New developments in the role of cytokines and chemokines in inflammatory myopathies.

Cytokines and chemokines are important molecules in the inflammatory response and in immune regulation. Investigations of the production of these molecules in the target organ of inflammation is of particular interest to obtain increased knowledge of the pathogenesis of chronic inflammatory disorders. By investigations of muscle tissue from patients with polymyositis, inclusion-body myositis (IBM), and dermatomyositis a predominance of the cytokines interleukin-1 alpha and -1 beta and transforming growth factor beta was observed. Among the chemokines investigated, macrophage inflammatory protein 1 alpha was the most commonly found molecule. A similar pattern of cytokines and chemokines was present in polymyositis, IBM, and dermatomyositis. This was also true for the pronounced interleukin-1 alpha expression in the endothelial cells of capillaries and venules. The results of these studies suggest a major role of the proinflammatory cytokines interleukin-1 alpha and -1 beta and the importance of the endothelial cells in the pathogenesis not only in dermatomyositis, as previously suggested, but also in polymyositis and IBM. Furthermore, the pronounced interleukin-1 expression in the inflammatory myopathies makes this molecule an interesting potential target for development of future therapies for these disorders.