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Sharma P, Zonozi R, Geetha D. ANCA-Associated Vasculitis. ADVANCES IN KIDNEY DISEASE AND HEALTH 2024; 31:194-205. [PMID: 39004459 DOI: 10.1053/j.akdh.2024.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 04/19/2024] [Accepted: 04/24/2024] [Indexed: 07/16/2024]
Abstract
ANCA-associated vasculitis (AAV) is a necrotizing, small-to-medium vessel vasculitis associated with significant morbidity and mortality. AAV is a systemic autoimmune disease affecting kidneys, eyes, sinuses, peripheral nerves, skin, and upper and lower respiratory tracts. AAV tends to present in characteristic phenotypes categorized clinically as granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic GPA (EGPA). Kidney involvement is a common feature of AAV, and has important implications on disease prognosis and management. Existing therapies have been refined and improvements in our understanding of the pathophysiology of AAV has led to approval of novel therapies. In this review, we provide an overview of epidemiology, disease mechanisms, clinical presentation and review therapeutic strategies for induction and maintenance of remission.
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Affiliation(s)
- Purva Sharma
- Division of Kidney Disease and Hypertension, Northwell Health, The Glomerular Disease Center at Northwell Health.
| | - Reza Zonozi
- Nephrology Associates of Northern Virginia, Fairfax, VA; Inova Fairfax Hospital, Falls Church, VA
| | - Duvuru Geetha
- Division of Nephrology, Johns Hopkins University School of Medicine
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Poulton JS, Lamba S, Free M, Xi G, McInnis E, Williams G, Kudlacek ST, Thieker D, Kuhlman B, Falk R. High-resolution epitope mapping of commercial antibodies to ANCA antigens by yeast surface display. J Immunol Methods 2024; 528:113654. [PMID: 38432292 PMCID: PMC11023775 DOI: 10.1016/j.jim.2024.113654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/27/2024] [Accepted: 02/27/2024] [Indexed: 03/05/2024]
Abstract
Epitope mapping provides critical insight into antibody-antigen interactions. Epitope mapping of autoantibodies from patients with autoimmune diseases can help elucidate disease immunogenesis and guide the development of antigen-specific therapies. Similarly, epitope mapping of commercial antibodies targeting known autoantigens enables the use of those antibodies to test specific hypotheses. Anti-Neutrophil Cytoplasmic Autoantibody (ANCA) vasculitis results from the formation of autoantibodies to multiple autoantigens, including myeloperoxidase (MPO), proteinase-3 (PR3), plasminogen (PLG), and peroxidasin (PXDN). To perform high-resolution epitope mapping of commercial antibodies to these autoantigens, we developed a novel yeast surface display library based on a series of >5000 overlapping peptides derived from their protein sequences. Using both FACS and magnetic bead isolation of reactive yeast, we screened 19 commercially available antibodies to the ANCA autoantigens. This approach to epitope mapping resulted in highly specific, fine epitope mapping, down to single amino acid resolution in many cases. Our study also identified cross-reactivity between some commercial antibodies to MPO and PXDN, which suggests that patients with apparent autoantibodies to both proteins may be the result of cross-reactivity. Together, our data validate yeast surface display using maximally overlapping peptides as an excellent approach to linear epitope mapping.
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Affiliation(s)
- John S Poulton
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; UNC Kidney Center, Chapel Hill, North Carolina, USA.
| | - Sajan Lamba
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Meghan Free
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; UNC Kidney Center, Chapel Hill, North Carolina, USA
| | - Gang Xi
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; UNC Kidney Center, Chapel Hill, North Carolina, USA
| | - Elizabeth McInnis
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Gabrielle Williams
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Stephan T Kudlacek
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; Menten AI, San Francisco, California, USA
| | - David Thieker
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Brian Kuhlman
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Ronald Falk
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; UNC Kidney Center, Chapel Hill, North Carolina, USA
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Massicotte-Azarniouch D, Herrera CA, Jennette JC, Falk RJ, Free ME. Mechanisms of vascular damage in ANCA vasculitis. Semin Immunopathol 2022; 44:325-345. [PMID: 35254509 PMCID: PMC9064952 DOI: 10.1007/s00281-022-00920-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 02/02/2022] [Indexed: 12/12/2022]
Abstract
The discovery of anti-neutrophil cytoplasmic antibodies (ANCA) and their antigenic targets, myeloperoxidase (MPO) and proteinase 3 (PR3), has led to further understanding as to the pathophysiologic processes that underlie vascular and tissue damage in ANCA vasculitis. ANCA trigger neutrophil activation leading to vascular damage in ANCA vasculitis. However, decades of study have determined that neutrophil activation alone is not sufficient to cause disease. Inflammatory stimuli are drivers of ANCA autoantigen expression and ANCA production. Certain infections or bacterial peptides may be crucial players in the initial steps of ANCA immunopathogenesis. Genetic and epigenetic alterations of gene encoding for MPO and PR3 provide additional disturbances to the immune homeostasis which provide a substrate for pathogenic ANCA formation from an adaptive immune system predisposed to autoreactivity. Promoted by inflammatory cytokines, ANCA binding leads to neutrophil activation, a process characterized by conformational changes, production and release of cytotoxic substances, and alternative complement pathway activation, thus creating an intense inflammatory milieu. This cascade of events perpetuates a vicious cycle of further inflammatory cell recruitment and activation, culminating in tissue necrosis. Our understanding of the pathogenic process in ANCA vasculitis paves the way for the development of therapies targeting crucial steps in this process. The greater appreciation of the role for complement, monocytes, and the adaptive immune system has already led to novel complement blockers and is poised to lead to further innovations which will allow for tailored antigen- or cell-specific immunotherapy targeting the autoimmune process without exposure to undue risks or toxicities.
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Affiliation(s)
- David Massicotte-Azarniouch
- Division of Nephrology and Hypertension, Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Carolina A Herrera
- Division of Nephrology and Hypertension, Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - J Charles Jennette
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Ronald J Falk
- Division of Nephrology and Hypertension, Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Meghan E Free
- Division of Nephrology and Hypertension, Department of Medicine, University of North Carolina, Chapel Hill, NC, USA.
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Kargapolova Y, Geißen S, Zheng R, Baldus S, Winkels H, Adam M. The Enzymatic and Non-Enzymatic Function of Myeloperoxidase (MPO) in Inflammatory Communication. Antioxidants (Basel) 2021; 10:antiox10040562. [PMID: 33916434 PMCID: PMC8066882 DOI: 10.3390/antiox10040562] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/23/2021] [Accepted: 03/30/2021] [Indexed: 12/14/2022] Open
Abstract
Myeloperoxidase is a signature enzyme of polymorphonuclear neutrophils in mice and humans. Being a component of circulating white blood cells, myeloperoxidase plays multiple roles in various organs and tissues and facilitates their crosstalk. Here, we describe the current knowledge on the tissue- and lineage-specific expression of myeloperoxidase, its well-studied enzymatic activity and incoherently understood non-enzymatic role in various cell types and tissues. Further, we elaborate on Myeloperoxidase (MPO) in the complex context of cardiovascular disease, innate and autoimmune response, development and progression of cancer and neurodegenerative diseases.
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Free ME, Stember KG, Hess JJ, McInnis EA, Lardinois O, Hogan SL, Hu Y, Mendoza C, Le AK, Guseman AJ, Pilkinton MA, Bortone DS, Cowens K, Sidney J, Karosiene E, Peters B, James E, Kwok WW, Vincent BG, Mallal SA, Jennette JC, Ciavatta DJ, Falk RJ. Restricted myeloperoxidase epitopes drive the adaptive immune response in MPO-ANCA vasculitis. J Autoimmun 2020; 106:102306. [PMID: 31383567 PMCID: PMC6930338 DOI: 10.1016/j.jaut.2019.102306] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 07/16/2019] [Accepted: 07/17/2019] [Indexed: 12/11/2022]
Abstract
BACKGROUND Treatment of autoimmune diseases has relied on broad immunosuppression. Knowledge of specific interactions between human leukocyte antigen (HLA), the autoantigen, and effector immune cells, provides the foundation for antigen-specific therapies. These studies investigated the role of HLA, specific myeloperoxidase (MPO) epitopes, CD4+ T cells, and ANCA specificity in shaping the immune response in patients with anti-neutrophil cytoplasmic autoantibody (ANCA) vasculitis. METHODS HLA sequence-based typing identified enriched alleles in our patient population (HLA-DPB1*04:01 and HLA-DRB4*01:01), while in silico and in vitro binding studies confirmed binding between HLA and specific MPO epitopes. Class II tetramers with MPO peptides were utilized to detect autoreactive CD4+ T cells. TCR sequencing was performed to determine the clonality of T cell populations. Longitudinal peptide ELISAs assessed the temporal nature of anti-MPO447-461 antibodies. Solvent accessibility combined with chemical modification determined the buried regions of MPO. RESULTS We identified a restricted region of MPO that was recognized by both CD4+ T cells and ANCA. The autoreactive T cell population contained CD4+CD25intermediateCD45RO+ memory T cells and secreted IL-17A. T cell receptor (TCR) sequencing demonstrated that autoreactive CD4+ T cells had significantly less TCR diversity when compared to naïve and memory T cells, indicating clonal expansion. The anti-MPO447-461 autoantibody response was detectable at onset of disease in some patients and correlated with disease activity in others. This region of MPO that is targeted by both T cells and antibodies is not accessible to solvent or chemical modification, indicating these epitopes are buried. CONCLUSIONS These observations reveal interactions between restricted MPO epitopes and the adaptive immune system within ANCA vasculitis that may inform new antigen-specific therapies in autoimmune disease while providing insight into immunopathogenesis.
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Affiliation(s)
- Meghan E Free
- UNC Kidney Center, Department of Medicine, 7024 Burnett-Womack, CB #7155, Chapel Hill, NC, 27599, USA.
| | - Katherine G Stember
- UNC Kidney Center, Department of Medicine, 7024 Burnett-Womack, CB #7155, Chapel Hill, NC, 27599, USA; UNC Department of Pathology and Laboratory Medicine, CB #7525, Brinkhous-Bullitt Building, Chapel Hill, NC, 27599, USA
| | - Jacob J Hess
- UNC Kidney Center, Department of Medicine, 7024 Burnett-Womack, CB #7155, Chapel Hill, NC, 27599, USA
| | - Elizabeth A McInnis
- UNC Kidney Center, Department of Medicine, 7024 Burnett-Womack, CB #7155, Chapel Hill, NC, 27599, USA
| | - Olivier Lardinois
- UNC Kidney Center, Department of Medicine, 7024 Burnett-Womack, CB #7155, Chapel Hill, NC, 27599, USA
| | - Susan L Hogan
- UNC Kidney Center, Department of Medicine, 7024 Burnett-Womack, CB #7155, Chapel Hill, NC, 27599, USA
| | - Yichun Hu
- UNC Kidney Center, Department of Medicine, 7024 Burnett-Womack, CB #7155, Chapel Hill, NC, 27599, USA
| | - Carmen Mendoza
- UNC Kidney Center, Department of Medicine, 7024 Burnett-Womack, CB #7155, Chapel Hill, NC, 27599, USA
| | - Andrew K Le
- UNC Kidney Center, Department of Medicine, 7024 Burnett-Womack, CB #7155, Chapel Hill, NC, 27599, USA
| | - Alex J Guseman
- UNC Department of Chemistry, CB #3290, Chapel Hill, NC, 27599, USA
| | - Mark A Pilkinton
- Vanderbilt Center for Translational Immunology and Infectious Diseases, A2200 MCN, 1161 21st Avenue South, Nashville, TN, 37232, USA
| | - Dante S Bortone
- UNC Lineberger Comprehensive Cancer Center, CB #7295, Chapel Hill, NC, 27599, USA
| | - Kristen Cowens
- UNC Lineberger Comprehensive Cancer Center, CB #7295, Chapel Hill, NC, 27599, USA
| | - John Sidney
- La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA, 92037, USA
| | - Edita Karosiene
- La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA, 92037, USA
| | - Bjoern Peters
- La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA, 92037, USA
| | - Eddie James
- Benaroya Research Institute, 1201 Ninth Avenue, Seattle, WA, 98101, USA
| | - William W Kwok
- Benaroya Research Institute, 1201 Ninth Avenue, Seattle, WA, 98101, USA
| | - Benjamin G Vincent
- UNC Lineberger Comprehensive Cancer Center, CB #7295, Chapel Hill, NC, 27599, USA; UNC Division of Hematology/Oncology, Department of Medicine, Physician's Office Building, 3rd Floor, 170 Manning Drive, CB #7305, Chapel Hill, NC, 27599, USA; UNC Curriculum in Bioinformatics and Computational Biology, CB #7264, Chapel Hill, NC, 27599, USA
| | - Simon A Mallal
- Vanderbilt Center for Translational Immunology and Infectious Diseases, A2200 MCN, 1161 21st Avenue South, Nashville, TN, 37232, USA
| | - J Charles Jennette
- UNC Kidney Center, Department of Medicine, 7024 Burnett-Womack, CB #7155, Chapel Hill, NC, 27599, USA; UNC Department of Pathology and Laboratory Medicine, CB #7525, Brinkhous-Bullitt Building, Chapel Hill, NC, 27599, USA
| | - Dominic J Ciavatta
- UNC Kidney Center, Department of Medicine, 7024 Burnett-Womack, CB #7155, Chapel Hill, NC, 27599, USA; UNC Department of Genetics and Molecular Biology, Coker Hall, 120 South Road, CB #3280, Chapel Hill, NC, 27599, USA
| | - Ronald J Falk
- UNC Kidney Center, Department of Medicine, 7024 Burnett-Womack, CB #7155, Chapel Hill, NC, 27599, USA; UNC Department of Pathology and Laboratory Medicine, CB #7525, Brinkhous-Bullitt Building, Chapel Hill, NC, 27599, USA
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Affiliation(s)
- Jason C George
- Department of Nephrology, Geisinger Medical Center, Danville, Pennsylvania, USA
| | - Prince Mohan
- Department of Nephrology, Geisinger Medical Center, Danville, Pennsylvania, USA
| | - Kevin Ho
- Department of Nephrology, Geisinger Medical Center, Danville, Pennsylvania, USA
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Yu JT, Li JN, Wang J, Jia XY, Cui Z, Zhao MH. Deglycosylation of myeloperoxidase uncovers its novel antigenicity. Kidney Int 2017; 91:1410-1419. [PMID: 28187981 DOI: 10.1016/j.kint.2016.12.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 11/14/2016] [Accepted: 12/01/2016] [Indexed: 02/03/2023]
Abstract
Myeloperoxidase (MPO) is a common target antigen of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis and is recognized in one-third of patients with anti-glomerular basement membrane (GBM) disease. Our previous study identified over 60% of patients with anti-GBM disease recognizing linear peptides of MPO heavy chain. Here we tested whether aberrant glycosylation alters MPO antigenicity through exposure of neo-epitopes on MPO molecules. Atypical glycosylated MPO molecules, including all possible glycosylation types, were prepared by exoglycosidase and endoglycosidase treatments. Antibodies were detected from the sera of 40 patients with anti-GBM disease without the coexistence of MPO-ANCA. Circulating antibodies against aberrant glycosylated MPO existed in 21 of these patients. Non-glycan MPO and MPO with only N-acetylglucosamine had high frequencies of recognition (16 and 15 patients, respectively). Antibodies binding to aberrant glycosylated MPO could not be inhibited by intact MPO or GBM antigen. When applied to ethanol-fixed neutrophils from normal individuals, these antibodies yielded a typical cytoplasmic staining pattern (c-ANCA). Antigen specificity was detected in 90% of the antibodies using five peptides containing one of the five N-glycosylation sites each, mostly on N323, N355, and N391. The antibodies were restricted to IgG1 subclass, could activate complement, and induce neutrophil degranulation in vitro. Thus, aberrant glycosylated MPO exposed neo-epitopes and was recognized by half of the patients with anti-GBM disease. Their antibodies possessed pathogenic characteristics and may be associated with kidney injury.
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Affiliation(s)
- Jun-Tao Yu
- Renal Division, Peking University First Hospital, Institute of Nephrology, Peking University, Beijing, China; Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China; Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education of China, Beijing, China; Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China; Peking-Tsinghua Center for Life Sciences, Beijing, China
| | - Jian-Nan Li
- Renal Division, Peking University First Hospital, Institute of Nephrology, Peking University, Beijing, China; Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China; Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education of China, Beijing, China
| | - Jia Wang
- Renal Division, Peking University First Hospital, Institute of Nephrology, Peking University, Beijing, China; Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China; Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education of China, Beijing, China
| | - Xiao-Yu Jia
- Renal Division, Peking University First Hospital, Institute of Nephrology, Peking University, Beijing, China; Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China; Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education of China, Beijing, China
| | - Zhao Cui
- Renal Division, Peking University First Hospital, Institute of Nephrology, Peking University, Beijing, China; Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China; Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education of China, Beijing, China.
| | - Ming-Hui Zhao
- Renal Division, Peking University First Hospital, Institute of Nephrology, Peking University, Beijing, China; Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China; Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education of China, Beijing, China; Peking-Tsinghua Center for Life Sciences, Beijing, China
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Land J, Rutgers A, Kallenberg CGM. Anti-neutrophil cytoplasmic autoantibody pathogenicity revisited: pathogenic versus non-pathogenic anti-neutrophil cytoplasmic autoantibody. Nephrol Dial Transplant 2014; 29:739-45. [PMID: 24398891 DOI: 10.1093/ndt/gft416] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) is strongly associated with autoantibodies against myeloperoxidase (MPO) and proteinase 3 (PR3). No clear consensus has been reached on the pathogenicity of these autoantibodies. Animal models for MPO-ANCA, in vitro data suggesting pathogenicity of ANCA, and one case of a neonate showing symptoms of vasculitis after transplacental transfer of MPO, argue in favour of a pathogenic role for ANCA. On the other hand, the presence of natural MPO and PR3 autoantibodies in healthy individuals, lack of a strong correlation between ANCA titres and disease activity, and the occurrence of ANCA-negative AAV patients argue against pathogenicity of ANCA. Recent papers have drawn attention to the possibility of epitope specificity defining ANCA pathogenicity. Certain MPO epitopes were found to be specific for active disease, and others remained present during remission or were also present in healthy individuals. One linear epitope, aa447-459, was not only exclusive for active disease, but also detected in the total Ig fraction of ANCA-negative patients, reactivity being masked in serum by ceruloplasmin. So, not all ANCA seems to be equal, some could be pathogenic while others are not. For development of an autoimmune response, a specific ANCA repertoire is required, which may occur through intra-molecular epitope spreading in patients.
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Affiliation(s)
- Judith Land
- Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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Gou SJ, Xu PC, Chen M, Zhao MH. Epitope analysis of anti-myeloperoxidase antibodies in patients with ANCA-associated vasculitis. PLoS One 2013; 8:e60530. [PMID: 23577119 PMCID: PMC3618278 DOI: 10.1371/journal.pone.0060530] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 02/27/2013] [Indexed: 12/11/2022] Open
Abstract
Objective Increasing evidences have suggested the pathogenic role of anti-neutrophil cytoplasmic antibodies (ANCA) directing myeloperoxidase (MPO) in ANCA-associated vasculitis (AAV). The current study aimed to analyze the association between the linear epitopes of MPO-ANCA and clinicopathological features of patients with AAV. Methods Six recombinant linear fragments, covering the whole length amino acid sequence of a single chain of MPO, were produced from E.coli. Sera from 77 patients with AAV were collected at presentation. 13 out of the 77 patients had co-existence of serum anti-GBM antibodies. Ten patients also had sequential sera during follow up. The epitope specificities were detected by enzyme-linked immunosorbent assay using the recombinant fragments as solid phase ligands. Results Sera from 45 of the 77 (58.4%) patients with AAV showed a positive reaction to one or more linear fragments of the MPO chain. The Birmingham Vasculitis Activity Scores and the sera creatinine were significantly higher in patients with positive binding to the light chain fragment than that in patients without the binding. The epitopes recognized by MPO-ANCA from patients with co-existence of serum anti-GBM antibodies were mainly located in the N-terminus of the heavy chain. In 5 out of the 6 patients, whose sera in relapse recognize linear fragments, the reactivity to linear fragments in relapse was similar to that of initial onset. Conclusion The epitope specificities of MPO-ANCA were associated with disease activity and some clinicopathological features in patients with ANCA-associated vasculitis.
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Affiliation(s)
- Shen-Ju Gou
- Renal Division, Department of Medicine, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
| | - Peng-Cheng Xu
- Renal Division, Department of Medicine, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
| | - Min Chen
- Renal Division, Department of Medicine, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
- * E-mail:
| | - Ming-Hui Zhao
- Renal Division, Department of Medicine, Peking University First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Beijing, China
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Roth AJ, Ooi JD, Hess JJ, van Timmeren MM, Berg EA, Poulton CE, McGregor J, Burkart M, Hogan SL, Hu Y, Winnik W, Nachman PH, Stegeman CA, Niles J, Heeringa P, Kitching AR, Holdsworth S, Jennette JC, Preston GA, Falk RJ. Epitope specificity determines pathogenicity and detectability in ANCA-associated vasculitis. J Clin Invest 2013; 123:1773-83. [PMID: 23549081 DOI: 10.1172/jci65292] [Citation(s) in RCA: 160] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 01/22/2013] [Indexed: 11/17/2022] Open
Abstract
Anti-neutrophil cytoplasmic antibody-associated (ANCA-associated) small vessel necrotizing vasculitis is caused by immune-mediated inflammation of the vessel wall and is diagnosed in some cases by the presence of myeloperoxidase-specific antibodies (MPO-ANCA). This multicenter study sought to determine whether differences in ANCA epitope specificity explain why, in some cases, conventional serologic assays do not correlate with disease activity, why naturally occurring anti-MPO autoantibodies can exist in disease-free individuals, and why ANCA are undetected in patients with ANCA-negative disease. Autoantibodies from human and murine samples were epitope mapped using a highly sensitive epitope excision/mass spectrometry approach. Data indicated that MPO autoantibodies from healthy individuals had epitope specificities different from those present in ANCA disease. Importantly, this methodology led to the discovery of MPO-ANCA in ANCA-negative disease that reacted against a sole linear sequence. Autoantibodies against this epitope had pathogenic properties, as demonstrated by their capacity to activate neutrophils in vitro and to induce nephritis in mice. The confounder for serological detection of these autoantibodies was the presence of a fragment of ceruloplasmin in serum, which was eliminated in purified IgG, allowing detection. These findings implicate immunodominant epitopes in the pathology of ANCA-associated vasculitis and suggest that autoantibody diversity may be common to other autoimmune diseases.
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Affiliation(s)
- Aleeza J Roth
- UNC Kidney Center, Department of Medicine, Division of Nephrology and Hypertension, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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Radice A, Bianchi L, Maggiore U, Vaglio A, Sinico RA. Comparison of PR3-ANCA specific assay performance for the diagnosis of granulomatosis with polyangiitis (Wegener’s). Clin Chem Lab Med 2013; 51:2141-9. [DOI: 10.1515/cclm-2013-0308] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 05/27/2013] [Indexed: 11/15/2022]
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Pires KMP, Melo AC, Lanzetti M, Casquilho NV, Zin WA, Porto LC, Valença SS. Low tidal volume mechanical ventilation and oxidative stress in healthy mouse lungs. J Bras Pneumol 2012; 38:98-104. [PMID: 22407046 DOI: 10.1590/s1806-37132012000100014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 12/01/2011] [Indexed: 01/19/2023] Open
Abstract
OBJECTIVE Mechanical ventilation (MV) itself can directly contribute to lung injury. Therefore, the aim of the present study was to investigate early biomarkers concerning oxidant/antioxidant balance, oxidative stress, and inflammation caused by short-term MV in healthy mouse lungs. METHODS Twenty male C57BL/6 mice were randomly divided into two groups: MV, submitted to low tidal volume (V T, 6 mL/kg) MV for 30 min; and spontaneous respiration (SR), used as controls. Lung homogenate samples were tested regarding the activity of various antioxidant enzymes, lipid peroxidation, and TNF-α expression. RESULTS In comparison with the SR group, the MV group showed a significant decrease in the activity of superoxide dismutase (≈35%; p < 0.05), together with an increase in the activity of catalase (40%; p < 0.01), glutathione peroxidase (500%; p < 0.001), and myeloperoxidase (260%; p < 0.001), as well as a reduction in the glutathione/oxidized glutathione ratio (≈50%; p < 0.05) and an increase in TNF-α expression in the MV group. Oxidative damage, assessed by lipid peroxidation, was also greater in the MV group (45%; p < 0.05). CONCLUSIONS Our results show that short-term low V T MV can directly contribute to lung injury, generating oxidative stress and inflammation in healthy mouse lungs.
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Affiliation(s)
- Karla Maria Pereira Pires
- Departamento de Histologia e Embriologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
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The immunodominant myeloperoxidase T-cell epitope induces local cell-mediated injury in antimyeloperoxidase glomerulonephritis. Proc Natl Acad Sci U S A 2012; 109:E2615-24. [PMID: 22955884 DOI: 10.1073/pnas.1210147109] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Microscopic polyangiitis is an autoimmune small-vessel vasculitis that often manifests as focal and necrotizing glomerulonephritis and renal failure. Antineutrophil cytoplasmic Abs (ANCAs) specific for myeloperoxidase (MPO) play a role in this disease, but the role of autoreactive MPO-specific CD4(+) T cells is uncertain. By screening overlapping peptides of 20 amino acids spanning the MPO molecule, we identified an immunodominant MPO CD4(+) T-cell epitope (MPO(409-428)). Immunizing C57BL/6 mice with MPO(409-428) induced focal necrotizing glomerulonephritis similar to that seen after whole MPO immunization, when MPO was deposited in glomeruli. Transfer of an MPO(409-428)-specific CD4(+) T-cell clone to Rag1(-/-) mice induced focal necrotizing glomerulonephritis when glomerular MPO deposition was induced either by passive transfer of MPO-ANCA and LPS or by planting MPO(409-428) conjugated to a murine antiglomerular basement membrane mAb. MPO(409-428) also induced biologically active anti-MPO Abs in mice. The MPO(409-428) epitope has a minimum immunogenic core region of 11 amino acids, MPO(415-426), with several critical residues. ANCA-activated neutrophils not only induce injury but lodged the autoantigen MPO in glomeruli, allowing autoreactive anti-MPO CD4(+) cells to induce delayed type hypersensitivity-like necrotizing glomerular lesions. These studies identify an immunodominant MPO T-cell epitope and redefine how effector responses can induce injury in MPO-ANCA-associated microscopic polyangiitis.
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Radice A, Bianchi L, Sinico RA. Anti-neutrophil cytoplasmic autoantibodies: methodological aspects and clinical significance in systemic vasculitis. Autoimmun Rev 2012; 12:487-95. [PMID: 22921790 DOI: 10.1016/j.autrev.2012.08.008] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Antineutrophil cytoplasmic antibodies (ANCA) are the serological hallmark of some idiopathic systemic vasculitides, such as granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and, to a lesser extent, Churg-Strauss syndrome (CCS), the so-called ANCA-associated vasculitides (AAV). ANCA were first detected by immunofluorescence (IIFT), subsequently the target antigens myeloperoxidase (MPO) and proteinase 3 (PR3) were identified, allowing the development of the quantitative, antigen-specific assays. According to the guidelines, combining IIFT and PR3-ANCA/MPO-ANCA assures the optimal diagnostic specificity. Antigen specificity does not effectively differentiate among the different AAV, however C-ANCA/PR3-ANCA are mainly found in GPA, while P-ANCA/MPO-ANCA are more prevalent in MPA and CSS. Despite their diagnostic value, the performance of the widespread immunometric assays for ANCA testing is disappointing, particularly for the low sensitivity. In recent years, more "sensitive" assays have been developed, using the microplate as well as fully the automated technologies, with promising preliminary results. ANCA, may be detected in a number of pathological conditions other than small vessel vasculitis. However, in most of these non-vasculitic patients ANCA do not recognize MPO or PR3 as target antigens, but other granulocyte components, often multiple or unknown specificities. A positive ANCA result by itself is not diagnostic for AAV, clinical evidence and possibly histological confirmation are always required. On the other hand, a negative test result cannot completely rule out a diagnosis of AAV, as AAV without detectable ANCA exist. The appropriate use of ANCA testing strongly improves the diagnostic accuracy and clinical usefulness of the results.
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Affiliation(s)
- Antonella Radice
- Microbiology Institute, San Carlo Borromeo Hospital, Milan, Italy.
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Cheng G, Li H, Cao Z, Qiu X, McCormick S, Thannickal VJ, Nauseef WM. Vascular peroxidase-1 is rapidly secreted, circulates in plasma, and supports dityrosine cross-linking reactions. Free Radic Biol Med 2011; 51:1445-53. [PMID: 21798344 PMCID: PMC3439998 DOI: 10.1016/j.freeradbiomed.2011.07.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 06/10/2011] [Accepted: 07/04/2011] [Indexed: 02/07/2023]
Abstract
Members of the peroxidase-cyclooxygenase superfamily catalyze biochemical reactions essential to a broad spectrum of biological processes, including host defense, thyroid hormone biosynthesis, and modification of extracellular matrix, as well as contributing to the pathogenesis of chronic inflammatory diseases. We recently identified a novel member of this family, vascular peroxidase-1 (VPO1), that is highly expressed in the human cardiovascular system. Its biosynthesis and enzymatic properties are largely unknown. Here, we report that VPO1 was rapidly and efficiently secreted into the extracellular space when the gene was stably expressed in human embryonic kidney (HEK) cells. Secreted VPO1 is a monomer with complex N-linked oligosaccharides and exhibits peroxidase activity. Biosynthesis of endogenous VPO1 by cultured human umbilical vein endothelial cells (HUVECs) shares features exhibited by heterologous expression of recombinant VPO1 (rVPO1) in HEK cells. The proinflammatory agents lipopolysaccharide and tumor necrosis factor-α induce expression of VPO1 mRNA and protein in HUVECs. Furthermore, murine and bovine sera and human plasma contain enzymatically active VPO1. rVPO1 exhibits spectral and enzymatic properties characteristic of the peroxidase-cyclooxygenase family, except with regard to its heat stability. rVPO1 catalyzes tyrosyl radical formation and promotes dityrosine cross-linking. Taken together, these data demonstrate that VPO1 is a glycosylated heme peroxidase that is actively secreted into circulating plasma by vascular endothelial cells and shares several features with other members of the peroxidase-cyclooxygenase family, including the catalysis of dityrosine formation.
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Affiliation(s)
- Guangjie Cheng
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama School of Medicine, Birmingham, AL, USA
- Correspondence: Guangjie Cheng, Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama School of Medicine, BMR2, Room 410, 1530 3rd Avenue South, Birmingham, AL, 35294 USA; Phone 205-975-8919; Fax 205-975-3043, ; or William M. Nauseef, Inflammation Program, Department of Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa and Veterans Affairs Medical Center, Coralville, Iowa City, IA, USA; Phone 319-335-4278; Fax 319-335-4194;
| | - Hong Li
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama School of Medicine, Birmingham, AL, USA
| | - Zehong Cao
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama School of Medicine, Birmingham, AL, USA
| | - Xiaoyun Qiu
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama School of Medicine, Birmingham, AL, USA
| | - Sally McCormick
- Inflammation Program, Department of Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa and Veterans Affairs Medical Center, Coralville, Iowa City, IA, USA
| | - Victor J. Thannickal
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama School of Medicine, Birmingham, AL, USA
| | - William M. Nauseef
- Inflammation Program, Department of Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa and Veterans Affairs Medical Center, Coralville, Iowa City, IA, USA
- Correspondence: Guangjie Cheng, Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Alabama School of Medicine, BMR2, Room 410, 1530 3rd Avenue South, Birmingham, AL, 35294 USA; Phone 205-975-8919; Fax 205-975-3043, ; or William M. Nauseef, Inflammation Program, Department of Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa and Veterans Affairs Medical Center, Coralville, Iowa City, IA, USA; Phone 319-335-4278; Fax 319-335-4194;
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Xu PC, Chen M, Zhao MH. High potential to reverse the inhibition of myeloperoxidase by ceruloplasmin of anti-myeloperoxidase autoantibodies of IgG3 subclass. Autoimmunity 2011; 45:218-25. [DOI: 10.3109/08916934.2011.596867] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Bruner BF, Vista ES, Wynn DM, James JA. Epitope specificity of myeloperoxidase antibodies: identification of candidate human immunodominant epitopes. Clin Exp Immunol 2011; 164:330-6. [PMID: 21401576 DOI: 10.1111/j.1365-2249.2011.04372.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Anti-neutrophil cytoplasmic autoantibodies (ANCA) are a common feature of systemic vasculitides and have been classified as autoimmune conditions based, in part, on these autoantibodies. ANCA are subdivided further based on their primary target: cytoplasm (c-ANCA) or perinuclear region (p-ANCA). p-ANCAs commonly target myeloperoxidase (MPO), an enzyme with microbicidal and degradative activity. MPO antibodies are non-specific for any single disease and found in a variety of vasculitides, most commonly microscopic polyangiitis. Despite their prevalence, their role in human disease pathogenesis remains undefined. We sought to characterize the sequential antigenic determinants of MPO in vasculitis patients with p-ANCA. Of 68 patients with significant levels of p-ANCA, 12 have significant levels of MPO antibodies and were selected for fine specificity epitope mapping. Sequential antigenic targets, including those containing amino acids (aa) 213-222 (WTPGVKRNGF) and aa 511-522 (RLDNRYQPMEPN), were commonly targeted with a prevalence ranging from 33% to 58%. Subsequent analysis of autoantibody binding to the RLDNRYQPMEPN peptide was assessed using a confirmatory enzyme-linked immunosorbent assay format, with six patients displaying significant binding using this method. Antibodies against this epitope, along with four others (aa 393-402, aa 437-446, aa 479-488 and aa 717-726), were reactive to the heavy chain structure of the MPO protein. One epitope, GSASPMELLS (aa 91-100), was within the pro-peptide structure of MPO. B cell epitope prediction algorithms identified all or part of the seven epitopes defined. These results provide major common human anti-MPO immunodominant antigenic targets which can be used to examine further the potential pathogenic mechanisms for these autoantibodies.
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Affiliation(s)
- B F Bruner
- Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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Xu PC, Cui Z, Chen M, Hellmark T, Zhao MH. Comparison of characteristics of natural autoantibodies against myeloperoxidase and anti-myeloperoxidase autoantibodies from patients with microscopic polyangiitis. Rheumatology (Oxford) 2011; 50:1236-43. [PMID: 21372002 DOI: 10.1093/rheumatology/ker085] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE Natural autoantibodies (NAAs) against MPO exist in normal human plasma. In the current study, the immune characteristics of MPO-NAA and MPO-ANCA were examined and compared with the aim to investigate the pathogenesis of MPO-ANCA. METHODS MPO-NAAs were affinity purified from normal plasma of five healthy blood donors and one batch of IVIG. MPO-ANCAs were purified from plasma of 10 patients with MPA. Antigen specificity of the antibodies was tested by western blot analysis. The titre, the avidity, the Immunoglobulin G (IgG) subclasses and the effect of the antibodies towards the binding between ceruloplasmin and MPO were tested using ELISAs. The MPO-NAA-induced production of reactive oxygen species was assessed using oxidation of dihydrorhodamine (DHR) to rhodamine. RESULTS MPO-NAA recognized epitope(s) in the heavy chains of MPO with conformation-dependent structure, the same as MPO-ANCA. The median titre of MPO-NAA was lower than that of MPO-ANCA (1 : 40 vs 1 : 4800, P < 0.001). The median avidity of MPO-NAA was lower than that of MPO-ANCA (2.2 × 10(7) vs 8.7 × 10(7)/M, P = 0.014). The IgG subclasses of MPO-NAA were mainly restricted to IgG1 (100%) and lack of IgG3. The inhibition effect on the binding between ceruloplasmin and MPO was lower for MPO-NAA than MPO-ANCA (P = 0.046). The MPO-NAA-induced respiratory burst of neutrophils was significantly weaker than that of MPO-ANCA (P = 0.036). CONCLUSION The lower titre, lower avidity and lack of IgG3 subclass compared with MPO-ANCA may contribute to the non-pathogenic co-existence of MPO-NAA with MPO in serum.
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Affiliation(s)
- Peng-Cheng Xu
- Department of Medicine, Renal Division, Peking University First Hospital, Institute of Nephrology, Peking University, Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China
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Ravnsborg T, Houen G, Højrup P. The glycosylation of myeloperoxidase. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1804:2046-53. [DOI: 10.1016/j.bbapap.2010.07.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 06/29/2010] [Accepted: 07/01/2010] [Indexed: 10/19/2022]
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Xu PC, Chen M, Cui Z, Zhao MH. Influence of myeloperoxidase by anti-myeloperoxidase antibodies and its association with the disease activity in microscopic polyangiitis. Rheumatology (Oxford) 2010; 49:2068-75. [DOI: 10.1093/rheumatology/keq203] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Reduction of MPO-ANCA epitopes in SCG/Kj mice by 15-deoxyspergualin treatment restricted by IgG2b associated with crescentic glomerulonephritis. Rheumatology (Oxford) 2010; 49:1245-56. [DOI: 10.1093/rheumatology/keq087] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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Abstract
Proteinase 3 (PR3)-anti-neutrophil cytoplasmic antibodies (ANCA) and myeloperoxidase (MPO)-ANCA are suggested to play a pathogenic role as they are closely related to the small-vessel vasculitis syndromes, Wegener's granulomatosis and microscopic polyangiitis. A large body of in vitro and animal experiments supports this concept. The mechanisms of action involve a direct interaction between ANCA and its antigen. The epitope specificity of ANCA may therefore influence the functional effects of ANCA and/or may reflect the mechanisms behind different disease manifestations or disease courses.
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Affiliation(s)
- Ulrich Specks
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
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Pressler BM, Robarge ME, Anderson KI. Partial characterization of feline myeloperoxidase and investigation of its potential role as an autoantigen in hyperthyroid cats. Am J Vet Res 2009; 70:869-78. [PMID: 19566472 DOI: 10.2460/ajvr.70.7.869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To partially characterize the cDNA, amino acid sequence, and tertiary structure of feline myeloperoxidase, describe its cellular location in mature granulocytes, and determine whether hyperthyroid cats have anti-myeloperoxidase antibody. SAMPLE POPULATION Bone marrow RNA and whole blood from cats of various sources and feline serum samples submitted for measurement of total thyroxine concentration from September 2006 to July 2007. PROCEDURES Feline myeloperoxidase cDNA was amplified from bone marrow RNA; presumptive splice sites were determined by comparison with human sequences. Intracellular localization of myeloperoxidase in granulocytes was determined by use of immunofluorescence and electron microscopy, and molecular weight and partial tertiary structure were determined by use of immunoblotting of granulocyte lysates. Anti-human myeloperoxidase (hMPO) antibody was detected via ELISA. RESULTS A 2,493-bp sequence encompassing the 2,160-bp cDNA with presumably the same number and size of exons as hMPO was generated. Translation predicted 85% homology with hMPO. Feline myeloperoxidase was localized to neutrophil primary granules, and immunoblotting revealed heavy and light bands with molecular weights similar to those of hMPO. The prevalence of anti-hMPO antibody did not differ between nonhyperthyroid and hyperthyroid cats or among hyperthyroid cats subclassified by treatment modality. CONCLUSIONS AND CLINICAL RELEVANCE Moderate homology existed between feline myeloperoxidase and hMPO cDNA and protein. Although findings suggested a similar tertiary structure and function for the 2 proteins, they also suggested that inability to detect a high prevalence of anti-hMPO antibody in hyperthyroid cats may be attributable to antigenic differences between the human and feline proteins rather than a lack of autoantibody.
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Affiliation(s)
- Barrak M Pressler
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA
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Danila MI, Bridges SL. Update on pathogenic mechanisms of systemic necrotizing vasculitis. Curr Rheumatol Rep 2009; 10:430-5. [PMID: 19007531 DOI: 10.1007/s11926-008-0070-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Systemic necrotizing vasculitis is rare but can have serious sequelae. Despite recent advances in cellular and molecular immunology and genetics, the causes of vasculitic syndromes remain largely undefined. Although mechanisms of blood vessel damage in systemic necrotizing vasculitis are complex, recent studies have provided significant insights.
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Affiliation(s)
- Maria I Danila
- Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, 1530 3rd Avenue South, 805 FOT, Birmingham, AL 35294, USA.
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LIU LIJUN, CHEN MIN, YU FENG, ZHAO MINGHUI, WANG HAIYAN. IgG subclass distribution, affinity of anti-myeloperoxidase antibodies in sera from patients with Wegener's granulomatosis and microscopic polyangiitis. Nephrology (Carlton) 2008; 13:629-35. [DOI: 10.1111/j.1440-1797.2008.00976.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bunch DO, Silver JS, Majure MC, Sullivan P, Alcorta DA, Chin H, Hogan SL, Lindstrom YI, Clarke SH, Falk RJ, Nachman PH. Maintenance of tolerance by regulation of anti-myeloperoxidase B cells. J Am Soc Nephrol 2008; 19:1763-73. [PMID: 18650487 DOI: 10.1681/asn.2007030382] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Anti-neutrophil cytoplasmic autoantibodies directed toward myeloperoxidase or proteinase 3 are detected in sera of patients with small vessel vasculitis and participate in the pathogenesis of this disease. Autoantibodies develop when self-reactive B cells escape the regulation that ensures self-tolerance. In this study, regulation of anti-myeloperoxidase B cells was examined in mice that express an anti-myeloperoxidase Vkappa1C-Jkappa5 light-chain transgene, which confers anti-myeloperoxidase specificity when combined with a variety of heavy chains. Vkappa1C-Jkappa5 transgenic mice have splenic anti-myeloperoxidase B cells but do not produce circulating anti-myeloperoxidase antibodies. Two groups of transgenic mice that differed by their relative dosage of the transgene were compared; high-copy mice had a mean relative transgene dosage of 1.92 compared with 1.02 in the low-copy mice. These mice exhibited a 90 and 60% decrease in mature follicular B cells, respectively. High-copy mice were characterized by a large population of anti-myeloperoxidase B cells, a preponderance of B-1 cells, and an increased percentage of apoptotic myeloperoxidase-binding B cells. Low-copy mice had similar changes in B cell phenotype with the exception of an expanded marginal zone population. B cells from low-copy mice but not high-copy mice produced anti-myeloperoxidase antibodies after stimulation with lipopolysaccharide. These results indicate that tolerance to myeloperoxidase is maintained by central and peripheral deletion and that some myeloperoxidase-binding B cells are positively selected into the marginal zone and B-1 B cell subsets. A defect in these regulatory pathways could result in autoimmune disease.
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Affiliation(s)
- Donna O Bunch
- UNC Kidney Center, Department of Medicine, Division of Nephrology and Hypertension, University of North Carolina, 5005 Burnett-Womack, Campus Box #7155, Chapel Hill, NC 27599, USA.
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Goedken M, McCormick S, Leidal KG, Suzuki K, Kameoka Y, Astern JM, Huang M, Cherkasov A, Nauseef WM. Impact of Two Novel Mutations on the Structure and Function of Human Myeloperoxidase. J Biol Chem 2007; 282:27994-8003. [PMID: 17650507 DOI: 10.1074/jbc.m701984200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The heme protein myeloperoxidase (MPO) contributes critically to O(2)-dependent neutrophil antimicrobial activity. Two Japanese adults were identified with inherited MPO deficiency because of mutations at Arg-499 or Gly-501, conserved residues near the proximal histidine in the heme pocket. Because of the proximity of these residues to a critical histidine in the heme pocket, we examined the biosynthesis, function, and spectral properties of the peroxidase stably expressed in human embryonic kidney cells. Biosynthesis of normal MPO by human embryonic kidney cells faithfully mirrored events previously identified in cells expressing endogenous MPO. Mutant apopro-MPO was 90 kDa and interacted normally with the molecular chaperones ERp57, calreticulin, and calnexin in the endoplasmic reticulum. However, mutant precursors were not proteolytically processed into subunits of MPO, although secretion of the unprocessed precursors occurred normally. Although delta-[(14)C]aminolevulinic acid incorporation demonstrated formation of pro-MPO in both mutants, neither protein was enzymatically active. The Soret band for each mutant was shifted from the normal 430 to approximately 412 nm, confirming that heme was incorporated but suggesting that the number of covalent bonds or other structural aspects of the heme pocket were disrupted by the mutations. These studies demonstrate that despite heme incorporation, mutations in the heme environs compromised the oxidizing potential of MPO.
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Affiliation(s)
- Melissa Goedken
- Inflammation Program, Department of Medicine, University of Iowa and Veterans Affairs Medical Center, Iowa City, Iowa 52241, USA
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Bibliography. Current world literature. Vasculitis syndromes. Curr Opin Rheumatol 2006; 19:81-5. [PMID: 17143101 DOI: 10.1097/bor.0b013e32801437a8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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