The Hydrogel Based Allergen-Coated Gold Nanoparticles for Topical Administration: A Possible Epicutaneous Immunotherapy in Pollen-Sensitized Mice?

Background: The rapid uptake of antigens by antigen-presenting cells (APCs) and their migration to draining lymph nodes in the initial hours after antigen administration in epicutaneous allergen specific immunotherapy (EPIT) prompted us to investigate whether the topical administration of allergens without patch application could alleviate allergy in pollen-sensitized mice. We evaluated the immunotherapeutic effect of topically administering hydrogel-based Gold nanoparticles (AuNPs) loaded with a total extract of Platanus orientalis pollen (Pla. ext (50 mu g)-AuNPs) on intact skin.Methods: Mice sensitized to P. orientalis pollen were divided into three groups and treated with Pla. ext (50 mu g)-AuNPs: 1) patch with Pla. ext (50 mu g)-AuNPs, 2) patch with Pla. ext (50 mu g)-AuNPs in combination with hydrogel, and 3) topical application of Pla. ext (50 mu g)-AuNPs in combination with hydrogel. The immunotherapeutic effects were evaluated by measuring serum specific and total IgE antibodies, total cell and eosinophil count in nasopharyngeal lavage fluid, cytokines in the supernatants of re-stimulated splenocytes by the total extract, and histological examination of lung and nasal mucosa.Results: Topical administration of Pla. ext (50 mu g)-AuNPs, like patch-based administration, significantly downregulated specific and total IgE and IL-4 production, promoted secretion of IFN-gamma and IL-10, markedly reduced the number of inflammatory cells, particularly eosinophils, in nasopharyngeal lavage fluid (p < .05), and inhibited inflammation and pathological damage in lung and nasal mucosa.Conclusion: Our results suggest that topical administration of AuNPs loaded with P. orientalis total pollen extract on intact skin could be a potential application for EPIT in the P. orientalis pollen -sensitized mice.