Chronic inflammation of the esophagus due to gastroesophageal reflux disease (GERD) contributes to the development of Barrett's esophagus and esophageal adenocarcinoma, a lethal tumor whose incidence has been rising at an alarming rate. Modern medical therapy of GERD is directed almost exclusively at decreasing gastric acid production with medications such as proton pump inhibitors (PPIs). In GERD patients taking PPIs, weakly acidic gastric juice frequently refluxes into the esophagus. Perhaps this is why PPIs do not completely eliminate GERD symptoms in up to 40% of patients, and why the frequency of esophageal adenocarcinoma continues to rise despite the widespread use of PPIs. New medical treatments are needed to improve GERD symptom control, and to prevent the development of Barrett's esophagus and esophageal adenocarcinoma. In a rat model of reflux esophagitis in which an esophago-duodenostomy is created to induce reflux, we recently studied the early histological events in the development of reflux esophagitis, and found a sequence suggesting that this esophagitis develops through a cytokine-mediated injury rather than through an acid burn. Based on these experiments, we proposed a new concept for the development of reflux esophagitis in which the reflux of gastric juice stimulates esophageal squamous epithelial cells to secrete cytokines that induce proliferative changes and attract inflammatory cells, and it is those inflammatory changes, not the caustic effects of acid, that ultimately damage the esophageal mucosa. Hypoxia, a common feature of chronically inflamed tissues, contributes to inflammation through the regulation of HIFs, a family of transcription factors that allow cells to respond to hypoxic stress. Recently, in a mouse model of colitis caused by a genetically-engineered increase in HIF-2? signaling in colonic epithelial cells, colitis was shown to develop in a pattern virtually identical to that which we observed in our rat model of reflux esophagitis. In addition, we have preliminary data demonstrating that exposure to a weakly acidic bile salt solution activates HIF-2? signaling in esophageal epithelial cells. Therefore, we hypothesize that esophageal secretion of pro-inflammatory cytokines and esophageal epithelial cell proliferation result from reflux-induced activation of HIF-2?.
The aims of this study are (1) to elucidate the mechanisms whereby acid and bile salts activate HIF-2?, (2) to determine the role of HIF-2? in acid and bile salt-induced expression of pro-inflammatory cytokines and epithelial cell proliferation in esophageal squamous cells in vitro, and (3) to elaborate the early histological events in the pathogenesis of reflux esophagitis in the esophagus of patients with GERD, and to correlate those events with esophageal expression of HIF-2? and pro-inflammatory cytokines, and with changes in esophageal proliferation.

Public Health Relevance

to public health is that understanding the early pathophysiology of gastroesophageal reflux disease (GERD) at the cellular and molecular levels is essential if new medical treatments are to be developed to improve GERD symptom control, to eliminate esophageal inflammation, and to prevent the development of Barrett's esophagus and esophageal adenocarcinoma.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK063621-12
Application #
8467706
Study Section
Special Emphasis Panel (ZRG1-DKUS-C (03))
Program Officer
Hamilton, Frank A
Project Start
2002-09-30
Project End
2016-07-31
Budget Start
2013-08-01
Budget End
2014-07-31
Support Year
12
Fiscal Year
2013
Total Cost
$264,459
Indirect Cost
$54,571
Name
University of Texas Sw Medical Center Dallas
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
800771545
City
Dallas
State
TX
Country
United States
Zip Code
75390
Asanuma, Kiyotaka; Huo, Xiaofang; Agoston, Agoston et al. (2016) In oesophageal squamous cells, nitric oxide causes S-nitrosylation of Akt and blocks SOX2 (sex determining region Y-box 2) expression. Gut 65:1416-26
Wang, David H; Souza, Rhonda F (2016) Transcommitment: Paving the Way to Barrett's Metaplasia. Adv Exp Med Biol 908:183-212
Dunbar, Kerry B; Agoston, Agoston T; Odze, Robert D et al. (2016) Association of Acute Gastroesophageal Reflux Disease With Esophageal Histologic Changes. JAMA 315:2104-12
Naini, Bita V; Souza, Rhonda F; Odze, Robert D (2016) Barrett's Esophagus: A Comprehensive and Contemporary Review for Pathologists. Am J Surg Pathol 40:e45-66
Souza, Rhonda F (2016) From Reflux Esophagitis to Esophageal Adenocarcinoma. Dig Dis 34:483-90
Nadatani, Yuji; Huo, Xiaofang; Zhang, Xi et al. (2016) NOD-Like Receptor Protein 3 Inflammasome Priming and Activation in Barrett's Epithelial Cells. Cell Mol Gastroenterol Hepatol 2:439-453
Yu, Chunhua; Huo, Xiaofang; Agoston, Agoston T et al. (2015) Mitochondrial STAT3 contributes to transformation of Barrett's epithelial cells that express oncogenic Ras in a p53-independent fashion. Am J Physiol Gastrointest Liver Physiol 309:G146-61
Chakraborty, Sharmistha; Li, Li; Puliyappadamba, Vineshkumar Thidil et al. (2014) Constitutive and ligand-induced EGFR signalling triggers distinct and mutually exclusive downstream signalling networks. Nat Commun 5:5811
Zhang, Qiuyang; Yu, Chunhua; Peng, Sui et al. (2014) Autocrine VEGF signaling promotes proliferation of neoplastic Barrett's epithelial cells through a PLC-dependent pathway. Gastroenterology 146:461-72.e6
Park, Jason Y; Zhang, Xi; Nguyen, Nathalie et al. (2014) Proton pump inhibitors decrease eotaxin-3 expression in the proximal esophagus of children with esophageal eosinophilia. PLoS One 9:e101391

Showing the most recent 10 out of 60 publications