Skin sensitisation to gluten in the absence and presence of atopic dermatitis drives changes in skin and systemic T cell phenotype composition in a rat model of food allergy

Atopic dermatitis is associated with higher risk for developing immune-related comorbidities, including other atopic diseases like food allergy as well as certain infections, autoimmune diseases, and cancers. It remains largely unknown whether this increased risk of comorbidities is attributable to underlying AD-induced changes in non-skin immune composition and function beyond the exacerbation of allergic immune responses. Here Brown Norway rats were sensitised to hydrolysed gluten though the skin in the absence or presence of AD-like skin inflammation induced by topical application of MC903. T cell phenotype composition was analysed in skin, blood, and gut tissues by flow cytometry. M1/M2 differentiation and cytokine production by intraperitoneal-derived macrophages stimulated with bacteria, inflammatory cytokines, or food allergens were analysed using flow cytometry and ELISA. Gut microbiota composition was analysed by partial 16S rRNA gene sequencing. Sensitisation in both the absence and presence of induced AD-like skin inflammation was found to predominantly affect T cell phenotype composition in skin and blood immune compartments. This systemic effect of AD had a minor effect on M1/M2 differentiation but did not affect cytokine production by intraperitoneal-derived macrophages. These findings highlight some systemic effects of skin sensitisation and AD that potentially could affect non-skin immune responses.