Effects of phenol on barrier function of a human intestinal epithelial cell line correlate with altered tight junction protein localization

• Type of Material: Article
• Authors: Ingrid C. McCall, Emory University; Abigail Betanzos, Emory University; Dominique A Weber, Emory University; Porfirio Nava, Emory University; Gary W Miller, Emory University; Charles Parkos, Emory University
• Language: English
• Date: 2009-11-15
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2009 Elsevier Inc. All rights reserved.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.taap.2009.08.002
• Title of Journal or Parent Work: Toxicology And Applied Pharmacology
• ISSN: 0041-008X
• Volume: 241
• Issue: 1
• Start Page: 61
• End Page: 70
• Grant/Funding Information: This work was supported by the National Institutes of Health DK72564 and DK61379 (C.A.P), a Digestive Diseases Minicenter grant DK064399 (epithelial cell culture core and microscopy core support), and the Crohn's and Colitis Foundation of America (P. Nava).
• Keywords: Epithelial paracellular barrier; Cell viability; SK-CO15 cells; Phenol; Transepithelial electrical resistance; Tight junctions
• Research Categories: Environmental Sciences; Health Sciences, Occupational Health and Safety; Health Sciences, Pathology

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.