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Moura MC, Thompson GE, Nelson DR, Fussner LA, Hummel AM, Jenne DE, Emerling D, Fervenza FC, Kallenberg CGM, Langford CA, McCune WJ, Merkel PA, Monach PA, Seo P, Spiera RF, St. Clair EW, Ytterberg SR, Stone JH, Robinson WH, Specks U. Activation of a Latent Epitope Causing Differential Binding of Antineutrophil Cytoplasmic Antibodies to Proteinase 3. Arthritis Rheumatol 2023; 75:748-759. [PMID: 36515151 PMCID: PMC10191989 DOI: 10.1002/art.42418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 11/17/2022] [Accepted: 12/08/2022] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Proteinase 3 (PR3) is the major antigen for antineutrophil cytoplasmic antibodies (ANCAs) in the systemic autoimmune vasculitis, granulomatosis with polyangiitis (GPA). PR3-targeting ANCAs (PR3-ANCAs) recognize different epitopes on PR3. This study was undertaken to study the effect of mutations on PR3 antigenicity. METHODS The recombinant PR3 variants, iPR3 (clinically used to detect PR3-ANCAs) and iHm5 (containing 3 point mutations in epitopes 1 and 5 generated for epitope mapping studies) immunoassays and serum samples from patients enrolled in ANCA-associated vasculitis (AAV) trials were used to screen for differential PR3-ANCA binding. A patient-derived monoclonal ANCA 518 (moANCA518) that selectively binds to iHm5 within the mutation-free epitope 3 and is distant from the point mutations of iHm5 was used as a gauge for remote epitope activation. Selective binding was determined using inhibition experiments. RESULTS Rather than reduced binding of PR3-ANCAs to iHm5, we found substantially increased binding of the majority of PR3-ANCAs to iHm5 compared to iPR3. This differential binding of PR3-ANCA to iHm5 is similar to the selective moANCA518 binding to iHm5. Binding of iPR3 to monoclonal antibody MCPR3-2 also induced recognition by moANCA518. CONCLUSION The preferential binding of PR3-ANCAs from patients, such as the selective binding of moANCA518 to iHm5, is conferred by increased antigenicity of epitope 3 on iHm5. This can also be induced on iPR3 when captured by monoclonal antibody MCPR2. This previously unrecognized characteristic of PR3-ANCA interactions with its target antigen has implications for studying antibody-mediated autoimmune diseases, understanding variable performance characteristics of immunoassays, and design of potential novel treatment approaches.
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Affiliation(s)
- Marta Casal Moura
- Mayo Clinic and Foundation, Rochester, MN, USA
- Faculdade de Medicina da Universidade do Porto, Porto, Portugal
| | | | | | - Lynn A. Fussner
- Mayo Clinic and Foundation, Rochester, MN, USA
- Ohio State University, Columbus, OH, USA
| | | | - Dieter E. Jenne
- Max-Planck-Institute for Biological Intelligence, 82152 Martinsried, Germany
| | | | | | | | | | | | | | - Paul A. Monach
- VA Boston Healthcare System, Rheumatology, Boston, MA, USA
| | - Philip Seo
- Johns Hopkins University, Baltimore, MD, USA
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2
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Berti A, Hillion S, Konig MF, Moura MC, Hummel AM, Carmona E, Peikert T, Fervenza FC, Kallenberg CGM, Langford CA, Merkel PA, Monach PA, Seo P, Spiera RF, Brunetta P, Clair EW, Harris KM, Stone JH, Grandi G, Pers JO, Specks U, Cornec D. Autoreactive Plasmablasts After B Cell Depletion With Rituximab and Relapses in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis. Arthritis Rheumatol 2023; 75:736-747. [PMID: 36281741 PMCID: PMC10280646 DOI: 10.1002/art.42388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/04/2022] [Accepted: 10/11/2022] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Autoreactive B cells are responsible for antineutrophil cytoplasmic antibody (ANCA) production in ANCA-associated vasculitis (AAV). Rituximab (RTX) depletes circulating B cells, including autoreactive B cells. We aimed to evaluate changes and associations with relapse of the circulating autoreactive B cell pool following therapeutic B cell depletion in AAV. METHODS Sequential flow cytometry was performed on 148 samples of peripheral blood mononuclear cells from 23 patients with proteinase 3 (PR3)-ANCA-positive AAV who were treated with RTX for remission induction and monitored after stopping therapy during long-term follow-up in a prospective clinical trial. PR3 was used as a ligand to target autoreactive PR3-specific (PR3+) B cells. B cell recurrence was considered as the first blood sample with ≥10 B cells/μl after RTX treatment. RESULTS At B cell recurrence, PR3+ B cell frequency among B cells was higher than baseline (P < 0.01). Within both PR3+ and total B cells, frequencies of transitional and naive subsets were higher at B cell recurrence than at baseline, while memory subsets were lower (P < 0.001 for all comparisons). At B cell recurrence, frequencies of B cells and subsets did not differ between patients who experienced relapse and patients who remained in remission. In contrast, the plasmablast frequency within the PR3+ B cell pool was higher in patients who experienced relapse and associated with a shorter time to relapse. Frequencies of PR3+ plasmablasts higher than baseline were more likely to be found in patients who experienced relapse within the following 12 months compared to those in sustained remission (P < 0.05). CONCLUSION The composition of the autoreactive B cell pool varies significantly following RTX treatment in AAV, and early plasmablast enrichment within the autoreactive pool is associated with future relapses.
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Affiliation(s)
- Alvise Berti
- Division of Pulmonary & Critical Care Medicine, Thoracic Disease Research Unit, Mayo Clinic, Rochester, Minnesota, and Center for Medical Sciences (CISMed), Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Italy, and Rheumatology Unit, Santa Chiara Hospital, APSS Trento, Italy
| | - Sophie Hillion
- Jacques-Olivier Pers, DDS, PhD, Divi Cornec, MD, PhD: Université de Bretagne Occidendale, Brest, Bretagne, France
| | - Maximilian F. Konig
- Division of Rheumatology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Marta Casal Moura
- Division of Pulmonary & Critical Care Medicine, Thoracic Disease Research Unit, Mayo Clinic, Rochester, Minnesota
| | - Amber M. Hummel
- Division of Pulmonary & Critical Care Medicine, Thoracic Disease Research Unit, Mayo Clinic, Rochester, Minnesota
| | - Eva Carmona
- Division of Pulmonary & Critical Care Medicine, Thoracic Disease Research Unit, Mayo Clinic, Rochester, Minnesota
| | - Tobias Peikert
- Division of Pulmonary & Critical Care Medicine, Thoracic Disease Research Unit, Mayo Clinic, Rochester, Minnesota
| | | | - Cees G. M. Kallenberg
- Department of Rheumatology and Clinical Immunology, University of Groningen, Groningen, The Netherlands
| | | | - Peter A. Merkel
- Division of Rheumatology, Department of Medicine, and Department of Biostatistics, Epidemiology, and Informatics, Division of Clinical Epidemiology, University of Pennsylvania, Philadelphia
| | | | - Philip Seo
- Division of Rheumatology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Robert F. Spiera
- Weill Cornell Medical College, Hospital for Special Surgery, New York
| | | | | | | | - John H. Stone
- Massachusetts General Hospital Rheumatology Unit, Boston
| | - Guido Grandi
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Italy
| | - Jacques-Olivier Pers
- Jacques-Olivier Pers, DDS, PhD, Divi Cornec, MD, PhD: Université de Bretagne Occidendale, Brest, Bretagne, France
| | - Ulrich Specks
- Division of Pulmonary & Critical Care Medicine, Thoracic Disease Research Unit, Mayo Clinic, Rochester, Minnesota
| | - Divi Cornec
- Jacques-Olivier Pers, DDS, PhD, Divi Cornec, MD, PhD: Université de Bretagne Occidendale, Brest, Bretagne, France
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3
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Berti A, Hillion S, Hummel AM, Son YM, Chriti N, Peikert T, Carmona EM, Abdulahad WH, Heeringa P, Harris KM, St Clair EW, Brunetta P, Fervenza FC, Langford CA, Kallenberg CG, Merkel PA, Monach PA, Seo P, Spiera RF, Stone JH, Grandi G, Sun J, Pers JO, Specks U, Cornec D. Circulating autoreactive proteinase 3+ B cells and tolerance checkpoints in ANCA-associated vasculitis. JCI Insight 2021; 6:150999. [PMID: 34618687 PMCID: PMC8663783 DOI: 10.1172/jci.insight.150999] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 10/06/2021] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Little is known about the autoreactive B cells in antineutrophil cytoplasmic antibody–associated (ANCA-associated) vasculitis (AAV). We aimed to investigate tolerance checkpoints of circulating antigen-specific proteinase 3–reactive (PR3+) B cells. METHODS Multicolor flow cytometry in combination with bioinformatics and functional in vitro studies were performed on baseline samples of PBMCs from 154 well-characterized participants of the RAVE trial (NCT00104299) with severely active PR3-AAV and myeloperoxidase-AAV (MPO-AAV) and 27 healthy controls (HCs). Clinical data and outcomes from the trial were correlated with PR3+ B cells (total and subsets). RESULTS The frequency of PR3+ B cells among circulating B cells was higher in participants with PR3-AAV (4.77% median [IQR, 3.98%–6.01%]) than in participants with MPO-AAV (3.16% median [IQR, 2.51%–5.22%]) and participants with AAV compared with HCs (1.67% median [IQR, 1.27%–2.16%], P < 0.001 for all comparisons), implying a defective central tolerance checkpoint in patients with AAV. Only PBMCs from participants with PR3-AAV contained PR3+ B cells capable of secreting PR3-ANCA IgG in vitro, proving they were functionally distinct from those of participants with MPO-AAV and HCs. Unsupervised clustering identified subtle subsets of atypical autoreactive PR3+ memory B cells accumulating through the maturation process in patients with PR3-AAV. PR3+ B cells were enriched in the memory B cell compartment of participants with PR3-AAV and were associated with higher serum CXCL13 levels, suggesting an increased germinal center activity. PR3+ B cells correlated with systemic inflammation (C-reactive protein and erythrocyte sedimentation rate, P < 0.05) and complete remission (P < 0.001). CONCLUSION This study suggests the presence of defective central antigen-independent and peripheral antigen-dependent checkpoints in patients with PR3-AAV, elucidating the selection process of autoreactive B cells. Trial registration ClinicalTrials.gov NCT00104299. Funding The Vasculitis Foundation, the National Institute of Allergy and Infectious Diseases of the NIH, and the Mayo Foundation for Education and Research.
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Affiliation(s)
- Alvise Berti
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota, USA.,Rheumatology Unit, S. Chiara Regional Hospital and Department of CIBIO, University of Trento, Trento, Italy
| | - Sophie Hillion
- INSERM UMR1227, Lymphocytes B et Autoimmunité, University of Brest, CHRU Brest, Brest, France
| | - Amber M Hummel
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Young Min Son
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota, USA.,Department of Immunology, Mayo Clinic, Rochester, Minnesota, USA
| | - Nedra Chriti
- INSERM UMR1227, Lymphocytes B et Autoimmunité, University of Brest, CHRU Brest, Brest, France
| | - Tobias Peikert
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Eva M Carmona
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota, USA.,Department of Immunology, Mayo Clinic, Rochester, Minnesota, USA
| | - Wayel H Abdulahad
- Department of Rheumatology and Clinical Immunology and Department of Pathology and Medical Biology, University of Groningen, Groningen, Netherlands
| | - Peter Heeringa
- Department of Rheumatology and Clinical Immunology and Department of Pathology and Medical Biology, University of Groningen, Groningen, Netherlands
| | | | - E William St Clair
- Division of Rheumatology, Duke University Medical Center, Durham, North Carolina, USA
| | - Paul Brunetta
- Genentech Inc., South San Francisco, California, USA
| | - Fernando C Fervenza
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Carol A Langford
- Center for Vasculitis Care and Research, Department of Rheumatic and Immunologic Diseases, Cleveland Clinic, Cleveland, Ohio, USA
| | - Cees Gm Kallenberg
- Department of Rheumatology and Clinical Immunology and Department of Pathology and Medical Biology, University of Groningen, Groningen, Netherlands
| | - Peter A Merkel
- Division of Rheumatology, Department of Medicine, Division of Clinical Epidemiology, Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Paul A Monach
- Brigham and Women's Hospital and VA Boston Healthcare System, Boston Massachusetts, USA
| | - Philip Seo
- Division of Rheumatology, Johns Hopkins University, Baltimore, Maryland, USA
| | - Robert F Spiera
- Vasculitis & Scleroderma Program, Hospital for Special Surgery, New York, New York, USA
| | - John H Stone
- Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Guido Grandi
- Rheumatology Unit, S. Chiara Regional Hospital and Department of CIBIO, University of Trento, Trento, Italy
| | - Jie Sun
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota, USA.,Department of Immunology, Mayo Clinic, Rochester, Minnesota, USA
| | - Jacques-Olivier Pers
- INSERM UMR1227, Lymphocytes B et Autoimmunité, University of Brest, CHRU Brest, Brest, France
| | - Ulrich Specks
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Divi Cornec
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota, USA.,INSERM UMR1227, Lymphocytes B et Autoimmunité, University of Brest, CHRU Brest, Brest, France
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4
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Thompson GE, Fussner LA, Hummel AM, Schroeder DR, Silva F, Snyder MR, Langford CA, Merkel PA, Monach PA, Seo P, Spiera RF, St Clair EW, Stone JH, Specks U. Clinical Utility of Serial Measurements of Antineutrophil Cytoplasmic Antibodies Targeting Proteinase 3 in ANCA-Associated Vasculitis. Front Immunol 2020; 11:2053. [PMID: 33013868 PMCID: PMC7495134 DOI: 10.3389/fimmu.2020.02053] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 07/28/2020] [Indexed: 11/13/2022] Open
Abstract
Background: The utility of ANCA testing as an indicator of disease activity in ANCA-associated vasculitis (AAV) remains controversial. This study aimed to determine the association of ANCA testing by various methods and subsequent remission and examine the utility of a widely used automated addressable laser-bead immunoassay (ALBIA) to predict disease relapses. Methods: Data from the Rituximab vs. Cyclophosphamide for ANCA-Associated Vasculitis (RAVE) trial were used. ANCA testing was performed by direct ELISA, capture ELISA, and ALBIA. Cox proportional hazards regression models were used to evaluate the association of PR3-ANCA level and subsequent remission or relapse. The ALBIA results are routinely reported as >8 when the value is high. For this study, samples were further titrated. A decrease and increase in PR3-ANCA were defined as a halving or doubling in value, respectively. Results: A decrease in ANCA by ALBIA at 2 months was associated with shorter time to sustained remission (HR 4.52, p = 0.035). A decrease in ANCA by direct ELISA at 4 months was associated with decreased time to sustained remission (HR 1.77, p = 0.050). There were no other associations between ANCA decreases or negativity and time to remission. An increase in PR3-ANCA by ALBIA was found in 78 of 93 subjects (84%). Eleven (14%) had a PR3-ANCA value which required titration for detection of an increase. An increase of ANCA by ALBIA was associated with severe relapse across various subgroups. Conclusions: A decrease in ANCA by ALBIA at 2 months and by direct ELISA at 4 months may be predictive of subsequent remission. These results should be confirmed in a separate cohort with similarly protocolized sample and clinical data collection. A routinely used automated ALBIA for PR3-ANCA measurement is comparable to direct ELISA in predicting relapse in PR3-AAV. Without titration, 14% of the increases detected by ALBIA would have been missed. Titration is recommended when this assay is used for disease monitoring. The association of an increase in PR3-ANCA with the risk of subsequent relapse remains complex and is affected by disease phenotype and remission induction agent.
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Affiliation(s)
- Gwen E Thompson
- Essentia Health, Division of Pulmonary and Critical Care, Fargo, ND, United States.,Mayo Clinic and Mayo Foundation for Research and Education, Rochester, MN, United States
| | - Lynn A Fussner
- Division of Pulmonary, Critical Care, and Sleep Medicine, The Ohio State University, Columbus, OH, United States
| | - Amber M Hummel
- Mayo Clinic and Mayo Foundation for Research and Education, Rochester, MN, United States
| | - Darrell R Schroeder
- Mayo Clinic and Mayo Foundation for Research and Education, Rochester, MN, United States
| | - Francisco Silva
- Department of Rheumatology, Facultad de Medicina Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Melissa R Snyder
- Mayo Clinic and Mayo Foundation for Research and Education, Rochester, MN, United States
| | - Carol A Langford
- Cleveland Clinic, Division of Rheumatology, Cleveland, OH, United States
| | - Peter A Merkel
- Division of Rheumatology, Department of Medicine, University of Pennsylvania, Philadelphia, PA, United States.,Division of Clinical Epidemiology, Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, PA, United States
| | - Paul A Monach
- Division of Rheumatology, Brigham and Women's Hospital, Boston, MA, United States
| | - Philip Seo
- Division of Rheumatology, Johns Hopkins University, Baltimore, MD, United States
| | - Robert F Spiera
- Division of Rheumatology, Hospital for Special Surgery, New York, NY, United States
| | | | - John H Stone
- Division of Rheumatology, Massachusetts General Hospital, Boston, MA, United States
| | - Ulrich Specks
- Mayo Clinic and Mayo Foundation for Research and Education, Rochester, MN, United States
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5
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Pang YP, Casal Moura M, Thompson GE, Nelson DR, Hummel AM, Jenne DE, Emerling D, Volkmuth W, Robinson WH, Specks U. Remote Activation of a Latent Epitope in an Autoantigen Decoded With Simulated B-Factors. Front Immunol 2019; 10:2467. [PMID: 31708920 PMCID: PMC6823208 DOI: 10.3389/fimmu.2019.02467] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 10/03/2019] [Indexed: 11/13/2022] Open
Abstract
Mutants of a catalytically inactive variant of Proteinase 3 (PR3)—iPR3-Val103 possessing a Ser195Ala mutation relative to wild-type PR3-Val103—offer insights into how autoantigen PR3 interacts with antineutrophil cytoplasmic antibodies (ANCAs) in granulomatosis with polyangiitis (GPA) and whether such interactions can be interrupted. Here we report that iHm5-Val103, a triple mutant of iPR3-Val103, bound a monoclonal antibody (moANCA518) from a GPA patient on an epitope remote from the mutation sites, whereas the corresponding epitope of iPR3-Val103 was latent to moANCA518. Simulated B-factor analysis revealed that the binding of moANCA518 to iHm5-Val103 was due to increased main-chain flexibility of the latent epitope caused by remote mutations, suggesting rigidification of epitopes with therapeutics to alter pathogenic PR3·ANCA interactions as new GPA treatments.
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Affiliation(s)
- Yuan-Ping Pang
- Computer-Aided Molecular Design Laboratory, Mayo Clinic, Rochester, MN, United States
| | - Marta Casal Moura
- Thoracic Disease Research Unit, Mayo Clinic, Rochester, MN, United States
| | - Gwen E Thompson
- Thoracic Disease Research Unit, Mayo Clinic, Rochester, MN, United States
| | - Darlene R Nelson
- Thoracic Disease Research Unit, Mayo Clinic, Rochester, MN, United States
| | - Amber M Hummel
- Thoracic Disease Research Unit, Mayo Clinic, Rochester, MN, United States
| | - Dieter E Jenne
- Comprehensive Pneumology Center, Helmholtz Zentrum München & Max-Planck Institute for Neuroimmunology, Martinsried, Germany
| | | | | | - William H Robinson
- Department of Medicine, Stanford University, Palo Alto, CA, United States
| | - Ulrich Specks
- Thoracic Disease Research Unit, Mayo Clinic, Rochester, MN, United States
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6
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Sethi S, Madden BJ, Debiec H, Charlesworth MC, Gross L, Ravindran A, Hummel AM, Specks U, Fervenza FC, Ronco P. Exostosin 1/Exostosin 2-Associated Membranous Nephropathy. J Am Soc Nephrol 2019; 30:1123-1136. [PMID: 31061139 DOI: 10.1681/asn.2018080852] [Citation(s) in RCA: 169] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 03/24/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND In membranous nephropathy (MN), which is characterized by deposition of immune complexes along the glomerular basement membrane (GBM), phospholipase A2 receptor (PLA2R) and thrombospondin type 1 domain-containing 7A are target antigens in approximately 70% and 1%-5% of cases of primary MN, respectively. In other cases of primary MN and in secondary MN, the target antigens are unknown. METHODS We studied 224 cases of biopsy-proven PLA2R-negative MN and 102 controls (including 47 cases of PLA2R-associated MN) in pilot and discovery cohorts. We also evaluated 48 cases of PLA2R-negative presumed primary MN and lupus MN in a validation cohort. We used laser microdissection and mass spectrometry to identify new antigens, which were localized by immunohistochemistry. RESULTS Mass spectrometry detected exostosin 1 (EXT1) and exostosin 2 (EXT2) in 21 cases of PLA2R-negative MN, but not in PLA2R-associated MN and control cases. Immunohistochemistry staining revealed bright granular GBM staining for EXT1 and EXT2. Clinical and biopsy findings showed features of autoimmune disease, including lupus, in 80.7% of the 26 EXT1/EXT2-associated MN cases we identified. In the validation cohort, we confirmed that EXT1/EXT2 staining was detected in pure class 5 lupus nephritis (eight of 18 patients) and in presumed primary MN associated with signs of autoimmunity (three of 16 patients); only one of the 14 cases of mixed class 5 and 3/4 lupus nephritis was positive for EXT1/EXT2. Tests in seven patients with EXT1/EXT2-associated MN found no circulating anti-exostosin antibodies. CONCLUSIONS A subset of MN is associated with accumulation of EXT1 and EXT2 in the GBM. Autoimmune disease is common in this group of patients.
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Affiliation(s)
| | | | - Hanna Debiec
- Sorbonne Université, Université Pierre et Marie Curie Paris 06, and Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche S1155, Paris, France; and
| | | | | | | | | | - Ulrich Specks
- Divisions of Pulmonary and Critical Care Medicine and
| | | | - Pierre Ronco
- Sorbonne Université, Université Pierre et Marie Curie Paris 06, and Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche S1155, Paris, France; and.,Department of Nephrology and Dialysis, Assistance Publique-Hôpitaux de Paris, Tenon Hospital, Paris, France
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7
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Schieppati F, Gregorini G, Hummel AM, D'Adda M, Borlenghi E, Lamorgese C, Specks U, Rossi G. Acquired cyclic neutropenia associated with cocaine-induced anti-neutrophil cytoplasmic antibodies binding to human neutrophil elastase. Am J Hematol 2018; 93:E227-E229. [PMID: 29999538 DOI: 10.1002/ajh.25197] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 06/09/2018] [Accepted: 06/11/2018] [Indexed: 11/10/2022]
Affiliation(s)
| | - Gina Gregorini
- Department of Nephrology; ASST Spedali Civili di Brescia; Brescia Italy
| | - Amber M. Hummel
- Division of Pulmonary and Critical Care Medicine; Mayo Clinic; Rochester Minnesota
| | - Mariella D'Adda
- Department of Hematology; ASST Spedali Civili di Brescia; Brescia Italy
| | - Erika Borlenghi
- Department of Hematology; ASST Spedali Civili di Brescia; Brescia Italy
| | - Cinzia Lamorgese
- Department of Hematology; ASST Spedali Civili di Brescia; Brescia Italy
| | - Ulrich Specks
- Division of Pulmonary and Critical Care Medicine; Mayo Clinic; Rochester Minnesota
| | - Giuseppe Rossi
- Department of Hematology; ASST Spedali Civili di Brescia; Brescia Italy
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8
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Cornec D, Kabat BF, Mills JR, Cheu M, Hummel AM, Schroeder DR, Cascino MD, Brunetta P, Murray DL, Snyder MR, Fervenza F, Hoffman GS, Kallenberg CGM, Langford CA, Merkel PA, Monach PA, Seo P, Spiera RF, St Clair EW, Stone JH, Barnidge DR, Specks U. Pharmacokinetics of rituximab and clinical outcomes in patients with anti-neutrophil cytoplasmic antibody associated vasculitis. Rheumatology (Oxford) 2018; 57:639-650. [PMID: 29340623 PMCID: PMC5888934 DOI: 10.1093/rheumatology/kex484] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 11/10/2017] [Indexed: 12/16/2022] Open
Abstract
Objectives To study the determinants of the pharmacokinetics (PK) of rituximab (RTX) in patients with ANCA-associated vasculitis (AAV) and its association with clinical outcomes. Methods This study included data from 89 patients from the RTX in AAV trial who received the full dose of RTX (four weekly infusions of 375 mg/m2). RTX was quantified at weeks 2, 4, 8, 16 and 24, and summarized by computing the trapezoidal area under the curve. We explored potential determinants of the PK-RTX, and analysed its association with clinical outcomes: achievement of remission at 6 months, duration of B-cell depletion and time to relapse in patients who achieved complete remission. Results RTX serum levels were significantly lower in males and in newly diagnosed patients, and negatively correlated with body surface area, baseline B-cell count and degree of disease activity. In multivariate analyses, the main determinants of PK-RTX were sex and new diagnosis. Patients reaching complete remission at month 6 had similar RTX levels compared with patients who did not reach complete remission. Patients with higher RTX levels generally experienced longer B-cell depletion than patients with lower levels, but RTX levels at the different time points and area under the curve were not associated with time to relapse. Conclusion Despite the body-surface-area-based dosing protocol, PK-RTX is highly variable among patients with AAV, its main determinants being sex and newly diagnosed disease. We did not observe any relevant association between PK-RTX and clinical outcomes. The monitoring of serum RTX levels does not seem clinically useful in AAV.
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Affiliation(s)
- Divi Cornec
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN, USA
- Rheumatology Department, Brest University Hospital, and INSERM U1227, Brest, France
| | - Brian F Kabat
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN
| | - John R Mills
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | | | - Amber M Hummel
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN, USA
| | | | | | | | - David L Murray
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | - Melissa R Snyder
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | | | - Gary S Hoffman
- Division of Rheumatology, Cleveland Clinic Foundation, Cleveland, OH, USA
| | | | - Carol A Langford
- Division of Rheumatology, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Peter A Merkel
- Division of Rheumatology and Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, PA
| | - Paul A Monach
- Rheumatology, Boston University Medical Center, Boston, MA
| | - Philip Seo
- Rheumatology, Johns Hopkins University, Baltimore, MD
| | | | | | - John H Stone
- Rheumatology, Massachusetts General Hospital, Boston, MA, USA
| | - David R Barnidge
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | - Ulrich Specks
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN, USA
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9
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Fussner LA, Hummel AM, Schroeder DR, Silva F, Cartin-Ceba R, Snyder MR, Hoffman GS, Kallenberg CGM, Langford CA, Merkel PA, Monach PA, Seo P, Spiera RF, William St Clair E, Tchao NK, Stone JH, Specks U. Factors Determining the Clinical Utility of Serial Measurements of Antineutrophil Cytoplasmic Antibodies Targeting Proteinase 3. Arthritis Rheumatol 2017; 68:1700-10. [PMID: 26882078 DOI: 10.1002/art.39637] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 02/09/2016] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Relapse following remission is common in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), particularly with ANCAs directed at proteinase 3 (PR3). This study was undertaken to evaluate the association of an increase in PR3-ANCA level with subsequent relapse. METHODS Data from the Rituximab versus Cyclophosphamide for ANCA-Associated Vasculitis (RAVE) trial were used. Starting from the time of achieving complete remission, serial measurements by direct and capture enzyme-linked immunosorbent assays (ELISAs) were analyzed in 93 patients with PR3-ANCA, using Cox proportional hazards regression. RESULTS An increase in PR3-ANCA level was identified in 58 of 93 subjects (62.4%) by direct ELISA and in 59 of 93 (63.4%) by capture ELISA. Relapses occurred in 55 of 93 subjects (59.1%), with 25 and 21 occurring within 1 year after an increase by direct ELISA and capture ELISA, respectively. An increase by direct ELISA was associated with subsequent severe relapses (hazard ratio [HR] 4.57; P < 0.001), particularly in patients presenting with renal involvement (HR 7.94; P < 0.001) and alveolar hemorrhage (HR 24.19; P < 0.001). Both assays identified increased risk for severe relapse in the rituximab group (HR 5.80; P = 0.002 for direct ELISA and HR 4.54; P = 0.007 for capture ELISA) but not the cyclophosphamide/azathioprine group (P = 0.103 and P = 0.197, respectively). CONCLUSION The association of an increase in PR3-ANCA level with the risk of subsequent relapse is partially affected by the PR3-ANCA detection methodology, disease phenotype, and remission induction treatment. An increase in PR3-ANCA level during complete remission conveys an increased risk of relapse, particularly severe relapse, among patients with renal involvement or alveolar hemorrhage and those treated with rituximab. Serial measurements of PR3-ANCA may be informative in this subset of patients, but the risk of relapse must be weighed carefully against the risks associated with therapy.
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Affiliation(s)
- Lynn A Fussner
- Mayo Clinic and Mayo Foundation for Medical Education and Research, Rochester, Minnesota
| | - Amber M Hummel
- Mayo Clinic and Mayo Foundation for Medical Education and Research, Rochester, Minnesota
| | - Darrell R Schroeder
- Mayo Clinic and Mayo Foundation for Medical Education and Research, Rochester, Minnesota
| | | | - Rodrigo Cartin-Ceba
- Mayo Clinic and Mayo Foundation for Medical Education and Research, Rochester, Minnesota
| | - Melissa R Snyder
- Mayo Clinic and Mayo Foundation for Medical Education and Research, Rochester, Minnesota
| | | | | | | | | | - Paul A Monach
- Boston University, Boston University Medical Center, and VA Boston Healthcare System, Boston, Massachusetts
| | - Philip Seo
- Johns Hopkins University, Baltimore, Maryland
| | | | | | | | - John H Stone
- Massachusetts General Hospital, Boston, Massachusetts
| | - Ulrich Specks
- Mayo Clinic and Mayo Foundation for Medical Education and Research, Rochester, Minnesota
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10
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Clain JM, Hummel AM, Stone JH, Fervenza FC, Hoffman GS, Kallenberg CGM, Langford CA, McCune WJ, Merkel PA, Monach PA, Seo P, Spiera RF, St Clair EW, Ytterberg SR, Specks U. Immunoglobulin (Ig)M antibodies to proteinase 3 in granulomatosis with polyangiitis and microscopic polyangiitis. Clin Exp Immunol 2017; 188:174-181. [PMID: 28076879 DOI: 10.1111/cei.12925] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2017] [Indexed: 01/12/2023] Open
Abstract
Anti-neutrophil cytoplasmic antibodies (ANCA) appear to play an important role in the pathogenesis of ANCA-associated vasculitis (AAV). However, ANCA alone are not sufficient to generate disease, and some evidence suggests that infectious triggers may serve as inciting events for AAV disease activity. Antibodies of the immunoglobulin (Ig)M isotype often serve as markers of recent infection, and IgM ANCA have been identified previously in patients with AAV, although the frequency and clinical relevance of IgM ANCA is not well established. We sought to characterize IgM ANCA more clearly by creating a novel enzyme-linked immunosorbent assay (ELISA) for IgM antibodies to proteinase 3 [IgM proteinase 3 (PR3)-ANCA], which we applied to two large, clinically well-characterized trial cohorts of patients with granulomatosis with polyangiitis and microscopic polyangiitis. In the first cohort, IgM PR3-ANCA occurred with a frequency of 15·0%, and were associated with a higher degree of disease severity and a trend towards a higher rate of alveolar haemorrhage (29·6 versus 15·7%, P = 0·10). Analysis of follow-up samples in this cohort showed that the presence of IgM PR3-ANCA was transient, but could recur. In the second cohort, IgM PR3-ANCA occurred with a frequency of 41·1%, and were also associated with a higher degree of disease severity. A higher rate of alveolar haemorrhage was observed among those with IgM PR3-ANCA (45·3 versus 15·8%; P < 0·001). The association of transient IgM PR3-ANCA with an acute respiratory manifestation of AAV suggests a possible link between an infectious trigger and AAV disease activity.
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Affiliation(s)
- J M Clain
- Mayo Clinic and Foundation, Rochester, MN, USA
| | - A M Hummel
- Mayo Clinic and Foundation, Rochester, MN, USA
| | - J H Stone
- Massachusetts General Hospital, Boston, MA, USA
| | | | - G S Hoffman
- Cleveland Clinic Foundation, Cleveland, OH, USA
| | | | | | - W J McCune
- University of Michigan, Ann Arbor, MI, USA
| | - P A Merkel
- University of Pennsylvania, Philadelphia, PA, USA
| | - P A Monach
- Boston University Medical Center, Boston, MA, USA
| | - P Seo
- Johns Hopkins University, Baltimore, MD, USA
| | - R F Spiera
- Hospital for Special Surgery, New York, NY, USA
| | | | | | - U Specks
- Mayo Clinic and Foundation, Rochester, MN, USA
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11
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Mills JR, Cornec D, Dasari S, Ladwig PM, Hummel AM, Cheu M, Murray DL, Willrich MA, Snyder MR, Hoffman GS, Kallenberg CGM, Langford CA, Merkel PA, Monach PA, Seo P, Spiera RF, St Clair EW, Stone JH, Specks U, Barnidge DR. Using Mass Spectrometry to Quantify Rituximab and Perform Individualized Immunoglobulin Phenotyping in ANCA-Associated Vasculitis. Anal Chem 2016; 88:6317-25. [PMID: 27228216 DOI: 10.1021/acs.analchem.6b00544] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Therapeutic monoclonal immunoglobulins (mAbs) are used to treat patients with a wide range of disorders including autoimmune diseases. As pharmaceutical companies bring more fully humanized therapeutic mAb drugs to the healthcare market analytical platforms that perform therapeutic drug monitoring (TDM) without relying on mAb specific reagents will be needed. In this study we demonstrate that liquid-chromatography-mass spectrometry (LC-MS) can be used to perform TDM of mAbs in the same manner as smaller nonbiologic drugs. The assay uses commercially available reagents combined with heavy and light chain disulfide bond reduction followed by light chain analysis by microflow-LC-electrospray ionization-quadrupole-time-of-flight mass spectrometry (ESI-Q-TOF MS). Quantification is performed using the peak areas from multiply charged mAb light chain ions using an in-house developed software package developed for TDM of mAbs. The data presented here demonstrate the ability of an LC-MS assay to quantify a therapeutic mAb in a large cohort of patients in a clinical trial. The ability to quantify any mAb in serum via the reduced light chain without the need for reagents specific for each mAb demonstrates the unique capabilities of LC-MS. This fact, coupled with the ability to phenotype a patient's polyclonal repertoire in the same analysis further shows the potential of this approach to mAb analysis.
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Affiliation(s)
- John R Mills
- Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Divi Cornec
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic , Rochester, Minnesota 55905, United States.,Rheumatology Department, Brest University Hospital , 29609 Brest, Cedex, France
| | - Surendra Dasari
- Department of Health Sciences Research, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Paula M Ladwig
- Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Amber M Hummel
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Melissa Cheu
- Genentech Inc. , South San Francisco, California 94080, United States
| | - David L Murray
- Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Maria A Willrich
- Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Melissa R Snyder
- Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - Gary S Hoffman
- Cleveland Clinic Foundation , Cleveland, Ohio 44195, United States
| | | | - Carol A Langford
- Cleveland Clinic Foundation , Cleveland, Ohio 44195, United States
| | - Peter A Merkel
- University of Pennsylvania , Philadelphia, Pennsylvania 19104, United States
| | - Paul A Monach
- Boston University Medical Center , Boston, Massachusetts 02115, United States
| | - Philip Seo
- Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Robert F Spiera
- Hospital for Special Surgery , New York, New York 10021, United States
| | | | - John H Stone
- Massachusetts General Hospital , Boston, Massachusetts 02114, United States
| | - Ulrich Specks
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic , Rochester, Minnesota 55905, United States
| | - David R Barnidge
- Department of Laboratory Medicine and Pathology, Mayo Clinic , Rochester, Minnesota 55905, United States
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12
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Hinkofer LC, Seidel SAI, Korkmaz B, Silva F, Hummel AM, Braun D, Jenne DE, Specks U. A monoclonal antibody (MCPR3-7) interfering with the activity of proteinase 3 by an allosteric mechanism. J Biol Chem 2013; 288:26635-48. [PMID: 23902773 DOI: 10.1074/jbc.m113.495770] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proteinase 3 (PR3) is an abundant serine protease of neutrophil granules and a major target of autoantibodies (PR3 anti-neutrophil cytoplasmic antibodies) in granulomatosis with polyangiitis. Some of the PR3 synthesized by promyelocytes in the bone marrow escapes the targeting to granules and occurs on the plasma membrane of naive and primed neutrophils. This membrane-associated PR3 antigen may represent pro-PR3, mature PR3, or both forms. To discriminate between mature PR3 and its inactive zymogen, which have different conformations, we generated and identified a monoclonal antibody called MCPR3-7. It bound much better to pro-PR3 than to mature PR3. This monoclonal antibody greatly reduced the catalytic activity of mature PR3 toward extended peptide substrates. Using diverse techniques and multiple recombinant PR3 variants, we characterized its binding properties and found that MCPR3-7 preferentially bound to the so-called activation domain of the zymogen and changed the conformation of mature PR3, resulting in impaired catalysis and inactivation by α1-proteinase inhibitor (α1-antitrypsin). Noncovalent as well as covalent complexation between PR3 and α1-proteinase inhibitor was delayed in the presence of MCPR3-7, but cleavage of certain thioester and paranitroanilide substrates with small residues in the P1 position was not inhibited. We conclude that MCPR3-7 reduces PR3 activity by an allosteric mechanism affecting the S1' pocket and further prime side interactions with substrates. In addition, MCPR3-7 prevents binding of PR3 to cellular membranes. Inhibitory antibodies targeting the activation domain of PR3 could be exploited as highly selective inhibitors of PR3, scavengers, and clearers of the PR3 autoantigen in granulomatosis with polyangiitis.
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Affiliation(s)
- Lisa C Hinkofer
- From the Comprehensive Pneumology Center, Institute of Lung Biology and Disease (iLBD), University Hospital, Ludwig Maximilians University and Helmholtz Zentrum München, Member of the German Center for Lung Research (DZL), Max-Lebsche-Platz 31, 81377 Munich, Germany
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13
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Silva F, Hummel AM, Jenne DE, Specks U. Discrimination and variable impact of ANCA binding to different surface epitopes on proteinase 3, the Wegener's autoantigen. J Autoimmun 2011; 35:299-308. [PMID: 20810247 DOI: 10.1016/j.jaut.2010.06.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 06/03/2010] [Accepted: 06/07/2010] [Indexed: 11/28/2022]
Abstract
Proteinase 3 (PR3)-specific antineutrophil cytoplasmic antibodies (ANCA) are highly specific for the autoimmune small vessel vasculitis, Wegener's granulomatosis (WG). PR3-ANCA have proven diagnostic value but their pathogenic potential and utility as a biomarker for disease activity remain unclear. PR3-ANCA recognize conformational epitopes, and epitope-specific PR3-ANCA subsets with variable impact on biological functions of PR3 have been postulated. The aims of this study were to identify specific PR3 surface epitopes recognized by monoclonal antibodies (moAbs) and to determine whether the findings can be used to measure the functional impact of epitope-specific PR3-ANCA and their potential relationship to disease activity. We used a novel flow cytometry assay based on TALON-beads coated with recombinant human (H) and murine (M) PR3 and 10 custom-designed chimeric human/mouse rPR3-variants (Hm1-5/Mh1-5) identifying 5 separate non-conserved PR3 surface epitopes. Anti-PR3 moAbs recognize 4 major surface epitopes, and we identified the specific surface location of 3 of these with the chimeric rPR3-variants. The ability of PR3-ANCA to inhibit the enzymatic activity of PR3 was measured indirectly using a capture-ELISA system based on the different epitopes recognized by capturing moAbs. Epitope-specific PR3-ANCA capture-ELISA results obtained from patient plasma (n=27) correlated with the inhibition of enzymatic activity of PR3 by paired IgG preparations (r=0.7, P<0.01). The capture-ELISA results also seem to reflect disease activity. In conclusion, insights about epitopes recognized by anti-PR3 moAbs can be applied to separate PR3-ANCA subsets with predictable functional qualities. The ability of PR3-ANCA to inhibit the enzymatic activity of PR3, a property linked to disease activity, can now be gauged using a simple epitope-based capture-ELISA system.
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Affiliation(s)
- Francisco Silva
- Thoracic Diseases Research Unit, Stabile Bldg. 8-56, Division of Pulmonary and Critical Care Medicine, Mayo Clinic and Foundation, 200 First Street SW, Rochester, MN 55905, USA
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14
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Finkielman JD, Merkel PA, Schroeder D, Hoffman GS, Spiera R, St Clair EW, Davis JC, McCune WJ, Lears A, Ytterberg SR, Hummel AM, Viss MA, Peikert T, Stone JH, Specks U. Glycosylation of proteinase 3 (PR3) is not required for its reactivity with antineutrophil cytoplasmic antibodies (ANCA) in Wegener's granulomatosis. Clin Exp Rheumatol 2009; 27:S45-S52. [PMID: 19646346 PMCID: PMC3183098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
OBJECTIVE The glycosylation status of autoantigens appears to be crucial for the pathogenesis of some autoimmune diseases, since carbohydrates play a crucial role in the distinction of self from non-self. Proteinase 3 (PR3), the main target antigen for anti-neutrophil cytoplasmic antibodies (ANCA) in patients with Wegener's granulomatosis (WG), contains two Asn-linked glycosylation sites. The present study explores the influence of the glycosylation status of PR3 on the PR3 recognition by ANCA in a well characterized population of patients with WG. METHODS Forty-four patients with WG (459 serum samples) who participated in a multicenter randomized trial, were tested by capture ELISA for ANCA against PR3 and deglycosylated recombinant variants of PR3. RESULTS The patients were followed for a median of 27 months, and the median number of serum samples per patient was 10. At baseline, the correlation between the levels of ANCA against PR3 and against all the deglycosylated recombinant variants of PR3 were greater than 0.94 (?<0.001 for all the comparisons). Longitudinal analyses comparing the levels of ANCA against PR3 versus all the deglycosylated recombinant variants of PR3, using linear mixed models, showed no significant statistical differences (rho >or=0.90 in all cases). CONCLUSION The glycosylation status of PR3 has no impact on its recognition by ANCA in WG.
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Affiliation(s)
- J D Finkielman
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN, USA
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15
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Peikert T, Finkielman JD, Hummel AM, McKenney ME, Gregorini G, Trimarchi M, Specks U. Functional characterization of antineutrophil cytoplasmic antibodies in patients with cocaine-induced midline destructive lesions. ACTA ACUST UNITED AC 2008; 58:1546-51. [PMID: 18438818 DOI: 10.1002/art.23469] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE Antineutrophil cytoplasmic antibodies (ANCA) binding to neutrophil elastase (NE) and proteinase 3 (PR3) are detectable in most patients with cocaine-induced midline destructive lesions (CIMDL), but the pathogenic role and antigen specificity of these antibodies are unknown. This study was undertaken to assess the effects of NE ANCA on the enzymatic activity of NE, to determine whether these antibodies interfere with the physiologic effect of secretory leukoprotease inhibitor (SLPI), and to investigate the antigen specificity of both NE and PR3 ANCA in patients with CIMDL. We also compared the binding of PR3 ANCA in patients with CIMDL with that in patients with Wegener's granulomatosis (WG). METHODS PR3 ANCA and NE ANCA were detected by capture enzyme-linked immunosorbent assays (ELISAs) and by indirect immunofluorescence. IgG was purified from the patients' sera, and the influence of NE ANCA on the enzymatic activity of NE and on the inhibitory activity of SLPI was investigated by determining the hydrolysis of N-methoxysuccinyl-Ala-Ala-Pro-Val p-nitroanilide by NE. RESULTS IgG from NE ANCA-positive sera of patients with CIMDL inhibited the enzymatic activity of NE and did not interfere with the activity of SLPI. In contrast to the findings in WG sera, measurement of PR3 ANCA in CIMDL sera showed only fair to moderate concordance between the 2 different capture ELISAs. Cross-inhibition experiments demonstrated that NE ANCA and PR3 ANCA represent distinct autoantibodies in patients with CIMDL. CONCLUSION The functional effects of NE ANCA on the enzymatic activity of NE or on the activity of SLPI cannot be implicated in the pathogenesis of CIMDL. The autoimmune reaction that targets neutrophil serine proteases in patients with CIMDL is frequently directed against more than one antigen. The ANCA response, including the reactivity of PR3 ANCA, in patients with CIMDL differs from what has been described in patients with WG.
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Affiliation(s)
- Tobias Peikert
- Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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16
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Finkielman JD, Merkel PA, Schroeder D, Hoffman GS, Spiera R, St Clair EW, Davis JC, McCune WJ, Lears AK, Ytterberg SR, Hummel AM, Viss MA, Peikert T, Stone JH, Specks U. Antiproteinase 3 antineutrophil cytoplasmic antibodies and disease activity in Wegener granulomatosis. Ann Intern Med 2007; 147:611-9. [PMID: 17975183 DOI: 10.7326/0003-4819-147-9-200711060-00005] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND The utility of antineutrophil cytoplasmic antibody (ANCA) levels to guide the management of patients with Wegener granulomatosis remains controversial. OBJECTIVE To determine whether pro-proteinase 3 (PR3)-ANCA levels are a better measure of disease activity than mature-PR3-ANCA levels, whether decreases in either level are associated with shorter time to remission, and whether increases are followed by relapse. DESIGN Prospective, observational cohort study. SETTING 8 United States medical centers that participated in a treatment trial for Wegener granulomatosis. PATIENTS 156 patients with Wegener granulomatosis enrolled during periods of active disease. MEASUREMENTS PR3-ANCA levels (by capture enzyme-linked immunosorbent assay) and disease activity (by the Birmingham Vasculitis Activity Score for Wegener granulomatosis). RESULTS The ANCA levels were only weakly associated with disease activity across patients. The longitudinal association within patients was stronger, but changes in ANCA levels explained less than 10% of the variation in disease activity. Decreases in mature- and pro-PR3-ANCA levels were not statistically significantly associated with shorter time to remission, and increases in mature-PR3-ANCA levels (adjusted hazard ratio, 0.8 [95% CI, 0.4 to 1.9]; P = 0.67) and pro-PR3-ANCA levels (adjusted hazard ratio, 1.0 [CI, 0.5 to 2.1]; P = 0.99) were not associated with relapse. The proportion of patients who had relapse within 1 year of an increase in PR3-ANCA levels was 40% for mature-PR3 (CI, 18% to 56%) and 43% for pro-PR3 (CI, 22% to 58%). LIMITATIONS Samples were collected approximately every 3 months. Sensitivity and specificity of ANCA levels for detecting remission and relapse could not be calculated because each patient had different follow-up times. CONCLUSION Pro-PR3-ANCA is no better than mature-PR3-ANCA as a measure of Wegener granulomatosis activity. Decreases in PR3-ANCA levels are not associated with shorter time to remission, and increases are not associated with relapse. These findings suggest that ANCA levels cannot be used to guide immunosuppressive therapy.
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17
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Finkielman JD, Lee AS, Hummel AM, Viss MA, Jacob GL, Homburger HA, Peikert T, Hoffman GS, Merkel PA, Spiera R, St Clair EW, Davis JC, McCune WJ, Tibbs AK, Ytterberg SR, Stone JH, Specks U. ANCA are detectable in nearly all patients with active severe Wegener's granulomatosis. Am J Med 2007; 120:643.e9-14. [PMID: 17602941 DOI: 10.1016/j.amjmed.2006.08.016] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 06/23/2006] [Accepted: 08/02/2006] [Indexed: 11/15/2022]
Abstract
BACKGROUND The pathogenic significance of antineutrophilic cytoplasmic antibodies (ANCA) in Wegener's granulomatosis is controversial. Their presence is influenced by the extent, severity, and activity of the disease at the time of sampling. The objective of this study was to determine the frequency of ANCA in patients with active Wegener's granulomatosis and to assess the influence of disease severity on test results. METHODS Baseline serum samples from the 180 participants in a multicentric prospective trial were tested for ANCA by indirect immunofluorescence, direct enzyme-linked immunosorbent assay (ELISA), and capture ELISA. Disease activity was measured using the Birmingham Vasculitis Activity Score for Wegener's granulomatosis. All patients had active disease at enrollment. Patients were categorized as having severe (n=128) or limited (n=52) Wegener's granulomatosis. RESULTS When all ANCA detection methods were combined, 166 patients (92%) were ANCA positive, including 96% with severe disease and 83% with limited disease. CONCLUSION ANCA are detectable in nearly all patients with active severe Wegener's granulomatosis, but approximately 1 of 5 patients with active limited disease are ANCA negative. Immunofluorescence and both direct and capture ELISAs are required for optimal detection, suggesting that ANCA are not recognized equally well by all testing methods.
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Affiliation(s)
- Javier D Finkielman
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic and Foundation, Rochester, Minn 55905, USA
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Lee AS, Finkielman JD, Peikert T, Hummel AM, Viss MA, Jacob GL, Homburger HA, Specks U. Agreement of anti-neutrophil cytoplasmic antibody measurements obtained from serum and plasma. Clin Exp Immunol 2006; 146:15-20. [PMID: 16968393 PMCID: PMC1809725 DOI: 10.1111/j.1365-2249.2006.03179.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Serum and plasma are used interchangeably to measure anti-neutrophil cytoplasmic antibodies (ANCA), even though the release of ANCA target antigens during the preparation of serum could affect ANCA assays and cause discrepancies between the results obtained from serum and plasma. To what extent ANCA test results obtained from serum agree and correlate with results from plasma remains unknown. Therefore, a comprehensive comparison was performed using serum and plasma samples which were collected in 175 patients with active Wegener's granulomatosis at enrollment of a recent randomized trial. These paired serum and plasma samples were subjected to parallel ANCA testing by standard indirect immunofluorescence on ethanol-fixed neutrophils, a direct enzyme-linked immunoassay (ELISA) for proteinase 3 (PR3)-ANCA and myeloperoxidase (MPO)-ANCA, and two different capture ELISAs for PR3-ANCA. The concordance of categorical serum and plasma ANCA results was assessed using kappa-coefficients. These were > 0.8 for all assays, indicating a very good concordance between positive and negative serum and plasma results. Spearman's correlation coefficients for serum and plasma PR3-ANCA values obtained by direct ELISA and both capture ELISAs were > or = 0.95 (P < 0.0001). Our study shows that serum and plasma samples can be used interchangeably for measuring ANCA.
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Affiliation(s)
- A S Lee
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic and Foundation, Rochester, MN 55905, USA
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19
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Specks U, Fass DN, Finkielman JD, Hummel AM, Viss MA, Litwiller RD, McDonald CJ. Functional Significance of Asn-linked Glycosylation of Proteinase 3 for Enzymatic Activity, Processing, Targeting, and Recognition by Anti-neutrophil Cytoplasmic Antibodies. J Biochem 2006; 141:101-12. [PMID: 17158864 DOI: 10.1093/jb/mvm008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Proteinase 3 (PR3) is a neutral serine protease stored in neutrophil granules. It has substantial sequence homology with elastase, cathepsin G and azurocidin. PR3 is the target antigen for autoantibodies (ANCA) in Wegener's granulomatosis, a necrotizing vasculitis syndrome. ANCA have been implicated in the pathogenesis of this disease. PR3 has two potential Asn-linked glycosylation sites. This study was designed to determine the occupancy of these glycosylation sites, and to evaluate their effect on enzymatic function, intracellular processing, targeting to granules and recognition by ANCA. We found that glycosylation occurs at both sites in native neutrophil PR3 and in wild type recombinant PR3 (rPR3) expressed in HMC-1 cells. Using glycosylation deficient rPR3 mutants we found that glycosylation at Asn-147, but not at Asn-102, is critical for thermal stability, and for optimal hydrolytic activity of PR3. Efficient amino-terminal proteolytic processing of rPR3 is dependent on glycosylation at Asn-102. Targeting to granules is not dependent on glycosylation, but unglycosylated rPR3 gets secreted preferentially into media supernatants. Finally, a capture ELISA for ANCA detection, using rPR3 glycosylation variants as target antigens, reveals that in about 20% of patients, epitope recognition by ANCA is affected by the glycosylation status of PR3.
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Affiliation(s)
- Ulrich Specks
- Thoracic Disease Research Unit, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
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Lee AS, Finkielman JD, Peikert T, Hummel AM, Viss MA, Specks U. A novel capture-ELISA for detection of anti-neutrophil cytoplasmic antibodies (ANCA) based on c-myc peptide recognition in carboxy-terminally tagged recombinant neutrophil serine proteases. J Immunol Methods 2005; 307:62-72. [PMID: 16242707 DOI: 10.1016/j.jim.2005.09.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Accepted: 09/06/2005] [Indexed: 11/26/2022]
Abstract
Testing for antineutrophil cytoplasmic antibodies (ANCA) reacting with proteinase 3 (PR3) is part of the routine diagnostic evaluation of patients with small vessel vasculitis. For PR3-ANCA detection, capture ELISAs are reported to be superior to direct ELISAs. Standard capture ELISAs, in which PR3 is anchored by anti-PR3 monoclonal antibodies (moAB), have two potential disadvantages. First, the capturing moAB may compete for epitopes recognized by some PR3-ANCA, causing occasional false-negative results. Second, the capture of recombinant PR3 mutant molecules becomes unpredictable as modifications of specific conformational epitopes may not only affect the binding of PR3-ANCA, but also the affinity of the capturing anti-PR3 moAB. Here, we describe a new capture ELISA, and its application for PR3-ANCA detection. This new assay is based on the standardized capture of a variety of different carboxy-terminally c-myc tagged recombinant ANCA target antigens using anti-c-myc coated ELISA plates. Antigen used include c-myc tagged human rPR3 variants (mature and pro-form conformations), mouse mature rPR3 and human recombinant neutrophil elastase. This new anti-c-myc-capture ELISA for PR3-ANCA detection has an intra- and inter-assay coefficient of variation of 3.6% to 7.7%, and 15.8% to 18.4%, respectively. The analytical sensitivity and specificity for PR3-ANCA positive serum samples were 93% and 100%, respectively when rPR3 with mature conformation was used as target antigen, and 83% and 100% when the pro-enzyme conformation was employed. In conclusion, this new anti-c-myc capture ELISA compares favorably to our standard capture ELISA for PR3-ANCA detection, enables the unified capture of different ANCA target antigens through binding to a c-myc tag, and allows capture of rPR3 mutants necessary for PR3-ANCA epitope mapping studies.
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Affiliation(s)
- Augustine S Lee
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic and Foundation, Rochester, MN 55905, USA
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Wiesner O, Litwiller RD, Hummel AM, Viss MA, McDonald CJ, Jenne DE, Fass DN, Specks U. Differences between human proteinase 3 and neutrophil elastase and their murine homologues are relevant for murine model experiments. FEBS Lett 2005; 579:5305-12. [PMID: 16182289 DOI: 10.1016/j.febslet.2005.08.056] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Revised: 08/11/2005] [Accepted: 08/31/2005] [Indexed: 11/16/2022]
Abstract
Direct comparisons of human (h) and murine (m) neutrophil elastase (NE) and proteinase 3 (PR3) are important for the understanding and interpretation of inflammatory and PR3-related autoimmune processes investigated in wild-type-, mNE- and mPR3/mNE knockout mice. To this end, we purified recombinant mPR3 and mNE expressed in HMC1 and 293 cells and compared their biophysical properties, proteolytic activities and susceptibility to inhibitors with those of their human homologues, hPR3 and hNE. Significant species differences in physico-chemical properties, substrate specificities and enzyme kinetics towards synthetic peptide substrates, oxidized insulin B chain, and fibrinogen were detected. MeOSuc-AAPV-pNA and Suc-AAPV-pNA were hydrolyzed more efficiently by mPR3 than hPR3, but enzymatic activities of mNE and hNE were very similar. Fibrinogen was cleaved much more efficiently by mPR3 than by hPR3. All four proteases were inhibited by alpha(1)-antitrypsin and elafin. Eglin C inihibited mNE, hNE, mPR3, but not hPR3. SLPI inhibited both NEs, but neither PR3. The custom-designed hNE inhibitor, Val(15)-aprotinin, is a poor inhibitor for mNE. In conclusion, appropriate interpretation of experiments in murine models requires individual species-specific assessment of neutrophil protease function and inhibition.
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Affiliation(s)
- Olaf Wiesner
- Thoracic Diseases Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic Foundation, Rochester, MN 55905, USA
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22
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Abstract
BACKGROUND Autoantibodies directed against neutrophil proteinase 3 (PR3-ANCA) from patients with Wegener's granulomatosis and microscopic polyangiitis recognize conformational epitopes of PR3. During maturation of neutrophils, PR3 undergoes amino-terminal and carboxy-terminal processing. In contrast to amino-terminal processing, the effects of carboxy-terminal processing on recognition of PR3 by PR3-ANCA remain unknown. Carboxy-terminally modified or tagged recombinant PR3 (rPR3) molecules may be useful for the refinement of diagnostic assays and for the study of biological processes. METHODS This study was designed to determine whether 293 cells can be used to express specifically designed carboxy-terminal variants of rPR3, and to evaluate the effects of different carboxy-terminal modifications on the recognition by PR3-ANCA in the capture ELISA. RESULTS The rPR3-variants secreted into the media supernatants of transfected 293 cells escaped proteolytic processing. Furthermore, in contrast to the effects of amino-terminal pro-peptide deletion on PR3-ANCA binding, carboxy-terminal modifications (deletion and additions) did not significantly affect recognition by PR3-ANCA. CONCLUSIONS This expression system is ideally suited for the expression of custom-designed carboxy-terminal rPR3 variants, and major conformational effects of carboxy-terminal modifications seem unlikely.
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Affiliation(s)
- Stephen A Capizzi
- Thoracic Diseases Research Unit and Hematology Research Unit, Mayo Graduate School of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA
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Sun J, Fass DN, Viss MA, Hummel AM, Tang H, Homburger HA, Specks U. A proportion of proteinase 3 (PR3)-specific anti-neutrophil cytoplasmic antibodies (ANCA) only react with PR3 after cleavage of its N-terminal activation dipeptide. Clin Exp Immunol 1998; 114:320-6. [PMID: 9822293 PMCID: PMC1905112 DOI: 10.1046/j.1365-2249.1998.00730.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ANCA directed against PR3 are highly specific for Wegener's granulomatosis and microscopic polyangiitis, and have been implicated in the pathogenesis of small vessel vasculitis. Most PR3-ANCA are directed against conformational epitopes on PR3. This study was designed to determine whether the cleavage of the N-terminal activation dipeptide of PR3 is required for the binding of PR3-ANCA. Recombinant PR3 (rPR3) variants were expressed in the epithelial cell line, 293. As confirmed by radiosequencing, the rPR3 secreted into the 293 cell culture supernatant is N-terminally unprocessed. Two enzymatically inactive rPR3 mutants were expressed in 293 cells: rPR3-S176A and delta-rPR3-S176A. rPR3-S176A contains the N-propetide Ala-2-Glu-1, delta-rPR3-S176A does not. Culture supernatants of rPR3-S176A and delta-rPR3-S176A expressing 293 cells were used as sources of target antigen for PR3-ANCA testing by capture ELISA. Forty unselected consecutive PR3-ANCA+ sera were tested. With delta-rPR3-S176A as antigen all 40 were recognized, compared with only 34 of 40 when rPR3-S176A served as target antigen. The majority of the serum samples contained a mixture of antibodies reacting with epitopes accessible on the mature and on the proform of PR3. In conclusion, the cleavage of the N-terminal activation dipeptide of PR3 is not an absolute requirement for recognition by all PR3-ANCA. However, a substantial proportion of PR3-ANCA recognize (a) target antigen(s) exposed only after the conformational change of PR3 associated with the N-terminal processing. In 15% of sera this PR3-ANCA subset occurred exclusively. PR3-ANCA subtypes can be differentiated using specifically designed rPR3 variants as target antigens, and non-haematopoietic mammalian cells without regulated secretory pathway can be used for their expression.
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Affiliation(s)
- J Sun
- Thoracic Diseases Research Unit, Mayo Clinic and Foundation, Rochester, MN 55905, USA
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Jenne DE, Fröhlich L, Hummel AM, Specks U. Cloning and functional expression of the murine homologue of proteinase 3: implications for the design of murine models of vasculitis. FEBS Lett 1997; 408:187-90. [PMID: 9187364 DOI: 10.1016/s0014-5793(97)00418-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Anti-neutrophil cytoplasmic autoantibodies recognizing conformational epitopes (c-ANCA) of proteinase 3 (PR3) from azurophil granules are a diagnostic hallmark in Wegener's granulomatosis (WG). Because a functional PR3 homologue has not been identified in rodents, it is difficult to assess immunopathological responses in rats or mice immunized with patients' derived c-ANCA or human PR3. Here we report the full length cDNA cloning and functional expression of murine PR3 in HMC-1 cells. Recombinant murine PR3 shows highly similar substrate specificities towards synthetic peptides and is inhibited by human alpha1-proteinase inhibitor like human PR3. However, neither human c-ANCA, rabbit sera nor mouse monoclonal antibodies to human PR3 recognize the murine homologue. Consequently, it is unlikely that disease observed in mice after immunization with c-ANCA or human PR3 is caused by pathogenic antibodies directed against mouse PR3. Recombinant human-mouse chimaeric variants will be a valuable new tool to localize the disease-specific immunodominant epitopes in human PR3.
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Affiliation(s)
- D E Jenne
- Max-Planck-Institut für Psychiatrie, Abt. Neuroimmunologie, Martinsried, Germany
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Specks U, Fass DN, Fautsch MP, Hummel AM, Viss MA. Recombinant human proteinase 3, the Wegener's autoantigen, expressed in HMC-1 cells is enzymatically active and recognized by c-ANCA. FEBS Lett 1996; 390:265-70. [PMID: 8706874 DOI: 10.1016/0014-5793(96)00669-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We developed a stable expression system for conformationally intact recombinant human PR3 (rPR3) using the human mast cell line HMC-1. Like in U937 cells, the rPR3 is processed from a 34 kDa precursor to the 29 kDa mature form, primarily as the result of oligosaccharide trimming. The rPR3 binds [3H]DFP and hydrolyzes the substrate N-methoxysuccinyl-Ala-Ala-Pro-Val-pNA. The enzymatic activity is inhibited by greater than 95% by alpha 1-PI. The rPR3 and the enzymatically inactive mutant rPR3-S176A are both packaged in granules. Thus, proteolytic autoprocessing is not required for PR3's targeting to granules. This rPR3 is the first to be recognized by most c-ANCA from WG patients and all anti-PR3 ANCA that were detected by standard anti-PR3 specific ELISA. This expression system for rPR3 represents a versatile tool for the analysis of its intracellular processing, structure-function relationships and interaction with autoantibodies.
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Affiliation(s)
- U Specks
- Thoracic Diseases Research Unit, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
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Williams CL, Hayes VY, Hummel AM, Tarara JE, Halsey TJ. Regulation of E-cadherin-mediated adhesion by muscarinic acetylcholine receptors in small cell lung carcinoma. J Biophys Biochem Cytol 1993; 121:643-54. [PMID: 8387530 PMCID: PMC2119556 DOI: 10.1083/jcb.121.3.643] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
We present the first evidence that adhesion mediated by a member of the cadherin gene family can be regulated by a G protein-coupled receptor. We show that activating the M3 muscarinic acetylcholine receptor (mAChR) rapidly induces E-cadherin-mediated adhesion in a small cell lung carcinoma (SCLC) cell line. This response is inhibited by E-cadherin antibodies, and does not occur in another SCLC cell line which expresses functional mAChR but reduced levels of E-cadherin. Protein kinase C may be involved, since phorbol 12-myristate 13-acetate also induces E-cadherin-mediated aggregation. Immunofluorescence analyses indicate that mAChR activation does not grossly alter E-cadherin surface expression or localization at areas of cell-cell contact, suggesting mAChR activation may increase E-cadherin binding activity. Our findings suggest that G protein-coupled receptors may regulate processes involving cadherin-mediated adhesion, such as embryonic development, neurogenesis, and cancer metastasis.
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Affiliation(s)
- C L Williams
- Department of Immunology, Mayo Clinic and Foundation, Rochester, Minnesota 55905
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