Enterovirus infection, CXC chemokine ligand 10 (CXCL10), and CXCR3 circuit: a mechanism of accelerated beta-cell failure in fulminant type 1 diabetes

Investigation of missense mutation-related type 1 diabetes mellitus through integrating genomic databases and bioinformatic approach

Though genes are already known to be responsible for type 1 diabetes mellitus (T1DM), the knowledge of missense mutation of that disease gene has still to be under covered. A genomic database and a bioinformatics-based approach are integrated in the present study in order to address this issue. Initially, nine variants associated with T1DM were retrieved from the GWAS catalogue. Different genomic algorithms such as PolyPhen2.0, SNPs and GTEx analyser programs were used to study the structural and functional effects of these mutations. Subsequently, SNPnexus was also employed to understand the effect of these mutations on the function of the expressed protein. Nine missense variants of T1DM were identified using the GWAS catalogue database. Among these nine SNPs, three were predicted to be related to the progression of T1DM disease by affecting the protein level. TYK2 gene variants with SNP rs34536443 were thought to have a probably damaging effect. Meanwhile, both COL4A3 and IFIH1 genes with SNPs rs55703767 and rs35667974, respectively, might alter protein function through a possibly damaging prediction. Among the variants of the three genes, the TYK2 gene with SNP rs34536443 had the strongest contribution in affecting the development of T1DM, with a score of 0.999. We sincerely hope that the results could be of immense importance in understanding the genetic basis of T1DM.

Network approach reveals preferential T-cell and macrophage association with α-linked β-cells in early stage of insulitis in NOD mice

One of the challenges in studying islet inflammation-insulitis-is that it is a transient phenomenon. Traditional reporting of the insulitis progression is based on cumulative, donor-averaged values of leucocyte density in the vicinity of pancreatic islets, that hinder intra- and inter-islet heterogeneity of disease progression. Here, we aimed to understand why insulitis is non-uniform, often with peri-insulitis lesions formed on one side of an islet. To achieve this, we demonstrated the applicability of network theory in detangling intra-islet multi-cellular interactions during insulitis. Specifically, we asked the question "What is unique about regions of the islet that interact with immune cells first". This study utilized the non-obese diabetic mouse model of type one diabetes and examined the interplay among α-, β-, T-cells, myeloid cells, and macrophages in pancreatic islets during the progression of insulitis. Disease evolution was tracked based on the T/β cell ratio in individual islets. In the early stage, we found that immune cells are preferentially interacting with α-cell-rich regions of an islet. At the islet periphery α-linked β-cells were found to be targeted significantly more compared to those without α-cell neighbors. Additionally, network analysis revealed increased T-myeloid, and T-macrophage interactions with all β-cells.

Islet-Resident Memory T Cells Orchestrate the Immunopathogenesis of Type 1 Diabetes through the FABP4-CXCL10 Axis

Type 1 diabetes (T1D) is a chronic disease characterized by self-destruction of insulin-producing pancreatic β cells by cytotoxic T cell activity. However, the pathogenic mechanism of T cell infiltration remains obscure. Recently, tissue-resident memory T (TRM) cells have been shown to contribute to cytotoxic T cell recruitment. TRM cells are found present in human pancreas and are suggested to modulate immune homeostasis. Here, the role of TRM cells in the development of T1D is investigated. The presence of TRM cells in pancreatic islets is observed in non-obese diabetic (NOD) mice before T1D onset. Mechanistically, elevated fatty acid-binding protein 4 (FABP4) potentiates the survival and alarming function of TRM cells by promoting fatty acid utilization and C-X-C motif chemokine 10 (CXCL10) secretion, respectively. In NOD mice, genetic deletion of FABP4 or depletion of TRM cells using CD69 neutralizing antibodies resulted in a similar reduction of pancreatic cytotoxic T cell recruitment, a delay in diabetic incidence, and a suppression of CXCL10 production. Thus, targeting FABP4 may represent a promising therapeutic strategy for T1D.

A Case of Fulminant Type 1 Diabetes with Transient Production of Anti-Glutamic Acid Decarboxylase Antibody

BACKGROUND Fulminant type 1 diabetes is characterized by a low prevalence of autoantibodies, and was originally described as a nonautoimmune subtype of type 1 diabetes. Herein, we report a case in which we observed the process of extremely rapid onset of diabetes and early decline in anti-glutamic acid decarboxylase (GAD) antibody titers during the inpatient stay. CASE REPORT A 61-year-old man was brought to our hospital with marked hyperglycemia (1327 mg/dL), ketonemia (3-hydroxybutyrate: 14 012 µmol/L), and moderately elevated HbA1c (7.2%) and glycoalbumin (22.3%). C-peptide levels were undetectable. He had suffered from thirst, polyuria, and fatigue for 2 days. Abrupt onset was proven by the clinical data when he visited the hospital with respiratory symptoms 6 days before his admission; plasma glucose, glycoalbumin, C-peptide, and insulin levels were 117 mg/dL, 13.0%, 5.07 ng/mL, and 24.4 µIU/mL, respectively. The anti-GAD antibody titer measured by enzyme-linked immunosorbent assay was 111 U/mL at admission, 22.8 U/mL 2 weeks after admission, and negative 1 year later. He had a susceptible haplotype DRB1*09: 01-DQB1*03: 03, which is significantly more common in anti-GAD antibody-positive patients with fulminant type 1 diabetes. CONCLUSIONS The early decline of anti-GAD antibody titer likely reflected rapid and complete beta cell loss. The sequential metabolic and immunological observation in this case may provide insight into the pathogenesis of fulminant type 1 diabetes.

Network approach reveals preferential T-cell and macrophage association with α-linked β-cells in early stage of insulitis in NOD mice

One of the challenges in studying islet inflammation - insulitis - is that it is a transient phenomenon. Traditional reporting of the insulitis progression is based on cumulative, donor-averaged values of leucocyte density in the vicinity of pancreatic islets, that hinders intra- and inter-islet heterogeneity of disease progression. Here, we aimed to understand why insulitis is non-uniform, often with peri-insulitis lesions formed on one side of an islet. To achieve this, we demonstrated applicability of network theory in detangling intra-islet multi-cellular interactions during insulitis. Specifically, we asked the question "what is unique about regions of the islet which interact with immune cells first". This study utilized the non-obese diabetic mouse model of type one diabetes and examined the interplay among α-, β-, T-cells, myeloid cells, and macrophages in pancreatic islets during the progression of insulitis. Disease evolution was tracked based on T/β cell ratio in individual islets. In the early stage, we found that immune cells are preferentially interacting with α-cell-rich regions of an islet. At the islet periphery α-linked β-cells were found to be targeted significantly more compared to those without α-cell neighbors. Additionally, network analysis revealed increased T-myeloid, and T-macrophage interactions with all β-cells.

Differentiation of Pancreatic Beta Cells: Dual Acting of Inflammatory Factors

In the past decades, scientists have made outstanding efforts to treat diabetes. However, diabetes treatment is still far from satisfactory due to the complex nature of the disease and the challenges encountered in resolving it. Inflammatory factors are key regulators of the immune system's response to pathological insults, organ neogenesis, rejuvenation of novel cells to replace injured cells and overwhelming disease conditions. Currently, the available treatments for type 1 diabetes include daily insulin injection, pancreatic beta cell or tissue transplantation, and gene therapy. Cell therapy, exploiting differentiation, and reprogramming various types of cells to generate pancreatic insulin-producing cells are novel approaches for the treatment of type 1 diabetes. A better understanding of the inflammatory pathways offers valuable and improved therapeutic options to provide more advanced and better treatments for diabetes. In this review, we investigated different types of inflammatory factors that participate in the pathogenesis of type 1 diabetes, their possible dual impacts on the differentiation, reprogramming, and fusion of other stem cell lines into pancreatic insulin-producing beta cells, and the possibility of applying these factors to improve the treatment of this disease.

Combination treatment of a novel CXCR3 antagonist ACT-777991 with an anti-CD3 antibody synergistically increases persistent remission in experimental models of type 1 diabetes

Treatment of patients with recent-onset type 1 diabetes with an anti-CD3 antibody leads to the transient stabilization of C-peptide levels in responder patients. Partial efficacy may be explained by the entry of islet-reactive T-cells spared by and/or regenerated after the anti-CD3 therapy. The CXCR3/CXCL10 axis has been proposed as a key player in the infiltration of autoreactive T cells into the pancreatic islets followed by the destruction of β cells. Combining the blockade of this axis using ACT-777991, a novel small-molecule CXCR3 antagonist, with anti-CD3 treatment may prevent further infiltration and β-cell damage and thus, preserve insulin production. The effect of anti-CD3 treatment on circulating T-cell subsets, including CXCR3 expression, in mice was evaluated by flow cytometry. Anti-CD3/ACT-777991 combination treatment was assessed in the virally induced RIP-LCMV-GP and NOD diabetes mouse models. Treatments started at disease onset. The effects on remission rate, blood glucose concentrations, insulitis, and plasma C-peptide were evaluated for the combination treatment and the respective monotherapies. Anti-CD3 treatment induced transient lymphopenia but spared circulating CXCR3+ T cells. Combination therapy in both mouse models synergistically and persistently reduced blood glucose concentrations, resulting in increased disease remission rates compared to each monotherapy. At the study end, mice in disease remission demonstrated reduced insulitis and detectable plasma C-peptide levels. When treatments were initiated in non-severely hyperglycemic NOD mice at diabetes onset, the combination treatment led to persistent disease remission in all mice. These results provide preclinical validation and rationale to investigate the combination of ACT-777991 with anti-CD3 for the treatment of patients with recent-onset diabetes.

Distinct transcriptomic profiles in children prior to the appearance of type 1 diabetes-linked islet autoantibodies and following enterovirus infection

Although the genetic basis and pathogenesis of type 1 diabetes have been studied extensively, how host responses to environmental factors might contribute to autoantibody development remains largely unknown. Here, we use longitudinal blood transcriptome sequencing data to characterize host responses in children within 12 months prior to the appearance of type 1 diabetes-linked islet autoantibodies, as well as matched control children. We report that children who present with insulin-specific autoantibodies first have distinct transcriptional profiles from those who develop GADA autoantibodies first. In particular, gene dosage-driven expression of GSTM1 is associated with GADA autoantibody positivity. Moreover, compared with controls, we observe increased monocyte and decreased B cell proportions 9-12 months prior to autoantibody positivity, especially in children who developed antibodies against insulin first. Lastly, we show that control children present transcriptional signatures consistent with robust immune responses to enterovirus infection, whereas children who later developed islet autoimmunity do not. These findings highlight distinct immune-related transcriptomic differences between case and control children prior to case progression to islet autoimmunity and uncover deficient antiviral response in children who later develop islet autoimmunity.

Fulminant Type 1 Diabetes-East and West

Fulminant type 1 diabetes is a subtype of type 1 diabetes in which beta cells are destroyed within days or a few weeks. The first criterion indicates a rise in blood glucose levels shown in the patient's history. The second suggests that the increase occurs suddenly within a very short period, as shown by the laboratory findings of the discrepancy between the glycated hemoglobin concentration and plasma glucose level. The third indicates a marked reduction in endogenous insulin secretion, which indicates almost complete destruction of beta cells. Fulminant type 1 diabetes is a common subtype in East Asian countries, including Japan, but rare in Western countries. Class II human leukocyte antigen and other genetic factors may have contributed to the skewed distribution. Environmental factors may also be involved including entero and herpes viruses and immune regulation during drug-induced hypersensitivity syndrome; pregnancy may also affect it. In contrast, treatment with an immune checkpoint inhibitor of the anti-programmed cell death 1 antibody induces similar characteristics and incidence of diabetes as fulminant type 1 diabetes. Further studies are needed to clarify the etiology and clinical characteristics of fulminant type 1 diabetes. Although the incidence of this disease differs between the East and West, it is life-threatening; thus, it is important to diagnose fulminant type 1 diabetes without delay and treat it appropriately.

Monitoring immunomodulation strategies in type 1 diabetes

Type 1 diabetes (T1D) is a T-cell mediated autoimmune disease. Short-term treatment with agents targeting T cells, B cells and inflammatory cytokines to modify the disease course resulted in a short-term pause in disease activity. Lessons learnt from these trials will be discussed in this review. It is expected that effective disease-modifying agents will become available for use in earlier stages of T1D. Progress has been made to analyze antigen-specific T cells with standardization of T cell assay and discovery of antigen epitopes but there are many challenges. High-dimensional profiling of gene, protein and TCR expression at single cell level with innovative computational tools should lead to novel biomarker discovery. With this, assays to detect, quantify and characterize the phenotype and function of antigen-specific T cells will continuously evolve. An improved understanding of T cell responses will help researchers and clinicians to better predict disease onset, and progression, and the therapeutic efficacy of interventions to prevent or arrest T1D.

Bi-glandular and persistent enterovirus infection and distinct changes of the pancreas in slowly progressive type 1 diabetes mellitus

In slowly progressive type 1 diabetes mellitus (SPIDDM), the pancreas shows sustained islet inflammation, pancreatitis, pancreatic acinar cell metaplasia/dysplasia (ADM), and intraepithelial neoplasia (PanIN), a precancerous lesion. The mechanisms underlying these changes remain unclear. The presence of enterovirus (EV) encoded-capsid protein 1 (VP1) and -2A protease (2A^pro) and the innate immune responses of the pancreas were studied using immunohistochemistry and in situ hybridization in 12 SPIDDM and 19 non-diabetic control pancreases. VP1, 2A^pro, and EV-RNA were detected in islets and the exocrine pancreas in all SPIDDM pancreases. Innate immune receptor, melanoma differentiation-associated gene 5 (MDA5), and interferon (IFN)-beta1 were intensified in the islets of SPIDDM patients with short disease duration. However, expressions of MDA5 and IFN-beta1were suppressed in those with longer disease duration. CD3⁺ T cell infiltration was observed in the VP1- and insulin-positive islets (insulitis) and exocrine acinar cells. CD11c⁺ dendritic cells (DCs) in islets were scarce in long-term SPIDDM. This study showed the consistent presence of EV, suggesting an association with inflammatory changes in the endocrine and exocrine pancreas in SPIDDM. Suppressed expressions of MDA5 and IFN-beta1, as well as decreased numbers of DCs in the host cells, may contribute to persistent EV infection and induction of ADM/PanIN lesions, which may potentially provide a scaffold for pancreatic neoplasms.

Re-Enlightenment of Fulminant Type 1 Diabetes under the COVID-19 Pandemic

Fulminant type 1 diabetes (FT1D) is a subtype of type 1 diabetes (T1D) that is characterized by the rapid progression to diabetic ketoacidosis against the background of rapid and almost complete pancreatic islet destruction. The HbA1c level at FT1D onset remains normal or slightly elevated despite marked hyperglycemia, reflecting the rapid clinical course of the disease, and is an important marker for diagnosis. FT1D often appears following flu-like symptoms, and there are many reports of its onset being linked to viral infections. In addition, disease-susceptibility genes have been identified in FT1D, suggesting the involvement of host factors in disease development. In most cases, islet-related autoantibodies are not detected, and histology of pancreatic tissue reveals macrophage and T cell infiltration of the islets in the early stages of FT1D, suggesting that islet destruction occurs via an immune response different from that occurring in autoimmune type 1 diabetes. From 2019, coronavirus disease 2019 (COVID-19) caused by the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) spread worldwide and became a serious problem. Reports on the association between SARS-CoV-2 and T1D are mixed, with some suggesting an increase in T1D incidence due to the COVID-19 pandemic. When discussing the association between COVID-19 and T1D, it is also necessary to focus on FT1D. However, it is not easy to diagnose this subtype without understanding the concept. Therefore, authors hereby review the concept and the latest findings of FT1D, hoping that the association between COVID-19 and T1D will be adequately evaluated in the future.

The interferon regulatory factors, a double-edged sword, in the pathogenesis of type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease resulted from the unrestrained inflammatory attack towards the insulin-producing islet β cells. Although the exact etiology underlying T1D remains elusive, viral infections, especially those specific strains of enterovirus, are acknowledged as a critical environmental cue involved in the early phase of disease initiation. Viral infections could either directly impede β cell function, or elicit pathological autoinflammatory reactions for β cell killing. Autoimmune responses are bolstered by a massive body of virus-derived exogenous pathogen-associated molecular patterns (PAMPs) and the presence of β cell-derived damage-associated molecular patterns (DAMPs). In particular, the nucleic acid components and the downstream nucleic acid sensing pathways serve as the major effector mechanism. The endogenous retroviral RNA, mitochondrial DNA (mtDNA) and genomic fragments generated by stressed or dying β cells induce host responses reminiscent of viral infection, a phenomenon termed as viral mimicry during the early stage of T1D development. Given that the interferon regulatory factors (IRFs) are considered as hub transcription factors to modulate immune responses relevant to viral infection, we thus sought to summarize the critical role of IRFs in T1D pathogenesis. We discuss with focus for the impact of IRFs on the sensitivity of β cells to cytokine stimulation, the vulnerability of β cells to viral infection/mimicry, and the intensity of immune response. Together, targeting certain IRF members, alone or together with other therapeutics, could be a promising strategy against T1D.

A Comprehensive Review of the Evolution of Insulin Development and Its Delivery Method

The year 2021 marks the 100th anniversary of the momentous discovery of insulin. Through years of research and discovery, insulin has evolved from poorly defined crude extracts of animal pancreas to recombinant human insulin and analogues that can be prescribed and administered with high accuracy and efficacy. However, there are still many challenges ahead in clinical settings, particularly with respect to maintaining optimal glycemic control whilst minimizing the treatment-related side effects of hypoglycemia and weight gain. In this review, the chronology of the development of rapid-acting, short-acting, intermediate-acting, and long-acting insulin analogues, as well as mixtures and concentrated formulations that offer the potential to meet this challenge, are summarized. In addition, we also summarize the latest advancements in insulin delivery methods, along with advancement to clinical trials. This review provides insights on the development of insulin treatment for diabetes mellitus that may be useful for clinicians in meeting the needs of their individual patients. However, it is important to note that as of now, none of the new technologies mentioned have superseded the existing method of subcutaneous administration of insulin.

The CXCL10/CXCR3 Axis Promotes Disease Pathogenesis in Mice upon CVA2 Infection

Coxsackievirus A2 (CVA2) is an emerging pathogen that results in hand-foot-and-mouth disease (HFMD) outbreaks. Systemic inflammatory response and central nervous system inflammation are the main pathological features of fatal HFMD. However, the immunopathogenesis of CVA2 infection is poorly understood. We first detected the transcriptional levels of 81 inflammation-related genes in neonatal mice with CVA2 infection. Remarkably, CVA2 induced higher expression of chemokine (C-X-C motif) ligand 10 (CXCL10) in multiple organs and tissues. CXCL10 acts through its cognate receptor chemokine (C-X-C motif) receptor 3 (CXCR3) and regulates immune responses. CXCL10/CXCR3 activation contributes to the pathogenesis of many inflammatory diseases. Next, we found CXCL10 and CXCR3 expression to be significantly elevated in the organs and tissues from CVA2-infected mice at 5 days postinfection (dpi) using immunohistochemistry (IHC). To further explore the role of CXCL10/CXCR3 in CVA2 pathogenesis, an anti-CXCR3 neutralizing antibody (αCXCR3) or IgG isotype control antibody was used to treat CVA2-infected mice on the same day as infection and every 24 h until 5 dpi. Our results showed that αCXCR3 therapy relieved the clinical manifestations and pathological damage and improved the survival rate of CVA2-infected mice. Additionally, αCXCR3 treatment reduced viral loads and reversed the proinflammatory cytokine (interleukin 6 [IL-6], tumor necrosis factor alpha [TNF-α], and IL-1β) expression, apoptosis, and inflammatory cell infiltration induced by CVA2. Collectively, our study presents evidence for the involvement of the CXCL10/CXCR3 axis in CVA2 pathogenesis. The activation of CXCL10/CXCR3 contributes to CVA2 pathogenesis by inducing apoptosis, proinflammatory cytokine expression, and inflammatory cell infiltration, which can be reversed by αCXCR3 therapy. This study provides new insight into the pathogenesis of HFMD, which has an important guiding significance for the treatment of HFMD. IMPORTANCE Systemic inflammatory response and central nervous system inflammation are the main pathological features of fatal HFMD cases. We detected the expression of 81 inflammation-related genes and found higher expression of CXCL10 in CVA2-infected mice. Next, we confirmed CXCL10/CXCR3 activation using immunohistochemistry and found that anti-CXCR3 neutralizing antibody (αCXCR3) therapy could relieve the clinical manifestations and pathological damage and improve the survival rate of CVA2-infected mice. Additionally, αCXCR3 treatment reduced viral loads and reversed the proinflammatory cytokine (IL-6, TNF-α, and IL-1β) expression, apoptosis, and inflammatory cell infiltration induced by CVA2. Collectively, our study presents the first evidence for the involvement of the CXCL10/CXCR3 axis in CVA2 pathogenesis. The activation of CXCL10/CXCR3 contributes to CVA2 pathogenesis via inducing apoptosis, proinflammatory cytokine expression, and inflammatory cell infiltration, which can be reversed by αCXCR3 therapy. This study provides new insight into the pathogenesis of HFMD, which has an important guiding significance for the treatment of HFMD.

SARS-CoV-2 Infection and Pancreatic β Cell Failure

Simple Summary

Accumulating evidence suggests that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may have the potential to induce pancreatic β-cell damage, leading to diabetes onset in patients with coronavirus disease 2019 (COVID-19). However, controversial results have been reported among study groups. Here, we provide a comprehensive review of published findings that describe the potential relationship between SARS-CoV-2 infection (COVID-19) and pancreatic β-cell failure, and how this may contribute to the development of diabetes.

Abstract

SARS-CoV-2 infection primarily causes pulmonary symptoms; however, accumulating reports indicate that some patients with COVID-19 have multiple organ dysfunction or failure. Although diabetes is considered a risk factor for severe COVID-19, SARS-CoV-2 infection may also be a causal factor for diabetes mellitus in patients with COVID-19. According to the research reviewed in this paper, the pancreas and pancreatic β cells appear to be targets of SARS-CoV-2 and are damaged by direct or indirect effects of the infection. However, controversial results have been reported between study groups, mainly due to the limited number of cases with diabetes precipitated by COVID-19. In this review, we comprehensively discuss the published findings on the potential association between SARS-CoV-2 infection or COVID-19 and pancreatic β-cell damage leading to diabetes onset. These findings will further contribute to our understanding of the pathogenesis of diabetes mellitus.

Immunohistochemical detection of enteroviruses in pancreatic tissues of patients with type 1 diabetes using a polyclonal antibody against 2A protease of Coxsackievirus

INTRODUCTION

The need for antiserum for immunohistochemical detection (IHC) of enterovirus (EV) in formaldehyde fixed and paraffin-embedded (FFPE) samples is increasing. The gold standard monoclonal antibody (clone 5D8/1) against EV-envelope protein (VP1) was proven to cross-react with other proteins. Another candidate marker of EV proteins is 2A protease (2A^pro ), which is encoded by EV gene and translated by the host cells during EV replication and participates processing proproteins to viral capsid proteins.

MATERIALS AND METHODS

We raised polyclonal antiserum by immunizing a rabbit with an 18-mer peptide of Coxsackievirus B1 (CVB1)-2A^pro and examined the specificity and sensitivity for EV on FFPE tissue samples.

RESULTS

ELISA study showed a high titer of antibody for 18-mer peptide of CVB1-2A^pro , cross reacting with CVB3-2A^pro peptide. IHC demonstrated that antiserum against 2A^pro reacted with CVB1-infected and VP1-positive Vero-cells. Confocal laser scanning microscopy demonstrated that antigen stained by the 2A^pro antibody located in the same cell with VP1 stained by 5D8/1. IHC using 2A^pro antiserum showed dense staining in the islets of EV-associated fulminant type 1 diabetic pancreas and that located in the same cell stained positive for VP1 (5D8/1). Specificity of 2A^pro antiserum by IHC staining was confirmed by negative 2A^pro in 14 VP1-negative non-diabetic control pancreases.

CONCLUSION

Our study provides a new polyclonal antiserum against CVB1-2A^pro which may be useful for IHC of EV-infected human tissues stored as archive of FFPE tissue samples.

Visceral Adipose Tissue: A New Target Organ in Virus-Induced Type 1 Diabetes

Type 1 diabetes (T1D) is a proinflammatory pathology that leads to the specific destruction of insulin producing β-cells and hyperglycaemia. Much of the knowledge about type 1 diabetes (T1D) has focused on mechanisms of disease progression such as adaptive immune cells and the cytokines that control their function, whereas mechanisms linked with the initiation of the disease remain unknown. It has been hypothesized that in addition to genetics, environmental factors play a pivotal role in triggering β-cell autoimmunity. The BioBreeding Diabetes Resistant (BBDR) and LEW1.WR1 rats have been used to decipher the mechanisms that lead to virus-induced T1D. Both animals develop β-cell inflammation and hyperglycemia upon infection with the parvovirus Kilham Rat Virus (KRV). Our earlier in vitro and in vivo studies indicated that KRV-induced innate immune upregulation early in the disease course plays a causal role in triggering β-cell inflammation and destruction. Furthermore, we recently found for the first time that infection with KRV induces inflammation in visceral adipose tissue (VAT) detectable as early as day 1 post-infection prior to insulitis and hyperglycemia. The proinflammatory response in VAT is associated with macrophage recruitment, proinflammatory cytokine and chemokine upregulation, endoplasmic reticulum (ER) and oxidative stress responses, apoptosis, and downregulation of adipokines and molecules that mediate insulin signaling. Downregulation of inflammation suppresses VAT inflammation and T1D development. These observations are strikingly reminiscent of data from obesity and type 2 diabetes (T2D) in which VAT inflammation is believed to play a causal role in disease mechanisms. We propose that VAT inflammation and dysfunction may be linked with the mechanism of T1D progression.

Natural Killer Cells as Key Mediators in Type I Diabetes Immunopathology

The immunopathology of type I diabetes (T1D) presents a complicated case in part because of the multifactorial origin of this disease. Typically, T1D is thought to occur as a result of autoimmunity toward islets of Langerhans, resulting in the destruction of insulin-producing cells (β cells) and thus lifelong reliance on exogenous insulin. However, that explanation obscures much of the underlying mechanism, and the actual precipitating events along with the associated actors (latent viral infection, diverse immune cell types and their roles) are not completely understood. Notably, there is a malfunctioning in the regulation of cytotoxic CD8+ T cells that target endocrine cells through antigen-mediated attack. Further examination has revealed the likelihood of an imbalance in distinct subpopulations of tolerogenic and cytotoxic natural killer (NK) cells that may be the catalyst of adaptive immune system malfunction. The contributions of components outside the immune system, including environmental factors such as chronic viral infection also need more consideration, and much of the recent literature investigating the origins of this disease have focused on these factors. In this review, the details of the immunopathology of T1D regarding NK cell disfunction is discussed, along with how those mechanisms stand within the context of general autoimmune disorders. Finally, the rarer cases of latent autoimmune, COVID-19 (viral), and immune checkpoint inhibitor (ICI) induced diabetes are discussed as their exceptional pathology offers insight into the evolution of the disease as a whole.

The Fatty Acid Lipid Metabolism Nexus in COVID-19

Enteric symptomology seen in early-stage severe acute respiratory syndrome (SARS)-2003 and COVID-19 is evidence of virus replication occurring in the intestine, liver and pancreas. Aberrant lipid metabolism in morbidly obese individuals adversely affects the COVID-19 immune response and increases disease severity. Such observations are in line with the importance of lipid metabolism in COVID-19, and point to the gut as a site for intervention as well as a therapeutic target in treating the disease. Formation of complex lipid membranes and palmitoylation of coronavirus proteins are essential during viral replication and assembly. Inhibition of fatty acid synthase (FASN) and restoration of lipid catabolism by activation of AMP-activated protein kinase (AMPK) impede replication of coronaviruses closely related to SARS-coronavirus-2 (CoV-2). In vitro findings and clinical data reveal that the FASN inhibitor, orlistat, and the AMPK activator, metformin, may inhibit coronavirus replication and reduce systemic inflammation to restore immune homeostasis. Such observations, along with the known mechanisms of action for these types of drugs, suggest that targeting fatty acid lipid metabolism could directly inhibit virus replication while positively impacting the patient's response to COVID-19.

Fulminant type 1 diabetes: recent research progress and future prospects

To clarify the clinical and etiological characteristics of fulminant type 1 diabetes, we reviewed data from patients who had developed type 1 diabetes following anti-programmed cell death 1/programmed cell death ligand 1 (anti-PD-1/PD-L1) therapy, and research on pancreatic beta cells derived from induced pluripotent stem (iPS) cells from patients with fulminant type 1 diabetes. As determined from the disease classifications and clinical and genetic characteristics, anti-PD-1/PD-L1 therapy-related type 1 diabetes includes both fulminant type 1 diabetes and acute-onset type 1 diabetes. Using insulin-positive cells derived from iPS cells, beta-cell fragility to inflammatory cytokines, but not its regeneration failure, was observed in fulminant type 1 diabetes. Moreover, severe hyperglycemia was reported as a risk factor of sudden death or cardiac arrest at disease onset, diffusion-weighted magnetic resonance imaging was suggested as an additional tool for making a diagnosis, and the CSAD/lnc-ITGB7-1 locus was genetically associated with fulminant type 1 diabetes. To fully understand fulminant type 1 diabetes, it is important to clarify the molecular mechanisms step by step through multifaceted approaches such as through analyses of the genetic factors, clinical features, histological findings, and cell biology. The careful and detailed study of patients is a great means for clarifying the etiology and pathophysiology of the disease.

Fulminant type 1 diabetes: 20 years of discovery and development

Twenty years have passed since the first article on fulminant type 1 diabetes (FT1D) was published. FT1D is characterized by an extremely rapid onset of ketoacidosis, high plasma glucose and, conversely, a near-normal glycosylated hemoglobin level. Digestive or flu-like symptoms frequently precede the onset of ketoacidosis. Patients are usually negative for islet-related autoantibodies, with near-complete destruction of pancreatic β-cells, even at the onset of disease. Massive infiltration of immunocytes (insulitis) can be seen in the islets of patients with new-onset FT1D, but this subsides within a few weeks. Early discovery and development of research on FT1D were carried out in Japan, with some reports from Korea and China. Recently, the recognition of FT1D as an immune-related adverse effect of immune-checkpoint inhibitor therapy for various malignant tumors in some patients has drawn the attention of Western countries. The discovery and successful establishment of FT1D as a disease entity was the product of three essential factors: (1) accumulated research data spanning more than 10 years; (2) fortuitous clinical observation; and (3) organization of a dedicated Japanese research committee. We anticipate that continued investigations of FT1D by a new generation of researchers will further elucidate the pathogenesis and yield new therapies.

Integrative Analyses of Genes Associated with Fulminant Type 1 Diabetes

Objective

Fulminant type 1 diabetes (FT1D) is a type of type 1 diabetes, which is characterized by rapid onset of disease and severe metabolic disorders. We intend to screen for crucial genes and potential molecular mechanisms in FT1D in this study.

Method

We downloaded GSE44314, which includes six healthy controls and five patients with FT1D, from the GEO database. Identification of differentially expressed genes (DEGs) was performed by NetworkAnalyst. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of DEGs were screened by an online tool-Database for Annotation, Visualization, and Integration Discovery (DAVID). Protein-protein interaction (PPI) network and hub genes among DEGs were analyzed by NetworkAnalyst. And we also use NetworkAnalyst to find out the microRNAs (miRNAs) and transcription factors (TFs) which regulate the expression of DEGs.

Result

We identified 130 DEGs (60 upregulated and 70 downregulated DEGs) between healthy controls and FT1D patients. GO analysis results revealed that DEGs were mostly enriched in generation of precursor metabolites and energy, neurohypophyseal hormone activity, and mitochondrial inner membrane. KEGG pathway analysis demonstrated that DEGs were mostly involved in nonalcoholic fatty liver disease. Results indicated that NCOA1, SRF, ERBB3, EST1, TOP1, UBE2S, INO80, COX7C, ITGAV, and COX6C were the top hub genes in the PPI network. Furthermore, we recognized that LDLR, POTEM, IFNAR2, BAZ2A, and SRF were the top hub genes in the miRNA-target gene network, and SRF, TSPAN4, CD59, ETS1, and SLC25A25 were the top hub genes in the TF-target gene network.

Conclusion

Our study pinpoints key genes and pathways associated with FT1D by a sequence of bioinformatics analysis on DEGs. These identified genes and pathways provide more detailed molecular mechanisms of FT1D and may provide novel therapeutic targets.

Enteroviruses and Type 1 Diabetes Mellitus: An Overlooked Relationship in Some Regions

Enteroviruses (EVs) infect millions of people annually. EV infections can be asymptomatic or symptomatic with conditions ranging from mild illnesses to serious diseases such as dilated cardiomyopathy. A causal relationship between EV infections and type 1 diabetes mellitus (T1DM) has been heavily debated, with some studies suggesting that this relationship is not yet conclusive and requires additional evidence, whereas others strongly argue for this correlation. While this relationship is well investigated in some developed countries like the USA and Finland, it is understudied or neglected in other countries like Russia for many reasons such as the low incidence of T1DM. Although the Middle East and North Africa (MENA) are highly affected by T1DM, the role of EVs in the disease in MENA has not been investigated extensively. Therefore, we aimed to address the relationship between T1DM and EVs in MENA and other regions globally.

Fulminant type 1 diabetes: A comprehensive review of an autoimmune condition

Fulminant type 1 diabetes (FT1D) is a subset of type 1 diabetes characterized by extremely rapid pancreatic β-cell destruction with aggressive progression of hyperglycaemia and ketoacidosis. It was initially classified as idiopathic type 1 diabetes due to the absence of autoimmune markers. However, subsequent studies provide evidences supporting the involvement of autoimmunity in rapid β-cell loss in FT1D pathogenesis, which are crucial for FT1D being an autoimmune disease. This article highlights the role of immunological aspects in FT1D according to the autoimmune-associated genetic background, viral infection, innate immunity, adaptive immunity, and pancreas histology.

Unique pathological changes in the pancreas of fulminant type 1 diabetes

Distinct features of the pancreas of fulminant type 1 diabetes (FT1DM) include (1) enterovirus infection of the islets and exocrine acinar tissue. (2) Activated innate immune responses: MDA5 and RIG-I expression and TLR4 and TLR9 expression in the islets of FT1DM. (3) Combined activation of the STAT/JNK and NFkB pathways, resulting in Type I interferon (IFN) and proinflammatory cytokine (i.e., IFNγ) expression in islet beta cells and MHC class I hyper-expression. (4) Activation of dendritic cells followed by effector cell infiltration of CD8⁺ T cells and CD68⁺ macrophages, resulting in apoptosis and neurosis of islet cells and exocrine acinar cells. (5) Many chemo-attractants (i.e., CXCL10) and chemotactic activators (i.e., l-plastin) were induced by a viral infection. (6) Mutual stimulating effect of cytokines expressed in beta cells in autocrine and paracrine mechanisms may enhance beta-cell destruction through the STA1-caspase pathway. (7) Proteomics analysis using laser capture microdissection followed by mass spectrometry found 38 molecules in inflamed islets of FT1DM, which were not highlighted before. Our pathologically verified model of beta-cell destruction in FT1DM will contribute to anti-virus therapy of type 1 diabetes in the near future.

Genetic Susceptibility of the Host in Virus-Induced Diabetes

Enteroviruses, especially Coxsackie B viruses, are among the candidate environmental factors causative of type 1 diabetes. Host genetic factors have an impact on the development of virus-induced diabetes (VID). Host background, in terms of whether the host is prone to autoimmunity, should also be considered when analyzing the role of target genes in VID. In this review, we describe the genetic susceptibility of the host based on studies in humans and VID animal models. Understanding the host genetic factors should contribute not only to revealing the mechanisms of VID development, but also in taking measures to prevent VID.

Innate Viral Sensor MDA5 and Coxsackievirus Interplay in Type 1 Diabetes Development

Type 1 diabetes (T1D) is a polygenic autoimmune disease characterized by immune-mediated destruction of insulin-producing β-cells. The concordance rate for T1D in monozygotic twins is ≈30-50%, indicating that environmental factors also play a role in T1D development. Previous studies have demonstrated that enterovirus infections such as coxsackievirus type B (CVB) are associated with triggering T1D. Prior to autoantibody development in T1D, viral RNA and antibodies against CVB can be detected within the blood, stool, and pancreata. An innate pathogen recognition receptor, melanoma differentiation-associated protein 5 (MDA5), which is encoded by the IFIH1 gene, has been associated with T1D onset. It is unclear how single nucleotide polymorphisms in IFIH1 alter the structure and function of MDA5 that may lead to exacerbated antiviral responses contributing to increased T1D-susceptibility. Binding of viral dsRNA via MDA5 induces synthesis of antiviral proteins such as interferon-alpha and -beta (IFN-α/β). Viral infection and subsequent IFN-α/β synthesis can lead to ER stress within insulin-producing β-cells causing neo-epitope generation, activation of β-cell-specific autoreactive T cells, and β-cell destruction. Therefore, an interplay between genetics, enteroviral infections, and antiviral responses may be critical for T1D development.

Impaired upregulation of Stat2 gene restrictive to pancreatic β-cells is responsible for virus-induced diabetes in DBA/2 mice

Viral infection is a putative causal factor for the development of type 1 diabetes, but the exact pathogenic mechanism of virus-induced diabetes (VID) remains unclear. Here, to identify the critical factors that regulate VID, we analyzed encephalomyocarditis D (EMC-D) VID-sensitive DBA/2 mice in comparison with resistant B6 mice. EMC-D virus-induced cell death occurred more frequently in DBA/2 β-cells than in B6 β-cells with 100U/ml IFN-β priming in vitro. We therefore purified β-cells using flow cytometry from mice two days after EMC-D virus infection and subjected them to microarray analysis. As a results, innate immune response pathway was found to be enriched in B6 β-cells. The signal transducer and activator of transcription 2 (Stat2) gene interacted with genes in the pathway. Stat2 gene expression levels were lower in DBA/2 mice than in B6 mice, restrictive to β-cells. Moreover, administration of IFN-β failed to upregulate Stat2 gene in DBA/2 β-cells than in those of B6 in vivo. The viral titer significantly increased only in the DBA/2 pancreas. Thus, these provided data suggest that impaired upregulation of Stat2 gene restrictive to β-cells at the early stage of infection is responsible for VID development in DBA/2 mice.

Pancreatic Alpha-Cells Contribute Together With Beta-Cells to CXCL10 Expression in Type 1 Diabetes

C-X-C Motif Chemokine Ligand 10 (CXCL10) is a pro-inflammatory chemokine specifically recognized by the ligand receptor CXCR3 which is mostly expressed in T-lymphocytes. Although CXCL10 expression and secretion have been widely associated to pancreatic islets both in non-obese diabetic (NOD) mice and in human type 1 diabetic (T1D) donors, the specific expression pattern among pancreatic endocrine cell subtypes has not been clarified yet. Therefore, the purpose of this study was to shed light on the pancreatic islet expression of CXCL10 in NOD, in C57Bl/6J and in NOD-SCID mice as well as in human T1D pancreata from new-onset T1D patients (DiViD study) compared to non-diabetic multiorgan donors from the INNODIA European Network for Pancreatic Organ Donors with Diabetes (EUnPOD). CXCL10 was expressed in pancreatic islets of normoglycaemic and new-onset diabetic NOD mice but not in C57Bl/6J and NOD-SCID mice. CXCL10 expression was increased in pancreatic islets of new-onset diabetic NOD mice compared to normoglycaemic NOD mice. In NOD mice, CXCL10 colocalized both with insulin and glucagon. Interestingly, CXCL10-glucagon colocalization rate was significantly increased in diabetic vs. normoglycaemic NOD mouse islets, indicating an increased expression of CXCL10 also in alpha-cells. CXCL10 was expressed in pancreatic islets of T1D patients but not in non-diabetic donors. The analysis of the expression pattern of CXCL10 in human T1D pancreata from DiViD study, revealed an increased colocalization rate with glucagon compared to insulin. Of note, CXCL10 was also expressed in alpha-cells residing in insulin-deficient islets (IDI), suggesting that CXCL10 expression in alpha cells is not driven by residual beta-cells and therefore may represent an independent phenomenon. In conclusion, we show that in T1D CXCL10 is expressed by alpha-cells both in NOD mice and in T1D patients, thus pointing to an additional novel role for alpha-cells in T1D pathogenesis and progression.

Chemokines as Drivers of the Autoimmune Destruction in Type 1 Diabetes: Opportunity for Therapeutic Intervention in Consideration of an Optimal Treatment Schedule

Type 1 diabetes (T1D) is mainly precipitated by the destruction of insulin-producing β-cells in the pancreatic islets of Langerhans by autoaggressive T cells. The etiology of the disease is still not clear, but besides genetic predisposition the exposure to environmental triggers seems to play a major role. Virus infection of islets has been demonstrated in biopsies of T1D patients, but there is still no firm proof that such an infection indeed results in islet-specific autoimmunity. However, virus infection results in a local inflammation with expression of inflammatory factors, such as cytokines and chemokines that attract and activate immune cells, including potential autoreactive T cells. Many chemokines have been found to be elevated in the serum and expressed by islet cells of T1D patients. In mouse models, it has been demonstrated that β-cells express chemokines involved in the initial recruitment of immune cells to the islets. The bulk load of chemokines is however released by the infiltrating immune cells that also express multiple chemokine receptors. The result is a mutual attraction of antigen-presenting cells and effector immune cells in the local islet microenvironment. Although there is a considerable redundancy within the chemokine ligand-receptor network, a few chemokines, such as CXCL10, seem to play a key role in the T1D pathogenesis. Studies with neutralizing antibodies and investigations in chemokine-deficient mice demonstrated that interfering with certain chemokine ligand-receptor axes might also ameliorate human T1D. However, one important aspect of such a treatment is the time of administration. Blockade of the recruitment of immune cells to the site of autoimmune destruction might not be effective when the disease process is already ongoing. By that time, autoaggressive cells have already arrived in the islet microenvironment and a blockade of migration might even hold them in place leading to accelerated destruction. Thus, an anti-chemokine therapy makes most sense in situations where the cells have not yet migrated to the islets. Such situations include treatment of patients at risk already carrying islet-antigen autoantibodies but are not yet diabetic, islet transplantation recipients, and patients that have undergone a T cell reset as occurring after anti-CD3 antibody treatment.

Unique Inflammatory Changes in Exocrine and Endocrine Pancreas in Enterovirus-Induced Fulminant Type 1 Diabetes

CONTEXT

There are scant reports on the pathological changes of the exocrine and endocrine pancreas in fulminant type 1 diabetes mellitus (FT1DM).

OBJECTIVE

To clarify the distinct pathological changes in the exocrine as well as the endocrine pancreas shortly after onset of diabetes in FT1DM.

DESIGN

The exocrine and endocrine pancreases of 3 patients with FT1DM and 17 nondiabetic controls were immunohistochemically examined for islet and exocrine tissue inflammation, infiltrating mononuclear cell (MNC) CD subtype, enterovirus capsid protein 1 (VP1) localization, and CXC chemokine ligand 10 (CXCL10) and CXC chemokine receptor 3 (CXCR3) expressions.

RESULTS

The median frequency of insulitis in the 3 FT1DM pancreases was 60%. In the nondiabetic control pancreases, no insulitis was observed. In the islets of FT1DM, the numbers of CD45+, CD3+, CD8+, CD68+, and CD11c+ MNCs were significantly higher than those of the control group. In the exocrine pancreas of FT1DM, the numbers of CD3+ T cells, CD8+ T cells, CD68+ macrophages, and CD11c+ dendritic cells were significantly higher than those of the control group. Infiltrating CD8+ T cells, CD68+ macrophages, and CD11c+ dendritic cells were observed around exocrine acinar cells in FT1DM. There was a close association between VP1 and CXCL10 expression in pancreatic exocrine ductal cells and acinar cells as well as islet cells in FT1DM. CXCL10+ exocrine cells were surrounded by CXCR3+ T cells.

CONCLUSION

The pathological findings suggested that suppression of the activated CXCL10-CXCR3 axis in the exocrine as well as the endocrine pancreas is a novel therapeutic target in FT1DM and possibly in enterovirus-associated acute-onset type 1 diabetes.

Pathogenesis of fulminant type 1 diabetes: Genes, viruses and the immune mechanism, and usefulness of patient-derived induced pluripotent stem cells for future research

We reviewed fulminant type 1 diabetes, a recently established subtype of type 1 diabetes, from the aspects of genes, viruses, immune mechanism and usefulness of patient-derived induced pluripotent stem cells (iPSCs). In an analysis of the pancreas of patients with fulminant type 1 diabetes, viral antigens and viral receptors were expressed in β-cells, as well as macrophages and T lymphocytes surrounding the β-cells. These findings suggest that the β-cells of patients with fulminant type 1 diabetes are destroyed during an immune response against viral infection of the pancreas. Recently, fulminant type 1 diabetes was induced by treatment with anti-programmed cell death 1 antibodies, suggesting that immune regulatory mechanisms are also involved in the onset of this disease. We generated iPSCs from patients with fulminant type 1 diabetes for the first time. We also successfully differentiated patient-derived iPSCs into insulin-producing cells in vitro, and produced a disease model. The proportion of cytokine-induced apoptotic cells among insulin-positive cells was higher in the iPSCs from patients with fulminant type 1 diabetes than in iPSCs from healthy control participants. We carried out ribonucleic acid sequencing in insulin-producing cells differentiated from patient-derived iPSCs, and are now attempting to identify new biomarkers for the disease.

Impact of coxsackievirus-B4E2 combined with a single low dose of streptozotocin on pancreas of outbred mice: investigation of viral load, pathology and inflammation

Coxsackieviruses B (CV-B) belong to the EV-B species. CV-B and particularly CV-B4 are thought to be involved in the development of chronic diseases like type 1 diabetes (T1D). The mechanisms of the enteroviral pathogenesis of T1D are not well known, yet. The in vitro studies are rich with information but in vivo infection models are needed to investigate the impact of viruses onto organs. Our objective was to study the impact of CV-B4E2 combined with a single sub-diabetogenic dose of streptozotocin (STZ) on the pancreas of mice. The infection with CV-B4E2 of CD1 outbred mice treated with a sub-diabetogenic dose of STZ induced hyperglycemia and hypoinsulinemia. Along with the chemokine IP-10, viral RNA and infectious particles were detected in the pancreas. The pancreas of these animals was also marked with insulitis and other histological alterations. The model combining STZ and CV-B4E2 opens the door to new perspectives to better understand the interactions between virus and host, and the role of environmental factors capable, like STZ, to predispose the host to the diabetogenic effects of enteroviruses.

Clinical characteristics of anti-glutamic acid decarboxylase antibody-positive fulminant type 1 diabetes

This research aimed to examine the relationship between anti-glutamic acid decarboxylase antibody (GADA) titers and clinical parameters at onset and to clarify the association between clinical severity and GADA titers in GADA-positive fulminant type 1 diabetes. This cross-sectional observational study included 20 cases with GADA-positive fulminant type 1 diabetes (4 cases from our hospital and 16 from cases reported in the literature). The association between GADA titers and clinical parameters [age, sex, body weight, body mass index, period from appearance of any prodromal symptoms to diagnosis, period from development of hyperglycemic symptoms to diagnosis, GADA titer, HbA1c level, blood pH and HCO₃^- level, serum levels of ketone bodies and pancreatic exocrine enzymes] were analyzed. Spearman's rank correlation coefficient (r_s) was used for the correlation analysis. The results showed that there was a significant inverse correlation between GADA titers and the "period from appearance of any prodromal symptoms to diagnosis" (r_s = -0.559, p < 0.05). Moreover, GADA titers were inversely correlated with blood pH and HCO₃^- level (r_s = -0.576, p < 0.05, r_s = -0.578, p < 0.05, respectively), and positively correlated with serum levels of total ketone bodies, acetoacetate, and 3-hydroxybutyrate (r_s = 0.661, p < 0.05; r_s = 0.700, p < 0.05; and r_s = 0.782, p < 0.01, respectively). These findings suggest that higher GADA titers may be linked to more severe clinical severity of GADA-positive fulminant type 1 diabetes at onset. This association may be attributed to possible pre-existence of autoimmunity-related β-cell damage before the onset of fulminant type 1 diabetes.

Epigenetic modulation of β cells by interferon-α via PNPT1/mir-26a/TET2 triggers autoimmune diabetes

Type 1 diabetes (T1D) is caused by autoimmune destruction of pancreatic β cells. Mounting evidence supports a central role for β cell alterations in triggering the activation of self-reactive T cells in T1D. However, the early deleterious events that occur in β cells, underpinning islet autoimmunity, are not known. We hypothesized that epigenetic modifications induced in β cells by inflammatory mediators play a key role in initiating the autoimmune response. We analyzed DNA methylation (DNAm) patterns and gene expression in human islets exposed to IFN-α, a cytokine associated with T1D development. We found that IFN-α triggers DNA demethylation and increases expression of genes controlling inflammatory and immune pathways. We then demonstrated that DNA demethylation was caused by upregulation of the exoribonuclease, PNPase old-35 (PNPT1), which caused degradation of miR-26a. This in turn promoted the upregulation of ten-eleven translocation 2 (TET2) enzyme and increased 5-hydroxymethylcytosine levels in human islets and pancreatic β cells. Moreover, we showed that specific IFN-α expression in the β cells of IFNα-INS1CreERT2 transgenic mice led to development of T1D that was preceded by increased islet DNA hydroxymethylation through a PNPT1/TET2-dependent mechanism. Our results suggest a new mechanism through which IFN-α regulates DNAm in β cells, leading to changes in expression of genes in inflammatory and immune pathways that can initiate islet autoimmunity in T1D.

Genome-Wide Association Study Confirming a Strong Effect of HLA and Identifying Variants in CSAD/lnc-ITGB7-1 on Chromosome 12q13.13 Associated With Susceptibility to Fulminant Type 1 Diabetes

The first genome-wide association study of fulminant type 1 diabetes was performed in Japanese individuals. As previously reported using a candidate gene approach, a strong association was observed with multiple single nucleotide polymorphisms (SNPs) in the HLA region, and the strongest association was observed with rs9268853 in the class II DR region (P = 1.56 × 10^-23, odds ratio [OR] 3.18). In addition, rs11170445 in CSAD/lnc-ITGB7-1 on chromosome 12q13.13 showed an association at a genome-wide significance level (P = 7.58 × 10^-9, OR 1.96). Fine mapping of the region revealed that rs3782151 in CSAD/lnc-ITGB7-1 showed the lowest P value (P = 4.60 × 10^-9, OR 1.97 [95% CI 1.57-2.48]). The risk allele of rs3782151 is a cis expression quantitative trait locus for ITGB7 that significantly increases the expression of this gene. CSAD/lnc-ITGB7-1 was found to be strongly associated with susceptibility to fulminant, but not classical, autoimmune type 1 diabetes, implicating this locus in the distinct phenotype of fulminant type 1 diabetes.

The characteristics of blood glucose fluctuations in patients with fulminant type 1 diabetes mellitus in the stable stage

OBJECTIVE

The aim was to characterize blood glucose fluctuations in patients with fulminant type 1 diabetes (FT1DM) at the stable stage using continuous blood glucose monitoring systems (CGMSs).

SUBJECTS AND METHODS

Ten patients with FT1DM and 20 patients with classic type 1 diabetes mellitus (T1DM) (the control group) were monitored using CGMSs for 72 hours.

RESULTS

The CGMS data showed that the mean blood glucose (MBG), the standard deviation of the blood glucose (SDBG), the mean amplitude glycemic excursions (MAGE), the blood glucose areas and the percentages of blood glucose levels below 13.9 mmol/L were similar between the two groups. However, the percentage of blood glucose levels below 3.9 mmol/L was significantly higher in the FT1DM group compared to the T1DM group (p < 0.05). The minimum (Min) blood glucose level in the FT1DM group was significantly lower than that of the T1DM group (p < 0.05). Patients with FT1DM had severe dysfunction of the islet beta cells and alpha cells compared to patients with T1DM, as indicated by lower C-peptide values and higher glucagon/C-peptide values.

CONCLUSION

In conclusion, patients with FT1DM at the stable stage were more prone to hypoglycemic episodes as recorded by CGMSs, and they had a greater association with severe dysfunction of both the beta and alpha islet cells compared to patients with T1DM.

Fulminant type 1 diabetes mellitus: Two case reports

RATIONALE

Fulminant type 1 diabetes mellitus (FT1DM) is a new subtype of type 1 diabetes mellitus that was first proposed by the Japanese scholar Imagawa in 2000. In the 2 patient cases described in this study, gastrointestinal symptoms were the first symptoms reported, and the initial blood glucose levels were very high. However, the glycosylated hemoglobin (HbA1c) levels were not very high, the islet β-cell function was almost completely lost in a short time, and the metabolic disorder was severe; the patients' islet β cells demonstrated complete and irreversible functional damage, and the prognosis was poor.

PATIENT CONCERNS

We report a 37-year-old and 48-year-old male patients. The first patient was addmited with emesis and diarrhea for 2 days and the second patient had stomachache for 8 days, emesis and dyspnea for half an hour before admission. Both patients had no history of hypertension, coronary heart disease, or hyperglycemia.

DIAGNOSIS

Two patients had same scenario: acute onset, hyperglycemia, ketoacidosis, β cell function deficiency, and HbA1c <8.5%.

INTERVENTIONS

After admission, the administration of adequate liquid infusion, the intravenous injection of regular insulin to reduce the blood glucose levels, and the correction of electrolyte disturbance and acid-base imbalance were conducted.

OUTCOMES

Subsequently, the blood glucose level of the patients was gradually reduced, the acidosis was corrected, and the disease conditions gradually stabilized. For both patients, the long-term insulin replacement therapy of "insulin aspart plus insulin glargine" was selected.

LESSONS

FT1DM is a new subtype of type 1 diabetes mellitus. The onset of this disease is rapid, and the function of islet β cells is almost completely lost in a short time period. This metabolic disorder is severe, and the clinical manifestations are nonspecific. Unless a timely and accurate diagnosis is made, and patients receive prompt treatment, it is difficult to control the disease and the risk of death is high.

Memory-like Liver Natural Killer Cells are Responsible for Islet Destruction in Secondary Islet Transplantation

We previously demonstrated the pivotal role of natural killer (NK) cells in islet graft loss during the early phase after intraportal syngeneic islet transplantation (IT). Liver-resident DX5^- NK cells were reported to possess memory-like properties, distinguishing them from conventional DX5⁺ NK cells. Here, we investigated the impact of primary IT-induced liver DX5^- NK cells on the engraftment of secondary-transplanted islets in mice. The culture of liver NK cells isolated from naive mice with TNF-α, IFN-γ, and IL-lβ, mimicking instant blood-mediated inflammatory reaction, led to significantly increased DX5^- NK cell percentage among total liver NK cells. Consistently, the prolonged expansion of DX5^- CD69⁺ TRAIL⁺ CXCR3⁺ NK cells was observed after intraportal IT of 300 syngeneic islets (marginal mass). In most diabetic mice, 400 syngeneic islets of primary IT were sufficient to achieve normoglycaemia, whereas the same mass after secondary IT failed to induce normoglycaemia in mice that received 200 syngeneic islets during primary IT. These findings indicated that liver-resident DX5^- NK cells significantly expanded even after syngeneic IT, and that these memory-like NK cells may target both originally engrafted and secondary-transplanted islets. Furthermore, anti-TNF-α treatment suppressed the expansion of liver-resident DX5^- NK cells, resulting in successful islet engraftment after sequential ITs.

FOXP3+ Regulatory T Cell Compartment Is Altered in Children With Newly Diagnosed Type 1 Diabetes but Not in Autoantibody-Positive at-Risk Children

The dysfunction of FOXP3-positive regulatory T cells (Tregs) plays a key role in the pathogenesis of autoimmune diseases, including type 1 diabetes (T1D). However, previous studies analyzing the peripheral blood Treg compartment in patients with T1D have yielded partially conflicting results. Moreover, the phenotypic complexity of peripheral blood Tregs during the development of human T1D has not been comprehensively analyzed. Here, we used multi-color flow cytometry to analyze the frequency of distinct Treg subsets in blood samples from a large cohort comprising of 74 children with newly diagnosed T1D, 76 autoantibody-positive children at-risk for T1D and 180 age- and HLA-matched control children. The frequency of CD4+CD25+CD127lowFOXP3+ Tregs was higher in children with T1D compared to control children, and this change was attributable to a higher proportion of naïve Tregs in these subjects. Further longitudinal analyses demonstrated that the increase in Treg frequency correlated with disease onset. The frequencies of the minor subsets of CD25+FOXP3low memory Tregs as well as CD25lowCD127lowFOXP3+ Tregs were also increased in children with T1D. Moreover, the ratio of CCR6-CXCR3+ and CCR6+CXCR3- memory Tregs was altered and the frequency of proliferating Ki67-positive and IFN-γ producing memory Tregs was decreased in children with T1D. The frequency of CXCR5+FOXP3+ circulating follicular T regulatory cells was not altered in children with T1D. Importantly, none of the alterations observed in children with T1D were observed in autoantibody-positive at-risk children. In conclusion, our study reveals multiple alterations in the peripheral blood Treg compartment at the diagnosis of T1D that appear not to be features of early islet autoimmunity.

Diffusion-weighted magnetic resonance imaging in the pancreas of fulminant type 1 diabetes

Abrupt disease onset and severe metabolic disorders are main characteristics of fulminant type 1 diabetes. Diffusion-weighted magnetic resonance imaging (DWI) is an imaging technique that reflects restricted diffusion in organs and can detect mononuclear cell infiltration into the pancreas at the onset of the disease. Fourteen patients with fulminant type 1 diabetes who underwent abdominal magnetic resonance imaging were recruited for the measurement of apparent diffusion coefficient (ADC) values of the pancreas that were compared with those of 21 non-diabetic controls. The ADC values of all parts of the pancreas were significantly lower in fulminant type 1 diabetes than in controls (head, 1.424 ± 0.382 × 10^-3 vs. 1.675 ± 0.227 × 10^-3 mm²/s; body, 1.399 ± 0.317 × 10^-3 vs. 1.667 ± 0.170 × 10^-3 mm²/s; tail, 1.336 ± 0.247 × 10^-3 vs. 1.561 ± 0.191 × 10^-3 mm²/s; mean, 1.386 ± 0.309 × 10^-3 vs. 1.634 ± 0.175 × 10^-3 mm²/s) (p < 0.01). The best cut-off value indicated that the sensitivity was 86% and the specificity was 71% when using DWI, which was also efficient in two atypical patients with fulminant type 1 diabetes without elevated levels of exocrine pancreatic enzymes or with high HbA1c levels due to the preexistence of type 2 diabetes. The ADC values were significantly correlated to plasma glucose levels and arterial pH, and tended to increase with the lapse of time. DWI may be an additional tool for making an efficient diagnosis of fulminant type 1 diabetes.

The Immunobiology of Receptor Activator for Nuclear Factor Kappa B Ligand and Myeloid-Derived Suppressor Cell Activation in Immunoglobulin G4-Related Sclerosing Cholangitis

The primary function of myeloid-derived suppressor cells (MDSCs) is reflected in their immune modulatory role in several immune-mediated diseases. In immunoglobulin G4 (IgG4)-related disease (IgG4-RD), it has been hypothesized that there are selective regulatory defects that lead to a T helper 2 (Th2) bias immune response. Herein we have taken advantage of a large cohort of patients with IgG4-related sclerosing cholangitis (IgG4-SC), the most common extrapancreatic involvement of IgG4-RD, as well as controls consisting of primary sclerosing cholangitis, autoimmune hepatitis, and healthy volunteers, to study MDSCs. We report dramatically increased levels of receptor activator for nuclear factor kappa B ligand (RANKL) expression in serum and liver from patients with IgG4-SC compared to both liver-disease and healthy controls. Moreover, in IgG4-SC liver, RANKL-secreting cells specifically colocalized with cluster of differentiation 38-positive plasma cells and MDSCs, particularly monocytic MDSCs, and express the RANKL receptor in liver. Similarly, the frequency and number of peripheral blood MDSCs were significantly increased. Importantly, serum expression levels of RANKL were inversely correlated with the serum level of gamma-glutamyltransferase but significantly positively correlated with the frequency of MDSCs. Moreover, we confirmed that RANKL induced the expansion and activation of MDSCs through the RANKL/RANK/nuclear factor kappa B signal pathway. Of note, RANKL-treated MDSCs suppressed T-cell proliferation and induced Th2 differentiation. Conclusion: Our data suggest that plasma cell-derived RANKL induces the expansion and activation of MDSCs, which suppress T-cell proliferation and contribute to the Th2-type response characteristic of IgG4-SC.

Distinct Inflammatory Changes of the Pancreas of Slowly Progressive Insulin-dependent (Type 1) Diabetes

OBJECTIVE

The aim of this study was to identify the distinct pathological changes on the endocrine and exocrine pancreas of slowly progressive insulin-dependent diabetes mellitus (SPIDDM) or latent autoimmune diabetes in adults.

METHODS

The pancreases from 12 islet autoantibody-positive SPIDDM patients and 19 age-matched subjects with no diabetes were examined histologically for islet inflammation/insulitis, expressions of cytokines, and enterovirus VP1 protein, exocrine pancreatic inflammation, pancreatic ductal changes, major histocompatibility complex class I hyperexpression, and amylin-positive amyloid in the islets.

RESULTS

Insulitis dominant for CD8 T-cells and CD68 macrophages was observed in all SPIDDM cases irrespective of duration of diabetes and weight of residual beta cells. Major histocompatibility complex class I hyperexpression on residual beta cells was observed in SPIDDM. All SPIDDM exocrine pancreases showed extensive inflammation, dilated pancreatic ducts, and periductal fibrosis. As many as 75% (9/12) of pancreases had pancreatic intraepithelial neoplasia, which is assumed to be associated with ductal obstruction/narrowing and exocrine pancreatic inflammation, in SPIDDM. Amylin-positive amyloid deposition was not detected in SPIDDM.

CONCLUSIONS

Persistent insulitis with preserved beta cells and major histocompatibility complex class I hyperexpression and exocrine pancreatic inflammation with pancreatic intraepithelial neoplasia are distinct histological features of SPIDDM pancreas.

Analysis of pancreatic volume in acute-onset, slowly-progressive and fulminant type 1 diabetes in a Japanese population

AIMS/INTRODUCTION

A decrease in the size of the pancreas is observed in islet autoantibody-positive non-diabetic donors and acute-onset type 1 diabetes irrespective of the diabetes duration. Little is known, however, about the relationship between the size of the pancreas and type 1 diabetes subtypes, including fulminant type 1 diabetes.

MATERIALS AND METHODS

We examined the pancreatic volume (PV) in 44 adult patients with type 1 diabetes (16 acute-onset type 1 diabetes, 18 slowly progressive type 1 diabetes and 10 fulminant type 1 diabetes) and 39 age- and body mass index-matched non-diabetic controls. PV was measured by computed tomography. The ability to secrete insulin was assessed by stimulated C-peptide after intravenous glucagon administration.

RESULTS

PV was significantly correlated with bodyweight in both control participants and type 1 diabetes patients. The PV index (PVI; PV/bodyweight) was decreased by 39% in type 1 diabetes compared with that in controls. PVI was significantly decreased in acute-onset type 1 diabetes patients and slowly progressive type 1 diabetes patients (both P < 0.0001), but not in fulminant type 1 diabetes patients (P = 0.10), compared with control participants. In cases patients with recent-onset type 1 diabetes (0-7 days post-diagnosis), PVI was significantly decreased in acute-onset type 1 diabetes patients (n = 8, P = 0.0005), but not in fulminant type 1 diabetes patients (n = 7, P = 0.44), compared with controls. PVI showed no correlations with the diabetes duration, C-peptide levels, glycated hemoglobin, glutamic acid decarboxylase autoantibody levels, serum amylase or daily total insulin dose in type 1 diabetes subtypes.

CONCLUSIONS

The present results show that patients with acute-onset type 1 diabetes and slowly progressive type 1 diabetes have small pancreases irrespective of the diabetes duration or C-peptide levels. In contrast to earlier findings on acute-onset type 1 diabetes, we found no reduction of PVI at the onset of fulminant type 1 diabetes.

Fulminant type 1 diabetes mellitus in Japanese children and adolescents: multi-institutional joint research of the Japanese Study Group of Insulin Therapy for Childhood and Adolescent Diabetes

Fulminant type 1 diabetes mellitus (FT1DM) is a subtype of type 1 diabetes mellitus characterized by a remarkably abrupt onset. In Japan, FT1DM accounts for approximately 20% of acute-onset adult type 1 diabetes mellitus cases; however, reports of pediatric-onset FT1DM are rare. We aimed to determine the frequency and clinical characteristics of FT1DM in Japanese children and adolescents by conducting a 2-phase questionnaire survey among the members of the Japanese Study Group of Insulin Therapy for Childhood and Adolescent Diabetes (JSGIT) regarding their clinical experience with FT1DM. Responses were obtained from 54 of the 79 participating hospitals (68.4%). Of these, 8 hospitals managed a total of 15 pediatric patients with FT1DM (4 patients in each of 2 hospitals, 2 patients in 1 hospital, and 1 patient in each of 5 hospitals). The distribution of patient age was biphasic, with peaks in children younger than 5 years and older than 8 years of age. The clinical characteristics of FT1DM in this population (such as the duration from onset of symptoms to diagnosis, severity of symptoms, preceding flu-like episodes, and abnormal laboratory data) did not differ from those of patients with adult-onset FT1DM. The frequency of pediatric-onset FT1DM is low compared with that of adult-onset FT1DM. The genetic background and susceptibility patterns of pediatric patients with FT1DM may differ from those typical of adults with FT1DM, but both age groups share similar clinical characteristics.

Neonatal hyperglycemia induces CXCL10/CXCR3 signaling and microglial activation and impairs long-term synaptogenesis in the hippocampus and alters behavior in rats

BACKGROUND

Hyperglycemia is common in extremely low gestational age newborns (ELGAN) and is associated with increased mortality and morbidity, including abnormal neurodevelopment. Hippocampus-mediated cognitive deficits are common in this population, but the specific effects of hyperglycemia on the developing hippocampus are not known.

METHODS

The objective of this study was to determine the acute and long-term effects of hyperglycemia on the developing hippocampus in neonatal rats using a streptozotocin (STZ)-induced model of hyperglycemia. STZ was injected on postnatal day (P) 2, and littermates in the control group were injected with an equivalent volume of citrate buffer. The acute effects of hyperglycemia on markers of oxidative stress, inflammatory cytokines, microglial activation, and reactive astrocytosis in the hippocampus were determined in the brain tissue collected on P6. The long-term effects on hippocampus-mediated behavior and hippocampal dendrite structure were determined on P90.

RESULTS

On P6, the transcript and protein expression of markers of oxidative stress and inflammatory cytokines, including the CXCL10/CXCR3 pathway, were upregulated in the hyperglycemia group. Histological evaluation revealed microglial activation and astrocytosis. The long-term assessment on P90 demonstrated abnormal performance in Barnes maze neurobehavioral testing and altered dendrite structure in the hippocampus of formerly hyperglycemic rats.

CONCLUSIONS

Neonatal hyperglycemia induces CXCL10/CXCR3 signaling, microglial activation, and astrocytosis in the rat hippocampus and alters long-term synaptogenesis and behavior. These results may explain the hippocampus-specific cognitive deficits common in ELGAN who experience neonatal hyperglycemia.