Serum pro-matrix metalloproteinase-3 as an indicator of disease activity and severity in rheumatoid arthritis: comparison with traditional markers

Matrix metalloproteinase-3 (MMP-3) production increases in rheumatoid arthritis (RA) and has been proposed as a marker of disease activity and joint damage. The aim of this cross-sectional study is to examine the usefulness of serum proMMP-3 as an indicator of disease activity and severity in comparison with erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Serum proMMP-3 was measured by a quantitative ELISA in 85 RA patients and 70 healthy subjects. Clinical and laboratory measures of disease activity and severity were obtained. Radiological joint damage was assessed by the method of Larsen. Serum proMMP-3 was significantly higher in RA patients than that in the healthy subjects. The active RA patients had significantly higher serum proMMP-3 than the inactive patients. Serum proMMP-3 was significantly correlated with some parameters of disease activity including swollen joints count, proximal interphalangeal joint score, morning stiffness, and Health Assessment Questionnaire; however, ESR and serum CRP were better correlated with all indicators of the disease activity than proMMP-3. The analysis of receiver operating characteristic supported that ESR and CRP had higher performance for reflection of activity compared to proMMP-3. There were no significant associations among Larsen score and proMMP-3, ESR, and CRP. Our results suggest that the cross-sectional measurement of serum proMMP-3 could not give additional information about RA disease activity compared to ESR and CRP, and could not give any information about joint damage.