title: Chronic ethanol consumption in mice alters hepatocyte lipid droplet properties.
abstract: BACKGROUND
  Hepatosteatosis is a common pathological feature of impaired hepatic metabolism following chronic alcohol consumption. Although often benign and reversible, it is widely believed that steatosis is a risk factor for development of advanced liver pathologies, including steatohepatitis and fibrosis. The hepatocyte alterations accompanying the initiation of steatosis are not yet clearly defined.
  
  
  METHODS
  Induction of hepatosteatosis by chronic ethanol consumption was investigated using the Lieber-DeCarli (LD) high fat diet model. Effects were assessed by immunohistochemistry and blood and tissue enzymatic assays. Cell culture models were employed for mechanistic studies.
  
  
  RESULTS
  Pair feeding mice ethanol (LD-Et) or isocaloric control (LD-Co) diets for 6 weeks progressively increased hepatocyte triglyceride accumulation in morphological, biochemical, and zonally distinct cytoplasmic lipid droplets (CLD). The LD-Et diet induced zone 2-specific triglyceride accumulation in large CLD coated with perilipin, adipophilin (ADPH), and TIP47. In LD-Co-fed mice, CLD were significantly smaller than those in LD-Et-fed mice and lacked perilipin. A direct role of perilipin in formation of large CLD was further suggested by cell culture studies showing that perilipin-coated CLD were significantly larger than those coated with ADPH or TIP47. LD-Co- and LD-Et-fed animals also differed in hepatic metabolic stress responses. In LD-Et but not LD-Co-fed mice, inductions were observed in the following: microsomal ethanol-oxidizing system [cytochrome P-4502E1 (CYP2E1)], hypoxia response pathway (hypoxia-inducible factor 1 alpha, HIF1α), endoplasmic reticulum stress pathway (calreticulin), and synthesis of lipid peroxidation products [4-hydroxynonenal (4-HNE)]. CYP2E1 and HIF1 α immunostaining localized to zone 3 and did not correlate with accumulation of large CLD. In contrast, calreticulin and 4-HNE immunostaining closely correlated with large CLD accumulation. Importantly, 4-HNE staining significantly colocalized with ADPH and perilipin on the CLD surface.
  
  
  CONCLUSIONS
  These data suggest that ethanol contributes to macrosteatosis by both altering CLD protein composition and inducing lipid peroxide adduction of CLD-associated proteins.
authors.affiliation: Department of Pathology, University of Colorado Anschutz Medical Campus, 12800 E. 19th Ave., Aurora, CO 80045, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Orlicky
authors.forename: James R
authors.initials: JR
authors.lastname: Roede
authors.forename: Elise
authors.initials: E
authors.lastname: Bales
authors.forename: Carrie
authors.initials: C
authors.lastname: Greenwood
authors.forename: Andrew
authors.initials: A
authors.lastname: Greenberg
authors.forename: Dennis
authors.initials: D
authors.lastname: Petersen
authors.forename: James L
authors.initials: JL
authors.lastname: McManaman
mesh_terms: D000428:Alcohol Drinking / Q000378:metabolism*; D000818:Animals; D002908:Chronic Disease; D003593:Cytoplasm / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage / Q000009:adverse effects / Q000378:metabolism*; D000431:Ethanol / Q000008:administration & dosage* / Q000009:adverse effects; D005235:Fatty Liver, Alcoholic / Q000209:etiology / Q000378:metabolism*; D057809:HEK293 Cells; D022781:Hepatocytes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D050356:Lipid Metabolism / Q000187:drug effects / Q000502:physiology*; D015227:Lipid Peroxidation / Q000187:drug effects / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D014280:Triglycerides / Q000737:chemistry / Q000378:metabolism
chemical_list: D004041:Dietary Fats; D014280:Triglycerides; D000431:Ethanol