Plasma sEPCR Levels Research Articles

Could Soluble Endothelial Protein C Receptor Levels Recognize SARS-CoV2-Positive Patients Requiring Hospitalization?

ABSTRACTIntroduction:The endothelial protein C receptor (EPCR) is a protein that regulates the protein C anticoagulant and anti-inflammatory pathways. A soluble form of EPCR (sEPCR) circulates in plasma and inhibits activated protein C (APC) activities. The clinical impact of sEPCR and its involvement in COVID-19 has not been explored. In this study, we investigated whether sEPCR levels were related to COVID-19 patients’ requirement for hospitalization.Methods:Plasma sEPCR levels were measured on hospital admission in 84 COVID-19 patients, and in 11 non-hospitalized SARS-CoV2-positive patients approximately 6 days after reported manifestation of their symptoms. Multiple logistic regression analysis was performed to identify potential risk factors for hospitalization and receiver operating characteristic (ROC) curves were generated to assess their value.Results:In our cohort, hospitalized patients had considerably higher sEPCR levels upon admission compared with outpatients [107.5 (76.7–156.3) vs. 44.6 (12.1–84.4) ng/mL; P < 0.0001)]. The ROC curve using hospitalization as the classification variable and sEPCR levels as the prognostic variable generated an area under the curve at 0.845 (95% CI = 0.710–0.981, P < 0.001). Additionally, we investigated the predictive value of sEPCR combined with BMI, age, or D-dimers.Conclusions:In our cohort, sEPCR levels in COVID-19 patients upon hospital admission appear considerably elevated compared with outpatients; this could lead to impaired APC activities and might contribute to the pro-coagulant phenotype reported in such patients. sEPCR measurement might be useful as a point-of-care test in SARS-CoV2-positive patients.

The H3 Haplotype of the EPCR Gene Determines High sEPCR Levels in Critically Ill Septic Patients.

IntroductionA soluble (s) form of the endothelial protein C receptor (EPCR) circulates in plasma and inhibits activated protein C (APC) activities. The clinical impact of sEPCR and its involvement in the septic process is under investigation. This study determined the frequencies of EPCR haplotypes H1 and H3 to investigate possible associations with plasma admission levels of sEPCR in an intensive care unit (ICU) cohort of septic patients.MethodsThree polymorphisms in the EPCR gene were genotyped in 239 Caucasian critically ill patients, and their plasma sEPCR levels were also measured at the time of admission to the ICU. Multivariate logistic regression analysis controlling for sepsis severity, age, acute physiology and chronic health evaluation (APACHE II) and sequential organ failure assessment (SOFA) scores, lactate level, sex, diagnostic category, length of ICU stay and hospital mortality was performed to determine the effect of EPCR haplotypes H1 and H3 on the levels of sEPCR.ResultsIndividuals carrying at least one H3 allele had significantly higher levels of sEPCR than individuals with no H3 alleles (p < 0.001). No differences were found in the distribution of the H3 allele in the patient groups categorized using the pre-existing and current sepsis-3 definitions.ConclusionUsing the preceding and current sepsis definitions, sEPCR levels and the H3 haplotype were not associated with sepsis severity and the risk of poor outcomes in septic patients; however, the EPCR H3 allele contributed to higher levels of sEPCR.

Endothelial protein C receptor polymorphisms and risk of sepsis in a Chinese population.

ObjectiveTo examine the potential relationship of EPCR polymorphisms and the risk of sepsis in a Chinese population.MethodsSnapshot SNP genotyping assays and DNA sequencing methods were used to detect polymorphisms of the EPCR gene, rs2069948C/T (2532C/T) and rs867186A/G (6936A/G), in 64 patients with sepsis and in 113 controls. Soluble EPCR (sEPCR) was measured by ELISA.ResultsThere were significant differences in the allele and genotype frequencies of EPCR gene rs2069948C/T and allele frequencies of rs867186A/G between male and female patients and controls. Females carrying rs2069948 C/T genotype or T allele and males carrying rs867186 A allele were associated with a significantly increased risk of sepsis. Plasma sEPCR levels of sepsis patients were higher than controls and showed no correlation with EPCR gene polymorphisms.ConclusionsEPCR polymorphisms may be associated with increased risk of sepsis, but this has no effect on the release of sEPCR in patients with sepsis.

Relation between the Level of Soluble Endothelial Protein C Receptor and the Risk of Deep Venous Thrombosis in Sudanese

Background: Deep vein thrombosis (DVT) may lead to serious complication; the pulmonary embolism; one of the most serious conditions that cause morbidity and mortality worldwide. sEPCR circulates in the plasma and has high affinity to bind protein C and activated protein C (APC). This binding interferes with the anticoagulant function of APC and results in increased risk for DVT. The aim of this study is to explore the role of sEPCR as a risk factor for DVT in Sudanese individuals. Methods: A total of 100 Sudanese DVT patients and 100 apparently healthy individuals were recruited for this study. EDTA-anticoagulated venous blood samples were collected from all participants. Plasma sEPCR levels were measured by enzyme linked immunosorbent Assay (ELISA). All results were analyzed using SPSS. Results: The plasma level of sEPCR was higher in DVT group than in healthy individuals, while male patients showed higher level when compared to females. Age correlates positively with sEPCR, whilst BMI and ethnicity showed no effect on the level of sEPCR. Individuals in the top quartiles of showed to increased risk of DVT when compared to those in the lower quartile. Conclusion: It can be concluded that elevated sEPCR level increases the risk to develop DVT in Sudanese. The level of the soluble receptor is influenced by the gender of individual more than by his/her ethnicity or body mass index. Results are also indicative of a much higher risk in those with sEPCR level more than 120 ng/ml when compared to those with lower levels.

Functional Analysis of Two Haplotypes of the Human Endothelial Protein C Receptor Gene

To confirm the effect of the endothelial protein receptor gene (PROCR) haplotypes H1 and H3 on venous thromboembolism (VTE), to study their effect on endothelial protein C receptor (EPCR) expression in human umbilical vein endothelial cells, and to investigate the functionality of H1 tagging single-nucleotide polymorphisms in an in vitro model. Protein C (PC), activated PC, and soluble EPCR (sEPCR) levels were measured in 702 patients with VTE and 518 healthy individuals. All subjects were genotyped for PROCR H1 and H3. Human umbilical vein endothelial cells isolated from 111 umbilical cords were used to study the relation between PROCR haplotypes, PROCR mRNA, cellular distribution of EPCR, and rate of PC activation. Finally, the functionality of the intragenic PROCR H1 single-nucleotide polymorphisms was analyzed using a luciferase-based method. We confirmed that individuals carrying H1 have reduced VTE risk, increased plasma activated PC levels, and reduced plasma sEPCR levels and that individuals with the H3H3 genotype have an increased VTE risk and increased plasma sEPCR levels. In cultured human umbilical vein endothelial cells, H1 is associated with increased membrane-bound EPCR, increased rate of PC activation, and reduced sEPCR in conditioned medium, but does not significantly influence PROCR mRNA levels. In contrast, H3 is associated with reduced membrane-bound EPCR and increased sEPCR in human umbilical vein endothelial cell-conditioned medium, higher levels of a truncated mRNA isoform, and a lower rate of PC activation. Finally, we identified the g.2132T>C single-nucleotide polymorphism in intron 1 as an intragenic H1-specific functional single-nucleotide polymorphism. These results support a protective role of PROCR H1 against VTE and an increased risk of VTE associated with the H3 haplotype.

Renal and Urinary Levels of Endothelial Protein C Receptor Correlate with Acute Renal Allograft Rejection

The Endothelial Protein C Receptor (EPCR) is expressed on leukocytes, on endothelium of large blood vessels and to a lesser extent on capillaries. Membrane bound EPCR plays an important role in the activation of protein C which has anticoagulant, anti-inflammatory and cytoprotective effects. After cleavage by a protease EPCR is also found as a soluble protein. Acute rejection of kidney allografts can be divided in T-cell-mediated rejection (TCMR) and antibody-mediated (ABMR) rejection. The latter is characterized by strong activation of coagulation. Currently no reliable non-invasive biomarkers are available to monitor rejection.Renal biopsies were available from 81 renal transplant patients (33 without rejection, 26 TCMR and 22 ABMR), we had access to mRNA material, matched plasma and urine samples for a portion of this cohort. Renal EPCR expression was assessed by RT-PCR and immunostaining. Plasma and urine sEPCR levels were measured by ELISA.ABMR patients showed higher levels of EPCR mRNA than TCMR patients. EPCR expression on glomeruli was significantly elevated in ABMR patients than in TCMR or control patients. In the peritubular capillaries EPCR expression was higher in ABMR patients than in control patients. EPCR expression was higher in tubules and arteries of rejection patients than in control patients. Plasma sEPCR levels did not differ. Urine sEPCR levels were more elevated in the ABMR group than in patients with TCMR or without rejection. ROC analysis demonstrated that urinary sEPCR is appropriate to discriminate between ABMR patients and TCMR or control patients. We conclude that urinary sEPCR could be a novel non-invasive biomarker of antibody mediated rejection in renal transplantation.

Association of soluble endothelial protein C receptor plasma levels and PROCR rs867186 with cardiovascular risk factors and cardiovascular events in coronary artery disease patients: The Athero Gene Study

BackgroundBlood coagulation is an essential determinant of coronary artery disease (CAD). Soluble Endothelial Protein C Receptor (sEPCR) may be a biomarker of a hypercoagulable state. We prospectively investigated the relationship between plasma sEPCR levels and the risk of cardiovascular events (CVE).MethodsWe measured baseline sEPCR levels in 1673 individuals with CAD (521 with acute coronary syndrome [ACS] and 1152 with stable angina pectoris [SAP]) from the AtheroGene cohort. During a median follow up of 3.7 years, 136 individuals had a CVE. In addition, 891 of these CAD patients were genotyped for the PROCR rs867186 (Ser219Gly) variant.ResultsAt baseline, sEPCR levels were similar in individuals with ACS and SAP (median: 111 vs. 115 ng/mL respectively; p=0.20). Increased sEPCR levels were found to be associated with several cardiovascular risk factors including gender (p=0.006), soluble Tissue Factor levels (p=0.0001), diabetes (p=0.0005), and factors reflecting impaired renal function such as creatinine and cystatin C (p<0.0001). sEPCR levels were not significantly associated with the risk of CVE (median: 110 and 114 ng/mL in individuals with and without future CVE respectively; p=0.68). The rs867186 variant was found to explain 59% of sEPCR levels variability (p<10-200) but did not associate with CVE risk.ConclusionOur findings show that in patients with CAD, circulating sEPCR levels are related to classical cardiovascular risk factors and renal impairment but are not related to long-term incidence of CVE.

Soluble endothelial protein C receptor (sEPCR) is likely a biomarker of cancer‐associated hypercoagulability in human hematologic malignancies

Elevated plasma level of soluble endothelial protein C receptor (sEPCR) may be an indicator of thrombotic risk. The present study aims to correlate leukemia-associated hypercoagulability to high level plasma sEPCR and proposes its measurement in routine clinical practice. EPCR expressions in leukemic cell lines were determined by flow cytometry, immunocytochemistry, and reverse transcription polymerase chain reaction (RT-PCR). EPCR gene sequence of a candidate cell line HL-60 was also determined. Plasma samples (n = 76) and bone marrow aspirates (n = 72) from 148 patients with hematologic malignancies and 101 healthy volunteers were analyzed by enzyme-linked immunosorbent assay (ELISA) via a retrospective study for sEPCR and D-dimer. All leukemic cell lines were found to express EPCR. Also, HL-60 EPCR gene sequence showed extensive similarities with the endothelial reference gene. All single nucleotide polymorphisms (SNPs) originally described and some new SNPs were revealed in the promoter and intronic regions. Among these patients 67% had plasma sEPCR level higher than the controls (100 ± 28 ng/mL), wherein 16.3% patients had experienced a previous thrombotic event. These patients were divided into: group-1 (n = 45) with amount of plasmatic sEPCR below 100 ng/mL, group-2 (n = 45) where the concentration of sEPCR was between 100 and 200, and group-3 (n = 20) higher than 200 ng/mL. The numbers of thrombotic incidence recorded in each group were four, six, and eight, respectively. These results reveal that EPCR is expressed not only by a wide range of human malignant hematological cells but also the detection of plasma sEPCR levels provides a powerful insight into thrombotic risk assessment in cancer patients, especially when it surpasses 200 ng/mL.

Endothelial cell protein C receptor gene 6936A/G polymorphism is associated with venous thromboembolism

Venous thromboembolism (VTE) is a common, yet complex disorder. Genetic factors have been suggested to play a role in disease development. We, therefore, conducted a case-control study to examine the potential association of the 6936A/G polymorphism in the endothelial cell protein C receptor (EPCR) gene with the occurrence of venous thromboembolism. We measured the plasma levels of soluble EPCR (sEPCR) in blood samples collected from 112 patients with VTE and 112 age- and gender-matched healthy donors using enzyme-linked immunosorbent assay (ELISA) and amplified the EPCR gene product by PCR. Gene product bands were sequenced to identify EPCR gene polymorphisms. We found that the 6936 AG and GG genotypes were over-represented in the VTE patients. By multivariate analysis, subjects carrying the 6936 G allele were found to have an increased risk of thrombosis (OR=1.784; 95% CI, 1.113-2.891; P<0.05). In conclusion, the EPCR gene 6936A/G polymorphism, which is associated with elevated plasma sEPCR levels, is a potential candidate risk factor for venous thromboembolism.

Elevated soluble endothelial cell protein C receptor (sEPCR) levels in women with preeclampsia: A marker of endothelial activation/damage?

The endothelial protein C receptor (EPCR) plays a crucial role in the anticoagulant and anti-inflammatory effects of the protein C pathway, whereas its soluble form (sEPCR) exhibits opposite properties. High plasma levels of sEPCR have been observed in subjects carrying the A3 haplotype of PROCR, the EPCR gene. Elevated plasma levels of sEPCR were also recently reported in women with preeclampsia (PE), a multisystemic syndrome involving inflammation, endothelial dysfunction and thrombosis. To determine whether this increase is genetically mediated or acquired, we analyzed sEPCR levels and the A3 haplotype distribution in 145 preeclamptic women and 145 age- and term-matched women with normal pregnancies enrolled in a case-control study. Plasma sEPCR levels were higher in the women with PE than in the controls, and this difference was not due to A3 haplotype over-representation. We observed a positive correlation between sEPCR levels and two markers of endothelium activation/damage (von Willebrand factor and soluble thrombomodulin), and a trend towards a third (sVCAM1). We also found an association between sEPCR levels in the highest quartile and the PE risk. The modest increase of sEPCR levels, together with the correlation with other endothelium activation/damage markers, suggest that it is more an innocent bystander of the endothelium activation/damage than an actor in PE.

The Effects of Endothelial Protein C Receptor Gene Polymorphisms on the Plasma sEPCR Level in Venous Thrombosis Patients.

Objective: The aim of this study was to investigate variations in the endothelial cell protein C receptor gene (EPCRgene) that may play a role in thrombosis and the effects of these variations on the plasma soluble endothelial cell proteinC receptor (sEPCR) level in Turkish patients with venous thrombosis.Material and Methods: This study included 111 thrombosis patients and 73 healthy controls. Following DNAextraction, PCR, SSCP, and DNA sequencing analysis of 4 exons of the EPCR gene was performed. Plasma sEPCR wasmeasured via enzyme-linked immunosorbent assay (ELISA).Results: In all, 3 polymorphisms were detected in exons 1-4. C3998T (SNP no: rs2069952) polymorphism was detectedin intron 2 and C4678G (A1 haplotype) (SNP no: rs9574) in the 3’ untranslated region (3’UTR). There weren’t anysignificant differences in C3998T polymorphism between the control and patient groups. There wasn’t a significantdifference in plasma sEPCR levels between both controls and patients that carried the A1 allele. A4600G substitution (A3haplotype) (SNP no: rs867186) was observed in exon 4 and was associated with a 2.04-fold higher risk of thrombosis.A3 allele carriers had higher sEPCR levels than those without the allele. Mean sEPCR level in the patients with thehomozygous A3 allele was 289 ng μL–1, versus 113.42 ng μL–1 in those with the homozygous A1 allele.Conclusion: The A1 haplotype might offer protection against thrombosis and the A3 haplotype might be associatedboth with elevated plasma sEPCR and elevated risk of venous thrombosis in the Turkish population. Plasma sEPCRlevels were significantly higher in those that carried the A3 allele (4600A>G) (both patients and controls). Among theparticipants that carried the A1 allele (4678C>G), plasma sEPCR did not differ significantly.

Early rise in circulating endothelial protein C receptor correlates with poor outcome in severe sepsis

The endothelial protein C receptor (EPCR) negatively regulates the coagulopathy and inflammatory response in sepsis. Mechanisms controlling the expression of cell-bound and circulating soluble EPCR (sEPCR) are still unclear. Moreover, the clinical impact of EPCR shedding and its potential value to predict sepsis progression and outcome remain to be established. We investigated the time course of plasma sEPCR over the 5 first days (D) of severe sepsis in 40 patients. No significant difference was observed when comparing sEPCR at admission (D1) to healthy volunteers and to patients with vasculitis. We report that the kinetics profile of plasma sEPCR in patients was almost stable at the onset of sepsis with no change from D1 to D4 and then a significant decrease at D5. This pattern of release was consistently observed whatever the level of sEPCR at D1. Characteristics of patients or of infections (except Gram negative) had no or little critical influence on the sEPCR profile. However, we found that sEPCR kinetics was clearly associated with patient's outcome (D28 survival). We demonstrate that a significant but moderate (<15% of basal level) and transient increase in sEPCR level at D2 is associated with poor outcome at D28. Severe sepsis, at the onset, only triggers moderate quantitative changes in plasma sEPCR levels. Our findings suggest that in severe sepsis, an early (at D2), transient but significant increase in circulating sEPCR may be detrimental suggesting that sEPCR could provide an early biological marker of sepsis outcome.

The relation between soluble endothelial protein C receptor and factor VIII levels and FVIII/sEPCR index in healthy infants.

Both soluble endothelial protein C receptor (sEPCR) and factor VIII (FVIII) seem to be potential mediators in thrombotic and inflammatory states. The aim of the present study was to determine the relation between plasma sEPCR and FVIII levels in a group of healthy Turkish infants. The study population consisted of 50 healthy infants aged 6 months (Group 1, n=23) and 12 months (Group 2, n=27) having no acute or chronic infection and/or disease. sEPCR levels and FVIII levels were measured by ELISA and one stage factor assay method, respectively. The sEPCR levels of the infants aged 6 months were found higher than those of the infants aged 12 months (p<0.001). There was a correlation between sEPCR and FVIII levels of the infants in Group 1 (6-month-old infants) (r=0.678, p<0.001). FVIII/sEPCR index was 0.73±0.3 and 1.0±0.5 in Group 1 and Group 2, respectively (p=0.027). A correlation between infant age and FVIII/sEPCR index was found (r=0.312, p=0.027). The FVIII/sEPCR index in healthy infants reflects the physiological condition of this population. The finding showing a positive relationship between sEPCR and FVIII levels suggests a possible interaction between these mediators in healthy infants aged six months.

Soluble endothelial cell protein C receptor and thrombomodulin levels after renal transplantation

Both thrombomodulin (TM) and endothelial protein C receptor (EPCR) are candidate biomarkers of endothelial damage and have a role of anti-thrombotic defense mechanism in vascular structure. In this study, we aimed to investigate soluble EPCR (sEPCR), soluble TM (sTM) and tumor necrosis factor-alpha (TNF-alpha) levels in hemodialysis (HD) and renal transplant (RTx) recipients. Twenty-seven RTx recipients and 15 HD patients were recruited to the study. RTx recipients were evaluated before and 3 months after transplantation. Plasma sEPCR, sTM and TNF-alpha levels were measured at baseline and 3 months later in both groups. Moreover, 27 healthy subjects were evaluated regarding sEPCR. At baseline, there was no difference in sTM, sEPCR, TNF-alpha and C-reactive protein (CRP) between the groups. In paired analysis, sEPCR (266 ± 132 to 117 ± 72 ng/ml), sTM (635 ± 165 to 100 ± 41 ng/ml) and TNF-alpha (11.2 ± 4.3 to 6.0 ± 3.5 pg/ml) were significantly decreased in RTx patients (P < 0.0001) at 3 months, while there was no change in the HD group. In the healthy subjects, sEPCR was found to be 79 ± 26 ng/ml at baseline, which was lower than in both groups. We showed that the recently proposed endothelial damage biomarkers, sTM and sEPCR, are elevated in HD patients and significantly decrease after kidney transplantation.

Soluble endothelial protein C receptor levels in healthy population

Increased levels of sEPCR lead to dysfunction of EPCR-mediated coagulation. The aim of this present study was to determine plasma sEPCR levels in a group of Turkish healthy population including both adults and children. The study population consisted of 230 healthy individuals (108 children and 122 adults) having no acute or chronic disease. Plasma sEPCR levels were measured with ELISA. Analysis revealed a bimodal distribution in both groups. There was a negative relationship between sEPCR levels and the age of individuals (r = -0.385, P = 0.0001). The sEPCR levels of children were found significantly higher than that of adults (P < 0.001). This study is the first study to determine the relationship of sEPCR levels and terms of age. Higher levels of sEPCR may suggest a regulation mechanism for the protein C anticoagulation system over the first years of life. Further studies should be conducted to evaluate the physiological importance and molecular mechanism of increased sEPCR levels in children.

Soluble Endothelial Protein C Receptor: Influence on Arteriovenous Fistula Thrombosis Development in Hemodialysis Patients

Background/Aims: Arteriovenous fistulae (AVF) thrombosis is a common cause of morbidity in hemodialysis (HD) patients. Increased soluble endothelial protein C receptor (sEPCR) levels have been associated with increased risk of venous thrombosis. We aimed to investigate the possible effects of sEPCR levels on the development of AVF thrombosis in adult HD patients. Methods: 60 HD patients and 22 healthy controls were included. Patients were followed for 18 months and were divided into two groups according to AVF thrombosis development: group 1 (with thrombosis) and group 2 (without thrombosis). Also, patients classified into tertiles according to plasma sEPCR levels: lowest, intermediate, and highest. Groups were analyzed for any relationship between sEPCR levels and development of AVF thrombosis. Results: Mean plasma sEPCR levels were significantly higher in HD patients than they were in controls. Group 1 patients had significantly higher sEPCR levels compared with group 2 patients. Patients’ groups were similar regarding other possible risk factors for AVF thromboses. The rate of AVF thrombosis development was significantly higher in the highest sEPCR tertile. Conclusion: This is the first study to analyze sEPCR levels in HD patients. Our findings demonstrate a relationship between plasma sEPCR levels and development of AVF thromboses.

EPCR gene A3 haplotype and elevated soluble endothelial protein C receptor (sEPCR) levels in Turkish pediatric stroke patients

Introduction High plasma levels of sEPCR lead to dysfunction of the EPCR-mediated coagulation. We have evaluated the role of EPCR A3 haplotype with its representative promoter variant 1651 C–G in a total of twenty-seven pediatric stroke patients and fifty-nine healthy subjects. Materials and methods Genotyping of the A3 haplotype was performed with RFLP analysis. Plasma sEPCR levels were measured with ELISA. The mutant 1651 G allele frequency was observed to be 0.166 in the patient group. Common risk factors such as FV 1691 G–A and PT 20210 G–A mutations were also screened. Results and conclusions None of the patients with sEPCR levels below 100 ng/ml carried the A3 haplotype, while patients with elevated sEPCR levels carried the A3 haplotype either in a heterozygous or homozygous state. Our study confirms that there is a strong association between A3 haplotype and elevated sEPCR levels. We suggest that elevated sEPCR levels might increase the risk of stroke at pediatric age when compared to controls. Studies with large series of patients are warranted to confirm this hypothesis.

Haplotypes of the EPCR gene, plasma sEPCR levels and the risk of deep venous thrombosis

Binding of protein C (PC) to the endothelial cell PC receptor (EPCR) stimulates PC activation by increasing the affinity of PC for the thrombin-thrombomodulin complex. A soluble form of this receptor (sEPCR) circulates in plasma and inhibits both PC activation and APC anticoagulant activity. The aim of this study was to investigate whether variations in the EPCR gene or plasma sEPCR levels are risk factors for deep venous thrombosis (DVT). In a large case-control study, the Leiden Thrombophilia Study (LETS), sEPCR levels were measured by ELISA. All subjects were genotyped for three haplotype-tagging SNPs, enabling us to detect all four common haplotypes of the EPCR gene. The distribution of sEPCR levels in the control population was trimodal and was genetically controlled by haplotype 3 (H3). This haplotype explained 86.5% of the variation in sEPCR levels. Carriers of two H3 alleles had higher sEPCR levels (439 ng mL(-1)) than carriers of one H3 allele (258 ng mL(-1)), which had higher levels than non-H3 carriers (94 ng mL(-1)). Haplotype 4 was associated with a slightly increased risk (OR = 1.4, 95%CI:1.0-2.2). The risk of subjects with sEPCR levels in the top quartile (>/= 137 ng mL(-1)) was increased compared to that of subjects in the first quartile (< 81 ng mL(-1)), but since there was no dose-response effect, it is most likely that low sEPCR levels reduce the risk of DVT. Our data do not suggest a strong association between EPCR haplotypes and thrombosis risk, but low sEPCR levels appear to reduce the risk of DVT.

A haplotype of the EPCR gene is associated with increased plasma levels of sEPCR and is a candidate risk factor for thrombosis

AbstractThe endothelial cell protein C (PC) receptor (EPCR) facilitates PC activation by the thrombin-thrombomodulin complex. A soluble form of this receptor (sEPCR) found in plasma inhibits both activated PC (aPC) activity and PC activation by competing for PC with membrane-associated EPCR. Elevated sEPCR levels are found in approximately 20% of healthy subjects, but the mechanisms underlying this interindividual variability are unknown. We measured sEPCR levels in 100 healthy male volunteers, and observed 2 phenotypic groups of subjects. The temporal stability of sEPCR levels suggested genetic control. Extensive analysis of the EPCR gene in these subjects revealed 13 polymorphisms in complete linkage disequilibrium; these defined 3 haplotypes, 1 of which (A3) was strongly associated with high sEPCR levels. The high constitutive sEPCR levels observed in A3 haplotype carriers might reduce the efficiency of the PC system and predispose these subjects to venous thrombosis. By studying 338 patients with venous thrombosis and 338 age- and sex-matched healthy subjects, we found that the A3 haplotype was overrepresented in the patients. In multivariate analysis, subjects carrying the A3 haplotype had an increased risk of thrombosis (odds ratio [OR] = 1.8; P = .004). Thus, the A3 haplotype, which is associated with elevated plasma sEPCR levels, is a candidate risk factor for venous thrombosis.

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

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