Chimeric antigen receptor (CAR) T cells targeting a pathogenic MHC class II:peptide complex modulate the progression of autoimmune diabetes.

A primary initiating epitope in the NOD mouse model of Type 1 Diabetes (T1D) lies between residues 9 and 23 of the insulin B chain. The B:9-23 peptide can bind to the NOD MHC class II molecule (I-Ag7) in multiple registers, but only one, (register 3, R3), creates complexes able to stimulate the majority of pathogenic B:9-23-specific CD4+ T cells. Previously we generated a monoclonal antibody (mAb287) that targets this critical I-Ag7-B:9-23(R3) complex. When given weekly to pre-diabetic mice at either early or late stages of disease, mAb287 was able to delay or prevent T1D in the treated animals. Although the precise mechanism of action of mAb287 remains unclear, we hypothesized that it may involve deletion of antigen presenting cells (APCs) bearing the pathogenic IAg7-B:9-23(R3) complexes, and that this process might be rendered more efficient by re-directing cytotoxic T cells using a mAb287 chimeric antigen receptor (287-CAR). As anticipated, 287-CAR T cells secreted IFN-γ in response to stimulation by I-Ag7-B:9-23(R3) complexes expressed on artificial APCs, but not I-Ag7 loaded with other peptides, and killed the presenting cells in vitro. A single infusion of 287-CAR CD8+ T cells to young (5 week old) NOD mice significantly delayed the onset of overt hyperglycemia compared to untreated animals (p = 0.022). None of the 287-CAR CD8+ T cell treated mice developed diabetes before 18 weeks of age, while 29% of control-CAR T cell treated mice (p = 0.044) and 52% of the un-treated mice (p = 0.0001) had developed T1D by this time. However, the protection provided by 287-CAR CD8+ T cells declined with time, and no significant difference in overall incidence by 30 weeks between the 3 groups was observed. Mechanistic studies indicated that the adoptively transferred 287-CAR T cells selectively homed to pancreatic lymph nodes, and in some animals could persist for at least 1-2 weeks post-transfer, but were essentially undetectable 10-15 weeks later. Our study demonstrates that CAR T cells specific for a pathogenic MHC class II:peptide complex can be effective in vivo, but that a single infusion of the current iteration can only delay, but not prevent, the development of T1D. Future studies should therefore be directed towards optimizing strategies designed to improve the longevity of the transferred cells.

Combinatorial detection of autoreactive CD8+ T cells with HLA-A2 multimers: a multi-centre study by the Immunology of Diabetes Society T Cell Workshop.

AIMS/HYPOTHESIS: Validated biomarkers are needed to monitor the effects of immune intervention in individuals with type 1 diabetes. Despite their importance, few options exist for monitoring antigen-specific T cells. Previous reports described a combinatorial approach that enables the simultaneous detection and quantification of multiple islet-specific CD8+ T cell populations. Here, we set out to evaluate the performance of a combinatorial HLA-A2 multimer assay in a multi-centre setting. METHODS: The combinatorial HLA-A2 multimer assay was applied in five participating centres using centralised reagents and blinded replicate samples. In preliminary experiments, samples from healthy donors were analysed using recall antigen multimers. In subsequent experiments, samples from healthy donors and individuals with type 1 diabetes were analysed using beta cell antigen and recall antigen multimers. RESULTS: The combinatorial assay was successfully implemented in each participating centre, with CVs between replicate samples that indicated good reproducibility for viral epitopes (mean %CV = 33.8). For beta cell epitopes, the assay was very effective in a single-centre setting (mean %CV = 18.4), but showed sixfold greater variability across multi-centre replicates (mean %CV = 119). In general, beta cell antigen-specific CD8+ T cells were detected more commonly in individuals with type 1 diabetes than in healthy donors. Furthermore, CD8+ T cells recognising HLA-A2-restricted insulin and glutamate decarboxylase epitopes were found to occur at higher frequencies in individuals with type 1 diabetes than in healthy donors. CONCLUSIONS/INTERPRETATION: Our results suggest that, although combinatorial multimer assays are challenging, they can be implemented in multiple laboratories, providing relevant T cell frequency measurements. Assay reproducibility was notably higher in the single-centre setting, suggesting that biomarker analysis of clinical trial samples would be most successful when assays are performed in a single laboratory. Technical improvements, including further standardisation of cytometry platforms, will likely be necessary to reduce assay variability in the multi-centre setting.

Regulatory vs. inflammatory cytokine T-cell responses to mutated insulin peptides in healthy and type 1 diabetic subjects.

Certain class II MHC (MHCII) alleles in mice and humans confer risk for or protection from type 1 diabetes (T1D). Insulin is a major autoantigen in T1D, but how its peptides are presented to CD4 T cells by MHCII risk alleles has been controversial. In the mouse model of T1D, CD4 T cells respond to insulin B-chain peptide (B:9-23) mimotopes engineered to bind the mouse MHCII molecule, IA(g7), in an unfavorable position or register. Because of the similarities between IA(g7) and human HLA-DQ T1D risk alleles, we examined control and T1D subjects with these risk alleles for CD4 T-cell responses to the same natural B:9-23 peptide and mimotopes. A high proportion of new-onset T1D subjects mounted an inflammatory IFN-γ response much more frequently to one of the mimotope peptides than to the natural peptide. Surprisingly, the control subjects bearing an HLA-DQ risk allele also did. However, these control subjects, especially those with only one HLA-DQ risk allele, very frequently made an IL-10 response, a cytokine associated with regulatory T cells. T1D subjects with established disease also responded to the mimotope rather than the natural B:9-23 peptide in proliferation assays and the proliferating cells were highly enriched in certain T-cell receptor sequences. Our results suggest that the risk of T1D may be related to how an HLA-DQ genotype determines the balance of T-cell inflammatory vs. regulatory responses to insulin, having important implications for the use and monitoring of insulin-specific therapies to prevent diabetes onset.

Monoclonal antibody blocking the recognition of an insulin peptide-MHC complex modulates type 1 diabetes.

The primary autoantigen triggering spontaneous type 1 diabetes mellitus in nonobese diabetic (NOD) mice is insulin. The major T-cell insulin epitope lies within the amino acid 9-23 peptide of the ß-chain (B:9-23). This peptide can bind within the peptide binding groove of the NOD MHC class II molecule (MHCII), IA(g7), in multiple positions or "registers." However, the majority of pathogenic CD4 T cells recognize this complex only when the insulin peptide is bound in register 3 (R3). We hypothesized that antibodies reacting specifically with R3 insulin-IA(g7) complexes would inhibit autoimmune diabetes specifically without interfering with recognition of other IA(g7)-presented antigens. To test this hypothesis, we generated a monoclonal antibody (mAb287), which selectively binds to B:9-23 and related variants when presented by IA(g7) in R3, but not other registers. The monoclonal antibody blocks binding of IA(g7)-B:10-23 R3 tetramers to cognate T cells and inhibits T-cell responses to soluble B:9-23 peptides and NOD islets. However, mAb287 has no effect on recognition of other peptides bound to IA(g7) or other MHCII molecules. Intervention with mAb287, but not irrelevant isotype matched antibody, at either early or late stages of disease development, significantly delayed diabetes onset by inhibiting infiltration by not only insulin-specific CD4 T cells, but also by CD4 and CD8 T cells of other specificities. We propose that peptide-MHC-specific monoclonal antibodies can modulate autoimmune disease without the pleiotropic effects of nonselective reagents and, thus, could be applicable to the treatment of multiple T-cell mediated autoimmune disorders.

Autoreactive T cells specific for insulin B:11-23 recognize a low-affinity peptide register in human subjects with autoimmune diabetes.

Previous studies in type 1 diabetes (T1D) in the nonobese diabetic mouse demonstrated that a crucial insulin epitope (B:9-23) is presented to diabetogenic CD4 T cells by IA(g7) in a weakly bound register. The importance of antigenic peptides with low-affinity HLA binding in human autoimmune disease remains less clear. The objective of this study was to investigate T-cell responses to a low-affinity self-epitope in subjects with T1D. HLA-DQ8 tetramers loaded with a modified insulin peptide designed to improve binding the low-affinity register were used to visualize T-cell responses following in vitro stimulation. Positive responses were only detectable in T1D patients. Because the immunogenic register of B:9-23 presented by DQ8 has not been conclusively demonstrated, T-cell assays using substituted peptides and DQ8 constructs engineered to express and present B:9-23 in fixed binding registers were used to determine the immunogenic register of this peptide. Tetramer-positive T-cell clones isolated from T1D subjects that responded to stimulation by B:11-23 peptide and denatured insulin protein were conclusively shown to recognize B:11-23 bound to HLA-DQ8 in the low-affinity register 3. These T cells also responded to homologous peptides derived from microbial antigens, suggesting that their initial priming could occur via molecular mimicry. These results are in accord with prior observations from the nonobese diabetic mouse model, suggesting a mechanism shared by mouse and man through which T cells that recognize a weakly bound peptide can circumvent tolerance mechanisms and play a role in the initiation of autoimmune diseases, such as T1D.

Human type 1 diabetes is associated with T cell autoimmunity to zinc transporter 8.

Recently we demonstrated that zinc transporter 8 (ZnT8) is a major target of autoantibodies in human type 1 diabetes (T1D). Because the molecules recognized by T1D autoantibodies are typically also targets of autoreactive T cells, we reasoned that this would likely be the case for ZnT8. To test this hypothesis, IFN-γ-producing T cells specific for ZnT8 in the peripheral blood of 35 patients with T1D (<6 mo after onset at blood draw) and 41 age-matched controls were assayed by ELISPOT using a library of 23 overlapping dipeptide pools covering the entire 369 aa primary sequence. Consistent with our hypothesis, patients showed significantly higher T cell reactivity than the matched controls, manifest in terms of the breadth of the overall response and the magnitude of responses to individual pools. Therefore, the median number of pools giving positive responses (stimulation index ≥ 3) in the control group was 1.0 (range, 0-7) compared with 6.0 (range, 1-20; p < 0.0001) for the patients. Similarly, the median stimulation index of positive responses in controls was 3.1 versus 5.0 in the patients (p < 0.0001). Individually, 7 of 23 pools showed significant disease association (p < 0.001), with several of the component peptides binding the disease associated HLA-DR3 (0301) and -DR4 (0401) molecules in vitro. We conclude that ZnT8 is also a major target of disease-associated autoreactive T cells in human T1D, and we suggest that reagents that target ZnT8-specific T cells could have therapeutic potential in preventing or arresting the progression of this disease.

Zinc transporter 8 haploinsufficiency protects against beta cell dysfunction in type 1 diabetes by increasing mitochondrial respiration.

OBJECTIVE: Zinc transporter 8 (ZnT8) is a major humoral target in human type 1 diabetes (T1D). Polymorphic variants of Slc30A8, which encodes ZnT8, are also associated with protection from type 2 diabetes (T2D). The current study examined whether ZnT8 might play a role beyond simply being a target of autoimmunity in the pathophysiology of T1D. METHODS: The phenotypes of NOD mice with complete or partial global loss of ZnT8 were determined using a combination of disease incidence, histological, transcriptomic, and metabolic analyses. RESULTS: Unexpectedly, while complete loss of ZnT8 accelerated spontaneous T1D, heterozygosity was partially protective. In vivo and in vitro studies of ZnT8 deficient NOD.SCID mice suggested that the accelerated disease was due to more rampant autoimmunity. Conversely, beta cells in heterozygous animals uniquely displayed increased mitochondrial fitness under mild proinflammatory conditions. CONCLUSIONS: In pancreatic beta cells and immune cell populations, Zn2+ plays a key role as a regulator of redox signaling and as an independent secondary messenger. Importantly, Zn2+ also plays a major role in maintaining mitochondrial homeostasis. Our results suggest that regulating mitochondrial fitness by altering intra-islet zinc homeostasis may provide a novel mechanism to modulate T1D pathophysiology.

Mapping of conformational autoantibody epitopes in ZNT8.

BACKGROUND: Identification of the major humoral epitopes in zinc transporter 8 (ZnT8) will expand the range of biomarkers for human type 1 diabetes and may provide clues to the mechanisms governing disease progression. Our initial studies suggested that most ZnT8-reactive sera recognize conformational epitopes in the final 100aa region of the molecule. Subsequently we identified residue 325 as a major determinant in two epitopes linked to a genetic polymorphism with high minor allele frequency (rs13266634). The goal of the current study was to extend this analysis to identify non-polymorphic epitopes in ZnT8. METHODS: Although the carboxy-terminal domains of human and mouse ZnT8 are ∼80% identical, the mouse probe is not precipitated by the majority of human type 1 diabetes sera. Thus to identify key residues we systematically 'humanized' the mouse probe at each position that differs and evaluated the probes in radio-immunoassays. RESULTS: As previously reported, only the alteration of Q>R325 by itself showed any restoration of binding to human sera. However, when clusters of structurally adjacent variant residues were also changed an additional region of antigenicity was revealed that depended on residues R332, E333, K336, and K340. Using a panel of 112 sera from recent onset subjects tested with the hC325Q and m-R325R332E333K336K340 probes, 39.3% of the subjects were ZnT8(Q)A+ , of which 38.6% (17/44) also recognized the mouse probe. CONCLUSIONS: We conclude that the mR-REKK probe identifies a third major epitope in ZnT8 that may add to the diagnostic utility of measuring autoantibodies to this molecule.

Inherent Beta Cell Dysfunction Contributes to Autoimmune Susceptibility.

The pancreatic beta cell is a highly specialized cell type whose primary function is to secrete insulin in response to nutrients to maintain glucose homeostasis in the body. As such, the beta cell has developed unique metabolic characteristics to achieve functionality; in healthy beta cells, the majority of glucose-derived carbons are oxidized and enter the mitochondria in the form of pyruvate. The pyruvate is subsequently metabolized to induce mitochondrial ATP and trigger the downstream insulin secretion response. Thus, in beta cells, mitochondria play a pivotal role in regulating glucose stimulated insulin secretion (GSIS). In type 2 diabetes (T2D), mitochondrial impairment has been shown to play an important role in beta cell dysfunction and loss. In type 1 diabetes (T1D), autoimmunity is the primary trigger of beta cell loss; however, there is accumulating evidence that intrinsic mitochondrial defects could contribute to beta cell susceptibility during proinflammatory conditions. Furthermore, there is speculation that dysfunctional mitochondrial responses could contribute to the formation of autoantigens. In this review, we provide an overview of mitochondrial function in the beta cells, and discuss potential mechanisms by which mitochondrial dysfunction may contribute to T1D pathogenesis.

Intrinsic factor autoantibodies by luminescent immuno-precipitation system in patients with corpus atrophic gastritis.

BACKGROUND: Corpus atrophic gastritis (CAG) may lead to intrinsic factor (IF) deficiency and vitamin B12 malabsorption. Intrinsic factor autoantibodies (IFA) are considered markers of pernicious anemia, but their clinical utility in CAG has not been evaluated. This study aimed to assess IFA in CAG patients and controls using a luciferase immunoprecipitation system (LIPS). METHODS: Recombinant nanoluciferase-tagged IF secreted from transfected Expi293F cells was used as antigen in an IFA-LIPS assay. IFA IgG were measured in sera from subjects undergoing gastroscopy and biopsy (updated Sydney system) mainly for anemia (57%) or dyspepsia (34%). This cohort comprised 105 patients with histologically-proven-CAG (cases: median age 64 years, 68% females) and 110 subjects with suspected CAG that were histologically negative (controls: median age 67 years, 54% females). Cut-off values were selected by Q-Q-plot analysis (negative: <2.5 arbitrary units). RESULTS: IFA levels were higher in cases than in controls (Mann-Whitney:p < 10-5). The ROC-AUC was 0.67 (95%CI 0.60-0.73, p < 0.0001). The IFA LIPS sensitivity and specificity for CAG were 32% (95% CI 24-42) and 95% (95% CI 90-99). This diagnostic performance remained similar after stratification for the presence/absence of anemia, dyspepsia or vitamin B12 deficiency. IFA levels were higher in females compared with males (p = 0.0127). In females aged <65 years, IFA-positives were more prevalent than in males (43.5% vs 6.6%, p = 0.011). CONCLUSIONS: The IFA-LIPS assay discriminated between CAG patients and controls showing a good specificity (95%) at the cost of sensitivity (32%). IFA-positivity occurred independently from anemia and vitamin B12 deficiency, but was more frequent in younger females. IFA testing should be considered in patients at high clinical suspicion of CAG.

The diagnostic value of zinc transporter 8 autoantibody (ZnT8A) for type 1 diabetes in Chinese.

BACKGROUND: Zinc transporter-8 (ZnT8) was recently identified as a novel autoantigen in human type 1 diabetes (T1D). Autoantibody to ZnT8 (ZnT8A) was detected in up to 80% of patients with new-onset T1D and 26% of patients with T1D otherwise classified as negative on the basis of existing markers. As no data of ZnT8A in Chinese have been reported, we aim to evaluate the utility of ZnT8A for diagnosis of autoimmune T1D in Chinese relative to other autoantibody markers. METHODS: Radioligand binding assays were performed on 539 T1D sera using human ZnT8 carboxyterminal 325Arg construct or a dimer incorporating 325Arg and 325Trp alongside antibodies to glutamic acid decarboxylase (GADA) or insulinoma-associated protein 2 (IA-2A). The antigenic specificity was analysed in the context of clinical characteristics of the patients. RESULTS: ZnT8A were present in 24.1% (130 of 539) of patients with T1D versus 1.8% (10 of 555; P < 0.001) in type 2 diabetes. At diagnosis, ZnT8A and IA-2A were less prevalent in Chinese subjects with T1D than in Caucasian populations (both P < 0.001) but similar to Japanese. The diagnostic sensitivity of combined GADA, IA-2A and ZnT8A measurements reached 65.5% with ZnT8A detected in 13.5% (29 of 215) of GADA and/or IA-2A-negative subjects. ZnT8A prevalence was lower in older and fatter patients. ZnT8A+ alone patients were distinguished from Ab- ones (P < 0.05-0.001) on the basis of higher insulin requirement and lower systolic blood pressure level. CONCLUSION: ZnT8A is an independent marker for T1D in Chinese and combined with GADA and IA-2A enhances diagnostic sensitivity. ZnT8A may be associated with different clinical phenotypes than GADA or IA-2A.

[Value of zinc transporter 8 autoantibody in the diagnostic classification of acute-onset diabetics].

OBJECTIVE: to explore the application significance of zinc transporter 8 autoantibody (ZnT8A) in the diagnostic classification of acute-onset diabetics. METHODS: according to the status of glutamic acid decarboxylase antibody (GADA) and tyrosine phosphatase antibody (IA2-A), 453 acute-onset diabetics were divided into A+ subgroup (any antibody positive) and A- subgroup (both antibodies negative). A total of 555 type 2 diabetics and 405 healthy controls were recruited. The distribution and correlated factors of ZnT8A were analyzed in the acute-onset diabetic group and two subgroups (A+ and A-). The clinical characteristics were compared between the patients with ZnT8A positive alone and patients without any antibody. All these islet antibodies were measured by radioligand assay. RESULTS: the prevalence of ZnT8A in acute-onset diabetics was 24.3% and it was significantly higher than that in type 2 diabetics (1.8%) and healthy controls (1.0%) (both P < 0.01). The frequency of ZnT8A in A+ subgroup was much higher than A- subgroup (29.7% vs 15.8%, P < 0.01). The positive rates of ZnT8A were much higher in all the subgroups with age at onset of < 30 yr than those with ≥ 30 yr (0 - 9, 34.9%; 10 - 19, 26.7%; 20 - 29, 26.3% vs ≥ 30 yr, 18.3%; all P < 0.05); furthermore, the rates were also higher in BMI < 21.0 kg/m(2) and 21.0 - 25.0 kg/m(2) subgroups than in BMI > 25.0 kg/m(2) subgroup (25.5% and 25.9% vs 8.7%, both P < 0.05). The ZnT8A level was only positively correlated with IA2-A titer (r = 0.165, P = 0.01), but not related to such factors as GADA titer, age at onset, duration, body mass index, HbA1c and CP levels (all P > 0.05). As compared with Ab- patients, the patients with ZnT8A positive alone had much higher insulin injection dosage [(35.5 ± 9.3) U/d vs (29.8 ± 14.7) U/d, P < 0.05], and much lower systolic blood pressures [(107 ± 15) mm Hg vs (113 ± 16) mm Hg, P < 0.05] and diastolic blood pressures [(69 ± 12) mm Hg vs (73 ± 12) mm Hg, P < 0.05]. CONCLUSION: ZnT8A testing may be applied in the diagnostic classification of acute-onset diabetics, especially in those without an evidence of GADA and IA2-A since it helps to identify a clinical phenotype which is more similar to the classic type 1 diabetes.

ZIGIR, a Granule-Specific Zn2+ Indicator, Reveals Human Islet α Cell Heterogeneity.

Numerous mammalian cells contain abundant Zn2+ in their secretory granules, yet available Zn2+ sensors lack the desired specificity and sensitivity for imaging granular Zn2+. We developed a fluorescent zinc granule indicator, ZIGIR, that possesses numerous desired properties for live cell imaging, including >100-fold fluorescence enhancement, membrane permeability, and selective enrichment to acidic granules. The combined advantages endow ZIGIR with superior sensitivity and specificity for imaging granular Zn2+. ZIGIR enables separation of heterogenous ß cells based on their insulin content and sorting of mouse islets into pure α cells and ß cells. In human islets, ZIGIR facilitates sorting of endocrine cells into highly enriched α cells and ß cells, reveals unexpectedly high Zn2+ activity in the somatostatin granule of some δ cells, and uncovers variation in the glucagon content among human α cells. We expect broad applications of ZIGIR for studying Zn2+ biology and Zn2+-rich secretory granules and for engineering ß cells with high insulin content for treating diabetes.

Autoantibodies Toward ATP4A and ATP4B Subunits of Gastric Proton Pump H+,K+-ATPase Are Reliable Serological Pre-endoscopic Markers of Corpus Atrophic Gastritis.

INTRODUCTION: Noninvasive assessment of corpus atrophic gastritis (CAG), a condition at increased risk of gastric cancer, is based on the measurement of pepsinogens, gastrin, and Helicobacter pylori antibodies. Parietal cell autoantibodies (PCAs) against the gastric proton pump (ATP4) are potential serological biomarkers of CAG. The purpose of this study was to compare the diagnostic performance of PCA and pepsinogen I tests in patients with clinical suspicion of CAG with the histopathological evaluation of gastric biopsies as reference standard. METHODS: A prospective case-finding study was performed on 218 naive adult patients (131 women, median age 65 years) who underwent gastric biopsies to confirm/exclude CAG. Patients with histopathological CAG were defined as cases, conversely as controls. Autoantibodies against the individual alpha (ATP4A) and beta (ATP4B) subunits of ATP4 were measured by luciferase immunoprecipitation, and global PCA and pepsinogen I by enzyme-linked immunosorbent assay. RESULTS: Histopathology classified 107 subjects (49%) as cases (CAG+, autoimmune 81.2%, and multifocal extensive 18.8%) and 111 subjects (51%) as controls (CAG-). In cases, ATP4A, ATP4B, and PCA titers were increased compared with controls, whereas pepsinogen I was reduced (P < 0.0001 for all). ATP4B, ATP4A, and pepsinogen I tests showed sensitivities of 77%, 75%, and 73% and specificities of 88%, 88%, and 80%, respectively. The receiver operating characteristic (ROC) area under the ROC curve (AUC) of these serological biomarkers confirmed their ability to discriminate cases from controls (ATP4B = 0.838, ATP4A = 0.826, pepsinogen I = 0.775, and PCA = 0.805), whereas the partial ROC-pAUC90 analysis showed that the ATP4B test had the best diagnostic performance (P = 0.008 vs ATP4; P = 0.0002 vs pepsinogen I). The presence of autoimmune or extensive gastritis was not significantly different between ATP4B positive or negative cases (P = 0.217). DISCUSSION: PCAs are promising serological biomarkers for the identification of CAG in high-risk individuals, particularly in an autoimmune pattern but also in an extensive-multifocal atrophy pattern.

A monoclonal antibody with broad specificity for the ligands of insulin B:9-23 reactive T cells prevents spontaneous type 1 diabetes in mice.

Activation of T cells specific for insulin B chain amino acids 9 to 23 (B:9-23) is essential for the initiation of type 1 diabetes (T1D) in non-obese diabetic mice. We previously reported that peptide/MHC complexes containing optimized B:9-23 mimotopes can activate most insulin-reactive pathogenic T cells. A monoclonal antibody (mAb287) targeting these complexes prevented disease in 30-50% of treated animals (compared to 10% of animals given an isotype control). The incomplete protection is likely due to the relatively low affinity of the antibody for its ligand and limited specificity. Here, we report an enhanced reagent, mAb757, with improved specificity, affinity, and efficacy in modulating T1D. Importantly, mAb757 bound with nanomolar affinity to agonists of both "type A" and "type B" cells and suppressed "type B" cells more efficiently than mAb287. When given weekly starting at 4 weeks of age, mAb757 protected ~70% of treated mice from developing T1D for at least 35 weeks, while mAb287 only delayed disease in 25% of animals under the same conditions. Consistent with its higher affinity, mAb757 was also able to stain antigen-presenting cells loaded with B:9-23 mimotopes in vivo. We conclude that monoclonal antibodies that can block the presentation of pathogenic T cell receptor epitopes are viable candidates for antigen-specific immunotherapy for T1D.

Novel antigens in type 1 diabetes: the importance of ZnT8.

The presence of circulating islet cell autoantibodies distinguishes type 1A diabetes (T1D) from other diabetic syndromes and determination of autoantigen genes and proteins is instrumental in understanding T1D as a clinical entity and in investigating the pathogenesis of the disease. ZnT8 was recently defined as a candidate autoantigen based on a -bioinformatics analysis focused on discovery of beta-cell-specific proteins associated with the regulatory pathway of secretion. The native molecule does not lend itself easily to solution-phase autoantibody assays, but ligands based on the predicted domain structure and molecular modeling have led to robust diagnostic procedures showing high specificities and sensitivities that complement current T1D autoantibody assays and add to the predictive value of their measurement. The incorporation of genetic and structural epitope analysis into ZnT8A determinations adds a further dimension to its diagnostic value and understanding of its role in the autoimmune disease process.

High-Efficiency Generation of Antigen-Specific Primary Mouse Cytotoxic T Cells for Functional Testing in an Autoimmune Diabetes Model.

Type 1 Diabetes (T1D) is characterized by islet-specific autoimmunity leading to beta cell destruction and absolute loss of insulin production. In the spontaneous non-obese diabetes (NOD) mouse model, insulin is the primary target, and genetic manipulation of these animals to remove a single key insulin epitope prevents disease. Thus, selective elimination of professional antigen presenting cells (APCs) bearing this pathogenic epitope is an approach to inhibit the unwanted insulin-specific autoimmune responses, and likely has greater translational potential. Chimeric antigen receptors (CARs) can redirect T cells to selectively target disease-causing antigens. This technique is fundamental to recent attempts to use cellular engineering for adoptive cell therapy to treat multiple cancers. In this protocol, we describe an optimized T-cell retrovirus (RV) transduction and in vitro expansion protocol that generates high numbers of functional antigen-specific CD8 CAR-T cells starting from a low number of naive cells. Previously multiple CAR-T cell protocols have been described, but typically with relatively low transduction efficiency and cell viability following transduction. In contrast, our protocol provides up to 90% transduction efficiency, and the cells generated can survive more than two weeks in vivo and significantly delay disease onset following a single infusion. We provide a detailed description of the cell maintenance and transduction protocol, so that the critical steps can be easily followed. The whole procedure from primary cell isolation to CAR expression can be performed within 14 days. The general method may be applied to any mouse disease model in which the target is known. Similarly, the specific application (targeting a pathogenic peptide/MHC class II complex) is applicable to any other autoimmune disease model for which a key complex has been identified.

How C-terminal additions to insulin B-chain fragments create superagonists for T cells in mouse and human type 1 diabetes.

In type 1 diabetes (T1D), proinsulin is a major autoantigen and the insulin B:9-23 peptide contains epitopes for CD4+ T cells in both mice and humans. This peptide requires carboxyl-terminal mutations for uniform binding in the proper position within the mouse IAg7 or human DQ8 major histocompatibility complex (MHC) class II (MHCII) peptide grooves and for strong CD4+ T cell stimulation. Here, we present crystal structures showing how these mutations control CD4+ T cell receptor (TCR) binding to these MHCII-peptide complexes. Our data reveal stricking similarities between mouse and human CD4+ TCRs in their interactions with these ligands. We also show how fusions between fragments of B:9-23 and of proinsulin C-peptide create chimeric peptides with activities as strong or stronger than the mutated insulin peptides. We propose transpeptidation in the lysosome as a mechanism that could accomplish these fusions in vivo, similar to the creation of fused peptide epitopes for MHCI presentation shown to occur by transpeptidation in the proteasome. Were this mechanism limited to the pancreas and absent in the thymus, it could provide an explanation for how diabetogenic T cells escape negative selection during development but find their modified target antigens in the pancreas to cause T1D.

Autoantibodies Directed Toward a Novel IA-2 Variant Protein Enhance Prediction of Type 1 Diabetes.

We identified autoantibodies (AAb) reacting with a variant IA-2 molecule (IA-2var) that has three amino acid substitutions (Cys27, Gly608, and Pro671) within the full-length molecule. We examined IA-2var AAb in first-degree relatives of type 1 diabetes (T1D) probands from the TrialNet Pathway to Prevention Study. The presence of IA-2var-specific AAb in relatives was associated with accelerated progression to T1D in those positive for AAb to GAD65 and/or insulin but negative in the standard test for IA-2 AAb. Furthermore, relatives with single islet AAb (by traditional assays) and carrying both IA-2var AAb and the high-risk HLA-DRB1*04-DQB1*03:02 haplotype progress rapidly to onset of T1D. Molecular modeling of IA-2var predicts that the genomic variation that alters the three amino acids induces changes in the three-dimensional structure of the molecule, which may lead to epitope unmasking in the IA-2 extracellular domain. Our observations suggest that the presence of AAb to IA-2var would identify high-risk subjects who would benefit from participation in prevention trials who have one islet antibody by traditional testing and otherwise would be misclassified as "low risk" relatives.

Induction of indoleamine 2,3-dioxygenase by interferon-gamma in human islets.

Indoleamine 2,3-dioxygenase (IDO) catalyzes the initial, rate-limiting step of tryptophan (Trp) catabolism along the kynurenine (KYN) pathway, and its induction in cells of the immune system in response to cytokines has been implicated in the regulation of antigen presentation and responses to cell-mediated immune attack. Microarray and quantitative PCR analyses of isolated human islets incubated with interferon (IFN)-gamma for 24 h revealed increased expression of IDO mRNA (>139-fold) and Trp-tRNA synthase (WARS) (>17-fold) along with 975 other transcripts more than threefold, notably the downstream effectors janus kinase (JAK)2, signal transducer and activator of transcription (STAT)1, IFN-gamma regulatory factor-1, and several chemokines (CXCL9/MIG, CXCL10/IP10, CXCL11/1-TAC, CCL2, and CCL5/RANTES) and their receptors. IDO protein expression was upregulated in IFN-gamma-treated islets and accompanied by increased intracellular IDO enzyme activity and the release of KYN into the media. The response to IFN-gamma was countered by interleukin-4 and 1alpha-methyl Trp. Immunohistochemical localization showed IDO to be induced in cells of both endocrine, including pancreatic duodenal homeobox 1-positive beta-cells, and nonendocrine origin. We postulate that in the short term, IDO activation may protect islets from cytotoxic damage, although chronic exposure to various Trp metabolites could equally lead to beta-cell attrition.