NADPH oxidase signal transduces angiotensin II in hepatic stellate cells and is critical in hepatic fibrosis

Angiotensin II (Ang II) is a pro-oxidant and fibrogenic cytokine.We investigated the role of NADPH oxidase in Ang II-induced effects in hepatic stellate cells (HSCs), a fibrogenic cell type.Human HSCs express mRNAs of key components of nonphagocytic NADPH oxidase.Ang II phosphorylated p47 phox , a regulatory subunit of NADPH oxidase, and induced reactive oxygen species formation via NADPH oxidase activity.Ang II phosphorylated AKT and MAPKs and increased AP-1 DNA binding in a redox-sensitive manner.Ang II stimulated DNA synthesis, cell migration, procollagen α1(I) mRNA expression, and secretion of TGF-β1 and inflammatory cytokines.These effects were attenuated by N-acetylcysteine and diphenylene iodonium, an NADPH oxidase inhibitor.Moreover, Ang II induced upregulation of genes potentially involved in hepatic wound-healing response in a redoxsensitive manner, as assessed by microarray analysis.HSCs isolated from p47 phox-/-mice displayed a blunted response to Ang II compared with WT cells.We also assessed the role of NADPH oxidase in experimental liver fibrosis.After bile duct ligation, p47 phox-/-mice showed attenuated liver injury and fibrosis compared with WT counterparts.Moreover, expression of smooth muscle α-actin and expression of TGF-β1 were reduced in p47 phox-/-mice.Thus, NADPH oxidase mediates the actions of Ang II on HSCs and plays a critical role in liver fibrogenesis.