Dwyer, Alexander2024-06-052024-06-052022-04https://hdl.handle.net/11299/263716University of Minnesota Ph.D. dissertation. April 2022. Major: Microbiology, Immunology and Cancer Biology. Advisor: Brian Fife. 1 computer file (PDF); xiii, 194 pages.Autoimmune diabetes (AD) is a disease characterized by T cell-mediated destruction of the insulin-producing β cells within the islets of Langerhans of the endocrine pancreas. Upon recognition of β cell-specific autoantigen, self-reactive T cells of various specificities expand and migrate to pancreatic islets. Recently, a hybrid peptide derived from the insulin C-chain and chromogranin A (InsC-ChgA) was identified as the cognate antigen for the non-obese diabetic (NOD) mouse-derived diabetogenic BDC-2.5 CD4+ T cell clone, suggesting InsC-ChgA-specific T cells may contribute to disease. Epifluorescent microscopy of pancreatic islets is one approach by which islet T cell inflammation can be assessed in the course of disease altering therapies targeting InsC-ChgA-specific cells, yet most analytical techniques rely upon cumbersome manual estimation of islet infiltration. Importantly, little is known regarding the pathogenicity of InsC-ChgA-specific CD4+ T cells in NOD mice and how selective inhibition of these cells impacts cross-sectional T cell infiltrate area within the pancreatic islets. Here, we first describe a novel approach to achieve rapid, automated, unbiased, and quantifiable data regarding the distribution of islet infiltrating CD4+ and CD8+ T cells in NOD mice. We demonstrate the accurate detection of islet borders using convex hull islet modeling and quantification of T cell infiltrate by writing a macro using the freeware ImageJ. With this method, we assessed CD4+ and CD8+ T cell inflammation within the islets of different age groups of NOD mice progressing towards AD. As proof of technique, we identified significantly more T cell infiltration within convex hull-defined islets of non-diabetic 13-week and 17-week diabetic NOD mice compared to 4-week mice. Second, we focused on the InsC-ChgA-specific CD4+ T cell response in NOD mice and show rapid activation and expansion in neonates. We found that expansion of InsC-ChgA-specific cells requires early interactions with XCR1+ type 1 conventional dendritic cells, and InsC-ChgA-specific cells are clonally restricted with bias towards TRBV15 usage. We also show that adoptive transfer of polyclonal InsC-ChgA-specific cells into NOD.Rag1-/- mice induces AD. Further, spontaneous disease can be suppressed through weekly administration of an InsC-ChgA:I-Ag7-specific monoclonal antibody (mAb). Using the convex hull approach for quantification of T cell infiltration, we identified a substantial decrease in both CD4+ and CD8+ intra-islet infiltration in the nominally pre-diabetic period following InsC-ChgA:I-Ag7 mAb treatment. This thesis describes a novel methodology for the quantifiable assessment of T cell islet infiltration in NOD mice. Additionally, the data here establish the pathogenicity of InsC-ChgA-specific CD4+ T cells, and that immune responses to InsC-ChgA antigen are both necessary and sufficient for AD induction. These results form a framework for future interrogation of other hybrid peptide-specific T cell contributions to AD development in both mice and humans.enAutoantigenAutoimmunityDiabetesHybrid PeptideNeoantigenNODThesis or Dissertation