Association between IL-6 gene polymorphisms and susceptibility of tuberculosis: evidence based on a meta-analysis

The present study aimed to investigate the association of IL-6 gene polymorphisms with tuberculosis (TB) susceptibility. There were inconsistent findings from previous studies on this topic. The aim of this study was to perform a meta-analysis to investigate the relationship between IL-6 -174G/C, G/A nt565 and -572C/G polymorphisms and TB risk. PubMed and Embase databases were searched for publications until September 2016 for eligible studies on IL-6 gene polymorphisms. The data from relevant studies were extracted and used to calculate pooled odd ratios (ORs) and 95% confidence intervals (95% CI). A total of 8 studies were included in this meta-analysis. There was a significant association between IL-6 -174G/C polymorphism and TB risk in the total population (CC vs GG: OR=0.67, 95% CI=0.43-1.05; CG vs GG: OR=0.72, 95% CI=0.57-0.90; Dominant model: OR=0.71, 95% CI=0.57-0.88; Recessive model: OR=0.77, 95% CI=0.50-1.19). In the subgroup analysis by ethnicity, the IL-6 -174G/C polymorphism was associated with TB risk in Asians. No association was found for IL-6 G/A nt565 polymorphism. For the IL-6 572C/G polymorphism, a significant correlation with TB risk was determined (GG vs CC: OR=0.84, 95% CI=0.25-2.84; GC vs CC: OR=0.71, 95% CI=0.55-0.90; Dominant model: OR=0.70, 95% CI=0.55-0.88; Recessive model: OR=0.96, 95% CI=0.26-3.56). In conclusion, the meta-analysis results suggest that IL-6 -174G/C and -572C/G polymorphisms might be associated with the risk of TB. No significant association was observed between the IL-6 G/A nt565 polymorphism and TB risk.