Figure 1.

The effect of leptin on NO production (a), iNOS protein expression (b), PGE₂ production (c), COX-2 protein expression (d), IL-6 production (e), and IL-8 production (f) in human OA cartilage. Cartilage explants were incubated with leptin (0.1 μg/mL or 10 μg/mL) for 48 hours. NO production (a) was measured as nitrite accumulation in the culture medium by Griess reaction. Expression of iNOS protein (b) and COX-2 protein (d) were measured by Western blot. PGE₂ production (c) in the culture medium was measured by RIA. Concentrations of IL-6 (e), and IL-8 (f) in the culture medium were measured by ELISA. Results are expressed as pmol/mg cartilage (a), as percentages in comparison with control sample ((b) and (d)) or pg/mg cartilage ((c), (e), and (f)). Values are mean ± SEM. Samples were collected from 6 patients (n = 6) in (a) and (c), from 3 patients (n = 3) in (b) and (d), and from 7 patients (n = 7) in (e) and (f). #: P < .2, ∗: P < .05, and ∗ ∗: P < .01 as compared to control explants incubated in absence of exogenous leptin.