title: Effects of ethanol and acetaldehyde on tight junction integrity: in vitro study in a three dimensional intestinal epithelial cell culture model.
abstract: BACKGROUND
  Intestinal barrier dysfunction and translocation of endotoxins are involved in the pathogenesis of alcoholic liver disease. Exposure to ethanol and its metabolite, acetaldehyde at relatively high concentrations have been shown to disrupt intestinal epithelial tight junctions in the conventional two dimensional cell culture models. The present study investigated quantitatively and qualitatively the effects of ethanol at concentrations detected in the blood after moderate ethanol consumption, of its metabolite acetaldehyde and of the combination of both compounds on intestinal barrier function in a three-dimensional cell culture model.
  
  
  RESULTS
  Caco-2 cells were grown in a basement membrane matrix (Matrigel™) to induce spheroid formation and were then exposed to the compounds at the basolateral side. Morphological differentiation of the spheroids was assessed by immunocytochemistry and transmission electron microscopy. The barrier function was assessed by the flux of FITC-labeled dextran from the basal side into the spheroids' luminal compartment using confocal microscopy. Caco-2 cells grown on Matrigel assembled into fully differentiated and polarized spheroids with a central lumen, closely resembling enterocytes in vivo and provide an excellent model to study epithelial barrier functionality. Exposure to ethanol (10-40 mM) or acetaldehyde (25-200 µM) for 3 h, dose-dependently and additively increased the paracellular permeability and induced redistribution of ZO-1 and occludin without affecting cell viability or tight junction-encoding gene expression. Furthermore, ethanol and acetaldehyde induced lysine residue and microtubules hyperacetylation.
  
  
  CONCLUSIONS
  These results indicate that ethanol at concentrations found in the blood after moderate drinking and acetaldehyde, alone and in combination, can increase the intestinal epithelial permeability. The data also point to the involvement of protein hyperacetylation in ethanol- and acetaldehyde-induced loss of tight junctions integrity.
authors.affiliation: Top Institute Food and Nutrition, Wageningen, The Netherlands.
authors.forename: Elhaseen
authors.initials: E
authors.lastname: Elamin
authors.forename: Daisy
authors.initials: D
authors.lastname: Jonkers
authors.forename: Kati
authors.initials: K
authors.lastname: Juuti-Uusitalo
authors.forename: Sven
authors.initials: S
authors.lastname: van Ijzendoorn
authors.forename: Freddy
authors.initials: F
authors.lastname: Troost
authors.forename: Hans
authors.initials: H
authors.lastname: Duimel
authors.forename: Jos
authors.initials: J
authors.lastname: Broers
authors.forename: Fons
authors.initials: F
authors.lastname: Verheyen
authors.forename: Jan
authors.initials: J
authors.lastname: Dekker
authors.forename: Ad
authors.initials: A
authors.lastname: Masclee
mesh_terms: D000079:Acetaldehyde / Q000494:pharmacology*; D000107:Acetylation / Q000187:drug effects; D018938:Caco-2 Cells; D018929:Cell Culture Techniques; D002463:Cell Membrane Permeability / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects*; D000431:Ethanol / Q000494:pharmacology*; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D007422:Intestines / Q000166:cytology; D008565:Membrane Proteins / Q000378:metabolism; D062793:Occludin; D010750:Phosphoproteins / Q000378:metabolism; D012997:Solvents / Q000494:pharmacology; D018874:Spheroids, Cellular / Q000473:pathology; D019108:Tight Junctions / Q000187:drug effects* / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism; D062826:Zonula Occludens-1 Protein
chemical_list: D005456:Fluorescent Dyes; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D010750:Phosphoproteins; D012997:Solvents; C569042:TJP1 protein, human; D014404:Tubulin; D062826:Zonula Occludens-1 Protein; D000431:Ethanol; D000079:Acetaldehyde