The influence of high dose intravenous immunoglobulins on immunological and metabolic pattern in newly diagnosed type I diabetic patients

Intravenous immunoglobulin (IVIg) acts directly on conventional T cells to suppress T cell receptor signaling

Intravenous immunoglobulin (IVIg) therapy is widely used to treat autoimmune and infectious disorders. Despite the clinical efficacy of IVIg therapy, its precise immunosuppressive mechanisms remain unclear. Here, we provide evidence that IVIg acts directly on T cells to suppress their activation upon T cell receptor (TCR) ligation. IVIg suppressed the proliferation of murine splenocytes upon stimulation with anti-CD3 antibody and T cell-tropic mitogens. These immunosuppressive effects of IVIg were still intact against purified T cells, and the depletion of naturally-occurring regulatory T cells (nTreg) had no effect on T cell regulatory activity. Instead, we found that IVIg negatively regulated TCR signaling; IVIg co-stimulation impaired IκB degradation, nuclear translocation of the nuclear factor of activated T cells (NFAT), and the activation of mitogen-activated protein kinase (MAPK, Erk1/2). These results suggest an additional new immunosuppressive role of IVIg, which acts directly on conventional T cells to suppress the TCR signaling pathway.

Protective role of anti-idiotypic antibodies in autoimmunity--lessons for type 1 diabetes

Circulating autoantibodies to beta cell antigens are present in the majority of patients with Type 1 diabetes. These autoantibodies can be detected before and at time of clinical diagnosis of disease. Although the role of autoantibodies in the pathogenesis of the disease is debated, their presence indicates a dysregulation of the humoral immune response. Mechanisms regulating autoantibodies in Type 1 diabetes are not well understood. In contrast, in other autoimmune diseases there is acceptance that autoantibodies are regulated not only by antigen but also by other antibodies that bind to the antigen-binding site of these autoantibodies (anti-idiotypic antibodies). The proposed purpose of this network is to maintain an equilibrium between autoantibodies and their anti-idiotypic antibodies, preventing autoimmunity, while allowing a robust response to exogenous antigen. Anti-idiotypic antibodies regulate both autoantibody binding and their levels by a) neutralizing autoantibodies, and b) inhibiting the secretion of autoantibodies. Because it has been proposed that the B lymphocytes that produce autoantibodies function as autoantigen presenting cells, inhibiting their binding to autoantigen by anti-idiotypic antibodies may prevent development of autoimmune disease. This hypothesis is supported by the presence of anti-idiotypic antibodies in healthy individuals and in patients in remission from autoimmune diseases, and by the lack of anti-idiotypic antibodies during active disease. We recently reported the presence of autoantibodies to glutamate decarboxylase in the majority of healthy individuals, where their binding to autoantigen is prevented by anti-idiotypic antibodies. These anti-idiotypic antibodies are absent at clinical diagnosis of Type 1 diabetes, revealing the presence of autoantibodies. Type 1 diabetes (T1D) is an autoimmune disease characterized by the dysfunction and destruction of insulin-producing beta cells by autoreactive T cells. Although much progress has been made towards understanding the respective roles of effector and regulatory T cells in this beta cell destruction, the development of autoantibodies to beta cell proteins is widely considered simply a by-product of the autoimmune destruction of the beta cells, rather than having an active role in the pathogenesis. This view is starting to change based on increasing recognition that autoantibodies can have defined roles in other autoimmune diseases, and the emergence of new data on their role in T1D. This exploration of the role of autoantibodies in autoimmune disease has been spurred, in part, by increasing recognition that development of autoimmune diseases is influenced by regulatory antibodies (anti-idiotypic antibodies) directed against the unique binding site of autoantibodies. This review provides an overview of the development and function of these anti-idiotypic antibodies, and present evidence supporting their role in the development of autoimmune diseases. Finally, we conclude this review with a model of the events that may cause loss of anti-idiotypic antibodies and the implications for the development of T1D.

Immunotherapeutic agents in type 1 diabetes: a systematic review and meta-analysis of randomized trials

OBJECTIVE

Although recent trial results of anti-CD3 therapy are promising, there have been conflicting results of various immunotherapeutic agents used in patients with type 1 diabetes. We conducted a systematic review and meta-analysis to determine the efficacy of nonantigen-based immunotherapeutic approaches for preservation of beta-cell function in patients with type 1 diabetes.

METHODS

We searched MEDLINE, EMBASE, Cochrane CENTRAL, reference lists, and content expert files up to September 2006. Eligible studies were randomized controlled trials (RCTs) of antiproliferative agents (methotrexate, azathioprine), monoclonal antibodies (CD3, CD4), T-cell inhibitors (cyclosporin) and other immunotherapeutic agents (photopheresis, linomide, fusidin, buffy coat, intravenous immunoglobulin, BCG, nicotinamide) in patients with newly diagnosed type 1 diabetes followed for > or = 6 months. Pairs of reviewers working independently and with adequate reliability assessed the trials' methodological quality, collected data, and conducted random-effects meta-analyses on measures of preservation of beta-cell function (e.g. C-peptide secretion, insulin independence).

RESULTS

Of the 299 potentially relevant articles identified after an initial search, 20 trials met selection criteria. Meta-analysis of 20 trials (n = 1187 patients) found a small to moderate improvement in beta-cell function with immunotherapy [vs. placebo, effect size 0.37, 95% confidence interval (CI) 0.14-0.6] but there was moderate inconsistency in results across trials (I(2) 65%, 95% CI 39-77%). Subgroup analysis suggested a greater effect of cyclosporin and antiproliferative agents on beta-cell function when used for > or = 6 months (pooled effect size 0.77 vs. -0.11, respectively; P(interaction) = 0.002).

CONCLUSIONS

Long-term immunotherapy may preserve beta-cell function in newly diagnosed patients with type 1 diabetes. Patients and clinicians must await the conduct of rigorous trials reporting on diabetes resolution, adverse events, and other patient-important outcomes.

Modulation of diabetes in NOD mice by GAD65-specific monoclonal antibodies is epitope specific and accompanied by anti-idiotypic antibodies

Type 1 diabetes is caused by the autoimmune destruction of pancreatic beta cells. Here we show that administration of a human monoclonal antibody (b96.11) specific to the 65-kDa isoform of glutamate decarboxylase (GAD65) to prediabetic non-obese diabetic (NOD) mice significantly delays the onset of autoimmune diabetes. We found this effect to be epitope-specific, as only b96.11 showed this therapeutic property, while a GAD65-specific human monoclonal control antibody (b78) derived from the same patient, but specific to a different determinant of GAD65, had no significant effect on the progression of disease. Administration of b96.11 or b78 to NOD mice was accompanied by the generation of anti-idiotypic antibodies. Importantly, the induced anti-idiotypic antibodies were specific for the immunizing antibody and blocked the binding of GAD65 by the respective antibody. These findings suggest a potential role for the internal image of the GAD65 determinant recognized by b96.11 in the anti-idiotypic antibody, supporting an immunomodulatory role for GAD65-specific autoantibodies, as originally postulated by Jerne.

Modulation of dendritic cell development by immunoglobulin G in control subjects and multiple sclerosis patients

Intravenous immunoglobulin (IVIg) preparations are reportedly effective in inhibiting the relapse of multiple sclerosis (MS), but few reports have investigated the effect of IVIg on dendritic cells (DCs), which are thought to be involved in such relapses. In the system that uses monokines to differentiate DCs from peripheral blood monocytes (Mo-DCs), we investigated the effect of immunoglobulin G (IgG) on these antigen-presenting cells. Using monocytes derived from healthy volunteers, IgG partially inhibited the expression of CD1a, a marker of immature DCs (imDCs), and CD40 and CD80, which are markers associated with T cell activation. In contrast, IgG enhanced the expression of CD83, a marker of mature DCs (mDCs). Furthermore, IgG markedly inhibited the expression of CD49d [very late activation antigen (VLA)-4 alpha4-integrin], the adhesion molecule required for mDCs to cross the blood-brain barrier. We obtained similar results on all the aforementioned cell surface molecules investigated in both healthy controls and MS patients. In addition, IgG treatment of cells from both healthy controls and MS patients inhibited the production of interleukin (IL)-12, a cytokine associated with mDC differentiation, but did not inhibit the production of IL-10. These results suggested the possibility that IgG treatment, apart from its known ability to regulate inflammation, may help to prevent relapses of MS by controlling DC maturation, consequently inhibiting invasion of immune cells into the central nervous system and affecting the cytokine profile.

Type 1 diabetes intervention trials: what have we learned? A critical review of selected intervention trials

Developing therapies to stop or slow the immune destruction of islets has been a goal of investigators in type 1 diabetes for several decades. This review of clinical interventions in patients with type 1 diabetes indicates both negative and positive outcomes with a variety of different therapeutic agents. An underlying theme of this article is that differences in study design may impact the outcome more than the therapy being tested. Thus, each of these results need to be considered in the context of important variables in study design. To date, there is no clear answer as to what study design is best to determine if an agent is effective against the diabetes disease process; however, the Immunology of Diabetes Society has recently developed guidelines for the conduct of these trials to facilitate comparisons of therapies in the future.

Photopheresis at onset of type 1 diabetes: a randomised, double blind, placebo controlled trial

BACKGROUND

In recent years photopheresis, an extracorporeal form of photochemotherapy using psoralen and ultraviolet A irradiation of leucocytes, has been claimed to be an effective form of immunomodulation.

AIM

To evaluate its effect in type 1 diabetes we performed a double blind, controlled study using placebo tablets and sham pheresis in the control group.

METHODS

A total of 49 children, aged 10-18 years of age at diagnosis of type 1 diabetes were included; 40 fulfilled the study and were followed for three years (19 received active treatment with photopheresis and 21 placebo treatment).

RESULTS

The actively treated children secreted significantly more C peptide in urine during follow up than control children. C peptide values in serum showed corresponding differences between the two groups. The insulin dose/kg body weight needed to achieve satisfactory HbA1c values was always lower in the photopheresis group; there was no difference between the groups regarding HbA1c values during follow up. The treatment was well accepted except for nausea (n = 3) and urticaria (n = 1) in the actively treated group. There were no differences regarding weight or height, or episodes of infection between the two groups during follow up.

CONCLUSION

Photopheresis does have an effect in addition to its possible placebo effect, shown as a weak but significant effect on the disease process at the onset of type 1 diabetes, an effect still noted after three years of follow up.

New therapeutic avenues in autoimmunity

During the last decade, much progress has been made in the understanding of processes that lead to autoimmunity. Cellular interactions mediated through cytokines and adhesion molecules were found to play a major role in the genesis of autoimmune conditions. During this period, we learned to recruit monoclonal antibodies to manipulate these delicate processes and to divert their outcome to a path we control better. Our comprehension of IVIG (intravenous immunoglobulin therapy) has broadened, and new indications for the implementation of this promising therapy have been pursued. In this review, we shed light on new therapeutic modalities that have been published since our previous report and discuss new data concerning the old modalities.

Strategies in immunotherapy of insulin-dependent diabetes mellitus

Complete and definitive prevention of diabetes obtained in animal models by using a number of diversified maneuvers has elicited major hope for immunoprevention of the disease in man. Therapeutic trials of immunosuppressive drugs in human IDDM have opened the way towards prevention or cure of the disease. Difficulties encountered, including requirement for chronic immunosuppression and risk of metabolic relapses, suggest two complementary approaches: precocious intervention based on early and reliable disease prediction, and tolerance-inducing regimens, hopefully using shorter and innocuous therapy. Animal data suggest that this is indeed an achievable goal.