Polymorphism at position-174 of IL-6 gene is associated with susceptibility to chronic periodontitis in a Caucasian Brazilian population

Background: Interleukin-6 (IL-6) is a multifunctional cytokine that mediates inflammatory tissue destruction. A G to C substitution at position -174 in the promoter of IL-6 gene reduces in vitro transcription of IL-6. This polymorphism has been associated with inflammatory diseases like chronic arthritis. Objective: The aim of this study was to investigate the association between the IL-6(-174) polymorphism and susceptibility to chronic periodontitis in Brazilians. Material and Methods: Eighty-four nonsmoking subjects over 25 years (mean age 42.4) were divided according to the severity level of periodontal disease: 36 healthy individuals (control group), 24 subjects with moderate and 24 with severe periodontitis. Genomic DNA was obtained from epithelial cells through a mouthwash with 3% glucose and scraping of oral mucosa. The samples were analyzed for IL-6(-174) polymorphism using PCR-RFLP. The significance of the differences in the frequencies of the polymorphism in the control and groups with periodontitis was assessed by chi(2) test (p <0.05). Results: Differences were found between control and groups with periodontitis in the genotype (p =0.0036, OR=3.0) and in the allele (p =0.0838, OR=1.9) frequencies. Conclusion: We concluded that the IL-6(-174) polymorphism is associated with susceptibility to chronic periodontitis in the population studied.