Mouse models for the study of autoimmune type 1 diabetes: a NOD to similarities and differences to human disease

Advancing Animal Models of Human Type 1 Diabetes

Multiple rodent models have been developed to study the basis of type 1 diabetes (T1D). However, nonobese diabetic (NOD) mice and derivative strains still provide the gold standard for dissecting the basis of the autoimmune responses underlying T1D. Here, we review the developmental origins of NOD mice, and how they and derivative strains have been used over the past several decades to dissect the genetic and immunopathogenic basis of T1D. Also discussed are ways in which the immunopathogenic basis of T1D in NOD mice and humans are similar or differ. Additionally reviewed are efforts to "humanize" NOD mice and derivative strains to provide improved models to study autoimmune responses contributing to T1D in human patients.

Chimeric Antigen Receptor (CAR)-Based Cell Therapy for Type 1 Diabetes Mellitus (T1DM); Current Progress and Future Approaches

Type 1 diabetes mellitus (T1DM) is an autoimmune disease that destroys insulin-producing pancreatic β-cells. Insulin replacement therapy is currently the mainstay of treatment for T1DM; however, treatment with insulin does not ameliorate disease progression, as dysregulated immune response and inflammation continue to cause further pancreatic β-cell degradation. Therefore, shifting therapeutic strategies toward immunomodulating approaches could be effective to prevent and reverse disease progression. Different immune-modulatory therapies could be used, e.g., monoclonal-based immunotherapy, mesenchymal stem cell, and immune cell therapy. Since immune-modulatory approaches could have a systemic effect on the immune system and cause toxicity, more specific treatment options should target the immune response against pancreatic β-cells. In this regard, chimeric antigen receptor (CAR)-based immunotherapy could be a promising candidate for modulation of dysregulated immune function in T1DM. CAR-based therapy has previously been approved for a number of hematologic malignancies. Nevertheless, there is renewed interest in CAR T cells' " off-the-shelf " treatment for T1DM. Several pre-clinical studies demonstrated that redirecting antigen-specific CAR T cells, especially regulatory CAR T cells (CAR Tregs), toward the pancreatic β-cells, could prevent diabetes onset and progression in diabetic mice models. Here, we aim to review the current progress of CAR-based immune-cell therapy for T1DM and the corresponding challenges, with a special focus on designing CAR-based immunomodulatory strategies to improve its efficacy in the treatment of T1DM.

Tipping the balance in autoimmunity: are regulatory t cells the cause, the cure, or both?

Regulatory T cells (Tregs) are a specialized subgroup of T-cell lymphocytes that is crucial for maintaining immune homeostasis and preventing excessive immune responses. Depending on their differentiation route, Tregs can be subdivided into thymically derived Tregs (tTregs) and peripherally induced Tregs (pTregs), which originate from conventional T cells after extrathymic differentiation at peripheral sites. Although the regulatory attributes of tTregs and pTregs partially overlap, their modes of action, protein expression profiles, and functional stability exhibit specific characteristics unique to each subset. Over the last few years, our knowledge of Treg differentiation, maturation, plasticity, and correlations between their phenotypes and functions has increased. Genetic and functional studies in patients with numeric and functional Treg deficiencies have contributed to our mechanistic understanding of immune dysregulation and autoimmune pathologies. This review provides an overview of our current knowledge of Treg biology, discusses monogenetic Treg pathologies and explores the role of Tregs in various other autoimmune disorders. Additionally, we discuss novel approaches that explore Tregs as targets or agents of innovative treatment options.

Selective ablation of thymic and peripheral Foxp3+ regulatory T cell development

Foxp3+ regulatory T (Treg) cells of thymic (tTreg) and peripheral (pTreg) developmental origin are thought to synergistically act to ensure immune homeostasis, with self-reactive tTreg cells primarily constraining autoimmune responses. Here we exploited a Foxp3-dependent reporter with thymus-specific GFP/Cre activity to selectively ablate either tTreg (ΔtTreg) or pTreg (ΔpTreg) cell development, while sparing the respective sister populations. We found that, in contrast to the tTreg cell behavior in ΔpTreg mice, pTreg cells acquired a highly activated suppressor phenotype and replenished the Treg cell pool of ΔtTreg mice on a non-autoimmune C57BL/6 background. Despite the absence of tTreg cells, pTreg cells prevented early mortality and fatal autoimmunity commonly observed in Foxp3-deficient models of complete Treg cell deficiency, and largely maintained immune tolerance even as the ΔtTreg mice aged. However, only two generations of backcrossing to the autoimmune-prone non-obese diabetic (NOD) background were sufficient to cause severe disease lethality associated with different, partially overlapping patterns of organ-specific autoimmunity. This included a particularly severe form of autoimmune diabetes characterized by an early onset and abrogation of the sex bias usually observed in the NOD mouse model of human type 1 diabetes. Genetic association studies further allowed us to define a small set of autoimmune risk loci sufficient to promote β cell autoimmunity, including genes known to impinge on Treg cell biology. Overall, these studies show an unexpectedly high functional adaptability of pTreg cells, emphasizing their important role as mediators of bystander effects to ensure self-tolerance.

Update on the ZNT8 epitope and its role in the pathogenesis of type 1 diabetes

Type 1 diabetes (T1D) is an organ-specific chronic autoimmune disease mediated by autoreactive T cells. ZnT8 is a pancreatic islet-specific zinc transporter that is mainly located in β cells. It not only participates in the synthesis, storage and secretion of insulin but also maintains the structural integrity of insulin. ZnT8 is the main autoantigen recognized by autoreactive CD8+ T cells in children and adults with T1D. This article summarizes the latest research results on the T lymphocyte epitope and B lymphocyte epitope of ZnT8 in the current literature. The structure and expression of ZnT8, the role of ZnT8 in insulin synthesis and its role in autoimmunity are reviewed. ZnT8 is the primary autoantigen of T1D and is specifically expressed in pancreatic islets. Thus, it is one of biomarkers for the diagnosis of T1D. It has broad prospects for further research on immunomodulators for the treatment of T1D.

Antidiabetic and Immunoregulatory Activities of Extract of Phyllanthus emblica L. in NOD with Spontaneous and Cyclophosphamide-Accelerated Diabetic Mice

Oil-Gan, also known as emblica, is the fruit of the genus Phyllanthus emblica L. The fruits are high in nutrients and display excellent health care functions and development values. The primary aim of this study was to investigate the activities of ethyl acetate extract from Phyllanthus emblica L. (EPE) on type 1 diabetes mellitus (T1D) and immunoregulatory activities in non-obese diabetes (NOD) mice with spontaneous and cyclophosphamide (Cyp)-accelerated diabetes. EPE was vehicle-administered to spontaneous NOD (S-NOD) mice or Cyp-accelerated NOD (Cyp-NOD) mice once daily at a dose of 400 mg/kg body weight for 15 or 4 weeks, respectively. At the end, blood samples were collected for biological analyses, organ tissues were dissected for analyses of histology and immunofluorescence (IF) staining (including expressions of Bcl and Bax), the expression levels of targeted genes by Western blotting and forkhead box P3 (Foxp3), and helper T lymphocyte 1 (Th1)/Th2/Th17/Treg regulatory T cell (Treg) cell distribution by flow cytometry. Our results showed that EPE-treated NOD mice or Cyp-accelerated NOD mice display a decrease in levels of blood glucose and HbA1c, but an increase in blood insulin levels. EPE treatment decreased blood levels of IFN-γ and tumor necrosis α (TNF-α) by Th1 cells, and reduced interleukin (IL)-1β and IL-6 by Th17 cells, but increased IL-4, IL-10, and transforming growth factor-β1 (TGF-β1) by Th2 cells in both of the two mice models by enzyme-linked immunosorbent assay (ELISA) analysis. Flow cytometric data showed that EPE-treated Cyp-NOD mice had decreased the CD4⁺ subsets T cell distribution of CD4⁺IL-17 and CD4⁺ interferon gamma (IFN-γ), but increased the CD4⁺ subsets T cell distribution of CD4⁺IL-4 and CD4⁺Foxp3. Furthermore, EPE-treated Cyp-NOD mice had decreased the percentage per 10,000 cells of CD4⁺IL-17 and CD4⁺IFNγ, and increased CD4⁺IL-4 and CD4⁺Foxp3 compared with the Cyp-NOD Con group (p < 0.001, p < 0.05, p < 0.05, and p < 0.05, respectively). For target gene expression levels in the pancreas, EPE-treated mice had reduced expression levels of inflammatory cytokines, including IFN-γ and TNF-α by Th1 cells, but increased expression levels of IL-4, IL-10, and TGF-1β by Th2 cells in both two mice models. Histological examination of the pancreas revealed that EPE-treated mice had not only increased pancreatic insulin-expressing β cells (brown), and but also enhanced the percentage of Bcl-2 (green)/Bax (red) by IF staining analyses of islets compared with the S-NOD Con and the Cyp-NOD Con mice, implying that EPE displayed the protective effects of pancreas β cells. EPE-treated mice showed an increase in the average immunoreactive system (IRS) score on insulin within the pancreas, and an enhancement in the numbers of the pancreatic islets. EPE displayed an improvement in the pancreas IRS scores and a decrease in proinflammatory cytokines. Moreover, EPE exerted blood-glucose-lowering effects by regulating IL-17 expressions. Collectively, these results implied that EPE inhibits the development of autoimmune diabetes by regulating cytokine expression. Our results demonstrated that EPE has a therapeutic potential in the preventive effects of T1D and immunoregulation as a supplementary.

Liraglutide protects β-cells in novel human islet spheroid models of type 1 diabetes

To enable accurate, high-throughput and longer-term studies of the immunopathogenesis of type 1 diabetes (T1D), we established three in-vitro islet-immune injury models by culturing spheroids derived from primary human islets with proinflammatory cytokines, activated peripheral blood mononuclear cells or HLA-A2-restricted preproinsulin-specific cytotoxic T lymphocytes. In all models, β-cell function declined as manifested by increased basal and decreased glucose-stimulated insulin release (GSIS), and decreased intracellular insulin content. Additional hallmarks of T1D progression such as loss of the first-phase insulin response (FFIR), increased proinsulin-to-insulin ratios, HLA-class I expression, and inflammatory cytokine release were also observed. Using these models, we show that liraglutide, a glucagon-like peptide 1 receptor agonist, prevented loss of GSIS under T1D-relevant stress, by preserving the FFIR and decreasing immune cell infiltration and cytokine secretion. Our results corroborate that liraglutide mediates an anti-inflammatory effect that aids in protecting β-cells from the immune-mediated attack that leads to T1D.

Polygenic autoimmune disease risk alleles impacting B cell tolerance act in concert across shared molecular networks in mouse and in humans

Most B cells produced in the bone marrow have some level of autoreactivity. Despite efforts of central tolerance to eliminate these cells, many escape to periphery, where in healthy individuals, they are rendered functionally non-responsive to restimulation through their antigen receptor via a process termed anergy. Broad repertoire autoreactivity may reflect the chances of generating autoreactivity by stochastic use of germline immunoglobulin gene segments or active mechanisms may select autoreactive cells during egress to the naïve peripheral B cell pool. Likewise, it is unclear why in some individuals autoreactive B cell clones become activated and drive pathophysiologic changes in autoimmune diseases. Both of these remain central questions in the study of the immune system(s). In most individuals, autoimmune diseases arise from complex interplay of genetic risk factors and environmental influences. Advances in genome sequencing and increased statistical power from large autoimmune disease cohorts has led to identification of more than 200 autoimmune disease risk loci. It has been observed that autoantibodies are detectable in the serum years to decades prior to the diagnosis of autoimmune disease. Thus, current models hold that genetic defects in the pathways that control autoreactive B cell tolerance set genetic liability thresholds across multiple autoimmune diseases. Despite the fact these seminal concepts were developed in animal (especially murine) models of autoimmune disease, some perceive a disconnect between human risk alleles and those identified in murine models of autoimmune disease. Here, we synthesize the current state of the art in our understanding of human risk alleles in two prototypical autoimmune diseases - systemic lupus erythematosus (SLE) and type 1 diabetes (T1D) along with spontaneous murine disease models. We compare these risk networks to those reported in murine models of these diseases, focusing on pathways relevant to anergy and central tolerance. We highlight some differences between murine and human environmental and genetic factors that may impact autoimmune disease development and expression and may, in turn, explain some of this discrepancy. Finally, we show that there is substantial overlap between the molecular networks that define these disease states across species. Our synthesis and analysis of the current state of the field are consistent with the idea that the same molecular networks are perturbed in murine and human autoimmune disease. Based on these analyses, we anticipate that murine autoimmune disease models will continue to yield novel insights into how best to diagnose, prognose, prevent and treat human autoimmune diseases.

The long and winding road: From mouse linkage studies to a novel human therapeutic pathway in type 1 diabetes

Autoimmunity involves a loss of immune tolerance to self-proteins due to a combination of genetic susceptibility and environmental provocation, which generates autoreactive T and B cells. Genetic susceptibility affects lymphocyte autoreactivity at the level of central tolerance (e.g., defective, or incomplete MHC-mediated negative selection of self-reactive T cells) and peripheral tolerance (e.g., failure of mechanisms to control circulating self-reactive T cells). T regulatory cell (Treg) mediated suppression is essential for controlling peripheral autoreactive T cells. Understanding the genetic control of Treg development and function and Treg interaction with T effector and other immune cells is thus a key goal of autoimmunity research. Herein, we will review immunogenetic control of tolerance in one of the classic models of autoimmunity, the non-obese diabetic (NOD) mouse model of autoimmune Type 1 diabetes (T1D). We review the long (and still evolving) elucidation of how one susceptibility gene, Cd137, (identified originally via linkage studies) affects both the immune response and its regulation in a highly complex fashion. The CD137 (present in both membrane and soluble forms) and the CD137 ligand (CD137L) both signal into a variety of immune cells (bi-directional signaling). The overall outcome of these multitudinous effects (either tolerance or autoimmunity) depends upon the balance between the regulatory signals (predominantly mediated by soluble CD137 via the CD137L pathway) and the effector signals (mediated by both membrane-bound CD137 and CD137L). This immune balance/homeostasis can be decisively affected by genetic (susceptibility vs. resistant alleles) and environmental factors (stimulation of soluble CD137 production). The discovery of the homeostatic immune effect of soluble CD137 on the CD137-CD137L system makes it a promising candidate for immunotherapy to restore tolerance in autoimmune diseases.

Mouse Homologue of Human HLA-DO Does Not Preempt Autoimmunity but Controls Murine Gammaherpesvirus MHV68

H2-O (human HLA-DO) is a relatively conserved nonclassical MHC class II (MHCII)-like molecule. H2-O interaction with human HLA-DM edits the repertoire of peptides presented to TCRs by MHCII. It was long hypothesized that human HLA-DM inhibition by H2-O provides protection from autoimmunity by preventing binding of the high-affinity self-peptides to MHCII. The available evidence supporting this hypothesis, however, was inconclusive. A possibility still remained that the effect of H2-O deficiency on autoimmunity could be better revealed by using H2-O-deficient mice that were already genetically predisposed to autoimmunity. In this study, we generated and used autoimmunity-prone mouse models for systemic lupus erythematosus and organ-specific autoimmunity (type 1 diabetes and multiple sclerosis) to definitively test whether H2-O prevents autoimmune pathology. Whereas our data failed to support any significance of H2-O in protection from autoimmunity, we found that it was critical for controlling a γ-herpesvirus, MHV68. Thus, we propose that H2-O editing of the MHCII peptide repertoire may have evolved as a safeguard against specific highly prevalent viral pathogens.

Interleukin-35: Structure, Function and Its Impact on Immune-Related Diseases

The balance between inflammatory and anti-inflammatory immune responses is maintained through immunoregulatory cell populations and immunosuppressive cytokines. Interleukin-35 (IL-35), an inhibitory cytokine that belongs to the IL-12 family, is capable of potently suppressing T cell proliferation and inducing IL-35-producing induced regulatory T cells (iTr35) to limit inflammatory responses. Over the past decade, a growing number of studies have indicated that IL-35 plays an important role in controlling immune-related disorders, including autoimmune diseases, infectious diseases, and cancer. In this review, we summarize the current knowledge about the biology of IL-35 and its contribution in different diseases, and we discuss the potential of and barriers to harnessing IL-35 as a clinical biomarker or immunotherapy.

Genome Editing Human Pluripotent Stem Cells to Model β-Cell Disease and Unmask Novel Genetic Modifiers

A mechanistic understanding of the genetic basis of complex diseases such as diabetes mellitus remain elusive due in large part to the activity of genetic disease modifiers that impact the penetrance and/or presentation of disease phenotypes. In the face of such complexity, rare forms of diabetes that result from single-gene mutations (monogenic diabetes) can be used to model the contribution of individual genetic factors to pancreatic β-cell dysfunction and the breakdown of glucose homeostasis. Here we review the contribution of protein coding and non-protein coding genetic disease modifiers to the pathogenesis of diabetes subtypes, as well as how recent technological advances in the generation, differentiation, and genome editing of human pluripotent stem cells (hPSC) enable the development of cell-based disease models. Finally, we describe a disease modifier discovery platform that utilizes these technologies to identify novel genetic modifiers using induced pluripotent stem cells (iPSC) derived from patients with monogenic diabetes caused by heterozygous mutations.

Skeletal Response to Insulin in the Naturally Occurring Type 1 Diabetes Mellitus Mouse Model

Patients with type 1 diabetes mellitus (T1DM) exhibit reduced BMD and significant increases in fracture risk. Changes in BMD are attributed to blunted osteoblast activity and inhibited bone remodeling, but these cannot fully explain the impaired bone integrity in T1DM. The goal of this study was to determine the cellular mechanisms that contribute to impaired bone morphology and composition in T1DM. Nonobese diabetic (NOD) mice were used, along with μCT, histomorphometry, histology, Raman spectroscopy, and RNAseq analyses of several skeletal sites in response to naturally occurring hyperglycemia and insulin treatment. The bone volume in the axial skeleton was found to be severely reduced in diabetic NOD mice and was not completely resolved with insulin treatment. Decreased bone volume in diabetic mice was associated with increased sclerostin expression in osteocytes and attenuation of bone formation indices without changes in bone resorption. In the face of blunted bone remodeling, decreases in the mineral:matrix ratio were found in cortical bones of diabetic mice by Raman microspectroscopy, suggesting that T1DM did not affect the bone mineralization process per se, but rather resulted in microenvironmental alterations that favored mineral loss. Bone transcriptome analysis indicated metabolic shifts in response to T1DM. Dysregulation of genes involved in fatty acid oxidation, transport, and synthesis was found in diabetic NOD mice. Specifically, pyruvate dehydrogenase kinase isoenzyme 4 and glucose transporter 1 levels were increased, whereas phosphorylated-AKT levels were significantly reduced in diabetic NOD mice. In conclusion, in addition to the blunted bone formation, osteoblasts and osteocytes undergo metabolic shifts in response to T1DM that may alter the microenvironment and contribute to mineral loss from the bone matrix. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

NOD Mice Recapitulate the Cardiac Disturbances Observed in Type 1 Diabetes

This work aimed at testing the hypothesis that NOD/ShiLtJ mice (NOD) recapitulate the cardiac disturbances observed on type 1 diabetes (T1D). NOD mice were studied 4 weeks after the onset of hyperglycemia, and NOR/Lt mice matched as control. Cardiac function was evaluated by echocardiography and electrocardiography (ECG). Action potentials (AP) and Ca2+ transients were evaluated at whole heart level. Heart mitochondrial function was evaluated by high-resolution respirometry and H2O2 release. NOD mice presented a reduction in hearth weight. Mitochondrial oxygen fluxes and H2O2 release were similar between NOD and NOR mice. ECG revealed a QJ interval prolongation in NOD mice. Furthermore, AP duration at 30% of repolarization was increased, and it depicted slower Ca2+ transient kinetics. NOD mice presented greater number/severity of ventricular arrhythmias both in vivo and in vitro. In conclusion, NOD mice evoked cardiac electrical and calcium handling disturbances similar to the observed in T1D. Graphical Abstract .

Evidence of genetic epistasis in autoimmune diabetes susceptibility revealed by mouse congenic sublines

Susceptibility to autoimmune diabetes is a complex genetic trait. Linkage analyses exploiting the NOD mouse, which spontaneously develops autoimmune diabetes, have proved to be a useful tool for the characterization of some of these traits. In a linkage analysis using 3A9 TCR transgenic mice on both B10.BR and NOD.H2^k backgrounds, we previously determined that both the Idd2 and Idd13 loci were linked to the proportion of immunoregulatory CD4^-CD8^- double negative (DN) T cells. In addition to Idd2 and Idd13, five other loci showed weak linkage to the proportion of DN T cells. Of interest, in an interim analysis, a locus on chromosome 12 is linked to DN T cell proportion in both the spleen and the lymph nodes. To determine the impact of this locus on DN T cells, we generated two congenic sublines, which we named Chr12P and Chr12D for proximal and distal, respectively. While 3A9 TCR:insHEL NOD.H2^k-Chr12D mice were protected from diabetes, 3A9 TCR:insHEL NOD.H2^k-Chr12P showed an increase in diabetes incidence. Yet, the proportion of DN T cells was similar to the parental 3A9 TCR NOD.H2^k strain for both of these congenic sublines. A genome-wide two dimensional LOD score analysis reveals genetic epistasis between chromosome 12 and the Idd13 locus. Altogether, this study identified further complex genetic interactions in defining the proportion of DN T cells, along with evidence of genetic epistasis within a locus on chromosome 12 influencing autoimmune susceptibility.

Polymorphisms in canine immunoglobulin heavy chain gene cluster: a double-edged sword for diabetes mellitus in the dog

Insulin deficiency diabetes (IDD) in dogs is an endocrine disease similar to human type 1 diabetes. There are breeds more commonly affected, such as Yorkshire Terrier and Samoyed, suggesting an underlying genetic component. However, the genetic basis for canine diabetes mellitus (DM) is not fully established. We conducted both whole-genome scans for selection signatures and GWASs to compare the genomes of 136 dogs belonging to 29 breeds previously described at low or high risk for developing DM. Candidate variants were tested in dogs with a diagnosis of IDD and controls attending the Complutense Veterinary Teaching Hospital. The only genomic region under selection (CFA8:72 700 000-74 600 000; CanFam3.1) retrieved by our analyses is included in the immunoglobulin heavy chain gene cluster, which has already been related to human human type 1 diabetes susceptibility. This region contains two non-synonymous variants, rs852072969 and rs851728071, showing significant associations with high or low risk for IDD, respectively. The first variant, rs852072969, alters a protein poorly characterised in the dog. In contrast, rs851728071 was predicted to block the synthesis of an immunoglobulin variable (V) domain in breeds at low risk for DM. Although a large and diverse V gene repertoire is thought to offer a fitness advantage, we suggest that rs851728071 prevents the formation of an auto-reactive immunoglobulin V domain probably involved in the pathophysiology of IDD and, thus, decreases the risk for the disease. These results should be interpreted with caution until the functional roles of the proposed variants have been proved in larger studies.

Evolving Antibody Therapies for the Treatment of Type 1 Diabetes

Type 1 diabetes (T1D) is widely considered to be a T cell driven autoimmune disease resulting in reduced insulin production due to dysfunction/destruction of pancreatic β cells. Currently, there continues to be a need for immunotherapies that selectively reestablish persistent β cell-specific self-tolerance for the prevention and remission of T1D in the clinic. The utilization of monoclonal antibodies (mAb) is one strategy to target specific immune cell populations inducing autoimmune-driven pathology. Several mAb have proven to be clinically safe and exhibit varying degrees of efficacy in modulating autoimmunity, including T1D. Traditionally, mAb therapies have been used to deplete a targeted cell population regardless of antigenic specificity. However, this treatment strategy can prove detrimental resulting in the loss of acquired protective immunity. Nondepleting mAb have also been applied to modulate the function of immune effector cells. Recent studies have begun to define novel mechanisms associated with mAb-based immunotherapy that alter the function of targeted effector cell pools. These results suggest short course mAb therapies may have persistent effects for regaining and maintaining self-tolerance. Furthermore, the flexibility to manipulate mAb properties permits the development of novel strategies to target multiple antigens and/or deliver therapeutic drugs by a single mAb molecule. Here, we discuss current and potential future therapeutic mAb treatment strategies for T1D, and T cell-mediated autoimmunity.

UBASH3A deficiency accelerates type 1 diabetes development and enhances salivary gland inflammation in NOD mice

Recent advances in genetic analyses have significantly refined human type 1 diabetes (T1D) associated loci. The goal of such effort is to identify the causal genes and have a complete understanding of the molecular pathways that independently or interactively influence cellular processes leading to the destruction of insulin producing pancreatic β cells. UBASH3A has been suggested as the underlying gene for a human T1D associated region on chromosome 21. To further evaluate the role of UBASH3A in T1D, we targeted Ubash3a in NOD mice using zinc-finger nuclease mediated mutagenesis. In both 10-week-old females and males, significantly more advanced insulitis was observed in UBASH3A-deficient than in wild-type NOD mice. Consistently, UBASH3A-deficient NOD mice developed accelerated T1D in both sexes, which was associated with increased accumulation of β-cell autoreactive T cells in the spleen and pancreatic lymph node. Adoptive transfer of splenic T cells into NOD.Rag1^-/- mice demonstrated that UBASH3A deficiency in T cells was sufficient to promote T1D development. Our results provide strong evidence to further support a role of UBASH3A in T1D. In addition to T1D, UBASH3A deficiency also promoted salivary gland inflammation in females, demonstrating its broad impact on autoimmunity.

Injection of CD40 DNA vaccine ameliorates the autoimmune pathology of non-obese diabetic mice with Sjögren's syndrome

BACKGROUND

Overexpression of CD40 has been reported in patients with primary Sjögren's syndrome (pSS). The increased CD40 expression promote autoimmune response and enhance inflammation in pSS. The aim of this study is to block CD40-CD154 interaction with CD40 DNA vaccine to slow the disease progression of SS in non-obese diabetic (NOD) mice.

METHODS

Female NOD mice were treated with CD40 DNA vaccine, empty vector and normal saline. The salivary flow rate was measured, whereas lymphocytes infiltration in the salivary glands was assessed by histopathology. Expression of CD40 and B220 in salivary were examined by immunohistochemistry. Splenic lymphocyte phenotypes were analyzed by flow cytometry. CD40, IL-1β, TNF-α and IL-6 levels in the salivary glands were detected by PCR. Serum anti-CD40 antibody was measured by ELISA. Serum anti-nuclear antibody (ANA) was monitored by immunofluorescence.

RESULTS

NOD mice treated with CD40 DNA vaccine showed higher levels of anti-CD40 antibody compared with the controls. The expression of CD40 in the salivary glands of NOD mice in CD40 DNA vaccine group was decreased. The infiltration of lymphocytes was reduced in the salivary glands and saliva secretion was increased in the treatment group. The expression level of TNF-α and IL-6 in salivary glands were declined. The splenic dendritic cell and plasma cell populations were reduced and the level of ANA was decreased in NOD mice with CD40 DNA vaccine treatment.

CONCLUSIONS

CD40 DNA vaccine inhibits the immune response and reduce inflammation in epithelial tissues SS in non-obese diabetic (NOD) mice, suggesting that CD40 DNA vaccine could be a new therapeutic approach in treatment of pSS.

The CD137 Ligand Is Important for Type 1 Diabetes Development but Dispensable for the Homeostasis of Disease-Suppressive CD137+ FOXP3+ Regulatory CD4 T Cells

CD137 modulates type 1 diabetes (T1D) progression in NOD mice. We previously showed that CD137 expression in CD4 T cells inhibits T1D, but its expression in CD8 T cells promotes disease development by intrinsically enhancing the accumulation of β-cell-autoreactive CD8 T cells. CD137 is expressed on a subset of FOXP3+ regulatory CD4 T cells (Tregs), and CD137+ Tregs are the main source of soluble CD137. Soluble CD137 suppresses T cells in vitro by binding to the CD137 ligand (CD137L) upregulated on activated T cells. To further study how the opposing functions of CD137 are regulated, we successfully targeted Tnfsf9 (encoding CD137L) in NOD mice using the CRISPR/Cas9 system (designated NOD.Tnfsf9 -/-). Relative to wild-type NOD mice, T1D development in the NOD.Tnfsf9 -/- strain was significantly delayed, and mice developed less insulitis and had reduced frequencies of β-cell-autoreactive CD8 T cells. Bone marrow chimera experiments showed that CD137L-deficient hematopoietic cells were able to confer T1D resistance. Adoptive T cell transfer experiments showed that CD137L deficiency on myeloid APCs was associated with T1D suppression. Conversely, lack of CD137L on T cells enhanced their diabetogenic activity. Furthermore, neither CD137 nor CD137L was required for the development and homeostasis of FOXP3+ Tregs. However, CD137 was critical for the in vivo T1D-suppressive activity of FOXP3+ Tregs, suggesting that the interaction between CD137 and CD137L regulates their function. Collectively, our results provide new insights into the complex roles of CD137-CD137L interaction in T1D.

Immune checkpoint inhibitor diabetes mellitus: a novel form of autoimmune diabetes

Autoimmune diabetes mellitus is a rare but significant side effect of treatment with immune checkpoint inhibitors. Immune checkpoint inhibitor-induced diabetes mellitus (CPI-DM) is characterized by acute onset of dramatic hyperglycemia with severe insulin deficiency and occurrence following exposure to programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) inhibitors rather than cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) inhibitors. As a growing number of patients undergo immunotherapy, further understanding of the characteristics of CPI-DM patients is needed for improved prognostic and diagnostic application in order to reduce overall morbidity for this already at-risk population. Additionally, understanding of the features and mechanisms of CPI-DM may contribute to understanding mechanisms of spontaneous type I diabetes mellitus (T1DM). Here, we summarize the clinical features of CPI-DM and interrogate the genetic and cellular mechanisms that may contribute to the disease, as well as the clinical challenges for predicting and treating these patients as increasing cancer immunotherapies reach clinical utility.

Amelioration of type 1 diabetes by recombinant fructose-1,6-bisphosphate aldolase and cystatin derived from Schistosoma japonicum in a murine model

Infection with helminth parasites or the administration of their antigens can prevent or attenuate autoimmune diseases. To date, the specific molecules that prime the amelioration are only limited. In this study, recombinant Schistosoma japonicum cystatin (rSjcystatin) and fructose-1,6-bisphosphate aldolase (rSjFBPA) were administered to female NOD mice via intraperitoneal (i.p.) injection to characterize the immunological response by the recombinant proteins. We have shown that the administration of rSjcystatin or rSjFBPA significantly reduced the diabetes incidence and ameliorated the severity of type 1 diabetes mellitus (T1DM). Disease attenuation was associated with suppressed interferon-gamma (IFN-γ) production in autoreactive T cells and with a switch to the production of Th2 cytokines. Following rSjcystatin or rSjFBPA injection, regulatory T cells (Tregs) were remarkably increased, which was accompanied by increased expression of interleukin-10 (IL-10) and transforming growth factor beta (TGF-β). Our study suggests that helminth-derived proteins may be useful in strategies to limit pathology by promoting the Th2 response and upregulating Tregs during the inflammatory tissue-damage process in T1DM.

Interleukin-27 Is Essential for Type 1 Diabetes Development and Sjögren Syndrome-like Inflammation

Human genetic studies implicate interleukin-27 (IL-27) in the pathogenesis of type 1 diabetes (T1D), but the underlying mechanisms remain largely unexplored. To further define the role of IL-27 in T1D, we generated non-obese diabetic (NOD) mice deficient in IL-27 or IL-27Rα. In contrast to wild-type NOD mice, both NOD.Il27-/- and NOD.Il27ra-/- strains are completely resistant to T1D. IL-27 from myeloid cells and IL-27 signaling in T cells are critical for T1D development. IL-27 directly alters the balance of regulatory T cells (Tregs) and T helper 1 (Th1) cells in pancreatic islets, which in turn modulates the diabetogenic activity of CD8 T cells. IL-27 also directly enhances the effector function of CD8 T cells within pancreatic islets. In addition to T1D, IL-27 signaling in T cells is also required for lacrimal and salivary gland inflammation in NOD mice. Our study reveals that IL-27 contributes to autoimmunity in NOD mice through multiple mechanisms and provides substantial evidence to support its pathogenic role in human T1D.

T-Cell-Specific PTPN2 Deficiency in NOD Mice Accelerates the Development of Type 1 Diabetes and Autoimmune Comorbidities

Genome-wide association studies have identified PTPN2 as an important non-MHC gene for autoimmunity. Single nucleotide polymorphisms that reduce PTPN2 expression have been linked with the development of various autoimmune disorders, including type 1 diabetes. The tyrosine phosphatase PTPN2 attenuates T-cell receptor and cytokine signaling in T cells to maintain peripheral tolerance, but the extent to which PTPN2 deficiency in T cells might influence type 1 diabetes onset remains unclear. NOD mice develop spontaneous autoimmune type 1 diabetes similar to that seen in humans. In this study, T-cell PTPN2 deficiency in NOD mice markedly accelerated the onset and increased the incidence of type 1 diabetes as well as that of other disorders, including colitis and Sjögren syndrome. Although PTPN2 deficiency in CD8⁺ T cells alone was able to drive the destruction of pancreatic β-cells and the onset of diabetes, T-cell-specific PTPN2 deficiency was also accompanied by increased CD4⁺ T-helper type 1 differentiation and T-follicular-helper cell polarization and increased the abundance of B cells in pancreatic islets as seen in human type 1 diabetes. These findings causally link PTPN2 deficiency in T cells with the development of type 1 diabetes and associated autoimmune comorbidities.

Combined congenic mapping and nuclease-based gene targeting for studying allele-specific effects of Tnfrsf9 within the Idd9.3 autoimmune diabetes locus

Rodent complex trait genetic studies involving a cross between two inbred strains are usually followed by congenic mapping to refine the loci responsible for the phenotype. However, progressing from a chromosomal region to the actual causal gene remains challenging because multiple polymorphic genes are often closely linked. The goal of this study was to develop a strategy that allows candidate gene testing by allele-specific expression without prior knowledge of the credible causal variant. Tnfrsf9 (encoding CD137) is a candidate gene for the Idd9.3 type 1 diabetes (T1D) susceptibility locus in the nonobese diabetic (NOD) mouse model. A C57BL/10Sn (B10)-derived diabetes resistance Idd9.3 congenic region has been shown to enhance accumulation of CD137⁺ regulatory T cells and serum soluble CD137 in NOD mice. By combining the power of congenic mapping and nuclease-based gene targeting, we established a system where a pair of F1 hybrids expressed either the B10 or NOD Tnfrsf9 allele mimicking coisogenic strains. Using this approach, we demonstrated that the allelic difference in B10 and NOD Tnfrsf9 alone was sufficient to cause differential accumulation of CD137⁺ regulatory T cells and serum soluble CD137 levels. This strategy can be broadly applied to other rodent genetic mapping studies.

Determining Antigen Specificity of Human Islet Infiltrating T Cells in Type 1 Diabetes

Type 1 diabetes, the immune mediated form of diabetes, represents a prototypical organ specific autoimmune disease in that insulin producing pancreatic islets are specifically targeted by T cells. The disease is now predictable in humans with the measurement of type 1 diabetes associated autoantibodies (islet autoantibodies) in the peripheral blood which are directed against insulin and beta cell proteins. With an increasing incidence of disease, especially in young children, large well-controlled clinical prevention trials using antigen specific immunotherapy have been completed but with limited clinical benefit. To improve outcomes, it is critical to understand the antigen and T cell receptor repertoires of those cells that infiltrate the target organ, pancreatic islets, in human type 1 diabetes. With international networks to identify organ donors with type 1 diabetes, improved immunosequencing platforms, and the ability to reconstitute T cell receptors of interest into immortalized cell lines allows antigen discovery efforts for rare tissue specific T cells. Here we review the disease pathogenesis of type 1 diabetes with a focus on human islet infiltrating T cell antigen discovery efforts, which provides necessary knowledge to define biomarkers of disease activity and improve antigen specific immunotherapy approaches for disease prevention.

Redox-Sensitive Innate Immune Pathways During Macrophage Activation in Type 1 Diabetes

SIGNIFICANCE

Type 1 diabetes (T1D) is an autoimmune disease resulting in β-cell destruction mediated by islet-infiltrating leukocytes. The role of oxidative stress in human and murine models of T1D is highly significant as these noxious molecules contribute to diabetic complications and β-cell lysis, but their direct impact on dysregulated autoimmune responses is highly understudied. Pro-inflammatory macrophages play a vital role in the initiation and effector phases of T1D by producing free radicals and pro-inflammatory cytokines to facilitate β-cell destruction and to present antigen to autoreactive T cells. Recent Advances: Redox modulation of macrophage functions may play critical roles in autoimmunity. These include enhancing pro-inflammatory innate immune signaling pathways in response to environmental triggers, enforcing an M1 macrophage differentiation program, controlling antigen processing, and altering peptide recognition by oxidative post-translational modification. Therefore, an oxidative environment may act on multiple macrophage functions to orchestrate T1D pathogenesis.

CRITICAL ISSUES

Mechanisms involved in the initiation of T1D remain unclear, making preventive and early therapeutics difficult to develop. Although many of these advances in the redox regulation of macrophages are in their infancy, they provide insight into how oxidative stress aids in the precipitating event of autoimmune activation.

FUTURE DIRECTIONS

Future studies should be aimed at mechanistically determining which redox-regulated macrophage functions are pertinent in T1D pathogenesis, as well as at investigating potential targetable therapeutics to halt and/or dampen innate immune activation in T1D.

A Hypermorphic Nfkbid Allele Contributes to Impaired Thymic Deletion of Autoreactive Diabetogenic CD8+ T Cells in NOD Mice

In both NOD mice and humans, the development of type 1 diabetes (T1D) is dependent in part on autoreactive CD8+ T cells recognizing pancreatic β cell peptides presented by often quite common MHC class I variants. Studies in NOD mice previously revealed that the common H2-Kd and/or H2-Db class I molecules expressed by this strain aberrantly lose the ability to mediate the thymic deletion of pathogenic CD8+ T cell responses through interactions with T1D susceptibility genes outside the MHC. A gene(s) mapping to proximal chromosome 7 was previously shown to be an important contributor to the failure of the common class I molecules expressed by NOD mice to mediate the normal thymic negative selection of diabetogenic CD8+ T cells. Using an inducible model of thymic negative selection and mRNA transcript analyses, we initially identified an elevated Nfkbid expression variant as a likely NOD-proximal chromosome 7 region gene contributing to impaired thymic deletion of diabetogenic CD8+ T cells. CRISPR/Cas9-mediated genetic attenuation of Nfkbid expression in NOD mice resulted in improved negative selection of autoreactive diabetogenic AI4 and NY8.3 CD8+ T cells. These results indicated that allelic variants of Nfkbid contribute to the efficiency of intrathymic deletion of diabetogenic CD8+ T cells. However, although enhancing thymic deletion of pathogenic CD8+ T cells, ablating Nfkbid expression surprisingly accelerated T1D onset that was associated with numeric decreases in both regulatory T and B lymphocytes in NOD mice.

The proinflammatory effects of macrophage-derived NADPH oxidase function in autoimmune diabetes

Type 1 diabetes (T1D) is an autoimmune disease culminating in the destruction of insulin-producing pancreatic β-cells. While ultimately a T cell-mediated disease, macrophages play an indispensable role in disease initiation and progression. Infiltrating macrophages generate an inflammatory environment by releasing NADPH oxidase-derived superoxide and proinflammatory cytokines. The synthesis of reactive oxygen species (ROS) is acknowledged as putative factors contributing to autoimmunity and β-cell damage in T1D. In addition to direct lysis, free radicals collectively participate in β-cell destruction by providing a redox-dependent third signal necessary for islet-reactive CD4 and CD8 T cell maturation and by inducing oxidative post-translational modifications of β-cell epitopes to further exacerbate autoimmune responses. This review will provide an overview of macrophage function and a synergistic cross-talk with redox biology that contributes to autoimmune dysregulation in T1D.

Genetic interaction between two insulin-dependent diabetes susceptibility loci, Idd2 and Idd13, in determining immunoregulatory DN T cell proportion

Several immune regulatory cell types participate in the protection against autoimmune diseases such as autoimmune diabetes. Of these immunoregulatory cells, we and others have shown that peripheral CD4^-CD8^- double negative (DN) T cells can induce antigen-specific immune tolerance. Particularly, we have described that diabetes-prone mice exhibit a lower number of peripheral DN T cells compared to diabetes-resistant mice. Identifying the molecular pathways that influence the size of the DN T cell pool in peripheral lymphoid organs may thus be of interest for maintaining antigen-specific immune tolerance. Hence, through immunogenetic approaches, we found that two genetic loci linked to autoimmune diabetes susceptibility, namely Idd2 and Idd13, independently contribute to the partial restoration of DN T cell proportion in secondary lymphoid organs. We now extend these findings to show an interaction between the Idd2 and Idd13 loci in determining the number of DN T cells in secondary lymphoid organs. Using bioinformatics tools, we link potential biological pathways arising from interactions of genes encoded within the two loci. By focusing on cell cycle, we validate that both the Idd2 and Idd13 loci influence RAD51 expression as well as DN T cell progression through the cell cycle. Altogether, we find that genetic interactions between Idd2 and Idd13 loci modulate cell cycle progression, which contributes, at least in part, to defining the proportion of DN T cells in secondary lymphoid organs.

Autoimmune-Disease-Prone NOD Mice Help To Reveal a New Genetic Locus for Reducing Pulmonary Disease Caused by Mycoplasma pulmonis

Mycoplasmas are bacterial pathogens of a range of animals, including humans, and are a common cause of respiratory disease. However, the host genetic factors that affect resistance to infection or regulate the resulting pulmonary inflammation are not well defined. We and others have previously demonstrated that nonobese diabetic (NOD) mice can be used to investigate disease loci that affect bacterial infection and autoimmune diabetes. Here we show that NOD mice are more susceptible than C57BL/6 (B6) mice to infection with Mycoplasma pulmonis, a natural model of pulmonary mycoplasmosis. The lungs of infected NOD mice had higher loads of M. pulmonis and more severe inflammatory lesions. Moreover, congenic NOD mice that harbored different B6-derived chromosomal intervals enabled identification and localization of a new mycoplasmosis locus, termed Mpr2, on chromosome 13. These congenic NOD mice demonstrated that the B6 allele for Mpr2 reduced the severity of pulmonary inflammation caused by infection with M. pulmonis and that this was associated with altered cytokine and chemokine concentrations in the infected lungs. Mpr2 also colocalizes to the same genomic interval as Listr2 and Idd14, genetic loci linked to listeriosis resistance and autoimmune diabetes susceptibility, respectively, suggesting that allelic variation within these loci may affect the development of both infectious and autoimmune disease.

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.

Autoimmune manifestations in aged mice arise from early-life immune dysregulation

Autoantibodies can be present years to decades before the onset of disease manifestations in autoimmunity. This finding suggests that the initial autoimmune trigger involves a peripheral lymphoid component, which ultimately drives disease pathology in local tissues later in life. We show that Sjögren's syndrome manifestations that develop in aged NOD.H-2h4 mice were driven by and dependent on peripheral dysregulation that arose in early life. Specifically, elimination of spontaneous germinal centers in spleens of young NOD.H-2h4 mice by transient blockade of CD40 ligand (CD40L) or splenectomy abolished Sjögren's pathology of aged mice. Strikingly, a single injection of anti-CD40L at 4 weeks of age prevented tertiary follicle neogenesis and greatly blunted the formation of key autoantibodies implicated in glandular pathology, including anti-muscarinic receptor antibodies. Microarray profiling of the salivary gland characterized the expression pattern of genes that increased with disease progression and showed that early anti-CD40L greatly repressed B cell function while having a broader effect on multiple biological pathways, including interleukin-12 and interferon signaling. A single prophylactic treatment with anti-CD40L also inhibited the development of autoimmune thyroiditis and diabetes in NOD.H-2h4 and nonobese diabetic mice, respectively, supporting a key role for CD40L in the pathophysiology of several autoimmune models. These results strongly suggest that early peripheral immune dysregulation gives rise to autoimmune manifestations later in life, and for diseases predated by autoantibodies, early prophylactic intervention with biologics may prove efficacious.

Current practices and future outlook on the integration of biomarkers in the drug development process

Over the last decade, there has been broad incorporation of translational biomarkers into the early drug development process to predict safety concerns, measure target engagement and monitor disease progression. One goal of translational biomarkers is to create a cycle whereby preclinical readouts influence candidate selection and subsequent clinical data are fed back into research to facilitate better decision making. Successes have been limited and not as broad in scope as desired. Collaborations between industry and regulators have increased the number of qualified biomarkers; but the process is lengthy and expensive. A high level overview of translational biomarkers as well as a discussion of some of the successes and failures encountered in development is discussed here.

The Type 1 Diabetes-Resistance Locus Idd22 Controls Trafficking of Autoreactive CTLs into the Pancreatic Islets of NOD Mice

Type 1 diabetes (T1D) has a strong genetic component. The insulin dependent diabetes (Idd)22 locus was identified in crosses of T1D-susceptible NOD mice with the strongly T1D-resistant ALR strain. The NODcALR-(D8Mit293-D8Mit137)/Mx (NOD-Idd22) recombinant congenic mouse strain was generated in which NOD mice carry the full Idd22 confidence interval. NOD-Idd22 mice exhibit almost complete protection from spontaneous T1D and a significant reduction in insulitis. Our goal was to unravel the mode of Idd22-based protection using in vivo and in vitro models. We determined that Idd22 did not impact immune cell diabetogenicity or β cell resistance to cytotoxicity in vitro. However, NOD-Idd22 mice were highly protected against adoptive transfer of T1D. Transferred CTLs trafficked to the pancreatic lymph node and proliferated to the same extent in NOD and NOD-Idd22 mice, yet the accumulation of pathogenic CTLs in the islets was significantly reduced in NOD-Idd22 mice, correlating with disease resistance. Pancreatic endothelial cells from NOD-Idd22 animals expressed lower levels of adhesion molecules, even in response to inflammatory stimuli. Lower adhesion molecule expression resulted in weaker adherence of T cells to NOD-Idd22 endothelium compared with NOD-derived endothelium. Taken together, these results provide evidence that Idd22 regulates the ability of β cell-autoreactive T cells to traffic into the pancreatic islets and may represent a new target for pharmaceutical intervention to potentially prevent T1D.

Are Regulatory T Cells Defective in Type 1 Diabetes and Can We Fix Them?

Regulatory T cells (Tregs) are critical regulators of peripheral immune tolerance. Treg insufficiency can lead to autoimmune disorders, including type 1 diabetes (T1D). Increasing evidence in mouse models of T1D, as well as other autoimmune disorders, suggests that there are defects in Treg-mediated suppression. Indeed, whereas Treg frequency in the peripheral blood of T1D patients is unaltered, their suppressive abilities are diminished compared with Tregs in healthy controls. Although expression of the transcription factor Foxp3 is a prerequisite for Treg development and function, there are many additional factors that can alter their stability, survival, and function. Much has been learned in other model systems, such as tumors, about the mechanism and pathways that control Treg stability and function. This review poses the question of whether we can use these findings to develop new therapeutic approaches that might boost Treg stability, survival, and/or function in T1D and possibly other autoimmune disorders.

Presence of BPIFB1 in saliva from non-obese diabetic mice

We previously showed that mRNA expression of BPIFB1 (Bpifb1), an antibacterial protein in the palate, lung, and nasal epithelium clone protein family, was increased in parotid acinar cells in non-obese diabetic (NOD, NOD/ShiJcl) mice, which is an animal model for Sjögren's syndrome. However, we did not previously assess the protein levels. In this report, we confirmed the expression of BPIFB1 protein in the parotid glands of NOD mice. Immunoblotting of subcellular fractions revealed that BPIBB1 was localised in secretory granules in parotid glands from NOD mice, and was almost not in parotid glands from the control mice. BPIFB1 had N-linked glycan that reacted with Aleuria aurantia lectin, which caused two types of spots with a slightly different pI and molecular weight. The expression of BPIFB1 protein was also demonstrated by immunohistochemistry. BPIFB1 was detected in the saliva from NOD mice but not in the saliva from the control mice, indicating individual constitution. BPIFB1 in saliva may be applied to other research as a diagnostic marker.

Repurposed JAK1/JAK2 Inhibitor Reverses Established Autoimmune Insulitis in NOD Mice

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

Comparative Pathogenesis of Autoimmune Diabetes in Humans, NOD Mice, and Canines: Has a Valuable Animal Model of Type 1 Diabetes Been Overlooked?

Despite decades of research in humans and mouse models of disease, substantial gaps remain in our understanding of pathogenic mechanisms underlying the development of type 1 diabetes. Furthermore, translation of therapies from preclinical efforts capable of delaying or halting β-cell destruction has been limited. Hence, a pressing need exists to identify alternative animal models that reflect human disease. Canine insulin deficiency diabetes is, in some cases, considered to follow autoimmune pathogenesis, similar to NOD mice and humans, characterized by hyperglycemia requiring lifelong exogenous insulin therapy. Also similar to human type 1 diabetes, the canonical canine disorder appears to be increasing in prevalence. Whereas islet architecture in rodents is distinctly different from humans, canine pancreatic endocrine cell distribution is more similar. Differences in breed susceptibility alongside associations with MHC and other canine immune response genes parallel that of different ethnic groups within the human population, a potential benefit over NOD mice. The impact of environment on disease development also favors canine over rodent models. Herein, we consider the potential for canine diabetes to provide valuable insights for human type 1 diabetes in terms of pancreatic histopathology, impairment of β-cell function and mass, islet inflammation (i.e., insulitis), and autoantibodies specific for β-cell antigens.

Exercise Training but not Curcumin Supplementation Decreases Immune Cell Infiltration in the Pancreatic Islets of a Genetically Susceptible Model of Type 1 Diabetes

Background

The main mechanism involved in the pathogenesis of autoimmunity is an uncontrolled inflammatory response against self-antigens. Therefore, anti-inflammatory factors, such as the intake of bioactive compounds and a physically active lifestyle, may decrease or cease the development of autoimmune diseases. Type 1 diabetes (T1D) is an autoimmune disease characterized by pancreatic β cell destruction. The non-obese diabetic (NOD) mouse is a model of spontaneous T1D and is the model most similar to human disease.

Methods

To determine the effects of exercise training and curcumin supplementation on T1D progression, 48 NOD mice, 5 weeks old, were randomly divided into four groups: control, curcumin supplementation, trained, and trained plus curcumin. Every 2 weeks, blood glucose was measured using a glucometer. At the end of 20 weeks, a histopathological procedure was used to assess immune cells infiltration into pancreatic β cells (insulitis).

Results

Moderate intensity exercise training has the potential to protect pancreatic β cells against an immune response in vivo. However, curcumin supplementation failed to attenuate insulitis in NOD mice.

Conclusions

These data provide evidence that exercise training can mitigate T1D development in genetically susceptible mice.

Development of the Nonobese Diabetic Mouse and Contribution of Animal Models for Understanding Type 1 Diabetes

In 1974, the discovery of a mouse and a rat that spontaneously developed hyperglycemia led to the development of 2 autoimmune diabetes models: nonobese diabetic (NOD) mouse and Bio-Breeding rat. These models have contributed to our understanding of autoimmune diabetes, provided tools to dissect autoimmune islet damage, and facilitated development of early detection, prevention, and treatment of type 1 diabetes. The genetic characterization, monoclonal antibodies, and congenic strains have made NOD mice especially useful.Although the establishment of the inbred NOD mouse strain was documented by Makino et al (Jikken Dobutsu. 1980;29:1-13), this review will focus on the not-as-well-known history leading to the discovery of a glycosuric female mouse by Yoshihiro Tochino. This discovery was spearheaded by years of effort by Japanese scientists from different disciplines and dedicated animal care personnel and by the support of the Shionogi Pharmaceutical Company, Osaka, Japan. The history is based on the early literature, mostly written in Japanese, and personal communications especially with Dr Tochino, who was involved in diabetes animal model development and who contributed to the release of NOD mice to the international scientific community. This article also reviews the scientific contributions made by the Bio-Breeding rat to autoimmune diabetes.

CD137 Plays Both Pathogenic and Protective Roles in Type 1 Diabetes Development in NOD Mice

We previously reported that CD137 (encoded by Tnfrsf9) deficiency suppressed type 1 diabetes (T1D) progression in NOD mice. We also demonstrated that soluble CD137 produced by regulatory T cells contributed to their autoimmune-suppressive function in this model. These results suggest that CD137 can either promote or suppress T1D development in NOD mice depending on where it is expressed. In this study, we show that NOD.Tnfrsf9^-/- CD8 T cells had significantly reduced diabetogenic capacity, whereas absence of CD137 in non-T and non-B cells had a limited impact on T1D progression. In contrast, NOD.Tnfrsf9^-/- CD4 T cells highly promoted T1D development. We further demonstrated that CD137 was important for the accumulation of β cell-autoreactive CD8 T cells but was dispensable for their activation in pancreatic lymph nodes. The frequency of islet-infiltrating CD8 T cells was reduced in NOD.Tnfrsf9^-/- mice in part because of their decreased proliferation. Furthermore, CD137 deficiency did not suppress T1D development in NOD mice expressing the transgenic NY8.3 CD8 TCR. This suggests that increased precursor frequency of β cell-autoreactive CD8 T cells in NY8.3 mice obviated a role for CD137 in diabetogenesis. Finally, blocking CD137-CD137 ligand interaction significantly delayed T1D onset in NOD mice. Collectively, our results indicate that one important diabetogenic function of CD137 is to promote the expansion and accumulation of β cell-autoreactive CD8 T cells, and in the absence of CD137 or its interaction with CD137 ligand, T1D progression is suppressed.

Early differences in islets from prediabetic NOD mice: combined microarray and proteomic analysis

AIMS/HYPOTHESIS

Type 1 diabetes is an endocrine disease where a long preclinical phase, characterised by immune cell infiltration in the islets of Langerhans, precedes elevated blood glucose levels and disease onset. Although several studies have investigated the role of the immune system in this process of insulitis, the importance of the beta cells themselves in the initiation of type 1 diabetes is less well understood. The aim of this study was to investigate intrinsic differences present in the islets from diabetes-prone NOD mice before the onset of insulitis.

METHODS

The islet transcriptome and proteome of 2-3-week-old mice was investigated by microarray and 2-dimensional difference gel electrophoresis (2D-DIGE), respectively. Subsequent analyses using sophisticated pathway analysis and ranking of differentially expressed genes and proteins based on their relevance in type 1 diabetes were performed.

RESULTS

In the preinsulitic period, alterations in general pathways related to metabolism and cell communication were already present. Additionally, our analyses pointed to an important role for post-translational modifications (PTMs), especially citrullination by PAD2 and protein misfolding due to low expression levels of protein disulphide isomerases (PDIA3, 4 and 6), as causative mechanisms that induce beta cell stress and potential auto-antigen generation.

CONCLUSIONS/INTERPRETATION

We conclude that the pancreatic islets, irrespective of immune differences, may contribute to the initiation of the autoimmune process.

DATA AVAILABILITY

All microarray data are available in the ArrayExpress database ( www.ebi.ac.uk/arrayexpress ) under accession number E-MTAB-5264.