Specific immunotherapy (SIT) is the most widely used treatment for allergic diseases that directly targets the T helper 2 (Th2) bias underlying allergy. However, the most widespread clinical applications of SIT require a long period of dose escalation with soluble antigen (Ag) and carry a significant risk of adverse reactions, particularly in highly sensitized patients who stand to benefit most from a curative treatment. Thus, the development of safer, more efficient methods to induce Ag-specific immune tolerance is critical to advancing allergy treatment. We hypothesized that antigen-associated nanoparticles (Ag-NPs), which we have used to prevent and treat Th1/Th17-mediated autoimmune disease, would also be effective for the induction of tolerance in a murine model of Th2-mediated ovalbumin/alum-induced allergic airway inflammation. We demonstrate here that antigen-conjugated polystyrene (Ag-PS) NPs, although effective for the prophylactic induction of tolerance, induce anaphylaxis in presensitized mice. Antigen-conjugated NPs made of biodegradable poly(lactide-co-glycolide) (Ag-PLG) are similarly effective prophylactically, are well tolerated by sensitized animals, but only partially inhibit Th2 responses when administered therapeutically. PLG NPs containing encapsulated antigen [PLG(Ag)], however, were well tolerated and effectively inhibited Th2 responses and airway inflammation both prophylactically and therapeutically. Thus, we illustrate progression toward PLG(Ag) as a biodegradable Ag carrier platform for the safe and effective inhibition of allergic airway inflammation without the need for nonspecific immunosuppression in animals with established Th2 sensitization.
Keywords: Th2 cells; allergy; immunotherapy; nanoparticles; tolerance.