Figure 7.

Effect of prostaglandin D₂ (PGD₂) on interleukin-1-beta (IL-1β)-induced upregulation of lipocalin-type prostaglandin D synthase (L-PGDS) expression. Osteoarthritis chondrocytes were pretreated with increasing concentrations of PGD₂ for 30 minutes prior to stimulation with IL-1β (100 pg/mL). After 48 hours, cell lysates were prepared and analyzed for L-PGDS and β-actin protein expression by Western blotting. A representative Western blot is shown in the upper panel. In the lower panel, the bands were scanned, and the L-PGDS band intensity values were normalized to the corresponding β-actin band intensity value. Data are expressed as fold induction, considering 1 as the value of unstimulated cells, and represent the mean ± standard error of the mean of four independent experiments. *P < 0.05 compared with cells stimulated with IL-1β alone.