Association between the interleukin-6 gene -572 C/G polymorphism and the risk of type 2 diabetes mellitus: a meta-analysis of 11,681 subjects

Interleukins-6 -174G/C (rs1800795) and -572C/G (rs1800796) polymorphisms and prostate cancer risk

Prostate cancer (PCa) is an aggressive cancer influenced by a complex interplay of genetic and environmental factors. Amongst these risk factors, the impact of Interleukin6 (IL6) gene polymorphisms in PCa risk has received a lot of attention. IL-6 is a cytokine that has been implicated in the pathogenesis of several malignancies, including PCa. Two IL-6 gene polymorphisms, - 174 G/C (rs1800795) and - 572 C/G (rs1800796), have received intellectual attention due to their potential role as modulators of prostate cancer risk. The main objective of this research was to comprehensively explore the potential associations between IL-6 rs1800795 and rs1800796 polymorphisms, and their impact on the occurrence of PCa. A case-control study was carried out with a well-defined cohort comprising 110 PCa cases and 110 controls (total n = 220). The genotyping of rs1800795 and rs1800796 was carefully performed using the highly sensitive and accurate Polymerase Chain Reaction-High Resolution Melting Curve (PCR-HRM) technique. The assessment of genetic associations was evaluated using various R packages, such as Haplo-Stats, SNP stat, pheatmap, and LD heatmap. The present study applied odds ratio (OR) analysis to reveal significant evidence of strong associations between the genotypes of rs1800795 and rs1800796 and the susceptibility to PCa. The findings of this study underscore the noteworthy impact of genetic variations in the IL-6 gene on the development of prostate cancer. Specifically, the C/G and G/G genotypes of rs1800795 demonstrated increased PCa risk, with odds ratios (OR) of 1.650 (95% CI = 1.068-2.549, p = 0.032) and 2.475 (95% CI = 1.215-5.043, p < 0.001), respectively. Similarly, the G/C genotype of rs1800796 exhibited an OR of 2.374 (95% CI = 1.363-4.130, p = 0.012) for elevated prostate cancer risk, while the C/C genotype had an OR of 1.81 (95% CI = 1.02-3.22, p = 0.7). Furthermore, our haplotype analysis have revealed an association between haplotype 4 (C-G) and increased risk of PCa (OR = 1.69, 95% CI = 1.05-2.73, p = 0.032). In conclusion, this case-control analysis presents compelling evidence for a significant association between IL-6 variants (rs1800795 and rs1800796) and increased susceptibility to prostate cancer.

Dietary Acid Load and Its Interaction with IGF1 (rs35767 and rs7136446) and IL6 (rs1800796) Polymorphisms on Metabolic Traits among Postmenopausal Women

The objective of this study was to explore the effects of dietary acid load (DAL) and IGF1 and IL6 gene polymorphisms and their potential diet–gene interactions on metabolic traits. A total of 211 community-dwelling postmenopausal women were recruited. DAL was estimated using potential renal acid load (PRAL). Blood was drawn for biochemical parameters and DNA was extracted and Agena^® MassARRAY was used for genotyping analysis to identify the signalling of IGF1 (rs35767 and rs7136446) and IL6 (rs1800796) polymorphisms. Interactions between diet and genetic polymorphisms were assessed using regression analysis. The result showed that DAL was positively associated with fasting blood glucose (FBG) (β = 0.147, p < 0.05) and there was significant interaction effect between DAL and IL6 with systolic blood pressure (SBP) (β = 0.19, p = 0.041). In conclusion, these findings did not support the interaction effects between DAL and IGF1 and IL6 single nucleotide polymorphisms (rs35767, rs7136446, and rs1800796) on metabolic traits, except for SBP. Besides, higher DAL was associated with higher FBG, allowing us to postulate that high DAL is a potential risk factor for diabetes.

Association of NFκβ, TNFα, IL-6, IL-1β, and LPL Polymorphisms with Type 2 Diabetes Mellitus and Biochemical Parameters in a Mexican Population

Chronic low-grade inflammation is strongly related to the etiology of diabetes mellitus type 2 (T2DM), and the expression of inflammatory cytokines may be modulated by polymorphisms located in the regulatory regions of the NFκβ, IL-1β, IL-6, TNFα, and LPL genes. We considered it particularly important to investigate the relationship of gene polymorphisms involved in chronic inflammation with the risk of T2DM or uncontrolled biochemical parameters.

METHODS

We included 199 individuals with a T2DM diagnosis and 213 individuals without a T2DM diagnosis. Restriction fragment length polymorphism (RFLP) analyses were used to assess polymorphisms.

RESULTS

We found a risk association between T2DM and uncontrolled biochemical parameters in a Mexican population for the genotypes del/del of NFκβ, -174 and -572 of IL-6, C/C of IL-1β, -308 and -238 of TNFα, and T/T of LPL. In subjects without diabetes (controls), we found an association between the G/C genotype of the -572 polymorphism and the G/C and C/C genotypes of the -597 polymorphism of IL-6 with the risk of glucose levels > 131 mg/dL. Genotype C/C of polymorphism -174 of the IL-6 gene was associated with high triglyceride levels, and levels > 5.8% of HbA1c were associated with the G/A genotype of TNFα -308.

CONCLUSION

Here, we describe for the first time the relationship of T2DM risk and uncontrolled biochemical parameters with polymorphisms in the NFκβ, IL-6, TNFα, IL-1β, and LPL genes in a Mexican population. We also showed that for the population included in this study, there is an additive effect of the polymorphisms of the studied genes that considerably increases the risk of developing T2DM.We also showed that there are interactions between genes related to chronic inflammation that affect the risk of T2DM.

Interleukin-6-174G/C polymorphism is associated with a decreased risk of type 2 diabetes in patients with chronic hepatitis C virus

BACKGROUND

Chronic hepatitis C (CHC) is associated with type 2 diabetes mellitus. Although the pathogenesis remains to be elucidated, a growing evidence has suggested a role of pro-inflammatory immune response. Increased serum concentrations of Interleukin 6 (IL-6) have been associated with insulin resistance, type 2 diabetes mellitus as well as advanced forms of liver disease in chronic hepatitis C infection.

AIM

To investigate the frequency of IL-6-174G/C (rs1800795) single nucleotide polymorphism (SNP) in CHC patients and in healthy subjects of the same ethnicity. Associations between type 2 diabetes mellitus (dependent variable) and demographic, clinical, nutritional, virological and, IL-6 genotyping data were also investigated in CHC patients.

METHODS

Two hundred and forty-five patients with CHC and 179 healthy control subjects (blood donors) were prospectively included. Type 2 diabetes mellitus was diagnosed according to the criteria of the American Diabetes Association. Clinical, biochemical, histological and radiological methods were used for the diagnosis of the liver disease. IL-6 polymorphism was evaluated by Taqman SNP genotyping assay. The data were analysed by logistic regression models.

RESULTS

Type 2 diabetes mellitus, blood hypertension and liver cirrhosis were observed in 20.8% (51/245), 40.0% (98/245) and 38.4% (94/245) of the patients, respectively. The frequency of the studied IL-6 SNP did not differ between the CHC patients and controls (P = 0.81) and all alleles were in Hardy-Weinberg equilibrium (P = 0.38). In the multivariate analysis, type 2 diabetes mellitus was inversely associated with GC and CC genotypes of IL-6-174 (OR = 0.42; 95%CI = 0.22-0.78; P = 0.006) and positively associated with blood hypertension (OR = 5.56; 95%CI = 2.79-11.09; P < 0.001).

CONCLUSION

This study was the first to show that GC and CC genotypes of IL-6-174 SNP are associated with a decreased risk of type 2 diabetes mellitus in patients chronically infected with hepatitis C virus. The identification of potential inflammatory mediators involved in the crosstalk between hepatitis C virus and the axis pancreas-liver remains important issues that deserve further investigations.

Genetic Relationship Between IL-6 rs1800796 Polymorphism and Susceptibility to Periodontitis

BACKGROUND

There are accumulating reports for the potential role of Interleukin-6 (IL-6) rs1800796 polymorphism in the risk of periodontitis. However, distinct conclusions are observed. In this study, we have an interest in comprehensively analyzing the genetic relationship between IL-6 rs1800796 and the susceptibility to periodontitis.

METHODS

We retrieved the eligible case-control studies from on-line database and conducted a meta-analysis. P-value of association test, OR (odd ratios) and 95% CI (confidence interval) were calculated for the assessment of potential genetic association.

RESULTS

We enrolled a total of 20 case-control studies for pooling analysis. A positive association between periodontitis cases and controls was observed in the overall meta-analysis under all genetic models (all P < 0.05, OR > 1). Similar results were detected in the "population-based, PB" and "China" subgroups (all P < 0.05, OR > 1). In the "Asian" subgroup, there is an increased periodontitis risk under the allele, homozygote, heterozygote, dominant and carrier models (all P < 0.05, OR > 1). Nevertheless, negative results were found in the "Caucasian" subgroup under all models [all P > 0.05]. In addition, a positive association between IL-6 rs1800796 and the risk of chronic periodontitis was detected under the models of allele [G vs. C], GG vs. CC, GG vs. CC+ CG and carrier [G vs. C] (all P < 0.05, OR > 1).

CONCLUSION

IL-6 rs1800796 may serve as one genetic risk factor for periodontitis patients in the Asian population, especially the Chinese population. G/G genotype of IL-6 rs1800796 appears to be associated with an increased risk of chronic periodontitis.

CRP genetic variants are associated with mortality and depressive symptoms in chronic heart failure patients

OBJECTIVE

Heart failure (HF) is a complex medical condition with a multitude of genetic and other factors being involved in the pathogenesis. Emerging evidence points to an involvement of inflammatory mechanisms at least in subgroups of patients. The same is true for depression and depressive symptoms, which have a high prevalence in HF patients and are risk factors for the development and outcomes of cardiovascular disease.

METHODS

In 936 patients of the Interdisciplinary Network Heart Failure (INH) program, CRP and IL-6 protein blood levels were measured and genetic variants (single nucleotide polymorphisms) of the CRP and IL6 gene analyzed regarding their influence on mortality.

RESULTS

Less common recessive genotypes of two single nucleotide polymorphisms in the CRP gene (rs1800947 and rs11265263) were associated with significantly higher mortality risk (p < 0.006), higher CRP levels (p = 0.029, p = 0.006) and increased depressive symptoms in the PHQ-9 (p = 0.005, p = 0.003). Variants in the IL-6 gene were not associated with mortality.

CONCLUSION

Our results hint towards an association of less common CRP genetic variants with increased mortality risk, depressive symptoms and peripheral CRP levels in this population of HF patients thereby suggesting a possible role of the inflammatory system as link between poor prognosis in HF and depressive symptoms.

Association of interleukin-6 polymorphisms with obesity or metabolic traits in young Mexican-Americans

Objective

The objective of the study is to investigate the association of interleukin-6 (IL6) promoter single-nucleotide polymorphisms rs1800797 (-597 G/A) and rs1800796 (-572 G/C) with obesity or metabolic syndrome in Mexican-Americans.

Methods

The rs1800797 and rs1800796 single-nucleotide polymorphisms were genotyped in Mexican-Americans (n = 437) from South Texas, and results were correlated with measures of obesity and metabolic syndrome including body mass index, waist circumference, blood pressure, cholesterol, triglycerides, glucose, liver enzymes, plasma IL6 and high-sensitive C-reactive protein (hs-CRP).

Results

Significant associations were found for the rs1800796 variant with increased waist circumference, insulin resistance, lower IL6 levels and higher hs-CRP levels. The rs1800797 variant showed no associations with metabolic traits but was associated with higher IL6 levels and lower hs-CRP levels.

Conclusions

Findings in this study support the anti-inflammatory, anti-obesity and glucose homeostatic roles of IL6 in Mexican-American youth.

Current Advances in Pharmacotherapy and Technology for Diabetic Retinopathy: A Systematic Review

Diabetic retinopathy (DR) is classically defined by its vascular lesions and damage in the neurons of the retina. The cellular and clinical elements of DR have many features of chronic inflammation. Understanding the individual cell-specific inflammatory changes in the retina may lead to novel therapeutic approaches to prevent vision loss. The systematic use of available pharmacotherapy has been reported as a useful adjunct tool to laser photocoagulation, a gold standard therapy for DR. Direct injections or intravitreal anti-inflammatory and antiangiogenesis agents are widely used pharmacotherapy to effectively treat DR and diabetic macular edema (DME). However, their effectiveness is short term, and the delivery system is often associated with adverse effects, such as cataract and increased intraocular pressure. Further, systemic agents (particularly hypoglycemic, hypolipidemic, and antihypertensive agents) and plants-based drugs have also provided promising treatment in the progression of DR. Recently, advancements in pluripotent stem cells technology enable restoration of retinal functionalities after transplantation of these cells into animals with retinal degeneration. This review paper summarizes the developments in the current and potential pharmacotherapy and therapeutic technology of DR. Literature search was done on online databases, PubMed, Google Scholar, clinitrials.gov, and browsing through individual ophthalmology journals and leading pharmaceutical company websites.

Evolutionary triangulation: informing genetic association studies with evolutionary evidence

Genetic studies of human diseases have identified many variants associated with pathogenesis and severity. However, most studies have used only statistical association to assess putative relationships to disease, and ignored other factors for evaluation. For example, evolution is a factor that has shaped disease risk, changing allele frequencies as human populations migrated into and inhabited new environments. Since many common variants differ among populations in frequency, as does disease prevalence, we hypothesized that patterns of disease and population structure, taken together, will inform association studies. Thus, the population distributions of allelic risk variants should reflect the distributions of their associated diseases. Evolutionary Triangulation (ET) exploits this evolutionary differentiation by comparing population structure among three populations with variable patterns of disease prevalence. By selecting populations based on patterns where two have similar rates of disease that differ substantially from a third, we performed a proof of principle analysis for this method. We examined three disease phenotypes, lactase persistence, melanoma, and Type 2 diabetes mellitus. We show that for lactase persistence, a phenotype with a simple genetic architecture, ET identifies the key gene, lactase. For melanoma, ET identifies several genes associated with this disease and/or phenotypes related to it, such as skin color genes. ET was less obviously successful for Type 2 diabetes mellitus, perhaps because of the small effect sizes in known risk loci and recent environmental changes that have altered disease risk. Alternatively, ET may have revealed new genes involved in conferring disease risk for diabetes that did not meet nominal GWAS significance thresholds. We also compared ET to another method used to filter for phenotype associated genes, population branch statistic (PBS), and show that ET performs better in identifying genes known to associate with diseases appropriately distributed among populations. Our results indicate that ET can filter association results to improve our ability to discover disease loci.

A common functional variant on the pro-inflammatory Interleukin-6 gene may modify the association between long-term PM10 exposure and diabetes

BACKGROUND

Air pollutants have been linked to type 2 diabetes (T2D), hypothesized to act through inflammatory pathways and may induce interleukin-6 gene (IL6) in the airway epithelium. The cytokine interleukin-6 may impact on glucose homeostasis. Recent meta-analyses showed the common polymorphisms, IL6 -572G > C and IL6 -174G > C to be associated with T2D risk. These IL6 variants also influence circulatory interleukin-6 levels. We hypothesize that these common functional variants may modify the association between air pollutants and T2D.

METHODS

We cross-sectionally studied 4410 first follow-up participants of the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases (SAPALDIA), aged 29 to 73 years who had complete data on genotypes, diabetes status and covariates. We defined diabetes as self-reported physician-diagnosed, or use of diabetes medication or non-fasting glucose >11.1 mmol/L or HbA1c > 0.065. Air pollution exposure was 10-year mean particulate matter <10 μm in diameter (PM10) assigned to participants' residences using a combination of dispersion modelling, annual trends at monitoring stations and residential history. We derived interaction terms between PM10 and genotypes, and applied mixed logistic models to explore genetic interactions by IL6 polymorphisms on the odds of diabetes.

RESULTS

There were 252 diabetes cases. Respective minor allele frequencies of IL6 -572G > C and IL6 -174G > C were 7 and 39 %. Mean exposure to PM10 was 22 μg/m(3). Both variants were not associated with diabetes in our study. We observed a significant positive association between PM10 and diabetes among homozygous carriers of the pro-inflammatory major G-allele of IL6 -572G > C [Odds ratio: 1.53; 95 % confidence interval (1.22, 1.92); P interaction (additive) = 0.003 and P interaction (recessive) = 0.006]. Carriers of the major G-allele of IL6 -174G > C also had significantly increased odds of diabetes, but interactions were statistically non-significant.

CONCLUSIONS

Our results on the interaction of PM10 with functionally well described polymorphisms in an important pro-inflammatory candidate gene are consistent with the hypothesis that air pollutants impact on T2D through inflammatory pathways. Our findings, if confirmed, are of high public health relevance considering the ubiquity of the major G allele, which puts a substantial proportion of the population at risk for the development of diabetes as a result of long-term exposure to air pollution.

Association of TGFB1 29C/T and IL6 -572G/C polymorphisms with developmental hip dysplasia: a case-control study in adults with severe osteoarthritis

PURPOSE

Developmental dysplasia of the hip (DDH) increases the risk of severe adult hip osteoarthritis (OA). Transforming growth factor-β1 (TGF-beta1) and interleukin-6 (IL-6) are included in pathogenesis of OA, as well as in development of the musculoskeletal system. We investigated the association of single nucleotide polymorphisms (SNPs) known to reflect on the circulating levels of the two cytokines, specifically, 29 T → C transition in the TGFB1 signal sequence (rs1800470) and -572G → C transversion in the IL6 promoter (rs1800796), with DDH.

METHODS

We conducted a case-control study in consecutive unrelated adults with severe hip OA scheduled for total hip arthroplasty. Cases, patients with OA secondary to DDH (n = 68) and controls, patients with OA unrelated to DDH (n = 152) were genotyped at the two loci.

RESULTS

With adjustment for age, sex and genotype at the concurrent locus, cases were more likely (OR = 2.42, 95%CI 1.08-5.43; p = 0.032) to be transition homozygous at TGFB1 locus 29, and also more likely (OR = 6.36, 95%CI 2.57-15.7; p < 0.001) to be transversion homozygous at IL6 locus -572 than controls. Cases were also more likely (OR = 11.3, 95%CI 4.25-29.8; p < 0.001) than controls to carry one of the three genotypes combining transition/transversion homozygosity at both loci, or transition/transversion homozygosity at one and heterozygosity at the concurrent locus.

CONCLUSIONS

Data suggest association between TGFB1 29 T → C transition (rs1800470) and IL6 -572G → C transversion (rs1800796) with DDH, and also a possibility of TGF-beta1 and IL-6 interaction in DDH pathogenesis.

Lack of association between a functional polymorphism (rs1800796) in the interleukin-6 gene promoter and lung cancer

Background

A number of studies have examined the association between interleukin-6 (IL-6) rs1800796 polymorphism and risk of lung cancer but revealed inconsistent results. The aim of this study was to clarify the association between IL-6 rs1800796 polymorphism and risk of lung cancer.

Methods

Literature databases including PubMed, Embase and CNKI were searched up to January 2014. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) under co-dominant model, dominant model and recessive model were estimated using random-effects model.

Results

A total of seven studies, including 2691 lung cancer cases and 3067 controls, were included in the meta-analysis. The results suggested that IL-6 rs1800796 polymorphism was not associated with risk of lung cancer under homogeneous co-dominant model (OR = 1.06, 95%CI = 0.73-1.54), heterogeneous co-dominant model (OR = 1.24, 95%CI = 0.96-1.60), dominant model (OR = 1.23, 95%CI = 0.95-1.58) and recessive model (OR = 0.96, 95%CI = 0.70-1.32). The association was still not significant in either never-smokers (OR = 1.19, 95%CI = 0.95-1.48) or ever-smokers (OR = 1.73, 95%CI = 0.89-3.36).

Conclusion

The present meta-analysis suggested that there was no association between IL-6 rs1800796 polymorphism and lung cancer, which was independent of smoking status.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1060061508127855