title: Indomethacin suppresses LAMP-2 expression and induces lipophagy and lipoapoptosis in rat enterocytes via the ER stress pathway.
abstract: BACKGROUND
  Indomethacin enhances small intestinal epithelial cell apoptosis, which may account for mucosal ulceration. However, the involvement of autophagy in indomethacin-induced enterocyte damage is unreported.
  
  
  METHODS
  Using light microscopy and electron microscopy techniques, Western blot analysis, and pharmacological inhibition of autophagy, we investigated the autophagic response of cultured rat enterocytes to indomethacin treatment (200 µM) at various time points. Furthermore, autophagy was examined in enterocytes of rats given indomethacin by gavage (10 mg/kg).
  
  
  RESULTS
  Our data indicate that indomethacin induced accumulation of cytoplasmic lipid droplets (LDs) in cultured enterocytes, which was associated with time-dependent autophagic responses. Initially (0-6 h), mediated by endoplasmic reticulum stress and suppression of mammalian target of rapamycin, a predominant cytoprotective lipophagy was activated in indomethacin-treated enterocytes, as evidenced by induction and colocalization of LC3-II with LDs, excessive formation of autophagosomes sequestering LDs (autolipophagosomes; ALPs), and decreased viability of enterocytes on blocking autophagy with 3-methyladenine. On prolonged exposure to indomethacin (6-24 h), there was a decrease of LAMP-2 expression in enterocytes coupled with accumulation of ALPs and LDs with fewer autolysosomes in addition to an elevation of lipoapoptosis. These time-dependent autophagic and apoptotic responses to indomethacin treatment were detected in enterocytes of indomethacin-treated rats, confirming in vitro results.
  
  
  CONCLUSIONS
  The findings of this study describe a novel mechanism of enterocyte damage by indomethacin mediated by endoplasmic reticulum stress, accumulation of LDs, and subsequent activation of the early phase of cytoprotective lipophagy. This is followed by a late phase characterized by reduced expression of lysosomal autophagic proteins, accumulation of ALPs, and enhanced lipoapoptosis.
authors.affiliation: Second Department of Internal Medicine, Osaka Medical College, Daigakumachi, Takatsuki, Osaka, 569-8686, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Narabayashi
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ito
authors.forename: Nabil
authors.initials: N
authors.lastname: Eid
authors.forename: Kentaro
authors.initials: K
authors.lastname: Maemura
authors.forename: Takuya
authors.initials: T
authors.lastname: Inoue
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Takeuchi
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Otsuki
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Higuchi
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D001343:Autophagy / Q000187:drug effects* / Q000235:genetics; D002478:Cells, Cultured; D059865:Endoplasmic Reticulum Stress / Q000235:genetics; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects*; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology*; D050356:Lipid Metabolism; D052119:Lysosomal-Associated Membrane Protein 2 / Q000187:drug effects* / Q000235:genetics; D008297:Male; D023421:Models, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D052119:Lysosomal-Associated Membrane Protein 2; D007213:Indomethacin