Objective: To test the effects of synovial fluids (SF) on human cartilage 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 compared with only 3 out of 15 osteoarthritic SF. The effect of rheumatoid fluids appeared to be related to disease activity. GAG loss was partially prevented by a broad spectrum serine protease inhibitor and a specific elastase inhibitor. Cartilage degrading activity was lost on storage which may explain why it has not been widely reported before.
Conclusion: Rheumatoid SF can directly degrade cartilage through the action of proteases. There is an involvement of serine proteases, elastase in particular.