[Cytokines, growth factors and inflammation]

Cytokines are polypeptides which are usually produced by cells with phagocytic properties and able to present antigens. Some of these biological factors, especially interleukin-1 (IL1) are implicated in inflammatory phenomena at the level of the joints. Especially, the mechanisms of degeneration of the joint cartilage seem to be induced by IL1 secretion in the synovium. Two other cytokines could play a major role in inflammatory phenomena: interferon alpha and the "tumor necrosis factor" (TNF). Beside these molecules, an increasingly larger place must be made for mediator growth factors controlling the proliferation, differentiation and survival of eucaryotic cells. The presence of some of these mediators has been demonstrated in the joints; for others, it is probable, but not effectively proven at this time. In view of these new data, the mechanism of action of NSAIDs must form the subject of additional research. It is actually accepted that their mode of action depends essentially on the inhibition of prostaglandin production. It is not excluded that some NSAIDs may act upon other cellular functions as indicated in several studies. It was demonstrated that naproxen (Naprosyne 500) seems to antagonize the inhibiting action of IL1 on the production of collagen, the main component of cartilage. This effect could be beneficial for the treatment of pathological joint cartilages.