Polymorphisms in interleukin genes and their association with the risk of recurrent pregnancy loss

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.

Maternal candidate gene variants, epigenetic factors, and susceptibility to idiopathic recurrent pregnancy loss: A systematic review

BACKGROUND

Recurrent pregnancy loss is defined as the loss of two or more pregnancies and is a distressing condition for couples.

OBJECTIVE

To investigate the relationship between variants in the candidate susceptibility genes and epigenetic factors to identify risk factors for idiopathic recurrent pregnancy loss (iRPL).

SEARCH STRATEGY

A systematic literature search was performed using PubMed, Google Scholar, ScienceDirect, and Scopus databases. Insilico analysis was carried out using ShinyGO and STRING software.

SELECTION CRITERIA

Research papers examining the association between variations in genetic and epigenetic factors and iRPL.

DATA COLLECTION AND ANALYSIS

Data were independently extracted by two authors.

MAIN RESULTS

In total, 83 research papers were finally selected for the present study. Among all the genes involved in the pathogenesis of recurrent pregnancy loss, polymorphisms in IL superfamily genes, VEGF, ESR, and MTHFR were the most investigated.

CONCLUSION

Polymorphisms in angiogenesis, immune tolerance, and thrombophilia pathway genes, which occur independently or synergistically, may lead to various complications during fetal development. Identification of multi-allele risk variants and epigenetic factors in women will be helpful in the identification of high-risk pregnancies.

PROSPERO REGISTRATION NUMBER

Prospero CRD42021287315.

Association of the IL-6 gene rs1800796 polymorphism with recurrent pregnancy loss in a population of women from northwestern China: a case-control study

We aimed to identify whether IL-1β (rs1143627, rs1143634 and rs16944), IL-6 (rs1800796), IL-10(rs1800872 and rs1800896), and vascular endothelial growth factor (VEGF) (rs1570360) gene polymorphisms were risk factors for recurrent pregnancy loss (RPL) in a population of women in northwestern China. A total of 150 women with a history of two or more unexplained and consecutive spontaneous abortions before their 24th gestational week and 150 age-matched women with at least two normal pregnancies and no history of pregnancy loss were included in the present study as cases and controls, respectively. We extracted genomic DNA from peripheral blood, and executed genotyping with the SNaPshot technique. Logistic regression analysis was conducted to determine the odds ratios (ORs) of the associations between the polymorphisms and RPL. Of the seven polymorphisms we studied, only IL-6 rs1800796 showed a statistically significant association with RPL, as we noted an elevated risk of RPL with the G allele (OR = 1.57; 95% CI, 1.10-2.24; p = .01). The risk of RPL in women with the GG + CG genotype (OR = 1.96; 95% CI, 1.19-3.21; p = .01) was also higher than that in women with the CC genotype. The present study thus indicated that the IL-6 gene rs1800796 polymorphism may serve as an important risk factor for RPL in this group of women from northwestern China.IMPACT STATEMENTWhat is already known on this subject? Cytokine and vascular endothelial growth factor (VEGF) gene polymorphisms may affect the risk of recurrent pregnancy loss (RPL) by modulating cytokine and VEGF expression.What do the results of this study add? The study results showed that the IL-6 rs1800796 single-nucleotide polymorphism constituted a risk factor for RPL in a population of women in northwestern China.What are the implications of these findings for clinical practice and/or further research? This study clearly reflects clinical significance as it provides a theoretical basis for the early screening of RPL by revealing that the IL-6 gene rs1800796 polymorphism increased the risk of RPL in women in northwestern China.

The Role of TNF-α and Anti-TNF-α Agents during Preconception, Pregnancy, and Breastfeeding

Tumor necrosis factor-alpha (TNF-α) is a multifunctional Th1 cytokine and one of the most important inflammatory cytokines. In pregnancy, TNF-α influences hormone synthesis, placental architecture, and embryonic development. It was also shown that increased levels of TNF-α are associated with pregnancy loss and preeclampsia. Increased TNF-α levels in complicated pregnancy draw attention to trophoblast biology, especially migratory activity, syncytialisation, and endocrine function. Additionally, elevated TNF-α levels may affect the maternal-fetal relationship by altering the secretory profile of placental immunomodulatory factors, which in turn affects maternal immune cells. There is growing evidence that metabolic/pro-inflammatory cytokines can program early placental functions and growth in the first trimester of pregnancy. Furthermore, early pregnancy placenta has a direct impact on fetal development and maternal immune system diseases that release inflammatory (e.g., TNF-α) and immunomodulatory factors, such as chronic inflammatory rheumatic, gastroenterological, or dermatological diseases, and may result in an abnormal release of cytokines and chemokines in syncytiotrophoblasts. Pregnancy poses a challenge in the treatment of chronic disease in patients who plan to have children. The activity of the disease, the impact of pregnancy on the course of the disease, and the safety of pharmacotherapy, including anti-rheumatic agents, in pregnancy should be considered.

Relationship between common interleukin 1-beta gene polymorphisms and the risk of gestational disorders: An updated meta-analysis

Background: To quantitatively estimate the relationship between IL-1β -511C>T, -31T>C, and +3954C>T polymorphisms and risk of gestational disorders. Methods: In this meta-analysis, eligible publications were searched in Web of Knowledge, MEDLINE, PubMed, Scopus, and Google Scholar databases (updated April 2020), using appropriate or relevant keywords. Case-control population-based reports were included if provided with genotypic frequencies of both studied groups. Statistical analyses were performed using the MetaGenyo web tool software, where a P value less than 0.05 indicated a significant association. For the assessment of between-study variations, heterogeneity analysis was applied with the I² statistics. Results: A total of thirteen studies were included. We observed a significant association between IL-1β-31T>C polymorphism and reduced risk of gestational disorders under codominant CT vs. CC [OR= 0.74, CI (0.59-0.92)], and dominant CT+TT vs. CC [OR= 0.74, CI (0.60-0.91)] contrasted genetic models. The stratified analysis considering the disease type showed that the 511C>T variant, under the recessive CC vs. CT+TT model, enhanced the risk of preterm birth by 1.29 fold. Conclusion: Our results failed to support an association between two IL-1β polymorphisms, 511C>T and +3954C>T, with the overall risk of gestational disorders. In contrast, the 31T>C variant reduced the incidence of such diseases. Further studies are encouraged to get more precise estimates of effect sizes.

Evaluation of IL1B rs1143634 and IL6 rs1800796 Polymorphisms with Autism Spectrum Disorder in the Turkish Children

Background: Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder caused by genetic, environmental and immunological factors. It is known that neural development processes are affected by immune functions. The aim of this study is to evaluate the relationship between cytokines IL6 and IL1B gene polymorphisms in ASD.Methods: DNA isolations were performed in 95 children diagnosed with ASD and 84 unrelated healthy children, single-nucleotide changes in IL6 (rs1800796) and IL1B (rs1143634) genes were determined by using Real-Time PCR (Real-Time Polymerase Chain Reaction) method.Results: IL6 rs1800796 polymorphism presented an elevated risk for the development of ASD with CG genotype and dominant model (CG+GG vs. CC), CG+GG carriers (OR = 1.867, p = 0.057; OR = 1.847, p = 0.055, respectively). CT genotype in IL1B rs1143634 polymorphism associated with 2.33 times elevated risk of autism and showed a significant association compared to wild-type CC genotype (p = 0.02). IL1B rs1143634 polymorphism presented a significantly elevated risk for the development of ASD with recessive model (CC+CT vs.TT), TT genotype (OR = 8.145, p = 0.02).Conclusion: This study concludes that rs1143634 is associated with the risk of ASD in Turkish children. Determining these polymorphisms in a larger sample group may contribute to understanding the etiology of ASD and developing new treatment protocols.Abbreviations: ASD: Autism spectrum disorder; DNA: Deoxyribonucleic acid; IL6: Interleukin 6; IL1B: Interleukin 1 beta; Real-time PCR: Real-time polymerase chain reaction; JAK-STAT: The Janus kinase/signal transducers and activators of transcription; MAPK: The mitogen-activated protein kinase; 5'UTR: The 5' untranslated region; IL1α: Interleukin 1 alpha; IL-1Ra: Interleukin 1 receptor antagonist; NF-κB: Nuclear factor-kappa B; DSM-V: The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition; M-CHAT: Modified Checklist for Autism in Toddlers; EDTA: Ethylenediaminetetraacetic acid; gDNA: Genomic DNA; HWE: Hardy-Weinberg equilibrium; ANK2: Ankyrin 2; NL3: Neuroligin-3; XRCC4: X-ray repair cross complementing 4.