Toll-like receptor 2 polymorphisms and their effect on the immune response to ESAT-6, Pam3CSK4 TLR2 agonist in pulmonary tuberculosis patients and household contacts

Abstract

Toll-like receptors (TLRs) play a pivotal role in organizing the effective immune response through inducing the pro-inflammatory cytokines for control of tuberculosis infection and TLR polymorphisms are associated with altered cytokine levels have been described. Therefore, the main aim of the present study was to confirm whether TLR2 (C2029T, G2258A) polymorphisms effects the cytokine production in PTB patients and Household contacts (HHC), healthy controls (HC). The polymorphisms were performed by amplification refractory mutation system-polymerase chain reaction (ARMS) & Restriction Fragment Length Polymorphism (RFLP) in 336 subjects. Cytokine levels were estimated in Pam3CSK4, antigen ESAT-6 stimulated culture supernatants by Enzyme-Linked Immunosorbent Assay. Under the over-dominant model GA genotype of G2258A SNP and CT genotype of the co-dominant model in C2029T SNP showed a susceptible effect in patients, whereas in HHC, CT genotype showed a protective effect. A significant decreased TNF-α, IL-12 and increased IL-1β levels were observed after Pam3CSK4, antigen ESAT-6stimulation; our results showed the following associations: TLR2 G2258A SNP of GA with decreased TNF-α; TLR2 C2029T SNP of CT, TT with decreased IL-12 and increased IL-1β levels. Regression analysis demonstrated that age, BCG, gender and T allele were significantly associated with TB. Pre-mRNA secondary structure of the A, T alleles are more stable than G, C alleles. Altogether, we suggest that cytokine levels, 2029T allele, TLR2 polymorphisms were considered as predictive markers for identification of high-risk individuals in TB.