LEP and juvenile idiopathic arthritis: These cytokines contribute to the dysregulation of adipocytokine metabolism, including adiponectin and leptin, as well as extracellular matrix components, such as tenascin C. While it is known that children with JIA exhibit TNF-α-stimulated degradation of most ECM cartilage components, the effect of TNF-α antagonists, such as etanercept, on these processes has not yet been evaluated.