Pregnancy loss, tissue factor pathway inhibitor deficiency and resistance to activated protein C

Thrombophilic Mutations and Polymorphisms, Alone or in Combination, and Recurrent Spontaneous Abortion

Generally, recurrent spontaneous abortions (RSAs) have no identifiable cause; yet, vascular alterations during pregnancy may be associated with pregnancy loss. Therefore, we evaluated the association between thrombophilic mutations and RSAs. This case–control study was conducted in 112 patients who had RSAs and 98 health control women. Genomic DNA was extracted from whole blood, and polymorphism genotyping was conducted using polymerase chain reaction. The following 6 genetic variants were analyzed: factor V Leiden, prothrombin mutation, methylenetetrahydrofolate reductase C677T and A1298C, plasminogen activator inhibitor type 1 (4G>5G), and factor XIII G103T (V34L). No correlations were found in any of the investigated polymorphisms. Moreover, 35.0% of cases and 25.5% of controls had at least 2 mutations in combination, and 4.8% of cases and 5.1% of controls had 3, but these combinations were not associated with additional risk. In conclusion, we found no association between the polymorphisms studied and the occurrence of RSAs.

Polymorphisms in antithrombin and in tissue factor pathway inhibitor genes are associated with recurrent pregnancy loss

Recurrent pregnancy loss (RPL) is a multifactorial condition. The effect of antithrombin (SERPINC1), protein C (PROC), thrombomodulin (THBD) and tissue factor pathway inhibitor (TFPI) single nucleotide polymorphisms (SNPs) on the risk of RPL is thus far unknown. Our objective was to determine the association of SNPs in the above mentioned genes with RPL. We included 117 non-pregnant women with three or more consecutive losses prior to 20 weeks of pregnancy without a previous history of carrying a fetus to viability, and 264 healthy fertile non-pregnant women who had at least two term deliveries and no known pregnancy losses. The PROC (rs1799809 and rs1799808), SERPINC1 (rs2227589), THBD (rs1042579) and TFPI (rs10931292, rs8176592 and rs10153820) SNPs were analysed by Real Time PCR. Genotype frequencies for PROC 2418A>G, PROC 2405C>T, THBD 1418C>T, TFPI (T-33C and TFPI C-399T) SNPs were similar in cases and controls. The carriers of SERPINC1 786A allele (GA + AA genotypes) had an increased risk for RPL (odds ratio [OR]: 1.77, 95% confidence interval [CI]: 1.05-3.00, p= 0.034) while women carrying the TFPI -287C allele (TC + CC genotypes) had a protection effect on having RPL (OR: 0.46, 95% CI: 0.26-0.83, p= 0.009). The TCC haplotype for TFPI T-33C/ TFPI T-287C/ TFPI C-399T SNPs was less frequent in cases (5.7%) than in controls (11.6%) (OR: 0.45, 95% CI: 0.23-0.90, p= 0.025). In conclusion, our data indicate that SERPINC1 786G>A variant increases the risk for RPL, while TFPI T-287C variant is protective; however, further studies are required to confirm our findings.

Activation of coagulation in amniotic fluid during normal human pregnancy

INTRODUCTION

Amniotic fluid (AF) is an important medium for fetal development which exhibits high procoagulant activities; however, the role of these procoagulants during pregnancy has not been elucidated and might be associated with pregnancy complications. The current study aimed to evaluate factor X (FX) activation and its association with tissue factor (TF), tissue factor pathway inhibitor (TFPI) and coagulation activation markers in AF during normal human pregnancy.

METHODS

Activation of FX and concentration of TF, free TFPI, D-dimer and prothrombin fragments (F1+2) were evaluated in AF samples obtained for chromosome analysis from 91 women with normal pregnancy: 65 samples were taken from patients at 16-20 weeks of gestation, 9 samples were drawn at 21-30 weeks and 17 samples--after 30 weeks of gestation.

RESULTS

Activation of FX in AF significantly increased during normal pregnancy (from 65±41 to 205±80 equivalent RVV ng/mg total protein, P<0.0001). TF and TFPI levels in AF also rose with gestational age. In contrast, the AF concentration of D-dimer and F1+2, markers of coagulation activation significantly decreased when expressed per mg total protein. Levels of free TFPI correlated with TF (r=0.5, P<0.001), and were 8-fold higher than those of TF during pregnancy.

CONCLUSION

High levels of TFPI might be associated with the inhibition of procoagulant activity in amniotic fluid during normal pregnancy, which may account for the rarity of clinical amniotic fluid embolism.

Genome-wide screening for risk loci of idiopathic recurrent miscarriage in a Han Chinese population: a pilot study

The etiology of recurrent miscarriage (RM) is extremely heterogeneous, including genetic, immunologic, anatomic, endocrinological, and infectious anomalies. About 50% of RM is unexplained or poorly understood, which is called idiopathic recurrent miscarriage (IRM). The primary aim of this study was to identify the genetic loci that might be susceptible to IRM. Forty-four Han Chinese patients with IRM during the first trimester of their pregnancies and 44 healthy sex- and ethnic-matched controls were enrolled in this study. A case-control and genome-wide study was performed and 430 polymorphic microsatellite markers were analyzed. Three loci, 6q27 (D6S446, P = .028), 9q33.1 (D9S1776, P = .037), and Xp22.11 (DXS1226, P = .008), significantly associated with IRM were found. This work identified 3 genetic regions that might harbor genes predisposed to IRM and provided new insights for future genetic and etiological study of IRM. Further study is required to confirm it.

Changes of plasma and placental tissue factor pathway inhibitor-2 in women with preeclampsia and normal pregnancy

OBJECTIVES

To investigate the maternal and fetal plasma changes of tissue factor pathway inibitor-2 (TFPI-2) and its placental expression in women with normal pregnancy and preeclampsia.

MATERIAL AND METHODS

We assessed the plasma TFPI-2 level in non-pregnant, normal pregnant and postpartum women, detected fetal plasma level and expression in placenta, and compared the changes in women with preeclampsia. Time-resolved fluoroimmunoassay and immunohistochemistry were used for plasma and placenta tissue detection, respectively.

RESULTS

Maternal plasma levels of TFPI-2 in normal pregnant women at 13weeks of gestation increased 9.3 times as compared with healthy non-pregnant women (149.3+/-17.1 versus 16.0+/-3.6ng/ml)reached a maximum level ( 282.6+/-17.1ng/ml) at 39weeks of gestation, and dramatically decreased to nearly a non-pregnant level on the first day of postpartum (32.3+/-7.1ng/ml); similar change was found in the placental expression. Fetal plasma TFPI-2 was significantly lower than the maternal level at delivery. The maternal plasma TFPI-2 in preeclampsia was significantly lower compared with that in normal pregnancy, coupled with significantly higher placental expression.

CONCLUSIONS

Placenta may be the main site of the high level of TFPI-2 production in maternal circulation, and the dramatic changes in preeclampsia provide a clue to elucidate its pathogenesis.

A link between a hemostatic disorder and preterm PROM: a role for tissue factor and tissue factor pathway inhibitor

OBJECTIVE

Vaginal bleeding is a risk factor for preterm PROM (PPROM). A disorder of decidual hemostasis has been implicated in the genesis of PROM. Indeed, excessive thrombin generation has been demonstrated in PPROM both before and at the time of diagnosis. Decidua is a potent source of tissue factor (TF), the most powerful natural pro-coagulant. A decidual hemostatic disorder may link vaginal bleeding, PPROM and placental abruption. This study was conducted to determine the behaviour of maternal TF and its natural inhibitor, the tissue factor pathway inhibitor (TFPI) in PPROM.

METHODS

This cross-sectional study included women with PPROM (n = 123) and women with normal pregnancies (n = 86). Plasma concentrations of TF and TFPI were measured by a sensitive immunoassay. Non-parametric statistics were used for analysis.

RESULTS

(1) The median maternal plasma TF concentration was significantly higher in patients with PPROM than in women with normal pregnancies (median: 369.5 pg/mL; range: 3.27-2551 pg/mL vs. median: 291.5 pg/mL; range: 6.3-2662.2 pg/mL respectively, p = 0.001); (2) the median maternal TFPI plasma concentration was significantly lower in patients with PPROM than in women with normal pregnancies (median: 58.7 ng/mL; range: 26.3-116 ng/mL vs. median: 66.1 ng/mL; range: 14.3-86.5 ng/mL respectively, p = 0.019); (3) there was no correlation between the plasma concentration of TF and TFPI and the gestational age at sample collection; and (4) among patients with PPROM there was no association between the presence of intra-amniotic infection or inflammation and median plasma concentrations of TF and TFPI.

CONCLUSIONS

(1) Patients with PPROM have a higher median plasma concentration of TF and a lower median plasma concentration of TFPI than women with normal pregnancies. (2) These findings suggest that PPROM is associated with specific changes in the hemostatic/coagulation system.