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Historically, type 2 diabetes ( T2D) was considered a metabolic disease of ageing. However, recent discoveries have demonstrated the role of chronic systemic inflammation in the development of insulin resistance and subsequent progression to T2D. Over the years, investigations into the pathophysiology of T2D have identified the presence of islet-specific T cells and islet autoimmune disease in T2D patients. Moreover, the cell-mediated islet autoimmunity has also been correlated with the progressive loss of β-cell function associated with T2D disease pathogenesis. In this manuscript, the involvement of cell-mediated islet autoimmune disease in the progression of T2D disease and the similarities in islet-specific T-cell reactivity between type 1 diabetes ( T1D) and T2D are discussed. [ABSTRACT FROM AUTHOR]

The clinical efficacy of peroxisome proliferator-activated receptor gamma ( PPAR-γ) agonists in cell-mediated autoimmune diseases results from down-regulation of inflammatory cytokines and autoimmune effector cells. T cell islet autoimmunity has been demonstrated to be common in patients with phenotypic type 2 diabetes mellitus ( T2DM) and islet-specific T cells ( T+) to be correlated positively with more severe beta cell dysfunction. We hypothesized that the beneficial effects of the PPAR-γ agonist, rosiglitazone, therapy in autoimmune T2DM patients is due, in part, to the immunosuppressive properties on the islet-specific T cell responses. Twenty-six phenotypic T2DM patients positive for T cell islet autoimmunity ( T+) were identified and randomized to rosiglitazone ( n = 12) or glyburide ( n = 14). Beta cell function, islet-specific T cell responses, interleukin ( IL)-12 and interferon ( IFN)-γ responses and islet autoantibodies were followed for 36 months. Patients treated with rosiglitazone demonstrated significant ( P < 0·03) down-regulation of islet-specific T cell responses, although no change in response to tetanus, a significant decrease ( P < 0·05) in IFN-γ production and significantly ( P < 0·001) increased levels of adiponectin compared to glyburide-treated patients. Glucagon-stimulated beta cell function was observed to improve significantly ( P < 0·05) in the rosiglitazone-treated T2DM patients coinciding with the down-regulation of the islet-specific T cell responses. In contrast, beta cell function in the glyburide-treated T2DM patients was observed to drop progressively throughout the study. Our results suggest that down-regulation of islet-specific T cell autoimmunity through anti-inflammatory therapy may help to improve beta cell function in autoimmune phenotypic T2DM patients. [ABSTRACT FROM AUTHOR]

OTHER THEMES PUBLISHED IN THIS IMMUNOLOGY IN THE CLINIC REVIEW SERIES Allergy, Host Responses, Cancer, Autoinflammatory Diseases, Type 1 diabetes and viruses. Summary Historically, the development of type 2 diabetes has been considered not to have an autoimmune component, in contrast to the autoimmune pathogenesis of type 1 diabetes. In this review we will discuss the accumulating data supporting the concept that islet autoreactivity and inflammation is present in type 2 diabetes pathogenesis, and the islet autoimmunity appears to be one of the factors associated with the progressive nature of the type 2 diabetes disease process. [ABSTRACT FROM AUTHOR]

Background Islet-antigen-specific CD4+ T cells are known to promote auto-immune destruction in T1D. Measuring T-cell number and function provides an important biomarker. In response to this need, we evaluated responses to proinsulin and GAD epitopes in a multicentre study. Methods A tetramer-based assay was used in five participating centres to measure T-cell reactivities to DR0401-restricted epitopes. Three participating centres concurrently performed ELISPOT or immunoblot assays. Each centre used blind-coded, centrally distributed peptide and tetramer reagents. Results All participating centres detected responses to auto-antigens and the positive control antigen, and in some cases cloned the corresponding T cells. However, response rates varied among centres. In total, 74% of patients were positive for at least one islet epitope. The most commonly recognized epitope was GAD270-285. Only a minority of the patients tested by tetramer and ELISPOT were concordant for both assays. Conclusions This study successfully detected GAD and proinsulin responses using centrally distributed blind-coded reagents. Centres with little previous experience using class II tetramer reagents implemented the assay. The variability in response rates observed for different centres suggests technical difficulties and/or heterogeneity within the local patient populations tested. Dual analysis by tetramer and ELISPOT or immunoblot assays was frequently discordant, suggesting that these assays detect distinct cell populations. Future efforts should investigate shared blood samples to evaluate assay reproducibility and longitudinal samples to identify changes in T-cell phenotype that correlate with changes in disease course. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Background Type 1 diabetes (T1D) is a cell-mediated autoimmune disease characterized by destruction of the pancreatic islet cells. The use of cryopreserved cells is preferable to the use of freshly isolated cells to monitor clinical trials to decrease assay and laboratory variability. Methods The T-Cell Workshop Committee of the Immunology of Diabetes Society compared two widely accepted T-cell freezing protocols (warm and cold) to freshly isolated peripheral blood mononuclear cells from patients with T1D and controls in terms of recovery, viability, cell subset composition, and performance in functional assays currently in use in T1D-related research. Nine laboratories participated in the study with four different functional assays included. Results The cold freezing method yielded higher recovery and viability compared with the warm freezing method. Irrespective of freezing protocol, B cells and CD8+ T cells were enriched, monocyte fraction decreased, and islet antigen-reactive responses were lower in frozen versus fresh cells. However, these results need to take in to account that the overall response to islet autoantigens was low in some assays. Conclusions In the current study, none of the tested T-cell functional assays performed well using frozen samples. More research is required to identify a freezing method and a T-cell functional assay that will produce responses in patients with T1D comparable to responses using fresh peripheral blood mononuclear cells. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Autoimmune T cell responses directed against insulin-producing β cells are central to the pathogenesis of type 1 diabetes (T1D). Detection of such responses is therefore critical to provide novel biomarkers for T1D 'immune staging' and to understand the mechanisms underlying the disease. While different T cell assays are being developed for these purposes, it is important to optimize and standardize methods for processing human blood samples for these assays. To this end, we review data relevant to critical parameters in peripheral blood mononuclear cell (PBMC) isolation, (cryo)preservation, distribution and usage for detecting antigen-specific T cell responses. Based on these data, we propose recommendations on processing blood samples for T cell assays and identify gaps in knowledge that need to be addressed. These recommendations may be relevant not only for the analysis of T cell responses in autoimmune disease, but also in cancer and infectious disease, particularly in the context of clinical trials. [ABSTRACT FROM AUTHOR]

Type 1 diabetes (T1D) is an autoimmune disease caused by the T cell-mediated destruction of the pancreatic insulin-producing beta cells. Currently there are no widely accepted and standardized assays available to analyse the function of autoreactive T cells involved in T1D. The development of such an assay would greatly aid efforts to understand the pathogenesis of T1D and is also urgently required to guide the development of antigen-based therapies intended to prevent, or cure, T1D. Here we describe some of the assays used currently to detect autoreactive T cells in human blood and review critically their strengths and weaknesses. The challenges and future prospects for the T cell assays are discussed. [ABSTRACT FROM AUTHOR]

Objective: In patients with long-standing type 1 diabetes, we investigated whether improved beta-cell function can be achieved by combining intensive insulin therapy with agents that may 1) promote beta-cell growth and/or limit beta-cell apoptosis and 2) weaken the anti-beta-cell autoimmunity.Research Design and Methods: For this study, 20 individuals (mean age 39.5 +/- 11.1 years) with long-standing type 1 diabetes (21.3 +/- 10.7 years) were enrolled in this prospective open-label crossover trial. After achieving optimal blood glucose control, 16 subjects were randomized to exenatide with or without daclizumab. Endogenous insulin production was determined by repeatedly measuring serum C-peptide.Results: In 85% of individuals with long-standing type 1 diabetes who were screened for participation in this trial, C-peptide levels >or=0.05 ng/ml (0.02 nmol/l) were found. Residual beta-cells responded to physiological (mixed-meal) and pharmacological (arginine) stimuli. During exenatide treatment, patients lost 4.1 +/- 2.9 kg body wt and insulin requirements declined significantly (total daily dose on exenatide 0.48 +/- 0.11 vs. 0.55 +/- 0.13 units x kg(-1) x day(-1) without exenatide; P = 0.0062). No signs of further activation of the underlying autoimmune disease were observed. Exenatide delayed gastric emptying, suppressed endogenous incretin levels, but did not increase C-peptide secretion.Conclusions: In long-standing type 1 diabetes, which remains an active autoimmune disease even decades after its onset, surviving beta-cells secrete insulin in a physiologically regulated manner. However, the combination of intensified insulin therapy, exenatide, and daclizumab did not induce improved function of these remaining beta-cells. [ABSTRACT FROM AUTHOR]

Latent autoimmune diabetes in adults or type 1.5 diabetes is considered to be a T-cell-mediated autoimmune disease. However, identification of patients is based commonly on autoantibody (Ab) detection. To determine whether measuring T-cell reactivity to islet proteins compared with measuring Abs improves detection of autoimmune diabetes and how beta-cell function correlates with T-cell reactivity compared with Ab positivity, we assessed the T-cell proliferative responses and Ab responses (islet cell autoantibodies, insulin autoantibodies, insulinoma-associated protein-2 autoantibodies, and GAD Abs) to islet proteins of 36 phenotypic type 2 diabetic patients. To be considered Ab(+) or T-cell(+), patients were required to be positive for a minimum of two consecutive time points. beta-Cell function was measured with fasting and glucagon-stimulated C-peptide. Independent of T-cell reactivity, Ab(+) and Ab(-) patients had comparable fasting and glucagon-stimulated C-peptide. Independent of Ab status, T-cell(+) patients demonstrated significantly lower glucagon-stimulated (P < 0.003) C-peptide compared with T-cell(-) patients. These data suggest that measuring T-cell responses to multiple islet proteins in phenotypic type 2 diabetic patients improves identification of patients with autoimmune diabetes and delineates those who have a more severe beta-cell lesion compared with Ab assessment alone. [ABSTRACT FROM AUTHOR]

Type 1 diabetes is a chronic autoimmune disease mediated by autoreactive T-cells. Several experimental therapies targeting T-cells are in clinical trials. To understand how these therapies affect T-cell responses in vivo, assays that directly measure human T-cell function are needed. In a blinded, multicenter, case-controlled study conducted by the Immune Tolerance Network, we tested responses in an immunoblot and T-cell proliferative assay to distinguish type 1 diabetic patients from healthy control subjects. Peripheral blood cells from 39 healthy control subjects selected for DR4 and 23 subjects with recently diagnosed type 1 diabetes were studied. Autoantibody responses were measured in serum samples. Positive responses in both assays were more common in peripheral blood mononuclear cells from new-onset type 1 diabetic patients compared with control subjects. The proliferative, immunoblot, and autoantibody assays had sensitivities of 58, 91, and 78% with specificities of 94, 83, and 85%, respectively. When cellular assays were combined with autoantibody measurements, the sensitivity of the measurements was 75% with 100% specificity. We conclude that cellular assays performed on peripheral blood have a high degree of accuracy in discriminating responses in subjects with type 1 diabetes from healthy control subjects. They may be useful for assessment of cellular autoimmune responses involved in type 1 diabetes. [ABSTRACT FROM AUTHOR]

Type 1 diabetes is a cell-mediated autoimmune disease characterized by autoantibody and peripheral blood mononuclear cell (PBMC) reactivity to islet cell proteins. Type 2 diabetes is not an autoimmune disease but rather results from both insulin resistance and a nonautoimmune insulin secretory defect. There is, however, a group of phenotypic type 2 diabetic patients who have islet autoantibodies that are similar to those of type 1 diabetic patients. In this study, we investigated, using cellular immunoblotting, whether type 2 diabetic patients positive for islet autoantibodies have PBMC responses to islet proteins. We observed that autoantibody negative (Ab-) type 2 diabetic patients (n = 9) and normal control subjects (n = 12) demonstrated PBMCs responsive to 0-3 molecular weight regions. In contrast, autoantibody positive (Ab+) type 2 diabetic patients (n = 11) demonstrated PBMC responses to 3-18 molecular weight regions, similar to that of type 1 diabetic patients (responsive to 4-18 molecular weight regions). PBMCs from over 90% of the Ab+ type 2 and type 1 diabetic patients were observed to proliferate to islet proteins in the vicinity of 97 kDa. In contrast, 65-90% of type 1 diabetic patients had responsive PBMCs for islet proteins in most of the molecular weight regions, whereas <60% of the Ab+ type 2 diabetic patients had PBMCs responsive to the same molecular weight proteins. Ab+ type 2 diabetic patients appear to be heterogeneous with respect to cellular reactivity to islet proteins. Some subjects demonstrate PBMC responses similar to those of "classic" type 1 diabetic patients, whereas others have PBMC responses potentially distinct from type 1 diabetic patients. [ABSTRACT FROM AUTHOR]