Expression of proinflammatory cytokines in osteoarthritis of the temporomandibular joint

Objective: This study reports the expression of proinflammatory cytokines in temporomandibular joint (TMJ) of patients affected with temporomandibular osteoarthritis (OA). Design: In twelve OA of the TMJ (OA-TMJ) affected patients and in six healthy volunteer subjects studied as control, the expression of IL1 beta (interleukin-1 beta), IL2, IL4, IL5, IL6, IL10, IL12p35, IL12p40, IL17, IFN gamma (interferon-gamma), TNF alpha (tumor necrosis factor-alpha), and TNF beta mRNAs was evaluated. Using quantitative real-time RT-PCR technique, the cytokine levels, reported as Ct (cycle threshold), Delta Ct (Ct cytokine-Ct 18S rRNA) and RQ (relative quantification), in patient and control groups were compared. Results: Expression of IL1 beta, IL2, IL12p35, IL12p40, IL17, TNF alpha, TNF beta, and IFN-gamma mRNAs was significantly higher in patients as compared with controls. In particular, IL12 was the predominant cytokine expressed in patients (IL12p35 RQ = 30.2 and IL12p40 RQ = 29.0). Conversely, IL10 mRNA levels were higher in controls (RQ = 1.8). Conclusions: These data suggest that not only IL1 beta, IFN-gamma, and TNF alpha but also IL10, IL12, and IL17 are involved in the OA-TMJ pathogenesis. Furthermore, an inflammatory response characterised by the predominant expression of IL12 mRNA and down-regulated expression of IL10 mRNA is associated with the degenerative changes observed in OA-TMJ. (c) 2008 Elsevier Ltd. All rights reserved.