Bile salts disrupt human esophageal squamous epithelial barrier function by modulating tight junction proteins.

Abstract

Reflux of acid and bile acids contributes to epithelial tissue injury in gastro-esophageal reflux disease. However, the influence of refluxed material on human esophageal stratified epithelial barrier function and tight junction (TJ) proteins has not been fully elucidated. Here, we investigated the influence of acid and bile acids on barrier function and TJ protein distribution using a newly developed air-liquid interface (ALI) in vitro culture model of stratified squamous epithelium based on primary human esophageal epithelial cells (HEECs). Under ALI conditions, HEECs formed distinct epithelial layers on Transwell inserts after 7 days of culture. The epithelial layers formed TJ, and the presence of claudin-1, claudin-4, and occludin were detected by immunofluorescent staining. The NP-40-insoluble fraction of these TJ proteins was significantly higher by day 7 of ALI culture. Exposure of HEECs to pH 2, and taurocholic acid (TCA) and glycocholic acid (GCA) at pH 3, but not pH 4, for 1 h decreased transepithelial electrical resistance (TEER) and increased paracellular permeability. Exposure of cell layers to GCA (pH 3) and TCA (pH 3) for 1 h also markedly reduced the insoluble fractions of claudin-1 and -4. We found that deoxycholic acid (pH 7.4 or 6, 1 h) and pepsin (pH 3, 24 h) significantly decreased TEER and increased permeability. Based on these findings, ALI-cultured HEECs represent a new in vitro model of human esophageal stratified epithelium and are suitable for studying esophageal epithelial barrier functions. Using this model, we demonstrated that acid, bile acids, and pepsin disrupt squamous epithelial barrier function partly by modulating TJ proteins. These results provide new insights into understanding the role of TJ proteins in esophagitis.

• Authors: Xin Chen, Tadayuki Oshima, Jing Shan, Hirokazu Fukui, Jiro Watari, Hiroto Miwa
• Journal: American journal of physiology. Gastrointestinal and liver physiology (Am J Physiol Gastrointest Liver Physiol) Vol. 303 Issue 2 Pg. G199-208 (Jul 15 2012) ISSN: 1522-1547 [Electronic] United States
• PMID: 22575221 (Publication Type: Journal Article)

Chemical References

• Bile Acids and Salts
• CLDN1 protein, human
• CLDN4 protein, human
• Claudin-1
• Claudin-4
• Claudins
• Gastrointestinal Agents
• Membrane Proteins
• OCLN protein, human
• Occludin
• Deoxycholic Acid
• Pepsin A

Topics

• Bile Acids and Salts (metabolism, pharmacology)
• Cells, Cultured
• Claudin-1
• Claudin-4
• Claudins (analysis, metabolism)
• Deoxycholic Acid (metabolism, pharmacology)
• Electric Impedance
• Epithelium (drug effects, metabolism)
• Esophagus (drug effects, metabolism)
• Gastrointestinal Agents (pharmacology)
• Humans
• Hydrogen-Ion Concentration
• Membrane Proteins (analysis, metabolism)
• Occludin
• Pepsin A (pharmacology)
• Tight Junctions (drug effects, metabolism)