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Chung EYM, Wang YM, Keung K, Hu M, McCarthy H, Wong G, Kairaitis L, Bose B, Harris DCH, Alexander SI. Membranous nephropathy: Clearer pathology and mechanisms identify potential strategies for treatment. Front Immunol 2022; 13:1036249. [PMID: 36405681 PMCID: PMC9667740 DOI: 10.3389/fimmu.2022.1036249] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 10/19/2022] [Indexed: 11/07/2022] Open
Abstract
Primary membranous nephropathy (PMN) is one of the common causes of adult-onset nephrotic syndrome and is characterized by autoantibodies against podocyte antigens causing in situ immune complex deposition. Much of our understanding of the disease mechanisms underpinning this kidney-limited autoimmune disease originally came from studies of Heymann nephritis, a rat model of PMN, where autoantibodies against megalin produced a similar disease phenotype though megalin is not implicated in human disease. In PMN, the major target antigen was identified to be M-type phospholipase A2 receptor 1 (PLA2R) in 2009. Further utilization of mass spectrometry on immunoprecipitated glomerular extracts and laser micro dissected glomeruli has allowed the rapid discovery of other antigens (thrombospondin type-1 domain-containing protein 7A, neural epidermal growth factor-like 1 protein, semaphorin 3B, protocadherin 7, high temperature requirement A serine peptidase 1, netrin G1) targeted by autoantibodies in PMN. Despite these major advances in our understanding of the pathophysiology of PMN, treatments remain non-specific, often ineffective, or toxic. In this review, we summarize our current understanding of the immune mechanisms driving PMN from animal models and clinical studies, and the implications on the development of future targeted therapeutic strategies.
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Affiliation(s)
- Edmund Y. M. Chung
- Centre for Kidney Research, The Children’s Hospital at Westmead, Westmead, NSW, Australia
| | - Yuan M. Wang
- Centre for Kidney Research, The Children’s Hospital at Westmead, Westmead, NSW, Australia
| | - Karen Keung
- Department of Nephrology, Prince of Wales Hospital, Randwick, NSW, Australia
| | - Min Hu
- The Centre for Transplant and Renal Research, Westmead Institute of Medical Research, Westmead, NSW, Australia
| | - Hugh McCarthy
- Centre for Kidney Research, The Children’s Hospital at Westmead, Westmead, NSW, Australia
- Department of Nephrology, The Children’s Hospital at Westmead, Westmead, NSW, Australia
- Department of Nephrology, Sydney Children’s Hospital, Randwick, NSW, Australia
| | - Germaine Wong
- Centre for Kidney Research, The Children’s Hospital at Westmead, Westmead, NSW, Australia
- Department of Nephrology, Westmead Hospital, Westmead, NSW, Australia
| | - Lukas Kairaitis
- Department of Nephrology, Blacktown Hospital, Blacktown, NSW, Australia
| | - Bhadran Bose
- Department of Nephrology, Nepean Hospital, Kingswood, NSW, Australia
| | - David C. H. Harris
- The Centre for Transplant and Renal Research, Westmead Institute of Medical Research, Westmead, NSW, Australia
- Department of Nephrology, Westmead Hospital, Westmead, NSW, Australia
| | - Stephen I. Alexander
- Centre for Kidney Research, The Children’s Hospital at Westmead, Westmead, NSW, Australia
- Department of Nephrology, The Children’s Hospital at Westmead, Westmead, NSW, Australia
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Liu W, Gao C, Dai H, Zheng Y, Dong Z, Gao Y, Liu F, Zhang Z, Liu Z, Liu W, Liu B, Liu Q, Shi J. Immunological Pathogenesis of Membranous Nephropathy: Focus on PLA2R1 and Its Role. Front Immunol 2019; 10:1809. [PMID: 31447839 PMCID: PMC6691064 DOI: 10.3389/fimmu.2019.01809] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 07/17/2019] [Indexed: 12/30/2022] Open
Abstract
Membranous nephropathy (MN) is the major cause of nephrotic syndrome with special pathological features, caused by the formation of immune complexes in the space between podocytes and the glomerular basement membrane. In idiopathic membranous nephropathy (IMN) the immune complexes are formed by circulating antibodies binding mainly to one of two naturally-expressed podocyte antigens: the M-type receptor for secretory phospholipase A2 (PLA2R1) and the Thrombospondin type-1 domain-containing 7A (THSD7A). Formation of antibodies against PLA2R1 is much more common, accounting for 70-80% of IMN. However, the mechanism of anti-podocyte antibody production in IMN is still unclear. In this review, we emphasize that the exposure of PLA2R1 is critical for triggering the pathogenesis of PLA2R1-associated MN, and propose the potential association between inflammation, pollution and PLA2R1. Our review aims to clarify the current research of these precipitating factors in a way that may suggest future directions for discovering the pathogenesis of MN, leading to additional therapeutic targets and strategies for the prevention and early treatment of MN.
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Affiliation(s)
- Wenbin Liu
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, China.,Capital Medical University, Beijing, China
| | - Chang Gao
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, China.,Beijing University of Chinese Medicine, Beijing, China
| | - Haoran Dai
- Shunyi Branch, Beijing Hospital of Traditional Chinese Medicine, Beijing, China
| | - Yang Zheng
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, China
| | - Zhaocheng Dong
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, China.,Beijing University of Chinese Medicine, Beijing, China
| | - Yu Gao
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, China.,Capital Medical University, Beijing, China
| | - Fei Liu
- Beijing University of Chinese Medicine, Beijing, China
| | - Zihan Zhang
- Beijing University of Chinese Medicine, Beijing, China
| | | | - Weijing Liu
- Key Laboratory of Chinese Internal Medicine of Ministry of Education, Beijing, China
| | - Baoli Liu
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, China
| | - Qingquan Liu
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing, China
| | - Jialan Shi
- Departments of Medicine, VA Boston Healthcare System, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
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Kim HJ, Liyanage OT, Mulenos MR, Gallagher ES. Mass Spectral Detection of Forward- and Reverse-Hydrogen/Deuterium Exchange Resulting from Residual Solvent Vapors in Electrospray Sources. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:2030-2040. [PMID: 29998361 DOI: 10.1007/s13361-018-2019-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/23/2018] [Accepted: 06/23/2018] [Indexed: 05/22/2023]
Abstract
Characterizing glycans is analytically challenging since glycans are heterogeneous, branched polymers with different three-dimensional conformations. Hydrogen/deuterium exchange-mass spectrometry (HDX-MS) has been used to analyze native conformations and dynamics of biomolecules by measuring the mass increase of analytes as labile protons are replaced with deuterium following exposure to deuterated solvents. The rate of exchange is dependent on the chemical functional group, the presence of hydrogen bonds, pH, temperature, charge, and solvent accessibility. HDX-MS of carbohydrates is challenging due to the rapid exchange rate of hydroxyls. Here, we describe an observed HDX reaction associated with residual solvent vapors saturating electrospray sources. When undeuterated melezitose was infused after infusing D2O, samples with up to 73% deuterium exchange were detected. This residual solvent HDX was observed for both carbohydrates and peptides in multiple instruments and dependent on sample infusion rate, infusion time, and deuterium content of the solvent. This residual solvent HDX was observed over several minutes of sample analysis and persisted long enough to alter the measured deuterium labeling and possibly change the interpretation of the results. This work illustrates that residual solvent HDX competes with in-solution HDX for rapidly exchanging functional groups. Thus, we propose conditions to minimize this effect, specifically for top-down, in-electrospray ionization, and quench-flow HDX experiments. Graphical Abstract ᅟ.
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Affiliation(s)
- H Jamie Kim
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA
| | - O Tara Liyanage
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA
| | - Marina R Mulenos
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA
| | - Elyssia S Gallagher
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA.
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Seitz-Polski B, Lambeau G, Esnault V. [Membranous nephropathy: Pathophysiology and natural history]. Nephrol Ther 2018; 13 Suppl 1:S75-S81. [PMID: 28577747 DOI: 10.1016/j.nephro.2017.01.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 01/17/2017] [Indexed: 10/19/2022]
Abstract
Membranous nephropathy is a major cause of nephrotic syndrome in adults, with various etiologies and outcomes. One third of patients enter spontaneous remission with blockade of the renin-angiotensin system, one third develop a persistent nephrotic syndrome, while another third of patients develop end-stage kidney disease and 40% of them relapse after kidney transplantation. Treatment of membranous nephropathy remains controversial. Immunosuppressive therapy is only recommended in case of renal function deterioration or persistent nephrotic syndrome after 6months of renin-angiotensin system blockade. Therefore, delayed immunosuppressive treatments may lead to significant and potentially irreversible complications. For long, no biological markers could predict clinical outcome and guide therapy. The discovery of autoantibodies to the phospholipase A2 receptor (PLA2R1) in 2009, and to the thrombospondin type 1 domain containing 7A (THSD7A) in 2014 in respectively 70 and 5% of patients with membranous nephropathy were major breakthroughs. The passive infusion of human anti-THSD7A antibodies in mouse induces proteinuria and membranous nephropathy. The identification of these antigens has allowed developing diagnostic and prognostic tests. High anti-PLA2R1 titers at time of diagnosis predict a poor renal outcome. Anti-PLA2R1 antibodies can bind at least three different domains of PLA2R1. Epitope spreading with binding of two or three of these antigenic domains is associated with active membranous nephropathy and poor renal survival. These new tools could help us to monitor disease severity and to predict renal prognosis for a better selection of patients that should benefit of early immunosuppressive therapy.
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Affiliation(s)
- Barbara Seitz-Polski
- Laboratoire d'immunologie, hôpital l'Archet, CHU de Nice, université de Nice-Sophia Antipolis, 06202 Nice cedex 3, France; UMR 7275, institut de pharmacologie moléculaire et cellulaire, CNRS, Sophia Antipolis, 660, route des Lucioles, 06560 Valbonne, France; Service de néphrologie, hôpital Pasteur, université de Nice-Sophia Antipolis, CHU de Nice, 30, voie romaine, CS 51069, 06001 Nice cedex 1, France.
| | - Gérard Lambeau
- UMR 7275, institut de pharmacologie moléculaire et cellulaire, CNRS, Sophia Antipolis, 660, route des Lucioles, 06560 Valbonne, France
| | - Vincent Esnault
- Service de néphrologie, hôpital Pasteur, université de Nice-Sophia Antipolis, CHU de Nice, 30, voie romaine, CS 51069, 06001 Nice cedex 1, France
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5
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Ronco P, Debiec H. A podocyte view of membranous nephropathy: from Heymann nephritis to the childhood human disease. Pflugers Arch 2017; 469:997-1005. [PMID: 28597189 DOI: 10.1007/s00424-017-2007-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 05/25/2017] [Indexed: 10/25/2022]
Abstract
Membranous nephropathy (MN) is characterized by an accumulation of immune deposits on the subepithelial side of the glomerular basement membrane, which results in complement activation and proteinuria. Since 2002, several major antigens of the podocyte have been identified in human MN, the first one being neutral endopeptidase (NEP), the alloantigen involved in neonatal cases of MN that occur in newborns from NEP-deficient mothers. This discovery opened the field to the major advances that have occurred since then in the pathophysiology and treatment of MN. It is remarkable that experimental models such as Heymann nephritis and cationic bovine serum albumin-induced MN in the rabbit predicted the pathomechanisms of the human glomerulopathy. The podocyte is at the center of the pathogenesis of MN either by providing a source of endogenous antigens or by creating an environment favorable to deposition and accumulation of immune complexes containing exogenous (non-podocyte) antigens. The podocyte is also a victim of complement activation and antibody blocking activity against enzymes or receptors. A search for innovative drugs aimed at protecting this cell against complement activation and the effects of prolonged ER stress has become a priority.
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Affiliation(s)
- Pierre Ronco
- Inserm UMR_S 1155, Hôpital Tenon, 4 rue de la Chine, 75020, Paris, France. .,Sorbonne Universités, UPMC Univ Paris 06, 75005, Paris, France. .,AP-HP, Hôpital Tenon, Service de Néphrologie et Dialyses, Paris, France.
| | - Hanna Debiec
- Inserm UMR_S 1155, Hôpital Tenon, 4 rue de la Chine, 75020, Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, 75005, Paris, France
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Ronco P, Debiec H. Pathogenesis of membranous nephropathy: recent advances and future challenges. Nat Rev Nephrol 2012; 8:203-13. [DOI: 10.1038/nrneph.2012.35] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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7
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Abstract
For more than 50 years researchers have debated the evidence for an autoimmune basis of human idiopathic membranous nephritis (MN). Work published in the past 2 years has substantially strengthened the belief that MN is indeed an autoimmune disease of the kidney. Autoantibodies of the IgG4 subclass to at least three podocyte membrane proteins including phospholipase A(2)-receptor, aldose reductase, and manganese superoxide dismutase have been detected by immunoblotting in sera as well as in acid eluates prepared from renal biopsy tissue of patients with this disease, using either whole tissue or microdissected glomeruli from frozen sections. In each case the podocyte antigen has been shown to co-localize with the subepithelial glomerular immune deposits in renal tissue of the same patients. It is not certain if any of these podocyte proteins is an inciting/primary autoantigen or whether they are secondary antigens recruited by intermolecular epitope-spreading, initiating from a yet-to-be-discovered autoantigen. Although it is clear that autoantibodies to podocyte membrane proteins are elicited in idiopathic MN and contribute to the formation of the subepithelial deposits, many questions remain concerning the triggers for their development and their contribution toward proteinuria and progression of the disease.
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Janas T, Janas T. Membrane oligo- and polysialic acids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2923-32. [DOI: 10.1016/j.bbamem.2011.08.036] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 08/29/2011] [Accepted: 08/31/2011] [Indexed: 10/17/2022]
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9
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Glassock RJ. The Pathogenesis of Idiopathic Membranous Nephropathy: A 50-Year Odyssey. Am J Kidney Dis 2010; 56:157-67. [PMID: 20378220 DOI: 10.1053/j.ajkd.2010.01.008] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Accepted: 01/13/2010] [Indexed: 11/11/2022]
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10
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Shah P, Tramontano A, Makker SP. Intramolecular epitope spreading in Heymann nephritis. J Am Soc Nephrol 2007; 18:3060-6. [PMID: 18003776 DOI: 10.1681/asn.2007030342] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Immunization with megalin induces active Heymann nephritis, which reproduces features of human idiopathic membranous glomerulonephritis. Megalin is a complex immunological target with four discrete ligand-binding domains (LBDs) that may contain epitopes to which pathogenic autoantibodies are directed. Recently, a 236-residue N-terminal fragment, termed "L6," that spans the first LBD was shown to induce autoantibodies and severe disease. We used this model to examine epitope-specific contributions to pathogenesis. Sera obtained from rats 4 weeks after immunization with L6 demonstrated reactivity only with the L6 fragment on Western blot, whereas sera obtained after 8 weeks demonstrated reactivity with all four recombinant fragments of interest (L6 and LBDs II, III, and IV). We demonstrated that the L6 immunogen does not contain the epitopes responsible for the reactivity to the LBD fragments. Therefore, the appearance of antibodies directed at LBD fragments several weeks after the primary immune response suggests intramolecular epitope spreading. In vivo, we observed a temporal association between increased proteinuria and the appearance of antibodies to LBD fragments. These data implicate B cell epitope spreading in antibody-mediated pathogenesis of active Heymann nephritis, a model that should prove valuable for further study of autoimmune dysregulation.
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Affiliation(s)
- Pallavi Shah
- Department of Pediatrics, University of California, Davis, School of Medicine, Davis, California 95616, USA
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11
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Ronco P, Debiec H. Target antigens and nephritogenic antibodies in membranous nephropathy: of rats and men. Semin Immunopathol 2007; 29:445-58. [PMID: 17899086 DOI: 10.1007/s00281-007-0091-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 08/17/2007] [Indexed: 01/31/2023]
Abstract
Membranous nephropathy, a disease characterized by an accumulation of immune deposits on the outer aspect of the glomerular basement membrane, is the most common cause of idiopathic nephrotic syndrome in white adults. In the rat model of Heymann nephritis, the target antigen of antibodies is megalin, a multiligand receptor expressed at the podocyte cell surface. This review summarizes key findings provided by this experimental model and by our discovery of neutral endopeptidase being the alloantigen involved in neonatal cases of membranous nephropathy. We discuss the role of alloimmunization as a new mechanism of renal disease and the approach that we use to identify new podocyte antigens. We also summarize current knowledge on the mechanism of proteinuria, with special emphasis on the role of complement. In conclusion, substantial progresses have been made in understanding molecular mechanisms of membranous nephropathy, which should lead to novel therapeutic approaches.
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Affiliation(s)
- P Ronco
- INSERM Unit 702, Hôpital Tenon, 4 rue de la Chine, 75020, Paris, France.
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Ehrlich JR, Caiazzo RJ, Qiu W, Tassinari OW, O'Leary MP, Richie JP, Liu BCS. A native antigen “reverse capture” microarray platform for autoantibody profiling of prostate cancer sera. Proteomics Clin Appl 2007; 1:476-85. [DOI: 10.1002/prca.200700012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Indexed: 11/11/2022]
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13
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Ronco P, Debiec H. Molecular dissection of target antigens and nephritogenic antibodies in membranous nephropathy: towards epitope-driven therapies. J Am Soc Nephrol 2006; 17:1772-4. [PMID: 16775025 DOI: 10.1681/asn.2006050497] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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14
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Tramontano A, Knight T, Vizzuso D, Makker SP. Nested N-terminal megalin fragments induce high-titer autoantibody and attenuated Heymann nephritis. J Am Soc Nephrol 2006; 17:1979-85. [PMID: 16762989 DOI: 10.1681/asn.2005101144] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
It was shown previously that an N-terminal fragment (nM60) that encompasses amino acid residues 1 to 563 of megalin could induce active Heymann nephritis (AHN) as efficiently as the native protein. For delineation of a minimal structure within this fragment that is sufficient to induce AHN, smaller protein fragments that encompass residues 1 to 236 (L6), 1 to 195 (L5), 1 to 156 (L4), and 1 to 120 (L3), representing successive C-terminal truncations within ligand-binding repeats of nM60, were cloned and produced in a baculovirus insect cell expression system. Protein fragments L4, L5, and L6 clearly were glycosylated. All four fragments stimulated proliferation of megalin-sensitized lymph node cells and induced high-titer anti-megalin autoantibodies in Lewis rats. A full-blown disease, as assessed by severity of proteinuria, was observed in rats that were immunized with L6 and L5, whereas animals that were immunized with L4 and L3 developed only mild disease. The proteinuria levels correlated with staining for complement (C3, C5b-9) and IgG1 isotype in glomerular immune deposits. The results suggest that one or more molecular determinants on the region that comprises amino acid residues 157 to 236 contribute to the induction of a full-blown form of AHN. Study of the structure, conformation, and posttranslational modifications of these determinants could provide greater insight into the molecular correlates of immunopathogenesis in this disease model.
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Affiliation(s)
- Alfonso Tramontano
- Department of Pediatrics, University of California, Davis, School of Medicine, 1 Shields Avenue, Davis, CA 95616, USA
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15
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Giersing B, Miura K, Shimp R, Wang J, Zhou H, Orcutt A, Stowers A, Saul A, Miller LH, Long C, Singh S. posttranslational modification of recombinant Plasmodium falciparum apical membrane antigen 1: impact on functional immune responses to a malaria vaccine candidate. Infect Immun 2005; 73:3963-70. [PMID: 15972483 PMCID: PMC1168543 DOI: 10.1128/iai.73.7.3963-3970.2005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2005] [Revised: 02/14/2005] [Accepted: 03/06/2005] [Indexed: 01/06/2023] Open
Abstract
Recombinant apical membrane antigen 1 (AMA1) is a leading vaccine candidate for Plasmodium falciparum malaria, as antibodies against recombinant P. falciparum AMA1 (PfAMA1) interrupt merozoite invasion into erythrocytes. In order to investigate the role of posttranslational modification in modulating the functional immune response to recombinant AMA1, two separate alleles of PfAMA1 (FVO and 3D7), in which native N-glycosylation sites have been mutated, were produced using Escherichia coli and a Pichia pastoris expression system. Recombinant Pichia pastoris AMA1-FVO (PpAMA1-FVO) and PpAMA1-3D7 are O-linked glycosylated, and 45% of PpAMA1-3D7 is nicked, though all four recombinant molecules react with conformation-specific monoclonal antibodies. To address the immunological effect of O-linked glycosylation, we compared the immunogenicity of E. coli AMA1-FVO (EcAMA1-FVO) and PpAMA1-FVO antigens, since both molecules are intact. The effect of antigen nicking was then investigated by comparing the immunogenicity of EcAMA1-3D7 and PpAMA1-3D7. Our data demonstrate that there is no significant difference in the rabbit antibody titer elicited towards EcAMA1-FVO and PpAMA1-FVO or to EcAMA1-3D7 and PpAMA1-3D7. Furthermore, we have demonstrated that recombinant AMA1 (FVO or 3D7), whether expressed and refolded from E. coli or produced from the Pichia expression system, is equivalent and mimics the functionality of the native protein in in vitro growth inhibition assay experiments. We conclude that in the case of recombinant AMA1, the E. coli- and P. pastoris-derived antigens are immunologically and functionally equivalent and are unaffected by the posttranslational modification resulting from expression in these two systems.
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Affiliation(s)
- Birgitte Giersing
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Twinbrook I, Room 1210A, 5640 Fisher Lane, Rockville, Maryland 20852, USA
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16
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Abstract
Adaptive immune responses have long been considered the "territory" of antigenic proteins, whereas carbohydrates are characterized as T-cell-independent antigens that are not typically recognized by the complete adaptive machinery. The current modus operandi when searching for dominant epitopes is the use of synthetic peptides designed from the primary structure of interesting target proteins; however, there is growing evidence that sugars can also play a critical role in immune recognition. Findings reported in this issue of the European Journal of Immunology begin to shed light on the differences in protein glycosylation that can occur in association with disorders like rheumatoid arthritis and the effect these changes have on collagen recognition by the immune system. Other recent studies have shown that immunodominant glycopeptide "remnant" epitopes as well as glycosylation changes on self-proteins can generate autoimmunity. Finally, some types of carbohydrates are now known to be processed and presented to T cells by class II MHC. Taken together, these advances illustrate a clear importance for carbohydrate recognition in foreign and self antigens by the adaptive immune system. With the common presence of carbohydrate molecules on eukaryotic, prokaryotic, and viral surfaces, the impact of carbohydrates on adaptive immunity is now indisputable.
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Affiliation(s)
- Brian A Cobb
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
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