Type 1 diabetes (T1D) is a disorder that arises following the autoimmune destruction of insulin producing pancreatic β-cells. Previous studies, including nearly 120 peer reviewed-articles supported by this P01 over the current grant cycle, have demonstrated that individuals with or at increased-risk for T1D display a series of innate and adaptive immunological abnormalities linked to genetypes at >150 risk-associated loci. Indeed, these efforts have identified a series of immune dysfunctions associated with T1D that are strongly influenced by genetics (e.g., loss/gain of function mutations, promoter/enhancer variants, shifts in exon usage) and appear to drive autoimunity. Yet the complex contributions of T1D-risk loci to these processes remain quite unclear. Thus, our goal in seeking renewal of this P01 is to elucidate the mechanisms by which T1D-associated variants across the genome (Project 1), and specifically (SH2B3 [Project 2], HLA-II region, SIRPG, CD226 [Project 3]), impart phenotypic and functional immune defects. The research proposed will collectively test two overall hypotheses— 1) the impact of T1D-risk variants will vary by tissue, cell subset and activation state, and 2) risk variants, cellular stress, and defects in immunologic pathways are key to engender the autoimmune destruction of pancreatic - cells that results in T1D. The three separate but highly interactive Projects have a strong history of sharing data, using innovative technologies, and assessing fresh and cryopreserved samples from well characterized human subjects with or at risk for T1D, as ascertained through two Core facilities: Core A– Administrative/Sample Acquisition and Core B– Biobank/Biostatistics/Bioinformatics. Project 1 will implement our novel pancreas slice culture system and TCR-redirected “avatars” to evaluate the impact of inflammation in the target organ. Project 2 will use genotype selected UFDI Study Bank samples (Core B), pancreas tissues, and differentiated gene- edited iPSCs to interrogate how SH2B3 allotypes impact innate immune cell function, T cell activation, and trafficking through inflamed vasculature. Project 3 proposes to study pancreatic lymph node (pLN), spleen, and peripheral blood to test the hypothesis that T1D-associated genetic risk variants alter the TCR repertoire and gene expression pathways in a cell- and tissue-restricted manner. These proposed studies are further supported by the rich environment for T1D research at the University of Florida that includes resources such as pancreatic and lymphoid tissue samples from the Network for Pancreatic Organ donors with Diabetes (nPOD), interactions with major clinical trial networks including T1D TrialNet, and special efforts related to the impact of race/genetic ancestry (made possible through highly active recruiting efforts) on T1D heterogeneity. The successes expected from the proposed studies should provide: 1) novel insights into the immune and genetic influences that contribut...