Tape strip transcriptomic profiling of children and adults with mild-to-moderate atopic dermatitis in a Thai population

Summary: Abstract Body: Atopic dermatitis (AD) is a heterogeneous disease, with varying clinical and molecular features based on age, severity, ethnicity, etc. While tape strips have characterized many AD endotypes, molecular profiling of mild-to-moderate AD in a Southeast Asian population has never been done. We enrolled Thai children age<12 years with mild AD (SCORAD<25, n=13), moderate AD (25≤SCORAD<50, n=12), and matched healthy controls (HC) (n=8) and included adults with mild AD (n=9), moderate AD (n=7), and HC (n=10) from Thailand. Tape strips were collected from the lesional(LS) and non-lesional(NL) skin of AD patients and HCs for RNAseq analysis. Differentially expressed genes (DEGs) were defined by fold change>1.5 and false discovery rate<0.05. Overall, the LS tape strip transcriptome was significantly more inflamed in moderate vs mild AD in adult (moderate:1348 DEGs, mild:453 DEGs) and pediatric AD (moderate:905 DEGs,mild: 53 DEGs). 7 DEGs were detected amongst all NL samples, suggesting minimal systemic inflammation in this cohort. T-cell and dendritic cell activation products (CD4/ITGAM/ITGAX) were only upregulated in adult moderate AD. Th2 (IL4R/IL13/CCL17) and Th1 (IL1B/CCR1) markers were upregulated in mild-to-moderate AD adult LS skin, but not in children. However, IL5, a Th2 cytokine and eosinophil mediator was elevated only in moderate child AD. The Th17/Th22 axis was enriched across all AD groups, though several Th17 genes (CXCL1/IL6/IL-23A/S100A9) were more elevated in moderate child AD. Barrier alterations were also seen across the entire AD cohort, with several barrier products (GJB3/FA2H/GAL/KRT79) showing greatest decreases in moderate child AD. The tape strip molecular phenotype of Thai patients with mild-to-moderate AD revealed distinct immune and barrier signatures based on age and severity level, identifying potential biomarkers for disease monitoring and therapeutic targeting. Daniel Liu¹, Panipak Temboonnark^{1, 2, 3}, Ester Del Duca¹, Yeriel Estrada¹, Jonathan Bar¹, Helen He¹, Emma Guttman-Yassky¹ 1. Dermatology, Icahn School of Medicine at Mount Sinai, New York, NY, United States. 2. Pediatrics, Queen Sirikit National Institute of Child Health, Bangkok, Thailand. 3. Medicine, Rangsit University, Bangkok, Thailand. Minoritized Populations and Health Disparities Research