No abstract

Barrier dysfunction has been implicated in the pathophysiology of eosinophilic esophagitis (EoE). TGF-β1, a potent pleiotropic molecule, is increased in EoE, however, no study has evaluated its influence on esophageal epithelial barrier. We hypothesized that TGF-β1 regulates barrier dysfunction in EoE. We aimed to determine the role of TGF-β1 in epithelial barrier in models of EoE. To examine the impact of TGF-β1 on esophageal barrier, immortalized human esophageal epithelial (EPC2-hTERT) cells were exposed to TGF-β1 during the 3-dimensional air liquid interface (3D-ALI) model in vitro. TGF-β1 exposure diminished EPC2-hTERT barrier function as measured by transepithelial electrical resistance (TEER) and 3kDa FITC dextran paracellular flux (FITC Flux) and H&E assessment revealed prominent cellular separation. In analysis of epithelial barrier molecules, TGF-β1 led to the specific reduction in expression of the tight-junction molecule, claudin-7 and this was prevented by TGF-β receptor I inhibitor. shRNA mediated claudin-7 knockdown diminished epithelial barrier function, while claudin-7 overexpression resulted in protection from TGF-β1-mediated barrier dysfunction. In analysis of pediatric EoE biopsies claudin-7 expression was decreased, altered localization was observed by immunofluorescence analysis and the TGF-β1 downstream transcription factor phosphorylated SMAD2/3 (pSMAD2/3) was increased. Our data suggest that TGF-β1 participates in esophageal epithelial barrier dysfunction through claudin-7 dysregulation.

Granulocyte-macrophage colony-stimulating factor is a potential therapeutic target to reduce esophageal eosinophilia and remodeling.

RATIONALE: Eosinophilic esophagitis (EoE), a chronic allergic disease, lacks sensitive and specific peripheral biomarkers. We hypothesized that concentrations of EoE-related biomarkers captured using a 1-hour minimally invasive Esophageal String Test (EST) would correlate with mucosal eosinophil counts and tissueconcentrations of the same biomarkers. We aimed to determine if a 1-hour EST accurately distinguishes active from inactive EoE. METHODS: In a prospective, multi-site study, children and adults (ages 7-55yrs) undergoing a clinically indicated esophagogastroduodenoscopy performed an EST with an esophageal dwell time of 1-hour. Subjects were divided into 4 groups: 1) active EoE, 2) inactive (treated) EoE, 3) GERD and 4) normal esophageal mucosa. Eosinophil-associated proteins were compared between EST effluents and esophageal biopsy extracts. Statistical modeling was performed to select biomarkers that best correlated with eosinophilic inflammation. RESULTS: 143 subjects (96 children, 47 adults) with active EoE (n562), inactive EoE (n537), GERD (n59) and normal esophagus (n535) completed the study; no serious adverse events were recorded. ESTcaptured eosinophil-associated proteins were significantly correlated with peak eosinophils/HPF, endoscopic visual scoring (EREFS), and the same proteins extracted from mucosal biopsies. Statistical modeling, using combined eotaxin-3 and MBP-1 concentrations, led to the development of EoE scores that distinguished between subjects with active EoE compared to inactive EoE in subjects with an EoE diagnosis, and compared to subjects with inactive EoE, GERD or normal esophagi. CONCLUSIONS: The 1-hour EST can be used to accurately distinguish active from inactive disease in children and adults with EoE and facilitate monitoring of EoE disease activity in a safe, minimally invasive fashion.