BACKGROUND

Children with atopic dermatitis (AD) are often sensitized to food and aeroallergens, but sensitization patterns have not been analysed with biologic measures of disease pathogenicity.

OBJECTIVE

We sought to define allergen sensitization grouping(s) using unbiased machine learning and determine their associations with skin filaggrin (FLG) and transepidermal water loss (TEWL) (assesses skin barrier integrity), S100A8 and S100A9 expression (assesses skin inflammation) and AD severity.

METHODS

We studied 400 children with AD in the Mechanisms of Progression from Atopic Dermatitis to Asthma in Children (MPAACH) cohort to identify groupings of food and aeroallergen sensitizations. MPAACH is a paediatric AD cohort, aged 1-2, recruited through hospital/community settings between 2016 and 2018. We analysed these groupings' associations with AD biomarkers: skin FLG, S100A8 and S100A9 expression, total IgE, TEWL and AD severity.

RESULTS

An unbiased machine learning approach revealed five allergen clusters. The most common cluster (N = 131), SPT had sensitization to peanut, egg and/or pets. Three low prevalence clusters, which included children with allergen sensitization other than peanut, egg or pets, were combined into SPT . SPT included children with no sensitization(s). SPT children had higher median non-lesional TEWL (16.9 g/m /h) and IgE (90 kU/L) compared with SPT (8.8 g/m /h and 24 kU/L; p = .01 and p < .001) and SPT (9 g/m /h and 26 kU/L; p = .003 and p < .001). SPT children had lower median lesional (0.70) and non-lesional (1.09) FLG expression compared with SPT (lesional: 0.9; p = .047, non-lesional: 1.78; p = .01) and SPT (lesional: 1.47; p < .001, non-lesional: 2.21; p < .001). There were no differences among groupings in S100A8 or S100A9 expression.

CONCLUSIONS AND CLINICAL RELEVANCE

In this largely clinic-based cohort of young children with AD, allergic sensitization to peanut, egg, cat or dog was associated with more severe disease and skin barrier function but not markers of cutaneous inflammation. These data need replicating in a population-based cohort but may have important implications for understanding the interaction between AD and allergic sensitization.