Investigation of the vitamin D receptor gene (VDR) and its interaction with protein tyrosine phosphatase, non-receptor type 2 gene (PTPN2) on risk of islet autoimmunity and type 1 diabetes: the Diabetes Autoimmunity Study in the Young (DAISY).

The present study investigated the association between variants in the vitamin D receptor gene (VDR) and protein tyrosine phosphatase, non-receptor type 2 gene (PTPN2), as well as an interaction between VDR and PTPN2 and the risk of islet autoimmunity (IA) and progression to type 1 diabetes (T1D). The Diabetes Autoimmunity Study in the Young (DAISY) has followed children at increased risk of T1D since 1993. Of the 1692 DAISY children genotyped for VDR rs1544410, VDR rs2228570, VDR rs11568820, PTPN2 rs1893217, and PTPN2 rs478582, 111 developed IA, defined as positivity for GAD, insulin or IA-2 autoantibodies on 2 or more consecutive visits, and 38 IA positive children progressed to T1D. Proportional hazards regression analyses were conducted. There was no association between IA development and any of the gene variants, nor was there evidence of a VDR*PTPN2 interaction. Progression to T1D in IA positive children was associated with the VDR rs2228570 GG genotype (HR: 0.49, 95% CI: 0.26-0.92) and there was an interaction between VDR rs1544410 and PTPN2 rs1893217 (p(interaction)=0.02). In children with the PTPN2 rs1893217 AA genotype, the VDR rs1544410 AA/AG genotype was associated with a decreased risk of T1D (HR: 0.24, 95% CI: 0.11-0.53, p=0.0004), while in children with the PTPN2 rs1893217 GG/GA genotype, the VDR rs1544410 AA/AG genotype was not associated with T1D (HR: 1.32, 95% CI: 0.43-4.06, p=0.62). These findings should be replicated in larger cohorts for confirmation. The interaction between VDR and PTPN2 polymorphisms in the risk of progression to T1D offers insight concerning the role of vitamin D in the etiology of T1D.

Confirmation of novel type 1 diabetes risk loci in families.

AIMS/HYPOTHESIS: Over 50 regions of the genome have been associated with type 1 diabetes risk, mainly using large case/control collections. In a recent genome-wide association (GWA) study, 18 novel susceptibility loci were identified and replicated, including replication evidence from 2,319 families. Here, we, the Type 1 Diabetes Genetics Consortium (T1DGC), aimed to exclude the possibility that any of the 18 loci were false-positives due to population stratification by significantly increasing the statistical power of our family study. METHODS: We genotyped the most disease-predicting single-nucleotide polymorphisms at the 18 susceptibility loci in 3,108 families and used existing genotype data for 2,319 families from the original study, providing 7,013 parent-child trios for analysis. We tested for association using the transmission disequilibrium test. RESULTS: Seventeen of the 18 susceptibility loci reached nominal levels of significance (p < 0.05) in the expanded family collection, with 14q24.1 just falling short (p = 0.055). When we allowed for multiple testing, ten of the 17 nominally significant loci reached the required level of significance (p < 2.8 × 10(-3)). All susceptibility loci had consistent direction of effects with the original study. CONCLUSIONS/INTERPRETATION: The results for the novel GWA study-identified loci are genuine and not due to population stratification. The next step, namely correlation of the most disease-associated genotypes with phenotypes, such as RNA and protein expression analyses for the candidate genes within or near each of the susceptibility regions, can now proceed.

Detection of four diabetes specific autoantibodies in a single radioimmunoassay: an innovative high-throughput approach for autoimmune diabetes screening.

Highly sensitive and specific radioimmunoassays have been validated for autoantibodies reacting with the four major autoantigens identified so far in autoimmune diabetes. However, the analysis of this large number of autoantigens has increased the costs and time necessary for complete autoantibody screenings. Our aim was to demonstrate that it is possible to detect the immunoreactivity against a combination of four different autoantigens by a single assay, this representing a rapid, low-cost first approach to evaluate humoral autoimmunity in diabetes. By using this novel multi-autoantigen radioimmunoassay (MAA), in subsequent steps we analysed 830 sera, 476 of known and 354 of unknown diabetes-specific immunoreactivity, collected from various groups of individuals including type 1 and type 2 diabetes patients, autoantibody-positive patients with a clinical diagnosis of type 2 diabetes (LADA), prediabetic subjects, individuals at risk to develop autoimmune diabetes, siblings of type 1 diabetic patients, coeliac patients and healthy control subjects. All sera reacting with one or more of the four autoantigens by single assays also resulted positive with MAA, as well as eight of 24 type 1 diabetic patients classified initially as autoantibody-negative at disease onset based on single autoantibody assays. In addition, MAA showed 92% sensitivity and 99% specificity by analysing 140 blinded sera from type 1 diabetic patients and control subjects provided in the 2010 Diabetes Autoantibody Standardization Program. MAA is the first combined method also able to evaluate, in addition to glutamic acid decarboxylase (GAD) and tyrosine phosphatase (IA)-2, insulin and islet beta-cell zinc cation efflux transporter (ZnT8) autoantibodies. It appears to be particularly appropriate as a first-line approach for large-scale population-based screenings of anti-islet autoimmunity.

The HLA-B 3906 allele imparts a high risk of diabetes only on specific HLA-DR/DQ haplotypes.

AIMS/HYPOTHESIS: We investigated the risk associated with HLA-B*39 alleles in the context of specific HLA-DR/DQ haplotypes. METHODS: We studied a readily available dataset from the Type 1 Diabetes Genetics Consortium that consists of 2,300 affected sibling pair families genotyped for both HLA alleles and 2,837 single nucleotide polymorphisms across the major histocompatibility complex region. RESULTS: The B*3906 allele significantly enhanced the risk of type 1 diabetes when present on specific HLA-DR/DQ haplotypes (DRB1 0801-DQB1 0402: p = 1.6 × 10(-6), OR 25.4; DRB1 0101-DQB1 0501: p = 4.9 × 10(-5), OR 10.3) but did not enhance the risk of DRB1 0401-DQB1 0302 haplotypes. In addition, the B 3901 allele enhanced risk on the DRB1 1601-DQB1 0502 haplotype (p = 3.7 × 10(-3), OR 7.2). CONCLUSIONS/INTERPRETATION: These associations indicate that the B 39 alleles significantly increase risk when present on specific HLA-DR/DQ haplotypes, and HLA-B typing in concert with specific HLA-DR/DQ genotypes should facilitate genetic prediction of type 1 diabetes, particularly in a research setting.

CHOP deletion does not impact the development of diabetes but suppresses the early production of insulin autoantibody in the NOD mouse.

C/EBP homologous protein (CHOP) has been proposed as a key transcription factor for endoplasmic reticulum (ER) stress-mediated ß-cell death induced by inflammatory cytokines in vitro. However, the contribution of CHOP induction to the pathogenesis of type 1 diabetes is not yet clear. To evaluate the relevance of CHOP in the pathogenesis of type 1 diabetes in vivo, we generated CHOP-deficient non-obese diabetic (NOD.Chop (-/-)) mice. CHOP deficiency did not affect the development of insulitis and diabetes and apoptosis in ß-cells. Interestingly, NOD.Chop (-/-) mice exhibited a delayed appearance of insulin autoantibodies compared to wild-type (wt) mice. Adoptive transfer with the diabetogenic, whole or CD8(+)-depleted splenocytes induced ß-cell apoptosis and the rapid onset of diabetes in the irradiated NOD.Chop (-/-) recipients with similar kinetics as in wt mice. Expression of ER stress-associated genes was not significantly up-regulated in the islets from NOD.Chop (-/-) compared to those from wt mice or NOD-scid mice. These findings suggest that CHOP expression is independent of the development of insulitis and diabetes but might affect the early production of insulin autoantibodies in the NOD mouse.

Kinetics of the post-onset decline in zinc transporter 8 autoantibodies in type 1 diabetic human subjects.

CONTEXT: Zinc transporter 8 (ZnT8) is a newly discovered islet autoantigen in human type 1A diabetes (T1D). OBJECTIVE: The objective was to document changes in ZnT8 autoantibody (ZnT8A) titer and prevalence after onset of disease in relationship to 65 kDa glutamate decarboxylase antibody (GADA) and islet cell antigen antibody (IA2A). DESIGN/PATIENTS: Autoantibody radioimmunoprecipitation assays were performed on sera from three groups: 21 individuals monitored every 3 months from diagnosis for 2.5 yr; 61 individuals monitored at six monthly intervals for 5-12 yr; and a cross-sectional study of 424 patients with T1D of 20-57 yr duration. Circulating C-peptide was determined as an index of residual ß-cell function. RESULTS: ZnT8A titers declined exponentially from clinical onset of T1D with a t(1/2) ranging from 26 to 530 wk, similar to C-peptide (23-300 wk). Life-table analysis of antibody prevalence to 12 yr indicated that ZnT8A measured with either Arg325 or Trp325 probes persisted for a shorter interval than IA2A. Although prevalence of ZnT8A, IA2A, and GADA were comparable at disease onset (70.4 vs. 73.4 vs. 64%), only 6.7% of individuals remained ZnT8A positive after 25 yr compared with 19.5% for IA2A and 25.9% for GADA. Titers of ZnT8A and IA2A in seropositive individuals decreased progressively, whereas GADA remained elevated consistent with periodic reactivation of GADA humoral autoimmunity. CONCLUSIONS: ZnT8 humoral autoreactivity declines rapidly in the first years after disease onset and is less persistent than IA2A or GADA in the longer term. ZnT8A determination may be a useful measure of therapeutic efficacy in the context of immune-based clinical interventions.

Dimorphic histopathology of long-standing childhood-onset diabetes.

AIMS/HYPOTHESIS: Childhood diabetes is thought to usually result from autoimmune beta cell destruction (type 1A) with eventual total loss of beta cells. Analysis of C-peptide in children characterised at diabetes onset for autoantibodies shows heterogeneous preservation of insulin secretion in long-standing diabetes. The aim of this study was to characterise the pancreases of childhood-onset diabetes in order to define the pathological basis of this heterogeneity. METHODS: We evaluated 20 cadaveric organ donor pancreases of childhood-onset long-term patients for disease heterogeneity and obtained corresponding C-peptide measurements. RESULTS: Pancreases from the majority of cadaveric donors contained only insulin-deficient islets (14 of 20). The remaining six patients (30%) had numerous insulin-positive cells within at least some islets, with two different histological patterns. Pattern A (which we would associate with type 1A diabetes) had lobular retention of areas with 'abnormal' beta cells producing the apoptosis inhibitor survivin and HLA class I. In pattern B, 100% of all islets contained normal-appearing but quantitatively reduced beta cells without survivin or HLA class I. CONCLUSIONS/INTERPRETATION: Our data demonstrate that C-peptide secretion in long-standing diabetic patients can be explained by two different patterns of beta cell survival,possibly reflecting different subsets of type 1 diabetes.

rs2476601 T allele (R620W) defines high-risk PTPN22 type I diabetes-associated haplotypes with preliminary evidence for an additional protective haplotype.

Protein tyrosine phosphatase non-receptor type 22 (PTPN22) is the third major locus affecting risk of type I diabetes (T1D), after HLA-DR/DQ and INS. The most associated single-nucleotide polymorphism (SNP), rs2476601, has a C->T variant and results in an arginine (R) to tryptophan (W) amino acid change at position 620. To assess whether this, or other specific variants, are responsible for T1D risk, the Type I Diabetes Genetics Consortium analyzed 28 PTPN22 SNPs in 2295 affected sib-pair (ASP) families. Transmission Disequilibrium Test analyses of haplotypes revealed that all three haplotypes with a T allele at rs2476601 were overtransmitted to affected children, and two of these three haplotypes showed statistically significant overtransmission (P=0.003 to P=5.9E-12). Another haplotype had decreased transmission to affected children (P=3.5E-05). All haplotypes containing the rs2476601 T allele were identical for all SNPs across PTPN22 and only varied at centromeric SNPs. When considering rs2476601 'C' founder chromosomes, a second haplotype (AGGGGC) centromeric of PTPN22 in the C1orf178 region was associated with protection from T1D (odds ratio=0.81, P=0.0005). This novel finding requires replication in independent populations. We conclude the major association of PTPN22 with T1D is likely due to the recognized non-synonymous SNP rs2476601 (R620W).

Insulin2 gene (Ins2) transcription by NOD bone marrow-derived cells does not influence autoimmune diabetes development in NOD-Ins2 knockout mice.

Insulin is a critical autoantigen for the development of autoimmune diabetes in non-obese diabetic (NOD) mice. About 80% of NOD females and 30-40% of NOD males develop diabetes. However, Insulin2 (Ins2) knockout NOD mice develop autoimmune diabetes with complete penetrance in both sexes, at an earlier age, and have stronger autoimmune responses to insulin. The severe diabetes phenotype observed in NOD-Ins2-/- mice suggests that lack of Ins2 expression in the thymus may compromise immunological tolerance to insulin. Insulin is a prototypical tissue specific antigen (TSA) for which tolerance is dependent on expression in thymus and peripheral lymphoid tissues. TSA are naturally expressed by medullary thymic epithelial cells (mTEC), stromal cells in peripheral lymphoid tissues and bone marrow (BM)-derived cells, mainly CD11c(+) dendritic cells. The natural expression of TSA by mTEC and stromal cells has been shown to contribute to self-tolerance. However, it is unclear whether this also applies to BM-derived cells naturally expressing TSA. To address this question, we created BM chimeras and investigated whether reintroducing Ins2 expression solely by NOD BM-derived cells delays diabetes development in NOD-Ins2-/- mice. On follow-up, NOD-Ins2-/- mice receiving Ins2-expressing NOD BM cells developed diabetes at similar rates of those receiving NOD-Ins2-/- BM cells. Diabetes developed in 64% of NOD recipients transplanted with NOD BM and in 47% of NOD mice transplanted with NOD-Ins2-/- BM (P = ns). Thus, NOD-Ins2-/- BM did not worsen diabetes in NOD recipients and Ins2 expression by NOD BM-derived cells did not delay diabetes development in NOD-Ins2-/- mice.

Two novel AIRE mutations in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) among Indians.

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare recessive disorder resulting from mutations in the autoimmune regulator (AIRE) gene. There is no information on AIRE mutations in Indians. In a cross-sectional study, nine patients (eight families), from four referral hospitals in India, were studied for AIRE mutations by direct sequencing. We screened for new mutations in 150 controls by allele-specific PCR. The patients had 1-7 known components of APECED. Three patients had unusual manifestations: presentation with type 1 diabetes; chronic sinusitis and otitis media; and facial dysmorphism. All patients carried homozygous, probably recessive, AIRE mutations. Two unrelated patients from a small in-bred community (Vanika Vaisya) in south India carried an unreported missense mutation, p.V80G, in the N-terminal caspase recruitment domain. Another unique mutation, p.C302X, resulting in a truncated protein with deletion of both zinc-finger domains, was detected in a patient from Gujarat. Neither mutation was detected in controls. Other mutations, previously described in Caucasians, were: 13 base pair deletion (p.C322fsX372) in 4 (38%), and Finn-major (p.R257X) and p.R139X (Sardinian) mutation in one subject each. In conclusion, in this first series of APECED in Indians, we detected AIRE mutations previously reported in Caucasians, as well as unique mutations. Of these, p.V80G is possibly an ancestral mutation in an in-bred community.

Autoimmune polyendocrine syndrome type 1 (APS-1) as a model for understanding autoimmune polyendocrine syndrome type 2 (APS-2).

Autoimmune polyendocrine syndromes type 1 and 2 (APS-1 and APS-2) are diverse in regards to their component diseases and immunologic features of pathogenesis. Animal models and human studies highlight the importance of alleles of HLA (human leukocyte antigen)-like molecules determining tissue specific targeting that with the loss of tolerance leads to organ specific autoimmunity. Knowledge of the syndromes and component diseases allows clinicians to recognize and prevent illness prior to morbidity. With the current understanding of the syndromes, a paradigm for diagnosis, screening and treatment can be established. Once genetically susceptible individuals are identified screening for autoantibodies can be performed. Amongst autoantibody positive individuals, monitoring for physiologic decompensation, with a goal of treating prior to morbidity and in some cases mortality, follows. With continued basic and clinical research, therapies aimed at treating the underlying autoimmunity and disease prevention should become possible.

The frequent and conserved DR3-B8-A1 extended haplotype confers less diabetes risk than other DR3 haplotypes.

AIM: The goal of this study was to develop and implement methodology that would aid in the analysis of extended high-density single nucleotide polymorphism (SNP) major histocompatibility complex (MHC) haplotypes combined with human leucocyte antigen (HLA) alleles in relation to type 1 diabetes risk. METHODS: High-density SNP genotype data (2918 SNPs) across the MHC from the Type 1 Diabetes Genetics Consortium (1240 families), in addition to HLA data, were processed into haplotypes using PedCheck and Merlin, and extended DR3 haplotypes were analysed. RESULTS: With this large dense set of SNPs, the conservation of DR3-B8-A1 (8.1) haplotypes spanned the MHC (>/=99% SNP identity). Forty-seven individuals homozygous for the 8.1 haplotype also shared the same homozygous genotype at four 'sentinel' SNPs (rs2157678 'T', rs3130380 'A', rs3094628 'C' and rs3130352 'T'). Conservation extended from HLA-DQB1 to the telomeric end of the SNP panels (3.4 Mb total). In addition, we found that the 8.1 haplotype is associated with lower risk than other DR3 haplotypes by both haplotypic and genotypic analyses [haplotype: p = 0.009, odds ratio (OR) = 0.65; genotype: p = 6.3 x 10(-5), OR = 0.27]. The 8.1 haplotype (from genotypic analyses) is associated with lower risk than the high-risk DR3-B18-A30 haplotype (p = 0.01, OR = 0.23), but the DR3-B18-A30 haplotype did not differ from other non-8.1 DR3 haplotypes relative to diabetes association. CONCLUSION: The 8.1 haplotype demonstrates extreme conservation (>3.4 Mb) and is associated with significantly lower risk for type 1 diabetes than other DR3 haplotypes.

Conserved epitopes in the protein tyrosine phosphatase family of diabetes autoantigens.

IA2 and phogrin are important targets of humoral and cell-mediated autoimmunity in type 1 diabetes in man. They belong to a conserved subfamily of transmembrane protein tyrosine phosphatases (PTPs) associated with the regulatory pathway of secretion. To examine potential cross-reactivity between PTP family members we tested sera from T1D patients for reactivity to IA2, and the Drosophila (FLYDA) and C. elegans (IDA) orthologs using radioimmunoprecipitation assays of (35)S Met-labeled in vitro translated products of the cytosolic domains of these proteins. Approximately 80% of sera reacted with at least one probe. Of these, 82.5% showed reactivity to human IA2, 74.1% to FLYDA, and 33.7% to IDA. The majority of sera that bound FLYDA and/or IDA also recognized IA2. This raises the possibility that in some cases reactivity to IA2 may have arisen by molecular mimicry.

Differential effects of DRB1*0301 and DQA1*0501-DQB1*0201 on the activation and progression of islet cell autoimmunity.

Autoimmune diabetes shows extreme variation in age of onset and clinical presentation, although most studies have been done in children with the most severe subtype. Disease risk is strongly associated with HLA-DRB1*0301-DQA1*0501-DQB1*0201 (DR3-DQ2), but it has not been possible to separate the effects of the DR and DQ alleles. We have identified a large Bedouin kindred in which a high prevalence of islet autoimmunity is associated with two different DR3 haplotypes, one carrying the usual DQ2 and the other carrying DQA1*0102-DQB1*0502 (DQ5). Results of prospective follow-up studies indicate that DR3 is associated with the initial activation of islet autoimmunity whereas DQ2 is associated with early-onset and severe clinical disease. The association signals map to a 350-kb interval, thus implicating primary effects for DR3 and DQ2. Overall, our results emphasize the importance of prospective genetic studies that examine the full range of variation in the initiation, progression and expression of autoimmune disease.

Cellular and molecular pathogenesis of type 1A diabetes.

Type 1A diabetes is an organ-specific autoimmune disease resulting from destruction of insulin-producing pancreatic beta-cells. The main susceptibility genes code for polymorphic HLA molecules and in particular alleles of class II MHC genes (DR, DQ and DP). Polymorphisms of individual genes outside the MHC also contribute to diabetes risk but recent evidence suggests that there are additional non-HLA genes determining susceptibility linked to the MHC. It is now possible using genetic and autoantibody assays to predict the development of type 1A diabetes in the majority of individuals, and trials of diabetes prevention are underway.

Long-term prevention of diabetes and marked suppression of insulin autoantibodies and insulitis in mice lacking native insulin B9-23 sequence.

We analyzed double native insulin gene knockout NOD mice with a mutated (B16:alanine) proinsulin transgene at multiple ages for the development of insulin autoantibodies, insulitis, and diabetes. In contrast to mice with at least one copy of a native insulin gene that expressed insulin antibodies, only 2 out of 21 (10%) double native insulin gene knockout mice with a mutated insulin transgene developed insulin autoantibodies. Of 21 double insulin knockout mice sacrificed between 10 to 48 weeks of age, only 5 showed minimal insulitis versus 100% of wild-type NOD and more than 90% of insulin 1 knockout mice. Consistent with robust suppression of insulin autoantibodies and insulitis, no double insulin knockout mice developed diabetes. In that the B9-23 peptide with B16A is an altered peptide ligand inducing Th2 responses, we analyzed transfer of splenocytes into NOD.SCID mice. There was no evidence for regulatory T cells able to inhibit transfer of diabetes by diabetogenic NOD splenocytes. Insulin peptide B9-23 is likely a crucial target for initiation of islet autoimmunity and further mutation of the sequence will be tested to attempt to eliminate all anti-islet autoimmunity.

Evidence of a selective epitope loss of anti-transglutaminase immunoreactivity in gluten-free diet celiac sera: a new tool to distinguish disease-specific immunoreactivities.

The aim of the present study was to evaluate the epitope specific humoral human tissue transglutaminase (tTG) immunoreactivity against 3 different human recombinant tTG constructs [(full-length tTG (a.a. 1-687), tTG (a.a. 227-687); tTG (a.a. 473-687)] before and after the introduction of a gluten-free diet (GFD). To this end, sera from 64 celiac disease (CD) subjects on a gluten-containing diet (44 f, 20 m) and after 0.6 +/- 0.3 years and 2.1 +/- 1.3 years of GFD were studied using a quantitative radioimmunoprecipitation assay. All 64 CD patients at diagnosis were full-length anti-tTG (a.a. 1-687)Ab positive. These Abs significantly decreased in frequency and titer after 6 months and 2 years of GFD. However, at low titers, 64.1% (41/64) of CD patients were still fl-tTG (a.a. 1-687)Ab positive after 2 years of GFD. At disease diagnosis, 70.3% (45/64) of the CD patients had Abs directed against fragments (227-687) and/or (473-687) of the tTG protein. This percentage, after 2 years of GFD, significantly decreased to 18.7%, whereas almost 50% of GFD patients had no tTG (227-687) and tTG (473-687) fragment reactivity, but only persistent, low-titer full-length tTG (1-687)Abs. We suggest that the selective loss of immunoreactivity against tTG (227-687) and tTG (473-687) fragments in CD patients with a GFD, could be due to quantitative decrease of autoreactivity driven by tTG-gliadin interaction underlying celiac disease pathogenesis.

A new model of insulin-deficient diabetes: male NOD mice with a single copy of Ins1 and no Ins2.

AIMS/HYPOTHESIS: We describe a novel model of insulin-deficient diabetes with a single copy of the gene encoding insulin 1 (Ins1) and no gene encoding insulin 2 (Ins2). MATERIALS AND METHODS: We constructed five lines of mice: mice with two copies of Ins1 (NOD( Ins1+/+,Ins2-/-)), mice with a single copy of Ins1 (NOD( Ins1+/-,Ins2-/-)), mice with two copies of Ins2 (NOD( Ins1-/-,Ins2+/+)), mice with a single copy of Ins2 (NOD( Ins1-/-,Ins2+/-)) and NOD( Ins1+/-,Ins2-/-) mice with a transgene encoding B16:Ala proinsulin. RESULTS: By 10 weeks of age, all male NOD( Ins1+/-,Ins2-/-) mice were diabetic, whereas all female NOD( Ins1+/-,Ins2-/-) were not diabetic (p < 0.0001). In contrast, neither male nor female NOD( Ins1-/-,Ins2+/-) with a single copy of Ins2 (rather than single copy of Ins1) developed early diabetes and no mice with two copies of either gene developed early diabetes. Islets of the diabetic male NOD( Ins1+/-,Ins2-/-) at this early age had no lymphocyte infiltration. Instead there was heterogeneous (between islet cells) weak staining for insulin. Although only male NOD( Ins1+/-,Ins2-/-) mice developed diabetes, both male and female NOD( Ins1+/-,Ins2-/-) mice had markedly decreased insulin content. In NOD( Ins1+/+,Ins2-/-), there was also a significant decrease in insulin content, whereas NOD( Ins1-/-,Ins2+/+) mice, and even NOD( Ins1-/-,Ins2+/-) mice, were normal. Male NOD( Ins1+/-,Ins2-/-) mice were completely rescued from diabetes by introduction of a transgene encoding proinsulin. On i.p. insulin tolerance testing, male mice had insulin resistance compared with female mice. CONCLUSIONS/INTERPRETATION: These results suggest that Ins1 is a 'defective gene' relative to Ins2, and that the mouse lines created provide a novel model of sex-dimorphic insulin-deficient diabetes.

Initial results of screening of nondiabetic organ donors for expression of islet autoantibodies.

CONTEXT: Type 1A diabetes is characterized by a long prodromal phase during which autoantibodies to islet antigens are present. Nevertheless, we lack data on the pancreatic pathology of subjects who are positive for islet autoantibodies (to islet autoantigens GAD65, insulin, and ICA512). OBJECTIVE: In this manuscript, we describe a novel strategy in obtaining pancreata and pancreatic lymph nodes from islet autoantibody-positive organ donors that involves careful coordination among the laboratory and the organ donor provider organization. DESIGN: We developed a rapid screening protocol for islet autoantibodies measurement of organ donors to allow identification of positive subjects before organ harvesting. In this way we were able to obtain pancreata and pancreatic lymph nodes from subjects with and without islet autoimmunity. SETTING: The organ donors used in this study were obtained from the general community. SUBJECTS: The population studied consisted of 112 organ donors (age range 1 month to 86 yr, mean age 39 yr). MAIN OUTCOME MEASURE: The main outcome measure of this study consisted of evaluating the pancreatic histology and identify T cells autoreactive for islet antigens in the pancreatic lymph nodes. RESULTS: To date we have identified three positive subjects and obtained the pancreas for histological evaluation from one of the autoantibody-positive donors who expressed ICA512 autoantibodies. Although this subject did not exhibit insulitis, lymphocytes derived from pancreatic lymph nodes reacted to the islet antigen phogrin. CONCLUSION: In summary, these results indicate that it is possible to screen organ donors in real time for antiislet antibodies, characterize pancreatic histology, and obtain viable T cells for immunological studies.

Insulin as a primary autoantigen for type 1A diabetes.

Type 1A diabetes mellitus is caused by specific and progressive autoimmune destruction of the beta cells in the islets of Langerhans whereas the other cell types in the islet (alpha, delta, and PP) are spared. The autoantigens of Type 1A diabetes may be divided into subgroups based on their tissue distributions: Beta-cell-specific antigens like insulin, insulin derivatives, and IGRP (Islet-specific Glucose-6-phosphatase catalytic subunit Related Peptide); neurendocrine antigens such as carboxypeptidase H, insulinoma-associated antigen (IA-2), glutamic acid decarboxylase (GAD65), and carboxypeptidase E; and those expressed ubiquitously like heat shock protein 60 (a putative autoantigen for type 1 diabetes). This review will focus specifically on insulin as a primary autoantigen, an essential target for disease, in type 1A diabetes mellitus. In particular, immunization with insulin peptide B:9-23 can be used to induce insulin autoantibodies and diabetes in animal models or used to prevent diabetes. Genetic manipulation of the insulin 1 and 2 genes reciprocally alters development of diabetes in the NOD mouse, and insulin gene polymorphisms are important determinants of childhood diabetes. We are pursuing the hypothesis that insulin is a primary autoantigen for type 1 diabetes, and thus the pathogenesis of the disease relates to specific recognition of one or more peptides.