IMMUNOLOCALIZATION STUDIES ON 6 MATRIX METALLOPROTEINASES AND THEIR INHIBITORS, TIMP-1 AND TIMP-2, IN SYNOVIA FROM PATIENTS WITH OSTEOARTHRITIS AND RHEUMATOID-ARTHRITIS

Objective-To assess the likely importance of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) in the arthritic process. Methods-Synovial samples from seven joints with rheumatoid arthritis and three osteoarthritic joints were analysed by indirect immunofluorescence microscopy. Using specific human antisera, we documented the frequencies and distributions of collagenase, stromelysins 1 and 2, matrilysin, gelatinases A and B, TIMP-1, and TIMP-2. Results-Stromelysin 1 was found in all synovia, bound to extracellular matrix, within cells, or both, indicating stromelysin synthesis. Matrilysin was present in only one active inflammatory synovium, and focal synthesis of collagenase and gelatinase A was seen in four synovia. Stromelysin and TIMP-2 were not observed, but TIMP-1 synthesis was seen in five synovia, and in two active synovia the distribution of TIMP-1 positive cells was more widespread than that of MMPs. Conclusions-The presence of stromelysin 1 all synovia clearly implicates enzyme Collagenase, gelatinase A and matrilysin may also have a role in rheumatoid arthritis, but are not significant in osteoarthritis. However, marked regional variations were found in the synthesis of these MMPs, indicating not only that these diseases are episodic but that control of enzyme synthesis is focal. Only TIMP-1 may be considered an inhibitory factor.