IL-4/IL-13-Driven Dysregulation of Epidermal Lipid Metabolism in Atopic Dermatitis: An Immunometabolic Link Between Type 2 Inflammation and Barrier Dysfunction.

Atopic dermatitis (AD) is a chronic immune-mediated inflammatory skin disease characterized by a complex and dynamic interplay between immune dysregulation and epidermal barrier dysfunction. Emerging evidence supports an integrated pathogenic model in which immune activation and barrier impairment form a bidirectional and self-reinforcing axis rather than representing separate processes. This review synthesizes current knowledge on the role of IL-4/IL-13-dependent signaling in regulating keratinocyte lipid metabolism and its impact on epidermal barrier integrity. IL-4/IL-13 signaling via the JAK-STAT pathway, particularly STAT6, contributes to keratinocyte dysfunction, resulting in impaired differentiation and coordinated alterations in lipid metabolism, including fatty acid elongation and ceramide synthesis. These cytokine-driven processes disrupt the organization of the stratum corneum lipid matrix, resulting in increased transepidermal water loss, enhanced skin permeability, and susceptibility to microbial colonization, thereby promoting chronic inflammation. Collectively, these findings support the concept that IL-4/IL-13-mediated dysregulation of keratinocyte lipid metabolism may represent an important immunometabolic mechanism linking type 2 inflammation with secondary barrier dysfunction in atopic dermatitis, thereby contributing to disease persistence. Targeting both immune pathways and epidermal lipid homeostasis may represent an effective strategy to restore barrier function and improve clinical outcomes.