NADPH oxidase signal transduces angiotensin II in hepatic stellate cells and is critical in hepatic fibrosis
Ramón Bataller, … , John J. Lemasters, David A. Brenner
Ramón Bataller, … , John J. Lemasters, David A. Brenner
Published November 1, 2003
Citation Information: J Clin Invest. 2003;112(9):1383-1394. https://doi.org/10.1172/JCI18212.
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Article Hepatology

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

Abstract

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 p47phox, 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 redox-sensitive manner, as assessed by microarray analysis. HSCs isolated from p47phox–/– 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, p47phox–/– 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 p47phox–/– mice. Thus, NADPH oxidase mediates the actions of Ang II on HSCs and plays a critical role in liver fibrogenesis.

Authors

Ramón Bataller, Robert F. Schwabe, Youkyung H. Choi, Liu Yang, Yong Han Paik, Jeffrey Lindquist, Ting Qian, Robert Schoonhoven, Curt H. Hagedorn, John J. Lemasters, David A. Brenner

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Figure 7

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p47phox–/– mice are protected from liver fibrosis after bile duct ligati...
p47phox–/– mice are protected from liver fibrosis after bile duct ligation for 2 weeks. Representative photomicrographs of bile duct–ligated liver sections processed for Masson’s trichrome (a and b) and Sirius red staining (c and d). p47phox+/+ mice developed extensive periportal damage, necrotic areas around biliary tracts, bile duct proliferation, and bridging fibrosis (a and c). All these lesions were markedly attenuated in p47phox–/– mice (b and d). (e) Quantitation of the area stained for Sirius red. *P < 0.05 vs. p47phox–/– mice; ‡P < 0.05 vs. bile duct–ligated WT mice. n = 5. (f) Hydroxyproline content in sham-operated and bile duct–ligated livers. *P < 0.05 vs. sham operation; ‡P < 0.05 vs. bile duct ligation in p47phox–/–; n = 5. Immunodetection of smooth muscle α-actin in bile duct–ligated liver sections from p47phox+/+ (g) and p47phox–/– mice (h) and TGF-β1 in bile duct–ligated liver sections from p47phox+/+ (i) and p47phox–/– mice (j). p47phox–/– mice showed decreased staining for both smooth muscle α-actin and TGF-β1 compared with p47phox+/+ mice. Original magnifications were ×40, a–d; and ×100, g–j. (k) Quantification of smooth muscle α-actin (α-SMA) content in liver tissues by Western blotting. Relative expression is shown beneath each lane. The figure is representative of three independent experiments.