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Kawasaki E, Jinnouchi H, Maeda Y, Okada A, Kawai K. Estimation of Individual Positive Anti-Islet Autoantibodies from 3 Screen ICA Titer. Int J Mol Sci 2024; 25:7618. [PMID: 39062856 PMCID: PMC11277171 DOI: 10.3390/ijms25147618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2024] [Revised: 07/07/2024] [Accepted: 07/08/2024] [Indexed: 07/28/2024] Open
Abstract
The 3 Screen ICA ELISA is a novel assay capable of simultaneously measuring autoantibodies to glutamic acid decarboxylase (GADA), insulinoma-associated antigen-2 (IA-2A), and zinc transporter 8 (ZnT8A), making it a valuable tool for screening type 1 diabetes. Despite its advantages, it cannot specify which individual autoantibodies are positive or negative. This study aimed to estimate individual positive autoantibodies based on the 3 Screen ICA titer. Six hundred seventeen patients with type 1 diabetes, simultaneously measured for 3 Screen ICA and three individual autoantibodies, were divided into five groups based on their 3 Screen ICA titer. The sensitivities and contribution rates of the individual autoantibodies were then examined. The study had a cross-sectional design. Sixty-nine percent (424 of 617) of patients with type 1 diabetes had 3 Screen ICA titers exceeding the 99th percentile cut-off level (20 index). The prevalence of GADA ranged from 80% to 100% in patients with a 3 Screen ICA over 30 index and 97% of patients with a 3 Screen ICA ≥300 index. Furthermore, the prevalence of all individual autoantibodies being positive was 0% for ≤80 index and as high as 92% for ≥300 index. Significant associations were observed in specific titer groups: the 20-29.9 index group when all the individual autoantibodies were negative, the 30-79.9 index group when positive for GADA alone or IA-2A alone, the 30-299.9 index group when positive for ZnT8A alone, the 80-299.9 index group when positive for both IA-2A and ZnT8A, the 300-499.9 index group when positive for both GADA and ZnT8A, and the ≥300 index group when positive for all individual autoantibodies. These results suggest that the 3 Screen ICA titer may be helpful in estimating individual positive autoantibodies.
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Affiliation(s)
- Eiji Kawasaki
- Diabetes, Thyroid, and Endocrine Center, Shin-Koga Hospital, Kurume 830-8577, Japan
| | - Hideaki Jinnouchi
- Department of Internal Medicine, Jinnouchi Hospital Diabetes Care Center, Kumamoto 862-0976, Japan;
| | - Yasutaka Maeda
- Minami Diabetes Clinical Research Center, Clinic Masae Minami, Fukuoka 815-0071, Japan;
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Kawasaki E. Anti-Islet Autoantibodies in Type 1 Diabetes. Int J Mol Sci 2023; 24:10012. [PMID: 37373160 PMCID: PMC10298549 DOI: 10.3390/ijms241210012] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/08/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Anti-islet autoantibodies serve as key markers in immune-mediated type 1 diabetes (T1D) and slowly progressive T1D (SPIDDM), also known as latent autoimmune diabetes in adults (LADA). Autoantibodies to insulin (IAA), glutamic acid decarboxylase (GADA), tyrosine phosphatase-like protein IA-2 (IA-2A), and zinc transporter 8 (ZnT8A) are currently employed in the diagnosis, pathological analysis, and prediction of T1D. GADA can also be detected in non-diabetic patients with autoimmune diseases other than T1D and may not necessarily reflect insulitis. Conversely, IA-2A and ZnT8A serve as surrogate markers of pancreatic β-cell destruction. A combinatorial analysis of these four anti-islet autoantibodies demonstrated that 93-96% of acute-onset T1D and SPIDDM cases were diagnosed as immune-mediated T1D, while the majority of fulminant T1D cases were autoantibody-negative. Evaluating the epitopes and immunoglobulin subclasses of anti-islet autoantibodies help distinguish between diabetes-associated and non-diabetes-associated autoantibodies and is valuable for predicting future insulin deficiency in SPIDDM (LADA) patients. Additionally, GADA in T1D patients with autoimmune thyroid disease reveals the polyclonal expansion of autoantibody epitopes and immunoglobulin subclasses. Recent advancements in anti-islet autoantibody assays include nonradioactive fluid-phase assays and the simultaneous determination of multiple biochemically defined autoantibodies. Developing a high-throughput assay for detecting epitope-specific or immunoglobulin isotype-specific autoantibodies will facilitate a more accurate diagnosis and prediction of autoimmune disorders. The aim of this review is to summarize what is known about the clinical significance of anti-islet autoantibodies in the pathogenesis and diagnosis of T1D.
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Affiliation(s)
- Eiji Kawasaki
- Diabetes Center, Shin-Koga Hospital, Kurume 830-8577, Japan
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Wen S, Jiang W, Zhou L. Islet Autoantibodies in the Patients with Sjogren's Syndrome and Thyroid Disease and Risk of Progression to Latent Autoimmune Diabetes in Adults: A Case Series. Diabetes Metab Syndr Obes 2021; 14:1025-1033. [PMID: 33707961 PMCID: PMC7943329 DOI: 10.2147/dmso.s295847] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 02/22/2021] [Indexed: 12/17/2022] Open
Abstract
The glutamic acid decarboxylase 65 antibody (GAD65-Ab) is an autoimmune marker in some diseases such as diabetes or autoimmune disorders of the central nervous system such as stiff-man syndrome. It can appear with other pancreatic autoantibodies, such as insulin autoantibodies (IAA), presenting as early signs of pancreatic islet β-cells impairing, and play roles in the pathogenesis of type1 diabetes (T1D) and latent autoimmune diabetes in adults (LADA). Positive GAD65-Ab is rarely observed in insulin-dependent diabetic patients with other acquired autoimmune diseases, such as Sjogren's syndrome (SS). Besides, LADA revealed by islet autoantibodies such as GAD65-Ab can also be complicated with Hashimoto's thyroiditis (HT), another autoimmune thyroid disease. To date, whether GAD65-Ab positive in patients with autoimmune diseases predicts the onset or progression to T1D or LADA remains unknown. Herein, two unique cases of middle-aged Chinese Han women free from diabetes for three years are described despite their blood tests persistently testing positive for GAD65-Ab or IAA. Both patients suffered from HT and SS. Follow-up OGTTs (oral glucose tolerance test) for three years revealed that the patients had a well-controlled glycemic level and normal pancreatic function. However, one of the patients had a temporary increase of postprandial glucose after a short-term loss of diet control. The presence of auto-immune antibodies in these patients had little impact on glucose tolerance or insulin secretion in 3 years. The study postulate that both the primary immune injury caused by serum GAD65-Ab positive, an autoimmune marker, and increased body weight contribute to the progression of LADA.
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Affiliation(s)
- Song Wen
- Department of Endocrinology, Shanghai Pudong Hospital, Fudan University, Shanghai, 201399, People’s Republic of China
| | - Wenjing Jiang
- Department of Endocrinology, Shanghai Pudong Hospital, Fudan University, Shanghai, 201399, People’s Republic of China
| | - Ligang Zhou
- Department of Endocrinology, Shanghai Pudong Hospital, Fudan University, Shanghai, 201399, People’s Republic of China
- Correspondence: Ligang Zhou Department of Endocrinology, Shanghai Pudong Hospital, Fudan University, Shanghai, 201399, People’s Republic of ChinaTel +8613611927616 Email
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Morgan NG, Leete P, Foulis AK, Richardson SJ. Islet inflammation in human type 1 diabetes mellitus. IUBMB Life 2014; 66:723-34. [PMID: 25504835 DOI: 10.1002/iub.1330] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 11/17/2014] [Indexed: 01/12/2023]
Abstract
Type 1 diabetes mellitus (T1DM) is caused by the selective deletion of pancreatic β-cells in response to an assault mounted within the pancreas by infiltrating immune cells. However, this apparently clear and focussed annunciation conceals a stark reality in which the cellular and molecular events leading to β-cell loss remain poorly understood in humans. This reflects the difficulty of studying these processes in living individuals and the fact that, using pathological specimens, islet inflammation has been analysed in fewer than 200 recent-onset cases of T1DM worldwide, over the past century. Nevertheless, insights have been gained and the composition of the islet infiltrate is being disclosed. This is shown to be primarily lymphocytic in nature, with populations of both CD8+ and CD4+ T cells displaying an autoreactivity against specific islet antigenic peptides. The T cells are often accompanied by influent CD20+ B cells, although new data imply that the proportions of these individual cell types vary and that patients fall into at least two distinct categories having either a hyper-immune (CD20Hi) or a pauci-immune (CD20Lo) phenotype. The overall rate of β-cell decline appears to correlate with these two phenotypes such that hyper-immune patients lose β-cells more quickly and tend to develop disease at an earlier age than those with the pauci-immune profile. In this article, we review the evidence which underpins our current understanding of the aetiology of T1DM and highlight both the established features as well as areas of on-going ambiguity and debate.
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Affiliation(s)
- Noel G Morgan
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, UK
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Purification of pituitary autoantigen by column liquid chromatography and chromatofocusing. Cent Eur J Immunol 2014; 39:46-50. [PMID: 26155099 PMCID: PMC4439984 DOI: 10.5114/ceji.2014.42122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 11/28/2013] [Indexed: 11/29/2022] Open
Abstract
Introduction Pituitary autoantibodies can be determined both in patients with pituitary disease as well as patients with autoimmune endocrine diseases. The purpose of the study was to isolate and purify pituitary autoantigen using sera of patients and the microsomal fraction of the pituitary. Material and methods To isolate a pituitary autoantigen, patient sera were used, which showed a strong immune response to pituitary antigens. Pituitary microsomal fractions were prepared from pituitary tissue homogenates. In the study, sera of patients with pituitary disease, Addison and Graves’ disease were used. The initial stages were carried out by affinity chromatography on CN -Br sepharose column whereas purification was continued by column liquid chromatography on AcA54 Ultrogel. Chromatofocusing was performed by Polybuffer exchanger PBE 94. Results 125I-labeled pituitary antigens after isolation appeared in column chromatography in three peaks. The first peak contained 50-70 kDa proteins, the second peak – 17 to 22 kDa proteins and the third peak contains 125-iodides. Three fractions obtained from filtration on Ultrogel were separated in a polyacrylamide gel. In the first peak two bands 67 and 55 kDa appeared. The second peak contained low molecular weight substances, and the third peak contained 125I. The first peak from Ultrogel was isolated by chromatofocusing – the first peak with pH 5.9 and the second one with pH 4.9. Conclusions Isolation and purification of pituitary autoantigen with the use of column liquid chromatography and chromatofocusing resulted in obtainment of two antigenic proteins of specific gravity of 67 and 55 kDa.
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Kawasaki E, Yasui JI, Tsurumaru M, Takashima H, Ikeoka T, Mori F, Akazawa S, Ueki I, Kobayashi M, Kuwahara H, Abiru N, Yamasaki H, Kawakami A. Sequential elevation of autoantibodies to thyroglobulin and glutamic acid decarboxylase in type 1 diabetes. World J Diabetes 2013; 4:227-230. [PMID: 24147207 PMCID: PMC3797888 DOI: 10.4239/wjd.v4.i5.227] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 07/25/2013] [Accepted: 08/16/2013] [Indexed: 02/05/2023] Open
Abstract
We have previously reported the high levels of glutamic acid decarboxylase 65 autoantibodies (GAD65A) in patients with type 1 diabetes and autoimmune thyroid disease. Here we describe a 32-year-old Japanese female with a thirteen-year history of type 1 diabetes whose levels of GAD65A were elevated just after the emergence of anti-thyroid autoimmunity. At 19 years of age, she developed diabetic ketoacidosis and was diagnosed with type 1 diabetes. She had GAD65A, insulinoma-associated antigen-2 autoantibodies (IA-2A), and zinc transporter-8 autoantibodies (ZnT8A), but was negative for antibodies to thyroid peroxidase (TPOAb) and thyroglobulin (TGAb) at disease onset. ZnT8A and IA-2A turned negative 2-3 years after the onset, whereas GAD65A were persistently positive at lower level (approximately 40 U/mL). However, just after the emergence of TGAb at disease duration of 12.5 years, GAD65A levels were reelevated up to 5717 U/mL in the absence of ZnT8A and IA-2A. Her thyroid function was normal and TPOAb were consistently negative. She has a HLA-DRB1*03:01/*04:01-DQB1*02:01/*03:02 genotype. Persistent positivity for GAD65A might be associated with increased risk to develop anti-thyroid autoimmunity.
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Wägner AM, Santana Á, Hernández M, Wiebe JC, Nóvoa J, Mauricio D. Predictors of associated autoimmune diseases in families with type 1 diabetes: results from the Type 1 Diabetes Genetics Consortium. Diabetes Metab Res Rev 2011; 27:493-8. [PMID: 21744463 PMCID: PMC3137249 DOI: 10.1002/dmrr.1189] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
BACKGROUND Type 1 diabetes (T1D) is a clinically heterogeneous disease. The presence of associated autoimmune diseases (AAIDs) may represent a distinct form of autoimmune diabetes, with involvement of specific mechanisms. The aim of this study was to find predictors of AAIDs in the Type 1 Diabetes Genetics Consortium data set. METHODS Three thousand two hundred and sixty-three families with at least two siblings with T1D were included. Clinical information was obtained using questionnaires, anti-GAD (glutamic acid decarboxylase) and anti-protein tyrosine phosphatase (IA-2) were measured and human leukocyte antigen (HLA) genotyping was performed. Siblings with T1D with and without AAIDs were compared and a multivariate regression analysis was performed to find predictors of AAIDs. T1D-associated HLA haplotypes were defined as the four most susceptible and protective, respectively. RESULTS One or more AAIDs were present in 14.4% of the T1D affected siblings. Age of diabetes onset, current age and time since diagnosis were higher, there was a female predominance and more family history of AAIDs in the group with AAIDs, as well as more frequent anti-GAD and less frequent anti-IA-2 antibodies. Risk and protective HLA haplotype distributions were similar, though DRB1*0301-DQA1*0501-DQB1*0201 was more frequent in the group with AAIDs. In the multivariate analysis, female gender, age of onset, family history of AAID, time since diagnosis and anti-GAD positivity were significantly associated with AAIDs. CONCLUSIONS In patients with T1D, the presence of AAIDs is associated with female predominance, more frequent family history of AAIDs, later onset of T1D and more anti-GAD antibodies, despite longer duration of the disease. The predominance of certain HLA haplotypes suggests that specific mechanisms of disease may be involved.
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Affiliation(s)
- Ana M Wägner
- Endocrinology Dept. Complejo Hospitalario Universitario Insular-Materno Infantil de Gran Canaria, Spain
- Departamento de Ciencias Medicas y Quirurgicas. Universidad de Las Palmas de Gran Canaria
- Corresponding author and reprint requests: Endocrinology Dept. Complejo Hospitalario Universitario Insular-Materno Infantil. Av Marítima del sur s/n. 35016 Las Palmas de Gran Canaria. Spain. Telephone: +34 928 441937 (direct) / 1617 (sec) Fax: +34 928 441586
| | - Ángelo Santana
- Departamento de Matematicas y Estadistica. Universidad de Las Palmas de Gran Canaria
| | - Marta Hernández
- Endocrinology Dept. Hospital Universitari Arnau de Vilanova, Lleida, Spain
| | - Julia C Wiebe
- Endocrinology Dept. Complejo Hospitalario Universitario Insular-Materno Infantil de Gran Canaria, Spain
| | - Javier Nóvoa
- Endocrinology Dept. Complejo Hospitalario Universitario Insular-Materno Infantil de Gran Canaria, Spain
- Departamento de Ciencias Medicas y Quirurgicas. Universidad de Las Palmas de Gran Canaria
| | - Didac Mauricio
- Endocrinology Dept. Hospital Universitari Arnau de Vilanova, Lleida, Spain
- Institut de Recerca Biomedica de Lleida
- Corresponding author 2: Endocrinology Dept. Hospital Universitari Arnau de Vilanova. Lleida, Spain
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Csorba TR, Lyon AW, Hollenberg MD. Autoimmunity and the pathogenesis of type 1 diabetes. Crit Rev Clin Lab Sci 2010; 47:51-71. [DOI: 10.3109/10408361003787171] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Schiel R, Müller UA. GAD autoantibodies in a selection-free population of insulin-treated diabetic patients: indicator of a high prevalence of LADA? Diabetes Res Clin Pract 2000; 49:33-40. [PMID: 10808061 DOI: 10.1016/s0168-8227(00)00139-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
UNLABELLED Up to the present only few data have been available concerning the prevalence of diabetes-specific autoantibodies (anti-GAD, ICA, IAA, IA-2) in unselected populations, in particular in type 2 diabetic patients. Hence, the aim of the present study was to determine the prevalence of anti-GAD in a selection-free population of insulin-treated diabetic patients. Accordingly, 90% of all the insulin-treated diabetic patients (type 1, n=127, type 2, n=117) aged 16-60 years and living in the city of Jena (100242 inhabitants) were examined. In order to test sera for anti-GAD, serum samples were taken in 75% of type 1 (n=95) and in 80% of insulin-treated type 2 diabetic (n=94) patients. RESULTS In the group of type 1 diabetic patients 55% of the patients tested were positive for anti-GAD. But, interestingly, in the type 2 group, a total of 21% patients were positive. With respect to this high percentage of anti-GAD positive type 2 diabetic patients it must be suggested that the frequency of patients with latent autoimmune diabetes mellitus in adults (LADA) was underestimated in the past.
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Affiliation(s)
- R Schiel
- Department of Internal Medicine II, University of Jena Medical School, D-07740, Jena, Germany.
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Taniyama H, Oka S, Yokota H, Hirayama K, Kagawa Y, Kurosawa T, Furuoka H, Ono T. Immunohistochemical detection of the enzyme glutamic acid decarboxylase and hormones of the islets of Langerhans in spontaneous insulin-dependent diabetes mellitus in cattle. Vet Pathol 1999; 36:628-31. [PMID: 10568450 DOI: 10.1354/vp.36-6-628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Immunohistochemical expression of glutamic acid decarboxylase (GAD) enzyme was detected in the pancreatic islets of 12 cattle with spontaneous insulin-dependent diabetes mellitus (IDDM). The most characteristic changes were atrophy and decreased number of pancreatic islets, enlarged islets with vacuolated beta cells, and lymphocytic islet adenitis. Atrophied islets were composed of small islet cells without cytoplasmic insulin-positive granules. Immunohistochemically, GAD was not found in the cytoplasm of atrophied islet cells. Furthermore, enlarged islets consisting of islet cells with vacuolated cytoplasm were frequently observed. The cytoplasm of vacuolated cells contained very few GAD- and insulin-positive granules, indicating beta cell destruction. Enlarged islets with mild lymphocytic infiltrates were frequently observed. These findings suggest that islet cells in cattle with IDDM lose their insulin synthesis function and their ability to regulate hormonal secretion of alpha and delta cells.
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Affiliation(s)
- H Taniyama
- Department of Veterinary Pathology, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan
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Tiberti C, Falorni A, Torresi P, Vecci E, Anastasi E, Dotta F, Di Mario U. A new solid-phase radioimmunoassay to detect anti-GAD65 autoantibodies. J Immunol Methods 1997; 207:107-13. [PMID: 9368637 DOI: 10.1016/s0022-1759(97)00101-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This paper describes a simple, rapid, routine method to detect anti-GAD65 autoantibodies by a solid-phase radioimmunoassay using human recombinant GAD65 coated microwells and 125I-protein A to reveal antibody binding. Both recombinant and radiolabelled proteins are commercially available. This new method was validated by investigating the presence of GAD65 autoantibodies in two different studies (A and B); the first including subjects originating from our own case histories (group A sera), the second made up of recoded subjects and standards sent to our lab by the Second International GAD Antibody Workshop organizers (group B sera). In study A we tested sera from 52 normal subjects, 25 newly diagnosed type 1 diabetics and 3 stiff man syndrome (SMS) subjects detecting GAD65 autoantibodies in 72% of IDDM and 100% of SMS patients. In study B we tested (in blind fashion) 89 recoded sample sera or standards that were part of the larger group used in the Second International GAD Antibody Workshop, finding GAD65 autoantibodies in 3.3% of healthy control subjects (1/30), 60% of IDDM patients (18/30), 100% of ICA + nondiabetic subjects (3/3) but in none of 4 nondiabetic patients with Graves disease. Comparing our solid-phase RIA results with those published for the same sera from the Second International GAD Antibody Workshop we obtained for our method a sensitivity of 85.7%, a specificity of 93.9% and a consistency of 100%. These result indicate that our assay, which is based on commercially available reagents, should be a useful tool for the detection of GAD65 autoantibodies in large scale studies.
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Affiliation(s)
- C Tiberti
- Department of Endocrinology, La Sapienza University, Rome, Italy
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Williamson S, Faulkner-Jones BE, Cram DS, Furness JB, Harrison LC. Transcription and translation of two glutamate decarboxylase genes in the ileum of rat, mouse and guinea pig. JOURNAL OF THE AUTONOMIC NERVOUS SYSTEM 1995; 55:18-28. [PMID: 8690847 DOI: 10.1016/0165-1838(95)00028-v] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
gamma-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter, synthesised from glutamate by glutamate decarboxylase (GAD), in the central nervous system. Two forms of GAD, designated GAD 65 and GAD 67, are encoded by distinct genes and have been demonstrated in the mammalian brain. GABA has been postulated to be synthesised in neurons of the enteric nervous system (ENS), but evidence for its role as an enteric neurotransmitter is equivocal. We therefore aimed to determine whether GAD 65 and GAD 67 messenger RNAs (mRNAs) and proteins were expressed in the ileum of mice, rats and guinea pigs. Using an RNase protection assay, both GAD 65 and GAD 67 mRNAs were detected in the rodent small intestine. Antisera specific for GAD 65 or GAD 67, used in immunoblot analyses, revealed GAD 65-like and GAD 67-like immunoreactivity in rat and guinea pig ileum. Anti-GAD 65 antisera detected a major band of 65 kDa. Anti-GAD 67 antisera detected a major band of 55 kDa, which probably represented a breakdown product, and a minor band of 67 kDa. Analysis of immunoblot extracts of rat and guinea pig ileum revealed more GAD 67-like than GAD 65-like immunoreactivity. GAD enzymatic activity was high in the rat and guinea-pig brain, and low in the whole and dissected ileum. These results demonstrate that both GAD 65 and GAD 67 genes are transcribed and translated in the ileum of three rodent species and lend indirect support to the postulate that GABA is synthesised by neurons of the ENS and intestinal endocrine cells.
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Affiliation(s)
- S Williamson
- Department of Anatomy and Cell Biology, University of Melbourne, Victoria, Australia
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Payton MA, Hawkes CJ, Christie MR. Relationship of the 37,000- and 40,000-M(r) tryptic fragments of islet antigens in insulin-dependent diabetes to the protein tyrosine phosphatase-like molecule IA-2 (ICA512). J Clin Invest 1995; 96:1506-11. [PMID: 7657822 PMCID: PMC185775 DOI: 10.1172/jci118188] [Citation(s) in RCA: 175] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Sera from patients with insulin-dependent diabetes immunoprecipitate 64,000-M(r) proteins, distinct from glutamate decarboxylase, that are cleaved to 37,000- and 40,000-M(r) fragments by trypsin. We investigated possible relationships between 37,000- or 40,000-M(r) fragments of antigen and the tyrosine phosphatase-like protein, IA-2 (ICA512). Antibodies from nondiabetic relatives bound differentially to 37,000- and 40,000-M(r) fragments indicating presence of distinct epitopes. Precursors of these fragments could be separated on immobilized lectins, suggesting different carbohydrate content. Levels of antibodies to 40,000-M(r) fragments were strongly associated with those to the intracellular domain of IA-2. Recombinant intracellular domain of IA-2 blocked binding of antibodies to 40,000-M(r) fragments expressed by insulinoma cells and partially blocked binding to 37,000-M(r) fragments. Furthermore, trypsinization of recombinant intracellular domain of IA-2 generated proteolytic fragments of identical M(r) to the 40,000-M(r) fragments of insulinoma antigen; 37,000-M(r) fragments were not generated. Thus, 40,000-M(r) fragments of islet autoantigen are derived from a protein similar or identical to the tyrosine phosphatase-like molecule, IA-2. The 37,000-M(r) fragments are derived from a different, although related, protein.
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Affiliation(s)
- M A Payton
- Department of Medicine, King's College School of Medicine and Dentistry, London, United Kingdom
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Beales PE, Hawa M, Williams AJ, Albertini MC, Giorgini A, Pozzilli P. Baclofen, a gamma-aminobutyric acid-b receptor agonist, delays diabetes onset in the non-obese diabetic mouse. Acta Diabetol 1995; 32:53-6. [PMID: 7612919 DOI: 10.1007/bf00581047] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Glutamic acid decarboxylase (GAD) is the enzyme responsible for the synthesis of gamma-aminobutyric acid (GABA). GAD has been identified as a 64-kDa antigen expressed in pancreatic beta-cells, to which autoantibodies are generated prior to the onset of type 1 (insulin-dependent) diabetes mellitus. GAD may therefore be an initiating factor in beta-cell destruction. We administered baclofen, a GABA-B receptor agonist, to non-obese diabetic (NOD) mice in an attempt to down-regulate GAD expression and thereby reduce the incidence of diabetes. Twenty-four female NOD mice were given baclofen in their drinking water at a final dose of 50 mg/kg body weight daily from weaning to 30 weeks of age. Twenty-four sex- and litter-matched mice were used as controls. At 30 weeks there was no difference in the incidence of diabetes in the treated group compared with the controls. However, there was a significant delay in the onset of diabetes in the treated group (P < 0.001, parallelism test). The degree of insulitis and the GAD activity in the pancreas per mg of protein were unchanged by baclofen treatment with respect to controls. These results suggest that baclofen may be effective in delaying diabetes onset in NOD mice by stimulating GABA activity, as this neurotransmitter, localised in the islets, may modulate insulin secretion and the antigen expression associated with it.
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Affiliation(s)
- P E Beales
- Department of Diabetes and Metabolism, St. Bartholomew's Hospital, London, UK
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Roll U, Scheeser J, Standl E, Ziegler AG. Alterations of lymphocyte subsets in children of diabetic mothers. Diabetologia 1994; 37:1132-41. [PMID: 7867885 DOI: 10.1007/bf00418377] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
To investigate the impact of diabetic mothers on the maturation of the immune system in their offspring, immunophenotypic markers of major lymphocyte subpopulations were evaluated by two-colour flow cytometric analysis in 160 healthy children of diabetic mothers (100 with insulin-dependent diabetes mellitus (IDDM): 48 with gestational diabetes), including 22 neonates, 45 infants aged 8-12 months, 46 children aged 1-2 years, 29 children aged 3-6 years and 18 children aged 7-17 years. Results were compared with 21 neonates of healthy mothers from our hospital and with 110 paediatric subjects of a reference population. In neonates of diabetic mothers, percentages of total lymphocytes (p = 0.044), T and B lymphocytes (p = 0.004, respectively) were significantly decreased compared to our neonates of healthy mothers. By subdividing the group of neonates in offspring of mothers with IDDM (n = 15) or gestational diabetes (n = 7), differences compared to normal neonates were mainly observed in neonates of mothers with IDDM (T lymphocytes: p = 0.006; B lymphocytes: p = 0.008). In cord blood, 45.5% of neonates had antibodies to islet cells, insulin or glutamic acid decarboxylase, most likely transmitted through the placenta of the diabetic mother. No association was found between alterations of lymphocyte subsets and antibody-positivity in cord blood, nor was there any correlation of lymphocyte counts and mean HbA1 during pregnancy, maternal age at delivery, diabetes duration, or neonatal birth weight, respectively. Comparisons among age groups from newborn infants through adolescents revealed higher percentages of total lymphocytes and lower percentages of activated T cells in children of diabetic mothers compared to children of the reference population between the age of 1 to 6 years (67-73% of the cases above and 62-77% below the interquartiles of the reference range, respectively). No significant differences in lymphocyte subpopulations between children of mothers with IDDM diabetes and gestational diabetes have been detected. In addition, there were no abnormalities of lymphocyte subsets in children who are at high risk for the development of IDDM. In summary, we suggest that the observed changes in children of diabetic mothers may reflect a cellular immune reaction to the particular maternal environment, characterized by both an abnormal metabolic state and persisting autoimmunity in the affected mother.
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Affiliation(s)
- U Roll
- Diabetes Research Institute, City Hospital Schwabing, Munich, Germany
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16
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Velloso LA, Björk E, Ballagi AE, Funa K, Andersson A, Kämpe O, Karlsson FA, Eizirik DL. Regulation of GAD expression in islets of Langerhans occurs both at the mRNA and protein level. Mol Cell Endocrinol 1994; 102:31-7. [PMID: 7926271 DOI: 10.1016/0303-7207(94)90094-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The expression of the autoantigen glutamate decarboxylase in islets of Langerhans was investigated under different culture conditions, which affect the functional activity of the beta-cell. Using immunoprecipitations and analyses of enzyme activity, an increase in glutamate decarboxylase was detected in rat islets cultured at a glucose concentration of 11 mmol/l compared with those cultured at 5.6 mmol/l glucose. To determine whether the change was induced at the level of mRNA expression, total RNA was extracted from rat islets cultured at 5.6 or 11 mmol/l glucose, reverse transcribed and amplified by the polymerase chain reaction. Comparative quantitation in a phosphor imager revealed a significantly higher (82%, P < 0.005) content of glutamate decarboxylase mRNA in islets cultured at 11 mmol/l glucose. In parallel, human recombinant interleukin-1 beta, and diazoxide were tested for their effects on the expression of glutamate decarboxylase. Islets cultured at 11 mmol/l glucose in the presence of 40 U/ml of interleukin-1 beta, showed a 63% decrease (P < 0.005) in enzyme activity compared with those cultured at 11 mmol/l glucose alone, and similar decreases were noted on analysis of glutamate decarboxylase biosynthesis and mRNA. Islets cultured at 11 mmol/l glucose in the presence of 22.5 mg/ml diazoxide exhibited a significant reduction in enzyme activity (59%; P < 0.001) compared with those cultured at 11 mmol/l glucose only. This reduction, however, was not accompanied by a decrease in the content of glutamate decarboxylase mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L A Velloso
- Department of Internal Medicine, University Hospital, Uppsala, Sweden
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17
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Lampeter EF, Seifert I, Lohmann D, Heise JW, Bertrams J, Christie MR, Kolb-Bachofen V, Kolb H. Inflammatory islet damage in patients bearing HLA-DR 3 and/or DR 4 haplotypes does not lead to islet autoimmunity. Diabetologia 1994; 37:471-5. [PMID: 8056184 DOI: 10.1007/s001250050134] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The hypothesis was tested that islet autoimmunity is induced by ongoing islet cell destruction in subjects with susceptibility genes HLA-DR 3 and/or DR 4. Sixty-one patients with confirmed chronic pancreatitis were analysed, 30 of whom expressed HLA-DR 3 and/or DR 4. Electron microscopy studies in 10 patients showed that the inflammatory process also affected islets, as recognisable from islet cell lysis, intrainsular fibrosis and immune cell infiltrates. None of the sera tested contained any of three markers of islet autoimmunity, ICA, IAA or GAD antibodies. A correlation was seen between the loss of exocrine function, as determined by the ALTAB-test, and of beta-cell function, as determined by the C-peptide response to i.v. glucagon. However, there was no preferential loss of beta-cell function in patients with HLA-DR 3 and/or DR 4. We conclude that islet cell destruction occurs during chronic pancreatitis, but does not trigger islet autoimmunity, even in the presence of HLA-DR 3 and/or DR 4.
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Affiliation(s)
- E F Lampeter
- Diabetes Research Institute, Heinrich-Heine-University, Düsseldorf, Germany
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18
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Chaillous L, Delamaire M, Elmansour A, Maugendre D, Rohmer V, Joseph MG, Lecomte P, Limal JM, Charbonnel B, Allannic H. Combined analysis of islet cell antibodies which cross-react with mouse pancreas, antibodies to the M(r) 64,000 islet protein, and antibodies to glutamate decarboxylase in subjects at risk for IDDM. Diabetologia 1994; 37:491-9. [PMID: 8056187 DOI: 10.1007/s001250050137] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
With regard to progression to diabetes, ICA cross-reactive with mouse pancreas, antibodies to the M(r) 64,000 islet antigen (64K), antibodies immunotrapping brain GAD activity, and IAA were analysed in 53 ICA-positive first-degree relatives of IDDM patients and 18 ICA-positive schoolchildren without a family history of diabetes. Sera from 29 (55%) relatives did not bind to mouse pancreas, whereas 24 (45%) displayed cross-species reaction. ICA titres on human and mouse pancreas were weakly correlated in the overall population (p < 0.05) but more strongly (p < 0.01) in only those subjects who displayed antibodies on tissues from both species. GAD and 64K antibodies were detected in 31% and 35% of relatives. In schoolchildren, the frequencies of cross-species reactive ICA (22%), GAD antibodies (6%), 64K antibodies (22%), and IAA (6%), were lower (p < 0.05) than in relatives. A strong correlation (p < 0.0001) was observed between GAD and 64K antibodies. GAD or 64K antibodies were strongly correlated with ICA on human pancreas (p < 0.0001) but poorly with ICA on mouse pancreas (p = 0.05). After pre-incubation of sera with brain homogenate, ICA titres were unaffected on mouse pancreas but reduced on human pancreas. ICA-positive subjects who displayed neither cross-species reactive ICA nor GAD or 64K antibodies were more frequent (p < 0.05) among schoolchildren than relatives, whereas subjects who displayed all antibody specificities were more numerous (p < 0.04) in relatives. All relatives with ICA binding only to human pancreas, as well as all schoolchildren, permanently displayed an AIRG higher than the first control percentile and remained non-diabetic.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L Chaillous
- Laboratoire Universitaire d'Immuno-Endocrinologie associé INRA/ENVN, Service d'Endocrinologie, Nantes, France
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19
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Wagner R, Genovese S, Bosi E, Becker F, Bingley PJ, Bonifacio E, Miles KA, Christie MR, Bottazzo GF, Gale EA. Slow metabolic deterioration towards diabetes in islet cell antibody positive patients with autoimmune polyendocrine disease. Diabetologia 1994; 37:365-71. [PMID: 8063036 DOI: 10.1007/bf00408472] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We studied metabolic progression to IDDM in a cohort of adults who are ICA-positive and have associated autoimmune endocrine disease or circulating organ-specific autoantibodies (the Polyendocrine Study). Of the 186 individuals recruited 27 developed overt diabetes after a median follow-up of 4.5 years (range 0.4-12). Of these, eight patients did not require insulin treatment until at least 6 months after clinical diagnosis, with an interval of 1.8 years (1.2-5.7). An IVGTT was performed in 38 subjects and 23 had sequential studies. Of the initial 38 subjects six developed diabetes and only three showed a loss of FPIR to glucose (below the first percentile of a normal control group) before clinical onset of the disease. An additional three subjects showed a loss of the FPIR, and all still have normal glucose tolerance after median follow-up of 28 months (22-95). A "whole" or "mixed" pattern of islet cell staining was found in five of the six patients who developed diabetes and antibodies against an islet 37 k-antigen were detectable in four patients, all of whom required insulin soon after diagnosis. A beta-cell "selective" ICA staining pattern was seen in 14 of 17 subjects who did not develop diabetes and the "mixed" pattern in only three. None of this group had detectable 37 k-antibodies. We conclude that metabolic deterioration is slow in polyendocrine patients, and that the IVGTT has less prognostic significance in this group than in first degree relatives of patients with IDDM.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- R Wagner
- Department of Immunology, London Hospital Medical College, UK
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20
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Bieg S, Seissler J, Herberg L, Northemann W, Scherbaum WA. GAD65 is recognized by T-cells, but not by antibodies from NOD-mice. Autoimmunity 1994; 17:189-94. [PMID: 7948603 DOI: 10.3109/08916939409010653] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Since the 64kDa-protein glutamic acid decarboxylase (GAD) is one of the major autoantigens in T-cell mediated Type 1 diabetes, its relevance as a T-cell antigen needs to be clarified. After isolation of splenic T-cells from non-obese diabetic (NOD) mice, a useful model for human Type 1 diabetes, we found that these T-cells proliferate spontaneously when incubated with human GAD65, but only marginally after incubation with GAD67, both recombinated in the baculovirus system. No effect was observed with non-diabetic NOD mice or with T-cells from H-2 identical NON-NOD-H-2g7 control mice. It has been published previously that NOD mice develop autoantibodies against a 64kDa protein detected with mouse beta cells. In immunoprecipitation experiments with sera from the same NOD mice and 35S-methionine-labelled GAD, no autoantibody binding could be detected. We conclude firstly that GAD65 is an important T-cell antigen which is relevant early in the development of Type 1 diabetes and secondly that there is an antigenic epitope in the human GAD65 molecule recognized by NOD T-cells, but not by NOD autoantibodies precipitating conformational epitopes. Our results therefore provide further evidence that GAD65 is a T-cell antigen in NOD mice, being possibly also involved in very early processes leading to the development of human Type 1 diabetes.
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Affiliation(s)
- S Bieg
- Department of Endocrinology, University Hospital Leipzig, FRG
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21
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Seissler J, Bieg S, Yassin N, Mauch L, Northemann W, Boehm BO, Scherbaum WA. Association between antibodies to the MR 67,000 isoform of glutamate decarboxylase (GAD) and type 1 (insulin-dependent) diabetes mellitus with coexisting autoimmune polyendocrine syndrome type II. Autoimmunity 1994; 19:231-8. [PMID: 7578849 DOI: 10.3109/08916939409071348] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
By using an immunoprecipitation assay, we analysed reactivity of autoantibodies to human recombinant GAD65 and GAD67 in sera from patients with autoimmune polyendocrine syndrome Type II (APS II) with and without Type 1 (insulin-dependent) diabetes mellitus (IDDM) compared to patients with organ-specific autoimmunity. Overall antibodies to GAD65 were correlated with IDDM in all study groups, whereas GAD67 antibodies were associated with IDDM when APS II coexists. Antibodies to GAD65 and GAD67 were detected in 13 (44.8%) and 7 (24.1%) out of 29 APS II patients with IDDM, but in only 4 (13.8%) and 2 (6.9%) out of 29 APS II patients without IDDM, respectively (p < 0.05). In short-standing IDDM (< 1 year), antibodies to GAD67 were significantly more frequent in patients with APS II (5 of 9 [55.6%] subjects) compared to matched diabetic patients without coexisting polyendocrinopathy (1 of 18 [5.6%] subjects) (p < 0.02). The levels of GAD65 (142 +/- 90 AU) and GAD67 antibodies (178 +/- 95 AU) were significantly higher in patients with polyglandular disease than in patients with isolated IDDM (91 +/- 85 AU and 93 +/- 57 AU) (p < 0.02). Interestingly, all 11 GAD67 antibody positive subjects also had GAD65 antibodies (p < 0.0001), and in 10 of 11 anti-GAD67 positive sera the GAD67 antibodies could be blocked by either GAD67 or GAD65, suggesting the presence of cross-reactive autoantibodies. No correlation was observed between GAD antibodies and age, sex or any particular associated autoimmune disease, besides IDDM.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J Seissler
- Department of Internal Medicine III, University of Leipzig, Germany
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22
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Butler MH, Solimena M, Dirkx R, Hayday A, De Camilli P. Identification of a dominant epitope of glutamic acid decarboxylase (GAD-65) recognized by autoantibodies in stiff-man syndrome. J Exp Med 1993; 178:2097-106. [PMID: 8245784 PMCID: PMC2191306 DOI: 10.1084/jem.178.6.2097] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Glutamic acid decarboxylase (GAD) is the enzyme that synthesizes the neurotransmitter gamma-aminobutyric acid (GABA) in neurons and in pancreatic beta cells. It is a major target of autoimmunity in Stiff-Man syndrome (SMS), a rare neurological disease, and in insulin-dependent diabetes mellitus. The two GAD isoforms, GAD-65 and GAD-67, are the products of two different genes. GAD-67 and GAD-65 are very similar to each other in amino acid sequence and differ substantially only at their NH2-terminal region. We have investigated the reactivity of autoantibodies of 30 Stiff-Man syndrome patients to GAD. All patient sera contained antibodies that recognize strongly GAD-65, but also GAD-67, when tested by immunoprecipitation on brain extracts and by immunoprecipitation or immunocytochemistry on cells transfected with either the GAD-65 or the GAD-67 gene. When tested by Western blotting, all patient sera selectively recognized GAD-65. Western blot analysis of deletion mutants of GAD-65 demonstrated that autoantibodies are directed predominantly against two regions of the GAD-65 molecule. All SMS sera strongly recognized a fragment contained between amino acid 475 and the COOH terminus (amino acid 585). Within this region, amino acids 475-484 and 571-585 were required for reactivity. The requirement of these two discontinuous segments implies that the epitope is influenced by conformation. This reactivity is similar to that displayed by the monoclonal antibody GAD 6, suggesting the presence of a single immunodominant epitope (SMS-E1) in this region of GAD-65. In addition, most SMS sera recognized at least one epitope (SMS-E2) in the NH2-terminal domain of GAD-65 (amino acids 1-95). The demonstration in SMS patients of a strikingly homogeneous humoral autoimmune response against GAD and the identification of dominant autoreactive target regions may help to elucidate the molecular mechanisms of GAD processing and presentation involved in GAD autoimmunity. Moreover, the reactivity reported here of GAD autoantibodies in SMS partially differs from the reactivity of GAD autoantibodies in insulin-dependent diabetes mellitus, suggesting a link between the pattern of humoral autoimmunity and the clinical condition.
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Affiliation(s)
- M H Butler
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510
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Affiliation(s)
- A Lernmark
- Department of Endocrinology, Karolinska Institute, Karolinska Hospital, Stockholm, Sweden
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24
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Seissler J, Amann J, Mauch L, Haubruck H, Wolfahrt S, Bieg S, Richter W, Holl R, Heinze E, Northemann W. Prevalence of autoantibodies to the 65- and 67-kD isoforms of glutamate decarboxylase in insulin-dependent diabetes mellitus. J Clin Invest 1993; 92:1394-9. [PMID: 8376591 PMCID: PMC288282 DOI: 10.1172/jci116714] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
We investigated the presence of autoantibodies to baculovirus-expressed human recombinant 65- and 67-kD isoforms of glutamate decarboxylase (GAD65 and GAD67) in insulin-dependent diabetes mellitus (IDDM). In the immunoprecipitation test using [35S]methionine-labeled GADs antibodies to GAD65 were detected in 13/15 (87%) islet cell antibody (ICA)-positive and in 1/35 (2.9%) ICA-negative first-degree relatives of patients with IDDM, in 6/11 (54.5%) ICA-positive nondiabetic schoolchildren, and in 35/50 (70%) patients with newly diagnosed IDDM. GAD67 antibodies were positive only in five (33%) of the ICA-positive relatives (P < 0.05) and in nine (18%) IDDM patients at onset (P < 0.00001). After onset of IDDM antibodies to GAD65 and GAD67 declined but were still positive in 25 and 9.4% of subjects with long-standing IDDM (> 10 yr). In all study groups antibodies to GAD67 were only detected in GAD65 antibody-positive sera. An immunotrapping enzyme activity assay for GAD65 antibodies was positive in 64/75 (85.3%) of sera that were GAD antibody positive in the immunoprecipitation test (r = 0.870, P < 0.0001). In two (2.7%) sera GAD65 antibodies that block GAD enzyme activity were found. Our data suggest that antibodies to GAD65 but not to GAD67 represent sensitive markers for preclinical and overt IDDM. The immunotrapping assay here described represents a valuable technique for specific and sensitive screening for GAD antibodies.
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Affiliation(s)
- J Seissler
- Department of Internal Medicine, University of Ulm, Germany
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25
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Christie MR, Hollands JA, Brown TJ, Michelsen BK, Delovitch TL. Detection of pancreatic islet 64,000 M(r) autoantigens in insulin-dependent diabetes distinct from glutamate decarboxylase. J Clin Invest 1993; 92:240-8. [PMID: 8325989 PMCID: PMC293578 DOI: 10.1172/jci116556] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Patients with insulin-dependent diabetes (IDDM) possess antibodies to islet proteins of M(r)-64,000. Potential autoantigens of this M(r) include glutamate decarboxylase (GAD) and 65 kD heat shock protein. We have detected two distinct antibody specificities in IDDM that bind 50,000 M(r) or 37,000/40,000 M(r) proteolytic fragments of 64,000 M(r) proteins. In this study, we investigated relationships of these proteolytic fragments to GAD and heat shock proteins. Polyclonal antibodies to GAD bound 50,000 M(r) fragments of islet antigen. Recombinant GAD65, but not GAD67, blocked binding to this antigen, suggesting that 50,000 M(r) fragments are derived from islet GAD65. In contrast, GAD antibodies did not recognize 37,000/40,000 M(r) fragments, and neither GAD isoforms blocked autoantibody binding to precursors of these fragments. The 37,000/40,000 M(r) fragments, but not the 50,000 M(r) fragments, were detected after trypsin treatment of immunoprecipitates from insulinoma cells that lacked expression of major GAD isoforms. Antibodies in IDDM did not bind native or trypsinized islet heat shock proteins. Thus, IDDM patients possess antibodies to GAD, but also distinct antibodies to a 64,000 M(r) protein that is not related to known GAD isoforms or heat shock proteins.
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Affiliation(s)
- M R Christie
- Nuffield Department of Clinical Biochemistry, John Radcliffe Hospital, Headington, Oxford, United Kingdom
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26
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Velloso LA, Kämpe O, Hallberg A, Christmanson L, Betsholtz C, Karlsson FA. Demonstration of GAD-65 as the main immunogenic isoform of glutamate decarboxylase in type 1 diabetes and determination of autoantibodies using a radioligand produced by eukaryotic expression. J Clin Invest 1993; 91:2084-90. [PMID: 8486775 PMCID: PMC288207 DOI: 10.1172/jci116431] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Plasmids containing cDNA for the rat 67- and 65-kD isoforms of glutamate decarboxylase (GAD-67 and GAD-65) were expressed in COS-cells, and lysates of [35S]methionine-labeled cells were used for immunoprecipitations. Sera from 38 patients with type 1 (insulin-dependent) diabetes mellitus, which precipitated a 64-kD antigen from rat islets, reacted with recombinant GAD-65 in relation to their anti-64-kD titers. The eight strongest sera also precipitated recombinant GAD-67, suggesting that certain epitopes are common to both isoforms. Subsequently, [35S]methionine-labeled GAD-65 was purified from COS cell lysates and employed in a binding assay with 50 sera of patients with recent onset of type 1 diabetes mellitus. 38 sera (76%) precipitated labeled GAD-65 with titers that correlated with islet cell antibodies (ICA), determined in a standard immunofluorescence assay. 2 sera were GAD positive but ICA negative, 4 were positive only for ICA, and 6 were negative for both GAD and ICA, as were the sera of 20 controls. The data illustrate that antibodies against GAD-65 are present in a majority of patients with type 1 diabetes mellitus and that autoantibodies against other islet cell antigens also exist. The radioligand-binding assay, which is convenient and sensitive for detecting GAD antibodies, will facilitate the screening of individuals with autoimmune islet cell disease.
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Affiliation(s)
- L A Velloso
- Department of Internal Medicine, University Hospital, Uppsala, Sweden
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27
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Richter W, Shi Y, Baekkeskov S. Autoreactive epitopes defined by diabetes-associated human monoclonal antibodies are localized in the middle and C-terminal domains of the smaller form of glutamate decarboxylase. Proc Natl Acad Sci U S A 1993; 90:2832-6. [PMID: 7681990 PMCID: PMC46190 DOI: 10.1073/pnas.90.7.2832] [Citation(s) in RCA: 116] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The gamma-aminobutyrate-synthesizing enzyme glutamate decarboxylase (GAD; L-glutamate 1-carboxy-lyase, EC 4.1.1.15) is a major target of autoantibodies associated with both early and late stages of pancreatic beta-cell destruction and development of type 1 diabetes. We have used five monoclonal anti-islet-cell antibodies (MICAs 1,2,3,4, and 6) derived from a newly diagnosed diabetic patient to probe the autoimmune epitopes in the enzyme. All the MICAs specifically recognized the smaller GAD protein, GAD65, and did not recognize the nonallelic GAD67 protein. A series of N-terminal, C-terminal, and internal deletion mutants, as well as protein footprinting, were used to identify the target regions in GAD65. Immunoprecipitation revealed two major native epitope areas in the GAD65 molecule. The first, defined by MICAs 1 and 3, is destroyed by deleting 41 amino acids at the C terminus but is also dependent on intact amino acids 244-295. This epitope (or epitopes) may span both middle and C-terminal domains of the protein. The second conformational epitope region, defined by MICAs 4 and 6, is dependent on intact amino acids 245-295 but is not affected by deletion of 110 amino acids at the C terminus and is therefore confined to domain(s) in the middle of the molecule. MICA 2 recognizes a linear epitope close to the C terminus. Thus, the N-terminal domain of GAD65, which differs most significantly from GAD67, does not harbor the MICA epitopes. Rather subtle amino acid differences in the middle and C-terminal domains define the GAD65-specific autoimmune epitopes. Analysis of sera from 10 type 1 diabetic patients suggests that MICAs 1, 3, 4, and 6 represent a common epitope recognition in this disease, whereas the MICA 2 epitope is rare. Furthermore, autoantibodies in some sera are restricted to the MICA 1/3 epitope, suggesting that this epitope may represent a single dominant epitope in the early phases of beta-cell autoimmunity.
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Affiliation(s)
- W Richter
- Department of Microbiology/Immunology, University of California, San Francisco 94143-0534
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28
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Christie MR. Characterization of distinct islet protein autoantigens associated with type 1 diabetes. Autoimmunity 1993; 15 Suppl:1-3. [PMID: 8218841 DOI: 10.3109/08916939309008848] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- M R Christie
- Nuffield Department of Clinical Biochemistry, John Radcliffe Hospital, Headington, Oxford, U.K
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29
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Velloso LA, Kämpe O, Eizirik DL, Hallberg A, Andersson A, Karlsson FA. Human autoantibodies react with glutamic acid decarboxylase antigen in human and rat but not in mouse pancreatic islets. Diabetologia 1993; 36:39-46. [PMID: 8436251 DOI: 10.1007/bf00399091] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The presence of one of the major targets for autoantibodies in Type 1 (insulin-dependent) diabetes mellitus, the enzyme glutamic acid decarboxylase, was studied in human, rat and mouse pancreatic tissue using immunoprecipitation and immunohistochemical techniques. Immunoprecipitation of glutamic acid decarboxylase was attempted with lysates of [35S]-methionine-labelled rat or mouse pancreatic islets using two different glutamic acid decarboxylase antisera, one mouse monoclonal antibody raised against the 65 kDa isoform of the enzyme, sera from six patients with Type 1 diabetes, one patient with stiff-man syndrome and sera from 19 non-obese diabetic mice. The same sera were used for immunoperoxidase staining of cryosections of human, rat or mouse pancreas. Using patient sera glutamic acid decarboxylase was detected by immunoprecipitations from isolated rat islets but not from islets of five different mouse strains tested, including the non-obese diabetic mouse. When using the non-obese diabetic mouse sera, glutamic acid decarboxylase could not be detected in either rat or mouse tissue. Immunoperoxidase staining demonstrated high levels of glutamic acid decarboxylase in human and rat pancreatic islets but low levels in mouse islets. Direct measurements of enzyme activity showed glutamic acid decarboxylase to be present in mouse islets at a level of about 40% of that in rat islets, and subsequent Western blot analyses indicated that mouse islets express the 67 kDa isoform, whereas as in rat islets both the 67 and 65 kDa isoforms are present.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L A Velloso
- Department of Internal Medicine, University Hospital, Uppsala, Sweden
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30
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Gorus FK, Sodoyez JC, Pipeleers DG, Keymeulen B, Foriers A, Van Schravendijk CF. Detection of autoantibodies against islet amyloid polypeptide in human serum. Lack of association with type 1 (insulin-dependent) diabetes mellitus, or with conditions favouring amyloid deposition in islets. The Belgian Diabetes Registry. Diabetologia 1992; 35:1080-6. [PMID: 1473619 DOI: 10.1007/bf02221685] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A radiobinding assay for the detection of autoantibodies against islet amyloid polypeptide was developed, analytically validated, and--in parallel with a similar assay for the detection of autoantibodies against insulin--applied to sera from recent-onset Type 1 (insulin-dependent) diabetic patients and from age- and sex-matched control subjects. There was no difference in islet amyloid polypeptide autoantibody titres between patient groups and matched control subjects, nor within subject groups according to age. At onset of Type 1 diabetes, elevated islet amyloid polypeptide-autoantibody levels (> 97th percentile of control subjects) were only detected in 1 of 30 patients aged 0-19 years and in 2 of 35 patients aged 20-39 years. By contrast, insulin autoantibodies were frequently demonstrated, in particular at onset of diabetes under age 20 (0-19 years: 18 of 30 patients; 20-39 years: 10 of 35 patients; p < 0.01 vs matched control subjects). Islet amyloid polypeptide autoantibodies were not detectable in 3 insulinoma patients nor in 37 patients (aged 33-70 years) with Type 2 diabetes (vs 1 of 40 in matched control subjects). In positive serum, adsorption onto protein A-Sepharose removed islet amyloid polypeptide binding activity, hereby confirming its antibody nature. In conclusion, Type 1 diabetes is associated with an age-dependent autoantibody reaction against insulin but not against islet amyloid polypeptide. Conditions associated with amyloid deposition in islets (Type 2 diabetes, insulinoma and ageing) do not favour the formation of autoantibodies against islet amyloid polypeptide.
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Affiliation(s)
- F K Gorus
- Department of Metabolism and Endocrinology, Vrije Universiteit Brussel, Belgium
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31
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Harrison LC. Islet cell antigens in insulin-dependent diabetes: Pandora's box revisited. IMMUNOLOGY TODAY 1992; 13:348-52. [PMID: 1466752 DOI: 10.1016/0167-5699(92)90170-c] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A major goal of research into IDDM has been the identification of the 'causative antigen'. As described in this article by Len Harrison, this reductionist aim is confounded by the fact that numerous candidate islet cell antigens have been described. He scrutinizes the credentials of these candidates and discusses the problem of using autoantibodies to identify causative antigens in a T-cell-mediated disease.
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Affiliation(s)
- L C Harrison
- Burnet Clinical Research Unit, Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Parkville, Victoria, Australia
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32
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DeAizpurua HJ, Harrison LC. Glutamic acid decarboxylase in insulin-dependent diabetes mellitus. DIABETES/METABOLISM REVIEWS 1992; 8:133-47. [PMID: 1425124 DOI: 10.1002/dmr.5610080205] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- H J DeAizpurua
- Burnet Clinical Research Unit, Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Parkville, Australia
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