Type 2 Inflammation Drives an Airway Basal Stem Cell Program Through Insulin Receptor Substrate Signaling

BackgroundChronic rhinosinusitis with nasal polyposis (CRSwNP) is a type 2 (T2) inflammatory disease associated with an increased number of airway basal epithelial cells (BCs). Recent studies have identified transcriptionally distinct BCs, but functional data are lacking and the molecular pathways that support or inhibit human BC proliferation and differentiation are largely unknown.ObjectiveTo determine the role of T2 cytokines in regulating airway BCsMethodsSingle cell and bulk RNA-sequencing of sinus and lung airway epithelial cells was analyzed. Human sinus BCs were stimulated with IL-4 and IL-13 in the presence and absence of IL4R inhibitors. Confocal analysis of human sinus tissue and murine airway was performed. Murine BC subsets were sorted for RNA sequencing and functional assays. Fate labeling was performed in a murine model of tracheal injury and repair.ResultsHere we find two subsets of BCs in human and murine respiratory mucosa distinguished by the expression of BC adhesion molecule (BCAM). BCAM expression identifies airway stem cells among P63+KRT5+NGFR+ BCs. In the sinonasal mucosa, BCAMhiBCs expressingTSLP,IL33,CCL26,and the canonical BC transcription factorTP63are increased in patients with CRSwNP. In cultured BCs, IL-4/13 increases expression ofBCAMandTP63through an Insulin Receptor Substrate (IRS)-dependent signaling pathway that is increased in CRSwNP.ConclusionsThese findings establish BCAM as a marker of airway stem cells among the BC pool and demonstrate that airway epithelial remodeling in T2 inflammation extends beyond goblet cell metaplasia to the support of a BC stem state poised to perpetuate inflammation.CAPSULE SUMMARYType 2 cytokines drive an airway stem cell program through IRS signalingKEY MESSAGESTwo subsets of airway BCs have distinct transcriptional signatures and functionHigh levels of BCAM expression mark the earliest BC progenitorIL-4 and IL-13 upregulate BCAM and P63 in an IRS-dependent fashion which prevents BC differentiation to secretory epithelial cellsBCAMhiBCs are increased in CRSwNP