title: Lipid-induced hepatocyte-derived extracellular vesicles regulate hepatic stellate cell via microRNAs targeting PPAR-γ.
abstract: Hepatic stellate cells (HSCs) play a key role in liver fibrosis in various chronic liver disorders including nonalcoholic fatty liver disease (NAFLD). The development of liver fibrosis requires a phenotypic switch from quiescent to activated HSCs. The triggers for HSCs activation in NAFLD remain poorly understood. We investigated the role and molecular mechanism of extracellular vesicles (EVs) released by hepatocytes during lipotoxicity in modulation of HSC phenotype.
  
  
  METHODS
  EVs were isolated from fat-laden hepatocytes by differential centrifugation and incubated with HSCs. EV internalization and HSCs activation, migration and proliferation were assessed. Loss- and gain-of-functions studies were performed to explore the potential role of PPAR-γ-targeting miRNAs carried by EVs into HSC.
  
  
  RESULTS
  Hepatocyte-derived EVs released during lipotoxicity are efficiently internalized by HSCs resulting in their activation, as shown by marked up-regulation of pro-fibrogenic genes (Collagen-I, α-SMA and TIMP-2), proliferation, chemotaxis and wound healing responses. These changes were associated with miRNAs shuttled by EVs and suppression of PPAR-γ expression in HSC. Hepatocyte-derived EVs miRNA content included various miRNAs that are known inhibitors of PPAR-γ expression with miR-128-3p being the most effectively transferred. Furthermore loss- and gain-of-function studies identified miR-128-3p as a central modulator of the effects of EVs on PPAR-γ inhibition and HSC activation.
  
  
  CONCLUSIONS
  Our findings demonstrate a link between fat-laden hepatocyte-derived EVs and liver fibrosis and have potential implications for the development of novel anti-fibrotic targets for NAFLD and other fibrotic diseases.
authors.affiliation: Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA.
authors.forename: Davide
authors.initials: D
authors.lastname: Povero
authors.affiliation: Hepato-Metabolic Disease Unit and Liver Research Unit, Bambino-Gesu' Children's Hospital, IRCCS, 00165, Roma, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Panera
authors.affiliation: Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA.
authors.forename: Akiko
authors.initials: A
authors.lastname: Eguchi
authors.affiliation: Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA.
authors.forename: Casey D
authors.initials: CD
authors.lastname: Johnson
authors.affiliation: Department of Pathology, VA San Diego Healthcare System, San Diego, CA 92103, USA.
authors.forename: Bettina G
authors.initials: BG
authors.lastname: Papouchado
authors.affiliation: Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA.; Centro Universitário Lusiada, Santos, 11050-071, Brazil.
authors.forename: Lucas
authors.initials: L
authors.lastname: de Araujo Horcel
authors.affiliation: Institute of Biomedical Technologies, National Research Council, 20090, Segrate Milano, Italy.
authors.forename: Eva M
authors.initials: EM
authors.lastname: Pinatel
authors.affiliation: Hepato-Metabolic Disease Unit and Liver Research Unit, Bambino-Gesu' Children's Hospital, IRCCS, 00165, Roma, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Alisi
authors.affiliation: Hepato-Metabolic Disease Unit and Liver Research Unit, Bambino-Gesu' Children's Hospital, IRCCS, 00165, Roma, Italy.
authors.forename: Valerio
authors.initials: V
authors.lastname: Nobili
authors.affiliation: Department of Pediatrics, University of California San Diego, La Jolla, CA 92093, USA.
authors.forename: Ariel E
authors.initials: AE
authors.lastname: Feldstein
keywords: Extracellular Vesicles; Hepatic Stellate Cell; Lipotoxicity; Liver Fibrosis; miRNAs