Nasal mucosal epithelium and mucosal antigen-presenting cells

The nasal mucosal epithelium and mucosal antigen-presenting cells (APCs) represent a complex physiological system rather than a single molecular target, serving as the primary immunological and physical barrier of the upper respiratory tract. The epithelium is composed of ciliated cells, goblet cells, and specialized microfold (M) cells that facilitate the transport of inhaled antigens to underlying lymphoid structures, such as the nasal-associated lymphoid tissue (NALT) [1, 5]. Within this environment, mucosal APCs, including dendritic cells and macrophages, actively sample the airway lumen to initiate adaptive immune responses, characterized by the production of secretory IgA [2, 3]. This site is a critical focus for the development of intranasal vaccines, as it can provide sterilizing immunity against respiratory pathogens like influenza and SARS-CoV-2 by blocking entry at the portal of infection [4]. Furthermore, the high permeability and extensive vascularization of the nasal mucosa are exploited for the non-invasive systemic delivery of various drugs, although therapeutic efficacy can be limited by mucociliary clearance and the risk of unintended transport to the central nervous system via the olfactory pathway [6]. Sources: [1] Brandtzaeg, P. (2011) Mucosal Immunology; [2] Kiyono, H., & Azegami, T. (2015) Nature Reviews Immunology; [3] Takano, K. (2020) Japanese Journal of Clinical Immunology; [4] Lavelle, E. C., & Ward, R. W. (2022) Nature Reviews Immunology; [5] Pires, A., et al. (2009) Journal of Pharmacy & Pharmaceutical Sciences; [6] Djupesland, P. G. (2013) Drug Delivery and Translational Research.

Other names

Nasal mucosaNasal-associated lymphoid tissueNALTNasal epithelial barrierSchneiderian membrane

Vaccines interact with this site via antigen capture by M-cells and dendritic cells to induce mucosal IgA and systemic immune responses [1, 2]. Therapeutic agents like corticosteroids bind to intracellular receptors in epithelial cells to suppress inflammatory cytokines, while systemic drugs utilize the high vascularization of the respiratory epithelium for rapid absorption into the bloodstream [3, 4].