TNF and osteoarthritis: Both IL-2 and IL-7 have been mentioned to lead a pro-inflammatory role in the progress of osteoarthritis, as well as IL-1 and Tumor Necrosis Factor (TNF)-α have been shown to enhance the production of proteolytic enzymes in early OA, leading to fundamental changes in the extracellular matrix which leads to chondrocyte proliferation,stimulated collagen and proteoglycans biosynthesis corresponding to a repair attempt (Hulejová et al. 2007, Zangerle et al. 1992).