Single nucleotide polymorphisms in IFN-gamma, TNF-alpha, IL-6, IL-10, and TGF-beta in pulmonary and extrapulmonary tuberculosis in the state of Ceará, northeastern Brazil

Abstract

Background: Single nucleotide polymorphisms (SNP) in genes encoding cytokines influence tuberculosis (TB) outcomes. Objectives: To characterize genotypes of the SNPs IFN-gamma +874 T>A, TNF-alpha-308 G>A, IL-6-174 G>C, IL-10-1082A>G, TGF-beta codon 10 T>C, and TGF-beta codon 25 G>C in patients with pulmonary (PTB) and extrapulmonary TB (EPTB). Methods: 82 PTB and 45 EPTB cases were compared, concerning genotype distribution of the mentioned SNPs, characterized via sequence-specific primer PCR. Findings: Regarding IFN-gamma +874 T>A, AA genotype was the most frequent in both groups, TA was more frequent in PTB and TT in EPTB, with no statistical significance. For SNP TNF-alpha-308 G>A, GG was more frequent in both groups of patients. Regarding the IL-6-174 G>C polymorphism, GG predominated in both groups, while CG and GG were significantly more frequent in patients with PTB and EPTB, respectively. Concerning IL-10-1082 A>G, AA predominated in both PTB and EPTB. Concerning TGF-beta codon 10 T>C, CC predominated in PTB while TC predominated in EPTB, but the differences were not statistically significant. Genotype GG of TGF-beta codon 25 G>C predominated among PTB and EPTB patients. Main conclusions: Except for IL-6, the genotype profile could not differentiate PTB and EPTB. Hence, the studied SNPs are not significantly associated with the extrapulmonary involvement of TB.