Correlations Between Matrix Metalloproteinase-9 and Adenosine Deaminase Isozymes in Synovial Fluid from Patients with Rheumatoid Arthritis

Objective: To clarify the significance of increased adenosine deaminase (ADA) isozyme activities in synovial fluid (SF) from patients with rheumatoid arthritis (RA).

Methods: ADA isozyme activities were measured using colorimetric assays. Concentrations of matrix metalloproteinase-9 (MMP-9) were measured by ELISA.

Results: Levels of ADA isozyme activities in RA SF were significantly higher than those from patients with osteoarthritis and patients with traumatic injuries. Significant positive correlations between MMP-9 concentration and ADA activities were observed in RA SF (MMP-9 vs total ADA: r = 0.880; vs ADA1: r = 0.829; vs ADA2: r = 0.823; p < 0.001).

Conclusion: Elevated levels of ADA activities were found in SF from patients with RA. There were significant positive correlations between MMP-9 and ADA isozymes. These results may reflect the inflammatory condition of patients with RA.