In vivo effects of antirheumatic drugs on neutral collagenolytic proteases in human rheumatoid arthritis cartilage and synovium.

The destruction of joints in rheumatoid arthritis (RA) is thought to be related in part to an increased synthesis of proteolytic enzymes. We have determined neutral collagenolytic protease activity levels in human RA synovia and articular cartilage and examined the in vivo effects of various therapeutic regimens on enzyme levels. Neutral metallocollagenolytic enzyme (NMCE) was measured in 29 RA cartilages and synovial membranes. In addition, synovial serine protease levels were determined. Specimens were divided into 4 groups according to prescribed medications: (1) nonsteroidal antiinflammatory drugs alone; (2) steroids alone; (3) steroids and gold; and (4) steroids and methotrexate (MTX). Ten normal specimens were used as controls. Total and active NMCE measured in both RA cartilage and synovial membrane specimens showed a significantly higher level of activity than in controls (p less than 0.0001, p less than 0.005; p less than 0.004, p less than 0.02). MTX was found to markedly decrease NMCE activity; cartilage NMCE level in patients with RA receiving MTX was reduced, compared to the other subgroups. This was particularly noted for the active form. Synovial NMCE levels from the MTX subgroup for both enzyme forms were much lower than in any other RA subgroup, significantly lower than in the RA group as a whole (p less than 0.05), and similar to controls. RA synovial membrane serine protease activity showed an increase compared to controls. Again, MTX markedly decreased the activity of this class of enzyme. Our data strongly support the role of neutral proteases in the destruction of RA joints. MTX was the only drug to consistently decrease these enzyme levels in joint tissues.