Genetic targeting of intraepithelial mast cells

Project Summary/Abstract: Mast cells (MCs) expand within the airway epithelium during prevalent and burdensome human respiratory disease, including asthma and nasal polyposis, where they are thought to play a central role in disease pathobiology. The expanded intraepithelial MC compartment characteristic of Th2 high asthma correlates with disease severity and therapeutic targeting of this compartment improves patient outcomes, suggesting a central role in disease pathobiology. Despite this, the mechanism(s) through which intraepithelial mast cells participate in airway inflammation remain unclear, in part due to a lack of robust pre-clinical models to selectively target this MC subset in an in-vivo setting. This proposal describes the creation of a novel mouse strain in which tamoxifen-inducible cre recombinase coupled with a fluorescent reporter tag is selectively expressed within the lung by inflammation-expanded intraepithelial mast cells, termed mucosal mast cells (MMCs) in mice, and will use this strain to test the hypothesis that intraepithelial mast cells are an important contributor to airway inflammatory disease progression. Aim 1 of this study will validate reporter construct restriction to the MMC lineage across tissues and conduct a timecourse analysis of the dynamics of construct upregulation and its long-term maintenance within the lung MMCs compartment. Aim 2 will use our strain to generate inducible MMC knockout mice, which will then be used to test the degree to which MMC regulate pulmonary inflammation and airway hyperreactivity at two discrete phases of allergic lung inflammation. Completion of these aims will provide definitive evidence as to the importance of MMC in allergic lung inflammation and set the stage for future studies using this strain to both determine the mechanism(s) through which they influence lung inflammation and test their importance in other models of mucosal inflammation, such as food allergy and eosinophilic esophagitis.