The promoter region (-800, -509) polymorphisms of transforming growth factor-beta1 (TGF-beta1) gene and recurrent spontaneous abortion

TGF-β1 promoter functional gene polymorphism -509 C/T in the maternal susceptibility to recurrent pregnancy loss in South Indian women

Transforming growth factor beta 1 (TGF-β1) is an anti-inflammatory pleiotropic cytokine that regulates implantation and adhesion of trophoblasts to the extracellular matrix. It regulates the balance of Th1/Th2 cytokines and the generation of anti-inflammatory peripheral regulatory T cells (FOXP3 + Tregs), which is necessary for a healthy pregnancy. Single nucleotide polymorphisms (SNP) affecting TGF-β1 production/function may predispose to pregnancy loss. The aim of this study is to evaluate the association between the TGF-β1 -509C/T polymorphism, its serum concentrations, and recurrent pregnancy loss. The study comprised 150 RPL cases and 150 healthy controls for genotyping TGF-β1 -509C/T polymorphism using the Amplification Refractory Mutation System-Polymerase Chain Reaction (ARMS-PCR). Serum concentrations of TGF-β1 protein were estimated by enzyme-linked immunosorbent assay. From our study, women with CT genotype exhibited a protective role against RPL [OR (95 % CI) = 0.48(0.30-0.76), p = 0.002], while women with TT genotype had a significantly higher risk among RPL patients and exhibited twofold increased risk [OR (95 % CI) = 2.34(1.37-4.01), p = 0.002]. Observation of patient's follow-up data revealed a significant relation with CT genotype of unfavorable pregnancy outcome (CT vs. CC + TT, OR 2.46, 95 % C.I: 1.11-5.43, p = 0.039). Further, variant allele T was significantly elevated in women with unfavorable pregnancy compared with favorable pregnancy outcome, indicating considerable association of T allele in unfavorable pregnancy outcome (T vs. C, OR: 2.68, 95 % C.I: 1.52-4.74, p = <0.001). Serum concentrations of TGF-β1 have shown significant variation between patients and controls, as well as among RPL patients with favorable and unfavorable pregnancy outcome in correspondence to each genotype CC, CT, and TT (p < 0.05). Furthermore, genotype-dependent variation was observed within both the patient and control groups; however, this variation was not observed among RPL women with favorable and unfavorable pregnancy outcome. Our investigation revealed a significant influence of TGF-β1C-509 T polymorphism on RPL risk in South Indian 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.

Association of IL-1β, IL-6, TNF-α, and TGFβ1 Gene Polymorphisms with Recurrent Spontaneous Abortion in Polycystic Ovary Syndrome

Recurrent spontaneous abortion (RSA) is a common pregnancy-associated complication of polycystic ovary syndrome (PCOS) which is an endocrine malfunction disease. Patients with PCOS may have several underlying contributing and interrelated factors, which have been reported in women with RSA. The incidence rate between PCOS and RSA remains uncertain. The aim of this study is to determine the possible association of IL-1β-511C/T, IL-6-174G/C, TNF-α-1031T/C, and TGFβ1-509T/C with RSA patients with or without PCOS. A total of 140 RSA patients, 70 of which were PCOS patients, and 140 healthy females with no history of RSA or PCOS were included in this study. PCR amplification, genotyping, and sequence analysis were employed to investigate the presence of the polymorphisms. The genotypic and allelic frequencies were calculated separately for each subject. Out of the four studied polymorphisms, the IL-1β-511C/T genotype in RSA without PCOS patients (12.7%) was significantly different compared with that in control subjects (p = 0.047). For IL-6-174C/G, there was a tendency towards more CC carriers among RSA with PCOS patients (10%) than in controls (3%). The GG genotype in RSA women with PCOS (60%) was significantly different compared with that in control subjects (p = 0.033), and the GC genotype in RSA with PCOS patients (30%) showed a marginal significant difference compared with that in control subjects (p = 0.050). Significant difference was identified in the allelic frequencies in RSA patients with PCOS compared to controls (p = 0.025). IL-6-174G/C and TNF-α-1031T/C polymorphisms are significantly associated with RSA patients in Saudi patients with PCOS, while the IL-1β-511C/T polymorphism is significantly associated with RSA patients without PCOS.

Transforming growth factor beta1 (TGFβ1) polymorphisms and breast cancer risk

Transforming growth factor β1 (TGFβ1) is suggested to be involved in the pathogenesis of and in complications with breast cancer (BC). Polymorphisms in TGFβ1 gene (TGFβ1) have been suggested by many investigators to have a role in susceptibility to BC; however, many discordant data have been reported. Considering the role of ethnic variations, we performed an association study between TGFβ1 polymorphisms and BC among Iranian women. We sequenced DNA samples of 110 BC and 110 normal control women for the exons and their adjacent intronic regions of TGFβ1 using PCR. The allele, genotype, and haplotype frequencies were calculated using PowerMarker V3.25 and R 3.0.2 softwares. Ten single nucleotide polymorphisms (SNPs) were detected. Statistical analysis on the frequency of seven most frequent SNPs, including the three coding SNPs (cSNPs) revealed no significant difference between BC and control women. Moreover, among 11 constructed haplotypes, "GTGCCGC" was significantly different between two study groups. In conclusion, we found no association between the studied SNPs of TGFβ1 and BC among Iranian women, but a possible association between "GTGCCGC" haplotype and BC was seen. However, further studies are suggested to clarify this association.

Genetic variation in TGFB1 gene and risk of idiopathic recurrent pregnancy loss

Transforming growth factor β1 plays a significant role in pregnancy outcome. We investigated the association of TGFB1 exon 1 (rs1800471, rs1800470) and promoter region (rs1800469, rs1800468) polymorphisms with recurrent pregnancy loss (RPL) in 675 Tunisian women: 304 women with a history of three consecutive pregnancy losses of unknown etiology with the same partner and 371 age-matched multiparous control women. TGFB1 genotyping was done by TaqMan assays. Higher minor allele frequency for rs1800471 (P< 0.001), but not for rs1800470, rs1800469 or rs1800468 was found in RPL cases compared with controls. A significant difference in the distribution of rs1800471 genotypes was seen between the RPL cases and control women, irrespective of the genetic model used. Increased RPL risk was seen with rs1800471 allele C in the heterozygous state and to a greater degree in the homozygous state, thus establishing a dose-dependent effect. Haploview analysis revealed differential linkage disequilibrium between the TGFB1 single-nucleotide polymorphisms analyzed. TGFB1 haplotype analysis identified eight common haplotypes (rs1800471/rs1800470/rs1800469/rs1800468) with three (GTTG, Pc = 0.02; CCTG, Pc = 0.02 and CTCG, Pc = 0.02) positively associated with RPL and one (GCCG, Pc = 0.009) negatively associated with RPL. This study provides the first evidence that the TGFB1 genotype may influence RPL.

Promoter region polymorphisms in the transforming growth factor beta-1 (TGFβ1) gene and serum TGFβ1 concentration in preeclamptic and control Iranian women

Preeclampsia (PE) is a pregnancy associated disorder characterized by hypertension and proteinuria, which causes neonatal and maternal morbidity and mortality. The Th1/Th2 cytokine paradigm of the immune adaptation in pregnancy is now expanded to include Th1/Th2/Th17 and regulatory T (Treg) cells. Among cytokines, TGFβ1 has properties that justify evaluation of its role in PE etiopathology. In this investigation the polymorphisms of the TGFβ1 gene at promoter region, positions -800G→A and -509C→T, were studied in 142 PE and 140 normal pregnant female subjects using PCR-RFLP. Additionally, serum TGFβ1 was determined by ELISA. At position -800G→A genotypes and allele frequencies showed no significant differences between PE patients (GG 73.9%; GA 21.1%; AA 4.93%) and normal control (GG 70%; GA 28.6%; AA 1.4%) women. However the AA genotype at this position was more frequent in PE patients than in the control group. At -509C→T position, genotypes and allele frequencies showed no significant differences between PE patients and control individuals. The CC genotype at -509C→T position was more prevalent in PE patients than in the control group. The mean serum TGFβ1 level was significantly higher (62.14 ng/ml) in PE patients compared with pregnant and non-pregnant control groups (and 47.01 and 40.68 ng/ml, respectively). In conclusion, the promoter region polymorphisms of TGFβ1 may not be associated with PE, but serum levels of this cytokine may contribute to the etiopathology of PE.

Promoter polymorphism of transforming growth factor-beta1 gene and ulcerative colitis

AIM

To elucidate the possible difference in two promoter polymorphisms of the transforming growth factor-beta1 (TGF-beta1) gene (-800G > A, -509C > T) between ulcerative colitis (UC) patients and normal subjects.

METHODS

A total of 155 patients with established ulcerative colitis and 139 normal subjects were selected as controls. Two single nucleotide polymorphisms within the promoter region of TGF-beta1 gene (-509C > T and -800G > A) were genotyped using PCR-RFLP.

RESULTS

There was a statistically significant difference in genotype and allele frequency distributions between UC patients and controls for the -800G > A polymorphism of the TGF-beta1 gene (P < 0.05). The frequency of the TGF-beta1 gene polymorphism at position -800 showed that the AA genotype and the allele A frequencies significantly differed between the patients and healthy controls (P < 0.05). At position -509, there was no statically significant difference in genotype and allele frequency between the patients and control subjects.

CONCLUSION

The results of our study indicate that there is a significant difference in both allele and genotype frequency at position -800G > A of TGF-beta1 gene promoter between Iranian patients with UC and normal subjects.

Interleukin-18 gene promoter polymorphisms and recurrent spontaneous abortion

BACKGROUND

IL-18 is a multifunctional cytokine capable of inducing either Th1 or Th2 polarization depending on the immunologic milieu. IL-18 is detected at the materno-fetal interface very soon in early pregnancy. Two polymorphisms in the promoter region of the IL-18 gene at positions of -607 and -137 appear to have functional impacts.

OBJECTIVE

This study attempts to evaluate the frequency of these two polymorphisms in the IL-18 gene promoter in patients with recurrent spontaneous abortion (RSA) and normal pregnant women.

SUBJECTS AND METHODS

One hundred and two RSA patients and 103 healthy pregnant women were enrolled in this study. Single nucleotide polymorphisms of the IL-18 gene at positions -607 (C/A) and -137 (G/C) were analyzed by the sequence-specific PCR method.

RESULTS

There was no significant association between the allele, genotype, and haplotype frequencies of the two single nucleotide polymorphisms (SNPs) in the IL-18 gene promoter and RSA.

CONCLUSION

The results of this study showed that IL-18 gene promoter polymorphisms at positions -607 and -137 did not confer susceptibility to RSA in southern Iranian patients.

Lack of association between the TGF-beta1 gene polymorphisms and recurrent spontaneous abortion

Transforming growth factor-beta1 (TGF-beta1) is produced by T regulatory lymphocytes (Treg), which play an important role in the physiology of pregnancy. Several polymorphisms of the TGF-beta1 gene (TGFB1) have been reported, some with an important correlation with TGF-beta1 production and disease severity. We performed an association study between TGFB1 polymorphisms and recurrent spontaneous abortion (RSA). We first used a PCR-RFLP method to detect three known TGFB1 cSNPs (coding single nucleotide polymorphisms) among 111 RSA and 110 normal control women from Southern Iran, such as 29T-->C (Leu 10 Pro), 74G-->C (Arg 25 Pro) and 788C-->T (Thr 263Ile), and compared their frequencies between the two groups of subjects. To confirm results of the RFLP study and to identify new SNPs in the RSA women, we then sequenced their DNA samples for seven exons and adjacent intronic regions of TGFB1. Consequently, 10 SNPs were detected; one (-14G-->A) was located in the upstream region of exon 1, three in exons (two in exon 1 and one in exon 5) and six in intronic regions. Two (IVS5+18G-->C and IVS6+910G-->A) of the 10 SNPs were novel. Statistical analysis on the frequency of six most frequent SNPs, including the three cSNPs, as well as on the frequencies of genotypes and 13 haplotypes regarding the 6 SNPs, revealed no significant difference between RSA and control women. Therefore, this study concludes that there is no association between exonic and adjacent intronic polymorphisms of TGFB1 and RSA.