Purpose of review: mRNA vaccines have recently been re-discovered as an attractive alternative to the more prominent DNA vaccines, as they harbor many advantages with respect to safety and regulatory issues. Whereas most mRNA vaccines are focused on tumor therapy, this type of vaccine has now also been successfully employed for prophylactic immunization against type I allergy in a mouse model. This concept differs from conventional immunotherapy in that it relies on immune deviation toward a TH1 phenotype, rather than induction of regulatory T cells or tolerance.
Recent findings: Conventional as well as self-replicating mRNA vaccines have demonstrated their potential to prevent the induction of an allergic phenotype in terms of allergen-specific IgE, allergy-associated cytokine profiles, eosinophilic lung infiltration, and airway hyperreactivity. Preliminary data raise the question whether TH1 immune deviation induced by mRNA vaccination resembles the natural phenotype of a certain proportion of nonatopic individuals.Reservations regarding Good Manufacturing Practices manufacture costs, shelf life stability, and lack of immunogenicity due to rapid in-vivo degradation have been overcome by novel findings.
Summary: mRNA vaccines open the field for a safety-optimized prophylactic vaccination against allergic diseases. Future studies concerning long-term effects and vaccine-induced versus natural immune responses will be needed to transfer this knowledge to the clinics.