Cytokines in Models of Arthritis

The cytokines IL-1 and TNF cannot by themselves account for the pathology of rheumatoid arthritis (RA) or osteoarthritis. Nonetheless, their actions mimic in detail many processes observed in arthritic disease, and circumstances that could lead to continuous synthesis and release of IL-1 or TNF would be expected to lead to a chronic arthritis. Thus, both IL-1 and TNF could play a significant role in the pathogenesis of arthritis. Moreover, the ability of the cytokines to cause a flare or increase the severity of an arthritis suggest that they would play a role even in arthritis lacking a cytokine etiology if they were induced by concurrent infection or other processes. These models of cytokine-induced arthritis then have value for studies into possible mechanisms of arthritic disease and as tools for design and development of cytokine-directed therapy. Transgenic animals may prove to be a useful tool in understanding the pathogenesis of arthritic diseases by demonstrating the role of cytokines and growth factors. In vitro studies often fail to mimic the full range of physiological and pathological effects that these products have in the whole animal.