Autoimmune Destruction Of Β-cells Research Articles

The immunology of type 1 diabetes.

Following the seminal discovery of insulin a century ago, treatment of individuals with type 1 diabetes (T1D) has been largely restricted to efforts to monitor and treat metabolic glucose dysregulation. The recent regulatory approval of the first immunotherapy that targets T cells as a means to delay the autoimmune destruction of pancreatic β-cells highlights the critical role of the immune system in disease pathogenesis and tends to pave the way for other immune-targeted interventions for T1D. Improving the efficacy of such interventions across the natural history of the disease will probably require a more detailed understanding of the immunobiology of T1D, as well as technologies to monitor residual β-cell mass and function. Here we provide an overview of the immune mechanisms that underpin the pathogenesis of T1D, with a particular emphasis on T cells.

Vascular Aging and Telomere Biology: The Role of Vitamin D3 Deficiency

Rationale. The impact of vitamin D3 deficiency on the risk and prognosis of numerous chronic diseases has been actively studied for years. Recent research has demonstrated that vitamin D is not merely involved in the control of calcium-phosphorus metabolism, but can also enhance insulin sensitivity, decrease the incidence of type 2 diabetes mellitus (T2DM), obesity and autoimmune destruction of pancreatic β-cells. The influence of vitamin D3 on some cardiometabolic risk factors and cardiovascular disease (CVD) was described. Thus studying the role of vitamin D3 in the development of arteries wall changes in T2DM and IR, and their relationship with biology telomere seems to be quite relevant.Aim. To study the relationship between vitamin D3 deficiency and vascular wall condition, telomere biology in patients with varying insulin sensitivity.Materials and methods. The cross-sectional study involved 305 patients (106 men and 199 women) aged 51.5 ± 13.3 y.o. All patients underwent laboratory and instrumental research methods, study of morphofunctional state vascular wall. Telomere length and telomerase activity were determined using polymerase chain reaction.Results. Totally, 18 patients out of 248 (7.2%) were found to have normal vitamin D3 level (more than 30 ng/ml). In 92.8% of those studied Vitamin D3 insufficiency or deficiency was determined. As increase in vitamin D3 deficiency, an increase in fasting glucose was noted, HbA1c and its elevated concentration, HOMA index, glucose disorders up to T2DM, higher vascular stiffness. Telomerase activity in group with vitamin D3 deficiency was significantly lower than in groups with vitamin D3 insufficiency and normal content. Multiple linear regression analysis revealed that they are independently associated with vitamin D3 in T2DM (B=1.43; st. OR. 0.106; p=0.0001), vascular stiffness (B=0.075; st. OR. 2.11; p=0.017), fasting glucose (B=0.169; st. OR 1.62; p=0.004), HbA1c level (B=0.062; st. OR. 7.4; p=0.001) and the presence of “short” telomeres (B=0.09; st. OR. 1.154; p=0.001). ROC analysis revealed relationships between BMI (0.634, p=0.001), duration of T2DM (0.651, p=0.022), high intima media thickness (0.614, p=0.004), vascular stiffness (0.605, p<0.001), HbA1c (0.588, p=0.022) and presence of vitamin D3 deficiency.Conclusion. In persons with varying insulin sensitivity — from insulin resistance up T2DM is advisable assess vitamin D3 levels for effective prevention of arterial wall changes in addition to traditional CVD risk factors. Availability Vitamin D3 deficiency requires active prevention metabolic disorders and vascular changes.

SAT069 Targeting Human β-Cell G Protein-coupled Receptors To Alter Cytokine-mediated Caspase Activation

Abstract Disclosure: K. Rodrigues dos Santos: None. N. Mukherjee: None. L.F. Barella: None. F. Armoo: None. D.L. Eizirik: None. A.T. Templin: None. M.A. Kalwat: None. In type 1 diabetes (T1D) autoimmune destruction of pancreatic islet β-cells causes a lack of insulin, leading to hyperglycemia. The development of therapies that can prevent β-cell death is critical. β-cell proliferation and survival pathways are affected by signaling through G protein-coupled receptors (GPCRs). Using high-depth RNA-seq, we found altered expression of 123 different GPCRs in human islets exposed to cytokines (IL1β 50U/ml + IFNγ 1000U/ml, 48 h) to model the T1D milieu. We hypothesized these candidates may be exploited for β-cell protection. Among the candidates, adenosine receptors (ADORA1 and ADORA2A), calcium-sensing receptor (CASR), and metabotropic glutamate receptor 4 (GRM4) stood out. Cytokines decreased the expression of ADORA1 and CASR, but increased ADORA2A and GRM4. To gauge the impact of agonizing/antagonizing these receptors, we pre-treated human EndoC-β H1 β-cells or islets with receptor ligands and co-treated with cytokines (IL1β 50U/ml + IFNγ or IL1β + 1000U/ml IFNγ + 1000U/ml TNFɑ, 48 h) and measured glucose-stimulated insulin secretion, cell viability, and gene expression. Each cytokine combination induced target gene expression (e.g. CXCL10), but only the combination of IL1β + IFNγ + TNFɑ reduced glucose-stimulated insulin secretion. Preliminary experiments indicated that adenosine receptor ligands had little impact in our assays. However, ligands for CASR and GRM4 exhibited significant suppression of cytokine-induced caspase 3/7 activation in EndoC-βH1 cells. Interestingly, suppressed caspase activation did not result in observable impacts on live/dead cell ratios or live-cell analysis using Incucyte in EndoC-βH1 cells. Consistently, we also observed cytokine-mediated cell death in the presence of the pan-caspase inhibitor ZVAD-fmk. We conclude that a variety of β-cell GPCR-mediated signaling pathways may converge to prevent cytokine-induced caspase activation, but additional measures are needed to enable protection from eventual cell death. Our results and this line of investigation is significant because understanding mechanisms of GPCR-cytokine crosstalk in β-cells will inform strategies to protect islets in other models of T1D. Funding: JDRF 1-INO-2022-1113-A-N and Diabetes Research Connection #33. Presentation: Saturday, June 17, 2023

Dietary Factors Associated with Glycemic Control in Children and Adolescents with Type 1 Diabetes.

Type 1 diabetes mellitus (T1DM) is a chronic metabolic disease that results from the autoimmune destruction of pancreatic β-cells, leading to insulin deficiency and hyperglycemia. It is a common chronic disease in childhood, with a prevalence of 1 in 300 children in the United States and an increasing incidence of 2-5% annually, worldwide. Managing T1DM requires regular insulin administration, adjustment of food intake and exercise, and a comprehensive understanding of nutrition. This review aims to explore the relationship between dietary factors, physical activity, obesity, genetics, and glycemic control in children and adolescents with T1DM. To conduct this review, we conducted a thorough search of publications from December 2004 through April 2022 using PubMed, ScienceDirect, and Embase databases. Key topics included obesity, children, adolescents, nutrients, carbohydrates, proteins, fat, water-soluble vitamins, fat-soluble vitamins, dietary patterns, fruits and vegetables, physical activity, genetics, food habits, carbohydrate count and environmental factors.

The use of stem cells and 3D bioprinting of pancreatic islets in the treatment of type 1 diabetes mellitus: history and perspectives

Type 1 diabetes mellitus (DM) is a disease characterized by hyperglycemia due to an absolute insulin deficiency caused by autoimmune destruction of insulin-producing β-cells. The disease occurs at a young age, is characterized by a labile course, a tendency to ketoacidosis and leads to the development of vascular complications that contribute to disability and early death of patients. To date, insulin therapy is the only treatment for type 1 diabetes. However, this method of treatment is not perfect. Patients need to adjust their diet, conduct frequent glycemic control and multiple injections of insulin. In this regard, the search for more effective methods of treating type 1 diabetes continues. The transformation of stem cells as a potential source of αand β-cells and their transplantation to the patient seems promising. However, it is not enough to simply obtain α- and β-cells from any stem cell. An important role is played by the interaction between the cells of the pancreatic islets. Currently, attempts are being made to develop functional in vitro models of pancreatic islets in which the cellular microenvironment would be completely preserved. The possibility of culturing and monitoring cells in a permeable three-dimensional microenvironment has been demonstrated. Combining different types of cells with each other in biologically suitable protein hydrogels allows the formation of spatial tissue systems. Cell microvascularization is also important, which is critical for adequate glucose homeostasis. 3D bioprinting can help ensure proper cell distribution in the scaffold and help reduce hypoxia through vascularization. 3D bioprinting technology will solve the problems of creating a natural environment for pancreatic islets with extracellular matrix and vasculature, since this technology will help to create organs in fully controlled conditions in vitro. However, this technology is still developing and further research is required in this direction.

Type 1 diabetes and microscopic colitis: A nationwide matched case-control study in Sweden.

Microscopic colitis (MC) is a colonic inflammatory condition associated with autoimmune dysfunction. Type 1 diabetes (T1D) is a chronic disease induced by autoimmune destruction of pancreatic β-cells. We aimed to examine the association between T1D and MC. A matched case-control study was conducted using the nationwide ESPRESSO cohort as study base. All biopsy-confirmed MC patients born after 1940 were identified and compared to biopsy-free individuals matched from the general population for T1D diagnosis using the Swedish National Patient Register. The T1D-MC association was estimated as odds ratios (ORs) and 95% confidence intervals (CIs) by conditional logistic models, considering differences by sex and MC subtype. Full sibling comparison and adjustment for MC-associated medications were also performed. We identified 352 (3.7%) and 945 (2.0%) T1D diagnoses from 9,600 MC cases and 47,870 matched population controls, respectively, which corresponded to an overall OR of 1.79 (95% CI: 1.56-2.05). The association was stronger for collagenous colitis (OR, 2.15; 95% CI: 1.70-2.71) than lymphocytic colitis (OR, 1.62; 95% CI: 1.37-1.92) and remained statistically significant in full sibling comparison (OR, 1.46; 95%: 1.18-1.81). Medication adjustment attenuated the association to null among females (OR: 1.02; 95% CI: 0.82-1.27) but not among males (OR: 1.45; 95% CI: 1.11-1.90). T1D diagnosis was almost 80% more prevalent in MC patients compared to general population. This positive association did not seem to be spurious due to residual confounding shared by full siblings but may relate to consumption of medications associated with MC onset.

S-17-2: CLUSTER ANALYSIS OF DIABETES AND HYPERTENSION

Diabetes mellitus is classified into type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) according to etiology. T1DM occurs due to autoimmune β-cell destruction, usually leading to absolute insulin deficiency, whereas T2DM occurs due to a heterogenous combination of a relative insulin deficiency and insulin resistance. A data-driven cluster analysis reported five exclusive subgroups for diabetes: cluster 1 (severe autoimmune diabetes [SAID]), cluster 2 (severe insulin-deficient diabetes [SIDD]), cluster 3 (severe insulin-resistant diabetes [SIRD]), cluster 4 (mild obesity-related diabetes [MOD]), and cluster 5 (mild age-related diabetes [MARD]) (Ahlqvist et al, 2018). The subgroups have an advantage over the other classification because it uses simple but pathophysiologically feasible factors and is proven to apply to ethnic and racial differences to estimate diabetic complications (Diabetes Res Clin Pract 2021:180;109067). The SIRD cluster shows obesity and moderate to severe insulin resistance with hyperinsulinemia. Under severe metabolic deterioration based on insulin resistance through ectopic fat accumulation, individuals with SIRD are at high risk of developing atherosclerotic cardiovascular disease (ASCVD). SIRD confers the highest risk of developing diabetic kidney disease (DKD), commonly in Caucasians [Ahlqvist et al., 2018)] and non-Caucasians [Tanabe, 2020]. I will discuss the possible connection between cluster-derived diabetes subgroups and hypertension-associated complications.

The role of specific pancreatic antibodies in the differential diagnosis of complete clinical and laboratory remission of type 1 diabetes mellitus and MODY in children

BACKGROUND: T1D is characterized by autoimmune destruction of pancreatic β-cells, which develops due to genetic and environmental risk factors. Shortly after initiating the treatment with insulin, 80% of children with T1D may require smaller doses of insulin and develop clinical and laboratory remission of the disease so called «honeymoon». The issue of whether there is a need of differential diagnosis between autoimmune DM and non-immune forms of DM raises in cases of preclinical diagnosis of T1D and laboratory remission for more than 6 months.AIM: To study the clinical, immunological, genetic characteristics of T1D remission phase and MODY in children, to determine the diagnostic criteria for T1D and MODY in children.MATERIALS AND METHODS: A single-centre, cross sectional noncontrolled comparative study of two independent cohorts. Data of 150 children examined in the Endocrinology Research Center (January 2016–June 2021). First cohort included patients with complete clinical and laboratory remission of T1D (n=36), second cohort included patients with MODY, confirmed by genetic study (n=114).RESULTS: The median age of diabetes manifestation was significantly higher in patients with T1D — 11.25 years [8.33; 13.78] than in patients with MODY — 7.5 years [4.6; 12.2] (p=0.004). In patients with T1D remission the level of glycated hemoglobin was 6.0% [5.6; 6.4], in group with MODY — 6.5% [6.2; 6.7] (p<0.001). Patients with monogenic diabetes had impaired fasting glucose — 6.27 mmol/l [5.38; 6.72], while patients with remission phase had normoglycemia — 5.12 mmol/l [4.17; 5.87]. The oral glucose tolerance test was perform to all patients, two-hour glucose level did not significantly differ in two groups (p=0.08). A strong family history of diabetes in patients with MODY registered more often (93% vs. 66.7%). A positive autoantibody titer detected more often in patients with remission of T1D (77.8%) than in patients with MODY (11.4%). In addition, no more than 1 type of autoantibodies was detected in patients with MODY.CONCLUSION: Antibodies ZnT8 and IA2 showed the greatest significance for the differential diagnosis of T1D and MODY in cases with long absents of insulin requirement in children with diabetes mellitus. Genetic test is recommended in seronegative cases. If only one type of AT is detected, specialist should decide on the need to do diagnostic genetic test based on a comprehensive analysis of the patient’s clinic characteristics, including family history, manifestation and blood glucose levels.

Acute presentation of immunotherapy-related diabetes mellitus without ketoacidosis, low C-peptide or elevated HbA1c.

The rapid rise in the use of immune checkpoint inhibitors as systemic cancer therapy has seen the emergence of immunotherapy-induced diabetes, a severe irreversible immunotherapy-related adverse event. Affected patients typically present with diabetic ketoacidosis (DKA) and low C-peptide consistent with insulin deficiency secondary to autoimmune β-cell destruction. We present the unusual case of a 61-year-old female with metastatic ampullary duodenal adenocarcinoma with primary tumour adjacent to the pancreatic head. She was commenced on immunotherapy after conventional systemic chemotherapy. Acute-onset hyperglycaemia was detected after 7 weeks on weekly blood glucose monitoring, with no glucocorticoid use or prior history of diabetes. On presentation, there was no evidence of DKA, and her glycated haemoglobin level was within the normal non-diabetic range at 5.3%, reflecting the acuity of her presentation. Initial serum C-peptide was preserved; however, it became undetectable a few weeks later, confirming insulin deficiency. We describe a case of atypical presentation of immunotherapy-induced diabetes, review the existing literature on this emerging clinical entity and discuss the differential diagnosis for new-onset diabetes mellitus in patients with metastatic cancer. Regular proactive glycaemic monitoring in patients receiving immunotherapy, particularly antibodies against programmed death ligand 1 and PD1, can facilitate very early detection of immunotherapy-induced diabetes, prompting insulin commencement and avoiding life-threatening presentations of diabetic ketoacidosis. Glycated haemoglobin can be within the normal range in patients diagnosed acutely with immunotherapy-induced diabetes. Serum C-peptide can be preserved initially in patients diagnosed with immunotherapy-induced diabetes but is likely to become undetectable during their illness. New-onset diabetes in patients with metastatic cancer carries a broad differential diagnosis.

Cathepsin D Drives the Formation of Hybrid Insulin Peptides Relevant to the Pathogenesis of Type 1 Diabetes.

Hybrid insulin peptides (HIPs) form in pancreatic β-cells through the formation of peptide bonds between proinsulin fragments and other peptides. HIPs have been identified in pancreatic islets by mass spectrometry and are targeted by CD4 T cells in patients with type 1 diabetes (T1D) as well as by pathogenic CD4 T-cell clones in nonobese diabetic (NOD) mice. The mechanism of HIP formation is currently poorly understood; however, it is well established that proteases can drive the formation of new peptide bonds in a side reaction during peptide bond hydrolysis. Here, we used a proteomic strategy on enriched insulin granules and identified cathepsin D (CatD) as the primary protease driving the specific formation of HIPs targeted by disease-relevant CD4 T cells in T1D. We also established that NOD islets deficient in cathepsin L (CatL), another protease implicated in the formation of disease-relevant HIPs, contain elevated levels of HIPs, indicating a role for CatL in the proteolytic degradation of HIPs. In summary, our data suggest that CatD may be a therapeutic target in efforts to prevent or slow the autoimmune destruction of β-cells mediated by HIP-reactive CD4 T cells in T1D.

Identification of autophagy-related genes as potential biomarkers for type 1 diabetes mellitus.

BackgroundType 1 diabetes mellitus (T1DM) is a metabolic disease in which the autoimmune destruction of pancreatic islet β-cells occurs. This study sought to investigate the role of autophagy-related genes and immune cells in the development of T1DM.MethodsWe acquired the raw gene expression profiles of 302 T1DM and 422 normal control peripheral blood samples from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) were identified using the Limma package, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed. The Search Tool for the Retrieval of Interacting Genes/Proteins (https://string-db.org/) and Cytoscape autophagy genes were intersected with the DEGs for the immune cell analysis and the correlation analysis.ResultsA total of 568 DEGs were identified in the T1DM and normal samples, of which 301 were upregulated and 267 were downregulated. The results of the functional and pathway enrichment analyses showed that the DEGs were closely associated with autophagy and immunity. Member RAS oncogene family (RAB11A), protein tyrosine phosphatase non-receptor type 11, lamin A/C, heat shock protein70, heat shock protein family A member 4, cluster of differentiation 8A, caspase 3 (CASP3), exportin 1, proto-oncogene, non-receptor tyrosine kinase, SMAD family member 4, and sirtuin 1 (SIRT1) were located at the center of the protein-protein interaction network as the core genes. The peripheral blood T cells were more elevated in the T1DM subjects than the normal subjects. RAB11A, CASP3, and SIRT1 are autophagy-associated genes. RAB11A and CASP3 were positively correlated with most immune cells, while SIRT1 was negatively correlated with most immune cells.ConclusionsAutophagy-related genes (i.e., RAB11A, CASP3, and SIRT1) and immune cells (i.e., T and B cells) may play important regulatory roles in the development of T1DM. Our findings provide novel insights into and potential targets for T1DM prediction and treatment.

PTPN2 Regulates the Interferon Signaling and Endoplasmic Reticulum Stress Response in Pancreatic β-Cells in Autoimmune Diabetes.

Type 1 diabetes (T1D) results from autoimmune destruction of β-cells in the pancreas. Protein tyrosine phosphatases (PTPs) are candidate genes for T1D and play a key role in autoimmune disease development and β-cell dysfunction. Here, we assessed the global protein and individual PTP profiles in the pancreas from nonobese mice with early-onset diabetes (NOD) mice treated with an anti-CD3 monoclonal antibody and interleukin-1 receptor antagonist. The treatment reversed hyperglycemia, and we observed enhanced expression of PTPN2, a PTP family member and T1D candidate gene, and endoplasmic reticulum (ER) chaperones in the pancreatic islets. To address the functional role of PTPN2 in β-cells, we generated PTPN2-deficient human stem cell-derived β-like and EndoC-βH1 cells. Mechanistically, we demonstrated that PTPN2 inactivation in β-cells exacerbates type I and type II interferon signaling networks and the potential progression toward autoimmunity. Moreover, we established the capacity of PTPN2 to positively modulate the Ca2+-dependent unfolded protein response and ER stress outcome in β-cells. Adenovirus-induced overexpression of PTPN2 partially protected from ER stress-induced β-cell death. Our results postulate PTPN2 as a key protective factor in β-cells during inflammation and ER stress in autoimmune diabetes.

Safety of the use of gold nanoparticles conjugated with proinsulin peptide and administered by hollow microneedles as an immunotherapy in type 1 diabetes.

Antigen-specific immunotherapy is an immunomodulatory strategy for autoimmune diseases, such as type 1 diabetes, in which patients are treated with autoantigens to promote immune tolerance, stop autoimmune β-cell destruction and prevent permanent dependence on exogenous insulin. In this study, human proinsulin peptide C19-A3 (known for its positive safety profile) was conjugated to ultrasmall gold nanoparticles (GNPs), an attractive drug delivery platform due to the potential anti-inflammatory properties of gold. We hypothesised that microneedle intradermal delivery of C19-A3 GNP may improve peptide pharmacokinetics and induce tolerogenic immunomodulation and proceeded to evaluate its safety and feasibility in a first-in-human trial. Allowing for the limitation of the small number of participants, intradermal administration of C19-A3 GNP appears safe and well tolerated in participants with type 1 diabetes. The associated prolonged skin retention of C19-A3 GNP after intradermal administration offers a number of possibilities to enhance its tolerogenic potential, which should be explored in future studies

Evaluation of Gamma Amino Butyric Acid (GABA) and Glibenclamide Combination Therapy in Streptozotocin Induced Diabetes.

Type 1-diabetes (T1D) is characterized by autoimmune destruction of β-cells and loss of endogenous insulin. A lifelong dependency on exogenous supply of insulin presents a great challenge in the pharmacotherapy of T1D that elicits a quest for alternative therapies, which can protect β-cells and revive their insulinogenic functions. GABA (γ-aminobutyric acid) has immunoprotective and β-cell regenerative capabilities. Co-administration of an insulin secretagogue, such as glibenclamide (Glib), along with GABA may enhance the pancreatic insulin output in T1D. The present study evaluated the possible mechanism of GABA in the improvement of glucose tolerance and its effects in streptozotocin (STZ) induced T1D along with Glib. Wistar rats (180-220 g) were administered a single dose of STZ (55 mg/kg, i.p.). GABA (100 mg/kg, i.p.) and Glib (5 or 10 mg/kg, i.p.) alone or in combination were administered for 28 days. Body weight (b.w.), water consumption, fasting blood glucose (FBG), oral glucose tolerance, plasma lipids, insulin, and muscle GLUT-4 (glucose transporters) protein level were assessed. T1D significantly decreased b.w. and increased water-intake in rats. An increase in FBG and a decrease in plasma insulin and muscle GLUT-4 indicated STZ-triggered destruction of β-cells in diabetic rats accompanied with dyslipidemia. GABA or Glib (10 mg/kg) significantly improved b.w., plasma insulin and GLUT-4 levels, and ameliorated FBG and blood lipid profile in diabetic rats. GABA and Glib (5 mg/kg) combination therapy achieved far better control over hyperglycemia and related pathogenic conditions (b.w., water-intake, insulin, GLUT-4, lipids). The anti-diabetic effect of combination therapy was significantly more pronounced in comparison to individual drug treatments. Histopathological analysis revealed an increase in the number of functional pancreatic-islets by combination therapy. GABA revitalized β-cells against STZ-toxicity. GABA and Glib synergistically augmented insulin secretion that can be used to manage T1D and its complications. GABA has the potential to remarkably enhance the therapeutic outcome in diabetic patients and reduce the dose of existing anti-diabetic drugs such as Glib.

CD8+ T Cells Variably Recognize Native Versus Citrullinated GRP78 Epitopes in Type 1 Diabetes.

In type 1 diabetes, autoimmune β-cell destruction may be favored by neoantigens harboring posttranslational modifications (PTMs) such as citrullination. We studied the recognition of native and citrullinated glucose-regulated protein (GRP)78 peptides by CD8+ T cells. Citrullination modulated T-cell recognition and, to a lesser extent, HLA-A2 binding. GRP78-reactive CD8+ T cells circulated at similar frequencies in healthy donors and donors with type 1 diabetes and preferentially recognized either native or citrullinated versions, without cross-reactivity. Rather, the preference for native GRP78 epitopes was associated with CD8+ T cells cross-reactive with bacterial mimotopes. In the pancreas, a dominant GRP78 peptide was instead preferentially recognized when citrullinated. To further clarify these recognition patterns, we considered the possibility of citrullination in the thymus. Citrullinating peptidylarginine deiminase (Padi) enzymes were expressed in murine and human medullary epithelial cells (mTECs), with citrullinated proteins detected in murine mTECs. However, Padi2 and Padi4 expression was diminished in mature mTECs from NOD mice versus C57BL/6 mice. We conclude that, on one hand, the CD8+ T cell preference for native GRP78 peptides may be shaped by cross-reactivity with bacterial mimotopes. On the other hand, PTMs may not invariably favor loss of tolerance because thymic citrullination, although impaired in NOD mice, may drive deletion of citrulline-reactive T cells.

Type 1 Diabetes and Associated Cardiovascular Damage: Contribution of Extracellular Vesicles in Tissue Crosstalk.

Significance: Type 1 diabetes (T1D) is characterized by the autoimmune destruction of the insulin secreting β-cells, with consequent aberrant blood glucose levels. Hyperglycemia is the common denominator for most of the chronic diabetic vascular complications, which represent the main cause of life reduction in T1D patients. For this disease, three interlaced medical needs remain: understanding the underlying mechanisms involved in pancreatic β-cell loss; identifying biomarkers able to predict T1D progression and its related complications; recognizing novel therapeutic targets. Recent Advances: Extracellular vesicles (EVs), released by most cell types, were discovered to contain a plethora of different molecules (including microRNAs) with regulatory properties, which are emerging as mediators of cell-to-cell communication at the paracrine and endocrine level. Recent knowledge suggests that EVs may act as pathogenic factors, and be developed into disease biomarkers and therapeutic targets in the context of several human diseases. Critical Issues: EVs have been recently shown to sustain a dysregulated cellular crosstalk able to exacerbate the autoimmune response in the pancreatic islets of T1D; moreover, EVs were shown to be able to monitor and/or predict the progression of T1D and the insurgence of vasculopathies. Future Directions: More mechanistic studies are needed to investigate whether the dysregulation of EVs in T1D patients is solely reflecting the progression of diabetes and related complications, or EVs also directly participate in the disease process, thus pointing to a potential use of EVs as therapeutic targets/tools in T1D. Antioxid. Redox Signal. 36, 631-651.

Engineering islets from stem cells for advanced therapies of diabetes.

Diabetes mellitus is a metabolic disorder that affects more than 460 million people worldwide. Type 1 diabetes (T1D) is caused by autoimmune destruction of β-cells, whereas type 2 diabetes (T2D) is caused by a hostile metabolic environment that leads to β-cell exhaustion and dysfunction. Currently, first-line medications treat the symptomatic insulin resistance and hyperglycaemia, but do not prevent the progressive decline of β-cell mass and function. Thus, advanced therapies need to be developed that either protect or regenerate endogenous β-cell mass early in disease progression or replace lost β-cells with stem cell-derived β-like cells or engineered islet-like clusters. In this Review, we discuss the state of the art of stem cell differentiation and islet engineering, reflect on current and future challenges in the area and highlight the potential for cell replacement therapies, disease modelling and drug development using these cells. These efforts in stem cell and regenerative medicine will lay the foundations for future biomedical breakthroughs and potentially curative treatments for diabetes.

Hemocompatible L-Type amino acid transporter 1 (LAT1)-Utilizing prodrugs of perforin inhibitors can accumulate into the pancreas and alleviate inflammation-induced apoptosis

Cytolytic pore-forming protein, perforin, has been associated with autoimmune destruction of pancreatic β-cells in type 1 diabetes mellitus (T1DM) once released from CD8+ T cells. Curiously, perforinopathy has also been implicated in numerous brain diseases. Therefore, inhibitors of perforin have been in demand with targeted delivery in mind. l-Type amino acid transporter 1 (LAT1) is known to be expressed in both the above-mentioned target tissues, in the pancreas as well as in the brain. Thus, in the present study, the distribution of two LAT1-utilizing prodrugs of investigational perforin inhibitors into the pancreas was explored after intraperitoneal (i.p., 30 μmol/kg) bolus injection to mice. The effects of prodrug 1 were also studied in lipopolysaccharide (LPS)-induced in vitro (50 μg/mL) and in vivo (250 μg/kg x 3 days) apoptosis and pancreatitis models by determining the cellular apoptotic levels with human umbilical vein endothelial cells (HUVEC) and pancreatic caspase-3/-7 activity in mice. Furthermore, the biocompatibility of prodrug 1 was explored in human plasma and towards red blood cells. According to the results, both prodrugs were accumulated more effectively into the pancreas than their parent drugs (in addition to the brain that has been previously reported). Prodrug 1 (30 μmol/kg) also decreased the pancreatic caspase-3/-7 activity (52%) and with 2.5 μM concentration, the number of early and late apoptotic cells (32–53%). Since prodrug 1 was also found to be hemocompatible and not affecting human plasma hemostasis or inducing hemolysis of erythrocytes at the concentration <50 μM, it can be considered biocompatible in systemic circulation and ready to be studied in the future as a dual-acting drug candidate (in the pancreas and brain) in diseases like T1DM with neurodegenerative comorbidities.

Novel autoantibodies to the β-cell surface epitopes of ZnT8 in patients progressing to type-1 diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by autoimmune destruction of insulin-producing β-cells in pancreatic islets. Seroconversions to islet autoantibodies (IAbs) precede the disease onset by many years, but the role of humoral autoimmunity in the disease initiation and progression are unclear. In the present study, we identified a new IAb directed to the extracellular epitopes of ZnT8 (ZnT8ec) in newly diagnosed patients with T1D, and demonstrated immunofluorescence staining of the surface of human β-cells by autoantibodies to ZnT8ec (ZnT8ecA). With the assay specificity set on 99th percentile of 336 healthy controls, the ZnT8ecA positivity rate was 23.6% (74/313) in patients with T1D. Moreover, 30 children in a longitudinal follow up of clinical T1D development were selected for sequential expression of four major IAbs (IAA, GADA, IA-2A and ZnT8icA). Among them, 10 children were ZnT8ecA positive. Remarkably, ZnT8ecA was the earliest IAb to appear in all 10 children. The identification of ZnT8ec as a cell surface target of humoral autoimmunity in the earliest phase of IAb responses opens a new avenue of investigation into the role of IAbs in the development of β-cell autoimmunity.

1127-P: Expression-Based Genome-Wide Association Study Links Osteopontin and Interleukin-1 Receptor Antagonist with Type 1 Diabetes

Type 1 diabetes (T1D) is caused by autoimmune destruction of insulin-producing β-cells in the pancreatic islets. Islet autoantibodies (IAbs) are indicators of islet autoimmunity. However, IAbs do not fully meet the need for the prediction of future hyperglycemia and the rate of disease progression. We assumed that functional proteins associated with autoimmune cellular process are great sources for biomarkers. In an attempt to identify additional biomarkers, we performed an expression-based genome-wide association study (eGWAS) using microarray data from 169 arrays of the pancreatic islets of T1D rodents. We ranked all 16,099 protein-coding genes by the likelihood of finding repeated differential expression in the pancreatic islets. Our top 20 secreted proteins were screened using the serum samples from newly diagnosed children with diabetes. First, we screened 20 selected candidates with 170 sera including 100 T1D, and 50 type 2 diabetes (T2D) and 20 age matched healthy children. With 7 proteins showing significance, we further did validation study using the second set of 400 samples from newly diagnosed children with diabetes and age matched controls including 200 T1D, 100 T2D, and 100 age-matched controls. We identified 2 serum proteins were significantly changed in T1D vs. both control and T2D and 5 serum proteins were significantly changed in both T1D and T2D vs. control. Serum Osteopontin (OPN) levels were uniquely higher in T1D (p&amp;lt; 0.0001) with no difference between T2D and healthy control subjects. Serum Interleukin 1 receptor antagonist (IL-1RA) levels were lower in T1D compared with both T2D (p&amp;lt;0.001) and healthy subjects (p&amp;lt; 0.0001). Our results suggest that OPN and IL1RA could be the useful biomarkers of T1D in children. Disclosure X. Jia: None. K. Toda: None. L. He: None. D. Miao: None. S. Yamada: None. L. Yu: None. K. Kodama: None. Funding JDRF (2-SRA-2019-695-S-B)