Altered B:9–23 Insulin, When Administered Intranasally with Cholera Toxin Adjuvant, Suppresses the Expression of Insulin Autoantibodies and Prevents Diabetes

The impact of the gut microbiome on extra-intestinal autoimmune diseases

The prevalence of autoimmune diseases (ADs) worldwide has rapidly increased over the past few decades. Thus, in addition to the classical risk factors for ADs, such as genetic polymorphisms, infections and smoking, environmental triggers have been considered. Recent sequencing-based approaches have revealed that patients with extra-intestinal ADs, such as multiple sclerosis, rheumatoid arthritis, type 1 diabetes and systemic lupus erythematosus, have distinct gut microbiota compositions compared to healthy controls. Faecal microbiota transplantation or inoculation with specific microbes in animal models of ADs support the hypothesis that alterations of gut microbiota influence autoimmune responses and disease outcome. Here, we describe the compositional and functional changes in the gut microbiota in patients with extra-intestinal AD and discuss how the gut microbiota affects immunity. Moreover, we examine how the gut microbiota might be modulated in patients with ADs as a potential preventive or therapeutic approach.

Single-nucleotide polymorphisms as important risk factors of diabetes among Middle East population

Diabetes is a chronic metabolic disorder that leads to the dysfunction of various tissues and organs, including eyes, kidneys, and cardiovascular system. According to the World Health Organization, diabetes prevalence is 8.8% globally among whom about 90% of cases are type 2 diabetes. There are not any significant clinical manifestations in the primary stages of diabetes. Therefore, screening can be an efficient way to reduce the diabetic complications. Over the recent decades, the prevalence of diabetes has increased alarmingly among the Middle East population, which has imposed exorbitant costs on the health care system in this region. Given that the genetic changes are among the important risk factors associated with predisposing people to diabetes, we examined the role of single-nucleotide polymorphisms (SNPs) in the pathogenesis of diabetes among Middle East population. In the present review, we assessed the molecular pathology of diabetes in the Middle East population that paves the way for introducing an efficient SNP-based diagnostic panel for diabetes screening among the Middle East population. Since, the Middle East has a population of 370 million people; the current review can be a reliable model for the introduction of SNP-based diagnostic panels in other populations and countries around the world.

Insulin immunotherapy for pretype 1 diabetes

PURPOSE OF REVIEW

Loss of tolerance to insulin likely contributes to the immunopathogenesis of type 1 diabetes (T1D). Several large clinical trials and smaller mechanistic studies have failed to demonstrate the efficacy of insulin antigen therapy. The growing awareness of the heterogeneity of T1D likely affects the response to various immune therapies including insulin. Identification of biomarkers of clinical response will provide further insight into mechanisms leading to the disease and classify responders in the quest for personalized therapy.

RECENT FINDINGS

Several biomarkers have identified subpopulations in posthoc analyses that showed benefit from oral insulin even though the placebo-controlled study was as a whole unsuccessful. High insulin autoantibody titer, low first phase insulin response, and high Diabetes Prevention Trial-Type 1 Risk Score identify at-risk relatives more likely to benefit from oral insulin. Future incorporation of human leukocyte antigen and the variable number of tandem repeats polymorphism located in the insulin gene promoter (INS VNTR) is of interest for both primary and secondary prevention studies.

SUMMARY

Although primary and secondary prevention trials using oral insulin are ongoing, those completed have been largely unsuccessful. However, we believe that oral insulin should be considered in future trials as part of combination therapies as prerandomization biomarker testing is refined.

Combining Well-Tempered Metadynamics Simulation and SPR Assays to Characterize the Binding Mechanism of the Universal T-Lymphocyte Tetanus Toxin Epitope TT830-843

Peptide TT830-843 from the tetanus toxin is a universal T-cell epitope. It helps in vaccination and induces T-cell activation. However, the fine molecular interaction between this antigen and the major histocompatibility complex (MHC) remains unknown. Molecular analysis of its interaction with murine MHC (H-2) was proposed to explore its immune response efficiency. Molecular dynamics simulations are important mechanisms for understanding the basis of protein-ligand interactions, and metadynamics is a useful technique for enhancing sampling in molecular dynamics. SPR (surface plasmon resonance) assays were used to validate whether the metadynamics results are in accordance with the experimental results. The peptide TT830-843 unbinding process was simulated, and the free energy surface reconstruction revealed a detailed conformational landscape. The simulation described the exiting path as a stepwise mechanism between progressive detachment states. We pointed out how the terminus regions act as anchors for binding and how the detachment mechanism includes the opening of α-helices to permit the peptide's central region dissociation. The results indicated the peptide/H-2 receptor encounter occurs within a distance lesser than 27.5 Å, and the encounter can evolve to form a stable complex. SPR assays confirmed the complex peptide/H-2 as a thermodynamically stable system, exhibiting enough free energy to interact with TCR on the antigen-presenting cell surface. Therefore, combining in silico and in vitro assays provided significant evidence to support the peptide/H-2 complex formation.

Immune Mechanisms and Pathways Targeted in Type 1 Diabetes

PURPOSE OF REVIEW

The immunosuppressive agent cyclosporine was first reported to lower daily insulin dose and improve glycemic control in patients with new-onset type 1 diabetes (T1D) in 1984. While renal toxicity limited cyclosporine's extended use, this observation ignited collaborative efforts to identify immunotherapeutic agents capable of safely preserving β cells in patients with or at risk for T1D.

RECENT FINDINGS

Advances in T1D prediction and early diagnosis, together with expanded knowledge of the disease mechanisms, have facilitated trials targeting specific immune cell subsets, autoantigens, and pathways. In addition, clinical responder and non-responder subsets have been defined through the use of metabolic and immunological readouts. Herein, we review emerging T1D biomarkers within the context of recent and ongoing T1D immunotherapy trials. We also discuss responder/non-responder analyses in an effort to identify therapeutic mechanisms, define actionable pathways, and guide subject selection, drug dosing, and tailored combination drug therapy for future T1D trials.

Altered Function of Antigen-Presenting Cells in Type 1 Diabetes: A Challenge for Antigen-Specific Immunotherapy?

Type 1 diabetes (T1D) arises from a failure to maintain tolerance to specific β-cell antigens. Antigen-specific immunotherapy (ASIT) aims to reestablish immune tolerance through the supply of pertinent antigens to specific cell types or environments that are suitable for eliciting tolerogenic responses. However, antigen-presenting cells (APCs) in T1D patients and in animal models of T1D are affected by a number of alterations, some due to genetic polymorphism. Combination of these alterations, impacting the number, phenotype, and function of APC subsets, may account for both the underlying tolerance deficiency and for the limited efficacy of ASITs so far. In this comprehensive review, we examine different aspects of APC function that are pertinent to tolerance induction and summarize how they are altered in the context of T1D. We attempt to reconcile 25 years of studies on this topic, highlighting genetic, phenotypic, and functional features that are common or distinct between humans and animal models. Finally, we discuss the implications of these defects and the challenges they might pose for the use of ASITs to treat T1D. Better understanding of these APC alterations will help us design more efficient ways to induce tolerance.

Plant-based vaccines for oral delivery of type 1 diabetes-related autoantigens: Evaluating oral tolerance mechanisms and disease prevention in NOD mice

Autoantigen-specific immunological tolerance represents a central objective for prevention of type 1 diabetes (T1D). Previous studies demonstrated mucosal antigen administration results in expansion of Foxp3+ and LAP+ regulatory T cells (Tregs), suggesting oral delivery of self-antigens might represent an effective means for modulating autoimmune disease. Early preclinical experiments using the non-obese diabetic (NOD) mouse model reported mucosal administration of T1D-related autoantigens [proinsulin or glutamic acid decarboxylase 65 (GAD)] delayed T1D onset, but published data are conflicting regarding dose, treatment duration, requirement for combinatorial agents, and extent of efficacy. Recently, dogma was challenged in a report demonstrating oral insulin does not prevent T1D in NOD mice, possibly due to antigen digestion prior to mucosal immune exposure. We used transplastomic plants expressing proinsulin and GAD to protect the autoantigens from degradation in an oral vaccine and tested the optimal combination, dose, and treatment duration for the prevention of T1D in NOD mice. Our data suggest oral autoantigen therapy alone does not effectively influence disease incidence or result in antigen-specific tolerance assessed by IL-10 measurement and Treg frequency. A more aggressive approach involving tolerogenic cytokine administration and/or lymphocyte depletion prior to oral antigen-specific immunotherapy will likely be required to impart durable therapeutic efficacy.

Antibodies to post-translationally modified insulin in type 1 diabetes

AIM/HYPOTHESIS

Insulin is the most specific beta cell antigen and a potential primary autoantigen in type 1 diabetes. Insulin autoantibodies (IAAs) are the earliest marker of beta cell autoimmunity; however, only slightly more than 50% of children and even fewer adults newly diagnosed with type 1 diabetes are IAA positive. The aim of this investigation was to determine if oxidative post-translational modification (oxPTM) of insulin by reactive oxidants associated with islet inflammation generates neoepitopes that stimulate an immune response in individuals with type 1 diabetes.

METHODS

oxPTM of insulin was generated using ribose and various reactive oxygen species. Modifications were analysed by SDS-PAGE, three-dimensional fluorescence and MS. Autoreactivity to oxPTM insulin (oxPTM-INS) was observed by ELISA and western blotting, using sera from participants with type 1 or type 2 diabetes and healthy controls as probes. IAA was measured using the gold-standard radiobinding assay (RBA).

RESULTS

MS of oxPTM-INS identified chlorination of Tyr16 and Tyr26; oxidation of His5, Cys7 and Phe24; and glycation of Lys29 and Phe1 in chain B. Significantly higher binding to oxPTM-INS vs native insulin was observed in participants with type 1 diabetes, with 84% sensitivity compared with 61% sensitivity for RBA. oxPTM-INS autoantibodies and IAA co-existed in 50% of those with type 1 diabetes. Importantly 34% of those with diabetes who were IAA negative were oxPTM-INS positive. Altogether, 95% of participants with type 1 diabetes presented with autoimmunity to insulin by RBA, oxPTM-INS or both. Binding to oxPTM-INS was directed towards oxPTM-INS fragments with slower mobility than native insulin.

CONCLUSION/INTERPRETATION

These data suggest that oxPTM-INS is a potential autoantigen in individuals with new-onset type 1 diabetes.

Rheumatoid arthritis vaccine therapies: perspectives and lessons from therapeutic ligand epitope antigen presentation system vaccines for models of rheumatoid arthritis

The current status of therapeutic vaccines for autoimmune diseases is reviewed with rheumatoid arthritis as the focus. Therapeutic vaccines for autoimmune diseases must regulate or subdue responses to common self-antigens. Ideally, such a vaccine would initiate an antigen-specific modulation of the T-cell immune response that drives the inflammatory disease. Appropriate animal models and types of T helper cells and signature cytokine responses that drive autoimmune disease are also discussed. Interpretation of these animal models must be done cautiously because the means of initiation, autoantigens, and even the signature cytokine and T helper cell (Th1 or Th17) responses that are involved in the disease may differ significantly from those in humans. We describe ligand epitope antigen presentation system vaccine modulation of T-cell autoimmune responses as a strategy for the design of therapeutic vaccines for rheumatoid arthritis, which may also be effective in other autoimmune conditions.

Antigen presentation in the autoimmune diabetes of the NOD mouse

This paper reviews the presentation of peptides by major histocompatibility complex (MHC) class II molecules in the autoimmune diabetes of the nonobese diabetic (NOD) mouse. Islets of Langerhans contain antigen-presenting cells that capture the proteins and peptides of the beta cells' secretory granules. Peptides bound to I-A(g7), the unique MHC class II molecule of NOD mice, are presented in islets and in pancreatic lymph nodes. The various beta cell-derived peptides interact with selected CD4 T cells to cause inflammation and beta cell demise. Many autoreactive T cells are found in NOD mice, but not all have a major role in the initiation of the autoimmune process. I emphasize here the evidence pointing to insulin autoreactivity as a seminal component in the diabetogenic process.

Oral delivery of human biopharmaceuticals, autoantigens and vaccine antigens bioencapsulated in plant cells

Among 12billion injections administered annually, unsafe delivery leads to >20million infections and >100million reactions. In an emerging new concept, freeze-dried plant cells (lettuce) expressing vaccine antigens/biopharmaceuticals are protected in the stomach from acids/enzymes but are released to the immune or blood circulatory system when plant cell walls are digested by microbes that colonize the gut. Vaccine antigens bioencapsulated in plant cells upon oral delivery after priming, conferred both mucosal and systemic immunity and protection against bacterial, viral or protozoan pathogens or toxin challenge. Oral delivery of autoantigens was effective against complications of type 1 diabetes and hemophilia, by developing tolerance. Oral delivery of proinsulin or exendin-4 expressed in plant cells regulated blood glucose levels similar to injections. Therefore, this new platform offers a low cost alternative to deliver different therapeutic proteins to combat infectious or inherited diseases by eliminating inactivated pathogens, expensive purification, cold storage/transportation and sterile injections.

Immunotherapy trials for type 1 diabetes: the contribution of George Eisenbarth

Type 1 diabetes (T1D) results from the autoimmune destruction of pancreatic β-cells, and as such it should respond to immunotherapy. George Eisenbarth gave many significant contributions to this field. He has been involved at some level in most immunotherapy trials during the past three decades. He was among the pioneers who attempted immunotherapy approaches in patients with recent-onset T1D. In the early 1980s he began studying relatives of those with the disease, leading to the concept that T1D was a chronic autoimmune disease, in which islet autoimmune responses would silently destroy β-cells and cause progressive impairment of insulin secretion, years to months before a diagnosis was made. Consequently, he was one of the first to attempt immune intervention in people at high risk of T1D. Throughout his career he developed autoantibody assays and predictive models (which included metabolic testing and later genetics) to identify individuals at risk of T1D. He provided seminal intellectual contributions and critical tools for prevention trials. His focus on insulin as a critical autoantigen led to multiple prevention trials, including the Diabetes Prevention Trial-Type 1 (DPT-1), which studied both parenteral and oral insulin. In the DPT-1 Oral Insulin Trial, a cohort with higher levels of insulin autoantibodies was identified that appeared to have delayed disease progression. Type 1 Diabetes TrialNet is conducting a new trial to verify or refute this observation. Moreover, George identified and tested in the mouse small molecules that block or modulate presentation of a key insulin peptide and in turn prevent the activation of insulin-specific T-lymphocytes. Thus, we believe his greatest contribution is yet to come, as in the near future we should see this most recent work translate into clinical trials.

Peptide-based approaches to treat lupus and other autoimmune diseases

After a long period where the potential of therapeutic peptides was let into oblivion and even dismissed, there is a revival of interest in peptides as potential drug candidates. Novel strategies for limiting metabolism and improve their bioavailability, and alternative routes of administration have emerged. This resulted in a large number of peptide-based drugs that are now being marketed in different indications. Regarding autoimmunity, successful data have been reported in numerous mouse models of autoimmune inflammation, yet relatively few clinical trials based on synthetic peptides are currently underway. This review reports on peptides that show much promises in appropriate mouse models of autoimmunity and describes in more detail clinical trials based on peptides for treating autoimmune patients. A particular emphasis is given to the 21-mer peptide P140/Lupuzor that has completed successfully phase I, phase IIa and phase IIb clinical trials for systemic lupus erythematosus.

The effect of regulatory T-cell depletion on the spectrum of organ-specific autoimmune diseases in nonobese diabetic mice at different ages

The nonobese diabetic (NOD) mouse spontaneously develops several autoimmune diseases, including type 1 diabetes and to a lesser extent thyroiditis and sialitis. Imbalance between effector T cells (Teffs) and regulatory T cells (Tregs) has recently been proposed as a mechanism for the disease pathogenesis in NOD mice, but previous studies have shown the various outcomes by different timing and methods of Treg-depletion. This study was, therefore, designed to compare the consequences of Treg-depletion by the same method (anti-CD25 antibody) on the spectrum of organ-specific autoimmune diseases in NOD mice of different ages. Treg-depletion by anti-CD25 antibody at 10 days of age accelerated development of all three diseases we examined (insulitis/diabetes, thyroiditis, and sialitis); Treg-depletion at 4 weeks of age accelerated only diabetes but not thyroiditis or sialitis; and Treg-depletion at 12 weeks of age hastened only development of thyroiditis and exhibited little influence on diabetes or sialitis. Increased levels of insulin autoantibodies (IAA) were, however, observed in mice depleted of Tregs at 10 days of age, not in those at 4 weeks. Thus, the consequences of Treg-depletion on the spectrum of organ-specific autoimmune diseases depend on the timing of anti-CD25 antibody injection in NOD mice. Aging gradually tips balance between Teffs and Tregs toward Teff-dominance for diabetes, but this balance for thyroiditis and sialitis likely alters more intricately. Our data also suggest that the levels of IAA are not necessarily correlated with diabetes development.

Virtual optimization of nasal insulin therapy predicts immunization frequency to be crucial for diabetes protection

OBJECTIVE

Development of antigen-specific strategies to treat or prevent type 1 diabetes has been slow and difficult because of the lack of experimental tools and defined biomarkers that account for the underlying therapeutic mechanisms.

RESEARCH DESIGN AND METHODS

The type 1 diabetes PhysioLab platform, a large-scale mathematical model of disease pathogenesis in the nonobese diabetic (NOD) mouse, was used to investigate the possible mechanisms underlying the efficacy of nasal insulin B:9-23 peptide therapy. The experimental aim was to evaluate the impact of dose, frequency of administration, and age at treatment on Treg induction and optimal therapeutic outcome.

RESULTS

In virtual NOD mice, treatment efficacy was predicted to depend primarily on the immunization frequency and stage of the disease and to a lesser extent on the dose. Whereas low-frequency immunization protected from diabetes atrributed to Treg and interleukin (IL)-10 induction in the pancreas 1-2 weeks after treatment, high-frequency immunization failed. These predictions were confirmed with wet-lab approaches, where only low-frequency immunization started at an early disease stage in the NOD mouse resulted in significant protection from diabetes by inducing IL-10 and Treg.

CONCLUSIONS

Here, the advantage of applying computer modeling in optimizing the therapeutic efficacy of nasal insulin immunotherapy was confirmed. In silico modeling was able to streamline the experimental design and to identify the particular time frame at which biomarkers associated with protection in live NODs were induced. These results support the development and application of humanized platforms for the design of clinical trials (i.e., for the ongoing nasal insulin prevention studies).

Suppression of dendritic cell activation by diabetes autoantigens linked to the cholera toxin B subunit

Antigen presenting cells, specifically dendritic cells (DCs) are a focal point in the delicate balance between T cell tolerance and immune responses contributing to the onset of type I diabetes (T1D). Weak adjuvant proteins like the cholera toxin B subunit when linked to autoantigens may sufficiently alter the balance of this initial immune response to suppress the development of autoimmunity. To assess adjuvant enhancement of autoantigen mediated immune suppression of Type 1 diabetes, we examined the cholera toxin B subunit (CTB)-proinsulin fusion protein (CTB-INS) activation of immature dendritic cells (iDC) at the earliest detectable stage of the human immune response. In this study, Incubation of human umbilical cord blood monocyte-derived immature DCs with CTB-INS autoantigen fusion protein increased the surface membrane expression of DC Toll-like receptor (TLR-2) while no significant upregulation in TLR-4 expression was detected. Inoculation of iDCs with CTB stimulated the biosynthesis of both CD86 and CD83 co-stimulatory factors demonstrating an immunostimulatory role for CTB in both DC activation and maturation. In contrast, incubation of iDCs with proinsulin partially suppressed CD86 co-stimulatory factor mediated DC activation, while incubation of iDCs with CTB-INS fusion protein completely suppressed iDC biosynthesis of both CD86 and CD83 costimulatory factors. The incubation of iDCs with increasing amounts of insulin did not increase the level of immune suppression but rather activated DC maturation by stimulating increased biosynthesis of both CD86 and CD83 costimulatory factors. Inoculation of iDCs with CTB-INS fusion protein dramatically increased secretion of the immunosuppressive cytokine IL-10 and suppressed synthesis of the pro-inflammatory cytokine IL12/23 p40 subunit protein suggesting that linkage of CTB to insulin (INS) may play an important role in mediating DC guidance of cognate naïve Th0 cell development into immunosuppressive T lymphocytes. Taken together, the experimental data suggests Toll like receptor 2 (TLR-2) plays a dominant role in CTB mediated INS inhibition of DC induced type 1 diabetes onset in human Type 1 diabetes autoimmunity. Further, fusion of CTB to the autoantigen was found to be essential for enhancement of immune suppression as co-delivery of CTB and insulin did not significantly inhibit DC costimulatory factor biosynthesis. The experimental data presented supports the hypotheses that adjuvant enhancement of autoantigen mediated suppression of islet beta cell inflammation is dependent on CTB stimulation of dendritic cell TLR2 receptor activation and co-processing of both CTB and the autoantigen in the same dendritic cell.

Subcutaneous insulin B:9-23/IFA immunisation induces Tregs that control late-stage prediabetes in NOD mice through IL-10 and IFNgamma

AIMS/HYPOTHESIS

Subcutaneous immunisation with the 9-23 amino acid region of the insulin B chain (B:9-23) in incomplete Freund's adjuvant (IFA) can protect the majority of 4- to 6-week-old prediabetic NOD mice and is currently in clinical trials. Here we analysed the effect of B:9-23/IFA immunisation at later stages of the disease and the underlying mechanisms.

METHODS

NOD mice were immunised once s.c. with B:9-23/IFA at 5 or 9 weeks of age, or when blood glucose reached 10 mmol/l or higher. Diabetes incidence was followed in addition to variables such as regulatory T cell (Treg) induction, cytokine production (analysed by Elispot) and emergence of pathogenic CD8(+)/NRP-V7(+) cells.

RESULTS

A single B:9-23/IFA immunisation protected the majority of NOD mice at advanced stages of insulitis, but not after blood glucose reached 13.9 mmol/l. It increased Treg numbers and lost its protective effect after IFNgamma or IL-10 neutralisation, but not in the absence of IL-4. CD4(+)CD25(+) and to a lesser extent IFNgamma-producing cells from mice protected by B:9-23/IFA induced tolerance upon transfer into new NOD animals, indicating that a dominant Treg-mediated effect was operational. Reduced numbers of CD8(+)/NRP-V7(+) memory T cells coincided with protection from the disease.

CONCLUSIONS/INTERPRETATION

Protection from diabetes after B:9-23/IFA immunisation cannot be achieved once diabetes is fully established, but can be achieved at most prediabetic stages of the disease. Protection is mediated by Tregs that require IFNgamma and IL-10. These findings should provide important guidance for ongoing human trials, especially for the development of suitable T cell biomarkers.

[Antitumor effects of raddeanin A on S180, H22 and U14 cell xenografts in mice]

BACKGROUND & OBJECTIVE

Raddeanin A, a triterpenoid saponin from Anemone raddeana Regel, has good antitumor activity in vitro. This study was to investigate its antitumor effects on tumor cell xenografts in mice.

METHODS

The inhibitory effects of raddeanin A on the proliferation of human nasopharyngeal carcinoma KB cells and ovarian cancer SKOV3 cells were measured by MTT assay. The inhibitory effects of raddeanin A injection on the growth of sarcoma S180, liver cancer H22 and cervical carcinoma U14 cell xenografts in mice and the effect of raddeanin A lavage on the growth of S180 cell xenografts were measured. The acute toxicity of raddeanin A was also measured.

RESULTS

The 50% inhibition concentration (IC(50)) of raddeanin A was 4.64 microg/mL for KB cells and 1.40 microg/mL for SKOV3 cells. When injected with raddeanin A at a dose of 4.5 mg/kg, the growth inhibition rates of S180, H22 and U14 cell xenografts were 60.5%, 36.2% and 61.8%, respectively. When lavaged with raddeanin A at a dose of 200 mg/kg, the growth inhibition rate of S180 cell xenografts was 64.7%. The median lethal dose (LD50) of raddeanin A lavage was 1.1 g/kg and that of raddeanin A injection was 16.1 mg/kg.

CONCLUSION

Raddeanin A has good antitumor activity both in vitro and in vivo, and would be a potential antitumor medicine.

The anti-insulin trimolecular complex in type 1 diabetes

PURPOSE OF REVIEW

Description of the immunologic components needed for autoimmune diabetes.

RECENT FINDINGS

The major histocompatability complex (MHC) class II molecules are the primary susceptibility genes for many autoimmune diseases, including type 1 diabetes. Understanding of the structural interaction between MHC molecules, antigenic peptides, and T-cell receptors (the three components of the trimolecular complex) has increased greatly over the past several years. The components of the anti-insulin trimolecular complex and findings that insulin is a key autoantigen in type 1 diabetes are reviewed.

SUMMARY

The anti-insulin trimolecular complex is well defined in the nonobese diabetic mouse model. Insulin and specifically, the amino acid sequence 9 to 23 of the insulin B chain, represents a primary antigenic target for islet autoimmunity in the nonobese diabetic mouse model of type 1 diabetes with a specific mutation of this peptide preventing all diabetes. Initial studies suggest the human homologs of the anti-insulin trimolecular complex may be relevant in human disease.

AB toxins: a paradigm switch from deadly to desirable

To ensure their survival, a number of bacterial and plant species have evolved a common strategy to capture energy from other biological systems. Being imperfect pathogens, organisms synthesizing multi-subunit AB toxins are responsible for the mortality of millions of people and animals annually. Vaccination against these organisms and their toxins has proved rather ineffective in providing long-term protection from disease. In response to the debilitating effects of AB toxins on epithelial cells of the digestive mucosa, mechanisms underlying toxin immunomodulation of immune responses have become the focus of increasing experimentation. The results of these studies reveal that AB toxins may have a beneficial application as adjuvants for the enhancement of immune protection against infection and autoimmunity. Here, we examine similarities and differences in the structure and function of bacterial and plant AB toxins that underlie their toxicity and their exceptional properties as immunomodulators for stimulating immune responses against infectious disease and for immune suppression of organ-specific autoimmunity.

Insulin auto-immunity: implications for the prevention of Type 1 diabetes mellitus

Mounting evidence suggests insulin is an important and potentially initiating antigen in the pathogenesis of Type 1 diabetes. High-affinity insulin antibodies are found early in disease development and appear to predict progression. Insulin is the only Type 1 diabetes auto-antigen with exclusive pancreatic expression and the only one whose gene maps to a major susceptibility locus. Preclinical studies in rodent models of immune-mediated diabetes show great promise for the possibility of preventing disease by peripheral tolerization. Translation of this evidence to clinical trials of oral, intranasal and parenteral insulin to invoke immune tolerance and prevent diabetes has not proven successful to date, but promising results in a small subset of highest-risk individuals have maintained enthusiasm for this promising prevention strategy. Currently, studies of oral and intranasal insulin are ongoing to determine the optimal dose, timing and target population for Type 1 diabetes prevention.

Banting Lecture 2009: An unfinished journey: molecular pathogenesis to prevention of type 1A diabetes

The Banting Medal for Scientific Achievement Award is the American Diabetes Association's highest scientific award and honors an individual who has made significant, long-term contributions to the understanding of diabetes, its treatment, and/or prevention. The award is named after Nobel Prize winner Sir Frederick Banting, who codiscovered insulin treatment for diabetes.

Dr. Eisenbarth received the American Diabetes Association's Banting Medal for Scientific Achievement at the Association's 69th Scientific Sessions, June 5–9, 2009, in New Orleans, Louisiana. He presented the Banting Lecture, An Unfinished Journey—Type 1 Diabetes—Molecular Pathogenesis to Prevention , on Sunday, June 7, 2009.

Nucleic acid-associated autoantigens: pathogenic involvement and therapeutic potential

Autoimmunity to ubiquitously expressed macromolecular nucleic acid-protein complexes such as the nucleosome or the spliceosome is a characteristic feature of systemic autoimmune diseases. Disease-specificity and/or association with clinical features of some of these autoimmune responses suggest pathogenic involvement which, however, has been proven in only a few cases so far. Although the mechanisms leading to autoimmunity against nucleic acid-containing complexes are still far from being fully understood, there is increasing experimental evidence that the nucleic acid component may act as a co-stimulator or adjuvans via activation of nucleic acid-binding receptor systems such as Toll-like receptors in antigen-presenting cells. Dysregulated apoptosis and inappropriate stimulation of nucleic acid-sensing receptors may lead to loss of tolerance against the protein components of such complexes, activation of autoreactive T cells and formation of autoantibodies. This has been demonstrated to occur in systemic lupus erythematosus and seems to represent a general mechanism that may be crucial for the development of systemic autoimmune diseases. This review provides a comprehensive overview of the most thoroughly-characterized nucleic acid-associated autoantigens, describing their structure and biological function, as well as the nature and pathogenic importance of the reactivities directed against them. Furthermore, recent advances in immunotherapy such as antigen-specific approaches targeted at nucleic acid-binding antigens are discussed.

[Antigen specific treatment for the inhibition and remission of type 1 diabetes]

Treatment with anti-CD3 antibodies appears promising to preserve residual beta-cell function in recent onset type 1 diabetes although many patients had therapy related adverse events. Insulin is an important islet antigen and autoimmunity to insulin may be central to disease pathogenesis of type 1 diabetes in man and NOD mouse. Evidence is strongest for the NOD mouse model, where blocking immune responses to insulin by amino acid substitution at positions B: 16, prevents diabetes. Insulin can be used to immunologically prevent diabetes of NOD mice, however, insulin-based preventive immunoregulation of diabetes in man is not yet possible. Treatment of NOD mice with insulin B-chain peptide and poly I: C, a Toll-like receptor 3 ligand, induces the pathogenic T cells as well as regulatory T cells and recruits them into the islets. Intranasal treatment with insulin B-chain analogue peptide with amino acid substitutions at positions B: 16 and 19 prevented the progression to diabetes and induced remission from hyperglycemia when co-administered with a mucosal adjuvant cholera toxin. Thus, an antigenic peptide vaccination with an alternative adjuvant or route might induce antigen-specific regulatory cell populations rather than pathogenic T cells. We believe that such an improved antigen specific therapy could provide more efficient and safer disease suppression and remission for human type 1 diabetes.

Activation of insulin-reactive CD8 T-cells for development of autoimmune diabetes

OBJECTIVE

We have previously reported a highly diabetogenic CD8 T-cell clone, G9C8, in the nonobese diabetic (NOD) mouse, specific to low-avidity insulin peptide B15-23, and cells responsive to this antigen are among the earliest islet infiltrates. We aimed to study the selection, activation, and development of the diabetogenic capacity of these insulin-reactive T-cells.

RESEARCH DESIGN AND METHODS

We generated a T-cell receptor (TCR) transgenic mouse expressing the cloned TCR Valpha18/Vbeta6 receptor of the G9C8 insulin-reactive CD8 T-cell clone. The mice were crossed to TCRCalpha-/- mice so that the majority of the T-cells expressed the clonotypic TCR, and the phenotype and function of the cells was investigated.

RESULTS

There was good selection of CD8 T-cells with a predominance of CD8 single-positive thymocytes, in spite of thymic insulin expression. Peripheral lymph node T-cells had a naïve phenotype (CD44lo, CD62Lhi) and proliferated to insulin B15-23 peptide and to insulin. These cells produced interferon-gamma and tumor necrosis factor-alpha in response to insulin peptide and were cytotoxic to insulin peptide-coated targets. In vivo, the TCR transgenic mice developed insulitis but not spontaneous diabetes. However, the mice developed diabetes on immunization, and the activated transgenic T-cells were able to transfer diabetes to immunodeficient NOD.scid mice.

CONCLUSIONS

Autoimmune CD8 T-cells responding to a low-affinity insulin B-chain peptide escape from thymic negative selection and require activation in vivo to cause diabetes.

Genetic association between the interleukin-2 receptor-alpha gene and mode of onset of type 1 diabetes in the Japanese population

CONTEXT/OBJECTIVE

The IL-2 receptor-alpha (IL2RA), also known as CD25, is expressed on the regulatory T cells, which play an important role in the control of immune responses and the maintenance of immune homeostasis. Our objective was to determine whether variants in the IL2RA gene are associated with type 1 diabetes in the Japanese population.

DESIGN/PATIENTS

We genotyped the four single-nucleotide polymorphisms (rs706778, rs3118470, ss52580101, and rs11594656) of the IL2RA in 885 patients with type 1 diabetes and 606 control subjects of Japanese origin. The allele and genotype frequencies were examined in the patient groups stratified by their mode of onset in a case-control study.

RESULTS

We found evidence of association with acute-onset, but not slow-onset and fulminant, type 1 diabetes for two of the four single-nucleotide polymorphisms genotyped (rs706778 and rs3118470). The rs706778 A allele and the rs3118470 G allele were associated with an increased disease risk [odds ratio (OR) for rs706778 AA genotype 1.54, P = 4.2 x 10(-4) and OR for rs3118470 GG genotype 1.50, P = 0.0019, respectively]. Furthermore, the A-G haplotype was associated with increased type 1 diabetes risk in the acute-onset form (OR 1.30, P = 0.002).

CONCLUSIONS

The present data confirm the type 1 diabetes association with IL2RA and provide evidence that the different contributions of the IL2RA in the susceptibility to acute-onset and other forms of type 1 diabetes in the Japanese population.

Combined insulin B:9-23 self-peptide and polyinosinic-polycytidylic acid accelerate insulitis but inhibit development of diabetes by increasing the proportion of CD4+Foxp3+ regulatory T cells in the islets in non-obese diabetic mice

Insulin peptide B:9-23 is a major autoantigen in type 1 diabetes. Combined treatment with B:9-23 peptide and polyinosinic-polycytidylic acid (poly I:C), but neither alone, induce insulitis in normal BALB/c mice. In contrast, the combined treatment accelerated insulitis, but prevented diabetes in NOD mice. Our immunofluorescence study with anti-CD4/anti-Foxp3 revealed that the proportion of Foxp3 positive CD4(+)CD25(+) regulatory T cells (Tregs) was elevated in the islets of NOD mice treated with B:9-23 peptide and poly I:C, as compared to non-treated mice. Depletion of Tregs by anti-CD25 antibody hastened spontaneous development of diabetes in non-treated NOD mice, and abolished the protective effect of the combined treatment and conversely accelerated the onset of diabetes in the treated mice. These results indicate that poly I:C combined with B:9-23 peptide promotes infiltration of both pathogenic T cells and predominantly Tregs into the islets, thereby inhibiting progression from insulitis to overt diabetes in NOD mice.