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Sengupta S, Zhang J, Reed MC, Yu J, Kim A, Boronina TN, Board NL, Wrabl JO, Shenderov K, Welsh RA, Yang W, Timmons AE, Hoh R, Cole RN, Deeks SG, Siliciano JD, Siliciano RF, Sadegh-Nasseri S. A cell-free antigen processing system informs HIV-1 epitope selection and vaccine design. J Exp Med 2023; 220:e20221654. [PMID: 37058141 PMCID: PMC10114365 DOI: 10.1084/jem.20221654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 02/01/2023] [Accepted: 03/23/2023] [Indexed: 04/15/2023] Open
Abstract
Distinct CD4+ T cell epitopes have been associated with spontaneous control of HIV-1 replication, but analysis of antigen-dependent factors that influence epitope selection is lacking. To examine these factors, we used a cell-free antigen processing system that incorporates soluble HLA-DR (DR1), HLA-DM (DM), cathepsins, and full-length protein antigens for epitope identification by LC-MS/MS. HIV-1 Gag, Pol, Env, Vif, Tat, Rev, and Nef were examined using this system. We identified 35 novel epitopes, including glycopeptides. Epitopes from smaller HIV-1 proteins mapped to regions of low protein stability and higher solvent accessibility. HIV-1 antigens associated with limited CD4+ T cell responses were processed efficiently, while some protective epitopes were inefficiently processed. 55% of epitopes obtained from cell-free processing induced memory CD4+ T cell responses in HIV-1+ donors, including eight of 19 novel epitopes tested. Thus, an in vitro processing system utilizing the components of Class II processing reveals factors influencing epitope selection of HIV-1 and represents an approach to understanding epitope selection from non-HIV-1 antigens.
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Affiliation(s)
- Srona Sengupta
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- The Graduate Program in Immunology and Medical Scientist Training Program, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Josephine Zhang
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Madison C. Reed
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jeanna Yu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Aeryon Kim
- Department of Inflammation and Oncology and Genome Analysis Unit, Amgen Research, Amgen Inc., South San Francisco, CA, USA
| | - Tatiana N. Boronina
- Department of Biological Chemistry, Mass Spectrometry and Proteomics Facility, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Nathan L. Board
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - James O. Wrabl
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Kevin Shenderov
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Robin A. Welsh
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Weiming Yang
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Andrew E. Timmons
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Rebecca Hoh
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Robert N. Cole
- Department of Biological Chemistry, Mass Spectrometry and Proteomics Facility, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Steven G. Deeks
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Janet D. Siliciano
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Robert F. Siliciano
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Howard Hughes Medical Institute, Baltimore, MD, USA
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2
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Manoylov IK, Boneva GV, Doytchinova IA, Mihaylova NM, Tchorbanov AI. Suppression of Disease-Associated B Lymphocytes by GAD65 Epitope-Carrying Protein-Engineered Molecules in a Streptozotocin-Induced Mouse Model of Diabetes. Monoclon Antib Immunodiagn Immunother 2020; 38:201-208. [PMID: 31603741 DOI: 10.1089/mab.2019.0030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Type 1 diabetes mellitus is an autoimmune syndrome defined by the presence of autoreactive T and B cells, which results in destruction of insulin-producing beta cells. Autoantibodies against GAD65 (glutamic acid decarboxylase 65)-a membrane-bound enzyme on pancreatic beta cells, contribute to beta cells' destruction and the loss of pancreatic functions. Mouse FcγRIIb on B lymphocytes possesses an inhibitory effect on the activity of these cells. We hypothesized that it may be possible to suppress GAD65-specific B cells in mice with diabetes using chimeric molecules, containing an anti-FcγRIIb antibody, coupled to peptide B/T epitopes derived from the GAD65 protein. With these engineered chimeras, we expect to selectively co-cross-link the anti-GAD65-specific B cell receptor (BCR) and FcγRIIb, thus delivering a suppressive signal to the targeted B cells. An anti-FcγRIIb monoclonal antibody and two synthetic peptide epitopes derived from the GAD65 molecule were used for chimeras' construction. The suppressive activity of the engineered molecules was tested in vivo in mice with streptozotocin (STZ)-induced type 1 diabetes. These chimeric molecules exclusively bind disease-associated B cells by recognizing their GAD65-specific BCR and selectively deliver a strong inhibitory signal through their surface FcγRIIb receptors. A reduction in the number of anti-GAD65 IgG antibody-secreting plasmocytes and an increased percentage of apoptotic B lymphocytes were observed after treatment with protein-engineered antibodies of mice with STZ-induced type 1 diabetes.
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Affiliation(s)
- Iliyan Konstantinov Manoylov
- Laboratory of Experimental Immunology, Stefan Angelov Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Gabriela Valentinova Boneva
- Laboratory of Experimental Immunology, Stefan Angelov Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | | | - Nikolina Mihaylova Mihaylova
- Laboratory of Experimental Immunology, Stefan Angelov Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Andrey Ivanov Tchorbanov
- Laboratory of Experimental Immunology, Stefan Angelov Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.,National Institute of Immunology, Sofia, Bulgaria
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3
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Manoylov IK, Boneva GV, Doytchinova IA, Mihaylova NM, Tchorbanov AI. Protein-engineered molecules carrying GAD65 epitopes and targeting CD35 selectively down-modulate disease-associated human B lymphocytes. Clin Exp Immunol 2019; 197:329-340. [PMID: 31009057 DOI: 10.1111/cei.13305] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/16/2019] [Indexed: 12/29/2022] Open
Abstract
Type 1 diabetes mellitus is an autoimmune metabolic disorder characterized by chronic hyperglycemia, the presence of autoreactive T and B cells and autoantibodies against self-antigens. A membrane-bound enzyme on the pancreatic beta-cells, glutamic acid decarboxylase 65 (GAD65), is one of the main autoantigens in type 1 diabetes. Autoantibodies against GAD65 are potentially involved in beta-cell destruction and decline of pancreatic functions. The human complement receptor type 1 (CD35) on B and T lymphocytes has a suppressive activity on these cells. We hypothesized that it may be possible to eliminate GAD65-specific B cells from type 1 diabetes patients by using chimeric molecules, containing an anti-CD35 antibody, coupled to peptides resembling GAD65 B/T epitopes. These molecules are expected to selectively bind the anti-GAD65 specific B cells by the co-cross-linking of the immunoglobulin receptor and CD35 and to deliver a suppressive signal. Two synthetic peptides derived from GAD65 protein (GAD65 epitopes) and anti-CD35 monoclonal antibody were used for the construction of two chimeras. The immunomodulatory activity of the engineered antibodies was tested in vitro using peripheral blood mononuclear cells (PBMCs) from type 1 diabetes patients. A reduction in the number of anti-GAD65 IgG antibody-secreting plasma cells and increased percentage of apoptotic B lymphocytes was observed after treatment of these PBMCs with the engineered antibodies. The constructed chimeric molecules are able to selectively modulate the activity of GAD65-specific B lymphocytes and the production of anti-GAD65 IgG autoantibodies by co-cross-linking of the inhibitory CD35 and the B cell antigen receptor (BCR). This treatment presents a possible way to alter the autoimmune nature of these cells.
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Affiliation(s)
- I K Manoylov
- Laboratory of Experimental Immunology, Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - G V Boneva
- Laboratory of Experimental Immunology, Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - I A Doytchinova
- Faculty of Pharmacy, Medical University of Sofia, Sofia, Bulgaria
| | - N M Mihaylova
- Laboratory of Experimental Immunology, Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - A I Tchorbanov
- Laboratory of Experimental Immunology, Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.,National Institute of Immunology, Sofia, Bulgaria
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4
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Felton JL, Maseda D, Bonami RH, Hulbert C, Thomas JW. Anti-Insulin B Cells Are Poised for Antigen Presentation in Type 1 Diabetes. THE JOURNAL OF IMMUNOLOGY 2018; 201:861-873. [PMID: 29950508 DOI: 10.4049/jimmunol.1701717] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 05/23/2018] [Indexed: 12/29/2022]
Abstract
Early breaches in B cell tolerance are central to type 1 diabetes progression in mouse and man. Conventional BCR transgenic mouse models (VH125.Tg NOD) reveal the power of B cell specificity to drive disease as APCs. However, in conventional fixed IgM models, comprehensive assessment of B cell development is limited. To provide more accurate insight into the developmental and functional fates of anti-insulin B cells, we generated a new NOD model (VH125SDNOD) in which anti-insulin VDJH125 is targeted to the IgH chain locus to generate a small (1-2%) population of class switch-competent insulin-binding B cells. Tracking of this rare population in a polyclonal repertoire reveals that anti-insulin B cells are preferentially skewed into marginal zone and late transitional subsets known to have increased sensitivity to proinflammatory signals. Additionally, IL-10 production, characteristic of regulatory B cell subsets, is increased. In contrast to conventional models, class switch-competent anti-insulin B cells proliferate normally in response to mitogenic stimuli but remain functionally silent for insulin autoantibody production. Diabetes development is accelerated, which demonstrates the power of anti-insulin B cells to exacerbate disease without differentiation into Ab-forming or plasma cells. Autoreactive T cell responses in VH125SDNOD mice are not restricted to insulin autoantigens, as evidenced by increased IFN-γ production to a broad array of diabetes-associated epitopes. Together, these results independently validate the pathogenic role of anti-insulin B cells in type 1 diabetes, underscore their diverse developmental fates, and demonstrate the pathologic potential of coupling a critical β cell specificity to predominantly proinflammatory Ag-presenting B cell subsets.
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Affiliation(s)
- Jamie L Felton
- Division of Pediatric Endocrinology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Damian Maseda
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN 37232; and
| | - Rachel H Bonami
- Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University, Nashville, TN 37232
| | - Chrys Hulbert
- Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University, Nashville, TN 37232
| | - James W Thomas
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN 37232; and .,Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University, Nashville, TN 37232
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5
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Dai YD, Sheng H, Dias P, Jubayer Rahman M, Bashratyan R, Regn D, Marquardt K. Autoimmune Responses to Exosomes and Candidate Antigens Contribute to Type 1 Diabetes in Non-Obese Diabetic Mice. Curr Diab Rep 2017; 17:130. [PMID: 29080983 DOI: 10.1007/s11892-017-0962-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW The initial autoimmune trigger of type 1 diabetes (T1D) remains unclear. In non-obese diabetic (NOD) mice, islet inflammation starts early in life, suggesting the presence of an endogenous trigger for the spontaneous autoimmune response in this T1D mouse model. In this review, we argue that abnormal release of exosomes might be the trigger of the early inflammatory and autoimmune responses in the islets. RECENT FINDINGS Exosomes are nano-sized membrane complexes that are secreted by cells following fusion of late endosomes and/or multivesicular bodies with the plasma membrane. They are known extracellular messengers, communicating among neighboring cells via transporting large molecules from parent cells to recipient cells. Recent evidence demonstrates that these extracellular vesicles can modulate immune responses. It has been shown that insulinoma and islet mesenchymal stem cell-released exosomes are potent immune stimuli that can induce autoreactive B and T cells. Searching for candidate antigens in the exosomes identified endogenous retrovirus (ERV) Env and Gag antigens, which are homologous to an endogenous murine leukemia retrovirus. Autoantibodies and autoreactive T cells spontaneously developed in NOD mice can react to these retroviral antigens. More importantly, expression of the retroviral antigens in the islet mesenchymal stem cells is associated with disease susceptibility, and the expression is restricted to T1D-susceptible but not resistant mouse strains. Exosomes are novel autoimmune targets, carrying autoantigens that can stimulate innate and adaptive immune responses. An abnormal or excess release of exosomes, particularly those ones containing endogenous retroviral antigens might be responsible for triggering tissue-specific inflammatory and autoimmune responses.
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Affiliation(s)
- Yang D Dai
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA, USA.
- Biomedical Research Institute of Southern California, San Diego, CA, USA.
| | - Huiming Sheng
- Torrey Pines Institute for Molecular Studies, San Diego, CA, USA
- Tongren Hospital Affiliated to SJTU, School of Medicine, Shanghai, China
| | - Peter Dias
- Biomedical Research Institute of Southern California, San Diego, CA, USA
| | - M Jubayer Rahman
- Torrey Pines Institute for Molecular Studies, San Diego, CA, USA
| | - Roman Bashratyan
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA, USA
| | - Danielle Regn
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA, USA
| | - Kristi Marquardt
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA, USA
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6
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Baekkeskov S, Hubbell JA, Phelps EA. Bioengineering strategies for inducing tolerance in autoimmune diabetes. Adv Drug Deliv Rev 2017. [PMID: 28625830 DOI: 10.1016/j.addr.2017.06.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Type 1 diabetes is an autoimmune disease marked by the destruction of insulin-producing beta cells in the pancreatic islets. Strategies to delay onset or prevent the autoimmune recognition of beta cell antigens or T cell-mediated killing of beta cells have mainly focused on systemic immunomodulation and antigen-specific immunotherapy. To bridge the fields of type 1 diabetes immunology and biomaterials engineering, this article will review recent trends in the etiology of type 1 diabetes immunopathology and will focus on the contributions of emerging bioengineered strategies in the fight against beta cell autoimmunity in type 1 diabetes.
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Affiliation(s)
- Steinunn Baekkeskov
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Building SV 3826, Station 19, CH-1015 Lausanne, Switzerland; Departments of Medicine and Microbiology/Immunology, Diabetes Center, 513 Parnassus Ave, 20159, Box 0534, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Jeffrey A Hubbell
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Building SV 3826, Station 19, CH-1015 Lausanne, Switzerland; Institute for Molecular Engineering, University of Chicago, 5640 S Ellis Avenue, Chicago, IL 60615, USA
| | - Edward A Phelps
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Building SV 3826, Station 19, CH-1015 Lausanne, Switzerland; J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Drive, P.O. Box 116131, Gainesville, FL 32611, USA.
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7
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Bansal N, Hampe CS, Rodriguez L, Smith EO, Kushner J, Balasubramanyam A, Redondo MJ. DPD epitope-specific glutamic acid decarboxylase (GAD)65 autoantibodies in children with Type 1 diabetes. Diabet Med 2017; 34:641-646. [PMID: 26802570 PMCID: PMC4958605 DOI: 10.1111/dme.13077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/19/2016] [Indexed: 12/18/2022]
Abstract
AIM To study whether DPD epitope-specific glutamate decarboxylase autoantibodies are found more frequently in children with milder forms of Type 1 diabetes. METHODS We prospectively evaluated 75 children with new-onset autoimmune Type 1 diabetes, in whom we collected demographic, anthropometric and clinical data and measured islet autoantibodies. Glutamate decarboxylase 65 autoantibody-positive samples were analysed for epitope specificities using recombinant Fab against the DPD-defined epitope of glutamate decarboxylase 65. RESULTS After adjustment for age, positive DPD epitope recognition was significantly associated with higher C-peptide levels at onset (P = 0.02, r2 =0.21, n = 35), and high DPD recognition in the highest quartile tended to be associated with HbA1c ≤ 53 mmol/mol (7%) at the last follow-up [mean (sd) follow-up 1.3 (0.4) years; P = 0.07; for the model, P = 0.044, n = 30)]. Age- and sex-adjusted BMI percentile was significantly correlated with recognition of the DPD-defined epitope (P < 0.03, r2 =0.14, n = 34), but this correlation was driven by the older age group (age ≥ 10 years; P = 0.016, r2 =0.27, n = 21) and was not significant in younger children (P = 0.93, n = 13). There were no independent associations with sex, race/ethnicity, diabetic ketoacidosis, HbA1c , HLA DR3-DQ2/DR4-DQ8 or autoantibody number. CONCLUSIONS Our findings suggest that recognition of the DPD-defined glutamate decarboxylase 65 autoantibody epitope at Type 1 diabetes onset is directly associated with β-cell function, BMI and age, which supports the hypothesis that immunological factors contribute to the clinical heterogeneity of Type 1 diabetes. Larger studies relating epitope-specific glutamate decarboxylase 65 autoantibody to clinical phenotype in children with Type 1 diabetes are warranted.
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Affiliation(s)
- N. Bansal
- Department of Pediatrics, Section of Diabetes and Endocrinology, Texas Children’s Hospital, Baylor College of Medicine, Houston, TX
| | - C. S. Hampe
- Department of Medicine, University of Washington, Seattle, WA
| | - L. Rodriguez
- Department of Pediatrics, Section of Pediatric Endocrinology, Children’s Hospital of San Antonio, Baylor College of Medicine, San Antonio, TX
| | - E. O’Brian Smith
- Children’s Nutrition Research Center, Baylor College of Medicine, Houston, TX
| | - J. Kushner
- Department of Pediatrics, Section of Diabetes and Endocrinology, Texas Children’s Hospital, Baylor College of Medicine, Houston, TX
| | - A. Balasubramanyam
- Translational Metabolism Unit, Diabetes Research Center, Division of Diabetes, Endocrinology and Metabolism, Baylor College of Medicine, Houston, TX, USA
| | - M. J. Redondo
- Department of Pediatrics, Section of Diabetes and Endocrinology, Texas Children’s Hospital, Baylor College of Medicine, Houston, TX
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8
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Phelps EA, Cianciaruso C, Michael IP, Pasquier M, Kanaani J, Nano R, Lavallard V, Billestrup N, Hubbell JA, Baekkeskov S. Aberrant Accumulation of the Diabetes Autoantigen GAD65 in Golgi Membranes in Conditions of ER Stress and Autoimmunity. Diabetes 2016; 65:2686-99. [PMID: 27284108 PMCID: PMC5001175 DOI: 10.2337/db16-0180] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 05/27/2016] [Indexed: 02/06/2023]
Abstract
Pancreatic islet β-cells are particularly susceptible to endoplasmic reticulum (ER) stress, which is implicated in β-cell dysfunction and loss during the pathogenesis of type 1 diabetes (T1D). The peripheral membrane protein GAD65 is an autoantigen in human T1D. GAD65 synthesizes γ-aminobutyric acid, an important autocrine and paracrine signaling molecule and a survival factor in islets. We show that ER stress in primary β-cells perturbs the palmitoylation cycle controlling GAD65 endomembrane distribution, resulting in aberrant accumulation of the palmitoylated form in trans-Golgi membranes. The palmitoylated form has heightened immunogenicity, exhibiting increased uptake by antigen-presenting cells and T-cell stimulation compared with the nonpalmitoylated form. Similar accumulation of GAD65 in Golgi membranes is observed in human β-cells in pancreatic sections from GAD65 autoantibody-positive individuals who have not yet progressed to clinical onset of T1D and from patients with T1D with residual β-cell mass and ongoing T-cell infiltration of islets. We propose that aberrant accumulation of immunogenic GAD65 in Golgi membranes facilitates inappropriate presentation to the immune system after release from stressed and/or damaged β-cells, triggering autoimmunity.
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Affiliation(s)
- Edward A Phelps
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Chiara Cianciaruso
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland Graduate Program in Biotechnology and Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Iacovos P Michael
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Miriella Pasquier
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Jamil Kanaani
- Departments of Medicine, Microbiology and Immunology and Diabetes Center, University of California San Francisco, San Francisco, CA
| | - Rita Nano
- Diabetes Research Institute, IRCCS, Pancreatic Islet Processing Facility, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Vanessa Lavallard
- Cell Isolation and Transplantation Center, Faculty of Medicine, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Nils Billestrup
- Section of Cellular and Metabolic Research, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jeffrey A Hubbell
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland Graduate Program in Biotechnology and Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland Institute for Molecular Engineering, University of Chicago, Chicago, IL
| | - Steinunn Baekkeskov
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland Graduate Program in Biotechnology and Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland Departments of Medicine, Microbiology and Immunology and Diabetes Center, University of California San Francisco, San Francisco, CA
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La Torre D. Immunobiology of beta-cell destruction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 771:194-218. [PMID: 23393680 DOI: 10.1007/978-1-4614-5441-0_16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Type 1 diabetes is a chronic disease characterized by severe insulin deficiency and hyperglycemia, due to autoimmune destruction of pancreatic islets of Langerhans. A susceptible genetic background is necessary, but not sufficient, for the development of the disease. Epidemiological and clinical observations underscore the importance of environmental factors as triggers of type 1 diabetes, currently under investigation. Islet-specific autoantibodies precede clinical onset by months to years and are established tools for risk prediction, yet minor players in the pathogenesis of the disease. Many efforts have been made to elucidate disease-relevant defects in the key immune effectors of islet destruction, from the early failure of specific tolerance to the vicious circle of destructive insulitis. However, the events triggering islet autoimmunity as well as the transition to overt diabetes are still largely unknown, making prevention and treatment strategies still a challenge.
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Affiliation(s)
- Daria La Torre
- Lund University, Clinical Research Center (CRC), Department of Clinical Sciences, Malmö, Sweden.
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10
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Delli AJ, Vaziri-Sani F, Lindblad B, Elding-Larsson H, Carlsson A, Forsander G, Ivarsson SA, Ludvigsson J, Kockum I, Marcus C, Samuelsson U, Örtqvist E, Groop L, Bondinas GP, Papadopoulos GK, Lernmark Å. Zinc transporter 8 autoantibodies and their association with SLC30A8 and HLA-DQ genes differ between immigrant and Swedish patients with newly diagnosed type 1 diabetes in the Better Diabetes Diagnosis study. Diabetes 2012; 61:2556-64. [PMID: 22787139 PMCID: PMC3447907 DOI: 10.2337/db11-1659] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We examined whether zinc transporter 8 autoantibodies (ZnT8A; arginine ZnT8-RA, tryptophan ZnT8-WA, and glutamine ZnT8-QA variants) differed between immigrant and Swedish patients due to different polymorphisms of SLC30A8, HLA-DQ, or both. Newly diagnosed autoimmune (≥1 islet autoantibody) type 1 diabetic patients (n = 2,964, <18 years, 55% male) were ascertained in the Better Diabetes Diagnosis study. Two subgroups were identified: Swedes (n = 2,160, 73%) and immigrants (non-Swedes; n = 212, 7%). Non-Swedes had less frequent ZnT8-WA (38%) than Swedes (50%), consistent with a lower frequency in the non-Swedes (37%) of SLC30A8 CT+TT (RW+WW) genotypes than in the Swedes (54%). ZnT8-RA (57 and 58%, respectively) did not differ despite a higher frequency of CC (RR) genotypes in non-Swedes (63%) than Swedes (46%). We tested whether this inconsistency was due to HLA-DQ as 2/X (2/2; 2/y; y is anything but 2 or 8), which was a major genotype in non-Swedes (40%) compared with Swedes (14%). In the non-Swedes only, 2/X (2/2; 2/y) was negatively associated with ZnT8-WA and ZnT8-QA but not ZnT8-RA. Molecular simulation showed nonbinding of the relevant ZnT8-R peptide to DQ2, explaining in part a possible lack of tolerance to ZnT8-R. At diagnosis in non-Swedes, the presence of ZnT8-RA rather than ZnT8-WA was likely due to effects of HLA-DQ2 and the SLC30A8 CC (RR) genotypes.
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Affiliation(s)
- Ahmed J Delli
- Department of Clinical Sciences, Diabetes and Celiac Diseases, Lund University, Malmö, Sweden.
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11
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Hampe CS. Protective role of anti-idiotypic antibodies in autoimmunity--lessons for type 1 diabetes. Autoimmunity 2012; 45:320-31. [PMID: 22288464 DOI: 10.3109/08916934.2012.659299] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Circulating autoantibodies to beta cell antigens are present in the majority of patients with Type 1 diabetes. These autoantibodies can be detected before and at time of clinical diagnosis of disease. Although the role of autoantibodies in the pathogenesis of the disease is debated, their presence indicates a dysregulation of the humoral immune response. Mechanisms regulating autoantibodies in Type 1 diabetes are not well understood. In contrast, in other autoimmune diseases there is acceptance that autoantibodies are regulated not only by antigen but also by other antibodies that bind to the antigen-binding site of these autoantibodies (anti-idiotypic antibodies). The proposed purpose of this network is to maintain an equilibrium between autoantibodies and their anti-idiotypic antibodies, preventing autoimmunity, while allowing a robust response to exogenous antigen. Anti-idiotypic antibodies regulate both autoantibody binding and their levels by a) neutralizing autoantibodies, and b) inhibiting the secretion of autoantibodies. Because it has been proposed that the B lymphocytes that produce autoantibodies function as autoantigen presenting cells, inhibiting their binding to autoantigen by anti-idiotypic antibodies may prevent development of autoimmune disease. This hypothesis is supported by the presence of anti-idiotypic antibodies in healthy individuals and in patients in remission from autoimmune diseases, and by the lack of anti-idiotypic antibodies during active disease. We recently reported the presence of autoantibodies to glutamate decarboxylase in the majority of healthy individuals, where their binding to autoantigen is prevented by anti-idiotypic antibodies. These anti-idiotypic antibodies are absent at clinical diagnosis of Type 1 diabetes, revealing the presence of autoantibodies. Type 1 diabetes (T1D) is an autoimmune disease characterized by the dysfunction and destruction of insulin-producing beta cells by autoreactive T cells. Although much progress has been made towards understanding the respective roles of effector and regulatory T cells in this beta cell destruction, the development of autoantibodies to beta cell proteins is widely considered simply a by-product of the autoimmune destruction of the beta cells, rather than having an active role in the pathogenesis. This view is starting to change based on increasing recognition that autoantibodies can have defined roles in other autoimmune diseases, and the emergence of new data on their role in T1D. This exploration of the role of autoantibodies in autoimmune disease has been spurred, in part, by increasing recognition that development of autoimmune diseases is influenced by regulatory antibodies (anti-idiotypic antibodies) directed against the unique binding site of autoantibodies. This review provides an overview of the development and function of these anti-idiotypic antibodies, and present evidence supporting their role in the development of autoimmune diseases. Finally, we conclude this review with a model of the events that may cause loss of anti-idiotypic antibodies and the implications for the development of T1D.
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Affiliation(s)
- Christiane S Hampe
- Department of Medicine, University of Washington, Seattle, WA 98109, USA.
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Abstract
The role of B cells in autoimmune diseases involves different cellular functions, including the well-established secretion of autoantibodies, autoantigen presentation and ensuing reciprocal interactions with T cells, secretion of inflammatory cytokines, and the generation of ectopic germinal centers. Through these mechanisms B cells are involved both in autoimmune diseases that are traditionally viewed as antibody mediated and also in autoimmune diseases that are commonly classified as T cell mediated. This new understanding of the role of B cells opened up novel therapeutic options for the treatment of autoimmune diseases. This paper includes an overview of the different functions of B cells in autoimmunity; the involvement of B cells in systemic lupus erythematosus, rheumatoid arthritis, and type 1 diabetes; and current B-cell-based therapeutic treatments. We conclude with a discussion of novel therapies aimed at the selective targeting of pathogenic B cells.
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Affiliation(s)
- Christiane S. Hampe
- Department of Medicine, University of Washington, SLU-276, 850 Republican, Seattle, WA 98109, USA
- *Christiane S. Hampe:
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Abstract
The clinical onset of type 1 diabetes or autoimmune diabetes occurs after a prodrome of islet autoimmunity. The warning signals for the ensuing loss of pancreatic islet beta cells are autoantibodies against insulin, GAD65, IA-2 and ZnT8, alone or in combinations. Autoantibodies against, for example, insulin alone have only a minor risk of type 1 diabetes. However, progression to clinical onset is increased by the induction of multiple islet autoantibodies. At the time of clinical onset, insulitis may be manifest, which seems to reduce the efficacy of immunosuppression. Autoantigen-specific immunotherapy with alum-formulated GAD65 (Diamyd(®)) shows promise to reduce the loss of beta-cell function after the clinical onset of type 1 diabetes. The mechanisms are unclear but may involve the induction of T regulatory cells, which may suppress islet autoantigen reactivity. Past and ongoing clinical trials have been safe. Future clinical trials, perhaps as combination autoantigen-specific immunotherapy, may increase the efficacy in preventing the clinical onset in subjects with islet autoantibodies or preserve residual beta-cell function in patients newly diagnosed with type 1 diabetes.
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Affiliation(s)
- H E Larsson
- Department of Clinical Sciences, Lund University/CRC, Skåne University Hospital SUS, Malmö, Sweden
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15
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Wong FS, Hu C, Xiang Y, Wen L. To B or not to B—pathogenic and regulatory B cells in autoimmune diabetes. Curr Opin Immunol 2010; 22:723-31. [DOI: 10.1016/j.coi.2010.10.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2010] [Revised: 10/03/2010] [Accepted: 10/04/2010] [Indexed: 02/01/2023]
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16
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Ortqvist E, Brooks-Worrell B, Lynch K, Radtke J, Bekris LM, Kockum I, Agardh CD, Cilio CM, Lethagen AL, Persson B, Lernmark A, Reichow J, Oak S, Palmer JP, Hampe CS. Changes in GAD65Ab-specific antiidiotypic antibody levels correlate with changes in C-peptide levels and progression to islet cell autoimmunity. J Clin Endocrinol Metab 2010; 95:E310-8. [PMID: 20685858 PMCID: PMC2968730 DOI: 10.1210/jc.2010-0785] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2010] [Accepted: 07/06/2010] [Indexed: 01/11/2023]
Abstract
CONTEXT The previously reported absence of 65-kDa glutamate decarboxylase antibody (GAD65Ab)-specific antiidiotypic antibodies (anti-Id) in type 1 diabetes (T1D) patients at clinical onset could be due to an inability to mount an antibody response to GAD65Ab or a longitudinal decline in anti-Id levels. OBJECTIVE AND DESIGN We investigated anti-Id levels in longitudinal samples obtained from T1D patients (n = 41) (clinical diagnosis - 12 months), and latent autoimmune diabetes in adults (LADA) patients (n = 32) who received alum-formulated human recombinant GAD65 (baseline - 12 months). We also determined anti-Id levels in a small cohort of Type 2 diabetes patients during their development of autoimmune T cell responses. RESULTS At clinical onset T1D patients presented no or low anti-Id levels. However, 22/41 T1D patients showed ≥50% increase in GAD65Ab-specific anti-Id levels during follow-up; peaking at 3 (n = 1), 6 (n = 10), 9 (n = 10), or 12 (n = 1) months. Increasing anti-Id levels marked patients who experienced a temporary increase in C-peptide levels. Anti-Id levels correlated significantly with glycated hemoglobin and C-peptide levels at 6 and 9 months (P values ranged from <0.001 to <0.05). In LADA patients receiving placebo, anti-Id levels declined in seven of nine patients, whereas four of five patients receiving 20 μg alum-formulated human recombinant GAD65 showed increasing anti-Id levels. Changes in anti-Id and C-peptide levels closely correlated (P < 0.0001). The significant decline in anti-Id levels (P = 0.03) in T2D patients developing T cell autoimmune responses supports our hypothesis that declining anti-Id levels are associated with developing islet autoimmunity. CONCLUSIONS The close association between GAD65Ab-specific anti-Id levels and β-cell function may provide a novel marker for the progression of autoimmune diabetes.
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Affiliation(s)
- E Ortqvist
- Department of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden
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Wang H, Yang J, Jin L, Feng J, Lu Y, Sun Y, Li T, Cao R, Wu J, Fan H, Liu J. Immunotherapy of autoimmune diabetes by nasal administration of tandem glutamic acid decarboxylase 65 peptides. Immunol Invest 2010; 38:690-703. [PMID: 19860582 DOI: 10.3109/08820130903124770] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Mucosally induced tolerance is an attractive strategy for immunotherapy of autoimmune diseases. Treatment of nonobese diabetic (NOD) mice with a mixture of autoantigen peptides is better geared toward slowing the progression of late stage type 1 diabetes (T1D) than treatment with any of the peptides alone. In this study, we constructed a fusion protein CTB-GADIII. It contains cholera toxin B subunit (CTB) and three tandem peptides derived from glutamic acid decarboxylase 65 (GAD65), p217-236, p524-538 and p290-306. The purified renatured pentamer fusion protein was effective in inhibiting the development of diabetes in NOD mice when the mice were nasally immunized three times (8w, 10w and 12w). Prevention of diabetes was associated with special humoral immune tolerance against tandem peptides GADIII. These data indicate that using CTB as a vaccine carrier, tandem GAD65 peptides can prevent T1D in NOD mice at the late stage of disease.
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Affiliation(s)
- Huaqian Wang
- Laboratory of Minigene Pharmacy, School of Life Science and Technology, China Pharmaceutical University, Tongjia Xiang, Nanjing 210009, PR China.
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Rizzi M, Knoth R, Hampe CS, Lorenz P, Gougeon ML, Lemercier B, Venhoff N, Ferrera F, Salzer U, Thiesen HJ, Peter HH, Walker UA, Eibel H. Long-lived plasma cells and memory B cells produce pathogenic anti-GAD65 autoantibodies in Stiff Person Syndrome. PLoS One 2010; 5:e10838. [PMID: 20520773 PMCID: PMC2877104 DOI: 10.1371/journal.pone.0010838] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Accepted: 04/22/2010] [Indexed: 11/25/2022] Open
Abstract
Stiff person syndrome (SPS) is a rare, neurological disorder characterized by sudden cramps and spasms. High titers of enzyme-inhibiting IgG autoantibodies against the 65 kD isoform of glutamic acid decarboxylase (GAD65) are a hallmark of SPS, implicating an autoimmune component in the pathology of the syndrome. Studying the B cell compartment and the anti-GAD65 B cell response in two monozygotic twins suffering from SPS, who were treated with the B cell-depleting monoclonal anti-CD20 antibody rituximab, we found that the humoral autoimmune response in SPS is composed of a rituximab-sensitive part that is rapidly cleared after treatment, and a rituximab-resistant component, which persists and acts as a reservoir for autoantibodies inhibiting GAD65 enzyme activity. Our data show that these potentially pathogenic anti-GAD65 autoantibodies are secreted by long-lived plasma cells, which may either be persistent or develop from rituximab-resistant memory B lymphocytes. Both subsets represent only a fraction of anti-GAD65 autoantibody secreting cells. Therefore, the identification and targeting of this compartment is a key factor for successful treatment planning of SPS and of similar autoimmune diseases.
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Affiliation(s)
- Marta Rizzi
- Department of Rheumatology and Clinical Immunology, University Medical Center Freiburg, Freiburg, Germany
- Centre of Chronic Immunodeficiency, University Medical Center Freiburg, Freiburg, Germany
- Clinical Research Unit for Rheumatology, University Medical Center Freiburg, Freiburg, Germany
| | - Rolf Knoth
- Department of Neuropathology, Institute of Pathology, University Medical Center Freiburg, Freiburg, Germany
| | - Christiane S. Hampe
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Peter Lorenz
- Institute of Immunology, University of Rostock, Rostock, Germany
| | - Marie-Lise Gougeon
- Institut Pasteur, Antiviral Immunity, Biotherapy and Vaccine Unit, Paris, France
| | - Brigitte Lemercier
- Institut Pasteur, Antiviral Immunity, Biotherapy and Vaccine Unit, Paris, France
| | - Nils Venhoff
- Department of Rheumatology and Clinical Immunology, University Medical Center Freiburg, Freiburg, Germany
- Centre of Chronic Immunodeficiency, University Medical Center Freiburg, Freiburg, Germany
| | - Francesca Ferrera
- Centre of Excellence for Biomedical Research, University of Genova, Genova, Italy
| | - Ulrich Salzer
- Department of Rheumatology and Clinical Immunology, University Medical Center Freiburg, Freiburg, Germany
- Centre of Chronic Immunodeficiency, University Medical Center Freiburg, Freiburg, Germany
| | | | - Hans-Hartmut Peter
- Department of Rheumatology and Clinical Immunology, University Medical Center Freiburg, Freiburg, Germany
- Centre of Chronic Immunodeficiency, University Medical Center Freiburg, Freiburg, Germany
| | - Ulrich A. Walker
- Department of Rheumatology at Basel University, Basel, Switzerland
| | - Hermann Eibel
- Department of Rheumatology and Clinical Immunology, University Medical Center Freiburg, Freiburg, Germany
- Centre of Chronic Immunodeficiency, University Medical Center Freiburg, Freiburg, Germany
- Clinical Research Unit for Rheumatology, University Medical Center Freiburg, Freiburg, Germany
- * E-mail:
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La Torre D, Lernmark A. Immunology of beta-cell destruction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 654:537-83. [PMID: 20217514 DOI: 10.1007/978-90-481-3271-3_24] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The pancreatic islet beta-cells are the target for an autoimmune process that eventually results in an inability to control blood glucose due to the lack of insulin. The different steps that eventually lead to the complete loss of the beta-cells are reviewed to include the very first step of a triggering event that initiates the development of beta-cell autoimmunity to the last step of appearance of islet-cell autoantibodies, which may mark that insulitis is about to form. The observations that the initial beta-cell destruction by virus or other environmental factors triggers islet autoimmunity not in the islets but in the draining pancreatic lymph nodes are reviewed along with possible basic mechanisms of loss of tolerance to islet autoantigens. Once islet autoimmunity is established the question is how beta-cells are progressively killed by autoreactive lymphocytes which eventually results in chronic insulitis. Many of these series of events have been dissected in spontaneously diabetic mice or rats, but controlled clinical trials have shown that rodent observations are not always translated into mechanisms in humans. Attempts are therefore needed to clarify the step 1 triggering mechanisms and the step to chronic autoimmune insulitis to develop evidence-based treatment approaches to prevent type 1 diabetes.
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Affiliation(s)
- Daria La Torre
- Lund University, CRC, Department of Clinical Sciences, University Hospital MAS, SE-205 02, Malmö, Sweden.
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20
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Côrte-Real J, Duarte N, Tavares L, Penha-Gonçalves C. Autoimmunity triggers in the NOD mouse: a role for natural auto-antibody reactivities in type 1 diabetes. Ann N Y Acad Sci 2009; 1173:442-8. [PMID: 19758184 DOI: 10.1111/j.1749-6632.2009.04661.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The nonobese diabetic mouse (NOD) is widely used as a model to study human type 1 diabetes (T1D). In the NOD mouse T1D is a T cell-mediated autoimmune disease of complex etiology in which B cells play an essential role. One of the major unresolved issues in T1D is the genetic and/or environmental factors that trigger the autoimmune reaction. In the NOD mouse, as in humans, auto-antibodies to pancreatic islets are present at early ages and are highly correlated to diabetes progression, but their etiological role has long been disputed. NOD auto-antibodies have the characteristics of a natural repertoire, and B1 cells, the main natural antibody producers, exhibit functional differences in this strain that could have consequences for disease determination. Using a genetic approach, we propose to test if the NOD natural auto-antibody repertoire includes innate reactivities that participate in diabetes pathogenesis by promoting insulitis initiation.
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Cerebrospinal fluid T cell responses against glutamic acid decarboxylase 65 in patients with stiff person syndrome. J Autoimmun 2009; 32:24-32. [DOI: 10.1016/j.jaut.2008.10.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Revised: 10/03/2008] [Accepted: 10/07/2008] [Indexed: 01/02/2023]
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Lyons JA, Ramsbottom MJ, Mikesell RJ, Cross AH. B cells limit epitope spreading and reduce severity of EAE induced with PLP peptide in BALB/c mice. J Autoimmun 2008; 31:149-55. [PMID: 18539432 DOI: 10.1016/j.jaut.2008.04.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 04/15/2008] [Accepted: 04/26/2008] [Indexed: 10/22/2022]
Abstract
The role of B cells and antibody in experimental autoimmune encephalomyelitis (EAE) appears to differ based on the identity and state (protein vs. encephalitogenic peptide) of the inducing antigen and the strain of mouse utilized. The involvement of B cells in the induction of EAE by peptides of proteolipid protein (PLP) in BALB/c mice was investigated. Wild-type and B cell-deficient (B cell-/-) mice on the BALB/c background were immunized with overlapping PLP peptides, and the disease course was followed. Although incidence and onset of PLP(180-199)-induced EAE was similar in WT and B cell-/- mice, the clinical course was more severe in B cell-/- mice. During acute disease, proliferation and interferon-gamma production by lymphoid cells from both strains were similar and were elicited predominantly in response to the immunizing antigen. However, during chronic disease lymphoid cells isolated from B cell-/- mice proliferated to a greater extent and produced more interferon-gamma in response to the overlapping peptide PLP185-206 and to the smaller internal peptide PLP185-199 than did WT mice. These data suggest that B cells regulate PLP-induced EAE in BALB/c mice through control of epitope spreading.
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Affiliation(s)
- Jeri-Anne Lyons
- Department of Neurology & Neurosurgery, Washington University, 660 S. Euclid, Box 8111, Saint Louis, MO 63110, USA.
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23
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Abstract
The repertoire of known autoantigens is limited to a very small proportion of all human proteins, and the reason why only some proteins become autoantigens is unclear, but is likely associated with structural features. The 65kDa isoform of the enzyme glutamic acid decarboxylase (GAD65) is a major autoantigen in type I diabetes, and in various neurological diseases, whereas the closely related isoform, GAD67, is rarely antigenic. Conformational epitopes of GAD65 have been mapped using human monoclonal antibodies to GAD65 and GAD mutated by GAD65/67 sequence exchanges or point mutations, but these studies have been limited by a lack of structural information. The recent publication of crystal structures for the two isoforms has shown that the N-, C- and middle domains that have been identified previously as likely epitope regions are closely associated within the GAD dimer. Two major epitope regions, ctc1 and ctc2, have been identified in the C-terminal domain of GAD65, that encompass N- and C-terminal residues, and middle and C-terminal residues respectively. These regions are highly flexible compared with the equivalent regions in GAD67, and T cell epitopes have been localized to the same surface region of GAD65. Comparative analysis of these two structurally similar isoforms, GAD65 and GAD67, only one of which is autoantigenic should provide new insights into the provocations to autoimmunity.
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Affiliation(s)
- Gustavo Fenalti
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Melbourne, VIC 3800, Australia
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Fenalti G, Hampe CS, Arafat Y, Law RHP, Banga JP, Mackay IR, Whisstock JC, Buckle AM, Rowley MJ. COOH-terminal clustering of autoantibody and T-cell determinants on the structure of GAD65 provide insights into the molecular basis of autoreactivity. Diabetes 2008; 57:1293-301. [PMID: 18184926 DOI: 10.2337/db07-1461] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE To gain structural insights into the autoantigenic properties of GAD65 in type 1 diabetes, we analyzed experimental epitope mapping data in the context of the recently determined crystal structures of GAD65 and GAD67, to allow "molecular positioning" of epitope sites for B- and T-cell reactivity. RESEARCH DESIGN AND METHODS Data were assembled from analysis of reported effects of mutagenesis of GAD65 on its reactivity with a panel of 11 human monoclonal antibodies (mAbs), supplemented by use of recombinant Fab to cross-inhibit reactivity with GAD65 by radioimmunoprecipitation of the same mAbs. RESULTS The COOH-terminal region on GAD65 was the major autoantigenic site. B-cell epitopes were distributed within two separate clusters around different faces of the COOH-terminal domain. Inclusion of epitope sites in the pyridoxal phosphate-and NH(2)-terminal domains was attributed to the juxtaposition of all three domains in the crystal structure. Epitope preferences of different mAbs to GAD65 aligned with different clinical expressions of type 1 diabetes. Epitopes for four of five known reactive T-cell sequences restricted by HLA DRB1*0401 were aligned to solvent-exposed regions of the GAD65 structure and colocalized within the two B-cell epitope clusters. The continuous COOH-terminal epitope region of GAD65 was structurally highly flexible and therefore differed markedly from the equivalent region of GAD67. CONCLUSIONS Structural features could explain the differing antigenicity, and perhaps immunogenicity, of GAD65 versus GAD67. The proximity of B- and T-cell epitopes within the GAD65 structure suggests that antigen-antibody complexes may influence antigen processing by accessory cells and thereby T-cell reactivity.
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Affiliation(s)
- Gustavo Fenalti
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
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The lack of anti-idiotypic antibodies, not the presence of the corresponding autoantibodies to glutamate decarboxylase, defines type 1 diabetes. Proc Natl Acad Sci U S A 2008; 105:5471-6. [PMID: 18367670 DOI: 10.1073/pnas.0800578105] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Autoantibodies to glutamate decarboxylase 65 (GAD65Ab) are commonly believed to be a major characteristic for type 1 diabetes (T1D). We investigated the presence of GAD65Ab in healthy individuals (n = 238) and first-degree relatives (FDRs) of T1D patients (n = 27) who tested negative for GAD65Ab in conventional RIAs. Sera were applied to affinity columns coated with GAD65-specific mAbs to absorb anti-idiotypic antibodies (anti-Ids). The absorbed sera were analyzed for binding to GAD65 by RIAs. Both healthy individuals and FDRs present GAD65Ab that are inhibited by anti-Id, masking them in conventional detection methods. The presence of GAD65Ab-specific anti-Ids was confirmed by competitive ELISA. Remarkably, T1D patients (n = 54) and Stiff Person Syndrome patients (n = 8) show a specific lack of anti-Ids to disease-associated GAD65Ab epitopes. Purified anti-Ids from healthy individuals and FDRs inhibited the binding of GAD65Ab from T1D patients to GAD65. We conclude that masked GAD65Ab are present in the healthy population and that a lack of particular anti-Ids, rather than GAD65Ab per se, is a characteristic of T1D. The lack of these inhibitory antibodies may contribute to T cell activation by GAD65Ab.
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27
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Hall TR, Bogdani M, Leboeuf RC, Kirk EA, Maziarz M, Banga JP, Oak S, Pennington CA, Hampe CS. Modulation of diabetes in NOD mice by GAD65-specific monoclonal antibodies is epitope specific and accompanied by anti-idiotypic antibodies. Immunology 2007; 123:547-54. [PMID: 18005036 DOI: 10.1111/j.1365-2567.2007.02724.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Type 1 diabetes is caused by the autoimmune destruction of pancreatic beta cells. Here we show that administration of a human monoclonal antibody (b96.11) specific to the 65-kDa isoform of glutamate decarboxylase (GAD65) to prediabetic non-obese diabetic (NOD) mice significantly delays the onset of autoimmune diabetes. We found this effect to be epitope-specific, as only b96.11 showed this therapeutic property, while a GAD65-specific human monoclonal control antibody (b78) derived from the same patient, but specific to a different determinant of GAD65, had no significant effect on the progression of disease. Administration of b96.11 or b78 to NOD mice was accompanied by the generation of anti-idiotypic antibodies. Importantly, the induced anti-idiotypic antibodies were specific for the immunizing antibody and blocked the binding of GAD65 by the respective antibody. These findings suggest a potential role for the internal image of the GAD65 determinant recognized by b96.11 in the anti-idiotypic antibody, supporting an immunomodulatory role for GAD65-specific autoantibodies, as originally postulated by Jerne.
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Affiliation(s)
- Tyler R Hall
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
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28
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Shah P, Tramontano A, Makker SP. Intramolecular epitope spreading in Heymann nephritis. J Am Soc Nephrol 2007; 18:3060-6. [PMID: 18003776 DOI: 10.1681/asn.2007030342] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Immunization with megalin induces active Heymann nephritis, which reproduces features of human idiopathic membranous glomerulonephritis. Megalin is a complex immunological target with four discrete ligand-binding domains (LBDs) that may contain epitopes to which pathogenic autoantibodies are directed. Recently, a 236-residue N-terminal fragment, termed "L6," that spans the first LBD was shown to induce autoantibodies and severe disease. We used this model to examine epitope-specific contributions to pathogenesis. Sera obtained from rats 4 weeks after immunization with L6 demonstrated reactivity only with the L6 fragment on Western blot, whereas sera obtained after 8 weeks demonstrated reactivity with all four recombinant fragments of interest (L6 and LBDs II, III, and IV). We demonstrated that the L6 immunogen does not contain the epitopes responsible for the reactivity to the LBD fragments. Therefore, the appearance of antibodies directed at LBD fragments several weeks after the primary immune response suggests intramolecular epitope spreading. In vivo, we observed a temporal association between increased proteinuria and the appearance of antibodies to LBD fragments. These data implicate B cell epitope spreading in antibody-mediated pathogenesis of active Heymann nephritis, a model that should prove valuable for further study of autoimmune dysregulation.
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Affiliation(s)
- Pallavi Shah
- Department of Pediatrics, University of California, Davis, School of Medicine, Davis, California 95616, USA
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Maruyama T, Oak S, Hall TR, Banga JP, Ortqvist E, Ettinger RA, Endl J, Hampe CS. Autoantibody epitopes to the smaller isoform of glutamate decarboxylase do not differ in Swedish and Japanese type 1 diabetes patients and may be associated with high-risk human leucocyte antigen class II alleles. Clin Exp Immunol 2007; 150:416-21. [PMID: 17956579 DOI: 10.1111/j.1365-2249.2007.03527.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Type 1 diabetes (T1D) is an autoimmune disease with a strong human leucocyte antigen (HLA) class II association. Depending on geographic locations, the disease-associated HLA class II alleles vary. We evaluated the beta cell-specific autoimmunity reflected in autoantibodies directed to the smaller isoform of glutamate decarboxylase (GAD65) in Japanese and Swedish T1D patients. GAD65Ab epitope specificities were assessed using GAD65-specific recombinant Fab. GAD65Ab epitope specificities did not differ between Swedish and Japanese patients. Only recognition of the MICA-4-defined middle epitope was significantly stronger in the Japanese T1D patient group compared to the Swedish T1D patients (P = 0.001). Binding to the b96.11-defined middle epitope was substantial in both groups and showed significant associations with high-risk HLA class II haplotypes. In the Japanese T1D group the association was with haplotype DRB1*0802-DQB1*0302 (P = 0.0008), while in the Swedish T1D patients binding to the b96.11-defined epitope as associated with the presence of high-risk HLA genotypes DR3-DQB1*0201 and/or DR4-DQB1*0302 (P = 0.02). A significant association between reduction in binding in the presence of recombinant Fab (rFab) DPD and high-risk allele DQB1*0201 was found (P = 0.008) in the Swedish T1D patients only. We hypothesize that epitope-specific autoantibodies effect the peptide presentation on HLA class II molecules by modulating antigen uptake and processing. Molecular modelling of the high-risk HLA class II molecules will be necessary to test whether these different molecules present similar peptide-binding specificities.
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Affiliation(s)
- T Maruyama
- Department of Internal Medicine, Saitama Social Insurance Hospital, Saitama, Japan
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Hampe CS, Hall TR, Agren A, Rolandsson O. Longitudinal changes in epitope recognition of autoantibodies against glutamate decarboxylase 65 (GAD65Ab) in prediabetic adults developing diabetes. Clin Exp Immunol 2007; 148:72-8. [PMID: 17286757 PMCID: PMC1868852 DOI: 10.1111/j.1365-2249.2007.03334.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We analysed the beta cell-specific autoimmunity reflected in autoantibodies to the smaller isoform of glutamate decarboxylase (GAD65Ab) in the prediabetic period of GAD65Ab-positive healthy adults who developed Type 2 diabetes (T2D) during a follow-up period of 10 years. We found that of the adults that tested GAD65Ab-positive at baseline (n=25), six developed T2D and one developed Type 1 diabetes (T1D). Of the subjects that tested GAD65Ab-negative at baseline (n=2209), 81 developed T2D, one developed T1D and four developed unclassified diabetes, indicating that the risk for GAD65Ab-positive healthy adults to develop diabetes is increased sixfold. The GAD65Ab epitopes were characterized in a competition radioligand binding assay using recombinant Fab derived of GAD65-specific monoclonal antibodies. We observed that the GAD65Ab epitope specificities in the prediabetic period changed dynamically. Specifically, the binding to a middle and a C-terminal epitope increased during the follow-up period (P=0 x 03), causing a significant increase in the number of epitopes recognized (P=0 x 03). These findings are similar to previous observations of dynamic changes in the prediabetic period of schoolchildren at high risk for T1D development. However, the character of the epitopes differs between the two populations, suggesting differences in the beta cell-specific autoimmune response in the prediabetic period of patients with latent autoimmune diabetes in adults (LADA) and T1D.
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Affiliation(s)
- C S Hampe
- Department of Medicine, University of Washington, Seattle, WA, USA.
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Bekris LM, Jensen RA, Lagerquist E, Hall TR, Agardh CD, Cilio CM, Lethagen AL, Lernmark A, Robertson JA, Hampe CS. GAD65 autoantibody epitopes in adult patients with latent autoimmune diabetes following GAD65 vaccination. Diabet Med 2007; 24:521-6. [PMID: 17367313 DOI: 10.1111/j.1464-5491.2007.02091.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS Subcutaneous injection of recombinant human GAD65 (rhGAD65) in patients with latent autoimmune diabetes in adults (LADA) correlates with an increase in C-peptide levels. In this study we analysed the effect of rhGAD65 administration on the GAD65-specific autoimmune response. METHODS Longitudinal serum samples obtained from LADA patients (n = 47) who received 4, 20, 100 or 500 microg alum-formulated rhGAD65 or placebo by subcutaneous injection twice (4 weeks apart) were analysed for their epitope recognition using GAD65-specific recombinant Fab and GAD65/67 fusion proteins. RESULTS Overall, minor changes in the epitope pattern were observed using either approach. Only in the 500-microg dosage group was an increase in GAD65Ab level associated with a significant increase in the binding to a conformational epitope located at the middle part of GAD65. CONCLUSIONS Our data suggest that the apparent beneficial effects of 20 microg alum-formulated recombinant human GAD65 is not explained by changes in the GAD65Ab epitope pattern.
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Affiliation(s)
- L M Bekris
- Department of Medicine, University of Washington, Seattle, WA 98195, USA
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Moss CX, Tree TI, Watts C. Reconstruction of a pathway of antigen processing and class II MHC peptide capture. EMBO J 2007; 26:2137-47. [PMID: 17396153 PMCID: PMC1852786 DOI: 10.1038/sj.emboj.7601660] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Accepted: 02/26/2007] [Indexed: 11/10/2022] Open
Abstract
Endocytosed antigens are proteolytically processed and small amounts of peptides captured by class II MHC molecules. The details of antigen proteolysis, peptide capture and how destruction of T-cell epitopes is avoided are incompletely understood. Using the tetanus toxin antigen, we show that the introduction of 3-6 cleavage sites is sufficient to trigger a partially unfolded conformation able to bind to class II MHC molecules. The known locations of T-cell epitopes and protease cleavage sites predict that large domains of processed antigen (8-35 kDa) are captured under these conditions. Remarkably, when antigen is bound to the B-cell antigen receptor (BCR), processing can trigger a concerted 'hand-over' reaction whereby BCR-associated processed antigen is captured by neighbouring class II MHC molecules. Early capture of minimally processed antigen and confinement of the processing and class II MHC loading reaction to the membrane plane may improve the likelihood of T-cell epitope survival in the class II MHC pathway and may help explain the reciprocal relationships observed between B- and T-cell epitopes in many protein antigens and autoantigens.
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Affiliation(s)
- Catherine X Moss
- Division of Cell Biology & Immunology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Timothy I Tree
- Department of Immunobiology, King's College London, Guy's King's & St Thomas' School of Medicine, London, UK
| | - Colin Watts
- Division of Cell Biology & Immunology, School of Life Sciences, University of Dundee, Dundee, UK
- Division of Cell Biology and Immunology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK. Tel.: +44 1382 384233; Fax: +44 1382 385783; E-mail:
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Hampe CS, Nalini R, Maldonado MR, Hall TR, Garza G, Iyer D, Balasubramanyam A. Association of amino-terminal-specific antiglutamate decarboxylase (GAD65) autoantibodies with beta-cell functional reserve and a milder clinical phenotype in patients with GAD65 antibodies and ketosis-prone diabetes mellitus. J Clin Endocrinol Metab 2007; 92:462-7. [PMID: 17090641 DOI: 10.1210/jc.2006-1719] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT We previously characterized patients presenting with diabetic ketoacidosis prospectively into four subgroups of ketosis-prone diabetes mellitus (KPDM), based on the presence or absence of beta-cell autoimmunity (A+ or A-) and beta-cell functional reserve (B+ or B-). The A+B- KPDM subgroup comprises patients with classic, autoimmune type 1 diabetes, whereas the A+B+ KPDM subgroup has only partial beta-cell loss and a distinct clinical phenotype. OBJECTIVE We hypothesized that epitope specificity of autoantibodies directed against the 65-kDa isoform of glutamate decarboxylase (GAD65) reflects differences in beta-cell destruction. DESIGN Sera of sequential GAD65Ab-positive KPDM patients admitted for diabetic ketoacidosis (n = 36) were analyzed for their epitope recognition using five GAD65-specific recombinant Fab and their ability to inhibit GAD65 enzymatic activity. All patients were followed longitudinally to assess beta-cell functional reserve and insulin dependence. RESULTS Binding to an amino-terminal epitope defined by monoclonal antibody DPD correlated positively with fasting serum C-peptide levels at baseline (P = 0.0008) and after 1 yr (P = 0.007). Binding to the DPD-defined epitope also correlated positively with area under the curve for C-peptide after glucagon stimulation (P = 0.007) and with homeostasis model assessment percent B at 1 yr (P = 0.03). Binding to the DPD-defined epitope was significantly stronger in A+B+ than in A+B- patients (P = 0.001). Sera of 16 patients (44%) significantly inhibited GAD65 enzymatic activity, but this did not correlate with beta-cell function. CONCLUSION DPD-defined epitope specificity is correlated directly with preserved beta-cell functional reserve in GAD65Ab-positive patients and is associated with the milder clinical phenotype of A+B+ KPDM.
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Affiliation(s)
- Christiane S Hampe
- Robert H. Williams Laboratory, Department of Medicine, University of Washington, Seattle, Washington 98195, USA.
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Foreman AL, Van de Water J, Gougeon ML, Gershwin ME. B cells in autoimmune diseases: insights from analyses of immunoglobulin variable (Ig V) gene usage. Autoimmun Rev 2007; 6:387-401. [PMID: 17537385 PMCID: PMC2094701 DOI: 10.1016/j.autrev.2006.12.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2006] [Indexed: 12/11/2022]
Abstract
The role of B cells in autoimmune diseases has not been fully elucidated. It is also unclear whether breaking of B cell tolerance in patients with autoimmune diseases is due to underlying defects in the molecular mechanisms involved in the arrangement of antibody genes or deficiencies in the subsequent selective influences that shape the antibody repertoire. Analysis of immunoglobulin (Ig) variable (V) gene usage is beginning to provide answers to some of these questions. Such analyses have identified some differences in the basic Ig V gene repertoire of patients with autoimmune diseases compared to healthy controls, even though none of these differences can be considered major. Defects in positive and negative selection, mutational targeting and, in some cases, receptor editing have also been detected. In addition, analysis of Ig V gene usage in target organs and tissues of patients with autoimmune diseases has clearly demonstrated that there is a highly compartmentalized clonal expansion of B cells driven by a limited number of antigens in these tissues. Great progress has been made in the structural and functional characterization of disease-associated antibodies, largely because of the development of the combinatorial library technique. Use of antibodies generated by this technique offers great promise in identifying B cell epitopes on known target antigens and in gaining greater insights into the pathogenic role of B cells in both B and T cell mediated autoimmune diseases.
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Affiliation(s)
- Angela Lee Foreman
- Division of Rheumatology, Allergy and Clinical Immunology, University of California at Davis School of Medicine, Davis, CA 95616, USA.
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Kim HR, Kim EY, Cerny J, Moudgil KD. Antibody responses to mycobacterial and self heat shock protein 65 in autoimmune arthritis: epitope specificity and implication in pathogenesis. THE JOURNAL OF IMMUNOLOGY 2007; 177:6634-41. [PMID: 17082575 DOI: 10.4049/jimmunol.177.10.6634] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Many autoimmune diseases are believed to involve primarily T cell-mediated effector mechanisms. There is increasing realization, however, that Abs may also play a vital role in the propagation of T cell-driven disorders. In this study, on the rat adjuvant-induced arthritis (AA) model of human rheumatoid arthritis, we examined the characteristics of serum Ab response to mycobacterial heat shock protein (hsp) 65 (Bhsp65), self (rat) hsp65 (Rhsp65), and linear peptides spanning these two molecules. The AA-resistant WKY (RT.1(l)) rat responded to the heat-killed Mycobacterium tuberculosis immunization with a rapid burst of Abs to both Bhsp65 and Rhsp65. These Abs reacted with numerous peptide epitopes; however, this response was reduced to a few epitopes with time. On the contrary, the susceptible Lewis (RT.1(l)) rat developed a relatively lower Ab response to Bhsp65, and Abs to Rhsp65 did not appear until the recovery from the disease. The Ab response in Lewis rats diversified with progression of AA, and there was an intriguing overlap between the repertoire of Bhsp65-reactive B and T cells during the recovery phase of AA. Nonetheless, subsets of the repertoire of the late Abs in both rat strains became focused on the same epitope regions of Bhsp65 and Rhsp65. The functional relevance of these Abs was evident from the results showing that sera from recovery phase Lewis or WKY rats, but not that of naive rats, afforded protection against subsequent AA. These results are of significance in further understanding of the role of humoral immunity in the pathogenesis of autoimmune arthritis.
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Affiliation(s)
- Hong Ro Kim
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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36
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Djilali-Saiah I, Fakhfakh A, Louafi H, Caillat-Zucman S, Debray D, Alvarez F. HLA class II influences humoral autoimmunity in patients with type 2 autoimmune hepatitis. J Hepatol 2006; 45:844-50. [PMID: 17050030 DOI: 10.1016/j.jhep.2006.07.034] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 07/10/2006] [Accepted: 07/28/2006] [Indexed: 12/15/2022]
Abstract
BACKGROUND/AIMS Type 2 autoimmune hepatitis (AIH) is characterized by the presence of anti-liver kidney microsome (anti-LKM-1) and/or anti-liver cytosol type 1 (anti-LC1) autoantibodies. However, the correlation between these autoantibodies and the genetic background has not been studied. METHODS Frequencies of HLA class II alleles were compared between the 60 Caucasian children with type 2 AIH and 313 control subjects. The anti-LKM1 antibody reactivity directed against antigenic sites of CYP2D6 was analysed by ELISA. RESULTS HLA-DQB1 *0201 allele was found to be the primary genetic determinant of susceptibility to type 2 AIH by conferring the highest odd-ratio (OR = 6.4). HLA-DRB1 *03 allele was significantly increased (P < 0.0001) among patients with both anti-LKM1 and anti-LC1 autoantibodies as well as in those with only anti-LC1(+) compared to those with anti-LKM1(+) alone. In contrast, HLA-DRB1 *07 allele was significantly associated (P < 0.0001) with anti-LKM1(+) alone compared to groups with both anti-LKM and anti-LC1 or with LC1+ alone. Children with the DRB1 *07 allele develop anti-LKM1 autoantibodies having a more restricted specificity (2 epitopes) than to those having HLA-DRB1 *03 allele (5 epitopes). CONCLUSIONS The HLA-DR locus is involved in autoantibody expression, while the DQ locus appears to be a critical determinant for the development of type 2 AIH.
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Abstract
Human diabetes mellitus comprises two main clinical entities: type 1 and type 2 diabetes. While type 1 diabetes is autoimmune in origin, type 2 diabetes is due to a decreased sensitivity to insulin action (so-called insulin resistance) associated with impaired beta cell function. However, it is becoming increasingly clear that there is a certain overlap between these two diseases. While some degree of insulin resistance is present in type 1 diabetic patients, markers of beta cell autoimmunity (either primary or secondary) can frequently be detected in type 2 diabetic subjects. In this scenario, anti-CD38 autoantibodies (aAbs) have been described in both type 1 and type 2 diabetic patients. Contrary to the other known islet aAbs, anti-CD38 autoantibodies are more prevalent in long-standing than in new-onset type 1 diabetes, and more prevalent in type 2 than in type 1 diabetes. Moreover, anti-CD38 aAbs are endowed with unique stimulatory properties on Ca(2+) mobilization and insulin secretion. These observations suggest that autoimmunity may be both the cause and consequence of beta cell dysfunction, in either case imposing a further toll for the control of glucose homeostasis.
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Affiliation(s)
- Roberto Mallone
- INSERM U580, Institut Necker, U580-Batiment Sevres, 161 rue de Sèvres, 75015 Paris, France.
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Ichiki Y, Selmi C, Shimoda S, Ishibashi H, Gordon SC, Gershwin ME. Mitochondrial antigens as targets of cellular and humoral auto-immunity in primary biliary cirrhosis. Clin Rev Allergy Immunol 2006; 28:83-91. [PMID: 15879615 DOI: 10.1385/criai:28:2:083] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Several factors point toward an auto-immune pathogenesis for primary biliary cirrhosis(PBC), mostly based on the presence of serum auto-antibodies to mitochondrial antigens(AMAs) and autoreactive T cells (both helper and cytotoxic). Interestingly, epitopes recognized by AMA and T-cell clones are located within overlapping areas of the antigens. Moreover,a role for an imbalance in cytokine pattern and for natural-killer lymphocytes has also been proposed. Despite several experimental reports, no clear evidence is available regarding the interaction of these factors leading to bile duct destruction. This article reviews the current reports regarding the auto-immune reaction against mitochondrial auto-antigens in PBC.
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Affiliation(s)
- Yasunori Ichiki
- Division of Rheumatology, Allergy and Clinical Immunology, University of California at Davis School of Medicine, TB192, Davis, CA, USA
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Selmi C, Ichiki Y, Invernizzi P, Podda M, Gershwin ME. The enigma of primary biliary cirrhosis. Clin Rev Allergy Immunol 2006; 28:73-81. [PMID: 15879614 DOI: 10.1385/criai:28:2:073] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Primary biliary cirrhosis (PBC) is a chronic cholestatic disease characterized by a striking predominance in female patients (with most cases diagnosed between ages 40 and 60 yr) as well as serum auto-antibodies to mitochondrial antigens, elevated serum immunoglobulin M,progressive destruction of intrahepatic bile ducts, and, ultimately, liver cirrhosis and failure(1). The precise mechanisms leading to selective destruction of biliary epithelial cells lining intrahepatic bile ducts are still unknown, although numerous immunomediated pathways have been proposed. Genetic background appears to be important in determining susceptibility to the disease (2), but no clear association with alleles in the major histocompatibility complex has been identified. Molecular mimicry either by infections (3) or xenobiotics (4) has been proposed to be capable of breaking tolerance in genetically predisposed individuals, thus leading to onset of PBC. This article describes and discusses the available data regarding the immunomediated pathogenesis of PBC (with particular attention to auto-antibodies and autoreactive T-cells) and presents the recent evidence indicating a role for either xenobiotic chemicals or novel infectious agents in the induction of the disease.
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Affiliation(s)
- Carlo Selmi
- Division of Rheumatology, Allergy, and Clinical Immunology, University of California at Davis, Davis, CA, USA
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40
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Scealy M, Mackay IR, Rowley MJ. Amino acids critical for binding of autoantibody to an immunodominant conformational epitope of the pyruvate dehydrogenase complex subunit E2: Identification by phage display and site-directed mutagenesis. Mol Immunol 2006; 43:745-53. [PMID: 16360019 DOI: 10.1016/j.molimm.2005.03.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2004] [Indexed: 11/19/2022]
Abstract
The E2 subunit of the mitochondrial multienzyme pyruvate dehydrogenase complex (PDC-E2) is the major autoantigen in the liver disease, primary biliary cirrhosis (PBC). An epitope region which has been localized to amino acids 91-227 is believed to include the residue K173 to which is attached the lipoyl cofactor. We investigated structural features of this epitope region by screening random peptide phage-displayed libraries and identified prevalent phagotopes that contained likely contact amino acids in separate regions of the linear sequence, H132M133, and F178, V180. These were confirmed by site-directed alanine mutagenesis singly or in combination of the HM and FV residues in wild-type (wt) PDC-E2, and by immunization of rabbits with phage that expressed peptides MHLNTPP or FVLPWRI. The lipoyl lysine K173 also was mutated. Reactivities of mutants and wild-type (wt) PDC-E2, compared by ELISA using 12 PBC sera, showed decremental reactivity of mutant versus wt PDC-E2 (normalized to 100%): wt PDC-E2 (100%)>>PDC-E2(F178A,V180A) (mean+/-S.D., 59+/-17%)>PDC-E2(M133A) (50+/-13%)>PDC-E2(H132A) (36+/-13%)>PDC-E2(H132A,M133A) (28+/-8%)>PDC-E2(H132A,M133A,F178V,M180A) (18+/-13%). Notably PDC-E2(K173A) retained full reactivity (93+/-21%). Rabbits immunized with phage peptides generated antibodies reactive with entire PDC-E2. Our data convincingly validate phage library technology for defining spatially disparate contact residues for conformational epitopes. Ensuing data could be generally applicable to search for occult extrinsic agents as initiators of autoimmunity.
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Affiliation(s)
- Marita Scealy
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Rd, Clayton, Vic. 3800, Australia
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Raju R, Foote J, Banga JP, Hall TR, Padoa CJ, Dalakas MC, Ortqvist E, Hampe CS. Analysis of GAD65 autoantibodies in Stiff-Person syndrome patients. THE JOURNAL OF IMMUNOLOGY 2006; 175:7755-62. [PMID: 16301686 DOI: 10.4049/jimmunol.175.11.7755] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Autoantibodies to the 65-kDa isoform of glutamate decarboxylase GAD65 (GAD65Ab) are strong candidates for a pathological role in Stiff-Person syndrome (SPS). We have analyzed the binding specificity of the GAD65Ab in serum and cerebrospinal fluid (CSF) of 12 patients with SPS by competitive displacement studies with GAD65-specific rFab-derived from a number of human and mouse mAbs specific for different determinants on the Ag. We demonstrate considerable differences in the epitope specificity when comparing paired serum and CSF samples, suggesting local stimulation of B cells in the CSF compartment of these patients. Moreover, these autoantibodies strongly inhibit the enzymatic activity of GAD65, thus blocking the formation of the neurotransmitter gamma-aminobutyric acid. The capacity of the sera to inhibit the enzymatic activity of GAD65 correlated with their binding to a conformational C-terminal Ab epitope. Investigation of the inhibitory mechanism revealed that the inhibition could not be overcome by high concentrations of glutamate or the cofactor pyridoxal phosphate, suggesting a noncompetitive inhibitory mechanism. Finally, we identified a linear epitope on amino acids residues 4-22 of GAD65 that was recognized solely by autoantibodies from patients with SPS but not by serum from type 1 diabetes patients. A mAb (N-GAD65 mAb) recognizing this N-terminal epitope was successfully humanized to enhance its potential therapeutic value by reducing its overall immunogenicity.
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Affiliation(s)
- Raghavanpillai Raju
- Neuromuscular Diseases Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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Abstract
Autoantibodies have been used as good markers for the prediction of future development of type 1 diabetes mellitus (T1DM), but are not thought to be pathogenic in this disease. The role of B cells that produce autoantibodies in the pathogenesis of human T1DM is largely unknown. In the non-obese diabetic (NOD) mouse model of autoimmune diabetes, it has been shown that B cells may contribute multifariously to the pathogenesis of the disease. Some aspects of deficiencies of B cell tolerance may lead to the circulation of autoreactive B cells. In addition, the antigen-presenting function of autoantigen specific B cells is likely to be particularly important, and autoantibodies are also considered to play a critical role. This review discusses the possible aspects of B cells involved in the development of autoimmune diabetes.
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Affiliation(s)
- F Susan Wong
- Department of Cellular and Molecular Medicine, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom.
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Padoa CJ, Crowther NJ, Thomas JW, Hall TR, Bekris LM, Torn C, Landin-Olsson M, Ortqvist E, Palmer JP, Lernmark A, Hampe CS. Epitope analysis of insulin autoantibodies using recombinant Fab. Clin Exp Immunol 2005; 140:564-71. [PMID: 15932520 PMCID: PMC1809383 DOI: 10.1111/j.1365-2249.2005.02802.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Autoantibodies to insulin are often the first autoantibodies detected in young children with type 1 diabetes and can be present before the onset of clinical diabetes. These autoantibodies and their epitopes are, however, not well characterized. We explored the use of monoclonal antibodies and their recombinant Fab as reagents for epitope analysis. In this study we cloned and characterized the recombinant Fab of the insulin-specific monoclonal antibody CG7C7. We found the epitope of this antibody to be located predominantly at the A-chain loop of the insulin molecule. The recombinant Fab was then used to compete for insulin binding against insulin autoantibodies present in sera from patients with type 1 or type 1.5 diabetes. In competition experiments with sera positive for autoantibodies to insulin the recombinant Fab significantly reduced the binding to [125I]-insulin by sera of type 1 (n = 35) and type 1.5 diabetes [latent autoimmune diabetes in adults (LADA)] (n = 14) patients (P < 0.0001). We conclude that competition between insulin-specific monoclonal antibodies or their recombinant Fab and insulin autoantibodies should prove useful in the epitope analysis of autoantibodies to insulin.
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Affiliation(s)
- C J Padoa
- Department of Chemical Pathology, University of the Witwatersrand and National Health Laboratory Service, Johannesburg, South Africa
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Schlosser M, Banga JP, Madec AM, Binder KA, Strebelow M, Rjasanowski I, Wassmuth R, Gilliam LK, Luo D, Hampe CS. Dynamic changes of GAD65 autoantibody epitope specificities in individuals at risk of developing type 1 diabetes. Diabetologia 2005; 48:922-30. [PMID: 15834701 DOI: 10.1007/s00125-005-1719-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2004] [Accepted: 12/21/2004] [Indexed: 10/25/2022]
Abstract
AIMS/HYPOTHESIS Progression to type 1 diabetes is associated with intramolecular epitope spreading to disease-specific antibody epitopes located in the middle region of glutamic acid decarboxylase 65 (GAD65). METHODS The relationship between intramolecular epitope spreading of autoantibodies specific to GAD65 in relation to the risk of developing type 1 diabetes was tested in 22 high-risk individuals and 38 low-risk individuals. We determined the conformational epitopes in this longitudinal study by means of competition experiments using recombinant Fab of four GAD65-specific monoclonal antibodies. RESULTS Sera from high-risk children in the preclinical stage recognise a specific combination of GAD65 antibody epitopes located in the middle and the C-terminus of GAD65. High risk of progressing to disease is associated with the emergence of antibodies specific for conformational epitopes at the N-terminus and the middle region. Binding to already established antibody epitopes located in the middle and at the N-terminus increases and shows a significant relation (p=0.005) with HLA, which confers risk of developing diabetes. CONCLUSIONS/INTERPRETATION In type 1 diabetes, GAD65 antibodies are initially generated against the middle and C-terminal regions of GAD65. In genetically predisposed subjects the autoimmune response may then undergo intramolecular epitope spreading towards epitopes on the N-terminus and further epitopes located in the middle. These findings clearly demonstrate that the GAD65 autoantibody response in the preclinical stage of type 1 diabetes is dynamic and related to the HLA genotypes that confer risk of diabetes. GAD65-specific Fab should prove useful in predicting progression from islet autoimmunity to clinical onset of type 1 diabetes.
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Affiliation(s)
- M Schlosser
- Institute of Pathophysiology, Ernst Moritz Arndt University of Greifswald, Karlsburg, Germany
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Abstract
The conversion of exogenous and endogenous proteins into immunogenic peptides recognized by T lymphocytes involves a series of proteolytic and other enzymatic events culminating in the formation of peptides bound to MHC class I or class II molecules. Although the biochemistry of these events has been studied in detail, only in the past few years has similar information begun to emerge describing the cellular context in which these events take place. This review thus concentrates on the properties of antigen-presenting cells, especially those aspects of their overall organization, regulation, and intracellular transport that both facilitate and modulate the processing of protein antigens. Emphasis is placed on dendritic cells and the specializations that help account for their marked efficiency at antigen processing and presentation both in vitro and, importantly, in vivo. How dendritic cells handle antigens is likely to be as important a determinant of immunogenicity and tolerance as is the nature of the antigens themselves.
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Affiliation(s)
- E Sergio Trombetta
- Department of Cell Biology and Section of Immunobiology, Ludwig Institute for Cancer Research, Yale University School of Medicine, New Haven, Connecticut 06520-8002, USA.
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Ichiki Y, Aoki CA, Bowlus CL, Shimoda S, Ishibashi H, Gershwin ME. T cell immunity in autoimmune hepatitis. Autoimmun Rev 2005; 4:315-21. [PMID: 15990080 DOI: 10.1016/j.autrev.2005.01.005] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2004] [Accepted: 01/11/2005] [Indexed: 12/16/2022]
Abstract
T cells play a central role in the immunopathogenesis of AIH. Until recently CD4+ T cells were thought to be critical for disease development, increasing evidence has shown that CD8+ T and gammadelta T cells also play a significant role. The predisposition of certain HLA genotypes to AIH as well as the clonal expansion of a limited number of T cell receptors suggests that the presentation of a self-antigen or a molecular mimic may be responsible for the initiation of the immune response. Given the association of AIH with viral hepatitis, it is thought that the loss of tolerance begins with an infection of hepatocytes and subsequent cytolysis by CD8+ T cells. The presentation of self-antigens or molecular mimics leads to activation and clonal expansion of T cells; this process may be increased by impaired regulatory T cells and a defect in apoptosis. Ultimately T cells initiate B cell production of autoantibodies, proinflammatory cytokines and finally hepatocyte cytotoxicity.
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Affiliation(s)
- Yasunori Ichiki
- Division of Rheumatology, Allergy and Clinical Immunology, University of California at Davis School of Medicine, TB192, One Shields Avenue, Davis, CA 95616, USA
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Gilliam LK, Binder KA, Banga JP, Madec AM, Ortqvist E, Kockum I, Luo D, Hampe CS. Multiplicity of the antibody response to GAD65 in Type I diabetes. Clin Exp Immunol 2004; 138:337-41. [PMID: 15498046 PMCID: PMC1809224 DOI: 10.1111/j.1365-2249.2004.02610.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Type I diabetes (TID) is an autoimmune disease characterized in part by the presence of autoantibodies directed against glutamic acid decarboxylase 65 (GAD65), among other pancreatic islet antigens. We investigated the independent epitope specificities of these GAD65 antibodies (GAD65Ab) and their combinations in the sera of new onset TID patients and first-degree relatives positive for GAD65Ab. For our analysis, we used four GAD65-specific recombinant Fabs (rFabs) that recognize different conformational determinants of GAD65 located throughout the molecule, including the N-terminal, the middle and the C-terminal regions. We used these epitope-specific rFabs in competition assays to determine the binding specificity of the autoantibodies found in patient sera. Among the 61 sera from newly diagnosed GAD65Ab-positive TID patients GAD65 binding was competed for 23 sera by all four rFabs, 29 by at least two rFabs, and in nine sera were displaced by one or no rFab. In contrast, none of the 24 sera from GAD65Ab-positive first-degree relatives of TID patients were displaced by all four rFabs. When using all four rFabs simultaneously to compete with GAD65Ab binding, binding of sera from TID patients was reduced by an average of 70%. A significantly weaker competition was observed when evaluating sera of GAD65Ab-positive first-degree relatives (P < 0.0001).
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Affiliation(s)
- L K Gilliam
- Robert H. Williams Laboratory, Department of Medicine, University of Washington, Seattle, Washington 98195, USA
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Wong FS, Wen L, Tang M, Ramanathan M, Visintin I, Daugherty J, Hannum LG, Janeway CA, Shlomchik MJ. Investigation of the role of B-cells in type 1 diabetes in the NOD mouse. Diabetes 2004; 53:2581-7. [PMID: 15448087 DOI: 10.2337/diabetes.53.10.2581] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
B-cells are important in the development of type 1 diabetes, but their role is not completely defined. Although B-cells produce autoantibodies, these are not thought to be pathogenic; however, their antigen-presenting function is postulated to be critical. To examine the relative importance of these functions of B-cells, we have generated nonobese diabetic (NOD) B-cell-deficient mice that express a transgene encoding a mutant heavy chain immunoglobulin transgene on the cell surface but cannot secrete immunoglobulins (mIgs). This allowed us to dissect the importance of the relative roles of antigen presentation, dissociated from antibody production. We found that the expression of the mIg transgene increased insulitis and the incidence of diabetes compared with transgene-negative NOD B-cell-deficient mice, indicating that the ability to produce antibodies is not necessary for B-cells to have some effect on the development of diabetes. However, diabetes was not restored to the level seen in normal NOD mice. This may relate to reduced ability to activate an islet-specific T-cell repertoire, presumably due to the reduced islet-specific B-cell repertoire. Our results implicate a specific antigen-presenting function for B-cells.
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Affiliation(s)
- F Susan Wong
- Department of Pathology and Microbiology, University of Bristol, University Walk, Bristol BS8 1TD, UK.
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Wulff H, Knaus HG, Pennington M, Chandy KG. K+ channel expression during B cell differentiation: implications for immunomodulation and autoimmunity. THE JOURNAL OF IMMUNOLOGY 2004; 173:776-86. [PMID: 15240664 DOI: 10.4049/jimmunol.173.2.776] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Using whole-cell patch-clamp, fluorescence microscopy and flow cytometry, we demonstrate a switch in potassium channel expression during differentiation of human B cells from naive to memory cells. Naive and IgD(+)CD27(+) memory B cells express small numbers of the voltage-gated Kv1.3 and the Ca(2+)-activated intermediate-conductance IKCa1 channel when quiescent, and increase IKCa1 expression 45-fold upon activation with no change in Kv1.3 levels. In contrast, quiescent class-switched memory B cells express high levels of Kv1.3 ( approximately 2000 channels/cell) and maintain their Kv1.3(high) expression after activation. Consistent with their channel phenotypes, proliferation of naive and IgD(+)CD27(+) memory B cells is suppressed by the specific IKCa1 inhibitor TRAM-34 but not by the potent Kv1.3 blocker Stichodactyla helianthus toxin, whereas the proliferation of class-switched memory B cells is suppressed by Stichodactyla helianthus toxin but not TRAM-34. These changes parallel those reported for T cells. Therefore, specific Kv1.3 and IKCa1 inhibitors may have use in therapeutic manipulation of selective lymphocyte subsets in immunological disorders.
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Affiliation(s)
- Heike Wulff
- Department of Medical Pharmacology and Toxicology, University of California, Davis, CA 95616, USA.
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Guo J, Pichurin PN, Morris JC, Rapoport B, McLachlan SM. Naked deoxyribonucleic acid vaccination induces recognition of diverse thyroid peroxidase T cell epitopes. Endocrinology 2004; 145:3671-8. [PMID: 15123538 DOI: 10.1210/en.2004-0303] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recently, we observed that vaccination of BALB/c mice with thyroid peroxidase (TPO)-DNA in a plasmid is highly effective at inducing antibodies that interact with the immunodominant region recognized by human autoantibodies. We have now analyzed the TPO epitopes recognized by memory T cells in these animals. Splenocytes from TPO-DNA (not control DNA)-vaccinated mice responded to TPO protein antigen, as measured by interferon-gamma production. As a group, TPO-immunized mice recognized 35 of 55 overlapping synthetic peptides that encompass the 814-amino acid TPO ectodomain. In individual mice, between five and 10 peptides induced splenocyte responses. Two T cell epitopes were immunodominant, one of which is also recognized by patients with autoimmune thyroid disease. To explore a potential correlation between T and B cell epitopes, we analyzed serum TPO antibody epitopic fingerprints. No relationship was evident. However, the number of T cell epitopes recognized by individual mice was inversely proportional to recognition of an antibody epitopic subdomain. The diversity of TPO T cell epitopes is in striking contrast to the restricted number of TSH receptor (TSHR) peptides (four of 29) recognized by T cells, as is the paucity of antibodies in the same strain of mice vaccinated with TSHR-DNA. In conclusion, our data highlight differences for both antibody and T cell epitopic recognition in TPO- vs. TSHR-DNA-immunized BALB/c mice. These findings provide insight into mechanisms that may be involved in spontaneous immune responses to two major thyroid autoantigens in humans.
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Affiliation(s)
- Jin Guo
- Cedars-Sinai Medical Center, University of California School of Medicine, Los Angeles, Californoia 90048, USA
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