Clonally expanded, GPR15-expressing pathogenic effector Th2 cells are associated with eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is an allergic disorder characterized by the recruitment of eosinophils to the esophagus, resulting in chronic inflammation. We sought to understand the cellular populations present in the esophageal biopsies of patients with EoE and to determine how these populations are altered between active disease and remission. To this end, we analyzed cells from the esophageal biopsies, duodenal biopsies, and peripheral blood of EoE patients in active disease or remission using single-cell RNA and TCR sequencing. We identified gene modules regulated by transcription factors from the NF-κB family that characterize activated eosinophils in patients with active disease. Pathogenic effector Th2 (peTh2) cells present in the esophageal biopsies of patients with active disease expressed unique gene signatures associated with the synthesis of eicosanoids that are predicted to directly promote activation of tissue-resident eosinophils. The tissue-resident peTh2 population also exhibited clonal expansion, suggesting antigen-specific activation. Peripheral CRTH2+CD161- and CRTH2+CD161+ memory CD4+ T cells were enriched for either a conventional Th2 phenotype or a peTh2 phenotype, respectively. These cells also exhibited significant clonal expansion and convergence of TCR sequences, indicating that these cells are expanded in response to a defined set of antigens. The esophagus-homing receptor GPR15 was upregulated by peripheral peTh2 clonotypes that were also detected in the esophagus. Lastly, peTh2 cells and GPR15+ cells were enriched among milk-reactive CD4+ T cells in patients with milk-triggered disease, suggesting that peTh2 cells in EoE are an expanded, food antigen-specific population with enhanced esophagus homing potential. Analysis of cells from esophageal biopsy, duodenal biopsy, and peripheral blood from patients with eosinophilic esophagitis. >>> Submitter declares that raw data cannot be published due to patient privacy concerns. <<<