CCL5 (RANTES) gene polymorphisms in pulmonary tuberculosis patients of south India

The chemokine CCL5 is known to play an important role in the formation of granuloma during infection with Mycobacterium tuberculosis. Production of CCL5 is influenced by polymorphisms in the CCL5 gene. Hence, in the present study, we investigated whether polymorphisms in the promoter and intron regions of CCL5 gene are associated with susceptibility or resistance to pulmonary tuberculosis in south Indian population. Polymorphisms in the promoter (-403G/A and -28C/G) and intron (In1.1T/C) regions of CCL5 gene were studied in 212 pulmonary tuberculosis (PTB) patients and 213 healthy controls (HCs). Allele and genotype frequencies of CCL5 gene polymorphisms were not different between PTB patients and HCs. When the haplotype and diplotype frequencies were compared, a significantly decreased frequencies of the haplotype A-C-C [P = 0.037; Odds ratio (OR): 0.57; 95% confidence interval (CI): 0.34-0.97] and the diplotype G/A-T/C (P = 0.017; OR: 0.46; 95% CI: 0.24-0.88) were observed among PTB patients when compared with HCs. However, the significant differences observed for the haplotype and the diplotype were lost when corrected for multiple comparisons [Bonferroni correction: A-C-C P corrected (P(c) ) = 0.148 and G/A-T/C P(c) = 0.136]. Though the present results suggest that the CCL5 gene haplotype A-C-C and the diplotype G/A-T/C may be associated with resistance to PTB, further studies with increased sample size may be useful to confirm this present finding as well as to understand the role of CCL5 haplotype and diplotype on genetic susceptibility to TB.