title: The receptor TGR5 protects the liver from bile acid overload during liver regeneration in mice.
abstract: Many regulatory pathways are involved in liver regeneration after partial hepatectomy (PH) to initiate growth, protect liver cells, and sustain functions of the remnant liver. Bile acids (BAs), whose levels rise in the blood early after PH, stimulate both hepatocyte proliferation and protection, in part through their binding to the nuclear farnesoid X receptor (FXR). However, the effect of the BA receptor, TGR5 (G-protein-coupled BA receptor 1) after PH remains to be studied. Liver histology, hepatocyte proliferation, BA concentrations (plasma, bile, liver, urine, and feces), bile flow and composition, and cytokine production were studied in wild-type (WT) and TGR5 KO (knockout) mice before and after PH. BA composition (plasma, bile, liver, urine, and feces) was more hydrophobic in TGR5 KO than in WT mice. After PH, severe hepatocyte necrosis, prolonged cholestasis, exacerbated inflammatory response, and delayed regeneration were observed in TGR5 KO mice. Although hepatocyte adaptive response to post-PH BA overload was similar in WT and TGR5 KO mice, kidney and biliary adaptive responses were strongly impaired in TGR5 KO mice. Cholestyramine treatment, as well as Kupffer cell depletion, significantly improved the post-PH TGR5 KO mice phenotype. After bile duct ligation or upon a cholic acid-enriched diet, TGR5 KO mice exhibited more severe liver injury than WT as well as impaired BA elimination in urine.
  
  
  CONCLUSIONS
  TGR5 is crucial for liver protection against BA overload after PH, primarily through the control of bile hydrophobicity and cytokine secretion. In the absence of TGR5, intrahepatic stasis of abnormally hydrophobic bile and excessive inflammation, in association with impaired bile flow adaptation and deficient urinary BA efflux, lead to BA overload-induced liver injury and delayed regeneration.
authors.affiliation: INSERM U.757, Université Paris Sud, Orsay, France; Université Paris Sud, Orsay, France; Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
authors.forename: Noémie
authors.initials: N
authors.lastname: Péan
authors.forename: Isabelle
authors.initials: I
authors.lastname: Doignon
authors.forename: Isabelle
authors.initials: I
authors.lastname: Garcin
authors.forename: Aurore
authors.initials: A
authors.lastname: Besnard
authors.forename: Boris
authors.initials: B
authors.lastname: Julien
authors.forename: Bingkaï
authors.initials: B
authors.lastname: Liu
authors.forename: Sophie
authors.initials: S
authors.lastname: Branchereau
authors.forename: Anne
authors.initials: A
authors.lastname: Spraul
authors.forename: Catherine
authors.initials: C
authors.lastname: Guettier
authors.forename: Lydie
authors.initials: L
authors.lastname: Humbert
authors.forename: Kristina
authors.initials: K
authors.lastname: Schoonjans
authors.forename: Dominique
authors.initials: D
authors.lastname: Rainteau
authors.forename: Thierry
authors.initials: T
authors.lastname: Tordjmann
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000009:adverse effects* / Q000378:metabolism*; D049109:Cell Proliferation; D002792:Cholestyramine Resin / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D006498:Hepatectomy; D006505:Hepatitis / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D008099:Liver / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D008115:Liver Regeneration / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009336:Necrosis; D010641:Phenotype; D043562:Receptors, G-Protein-Coupled / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
chemical_list: D001647:Bile Acids and Salts; D016207:Cytokines; C513561:Gpbar1 protein, mouse; D043562:Receptors, G-Protein-Coupled; D002792:Cholestyramine Resin