Novel Nanoparticle Respiratory Tract Mucosal Vaccine

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Summary Bacterial and viral respiratory pathogens interact closely with mucosal surfaces. Specialized innate and adaptive mucosal immune systems protect these surfaces and are the first line of defense for the body. One of the more important reasons for the development of mucosal vaccines is the increasing evidence that stimulating and preparing local mucosal immune responses is important for protection against infectious against diseases, such as tuberculosis. Although the entire immune response repertoire needed for protection against Mycobacterium tuberculosis (Mtb) infection is not known, recent data in animal models suggest that vaccine-induced CD4+ cells of the T helper 17 (Th17) cell subtype, which naturally traffic to the airways, can accelerate the recruitment of protective Th1 cells and production of IFN, IL-17 and other cytokines. Cytotoxic CD8+ and CD4+ T cells also are important and can be assessed via levels of antigen-specific induction of perforin, granzyme B, and granulysin. In addition, IgA and IgG mucosal antibodies have been shown to interfere with the progression towards disease with other respiratory pathogens and may act similarly against Mtb. The respiratory epithelial cell is a primary target for mucosal vaccines. A major portion of the mucosa is comprised of cells that can provide a barrier function and serve as sensors to detect dangerous microbial components through pattern-recognition receptors and transmit signals to underlying mucosal cells to trigger innate and promote adaptive immune responses. Studies involving several Mtb secreted proteins including HBHA, Rv3351c and ESAT6 have identified links between the initial interaction of the inhaled pathogen with alveolar epithelial cells and the subsequent dissemination of the microbes from the lung. These Mtb proteins also have been shown to generate important immune responses in mice given subcutaneous or intranasal doses. Nanoparticles (NPs) are attractive mucosal vaccine/immunotherapy delivery vehicles due to the enhanced uptake by antigen-presenting cells, the preferential draining of NPs to lymphatics rather than to the bloodstream, and depending on size and composition, the ability of NPs to diffuse through mucus and cross mucosal barriers. Delivery of NP-based vaccines to the respiratory tract may be a means of enhancing innate immune responses and will be the emphasis of this study. By combining all three of these epithelial cell-targeting Mtb proteins on a NP vehicle combined with VacSIM® immune- stimulating matrix plus adjuvant, and deploying as a mucosal booster vaccine to the subcutaneous BCG prime, we expect protective cellular and humoral responses in animal lungs and significantly-elevated protection from Mtb infection compared to that conferred by BCG vaccination alone. In Aims 1 and 2, we will evaluate the efficacy and immune responses for multiple vaccine preparations and identify the two most protective which will be assessed in Aim 3 for safety, stability, and then protective efficacy will be confirmed in guinea pigs. Our hypothesis is that by stimulating humoral and cellular immune responses with our Mtb multi-antigen mucosal nanoparticle matrix vaccine, subsequent Mtb aerosol exposure will result in reduced bacterial replication in the lungs and augment systemic immune responses generated by the BCG-priming vaccine to more-effectively clear residual bacteria and decrease or prevent dissemination. We are confident this approach will be successful against Mtb in two different animal models, and thus, lay the groundwork for subsequent non-human primate trials.