Study on potential role of apolipoprotein E in recurrent pregnancy loss

APOE-E4 allele as a potential marker for implantation failure: A comparison between fertile women, ART success and RIF patients

OBJECTIVE

Apolipoprotein E (APOE) is the most important precursor for the production of steroid hormones and is also involved in regulating the function of steroid hormones, hence playing a significant role in reproductive processes. So, APOE gene expression may be correlated with the implantation process. This study tries to make a better clarification of the correlation between APOE gene polymorphisms and recurrent implantation failure (RIF), where we compared the frequency of APOE polymorphisms in RIF patients, assisted reproductive treatment (ART) success cases and fertile women.

METHOD

In all, 100 women with successful ART who got pregnant (fetal heart rate positive) in their first or second cycle of in vitro fertilization or intracytoplasmic sperm injection, 100 infertile RIF cases, and 100 normal fertile control cases with at least one live birth were included in present study. Following DNA extraction, genotypes were determined through polymerase chain reaction-restriction fragment length polymorphism method using HhaI restriction enzyme. Finally, statistical analysis was performed by chi-squared (χ2) test in SPSS software (P < 0.05).

RESULTS

The RIF group showed significantly higher frequency for E3/E4 genotype (29%) compared with the other two control groups (fertile = 15%, ART success [ART+] = 13%) (P = 0.007). There was also a significantly higher frequency of the E4 allele in the RIF group (14.5%) compared with both of the control groups (fertile = 7.5%, ART+ = 6.5%) (P = 0.018).

CONCLUSION

APOE4 is correlated with recurrent failure in the process of embryo implantation and, accordingly, it may potentially be considered a possible risk factor to the implantation process. The presence of E4 can be proposed as a predictive indicator in determining the results of assisted reproductive techniques.

PI3K/AKT signaling alters glucose metabolism in uterine microenvironment of women with idiopathic recurrent spontaneous miscarriage

BACKGROUND

This study aims to identify metabolomic signatures in uterine fluid of women with idiopathic recurrent spontaneous miscarriage (IRSM) during window of implantation (WOI). Also, glucose transporters GLUT3 and GLUT4 and proteins of PI3K-Akt signaling pathway in endometrial tissue are assessed.

METHODS

Paired uterine fluid and endometrial biopsies were collected during WOI from women with IRSM (n = 24) and healthy women with azoospermic male partners as controls (n = 15). NMR metabolomics was used to identify the dysregulated metabolites in uterine fluid of IRSM women. Additionally, proteins and glucose transporters were investigated in the endometrial tissue using immunohistochemistry (IHC) and western blotting.

RESULTS

Uterine fluid metabolomics indicated eleven metabolites to be significantly downregulated in IRSM. While expression levels of PI3K (p85), PI3K (p110), p-Akt (Thr308), p-Akt (Ser473), GLUT3 and GLUT4 were significantly downregulated in endometrial tissue of these women, p-IKK α/β (Ser176/180) and p-NFkBp65 (Ser536) were significantly increased.

CONCLUSION

Our findings suggest that dysregulation of PI3K/Akt pathway in the uterine microenvironment could be a likely cause of endometrial dysfunction, thereby affecting implantation. Further studies on the downstream effects of the Akt signaling pathway in-vitro for improved understanding of the Akt-mediated cellular responses in IRSM is, therefore, warranted.

Maternal ApoE genotype and risk of recurrent pregnancy loss: An updated systematic review and meta-analysis

BACKGROUND

In order to clarify the role of the maternal apolipoprotein E (ApoE) genotype and the risk of recurrent pregnancy loss (RPL), we herein performed an updated systematic review and meta-analysis to reevaluate the evidence on this association.

METHODS

A comprehensive literature search was performed on PubMed, Web of Knowledge and the Cochrane library up to September 2022. Methodological study quality was assessed using the Newcastle-Ottawa Scale and the credibility of significant pooled odds ratios (ORs) was estimated by the false positive report probability and the Bayesian false discovery probability.

RESULTS

Twelve studies published from 2009 to 2022 fulfilled the inclusion criteria. In the overall analysis, the ε4 allele was found to confer an increased risk of RPL compared to the ε3 allele (OR 1.60, 95% CI 1.00-2.55, p = 0.049) and women carrying the ApoE ε4 allele displayed a higher risk of RPL compared with those carrying the ε2 and ε3 alleles (OR 1.75, 95% CI 1.06-2.87, p = 0.028). Subgroup analysis based on subjects' ethnicity revealed that these associations were restricted to the Asian population (ε4 allele vs. ε3 allele, OR 5.93, 95% CI 1.79-19.61, p = 0.004; ε4 allele carriers vs. carriers of ε2 and ε3 alleles, OR 8.42, 95% CI 1.47-48.12, p = 0.017). None of the associations detected were found to be noteworthy under false positive report probability or Bayesian false discovery probability at a prior probability of 0.001.

CONCLUSIONS

This updated meta-analysis highlights an association between maternal ApoE genotype and RPL risk in Asians, but not in Caucasians. Further case-control studies are warranted in women of Asian ancestry to exclude the possibility of false-positive findings.

Maternal Thrombophilic and Hypofibrinolytic Genetic Variants in Idiopathic Recurrent Pregnancy Loss: a Continuing Mystery

Despite the fact that multiple recurrent pregnancy loss (RPL) etiologies have been identified, 50-70% of RPL cases remain enigmatic, and idiopathic RPL is still a serious medical challenge. A plethora of studies have investigated the correlation of RPL with variations in coagulation and/or fibrinolytic factors-encoding genes. Notwithstanding, evidence for a link between these variations and RPL remains discordant. We aimed to explore the association of thrombophilic and hypofibrinolytic gene variations with RPL development. Two hundred Saudi women were recruited in this study, comprising 150 women experiencing RPL and 50 healthy women. Thirteen genetic variants, including FV G1691A, FV A4070G, F2 G20210A, F13A1 G103T, FGB - 455G > A, PAI-1 - 675 4G/5G, ITGB3 T1565C, MTHFR C677T, MTHFR A1298C, ACE I/D, APOB G10708A, APOE T388C, and APOE C526T were genotyped using ViennaLab StripAssay. Women experiencing RPL harbor significantly higher frequencies of the F13A1 103 T, FGB - 455A, and ITGB3 1565C alleles than control women (p < 0.001). No differences in the prevalence of other investigated variants were identified between control women and those with RPL. No considerable link of F5 1691G > A/4070A > G, MTHFR 677C > T/1298A > C, and APOE 388 T > C/526C > T haplotypes with RPL risk was demonstrated. F13A1 G103T, FGB - 455G > A, and ITGB3 T1565C variants are connected to a higher likelihood of developing RPL and, hence, may have the potential to identify those women at risk of RPL, thereby, improving RPL susceptibility prediction. Incorporating molecular testing of thrombophilic and hypofibrinolytic genetic variants into routine workup could confer a promising approach for refined RPL risk assessment.

Putative Survival Advantages in Young Apolipoprotein ɛ4 Carriers are Associated with Increased Neural Stress

Inheritance of a single copy of the apolipoprotein E (APOE) ɛ4 allele increases risk of Alzheimer’s disease (AD) by 3-4-fold, with homozygosity associated with a 12-16-fold increase in risk, relative to ɛ3 allele homozygosity. There is a decreased risk associated with the APOE ɛ2 allele. The pathological consequence of APOE genotype has led to intense efforts to understand the mechanistic basis of the interplay between APOE status and loss of synapses. Numerous ɛ4 allele-related associations have been reported with the potential relevance of these associations to the pathogenesis of AD unknown at this time. In primarily young subjects, we have reviewed a representative body of literature on ɛ4 allele-associations related to the following: cardiovascular responses; impacts on reproduction and fetal development; co-morbidities; resistance to infectious disease; responses to head injury; biochemical differences possibly related to neural stress; and brain structure-function differences. In addition, the literature on the association between the ɛ4 allele and cognitive performance has been reviewed comprehensively. The weight-of-the-evidence supports the hypothesis that possession of the ancestral ɛ4 allele in youth is associated with improved fitness during fetal development, infancy, and youth relative to the more recently appearing ɛ3 allele, at the expense of decreased fitness in old age, which is substantially improved by the ɛ3 allele. However, possession of the ɛ4 allele is also associated with higher levels of synaptic macromolecular turnover, which likely stresses basic cellular neuroplasticity mechanisms. Clinical trials of potential AD therapeutics should consider APOE status as an enrollment criterion.

Prevalence of candidate single nucleotide polymorphisms on p53, IL-11, IL-10, VEGF and APOE in patients with repeated implantation failure (RIF) and pregnancy loss (RPL)

Recurrent pregnancy loss (RPL; defined as the loss of three or more consecutive pregnancies) and recurrent implantation failure (RIF; when implantation is not achieved after at least three cycles of IVF) are two of the major challenges that reproductive medicine faces. Some polymorphisms have been identified as possible causes of an increased risk of these diseases. This paper studies the prevalence of the polymorphisms in p53, VEGF, IL-10, IL-11 and APOE in RIF and RPL patients that determines the risk for these pathologies. A total of 255 patients were selected (89 RPL patients, 77 RIF patients and 89 controls) and genotyped for p53-R72P; IL-11-1082-AG; VEGF-1154-AG; IL-10; APOE-R112C; APOE-R158C. Statistically significant differences were found in the prevalence of the E4 isoform (R122-R158) of the APOE gene in RPL patients (p < 0.05), and in RIF patients, the R72P polymorphism of the p53 gene and the 1154-AG of the VEGF gene showed different distribution (p < 0.05). Regarding the p53 and IL-11 studied polymorphisms, PP of p53 gene and GG of IL-11 are more prevalent in RPL patients without reaching statistical significance. In conclusion, our results suggest patients carrying variants in p53 and VEGF would be at risk of RIF, and those carrying variants in APOE gene would suffer RPL.

Comparison of two groups for the apolipoprotein E polymorphisms by using next generation sequencing: The first group with three consecutive abortions and the second group with at most one abortion in three consecutive pregnancies

The importance of apolipoprotein E genotypes and allelic polymorphisms in the etiology of recurrent miscarriage is controversial. We plan to investigate this in a two-group study involving more than a thousand participants. In total, 1046 subjects (802 participants in the first group, 244 participants in the second group) were investigated. Women in the first group had a history of ≥3 consecutive spontaneous miscarriage and women in the second group had at most one miscarriage in three consecutive pregnancies. The participants with the following evidence and symptoms were excluded from both groups; structural uterine abnormality, chrosomal abnormalities and polymorphisms, hormonal imbalance, anti-nuclear antibodies, anti-phospholipid antibodies, lupus anticoagulant and homozygous genotype for FV-Leiden, MTHFR C677T, MTHFR A1298C, prothrombin 20210G>A and plasminogen activator inhibitor 4G/5G polymorphisms. We found similar apolipoprotein E allelic frequencies and genotype distributions in both groups. The frequencies of ε2 alleles were 4.1% in the first group and 2.9% in the second group, whereas those of ε3 alleles were 90.8% and 93% in the first group and the second group, respectively and ε4 alleles were 5.1% in the first group and 4.1% in the second group. The genotypes of Apo E observed in the first and the second group respectively were as follows; ε2/ε3 (7.5% and 5.7%), ε3/ε3 (82.7% and 86.5%), ε3/ε4 (8.7% and 7.4%), ε4/ε4 (0.5% and 0.4%) and ε2/ε4 (0.6% and 0). Our data did not support a possible association between apolipoprotein E genotypes and allelic frequencies, and recurrent miscarriages. We believe that the studies excluding the etiological factors that were previously found to be related with any condition are more valuable in the scope of showing the cause-effect relationship.

The association between cardiovascular disease gene mutations and recurrent pregnancy loss in the Lebanese population

Recurrent pregnancy loss (RPL) is a problem affecting up to 5% of women of childbearing age due to many factors. Studies have shown that RPL and cardiovascular disease (CVD) may have shared risk factors. We compared the prevalence of 12 cardiovascular disease related gene mutations in patients with a history of RPL to normal controls in a major tertiary care center in Lebanon. The CVD StripAssay (ViennaLab, Austria) was used to analyze the CVD genes on 70 women with RPL history as part of the initial routine workup for recurrent miscarriage at the American University of Beirut Medical Center. The obtained results were compared with data of controls from the Lebanese population using Fisher's exact test and Chi square analysis. Two genes of the CVD panel demonstrated a strong relationship with RPL, including, MTHFR (C677T homozygosity, A1298C homozygosity, and compound heterozygosity for C677T and A1298C) and Factor II (heterozygosity for G20210A). Moreover, a protective role of positive APO-E3 isoform was observed. This study is the first in the Lebanese population in associating RPL with a large panel of CVD related genes.

First Bosnian Study of the Relationship between APOE rs7412 and rs429358 Variants and Pregnancy Loss

Due to inconsistent results of APOE variants in the survival of pregnancy we investigated the potential relationship of APOE rs7412 and rs429358 with pregnancy loss (PL) in Bosnian women. We enrolled 154 women with PL. The minimum week of miscarriage was 6, while the maximum was 28. As a control group, an equal number of mothers with at least one live-born child was included. All women were recruited from the Institution of Health Protection of Women and Motherhood in Sarajevo, Bosnia and Herzegovina. Genotyping was performed by real- time PCR at the Department of General Pharmacology and Pharmacoeconomics, Pomeranian Medical University. The prevalence of genotypes E2/E3, E2/E4, E3/E3, E3/E4, E4/E4 in the group with and without PL were: 14.3 %, 1.3 %, 70.8 %, 12.3 %, 1.3 %, and 13.6 %, 1.3 %, 70.1 %, 14.3 %, 0.7 %, respectively. The frequency of the E4/E4 genotype in women with 1-2 and 3-4 PL compared to women without PL did not differ significantly between those three groups (P value = 0.0712). The frequencies of alleles ԑ2, ԑ3, ԑ4 in the group with and without PL were: 6.8 %, 85.1 %, 8.1 % and 7.5 %, 84.1 %, 8.4 %, respectively, and did not differ significantly. We conclude that our study does not confirm rs7412 and rs429358 as a potential risk factor for PL in the studied group. To elucidate the relationship between PL and variants of the APOE gene, studies with a larger sample size and placental histomorphology and genetic diagnosis are required.

Thrombophilic gene polymorphisms and recurrent pregnancy loss in Greek women

INTRODUCTION

Recurrent pregnancy loss (RPL) is a multifactorial disorder. The aim of this study was the detection of various genetic polymorphisms and their correlation to RPL, in Greek women.

METHODS

The impact of 12 thrombophilic polymorphisms was evaluated, among 48 Greek women with a history of RPL, vs 27 healthy parous women. Multiplex PCR and in situ hybridization on nitrocellulose films were performed, to investigate 12 genetic polymorphisms previously reported as risk factors for RPL.

RESULTS

Heterozygous FV Leiden, homozygous PAI-1 4G/4G, heterozygous MTHFR C677T, homozygous MTHFR A1298C, as much as the combined thrombophilic genotypes MTHFR 677T + ACE Ι/D, MTHFR 677T/1298C + ACE D/D, ACE I/D + b-fibrinogen -455 G/A, FV HR2 + b-fibrinogen -455 G/A showed a correlation as risk factors for RPL, whereas the rest of the investigated polymorphisms and their combinations did not render statistically significant differences between the two groups in study.

CONCLUSION

The results of this study, as well as those of similar studies, concerning the detection of genetic, environmental, and physiological factors underlying RPL, will prove of critical significance in the investigation and treatment of thrombophilic predisposition, in cases of RPL.

Interaction of apolipoprotein E gene polymorphisms on miscarriage risk in black and white American women

OBJECTIVE

To evaluate whether [1] apolipoprotein E (APOE) polymorphisms can differentially regulate miscarriage risk and [2] whether this genotype effect could also be modulated by the race within populations.

DESIGN

Data were derived from the Coronary Artery Risk Development in Young Adults (CARDIA), a longitudinal study with black and white participants from four U.S.

SETTING

Not applicable.

PATIENT(S)

Women without miscarriages (controls) and women who miscarried at least once (cases).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

A group of women (n = 1,372) successfully followed for 25 years and with their APOE alleles identified were analyzed for miscarriage risk throughout their reproductive life. Additionally, a larger longitudinal analysis encompassing all the participants who had their APOE characterized (n = 2,140) was also performed for the association between APOE and miscarriage risk.

RESULT(S)

In white women followed up for 25 years, the odds ratio for miscarriage associated with APOE*2 allele presence was 1.61 (95% confidence interval, 1.04-2.50) compared with APOE*33 carriers. This was a race-dependent phenomenon as no associations between APOE alleles and miscarriage was observed in black women. Likewise, Cox regression analysis showed that cumulative miscarriage risk in white women was 37.2% in the APOE*2 carriers compared with 27.8% and 24.8% in APOE*33 and APOE*4 carriers, respectively. With APOE*33 as the reference, the age-adjusted hazard ratio associated with carrying the APOE*2 allele was 1.47 (95 confidence interval, 1.06-2.05).

CONCLUSION(S)

This variable miscarriage risk, produced by an interaction between genotype and race, may reconcile, at least partially, the conflicting reports of the association of APOE and miscarriage risk.

Apolipoprotein E genotyping in women with recurrent pregnancy loss: an in silico and experimental hybrid study

The role of apolipoprotein E gene polymorphisms in the pathogenesis of recurrent pregnancy loss remains controversial. Therefore, our objective was to investigate the association between recurrent pregnancy loss and apolipoprotein E gene polymorphisms among northwest Iranian women, and also to predict the impact of these nonsynonymous single nucleotide polymorphisms on structure and function of apolipoprotein E protein. The subjects of our current study consisted of 100 women that have had two or more consecutive idiopathic first trimester miscarriages, and one hundred healthy women from the same geographical areas were used as a control group. After DNA extraction, we used a polymerase chain reaction-restriction fragment length polymorphism to genotype of the apolipoprotein E gene. In addition, we predicted the possible effects of amino acid substitutions at codons 112 and/or 158 on the structure and function of apolipoprotein E protein using Polymorphism Phenotyping online software v2. Our results showed that the rate of apolipoprotein E ε4 carriers and the frequency of the ε4 allele in the case group were statistically and significantly higher than those in the control group (P<0.05). Therefore, our data support the association of the Apo ε4 allele with RPL; however, in silico analysis predicted that the amino acid substitution at residue 112 (Apo ε4 allele) is a benign mutation. Accordingly, further studies are required to elucidate the mechanism(s) underlying the link between RPL pathogenesis and the Apo ε4 allele.

Association between apolipoprotein E gene polymorphism and the risk of recurrent pregnancy loss: a meta-analysis

PURPOSE

The association between apolipoprotein E (ApoE) gene polymorphism and the risk of recurrent pregnancy loss (RPL) remains controversial. The present meta-analysis was performed to derive a precise estimate of the relationship.

METHOD(S)

We searched the PubMed, Embase, and Web of Science data- bases for studies related to the association between the ApoE genotype and the risk of RPL. We estimated the summary odds ratio (OR) with 95% confidence interval (CI) to assess the association.

RESULT(S)

Seven studies, including 2,090 RPL cases and 742 control samples, were identified. The results showed a significant association between ApoE E4 mutation and RPL risk (for E4 allele: OR =1.98, 95 %CI =1.14-3.43, P=0.499; for E2E3 vs. E3E3: OR =1.33, 95%CI =1.12-1.42, P=0.008; for E2E4 vs. E3E3: OR =1.26, 95 % CI =1.07-1.49, P=0.005).

CONCLUSION(S)

The meta-analysis suggests an association between ApoE E4 mutation and increased risk of RPL.