title: Effects of phenol on barrier function of a human intestinal epithelial cell line correlate with altered tight junction protein localization.
abstract: Phenol contamination of soil and water has raised concerns among people living near phenol-producing factories and hazardous waste sites containing the chemical. Phenol, particularly in high concentrations, is an irritating and corrosive substance, making mucosal membranes targets of toxicity in humans. However, few data on the effects of phenol after oral exposure exist. We used an in vitro model employing human intestinal epithelial cells (SK-CO15) cultured on permeable supports to examine effects of phenol on epithelial barrier function. We hypothesized that phenol disrupts epithelial barrier by altering tight junction (TJ) protein expression. The dose-response effect of phenol on epithelial barrier function was determined using transepithelial electrical resistance (TER) and FITC-dextran permeability measurements. We studied phenol-induced changes in cell morphology and expression of several tight junction proteins by immunofluorescence and Western blot analysis. Effects on cell viability were assessed by MTT, Trypan blue, propidium iodide and TUNEL staining. Exposure to phenol resulted in decreased TER and increased paracellular flux of FITC-dextran in a dose-dependent manner. Delocalization of claudin-1 and ZO-1 from TJs to cytosol correlated with the observed increase in permeability after phenol treatment. Additionally, the decrease in TER correlated with changes in the distribution of a membrane raft marker, suggesting phenol-mediated effects on membrane fluidity. Such observations were independent of effects of phenol on cell viability as enhanced permeability occurred at doses of phenol that did not cause cell death. Overall, these findings suggest that phenol may affect transiently the lipid bilayer of the cell membrane, thus destabilizing TJ-containing microdomains.
authors.affiliation: Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA. icmccal@emory.edu
authors.forename: Ingrid C
authors.initials: IC
authors.lastname: McCall
authors.forename: Abigail
authors.initials: A
authors.lastname: Betanzos
authors.forename: Dominique A
authors.initials: DA
authors.lastname: Weber
authors.forename: Porfirio
authors.initials: P
authors.lastname: Nava
authors.forename: Gary W
authors.initials: GW
authors.lastname: Miller
authors.forename: Charles A
authors.initials: CA
authors.lastname: Parkos
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003911:Dextrans / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D017097:Electric Impedance; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics; D010539:Permeability; D019800:Phenol / Q000008:administration & dosage / Q000633:toxicity*; D012989:Soil Pollutants / Q000008:administration & dosage / Q000633:toxicity*; D019108:Tight Junctions / Q000187:drug effects* / Q000378:metabolism; D014873:Water Pollutants / Q000008:administration & dosage / Q000633:toxicity*
chemical_list: D003911:Dextrans; D008565:Membrane Proteins; D012989:Soil Pollutants; D014873:Water Pollutants; C015219:fluorescein isothiocyanate dextran; D019800:Phenol; D016650:Fluorescein-5-isothiocyanate
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