P12 Massage-induced skin stretching facilitates the cutaneous permeation of peanut proteins

Abstract Introduction and aims Cutaneous exposure to food allergens prior to oral exposure has been associated with sensitization and the development of food allergies (Lack 2008). Similarly, the prevalence of food allergies has been linked to the frequency of massage in babies (Perkin et al. 2021). However, the mechanism by which environmental food allergens come into contact with the immune cells responsible for sensitization in the skin or how skin massage may facilitate this process is currently unknown. This study aimed to investigate whether massage-induced skin stretching facilitated the percutaneous permeation of food allergens into the skin. Methods Hydrophilic and hydrophobic proteins were extracted from raw and roasted peanuts and fluorescently labelled with Sulfo Cyn5 NHS ester. Franz diffusion cells mounted with full-thickness mice skin (Balb/C, 8–12 weeks old) were employed to assess the skin penetration of the peanut proteins with [stretch (+)] and without [stretch (−)] skin stretching. Results Peanut roasting led to significant changes in the peanut protein composition compared with raw peanuts with hydrophilic protein Ara h −1 aggregate formation and reduced hydrophobic olesion and caleosin protein levels. When applied to the tissue without stretching, a small amount of the peanut protein passed into and through the tissue regardless of peanut type or processing. However, stretching increased the peanut penetration of all the extracts applied to the skin. The raw hydrophilic and roasted hydrophobic peanut extracts showed the most extensive tissue penetration at 9.5 ± 8.4 µg cm−2 and 7.2 ± 5.9 µg cm−2, respectively. Conclusions Increasing skin tension by 4–5 fold, akin to the skin stretching experienced during baby massage, enhances percutaneous permeation of peanut proteins into the skin. Therefore, skin stretching may contribute to the process of cutaneous allergen sensitization. Further work is needed to understand the clinical relevance of hydrophilic, hydrophobic and aggregated peanut proteins entering the skin during stretching.