Metabolic dysfunction mediated by HIF-1α contributes to epithelial differentiation defects in eosinophilic esophagitis

Abstract

Investigating the contributory role that epithelial cell metabolism plays in allergic inflammation is a key factor to understanding what influences dysfunction and the pathogenesis of the allergic disease eosinophilic esophagitis (EoE). We previously highlighted the absence of hypoxia signaling through HIF-1α in EoE contributes to esophageal epithelial dysfunction. However, metabolic regulation by HIF-1α has not been explored in esophageal allergy. Herein, we sought to define the role of HIF-1α-mediated metabolic dysfunction in esophageal epithelial differentiation processes and barrier function in EoE. In RNA-sequencing derived from EoE patient biopsies, we observed the expression pattern of key genes involved in mitochondrial metabolism/oxidative phosphorylation (OXPHOS) and glycolysis. Bioenergetics analysis using Seahorse was performed on EPC2-hTERT cells to decipher the metabolic processes involved in epithelial differentiation processes. In addition, air-liquid interface cultures were employed to delineate metabolic dependency mechanisms required for epithelial differentiation. Transcriptomic analysis identified an increase in genes associated with OXPHOS in patients with EoE. Epithelial origin of this signature was confirmed by complex V immunofluorescence of patient biopsies. Bioenergetic analysis in vitro revealed that differentiated epithelium was less reliant on OXPHOS compared with undifferentiated epithelium. Increased OXPHOS potential and reduced glycolytic capacity was mirrored in HIF1A-knockdown EPC2-hTERT cells which portray a significant absence of terminal markers of epithelial differentiation, including involucrin. Pharmacological glucose transport inhibition phenocopied this, while rescue of the HIF-1α-deficient phenotype using the pan-prolyl hydroxylase inhibitor DMOG resulted in restored expression of epithelial differentiation markers. An OXPHOS-dominated metabolic pattern in EoE patients, brought about largely by the absence of HIF-1α-mediated glycolysis, is linked with the deficit in esophageal epithelial differentiation.