Inhibition of proteoglycan synthesis by transforming growth factor beta in anatomically intact articular cartilage of murine patellae.

The effect of transforming growth factor beta (TGF beta) on proteoglycan synthesis and degradation in anatomically intact articular cartilage of murine patellae was studied. Exogenously added TGF beta up to a concentration of 200 pmol/l had no effect on proteoglycan synthesis in intact articular cartilage. Neutralisation of endogenously produced TGF beta with a specific monoclonal antibody to TGF beta, however, led to stimulation of proteoglycan synthesis, indicating that TGF beta itself inhibits proteoglycan synthesis in anatomically intact cartilage. Transforming growth factor beta decreased the degradation of proteoglycans in intact cartilage in the absence of fetal calf serum or insulin-like growth factor 1. In the presence of fetal calf serum or insulin-like growth factor 1, TGF beta had no additional effect on proteoglycan breakdown.