Islet Antigens Research Articles

1482-P: Effect of Age on Diabetes-Specific Autoantibodies in a Large Laboratory-Based Cohort

Type 1 diabetes mellitus (T1DM) can occur at any age, the presence of diabetes related autoantibodies predicts increased risk of disease and supports an autoimmune etiology for T1DM. Since 2017, Mayo Clinic Laboratories has been offering a comprehensive type 1 diabetes autoantibody evaluation (DM1Eval) which includes testing for 4 autoantibodies targeting glutamic acid decarboxylase autoantibodies (GAD), protein tyrosine phosphatase-like islet antigen 2 (IA-2), insulin (IAA), and zinc transporter 8 protein (ZnT8). The aim of this study was to determine the frequency of individual antibodies and antibody clusters (2, 3 or 4) stratified into 4 ages groups (children 0-17, young adult 18-35, middle aged 36-55 and older >55 years). Over a 30 month period (June 2017-Nov 2019) the DM1Eval was performed on 6,446 samples. At least 1 autoantibody was found in 3596 (56%) of all samples: 68% of children, 49% of young adults, 40% of middle aged and 41% of older adults. In patients with at least 1 antibody positive, GAD 65 antibodies were the most common in all age groups followed by ZnT8 in those <36 years or IAA antibody in those 36 and older older (Figure). The frequencies of IA2 and ZnT8 antibodies dropped significantly with increasing age strata. Autoantibody clusters of 3 or 4 antibodies were more frequently encountered in younger patients (41% of pediatric and 27% of young adult patients in contrast to just 12% in middle and older age groups). Disclosure A.R. Dahl: None. S. Pittock: None. A. McKeon: None. J. Foster: None. J. Mills: None.

254-OR: Islet Autoimmunity Is Highly Prevalent and Associated with Diminished Beta-Cell Function in Patients with Type 2 Diabetes (T2D) in the GRADE Study

We hypothesized that islet autoimmunity, hitherto considered the pathophysiologic basis of type 1 diabetes (T1D) and latent autoimmune diabetes of adults (LADA), could contribute to ß cell dysfunction in patients with type 2 diabetes (T2D). To evaluate this question, the Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness (GRADE) Study - Beta Cell Ancillary Study Network measured humoral islet autoimmunity (autoantibodies against 65 kDa glutamic acid decarboxylase (GAD65-Ab), islet autoantigen-2 (IA2-Ab) and zinc transporter-8 (ZnT8-Ab)) in 392 participants (age 57.2 ± 10.1 y; BMI 33.5 ± 6.2 kg/m2; diabetes duration 4.0 ± 3.0 y; HbA1c 7.5 ± 0.5 %; on metformin as the sole glucose-lowering medication), and cellular islet autoimmunity (T cell autoreactivity against a broad range of islet antigens) in 322 of the same participants. 41.4% had evidence of cellular islet autoimmunity and 13.5% had evidence of humoral islet autoimmunity, but only 5.4% had both. T cell autoreactivity to islet antigens, but not autoantibody-positivity, was associated with diminished ß cell function, as assessed by the ratio of incremental area under the curve (iAUC) of C-peptide to iAUC of glucose during 0-120 min of an OGTT (ß = -0.1403; se = 0.0612; p = 0.0219) or ∆C-peptide/∆glucose during 0-30 min of an OGTT (ß = -0.2113; se = 0.0728; p = 0.0037), adjusted for insulin sensitivity. T cell positive participants also had higher fasting plasma glucose (p = 0.045) and HbA1c (p = 0.001) than T cell negative participants. These findings indicate that islet autoimmunity in T2D patients is far more prevalent than previously recognized; T cell mediated islet autoimmunity is associated with diminished ß cell function. Disclosure B. Brooks-Worrell: None. C.S. Hampe: None. E.V. Gonzalez: None. B.M. Palomino: None. S.Z. Zangeneh: None. K. Utzschneider: Other Relationship; Self; Medtronic. S.E. Kahn: Advisory Panel; Self; Boehringer Ingelheim International GmbH, Eli Lilly and Company, Intarcia Therapeutics, Janssen Scientific Affairs, LLC., Merck & Co., Inc., Novo Nordisk A/S, Pfizer Inc. M.E. Larkin: None. M.L. Johnson: Consultant; Self; Jaeb Center for Health Research. Research Support; Self; Abbott, Dexcom, Inc., Insulet Corporation, JDRF, Lilly Diabetes, Medtronic, National Institute of Diabetes and Digestive and Kidney Diseases, Novo Nordisk Inc. K.J. Mather: Research Support; Self; Abbott, Merck & Co., Inc., Novo Nordisk Inc., Sanofi. N. Younes: None. N. Rasouli: Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Novo Nordisk Inc. Research Support; Self; Allergan plc., Novo Nordisk Inc. C. Desouza: Consultant; Self; AstraZeneca, Bayer AG, Novo Nordisk A/S. R.M. Cohen: Stock/Shareholder; Self; Bristol-Myers Squibb. J.Y. Park: None. H. Florez: None. W. Valencia: None. A. Shojaie: None. J.P. Palmer: None. A. Balasubramanyam: None. Funding National Institutes of Health (R01DK104832, U01DK098246)

287-OR: TCR/HLA Humanized Mice Reveal Reduced Tolerance and Increased Immunogenicity of Posttranslationally Modified GAD65 Epitope

T cells specific for post-translationally modified (PTM) islet antigens have been implicated as critical players in the development of type 1 diabetes. T cells reactive to the deamidated version of glutamic acid decarboxylase 65 (GAD65) 115-127 epitope accumulate in peripheral blood of patients as they progress to disease. However, knowledge regarding the development, activation, differentiation and islet recruitment of PTM reactive T cells is limited. Using retroviral gene delivery, we have developed a humanized TCR/HLA mouse model to assess the in vivo function of human TCRs reactive to either the wild type (GADWT) or the deamidated (GAD120E) GAD65115-127 epitope. Both TCRs supported efficient thymic selection; however, fewer regulatory T cells developed in mice expressing the PTM reactive TCR, which was partially rescued by the thymic delivery of GAD120E peptide. Immunization of immune sufficient polyclonal DR4.NOD mice with GAD120E/CFA elicited a stronger response compared to GADWT/CFA, confirming that tolerance to the wild type autoantigen is more robust. Interestingly, while islet infiltration in GAD120E single TCR mice was dependent on priming with the cognate PTM peptide, GADWT-TCR T cells could be induced to infiltrate islets after priming with either GADWT or GAD120E peptide, despite the vastly different functional affinity (EC50, GADWT: 0.047μM vs. GAD120E: ≥1.4μM). These findings suggest that the development and expansion of GAD65 PTM reactive CD4+ T cells are less restricted in peripheral lymphoid organs, but their recruitment to the tissue site is dependent on the availability of PTM antigen. Disclosure Y. Jing: None. Y. Kong: None. J. McGinty: None. G. Blahnik-Fagan: None. M. Bettini: None. E.A. James: None. M. Bettini: None. Funding National Institutes of Health (R01AI125301)

201-LB: NKG2D Signaling within Pancreatic Islets Reduces NOD Diabetes and Is Associated with CD8+ Central Memory T-Cell Generation

Type 1 diabetes is an autoimmune disease in which the pancreatic β islet cells are destroyed. The main drivers of type 1 diabetes are islet-specific T cells. These cells must escape a myriad of tolerance mechanisms that control their activation in healthy individuals. Understanding these mechanisms is critical to developing better strategies to inhibit the disease. One pathway implicated in this process is NKG2D signaling. However, the importance of NKG2D to diabetes pathogenesis is unclear owing to conflicting results from studies in which NKG2D signaling was inhibited globally. Our previous studies indicate that these inconsistent findings are due to differential effects of NKG2D signaling in response to islet antigen and the microbiota. Therefore, new experimental approaches are required to determine the roles of NKG2D during diabetes development. To this end, we generated two novel mouse models. These are transgenic NOD mice that have enhanced NKG2D ligand expression in β cells (RIP-RAE1ε mice), and NOD mice lacking expression of the NKG2D ligand endogenously expressed in islets, H60a. We found that the RIP-RAE1ε mice and H60a-deficient mice had decreased and increased diabetes, respectively. These data demonstrate that increasing NKG2D signaling within the pancreas protects, whereas eliminating NKG2D signaling enhances, NOD diabetes. Further, we show that the NKG2D-mediated protection is associated with an increase in CD8+ central memory T cells (Tcm) in vivo, which correlates with NKG2D signaling-induced generation of both mouse and human CD8+ central memory T cells in vitro, and that CD8+ Tcm protect against diabetes in the NOD.SCID adoptive transfer model. Taken together, these data indicate that NKG2D signaling protects against diabetes by enhancing the generation of a protective CD8+ Tcm population. Disclosure A. Trembath: None. N. Sharma: None. I.C. Gerling: None. C.E. Mathews: None. M.A. Markiewicz: Consultant; Self; Johnson & Johnson. Funding American Diabetes Association (1-12-JF-41 to M.A.M.); National Institutes of Health (P30GM103326, P30CA168524, UC4DK104167, UC4DK104155, U54HD090216, P30DK020579, P30GM122731); JDRF (5-SRA-2018-557-Q-R, 17-2012-595); The Leona M. and Harry B. Helmsley Charitable Trust (2018PG-T1D053); American Association of Immunologists

SAT-688 Rare Case of 48 XXYY Syndrome with Suspected Type 1 Diabetes Mellitus

BACKGROUND: 48 XXYY syndrome is a rare aneuploidy characterized by the presence of an extra X and Y chromosome in males. Patients share features of Klinefelter syndrome such as tall stature, hypogonadism, congenital malformations and neurocognitive issues. Hypogonadism may cause abdominal adiposity hence increasing risk of insulin resistance and type 2 diabetes mellitus (DM). Klinefelter syndrome has been associated with certain autoimmune diseases however there is no autoimmune disease link described with XXYY syndrome. We present a patient with XXYY polysomy with insulin requiring DM.Clinical Case: A 26-year-old intellectually disabled male with history of XXYY polysomy presented with seizures and was evaluated for DM management. At age 18, he was noted to have hyperglycemia while undergoing dental extractions for brittle enamel leading to the diagnosis of DM. He was initiated on oral medications for a short period of time and transitioned to insulin due to significant hyperglycemia. Endocrine evaluation at the time also revealed hypergonadotropic hypogonadism and evaluation for Klinefelter syndrome revealed 48 XXYY aneuploidy.Patient’s history was significant for poorly controlled hyperglycemia with HbA1C ranging in 12–14% range in the last few years. History was negative for diabetic ketoacidosis (DKA) as per his primary endocrinologist, despite being noncompliant with his insulin therapy. History was negative for retinopathy, nephropathy or macrovascular complications, although he did have distal extremity paresthesia. On exam, he was noted to be edentulous with tall stature, BMI 21.7, facial dysmorphism, pes planus and 5th-digit clinodactyly bilaterally. Family history was positive for type 2 DM in father and prediabetes in mother.He presented with seizures and was diagnosed with brain abscess. Hyperglycemia was initially managed with IV insulin, followed by basal/bolus therapy. Fasting labs 20 hours after receiving insulin glargine showed glucose of 284 mg/dL, C-peptide 0.6 ng/mL (ref range: 0.8–3.5), proinsulin less than 1.6 pmol/L (less than 8.0), insulin 4 uIU/mL (3–19) suggestive of type 1 DM. Anti-GAD65 and anti-ICA antibody levels were negative. Additional antibody evaluation for type 1 DM (islet antigen 2, insulin autoantibody, micro-insulin and zinc transporter 8) is currently pending at the time of writing.Conclusion: Prevalence of XXYY syndrome is 1:18 000–1:40 000 in males. There are few case reports describing the association of type 2 DM with this syndrome. Our patient’s low BMI, low insulin and C-peptide with hyperglycemia indicate type 1 DM, although the absence of DKA in the setting of noncompliance suggests residual beta cell function or maturity onset diabetes of the young (MODY). Neither T1DM nor MODY has been reported with 48XXYY previously. Clinicians should be aware of this association as it has implications in terms of management of DM.

Allogeneic bone marrow derived mesenchymal stem cells outperform the autologous in modulating dendritic cells isolated from type 1 diabetic patients

Background & Aim Dendritic cells (DCs) have been implicated in the pathogenesis of type 1 diabetes mellitus (T1DM) and have potential as immunotherapeutic agents. The inhibition of DCs profile and function is part of the multi-level immunomodulatory properties displayed by human Mesenchymal Stem Cells (MSCs). Due to their potent immunoregulatory and immunomodulatory functions, MSCs have emerged as a therapeutic regimen in the management of many diseases that have no effective treatment, including T1DM. It has been shown that in T1DM patients DCs respond in terms of maturation, activation, and phenotype when co-cultured with autologous and allogeneic Bone Marrow derived MSCs (BM-MSC). In the recent study, the effect of autologous BM-MSCs in comparison with the allogeneic BM-MSCs co-cultured with monocyte-derived DCs isolated from TIDM patients was investigated for the first time. Methods, Results & Conclusion Methods Autologous and allogeneic BM-MSCs were isolated from healthy donors and T1DM patients. Then, morphology and surface markers expression were analyzed. Mature DCs (mDCs) were differentiated from CD14+ cells, obtained from newly diagnosed T1DM patients, pulsed with antigen Glutamic Acid Decarboxylase (GAD65) and co-cultured with BM-MSCs. the expression of co-stimulatory molecules and maturation markers were evaluated by flow cytometery. The level of anti-inflammatory cytokines was measured by ELISA. Autologous CD14- cells and GAD65 pulsed mDCs were co-cultured and IFN-γ ELISPOT responses were performed. Secreted level of IL-17 was measured Result autologous and allogeneic BM-MSCs have a comparable effect on GAD65 pulsed mature mDCs in terms of phenotype and maturation marker expression. Interestingly, the secretion levels of (IL-10, IL-6 and TGF-B) increased significantly in the allogeneic BM-MSCs when co-cultured with GAD65 pulsed mDCs. GAD65 pulsed-mDCs/T-cells showed decreased IFN-γ production when co-cultured with BM-MSCs. Moreover, the level of IL-17 secretion declined significantly in the allogeneic BM-MSCs compared to the autologous cells. Conclusion This research demonstrated in vitro the potent immunomodulatory effect of allogeneic BM-MSCs on pancreatic islet antigen specific T-Cells in newly-diagnosed T1DM patients through the induction of DCs’ tolerogenic function. These DCs can contribute to the suppressing T-cell mediated immunity and the promotion of anti-inflammatory responses exerted by BM-MSCs.

Generation of islet antigen-specific engineered Treg for use in T1D therapy via homology-directed gene editing of conventional CD4+ T cells

Abstract Adoptive transfer of regulatory T cells (Treg) is therapeutic in T1D mouse models. Notably, Treg specific for pancreatic islets are more potent than polyclonal Treg in blocking disease. However, the frequency of antigen-specific Treg is extremely low and ex vivo expansion has the potential to destabilize Treg leading to an effector phenotype. Here, we developed methods to generate durable, antigen-specific engineered (ed)Treg from primary human CD4+ T cells using a combination of lentiviral TCR transduction and FOXP3 homology-directed repair (HDR)-editing. Using TCRs derived from clonally expanded CD4+ T cells in T1D, we generated islet-specific edTreg that exhibit a Treg-like phenotype. Islet-specific edTreg effectively suppress proliferation and cytokine production by islet-specific effector T cells (Teff). Notably, edTreg suppress Teff recognizing the identical peptide as well as bystander Teff recognizing alternative islet antigens. Consistent with this, islet-specific edTreg suppress polyclonal islet-specific T cells derived from PBMC. Further, edTreg expressing TCR with high avidity have superior suppressive capacity to those expressing TCR with low avidity. To directly assess the capacity of edTreg to modulate T1D in vivo, we established an identical HDR-editing strategy in islet-specific murine cells. Adoptively transferred islet-specific mu-edTreg homed to the pancreas and blocked diabetes triggered by islet-specific Teff in recipient mice. Collectively, our approach enables the production of edTreg specific to pancreatic islets with the capacity to efficiently suppress islet specific responses. This approach has the capacity to deliver targeted islet specific therapy to treat or prevent T1D.

Detection and analysis of glucose metabolism-related genes in childhood diabetes using targeted next-generation sequencing: In pediatric population-a hospital-based study.

The aim of the present study was to explore the genetic causes of antibody-negative diabetes and investigate its characteristics. A total of 64 patients with new-onset diabetes (>6 m, <16 y) were identified and their initial clinical characteristics were analyzed. Of which, 32 cases with autoantibody-negative diabetes (male, 16 cases; female, 16 cases) were screened for auto-antibodies, including islet cell antibody, glutamic acid decarboxylase antibody and islet antigen-2, which were negative, and fasting C-peptide was ≥0.3 ng/ml. Peripheral blood DNA was extracted from the subjects and their parents for high-throughput sequencing of glucose metabolism-related genes. The group with the pathogenic variation was used as the experimental group. The control group comprised 32 cases of type 1 diabetes (T1D). Their baseline clinical characteristics were determined and statistically analyzed. Out of the 32 antibody-negative diabetes cases, 21 had possible related mutations. There were 2 HNF1B missense mutations, 1 GCK missense mutation and 1 de novo KCNJ11 missense mutation. GCGR c.118G>A p.G40S was present in patients with type 2 DM (T2DM); the locus is associated with T2DM susceptibility in China. An LIPC frameshift mutation was identified, which had not been previously reported; the gene was found to markedly affect protein function and be associated with glucose and lipid metabolism. It was concluded that children with antibody-negative T1D have monogenic diabetes. The present findings shed light on the etiology and mechanism of antibody-negative diabetes, which will enable the comprehensive analysis of antibody-negative diabetes genotypes and phenotypes and further help improved precision treatment.

Increased islet antigen-specific regulatory and effector CD4+ T cells in healthy individuals with the type 1 diabetes-protective haplotype.

The DRB1*15:01-DQB1*06:02 (DR1501-DQ6) haplotype is linked to dominant protection from type 1 diabetes, but the cellular mechanism for this association is unclear. To address this question, we identified multiple DR1501- and DQ6-restricted glutamate decarboxylase 65 (GAD65) and islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP)-specific T cell epitopes. Three of the DR1501/DQ6-restricted epitopes identified were previously reported to be restricted by DRB1*04:01/DRB1*03:01/DQB1*03:02. We also used specific class II tetramer reagents to assess T cell frequencies. Our results indicated that GAD65- and IGRP-specific effector and CD25+CD127-FOXP3+ regulatory CD4+ T cells were present at higher frequencies in individuals with the protective haplotype than those with susceptible or neutral haplotypes. We further confirmed higher frequencies of islet antigen-specific effector and regulatory CD4+ T cells in DR1501-DQ6 individuals through a CD154/CD137 up-regulation assay. DR1501-restricted effector T cells were capable of producing interferon-γ (IFN-γ) and interleukin-4 (IL-4) but were more likely to produce IL-10 compared with effectors from individuals with susceptible haplotypes. To evaluate their capacity for antigen-specific regulatory activity, we cloned GAD65 and IGRP epitope-specific regulatory T cells. We showed that these regulatory T cells suppressed DR1501-restricted GAD65- and IGRP-specific effectors and DQB1*03:02-restricted GAD65-specific effectors in an antigen-specific fashion. In total, these results suggest that the protective DR1501-DQ6 haplotype confers protection through increased frequencies of islet-specific IL-10-producing T effectors and CD25+CD127-FOXP3+ regulatory T cells.

Identification of a subgroup of black South Africans with type 1 diabetes who are older at diagnosis but have lower levels of glutamic acid decarboxylase and islet antigen 2 autoantibodies.

To compare the age at diagnosis and prevalence of islet autoantibody [glutamic acid decarboxylase (65kDa) 65 and islet antigen 2] positivity in black and white participants with type 1 diabetes in South Africa, and to analyse the relationship between age at diagnosis and the presence of autoantibodies. Participants were recruited from diabetes outpatient departments and autoantibodies to glutamic acid decarboxylase (65kDa) and islet antigen 2 were measured by enzyme-linked immunosorbent assay. We recruited 472 (353 black and 119 white) participants with type 1 diabetes. Age at diagnosis of diabetes was later in black (19.7±10.5) than in white participants (12.7±10.8years; P<0.001) with a median (interquartile range) disease duration of 5.0 (2.0-10.0) and 8.5 (4.0-20.0) years (P<0.001), respectively. An older age at diagnosis (≥21years) was more frequent in black (152 of 340, 45%) than in white participants (24 of 116, 21%; P<0.001). The prevalence of islet antigen 2 autoantibodies was 19% (66/352) in black and 41% in white participants (48/118; P<0.001). There was no significant difference in glutamic acid decarboxylase (65kDa) autoantibody positivity between black (212/353, 60%) and white participants (77/117, 66%; P=0.269). In black, but not white, participants the prevalence of both glutamic acid decarboxylase (65kDa) and islet antigen 2 autoantibody positivity was significantly lower in participants diagnosed at age≥21years (P<0.001 for both comparisons). The older age at diagnosis, lower prevalence of islet antigen 2 autoantibodies and a distinct subgroup of participants with type 1 diabetes with age at diagnosis of >20years in the black compared to white population suggest a difference in the immunological aetiology of type 1 diabetes in these two population groups.

Clinical and genetic correlates of islet-autoimmune signatures in juvenile-onset type 1 diabetes

Aims/hypothesisHeterogeneity in individuals with type 1 diabetes has become more generally appreciated, but has not yet been extensively and systematically characterised. Here, we aimed to characterise type 1 diabetes heterogeneity by creating immunological, genetic and clinical profiles for individuals with juvenile-onset type 1 diabetes in a cross-sectional study.MethodsParticipants were HLA-genotyped to determine HLA-DR-DQ risk, and SNP-genotyped to generate a non-HLA genetic risk score (GRS) based on 93 type 1 diabetes-associated SNP variants outside the MHC region. Islet autoimmunity was assessed as T cell proliferation upon stimulation with the beta cell antigens GAD65, islet antigen-2 (IA-2), preproinsulin (PPI) and defective ribosomal product of the insulin gene (INS-DRIP). Clinical parameters were collected retrospectively.ResultsOf 80 individuals, 67 had proliferation responses to one or more islet antigens, with vast differences in the extent of proliferation. Based on the multitude and amplitude of the proliferation responses, individuals were clustered into non-, intermediate and high responders. High responders could not be characterised entirely by enrichment for the highest risk HLA-DR3-DQ2/DR4-DQ8 genotype. However, high responders did have a significantly higher non-HLA GRS. Clinically, high T cell responses to beta cell antigens did not reflect in worsened glycaemic control, increased complications, development of associated autoimmunity or younger age at disease onset. The number of beta cell antigens that an individual responded to increased with disease duration, pointing to chronic islet autoimmunity and epitope spreading.Conclusions/interpretationCollectively, these data provide new insights into type 1 diabetes disease heterogeneity and highlight the importance of stratifying patients on the basis of their genetic and autoimmune signatures for immunotherapy and personalised disease management.

Clinical features, biochemistry and HLA-DRB1 status in children and adolescents with diabetes in Dhaka, Bangladesh

AimsLittle information is published on diabetes in young people in Bangladesh. We aimed to investigate the demographic, clinical, and biochemical features, and HLA-DRB1 alleles in new cases of diabetes affecting Bangladeshi children and adolescents <22 years of age. MethodsThe study was conducted at Bangladesh Institute of Research and Rehabilitation of Diabetes, Endocrine and Metabolic Disorders (BIRDEM) in Dhaka. One hundred subjects aged <22 years at diagnosis were enrolled. Demographic characteristics, clinical information, biochemical parameters (blood glucose, HbA1c, C-peptide, and autoantibodies against glutamic acid decarboxylase 65 (GADA) and islet antigen-2 (IA-2A) were measured. High-resolution DNA genotyping was performed for HLA-DRB1. ResultsEighty-four subjects were clinically diagnosed as type 1 diabetes (T1D), seven as type 2 diabetes (T2D), and nine as fibrocalculous pancreatic disease (FCPD). Of the 84 with T1D, 37 (44%) were males and 47 (56%) females, with median age at diagnosis 13 years (y) (range 1.6–21.7) and peak age at onset 12–15 years. 85% of subjects were assessed within one month of diagnosis and all within eleven months. For subjects diagnosed with T1D, mean C-peptide was 0.46 ± 0.22 nmol/L (1.40 ± 0.59 ng/mL), with 9 (10.7%) IA-2A positive, 22 (26%) GADA positive, and 5 (6%) positive for both autoantibodies. Analysis of HLA-DRB1 genotypes revealed locus-level T1D association (p = 6.0E−05); DRB1*04:01 appeared predisposing (p < 3.0E−06), and DRB1*14:01 appeared protective (p = 1.7E−02). ConclusionsAtypical forms of T1D appear to be more common in young people in Bangladesh than in European populations. This will be helpful in guiding more specific assessment at onset and potentially, expanding treatment options.

Proinsulin peptide promotes autoimmune diabetes in a novel HLA-DR3-DQ2-transgenic murine model of spontaneous disease

Aims/hypothesisThe molecular basis for the pathological impact of specific HLA molecules on autoimmune diseases such as type 1 diabetes remains unclear. Recent natural history studies in children have indicated a link between specific HLA genotypes and the first antigenic target against which immune responses develop. We set out to examine this link in vivo by exploring the diabetogenicity of islet antigens on the background of a common diabetes-associated HLA haplotype.MethodsWe generated a novel HLA-transgenic mouse model that expresses high-risk genes for type 1 diabetes (DRB1*03:01-DQA1*05:01-DQB1*02:01) as well as human CD80 under the rat insulin promoter and human CD4, on a C57BL/6 background. Adjuvanted antigen priming was used to reveal the diabetogenicity of candidate antigens and peptides.ResultsHLA-DR3-DQ2+huCD4+IA/IE−/−RIP.B7.1+ mice spontaneously developed autoimmune diabetes (incidence 46% by 35 weeks of age), accompanied by numerous hallmarks of human type 1 diabetes (autoantibodies against GAD65 and proinsulin; pancreatic islet infiltration by CD4+, CD8+ B220+, CD11b+ and CD11c+ immune cells). Disease was markedly accelerated and had deeper penetrance after adjuvanted antigen priming with proinsulin (mean onset 11 weeks and incidence 100% by 20 weeks post challenge). Moreover, the diabetogenic effect of proinsulin located to the 15-residue B29-C11 region.Conclusions/interpretationOur study identifies a proinsulin-derived peptide region that is highly diabetogenic on the HLA-DR3-DQ2 background using an in vivo model. This approach and the peptide region identified may have wider implications for future studies of human type 1 diabetes.

Sex as a determinant of type 1 diabetes at diagnosis

OBJECTIVE The present study tested the hypothesis that girls have a more aggressive disease process than boys at the diagnosis of type 1 diabetes (T1D). METHODS Demographic and clinical characteristics, the humoral autoantibody profile, and the genetic risk assessed by the presence of human leukocyte antigen DR-DQ haplotypes were analyzed in terms of sex in 4993 children and adolescents diagnosed with T1D between January 2003 and December 2016. RESULTS A clear male preponderance (56.6%) was observed in our cohort and boys were significantly older than girls at clinical diagnosis (mean 8.3 vs 7.7 years, P < .001). Age-adjusted analyses showed a poorer metabolic decompensation in girls than boys at diagnosis. Boys tested more often positive for autoantibodies against insulin autoantibodies (P = .008), islet antigen-2 autoantibodies (P = .033), and zinc transporter 8 autoantibodies (P = .027), whereas girls had a higher frequency of glutamic acid decarboxylase autoantibodies (GADA) (P < .001) and higher GADA (P < .001) and islet cell antibody titers (P = .001). We did not find any significant differences in the genetic risk profile between girls and boys. CONCLUSIONS Our data show that the metabolic derangement is more severe in girls already at diagnosis of T1D and this finding is independent of age. The immunologic aggressiveness of the disease is more variable as the predominance of different autoantibodies varies between sexes with a higher frequency of GADA in girls, while the 3 other biochemical autoantibodies were more common in boys.

Development and validation of multivariable clinical diagnostic models to identify type 1 diabetes requiring rapid insulin therapy in adults aged 18–50 years

ObjectiveTo develop and validate multivariable clinical diagnostic models to assist distinguishing between type 1 and type 2 diabetes in adults aged 18–50.DesignMultivariable logistic regression analysis was used to develop classification...

Clinical manifestation and islet β-cell function of a subtype of latent autoimmune diabetes in adults (LADA): positive for T cell responses in phenotypic type 2 diabetes.

To investigate the possibility of identifying a subtype of latent autoimmune diabetes in adults (LADA), T-LADA (T cell responses-positive and autoantibody-negative) from patients with phenotypic type 2 diabetes (T2D) by enzyme-linked immunospot (ELISPOT). Eighty-two patients with phenotypic T2D were studied. Autoantibodies against glutamic acid decarboxylase (GAD), insulinoma-associated protein-2 and zinc transporter 8 were measured by radioligand assay. Thirty-nine Ab+ and 43 Ab- patients with phenotypic T2D were enrolled for T cell assay of responses to GAD65 and C-peptide antigen by ELISPOT. (1) Eleven of 43 Ab- participants with phenotypic T2D were demonstrated interferon (IFN)-γ secreting T cells by ELISPOT, while 13 of 39 Ab+ patients with phenotypic T2D were positive for T cells responses to islet antigens. (2) The onset ages of T cell+ people with phenotypic T2D were younger than that of T cell- individuals (42.7 ± 9.3 vs. 48.2 ± 10.2years, P = 0.025). Moreover, T cell+ patients with T2D displayed a significantly lower fasting C-peptide (FCP) compared with T cell- participants [0.28 (0.02-0.84) vs. 0.42 (0.05-1.26) nmol/L, P = 0.013]. (3) Ab-T+ group had a significantly lower FCP compared with Ab-T- group [0.31 (0.13-0.84) vs. 0.51 (0.07-1.26) nmol/L, P = 0.023]. By measuring T cell responses to islet antigens in patients with phenotypic T2D, we identified a specific subtype of LADA who may be associated with worse basal β-cell function than classic T2D (Ab-T-).

Type 1 diabetes genetic risk score discriminates between monogenic and Type 1 diabetes in children diagnosed at the age of

AimTo examine the extent to which discriminatory testing using antibodies and Type 1 diabetes genetic risk score, validated in European populations, is applicable in a non‐European population.MethodsWe recruited 127 unrelated children with diabetes diagnosed between 9 months and 5 years from two centres in Iran. All children underwent targeted next‐generation sequencing of 35 monogenic diabetes genes. We measured three islet autoantibodies (islet antigen 2, glutamic acid decarboxylase and zinc transporter 8) and generated a Type 1 diabetes genetic risk score in all children.ResultsWe identified six children with monogenic diabetes, including four novel mutations: homozygous mutations in WFS1 (n=3), SLC19A2 and SLC29A3, and a heterozygous mutation in GCK. All clinical features were similar in children with monogenic diabetes (n=6) and in the rest of the cohort (n=121). The Type 1 diabetes genetic risk score discriminated children with monogenic from Type 1 diabetes [area under the receiver‐operating characteristic curve 0.90 (95% CI 0.83–0.97)]. All children with monogenic diabetes were autoantibody‐negative. In children with no mutation, 59 were positive to glutamic acid decarboxylase, 39 to islet antigen 2 and 31 to zinc transporter 8. Measuring zinc transporter 8 increased the number of autoantibody‐positive individuals by eight.ConclusionsThe present study provides the first evidence that Type 1 diabetes genetic risk score can be used to distinguish monogenic from Type 1 diabetes in an Iranian population with a large number of consanguineous unions. This test can be used to identify children with a higher probability of having monogenic diabetes who could then undergo genetic testing. Identification of these individuals would reduce the cost of treatment and improve the management of their clinical course.

Characteristics of Slow Progression to Type 1 Diabetes in Children With Increased HLA-Conferred Disease Risk

Characterization of slow progression to type 1 diabetes (T1D) may reveal novel means for prevention of T1D. Slow progressors might carry natural immunomodulators that delay β-cell destruction and mediate preservation of β-cell function. To identify demographic, genetic, and immunological characteristics of slow progression from seroconversion to clinical T1D. HLA-susceptible children (n = 7410) were observed from birth for islet cell antibody (ICA), insulin autoantibody (IAA), glutamic acid decarboxylase (GADA), and islet antigen-2 autoantibodies (IA-2A), and for clinical T1D. Disease progression that lasted ≥7.26 years (slowest) quartile from initial seroconversion to diagnosis was considered slow. Autoantibody and genetic characteristics including 45 non-HLA single nucleotide polymorphisms (SNPs) predisposing to T1D were analyzed. By the end of 2015, 1528 children (21%) had tested autoantibody positive and 247 (16%) had progressed to T1D. The median delay from seroconversion to diagnosis was 8.7 years in slow (n = 62, 25%) and 3.0 years in other progressors. Compared with other progressors, slow progressors were less often multipositive, had lower ICA and IAA titers, and lower frequency of IA-2A at seroconversion. Slow progressors were born more frequently in the fall, whereas other progressors were born more often in the spring. Compared with multipositive nonprogressors, slow progressors were younger, had higher ICA titers, and higher frequency of IAA and multiple autoantibodies at seroconversion. We found no differences in the distributions of non-HLA SNPs between progressors. We observed differences in autoantibody characteristics and the season of birth among progressors, but no characteristics present at seroconversion that were specifically predictive for slow progression.

Landmark models to define the age-adjusted risk of developing stage 1 type 1 diabetes across childhood and adolescence

BackgroundAutoimmune diseases are often preceded by an asymptomatic autoantibody-positive phase. In type 1 diabetes, the detection of autoantibodies to pancreatic islet antigens in genetically at-risk children is prognostic for future clinical diabetes. Testing for islet autoantibodies is, therefore, performed in a range of clinical studies. Accurate risk estimates that consider the a priori genetic risk and other risk modifiers are an important component of screening. The age of an individual is an under-appreciated risk modifier. The aim of this study was to provide age-adjusted risk estimates for the development of autoantibodies across childhood in genetically at-risk children.MethodsThe prospective BABYDIAB and BABYDIET studies included 2441 children from birth who had a first-degree relative with type 1 diabetes. Children were born between 1989 and 2006 and were regularly followed from birth for the development of islet autoantibodies and diabetes. A landmark analysis was performed to estimate the risk of islet autoantibodies at birth and at the age 3.5, 6.5 and 12.5 years. Exponential decay curves were fitted for the risk by the age of 20 years.ResultsThe risk of islet autoantibodies by the age of 20 years was 8%, 4.6%, 2.6% and 0.9%, at the landmark ages of birth, 3.5, 6.5 and 12.5 years, respectively. The short-term risks (within 6 years of follow-up) at these landmark ages were 5.3%, 2.9%, 1.8% and 1%, respectively. The decline in autoantibody risk with age was modelled using a one-phase exponential decay curve (r = 0.99) with a risk half-life of 3.7 years. This risk decay model was remarkably consistent when the outcome was defined as islet autoantibody-positive or multiple islet autoantibody-positive and when the study cohort was stratified by HLA risk genotype. A similar decay model was observed for coeliac disease-associated transglutaminase antibodies in the same cohort. Unlike the risk of developing islet autoantibodies, the rate of developing clinical diabetes in children who were islet autoantibody-positive did not decline with age.ConclusionThe risk of developing autoantibodies drops exponentially with age in children with a first-degree relative with type 1 diabetes.

Investigating optimal β-cell-preserving treatment in latent autoimmune diabetes in adults: Results from a 21-month randomized trial.

To compare outcomes of glucagon-stimulated C-peptide tests (GSCTs) in people with latent autoimmune diabetes in adults (LADA) after a 21-month intervention with either insulin or the dipeptidyl peptidase-4 inhibitor sitagliptin. We included 64 glutamic acid decarboxylase (GAD) antibody-positive individuals, who were diagnosed with diabetes <3 years before the study, aged 30 to 70 years, and without clinical need for insulin treatment. We stratified participants by age and body mass index (BMI) and evaluated β-cell function by GSCT after a 48-hour temporary withdrawal of study medication. Age at randomization (mean 53 years), BMI (mean 27 kg/m2 ) and metabolic markers were similar between treatment arms. Glycated haemoglobin concentrations during intervention did not differ between arms. Fasting C-peptide concentrations after the intervention were similar, as were stimulated C-peptide levels (0.82 ± 0.63 nmol/L after insulin, 0.82 ± 0.46 nmol/L after sitagliptin; nonsignificant). Autoimmunity in the study population (estimated from GAD antibody titres and positivity/no positivity for zinc transporter 8 and islet antigen 2 antibodies) affected the evolution of the GSCT results significantly, which deteriorated in participants with high but not in those with low autoimmunity. Adjustment using analysis of covariance for the degree of autoimmunity did not alter the findings of no difference between treatment arms. β-cell function after intervention was similar in patients with insulin- and sitagliptin-treated LADA, regardless of the strength of autoimmunity. Further, participants with low levels of GAD antibodies did not experience progressive deterioration of β-cell function over a 21-month period. Taken together, these findings could be useful for clinicians' choices of treatment in people with LADA.