Matrix metalloproteinase-3 serum levels are correlated with disease activity and predict clinical response in rheumatoid arthritis

OBJECTIVE: To demonstrate that serum matrix metalloproteinase-3 (MMP-3) is a variable associated with disease activity and with the response to treatment in rheumatoid arthritis (RA). METHODS: Serum MMP-3 levels were measured and compared to biological and clinical disease activity variables in 20 patients with active RA assessed serially during a one year prospective open label trial with methotrexate or tenidap. RESULTS: MMP-3 levels were significantly correlated with C-reactive protein (CRP) and interleukin 6 serum levels as well as with the disease activity score (DAS), not only at start in untreated patients but also during the 12 month followup period in both treated groups. Early changes (after 0.5, 1, 2, or 3 months) in MMP-3 levels were significantly associated with change in DAS observed 4 to 6 months later. CONCLUSION: In addition to CRP, a systemic marker of inflammation, serum MMP-3 may serve as a consistent synovial derived marker of RA disease activity, early changes of which predict disease outcome.