Figure 3

13-HODE and 15-HETE downregulate induction of MMP-1/MMP-13 protein synthesis by IL-1β, TNF-α and IL-17. (a, b) Chondrocytes were stimulated with IL-1β (100 pg/ml), (c, d) TNF-α (0.1 ng/ml), or (e, f) IL-17 (10 ng/ml) in the presence of vehicle (dimethyl sulfoxide at a maximum concentration of 0.14%) or increasing concentrations of 13-HODE (panels a, c, and e) or 15-HETE (panels b, d, and f) for 24 hours. The levels of MMP-1 and MMP-13 proteins in conditioned media were measured using ELISA. Results are expressed as the percentage of control, considering 100% as the value of cells treated with IL-1β, TNF-α or IL-17 alone, and are the mean ± standard deviation of at least three independent experiments. *P < 0.05 versus cells treated with IL-1β, TNF-α, or IL-17 alone. HETE, hydroxyeicosatetraenoic acid; HODE, hydroxy octadecadienoic acid; MMP, matrix metalloproteinase; TNF, tumor necrosis factor.