Anti-Inflammatory Treatments Reduce Proinflammatory Cytokine Levels in the TMJ

Objectives: Previous results from this group demonstrated that adjuvant-induced inflammation of the TMJ produced a significant increase in inflammatory mediators within the tissues of the TMJ. The goal of this study was to examine the effects of three different anti-inflammatory drugs on the expression of proinflammatory cytokines during inflammation of the TMJ. Methods: Adult (200-225 g) male Sprague Dawley rats were assigned to one of four groups (n=12/group): group 1 no treatment (CON), group 2 injected with complete Freund's adjuvant (CFA, 50 mg in 50 ml of paraffin oil) into the TMJ and no therapeutic treatment (CFA-DRUG), group three CFA and treated daily with either ibuprofen, a COX-2 inhibitor, or dexamethasone (CFA+DRUG), or group 4 no CFA and one of the three therapeutics (CON+DRUG). The rats were sacrificed 48 hours after CFA treatment and TMJ tissues were removed and homogenized. Protein was extracted and ELISAs were run to examine changes in the expression of IL-1b, IL-6, and TNF-a. Results: Analysis of the ELISA results indicate that IL-1b, IL-6, and TNF-a levels were significantly increased in the inflamed CFA treated TMJ tissues (p£0.01). No significant differences were observed in either the CON or CON+DRUG groups. However, both dexamethasone (p£0.01) and the COX-II-I (p£0.05) produced a significant decrease in levels of all three proinflammatory cytokines, while significant reductions were observed only for IL-1b after ibuprofen (p£0.05). Conclusions: This study demonstrates that treatment of adjuvant-induced inflammation of the TMJ with various anti-inflammatory therapeutics resulted in a change in the expression of the proinflammatory mediators IL-1b, IL-6, and TNF-a during the acute stage of inflammation of the TMJ. Dexamethasone appeared to have the greatest effect on levels of all of the inflammatory mediators. This study was supported in part by NIH/NIDCR Traineeship T35 DE07188 and the Baylor Oral Health Foundation.