The transCampus Metabolic Training Programme Explores the Link of SARS-CoV-2 Virus to Metabolic Disease

Currently, we are experiencing a true pandemic of a communicable disease by the virus SARS-CoV-2 holding the whole world firmly in its grasp. Amazingly and unfortunately, this virus uses a metabolic and endocrine pathway via ACE2 to enter our cells causing damage and disease. Our international research training programme funded by the German Research Foundation has a clear mission to train the best students wherever they may come from to learn to tackle the enormous challenges of diabetes and its complications for our society. A modern training programme in diabetes and metabolism does not only involve a thorough understanding of classical physiology, biology and clinical diabetology but has to bring together an interdisciplinary team. With the arrival of the coronavirus pandemic, this prestigious and unique metabolic training programme is facing new challenges but also new opportunities. The consortium of the training programme has recognized early on the need for a guidance and for practical recommendations to cope with the COVID-19 pandemic for the community of patients with metabolic disease, obesity and diabetes. This involves the optimal management from surgical obesity programmes to medications and insulin replacement. We also established a global registry analyzing the dimension and role of metabolic disease including new onset diabetes potentially triggered by the virus. We have involved experts of infectious disease and virology to our faculty with this metabolic training programme to offer the full breadth and scope of expertise needed to meet these scientific challenges. We have all learned that this pandemic does not respect or heed any national borders and that we have to work together as a global community. We believe that this transCampus metabolic training programme provides a prime example how an international team of established experts in the field of metabolism can work together with students from all over the world to address a new pandemic.

Circulating β cell-specific CD8+ T cells restricted by high-risk HLA class I molecules show antigen experience in children with and at risk of type 1 diabetes

In type 1 diabetes (T1D), autoreactive cytotoxic CD8+ T cells are implicated in the destruction of insulin-producing β cells. The HLA-B*3906 and HLA-A*2402 class I genes confer increased risk and promote early disease onset, suggesting that CD8+ T cells that recognize peptides presented by these class I molecules on pancreatic β cells play a pivotal role in the autoimmune response. We examined the frequency and phenotype of circulating preproinsulin (PPI)-specific and insulin B (InsB)-specific CD8+ T cells in HLA-B*3906+ children newly diagnosed with T1D and in high-risk HLA-A*2402+ children before the appearance of disease-specific autoantibodies and before diagnosis of T1D. Antigen-specific CD8+ T cells were detected using human leucocyte antigen (HLA) class I tetramers and flow cytometry was used to assess memory status. In HLA-B*3906+ children with T1D, we observed an increase in PPI5-12 -specific transitional memory CD8+ T cells compared to non-diabetic, age- and HLA-matched subjects. Furthermore, PPI5-12 -specific CD8+ T cells in HLA-B*3906+ children with T1D showed a significantly more antigen-experienced phenotype compared to polyclonal CD8+ T cells. In longitudinal samples from high-risk HLA-A*2402+ children, the percentage of terminal effector cells within the InsB15-24 -specific CD8+ T cells was increased before diagnosis relative to samples taken before the appearance of autoantibodies. This is the first study, to our knowledge, to report HLA-B*3906-restricted autoreactive CD8+ T cells in T1D. Collectively, our results provide evidence that β cell-reactive CD8+ T cells restricted by disease-associated HLA class I molecules display an antigen-experienced phenotype and acquire enhanced effector function during the period leading to clinical diagnosis, implicating these cells in driving disease.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Low-Dose Anti-Thymocyte Globulin (ATG) Preserves β-Cell Function and Improves HbA1c in New-Onset Type 1 Diabetes

OBJECTIVE

A pilot study suggested that combination therapy with low-dose anti-thymocyte globulin (ATG) and pegylated granulocyte colony-stimulating factor (GCSF) preserves C-peptide in established type 1 diabetes (T1D) (duration 4 months to 2 years). We hypothesized that 1) low-dose ATG/GCSF or 2) low-dose ATG alone would slow the decline of β-cell function in patients with new-onset T1D (duration <100 days).

RESEARCH DESIGN AND METHODS

A three-arm, randomized, double-masked, placebo-controlled trial was performed by the Type 1 Diabetes TrialNet Study Group in 89 subjects: 29 subjects randomized to ATG (2.5 mg/kg intravenously) followed by pegylated GCSF (6 mg subcutaneously every 2 weeks for 6 doses), 29 to ATG alone (2.5 mg/kg), and 31 to placebo. The primary end point was mean area under the curve (AUC) C-peptide during a 2-h mixed-meal tolerance test 1 year after initiation of therapy. Significance was defined as one-sided P value < 0.025.

RESULTS

The 1-year mean AUC C-peptide was significantly higher in subjects treated with ATG (0.646 nmol/L) versus placebo (0.406 nmol/L) (P = 0.0003) but not in those treated with ATG/GCSF (0.528 nmol/L) versus placebo (P = 0.031). HbA_1c was significantly reduced at 1 year in subjects treated with ATG and ATG/GCSF, P = 0.002 and 0.011, respectively.

CONCLUSIONS

Low-dose ATG slowed decline of C-peptide and reduced HbA_1c in new-onset T1D. Addition of GCSF did not enhance C-peptide preservation afforded by low-dose ATG. Future studies should be considered to determine whether low-dose ATG alone or in combination with other agents may prevent or delay the onset of the disease.

A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.

β-cell specific T-lymphocyte response has a distinct inflammatory phenotype in children with Type 1 diabetes compared with adults

AIM

To examine the hypothesis that the quality, magnitude and breadth of helper T-lymphocyte responses to β cells differ in Type 1 diabetes according to diagnosis in childhood or adulthood.

METHODS

We studied helper T-lymphocyte reactivity against β-cell autoantigens by measuring production of the pro-inflammatory cytokine interferon-γ and the anti-inflammatory cytokine interleukin-10, using enzyme-linked immunospot assays in 61 people with Type 1 diabetes (within 3 months of diagnosis, positive for HLA DRB1*0301 and/or *0401), of whom 33 were children/adolescents, and a further 91 were unaffected siblings.

RESULTS

Interferon-γ responses were significantly more frequent in children with Type 1 diabetes compared with adults (85 vs 61%; P = 0.04). Insulin and proinsulin peptides were preferentially targeted in children (P = 0.0001 and P = 0.04, respectively) and the breadth of the interferon-γ response was also greater, with 70% of children having an interferon-γ response to three or more peptides compared with 14% of adults (P < 0.0001). Islet β-cell antigen-specific interleukin-10 responses were similar in children and adults in terms of frequency, breadth and magnitude, with the exception of responses to glutamic acid decarboxylase 65, which were significantly less frequent in adults.

CONCLUSIONS

At diagnosis of Type 1 diabetes, pro-inflammatory autoreactivity is significantly more prevalent, focuses on a wider range of targets, and is more focused on insulin/proinsulin in children than adults. We interpret this as indicating a more aggressive immunological response in the younger age group that is especially characterized by loss of tolerance to proinsulin. These findings highlight the existence of age-related heterogeneity in Type 1 diabetes pathogenesis that could have relevance to the development of immune-based therapies.

Stimulated urine C-peptide creatinine ratio vs serum C-peptide level for monitoring of β-cell function in the first year after diagnosis of Type 1 diabetes

AIMS

To determine if urine C-peptide/creatinine ratio is a useful tool for monitoring β-cell function in new-onset Type 1 diabetes.

METHODS

Data were obtained from a prospective immunomodulation study in people with Type 1 diabetes ≤ 3 months from diagnosis, with a standard mixed-meal tolerance test and measurement of urine C-peptide/creatinine ratio carried out at 0, 3, 6, 9 and 12 months. The change in the insulin-dose-adjusted HbA_1c level was also correlated with the change in serum/urine C-peptide level during the 12-month follow-up period.

RESULTS

A significant reduction in urine C-peptide/creatinine ratio, measured after a mixed-meal, was reached at 9 months (-45.4%), whilst the reduction in stimulated serum C-peptide level reached significance after 3 months (-54.7%) in placebo-treated participants. Neither change in stimulated serum C-peptide nor change in urine C-peptide level correlated with each other, and nor did change in insulin-dose-adjusted HbA_1c level in the first 6 months, but all measures correlated significantly in the second half of the 12-month follow-up period.

CONCLUSION

Mixed-meal-stimulated urine C-peptide/creatinine ratio was similar to, although less sensitive than, stimulated serum C-peptide level in monitoring β-cell function during the first year after diagnosis. Because the former is significantly less invasive, it warrants inclusion in further studies in Type 1 diabetes and may represent an attractive alternative outcome measure in cohort studies and in children.

Proinsulin multi-peptide immunotherapy induces antigen-specific regulatory T cells and limits autoimmunity in a humanized model

Peptide immunotherapy (PIT) is a targeted therapeutic approach, involving administration of disease-associated peptides, with the aim of restoring antigen-specific immunological tolerance without generalized immunosuppression. In type 1 diabetes, proinsulin is a primary antigen targeted by the autoimmune response, and is therefore a strong candidate for exploitation via PIT in this setting. To elucidate the optimal conditions for proinsulin-based PIT and explore mechanisms of action, we developed a preclinical model of proinsulin autoimmunity in a humanized HLA-DRB1*0401 transgenic HLA-DR4 Tg mouse. Once proinsulin-specific tolerance is broken, HLA-DR4 Tg mice develop autoinflammatory responses, including proinsulin-specific T cell proliferation, interferon (IFN)-γ and autoantibody production. These are preventable and quenchable by pre- and post-induction treatment, respectively, using intradermal proinsulin-PIT injections. Intradermal proinsulin-PIT enhances proliferation of regulatory [forkhead box protein 3 (FoxP3(+))CD25(high) ] CD4 T cells, including those capable of proinsulin-specific regulation, suggesting this as its main mode of action. In contrast, peptide delivered intradermally on the surface of vitamin D3-modulated (tolerogenic) dendritic cells, controls autoimmunity in association with proinsulin-specific IL-10 production, but no change in regulatory CD4 T cells. These studies define a humanized, translational model for in vivo optimization of PIT to control autoimmunity in type 1 diabetes and indicate that dominant mechanisms of action differ according to mode of peptide delivery.

Characterization of the autoimmune response against the nerve tissue S100β in patients with type 1 diabetes

Type 1 diabetes results from destruction of insulin-producing beta cells in pancreatic islets and is characterized by islet cell autoimmunity. Autoreactivity against non-beta cell-specific antigens has also been reported, including targeting of the calcium-binding protein S100β. In preclinical models, reactivity of this type is a key component of the early development of insulitis. To examine the nature of this response in type 1 diabetes, we identified naturally processed and presented peptide epitopes derived from S100β, determined their affinity for the human leucocyte antigen (HLA)-DRB1*04:01 molecule and studied T cell responses in patients, together with healthy donors. We found that S100β reactivity, characterized by interferon (IFN)-γ secretion, is a characteristic of type 1 diabetes of varying duration. Our results confirm S100β as a target of the cellular autoimmune response in type 1 diabetes with the identification of new peptide epitopes targeted during the development of the disease, and support the preclinical findings that autoreactivity against non-beta cell-specific autoantigens may have a role in type 1 diabetes pathogenesis.

A distinct immunogenic region of glutamic acid decarboxylase 65 is naturally processed and presented by human islet cells to cytotoxic CD8 T cells

CD8 T cells specific for islet autoantigens are major effectors of β cell damage in type 1 diabetes, and measurement of their number and functional characteristics in blood represent potentially important disease biomarkers. CD8 T cell reactivity against glutamic acid decarboxylase 65 (GAD65) in HLA-A*0201 subjects has been reported to focus on an immunogenic region 114-123 (VMNILLQYVV), with studies demonstrating both 114-123 and 114-122 epitopes being targeted. However, the fine specificity of this response is unclear and the key question as to which epitope(s) β cells naturally process and present and, therefore, the pathogenic potential of CD8 T cells with different specificities within this region has not been addressed. We generated human leucocyte antigen (HLA)-A*0201-restricted CD8 T cell clones recognizing either 114-122 alone or both 114-122 and 114-123. Both clone types show potent and comparable effector functions (cytokine and chemokine secretion) and killing of indicator target cells externally pulsed with cognate peptide. However, only clones recognizing 114-123 kill target cells transfected with HLA-A*0201 and GAD2 and HLA-A*0201(+) human islet cells. We conclude that the endogenous pathway of antigen processing by HLA-A*0201-expressing cells generates GAD65114-123 as the predominant epitope in this region. These studies highlight the importance of understanding β cell epitope presentation in the design of immune monitoring for potentially pathogenic CD8 T cells.

Multi-parametric flow cytometric and genetic investigation of the peripheral B cell compartment in human type 1 diabetes

The appearance of circulating islet-specific autoantibodies before disease diagnosis is a hallmark of human type 1 diabetes (T1D), and suggests a role for B cells in the pathogenesis of the disease. Alterations in the peripheral B cell compartment have been reported in T1D patients; however, to date, such studies have produced conflicting results and have been limited by sample size. In this study, we have performed a detailed characterization of the B cell compartment in T1D patients (n = 45) and healthy controls (n = 46), and assessed the secretion of the anti-inflammatory cytokine interleukin (IL)-10 in purified B cells from the same donors. Overall, we found no evidence for a profound alteration of the B cell compartment or in the production of IL-10 in peripheral blood of T1D patients. We also investigated age-related changes in peripheral B cell subsets and confirmed the sharp decrease with age of transitional CD19(+) CD27(-) CD24(hi) CD38(hi) B cells, a subset that has recently been ascribed a putative regulatory function. Genetic analysis of the B cell compartment revealed evidence for association of the IL2-IL21 T1D locus with IL-10 production by both memory B cells (P = 6·4 × 10(-4) ) and islet-specific CD4(+) T cells (P = 2·9 × 10(-3) ). In contrast to previous reports, we found no evidence for an alteration of the B cell compartment in healthy individuals homozygous for the non-synonymous PTPN22 Trp(620) T1D risk allele (rs2476601; Arg(620) Trp). The IL2-IL21 association we have identified, if confirmed, suggests a novel role for B cells in T1D pathogenesis through the production of IL-10, and reinforces the importance of IL-10 production by autoreactive CD4(+) T cells.

Prevalence of anti-N-methyl-D-aspartate (NMDA) receptor [corrected] antibodies in patients with schizophrenia and related psychoses: a systematic review and meta-analysis

BACKGROUND

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is an autoimmune condition caused by immunoglobulin (Ig)G antibodies directed against the NR1 subunit of the NMDA glutamate receptor. Approximately 65% of cases present with psychiatric symptoms, particularly psychosis. It remains to be established whether anti-NMDA receptor antibodies can cause a 'purely' psychotic illness without overt neurological symptoms.

METHOD

We conducted a systematic literature search to establish what proportion of patients with schizophrenia and related psychoses have antibodies directed against the NMDA receptor. Studies were included if (a) subjects had a diagnosis of schizophrenia, schizophrenia spectrum disorder or first-episode psychosis (FEP) using standard criteria, (b) serum was analysed for the presence of anti-NMDA receptor antibodies; and (c) the purpose of the study was to look for the presence of anti-NMDA receptor antibodies in patients with a primary psychiatric diagnosis without clinical signs of encephalitis.

RESULTS

Seven studies were included, comprising 1441 patients, of whom 115 [7.98%, 95% confidence interval (CI) 6.69-9.50] were anti-NMDA receptor antibody positive. Of these, 21 (1.46%, 95% CI 0.94-2.23) patients were positive for antibodies of the IgG subclass. Prevalence rates were greater in cases than controls only for IgG antibodies; other subclasses are of less certain aetiological relevance. There was significant heterogeneity in terms of patient characteristics and the antibody assay used.

CONCLUSIONS

A minority of patients with psychosis are anti-NMDA receptor antibody positive. It remains to be established whether this subset of patients differs from antibody-negative patients in terms of underlying pathology and response to antipsychotic treatment, and whether immunomodulatory treatments are effective in alleviating psychotic symptoms in this group.

Identification and characterisation of peptide binding motifs of six autoimmune disease-associated human leukocyte antigen-class I molecules including HLA-B*39:06

Research on CD8 T cell-mediated inflammatory diseases requires a better understanding of target epitopes and the constraints placed upon these by major histocompatibility complex (MHC) class I binding restrictions, especially those that relate to predisposing alleles. We used linear trap quadrupole fourier transform (LTQ-FT) tandem mass spectrometry to identify naturally processed and presented peptides eluted from the MHC-negative myeloid leukaemia cell line K562 transfected with specific MHC class I genes. We provide information on the peptidome of HLA-B*39:06, which is associated with the autoimmune disease type 1 diabetes, and extend the analysis to include a further five human leukocyte antigen (HLA) alleles (HLA-A*02:01/-A*11:01/-A*24:02/-B*18:01/-B*38:01) studied under identical experimental conditions. We identified a total of 3095 individual peptides with a mascot score ≥40 (HLA-A*02:01 = 569 peptides, -A*11:01 = 904, A*24:02 = 257, -B*18:01 = 615, -B*38:01 = 453, -B*39:06 = 297). Peptides had a preferential length of nine amino acids and originated mainly from cytoplasmic or nuclear proteins. Eluted peptides revealed a strong binding motif with binding anchor positions at position 2 (P2) and the C-terminus (PΩ). Peptides eluted from HLA-A*02:01 showed a P2 preference for leucine (62% of total peptides have Leu at P2) and PΩ preference for valine (49%). Similar data are provided for HLA-A*11:01 (P2:Thr, 29%; PΩ:Lys, 49%), -A*24:02 (P2:Tyr, 78%; PΩ:Phe, 41%), -B*18:01 (P2:Glu, 77%; PΩ:Tyr, 32%), -B*38:01 (P2:His, 51%; PΩ:Leu, 45%) and -B*39:06 (P2:Arg/His, 24%; PΩ:Ala, 64%). This work thus gives an overview of the naturally processed and presented repertoire of several common and autoimmune disease-related HLA alleles, which may be useful in studying autoreactive CD8 T cell responses and the role of HLA in disease susceptibility.

Comparison of peptide-major histocompatibility complex tetramers and dextramers for the identification of antigen-specific T cells

Fluorochrome-conjugated peptide-major histocompatibility complex (pMHC) multimers are widely used for flow cytometric visualization of antigen-specific T cells. The most common multimers, streptavidin-biotin-based 'tetramers', can be manufactured readily in the laboratory. Unfortunately, there are large differences between the threshold of T cell receptor (TCR) affinity required to capture pMHC tetramers from solution and that which is required for T cell activation. This disparity means that tetramers sometimes fail to stain antigen-specific T cells within a sample, an issue that is particularly problematic when staining tumour-specific, autoimmune or MHC class II-restricted T cells, which often display TCRs of low affinity for pMHC. Here, we compared optimized staining with tetramers and dextramers (dextran-based multimers), with the latter carrying greater numbers of both pMHC and fluorochrome per molecule. Most notably, we find that: (i) dextramers stain more brightly than tetramers; (ii) dextramers outperform tetramers when TCR-pMHC affinity is low; (iii) dextramers outperform tetramers with pMHC class II reagents where there is an absence of co-receptor stabilization; and (iv) dextramer sensitivity is enhanced further by specific protein kinase inhibition. Dextramers are compatible with current state-of-the-art flow cytometry platforms and will probably find particular utility in the fields of autoimmunity and cancer immunology.

Progress in immune-based therapies for type 1 diabetes

Immune-based therapies that prevent type 1 diabetes or preserve metabolic function remaining at diagnosis have become a major objective for funding agencies and international trial consortia, and receive backing from notable patient advocate groups. The development of immune-based therapeutic strategies in this arena requires a careful balancing of the risks of the therapy against the potential benefits, because many individuals are diagnosed or identified as being at increased risk of disease in early childhood, a period when manipulation of the developing immune system should be undertaken with caution. In addition, a therapy exists (daily insulin injection) that is life-saving in the acute stages of disease and can be used effectively over a lifetime as maintenance. Conversely, the disease is increasing in incidence; is peaking in ever-younger age groups; carries significant risk of increased morbidity and early mortality; and remains difficult to manage effectively in many settings. With these issues in mind, in this article we review progress towards immune-based strategies for this chronic autoimmune disease.

Antibody combination therapy targeting CD25, CD70 and CD8 reduces islet inflammation and improves glycaemia in diabetic mice

Destruction of pancreatic islets in type 1 diabetes is caused by infiltrating, primed and activated T cells. In a clinical setting this autoimmune process is already in an advanced stage before intervention therapy can be administered. Therefore, an effective intervention needs to reduce islet inflammation and preserve any remaining islet function. In this study we have investigated the role of targeting activated T cells in reversing autoimmune diabetes. A combination therapy consisting of CD25-, CD70- and CD8-specific monoclonal antibodies was administered to non-obese diabetic (NOD) mice with either new-onset diabetes or with advanced diabetes. In NOD mice with new-onset diabetes antibody combination treatment reversed hyperglycaemia and achieved long-term protection from diabetes (blood glucose <13·9 mmol/l) in >50% of mice. In contrast, in the control, untreated group blood glucose levels continued to increase and none of the mice were protected from diabetes (P < 0·0001). Starting therapy early when hyperglycaemia was relatively mild proved critical, as the mice with advanced diabetes showed less efficient control of blood glucose and shorter life span. Histological analysis (insulitis score) showed islet preservation and reduced immune infiltration in all treated groups, compared to their controls. In conclusion, antibody combination therapy that targets CD25, CD70 and CD8 results in decreased islet infiltration and improved blood glucose levels in NOD mice with established diabetes.

Immunological pathways to β-cell damage in Type 1 diabetes

Following almost 30 years of intensive research, initiated by the observation that Type 1 diabetes development is associated with a characteristic pancreatic immune cell infiltrate, a picture is emerging of which of the diverse effector arms of the immune system are involved in β-cell destruction. Like any chronic pathology, there is considerable complexity, and our ability to model the disease is hampered by a lack of ready access to the target organ and limited longitudinal analyses. However, it seems that putative pathways can start to be ruled in and out, in part as a result of focused mechanistic studies that make use of new technologies, and in part through analysis of the outcomes of clinical trials of new agents aimed at halting the disease process. The picture that emerges suggests a pathway to prevention that may require combinations of therapeutic agents that target different aspects of the immune system and will need to be used with due attention to their risk-benefit profiles.

Broadening the translational immunology landscape

It is just over 5 years sinceClinical and Experimental Immunology came under the direction of a new team of Editors and made a concerted effort to refresh its approach to promoting clinical and applied immunology through its pages. There were two major objectives: to foster papers in a field which, at the time, we loosely termed ‘translational immunology’; and to create a forum for the presentation and discussion of immunology that is relevant to clinicians operating in this space. So, how are we doing with these endeavours? This brief paper aims to summarize some of the key learning points and successes and highlight areas in which translational gaps remain.

Developing combination immunotherapies for type 1 diabetes: recommendations from the ITN-JDRF Type 1 Diabetes Combination Therapy Assessment Group

Like many other complex human disorders of unknown aetiology, autoimmune-mediated type 1 diabetes may ultimately be controlled via a therapeutic approach that combines multiple agents, each with differing modes of action. The numerous advantages of such a strategy include the ability to minimize toxicities and realize synergies to enhance and prolong efficacy. The recognition that combinations might offer far-reaching benefits, at a time when few single agents have yet proved themselves in well-powered trials, represents a significant challenge to our ability to conceive and implement rational treatment designs. As a first step in this process, the Immune Tolerance Network, in collaboration with the Juvenile Diabetes Research Foundation, convened a Type 1 Diabetes Combination Therapy Assessment Group, the recommendations of which are discussed in this Perspective paper.

Level of major histocompatibility complex class I expression on endothelium in non-obese diabetic mice influences CD8 T cell adhesion and migration

An important prerequisite for development of insulitis and beta-cell destruction in type 1 diabetes is successful transmigration of autoreactive T cells across the islet endothelium. Previous work suggests that antigen presentation to T cells by endothelium, which requires endothelial cell expression of major histocompatibility complex (MHC) molecules, promotes tissue-specific T cell migration. We therefore tested the hypothesis that the level of endothelial MHC class I molecule expression in diabetes-prone mice directly influences autoreactive CD8 T cell migration. We investigated the immune phenotype of endothelial cells, focusing on endothelial MHC class I molecule expression in a range of different tissues and mouse strains, including non-obese diabetic (NOD) mice. In addition, we examined whether the level of expression of MHC class I molecules influences autoantigen-driven CD8 T cell transmigration. Using endothelial cell lines that expressed 'high' (NOD mouse), medium (NOD x C3H/HeJ F(1) generation mice) and no (C3H/HeJ) H-2K(d), we demonstrated in vitro that MHC levels have a profound effect on the activation, adhesion and transmigration of pathogenic, islet autoreactive CD8 T cells. The expression level of MHC class I molecules on endothelial tissues has a direct impact upon the efficiency of migration of autoreactive T cells. The immune phenotype of microvascular endothelium in NOD mice may be an additional contributory factor in disease predisposition or development, and similar phenotypes should be sought in human type 1 diabetes.

Increased resistance to CD4+CD25hi regulatory T cell-mediated suppression in patients with type 1 diabetes

Type I diabetes (T1D) is a T cell-mediated autoimmune disease characterized by loss of tolerance to islet autoantigens, leading to the destruction of insulin-producing beta cells. Peripheral tolerance to self is maintained in health through several regulatory mechanisms, including a population of CD4+CD25hi naturally occurring regulatory T cells (T(regs)), defects in which could contribute to loss of self-tolerance in patients with T1D. We have reported previously that near to T1D onset, patients demonstrate a reduced level of suppression by CD4+CD25hi T(regs) of autologous CD4+CD25- responder cells. Here we demonstrate that this defective regulation is also present in subjects with long-standing T1D (> 3 years duration; P = 0.009). No difference was observed in forkhead box P3 or CD127 expression on CD4+CD25hi T cells in patients with T1D that could account for this loss of suppression. Cross-over co-culture assays demonstrate a relative resistance to CD4+CD25hi T(reg)-mediated suppression within the CD4+CD25- T cells in all patients tested (P = 0.002), while there appears to be heterogeneity in the functional ability of CD4+CD25hi T(regs) from patients. In conclusion, this work demonstrates that defective regulation is a feature of T1D regardless of disease duration and that an impaired ability of responder T cells to be suppressed contributes to this defect.

Humoral and cellular immune responses to myelin protein peptides in chronic inflammatory demyelinating polyradiculoneuropathy

OBJECTIVES

Evidence that chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an autoimmune disease was sought, by studying cellular and humoral immune responses to peripheral nerve myelin proteins.

METHODS

40 CIDP, 36 healthy control subjects (HC) and subjects with non-immune mediated neuropathies (other neuropathies, ON) for antibodies were studied by ELISA and cellular responses by cytokine ELISPOT (INF gamma, IL10) and ELISA (IL17) to synthetic peptides representing P0, P2 and PMP22.

RESULTS

Antibodies to P0, P2 or PMP22 peptides were detected in only a minority of CIDP, both not treated (nT-CIDP) and treated (T-CIDP). IgG antibodies to P2(80-105) were significantly more frequent in CIDP than in HC (4/30 vs 0/32; p<0.05) but the difference from ON (1/25) was not significant. In ELISPOT assays, IFN gamma was detected at a low frequency in CIDP and did not differ from HC or ON. In contrast, IL10 responses against P2(1-85) were more frequent in nT and T-CIDP (7/24 and 3/16) than HC (0/36; p<0.001 and p<0.05, respectively). The production of IL17 in cell-culture supernatants was not increased.

CONCLUSIONS

Antibodies to non-conformational antigenic epitopes of myelin proteins rarely occur in CIDP. None of the myelin protein peptides elicited IFN gamma responses, but P2 elicited IL10 responses significantly more often in CIDP patients than in controls. This reactivity may be part of an antigen-specific Th2 type pathogenetic or regulatory mechanism or represent a transitory epiphenomenon due to nerve damage. In our study, P2 was the protein antigen most likely to be involved in the aberrant immune responses in CIDP.

Proinsulin peptide immunotherapy in type 1 diabetes: report of a first-in-man Phase I safety study

Immunotherapeutic strategies under consideration for type 1 diabetes include modification of the autoimmune response through antigen-specific routes. Administration of short peptides representing T cell epitopes targeted by patients with the disease represents one approach. This study evaluated safety and mechanistic outcomes during first-in-man intradermal administration of a human leucocyte antigen-DR4 (HLA-DR4)-restricted peptide epitope of proinsulin (C19-A3). This randomized, open-label study assessed two major theoretical risks of peptide immunotherapy, namely induction of allergic hypersensitivity and exacerbation of the proinflammatory autoimmune response, using clinical assessment and mechanistic assays in vitro. Patients with long-standing type 1 diabetes and HLA-DRB1*0401 genotype received 30 microg (n = 18) or 300 microg (n = 18) of peptide in three equal doses at 0, 1 and 2 months or no intervention (n = 12). Proinsulin peptide immunotherapy in the dosing regimen used is well tolerated and free from risk of systemic hypersensitivity and induction/reactivation of proinsulin-specific, proinflammatory T cells. Peptide-specific T cells secreting the immune suppressive cytokine interleukin (IL)-10 were observed at month 3 in four of 18 patients in the low-dose group (versus one of 12 in the control group; P = not significant). Mean IL-10 response to peptide in the low-dose group increased between 0 and 3 months (P = 0.05 after stimulation with 5 microM peptide in vitro) and then declined to baseline levels between 3 and 6 months (P = 0.01 at 10 microM peptide in vitro). These studies pave the way for future investigations in new-onset patients designed to examine whether proinsulin peptide immunotherapy has beneficial effects on markers of T cell autoimmunity and preservation of beta cell mass.

Immune responses to myelin proteins in Guillain-Barré syndrome

BACKGROUND

Potential target autoantigens in the demyelinating form of Guillain-Barré syndrome (GBS) include the myelin proteins PMP22, P0 and P2.

METHODS

We investigated immunoreactivity to P0, P2 and PMP22 proteins in 37 patients with GBS and 32 healthy controls.

RESULTS

Antibodies to PMP22 or P0 peptides were detected at presentation in only 5 out of 37 patients. In ELISPOT assays, blood mononuclear cells from 15 out of 24 patients with GBS, but none of the control subjects, produced interleukin-10 (IL-10) in response to peptides from proteins P0, P2 or PMP22 (p = 0.0003). The cells from only two patients produced interferon-gamma (IFN gamma). The cells from 11 patients with GBS had increased IL-10 responses to peptides representing sequences from the extracellular domains of PMP22 before intravenous immunoglobulin (IVIg) treatment (p = 0.006). The cells from 11 patients with GBS, including 7 who responded to the extracellular domains of PMP22, had increased IL-10 responses to the intracellular domain of P0 before (p = 0.005) and those from 9 patients after they had been treated with IVIg (p = 0.01).

CONCLUSIONS

Antibodies to P0 and PMP22 protein peptides do occur in GBS but are uncommon. Circulating mononuclear cell IFN gamma responses to P0, P2 and PMP22 myelin protein peptides are rare, but IL-10 responses occur significantly more often than in normal subjects. They might be part of a harmful pathogenetic process or represent a regulatory response.

Establishing humanized mice using stem cells: maximizing the potential

Studies on physiology and pathology as they relate to the immune system draw heavily upon rodent models. With the increasing impetus provided by initiatives in translational medicine, the demand for ever more sophisticated, 'humanized' murine models is greater than ever. However, the design and implementation of studies in such mice is far from trivial. Here we provide a technical perspective on the increasing interest in developing humanized mice. We give examples of primary data starting with the routine procurement of human donor material, through CD34(+) cell purification prior to engraftment to injection into immunocompromised mice. Our goal is to provide practical advice to the many investigators who may be commencing or considering such studies.

Translational mini-review series on type 1 diabetes: Immune-based therapeutic approaches for type 1 diabetes

Type 1 diabetes (T1D) is often considered the prototype organ-specific autoimmune disease in clinical immunology circles. The key disease features - precise destruction of a single endocrine cell type occurring on a distinct genetic and autoimmune background - have been unravelled in recent years to such an extent that there is a growing expectation that the disease should be curable. T1D is something of an orphan disease, currently managed by endocrinologists yet dependent upon the wit of immunologists, both basic and clinical, to find the best approaches to prevention and cure. Type 1 diabetes thus represents one of the most active arenas for translational research, as novel immune-based interventions find their way to the clinic. The first serious attempt at immune-based treatment for T1D was in 1984, the first at prevention in 1993; current and planned trials will take us into the next decade before reporting their results. This paper represents the first attempt at a comprehensive review of this quarter century of endeavour, documenting all the strategies that have emerged into clinical studies. Importantly, the intense clinical activity has established robust infrastructures for future T1D trials and frameworks for their design. The evident success of the monoclonal anti-CD3 antibody trials in established T1D demonstrate that modulation of islet autoimmunity in humans after the onset of overt disease can be achieved, and give some reason to be cautiously optimistic for the ability of these and other agents, alone and in combination, to provide an effective immunotherapy for the disease.

Translational mini-review series on type 1 diabetes: Systematic analysis of T cell epitopes in autoimmune diabetes

T cell epitopes represent the molecular code words through which the adaptive immune system communicates. In the context of a T cell-mediated autoimmune disease such as type 1 diabetes, CD4 and CD8 T cell recognition of islet autoantigenic epitopes is a key step in the autoimmune cascade. Epitope recognition takes place during the generation of tolerance, during its loss as the disease process is initiated, and during epitope spreading as islet cell damage is perpetuated. Epitope recognition is also a potentially critical element in therapeutic interventions such as antigen-specific immunotherapy. T cell epitope discovery, therefore, is an important component of type 1 diabetes research, in both human and murine models. With this in mind, in this review we present a comprehensive guide to epitopes that have been identified as T cell targets in autoimmune diabetes. Targets of both CD4 and CD8 T cells are listed for human type 1 diabetes, for humanized [human leucocyte antigen (HLA)-transgenic] mouse models, and for the major spontaneous disease model, the non-obese diabetic (NOD) mouse. Importantly, for each epitope we provide an analysis of the relative stringency with which it has been identified, including whether recognition is spontaneous or induced and whether there is evidence that the epitope is generated from the native protein by natural antigen processing. This analysis provides an important resource for investigating diabetes pathogenesis, for developing antigen-specific therapies, and for developing strategies for T cell monitoring during disease development and therapeutic intervention.

Primary and immortalised human pancreatic islet endothelial cells: phenotypic and immunological characterisation

AIMS/HYPOTHESIS

Studies on the biology of the microvascular endothelial cells (MECs) that surround and penetrate the pancreatic islets are hampered by difficulties in isolating and culturing large numbers of pure cells. We aimed to morphologically and functionally characterise primary MECs purified and cultured from human islets, and to establish a simian virus 40 (SV40)-immortalised cell line from these primary cultures.

MATERIALS AND METHODS

Human islet MECs were extracted and purified using anti-CD105 coated immunomagnetic beads, and endothelial markers and surface molecules analysed by flow cytometric analysis. An immortalised cell line was then established by using a chimeric adeno5/SV40 virus.

RESULTS

Islet MECs expressed classic and specific endothelial markers, a high basal level of intercellular adhesion molecule-1, and low levels of E-selectin and TNF (previously known as TNF-alpha) inducible vascular cell adhesion molecule-1. IFNG (previously known as IFN-gamma) induced expression of HLA class II molecules. The immortalised islet MECs expanded rapidly, exhibited increased DNA synthesis, and were passaged approximately 30 times, without signs of senescence. They retained the endothelial characteristics of the parental cells, and behaved as the primary cells in terms of TNF stimulation of expression of adhesion molecules and support of leucocyte adhesion and transmigration.

CONCLUSIONS/INTERPRETATION

The immortalised islet MECs that we have established could effectively represent a substitute for primary counterparts for in vitro studies on the role of the microvasculature in pathophysiological processes involved in type 1 and type 2 diabetes.

Expression of nephrin by human pancreatic islet endothelial cells

AIMS/HYPOTHESIS

The islet microcirculation has morphological characteristics resembling those of renal glomeruli. Transcription of the nephrin gene, a highly specific barrier protein of the slit diaphragm of podocyte foot processes, has been reported in the pancreas, although its cellular localisation and function remain to be defined. In this study, we purified and characterised microvascular endothelial cells (MECs) isolated from human islets and investigated the expression and distribution of nephrin on these cells.

METHODS

Human islet MECs were extracted and purified using anti-CD105-coated immunomagnetic beads and their endothelial characteristics were confirmed by expression of classical endothelial markers and basal high-level expression of intercellular adhesion molecule-1 and TNF-alpha-inducible vascular cell adhesion molecule-1. Nephrin expression was assessed by immunofluorescence, flow cytometric analysis and western blotting on cell lysates, as well as by RT-PCR.

RESULTS

Immunofluorescence studies detected nephrin in a fine, punctate, diffuse pattern on cultured islet MECs, and also in human pancreatic islet sections. In both cases nephrin colocalised with endothelial markers. TNF-alpha treatment induced a marked reduction and redistribution of the protein in one or multiple aggregates. Nephrin expression was confirmed by flow cytometry, western blotting and RT-PCR studies. In contrast, nephrin could not be detected at the protein or mRNA level in human macro- and microvascular cells from other sites.

CONCLUSIONS/INTERPRETATION

Nephrin is expressed at protein and mRNA levels in islet microendothelium, supporting the hypothesis that islet MECs exhibit distinctive morphological characteristics that indicate functional specialisation of potential pathophysiological importance.

High levels of type 2 cytokine-producing cells in chronic fatigue syndrome

The aetiology of chronic fatigue syndrome (CFS) is not known. However, it has been suggested that CFS may be associated with underlying immune activation resulting in a Th2-type response. We measured intracellular production of interferon (IFN)-gamma and interleukin (IL)-2; type 1 cytokines), IL-4 (type 2) and IL-10 (regulatory) by both polyclonally stimulated and non-stimulated CD4 and CD8 lymphocytes from patients with CFS and control subjects by flow cytometry. After polyclonal activation we found evidence of a significant bias towards Th2- and Tc2-type immune responses in CFS compared to controls. In contrast, levels of IFN-gamma, IL-2 and IL-10-producing cells were similar in both study groups. Non-stimulated cultures revealed significantly higher levels of T cells producing IFN-gamma or IL-4 in CFS patients. Concluding, we show evidence for an effector memory cell bias towards type 2 responsiveness in patients with CFS, as well as ongoing type 0 immune activation in unstimulated cultures of peripheral blood cells.

Promiscuous binding of proinsulin peptides to Type 1 diabetes-permissive and -protective HLA class II molecules

AIMS/HYPOTHESIS

Presentation of peptide epitopes derived from beta-cell autoantigens, such as insulin and its precursor molecules, by MHC class II molecules to autoreactive T-cells is believed to play a role in the development of Type 1 diabetes. However, little is known about the interaction between peptides of (prepro)insulin and MHC class II molecules permissive and protective for Type 1 diabetes. In this study therefore, peptides spanning the human preproinsulin sequence were assessed for their binding characteristics to Type 1 diabetes-protective and -permissive HLA molecules.

METHODS

HLA-DR2, -DQ6.2 (Type 1 diabetes-protective) and HLA-DR4, -DQ8 (Type 1 diabetes permissive) molecule binding affinity for overlapping synthetic 20mer peptides spanning human preproinsulin was measured in a direct competition binding assay against a biotinylated indicator peptide.

RESULTS

All HLA molecules tested showed similarity in their binding characteristics across the preproinsulin molecule, with regions of the insulin A-chain showing the highest affinity and C-peptide regions the lowest affinity for all HLA molecules tested. Furthermore, an insulin peptide implicated as a major CD4+ T-cell target in disease pathogenesis (B9-23) had high affinity binding to both protective and permissive HLA molecules but did not represent the highest affinity region of (prepro)insulin identified in either case.

CONCLUSION/INTERPRETATION

The results suggest that peptide binding affinity alone is unlikely to be the major determinant of disease susceptibility in relation to interactions between (prepro)insulin epitopes and HLA molecules. The identification of epitopes derived from beta-cell autoantigens that bind promiscuously to diabetes-permissive HLA molecules could be important in the design of peptide-based immunotherapeutic strategies for the prevention of Type 1 diabetes.

Antinuclear autoantibodies (ANA) in Gulf War-related illness and chronic fatigue syndrome (CFS) patients

It is established that veterans of the 1991 Gulf War have an increased frequency of experiencing multiple symptoms. The underlying mechanism of these ailments is unclear, although they do not correspond to any clearly defined syndrome. The most common symptoms overlap with those of chronic fatigue syndrome (CFS). CFS was recently associated with a novel subtype of antinuclear autoantibody (ANA) that reacts with nuclear envelope (NE) antigens. NE autoantibodies are not known to be linked with any distinct clinical condition, but have been observed in patients with unusual mixed chronic autoimmune disorders and connective tissue diseases. In this study we examined whether NE ANAs are a feature of patients with CFS and symptomatic Gulf War veterans (sGWV). We studied the prevalence of ANA in 130 sGWV, 90 well Gulf War veterans (wGWV), 128 symptomatic Bosnia and Era veterans (sBEV), 100 CFS patients, and 111 healthy control subjects matching for age and sex. We found no significant difference in the prevalence of ANAs between any of the groups. None of the patients/or veterans we studied had ANA of the NE type. Our results show that multisymptom illness due to CFS or related to Gulf War service is not associated with antinuclear autoimmunity.

3 beta hydroxysteroid dehydrogenase autoantibodies in patients with idiopathic premature ovarian failure target N- and C-terminal epitopes

The steroid cell enzyme 3 beta hydroxysteroid dehydrogenase (3 beta HSD) has been identified as a target of steroid cell autoantibodies, and autoantibodies to this enzyme are present in patients with premature ovarian failure and patients with autoimmune polyendocrine syndrome 1. The aim of the present study was to develop a radioligand binding assay for 3 beta HSD autoantibodies and to exploit this to examine regions of the molecule targeted by autoantibodies. We generated a construct of 3 beta HSD coupled to a luciferase fusion partner in order to maximize the yield of (35)S-radiolabeled protein. Labeled 3 beta HSD was then immunoprecipitated and the autoantibodies quantified by phosphoimaging. Autoantibodies to 3 beta HSD were detected in 12 of 100 (12%) idiopathic premature ovarian failure patients and 0 of 103 (0%) healthy age-matched controls (P < 0.0001). Three overlapping fragments of 3 beta HSD cDNA were cloned downstream of luciferase to examine autoantibody binding sites. Two of nine sera with 3 beta HSD autoantibodies (22%) displayed reactivity to the N terminus of 3 beta HSD, and seven (77%) showed reactivity to the C terminal; no sera reacted with the middle region. Our study demonstrates a markedly enhanced disease specificity of autoantibodies to 3 beta HSD detected using this novel assay and shows that distinct regions of the molecule are targeted.

T cell activation by coxsackievirus B4 antigens in type 1 diabetes mellitus: evidence for selective TCR Vbeta usage without superantigenic activity

Numerous clinical and epidemiological studies link enteroviruses such as the Coxsackie virus group with the autoimmune disease type 1 diabetes mellitus (DM). In addition, there are reports that patients with type 1 DM are characterized by skewing of TCR Vbeta chain selection among peripheral blood and intraislet T lymphocytes. To examine these issues, we analyzed TCR Vbeta chain-specific up-regulation of the early T cell activation marker, CD69, on CD4 T cells after incubation with Coxsackievirus B4 (CVB4) Ags. CD4 T cells bearing the Vbeta chains 2, 7, and 8 were the most frequently activated by CVB4. Up-regulation of CD69 by different TCR families was significantly more frequent in new onset type 1 DM patients (p = 0.04), 100% of whom (n = 8) showed activation of CD4 T cells bearing Vbeta8, compared with 50% of control subjects (n = 8; p = 0.04). T cell proliferation after incubation with CVB4 Ags required live, nonfixed APCs, suggesting that the selective expansion of CD4 T cells with particular Vbeta chains resulted from conventional antigen processing and presentation rather than superantigen activity. Heteroduplex analysis of TCR Vbeta chain usage after CVB4 stimulation indicated a relatively polyclonal, rather than oligo- or monoclonal response to viral Ags. These results provide evidence that new-onset patients with type 1 DM and healthy controls are primed against CVB4, and that CD4 T cell responses to the virus have a selective TCR Vbeta chain usage which is driven by viral Ags rather than a superantigen.

Characterization of preparations of GAD65, proinsulin, and the islet tyrosine phosphatase IA-2 for use in detection of autoreactive T-cells in type 1 diabetes: report of phase II of the Second International Immunology of Diabetes Society Workshop for Standardization of T-cell assays in type 1 diabetes

The identification, quantification, and characterization of T-cells reactive with the islet autoantigens GAD65, proinsulin (PI), and tyrosine phosphatase-like molecules IA-2 and phogrin are major research goals in type 1 diabetes. In the Immunology of Diabetes Society First Workshop on Autoreactive T-Cells, the quality of recombinant preparations of these autoantigens was identified as a significant weakness, a finding that may account for much of the inconsistency in published studies of peripheral blood T-cell reactivity to islet autoantigens. Poor antigen quality has also hampered the development of novel technologies for the detection of islet-reactive T-cells. For these reasons, in the present study, several preparations of GAD65, PI, and IA-2 were collected and evaluated for endotoxin content, ability to stimulate a panel of relevant T-cell clones, and inhibitory effects on proliferation to unrelated third-party antigens. Through this process, we have been able to identify preparations of GAD65 and IA-2, generated in insect cells using the baculovirus expression system, that stimulate relevant clones and display low inhibitory effects on third-party antigens. In addition, we characterized a PI preparation generated in bacteria as being free of effects on proliferation to third-party antigens and low in endotoxin content. These preparations are important to promote the development of robust and sensitive assays of islet-reactive T-cells in patients with type 1 diabetes or patients at high risk for developing the disease.

Lack of association between HLA genotype and chronic fatigue syndrome

Although the aetiology of chronic fatigue syndrome is controversial, evidence that infective agents including viruses may have a role in the development of the condition has led to studies seeking an association with the immunomodulatory HLA genes. In the present study, we sought to extend previous work using a well-characterized patient group and modern HLA genotyping techniques. Fifty-eight patients were phenotyped for HLA A and B by microcytotoxicity and genotyped for HLA DRB, DQB and DPB by PCR oligoprobing, and the frequencies of antigens so assigned were compared with those from a control group of 134. No significant differences in HLA frequencies were found between patient and control groups. Thus, this study does not confirm previous findings of an HLA association with chronic fatigue syndrome, suggesting that neither presentation of viral antigen by HLA class I nor antigen processing genes in the HLA region is a major contributory factor in the development of the disease.

T-Cell reactivity to the P2C nonstructural protein of a diabetogenic strain of coxsackievirus B4

Enteroviruses are proposed as initiating factors in the etiology of Type 1 diabetes mellitus (Type 1 DM). Molecular mimicry between the autoantigen glutamic acid decarboxylase 65 (GAD65) and the coxsackievirus B4 (CVB4) nonstructural protein P2C is frequently cited as a mechanism by which this virus triggers the disease, but little is known about the immunogenicity of this viral protein in humans, mainly due to the problem of obtaining highly pure preparations of P2C. We generated large amounts of highly pure, soluble P2C protein, coupled to the fusion partner maltose binding protein (MBP-P2C) using the PMAL-c2 bacterial expression plasmid and a two-step purification system comprising amylose resin and ion exchange. Using purified viral protein we show that specific T-cell responses against P2C are detected in the blood of healthy donors and Type 1 DM patients. Proliferation responses to P2C were detected only in subjects also demonstrating T-cell proliferation to CVB4 Vero cell lysates. However, in additional cases T-cell responses to P2C were detectable through the release of interferon-gamma or interleukin-4 in individuals who did not make proliferative responses. Taken together, our data show that the P2C nonstructural protein of CVB4 is targeted by T cells during the antiviral immune response and may trigger the production of T helper 1 and T helper 2 cytokines. The availability of pure, immunogenic P2C should allow the putative role of antiviral responses in the development of autoimmune diabetes to be investigated.

Naturally processed and presented epitopes of the islet cell autoantigen IA-2 eluted from HLA-DR4

During immune responses, antigen-presenting cells (APCs) process antigens and present peptide epitopes complexed with human leukocyte antigen (HLA) molecules. CD4 cells recognize these naturally processed and presented epitopes (NPPEs) bound to HLA class II molecules. Epitope identification is important for developing diagnostic and therapeutic tools for immune-mediated diseases and providing insight into their etiology, but current approaches overlook effects of natural processing on epitope selection. We have developed a technique to identify NPPEs using mass spectrometry (MS) after antigen is targeted onto APCs using a lectin-based antigen delivery system (ADS). We applied the technique to identify NPPEs of the intracellular domain of the type 1 diabetes mellitus-associated (type 1 DM-associated) autoantigen insulinoma-associated-2 (IA-2ic), presented by HLA-DR4 (0401). IA-2ic-derived NPPEs eluted from HLA-DR4 constitute 6 sets of peptides nested around distinct core regions. Synthetic peptides based on these regions bind HLA-DR4 and elicit primary T-cell proliferation frequently in HLA-DR4-positive type 1 DM patients, but rarely in non-HLA-DR4 patients, and in none of the HLA-DR4 nondiabetic controls we tested. This flexible, direct approach identifies an HLA allele-specific map of NPPEs for any antigen, presented by any HLA class II molecule. This method should enable a greater understanding of epitope selection and lead to the generation of sensitive and specific reagents for detecting autoreactive T cells.

Prevalence of autoantibodies to autonomic nervous tissue structures in Type 1 diabetes mellitus

AIMS

The pathogenesis of diabetic autonomic neuropathy is multifactorial, but recent studies have suggested a link between the presence of autoantibodies to nervous tissue structures and severe, symptomatic autonomic neuropathy. The present study was designed to examine the true prevalence of these autoantibodies in a large clinic-based population of Type 1 diabetic patients compared to nondiabetic controls.

METHODS

The presence of complement fixing autoantibodies to vagus nerve (CF-VN), sympathetic ganglion (CF-SG) and adrenal medulla (CF-ADM) was assessed by immunofluorescence in a large cohort of patients (n = 394) of varying duration of Type 1 DM (median 28 years, range 6 months to 73 years) and 160 age and sex-matched nondiabetic control subjects.

RESULTS

All three autoantibodies were frequently detected in Type 1 DM (CF-VN, 22.1%; CF-SG, 30.7%; CF-ADM, 13.2%) but only rarely in healthy control subjects (4.4%, 4.4% and 3.1%, respectively; P < 0.0005 for all). There was no association between any of the autoantibodies and retinopathy (fundoscopy), peripheral somatic neuropathy (biothesiometry) or nephropathy (urinary albumin-creatinine ratio).

CONCLUSIONS

Our results on this large cohort establish the extensive presence of autonomic nervous tissue autoantibodies in Type 1 DM. Their role in reflecting, causing or predicting autonomic neuropathy remains to be determined.

Spontaneous T-cell proliferation in the non-obese diabetic mouse to a peptide from the unique class II MHC molecule, I-Ag7, which is also protective against the development of autoimmune diabetes

AIMS/HYPOTHESIS

Major histocompatibility complex class II molecules present antigenic peptides to T-cells and have an important role in T-cell thymic education. The mechanism by which major histocompatibility complex alleles confer a high genetic risk for autoimmune diabetes is not known. One hypothesis is that during positive thymic selection, the peripheral T-cell repertoire is modelled by major histocompatibility complex-restricted presentation of self major histocompatibility complex molecule-derived peptides, some of which mimic tissue autoantigens. The sequence similarity between a known T-cell epitope of glutamic acid decarboxylase-65, 509:VPPSLRTLED and the non-obese diabetic mouse class II major histocompatibility complex molecule I-Ag7 86:VPTSLRRLEQ is consistent with this.

METHODS

We measured spontaneous proliferation of peripheral T-cells from non-obese diabetic mice and other, non-diabetes-prone strains, to the I-Ag7 86-101 and glutamic acid decarboxylase-65(509-524) peptides, binding of these peptides to intact I-Ag7 and assessed the effect of tolerance induction on diabetes development, by injecting young non-obese diabetic mice with high doses of peptide.

RESULTS

T-cells from non-obese diabetic, but not other mice strains, spontaneously proliferate to the I-Ag7 86-101 and glutamic acid decarboxylase-65(509-524) peptides, but not control peptides. Both test peptides bind I-Ag7. Tolerance induction prolongs diabetes-free survival in non-obese diabetic mice when either the I-Ag7 86-101 or glutamic acid decarboxylase-65(509-524) peptide, but not control peptide, is used.

CONCLUSION/INTERPRETATION

A peptide from the unique class II major histocompatibility complex, diabetes-susceptibility molecule, I-Ag7, presented by I-Ag7 is a target of T-cell responses in diabetes-prone nonobese diabetic mice and tolerance induction against the peptide offers appreciable protection against the development of diabetes.