Interleukin-2 −330 and 166 gene polymorphisms in relation to aggressive or chronic periodontitis and the presence of periodontopathic bacteria

Background and Objective: As a pro‐inflammatory cytokine, interleukin‐2 mediates the activation, growth and differentiation of T and B lymphocytes and natural killer cells. Promoter polymorphisms of the interleukin‐2 gene have been associated with altered interleukin‐2 production or identified as prognostic markers for various infectious diseases. Therefore, the aim of this study was to evaluate two polymorphisms at positions −330 T/G and 166 G/T in patients with generalized chronic periodontitis (n = 58) or generalized aggressive periodontitis (n = 73) in comparison with periodontitis‐free controls (n = 69). Material and Methods: Both interleukin‐2 polymorphisms were analyzed using the polymerase chain reaction with sequence‐specific primers. Distributions of single alleles, genotypes and haplotypes were calculated using the chi‐square test. Risk factor analyses were carried out by logistic regression with respect to established cofactors for periodontitis. The presence of subgingival bacteria in an individual were analyzed using a molecular biological method (the micro‐Ident® test). Results: The interleukin‐2 genotype −330 TG occurred less frequently in patients with chronic periodontitis (25.9% vs. 49.3%). Moreover, this genotype decreased the adjusted odds ratio for chronic periodontitis (odds ratio = 0.394), whereas the interleukin‐2 genotype 166 TT and the haplotype combination interleukin‐2 −330,166 TT : TT were associated with an increased adjusted odds ratio (odds ratio = 2.82 or 2.97). For the latter interleukin‐2 combination, a positive association for the subgingival presence of Porphyromonas gingivalis (81.3% vs. 59.5%) and bacteria of the ‘red complex’ (78.1% vs. 56.0%) was shown. Conclusion: The interleukin‐2 genotypes −330 TG and 166 TT, as well as the combination genotype interleukin‐2 TT : TT, could be putative prognostic factors for chronic periodontitis.