Memory Cells in Atopic Dermatitis: Paving the Way to Disease Modification

Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disease in which persistence of immunological memory underlies disease recurrence and progression toward atopic comorbidities. Evidence indicates that pathogenic tissue-resident memory T cells (TRM), including Th2- and Th22-skewed subsets, among others, persist in both lesional and clinically resolved skin and rapidly re-initiate inflammation through production of IL-4, IL-13, IL-22 and IL-31, promoting barrier dysfunction and pruritus. In parallel, circulating CLA⁺ memory T cells retain skin-homing capacity and contribute to flare reactivation, while IgG1⁺CD23 IL-4Rα⁺ type-2 memory B cells (MBC2) constitute a reservoir for high-affinity IgE production, linking cutaneous inflammation with allergic comorbidities. These adaptive memory compartments are sustained by epithelial alarmins, dendritic cell-derived chemokines such as CCL17, CCL22 and CCL18, and the OX40/OX40L costimulatory pathway, which promotes differentiation, survival and tissue retention of memory T cells. Clinical and transcriptomic studies show how, although IL-4/IL-13 blockade reduces circulating type-2 responses, Th2A cells, Tc2 cells and activated dendritic cells can persist in clinically resolved skin, providing a mechanistic basis for relapse after treatment withdrawal. Together, these findings support the relevance of targeting memory-imprinting pathways as a promising mechanism to achieve durable disease modification in AD.