Soluble mediators of articular cartilage degradation in juvenile rheumatoid arthritis

Juvenile rheumatoid arthritis (JRA) involves a wide range of joint tissues. Tissue changes include proliferation of synovial cells, alterations in synovial fluid, and degradation of articular cartilage. Synovial cell proliferation results in increased numbers of fibroblasts and lymphocytes. Changes in the synovial fluid include increased content of antibodies, altered complement ratios, increased levels of factors stimulating cartilage-mediated proteoglycan degradation, and decreased levels of insulinlike growth factor I. Levels of cytokine such as interleukin-1 and interleukin-2 vary with cell culture and assay technique. Cartilage degradation is apparent from increased quantities of proteoglycan and glycosaminoglycan in serum and synovial fluid. Type II collagen peptide antibodies are also prevalent in JRA patients. Cartilage degradation appears linked to factors in JRA synovial fluid. Conditioned medium of peripheral blood mononuclear cells from patients with JRA also stimulates increased release of cartilage proteoglycan. Thus, the outcome in JRA likely reflects activities of interacting soluble factors that directly influence cartilage homeostasis.