Analysis of IL-6 and IL-8 gene polymorphisms and their association with cytokine levels in sinus infections

Abstract

Objective: Sinusitis is a common inflammatory condition influenced by both genetic predisposition and variations in immune responses. Among the key regulators of inflammation, interleukin-6 (IL-6) and interleukin-8 (IL-8) play pivotal roles in coordinating immune signalling and leukocyte recruitment. This study investigated whether polymorphisms in the IL-6 and IL-8 genes are associated with susceptibility to sinus infections and whether these genetic variants influence circulating cytokine levels.

Methods: A total of 48 patients with sinus infections and 48 matched healthy controls were genotyped for IL-6 (-174 G/C) and IL-8 (-251 A/T) polymorphisms using Amplification Refractory Mutation System-Polymerase Chain Reaction (ARMS-PCR). Serum cytokine levels (IL-10, IL-1α, and IFN-γ) were measured by enzyme-linked immunosorbent assay (ELISA). Statistical comparisons were performed using Chi-square tests, t-tests, and odds ratio analyses.

Results: Significantly elevated levels of IL-10 (2.88 ± 0.69 pg/ml) and IL-1α (12.99 ± 1.03 pg/ml) were observed in patients compared to controls (0.436 ± 0.09 pg/ml and 5.54 ± 2.05 pg/ml, respectively; P = 0.002). The IL-6 GG genotype was present in 75% of patients but only 4.16% of controls, while the IL-8 TT genotype was found exclusively in patients. Protective genotypes (IL-6 GC and IL-8 AT) were more frequent in controls. Although cytokine levels did not differ significantly by genotype, trends suggested a more pro-inflammatory profile among high-risk genotypes.

Conclusion: IL-6 and IL-8 gene polymorphisms may influence susceptibility to sinus infections by modulating host immune responses. These variants may serve as potential biomarkers for identifying individuals at elevated risk for chronic or recurrent sinusitis.