Lack of association of a functional polymorphism in the interleukin 8 gene with susceptibility to periodontitis.

The important inflammatory mediator interleukin-8 (IL-8) is responsible for the migration and activation of neutrophils. The IL8 gene contains a functional single-nucleotide polymorphism (SNP) (rs4073) in its promoter region that may influence the expression of IL-8, and which has been associated with inflammatory diseases. The purpose of this study was to investigate the association of the SNP (rs4073) in the IL8 gene with susceptibility to periodontitis. DNA was extracted from the buccal epithelial cells of 500 individuals (control n = 224 and periodontitis n = 276). Individuals were genotyped for the SNP (rs4073) using sequence-specific primer polymerase chain reaction. Associations between the SNP (rs4073) and subject phenotypes were analyzed using the chi-squared test, followed by univariate and multivariate logistic regression modeling. The genotype distributions in both groups were consistent with Hardy-Weinberg equilibrium. Univariate and multivariate analysis showed that age, skin color, and smoking status were associated with periodontitis. No significant differences were found for sex and frequencies of alleles and genotypes between the control and periodontitis groups in the univariate analysis. These findings were replicated in the multivariate analysis. The SNP (rs4073) in the IL8 gene is not associated with susceptibility to periodontitis in Brazilian individuals, even after controlling for covariates.