Type-2 Cytokine Regulation of Tuft Cell Differentiation in Salivary Glands - PROJECT SUMMARY Tuft cells are rare chemosensory epithelial cells that act as sentinels by sensing environmental cues and releasing mediators such as interleukin (IL)-25, acetylcholine, prostaglandins and leukotrienes. In intestine and airway, type-2 cytokines (IL-4, IL-13, IL-25) orchestrate tuft cell differentiation through a feed-forward circuit: IL- 25 from tuft cells activates group 2 innate lymphoid cells, which release IL-4 and IL-13 to drive further tuft cell emergence from progenitors, remodeling epithelium and amplifying type-2 tone. In salivary glands, our group has demonstrated the presence of tuft cells in mouse and human submandibular glands. Our preliminary studies show that mice lacking tuft cells have disrupted submandibular gland transcriptome, morphology and secretion indicating that tuft cells are required for epithelial integrity in this gland. We also observe increased tuft cell numbers in minor salivary gland biopsies from Sjögren’s disease patients and in Sjögren’s disease -like mouse model versus controls. Particularly, Sjögren’s disease is a systemic autoimmune disorder of the salivary and lacrimal glands that causes dry mouth and eye and predominantly affects women. Importantly, prior studies report that IL-4, IL-13, and IL-25 are elevated in Sjögren’s disease and contribute to epithelial damage, immune infiltration, and secretory dysfunction, yet whether these cytokines regulate tuft cell differentiation in salivary glands has never been tested. Therefore, this R03 will address this gap by testing the overall hypothesis that type-2 cytokines are involved in tuft cell differentiation in submandibular glands. Specifically, Aim 1 will define cytokine sufficiency and receptor requirements for tuft cell differentiation using mouse and human salivary gland organoids, integrating transcriptomic, imaging and functional assays. Aim 2 will validate these pathways in vivo using cytokine stimulation, receptor-deficient strains and autoimmune-prone mice, with spatial transcriptomics and immune profiling to resolve tuft cell-driven epithelial–immune niches. This study complements my ongoing R00, which examines tuft cell functions in salivary gland immunity, by focusing instead on the upstream pathways regulating tuft cell differentiation within submandibular glands. Together, the R00 and R03 will provide a coherent framework spanning tuft cell differentiation, function, and autoimmune dysregulation, and will generate the mechanistic insight and models needed to launch a future R01 targeting tuft cell–cytokine circuits in Sjögren’s disease.
