Genetic polymorphisms of interleukin-16 in Egyptian patients with primary knee osteoarthritis

BackgroundThe pro-inflammatory cytokine, interleukin 16 (IL-16), has been shown to be secreted in low levels in knee osteoarthritis (KOA). The aim of the study was to examine the relationship between IL-16 polymorphisms and the risk of KOA in the Egyptian population, as well as the clinical and radiographic severity of KOA.ResultsIL16 rs11556218 thymidine triphosphate (T) T G (guanosine triphosphate), GG, TG + GG genotypes, and G allele (odd ratio (OR) = 0.315; 95% confidence interval (CI) = 0.191-0.518; P < 0.001; OR = 0.363; 95% CI = 0.162-0.815, P = 0.014; OR = 0.323; 95% CI = 0.202-0.519, P < 0.001; OR = 0.480; 95% CI = 0.338-0.683, P < 0.001 respectively); rs4778889 cytidine triphosphate (C) T,CC, TC + CC genotypes, and C allele (OR = 0.519, 95% CI = 0.319-0.844, P = 0.008; OR = 0.309, 95% CI = 0.105-0.916, P = 0.034; OR = 0.485, 95% CI = 0.304-0.775, P = 0.002; OR = 0.537, 95% CI = 0.365-0.791, P = 0.001 respectively); and rs4072111 CT, TT, CT + TT genotypes, and T allele (OR = 0.537, 95% CI = 0.323-0.893, P = 0.017, OR = 0.316, 95% CI = 0.096-0.843, P = 0.049, OR = 0.502, 95% CI = 0.309-0.816, P = 0.005; OR = 0.534, 95% CI = 0.353-0.809, P = 0.004 respectively) were associated with a decreased KOA risk, and they were significantly associated with decreased the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and the Kellgren-Lawrence (K/L) scores.Neither IL-16 serum levels nor IL-16 polymorphisms were associated with the susceptibility to KOA. Low KOA risk was associated with the haplotypes GTC and TCT.ConclusionThere was no correlation between serum IL-16 levels and KOA susceptibility or IL-16 polymorphisms. GTC and TCT haplotypes were associated with low KOA risk. The variant alleles rs11556218GG, TG + GG; rs4778889 CC, TC + CC; and rs4072111 TT, CT + TT were associated with a reduced risk of KOA.