Epicutaneous Immunotherapy on Intact Skin Using a New Delivery System in a Murine Model of Allergy

Background: Allergen-specific immunotherapy, subcutaneous immunotherapy (SCIT) or oral, has been used for almost a century to redirect inappropriate immune responses in atopic patients. A new mode of administration through the intact skin [epicutaneous immunotherapy (EPIT)], using an original epicutaneous delivery system, may represent an alternative to these classical methods.

Objective: Proof of concept of efficacy of EPIT on intact skin in mice sensitized to aeroallergens or food allergens.

Methods: Mice were sensitized to pollen (n=18), house dust mite (HDM, n=24), ovalbumin (OVA, n=18) or peanut (n=18), and allocated to four groups: EPIT, SCIT, not treated (NT) and control. Specific Ig (sIg)E, sIgG1 and sIgG2a were monitored. After 8 weeks of treatment, plethysmography was performed after aerosol provocation with appropriate allergens.

Results: At the highest doses of methacholine, pause enhancement (Penh) values were significantly decreased in the EPIT group vs. the sensitized NT groups (7.5 vs. 12.3 - pollen, 7.6 vs. 8.9 - HDM, 11.5 vs. 14.5 - OVA, 7.6 vs. 12.8 - peanut, respectively) (P<0.05). With all the allergens tested, Penh values were similar in SCIT, EPIT and control. IgG2a for pollen, HDM, OVA and peanuts were significantly increased in the EPIT group vs. NT: 0.97 vs. 0.42 microg/mL, 2.5 vs. 0.46 microg/mL, 0.39 vs. 0.05 microg/mL and 15.0 vs. 5.5 microg/mL, respectively (P<0.05). There were no significant differences between EPIT and SCIT groups. The IgE/IgG2a ratio decreased significantly in the EPIT group for the four allergens from 70 to 58 (pollen), 175 to 26 (HDM), 5433 to 120 (OVA) and 49 to 6 (peanut), respectively (P<0.05).

Conclusion: In mice sensitized to the four allergens tested, EPIT was as efficacious as SCIT, considered as the reference immunotherapy. These first results have to be confirmed by clinical studies.