Interaction of the protein C/protein S anticoagulant system, the endothelium and pregnancy

Use of anticoagulants to improve pregnancy outcomes in couples positive for M2 haplotype: A systematic review

BACKGROUND

Placental mediated pregnancy complications (PMPC) are common, often recurring, and pose a significant health risk to mother and fetus. Evidence suggests that the hypercoagulable state associated with many PMPC, could reflect reduced expression of Annexin 5 (ANXA5), a naturally occurring anticoagulant protein in placental tissue. The ANXA5 M2 haplotype is a genetic variant, which results in reduced expression of ANXA5 protein. M2 haplotype carrier couples may therefore be at increased risk of PMPC. Evidence regarding the effectiveness of anticoagulation to prevent PMPC is inconsistent. Furthermore, studies have not selected or stratified for M2 haplotype carriers, in whom there is a predisposition to hypercoagulability, to assess the effectiveness of anticoagulation, which may vary from those without the M2 haplotype.

OBJECTIVES AND RATIONALE

The aim of this study was to systematically review the current evidence to assess whether anticoagulant treatment improves pregnancy outcomes in couples positive for M2 haplotype.

SEARCH METHODS

The review was registered on PROSPERO (CRD42022343943). A comprehensive literature search was performed using MEDLINE, Embase and Cochrane collaboration databases from inception to January 2023. Two reviewers assessed the articles for eligibility and extracted the data simultaneously. Primary outcome was successful pregnancy and live birth. Secondary outcomes included PMPC (implantation failure, miscarriage, pre-eclampsia, preterm birth and fetal growth restriction).

OUTCOMES

From a pool of 410 references, 10 were selected for full text review, of which three studies (a post hoc analysis of a randomised controlled trial, cohort study and a case report) were included in this review. Included studies comprised of 223 individuals, 129 of whom who received anticoagulation treatment after testing positive for M2 haplotype. The studies collectively showed an improvement in pregnancy outcomes in M2 haplotype positive individuals however, given the heterogeneity of studies, it was not possible to conduct a meta-analysis and draw firm conclusions.

WIDER IMPLICATIONS

Current evidence is limited, such that the value of screening couples for the M2 haplotype to select or stratify for treatment with prophylactic anticoagulation remains unknown. Thus, further studies including well designed, large, multi-centre randomised controlled trials are required to assess whether anticoagulation treatment will be effective in improving pregnancy outcomes in M2 haplotype couples.

Hemostasis in the Pregnant Woman, the Placenta, the Fetus, and the Newborn Infant

The hemostasis system is composed of procoagulant, anticoagulant, and fibrinolytic proteins that interact with endothelial and blood cells and with each other in a complex system of checks and balances to maintain blood flow while preventing both hemorrhage and thrombosis. Pregnancy is a unique physiological state in which biological alterations predispose both mother and fetus to both bleeding and clotting. The placenta is a vascular interface for maternal and fetal blood exchange which predisposes the mother to hemorrhage. Maternal hemostasis presents a compensatory hypercoagulability including elevated factor VIII, von Willebrand factor, fibrinogen and thrombin generation, decreased thrombin regulation with resistance to activated protein C and decreased free protein S, and decreased fibrinolysis with increased plasminogen activator inhibitors. The placental vascular surface is of fetal trophoblastic origin that derives many characteristics of endothelium but differs in that tissue factor is constitutively expressed. Ontogeny of fetal hemostasis is characteristic. Platelets, von Willebrand factor, factor VIII, and fibrinogen are expressed and mature early in gestation, while vitamin K-dependent and contact factors exhibit delayed development. The fetal hemostatic system has a decreased capacity to generate or regulate thrombin, resulting in a fragile balance with little capacity to compensate under stress conditions, particularly in the infant born prematurely. Dysfunction of the maternal/placental/fetal unit gives rise to gestational disorders including preeclampsia, fetal growth restriction, placental abruption, and premature delivery. Knowledge of normal hemostasis levels and function are critical to evaluate bleeding or clotting syndromes in the pregnant woman and her fetus or newborn infant.

Effects of MTHFR C677T polymorphism on vitamin D, homocysteine and natural killer cell cytotoxicity in women with recurrent pregnancy losses

STUDY QUESTION

Is there any relationship between vitamin D [25 (OH) vitamin D], total plasma homocysteine and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in women with recurrent pregnancy losses (RPL)?

SUMMARY ANSWER

Women with MTHFR 677TT (homozygous mutation, TT) genotype have significantly lower vitamin D levels, higher homocysteine and natural killer (NK) cell cytotoxicities than those of women with MTHFR 677CC (wild type, CC) and 677CT (heterozygous mutation, CT) genotypes.

WHAT IS KNOWN ALREADY

Vitamin D insufficiency, MTHFR C677T polymorphism and hyperhomocysteinemia have been reported as risk factors for RPL. However, the relationship between these risk factors is not known in this population.

STUDY DESIGN, SIZE, DURATION

This is a retrospective cross-sectional study, including 837 women with RPL, who were enrolled in Reproductive Medicine and Immunology, Chicago Medical School, between 2012 and 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women with two or more RPL prior to 20 weeks of gestation were included. To investigate whether the MTHFR C677T polymorphism affects the levels of homocysteine and vitamin D as well as immune parameters in women with RPL, biochemical data, such as plasma total homocysteine and serum vitamin D levels, and immune parameters, including NK cell cytotoxicity, were analyzed by MTHFR C677T genotype (CC, CT and TT).

MAIN RESULTS AND THE ROLE OF CHANCE

The serum level of vitamin D in TT was significantly lower when compared with those of CT (P = 0.001) and CC (P = 0.003), while the level of homocysteine in TT was significantly higher than those in CT (P = 0.01) and CC (P = 0.01). NK cytotoxicity in TT was significantly higher than that of CC (P = 0.04) but not CT (P = 0.09). There was a significant negative correlation between the levels of vitamin D and homocysteine in TT (r = -0.357, P < 0.01). In multivariate analysis, vitamin D insufficiency (<30 ng/ml) was an independent risk factor for hyperhomocysteinemia (adjusted odds ratio 1.89, 95% CI 1.41-2.52).

LIMITATIONS, REASONS FOR CAUTION

The study was retrospective and included only women with RPL but not healthy fertile controls. In addition, folic acid, vitamin B6 and B12 intake, which could modify the level of homocysteine and vitamin D, were not investigated. Thus, a considerable part of women might have folic acid and vitamin D supplementation and prenatal vitamin pills, and there are probable confounders in this study associated with unrestricted vitamin supplementation. Therefore, the findings should be carefully interpreted and applied to RPL women with MTHFR gene polymorphism.

WIDER IMPLICATIONS OF THE FINDINGS

The findings attained in this analysis regarding the MTHFR polymorphism and its relationship with vitamin D, homocysteine and NK cytotoxicity may aid in uncovering the underlying etiology and mechanism for RPL. The study highlights an interplay between nutrition and immune responses in RPL.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was received for this study. None of the authors have any conflict of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Phosphatidylcholine in the groove of endothelial cell protein C receptor (EPCR) regulates EPCR conformation and protein C recognition

Endothelial cell protein C receptor (EPCR), the cellular receptor for protein C (PC), facilitates PC activation through the thrombin/thrombomodulin complex and regulates thrombin generation. Under pathophysiological conditions like sepsis, the interactions between EPCR and PC become impaired. Previous studies have demonstrated that the EPCR contains a phospholipid in the antigen-binding groove that is responsible for the structural stability of the EPCR and for PC recognition. However, an understanding at the atomic level during ligand recognition is not fully developed. Molecular dynamics simulations along with potential of mean force (PMF) calculations were carried out in order to provide molecular insight into the dynamics and free energies of EPCR-PC in the absence/presence of phospholipid, namely lysophosphatidylcholine (lysoPCh) and phosphatidylcholine (PCh) in the antigen-binding groove of the EPCR. Our data reveal that the presence of lipid maintains the optimal conformation of the EPCR for PC binding. PMF data further suggest that the PCh system is the most stable in comparison with the other systems (lysoPCh and no lipid). With regards to the two hydrophobic tails of PCh, one lipid tail regulates EPCR conformation while the other promotes ligand recognition by interacting with the keel residue (Phe-4) of PC. Due to the lack of one hydrophobic tail for the lysoPCh system, the EPCR conformation is retained but the affinity of the EPCR towards the ligand (PC) is reduced. Our studies for the first time explore the possible mode of ligand recognition by the EPCR via the involvement of phosphatidylcholine within its hydrophobic groove. The present work provides insight into PCh-dependent ligand recognition and hence regulation of the protein C/EPCR complex formation.

Relationship between mean platelet volume and recurrent miscarriage: a preliminary study

INTRODUCTION

The aim of the study was to examine the relationship between mean platelet volume (MPV) and recurrent miscarriage in order to illuminate the etiopathogenesis of recurrent miscarriage.

MATERIAL AND METHODS

We retrospectively investigated the data of 120 patients with unexplained recurrent miscarriage (group 1), and compared them with the data of 120 match-paired patients in the control group (group 2). The definition of recurrent miscarriage was accepted as two or more failed clinical pregnancies which were documented by ultrasonography or histopathologic examination. All patients in the recurrent miscarriage group were evaluated with diagnostic tests for the etiology of recurrent miscarriage. Total blood count parameters, including hemoglobin, mean corpuscular volume, red cell distribution width, white blood cells, platelets, and mean platelet volume, were compared.

RESULTS

The average patient age at the time of examination was 29.07 ±2.81 years in group I and 28.53 ±3.5 years in group II (p > 0.05). Mean body mass index (BMI) was similar between group 1 and group 2, 22.54 ±3.17 and 22.99 ±2.38, respectively (p > 0.05). Mean hemoglobin, mean corpuscular volume, red cell distribution width, and white blood cell and platelet levels were similar in both groups (p > 0.05). Mean platelet volume levels were significantly higher in group I (9.45 ±1.09 fl) than in group II (7.63 ±0.52 fl) (p = 0.001).

CONCLUSIONS

Higher MPV values in the study group suggest and support the importance of thromboembolic events in the etiology of recurrent miscarriage.

Thrombin generation, D-dimer and protein S in uncomplicated pregnancy

Gestational age-specific reference values are essential for the accurate interpretation of haemostatic tests during pregnancy.

Our 1-year prospective study included 40 healthy pregnant women with a median age of 30 (range 22–40) years; the subjects were followed in order to establish the gestational age dependent values for endogenous thrombin potential (ETP), D-dimer and protein S (activity and free).

During the first trimester 50% of studied women had ETP >100% (reference values out of pregnancy); in the second trimester an ETP over 100% was observed in all women; ETP values remained unchanged during the third trimester. In the first trimester, the median D-dimer concentration of 0.30 mg/L, in the second 0.91 mg/L and in the third of 1.45 mg/L were observed. During the first trimester 14/40 subjects had protein S activity below reference range (<59%, out of pregnancy); the median value of 61.35; interquartile range (IQR) 20.38; in the second 21/37; the median value of 53.1 (IQR 15.65); in the third trimester 28/37 had low level of protein S activity with the median value of 49.0 (IQR 18.8). Free protein S showed a slight decrease from the first trimester; it remained almost stable during the rest of pregnancy, with the equal number of pregnant women with reduced free protein S.

Related to the gestational age, a significant increase of ETP and D-dimer, from the second trimester was observed; the decrease of protein S was observed already from the early pregnancy, with more pronounced variability of protein S activity.

Low dose aspirin and low-molecular-weight heparin in the treatment of pregnant Libyan women with recurrent miscarriage

Background

Recurrent miscarriage is a major women’s health problem. Aspirin and heparin have been shown to have potentially beneficial effects on trophoblast implantation. However, few published data on this issue are available from developing countries.

Methods

An open clinical trial was conducted at the Department of Obstetrics and Gynecology at Misurata Teaching Hospital in Libya from January 2009 to December 2010 to investigate the effects of treatment with low dose aspirin (LDA) versus treatment with low-molecular-weight-heparin (LMWH) in combination with LDA on patients with a history of recurrent miscarriages. A total of 150 women were enrolled in the study. Women were eligible for the study if they had a history of three or more consecutive miscarriages. Participants were randomly assigned to receive either LDA (75 mg daily) alone or a combination of LDA and LMWH (75 women per treatment group). The primary outcomes were the rate of miscarriages and live births for each group.

Results

Compared with the group who received LDA alone, the combination group had a significantly lower number of miscarriages (22/75 [29%] vs. 43/75 [47%], P < 0.001) and had a significantly higher number of live births (53/75 [71%] vs. 32/75 [42%], P < 0.001). Two preterm infants in the LDA group and three in the combination group were admitted to the neonatal intensive care unit. There were no significant differences in the mean (SD) birth weights of neonates born in either group (2955.4 ± 560 vs. 3050 ± 540 g for the LDA and combination groups, respectively, P = 0.444). There were no congenital abnormalities detected in either group.

Conclusion

The combination of LDA and LMWH is better than LDA alone for the maintenance of pregnancy in patients with recurrent first trimester miscarriage.

Trial registration

NCT01917799

Does Anticoagulant Therapy Improve Pregnancy Outcome Equally, Regardless of Specific Thrombophilia Type?

The study was conducted to evaluate the effect of anticoagulant therapy in women with thrombophilia and to detect the possible differences among carriers of mutations (factor V [FV] Leiden and FIIG20210) and those with natural anticoagulant deficiency. The 4-year prospective investigation included 85 pregnant women, with a history of recurrent fetal loss (RFL). They were treated with prophylactic doses of low-molecular-weight heparin (nadroparin) starting from 6 to 8 weeks of gestation. Pregnancy outcomes were evaluated based on the thrombophilia type. Carriers of thrombophilic mutations had a live birth rate of 93%, compared to 41.6% for women with natural anticoagulant deficiencies. Significant differences between the groups were also observed for intrauterine fetal death, intrauterine growth restriction, and postpartum thrombosis. The optimal therapy for women with natural anticoagulant deficiency and RFL remains unclear and future prospective study with a large number of patients is required to determine the best treatment for these severe thrombophilic conditions.

SPIN (Scottish Pregnancy Intervention) study: a multicenter, randomized controlled trial of low-molecular-weight heparin and low-dose aspirin in women with recurrent miscarriage

To assess whether treatment with enoxaparin and low-dose aspirin, along with intensive pregnancy surveillance, reduces rate of pregnancy loss compared with intensive pregnancy surveillance alone in women with history of 2 or more consecutive previous pregnancy losses, a parallel group, multicenter, randomized controlled trial was performed in the United Kingdom and New Zealand. Participants (n = 294) presenting for initial antenatal care at fewer than 7 weeks' gestation with history of 2 or more consecutive previous pregnancy losses at 24 or fewer weeks' gestation and no evidence of anatomic, endocrine, chromosomal, or immunologic abnormality were randomly assigned to receive either enoxaparin 40 mg subcutaneously and 75 mg of aspirin orally once daily along with intense pregnancy surveillance or intense pregnancy surveillance alone from random assignment until 36 weeks' gestation. The primary outcome measure was pregnancy loss rate. Of the 147 participants receiving pharmacologic intervention, 32 (22%) pregnancy losses occurred, compared with 29 losses (20%) in the 147 subjects receiving intensive surveillance alone, giving an odds ratio of 0.91 (95% confidence interval, 0.52-1.59) of having a successful pregnancy with pharmacologic intervention. Thus, we observed no reduction in pregnancy loss rate with antithrombotic intervention in pregnant women with 2 or more consecutive previous pregnancy losses. The trial was registered at http://www.controlled-trials.com as ISRCTN06774126.

Childhood and teenage stroke

OBJECTIVE

The purpose of this manuscript is to review the various etiologies and to discuss the therapeutic issues in childhood stroke.

METHODS

A PubMed search of literature pertaining to childhood stroke was conducted from 1983 to 2008 using specific key search words pertinent to cerebrovascular disorders in childhood.

RESULTS

The analysis of the multiple causes of childhood stroke including arterial ischemic strokes and cerebral venous thrombosis was presented. Current therapy and outcome data in childhood stroke are also discussed throughout the length of the article.

CONCLUSIONS

With increasing vigilance among physicians and improved neuroimaging modalities, the diagnosis of childhood stroke is now made earlier, with increasing frequency and greater accuracy. However, larger and well-controlled studies regarding the optimal management of childhood stroke in terms of the use of both antithrombotic drugs and anticoagulation are still needed in addition to longitudinal follow-up studies of children with stroke.

Light-chain removal by plasmapheresis in myeloma-associated renal failure

BACKGROUND

Although plasmapheresis has been recommended to reverse nephrotoxic elevations of serum free light chains (sFLCs), there are scant published data on removal of sFLC measured with modern assays.

STUDY DESIGN AND METHODS

sFLC levels were recorded in two patients with myeloma-associated renal failure receiving multiple plasmapheresis procedures.

RESULTS

In one patient, presenting with acute renal failure 8 months after diagnosis of kappa-LC myeloma, 16 plasmapheresis procedures neither reduced sFLC levels (percent removal ranging from -70% to +40%) nor improved renal function. In another patient who presented with leukemic immunoglobulin A-lambda myeloma and acute renal failure, sFLC decreased by 30 to 60 percent after each plasmapheresis procedure, but rebounded within 5 to 10 hours. Renal failure occurred despite plasmapheresis, and hemodialysis was required.

CONCLUSIONS

In both patients, plasmapheresis failed to effectively lower sFLC levels. The results provide initial biologic data supporting the conclusions of a recent randomized multicenter clinical trial in which plasmapheresis was an ineffective adjunct to chemotherapy for myeloma-associated acute renal failure.

Protein C, protein S, and thrombomodulin in amniotic fluid. A preliminary study

OBJECTIVES

The main components of protein C anticoagulant system are protein C (PC), protein S (PS) and thrombomodulin (TM); the system plays a protective role in pregnancy, mainly because it prevents the utero-placental circulation from local thrombosis. It is unknown whether the protein C anticoagulant pathway exists in amniotic fluid. The aim of the present study is to find out whether these three components are present in amniotic fluid.

STUDY DESIGN

The study group consisted of 50 parturients with an uneventful pregnancy and birth and 25 non-pregnant controls. Amniotic fluid and blood were sampled at the end of the 1st stage of labor. PC, PS and TM were measured by immunoenzymatic method.

RESULTS

All the samples of amniotic fluid contained measurable amounts of antigens of PC, PS and TM, although their concentrations were significantly lower than in the mother's blood: (i) The concentration of PC in amniotic fluid was 6.24+/-3.50% and PS 2.40+/-1.64%, while in the mothers' plasma it was 138.26+/-12.38% and 93.15+/-13.24%, respectively (P<0.0001). (ii) TM concentration in amniotic fluid constituted 63.92% of the concentration in the mother's blood (2.71+/-1.21 ng/mL vs. 4.24+/-0.88 ng/mL, P<0.001).

CONCLUSION

Protein C, protein S and thrombomodulin are physiological constituents of the amniotic fluid. As their concentrations are low, it is reasonable to assume that they cannot counterbalance the procoagulant activity of amniotic fluid.

The clinical outcome and toxicity of high-dose chemotherapy and autologous stem cell transplantation in patients with myeloma or amyloid and severe renal impairment: a British society of blood and marrow transplantation study

The outcome of high-dose chemotherapy (HDT) was evaluated retrospectively in 27 patients with myeloma and four patients with AL amyloidosis with severe renal impairment. Twenty-three patients were receiving dialysis and the rest had a creatinine clearance of <20 ml/min. The median melphalan dose was 140 mg/m2 (range: 60-200 mg/m2), but 10 patients (37%) received 200 mg/m2. Myeloid and platelet engraftment were similar to that seen in patients without renal failure. Five of 27 patients died of transplant-related toxicity before the day 100. Twenty of 27 patients had a response (70%). The median time to disease progression was 32 months (range: 6-54 months) and the median time to best response was 6.5 months. Four of 17 evaluable patients (24%) became dialysis-independent at a median of 5 months post-HDT/stem cell transplantation. At a median follow-up of 70 months, 7/23 patients with myeloma were alive but three of these seven patients had progressive disease. Two of the four patients with amyloidosis have survived. HDT is feasible in these patients and results in 5-year survival in about one-third of patients.

Approach to Acute Renal Failure With Multiple Myeloma: Role of Plasmapheresis

Multiple myeloma is commonly complicated by renal failure, which limits therapeutic options and aggravates the prognosis. In myeloma the most common cause of advanced renal failure is myeloma kidney, where light chains produced by tumor cells precipitate and impede kidney function. We suggest that plasma exchange is an appropriate intervention in advanced renal failure from multiple myeloma, and support this notion with two case reports. The two elderly individuals had advanced chronic and acute renal failure, and recovered after the removal of large quantities of light chains by existing membrane separation techniques. We also present an algorithm to approach renal failure and myeloma.

Soluble thrombomodulin levels among women with a history of recurrent pregnancy loss, with or without antiphospholipid antibodies

The endothelial cells produce substances whose elevated plasma levels acquire predictive value for the development of events. For instance, soluble thrombomodulin (sTM) levels evidence endothelial cell injury. Under specific clinical conditions the levels of sTM are raised, such as in patients with certain autoimmune disorders, pre-eclampsia or antiphospholipid syndrome. The levels of sTM, as an endothelial injury marker, were evaluated in 65 women with a history of recurrent pregnancy loss (12 with autoimmune disorders, 19 pregnant women and nine with a history of gestational hypertension or pre-eclampsia or eclampsia); 13 of them had antiphospholipid antibodies. sTM levels could be used as a predictor of pregnancy loss in future prospective studies. We compared those levels with the levels found in control groups without recurrent pregnancy loss (20 healthy women and 14 women with autoimmune disorder). There were no statistically significant differences (P = 0.729) in the levels of sTM between the recurrent pregnancy loss group (31.1 ng/ml) and the healthy control group (31.4 ng/ml) or between the different subgroups with recurrent pregnancy loss (P = 0.873) and the healthy control group or the control group with autoimmune disorder (28.0 ng/ml). There were no statistically significant differences (P = 0.605) in the levels of sTM among the patients with recurrent pregnancy loss, with or without moderate or high antiphospholipid antibodies (32.0 versus 23.3 ng/ml). Consequently, the levels of sTM would not seem to be a useful tool, as an endothelial injury marker, in women with a history of recurrent pregnancy loss with or without antiphospholipid antibodies.

The G-to-T point mutation in codon 34 of the factor XIII gene and the risk of pre-eclampsia

A G-to-T point mutation in exon 2 of the FXIII A-subunit gene results in a leucine rather than valine at amino acid position 34 of the factor XIII molecule. The presence of leucine has been associated with a reduced risk of both arterial and venous thrombosis. We examined the prevalence of this point mutation in 102 cases of pre-eclampsia and 208 matched control subjects, as inherited and acquired risk factors for arterial and venous thrombosis are associated with an increased risk of pre-eclampsia. The GT genotype was observed in 38% of controls and 29.4% of cases and the TT genotype was observed in 6.7% of controls and 5.9% of cases. In subjects heterozygous for the T genotype (GT) the relative risk of pre-eclampsia was 0.7 [95% confidence interval (CI95 ) 0.4-1.1] when compared with the GG genotype. For subjects homozygous for the T allele the relative risk for pre-eclampsia was 0.8 (CI95 0.3-2.1) when compared with the GG genotype. The risk associated with the T allele in the heterozygous and homozygous forms compared with the GG genotype was 0.7 (CI95 0.4-1.1). We conclude that the presence of leucine at this site is not associated with a protection against pre-eclampsia to the magnitude of that reported in other thrombotic disease.

Cost-effectiveness of screening for the factor V Leiden mutation in pregnant women

The factor V Leiden (FVL) mutation is associated with vascular complications in pregnancy, and routine screening of all pregnant women has been suggested. We did a prospective, unselected study in 967 pregnant women to evaluate the cost-effectiveness of screening all women, or only those with a personal or family history of venous thrombosis (n=113). When anticoagulant prophylaxis was assumed to effect a 50% reduction in vascular complications, we recorded an additional management cost of 3768 pounds sterling with selective screening and 39,841 pounds sterling with universal screening. This additional cost would result in prevention of less than one and three vascular events,respectively. Our findings, therefore, suggest that screening of pregnant women for the FVL mutation is not cost-effective.