Nicotinamide adenine dinucleotide phosphate oxidase in experimental liver fibrosis: GKT137831 as a novel potential therapeutic agent.
Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) generates reactive oxygen species (ROS) in hepatic stellate cells (HSCs) during liver fibrosis. In response to fibrogenic agonists, such as angiotensin II (Ang II), the NOX1 components form an active complex, including Ras-related botulinum toxin substrate 1 (Rac1). Superoxide dismutase 1 (SOD1) interacts with the NOX-Rac1 complex to stimulate NOX activity. NOX4 is also induced in activated HSCs/myofibroblast by increased gene expression. Here, we investigate the role of an enhanced activity SOD1 G37R mutation (SODmu) and the effects of GKT137831, a dual NOX1/4 inhibitor, on HSCs and liver fibrosis. To induce liver fibrosis, wild-type (WT) and SOD1mu mice were treated with CCl(4) or bile duct ligation (BDL). Then, to address the role of NOX-SOD1-mediated ROS production in HSC activation and liver fibrosis, mice were treated with a NOX1/4 inhibitor. Fibrosis and ROS generation was assessed by histology and measurement of thiobarbituric acid reactive substances and NOX-related genes. Primary cultured HSCs isolated from WT, SODmu, and NOX1 knockout (KO) mice were assessed for ROS production, Rac1 activity, and NOX gene expression. Liver fibrosis was increased in SOD1mu mice, and ROS production and Rac1 activity were increased in SOD1mu HSCs. The NOX1/4 inhibitor, GKT137831, attenuated liver fibrosis and ROS production in both SOD1mu and WT mice as well as messenger RNA expression of fibrotic and NOX genes. Treatment with GKT137831 suppressed ROS production and NOX and fibrotic gene expression, but not Rac1 activity, in SOD1mut and WT HSCs. Both Ang II and tumor growth factor beta up-regulated NOX4, but Ang II required NOX1.


CONCLUSIONS
SOD1mu induces excessive NOX1 activation through Rac1 in HSCs, causing enhanced NOX4 up-regulation, ROS generation, and liver fibrosis. Treatment targeting NOX1/4 may be a new therapy for liver fibrosis.
Department of Medicine, University of California San Diego, La Jolla, CA 92093-0602, USA.
Tomonori
T
Aoyama
Yong-Han
YH
Paik
Sumio
S
Watanabe
Benoît
B
Laleu
Francesca
F
Gaggini
Laetitia
L
Fioraso-Cartier
Sophie
S
Molango
Freddy
F
Heitz
Cédric
C
Merlot
Cédric
C
Szyndralewiez
Patrick
P
Page
David A
DA
Brenner
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D015870:Gene Expression; D055166:Hepatic Stellate Cells / Q000187:drug effects; D008103:Liver Cirrhosis / Q000188:drug therapy* / Q000201:enzymology* / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology / Q000627:therapeutic use*; D047069:Pyrazolones; D011725:Pyridines / Q000494:pharmacology / Q000627:therapeutic use*; D011728:Pyridones; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics*; D000072105:Superoxide Dismutase-1; D015854:Up-Regulation; D020744:rac GTP-Binding Proteins / Q000378:metabolism; D020830:rac1 GTP-Binding Protein
D004791:Enzyme Inhibitors; D009479:Neuropeptides; D011720:Pyrazoles; D047069:Pyrazolones; D011725:Pyridines; D011728:Pyridones; D012333:RNA, Messenger; C484602:Rac1 protein, mouse; D017382:Reactive Oxygen Species; D000804:Angiotensin II; C576694:setanaxib; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C000614711:NOX1 protein, mouse; C422943:Nox4 protein, mouse; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein