Tissue Microenvironments in the Nasal Epithelium of Rainbow Trout (Oncorhynchus mykiss) Define Two Distinct CD8α+ Cell Populations and Establish Regional Immunity

• Published in: The Journal of immunology (1950) Vol. 197; no. 11; pp. 4453 - 4463
• Main Authors: Sepahi, Ali, Casadei, Elisa, Tacchi, Luca, Muñoz, Pilar, LaPatra, Scott E, Salinas, Irene
• Format: Journal Article
• Language: English
• Published: United States 01-12-2016
• Subjects: Animals; CD8 Antigens - immunology; CD8-Positive T-Lymphocytes - immunology; Cellular Microenvironment - immunology; Chemokine CCL19 - immunology; Fish Proteins - immunology; Immunity, Cellular; Immunity, Mucosal; Intercellular Adhesion Molecule-1 - immunology; Nasal Mucosa - immunology; Oncorhynchus mykiss - immunology; Vascular Cell Adhesion Molecule-1 - immunology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.1600678

Mucosal surfaces require balancing different physiological roles and immune functions. To effectively achieve multifunctionality, mucosal epithelia have evolved unique microenvironments that create unique regional immune responses without impairing other normal physiological functions. Whereas examples of regional immunity are known in other mucosal epithelia, to date, no immune microenvironments have been described in the nasal mucosa, a site where the complex functions of olfaction and immunity need to be orchestrated. In this study we identified the presence of CD8α
cells in the rainbow trout (Oncorhynchus mykiss) nasal epithelium. Nasal CD8α
cells display a distinct phenotype suggestive of CD8
T cells with high integrin β
expression. Importantly, nasal CD8α
cells are located in clusters at the mucosal tip of each olfactory lamella but scattered in the neuroepithelial region. The grouping of CD8α
cells may be explained by the greater expression of CCL19, ICAM-1, and VCAM-1 in the mucosal tip compared with the neuroepithelium. Whereas viral Ag uptake occurred via both tip and lateral routes, tip-resident MHC class II
cells are located significantly closer to the lumen of the nasal cavity than are their neuroepithelial counterparts, therefore having quicker access to invading pathogens. Our studies reveal compartmentalized mucosal immune responses within the nasal mucosa of a vertebrate species, a strategy that likely optimizes local immune responses while protecting olfactory sensory functions.