title: Liver fibrosis and hepatocyte apoptosis are attenuated by GKT137831, a novel NOX4/NOX1 inhibitor in vivo.
abstract: Reactive oxygen species (ROS) play a key role in chronic liver injury and fibrosis. Homologs of NADPH oxidases (NOXs) are major sources of ROS, but the exact role of the individual homologs in liver disease is unknown. Our goal was to determine the role of NOX4 in liver fibrosis induced by bile duct ligation (BDL) with the aid of the pharmacological inhibitor GKT137831, and genetic deletion of NOX4 in mice. GKT137831 was either applied for the full term of BDL (preventive arm) or started at 10 day postoperatively (therapeutic arm). Primary hepatic stellate cells (HSC) from control mice with and without BDL were analyzed and the effect of NOX4 inhibition on HSC activation was also studied. FasL or TNFα/actinomycin D-induced apoptosis was studied in wild-type and NOX4(-/-) hepatocytes. NOX4 was upregulated by a TGF-β/Smad3-dependent mechanism in HSC. Downregulation of NOX4 decreased ROS production and the activation of NOX4(-/-) HSC was attenuated. NOX4(-/-) hepatocytes were more resistant to FasL or TNFα/actinomycin D-induced apoptosis. Similarly, after pharmacological NOX4 inhibition, ROS production, the expression of fibrogenic markers, and hepatocyte apoptosis were reduced. NOX4 was expressed in human livers with stage 2-3 autoimmune hepatitis. Fibrosis was attenuated by the genetic deletion of NOX4. BDL mice gavaged with GKT137831 in the preventive or the therapeutic arm displayed less ROS production, significantly attenuated fibrosis, and decreased hepatocyte apoptosis. In conclusion, NOX4 plays a key role in liver fibrosis. GKT137831 is a potent inhibitor of fibrosis and hepatocyte apoptosis; therefore, it is a promising therapeutic agent for future translational studies.
authors.affiliation: Department of Internal Medicine, UC Davis, Sacramento, CA, USA.
authors.forename: Joy X
authors.initials: JX
authors.lastname: Jiang
authors.forename: Xiangling
authors.initials: X
authors.lastname: Chen
authors.forename: Nobuko
authors.initials: N
authors.lastname: Serizawa
authors.forename: Cédric
authors.initials: C
authors.lastname: Szyndralewiez
authors.forename: Patrick
authors.initials: P
authors.lastname: Page
authors.forename: Katrin
authors.initials: K
authors.lastname: Schröder
authors.forename: Ralf P
authors.initials: RP
authors.lastname: Brandes
authors.forename: Sridevi
authors.initials: S
authors.lastname: Devaraj
authors.forename: Natalie J
authors.initials: NJ
authors.lastname: Török
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001652:Bile Ducts / Q000187:drug effects / Q000378:metabolism / Q000601:surgery; D003609:Dactinomycin / Q000494:pharmacology; D053222:Fas Ligand Protein / Q000494:pharmacology; D017353:Gene Deletion; D055166:Hepatic Stellate Cells / Q000166:cytology / Q000187:drug effects; D019693:Hepatitis, Autoimmune / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D022781:Hepatocytes / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D006801:Humans; D008026:Ligation; D008099:Liver / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D008103:Liver Cirrhosis / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D051379:Mice; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology* / Q000627:therapeutic use; D047069:Pyrazolones; D011725:Pyridines / Q000494:pharmacology* / Q000627:therapeutic use; D011728:Pyridones; D051381:Rats; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051900:Smad3 Protein / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D011720:Pyrazoles; D047069:Pyrazolones; D011725:Pyridines; D011728:Pyridones; D017382:Reactive Oxygen Species; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D016212:Transforming Growth Factor beta; D003609:Dactinomycin; C576694:setanaxib; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C000614711:NOX1 protein, mouse; C000614712:NOX1 protein, rat; C422943:Nox4 protein, mouse