Human endothelial cells and fibroblasts express and produce the coagulation proteins necessary for thrombin generation.

In a previous study, we reported that human endothelial cells (ECs) express and produce their own coagulation factors (F) that can activate cell surface FX without the additions of external proteins or phospholipids. We now describe experiments that detail the expression and production in ECs and fibroblasts of the clotting proteins necessary for formation of active prothrombinase (FV-FX) complexes to produce thrombin on EC and fibroblast surfaces. EC and fibroblast thrombin generation was identified by measuring: thrombin activity; thrombin-antithrombin complexes; and the prothrombin fragment 1.2 (PF1.2), which is produced by the prothrombinase cleavage of prothrombin (FII) to thrombin. In ECs, the prothrombinase complex uses surface-attached FV and γ-carboxyl-glutamate residues of FX and FII to attach to EC surfaces. FV is also on fibroblast surfaces; however, lower fibroblast expression of the gene for γ-glutamyl carboxylase (GGCX) results in production of vitamin K-dependent coagulation proteins (FII and FX) with reduced surface binding. This is evident by the minimal surface binding of PF1.2, following FII activation, of fibroblasts compared to ECs. We conclude that human ECs and fibroblasts both generate thrombin without exogenous addition of coagulation proteins or phospholipids. The two cell types assemble distinct forms of prothrombinase to generate thrombin.

STORE-gastrointestinal functions and gastrointestinal hormones in patients with liver failure.

This study aims to investigate the gastrointestinal functions of patients with liver failure (LF) based on gastrointestinal dysfunction (GD) scores and serum gastrointestinal hormone levels.The GD in LF patients was scored using the gastrointestinal dysfunction scoring criteria. Serum gastrin (GAS), cholecystokinin (CCK), and motilin (MTL) levels were determined in LF patients. In addition, liver function and prothrombin activity were detected, and ultrasonography was performed.The GD score was significantly higher in the LF groups than in the control group. Compared with the control group, serum GAS, CCK, and MTL levels significantly increased in the LF groups, and was positively correlated with the severity of LF. Furthermore, in the LF groups, GD was positively correlated with the severity of LF. However, the GD score and serum GAS, CCK, and MTL levels in the acute LF group were not statistically different, when compared with those in the subacute LF group, acute-on-chronic LF group and chronic LF group.LF plays a key role in the development of GD, and may be the main cause of obvious gastrointestinal symptoms, such as abdominal distension, nausea, vomiting and anorexia, in LF patients. The severity of GD is not associated with LF type, but is positively correlated with the severity of LF, suggesting that GD in LF patients may have complicated mechanisms.

Association of des-γ-carboxy prothrombin production and Sonazoid-enhanced ultrasound findings in hepatocellular carcinomas of different histologic grades.

PURPOSE: We previously reported that hepatocellular carcinoma (HCC) changes to a phenotype producing des-γ-carboxy prothrombin (DCP) during epithelial mesenchymal transition (EMT) in vitro. To confirm this change in vivo, we evaluated the association between DCP production and HCC hemodynamics in patients undergoing resection as EMT and hemodynamic changes are closely associated with each other. METHODS: We evaluated HCC hemodynamics by employing Sonazoid-enhanced ultrasound (SEUS) before surgical resection, and sought associations with histological grade and immunohistochemical staining of DCP in 19 areas from 11 patients. RESULTS: In 10 HCC areas showing early washout (3 min ≥) using SEUS, three areas corresponded to poorly differentiated HCC and the remaining seven areas corresponded to moderately differentiated HCC, and positive DCP staining was observed in only two of the seven moderately differentiated HCC areas, whereas no staining was observed in poorly differentiated HCC areas. Six HCC areas showing intermediate washout (3-10 min) using SEUS were moderately differentiated, of which five demonstrated positive DCP staining (83.3%, 5/6). However, all HCC areas without enhancement in the arterial phase were well-differentiated and did not show DCP staining. CONCLUSION: Our preliminary findings suggest that HCC hemodynamics evaluated by SEUS are associated with histological grade and/or DCP production.

Differential effect of the ultra-low dose and standard estrogen plus dydrogesterone therapy on thrombin generation and fibrinolysis in postmenopausal women.

INTRODUCTION: The objective of this study was to estimate the effects of different doses of oral hormone therapy (HT) on thrombin generation and fibrinolytic activity in postmenopausal women after 12 months of treatment. MATERIAL AND METHODS: Thrombin generation, fibrinolysis activators and inhibitors were determined before and after 12 months of treatment. Participants (180) were assigned (1:1:1) as follows: (1) standard HT group, 17ß-estradiol (1 mg/day) with dydrogesterone (5 mg/day); (2) ultra-low dose HT group, 17ß-estradiol (0.5 mg/day) with dydrogesterone (2.5 mg/day); (3) control group, no treatment. RESULTS: The standard HT led to a higher concentration of prothrombin 1 + 2 fragment (by 5.8%) with lower antithrombin activity (by 6.1%). Compared with baseline, we observed a reduction in mean antithrombin activity in the standard HT group and increases in mean levels of prothrombin 1 + 2 fragment in two HT groups. We found decreases after treatment in both standard and ultra-low dose HT groups in plasminogen activator inhibitor-1 (PAI-1) activity (-32.4% and -19.6%, respectively) and PAI-1 antigen (-9.9% and -7.8%, respectively). Intergroup analysis revealed reduction in both mean PAI-1 activities and PAI-1 antigen levels in the two treatment groups when compared with the control. CONCLUSION: Contrary to the standard estrogen plus dydrogesterone treatment, ultra-low dose HT revealed positive effects on hemostasis by intensifying fibrinolysis through a decrease in both PAI-1 activity and antigen levels, and with no impact on thrombin generation.

Production and characterization of active recombinant human factor II with consistent sialylation.

Coagulation factor II (prothrombin; FII) is the pre-proteolyzed precursor to thrombin in the coagulation cascade. It has 10 sites of gamma-carboxylation, which are required for its bioactivity, and is N-glycosylated at three of four putative sites. Production of recombinant human FII (rhFII) using a platform fed-batch process designed for monoclonal antibody production resulted in low levels of gamma-carboxylation and sialylation. There have not been any prior reports of successful process development and clinical manufacture of rhFII with optimal, consistent gamma-carboxylation and sialylation. In order to develop such a fed-batch process, various process parameters were evaluated to determine their impact on product quality. Process temperature and temperature shift timing were important for both sialic acid level and gamma-carboxyglutamate (Gla) level. In addition, vitamin K concentration and the type of surfactant used for preparation of vitamin K stock solution were also important for gamma carboxylation. A fed-batch study performed with various medium additives known to be involved in the N-glycosylation pathway, such as N-acetyl-d-mannosamine (ManNAc), galactose (Gal), dexamethasone, and manganese sulfate, increased the level of sialylation and enabled the elucidation of some potential bottlenecks in the sialylation pathway. The optimized process based on these studies yielded a reduction in the level of missing Gla by 0.4 moles per mole of rhFII in cell culture and a nearly threefold increase in sialic acid level. The process was successfully implemented at the 2000 L scale where a high Gla level and sialylation levels were achieved in all GMP lots. Biotechnol. Bioeng. 2017;114: 1991-2000. © 2017 Wiley Periodicals, Inc.

Protein induced by vitamin K absence or antagonist II (PIVKA-II) producing large cell neuroendocrine carcinoma (LCNEC) of lung with multiple liver metastases: A case report.

A 78-year-old man was admitted to our hospital for multiple lung and liver tumors. Initial clinical diagnosis was hepatocellular carcinoma (HCC) with lung metastases because of a high value of serum protein induced by vitamin K absence or antagonist II (PIVKA-II) (6,705 mAU/mL). However, a review of a prior CT showed the lung tumor had existed 6 months before liver tumors were detected. The tumors progressed rapidly and the patient died 37 days after admission. Autopsy revealed that both lung and liver tumors exhibited the histology of large cell neuroendocrine carcinoma (LCNEC). Immunohistochemistry revealed that the tumor cells expressed not only neuroendocrine markers but also PIVKA-II diffusely. Hepatoid differentiation was not detected. Background liver did not show any chronic liver disease. The final diagnosis was PIVKA-II producing LCNEC of the lung with multiple liver metastases. PIVKA-II producing tumors other than HCC are extremely rare. To our best knowledge, this is the first case report of PIVKA-II producing neuroendocrine tumors of the lung.

Roles and Signaling Pathways of Des-γ-Carboxyprothrombin in the Progression of Hepatocellular Carcinoma.

Des-γ-carboxyprothrombin (DCP), an abnormal prothrombin produced in human hepatocellular carcinoma (HCC), plays crucial roles in the progression of HCC. DCP binding to cellular mesenchymal-epithelial transition factor (c-Met) is an initial event and consequently stimulates HCC through the increase of c-Met-Janus kinase 1- signal transducers and activators of transcription pathways. DCP stimulates HCC invasion through activation of matrix metalloproteinase via upregulation of extracellular signal-regulated kinase-mitogen-activated protein kinase (MAPK) pathway. DCP stimulates HCC angiogenesis through activation of the DCP-kinase insert domain receptor-phospholipaseC-γ-MAPK pathway. Identification of these pathways is important for designing the therapeutic strategy for HCC.

Phosphatidylserine externalization and procoagulant activation of erythrocytes induced by Pseudomonas aeruginosa virulence factor pyocyanin.

The opportunistic pathogen Pseudomonas aeruginosa causes a wide range of infections in multiple hosts by releasing an arsenal of virulence factors such as pyocyanin. Despite numerous reports on the pleiotropic cellular targets of pyocyanin toxicity in vivo, its impact on erythrocytes remains elusive. Erythrocytes undergo an apoptosis-like cell death called eryptosis which is characterized by cell shrinkage and phosphatidylserine (PS) externalization; this process confers a procoagulant phenotype on erythrocytes as well as fosters their phagocytosis and subsequent clearance from the circulation. Herein, we demonstrate that P. aeruginosa pyocyanin-elicited PS exposure and cell shrinkage in erythrocyte while preserving the membrane integrity. Mechanistically, exposure of erythrocytes to pyocyanin showed increased cytosolic Ca(2+) activity as well as Ca(2+) -dependent proteolytic processing of µ-calpain. Pyocyanin further up-regulated erythrocyte ceramide abundance and triggered the production of reactive oxygen species. Pyocyanin-induced increased PS externalization in erythrocytes translated into enhanced prothrombin activation and fibrin generation in plasma. As judged by carboxyfluorescein succinimidyl-ester labelling, pyocyanin-treated erythrocytes were cleared faster from the murine circulation as compared to untreated erythrocytes. Furthermore, erythrocytes incubated in plasma from patients with P. aeruginosa sepsis showed increased PS exposure as compared to erythrocytes incubated in plasma from healthy donors. In conclusion, the present study discloses the eryptosis-inducing effect of the virulence factor pyocyanin, thereby shedding light on a potentially important mechanism in the systemic complications of P. aeruginosa infection.

Procoagulant and fibrinolytic activity after polytrauma in rat.

The purpose of this study was to determine whether trauma-induced coagulopathy is due to changes in 1) thrombin activity, 2) plasmin activity, and/or 3) factors that stimulate or inhibit thrombin or plasmin. Sprague-Dawley rats were anesthetized with 1-2% isoflurane/100% oxygen, and their left femoral artery and vein were cannulated. Polytrauma included right femur fracture, and damage to the small intestines, the left and medial liver lobes, and right leg skeletal muscle. Rats were then bled 40% of blood volume. Plasma samples were taken before trauma, and at 30, 60, 120, and 240 min. Polytrauma and hemorrhage led to a significant fall in prothrombin levels. However, circulating thrombin activity did not change significantly over time. Antithrombin III and α2 macroglobulin fell significantly by 2 h, then rose by 4 h. Soluble thrombomodulin was significantly elevated over the 4 h. Circulating plasmin activity, plasminogen, and D-dimers were elevated for the entire 4 h. Tissue plasminogen activator (tPA) was elevated at 30 min, then decreased below baseline levels after 1 h. Plasminogen activator inhibitor-1 was significantly elevated at 2-4 h. Neither tissue factor pathway inhibitor nor thrombin activatable fibrinolysis inhibitor changed significantly over time. The levels of prothrombin and plasminogen were 30-100 times higher than their respective active enzymes. Polytrauma and hemorrhage in rats lead to a fibrinolytic coagulopathy, as demonstrated by an elevation in plasmin activity, D-dimers, and tPA. These results are consistent with the observed clinical benefit of tranexamic acid in trauma patients.

High-yield preparation of recombinant human α-thrombin for therapeutic use.

In this study, we established stable cell lines producing 1.5 mg/mL recombinant human prothrombin in 400-L fed-batch culture, using CHO DG44 cells as a host cell line. And we also established a recombinant human α-thrombin purification process that produces a purified product suitable for use as a biopharmaceutical, by using recombinant ecarin from CHO DG44 cells, achieving a total yield of approximately 27% of prothrombin in culture medium. The establishment of stable cell lines with high expression levels, long-term passage stability and satisfactory scale-up are essential to ensure the stable supply of biopharmaceuticals. Furthermore, biopharmaceuticals must be of high quality to assure safety and effectiveness in target applications. We had previously reported that recombinant human prethrombin-2 expression level in a stable cell line established using the mouse myeloma cells, Sp2/0-Ag14, reached 200 µg/mL using animal-free materials in 50-L fed-batch culture. However, the productivity was insufficient to completely replace α-thrombin in human plasma preparations. By employing CHO DG44 cells as a host cell line, we had established a stable cell line and achieved significant improvements in quality, productivity of recombinant human α-thrombin manufacture suitable for use as a biopharmaceutical.

WEDGE: an anticoagulant thrombin mutant produced by autoactivation.

BACKGROUND: The production of therapeutically relevant proteases typically involves activation of a zymogen precursor by external enzymes, which may raise regulatory issues about availability and purity. Recent studies of thrombin precursors have shown how to engineer constructs that spontaneously convert to the mature protease by autoactivation, without the need for external enzymes. OBJECTIVES: Autoactivation is an innovative strategy that promises to simplify the production of proteases of therapeutic relevance, but has not been tested in practical applications. The aim of this study was to provide a direct test of this strategy. METHODS: An autoactivating version of the thrombin mutant W215A/E217A (WE), which is currently in preclinical development as an anticoagulant, was engineered. RESULTS AND CONCLUSIONS: The autoactivating version of WE can be produced in large quantities, like WE made in BHK cells or Escherichia coli, and retains all significant functional properties in vitro and in vivo. The results serve as proof of principle that autoactivation is an innovative and effective strategy for the production of trypsin-like proteases of therapeutic relevance.

Short-term venous stasis induces fibrinolytic activation but not thrombin formation.

AIM: Venous stasis is a well-known risk factor for the development of venous thromboembolism. It is likely that stasis increases the risk of thrombosis by inducing hypercoagulability via the hypoxic procoagulant activation of endothelial and mononuclear cells and the accumulation of activated clotting factors. However, increased rates of thrombin formation have not been demonstrated in response to venous stasis in vivo. METHODS: In this study, we used the venous occlusion (VO) test to determine, if stasis triggers thrombin formation in healthy individuals (n=25) and patients with additional thrombotic risk factors, such as inherited thrombophilia (n=19) and symptomatic atherosclerosis (n=15). Thrombin formation was monitored by measuring plasma levels of free thrombin using a highly sensitive oligonucleotide enzyme capture assay (OECA) in addition to the plasma levels of prothrombin fragment 1+2 (F1+2) and thrombin-antithrombin-complexes (TAT). The plasma levels of activated protein C (APC) were additionally measured using an APC-OECA. RESULTS: VO induced a significant (p<0.05) increase in the levels of tissue-type plasminogen activator and plasmin-α2-antiplasmin-complexes. In all three cohorts, the majority of samples obtained during VO showed no quantifiable thrombin or APC levels. Consistent with these findings F1+2 and TAT did not change. CONCLUSIONS: We conclude that short-term venous stasis induces a profibrinolytic response due to the activation of endothelial cells, but not a prothrombotic response, even in the presence of additional thrombophilic risk factors. Furthermore, our results support the hypothesis that the stasis-induced profibrinolytic activation of endothelial cells occurs independently from thrombin formation.

[A surgically resected case of AFP and PIVKA-II producing gastric cancer with hepatic metastasis].

A 78-year-old man was admitted for workup for a liver tumor. Both serum AFP and PIVKA-II levels were high (2260ng/ml and 806mAU/ml, respectively). Contrast-enhanced CT scan and MRI using Gd-EOB-DTPA demonstrated a liver tumor in segment 6 resembling the imaging patterns of hepatocellular carcinoma (HCC), while the upper gastrointestinal endoscopy revealed a type 2 gastric cancer in the gastric antrum. Although the liver metastasis of the gastric cancer was undeniable, we performed partial resection of segment 6 of the liver and distal gastrectomy under a preoperative diagnosis of double cancer. Histopathologically, gastric tumor consisted of two components, such as well differentiated adenocarcinoma and hepatoid adenocarcinoma. The histology of the liver tumor was similar to that of the hepatoid component in the stomach lesion. Immunohistochemical staining revealed both the gastric and the liver tumors to be positive for AFP and PIVKA-II, yielding a definite diagnosis of AFP and PIVKA-II producing gastric cancer with liver metastasis. Because many cases of this disease have liver metastases at presentation with confusing images with HCC, the diagnosis of liver tumors should be carefully differentiated in the gastric cancer patients with liver tumors, high serum AFP and PIVKA-II levels.

Phenotype-dependent production of des-γ-carboxy prothrombin in hepatocellular carcinoma.

BACKGROUND: Des-γ-carboxy prothrombin (DCP) is an established tumor marker for hepatocellular carcinoma (HCC), but the precise mechanism of its production remains unknown. We have recently demonstrated that cytoskeletal rearrangement during the phenotypic changes involved in epithelial mesenchymal transition (EMT) plays a crucial role in DCP production through the impairment of vitamin K uptake. However, DCP production in long-lasting severe hypoxic conditions with nutrient deprivation-such as transarterial embolization-remains unknown. METHODS: We examined the effects of long-lasting hypoxia with nutrient deprivation, as well as the constitutive expression of hypoxia-inducible factor (HIF)-1α, on EMT status, DCP production, and protein synthesis in human hepatoma cell lines by enzyme-linked immunosorbent assay, immunofluorescent studies, and western blotting. Immunohistochemistry findings for DCP, anti-hepatocyte paraffin 1 (Hep Par 1), and vimentin were examined using human resected HCC samples. RESULTS: Both severe hypoxia with nutrient deprivation and HIF-1α transfection led to the cessation of DCP production, by attenuating protein synthesis through the hypophosphorylation of mammalian target of rapamycin and its effector proteins, indicative of a further phenotypic shift involving impaired liver-specific protein synthesis. In immunohistochemistry, the distribution of DCP- and Hep Par 1-positive HCC cells was mostly similar and vimentin-positive HCC cells were frequently observed in the areas that were negative for Hep Par 1 and/or DCP. CONCLUSIONS: HCC cells produce DCP when they undergo mild phenotypic changes. However, when HCC cells adopt mesenchymal properties they lose their capacity for protein synthesis, and the production of DCP is attenuated. Building upon our previous works, it appears that DCP could be a unique tumor marker that reflects the stepwise phenotypic changes of HCC.

Hypoxia-induced des-gamma-carboxy prothrombin production in hepatocellular carcinoma.

Des-gamma-carboxy prothrombin (DCP) is an established HCC tumor marker, but the precise mechanism of its production is still unclear. Recently, we demonstrated that cytoskeletal changes during epithelial-to-fibroblastoid conversion (EFC) or epithelial mesenchymal transition (EMT) induced by chemicals plays a critical mechanistic role in DCP production via impairment in vitamin K uptake. Our proposed mechanism of DCP production is consistent with substantial clinical evidence. Supplementary vitamin K2 analogues reduced serum DCP levels in hepatocellular carcinoma (HCC) patients. HCC patients with high serum DCP are associated with vascular invasion, metastasis and tumor recurrence. On the other hand, hypoxia has been reported to induce EMT or cytoskeletal changes. Therefore, we examined whether hypoxia induced DCP production during EFC or EMT in HCC cells. Indeed, hypoxic stimulation induced hepatoma cell lines (HepG2 or PLC/PRF/5 cells) to undergo EFC or EMT and these cells produced DCP. Immunofluorescence study demonstrated that hypoxic stimulation impaired labeled low-density lipoprotein uptake, which was a surrogate for vitamin K uptake. In addition, fine filamentous actin network, which has crucial role for clathrin-mediated endocytosis of vitamin K, was disrupted in DCP producing cells by hypoxic stimulation. Thus, hypoxic stimulation induced HCC cells to produce DCP in the same mechanism as chemicals. Furthermore, immunohistochemical study using surgically resected HCC samples showed that a positive staining of nuclear hypoxia inducible factor (HIF)-1alpha was more frequently observed in HCC cells with stronger staining intensity of DCP. Importantly, clinical observations that DCP as an HCC tumor marker was more useful in larger tumors, which is likely to be exposed with hypoxia during tumor development, support our results.

Cytoskeletal changes during epithelial-to-fibroblastoid conversion as a crucial mechanism of des-gamma-carboxy prothrombin production in hepatocellular carcinoma.

Des-gamma-carboxy prothrombin (DCP) is a well-established tumor marker for hepatocellular carcinoma (HCC), but the precise mechanism by which HCC cells produce DCP remains unknown. Our preliminary experiments demonstrated that HepG2 cells with chemical induction of epithelial-to-fibroblastoid conversion (EFC) produced DCP through impairment of vitamin K uptake via cytoskeletal rearrangement. Therefore, in this study we further examined this mechanism in vitro and using human HCC samples. Hepatoma cell lines (HepG2 and PLC/PRF/5) were induced EFC or epithelial-mesenchymal transition (EMT) by phorbol 12-myristate 13 acetate (TPA) or transforming growth factor (TGF)-beta1. We analyzed these cells by ELISA, Western blotting and immunofluorescent studies. We also examined DCP production and E-cadherin expression in human surgically resected HCC samples by immunohistochemical studies. Labeled low-density lipoprotein (LDL) uptake (as a surrogate for vitamin K) was significantly impaired in DCP-producing hepatoma cells following induction of EFC or EMT. Further, filamentous actin, which plays a critical role in clathrin-mediated endocytosis, was dissociated in DCP-producing cells. Latrunculin A, an actin depolymerizer, induced naïve hepatoma cells to produce DCP with impairment of labeled-LDL uptake. In addition, an E-cadherin neutralizing antibody did not induce DCP production. Finally, immunohistochemical studies demonstrated that DCP production was inversely correlated with the intensity of E-cadherin expression in human HCC cells. In conclusion, cytoskeletal changes during EFC or EMT plays a critical mechanistic role in DCP production via impairments in vitamin K uptake.

Application quantum and physico chemical molecular descriptors utilizing principal components to study mode of anticoagulant activity of pyridyl chromen-2-one derivatives.

Factors II, V, VII and Xa have materialized as a key enzymes for the intervention of blood coagulation cascade and for the development of new anti thrombotic agents. The combined density functional quantum mechanical/molecular mechanical (QM/MM) approach has been used to access inhibition of prothrombin and thrombin production. The biological activities of coumarin derivatives as clotting factor inhibitors was quantitatively analyzed in terms of physicochemical parameters utilizing the principal component analysis. Structural requirements for maximal potency were derived from the results of a quantitative structure activity relationship analysis.

Effects of nadroparin, enoxaparin, and unfractionated heparin on endogenous factor Xa and IIa formation and on thrombelastometry profiles.

Measurements of anti-FXa or anti-FIIa (thrombin) activities are conventional tests for biological monitoring of low molecular weight heparin (LMWH) or unfractionated heparin treatment. It was the aim of our study to assess the anticoagulant efficacy of the LMWHs nadroparin and enoxaparin and that of unfractionated heparin not by the above-mentioned isolated measurements but in the physiological environment of clotting plasma or whole blood. The effects of increasing amounts of nadroparin, enoxaparin, or unfractionated heparin on the time-course of FXa or FIIa formation were investigated in tissue factor activated platelet-poor plasma using a subsampling technique and chromogenic substrates. Moreover, the anticoagulant efficacy of these drugs was also investigated in whole blood triggered by the physiological relevant activator collagen/endogenous thrombin using thrombelastometry. Nadroparin is as efficient as enoxaparin concerning suppression of endogenous FXa or FIIa formation. The two LMWHs are capable of suppressing the formation of FIIa as efficient as that of FXa. Compared with equivalent anti-FXa activity, unfractionated heparin is markedly more efficient in suppressing the formation of FXa and FIIa than the LMWHs. Corresponding results were obtained in whole blood. The anticoagulant efficacy of nadroparin was comparable with that of enoxaparin and the influence of unfractionated heparin on thrombelastometry parameters was markedly stronger than that of the two LMWHs. We conclude that LMWHs are efficient inhibitors not only of endogenous FXa formation but also of endogenous FIIa formation. Under our experimental conditions, the anticoagulant efficacy of nadroparin was comparable with that of enoxaparin but markedly lower than that of unfractionated heparin.

Haplotypes of the EPCR gene, prothrombin levels, and the risk of venous thrombosis in carriers of the prothrombin G20210A mutation.

BACKGROUND: Haplotypes A1 and A3 in the endothelial protein C receptor (EPCR) gene are tagged by 4678G/C and 4600A/G respectively. We assessed whether these haplotypes modify the risk of venous thromboembolism in carriers of the prothrombin 20210A allele. DESIGN AND METHODS: We genotyped 4678G/C and 4600A/G in 246 20210A carriers: 84 venous thromboembolism propositi and 162 relatives (13 symptomatic), and in 140 relatives not carrying the 20210A variant. Prothrombin and soluble EPCR (sEPCR) levels were also measured. RESULTS: Among propositi, the mean age at first onset was lower in carriers (35 +/- 8 years) than non-carriers of the 4600G allele (44 +/- 14 years) (p = 0.004). The probability of being free of thrombosis at age 40 was lower in 20210A carriers with the EPCR 4600G allele (p = 0.015). The frequency of the 4600G allele (p=0.002) and the levels of prothrombin antigen (p = 0.002) and sEPCR (p < 0.001) were higher in the propositi than in their asymptomatic relatives. Multivariate analyses showed that the presence of the 4600G allele (OR = 2.5, 95% confidence interval 1.3-5.0), sEPCR > 147 ng/mL (2.8, 1.5-5.2) and prothrombin > 129% (3.8, 1.8-8.3) all increased the thrombotic risk. In bivariate analysis, including the 4600G allele and sEPCR > 147 ng/mL, only the latter remained associated with risk. CONCLUSIONS: These results show that in 20210A carriers the venous thromboembolism risk is influenced both by the actual prothrombin levels and by the EPCR A3 haplotype, via its effect on sEPCR levels.