ABSTRACT
Cytokines include interleukins, tumor necrosis factors (TNFs), interferons, colony stimulating factors, and certain growth factors. They have paracine, autocrine, and endocrine actions, and many of them regulate the behavior of a range of cell types. The two cytokines which have the most important effects on cartilage matrix are interleukin 1 (IL-1) and tumor necrosis factor (TNF). This chapter focuses on the roles of other cytokines, particularly with regard to modulation of the actions of IL-1 and TNF. Culture with cytokines had little early effect on the collagenous matrix of the cartilage, but some collagen breakdown was observed on prolonged culture with IL-1. More recently, it has been found that lipophilic inhibitors of cysteine proteinases will inhibit IL-1-induced degradation in bovine nasal septum cartilage in organ culture. The kinases activated by the cytokines in fibroblasts mainly phosphorylate serine and possibly threonine, and are distinct from protein kinase C or cAMP-dependent kinase.
