We evaluated the role of interleukin-17 in the progression of periodontitis focusing on 1) the presence of mRNA expression of IL-17 and T cell cytokines in periodontal tissues, evaluated using RT-PCR and direct sequencing, IL-17 production in gingival crevicular fluid (GCF) by ELISA and cultured periodontitis tissues by Western blot analysis ; and 2) whether recombinant human IL-17 (rhIL-17) and culture supernatants of periodontitis tissues induced IL-6 production from cultured human gingival

more »

... broblasts (HGF) . We detected IL-17 mRNA expression in periodontitis tissues, detected by Western blotting, IL-17 in GCF samples was not detectable. T cells in periodontitis tissues simultaneously expressed mRNA encoding IL-17 and mRNAs of IFN-y, IL-2, osteoclast differentiation factor (ODF) and osteoclastgenesis inhibitory factor (OCIF) , which belong to Th 1 cytokines or bone metabolic molecules (Fisher's exact test) , whereas the mRNA of IL-4, which is a Th 2 cytokine, was not expressed rhIL-17 induced IL-6 production by HGF in time-and dose-dependently. These findings indicate that activated T cells in periodontitis lesions produced IL-17, a Th 1 cytokine and bone metabolic molecule that may be responsible for enhancing inflammatory reactions and bone resorption via gingival fibroblast-derived mediators in periodontal disease.