The relationship between humoral and cellular immunity to IA-2 in IDDM

Nivolumab-induced diabetes mellitus-a case report with literature review of the treatment options

Background

Immune checkpoint inhibitor (ICI) treatment has become important for treating various cancer types, including metastatic renal cell carcinoma. However, ICI treatment can lead to endocrine immune-related adverse events (irAEs) by overstimulating the patient's immune system. Here, we report a rare case of a new onset of diabetes mellitus (DM), caused by nivolumab, and we discuss the feasible treatment options with a focus on TNF antagonism.

Case presentation

A 50-year-old man was diagnosed with metastatic renal cell carcinoma. Due to systemic progression, a combined immunotherapy with ipilimumab and nivolumab was initiated, according to the current study protocol (SAKK 07/17). The administration of ipilimumab was stopped after 10 months, due to partial response as seen in the computer tomography (CT), and nivolumab was continued as monotherapy. Fourteen months after the start of the treatment, the patient was admitted to the emergency department with lethargy, vomiting, blurred vision, polydipsia, and polyuria. The diagnosis of DM with diabetic ketoacidosis was established, although autoantibodies to β-cells were not detectable. Intravenous fluids and insulin infusion treatment were immediately initiated with switching to a subcutaneous administration after 1 day. In addition, the patient received an infusion of the TNF inhibitor infliximab 4 days and 2 weeks after the initial diagnosis of DM. However, the C-peptide values remained low, indicating a sustained insulin deficiency, and the patient remained on basal bolus insulin treatment. Two months later, nivolumab treatment was restarted without destabilization of the diabetic situation.

Conclusions

In contrast to the treatment of other irAEs, the administration of corticosteroids is not recommended in ICI-induced DM. The options for further treatment are mainly based on the low numbers of case series and case reports. In our case, the administration of infliximab-in an attempt to salvage the function of β-cells-was not successful, and this is in contrast to some previous reports. This apparent discrepancy may be explained by the absence of insulin resistance in our case. There is so far no evidence for immunosuppressive treatment in this situation. Prompt recognition and immediate start of insulin treatment are most important in its management.

Diabetes type 1: Can it be treated as an autoimmune disorder?

Type 1 Diabetes Mellitus (T1DM) is characterized by progressive autoimmune-mediated destruction of the pancreatic beta-cells leading to insulin deficiency and hyperglycemia. It is associated with significant treatment burden and necessitates life-long insulin therapy. The role of immunotherapy in the prevention and management of T1DM is an evolving area of interest which has the potential to alter the natural history of this disease.In this review, we give insight into recent clinical trials related to the use of immunotherapeutic approaches for T1DM, such as proinflammatory cytokine inhibition, cell-depletion and cell-therapy approaches, autoantigen-specific treatments and stem cell therapies. We highlight the timing of intervention, aspects of therapy including adverse effects and the emergence of a novel lymphocyte crucial in T1DM autoimmunity. We also discuss the role of cardiac autoimmunity and its link to excess CVD risk in T1DM.We conclude that significant advances have been made in development of immunotherapeutic targets and agents for the treatment and prevention of T1DM. These immune-based therapies promise preservation of beta-cells and decreasing insulin dependency. In their current state, immunotherapeutic approaches cannot yet halt the progression from a preclinical state to overt T1DM nor can they replace standard insulin therapy in existing T1DM. It remains to be seen whether immunotherapy will ultimately play a key role in the prevention of progression to overt T1DM and whether it may find a place in our therapeutic armamentarium to improve clinical outcomes and quality of life in established T1DM.

Prevalence of autoantibodies in type 1 diabetes mellitus pediatrics in Mazandaran, North of Iran

Objectives Type 1 diabetes is an autoimmune disease. Its most important immunologic markers are pancreatic beta-cell autoantibodies. This study aimed to determine diabetes mellitus antibodies frequency among children and adolescents with type 1 diabetes. Methods This descriptive study evaluated the frequency of four diabetes autoantibodies (glutamic acid decarboxylase 65 autoantibodies [GADA], islet cell autoantibodies [ICA], insulin autoantibodies [IAA], tyrosine phosphatase-like insulinoma antigen-2 antibodies [IA-2A]) and their serum level in children and adolescents diagnosed with type 1 diabetes mellitus at the diabetes department of Bou-Ali-Sina Hospital and Baghban Clinic, Sari, Iran, from March 2012 to March 2018. The relationship between the level of different antibodies and age, gender, and diabetes duration were determined. A two-sided p value less than 0.05 indicated statistical significance. Results One hundred forty-two eligible patient records were screened. The average age at diabetes diagnosis was 4.2 ± 4.4 years. The median duration of diabetes was 34.0 (12.7-69.7) months. 53.5% of patients were female, and 81.7% of them had at least one positive autoantibody, and ICA in 66.2%, GADA in 56.3%, IA-2A in 40.1%, and IAA in 21.8% were positive. The type of the autoantibodies and their serum level was similar between females and males but there was a higher rate of positive autoantibodies in females. The level of IA-2A and ICA were in positive and weak correlation with age at diagnosis. Conclusions More than 80% of pediatric and adolescent patients with type 1 diabetes were autoantibody-positive. ICA and GADA were the most frequently detected autoantibodies. The presence of antibodies was significantly higher in females.

Checkpoint Inhibitor-Associated Autoimmune Diabetes Is Distinct From Type 1 Diabetes

CONTEXT

Checkpoint inhibitor-associated autoimmune diabetes mellitus (CIADM) is a rare illness, and little is known about its incidence, clinical features, or pathogenesis.

CASE SERIES DESCRIPTION

Consecutive patients from a single quaternary melanoma center who developed new-onset insulin-requiring diabetes after commencing anti-programmed cell death-1 (PD-1) immunotherapy were studied to describe CIADM characteristics. Ten (1.9%) of 538 patients with metastatic melanoma treated with anti-PD-1-based immunotherapy from March 2015 to March 2018 developed CIADM. Nine patients had no history of diabetes, and one had pre-existing type 2 diabetes mellitus. Median time from immunotherapy start to CIADM diagnosis was 25 weeks [interquartile range (IQR), 17.5 to 34.5 weeks]. All patients had normal serum C-peptide shortly before CIADM onset and an inappropriately low level when measured soon after. At CIADM diagnosis, median hemoglobin A1c was 7.6% (IQR, 7.15% to 9.75%), median glucose level was 32.5 mmol/L (IQR, 21.6 to 36.7 mmol/L), and median C-peptide concentration was 0.35 nmol/L (IQR, 0.10 to 0.49 mmol/L). Type 1 diabetes (T1D)-associated autoantibodies (DAAs) were present in two patients (both of whom had anti-glutamic acid decarboxylase antibody); all were negative for insulin-associated protein 2, insulin, and ZnT8. Three patients were heterozygous for an HLA class II T1D-risk haplotype; two additional patients also carried protective haplotypes for T1D. All patients continued immunotherapy; eight (80%) had complete or partial oncological response, and all patients required ongoing insulin therapy.

CONCLUSION

CIADM is characterized by sudden permanent β-cell failure occurring after immunotherapy. It is distinct from T1D, usually lacks DAA or T1D-associated HLA-risk haplotypes, and is associated with difficult glycemic control from the onset. As such, CIADM represents a new model of auto-inflammatory β-cell failure.

On type 1 diabetes mellitus pathogenesis

Type 1 diabetes mellitus (T1DM) results from the autoimmune destruction of β cells of the endocrine pancreas. Pathogenesis of T1DM is different from that of type 2 diabetes mellitus, where both insulin resistance and reduced secretion of insulin by the β cells play a synergistic role. We will present genetic, environmental and immunologic factors that destroy β cells of the endocrine pancreas and lead to insulin deficiency. The process of autoimmune destruction takes place in genetically susceptible individuals under the triggering effect of one or more environmental factors and usually progresses over a period of many months to years, during which period patients are asymptomatic and euglycemic, but positive for relevant autoantibodies. Symptomatic hyperglycemia and frank diabetes occur after a long latency period, which reflects the large percentage of β cells that need to be destroyed before overt diabetes become evident.

Immune response after autologous hematopoietic stem cell transplantation in type 1 diabetes mellitus

Background

This study explored the details of the immune response after autologous hematopoietic stem cell transplantation (AHSCT) treatment in type 1 diabetes mellitus.

Methods

Peripheral blood mononuclear cells (PBMCs) from 18 patients with type 1 diabetes mellitus were taken at baseline and 12 months after AHSCT or insulin-only therapy. The lymphocyte proliferation, mRNA expression and secretion of pro-inflammatory and anti-inflammatory cytokines belonging to T-helper type 1 (Th1), T-helper type 17 (Th17) and regulatory T (Treg) cells in PBMC culture supernatants were assessed.

Results

Compared with patients receiving insulin-only treatment, the patients receiving AHSCT treatment showed better residual C-peptide secretion, lower anti-GAD titers and less exogenous insulin dosages after 12 months of follow-up. AHSCT treatment was associated with significantly reduced Th1 and Th17 cell proportions as well as decreased IFN-γ, IL-2, IL-12p40 and IL-17A levels in the PBMC culture supernatants (all P < 0.05). Although there was no significant Treg cell expansion after AHSCT treatment, we observed increased IL-10, TGF-β and Foxp3 mRNA expression and increased TGF-β levels. However, we found no significant changes in the T-cell subpopulations after insulin treatment, except for higher IL-12p40 mRNA expression and a lower proportion of Treg cells.

Conclusions

AHSCT treatment was associated with decreased expansion and function of Th1 and Th17 cells, which may explain the better therapeutic effect of AHSCT compared with the traditional intensive insulin therapy.

Trial registration

Clinicaltrials.gov NCT00807651. Registered 18 December 2008.

Psychological stress in children may alter the immune response

Psychological stress is a public health issue even in children and has been associated with a number of immunological diseases. The aim of this study was to examine the relationship between psychological stress and immune response in healthy children, with special focus on autoimmunity. In this study, psychological stress was based on a composite measure of stress in the family across the domains: 1) serious life events, 2) parenting stress, 3) lack of social support, and 4) parental worries. PBMCs, collected from 5-y-old high-stressed children (n = 26) and from 5-y-old children without high stress within the family (n = 52), from the All Babies In Southeast Sweden cohort, were stimulated with Ags (tetanus toxoid and β-lactoglobulin) and diabetes-related autoantigens (glutamic acid decarboxylase 65, insulin, heat shock protein 60, and tyrosine phosphatase). Immune markers (cytokines and chemokines), clinical parameters (C-peptide, proinsulin, glucose), and cortisol, as an indicator of stress, were analyzed. Children from families with high psychological stress showed a low spontaneous immune activity (IL-5, IL-10, IL-13, IL-17, CCL2, CCL3, and CXCL10; p < 0.01) but an increased immune response to tetanus toxoid, β-lactoglobulin, and the autoantigens glutamic acid decarboxylase 65, heat shock protein 60, and tyrosine phosphatase (IL-5, IL-6, IL-10, IL-13, IL-17, IFN-γ, TNF-α, CCL2, CCL3, and CXCL10; p < 0.05). Children within the high-stress group showed high level of cortisol, but low level of C-peptide, compared with the control group (p < 0.05). This supports the hypothesis that psychological stress may contribute to an imbalance in the immune response but also to a pathological effect on the insulin-producing β cells.

Role of immune system modulation in prevention of type 1 diabetes mellitus

An increased incidence of Type 1 diabetes mellitus (T1DM) is expected worldwide. Eventually, T1DM is fatal unless treated with insulin. The expansion of interventions to prevent diabetes and the use of alternative treatments to insulin is a dream to be fulfilled. The pathophysiology in T1DM is basically a destruction of beta cells in the pancreas, regardless of which risk factors or causative entities have been present. Individual risk factors can have separate patho-physiological processes to, in turn, cause this beta cell destruction. Currently, autoimmunity is considered the major factor in the pathophysiology of T1DM. In a genetically susceptible individual, viral infection may stimulate the production of antibodies against a viral protein that trigger an autoimmune response against antigenically similar beta cell molecules. Many components of the immune system have been implicated in autoimmunity leading to β-cell destruction, including cytotoxic and helper T-cells, B-cells, macrophages, and dendritic cells. The inflammatory process in early diabetes is thought to be initiated and propagated by the effect of Th1-secreted cytokines (e.g. g interferon) and suppressed by Th2-secreted antiinflammatory cytokines (interleukins). Structure and function of β-cell may be modulated by using Th1/Th2-secreted cytokines. Several experimental and clinical trials of applying GAD65, Hsp60, peptide-MHC, pepetide-277 immunization, anti-CD3 infusion, and interleukins to modulate immune response in T1DM were done. Applying such trials in patients with prediabetes, will most likely be the future key in preventing Type 1 autoimmune diabetes.

Guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus

BACKGROUND

Multiple laboratory tests are used to diagnose and manage patients with diabetes mellitus. The quality of the scientific evidence supporting the use of these tests varies substantially.

APPROACH

An expert committee compiled evidence-based recommendations for the use of laboratory testing for patients with diabetes. A new system was developed to grade the overall quality of the evidence and the strength of the recommendations. Draft guidelines were posted on the Internet and presented at the 2007 Arnold O. Beckman Conference. The document was modified in response to oral and written comments, and a revised draft was posted in 2010 and again modified in response to written comments. The National Academy of Clinical Biochemistry and the Evidence-Based Laboratory Medicine Committee of the American Association for Clinical Chemistry jointly reviewed the guidelines, which were accepted after revisions by the Professional Practice Committee and subsequently approved by the Executive Committee of the American Diabetes Association.

CONTENT

In addition to long-standing criteria based on measurement of plasma glucose, diabetes can be diagnosed by demonstrating increased blood hemoglobin A(1c) (HbA(1c)) concentrations. Monitoring of glycemic control is performed by self-monitoring of plasma or blood glucose with meters and by laboratory analysis of HbA(1c). The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of autoantibodies, urine albumin, insulin, proinsulin, C-peptide, and other analytes are addressed.

SUMMARY

The guidelines provide specific recommendations that are based on published data or derived from expert consensus. Several analytes have minimal clinical value at present, and their measurement is not recommended.

Guidelines and recommendations for laboratory analysis in the diagnosis and management of diabetes mellitus

BACKGROUND

Multiple laboratory tests are used to diagnose and manage patients with diabetes mellitus. The quality of the scientific evidence supporting the use of these tests varies substantially.

APPROACH

An expert committee compiled evidence-based recommendations for the use of laboratory testing for patients with diabetes. A new system was developed to grade the overall quality of the evidence and the strength of the recommendations. Draft guidelines were posted on the Internet and presented at the 2007 Arnold O. Beckman Conference. The document was modified in response to oral and written comments, and a revised draft was posted in 2010 and again modified in response to written comments. The National Academy of Clinical Biochemistry and the Evidence Based Laboratory Medicine Committee of the AACC jointly reviewed the guidelines, which were accepted after revisions by the Professional Practice Committee and subsequently approved by the Executive Committee of the American Diabetes Association.

CONTENT

In addition to long-standing criteria based on measurement of plasma glucose, diabetes can be diagnosed by demonstrating increased blood hemoglobin A(1c) (Hb A(1c)) concentrations. Monitoring of glycemic control is performed by self-monitoring of plasma or blood glucose with meters and by laboratory analysis of Hb A(1c). The potential roles of noninvasive glucose monitoring, genetic testing, and measurement of autoantibodies, urine albumin, insulin, proinsulin, C-peptide, and other analytes are addressed.

SUMMARY

The guidelines provide specific recommendations that are based on published data or derived from expert consensus. Several analytes have minimal clinical value at present, and their measurement is not recommended.

Switch from a dominant Th1-associated immune profile during the pre-diabetic phase in favour of a temporary increase of a Th3-associated and inflammatory immune profile at the onset of type 1 diabetes

BACKGROUND

Type 1 diabetes (T1D) is an autoimmune disease dominated by loss of self-tolerance resulting in depletion of the beta-cells. This study aims to confirm previous observations of a dominant T-helper (Th)1-like profile during the period close to onset of disease. Further, to follow the immune response from onset to 2 years duration, the study focused on spontaneous as well as autoantigen-induced immune profile.

METHODS

Peripheral blood mononuclear cells were collected 4 days and 1 and 2 years after diagnosis of T1D children, from healthy children carrying the human leukocyte antigen-risk genes and from high-risk children (ICA > or = 20 IJDF units). Peripheral blood mononuclear cells were stimulated with glutamic acid decarboxylase (GAD(65)) and phytohaemagglutinin (PHA). Cytokines and chemokines were detected in cell-culture supernatants by protein microarray (naive T-cells; interleukin (IL)-7, Th1; interferon-gamma, tumour necrosis factor-beta, Th2; IL-5, Th3; transforming growth factor-beta, T-regulatory cell type 1; IL-10 and inflammatory cytokines; tumour necrosis factor-alpha, IL-6 and chemokines; monocyte chemoattractant protein-1, monokine upregulated by IFN-gamma) in relation to clinical outcome (C-peptide).

RESULTS

High-risk children showed a dominant Th1-associated profile with high spontaneous and GAD(65)-induced secretion. The mitogen PHA instead induced a Th2-associated response exclusively in high-risk children. In contrast, newly diagnosed T1D children showed a pronounced Th3-associated cytokine profile as well as a burst of inflammatory cytokines and chemokines secreted both spontaneously and by GAD(65) and PHA stimulation. The immune response to GAD(65) and PHA, however, diminished with duration of disease.

CONCLUSION

A dominant Th1-associated immune profile was observed during the pre-diabetic phase. This Th1 dominance, however, diminished in favour of a temporary increase in a Th3-associated and inflammatory immune profile at the onset of disease.

Identification of tyrosine phosphatase 2(256-760) construct as a new, sensitive marker for the detection of islet autoimmunity in type 2 diabetic patients: the non-insulin requiring autoimmune diabetes (NIRAD) study 2

OBJECTIVE

The presence of autoantibodies to islet antigens GAD and/or tyrosine phosphatase 2 (IA-2) in type 2 diabetic patients (latent autoimmune diabetes in adults [LADA]) identifies subjects at high risk to develop insulin dependency. The aim of this study was to dissect humoral anti-IA-2 immune response in Caucasian LADA patients, identifying the most sensitive construct to evaluate IA-2 immunoreactivity and comparing LADA IA-2 epitope specificities to those found in type 1 diabetes.

RESEARCH DESIGN AND METHODS

We analyzed 177 LADA and 978 type 2 diabetic patients with different disease duration, collected in a nationwide Italian survey, the Non-Insulin Requiring Autoimmune Diabetes (NIRAD) study aimed at assessing prevalence and characteristics of autoimmune diabetes in type 2 diabetic patients and 106 newly diagnosed type 1 diabetic patients (53 children, 53 adults). By radioimmunoassay, we analyzed humoral immunoreactivity to seven IA-2 constructs: IA-2(PTP (687-979)), IA-2((761-964)), IA-2((256-760)), IA-2(JM (601-630)), IA-2(IC (605-979)), IA-2(BDC (256-556:630-979)), and IA-2(FL (1-979)).

RESULTS

IA-2((256-760)) fragment was identified as the marker with the highest sensitivity for detection of humoral IA-2 immunoreactivity in LADA patients, identifying IA-2 autoantibodies in approximately 30% of GAD antibody (GADA)-positive LADA patients and in 3.4% of GADA-negative type 2 diabetic patients. LADA IA-2((256-760))A positivity was associated with an increased frequency of autoimmune diabetes HLA-susceptible genotypes and with a higher risk for developing thyroid autoimmunity compared with autoantibody-negative type 2 diabetic patients. At disease diagnosis, adult-onset type 1 diabetic and LADA patients showed a lower IA-2 COOH-terminal immunoreactivity compared with childhood-onset type 1 diabetic patients.

CONCLUSIONS

IA-2 immunoreactivity in LADA patients has thus far been underestimated, and IA-2((256-760)) autoantibody detection may represent a novel diagnostic tool for the identification of islet autoimmunity in these patients.

Combinations of common chronic paediatric diseases deviate the immune response in diverging directions

The cytokine pattern of T lymphocytes has not been characterized in children with combinations of paediatric immunological disorders. We describe cytokine secretion in children with type 1 diabetes, coeliac disease and allergy and combinations of two of these diseases after stimulation with 'disease-specific' antigens. Peripheral blood mononuclear cells (PBMC) were collected from 68 children with type 1 diabetes, allergy or coeliac disease, two of these diseases in combination or none of these diseases. Using the enzyme-linked immunospot (ELISPOT) technique, interferon (IFN)-gamma and interleukin (IL)-4 were analysed from fresh PBMC spontaneously and after in vitro stimulation with antigens associated with one or more of these diseases (insulin, gluten, birch and cat extract, beta-lactoglobulin, ovalbumin and phytohaemagglutinin) in order to divide T helper (Th)1- from Th2-like lymphocytes. Stimulation with birch and cat extract caused increased IL-4 secretion in allergic children. A low IFN-gamma response to insulin was found in type 1 diabetic children, whereas allergic children responded to insulin by increased IL-4 secretion. Children suffering from both type 1 diabetes (Th1-prone) and allergy (Th2-prone) reacted distinctly to general mitogen stimulation. Children suffering from two Th1-dominated diseases (type 1 diabetes and coeliac disease) showed hardly any response to either food or inhalation allergens. Our results indicate an important interplay between common immunological diseases in children. The combination of two Th1-deviated diseases is associated with a suppressed immune response, whereas a combination of Th1- and Th2-dominated diseases appears to increase the general immune response.

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

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.

Increased in vivo frequency of IA-2 peptide-reactive IFNgamma+/IL-4- T cells in type 1 diabetic subjects

Active T cell recognition of islet antigens has been postulated as the pathogenic mechanism in human type 1 diabetes, but evidence is scarce. If T cells are engaged, they are expected to display increased clonal size and exhibit a T helper (Th)1/Th2 differentiation state. We used a peptide library that covers tyrosine phosphatase IA-2, a target antigen expressed in pancreatic beta cells, to probe 8 diabetic patients and 5 HLA-matched controls. When tested in a high resolution IFNgamma/IL-4 double color ELISPOT assay directly ex vivo, the number of IA-2-reactive IFNgamma producing cells was 17-fold higher in patients than in controls and IL-4 producing cells were not present. An average of 9 peptides was recognized in the patients vs. one in the controls. Determinant recognition primarily involved CD4+ cells and showed high variability among the patients. Furthermore, anti-CD28 antibody signal enhances quantitative assessment of effector T cells in T1D patients. In vitro expansion with peptides and IL-2 results in detection of responding cells in the controls and loss of disease specificity of the T cell response. Together these data provide strong evidence for the active targeting of IA-2 by Th1 memory effector cells in human type 1 diabetes.

Diminished Th1-Like Response to Autoantigens in Children with a High Risk of Developing Type 1 Diabetes

The exact role of T-helper (Th) cells that precede the clinical manifestation of type 1 diabetes remains unclear. The aim of this investigation was to study the Th1- and Th2-like profile in children and adults with high risk of developing the disease. Peripheral blood mononuclear cells were collected from high-risk children and adults and from healthy individuals matched for age and gender. Using the sensitive enzyme-linked immunospot (ELISPOT) technique to divide Th1- from Th2-like lymphocytes, secretion of interferon-gamma (IFN-gamma) and interleukin-4 was analysed from lymphocytes spontaneously and after in vitro stimulation with different antigens, based on present paradigms regarding the pathogenesis of type 1 diabetes. Compared to the response observed in healthy individuals, we found that individuals with a high risk of developing type 1 diabetes, especially children, responded with less IFN-gamma secretion to the three autoantigens glutamic acid decarboxylase 65 (GAD65), insulin and tyrosinphosphatase (IA-2). Thus, a diminished Th1-like response by in vitro autoantigen stimulation was observed in especially children with a high risk of developing type 1 diabetes. Reduced Th1/Th2 response was related to signs of beta cell exhaustion.

Mapping of epitopes for autoantibodies to the type 1 diabetes autoantigen IA-2 by peptide phage display and molecular modeling: overlap of antibody and T cell determinants

IA-2 is a major target of autoimmunity in type 1 diabetes. IA-2 responsive T cells recognize determinants within regions represented by amino acids 787-817 and 841-869 of the molecule. Epitopes for IA-2 autoantibodies are largely conformational and not well defined. In this study, we used peptide phage display and homology modeling to characterize the epitope of a monoclonal IA-2 Ab (96/3) from a human type 1 diabetic patient. This Ab competes for IA-2 binding with Abs from the majority of patients with type 1 diabetes and therefore binds a region close to common autoantibody epitopes. Alignment of peptides obtained after screening phage-displayed peptide libraries with purified 96/3 identified a consensus binding sequence of Asn-x-Glu-x-x-(aromatic)-x-x-Gly. The predicted surface on a three-dimensional homology model of the tyrosine phosphatase domain of IA-2 was analyzed for clusters of Asn, Glu, and aromatic residues and amino acids contributing to the epitope investigated using site-directed mutagenesis. Mutation of each of amino acids Asn(858), Glu(836), and Trp(799) reduced 96/3 Ab binding by >45%. Mutations of these residues also inhibited binding of serum autoantibodies from IA-2 Ab-positive type 1 diabetic patients. This study identifies a region commonly recognized by autoantibodies in type 1 diabetes that overlaps with dominant T cell determinants.

T-cell epitopes in type 1 diabetes

Type 1 diabetes (TID) results from T-cell-mediated destruction of pancreatic b cells in genetically predisposed individuals. Autoreactive CD4(+) T helper cells and CD8(+) cytotoxic T lymphocytes (CTLs) recognize b-cell-derived peptides in the context of major histocompatibility complex class II and I molecules, respectively, in a process that terminates in b-cell death. Many peptide epitopes derived from b-cell proteins have been described for both humans and the nonobese diabetic (NOD) mouse, but their relative importance in disease pathogenesis is unclear. The significance of identifying key b-cell epitopes is underscored by a study showing that in the NOD mouse monitoring of a single population of b-cell-specific CTLs in the peripheral blood using a high-avidity analogue of the endogenous peptide may be used to accurately predict diabetes occurrence. Future studies focused on the discovery of immunodominant b-cell epitopes and their high-avidity analogues should have considerable implications for prediction and immunotherapy of TID.

The role of T-cells in the pathogenesis of Type 1 diabetes: from cause to cure

Type 1 diabetes mellitus results from a T-cell mediated autoimmune destruction of the pancreatic beta cells in genetically predisposed individuals. The knowledge of the immunopathogenesis has increased enormously in the last two decades. The contribution of T-cells in the pathogenesis is beyond doubt. Therapies directed against T-cells have been shown to halt the disease process and prevent recurrent beta-cell destruction after islet transplantation. Less is known about the nature and function of these T-cells, the cause of the loss of tolerance to islet autoantigens, why the immune system apparently fails to suppress autoreactivity, and whether (or which) autoantigen(s) are critically involved in the initiation or progression of the disease. The contribution of dendritic cells in directing the immune response is clear, while the contribution of B-cells and autoantibodies is subject to reconsideration. Autoreactive T-cells have proven to be valuable tools to study pathogenic or diabetes-related processes. Measuring T-cell autoreactivity has also provided critical information to determine the fate of islet allografts transplanted to Type 1 diabetic patients. Cellular autoimmunity is a difficult study subject, but it has been a worthwhile quest to unravel the role of T-cells in the pathogenesis of Type 1 diabetes. The challenge for the future is to determine which factors contribute to the loss of tolerance to beta-cell antigens, and to define what measures T-cells can provide to suppress autoreactivity, since it is becoming increasingly evident that T-cells provide a two-edged sword: some T-cells could be pathogenic, but others can regulate the disease process and thus form new targets for immunointervention.

Spontaneous peripheral T-cell responses to the IA-2beta (phogrin) autoantigen in young nonobese diabetic mice

Phogrin (IA-2beta), a major autoantigen in type 1 diabetes in man is recognized by peripheral T cells in the nonobese diabetic (NOD) mouse. CD4(+) T-cell clones derived from immunized NOD animals elicit islet destruction in a disease transfer model. Spontaneous proliferative responses to the protein and derived peptide epitopes were detected in peripheral lymph node cells (LNC) of unprimed NOD mice but not BALB/c controls as early as 4 weeks of age at a time point when insulitis in NOD animals is minimal. Responses to irradiated NOD islet cells but not irradiated NOD spleen cells were observed for both male and female NOD animals. Insulin, phogrin and phogrin-peptide 7 (aa 755-777) but not phogrin-peptide 2 (aa 640-659) or tetanus toxin peptide were recognized as antigens. Islet cell-reactive and phogrin peptide 7-specific CD4(+) T-cell lines were generated from splenocytes of unprimed 4-week-old NOD females and shown to secrete Th1-type cytokines. The results show that the phogrin molecule is targeted early in the course of disease in NOD animals at a time when circulating autoantibodies are absent and insulitis is minimal.

Guidelines and Recommendations for Laboratory Analysis in the Diagnosis and Management of Diabetes Mellitus

Background: Multiple laboratory tests are used in the diagnosis and management of patients with diabetes mellitus. The quality of the scientific evidence supporting the use of these assays varies substantially.

Approach: An expert committee drafted evidence-based recommendations for the use of laboratory analysis in patients with diabetes. An external panel of experts reviewed a draft of the guidelines, which were modified in response to the reviewers’ suggestions. A revised draft was posted on the Internet and was presented at the AACC Annual Meeting in July, 2000. The recommendations were modified again in response to oral and written comments. The guidelines were reviewed by the Professional Practice Committee of the American Diabetes Association.

Content: Measurement of plasma glucose remains the sole diagnostic criterion for diabetes. Monitoring of glycemic control is performed by the patients, who measure their own plasma or blood glucose with meters, and by laboratory analysis of glycated hemoglobin. The potential roles of noninvasive glucose monitoring, genetic testing, autoantibodies, microalbumin, proinsulin, C-peptide, and other analytes are addressed.

Summary: The guidelines provide specific recommendations based on published data or derived from expert consensus. Several analytes are of minimal clinical value at the present time, and measurement of them is not recommended.

Enterovirus infection can induce immune responses that cross-react with beta-cell autoantigen tyrosine phosphatase IA-2/IAR

Insulin-dependent (type 1) diabetes is characterized by progressive destruction of insulin-producing beta cells probably by autoreactive T lymphocytes. Viral infections, especially those caused by coxsackieviruses, are postulated to play a role in the pathogenesis of the disease in humans. One mechanism by which viral infections could initiate or accelerate diabetogenic processes is "molecular mimicry," induction of antiviral immune responses cross-reacting with epitopes in the beta-cell autoantigens. Tyrosine phosphatases (IA-2, IAR) represent a major target autoantigen in type 1 diabetes. Both humoral and cellular immune responses are directed to the carboxy-terminal (C-terminal) part of the protein. This region has a 5-amino acid sequence identity, followed by five amino acid similarity with the conservative motif in the VP1-protein of enteroviruses (PALTAVETGA/HT), which is a highly immunogenic B- and T-cell epitope in enterovirus infection-induced immune responses. This observation prompted us to investigate potential humoral cross-reactions between immune responses induced by tyrosine phosphatases and enteroviruses. The reactivities of various peptide- and virus-induced rabbit antisera clearly demonstrated that cross-reactions do exist, and in both directions. Using epitope mapping, we were able to show that several diabetes-linked epitopes in IA-2 were also recognized by CBV-4-induced antisera. Immunization of female NOD-mice with formalin-inactivated purified strain of coxsackievirus B4 (CBV-4-E2) induced an immune response that recognized the IA-2/IAR diabetogenic peptide. The results obtained with human paired sera, collected during enterovirus infection, indicated that enterovirus infection in humans may also occasionally induce a humoral response that cross-reacts with IA-2/IAR.

Molecular mimicry in type 1 diabetes mellitus revisited: T-cell clones to GAD65 peptides with sequence homology to Coxsackie or proinsulin peptides do not crossreact with homologous counterpart

Type 1 diabetes mellitus is a T-cell mediated autoimmune disease in which the insulin-producing pancreatic beta cells are selectively destroyed. Molecular mimicry and T-cell crossreactivity to beta-cell autoantigens and environmental agents with sequence similarities have been a proposed mechanism underlying the pathogenesis of type 1 diabetes, but actual crossreactivity has not yet been demonstrated. We isolated and investigated T cells reactive to GAD65 peptides and homologous peptides of the Coxsackie virus protein P2C and proinsulin from recent onset type 1 diabetes patients, and tested their fine specificity and cytokine production profile. Six T-cell lines specific for GAD65 peptides (amino acids 491-530) with homology to proinsulin (B20-C14) were isolated from six newly diagnosed patients with type 1 diabetes, but none of the stable T-cell lines crossreacted to the homologous proinsulin peptides. Similarly, none of four T-cell lines reactive to GAD65 peptides (amino acids 247-280) with sequence homology to Coxsackie P2C (amino acids 30-50) crossreacted to the homologous viral peptide. Two T-cell lines corecognized a GAD65 peptide and a Coxsackie P2C peptide. However, the antigen-specific T-cell clones from these T-cell lines were reacting either with the GAD65 peptide or the Coxsackie P2C peptide using different restriction elements without crossreacting to the homologous peptide. Our data demonstrate that homologous peptides previously proposed to serve as targets for crossreactivity indeed are immunogenic. Yet, T-cell clones did not crossreact with linear sequence homologies, despite strong T-cell responses to individual peptides.

Proliferative responses to selected peptides of IA-2 in identical twins discordant for Type 1 diabetes

BACKGROUND

The aim of the study was to define T lymphocyte reactivity to selected peptides of an islet antigen IA-2, associated with Type 1 diabetes.

METHODS

We used 10 peptides selected from the IA-2 molecule due to their predicted ability to bind to HLA-DRB1*0401, a Type 1 diabetes-associated allele. We tested 21 identical twin pairs discordant for the disease and 15 control subjects and then followed them prospectively; seven non-diabetic twins developed diabetes.

RESULTS

Twins of identical pairs tended to respond to different peptides suggesting that the T cell response is, to a degree, shaped by non-genetically determined factors (p<0. 0001). However, there was no difference in the T cell responses between diabetic twins and either their non-diabetic identical twins or control subjects and the response was heterogenous. T cell responses did not differ in those seven non-diabetic twins who developed diabetes from those twins who did not. T cell responses to peptide 11 (amino acids 502-514) was immunodominant in diabetic twins as well as their non-diabetic twins and controls; responses were not correlated with HLA, IA-2 antibodies, age or duration of disease.

CONCLUSION

We conclude that T cell responses to selected IA-2 peptides are not genetically determined, heterogeneous, not strictly HLA controlled and did not distinguish diabetic or prediabetic twins from non-diabetic twins or controls. The identification of an immunodominant T cell response to IA-2 peptide 502-514 raises the possibility that this, or similar, epitopes may be of therapeutic value in disease prevention.

Persistent T Cell Anergy in Human Type 1 Diabetes

An anergic phenotype has been observed in nonobese diabetic (NOD) mice and some autoreactive T cells from patients with type I diabetes. To better understand this phenomenon, we measured T cell proliferative responses to 10 diabetes-associated and up to 9 control Ags/peptides in 148 new diabetic children, 51 age- and MHC (DQ)-matched siblings (sibs), 31 patients with longstanding diabetes, and 40 healthy controls. Most (78–91%) patient and sib responses to glutamate decarboxylase of 65 kDa (GAD65), islet cell cytoplasmic autoantibody (ICA) 69, diabetes-associated T cell epitopes in ICA69 (Tep69), and heat shock protein (Hsp) 60 involved anergic T cells that required exogenous IL-2 to proliferate. Responses to proinsulin, IA-2 (and tetanus toxoid) required no IL-2 and generated sufficient cytokine to rescue anergic T cell responses. Most new patients (85%) had autoreactive T cells, three quarters targeting more than half of the diabetes Ags. Only 7.8% of the sibs and none of the controls had such multiple T cell autoreactivities, which thus characterize overt disease. Multiple anergic and nonanergic T cell autoreactivities were sustained during 2 yr follow-up after onset and in patients with longstanding (3–26 yr) diabetes. Activated patient T cells survived severe IL-2 deprivation, requiring 20–100 times less IL-2 than normal T cells to escape apoptosis. Diabetic T cell anergy thus persists for decades and is Ag and host specific but not related to disease course. Rescue by IL-2 from bystander T cells and high resistance to apoptosis may contribute to this persistence. These data explain some of the difficulties in the routine detection of disease-associated T cells, and they emphasize challenges for immunotherapy and islet transplantation.

Autoreactive T cell responses in insulin-dependent (Type 1) diabetes mellitus. Report of the first international workshop for standardization of T cell assays

Type 1 diabetes is thought to result from a T cell-mediated destruction of the pancreatic beta-cells. Multiple and sometimes conflicting studies have identified a variety of aberrations in the cellular immune response to autoantigens in persons with the disease. Potential explanations for these discrepancies include incomparable techniques or culture conditions, diversity in the populations of patients or controls tested, and differences in autoantigen preparations. A T cell workshop was organized by the Immunology of Diabetes Society with the aim of appreciating and identifying problems associated with autoreactive T cell assays in type 1 diabetes. As a first phase, a series of candidate autoantigens were analysed by reference laboratories for quality. Subsequently, these preparations, as well as control stimuli, were distributed in a blind fashion to 26 laboratories worldwide, including all experienced centres, for analysis of T cell proliferation assays in 10 recent onset type 1 diabetes and 10 non-diabetic controls. For this analysis, participants used their own assays and references. The islet autoantigen quality control analyses performed prior to the distribution indicate that the quality of recombinant autoantigen preparations requires improvement. For example, several T cell clones specific for glutamic acid decarboxylase (GAD65) were unable to cross-react with GAD65 expressed in baculovirus, yeast or bacteria. Moreover, autoantigens expressed in E. coli interfered with autoantigen-specific proliferation of both T cell clones and peripheral blood mononuclear cells. Nonetheless, responses could be measured to all autoantigen preparations evaluated in the workshop. During the blind phase of the study, all centres were able to reproducibly measure T cell responses to two identical samples of tetanus toxoid, but there was significant interlaboratory variation in sensitivity and extent of the proliferative response measured. Third, the results using candidate autoantigens indicated that although a few laboratories could distinguish type 1 diabetes patients from non-diabetic controls in proliferative responses to individual islet autoantigens, in general, no differences in T cell proliferation between the two groups could be identified. This first T cell workshop on T cell autoreactivity in type 1 diabetes confirms that this was a difficult area for interlaboratory investigations, but provided insight towards future efforts focused on standardizing autoreactive T cell measurements. Some previously reported conflicting results can in part be explained by the observed interlaboratory variability. The inability to discriminate normal controls from new onset type 1 diabetes patients suggests that measuring proliferative responses in PBMC represents an incomplete picture of the immune response, perhaps complicated by difficulties in identifying suitable antigens and assays for standardized use.

T-cell response to proinsulin and insulin in type 1 and pretype 1 diabetes

Insulin-dependent diabetes mellitus (IDDM) results from the selective destruction of pancreatic beta cells by a T cell-mediated autoimmune process. Insulin and proinsulin are the only known beta cell-specific autoantigens. Using short-term cultures of freshly isolated peripheral blood mononuclear cells, we evaluated T-cell responses to proinsulin and to insulin in IDDM patients and individuals at risk for IDDM. A proliferative T-cell response to proinsulin was observed in only 2 of 26 recent-onset IDDM subjects and 2 of 12 long-standing IDDM subjects and was associated with a proliferative response to insulin. In contrast, 5 of 13 islet cell autoantibody-positive first-degree relatives of IDDM patients showed a proliferative response to proinsulin alone, 3 of 13 to insulin alone, and 1 of 13 to both insulin and proinsulin. Overall, 9 of 13 ICA-positive first-degree relatives responded to either proinsulin or insulin. We observed an inverse relationship between antiinsulin antibodies and T-cell responses to insulin in ICA-positive first-degree relatives but not in long-standing IDDM patients. Our data indicate that proinsulin is a major antigen in IDDM and, further, illustrate the difference between the autoimmune response to insulin and the immune response to exogenous insulin.