Toll-like Receptor Polymorphisms and Tuberculosis Susceptibility: A Comprehensive Meta-analysis

The polymorphisms of toll-like receptor (TLR) have been hypothesized to affect the tuberculosis susceptibility. However, the direct evidence remains controversial. Here we performed a comprehensive meta-analysis to summarize the associations between TLR polymorphisms and tuberculosis susceptibility. We systematically searched the PubMed, Embase, Cochrane library, and Chinese National Knowledge Infrastructure up to April 25, 2014. Case-control studies investigating TLR polymorphisms and tuberculosis susceptibility were included in the meta-analysis. Pooled odds ratios and corresponding 95% confidence intervals were calculated for cases and controls. Stata 11.0 and Review Manager 5.1 were adopted to conduct statistical analysis. We included 29 studies, involving 17 804 individuals. The results revealed an obvious increase of tuberculosis risk in TLR2 2258AA, and decreased risk in TLR6 745TT and TLR8 rs3761624 GA genotypes. Meanwhile, different genetic models were performed. TLR8 rs3764879C, TLR8 rs3761624A and TLR8 rs3764880A alleles were associated with high susceptibility, while TLR6 745T and TLR8 rs3788935C alleles were protective. Other polymorphisms, including TLR9 1486C/T, did not show significant associations with tuberculosis infection. Finally, subgroup analysis in TLR8 rs3764880 according to gender found a slight elevated effect of A allele in males. The meta-analysis suggests significant associations between several TLR polymorphisms and tuberculosis, including TLR2 2258G/A, TLR6 745C/T, TLR8 rs3761624, TLR8 rs3764879, TLR8 rs3761624 and TLR8 rs3764880. This study serves as the framework for additional studies to determine further the role of TLRs in tuberculosis infection.