MMP-3 as a Biomarker of Disease Activity of Rheumatoid Arthritis

The aim of this study was to confirm the clinical significance of serum MMP-3 measurement in the evalua- tion of disease activity and effectiveness of treatment in patients with rheumatoid arthritis (RA). MMP-3 was measured for 206 outpatients with RA during a period of 4 months, and also serially measured for RA patients treated with methotrexate(MTX) alone or together with infliximab (IFX). Serum MMP-3 was significantly correlated with CRP, SAA, and ESR. Significant correlation of serum MMP-3 was found not only with DAS28 (CRP) in female and male patients (p <0.0001 and p < 0.0051, respectively) but also with the EULAR classification criteria for the disease activity of RA. Among the items of DAS28(CRP), the strongest association of MMP-3 was found with swollen joint counts. Furthermore, MMP-3 levels increased with advances in Stage and Class of RA. MMP-3 levels gradually decreased 12 and 24 weeks after successful treatment with MTX (p=0.0188 and p=0.0179, respectively). Extent of the decrease was more prominent in patients with better response to MTX than in those with poor response. MMP-3 levels significantly decreased 6 weeks after IFX treatment and continued to decrease until 48 weeks. Significant decrease of MMP-3 level from before treatment was shown only in the good response group to IFX after 48 weeks of treatment. MMP-3 level was shown to be useful as a disease activity marker in RA patients. In addition, serial measurement of MMP-3 maybe helpful to evaluate the effect of treatments with MTX and IFX.