title: ASMase regulates autophagy and lysosomal membrane permeabilization and its inhibition prevents early stage non-alcoholic steatohepatitis.
abstract: OBJECTIVE
  Acid sphingomyelinase (ASMase) is activated in non-alcoholic steatohepatitis (NASH). However, the contribution of ASMase to NASH is poorly understood and limited to hepatic steatosis and glucose metabolism. Here we examined the role of ASMase in high fat diet (HFD)-induced NASH.
  
  
  METHODS
  Autophagy, endoplasmic reticulum (ER) stress and lysosomal membrane permeabilization (LMP) were determined in ASMase(-/-) mice fed a HFD. The impact of pharmacological ASMase inhibition on NASH was analyzed in wild type mice fed a HFD.
  
  
  RESULTS
  ASMase deficiency determined resistance to hepatic steatosis mediated by a HFD or methionine-choline deficient diet. ASMase(-/-) mice were resistant to HFD-induced hepatic ER stress, but sensitive to tunicamycin-mediated ER stress, indicating selectivity in the resistance of ASMase(-/-) mice to ER stress and steatosis. Autophagic flux, determined in the presence of rapamycin and/or chloroquine, was lower in primary mouse hepatocytes (PMH) from ASMase(-/-) mice and accompanied by increased p62 levels, suggesting autophagic impairment. Moreover, autophagy suppression by chloroquine and brefeldin A caused ER stress in PMH from ASMase(+/+) mice but not in ASMase(-/-) mice. ASMase(-/-) PMH exhibited increased lysosomal cholesterol loading, decreased LMP and apoptosis resistance induced by O-methyl-serine dodecylamide hydrochloride or palmitic acid, effects that were reversed by decreasing cholesterol levels by oxysterol 25-hydroxycholesterol. In vivo pharmacological ASMase inhibition by amitriptyline, a widely used tricyclic antidepressant, protected wild type mice against HFD-induced hepatic steatosis, fibrosis, and liver damage, effects indicative of early-stage NASH.
  
  
  CONCLUSIONS
  These findings underscore a critical role for ASMase in diet-induced NASH and suggest the potential of amitriptyline as a treatment for patients with NASH.
authors.affiliation: Department of Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, IDIBAPS Hospital Clinic de Barcelona and CIBEREHD, Barcelona, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Fucho
authors.affiliation: Department of Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, IDIBAPS Hospital Clinic de Barcelona and CIBEREHD, Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Martínez
authors.affiliation: Department of Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, IDIBAPS Hospital Clinic de Barcelona and CIBEREHD, Barcelona, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Baulies
authors.affiliation: Department of Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, IDIBAPS Hospital Clinic de Barcelona and CIBEREHD, Barcelona, Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Torres
authors.affiliation: Department of Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, IDIBAPS Hospital Clinic de Barcelona and CIBEREHD, Barcelona, Spain.
authors.forename: Nuria
authors.initials: N
authors.lastname: Tarrats
authors.affiliation: Department of Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, IDIBAPS Hospital Clinic de Barcelona and CIBEREHD, Barcelona, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Fernandez
authors.affiliation: Department of Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, IDIBAPS Hospital Clinic de Barcelona and CIBEREHD, Barcelona, Spain.
authors.forename: Vicente
authors.initials: V
authors.lastname: Ribas
authors.affiliation: Institute of Molecular Biology and Genetics CSIC, Medical School, University of Valladolid and CIBERDEM, Valladolid, Spain.
authors.forename: Alma M
authors.initials: AM
authors.lastname: Astudillo
authors.affiliation: Institute of Molecular Biology and Genetics CSIC, Medical School, University of Valladolid and CIBERDEM, Valladolid, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Balsinde
authors.affiliation: Diabetes and Obesity Laboratory, IDIBAPS-Hospital Clinic de Barcelona, Barcelona, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Garcia-Rovés
authors.affiliation: Biochemical Service, Hospital Clinic de Barcelona, Barcelona, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Elena
authors.affiliation: Department of Nutritional Sciences, Friedrich-Schiller-University, Jena, Germany.
authors.forename: Ina
authors.initials: I
authors.lastname: Bergheim
authors.affiliation: Université Paris-Est, UMR-S955, UPEC, Créteil, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Lotersztajn
authors.affiliation: Department of Internal Medicine III, University Hospital, RWTH Aachen, Aachen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Trautwein
authors.affiliation: Experimental Pathology, Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Hanna
authors.initials: H
authors.lastname: Appelqvist
authors.affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Australia.
authors.forename: Adrienne W
authors.initials: AW
authors.lastname: Paton
authors.affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Australia.
authors.forename: James C
authors.initials: JC
authors.lastname: Paton
authors.affiliation: Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, United States.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Czaja
authors.affiliation: Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.
authors.forename: Neil
authors.initials: N
authors.lastname: Kaplowitz
authors.affiliation: Department of Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, IDIBAPS Hospital Clinic de Barcelona and CIBEREHD, Barcelona, Spain; Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States. Electronic address: checa229@yahoo.com.
authors.forename: Jose C
authors.initials: JC
authors.lastname: Fernandez-Checa
authors.affiliation: Department of Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, IDIBAPS Hospital Clinic de Barcelona and CIBEREHD, Barcelona, Spain; Southern California Research Center for ALPD and Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States. Electronic address: cgrbam@iibb.csic.es.
authors.forename: Carmen
authors.initials: C
authors.lastname: García-Ruiz
mesh_terms: D000639:Amitriptyline / Q000494:pharmacology; D000818:Animals; D001343:Autophagy / Q000502:physiology*; D002518:Ceramides / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D002796:Choline Deficiency / Q000150:complications; D059305:Diet, High-Fat / Q000009:adverse effects; D004195:Disease Models, Animal; D059865:Endoplasmic Reticulum Stress; D006801:Humans; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008247:Lysosomes / Q000378:metabolism; D008715:Methionine / Q000172:deficiency; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D065626:Non-alcoholic Fatty Liver Disease / Q000201:enzymology* / Q000209:etiology / Q000517:prevention & control*; D010539:Permeability; D013108:Sphingomyelin Phosphodiesterase / Q000037:antagonists & inhibitors* / Q000172:deficiency / Q000378:metabolism*; D013109:Sphingomyelins / Q000378:metabolism
chemical_list: D002518:Ceramides; D013109:Sphingomyelins; D000639:Amitriptyline; D002784:Cholesterol; D008715:Methionine; C577975:ASMase, mouse; D013108:Sphingomyelin Phosphodiesterase
keywords: Autophagy; Ceramide; Endoplasmic reticulum stress; Fatty liver; Lysosomal membrane permeabilization