Cytokine gene polymorphism as a factor of predisposition to development of chronic purulent otitis media

Abstract

In recent decades, prevalence of chronic purulent otitis media has increased markedly. A significant role in inflammation, including the pathogenesis of chronic purulent otitis media, is assigned to the cellular mediators, cytokines. The predisposing role of cytokine gene polymorphism in development of inflammatory-associated diseases has been proven. Aim. To analyze the relationship of IL1B (C3953T, C511T, T31C), IL10 (G1082A, C592A, C819T), IL6 (C174G), and TNFA (G308A) gene polymorphisms with development of chronic purulent otitis media and the age of its primary manifestation. Methods. Distribution of genotypes of allelic variants in cytokine (IL-1, IL-6, IL-10 and TNF-α) genes was analyzed in 299 patients (129 men and 170 women aged 38.0 ± 4.3) based on the age of disease onset (with chronic purulent otitis media diagnosed at age of 14, from 15 to 30, and older than 30). The control group consisted of 183 sex- and age matched healthy volunteers. Genomic DNA was isolated from whole blood leukocytes. Real-time PCR was used for determination of polymorphic variants in IL1B (-3953, -511, -31), IL10 (-1082, -592, -819), IL6 (-174), and TNFA (-308) genes. The association of genotypes with the disease was evaluated by the odds ratio (OR) and the values of Yule (Q) and contingent (Phi, Φ) coefficients. The critical significance level for the statistical hypotheses tests was taken as <0.05. Results. IL1B, IL10, and TNFA cytokine gene polymorphisms predisposed to development of chronic purulent otitis media. The genotypes C/C of C3953T and T31C polymorphisms in the IL1B gene, A/A of G1082A polymorphism, and T/T of C819T polymorphism in the IL10 gene are the most significant ones in the predisposition to disease development. Polymorphic variants of IL1B (C/C genotype of C3953T and T511C polymorphisms) and IL10 (A/A genotype of G1082A polymorphism) genes are associated with the onset of chronic purulent otitis media at age of 14. The C174G polymorphism in the IL6 gene does not predispose to the disease. Protection from the development of chronic purulent otitis media is associated with carriage of the T/T homozygous genotype of C511T and T31C polymorphisms in the IL1B gene and the G/G homozygous genotype of G1082A polymorphism in the IL10 gene. Conclusion. Polymorphisms of pro- and anti-inflammatory cytokine genes predispose to the development of chronic purulent otitis media. An imbalance of these cytokines results in a pathological course of immune response and early (children) clinical manifestation of the disease.