Interleukin-17AGene Variability in Patients with Type 1 Diabetes Mellitus and Chronic Periodontitis: Its Correlation with IL-17 Levels and the Occurrence of Periodontopathic Bacteria

Abstract

Interleukin-17 contributes to the pathogenesis of type 1 diabetes mellitus (T1DM) and chronic periodontitis (CP). We analyzedIL-17A−197A/G andIL-17F+7488C/T polymorphisms in T1DM and CP and determined their associations with IL-17 production and occurrence of periopathogens. Totally 154 controls, 125 T1DM, and 244 CP patients were genotyped using 5′ nucleaseTaqMan®assays. Bacterial colonization was investigated by a DNA-microarray kit. Production of IL-17 afterin vitrostimulation of mononuclear cells by mitogens and bacteria was examined by the Luminex system. Although no differences in the allele/genotype frequencies between patients with CP and T1DM + CP were found, theIL-17A−197 A allele increased the risk of T1DM (P<0.05). Levels of HbA1c were significantly elevated in carriers of the A allele in T1DM patients (P<0.05). Production of IL-17 by mononuclear cells of CP patients (unstimulated/stimulated byPorphyromonas gingivalis) was associated withIL-17AA allele (P<0.05).IL-17Apolymorphism increased the number ofTannerella forsythiaandTreponema denticolain patients with CP and T1DM + CP, respectively (P<0.05).IL-17Agene variability may influence control of T1DM and the “red complex” bacteria occurrence in patients with CP and T1DM + CP. Our findings demonstrated the functional relevance of theIL-17Apolymorphism with higher IL-17 secretion in individuals with A allele.