title: Angiotensin II protects primary rat hepatocytes against bile salt-induced apoptosis.
abstract: Angiotensin II (AT-II) is a pro-fibrotic compound that acts via membrane-bound receptors (AT-1R/AT-2R) and thereby activates hepatic stellate cells (HSCs). AT-II receptor blockers (ARBs) are thus important candidates in the treatment of liver fibrosis. However, multiple case reports suggest that AT-1R blockers may induce hepatocyte injury. Therefore, we investigated the effect of AT-II and its receptor blockers on cytokine-, oxidative stress- and bile salt-induced cell death in hepatocytes. Primary rat hepatocytes were exposed to TNF-α/Actinomycin D, the ROS-generating agent menadione or the bile salts: glycochenodeoxycholic acid (GCDCA) and tauro-lithocholic acid-3 sulfate (TLCS), to induce apoptosis. AT-II (100 nmol/L) was added 10 minutes prior to the cell death-inducing agent. AT-1R antagonists (Sartans) and the AT-2R antagonist PD123319 were used at 1 µmol/L. Apoptosis (caspase-3 activity, acridine orange staining) and necrosis (Sytox green staining) were quantified. Expression of CHOP (marker for ER stress) and AT-II receptor mRNAs were quantified by Q-PCR. AT-II dose-dependently reduced GCDCA-induced apoptosis of hepatocytes (-50%, p<0.05) without inducing necrosis. In addition, AT-II reduced TLCS-induced apoptosis of hepatocytes (-50%, p<0.05). However, AT-II did not suppress TNF/Act-D and menadione-induced apoptosis. Only the AT-1R antagonists abolished the protective effect of AT-II against GCDCA-induced apoptosis. AT-II increased phosphorylation of ERK and a significant reversal of the protective effect of AT-II was observed when signaling kinases, including ERK, were inhibited. Moreover, AT-II prevented the GCDCA-induced expression of CHOP (the marker of the ER-mediated apoptosis).
  
  
  CONCLUSIONS
  Angiotensin II protects hepatocytes from bile salt-induced apoptosis through a combined activation of PI3-kinase, MAPKs, PKC pathways and inhibition of bile salt-induced ER stress. Our results suggest a mechanism for the observed hepatocyte-toxicity of Sartans (angiotensin receptor blockers, ARBs) in some patients with chronic liver injury.
authors.affiliation: Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. g.karimian01@umcg.nl
authors.forename: Golnar
authors.initials: G
authors.lastname: Karimian
authors.forename: Manon
authors.initials: M
authors.lastname: Buist-Homan
authors.forename: Bojana
authors.initials: B
authors.lastname: Mikus
authors.forename: Robert H
authors.initials: RH
authors.lastname: Henning
authors.forename: Klaas Nico
authors.initials: KN
authors.lastname: Faber
authors.forename: Han
authors.initials: H
authors.lastname: Moshage
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D048430:Cell Shape / Q000187:drug effects; D002478:Cells, Cultured; D003609:Dactinomycin / Q000494:pharmacology; D059865:Endoplasmic Reticulum Stress; D004789:Enzyme Activation; D005999:Glycochenodeoxycholic Acid / Q000494:pharmacology* / Q000502:physiology; D022781:Hepatocytes / Q000187:drug effects / Q000502:physiology*; D020935:MAP Kinase Signaling System; D008297:Male; D018384:Oxidative Stress; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D061251:Primary Cell Culture; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism; D013658:Taurolithocholic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology / Q000502:physiology; D024483:Vitamin K 3 / Q000494:pharmacology
chemical_list: D017382:Reactive Oxygen Species; D044140:Receptor, Angiotensin, Type 1; D014409:Tumor Necrosis Factor-alpha; D000804:Angiotensin II; C066776:taurolithocholic acid 3-sulfate; D003609:Dactinomycin; D013658:Taurolithocholic Acid; D005999:Glycochenodeoxycholic Acid; D024483:Vitamin K 3; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; C505410:Casp3 protein, rat; D053148:Caspase 3