A fundamental question about the pathogenesis of spontaneous autoimmune diabetes is whether there are primary autoantigens. For type 1 diabetes it is clear that multiple islet molecules are the target of autoimmunity in man and animal models. It is not clear whether any of the target molecules are essential for the destruction of islet beta cells. Here we show that the proinsulin/insulin molecules have a sequence that is a primary target of the autoimmunity that causes diabetes of the non-obese diabetic (NOD) mouse. We created insulin 1 and insulin 2 gene knockouts combined with a mutated proinsulin transgene (in which residue 16 on the B chain was changed to alanine) in NOD mice. This mutation abrogated the T-cell stimulation of a series of the major insulin autoreactive NOD T-cell clones. Female mice with only the altered insulin did not develop insulin autoantibodies, insulitis or autoimmune diabetes, in contrast with mice containing at least one copy of the native insulin gene. We suggest that proinsulin is a primary autoantigen of the NOD mouse, and speculate that organ-restricted autoimmune disorders with marked major histocompatibility complex (MHC) restriction of disease are likely to have specific primary autoantigens.

With the development of an insulin autoantibody (IAA) assay performed in 96-well filtration plates, we have evaluated prospectively the development of IAA in NOD mice (from 4 weeks of age) and children (from 7 to 10 months of age) at genetic risk for the development of type 1 diabetes. NOD mice had heterogeneous expression of IAA despite being inbred. IAA reached a peak between 8 and 16 weeks and then declined. IAA expression by NOD mice at 8 weeks of age was strongly associated with early development of diabetes, which occurred at 16 -18 weeks of age (NOD mice IAA ؉ at 8 weeks: 83% (5͞6) diabetic by 18 weeks versus 11% (1͞9) of IAA negative at 8 weeks; P < .01). In man, IAA was frequently present as early as 9 months of age, the first sampling time. Of five children found to have persistent IAA before 1 year of age, four have progressed to diabetes (all before 3.5 years of age) and the fifth is currently less than age 2. Of the 929 children not expressing persistent IAA before age 1, only one has progressed to diabetes to date (age onset 3), and this child expressed IAA at his second visit (age 1.1). In new onset patients, the highest levels of IAA correlated with an earlier age of diabetes onset. Our data suggest that the program for developing diabetes of NOD mice and humans is relatively ''fixed'' early in life and, for NOD mice, a high risk of early development of diabetes is often determined by 8 weeks of age. With such early determination of high risk of progression to diabetes, immunologic therapies in humans may need to be tested in children before the development of IAA for maximal efficacy.insulin autoantibodies ͉ radioassay ͉ type 1 diabetes T ype 1A diabetes mellitus, as defined by an expert panel of the American Diabetes Association, is characterized by the presence of antiislet autoantibodies (1). There has been tremendous progress in defining islet autoantigens and developing antiislet autoantibody assays (2-4). In the most recent Immunology of Diabetes Workshop, a series of antiislet autoantibody assays were compared (2). Although the GAD65 autoantibody (GAA) and ICA512 (IA-2) autoantibody (ICA512AA) assays showed good concordance between laboratories, the insulin autoantibody (IAA) assays were divergent, with marked differences between laboratories in sensitivity and specificity. In this workshop, many of the IAA assays utilizing Ͻ600 l of sera had sensitivities Ϸ1͞2 of those utilizing a larger volume of serum (2). It is likely that such marked differences in interlaboratory measurement of IAA and the technical difficulty of current assays contributes to differences in the reported importance of IAA for disease prediction.Despite the difficulties of IAA determination, a number of laboratories have routinely measured IAA with large sera volume assays for large series of patients followed to the development of diabetes. Studies from multiple countries have reported that IAA has an important role in diabetes prediction (5-8). Antiinsulin autoantibodies appear to be unique in that their levels are ...

It has been reported that an insulin 2 gene knockout, when bred onto nonobese diabetic (NOD) mice, accelerates diabetes. We produced insulin 1 gene knockout congenic NOD mice. In contrast to insulin 2, diabetes and insulitis were markedly reduced in insulin 1 knockout mice, with decreased and delayed diabetes in heterozygous females and no insulitis and diabetes in most homozygous female mice. Lack of insulitis was found for insulin 1 female homozygous knockout mice at 8, 12, and 37 weeks of age. Despite a lack of insulitis, insulin 1 homozygous knockout mice spontaneously expressed insulin autoantibodies. Administration of insulin peptide B:9 -23 of both insulin 1 and 2 to NOD mice induced insulin autoantibodies. Insulin 1 is not the only lymphocytic target of NOD mice. Insulin 1 homozygous knockout islets, when transplanted into recently diabetic wild-type NOD mice, became infiltrated with lymphocytes and only transiently reversed diabetes. These observations indicate that loss of either insulin gene can influence progression to diabetes of NOD mice and suggest that the preproinsulin 1 gene is crucial for the spontaneous development of NOD insulitis and diabetes.

PolyIC. These studies demonstrate that ''normal'' mice have autoreactive T lymphocytes able to rapidly target islets and insulin given appropriate MHC alleles and that a peripherally administered insulin peptide (an altered peptide ligand of which is in clinical trials) can enhance specific anti-islet autoimmunity. These first PolyIC͞insulin-induced murine models should provide an important tool to study the pathogenesis of type 1 diabetes with experimental autoimmune diabetes.

The expression of pro(insulin) in the thymus may lead to the negative selection of pro(insulin) autoreactive T cells and peripheral tolerance to this autoantigen in type 1 diabetes (T1D). We investigated whether proinsulin is expressed in the thymus of young nonobese diabetic (NOD) mice, whether T cells from naive NOD female mice at weaning are reactive to mouse proinsulin, and the role of proinsulin as a pathogenic autoantigen in T1D. Proinsulin II mRNA transcripts were detected in the thymus of 2-wk-old NOD mice at similar levels to other control strains. Despite this expression, proinsulin autoreactive T cells were detected in the periphery of 2- to 3-wk-old naive NOD mice. Peripheral T cells reactive to the insulin, glutamic acid decarboxylase 65 (GAD65), GAD67, and islet cell Ag p69 autoantigens were also detected in these mice, indicating that NOD mice are not tolerant to any of these islet autoantigens at this young age. T cell reactivities to proinsulin and islet cell Ag p69 exceeded those to GAD67, and T cell reactivity to proinsulin in the spleen and pancreatic lymph nodes was directed mainly against a p24–33 epitope that spans the B chain/C peptide junction. Intraperitoneal immunization with proinsulin perinatally beginning at 18 days of age delayed the onset and reduced the incidence of T1D. However, s.c. immunization with proinsulin initiated at 5 wk of age accelerated diabetes in female NOD mice. Our findings support the notion that proinsulin p24–33 may be a primary autoantigen epitope in the pathogenesis of T1D in NOD mice.

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Aims We conducted a national survey to clarify the characteristics and clinical course of type 1 diabetes related to antiprogrammed cell death-1 therapy. Methods We analyzed the detailed data of 22 patients that were collected using a Japan Diabetes Society survey and a literature database search. Results Among the 22 patients, 11 (50.0%) met the criteria for fulminant type 1 diabetes and 11 (50.0%) met the criteria for acute-onset type 1 diabetes. The average patient age was 63 years. The mean duration between the date of the first anti-PD-1 antibody injection and development of type 1 diabetes was 155 days and ranged from 13 to 504 days. Flu-like symptoms, abdominal symptoms, and drowsiness were observed in 27.8, 31.6, and 16.7% patients, respectively. Mean ± standard deviation or median (first quartile-third quartile) glucose levels, HbA1c levels, urinary C-peptide immunoreactivity levels, and fasting serum C-peptide immunoreactivity levels were 617 ± 248 mg/dl, 8.1 ± 1.3%, 4.1 (1.4-9.4) μg/day, and 0.46 (0.20-0.70) ng/ml, respectively. Seventeen of 20 patients (85.0%) developed ketosis, and 7 of 18 patients (38.9%) developed diabetic ketoacidosis. Ten of 19 patients (52.6%) showed at least one elevated pancreatic enzyme level at the onset and two of seven patients showed this elevation before diabetes onset. Only one of 21 patients was anti-glutamic acid decarboxylase antibody positive. Conclusions Anti-programmed cell death-1 antibody-related type 1 diabetes varies from typical fulminant type 1 diabetes to acute-onset type 1 diabetes. However, diabetic ketoacidosis was frequently observed at the onset of diabetes. An appropriate diagnosis and treatment should be provided to avoid life-threatening metabolic alterations.

Aims/hypothesis We analysed the association between humoral autoreactivity to zinc transporter-8 (ZnT8) and the SLC30A8 rs13266634 polymorphism (Arg325Trp), which is located at the most distal loop in the ZnT8 protein.Methods Autoantibodies to ZnT8 were determined by RIA in 270 patients with type 1 diabetes using ZnT8 carboxyterminal constructs (amino acids 268-369) carrying 325Trp (CW) and 325Arg(CR) and a hybrid construct (CW-CR). Forty-four ZnT8 autoantibody-positive sera with genomic DNA were used to examine the association between reactivity to ZnT8 constructs and the rs13266634 genotype. Results Seventy-five patients reacted to the CW-CR hybrid construct, whereas 37 and 36 patients reacted to the CW and CR constructs, respectively. All sera positive for either CW or CR autoantibodies were positive for CW-CR autoantibodies. Among 19 patients with a 325Arg(CC) genotype, 5% had CW-specific autoantibodies, 42% had CR-specific autoantibodies and 32% had dual reactivity. Conversely, 73% of 15 patients with the 325Trp(TT) genotype had CW-specific autoantibodies, no patients had CR-specific autoantibodies and 13% had dual reactivity. Nine of the ten patients (90%) with the CT genotype reacted with either CR or CW constructs. The titre of CR autoantibodies in patients carrying the C allele was significantly higher than that in TT homozygotes (p<0.0001). In contrast, the titre of CW autoantibodies in patients carrying a T allele was significantly higher than that in CC homozygotes (p<0.005). No evidence of an association between rs13266634 and type 1 diabetes was observed. Conclusions/interpretation These results indicate that variant residue at amino acid 325 is a key determinant of humoral autoreactivity to ZnT8 and that the SLC30A8 genotype is an important determinant of autoantibody specificity.