Effect of G(-174)C polymorphism in interleukin-6 gene on cardiovascular disease in type 2 diabetes patients

Study of the rs1800795 polymorphism of the <i>IL6</i> gene to verify the clinical portrait of a patient with chronic heart failure: gender aspects

Background. Genetic studies in cardiology allow to identify predisposition and predict the course of multifactorial cardiovascular diseases by identifying the association of polymorphic loci of candidate genes with the clinical phenotype. One of these diseases associated with poor prognosis is chronic heart failure (CHF). Activation of pro-inflammatory cytokines is one of the key aspects of the development and progression of CHF. Aim. To identify the features of the clinical course of CHF of ischemic etiology in patients, taking into account the gender and genotype of the rs1800795 polymorphism of the IL6 gene. Materials and methods. Four hundred fourteen patients of both sexes with stable CHF of ischemic origin, aged 66.410.4 years, were included. Clinical characteristics of men and women of each genotype of the rs1800795 polymorphism of the IL6 gene were compared. Genotyping of the rs1800795 polymorphism of the IL6 gene was performed by real-time polymerase chain reaction. Results. In male patients with CHF, the frequency of allele C was higher than in the control group (p=0.04). Homozygous carriers of the C allele showed a greater risk of developing atrial fibrillation (p=0.021). In terms of biochemical parameters, in patients with a heterozygous genotype, compared with homozygotes for the G allele of the rs1800795 polymorphism of the IL6 gene, the levels of cholesterol, triglycerides (TG), cholesterol not associated with high-density lipoproteins (non-HDL-cholesterol) were higher (p=0.044, p=0.019, p=0.016). Patients with the CC genotype of the rs1800795 polymorphism of the IL6 gene females compared with men were more likely to have IIIIV functional class of CHF (p=0.001) and had a high heart rate (p=0.021). Male patients of the CG genotype were more likely to undergo coronary interventions (p=0.001). In women of the CG genotype, CHF was more often combined with DM (p=0.015), the level of non-HDL-cholesterol (p=0.04) was higher, and glomerular filtration rate was lower than in men (p=0.001). Comparison of the GG genotype revealed a higher incidence of chronic kidney disease in women (p=0.022). Women had significantly lower glomerular filtration rate (p=0.001), systolic blood pressure (p=0.004). The level of such biochemical parameters as cholesterol (p=0.001), TG (p=0.019), low-density lipoprotein cholesterol (p=0.002) was reduced, except for high non-HDL-cholesterol (p=0.001). There were more men with left ventricular ejection fraction 40% (p=0.009), women with left ventricular ejection fraction 50% (p=0.002). Conclusion. The identified phenotypic and gender differences create prerequisites for determining patient-oriented genetic risk, opening up new opportunities for preventing the progression and complications of CHF.

IL-6 gene rs1800795 polymorphism and diabetes mellitus: a comprehensive analysis involving 42,150 participants from a meta-analysis

BACKGROUND

Over the past two decades, several studies have focused on the association between a common polymorphism (rs1800795) from interleukin-6 (IL-6) gene and Diabetes Mellitus (DM) risk. However, the results remain ambiguous and indefinite.

METHODS

A comprehensive analysis was performed to explore this relationship. A search was conducted in the PubMed, Embase, Chinese (CNKI and Wanfang), and GWAS Catalog databases, covering all publications until February 10, 2022. Odds ratios (OR) with 95% confidence intervals (CI) were used to evaluate the strength of the association. Publication bias was assessed using both Begg and Egger tests.

RESULTS

Overall, 34 case-control studies with 7257 T2DM patients and 15,598 controls, and 12 case-control studies (10,264 T1DM patients and 9031 health controls) were included in the analysis. A significantly lower association was observed between the rs1800795 polymorphism and T2DM risk in Asians, mixed population, and hospital-based (HB) subgroups (C-allele vs. G-allele: OR = 0.76, 95% CI  0.58-0.99, P = 0.039 for Asians; CG vs. GG: OR = 0.74, 95% CI  0.58-0.94, P = 0.014 for mixed population; CC vs. GG: OR = 0.61, 95% CI  0.41-0.90, P = 0.014 for HB). However, increased associations were found from total, mixed population, and HB subgroups between rs1800795 polymorphism and T1DM susceptibility (CG vs. GG: OR = 1.32, 95% CI 1.01-1.74, P = 0.043 for total population, CC vs. GG: OR = 2.45, 95% CI 1.18-5.07, P = 0.016 for mixed individuals; C-allele vs. G-allele: OR = 1.29, 95% CI 1.07-1.56, P = 0.0009 for HB subgroup).

CONCLUSIONS

In summary, there is definite evidence to confirm that IL-6 rs1800795 polymorphism is associated with susceptibility to decreased T2DM and increased T1DM.

Meta-analysis: Interleukin 6 gene -174G/C polymorphism associated with type 2 diabetes mellitus and interleukin 6 changes

The gene coding interleukin 6 (IL‐6) is a promising candidate in predisposition to type 2 diabetes mellitus (T2DM). This study aimed to meta‐analytically examine the association of IL‐6 gene −174G/C polymorphism with T2DM and circulating IL‐6 changes across −174G/C genotypes. Odds ratio (OR) and standard mean difference (SMD) with 95% confidence interval (CI) were calculated. Twenty‐five articles were meta‐analysed, with 20 articles for T2DM risk and 9 articles for circulating IL‐6 changes. Overall, there was no detectable significance for the association between −174G/C polymorphism and T2DM, and this association was relatively obvious under dominant model (OR: 0.82, 95% CI: 0.56‐1.21). Improved heterogeneity was seen in some subgroups, with statistical significance found in studies involving subjects of mixed races (OR: 0.63, 95% CI: 0.46‐0.86). Begg's and filled funnel plots, along with Egger's tests revealed week evidence of publication bias. In genotype‐phenotype analyses, carriers of −174CC and −174CG genotypes separately had 0.10 and 0.03 lower concentrations (pg/mL) of circulating IL‐6 than −174GG carriers. Albeit no detectable significance for the association of −174G/C with T2DM, our findings provided suggestive evidence on a dose‐dependent relation between −174G/C mutant alleles and circulating IL‐6 concentrations, indicating possible implication of this polymorphism in the pathogenesis of T2DM.

Non-pharmacological Strategies Against Systemic Inflammation: Molecular Basis and Clinical Evidence

Systemic inflammation is a common denominator to a variety of cardiovascular (CV) and non-CV diseases and relative risk factors, including hypertension and its control, metabolic diseases, rheumatic disorders, and those affecting the gastrointestinal tract. Besides medications, a non-pharmacological approach encompassing lifestyle changes and other complementary measures is mentioned in several updated guidelines on the management of these conditions. We performed an updated narrative review on the mechanisms behind the systemic impact of inflammation and the role of non-pharmacological, complementary measures centered on lowering systemic phlogosis for preserving or restoring a good global health. The central role of genetics in shaping the immune response is discussed in conjunction with that of the microbiome, highlighting the interdependence and mutual influences between the human genome and microbial integrity, diversity, and functions. Several plausible strategies to modulate inflammation and restore balanced crosstalk between the human genome and the microbiome are then recapitulated, including dietary measures, active lifestyle, and other potential approaches to manipulate the resident microbial community. To date, evidence from high-quality human studies is sparse to allow the unconditioned inclusion of understudied, though plausible solutions against inflammation into public health strategies for global wellness. This gap claims further focused, well-designed research targeted at unravelling the mechanisms behind future personalized medicine.

Interleukin 6 (rs1800795) gene polymorphism is associated with cardiovascular diseases: a meta-analysis of 74 studies with 86,229 subjects

Cardiovascular diseases (CVD) are group of complex and multifactorial pathologies, in which interleukin-6 (IL-6) gene polymorphisms have been associated with several components of the CVD. Thus, in this study, we thoroughly reviewed and meta-analyzed evidence on the association between the IL-6 (rs1800795) gene polymorphism and CVD. We systematically searched in the PubMed, Web of Sciences, and Scopus databases. The analyses were performed using five study groups based on (1) a combined pool of the overall populations, (2) the country of birth, (3) the continent of birth, (4) the diagnosis and (5) both location (country or continent) and diagnosis. The analysis included the allelic, homozygote, heterozygote, dominant and recessive models. The meta-analysis showed that -174G>C (rs1800795) is a risk factor for CVD (allelic: OR=1.06, CI 95%=1.02-1.10. Z p value <0.0001; homozygous: OR=1.11, CI 95%=1.03-1.19, Z p value= 0.002; heterozygous: OR=1.08, CI 95%=1.03-1.21, Z p value= 0.003; dominant: OR= 1.12, CI 95%= 1.07-1.18, Z p value= 0.001) and that this risk increases in the Chinese population. Additionally, we found that carriers of the C allele of 174G>C (rs1800795) polymorphism have an increase in the risk of coronary artery disease under the hereditary models assessed in the study. Using robust data, we found that IL-6 (rs1800795) -174G>C gene polymorphism is associated with CVD risk.

Association of the Interleukin-6 rs1800795 Polymorphism with Type 2 Diabetes Mellitus in the Population of the Island of Crete, Greece

BACKGROUND

Interleukin 6 (IL-6), a proinflammatory cytokine, is elevated in patients with type 2 diabetes (T2D), and is considered an independent predictor of T2D. IL-6 single-nucleotide polymorphisms (SNPs) have been associated with higher levels of IL-6. This study investigated the role of an IL-6 gene polymorphism and its possible association to T2D in the genetically homogeneous Greek population of the island of Crete.

MATERIALS AND METHODS

A total of 144 patients with T2D and 180 controls, all Cretans, selected from the Diabetes Clinic and the Department of Internal Medicine at the University Hospital of Heraklion, Crete, Greece, were genotyped for the IL-6 -174G>C (rs1800795) SNP by the restriction fragment length polymorphism method.

RESULTS

The G/C genotype and the minor allele C of the IL-6 rs1800795 SNP were more common in individuals with T2D than controls (p = 0.004, odds ratio [OR] = 1.98, 95% confidence interval [CI]: 1.24-3.18 and p = 0.011, OR = 1.59, 95% CI: 1.11-2.26, respectively).

CONCLUSION

An association of the rs1800795 SNP of the IL-6 gene with T2D has been detected for the first time in Cretans. The present results, in combination with those presented previously from different ethnic/racial populations, highlight the necessity of comparative studies among different ethnic/racial populations to detect genetic characteristics and associations with T2D.

Association of Interleukin-6 Genetic Polymorphisms and Environment Factors Interactions with Coronary Artery Disease in a Chinese Han Population

OBJECTIVES

To investigate the influence of IL-6 single nucleotide polymorphisms (SNPs), additional gene-gene and gene-environment interactions on coronary artery disease (CAD) risk.

METHODS

A total of 751 participants (429 CAD patients and 322 controls) were recruited in this study. Logistic regression analysis was conducted to evaluate the association of IL-6 SNPs with CAD risk and generalized multifactor dimensionality reduction (GMDR) was performed to investigate the best interaction combinations for gene-gene and gene-environment interactions.

RESULTS

CAD risk is significantly higher in carriers of C allele of the rs1800795 polymorphism than those with GG genotype (CC + CG versus GG, adjusted OR (95%CI) = 2.07 (1.56-2.86), p < 0.001). GMDR analysis revealed rs1800795 was significantly interacted with tobacco smoking and alcohol drinking in two-locus model (p < 0.0010). Current smokers with CC or CG of rs1800795 genotype have the highest CAD risk, OR (95%CI) = 3.22 (2.45-3.94) and current drinkers with CC or CG of rs1800795 genotype have the highest CAD risk, OR (95%CI) = 3.17 (2.20-4.24).

CONCLUSION

The C allele of rs1800795 within IL-6 gene promoter, rs1800795-tobacco smoking and rs1800795-alcohol drinking interaction were all associated with increased CAD risk.

Dual Effect of IL-6 -174 G/C Polymorphism and Promoter Methylation in the Risk of Coronary Artery Disease Among South Indians

Inflammation plays an important role in the pathogenesis of atherosclerosis and coronary syndromes; moreover, various lines of evidence suggest that genetic factors do contribute to the risk of coronary artery disease (CAD). The proinflammatory cytokine IL-6 is a central mediator of inflammation associated with CAD. The present study is aimed to investigate the association of single nucleotide polymorphism in the promoter region of the IL-6 gene (-174 G > C) and methylation with the susceptibility of CAD. Genotyping of IL-6 -174 G/C polymorphism was performed by PCR-RFLP. Methylation-specific PCR method was used to study the IL-6 gene promoter methylation. Analysis of 470 subjects (265 CAD patients and 205 controls) showed association of the -174 G/C variant with the CAD risk in dominant model (OR 1.58, 95% CI, 1.024-2.23, P = 0.04). Further, the analysis of the distribution of genotypes and alleles of -174 G > C polymorphism according to clinical features of CAD, revealed significant association of genotype and allele (OR 1.86, 95% CI 1.18-2.84 P = 0.01, and OR 1.71, 95% CI 1.09-2.23 P = 0.02 respectively) with diabetes, and we found no association with hypertension (OR 0.95, 95% CI 0.57-1.59, P = 0.8). We also analyzed the methylation status of IL-6 promoter region between cases and controls showed significant hypo methylation in CAD subjects (OR 2.36, 95% CI 1.51-4.259, P = 0.006). Additionally, GC, CC genotypes and C allele carriers show hypomethylation in CAD cases compared to controls (54.58 vs. 76.85%, 29.83 vs. 40% respectively). In conclusion, the promoter polymorphism -174 G/C is associated with CAD risk and further carriers of 'C' allele at -174 locus showed significant hypo methylation which could contribute to increased risk of CAD. The present study highlights the association of allele and genotypes with differential DNA methylation of CpG islands in the IL-6 promoter region which may affect IL-6 gene regulation.

Glycated hemoglobin level is an independent predictor of major adverse cardiac events after nonfatal acute myocardial infarction in nondiabetic patients: A retrospective observational study

The effect of glycemic control on the prognosis of nondiabetic patients after acute myocardial infarction (AMI) remains uncertain. We investigated whether glycated hemoglobin (HbA1c) is associated with adverse outcomes after AMI in nondiabetic patients. In this observational study, we enrolled nondiabetic patients with AMI in the emergency department of 2 medical centers from January 2011 to September 2014. All patients received primary percutaneous coronary intervention and were divided into 4 groups according to the interquartile range of average HbA1c level (Group I, ≤5.6%; Group II, 5.6%-5.8%; Group III, 5.8%-6.0%; and Group IV, >6.0%). Multivariate logistic analysis was performed to estimate the correlation of HbA1c with major adverse cardiac events (MACEs) after AMI. In total, 267 eligible patients were enrolled; 48 patients (18%) developed MACEs within a median follow-up of 178 days. Univariate analysis showed HbA1c > 6.0%, with a higher risk of MACEs in Group IV than in Group I (odds ratio [OR]: 2.733; 95% confidence interval [CI]: 1.123-6.651 vs OR: 1.511; 95% CI: 0.595-3.835). Multivariate analysis revealed an approximately 3.8 times higher risk of MACEs in Group IV than in Group I (OR: 3.769; 95% CI: 1.30-10.86). The HbA1 level is a significant predictor of MACEs after AMI in nondiabetic patients.

Susceptibility to chronic inflammation: an update

Chronic inflammation is defined by the persistence of inflammatory processes beyond their physiological function, resulting in tissue destruction. Chronic inflammation is implicated in the progression of many chronic diseases and plays a central role in chronic inflammatory and autoimmune disease. As such, this review aims to collate some of the latest research in relation to genetic and environmental susceptibilities to chronic inflammation. In the genetic section, we discuss some of the updates in cytokine research and current treatments that are being developed. We also discuss newly identified canonical and non-canonical genes associated with chronic inflammation. In the environmental section, we highlight some of the latest updates and evidence in relation to the role that infection, diet and stress play in promoting inflammation. The aim of this review is to provide an overview of the latest research to build on our current understanding of chronic inflammation. It highlights the complexity associated with chronic inflammation, as well as provides insights into potential new targets for therapies that could be used to treat chronic inflammation and consequently prevent disease progression.

Promoter Polymorphism (-174, G/C) of Interleukin-6 and Arterial Thromboembolic Events: A Meta-Analysis

Background

Ischemic stroke and myocardial infarction are fatal diseases and are among the top 10 causes of death in Korea, including arterial thromboembolic events. Many previous studies have described the function of interleukin-6 (IL-6) in arterial thromboembolic events and the association between promoter single-nucleotide polymorphism (SNP) (rs1800795; −174, G/C) of the IL-6 gene. However, these results were controversial. Therefore, we performed a meta-analysis to more precisely assess the association between the SNP of the IL-6 gene and susceptibility to arterial thromboembolic events.

Material/Methods

We used PubMed, Embase, Google Scholar, and Korean Studies Information Service System (KISS) electronic databases. Comprehensive Meta-analysis software (Corporation, NJ) was used to evaluate the relationship between rs1800795 SNP of IL-6 gene and risk of arterial thromboembolic events. Odds ratio (OR), 95% confidence interval (CI), and P value were also calculated. The 13 eligible studies were analyzed in the meta-analysis.

Results

The present meta-analysis found that rs1800795 SNP of IL-6 gene is not significantly associated with susceptibility to arterial thromboembolic events (C allele vs. G allele, OR=1.04, 95% CI=0.91–1.19, P=0.619; CC vs. CG+GG, OR=1.09, 95% CI=0.91–1.31, P=0.364; CC+CG vs. GG, OR=0.97, 95% CI=0.78–1.21, P=0.763, respectively), and the SNP of IL-6 gene also did not show any significant association with ischemic stroke or myocardial infarction (P>0.05 in each model).

Conclusions

We found that rs1800795 SNP of IL-6 gene was not related to arterial thromboembolic events. However, further study will be needed to confirm these results.

Interleukin-6 polymorphisms and risk of coronary artery diseases in a Chinese population: A case-control study

Objective:

We aimed to evaluate the relationship between IL-6-174G>C, -572G>C and -597G>A polymorphisms and development of coronary artery diseases in a Chinese population.

Methods:

A total of 275 patients with coronary artery disease and 296 healthy control subjects were collected between January 2013 and November 2014. The IL-6 genotyping for -174G>C, -592G>C and -597G>A polymorphic sites was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) according to the manufacturer instructions.

Results:

Using unconditional regression analysis, we observed that the AC and CC genotypes of IL-6 -592A>C were associated with the increased risk of developing coronary artery disease when compared with the AA genotype, and the adjusted ORs (95%CI) were 1.63(1.12-2.38) and 2.70(1.57-4.67), respectively. Additionally, the C allele of IL-6 -592A>C (OR=1.65, 95%CI=1.29-2.11) was correlated with a higher risk of developing coronary artery disease in comparison to the A allele. However, no relationship was found between IL-6-174G>C and -597G>A polymorphisms and coronary artery disease susceptibility.

Conclusion:

This study suggests that IL-6 -592G>C polymorphism is correlated with the risk of coronary artery disease. More well-designed prospective studies based on large sample size, multiple SNPs or haplotypes are required to confirm the current findings.