Abstract:
The effect of statins on heme oxygenase-1 (HO-1) was compared in 2 murine cell lines, RAW 264.7 and J774A.1 cell lines, and in primary peritoneal macrophages of BALB-c or C57BL-6 mice. The role of endogenous nitric oxide and the type of transcription factors involved were explored. Simvastatin and fluvastatin induced HO-1. Pretreatment of cells with l-NMMA or 1400 W, two different nitric oxide synthase inhibitors, partially blocked statin-dependent induction of HO-1 in RAW 264.7 and J774A.1 but not in primary peritoneal macrophages. Induction of HO-1 by statins was dependent on p-38 MAP kinase activation in all types of macrophages. In RAW 264.7 cells, both statins increased the activity of reporter genes linked to the proximal 1.3 kbp promoter of HO-1 (EC50 of 1.4±0.3 μM for simvastatin and 0.6±0.03 μM for fluvastatin). This effect was significantly blocked by 1400 W (80±5.2percent inhibition, pandlt;0.02) and mevalonate, the direct metabolite of HMGCoA reductase. Gel retardation experiments implicated C-EBPβ, AP-1 but not USF, for both RAW 264.7 and primary peritoneal macrophages of C57BL-6 mice. Collectively we showed a differential role of endogenous nitric oxide between macrophage cell lines and primary macrophages and an effect of statins in the protection against inflammation by increasing HO-1 expression. © 2013 Mouawad et al.