Cytokine gene polymorphisms and susceptibility to recurrent pregnancy loss in Iranian women

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.

Genes of Inflammation and Placental Function GWAS Associated with Idiopathic Recurrent Miscarriage in the Kazakh Population

Background

The loss of two or more pregnancies is considered recurrent miscarriage (RM). One of the causes of this pathology is the occurrence of mutations both in pleiotropic and pathway-specific regulators and in structural genes. The simplest type of such mutations is single nucleotide polymorphisms.

Aims

The aim of the study is to study the relationship between gene polymorphisms of anti- and pro-inflammatory cytokines - interferon-gamma (T874A), interleukin (IL1B) (C3954T), IL6 (G572C) and IL10 (G1082A); placental function, apoptosis and angiogenesis - apolipoprotein C-III (APOC3) (G5163C), kinase insert domain receptor (A1719T, G1192A), P53 (Arg72Pro) and signal transducer and activator of transcription 3 (STAT3) (C1697G) with the development of idiopathic RM (iRM) in the Kazakh population.

Settings and Design

This was a case-control study.

Materials and Methods

Molecular genetic studies were performed by TaqMan using a single site-specific amplification and real-time genotyping method in 302 women with iRM and 300 with normal reproduction. DNA isolation from the biomaterial was carried out using kits containing binding magnetic particles. Both samples were analysed for alleles and genotypes for the studied polymorphisms.

Statistical Analysis Used

For statistical data processing, Pearson's criterion, confidence interval (CI) and probability value were taken into account.

Results

It was found that the carriage of unfavourable genotypes (G/C, C/C) for the G5163C polymorphism of the APOC3 gene increases the risk of developing iRM by three times (odds ratio = 3.0; 95% CI = 2.24-4.07). Other studied polymorphisms in the genes of ILs, interferon, P53 proapoptotic protein, kinase domain receptor and STAT3 transcription activator were not associated with RM.

Conclusion

Significant associations of APOC3 gene genotypes with the development of iRM in the Kazakh population indicate the involvement of the placental system, which is realised by vascularisation defects and defective embryo implantation and leads to early pregnancy termination.

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.

Impact of Interleukin-10 Promoter Region Polymorphisms on Recurrent Miscarriage: A Case-Control Approach

Background

Recurrent miscarriage (RM), defined as two or more consecutive miscarriages prior to the 20th week of gestation is characterised by multifactorial aetiology. The prevalence of RM varies from 0.8% to 13.5% amongst women of reproductive age. The aetiological basis of RM has been traced to chromosomal, anatomic, hormonal and immunologic factors while half of the cases remain idiopathic.

Aims

This study aimed to investigate the association of interleukin-10 (IL-10) polymorphisms with RM amongst the Indian population.

Settings and Design

The present study included a total of 414 individuals including RM women (n = 199) with two or more pregnancy losses and healthy women (n = 215) without any previous history of pregnancy loss were taken as the control group.

Materials and Methods

Demographic features and reproductive history of women with RM and healthy women were taken. Genotype analysis of IL-10 polymorphisms rs1800872 and rs1800896 was performed using the polymerase chain reaction (PCR) restriction fragment length polymorphism and amplification mutation refractory system PCR, respectively.

Statistical Analysis Used

Student's t-test was used to compare the demographic features and reproductive history amongst both groups. Pearson's Chi-square was used to calculate the Hardy-Weinberg equilibrium, allelic and genotypic frequencies. All the statistical analyses were performed using the SPSS (version 21, IBM SPSS, NY, USA).

Results

Our results suggested that the genotypic and allelic frequency of rs1800872 polymorphism did not differ significantly between RM cases and control women (P = 0.07 and P = 0.23, respectively). The GG genotype (P = 0.007) and G allele (P = 0.003) of rs1800896 were significantly associated with an increased risk of RM. A statistically significant difference was also found for the distribution of genetic models (dominant and co-dominant model) between both groups for rs1800896. However, haplotype analysis revealed that none of the haplotypes provides a risk for the progression of RM.

Conclusion

The study is the first of its kind from our region and provides baseline data on the genetics of RM.

The Update Immune-Regulatory Role of Pro- and Anti-Inflammatory Cytokines in Recurrent Pregnancy Losses

Recurrent pregnancy losses (RPL) is a common reproductive disorder with various underlying etiologies. In recent years, rapid progress has been made in exploring the immunological mechanisms for RPL. A propensity toward Th2 over Th1 and regulatory T (Treg) over Th17 immune responses may be advantageous for reproductive success. In women with RPL and animals prone to abortion, an inordinate expression of cytokines associated with implantation and early embryo development is present in the endometrium or decidua secreted from immune and non-immune cells. Hence, an adverse cytokine milieu at the maternal-fetal interface assaults immunological tolerance, leading to fetal rejection. Similar to T cells, NK cells can be categorized based on the characteristics of cytokines they secrete. Decidual NK (dNK) cells of RPL patients exhibited an increased NK1/NK2 ratio (IFN-γ/IL-4 producing NK cell ratios), leading to pro-inflammatory cytokine milieu and increased NK cell cytotoxicity. Genetic polymorphism may be the underlying etiologies for Th1 and Th17 propensity since it alters cytokine production. In addition, various hormones participate in cytokine regulations, including progesterone and estrogen, controlling cytokine balance in favor of the Th2 type. Consequently, the intricate regulation of cytokines and hormones may prevent the RPL of immune etiologies. Local or systemic administration of cytokines or their antagonists might help maintain adequate cytokine milieu, favoring Th2 over Th1 response or Treg over Th17 immune response in women with RPL. Herein, we provided an updated comprehensive review regarding the immune-regulatory role of pro- and anti-inflammatory cytokines in RPL. Understanding the roles of cytokines involved in RPL might significantly advance the early diagnosis, monitoring, and treatment of RPL.

Molecular investigation of association between common IL-6 polymorphism with cytomegalovirus (CMV) infection and recurrent miscarriage in Iranian women

BACKGROUND

Recurrent pregnancy loss (RPL) is described as two or more spontaneous abortions. To date, scientists in various fields of knowledge, such as genetics, endocrinology, anatomy, immunology, and microbiology, have identified some important factors that affect abortions; nonetheless, the precise basic etiology is not determined in up to 50% of RPL cases. Human cytomegalovirus (CMV) infection and host genetic background, like IL-6 SNP polymorphisms, play important roles in RPL etiology.

OBJECTIVE

This study aimed to evaluate the relationships among single nucleotide polymorphisms (-634C/G and -174 G/C) in the IL-6 gene with CMV infection and the risk of RPL for early detection and treatment.

MATERIALS AND METHODS

This case-control study was carried on 80 Iranian females with RPL and 80 healthy females as controls. DNA was extracted from samples and CMV and IL6 SNPs were detected using Tetra ARMS-PCR. Statistics were analyzed by Epi Info TM and SPSS software by X2 test for the roles of CMV detection and two polymorphisms in RPL.

RESULTS

The results indicated an increased rate of CMV infection in the RPL group (44%) compared to the control group (25.45%). The prevalence of IL-6-634C/G genotype among RPL patients with CMV infection was 80%, while the frequency of this genotype among RPL patients without CMV infection was 50%. Furthermore, no substantial relation was found between IL-6-174 G/C genotypes and RPL (p = 0.005).

CONCLUSION

This study not only indicated a significant role for CMV in RPL, but also showed an association between CMV and allele G in IL6-634 among Iranian women. In addition, the findings suggested the use of CMV and IL-6-634 GG genotypes as diagnostic and prognostic biomarkers for RPL in the Iranian population.

Effect of human follicle-stimulating hormone on immunomodulatory function of decidual mesenchymal stem cells by reducing interleukin-6 levels

Objective

Women with an elevated basal FSH indicate diminished ovarian reserve and reduced oocyte and embryo numbers. DMSCs are likely to be involved in immune tolerance of pregnancy maintenance. We investigate the effect of follicle-stimulating hormones on the immunomodulatory functions of DMSCs.

Methods

DMSCs were primary cultured from decidual tissue. Pretreated DMSCs with mitomycin C, combined with CD4⁺ T lymphocytes, DMSCs + CD4⁺T co-culture system was established. Different physiological dose FSH (3 ng/ml,10 ng/ml,30 ng/ml,100 ng/ml) were used to co-culture system. Cytokines (IFN-γ, IL-2, IL-4, IL-6, IL-10, TNF-α) and other proteins (FSHR, MyD88) were measured.

Results

Compared with the control group (FSH (0 ng/mL) + CD4⁺T + DMSCs), the FSH concentration was 10, 30, and 100 ng/ml, IL-6 levels were significantly reduced (P < 0.05). IL-6, MyD88 protein expression was remarkably decreased (P < 0.05).

Conclusion

FSH/FSHR could negatively regulate the immunosuppressive function of DMSCs by reducing secretion of IL-6 levels through MyD88 pathways, but upstream and downstream signalling pathways require further validation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-022-00993-3.

Cumulative Evidence for Association of IL-10 -1082G > A Polymorphism with Susceptibility to Recurrent Pregnancy Loss: A Systematic Review and Meta-Analysis

The IL-10 -1082 G > A polymorphism has been reported to be associated with a risk of recurrent pregnancy loss (RPL) with inconsistent results. Thus, to clarify the effect of the polymorphism on the susceptibility to RPL, a meta-analysis was performed. Methods: A systematic literature search in PubMed, Web of Science, Scopus and SciELO was performed to identify the relevant studies published up to December 20, 2019, and related information was extracted. Results: A total of 17 case-control studies with 3,224 RPL cases and 3,295 controls were selected. Pooled data revealed that IL-10 -1082 G > A polymorphism was significantly associated with risk of RPL in the global population. Moreover, subgroup analysis indicated a significant association in Caucasians, but not in Asian or mixed populations. Conclusions: Our pooled data highlights that IL-10 -1082 G > A polymorphism is a risk factor for RPL susceptibility in the global population, especially in Caucasians.

Association of raised serum progesterone and gene polymorphisms with risk of failure pregnancy and miscarriage

Balanced cytokine required for a healthy pregnancy to avoid miscarriage. There is yet no accord on the effect of raised progesterone on the endometrium, recurrent miscarriage and association with cytokines. The present study see the effect of raised serum progesterone level on ovulation, miscarriage, and association of selected Cytokines polymorphisms with recurrent miscarriage. In a controlled prospective study patients undergoing COS under controlled ovarian hyper stimulation were evaluated. On the day of trigger progesterone levels were measured and serum hormonal estimation assay was done on the day of ovulation trigger by automated immunoassay. Genotyping analysis using allelic discrimination method was conducted which detects SNPs base pair differences by comparing allele-specific fluorescence signal. There was no significant different between cases and controls in age, smoking habit and alcohol consumption habit. The ovulation trigger yielded >6 oocytes retrieval in majority of the patients. The mean stromal day were found to be statistically significant whereas the mean day of glands were insignificant. There is no significant difference observed between two groups for three studied polymorphisms. None of the polymorphisms deviated significantly from the Hardy Weinberg equilibrium, suggesting that the distribution in our subjects was representative of the actual population. The level of cytokines is guarded by various parameters, which are essential for a successful pregnancy. It is very complicated to predict the effect on endometrium and corresponding pregnancy rates due to increased progesterone.

Genetics of recurrent pregnancy loss among Iranian population

Background

Recurrent pregnancy loss (RPL) is one of the most common reproductive disorders which is defined as the occurrence of recurrent miscarriage before 24 weeks of gestation and is observed among 1%–5% of women.

Methods

Various factors are associated with RPL such as immunological disorders, maternal age, obesity, alcohol, chromosomal abnormality, endocrine disorders, and uterine abnormalities. About half of the RPL cases are related with chromosomal abnormalities. Therefore, RPL genetic tests are mainly limited to karyotyping. However, there is a significant proportion of RPL cases without any chromosomal abnormalities that can be related to the single‐gene aberrations. Therefore, it is required to prepare a diagnostic panel of genetic markers besides karyotyping.

Results

In the present review, we have summarized all the significant reported genes until now which are associated with RPL among Iranian women. We categorized all the reported genes based on their cellular and molecular functions in order to determine the molecular bases of RPL in this population.

Conclusion

This review paves the way of introducing a population‐based diagnostic panel of genetic markers for the first time among Iranian RPL cases. Moreover, this review clarifies the genetic and molecular bases of RPL in this population.

Association of IL-10, IL-18, and IL-33 genetic polymorphisms with recurrent pregnancy loss risk in Iranian women

Recurrent pregnancy loss (RPL) is a heterogeneous disease with three or more consecutive abortions before 20 weeks of pregnancy. Recently, inflammatory factors such as interleukins (IL) have been found to be a significant factor in the RPL. The objective of this study was to investigate the association between RPL and IL-10 (rs1800896), IL-18 (rs1946518) and IL-33 (rs1929992) genes polymorphisms in Iranian women. The study participants consisted of 300 women with RPL and the control group comprised of 300 healthy women with successful delivery. Genomic DNA was extracted from peripheral blood, and genotyping was performed by polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP). There were no significant differences in the frequencies of genotype and allele in IL-10 gene polymorphism (rs1800896) between patients and control group (p > .005). In contrast, there were significant differences in the frequencies of CC genotype in IL-18 gene polymorphism (rs1946518) between patients and the control groups (p = .004; OR =0.990; 95% CI: 0.320-8.855). Also, there were significant differences in the frequencies of GA genotype in IL-33 gene polymorphism (rs1929992) between patients and the control groups (p = .001; OR =0.955; 95% CI: 0.239-9.807). Present study showed that the rs1800896 polymorphism (IL-10) might not play role in RPL in the Iranian population; whereas rs1946518 (IL-18) and rs1929992 (IL-33) polymorphisms may be associated with the risk of RPL in the Iranian women.

Tumour necrosis factor alpha gene polymorphisms in women with recurrent pregnancy loss: a meta-analysis

Tumour necrosis factor alpha (TNF-α) concentration is associated with recurrent pregnancy loss (RPL). Moreover, TNF-α promoter polymorphisms affect cellular TNF-α concentrations. Although several studies on TNF-α polymorphisms have been reported, these studies only define specific loci and result in conflicting conclusions. The meta-analysis in this study was performed to examine the relationship between various TNF-α polymorphisms and RPL. We searched for articles, using MEDLINE and Embase, and performed meta-analysis of 21 studies involving 3437 cases and 4016 controls. The results demonstrated that the -308G/A polymorphism is positively associated with RPL, particularly in cases involving three or more miscarriages. For -1031T/C, -863C/A, and -376G/A polymorphisms, recessive and homozygote models revealed significant associations with RPL. However, -857C/T, -238G/A, and +488G/A polymorphisms showed no association with RPL. A subgroup analysis with respect to ethnicity demonstrated that the -308G/A and -238G/A polymorphisms are associated with RPL in Asian and Middle Eastern populations, respectively. This meta-analysis showed the associations between TNF-α polymorphisms and RPL. However, further studies of genetic polymorphisms in TNF-α other than -308G/A and -238G/A are required.

Association of Tumor Necrosis Factor-α (TNF-α) -308G>A and -238G>A Polymorphisms with Recurrent Pregnancy Loss Risk: A Meta-Analysis

Background

Multiple studies have been carried out examining the association of tumor necrosis factor-α gene (TNF-α) promoter region polymorphisms with recurrent pregnancy loss (RPL) risk. However, the results remain controversial and incomplete. Hence, we performed a meta-analysis to evaluate the association of the TNF-α -308G>A and -238G>A polymorphisms with RPL risk.

Materials and Methods

In this meta-analysis, a comprehensive search of PubMed, Web of Knowledge and EMBASE was performed to identify relevant studies published until December 1, 2017. The associations were assessed by odds ratio (OR) and its corresponding 95% confidence interval (CI).

Results

A total of 29 case-control studies, comprising 20 studies on TNF-α -308G>A (3,461 cases and 3,895 controls) and nine studies on TNF-α -238G>A (2,589 cases and 2,664 controls), were included in the meta-analysis. Overall, we found TNF-α -308G>A to be associated with an increase in RPL risk under the homozygote (OR=1.716, 95% CI: 1.210-2.433, P=0.002) and the recessive (OR=1.554, 95% CI: 1.100-2.196, P=0.012) models. TNF-α -238G>A was also significantly associated with increased risk of RPL under the allele model (OR=1.554, 95% CI: 1.100-2.196, P=0.012). Stratified analysis revealed a more significant association between theTNF-α -308G>A polymorphism and increased RPL risk in Asians under the homozygote (OR=2.190, 95% CI: 1.465-3.274, P≤0.001), the dominant (OR=1.642, 95% CI: 1.269-2.125, P≤0.001) and the recessive (OR=1.456, 95% CI: 1.039-2.040, P=0.029) models, but not in Caucasians. A non-significant association was, however, identified between TNF-α -238G>A and RPL risk based on ethnicity. Moreover, TNF-α -308G>A and -238G>A polymorphisms were significantly associated with increased risk of RPL in high quality studies and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) subgroups.

Conclusion

The present meta-analysis demonstrates that TNF-α -308G>A and -238G>A polymorphisms are associated with an increased risk of RPL.

Haplotype analysis of IL-10 gene polymorphism in couples with spontaneous abortions and aborted fetuses

Spontaneous abortion is the loss of pregnancy during an early gestational period. Interleukin-10 is an anti-inflammatory cytokine which plays an important role in successful pregnancy outcome. The aim of the study is to elucidate an association of IL-10 gene promoter polymorphisms (-1082G/A, -819 C/T, -592C/A) in spontaneous abortions from Telangana state of South India. The present population-based retrospective case-control triad study includes a total of 80 case families with spontaneous abortions and 100 control families with medically terminated pregnancies. Peripheral blood from all the couples and fetal tissues of <20 weeks of gestation were collected. Genotype analysis was carried out by a standard amplification refractory mutation system-polymerase chain reaction followed by agarose gel electrophoresis. The strength of the association between IL-10 gene promoter polymorphisms and spontaneous abortions were measured by odd ratios and their respective 95% confidence intervals. Haplotype analysis was carried out for the three polymorphisms to establish an association of specific haplotypes with spontaneous abortions. The increased frequency of AA genotype and A allele of -1082G/A, TT genotype and T allele of -819C/T, and AA genotype and A allele of -592C/A was observed in case fetuses and case mothers compared to their respective controls. Haplotype analysis revealed that A-C-A, G-C-A haplotypes in fetuses and haplotypes A-C-C, G-T-C, A-T-A, and G-C-A in mothers were associated with increased risk of spontaneous abortions. IL-10 gene promoter polymorphisms may act as a major genetic regulator in the etiology of spontaneous abortions with maternal genome imprinting effects.

Genotyping of IL-4 -590 (C>T) Gene in Iraqi Asthma Patients

This study is the first investigation in Iraq dealing with genotyping of IL-4 −590 (C>T) gene, especially in Iraqi patients with asthma. We studied forty-eight blood samples collected from patients with asthma and compared with age-matched 25 healthy individuals as controls. The polymorphism results of IL-4 −590 (C>T) gene by using amplification refractory mutation system (ARMS-PCR) showed the presence of C and T alleles and three genotypes (CC, CT, and TT). Interestingly the frequency of C allele and CC genotype was higher in patients with asthma in comparison with the same allele and genotype in control (P 1 × 10⁻⁶). This increase was associated with an increased risk factor of asthma (odds ratio [OR] 9.21; 95% confidence interval [CI] 3.58–23.71). Genotypes analysis by using Hardy-Weinberg distribution showed no significant differences between patients with asthma and healthy subjects. In conclusion, the increasing risk of asthma was associated with C allele and the CC genotype and these are revealed as etiological fraction with risk by having this disease, while the T allele percentage ratio in controls was higher when it is compared with asthma patients suggesting that these alleles have a protective effect (preventive fraction).

Association between Genetic Polymorphisms in Interleukin Genes and Recurrent Pregnancy Loss - A Systematic Review and Meta-Analysis

Interleukins are a group of immunomodulatory proteins that mediate a variety of immune reactions in the human body. To investigate the association between interleukin gene polymorphisms and recurrent pregnancy loss (RPL), we reviewed 21 studies from MEDLINE, EMBASE, OVID SP and PubMed to evaluate RPL-related interleukin gene polymorphisms. Meta-analysis was performed on 12 of the polymorphisms, and a review included the others. Our integrated results indicated that IL-1β (-511C/T) (P = 0.02, 95% CI 0.77[0.62,0.96]), IL-6 (-634C/G) (P<0.001, 95% CI 2.91[2.01,4.22]), IL-10 (-1082G/A, -819T/C) (P = 0.01, 95% CI 0.80[0.67,0.96]; P<0.01, 95% CI 0.66[0.49,0.89]), and IL-18 (-137G/C, -105G/A) (P<0.01, 95% CI 1.69[1.24,2.31]; P = <0.01, 95% CI 1.41[1.17,1.70]) consistently associated with RPL after meta-analysis. IL-17A rs2275913 and IL-17F rs763780, IL-21 rs2055979 and rs13143866, IL-1β (-31C/T), IL-6 (-2954G/C), and IL-10 (-536A/G) were reported only once as having a significant association with RPL. The potential mechanism underlying miscarriage and these polymorphisms and future research directions are also discussed.

No Association between TNF-α -308G/A Polymorphism and Idiopathic Recurrent Miscarriage: A Systematic Review with Meta-Analysis and Trial Sequential Analysis

Background

Conflicting results were reported on the association between the TNF-α -308G/A polymorphism and idiopathic recurrent miscarriage (IRM). Though three meta-analyses have been conducted on this topic, the conclusions were contradictory, and the results may be unreliable as certain crucial conditions were neglected.

Method

A complete search was conducted in PubMed, Cochrane Library, and Embase, other sources like Google Scholar, ClinicalTrial.gov and reference lists of relevant articles were also retrieved. All candidate articles were accessed and screened using specific inclusion and exclusion criteria. Statistical analyses were performed on data extracted from eligible studies using the STATA 12.0 software and the TSA 0.9 beta software.

Results

Eventually, 12 case-control studies from 11 publications (with 1,807 cases and 2,012 controls) were included in this meta-analysis, and no evidence of any significant association was found in the overall analyses between the TNF-α -308G/A polymorphism and IRM risk. However, significant association was shown in Asian population (four studies from three publications) in the dominant model (AA + GA vs. GG), the allelic model (A vs. G), and the heterozygote model (GA vs. GG).

Conclusions

TNF-α -308G/A polymorphism is not associated with IRM risk. Though significant association was found in Asian population, the result needs further confirmation from more studies.

Association of tumor necrosis factor-alpha 308G/A polymorphism with recurrent miscarriages in women

BACKGROUND

Recurrent miscarriage (RM) is the most common pregnancy loss in the first trimester affecting approximately 0.5-2% of women. It is a heterogeneous condition and remains an enigma as the underlying cause is still difficult to track down.

AIM

This study was aimed to investigate the distribution of tumor necrosis factor-alpha (TNF-α) 308G/A polymorphism and its association with RM in females. The comparative picture was also demonstrated by comparing genotyping results with healthy control women having no history of miscarriage.

METHODS

This clinical study was conducted among 115 women aged 21-44 years with history of recurrence of miscarriage. The samples were collected from women attending the outpatient departments of various hospitals, nursing homes, and infertility clinics of this region. In the present study, 111 fertile healthy women aged 24-46 years with at least one live birth and no history of miscarriage were also included.

RESULTS

Mean age of women with RM was found to be 28 ± 5.6 years by recall method, whereas it was found to be 30 ± 7.4 in context to healthy women with no history of pregnancy loss. In the present study, 66% of women with RM had homozygous wild type genotype (GG) while 30% and 4% of women had heterozygous (GA) and homozygous mutant genotype (AA), respectively. Among control group, 79%, 16%, and 5% of women showed GG, GA, and AA genotype, respectively.

CONCLUSION

The current study supports the concept of TNF-α 308G/A variant in particular with reproductive failure, GG and GA alleles showing 1-fold risk association with RM (odds ratio: 1.86 and 1.43, respectively).

Immunogenetic contributions to recurrent pregnancy loss

While sporadic pregnancy loss is common, occurring in 15 % of pregnancies, recurrent pregnancy loss (RPL) impacts approximately 5 % of couples. Though multiple causes are known (including structural, hormonal, infectious, autoimmune, and thrombophilic causes), after evaluation, roughly half of all cases remain unexplained. The idiopathic RPL cases pose a challenging therapeutic dilemma in addition to incurring much physical and emotional morbidity. Immunogenetic causes have been postulated to contribute to these cases of RPL. Natural Killer cell, T cell expression pattern changes in the endometrium have both been shown in patients with RPL. Human leukocyte antigen (HLA) and cytokine allelic variations have also been studied as etiologies for RPL. Some of the results have been promising, however the studies are small and have not yet put forth outcomes that would change our current diagnosis and management of RPL. Larger database studies are needed with stricter control criteria before reasonable conclusions can be drawn.

Association of interleukin-10 gene promoter polymorphisms with recurrent pregnancy loss: a meta-analysis

PURPOSE

It has been reported single-nucleotide polymorphisms (SNPs) of the IL-10 promoter might be associated with the susceptibility to recurrent pregnancy loss (RPL). Owing to the inconclusive results, we conducted a meta-analysis to systematically summarize and clarify the association between the IL-10 promoter SNPs and RPL risk.

METHODS

A systematic search of studies on the association of the three SNPs with RPL was conducted in PubMed and Embase. Odds ratios (ORs) and 95 % confidence intervals (95 % CIs) were used to pool the effect size.

RESULT

Eleven case-control studies on rs1800896, seven studies on rs1800871, and eight studies on rs1800872 were included. A significant association was identified between IL-10 rs1800896 with RPL risk (G versus A: OR = 1.21, 95 % CI 1.09-1.35). No evidence of association was found between rs1800871 and RPL when restricted to those studies in Hardy-Weinberg equilibrium in controls (T versus C: OR = 1.25, 95 % CI 0.76-2.06). No statistical association was demonstrated between rs1800872 and RPL (C versus A: OR = 1.08, 95 % CI 0.83-1.42).

CONCLUSIONS

IL-10 rs1800896 significantly increases the risk of RPL, while rs1800872 is not correlated with RPL risk. No significant association is demonstrated between rs1800871 and RPL risk but this requires further investigation.

Association of TNF-α genetic polymorphisms with recurrent pregnancy loss risk: a systematic review and meta-analysis

BACKGROUND

Several studies on the association of tumor necrosis factor alpha (TNF-α) polymorphisms with recurrent pregnancy loss (RPL) risk have reported conflicting results. The present meta-analysis was conducted to provide a more precise estimation of these relationships and to investigate the real association between TNF-α polymorphisms and RPL.

METHODS

An extensive eligible literature search for relevant studies was conducted on PubMed, Embase, and The Cochrane Library from their inceptions to May 12, 2015. Specific inclusion criteria were used to evaluate articles. The odds ratio (OR) with 95% confidence intervals (CIs) were used to assess the strength of associations. Statistical analyses were performed by the STATA12.0 software.

RESULTS

10 case-control studies including 1430 RPL patients and 1727 healthy controls were identified. Meta-analysis indicated that TNF-α-308G/A (rs1800629) polymorphism in the TNF-α gene correlated with elevated RPL risk whereas no significant association was observed between TNF-α-238G/A (rs361625) and RPL.

CONCLUSIONS

The current meta-analysis demonstrates that TNF-α-308G/A polymorphism in the TNF-α gene is associated with susceptibility to RPL.

Association between IL-6 -174 G/C, IL-6 -634 G/C, and IFN-γ +874 A/T polymorphisms and susceptibility to recurrent pregnancy loss: a meta-analysis

OBJECTIVE

The aim of this study was to determine whether interleukin-6 (IL-6) -174 G/C, IL-6 -634 G/C, and interferon-γ (IFN-γ) +874 A/T polymorphisms are associated with susceptibility to recurrent pregnancy loss (RPL).

METHODS

We conducted a literature search using PubMed and EMBASE databases and performed a meta-analysis using fixed- or random-effects models.

RESULTS

A total of 15 articles met the study inclusion criteria. When all study subjects were considered together, meta-analysis showed no association between RPL and the IL-6 -174 GG + GC genotype (odds ratio [OR] = 0.794, 95 % confidence interval [CI] = 0.542-1.163, p = 0.236). However, stratification of the data by ethnicity indicated an association between this genotype and RPL in non-Caucasians (OR = 0.528, 95 % CI = 0.302-0.925, p = 0.028), but not in Caucasian populations. Moreover, meta-analysis revealed an association between RPL and the IL-6 -634 GG + GC genotype in all study subjects (OR = 0.556, 95 % CI = 0.383-0.806, p = 0.002), while stratification by ethnicity revealed a negative association between this genotype and RPL in Asian (OR = 0.545, 95 % CI = 0.371-0.800, p = 0.002) but not Middle Eastern populations. Furthermore, a relationship between the IFN-γ +874 A allele and RPL was identified in non-Caucasians (OR = 1.403, 95 % CI = 1.133-1.734, p = 0.002), but not in Caucasians.

CONCLUSIONS

This meta-analysis demonstrates that IL-6 -174 G/C, IL-6 -634 G/C, and IFN-γ +874 A/T polymorphisms are associated with susceptibility to RPL, particularly in non-Caucasians.

A functional polymorphism in the promoter region of interleukin-10 gene increases the risk for spontaneous abortions--a triad study

PURPOSE

Spontaneous abortion or miscarriage is the natural death of an embryo or foetus in the early stages of prenatal development. Interleukin-10 is an anti-inflammatory cytokine, produced by human cytotrophoblasts, and defects in its production result in specific pathological conditions during pregnancy. The present study is aimed to evaluate the association of IL-10 -1082G/A polymorphism in spontaneous abortions by comparing foetal, maternal and paternal groups--a triad study.

METHODS

A total of 50 families with spontaneous abortions and 60 families with medically terminated pregnancies were considered for the present study. DNA from foetal tissue and parental blood samples were extracted, and the genotype analysis of IL-10 -1082G/A promoter polymorphism was carried out by amplification refractory mutation system-polymerase chain reaction followed by agarose gel electrophoresis. A statistical analysis was applied to test for the significance of the results.

RESULTS

There was a statistically significant difference in the distribution of AA genotypes and A allele of IL-10 -1082G/A between the two family groups among foetuses (P = 0.0002) and mothers (P = 0.00005). The paternal group showed no significant difference in the genotype distribution of IL-10 between cases and controls.

CONCLUSION

In conclusion, IL-10 G-1082A gene promoter polymorphism may act as a major genetic regulator in the etiology of spontaneous abortions.

The Impact of IFN-γ Gene Polymorphisms on Spontaneous Clearance of HCV Infection in Fars Province, Southern of Iran

BACKGROUND

Certain polymorphisms in cytokine genes such as IFN-γ may influence the outcome of hepatitis C virus (HCV) infection. Here the frequency of the genotype, allele, and haplotype of IFN-γ gene at some loci is investigated in HCV-infected patients.

METHODS

Totally 255 patients with chronic HCV infection and 44 spontaneously cleared individuals were included. The chronic or clearance states were confirmed using enzyme-linked immunosorbent assay (ELISA) and two different qualitative reverse transcriptase polymerase chain reaction (RT-PCR) techniques. IFN-γ gene polymorphisms were performed by PCR using sequence-specific primers and PCR-RLFP on extracted genomic DNA.

RESULTS

The frequency of GG genotype (P = 0.0001, OR: 5.69 and CI: 2.21-14.62) and allele (P = 0.0003, OR: 2.73 and CI: 1.54-4.83) of IFN-γ gene at +2109 locus was significantly higher in cases that spontaneously cleared the infection. Haplotype analysis showed the association of AG haplotype (P = 0.0046, OR = 6.14 and CI = 1.56-25) with spontaneous clearance of the infection.

CONCLUSION

Our finding indicated that individuals with GG genotype at +2109 loci of IFN-γ gene and also AG haplotype (A allele at +874 loci and G allele at +2109 loci) may clear HCV infection more frequently than those with AA and AG genotype at +2109 loci and AA, TA, and TG haplotype.

Associations between Individual and Combined Polymorphisms of the TNF and VEGF Genes and the Embryo Implantation Rate in Patients Undergoing In Vitro Fertilization (IVF) Programs

BACKGROUND

A multiple pregnancy is now considered to be the most common adverse outcome associated with in vitro fertilization (IVF). As a consequence, the identification of women with the best chances of embryo implantation is a challenge in IVF program, in which the objective is to offer elective single-embryo transfer (eSET) without decreasing the pregnancy rate. To date, a range of hormonal and clinical parameters have been used to optimize eSET but none have significant predictive value. This variability could be due to genetic predispositions related to single-nucleotide polymorphisms (SNPs). Here, we assessed the individual and combined impacts of thirteen SNPs that reportedly influence the outcome of in vitro fertilisation (IVF) on the embryo implantation rate for patients undergoing intracytoplasmic sperm injection program (ICSI).

MATERIALS AND METHODS

A 13 gene polymorphisms: FSHR(Asn680Ser), p53(Arg72Pro), AMH(Ile49Ser), ESR2(+1730G>A), ESR1(-397T>C), BMP15(-9C>G), MTHFR1(677C>T), MTHFR2(1298A>C), HLA-G(-725C>G), VEGF(+405G>C), TNFα(-308A>G), AMHR(-482A>G), PAI-1(4G/5G), multiplex PCR assay was designed to genotype women undergoing ICSI program. We analyzed the total patients population (n = 428) and a subgroup with homogeneous characteristics (n = 112).

RESULTS

Only the VEGF(+405G>C) and TNFα(-308A>G) polymorphisms impacted fertilization, embryo implantation and pregnancy rates. Moreover, the combined VEGF+405.GG and TNFα-308.AG or AA genotype occurred significantly more frequently in women with high implantation potential. In contrast, the VEGF+405.CC and TNFα-308.GG combination was associated with a low implantation rate.

CONCLUSION

We identified associations between VEGF(+405G>C) and TNFα(-308A>G) polymorphisms (when considered singly or as combinations) and the embryo implantation rate. These associations may be predictive of embryo implantation and could help to define populations in which elective single-embryo transfer should be recommended (or, conversely, ruled out). However, the mechanism underlying the function of these polymorphisms in embryo implantation remains to be determined and the associations observed here must be confirmed in a larger, more heterogeneous cohort.

IL-10 gene promoter and intron polymorphisms and changes in IL-10 secretion in women with idiopathic recurrent miscarriage

STUDY QUESTION

Is recurrent pregnancy loss (RPL) associated with polymorphisms in the promoter and intron regions of the interleukin-10 (IL-10) gene?

SUMMARY ANSWER

IL-10 rs1518111 was found to be associated with RPL but the commonly studied promoter variants rs1800872, rs1800871 and 1800896 were not.

WHAT IS KNOWN ALREADY

Reduced expression of IL-10 is implicated in RPL, due to defective maternal immune tolerance (causing early miscarriages) or placental vascular insufficiency (causing late losses). IL-10 production is in part inherited, and IL-10 gene variants associated with reduced IL-10 expression have been analyzed for their association with RPL, often with inconclusive results.

STUDY DESIGN, SIZE, DURATION

A retrospective case-control study was performed between January 2011 and April 2012. The subjects comprised 296 RPL cases and 305 control women.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Genotyping of the IL-10 intron (rs1878672, rs3024492, rs1554286, rs1518111, rs3024491, rs3024490) and promoter (rs1800872, rs1800871, rs1800896) variants was done by real-time PCR, with defined clusters.

MAIN RESULTS AND THE ROLE OF CHANCE

A higher minor allele frequency (MAF) of rs1518111 (P = 0.03) was in seen RPL cases; but the MAFs of the remaining SNPs were comparable between cases and controls. Setting the homozygous major allele genotype (1/1) as the reference, significantly higher frequencies of heterozygous rs1554286 and rs1800872, and homozygous rs1800896 genotype carriers, and a reduced frequency of homozygous rs1518111 genotype carriers, were seen in RPL cases, while the distribution of the remaining genotypes were comparable between cases and controls. Serum IL-10 levels were significantly reduced in RPL cases compared with control women (P = 0.002), and this correlated with rs1518111 and rs1800871 genotypes in both groups, and with the rs1800872 genotype among control women. A nine-locus (rs1878672, rs3024492, rs1554286, rs1518111, rs3024491, rs3024490, rs1800872, rs1800871 and rs1800896) haploview analysis demonstrated an increased frequency of haplotype 112112121 in RPL cases, thus conferring a disease susceptibility nature to this haplotype.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of this study was that it was limited to Bahraini Arabs, thereby necessitating parallel studies of other ethnic groups. Another limitation is the study design, which prompts speculation on whether it is a cause-effect relationship.

WIDER IMPLICATIONS OF THE FINDINGS

While the lack of association of the various IL-10 promoter variants with RPL was in agreement with reports from varied ethnic groups, this is the first study to confirm the association between IL-10 rs151811 intronic variant and RPL.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by grants from the Arabian Gulf University Research Fund. None of the authors report any competing interests.

The Role of Interferon Gamma Gene Polymorphism (+874A/T, +2109A/G, and -183G/T) in Response to Treatment Among Hepatitis C Infected Patients in Fars Province, Southern Iran

BACKGROUND

Hepatitis C virus (HCV) infection as a worldwide health problem is associated with cirrhosis and hepatocellular carcinoma. With current treatment regimen, pegylated interferon (PEG-IFN) plus ribavirin, sustain virological response (SVR) is achieved in only 50% of infected individuals. In HCV infection, an inappropriate ratio of cytokines may affect the benefit of antiviral therapy. Given the polymorphisms in regulatory regions of cytokines genes may influence cytokines production.

OBJECTIVES

We aimed to investigate both the frequency of genotypes and alleles of interferon gamma (IFN-γ) gene at +874A/T, +2109A/G, and -183G/T loci in HCV-infected patients and their associations with response to therapy.

PATIENTS AND METHODS

A total of 158 patients were included and treated with PEG-IFN plus ribavirin. The presence of HCV infection in patients was confirmed by reverse transcription polymerase chain reaction, and genomic DNA was extracted from peripheral leukocytes using salting out method. IFN-γ gene polymorphisms were identified by polymerase chain reaction using sequence specific primers and restriction fragment length polymorphism analysis on genomic DNA.

RESULTS

Of 158 patients, 110 (69.5%) subjects achieved SVR and 48 (30.5%) subjects did not respond to therapy. The frequency of AA genotype (P = 0.001; OR: 11.2; CI: 2.26-63.21) and A allele (P = 0.01; OR: 3.23; CI: 1.23 8.56) of IFN-γ gene at +2109 locus were significantly different between the responder and non-responder subjects infected with genotype 1. Regardless of HCV genotype, the frequency of AG genotype was also higher in responder group than those who did not respond to therapy (P = 0.041; OR: 05.05; CI: 1.05-33.25)). In case of IFN-γ gene at +874 locus, there was no difference in genotypes and alleles frequencies between the responder and non-responder subjects infected with HCV genotypes 1 and 3. Haplotype analysis showed no association between haplotypes and response to therapy. All participants had G/T genotype at -183 locus.

CONCLUSIONS

Our findings indicate that heterogeneity at +2109 locus of IFN-γ gene but not at +874 locus could interfere with successful therapy in patients infected with HCV genotype 1.

Tumor necrosis factor-α gene polymorphisms in Korean patients with recurrent spontaneous abortion

The objective of this study was to investigate the contribution of the tumor necrosis factor-α (TNF-α) gene polymorphisms to recurrent spontaneous abortion (RSA). The study participants consisted of 357 Korean women with RSA and 236 fertile women controls. Four TNF-α gene variants of all participants were analyzed by polymerase chain reaction-restriction fragment length polymorphism assay. The TNF-α -1031T>C and TNF-α -238G>A variants increased the risk of RSA TNF-α -1031TC+CC; adjusted odds ratio [AOR], 2.292; 95% confidence interval [CI], 1.547-3.395; P < .001; TNF-α -238GA+AA; AOR, 2.327; 95% CI, 1.038-5.217; P = .040), and these data were not different in a stratified analysis according to the number of consecutive spontaneous abortions. Also, the mutant genotypes of TNF-α -1031 and TNF-α -238 showed synergistic effects on increased RSA risk (-1031TC+CC/-238GA+AA; AOR, 4.054; 95% CI, 1.520-10.812; P = .005). In haplotype analysis, there were similar trends of data for combination analysis. In conclusion, the TNF-α -1031T>C and TNF-α -238G>A variants are possible genetic risk factors for RSA.

Genetics of recurrent miscarriage: challenges, current knowledge, future directions

Recurrent miscarriage (RM) occurs in 1-3% of couples aiming at childbirth. Due to multifactorial etiology the clinical diagnosis of RM varies. The design of genetic/"omics" studies to identify genes and biological mechanisms involved in pathogenesis of RM has challenges as there are several options in defining the study subjects (female patient and/or couple with miscarriages, fetus/placenta) and controls. An ideal study would attempt a trio-design focusing on both partners as well as pregnancies of the couple. Application of genetic association studies focusing on pre-selected candidate genes with potential pathological effect in RM show limitations. Polymorphisms in ∼100 genes have been investigated and association with RM is often inconclusive or negative. Also, implication of prognostic molecular diagnostic tests in clinical practice exhibits uncertainties. Future directions in investigating biomolecular risk factors for RM rely on integrating alternative approaches (SNPs, copy number variations, gene/protein expression, epigenetic regulation) in studies of single genes as well as whole-genome analysis. This would be enhanced by collaborative network between research centers and RM clinics.

Association of tumor necrosis factor-α gene promoter polymorphisms (-308G/A, -238G/A) with recurrent spontaneous abortion: a meta-analysis

Tumor necrosis factor-α (TNF-α) gene promoter polymorphisms (-308G/A, -238G/A) have been associated with increased recurrent spontaneous abortion (RSA) risk, but the results of published articles are controversial. Hence, a meta-analysis was performed to assess the effect of TNF-α -308G/A, -238G/A polymorphisms on RSA risk. Heterogeneity testing and sensitivity analysis were performed using RevMan 5.0 software. Publication bias was assessed by the funnel plot method and modified Egger's linear regression test. In 12 studies for the TNF-α -308G/A polymorphism, the summary odds ratio (OR) with the corresponding 95% confidence interval (95% CI) was 1.04 (95% CI: 0.86, 1.26) under a fixed-effect model in the overall population. In 5 studies for the TNF-α -238G/A polymorphism, the summary OR with the corresponding 95% CI was 1.11 (95% CI: 0.60, 2.03) under a random-effect model in the overall population. We could not identify the sources of heterogeneity for TNF-α -238G/A. In addition, no evidence of publication bias was detected. The results of this meta-analysis indicate that TNF-α -308G/A, -238G/A polymorphisms are not significantly associated with the risk of RSA in the overall population. However, more convincing evidence is required to draw a solid conclusion on the relation between the TNF-α -238G/A polymorphism and the risk of RSA.

Recurrent pregnancy loss: TNF-α and IL-10 polymorphisms

BACKGROUND:

The recurrent pregnancy loss requires careful consideration of genetic, anatomic, endocrine, infectious and immunological factors. Cytokine gene polymorphisms in the promoter regions of tumor necrosis factor (TNF)-α and interleukin (IL)-10 are associated with recurrent pregnancy loss.

AIM:

The aim of present study was to investigate the association of the IL-10 -592C/A and TNF-α-308 G/A, promoter polymorphisms among women with at least three consecutive miscarriages.

MATERIALS AND METHODS:

Genotyping was done in 50 women with RPL for IL-10-592C/A and TNF-α-308G/A promoter polymorphism to see the association of these loci with pregnancy loss. The control group included 50 healthy women having two or more children (mean age of the female subjects 35 years) for statistical comparisons.

RESULTS:

IL- 10-592C/A and TNF-α-308G/A promoter polymorphisms were not associated with the recurrent miscarriages.

CONCLUSIONS:

There is a need to screen a larger sample and in different ethnic groups using IL-10-592C/A and TNF-α-308G/A markers to understand their association with recurrent miscarriages. This would further help in efficient management of immunologically mediated recurrent miscarriages at the sample/individual level.

Cytokine gene polymorphism and asthma susceptibility, progress and control level

Asthma is a multifactor inflammatory disorder, and its management requires understanding of its various pathogenesis and control mechanisms. Cytokines and other inflammatory mediators are important factors in asthma pathophysiology. In this study, we evaluated the role of cytokine polymorphisms in the asthma susceptibility, progress, control, and lung functions. IL-4-C590T polymorphism by PCR-RFLP method, IFN-γ T+874A, TNF-α-A308G, IL-6 G-174C and TGF-β T+869C variants by ARMS-PCR method and IgE serum level by ELISA technique were determined in 81 asthmatic patients and 124 normal subjects. Asthma diagnosis, treatment and control levels were considered using standard schemes and criteria. TNF-α-308GA genotype was more frequent in asthmatics (P = 0.025, OR 3.352), and polymorphisms between different asthma control levels (P > 0.05) were not different. IFN-γ+874AT genotype had a positive correlation with the familial history of asthma (P = 0.034, OR 2.688). IL-6-174C allele (P = 0.045), TNF-α-308GG genotype (P = 0.002) and TNF-α-308G allele (P = 0.004) showed reduced values, and TNF-α-308GA genotype (P = 0.002) increased FEF25-75 value in asthmatics. IFN-γ+874AA genotype caused a decrease in FVC factor (P = 0.045). This study showed that TNF-α-308GA is a risk factor for asthma, but cytokine gene variants do not affect asthma control and IgE serum levels. Variants producing lower levels of IL-6, TNF-α and IFN-γ are associated with reduced pulmonary capacities. To achieve an appropriate schema for asthma management, further studies with consideration of different aspects in a larger group of patients would be more elucidative.

Cytokines in recurrent pregnancy loss

BACKGROUND

Recurrent pregnancy loss (RPL) is defined as the occurrence of three or more consecutive miscarriages prior to 20 weeks gestation. Exaggerated maternal immune response to fetal antigens has been proposed to be one of the mechanisms underlying recurrent pregnancy loss.

METHOD

A comprehensive literature search was conducted from the websites of the National Library of Medicine (http://www.ncbl.nlm.nih.gov) and Pubmed Central, the US National Library of Medicine's digital archive of life sciences literature (http://www.pubmedcentral.nih.gov/). The data was assessed from books and journals that published relevant articles in this field.

RESULT

In normal pregnancy, tolerance of the genetically incompatible fetus by the maternal immune system depends on the interactions of an array of cytokines secreted by maternal and fetal cells at the site of implantation. Earlier research indicated that altered immunity in RPL is dominated by the Th1/Th2 hypothesis, which proposed that the fetus escapes maternal-derived T-cell responses through skewing the Th0 differentiation toward Th2 pathway which dampens pro-inflammatory Th1-type immunity. Recent studies indicate the role of proinflammatory Th17 cells and immunoregulatory Treg cells in RPL in addition to Th1/Th2 interactions.

CONCLUSION

Cytokines form a complex regulatory network which maintains homeostasis between the fetal unit and the maternal immune system. If this delicate balance is adversely affected, immunoregulatory mechanisms may be insufficient to restore homeostasis and this may lead to pregnancy failure.

Association of IL-6 promoter and IFN-γ gene polymorphisms with acute rejection of liver transplantation

Liver transplantation is one of the most important therapies for end-stage liver diseases and is associated with major problems including infections and acute rejection. The outcome of transplantation can be determined by immune responses as a key role in response to the graft. Inflammatory and anti-inflammatory mediators especially cytokines influence the graft microenvironment. Th1 and Th2 immune responses in contrast to regulatory responses cause acute rejection or help graft survival. In this study, we evaluated the gene polymorphisms of IL-6 G-174C, TGF-β T + 869C, IL-4 C-590T, and IFN-γ T + 874A cytokines in liver transplant patients. ARMS-PCR method was used to characterize IL-6 G-174C, TGF-β T + 869C and IFN-γ T + 874A polymorphisms and PCR-RFLP using AvaII restriction enzyme was done for IL-4 C-590T characterization in 70 liver transplant patients. Acute rejection episodes were diagnosed according to standard criteria. The analysis of the results showed that IL-6-174 GG genotype ( P = 0.009, OR = 4.333, 95% CI = 1.043-18.000), IL-6-174G allele (P = 0.011, OR = 5.273, 95% CI = 1.454-19.127) was more frequent and IFN-γ +874 TT genotype was less frequent (P = 0.043, OR = 0.143, 95% CI = 0.0118-1.190) in acute rejection than in non-rejection patients. TGF-β T + 869C and IL-4 C-590T frequencies were not significantly different (P > 0.05). According to the results, it can be conclude that IL-6 G-174C and IFN-γ T + 874A gene polymorphisms have predictive values for acute rejection after liver transplantation. High producer genotype of IL-6 is a genetic risk factor and IFN-γ is a protective factor for acute rejection development.

Association between genetic polymorphisms in cytokine genes and recurrent miscarriage--a meta-analysis

A meta-analysis of association studies was performed to assess whether the reported genetic polymorphisms in cytokine genes are risk factors for recurrent miscarriage (RM). The electronic PubMed database was searched for case-control studies on immunity-related genes in RM. Investigations of a single polymorphism/gene involvement in RM reported more than five times were selected. Aggregating data from seven case-control studies on -308/tumour necrosis factor-alpha polymorphism, the odds ratio (OR) for RM was 1.1 (0.87-1.39) if the polymorphism was considered under a dominant genetic model. In six studies on -1082/interleukin-10 (IL-10) polymorphism, the OR under a dominant model was 0.76 (0.58-0.99), and under a recessive model the OR was 0.90 (0.71-1.15). In five case-control studies on -174/IL-6 polymorphism, the OR for RM under a recessive model was 1.29 (0.69-2.40). The results show a statistically significant association with RM for the -1082/IL-10 genotype.

TNFA gene promoter polymorphisms and susceptibility to recurrent pregnancy loss in Italian women

The aim of this study was to investigate the relationship between serum tumor necrosis factor alpha (TNF-alpha) levels and single nucleotide polymorphisms (SNPs) of the TNFA gene promoter (-376G/A, -308G/A, and -238G/A) in 100 Italian Caucasian women with reproductive failure and 100 fertile controls. Molecular analysis of TNFA SNPs showed higher frequencies of -238G allele (P = .028) as well as the presence of a 3-loci haplotype (-376G/-308A/-238G; P = .020) in fertile controls compared to women with reproductive failure. Serum TNF-alpha levels were higher in study women compared to controls ( P = .001). Of interest, the TNFA -376G/-308A/-238G haplotype was an independent predictor of low TNF-alpha levels (P = .021) and miscarriage (P = .023) in multivariate analyses. In conclusion, these findings support the concept of an association of TNFA polymorphisms and recurrent pregnancy loss (RPL). In particular, the TNFA -238GG variant and the TNFA -376G/-308A/-238G haplotype might represent protective factors, probably through reduced TNF-alpha production and/or mediated responses.

Tumor necrosis factor-alpha polymorphisms in women with idiopathic recurrent miscarriage

We investigated the association of tumor necrosis factor-alpha (TNFalpha) gene polymorphisms with idiopathic recurrent miscarriage (RM). TNFalpha -1031T/C, -863C/A, -857C/T, -376G/A, -308G/A, -238G/A, and +488G/A single nucleotide polymorphisms (SNPs) were investigated in 204 RM women and 248 age-matched parous women by PCR-restriction fragment length polymorphism. Significantly higher frequencies of -1031C and -376A alleles were seen in RM patients; significant differences were also noted in the distribution of -1031T/C, -376G/A, and -238G/A genotypes between case and control subjects. Haploview analysis revealed high linkage disequilibrium between -857C/T and +488G/A SNPs, but was lower between the other polymorphisms. Of the possible 52 seven-locus haplotypes constructed, 10 were common, and were included in subsequent analysis. Increased frequency of CCCGGGG and CCCGGAA haplotypes, and reduced frequency of TCCGGGG and TCCGGGA haplotypes were seen in RM patients than in controls. When the Bonferroni correction was applied, differences were significant for the CCCGGAA haplotype, which was higher (OR=4.14; 95% CI=1.84-8.95), and the TCCGGGA haplotype, which were lower among RM cases (OR=0.09; 95% CI=0.02-0.68), thereby conferring RM susceptibility and protection to these haplotypes, respectively. Multivariate analysis confirmed the positive association of only CCCGGAA haplotype with RM (P=0.010; aOR=2.03; 95% CI=1.18-4.47), after controlling for a number of covariates. These results demonstrate that the TNFalpha polymorphisms, in particular the -1031T/C variant, are significantly associated with idiopathic RM. Additional replication studies on other racial groups are needed to confirm our findings.

Association of susceptibility to brucellosis and interleukin-4 promoter polymorphism

A C-T substitution at position 590 in the interleukin-4 (IL-4) gene is associated with increased production of IL-4. We sought to determine the associations between this polymorphism and susceptibility to brucellosis. DNA was extracted from the whole blood of 163 control individuals and 282 patients with brucellosis. A polymorphism in the IL-4 gene at position 590 from the promoter site was determined using an allele-specific PCR method. The prevalence of the T allele of IL-4 polymorphism was significantly higher in the patients group than in controls (28.9% vs 11.4%, p<0.004). Patients with brucellosis had a higher frequency of intermediate producer genotype (CT) (53.5% vs 22.7%, p<0.001) while low producer genotype (CC) was higher in the control group (77.3% vs 44.4%). Multiple logistic regression analysis demonstrated that patients who were heterozygous (CT) for interleukin-4 promoter polymorphism had a significantly higher risk for brucellosis with an odds ratio of 4.2 (95% CI 2.7-6.6, p<0.0001). Our findings demonstrate for the first time an association between IL-4 590 promoter polymorphism and contracting brucellosis in the Iranian population.

Cytokine gene polymorphisms in recurrent spontaneous abortions: a comprehensive review

PROBLEM

Cytokine gene polymorphism studies in women with recurrent spontaneous abortion (RSA) are reviewed to provide comprehensive understanding and a direction for the future investigation.

METHOD OF STUDY

A search of PubMed was made to identify the published data between 2001 and 2007 regarding RSA and cytokine gene polymorphisms.

RESULTS

Either allele and/or genotype frequencies of the following polymorphisms were reported to be significantly different between women with RSA and controls: IFN-gamma +874A-->T, TA (P = 0.01), AA (P = 0.04); IL-6, -634C-->G CG/GG (P = 0.026); IL-10, -592C-->A CC (P = 0.016); IL-1B -511C (P = 0.035), -31T (P = 0.029); IL-1RA, IL1RN*2 (P = 0.002), and IL1RN*3 (P = 0.002). None of these studies was repeatedly reported by others to be significantly different. Among these, four cytokine polymorphisms (IFN-gamma, +874A-->T; IL-1B -511C; IL-1RA, IL1RN*2, IL1RN*3) were refuted by others and rest of them were studied once.

CONCLUSION

Multiple cytokine polymorphisms were reported to be associated with RSA. However, a majority of studies were not confirmed by other investigators or refuted by others. Inconsistent study results might be related to: (i) the production of these cytokines is partly under genetic controls and other factors affect cytokine levels; (ii) ethnic background, environmental factors, and selection criteria for study populations are different and (iii) the possibilities exist that multiple cytokine gene polymorphisms or other genes in linkage disequilibrium may play a role in RSA.