TRPM5⁺microvillous tuft cells regulate neuroepithelial intrinsic olfactory stem cell proliferation

Abstract

integrating single-cell RNA sequencing and immunolocalization we define distinct markers of olfactory neuroepithelial cells, showing that Muc2 uniquely identifies sustentacular cells and Ncam1 is a robust mouse and human marker for OSNs. The enigmatic, transcriptionally uncharacterized subsets of olfactory microvillous cells (MVCs) correspond to nasal tuft cells and ionocytes in both mice and humans. Next we identify three morphologically, molecularly, and spatially distinct subsets of tuft cells: Nrgn+ MVC, Dclk1+ glandular and Gnat3+ respiratory tuft cells. While distinct, these subsets of tuft cells share a core machinery for allergen recognition and generation of the eicosanoid mediators cysteinyl leukotrienes. Single-cell analysis of the response to inhaled allergens revealed robust induction of olfactory stem cell proliferation, which is abolished by tuft cell-specific deletion of Ltc4s, required for cysteinyl leukotriene generation. Together our data provide high resolution characterization of epithelial cell diversity in the nose, uncovering a novel mechanism by which the mucosal response to allergens, specifically tuft cell-derived eicosanoids, regulates stem cell proliferation in the olfactory neuroepithelium.

Primary nasal viral infection rewires the tissue-scale memory response

“…Basal cells in the nasal mucosa give rise to epithelial cells reminiscent of pseudostratified epithelium found in the trachea (Davis and Wypych, 2021), but we and others have also captured several additional epithelial cell subsets not found in other parts of the airway. Our atlas validates recent work in mouse describing sustentacular cells, ionocytes, nasal tuft cells, and serous cells (Brann et al, 2020;Ualiyeva et al, 2022). Moreover, we describe for the first time several clusters of epithelial cells with undetermined function: (1) Scgb-b27+Cck+, (2) Meg3+MHC-II+, (3) Klk1+Fxyd2+, and (4) KNIIFE cells.…”

“…In addition to known subsets, we also identified unique clusters of epithelial cells potentially specific to the nasal mucosa and present in naïve mice and throughout primary infection that separated distinctly in UMAP space: Scgb-b27+Cck+, Klk1+Fxyd2+, Meg3+MHC-II+, and Krt13+Il1a+ cells. Epithelial clusters were differentially distributed across regions (Figure 3C): recently described nasal tuft cells, ionocytes, and Dclk1+ cells (Ualiyeva et al, 2022), as well as olfactory sensory neuron supportive sustentacular cells (Brann et al, 2020), were enriched in OM, whereas serous and glandular cells were specific to LNG.…”

“…The dataset was then divided into separate objects by cell type label for further subclustering. Following the same routine applied to the full dataset, clusters for each cell type were annotated with subset/state labels based on prior knowledge and previously published scRNAseq datasets of the nasal mucosa (Brann et al, 2020;Ualiyeva et al, 2022;Ziegler et al, 2021). After the first set of annotations in every cell type object, it was apparent that there were still intra-sample doublets present: mostly contaminating cell types, but also within cell type doublets (e.g., ionocyte/sustentacular doublets).…”