Type 2 Inflammation and Remodeling Elicited Through an LTE4/OXGR1-dependent pathway

PROJECT SUMMARY Tuft cells are a specialized epithelial cells (EpCs) that initiate airway type 2 inflammation (T2I) through their generation of IL-25 and pro-inflammatory lipid mediators, cysteinyl leukotrienes (CysLTs). We previously reported that airway tuft cells are indirectly activated by common aeroallergens through damage-associated molecular patterns (DAMPs), including the release of ATP and the activation of P2Y2 on tuft cells. Because tuft cells recognize tissue damage, and are detected in settings of airway injury in mouse and humans, we and others have speculated that they may have a role in lung repair, but thus far no such function has been demonstrated and the mechanism(s) by which tuft cells develop in the distal airways are unknown. Our preliminary data demonstrate an important feed forward loop by which tuft cells promote airway remodeling. We find that, in the setting of established inflammation, murine tracheal tuft cells generate CysLTs, activate several airway epithelial progenitor populations that express the leukotriene E4 receptor OXGR1, and drive aberrant airway remodeling. Importantly, we find that elements of the tuft cell and regenerative pathways seen in the murine trachea, are also expressed in allergen-challenged murine lung, and in the sinonasal mucosa of patients with the chronic rhinosinusitis with nasal polyposis (CRSwNP). This grant aims to define tuft cell and CysLT influence on wound repair in these settings, and to define the functional sequelae. To examine this, Aim 1 and 2 will use two murine models of tracheal and lung T2I. Several fate-labelled reporter mice will be tracked and crossed to null strains. Bulk and scRNA-seq will be used to define the altered molecular pathways in regenerating epithelium and several functional assays will be tested. Aim 3 will assess airway repair in patients with CRSwNP using scRNA-seq, spatial multiplexed fluorescent in situ hybridization, and ex vivo analysis. The resulting information will allow us to understand immune epithelial cross talk in the human airway and the role of CysLTs and OXGR1 in driving remodeling.