Immunohistochemical Detection, In Situ Distribution, and Comparison of Tuft Cells and Other Selected Components of Mucosal Immunity in Nasal Turbinates of Piglets Challenged with Rotavirus from Sows Fed Vitamin A-Deficient Diets with or Without Vitamin A Supplementation.

Tuft cells are a rare type of epithelial cell that are essential to regulate innate and adaptive immune responses. Mucosal immunity is also composed primarily of IgA produced by B cells that is secreted onto mucosal surfaces as secretory IgA via the polymeric immunoglobulin receptor (pIgR). The homing of B cells in lymphoid organs is mediated by certain adhesion receptors, such as α4β7 and chemokine receptor 9 (CCR9), that bind to the specific vascular ligands, mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1) and chemokine ligand 25 (CCL25), respectively. It is unclear whether tuft cells, MAdCAM-1, CCL25, and pIgR are present or expressed in the nasal cavities of pigs. Our study aimed to develop immunohistochemistry (IHC) or immunofluorescence (IF) staining for the detection of tuft cells, MAdCAM-1, CCL25, pIgR, and IgA- or IgG-positive cells in porcine nasal turbinates. The tissues were acquired from the piglets of two different treatment groups in our previous studies that investigated the impact of oral vitamin A supplementation (VA) on the maternal immunity of vitamin A-deficient (VAD) sows and the passive protection of their piglets against rotavirus A (RVA): (1) VAD + VA + RVA and (2) VAD + RVA piglets. Our IHC staining revealed that low numbers of advillin-positive, bottle-shaped cells that morphologically resemble tuft cells were present in the mucosal epithelium and the mucous duct or glands. There were also moderate to large amounts of MAdCAM-1 and CCL25 in the endothelial cells lining the vascular structures present in the lamina propria of nasal turbinates and moderate to large amounts of pIgR in the turbinate mucosal epithelium. Moderate to high numbers of IgA- or IgG-positive cells were present in the lamina propria. There were no differences in IF- or IHC-positive scores or the positive cell numbers of all parameters tested between VAD + VA + RVA and VAD + RVA piglets, suggesting little or no effect of VA on the parameters tested. Our study demonstrated the use of IHC/IF staining methods for the detection of tuft cells, MAdCAM-1, CCL25, pIgR, and IgA- or IgG-positive cells in porcine nasal turbinates, expanding our understanding of the in situ distribution and comparison in the nasal cavity of pigs born to the sows fed vitamin A-deficient diets with or without vitamin A supplementation.