Intranasal Immunotherapy with Allergen-Loaded Extracellular Vesicles from Mast Cells Alleviates Allergic Asthma Inflammation in a Murine Model.

Allergen immunotherapy (AIT) is the only treatment that can alter the course of allergic diseases by inducing immune tolerance through long-term, repeated low-dose allergen exposure. Nonetheless, AIT persistently faces challenges necessitating resolution, particularly in relation to treatment duration, the incidence of adverse reactions, and patient adherence. Extracellular vesicles (EVs) are promising drug delivery carriers for medications, vaccines, and targeted antibodies. Previously, we demonstrated that intravenous bone marrow-derived mast cell EVs (BMMC-EVs) can reduce allergic airway inflammation in asthmatic mice by interacting with free IgE. This study explores the potential of intranasally administered BMMC-EVs loaded with dermatophagoides farinae extracts to induce local immune tolerance and more effectively alleviate allergic asthma in mice. BMMC were co-cultured with the crude extract of dermatophagoides farina (DfE). BMMC-EVs-DfE were obtained and analyzed for the presence and concentration of DfE. The allergic asthma model was sensitized by intraperitoneal injection of DfE and Al(OH)₃ in BALB/c mice. Mice were immunized with PBS, BMMC-EVs-DfE, BMMC-EVs, and DfE intranasally. Then, mice were challenged with DfE after treatment. Effects of immunization were analyzed based on lung histology, bronchoalveolar lavage cell counts, lung cytokine levels, and plasma antibody levels. There were no deaths or signs of systemic toxicity noted in association with the BMMC-EVs-DfE, BMMC-EVs, and DfE immunized mice. BMMC-EVs-DfE immunization could decrease the total cells, macrophages and eosinophils number in bronchoalveolar lavage fluid (BALF), and attenuate goblet cell hyperplasia and MUC5AC expression in lung tissue. DfE specific IgE and IgG3 antibody, and histamine levels were significantly suppressed by BMMC-EVs-DfE immunization, while DfE specific IgG1 and IgG2a levels were increased. Moreover, BMMC-EVs-DfE can regulate the Th1/Th2 balance toward Th1 via increasing the IFN-γ and decreasing the IL-4 levels. We demonstrate here that BMMC-EVs-DfE could efficiently prevent allergic asthma inflammation, rebuild Th1/Th2 balance, reduce goblet hyperplasia and mucus production. BMMC-EVs-DfE as a platform for allergen delivery that effectively inhibits asthma airway inflammation.