Sublingual Immunotherapy Efficacy of Dermatophagoides farinae Vaccine in a Murine Asthma Model

Background: Allergen-specific sublingual immunotherapy is a potential treatment for allergic diseases. Its effective dose and underlying mechanism are still to be explored. Here, we investigated the efficacy and mechanism of sublingually administered Dermatophagoides farinae (Der f) vaccine in a murine asthma model. Methods: BALB/c mice were sensitized intraperitoneally with Der f extract absorbed to alum, followed by sublingual treatment with Der f vaccine for 6 weeks. The mice were subsequently challenged intranasally with Der f extract for 1 week. We analyzed their clinical symptoms, antibody levels, cytokine levels, T-cell proliferation and the regulatory T-cell numbers. Results: Mice treated with high-dose Der f sublingual vaccine prior to challenge displayed alleviated symptoms such as airway hyperreactivity, lung inflammation and mucus production, as well as less eosinophilic cells in bronchoalveolar lavage fluid. Interestingly, reduced responses of Der-f-specific IgE and increased responses of Der-f-specific IgA and IgG1 were aroused in the high-dose Der f sublingual vaccine group. We also observed that interleukin-4 was reduced and interferon-gamma and interleukin-10 were increased among splenocytes and in bronchoalveolar lavage fluid, which inhibited Der-f-specific T-cell proliferation of the spleen and increased CD4+CD25+Foxp3+ regulatory T cells in the spleen. However, mice treated with low-dose Der f sublingual vaccine developed allergic asthma. Conclusion: Our results illustrate that high-dose Der f sublingual vaccine may play a role in immunologic protection in murine allergic asthma, possibly by inducing regulatory T cells and Th1 reaction. Copyright (C) 2009 S. Karger AG, Basel