Insulinoma-released exosomes activate autoreactive marginal zone-like B cells that expand endogenously in prediabetic NOD mice

A Targeted Deep Sequencing Method to Quantify Endogenous Retrovirus Gag Sequence Variants and Open Reading Frames Expressed in Nonobese Diabetic Mice

Endogenous retroviruses (ERVs) are involved in autoimmune diseases such as type 1 diabetes (T1D). ERV gene products homologous to murine leukemia retroviruses are expressed in the pancreatic islets of NOD mice, a model of T1D. One ERV gene, Gag, with partial or complete open reading frames (ORFs), is detected in the islets, and it contains many sequence variants. An amplicon deep sequencing analysis was established by targeting a conserved region within the Gag gene to compare NOD with T1D-resistant mice or different ages of prediabetic NOD mice. We observed that the numbers of different Gag variants and ORFs are linked to T1D susceptibility. More importantly, these numbers change during the course of diabetes development and can be quantified to calculate the levels of disease progression. Sequence alignment analysis led to identification of additional markers, including nucleotide mismatching and amino acid consensus at specific positions that can distinguish the early and late stages, before diabetes onset. Therefore, the expression of sequence variants and ORFs of ERV genes, particularly Gag, can be quantified as biomarkers to estimate T1D susceptibility and disease progression.

How does exosome cause diabetes?

Exosomes are extracellular vesicles that are widely distributed in multiple cell types and circulating body fluids. They have a specific effect on the target cells by releasing different vesicle contents. They have recently been recognized as important means of intercellular communication, being involved, for example, in the development of diabetes by increasing β-cell apoptosis, activating autoimmunity, and regulating cytokines to affect islet β-cell function and insulin sensitivity. An in-depth study of the role of exosome in the pathogenesis of diabetes may therefore provide a novel means of diagnosing and treating diabetes. In this review, we detail how exosome is involved in the development of diabetes.

Exosomes; a Potential Source of Biomarkers, Therapy, and Cure for Type-1 Diabetes

The scourge of type-1 diabetes (T1D) is the morbidity and mortality it and its complications cause at a younger age. This propels the constant search for better diagnostic, treatment, and management strategies, with the ultimate quest being a cure for T1D. Recently, the therapeutic potential of exosomes has generated a lot of interest. Among the characteristics of exosomes of particular interest are (a) their regenerative capacity, which depends on their "origin", and (b) their "content", which determines the cell communication and crosstalk they influence. Other functional capacities, including paracrine and endocrine homeostatic regulation, pathogenic response ability resulting in insulin secretory defects or β-cell death under normal metabolic conditions, immunomodulation, and promotion of regeneration, have also garnered significant interest. Exosome "specificity" makes them suitable as biomarkers or predictors, and their "mobility" and "content" lend credence to drug delivery and therapeutic suitability. This review aims to highlight the functional capacities of exosomes and their established as well as novel contributions at various pathways in the onset and progression of T1D. The pathogenesis of T1D involves a complex crosstalk between insulin-secreting pancreatic β-cells and immune cells, which is partially mediated by exosomes. We also examine the potential implications for type 2 diabetes (T2D), as the link in T2D has guided T1D exploration. The collective landscape presented is expected to help identify how a deeper understanding of exosomes (and their cargo) can provide a framework for actionable solutions to prevent, halt, or change the very course of T1D and its complications.

β Cell microRNAs Function as Molecular Hubs of Type 1 Diabetes Pathogenesis and as Biomarkers of Diabetes Risk

MicroRNAs (miRNAs) are small non-coding RNAs that play a crucial role in modulating gene expression and are enriched in cell-derived extracellular vesicles (EVs). We investigated whether miRNAs from human islets and islet-derived EVs could provide insight into β cell stress pathways activated during type 1 diabetes (T1D) evolution, therefore serving as potential disease biomarkers. We treated human islets from 10 cadaveric donors with IL-1β and IFN-γ to model T1D ex vivo. MicroRNAs were isolated from islets and islet-derived EVs, and small RNA sequencing was performed. We found 20 and 14 differentially expressed (DE) miRNAs in cytokine- versus control-treated islets and EVs, respectively. Interestingly, the miRNAs found in EVs were mostly different from those found in islets. Only two miRNAs, miR-155-5p and miR-146a-5p, were upregulated in both islets and EVs, suggesting selective sorting of miRNAs into EVs. We used machine learning algorithms to rank DE EV-associated miRNAs, and developed custom label-free Localized Surface Plasmon Resonance-based biosensors to measure top ranked EVs in human plasma. Results from this analysis revealed that miR-155, miR-146, miR-30c, and miR-802 were upregulated and miR-124-3p was downregulated in plasma-derived EVs from children with recent-onset T1D. In addition, miR-146 and miR-30c were upregulated in plasma-derived EVs of autoantibody positive (AAb+) children compared to matched non-diabetic controls, while miR-124 was downregulated in both T1D and AAb+ groups. Furthermore, single-molecule fluorescence in situ hybridization confirmed increased expression of the most highly upregulated islet miRNA, miR-155, in pancreatic sections from organ donors with AAb+ and T1D.

Extracellular vesicles as personalized medicine

Extracellular vesicles (EVs) are released from all cells in the body, forming an important intercellular communication network that contributes to health and disease. The contents of EVs are cell source-specific, inducing distinct signaling responses in recipient cells. The specificity of EVs and their accumulation in fluid spaces that are accessible for liquid biopsies make them highly attractive as potential biomarkers and therapies for disease. The duality of EVs as favorable (therapeutic) or unfavorable (pathological) messengers is context dependent and remains to be fully determined in homeostasis and various disease states. This review describes the use of EVs as biomarkers, drug delivery vehicles, and regenerative therapeutics, highlighting examples involving viral infections, cancer, and neurological diseases. There is growing interest to provide personalized therapy based on individual patient and disease characteristics. Increasing evidence suggests that EV biomarkers and therapeutic approaches are ideal for personalized medicine due to the diversity and multifunctionality of EVs.

Extracellular Vesicles and Their Emerging Roles as Cellular Messengers in Endocrinology: An Endocrine Society Scientific Statement

During the last decade, there has been great interest in elucidating the biological role of extracellular vesicles (EVs), particularly, their hormone-like role in cell-to-cell communication. The field of endocrinology is uniquely placed to provide insight into the functions of EVs, which are secreted from all cells into biological fluids and carry endocrine signals to engage in paracellular and distal interactions. EVs are a heterogeneous population of membrane-bound vesicles of varying size, content, and bioactivity. EVs are specifically packaged with signaling molecules, including lipids, proteins, and nucleic acids, and are released via exocytosis into biofluid compartments. EVs regulate the activity of both proximal and distal target cells, including translational activity, metabolism, growth, and development. As such, EVs signaling represents an integral pathway mediating intercellular communication. Moreover, as the content of EVs is cell-type specific, it is a "fingerprint" of the releasing cell and its metabolic status. Recently, changes in the profile of EV and bioactivity have been described in several endocrine-related conditions including diabetes, obesity, cardiovascular diseases, and cancer. The goal of this statement is to highlight relevant aspects of EV research and their potential role in the field of endocrinology.

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

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

Extracellular Vesicles in Type 1 Diabetes: A Versatile Tool

Type 1 diabetes is a chronic autoimmune disease affecting nearly 35 million people. This disease develops as T-cells continually attack the β-cells of the islets of Langerhans in the pancreas, which leads to β-cell death, and steadily decreasing secretion of insulin. Lowered levels of insulin minimize the uptake of glucose into cells, thus putting the body in a hyperglycemic state. Despite significant progress in the understanding of the pathophysiology of this disease, there is a need for novel developments in the diagnostics and management of type 1 diabetes. Extracellular vesicles (EVs) are lipid-bound nanoparticles that contain diverse content from their cell of origin and can be used as a biomarker for both the onset of diabetes and transplantation rejection. Furthermore, vesicles can be loaded with therapeutic cargo and delivered in conjunction with a transplant to increase cell survival and long-term outcomes. Crucially, several studies have linked EVs and their cargos to the progression of type 1 diabetes. As a result, gaining a better understanding of EVs would help researchers better comprehend the utility of EVs in regulating and understanding type 1 diabetes. EVs are a composition of biologically active components such as nucleic acids, proteins, metabolites, and lipids that can be transported to particular cells/tissues through the blood system. Through their varied content, EVs can serve as a flexible aid in the diagnosis and management of type 1 diabetes. In this review, we provide an overview of existing knowledge about EVs. We also cover the role of EVs in the pathogenesis, detection, and treatment of type 1 diabetes and the function of EVs in pancreas and islet β-cell transplantation.

In sickness and in health: The functional role of extracellular vesicles in physiology and pathology in vivo: Part II: Pathology: Part II: Pathology

It is clear from Part I of this series that extracellular vesicles (EVs) play a critical role in maintaining the homeostasis of most, if not all, normal physiological systems. However, the majority of our knowledge about EV signalling has come from studying them in disease. Indeed, EVs have consistently been associated with propagating disease pathophysiology. The analysis of EVs in biofluids, obtained in the clinic, has been an essential of the work to improve our understanding of their role in disease. However, to interfere with EV signalling for therapeutic gain, a more fundamental understanding of the mechanisms by which they contribute to pathogenic processes is required. Only by discovering how the EV populations in different biofluids change-size, number, and physicochemical composition-in clinical samples, may we then begin to unravel their functional roles in translational models in vitro and in vivo, which can then feedback to the clinic. In Part II of this review series, the functional role of EVs in pathology and disease will be discussed, with a focus on in vivo evidence and their potential to be used as both biomarkers and points of therapeutic intervention.

Sustained high glucose intake accelerates type 1 diabetes in NOD mice

INTRODUCTION

Epidemiological studies have suggested that dietary factors, especially high consumption of high glycaemic index carbohydrates and sugars, may trigger or exacerbate the progression of type 1 diabetes. We aimed to provide experimental evidence to confirm this relevance and to explore the underlying mechanisms.

METHODS

NOD mice were given sustained high-glucose drinking or glucose-free water and observed for the incidence of type 1 diabetes and islet inflammation. RNAseq was performed to detect the transcriptome changes of the NOD islet beta cell line NIT-1 after high glucose treatment, and mass spectrometry was performed to detect the proteome changes of NIT-1-cells-derived sEVs.

RESULTS

Sustained high glucose drinking significantly aggravates islet inflammation and accelerates the onset of type 1 diabetes in NOD mice. Mechanistically, high glucose treatment induces aberrant ER stress and up-regulates the expression of autoantigens in islet beta cell. Moreover, high glucose treatment alters the proteome of beta-cells-derived sEVs, and significantly enhances the ability of sEVs to promote DC maturation and stimulate immune inflammatory response.

DISCUSSION

This study provides evidence for negative effect of high glucose intake as a dietary factor on the pathogenesis of type 1 diabetes in genetically predisposed individuals. Therefore, avoiding high sugar intake may be an effective disease prevention strategy for children or adults susceptible to type 1 diabetes.

Targeting the microRNAs in exosome: A potential therapeutic strategy for alleviation of diabetes-related cardiovascular complication

Diabetes-related cardiovascular disease (CVD) is a global health issue that causes thousands of people's death around the world annually. Diabetes-related CVD is still prevailing despite the progression being made in its diagnosis and treatment. Therefore it is urgent to find therapeutic strategies.to prevent it. MicroRNA (miRNA) is a single-stranded non-coding RNA involved in the process of post-transcriptional control of gene expression in eukaryotes. A large number of literatures reveal that miRNAs are implicated in diabetes-related CVD. The increase of miRNAs in exosomes may promote the occurrence and development of diabetes-related cardiovascular complication. However, some other studies identify that miRNAs in exosomes are supposed to be involved in cardiac regeneration and confer cardiac protection effect. Therefore, targeting the miRNA in exosome is regarded as a potent therapeutic measure to alleviate diabetes-related CVD. In this article, we review current knowledge about the role of exosomal miRNAs in diabetes-related cardiovascular complication, such as coronary heart disease, Peripheral artery disease, stroke, diabetic cardiomyopathy, diabetic nephropathy and diabetic retinopathy. Exosomal miRNAs are considered to be central regulators of diabetes-Related CVD and provide a therapeutic tool for diagnosis and treatment of diabetes-related cardiovascular complication.

Pro-inflammatory β cell small extracellular vesicles induce β cell failure through activation of the CXCL10/CXCR3 axis in diabetes

Coordinated communication among pancreatic islet cells is necessary for maintenance of glucose homeostasis. In diabetes, chronic exposure to pro-inflammatory cytokines has been shown to perturb β cell communication and function. Compelling evidence has implicated extracellular vesicles (EVs) in modulating physiological and pathological responses to β cell stress. We report that pro-inflammatory β cell small EVs (cytokine-exposed EVs [cytoEVs]) induce β cell dysfunction, promote a pro-inflammatory islet transcriptome, and enhance recruitment of CD8+ T cells and macrophages. Proteomic analysis of cytoEVs shows enrichment of the chemokine CXCL10, with surface topological analysis depicting CXCL10 as membrane bound on cytoEVs to facilitate direct binding to CXCR3 receptors on the surface of β cells. CXCR3 receptor inhibition reduced CXCL10-cytoEV binding and attenuated β cell dysfunction, inflammatory gene expression, and leukocyte recruitment to islets. This work implies a significant role of pro-inflammatory β cell-derived small EVs in modulating β cell function, global gene expression, and antigen presentation through activation of the CXCL10/CXCR3 axis.

Marginal zone B cells: From housekeeping function to autoimmunity?

Marginal zone (MZ) B cells comprise a subset of innate-like B cells found predominantly in the spleen, but also in lymph nodes and blood. Their principal functions are participation in quick responses to blood-borne pathogens and secretion of natural antibodies. The latter is important for housekeeping functions such as clearance of apoptotic cell debris. MZ B cells have B cell receptors with low poly-/self-reactivity, but they are not pathogenic at steady state. However, if simultaneously stimulated with self-antigen and pathogen- and/or damage-associated molecular patterns (PAMPs/DAMPs), MZ B cells may participate in the initial steps towards breakage of immunological tolerance. This review summarizes what is known about the role of MZ B cells in autoimmunity, both in mouse models and human disease. We cover factors important for shaping the MZ B cell compartment, how the functional properties of MZ B cells may contribute to breaking tolerance, and how MZ B cells are being regulated.

The Role of Extracellular Vesicles in the Pathogenesis and Treatment of Autoimmune Disorders

Extracellular vesicles (EVs) are important players in autoimmune diseases, both in disease pathogenesis and as potential treatments. EVs can transport autoimmune triggers throughout the body, facilitating the process of antigen presentation. Understanding the link between cellular stress and EV biogenesis and intercellular trafficking will advance our understanding of autoimmune diseases. In addition, EVs can also be effective treatments for autoimmune diseases. The diversity of cell types that produce EVs leads to a wide range of molecules to be present in EVs, and thus EVs have a wide range of physiological effects. EVs derived from dendritic cells or mesenchymal stem cells have been shown to reduce inflammation. Since many autoimmune treatments are focused only on symptom management, EVs present a promising avenue for potential treatments. This review looks at the different roles EVs can play in autoimmune diseases, from disease pathology to diagnosis and treatment. We also overview various methodologies in isolating or generating EVs and look to the future for possible applications of EVs in autoimmune diseases.

Exosomes from β-Cells Promote Differentiation of Induced Pluripotent Stem Cells into Insulin-Producing Cells Through microRNA-Dependent Mechanisms

OBJECTIVE

Exosomes have emerged as potential tools for the differentiation of induced pluripotent stem cells (iPSCs) into insulin-producing cells (IPCs). Exosomal microRNAs are receiving increasing attention in this process. Here, we aimed at investigating the role of exosomes derived from a murine pancreatic β-cell line and identifying signature exosomal miRNAs on iPSCs differentiation.

METHODS

Exosomes were isolated from MIN6 cells and identified with TEM, NTA and Western blot. PKH67 tracer and transwell assay were used to confirm exosome delivery into iPSCs. qRT-PCR was applied to detect key pancreatic transcription gene expression and exosome-derived miRNA expression. Insulin secretion was determined using FCM and immunofluorescence. The specific exosomal miRNAs were determined via RNA-interference of Ago2. The therapeutic effect of 21 day-exosome-induced IPCs was validated in T1D mice induced by STZ.

RESULTS

iPSCs cultured in medium containing exosomes showed sustained higher expression of MAFA, Insulin1, Insulin2, Isl1, Neuroud1, Nkx6.1 and NGN3 compared to control iPSCs. In FCM analysis, approximately 52.7% of the differentiated cells displayed insulin expression at the middle stage. Consistent with the gene expression data, immunofluorescence assays showed that Nkx6.1 and insulin expression in iPSCs were significantly upregulated. Intriguingly, the expression of pancreatic markers and insulin was significantly decreased in iPSCs cultured with siAgo2 exosomes. Transplantation of 21 day-induced IPCs intoT1D mice efficiently enhanced glucose tolerance and partially controlled hyperglycemia. The therapeutic effect was significantly attenuated in T1D mice that received iPSCs cultured with siAgo2 exosomes. Of the seven exosomal microRNAs selected for validation, miR-706, miR-709, miR-466c-5p, and miR-423-5p showed dynamic expression during 21 days in culture.

CONCLUSION

These data indicate that differentiation of exosome-induced iPSCs into functional cells is crucially dependent on the specific miRNAs encased within exosomes, whose functional analysis is likely to provide insight into novel regulatory mechanisms governing iPSCs differentiation into IPCs.

Expression of miRNA-29 in Pancreatic β Cells Promotes Inflammation and Diabetes via TRAF3

Type 2 diabetes mellitus (T2DM) is recognized as a chronic, low-grade inflammatory disease characterized by insulin resistance and pancreatic β cell dysfunction; however, the underlying molecular mechanism remains unclear. Here, we report a key β cell-macrophage crosstalk pathway mediated by the miRNA-29-TNF-receptor-associated factor 3 (TRAF3) axis. β cell-specific transgenic miR-29a/b/c mice are predisposed to develop glucose intolerance and insulin resistance when fed a high-fat diet (HFD). The metabolic effect of β cell miR-29 is largely mediated through macrophages because either depletion of macrophages or reconstitution with miR-29-signaling defective bone marrow improves metabolic parameters in the transgenic mice. Mechanistically, our data show that miR-29 promotes the recruitment and activation of circulating monocytes and macrophages and, hence, inflammation, via miR-29 exosomes in a TRAF3-dependent manner. Our results demonstrate the ability of β cells to modulate the systemic inflammatory tone and glucose homeostasis via miR-29 in response to nutrient overload.

Emerging Roles of Exosomes in T1DM

Type 1 diabetes mellitus (T1DM) is a complex autoimmune disorder that mainly affects children and adolescents. The elevated blood glucose level of patients with T1DM results from absolute insulin deficiency and leads to hyperglycemia and the development of life-threatening diabetic complications. Although great efforts have been made to elucidate the pathogenesis of this disease, the precise underlying mechanisms are still obscure. Emerging evidence indicates that small extracellular vesicles, namely, exosomes, take part in intercellular communication and regulate interorgan crosstalk. More importantly, many findings suggest that exosomes and their cargo are associated with the development of T1DM. Therefore, a deeper understanding of exosomes is beneficial for further elucidating the pathogenic process of T1DM. Exosomes are promising biomarkers for evaluating the risk of developingty T1DM, monitoring the disease state and predicting related complications because their number and composition can reflect the status of their parent cells. Additionally, since exosomes are natural carriers of functional proteins, RNA and DNA, they can be used as therapeutic tools to deliver these molecules and drugs. In this review, we briefly introduce the current understanding of exosomes. Next, we focus on the relationship between exosomes and T1DM from three perspectives, i.e., the pathogenic role of exosomes in T1DM, exosomes as novel biomarkers of T1DM and exosomes as therapeutic tools for T1DM.

Exosomal miR-22-3p Derived from Chronic Rhinosinusitis with Nasal Polyps Regulates Vascular Permeability by Targeting VE-Cadherin

Background

The abnormal vascular permeability is associated with the formation of chronic rhinosinusitis with nasal polyps (CRSwNP). Previously, our study demonstrated that the nasal lavage fluid- (NLF-) derived exosomes from CRSwNP can promote the vascular permeability of human umbilical vein endothelial cells (HUVECs). miR-22-3p, a specific differentiated miRNA, is reported to regulate microvessels in some diseases. This study is purposed to explore the impact of exosomal miR-22-3p derived from CRSwNP on vascular permeability and identify the underlying targets.

Methods

Exosomes were extracted from NLF of 26 CRSwNP patients and 10 control patients. Quantitative real-time PCR (qRT- PCR) was applied to evaluate the relative level of exosomal miR-22-3p. The impact of exosomal miR-22-3p on HUVECs was assessed by permeability assays in vitro. The potential molecular targets of miR-22-3p were investigated by applying such technologies as dual-luciferase reporter assay and western blot.

Results

miR-22-3p was upregulated in NLF-derived exosomes from CRSwNP. Exosomal miR-22-3p derived from CRSwNP enhanced the tubule permeability of HUVECs. Vascular endothelial- (VE-) cadherin (CDH5) was identified as a direct target of miR-22-3p. miR-22-3p regulated the vascular permeability by targeting VE-cadherin in HUVECs.

Conclusions

Exosomal miR-22-3p derived from NLF of CRSwNP plays an important role in regulating vascular permeability by targeting VE-cadherin.

Network Pharmacology Combined with Transcriptional Analysis to Unveil the Biological Basis of Astaxanthin in Reducing the Oxidative Stress Induced by Diabetes Mellitus

PURPOSE

Astaxanthin (Ast) has been reported to reduce oxidative stress induced by diabetes mellitus (DM). The aim of this research was to give a systematic overview of the biological basis for this process.

METHODS

Ast-targeted proteins were collected from the BATMAN database, Comparative Toxicogenomics Database, and STITCH database. Putative DM-related protein targets were collected from the GeneCards database. A DM-rat model was then built with streptozotocin (STZ) combined with a high-sugar, high-fat diet for 30 days. Total cholesterol (TC), triglycerides (TGs), and insulin levels were examined using whole tail-vein blood from overnight-fasted rats. SOD, GSH, and MDA activy was detected in liver tissue (p<0.05). In addition, we used RNA-sequencing analysis to detect gene-transcription level in liver tissue of rats and GO biological process analysis to show all the log2FC≥2 genes in the Ast-fed DM rats compared with the DM group using the STRING database. Ast-intersecting targets were collected with Venn analysis. Docking analysis between Ast and targeted proteins was down with the SwissDock server. Ast targets-pathway networks were built using Cytoscape 3.7.2 software.

RESULTS

A total of 120 Ast-targeted proteins and 13,784 DM-related targets were collected. Ast functioned in reducing TC, TG, and MDA levels, promoting SOD activity and GSH expression, and alleviating islet-cell injury in Ast-fed DM rats compared with DM control rats. Furthermore, genes involved in MAPK, TNF, AMPK, and FOXO signaling pathways were differently expressed in Ast-treated DM rats compared with DM rats. The differentially expressed genes were enriched in euchromatin, thyroid cancer, and metaphase-plate congression. Three Ast-intersecting targets - Col5A1, Nqo1, and Notch2 - were then identified. We found possible binding patterns of Ast with Nqo1 and Notch2, respectively. Ast targets-pathway networks were finally built to show a systematic overview of how Ast works in multiple pathways to reduce oxidative stress. Taken together, Ast is predicted to target Col5A1, Nqo1, and Notch2 to form a network of systemic pharmacological effects to: 1) promote insulin-releasing balance and relieve insulin resistance, 2) reduce testicular cell apoptosis, and 3) maintain normal size in marginal-zone B cells and inhibit autoimmune DM, all of which contribute to the balance of lipid metabolism and reduction of oxidative stress in DM patients.

CONCLUSION

Ast functions in reducing oxidative stress in DM rats by regulating a variety of targets to form a comprehensive antioxidative network.

Molecular and Functional Diversity of Distinct Subpopulations of the Stressed Insulin-Secreting Cell's Vesiculome

Beta cell failure and apoptosis following islet inflammation have been associated with autoimmune type 1 diabetes pathogenesis. As conveyors of biological active material, extracellular vesicles (EV) act as mediators in communication with immune effectors fostering the idea that EV from inflamed beta cells may contribute to autoimmunity. Evidence accumulates that beta exosomes promote diabetogenic responses, but relative contributions of larger vesicles as well as variations in the composition of the beta cell's vesiculome due to environmental changes have not been explored yet. Here, we made side-by-side comparisons of the phenotype and function of apoptotic bodies (AB), microvesicles (MV) and small EV (sEV) isolated from an equal amount of MIN6 beta cells exposed to inflammatory, hypoxic or genotoxic stressors. Under normal conditions, large vesicles represent 93% of the volume, but only 2% of the number of the vesicles. Our data reveal a consistently higher release of AB and sEV and to a lesser extent of MV, exclusively under inflammatory conditions commensurate with a 4-fold increase in the total volume of the vesiculome and enhanced export of immune-stimulatory material including the autoantigen insulin, microRNA, and cytokines. Whilst inflammation does not change the concentration of insulin inside the EV, specific Toll-like receptor-binding microRNA sequences preferentially partition into sEV. Exposure to inflammatory stress engenders drastic increases in the expression of monocyte chemoattractant protein 1 in all EV and of interleukin-27 solely in AB suggesting selective sorting toward EV subspecies. Functional in vitro assays in mouse dendritic cells and macrophages reveal further differences in the aptitude of EV to modulate expression of cytokines and maturation markers. These findings highlight the different quantitative and qualitative imprints of environmental changes in subpopulations of beta EV that may contribute to the spread of inflammation and sustained immune cell recruitment at the inception of the (auto-) immune response.

The potential roles of exosomes in pancreatic cancer initiation and metastasis

Pancreatic cancer (PaCa) is an insidious and highly metastatic malignancy, with a 5-year survival rate of less than 5%. So far, the pathogenesis and progression mechanisms of PaCa have been poorly characterized. Exosomes correspond to a class of extracellular nanovesicles, produced by a broad range of human somatic and cancerous cells. These particular nanovesicles are mainly composed by proteins, genetic substances and lipids, which mediate signal transduction and material transport. A large number of studies have indicated that exosomes may play decisive roles in the occurrence and metastatic progression of PaCa. This article summarizes the specific functions of exosomes and their underlying molecular mechanisms in mediating the initiation and metastatic capability of PaCa.

Roles of Noncoding RNAs in Islet Biology

The discovery that most mammalian genome sequences are transcribed to ribonucleic acids (RNA) has revolutionized our understanding of the mechanisms governing key cellular processes and of the causes of human diseases, including diabetes mellitus. Pancreatic islet cells were found to contain thousands of noncoding RNAs (ncRNAs), including micro-RNAs (miRNAs), PIWI-associated RNAs, small nucleolar RNAs, tRNA-derived fragments, long non-coding RNAs, and circular RNAs. While the involvement of miRNAs in islet function and in the etiology of diabetes is now well documented, there is emerging evidence indicating that other classes of ncRNAs are also participating in different aspects of islet physiology. The aim of this article will be to provide a comprehensive and updated view of the studies carried out in human samples and rodent models over the past 15 years on the role of ncRNAs in the control of α- and β-cell development and function and to highlight the recent discoveries in the field. We not only describe the role of ncRNAs in the control of insulin and glucagon secretion but also address the contribution of these regulatory molecules in the proliferation and survival of islet cells under physiological and pathological conditions. It is now well established that most cells release part of their ncRNAs inside small extracellular vesicles, allowing the delivery of genetic material to neighboring or distantly located target cells. The role of these secreted RNAs in cell-to-cell communication between β-cells and other metabolic tissues as well as their potential use as diabetes biomarkers will be discussed. © 2020 American Physiological Society. Compr Physiol 10:893-932, 2020.

Chicken-or-egg question: Which came first, extracellular vesicles or autoimmune diseases?

Extracellular vesicles (EVs) have attracted great interest as contributors to autoimmune disease (AD) pathogenesis, owing to their immunomodulatory potential; they may also play a role in triggering tolerance disruption, by delivering auto‐antigens. EVs are released by almost all cell types, and afford paracrine or distal cell communication, functioning as biological carriers of active molecules including lipids, proteins, and nucleic acids. Depending on stimuli from the external microenvironment or on their cargo, EVs can promote or suppress immune responses. ADs are triggered by inappropriate immune‐system activation against the self, but their precise etiology is still poorly understood. Accumulating evidence indicates that lifestyle and diet have a strong impact on their clinical onset and development. However, to date the mechanisms underlying AD pathogenesis are not fully clarified, and reliable markers, which would provide early prediction and disease progression monitoring, are lacking. In this connection, EVs have recently been indicated as a promising source of AD biomarkers. Although EV isolation is currently based on differential centrifugation or density‐gradient ultracentrifugation, the resulting co‐isolation of contaminants (i.e., protein aggregates), and the pooling of all EVs in one sample, limit this approach to abundantly‐expressed EVs. Flow cytometry is one of the most promising methods for detecting EVs as biomarkers, and may have diagnostic applications. Furthermore, very recent findings describe a new method for identifying and sorting EVs by flow cytometry from freshly collected body fluids, based on specific EV surface markers.

The Role of Extracellular Vesicles in β-Cell Function and Viability: A Scoping Review

Extracellular vesicles (EVs) released by cells throughout the body have been implicated in diabetes pathogenesis. Understanding the role of EVs in regulation of β-cell function and viability may provide insights into diabetes etiology and may lead to the development of more effective screening and diagnostic tools to detect diabetes earlier and prevent disease progression. This review was conducted to determine what is known from the literature about the effect of EV crosstalk on pancreatic β-cell function and viability in the pathogenesis of diabetes mellitus, to perform a gap analysis for future research directions, and to discuss implications of available evidence for diabetes care. The literature search yielded 380 studies from which 31 studies were determined to meet eligibility criteria. The majority of studies had the disease context of autoimmunity in T1DM. The most commonly studied EV crosstalk dynamics involved localized EV-mediated communication between β-cells and other islet cells, or between β-cells and immune cells. Other organs and tissues secreting EVs that affect β-cells include skeletal muscle, hepatocytes, adipocytes, immune cells, bone marrow, vascular endothelium, and mesenchymal stem cells. Characterization of EV cargo molecules with regulatory effects in β-cells was conducted in 24 studies, with primary focus on microRNA cargo. Gaps identified included scarcity of evidence for the effect on β-cell function and viability of EVs from major metabolic organs/tissues such as muscle, liver, and adipose depots. Future research should address these gaps as well as characterize a broader range of EV cargo molecules and their activity in β-cells.

Extracellular Vesicles in Type 1 Diabetes: Messengers and Regulators

PURPOSE OF REVIEW

Theories about the pathogenesis of type 1 diabetes (T1D) refer to the potential of primary islet inflammatory signaling as a trigger for the loss of self-tolerance leading to disease onset. Emerging evidence suggests that extracellular vesicles (EV) may represent the missing link between inflammation and autoimmunity. Here, we review the evidence for a role of EV in the pathogenesis of T1D, as well as discuss their potential value in the clinical sphere, as biomarkers and therapeutic agents.

RECENT FINDINGS

EV derived from β cells are enriched in diabetogenic autoantigens and miRNAs that are selectively sorted and packaged. These EV play a pivotal role in antigen presentation and cell to cell communication leading to activation of autoimmune responses. Furthermore, recent evidence suggests the potential of EV as novel tools in clinical diagnostics and therapeutic interventions. In-depth analysis of EV cargo using modern multi-parametric technologies may be useful in enhancing our understanding of EV-mediated immune mechanisms and in identifying robust biomarkers and therapeutic strategies for T1D.

Exosomes and diabetes

Diabetes is a group of metabolic diseases characterized by elevated blood glucose levels that drive the development of life-threatening complications. Diabetes results from a situation of insufficient insulin action, either by deficient production of the hormone by the pancreas, or by the development of insulin resistance in peripheral tissues such as liver, muscle, or the adipose depots. Communication between organs is thus central to the maintenance of glucose homoeostasis. Recently, several studies are evidencing that small vesicles called exosomes released by, amongst other, the adipose tissue can regulate gene expression in other tissues, hence modulating interorgan crosstalk. Therefore, exosomes participate in the development of diabetes and its associated complications. Their study holds the potential of providing us with novel biomarkers for the early diagnosis and stratification of patients at risk of developing diabetes, hence allowing the timely implementation of more personalized therapies. On the other hand, the molecular dissection of the pathways initiated by exosomes under situations of metabolic stress could help to gain a deeper knowledge of the pathophysiology of diabetes and its associated metabolic diseases.

Lymphocyte-Derived Exosomal MicroRNAs Promote Pancreatic β Cell Death and May Contribute to Type 1 Diabetes Development

Type 1 diabetes is an autoimmune disease initiated by the invasion of pancreatic islets by immune cells that selectively kill the β cells. We found that rodent and human T lymphocytes release exosomes containing the microRNAs (miRNAs) miR-142-3p, miR-142-5p, and miR-155, which can be transferred in active form to β cells favoring apoptosis. Inactivation of these miRNAs in recipient β cells prevents exosome-mediated apoptosis and protects non-obese diabetic (NOD) mice from diabetes development. Islets from protected NOD mice display higher insulin levels, lower insulitis scores, and reduced inflammation. Looking at the mechanisms underlying exosome action, we found that T lymphocyte exosomes trigger apoptosis and the expression of genes involved in chemokine signaling, including Ccl2, Ccl7, and Cxcl10, exclusively in β cells. The induction of these genes may promote the recruitment of immune cells and exacerbate β cell death during the autoimmune attack. Our data point to exosomal-miRNA transfer as a communication mode between immune and insulin-secreting cells.

Immune Response to Extracellular Vesicles From Human Islets of Langerhans in Patients With Type 1 Diabetes

The autoimmune response that characterizes type 1 diabetes (T1D) has no clear cause. Extracellular vesicles (EVs) play an important role in triggering the immune response in other contexts. Here, we propose a model by which EVs isolated from human islets stimulate proinflammatory immune responses and lead to peripheral blood mononuclear cell (PBMC) activation. We show that human islet EVs are internalized by monocytes and B cells and lead to an increase in T-helper 1, 2, and 17 cytokine expression, as well as T and B cell proliferation. Importantly, we demonstrate memory T and B cell activation by EVs selectively in PBMCs of patients with T1D. Additionally, human islet EVs induce an increase in antibodies against glutamic acid decarboxylase 65 (GAD65) in T1D PBMCs. Furthermore, pretreatment of T1D PBMCs with ibrutinib, an inhibitor of Bruton tyrosine kinase, dampens EV-induced memory B cell activation and GAD65 antibody production. Collectively, our findings indicate a role for human islet EVs in mediating activation of B and T cells and GAD65 autoantibody production.

A disintegrin and metalloprotease 10-containing exosomes derived from nasal polyps promote angiogenesis and vascular permeability

Abnormal angiogenesis and vascular permeability is important for the formation of nasal polyps (NPs). Increasing evidence has indicated that exosomes serve a vital role in modulating angiogenesis and vascular permeability. A disintegrin and metalloprotease 10 (ADAM10), an important type of proteinase that is overexpressed in various diseases, can influence angiogenesis and vascular permeability and has been observed in healthy nasal exosomes. To the best of our knowledge, the expression levels and the function of ADAM10 in NLF‑derived exosomes from NPs has not been demonstrated previously. In order to determine the influence of exosomes derived from nasal lavage fluid (NLF) on angiogenesis and vascular permeability, 25 nasal polyp patients and 15 healthy volunteers were enrolled in the present study. NLF was collected from all of the subjects. Exosomes were isolated from NLF, visualized under transmission electron microscope and identified using western blot analysis. The effect of exosomes on human umbilical vein endothelial cells (HUVECs) was measured by tube formation and permeability assays in vitro. The expression of exosomal ADAM10 was also analyzed by western blotting. NLF‑derived exosomes from NPs influenced proliferation, tube formation and the permeability of HUVECs. ADAM10 was highly expressed in NLF‑derived exosomes from NPs when compared with healthy volunteers. Thus, NLF‑derived exosomes from NPs promoted angiogenesis and vascular permeability, which may be associated with abundant ADAM10 in NP exosomes.

Autoimmune Responses to Exosomes and Candidate Antigens Contribute to Type 1 Diabetes in Non-Obese Diabetic Mice

PURPOSE OF REVIEW

The initial autoimmune trigger of type 1 diabetes (T1D) remains unclear. In non-obese diabetic (NOD) mice, islet inflammation starts early in life, suggesting the presence of an endogenous trigger for the spontaneous autoimmune response in this T1D mouse model. In this review, we argue that abnormal release of exosomes might be the trigger of the early inflammatory and autoimmune responses in the islets.

RECENT FINDINGS

Exosomes are nano-sized membrane complexes that are secreted by cells following fusion of late endosomes and/or multivesicular bodies with the plasma membrane. They are known extracellular messengers, communicating among neighboring cells via transporting large molecules from parent cells to recipient cells. Recent evidence demonstrates that these extracellular vesicles can modulate immune responses. It has been shown that insulinoma and islet mesenchymal stem cell-released exosomes are potent immune stimuli that can induce autoreactive B and T cells. Searching for candidate antigens in the exosomes identified endogenous retrovirus (ERV) Env and Gag antigens, which are homologous to an endogenous murine leukemia retrovirus. Autoantibodies and autoreactive T cells spontaneously developed in NOD mice can react to these retroviral antigens. More importantly, expression of the retroviral antigens in the islet mesenchymal stem cells is associated with disease susceptibility, and the expression is restricted to T1D-susceptible but not resistant mouse strains. Exosomes are novel autoimmune targets, carrying autoantigens that can stimulate innate and adaptive immune responses. An abnormal or excess release of exosomes, particularly those ones containing endogenous retroviral antigens might be responsible for triggering tissue-specific inflammatory and autoimmune responses.

Extracellular vesicles from human pancreatic islets suppress human islet amyloid polypeptide amyloid formation

Extracellular vesicles (EVs) are small vesicles released by cells to aid cell-cell communication and tissue homeostasis. Human islet amyloid polypeptide (IAPP) is the major component of amyloid deposits found in pancreatic islets of patients with type 2 diabetes (T2D). IAPP is secreted in conjunction with insulin from pancreatic β cells to regulate glucose metabolism. Here, using a combination of analytical and biophysical methods in vitro, we tested whether EVs isolated from pancreatic islets of healthy patients and patients with T2D modulate IAPP amyloid formation. We discovered that pancreatic EVs from healthy patients reduce IAPP amyloid formation by peptide scavenging, but T2D pancreatic and human serum EVs have no effect. In accordance with these differential effects, the insulin:C-peptide ratio and lipid composition differ between EVs from healthy pancreas and EVs from T2D pancreas and serum. It appears that healthy pancreatic EVs limit IAPP amyloid formation via direct binding as a tissue-specific control mechanism.

Exosomes as new players in metabolic organ cross-talk

Blood glucose homeostasis requires a constant communication between insulin-secreting and insulin-sensitive cells. A wide variety of circulating factors, including hormones, cytokines and chemokines work together to orchestrate the systemic response of metabolic organs to changes in the nutritional state. Failure in the coordination between these organs can lead to a rise in blood glucose levels and to the appearance of metabolic disorders such as diabetes mellitus. Exosomes are small extracellular vesicles (EVs) that are produced via the endosomal pathway and are released from the cells upon fusion of multivesicular bodies with the plasma membrane. There is emerging evidence indicating that these EVs play a central role in cell-to-cell communication. The interest in exosomes exploded when they were found to transport bioactive proteins, messenger RNA (mRNAs) and microRNA (miRNAs) that can be transferred in active form to adjacent cells or to distant organs. In this review, we will first outline the mechanisms governing the biogenesis, the cargo upload and the release of exosomes by donor cells as well as the uptake by recipient cells. We will then summarize the studies that support the novel concept that miRNAs and other exosomal cargo components are new important vehicles for metabolic organ cross-talk.

Presence of diabetes autoantigens in extracellular vesicles derived from human islets

Beta-cell (β-cell) injury is the hallmark of autoimmune diabetes. However, the mechanisms by which autoreactive responses are generated in susceptible individuals are not well understood. Extracellular vesicles (EV) are produced by mammalian cells under normal and stressed physiological states. They are an important part of cellular communication, and may serve a role in antigen processing and presentation. We hypothesized that isolated human islets in culture produce EV that contain diabetes autoantigens (DAA) from these otherwise normal, non-diabetic donors. Here we report the caspase-independent production of EV by human islets in culture, and the characterization of DAA glutamic acid decarboxylase 65 (GAD65) and zinc transporter 8 (ZnT8), as well as the β-cell resident glucose transporter 2 (Glut2), present within the EV.

Type 1 diabetes pathogenesis is modulated by spontaneous autoimmune responses to endogenous retrovirus antigens in NOD mice

Secreted microvesicles (MVs) are potent inflammatory triggers that stimulate autoreactive B and T cells, causing Type 1 Diabetes in non-obese diabetic (NOD) mice. Proteomic analysis of purified MVs released from islet cells detected the presence of endogenous retrovirus (ERV) antigens, including Env and Gag sequences similar to the well-characterized murine leukemia retroviruses. This raises the possibility that ERV antigens may be expressed in the pancreatic islets via MV secretion. Using virus-like particles produced by co-expressing ERV Env and Gag antigens, and a recombinant gp70 Env protein, we demonstrated that NOD but not diabetes-resistant mice developed anti-Env autoantibodies that increase in titer as disease progresses. A lentiviral-based RNA interference knockdown of Gag revealed that Gag contributes to the MV-induced T-cell response, whose diabetogenic function can be demonstrated via cell-transfer into immune-deficient mice. Finally, we observed that Gag and Env are expressed in NOD islet-derived primary mesenchymal stem cells (MSCs). However, MSCs derived from the islets of diabetes-resistant mice do not express the antigens. Taken together, abnormal ERV activation and secretion of MVs may induce anti-retroviral responses to trigger autoimmunity.

Primary Human and Rat β-Cells Release the Intracellular Autoantigens GAD65, IA-2, and Proinsulin in Exosomes Together With Cytokine-Induced Enhancers of Immunity

The target autoantigens in several organ-specific autoimmune diseases, including type 1 diabetes (T1D), are intracellular membrane proteins, whose initial encounter with the immune system is poorly understood. Here we propose a new model for how these proteins can initiate autoimmunity. We found that rat and human pancreatic islets release the intracellular β-cell autoantigens in human T1D, GAD65, IA-2, and proinsulin in exosomes, which are taken up by and activate dendritic cells. Accordingly, the anchoring of GAD65 to exosome-mimetic liposomes strongly boosted antigen presentation and T-cell activation in the context of the human T1D susceptibility haplotype HLA-DR4. Cytokine-induced endoplasmic reticulum stress enhanced exosome secretion by β-cells; induced exosomal release of the immunostimulatory chaperones calreticulin, Gp96, and ORP150; and increased exosomal stimulation of antigen-presenting cells. We propose that stress-induced exosomal release of intracellular autoantigens and immunostimulatory chaperones may play a role in the initiation of autoimmune responses in T1D.

Trehalose prevents aggregation of exosomes and cryodamage

Exosomes are important mediators in intercellular communication. Released by many cell types, they transport proteins, lipids, and nucleic acids to distant recipient cells and contribute to important physiopathological processes. Standard current exosome isolation methods based on differential centrifugation protocols tend to induce aggregation of particles in highly concentrated suspensions and freezing of exosomes can induce damage and inconsistent biological activity. Trehalose is a natural, non-toxic sugar widely used as a protein stabilizer and cryoprotectant by the food and drug industry. Here we report that addition of 25 mM trehalose to pancreatic beta-cell exosome-like vesicle isolation and storage buffer narrows the particle size distribution and increases the number of individual particles per microgram of protein. Repeated freeze-thaw cycles induce an increase in particle concentration and in the width of the size distribution for exosome-like vesicles stored in PBS, but not in PBS 25 mM trehalose. No signs of lysis or incomplete vesicles were observed by cryo-electron tomography in PBS and trehalose samples. In macrophage immune assays, beta-cell extracellular vesicles in trehalose show consistently higher TNF-alpha cytokine secretion stimulation indexes suggesting improved preservation of biological activity. The addition of trehalose might be an attractive means to standardize experiments in the field of exosome research and downstream applications.

Nucleic acid biomarkers of β cell stress and death in type 1 diabetes

PURPOSE OF REVIEW

The purpose of this review is to summarize recent advances in the development of nucleic acid-based biomarkers of type 1 diabetes (T1D).

RECENT FINDINGS

Recent rodent and human studies have identified new roles for stress pathways intrinsic to the β cell during the development of T1D. As such, methods to identify an authentic nucleic acid signature of β cell stress and/or death may improve our ability to predict T1D at earlier timepoints, allowing for optimal timing of immunomodulatory interventions. To this end, both targeted and unbiased approaches have begun to identify changes in microRNA expression patterns in T1D. Moreover, a number of groups have developed distinct assays that quantitatively detect circulating unmethylated insulin DNA, which is thought to primarily emanate from dying β cells.

SUMMARY

Here we highlight unique blood and urine microRNA signatures identified in T1D cohorts, compare differences between first, second, and third-generation assays that detect circulating unmethylated insulin DNA, and review recent technological advances that have the capacity to improve T1D biomarker development.

Minireview: Emerging Roles for Extracellular Vesicles in Diabetes and Related Metabolic Disorders

Extracellular vesicles (EVs), membrane-contained vesicles released by most cell types, have attracted a large amount of research interest over the past decade. Because of their ability to transfer cargo via regulated processes, causing functional impacts on recipient cells, these structures may play important roles in cell-cell communication and have implications in the physiology of numerous organ systems. In addition, EVs have been described in most human biofluids and have wide potential as relatively noninvasive biomarkers of various pathologic conditions. Specifically, EVs produced by the pancreatic β-cell have been demonstrated to regulate physiologic and pathologic responses to β-cell stress, including β-cell proliferation and apoptosis. β-Cell EVs are also capable of interacting with immune cells and may contribute to the activation of autoimmune processes that trigger or propagate β-cell inflammation and destruction during the development of diabetes. EVs from adipose tissue have been shown to contribute to the development of the chronic inflammation and insulin resistance associated with obesity and metabolic syndrome via interactions with other adipose, liver, and muscle cells. Circulating EVs may also serve as biomarkers for metabolic derangements and complications associated with diabetes. This minireview describes the properties of EVs in general, followed by a more focused review of the literature describing EVs affecting the β-cell, β-cell autoimmunity, and the development of insulin resistance, which all have the potential to affect development of type 1 or type 2 diabetes.

Bruton's Tyrosine Kinase Synergizes with Notch2 To Govern Marginal Zone B Cells in Nonobese Diabetic Mice

Expansion of autoimmune-prone marginal zone (MZ) B cells has been implicated in type 1 diabetes. To test disease contributions of MZ B cells in NOD mice, Notch2 haploinsufficiency (Notch2(+/-)) was introduced but failed to eliminate the MZ, as it does in C57BL/6 mice. Notch2(+/-)/NOD have MZ B cell numbers similar to those of wild-type C57BL/6, yet still develop diabetes. To test whether BCR signaling supports Notch2(+/-)/NOD MZ B cells, Bruton's tyrosine kinase (Btk) deficiency was introduced. Surprisingly, MZ B cells failed to develop in Btk-deficient Notch2(+/-)/NOD mice. Expression of Notch2 and its transcriptional target, Hes5, was increased in NOD MZ B cells compared with C57BL/6 MZ B cells. Btk deficiency reduced Notch2(+/-) signaling exclusively in NOD B cells, suggesting that BCR signaling enhances Notch2 signaling in this autoimmune model. The role of BCR signaling was further investigated using an anti-insulin transgenic (Tg) BCR (125Tg). Anti-insulin B cells in 125Tg/Notch2(+/-)/NOD mice populate an enlarged MZ, suggesting that low-level BCR signaling overcomes reliance on Notch2. Tracking clonotypes of anti-insulin B cells in H chain-only VH125Tg/NOD mice showed that BTK-dependent selection into the MZ depends on strength of antigenic binding, whereas Notch2-mediated selection does not. Importantly, anti-insulin B cell numbers were reduced by Btk deficiency, but not Notch2 haploinsufficiency. These studies show that 1) Notch2 haploinsufficiency limits NOD MZ B cell expansion without preventing type 1 diabetes, 2) BTK supports the Notch2 pathway in NOD MZ B cells, and 3) autoreactive NOD B cell survival relies on BTK more than Notch2, regardless of MZ location, which may have important implications for disease-intervention strategies.

MicroRNA-29b modulates innate and antigen-specific immune responses in mouse models of autoimmunity

In addition to important regulatory roles in gene expression through RNA interference, it has recently been shown that microRNAs display immune stimulatory effects through direct interaction with receptors of innate immunity of the Toll-like receptor family, aggravating neuronal damage and tumour growth. Yet no evidence exists on consequences of microRNA immune stimulatory actions in the context of an autoimmune disease. Using microRNA analogues, we here show that pancreatic beta cell-derived microRNA sequences induce pro-inflammatory (TNFa, IFNa, IL-12, IL-6) or suppressive (IL-10) cytokine secretion by primary mouse dendritic cells in a sequence-dependent manner. For miR-29b, immune stimulation in RAW264.7 macrophages involved the endosomal Toll-like receptor-7, independently of the canonical RNA interference pathway. In vivo, the systemic delivery of miR-29b activates CD11b+B220- myeloid and CD11b-B220+ plasmacytoid dendritic cells and induces IFNa, TNFa and IL-6 production in the serum of recipient mice. Strikingly, in a murine model of adoptive transfer of autoimmune diabetes, miR-29b reduces the cytolytic activity of transferred effector CD8+ T-cells, insulitis and disease incidence in a single standalone intervention. Endogenous miR-29b, spontaneously released from beta-cells within exosomes, stimulates TNFa secretion from spleen cells isolated from diabetes-prone NOD mice in vitro. Hence, microRNA sequences modulate innate and ongoing adaptive immune responses raising the question of their potential role in the breakdown of tolerance and opening up new applications for microRNA-based immune therapy.

Exosomes released by islet-derived mesenchymal stem cells trigger autoimmune responses in NOD mice

Exosomes (EXOs) are secreted, nano-sized membrane vesicles that contain potent immunostimulatory materials. We have recently demonstrated that insulinoma-released EXOs can stimulate the autoimmune responses in nonobese diabetic (NOD) mice, a spontaneous disease model for type 1 diabetes. To investigate whether primary islet cells can produce EXOs, we isolated cells from the islet of Langerhans of NOD mice and cultured them in vitro. Interestingly, cultured islets release fibroblast-like, fast-replicating cells that express mesenchymal stem cell (MSC) markers, including CD105 and stem-cell antigen-1. These islet MSC-like cells release highly immunostimulatory EXOs that could activate autoreactive B and T cells endogenously primed in NOD mice. Serum EXO levels and EXO-induced interferon-γ production were positively correlated with disease progression at the early prediabetic stage. Consistent with these observations, immunohistological analysis of pancreata showed that CD105(+) cells are restricted to the peri-islet area in normal islets but penetrate into the β-cell area as lymphocyte infiltration occurs. Immunization with EXOs promoted expansion of transferred diabetogenic T cells and accelerated the effector T cell-mediated destruction of islets. Thus, EXOs could be the autoantigen carrier with potent adjuvant activities and may function as the autoimmune trigger in NOD mice.

Exosomes in the Pathogenesis, Diagnosis and Treatment of Pancreatic Diseases

Exosomes (EXOs) are small vesicles (30-200 nm) of endocytic origin, which are released by many different cell types into the extracellular space. They may play a key role in facilitating cell-cell communication, under both physiological and pathological conditions. EXOs contain a wide range of RNA molecules and proteins. Their specific molecular signatures make them promising candidates in early diagnosis and prognosis of pancreatic diseases. EXOs could also provide a new method to monitor treatment response in patients suffering from pancreatic cancer and other diseases of the pancreas. Additionally they may help to improve current treatments via personalized medicine approaches using them as therapeutic vehicles themselves.