MHCII+ epithelial cells as potential determinants of airway allergy 2356

Description Airway epithelial cells (AECs) are the primary interface between the respiratory system and environmental exposures such as pathogens, allergens, and particulate matter. While AECs are not typically known as professional antigen-presenting cells, recent studies revealed AEC populations capable of antigen processing and presentation during viral and bacterial infections. However, MHCII expression by these AECs did not influence disease outcomes. Therefore, we hypothesized that MHCII expression on AECs may instead play a critical role in response to inhaled allergens, another significant environmental exposure. Our study demonstrates constitutive MHCII expression across several distinct AEC populations in the mouse lung via flow cytometry. In response to house dust mite (HDM), we observed increased MHCII expression and upregulation of costimulatory molecules in AECs. In addition, using fluorescently labeled HDM, we identified a unique MHCII+ basal AEC subpopulation that doubles in number upon allergen exposure and phagocytoses allergen in vivo. This observation also translates to humans, since bronchial epithelial cells from asthmatic patients also show dysregulated MHCII expression compared to controls. Our findings suggest the existence of a specific population of airway epithelial basal cells may act as an antigen-presenting cell in the context of allergy. The dysregulation of this process may modify the outcomes of allergic disease.