IL25 (interleukin 25), also known as IL-17E, is a barrier surface cytokine primarily produced by epithelial cells, tuft cells, and various immune cells that serves as a key regulator of type 2 immunity 1. The protein functions as a chemosensory sentinel that integrates luminal conditions and triggers appropriate immune responses through its receptor complex composed of IL17RA and IL17RB 2. IL25 strongly induces expression of type 2-associated cytokines including IL-4, IL-5, and IL-13, while inhibiting Th17 cell differentiation 1. In barrier tissues, IL25 represents a prototypical epithelial response to proteolytic allergens or helminths, programming dendritic cells to mount Th2-mediated immunity and boosting ILC2, basophil, and mast cell function 3. The cytokine plays dual roles in disease: it contributes to host defense against helminth infections but also drives chr14 allergic diseases including asthma, atopic dermatitis, and chr14 rhinosinusitis through type 2 inflammatory responses 4. Clinically, elevated IL25 expression is associated with poor prognosis in colorectal cancer by creating a cancer-permissive microenvironment through ILC2 activation and myeloid-derived suppressor cell recruitment 5. IL25 also serves as a promising biomarker for monitoring disease activity in eosinophilic granulomatosis with polyangiitis 6.