Airway mucociliary dysfunction enhances antigen-specific nasal IgA immune responses to cholera toxin-based nasal vaccine

Abstract Nasal mucosal tissues are equipped with physical barriers, mucus and cilia, on their surface. The mucus captures inhaled materials, and the cilia remove the captured materials from the epithelial layer by asymmetrical beating. Effect of nasal physical barriers on the vaccine efficacy remains to be investigated. Tubulin tyrosine ligase-like family member 1 (Ttll1) is an essential enzyme for appropriate movement of the cilia on respiratory epithelium, and its deficiency (Ttll1-KO) leads to the impaired asymmetrical beating of cilia and consequent mucus accumulation in the nasal cavity. Here, when mice were intranasally immunized with pneumococcal surface protein A (PspA) together with cholera toxin, Ttll1-KO mice showed higher levels of PspA-specific IgA in the nasal wash and increased numbers of PspA-specific IgA-producing plasma cells in the nasal passages when compared with Ttll1 hetero (He) mice. Mucus removal by N-acetylcysteine did not affect the enhanced immune responses in Ttll1-KO mice. We further found that retention time of PspA in the nasal cavity in Ttll1-KO mice was longer than that in Ttll1-He mice. Consistently, uptake of PspA by dendritic cells was higher in the nasopharynx-associated lymphoid tissue (NALT) of Ttll1-KO mice than that of Ttll1-He mice. These results indicate that the ciliary function of removing vaccine antigen from the NALT epithelial layer is a critical determinant of the efficacy of nasal vaccine.