Identification of ANO1 as a key driver of esophageal epithelial proliferation in eosinophilic esophagitis

Abstract Background The pathology of eosinophilic esophagitis (EoE) is characterized by eosinophil-rich inflammation, basal zone hyperplasia (BZH), dilated intercellular spaces (DIS) and the underlying processes that drive the pathological manifestations of disease remain largely unexplored. Objective To investigate the involvement of calcium activated chloride channel Anoctamin 1 (ANO1) in esophageal proliferation and the histopathologic features of EoE. Methods We examined mRNA and protein expression of ANO1 in esophageal biopsy samples from EoE individuals and in mice with EoE. We performed molecular and cellular analyses and ion transport assays on an in vitro esophageal epithelial 3-dimensional model system (EPC2-ALI) and murine models of EoE to define the relationship between expression and function of ANO1 and esophageal epithelial proliferation in EoE. Results We observed increased ANO1 expression in esophageal biopsies from patients with EoE and in mice with EoE. ANO1 was expressed within the esophageal basal zone and expression positively correlated with disease severity (Eos/HPF) and basal zone hyperplasia (BZH). Employing an in vitro esophageal epithelial 3D model system revealed that ANO1 undergoes chromatin modification and rapid upregulation of expression following IL-13 stimulation; that ANO1 is the primary apical IL-13-induced Cl- transport mechanism within the esophageal epithelium and that loss of ANO1-dependent Cl- transport abrogated esophageal epithelial proliferation. Mechanistically, ANO1-dependent regulation of basal cell proliferation was associated with modulation of TP63 expression and pCdk2 levels. Conclusions These data identify a functional role for ANO1 in esophageal cell proliferation and BZH in EoE, and provides rationale for pharmacological intervention of ANO1 function in EoE.