Importance of proinflammatory cytokines in synovial fluid from 121 joints with temporomandibular disorders

The concentrations of cytokines were measured by an ELISA in the synovial fluid from 117 patients with temporomandibular disorders (TMD) and correlated with degenerative changes of the condyle and clinical symptoms. Fifty-seven patients had degenerative changes of the condyle. The fluid from seven healthy volunteers was used as controls. The concentrations of interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-8 (IL-8) were significantly higher in the synovial fluid of patients than controls (P<0.05). The concentration of IL-6 was significantly higher in the patients with degenerative changes than in other patients (P<0.05). The detection of IL-8 correlated with the concentrations of IL-6 and TNF-α. However, there was no correlation between the concentrations of any cytokines and symptoms. In conclusion, the cytokines in the synovial fluid may participate in the pathogenesis of TMD. In particular, IL-6 is important and may be associated with the development of osteoarthritis.