Effects of etanercept, a tumour necrosis factor-α antagonist, in an experimental model of periodontitis in rats

Background and purpose: Etanercept is a tumour necrosis factor antagonist with anti-inflammatory effects. The aim of our study was to evaluate, for the first time, the therapeutic efficacy of in vivo inhibition of TNF-α in an experimental model of periodontitis. Experimental approach: Periodontitis was induced in adult male Sprague-Dawley rats by placing a nylon thread ligature around the lower 1st molars. Etanercept was administered at a dose of 5 mg kg ^-1, s.c., after placement of the ligature. Key results: Periodontitis in rats resulted in an inflammatory process characterized by oedema, neutrophil infiltration and cytokine production that was followed by the recruitment of other inflammatory cells, production of a range of inflammatory mediators, tissue damage, apoptosis and disease. Treatment of the rats with etanercept (5 mg kg ^-1, s.c., after placement of the ligature) significantly reduced the degree of (1) periodontitis inflammation and tissue injury (histological score), (2) infiltration of neutrophils (MPO evaluation), (3) iNOS (the expression of nitrotyrosine and cytokines (eg TNF-α)) and (4) apoptosis (Bax and Bcl-2 expression). Conclusions and Implications: Taken together, our results clearly demonstrate that treatment with etanercept reduces the development of inflammation and tissue injury, events associated with periodontitis.