IL-1β+3953C/T, -511T/C and IL-6 -174C/G polymorphisms in association with tuberculosis susceptibility: A meta-analysis.

Background: Studies of the association between the interleukin-1β gene (IL-1β) (+3953C/T, -511T/C) and interleukin-6 gene (IL-6) (-174G/C) polymorphisms and susceptibility to tuberculosis (TB) have yielded inconsistent results. The aim of this study was to investigate the relationship between these polymorphisms and TB risk by this meta-analysis.

Methods: We systematically searched published literatures on IL-1β gene and IL-6 gene polymorphisms and tuberculosis risk by the PubMed, Medline, Embase, Web of Science, Elsevier Science Direct and Cochrane Library databases, and identified outcome data from all articles. Statistical analysis was performed using Stata 12.0. A total of 15 studies comprising 3983TB patients and 3996 controls were included in the present study.

Results: We found that the IL-6 -174C/G polymorphism might be associated with decreased risk of TB (C vs. G: OR=0.77, 95% CI=0.64-0.91; CG vs. GG: OR=0.72, 95% CI=0.57-0.90; CC+CG vs. GG: OR=0.71, 95% CI=0.57-0.88). In the stratified analysis by ethnicity, significantly decreased risk were observed for IL-1β -511T/C polymorphism in Africans (C allele vs. T allele: OR=0.86, 95% CI=0.74-0.99; CC vs. TT: OR=0.74, 95% CI=0.55-0.99). Moreover, the IL-6 -174 C/G polymorphism was also associated with decreased risk of TB in Asians (C vs. G: OR=0.71, 95% CI=0.54-0.93; CG vs. GG: OR=0.61, 95% CI=0.44-0.85; CC+CG vs. GG: OR=0.63, 95% CI=0.46-0.86). We also performed the analyses by sample types in IL-6 -174 C/G polymorphism, and significant decreased TB risk was observed in pulmonary tuberculosis group (C allele vs. G allele: OR=0.69, 95% CI=0.52-0.93; CG vs. GG: OR=0.69, 95% CI=0.52-0.91; CC+CG vs. GG: OR=0.71, 95% CI=0.55-0.93), and pulmonary tuberculosis plus extra-pulmonary tuberculosis mixed group (CC vs. GG: OR=0.44, 95% CI=0.22-0.88; CC vs. CG+GG: OR=0.48, 95% CI=0.25-0.94).

Conclusions: This meta-analysis indicates that the IL-1β -511T/C polymorphism is associated with TB decreased risk in Africans, and IL-6 -174C/G polymorphism in Asians. Further well-designed, large scale studies are required to confirm this conclusion.