Epicutaneous exposure to food antigens, especially via eczema and barrier-disrupted sites, reportedly causes allergic sensitization. However, an optimal window of age regarding this sensitization remains poorly understood. In this murine study, we investigated whether age influences the degree of epicutaneous sensitization.
Dorsal skin of wild type BALB/c female mice (1, 3, 8 and >15 weeks old) was shaved and tape-stripped. A Finn chamber containing 20 μl of a 20 mg/ml ovalbumin (OVA) solution was placed on the skin site for 24h x 3 consecutive days/week for 3 weeks. The rectal temperature was measured after intraperitoneal OVA challenge. Serum OVA-specific IgE titers and cytokine production by OVA-stimulated splenocytes were measured by ELISA. mRNA expression levels in the dorsal skin were measured by qPCR. The number of dermal dendritic cells (dDCs) that migrated to the draining lymph nodes was determined by FITC-labeled OVA and flow cytometry.
A significant age-dependent body temperature decline was observed after OVA challenge. The serum OVA-specific IgE titer, OVA-dependent cytokine production (IL-5, IL-13) by splenocytes, and the number of migrated dDCs, mRNA expression for IL-33, but not TSLP or IL-25, in the skin was observed at 4h after tape-stripping each increased with age.
Induction of epicutaneous sensitization (anaphylaxis, serum OVA-specific IgE, OVA-dependent Th2 cytokine production by splenocytes and local IL-33 mRNA expression) following tape-stripping was more profound in older mice than younger mice. The mechanisms of how aging causes such changes should be further studied.