High molecular weight hyaluronic acid inhibits IL-6-induced MMP production from human chondrocytes by up-regulating the ERK inhibitor, MKP-1

► IL-6 induces MMP-1, MMP-3 and MMP-13 via ERK1/2 signaling in chondrocytes. ► HA inhibits MMP induction by IL-6. ► HA induces MKP-1, negative regulator of ERK1/2. ► MKP-1 induced by HA blocks production of MMP.