CCL1, one of the members of the CC chemokine family, is an inflammatory mediator that stimulates the migration of human monocytes. CCL1 expression is induced by Mycobacterium tuberculosis and TLR ligands in macrophage. TLR2 plays critical role in host immune response against M. tuberculosis infection by regulating the macrophage activation and cytokine secretion. M. tuberculosis causes different clinical forms of tuberculosis (TB) disease. Single-nucleotide polymorphisms (SNPs) in the CCL1 gene and TLR2 gene may be associated with the development of different clinical forms of TB, depending on the different immune mechanisms. This study was to evaluate the possible association between CCL1 rs2072069 G/A or/and TLR2 rs3804099 T/C (T597C) polymorphisms and pulmonary tuberculosis (PTB) or/and tuberculous meningitis (TBM) in a sample of the Chinese adult population. A case-control study was designed to compare the allele frequency and genotype distribution between control (n=386) and TB (n=341) who had either PTB (n=230) or TBM (n=111). The genotype typing was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. TLR2 variant genotype 597CC was associated with susceptibility to PTB rather than to TBM. In the male PTB subgroup, 597CC genotype was identified in a higher rate, compared with male control subgroup. This study demonstrates that T597C polymorphism of TLR2 is a risk factor for susceptibility to PTB rather than to TBM in a sample of Chinese adult population. Patient gender may affect the outcome of M. tuberculosis infection. TLR2 gene may influence the development of PTB and TBM by different immune mechanisms.
Keywords: CCL1; TLR2; polymorphism; pulmonary tuberculosis (PTB); tuberculosis (TB); tuberculous meningitis (TBM).