CHARACTERIZATION OF EQUINE MATRIX METALLOPROTEINASE-2 AND METALLOPROTEINASE-9 - AND IDENTIFICATION OF THE CELLULAR SOURCES OF THESE ENZYMESIN JOINTS

The cellular production by resident articular cells and infiltrating i nflammatory cells of the gelatinase matrix metalloproteinases (MMP) wa s investigated by tissue culture methods and analysis of cell supernat ants by gelatin zymography. Peripheral blood neutrophils in short term culture produced MMP-9, as did peripheral blood monocytes in culture. Isolated articular chondrocytes in monolayer culture produced both MM P-2 and MMP-9, although articular cartilage maintained as explant cult ure produced MMP-2 alone. Synovial fibroblasts grown in monolayer cult ure produced MMP-2 alone, although synovial membrane in explant cultur e produced both MMP-2 and the active form of MMP-2, Lysis of blood pol ymorph neutrophils produced large quantities of MMP-9, but lysis of bl ood monocytes, synovial fibroblasts and articular chondrocytes produce d little enzyme indicating that, unlike the other cell types, polymorp h neutrophils store MMPs intracellularly, Equine MMP-2 was purified fr om synovial fibroblast cell culture supernatant, and equine MMP-9 from polymorph neutrophil cell culture supernatant, by gelatin-sepharose a ffinity chromatography, The 2 enzymes were identified from their molec ular weights and by their respective N-terminal amino acid sequences w hich showed homology with the enzymes from other species. The demonstr ation that invasive cells and resident articular cells can produce enz ymes which are capable of digestion of certain component molecules of the articular cartilage matrix, shows that therapeutic targeting of th ese enzymes could be a valid proposition in the prevention of cartilag e destruction in osteoarthritis.