Systematic review and meta-analysis of association of polymorphisms in inflammatory cytokine genes with coronary artery disease

The Potential of Single Nucleotide Polymorphisms (SNPs) as Biomarkers and Their Association with the Increased Risk of Coronary Heart Disease: A Systematic Review

Human genetic analyses and epidemiological studies showed a potential association between several types of gene polymorphism and the development of coronary heart disease (CHD). Many studies on this pertinent topic need to be investigated further to reach an evidence-based conclusion. Therefore, in this current review, we describe several types of gene polymorphisms that are potentially linked to CHD. A systematic review using the databases EBSCO, PubMed, and ScienceDirect databases was searched until October of 2022 to find relevant studies on the topic of gene polymorphisms on risk factors for CHD, especially for the factors associated with single nucleotide polymorphisms (SNPs). The risk of bias and quality assessment was evaluated by Joanna Briggs Institute (JBI) guidelines. From keyword search results, a total of 6243 articles were identified, which were subsequently narrowed to 14 articles using prespecified inclusion criteria. The results suggested that there were 33 single nucleotide polymorphisms (SNPs) that can potentially increase the risk factors and clinical symptoms of CHD. This study also indicated that gene polymorphisms had a potential role in increasing CHD risk factors that were causally associated with atherosclerosis, increased homocysteine, immune/inflammatory response, Low-Density Lipoprotein (LDL), arterial lesions, and reduction of therapeutic effectiveness. In conclusion, the findings of this study indicate that SNPs may increase risk factors for CHD and SNPs show different effects between individuals. This demonstrates that knowledge of SNPs on CHD risk factors can be used to develop biomarkers for diagnostics and therapeutic response prediction to decide successful therapy and become the basis for defining personalized medicine in future.

A comprehensive meta-analysis comprising 149 case-control studies to investigate the association between IL-6 gene rs1800795 polymorphism and multiple disease risk

BACKGROUND

Individual genome-wide association studies (GWAS) or single case-specific meta-analyses may not be sufficient evidence to take action against a specific gene function. Thus, we tried to determine a consensus association between the IL-6 gene rs1800795 polymorphism and multiple disease risks through an updated statistical meta-analysis.

METHOD

After systematically searching online databases, we found 149 case-control relevant datasets with a sample size of 96,153 (cases: 38,291 and controls: 57862) and conducted the meta-analysis using updated statistical models.

RESULTS

The analyses of this comprehensive meta-analysis revealed a significant association between IL-6 -174G/C polymorphism and overall disorder risk under all genetic models (C vs G: OR = 1.11, 95% CI = 1.08-1.13; p-value = 4.8E-17; CC vs GG: OR = 1.19, 95% CI = 1.13-1.26; p-value = 9.4E-12; CG vs GG: OR = 1.10, 95% CI = 1.06-1.14; p-value = 1.1E-07; CC + CG vs GG: OR = 1.13, 95% CI = 1.10-1.17; p-value = 1.1E-13; CC vs CG + GG: OR = 1.18, 95% CI = 1.06-1.31; p-value = 0.0019) and (OR > 1) with Asian ethnicity. The subgroup analyses based on the diseases revealed that the polymorphism was highly significantly increasing the risk of coronary artery disease (CAD) under all genetic models. Likewise, a significant association was observed with increased risk under three genetic models of inflammatory diseases (C vs G; CC vs GG; and CC vs CG + GG), and rheumatoid arthritis (C vs G; CG vs GG; and CC + CG vs GG). Conversely, the -174G/C SNP significantly decreased the risk of ischemic stroke under the two genetic models (C vs G; and CG vs GG). However, the other diseases included in this study showed no significant association with IL-6 (-174G/C) polymorphism.

CONCLUSION

This meta-analysis provided strong evidence for the association between IL-6 gene rs1800795 polymorphism and multiple disease risks. The IL-6 gene could be a useful prognostic biomarker for CAD, inflammatory disease, ischemic stroke, and rheumatoid arthritis.

Association of interleukin 6 -174 G/C polymorphism with coronary artery disease and circulating IL-6 levels: a systematic review and meta-analysis

INTRODUCTION

Circulating IL-6 levels and at least one polymorphic form of IL6 gene (IL6 -174 G/C, rs1800795) have been shown to be independently associated with coronary artery disease (CAD) by several investigators. Despite more than 12 published meta-analyses on this subject, association of -174 G/C with CAD, especially amongst distinct ancestral population groups remain unclear. We, therefore, conducted a systematic review and an updated meta-analysis to comprehensively ascertain the association of IL6 -174 G/C with CAD and circulating IL-6 levels.

MATERIALS AND METHODS

Relevant case-control/cohort studies investigating association of -174 G/C with CAD and circulating IL-6 levels were identified following a comprehensive online search. Association status for CAD was determined for the pooled sample, as well as separately for major ancestral subgroups. Association status for circulating IL-6 levels was assessed for the pooled sample, as well as separately for CAD cases and CAD free controls. Study-level odds ratios (OR) and 95% confidence intervals (CI) were pooled using random/fixed-effects model.

RESULTS

Quantitative synthesis for the CAD endpoint was performed using 55 separate qualifying studies with a collective sample size of 51,213 (19,160 cases/32,053 controls). Pooled association of -174 G/C with CAD was found to be statistically significant through dominant (OR 1.15; 95% CI 1.05-1.25, p = 0.002) as well as allelic genetic model comparisons (OR 1.13, 95% CI 1.06-1.21, p = 0.0003). This effect was largely driven by Asian and Asian Indian ancestral subgroups, which also showed significant association with CAD in both genetic model comparisons (OR range 1.29-1.53, p value range ≤ 0.02). Other ancestral subgroups failed to show any meaningful association. Circulating IL-6 levels were found to be significantly higher amongst the 'C' allele carriers in the pooled sample (Standard mean difference, SMD 0.11, 95% CI 0.01-0.22 pg/ml, p = 0.009) as well as in the CAD free control subgroup (SMD 0.10, 95% CI 0.02-0.17 pg/ml, p = 0.009), though not in the CAD case subgroup (SMD 0.17, 95% CI = - 0.02 to 0.37, p = 0.12).

CONCLUSIONS

The present systematic review and meta-analysis demonstrate an overall association between IL6 -174 G/C polymorphism and CAD, which seems to be mainly driven by Asian and Asian Indian ancestral subgroups. Upregulation of plasma IL-6 levels in the 'C' allele carriers seems to be at least partly responsible for this observed association. This warrants further investigations with large, structured case-control studies especially amongst Asian and Asian Indian ancestral groups.

APOE gene ɛ4 allele (388C-526C) effects on serum lipids and risk of coronary artery disease in southern Chinese Hakka population

OBJECTIVE

To analyze the relationship of Apolipoprotein E (APOE) and solute carrier organic anion transporter family member 1B1 (SLCO1B1) gene polymorphisms with coronary artery disease (CAD).

METHODS

1,129 CAD patients and 1,014 non-CAD controls were included in the study, and relevant information and medical records were collected. The single-nucleotide polymorphisms (SNPs) were analyzed, including rs429358, rs7412 in APOE gene and rs2306283, rs4149056 in SLCO1B1 gene.

RESULTS

The CAD patients' average age was 66.3 ± 10.7 years, while 65.5 ± 12.0 years in controls. The frequencies of APOE allele ɛ3, ɛ4, and ɛ2 were 83.01%, 10.08%, and 6.91% respectively. There were statistically significant differences in genotype ɛ3/ɛ4 (χ²  = 8.077, p = 0.005) in CAD patients compared with the controls. The SLCO1B1 genotype *1b/*1b and haplotype *1b showed the highest frequency in the study sample. Moreover, ε4 carriers had significantly lower HDL-C, Apo-A1 levels than ε3 carriers among CAD patients, while ε2 carriers showed lower LDL-C, Apo-B level, and higher Apo-A1/Apo-B level than ε3 and ε4 carriers. In controls, ε2 carriers showed lower LDL-C and Apo-B level, higher Apo-A1, and Apo-A1/Apo-B level than ε4 carriers. Logistic regression analysis showed that high LDL-C and Apo-B level, low HDL-C level, smoking, and the ε4 allele were risks for the presence of CAD.

CONCLUSIONS

APOE ε4 allele may be associated with susceptibility to CAD in southern Chinese Hakka population. It indicated that the APOE SNPs rs429358 and rs7412 are associated with CAD, but not SNPs rs2306283 and rs4149056 of SLCO1B1 gene.