Detection of Th17/Treg cells and related factors in gingival tissues and peripheral blood of rats with experimental periodontitis

Objective(s): This study aimed to investigate the role and the possible mechanisms involved in the immunoregulation of experimental periodontitis by Th17/Treg. Materials and Methods: Experimental periodontitis was established by silk thread ligation with Porphyromonasgingivalis daubing in the bilateral maxillary second molar of Male Sprague-Dawley (SD) rats. Alveolar bones were scanned by Micro-CT. Histological examination was stained with H&E. The proportions of Th17 and Treg cells in peripheral blood were detected by flow cytometry. RT-PCR was used to measure the expression of RORγt, Foxp3 mRNA in the gingival tissues. The concentrations of IL-17, IL-10, and TGF-β in peripheral blood and gingival crevicular fluid were measured by ELISA. Results: Experimental rats showed profound bone resorption and inflammatory cell infiltration. The percentages of Th17 significantly increased in the peripheral blood, which was consistent with gingival tissues study that Th17 cells related transcription factor RORγt mRNA and IL-17 increased in the course of periodontitis. The percentages of CD25+Foxp3+ Treg significantly increased in the peripheral blood, which was consistent with gingival tissues study that Treg cells related transcription factor Foxp3 mRNA and cytokines IL-10 and TGF-β increased in the course of periodontitis. The ratio of Th17/Treg cells was significantly increased in the peripheral circulation, however, the Th17/Treg balance is in wave motion in inflamed gingival tissues in the different stages of periodontitis. Conclusion: Th17/Treg balance may be associated with the progression of periodontitis and pathological tissue destruction. Moreover, local inflammation would result in the up-regulation ratio of Th17/Treg in peripheral blood, which may influence some periodontally involved systemic diseases.