Synergistic effect of l-ascorbic acid and hyaluronic acid on the expressions of matrix metalloproteinase-3 and −9 in human chondrocytes

Proinflammatory cytokines and reactive oxygen species (ROS) are known to be involved in the initiation and progression of osteoarthritis (OA). New evidence clarifying the correlation between ROS and inflammation has indicated that oxidative stress can up-regulate inflammatory cytokines. l-Ascorbic acid (AA), an antioxidant, has been shown to have anti-inflammatory effects and improve matrix deposition in chondrocytes. The purpose of this study was to examine the effects of hyaluronic acid (HA; 100 μg/mL) supplemented with AA (50 μg/mL) on human normal and interleukin-1 beta-stimulated (IL-1β, 10 ng/mL) chondrocytes. HA, AA, and HA+AA treatment did not change cell morphology, viability, proliferation, and glycosaminoglycan production in normal chondrocytes. HA, AA, and HA+AA, by contrast, partially restored viability and morphology of hypertrophic chondrocytes, and HA and HA+AA further decreased the cytotoxicity of IL-1β. Real-time PCR revealed that AA and HA+AA had no substantial effects on unstimulated chondrocytes, except for down-regulation of matrix metalloproteinase (MMP)-9 mRNA levels. For IL-1β-stimulated chondrocytes, significant down-regulation of IL-1β, tumor necrosis factor-alpha (TNF-α), MMP-3, and MMP-9 mRNA expression was found when cells were cultured in HA-supplemented media. Moreover, HA+AA supplementation further significantly decreased MMP-3 and MMP-9 mRNA expression. The protein production of MMP-3 was decreased, with a significant difference between the HA+AA group and HA group. The antioxidant capacity and superoxide dismutases activity were also partially restored in stimulated chondrocytes. HA supplemented with AA modulates MMPs expression and antioxidant fuction in chondrocytes. AA may enhance the anticatabolic effects of HA on OA chondrocytes.