Pathophysiology
Clinical meaning
Eosinophilic esophagitis represents a paradigm of chronic Th2-polarized mucosal inflammation driven by a complex interplay between genetic susceptibility, epithelial barrier dysfunction, and antigen-specific immune activation. Genome-wide association studies (GWAS) have identified the EoE susceptibility locus on chromosome 5q22 encompassing the TSLP (thymic stromal lymphopoietin) gene, and the 2p23 locus harboring the CAPN14 (calpain-14) gene. TSLP, an epithelial-derived alarmin cytokine released in response to allergen exposure, activates dendritic cells to promote Th2 polarization. Calpain-14, an intracellular protease induced by IL-13 in esophageal epithelial cells, cleaves desmoglein-1 and disrupts epithelial barrier integrity, creating a positive feedback loop of barrier dysfunction → allergen penetration → Th2 amplification. The molecular cascade begins when food or aeroallergens penetrate the disrupted epithelial barrier and are captured by CD11c+ dendritic cells in the esophageal lamina propria. These dendritic cells migrate to regional lymph nodes and present antigen to naïve CD4+ T cells in the context of TSLP-primed co-stimulation, driving Th2 differentiation. The resulting Th2 effector cells home to the esophageal mucosa via integrin α4β7 and CCR3-mediated chemotaxis. IL-4 from Th2 cells drives B cell class switching to...