Children with both atopic dermatitis and food allergy have stratum corneum abnormalities that distinguish them from other atopic dermatitis endotypes and children without atopic disease, according to a study published in Science Translational Medicine.
Investigators sought to determine whether children with atopic dermatitis and food allergy have specific skin features that distinguish them from children with atopic dermatitis without food allergy and children without a history of atopic disease or food allergy (control group). A total of62 children were divided into 3 diagnostic groups: children with atopic dermatitis with food allergy (n=21), children with atopic dermatitis without food allergy (n=19), and children without atopic disease or food allergy (n=22). All groups were balanced for age, sex, and race, and the 2 atopic dermatitis groups had similar disease severity. Skin tape stripping was used to sample skin and provide protein and lipid profiles, as well as to analyze transepidermal water loss and stratum corneum composition.
Children in the atopic dermatitis with food allergy group reacted immediately to peanut ingestion and had allergic sensitizations to peanut (skin prick wheal size: ≥8 mm) and other foods, whereas the other 2 groups tolerated peanut ingestion and had negative skin prick reactions. The researchers observed a significant increase in peanut-specific immunoglobulin E (IgE) in atopic dermatitis children with food allergy vs without food allergy (P <.001). Compared with atopic dermatitis without food allergy and nonatopic skin, increased transepidermal water loss was found in nonlesional skin of children with atopic dermatitis with food allergy, suggesting substantially reduced skin barrier function in this population.
Of the 3 diagnostic groups, the atopic dermatitis with food allergy group had the lowest amount of filaggrin breakdown products in nonlesional skin layers, as well as a lower proportion of ω-hydroxy fatty acid sphingosine ceramide content. In transcriptome analysis, abnormal expression of keratins and immune activation involving type 2 cytokines in the stratum corneum were related to the reduction in filaggrin abundance, in which the filaggrin protein plays an important role in keratinocyte differentiation.
Ttranscriptome analysis was successful in only a fraction of participants because of the limited amount of RNA that can be extracted via skin tape stripping. In the future, skin biopsies would be beneficial to confirm these findings, as well as to examine the changes that may be found in deeper layers of skin.
The investigators suggested that atopic dermatitis with food allergy is associated with abnormal skin barrier function indicated by greater transepidermal water loss, low filaggrin composition, and decreased ω-hydroxy fatty acid sphingosine ceramide content. Further research focusing on improving skin barrier function in this population is needed.
Leung DYM, Calatroni A, Zaramela LS, et al. The nonlesional skin surface distinguishes atopic dermatitis with food allergy as a unique endotype. Sci Transl Med. 2019;11(480).