MMP3 and osteoarthritis: Recent studies have shown that HA plays an important role in joint lubrication, protects articular cartilage from damage, and acts as a biological inhibitor of inflammation and degradation of joints by down-regulating gene expression of osteoarthritis-associated enzymes, such as MMP-3 in fibroblast-like synoviocytes [42], and inhibiting MMP-1 and MMP-3 production by RSFs [43, 44].