Topical corticosteroids normalize both skin and systemic inflammatory markers in infant atopic dermatitis

BACKGROUND: Atopic dermatitis (AD) is the most common inflammatory skin disease. It is highly heterogeneous in clinical presentation, treatment response, disease trajectory and associated atopic comorbidities. Immune biomarkers are dysregulated in skin and peripheral blood. AIMS: We used noninvasive skin and peripheral biomarkers to observe the effects of real‐world topical corticosteroid (TCS) treatment in infants with AD, by measuring skin and blood biomarkers before and after therapy. METHODS: Seventy‐four treatment‐naïve infants with AD underwent 6 weeks of TCS treatment. Stratum corneum (SC) and plasma blood biomarkers as well as SC natural moisturizing factor (NMF) were measured before and after TCS therapy. Immune markers included innate, T helper (Th)1 and Th2 immunity, angiogenesis, and vascular factors. AD severity was assessed by the Scoring Atopic Dermatitis index, and skin barrier function by transepidermal water loss (TEWL). Twenty healthy infants were recruited as controls. RESULTS: TCS therapy predictably led to improvement in disease severity. Levels of immune markers in the skin and in the peripheral blood showed significant change from baseline, though most did not reach healthy control levels. The most prominent change from baseline in the SC was in markers of innate immune activation, interleukin (IL)‐18, IL‐8 and IL‐1α, and the Th2 chemokines C‐C motif chemokine (CCL)17 and CCL22. In blood, the largest changes were in Th2‐skewed biomarkers: CCL17, IL‐13, CCL22, IL‐5, and CCL26. TEWL decreased after therapy; no significant changes from baseline were found for NMF. CONCLUSIONS: The profound impact of topical therapy on systemic biomarkers suggests that the skin compartment generates a major component of dysregulated systemic cytokines in infant AD. There may be long‐term beneficial effects of correcting systemic immune dysregulation through topical therapy.