DIRECT DEGRADATION OF ARTICULAR-CARTILAGE BY RHEUMATOID SYNOVIAL-FLUID - CONTRIBUTION OF PROTEOLYTIC-ENZYMES

Objective. To test the effects of synovial fluids (SF) on human cartil age in an in vitro model. Methods. Freshly collected SF were incubated with cryostat sections of articular cartilage, and glycosaminoglycan (GAG) loss determined by microdensitometry after alcian blue staining. Results. Of 20 rheumatoid SF, 11 induced significant GAG loss compare d with only 3 out of 15 osteoarthritic SF. The effect of rheumatoid fl uids appeared to be related to disease activity. GAG loss was partiall y prevented by a broad spectrum serine protease inhibitor and a specif ic elastase inhibitor. Cartilage degrading activity was lost on storag e which may explain why it has not been widely reported before. Conclu sion. Rheumatoid SF can directly degrade cartilage through the action of proteases. There is an involvement of serine proteases, elastase in particular.