Diabetes-prone NOD mice are resistant to Mycobacterium avium and the infection prevents autoimmune disease

Cracking the type 1 diabetes code: Genes, microbes, immunity, and the early life environment

Type 1 diabetes (T1D) results from a complex interplay of genetic predisposition, immunological dysregulation, and environmental triggers, that culminate in the destruction of insulin-secreting pancreatic β cells. This review provides a comprehensive examination of the multiple factors underpinning T1D pathogenesis, to elucidate key mechanisms and potential therapeutic targets. Beginning with an exploration of genetic risk factors, we dissect the roles of human leukocyte antigen (HLA) haplotypes and non-HLA gene variants associated with T1D susceptibility. Mechanistic insights gleaned from the NOD mouse model provide valuable parallels to the human disease, particularly immunological intricacies underlying β cell-directed autoimmunity. Immunological drivers of T1D pathogenesis are examined, highlighting the pivotal contributions of both effector and regulatory T cells and the multiple functions of B cells and autoantibodies in β-cell destruction. Furthermore, the impact of environmental risk factors, notably modulation of host immune development by the intestinal microbiome, is examined. Lastly, the review probes human longitudinal studies, unveiling the dynamic interplay between mucosal immunity, systemic antimicrobial antibody responses, and the trajectories of T1D development. Insights garnered from these interconnected factors pave the way for targeted interventions and the identification of biomarkers to enhance T1D management and prevention strategies.

Fecal microbiota transplantation for the management of autoimmune diseases: Potential mechanisms and challenges

Autoimmune diseases (AIDs) are a series of immune-mediated lethal diseases featured by over-activated immune cells attacking healthy self-tissues and organs due to the loss of immune tolerance, which always causes severe irreversible systematical organ damage and threatens human health heavily. To date, there are still no definitive cures for the treatment of AIDs due to their pathogenesis has not been clearly understood. Besides, the current clinical treatments of AIDs majorly rely on glucocorticoids and immune suppressors, which can lead to serious side effects. In the past years, there are increasing studies demonstrating that an imbalance of gut microbiota is intimately related to the pathogenesis of various AIDs, shedding light on the development of therapeutics by targeting the gut microbiota for the management of AIDs. Among all the approaches targeting the gut microbiota, fecal microbiota transplantation (FMT) has attracted increasing interest, and it has been proposed as a possible strategy to intervene in the homeostasis of gut microbiota for the treatment of various diseases. However, despite the reported good curative effects and clinical studies conducted on FMT, the detailed mechanisms of FMT for the effective treatment of those diseases have not been figured out. To fully understand the mechanisms of the therapeutic effects of FMT on AIDs and improve the therapeutic efficacy of FMT treatment, a systematic review of this topic is necessary. Hence, in this review paper, the potential mechanisms of FMT for the treatment of various AIDs were summarized, including promotion, shaping, activation, or inhibition of the host immune system via the interactions between the microorganisms and the gut immune system, gut-brain, gut-liver, gut-kidney axis, and so on. Then, applications of FMT for the treatment of various AIDs were detailed presented. Finally, the current challenges and potential solutions for the development of FMT formulations and FMT therapeutics were comprehensively discussed.

Heat shock proteins: Biological functions, pathological roles, and therapeutic opportunities

The heat shock proteins (HSPs) are ubiquitous and conserved protein families in both prokaryotic and eukaryotic organisms, and they maintain cellular proteostasis and protect cells from stresses. HSP protein families are classified based on their molecular weights, mainly including large HSPs, HSP90, HSP70, HSP60, HSP40, and small HSPs. They function as molecular chaperons in cells and work as an integrated network, participating in the folding of newly synthesized polypeptides, refolding metastable proteins, protein complex assembly, dissociating protein aggregate dissociation, and the degradation of misfolded proteins. In addition to their chaperone functions, they also play important roles in cell signaling transduction, cell cycle, and apoptosis regulation. Therefore, malfunction of HSPs is related with many diseases, including cancers, neurodegeneration, and other diseases. In this review, we describe the current understandings about the molecular mechanisms of the major HSP families including HSP90/HSP70/HSP60/HSP110 and small HSPs, how the HSPs keep the protein proteostasis and response to stresses, and we also discuss their roles in diseases and the recent exploration of HSP related therapy and diagnosis to modulate diseases. These research advances offer new prospects of HSPs as potential targets for therapeutic intervention.

The Pathophysiological Role of Heat Shock Response in Autoimmunity: A Literature Review

Within the last two decades, there has been increasing evidence that heat-shock proteins can have a differential influence on the immune system. They can either provoke or ameliorate immune responses. This review focuses on outlining the stimulatory as well as the inhibitory effects of heat-shock proteins 27, 40, 70, 65, 60, and 90 in experimental and clinical autoimmune settings.

Immunotherapeutic Activities of a DNA Plasmid Carrying the Mycobacterial hsp65 Gene (DNAhsp65)

DNA vaccines have become relevant subject matter, and efforts for their development have been increasing due to their potential as technology platforms applicable for prophylactic and therapeutic approaches for infectious diseases and for cancer treatment, allergies, and autoimmune diseases. This review aimed to summarize current knowledge about the plasmid DNA vaccine carrying the mycobacterial hsp65 gene (DNAhsp65), which demonstrates immunomodulatory and immunoregulatory properties of both the innate and adaptive immune systems. The possible mechanisms associated with the modulation and regulatory role of DNAhsp65 in the control of various conditions is also discussed.

The hygiene hypothesis in autoimmunity: the role of pathogens and commensals

The incidence of autoimmune diseases has been steadily rising. Concomitantly, the incidence of most infectious diseases has declined. This observation gave rise to the hygiene hypothesis, which postulates that a reduction in the frequency of infections contributes directly to the increase in the frequency of autoimmune and allergic diseases. This hypothesis is supported by robust epidemiological data, but the underlying mechanisms are unclear. Pathogens are known to be important, as autoimmune disease is prevented in various experimental models by infection with different bacteria, viruses and parasites. Gut commensal bacteria also play an important role: dysbiosis of the gut flora is observed in patients with autoimmune diseases, although the causal relationship with the occurrence of autoimmune diseases has not been established. Both pathogens and commensals act by stimulating immunoregulatory pathways. Here, I discuss the importance of innate immune receptors, in particular Toll-like receptors, in mediating the protective effect of pathogens and commensals on autoimmunity.

Candidate SNP Markers of Gender-Biased Autoimmune Complications of Monogenic Diseases Are Predicted by a Significant Change in the Affinity of TATA-Binding Protein for Human Gene Promoters

Some variations of human genome [for example, single nucleotide polymorphisms (SNPs)] are markers of hereditary diseases and drug responses. Analysis of them can help to improve treatment. Computer-based analysis of millions of SNPs in the 1000 Genomes project makes a search for SNP markers more targeted. Here, we combined two computer-based approaches: DNA sequence analysis and keyword search in databases. In the binding sites for TATA-binding protein (TBP) in human gene promoters, we found candidate SNP markers of gender-biased autoimmune diseases, including rs1143627 [cachexia in rheumatoid arthritis (double prevalence among women)]; rs11557611 [demyelinating diseases (thrice more prevalent among young white women than among non-white individuals)]; rs17231520 and rs569033466 [both: atherosclerosis comorbid with related diseases (double prevalence among women)]; rs563763767 [Hughes syndrome-related thrombosis (lethal during pregnancy)]; rs2814778 [autoimmune diseases (excluding multiple sclerosis and rheumatoid arthritis) underlying hypergammaglobulinemia in women]; rs72661131 and rs562962093 (both: preterm delivery in pregnant diabetic women); and rs35518301, rs34166473, rs34500389, rs33981098, rs33980857, rs397509430, rs34598529, rs33931746, rs281864525, and rs63750953 (all: autoimmune diseases underlying hypergammaglobulinemia in women). Validation of these predicted candidate SNP markers using the clinical standards may advance personalized medicine.

TLR2- and Dectin 1-associated innate immune response modulates T-cell response to pancreatic β-cell antigen and prevents type 1 diabetes

The progression of autoimmune diseases is dictated by deviations in the fine balance between proinflammatory versus regulatory responses, and pathogen recognition receptors (PRRs) play a key role in maintaining this balance. Previously, we have reported that ligation of Toll-like receptor 2 (TLR2) and Dectin 1 on antigen-presenting cells by zymosan results in a regulatory immune response that prevents type 1 diabetes (T1D). Here, we show that TLR2 and Dectin 1 engagement by zymosan promotes regulatory T-cell (Treg) responses against the pancreatic β-cell-specific antigen (Ag). Unlike the TLR4 ligand, bacterial lipopolysaccharide, which induced proinflammatory cytokines and pathogenic T cells, zymosan induced a mixture of pro- and anti-inflammatory factors and Tregs, both in vitro and in vivo. Ag-specific T cells that are activated using zymosan-exposed dendritic cells (DCs) expressed Foxp3 and produced large amounts of IL-10, TGF-β1, and IL-17. NOD mice that received β-cell-Ag-loaded, zymosan-exposed DCs showed delayed hyperglycemia. Injection of NOD mice at the prediabetic age and early hyperglycemic stage with β-cell-Ag, along with zymosan, results in a superior protection of the NOD mice from diabetes as compared with mice that received zymosan alone. This therapeutic effect was associated with increased frequencies of IL-10-, IL-17-, IL-4-, and Foxp3-positive T cells, especially in the pancreatic lymph nodes. These results show that zymosan can be used as an immune regulatory adjuvant for modulating the T-cell response to pancreatic β-cell-Ag and reversing early-stage hyperglycemia in T1D.

Immune evasion, immunopathology and the regulation of the immune system

Costs and benefits of the immune response have attracted considerable attention in the last years among evolutionary biologists. Given the cost of parasitism, natural selection should favor individuals with the most effective immune defenses. Nevertheless, there exists huge variation in the expression of immune effectors among individuals. To explain this apparent paradox, it has been suggested that an over-reactive immune system might be too costly, both in terms of metabolic resources and risks of immune-mediated diseases, setting a limit to the investment into immune defenses. Here, we argue that this view neglects one important aspect of the interaction: the role played by evolving pathogens. We suggest that taking into account the co-evolutionary interactions between the host immune system and the parasitic strategies to overcome the immune response might provide a better picture of the selective pressures that shape the evolution of immune functioning. Integrating parasitic strategies of host exploitation can also contribute to understand the seemingly contradictory results that infection can enhance, but also protect from, autoimmune diseases. In the last decades, the incidence of autoimmune disorders has dramatically increased in wealthy countries of the northern hemisphere with a concomitant decrease of most parasitic infections. Experimental work on model organisms has shown that this pattern may be due to the protective role of certain parasites (i.e., helminths) that rely on the immunosuppression of hosts for their persistence. Interestingly, although parasite-induced immunosuppression can protect against autoimmunity, it can obviously favor the spread of other infections. Therefore, we need to think about the evolution of the immune system using a multidimensional trade-off involving immunoprotection, immunopathology and the parasitic strategies to escape the immune response.

Helminth mediated modulation of Type 1 diabetes (T1D)

Type 1 diabetes is increasing dramatically in incidence in the developed world. While there may be several reasons for this, improved sanitation and public health measures have altered our interactions with certain infectious agents such as helminths. There is increasing interest in the use of helminths or their products to alleviate inflammatory or allergic conditions. Using rodent models of diabetes, it has been possible to explore the therapeutic potential of both live infections as well as helminth-derived products on the development of autoimmunity. This review provides an overview of the findings from animal models and additionally explores the potential for translation to the clinic.

Prevention or acceleration of type 1 diabetes by viruses

Type 1 diabetes is an autoimmune disease characterized by the destruction of insulin-producing pancreatic β-cells. Even though extensive scientific research has yielded important insights into the immune mechanisms involved in pancreatic β-cell destruction, little is known about the events that trigger the autoimmune process. Recent epidemiological and experimental data suggest that environmental factors are involved in this process. In this review, we discuss the role of viruses as an environmental factor on the development of type 1 diabetes, and the immune mechanisms by which they can trigger or protect against this pathology.

Helminth infection and type 1 diabetes

The increasing incidence of type 1 diabetes (T1D) and autoimmune diseases in industrialized countries cannot be exclusively explained by genetic factors. Human epidemiological studies and animal experimental data provide accumulating evidence for the role of environmental factors, such as infections, in the regulation of allergy and autoimmune diseases. The hygiene hypothesis has formally provided a rationale for these observations, suggesting that our co-evolution with pathogens has contributed to the shaping of the present-day human immune system. Therefore, improved sanitation, together with infection control, has removed immunoregulatory mechanisms on which our immune system may depend. Helminths are multicellular organisms that have developed a wide range of strategies to manipulate the host immune system to survive and complete their reproductive cycles successfully. Immunity to helminths involves profound changes in both the innate and adaptive immune compartments, which can have a protective effect in inflammation and autoimmunity. Recently, helminth-derived antigens and molecules have been tested in vitro and in vivo to explore possible applications in the treatment of inflammatory and autoimmune diseases, including T1D. This exciting approach presents numerous challenges that will need to be addressed before it can reach safe clinical application. This review outlines basic insight into the ability of helminths to modulate the onset and progression of T1D, and frames some of the challenges that helminth-derived therapies may face in the context of clinical translation.

PD-L1 blockade overrides Salmonella typhimurium-mediated diabetes prevention in NOD mice: no role for Tregs

Increasingly, evidence suggests that there is a strong environmental component to the development of the autoimmune disease type 1 diabetes. Our previous data showed that NOD mice are protected from developing diabetes after infection with Salmonella typhimurium and there is some evidence that changes within the DC compartment play a crucial role in this protective effect. This paper further characterises this Salmonella-modulated protective phenotype. We find that, contrary to other infection-mediated models of type 1 diabetes protection, there was no expansion of Foxp3(+) Tregs. Furthermore, transcriptome analysis of DCs identified a distinct Salmonella-induced signature in which the inhibitory receptor PD-L1 was up-regulated. This was confirmed by flow cytometry. In vivo blockade of the PD1/PD-L1 interaction was found to ablate the protective function of Salmonella infection. These data provide evidence for a novel regulatory DC phenotype proficient at controlling autoreactive T cells for an extended duration in the NOD mouse model of diabetes.

OdDHL inhibits T cell subset differentiation and delays diabetes onset in NOD mice

Some infectious diseases have been shown to halt the onset of autoimmune disease in animal models and have been suggested to also influence autoimmune pathology in humans. The isolation and study of small molecules and proteins from the infectious agents responsible for the protective effect will enable a mechanistic understanding of how these components may prevent or delay the onset of autoimmunity. In this study we confirm that the quorum-sensing signal molecule OdDHL from Pseudomonas aeruginosa can delay the onset of type 1 diabetes in the NOD mouse model. Furthermore, using an antigen-presenting cell-free system, we find not only that OdDHL inhibits the proliferation of naïve T cells but also that it directly inhibits the differentiation of T cell subsets. OdDHL was shown to have no effect on the inhibition of primed and committed differentiated T cell responses, suggesting that that immune mechanism mediated by this molecule may be more restricted to initial stages of infection.

An update on the use of NOD mice to study autoimmune (Type 1) diabetes

The widely used nonobese diabetic (NOD) mouse model of autoimmune (Type 1) diabetes mellitus shares multiple characteristics with the human disease, and studies employing this model continue to yield clinically relevant and important information. Here, we review some of the recent key findings obtained from NOD mouse investigations that have both advanced our understanding of disease pathogenesis and suggested new therapeutic targets and approaches. Areas discussed include antigen discovery, identification of genes and pathways contributing to disease susceptibility, development of strategies to image islet inflammation and the testing of therapeutics. We also review recent technical advances that, combined with an improved understanding of the NOD mouse model's limitations, should work to ensure its popularity, utility and relevance in the years ahead.

Immune cell crosstalk in type 1 diabetes

The development of type 1 diabetes involves a complex interaction between pancreatic beta-cells and cells of both the innate and adaptive immune systems. Analyses of the interactions between natural killer (NK) cells, NKT cells, different dendritic cell populations and T cells have highlighted how these different cell populations can influence the onset of autoimmunity. There is evidence that infection can have either a potentiating or inhibitory role in the development of type 1 diabetes. Interactions between pathogens and cells of the innate immune system, and how this can influence whether T cell activation or tolerance occurs, have been under close scrutiny in recent years. This Review focuses on the nature of this crosstalk between the innate and the adaptive immune responses and how pathogens influence the process.

Can infections protect against autoimmunity?

PURPOSE OF REVIEW

It has often been suggested that autoimmune diseases are initiated by certain infectious agents that mimic self-antigens or polyclonally activated autoreactive lymphocytes. An alternative, and not necessarily mutually exclusive, hypothesis that some infections might inhibit the onset of some autoimmune conditions has more recently been explored. In this review, the evidence suggesting that the current rise in the incidence of some autoimmune diseases is attributable to a decrease in the incidence of exposure to certain infections will be discussed.

RECENT FINDINGS

Studies using animal models have shown that some infectious agents or products derived from them have the potential to inhibit the onset of autoimmunity. These studies have led to the suggestion that human autoimmune or allergic diseases might be alleviated by the use of microbial products. There are some data that would support such an observation.

SUMMARY

The incidence of some autoimmune diseases has increased dramatically in recent years in the developed world. Many autoimmune diseases are governed by both genetic and environmental factors. Our immune system has coevolved with infectious agents. There have been marked changes in the exposure to certain infectious agents over the last 70 years. It has been proposed that certain infections of historical importance might inhibit the development of autoimmune disorder. This review highlights studies addressing the ways in which infectious agents might inhibit onset of autoimmunity, and how this might lead to the development of novel therapeutic approaches.

Review series on helminths, immune modulation and the hygiene hypothesis: how might infection modulate the onset of type 1 diabetes?

The development of type 1 diabetes is influenced by both genetic and environmental factors. The current rise in the incidence of diabetes is occurring more rapidly than can be accounted for by genetic change, highlighting the influence of environmental modifiers. Considerable effort has been expended to identify infectious agents that might be responsible for this rise in incidence, but no single infectious agent has been linked to this dramatic increase in type 1 diabetes. There has been increasing interest in the possibility that infections of historical importance that might have shaped our immune systems over evolutionary time may also have played a role in down-modulating some autoimmune and allergic disorders. In this review, some of the ways in which certain organisms might have influenced the onset of autoimmunity are discussed.

Infection and type 1 diabetes mellitus - a two edged sword?

Infection by various viral and bacterial pathogens has long been proposed as one of the etiologies of autoimmune diabetes. Many theories, ranging from direct cytolysis of pancreatic islet cells to immunological processes such as antigen mimicry and polyclonal lymphocyte activation, tried to explain the epidemiological correlation between infections and diabetes, supported by information from human and animal studies. However, a direct correlation and exact mechanism continue to elude investigators due to scarce and conflicting data. Interestingly, there is also data to support an opposite role for infection in the development of type 1 diabetes, as several pathogens demonstrated a protective effect from this disease. This article reviews the current data available from clinical studies and animal models, while trying to explain the different mechanisms underlying these findings.

Higher susceptibility of type 1 diabetic rats to Mycobacterium tuberculosis infection

An association between diabetes mellitus and tuberculosis has been implicated for a long time. We have previously reported that Goto Kakizaki type 2 diabetic rats are highly susceptible to Mycobacterium (M.) tuberculosis infection. As a next step, we attempted to clarify whether type 1 diabetic rats are more susceptible to M. tuberculosis than non-diabetic wild-type (WT) rats. Here, we used the Komeda diabetes-prone (KDP) rat, as a model of type 1 diabetes mellitus. The infected KDP rats developed large granulomas without central necrosis in their lungs, liver or spleen. This was consistent with a significant increase in the number of colony-forming units (cfu) of M. tuberculosis in the lungs and spleen (p < 0.01). Insulin treatment resulted in significant reduction of tubercle bacilli in the infected KDP rats (p < 0.01). Pulmonary levels of interferon-gamma, tumor necrosis factor-alpha and interleukin-1beta mRNAs were higher in the infected diabetic rats than in WT rats. Alveolar macrophages from KDP rats were not fully activated by M. tuberculosis infection because the macrophages did not secrete nitric oxide (NO) that can kill M. tuberculosis (p < 0.01), but no significant difference in phagocytosis of tubercle bacilli by alveolar macrophages was observed between KDP and WT rats. Taken together, our findings indicate that type 1 diabetic rats are more susceptible to M. tuberculosis that WT rats.

Induction of innate immune response through TLR2 and dectin 1 prevents type 1 diabetes

Studies have suggested a correlation between the decline in infectious diseases and increase in the incidence of type 1 diabetes (T1D) in developed countries. Pathogens influence the disease outcome through innate immune receptors such as TLRs. Here we report the effect of ligation of TLR2 and dectin 1 on APCs and the influence of innate immune response induced through these receptors on T1D. Exposure of APCs of NOD mice to zymosan, a fungal cell wall component that interacts with TLR2 and dectin 1, resulted in the release of significant amounts of IL-10, TGF-beta1, IL-2, and TNF-alpha. Treatment of pre- and early hyperglycemic mice with zymosan resulted in suppression of insulitis, leading to a significant delay in hyperglycemia. T cells from zymosan-treated mice showed reduced ability to induce diabetes in NOD-Scid mice compared with control T cells. Zymosan treatment induced suppression of T1D was associated with an increase in the L-selectin(high) T cell frequencies and enhanced suppressor function of CD4(+)CD25(+) T regulatory cells. Further, activation by anti-CD3-Ab induced larger amounts of TGF-beta1 and/or IL-10 production by CD4(+)CD25(+) and CD4(+)CD25(-) T cells from zymosan-treated mice. These results show that innate immune response through TLR2 and dectin 1 results in suppressor cytokine production by APCs and promotes the regulatory function of T cells. Our study demonstrates the possible involvement of signaling through innate immune receptors such as TLR2 and dectin 1 in reduced T1D incidence under the conditions of low hygiene, and the potential of targeting them for treating T1D.

Infection and autoimmunity

The development of some autoimmune diseases is increasing in the developed world faster than can be accounted for by genetic change. The development of these autoimmune diseases, such as Type 1 diabetes, is known to be influenced by both genetic and environmental factors. Environmental factors which have been considered to play a role include infectious agents such as viruses or bacteria. The search for a common initiating infection in the aetiology of Type 1 diabetes as proved thus far inconclusive. An alternative way of considering a role for infection is that infection may have historically prevented the development of autoimmune disease. In the developing world changes have occurred such that many chronic infections have been eliminated and this may have led to the emergence of autoimmune pathology. Evidence in support of this hypothesis is considered here and factors governing the development of autoimmunity compared with those which might have influenced the development of childhood leukaemia.

Dietary gluten reduces the number of intestinal regulatory T cells in mice

It is well established that gluten-free diet reduces the incidence of type 1 diabetes mellitus (T1D) in non-obese diabetic (NOD) mice, though the mechanism is not known. However, regulatory T cells (Treg) are likely to play an important role. Also, it is known that dietary gluten induces an intestinal increase in the bacterium Lactococcus garvieae, but the importance of this phenomenon for T1D development is doubtful. Our hypothesis is that gluten is responsible for mediating its effect on T1D through the influence on Treg development independent of gluten-induced Lactococci. Four groups of female NOD and BALB/c mice of 3 week old were fed either a gluten-free diet or a standard diet. Lactococcus garvieae or saline water was administered per oral to one of each dietary group. Spleen and Peyer's patches were sampled from BALB/c mice for flow cytometric monitoring of IL-10 and Treg. NOD mice were diagnosed diabetic with blood glucose level >12 mmol/l. Dietary gluten significantly decreased the occurrence of Tregs by 10-15% (P < 0.05) in mice compared with those fed a standard diet. These results and the diabetes incidence were independent of the gluten-induced bacterial factor Lactococci. The prevalence of Treg was 5- to 10-fold more abundant in the Peyer's patches than in the spleen (P < 0.001). In conclusion, dietary gluten has a significant negative quantitative impact on the generation of Treg in mice, independent of gluten-induced Lactococcus garvieae, and Treg are far more abundant in Peyer's patches than in the spleen.

Immune modulation induced by tuberculosis DNA vaccine protects non-obese diabetic mice from diabetes progression

We have described previously the prophylactic and therapeutic effect of a DNA vaccine encoding the Mycobacterium leprae 65 kDa heat shock protein (DNA-HSP65) in experimental murine tuberculosis. However, the high homology of this protein to the corresponding mammalian 60 kDa heat shock protein (Hsp60), together with the CpG motifs in the plasmid vector, could trigger or exacerbate the development of autoimmune diseases. The non-obese diabetic (NOD) mouse develops insulin-dependent diabetes mellitus (IDDM) spontaneously as a consequence of an autoimmune process that leads to destruction of the insulin-producing beta cells of the pancreas. IDDM is characterized by increased T helper 1 (Th1) cell responses toward several autoantigens, including Hsp60, glutamic acid decarboxylase and insulin. In the present study, we evaluated the potential of DNA-HSP65 injection to modulate diabetes in NOD mice. Our results show that DNA-HSP65 or DNA empty vector had no diabetogenic effect and actually protected NOD mice against the development of severe diabetes. However, this effect was more pronounced in DNA-HSP65-injected mice. The protective effect of DNA-HSP65 injection was associated with a clear shift in the cellular infiltration pattern in the pancreas. This change included reduction of CD4(+) and CD8(+) T cells infiltration, appearance of CD25(+) cells influx and an increased staining for interleukin (IL)-10 in the islets. These results show that DNA-HSP65 can protect NOD mice against diabetes and can therefore be considered in the development of new immunotherapeutic strategies.

Ectopic PDX-1 expression in liver ameliorates type 1 diabetes

Type 1 diabetes mellitus (T1DM) results from a specific autoimmune mediated destruction of the pancreatic beta-cells. PDX-1 induced developmentally redirected liver cells were suggested to restore the ablated pancreatic function in chemically induced diabetes. However, developmentally redirected liver cells, may have acquired along with the desired beta-cell characteristics and functions, also undesired sensitivity to autoimmune attack and therefore may be inefficient in ameliorating T1DM. This study analyzes whether subjects with beta-cell autoimmunity could benefit from Ad-CMV-PDX-1 gene therapy. Using the model of cyclophosphamide-accelerated diabetes in non-obese diabetic (CAD-NOD) mice, we report that recombinant adenovirus mediated PDX-1 gene therapy, ameliorates hyperglycemia in CAD-NOD mice. Our data demonstrate that 43% of the overtly diabetic CAD-NOD mice treated with Ad-CMV-PDX-1 became normoglycemic and maintained a stable body weight. Ectopic PDX-1 expression induced pancreatic gene expression and insulin production in the mice livers. The amelioration of hyperglycemia, in PDX-1 treated diabetic mice was associated with an immune modulation manifested by Th1 to Th2 shift in the autoimmune T-cell response to antigens associated with NOD diabetes. Thus, liver-to-pancreas transdifferentiation ameliorates T1DM in a process which is associated with a concomitant modulation of the autoimmune attack. Our findings suggest a beneficial therapeutic effect of the PDX-1 gene therapy for treating autoimmune type 1 diabetes mellitus (T1DM).

Parasitic worms and inflammatory diseases

The debate on whether infection precipitates or prevents autoimmunity remains a contentious one. Recently the suggestion that some unknown microbe can be at the origin of some chronic inflammatory diseases has been countered by accumulating evidence that decreasing infection rates might have an important role to play in the rising prevalence of autoimmune disorders. The 'Hygiene Hypothesis' was initially postulated to explain the inverse correlation between the incidence of infections and the rise of allergic diseases, particularly in the developed world. Latterly, the Hygiene Hypothesis has been extended to also incorporate autoimmune diseases in general. Amongst the various infectious agents, a particular emphasis has been put on the interaction between parasitic worms and humans. Worm parasites have co-evolved with the mammalian immune system for many millions of years and during this time, they have developed extremely effective strategies to modulate and evade host defences and so maintain their evolutionary fitness. It is therefore reasonable to conclude that the human immune system has been shaped by its relationship with parasitic worms and this may be a necessary requirement for maintaining our immunological health. Fully understanding this relationship may lead to novel and effective treatments for a host of deleterious inflammatory reactions.

Transforming growth factor-beta and T-cell-mediated immunoregulation in the control of autoimmune diabetes

It is now well-established that CD4+ regulatory T cells are instrumental in controlling immune responses both to self-antigens and to non-self-antigens. However, the precise modalities involved in their differentiation and survival, their mode of action and their antigen specificity are only partially understood. We have been particularly interested in the study of regulatory T cells controlling autoimmune insulin-dependent diabetes. Here, we provide evidence to support the phenotypic and functional diversity of regulatory T cells mediating transferable 'active' or 'dominant' peripheral tolerance in the non-obese diabetic mouse model (NOD). They include natural and adaptive regulatory T cells that are operational both in unmanipulated NOD mice and in animals undergoing treatments aimed at inducing/restoring tolerance to self-beta-cell antigens. At least in our hands, the differential cytokine-dependency appears as a major distinctive feature of regulatory T cells subsets. Among immunoregulatory cytokines, transforming growth factor-beta(TGF-beta) appeared to play a key role. Herein we discuss these results and the working hypothesis they evoke in the context of the present literature, where the role of TGF-beta-dependent T-cell-mediated immunoregulation is still debated.

Diabetes preventive gluten-free diet decreases the number of caecal bacteria in non-obese diabetic mice

BACKGROUND

A gluten-free diet reduces the incidence of diabetes mellitus in non-obese diabetic (NOD) mice, but the mechanism is not known. The aim of this study was to examine the possible influence of the diet on the caecal bacterial flora, which may affect the intestinal physiology and mediate disease prevention.

METHODS

Two groups of NOD mice from the age of 3 weeks were fed either a gluten-free diet or a standard diet. Each diabetic mouse, when diagnosed, along with a non-diabetic mouse from the same diet group and two non-diabetic mice from the alternate diet group were euthanized and sampled for classical bacteriological examination.

RESULTS

Nine out of 19 (47%) standard-fed mice and 1 out of 19 (5%) gluten-free-fed mice developed diabetes (p < 0.01). Mice on the gluten-free diet had significantly fewer aerobically (p < 0.01) and microaerophilically (p < 0.001) cultivated bacteria in their intestines than standard-fed mice. Non-diabetic mice also had significantly fewer microa erophilic and anaerobic bacteria than diabetic mice (p < 0.05). These differences were primarily due to a difference in the Gram-positive flora.

CONCLUSIONS

The gluten-free diet compared to the standard diet both qualitatively and quantitatively substantially altered the composition of the caecal bacterial flora in NOD mice. Although Gram-positive bacteria might influence the beta cells through certain digestive products, it is more likely to assume that any effect on diabetes incidence is immunological.

Immunomodulation and protection induced by DNA-hsp65 vaccination in an animal model of arthritis

We described a prophylactic and therapeutic effect of a DNA vaccine encoding the Mycobacterium leprae 65-kDa heat shock protein (DNA-hsp65) in experimental murine tuberculosis. However, high homology of the vaccine to the corresponding mammalian hsp60, together with the CpG motifs in the plasmidial vector, could trigger or exacerbate an autoimmune disease. In the present study, we evaluate the potential of DNA-hsp65 vaccination to induce or modulate arthritis in mice genetically selected for acute inflammatory reaction (AIR), either maximal (AIRmax) or minimal (AIRmin). Mice immunized with DNA-hsp65 or injected with the corresponding DNA vector (DNAv) developed no arthritis, whereas pristane injection resulted in arthritis in 62% of AIRmax mice and 7.3% of AIRmin mice. Administered after pristane, DNA-hsp65 downregulated arthritis induction in AIRmax animals. Levels of interleukin (IL)-12 were significantly lower in mice receiving pristane plus DNA-hsp65 or DNAv than in mice receiving pristane alone. However, when mice previously injected with pristane were inoculated with DNA-hsp65 or DNAv, the protective effect was significantly correlated with lower IL-6 and IL-12 levels and higher IL-10 levels. Our results strongly suggest that DNA-hsp65 has no arthritogenic potential and is actually protective against experimentally induced arthritis in mice.

Transforming growth factor-beta and natural killer T-cells are involved in the protective effect of a bacterial extract on type 1 diabetes

The onset of type 1 diabetes in NOD mice is delayed by oral administration of a bacterial extract (OM-85) and can be completely prevented by its intraperitoneal administration. Optimal prevention is observed when starting treatment at 3 or 6 weeks of age, and some effect is still observed with treatment at 10 weeks of age. Using genetically deficient mice and cytokine-neutralizing monoclonal antibodies, we demonstrate here that the therapeutic effect does not involve T-helper type 2 cytokines (interleukin [IL]-4 and -10) but is tightly dependent on transforming growth factor (TGF)-beta. Natural killer T-cells also participate in the therapeutic effect because CD1d(-/-) NOD mice are partially resistant to the protective effect of OM-85. The question remains of the specificity of the protective effect of OM-85, which may include proinflammatory components. It will thus be important to further characterize the molecular components that afford protection from type 1 diabetes. Lipopolysaccharide is excluded, but other Toll-like receptor (TLR) agonists could be involved because OM-85 stimulated dendritic cells and induced TGF-beta production by splenocytes in a TLR-2-, TLR-4-, and MyD88-dependent fashion.

Heat shock proteins in autoimmune diseases

Heat shock proteins (hsp's) are among the most conserved proteins in evolution. They have been identified as important pathogen-related antigens as well as autoantigens suitable for construction of novel vaccines. The high evolutionary homology of hsp's has raised the question about the safety of such vaccines. Experimental and clinical observations have confirmed that hsp proteins are involved in the regulation of some autoimmune disease such as autoimmune arthritis, type 1 diabetes mellitus, atherosclerosis, multiple sclerosis, and other autoimmune reactions. It has been shown in experimental animals that some hsp proteins (especially hsp60, hsp70, and hsp10) can either induce or prevent autoimmune reactions depending on the circumstances. This article discusses the involvement of hsp proteins in the etiology of autoimmune diseases and it presents promising experimental data on the effects of immunization with hsp proteins in the prevention and therapy of autoimmune diseases.

Thymic commitment of regulatory T cells is a pathway of TCR-dependent selection that isolates repertoires undergoing positive or negative selection

The seminal work of Le Douarin and colleagues (Ohki et al. 1987; Ohki et al. 1988; Salaun et al. 1990; Coutinho et al. 1993) first demonstrated that peripheral tissue-specific tolerance is centrally established in the thymus, by epithelial stromal cells (TEC). Subsequent experiments have shown that TEC-tolerance is dominant and mediated by CD4 regulatory T cells (Treg) that are generated intrathymically by recognition of antigens expressed on TECs (Modigliani et al. 1995; Modigliani et al. 1996a). From these and other observations, in 1996 Modigliani and colleagues derived a general model for the establishment and maintenance of natural tolerance (MM96) (Modigliani et al. 1996b), with two central propositions: (1) T cell receptor (TCR)-dependent sorting of emergent repertoires generates TEC-specific Treg displaying the highest TCR self-affinities below deletion thresholds, thus isolating repertoires undergoing positive and negative selection; (2) Treg are intrathymically committed (and activated) for a unique differentiative pathway with regulatory effector functions. The model explained the embryonic/perinatal time window of natural tolerance acquisition, by developmental programs determining (1) TCR multireactivity, (2) the cellular composition in the thymic stroma (relative abundance of epithelial vs hemopoietic cells), and (3) the dynamics of peripheral lymphocyte pools, built by accumulation of recent thymic emigrants (RTE) that remain recruitable to regulatory functions. We discuss here the MM96 in the light of recent results demonstrating the promiscuous expression of tissue-specific antigens by medullary TECs (Derbinski et al. 2001; Anderson et al. 2002; Gotter et al. 2004) and indicating that Treg represent a unique differentiative pathway (Fontenot et al. 2003; Hori et al. 2003; Khattri et al. 2003), which is adopted by CD4 T cells with high avidity for TEC-antigens (Bensinger et al. 2001; Jordan et al. 2001; Apostolou et al. 2002). In the likelihood that autoimmune diseases (AID) result from Treg deficits, some of which might have a thymic origin, we also speculate on therapeutic strategies aiming at selectively stimulating their de novo production or peripheral function, within recent findings on Treg responses to inflammation (Caramalho et al. 2003; Lopes-Carvalho et al., submitted, Caramalho et al., submitted). In short, the MM96 argued that natural tolerance is dominant, established and maintained by the activity of Treg, which are selected upon high-affinity recognition of self-ligands on TECs, and committed intrathymically to a unique differentiative pathway geared to anti-inflammatory and antiproliferative effector functions. By postulating the intrathymic deletion of self-reactivities on hemopoietic stromal cells (THC), together with the inability of peripheral resident lymphocytes to engage in the regulatory pathway, the MM96 simultaneously explained the maintenance of responsiveness to non-self in a context of suppression mediating dominant self-tolerance. The major difficulty of the MM96 is related to the apparent tissue specificity of Treg repertoires generated intrathymically. This difficulty has now been principally solved by the work of Hanahan, Kyewski and others (Jolicoeur et al. 1994; Derbinski et al. 2001; Anderson et al. 2002; Gotter et al. 2004), demonstrating the selective expression of a variety of tissue-specific antigens by TECs, in topological patterns that are compatible with the MM96, but difficult to conciliate with recessive tolerance models (Kappler et al. 1987; Kisielow et al. 1988). While the developmentally regulated multireactivity of TCR repertoires (Gavin and Bevan 1995), as well as the peripheral recruitment of Treg among RTE (Modigliani et al. 1996a) might add to this process, it would seem that the establishment of tissue-specific tolerance essentially stems from the "promiscuous expression of tissue antigens" by TEC. The findings of AID resulting from natural mutations (reviewed in Pitkanen and Peterson 2003) or the targeted inactivation (Anderson et al. 2002; Ramsey et al. 2002) of the AIRE transcription factor that regulates promiscuous gene expression on TECs support this conclusion. The observations on the correlation of natural or forced expression of the Foxp3 transcription factor in CD4 T cells with Treg phenotype and function (Fontenot et al. 2003; Hori et al. 2003; Khattri et al. 2003) provided support for the MM96 contention that Treg represent a unique differentiative pathway that is naturally established inside the thymus. Furthermore, Caton and colleagues (Jordan et al. 2001), as well as several other groups (Bensinger et al. 2001; Apostolou et al. 2002), have provided direct evidence for our postulate that Treg are selected among differentiating CD4 T cells with high affinity for ligands expressed on TECs (Modigliani et al. 1996b). Finally, the demonstration by Caramalho et al. that Treg express innate immunity receptors (Caramalho et al. 2003) and respond to pro-inflammatory signals and products of inflammation (Caramalho et al., submitted) brought about a new understanding on the peripheral regulation of Treg function. Together with the observation that Treg also respond to ongoing activities of "naïve/effector" T cells--possibly through the IL-2 produced in these conditions--these findings explain the participation of Treg in all immune responses (Onizuka et al. 1999; Shimizu et al. 1999; Annacker et al. 2001; Curotto de Lafaille et al. 2001; Almeida et al. 2002; Shevach 2002; Bach and Francois Bach 2003; Wood and Sakaguchi 2003; Mittrucker and Kaufmann 2004; Sakaguchi 2004), beyond their fundamental role in ensuring self-tolerance (e.g., Modigliani et al. 1996a; Shevach 2000; Hori et al. 2003; Sakaguchi 2004; Thompson and Powrie 2004). Thus, anti-inflammatory and anti-proliferative Treg are amplified by signals that promote or mediate inflammation and proliferation, accounting for the quality control of responses (Coutinho et al. 2001). In turn, such natural regulation of Treg by immune responses to non-self may well explain the alarming epidemiology of allergic and AID in wealthy societies (Wills-Karp et al. 2001; Bach 2002; Yazdanbakhsh et al. 2002), where a variety of childhood infections have become rare or absent. Thus, it is plausible that Treg were evolutionarily set by a given density of infectious agents in the environment. With hindsight, it is not too surprising that natural Treg performance falls once hygiene, vaccination, and antibiotics suddenly (i.e., 100 years) plunged infectious density to below some critical physiological threshold. As the immune system is not adapted to modern clean conditions of postnatal development, clinical immunologists must now deal with frequent Treg deficiencies (allergies and AID) for which they have no curative or rational treatments. It is essential, therefore, that basic immunologists concentrate on strategies to selectively stimulate the production, survival, and activity of this set of lymphocytes that is instrumental in preventing immune pathology. We have argued that the culprit of this inability of basic research to solve major clinical problems has been the self-righteousness of recessive tolerance champions, from Ehrlich to some of our contemporaries. It is ironical, however, that none of us--including the heretic opponents of horror autotoxicus--had understood that self-tolerance, or its robustness at least, is in part determined by the frequency and intensity of the responses to non-self. In the evolution of ideas on immunological tolerance, the time might be ripe for some kinds of synthesis. First, conventional theory reduced self-tolerance to negative selection and microbial defense to positive selection, while the MM96 solution was the precise opposite: positive selection of autoreactivities for self-tolerance (Treg) and negative selection (of Treg) for ridding responses. In contrast, it would now appear that positive and negative selection of autoreactive T cells are both necessary to establish either self-tolerance or competence to eliminate microbes, two processes that actually reinforce each other in the maintenance of self-integrity. Second, V-region recognition has generally been held responsible for specific discrimination between what should be either tolerated or eliminated from the organism. In contrast again, it would now seem that both processes of self-tolerance and microbial defense (self/non-self discrimination) also operate on the basis of evolutionarily ancient, germ-line-encoded innate, nonspecific receptors (Medzhitov and Janeway 2000) capable of a coarse level of self/non-self discrimination (Coutinho 1975). It could thus be interesting to revisit notions of cooperativity between V-regions and such mitogen receptors, both in single cell functions (Coutinho et al. 1974) and in the system's evolution (Coutinho 1975, 1980) as well. After all, major transitions in evolution were cooperative (Maynard-Smith and Szathmary 1995).

A worm's eye view of the immune system: consequences for evolution of human autoimmune disease

Humans and the many parasites that we can host have co-evolved over millions of years. This has been compared to an arms race in which the immune armoury of the human has evolved to deal with potential pathogens and the pathogen has evolved strategies to evade, and in some cases use, the immune system of the human host. Recently, there have been marked changes in the exposure of individuals in the developed world to both microorganisms and metazoan parasites, so the immune stimuli such organisms provide no longer have a role in our lives. As we discuss here, this is a marked perturbation, and the absence of the associated immunomodulation might have led to the increased emergence of autoimmune diseases.

Pulmonary tuberculosis in spontaneously diabetic goto kakizaki rats

As a clinical association is thought to exist between diabetes and tuberculosis, this study was set up to examine whether GK/Jcl diabetic rats are more susceptible to Mycobacterium tuberculosis infection than non-diabetic rats. GK/Jcl diabetic rats were infected aerially with M. tuberculosis and their capacity to control mycobacterial growth, granuloma formation, cytokine secretion by alveolar macrophages and nitric oxide (NO) production was examined. The rats developed large granulomas but not necrotic lesions in their lungs, liver or spleen. This is consistent with a significant increase in number of colony-forming units of M. tuberculosis in the lungs (p<0.01). Expression levels of interferon-gamma, tumor necrosis factor (TNF)-alpha and interleukin (IL)-12 mRNA were lower in GK/Jcl diabetic rats than those in control Wistar rats. Alveolar macrophages from GK/Jcl rats secreted less TNF-alpha and IL-12, and produced less NO compared with those from Wistar rats. No significant difference was observed between phagocytosis of tubercle bacilli by alveolar macrophages from GK/Jcl or Wistar rats. These data show that there is a close association between experimental tuberculosis and diabetes in animals, and that alveolar macrophages from GK/Jcl diabetic rats are not fully activated by M. tuberculosis infection.

TLR activation synergizes with Kilham rat virus infection to induce diabetes in BBDR rats

Virus infection is hypothesized to be an important environmental "trigger" of type 1 diabetes in humans. We used the BBDR rat model to investigate the relationship between viral infection and autoimmune diabetes. BBDR rats are diabetes-free in viral Ab-free housing, but the disease develops in approximately 30% of BBDR rats infected with Kilham rat virus (KRV) through a process that does not involve infection of pancreatic beta cells. Pretreatment with polyinosinic-polycytidylic (poly(I:C)), a ligand of TLR3, acts synergistically to induce diabetes in 100% of KRV-infected rats. The mechanisms by which KRV induces diabetes and TLR3 ligation facilitates this process are not clear. In this study, we demonstrate that activation of the innate immune system plays a crucial role in diabetes induction. We report that multiple TLR agonists synergize with KRV infection to induce diabetes in BBDR rats, as do heat-killed Escherichia coli or Staphylococcus aureus (natural TLR agonists). KRV infection increases serum IL-12 p40 in a strain-specific manner, and increases IL-12 p40, IFN-gamma-inducible protein-10, and IFN-gamma mRNA transcript levels, particularly in the pancreatic lymph nodes of BBDR rats. Infection with vaccinia virus or H-1 parvovirus induced less stimulation of the innate immune system and failed to induce diabetes in BBDR rats. Our results suggest that the degree to which the innate immune system is activated by TLRs is important for expression of virus-induced diabetes in genetically susceptible hosts.

Graves' hyperthyroidism and the hygiene hypothesis in a mouse model

Graves' hyperthyroidism is an organ-specific autoimmune disease mediated by stimulatory autoantibodies against the TSH receptor (TSHR; thyroid-stimulating antibodies), causing thyroid hyperplasia and hyperthyroidism. Development of this ailment is well known to be under polygenic and environmental control. For example, we recently demonstrated that parasite helminth Schistosoma mansoni infection suppressed a T helper cell type 1 (Th1)-type anti-TSHR immune response and prevented disease development in our mouse model of Graves' disease using adenovirus coding for the TSHR. In the present study we examined the outcome of infection with Mycobacterium bovis bacillus Calmette-Guerin (BCG), a Th1-promoting infectious pathogen, on Graves' disease. Our results show that prior infection with M. bovis BCG differentiates the TSHR-specific immune response toward a Th1 phenotype, as demonstrated by enhanced secretion of a Th1 cytokine interferon-gamma and impaired production of a Th2 cytokine IL-10 from splenocytes stimulated in vitro with TSHR antigen. M. bovis BCG also significantly suppressed disease induction. These data together with our recent report that coinjection of adenovirus expressing the Th1 cytokine IL-12 induced a Th1-polarized, TSHR-specific immune response without affecting disease development support the hygiene hypothesis, rather than Th1-mediated disease suppression. Thus, some infectious pathogens may influence the development of Graves' disease regardless of their ability to modify the Th1/Th2 balance.

Functional immunomics: microarray analysis of IgG autoantibody repertoires predicts the future response of mice to induced diabetes

One's present repertoire of antibodies encodes the history of one's past immunological experience. Can the present autoantibody repertoire be consulted to predict resistance or susceptibility to the future development of an autoimmune disease? Here, we developed an antigen microarray chip and used bioinformatic analysis to study a model of type 1 diabetes developing in nonobese diabetic male mice in which the disease was accelerated and synchronized by exposing the mice to cyclophosphamide at 4 weeks of age. We obtained sera from 19 individual mice, treated the mice to induce cyclophosphamide-accelerated diabetes (CAD), and found, as expected, that 9 mice became severely diabetic, whereas 10 mice permanently resisted diabetes. We again obtained serum from each mouse after CAD induction. We then analyzed, by using rank-order and superparamagnetic clustering, the patterns of antibodies in individual mice to 266 different antigens spotted on the chip. A selected panel of 27 different antigens (10% of the array) revealed a pattern of IgG antibody reactivity in the pre-CAD sera that discriminated between the mice resistant or susceptible to CAD with 100% sensitivity and 82% specificity (P = 0.017). Surprisingly, the set of IgG antibodies that was informative before CAD induction did not separate the resistant and susceptible groups after the onset of CAD; new antigens became critical for post-CAD repertoire discrimination. Thus, at least for a model disease, present antibody repertoires can predict future disease, predictive and diagnostic repertoires can differ, and decisive information about immune system behavior can be mined by bioinformatic technology. Repertoires matter.

Vaccinations May Induce Diabetes-Related Autoantibodies in One-Year-Old Children

Vaccinations have been discussed as one among many environmental candidates contributing to the immune process that later may lead to type 1 diabetes. ABIS (All Babies in Southeast Sweden) is a prospective cohort study following a nonselected birth cohort of general population. In a randomly selected sample collection from 4400 children, GADA and IA-2A have been determined at the age of 1 year. The information on vaccinations was collected from questionnaires answered by the parents and was related to beta cell autoantibodies. When studying the induction of autoantibodies using the autoantibody level of 90th percentile as cutoff level, hemophilus influenza B (HIB) vaccination appeared to be a risk factor for IA-2A [OR 5.9 (CI 1.4-24.4; p = 0.01)] and for GADA [OR 3.4 (CI 1.1-10.8; p = 0.04)] in logistic regression analyses. Furthermore, the titers of IA-2A were significantly higher (p < 0.01 in Mann-Whitney test) in those children who had got HIB vaccination. When 99th percentile was used as cutoff to identify the children at risk of type 1 diabetes, BCG vaccination was associated with increased prevalence of IA-2A (p < 0.01). We conclude that HIB vaccination may have an unspecific stimulatory polyclonal effect increasing the production of GADA and IA-2A. This might be of importance under circumstances when the beta cell-related immune response is activated by other mechanisms.

DNA vaccination with heat shock protein 60 inhibits cyclophosphamide-accelerated diabetes

Nonobese diabetic (NOD) mice spontaneously develop diabetes as a consequence of an autoimmune process that can be inhibited by immunotherapy with the 60-kDa heat shock protein (hsp60), with its mycobacterial counterpart 65-kDa (hsp65), or with other Ags such as insulin and glutamic acid decarboxylase (GAD). Microbial infection and innate signaling via LPS or CpG motifs can also inhibit the spontaneous diabetogenic process. In addition to the spontaneous disease, however, NOD mice can develop a more robust cyclophosphamide-accelerated diabetes (CAD). In this work, we studied the effect on CAD of DNA vaccination with constructs encoding the Ags human hsp60 (phsp60) or mycobacterial hsp65 (phsp65). Vaccination with phsp60 protected NOD mice from CAD. In contrast, vaccination with phsp65, with an empty vector, or with a CpG-positive oligonucleotide was not effective, suggesting that the efficacy of the phsp60 construct might be based on regulatory hsp60 epitopes not shared with its mycobacterial counterpart, hsp65. Vaccination with phsp60 modulated the T cell responses to hsp60 and also to the GAD and insulin autoantigens; T cell proliferative responses were significantly reduced, and the pattern of cytokine secretion to hsp60, GAD, and insulin showed an increase in IL-10 and IL-5 secretion and a decrease in IFN-gamma secretion, compatible with a shift from a Th1-like toward a Th2-like autoimmune response. Our results extend the role of specific hsp60 immunomodulation in the control of beta cell autoimmunity and demonstrate that immunoregulatory networks activated by specific phsp60 vaccination can spread to other Ags targeted during the progression of diabetes, like insulin and GAD.

Elimination of maternally transmitted autoantibodies prevents diabetes in nonobese diabetic mice

The influence of maternally transmitted immunoglobulins on the development of autoimmune diabetes mellitus in genetically susceptible human progeny remains unknown. Given the presence of islet beta cell-reactive autoantibodies in prediabetic nonobese diabetic (NOD) mice, we abrogated the maternal transmission of such antibodies in order to assess their influence on the susceptibility of progeny to diabetes. First, we used B cell-deficient NOD mothers to eliminate the transmission of maternal immunoglobulins. In a complementary approach, we used immunoglobulin transgenic NOD mothers to exclude autoreactive specificities from the maternal B-cell repertoire. Finally, we implanted NOD embryos in pseudopregnant mothers of a non-autoimmune strain. The NOD progeny in all three groups were protected from spontaneous diabetes. These findings demonstrate that the maternal transmission of antibodies is a critical environmental parameter influencing the ontogeny of T cell-mediated destruction of islet beta cells in NOD mice. It will be important to definitively determine whether the transmission of maternal autoantibodies in humans affects diabetes progression in susceptible offspring.

Immunotherapy of type 1 diabetes: lessons for other autoimmune diseases

The nonobese diabetic (NOD) mouse is a well-recognised animal model of spontaneous autoimmune insulin-dependent diabetes mellitus. The disease is T-cell mediated, involving both CD4 and CD8 cells. Its progress is controlled by a variety of regulatory T cells. An unprecedented number of immunological treatments have been assessed in this mouse strain. This chapter systematically reviews most of these therapeutic manoeuvres, discussing them in the context of their significance with regard to the underlying mechanisms and the potential clinical applications. The contrast between the surprisingly high rate of success found for a multitude of treatments (more than 160) administered early in the natural history of the disease and the few treatments active at a late stage is discussed in depth. Most of the concepts and strategies derived from this model apply to other autoimmune diseases, for which no such diversified data are available.

Autoantibody patterns in diabetes-prone NOD mice and in standard C57BL/6 mice

Autoantibodies are commonly found in healthy individuals and strains of mice that are not prone to autoimmunity. The present study was undertaken to identify self antigens recognized by serum autoantibodies from unimmunized mice of two strains: NOD mice prone to spontaneously develop autoimmune diabetes and C57BL/6 mice known to be relatively resistant to autoimmune disease. IgM and IgG autoantibodies detected in the sera of NOD and C57BL/6 mice manifested different patterns of reactivity. The IgM autoantibodies from C57BL/6 serum reacted with more self antigens and showed higher OD values than the IgM autoantibodies from NOD mice. In contrast, the IgG autoantibodies from NOD serum reacted with more antigens and displayed higher OD readings than did IgG autoantibodies from C57BL/6 mice. Among the antigens recognized by the autoantibodies, particularly of the IgG class, were self antigens known to induce experimental autoimmune diseases in NOD and C57BL/6 mice. In addition, IgG autoantibodies from NOD mice reacted with self antigens reported to mark the spontaneous autoimmune diabetes that characterizes this strain of mice. These results suggest that naturally occurring IgG autoantibodies reflect susceptibility to induction of specific autoimmune diseases. In addition, the results suggest that IgM autoantibodies may by associated with mechanisms that might prevent autoimmune disease.

NOD mice are resistant to depletion of thymic cells caused by acute stress or infection

NOD mice spontaneously develop autoimmune diabetes; disease onset in females of our colony of NOD mice usually takes place around the 4th month of age. Diabetes of NOD mice can be modulated by different stress protocols, even though these animals were shown to be resistant to the effects of glucocorticoids on their lymphocytes. We have recently found that the early host inflammatory response to mycobacteria can be strongly modified by stress, the autoimmunity-prone NOD and NZB/W mice being particularly affected. These mice show reduced numbers of granulocytes in the inflammatory cavity after exposure to stress. Mycobacterium avium is an opportunistic agent that is responsible for disseminated infections seen in AIDS patients. Here, we investigated whether the early immune response to M. avium was altered by stress in NOD mice and we compared the stress response of these mice with a non-autoimmune strain, BALB/c mice. The effects of stress on infected BALB/c mice, which like AIDS patients are susceptible to M. avium infection, offers experimental evidence that M. avium infection, if coupled with stress of the host, may accelerate loss of T helper cells. In contrast, in NOD mice, stress or infection significantly increased the number of cells of the thymuses of the animals. Data obtained with NOD mice support the previously reported resistance of NOD mice lymphocytes to glucocorticoids and suggest that there are two distinct signalling pathways involved in the response of NOD lymphocytes to these stress hormones: one leading to apoptosis and the other mediating glucocorticoid inhibition of activation-induced cell death.

A role for CD45RBlow CD38+ T cells and costimulatory pathways of T-cell activation in protection of non-obese diabetic (NOD) mice from diabetes

Non-obese diabetic (NOD) mice spontaneously develop autoimmune insulin-dependent diabetes mellitus (IDDM). Infection of the animals with mycobacteria, or immunization with mycobacteria-containing adjuvant, results in permanent protection of NOD mice from diabetes and we have recently reported that the phenomenon is associated with increased numbers of interferon-gamma-producing T cells, possessing increased cytotoxic activity, and also with augmented numbers of activated immunoglobulin M-positive (IgM+) B cells. Here, we have investigated whether protection of NOD mice from IDDM was associated with changes on costimulatory pathways of T and B cells, namely CD28/CTLA-4-B7 and CD40-CD40 ligand (CD40L) and we also further characterized protective T helper (Th) cells with regards to the expression of the differentiation markers CD45RB and CD38. We report that Th cells involved in diabetes vaccination of NOD mice by mycobacterial infection seem to belong to CD45RBlo CD38+ phenotype. The protective effect of Mycobacterium avium infection is also associated with increased CD40L and CTLA-4- expressing Th cells and with the generation of a CD40- IgG+ B cells. Our data are consistent with induction by mycobacterial infection of regulatory CD45RBlo CD38+ Th cells with the ability to trigger deletion or anergy of peripheral self-reactive lymphocytes, with shutting down of IgG+ B-cell response. They also implicate a role for IgG+ B cells in the autoimmune aggression of the endocrine pancreas of NOD mice.