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Project description:Type 1 diabetes (T1D) usually has a preclinical phase identified by the presence of circulating autoantibodies to pancreatic islet antigens, and most young children who have multiple autoantibodies progress to diabetes within 10 years. While autoantibodies denote underlying islet autoimmunity, how this process is initiated and then progresses to clinical diabetes on a background of genetic susceptibility is not clearly understood. Only one study has thus far reported changes in gene expression in isolated immune cells associated with progression to islet autoimmunity. We analysed chromatin accessibility by ATAC-seq in CD4+ T cells in four genetically at-risk children with islet autoantibodies who progressed to diabetes in ≤ 3 years (‘progressors’), compared to five at-risk children matched for sex, age and HLA who had not progressed (‘non-progressors). From ATAC-seq data, we generated the first map of chromatin accessibility in T cells of islet autoantibody-positive children. Progression was associated with a subtle reconfiguration of regulatory chromatin regions, and some of the chromatin conformation changes could be linked to progression associated expression changes at cytotoxic genes.
2022-03-09 | GSE185189 | GEO
Project description:Type 1 diabetes (T1D) usually has a preclinical phase identified by the presence of circulating autoantibodies to pancreatic islet antigens, and most young children who have multiple autoantibodies progress to diabetes within 10 years. While autoantibodies denote underlying islet autoimmunity, how this process is initiated and then progresses to clinical diabetes on a background of genetic susceptibility is not clearly understood. We analysed gene expression by RNA-seq in four types of immune cells from five genetically at-risk children with islet autoantibodies who progressed to diabetes in ≤ 3 years (‘progressors’) and in five at-risk children matched for sex, age and HLA who had not progressed to diabetes (‘non-progressors’).
2022-03-09 | GSE185190 | GEO
Project description:Chromatin accessibility changes underlying progression from islet autoantibody positivity to type 1 diabetes
| PRJNA767892 | ENA
Project description:Transcriptional and chromatin accessibility changes underlying progression from islet autoantibody positivity to type 1 diabetes
| PRJNA767889 | ENA
Project description:Transcriptional changes underlying progression from islet autoantibody positivity to type 1 diabetes
| PRJNA767893 | ENA
Project description:Islet autoantibodies are typically associated with type 1 diabetes, but have been found in patients diagnosed with type 2 diabetes in whom they are associated with lower adiposity. The significance of autoantibody positivity in overweight and obese patients is not well understood. The aim of this study was to determine the prevalence and clinical significance of islet autoantibodies in overweight/obese adults diagnosed with type 2 diabetes. This study includes 204 participants at one site of the multicenter Look AHEAD (Action for Health in Diabetes) trial (ClinicalTrials.gov identifier: NCT00017953) which randomized overweight/obese adults diagnosed with type 2 diabetes to an intensive lifestyle intervention or diabetes support and education. We measured antibodies to glutamic acid decarboxylase, insulinoma antigen-2, and zinc transporter 8. Participants with and without autoantibodies were compared with respect to baseline clinical features, and longitudinal changes in weight, hemoglobin A1c, and antihyperglycemic medications. We found that 13 participants (6.4%) were autoantibody positive, including six of 47 participants (12.8%) with BMI ≥40 kg/m2. At baseline, autoantibody positive participants had higher HDL cholesterol (1.27 vs. 1.09 mmol/L, p = .034) and lower fasting C-peptide (0.32 vs. 0.57 nmol/L, p = .049). Over four years, autoantibody positive participants lost 5.1 kg more weight than autoantibody negative participants (p = .056). Longitudinal changes in hemoglobin A1c did not differ by autoantibody status, though autoantibody positive participants were more likely to increase the number of antihyperglycemic medications or initiate insulin (p = .011). In conclusion, islet autoantibodies were present in 6.4% of overweight/obese adults with type 2 diabetes including those with severe obesity, and were associated with distinct clinical features. The effect of autoantibody positivity on weight loss interventions requires further study.
| S-EPMC6362362 | biostudies-literature
Project description:AimsThis study aimed to investigate the frequency of islet autoantibody positivity in adult patients with recently diagnosed diabetes in Uganda and its associated characteristics.MethodsAutoantibodies to glutamic acid decarboxylase-65 (GADA), zinc transporter 8 (ZnT8-A), and tyrosine phosphatase (IA-2A) were measured in 534 adult patients with recently diagnosed diabetes. Islet autoantibody positivity was defined based on diagnostic thresholds derived from a local adult population without diabetes. The socio-demographic, clinical, and metabolic characteristics of islet autoantibody-positive and negative participants were then compared. The differences in these characteristics were analysed using the x2 test for categorical data and the Kruskal Wallis test for continuous data. Multivariate analysis was performed to identify predictors of islet autoantibody positivity.ResultsThirty four (6.4%) participants were positive for ≥1 islet autoantibody. GADA, IA-2A and ZnT8-A positivity was detected in 17 (3.2%), 10 (1.9%), and 7 (1.3%) participants, respectively. Compared with those negative for islet autoantibodies, participants positive for islet autoantibodies were more likely to live in a rural area (n = 18, 52.9% Vs n = 127, 25.5%, p = 0.005), to be initiated on insulin therapy (n = 19, 55.9% Vs n = 134, 26.8%, p<0.001), to have a lower median waist circumference (90 [80-99] cm Vs 96 [87-104.8], p = 0.04), waist circumference: height ratio (0.55 [0.50-0.63] vs 0.59 [0.53-0.65], p = 0.03), and fasting C-peptide concentration (0.9 [0.6-1.8] Vs 1.4 [0.8-2.1] ng/ml, p = 0.01). On multivariate analysis, living in a rural area (odds ratio or OR 3.62, 95%CI 1.68-7.80, p = 0.001) and being initiated on insulin therapy (OR 3.61, 95% CI 1.67-7.83, p = 0.001) were associated with islet autoantibody positivity.ConclusionThe prevalence of islet autoantibody positivity was relatively low, suggesting that pancreatic autoimmunity is a rare cause of new-onset diabetes in this adult Ugandan population. Living in a rural area and being initiated on insulin therapy were independently associated with islet autoantibody positivity in this study population.
| S-EPMC9126391 | biostudies-literature
Project description:AimsOur aim was to synthesize current evidence on the association between parental smoking and incidence of type 1 diabetes and islet autoantibody positivity (IA) in the offspring by conducting a systematic review and meta-analysis.MethodsWe searched Medline, Embase, and Cochrane Library until January 21, 2021, for human studies with parental tobacco use as exposure, type 1 diabetes or IA as outcome, and hazard, risk, or odds ratios as effect estimates. Summary relative risks (RR) and 95% confidence intervals (CI) were estimated with random-effects models. Heterogeneity was quantified with the I2 statistic, bias with the ROBINS-I tool, and the certainty of evidence with the GRADE tool.ResultsWe identified 535 records of which 23 were eligible including 25 927 cases of type 1 diabetes. Maternal smoking during pregnancy was associated with a reduced risk of type 1 diabetes (n = 22, RR 0.78, CI 0.71-0.86, I2 =69%). Including only studies with low to moderate risk of bias indicated similar results with less heterogeneity (n = 14, RR 0.73, CI 0.68-0.79, I2 = 44%). The certainty of evidence was graded as high. There was no clear association between type 1 diabetes and neither maternal (n = 6, RR 0.95, CI 0.78-1.14, I2 = 0%) nor paternal (n = 6, RR 0.90, 0.70-1.17, I2 = 68%) smoking during childhood. Furthermore, the association between maternal smoking during pregnancy and IA was weak (n = 4, RR 0.86, CI 0.44-1.65, I2 = 71%).ConclusionsMaternal smoking during pregnancy may reduce the risk of type 1 diabetes in the offspring. Further studies are needed to elucidate potential mechanisms underlying this association.RegistrationProspero CRD42021236717.
| S-EPMC9311676 | biostudies-literature
Project description:Genetic variants affecting pancreatic islet enhancers are central to T2D risk, but the gene targets of islet enhancer activity are largely unknown. We generate a high-resolution map of islet chromatin loops using Hi-C assays in three islet samples and use loops to annotate target genes of islet enhancers defined using ATAC-seq and published ChIP-seq data. We identify candidate target genes for thousands of islet enhancers, and find that enhancer looping is correlated with islet-specific gene expression. We fine-map T2D risk variants affecting islet enhancers, and find that candidate target genes of these variants defined using chromatin looping and eQTL mapping are enriched in protein transport and secretion pathways. At IGF2BP2, a fine-mapped T2D variant reduces islet enhancer activity and IGF2BP2 expression, and conditional inactivation of IGF2BP2 in mouse islets impairs glucose-stimulated insulin secretion. Our findings provide a resource for studying islet enhancer function and identifying genes involved in T2D risk.
| S-EPMC6505525 | biostudies-literature
Project description:Aims:To examine the association between islet autoantibody positivity and clinical characteristics, residual β-cell function (C-peptide) and prevalence of complications in a childhood-onset (age <17 years), long-duration (≥32 years) type 1 diabetes cohort.Methods:Islet autoantibodies (glutamic acid decarboxylase, insulinoma-associated protein 2 and zinc transporter-8 antibodies) were measured in the serum of participants who attended the 2011-2013 Pittsburgh Epidemiology of Diabetes Complications study follow-up examination (n=177, mean age 51 years, diabetes duration 43 years).Results:Prevalences of islet autoantibodies were: glutamic acid decarboxylase, 32%; insulinoma-associated protein 2, 22%; and zinc transporter-8, 4%. Positivity for each islet autoantibody was associated with older age at diabetes onset (glutamic acid decarboxylase antibodies, P=0.03; insulinoma-associated protein 2 antibodies, P=0.001; zinc transporter-8 antibodies, P<0.0001). Older age at onset was also associated with an increasing number of autoantibodies (P = 0.001). Glutamic acid decarboxylase antibody positivity was also associated with lower HbA1c (P = 0.02), insulinoma-associated protein 2 antibody positivity was associated with lower prevalence of severe hypoglycaemic episodes (P=0.02) and both distal and autonomic neuropathy (P=0.04 for both), and zinc transporter-8 antibody positivity was associated with higher total and LDL cholesterol (P=0.01). No association between autoantibody positivity and C-peptide was observed.Conclusions:The strong association between islet autoantibody positivity and older age at type 1 diabetes onset supports the hypothesis of a less aggressive, and thus more persistent, immune process in those with older age at onset. This observation suggests that there may be long-term persistence of heterogeneity in the underlying autoimmune process.
| S-EPMC7369217 | biostudies-literature