Association between polymorphic markers human leucocyte antigen-G and tumour necrosis factor alpha and susceptibility to recurrent miscarriages among Bulgarian women

Association of human leukocyte antigen-G and -F with recurrent miscarriage and implantation failure: A systematic review and meta-analysis

PROBLEM

The immune system plays an essential role in embryonic implantation and pregnancy, but the molecular details remain controversial. In the past four decades, human leukocyte antigen (HLA)-G and -F have garnered significant attention.

METHOD OF STUDY

MEDLINE, EMBASE, Web of Science, and the Cochrane Trials Registry were searched from their inception dates until December 2022. Studies were selected following PRISMA guidelines. Meta-analyses were used to assess the relationship of soluble HLA-G (sHLA-G) and HLA-G 3'-untranslated region polymorphisms with recurrent miscarriage (RM) and recurrent implantation failure (RIF). Narrative synthesis was conducted to determine the association of RM with other single nucleotide polymorphisms (SNPs) and HLA-G protein in tissues and of RIF with HLA-F. Risk-of-bias was assessed using ROBINS-I. Publication bias was assessed using Egger's and Begg's tests.

RESULTS

Finally, 42 articles were eligible for inclusion in the systematic review (32 in the meta-analysis; 13 in narrative synthesis). We found a significant association between the 14-bp ins/del HLA-G polymorphism and RM risk, but no definitive association with RIF risk. Women with RM had lower blood concentrations of sHLA-G during pregnancy and non-pregnancy than did controls. For women in the RIF group, no significant difference was found.

CONCLUSION

HLA-G protein and gene expression levels may be closely related to RM. The relevance of HLA-G to RIF is still being determined. A narrative synthesis of current studies has shown that HLA-F is likely associated with RIF.

Understanding the potential immunogenetic role of TNFα-308 polymorphism in the pathogenesis of recurrent miscarriage

Background

Recurrent miscarriage (RM) represents the spontaneous termination of two or more successive pregnancies. TNFα is a proinflammatory cytokine that is often considered harmful for embryonic development when expressed beyond normal levels.

Aim

The study was conducted to assess the association between TNFα-308 polymorphism and RM pathogenesis.

Methods

Samples of blood were obtained from patients and controls through venipuncture. The levels of TNFα in serum were measured by ELISA. TNFα gene promoter-associated single-nucleotide polymorphism was investigated with polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) techniques with precise primers and the restriction endonuclease, NcoI.

Results

Serum TNFα levels in patients were considerably high (p < 0.05) than controls. The genotype and allele frequencies for TNFα gene polymorphism differs significantly (p = 0.0089; p = 0.0043 respectively) between patients and controls. The TNFα-308 SNP exhibited a link with higher RM risk in heterozygous (GG vs. GA; OR: 3.086, 95% CI: 1.475-6.480; p: 0.0027), dominant (GG vs. GA + AA; OR: 2.919, 95% CI: 1.410-6.056, p: 0.0038), and allelic/codominant (G vs. A; OR: 2.449, 95% CI: 1.313-4.644, p: 0.0064) models. However, this SNP showed an insignificant association with higher and lower RM risk in homozygous (GG vs. AA; OR: 1.915, 95% CI: 0.3804-10.99, p: 0.6560) and recessive (AA vs. GA + GG; OR: 0.6596, 95% CI: 0.1152-3.297, p: >0.9999) models, respectively. Further, the TNFα-308G/A genotype frequencies were in concord with HWE both in the controls (χ² = 3.235; p = 0.1985) and the patients (χ² = 0.0117; p = 0.9942).

Conclusion

The serum TNFα levels were significantly higher in the patients than the controls. The genotyping analysis also demonstrated that TNFα-308G/A SNP significantly increases the overall risk of RM, suggesting that the SNP modulates the TNFα gene expression and thereby increases serum TNFα levels that adversely affect the pregnancy outcome.

Role of polymorphisms on the Recurrent Pregnancy Loss: A systematic review, Meta-analysis and bioinformatic analysis

Recurrent miscarriage (RM) is a major reproductive health issue. RM is a multi-factorial disease, and is affected by environmental, genetic, and epigenetic factors. Genetics has a common role in recurrent miscarriage occurrence. It seems that molecular genetics has a great role in RSA incidence. So, in these years, RM has become for a major subject of genetics research. There are many genes that are involved in each phase for successful reproduction. This research aimed to evaluate the effect of all studied polymorphisms in studies on RSA that have not been included in any meta-analysis. PubMed, Scopus, and Web of Science databases were recruited to investigate the related articles. The systematic review results identified 143 studies worldwide. Thirteen genes have been included in assessing the case-control studies. Sixty-four SNPs were recruited to assess the association between genetic factors and RSA susceptibility. Ninety-two studies containing twenty two SNPs (from 10 genes) were included in the quantitative analysis. Bioinformatic analysis indicated that rs12722482 showed "Damaging Status" by double servers, and rs315952 and rs854560 had "Possibly damaging" status in the PolyPhen-2 server. MethPrimer server indicated that there is "CpG Island" in the rs10895068, rs1130355, and rs41557518 variants, and rs10895068-G allele makes a CpG dinucleotide which can change the gene methylation and result in altering the gene expression. So, further studies on rs12722482 and rs10895068 can demonstrate valuable results. To the best of our knowledge, this systematic review has covered the all studied polymorphisms of HLA-C, HLA-G, PON1, AGTR1, TAFI, FAS, FAS-L, ESR1, PGR, CTLA-4, MMP-2, MMP-3, MMP-9, and IL1RN for the first time. Also, we did a novel meta-analysis for AGTR1 rs5186, TAFI rs1926447, rs3742264, HLA-G rs1063320, rs1233334, rs1736936, rs2249863, PON1 rs662, rs854560, FAS rs2234767, rs1800682, FAS-L rs763110, ESR1, rs9340799, rs3798759, PGR rs1042838, CTLA4 rs4553808, rs5742909, rs231775, rs3087243, and MMP-2 rs243865 and updated statistical finding for rs2234693 and rs371194629. Rs2234693, rs9340799, rs231775, and rs371194629 demonstrated a significant association with RSA risk. Some variations showed significant association, while further studies are suggested to confirm the results. Finally, Rs4553808 and rs5742909 revealed no significant deviation in the results. It is suggested that these SNPs may be excluded from subsequent case-control studies or other analyses.