Influence of prominent immunomodulatory cytokines TNF-α308 G>A (rs1800629) and TGFβ1 G>C (rs1800471) sequence variations as an important contributing factor in etiopathogenesis of recurrent miscarriages in Kashmiri women (North India)

Association between cytokine polymorphisms and recurrent pregnancy loss: A review of current evidence

Cytokines are a type of protein that play an important role in the immune response and can also affect many physiological processes in the body. Cytokine polymorphisms refer to genetic variations or mutations that occur within the genes that code for cytokines, which may affect the level of cytokine production and function. Some cytokine polymorphisms have been associated with an increased risk of developing certain diseases, while others may be protective or have no significant effect on health. In recent years, the role of cytokine polymorphisms in the development of recurrent pregnancy loss (RPL) has been studied. RPL or miscarriage is defined as the occurrence of two or more consecutive pregnancy losses before the 20th week of gestation. There are diverse causes leading to RPL, including genetic, anatomical, hormonal, and immunological factors. With regard to cytokine polymorphisms, a few of them have been found to be associated with an increased risk of RPL, for instance, variations in the genes that code for interleukin-6, tumor necrosis factor-alpha, and interleukin-10. The exact mechanisms by which cytokine polymorphisms affect the risk of recurrent miscarriage are still being studied, and further research is essential to fully understand this complex condition. This brief review aims to summarize the recent literature on the association between cytokine polymorphisms and RPL.

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.