Antigen-Specific mRNA–LNP Therapy with mTOR Inhibition Promotes Treg Cells and Limits Allergy

Background Immune tolerance in allergic diseases is associated with attenuation of T helper 2 (Th2) responses by shifting of antigen-specific immunity toward T helper 1 (Th1) and regulatory T cell pathways, but current strategies incompletely induce durable regulatory immunity. Objective To determine whether combining an allergen-encoded messenger RNA-lipid nanoparticle vaccine with inhibition of the mechanistic target of rapamycin (mTOR) enhances regulatory T-cell responses. Methods Mice were immunized with an allergen-encoded mRNA-lipid nanoparticle (mRNA-LNP) vaccine alone or in combination with an mTOR inhibitor, followed by induction of a preclinical model of allergic asthma. Antigen-specific T-cell responses, eosinophil activation, airway hyperresponsiveness, mucus production, and markers of cytotoxicity were assessed. Results Immunization with allergen-encoded mRNA-LNP elicited Th1-associated and cytotoxic CD8 + T responses that counterbalanced Th2 immunity. Co-administration with an mTOR inhibitor shifted this profile by promoting generation of functional regulatory T cells and attenuating IFNγ production and CD8 + T cell responses. This combinatorial strategy preserved the anti-allergic effects of mRNA-LNP immunization, reduced eosinophil activation markers, and limited vaccine-associated cytotoxicity. Conclusion The ability of an mTOR inhibitor to profoundly modify mRNA-LNP therapy by inducing regulatory T cells presents a potential strategy to enhance regulatory immunity in the treatment of allergy and other inflammatory diseases.