Green Tea Modulates Cytokines Expression in Periodontium of Diabetic Rats

Diabetes mellitus comprise a heterogeneous group of disorders, in which hyperglycemia is a main feature. Chronic hyperglycemic increases the severity of periodontal diseases due to an exacerbated inflammatory response triggered by the AGE/RAGE system. Therefore, anti-inflammatory agents are potential targets to interfere in this pathological interaction. The green tea is described to present anti-inflammatory properties mediated by its polyphenol content. Objectives: To investigate the mechanisms by which green tea attenuates the spontaneous onset of diabetes-triggered periodontitis. Methods: Diabetes was induced in rats by single intraperitoneal injection of streptozotocin. Diabetic and control animals were subdivided in water or green tea treated  and analyzed at 15, 30, 60 and 90 days after diabetes induction.  Immunohistochemistry was performed to quantitative evaluation of TNF-α, RANKL, OPG, IL-10 and RUNX-2 in serial sections of the each hemimaxillae. Morphometrical measurements were performed beginning from the cementum enamel junction (CEJ) of superior first molar distal root to the alveolar (ABC) bone crest and bone loss measurements were obtained. Results: Diabetes resulted in significant bone loss and alterations in number of immunostaining cells to inflammatory mediators. In diabetic rats treated with green tea, we observed a decreased number of immuno-staining cells to RANKL and TNF-α in relation to diabetic rats treated with water. On the other hand, the green tea increased immunostaining cells to OPG, RUNX-2 and IL-10 in diabetic rats. Conclusions: The results demonstrate that green tea intake act in favor of a normalization of mediators’ expression, in order to reduce the expression of pro-inflammatory cytokine TNF-a and the osteoclastogenic mediator RANKL; while increasing the expression of anti-inflammatory cytokine IL-10, the  osteogenesis related factor RUNX2 and the anti-osteoclastogenic factor OPG.  Thus, green tea seems to be a possible therapeutic agent to periodontal disease treatment associated with diabetes.