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Persistent antigen exposure results in the differentiation of functionally impaired, also termed exhausted, T cells which are maintained by a distinct population of precursors of exhausted T (TPEX) cells. T cell exhaustion is well studied in the context of chronic viral infections and cancer, but it is unclear if and how antigen-driven T cell exhaustion controls progression of autoimmune diabetes and whether this process can be harnessed to prevent diabetes. Using non-obese diabetic (NOD) mice, we show that some CD8+ T cells specific for the islet antigen, islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP) displayed terminal exhaustion characteristics within pancreatic islets but were maintained in the TPEXcell state in peripheral lymphoid organs. To examine the impact of antigen on T cell exhaustion in diabetes, we generated transgenic NOD mice with inducible IGRP expression in peripheral antigen presenting cells. Antigen exposure in the extra-islet environment induced severely exhausted IGRP-specific T cells with reduced ability to produce IFNγ, which protected these mice from diabetes. Our data demonstrate that T cell exhaustion induced by delivery of antigen can be harnessed to prevent autoimmune diabetes.

A relationship between diabetes, glucose and COVID-19 outcomes has been reported in international cohorts. This study aimed to assess the relationship between diabetes, hyperglycaemia and patient outcomes in those hospitalised with COVID-19 during the first year of the Victorian pandemic prior to novel variants and vaccinations.Retrospective cohort study from March to November 2020 across five public health services in Melbourne, Australia.All consecutive adult patients admitted to acute wards of participating institutions during the study period with a diagnosis of COVID-19, comprising a large proportion of patients from residential care facilities and following dexamethasone becoming standard-of-care. Admissions in patients without known diabetes and without inpatient glucose testing were excluded.The DINGO COVID-19 cohort comprised 840 admissions. In 438 admissions (52%), there was no known diabetes or in-hospital hyperglycaemia, in 298 (35%) patients had known diabetes, and in 104 (12%) patients had hyperglycaemia without known diabetes. ICU admission was more common in those with diabetes (20%) and hyperglycaemia without diabetes (49%) than those with neither (11%, P 0.001 for all comparisons). Mortality was higher in those with diabetes (24%) than those without diabetes or hyperglycaemia (16%, P = 0.02) but no difference between those with in-hospital hyperglycaemia and either of the other groups. On multivariable analysis, hyperglycaemia was associated with increased ICU admission (adjusted odds ratio (aOR) 6.7, 95% confidence interval (95% CI) 4.0-12, P 0.001) and longer length of stay (aOR 173, 95% CI 11-2793, P 0.001), while diabetes was associated with reduced ICU admission (aOR 0.55, 95% CI 0.33-0.94, P = 0.03). Neither diabetes nor hyperglycaemia was independently associated with in-hospital mortality.During the first year of the COVID-19 pandemic, in-hospital hyperglycaemia and known diabetes were not associated with in-hospital mortality, contrasting with published international experiences. This likely mainly relates to hyperglycaemia indicating receipt of mortality-reducing dexamethasone therapy. These differences in published experiences underscore the importance of understanding population and clinical treatment factors affecting glycaemia and COVID-19 morbidity within both local and global contexts.

DESIGN A retrospective review of the adverse events (AEs) in 78 patients during the glucagon stimulation test (GST) for the assessment of growth hormone deficiency (GHD) before and after protocol amendments which aimed to reduce AEs in a group of patients with a high prevalence of pituitary hormone deficiencies. PATIENTS Based on our observations of frequent AEs during the standard GST protocol in an initial 25 patients (cohort 1), a modified protocol was introduced to include the routine administration of 20 mg of hydrocortisone pre-GST in a subsequent 53 patients (cohort 2). Post hoc analysis of the effect of glucocorticoid dosing pre-GST on AEs was examined in those receiving

Although immune interventions have shown great promise in type 1 diabetes mellitus (T1D) clinical trials, none are yet in routine clinical use or able to achieve insulin independence in patients. In addition to this, the principles of T1D treatment remain essentially unchanged since the isolation of insulin, almost a century ago. T1D is characterized by insulin deficiency as a result of destruction of insulin-producing beta cells mediated by autoreactive T cells. Therapies that target beta-cell antigen-specific T cells are needed to prevent T1D. CD8+ T-cell exhaustion is an emerging area of research in chronic infection, cancer immunotherapy, and more recently, autoimmunity. Recent data suggest that exhausted T-cell populations are associated with improved markers of T1D. T-cell exhaustion is both characterized and mediated by inhibitory receptors. This review aims to identify which inhibitory receptors may prove useful to induce T-cell exhaustion to treat T1D and identify limitations and gaps in the current literature.

Stimulator of IFN genes (STING) is a central hub for cytosolic nucleic acid sensing and its activation results in upregulation of type I IFN production in innate immune cells. A type I IFN gene signature seen before the onset of type 1 diabetes has been suggested as a driver of disease initiation both in humans and in the NOD mouse model. A possible source of type I IFN is through activation of the STING pathway. Recent studies suggest that STING also has antiproliferative and proapoptotic functions in T cells that are independent of IFN. To investigate whether STING is involved in autoimmune diabetes, we examined the impact of genetic deletion of STING in NOD mice. CRISPR/Cas9 gene editing was used to generate STING-deficient NOD mice. Quantitative real-time PCR was used to assess the level of type I IFN-regulated genes in islets from wild-type and STING-deficient NOD mice. The number of islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP)206-214-specific CD8+ T cells was determined by magnetic bead-based MHC tetramer enrichment and flow cytometry. The incidence of spontaneous diabetes and diabetes after adoptive transfer of T cells was determined. STING deficiency partially attenuated the type I IFN gene signature in islets but did not suppress insulitis. STING-deficient NOD mice accumulated an increased number of IGRP206-214-specific CD8+ T cells (2878 ± 642 cells in NOD.STING−/− mice and 728.8 ± 196 cells in wild-type NOD mice) in peripheral lymphoid tissue, associated with a higher incidence of spontaneous diabetes (95.5% in NOD.STING−/− mice and 86.2% in wild-type NOD mice). Splenocytes from STING-deficient mice rapidly induced diabetes after adoptive transfer into irradiated NOD recipients (median survival 75 days for NOD recipients of NOD.STING−/− mouse splenocytes and 121 days for NOD recipients of NOD mouse splenocytes). Data suggest that sensing of endogenous nucleic acids through the STING pathway may be partially responsible for the type I IFN gene signature but not autoimmunity in NOD mice. Our results show that the STING pathway may play an unexpected intrinsic role in suppressing the number of diabetogenic T cells.

Background: Gestational diabetes mellitus (GDM) management using self-monitoring blood glucose (SMBG) does not normalize pregnancy outcomes. Objective: We aimed to conduct an observational study to...

Interferon gamma (IFNγ) is a proinflammatory cytokine implicated in autoimmune diseases. However, deficiency or neutralization of IFNγ is ineffective in reducing disease. We characterize islet antigen-specific T cells in non-obese diabetic (NOD) mice lacking all three IFN receptor genes. Diabetes is minimally affected, but at 125 days of age, antigen-specific CD8

Background: Experience from first-generation closed-loop (CL) systems informs refinements to enhance glucose control and user acceptance. A next-generation prototype enhanced-hybrid CL (E-...

Aims Aim of this study is to report severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection, responsible for coronavirus disease 2019 (COVID‐19), as a possible cause for type 1 diabetes by providing an illustrative clinical case of a man aged 45 years presenting with antibody‐negative diabetic ketoacidosis post‐recovery from COVID‐19 pneumonia and to explore the potential for SARS‐CoV‐2 to adhere to human islet cells. Methods Explanted human islet cells from three independent solid organ donors were incubated with the SARS‐CoV‐2 spike protein receptor biding domain (RBD) fused to a green fluorescent protein (GFP) or a control‐GFP, with differential adherence established by flow cytometry. Results Flow cytometry revealed dose‐dependent specific binding of RBD‐GFP to islet cells when compared to control‐GFP. Conclusions Although a causal basis remains to be established, our case and in vitro data highlight a potential mechanism by which SARS‐CoV‐2 infection may result in antibody‐negative type 1 diabetes.

Although immune interventions have shown great promise in type 1 diabetes mellitus (T1D) clinical trials, none are yet in routine clinical use or able to achieve insulin independence in patients. In addition to this, the principles of T1D treatment remain essentially unchanged since the isolation of insulin, almost a century ago. T1D is characterized by insulin deficiency as a result of destruction of insulin-producing beta cells mediated by autoreactive T cells. Therapies that target beta-cell antigen-specific T cells are needed to prevent T1D. CD8

Stimulator of IFN genes (STING) is a central hub for cytosolic nucleic acid sensing and its activation results in upregulation of type I IFN production in innate immune cells. A type I IFN gene signature seen before the onset of type 1 diabetes has been suggested as a driver of disease initiation both in humans and in the NOD mouse model. A possible source of type I IFN is through activation of the STING pathway. Recent studies suggest that STING also has antiproliferative and proapoptotic functions in T cells that are independent of IFN. To investigate whether STING is involved in autoimmune diabetes, we examined the impact of genetic deletion of STING in NOD mice.CRISPR/Cas9 gene editing was used to generate STING-deficient NOD mice. Quantitative real-time PCR was used to assess the level of type I IFN-regulated genes in islets from wild-type and STING-deficient NOD mice. The number of islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP)STING deficiency partially attenuated the type I IFN gene signature in islets but did not suppress insulitis. STING-deficient NOD mice accumulated an increased number of IGRPData suggest that sensing of endogenous nucleic acids through the STING pathway may be partially responsible for the type I IFN gene signature but not autoimmunity in NOD mice. Our results show that the STING pathway may play an unexpected intrinsic role in suppressing the number of diabetogenic T cells.

IFN-γ is a potential drug target in type 1 diabetes and this is part of the rationale for trialing JAK inhibitors (JAKi) for treatment of new onset T1D. It regulates migration and adhesion of leucocytes, as well as expression of MHC class I on islet beta cells. However, neither genetic deficiency of IFN-γ nor its receptor in NOD mice modifies disease progression. To understand this paradox we characterised islet antigen-specific T cells in NOD mice lacking the IFN-γ receptor (Ifngr) generated directly in NOD mouse embryos using CRISPR/Cas9 gene editing. Islet antigen-specific CD8+ T cells (proinsulin B15-23 and IGRP206-214) and CD4+ T cells (proinsulin B10-23and BDC2.5 mimotope) were quantified using tetramer enrichment and flow cytometry. At 125 days of age, insulin-specific (177±41 cells in wild type and 1799±1123 cells in Ifngr mutant, p=0.036) and IGRP-specific CD8+ T cells (2524±735 cells in wild type and 30598±10426 cells in Ifngr mutant, p Disclosure T. Kay: None. G. Jhala: None. B. Krishnamurthy: None. H.E. Thomas: None.

Cytokines that signal through the JAK-STAT pathway, such as interferon-γ (IFN-γ) and common γ chain cytokines, play an important role in facilitating the destruction of insulin-secreting β cells by CD8+ T cells in type 1 diabetes. We previously showed that inhibiting JAK1/JAK2 reversed autoimmune insulitis in non-obese diabetic (NOD) mice and also blocked IFN-γ mediated MHC class I upregulation on β cells. Blocking interferons on their own did not prevent diabetes in knockout NOD mice, so we tested whether JAK inhibitor action on signaling downstream of common γ chain family cytokines, including IL-2, IL-21, IL-7 and IL-15, may also affect progression of diabetes in NOD mice. Common γ chain cytokines activate JAK1 and JAK3 to regulate T cell proliferation. We compared JAK1-selective inhibitors with our previous data with JAK1/JAK2 inhibition. JAK1-selective inhibitors reduced IL-21, IL-2 and IL-7 signaling in T cells (p Our results indicate that JAK inhibitors block common γ chain cytokines in lymphocytes and interferons in lymphocytes and β cells and are thus more effective against diabetes pathogenesis than IFNγ receptor deficiency alone. Our studies pave the way for use of this class of drug in clinical trials for type 1 diabetes. Disclosure G. Jhala: None. T. Ge: None. B. Krishnamurthy: None. T. Kay: None. H.E. Thomas: None. Funding National Health and Medical Research Council of Australia (GNT1145507); JDRF (1-SRA-2018-599-S-B)

Background: Immune checkpoint blockade is now established as standard of care in several malignancies. Trials involving combined cytotoxic T lymphocyte associated protein 4 (CTLA4) and programmed cell death protein 1 (PD1) blockade demonstrate improved tumour responses in melanoma but at the cost of severe grade 3-4 immune related adverse events (irAEs) in 55%, and endocrine irAEs in up to 10% [1]. Immune-mediated damage to endocrine glands can be a diagnostic and management challenge. We aimed to review the incidence, biochemical evolution and imaging findings of endocrine toxicity related to combined anti CTLA-4 and anti-PD-1 therapy. Methods: We undertook a retrospective chart review of patients who received combined ipilimumab and nivolumab for metastatic melanoma at a tertiary referral centre between 2016-2019. We recorded onset and duration of abnormal biochemistry in endocrine irAEs, reviewed all available MRI images for pituitary size (mm) and appearance and 18-F FDG PET images for features of hypophysitis, thyroiditis and pancreatitis. Results: 162 patients received combination therapy. At least one irAE was recorded in 135 patients (83%), 100 (62%) required glucocorticoids, and 84 (52%) had an unplanned hospital presentation due to irAEs. Thyroiditis occurred in 50 (30.9%), with median time to onset of 30.9 days (range 1-234 days). 35 cases were identified with routine biochemistry performed every 4-6 weeks. TSH receptor antibody was measured in 13 patients and all were negative. 29 (58%) developed permanent hypothyroidism. Central cortisol deficiency was documented in 31 (19%) with a median time to diagnosis of 67.5 days (range 5-286). 4 cases were diagnosed on routine biochemistry and 14 presented with symptoms prompting investigation. 13 were diagnosed after routine neuroimaging demonstrated a pituitary abnormality, and a further 27 patients without the clinical syndrome had features of hypophysitis on neuroimaging. New onset diabetes occurred in 3 people, in which pancreatic inflammation on imaging was found in 2. A further 3/5 patients with an asymptomatic elevated lipase were found to have abnormal pancreatic imaging. In one patient with no features of endocrine or exocrine failure, there was a significant increase in FDG uptake and a subsequent loss of pancreatic volume. Conclusion: We report real world incidence of endocrine irAEs with combination immunotherapy. Routine biochemistry leads to the detection of some but not all cases. Early recognition and avoidance of unplanned presentations remains a challenge. Opportunistic assessment of endocrine gland appearance on routine imaging studies may provide useful early diagnostic information. Reference: Larkin J, Chiarion-Sileni V, Gonzalez R, Grob JJ, Cowey CL, Lao CD, et al. Combined nivolumab and ipilimumab or monotherapy in untreated melanoma. N Engl J Med. (2015) 1:23-34. 10.1056/NEJMoa1504030

Background: Hypophysitis is one of the commonly reported adverse events related to immune checkpoint inhibitors (ICI), and the incidence is expected to rise with increased use of combined programmed cell death protein 1 (PD1) and cytotoxic T lymphocyte associated protein 4 (CTLA4) blockade. The clinical diagnosis can be delayed due to non-specific symptoms. At our centre, subjects undergo periodic imaging to assess tumour response to ICI. We reviewed whether neuroimaging studies can guide us in the diagnosis of hypophysitis and whether early changes can be detected before the onset of the clinical syndrome. Methods: We retrospectively reviewed the medical charts, biochemistry, structural brain imaging and whole-body positron emission tomography (PET) with specific reference to hypophysitis in 162 patients treated with combination ICI at a tertiary melanoma referral centre. Suspected cases were identified based on meeting one or more of the following criteria: 1) A documented diagnosis of hypophysitis or pituitary dysfunction found on chart review, 2) A relative change in pituitary size or appearance from baseline on neuroimaging studies, or 3) An increase in pituitary maximum standardized uptake value (SUVmax) greater than 25% from baseline on 18F-FDG PET. Results: 58/162 patients (36%) met criteria for suspected hypophysitis. Only 4 patients were identified on routine screening of early morning cortisol. 14 patients presented with symptoms leading to biochemical work up. A further 40 patients were found to have suspicious imaging changes, 13 of which went on to receive a formal diagnosis of hypophysitis. Of the remaining 27 patients, 23 were receiving high dose glucocorticoids for concomitant immune related adverse events at the time of the abnormal imaging study.Conclusion: We report the highest incidence to date of suspected hypophysitis in cohort of patients treated with combination ICI. This study highlights the important role of structural and functional neuroimaging in the early recognition of hypophysitis. Imaging may also play a role when the clinical syndrome is masked by concurrent glucocorticoid use.

Granzyme A is a protease implicated in the degradation of intracellular DNA. Nucleotide complexes are known triggers of systemic autoimmunity, but a role in organ-specific autoimmune disease has not been demonstrated. To investigate whether such a mechanism could be an endogenous trigger for autoimmunity, we examined the impact of granzyme A deficiency in the NOD mouse model of autoimmune diabetes. Granzyme A deficiency resulted in an increased incidence in diabetes associated with accumulation of ssDNA in immune cells and induction of an interferon response in pancreatic islets. Central tolerance to proinsulin in transgenic NOD mice was broken on a granzyme A–deficient background. We have identified a novel endogenous trigger for autoimmune diabetes and an in vivo role for granzyme A in maintaining immune tolerance.

CD8+ T cells play a central role in beta-cell destruction in type 1 diabetes. CD8+ T cells use two main effector pathways to kill target cells, perforin plus granzymes and FAS ligand (FASL). We and others have established that in non-obese diabetic (NOD) mice, perforin is the dominant effector molecule by which autoreactive CD8+ T cells kill beta cells. However, blocking FASL pharmacologically was shown to protect NOD mice from diabetes, indicating that FASL may have some role. FASL can engage with its receptor FAS on target cells either as membrane bound or soluble FASL. It has been shown that membrane-bound FASL is required to stimulate FAS-induced apoptosis in target cells, whereas excessive soluble FASL can induce NF-κB-dependent gene expression and inflammation. Because islet inflammation is a feature of autoimmune diabetes, we tested whether soluble FASL could be important in disease pathogenesis independent of its cell death function. We generated NOD mice deficient in soluble FASL, while maintaining expression of membrane-bound FASL due to a mutation in the FASL sequence required for cleavage by metalloproteinase. NOD mice lacking soluble FASL had normal numbers of lymphocytes in their spleen and thymus. Soluble FASL deficient NOD mice had similar islet inflammation as wild-type NOD mice and were not protected from diabetes. Our data indicate that soluble FASL is not required in development of autoimmune diabetes.

Background: A missed or late meal insulin bolus can impact glycemia in type 1 diabetes (T1D). Aim: To study glucose control after missed and late meal boluses in T1D adults using a prototype enhanced hybrid closed-loop (E-HCL) system (Medtronic) providing automated basal insulin and correction boluses. Methods: Twelve T1D adults (median HbA1c 6.8% [IQR 6.2-7.2] | 51mmol/mol [44-55] participated. After 1-week run-in at home in Open Loop, E-HCL was activated during 1-week supervised hotel phase followed by 3 weeks free-living at-home. Participants consumed a standardized 40g carbohydrate dinner in the supervised phase. Four hours of post-prandial glucose data following a standard bolus pre-meal in E-HCL at home were compared in a pairwise manner to 1) Pre-meal bolus in Open Loop Run-In; 2) 20minute Late bolus in E-HCL supervised; 3) Missed bolus in E-HCL supervised using Wilcoxon Signed-Rank Test. Results: Late bolus was associated with mild hypoglycemia and higher glucose variability; missed bolus was associated with hyperglycemia (Table). Overall time in CL was 99.98%. E-HCL at home vs. Open Loop (run-in) had greater time-in-70-180mg/dL range (85.3 vs. 75.0%, p=0.003). There was no severe hypoglycemia or ketoacidosis. Conclusions: While glucose excursions were modest, the administration and timing of meal boluses influenced post-meal glycemia in well-controlled T1D adults using E-HCL. Disclosure M.H. Lee: Research Support; Self; Medtronic. Speaker's Bureau; Self; AstraZeneca. S. Vogrin: None. B. Paldus: Other Relationship; Self; Australian Diabetes Society, JDRF, Medtronic. H. Jones: None. V.R. Obeyesekere: None. C.M. Sims: Stock/Shareholder; Self; Medtronic. S.A. Wyatt: Other Relationship; Self; Animas Corporation, Medtronic. G.M. Ward: None. S.A. McAuley: Research Support; Self; JDRF, Medtronic. Speaker's Bureau; Self; Australian Diabetes Society, Eli Lilly and Company. R. MacIsaac: Advisory Panel; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Novo Nordisk Inc. Speaker's Bureau; Self; AstraZeneca, Novo Nordisk Inc. Other Relationship; Self; AstraZeneca, Novo Nordisk Inc. B. Krishnamurthy: None. V. Sundararajan: None. A. Jenkins: Advisory Panel; Self; Abbott, Australian Diabetes Society, Medtronic. Research Support; Self; Abbott, GlySens Incorporated, Medtronic, Mylan. Speaker's Bureau; Self; Eli Lilly and Company, Novo Nordisk Inc. D.N. O'Neal: None.

Antigen-specific immune tolerance promises to provide safe and effective therapies to prevent type 1 diabetes (T1D). Antigen-specific therapy requires two components: well-defined, clinically relevant autoantigens; and safe approaches to inducing tolerance in T cells specific for these antigens. Proinsulin is a critical autoantigen in both NOD mice, based on knockout mouse studies and induction of immune tolerance to proinsulin preventing disease whereas most antigens cannot, and also in human T1D based on proinsulin-specific T cells being found in the islets of affected individuals and the early appearance of insulin autoantibodies. Effective antigen-specific therapies that prevent T1D in humans have not yet been developed although doubt remains about the best molecular form of the antigen, the dose and the route of administration. Preclinical studies suggest that antigen specific therapy is most useful when administered before onset of autoimmunity but this time-window has not been tested in humans until the recent "pre-point" study. There may be a 'window of opportunity' during the neonatal period when 'vaccine' like administration of proinsulin for a short period may be sufficient to prevent diabetes. After the onset of autoimmunity, naive antigen-specific T cells have differentiated into antigen-experienced memory cells and the immune responses have spread to multiple antigens. Induction of tolerance at this stage becomes more difficult although recent studies have suggested generation of antigen-specific TR1 cells can inhibit memory T cells. Preclinical studies are required to identify additional 'help' that is required to induce tolerance to memory T cells and develop protocols for effective therapy in individuals with established autoimmunity.

Type 1 diabetes (T1D) is an autoimmune disease in which insulin-producing beta cells, found within the islets of Langerhans in the pancreas, are destroyed by islet-infiltrating T cells. Identifying the antigenic targets of beta-cell reactive T cells is critical to gain insight into the pathogenesis of T1D and develop antigen-specific immunotherapies. Several lines of evidence indicate that insulin is an important target of T cells in T1D. Because many human islet-infiltrating CD4(+) T cells recognize C-peptide–derived epitopes, we hypothesized that full-length C-peptide (PI(33–63)), the peptide excised from proinsulin as it is converted to insulin, is a target of CD4(+) T cells in people with T1D. CD4(+) T cell responses to full-length C-peptide were detected in the blood of: 14 of 23 (>60%) people with recent-onset T1D, 2 of 15 (>13%) people with long-standing T1D, and 1 of 13 (

Trinh et al. (1) have described normalization of plasma glucose concentrations coinciding with administration of the tumor necrosis factor (TNF)-α inhibitor infliximab in a patient who had developed diabetes after treatment with immune checkpoint inhibitors (CPI). Diabetes associated with programmed cell death (PD)-1/PD-ligand 1 inhibition is a significant complication occurring in around 0.9% of patients. The classic presentation is acute rise in blood glucose concentration with relatively low HbA1c and steroid-unresponsive progression to permanent islet failure. In a cohort of 64 patients, C-peptide was suppressed in more than 90% and GAD autoantibody was present in approximately half; 62% expressed the high-risk class II …

BCL-2 proteins are known to engage each other to determine the fate of a cell after a death stimulus. However, their evolutionary conservation and the many other reported binding partners suggest an additional function not directly linked to apoptosis regulation. To identify such a function, we studied mice lacking the BH3-only protein BIM. BIM−/− cells had a higher mitochondrial oxygen consumption rate that was associated with higher mitochondrial complex IV activity. The consequences of increased oxygen consumption in BIM−/− mice were significantly lower body weights, reduced adiposity and lower hepatic lipid content. Consistent with reduced adiposity, BIM−/− mice had lower fasting blood glucose, improved insulin sensitivity and hepatic insulin signalling. Lipid oxidation was increased in BIM−/− mice, suggesting a mechanism for their metabolic phenotype. Our data suggest a role for BIM in regulating mitochondrial bioenergetics and metabolism and support the idea that regulation of metabolism and cell death are connected.

Type 1 diabetes results from destruction of pancreatic beta cells by autoreactive T cells. Both CD4(+) and CD8(+) T cells have been shown to mediate beta-cell killing. While CD8(+) T cells can directly recognize MHC class I on beta cells, the interaction between CD4(+) T cells and beta cells remains unclear. Genetic association studies have strongly implicated HLA-DQ alleles in human type 1 diabetes. Here we studied MHC class II expression on beta cells in nonobese diabetic mice that were induced to develop diabetes by diabetogenic CD4(+) T cells with T-cell receptors that recognize beta-cell antigens. Acute infiltration of CD4(+) T cells in islets occurred with rapid onset of diabetes. Beta cells from islets with immune infiltration expressed MHC class II mRNA and protein. Exposure of beta cells to IFN-γ increased MHC class II gene expression, and blocking IFN-γ signaling in beta cells inhibited MHC class II upregulation. IFN-γ also increased HLA-DR expression in human islets. MHC class II(+) beta cells stimulated the proliferation of beta-cell-specific CD4(+) T cells. Our study indicates that MHC class II molecules may play an important role in beta-cell interaction with CD4(+) T cells in the development of type 1 diabetes.

Type 1 diabetes is an autoimmune disease characterised by selective destruction of pancreatic beta cells by the immune system. The transcription factor nuclear factor-kappa B (NF-κB) regulates innate and adaptive immune responses. Using gene targeting and in vitro analysis of pancreatic islets and immune cells, NF-κB activation has been implicated in type 1 diabetes development. Here we use a non-obese diabetic (NOD) mouse model that expresses a luciferase reporter of transcriptionally active NF-κB to determine its activation in vivo during development of diabetes. Increased luciferase activity was readily detected upon treatment with Toll-like receptor ligands in vitro and in vivo, indicating activation of NF-κB. However, activated NF-κB was detectable at low levels above background in unmanipulated NOD mice, but did not vary with age, despite the progression of inflammatory infiltration in islets over time. NF-κB was highly activated in an accelerated model of type 1 diabetes that requires CD4+ T cells and inflammatory macrophages. These data shed light on the nature of the inflammatory response in the development of type 1 diabetes.

CD8+ T cells are critical in human type 1 diabetes and in the NOD mouse. In this study, we elucidated the natural history of islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP)-specific CD8+ T cells in NOD diabetes using MHC-tetramer technology. IGRP206–214-specific T cells in the peripheral lymphoid tissue increased with age, and their numbers correlated with insulitis progression. IGRP206–214-specific T cells in the peripheral lymphoid tissue expressed markers of chronic Ag stimulation, and their numbers were stable after diagnosis of diabetes, consistent with their memory phenotype. IGRP206–214-specific T cells in NOD mice expand, acquire the phenotype of effector-memory T cells in the islets, and emigrate to the peripheral lymphoid tissue. Our observations suggest that enumeration of effector-memory T cells of multiple autoantigen specificities in the periphery of type 1 diabetic subjects could be a reliable reporter for progression of islet pathology.

Type 1 diabetes is caused by immune-mediated loss of pancreatic beta cells. It has been proposed that inflammatory cytokines play a role in killing beta cells. Expression of interleukin (IL)-1 and tumor necrosis factor (TNF-α) has been detected in islets from patients with type 1 diabetes, and these cytokines can induce beta cell death in vitro. We produced nonobese diabetic (NOD) mice lacking receptors for these cytokines. Islets from mice lacking IL-1RI or TNFR1 were killed when transplanted into wild-type NOD mice, suggesting that cytokine action on beta cells is not required for killing. Mice lacking TNFR1 did not develop diabetes, and mice lacking IL-1R had delayed onset of diabetes, indicating a role for these cytokines in disease development. TNFR1-deficient mice had an increased number of CD4(+) CD25(+) FoxP3(+) regulatory T cells with enhanced suppressive capacity. IL-1 was produced at higher levels in NOD mice and resulted in dilution of suppressor function of CD4(+) CD25(+) FoxP3(+) regulatory T cells. Our data suggest that blocking inflammatory cytokines may increase the capacity of the immune system to suppress type 1 diabetes through regulatory T cells.

Recent advances in immunotherapeutics have not yet changed the routine management of autoimmune type 1 diabetes. There is an opportunity to repurpose therapeutics used to treat other diseases to treat type 1 diabetes, especially when there is evidence for overlapping mechanisms. Janus kinase (JAK) 1/JAK2 inhibitors are in development or clinical use for indications including rheumatoid arthritis. There is good evidence for activation of the JAK1/JAK2 and signal transducer and activator of transcription (STAT) 1 pathway in human type 1 diabetes and in mouse models, especially in β-cells. We tested the hypothesis that using these drugs to block the JAK-STAT pathway would prevent autoimmune diabetes. The JAK1/JAK2 inhibitor AZD1480 blocked the effect of cytokines on mouse and human β-cells by inhibiting MHC class I upregulation. This prevented the direct interaction between CD8+ T cells and β-cells, and reduced immune cell infiltration into islets. NOD mice treated with AZD1480 were protected from autoimmune diabetes, and diabetes was reversed in newly diagnosed NOD mice. This provides mechanistic groundwork for repurposing clinically approved JAK1/JAK2 inhibitors for type 1 diabetes.

High-affinity self-reactive thymocytes are purged in the thymus, and residual self-reactive T cells, which are detectable in healthy subjects, are controlled by peripheral tolerance mechanisms. Breakdown in these mechanisms results in autoimmune disease, but antigen-specific therapy to augment natural mechanisms can prevent this. We aimed to determine when antigen-specific therapy is most effective. Islet autoantigens, proinsulin (PI), and islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP) were expressed in the antigen-presenting cells (APCs) of autoimmune diabetes-prone nonobese diabetic (NOD) mice in a temporally controlled manner. PI expression from gestation until weaning was sufficient to completely protect NOD mice from diabetes, insulitis, and development of insulin autoantibodies. Insulin-specific T cells were significantly diminished, were naive, and did not express IFN-γ when challenged. This long-lasting effect from a brief period of treatment suggests that autoreactive T cells are not produced subsequently. We tracked IGRP206–214-specific CD8+ T cells in NOD mice expressing IGRP in APCs. When IGRP was expressed only until weaning, IGRP206–214-specific CD8+ T cells were not detected later in life. Thus, anti-islet autoimmunity is determined during early life, and autoreactive T cells are not generated in later life. Bolstering tolerance to islet antigens in the perinatal period is sufficient to impart lasting protection from diabetes.