Project Summary/Abstract This proposal describes a 5-year plan to achieve the candidate’s goal of becoming an independent physician- scientist studying interactions between the airway epithelium and the type 2 immune system. With a comprehensive plan of coursework and hands-on training, guided by a skilled scientific advisory and mentoring team, and situated within the exceptional intellectual environment at UCSF, Dr. Kotas will utilize established, specialized tools and techniques from her mentor’s lab and become newly proficient in primary airway epithelial culture, translational studies using human tissues, and state-of-the-art transcriptional techniques. By the end of this project, she will possess a unique toolset that will differentiate her from her mentor and will have sufficient data to launch an independent research group while contributing new knowledge to the scientific community. The investigative purpose of this proposal is to elucidate how tuft cells—specialized epithelial cells with poorly understood function—influence the behavior of nearby epithelial and immune cells during chronic type 2 airway inflammation. As chronic allergic inflammation is the underlying cause of morbidity and mortality in millions of patients with diseases such as nasal polyps and type 2 high asthma, an improved understanding of the cells and molecules that contribute to these pathologies is needed to design new therapies. In preliminary data, Dr. Kotas finds that tuft cells in the chronically allergic upper airway environment adopt a distinct “allergic” phenotype characterized by increased production of prostaglandin E2 (PGE2). This is concurrent with a transcriptional signature of PGE2 on the neighboring epithelium, while in vitro, PGE2 stimulates epithelial fluid secretion. Transcriptional signatures of allergic tuft cells and PGE2 activation are also observed in the bronchus in type 2 high asthmatics, suggesting similar pathology throughout the allergically-inflamed respiratory tract. These findings urge further examination of tuft cells and tuft cell-derived PGE2 in allergic airway disease. In this proposal, Dr. Kotas will build upon her preliminary data to probe the effects of tuft cells and PGE2 on airway homeostasis. Aim 1 will use mouse cells in vitro and whole animal modeling in vivo to examine tuft cell- dependent alterations mucociliary movement and airway surface liquid composition. Aim 2 will examine the effects of tuft cells and PGE2 on the type 2 immune system in mouse models of allergic airway disease. And Aim 3 will return focus to human subjects and determine the phenotype and activation state of tuft cells in the lower airway in type 2 high asthma. Together, the proposed experiments will improve our fundamental understanding of how tuft cells contribute to allergic airway disease, and may identify new molecular and cellular targets for future therapy.