... degradation exceeds synthesis. The balance between synthesis and degradation is affected by age and is regulated by several factors produced by the synovium and chondrocytes, including cytokines, growthfactors, ... stimulated by the proinflammatorycytokines IL-1 and TNF-α [2 9–3 1,36]. NO may be involvedin cartilage catabolism by inhibiting the synthesis of colla-gen and PG, enhancing MMP activity, reducing the ... othercytokines (e.g. IL-8, IL-6, and leukotriene inhibitory factor),proteases, and prostaglandin E2(PGE2) [30]. Synthesis of the inflammatory cytokines IL-1 and TNF-α and expression of their...