Serum MMP-3 in rheumatoid arthritis: correlation with systemic inflammation but not with erosive status.

OBJECTIVE Metalloproteinases (MMP) play an important role in the remodelling of the extracellular matrix. However, evidence that they are responsible for tissue damage in pathological situations remains circumstantial. Stromelysin (MMP-3) production is increased in rheumatoid arthritis (RA), and has been proposed as a marker of joint damage. The relevance of serum levels of MMP-3 to erosions in RA was studied. METHODS Fifty-three patients with active RA of > 5 yr duration and with available X-rays were stratified according to disease duration. Hand X-rays were scored for erosions. Patients were then classified into upper and lower quartiles. Serum MMP-3 levels were compared between these two groups. RESULTS No significant differences in serum MMP-3 were seen between high and low eroders. A statistically significant correlation was observed between sMMP-3 and erthyrocyte sedimentation rate and C-reactive protein. CONCLUSIONS Serum MMP-3 is not an independent marker of joint damage, but is correlated with systemic inflammation. Its precise role in joint damage in RA remains to be elucidated.