Improvement of sublingual immunotherapy efficacy with a mucoadhesive allergen formulation

Background: Sublingual immunotherapy is a noninvasive and efficacious treatment of type I respiratory allergies. A murine model of sublingual immunotherapy is needed to understand better the immune mechanisms involved in successful immunotherapy and to assess second-generation candidate vaccines. Objective: Herein, we developed a therapeutic murine model of sublingual immunotherapy in which we document the value of mucoadhesive formulations to enhance treatment efficacy. Methods: BALB/c mice were sublingually treated with soluble or formulated ovalbumin before or after sensitization with ovalbumin. Airways hyperresponsiveness and lung inflammation were assessed by whole-body plethysmography and lung histology, respectively. Humoral and cellular immune responses were monitored by ELISA and ELISPOT techniques. Results: Prophylactic sublingual administration of ovalbumin completely prevents airways hyperresponsiveness as well as IL-5 secretion and IgE induction. Therapeutic administration of ovalbumin as a solution via either the sublingual or oral route has a limited efficacy. In contrast, sublingual application of ovalbumin formulated with maltodextrin to enhance mucosal adhesion results in a major reduction of established airways hyperresponsiveness, lung inflammation, and IL-5 production in splenocytes. This mucoadhesive formulation significantly enhances ovalbumin-specific T-cell proliferation in cervical but not mesenteric lymph nodes, and IgA production in the lungs. Conclusion: A mucoadhesive maltodextrin formulation of ovalbumin enhances priming of the local mucosal immune system and tolerance induction via the sublingual route. Clinical implications: Mucoadhesive formulations offer the opportunity to improve dramatically sublingual immunotherapy in human beings, most particularly by simplifying immunization schemes.