FP18 Food allergen exposure drives inflammatory and differentiation responses in human keratinocytes, modulated by genetic risk for atopic disease

Introduction and aims

Food allergy occurs in 6–8% of children under 3 years of age and is often associated with atopic dermatitis (AD), but the mechanistic relationship remains controversial. There are shared genetic risks for AD and food allergy including filaggrin (FLG) loss-of-function and intergenic variants in a regulatory region for EMSY. Understanding the interactions between genetic risk and allergen exposure may lead to improvements in therapy development.

Methods

Transcriptomic changes in human primary keratinocytes with small interfering RNA-mediated FLG-knockdown (kd) (modelling increased risk of AD and allergy) or EMSY-kd (modelling decreased risk) were analysed by RNA sequencing following in vitro exposure to the following clinical-grade standardized food allergens: wheat, hen’s egg, soya, cow’s milk and peanut.

Results

Keratinocytes showed marked transcriptomic responses to food allergens, involving up to 10 273 differentially expressed genes. Themes shared among all food allergen-keratinocyte responses were proinflammatory signatures and induction of keratinization. Of note, wheat exposure increased interleukin (IL)33 mRNA expression [log2 fold change (FC) = 1.3]; soy increased CCL5 (log2 FC = 1.0) while milk allergen increased components of the interleukin (IL)-17 signalling pathways (CXCL8 log2 FC = 2.0 and CCL20 log2 FC = 1.5) and tumour necrosis factor signalling (TNFAIP3 log2 FC = 1.1); all Padj < 0.05.

As expected, FLG-kd increased innate immune signalling while EMSY-kd stimulated keratinocyte differentiation. Formal interaction analysis showed no statistically significant gene–allergen interaction, but responses were enhanced by the combination of wheat and FLG-kd (reduced TP53 signalling), soy/FLG-kd (increased inflammatory response) and peanut/FLG-kd (increased granulocyte chemotaxis). In contrast, the combination of EMSY-kd with food allergen exposure further suppressed innate immunity and apoptosis.

Conclusions

These observations illustrate molecular mechanisms by which epidermal cell signalling and genetic risk may contribute to food allergy, highlighting possibilities for future targeted intervention.