Exhausted T cells (TEX) with reduced effector function are commonly observed in chronic infections and cancer. Their presence and role in autoimmune-mediated diseases such as inflammatory bowel disease (IBD) is unclear. This project will perform a detailed assessment of TEX in the peripheral blood and tissue of patients with IBD presenting with active disease and in remission using novel metrics of T cell exhaustion. To identify signals regulating TEX in IBD, T cell immunometabolism and cellular interaction partners in the inflamed microenvironment will be analysed. Understanding the role of TEX in autoimmunity has implications for diagnostics and immune-directed therapies.