Testing agents for prevention or reversal of type 1 diabetes in rodents

Islet cells in human type 1 diabetes: from recent advances to novel therapies - a symposium-based roadmap for future research

There is a growing understanding that the early phases of type 1 diabetes (T1D) are characterised by a deleterious dialogue between the pancreatic beta cells and the immune system. This, combined with the urgent need to better translate this growing knowledge into novel therapies, provided the background for the JDRF-DiabetesUK-INNODIA-nPOD symposium entitled 'Islet cells in human T1D: from recent advances to novel therapies', which took place in Stockholm, Sweden, in September 2022. We provide in this article an overview of the main themes addressed in the symposium, pointing to both promising conclusions and key unmet needs that remain to be addressed in order to achieve better approaches to prevent or reverse T1D.

Crosstalk between incretin hormones, Th17 and Treg cells in inflammatory diseases

Intestinal epithelial cells constantly crosstalk with the gut microbiota and immune cells of the gut lamina propria. Enteroendocrine cells, secrete hormones, such as incretin hormones, which participate in host physiological events, such as stimulating insulin secretion, satiety, and glucose homeostasis. Interestingly, evidence suggests that the incretin pathway may influence immune cell activation. Consequently, drugs targeting the incretin hormone signaling pathway may ameliorate inflammatory diseases such as inflammatory bowel diseases, cancer, and autoimmune diseases. In this review, we discuss how these hormones may modulate two subsets of CD4 + T cells, the regulatory T cells (Treg)/Th17 axis important for gut homeostasis: thus, preventing the development and progression of inflammatory diseases. We also summarize the main experimental and clinical findings using drugs targeting the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide (GLP-1) signaling pathways and their great impact on conditions in which the Treg/Th17 axis is disturbed such as inflammatory diseases and cancer. Understanding the role of incretin stimulation in immune cell activation and function, might contribute to new therapeutic designs for the treatment of inflammatory diseases, autoimmunity, and tumors.

Microglial and peripheral immune priming is partially sexually dimorphic in adolescent mouse offspring exposed to maternal high-fat diet

Background

Maternal nutrition is critical for proper fetal development. While increased nutrient intake is essential during pregnancy, an excessive consumption of certain nutrients, like fat, can lead to long-lasting detrimental consequences on the offspring. Animal work investigating the consequences of maternal high-fat diet (mHFD) revealed in the offspring a maternal immune activation (MIA) phenotype associated with increased inflammatory signals. This inflammation was proposed as one of the mechanisms causing neuronal circuit dysfunction, notably in the hippocampus, by altering the brain-resident macrophages—microglia. However, the understanding of mechanisms linking inflammation and microglial activities to pathological brain development remains limited. We hypothesized that mHFD-induced inflammation could prime microglia by altering their specific gene expression signature, population density, and/or functions.

Methods

We used an integrative approach combining molecular (i.e., multiplex-ELISA, rt-qPCR) and cellular (i.e., histochemistry, electron microscopy) techniques to investigate the effects of mHFD (saturated and unsaturated fats) vs control diet on inflammatory priming, as well as microglial transcriptomic signature, density, distribution, morphology, and ultrastructure in mice. These analyses were performed on the mothers and/or their adolescent offspring at postnatal day 30.

Results

Our study revealed that mHFD results in MIA defined by increased circulating levels of interleukin (IL)-6 in the mothers. This phenotype was associated with an exacerbated inflammatory response to peripheral lipopolysaccharide in mHFD-exposed offspring of both sexes. Microglial morphology was also altered, and there were increased microglial interactions with astrocytes in the hippocampus CA1 of mHFD-exposed male offspring, as well as decreased microglia-associated extracellular space pockets in the same region of mHFD-exposed offspring of the two sexes. A decreased mRNA expression of the inflammatory-regulating cytokine Tgfb1 and microglial receptors Tmem119, Trem2, and Cx3cr1 was additionally measured in the hippocampus of mHFD-exposed offspring, especially in males.

Conclusions

Here, we described how dietary habits during pregnancy and nurturing, particularly the consumption of an enriched fat diet, can influence peripheral immune priming in the offspring. We also found that microglia are affected in terms of gene expression signature, morphology, and interactions with the hippocampal parenchyma, in a partially sexually dimorphic manner, which may contribute to the adverse neurodevelopmental outcomes on the offspring.

Oral insulin does not alter gut microbiota composition of NOD mice

BACKGROUND

Oral insulin as a preventive strategy and/or treatment of type 1 diabetes has been the target of much research. Producing oral insulins is a complex and challenging task, with numerous pitfalls, due to physiological, physical, and biochemical barriers. Our aim was to determine the impact of oral insulin on the delicate gut microbiota composition.

METHODS

Female nonobese diabetic mice were given oral porcine insulin 2 times a week from 5 weeks of age for 4 weeks, and then subsequently once a week for 21 weeks, or until euthanized. The mice were divided into groups on a gluten-reduced diet or a standard diet. Gut microbiota composition was analysed based on faecal samples, and the type 1 diabetes incidence of the mice was monitored.

RESULTS

We observed no influence of the oral porcine insulin on the gut microbiota composition of mice on a gluten-reduced or a standard diet at 9 weeks of age. Also, the administration of oral insulin did not influence the incidence of type 1 diabetes at 30 weeks of age.

CONCLUSIONS

Oral porcine insulin does not alter the gut microbiota composition of nonobese diabetic mice on either a gluten-reduced diet or standard diet. Also, the oral porcine insulin did not influence the incidence of type 1 diabetes in the groups.

The Role of NOD Mice in Type 1 Diabetes Research: Lessons from the Past and Recommendations for the Future

For more than 35 years, the NOD mouse has been the primary animal model for studying autoimmune diabetes. During this time, striking similarities to the human disease have been uncovered. In both species, unusual polymorphisms in a major histocompatibility complex (MHC) class II molecule confer the most disease risk, disease is caused by perturbations by the same genes or different genes in the same biological pathways and that diabetes onset is preceded by the presence of circulating autoreactive T cells and autoantibodies that recognize many of the same islet antigens. However, the relevance of the NOD model is frequently challenged due to past failures translating therapies from NOD mice to humans and because the appearance of insulitis in mice and some patients is different. Nevertheless, the NOD mouse remains a pillar of autoimmune diabetes research for its usefulness as a preclinical model and because it provides access to invasive procedures as well as tissues that are rarely procured from patients or controls. The current article is focused on approaches to improve the NOD mouse by addressing reasons why immune therapies have failed to translate from mice to humans. We also propose new strategies for mixing and editing the NOD genome to improve the model in ways that will better advance our understanding of human diabetes. As proof of concept, we report that diabetes is completely suppressed in a knock-in NOD strain with a serine to aspartic acid substitution at position 57 in the MHC class II Aβ. This supports that similar non-aspartic acid substitutions at residue 57 of variants of the human class II HLA-DQβ homolog confer diabetes risk.

Targeting Innate Immunity for Type 1 Diabetes Prevention

PURPOSE OF REVIEW

Despite immense research efforts, type 1 diabetes (T1D) remains an autoimmune disease without a known trigger or approved intervention. Over the last three decades, studies have primarily focused on delineating the role of the adaptive immune system in the mechanism of T1D. The discovery of Toll-like receptors in the 1990s has advanced the knowledge on the role of the innate immune system in host defense as well as mechanisms that regulate adaptive immunity including the function of autoreactive T cells.

RECENT FINDINGS

Recent investigations suggest that inflammation plays a key role in promoting a large number of autoimmune disorders including T1D. Data from the LEW1.WR1 rat model of virus-induced disease and the RIP-B7.1 mouse model of diabetes suggest that innate immune signaling plays a key role in triggering disease progression. There is also evidence that innate immunity may be involved in the course of T1D in humans; however, a small number of clinical trials have shown that interfering with the function of the innate immune system following disease onset exerts only a modest effect on β-cell function. The data implying that innate immune pathways are linked with mechanisms of islet autoimmunity hold great promise for the identification of novel disease pathways that may be harnessed for clinical intervention. Nevertheless, more work needs to be done to better understand mechanisms by which innate immunity triggers β-cell destruction and assess the therapeutic value in blocking innate immunity for diabetes prevention.

Celastrol: A Spectrum of Treatment Opportunities in Chronic Diseases

The identification of new bioactive compounds derived from medicinal plants with significant therapeutic properties has attracted considerable interest in recent years. Such is the case of the Tripterygium wilfordii (TW), an herb used in Chinese medicine. Clinical trials performed so far using its root extracts have shown impressive therapeutic properties but also revealed substantial gastrointestinal side effects. The most promising bioactive compound obtained from TW is celastrol. During the last decade, an increasing number of studies were published highlighting the medicinal usefulness of celastrol in diverse clinical areas. Here we systematically review the mechanism of action and the therapeutic properties of celastrol in inflammatory diseases, namely, rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel diseases, osteoarthritis and allergy, as well as in cancer, neurodegenerative disorders and other diseases, such as diabetes, obesity, atherosclerosis, and hearing loss. We will also focus in the toxicological profile and limitations of celastrol formulation, namely, solubility, bioavailability, and dosage issues that still limit its further clinical application and usefulness.

Tregitopes and impaired antigen presentation: Drivers of the immunomodulatory effects of IVIg?

Introduction

Although intravenous immunoglobulin (IVIg) is commonly used in the clinic to treat various autoimmune and severe inflammatory diseases, the mode of action is not fully elucidated. This work investigates two proposed mechanisms: (1) the potential role of regulatory T‐cell epitopes (Tregitopes) from the constant domain of IgG in the immunosuppressive function of IVIg; and (2) a potential impact of IVIg on the ability of antigen presenting cells (APCs) to present peptides.

Methods and Results

Investigation of the HLA class II peptide repertoire from IVIg‐loaded dendritic cells (DCs) via MHC‐associated peptide proteomics (MAPPs) revealed that numerous IgG‐derived peptides were strongly presented along the antibody sequence. Surprisingly, Tregitopes 167 and 289 did not show efficient natural presentation although they both bound to HLA class II when directly loaded as “naked” peptides on human DCs. In addition, both Tregitopes could not reproduce the inhibitory effect of IVIg in a human in vitro T‐cell proliferation assay as well as in vivo in mice. MAPPs data demonstrate that presentation of peptides from several antigens remained unchanged even when competed with high doses of IVIg, in both human and mouse.

Conclusion

These data suggest that the effects mediated by IVIg are not caused by Tregitopes nor by impaired antigen presentation.

Control of autoimmune inflammation by celastrol, a natural triterpenoid

Celastrol is a bioactive compound derived from traditional Chinese medicinal herbs of the Celastraceae family. Celastrol is known to possess anti-inflammatory and anti-oxidant activities. Our studies have highlighted the immunomodulatory attributes of celastrol in adjuvant-induced arthritis (AA), an experimental model of human rheumatoid arthritis (RA). RA is an autoimmune disease characterized by chronic inflammation of the synovial lining of the joints, leading eventually to tissue damage and deformities. Identification of the molecular targets of celastrol such as the NF-κB pathway, MAPK pathway, JAK/STAT pathway and RANKL/OPG pathway has unraveled its strategic checkpoints in controlling arthritic inflammation and tissue damage in AA. The pathological events that are targeted and rectified by celastrol include increased production of pro-inflammatory cytokines; an imbalance between pathogenic T helper 17 and regulatory T cells; enhanced production of chemokines coupled with increased migration of immune cells into the joints; and increased release of mediators of osteoclastic bone damage. Accordingly, celastrol is a promising candidate for further testing in the clinic for RA therapy. Furthermore, the results of other preclinical studies suggest that celastrol might also be beneficial for the treatment of a few other autoimmune diseases besides arthritis.

A Preclinical Consortium Approach for Assessing the Efficacy of Combined Anti-CD3 Plus IL-1 Blockade in Reversing New-Onset Autoimmune Diabetes in NOD Mice

There is an ongoing need to develop strategic combinations of therapeutic agents to prevent type 1 diabetes (T1D) or to preserve islet β-cell mass in new-onset disease. Although clinical trials using candidate therapeutics are commonly based on preclinical studies, concern is growing regarding the reproducibility as well as the potential clinical translation of reported results using animal models of human disorders. In response, the National Institutes of Health Immune Tolerance Network and JDRF established a multicenter consortium of academic institutions designed to assess the efficacy and intergroup reproducibility of clinically applicable immunotherapies for reversing new-onset disease in the NOD mouse model of T1D. Predicated on prior studies, this consortium conducted coordinated, prospective studies, using joint standard operating procedures, fixed criteria for study entry, and common reagents, to optimize combined anti-CD3 treatment plus interleukin-1 (IL-1) blockade to reverse new-onset disease in NOD mice. We did not find that IL-1 blockade with anti-IL-1β monoclonal antibody or IL-1trap provided additional benefit for reversing new-onset disease compared with anti-CD3 treatment alone. These results demonstrate the value of larger, multicenter preclinical studies for vetting and prioritizing therapeutics for future clinical use.

Celastrol ameliorates cytokine toxicity and pro-inflammatory immune responses by suppressing NF-κB activation in RINm5F beta cells

Upregulation of pro-inflammatory mediators contributes to β-cell destruction and enhanced infiltration of immune cells into pancreatic islets during development of type 1 diabetes mellitus. In this study, we examined the regulatory effects and the mechanisms of action of celastrol against cytotoxicity and pro-inflammatory immune responses in the RINm5F rat pancreatic β-cell line stimulated with a combination of interleukin-1 beta, tumor necrosis factor-alpha, and interferon-γ. Celastrol significantly restored cytokine-induced cell death and significantly inhibited cytokine-induced nitric oxide production. In addition, the protective effect of celastrol was correlated with a reduction in pro-inflammatory mediators, such as inducible nitric oxide synthase, cyclooxygenase-2, and CC chemokine ligand 2. Furthermore, celastrol significantly suppressed cytokine-induced signaling cascades leading to nuclear factor kappa B (NF-κB) activation, including IκB-kinase (IKK) activation, IκB degradation, p65 phosphorylation, and p65 DNA binding activity. These results suggest that celastrol may exert its cytoprotective activity by suppressing cytokine-induced expression of pro-inflammatory mediators by inhibiting activation of NF-κB in RINm5F cells. [BMB Reports 2015; 48(3): 172-177]

Development of EBV-encoded small RNA targeted PCR to classify EBV positive diffuse large B-cell lymphoma (DLBCL) of the elderly

Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) of the elderly has been included in the 2008 WHO classification of lymphoma as a new provisional entity. EBV-positive DLBCL of the elderly is newly classified due to the main occurrence usually in patients of older than 50-year-old. This study was performed in 91 DLBCL patients from January 2002 to December 2012 in Catholic university of St. Vincent Hospital. Age distribution of the patients was 14~87-year-old. Specimens were collected from lymph nodes (n = 45) and extra-lymph nodes (n = 46). EBV encoded small RNA1 in situ hybridization (EBER1-ISH) known as a standard method for the diagnosis of DLBCL. In this study, nested PCR of DNA polymerase gene and EBER PCR were conducted to detect EBV. Presence of EBV was indicated in 3 samples (3.30%) by EBER-ISH, 26 samples (28.57%) by nPCR, and 3 samples (3.30%) by EBER PCR. The concordant results were obtained from EBER1-ISH and EBER PCR. Two samples were classified as EBV-positive DLBCL of the elderly among 91 DLBCL patients. Previously, the incidence rate of DLBCL of the elderly in Asia has been reported as 5~11%, but the result in this study showed a slightly lower incidence rate. To our knowledge, this is the first report on EBV-positive DLBCL of the elderly in Suwon area, Korea. EBER1-ISH and EBER PCR developed in this study may be helpful in classification of EBV-positive DLBCL of the elderly in future.

Celastrol, an oral heat shock activator, ameliorates multiple animal disease models of cell death

Protein homeostatic regulators have been shown to ameliorate single, loss-of-function protein diseases but not to treat broader animal disease models that may involve cell death. Diseases often trigger protein homeostatic instability that disrupts the delicate balance of normal cellular viability. Furthermore, protein homeostatic regulators have been delivered invasively and not with simple oral administration. Here, we report the potent homeostatic abilities of celastrol to promote cell survival, decrease inflammation, and maintain cellular homeostasis in three different disease models of apoptosis and inflammation involving hepatocytes and cardiomyocytes. We show that celastrol significantly recovers the left ventricular function and myocardial remodeling following models of acute myocardial infarction and doxorubicin-induced cardiomyopathy by diminishing infarct size, apoptosis, and inflammation. Celastrol prevents acute liver dysfunction and promotes hepatocyte survival after toxic doses of thioacetamide. Finally, we show that heat shock response (HSR) is necessary and sufficient for the recovery abilities of celastrol. Our observations may have dramatic clinical implications to ameliorate entire disease processes even after cellular injury initiation by using an orally delivered HSR activator.

The dual role of scavenger receptor class A in development of diabetes in autoimmune NOD mice

Human type 1 diabetes is an autoimmune disease that results from the autoreactive destruction of pancreatic β cells by T cells. Antigen presenting cells including dendritic cells and macrophages are required to activate and suppress antigen-specific T cells. It has been suggested that antigen uptake from live cells by dendritic cells via scavenger receptor class A (SR-A) may be important. However, the role of SR-A in autoimmune disease is unknown. In this study, SR-A-/- nonobese diabetic (NOD) mice showed significant attenuation of insulitis, lower levels of insulin autoantibodies, and suppression of diabetes development compared with NOD mice. We also found that diabetes progression in SR-A-/- NOD mice treated with low-dose polyinosinic-polycytidylic acid (poly(I:C)) was significantly accelerated compared with that in disease-resistant NOD mice treated with low-dose poly(I:C). In addition, injection of high-dose poly(I: C) to mimic an acute RNA virus infection significantly accelerated diabetes development in young SR-A-/- NOD mice compared with untreated SR-A-/- NOD mice. Pathogenic cells including CD4+CD25+ activated T cells were increased more in SR-A-/- NOD mice treated with poly(I:C) than in untreated SR-A-/- NOD mice. These results suggested that viral infection might accelerate diabetes development even in diabetes-resistant subjects. In conclusion, our studies demonstrated that diabetes progression was suppressed in SR-A-/- NOD mice and that acceleration of diabetes development could be induced in young mice by poly(I:C) treatment even in SR-A-/- NOD mice. These results suggest that SR-A on antigen presenting cells such as dendritic cells may play an unfavorable role in the steady state and a protective role in a mild infection. Our findings imply that SR-A may be an important target for improving therapeutic strategies for type 1 diabetes.

α1-Antitrypsin therapy downregulates toll-like receptor-induced IL-1β responses in monocytes and myeloid dendritic cells and may improve islet function in recently diagnosed patients with type 1 diabetes

CONTEXT

Recent studies have implicated proinflammatory responses in the mechanism of type 1 diabetes (T1D).

OBJECTIVE

Our objective was to evaluate the safety and effects of therapy with the anti-inflammatory serum protein α1-antitrypsin (AAT) on islet function and innate immunity in recent-onset patients.

DESIGN AND SETTING

This was an open-label phase I trial at the Barbara Davis Center for Childhood Diabetes, University of Colorado Denver.

PATIENTS

Twelve recently diagnosed subjects with T1D with detectable C-peptides were included in the study.

INTERVENTION

Eight consecutive weekly infusions of 80 mg/kg of AAT were given.

MAIN OUTCOME MEASURES

PATIENTS were monitored for adverse effects of AAT therapy, C-peptide responses to a mixed-meal tolerance test, and toll-like receptor (TLR)-induced cellular IL-1β in monocytes and myeloid dendritic cells (mDCs).

RESULTS

No adverse effects were detected. AAT led to increased, unchanged, or moderately reduced levels of C-peptide responses compared with baseline in 5 patients. The total content of TLR4-induced cellular IL-1β in monocytes at 12 months after AAT therapy was 3-fold reduced compared with baseline (P < .05). Furthermore, at baseline, 82% of monocytes produced IL-1β, but at 12 months after therapy, the level decreased to 42%. Similar reductions were observed using TLR7/8 and TLR3 agonists in monocytes and mDCs. Unexpectedly, the reduction in cellular IL-1β was observed only 9 and 12 months after treatment but not in untreated diabetics. Improved β-cell function in the 5 AAT-treated individuals correlated with lower frequencies of monocytes and mDCs producing IL-1β compared with subjects without improvement of islet function (P < .04 and P < .02, respectively).

CONCLUSIONS

We hypothesize that AAT may have a beneficial effect on T1D in recently diagnosed patients that is associated with downmodulation of IL-1β.

Tregitope peptides: the active pharmaceutical ingredient of IVIG?

Five years ago, we reported the identification and characterization of several regulatory T-cell epitopes (now called Tregitopes) that were discovered in the heavy and light chains of IgG (De Groot et al. Blood, 2008). When added ex vivo to human PBMCs, these Tregitopes activated regulatory T cells (Tregs), increased expression of the transcription factor FoxP3, and induced IL-10 expression in CD4(+) T cells. We have now shown that coadministration of the Tregitopes in vivo, in a number of different murine models of autoimmune disease, can suppress immune responses to antigen in an antigen-specific manner, and that this response is mediated by Tregs. In addition we have shown that, although these are generally promiscuous epitopes, the activity of individual Tregitope peptides is restricted by HLA. In this brief report, we provide an overview of the effects of Tregitopes in vivo, discuss potential applications, and suggest that Tregitopes may represent one of the "active pharmaceutical ingredients" of IVIg. Tregitope applications may include any of the autoimmune diseases that are currently treated almost exclusively with intravenous immunoglobulin G (IVIG), such as Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) and Multifocal Motor Neuropathy (MMN), as well as gene therapy and allergy where Tregitopes may provide a means of inducing antigen-specific tolerance.