Role of Intraepithelial airway macrophages in lung homeostasis and disease

Candidate: Tristan Kooistra, MD is a physician-scientist at Massachusetts General Hospital (MGH) and Harvard Medical School (HMS). His post-doctoral research helped define pathologic cell circuits and interactions in airways of human subjects with asthma. Building on that work, this proposal investigates how epithelial-derived Notch signals promote maturation of airway macrophages. The short-term goals of this K08 award are to leverage his existing experience in innate immune signaling, type 2 immunity, and 3D imaging along with new cutting-edge research skills to address the role of Notch activation in airway macrophages and how this influences allergic responses. Dr. Kooistra’s long-term goal is to lead an independent research program investigating the role of airway macrophages in inflammatory airway diseases. Training Activities: Dr. Kooistra will perform the work outlined in this proposal at MGH mentored by Dr. Benjamin Medoff, an experienced mentor and expert in lung immunology. Drs. Eric Schmidt, Thorsten Mempel, Alexandra-Chloe Villani, and Carla Kim will serve on his advisory committee to provide further expertise in intravital microscopy, ‘omics’ methods, 3D co-culture modeling, and mechanisms of pulmonary inflammation. Dr. Kooistra will also complete didactic courses in immunology, biostatistics, and systems biology research and will take advantage of the collaborative and rich intellectual environment at MGH and HMS. Research: Asthma is a common disease resulting from the pathologic activation of multiple cell types within the conducting airways and is frequently driven by allergic inflammation to environmental antigens. Identification of immune regulatory pathways driven by cell-cell interactions in the airway mucosa can identify novel therapeutic targets. Our preliminary data establishes that airway epithelial basal stem cells supply tonic Notch activation signals to adjacent intraepithelial airway macrophages (IAMs) necessary to maintain their MHC-II expression. Moreover, depletion of IAMs or blockade of basal cell Notch signals results in reduced allergic airway inflammation. We hypothesize that Notch signaling from airway epithelial basal stem cells to IAMs determines IAM activation state and antigen-presenting capabilities to influence downstream T cell activation. To test this hypothesis, in Aim 1 we will determine how Notch activation influences IAM functional maturation at homeostasis using transgenic mouse modeling and single-cell RNA sequencing. In Aim 2 we will characterize the role of IAM Notch activation in the development of allergic airway inflammation using intravital microscopy and mouse modeling of asthma. We will leverage 3D airway co- cultures of human airway macrophages to extend these findings into human tissues. By combining murine models and primary human co-cultures this proposal will provide mechanistic insight into airway immunity with relevance to asthma as well as critical training for Dr. Kooistra’s development as a successful “bench-to- bedside” physician-scientist. Project Number: 1K08HL177151-01A1 | Fiscal Year: 2025 | NIH Institute/Center: National Heart Lung and Blood Institute (NHLBI) | Principal Investigator: Tristan Kooistra | Institution: MASSACHUSETTS GENERAL HOSPITAL, BOSTON, MA | Award Amount: $170,640 | Activity Code: K08 | Study Section: NHLBI Mentored Clinical and Basic Science Study Section[MCBS (MA)] View on NIH RePORTER: https://reporter.nih.gov/project-details/1K08HL17715101A1