Insulin-producing Beta Cells Research Articles

Early Intervention by Family Physicians to Delay Type 1 Diabetes.

Type 1 diabetes (T1D) is an autoimmune disease mediated by T cells that target and destroy insulin-producing beta cells. Individuals with genetic risk of T1D will progress at variable rates through 3 stages of immune activation and development of islet autoimmunity. Measuring pancreatic islet cell autoantibodies predicts risk for progression that can take weeks to years before the onset of T1D. Screening options available to family physicians can identify persons at risk or in the early stages of T1D, such as first- and second-degree relatives or those with a family history of autoimmune disorders, to ultimately offer proven interventions that may delay or prevent the condition. Screening can reduce emergency room visits, hospitalizations, and intensive care unit admissions for diabetic ketoacidosis, which can be fatal, and can educate and prepare individuals and families for a smoother transition to insulin therapy when necessary. Recent advances in technology and understanding of the immune pathogenesis of T1D has resulted in emerging disease-modifying therapies that are changing how family physicians approach delaying and potentially preventing or reversing the disease.

283-OR: ADA Presidents' Select Abstract: An Isogenic hPSC-Based Platform for Functional Interrogation of the Role of Multiple T2D-Associated Genes in Pancreatic Beta-Cell Failure

Type 2 diabetes (T2D) mellitus is a complex polygenic disease. Multiple genome-wide association studies (GWAS) have identified hundreds of T2D-related genetic variants, the vast majority of which are non-coding. Pinpointing the actual causal variants and their target gene transcripts has been challenging. Building on recent advances in CRISPR technology and protocols that allow differentiation into functional pancreatic beta cells, we created isogenic hPSCs encompassing knockout (KO) mutations in 20 GWAS-identified T2D risk genes, and systematically examined their roles in beta cell differentiation, insulin production, glucose response, and apoptosis. As a result, loss of TCF7L2, HNF4A, TLE4, TGFB1, GIPR and COBLL1 severely impaired the differentiation capacities of hPSCs into functional beta cells and over half of the 20 T2D genes shared implications in beta cell dysfunctions including decreased insulin content, impaired insulin secretion and high susceptibility to lipotoxicity. Next, we sorted beta cells from each KO and performed RNA-seq and ATAC-seq assays. An integrative analysis revealed KO of HNF4A, HNF1A, ABCC8, KCNJ11, TLE4 and WDR13 resulted in extensive transcriptomic and epigenetic changes in the beta cells. We identify that KO of HNF4A results in dramatic expressional changes of dozens of known T2D effector genes and additional ones critical to beta cell functions and biology. An analysis of T2D GWAS credible set of SNPs using ATAC-seq and RNA-seq coupled with functional assays, helped us to nominate a single likely T2D causal SNP (rs7132908) at FAIM2 locus. Finally, a correlation analysis of gene expression levels and insulin content across KO lines identified 1,867 differential genes including PCSK1N that likely serves as a hub gene by mediating insulin production in beta cells. This study thus offers a powerful strategy to interrogate shared molecular pathways among multiple risk genes for diabetes. Disclosure D.Xue: None. J.Vandana: None. A.Chong: None. F.S.Collins: None. S.Chen: Consultant; Vesalius Therapeutics, Stock/Shareholder; Oncobeat Theraputics. N.Narisu: None. T.Yan: None. M.Zhang: None. C.Grenko: None. X.Tang: None. J.Zhu: None. L.L.Bonnycastle: None. M.Erdos: None. Funding American Diabetes Association (9-22-PDFPM-06 to D.X.)

278-LB: The Effect of Combining Very-Low-Calorie Diet with Semaglutide on Beta-Cell Function in Individuals with Type 2 Diabetes

Type 2 diabetes (T2D) is characterised by the loss of the first phase response of insulin-producing pancreatic beta cells. Recently, Very-low calorie diets (VLCD - defined as less than 800 kilocalories per day) have been shown to restore this first phase response to induce remission of T2D, while Glucagon-like peptide-1 agonists also improve the first phase response by enhancing postprandial insulin secretion. Here, we present interim results of an investigation exploring the effect of combining these two interventions on beta cell function, in individuals with T2D. Eighteen individuals with T2D and body mass index >27kg.m-2 were randomly allocated into 3 groups: i) Semaglutide (S), ii) VLCD (V), and iii) Semaglutide-plus-VLCD (SV). Semaglutide was administered once weekly gradually up titrated to a maximum dose of 1mg and VLCD regime was provided by LighterLife® total meal replacement. Beta cell function was assessed using intravenous glucose tolerance tests (IVGTT) performed at baseline and 12 weeks. First-phase insulin response was calculated as the incremental area under the suprabasal plasma insulin concentration curve during 0-10 minutes of the IVGTT (µU.min.ml-1). Data were analysed using GraphPad Prism 9.5.0 (La Jolla, USA). All groups were equally matched at baseline. Mean weight loss was 6.4, 14.1 and 14.9 kg in S, V and SV, respectively. A significant improvement in first phase response was observed in all groups (S: +398.5; V: +88.4; SV: +547.8 µU.min.ml-1, all p<0.05 vs. baseline). At 12 weeks, first phase response in SV was significantly higher than in V (583.9 vs. 169.2 µU.min.ml-1 respectively, p<0.05). These data suggest that combination of VLCD and Semaglutide results in a significantly greater improvement in first phase response than VLCD alone. This approach could result in a more robust remission of T2D in the longer-term, and may have important implications for the future design of interventions for the clinical management of T2D. Disclosure O. Anyiam: None. B. E. Phillips: None. D. J. Wilkinson: None. K. Smith: None. P. J. Atherton: None. I. R. Idris: None. Funding Medical Research Council Confidence in Concept Scheme

295-OR: Mechanisms of Antigen-Specific Immunotherapy following Tolerance Induction to a CD4 Hybrid Insulin Peptide Epitope and the Impact on CD8 T Cell Dysfunction

Type 1 diabetes is the culmination of T cell mediated autoimmunity resulting in the destruction of insulin-producing beta cells. Islet-derived hybrid insulin peptides (HIPs), recognized by autoreactive CD4 T cells, are likely dominant T cell epitopes in the NOD mouse model of autoimmune diabetes. The 2.5HIP is formed by the fusion of a fragment of insulin C-peptide with a natural cleavage product of chromogranin A, generating a neoepitope. When the 2.5HIP was delivered as an immunotherapy on tolerance inducing PLG-nanoparticles, islet grafts functioned longer in transplanted, diabetic NOD mice. Tolerance induction to this single neoepitope induced dysfunctional cytokine production in autoreactive CD4 and CD8 T cells specific for other known islet antigens. Here we used both prediabetic NOD mice and diabetic transplant recipients to examine mechanisms of peripheral tolerance induction to a HIP. Using the Tiger IL10-GFP reporter mouse, we observed a substantial increase in the proportion of (CD25+) Treg and (CD25-) Tr1 2.5HIP tetramer+ CD4 T cells that expressed IL10 in the islets, spleen, and draining lymph node of 2.5HIP nanoparticle treated mice. Autoreactive, IGRP tetramer+ CD8 T cells displayed a trafficking defect and accumulated in secondary lymphoid tissue with a concomitant reduction within islets. The proportion of cytolytic, CX3CR1+ IGRP tetramer+ CD8 T cells that infiltrated islets was also reduced. IL10 generated by both Treg and Tr1 2.5HIP tet+ T cells may directly suppress IGRP tetramer+ CD8 T cells or suppress an intermediate cell type such as a dendritic cell, causing CD8 T cell dysfunction. Examining how antigen-specific immunotherapies suppress multiple autoreactive T cells specificities may help inform future therapies without the need for immunosuppression. Disclosure J.E.Dilisio: None. R.L.Baker: None. K.M.Haskins: None. Funding National Institutes of Health (5T32DK120520-03, 2R01DK081166-11); JDRF (2-SRA-2020-907-S-B)

1738-P: Instrument-Free Single-Cell Resolution of Transcriptome in Mouse Pancreatic Islet Cells

Type 1 diabetes is characterized by an almost complete depletion of insulin-producing beta cells. Thus, regeneration of beta cells through beta-cell neogenesis represents a major therapeutic strategy to cure the disease. We previously reported a mouse model of severe insulin resistance that leads to high insulin secretion and massive beta-cell neogenesis. To understand the origins of the newly formed beta cells and the genic programs involved in high insulin secretion, we aimed at defining the pancreatic islet cells transcriptome at high resolution cell by cell. Here, we tested the compatibility of the novel instrument-free 3’ single-cell RNA-sequencing benchtop kit Asteria™, recently released by Scipio bioscience (Paris, France), on pancreatic islet cells isolated from adult mice, which underwent cell dissociation by trypsin treatment. In the Asteria™ procedure, differently from the microfluidic-based single-cell one, coupling of solid polymer-barcoded beads and cells occurs in homogenous phase in a reversible hydrogel named RevGel™. Such conditions are claimed by the vendor to be causing less mechanical stress to cells for an expected more preserved transcriptome. Successive steps were classic molecular biology and bioinformatic analysis using Scipio bioscience’s data analysis cloud-based software Cytonaut™. We profiled the transcriptome of 938 single cells from healthy mice and identified a total of 12 cell subtypes. SingleR annotation based on reference data revealed all the major cell types commonly described in the literature, including a well-represented beta cell population and some rare cell types such as ductal and stellate cells. We demonstrate 3’ single-cell RNA-sequencing using Scipio bioscience’s kit Asteria™ as an effective strategy to dissect the heterogeneity and the complexity of mouse pancreatic islets and identify the gene expression signatures of each cell. Disclosure D.G.Dimitrova: None. A.Liboz: None. S.Lipin: None. C.Beaupere: None. N.Roblot: None. J.Komatsu: None. G.Guillemain: None. B.Blondeau: None.

296-OR: Submicron Ultrasound Contrast Agents as Therapeutic Delivery Vehicles in Type 1 Diabetes

Type 1 diabetes (T1D) is characterized by immune-mediated destruction of insulin-producing beta cells resulting in severe hyperglycemia if untreated. Prior work has shown that islet microvasculature becomes hyperpermeable during presymptomatic T1D, allowing for ‘nanobubble (NB)’ submicron ultrasound contrast agents to accumulate in immune-infiltrated islets, which can be quantified using ultrasound contrast. We investigated the utility of these lipid-shelled NBs as peptide delivery vehicles to provide islet-targeted delivery, for acoustically driven therapeutic release and where therapeutic delivery can be visualized in real-time with ultrasound. We developed this platform to enhance efficacy of insulin peptide mimotopes, which can promote the expansion of anti-inflammatory regulatory T cells (Tregs) and prevent T1D in mice. We modified insulin B:9-23 peptides with a palmitoyl fatty acid tail to incorporate in the NB lipid shell. NBs accumulated specifically in NOD islets and not in other abdominal organs or NOD-SCID (control) islets (p < 0.0001). We found that palmitoylation enhanced peptide retention in NBs (p < 0.001) and is essential for delivery to NOD islets (p < 0.0001), where the extent of peptide delivery correlates with extent of insulitis (p < 0.05). Peptide incorporation did not affect NB echogenicity (in vitro and in vivo), ability to burst, and size distribution. Palmitoylation and incorporation in NBs does not affect the ability for peptide-pulsed antigen presenting cells to stimulate insulin-reactive T cells in vitro (p < 0.0001). Finally, NOD mice treated with peptide-NBs had a higher proportion of Tregs amongst insulin-reactive CD4+ T cells in islets, as compared to mice treated with NBs or peptide alone (p < 0.05). This serves as an important proof-of-principle for the usage of NBs for targeted peptide delivery and has the potential to improve therapeutic intervention in T1D. Disclosure M.Ciccaglione: None. K.Mcdaniel: None. A.W.Michels: Stock/Shareholder; Immnomolecular Therapeutics. A.A.Exner: None. R.K.Benninger: None. Funding National Institute of Diabetes and Digestive and Kidney Diseases (R01DK102950, R01DK106412, P30DK116073, T32DK120520); National Center for Advancing Translational Sciences (TL1TR002533); JDRF (1-INO-2017-435-A-N); University of Colorado

Сахарный диабет 1-го типа: особенности дифференциальной диагностики

Type 1 diabetes mellitus is a condition caused by autoimmune damage to insulin–producing beta cells of the pancreatic islets, leading to endogenous insulin deficiency. Despite the sufficient knowledge of the disease and the availability of clinical recommendations for substitution therapy, the number of patients with this pathology is growing worldwide. At the same time, their cohort is very heterogeneous, including amid different etiology, concomitant genetic background, variations in the manifestation of the disease and severity. In this regard, traditional ideas about type 1 diabetes mellitus are being questioned, which requires special attention when managing patients with a clinical picture of the disease that differs from the traditional one. The article presents a clinical case of type 1 diabetes mellitus in a young patient, which demonstrates the importance of a personalized approach to the diagnosis and treatment of diabetic patients with a "non-classical" history.

Inflammation versus regulation: how interferon-gamma contributes to type 1 diabetes pathogenesis.

Type 1 diabetes is an autoimmune disease with onset from early childhood. The insulin-producing pancreatic beta cells are destroyed by CD8+ cytotoxic T cells. The disease is challenging to study mechanistically in humans because it is not possible to biopsy the pancreatic islets and the disease is most active prior to the time of clinical diagnosis. The NOD mouse model, with many similarities to, but also some significant differences from human diabetes, provides an opportunity, in a single in-bred genotype, to explore pathogenic mechanisms in molecular detail. The pleiotropic cytokine IFN-γ is believed to contribute to pathogenesis of type 1 diabetes. Evidence of IFN-γ signaling in the islets, including activation of the JAK-STAT pathway and upregulation of MHC class I, are hallmarks of the disease. IFN-γ has a proinflammatory role that is important for homing of autoreactive T cells into islets and direct recognition of beta cells by CD8+ T cells. We recently showed that IFN-γ also controls proliferation of autoreactive T cells. Therefore, inhibition of IFN-γ does not prevent type 1 diabetes and is unlikely to be a good therapeutic target. In this manuscript we review the contrasting roles of IFN-γ in driving inflammation and regulating the number of antigen specific CD8+ T cells in type 1 diabetes. We also discuss the potential to use JAK inhibitors as therapy for type 1 diabetes, to inhibit both cytokine-mediated inflammation and proliferation of T cells.

Investigating immune profile by CyTOF in individuals with long-standing type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease caused by T-cell mediated destruction of pancreatic beta cells. Eosinophils are found in pancreatic tissue from individuals with T1D. Eosinophilic suppression of T cells is dependent of the protein galectin-10. Little is known when it comes to the role of eosinophil granulocytes in type 1 diabetes. Here we show that individuals with long-standing T1D had lower levels of galectin-10hi eosinophils and a subgroup of galectin-10hi eosinophils were entirely absent in all T1D patients. In addition, 7% immature eosinophils were present in the circulation of T1D patients whereas 0.8% in healthy individuals. Furthermore, higher levels of CD4+CD8+ T cells and Th17 cells were observed in patients with T1D. Blood samples from 12 adult individuals with long-standing T1D and 12 healthy individuals were compared using cytometry by time-of-flight. Lower levels of galectin-10hi eosinophils, which are potent T cell suppressors, in individuals with T1D could indicate that activated T cells are enabled to unrestrictedly kill the insulin producing beta cells. This is the first study showing absence of galectin-10hi eosinophilic subgroup in individuals with T1D compared with healthy controls. This study is a first important step toward unraveling the role of the eosinophils in patients with T1D.

Replenishable prevascularized cell encapsulation devices increase graft survival and function in the subcutaneous space.

Beta cell replacement therapy (BCRT) for patients with type 1 diabetes (T1D) improves blood glucose regulation by replenishing the endogenous beta cells destroyed by autoimmune attack. Several limitations, including immune isolation, prevent this therapy from reaching its full potential. Cell encapsulation devices used for BCRT provide a protective physical barrier for insulin-producing beta cells, thereby protecting transplanted cells from immune attack. However, poor device engraftment posttransplantation leads to nutrient deprivation and hypoxia, causing metabolic strain on transplanted beta cells. Prevascularization of encapsulation devices at the transplantation site can help establish a host vascular network around the implant, increasing solute transport to the encapsulated cells. Here, we present a replenishable prevascularized implantation methodology (RPVIM) that allows for the vascular integration of replenishable encapsulation devices in the subcutaneous space. Empty encapsulation devices were vascularized for 14 days, after which insulin-producing cells were inserted without disrupting the surrounding vasculature. The RPVIM devices were compared with nonprevascularized devices (Standard Implantation Methodology [SIM]) and previously established prevascularized devices (Standard Prevascularization Implantation Methodology [SPVIM]). Results show that over 75% of RPVIM devices containing stem cell-derived insulin-producing beta cell clusters showed a signal after 28 days of implantation in subcutaneous space. Notably, not only was the percent of RPVIM devices showing signal significantly greater than SIM and SPVIM devices, but the intraperitoneal glucose tolerance tests and histological analyses showed that encapsulated stem-cell derived insulin-producing beta cell clusters retained their function in the RPVIM devices, which is crucial for the successful management of T1D.

DYRK1A inhibitors leucettines and TGF-β inhibitor additively stimulate insulin production in beta cells, organoids, and isolated mouse islets.

The decreased β-cell mass and impaired β-cell functionality are the primary causes of diabetes mellitus (DM). Nevertheless, the underlying molecular mechanisms by which β-cell growth and function are controlled are not fully understood. In this work, we show that leucettines, known to be DYRK1A kinase inhibitors, can improve glucose-stimulated insulin secretion (GSIS) in rodent β-cells and isolated islets, as well as in hiPSC-derived β-cells islets. We confirm that DYRK1A is expressed in murine insulinoma cells MIN6. In addition, we found that treatment with selected leucettines stimulates proliferation of β-cells and promotes MIN6 cell cycle progression to the G2/M phase. This effect is also confirmed by increased levels of cyclin D1, which is highly responsive to proliferative signals. Among other leucettines, leucettine L43 had a negligible impact on β-cell proliferation, but markedly impair GSIS. However, leucettine L41, in combination with LY364947, a, a potent and selective TGF-β type-I receptor, significantly promotes GSIS in various cellular diabetic models, including MIN6 and INS1E cells in 2D and 3D culture, iPSC-derived β-cell islets derived from iPSC, and isolated mouse islets, by increased insulin secretion and decreased glucagon level. Our findings confirm an important role of DYRK1A inhibitors as modulators of β-cells function and suggested a new potential target for antidiabetic therapy. Moreover, we show in detail that leucettine derivatives represent promising antidiabetic agents and are worth further evaluation, especially in vivo.

Islet Autoantibodies to Pancreatic Insulin-Producing Beta Cells in Adolescent and Adults with Type 1 Diabetes Mellitus: A Cross-Sectional Study.

(1) Background: Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease caused by the destruction of pancreatic insulin-producing beta cells. T1D is one of the most common endocrine and metabolic disorders occurring in children. Autoantibodies against pancreatic insulin-producing beta cells are important immunological and serological markers of T1D. Zinc transporter 8 autoantibody (ZnT8) is a recently identified autoantibody in T1D; however, no data on ZnT8 autoantibody in the Saudi Arabian population have been reported. Thus, we aimed to investigate the prevalence of islet autoantibodies (IA-2 and ZnT8) in adolescents and adults with T1D according to age and disease duration. (2) Methods: In total, 270 patients were enrolled in this cross-sectional study. After meeting the study's inclusion and exclusion criteria, 108 patients with T1D (50 men and 58 women) were assessed for T1D autoantibody levels. Serum ZnT8 and IA-2 autoantibodies were measured using commercial enzyme-linked immunosorbent assay kits. (3) Results: IA-2 and ZnT8 autoantibodies were present in 67.6% and 54.6% of patients with T1D, respectively. Autoantibody positivity was found in 79.6% of the patients with T1D. Both the IA-2 and ZnT8 autoantibodies were frequently observed in adolescents. The prevalence of IA-2 and ZnT8 autoantibodies in patients with a disease duration < 1 year was 100% and 62.5%, respectively, which declined with an increase in disease duration (p < 0.020). Logistic regression analysis revealed a significant relationship between age and autoantibodies (p < 0.004). (4) Conclusions: The prevalence of IA-2 and ZnT8 autoantibodies in the Saudi Arabian T1D population appears to be higher in adolescents. The current study also showed that the prevalence of autoantibodies decreased with disease duration and age. IA-2 and ZnT8 autoantibodies are important immunological and serological markers for T1D diagnosis in the Saudi Arabian population.

Teplizumab Therapy to Delay the Onset of Type 1 Diabetes.

Type 1 diabetes mellitus (T1DM) is an autoimmune disease that results in the destruction of insulin-producing pancreatic beta cells. The incidence and prevalence of T1DM are increasing, making this one of the most common diseases of childhood. The disease is associated with significant morbidity and mortality with patients experiencing reduced quality of life and decreased life expectancy compared with the general population. Patients become dependent on exogenous insulin which has been the primary treatment since its first clinical use over 100 years ago. Although there have been advancements in glucose monitoring technology and insulin delivery devices, most patients fail to meet glycemic targets. Research has therefore focused on different treatment options to delay or prevent disease progression. Monoclonal antibodies have previously been utilized to suppress the immune response following an organ transplant and were subsequently studied for their ability to treat autoimmune diseases. Teplizumab, a monoclonal antibody (manufactured by Provention Bio and marketed as Tzield), was recently approved by the Food and Drug Administration as the first preventative treatment for T1DM. The approval came after a 3-decade history of research and development. This article provides an overview of the discovery and mechanism of action of teplizumab, as well as the clinical trials that led to its approval.

NET Proteome in Established Type 1 Diabetes Is Enriched in Metabolic Proteins.

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by a T-cell-mediated destruction of the pancreatic insulin-producing beta cells. A growing body of evidence suggests that abnormalities in neutrophils and neutrophil extracellular trap (NET) formation (NETosis) are associated with T1D pathophysiology. However, little information is available on whether these changes are primary neutrophil defects or related to the environmental signals encountered during active disease. In the present work, the NET proteome (NETome) of phorbol 12-myristate 13-acetate (PMA)- and ionomycin-stimulated neutrophils from people with established T1D compared to healthy controls (HC) was studied by proteomic analysis. Levels of NETosis, in addition to plasma levels of pro-inflammatory cytokines and NET markers, were comparable between T1D and HC subjects. However, the T1D NETome was distinct from that of HC in response to both stimuli. Quantitative analysis revealed that the T1D NETome was enriched in proteins belonging to metabolic pathways (i.e., phosphoglycerate kinase, glyceraldehyde-3-phosphate dehydrogenase, and UTP-glucose-1-phosphate uridylyltransferase). Complementary metabolic profiling revealed that the rate of extracellular acidification, an approximate measure for glycolysis, and mitochondrial respiration were similar between T1D and HC neutrophils in response to both stimuli. The NETome of people with established T1D was enriched in metabolic proteins without an apparent alteration in the bio-energetic profile or dysregulated NETosis. This may reflect an adaptation mechanism employed by activated T1D neutrophils to avoid impaired glycolysis and consequently excessive or suboptimal NETosis, pivotal in innate immune defence and the resolution of inflammation.

Suppression of IGRP-specific CD8 T cells following induction of tolerance to a Hybrid Insulin Peptide CD4 neoepitope

Abstract An autoimmune-mediated death of insulin-producing beta cells, orchestrated by effector CD4 and CD8 T cells that recognize islet antigens, results in Type 1 Diabetes. A dominant CD4 islet autoantigen in the NOD mouse model of autoimmune diabetes is a neoepitope termed the 2.5 Hybrid Insulin Peptide (2.5HIP). By delivering the 2.5HIP as an antigen-specific immunotherapy on tolerogenic PLG-nanoparticles, islet grafts in diabetic NOD mice survived longer and cytokine production in autoreactive CD4 and CD8 T cells was suppressed, including the well-studied IGRP tetramer+ (tet+) CD8 T cells. Using both diabetic transplant recipients and prediabetic NOD mice treated with 2.5HIP nanoparticles, we examined mechanisms of peripheral tolerance induction to a dominant CD4 neoepitope and the impact on the function of IGRP CD8 T cells. Following induction of tolerance to the 2.5HIP, there was an increase in dysfunctional surface marker expression (PD1+ TIM3+) on effector 2.5HIP tet+ CD4 T cells in the spleen of treated mice. Along with a decrease in effector function, we observed an increase in the fraction of both Treg and Tr1 2.5HIP tet+ T cells expressing IL10 in the islets, spleen, and draining lymph nodes of tolerized mice. Concurrently, IGRP tet+ CD8 T cells accumulated in the draining lymph nodes and were less able to traffic and infiltrate islets. Of the IGRP tet+ cells that entered islets, there were fewer cytolytic CX 3CR1 +effector cells in tolerized mice. The robust functional increase in both Treg and Tr1 2.5HIP tet+ T cells may provide a potential mechanism for the accumulation of IGRP tet+ CD8 T cells in the draining lymph node and explain their inefficient trafficking into, and function within, islets following tolerance induction. NIH - T32 5T32DK120520-03, R01 2R01DK081166-11) JDRF 2-SRA-2020-907-S-B

Induction of a single dose of streptozotocin (50 mg) in rat model causes insulin resistance with type 2 diabetes mellitus.

Streptozotocin (STZ) is a broad-spectrum antibiotic that is toxic to the insulin-producing beta cells of the pancreatic islets. STZ is currently used clinically for the treatment of metastatic islet cell carcinoma of the pancreas and the induction of diabetes mellitus (DM) in rodents. So far, there has been no previous research to show that STZ injection in rodents causes insulin resistance in type 2 diabetes mellitus (T2DM). The purpose of this study was to determine if rats (Sprague-Dawley) developed type 2 diabetes mellitus (insulin resistance) after 72 h of intraperitoneal administration of 50 mg/kg STZ. Rats with fasting blood glucose levels above 11.0 mM, 72 h post-STZ induction, were used. The body weight and plasma glucose levels were measured every week throughout the 60-day treatment period. The plasma, liver, kidney, pancreas, and smooth muscle cells were harvested for antioxidant, biochemical analysis, histology, and gene expression studies. The results revealed that STZ was able to destroy the pancreatic insulin-producing beta cell, as evidenced by an increase in plasma glucose level, insulin resistance, and oxidative stress. Biochemical investigation indicates that STZ can generate diabetes complications through hepatocellular damage, elevated HbA1c, kidney damage, hyperlipidemia, cardiovascular damage, and impairment of the insulin-signaling pathway.

A mechanistic modeling platform of SGLT2 inhibition: Implications for type 1 diabetes.

Type 1 diabetes mellitus (T1DM) is an autoimmune disease characterized by abnormally high blood glucose concentrations due to dysfunction of the insulin-producing beta-cells in the pancreas. Dapagliflozin, an inhibitor of renal glucose reabsorption, has the potential to improve often suboptimal glycemic control in patients with T1DM through insulin-independent mechanisms and to partially mitigate the adverse effects associated with long-term insulin administration. In this work, we have adapted a systems pharmacology model of type 2 diabetes mellitus to describe the T1DM condition and characterize the effect of dapagliflozin on short- and long-term glycemic markers under various treatment scenarios. The developed platform serves as a quantitative tool for the in silico evaluation of the insulin-glucose-dapagliflozin crosstalk, optimization of the treatment regimens, and it can be further expanded to include additional therapies or other aspects of the disease.

Association between Toxoplasma gondii Infection and Type-1 Diabetes Mellitus: A Systematic Review and Meta-Analysis.

Type-1 diabetes, an autoimmune disease characterized by damage to pancreatic insulin-producing beta cells, is associated with adverse renal, retinal, cardiovascular, and cognitive outcomes, possibly including dementia. Moreover, the protozoal parasite Toxoplasma gondii has been associated with type-1 diabetes. To better characterize the association between type-1 diabetes and Toxoplasma gondii infection, we conducted a systematic review and meta-analysis of published studies that evaluated the relationship between type-1 diabetes and Toxoplasma gondii infection. A random-effects model based on nine primary studies (total number of participants = 2655) that met our inclusion criteria demonstrated a pooled odds ratio of 2.45 (95% confidence interval, 0.91-6.61). Removing one outlying study increased the pooled odds ratio to 3.38 (95% confidence interval, 2.09-5.48). These findings suggest that Toxoplasma gondii infection might be positively associated with type-1 diabetes, although more research is needed to better characterize this association. Additional research is required to determine whether changes in immune function due to type-1 diabetes increase the risk of infection with Toxoplasma gondii, infection with Toxoplasma gondii increases the risk of type-1 diabetes, or both processes occur.

Type 1 Diabetes Mellitus and Autoimmune Diseases: A Critical Review of the Association and the Application of Personalized Medicine.

Type 1 Diabetes Mellitus (T1DM) is a common hyperglycemic disease characterized by the autoimmune destruction of insulin-producing beta cells of the pancreas. Various attempts have been made to understand the complex interplay of genetic and environmental factors which lead to the development of the autoimmune response in an individual. T1DM is frequently associated with other autoimmune illnesses, the most common being autoimmune thyroid disorders affecting more than 90% of people with T1D and autoimmune disorders. Antithyroid antibodies are present in around 20% of children with T1D at the start of the illness and are more frequent in girls. Patients with T1DM often have various other co-existing multi-system autoimmune disorders including but not limited to thyroid diseases, parathyroid diseases, celiac disease, vitiligo, gastritis, skin diseases, and rheumatic diseases. It is a consistent observation in clinics that T1DM patients have other autoimmune disorders which in turn affect their prognosis. Concomitant autoimmune illness might affect diabetes care and manifest itself clinically in a variety of ways. A thorough understanding of the complex pathogenesis of this modern-day epidemic and its association with other autoimmune disorders has been attempted in this review in order to delineate the measures to prevent the development of these conditions and limit the morbidity of the afflicted individuals as well. The measures including antibody screening in susceptible individuals, early identification and management of other autoimmune disorders, and adoption of personalized medicine can significantly enhance the quality of life of these patients. Personalized medicine has recently gained favor in the scientific, medical, and public domains, and is frequently heralded as the future paradigm of healthcare delivery. With the evolution of the 'omics', the individualization of therapy is not only closer to reality but also the need of the hour.

Metabolic stress-induced human beta-cell death is mediated by increased intracellular levels of adenosine.

High intracellular concentrations of adenosine and 2'-deoxyadenosine have been suggested to be an important mediator of cell death. The aim of the present study was to characterize adenosine-induced death in insulin-producing beta-cells, at control and high glucose + palmitate-induced stress conditions. Human insulin-producing EndoC-betaH1 cells were treated with adenosine, 2'-deoxyadenosine, inosine and high glucose + sodium palmitate, and death rates using flow cytometry were studied. We observed that adenosine and the non-receptor-activating analogue 2-deoxyadenosine, but not the adenosine deamination product inosine, promoted beta-cell apoptosis at concentrations exceeding maximal adenosine-receptor stimulating concentrations. Both adenosine and inosine were efficiently taken up by EndoC-betaH1 cells, and inosine counteracted the cell death promoting effect of adenosine by competing with adenosine for uptake. Both adenosine and 2'-deoxyadenosine promptly reduced insulin-stimulated production of plasma membrane PI(3,4,5)P3, an effect that was reversed upon wash out of adenosine. In line with this, adenosine, but not inosine, rapidly diminished Akt phosphorylation. Both pharmacological Bax inhibition and Akt activation blocked adenosine-induced beta-cell apoptosis, indicating that adenosine/2'-deoxyadenosine inhibits the PI3K/Akt/BAD anti-apoptotic pathway. High glucose + palmitate-induced cell death was paralleled by increased intracellular adenosine and inosine levels. Overexpression of adenosine deaminase-1 (ADA1) in EndoC-betaH1 cells, which increased Akt phosphorylation, prevented both adenosine-induced apoptosis and high glucose + palmitate-induced necrosis. ADA2 overexpression not only failed to protect against adenosine and high glucose + palmitate-activated cell death, but instead potentiated the apoptosis-stimulating effect of adenosine. In line with this, ADA1 overexpression increased inosine production from adenosine-exposed cells, whereas ADA2 did not. Knockdown of ADA1 resulted in increased cell death rates in response to both adenosine and high glucose + palmitate. Inhibition of miR-30e-3p binding to the ADA1 mRNA 3'-UTR promoted the opposite effects on cell death rates and reduced intracellular adenosine contents. It is concluded that intracellular adenosine/2'-deoxyadenosine regulates negatively the PI3K pathway and is therefore an important mediator of beta-cell apoptosis. Adenosine levels are controlled, at least in part, by ADA1, and strategies to upregulate ADA1 activity, during conditions of metabolic stress, could be useful in attempts to preserve beta-cell mass in diabetes.