Toll-like receptor and TIRAP gene polymorphisms in pulmonary tuberculosis patients of South India

Toll-like receptors (TLRs) are pattern recognition receptors and play an important role in innate immunity. Changes in TLRs and signaling molecules that result from polymorphisms are often associated with susceptibility to various infectious diseases. In the present study, we investigated whether variants in the TLR-1 1805T/G (Ile602Ser), TLR-2 2258G/A (Arg753Gln), TLR-4 896A/G (Asp299Gly), TLR-4 1196C/T (Thr399Ile), TLR-6 745C/T (Ser249Pro), TIRAP 975C/T (Ser180Leu) genes and TLR-9 promoter region polymorphisms at positions -1237C/T and -1486C/T are associated with susceptibility or resistance to pulmonary tuberculosis (PTB). Genotyping of TLR and TIRAP gene polymorphisms was performed by polymerase chain reaction followed by restriction fragment length polymorphism method in 212 healthy control subjects (HCs) and 206 PTB patients. The allele and genotype frequencies of various TLR genes were not different between the HCs and PTB patients. However, the study is underpowered to detect minor associations. The frequency of T allele of TIRAP 975C/T (Ser180Leu) polymorphism was significantly increased among PTB patients as compared to HCs [p = 0.026; Odds ratio (OR) 1.49, 95% Confidence interval (CI) 1.049-2.22]. A trend towards an increased frequency of TT genotype of TIRAP 975C/T was also observed in PTB patients [p = 0.078, OR 3.10 95% CI (0.96-10.05)]. The present study suggests that T allele of TIRAP 975C/T polymorphism may be associated with susceptibility to pulmonary TB in south Indian population. Further study on the regulatory role of this polymorphism may be helpful to understand the innate immunity in TB.