title: Hormesis in Cholestatic Liver Disease; Preconditioning with Low Bile Acid Concentrations Protects against Bile Acid-Induced Toxicity.
abstract: BACKGROUND
  Cholestasis is characterized by accumulation of bile acids and inflammation, causing hepatocellular damage. Still, liver damage markers are highest in acute cholestasis and drop when this condition becomes chronic, indicating that hepatocytes adapt towards the hostile environment. This may be explained by a hormetic response in hepatocytes that limits cell death during cholestasis.
  
  
  OBJECTIVE
  To investigate the mechanisms that underlie the hormetic response that protect hepatocytes against experimental cholestatic conditions.
  
  
  METHODS
  HepG2.rNtcp cells were preconditioned (24 h) with sub-apoptotic concentrations (0.1-50 μM) of various bile acids, the superoxide donor menadione, TNF-α or the Farsenoid X Receptor agonist GW4064, followed by a challenge with the apoptosis-inducing bile acid glycochenodeoxycholic acid (GCDCA; 200 μM for 4 h), menadione (50 μM, 6 h) or cytokine mixture (CM; 6 h). Levels of apoptotic and necrotic cell death, mRNA expression of the bile salt export pump (ABCB11) and bile acid sensors, as well as intracellular GCDCA levels were analyzed.
  
  
  RESULTS
  Preconditioning with the pro-apoptotic bile acids GCDCA, taurocholic acid, or the protective bile acids (tauro)ursodeoxycholic acid reduced GCDCA-induced caspase-3/7 activity in HepG2.rNtcp cells. Bile acid preconditioning did not induce significant levels of necrosis in GCDCA-challenged HepG2.rNtcp cells. In contrast, preconditioning with cholic acid, menadione or TNF-α potentiated GCDCA-induced apoptosis. GCDCA preconditioning specifically reduced GCDCA-induced cell death and not CM- or menadione-induced apoptosis. The hormetic effect of GCDCA preconditioning was concentration- and time-dependent. GCDCA-, CDCA- and GW4064- preconditioning enhanced ABCB11 mRNA levels, but in contrast to the bile acids, GW4064 did not significantly reduce GCDCA-induced caspase-3/7 activity. The GCDCA challenge strongly increased intracellular levels of this bile acid, which was not lowered by GCDCA-preconditioning.
  
  
  CONCLUSIONS
  Sub-toxic concentrations of bile acids in the range that occur under normal physiological conditions protect HepG2.rNtcp cells against GCDCA-induced apoptosis, which is independent of FXR-controlled changes in bile acid transport.
authors.affiliation: Department of Gastroenterology and Hepatology, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Esther M
authors.initials: EM
authors.lastname: Verhaag
authors.affiliation: Department of Gastroenterology and Hepatology, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.|Department of Laboratory Medicine, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Manon
authors.initials: M
authors.lastname: Buist-Homan
authors.affiliation: Department of Laboratory Medicine, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Martijn
authors.initials: M
authors.lastname: Koehorst
authors.affiliation: Department of Laboratory Medicine, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.|Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Albert K
authors.initials: AK
authors.lastname: Groen
authors.affiliation: Department of Gastroenterology and Hepatology, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.|Department of Laboratory Medicine, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Han
authors.initials: H
authors.lastname: Moshage
authors.affiliation: Department of Gastroenterology and Hepatology, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.|Department of Laboratory Medicine, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Klaas Nico
authors.initials: KN
authors.lastname: Faber
mesh_terms: D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D017209:Apoptosis / Q000187:drug effects; D001647:Bile Acids and Salts / Q000494:pharmacology* / Q000633:toxicity*; D002779:Cholestasis / Q000139:chemically induced* / Q000150:complications / Q000473:pathology / Q000517:prevention & control*; D016207:Cytokines / Q000378:metabolism; D019610:Cytoprotection / Q000187:drug effects; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D059165:Hormesis; D006801:Humans; D007555:Isoxazoles / Q000494:pharmacology; D008107:Liver Diseases / Q000150:complications*; D017382:Reactive Oxygen Species / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists / Q000378:metabolism; D013997:Time Factors; D015533:Transcriptional Activation / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D024483:Vitamin K 3 / Q000494:pharmacology; D000099150:Receptor, Farnesoid X-Activated
chemical_list: D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters; D001647:Bile Acids and Salts; D016207:Cytokines; D007555:Isoxazoles; D017382:Reactive Oxygen Species; D018160:Receptors, Cytoplasmic and Nuclear; D014409:Tumor Necrosis Factor-alpha; D024483:Vitamin K 3; D000099150:Receptor, Farnesoid X-Activated; C093491:ABCB11 protein, human; C412815:GW 4064