Osteopontin is an extracellular scaffold protein that is upregulated in OA cartilage and inhibits IL-1β–induced NO and PGE2 production in human OA–affected cartilage in response to joint inflammation.79 It has been shown that exposure to HA significantly increases osteopontin expression in fibroblast-like synoviocytes from patients with OA of the knee, thus potentially amplifying its anti-inflammatory actions.80 Here, SPP1 is linked to Arthritis.