Our gut is constantly exposed to environmental harms, such as bacteria and dietary products, among others. The epithelium layer of our intestinal tract, which is the most exposed to the external world, contains a variety of immune cells, which likely play an important role in patrolling and defending our intestine. However, how these cells protect epithelial cells and the host from pathogens and other insults is still poorly understood. In this grant application, we aim to better understand how a specific subset of intraepithelial immune cells, known as gd T cells, contributes to gut homeostasis. We found that these cells are highly decreased in Crohn’s Disease patients, suggesting that they exert protective roles during disease. In addition, we found that they are heterogeneous and can crosstalk with either epithelial cells or other immune cells located deeper in the tissue. Herein, we plan to design functional experiments to better understand their role in the context of gut immune responses and how they affect surrounding epithelial or other immune cell types. In addition, we aim to identify if they derive from a common precursor or if they are highly diverse and whether this scenario is altered in CD.