Telmisartan reduces interleukin-1 beta (IL-1β)-induced NADPH oxidase activation, reactive oxygen species formation and IL-1 receptor 1 (IL-1R1) mRNA expression in SK-N-SH neuroblasts. (A) Untreated SK-N-SH cells were analyzed for mRNA expression of different NADPH oxidase isoforms. NADPH oxidase-4 (NOX-4) is the dominant isoform of NADPH oxidase in SK-N-SH neuroblasts. The picture shows visualized products of a RT-PCR reaction after separation in an agarose gel. (B,C) Telmisartan reduced IL-1β-induced NOX-4 mRNA expression and NADPH oxidase activity. The cells pretreated with 10 μmol/l telmisartan (Telm) for 2 hours, were incubated with 10 ng/ml IL-1β for 3 hours to determine (B) NOX-4 mRNA expression and (C) NADPH oxidase activity. (D) Telmisartan reduced IL-1β-induced reactive oxygen species (ROS) generation to a lesser extent than does diphenyleneiodonium (DPI). The cells were pretreated with 10 μmol/l Telm or 5 μmol/l DPI for 2 hours before 1 hours exposure to 10 ng/ml IL-1β to determine ROS generation. (E,F) DPI dose-dependently inhibited IL-1β-induced PGE2 release with a potency similar to telmisartan. The cells pretreated with indicated concentrations of DPI or Telm for 2 hour were incubated with IL-1β for 24 hours to determine cumulative PGE2 release. (G) Both telmisartan and DPI reduce hydrogen peroxide-induced COX-2 mRNA expression. The cells were pretreated with 10 μmol/l Telm or 5 μmol/l DPI for 2 hours before exposure for 3 hours to 100 μmol/l hydrogen peroxide (H2O2) to determine COX-2 mRNA expression. (H) Both telmisartan and DPI reduce IL-1β-induced expression of IL-1β receptor IL-1R1 mRNA. The cells were pretreated with 10 μmol/l Telm or 5 μmol/l DPI for 2 hours before exposure for 3 hours to 10 ng/ml IL-1β to determine IL-1R1 mRNA expression. Results are presented as a percentage of Veh. All results are means ± SEM from at least three independent experiments. * P < 0.05, ** P < 0.01, *** P < 0.001 vs. IL-1β or H2O2; ### P < 0.001 vs. Veh.