Figure 5.

Silica induced PGE₂ production is dependent upon increased COX-2 expression. Suspensions of crystalline (CS) and amorphous silica (AS) and either a non-selective COX inhibitor, indomethacin (20 μM) or a selective COX-2 inhibitor, SC58125 (5 μM) were applied to fibroblasts in culture. IL-1β (10 ng/ml), a cytokine that is known to stimulate COX-2, is used as a positive control. Cell supernatants were harvested after 48 h and PGE₂ levels measured using a specific enzyme immunoassay (EIA). Both indomethacin and SC58125 independently attenuated the increase in PGE₂ seen with CS (*p<0.005) and AS (**p<0.001). Data represent mean ± SEM of 6 samples per condition.