Preventive effects of hyaluronan on bone resorption

<p>Hyaluronan (HA) is a large glycosaminoglycan which exists in the human body as a component of the extra-cellular matrices. HA is an essential molecule for matrix assembly and fluid viscosity in cartilage. Currently, intraarticular injection of HA is widely used for the treatment of pain in the rheumatoid arthritis and osteoarthritis, however, the roles of HA in bone metabolism remain unknown. We have reported that HA showed the inhibitory effects on inflammatory bone resorption. HA inhibited interleukin (IL)-1-induced bone resorbing activity associated with decreasing the production of matrix metalloproteinase (MMP)-2 and -9 in organ cultures of mouse calvariae. In cocultures of mouse primary osteoblasts and bone marrow cells, HA suppressed IL-1-induced osteoclast differentiation. Mechanistically, in osteoblasts, HA blocked PG (prostaglandin) E2 production through the downregulating mRNA expression of cyclooxygenase (COX)-2, membrane-bound PGE synthase (mPGES)-1, receptor activator of NF-κB ligand (RANKL), and MMP-13. We further demonstrated that HA attenuates NF-κB transcriptional activity in osteoblasts. In this review, we summarized the recent studies regarding the roles of HA in bone tissues as the preventive component for bone resorption. HA could be a one of the candidates for maintaining bone health.</p>