Investigating and Leveraging the Role of Tissue Transglutaminase 2 in Celiac Disease and Cancer

Transglutaminase 2 (TG2) is a calcium-dependent enzyme with diverse roles in tissue remodeling, immune activation, and disease pathology. In this dissertation, I investigate the regulation and consequences of TG2 enzymatic activity in two distinct immunologic contexts: autoimmunity and cancer. In the first part of this thesis, I investigate the early immunologic events that drive TG2 activation in celiac disease (CeD), an autoimmune enteropathy triggered by dietary gluten. Using a HLA-DQ2-restricted mouse model of CeD, I identify a defined temporal window in which intestinal TG2 activity emerges following gluten exposure. I show that inflammatory cues relevant to CeD pathogenesis—including IL-15 overexpression and reovirus infection—are each sufficient to induce robust TG2 activation in the small intestine. Furthermore, using a fluorogenic probe specific for catalytically active TG2, I demonstrate that CD103⁺ dendritic cells preferentially take up active TG2 in vivo under inflammatory conditions, supporting a model in which inflammation initiates TG2 activation and promotes the uptake of TG2-gluten complexes by antigen-presenting cells, thereby facilitating gluten antigen processing and presentation to CD4⁺ T cells. This work provides new mechanistic insight into the early molecular and cellular events that precede adaptive immune activation in CeD. In the second half of this thesis, I develop a therapeutic platform that exploits the tumor-restricted activation of TG2 to covalently anchor engineered cytokines to the tumor matrix. I apply this strategy to interleukin-7 (IL-7), creating a Transglutaminase Substrate Domain (TSD)-IL-7 fusion that enables local immune activation and demonstrates therapeutic efficacy as a monotherapy and in combination with chemotherapy or PD-1 blockade. This approach induces complete responses in an immunotherapy-refractory ovarian cancer model and significantly improves survival and tumor control in multiple murine tumor models. Mechanistically, TSD-IL-7 promoted T cell proliferation and antitumor cytokine and chemokine production in the tumor and tumor-draining lymph nodes, while reducing T cell exhaustion and promoting CD8+ central memory T cell development within the tumor. Together, these studies reveal novel insights into the biology of TG2 in inflammation and demonstrate its translational potential as a tool for targeted immunotherapy.