Declines in beta-Cell Glucose Responsiveness Correlate with Loss of Glucose Metabolism during T1D Pathogenesis

Features of type 1 diabetes (T1D) include loss of first-phase insulin secretion in response to glucose, declining c-peptide, and glucose intolerance; indicating β cell dysfunction. Here, we investigate the mechanisms of this dysfunction with the hypothesis that immune dysregulation during the early stages of T1D development impacts β cell dysfunction in pathways affecting glucose metabolism. The live pancreas tissue slice (LPTS) model is ideal for the study of T1D pathogenesis due to its preservation of the pancreatic environment. LPTS were generated from organ donors without diabetes or autoantibodies (ND, n=9) , donors positive for one or more autoantibodies without a diagnosis of T1D (AAb+, n=6) , and donors with T1D (T1D, n=4) . Imaging studies were conducted to assess the impact of T cell infiltration on β cell function through Ca2+ imaging and slice perifusion. Islets from ND and AAb+ donors had no insulitis and exhibited Ca2+ responses to both high glucose (HG) and potassium chloride (KCl) . A majority of β cell+ islets in tissue from donors with T1D had infiltrating T cells with several having insulitis. Islet HG response from donors with T1D was heterogenous (∼50% failed to respond) while all T1D islets exhibited responses to KCl. Insulin secretion was significantly higher in LPTS from ND donors than in donors with T1D (p=0.0079) . To determine the basis for this loss of function, we assessed transcriptomics of islets within these cohorts. When comparing gene expression levels in islets from ND versus T1D, significant differences were observed in genes involved in glycolysis (GAPDH, p=3.27x10-21) , the citric acid cycle components (OGDH, p=1.88x10-18) , and the electric transport chain (F1FoATP synthase, p=2.69x10-13) . The decreased expression of glucose metabolism genes during T1D development along with the loss of β cell function in LPTS demonstrates β cell dysfunction before their demise and may be a contributory mechanism towards the pathogenesis of disease. Disclosure M.Huber: None. M.Slak rupnik: None. D.M.Drotar: None. H.Hiller: None. M.Beery: None. I.Kusmartseva: None. M.A.Atkinson: None. E.Phelps: Research Support; Immunocore, Ltd. C.E.Mathews: None. Funding National Institutes of Health (5T32DK108736-03) National Institutes of Health (PO1 AI42288)