Abstract
Eosinophilic esophagitis (EoE) is a leading cause of chronic esophageal dysfunction driven by immune-mediated inflammation. Peak eosinophil count (PEC) in esophageal biopsies is routinely used to assess disease activity, and its associated molecular mechanisms have been well studied. However, PEC only partially captures overall disease severity, which is comprehensively captured by the Index of Severity for Eosinophilic Esophagitis (I-SEE). In contrast to PEC, the molecular and cellular programs associated with the I-SEE-defined disease severity, particularly in children, remain poorly understood. We integrated bulk transcriptomic profiling of pediatric esophageal biopsies with clinical severity metrics and a matched single-cell transcriptomic reference. Increasing severity was associated with a shift from type 2 inflammatory activation toward epithelial stress, cytoskeletal and junctional disruption, metabolic dysfunction, and extracellular matrix remodeling. Single-cell-informed analyses identified that proliferating and transitional epithelial cell states were strongly associated with higher I-SEE scores and exhibited impaired differentiation, heightened metabolic and oxidative stress responses, and structural remodeling programs not captured by bulk transcriptomic analyses alone. These findings reposition epithelial remodeling, rather than eosinophil burden alone, as a central molecular correlate of disease severity in pediatric EoE and provide a framework for improved disease stratification and therapeutic intervention.