Zinc transporter 8 autoantibodies and their association with SLC30A8 and HLA-DQ genes differ between immigrant and Swedish patients with newly diagnosed type 1 diabetes in the Better Diabetes Diagnosis study

Childhood screening for type 1 diabetes comparing automated multiplex Antibody Detection by Agglutination-PCR (ADAP) with single plex islet autoantibody radiobinding assays

BACKGROUND

Two or more autoantibodies against either insulin (IAA), glutamic acid decarboxylase (GADA), islet antigen-2 (IA-2A) or zinc transporter 8 (ZnT8A) denote stage 1 (normoglycemia) or stage 2 (dysglycemia) type 1 diabetes prior to stage 3 type 1 diabetes. Automated multiplex Antibody Detection by Agglutination-PCR (ADAP) assays in two laboratories were compared to single plex radiobinding assays (RBA) to define threshold levels for diagnostic specificity and sensitivity.

METHODS

IAA, GADA, IA-2A and ZnT8A were analysed in 1504 (54% females) population based controls (PBC), 456 (55% females) doctor's office controls (DOC) and 535 (41% females) blood donor controls (BDC) as well as in 2300 (48% females) patients newly diagnosed (1-10 years of age) with stage 3 type 1 diabetes. The thresholds for autoantibody positivity were computed in 100 10-fold cross-validations to separate patients from controls either by maximizing the χ2-statistics (chisq) or using the 98th percentile of specificity (Spec98). Mean and 95% CI for threshold, sensitivity and specificity are presented.

FINDINGS

The ADAP ROC curves of the four autoantibodies showed comparable AUC in the two ADAP laboratories and were higher than RBA. Detection of two or more autoantibodies using chisq showed 0.97 (0.95, 0.99) sensitivity and 0.94 (0.91, 0.97) specificity in ADAP compared to 0.90 (0.88, 0.95) sensitivity and 0.97 (0.94, 0.98) specificity in RBA. Using Spec98, ADAP showed 0.92 (0.89, 0.95) sensitivity and 0.99 (0.98, 1.00) specificity compared to 0.89 (0.77, 0.86) sensitivity and 1.00 (0.99, 1.00) specificity in the RBA. The diagnostic sensitivity and specificity were higher in PBC compared to DOC and BDC.

INTERPRETATION

ADAP was comparable in two laboratories, both comparable to or better than RBA, to define threshold levels for two or more autoantibodies to stage type 1 diabetes.

FUNDING

Supported by The Leona M. and Harry B. Helmsley Charitable Trust (grant number 2009-04078), the Swedish Foundation for Strategic Research (Dnr IRC15-0067) and the Swedish Research Council, Strategic Research Area (Dnr 2009-1039). AL was supported by the DiaUnion collaborative study, co-financed by EU Interreg ÖKS, Capital Region of Denmark, Region Skåne and the Novo Nordisk Foundation.

Development of a clinical calculator to aid the identification of MODY in pediatric patients at the time of diabetes diagnosis

Maturity Onset Diabetes of the Young (MODY) is a young-onset, monogenic form of diabetes without needing insulin treatment. Diagnostic testing is expensive. To aid decisions on who to test, we aimed to develop a MODY probability calculator for paediatric cases at the time of diabetes diagnosis, when the existing "MODY calculator" cannot be used. Firth logistic regression models were developed on data from 3541 paediatric patients from the Swedish 'Better Diabetes Diagnosis' (BDD) population study (n = 46 (1.3%) MODY (HNF1A, HNF4A, GCK)). Model performance was compared to using islet autoantibody testing. HbA1c, parent with diabetes, and absence of polyuria were significant independent predictors of MODY. The model showed excellent discrimination (c-statistic = 0.963) and calibrated well (Brier score = 0.01). MODY probability > 1.3% (ie. above background prevalence) had similar performance to being negative for all 3 antibodies (positive predictive value (PPV) = 10% v 11% respectively i.e. ~ 1 in 10 positive test rate). Probability > 1.3% and negative for 3 islet autoantibodies narrowed down to 4% of the cohort, and detected 96% of MODY cases (PPV = 31%). This MODY calculator for paediatric patients at time of diabetes diagnosis will help target genetic testing to those most likely to benefit, to get the right diagnosis.

Islet Autoantibodies to Pancreatic Insulin-Producing Beta Cells in Adolescent and Adults with Type 1 Diabetes Mellitus: A Cross-Sectional Study

(1) Background: Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease caused by the destruction of pancreatic insulin-producing beta cells. T1D is one of the most common endocrine and metabolic disorders occurring in children. Autoantibodies against pancreatic insulin-producing beta cells are important immunological and serological markers of T1D. Zinc transporter 8 autoantibody (ZnT8) is a recently identified autoantibody in T1D; however, no data on ZnT8 autoantibody in the Saudi Arabian population have been reported. Thus, we aimed to investigate the prevalence of islet autoantibodies (IA-2 and ZnT8) in adolescents and adults with T1D according to age and disease duration. (2) Methods: In total, 270 patients were enrolled in this cross-sectional study. After meeting the study's inclusion and exclusion criteria, 108 patients with T1D (50 men and 58 women) were assessed for T1D autoantibody levels. Serum ZnT8 and IA-2 autoantibodies were measured using commercial enzyme-linked immunosorbent assay kits. (3) Results: IA-2 and ZnT8 autoantibodies were present in 67.6% and 54.6% of patients with T1D, respectively. Autoantibody positivity was found in 79.6% of the patients with T1D. Both the IA-2 and ZnT8 autoantibodies were frequently observed in adolescents. The prevalence of IA-2 and ZnT8 autoantibodies in patients with a disease duration < 1 year was 100% and 62.5%, respectively, which declined with an increase in disease duration (p < 0.020). Logistic regression analysis revealed a significant relationship between age and autoantibodies (p < 0.004). (4) Conclusions: The prevalence of IA-2 and ZnT8 autoantibodies in the Saudi Arabian T1D population appears to be higher in adolescents. The current study also showed that the prevalence of autoantibodies decreased with disease duration and age. IA-2 and ZnT8 autoantibodies are important immunological and serological markers for T1D diagnosis in the Saudi Arabian population.

Evaluation of the RSR 3 screen ICA™ and 2 screen ICA™ as screening assays for type 1 diabetes in Sweden

AIM

The study aim was to evaluate the RSR 3 Screen ICA™ and 2 Screen ICA™ for detection of islet cell autoimmunity in healthy Swedish subjects and patients with newly diagnosed type 1 diabetes (T1D).

METHODS

3 Screen is designed for combined detection of autoantibodies to glutamic acid decarboxylase (GADA), to the islet antigen IA-2 (IA-2A) and to zinc transporter 8 (ZnT8A), while 2 Screen detects GADA and IA-2A. Serum samples from 100 T1D patients at onset and 200 healthy controls were studied.

RESULTS

3 Screen achieved 93% assay sensitivity and 97.5% specificity, while 2 Screen achieved 91% assay sensitivity and 98.5% specificity. Samples were also tested in assays for individual autoantibodies. There was only one 3 Screen positive healthy control sample (0.5%) that was positive for multiple autoantibodies (IA-2A and ZnT8A). In contrast, most of the 93 3 Screen positive patients were positive for multiple autoantibodies with 72% (67/93) positive for both GADA and IA-2A and 57% (53/93) positive for three autoantibodies (GADA, IA-2A and ZnT8A). Insulin autoantibodies (IAA, measured by radioimmunoassay) were positive in 13 patients and two healthy controls.

CONCLUSION

3 Screen achieved high sensitivity and specificity, suitable for islet cell autoimmunity screening in a healthy population. In the case of 3 Screen positivity, further assays for GADA, IA-2A and ZnT8A are required to check for multiple autoantibody positivity, a hallmark for progression to T1D. In addition, testing for IAA in children below two years of age is warranted.

Long-Term GAD-alum Treatment Effect on Different T-Cell Subpopulations in Healthy Children Positive for Multiple Beta Cell Autoantibodies

Objective

The objective of this study was to explore whether recombinant GAD65 conjugated hydroxide (GAD-alum) treatment affected peripheral blood T-cell subpopulations in healthy children with multiple beta cell autoantibodies.

Method

The Diabetes Prevention–Immune Tolerance 2 (DiAPREV-IT 2) clinical trial enrolled 26 children between 4 and 13 years of age, positive for glutamic acid decarboxylase autoantibody (GADA) and at least one other autoantibody (insulin, insulinoma antigen-2, or zinc transporter 8 autoantibody (IAA, IA-2A, or ZnT8A)) at baseline. The children were randomized to two doses of subcutaneously administered GAD-alum treatment or placebo, 30 days apart. Complete blood count (CBC) and immunophenotyping of T-cell subpopulations by flow cytometry were performed regularly during the 24 months of follow-up posttreatment. Cross-sectional analyses were performed comparing lymphocyte and T-cell subpopulations between GAD-alum and placebo-treated subjects.

Results

GAD-alum-treated children had lower levels of lymphocytes (10⁹ cells/L) (p = 0.006), T-cells (10³ cells/μL) (p = 0.008), T-helper cells (10³ cells/μL) (p = 0.014), and cytotoxic T-cells (10³ cells/μL) (p = 0.023) compared to the placebo-treated children 18 months from first GAD-alum injection. This difference remained 24 months after the first treatment for lymphocytes (p = 0.027), T-cells (p = 0.022), T-helper cells (p = 0.048), and cytotoxic T-cells (p = 0.018).

Conclusion

Our findings suggest that levels of total T-cells and T-cell subpopulations declined 18 and 24 months after GAD-alum treatment in healthy children with multiple beta-cell autoantibodies including GADA.

The common rs13266634 C > T variant in SLC30A8 contributes to the heterogeneity of phenotype and clinical features of both type 1 and type 2 diabetic subtypes

AIMS

T2D and T1D are phenotypically heterogeneous. This study aims to reveal the relationship between the common SLC30A8 rs13266634 variant and subgroups of T2D and T1D and their clinical characteristics.

METHODS

We included 3158 OGTT-based healthy controls, unrelated 1754 T2D, and 1675 autoantibody-positive T1D individuals. The associations between rs13266634 and subtypes of T2D, T1D, autoantibody status and glycemic-related quantitative traits were performed by binary logistic regression analysis under the additive model and multiple linear regression with appropriate adjustment.

RESULTS

We found that the T allele of rs13266634 was protectively associated with lean (OR = 0.810, P = 6.91E-04) but not obese T2D with considerable heterogeneity (P = 0.018). This allele also conferred significant protection with T1D of single (OR = 0.847, P = 9.76E-03), but not multi autoantibodies with substantial heterogeneity (P = 0.005). This variant significantly affected OGTT-related insulin release in lean (P = 2.66E-03, 3.88E-03 for CIR and DI, respectively) but not obese healthy individuals. Furthermore, rs13266634 T allele correlated with the risk of ZnT8A (OR = 1.440, P = 3.31E-05) and IA-2A (OR = 1.219, P = 1.32E-03) positivity, with more effect size in children/adolescents compared with adult-onset T1D subtypes.

CONCLUSIONS

These suggested that the SLC30A8 rs13266634 variant might be put into genetic risk scores to assess the risk of the subtypes of T1D and T2D and their related clinical features.

Heterogeneity of beta-cell function in subjects with multiple islet autoantibodies in the TEDDY family prevention study - TEFA

BACKGROUND

Individuals with multiple islet autoantibodies are at increased risk for clinical type 1 diabetes and may proceed gradually from stage to stage complicating the recruitment to secondary prevention studies. We evaluated multiple islet autoantibody positive subjects before randomisation for a clinical trial 1 month apart for beta-cell function, glucose metabolism and continuous glucose monitoring (CGM). We hypothesized that the number and type of islet autoantibodies in combination with different measures of glucose metabolism including fasting glucose, HbA1c, oral glucose tolerance test (OGTT), intra venous glucose tolerance test (IvGTT) and CGM allows for more precise staging of autoimmune type 1 diabetes than the number of islet autoantibodies alone.

METHODS

Subjects (n = 57) at 2-50 years of age, positive for two or more islet autoantibodies were assessed by fasting plasma insulin, glucose, HbA1c as well as First Phase Insulin Response (FPIR) in IvGTT, followed 1 month later by OGTT, and 1 week of CGM (n = 24).

RESULTS

Autoantibodies against GAD65 (GADA; n = 52), ZnT8 (ZnT8A; n = 40), IA-2 (IA-2A; n = 38) and insulin (IAA; n = 28) were present in 9 different combinations of 2-4 autoantibodies. Fasting glucose and HbA1c did not differ between the two visits. The estimate of the linear relationship between log2-transformed FPIR as the outcome and log2-transformed area under the OGTT glucose curve (AUC) as the predictor, adjusting for age and sex was - 1.88 (- 2.71, - 1.05) p = 3.49 × 10-5. The direction of the estimates for all glucose metabolism measures was positive except for FPIR, which was negative. FPIR was associated with higher blood glucose. Both the median and the spread of the CGM glucose data were significantly associated with higher glucose values based on OGTT, higher HbA1c, and lower FPIR. There was no association between glucose metabolism, autoantibody number and type except that there was an indication that the presence of at least one of ZnT8(Q/R/W) A was associated with a lower log2-transformed FPIR (- 0.80 (- 1.58, - 0.02), p = 0.046).

CONCLUSIONS

The sole use of two or more islet autoantibodies as inclusion criterion for Stage 1 diabetes in prevention trials is unsatisfactory. Staging type 1 diabetes needs to take the heterogeneity in beta-cell function and glucose metabolism into account.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02605148 , November 16, 2015.

Autoantibodies to Zinc Transporter 8 and SLC30A8 Genotype in Type 1 Diabetes Childhood: A Pioneering Study in North Africa

BACKGROUND

Type 1 diabetes (T1D) occurs as a result of insulin deficiency due to destructive lesions of pancreatic β cells. In addition to classical autoantibodies (Abs) to islet cell antigens, antizinc transporter 8 Abs (ZnT8-Ab) have been recently described in T1D.

OBJECTIVE

As no data on ZnT8-Ab in Tunisian patients has been reported, we aim to evaluate the relationships between ZnT8-Ab, ZnT8 coding gene (SLC30A8) promoter polymorphism, and T1D risk in newly diagnosed children.

METHODS

ZnT8-Ab were measured in the serum of T1D newly affected children (n = 156) who were admitted to the pediatric department of the Hedi Chaker University Hospital of Sfax. Rs13266634 was genotyped in T1D children and 79 of their first-degree parents. The SPSS software was used to analyze the serological data. Allelic association analysis was conducted with family-based association tests implemented in the FBAT program v1.5.1.

RESULTS

ZnT8-Ab was detected in 66/156 (42.3%) of T1D newly diagnosed children. Among them, 6 (9%) presented ZnT8-Ab as the only humoral marker. The inclusion of ZnT8-Ab increased the number of Ab-positive patients to 90% and reduced the negative ones by 27%. There was no evidence of any overtransmission of any allele of the rs13266634 C/T polymorphism from parents to affected T1D children, nor of any correlation with any clinical or serological parameter. After the T1D disease onset age adjustment, a significant association was observed with the C allele suggesting that it could have a susceptibility role.

CONCLUSION

ZnT8-Ab appears as a relevant diagnostic marker for T1D in Tunisian children, especially at the onset of the disease as teenagers.

Neutralizing Ljungan virus antibodies in children with newly diagnosed type 1 diabetes

Ljungan virus (LV), a Parechovirus of the Picornavirus family, first isolated from a bank vole at the Ljungan river in Sweden, has been implicated in the risk for autoimmune type 1 diabetes. An assay for neutralizing Ljungan virus antibodies (NLVA) was developed using the original 87-012 LV isolate. The goal was to determine NLVA titres in incident 0-18 years old newly diagnosed type 1 diabetes patients (n=67) and school children controls (n=292) from Jämtland county in Sweden. NLVA were found in 41 of 67 (61 %) patients compared to 127 of 292 (44 %) controls (P=0.009). In the type 1 diabetes patients, NLVA titres were associated with autoantibodies to glutamic acid decarboxylase (GADA) (P=0.023), but not to autoantibodies against insulin (IAA) or islet antigen-2 (IA-2A). The NLVA assay should prove useful for further investigations to determine levels of LV antibodies in patients and future studies to determine a possible role of LV in autoimmune type 1 diabetes.

The KAG motif of HLA-DRB1 (β71, β74, β86) predicts seroconversion and development of type 1 diabetes

BACKGROUND

HLA-DR4, a common antigen of HLA-DRB1, has multiple subtypes that are strongly associated with risk of type 1 diabetes (T1D); however, some are risk neutral or resistant. The pathobiological mechanism of HLA-DR4 subtypes remains to be elucidated.

METHODS

We used a population-based case-control study of T1D (962 patients and 636 controls) to decipher genetic associations of HLA-DR4 subtypes and specific residues with susceptibility to T1D. Using a birth cohort of 7865 children with periodically measured islet autoantibodies (GADA, IAA or IA-2A), we proposed to validate discovered genetic associations with a totally different study design and time-to-seroconversions prior to clinical onset of T1D. A novel analytic strategy hierarchically organized the HLA-DRB1 alleles by sequence similarity and identified critical amino acid residues by minimizing local genomic architecture and higher-order interactions.

FINDINGS

Three amino acid residues of HLA-DRB1 (β71, β74, β86) were found to be predictive of T1D risk in the population-based study. The "KAG" motif, corresponding to HLA-DRB1×04:01, was most strongly associated with T1D risk ([O]dds [R]atio=3.64, p = 3.19 × 10-64). Three less frequent motifs ("EAV", OR = 2.55, p = 0.025; "RAG", OR = 1.93, p = 0.043; and "RAV", OR = 1.56, p = 0.003) were associated with T1D risk, while two motifs ("REG" and "REV") were equally protective (OR = 0.11, p = 4.23 × 10-4). In an independent birth cohort of HLA-DR3 and HLA-DR4 subjects, those having the "KAG" motif had increased risk for time-to-seroconversion (Hazard Ratio = 1.74, p = 6.51 × 10-14) after adjusting potential confounders.

INTERPRETATIONS

DNA sequence variation in HLA-DRB1 at positions β71, β74, and β86 are non-conservative (β74 A→E, β71 E vs K vs R and β86 G vs V). They result in substantial differences in peptide antigen anchor pocket preferences at p1, p4 and potentially neighboring regions such as pocket p7. Differential peptide antigen binding is likely to be affected. These sequence substitutions may account for most of the HLA-DR4 contribution to T1D risk as illustrated in two HLA-peptide model complexes of the T1D autoantigens preproinsulin and GAD65.

FUNDING

National Institute of Diabetes and Digestive and Kidney Diseases and the Swedish Child Diabetes Foundation and the Swedish Research Council.

Nine residues in HLA-DQ molecules determine with susceptibility and resistance to type 1 diabetes among young children in Sweden

HLA-DQ molecules account over 50% genetic risk of type 1 diabetes (T1D), but little is known about associated residues. Through next generation targeted sequencing technology and deep learning of DQ residue sequences, the aim was to uncover critical residues and their motifs associated with T1D. Our analysis uncovered (αa1, α44, α157, α196) and (β9, β30, β57, β70, β135) on the HLA-DQ molecule. Their motifs captured all known susceptibility and resistant T1D associations. Three motifs, “DCAA-YSARD” (OR = 2.10, p = 1.96*10⁻²⁰), “DQAA-YYARD” (OR = 3.34, 2.69*10⁻⁷²) and “DQDA-YYARD” (OR = 3.71, 1.53*10⁻⁶) corresponding to DQ2.5 and DQ8.1 (the latter two motifs) associated with susceptibility. Ten motifs were significantly associated with resistance to T1D. Collectively, homozygous DQ risk motifs accounted for 43% of DQ-T1D risk, while homozygous DQ resistant motifs accounted for 25% protection to DQ-T1D risk. Of the identified nine residues five were within or near anchoring pockets of the antigenic peptide (α44, β9, β30, β57 and β70), one was the N-terminal of the alpha chain (αa1), one in the CD4-binding region (β135), one in the putative cognate TCR-induced αβ homodimerization process (α157), and one in the intra-membrane domain of the alpha chain (α196). Finding these critical residues should allow investigations of fundamental properties of host immunity that underlie tolerance to self and organ-specific autoimmunity.

Beta cell function in participants with single or multiple islet autoantibodies at baseline in the TEDDY Family Prevention Study: TEFA

Aim

The aim of the present study was to assess beta cell function based on an oral glucose tolerance test (OGTT) in participants with single islet autoantibody or an intravenous glucose tolerance test (IvGTT) in participants with multiple islet autoantibodies.

Materials and methods

Healthy participants in Sweden and Finland, between 2 and 49.99 years of age previously identified as positive for a single (n = 30) autoantibody to either insulin, glutamic acid decarboxylase, islet antigen-2, zinc transporter 8 or islet cell antibodies or multiple autoantibodies (n = 46), were included. Participants positive for a single autoantibody underwent a 6-point OGTT while participants positive for multiple autoantibodies underwent an IvGTT. Glucose, insulin and C-peptide were measured from OGTT and IvGTT samples.

Results

All participants positive for a single autoantibody had a normal glucose tolerance test with 120 minutes glucose below 7.70 mmol/L and HbA1c values within the normal range (<42 mmol/mol). Insulin responses to the glucose challenge on OGTT ranged between 13.0 and 143 mIU/L after 120 minutes with C-peptide values between 0.74 and 4.60 nmol/L. In Swedish participants, the first-phase insulin response (FPIR) on IvGTT was lower in those positive for three or more autoantibodies (n = 13; median 83.0 mIU/L; range 20.0-343) compared to those with two autoantibodies (n = 15; median 146 mIU/L; range 19.0-545; P = .0330).

Conclusion

Participants positive for a single autoantibody appeared to have a normal beta cell function. Participants positive for three or more autoantibodies had a lower FPIR as compared to participants with two autoantibodies, supporting the view that their beta cell function had deteriorated.

Dynamics of Islet Autoantibodies During Prospective Follow-Up From Birth to Age 15 Years

CONTEXT

We set out to characterize the dynamics of islet autoantibodies over the first 15 years of life in children carrying genetic susceptibility to type 1 diabetes (T1D). We also assessed systematically the role of zinc transporter 8 autoantibodies (ZnT8A) in this context.

DESIGN

HLA-predisposed children (N = 1006, 53.0% boys) recruited from the general population during 1994 to 1997 were observed from birth over a median time of 14.9 years (range, 1.9-15.5 years) for ZnT8A, islet cell (ICA), insulin (IAA), glutamate decarboxylase (GADA), and islet antigen-2 (IA-2A) antibodies, and for T1D.

RESULTS

By age 15.5 years, 35 (3.5%) children had progressed to T1D. Islet autoimmunity developed in 275 (27.3%) children at a median age of 7.4 years (range, 0.3-15.1 years). The ICA seroconversion rate increased toward puberty, but the biochemically defined autoantibodies peaked at a young age. Before age 2 years, ZnT8A and IAA appeared commonly as the first autoantibody, but in the preschool years IA-2A- and especially GADA-initiated autoimmunity increased. Thereafter, GADA-positive seroconversions continued to appear steadily until ages 10 to 15 years. Inverse IAA seroconversions occurred frequently (49.3% turned negative) and marked a prolonged delay from seroconversion to diagnosis compared to persistent IAA (8.2 vs 3.4 years; P = .01).

CONCLUSIONS

In HLA-predisposed children, the primary autoantibody is characteristic of age and might reflect the events driving the disease process toward clinical T1D. Autoantibody persistence affects the risk of T1D. These findings provide a framework for identifying disease subpopulations and for personalizing the efforts to predict and prevent T1D.

Next-Generation HLA Sequence Analysis Uncovers Seven HLA-DQ Amino Acid Residues and Six Motifs Resistant to Childhood Type 1 Diabetes

HLA-DQA1 and -DQB1 genes have significant and potentially causal associations with autoimmune type 1 diabetes (T1D). To follow up on the earlier analysis on high-risk HLA-DQ2.5 and DQ8.1, the current analysis uncovers seven residues (αa1, α157, α196, β9, β30, β57, and β70) that are resistant to T1D among subjects with DQ4-, 5-, 6-, and 7-resistant DQ haplotypes. These 7 residues form 13 common motifs: 6 motifs are significantly resistant, 6 motifs have modest or no associations (P values >0.05), and 1 motif has 7 copies observed among control subjects only. The motifs "DAAFYDG," "DAAYHDG," and "DAAYYDR" have significant resistance to T1D (odds ratios [ORs] 0.03, 0.25, and 0.18; P = 6.11 × 10^-24, 3.54 × 10^-15, and 1.03 × 10^-21, respectively). Remarkably, a change of a single residue from the motif "DAAYHDG" to "DAAYHSG" (D to S at β57) alters the resistance potential, from resistant motif (OR 0.15; P = 3.54 × 10^-15) to a neutral motif (P = 0.183), the change of which was significant (Fisher P value = 0.0065). The extended set of linked residues associated with T1D resistance and unique to each cluster of HLA-DQ haplotypes represents facets of all known features and functions of these molecules: antigenic peptide binding, peptide-MHC class II complex stability, β167-169 RGD loop, T-cell receptor binding, formation of homodimer of α-β heterodimers, and cholesterol binding in the cell membrane rafts. Identification of these residues is a novel understanding of resistant DQ associations with T1D. Our analyses endow potential molecular approaches to identify immunological mechanisms that control disease susceptibility or resistance to provide novel targets for immunotherapeutic strategies.

Zinc transporter 8 autoantibody in the diagnosis of type 1 diabetes in children

BACKGROUND

Type 1 diabetes (T1D) is an organ-specific autoimmune disease related to the autoimmune response against pancreatic β-cells. Zinc transporter 8 (ZnT8), an islet-specific gene product localized to the β-cell insulin granule, was recently identified as an autoantigen in T1D.

PURPOSE

To evaluate the use of ZnT8 autoantibody (ZnT8A) for diagnosing T1D.

METHODS

This case-control study was conducted at Dr. Soetomo General Hospital, Surabaya, Indonesia, from March to May 2019. Children younger than 18 years of age with T1D based on the International Society for Pediatric and Adolescent Diabetes guideline and healthy controls were included. We measured ZnT8A level using enzyme-linked immunosorbent assay (cutoff value, 0.315).

RESULTS

There were 30 children with T1D (50.0% boys; mean age, 11.3±3.7 years) and 18 healthy controls (44.4% boys; mean age, 8.3±3.1 years); 1 patient in each group was Madurese, while the others were Javanese. Twenty-two of 30 subjects with T1D (73.3%) tested positive for ZnT8A compared to 5 of 18 controls (27.8%) (P=0.02; odds ratio, 7.15; 95% confidence interval, 1.93-26.52). When ZnT8A-positive and -negative T1D cases were compared, no differences were detected in age at diagnosis, duration of diabetes, presence of ketoacidosis, body mass index, glycosylated hemoglobin concentration, or C-peptide concentrations.

CONCLUSION

ZnT8A may be useful in the diagnosis of T1D.

Motifs of Three HLA-DQ Amino Acid Residues (α44, β57, β135) Capture Full Association With the Risk of Type 1 Diabetes in DQ2 and DQ8 Children

HLA-DQA1 and -DQB1 are strongly associated with type 1 diabetes (T1D), and DQ8.1 and DQ2.5 are major risk haplotypes. Next-generation targeted sequencing of HLA-DQA1 and -DQB1 in Swedish newly diagnosed 1- to 18 year-old patients (n = 962) and control subjects (n = 636) was used to construct abbreviated DQ haplotypes, converted into amino acid (AA) residues, and assessed for their associations with T1D. A hierarchically organized haplotype (HOH) association analysis allowed 45 unique DQ haplotypes to be categorized into seven clusters. The DQ8/9 cluster included two DQ8.1 risk and the DQ9 resistant haplotypes, and the DQ2 cluster included the DQ2.5 risk and DQ2.2 resistant haplotypes. Within each cluster, HOH found residues α44Q (odds ratio [OR] 3.29, P = 2.38 * 10^-85) and β57A (OR 3.44, P = 3.80 * 10^-84) to be associated with T1D in the DQ8/9 cluster representing all ten residues (α22, α23, α44, α49, α51, α53, α54, α73, α184, β57) due to complete linkage disequilibrium (LD) of α44 with eight such residues. Within the DQ2 cluster and due to LD, HOH analysis found α44C and β135D to share the risk for T1D (OR 2.10, P = 1.96 * 10^-20). The motif "QAD" of α44, β57, and β135 captured the T1D risk association of DQ8.1 (OR 3.44, P = 3.80 * 10^-84), and the corresponding motif "CAD" captured the risk association of DQ2.5 (OR 2.10, P = 1.96 * 10^-20). Two risk associations were related to GAD65 autoantibody (GADA) and IA-2 autoantibody (IA-2A) but in opposite directions. CAD was positively associated with GADA (OR 1.56, P = 6.35 * 10^-8) but negatively with IA-2A (OR 0.59, P = 6.55 * 10^-11). QAD was negatively associated with GADA (OR 0.88; P = 3.70 * 10^-3) but positively with IA-2A (OR 1.64; P = 2.40 * 10^-14), despite a single difference at α44. The residues are found in and around anchor pockets 1 and 9, as potential T-cell receptor contacts, in the areas for CD4 binding and putative homodimer formation. The identification of three HLA-DQ AAs (α44, β57, β135) conferring T1D risk should sharpen functional and translational studies.

Decreased HLA-DQ expression on peripheral blood cells in children with varying number of beta cell autoantibodies

The risk for type 1 diabetes is strongly associated with HLA-DQ and the appearance of beta cell autoantibodies against either insulin, glutamate decarboxylase (GAD65), insulinoma-associated protein-2 (IA-2), or zinc transporter 8 (ZnT8). Prolonged exposure to autoantibodies may be related to T cell exhaustion known to occur in chronic infections or autoimmune disorders. It was hypothesized that autoantibody exposure may affect HLA-DQ expression on peripheral blood cells and thereby contribute to T cell exhaustion thought to be associated with the pathogenesis of type 1 diabetes. The aim of this study was to determine whether autoantibody exposure as an expression of autoimmunity burden was related to peripheral blood cell HLA-DQ cell surface expression in either 1) a cross-sectional analysis or 2) cumulative as area under the trajectory of autoantibodies during long term follow-up in the Diabetes Prediction in Skåne (DiPiS) study. Children (n = 67), aged 10–15 years were analyzed for complete blood count, HLA-DQ cell surface median fluorescence intensity (MFI), autoantibody frequency, and HLA genotypes by Next Generation Sequencing. Decreased HLA-DQ cell surface MFI with an increasing number of autoantibodies was observed in CD16⁺, CD14⁺CD16⁻, CD4⁺ and CD8⁺ cells but not in CD19⁺ cells and neutrophils. HLA-DQ cell surface MFI was associated with HLA-DQ2/8 in CD4⁺ T cells, marginally in CD14⁺CD16⁻ monocytes and CD8⁺ T cells. These associations appeared to be related to autoimmunity burden. The results suggest that HLA-DQ cell surface expression was related to HLA and autoimmunity burden.

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PBMC HLA-DQ surface expression in beta cell autoimmunity is poorly understood.

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Children, 10–15 years of age without or with beta cell autoantibodies were analyzed.

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HLA-DQ cell surface expression decreased with increasing number of autoantibodies.

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HLA-DQ cell surface expression was related to HLA and autoimmunity burden.

Absence of Islet Autoantibodies and Modestly Raised Glucose Values at Diabetes Diagnosis Should Lead to Testing for MODY: Lessons From a 5-Year Pediatric Swedish National Cohort Study

OBJECTIVE

Identifying maturity-onset diabetes of the young (MODY) in pediatric populations close to diabetes diagnosis is difficult. Misdiagnosis and unnecessary insulin treatment are common. We aimed to identify the discriminatory clinical features at diabetes diagnosis of patients with glucokinase (GCK), hepatocyte nuclear factor-1A (HNF1A), and HNF4A MODY in the pediatric population.

RESEARCH DESIGN AND METHODS

Swedish patients (n = 3,933) aged 1-18 years, diagnosed with diabetes May 2005 to December 2010, were recruited from the national consecutive prospective cohort Better Diabetes Diagnosis. Clinical data, islet autoantibodies (GAD insulinoma antigen-2, zinc transporter 8, and insulin autoantibodies), HLA type, and C-peptide were collected at diagnosis. MODY was identified by sequencing GCK, HNF1A, and HNF4A, through either routine clinical or research testing.

RESULTS

The minimal prevalence of MODY was 1.2%. Discriminatory factors for MODY at diagnosis included four islet autoantibody negativity (100% vs. 11% not-known MODY; P = 2 × 10^-44), HbA_1c (7.0% vs. 10.7% [53 vs. 93 mmol/mol]; P = 1 × 10^-20), plasma glucose (11.7 vs. 26.7 mmol/L; P = 3 × 10^-19), parental diabetes (63% vs. 12%; P = 1 × 10^-15), and diabetic ketoacidosis (0% vs. 15%; P = 0.001). Testing 303 autoantibody-negative patients identified 46 patients with MODY (detection rate 15%). Limiting testing to the 73 islet autoantibody-negative patients with HbA_1c <7.5% (58 mmol/mol) at diagnosis identified 36 out of 46 (78%) patients with MODY (detection rate 49%). On follow-up, the 46 patients with MODY had excellent glycemic control, with an HbA_1c of 6.4% (47 mmol/mol), with 42 out of 46 (91%) patients not on insulin treatment.

CONCLUSIONS

At diagnosis of pediatric diabetes, absence of all islet autoantibodies and modest hyperglycemia (HbA_1c <7.5% [58 mmol/mol]) should result in testing for GCK, HNF1A, and HNF4A MODY. Testing all 12% patients negative for four islet autoantibodies is an effective strategy for not missing MODY but will result in a lower detection rate. Identifying MODY results in excellent long-term glycemic control without insulin.

What has zinc transporter 8 autoimmunity taught us about type 1 diabetes?

Zinc transporter 8 (ZnT8), a protein highly specific to pancreatic insulin-producing beta cells, is vital for the biosynthesis and secretion of insulin. ZnT8 autoantibodies (ZnT8A) are among the most recently discovered and least-characterised islet autoantibodies. In combination with autoantibodies to several other islet antigens, including insulin, ZnT8A help predict risk of future type 1 diabetes. Often, ZnT8A appear later in the pathogenic process leading to type 1 diabetes, suggesting that the antigen is recognised as part of the spreading, rather than the initial, autoimmune response. The development of autoantibodies to different forms of ZnT8 depends on the genotype of an individual for a polymorphic ZnT8 residue. This genetic variant is associated with susceptibility to type 2 but not type 1 diabetes. Levels of ZnT8A often fall rapidly after diagnosis while other islet autoantibodies can persist for many years. In this review, we consider the contribution made by ZnT8 to our understanding of type 1 diabetes over the past decade and what remains to be investigated in future research.

Childhood thyroid autoimmunity and relation to islet autoantibodies in children at risk for type 1 diabetes in the diabetes prediction in skåne (DiPiS) study

BACKGROUND

The aim was to determine prevalence and age at seroconversion of thyroid autoimmunity in relation to islet autoantibodies, gender and HLA-DQ genotypes in children with increased risk for type 1 diabetes followed from birth.

METHODS

In 10-year-old children (n = 1874), blood samples were analysed for autoantibodies against thyroid peroxidase (TPOAb), thyroglobulin (TGAb), glutamic acid decarboxylase 65 (GADA), Zink transporter 8 (ZnT8R/W/QA), insulinoma-associated protein-2 (IA-2A), insulin (IAA) and HLA-DQ genotypes. Prospectively collected samples from 2 years of age were next analysed for TPOAb, and TGAb and, finally, in confirming samples at 11-16 years of age along with TSH and FT4. Frequencies were tested with Chi-square or Fischer's exact tests, autoantibody levels with Wilcoxon and correlations between autoantibody levels with Spearman's rank correlation test.

RESULTS

The prevalence of thyroid autoimmunity was 6.9%, overrepresented in girls (p < .001) also having higher TPOAb levels at 10 years (p = .049). TPOAb was associated with GADA (p = .002), ZnT8R/W/QA (p = .001) and IA-2A (p = .001) while TGAb were associated with ZnT8R/W/QA (p = .021). In boys only, TPOAb were associated with GADA (p = .002), IA-2A (p = .001), ZnT8R/W/QA (p = .001) and IAA (p = .009), and TGAb with GADA (p = .013), IA-2A (p = .005) and ZnT8R/W/QA (p = .003). Levels of IA-2A correlated to both TPOAb (p = .021) and to TGAb (p = .011). In boys only, levels of GADA and TGAb correlated (p = .009 as did levels of IA-2A and TPOAb (p = .013). The frequency and levels of thyroid autoantibodies increased with age. At follow-up, 22.3% had abnormal thyroid function or were treated with thyroxine.

CONCLUSIONS

Thyroid autoimmunity and high TPOAb levels were more common in girls. In contrast, in boys only, there was a strong association with as well as correlation between levels of thyroid and islet autoantibodies. It is concluded that while girls may develop autoimmune thyroid disease (AITD) independent of islet autoantibodies, the risk for thyroid disease in boys may be linked to concomitant islet autoimmunity.

Eleven Amino Acids of HLA-DRB1 and Fifteen Amino Acids of HLA-DRB3, 4, and 5 Include Potentially Causal Residues Responsible for the Risk of Childhood Type 1 Diabetes

Next-generation targeted sequencing of HLA-DRB1 and HLA-DRB3, -DRB4, and -DRB5 (abbreviated as DRB345) provides high resolution of functional variant positions to investigate their associations with type 1 diabetes risk and with autoantibodies against insulin (IAA), GAD65 (GADA), IA-2 (IA-2A), and ZnT8 (ZnT8A). To overcome exceptional DR sequence complexity as a result of high polymorphisms and extended linkage disequilibrium among the DR loci, we applied a novel recursive organizer (ROR) to discover disease-associated amino acid residues. ROR distills disease-associated DR sequences and identifies 11 residues of DRB1, sequences of which retain all significant associations observed by DR genes. Furthermore, all 11 residues locate under/adjoining the peptide-binding groove of DRB1, suggesting a plausible functional mechanism through peptide binding. The 15 residues of DRB345, located respectively in the β49-55 homodimerization patch and on the face of the molecule shown to interact with and bind to the accessory molecule CD4, retain their significant disease associations. Further ROR analysis of DR associations with autoantibodies finds that DRB1 residues significantly associated with ZnT8A and DRB345 residues with GADA. The strongest association is between four residues (β14, β25, β71, and β73) and IA-2A, in which the sequence ERKA confers a risk association (odds ratio 2.15, P = 10^-18), and another sequence, ERKG, confers a protective association (odds ratio 0.59, P = 10^-11), despite a difference of only one amino acid. Because motifs of identified residues capture potentially causal DR associations with type 1 diabetes, this list of residuals is expected to include corresponding causal residues in this study population.

Prevalence of islet autoantibodies in Thai juvenile-onset type 1 diabetes

BACKGROUND

Type 1 diabetes mellitus (T1DM) is caused by autoimmune destruction of islet β-cells of the pancreas. There are overlapping phenotypes in a significant proportion of youth with type 1 and 2 diabetes. Thus, positive pancreatic autoantibodies are helpful to diagnose T1DM. Zinc transporter 8 antibody (ZnT8A) is a recently identified autoantibody in T1DM and no data on ZnT8A in the Thai population have been reported. The aim of this study was therefore to estimate the prevalence of ZnT8A in Thai juvenile-onset T1DM and to evaluate its diagnostic value relative to glutamic acid decarboxylase and insulinoma-2 antigen antibodies (GADA and IA2A).

METHODS

In this cross-sectional study, patients with T1DM diagnosed before age 15 years, and disease duration <10 years were enrolled. Serum ZnT8A, GADA, and IA2A were measured using commercial enzyme-linked immunosorbent assay kits.

RESULTS

The subjects consisted of 81 youths (30 boys, 51 girls) aged 12.3 ± 4.5 years with T1DM. The median diabetes duration was 3 years (range, 0-10 years). The prevalence of ZnT8A, GADA, and IA2A was 54.3%, 75.3%, and 45.7%, respectively. ZnT8A were detected in 16% of T1DM patients negative for both GADA and IA2A. A combination of ZnT8A, GADA and IA2A could detect 80.2% of patients with T1DM. Combined use of ZnT8A and GADA identified 100% of antibody-positive patients.

CONCLUSION

The prevalence of ZnT8A in Thai juvenile-onset T1DM appears to be higher than in previous studies from Asia. ZnT8A could replace IA2A as an autoimmunity marker in Thai pediatric T1DM patients, with better diagnostic performance.

Influence of early-life parental severe life events on the risk of type 1 diabetes in children: the DiPiS study

AIMS

Stress and severe life events (SLEs) modify autoimmune disease susceptibility. Here, we aimed to establish if SLEs reported by parents during the first 2 years of life influence the risk of developing type 1 diabetes (T1D) using data from the prospective Diabetes Prediction in Skåne (DiPiS) study.

METHODS

Prospective questionnaire data recorded at 2 months (n = 23,187) and 2 years of age (n = 3784) from the DiPiS cohort of children were included in the analysis. SLEs were analyzed both by groups and as a combined variable. A Cox proportional hazards model was used to calculate hazard ratios (HRs) for T1D diagnosis for the total cohort and for the HLA-DQ2/8 high-risk population. Affected first-degree relatives, HLA-DQ risk group, paternal education level, and parents' country of birth were included as covariates.

RESULTS

There was a significantly increased risk of T1D in children with SLEs occurring during the child's first 2 years of life for both the total cohort (HR 1.67; 95% CI 1.1, 2.7; p = 0.03) and the DQ2/8 cohort (HR 2.2; 95% CI 1.1, 4.2; p = 0.018). Subgroup analysis of events related to unemployment, divorce, or family conflict showed a significant hazard for these events occurring both during and after pregnancy in the DQ2/8 cohort (HR 2.17; 95% CI 1.1, 4.3; p = 0.03 and HR 4.98; 95% CI 2.3, 11; p < 0.001, respectively) and after pregnancy in the total cohort (multiple regression HR 2.07; 95% CI 1.01, 4.2; p = 0.047).

CONCLUSIONS

Children of parents experiencing an SLE during the child's first 2 years of life were at increased risk of T1D. Further studies including those measuring immune and stress-related biomarkers are necessary to validate the findings.

The Better Diabetes Diagnosis (BDD) study - A review of a nationwide prospective cohort study in Sweden

The incidence of type 1 diabetes (T1D) in Sweden is one of the highest in the world. However, the possibility of other types of diabetes must also be considered. In addition, individuals with T1D constitute a heterogeneous group. A precise classification of diabetes is a prerequisite for optimal outcome. For precise classification, knowledge on the distribution of genetic factors, biochemical markers and clinical features in individuals with new onset of diabetes is needed. The Better Diabetes Diagnosis (BDD), is a nationwide study in Sweden with the primary aim to facilitate a more precise classification and diagnosis of diabetes in order to enable the most adequate treatment for each patient. Secondary aims include identification of risk factors for diabetes-related co-morbidities. Since 2005, data on almost all children and adolescents with newly diagnosed diabetes in Sweden are prospectively collected and including heredity of diabetes, clinical symptoms, levels of C peptide, genetic analyses and detection of autoantibodies. Since 2011, analyses of HLA profile, autoantibodies and C peptide levels are part of clinical routine in Sweden for all pediatric patients with suspected diagnosis of diabetes. In this review, we present the methods and main results of the BDD study so far and discuss future aspects.

Building and validating a prediction model for paediatric type 1 diabetes risk using next generation targeted sequencing of class II HLA genes

AIM

It is of interest to predict possible lifetime risk of type 1 diabetes (T1D) in young children for recruiting high-risk subjects into longitudinal studies of effective prevention strategies.

METHODS

Utilizing a case-control study in Sweden, we applied a recently developed next generation targeted sequencing technology to genotype class II genes and applied an object-oriented regression to build and validate a prediction model for T1D.

RESULTS

In the training set, estimated risk scores were significantly different between patients and controls (P = 8.12 × 10^-92 ), and the area under the curve (AUC) from the receiver operating characteristic (ROC) analysis was 0.917. Using the validation data set, we validated the result with AUC of 0.886. Combining both training and validation data resulted in a predictive model with AUC of 0.903. Further, we performed a "biological validation" by correlating risk scores with 6 islet autoantibodies, and found that the risk score was significantly correlated with IA-2A (Z-score = 3.628, P < 0.001). When applying this prediction model to the Swedish population, where the lifetime T1D risk ranges from 0.5% to 2%, we anticipate identifying approximately 20 000 high-risk subjects after testing all newborns, and this calculation would identify approximately 80% of all patients expected to develop T1D in their lifetime.

CONCLUSION

Through both empirical and biological validation, we have established a prediction model for estimating lifetime T1D risk, using class II HLA. This prediction model should prove useful for future investigations to identify high-risk subjects for prevention research in high-risk populations.

Early prediction of autoimmune (type 1) diabetes

Underlying type 1 diabetes is a genetic aetiology dominated by the influence of specific HLA haplotypes involving primarily the class II DR-DQ region. In genetically predisposed children with the DR4-DQ8 haplotype, exogenous factors, yet to be identified, are thought to trigger an autoimmune reaction against insulin, signalled by insulin autoantibodies as the first autoantibody to appear. In children with the DR3-DQ2 haplotype, the triggering reaction is primarily against GAD signalled by GAD autoantibodies (GADA) as the first-appearing autoantibody. The incidence rate of insulin autoantibodies as the first-appearing autoantibody peaks during the first years of life and declines thereafter. The incidence rate of GADA as the first-appearing autoantibody peaks later but does not decline. The first autoantibody may variably be followed, in an apparently non-HLA-associated pathogenesis, by a second, third or fourth autoantibody. Although not all persons with a single type of autoantibody progress to diabetes, the presence of multiple autoantibodies seems invariably to be followed by loss of functional beta cell mass and eventually by dysglycaemia and symptoms. Infiltration of mononuclear cells in and around the islets appears to be a late phenomenon appearing in the multiple-autoantibody-positive with dysglycaemia. As our understanding of the aetiology and pathogenesis of type 1 diabetes advances, the improved capability for early prediction should guide new strategies for the prevention of type 1 diabetes.

Thyroid and Islet Autoantibodies Predict Autoimmune Thyroid Disease at Type 1 Diabetes Diagnosis

CONTEXT

Screening of autoimmune thyroid disease in children with type 1 diabetes is important but varies between clinics.

OBJECTIVE

To determine the predictive value of thyroid autoantibodies, thyroid function, islet autoantibodies, and HLA-DQ at diagnosis of type 1 diabetes for autoimmune thyroid disease during follow-up.

SETTING

Forty-three Swedish pediatric endocrinology units.

DESIGN, PATIENTS, AND MAIN OUTCOME MEASURES

At diagnosis of type 1 diabetes, autoantibodies against thyroid peroxidase (TPOAb), thyroglobulin (TGAb), glutamic acid decarboxylase (GADA), insulin, insulinoma-associated protein-2, and 3 variants of zinc transporter 8 (ZnT8W/R/QA) HLA-DQA1-B1 genotypes and thyroid function were analyzed in 2433 children. After 5.1 to 9.5 years, information on thyroxine treatment was gathered from the Swedish National Board of Health and Welfare's Prescribed Drug Register.

RESULTS

Thyroxine was prescribed to 6% of patients. In patients <5 years of age, female sex [hazard ratio (HR) = 4.60; P = 0.008] and GADA (HR = 5.80; P = 0.02) were predictors. In patients 5 to 10 years old, TPOAb (HR = 20.56; P < 0.0001), TGAb (HR = 3.40; P = 0.006), and thyroid-stimulating hormone (TSH) (HR = 3.64; P < 0.001) were predictors, whereas in 10 to 15 year olds, TPOAb (HR = 17.00; P < 0.001) and TSH (HR = 4.11; P < 0.001) predicted thyroxine prescription.

CONCLUSION

In addition to TPOAb and TSH, GADA at diagnosis of type 1 diabetes is important for the prediction of autoimmune thyroid disease in children <5 years of age.

Importance of Zinc Transporter 8 Autoantibody in the Diagnosis of Type 1 Diabetes in Latin Americans

There is a scarcity of data of zinc transporter-8 autoantibody (ZnT8A) on mixed populations such as Brazilian. Therefore, we evaluated the relevance of ZnT8A for type 1 diabetes (T1D) diagnosis and the role of ZnT8 coding gene (SLC30A8) in T1D predisposition. Patients with T1D (n = 629; diabetes duration = 11 (6-16) years) and 651 controls were genotyped for SLC30A8 rs16889462 and rs2466295 variants (BeadXpress platform). ZnT8 triple antibody was measured by ELISA; glutamic acid decarboxylase (GAD65A) and protein tyrosine phosphatase (IA-2A) autoantibodies by radioimmunoassay.

RESULTS

Znt8A was detected in 68.7% of recent-onset T1D patients and 48.9% of the entire patient cohort, similar to GAD65A (68.3% and 47.2%) and IA-2A (64.8% and 42.4%) positivities respectively. ZnT8A was the only antibody in 8.4% of patients. Znt8A and IA2A frequencies and titers were independent of gender and ethnicity, whereas GAD65A titers were greater in females. The diabetes duration-dependent decline in ZnT8A frequency was similar to GAD65A and IA-2A. The SLC30A8 rs2466293 AG + GG genotypes were associated with T1D risk in non-European descents (56.2% × 42.9%; p = 0.018), and the GG genotype with higher ZnT8A titers in recent-onset T1D: 834.5 IU/mL (711.3-2190.0) × 281 IU/mL (10.7-726.8); p = 0.027. Conclusion ZnT8A detection increases T1D diagnosis rate even in mixed populations. SLC30A8 rs2466293 was associated with T1D predisposition in non-European descents.

An Increased Diagnostic Sensitivity of Truncated GAD65 Autoantibodies in Type 1 Diabetes May Be Related to HLA-DQ8

N-terminally truncated (96-585) GAD65 (tGAD65) autoantibodies may better delineate type 1 diabetes than full-length GAD65 (fGAD65) autoantibodies. We aimed to compare the diagnostic sensitivity and specificity between fGAD65 and tGAD65 autoantibodies for type 1 diabetes in relation to HLA-DQ. Sera from children and adolescents with newly diagnosed type 1 diabetes (n = 654) and healthy control subjects (n = 605) were analyzed in radiobinding assays for fGAD65 (fGADA), tGAD65 (tGADA), and commercial ¹²⁵I-GAD65 (RSRGADA) autoantibodies. The diagnostic sensitivity and specificity in the receiver operating characteristic curve did not differ between fGADA and tGADA. At the optimal cutoff, the diagnostic sensitivity for fGADA was lower than tGADA at similar diagnostic specificities. In 619 patients, 64% were positive for RSRGADA compared with 68% for fGADA and 74% for tGADA. Using non-DQ2/non-DQ8 patients as reference, the risk of being diagnosed with fGADA and tGADA was increased in patients with DQ2/2 and DQ2/8. Notably, logistic regression analysis suggested that DQ8/8 patients had an increased risk to be diagnosed with tGADA (P = 0.003) compared with fGADA (P = 0.09). tGADA had a higher diagnostic sensitivity for type 1 diabetes than both fGADA and RSRGADA. As DQ8/8 patients represent 10-11% of patients with newly diagnosed type 1 diabetes <18 years of age, tGADA analysis should prove useful for disease classification.

An Object-Oriented Regression for Building Disease Predictive Models with Multiallelic HLA Genes

Recent genome-wide association studies confirm that human leukocyte antigen (HLA) genes have the strongest associations with several autoimmune diseases, including type 1 diabetes (T1D), providing an impetus to reduce this genetic association to practice through an HLA-based disease predictive model. However, conventional model-building methods tend to be suboptimal when predictors are highly polymorphic with many rare alleles combined with complex patterns of sequence homology within and between genes. To circumvent this challenge, we describe an alternative methodology; treating complex genotypes of HLA genes as "objects" or "exemplars," one focuses on systemic associations of disease phenotype with "objects" via similarity measurements. Conceptually, this approach assigns disease risks base on complex genotype profiles instead of specific disease-associated genotypes or alleles. Effectively, it transforms large, discrete, and sparse HLA genotypes into a matrix of similarity-based covariates. By the Kernel representative theorem and machine learning techniques, it uses a penalized likelihood method to select disease-associated exemplars in building predictive models. To illustrate this methodology, we apply it to a T1D study with eight HLA genes (HLA-DRB1, HLA-DRB3, HLA-DRB4, HLA-DRB5, HLA-DQA1, HLA-DQB1, HLA-DPA1, and HLA-DPB1) to build a predictive model. The resulted predictive model has an area under curve of 0.92 in the training set, and 0.89 in the validating set, indicating that this methodology is useful to build predictive models with complex HLA genotypes.

Altered regulatory T cell phenotype in latent autoimmune diabetes of the adults (LADA)

Latent autoimmune diabetes of the adults (LADA) accounts for up to 12% of all patients with diabetes. Initially the disease resembles type 2 diabetes (T2D); however, the typical presence of β cell autoantibodies indicates an autoimmune basis of LADA. While dysfunctional regulatory T cells (Tregs ) have been implicated in autoimmune diabetes, these cells have been scarcely studied in LADA. The aim of this study was to investigate the frequency and phenotype of circulating Tregs in LADA patients early during disease progression. Flow cytometric analysis was performed on whole blood and peripheral mononuclear cells (PBMC) from patients diagnosed with LADA prior to insulin deficiency (n = 39) and from healthy volunteers (n = 20). Overall, we found the frequency and activation status of peripheral putative Tregs to be altered in LADA patients compared to healthy controls. While total T cells and CD4(+) T cells expressing high levels of CD25 (CD4(+) CD25(hi) ) were unchanged, the frequency and total numbers of CD4(+) T cells expressing an intermediate level of CD25 (CD4(+) CD25(int) ) were decreased in LADA patients. Interestingly, the expression of the Treg -specific marker forkhead box protein 3 (FoxP3), as well as the activation and memory makers CD69, cytotoxic T lymphocyte associated antigen 4 (CTLA-4), CCR4 and CD45RO were increased in CD4(+) CD25(+) T cells of the patients. Our data depict phenotypical changes in T cells of LADA patients that may reflect a derangement in peripheral immune regulation contributing to the slow process leading to insulin-dependent diabetes in these patients.

A Swedish approach to the prevention of type 1 diabetes

BACKGROUND

The autoimmune destruction of beta cells, resulting in clinical type 1 diabetes, may start early in life and last for several months or years. During this period of time, we have an opportunity to try to prevent or delay further beta-cell destruction and clinical onset of type 1 diabetes.

OBJECTIVES

Ongoing prediction and prevention studies in Skåne, Sweden are described.

METHODS

During September 2000 to August 2004, 35 000 children were screened at birth for genetic type 1 diabetes risk in the Diabetes Prediction in Skåne Study (DiPiS). In August 2004, the screening continued within the Enviromnental Determinants of Diabetes in the Young study (TEDDY). In the clinical trial Diabetes Prevention - Immune Tolerance (DiAPREV-IT), children with multiple islet autoimmunity have been included to investigate if immune tolerance with Alum-formulated GAD65 may prevent further beta-cell loss.

RESULTS

In DiPiS and TEDDY, a large number of children are followed in order to find the factors that trigger the autoimmune process leading to type 1 diabetes. Children followed in the studies develop diabetes at an early stage of disease, with few symptoms and a low frequency of diabetes ketoacidosis. DiAPREV-IT is still blinded and results will be available in December 2016.

CONCLUSION

Large prospective studies will be needed to understand the complex process leading to type 1 diabetes. Secondary prevention may be possible in children with islet autoimmunity, but the studies are complicated by the variability of glucose metabolism and beta-cell loss.

Environmental factors in the etiology of type 1 diabetes, celiac disease, and narcolepsy

The etiology of human leukocyte antigen (HLA)-associated organ-specific autoimmune diseases is incomplete. In type 1 diabetes and celiac disease, the strongest associations are with the HLA-DR3-DQ2 and DR4-DQ8 haplotypes, whereas the DQB1*06:02 allele has a strong negative association. In contrast, narcolepsy, especially as recently triggered by the Pandemrix(®) H1N1 vaccine (GlaxoKlineSmith (GSK), Brentford, Middlesex, UK), did not seem to develop without at least one copy of the latter allele. The overall hypothesis is that the role of these different HLA haplotypes, especially in Finland and Sweden, is related to the immune response to infectious agents that are common in these two populations. The high incidence of both type 1 diabetes and celiac disease in Scandinavia may be the result of the HLA-DR3-DQ2 and DR4-DQ8 haplotypes, and the DQB1*06:02 allele are common because they protected people from succumbing to common infections. The timing of dissecting the autoimmune response is critical to understand the possible role of environmental factors. First, an etiological trigger may be a common virus infecting beta cells or with antigens inducing beta-cell cross reactivity. Second, an autoimmune reaction may ensue, perhaps in response to beta-cell apoptosis or autophagy, resulting in autoantigen-specific T cells and autoantibodies. It is critical in at-risk children to dissect the immune response prior to the appearance of autoantibodies in order to identify cellular reactions in response to environmental factors that are able to induce an HLA-associated immune reaction.

Zinc transporter 8 autoantibodies assessment in daily practice

OBJECTIVES

Zinc transporter 8 (ZnT8) is specifically expressed in the pancreatic β-cell and is more restricted in its tissue distribution than other auto-antigens as glutamic acid decarboxylase 65 (GAD₆₅) and insulinoma-associated antigen-2 (IA2). ZnT8 autoantibodies (ZnT8A) assessment allows identifying rapid progression to clinical onset of the disease. We evaluated the prevalence of ZnT8A in adults of different ethnic and phenotypic groups and analyzed its potential utility as additional marker of autoimmunity in daily practice.

METHODS

ZnT8A, GADA and IA2A were assessed using enzyme-linked immune-sorbent assay (ELISA) in 160 controls and 216 diabetic subjects. 105 were of type 1 diabetes (T1D), 17 had Latent Autoimmune Diabetes of Adults (LADA), 38 were type 2 diabetic (T2D) and 56 had ketosis-prone diabetes (KPD). 82 patients were newly diagnosed cases.

RESULTS

ZnT8A were detected in 1% of controls and were not found in any of our 38 T2D subjects or 56 KPD subjects. In contrast, ZnT8A were detected in 18% of LADA subjects and in 38% of T1D subjects. A slight difference of percentage of ZnT8A positivity was found among our T1D ethnic groups. ZnT8A were positive in 41% of patients positive for GADA and 67% of patients positive for IA2A. The percentage of stratification achieved 91% when GADA, IA2A and ZnT8A were assessed simultaneously.

CONCLUSIONS

Results obtained for ZnT8A measurement using ELISA were consistent with previous data. Such investigation could improve the risk stratification and would be integrated in our daily practice.

Current and Future Clinical Applications of Zinc Transporter-8 in Type 1 Diabetes Mellitus

Objective:

To evaluate the utility of zinc transporter-8 (ZnT8) in the improvement of type 1 diabetes mellitus (T1DM) diagnosis and prediction, and to explore whether ZnT8 is a potential therapeutic target in T1DM.

Data Sources:

A search was conducted within the medical database PubMed for relevant articles published from 2001 to 2015. The search terms are as follows: “ZnT8,” “type 1 diabetes,” “latent autoimmune diabetes in adults,” “type 2 diabetes,” “islet autoantibodies,” “zinc supplement,” “T cells,” “β cell,” “immune therapy.” We also searched the reference lists of selected articles.

Study Selection:

English-language original articles and critical reviews concerning ZnT8 and the clinical applications of islet autoantibodies in diabetes were reviewed.

Results:

The basic function of ZnT8 is maintaining intracellular zinc homeostasis, which modulates the process of insulin biosynthesis, storage, and secretion. Autoantibodies against ZnT8 (ZnT8A) and ZnT8-specific T cells are the reliable biomarkers for the identification, stratification, and characterization of T1DM. Additionally, the results from the animal models and clinical trials have shown that ZnT8 is a diabetogenic antigen, suggesting the possibility of ZnT8-specific immunotherapy as an alternative for T1DM therapy.

Conclusions:

ZnT8 is a novel islet autoantigen with a widely potential for clinical applications in T1DM. However, before the large-scale clinical applications, there are still many problems to be solved.

Next-Generation Sequencing Reveals That HLA-DRB3, -DRB4, and -DRB5 May Be Associated With Islet Autoantibodies and Risk for Childhood Type 1 Diabetes

The possible contribution of HLA-DRB3, -DRB4, and -DRB5 alleles to type 1 diabetes risk and to insulin autoantibody (IAA), GAD65 (GAD autoantibody [GADA]), IA-2 antigen (IA-2A), or ZnT8 against either of the three amino acid variants R, W, or Q at position 325 (ZnT8RA, ZnT8WA, and ZnT8QA, respectively) at clinical diagnosis is unclear. Next-generation sequencing (NGS) was used to determine all DRB alleles in consecutively diagnosed patients ages 1-18 years with islet autoantibody-positive type 1 diabetes (n = 970) and control subjects (n = 448). DRB3, DRB4, or DRB5 alleles were tested for an association with the risk of DRB1 for autoantibodies, type 1 diabetes, or both. The association between type 1 diabetes and DRB1*03:01:01 was affected by DRB3*01:01:02 and DRB3*02:02:01. These DRB3 alleles were associated positively with GADA but negatively with ZnT8WA, IA-2A, and IAA. The negative association between type 1 diabetes and DRB1*13:01:01 was affected by DRB3*01:01:02 to increase the risk and by DRB3*02:02:01 to maintain a negative association. DRB4*01:03:01 was strongly associated with type 1 diabetes (P = 10(-36)), yet its association was extensively affected by DRB1 alleles from protective (DRB1*04:03:01) to high (DRB1*04:01:01) risk, but its association with DRB1*04:05:01 decreased the risk. HLA-DRB3, -DRB4, and -DRB5 affect type 1 diabetes risk and islet autoantibodies. HLA typing with NGS should prove useful to select participants for prevention or intervention trials.

Neuropeptide Y is a minor autoantigen in newly diagnosed type 1 diabetes patients

BACKGROUND

Autoantibodies (A) against Neuropeptide Y (NPY), was reported in 9% newly diagnosed type 1 diabetes (T1D) patients. A single nucleotide polymorphism (SNP) at rs16139 (T1128C) within the NPY-gene identified an amino acid substitution from leucine (L) to proline (P) (L7P) associated with both glucose tolerance and type 2 diabetes. We aimed to determine: (i) the influence of autoantibodies to leucine neuropeptide Y (NPY-LA) and autoantibodies to proline neuropeptide Y (NPY-PA) on the diagnostic sensitivity of type 1 diabetes (T1D), (ii) the association of NPYA with major islet autoantibodies, and (iii) the association of NPYA with HLA-DQ genotypes in newly diagnosed T1D patients.

METHODS

Serum from the HLA-DQ typed T1D patients (n = 673; median age 10 yr) from Skåne, Sweden, were analyzed for autoantibodies against NPY-L and NPY-P in a radioligand binding assay, and against glutamic acid decarboxylase 65 (GAD65), insulin, insulinoma associated protein-2 (IA-2), and zinc transporter 8 (ZnT8) in addition to islet cell antibodies (ICA). A total of 1006 subjects (median age 9 yr) were used as controls.

RESULTS

A total of 9.2% (n = 62) of the T1D patients were positive for NPY-LA (p < 0.001) and 7.6% (n = 51) for NPY-PA (p < 0.001) compared to 1.1% (n = 11) in controls. The NPY-LA and NPY-PA appeared together (κ = 0.63; p < 0.001) and the median levels correlated (R² = 0.603; p < 0.001). T1D patients diagnosed after 10 yr of age were at an increased risk for NPYA at diagnosis [odds ratio (OR = 2.46; 95% CI 1.46-4.16; p = 0.001)] adjusted for age at diagnosis, gender, autoantibody positivity, and HLA.

CONCLUSIONS

NPY is a minor autoantigen in children with newly diagnosed T1D. Therefore, NPY autoantibodies may be investigated in T1D autoimmunity.

Non-HLA type 1 diabetes genes modulate disease risk together with HLA-DQ and islet autoantibodies

The possible interrelations between HLA-DQ, non-HLA single nucleotide polymorphisms (SNPs) and islet autoantibodies were investigated at clinical onset in 1-34 year old type 1 diabetes (T1D) patients (n=305) and controls (n=203). Among the non-HLA SNPs reported by the Type 1 Diabetes Genetics Consortium, 24% were supported in this Swedish replication set including that the increased risk of minor PTPN22 allele and high risk HLA was modified by GAD65 autoantibodies. The association between T1D and the minor AA+AC genotype in ERBB3 gene was stronger among IA-2 autoantibody-positive patients (comparison p=0.047). The association between T1D and the common insulin (AA) genotype was stronger among insulin autoantibody (IAA)-positive patients (comparison p=0.008). In contrast, the association between T1D and unidentified 26471 gene was stronger among IAA-negative (comparison p=0.049) and IA-2 autoantibody-negative (comparison p=0.052) patients. Finally, the association between IL2RA and T1D was stronger among IAA-positive than among IAA-negative patients (comparison p=0.028). These results suggest that the increased risk of T1D by non-HLA genes is often modified by both islet autoantibodies and HLA-DQ. The interactions between non-HLA genes, islet autoantibodies and HLA-DQ should be taken into account in T1D prediction studies as well as in prevention trials aimed at inducing immunological tolerance to islet autoantigens.

Changes in Zinc Transporter 8 Autoantibodies Following Type 1 Diabetes Onset: The Type 1 Diabetes Genetics Consortium Autoantibody Workshop

Zinc transporter 8 autoantibodies (ZnT8A) were analyzed in sera from 1,504 subjects as part of the Type 1 Diabetes Genetics Consortium (T1DGC) Autoantibody Workshop. For these participants with type 1 diabetes (T1D), samples were collected within 3 years of T1D diagnosis. ZnT8A were detected in 862 subjects (57.3%), with the highest frequencies and median titers being associated with the shortest duration of disease. ZnT8A were present at similar frequencies in non-Hispanic whites, non-Hispanic blacks, and Hispanics, but significantly less prevalent in those of Asian ancestry. Sera containing ZnT8A selectively recognizing at least one of the SLC30A8 single nucleotide polymorphisms (encoding ZnT8A) were detected in all populations; however, Trp-specific sera were much less frequent in non-Hispanic blacks, consistent with the anticipated lower frequency of the SLC30A8 rs13266634 T allele in African American populations. ZnT8A positivity was associated with HLA-DQ8, but this was primarily due to the DRB1*0404-DQ8 haplotype. This was in contrast to autoantibodies to IA-2 that were strongly associated with DRB1*0401-DQ8. These effects appeared essentially independent of racial or ethnic background. The DRB1*0401-DQ8 and DRB1*0404-DQ8 haplotypes were associated with T1D subjects positive for GAD65, IA-2, and ZnT8A. In contrast to DRB1*0401-DQ8, there was no significant association of DRB1*0404-DQ8 with single or dual autoantibody positivity. The DRB1*0404-DQ8 haplotype was also associated with T1D subjects whose sera recognized both polymorphic variants of zinc transporter 8, an effect not seen for DRB1*0401-DQ8.

Staging presymptomatic type 1 diabetes: a scientific statement of JDRF, the Endocrine Society, and the American Diabetes Association

Insights from prospective, longitudinal studies of individuals at risk for developing type 1 diabetes have demonstrated that the disease is a continuum that progresses sequentially at variable but predictable rates through distinct identifiable stages prior to the onset of symptoms. Stage 1 is defined as the presence of β-cell autoimmunity as evidenced by the presence of two or more islet autoantibodies with normoglycemia and is presymptomatic, stage 2 as the presence of β-cell autoimmunity with dysglycemia and is presymptomatic, and stage 3 as onset of symptomatic disease. Adoption of this staging classification provides a standardized taxonomy for type 1 diabetes and will aid the development of therapies and the design of clinical trials to prevent symptomatic disease, promote precision medicine, and provide a framework for an optimized benefit/risk ratio that will impact regulatory approval, reimbursement, and adoption of interventions in the early stages of type 1 diabetes to prevent symptomatic disease.

Zinc transporter 8 autoantibodies in patients with type 1 diabetes from a multiethnic population and their first degree relatives

OBJECTIVE

Zinc transporter 8 autoantibodies (ZnT8A) have been poorly studied in non-Caucasian individuals. We aimed to investigate the prevalence of ZnT8 autoantibodies in patients with T1D and their first degree relatives (FDR) from a multiethnic population, as well as its relation with the insulin (INS) or the protein tyrosine phosphatase non-receptor 22 (PTPN22) gene polymorphisms.

SUBJECTS AND METHODS

ZnT8A were analyzed in sera from T1D patients (n = 72, mean age of 30.3 ± 11.4 years) of variable duration (15.7 ± 11.8 years) and their FDR (n = 78, mean age of 18.3 ± 9.1 years) by a triple mix Radioligand Binding Assay (RBA) for the ZnT8 autoantibody (ZnT8-RWQ) variants. SNP (single nucleotide polymorphism) for INS and PTPN22 were genotyped.

RESULTS

The prevalence of ZnT8A was higher in T1D patients than FDR, for ZnT8TripleA (24% vs. 4%,p = 0.001), ZnT8RA (24% vs. 4%, p < 0.001) and ZnT8QA (15% vs. 3%, p = 0.004). All FDR with ZnT8A (n = 3) had at least another positive antibody. Heterozygosis for PTPN22 was associated with a higher frequency of ZnT8TripleA (p = 0.039) and ZnT8RA (p = 0.038).

CONCLUSIONS

ZnT8A is observed in non-Caucasian patients with T1D, even years after the disease onset, as well as in their FDR. In those, there was an overlap between ZnT8A and other T1D antibodies. ZnT8A was associated with PTPN22 polymorphisms. Further longitudinal studies are necessary to elucidate the importance of these findings in the natural history of T1D patients with multiethnic background.

Zinc transporter 8 (ZnT8) autoantibody epitope specificity and affinity examined with recombinant ZnT8 variant proteins in specific ZnT8R and ZnT8W autoantibody-positive type 1 diabetes patients

Variant-specific zinc transporter 8 autoantibodies (ZnT8A) against either arginine (R) or tryptophan (W) at amino acid (aa) position 325 of the zinc transporter 8 (ZnT8) has been identified in type 1 diabetes (T1D) patients. Reciprocal cross-over tests revealed differences in half-maximal binding to indicate variable affinity of patient ZnT8 autoantibodies. Insufficient recombinant ZnT8 variant proteins have precluded detailed analyses of ZnT8 autoantibody affinity. The aims in the present study were to (i) generate recombinant ZnT8R- and ZnT8W-aa275-369 proteins; (ii) test the ZnT8R- and ZnT8W-aa275-369 proteins in reciprocal competitive radiobinding assays (RBA) against ZnT8R- and ZnT8W-aa268-369 labelled with (35) S-methionine; and (iii) determine the specificity and affinity of sera specific for either ZnT8 arginine (R) or ZnT8 tryptophan (W) autoantibodies in newly diagnosed T1D patients. The results demonstrate, first, that it was possible to produce recombinant human MBP-ZnT8-aa275-369 protein purified to homogeneity for RBA reciprocal competition experiments. Secondly, high-titre ZnT8WA sera diluted to half maximal binding showed significant specificity for respective variants of either ZnT8R or ZnT8W. Thirdly, ZnT8WA-positive sera showed high affinity for ZnT8W compared to ZnT8RA for ZnT8R. These data demonstrate that T1D patients may have single amino acid-specific autoantibodies directed against either ZnT8R or ZnT8W and that the autoantibody affinity to the respective variant may be different. Further studies are needed to assess the mechanisms by which variant-specific ZnT8A of variable affinity develop and their possible role in the pathogenic process leading to the clinical onset of T1D.

GADA and anti-ZnT8 complicate the outcome of phenotypic type 2 diabetes of adults

BACKGROUND

A proportion of phenotypic type 2 diabetes (T2D) patients produce pancreatic autoantibodies and a majority of T2D patients develop serious life-disabling complications over time despite the implementation of adequate clinical interventions. This study determined whether the presence of pancreatic autoantibodies (GADA, IA-2A, anti-ZnT8, or ICA) was associated with serious complications or concomitant diseases of adult patients diagnosed with T2D (N = 305).

MAIN RESULTS

In the study population, 22.3% (N = 68) of subjects were positive for at least 1 of the 4 of the markers associated with autoimmune diabetes (presence of pancreatic autoantibody - pAb), followed by GADA (14.1%, N = 43), ICA (8.9%, N = 27), anti-ZnT8 (5.6%, N = 17) and IA-2A (2.0%, N = 6). Logistic regression analysis adjusted for patient's age, gender and duration of T2D revealed that (i) pAb was associated with higher prevalence of adiposity (odds ratio of adjusted regression model (adOR) 2.51, P = 0.032); (ii) pAb, GADA and anti-ZnT8 were associated with autoimmune thyroid disease (adORs 3.07, P = 0.012; 6.29, P < 0.001 and 3.52, P = 0.052, respectively); (iii) pAb and GADA, in particular, were risk factors for neurological complications (adORs 2.10, P = 0.036; 2.76, P = 0.009, respectively) and polyneuropathy in particular (adORs 2.60, P = 0.012; 3.10, P = 0.007, respectively); and (iv) anti-ZnT8 was a risk factor for developing nephropathy (adOR 4.61, P = 0.022). In addition, adiposity was associated with 5.3-year earlier onset of disease (adjusted linear regression model, P = 0.006).

CONCLUSIONS

These results suggest that GADA and anti-ZnT8 are associated with progression of serious T2D complications, including polyneuropathy and nephropathy. In addition, adiposity represents a significant risk for autoimmunity development in T2D patients.

Reduced morbidity at diagnosis and improved glycemic control in children previously enrolled in DiPiS follow-up

AIMS/HYPOTHESIS

Children participating in longitudinal type 1 diabetes prediction studies were reported to have less severe disease at diabetes diagnosis. Our aim was to investigate children who from birth participated in the Diabetes Prediction in Skåne (DiPiS) study for metabolic status at diagnosis and then continued to be followed for 2 yr of regular clinical care.

METHODS

Children, followed in DiPiS before diagnosis, were compared to children in the same birth cohort, who did not participate in follow-up. Metabolic status, symptoms at diagnosis as well as hemoglobin A1c (HbA1c) and doses of insulin at 3, 6, 12, and 24 months after diagnosis were compared.

RESULTS

Children, followed in DiPiS and diagnosed at 2-12 yr of age, had 0.8% (9 mmol/mol) lower HbA1c at diagnosis than those who were not followed (p = 0.006). At diagnosis, fewer DiPiS children had symptoms (p = 0.014) and ketoacidosis at diagnosis were reduced (2% compared to 18%, p = 0.005). During regular clinical care, HbA1c levels for the DiPiS children remained lower both at 12 (0.4% (4 mmol/mol); p = 0.009) and 24 months (0.8% (9 mmol/mol) p  <  0.001) after diagnosis, despite no difference in total daily insulin between the two groups.

CONCLUSIONS

Participation in prospective follow-up before diagnosis of type 1 diabetes leads to earlier diagnosis with fewer symptoms, decreased incidence of ketoacidosis as well as better metabolic control up to 2 yr after diagnosis. Our data indicate that metabolic control at the time of diabetes diagnosis is important for early metabolic control possibly affecting the risk of long-term complications.

Current understanding of ZIP and ZnT zinc transporters in human health and diseases

Zinc transporters, the Zrt-, Irt-like protein (ZIP) family and the Zn transporter (ZnT) family transporters, are found in all aspects of life. Increasing evidence has clarified the molecular mechanism, in which both transporters play critical roles in cellular and physiological functions via mobilizing zinc across the cellular membrane. In the last decade, mutations in ZIP and ZnT transporter genes have been shown to be implicated in a number of inherited human diseases. Moreover, dysregulation of expression and activity of both transporters has been suggested to be involved in the pathogenesis and progression of chronic diseases including cancer, immunological impairment, and neurodegenerative diseases, although comprehensive understanding is far from complete. The diverse phenotypes of diseases related to ZIP and ZnT transporters reflect the multifarious biological functions of both transporters. The present review summarizes the current understanding of ZIP and ZnT transporter functions from the standpoint of human health and diseases. The study of zinc transporters is currently of great clinical interest.

Zinc transporter-8 autoantibodies can replace IA-2 autoantibodies as a serological marker for juvenile onset type 1 diabetes in India

INTRODUCTION

Zinc transporter-8 (ZnT8) is an islet cell secretory granule membrane protein recently identified as an autoantigen in type 1 diabetes (T1D). The aim of this study was to estimate the prevalence of antibodies to ZnT8 (ZnT8A) in juvenile onset T1D and to determine the utility of ZnT8A as an independent marker of autoimmunity either alone in antibody-negative subjects or in conjunction with glutamic acid decarboxylase (GAD) and insulinoma-2 antigen antibodies (GADA and IA2A).

RESEARCH DESIGN

ZnT8A, GADA, and IA2A were measured in sera of consecutive T1D patients (n = 88, age range 2-18 years) within 4 years of diagnosis and 88 sex-matched controls.

RESULTS

The prevalences of GADA, ZnT8a, and IA2A were 64.7%, 31.8% and 19.3%, respectively. In newly diagnosed patients, the frequency of ZnT8A was 45%. ZnT8A were positive in 26% of patients negative for both GADA and IA2A. IA2A were positive only in two patients who were negative for other two antibodies. Combined use of ZnT8A and GADA could detect 97% of antibody positive patients. In receiver operating characteristic (ROC) analysis, the performances of GADA and ZnT8As were better than that of IA2A; and AUCs of GADA, ZnT8A, and IA2A for the prediction of T1D were 0.8, 0.65, and 0.59, respectively.

CONCLUSIONS

ZnT8A complements GADA and increases the diagnostic sensitivity for detection of autoimmunity in juvenile-onset T1D. Inclusion of ZnT8A increases the proportion of patients with antibody positivity to nearly 80%. ZnT8A can replace IA2A as a serological marker for autoimmunity in Indian T1D patients without loss of sensitivity and specificity.

Antibodies to influenza virus A/H1N1 hemagglutinin in Type 1 diabetes children diagnosed before, during and after the SWEDISH A(H1N1)pdm09 vaccination campaign 2009-2010

We determined A/H1N1-hemagglutinin (HA) antibodies in relation to HLA-DQ genotypes and islet autoantibodies at clinical diagnosis in 1141 incident 0.7-to 18-year-old type 1 diabetes patients diagnosed April 2009-December 2010. Antibodies to (35) S-methionine-labelled A/H1N1 hemagglutinin were determined in a radiobinding assay in patients diagnosed before (n = 325), during (n = 355) and after (n = 461) the October 2009-March 2010 Swedish A(H1N1)pdm09 vaccination campaign, along with HLA-DQ genotypes and autoantibodies against GAD, insulin, IA-2 and ZnT8 transporter. Before vaccination, 0.6% patients had A/H1N1-HA antibodies compared with 40% during and 27% after vaccination (P < 0.0001). In children <3 years of age, A/H1N1-HA antibodies were found only during vaccination. The frequency of A/H1N1-HA antibodies during vaccination decreased after vaccination among the 3 < 6 (P = 0.006) and 13 < 18 (P = 0.001), but not among the 6 < 13-year-olds. HLA-DQ2/8 positive children <3 years decreased from 54% (15/28) before and 68% (19/28) during, to 30% (9/30) after vaccination (P = 0.014). Regardless of age, DQ2/2; 2/X (n = 177) patients had lower frequency (P = 0.020) and levels (P = 0.042) of A/H1N1-HA antibodies compared with non-DQ2/2; 2/X (n = 964) patients. GADA frequency was 50% before, 60% during and 51% after vaccination (P = 0.009). ZnT8QA frequency increased from 30% before to 34% during and 41% after vaccination (P = 0.002). Our findings suggest that young (<3 years) along with DQ2/2; 2/X patients were low responders to Pandemrix(®) . As the proportion of DQ2/8 patients <3 years of age decreased after vaccination and the frequencies of GADA and ZnT8QA were enhanced, it cannot be excluded that the vaccine affected clinical onset of type 1 diabetes.

The zinc transporter, Slc39a7 (Zip7) is implicated in glycaemic control in skeletal muscle cells

Dysfunctional zinc signaling is implicated in disease processes including cardiovascular disease, Alzheimer's disease and diabetes. Of the twenty-four mammalian zinc transporters, ZIP7 has been identified as an important mediator of the ‘zinc wave’ and in cellular signaling. Utilizing siRNA targeting Zip7 mRNA we have identified that Zip7 regulates glucose metabolism in skeletal muscle cells. An siRNA targeting Zip7 mRNA down regulated Zip7 mRNA 4.6-fold (p = 0.0006) when compared to a scramble control. This was concomitant with a reduction in the expression of genes involved in glucose metabolism including Agl, Dlst, Galm, Gbe1, Idh3g, Pck2, Pgam2, Pgm2, Phkb, Pygm, Tpi1, Gusb and Glut4. Glut4 protein expression was also reduced and insulin-stimulated glycogen synthesis was decreased. This was associated with a reduction in the mRNA expression of Insr, Irs1 and Irs2, and the phosphorylation of Akt. These studies provide a novel role for Zip7 in glucose metabolism in skeletal muscle and highlight the importance of this transporter in contributing to glycaemic control in this tissue.