title: Omeprazole blocks STAT6 binding to the eotaxin-3 promoter in eosinophilic esophagitis cells.
abstract: BACKGROUND
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Internal Medicine, Veterans Affairs North Texas Health Care System and the University of Texas Southwestern Medical Center, Dallas, Texas, United States of America.
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.forename: Edaire
authors.initials: E
authors.lastname: Cheng
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Huo
authors.forename: Chunhua
authors.initials: C
authors.lastname: Yu
authors.forename: Qiuyang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Thai H
authors.initials: TH
authors.lastname: Pham
authors.forename: David H
authors.initials: DH
authors.lastname: Wang
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Spechler
authors.forename: Rhonda F
authors.initials: RF
authors.lastname: Souza
mesh_terms: D018929:Cell Culture Techniques; D000075906:Chemokine CCL26; D019742:Chemokines, CC / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000187:drug effects*; D057765:Eosinophilic Esophagitis / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D004804:Eosinophils / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005744:Gastric Acid / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D015847:Interleukin-4 / Q000008:administration & dosage / Q000378:metabolism; D009853:Omeprazole / Q000008:administration & dosage*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D054328:Proton Pump Inhibitors / Q000008:administration & dosage; D012319:RNA Polymerase II / Q000378:metabolism; D050800:STAT6 Transcription Factor / Q000235:genetics / Q000378:metabolism
chemical_list: C120429:CCL26 protein, human; D000075906:Chemokine CCL26; D019742:Chemokines, CC; D004268:DNA-Binding Proteins; C508598:IL4 protein, human; D054328:Proton Pump Inhibitors; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D015847:Interleukin-4; D012319:RNA Polymerase II; D009853:Omeprazole