The dual allergen exposure hypothesis proposes that exposure to food antigens through the skin at a young age is more likely to lead to allergy whereas early oral consumption is more likely to lead to tolerance. New research suggests treatments centred on the skin can also play a leading role in food allergy prevention.
Food allergen sensitisation has been shown to occur in infants through skin exposure to allergenic substances, such as household peanut dust or creams containing peanut oil. Emerging evidence shows that the skin’s condition significantly influences allergen exposure outcomes, where healthy skin promotes natural tolerance, while inflamed or damaged skin is more likely to lead to sensitisation. However, only one-third of children with atopic dermatitis develop food allergies, while a significant number of children who develop food allergies do not have atopic dermatitis, suggesting the mechanism for allergen sensitisation is dependent on multiple factors.
Epicutaneous Immunotherapy (EPIT) is a new method of desensitisation therapy involving repeated application of allergens to the skin using an occlusive patch. Preclinical research has shown that applying allergens to intact, uninflamed areas of skin can reduce the immune response typically associated with allergies and induce regulatory T cells that help maintain tolerance. In studies involving children aged 1 to 11 years with peanut allergies, EPIT using an occlusive patch on areas of intact skin resulted in significant desensitisation.
Notably, the treatment was effective and safe for children both with and without atopic dermatitis, with no major differences in efficacy or safety between the two groups.
These studies begin to answer the riddle of how allergens that are applied to the skin can lead to both sensitisation and desensitisation. Further studies will help to harness the power of the skin as a complex immunologic organ to treat allergic, autoimmune, and autoinflammatory disorders.
References:
Sampson HA. The riddle of response to cutaneous allergen exposure in patients with atopic dermatitis. Ann Allergy Asthma Immunol. 2024 May DOI: 10.1016/j.anai.2024.05.005.
Marques-Mejias et al. Skin as the target for allergy prevention and treatment. Allergy Asthma Immunol. 2024 Jan 20 DOI: 10.1016/j.anai.2023.12.030.
