IL6 and rheumatoid arthritis: It protects articular cartilage in models of rheumatoid arthritis [12] and inhibits IL-1 induced increases in MMP-13 in healthy but not OA chondrocytes [13,14]; it also increases nitric oxide, IL-6, reactive oxygen species and prostaglandin E2 (PGE2) release and downregulates collagen and proteoglycans synthesis by chondrocytes [[15], [16], [17]].