Omeprazole blocks STAT6 binding to the eotaxin-3 promoter in eosinophilic esophagitis cells

• Published in: PloS one 2012-11, Vol.7 (11), p.e50037
• Main Authors: Zhang, Xi, Cheng, Edaire, Huo, Xiaofang, Yu, Chunhua, Zhang, Qiuyang, Pham, Thai H, Wang, David H, Spechler, Stuart J, Souza, Rhonda F
• Format: Article
• Language: English
• Subjects: Acidification; Acids; Asthma; Autoimmune diseases; Binding; Biology; Biopsy; Blood diseases; Cancer; Care and treatment; Cell Culture Techniques; Chemokine CCL26; Chemokines, CC - biosynthesis; Chemokines, CC - genetics; Chemokines, CC - metabolism; Cytokines; Disease; DNA-Binding Proteins - drug effects; DNA-directed RNA polymerase; Dysphagia; Enzyme-linked immunosorbent assay; Eosinophilia; Eosinophilic Esophagitis - drug therapy; Eosinophilic Esophagitis - metabolism; Eosinophilic Esophagitis - pathology; Eosinophils - cytology; Eosinophils - drug effects; Eosinophils - metabolism; Eotaxin; Esophageal diseases; Esophagitis; Esophagus; Gastric Acid - metabolism; Gastroesophageal reflux; Gastrointestinal diseases; Gene expression; Gene Expression Regulation - drug effects; Humans; Inflammation; Interleukin 4; Interleukin-4 - administration & dosage; Interleukin-4 - metabolism; Internal medicine; Lansoprazole; Leukocytes (eosinophilic); Lymphocytes T; Medicine; Messenger RNA; Molecular modelling; mRNA stability; Nuclear transport; Omeprazole; Omeprazole - administration & dosage; Patients; Phosphorylation; Production methods; Promoter Regions, Genetic - drug effects; Proton pump inhibitors; Proton Pump Inhibitors - administration & dosage; Ribonucleic acid; RNA; RNA polymerase; RNA polymerase II; RNA Polymerase II - metabolism; Squamous cells; Stat6 protein; STAT6 Transcription Factor - genetics; STAT6 Transcription Factor - metabolism; Telomerase; Translocation; Ulcers; Veterans; Western blotting
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0050037

Patients who have esophageal eosinophilia without gastroesophageal reflux disease (GERD) nevertheless can respond to proton pump inhibitors (PPIs), which can have anti-inflammatory actions independent of effects on gastric acid secretion. In esophageal cell cultures, omeprazole has been reported to inhibit Th2 cytokine-stimulated expression of eotaxin-3, an eosinophil chemoattractant contributing to esophageal eosinophilia in eosinophilic esophagitis (EoE). The objective of this study was to elucidate molecular mechanisms underlying PPI inhibition of IL-4-stimulated eotaxin-3 production by esophageal cells. Telomerase-immortalized and primary cultures of esophageal squamous cells from EoE patients were treated with IL-4 in the presence or absence of acid-activated omeprazole or lansoprazole. We measured eotaxin-3 protein secretion by ELISA, mRNA expression by PCR, STAT6 phosphorylation and nuclear translocation by Western blotting, eotaxin-3 promoter activation by an exogenous reporter construct, and STAT6, RNA polymerase II, and trimethylated H3K4 binding to the endogenous eotaxin-3 promoter by ChIP assay. Omeprazole in concentrations ≥5 µM significantly decreased IL-4-stimulated eotaxin-3 protein secretion and mRNA expression. Lansoprazole also blocked eotaxin-3 protein secretion. Omeprazole had no effect on eotaxin-3 mRNA stability or on STAT6 phosphorylation and STAT6 nuclear translocation. Rather, omeprazole blocked binding of IL-4-stimulated STAT6, RNA polymerase II, and trimethylated H3K4 to the eotaxin-3 promoter. PPIs, in concentrations achieved in blood with conventional dosing, significantly inhibit IL-4-stimulated eotaxin-3 expression in EoE esophageal cells and block STAT6 binding to the promoter. These findings elucidate molecular mechanisms whereby patients with Th2 cytokine-driven esophageal eosinophilia can respond to PPIs, independent of effects on gastric acid secretion.