Synovial extracellular matrix: partial characterization of matrix components and identification of type VI collagen molecular forms.

Alterations in the synovial extracellular matrix (ECM) in chronic inflammatory arthritis may affect synoviocyte adhesion and may be important in the regulation of pannus growth and invasion. Immunohistochemical examination of synovium has revealed enhanced deposition of fibronectin and collagen in interstitial areas consistent with expansion of the ECM in inflammatory arthritis. In order to functionally characterize the ECM of synovium, synovial extracellular matrix was purified from pannus removed at joint replacement surgery. A prominent 140 Kd 6M guanidine extractable component was found to mediate synoviocyte adhesion in a cell-blotting assay. This 140 Kd component was identified as a form of type VI collagen. Type VI collagen appears to be a significant component of synovial ECM.