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TOP
Abstract
The Activation Complex
