Development Of Autoimmune Diabetes Research Articles

CXCL16-dependent scavenging of oxidized lipids by islet macrophages promotes differentiation of pathogenic CD8+ T cells in diabetic autoimmunity

The pancreatic islet microenvironment is highly oxidative, rendering β cells vulnerable to autoinflammatory insults. Here, we examined the role of islet resident macrophages in the autoimmune attack that initiates type 1 diabetes. Islet macrophages highly expressed CXCL16, a chemokine and scavenger receptor for oxidized low-density lipoproteins (OxLDLs), regardless of autoimmune predisposition. Deletion of Cxcl16 in nonobese diabetic (NOD) mice suppressed the development of autoimmune diabetes. Mechanistically, Cxcl16 deficiency impaired clearance of OxLDL by islet macrophages, leading to OxLDL accumulation in pancreatic islets and a substantial reduction in intra-islet transitory (Texint) CD8+ Tcells displaying proliferative and effector signatures. Texint cells were vulnerable to oxidative stress and diminished by ferroptosis; PD-1 blockade rescued this population and reversed diabetes resistance in NOD.Cxcl16-/- mice. Thus, OxLDL scavenging in pancreatic islets inadvertently promotes differentiation of pathogenic CD8+ Tcells, presenting a paradigm wherein tissue homeostasis processes can facilitate autoimmune pathogenesis in predisposed individuals.

Myo9b mutations are associated with altered dendritic cell functions and increased susceptibility to autoimmune diabetes onset

The regulation of autoimmunity against pancreatic islet β cells for type 1 diabetes (T1D) onset is still unclear. NOD/ShiLtJ (NOD) mice are prone to the onset of autoimmune diabetes, but its congenic strain, ALR/Lt (ALR), is not. Here we show that dendritic cells (DC) in ALR mice have impaired migratory and T-cell priming capability. Genomic comparative analysis maps a 33-bp deletion in the ALR Myosin IXb (Myo9b) gene when compared with NOD genome; meanwhile, data from knock-in models show that this ALR Myo9b allele impairs phenotypic and functional maturation of DCs, and prevents the development and progression of spontaneous autoimmune diabetes in NOD mice. In parallel, while the ALR 33-bp deletion of Myo9b is not conserved in human, we find a MYO9B R133Q polymorphism associating with increased risk of T1D and enhanced DC function in patients with T1D. Our results thus hint that alterations in Myo9b may contribute to altered DC function and autoimmune diabetes onset.

Novel engineered B lymphocytes targeting islet-specific T cells inhibit the development of type 1 diabetes in non-obese diabetic Scid mice.

In this study, we report a novel therapeutic approach using B lymphocytes to attract islet-specific T cells in the non-obese diabetic (NOD) mouse model and prevent the development of autoimmune diabetes. Rather than using the antibody receptor of B cells, this approach utilizes their properties as antigen-presenting cells to T cells. Purified splenic B cells were treated with lipopolysaccharide, which increases regulatory B (Breg) cell function, then electroporated with mRNA encoding either chimeric MHC-I or MHC-II molecules covalently linked to antigenic peptides. Immunoregulatory functions of these engineered B cells (e-B cells) were tested by in vitro assays and in vivo co-transfer experiments with beta-cell-antigen-specific CD8+ or CD4+ T cells in NOD.Scid mice, respectively. The e-B cells expressing chimeric MHC-I-peptide inhibited antigen-specific CD8+ T-cell cytotoxicity in vitro. The e-B cells expressing chimeric MHC-II-peptide induced antigen-specific CD4+ T cells to express the regulatory markers, PD-1, ICOS, CTLA-4, Lag3, and Nrp1. Furthermore, e-B cells encoding the chimeric MHC-I and MHC-II peptide constructs protected NOD.Scid mice from autoimmune diabetes induced by transfer of antigen-specific CD8+ and CD4+ T cells. MHC-peptide chimeric e-B cells interacted with pathogenic T cells, and protected the host from autoimmune diabetes, in a mouse model. Thus, we have successfully expressed MHC-peptide constructs in B cells that selectively targeted antigen-specific cells, raising the possibility that this strategy could be used to endow different protective cell types to specifically regulate/remove pathogenic cells.

The role of cholecalciferol deficiency in the development of latent autoimmune diabetes in adults

Background. Recently, a lot of information has appeared on the role of cholecalciferol deficiency in the development of the mechanisms of classical types of diabetes mellitus (DM) and its complications. However, there are currently almost no data regarding latent autoimmune diabetes in adults (LADA). The purpose of this study was to determine the effect of vitamin D deficiency on the compensation of carbohydrate metabolism in LADA. Materials and methods. The study included 56 patients with DM: 34 with LADA and 22 with classical type 1 DM (DM1), as well as 20 practically healthy individuals of the control group. According to the main phenotypes, patients with LADA were divided into 2 groups: LADA1 and LADA2. Cholecalciferol status was determined by the immunochemiluminescence method. Results. The fasting blood glucose level in LADA and DM1 group was significantly higher than in the controls, by 63.9 and 91.1 % (p < 0.001), respectively, and was also 16.6 % higher when comparing DM1/LADA groups (p < 0.05). The level of HbA1c in 66.1 % of patients of the experimental groups was more than 7 %, which indicates insufficient compensation of the disease. The content of vitamin D was significantly lower in the experimental groups compared to the controls; when comparing LADA/DM1 — by 43.7 % lower in case of classical DM1 (p < 0.05). Compensation of carbohydrate metabolism is worse in patients with LADA1 than in LADA2, and the lowest level of vitamin D was recorded in LADA1. According to the linear regression analysis of correlations in patients with LADA, negative correlations of medium strength were recorded between the level of cholecalciferol and fasting blood glucose (r = 0.487; p < 0.05), HbA1c (r = –0.593; p < 0.05); positive — between cholecalciferol and C-peptide (r = 0.412; p < 0.05). Conclusions. In patients with autoimmune diabetes, there is an insufficient supply of cholecalciferol. Low cholecalciferol content is observed in both groups of patients with LADA regardless of the disease phenotype and is associated with worse compensation of DM.

Antidiabetic and Immunoregulatory Activities of Extract of Phyllanthus emblica L. in NOD with Spontaneous and Cyclophosphamide-Accelerated Diabetic Mice.

Oil-Gan, also known as emblica, is the fruit of the genus Phyllanthus emblica L. The fruits are high in nutrients and display excellent health care functions and development values. The primary aim of this study was to investigate the activities of ethyl acetate extract from Phyllanthus emblica L. (EPE) on type 1 diabetes mellitus (T1D) and immunoregulatory activities in non-obese diabetes (NOD) mice with spontaneous and cyclophosphamide (Cyp)-accelerated diabetes. EPE was vehicle-administered to spontaneous NOD (S-NOD) mice or Cyp-accelerated NOD (Cyp-NOD) mice once daily at a dose of 400 mg/kg body weight for 15 or 4 weeks, respectively. At the end, blood samples were collected for biological analyses, organ tissues were dissected for analyses of histology and immunofluorescence (IF) staining (including expressions of Bcl and Bax), the expression levels of targeted genes by Western blotting and forkhead box P3 (Foxp3), and helper T lymphocyte 1 (Th1)/Th2/Th17/Treg regulatory T cell (Treg) cell distribution by flow cytometry. Our results showed that EPE-treated NOD mice or Cyp-accelerated NOD mice display a decrease in levels of blood glucose and HbA1c, but an increase in blood insulin levels. EPE treatment decreased blood levels of IFN-γ and tumor necrosis α (TNF-α) by Th1 cells, and reduced interleukin (IL)-1β and IL-6 by Th17 cells, but increased IL-4, IL-10, and transforming growth factor-β1 (TGF-β1) by Th2 cells in both of the two mice models by enzyme-linked immunosorbent assay (ELISA) analysis. Flow cytometric data showed that EPE-treated Cyp-NOD mice had decreased the CD4+ subsets T cell distribution of CD4+IL-17 and CD4+ interferon gamma (IFN-γ), but increased the CD4+ subsets T cell distribution of CD4+IL-4 and CD4+Foxp3. Furthermore, EPE-treated Cyp-NOD mice had decreased the percentage per 10,000 cells of CD4+IL-17 and CD4+IFNγ, and increased CD4+IL-4 and CD4+Foxp3 compared with the Cyp-NOD Con group (p < 0.001, p < 0.05, p < 0.05, and p < 0.05, respectively). For target gene expression levels in the pancreas, EPE-treated mice had reduced expression levels of inflammatory cytokines, including IFN-γ and TNF-α by Th1 cells, but increased expression levels of IL-4, IL-10, and TGF-1β by Th2 cells in both two mice models. Histological examination of the pancreas revealed that EPE-treated mice had not only increased pancreatic insulin-expressing β cells (brown), and but also enhanced the percentage of Bcl-2 (green)/Bax (red) by IF staining analyses of islets compared with the S-NOD Con and the Cyp-NOD Con mice, implying that EPE displayed the protective effects of pancreas β cells. EPE-treated mice showed an increase in the average immunoreactive system (IRS) score on insulin within the pancreas, and an enhancement in the numbers of the pancreatic islets. EPE displayed an improvement in the pancreas IRS scores and a decrease in proinflammatory cytokines. Moreover, EPE exerted blood-glucose-lowering effects by regulating IL-17 expressions. Collectively, these results implied that EPE inhibits the development of autoimmune diabetes by regulating cytokine expression. Our results demonstrated that EPE has a therapeutic potential in the preventive effects of T1D and immunoregulation as a supplementary.

NOD mouse dorsal root ganglia display morphological and gene expression defects before and during autoimmune diabetes development.

During the development of Autoimmune Diabetes (AD) an autoimmune attack against the Peripheral Nervous System occurs. To gain insight into this topic, analyses of Dorsal Root Ganglia (DRG) from Non-Obese Diabetic (NOD) mice were carried out. Histopathological analysis by electron and optical microscopy in DRG samples, and mRNA expression analyzes by the microarray technique in DRG and blood leukocyte samples from NOD and C57BL/6 mice were performed. The results showed the formation of cytoplasmic vacuoles in DRG cells early in life that could be related to a neurodegenerative process. In view of these results, mRNA expression analyses were conducted to determine the cause and/or the molecules involved in this suspected disorder. The results showed that DRG cells from NOD mice have alterations in the transcription of a wide range of genes, which explain the previously observed alterations. In addition, differences in the transcription genes in white blood cells were also detected. Taken together, these results indicate that functional defects are not only seen in beta cells but also in DRG in NOD mice. These results also indicate that these defects are not a consequence of the autoimmune process that takes place in NOD mice and suggest that they may be involved as triggers for its development.

Stem-Cell-Derived β-Like Cells with a Functional PTPN2 Knockout Display Increased Immunogenicity.

Type 1 diabetes is a polygenic disease that results in an autoimmune response directed against insulin-producing beta cells. PTPN2 is a known high-risk type 1 diabetes associated gene expressed in both immune- and pancreatic beta cells, but how genes affect the development of autoimmune diabetes is largely unknown. We employed CRISPR/Cas9 technology to generate a functional knockout of PTPN2 in human pluripotent stem cells (hPSC) followed by differentiating stem-cell-derived beta-like cells (sBC) and detailed phenotypical analyses. The differentiation efficiency of PTPN2 knockout (PTPN2 KO) sBC is comparable to wild-type (WT) control sBC. Global transcriptomics and protein assays revealed the increased expression of HLA Class I molecules in PTPN2 KO sBC at a steady state and upon exposure to proinflammatory culture conditions, indicating a potential for the increased immune recognition of human beta cells upon differential PTPN2 expression. sBC co-culture with autoreactive preproinsulin-reactive T cell transductants confirmed increased immune stimulations by PTPN2 KO sBC compared to WT sBC. Taken together, our results suggest that the dysregulation of PTPN2 expression in human beta cell may prime autoimmune T cell reactivity and thereby contribute to the development of type 1 diabetes.

PMON110 Panhypopituitarism as a Rare Presentation of Erdheim – Chester disease (ECD) in an Adolescent Patient

Abstract Background Erdheim-Chester disease (ECD) is a rare multisystemic histiocytic disorder. Only a dozen pediatric cases are reported. Here, we present a case of ECD in a pediatric patient who presented with short stature and delayed puberty. Clinical Case A 14-year-old male with history of autism and ADHD presented with short stature and pubertal delay. He grew along the 40th percentile until age 7 years when growth velocity declined. On exam, his height was 145.6 cm (0.98%ile, z-score -2.34), weight was 55.6 kg (63.19%ile, z-score 0.34), and testicular size was 5-6 mL. He had increased thirst and episodes of bedwetting since age 7. Bone age was delayed at 11 years 6 months. Further workup was recommended, but family was lost to follow up. At 16, he returned with continued poor growth, polydipsia, and nocturia. Height was 153 cm (0.26%ile, z-score -2.80), weight 61.1 kg (40%ile, z-score -0.25). Labs revealed IGF-BP3 2.8mcg/mL(3.1-8.9), IGF-1 35ng/mL(245-522), LH 1.2mIU/mL(0.29-4.77), and total testosterone &amp;lt;7.0 ng/dL(250-1100). Prolactin, cortisol, thyroid, and karyotype were normal. Growth hormone (GH) stimulation test confirmed GH deficiency. He was referred to oncology clinic when a brain MRI revealed a nodular enhancing suprasellar mass extending from the third ventricular floor to the dorsum sella along the pituitary stalk and rounded sclerotic lesion in the frontal bone. Biopsy of the suprasellar lesion was remarkable for foamy histiocytes positive for CD68, negative for S100 and CD1a, an eosinophilic cell background highlighted by S100 and synaptophysin, SALL4 negative. A diagnosis of xanthomatous hypophysitis was made. Additionally, lab studies confirmed diabetes insipidus (DI), treated with DDAVP. Growth hormone was trialed for 2 weeks, but he developed acute pancreatitis, so it was discontinued. He subsequently developed recurrent pancreatitis of unclear etiology requiring frequent hospitalization with development of insulin-dependent diabetes mellitus due to pancreatic damage. He was lost to follow up for 12 months after leaving home at age 18. He returned to our institution after incidental findings of 7th right rib expansile lytic bony lesions on abdominal CT during a pancreatitis admission. Biopsy of the rib lesion was positive for a BRAF-V600E mutation. Skeletal survey revealed new multiple small lytic skull lesions. Repeat brain MRI demonstrated new calvarial lesions, increased suprasellar mass. Chest CT scan showed a micronodular pattern with mediastinal lymph node enlargement. PET confirmed widespread multifocal FDG hypermetabolic lesions. Final diagnosis of ECD was made; he was started on targeted therapy with Vemurafenib, a BRAF inhibitor. Conclusion Erdheim-Chester disease (ECD) is a non-Langerhans cell histiocytosis, which rarely affects pediatric patients who present with bone pain and DI; however, here we present a case of ECD in an adolescent with short stature and multiple pituitary deficiencies to highlight the varied presentation of the disorder. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Abstract 1358: The selective HDAC6 inhibitor ITF3756 stimulates an antitumor immune response and leads to tumor regression in combination with anti CTLA-4 antibody in a colon carcinoma murine model

Abstract Stimulation of tumor immune response with antibodies blocking the repressive activity of immune checkpoints gives impressive results with long-lasting tumor regression that is achieved regrettably only in a fraction of patients. To overcome these suboptimal results, different targets and combination therapies are the aim of active non-clinical and clinical research. Importantly, clinical trials of combination therapies have demonstrated better efficacy but also an increase of adverse events. HDAC6 is a member of the Zn-dependent histone deacetylase family of enzymes with peculiar structure and functions. In contrast to what is observed with many other HDAC family members, HDAC6 KO mice are viable and have no peculiar phenotype indicating that selective HDAC6 inhibitors should be well tolerated. Since HDAC6 is an obligate regulator of cytokine-induced PD-L1 expression, HDAC6 inhibitors might have a role in modulating tumor immune responses. We here report the in vivo efficacy of ITF3756, a potent and selective HDAC6 inhibitor that reduces in vitro the expression of PD-L1 on human monocytes and on CD8 T cells, counters immune exhaustion in CD8 T cells but shows no direct cytotoxic effects on a panel of murine tumor cell lines. In syngeneic tumor models ITF3756 showed anti-tumor activity that was comparable to the efficacy of an anti PD1 antibody and that went along with increased immune cell infiltration and the generation of tumor-reactive CD8 and CD4 cells. ITF3756 was inactive in immune-deficient animals and selective depletion of either CD8 or CD4 cells severely blunted the antitumor activity of ITF3756. In combination with an anti CTLA-4 antibody, ITF3756 lead to a complete tumor eradication in 50% of the animals. Re-challenge of these animals did not result in tumor growth indicating that the combination therapy had elicited tumor immunity. Blocking the PD-1/PD-L1 axis either alone or in combination with inhibition of CTLA4 in NOD mice strongly accelerated the development of auto-immune diabetes that was lethal in some treatment groups. In contrast neither ITF3756 alone nor the combination with anti CTLA4 lead to any significant induction of diabetes despite the activity of ITF3756 on the PD-1/PD-L1 axis. We conclude that ITF3756 induces an in vivo antitumor immune response and a durable antitumor activity when combined with an anti CTLA-4 antibody. Neither ITF3756 monotherapy nor the combination with anti CTLA4 accelerated the induction of autoimmune diabetes in NOD mice suggesting a favorable safety profile that was confirmed in preclinical GLP toxicology studies. Phase I clinical trials with ITF3756 will be initiated this year. Citation Format: Gianluca Fossati, Chiara Ripamonti, Gianluca Caprini, Pietro Pozzi, Elisabetta Galbiati, Paola Cordella, Mattia Marchini, Barbara Vergani, Giovanni Sandrone, Andrea Stevenazzi, Christian Steinkuhler. The selective HDAC6 inhibitor ITF3756 stimulates an antitumor immune response and leads to tumor regression in combination with anti CTLA-4 antibody in a colon carcinoma murine model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1358.

Interleukin-35 Prevents Development of Autoimmune Diabetes Possibly by Maintaining the Phenotype of Regulatory B Cells.

The anti-inflammatory role of regulatory B cells (Breg cells) has been associated with IL-35 based on studies of experimental autoimmune uveitis and encephalitis. The role of Breg cells and IL-35+ Breg cells for type 1 diabetes (T1D) remains to be investigated. We studied PBMCs from T1D subjects and healthy controls (HC) and found lowered proportions of Breg cells and IL-35+ Breg cells in T1D. To elucidate the role of Breg cells, the lymphoid organs of two mouse models of T1D were examined. Lower proportions of Breg cells and IL-35+ Breg cells were found in the animal models of T1D compared with control mice. In addition, the systemic administration of recombinant mouse IL-35 prevented hyperglycemia after multiple low dose streptozotocin (MLDSTZ) injections and increased the proportions of Breg cells and IL-35+ Breg cells. A higher proportion of IFN-γ+ cells among Breg cells were found in the PBMCs of the T1D subjects. In the MLDSTZ mice, IL-35 administration decreased the proportions of IFN-γ+ cells among the Breg cells. Our data illustrate that Breg cells may play an important role in the development of T1D and that IL-35 treatment prevents the development of hyperglycemia by maintaining the phenotype of the Breg cells under an experimental T1D condition.

Prenatal cadmium exposure does not induce greater incidence or earlier onset of autoimmunity in the offspring.

We previously demonstrated that exposure of adult mice to environmental levels of cadmium (Cd) alters immune cell development and function with increases in anti-streptococcal antibody levels, as well as decreases in splenic natural regulatory T cells (nTreg) in the adult female offspring. Based on these data, we hypothesized that prenatal Cd exposure could predispose an individual to developing autoimmunity as adults. To test this hypothesis, the effects of prenatal Cd on the development of autoimmune diabetes and arthritis were investigated. Non-obese diabetic (NOD) mice were exposed to Cd in a manner identical to our previous studies, and the onset of diabetes was assessed in the offspring. Our results showed a similar time-to-onset and severity of disease to historical data, and there were no statistical differences between Cd-exposed and control offspring. Numerous other immune parameters were measured and none of these parameters showed biologically-relevant differences between Cd-exposed and control animals. To test whether prenatal Cd-exposure affected development of autoimmune arthritis, we used SKG mice. While the levels of arthritis were similar between Cd-exposed and control offspring of both sexes, the pathology of arthritis determined by micro-computed tomography (μCT) between Cd-exposed and control animals, showed some statistically different values, especially in the female offspring. However, the differences were small and thus, the biological significance of these changes is open to speculation. Overall, based on the results from two autoimmune models, we conclude that prenatal exposure to Cd did not lead to a measurable propensity to develop autoimmune disease later in life.

High-fat diet prevents the development of autoimmune diabetes in NOD mice.

AimsType 1 diabetes (T1D) has a strong genetic predisposition and requires an environmental trigger to initiate the beta‐cell autoimmune destruction. The rate of childhood obesity has risen in parallel to the proportion of T1D, suggesting high‐fat diet (HFD)/obesity as potential environmental triggers for autoimmune diabetes. To explore this, non‐obese diabetic (NOD) mice were subjected to HFD and monitored for the development of diabetes, insulitis and beta‐cell stress.Materials and MethodsFour‐week‐old female NOD mice were placed on HFD (HFD‐NOD) or standard chow‐diet. Blood glucose was monitored weekly up to 40 weeks of age, and glucose‐ and insulin‐tolerance tests performed at 4, 10 and 15 weeks. Pancreata and islets were analysed for insulin secretion, beta‐cell mass, inflammation, insulitis and endoplasmic reticulum stress markers. Immune cell levels were measured in islets and spleens. Stool microbiome was analysed at age 4, 8 and 25 weeks.ResultsAt early ages, HFD‐NOD mice showed a significant increase in body weight, glucose intolerance and insulin resistance; but paradoxically, they were protected from developing diabetes. This was accompanied by increased insulin secretion and beta‐cell mass, decreased insulitis, increased splenic T‐regulatory cells and altered stool microbiome.ConclusionsThis study shows that HFD protects NOD mice from autoimmune diabetes and preserves beta‐cell mass and function through alterations in gut microbiome, increased T‐regulatory cells and decreased insulitis. Further studies into the exact mechanism of HFD‐mediated prevention of diabetes in NOD mice could potentially lead to interventions to prevent or delay T1D development in humans.

The role of vitamin D deficiency in the development of latent autoimmune diabetes in adults

The role of vitamin D deficiency in the development of latent autoimmune diabetes in adults

Fatty acid binding protein 4 promotes autoimmune diabetes by recruitment and activation of pancreatic islet macrophages.

Both innate and adaptive immune cells are critical players in autoimmune destruction of insulin-producing β cells in type 1 diabetes. However, the early pathogenic events triggering the recruitment and activation of innate immune cells in islets remain obscure. Here we show that circulating fatty acid binding protein 4 (FABP4) level was significantly elevated in patients with type 1 diabetes and their first-degree relatives and positively correlated with the titers of several islet autoantibodies. In nonobese diabetic (NOD) mice, increased FABP4 expression in islet macrophages started from the neonatal period, well before the occurrence of overt diabetes. Furthermore, the spontaneous development of autoimmune diabetes in NOD mice was markedly reduced by pharmacological inhibition or genetic ablation of FABP4 or adoptive transfer of FABP4-deficient bone marrow cells. Mechanistically, FABP4 activated innate immune responses in islets by enhancing the infiltration and polarization of macrophages to proinflammatory M1 subtype, thus creating an inflammatory milieu required for activation of diabetogenic CD8+ T cells and shift of CD4+ helper T cells toward Th1 subtypes. These findings demonstrate FABP4 as a possible early mediator for β cell autoimmunity by facilitating crosstalk between innate and adaptive immune cells, suggesting that pharmacological inhibition of FABP4 may represent a promising therapeutic strategy for autoimmune diabetes.

CD5 levels reveal distinct basal T-cell receptor signals in T cells from non-obese diabetic mice.

Type 1 diabetes in non-obese diabetic (NOD) mice occurs when autoreactive T cells eliminate insulin producing pancreatic β cells. While extensively studied in T-cell receptor (TCR) transgenic mice, the contribution of alterations in thymic selection to the polyclonal T-cell pool in NOD mice is not yet resolved. The magnitude of signals downstream of TCR engagement with self-peptide directs the development of a functional T-cell pool, in part by ensuring tolerance to self. TCR interactions with self-peptide are also necessary for T-cell homeostasis in the peripheral lymphoid organs. To identify differences in TCR signal strength that accompany thymic selection and peripheral T-cell maintenance, we compared CD5 levels, a marker of basal TCR signal strength, on immature and mature T cells from autoimmune diabetes-prone NOD and -resistant B6 mice. The data suggest that there is no preferential selection of NOD thymocytes that perceive stronger TCR signals from self-peptide engagement. Instead, NOD mice have an MHC-dependent increase in CD4+ thymocytes and mature T cells that express lower levels of CD5. In contrast, T cell-intrinsic mechanisms lead to higher levels of CD5 on peripheral CD8+ T cells from NOD relative to B6 mice, suggesting that peripheral CD8+ T cells with higher basal TCR signals may have survival advantages in NOD mice. These differences in the T-cell pool in NOD mice may contribute to the development or progression of autoimmune diabetes.

Inhibition of mitochondrial oxidative metabolism attenuates EMCV replication and protects β-cells from virally mediated lysis

Viral infection is one environmental factor that may contribute to the initiation of pancreatic β-cell destruction during the development of autoimmune diabetes. Picornaviruses, such as encephalomyocarditis virus (EMCV), induce a pro-inflammatory response in islets leading to local production of cytokines, such as IL-1, by resident islet leukocytes. Furthermore, IL-1 is known to stimulate β-cell expression of iNOS and production of the free radical nitric oxide. The purpose of this study was to determine whether nitric oxide contributes to the β-cell response to viral infection. We show that nitric oxide protects β-cells against virally mediated lysis by limiting EMCV replication. This protection requires low micromolar, or iNOS-derived, levels of nitric oxide. At these concentrations nitric oxide inhibits the Krebs enzyme aconitase and complex IV of the electron transport chain. Like nitric oxide, pharmacological inhibition of mitochondrial oxidative metabolism attenuates EMCV-mediated β-cell lysis by inhibiting viral replication. These findings provide novel evidence that cytokine signaling in β-cells functions to limit viral replication and subsequent β-cell lysis by attenuating mitochondrial oxidative metabolism in a nitric oxide–dependent manner.

Development of autoimmune diabetes with severe diabetic ketoacidosis and immune-related thyroiditis secondary to durvalumab: a case report

Immune-mediated endocrinopathies are among the most frequent immune-related adverse events (irAEs) with immune checkpoint inhibitors (ICIs) targeting programmed death-ligand 1 (PD-L1)/PD-1. However, the development of auto-immune diabetes is an uncommon event during PD(L)-1 blockade, either as monotherapy or in combination therapy. Here we report a case of a 75-year-old male with a mediastinal recurrence from a stage IA squamous cell carcinoma of the lung previously treated with stereotactic body radiotherapy (SBRT) who early developed a severe diabetic ketoacidosis (DKA) caused by new-onset auto-immune diabetes, with positive glutamic acid decarboxylase (GAD65) autoantibodies, during durvalumab consolidation therapy after concurrent chemoradiation. The patient had no personal or family history of diabetes or auto-immune diseases and was admitted after the second cycle of durvalumab to the intensive care unit (ICU) with severe DKA. During his hospitalization, insulin and fluid therapy were started and the patient had a favorable clinical course. Durvalumab treatment was interrupted and thyroiditis was verified during follow-up, without anti-thyroid antibodies, that progressed to subsequent hypothyroidism with need of thyroid hormone replacement therapy. This case highlights the rare irAE of autoimmune type 1 diabetes during anti-PD(L)-1 therapy, which can be life-threatening and requires adequate patient education and prompt medical treatment within a multidisciplinary team, including endocrinology and emergency medicine. Besides its low incidence, this case show how irAE must be taken in account about decision of ICI treatment, especially in curative setting, as they can be potentially fatal and impair overall survival. Furthermore, as reported in the present case, multiple endocrine irAEs can occur in the same patient either simultaneously or sequentially, suggesting that active surveillance is needed in those who develop endocrinopathies as a result of ICI treatment. Immune-mediated endocrinopathies are generally irreversible and cause life-long morbidity, which must be taken into consideration when deciding on further lines of treatment.

Neutrophil elastase triggers the development of autoimmune diabetes by exacerbating innate immune responses in pancreatic islets of non-obese diabetic mice.

Type 1 diabetes is an autoimmune disease resulted from self-destruction of insulin-producing pancreatic β cells. However, the pathological pathways that trigger the autoimmune destruction remain poorly understood. Clinical studies have demonstrated close associations of neutrophils and neutrophil elastase (NE) with β-cell autoimmunity in patients with Type 1 diabetes. The present study aims to investigate the impact of NE inhibition on development of autoimmune diabetes in NOD mice. NE pharmacological inhibitor (sivelestat) or biological inhibitor (elafin) was supplemented into NOD mice to evaluate their effects on islet inflammation and diabetogenesis. The impact of NE inhibition on innate and adaptive immune cells was measured with flow cytometry and immunohistochemistry. A significant but transient increase in neutrophil infiltration accompanied with elevated NE activity was observed in the neonatal period of NOD mice. Treatment of NOD mice with sivelestat or elafin at the early age led to a marked reduction in spontaneous development of insulitis and autoimmune diabetes. Mechanistically, inhibition of NE significantly attenuated infiltration of macrophages and islet inflammation, thus ameliorating cytotoxic T cell-mediated autoimmune attack of pancreatic β cells. In vitro studies showed that NE directly induced inflammatory responses in both min6 β cells and RAW264.7 macrophages, and promoted macrophage migration. These findings support an important role of NE in triggering the onset and progression of β-cell autoimmunity, and suggest that pharmacological inhibition of NE may represent a promising therapeutic strategy for treatment of autoimmune diabetes.

DNA demethylation increases NETosis

Neutrophil extracellular traps (NETs) occur during the development of autoimmune diseases, cancer and diabetes. A novel form of cell death that is induced by NETs is called NETosis. Although these diseases are known to have an epigenetic component, epigenetic regulation of NETosis has not previously been explored. In the present study, we investigated the effects of epigenetic change, especially DNA demethylation, on NETosis in neutrophil-like cells differentiated from HL-60 cells, which were incubated for 72 h in the presence of 1.25% DMSO. DMSO-differentiated neutrophil-like cells tended to have increased methylation of genomic DNA. NETosis in the neutrophil-like cells was induced by the treatment with A23187, calcium ionophore, and increased by the addition of the DNMT inhibitor 5-azacytidine (Aza) during differentiation. Interestingly, Aza-stimulated neutrophil-like cell induced NETosis without treatment with A23187. Although reactive oxygen species (ROS), especially superoxide and hypochlorous acid, are important in NETosis induction, treatment with Aza decreased production of ROS, while mitochondria ROS scavenger tended to decrease Aza-induced NETosis. Moreover, the genomic DNA in Aza-stimulated neutrophil-like cell was demethylated, and the expression of peptidylarginine deiminase4 (PAD4) and citrullinated histone H3 (R2+R8+R17) was increased, but myeloperoxidase expression was unaffected. Additionally, PAD4 inhibition tended to decrease Aza-induced NETosis. The DNA demethylation induced by the DNMT inhibitor in neutrophil-like cells enhanced spontaneous NETosis through increasing PAD4 expression and histone citrullination. This study establishes a relationship between NETosis and epigenetics for the first time, and indicates that various diseases implicated to have an epigenetic component might be exacerbated by excessive NETosis also under epigenetic control.

86-OR: High-Fat Diet Prevents Autoimmune Diabetes in NOD Mice

Type 1 diabetes (T1D) has a strong genetic predisposition and requires an environmental trigger to initiate autoimmune destruction of beta cells. The rate of childhood obesity has risen in parallel to the rate of T1D, suggesting high fat diet (HFD) may be an environmental trigger in the development of autoimmune diabetes. Supporting this hypothesis, HFD can induce insulin resistance, beta cell stress, dysfunctional insulin production, and beta cell death. To explore the role of HFD in the development of T1D, 4 week-old non-obese diabetic (NOD) female mice were placed on HFD or chow diet (CD). At 10 weeks of age NOD mice fed with HFD demonstrated a significant increase in body weight and non-fasting blood glucose along with mild glucose intolerance compared with NOD CD fed mice. Histological analysis at 10 weeks of age revealed significantly less pancreatic immune cell infiltration and increased beta cell mass in HFD fed mice compared to CD fed mice. By 15 weeks of age, HFD fed NOD animals demonstrated impaired glucose tolerance similar to CD fed mice, increased glucose-stimulated insulin secretion and total insulin content, and insulin resistance. Surprisingly, at 25 weeks of age the HFD fed NOD mice were completely protected from the development of diabetes, while as expected 70% of NOD CD fed mice had developed diabetes. In summary, this study demonstrates that in the NOD model of T1D HFD reduced islet immune cell infiltration, increased beta cell mass, insulin content and insulin secretion protecting the mice from development of diabetes. The mechanism underlying this protection seems to be two-fold: expansion of beta cell mass and prevention of autoimmune-mediated beta cell death. Our data correlate with other recent studies indicating that early stimulation of beta cell replication can induce immune tolerance in NOD animals preventing T1D. Identification of the mechanisms by which HFD leads to prevention of diabetes in NOD animals may lead to the development of novel therapeutic interventions to prevent T1D in humans. Disclosure A.L. Clark: None. Z. Yan: None. S.X. Chen: None. M. Fuess: None. G. McGinn: None. M.S. Remedi: None. Funding National Institutes of Health (P30DK020579, K12HD076224-04)