Genetic polymorphisms of interleukin-16 are associated with susceptibility to primary knee osteoarthritis.

Interleukin-16 (IL-16) polymorphisms have been associated with various disease states, and its activity is dysregulated in synovial fibroblasts of individuals with rheumatoid arthritis. Here, the association between genetic polymorphisms in the gene encoding IL-16 and susceptibility to primary knee osteoarthritis was investigated in the Chinese Han population. The study included 228 unrelated patients, half of whom presented with primary knee osteoarthritis (OA); the remainder was healthy individuals. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to examine single nucleotide polymorphisms (SNPs) in IL16 in these patients. Statistical analysis was performed using the chi-square goodness-of-fit test, Hardy-Weinberg (H-W) equilibrium, linkage disequilibrium analysis, and logistic regression analysis. The genotype distributions of three IL16 SNPs, rs11556218, rs4778889, and rs4072111, were found to be in line with Hardy-Weinberg equilibrium criteria (P > 0.05). The single-factor logistic regression analysis showed that, compared with the T/T genotype, the T/G genotype decreased the risk of primary knee OA in rs11556218 (OR = 0.37, 95% CI = 0.18~0.82) and, compared with the C/C genotype, the C/T genotype increased the risk of primary knee OA in rs4072111 (OR = 1.83, 95% CI = 1.07~3.59). There was linkage disequilibrium between rs4778889 and rs11556218 (D= 0.592, r(2) = 0.213). Finally, logistic regression analysis showed that compared to haplotype TTC, the TTT haplotype was associated with an increased risk of primary knee OA (OR = 2.10, 95% CI = 1.09-4.98); however, the GCC haplotype was associated with a reduced risk of primary knee OA (OR = 0.36, 95% CI = 0.12-0.93). Thus, the genetic polymorphisms rs11556218, rs4778889, and rs4072111 in the gene encoding IL-16 are associated with primary knee OA in Chinese Han population.