IL-10-592 A/C Gene Polymorphism and Cytokine Levels are Associated with Susceptibility to Drug Resistance in Tuberculosis

Abstract

Introduction: Tuberculosis (TB) and especially resistant forms of it have a substantial economic burden on the community health system for diagnosis and treatment each year. Thus, investigation of this field is a priority for the world health organization (WHO). Cytokines play important roles in the relationship between the immune system and tuberculosis. Genetic variations especially single nucleotide polymorphisms (SNPs) impact cytokine levels and function against TB. Material and Methods: In this research SNPs in IFN-γ (+874 T/A) and IL-10 (-592 A/C) genes, and the effects of these SNPs on cytokine levels in a total of 87 tuberculosis patients and 100 healthy controls (HCs) were studied. TB patients divided into two groups: 1) 67 drug-sensitive (DS-TB) and 2) 20 drug-resistant (DR-TB) according to drug sensitivity test using polymerase chain reaction (PCR). For the genotyping of two SNPs, the PCR-based method was used and IFN-γ and IL-10 levels were measured by ELISA in pulmonary tuberculosis (PTB) and control group. Results: In -592A/C SNP, only two genotypes (AA, AC) were observed and both genotypes showed statistically significant differences between DR-TB and HCs (p=0.011). IL-10 serum levels in PTB patients were higher than HCs (p=0.02). The serum levels of IFN-γ were significantly higher in DS-TB patients than that of the other two groups (p<0.001); however, no significant differences were observed for allele and genotype frequencies in IFN-γ +874. Conclusions: Our results suggest that the SNP at -592 position of IL-10 gene may be associated with the susceptibility to DR-TB. However, further investigation is necessary. Keywords: Polymorphism, IFN-γ, IL-10, tuberculosis, drug-resistant tuberculosis