Analyzing IL6 gene polymorphism in patients with various clinical forms of pulmonary tuberculosis

Abstract

Throughout the world, tuberculosis still remains one of the most important public health problems. According to numerous publications, TB infectrion is considered as a genetically determined disease, and host genetical polymorphism underlies a mechanism resulting in disease progression from primary infection to clinical manifestations. Currently, an association between TB infection and IL6 gene polymorphism at position -174 responsible for low cytokine production has been extensively investigated. Previously, we evaluated the association between IL6 gene alleles and genotypes and predisposition/resistance to tuberculosis in Russian descendants residing in the Chelyabinsk Region. Here, we conducted a comparative analysis for prevalence of IL6 gene alleles and genotypes in patients differed in lung damage degree such as infiltrative, focal, and fibrous-cavernous forms of pulmonary tuberculosis by isolating whole blood DNA samples and subsequent genotyping of IL6 gene polymorphisms with polymerase chain reaction and agarose gel electrophoresis. We found that patients with a focal TB form were characterized by prevalence of IL6(-174)*C/C genotype associated with low cytokine production, whereas patients with severe fibrous-cavernous carried IL6(-174)*G/C genotype accounting for modedrated IL-6 production.