Blockade of IL-13 signaling improves skin barrier function and biology in patients with moderate to severe atopic dermatitis

Abstract Background Interleukin (IL)-13 is a key driver of inflammation and barrier dysfunction in atopic dermatitis (AD). While there is robust evidence that tralokinumab – a monoclonal antibody that neutralizes IL-13 – reduces inflammation and clinical disease activity, less is known about its effects on barrier function. Objectives To characterize the effects of tralokinumab treatment on skin barrier function. Methods Transepidermal water loss (TEWL), stratum corneum hydration (SCH), natural moisturizing factor content, histopathological characteristics, biomarker expression and microbiome composition were evaluated in lesional, nonlesional and sodium lauryl sulfate-irritated skin of 16 patients with AD over the course of 16 weeks of tralokinumab treatment. Results All clinical severity scores decreased significantly over time. At week 16, mean TEWL in target lesions decreased by 33% (P = 0.01) and SCH increased by 58% (P = 0.004), along with a histological reduction in spongiosis (P = 0.003), keratin 16 expression and epidermal thickness (P = 0.001). In parallel, there was a significant decrease in several barrier dysfunction-associated and proinflammatory proteins such as fibronectin (P = 0.006), CCL17/TARC (P = 0.03) and IL-8 (P = 0.01), with significant changes seen as early as week 8. Total bacterial load and Staphylococcus aureus abundance were significantly reduced from week 2. Conclusions Tralokinumab treatment improved skin physiology, epidermal pathology and dysbiosis, further highlighting the pleiotropic role of IL-13 in AD pathogenesis.