Synovial fluid cytokines and proteinases as markers of temporomandibular joint disease

Purpose: In this article, biochemical markers in the synovial fluid (SF) for detecting intraarticular inflammation and early cartilage degradation of the temporomandibular joint (TMJ) disease were examined. Patients and Methods: SF was obtained from 25 TMJs in 22 patients with internal derangement (ID) or osteoarthritis (TMJ-GA), 15 asymptomatic TMJs in 11 normal volunteers, and 10 osteoarthritic knee joints (KNEE-GA). Cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA), and the proteinase activities were detected by enzymography. Results: SF from TMJs with ID and OA showed higher (P<.05) levels (330.1 +/- 347.7 pg/100 mu g SF protein) of IL-1 beta than the asymptomatic control TMJs (76.7 +/- 95.3 pg/100 mu g of SF protein). SF from TMJs with GA contained significantly (P<.05) higher levels of IL-1 beta (531.8 +/- 379.6 pg/100 mu g of SF protein) and IL-6 (979 +/- 552 pg/100 mu g SF protein) than those with ID (IL-1 beta: 216.7 +/- 280.1 pg, IL-6: 293 +/- 434 pg). Two matrix metalloproteinases (MMPs) with gelatinolytic activities at 92 kDa and 72 kDa were consistently detected in both the TMJ-SF (either normal or disease) and SF from KNEE-GA, Also detected were weak bands with molecular weight of 83 and 66 k;Da. These bands were clearly shown, particularly in knee joints with advanced stages of GA. Western blot analysis delineated that these were active forms of MMP-9 (83 kDa) and MMP-2 (66 kDa). The same bands were also detected in TMJs with OA that showed high levels of IL-1 beta and IL-6. Conclusion: These findings suggest that concomitant increases in the levels of cytokines (IL-1 and IL-6) and active forms of MMPs could be potential catabolic markers for cartilage degradation in the TMJ.