Lung-Resident Memory Th2 Cells in Asthma

The objective of this study is to define the mechanisms whereby Th2-Trm persisting in the lung orchestrates a recall response to inhaled allergens. The investigators' central hypothesis is that Th2-Trm ignite allergic airway inflammation via a rapid and enhanced response to cognate antigen in the airway and the ability to recruit circulating Th2 cells (Th2-Tcr) to the sites of antigen presentation in the lung. Mechanistically, the investigators hypothesize that Th2-Trm co-localize with DCs expressing the Th2 cell-attracting chemokine CCL17 and after allergen re-challenge rapidly produce type 2 cytokines that initiate allergic inflammation and markedly enhance DC expression of CCL17. This increased CCL17 expression recruits Th2-Tcr cells from the blood to sites of antigen presentation where Th2-Tcr receive a "second touch" from cognate antigen loaded and activated DCs and become fully competent to amplify allergic inflammation. The investigators propose to use innovative experimental systems to define the function of Th2-Trm, including single cell RNA-seq analysis of human airway mucosal CD4+ T cells obtained via bronchial brushing. Specifically, the investigators propose to define the transcriptional phenotype of human lung Th2-Trm and Th2-Tcr. Defining the mechanisms regulating Th2-Trm function in the asthmatic airway has the potential to yield new therapeutic approaches for allergic asthma. Memory CD4+ T helper type 2 (Th2) cells are critical in promoting allergic asthma, the most common asthma endotype. The investigators propose to define the function of newly described lung-resident memory Th2 cells in driving recurrent allergic airway inflammation. The successful completion of the proposed study has the potential to focus new asthma therapies on specifically targeting the biology of lung-resident memory Th2 cells.