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Kyllesbech C, Trier N, Mughal F, Hansen P, Holmström M, El Fassi D, Hasselbalch H, Skov V, Kjær L, Andersen M, Ciplys E, Slibinskas R, Frederiksen J, Højrup P, Houen G. Antibodies to calnexin and mutated calreticulin are common in human sera. Curr Res Transl Med 2023; 71:103380. [PMID: 36738659 DOI: 10.1016/j.retram.2023.103380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 01/12/2023] [Accepted: 01/24/2023] [Indexed: 01/30/2023]
Abstract
PURPOSE OF THE STUDY Calreticulin is an endoplasmic reticulum chaperone protein, which is involved in protein folding and in peptide loading of major histocompatibility complex class I molecules together with its homolog calnexin. Mutated calreticulin is associated with a group of hemopoietic disorders, especially myeloproliferative neoplasms. Currently only the cellular immune response to mutated calreticulin has been described, although preliminary findings have indicated that antibodies to mutated calreticulin are not specific for myeloproliferative disorders. These findings have prompted us to characterize the humoral immune response to mutated calreticulin and its chaperone homologue calnexin. PATIENTS AND METHODS We analyzed sera from myeloproliferative neoplasm patients, healthy donors and relapsing-remitting multiple sclerosis patients for the occurrence of autoantibodies to wild type and mutated calreticulin forms and to calnexin by enzyme-linked immunosorbent assay. RESULTS Antibodies to mutated calreticulin and calnexin were present at similar levels in serum samples of myeloproliferative neoplasm and multiple sclerosis patients as well as healthy donors. Moreover, a high correlation between antibodies to mutated calreticulin and calnexin was seen for all patient and control groups. Epitope binding studies indicated that cross-reactive antibodies bound to a three-dimensional epitope encompassing a short linear sequence in the C-terminal of mutated calreticulin and calnexin. CONCLUSION Collectively, these findings indicate that calreticulin mutations may be common and not necessarily lead to onset of myeloproliferative neoplasm, possibly due to elimination of cells with mutations. This, in turn, may suggest that additional molecular changes may be required for development of myeloproliferative neoplasm.
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Affiliation(s)
- C Kyllesbech
- Department of Neurology, Valdemar Hansens vej 23, Rigshospitalet, Glostrup, Denmark; Institute of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, Odense M, Denmark
| | - N Trier
- Department of Neurology, Valdemar Hansens vej 23, Rigshospitalet, Glostrup, Denmark
| | - F Mughal
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, Copenhagen Ø, Denmark
| | - P Hansen
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, Copenhagen Ø, Denmark
| | - M Holmström
- National Center for Cancer Immune Therapy (CCIT-DK), Department of Oncology, Borgmester Ib Juuls Vej 25C, Copenhagen University Hospital, Herlev, Denmark; Department of Immunology and Microbiology, University of Copenhagen, Blegdamsvej 3B, Copenhagen, Denmark
| | - D El Fassi
- Department of Hematology, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, Copenhagen, Denmark; Department of Clinical Medicine, University of Copenhagen, Blegdamsvej 3B, Copenhagen N, Denmark
| | - H Hasselbalch
- Department of Hematology, Zealand University Hospital Roskilde, Sygehusvej 10, Roskilde, Denmark
| | - V Skov
- Department of Hematology, Zealand University Hospital Roskilde, Sygehusvej 10, Roskilde, Denmark
| | - L Kjær
- Department of Hematology, Zealand University Hospital Roskilde, Sygehusvej 10, Roskilde, Denmark
| | - M Andersen
- Department of Immunology and Microbiology, University of Copenhagen, Blegdamsvej 3B, Copenhagen, Denmark
| | - E Ciplys
- Institute of Biotechnology, University of Vilnius, Sauletékio al. 7, Vilnius, Lithuania
| | - R Slibinskas
- Institute of Biotechnology, University of Vilnius, Sauletékio al. 7, Vilnius, Lithuania
| | - J Frederiksen
- Department of Neurology, Valdemar Hansens vej 23, Rigshospitalet, Glostrup, Denmark
| | - P Højrup
- Institute of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, Odense M, Denmark
| | - G Houen
- Department of Neurology, Valdemar Hansens vej 23, Rigshospitalet, Glostrup, Denmark; Institute of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, Odense M, Denmark.
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Chan EKL. Anti-Ro52 Autoantibody Is Common in Systemic Autoimmune Rheumatic Diseases and Correlating with Worse Outcome when Associated with interstitial lung disease in Systemic Sclerosis and Autoimmune Myositis. Clin Rev Allergy Immunol 2022; 63:178-193. [PMID: 35040083 DOI: 10.1007/s12016-021-08911-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/29/2021] [Indexed: 01/13/2023]
Abstract
This review highlights the 30 plus years research progress since the discovery of autoantibody to Ro52/TRIM21 in patients with systemic lupus erythematosus (SLE) and Sjögren's syndrome (SjS). After the initial expression cloning of the Ro52 cDNA, it has taken many years to the current understanding in the interesting biological function of Ro52 as an E3 ubiquitin ligase and its role in innate immune clearance of intracellular IgG-bound complex. Early observations show that anti-Ro52, mostly associated with anti-SS-A/Ro60 and/or anti-SS-B/La, is commonly found in SLE (40-70%), SjS (70-90%), neonatal lupus erythematosus (NLE, 75-90%), and subacute cutaneous lupus erythematosus (50-60%). Anti-Ro52 has long been postulated to play a direct pathogenic role in congenital heart block in NLE as well as in the QT interval prolongation in some adults. The widespread availability of the anti-Ro52 assay has led to the detection of anti-Ro52 in other diseases including autoimmune hepatitis (20-40%), systemic sclerosis (10-30%), and autoimmune myositis (20-40%). More than ten studies have pointed to an association of anti-Ro52 with interstitial lung disease and, more importantly, correlating with poor outcome and worse survival. Other studies are implicating an interesting role for anti-Ro52 in the diagnosis of certain cancers. Future studies are needed to examine the mechanism in the pathogenesis of anti-Ro52 and carefully documenting its causal relationships in different disease conditions.
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Affiliation(s)
- Edward K L Chan
- Department of Oral Biology, University of Florida, 1395 Center Drive, Gainesville, FL, 32610-0424, USA.
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Gkoutzourelas A, Liaskos C, Mytilinaiou MG, Simopoulou T, Katsiari C, Tsirogianni A, Daoussis D, Scheper T, Meyer W, Bogdanos DP, Sakkas LI. Anti-Ro60 Seropositivity Determines Anti-Ro52 Epitope Mapping in Patients With Systemic Sclerosis. Front Immunol 2018; 9:2835. [PMID: 30581434 PMCID: PMC6293197 DOI: 10.3389/fimmu.2018.02835] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 11/16/2018] [Indexed: 12/14/2022] Open
Abstract
Epitope mapping of anti-Ro52 antibodies (Abs) has been extensively studied in patients with Sjögren's syndrome (SjS) and systemic lupus erythematosus (SLE). Comprehensive epitope mapping in systemic sclerosis (SSc), where anti-Ro52 antibodies are also frequently detected, has not been performed. The aim of the present study was to fully characterize Ro52 epitopes in anti-Ro52-positive SSc using Ro52 fragments spanning the full antigen. Further analysis was made according to anti-Ro60 status. Epitope mapping was performed in 43 anti-Ro52-positive SSc patients. Seventy eight anti-Ro52-positive pathological controls, including 20 patients with SjS, 28 patients with SLE, 15 patients with dermatomyositis (DM), and 15 patients with primary biliary cholangitis (PBC), and 20 anti-Ro52-negative healthy individuals as normal controls were also tested. Five recombinant Ro52 fragments [Ro52-1 (aa 1-127), Ro52-2 (aa 125-268), Ro52-3 (aa 268-475), Ro52-4 (aa 57-180), and Ro52-5 (aa 181-320) were used to test reactivity by line-immunoassay and in house ELISA. Anti-Ro60 reactivity was tested by ELISA. All anti-Ro52 positive sera reacted with Ro52-2; none recognized Ro52-3. Antibodies against Ro52-1 were less frequently found in SSc than in SjS/SLE (11.6 vs. 41.7%, p = 0.001); and antibodies against Ro52-4 were less frequently found in SSc than in SjS/SLE (27.9 vs. 50%, p = 0.03). In SSc patients, reactivity against Ro52-1 was more frequent in anti-Ro52+/anti-Ro60+ than in anti-Ro52+/anti-Ro60-patients (33.3 vs. 0%, p = 0.003). In this comprehensive analysis of Ro52 epitope mapping in SSc, the coiled coil domain remains the predominant epitope on Ro52. Contrary to SjS and SLE, patients with SSc fail to identify epitopic regions within the N-terminus of the protein, especially if they lack con-current anti-Ro60 reactivity.
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Affiliation(s)
- Athanasios Gkoutzourelas
- Department of Rheumatology and Clinical Immunology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
| | - Christos Liaskos
- Department of Rheumatology and Clinical Immunology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
| | - Maria G. Mytilinaiou
- Department of Rheumatology and Clinical Immunology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
| | - Theodora Simopoulou
- Department of Rheumatology and Clinical Immunology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
| | - Christina Katsiari
- Department of Rheumatology and Clinical Immunology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
| | - Alexandra Tsirogianni
- Department of Immunology-Histocompatibility, Evangelismos General Hospital, Athens, Greece
| | - Dimitrios Daoussis
- Department of Rheumatology, Patras University Hospital, Faculty of Medicine, University of Patras Medical School, Patras, Greece
| | - Thomas Scheper
- Institute of Immunology Affiliated to Euroimmun AG, Lübeck, Germany
| | - Wolfgang Meyer
- Institute of Immunology Affiliated to Euroimmun AG, Lübeck, Germany
| | - Dimitrios P. Bogdanos
- Department of Rheumatology and Clinical Immunology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
| | - Lazaros I. Sakkas
- Department of Rheumatology and Clinical Immunology, Faculty of Medicine, School of Health Sciences, University of Thessaly, Larissa, Greece
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Sontheimer RD. James Neil Gilliam, MD-the career arc of a patient-oriented translational clinical investigation changemaker in rheumatologic skin disease. ANNALS OF TRANSLATIONAL MEDICINE 2018; 6:217. [PMID: 30023380 DOI: 10.21037/atm.2018.05.20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
James Neil Gilliam, MD, was an American academic physician who was trained in internal medicine, dermatology, dermatopathology and rheumatology. This "quadruple-threat" profile of postgraduate medical training provided him with a rather unique perspective on genetically-complex, environmentally-impacted human autoimmune disorders such as lupus erythematosus (LE). Both the skin and vital internal organs can be damaged by LE autoimmunity. And, LE is clinically-expressed quite variably from one individual to another making prognosis difficult. As such it can be very challenging to know what the optimal treatment approach might be for new patients presenting with this potentially-fatal disorder. Dr. Gilliam's major career focus was to better understand the complex relationships that exist between the clinical expression of LE in the skin and vital internal organs. In the late 1970s, Dr. Gilliam first described a new clinical form of LE skin disease that he designated as "subacute cutaneous LE." Subacute cutaneous LE would subsequently serve as the linchpin for a new classification scheme for LE skin disease that would later become known as the "Gilliam classification" of LE skin disease. In addition, he was among the first to apply modern immunologic insight to the classification of cutaneous LE. This work was carried out in the Divisions of Dermatology and Rheumatology and the Department of Dermatology at the University of Texas Southwestern Medical School in Dallas, Texas (UT Southwestern) starting in 1972. Dr. Gilliam served as the Founding Chairman of the Department of Dermatology at UT Southwestern in 1982, 2 years before his untimely death. Dr. Gilliam's clinical research accomplishments were matched by his ability to identify and encourage like-minded young people. A high percentage of his trainees went on to successful academic research careers and leadership positions in American Dermatology. Dr. Gilliam's untimely death from cancer deprived several generations of dermatologists and rheumatologists the benefit of his warm support and insightful guidance. In addition, American Dermatology and Rheumatology leadership organizations were deprived of his strong leadership skills.
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Affiliation(s)
- Richard D Sontheimer
- Department of Dermatology, University of Utah School of Medicine, Salt Lake City, Utah, USA
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Barrera MJ, Aguilera S, Castro I, González S, Carvajal P, Molina C, Hermoso MA, González MJ. Endoplasmic reticulum stress in autoimmune diseases: Can altered protein quality control and/or unfolded protein response contribute to autoimmunity? A critical review on Sjögren's syndrome. Autoimmun Rev 2018; 17:796-808. [PMID: 29890347 DOI: 10.1016/j.autrev.2018.02.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 02/13/2018] [Indexed: 12/11/2022]
Abstract
For many years, researchers in the field of autoimmunity have focused on the role of the immune components in the etiopathogenesis of autoimmune diseases. However, some studies have demonstrated the importance of target tissues in their pathogenesis and the breach of immune tolerance. The immune system as well as target tissue cells (plasmatic, β-pancreatic, fibroblast-like synoviocytes, thyroid follicular and epithelial cells of the lachrymal glands, salivary glands, intestine, bronchioles and renal tubules) share the characteristic of secretory cells with an extended endoplasmic reticulum (ER). The function of these cells depends considerably on a normal ER function and calcium homeostasis, so they can produce and secrete their main components, which include glycoproteins involved in antigenic presentation such as major histocompatibility complex (MHC) class I and II. All these proteins are synthesized and modified in the ER, and for this reason disturbances in the normal functions of this organelle such as protein folding, protein quality control, calcium homeostasis and redox balance, promote accumulation of unfolded or misfolded proteins, a condition known as ER stress. Autoimmune diseases are characterized by inflammation, which has been associated with an ER stress condition. Interestingly, patients with these diseases contain circulating auto-antibodies against chaperone proteins (such as Calnexin and GRP94), thus affecting the folding and assembly of MHC class I and II glycoproteins and their loading with peptide. The main purpose of this article is to review the involvement of the protein quality control and unfolded protein response (UPR) in the ER protein homeostasis (proteostasis) and their alterations in autoimmune diseases. In addition, we describe the interaction between ER stress and inflammation and evidences are shown of how autoimmune diseases are associated with an ER stress condition, with a special emphasis on the second most prevalent autoimmune rheumatic disease, Sjögren's syndrome.
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Affiliation(s)
- María-José Barrera
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Sergio Aguilera
- Departamento de Reumatología, Clínica INDISA, Santiago, Chile
| | - Isabel Castro
- Departamento de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Sergio González
- Escuela de Odontología, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Patricia Carvajal
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Claudio Molina
- Escuela de Postgrado, Facultad de Odontología, Universidad San Sebastián, Santiago, Chile
| | - Marcela A Hermoso
- Programa de Inmunología, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - María-Julieta González
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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Wang Y, Xie J, Liu Z, Fu H, Huo Q, Gu Y, Liu Y. Association of calreticulin expression with disease activity and organ damage in systemic lupus erythematosus patients. Exp Ther Med 2017; 13:2577-2583. [PMID: 28565882 DOI: 10.3892/etm.2017.4235] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/26/2017] [Indexed: 11/06/2022] Open
Abstract
Measurement of disease activity in patients with systemic lupus erythematosus (SLE) is important for monitoring disease progression and evaluating the therapeutic effects. The severity of organ damage correlates with clinical status and prognosis. Therefore, it is imperative to find an effective biomarker measuring disease activity and organ damage for SLE management. The present study investigated the possibility of serum calreticulin (CRT) in the assessment of disease activity and organ damage in SLE patients. Serum CRT levels from 80 patients with SLE, 55 patients with other autoimmune diseases and 60 healthy controls (HC) were measured by ELISA. Disease activity was assessed using the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) scores. Organ damage was evaluated with the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index. CRT levels in SLE were significantly higher than that in other autoimmune diseases and HC. CRT was correlated with SLEDAI-2K score (r=0.3345, P=0.0024), and with anti-double-stranded DNA (anti-dsDNA) (r=0.4483, P<0.0001). A significant negative correlation of CRT levels with complement 3 (r=-0.3635, P=0.0009) and complement 4 (r=-0.3507, P=0.0014) was observed in patients with SLE. Furthermore, the patients with SLE and a positive anti-Ro52 result had higher levels of CRT compared with those with a negative anti-Ro52 result (P<0.001). Elevated levels of CRT were also reported among patients with SLE who also indicated the presence of cumulative organ damage. In addition, increased expression of CRT correlated with the presence of lupus nephritis. In conclusion, the results of the current report provided that CRT may be used as a potential biomarker for clinical diagnosis and of prognosis, providing additional information regarding disease activity and organ damage alongside other traditional indices.
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Affiliation(s)
- Yichao Wang
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Jiaogui Xie
- Department of Hepatobiliary Surgery, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi 710032, P.R. China.,Department of Urology, The Fifteenth Military Hospital of China, Wusu, Xinjiang 833000, P.R. China
| | - Zhili Liu
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Hongwei Fu
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China.,Department of Clinical Laboratory Medicine, Tianjin Medical University General Hospital, Tianjin 300050, P.R. China
| | - Qianyu Huo
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Yajun Gu
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China
| | - Yunde Liu
- School of Medical Laboratory, Tianjin Medical University, Tianjin 300070, P.R. China
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Reed JH, Dudek NL, Osborne SE, Kaufman KM, Jackson MW, Purcell AW, Gordon TP. Reactivity with dichotomous determinants of Ro 60 stratifies autoantibody responses in lupus and primary Sjögren's syndrome. ACTA ACUST UNITED AC 2010; 62:1448-56. [PMID: 20131295 DOI: 10.1002/art.27370] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Analysis of B cell determinants of Ro 60 exposed on the surface of apoptotic cells (apotopes) or intracellular epitopes provides insight into the structural forms of the autoantigen that break immune tolerance. This study was initiated to compare anti-Ro 60 responses in systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (SS) against membrane-bound and intracellular forms of Ro 60. METHODS The reactivity of autoantibodies from patients with SLE and primary SS to Ro 60 apotopes and epitopes was assessed by multiparameter flow cytometry and solid-phase immunoassay. Anti-Ro 60 IgG was eluted from early apoptotic cells or recombinant Ro 60 immobilized on nitrocellulose, and binding to membrane-bound and intracellular forms of Ro 60 was quantitated by flow cytometry. RESULTS An immunodominant apotope, which was recognized by IgG from a subset of SLE patients with anti-Ro, but not anti-La, autoantibodies, was mapped to a region forming a helix-loop-helix at the apical tip of the Ro 60 molecule. Immobilization of this region to the solid phase exposed an epitope that was recognized by IgG from primary SS and SLE patients whose sera had both anti-Ro and anti-La autoantibodies. Autoantibodies eluted from either the surface of apoptotic cells or the Ro 60 epitope on the solid phase were non-cross-reactive and specifically recognized membrane-bound or cytoplasmic forms of Ro 60. CONCLUSION This is the first example of a dichotomy of human autoantibody responses against mutually exclusive determinants linked to a single domain of a systemic autoantigen and supports a model in which tolerance is broken by different immunogenic forms of Ro 60.
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Affiliation(s)
- Joanne H Reed
- Flinders Medical Centre, Bedford Park, South Australia, Australia
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Transcriptional control of the calreticulin gene in health and disease. Int J Biochem Cell Biol 2009; 41:531-8. [DOI: 10.1016/j.biocel.2008.06.020] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Revised: 06/10/2008] [Accepted: 06/13/2008] [Indexed: 11/22/2022]
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Abstract
Apoptosis has been proposed to influence the initiation and diversification of autoimmunity to the Ro (SSA)/La (SSB) ribonucleoprotein (RNP) particle and serve as a target for autoantibody-mediated tissue injury. We have developed a new approach to B cell epitope mapping which identifies "apotopes," defined as epitopes expressed on the surface of apoptotic cells. Preliminary studies support a role for apotopes as diagnostic markers in systemic lupus erythematosus (SLE) and primary Sjögren's syndrome. For example, apotopes within the NH(2)-terminal and central regions of La react with the majority of sera from mothers of infants with congenital heart block. Furthermore, a Ro60 apotope is specific for a subset of SLE with isolated anti-Ro60 responses. The mapping of B cell apotopes may prove superior to standard epitope mapping by suggesting novel pathways of autoantibody production and identifying pathogenic species of autoantibodies.
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Affiliation(s)
- Joanne H Reed
- Department of Immunology, Flinders Medical Centre, Bedford Park, South Australia 5042, Australia.
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Lin JH, Dutz JP, Sontheimer RD, Werth VP. Pathophysiology of Cutaneous Lupus Erythematosus. Clin Rev Allergy Immunol 2007; 33:85-106. [DOI: 10.1007/s12016-007-0031-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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11
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Abstract
Heat-shock or stress proteins (HSPs) are intracellular molecules that are expressed under cellular stress and have housekeeping and cytoprotective functions. Many of them act also as molecular chaperones, assisting the correct folding, stabilization, and translocation of proteins. In pathological situations, such as necrotic cell death, they can be released into the extracellular environment complexed with intact or fragmented cellular proteins. Evidence is now accumulating to indicate that, under certain circumstances, these complexes can contribute to induction of autoimmunity by receptor-mediated activation of the innate immune response (signaling the "danger") and by participation in the presentation of autoantigens for the adaptive immune response (acting as natural adjuvants). In addition, the conservation of HSPs through prokaryotes and eukaryotes, together with the increased production of host and microbial HSPs at the site of infection, has led to the proposition that these proteins may provide a link between infection and autoimmunity. This review outlines the mechanisms for the potential involvement of chaperones in the induction of autoimmune disease.
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Affiliation(s)
- John G Routsias
- Department of Pathophysiology, School of Medicine, University of Athens, 11527 Athens, Greece
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12
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Subacute Cutaneous Lupus Erythematosus: A Quarter Century's Perspective. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/s1571-5078(05)05007-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Neufing PJ, Clancy RM, Jackson MW, Tran HB, Buyon JP, Gordon TP. Exposure and binding of selected immunodominant La/SSB epitopes on human apoptotic cells. ARTHRITIS AND RHEUMATISM 2005; 52:3934-42. [PMID: 16320341 DOI: 10.1002/art.21486] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Opsonization of apoptotic cells by autoantibodies bound to surface membrane-translocated La/SSB antigens may initiate tissue damage in the setting of congenital heart block. By injecting pregnant mice with human anti-La antibodies, we previously demonstrated the formation of IgG-apoptotic cell complexes in the developing mouse fetus; however, the binding of anti-La antibodies to human-specific epitopes could not be addressed. Accordingly, the objective of the current study was to delineate the epitope specificity of human La antibodies that are exposed on the surface of apoptotic cells. METHODS We used fluorescence microscopy and flow cytometry to assess the binding of human anti-La antibodies affinity purified against immunodominant epitopes of La to human cells undergoing spontaneous apoptosis, in a murine xenograft model in vivo and in cultured human fetal cardiocytes rendered apoptotic in vitro, respectively. RESULTS Anti-La antibodies bound to immunodominant epitopes of La within the NH(2)-terminus and the RNA recognition motif (RRM) region of apoptotic human cells, in both xenografts and fetal cardiocytes. In contrast, human antibodies affinity purified against the COOH-terminal La epitope did not bind apoptotic cells in either model. This defines the topology of redistributed La during apoptosis, with surface exposure of the NH(2)-terminus and RRM regions. The potential importance of anti-La NH(2)-terminal and anti-La RRM specificity was confirmed by detection of this reactivity in mothers of children with congenital heart block. CONCLUSION These findings provide insight into both the molecular modification of the La autoantigen during apoptosis and the specificity of antibodies capable of binding to surface-exposed La. Subsequent formation of surface immune complexes may lead to tissue injury in patients with autoimmune diseases such as congenital heart block.
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Affiliation(s)
- Petra J Neufing
- Department of Immunology, Allergy and Arthritis, Flinders University, Adelaide, South Australia, Australia.
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Deshmukh US, Bagavant H, Lewis J, Gaskin F, Fu SM. Epitope spreading within lupus-associated ribonucleoprotein antigens. Clin Immunol 2005; 117:112-20. [PMID: 16095971 DOI: 10.1016/j.clim.2005.07.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Accepted: 07/07/2005] [Indexed: 12/11/2022]
Abstract
Autoantibodies reactive with several cellular antigens are present in the sera of patients with systemic lupus erythematosus. Polypeptides within the Ro-RNP complex and the snRNP complex are often targeted by these autoantibodies. One of the mechanisms responsible for their evolution is that of epitope spreading. Experimental animal model systems provide evidence for this. This review discusses the animal model systems of epitope spreading within these ribonucleoprotein antigens, the mechanisms of epitope spreading, and its relevance for disease pathogenesis.
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Affiliation(s)
- Umesh S Deshmukh
- Division of Rheumatology and Immunology, Specialized Center of Research on Systemic Lupus Erythematosus, Department of Internal Medicine, HSC Box 800412, University of Virginia, Charlottesville, VA 22908, USA.
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Routsias JG, Kosmopoulou A, Makri A, Panou-Pomonis E, Sakarellos C, Sakarellos-Daitsiotis M, Moutsopoulos HM, Tzioufas AG. Zinc Ion Dependent B-Cell Epitope, Associated with Primary Sjogren's Syndrome, Resides within the Putative Zinc Finger Domain of Ro60kD Autoantigen: Physical and Immunologic Properties. J Med Chem 2004; 47:4327-34. [PMID: 15294004 DOI: 10.1021/jm049844+] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Ro/La ribonucleoprotein (RNP) complex is composed of the proteins Ro60kD, Ro52kD, and La48kD that are in association with one small cytoplasmic RNA (YRNA). Specific protein-RNA and protein-protein interactions are thought to occur through the RNP and zinc-finger secondary structure elements of the Ro60kD protein. The aim of our study was to investigate the antigenic properties of the zinc finger domain of the Ro60KD autoantigen and its contribution to the formation of Ro/La RNP complex. It was found that the peptide VSLVCEKLCNEKLLKKARIHPFHILIA (Zif-1), which corresponds to the natural sequence of the zinc finger domain (301-327), and the peptide C(Acm)NEKLLKKARIC(Acm), analogous to the intermediate loop 310-319 (Zif-3) of the same domain of Ro60KD, are recognized by the majority of anti-Ro/SSA and anti-La/SSB positive sera (82.6% and 77.1%, respectively) in the absence of zinc ions. The same sera failed to react with Zif-1 peptide in the presence of Zn2+. In contrast, the addition of zinc ions was necessary for the binding of Zif-1 to recombinant Ro52KD as shown by direct binding experiments of the recombinant protein with synthetic peptides. Our data suggest the zinc finger domain of Ro60kD contains a B-cell epitope with high specificity for primary Sjogren's syndrome. Furthermore, depending on the presence of zinc ions, the zinc finger domain of the Ro60KD protein can exist in two different conformational states favoring either an interaction with the Ro52KD protein or binding with autoantibodies.
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Affiliation(s)
- John G Routsias
- Department of Pathophysiology, School of Medicine, University of Athens, 11527 Athens, Greece
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McClain MT, Lutz CS, Kaufman KM, Faig OZ, Gross TF, James JA. Structural availability influences the capacity of autoantigenic epitopes to induce a widespread lupus-like autoimmune response. Proc Natl Acad Sci U S A 2004; 101:3551-6. [PMID: 14988508 PMCID: PMC373500 DOI: 10.1073/pnas.0306267101] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2003] [Indexed: 11/18/2022] Open
Abstract
A subset of lupus patients with severe nephritis and anti-nRNP reactivity produces autoantibodies primarily against two major epitopes of the nRNP A (also known as U1A) protein. These sequences span amino acids 44-56 (A3) and amino acids 103-115 (A6). These two epitopes represent structurally different regions of the protein, as both epitopes are located on the surface, but the A6 epitope is functionally masked in vivo by binding between nRNP A and the U1 RNA. Rabbits were immunized with either the A3 or A6 peptides constructed on a branching polylysine backbone. Rabbits immunized with each of these peptides first developed antibodies directed against the peptide of immunization. With boosting, the immune response of rabbits immunized with the A3 peptide spread to other common antigenic regions of nRNP A. These regions of nRNP A bound by A3 immunized rabbits are very similar to common epitopes in human systemic lupus erythematosus. These A3 immunized rabbits also develop antibodies to common antigenic regions of nRNP 70K, nRNP C, Sm B/B', and Sm D1 proteins, as well as clinical symptoms of systemic lupus erythematosus such as leukopenia and renal insufficiency. On the other hand, rabbits immunized with the A6 peptide only develop antibodies to the peptide of immunization. Anti-A3, but not anti-A6, antibodies are capable of immunoprecipitating native small nuclear ribonucleoprotein complexes. Immunization with the A3 peptide of nRNP A (a surface epitope), but not the A6 peptide (masked), induces an extensive, varied immune response against multiple small nuclear ribonucleoprotein autoantigens similar to that seen in human systemic lupus erythematosus.
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Affiliation(s)
- Micah T McClain
- Oklahoma Medical Research Foundation, University of Oklahoma Health Sciences Center, and Veterans Affairs Medical Center, Oklahoma City, OK 73104, USA
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Purcell AW, Todd A, Kinoshita G, Lynch TA, Keech CL, Gething MJ, Gordon TP. Association of stress proteins with autoantigens: a possible mechanism for triggering autoimmunity? Clin Exp Immunol 2003; 132:193-200. [PMID: 12699405 PMCID: PMC1808692 DOI: 10.1046/j.1365-2249.2003.02153.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Patterns of autoantibody production are diagnostic of many autoimmune disorders; the recent observation of additional autospecificities towards stress-induced proteins may also provide insight into the mechanisms by which such responses arise. Grp78 (also known as BiP) is a target of autoaggressive B and T cell responses in our murine model of anti-Ro (SS-A) autoimmunity and also in rheumatoid arthritis. In this report we demonstrate reciprocal intermolecular spreading occurs between Ro52 and Grp78 in immunized mice, reflecting physiological association of these molecules in vivo. Moreover, we provide direct biochemical evidence that Grp78 associates with the clinically relevant autoantigen, Ro52 (SS-A). Due to the discrete compartmentalization of Ro52 (nucleocytoplasmic) and Grp78 (endoplasmic reticulum; ER) we propose that association of these molecules occurs either in apoptotic cells, where they have been demonstrated indirectly to co-localize in discrete apoptotic bodies, or in B cells themselves where both Ro52 and Grp78 are known to bind to immunoglobulin heavy chains. Tagging of molecules by association with Grp78 may facilitate receptor mediated phagocytotsis of the complex; we show evidence that exogenous Grp78 can associate with cell surface receptors on a subpopulation of murine splenocytes. Given the likelihood that Grp78 will associate with viral glycoproteins in the ER it is possible that it may become a bystander target of the spreading antiviral immune response. Thus, we propose a model whereby immunity elicited towards Grp78 leads to the selection of responses towards the Ro polypeptides and the subsequent cascade of responses observed in human disease.
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Affiliation(s)
- A W Purcell
- Department of Microbiology and Immunology, University of Melbourne, Victoria, Australia.
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Scofield RH, Pierce PG, James JA, Kaufman KM, Kurien BT. Immunization with peptides from 60 kDa Ro in diverse mouse strains. Scand J Immunol 2002; 56:477-83. [PMID: 12410797 DOI: 10.1046/j.1365-3083.2002.01159.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Antibodies binding the Ro (or SSA) and La (or SBB) proteins are commonly found in a high proportion of sera from patients with systemic lupus erythematosus or Sjögren's syndrome. The mechanism by which these autoantibodies arise is not known. Others and we have shown that immunization of nonautoimmune-prone mice with short peptides from the Ro ribonucleoprotein particle can induce autoimmunity to 60 kDa Ro and 52 kDa Ro as well as to the 48 kDa La protein after epitope spreading. We have explored the differences in the epitope spreading after 60 kDa Ro peptide immunization in several strains of mice. There is intra- and intermolecular diversification of the immune response after immunization of DBA/2J animals with a monomer peptide representing the residues 480-494 of the 60 kDa Ro protein, but this peptide does not induce epitope spreading when used as the immunogen in either C57Bl/6J or PL/J mice. Similar to previously studied BALB/c mice, DBA/2J mice have antibodies binding many epitopes of 60 kDa Ro, and some sera bind 52 kDa Ro as well as La. These mice have antinuclear antibody in their sera. These data demonstrate that Ro peptide immunization results in different outcomes depending upon the strain of mouse used. Furthermore, these data suggest that genetic variation is important with regard to responding towards short peptide immunization by epitope spreading.
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Affiliation(s)
- R H Scofield
- Arthritis and Immunology Program, Oklahoma Medical Research Foundation, Department of Medicine, University of Oklahoma Health Sciences Center and the Department of Veterans Affairs Medical Center, Oklahoma City, OK 73105, USA.
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Gordon TP, Kinoshita G, Cavill D, Keech C, Farris A, Kaufman K, McCluskey J, Purcell A. Restricted specificity of intermolecular spreading to endogenous La (SS-B) and 60 kDa Ro (SS-A) in experimental autoimmunity. Scand J Immunol 2002; 56:168-73. [PMID: 12121436 DOI: 10.1046/j.1365-3083.2002.01115.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Intermolecular spreading of humoral autoimmunity to different components of the Ro (SS-A) and La (SS-B) ribonucleoprotein (RNP) complex has been reported following immunization with a single component of the complex. Although the immune response to the immunizing antigen is polyclonal and diversified, little is known about the specificity of the recruited autoimmune responses to the endogenous Ro and La antigens which drive B-cell spreading. To determine the specificity of intermolecular spreading to La, we examined sera from 52 kDa Ro (Ro52)- and 60 kDa Ro (Ro60)-immunized C3H/HeJ mice for reactivity with recombinant fragments spanning endogenous mouse (m)La by enzyme-linked immunosorbent assay (ELISA) and immunoblotting. Sera from mice primed and boosted with recombinant Ro52 and Ro60 showed reactivity restricted to the COOH-terminal fragment of mLa (aa361-415). The recruited anti-La response was species-specific, cross-reacting weakly with the corresponding region on the human La molecule, and was abrogated by the preabsorption of the Ro-immune sera with mLa 361-415. Analogous experiments using recombinant mRo60 fragments spanning the mRo60 molecule revealed a similar pattern of oligoclonality in the specificity of anti-Ro60 autoimmunity following active immunization with La and Ro52. These results suggest that intermolecular-intrastructural T-B help is limiting in this model, and reveal unsuspected immunodominance of selected Ro-La epitopes in the spreading of the autoantibody response to these structures. The focusing of the recruited autoantibody response to these COOH-terminal regions of the Ro and La polypeptides may also reflect the surface accessibility of these regions in La-Ro RNP.
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Affiliation(s)
- T P Gordon
- Department of Immunology, Allergy and Arthritis, Flinders Medical Centre and University, Adelaide, Australia.
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Rhodes DA, Ihrke G, Reinicke AT, Malcherek G, Towey M, Isenberg DA, Trowsdale J. The 52 000 MW Ro/SS-A autoantigen in Sjögren's syndrome/systemic lupus erythematosus (Ro52) is an interferon-gamma inducible tripartite motif protein associated with membrane proximal structures. Immunology 2002; 106:246-56. [PMID: 12047754 PMCID: PMC1782712 DOI: 10.1046/j.1365-2567.2002.01417.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 52 000 MW Ro/SS-A (Ro52) protein is a major target of autoantibodies in autoimmune conditions such as systemic lupus erythematosus and Sjögren's syndrome. Recent genomic and bioinformatic studies have shown that Ro52 belongs to a large family of related RING/Bbox/coiled-coil (RBCC) tripartite motif proteins sharing overall domain structure and 40-50% identity at the amino acid level. Ro52 also has a B30.2 domain at the C-terminus. Using the human genome draft sequence, the genomic organization of the Ro52 gene on human chromosome 11p15.5 has been deduced and related to the protein domain structure. We show that the steady-state levels of Ro52 mRNA are normally very low but are induced by cell activation with interferon-gamma. In transient transfection of HeLa cells, epitope-tagged Ro52 protein was localized to unidentified membrane proximal rod-like structures. Using in vitro coupled transcription/translation followed by immunoprecipitation, the autoimmune response to Ro52 protein was investigated and two distinct interactions were resolved. The Ro52 C-terminal B30.2 domain interacts with human immunoglobulin independently of antibody specificities. Sera derived from patients with Sjögren's syndrome and systemic lupus erythematosus, in addition, contained specific autoantibodies directed towards the rest of the Ro52 molecule. The majority of these autoimmune sera also immunoprecipitated the Ro52-related molecule RNF15. A possible role for Ro52 protein in alterations of plasma membranes during cellular activation or apoptosis is discussed.
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Affiliation(s)
- Davd A Rhodes
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge UK.
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Wenzel J, Gerdsen R, Uerlich M, Bauer R, Bieber T, Boehm I. Antibodies targeting extractable nuclear antigens: historical development and current knowledge. Br J Dermatol 2001; 145:859-67. [PMID: 11899137 DOI: 10.1046/j.1365-2133.2001.04577.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- J Wenzel
- Department of Dermatology, University of Bonn, Germany.
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Abstract
Neonatal lupus is a disease characterized by one or more of the following findings: congenital heart block, cardiomyopathy, cutaneous lupus lesions, hepatobiliary disease, and thrombocytopenia. Accumulating evidence indicates that the disease is probably caused by maternal autoantibodies, particularly autoantibodies of the Ro family. While often initially asymptomatic, mothers tend to develop symptoms of connective tissue disease. This review discusses the recent advances in the understanding of neonatal lupus, its clinical features, therapy, and pathogenesis.
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Affiliation(s)
- L A Lee
- Department of Dermatology, University of Colorado School of Medicine, 4200 East Ninth Avenue, Denver, CO 80262, USA.
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Johnson RJ, Xiao G, Shanmugaratnam J, Fine RE. Calreticulin functions as a molecular chaperone for the β-amyloid precursor protein 1 1Abbreviations used: Aβ, β-amyloid peptide; AD, Alzheimer’s disease; APP, β-amyloid precursor protein; CHAPS, 3-[(3-Cholamidopropyl)-dimethylammonio]-1-propanesulfonate; Crt, calreticulin; DMEM, Dulbecco’s Modified Eagle Medium; DMJ, deoxymannojirimycin; DTSSP, 3,3′-Dithio bis (sulfosuccinimidylpropionate); ECL, Enhanced Chemiluminescence; ER, endoplasmic reticulum; FBS, fetal bovine serum; HRP, horseradish peroxidase; kDa, kiloDaltons; MES, 2-(N-Morpholino) ethane sulfonic acid; NRS, normal rabbit serum; PBS, PBS; PMSF, phenymethylsulfonyl fluoride; PVDF, polyvinylidene fluoride. Neurobiol Aging 2001; 22:387-95. [PMID: 11378243 DOI: 10.1016/s0197-4580(00)00247-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Processing of the beta-amyloid precursor protein (APP) in the endoplasmic reticulum and the Golgi apparatus may be critical in generating the beta-amyloid molecules linked to the pathogenesis of Alzheimer's disease. Since chaperone molecules such as calreticulin (Crt) have been shown to be important in the maturation of many glycoproteins, we investigated the interaction between Crt and APP. We show that APP binds transiently to Crt in a manner that is pH, divalent cation, and N-linked glycosylation-dependent. Both immature APP (containing only N-linked sugars) and mature APP (containing both N-linked and O-linked sugars) bind to Crt. Both proteins are part of a complex that appears to be large enough to accommodate other proteins as well. However, while most of the immature form is associated with the complexes, very little of the mature form is. The interaction between APP and Crt is likely to be of physiological significance with respect to APP maturation since Crt is involved in quality control of nascent glycoproteins in the secretory pathway.
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Affiliation(s)
- R J Johnson
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA.
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26
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Deshmukh US, Lewis JE, Gaskin F, Dhakephalkar PK, Kannapell CC, Waters ST, Fu SM. Ro60 peptides induce antibodies to similar epitopes shared among lupus-related autoantigens. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:6655-61. [PMID: 10843726 DOI: 10.4049/jimmunol.164.12.6655] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The coexistence of autoantibodies to ribonucleoproteins (RNP) in sera of patients with systemic lupus erythematosus has been attributed to intermolecular determinant spreading among physically associated proteins. Recently, we showed that murine Ab responses to rRo60 or Ro60 peptides were diversified unexpectedly to small nuclear RNP. In this investigation, the mechanisms for this autoantibody diversification were examined. Intramolecular determinant spreading was demonstrated in mice immunized with human or mouse Ro60316-335. Immune sera depleted of anti-peptide Ab immunoprecipitated Ro60-associated mY1 and mY3 RNA and remained reactive to a determinant on Ro60128-285. Absorption with the immunogen depleted the immune sera completely of anti-Golgi complex Ab (inducible only with human Ro60316-335) and anti-La Ab, and reduced substantially Ab to SmD and 70-kDa U1RNP. Mouse rRo60 completely inhibited the immune sera reactivity to La, SmD, and 70-kDa U1RNP. However, La, SmD, and 70-kDa U1RNP preferentially inhibited the antiserum reactivities to these Ags, respectively. Affinity-purified anti-La Ab were reactive with Ro60, La, SmD, and 70-kDa U1RNP. These results provide evidence that a population of the induced autoantibodies recognized determinants shared by these autoantigens. Lack of sequence homology between Ro60316-335 and La, SmD, or 70-kDa U1RNP suggests that these determinants are conformational. Interestingly, similar cross-reactive autoantibodies were found in NZB/NZW F1 sera. Thus, a single molecular mimic may generate Ab to multiple RNP Ags. Furthermore, cross-reactive determinants shared between antigenic systems that are not associated physically (Ro/La RNP and small nuclear RNP) may be important in the generation of autoantibody diversity in systemic lupus erythematosus.
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MESH Headings
- Absorption
- Amino Acid Sequence
- Animals
- Antigens, Heterophile/administration & dosage
- Antigens, Heterophile/immunology
- Antigens, Heterophile/metabolism
- Autoantibodies/biosynthesis
- Autoantibodies/metabolism
- Autoantigens/administration & dosage
- Autoantigens/immunology
- Autoantigens/metabolism
- Cross Reactions
- Crosses, Genetic
- Epitopes, B-Lymphocyte/immunology
- Epitopes, B-Lymphocyte/metabolism
- Female
- Humans
- Lupus Erythematosus, Systemic/immunology
- Mice
- Mice, Inbred A
- Mice, Inbred BALB C
- Mice, Inbred NZB
- Molecular Sequence Data
- Peptide Fragments/administration & dosage
- Peptide Fragments/immunology
- Peptide Fragments/metabolism
- RNA, Small Cytoplasmic
- Ribonucleoproteins/administration & dosage
- Ribonucleoproteins/immunology
- Ribonucleoproteins/metabolism
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Affiliation(s)
- U S Deshmukh
- Department of Internal Medicine, University of Virginia Specialized Center of Research on Systemic Lupus Erythematosus, Charlottesville 22908, USA
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Eggleton P, Ward FJ, Johnson S, Khamashta MA, Hughes GR, Hajela VA, Michalak M, Corbett EF, Staines NA, Reid KB. Fine specificity of autoantibodies to calreticulin: epitope mapping and characterization. Clin Exp Immunol 2000; 120:384-91. [PMID: 10792392 PMCID: PMC1905652 DOI: 10.1046/j.1365-2249.2000.01214.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Extracellular calreticulin (CRT) as well as anti-CRT antibodies have been reported in patients with various autoimmune disorders and CRT has been implicated in 'epitope spreading' to other autoantigens such as the Ro/SS-A complex. In addition, antibodies against parasite forms of the endoplasmic reticulum chaperone, CRT, have been found in patients suffering from onchocerciasis and schistosomiasis. In this study, we screened sera for anti-CRT antibodies from patients with active and inactive systemic lupus ertythematosus (SLE) and primary or secondary Sjögren's syndrome. Approximately 40% of all SLE patients were positive for anti-CRT antibodies. The antigenic regions of CRT were determined using full length CRT and fragments of CRT prepared in yeast and Escherichia coli, respectively. Synthetic 15mer peptides corresponding to the major autoantigenic region of CRT (amino acids 1-289), each one overlapping by 12 amino acids, were used to map the B cell epitopes on the CRT protein recognized by autoimmune sera. Major antigenic epitopes were found to be associated with the N-terminal half of the protein in 69% of the SLE sera from active disease patients, while the C-domain was not antigenic. Major epitopes were found to be reactive with antibodies in sera from SLE patients with both active and inactive disease, spanning different regions of the N and P-domains. Sera from both healthy and disease controls and primary Sjögren's syndrome patients were non-reactive to these sequences. Limited proteolysis of CRT with two major leucocyte serine proteases, elastase and cathepsin G, demonstrated that an N-terminal region of CRT is resistant to digestion. Interestingly, some of the epitopes with the highest reactivity belong to the fragments of the protein which bind to C1q and inhibit complement activation. Whether C1q association with CRT is a pathological or protective interaction between these two proteins is currently under investigation.
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Affiliation(s)
- P Eggleton
- MRC Immunochemistry Unit, Department of Biochemistry, University of Oxford, Oxford, UK
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Abstract
BACKGROUND Immunization of laboratory animals is a new model system for systemic lupus erythematosus (SLE) and the autoimmunity of SLE. OBJECTIVE Review the published reports describing immunization as a model of SLE and describe the state of this research as well as future objectives as related to human illness. METHODS Medline search for relevant articles as well as review of cited bibliographies. RESULTS Either rabbits or mice can be immunized with proteins or oligopeptides that are lupus autoantigens with a resulting immune response not just to the immunogen but instead to a host of other self components that are also SLE-associated autoantigens. Several studies have noted clinical illness in these animals that resembles human SLE. In addition, injection of pristane (a component of mineral oil) also results in SLE-like autoimmunity, even though lupus autoantigens are not present. Pristane injected animals may also develop an SLE-like illness. There are reports of human SLE having its onset after immunization, but there have been no prospective studies. CONCLUSIONS Studies are needed to determine whether human SLE tends to begin soon after immunization. Meanwhile, continued study of animal models developed after immunization is needed in order to determine the relevance of this model to human disease. RELEVANCE SLE and/or SLE-like autoimmunity can be triggered after immunization of animals. This may be a model for an environmental trigger of human SLE.
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Affiliation(s)
- R H Scofield
- Oklahoma Medical Research Foundation and the University of Oklahoma Health Sciences Center, Oklahoma City 73104, USA
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Generation of a Monoclonal Antibody Against Human Calreticulin by Immunization with a Recombinant Calreticulin Fusion Protein: Application in Paraffin-Embedded Sections. Appl Immunohistochem Mol Morphol 1999. [DOI: 10.1097/00129039-199906000-00008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Kinoshita G, Purcell AW, Keech CL, Farris AD, McCluskey J, Gordon TP. Molecular chaperones are targets of autoimmunity in Ro(SS-A) immune mice. Clin Exp Immunol 1999; 115:268-74. [PMID: 9933452 PMCID: PMC1905168 DOI: 10.1046/j.1365-2249.1999.00794.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/1998] [Indexed: 11/20/2022] Open
Abstract
We have used a murine model of experimental anti-Ro(SS-A) autoimmunity to dissect additional intermolecular interactions between the 52-kD Ro (Ro52) and 60-kD Ro (Ro60) autoantigens and molecular chaperones. Immune responses to members of the heat shock protein hsp70 and hsp90 families were measured by immunoblotting and ELISA in sera from mice immunized and boosted with purified recombinant Ro52, Ro60 and La (SS-B). All Ro52 and Ro60 immune sera immunoblotted the inducible glucose-regulated protein grp78 and hsp70 species but not constitutive hsc70 or hsp90. The kinetics of antibody production and reciprocal affinity purification experiments indicated that the grp78 and hsp70 responses were cross-reactive but distinct from immune responses to the primary Ro52 and Ro60 immunogens and the endoplasmic reticulum (ER)-resident chaperone calreticulin. No responses to molecular chaperones were detected in the La-immunized mice. Control immunizations indicated that the recruited grp78 and hsp70 responses were specific for the Ro proteins and not due to immunization with denatured protein. The rapid spreading of immunity to the inducible grp78 and hsp70 in Ro52- and Ro60-immunized mice suggests that these components may co-localize and physically associate under certain physiological conditions which may promote autoimmunization. The potential importance of the ER-resident chaperones grp78 and calreticulin is further supported by their co-localization with Ro in small apoptotic membrane blebs and the finding of a novel putative grp78 binding motif in the carboxyl-terminal region of Ro52.
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Affiliation(s)
- G Kinoshita
- Department of Immunology, Allergy & Arthritis, Flinders Medical Centre and Flinders University, Adelaide, South Australia
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31
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McCluskey J, Farris AD, Keech CL, Purcell AW, Rischmueller M, Kinoshita G, Reynolds P, Gordon TP. Determinant spreading: lessons from animal models and human disease. Immunol Rev 1998; 164:209-29. [PMID: 9795778 DOI: 10.1111/j.1600-065x.1998.tb01222.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Spreading of the immune response is a common theme in organ-specific and systemic autoimmune diseases. We evaluated whether some of the mixed antinuclear antibody patterns characteristic of systemic autoimmunity might be the result of determinant spreading from a single initiating event. Immunisation of healthy mice with individual protein components of the La/Ro ribonucleoprotein (RNP) targeted in systemic lupus erythematosus and primary Sjögren's syndrome induced autoantibodies recognising Ro60 (SS-A), Ro52 (SS-A) and La (SS-B) and in some cases the molecular chaperones calreticulin and Grp78. The endogenous antigen(s) driving determinant spreading might be derived from physiological apoptosis which could explain the involvement of some chaperone proteins in the autoimmune response. Diversified anti-La/Ro antibody responses were initiated by challenge with a single subdominant T epitope of La even though some self epitopes of La were efficiently tolerised. The pattern of autoantibody responses in primary Sjögren's syndrome was strongly influenced by HLA class II phenotype which we speculate controls activation of T cells recognising defined peptides from the La/Ro RNP. In this way, HLA class II alleles may be critical in influencing initiation and spreading of systemic autoimmune reactions. Molecular mimicry of such determinants by exogenous agents might readily initiate spreading of an autoimmune response in genetically susceptible hosts.
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Affiliation(s)
- J McCluskey
- Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria, Australia.
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