T helper 22 cells from Han Chinese patients with atopic dermatitis exhibit high expression of inducible T‐cell costimulator

Our findings demonstrate that ICOS/ICOSL expression and effects are linked to Th22 skewing and the pathogenesis of Han Chinese AD, which suggests ICOSL and ICOS as well as Th22 cells and IL-22 as new and promising therapeutic targets. What's already known about this topic? In Asian patients, atopic dermatitis (AD) is characterized by excess T helper (Th) 22 activation. Inducible T-cell costimulator (ICOS) is crucial for T-cell activation and differentiation. What does this study add? This study demonstrates that circulating Th22 cells, serum levels of interleukin (IL)-22 and IL-22⁺ cells are all markedly increased in lesional skin in Han Chinese patients with AD. In Han Chinese patients with AD, ICOS and ICOS ligand (ICOSL) drive Th22 skewing and increase filaggrin downregulation, and ICOS⁺ Th22 cells and ICOSL⁺ B cells are linked to disease activity. What is the translational message? ICOS⁺ Th22 cells and ICOSL⁺ B cells are potential clinical biomarkers of disease activity in Han Chinese patients with AD. ICOS- and ICOSL-targeted treatment approaches may benefit Han Chinese patients with AD.