The role of cytokines and growth factors in cartilage destruction in osteoarthritis and rheumatoid arthritis.

Cartilage destruction in arthritis and osteoarthritis is linked to aberrant cytokine and growth factor expression in the affected tissues. It becomes clear that the balance of protective and destructive cytokines is more important for the net destruction than the absolute levels of destructive mediators. IL-1 is a key destructive mediator in arthritis and probably also in osteoarthritis. Production of the cartilage destructive enzyme stromelysin is linked to IL-1. In osteoarthritis, excessive formation of the growth factor TGF beta may contribute to cartilage lesions and osteophyte formation, in particular. Therapy should be aimed at neutralization of IL-1 and stimulation of safe anabolic growth factors for the articular cartilage, such as IGF-1 and the novel bone and cartilage derived morphogenetic proteins.