A case-control study in IL6 and TGFB1 gene polymorphisms and recurrent spontaneous abortion in southern Brazilian patients

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.

Manipulation of Interleukin-6 (IL-6) and Transforming Growth Factor Beta-1(TGFβ-1) towards viral induced liver cancer pathogenesis

Hepatocellular carcinoma (HCC) is the most common liver malignancy. Early diagnosis of HCC has always been challenging. This study aims to assess the pathogenicity and the prevalence of IL-6 -174G/C (rs1800795) and TGFβ-1 +29C/T (rs1800470) polymorphisms in HCV-infected HCC patients. Experimental strategies are integrated with computational approaches to analyse the pathogenicity of the TGFβ-1 +29C/T and IL-6-174 G/C polymorphisms in HCV-induced HCC. AliBaba2 was used to predict the effect of IL-6-174 G/C on transcription factor binding site in IL-6 gene. Structural changes in the mutant TGFβ-1 structure were determined through project HOPE. To assess the polymorphic prevalence of IL-6 -174G/C and TGFβ-1 +29C/T genotypes in HCC and control subjects, amplification refractory mutation system PCR (ARMS-PCR) was performed on 213 HCC and 216 control samples. GraphPad Prism version 8.0 was used for the statistical analysis of the results. In-silico analysis revealed the regulatory nature of both IL-6 -174G/C and TGFβ-1 +29C/T polymorphisms. ARMS-PCR results revealed that the individuals carrying TT genotype for TGFβ-1 gene have an increased risk of developing HCC (p<0.0001, OR = 5.403, RR = 2.062) as compared to individuals with CT and CC genotype. Similarly, GC genotype carriers for IL-6 gene exhibit an increased risk of HCC susceptibility (p<0.0001, OR = 2.276, RR = 1.512) as compared to the people carrying the GG genotype. Genotype TT of TGFβ-1 gene and genotype GC of IL-6 gene are found to be associated with HCV-induced HCC. IL-6 polymorphism may alter its transcription that leads to its pathogenicity. TGFβ-1 polymorphism may alter protein structure stability.

The hormetic and hermetic role of IL-6

Interleukin-6 is a pleiotropic cytokine regulating different tissues and organs in diverse and sometimes discrepant ways. The dual and sometime hermetic nature of IL-6 action has been highlighted in several contexts and can be explained by the concept of hormesis, in which beneficial or toxic effects can be induced by the same molecule depending on the intensity, persistence, and nature of the stimulation. According with hormesis, a low and/or controlled IL-6 release is associated with anti-inflammatory, antioxidant, and pro-myogenic actions, whereas increased systemic levels of IL-6 can induce pro-inflammatory, pro-oxidant and pro-fibrotic responses. However, many aspects regarding the multifaceted action of IL-6 and the complex nature of its signal transduction remains to be fully elucidated. In this review we collect mechanistic insight into the molecular networks contributing to normal or pathologic changes during advancing age and in chronic diseases. We point out the involvement of IL-6 deregulation in aging-related diseases, dissecting the hormetic action of this key mediator in different tissues, with a special focus on skeletal muscle. Since IL-6 can act as an enhancer of detrimental factor associated with both aging and pathologic conditions, such as chronic inflammation and oxidative stress, this cytokine could represent a "Gerokine", a determinant of the switch from physiologic aging to age-related diseases.

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)

AIM

We aimed to evaluate the genetic variation of tumor necrosis factor-α (TNF-α) 308 G>A (rs1800629) and transforming growth factor (TGF) β1G>C (rs1800471) to confer risk in patients with recurrent miscarriage in highly consanguineous population of Kashmir (North India).

METHODS

A total of 200 women who experienced two or more recurrent miscarriages (along with 100 spouses, 60 products of conception, and 240 healthy controls) with two or more full-term pregnancies were recruited from the same geographical region and evaluated by polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

TNF-α 308 G>A variant genotype (AA) was significantly associated with recurrent miscarriage cases (2.5% vs. 0.4% controls, respectively; p < 0.05) and its per copy allele A also presented more in cases (32% vs. 24% in controls; p < 0.05) that showed a risk of 1.5-fold for cases (p < 0.05). The difference of variant genotype GA was observed to be significant among recurrent miscarriage cases and product of conception: 60.5% vs. 83%, respectively (p < 0.05) wherein variant TNF-α GA genotype conferred 3-fold risk (p < 0.05). On the other hand, TGF β1 G>C showed no association with recurrent miscarriage cases in our population.

CONCLUSION

The study found both TNF-α 308 G>A variants are significantly associated with an increased susceptibility for recurrent miscarriages to cause pregnancy losses but on the other hand TGF β1 does not seem to impact the outcome of pregnancy in our population.

Association of Promoter Region Polymorphisms of IL-6 and IL-18 Genes with Risk of Recurrent Pregnancy Loss: A Systematic Review and Meta-Analysis

Background: The present meta-analysis was performed to investigate the association of promoter region polymorphisms at IL-6 and IL-18 genes with recurrent pregnancy loss (RPL) risk. Methods: An electronic search of the PubMed, Embase, ISI Web of Knowledge and CNKI databases was performed to identify eligible studies up to May 30, 2019. Results: A total of 31 case-control studies were finally selected. Significant associations with the risk of RPL were detected for the IL-6 -174 G > C, -634 G > C and IL-18 -137 G > C polymorphisms in overall population. Further, subgroup analyses by ethnicity revealed that the IL-6 -174 G > C and -634 G > C polymorphisms were significantly associated with risk of RPL risk in Asians. Conclusions: Our results suggest that the IL-6 -174 G > C, -634 G > C and IL-18 -137 G > C polymorphisms may contribute to the susceptibility of RPL. The IL-18 -607 C > A polymorphism does not appear to influence the development of 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.

Associations between tumor necrosis factor-α and interleukin-6 polymorphisms and unexplained recurrent spontaneous abortion risk: A meta-analysis

To evaluate the associations between Tumor necrosis factor-α (TNF-α)(-238G>A) and Interleukin-6 (IL-6)(-174G>C) polymorphism and risk of unexplained recurrent spontaneous abortion (URSA).Correlated case-control studies were collected by computer retrieval. A meta-analysis was conducted by Stata 12.0 software to analysis the strength of association between polymorphism of TNF-α -238G>A and IL-6 -174G>C and URSA.Twenty-one articles with twenty-two studies were included, of which 12 and 10 studies were respectively related to mutation of TNF-α -238G>A, IL-6 -174G>C and URSA. The integrated results showed that the TNF-α-238G>A gene mutation was significantly correlated with the risk of URSA under homozygote model (AA vs GG;OR 1.533,95% CI 1.022-2.301) and recessive model (AA vs GG+AG;OR 1.571,95%CI 1.050-2.350)(P < .05). There was no association between URSA and TNF-α -238G>A under heterozygote model (AG vs GG;OR 0.963,95% CI 0.816-1.137), dominant model (AA+AG vs GG; OR 1.031,95%CI 0.880-1.209) and additive model (A vs G;OR 1.046,95%CI 0.909-1.203)(P > .05). The results of subgroup analysis based on ethnicity showed that -238G>A was significantly correlated with the risk of URSA in Asians under all gene models except for heterozygote model (AG vs GG; OR 1.129,95% CI 0.857-1.487) (P < .05). In Caucasians, it was dominant model (AA+AG vs GG; OR 1.430,95%CI 1.040-1.965) (P < .05) rather than others that showed relationship with URSA. From the integrated results, association was manifested between -174G>C and URSA under all gene models (P < .05) except for recessive model (CC vs GG+CG, OR 1.166, 95%CI 0.938-1.449) (P > .05), which is identical to subgroup analysis based on ethnicity.It is of great guiding significance for screening out and preventing URSA among high-risk women to test on TNF-α -238G>A and IL-6 -174G>C under gene models mentioned above which are highly associated with the risk of URSA, which can act as biological markers for URSA.

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.

Hall of Fame among Pro-inflammatory Cytokines: Interleukin-6 Gene and Its Transcriptional Regulation Mechanisms

Pro-inflammatory cytokines that are generated by immune system cells and mediate many kinds of immune responses are kinds of endogenous polypeptides. They are also the effectors of the autoimmune system. It is generally accepted that interleukin (IL)-4, IL-6, IL-9, IL-17, and tumor necrosis factor-α are pro-inflammatory cytokines; however, IL-6 becomes a protagonist among them since it predominately induces pro-inflammatory signaling and regulates massive cellular processes. It has been ascertained that IL-6 is associated with a large number of diseases with inflammatory background, such as anemia of chronic diseases, angiogenesis acute-phase response, bone metabolism, cartilage metabolism, and multiple cancers. Despite great progress in the relative field, the targeted regulation of IL-6 response for therapeutic benefits remains incompletely to be understood. Therefore, it is conceivable that understanding mechanisms of IL-6 from the perspective of gene regulation can better facilitate to determine the pathogenesis of the disease, providing more solid scientific basis for clinical treatment translation. In this review, we summarize the candidate genes that have been implicated in clinical target therapy from the perspective of gene transcription regulation.

Infectious diseases, IL6 -174G>C polymorphism, and human development

Interleukin-6 (IL6) is a pro-inflammatory cytokine that is required for resistance against many pathogens. However, sustained IL6 activity can cause tissue damage in the periphery and brain. Previous studies have shown that populations in disease-endemic regions adapt by selecting the high-producing G-allele at the -174G>C (rs1800795) polymorphism, while others have linked increased IL6 to cognitive impairments. The present study sought to determine whether up-regulation of IL6 by the G-allele at rs1800795 polymorphism in disease-endemic regions was associated with increased cognitive deficits and corollary reductions in social, economic, and political development. We tested these hypotheses in a global sample of 189 nations with World Health Organization ratings for infectious diseases. We also included the Historical Pathogen Prevalence index, a measure of national average intelligence (IQ), and the United Nation Human Development Index (HDI) including per capita income, life expectancy, child mortality, and fertility rate. IL6 -174G>C allele frequencies were obtained from 171,168 individuals spanning 84 nations. The high-producing G-allele frequency was positively correlated with infectious disease ranking (r=0.745, P<0.001) and negatively with IQ (r=-0.524, P<0.001) and HDI (r=-0.671, P<0.001). These robust findings suggest that in regions with a high pathogen burden the need for a strong IL6 response is accompanied by cognitive deficits and reduced HDI ranking.

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.

Interleukin-6 level and gene polymorphism in spontaneous miscarriage

The aetiology of spontaneous miscarriage, the most common pregnancy complication, remains undefined. One of postulated factors involved in miscarriage pathology is interleukin 6 (IL-6). Therefore, the aim of the study was to evaluate IL-6 and interleukin 6 receptor (IL-6R) gene polymorphisms in patients with spontaneous miscarriage. One hundred fifty-seven patients diagnosed with spontaneous miscarriage and age and gestational time matched controls were included in the case-control study. In all study participants circulating IL-6 levels (chemiluminescent immunoassay) and IL6-174G>C as well as IL6R rs2228145:A>C polymorphisms were evaluated. The distribution of IL6 as well as IL6R alleles and genotypes were similar in the controls and patients with miscarriage. Only a trend of more frequent appearance of -174GC+CC and C allele in the patients with miscarriage was noted. Blood serum concentrations of IL-6 were significantly elevated in patients with miscarriage vs those with physiological pregnancy. Likewise, IL-6 concentrations differ significantly with the types of miscarriage. The highest concentrations of the cytokine was seen in subjects with incomplete miscarriage (4.28 ± 4.88 pg/ml) followed by imminent miscarriage (2.97 ± 2.42 pg/ml), and then missed miscarriage (2.07 ± 1.90 pg/ml), being significantly the lowest in missed miscarriage group. No association between the IL6 genotype and IL-6 serum concentration were noted, both in the miscarriage group and in the control group. The findings of the study support the role of IL-6 in spontaneous miscarriage irrespectively of its type. However, no correlation between circulating IL-6 and IL6 gene polymorphism, as well as IL-6 and IL-6R polymorphisms associations with spontaneous miscarriage were revealed.

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.

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 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.

Mannan-binding lectin levels related to spontaneous abortion in Brazilian patients with celiac disease

Low concentration of mannan-binding lectin (MBL) has been related to unexplained spontaneous abortion (SA), which has also been observed in an increased frequency in patients with celiac disease (CD). In this study, plasma levels of MBL were determined in patients with CD and irritable bowel syndrome (IBS) in order to investigate whether there is an association of MBL levels and the occurrence of SA in these patients. MBL concentration was determined in 46 patients with CD (28 without and 18 with report of SA) and 38 patients with IBS (25 without and 13 with report of SA). A higher frequency of SA was observed in women with CD when compared to IBS patients (23.2 vs. 13.9%; P = 0.046). No significant difference was observed in MBL concentrations between patients with CD, IBS, and healthy controls, nor between patients with or without occurrence of SA. These results suggest that the serum levels of MBL and the occurrence of SA in women with CD and IBS are not causally related.

Interleukin-6 -174 genotype, periodontal disease and adverse pregnancy outcomes: a pilot study

This study was undertaken to investigate whether maternal periodontal disease and variant genotypes of IL-6 gene are associated with adverse pregnancy outcomes. A total of 145 pregnant women were recruited from St Mary's Hospital, Manchester, UK. Bleeding on probing (BOP) and pocket depth indices were recorded on all teeth. Amplification refractory mutation system-polymerase chain reaction was used for -174 IL-6 genotyping. Birth weight was assessed using the individualized birth ratio (IBR) with intrauterine growth restriction (IUGR) defined as an IBR below the fifth percentile. The G/G genotype results in more BOP % sites in Caucasian (P < 0.001) and Afro-Caribbean pregnant women (P = 0.035). In addition, a marginal significant association between the -174 C/C genotype and IUGR was observed (P = 0.06). The -174* C allele was more frequent in women with IUGR than in normal women (63 vs 37%, P = 0.05). Moreover, the combination between the carriage of -174C allele and increased bleeding sites have increased the risk of IUGR (P = 0.006). Future studies, with a larger sample size, are required to better clarify the relationship between the IL-6 gene polymorphism, periodontal disease, and IUGR.

Cytokine polymorphisms in women with recurrent pregnancy loss: meta-analysis

BACKGROUND

Inflammatory cytokine cascades have been implicated in the pathogenesis of recurrent pregnancy loss (RPL). Polymorphisms in cytokine genes may affect the risk of RPL, but genetic association studies are often limited by small sample sizes. Meta-analysis of all available studies can increase the precision of these estimates.

AIMS

To assess and synthesise the available data from association studies of inflammatory cytokine polymorphisms with RPL.

METHODS

Systematic review and random effects meta-analysis of genetic association studies.

RESULTS

Sixteen reports of genetic association studies of cytokine polymorphisms with RPL were identified. Meta-analyses did not identify any significant associations with tumour necrosis factor (-308A, or -238A), interferon-gamma (+874T), interleukin (IL)-1beta (-511T), IL-6 (-174G), or IL-10 (-1082A, or -819T, or -592A). Significant associations were found with IL-1B (-31T) (two studies: pooled odds ratio (OR) 2.12 (95% confidence interval (CI) 1.04 to 4.33)) and IL-6 (-634G) (one study: OR 0.22 (95% CI 0.09 to 0.57)).

CONCLUSIONS

The available data are not consistent with more than modest associations between these candidate cytokine polymorphisms and RPL. Data from future association studies may be added to the meta-analyses to obtain more precise estimates of effect sizes.

Promoter polymorphism of transforming growth factor-β1 gene and ulcerative colitis

AIM: To elucidate the possible difference in two promoter polymorphisms of the transforming growth factor-β1 (TGF-β1) 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-β1 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-β1 gene (P < 0.05). The frequency of the TGF-β1 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-β1 gene promoter between Iranian patients with UC and normal subjects.

Elevated circulating IL-1beta and TNF-alpha, and unaltered IL-6 in first-trimester pregnancies complicated by threatened abortion with an adverse outcome

The purpose of the present study was to examine the profile of selected proinflammatory cytokines in maternal serum of first-trimester pregnancies complicated by threatened abortion (TACP) and its relevance to obstetric outcome. Serum levels of Th1-type cytokines interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-alpha), and Th2-type cytokine interleukin 6 (IL-6) were measured, by ELISA, in 22 women with TACP and adverse outcome at admission (group A) and compared with the corresponding levels of 31 gestational age-matched women with TACP and successful outcome at admission (group B1) and discharge (group B2) and 22 gestational age-matched women with first-trimester uncomplicated pregnancy (group C) who served as controls. Mann-Whitney U or Wilcoxon test was applied as appropriate to compare differences between groups. IL-1β and TNF-alpha were detected with significantly higher levels in group A, compared to all other groups. On the contrary, IL-6 levels were detected with no significant difference among all the other groups studied. It is concluded that in first-trimester TACP with adverse outcome, a distinct immune response, as reflected by elevated maternal IL-1β, TNF-alpha, and unaltered IL-6 levels, is relevant to a negative obstetric outcome.

Inflammation and miscarriage

Most relevant studies in animals and humans indicate that some degree of systemic or uterine inflammation is necessary both for normal implantation and pregnancy. However, if inflammation becomes too excessive it might cause pregnancy complications such as fetal resorption/miscarriage. The main regulator of the correct level of inflammation at the feto-maternal interface seems to be the uterine CD16(-) CD56(bright) natural killer (NK) cells. Trophoblast debris, apoptotic cells and progesterone probably stimulate/regulate the production of inflammatory cytokines from these cells. Miscarriage of karyotypically normal embryos may occur when the level of inflammation at the feto-maternal interface falls outside the optimal range. This may be caused by an insufficient influx of CD56(bright) NK cells into the decidua, too little soluble histocompatibility leukocyte antigen (HLA)-G secretion from the trophoblast, hypersecretion of inflammatory cytokines due to the presence of high-production polymorphisms, presence of maternal HLA-DR alleles associated with high tumor necrosis factor (TNF)-alpha production, or maternal mannose-binding lectin deficiency.

Nutrition and developmental biology--implications for public health

Recent advances in understanding genome-nutrient and nutrient-network interactions, and the modifying effects of genetic variation on their function, have strengthened interests in acute and long-lasting diet/ nutrition influences on health. Relationships between early and mid-gestational and perinatal conditions (including those related to maternal nutrition) and outcomes, and later-onset chronic diseases have received particular attention. Controlled animal experiments support views that responses with long-lasting effects to nutritional milieus are enabled by epigenetic and other metabolic adjustments during critical windows. Thus, underlying mechanisms are beginning to be understood. For example, chromatin remodeling during development can alter gene expression levels, fix or determine future set points critical to intra- and inter-organ communication networks, alter morphogenesis, initiate remodeling events, etc., all with lifelong consequences. These also may affect DNA mutation rates and thereby influence adult cancer and other risks. There is increasing evidence that nutrient-based strategies will be of value to the prevention or delay of onset of chronic diseases and that these strategies may require initiation during embryonic or fetal stages of development to achieve maximal benefit.