Development of Mucosal Vaccines as Novel Preventive Methods against Infectious and Noncommunicable Diseases (NCDs)

The surface layer of the mucosa, which in adult humans, is estimated to have a surface area over 200 times greater than that of the skin, is constantly in contact with foreign antigens, against which non-specific defense (innate immune mechanisms) and specific defense (acquired immune mechanisms) are activated. In the mucosal areas that are the entry points for foreign antigens, the efficient production and secretion of secretory IgA (SIgA) antibodies, which are the main form of specific defense, and mucosal vaccines, which are an efficient antigen delivery system for inducing and promoting antibody production, may offer a strategic tool for preventing not only infections, but also the development of lifestyle-related diseases. We have previously undertaken research and development of an immunostimulating agent (adjuvant) for use with mucosal vaccines based on mucosal immunity, particularly nasal vaccines that are administered to the nasal cavity. More specifically, a double DNA adjuvant (dDA) system that targets dendritic cells, which are one of antigen-presenting cells, was developed, and basic research was conducted using a number of different antigens, including a comparison of the immune response to these antigens when they were introduced into the nasal cavities of young and old experimental animals (mice). Of late, we have been working toward the development of a mucosal vaccine capable of preventing infection or lifestyle-related disease that can also be used in older people. In this review article, I will introduce the advantages of mucosal vaccines as well as recent findings in our group.