Adiponectin enhances NO, IL-6, MMP-1 and MMP-3 production in human primary chondrocytes in a dose-dependent manner. Chondrocytes obtained from patients with osteoarthritis (OA) were treated with increasing concentrations of adiponectin (0.1 to 3 μg/ml). Concentrations of NO (A), IL-6 (B), matrix metalloproteinase 1 (MMP-1) (C) and MMP-3 (D) were measured by the Griess reaction and ELISA in the culture medium after 24-hour incubation. The figure shows the results of a representative experiment which was repeated three times (that is, with cells from three donors) with similar results. Results are expressed as means ± SEM (n = 4). *P < 0.05 and ***P < 0.001 compared to the control sample.