THE MATRIX METALLOPROTEINASE RASI-1 IS EXPRESSED IN SYNOVIAL BLOOD-VESSELS OF A RHEUMATOID-ARTHRITIS PATIENT

RASI-1 is a novel matrix metalloproteinase which we isolated from an e xpression cDNA library representing the mRNA of an inflamed synovium o btained from a patient with rheumatoid arthritis (RA). To investigate the involvement of RASI-1 in the pathology of RA, we examined synovial specimens from RA patients with antibodies directed against an unique RASI-1-derived peptide. In comparison to interstitial collagenase, ge latinase A and B, and stromelysin 1, the RASI-1 expression in the RA-s ynovium is located mainly in the tunica media of blood vessel walls an d its synovial localization is not as ubiquitous as that of other MMPs . The tissue inhibitor of metalloproteinases (TIMP-1), although also w idely expressed in the synovium, exhibits strong colocalization with R ASI-1 in blood vessel walls. While RASI-1 is expressed in blood vessel s of the inflamed synovium of an RA patient: its expression was not fo und in control synovial specimens fi om patients with luxation and art hrosis. However, RASI-1 expression can also be found in non-inflamed b lood vessels of uterine ligaments and skin. RASI-1, although its funct ion and substrates are unknown, could be involved in processes such as neovascularization and angiogenesis or lymphocyte extravasation and t hus may participate in joint tissue destruction during RA. (C) 1997 El sevier Science B.V.