Insulitis and β-Cell Mass in the Natural History of Type 1 Diabetes

Untangling the genetics of beta cell dysfunction and death in type 1 diabetes

BACKGROUND

Type 1 diabetes (T1D) is a complex multi-system disease which arises from both environmental and genetic factors, resulting in the destruction of insulin-producing pancreatic beta cells. Over the past two decades, human genetic studies have provided new insight into the etiology of T1D, including an appreciation for the role of beta cells in their own demise.

SCOPE OF REVIEW

Here, we outline models supported by human genetic data for the role of beta cell dysfunction and death in T1D. We highlight the importance of strong evidence linking T1D genetic associations to bona fide candidate genes for mechanistic and therapeutic consideration. To guide rigorous interpretation of genetic associations, we describe molecular profiling approaches, genomic resources, and disease models that may be used to construct variant-to-gene links and to investigate candidate genes and their role in T1D.

MAJOR CONCLUSIONS

We profile advances in understanding the genetic causes of beta cell dysfunction and death at individual T1D risk loci. We discuss how genetic risk prediction models can be used to address disease heterogeneity. Further, we present areas where investment will be critical for the future use of genetics to address open questions in the development of new treatment and prevention strategies for T1D.

Development, regeneration, and physiological expansion of functional β-cells: Cellular sources and regulators

Pancreatic regeneration is a complex process observed in both normal and pathological conditions. The aim of this review is to provide a comprehensive understanding of the emergence of a functionally active population of insulin-secreting β-cells in the adult pancreas. The renewal of β-cells is governed by a multifaceted interaction between cellular sources of genetic and epigenetic factors. Understanding the development and heterogeneity of β-cell populations is crucial for functional β-cell regeneration. The functional mass of pancreatic β-cells increases in situations such as pregnancy and obesity. However, the specific markers of mature β-cell populations and postnatal pancreatic progenitors capable of increasing self-reproduction in these conditions remain to be elucidated. The capacity to regenerate the β-cell population through various pathways, including the proliferation of pre-existing β-cells, β-cell neogenesis, differentiation of β-cells from a population of progenitor cells, and transdifferentiation of non-β-cells into β-cells, reveals crucial molecular mechanisms for identifying cellular sources and inducers of functional cell renewal. This provides an opportunity to identify specific cellular sources and mechanisms of regeneration, which could have clinical applications in treating various pathologies, including in vitro cell-based technologies, and deepen our understanding of regeneration in different physiological conditions.

A set of circulating microRNAs belonging to the 14q32 chromosome locus identifies two subgroups of individuals with recent-onset type 1 diabetes

Circulating microRNAs (miRNAs) are linked to the onset and progression of type 1 diabetes mellitus (T1DM), thus representing potential disease biomarkers. In this study, we employed a multiplatform sequencing approach to analyze circulating miRNAs in an extended cohort of prospectively evaluated recent-onset T1DM individuals from the INNODIA consortium. Our findings reveal that a set of miRNAs located within T1DM susceptibility chromosomal locus 14q32 distinguishes two subgroups of individuals. To validate our results, we conducted additional analyses on a second cohort of T1DM individuals, confirming the identification of these subgroups, which we have named cluster A and cluster B. Remarkably, cluster B T1DM individuals, who exhibit increased expression of a set of 14q32 miRNAs, show better glycemic control and display a different blood immunomics profile. Our findings suggest that this set of circulating miRNAs can identify two different T1DM subgroups with distinct blood immunomics at baseline and clinical outcomes during follow-up.

The immunology of type 1 diabetes

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

Gαz-independent and -dependent Improvements With EPA Supplementation on the Early Type 1 Diabetes Phenotype of NOD Mice

Prostaglandin E2 (PGE2) is a key mediator of inflammation and is derived from the omega-6 polyunsaturated fatty acid, arachidonic acid (AA). In the β-cell, the PGE2 receptor, Prostaglandin EP3 receptor (EP3), is coupled to the unique heterotrimeric G protein alpha subunit, Gɑz to reduce the production of cyclic adenosine monophosphate (cAMP), a key signaling molecule that activates β-cell function, proliferation, and survival pathways. Nonobese diabetic (NOD) mice are a strong model of type 1 diabetes (T1D), and NOD mice lacking Gɑz are protected from hyperglycemia. Therefore, limiting systemic PGE2 production could potentially improve both the inflammatory and β-cell dysfunction phenotype of T1D. Here, we sought to evaluate the effect of eicosapentaenoic acid (EPA) feeding, which limits PGE2 production, on the early T1D phenotype of NOD mice in the presence and absence of Gαz. Wild-type and Gαz knockout NOD mice were fed a control or EPA-enriched diet for 12 weeks, beginning at age 4 to 5 weeks. Oral glucose tolerance, splenic T-cell populations, islet cytokine/chemokine gene expression, islet insulitis, measurements of β-cell mass, and measurements of β-cell function were quantified. EPA diet feeding and Gɑz loss independently improved different aspects of the early NOD T1D phenotype and coordinated to alter the expression of certain cytokine/chemokine genes and enhance incretin-potentiated insulin secretion. Our results shed critical light on the Gαz-dependent and -independent effects of dietary EPA enrichment and provide a rationale for future research into novel pharmacological and dietary adjuvant therapies for T1D.

AnnoSpat annotates cell types and quantifies cellular arrangements from spatial proteomics

Cellular composition and anatomical organization influence normal and aberrant organ functions. Emerging spatial single-cell proteomic assays such as Image Mass Cytometry (IMC) and Co-Detection by Indexing (CODEX) have facilitated the study of cellular composition and organization by enabling high-throughput measurement of cells and their localization directly in intact tissues. However, annotation of cell types and quantification of their relative localization in tissues remain challenging. To address these unmet needs for atlas-scale datasets like Human Pancreas Analysis Program (HPAP), we develop AnnoSpat (Annotator and Spatial Pattern Finder) that uses neural network and point process algorithms to automatically identify cell types and quantify cell-cell proximity relationships. Our study of data from IMC and CODEX shows the higher performance of AnnoSpat in rapid and accurate annotation of cell types compared to alternative approaches. Moreover, the application of AnnoSpat to type 1 diabetic, non-diabetic autoantibody-positive, and non-diabetic organ donor cohorts recapitulates known islet pathobiology and shows differential dynamics of pancreatic polypeptide (PP) cell abundance and CD8+ T cells infiltration in islets during type 1 diabetes progression.

The Importance of Intra-Islet Communication in the Function and Plasticity of the Islets of Langerhans during Health and Diabetes

Islets of Langerhans are anatomically dispersed within the pancreas and exhibit regulatory coordination between islets in response to nutritional and inflammatory stimuli. However, within individual islets, there is also multi-faceted coordination of function between individual beta-cells, and between beta-cells and other endocrine and vascular cell types. This is mediated partly through circulatory feedback of the major secreted hormones, insulin and glucagon, but also by autocrine and paracrine actions within the islet by a range of other secreted products, including somatostatin, urocortin 3, serotonin, glucagon-like peptide-1, acetylcholine, and ghrelin. Their availability can be modulated within the islet by pericyte-mediated regulation of microvascular blood flow. Within the islet, both endocrine progenitor cells and the ability of endocrine cells to trans-differentiate between phenotypes can alter endocrine cell mass to adapt to changed metabolic circumstances, regulated by the within-islet trophic environment. Optimal islet function is precariously balanced due to the high metabolic rate required by beta-cells to synthesize and secrete insulin, and they are susceptible to oxidative and endoplasmic reticular stress in the face of high metabolic demand. Resulting changes in paracrine dynamics within the islets can contribute to the emergence of Types 1, 2 and gestational diabetes.

DNA Methylation-Based Assessment of Cell Composition in Human Pancreas and Islets

Assessment of pancreas cell type composition is crucial to the understanding of the genesis of diabetes. Current approaches use immunodetection of protein markers, for example, insulin as a marker of β-cells. A major limitation of these methods is that protein content varies in physiological and pathological conditions, complicating the extrapolation to actual cell number. Here, we demonstrate the use of cell type-specific DNA methylation markers for determining the fraction of specific cell types in human islet and pancreas specimens. We identified genomic loci that are uniquely demethylated in specific pancreatic cell types and applied targeted PCR to assess the methylation status of these loci in tissue samples, enabling inference of cell type composition. In islet preparations, normalization of insulin secretion to β-cell DNA revealed similar β-cell function in pre-type 1 diabetes (T1D), T1D, and type 2 diabetes (T2D), which was significantly lower than in donors without diabetes. In histological pancreas specimens from recent-onset T1D, this assay showed β-cell fraction within the normal range, suggesting a significant contribution of β-cell dysfunction. In T2D pancreata, we observed increased α-cell fraction and normal β-cell fraction. Methylation-based analysis provides an accurate molecular alternative to immune detection of cell types in the human pancreas, with utility in the interpretation of insulin secretion assays and the assessment of pancreas cell composition in health and disease.

ARTICLE HIGHLIGHTS

Induction of islet autoimmunity to defective ribosomal product of the insulin gene as neoantigen after anti-cancer immunotherapy leading to autoimmune diabetes

Introduction

The autoimmune response in type 1 diabetes (T1D), in which the beta cells expressing aberrant or modified proteins are killed, resembles an effective antitumor response. Defective ribosomal protein products in tumors are targets of the anti-tumor immune response that is unleashed by immune checkpoint inhibitor (ICI) treatment in cancer patients. We recently described a defective ribosomal product of the insulin gene (INS-DRiP) that is expressed in stressed beta cells and targeted by diabetogenic T cells. T1D patient-derived INS-DRiP specific T cells can kill beta cells and are present in the insulitic lesion. T cells reactive to INS-DRiP epitopes are part of the normal T cell repertoire and are believed to be kept in check by immune regulation without causing autoimmunity.

Method

T cell autoreactivity was tested using a combinatorial HLA multimer technology measuring a range of epitopes of islet autoantigens and neoantigen INS-DRiP. INS-DRiP expression in human pancreas and insulinoma sections was tested by immunohistochemistry.

Results

Here we report the induction of islet autoimmunity to INS-DRiP and diabetes after ICI treatment and successful tumor remission. Following ICI treatment, T cells of the cancer patient were primed against INS-DRiP among other diabetogenic antigens, while there was no sign of autoimmunity to this neoantigen before ICI treatment. Next, we demonstrated the expression of INS-DRiP as neoantigen in both pancreatic islets and insulinoma by staining with a monoclonal antibody to INS-DRiP.

Discussion

These results bridge cancer and T1D as two sides of the same coin and point to neoantigen expression in normal islets and insulinoma that may serve as target of both islet autoimmunity and tumor-related autoimmunity.

An antigen-specific immunotherapeutic, AKS-107, deletes insulin-specific B cells and prevents murine autoimmune diabetes

Introduction

The antigen-presenting cell function of insulin-reactive B cells promotes type 1 diabetes (T1D) in non-obese diabetic (NOD) mice by stimulating pathogenic T cells leading to destruction of insulin-producing β-cells of pancreatic islets.

Methods/Results

To target insulin-reactive B cells, AKS-107, a human IgG1 Fc molecule fused with human insulin A and B chains, was engineered to retain conformational insulin epitopes that bound mouse and human B cell receptors but prevented binding to the insulin metabolic receptor. AKS-107 Fc-mediated deletion of insulin-reactive B cells was demonstrated via ex vivo and in vivo experiments with insulin-reactive B cell receptor transgenic mouse strains, VH125Tg/NOD and Tg125(H+L)/NOD. As an additional immune tolerance feature, the Y16A mutation of the insulin B(9-23) dominant T cell epitope was engineered into AKS-107 to suppress activation of insulin-specific T cells. In mice and non-human primates, AKS-107 was well-tolerated, non-immunogenic, did not cause hypoglycemia even at high doses, and showed an expectedly protracted pharmacokinetic profile. AKS-107 reproducibly prevented spontaneous diabetes from developing in NOD and VH125Tg/NOD mice that persisted for months after cessation of treatment, demonstrating durable immune tolerance.

Discussion

These preclinical outcomes position AKS-107 for clinical development in T1D prevention settings.

Oral gavage delivery of Cornus officinalis extract delays type 1 diabetes onset and hyperglycemia in non-obese diabetic (NOD) mice

Type 1 diabetes (T1D) is an autoimmune disease initiated by genetic predisposition and environmental influences, which result in the specific destruction of insulin-producing pancreatic β-cells. Currently, there are over 1.6 million cases of T1D in the United States with a worldwide incidence rate that has been increasing since 1990. Here, we examined the effect of Cornus officinalis (CO), a well-known ethnopharmacological agent, on a T1D model of the non-obese diabetic (NOD) mouse. A measured dose of CO extract was delivered into 10-week-old NOD mice by oral gavage for 15 weeks. T1D incidence and hyperglycemia were significantly lower in the CO-treated group as compared to the water gavage (WT) and a no handling or treatment control group (NHT) following treatment. T1D onset per group was 30%, 60% and 86% for the CO, WT and NHT groups, respectively. Circulating C-peptide was higher, and pancreatic insulitis was decreased in non-T1D CO-treated mice. Our findings suggest that CO may have therapeutic potential as both a safe and effective interventional agent to slow early stage T1D progression.

Paired box 6 gene delivery preserves beta cells and improves islet transplantation efficacy

Loss of pancreatic beta cells is the central feature of all forms of diabetes. Current therapies fail to halt the declined beta cell mass. Thus, strategies to preserve beta cells are imperatively needed. In this study, we identified paired box 6 (PAX6) as a critical regulator of beta cell survival. Under diabetic conditions, the human beta cell line EndoC-βH1, db/db mouse and human islets displayed dampened insulin and incretin signalings and reduced beta cell survival, which were alleviated by PAX6 overexpression. Adeno-associated virus (AAV)-mediated PAX6 overexpression in beta cells of streptozotocin-induced diabetic mice and db/db mice led to a sustained maintenance of glucose homeostasis. AAV-PAX6 transduction in human islets reduced islet graft loss and improved glycemic control after transplantation into immunodeficient diabetic mice. Our study highlights a previously unappreciated role for PAX6 in beta cell survival and raises the possibility that ex vivo PAX6 gene transfer into islets prior to transplantation might enhance islet graft function and transplantation outcome.

Emerging therapeutic options in the management of diabetes: recent trends, challenges and future directions

Diabetes is a serious health issue that causes a progressive dysregulation of carbohydrate metabolism due to insufficient insulin hormone, leading to consistently high blood glucose levels. According to the epidemiological data, the prevalence of diabetes has been increasing globally, affecting millions of individuals. It is a long-term condition that increases the risk of various diseases caused by damage to small and large blood vessels. There are two main subtypes of diabetes: type 1 and type 2, with type 2 being the most prevalent. Genetic and molecular studies have identified several genetic variants and metabolic pathways that contribute to the development and progression of diabetes. Current treatments include gene therapy, stem cell therapy, statin therapy, and other drugs. Moreover, recent advancements in therapeutics have also focused on developing novel drugs targeting these pathways, including incretin mimetics, SGLT2 inhibitors, and GLP-1 receptor agonists, which have shown promising results in improving glycemic control and reducing the risk of complications. However, these treatments are often expensive, inaccessible to patients in underdeveloped countries, and can have severe side effects. Peptides, such as glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), are being explored as a potential therapy for diabetes. These peptides are postprandial glucose-dependent pancreatic beta-cell insulin secretagogues and have received much attention as a possible treatment option. Despite these advances, diabetes remains a major health challenge, and further research is needed to develop effective treatments and prevent its complications. This review covers various aspects of diabetes, including epidemiology, genetic and molecular basis, and recent advancements in therapeutics including herbal and synthetic peptides.

Footprint of pancreas infiltrating and circulating immune cells throughout type 1 diabetes development

Introduction

Type 1 diabetes (T1D) is defined by immune cell infiltration of the pancreas, in particular the islets of Langerhans, referred to as insulitis, which is especially prominent during the early disease stages in association with decreased beta cell mass. An in-depth understanding of the dynamics and phenotype of the immune cells infiltrating the pancreas and the accompanying changes in their profiles in peripheral blood during T1D development is critical to generate novel preventive and therapeutic approaches, as well as to find biomarkers for the disease process.

Methods

Using multi-parameter flow cytometry, we explored the dynamic changes of immune cells infiltrating the pancreas and the pancreatic draining lymph nodes (PLN), compared to those in peripheral blood in female and male non-obese diabetic (NOD) mice during T1D progression.

Results

The early stages of T1D development were characterized by an influx of innate dendritic cells and neutrophils in the pancreas. While dendritic cells seemed to move in and out (to the PLN), neutrophils accumulated during the pre-symptomatic phase and reached a maximum at 8 weeks of age, after which their numbers declined. During disease progression, CD4+ and CD8+ T cells appeared to continuously migrate from the PLN to the pancreas, which coincided with an increase in beta cell autoimmunity and insulitis severity, and a decline in insulin content. At 12 weeks of age, CD4+ and especially CD8+ T cells in the pancreas showed a dramatic shift from naïve to effector memory phenotype, in contrast to the PLN, where most of these cells remained naïve. A large proportion of pancreas infiltrating CD4+ T cells were naïve, indicating that antigenic stimulation was not necessary to traffic and invade the pancreas. Interestingly, a pre-effector-like T cell dominated the peripheral blood. These cells were intermediates between naïve and effector memory cells as identified by single cell RNA sequencing and might be a potential novel therapeutic target.

Conclusion

These time- and tissue-dependent changes in the dynamics and functional states of CD4+ and CD8+ T cells are essential steps in our understanding of the disease process in NOD mice and need to be considered for the interpretation and design of disease-modifying therapies.

An Integrated Map of Cell Type-Specific Gene Expression in Pancreatic Islets

Pancreatic islets consist of multiple cell types that produce hormones required for glucose homeostasis, and islet dysfunction is a major factor in type 1 and type 2 diabetes. Numerous studies have assessed transcription across individual cell types using single-cell assays; however, there is no canonical reference of gene expression in islet cell types that is also easily accessible for researchers to query and use in bioinformatics pipelines. Here we present an integrated map of islet cell type-specific gene expression from 192,203 cells from single-cell RNA sequencing of 65 donors without diabetes, donors who were type 1 diabetes autoantibody positive, donors with type 1 diabetes, and donors with type 2 diabetes from the Human Pancreas Analysis Program. We identified 10 distinct cell types, annotated subpopulations of several cell types, and defined cell type-specific marker genes. We tested differential expression within each cell type across disease states and identified 1,701 genes with significant changes in expression, with most changes observed in β-cells from donors with type 1 diabetes. To facilitate user interaction, we provide several single-cell visualization and reference mapping tools, as well as the open-access analytical pipelines used to create this reference. The results will serve as a valuable resource to investigators studying islet biology.

ARTICLE HIGHLIGHTS

The pathogenic "symphony" in type 1 diabetes: A disorder of the immune system, β cells, and exocrine pancreas

Type 1 diabetes (T1D) is widely considered to result from the autoimmune destruction of insulin-producing β cells. This concept has been a central tenet for decades of attempts seeking to decipher the disorder's pathogenesis and prevent/reverse the disease. Recently, this and many other disease-related notions have come under increasing question, particularly given knowledge gained from analyses of human T1D pancreas. Perhaps most crucial are findings suggesting that a collective of cellular constituents-immune, endocrine, and exocrine in origin-mechanistically coalesce to facilitate T1D. This review considers these emerging concepts, from basic science to clinical research, and identifies several key remaining knowledge voids.

Stem cell-like memory T cells: Role in viral infections and autoimmunity

Stem cell-like memory T (T_SCM) cells possess stem cell properties including multipotency and self-renewal and are being recognized as emerging players in various human diseases. Advanced technologies such as multiparametric flowcytometry and single cell sequencing have enabled their identification and molecular characterization. In case of chronic viral diseases such as human immunodeficiency virus-1, CD4+ T_SCM cells, serve as major reservoirs of the latent virus. However, during immune activation and functional exhaustion of effector T cells, these cells also possess the potential to replenish the pool of functional effector cells to curtail the infection. More recently, these cells are speculated to play important role in protective immunity following acute viral infections such as coronavirus disease 2019 and might be amenable for therapeutics by ex vivo expansion. Similarly, studies are also investigating their pathological role in driving autoimmune responses. However, there are several gaps in the understanding of the role of T_SCM cells in viral and autoimmune diseases to make them potential therapeutic targets. In this minireview, we have attempted an updated compilation of the dyadic role of these complex T_SCM cells during such human diseases along with their biology and transcriptional programs.

Construction of engineered 3D islet micro-tissue using porcine decellularized ECM for the treatment of diabetes

Islet transplantation improves diabetes patients' long-term blood glucose control, but its success and utility are limited by cadaver availability, quality, and considerable islet loss after transplantation due to ischemia and inadequate angiogenesis. This study used adipose, pancreatic, and liver tissue decellularized extracellular matrix (dECM) hydrogels in an effort to recapitulate the islet sites inside the pancreas in vitro, and successfully generated viable and functional heterocellular islet micro-tissues using islet cells, human umbilical vein endothelial cells, and adipose-derived mesenchymal stem cells. The three-dimensional (3D) islet micro-tissues maintained prolonged viability and normal secretory function, and showed high drug sensitivity in drug testing. Meanwhile, the 3D islet micro-tissues significantly enhanced survival and graft function in a mouse model of diabetes. These supportive 3D physiomimetic dECM hydrogels can be used not only for islet micro-tissue culture in vitro, but also have great promise for islet transplantation for the treatment of diabetes.

The human α cell in health and disease

In commemoration of 100 years since the discovery of glucagon, we review current knowledge about the human α cell. Alpha cells make up 30-40% of human islet endocrine cells and play a major role in regulating whole-body glucose homeostasis, largely through the direct actions of their main secretory product - glucagon - on peripheral organs. Additionally, glucagon and other secretory products of α cells, namely acetylcholine, glutamate, and glucagon-like peptide-1, have been shown to play an indirect role in the modulation of glucose homeostasis through autocrine and paracrine interactions within the islet. Studies of glucagon's role as a counterregulatory hormone have revealed additional important functions of the α cell, including the regulation of multiple aspects of energy metabolism outside that of glucose. At the molecular level, human α cells are defined by the expression of conserved islet-enriched transcription factors and various enriched signature genes, many of which have currently unknown cellular functions. Despite these common threads, notable heterogeneity exists amongst human α cell gene expression and function. Even greater differences are noted at the inter-species level, underscoring the importance of further study of α cell physiology in the human context. Finally, studies on α cell morphology and function in type 1 and type 2 diabetes, as well as other forms of metabolic stress, reveal a key contribution of α cell dysfunction to dysregulated glucose homeostasis in disease pathogenesis, making targeting the α cell an important focus for improving treatment.

Nanomaterials for antigen-specific immune tolerance therapy

Impairment of immune tolerance might cause autologous tissue damage or overactive immune response against non-pathogenic molecules. Although autoimmune disease and allergy have complicated pathologies, the current strategies have mainly focused on symptom amelioration or systemic immunosuppression which can lead to fatal adverse events. The induction of antigen-specific immune tolerance may provide therapeutic benefits to autoimmune disease and allergic response, while reducing nonspecific immune adverse responses. Diverse nanomaterials have been studied to induce antigen-specific immune tolerance therapy. This review will cover the immunological background of antigen-specific tolerance, clinical importance of antigen-specific immune tolerance, and nanomaterials designed for autoimmune and allergic diseases. As nanomaterials for modulating immune tolerances, lipid-based nanoparticles, polymeric nanoparticles, and biological carriers have been covered. Strategies to provide antigen-specific immune tolerance have been addressed. Finally, current challenges and perspectives of nanomaterials for antigen-specific immune tolerance therapy will be discussed.

A genomic data archive from the Network for Pancreatic Organ donors with Diabetes

The Network for Pancreatic Organ donors with Diabetes (nPOD) is the largest biorepository of human pancreata and associated immune organs from donors with type 1 diabetes (T1D), maturity-onset diabetes of the young (MODY), cystic fibrosis-related diabetes (CFRD), type 2 diabetes (T2D), gestational diabetes, islet autoantibody positivity (AAb+), and without diabetes. nPOD recovers, processes, analyzes, and distributes high-quality biospecimens, collected using optimized standard operating procedures, and associated de-identified data/metadata to researchers around the world. Herein describes the release of high-parameter genotyping data from this collection. 372 donors were genotyped using a custom precision medicine single nucleotide polymorphism (SNP) microarray. Data were technically validated using published algorithms to evaluate donor relatedness, ancestry, imputed HLA, and T1D genetic risk score. Additionally, 207 donors were assessed for rare known and novel coding region variants via whole exome sequencing (WES). These data are publicly-available to enable genotype-specific sample requests and the study of novel genotype:phenotype associations, aiding in the mission of nPOD to enhance understanding of diabetes pathogenesis to promote the development of novel therapies.

Gene expression signature predicts rate of type 1 diabetes progression

BACKGROUND

Type 1 diabetes is a complex heterogenous autoimmune disease without therapeutic interventions available to prevent or reverse the disease. This study aimed to identify transcriptional changes associated with the disease progression in patients with recent-onset type 1 diabetes.

METHODS

Whole-blood samples were collected as part of the INNODIA study at baseline and 12 months after diagnosis of type 1 diabetes. We used linear mixed-effects modelling on RNA-seq data to identify genes associated with age, sex, or disease progression. Cell-type proportions were estimated from the RNA-seq data using computational deconvolution. Associations to clinical variables were estimated using Pearson's or point-biserial correlation for continuous and dichotomous variables, respectively, using only complete pairs of observations.

FINDINGS

We found that genes and pathways related to innate immunity were downregulated during the first year after diagnosis. Significant associations of the gene expression changes were found with ZnT8A autoantibody positivity. Rate of change in the expression of 16 genes between baseline and 12 months was found to predict the decline in C-peptide at 24 months. Interestingly and consistent with earlier reports, increased B cell levels and decreased neutrophil levels were associated with the rapid progression.

INTERPRETATION

There is considerable individual variation in the rate of progression from appearance of type 1 diabetes-specific autoantibodies to clinical disease. Patient stratification and prediction of disease progression can help in developing more personalised therapeutic strategies for different disease endotypes.

FUNDING

A full list of funding bodies can be found under Acknowledgments.

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.

Integrated Physiology of the Exocrine and Endocrine Compartments in Pancreatic Diseases: Workshop Proceedings

The Integrated Physiology of the Exocrine and Endocrine Compartments in Pancreatic Diseases workshop was a 1.5-day scientific conference at the National Institutes of Health (Bethesda, MD) that engaged clinical and basic science investigators interested in diseases of the pancreas. This report provides a summary of the proceedings from the workshop. The goals of the workshop were to forge connections and identify gaps in knowledge that could guide future research directions. Presentations were segregated into six major theme areas, including 1) pancreas anatomy and physiology, 2) diabetes in the setting of exocrine disease, 3) metabolic influences on the exocrine pancreas, 4) genetic drivers of pancreatic diseases, 5) tools for integrated pancreatic analysis, and 6) implications of exocrine-endocrine cross talk. For each theme, multiple presentations were followed by panel discussions on specific topics relevant to each area of research; these are summarized here. Significantly, the discussions resulted in the identification of research gaps and opportunities for the field to address. In general, it was concluded that as a pancreas research community, we must more thoughtfully integrate our current knowledge of normal physiology as well as the disease mechanisms that underlie endocrine and exocrine disorders so that there is a better understanding of the interplay between these compartments.

The extent and magnitude of islet T cell infiltration as powerful tools to define the progression to type 1 diabetes

AIMS/HYPOTHESIS

Insulitis is not present in all islets, and it is elusive in humans. Although earlier studies focused on islets that fulfilled certain criteria (e.g. ≥15 CD45⁺ cells or ≥6 CD3⁺ cells), there is a fundamental lack of understanding of the infiltration dynamics in terms of its magnitude (i.e. how much) and extent (i.e. where). Here, we aimed to perform an in-depth characterisation of T cell infiltration by investigating islets with moderate (1-5 CD3⁺ cells) and high (≥6 CD3⁺ cells) infiltration in individuals with and without type 1 diabetes.

METHODS

Pancreatic tissue sections from 15 non-diabetic, eight double autoantibody-positive and ten type 1 diabetic (0-2 years of disease duration) organ donors were obtained from the Network for Pancreatic Organ Donors with Diabetes, and stained for insulin, glucagon, CD3 and CD8 by immunofluorescence. T cell infiltration was quantified in a total of 8661 islets using the software QuPath. The percentage of infiltrated islets and islet T cell density were calculated. To help standardise the analysis of T cell infiltration, we used cell density data to develop a new T cell density threshold capable of differentiating non-diabetic and type 1 diabetic donors.

RESULTS

Our analysis revealed that 17.1% of islets in non-diabetic donors, 33% of islets in autoantibody-positive and 32.5% of islets in type 1 diabetic donors were infiltrated by 1 to 5 CD3⁺ cells. Islets infiltrated by ≥6 CD3⁺ cells were rare in non-diabetic donors (0.4%) but could be found in autoantibody-positive (4.5%) and type 1 diabetic donors (8.2%). CD8⁺ and CD8^- populations followed similar patterns. Likewise, T cell density was significantly higher in the islets of autoantibody-positive donors (55.4 CD3⁺ cells/mm²) and type 1 diabetic donors (74.8 CD3⁺ cells/mm²) compared with non-diabetic individuals (17.3 CD3⁺ cells/mm²), which was accompanied by higher exocrine T cell density in type 1 diabetic individuals. Furthermore, we showed that the analysis of a minimum of 30 islets and the use of a reference mean value for T cell density of 30 CD3⁺ cells/mm² (the 30-30 rule) can differentiate between non-diabetic and type 1 diabetic donors with high specificity and sensitivity. In addition, it can classify autoantibody-positive individuals as non-diabetic or type 1 diabetic-like.

CONCLUSIONS/INTERPRETATION

Our data indicates that the proportion of infiltrated islets and T cell density change dramatically during the course of type 1 diabetes, and these changes can be already observed in double autoantibody-positive individuals. This suggests that, as disease progresses, T cell infiltration extends throughout the pancreas, reaching the islets and exocrine compartment. While it predominantly targets insulin-containing islets, large accumulations of cells are rare. Our study fulfils the need to further understand T cell infiltration, not only after diagnosis but also in individuals with diabetes-related autoantibodies. Furthermore, the development and application of new analytical tools based on T cell infiltration, like the 30-30 rule, will allow us to correlate islet infiltration with demographic and clinical variables with the aim of identifying individuals at the very early stages of the disease.

New-onset type 1 diabetes and severe acute respiratory syndrome coronavirus 2 infection

Type 1 diabetes (T1D) is a condition characterized by an absolute deficiency of insulin. Loss of insulin-producing pancreatic islet β cells is one of the many causes of T1D. Viral infections have long been associated with new-onset T1D and the balance between virulence and host immunity determines whether the viral infection would lead to T1D. Herein, we detail the dynamic interaction of pancreatic β cells with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the host immune system with respect to new-onset T1D. Importantly, β cells express the crucial entry receptors and multiple studies confirmed that β cells are infected by SARS-CoV-2. Innate immune system effectors, such as natural killer cells, can eliminate such infected β cells. Although CD4⁺ CD25⁺ FoxP3⁺ regulatory T (T_REG ) cells provide immune tolerance to prevent the destruction of the islet β-cell population by autoantigen-specific CD8⁺ T cells, it can be speculated that SARS-CoV-2 infection may compromise self-tolerance by depleting T_REG -cell numbers or diminishing T_REG -cell functions by repressing Forkhead box P3 (FoxP3) expression. However, the expansion of β cells by self-duplication, and regeneration from progenitor cells, could effectively replace lost β cells. Appearance of islet autoantibodies following SARS-CoV-2 infection was reported in a few cases, which could imply a breakdown of immune tolerance in the pancreatic islets. However, many of the cases with newly diagnosed autoimmune response following SARS-CoV-2 infection also presented with significantly high HbA_1c (glycated hemoglobin) levels that indicated progression of an already set diabetes, rather than new-onset T1D. Here we review the potential underlying mechanisms behind loss of functional β-cell mass as a result of SARS-CoV-2 infection that can trigger new-onset T1D.

Prebiotic inulin nanocoating for pancreatic islet surface engineering

Pancreatic islet surface engineering has been proposed as an "easy-to-adopt" approach to enhance post-transplantation islet engraftment for treatment against diabetes. Inulin is an FDA-approved dietary prebiotic with reported anti-diabetic, anti-inflammatory, anti-hypoxic and pro-angiogenic properties. We therefore assessed whether inulin would be a viable option for islet surface engineering. Inulin was oxidized to generate inulin-CHO, which would bind to the cell membrane via covalent bond formation between -CHO and -NH₂ across the islet cell membrane. In vitro assessments demonstrated enhanced islet viability and better glucose-induced insulin secretion from inulin-coated (5 mg mL^-1) islets, which was accompanied by enhanced revascularization, shown as significantly enhanced tube formation and branching of islet endothelial MS1 cells following co-culture with inulin-coated islets. Reduction of cytokine-induced cell death was also observed from inulin-coated islets following exposure to pro-inflammatory cytokine LPS. LPS-induced ROS production was significantly dampened by 44% in inulin-coated islets when compared to controls. RNA-seq analysis of inulin-coated and control islets identified expression alterations of genes involved in islet function, vascular formation and immune regulation, supporting the positive impact of inulin on islet preservation. In vivo examination using streptozotocin (STZ)-induced hyperglycemic mice further showed moderately better maintained plasma glucose levels in mice received transplantation of inulin-coated islets, attributable to ameliorated CD45⁺ immune cell infiltration and improved in vivo graft vascularization. We therefore propose islet surface engineering with inulin as safe and beneficial, and further assessment is required to verify its applicability in clinical islet transplantation.

Cell-Surface Autoantibody Targets Zinc Transporter-8 (ZnT8) for In Vivo β-Cell Imaging and Islet-Specific Therapies

Type 1 diabetes (T1D) is a disease in which autoimmune attacks are directed at the insulin-producing β-cell in the pancreatic islet. Autoantigens on the β-cell surface membrane are specific markers for molecular recognition and targets for engagement by autoreactive B lymphocytes, which produce islet cell surface autoantibody (ICSA) upon activation. We report the cloning of an ICSA (mAb43) that recognizes a major T1D autoantigen, ZnT8, with a subnanomolar binding affinity and conformation specificity. We demonstrate that cell-surface binding of mAb43 protects the extracellular epitope of ZnT8 against immunolabeling by serum ICSA from a patient with T1D. Furthermore, mAb43 exhibits in vitro and ex vivo specificity for islet cells, mirroring the exquisite specificity of islet autoimmunity in T1D. Systemic administration of mAb43 yields a pancreas-specific biodistribution in mice and islet homing of an mAb43-linked imaging payload through the pancreatic vasculature, thereby validating the in vivo specificity of mAb43. Identifying ZnT8 as a major antigenic target of ICSA allows for research into the molecular recognition and engagement of autoreactive B cells in the chronic phase of T1D progression. The in vivo islet specificity of mAb43 could be further exploited to develop in vivo imaging and islet-specific immunotherapies.

Identification of key regulatory genes and their working mechanisms in type 1 diabetes

BACKGROUND

Type 1 diabetes (T1D) is an autoimmune disease characterized by the destruction of beta cells in pancreatic islets. Identification of the key genes involved in T1D progression and their mechanisms of action may contribute to a better understanding of T1D.

METHODS

The microarray profile of T1D-related gene expression was searched using the Gene Expression Omnibus (GEO) database. Then, the expression data of two messenger RNAs (mRNAs) were integrated for Weighted Gene Co-Expression Network Analysis (WGCNA) to generate candidate genes related to T1D. In parallel, T1D microRNA (miRNA) data were analyzed to screen for possible regulatory miRNAs and their target genes. An miRNA-mRNA regulatory network was then established to predict the key regulatory genes and their mechanisms.

RESULTS

A total of 24 modules (i.e., clusters/communities) were selected using WGCNA analysis, in which three modules were significantly associated with T1D. Further correlation analysis of the gene module revealed 926 differentially expressed genes (DEGs), of which 327 genes were correlated with T1D. Analysis of the miRNA microarray showed that 13 miRNAs had significant expression differences in T1D. An miRNA-mRNA network was established based on the prediction of miRNA target genes and the combined analysis of mRNA, in which the target genes of two miRNAs were found in T1D correlated genes.

CONCLUSION

An miRNA-mRNA network for T1D was established, based on which 2 miRNAs and 12 mRNAs were screened, suggesting that they may play key regulatory roles in the initiation and development of T1D.

A discovery-based proteomics approach identifies protein disulphide isomerase (PDIA1) as a biomarker of β cell stress in type 1 diabetes

BACKGROUND

Stress responses within the β cell have been linked with both increased β cell death and accelerated immune activation in type 1 diabetes (T1D). At present, information on the timing and scope of these responses as well as disease-related changes in islet β cell protein expression during T1D development is lacking.

METHODS

Data independent acquisition-mass spectrometry was performed on islets collected longitudinally from NOD mice and NOD-SCID mice rendered diabetic through T cell adoptive transfer.

FINDINGS

In islets collected from female NOD mice at 10, 12, and 14 weeks of age, we found a time-restricted upregulation of proteins involved in stress mitigation and maintenance of β cell function, followed by loss of expression of protective proteins that heralded diabetes onset. EIF2 signalling and the unfolded protein response, mTOR signalling, mitochondrial function, and oxidative phosphorylation were commonly modulated pathways in both NOD mice and NOD-SCID mice rendered acutely diabetic by T cell adoptive transfer. Protein disulphide isomerase A1 (PDIA1) was upregulated in NOD islets and pancreatic sections from human organ donors with autoantibody positivity or T1D. Moreover, PDIA1 plasma levels were increased in pre-diabetic NOD mice and in the serum of children with recent-onset T1D compared to non-diabetic controls.

INTERPRETATION

We identified a core set of modulated pathways across distinct mouse models of T1D and identified PDIA1 as a potential human biomarker of β cell stress in T1D.

FUNDING

NIH (R01DK093954, DK127308, U01DK127786, UC4DK104166, R01DK060581, R01GM118470, and 5T32DK101001-09). VA Merit Award I01BX001733. JDRF (2-SRA-2019-834-S-B, 2-SRA-2018-493-A-B, 3-PDF-20016-199-A-N, 5-CDA-2022-1176-A-N, and 3-PDF-2017-385-A-N).

Umbilical cord mesenchymal stromal cells transplantation delays the onset of hyperglycemia in the RIP-B7.1 mouse model of experimental autoimmune diabetes through multiple immunosuppressive and anti-inflammatory responses

Type 1 diabetes mellitus (T1DM) is an autoimmune disorder specifically targeting pancreatic islet beta cells. Despite many efforts focused on identifying new therapies able to counteract this autoimmune attack and/or stimulate beta cells regeneration, TD1M remains without effective clinical treatments providing no clear advantages over the conventional treatment with insulin. We previously postulated that both the inflammatory and immune responses and beta cell survival/regeneration must be simultaneously targeted to blunt the progression of disease. Umbilical cord-derived mesenchymal stromal cells (UC-MSC) exhibit anti-inflammatory, trophic, immunomodulatory and regenerative properties and have shown some beneficial yet controversial effects in clinical trials for T1DM. In order to clarify conflicting results, we herein dissected the cellular and molecular events derived from UC-MSC intraperitoneal administration (i.p.) in the RIP-B7.1 mouse model of experimental autoimmune diabetes. Intraperitoneal (i.p.) transplantation of heterologous mouse UC-MSC delayed the onset of diabetes in RIP-B7.1 mice. Importantly, UC-MSC i. p. transplantation led to a strong peritoneal recruitment of myeloid-derived suppressor cells (MDSC) followed by multiple T-, B- and myeloid cells immunosuppressive responses in peritoneal fluid cells, spleen, pancreatic lymph nodes and the pancreas, which displayed significantly reduced insulitis and pancreatic infiltration of T and B Cells and pro-inflammatory macrophages. Altogether, these results suggest that UC-MSC i. p. transplantation can block or delay the development of hyperglycemia through suppression of inflammation and the immune attack.

Insulitis in Human Type 1 Diabetic Pancreas: From Stem Cell Grafting to Islet Organoids for a Successful Cell-Based Therapy

Type 1 diabetes (T1D) is an autoimmune disease with immune cells' islet infiltration (called "insulitis"), which leads to beta cell loss. Despite being the critical element of T1D occurrence and pathogenesis, insulitis is often present in a limited percentage of islets, also at diagnosis. Therefore, it is needed to define reproducible methods to detect insulitis and beta-cell decline, to allow accurate and early diagnosis and to monitor therapy. However, this goal is still far due to the morphological aspect of islet microvasculature, which is rather dense and rich, and is considerably rearranged during insulitis. More studies on microvasculature are required to understand if contrast-enhanced ultrasound sonography measurements of pancreatic blood-flow dynamics may provide a clinically deployable predictive marker to predict disease progression and therapeutic reversal in pre-symptomatic T1D patients. Therefore, it is needed to clarify the relation between insulitis and the dynamics of β cell loss and with coexisting mechanisms of dysfunction, according to clinical stage, as well as the micro vessels' dynamics and microvasculature reorganization. Moreover, the ideal cell-based therapy of T1D should start from an early diagnosis allowing a sufficient isolation of specific Procr+ progenitors, followed by the generation and expansion of islet organoids, which could be transplanted coupled to an immune-regulatory therapy which will permit the maintenance of pancreatic islets and an effective and long-lasting insulitis reversal.

Inside the β Cell: Molecular Stress Response Pathways in Diabetes Pathogenesis

The pathogeneses of the 2 major forms of diabetes, type 1 and type 2, differ with respect to their major molecular insults (loss of immune tolerance and onset of tissue insulin resistance, respectively). However, evidence suggests that dysfunction and/or death of insulin-producing β-cells is common to virtually all forms of diabetes. Although the mechanisms underlying β-cell dysfunction remain incompletely characterized, recent years have witnessed major advances in our understanding of the molecular pathways that contribute to the demise of the β-cell. Cellular and environmental factors contribute to β-cell dysfunction/loss through the activation of molecular pathways that exacerbate endoplasmic reticulum stress, the integrated stress response, oxidative stress, and impaired autophagy. Whereas many of these stress responsive pathways are interconnected, their individual contributions to glucose homeostasis and β-cell health have been elucidated through the development and interrogation of animal models. In these studies, genetic models and pharmacological compounds have enabled the identification of genes and proteins specifically involved in β-cell dysfunction during diabetes pathogenesis. Here, we review the critical stress response pathways that are activated in β cells in the context of the animal models.

Therapeutic Strategies Targeting Pancreatic Islet β-Cell Proliferation, Regeneration, and Replacement

Diabetes results from insufficient insulin production by pancreatic islet β-cells or a loss of β-cells themselves. Restoration of regulated insulin production is a predominant goal of translational diabetes research. Here, we provide a brief overview of recent advances in the fields of β-cell proliferation, regeneration, and replacement. The discovery of therapeutic targets and associated small molecules has been enabled by improved understanding of β-cell development and cell cycle regulation, as well as advanced high-throughput screening methodologies. Important findings in β-cell transdifferentiation, neogenesis, and stem cell differentiation have nucleated multiple promising therapeutic strategies. In particular, clinical trials are underway using in vitro-generated β-like cells from human pluripotent stem cells. Significant challenges remain for each of these strategies, but continued support for efforts in these research areas will be critical for the generation of distinct diabetes therapies.

Restoring tolerance to β-cells in Type 1 diabetes: Current and emerging strategies

Type 1 diabetes (T1D) results from insulin insufficiency due to islet death and dysfunction following T cell-mediated autoimmune attack. The technical feasibility of durable, functional autologous islet restoration is progressing such that it presents the most likely long-term cure for T1D but cannot succeed without the necessary counterpart of clinically effective therapeutic strategies that prevent grafted islets' destruction by pre-existing anti-islet T cells. While advances have been made in broad immunosuppression to lower off-target effects, the risk of opportunistic infections and cancers remains a concern, especially for well-managed T1D patients. Current immunomodulatory strategies in development focus on autologous Treg expansion, treatments to decrease antigen presentation and T effector (Teff) activation, and broad depletion of T cells with or without hematopoietic stem cell transplants. Emerging strategies harnessing the intensified DNA damage response present in expanding T cells, exacerbating their already high sensitivity to apoptosis to abate autoreactive Teff cells.

The frequency of CD4+ and CD8+ circulating T stem cell memory in type 1 diabetes

Introduction

Methods

Results

Conclusion

Abnormal Expression of an Insulin Synthesizing Enzyme in Islets of Adult Autoantibody Positive Donors

The observation that the two active forms of proprotein convertase 1/3 (PC1/3) were differentially expressed in beta cells of normal islets raised the possibility that this heterogeneity is lost during type 1 diabetes (T1D) progression. To test this hypothesis, the expression of the convertase was evaluated by confocal microscopy in sections of human pancreas of autoantibody positive (AA+) and T1D donors and compared with that of control. Islets of T1D pancreas were comprised of beta cells expressing either low or high PC1/3 levels and all islets of a pancreatic section contained only one beta cell type. Pancreata of AA+ donors contained either of these two classes of islets intermixed with normal islets comprised of beta cells with heterogeneous PC1/3 expression. This alteration affected the expression of proinsulin and insulin, which in most AA+ and T1D donors were lower than in controls. The present results indicate that the heterogeneity of PC1/3 expression is lost in all beta cells in a subset islets of AA+ donors and in all islets of T1D donors. These findings suggest that the heterogeneity of PC1/3 expression is a biomarker of human beta cell health and that its loss coincides with the initial stages of T1D.

Adult-onset autoimmune diabetes

Adult-onset autoimmune (AOA) diabetes pathophysiology starts with immune changes, followed by dysglycaemia and overt disease. AOA diabetes can occur as classic type 1 diabetes when associated with severe loss of insulin secretion. More frequently, it is diagnosed as latent autoimmune diabetes in adults, a slowly progressing form with late onset, a long period not requiring insulin, and it is often misdiagnosed as type 2 diabetes. As its clinical presentation varies remarkably and immune markers often lack specificity, it is challenging to classify each case ad hoc, especially when insulin treatment is not required at diagnosis. Proper care of AOA diabetes aims to prevent complications and to improve quality of life and life expectancy. To achieve these goals, attention should be paid to lifestyle factors, with the aid of pharmacological therapies properly tailored to each individual clinical setting. Given the heterogeneity of the disease, choosing the right therapy for AOA diabetes is challenging. Most of the trials testing disease-modifying therapies for autoimmune diabetes are conducted in people with childhood onset, whereas non-insulin diabetes therapies have mostly been studied in the larger population with type 2 diabetes. More randomized controlled trials of therapeutic agents in AOA diabetes are needed.

Exocrine and Endocrine Inflammation Increases Cellular Replication in the Pancreatic Duct Compartment in Type 1 Diabetes

Context

We recently demonstrated increased cellular proliferation in the pancreatic ductal gland (PDG) compartment of organ donors with type 1 diabetes, suggesting that PDGs may harbor progenitor cells capable of pancreatic regeneration.

Objective

We evaluated the impact of diabetes and pancreatic inflammation on PDG and interlobular duct (ILD) cellular proliferation and profiles.

Methods

Endocrine hormone expression (insulin, glucagon, somatostatin, pancreatic polypeptide) and proliferating Ki67+ cells were localized within the PDG and ILD compartments by multicolor immunohistochemistry in cross-sections from the head, body, and tail regions of pancreata from those with (n = 31) or without type 1 diabetes (n = 43). Whole-slide scanned images were analyzed using digital pathology.

Results

Type 1 diabetes donors with insulitis or histologically identified pancreatitis had increased cellular replication in the ILD and PDG compartments. Interestingly, while cellular proliferation within the pancreatic ductal tree was significantly increased in type 1 diabetes (PDG mean = 3.36%, SEM = 1.06; ILD mean = 2.78%, SEM = 0.97) vs nondiabetes(ND) subjects without pancreatic inflammation (PDG mean = 1.18%, SEM = 0.42; ILD mean = 0.74%, SEM = 0.15, P < 0.05), robust replication was also observed in ND donors with pancreatitis (PDG mean = 3.52%, SEM = 1.33; ILD mean = 2.18%, SEM = 0.54, P < 0.05). Few polyhormonal cells were present in the ILD (type 1 diabetes = 0.04 ± 0.02%; ND = 0.08 ± 0.03%, P = 0.40) or PDG compartment (type 1 diabetes = 0.02 ± 0.01%; ND = 0.08 ± 0.13%, P = 0.63).

Conclusion

These data suggest that increased pancreatic ductal cell replication is associated with sustained pancreatic inflammation; however, as replicating cells were hormone-negative, PDGs do not appear to represent a compelling endogenous source of hormone-positive endocrine cells.

Antigen-specific immunotherapies in type 1 diabetes

Type 1 diabetes mellitus (T1DM) is an autoimmune disease caused by the destruction of pancreatic beta cells, in which immune system disorder plays an important role. Finding a cure for T1DM and restoring beta cell function has been a long-standing goal. Research has shown that immune regulation with pancreatic islet auto-antigens may be the most specific and safe treatment for T1DM. Immunological intervention using diabetogenic auto-antigens as a target can help identify T1DM in high-risk individuals by early screening of autoantibodies (AAbs) before the loss of pancreatic islet function and thus achieve primary prevention of T1DM. However, induction of self-tolerance in patients with pre-diabetes can also slow down the attack of autoimmunity, and achieve secondary prevention. Antigen-based immune therapy opens up new avenues for the prevention and treatment of T1DM. The zinc transporter 8 (ZnT8) protein, presents in the serum of pre-diabetic and diabetic patients, is immunogenic and can cause T1D autoimmune responses. ZnT8 has become a potential target of humoral autoimmunity; it is of great significance for the early diagnosis of T1D. ZnT8-specific CD8⁺ T cells can be detected in most T1DM patients, and play a key role in the progression of T1D. As an immunotherapy target, it can improve the dysfunction of beta cells in T1DM and provide new ideas for the treatment of T1D. In this review, we summarize research surrounding antigen-specific immunotherapies (ASI) over the past 10 years and the ZnT8 antigen as an autoimmune target to induce self-tolerance for T1DM.

Immunological balance between Treg and Th17 lymphocytes as a key element of type 1 diabetes progression in children

Type 1 diabetes (T1D) is autoimmune destruction of the beta cells of pancreatic islets. Due to complexity of that disease, the mechanisms leading to the tolerance breakdown are still not fully understood. Previous hypothesis of imbalance in the Th1 and Th2 cells as the main contributing factor has been recently changed towards role of other lymphocytes – regulatory (Treg) and IL-17A-producing (Th17). Our study aims to assess changes within Treg and Th17 cells in newly diagnosed T1D pediatric patients and their association with disease remission. Flow cytometry implementation allowed for Treg and Th17 analysis in studied groups and further combination with clinical and laboratory data. In addition, expression of diabetes-related genes was tested and evaluated in context of their association with studied lymphocytes. Initial results revealed that Treg and ratio Treg/Th17 are significantly higher in T1D than in healthy controls. Moreover, patients with lower HbA1c and daily insulin requirements demonstrated higher levels of Tregs. Similar tendency for insulin intake was also observed in reference to Th17 cells, together with high levels of these cells in patients demonstrating higher values for c-peptide after 2 years. In low-level Treg patients, that subset correlates with the c-peptide in the admission stage. In addition, higher levels of IL-10 were associated with its correlation with HbA1c and insulin dosage. In the context of gene expression, moderate associations were demonstrated in T1D subjects inter alia between CTLA4 and Treg or ratio Treg/Th17. Cumulatively, our data indicate a possible novel role of Treg and Th17 in mechanism of type 1 diabetes. Moreover, potential prognostic value of these populations has been shown in reference to diabetes remission.

Temporal development of T cell receptor repertoires during childhood in health and disease

T cell receptor (TCR) sequences are exceptionally diverse and can now be comprehensively measured with next-generation sequencing technologies. However, a thorough investigation of longitudinal TCR repertoires throughout childhood in health and during development of a common childhood disease, type 1 diabetes (T1D), has not been undertaken. Here, we deep sequenced the TCR-β chain repertoires from longitudinal peripheral blood DNA samples at 4 time points beginning early in life (median age of 1.4 years) from children who progressed to T1D (n = 29) and age/sex-matched islet autoantibody-negative controls (n = 25). From 53 million TCR-β sequences, we show that the repertoire is extraordinarily diverse early in life and narrows with age independently of disease. We demonstrate the ability to identify specific TCR sequences, including those known to recognize influenza A and, separately, those specific for insulin and its precursor, preproinsulin. Insulin-reactive TCR-β sequences were more common and frequent in number as the disease progressed in those who developed T1D compared with genetically at risk nondiabetic children, and this was not the case for influenza-reactive sequences. As an independent validation, we sequenced and analyzed TCR-β repertoires from a cohort of new-onset T1D patients (n = 143), identifying the same preproinsulin-reactive TCRs. These results demonstrate an enrichment of preproinsulin-reactive TCR sequences during the progression to T1D, highlighting the importance of using disease-relevant TCR sequences as powerful biomarkers in autoimmune disorders.

ICAM-1 Abundance Is Increased in Pancreatic Islets of Hyperglycemic Female NOD Mice and Is Rapidly Upregulated by NF-κB in Pancreatic β-Cells

Type 1 diabetes (T1D) is classified as an autoimmune disease where pancreatic β-cells are specifically targeted by cells of the immune system. The molecular mechanisms underlying this process are not completely understood. Herein, we identified that the Icam1 gene and ICAM-1 protein were selectively elevated in female NOD mice relative to male mice, fitting with the sexual dimorphism of diabetes onset in this key mouse model of T1D. In addition, ICAM-1 abundance was greater in hyperglycemic female NOD mice than in age-matched normoglycemic female NOD mice. Moreover, we discovered that the Icam1 gene was rapidly upregulated in response to IL-1β in mouse, rat, and human islets and in 832/13 rat insulinoma cells. This early temporal genetic regulation requires key components of the NF-κB pathway and was associated with rapid recruitment of the p65 transcriptional subunit of NF-κB to corresponding κB elements within the Icam1 gene promoter. In addition, RNA polymerase II recruitment to the Icam1 gene promoter in response to IL-1β was consistent with p65 occupancy at κB elements, histone chemical modifications, and increased mRNA abundance. Thus, we conclude that β-cells undergo rapid genetic reprogramming by IL-1β to enhance expression of the Icam1 gene and that elevations in ICAM-1 are associated with hyperglycemia in NOD mice. These findings are highly relevant to, and highlight the importance of, pancreatic β-cell communication with the immune system. Collectively, these observations reveal a portion of the complex molecular events associated with onset and progression of T1D.

Urinary tract infection in patients with diabetes mellitus and the role of parental genetics in the emergence of the disease

This study aimed to assess the role of paternal genetics in the development of diabetic mellitus (DM) and determine the impact of DM on the urinary system by investigating the percentage of patients with urinary tract infection (UTI). The study included 100 people with DM; their ages ranged from 5 to 83 years. The DM and blood sugar levels were diagnosed clinically and at a laboratory in Al-Zahra Teaching Hospital and the outpatient clinics. The age, gender, and causes of DM and the family history of diabetes were reported. Isolation and identification of bacterial species were made depending on culture media and biochemical tests. The average age of patients was 47.7±5.5, and most of them were female (67%). The incidence of DM increased with age, and the main cause of DM was likely to be a genetic predisposition (family history), where 32% of patients appeared to have a positive family history and the presence of DM in both parents or only the mother had a significant role in increasing the genetic predisposition of developing DM. Among the non-genetic causes of DM, the most common was exposure to sudden psychological or nervous shock (41%). Obesity also had an important role in the development of diabetes, and also pregnancy and smoking. Moreover, 66% of patients with type 2 DM and all with type 1 DM suffered from UTIs. The main causative agents were E. coli (60%) and Proteus spp. (13%). The majority of patients suffering from UTIs (73%) were females. In conclusion, type 2 DM is the most common, especially in females, and increases with age. The main cause of DM was family genetic predisposition and sudden shocks. The current study also showed that most diabetic patients suffered from UTIs, especially females, and the main causes of UTI inflammation are E. coli isolates.

A decisive bridge between innate immunity and the pathognomonic morphological characteristics of type 1 diabetes demonstrated by instillation of heat-inactivated bacteria in the pancreatic duct of rats

AIMS

Periductal inflammation and accumulation of granulocytes and monocytes in the periislet area and in the exocrine pancreas is observed within hours after instillation of heat-inactivated bacteria in the ductal compartment of the pancreas in healthy rats. The present investigation was undertaken to study how the acute inflammation developed over time.

METHODS

Immunohistochemical evaluation of the immune response triggered by instillation of heat-inactivated bacteria in the ductal compartment in rats.

RESULTS

After three weeks, the triggered inflammation had vanished and pancreases showed normal morphology. However, a distinct accumulation of both CD4+ and CD8+ T cells within and adjacent to affected islets was found in one-third of the rats instilled with heat-inactivated E. faecalis, mimicking the insulitis seen at onset of human T1D. As in T1D, this insulitis affected a minority of islets and only certain lobes of the pancreases. Notably, a fraction of the T cells expressed the CD103 antigen, mirroring the recently reported presence of tissue resident memory T cells in the insulitis in humans with recent onset T1D.

CONCLUSIONS

The results presented unravel a previously unknown interplay between innate and acquired immunity in the formation of immunopathological events indistinguishable from those described in humans with recent onset T1D.

The β-Cell in Type 1 Diabetes Pathogenesis: A Victim of Circumstances or an Instigator of Tragic Events?

Recent reports have revived interest in the active role that β-cells may play in type 1 diabetes pathogenesis at different stages of disease. In some studies, investigators suggested an initiating role and proposed that type 1 diabetes may be primarily a disease of β-cells and only secondarily a disease of autoimmunity. This scenario is possible and invites the search for environmental triggers damaging β-cells. Another major contribution of β-cells may be to amplify autoimmune vulnerability and to eventually drive it into an intrinsic, self-detrimental state that turns the T cell-mediated homicide into a β-cell suicide. On the other hand, protective mechanisms are also mounted by β-cells and may provide novel therapeutic targets to combine immunomodulatory and β-cell protective agents. This integrated view of autoimmunity as a disease of T-cell/β-cell cross talk will ultimately advance our understanding of type 1 diabetes pathogenesis and improve our chances of preventing or reversing disease progression.

Disrupting the DREAM complex enables proliferation of adult human pancreatic β cells

Resistance to regeneration of insulin-producing pancreatic β cells is a fundamental challenge for type 1 and type 2 diabetes. Recently, small molecule inhibitors of the kinase DYRK1A have proven effective in inducing adult human β cells to proliferate, but their detailed mechanism of action is incompletely understood. We interrogated our human insulinoma and β cell transcriptomic databases seeking to understand why β cells in insulinomas proliferate, while normal β cells do not. This search reveals the DREAM complex as a central regulator of quiescence in human β cells. The DREAM complex consists of a module of transcriptionally repressive proteins that assemble in response to DYRK1A kinase activity, thereby inducing and maintaining cellular quiescence. In the absence of DYRK1A, DREAM subunits reassemble into the pro-proliferative MMB complex. Here, we demonstrate that small molecule DYRK1A inhibitors induce human β cells to replicate by converting the repressive DREAM complex to its pro-proliferative MMB conformation.

Oral delivery of the intracellular domain of the insulinoma-associated protein 2 (IA-2ic) by bacterium-like particles (BLPs) prevents type 1 diabetes mellitus in NOD mice

Antigen-specific immune tolerance, which possesses great potential in preventing or curing type 1 diabetes mellitus (T1DM), can be induced by oral vaccination with T1DM-related autoantigens. However, direct administration of autoantigens via oral route exhibits a low tolerance-inducing effect as a result of the digestion of protein antigens in the gastrointestinal tract (GIT) and therefore, a large dosage of autoantigens may be needed. In this study, bacterium-like particles (BLPs) made from food-grade lactic acid bacteria were used to deliver the intracellular domain of the insulinoma-associated protein 2 (IA-2ic). For this purpose, BLPs-IA-2ic vaccine in which IA-2ic bound to the surface of BLPs was constructed. BLPs enhanced the stability of the delivered IA-2ic based on the stability analysis in vitro. Oral administration of BLPs-IA-2ic significantly reduced T1DM incidence in NOD mice. The mice fed BLPs-IA-2ic exhibited a significant reduction in insulitis and preserved the ability to secrete insulin. Immunologic analysis showed that oral vaccination with BLPs-IA-2ic induced antigen-specific T cell tolerance. The results revealed that the successful induction of immune tolerance was dependent on the immune deviation (in favor of T helper 2 responses) and CD4⁺CD25⁺FoxP3⁺ regulatory T cells. Hence, oral vaccination with BLPs-IA-2ic shows potential for application in preventing T1DM.

Self-Antigens Targeted by Regulatory T Cells in Type 1 Diabetes

While progress has been made toward understanding mechanisms that lead to the development of autoimmunity, there is less knowledge regarding protective mechanisms from developing such diseases. For example, in type 1 diabetes (T1D), the immune-mediated form of diabetes, the role of pathogenic T cells in the destruction of pancreatic islets is well characterized, but immune-mediated mechanisms that contribute to T1D protection have not been fully elucidated. One potential protective mechanism includes the suppression of immune responses by regulatory CD4 T cells (Tregs) that recognize self-peptides from islets presented by human leukocyte antigen (HLA) class II molecules. In this review, we summarize what is known about the antigenic self-peptides recognized by Tregs in the context of T1D.