Proinflammatory effect of visfatin/Nampt and effect of its enzymatic blockade by APO866 on murine chondrocytes. Murine chondrocytes were pretreated or not with 10 nM APO866 for 4 hours, and then with 100 nM recombinant visfatin/nicotinamide phosphoribosyltransferase (Nampt). (A) Quantitative reverse transcriptase-polymerase chain reaction analysis of mRNA levels of interleukin (IL)-6, keratinocyte chemoattractant (Kc) and monocyte chemoattractant protein 1 (MCP-1) relative to that of hypoxanthine–guanine phosphoribosyltransferase, n = 6. (B) Enzyme-linked immunosorbent assay of protein release of IL-6, Kc and MCP-1, n = 6. *P < 0.05 versus nonstimulated control; †P < 0.05 versus visfatin/Nampt alone. The percentage corresponds to the average decrease of mRNA or protein level with APO866 pretreatment. Data are mean ± standard error of the mean of six experiments.