Role of cytokines in osteoarthritis: comparative effects of interleukin 1 and transforming growth factor-beta on cultured rabbit articular chondrocytes.

: Monolayer culture of rabbit articular chondrocytes has been used to study the effects of transforming growth factor-beta (TGF-beta) and interleukin 1 (IL-1) on the production of matrix components, particularly collagens and proteoglycans. TGF-beta was shown to stimulate synthesis of collagen types II and XI as well as that of proteoglycans. The factor increases steady state level of procollagens I, II and III mRNA. Proteoglycans produced in the presence of TGF-beta had the same hydrodynamic sizes as those of controls, but a decrease of the ratio of chondroiting 6-sulfate: chondroitin 4-sulfate was observed. It was shown that TGF-beta may counteract the effect of IL-1 on synthesis of both collagen and proteoglycan and production of metalloproteases when it is introduced after IL-1, while it does not prevent the effect of the monokine when it is first added to the cultures.