Methotrexate and ciclosporin both reduce levels of circulating interleukin (IL)-4 and IL-13 expressing CD4+ memory T cells in childhood atopic dermatitis.

Atopic dermatitis (AD) is a chronic dermatosis characterized by type-2 inflammatory responses, skin barrier anomalies and microbiome dysregulation. The variety of AD presentations necessitates a better understanding of the underlying disease mechanisms and the modulation of immune markers over a treatment course. Globally, the most used systemic therapies for moderate-to-severe AD are methotrexate (MTX) and ciclosporin (CyA). The TReatment of severe Atopic Eczema in children Trial (TREAT) was a randomized controlled trial (RCT) assessing the efficacy and safety of MTX and CyA. Peripheral blood samples from 18 TREAT participants were analysed in a longitudinal immunological study with a focus on cytokine-expressing CD4+ T cells. The analysis showed that both MTX and CyA were associated with a decreased percentage of interleukin (IL)-4 and IL-13 expressing CD4+ memory T cells, corresponding to improved disease severity. Patients receiving MTX experienced a more sustained decrease in IL-4 expressing T cells, which corresponds to the longer-term improved disease control observed in the MTX arm.