1.
Andersen, Marie Louise M., et al.
(författare)
Association between autoantibodies to the Arginine variant of the Zinc transporter 8 (ZnT8) and stimulated C-peptide levels in Danish children and adolescents with newly diagnosed type 1 diabetes
2012
Ingår i: Pediatric Diabetes. - : Hindawi Limited. - 1399-543X .- 1399-5448. ; 13:6, s. 454-462
Tidskriftsartikel (refereegranskat) abstract
Background The zinc transporter 8 (ZnT8) was recently identified as a common autoantigen in type 1 diabetes (T1D) and inclusion of ZnT8 autoantibodies (ZnT8Ab) was found to increase the diagnostic specificity of T1D. Objectives The main aims were to determine whether ZnT8Ab vary during follow-up 1 year after diagnosis, and to relate the reactivity of three types of ZnT8Ab to the residual stimulated C-peptide levels during the first year after diagnosis. Subjects A total of 129 newly diagnosed T1D patients <15 years was followed prospectively 1, 3, 6, and 12 months after diagnosis. Methods Hemoglobin A1c, meal-stimulated C-peptide, ZnT8Ab, and other pancreatic autoantibodies were measured at each visit. Patients were genotyped for the rs13266634 variant at the SLC30A8 gene and HLA-DQ alleles. Results The levels of all ZnT8Ab [ZnT8Arg (arginine), ZnT8Trp (tryptophan), ZnT8Gln (glutamine)] tended to decrease during disease progression. A twofold higher level of ZnT8Arg and ZnT8Gln was associated with 4.6%/5.2% (p = 0.02), 5.3%/8.2% (p = 0.02) and 8.9%/9.7% (p = 0.004) higher concentrations of stimulated C-peptide 3, 6, and 12 months after diagnosis. The TT genotype carriers of the SLC30A8 gene had 45.8% (p = 0.01) and 60.1% (p = 0.002) lower stimulated C-peptide 6 and 12 months after diagnosis compared to the CC and the CT genotype carriers in a recessive model. Conclusions The levels of the Arg variant of the ZnT8 autoantibodies are associated with higher levels of stimulated C-peptide after diagnosis of T1D and during follow-up. Carriers of the TT genotype of the SLC30A8 gene predict lower stimulated C-peptide levels 12 months after diagnosis.
2.
Vaziri Sani, Fariba, et al.
(författare)
A novel triple mix radiobinding assay for the three ZnT8 (ZnT8-RWQ) autoantibody variants in children with newly diagnosed diabetes
2011
Ingår i: JIM - Journal of Immunological Methods. - : Elsevier. - 0022-1759 .- 1872-7905. ; 371:1-2, s. 25-37
Tidskriftsartikel (refereegranskat) abstract
Background and aims: Autoantibodies against the zinc transporter 8 (ZnT8A) are common in type 1 diabetes (T1D). ZnT8A analyses are complicated by the fact that there are three variants of the autoantigen at amino acid position 325 representing ZnT8-R (Arginine), ZnT8-W (Tryptophan) and ZnT8-Q (Glutamin). The aims of the study were: 1) to develop an autoantigen triple mix Radio-Binding Assay (RBA) for ZnT8A: 2) to identify the individual ZnT8-R,-W,-QA reactivity and 3) to validate the triple mix ZnT8A RBA in children with newly diagnosed T1D. less thanbrgreater than less thanbrgreater thanMethods: Serum samples were obtained from 2664 (56% males, n = 1436) patients in the Swedish nationwide Better Diabetes Diagnosis (BDD) study representing patients with T1D (97%, n = 2582), T2D (1.7%, n = 46), MODY (1.0%, n = 28) and secondary diabetes (0.3%, n = 8). cDNA coding for the C-terminal end of each variant was prepared by site-directed mutagenesis and subcloned into a high efficiency in vitro transcription translation vector. The ZnT8 variants were labeled with 35S-methionine and used in a standard RBA separating free from autoantibody-bound autoantigen with Protein A-Sepharose. less thanbrgreater than less thanbrgreater thanResults: ZnT8-TripleA was detected in 1678 (65%) patients with T1D, 4 (9%) T2D, 3 (11%) MODY and in none (0%) of the patients with secondary diabetes. Among the T1D patients ZnT8-RA was detected in 1351 (52%) patients, ZnT8-WA in 1209(47%) and ZnT8-QA in 790(31%) demonstrating that 1661 (64%) had one or several ZnT8A. The ZnT8-TripleA assay showed a false positive rate of 1.9% (n = 49). Only 1.2% (n = 32) of the T1D patients were false negative for ZnT8-TripleA compared to 0/46(0%) of the T2D patients. The precision (intra assay CV) and reproducibility (inter assay CV) of the ZnT8-TripleA assay did not differ from the RBA of the individual ZnT8 variants. less thanbrgreater than less thanbrgreater thanConclusion: We conclude that the ZnT8-TripleA assay had low false positive and false negative rates. The ZnT8-TripleA assay would therefore be highly suitable not only to analyze patient with newly diagnosed diabetes but also for screening the general population since this assay demonstrated high sensitivity and very high specificity.
3.
Agardh, Daniel, et al.
(författare)
Autoantibodies Against Soluble and Immobilized Human Recombinant Tissue Transglutaminase in Children with Celiac Disease.
2005
Ingår i: Journal of Pediatric Gastroenterology and Nutrition - Jpgn. - : Ovid Technologies (Wolters Kluwer Health). - 1536-4801 .- 0277-2116. ; 41:3, s. 322-327
Tidskriftsartikel (refereegranskat) abstract
Objectives: The conformation of tissue transglutaminase might influence the performance of immunoassays to detect autoantibodies from patients with celiac disease. The present study investigated how the exposure of tissue transglutaminase kept in a liquid phase and fixed to a solid support affected the binding of immunoglobulin (Ig)A and IgG autoantibodies in children with untreated and treated celiac disease. Methods: Included were 73 untreated celiac disease children, 50 controls and 80 children with treated celiac disease. IgA and IgG antitissue transglutaminase were measured with solid phase enzyme-linked immunoassay (ELISA) and liquid phase radioligand binding assays. For IgG antitissue transglutaminase detection with radioligand binding assays antihuman IgG and protein A were used. IgA endomysial autoantibodies were measured by indirect immunofluorescence. Results: Both ELISA and radioligand binding assays detected IgA antitissue transglutaminase in 65 of 73 untreated celiac disease children and in 2 of 50 controls. One additional control child was detected with radioligand binding assays. Endomysial autoantibodies were present in 62 of 73 celiac disease children and in 2 of 50 controls. IgG antitissue transglutaminase was detected with both ELISA and radioligand binding assays in 40 of 73 untreated celiac disease children and in 2 of 50 controls. Radioligand binding assays using protein A detected 20 of 73 additional untreated celiac disease children and one control child with increased IgG antitissue transglutaminase. In treated celiac disease children, 21 of 80 were IgA antitissue transglutaminase positive with radioligand binding assays, 3 of 80 with ELISA, whereas none had endomysial autoantibodies. Conclusions: No qualitative differences between radioligand binding assays and ELISA in IgA or IgG antitissue transglutaminase binding from untreated celiac disease children was demonstrated. However, discrepancies in the binding of IgA antitissue transglutaminase from a subgroup of treated celiac disease children indicated that alterations of tissue transglutaminase might occur on fixation of the antigen. Protein A used for radioligand binding assays seemed not to assess IgG autoantibodies exclusively. IgA antitissue transglutaminase detection in screening of childhood celiac disease can be performed either by ELISA or radioligand binding assays because the two assays are interchangeable.
4.
Andersson Svärd, Agnes, et al.
(författare)
Decreased HLA-DQ expression on peripheral blood cells in children with varying number of beta cell autoantibodies
2020
Ingår i: Journal of Translational Autoimmunity. - : Elsevier BV. - 2589-9090. ; 3
Tidskriftsartikel (refereegranskat) abstract
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.
5.
Falorni, Alberto, et al.
(författare)
Determination of 21-hydroxylase autoantibodies: inter-laboratory concordance in the Euradrenal International Serum Exchange Program
2015
Ingår i: Clinical Chemistry and Laboratory Medicine. - : Walter de Gruyter GmbH. - 1434-6621 .- 1437-4331. ; 53:11, s. 1761-1770
Tidskriftsartikel (refereegranskat) abstract
Background: 21-Hydroxylase autoantibodies (21OHAb) are markers of an adrenal autoimmune process that identifies individuals with autoimmune Addison's disease (AAD). Quality and inter-laboratory agreement of various 21OHAb tests are incompletely known. The objective of the study was to determine inter-laboratory concordance for 21OHAb determinations. Methods: Sixty-nine sera from 51 patients with AAD and 51 sera from 51 healthy subjects were blindly coded by a randomization center and distributed to 14 laboratories that determined 21OHAb, either by an "in-house" assay (n=9) using in vitro-translated S-35-21OH or luciferase-labeled 21OH or a commercial kit with I-125-21OH (n=5). Main outcome measures were diagnostic accuracy of each participating laboratory and inter-laboratory agreement of 21OHAb assays. Results: Intra-assay coefficient of variation ranged from 2.6% to 5.3% for laboratories using the commercial kit and from 5.1% to 23% for laboratories using "in-house" assays. Diagnostic accuracy, expressed as area under ROC curve (AUC), varied from 0.625 to 0.947 with the commercial kit and from 0.562 to 0.978 with "in-house" methods. Cohen's. of inter-rater agreement was 0.603 among all 14 laboratories, 0.691 among "in-house" laboratories, and 0.502 among commercial kit users. Optimized cutoff levels, calculated on the basis of AUCs, increased the diagnostic accuracy of every laboratory (AUC >0.9 for 11/14 laboratories) and increased the Cohen's. of inter-rater agreement. Discrepancies in quantitation of 21OHAb levels among different laboratories increased with increasing autoantibody levels. Conclusions: The quality of 21OHAb analytical procedures is mainly influenced by selection of cutoff value and correct handling of assay materials. A standardization program is needed to identify common standard sera and common measuring units.
6.
Gebe, John A, et al.
(författare)
Age-dependent loss of tolerance to an immunodominant epitope of glutamic acid decarboxylase in diabetic-prone RIP-B7/DR4 mice.
2006
Ingår i: Clinical Immunology. - : Elsevier BV. - 1521-6616. ; 121:3, s. 294-304
Tidskriftsartikel (refereegranskat) abstract
We have identified for the first time an age-dependent spontaneous loss of tolerance to two self-antigenic epitopes derived from putative diabetes-associated antigens glutamic acid decarboxylase (GAD65) and glial fibrillary acidic protein (GFAP) in RIP-B7/DRB1*0404 HLA transgenic mice. Diabetic and older non-diabetic mice exhibited a proliferative response to an immunodominant epitope from GAD65 (555-567) and also from GFAP (240-252) but not from an immunogenic epitope from diabetes-associated islet-specific glucose-6-phosphatase catalytic subunit-related protein. The response to both of these self-antigens is not observed in young mice but is observed in older non-diabetic mice and is accompanied by histological evidence of insulitis in the absence of overt diabetes. Islet infiltrates in older non-diabetic mice and diabetic mice contain CD4(+)/FoxP3(+) cells and suggest the presence of a regulatory mechanism prior and during diabetic disease. Diabetes penetrance in RIP-B7/DR0404 mice
7.
Gu, Gucci Jijuan, et al.
(författare)
Elevated Serum GAD65 and GAD65-GADA Immune Complexes in Stiff Person Syndrome.
2015
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
Tidskriftsartikel (refereegranskat) abstract
Glutamic acid decarboxylase 65 (GAD65) and autoantibodies specific for GAD65 (GADA) are associated with autoimmune diseases including Stiff Person Syndrome (SPS) and Type 1 diabetes (T1D). GADA is recognized as a biomarker of value for clinical diagnosis and prognostication in these diseases. Nonetheless, it remains medically interesting to develop sensitive and specific assays to detect GAD65 preceding GADA emergence, and to monitor GADA-GAD65 immune complexes in blood samples. In the present study, we developed a highly sensitive proximity ligation assay to measure serum GAD65. This novel assay allowed detection of as little as 0.65 pg/ml GAD65. We were also able to detect immune complexes involving GAD65 and GADA. Both free GAD65 and GAD65-GADA levels were significantly higher in serum samples from SPS patients compared to healthy controls. The proximity ligation assays applied for detection of GAD65 and its immune complexes may thus enable improved diagnosis and better understanding of SPS.
8.
Gupta, Manu, et al.
(författare)
Association between the transmembrane region polymorphism of MHC class I chain related gene-A and type 1 diabetes mellitus in Sweden
2003
Ingår i: Human Immunology. - 0198-8859. ; 64:5, s. 553-561
Tidskriftsartikel (refereegranskat) abstract
Major histocompatibility complex (MHC) class I chain related gene-A (MIC-A) is associated with type 1 diabetes mellitus (T1DM) in other populations. We tested the association of MIC-A gene polymorphism with T1DM in Swedish Caucasians; if it has an age-dependent association; and if the association has an effect on gender. We studied 635 T1DM patients and 503 matched controls in the age group of 0-35 years old. MIC-A5 was significantly increased in T1DM compared with controls (odds ratio [OR] =1.81, p(c) < 0.0005). Logistic regression analysis revealed MIC-A5 association was independent of HLA. MIC-A5 with DR4-DQ8 or MIC-A5 with DR3-DQ2 gave higher OR than the OR obtained with either of them alone (OR = 1.81, 7.1, and 3.6, respectively). MIC-A5 was positively (OR = 2.48, p(c) < 0.0005) and MIC-A6 negatively associated (OR = 0.61, p(c) = 0.035) with the disease in less than or equal to 20 years of age. The negative association of MIC-A6 in young onset was confirmed by logistic regression analysis. MIC-A5 was associated with the disease in males (OR = 2.05, p(c) = 0.0005). MIC-A6 conferred protection (OR = 0.098, p(c) = 0.032) in females heterozygous for DR3/DR4. In conclusion, MIC-A5 is associated with T1DM; the association was higher in individuals less than or equal to 20 years old; and negative association of MIC-A6 was stronger in younger onset patients than in older onset patients.
9.
Hirai, Hiroki, et al.
(författare)
Selective screening of secretory vesicle-associated proteins for autoantigens in type 1 diabetes: VAMP2 and NPY are new minor autoantigens
2008
Ingår i: Clinical Immunology. - : Elsevier BV. - 1521-6616. ; 127:3, s. 366-374
Tidskriftsartikel (refereegranskat) abstract
The four major autoantigens (IA-2, IA-2 beta, GAD65 and insulin) of type 1 diabetes are all associated with dense core or synaptic vesicles. This raised the possibility that other secretory vesicle-associated proteins might be targets of the autoimmune response in type 1 diabetes. To test this hypothesis 56 proteins, two-thirds of which are associated with secretory vesicles, were prepared by in vitro transcription/translation and screened for autoantibodies by liquid phase radioimmunoprecipitation. Two secretory vesicle-associated proteins, VAMP2 and NPY, were identified as new minor autoantigens with 21% and 9%, respectively, of 200 type 1 diabetes sera reacting positively. These findings add support to the hypothesis that secretory vesicle-associated proteins are particularly important, but not the exclusive, targets of the autoimmune response in type 1 diabetes. Selective screening of the human proteome offers a useful approach for identifying new autoantigens in autoimmune diseases.
10.
La Torre, Daria, et al.
(författare)
Decreased cord-blood phospholipids in young age-at-onset type 1 diabetes
2013
Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 62:11, s. 3951-3956
Tidskriftsartikel (refereegranskat) abstract
Children developing type 1 diabetes may have risk markers already in their umbilical cord blood. It is hypothesized that the risk for type 1 diabetes at an early age may be increased by a pathogenic pregnancy and be reflected in altered cord-blood composition. This study used metabolomics to test if the cord-blood lipidome was affected in children diagnosed with type 1 diabetes before 8 years of age. The present case-control study of 76 index children diagnosed with type 1 diabetes before 8 years of age and 76 healthy control subjects matched for HLA risk, sex, and date of birth, as well as the mother's age and gestational age, revealed that cord-blood phosphatidylcholines and phosphatidylethanolamines were significantly decreased in children diagnosed with type 1 diabetes before 4 years of age. Reduced levels of triglycerides correlated to gestational age in index and control children and to age at diagnosis only in the index children. Finally, gestational infection during the first trimester was associated with lower cord-blood total lysophosphatidylcholines in index and control children. In conclusion, metabolomics of umbilical cord blood may identify children at increased risk for type 1 diabetes. Low phospholipid levels at birth may represent key mediators of the immune system and contribute to early induction of islet autoimmunity.
