Minimally invasive skin tape strip RNA sequencing identifies novel characteristics of the type 2-high atopic dermatitis disease endotype

Background: Expression profiling of skin biopsy specimens has established molecular features of the skin in patients with atopic dermatitis (AD). The invasiveness of biopsies has prevented their use in defining individual-level AD pathobiological mechanisms (endotypes) in large research studies. Objective: We sought to determine whether minimally invasive skin tape strip transcriptome analysis identifies gene expression dysregulation in AD and molecular disease endotypes. Methods: We sampled nonlesional and lesional skin tape strips and biopsy specimens from white adult patients with AD (18 male and 12 female patients; age [mean SE], 36.3 +/- 2.2 years) and healthy control subjects (9 male and 16 female subjects; age [mean +/- SE], 34.8 +/- 2.2 years). AmpliSeq whole-transcriptome sequencing was performed on extracted RNA. Differential expression, clustering/pathway analyses, immunostaining of skin biopsy specimens, and clinical trait correlations were performed. Results: Skin tape expression profiles were distinct from skin biopsy profiles and better sampled epidermal differentiation complex genes. Skin tape expression of 29 immune and epidermis-related genes (false discovery rate < 5%) separated patients with AD from healthy subjects. Agnostic gene set analyses and clustering revealed 50% of patients with AD exhibited a type 2 inflammatory signature (type 2-high endotype) characterized by differential expression of 656 genes, including overexpression of IL13, IL4R, CCL22, CCR4 (log(2) fold change = 5.5, 2.0, 4.0, and 4.1, respectively) and at a pathway level by T(H)2/dendritic cell activation. Both expression and immunostaining of skin biopsy specimens indicated this type 2-high group was enriched for inflammatory, type 2-skewed dendritic cells expressing FceRI. The type 2-high endotype group exhibited more severe disease by using both the Eczema Area and Severity Index score and body surface area covered by lesions. Conclusion: Minimally invasive expression profiling of nonlesional skin reveals stratification in AD molecular pathology by type 2 inflammation that correlates with disease severity.