Inhibition of diabetes in NOD mice by idiotypic induction of SLE

Dysregulation of T lymphocyte proliferative responses in autoimmunity

T cells are critically dependent on cellular proliferation in order to carry out their effector functions. Autoimmune strains are commonly thought to have uncontrolled T cell proliferation; however, in the murine model of autoimmune diabetes, hypo-proliferation of T cells leading to defective AICD was previously uncovered. We now determine whether lupus prone murine strains are similarly hyporesponsive. Upon extensive characterization of T lymphocyte activation, we have observed a common feature of CD4 T cell activation shared among three autoimmune strains-NOD, MRL, and NZBxNZW F1s. When stimulated with a polyclonal mitogen, CD4 T cells demonstrate arrested cell division and diminished dose responsiveness as compared to the non-autoimmune strain C57BL/6, a phenotype we further traced to a reliance on B cell mediated costimulation, which underscores the success of B cell directed immune therapies in preventing T cell mediated tissue injury. In turn, the diminished proliferative capacity of these CD4 T cells lead to a decreased, but activation appropriate, susceptibility to activation induced cell death. A similar decrement in stimulation response was observed in the CD8 compartment of NOD mice; NOD CD8 T cells were distinguished from lupus prone strains by a diminished dose-responsiveness to anti-CD3 mediated stimulation. This distinction may explain the differential pathogenetic pathways activated in diabetes and lupus prone murine strains.

Epigallocatechin gallate delays the onset of type 1 diabetes in spontaneous non-obese diabetic mice

Type 1 diabetes (T1D) results from the autoimmune-mediated destruction of pancreatic β-cells, leading to deficiency of insulin production. Successful islet transplantation can normalise hyperglycaemia in T1D patients; however, the limited availability of the islets, loss of islet cell mass through apoptosis after islet isolation and potential autoimmune destruction of the transplanted islets prevent the widespread use of this procedure. Therefore, the search for novel and cost-effective agents that can prevent or treat T1D is extremely important to decrease the burden of morbidity from this disease. In the present study, we discovered that ( - )-epigallocatechin gallate (EGCG, 0·05 % in drinking-water), the primary polyphenolic component in green tea, effectively delayed the onset of T1D in non-obese diabetic (NOD) mice. At 32 weeks of age, eight (66·7 %) out of twelve mice in the control group developed diabetes, whereas only three (25 %) out of twelve mice in the EGCG-treated group became diabetic (P < 0·05). Consistently, mice supplemented with EGCG had significantly higher plasma insulin levels and survival rate but lower glycosylated Hb concentrations compared with the control animals. EGCG had no significant effects on food or water intake and body weight in mice, suggesting that the glucose-lowering effect was not due to an alteration in these parameters. While EGCG did not modulate insulitis, it elevated the circulating anti-inflammatory cytokine IL-10 level in NOD mice. These findings demonstrate that EGCG may be a novel, plant-derived compound capable of reducing the risk of T1D.

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.

Effect of standard nicotinamide in the prevention of type 1 diabetes in first degree relatives of persons with type 1 diabetes

BACKGROUND

Nicotinamide has been used with success to prevent type 1 diabetes in animal models and humans. This vitamin B3 derivative has attracting effects on beta-cell protection and regeneration.

AIM/HYPOTHESIS

To evaluate the effect of standard nicotinamide administration on type 1 diabetes prevention in first degree relatives of persons with type 1 diabetes as well as on the concentrations of islet-cell-related autoantibodies, insulin secretion and peripheral sensitivity.

SUBJECTS AND METHODS

A randomized double-blind placebo controlled intervention trial was conducted in 40 first degree relatives of type 1 diabetic patients. Persistence of ICA ( >or= 10 JDF units) was among inclusion criteria. Participants were randomly allocated oral standard nicotinamide (1.2 g/m2) or placebo for 5 years. Groups were also stratified by age. Islet associated antibodies, fasting blood glucose, fasting plasma insulin concentrations, OGTT, IVGTT and HLA-DR genotyping were performed in all participants. The main criterion to stop treatment was type 1 diabetes development as defined by WHO.

RESULTS

Type 1 diabetes development frequencies were similar between the treatment groups. ICA frequencies at the end of the study, first phase insulin release, and insulin sensitivity did not differ between groups as well. None of the participants suffered from any adverse events described for nicotinamide.

CONCLUSIONS

Type 1 diabetes prevention trial using standard nicotinamide is feasible but fails to prevent or delay the disease onset at the dose we used.

NOD B-cells are insufficient to incite T-cell-mediated anti-islet autoimmunity

Although it is well established that B-cells are required for the development of diabetes in the nonobese diabetic (NOD) mouse, the nature of their role remains unknown. Herein, we investigate the hypothesis that B-cells in this autoimmune background actively disrupt the tolerant state of those T-cells with which they interact. We demonstrate that NOD B-cells express elevated levels of crucial molecules involved in antigen presentation (including CD21/35, major histocompatibility complex class II, and CD40), alterations that invite the possibility of inappropriate T-cell activation. However, when chimeric animals are generated in which all B-cells are NOD-derived, a tolerant state is maintained. These data demonstrate that although B-cells are required for the development of autoimmunity, they are not sufficient to disrupt established tolerance. Moreover, non-B-cell antigen-presenting cells may be the critical actors in the establishment of the tolerant state; this function may be absent in NOD mice as they are characterized by deficient professional antigen-presenting cell function.

The natural autoantibody repertoire and autoimmune disease

The incidence of autoimmune diseases has shown a significant increase in developed countries during the last 40 years. The cause of this increase is still unknown, and reliable methods for the detection of individuals at risk of developing autoimmune disease are not available yet. To explore new methods for the diagnosis and monitoring of autoimmune disease, we have studied the repertoire of natural autoantibodies (NA) and its relationship with autoimmune disease using large arrays of defined antigens. NA are found in healthy humans and mice, apparently in the absence of immunization with their target antigens. We used knock-out mice to demonstrate that the repertoire of NA is influenced by factors not directly related to antigenic stimulation such as endogenous levels of histamine. By studying strains of mice known to differ in their susceptibility to autoimmune disease, we could conclude that the repertoire of NA reflects the susceptibility to develop autoimmune disease. The study of the human repertoire of NA required the development of bio-informatic tools to overcome the variation introduced by individual differences in the genetic background and immune history. We found that human NA are organized in clusters that can differentiate healthy subjects from patients with type 1 diabetes mellitus, type 2 diabetes mellitus or Behçet's disease patients. The development of new tools to undertake large-scale NA analysis could also enhance our understanding of the immune system, and leave us in a better position to face the up-coming epidemics of autoimmune disorders.

Genetic heterogeneity of autoimmune disorders in the nonobese diabetic mouse

The nonobese diabetic mouse is highly susceptible not only to diabetes but to several autoimmune diseases, and one might suspect that these are controlled by a shared set of genes. However, based on various gene-segregation experiments, it seems that only a few loci are shared and that each disorder is influenced also by a unique set of genes.

Generalization of single immunological experiences by idiotypically mediated clonal connections

Clonal interactions of B cells by idiotope-specific mutual recognition of their antigen receptors with the participation of T cells were assumed to form a web of unknown density, referred to as the idiotypic network. Although these clonal connections were proposed to fulfill important internal regulatory functions, their biological significance, especially in relation to antigen-induced immune responses, remained a mystery. In view of this, we postulate that the basic function of the idiotypic internal connection between B and T cell antigen receptors is to transform antigen-induced cellular activations, by idiotypic crossreactivity, into the regulation of cell clones with different antigen specificities. This process leads not only to the suppression of major clones but also to the activation of minor ones. The latter activating property may allow the generalization of single antigenic experiences, so that the immune system in its entirety benefits in its battle against environmental microbes. Such idiotypic clonal interactions are particularly effective in early ontogeny. During a short neonatal imprinting period, maternal immunological knowledge in the form of somatically mutated, high-affinity IgG antibodies, acquired through a continuous encounter with external antigens, guides the initial ontogenetic development of the immune system and so exerts long-lasting transgenerational advantageous effects in the 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.

Bcg and autoimmunity: another two-edged sword

BCG immunotherapy for bladder carcinoma has been a long-standing treatment modality that has proved itself efficient and safe. Most of the side-effects of this treatment are minor and of short duration. There have been, nevertheless, several reports regarding more severe and long-term complications of BCG therapy-namely inflammatory arthritis, and occasionally systemic autoimmune manifestations. Here, we present four cases of patients who received intravesical instillation with BCG for bladder carcinoma and developed long-standing inflammatory arthritis. One of these patients developed Reiter's syndrome. We also refer to the possible immune mechanisms by which BCG can trigger arthritis, as well as to the link between mycobacterial infection, BCG immunotherapy and autoimmunity.

Vaccination with empty plasmid DNA or CpG oligonucleotide inhibits diabetes in nonobese diabetic mice: modulation of spontaneous 60-kDa heat shock protein autoimmunity

Nonobese diabetic (NOD) mice develop insulitis and diabetes through a process involving autoimmunity to the 60-kDa heat shock protein (HSP60). Treatment of NOD mice with HSP60 or with peptides derived from HSP60 inhibits this diabetogenic process. We now report that NOD diabetes can be inhibited by vaccination with a DNA construct encoding human HSP60, with the pcDNA3 empty vector, or with an oligonucleotide containing the CpG motif. Prevention of diabetes was associated with a decrease in the degree of insulitis and with down-regulation of spontaneous proliferative T cell responses to HSP60 and its peptide p277. Moreover, both the pcDNA3 vector and the CpG oligonucleotide induced specific Abs, primarily of the IgG2b isotype, to HSP60 and p277, and not to other islet Ags (glutamic acid decarboxylase or insulin) or to an unrelated recombinant Ag expressed in bacteria (GST). The IgG2b isotype of the specific Abs together with the decrease in T cell proliferative responses indicate a shift of the autoimmune process to a Th2 type in treated mice. These results suggest that immunostimulation by bacterial DNA motifs can modulate spontaneous HSP60 autoimmunity and inhibit NOD diabetes.