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 IL1beta (interleukin-1beta), IL2, IL4, IL5, IL6, IL10, IL12p35, IL12p40, IL17, IFNgamma (interferon-gamma), TNFalpha (tumor necrosis factor-alpha), and TNFbeta mRNAs was evaluated. Using quantitative real-time RT-PCR technique, the cytokine levels, reported as Ct (cycle threshold), DeltaCt (Ct cytokine-Ct 18S rRNA) and RQ (relative quantification), in patient and control groups were compared.

RESULTS

Expression of IL1beta, IL2, IL12p35, IL12p40, IL17, TNFalpha, TNFbeta, and IFNgamma 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 IL1beta, IFNgamma, and TNFalpha 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.