Preferential Secretion of Thymic Stromal Lymphopoietin (TSLP) by Terminally Differentiated Esophageal Epithelial Cells: Relevance to Eosinophilic Esophagitis (EoE).

Prasanna M Chandramouleeswaran,Dawen Shen,Benjamin J Wilkins,Jonathan M Spergel,Jennifer H Yearley,Kara Dods,Rene Dewaal Malefyt,Anna J Lee,Amanda B Muir,Sarit Toltzis,Yuliana Noah,Jamie Merves,Hiroshi Nakagawa,Fiona Gambanga,Alain Benitez,Mei-Lun Wang,Taishin Akiyama

doi:10.1371/journal.pone.0150968

Abstract

Eosinophilic esophagitis (EoE) is a chronic Th2 and food antigen-mediated disease characterized by esophageal eosinophilic infiltration. Thymic stromal lymphopoetin (TSLP), an epithelial derived cytokine which bridges innate and Th2-type adaptive immune responses in other allergic conditions, is overexpressed in esophageal biopsies of EoE subjects. However, the triggers of TSLP expression in the esophageal epithelium are unknown. The objective of the current study was to characterize TSLP expression in human esophageal epithelium in EoE in vivo and to determine the role of food antigens upon epithelial TSLP expression in vitro. Using immunohistochemistry (IHC), we localized TSLP in esophageal biopsies of active EoE (≥15 eos/hpf), inactive EoE (<15 eos/hpf) and non-EoE control subjects, and found that TSLP expression was restricted to the differentiated suprabasal layer of the epithelium in actively inflamed EoE biopsies. Consistent with these results in vivo, inducible TSLP protein secretion was higher in CaCl2 differentiated telomerase-immortalized esophageal epithelial cells (EPC2-hTERT) compared to undifferentiated cells of the basal phenotype, following stimulation with the TLR3 ligand poly(I:C). To determine whether food antigens could directly induce epithelial TSLP secretion, differentiated and undifferentiated primary esophageal epithelial cells from EoE and non-EoE subjects were challenged with food antigens clinically relevant to EoE: Chicken egg ovalbumin (OVA), wheat, and milk proteins beta-lactoglobulin (blg) and beta-casein. Food antigens failed to induce TSLP secretion by undifferentiated cells; in contrast, only OVA induced TSLP secretion in differentiated epithelial cells from both EoE and control cell lines, an effect abolished by budesonide and NF-κb inhibition. Together, our study shows that specific food antigens can trigger innate immune mediated esophageal TSLP secretion, suggesting that esophageal epithelial cells at the barrier surface may play a significant role in the pathogenesis of EoE by regulating TSLP expression.

Highlights

Eosinophilic esophagitis (EoE) is a chronic allergic disease characterized by the infiltration of eosinophils into the esophageal epithelium
Our study shows that specific food antigens can trigger innate immune mediated esophageal Thymic stromal lymphopoietin (TSLP) secretion, suggesting that esophageal epithelial cells at the barrier surface may play a significant role in the pathogenesis of EoE by regulating TSLP expression
We have shown that TSLP expression during active EoE is restricted to the suprabasal layer of the esophageal epithelium

Summary

Introduction

Eosinophilic esophagitis (EoE) is a chronic allergic disease characterized by the infiltration of eosinophils into the esophageal epithelium. TSLP is known to drive the inflammatory response in gastrointestinal diseases including celiac disease and inflammatory bowel diseas[4,5] as well as allergic disorders such as asthma[3,6], atopic dermatitis[7] [6], and gastrointestinal allergy[8,9]. Consistent with its role in allergic disorders, TSLP is overexpressed in esophageal biopsies from EoE subjects[10,11] and polymorphisms in TSLP were recently identified in association with EoE[12]. We recently described a mouse model of EoE-like disease in which esophageal eosinophilic infiltration and subsequent esophageal food impactions were dependent upon TSLP and basophils[11]

Objectives

Methods

Results

Conclusion