Analysis of T-cell assays to measure autoimmune responses in subjects with type 1 diabetes: results of a blinded controlled study

Islet Autoimmunity is Highly Prevalent and Associated With Diminished β-Cell Function in Patients With Type 2 Diabetes in the Grade Study

Islet autoimmunity may contribute to β-cell dysfunction in type 2 diabetes (T2D). Its prevalence and clinical significance have not been rigorously determined. In this ancillary study to the Glycemia Reduction Approaches in Diabetes-A Comparative Effectiveness (GRADE) Study, we investigated the prevalence of cellular and humoral islet autoimmunity in patients with T2D duration 4·0±3·0 y, HbA1c 7·5±0·5% on metformin alone. We measured T cell autoreactivity against islet proteins, islet autoantibodies against GAD65, IA2, ZnT8, and β-cell function. Cellular islet autoimmunity was present in 41·3%, humoral islet autoimmunity in 13·5%, and both in 5·3%. β-cell function calculated as iAUC-CG and ΔC-peptide(0- 30)/Δglucose(0-30) from an oral glucose tolerance test was lower among T cell-positives (T+) than T cell-negatives (T-) using two different adjustments for insulin sensitivity (iAUC-CG: 13·2% [95% CI 0·3, 24·4%] or 11·4% [95% CI 0·4, 21·2%] lower; ΔC-peptide(0-30)/Δglucose(0-30)) 19% [95% CI 3·1, 32·3%] or 17·7% [95% CI 2·6, 30·5%] lower). T+ patients had 17% higher HbA1c (95% CI 0·07, 0·28) and 7·7 mg/dL higher fasting plasma glucose levels (95% CI 0·2,15·3) than T- patients. We conclude that islet autoimmunity is much more prevalent in T2D patients than previously reported. T cell-mediated autoimmunity is associated with diminished β-cell function and worse glycemic control.

Assay format diversity in pre-clinical immunogenicity risk assessment: Toward a possible harmonization of antigenicity assays

A major impediment to successful use of therapeutic protein drugs is their ability to induce anti-drug antibodies (ADA) that can alter treatment efficacy and safety in a significant number of patients. To this aim, in silico, in vitro, and in vivo tools have been developed to assess sequence and other liabilities contributing to ADA development at different stages of the immune response. However, variability exists between similar assays developed by different investigators due to the complexity of assays, a degree of uncertainty about the underlying science, and their intended use. The impact of protocol variations on the outcome of the assays, i.e., on the immunogenicity risk assigned to a given drug candidate, cannot always be precisely assessed. Here, the Non-Clinical Immunogenicity Risk Assessment working group of the European Immunogenicity Platform (EIP) reviews currently used assays and protocols and discusses feasibility and next steps toward harmonization and standardization.

Impact of T cells on neurodegeneration in anti-GAD65 limbic encephalitis

Objective

Direct pathogenic effects of autoantibodies to the 65 kDa isoform of glutamic acid decarboxylase (GAD65) in autoimmune limbic encephalitis (LE) have been questioned due to its intracellular localization. We therefore hypothesized a pathogenic role for T cells.

Methods

We assessed magnet resonance imaging, neuropsychological and peripheral blood, and CSF flow cytometry data of 10 patients with long‐standing GAD65‐LE compared to controls in a cross‐sectional manner. These data were related to each other within the GAD65‐LE group and linked to neuropathological findings in selective hippocampectomy specimen from another two patients. In addition, full‐resolution human leukocyte antigen (HLA) genotyping of all patients was performed.

Results

Compared to controls, no alteration in hippocampal volume but impaired memory function and elevated fractions of activated HLADR⁺ CD4⁺ and CD8⁺ T cells in peripheral blood and cerebrospinal fluid were found. Intrathecal fractions of CD8⁺ T cells negatively correlated with hippocampal volume and memory function, whereas the opposite was true for CD4⁺ T cells. Consistently, antigen‐experienced CD8⁺ T cells expressed increased levels of the cytotoxic effector molecule perforin in peripheral blood, and perforin‐expressing CD8⁺ T cells were found attached mainly to small interneurons but also to large principal neurons together with wide‐spread hippocampal neurodegeneration. 6/10 LE patients harbored the HLA‐A*02:01 allele known to present the immunodominant GAD65_114–123 peptide in humans.

Interpretation

Our data suggest a pathogenic effect of CD8⁺ T cells and a regulatory effect of CD4⁺ T cells in patients with long‐standing GAD65‐LE.

Islet Autoimmunity in Adults With Impaired Glucose Tolerance and Recently Diagnosed, Treatment Naïve Type 2 Diabetes in the Restoring Insulin SEcretion (RISE) Study

The presence of islet autoantibodies and islet reactive T cells (T+) in adults with established type 2 diabetes (T2D) have been shown to identify those patients with more severe β-cell dysfunction. However, at what stage in the progression toward clinical T2D does islet autoimmunity emerge as an important component influencing β-cell dysfunction? In this ancillary study to the Restoring Insulin SEcretion (RISE) Study, we investigated the prevalence of and association with β-cell dysfunction of T+ and autoantibodies to the 65 kDa glutamic acid decarboxylase antigen (GADA) in obese pre-diabetes adults with impaired glucose tolerance (IGT) and recently diagnosed treatment naïve (Ndx) T2D. We further investigated the effect of 12 months of RISE interventions (metformin or liraglutide plus metformin, or with 3 months of insulin glargine followed by 9 months of metformin or placebo) on islet autoimmune reactivity. We observed GADA(+) in 1.6% of NdxT2D and 4.6% of IGT at baseline, and in 1.6% of NdxT2D and 5.3% of IGT at 12 months, but no significant associations between GADA(+) and β-cell function. T(+) was observed in 50% of NdxT2D and 60.4% of IGT at baseline, and in 68.4% of NdxT2D and 83.9% of IGT at 12 months. T(+) NdxT2D were observed to have significantly higher fasting glucose (p = 0.004), and 2 h glucose (p = 0.0032), but significantly lower steady state C-peptide (sscpep, p = 0.007) compared to T(-) NdxT2D. T(+) IGT participants demonstrated lower but not significant (p = 0.025) acute (first phase) C-peptide response to glucose (ACPRg) compared to T(-) IGT. With metformin treatment, T(+) participants were observed to have a significantly lower Hemoglobin A1c (HbA1c, p = 0.002) and fasting C-peptide (p = 0.002) compared to T(-), whereas T(+) treated with liraglutide + metformin had significantly lower sscpep (p = 0.010) compared to T(-) participants. In the placebo group, T(+) participants demonstrated significantly lower ACPRg (p = 0.001) compared to T(-) participants. In summary, T(+) were found in a large percentage of obese pre-diabetes adults with IGT and in recently diagnosed T2D. Moreover, T(+) were significantly correlated with treatment effects and β-cell dysfunction. Our results demonstrate that T(+) are an important component in T2D.

Optimization of a Method to Detect Autoantigen-Specific T-Cell Responses in Type 1 Diabetes

The development of tolerizing therapies aiming to inactivate autoreactive effector T-cells is a promising therapeutic approach to control undesired autoimmune responses in human diseases such as Type 1 Diabetes (T1D). A critical issue is a lack of sensitive and reproducible methods to analyze antigen-specific T-cell responses, despite various attempts. We refined a proliferation assay using the fluorescent dye 5,6-carboxylfluorescein diacetate succinimidyl ester (CFSE) to detect responding T-cells, highlighting the fundamental issues to be taken into consideration to monitor antigen-specific responses in patients with T1D. The critical elements that maximize detection of antigen-specific responses in T1D are reduction of blood storage time, standardization of gating parameters, titration of CFSE concentration, selecting the optimal CFSE staining duration and the duration of T-cell stimulation, and freezing in medium containing human serum. Optimization of these elements enables robust, reproducible application to longitudinal cohort studies or clinical trial samples in which antigen-specific T-cell responses are relevant, and adaptation to other autoimmune diseases.

Guidelines for analysis of low-frequency antigen-specific T cell results: Dye-based proliferation assay vs 3H-thymidine incorporation

It is generally recognized that dysregulation of the immune system plays a critical role in many diseases, including autoimmune diseases and cancer. T cells play a crucial role in maintaining self-tolerance, while loss of immune tolerance and T cell activation can lead to severe inflammation and tissue damage. T cell responses have a key role in the effectiveness of vaccination strategies and immunomodulating therapies. Immunomonitoring methods have the ability to elucidate immunological processes, monitor the development of disease and assess therapeutic effects. In this respect, it is of particular interest to evaluate antigen (Ag)-specific T cells by determining their frequency, type and functionality in cellular assays. Nevertheless, Ag-specific T cells are detected infrequently in most diseases using current techniques. Many efforts have been made to develop more sensitive, reproducible, and reliable methods for Ag-specific T cell detection. It has been found that analysis of cellular proliferation can be a useful tool to determine the presence and frequency of Ag-specific T cell and to provides insight into modulation of the T cell response by a specific antigen or therapy. However, the selection of a cut-off value for a positive response and therefore a more accurate interpretation of the data, continues to be a major concern. Here, we provide guidelines to select a proper cut-off for monitoring of Ag-specific CD4⁺ T cell responses. In vitro Ag-stimulation has been assessed with two methods; a dye-based proliferation assay and ³H-thymidine-based assay. Two cut-off approaches are compared; mean and variance of control wells, and the stimulation index. By evaluating the proliferative response to the in vitro Ag-stimulation using these two methods, we demonstrate the importance of taking into consideration the variability of the control wells to distinguish a positive from a false positive response.

Past, present and future of latent autoimmune diabetes in adults

Latent autoimmune diabetes in adults (LADA) is the most common form of autoimmune diabetes diagnosed in adults. Similar to type 1 diabetes, the prevalence of LADA is impacted by ethnicity and geography. LADA is characterized by β cell loss due to autoimmunity and insulin resistance and has highly heterogeneous clinical features, autoimmunity, and genetics in a glutamic acid decarboxylase antibody (GADA) titre-dependent manner, suggesting LADA is part of a continuum spectrum between type 1 and type 2 diabetes. Although LADA is the most frequent form of autoimmune diabetes diagnosed in adults, clinical trials involving LADA are scarce. Here we review the recent advancements in LADA epidemiology, clinical features, pathogenesis, and interventions. We also highlight the environmental factors that are thought to play an important role in addition to genetics in the pathogenesis of LADA. In the future, high-throughput molecular profiles might shed light on the nature of LADA among the wide spectrum of diabetes and offer new opportunities to identify novel LADA-specific biomarkers.

Impaired Phagocytosis in Dendritic Cells From Pediatric Patients With Type 1 Diabetes Does Not Hamper Their Tolerogenic Potential

Type 1 diabetes (T1D) is prompted by defective immunological tolerance, an event in which dendritic cells (DCs) are crucial as immune response orchestrators. In fact, they contribute to maintaining tolerance to self-antigens, but they can also prompt an immunogenic response against them, leading to autoimmunity. Countless factors can potentially impact on the proper functionality of the DCs, which range from altered subset distribution, impaired phagocytic function to abnormal gene expression. Moreover, in T1D, metabolic dysregulation could impair DC functions as well. Indeed, since T1D clinical course is likely to be more aggressive in children and adolescents and entails severe dysglycemia, the aim of this study was to analyze circulating DCs subpopulations in pediatric T1D at different stages, as well as to characterize their phagocytosis ability and tolerance induction potential. Thus, pediatric patients newly diagnosed with T1D, with established disease and control subjects were recruited. Firstly, DCs subsets from peripheral blood were found quantitatively altered during the first year of disease, but recovered in the second year of progression. Secondly, to study the tolerogenic functionality of DCs, liposomes with phosphatidylserine (PS) were designed to mimic apoptotic beta cells, which are able to induce tolerance, as previously demonstrated by our group in DCs from adult patients with T1D. In this study, monocyte-derived DCs from pediatric patients with T1D and control subjects were assessed in terms of PS-liposomes capture kinetics, and transcriptional and phenotypic changes. DCs from pediatric patients with T1D were found to phagocyte PS-liposomes more slowly and less efficiently than DCs from control subjects, inversely correlating with disease evolution. Nonetheless, the transcription of PS receptors and immunoregulatory genes, cytokine profile, and membrane expression of immunological markers in DCs was consistent with tolerogenic potential after PS-liposomes phagocytosis. In conclusion, T1D progression in childhood entails altered peripheral blood DCs subsets, as well as impaired DCs phagocytosis, although tolerance induction could still function optimally. Therefore, this study provides useful data for patient follow-up and stratification in immunotherapy clinical trials.

Standardizing T-Cell Biomarkers in Type 1 Diabetes: Challenges and Recent Advances

Type 1 diabetes (T1D) results from the progressive destruction of pancreatic β-cells in a process mediated primarily by T lymphocytes. The T1D research community has made dramatic progress in understanding the genetic basis of the disease as well as in the development of standardized autoantibody assays that inform both disease risk and progression. Despite these advances, there remains a paucity of robust and accepted biomarkers that can effectively inform on the activity of T cells during the natural history of the disease or in response to treatment. In this article, we discuss biomarker development and validation efforts for evaluation of T-cell responses in patients with and at risk for T1D as well as emerging technologies. It is expected that with systematic planning and execution of a well-conceived biomarker development pipeline, T-cell-related biomarkers would rapidly accelerate disease progression monitoring efforts and the evaluation of intervention therapies in T1D.

Type 2 Diabetes: How Much of an Autoimmune Disease?

Type 2 diabetes (T2D) is characterized by a progressive status of chronic, low-grade inflammation (LGI) that accompanies the whole trajectory of the disease, from its inception to complication development. Accumulating evidence is disclosing a long list of possible "triggers" of inflammatory responses, many of which are promoted by unhealthy lifestyle choices and advanced age. Diabetic patients show an altered number and function of immune cells, of both innate and acquired immunity. Reactive autoantibodies against islet antigens can be detected in a subpopulation of patients, while emerging data are also suggesting an altered function of specific T lymphocyte populations, including T regulatory (Treg) cells. These observations led to the hypothesis that part of the inflammatory response mounting in T2D is attributable to an autoimmune phenomenon. Here, we review recent data supporting this framework, with a specific focus on both tissue resident and circulating Treg populations. We also propose that selective interception (or expansion) of T cell subsets could be an alternative avenue to dampen inappropriate inflammatory responses without compromising immune responses.

Phosphatidylserine-Liposomes Promote Tolerogenic Features on Dendritic Cells in Human Type 1 Diabetes by Apoptotic Mimicry

Type 1 diabetes (T1D) is a metabolic disease caused by the autoimmune destruction of insulin-producing β-cells. With its incidence increasing worldwide, to find a safe approach to permanently cease autoimmunity and allow β-cell recovery has become vital. Relying on the inherent ability of apoptotic cells to induce immunological tolerance, we demonstrated that liposomes mimicking apoptotic β-cells arrested autoimmunity to β-cells and prevented experimental T1D through tolerogenic dendritic cell (DC) generation. These liposomes contained phosphatidylserine (PS)—the main signal of the apoptotic cell membrane—and β-cell autoantigens. To move toward a clinical application, PS-liposomes with optimum size and composition for phagocytosis were loaded with human insulin peptides and tested on DCs from patients with T1D and control age-related subjects. PS accelerated phagocytosis of liposomes with a dynamic typical of apoptotic cell clearance, preserving DCs viability. After PS-liposomes phagocytosis, the expression pattern of molecules involved in efferocytosis, antigen presentation, immunoregulation, and activation in DCs concurred with a tolerogenic functionality, both in patients and control subjects. Furthermore, DCs exposed to PS-liposomes displayed decreased ability to stimulate autologous T cell proliferation. Moreover, transcriptional changes in DCs from patients with T1D after PS-liposomes phagocytosis pointed to an immunoregulatory prolife. Bioinformatics analysis showed 233 differentially expressed genes. Genes involved in antigen presentation were downregulated, whereas genes pertaining to tolerogenic/anti-inflammatory pathways were mostly upregulated. In conclusion, PS-liposomes phagocytosis mimics efferocytosis and leads to phenotypic and functional changes in human DCs, which are accountable for tolerance induction. The herein reported results reinforce the potential of this novel immunotherapy to re-establish immunological tolerance, opening the door to new therapeutic approaches in the field of autoimmunity.

Comparative Pathogenesis of Autoimmune Diabetes in Humans, NOD Mice, and Canines: Has a Valuable Animal Model of Type 1 Diabetes Been Overlooked?

Despite decades of research in humans and mouse models of disease, substantial gaps remain in our understanding of pathogenic mechanisms underlying the development of type 1 diabetes. Furthermore, translation of therapies from preclinical efforts capable of delaying or halting β-cell destruction has been limited. Hence, a pressing need exists to identify alternative animal models that reflect human disease. Canine insulin deficiency diabetes is, in some cases, considered to follow autoimmune pathogenesis, similar to NOD mice and humans, characterized by hyperglycemia requiring lifelong exogenous insulin therapy. Also similar to human type 1 diabetes, the canonical canine disorder appears to be increasing in prevalence. Whereas islet architecture in rodents is distinctly different from humans, canine pancreatic endocrine cell distribution is more similar. Differences in breed susceptibility alongside associations with MHC and other canine immune response genes parallel that of different ethnic groups within the human population, a potential benefit over NOD mice. The impact of environment on disease development also favors canine over rodent models. Herein, we consider the potential for canine diabetes to provide valuable insights for human type 1 diabetes in terms of pancreatic histopathology, impairment of β-cell function and mass, islet inflammation (i.e., insulitis), and autoantibodies specific for β-cell antigens.

Neuronal T-cell autoreactivity is amplified in overweight children with new-onset insulin-requiring diabetes

OBJECTIVE

Disease-associated T-cell autoreactivities are seen in most type 1 diabetic patients and are thought to emerge before islet autoantibodies, but host factors that impact autoimmune elements remain uncertain. We assessed if adiposity and measures of insulin sensitivity impact T- and B-cell autoimmunity in children with insulin-requiring diabetes.

RESEARCH DESIGN AND METHODS

Insulin-requiring children and adolescents diagnosed between January 2004 and June 2008 were studied (n = 261): age 9.7 ± 4 years, 92% white, and 60% male. T-cell responses to 10 diabetes-associated antigens, β-cell autoantibodies (GADA, IA-2A, IAA, and ICA), BMI z score (BMIz), and waist percentile were measured at onset and 3 months later.

RESULTS

All but one subject had either T- or B-cell autoimmunity. Diabetes-associated T-cell autoreactivities were found in 92% of subjects. Higher amplitude T-cell autoreactivities to neuronal diabetes-associated autoantigens were seen in those with the highest BMIz quintile, BMI ≥85th percentile (P < 0.05), and waist circumference ≥85th percentile (P < 0.05). There were no relationships between the number of T-cell reactivities or T-cell diversity with adiposity measures or autoantibody number or type. Patients with positive T-cell reactivities but without autoantibodies had the highest BMIz (P = 0.006).

CONCLUSIONS

Our observations link obesity and diabetes-related autoimmunity, suggesting an amplification of neuronal T-cell autoimmunity associated with adiposity and/or insulin resistance, with obesity-related inflammation possibly enhancing islet autoimmunity.

Impact of islet autoimmunity on the progressive β-cell functional decline in type 2 diabetes

OBJECTIVE

Cross-sectional studies have suggested that islet autoimmunity may be more prevalent in type 2 diabetes (T2D) than previously appreciated and may contribute to the progressive decline in β-cell function. In this study, we longitudinally evaluated the effect of islet autoimmune development on the progressive β-cell dysfunction in T2D patients.

RESEARCH DESIGN AND METHODS

Twenty-three T2D patients negative for islet autoantibodies (GAD antibody and insulinoma-associated protein 2) and islet-specific T cells were evaluated prospectively for up to 36 months. We investigated the percentage of patients who developed islet autoantibodies (Ab+) and/or islet-reactive T cells (T+) and the effect of the islet autoimmunity on fasting and glucagon-stimulated C-peptide responses. We defined positive islet autoimmunity as Ab+ and/or T+ for at least two study visits.

RESULTS

Of the 23 patients, 6 (26%) remained negative for islet autoimmunity (Ab-T-), 14 (61%) developed Ab+ and/or T+, and 3 (13%) were unclassifiable because they developed islet autoimmunity at only one study visit. Islet Ab+ was observed to be less stable than islet-specific T-cell responses. Development of islet autoimmunity was significantly associated with a more rapid decline in fasting (P < 0.0001) and glucagon-stimulated (P < 0.05) C-peptide responses.

CONCLUSIONS

These pilot data suggest that the development of islet autoimmunity in T2D is associated with a significantly more rapid β-cell functional decline.

Established and emerging biomarkers for the prediction of type 1 diabetes: a systematic review

Type 1 diabetes (T1D) is an autoimmune disease with a prolonged and variable latent period that culminates in the destruction of pancreatic β-cells and the development of hyperglycemia. There is a need for diagnostic biomarkers to detect more accurately individuals with prediabetes to expedite targeting for prevention and intervention strategies. To assess the current ability to predict the insidious development of T1D, we conducted a comprehensive systematic review for established and prospective predictive markers of T1D using the Medline, OVID, and EMBASE databases. Resulting citations were screened for relevance to subject. Our research generated five major categories of markers that are either currently used or forthcoming: genetic, autoantibody, risk score quantification, cellular immunity, and β-cell function. The current standard used to assess T1D onset or predisposition focuses on autoimmune pathology and disease-associated autoantibodies. Research studies in general go beyond autoantibody screening and assess genetic predisposition, and quantitate risk of developing disease based on additional factors. However, there are few currently used techniques that assess the root of T1D: β-cell destruction. Thus, novel techniques are discussed with the potential to gauge degrees of β-cell stress and failure via protein, RNA, and DNA analyses.

Biomarkers in type 1 diabetes: application to the clinical trial setting

PURPOSE OF REVIEW

Biomarkers of type 1 diabetes (T1D) are important for assessing risk of developing disease, monitoring disease progression, and determining responses to clinical treatments. Here we review recent advances in the development of biomarkers of T1D with a focus on their utility in clinical trials.

RECENT FINDINGS

Measurements of autoantibodies and metabolic outcomes have been the foundation of monitoring T1D for the past 20 years. Recent advancements have led to improvements in T-cell-specific assays that have been used in large-scale clinical trials to measure antigen-specific T cell responses. Additionally, new tools are being developed for the measurement of β cell mass and death that will allow for more direct measurement of disease activity. Lastly, recent studies have used both immunologic and nonimmunologic biomarkers to identify responders to treatments in clinical trials.

SUMMARY

Use of biomarkers in the study of T1D has largely not changed over the past 20 years; however, recent advancements in the field are establishing new techniques that allow for more precise monitoring of disease progression. These new tools will ultimately lead to an improvement in understanding of disease and will be utilized in clinical trials.

Large-scale prospective T cell function assays in shipped, unfrozen blood samples: experiences from the multicenter TRIGR trial

Broad consensus assigns T lymphocytes fundamental roles in inflammatory, infectious, and autoimmune diseases. However, clinical investigations have lacked fully characterized and validated procedures, equivalent to those of widely practiced biochemical tests with established clinical roles, for measuring core T cell functions. The Trial to Reduce Insulin-dependent diabetes mellitus in the Genetically at Risk (TRIGR) type 1 diabetes prevention trial used consecutive measurements of T cell proliferative responses in prospectively collected fresh heparinized blood samples shipped by courier within North America. In this article, we report on the quality control implications of this simple and pragmatic shipping practice and the interpretation of positive- and negative-control analytes in our assay. We used polyclonal and postvaccination responses in 4,919 samples to analyze the development of T cell immunocompetence. We have found that the vast majority of the samples were viable up to 3 days from the blood draw, yet meaningful responses were found in a proportion of those with longer travel times. Furthermore, the shipping time of uncooled samples significantly decreased both the viabilities of the samples and the unstimulated cell counts in the viable samples. Also, subject age was significantly associated with the number of unstimulated cells and T cell proliferation to positive activators. Finally, we observed a pattern of statistically significant increases in T cell responses to tetanus toxin around the timing of infant vaccinations. This assay platform and shipping protocol satisfy the criteria for robust and reproducible long-term measurements of human T cell function, comparable to those of established blood biochemical tests. We present a stable technology for prospective disease-relevant T cell analysis in immunological diseases, vaccination medicine, and measurement of herd immunity.

Islet-specific T-cell responses and proinflammatory monocytes define subtypes of autoantibody-negative ketosis-prone diabetes

OBJECTIVE

Ketosis-prone diabetes (KPD) is characterized by diabetic ketoacidosis (DKA) in patients lacking typical features of type 1 diabetes. A validated classification scheme for KPD includes two autoantibody-negative ("A-") phenotypic forms: "A-β-" (lean, early onset, lacking β-cell functional reserve) and "A-β+" (obese, late onset, with substantial β-cell functional reserve after the index episode of DKA). Recent longitudinal analysis of a large KPD cohort revealed that the A-β+ phenotype includes two distinct subtypes distinguished by the index DKA episode having a defined precipitant ("provoked," with progressive β-cell function loss over time) or no precipitant ("unprovoked," with sustained β-cell functional reserve). These three A- KPD subtypes are characterized by absence of humoral islet autoimmune markers, but a role for cellular islet autoimmunity is unknown.

RESEARCH DESIGN AND METHODS

Islet-specific T-cell responses and the percentage of proinflammatory (CD14+CD16+) blood monocytes were measured in A-β- (n = 7), provoked A-β+ (n = 15), and unprovoked A-β+ (n = 13) KPD patients. Genotyping was performed for type 1 diabetes-associated HLA class II alleles.

RESULTS

Provoked A-β+ and A-β- KPD patients manifested stronger islet-specific T-cell responses (P < 0.03) and higher percentages of proinflammatory CD14+CD16+ monocytes (P < 0.01) than unprovoked A-β+ KPD patients. A significant relationship between type 1 diabetes HLA class II protective alleles and negative T-cell responses was observed.

CONCLUSIONS

Provoked A-β+ KPD and A-β- KPD are associated with a high frequency of cellular islet autoimmunity and proinflammatory monocyte populations. In contrast, unprovoked A-β+ KPD lacks both humoral and cellular islet autoimmunity.

Islet autoimmunity in phenotypic type 2 diabetes patients

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.

Attenuation of islet-specific T cell responses is associated with C-peptide improvement in autoimmune type 2 diabetes patients

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.

ZnT8-Specific CD4+ T cells display distinct cytokine expression profiles between type 1 diabetes patients and healthy adults

Determination of antigen-specific T cell repertoires in human blood has been a challenge. Here, we show a novel integrated approach that permits determination of multiple parameters of antigen-specific T cell repertoires. The approach consists of two assays: the Direct assay and the Cytokine-driven assay. Briefly, human PBMCs are first stimulated with overlapping peptides encoding a given antigen for 48 hours to measure cytokine secretion (Direct assay). Peptide-reactive T cells are further expanded by IL-2 for 5 days; and after overnight starvation, expanded cells are stimulated with the same peptides from the initial culture to analyze cytokine secretion (Cytokine-driven assay). We first applied this integrated approach to determine the type of islet-antigen-specific T cells in healthy adults. Out of ten donors, the Direct assay identified GAD65-specific CD4⁺ T cells in three adults and zinc transporter 8 (ZnT8)-specific CD4⁺ T cells in five adults. The intracytoplasmic cytokine staining assay showed that these islet-antigen-specific CD4⁺ T cells belonged to the CD45RO⁺ memory compartment. The Cytokine-driven assay further revealed that islet-antigen-specific CD4⁺ T cells in healthy adults were capable of secreting various types of cytokines including type 1 and type 2 cytokines as well as IL-10. We next applied our integrated assay to determine whether the type of ZnT8-specific CD4⁺ T cells is different between Type 1 diabetes patients and age/gender/HLA-matched healthy adults. We found that ZnT8-specific CD4⁺ T cells were skewed towards Th1 cells in T1D patients, while Th2 and IL-10-producing cells were prevalent in healthy adults. In conclusion, the Direct assay and the Cytokine-driven assay complement each other, and the combination of the two assays provides information of antigen-specific T cell repertoires on the breadth, type, and avidity. This strategy is applicable to determine the differences in the quality of antigen-specific T cells between health and disease.

Recognition of heat shock protein 60 epitopes in children with type 1 diabetes

BACKGROUND

Treatment with a specific HSP60 epitope in new onset of type 1 diabetes (T1D) patients has been shown to preserve endogenous insulin production. Previously, recognition of pan HLA-DR-binding HSP60 epitopes in various autoimmune diseases was found; this study investigated recognition of these epitopes in newly diagnosed T1D patients and correlated findings to the occurrence of a partial remission.

METHODS

Peripheral blood mononuclear cells of 18 children with T1D were prospectively collected at disease onset and a few months after diagnosis. Epitope-specific T-cell proliferation and cytokine production (intracellular and in culture supernatants) were measured. Results were compared with 31 longstanding T1D patients and ten healthy controls.

RESULTS

Although HSP60 epitope-specific T-cell proliferative responses were detected, overall proliferative responses were low. At onset, epitope-specific intracellular IFN-γ production was higher in T1D patients compared with healthy controls (p < 0.05). At follow-up, both IL-10 and IFN-γ production were higher in those without a partial remission than in those with a partial remission (both p < 0.05). Also, IL-10 and IFN-γ production were higher compared with onset for patients without a PR (both p < 0.01). In supernatants of HSP60 epitope-specific T-cell cultures, no substantial differences in cytokine production were found between T1D patients with and without a partial remission, either at onset or a few months after onset. As patient numbers were small, results should be interpreted with caution.

CONCLUSIONS

Pan-DR-binding HSP60 peptides induced low peptide-specific proliferative responses and peptide-specific production of some, mainly intracellular, cytokines in T1D patients. Recognition did not differ significantly between patient groups and various time points.

Immunologic and metabolic biomarkers of β-cell destruction in the diagnosis of type 1 diabetes

Type 1 diabetes (T1D), also known as insulin-dependent diabetes mellitus, is a chronic disorder that results from autoimmune destruction of insulin-producing β cells in the islets of Langerhans within the pancreas ( Atkinson and Maclaren 1994). This disease becomes clinically apparent only after significant destruction of the β-cell mass, which reduces the ability to maintain glycemic control and metabolic function. In addition, it continues for years after clinical onset until, generally, there is complete destruction of insulin secretory capacity. Because prevention and therapy strategies are targeted to this pathologic process, it becomes imperative to have methods with which it can be monitored. This work discusses current research-based approaches to monitor the autoimmunity and metabolic function in T1D patients and their potential for widespread clinical application.

Immunology in the Clinic Review Series; focus on metabolic diseases: development of islet autoimmune disease in type 2 diabetes patients: potential sequelae of chronic inflammation

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.

MRI parameters for prediction of multiple sclerosis diagnosis in children with acute CNS demyelination: a prospective national cohort study

BACKGROUND

Multiple sclerosis (MS) diagnostic criteria incorporate MRI features that can be used to predict later diagnosis of MS in adults with acute CNS demyelination. To identify MRI predictors of a subsequent MS diagnosis in a paediatric population, we created a standardised scoring method and applied it to MRI scans from a national prospective incidence cohort of children with CNS demyelination.

METHODS

Clinical and MRI examinations were done at the onset of acute CNS demyelination and every 3 months in the first year after that, and at the time of a second demyelinating attack. MS was diagnosed on the basis of clinical or MRI evidence of relapsing disease. Baseline MRI scans were assessed for the presence of 14 binary response parameters. Parameters were assessed with a multiple tetrachoric correlation matrix. Univariate analyses and multivariable Cox proportional hazards models were used to identify predictors of MS.

FINDINGS

Between Sept 1, 2004, and June 30, 2010, 332 children and adolescents were assessed for eligibility. 1139 scans were available from 284 eligible participants who had been followed up for 3·9 (SD 1·7) years. 57 (20%) were diagnosed with MS after a median of 188 (IQR 144-337) days. Seven of 14 binary response parameters were retained. The presence of either one or more T1-weighted hypointense lesions (hazard ratio 20·6, 95% CI 5·46-78·0) or one or more periventricular lesions (3·34, 1·27-8·83) was associated with an increased likelihood of MS diagnosis (sensitivity 84%, specificity 93%, positive predictive value 76%, negative predictive value 96%). Risk for MS diagnosis was highest when both parameters were present (34·27, 16·69-70·38). Although the presence of contrast enhancement, cerebral white matter, intracallosal, and brainstem lesions was associated with MS in the univariate analyses, these parameters were not retained in the multivariable models.

INTERPRETATION

Specific MRI parameters can be used to predict diagnosis of MS in children with incident demyelination of the CNS. The ability to promptly identify children with MS will enhance timely access to care and will be important for future clinical trials in paediatric MS.

FUNDING

Canadian Multiple Sclerosis Scientific Research Foundation.

Immunology of Diabetes Society T-Cell Workshop: HLA class II tetramer-directed epitope validation initiative

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.

Comparison of cryopreservation methods on T-cell responses to islet and control antigens from type 1 diabetic patients and controls

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.

Pathogenic and regulatory T cells in type 1 diabetes: losing self-control, restoring it, and how to take the temperature

The central role of T cells in type 1 diabetes pathogenesis is well established, but these cells continue to pose numerous challenges in understanding their dynamics and in following their modifications. Important progress has been recently made in pinpointing some novel antigens targeted by pathogenic T cells and the epitope sequences recognized. Studies on the interplay between effector T cells, their regulatory counterparts, and cells of the innate immune system have unraveled novel pathways and may inspire new therapeutic approaches. At the same time, the appreciation of the plasticity of regulatory T cells has raised important caveats on their use for cell-based therapies. Continuous development of T-cell assays exploring both pathogenic and regulatory players will be critical to "take the temperature" of undergoing disease progression and reversal.

Beyond the hormone: insulin as an autoimmune target in type 1 diabetes

Insulin is not only the hormone produced by pancreatic β-cells but also a key target antigen of the autoimmune islet destruction leading to type 1 diabetes. Despite cultural biases between the fields of endocrinology and immunology, these two facets should not be regarded separately, but rather harmonized in a unifying picture of diabetes pathogenesis. There is increasing evidence suggesting that metabolic factors (β-cell dysfunction, insulin resistance) and immunological components (inflammation and β-cell-directed adaptive immune responses) may synergize toward islet destruction, with insulin standing at the crossroad of these pathways. This concept further calls for a revision of the classical dichotomy between type 1 and type 2 diabetes because metabolic and immune mechanisms may both contribute to different extents to the development of different forms of diabetes. After providing a background on the mechanisms of β-cell autoimmunity, we will explain the role of insulin and its precursors as target antigens expressed not only by β-cells but also in the thymus. Available knowledge on the autoimmune antibody and T-cell responses against insulin will be summarized. A unifying scheme will be proposed to show how different aspects of insulin biology may lead to β-cell destruction and may be therapeutically exploited. We will argue about possible reasons why insulin remains the mainstay of metabolic control in type 1 diabetes but has so far failed to prevent or halt β-cell autoimmunity as an immune modulatory reagent.

Cholecalciferol plus calcium suppresses abnormal PBMC reactivity in patients with multiple sclerosis

CONTEXT

The active metabolite of vitamin D, 1,25-dihydroxyvitamin D [1,25(OH)(2)D], is a potent modulator of immune cells in vitro.

OBJECTIVE

Our objective was to determine whether the sun-dependent nutrient, cholecalciferol, can alter disease-associated cellular immune abnormalities in patients with multiple sclerosis (MS).

DESIGN

This was an open-label, 12-month, randomized controlled trial.

SETTING

Patients with MS were recruited from the MS Clinic at St. Michael's Hospital, Toronto.

PATIENTS

Forty-nine patients were matched (for age, sex, disease duration, disease-modifying drug, and disability) and enrolled (treated n = 25; control n = 24). Four patients were lost to follow-up (n = 2 from each group).

INTERVENTION

Treated patients received increasing doses of cholecalciferol (4,000-40,000 IU/d) plus calcium (1200 mg/d), followed by equilibration to a moderate, physiological intake (10,000 IU/d). Control patients did not receive supplements.

MAIN OUTCOME MEASURES

At enrollment and at 12 months, peripheral blood mononuclear cell (PBMC) proliferative responses to disease-associated, MS-relevant, and control antigens were measured, along with selected serum biochemical markers.

RESULTS

At 12 months, mean serum 25-hydroxyvitamin D [25(OH)D] concentrations were 83 ± 35 nmol/liter and 179 ± 76 nmol/liter in control and treated participants, respectively (paired t, P < 0.001). Serum 1,25(OH)(2)D did not differ between baseline and 1 yr. In treated patients, 12-month PBMC proliferative responses to neuron antigens myelin basic protein and exon-2 were suppressed (P = 0.002). In controls, there were no significant changes in disease-associated PBMC responsiveness. There were no significant differences between groups in levels of selected biomarkers.

INTERPRETATION

MS-associated, abnormal T cell reactivities were suppressed in vivo by cholecalciferol at serum 25(OH)D concentrations higher than 100 nmol/liter.

Increased T cell proliferative responses to islet antigens identify clinical responders to anti-CD20 monoclonal antibody (rituximab) therapy in type 1 diabetes

Type 1 diabetes mellitus is believed to be due to the autoimmune destruction of β-cells by T lymphocytes, but a single course of rituximab, a monoclonal anti-CD20 B lymphocyte Ab, can attenuate C-peptide loss over the first year of disease. The effects of B cell depletion on disease-associated T cell responses have not been studied. We compare changes in lymphocyte subsets, T cell proliferative responses to disease-associated target Ags, and C-peptide levels of participants who did (responders) or did not (nonresponders) show signs of β-cell preservation 1 y after rituximab therapy in a placebo-controlled TrialNet trial. Rituximab decreased B lymphocyte levels after four weekly doses of mAb. T cell proliferative responses to diabetes-associated Ags were present at baseline in 75% of anti-CD20- and 82% of placebo-treated subjects and were not different over time. However, in rituximab-treated subjects with significant C-peptide preservation at 6 mo (58%), the proliferative responses to diabetes-associated total (p = 0.032), islet-specific (p = 0.048), and neuronal autoantigens (p = 0.005) increased over the 12-mo observation period. This relationship was not seen in placebo-treated patients. We conclude that in patients with type 1 diabetes mellitus, anti-B cell mAb causes increased proliferative responses to diabetes Ags and attenuated β-cell loss. The way in which these responses affect the disease course remains unknown.

IL-13Rα1 expression on β-cell-specific T cells in NOD mice

OBJECTIVE

Immunotherapy using peptides from the β-cell antigen GAD65 can preserve glucose homeostasis in diabetes-prone NOD mice; however, the precise mechanisms that arrest islet-reactive T cells remain unresolved. Our previous work revealed that a dominant GAD65 epitope contained two overlapping I-A(g7)-restricted determinants, 524-538 and 530-543, with the former associated with amelioration of hyperglycemia. Here, we sought to discover whether p524-538-specific T cells could directly regulate islet-reactive T cells.

RESEARCH DESIGN AND METHODS

Prediabetic NOD mice were used to determine the relationship between peptide p524-538-induced interleukin (IL)-13 and regulation of islet autoimmunity. Pancreatic lymph node (PLN) cells from mice at distinct stages of islet inflammation, peri-insulitis versus invasive insulitis, were harvested to establish the expression pattern of IL-13 receptor α1 (IL-13Rα1) on islet-associated T cells.

RESULTS

Peptide p524-538 preferentially induced IL-13-producing T cells that antagonized the release of γ-interferon by spontaneously arising GAD65 autoimmunity, and recombinant human IL-13 inhibited proliferation of islet-reactive clonotypic T cells. A subset of CD4(+) T cells in NOD and NOD.BDC2.5 T cell receptor transgenic mice expressed functional IL-13Rα1, which induced phosphorylation of signal transducer and activator of transcription 6 in the presence of cognate cytokine. Notably, the number of IL-13Rα1(+) T cells was heightened in the PLN of young NOD mice when compared with older female counterparts with advanced insulitis. Immunization with p524-538 preserved IL-13Rα1 expression on PLN T cells.

CONCLUSIONS

IL-13 may be important for regulating autoimmunity in the early stages of insulitis, and the loss of IL-13Rα1 on islet-reactive T cells may be a biomarker for fading regional immune regulation and progression to overt diabetes.

Investigating the role of T-cell avidity and killing efficacy in relation to type 1 diabetes prediction

During the progression of the clinical onset of Type 1 Diabetes (T1D), high-risk individuals exhibit multiple islet autoantibodies and high-avidity T cells which progressively destroy beta cells causing overt T1D. In particular, novel autoantibodies, such as those against IA-2 epitopes (aa1-577), had a predictive rate of 100% in a 10-year follow up (rapid progressors), unlike conventional autoantibodies that required 15 years of follow up for a 74% predictive rate (slow progressors). The discrepancy between these two groups is thought to be associated with T-cell avidity, including CD8 and/or CD4 T cells. For this purpose, we build a series of mathematical models incorporating first one clone then multiple clones of islet-specific and pathogenic CD8 and/or CD4 T cells, together with B lymphocytes, to investigate the interaction of T-cell avidity with autoantibodies in predicting disease onset. These models are instrumental in examining several experimental observations associated with T-cell avidity, including the phenomenon of avidity maturation (increased average T-cell avidity over time), based on intra- and cross-clonal competition between T cells in high-risk human subjects. The model shows that the level and persistence of autoantibodies depends not only on the avidity of T cells, but also on the killing efficacy of these cells. Quantification and modeling of autoreactive T-cell avidities can thus determine the level of risk associated with each type of autoantibodies and the timing of T1D disease onset in individuals that have been tested positive for these autoantibodies. Such studies may lead to early diagnosis of the disease in high-risk individuals and thus potentially serve as a means of staging patients for clinical trials of preventive or interventional therapies far before disease onset.

Parenteral insulin suppresses T cell proliferation to islet antigens

The diabetes prevention trial-type 1 (DPT-1) tested whether a combination of SQ and IV insulin therapy would delay the onset of disease in individuals at high risk of progression. We investigated whether this regimen altered T cell responses to human islet proteins using cellular immunoblotting. Among the 10 treated and 7 control subjects studied, we found that there was a significant effect of treatment on cellular immunoblotting responses. We conclude that parenteral insulin may suppress proliferation to islet antigens in individuals at risk for diabetes, but this effect may be transient. Further study is needed to determine whether a therapy that results in sustained suppression of T cell proliferation could yield a measurable clinical benefit.

The potential of multimer technologies in type 1 diabetes prediction strategies

Type 1 diabetes is an autoimmune disease which occurs in (human leukocyte antigen) genetically predisposed individuals as a consequence of the organ-specific immune destruction of the insulin-producing β cells in the islets of Langherans within the pancreas. Type 1 diabetes is the result of a breakdown in immune regulation that leads to expansion of autoreactive CD4+ and CD8+ T cells, autoantibody-producing B lymphocytes and activation of the innate immune system. Islet-related autoantibodies revealed themselves to be good predictors of future onset of the disease, although they are not directly pathogenetic; T cells instead play a dominant role in disease initiation and progression. In this review, we first discuss the approaches that several laboratories attempted to measure human islet autoantigen-specific T-cell function in type 1 diabetes. T-cell assays could be used in combination with standardized autoantibody screenings to improve predictive strategies. They could also help to monitor in long-term follow-up the efficacy of tolerogenic immunotherapeutic strategies when established at the onset of the disease, and help to predict the recurrence of disease. Although some recent developments based on enzyme-linked immunosorbent spot and immunoblotting techniques have been able to distinguish with good sensitivity and specificity patients from controls, T-cell results, as revealed by international workshops, were indeed largely inconclusive. Nowadays, novel technologies have been exploited that could contribute to answering the tantalizing question of identifying autoreactive T cells. We particularly focus on and discuss MHC multimer tools and emphasize the advantages they can offer but also their weaknesses when used in combination with other T-cell assays. Copyright © 2011 John Wiley & Sons, Ltd.

Identification of autoantibody-negative autoimmune type 2 diabetic patients

OBJECTIVE

Islet autoimmunity has long been recognized in the pathogenesis of type 1 diabetes and is becoming increasingly acknowledged as a component in the pathogenesis of type 2 diabetes. Islet reactive T cells and autoantibodies have been demonstrated in type 1 diabetes, whereas islet autoimmunity in type 2 diabetes has been limited to islet autoantibodies. In this study, we investigated whether islet reactive T cells might also be present in type 2 diabetic patients and how islet reactive T cells correlate with β-cell function.

RESEARCH DESIGN AND METHODS

Adult phenotypic type 2 diabetic patients (n = 36) were screened for islet reactive T-cell responses using cellular immunoblotting and five islet autoantibodies (islet cell antibody, GADA, insulin autoantibody, insulinoma-associated protein-2 autoantibody, and zinc transporter autoantibody).

RESULTS

We identified four subgroups of adult phenotypic type 2 diabetic patients based on their immunological status (Ab(-)T(-), Ab(+)T(-), Ab(-)T(+), and Ab(+)T(+)). The Ab(-)T(+) type 2 diabetic patients demonstrated T-cell responses similar to those of the Ab(+)T(+) type 2 diabetic patients. Data were adjusted for BMI, insulin resistance, and duration of diabetes. Significant differences (P < 0.02) were observed among groups for fasting and glucagon-stimulated C-peptide responses. T-cell responses to islet proteins were also demonstrated to fluctuate less than autoantibody responses.

CONCLUSIONS

We have identified a group of adult autoimmune phenotypic type 2 diabetic patients who are Ab(-)T(+) and thus would not be detected using autoantibody testing alone. We conclude that islet autoimmunity may be more prevalent in adult phenotypic type 2 diabetic patients than previously estimated.

Type 1 Diabetes: Etiology, Immunology, and Therapeutic Strategies

Type 1 diabetes (T1D) is a chronic autoimmune disease in which destruction or damaging of the beta-cells in the islets of Langerhans results in insulin deficiency and hyperglycemia. We only know for sure that autoimmunity is the predominant effector mechanism of T1D, but may not be its primary cause. T1D precipitates in genetically susceptible individuals, very likely as a result of an environmental trigger. Current genetic data point towards the following genes as susceptibility genes: HLA, insulin, PTPN22, IL2Ra, and CTLA4. Epidemiological and other studies suggest a triggering role for enteroviruses, while other microorganisms might provide protection. Efficacious prevention of T1D will require detection of the earliest events in the process. So far, autoantibodies are most widely used as serum biomarker, but T-cell readouts and metabolome studies might strengthen and bring forward diagnosis. Current preventive clinical trials mostly focus on environmental triggers. Therapeutic trials test the efficacy of antigen-specific and antigen-nonspecific immune interventions, but also include restoration of the affected beta-cell mass by islet transplantation, neogenesis and regeneration, and combinations thereof. In this comprehensive review, we explain the genetic, environmental, and immunological data underlying the prevention and intervention strategies to constrain T1D.

The Immune Tolerance Network at 10 years: tolerance research at the bedside

Immune tolerance-inducing therapies reprogramme immune cells to eliminate pathogenic immune responses while preserving protective immunity. The Immune Tolerance Network (ITN), sponsored by the US National Institutes of Health, was established in 1999 to evaluate new tolerance-inducing therapies and carry out mechanistic studies using a unique interactive approach in partnership with industry, academia and foundations. Ten years later, the ITN has carried out approximately 36 clinical trials and tolerance studies examining innovative tolerogenic approaches in the settings of allergy, autoimmune diseases and organ transplantation. ITN investigators have published more than 80 original research papers based on this work. This Timeline article summarizes the progress and challenges of clinical research in the ITN.

Changes in GAD65Ab-specific antiidiotypic antibody levels correlate with changes in C-peptide levels and progression to islet cell autoimmunity

CONTEXT

The previously reported absence of 65-kDa glutamate decarboxylase antibody (GAD65Ab)-specific antiidiotypic antibodies (anti-Id) in type 1 diabetes (T1D) patients at clinical onset could be due to an inability to mount an antibody response to GAD65Ab or a longitudinal decline in anti-Id levels.

OBJECTIVE AND DESIGN

We investigated anti-Id levels in longitudinal samples obtained from T1D patients (n = 41) (clinical diagnosis - 12 months), and latent autoimmune diabetes in adults (LADA) patients (n = 32) who received alum-formulated human recombinant GAD65 (baseline - 12 months). We also determined anti-Id levels in a small cohort of Type 2 diabetes patients during their development of autoimmune T cell responses.

RESULTS

At clinical onset T1D patients presented no or low anti-Id levels. However, 22/41 T1D patients showed ≥50% increase in GAD65Ab-specific anti-Id levels during follow-up; peaking at 3 (n = 1), 6 (n = 10), 9 (n = 10), or 12 (n = 1) months. Increasing anti-Id levels marked patients who experienced a temporary increase in C-peptide levels. Anti-Id levels correlated significantly with glycated hemoglobin and C-peptide levels at 6 and 9 months (P values ranged from <0.001 to <0.05). In LADA patients receiving placebo, anti-Id levels declined in seven of nine patients, whereas four of five patients receiving 20 μg alum-formulated human recombinant GAD65 showed increasing anti-Id levels. Changes in anti-Id and C-peptide levels closely correlated (P < 0.0001). The significant decline in anti-Id levels (P = 0.03) in T2D patients developing T cell autoimmune responses supports our hypothesis that declining anti-Id levels are associated with developing islet autoimmunity.

CONCLUSIONS

The close association between GAD65Ab-specific anti-Id levels and β-cell function may provide a novel marker for the progression of autoimmune diabetes.

Current approaches to measuring human islet-antigen specific T cell function in type 1 diabetes

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.

Simultaneous detection of circulating autoreactive CD8+ T-cells specific for different islet cell-associated epitopes using combinatorial MHC multimers

OBJECTIVE

Type 1 diabetes results from selective T-cell-mediated destruction of the insulin-producing beta-cells in the pancreas. In this process, islet epitope-specific CD8(+) T-cells play a pivotal role. Thus, monitoring of multiple islet-specific CD8(+) T-cells may prove to be valuable for measuring disease activity, progression, and intervention. Yet, conventional detection techniques (ELISPOT and HLA tetramers) require many cells and are relatively insensitive.

RESEARCH DESIGN AND METHODS

Here, we used a combinatorial quantum dot major histocompatibility complex multimer technique to simultaneously monitor the presence of HLA-A2 restricted insulin B(10-18), prepro-insulin (PPI)(15-24), islet antigen (IA)-2(797-805), GAD65(114-123), islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP)(265-273), and prepro islet amyloid polypeptide (ppIAPP)(5-13)-specific CD8(+) T-cells in recent-onset diabetic patients, their siblings, healthy control subjects, and islet cell transplantation recipients.

RESULTS

Using this kit, islet autoreactive CD8(+) T-cells recognizing insulin B(10-18), IA-2(797-805), and IGRP(265-273) were shown to be frequently detectable in recent-onset diabetic patients but rarely in healthy control subjects; PPI(15-24) proved to be the most sensitive epitope. Applying the "Diab-Q-kit" to samples of islet cell transplantation recipients allowed detection of changes of autoreactive T-cell frequencies against multiple islet cell-derived epitopes that were associated with disease activity and correlated with clinical outcome.

CONCLUSIONS

A kit was developed that allows simultaneous detection of CD8(+) T-cells reactive to multiple HLA-A2-restricted beta-cell epitopes requiring limited amounts of blood, without a need for in vitro culture, that is applicable on stored blood samples.

Recent insights into CD4+ T-cell specificity and function in type 1 diabetes

Type 1 diabetes (T1D) is caused by T-cell-mediated destruction of the insulin-producing beta-cells in the pancreas. Genetic and immunological evidence from humans and mouse models indicates that CD4(+) T cells play a crucial role in the development and prevention of T1D. The dichotomy between CD4(+) T regulatory and effector T cells has encouraged research into the role of these cell subsets in T1D. New antigens and epitopes recognized by CD4(+) T cells in affected individuals have been identified. Growing knowledge of T-cell specificity and function is helping to develop new assays for analyzing islet antigen-specific CD4(+) T cells from human blood. Here we discuss, with particular reference to human studies, advances in our understanding of CD4(+) T-cell responses in T1D.

Immunotherapy of type 1 diabetes: where are we and where should we be going?

Type 1 diabetes (T1D) is a chronic autoimmune disorder characterized by destruction of insulin-producing pancreatic beta cells. Many broad-based immunosuppressive and antigen-specific immunoregulatory therapies have been and are currently being evaluated for their utility in the prevention and treatment of T1D. Looking forward, this review discusses the potential therapeutic use of antigen-specific tolerance strategies, including tolerance induced by "tolerogenic" antigen-presenting cells pulsed with diabetogenic antigens and transfer of induced or expanded regulatory T cells, which have demonstrated efficacy in nonobese diabetic (NOD) mice. Depending on the time of therapeutic intervention in the T1D disease process, antigen-specific immunoregulatory strategies may be employed as monotherapies, or in combination with short-term tolerance-promoting immunoregulatory drugs and/or drugs promoting differentiation of insulin-producing beta cells from endogenous progenitors.

Monitoring of antigen-specific CD8 T cells in patients with type 1 diabetes treated with antiCD3 monoclonal antibodies

The way in which anti-CD3 monoclonal antibodies (mAbs) modify human immune responses in type 1 diabetes (T1DM) is not known. We prepared a panel of Class I HLA-A2.1 tetramers with peptides from diabetes-associated antigens and studied the frequency and phenotype of the cells in patients with T1DM and blood donors and in patients treated with anti-CD3 mAb (Teplizumab). More patients with T1DM showed positive staining for at least 1 tetramer using frozen and fresh samples (p<0.05). Three months following treatment with anti-CD3 mAb, the proportion of GAD65- and InsB-peptide reactive CD8+ T cells increased (p<0.05). The phenotype of these cells was modulated from naïve to effector memoryRA+. We concludethat Class I MHC tetramers can identify antigen specific CD8+ T cells in patients with T1DM. The frequency of certain specificities increases after treatment with anti-CD3 mAb. Their modulated phenotype may have functional consequences for their pathogenicity.