Abstract
BackgroundA large number of studies have investigated whether polymorphisms in the Toll-like receptor (TLR) genes are implicated in susceptibility to tuberculosis (TB) in different populations. However, the results are inconsistent and inconclusive.MethodsA literature search was conducted using the PubMed, EMBASE, Medline (Ovid), ISI Web of Knowledge and Chinese National Knowledge Infrastructure (CNKI). A meta-analysis on the associations between the TLR1 G1805T, TLR2 T597C, T1350C, G2258A, and TLR6 C745T polymorphisms and TB risk was carried out by comparison using different genetic models.ResultsIn total, 16 studies from 14 articles were included in this review. In meta-analysis, significant associations were observed between the TLR2 2258AA (AA vs. AG+AG, OR 5.82, 95% CI 1.30–26.16, P = 0.02) and TLR6 745TT (TT vs. CT+CC, OR 0.61, 95% CI 0.39–0.97, P = 0.04) polymorphisms and TB risk. In the subgroup analysis by ethnicity, Africans and American Hispanic subjects with the TLR1 1805T allele had an increased susceptibility, whereas Asian and European subjects with the TLR2 2258A allele had an increased susceptibility to TB.ConclusionsThe meta-analysis indicated that TLR2 G2258A is associated with increased TB risk, especially in Asians and Europeans. TLR1 G1805T is associated with increased TB in Africans and American Hispanics. TLR6 C745T is associated with decreased TB risk. Our systematic review and meta-analysis reported an interesting preliminary conclusion, but this must be validated by future large-scale and functional studies in different populations.
Highlights
Tuberculosis (TB) is a contagious and potentially fatal disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis (Mtb) in humans
We performed a meta-analysis to assess the association between five extensively studied polymorphisms (TLR1 G1805T, TLR2 T597C, T1350C, G2258A and TLR6 C745T) and TB risk reported until 1st January 2013
TLR1 1805T allele was associated with TB in Africans and American Hispanics, and TLR2 2258A allele was associated with TB in Asians and Europeans
Summary
Tuberculosis (TB) is a contagious and potentially fatal disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis (Mtb) in humans. It can infect almost any part of the body, but manifests mainly as an infection of the lungs and kills more people each year than any other single infectious disease. It is estimated by WHO that about one-third of the current global population is infected asymptomatically with Mtb, of whom 5–10% will develop clinical disease during their lifetime [1] This fact together with other substantial evidence indicates that variations in host hereditary factors play an important role in susceptibility to TB [2].
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