Understanding recurrent pregnancy loss: recent advances on its etiology, clinical diagnosis, and management

A critical review of the recent concept of regulatory performance of DNA Methylations, and DNA methyltransferase enzymes alongside the induction of immune microenvironment elements in recurrent pregnancy loss

Recurrent pregnancy Loss (RPL)is a frequent and upsetting condition. Besides the prevalent cause of RPL including chromosomal defects in the embryo,the effect of translational elements like alterations of epigenetics are of great importance. The emergence of epigenetics has offered a fresh outlook on the causes and treatment of RPL by focusing on the examination of DNA methylation. RPL may arise as a result of aberrant DNA methylation of imprinted genes, placenta-specific genes, immune-related genes, and sperm DNA, which may have a direct or indirect impact on embryo implantation, growth, and development. Moreover, the distinct immunological tolerogenic milieu established at the interface between the mother and fetus plays a crucial role in sustaining pregnancy. Given this, there has been a great deal of interest in the regulation of DNA methylation and alterations in the cellular components of the maternal-fetal immunological milieu. The research on DNA methylation's role in RPL incidence and the control of the mother-fetal immunological milieu is summed up in this review.

Regulatory role of miR-125a expression with respect to its target genes LIFR, ERBB2 and STAT3 in the pathogenesis of recurrent pregnancy losses

OBJECTIVES

Studies have investigated miR-125a for its predictable role in recurrent pregnancy loss (RPL) cases to regulate many biological events required for the maintenance of pregnancy by regulating its confirmed target genes LIFR, ERBB2 and STAT3.

METHODS

The present study included 40 cases of women with at least two RPLs in ≤20 weeks of gestation against 40 healthy multiparous women without a previous history of abortion. Expression analysis of ERBB2, LIFR, STAT3 and miR-125a was conducted by quantitative real-time PCR (qPCR).

RESULTS

The expression of miR-125a was significantly lower in the plasma of RPL cases (P = 0.0001) and showed a significantly increased mean expression level in product of conception (2.56-fold, P < 0.0001). Among the target gene of miR-125a, ERBB2 and STAT3 gene expression level was significantly increased (2.58-fold, P = 0.04; 1.87-fold, P = 0.025), respectively in RPL cases while the LIFR gene revealed comparable expression (P = 0.64). Furthermore, expression analysis of ERBB2 gene with respect to its regulatory miR-125a cases depicted a significant association (P = 0.0005). Kaplan-Meier survival analysis revealed cases with low miR-125a expression had significantly shorter time to miscarriages, (log-rank P = 0.02). Also, decreased expression of miR-125a significantly conferred >2-fold increased risk for RPL (HR = 2.34: P < 0.05).

CONCLUSION

The overall conclusion of the study was that altered miR-125a expression may cause deregulation in target genes LIFR, ERBB2 and STAT3 resulting in adverse consequence in the outcome of pregnancy.

Circulating levels of cytokines (IL-6, IL-10 and TGF- β) and CD4+CD25+FOXP3+Treg cell population in recurrent pregnancy loss

Recurrent pregnancy loss (RPL), a serious reproductive health issue, characterized by two or more pregnancy losses before 20th week of gestation. Globally, it affects 2-5% couples and the basis of the crisis is still unknown in 50% cases. Successful pregnancy is associated with pro and anti-inflammatory gestational phases that tolerate the semi-allogenic foetus, and disturbance leads to pregnancy complications like RPL. This case-control study aimed to assess the inflammatory status in the mid-gestation of ongoing pregnancy of women with (RPL) and without (NRPL) the history of RPL. Blood samples were processed for PBMC isolation, subjected to Flow-cytometry for CD4+CD25+FOXP3+Treg-cell population count and serum samples for IL-6, TGF-β, IL-10 cytokine levels (ELISA). Significant reduction in the percentage of Treg cells, and elevated values for IL-6/TGF-β and IL-6/IL-10 ratios were observed in RPL over NRPL group (p = 0.0001). Opposing results were seen with respect to the magnitude of history of RPL (2 vs. >2 losses). ROC curve analysis showed the superior discriminatory ability of cytokine ratios (IL-6/TGF-β > IL-6/IL-10) for RPL over Treg cells. Our findings are suggestive of pro-inflammatory dominance in mid-gestation of pregnant women with a history of RPL in general and greater than normal anti-inflammatory milieu in cases with > 2 pregnancy loss. As both sterile and infection related inflammation plays a role in pregnancy loss, studies enrolling women with favourable and unfavourable ongoing pregnancies may shed light on the importance of the present study for developing better management/therapeutic strategies.

Novel nucleotide variations in the thrombomodulin (THBD) gene involved in coagulation pathways can increase the risk of recurrent pregnancy loss (RPL)

Recurrent pregnancy loss (RPL) is a common but complex complication in fertility conditions, affecting about 15-20% of couples. Although several causes have been proposed for RPL, it occurs in about 35-60% of cases without a known explanation. A strong assumption is that genetic factors play a role in the etiology and pathophysiology of PRL. Therefore, several genes are proposed as candidates in the pathogenesis of RPL. The current study aimed to investigate the effects of nucleotide changes in the THBD (thrombomodulin) gene as an RPL-related candidate gene. This gene encodes a cell receptor for thrombin and is involved in reproductive loss in RPL cases. Its involvement in the natural anticoagulant system has been extensively studied. By genetic screening of the entire coding and noncoding regions of the THBD gene, we found twenty-seven heterozygous and homozygous nucleotide changes. Ten of them led to amino acid substitutions, seven variants were identified in the promoter region, and eight of them occurred in 3'UTR. Potentially, the pathogenicity effects of these variations on THBD protein were evaluated by several prediction tools. The numerous genomic variations prompted noticeable modifications of the protein's structural and functional properties. Furthermore, in-silico scores were consistent with deleterious effects for these mutations. The results of this study provide genetic information that will be useful in the future for clinicians, scientists, and students to understand the unknown causes of RPL better. It may also pave the way for developing diagnostic/prognostic approaches to help treat PRL patients.

Association of inherited thrombophilia mutations and their combinations among palestinian women with unexplained recurrent miscarriage

BACKGROUND

Inherited thrombophilia (IT) has a complex pathophysiology and is associated with recurrent miscarriage (RM) by causing placental insufficiency and inhibiting fetal development. However, thrombophilia screening in unexplained RM cases is still questionable. This study aimed to investigate the association between the common eight IT mutations and their combinations among Palestinian women with unexplained RM.

METHODS

This is an unmatched case-control study with 200 women (100 unexplained RM cases, 100 controls). Eight common IT mutations namely Factor V Leiden (FVL), prothrombin gene (FII) G202120A, Methylenetetrahydrofolate Reductase (MTHFR) gene (C677T and A1298C), B-fibrinogen gene - 455G > A, FV HR2 A4070G, Plasminogen activator inhibitor 1 (PAI1) 5G/4G and Factor XIIIA (FXIIIA) V34L; were analyzed. The first five mutations were analyzed by Restriction Fragment Length Polymorphism PCR and the other three mutations were analyzed using Amplification Refractory Mutation System PCR.

RESULTS

The prevalence of the eight IT mutations among the control group was in the order PAI1 5G/4G (69%), MTHFR C677T (53%) and A1298C (47%), BFG - 455G > A (35%), FVL and FV HR2 (each 18%), FXIIIA V34L (16%) and FII G20210A (3%). Patients had a higher percentage of MTHFR A1298C (heterozygotes and mutant homozygote) compared to controls (p = 0.016). Frequencies of mutant alleles MTHFR A1298C (p < 0.001) and FXIIIA V34L (p = 0.009) were higher among patients compared to controls. No significant differences were observed for all other mutations or mutant alleles. Most patients (75%) and controls (75%) have 2-4 mutant alleles out of 8 mutant alleles studied, while 1% of patients and 2% of controls have zero mutant alleles. None of the combinations of the most often studied mutations (FVL, FII G20210A, MTHFR C1677T, and MTHFR A1298C) showed a significant difference between patients and controls.

CONCLUSIONS

There was a significant association between unexplained RM and the mutant alleles of MTHFR A1298C and FXIIIA V34L. No significant association was observed between unexplained RM and the combination of both mutant alleles for the mutations studied. This study is the first Palestinian report that evaluates eight inherited thrombophilia mutations and their alleles' combinations in unexplained RM cases.

Oxidative/nitrosative stress increased the risk of recurrent pregnancy loss-Taiwan Recurrent Pregnancy Loss and Environmental Study (TREPLES)

OBJECTIVE

Oxidative stress biomarkers (OSBs) may be strongly associated with disease progression and recurrent pregnancy loss (RPL). However, the research on associations of most OSBs (e.g., 8-nitroguanine [8-NO2Gua] and 4-hydroxy-2-nonenal-mercapturic acid [HNE-MA]) with RPL is limited. Therefore, we aimed to investigate the effect of OSBs exposure on RPL risk by performing a case-control study.

MATERIAL AND METHODS

We use our established dataset, Taiwan Recurrent Pregnancy Loss and Environmental Study (TREPLES), which included 514 Taiwanese reproductive age women (aged 20-50 years; 397 cases and 117 controls) from National Cheng Kung University Hospital. RPL is clinically defined by a history of two or more consecutive miscarriages, where a miscarriage is defined as the termination of pregnancy before 20 weeks of gestation. The urinary levels of several OSBs (e.g., 8-hydroxy-2'-deoxyguanosine [8-OHdG], 8-NO2Gua, 8-isoprostaglandin F2α [8-isoPGF2α], and HNE-MA) and malondialdehyde (MDA) were measured using isotope dilution liquid chromatography-tandem mass spectrometry and thiobarbituric acid reactive substances, respectively.

RESULTS

The median levels of 8-NO2Gua (6.15 vs. 3.76 ng/mL) and HNE-MA (30.12 and 21.54 ng/mL) were significantly higher in the RPL group than in the control group. By categorizing the OSBs data into tertiles, after we adjusted for age and urine creatinine levels discovered that the RPL risk associated with 8-NO2Gua and HNE-MA levels in the third tertile were approximately 2 times higher than those in the first tertile (8-NO2Gua, adjusted OR = 3.27, 95 % CI = 1.66-6.43; HNE-MA, adjusted OR = 1.96, 95 % CI = 1.05-3.64; p < 0.05). These findings suggest that the oxidative stress biomarkers of 8-NO2Gua and HNE-MA are risk factors for RPL.

CONCLUSION

Our findings indicate that specific OSBs are associated with an increased RPL risk, suggesting that reducing OSB levels can improve RPL risk. Nevertheless, more studies on preventive medicine are required to understand the exposure sources and adverse outcome pathways of OSBs associated with RPL.

Role of tumor necrosis factor-alpha -238 G>A promoter region polymorphism on recurrent miscarriage: An association study and meta-analysis

BACKGROUND

Recurrent miscarriage (RM) is defined as the loss of two or more consecutive pregnancies. A functional SNP, -238G>A in the promoter region of TNF-α, affects the gene transcription activity with implications on human pregnancy. Previous limited studies, linking the TNF-α -238 G>A to the risk of recurrent miscarriage have been inconclusive.

MATERIAL AND METHOD

The PCR-RLFP technique was used to evaluate this polymorphism in 199 RM cases and 215 control women from Amritsar, Punjab. For a meta-analysis, a total of 13 eligible studies (including the present study) comprising 2947 cases and 2933 controls were included. To evaluate the association among different genetic models, odds ratio with a 95% confidence interval (CI) and chi-square were used.

RESULTS

Genotype and allelic frequency did not differ significantly between both groups (p = .07 and p = .24, respectively). In the present meta-analysis, a significant association was found with the recessive model (OR-1.78 CI:1.24-2.55, p = .002).

CONCLUSION

Although, TNF-α -238 G>A polymorphism did not provide any risk in the case-control study but provided risk towards the development of RM with the recessive genetic model in the pooled analysis.