IL-1 alpha (-889) promoter polymorphism is a risk factor for osteomyelitis

Abstract

As osteomyelitis (OM) induces the synthesis of inflammatory cytokines and IL-1 mediates bone resorption by osteoclasts we determined if there is an association between certain common polymorphisms of the genes encoding proinflammatory cytokines (IL-1 alpha and beta, IL-6, TNF-alpha) and OM in adults. The IL-1 alpha (-889) TT genotype was significantly more frequent among 52 OM patients than in 109 healthy controls (13/52, [25.0%] vs. 9/109, [8.3%], P = 0.0081, chi(2) = 7.01, OR = 3.7, 95% CI, 1.35-10.34). Patients who were homozygous for the T allele were younger than the rest of the OM patients (mean age 35.7 +/- 11.5 vs. 58.1 +/- 18.6 years, P = 0.001). IL-1 beta TT (+3953) polymorphism was also more frequent in OM patients (P = 0.014, chi(2) = 5.12, OR = 5.1, 95% CI, 1.21-52.14), but IL-1 beta is in linkage disequilibrium with the IL-1 alpha *T (P < 0.001). Route of infection, chronicity of the infection, type of microorganism isolated, and frequency of relapses were similar in patients with and without the IL-1 alpha TT genotype. There were no associations between OM and polymorphisms of other cytokines genes. IL-1 alpha serum levels were significantly increased in all the OM patients independently of their IL-1 genotype compared to the controls (P = 0.021). Although IL-1 alpha serum levels were not significantly higher in patients with the IL-1 alpha (-889) polymorphism, this does not exclude a difference in production of IL-1 alpha by osteoclasts or other inflammatory cells at the site of infection.