ABSTRACT: Type 1 Diabetes (T1D) is an autoimmune disease characterized by T cell-mediated destruction of insulin-producing pancreatic β-cells. The pathogenesis of T1D is not fully understood but involves development of autoantibodies (AAbs) followed by a progressive decline in first phase insulin response. Live imaging of T1D pancreatic slices has revealed β cell dysfunction irrespective of the acute presence or absence of CD3+ T cells. However, the mechanisms that drive this dysfunction in the prediabetic period remain unclear. In-situ longitudinal studies of human islet cell biology in the context of T1D are essentially impossible. Hence, we leveraged the availability of pancreas tissues from the Network for Pancreatic Organ donors with Diabetes (nPOD) program to phenotypically and transcriptionally characterize laser capture-microdissected islets across the natural history of T1D.
Project description:As early as one month of age, nonobese diabetic (NOD) mice feature pancreatic infiltration of autoreactive T lymphocytes, which destruct insulin-producing beta cells, producing autoimmune diabetes mellitus (T1D) within eightmonths. Thus, we hypothesized that during the development of T1D, the transcriptional modulation of immune reactivity genes may occur as thymocytes mature into peripheral T lymphocytes. The transcriptome of thymocytes and peripheral CD3+ T lymphocytes from prediabetic or diabetic mice analyzed through microarray hybridizations identified the differentially expressed genes.
Project description:Type 1 Diabetes (T1D) is considered to be a Th1 autoimmune disease characterised by an absolute lack of insulin caused by an autoimmune destruction of the insulin producing pancreatic beta cells. Th1 lymphocytes are responsible for the infiltration of the islets of Langerhans and for the cytokine release that supports cytotoxic (Tc) lymphocytes to mediate destruction of the beta cells. The preclinical disease stage is characterized by the generation of the self-reactive lymphocytes that infiltrate the pancreas and selectively destroy the insulin-producing beta cells present in the islets. Other cellular immune mechanisms regarding immunoregulation and antigen presentation and processing are involved in T1D pathogenesis as well. Our aim was to identify genes involved in the corresponding signalling cascades, especially those which may serve as promising diagnostic tools for the identification of persons in the prediabetic phase of the disease. We addressed the question by analysing gene expression profiles of freshly isolated peripheral blood mononuclear cells in type 1 diabetes patients, their first degree relatives divided according to their autoantibody status, and healthy controls. 9 T1D-patients versus 10 first degree relatives versus 10 healthy controls
Project description:Using an integrated approach to characterize the pancreatic tissue and isolated islets from a 33-year-old with 17 years of type 1 diabetes (T1D), we found donor islets contained β cells without insulitis and lacked glucose-stimulated insulin secretion despite a normal insulin response to cAMP-evoked stimulation. With these unexpected findings for T1D, we sequenced the donor DNA and found a pathogenic heterozygous variant in hepatocyte nuclear factor 1 alpha (HNF1A). In one of the first studies of human pancreatic islets with a disease-causing HNF1A variant associated with the most common form of monogenic diabetes, we found that HNF1A dysfunction leads to insulin-insufficient diabetes reminiscent of T1D by impacting the regulatory processes critical for glucose-stimulated insulin secretion and suggest a rationale for a therapeutic alternative to current treatment.
Project description:As early as one month of age, nonobese diabetic (NOD) mice feature pancreatic infiltration of autoreactive T lymphocytes, which destruct insulin-producing beta cells, producing autoimmune diabetesmellitus (T1D) within eight months. Thus, we hypothesized that during the development of T1D, the transcriptional modulation of immune reactivity genes may occur as thymocytes mature into peripheral T lymphocytes. The transcriptome of thymocytes and peripheral CD3+ T lymphocytes from prediabetic or diabetic mice analyzed through microarray hybridizations identified the differentially expressed genes.
Project description:Emerging evidence points towards an intricate relationship between the pandemic coronavirus disease 2019 (COVID-19) and diabetes. While diabetes is associated with an increased risk of severe COVID-19, new-onset type 1 diabetes (T1D) has been observed in COVID-19 patients, convoluting diabetes as both a risk factor and consequence of COVID-19. Understanding the mechanistic relationship between COVID-19 and T1D is an urgent and critical public health challenge. One pressing question is whether insulin-producing pancreatic β-cells can be infected by SARS-CoV-2, as T1D is a direct consequence of β-cell depletion. Here, we find that the SARS-CoV-2 receptor, ACE2 and its related entry factors, TMPRSS2, NRP1, and TRFC, are expressed in β-cells, with the latter two selectively present within β-cells. We discover that SARS-CoV-2 has selective cellular tropism for human pancreatic β-cells both ex vivo and in patients with COVID-19. We demonstrate that SARS-CoV-2 infection lowers the abundance of insulin within the pancreas, attenuates glucose-stimulated insulin secretion, and induces β-cell apoptosis. Finally, phosphoproteomic and pathway analysis suggests a SARS-CoV-2 stimulated signature for induction of apoptosis-associated signaling pathways in β-cells, similar to that seen in T1D. Taken together, our study demonstrates that SARS- CoV-2 can directly cause pancreatic islet impairment by killing β-cells, providing a mechanistic explanation for why T1D develops in COVID-19 patients.
Project description:Type 1 Diabetes (T1D) is considered to be a Th1 autoimmune disease characterised by an absolute lack of insulin caused by an autoimmune destruction of the insulin producing pancreatic beta cells. Th1 lymphocytes are responsible for the infiltration of the islets of Langerhans and for the cytokine release that supports cytotoxic (Tc) lymphocytes to mediate destruction of the beta cells. The preclinical disease stage is characterized by the generation of the self-reactive lymphocytes that infiltrate the pancreas and selectively destroy the insulin-producing beta cells present in the islets. Other cellular immune mechanisms regarding immunoregulation and antigen presentation and processing are involved in T1D pathogenesis as well. Our aim was to identify genes involved in the corresponding signalling cascades, especially those which may serve as promising diagnostic tools for the identification of persons in the prediabetic phase of the disease. We addressed the question by analysing gene expression profiles of freshly isolated peripheral blood mononuclear cells in type 1 diabetes patients, their first degree relatives divided according to their autoantibody status, and healthy controls.
Project description:Islet β-cell dysfunction and aggressive macrophage activity are early features in the pathogenesis of type 1 diabetes (T1D). 12/15-lipoxygenase (12/15-LOX) is induced in β cells and macrophages during T1D and produces pro-inflammatory lipids and lipid peroxides that exacerbate β-cell dysfunction and macrophage activity. Inhibition of 12/15-LOX provides a potential therapeutic approach to prevent glycemic deterioration in T1D. Two inhibitors recently identified by our groups through screening efforts, ML127 and ML351, have been shown to selectively target 12/15-LOX with high potency. Only ML351 exhibited no apparent toxicity across a range of concentrations in mouse islets, and molecular modeling suggested reduced promiscuity of ML351 compared to ML127. In mouse islets, incubation with ML351 improved glucose-stimulated insulin secretion in the presence of pro-inflammatory cytokines and triggered gene expression pathways responsive to oxidative stress and cell death. Consistent with a role for 12/15-LOX in promoting oxidative stress, its chemical inhibition reduced production of reactive oxygen species in both mouse and human islets in vitro. In a streptozotocin-induced model of T1D in mice, ML351 prevented the development of diabetes, with coincident enhancement of nuclear Nrf2 in islet cells, reduced β-cell oxidative stress, and preservation of β-cell mass. In the non-obese diabetic mouse model of T1D, administration of ML351 during the prediabetic phase prevented dysglycemia, reduced β-cell oxidative stress, and increased the proportion of anti-inflammatory macrophages in the insulitis. Our data provide the first evidence to date that small molecules that target 12/15-LOX can prevent progression of β-cell dysfunction and glycemic deterioration in models of T1D.
Project description:Type 1 diabetes (T1D) is a polygenic autoimmune disorder caused by autoreactive T cells that recognize pancreatic islet antigens and subsequently destroy insulin-producing β-cells. Pancreatic lymph nodes (PLN) are an essential site for the development of T1D, where tolerance to pancreatic self-antigens is first broken and the autoimmune responses are amplified. The purpose of this study was to identify candidate genes and pathways in the PLN that may contribute to the pathogenesis of T1D. Microarray analysis was performed on the PLN of human non-diabetic healthy controls (n=7) and at-risk autoantibody-positive subjects (n=13).
Project description:Type 1 diabetes (T1D) is a polygenic autoimmune disorder caused by autoreactive T cells that recognize pancreatic islet antigens and subsequently destroy insulin-producing β-cells. Pancreatic lymph nodes (PLN) are an essential site for the development of T1D, where tolerance to pancreatic self-antigens is first broken and the autoimmune responses are amplified. The purpose of this study was to identify candidate genes and pathways in the PLN that may contribute to the pathogenesis of T1D using a mouse model of T1D.
Project description:Type 1 diabetes (T1D) is a polygenic autoimmune disorder caused by autoreactive T cells that recognize pancreatic islet antigens and subsequently destroy insulin-producing β-cells. Pancreatic lymph nodes (PLN) are an essential site for the development of T1D, where tolerance to pancreatic self-antigens is first broken and the autoimmune responses are amplified. The purpose of this study was to identify candidate genes and pathways in the PLN that may contribute to the pathogenesis of T1D.