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.
SF was obtained from 25 TMJs in 22 patients with internal derangement (ID) or osteoarthritis (TMJ-OA), 15 asymptomatic TMJs in 11 normal volunteers, and 10 osteoarthritic knee joints (KNEE-OA). Cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA), and the proteinase activities were detected by enzymography.
SF from TMJs with ID and OA showed higher (P < .05) levels (330.1 +/- 347.7 pg/100 microg SF protein) of IL-1beta than the asymptomatic control TMJs (76.7 +/- 95.3 pg/100 microg of SF protein). SF from TMJs with OA contained significantly (P < .05) higher levels of IL-1beta (531.8 +/- 379.6 pg/100 microg of SF protein) and IL-6 (979 +/- 552 pg/100 microg SF protein) than those with ID (IL-1beta: 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-OA. Also detected were weak bands with molecular weight of 83 and 66 kDa. These bands were clearly shown, particularly in knee joints with advanced stages of OA. 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-1beta and IL-6.
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.