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Kremer PG, Lampros EA, Blocker AM, Barb AW. One N-glycan regulates natural killer cell antibody-dependent cell-mediated cytotoxicity and modulates Fc γ receptor IIIa / CD16a structure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.17.599285. [PMID: 38948809 PMCID: PMC11212880 DOI: 10.1101/2024.06.17.599285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
Both endogenous antibodies and a subset of antibody therapeutics engage Fc gamma receptor (FcγR)IIIa / CD16a to stimulate a protective immune response. Increasing the FcγRIIIa/IgG1 interaction improves the immune response and thus represents a strategy to improve therapeutic efficacy. FcγRIIIa is a heavily glycosylated receptor and glycan composition affects antibody-binding affinity. Though our laboratory previously demonstrated that natural killer (NK) cell N-glycan composition affected the potency of one key protective mechanism, antibody-dependent cell-mediated cytotoxicity (ADCC), it was unclear if this effect was due to FcγRIIIa glycosylation. Furthermore, the structural mechanism linking glycan composition to affinity and cellular activation remained undescribed. To define the role of individual amino acid and N-glycan residues we measured affinity using multiple FcγRIIIa glycoforms. We observed stepwise affinity increases with each glycan truncation step with the most severely truncated glycoform displaying the highest affinity. Removing the N162 glycan demonstrated its predominant role in regulating antibody-binding affinity, in contrast to four other FcγRIIIa N-glycans. We next evaluated the impact of the N162 glycan on NK cell ADCC. NK cells expressing the FcγRIIIa V158 allotype exhibited increased ADCC following kifunensine treatment to limit N-glycan processing. Notably, an increase was not observed with cells expressing the FcγRIIIa V158 S164A variant that lacks N162 glycosylation, indicating the N162 glycan is required for increased NK cell ADCC. To gain structural insight into the mechanisms of N162 regulation, we applied a novel protein isotope labeling approach in combination with solution NMR spectroscopy. FG loop residues proximal to the N162 glycosylation site showed large chemical shift perturbations following glycan truncation. These data support a model for the regulation of FcγRIIIa affinity and NK cell ADCC whereby composition of the N162 glycan stabilizes the FG loop and thus the antibody-binding site.
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Chang YH, Hsu MF, Chen WN, Wu MH, Kong WL, Lu MYJ, Huang CH, Chang FJ, Chang LY, Tsai HY, Tung CP, Yu JH, Kuo Y, Chou YC, Bai LY, Chang YC, Chen AY, Chen CC, Chen YH, Liao CC, Chang CS, Liang JJ, Lin YL, Angata T, Hsu STD, Lin KI. Functional and structural investigation of a broadly neutralizing SARS-CoV-2 antibody. JCI Insight 2024; 9:e179726. [PMID: 38775156 PMCID: PMC11141937 DOI: 10.1172/jci.insight.179726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 04/12/2024] [Indexed: 06/02/2024] Open
Abstract
Since its emergence, SARS-CoV-2 has been continuously evolving, hampering the effectiveness of current vaccines against COVID-19. mAbs can be used to treat patients at risk of severe COVID-19. Thus, the development of broadly protective mAbs and an understanding of the underlying protective mechanisms are of great importance. Here, we isolated mAbs from donors with breakthrough infection with Omicron subvariants using a single-B cell screening platform. We identified a mAb, O5C2, which possesses broad-spectrum neutralization and antibody-dependent cell-mediated cytotoxic activities against SARS-CoV-2 variants, including EG.5.1. Single-particle analysis by cryo-electron microscopy revealed that O5C2 targeted an unusually large epitope within the receptor-binding domain of spike protein that overlapped with the angiotensin-converting enzyme 2 binding interface. Furthermore, O5C2 effectively protected against BA.5 Omicron infection in vivo by mediating changes in transcriptomes enriched in genes involved in apoptosis and interferon responses. Our findings provide insights into the development of pan-protective mAbs against SARS-CoV-2.
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Affiliation(s)
- Yi-Hsuan Chang
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | | | - Wei-Nan Chen
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | | | - Wye-Lup Kong
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Mei-Yeh Jade Lu
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Chih-Heng Huang
- Institute of Preventive Medicine
- Graduate Institute of Medical Sciences, and
- Department of Microbiology and Immunology, National Defense Medical Center, Taipei, Taiwan
| | - Fang-Ju Chang
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | | | - Ho-Yang Tsai
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Chao-Ping Tung
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Jou-Hui Yu
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Yali Kuo
- Biomedical Translation Research Center (BioTReC)
| | - Yu-Chi Chou
- Biomedical Translation Research Center (BioTReC)
| | - Li-Yang Bai
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
| | - Yuan-Chih Chang
- Institute of Biological Chemistry and
- Academia Sinica Cryo-EM Center, and
| | - An-Yu Chen
- Institute of Preventive Medicine
- Graduate Institute of Medical Sciences, and
| | - Cheng-Cheung Chen
- Institute of Preventive Medicine
- Graduate Institute of Medical Sciences, and
| | - Yi-Hua Chen
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | | | | | - Jian-Jong Liang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yi-Ling Lin
- Biomedical Translation Research Center (BioTReC)
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Takashi Angata
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
- Institute of Biological Chemistry and
| | - Shang-Te Danny Hsu
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
- Institute of Biological Chemistry and
- International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKC M2, ) Hiroshima University, Hiroshima, Japan
| | - Kuo-I Lin
- Genomics Research Center, Academia Sinica, Taipei, Taiwan
- Biomedical Translation Research Center (BioTReC)
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3
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Zhou X, Geyer FK, Happel D, Takimoto J, Kolmar H, Rabinovich B. Using protein geometry to optimize cytotoxicity and the cytokine window of a ROR1 specific T cell engager. Front Immunol 2024; 15:1323049. [PMID: 38455046 PMCID: PMC10917902 DOI: 10.3389/fimmu.2024.1323049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 02/05/2024] [Indexed: 03/09/2024] Open
Abstract
T cell engaging bispecific antibodies have shown clinical proof of concept for hematologic malignancies. Still, cytokine release syndrome, neurotoxicity, and on-target-off-tumor toxicity, especially in the solid tumor setting, represent major obstacles. Second generation TCEs have been described that decouple cytotoxicity from cytokine release by reducing the apparent binding affinity for CD3 and/or the TAA but the results of such engineering have generally led only to reduced maximum induction of cytokine release and often at the expense of maximum cytotoxicity. Using ROR1 as our model TAA and highly modular camelid nanobodies, we describe the engineering of a next generation decoupled TCE that incorporates a "cytokine window" defined as a dose range in which maximal killing is reached but cytokine release may be modulated from very low for safety to nearly that induced by first generation TCEs. This latter attribute supports pro-inflammatory anti-tumor activity including bystander killing and can potentially be used by clinicians to safely titrate patient dose to that which mediates maximum efficacy that is postulated as greater than that possible using standard second generation approaches. We used a combined method of optimizing TCE mediated synaptic distance and apparent affinity tuning of the TAA binding arms to generate a relatively long but persistent synapse that supports a wide cytokine window, potent killing and a reduced propensity towards immune exhaustion. Importantly, this next generation TCE induced significant tumor growth inhibition in vivo but unlike a first-generation non-decoupled benchmark TCE that induced lethal CRS, no signs of adverse events were observed.
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Affiliation(s)
- Xueyuan Zhou
- Drug Discovery and Development, Fuse Biotherapeutics, Woburn, MA, United States
| | - Felix Klaus Geyer
- Institute for Organic Chemistry and Biochemistry, Technical University of Darmstadt, Darmstadt, Germany
| | - Dominic Happel
- Institute for Organic Chemistry and Biochemistry, Technical University of Darmstadt, Darmstadt, Germany
| | - Jeffrey Takimoto
- Drug Discovery and Development, Fuse Biotherapeutics, Woburn, MA, United States
| | - Harald Kolmar
- Institute for Organic Chemistry and Biochemistry, Technical University of Darmstadt, Darmstadt, Germany
- Centre for Synthetic Biology, Technical University of Darmstadt, Darmstadt, Germany
| | - Brian Rabinovich
- Drug Discovery and Development, Fuse Biotherapeutics, Woburn, MA, United States
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4
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Seckinger A, Majocchi S, Moine V, Nouveau L, Ngoc H, Daubeuf B, Ravn U, Pleche N, Calloud S, Broyer L, Cons L, Lesnier A, Chatel L, Papaioannou A, Salgado-Pires S, Krämer S, Gockel I, Lordick F, Masternak K, Poitevin Y, Magistrelli G, Malinge P, Shang L, Kallendrusch S, Strein K, Hose D. Development and characterization of NILK-2301, a novel CEACAM5xCD3 κλ bispecific antibody for immunotherapy of CEACAM5-expressing cancers. J Hematol Oncol 2023; 16:117. [PMID: 38087365 PMCID: PMC10717981 DOI: 10.1186/s13045-023-01516-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 11/25/2023] [Indexed: 12/18/2023] Open
Abstract
BACKGROUND T-cell retargeting to eliminate CEACAM5-expressing cancer cells via CEACAM5xCD3 bispecific antibodies (BsAbs) showed limited clinical activity so far, mostly due to insufficient T-cell activation, dose-limiting toxicities, and formation of anti-drug antibodies (ADA). METHODS We present here the generation and preclinical development of NILK-2301, a BsAb composed of a common heavy chain and two different light chains, one kappa and one lambda, determining specificity (so-called κλ body format). RESULTS NILK-2301 binds CD3ɛ on T-cells with its lambda light chain arm with an affinity of ≈100 nM, and the CEACAM5 A2 domain on tumor cells by its kappa light chain arm with an affinity of ≈5 nM. FcγR-binding is abrogated by the "LALAPA" mutation (Leu234Ala, Leu235Ala, Pro329Ala). NILK-2301 induced T-cell activation, proliferation, cytokine release, and T-cell dependent cellular cytotoxicity of CEACAM5-positive tumor cell lines (5/5 colorectal, 2/2 gastric, 2/2 lung), e.g., SK-CO-1 (Emax = 89%), MKN-45 (Emax = 84%), and H2122 (Emax = 97%), with EC50 ranging from 0.02 to 0.14 nM. NILK-2301 binds neither to CEACAM5-negative or primary colon epithelial cells nor to other CEACAM family members. NILK-2301 alone or in combination with checkpoint inhibition showed activity in organotypic tumor tissue slices and colorectal cancer organoid models. In vivo, NILK-2301 at 10 mg/kg significantly delayed tumor progression in colon- and a pancreatic adenocarcinoma model. Single-dose pharmacokinetics (PK) and tolerability in cynomolgus monkeys at 0.5 or 10 mg/kg intravenously or 20 mg subcutaneously showed dose-proportional PK, bioavailability ≈100%, and a projected half-life in humans of 13.1 days. NILK-2301 was well-tolerated. Data were confirmed in human FcRn TG32 mice. CONCLUSIONS In summary, NILK-2301 combines promising preclinical activity and safety with lower probability of ADA-generation due to its format compared to other molecules and is scheduled to enter clinical testing at the end of 2023.
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Affiliation(s)
- Anja Seckinger
- LamKap Bio Alpha AG, Bahnhofstrasse 1, 8808, Pfäffikon, SZ, Switzerland
| | - Sara Majocchi
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Valéry Moine
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Lise Nouveau
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Hoang Ngoc
- Institute of Anatomy, Leipzig University, Liebigstrasse 13, 04103, Leipzig, Germany
| | - Bruno Daubeuf
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Ulla Ravn
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Nicolas Pleche
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Sebastien Calloud
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Lucile Broyer
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Laura Cons
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Adeline Lesnier
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Laurence Chatel
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Anne Papaioannou
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Susana Salgado-Pires
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Sebastian Krämer
- Department of Visceral, Transplantation, Thoracic and Vascular Surgery, University Hospital Leipzig, Liebigstrasse 20, 04103, Leipzig, Germany
| | - Ines Gockel
- Department of Visceral, Transplantation, Thoracic and Vascular Surgery, University Hospital Leipzig, Liebigstrasse 20, 04103, Leipzig, Germany
| | - Florian Lordick
- Department of Medicine II, University Cancer Center Leipzig (UCCL), Leipzig University Medical Center, Liebigstrasse 22, 04103, Leipzig, Germany
| | - Krzysztof Masternak
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Yves Poitevin
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Giovanni Magistrelli
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Pauline Malinge
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Limin Shang
- Light Chain Bioscience - Novimmune SA, Chemin du Pré-Fleuri 15, 1228, Plan-les-Ouates, Switzerland
| | - Sonja Kallendrusch
- Institute of Anatomy, Leipzig University, Liebigstrasse 13, 04103, Leipzig, Germany
- Institute of Clinical Research and System Medicine, Health and Medical University Potsdam, Schiffbauergasse 14, 14467, Potsdam, Germany
| | - Klaus Strein
- LamKap Bio Alpha AG, Bahnhofstrasse 1, 8808, Pfäffikon, SZ, Switzerland
| | - Dirk Hose
- LamKap Bio Alpha AG, Bahnhofstrasse 1, 8808, Pfäffikon, SZ, Switzerland.
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5
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Yan X, Ols S, Arcoverde Cerveira R, Lenart K, Hellgren F, Ye K, Cagigi A, Buggert M, Nimmerjahn F, Falkesgaard Højen J, Parera D, Pessara U, Fischer S, Loré K. Cell targeting and immunostimulatory properties of a novel Fcγ-receptor-independent agonistic anti-CD40 antibody in rhesus macaques. Cell Mol Life Sci 2023; 80:189. [PMID: 37353664 PMCID: PMC10289945 DOI: 10.1007/s00018-023-04828-2] [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: 02/20/2023] [Revised: 05/11/2023] [Accepted: 06/01/2023] [Indexed: 06/25/2023]
Abstract
Targeting CD40 by agonistic antibodies used as vaccine adjuvants or for cancer immunotherapy is a strategy to stimulate immune responses. The majority of studied agonistic anti-human CD40 antibodies require crosslinking of their Fc region to inhibitory FcγRIIb to induce immune stimulation although this has been associated with toxicity in previous studies. Here we introduce an agonistic anti-human CD40 monoclonal IgG1 antibody (MAB273) unique in its specificity to the CD40L binding site of CD40 but devoid of Fcγ-receptor binding. We demonstrate rapid binding of MAB273 to B cells and dendritic cells resulting in activation in vitro on human cells and in vivo in rhesus macaques. Dissemination of fluorescently labeled MAB273 after subcutaneous administration was found predominantly at the site of injection and specific draining lymph nodes. Phenotypic cell differentiation and upregulation of genes associated with immune activation were found in the targeted tissues. Antigen-specific T cell responses were enhanced by MAB273 when given in a prime-boost regimen and for boosting low preexisting responses. MAB273 may therefore be a promising immunostimulatory adjuvant that warrants future testing for therapeutic and prophylactic vaccination strategies.
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Affiliation(s)
- Xianglei Yan
- Division of Immunology and Allergy, Department of Medicine Solna, Karolinska Institutet and Karolinska University Hospital, Visionsgatan 4, BioClinicum J7:30, 171 64, Stockholm, Sweden
- Center of Molecular Medicine, Stockholm, Sweden
| | - Sebastian Ols
- Division of Immunology and Allergy, Department of Medicine Solna, Karolinska Institutet and Karolinska University Hospital, Visionsgatan 4, BioClinicum J7:30, 171 64, Stockholm, Sweden
- Center of Molecular Medicine, Stockholm, Sweden
| | - Rodrigo Arcoverde Cerveira
- Division of Immunology and Allergy, Department of Medicine Solna, Karolinska Institutet and Karolinska University Hospital, Visionsgatan 4, BioClinicum J7:30, 171 64, Stockholm, Sweden
- Center of Molecular Medicine, Stockholm, Sweden
| | - Klara Lenart
- Division of Immunology and Allergy, Department of Medicine Solna, Karolinska Institutet and Karolinska University Hospital, Visionsgatan 4, BioClinicum J7:30, 171 64, Stockholm, Sweden
- Center of Molecular Medicine, Stockholm, Sweden
| | - Fredrika Hellgren
- Division of Immunology and Allergy, Department of Medicine Solna, Karolinska Institutet and Karolinska University Hospital, Visionsgatan 4, BioClinicum J7:30, 171 64, Stockholm, Sweden
- Center of Molecular Medicine, Stockholm, Sweden
| | - Kewei Ye
- Division of Immunology and Allergy, Department of Medicine Solna, Karolinska Institutet and Karolinska University Hospital, Visionsgatan 4, BioClinicum J7:30, 171 64, Stockholm, Sweden
- Center of Molecular Medicine, Stockholm, Sweden
| | - Alberto Cagigi
- Division of Immunology and Allergy, Department of Medicine Solna, Karolinska Institutet and Karolinska University Hospital, Visionsgatan 4, BioClinicum J7:30, 171 64, Stockholm, Sweden
- Center of Molecular Medicine, Stockholm, Sweden
| | - Marcus Buggert
- Department of Medicine Huddinge, Center for Infectious Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Falk Nimmerjahn
- Division of Genetics, Department of Biology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Jesper Falkesgaard Højen
- Department of Infectious Diseases, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- Department of Medicine, University of Colorado Denver, Aurora, CO, USA
| | | | | | | | - Karin Loré
- Division of Immunology and Allergy, Department of Medicine Solna, Karolinska Institutet and Karolinska University Hospital, Visionsgatan 4, BioClinicum J7:30, 171 64, Stockholm, Sweden.
- Center of Molecular Medicine, Stockholm, Sweden.
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6
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Zhang F, Jenkins J, de Carvalho RVH, Nakandakari-Higa S, Chen T, Abernathy ME, Baharani VA, Nyakatura EK, Andrew D, Lebedeva IV, Lorenz IC, Hoffmann HH, Rice CM, Victora GD, Barnes CO, Hatziioannou T, Bieniasz PD. Pan-sarbecovirus prophylaxis with human anti-ACE2 monoclonal antibodies. Nat Microbiol 2023; 8:1051-1063. [PMID: 37188812 PMCID: PMC10234812 DOI: 10.1038/s41564-023-01389-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 04/19/2023] [Indexed: 05/17/2023]
Abstract
Human monoclonal antibodies (mAbs) that target the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein have been isolated from convalescent individuals and developed into therapeutics for SARS-CoV-2 infection. However, therapeutic mAbs for SARS-CoV-2 have been rendered obsolete by the emergence of mAb-resistant virus variants. Here we report the generation of a set of six human mAbs that bind the human angiotensin-converting enzyme-2 (hACE2) receptor, rather than the SARS-CoV-2 spike protein. We show that these antibodies block infection by all hACE2 binding sarbecoviruses tested, including SARS-CoV-2 ancestral, Delta and Omicron variants at concentrations of ~7-100 ng ml-1. These antibodies target an hACE2 epitope that binds to the SARS-CoV-2 spike, but they do not inhibit hACE2 enzymatic activity nor do they induce cell-surface depletion of hACE2. They have favourable pharmacology, protect hACE2 knock-in mice against SARS-CoV-2 infection and should present a high genetic barrier to the acquisition of resistance. These antibodies should be useful prophylactic and treatment agents against any current or future SARS-CoV-2 variants and might be useful to treat infection with any hACE2-binding sarbecoviruses that emerge in the future.
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Affiliation(s)
- Fengwen Zhang
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, USA
| | - Jesse Jenkins
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, USA
| | | | | | - Teresia Chen
- Department of Biology, Stanford University, Stanford, CA, USA
| | | | - Viren A Baharani
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, USA
| | | | - David Andrew
- Tri-Institutional Therapeutics Discovery Institute, New York, NY, USA
| | - Irina V Lebedeva
- Tri-Institutional Therapeutics Discovery Institute, New York, NY, USA
| | - Ivo C Lorenz
- Tri-Institutional Therapeutics Discovery Institute, New York, NY, USA
| | - H-Heinrich Hoffmann
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, USA
| | - Charles M Rice
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, USA
| | - Gabriel D Victora
- Laboratory of Lymphocyte Dynamics, The Rockefeller University, New York, NY, USA
| | - Christopher O Barnes
- Department of Biology, Stanford University, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | | | - Paul D Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, USA.
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY, USA.
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7
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Kim M, Cheong Y, Lee J, Lim J, Byun S, Jang YH, Seong BL. A Host-Restricted Self-Attenuated Influenza Virus Provides Broad Pan-Influenza A Protection in a Mouse Model. Front Immunol 2021; 12:779223. [PMID: 34925355 PMCID: PMC8674563 DOI: 10.3389/fimmu.2021.779223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 11/15/2021] [Indexed: 11/13/2022] Open
Abstract
Influenza virus infections can cause a broad range of symptoms, form mild respiratory problems to severe and fatal complications. While influenza virus poses a global health threat, the frequent antigenic change often significantly compromises the protective efficacy of seasonal vaccines, further increasing the vulnerability to viral infection. Therefore, it is in great need to employ strategies for the development of universal influenza vaccines (UIVs) which can elicit broad protection against diverse influenza viruses. Using a mouse infection model, we examined the breadth of protection of the caspase-triggered live attenuated influenza vaccine (ctLAIV), which was self-attenuated by the host caspase-dependent cleavage of internal viral proteins. A single vaccination in mice induced a broad reactive antibody response against four different influenza viruses, H1 and rH5 (HA group 1) and H3 and rH7 subtypes (HA group 2). Notably, despite the lack of detectable neutralizing antibodies, the vaccination provided heterosubtypic protection against the lethal challenge with the viruses. Sterile protection was confirmed by the complete absence of viral titers in the lungs and nasal turbinates after the challenge. Antibody-dependent cellular cytotoxicity (ADCC) activities of non-neutralizing antibodies contributed to cross-protection. The cross-protection remained robust even after in vivo depletion of T cells or NK cells, reflecting the strength and breadth of the antibody-dependent effector function. The robust mucosal secretion of sIgA reflects an additional level of cross-protection. Our data show that the host-restricted designer vaccine serves an option for developing a UIV, providing pan-influenza A protection against both group 1 and 2 influenza viruses. The present results of potency and breadth of protection from wild type and reassortant viruses addressed in the mouse model by single immunization merits further confirmation and validation, preferably in clinically relevant ferret models with wild type challenges.
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Affiliation(s)
- Minjin Kim
- Graduate Program in Biomaterials Science and Engineering, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Yucheol Cheong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Jinhee Lee
- Department of Integrated OMICS for Biomedical Science, College of Life science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Jongkwan Lim
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Sanguine Byun
- Graduate Program in Biomaterials Science and Engineering, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea.,Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Yo Han Jang
- Department of Biological Sciences and Biotechnology Major in Bio-Vaccine Engineering, Andong National University, Andong, South Korea.,Vaccine Industry Research Institute, Andong National University, Andong, South Korea
| | - Baik Lin Seong
- Department of Microbiology, College of Medicine, Yonsei University, Seoul, South Korea.,Vaccine Innovative Technology ALliance (VITAL)-Korea, Yonsei University, Seoul, South Korea
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8
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Tang Y, Cain P, Anguiano V, Shih JJ, Chai Q, Feng Y. Impact of IgG subclass on molecular properties of monoclonal antibodies. MAbs 2021; 13:1993768. [PMID: 34763607 PMCID: PMC8726687 DOI: 10.1080/19420862.2021.1993768] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Immunoglobulin G-based monoclonal antibodies (mAbs) have become a dominant class of biotherapeutics in recent decades. Approved antibodies are mainly of the subclasses IgG1, IgG2, and IgG4, as well as their derivatives. Over the decades, the selection of IgG subclass has frequently been based on the needs of Fc gamma receptor engagement and effector functions for the desired mechanism of action, while the effect on drug product developability has been less thoroughly characterized. One of the major reasons is the lack of systematic understanding of the impact of IgG subclass on the molecular properties. Several efforts have been made recently to compare molecular property differences among these IgG subclasses, but the conclusions from these studies are sometimes obscured by the interference from variable regions. To further establish mechanistic understandings, we conducted a systematic study by grafting three independent variable regions onto human IgG1, an IgG1 variant, IgG2, and an IgG4 variant constant domains and evaluating the impact of subclass and variable regions on their molecular properties. Structural and computational analysis revealed specific molecular features that potentially account for the differential behavior of the IgG subclasses observed experimentally. Our data indicate that IgG subclass plays a significant role on molecular properties, either through direct effects or via the interplay with the variable region, the IgG1 mAbs tend to have higher solubility than either IgG2 or IgG4 mAbs in a common pH 6 buffer matrix, and solution behavior relies heavily on the charge status of the antibody at the desirable pH.
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Affiliation(s)
- Yu Tang
- Pharmaceutical Development, Syndax Pharmaceuticals, Waltham, Massachusetts, USA
| | - Paul Cain
- Biotechnology Discovery Research, Lilly Research Laboratories, Lilly Technology Center North, Indianapolis, Indiana, USA
| | - Victor Anguiano
- Bioproduct Research & Development, Lilly Research Laboratories, Lilly Technology Center North, Indianapolis, Indiana, USA
| | - James J Shih
- Biotechnology Discovery Research, Lilly Research Laboratories, Lilly Biotechnology Center, San Diego, California, USA
| | - Qing Chai
- Biotechnology Discovery Research, Lilly Research Laboratories, Lilly Biotechnology Center, San Diego, California, USA
| | - Yiqing Feng
- Biotechnology Discovery Research, Lilly Research Laboratories, Lilly Technology Center North, Indianapolis, Indiana, USA
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9
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Cheong Y, Kim M, Ahn J, Oh H, Lim J, Chae W, Yang SW, Kim MS, Yu JE, Byun S, Jang YH, Seong BL. Epigallocatechin-3-Gallate as a Novel Vaccine Adjuvant. Front Immunol 2021; 12:769088. [PMID: 34868027 PMCID: PMC8632720 DOI: 10.3389/fimmu.2021.769088] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/28/2021] [Indexed: 12/22/2022] Open
Abstract
Vaccine adjuvants from natural resources have been utilized for enhancing vaccine efficacy against infectious diseases. This study examined the potential use of catechins, polyphenolic materials derived from green tea, as adjuvants for subunit and inactivated vaccines. Previously, catechins have been documented to have irreversible virucidal function, with the possible applicability in the inactivated viral vaccine platform. In a mouse model, the coadministration of epigallocatechin-3-gallate (EGCG) with influenza hemagglutinin (HA) antigens induced high levels of neutralizing antibodies, comparable to that induced by alum, providing complete protection against the lethal challenge. Adjuvant effects were observed for all types of HA antigens, including recombinant full-length HA and HA1 globular domain, and egg-derived inactivated split influenza vaccines. The combination of alum and EGCG further increased neutralizing (NT) antibody titers with the corresponding hemagglutination inhibition (HI) titers, demonstrating a dose-sparing effect. Remarkably, EGCG induced immunoglobulin isotype switching from IgG1 to IgG2a (approximately >64-700 fold increase), exerting a more balanced TH1/TH2 response compared to alum. The upregulation of IgG2a correlated with significant enhancement of antibody-dependent cellular cytotoxicity (ADCC) function (approximately 14 fold increase), providing a potent effector-mediated protection in addition to NT and HI. As the first report on a novel class of vaccine adjuvants with built-in virucidal activities, the results of this study will help improve the efficacy and safety of vaccines for pandemic preparedness.
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MESH Headings
- Adjuvants, Immunologic/administration & dosage
- Adjuvants, Vaccine/administration & dosage
- Alum Compounds/administration & dosage
- Animals
- Antibodies, Neutralizing/blood
- Antibodies, Neutralizing/immunology
- Antibodies, Viral/blood
- Antibodies, Viral/immunology
- Catechin/administration & dosage
- Catechin/analogs & derivatives
- Catechin/immunology
- Dogs
- Drug Synergism
- Female
- Hemagglutinin Glycoproteins, Influenza Virus/administration & dosage
- Hemagglutinin Glycoproteins, Influenza Virus/immunology
- Humans
- Immunoglobulin G/blood
- Immunoglobulin G/immunology
- Influenza A Virus, H1N1 Subtype/drug effects
- Influenza A Virus, H1N1 Subtype/immunology
- Influenza A Virus, H1N1 Subtype/physiology
- Influenza Vaccines/administration & dosage
- Influenza Vaccines/immunology
- Influenza, Human/immunology
- Influenza, Human/prevention & control
- Influenza, Human/virology
- Madin Darby Canine Kidney Cells
- Mice, Inbred BALB C
- Orthomyxoviridae Infections/immunology
- Orthomyxoviridae Infections/prevention & control
- Orthomyxoviridae Infections/virology
- Mice
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Affiliation(s)
- Yucheol Cheong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Minjin Kim
- Graduate Program in Biomaterials Science and Engineering, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Jina Ahn
- The Interdisciplinary Graduate Program in Integrative Biotechnology & Translational Medicine, Yonsei University, Incheon, South Korea
| | - Hana Oh
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Jongkwan Lim
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Wonil Chae
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Seung Won Yang
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Min Seok Kim
- Graduate Program in Biomaterials Science and Engineering, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Ji Eun Yu
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Sanguine Byun
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Yo Han Jang
- Department of Biological Sciences and Biotechnology Major in Bio-Vaccine Engineering, Andong National University, Andong, South Korea
- Vaccine Industry Research Institute, Andong National University, Andong, South Korea
| | - Baik Lin Seong
- Department of Microbiology, College of Medicine, Yonsei University, Seoul, South Korea
- Vaccine Innovative Technology ALliance (VITAL)-Korea, Yonsei University, Seoul, South Korea
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10
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Chua CLL, Ng IMJ, Yap BJM, Teo A. Factors influencing phagocytosis of malaria parasites: the story so far. Malar J 2021; 20:319. [PMID: 34271941 PMCID: PMC8284020 DOI: 10.1186/s12936-021-03849-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 07/07/2021] [Indexed: 12/16/2022] Open
Abstract
There are seven known species of Plasmodium spp. that can infect humans. The human host can mount a complex network of immunological responses to fight infection and one of these immune functions is phagocytosis. Effective and timely phagocytosis of parasites, accompanied by the activation of a regulated inflammatory response, is beneficial for parasite clearance. Functional studies have identified specific opsonins, particularly antibodies and distinct phagocyte sub-populations that are associated with clinical protection against malaria. In addition, cellular and molecular studies have enhanced the understanding of the immunological pathways and outcomes following phagocytosis of malaria parasites. In this review, an integrated view of the factors that can affect phagocytosis of infected erythrocytes and parasite components, the immunological consequences and their association with clinical protection against Plasmodium spp. infection is provided. Several red blood cell disorders and co-infections, and drugs that can influence phagocytic capability during malaria are also discussed. It is hoped that an enhanced understanding of this immunological process can benefit the design of new therapeutics and vaccines to combat this infectious disease.
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Affiliation(s)
| | - Ida May Jen Ng
- School of Biosciences, Taylor's University, Subang Jaya, Selangor, Malaysia
| | - Bryan Ju Min Yap
- School of Biosciences, Taylor's University, Subang Jaya, Selangor, Malaysia
| | - Andrew Teo
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore. .,Department of Medicine, The Doherty Institute, University of Melbourne, Victoria, Australia.
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11
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Lu J, Mold C, Du Clos TW, Sun PD. Pentraxins and Fc Receptor-Mediated Immune Responses. Front Immunol 2018; 9:2607. [PMID: 30483265 PMCID: PMC6243083 DOI: 10.3389/fimmu.2018.02607] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 10/23/2018] [Indexed: 12/27/2022] Open
Abstract
C-reactive protein (CRP) is a member of the pentraxin family of proteins. These proteins are highly conserved over the course of evolution being present as far back as 250 million years ago. Mammalian pentraxins are characterized by the presence of five identical non-covalently linked subunits. Each subunit has a structurally conserved site for calcium-dependent ligand binding. The biological activities of the pentraxins established over many years include the ability to mediate opsonization for phagocytosis and complement activation. Pentraxins have an important role in protection from infection from pathogenic bacteria, and regulation of the inflammatory response. It was recognized early on that some of these functions are mediated by activation of the classical complement pathway through C1q. However, experimental evidence suggested that cellular receptors for pentraxins also play a role in phagocytosis. More recent experimental evidence indicates a direct link between pentraxins and Fc receptors. The Fc receptors were first identified as the major receptors for immunoglobulins. The avidity of the interaction between IgG complexes and Fc receptors is greatly enhanced when multivalent ligands interact with the IgG binding sites and activation of signaling pathways requires Fc receptor crosslinking. Human pentraxins bind and activate human and mouse IgG receptors, FcγRI and FcγRII, and the human IgA receptor, FcαRI. The affinities of the interactions between Fc receptors and pentraxins in solution and on cell surfaces are similar to antibody binding to low affinity Fc receptors. Crystallographic and mutagenesis studies have defined the structural features of these interactions and determined the stoichiometry of binding as one-to-one. Pentraxin aggregation or binding to multivalent ligands increases the avidity of binding and results in activation of these receptors for phagocytosis and cytokine synthesis. This review will discuss the structural and functional characteristics of pentraxin Fc receptor interactions and their implications for host defense and inflammation.
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Affiliation(s)
- Jinghua Lu
- Structural Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States
| | - Carolyn Mold
- Department of Molecular Genetics and Microbiology, Albuquerque, NM, United States.,Department of Internal Medicine, University of New Mexico, Albuquerque, NM, United States
| | | | - Peter D Sun
- Structural Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States
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12
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Morgan SB, Holzer B, Hemmink JD, Salguero FJ, Schwartz JC, Agatic G, Cameroni E, Guarino B, Porter E, Rijal P, Townsend A, Charleston B, Corti D, Tchilian E. Therapeutic Administration of Broadly Neutralizing FI6 Antibody Reveals Lack of Interaction Between Human IgG1 and Pig Fc Receptors. Front Immunol 2018; 9:865. [PMID: 29740451 PMCID: PMC5928291 DOI: 10.3389/fimmu.2018.00865] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 04/09/2018] [Indexed: 12/30/2022] Open
Abstract
Influenza virus infection is a significant global health threat. Because of the lack of cross-protective universal vaccines, short time window during which antivirals are effective and drug resistance, new therapeutic anti-influenza strategies are required. Broadly, cross-protective antibodies that target conserved sites in the hemagglutinin (HA) stem region have been proposed as therapeutic agents. FI6 is the first proven such monoclonal antibody to bind to H1-H16 and is protective in mice and ferrets. Multiple studies have shown that Fc-dependent mechanisms are essential for FI6 in vivo efficacy. Here, we show that therapeutic administration of FI6 either intravenously or by aerosol to pigs did not reduce viral load in nasal swabs or broncho-alveolar lavage, but aerosol delivery of FI6 reduced gross pathology significantly. We demonstrate that pig Fc receptors do not bind human IgG1 and that FI6 did not mediate antibody-dependent cytotoxicity (ADCC) with pig PBMC, confirming that ADCC is an important mechanism of protection by anti-stem antibodies in vivo. Enhanced respiratory disease, which has been associated with pigs with cross-reactive non-neutralizing anti-HA antibodies, did not occur after FI6 administration. Our results also show that in vitro neutralizing antibody responses are not a robust correlate of protection for the control of influenza infection and pathology in a natural host model.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Emily Porter
- School of Veterinary Sciences, University of Bristol, Langford, United Kingdom
| | - Pramila Rijal
- Weatherall Institute for Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Alain Townsend
- Weatherall Institute for Molecular Medicine, University of Oxford, Oxford, United Kingdom
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13
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Asymmetric Fc Engineering for Bispecific Antibodies with Reduced Effector Function. Antibodies (Basel) 2017; 6:antib6020007. [PMID: 31548523 PMCID: PMC6698841 DOI: 10.3390/antib6020007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 03/10/2017] [Accepted: 04/25/2017] [Indexed: 11/17/2022] Open
Abstract
Asymmetric bispecific antibodies are a rapidly expanding therapeutic antibody class, designed to recognize two different target epitopes concurrently to achieve novel functions not available with normal antibodies. Many therapeutic designs require antibodies with reduced or silenced effector function. Although many solutions have been described in the literature to knockout effector function, to date all of them have involved the use of a specific antibody subtype (e.g., IgG2 or IgG4), or symmetric mutations in the lower hinge or CH2 domain of traditional homodimeric monospecific antibodies. In the context of a heterodimeric Fc, we describe novel asymmetric Fc mutations with reduced or silenced effector function in this article. These heteromultimeric designs contain asymmetric charged mutations in the lower hinge and the CH2 domain of the Fc. Surface plasmon resonance showed that the designed mutations display much reduced binding to all of the Fc gamma receptors and C1q. Ex vivo ADCC and CDC assays showed a consistent reduction in activity. Differential scanning calorimetry showed increased thermal stability for some of the designs. Finally, the asymmetric nature of the introduced charged mutations allowed for separation of homodimeric impurities by ion exchange chromatography, providing, as an added benefit, a purification strategy for the production of bispecific antibodies with reduced or silenced effector function.
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14
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Schlothauer T, Herter S, Koller CF, Grau-Richards S, Steinhart V, Spick C, Kubbies M, Klein C, Umaña P, Mössner E. Novel human IgG1 and IgG4 Fc-engineered antibodies with completely abolished immune effector functions. Protein Eng Des Sel 2016; 29:457-466. [PMID: 27578889 DOI: 10.1093/protein/gzw040] [Citation(s) in RCA: 207] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 07/19/2016] [Indexed: 02/06/2023] Open
Abstract
Recombinant human IgG antibodies (hIgGs) completely devoid of binding to Fcγ receptors (FcγRs) and complement protein C1q, and thus with abolished immune effector functions, are of use for various therapeutic applications in order to reduce FcγR activation and Fc-mediated toxicity. Fc engineering approaches described to date only partially achieve this goal or employ a large number of mutations, which may increase the risk of anti-drug antibody generation. We describe here two new, engineered hIgG Fc domains, hIgG1-P329G LALA and hIgG4-P329G SPLE, with completely abolished FcγR and C1q interactions, containing a limited number of mutations and with unaffected FcRn interactions and Fc stability. Both 'effector-silent' Fc variants are based on a novel Fc mutation, P329G that disrupts the formation of a proline sandwich motif with the FcγRs. As this motif is present in the interface of all IgG Fc/FcγR complexes, its disruption can be applied to all human and most of the other mammalian IgG subclasses in order to create effector silent IgG molecules.
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Affiliation(s)
- Tilman Schlothauer
- Department of Protein Analytics, Roche Pharmaceutical Research and Early Development, Large Molecules Research, Roche Innovation Center Penzberg, Nonnenwald 2, D-82377 Penzberg, Germany
| | - Sylvia Herter
- Roche Pharmaceutical Research and Early Development, Large Molecules Research, Roche Innovation Center Zurich, Wagistrasse 18, CH-8952 Schlieren, Switzerland
| | - Claudia Ferrara Koller
- Roche Pharmaceutical Research and Early Development, Large Molecules Research, Roche Innovation Center Zurich, Wagistrasse 18, CH-8952 Schlieren, Switzerland
| | - Sandra Grau-Richards
- Roche Pharmaceutical Research and Early Development, Large Molecules Research, Roche Innovation Center Zurich, Wagistrasse 18, CH-8952 Schlieren, Switzerland
| | - Virginie Steinhart
- Roche Pharmaceutical Research and Early Development, Large Molecules Research, Roche Innovation Center Zurich, Wagistrasse 18, CH-8952 Schlieren, Switzerland
| | - Christian Spick
- Department of Protein Analytics, Roche Pharmaceutical Research and Early Development, Large Molecules Research, Roche Innovation Center Penzberg, Nonnenwald 2, D-82377 Penzberg, Germany
| | - Manfred Kubbies
- Department of Protein Analytics, Roche Pharmaceutical Research and Early Development, Large Molecules Research, Roche Innovation Center Penzberg, Nonnenwald 2, D-82377 Penzberg, Germany
| | - Christian Klein
- Roche Pharmaceutical Research and Early Development, Large Molecules Research, Roche Innovation Center Zurich, Wagistrasse 18, CH-8952 Schlieren, Switzerland
| | - Pablo Umaña
- Roche Pharmaceutical Research and Early Development, Large Molecules Research, Roche Innovation Center Zurich, Wagistrasse 18, CH-8952 Schlieren, Switzerland
| | - Ekkehard Mössner
- Roche Pharmaceutical Research and Early Development, Large Molecules Research, Roche Innovation Center Zurich, Wagistrasse 18, CH-8952 Schlieren, Switzerland
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15
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Abou-Alfa GK, Puig O, Daniele B, Kudo M, Merle P, Park JW, Ross P, Peron JM, Ebert O, Chan S, Poon TP, Colombo M, Okusaka T, Ryoo BY, Minguez B, Tanaka T, Ohtomo T, Ukrainskyj S, Boisserie F, Rutman O, Chen YC, Xu C, Shochat E, Jukofsky L, Reis B, Chen G, Di Laurenzio L, Lee R, Yen CJ. Randomized phase II placebo controlled study of codrituzumab in previously treated patients with advanced hepatocellular carcinoma. J Hepatol 2016; 65:289-95. [PMID: 27085251 DOI: 10.1016/j.jhep.2016.04.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Revised: 03/30/2016] [Accepted: 04/05/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND & AIMS Codrituzumab, a humanized monoclonal antibody against Glypican-3 (GPC3) that is expressed in hepatocellular carcinoma (HCC), interacts with CD16/FcγRIIIa and triggers antibody-dependent cytotoxicity. Codrituzumab was studied vs. placebo in a randomized phase II trial in advanced HCC patients who had failed prior systemic therapy. METHODS Patients with advanced HCC who had failed prior systemic therapy, ⩾18years, Eastern cooperative oncology group (ECOG) 0-1, Child-Pugh A were randomized 2:1 to biweekly codrituzumab 1600mg vs. placebo. Patients were stratified based on GPC3 immunohistochemical expression: 2+/3+, 1+, and 0. Primary endpoint was progression free survival. Secondary endpoints include overall survival (OS), tolerability, pharmacokinetics, and an exploratory endpoint in biomarkers analysis. RESULTS 185 patients were enrolled: 125 received codrituzumab and 60 placebo: Median age 64/63, 85/75% male, 46/42% Asian, ECOG 0 65/63%, 74/77% having vascular invasion and/or extra-hepatic metastasis. 84%/70% had prior sorafenib. Drug exposure was 98.4% of planned dose, with an identical adverse events profile between the 2 groups. The median progression free survival and overall survival in the codrituzumab vs. placebo groups in months were: 2.6 vs. 1.5 (hazard ratios 0.97, p=0.87), and 8.7 vs. 10 (hazard ratios 0.96, p=0.82). Projected Ctrough at cycle 3day 1 based exposure, high CD16/FcγRIIIa on peripheral immune cells, and GPC3 expression in the tumor, were all associated with prolonged progression free survival and overall survival. CONCLUSIONS Codrituzumab did not show clinical benefit in this previously treated HCC population. Whether higher codrituzumab drug exposure or the use of CD16 and GPC3 as potential biomarkers would improve outcome remain unanswered questions. LAY SUMMARY Codrituzumab is a manufactured antibody against a liver cancer protein called glypican-3. In this clinical trial, codrituzumab was not found be effective against liver cancer. It was suggested though that a higher dose of codrituzumab or selecting patients with high level of glypican-3 or its mediator CD16 might improve outcome. CLINICAL TRIAL REGISTRATION This trial is registered at Clinicaltrials.gov (NCT01507168).
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Affiliation(s)
- Ghassan K Abou-Alfa
- Memorial Sloan Kettering Cancer Center, New York, NY, USA; Weill Cornell Medical College, New York, NY, USA.
| | - Oscar Puig
- Roche Innovation Center New York, Hoffmann-La Roche Inc., USA
| | | | | | - Philippe Merle
- Hopital de la Croix-Rousse, Hepatologie et Gastroenterologie, Lyon, France
| | | | - Paul Ross
- King's College Hospital, United Kingdom
| | | | - Oliver Ebert
- II. Medizinische Klinik und Poliklinik, Klinikum rechts der Isar, Technische Universität München, Germany
| | | | | | | | | | | | - Beatriz Minguez
- Liver Unit, Hospital Universitario Vall d́Hebron, Barcelona, Spain
| | | | | | | | | | - Olga Rutman
- Roche Innovation Center New York, Hoffmann-La Roche Inc., USA
| | - Ya-Chi Chen
- Roche Innovation Center New York, Hoffmann-La Roche Inc., USA
| | - Chao Xu
- Roche Innovation Center New York, Hoffmann-La Roche Inc., USA
| | - Eliezer Shochat
- Roche Innovation Center Basel, Hoffmann-La Roche, Switzerland
| | - Lori Jukofsky
- Roche Innovation Center New York, Hoffmann-La Roche Inc., USA
| | - Bernhard Reis
- Roche Innovation Center Basel, Hoffmann-La Roche, Switzerland
| | - Gong Chen
- Roche Innovation Center New York, Hoffmann-La Roche Inc., USA
| | | | - Ray Lee
- Roche Innovation Center New York, Hoffmann-La Roche Inc., USA
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16
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Abstract
Background Immunity to human influenza A virus (IAV) infection is only partially understood. Broadly non-neutralizing antibodies may assist in reducing disease but have not been well characterized. Methods We measured internalization of opsonized, influenza protein-coated fluorescent beads and live IAV into a monocytic cell line to study antibody-dependent phagocytosis (ADP) against multiple influenza hemagglutinin (HA) subtypes. We analyzed influenza HA-specific ADP in healthy human donors, in preparations of intravenous immunoglobulin (IVIG), and following IAV infection of humans and macaques. Results We found that both sera from healthy adults and IVIG preparations had broad ADP to multiple seasonal HA proteins and weak cross-reactive ADP to non-circulating HA proteins. The ADP in experimentally influenza-infected macaque plasma and naturally influenza-infected human sera mediated phagocytosis of both homologous and heterologous IAVs. Further, the IAV phagocytosed in an antibody-mediated manner had reduced infectivity in vitro. Conclusion We conclude that IAV infections in humans and macaques leads to the development of influenza-specific ADP that can clear IAV infection in vitro. Repeated exposure of humans to multiple IAV infections likely leads to the development of ADP that is cross-reactive to strains not previously encountered. Further analyses of the protective capacity of broadly reactive influenza-specific ADP is warranted.
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17
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Rayner LE, Hui GK, Gor J, Heenan RK, Dalby PA, Perkins SJ. The solution structures of two human IgG1 antibodies show conformational stability and accommodate their C1q and FcγR ligands. J Biol Chem 2015; 290:8420-38. [PMID: 25659433 PMCID: PMC4375494 DOI: 10.1074/jbc.m114.631002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 01/28/2015] [Indexed: 11/06/2022] Open
Abstract
The human IgG1 antibody subclass shows distinct properties compared with the IgG2, IgG3, and IgG4 subclasses and is the most exploited subclass in therapeutic antibodies. It is the most abundant subclass, has a half-life as long as that of IgG2 and IgG4, binds the FcγR receptor, and activates complement. There is limited structural information on full-length human IgG1 because of the challenges of crystallization. To rectify this, we have studied the solution structures of two human IgG1 6a and 19a monoclonal antibodies in different buffers at different temperatures. Analytical ultracentrifugation showed that both antibodies were predominantly monomeric, with sedimentation coefficients s20,w (0) of 6.3-6.4 S. Only a minor dimer peak was observed, and the amount was not dependent on buffer conditions. Solution scattering showed that the x-ray radius of gyration Rg increased with salt concentration, whereas the neutron Rg values remained unchanged with temperature. The x-ray and neutron distance distribution curves P(r) revealed two peaks, M1 and M2, whose positions were unchanged in different buffers to indicate conformational stability. Constrained atomistic scattering modeling revealed predominantly asymmetric solution structures for both antibodies with extended hinge structures. Both structures were similar to the only known crystal structure of full-length human IgG1. The Fab conformations in both structures were suitably positioned to permit the Fc region to bind readily to its FcγR and C1q ligands without steric clashes, unlike human IgG4. Our molecular models for human IgG1 explain its immune activities, and we discuss its stability and function for therapeutic applications.
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Affiliation(s)
- Lucy E Rayner
- From the Department of Structural and Molecular Biology, Division of Biosciences, Darwin Building, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Gar Kay Hui
- From the Department of Structural and Molecular Biology, Division of Biosciences, Darwin Building, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Jayesh Gor
- From the Department of Structural and Molecular Biology, Division of Biosciences, Darwin Building, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Richard K Heenan
- the ISIS Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, United Kingdom, and
| | - Paul A Dalby
- the Department of Biochemical Engineering, Division of Engineering, Roberts Building, University College London, Gower Street, London WC1E 7JE, United Kingdom
| | - Stephen J Perkins
- From the Department of Structural and Molecular Biology, Division of Biosciences, Darwin Building, University College London, Gower Street, London WC1E 6BT, United Kingdom,
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18
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Jegaskanda S, Reading PC, Kent SJ. Influenza-specific antibody-dependent cellular cytotoxicity: toward a universal influenza vaccine. THE JOURNAL OF IMMUNOLOGY 2014; 193:469-75. [PMID: 24994909 DOI: 10.4049/jimmunol.1400432] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
There is an urgent need for universal influenza vaccines that can control emerging pandemic influenza virus threats without the need to generate new vaccines for each strain. Neutralizing Abs to the influenza virus hemagglutinin glycoprotein are effective at controlling influenza infection but generally target highly variable regions. Abs that can mediate other functions, such as killing influenza-infected cells and activating innate immune responses (termed "Ab-dependent cellular cytotoxicity [ADCC]-mediating Abs"), may assist in protective immunity to influenza. ADCC-mediating Abs can target more conserved regions of influenza virus proteins and recognize a broader array of influenza strains. We review recent research on influenza-specific ADCC Abs and their potential role in improved influenza-vaccination strategies.
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Affiliation(s)
- Sinthujan Jegaskanda
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, Victoria 3010, Australia; and
| | - Patrick C Reading
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, Victoria 3010, Australia; and World Health Organization Collaborating Centre for Reference and Research on Influenza, Victorian Infectious Diseases Reference Laboratory, North Melbourne, Victoria 3051, Australia
| | - Stephen J Kent
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Parkville, Victoria 3010, Australia; and
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19
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Rayner LE, Hui GK, Gor J, Heenan RK, Dalby PA, Perkins SJ. The Fab conformations in the solution structure of human immunoglobulin G4 (IgG4) restrict access to its Fc region: implications for functional activity. J Biol Chem 2014; 289:20740-56. [PMID: 24876381 PMCID: PMC4110284 DOI: 10.1074/jbc.m114.572404] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 05/12/2014] [Indexed: 12/24/2022] Open
Abstract
Human IgG4 antibody shows therapeutically useful properties compared with the IgG1, IgG2, and IgG3 subclasses. Thus IgG4 does not activate complement and shows conformational variability. These properties are attributable to its hinge region, which is the shortest of the four IgG subclasses. Using high throughput scattering methods, we studied the solution structure of wild-type IgG4(Ser(222)) and a hinge mutant IgG4(Pro(222)) in different buffers and temperatures where the proline substitution suppresses the formation of half-antibody. Analytical ultracentrifugation showed that both IgG4 forms were principally monomeric with sedimentation coefficients s20,w(0) of 6.6-6.8 S. A monomer-dimer equilibrium was observed in heavy water buffer at low temperature. Scattering showed that the x-ray radius of gyration Rg was unchanged with concentration in 50-250 mm NaCl buffers, whereas the neutron Rg values showed a concentration-dependent increase as the temperature decreased in heavy water buffers. The distance distribution curves (P(r)) revealed two peaks, M1 and M2, that shifted below 2 mg/ml to indicate concentration-dependent IgG4 structures in addition to IgG4 dimer formation at high concentration in heavy water. Constrained x-ray and neutron scattering modeling revealed asymmetric solution structures for IgG4(Ser(222)) with extended hinge structures. The IgG4(Pro(222)) structure was similar. Both IgG4 structures showed that their Fab regions were positioned close enough to the Fc region to restrict C1q binding. Our new molecular models for IgG4 explain its inability to activate complement and clarify aspects of its stability and function for therapeutic applications.
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Affiliation(s)
- Lucy E Rayner
- From the Department of Structural and Molecular Biology, Division of Biosciences, Darwin Building and
| | - Gar Kay Hui
- From the Department of Structural and Molecular Biology, Division of Biosciences, Darwin Building and
| | - Jayesh Gor
- From the Department of Structural and Molecular Biology, Division of Biosciences, Darwin Building and
| | - Richard K Heenan
- ISIS Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, United Kingdom
| | - Paul A Dalby
- Department of Biochemical Engineering, Division of Engineering, Roberts Building, University College London, Gower Street, London WC1E 6BT, United Kingdom and
| | - Stephen J Perkins
- From the Department of Structural and Molecular Biology, Division of Biosciences, Darwin Building and
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The binding of soluble recombinant human Fcγ receptor I for human immunoglobulin G is conferred by its first and second extracellular domains. Mol Immunol 2013; 54:403-7. [PMID: 23399386 DOI: 10.1016/j.molimm.2013.01.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 01/11/2013] [Accepted: 01/11/2013] [Indexed: 11/22/2022]
Abstract
Human FcγRI is a high affinity receptor for the Fc portion of human immunoglobulin G (IgG), and has extracellular, transmembrane and cytoplasmic regions. The extracellular region of human FcγRI, which is the part that interacts with human IgG, is comprised of three immunoglobulin-like domains. Unlike low affinity Fcγ receptors (FcγRII and FcγRIII), FcγRI has a unique third extracellular domain (D3). This study investigated the contribution of D3 to the binding between recombinant human FcγRI (rhFcγRI) and human IgG. The three extracellular domains and the first and second extracellular domains of human FcγRI were expressed by Escherichia coli as rhFcγRI and rhFcγRI-D1D2, respectively. The binding specificity of rhFcγRI-D1D2 to human IgG subclasses was the same as that of rhFcγRI. From surface plasmon resonance analysis, the binding affinity of rhFcγRI-D1D2 for human IgG1/κ was high (the equilibrium dissociation constant: KD=8.04 × 10(-10)M), but slightly lower than that of rhFcγRI (KD=2.59 × 10(-10)M). While the association of rhFcγRI-D1D2 with human IgG1/κ was same as that of rhFcγRI, the dissociation of rhFcγRI-D1D2 was faster than that of rhFcγRI. From these results, D3 of rhFcγRI would not contribute directly to the binding specificity and association of rhFcγRI, but to the holding bound human IgG.
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21
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Rayner LE, Kadkhodayi-Kholghi N, Heenan RK, Gor J, Dalby PA, Perkins SJ. The solution structure of rabbit IgG accounts for its interactions with the Fc receptor and complement C1q and its conformational stability. J Mol Biol 2012. [PMID: 23178865 DOI: 10.1016/j.jmb.2012.11.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Solution structures for antibodies are critical to understand function and therapeutic applications. The stability of the solution structure of rabbit IgG in different buffers and temperatures was determined by analytical ultracentrifugation and X-ray and neutron scattering. Rabbit IgG showed a principally monomeric species, which is well resolved from small amounts of a dimeric species. The proportion of dimer increased with increased concentration, decreased temperature and heavy water from 8% to 25% in all buffers except for high salt (250 mM NaCl). The Guinier X-ray radius of gyration R(G) likewise increased with concentration in 137 mM NaCl buffer but was unchanged in 250 mM NaCl buffer. The Guinier neutron R(G) values increased as the temperature decreased. The X-ray and neutron distance distribution curves P(r) revealed two peaks, M1 and M2, whose positions did not change with concentration to indicate unchanged structures under all these conditions. The maximum dimension increased with concentration because of dimer formation. Constrained scattering modeling reproducibly revealed very similar asymmetric solution structures for monomeric rabbit IgG in different buffers, in which the Fab-Fc and Fab-Fab pairs were separated by maximally extended hinge structures. The dimer was best modeled by two pairs of Fab regions forming tip-to-tip contacts. The intact rabbit IgG structures explained the ability of its two ligands, the Fc receptor and complement C1q, to bind to the top of its Fc region that is fully accessible and unhindered by the Fab regions.
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Affiliation(s)
- Lucy E Rayner
- Department of Structural and Molecular Biology, Division of Biosciences, Darwin Building, University College London, Gower Street, London WC1E 6BT, UK
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22
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Abstract
Pentraxins are innate pattern recognition molecules whose major function is to bind microbial pathogens or cellular debris during infection and inflammation and, by doing so, contribute to the clearance of necrotic cells as well as pathogens through complement activations. Fc receptors are the cellular mediators of antibody functions. Although conceptually separated, both pentraxins and antibodies are important factors in controlling acute and chronic inflammation and infections. In recent years, increasing experimental evidence suggests a direct link between the innate pentraxins and humoral Fc receptors. Specifically, both human and mouse pentraxins recognize major forms of Fc receptors in solution and on cell surfaces with affinities similar to antibodies binding to their low affinity Fc receptors. Like immune complex, pentraxin aggregation and opsonization of pathogen result in Fc receptor and macrophage activation. The recently published crystal structure of human serum amyloid P (SAP) in complex with FcγRIIA further illustrated similarities to antibody recognition. These recent findings implicate a much broader role than complement activation for pentraxins in immunity. This review summarizes the structural and functional work that bridge the innate pentraxins and the adaptive Fc receptor functions. In many ways, pentraxins can be regarded as innate antibodies.
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Affiliation(s)
- Jinghua Lu
- Structural Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Kristopher D. Marjon
- Department of Internal Medicine and Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM, USA
| | - Carolyn Mold
- Department of Internal Medicine and Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM, USA
| | - Terry W. Du Clos
- Department of Internal Medicine and Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM, USA
- VA Medical Center, Albuquerque, NM, USA
| | - Peter D. Sun
- Structural Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
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23
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Lu J, Ellsworth JL, Hamacher N, Oak SW, Sun PD. Crystal structure of Fcγ receptor I and its implication in high affinity γ-immunoglobulin binding. J Biol Chem 2011; 286:40608-13. [PMID: 21965667 DOI: 10.1074/jbc.m111.257550] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Fcγ receptors (FcγRs) play critical roles in humoral and cellular immune responses through interactions with the Fc region of immunoglobulin G (IgG). Among them, FcγRI is the only high affinity receptor for IgG and thus is a potential target for immunotherapy. Here we report the first crystal structure of an FcγRI with all three extracellular Ig-like domains (designated as D1, D2, and D3). The structure shows that, first, FcγRI has an acute D1-D2 hinge angle similar to that of FcεRI but much smaller than those observed in the low affinity Fcγ receptors. Second, the D3 domain of FcγRI is positioned away from the putative IgG binding site on the receptor and is thus unlikely to make direct contacts with Fc. Third, the replacement of FcγRIII FG-loop ((171)LVGSKNV(177)) with that of FcγRI ((171)MGKHRY(176)) resulted in a 15-fold increase in IgG(1) binding affinity, whereas a valine insertion in the FcγRI FG-loop ((171)MVGKHRY(177)) abolished the affinity enhancement. Thus, the FcγRI FG-loop with its conserved one-residue deletion is critical to the high affinity IgG binding. The structural results support FcγRI binding to IgG in a similar mode as its low affinity counterparts. Taken together, our study suggests a molecular mechanism for the high affinity IgG recognition by FcγRI and provides a structural basis for understanding its physiological function and its therapeutic implication in treating autoimmune diseases.
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Affiliation(s)
- Jinghua Lu
- Structural Immunology Section, Laboratory of Immunogenetics, NIAID, National Institutes of Health, Rockville, Maryland, USA
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24
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Bonetto S, Spadola L, Buchanan AG, Jermutus L, Lund J. Identification of cyclic peptides able to mimic the functional epitope of IgG1-Fc for human Fc gammaRI. FASEB J 2008; 23:575-85. [PMID: 18957574 PMCID: PMC2633172 DOI: 10.1096/fj.08-117069] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Identification of short, structured peptides able to mimic potently protein-protein interfaces remains a challenge in drug discovery. We report here the use of a naive cyclic peptide phage display library to identify peptide ligands able to recognize and mimic IgG1-Fc functions with FcγRI. Selection by competing off binders to FcγRI with IgG1 allowed the isolation of a family of peptides sharing the common consensus sequence TX2CXXθPXLLGCΦXE (θ represents a hydrophobic residue, Φ is usually an acidic residue, and X is any residue) and able to inhibit IgG1 binding to FcγRI. In soluble form, these peptides antagonize superoxide generation mediated by IgG1. In complexed form, they trigger phagocytosis and a superoxide burst. Unlike IgG, these peptides are strictly FcγRI-specific among the FcγRs. Molecular modeling studies suggest that these peptides can adopt 2 distinct and complementary conformers, each able to mimic the discontinuous interface contacts constituted by the Cγ2-A and -B chains of Fc for FcγRI. In addition, by covalent homodimerization, we engineered a synthetic bivalent 37-mer peptide that retains the ability to trigger effector functions. We demonstrate here that it is feasible to maintain IgG-Fc function within a small structured peptide. These peptides represent a new format for modulation of effector functions.—Bonetto, S., Spadola, L., Buchanan, A. G., Jermutus, L. Lund, J. Identification of cyclic peptides able to mimic the functional epitope of IgG1-Fc for human FcγRI.
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Affiliation(s)
- Stephane Bonetto
- MedImmune, Research, Granta Park, Milstein Bldg., Cambridge, CB21 6GH, UK
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25
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Abstract
Discovery of a large family of Fc receptor-like (FCRL) molecules, homologous to the well-known receptors for the Fc portion of immunoglobulin (FCR), has uncovered an impressive abundance of immunoglobulin superfamily (IgSF) genes in the human 1q21-23 chromosomal region and revealed significant diversity for these genes between humans and mice. The observation that FCRL representatives are members of an ancient multigene family that share a common ancestor with the classical FCR is underscored by their linked genomic locations, gene structure, shared extracellular domain composition, and utilization of common cytoplasmic tyrosine-based signaling elements. In contrast to the conventional FCR, however, FCRL molecules possess diverse extracellular frameworks, autonomous or dual signaling properties, and preferential B lineage expression. Most importantly, there is no strong evidence thus far to support a role for them as Ig-binding receptors. These characteristics, in addition to their identification in malignancies and autoimmune disorders, predict a fundamental role for these receptors as immunomodulatory agents in normal and subverted B lineage cells.
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Affiliation(s)
- Randall S Davis
- Division of Developmental and Clinical Immunology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294-3300, USA.
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26
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Rogers KA, Scinicariello F, Attanasio R. IgG Fc receptor III homologues in nonhuman primate species: genetic characterization and ligand interactions. THE JOURNAL OF IMMUNOLOGY 2006; 177:3848-56. [PMID: 16951347 DOI: 10.4049/jimmunol.177.6.3848] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Ig Fc receptors bind to immune complexes through interactions with the Fc regions of specific Ab subclasses to initiate or inhibit the defense mechanisms of the leukocytes on which they are expressed. The mechanism of action of IgG-based therapeutic molecules, which are routinely evaluated in nonhuman primate models, involves binding to the low-affinity FcRIII (CD16). The premise that IgG/CD16 interactions in nonhuman primates mimic those present in humans has not been evaluated. Therefore, we have identified and characterized CD16 and associated TCR zeta-chain homologues in rhesus macaques, cynomolgus macaques, baboons, and sooty mangabeys. Similar to humans, CD16 expression was detected on a lymphocyte subpopulation, on monocytes, and on neutrophils of sooty mangabeys. However, CD16 was detected only on a lymphocyte subpopulation and on monocytes in macaques and baboons. A nonhuman primate rCD16 generated in HeLa cells interacted with human IgG1 and IgG2. By contrast, human CD16 binds to IgG1 and IgG3. As shown for humans, the mAb 3G8 was able to block IgG binding to nonhuman primate CD16 and inhibition of nonhuman primate CD16 N-glycosylation enhanced IgG binding. Clearly, differences in interaction with IgG subclasses and in cell-type expression should be considered when using these models for in vivo evaluation of therapeutic Abs.
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Affiliation(s)
- Kenneth A Rogers
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
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27
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Davis RS, Ehrhardt GRA, Leu CM, Hirano M, Cooper MD. An extended family of Fc receptor relatives. Eur J Immunol 2005; 35:674-80. [PMID: 15688344 DOI: 10.1002/eji.200425886] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A surprising number of Fc receptor (FcR) relatives have been recognized recently with the potential capacity to modulate innate and adaptive immune responses. The six human FcR homologs (FcRH1-6), which belong to a phylogenetically conserved gene family, have variable numbers of extracellular immunoglobulin domains of five different subtypes. FcRH immunoregulatory potential is implicated by the presence of consensus tyrosine-based activation or inhibition motifs in their cytoplasmic tails. All but one of these new receptors, FcRH6, are expressed on B cells at different stages in differentiation. Their ligands, function, and prospective roles as diagnostic B cell markers and therapeutic targets are topics of intense interest.
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Affiliation(s)
- Randall S Davis
- Division of Developmental and Clinical Immunology, University of Alabama, Birmingham, USA
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28
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Abstract
The function of natural-killer (NK) cells is modulated by the balance between a number of activating and inhibitory receptors. Killer immunoglobulinlike receptors (KIRs) are mostly inhibitory receptors. They play a critical role in recognizing self-class-I major histocompatibility complex (MHC) molecules and thus protect healthy host cells from NK-targeted lysis. In contrast, both NKG2D and CD16 are activating NK receptors that trigger the NK-cell lysis of various tumor and virally infected cells through either direct ligand engagement or antibody-dependent cellular cytotoxicity (ADCC). Through structural studies of members of these distinct receptor families, in particular, the structure and recognition between KIR2DL2 and HLA-Cw3, that between NKG2D and ULBP3, and that between CD16 and IgG Fc, considerable understandings have been achieved about their function and their ligand recognition.
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Affiliation(s)
- Peter D Sun
- Structural Immunology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
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29
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Affiliation(s)
- Roald Nezlin
- Department of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
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30
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Davis RS, Dennis G, Odom MR, Gibson AW, Kimberly RP, Burrows PD, Cooper MD. Fc receptor homologs: newest members of a remarkably diverse Fc receptor gene family. Immunol Rev 2002; 190:123-36. [PMID: 12493010 DOI: 10.1034/j.1600-065x.2002.19009.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Newfound relatives of the classical Fc receptors (FcR) have been provisionally named the Fc receptor homologs (FcRH). The recent identification of eight human and six mouse FcRH genes substantially increases the size and functional potential of the FcR family. The extended family of FcR and FcRH genes spans approximately 15 Mb of the human chromosome 1q21-23 region, whereas in mice this family is split between chromosomes 1 and 3. The FcRH genes encode molecules with variable combinations of five subtypes of immunoglobulin (Ig) domains. The presence of a conserved sequence motif in one Ig domain subtype implies Ig Fc binding capability for many FcRH family members that are preferentially expressed by B lineage cells. In addition, most FcRH family members have consensus tyrosine-based activating and inhibitory motifs in their cytoplasmic domains, while the others lack features typical of transmembrane receptors. The FcRH family members, like the classical FcRs, come in multiple isoforms and allelic variations. The unique individual and polymorphic properties of the FcR/FcRH members indicate a remarkably diverse Fc receptor gene family with immunoregulatory function.
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Affiliation(s)
- Randall S Davis
- Division of Hematology/Oncology, University of Alabama at Birmingham, AL 35294, USA
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31
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Davis RS, Dennis G, Kubagawa H, Cooper MD. Fc receptor homologs (FcRH1-5) extend the Fc receptor family. Curr Top Microbiol Immunol 2002; 266:85-112. [PMID: 12014205 DOI: 10.1007/978-3-662-04700-2_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- R S Davis
- Division of Hematology/Oncology, Department of Medicine, University of Alabama at Birmingham, AL 35294-3300, USA
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32
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Abstract
Fc receptors mediate antibody dependent inflammatory response and cytotoxicity as well as certain autoimmune dysfunctions. Fcgamma receptors interact with IgG antibodies by binding the Fc portion of the antibody in asymmetric fashion creating a 1:1 receptor-ligand stoichiometry. Regions of the C-terminal domain of Fc receptors including the BC, C'E, FG loops, and the C' beta-strand interact with immunoglobulins. The lower hinge region of the antibody contributes most of the binding to the low affinity Fcgamma receptors. Carbohydrates attached to the conserved glycosylation site on Fc portion of an antibody are critical to the recognition of immunoglobulins by the low affinity Fcgamma receptor. They are likely to function as a substitution for the hydrophobic core to preserve an optimal lower hinge conformation for the receptor binding. Subtype specificities of FcgammaRIII receptor probably are determined by the length of the lower hinge regions of immunoglobulins, but not their amino acid composition as revealed by the binding study of the lower hinge peptides. These studies also paved a new way for designing of novel therapeutic compounds in fighting autoimmune diseases.
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Affiliation(s)
- Sergei Radaev
- Structural Biology Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12441 Parklawn Drive, Rockville, MD 20852, USA
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33
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Sondermann P, Kaiser J, Jacob U. Molecular basis for immune complex recognition: a comparison of Fc-receptor structures. J Mol Biol 2001; 309:737-49. [PMID: 11397093 DOI: 10.1006/jmbi.2001.4670] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Once antigen is opsonised by IgG it is removed from the circulation by Fcgamma-receptor expressing cells. Fcgamma-receptors are type I transmembrane molecules that carry extracellular parts consisting of two or three immunoglobulin domains. Previously solved structures of Fc-receptors reveal that the N-terminal two Ig-like domains are arranged in a steep angle forming a heart-shaped structure. The crystal structure of the FcgammaRIII/hIgG1-Fc-fragment demonstrated that the Fc-fragment is recognised through loops of the C-terminal receptor domain of the FcgammaRIII. As the overall structure of the FcRs and their Ig ligands are very similar we modelled the Ig complexes with FcgammaRI, FcgammaRII and FcepsilonRIalpha based on the FcgammaRIII/hIgG1-Fc-fragment structure. The obtained models are consistent with the observed biochemical data and may explain the observed specificity and affinities.
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Affiliation(s)
- P Sondermann
- Max-Planck-Institut für Biochemie, Abteilung Strukturforschung, Am Klopferspitz 18a, Martinsried, D-82152, Germany.
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34
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Sulica A, Morel P, Metes D, Herberman RB. Ig-binding receptors on human NK cells as effector and regulatory surface molecules. Int Rev Immunol 2001; 20:371-414. [PMID: 11878510 DOI: 10.3109/08830180109054414] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The receptors on human natural killer 9NK cells which can specifically bind the Fc portion of immunoglobulin molecules (Fc receptors) have been extensively studied. The best known and studied Fc receptor on human NK cells is FcgammaRIIIa. Interactions of NK cells with IgG antibodies via this receptor are well known to induce a signal transduction cascade and lead to antibody-dependent cell-mediated cytotoxicity (ADCC) as well as release of various cytokines. In addition, interactions with monomeric IgG and FcgammaRIIIa have been demonstrated, which result in negative regulation of NK activity and other immunomodulatory effects. Over the past several years, it has also become increasingly appreciated that human NK cells express a variety of other Fc receptors, including FcmuR, which also can mediate effector and immunoregulatory functions. Also, a novel form of FcgammaR has been demonstrated on human NK cells, termed FcgammaRIIc. Recent molecular studies have shown considerable polymorphism in the genes for FcgammaIIc and the functional consequences are being dissected. This appears to include cross-talk between FcgammaRIIIa and at least some forms of FcgammaRIIc, which may have important functional consequences.
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Affiliation(s)
- A Sulica
- Center for Immunology, Bucharest, Romania
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35
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Radaev S, Motyka S, Fridman WH, Sautes-Fridman C, Sun PD. The structure of a human type III Fcgamma receptor in complex with Fc. J Biol Chem 2001; 276:16469-77. [PMID: 11297532 DOI: 10.1074/jbc.m100350200] [Citation(s) in RCA: 269] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fcgamma receptors mediate antibody-dependent inflammatory responses and cytotoxicity as well as certain autoimmune dysfunctions. Here we report the crystal structure of a human Fc receptor (FcgammaRIIIB) in complex with an Fc fragment of human IgG1 determined from orthorhombic and hexagonal crystal forms at 3.0- and 3.5-A resolution, respectively. The refined structures from the two crystal forms are nearly identical with no significant discrepancies between the coordinates. Regions of the C-terminal domain of FcgammaRIII, including the BC, C'E, FG loops, and the C' beta-strand, bind asymmetrically to the lower hinge region, residues Leu(234)-Pro(238), of both Fc chains creating a 1:1 receptor-ligand stoichiometry. Minor conformational changes are observed in both the receptor and Fc upon complex formation. Hydrophobic residues, hydrogen bonds, and salt bridges are distributed throughout the receptor.Fc interface. Sequence comparisons of the receptor-ligand interface residues suggest a conserved binding mode common to all members of immunoglobulin-like Fc receptors. Structural comparison between FcgammaRIII.Fc and FcepsilonRI.Fc complexes highlights the differences in ligand recognition between the high and low affinity receptors. Although not in direct contact with the receptor, the carbohydrate attached to the conserved glycosylation residue Asn(297) on Fc may stabilize the conformation of the receptor-binding epitope on Fc. An antibody-FcgammaRIII model suggests two possible ligand-induced receptor aggregations.
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Affiliation(s)
- S Radaev
- Structural Biology Section, Laboratory of Immunogenetics, NIAID, National Institutes of Health, Rockville, Maryland 20852, USA
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36
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Radaev S, Sun PD. Recognition of IgG by Fcgamma receptor. The role of Fc glycosylation and the binding of peptide inhibitors. J Biol Chem 2001; 276:16478-83. [PMID: 11297533 DOI: 10.1074/jbc.m100351200] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recently determined crystal structures of the complex between immunoglobulin constant regions (Fc) and their Fc-respective receptors (FcR) have revealed the detailed molecular interactions of this receptor-ligand pair. Of particular interest is the contribution of a glycosylation at Asn(297) of the C(H)2 domain of IgG to receptor recognition. The carbohydrate moieties are found outside the receptor.Fc interface in all receptor.Fc complex structures. To understand the role of glycosylation in FcR recognition, the receptor affinities of a deglycosylated IgG1 and its Fc fragment were determined by solution binding studies using surface plasmon resonance. The removal of carbohydrates resulted in a non-detectable receptor binding to the Fc alone and a 15- to 20-fold reduction of the receptor binding to IgG1, suggesting that the carbohydrates are important in the function of the FcgammaRIII. Structurally, the carbohydrates attached to Asn(297) fill the cavity between the C(H)2 domains of Fc functioning equivalently as a hydrophobic core. This may stabilize a favorable lower hinge conformation for the receptor binding. The structure of the complex also revealed the dominance of the lower hinge region in receptor.Fc recognition. To evaluate the potential of designing small molecular ligands to inhibit the receptor function, four lower hinge peptides were investigated for their ability to bind to the receptor FcgammaRIII. These peptides bind specifically to FcgammaRIII with affinities 20- to 100-fold lower than IgG1 and are able to compete with Fc in receptor binding. The results of peptide binding illustrate new ways of designing therapeutic compounds to block Fc receptor activation.
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Affiliation(s)
- S Radaev
- Structural Biology Section, Laboratory of Immunogenetics, NIAID, National Institutes of Health, Rockville, Maryland 20852, USA
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37
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Sondermann P, Huber R, Oosthuizen V, Jacob U. The 3.2-A crystal structure of the human IgG1 Fc fragment-Fc gammaRIII complex. Nature 2000; 406:267-73. [PMID: 10917521 DOI: 10.1038/35018508] [Citation(s) in RCA: 546] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The immune response depends on the binding of opsonized antigens to cellular Fc receptors and the subsequent initiation of various cellular effector functions of the immune system. Here we describe the crystal structures of a soluble Fc gamma receptor (sFc gammaRIII, CD16), an Fc fragment from human IgG1 (hFc1) and their complex. In the 1:1 complex the receptor binds to the two halves of the Fc fragment in contact with residues of the C gamma2 domains and the hinge region. Upon complex formation the angle between the two sFc gammaRIII domains increases significantly and the Fc fragment opens asymmetrically. The high degree of amino acid conservation between sFc gammaRIII and other Fc receptors, and similarly between hFc1 and related immunoglobulins, suggest similar structures and modes of association. Thus the described structure is a model for immune complex recognition and helps to explain the vastly differing affinities of other Fc gammaR-IgG complexes and the Fc epsilonRI alpha-IgE complex.
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Affiliation(s)
- P Sondermann
- Max-Planck-Institut für Biochemie, Martinsried, Germany.
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Moldovan I, Galon J, Maridonneau-Parini I, Roman Roman S, Mathiot C, Fridman WH, Sautès-Fridman C. Regulation of production of soluble Fc gamma receptors type III in normal and pathological conditions. Immunol Lett 1999; 68:125-34. [PMID: 10397167 DOI: 10.1016/s0165-2478(99)00041-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
CD16 (Fc gamma R type III), a low affinity IgG Fc receptor, is found in two forms, a transmembrane Fc gamma RIIIa expressed by NK cells and monocytes and a phosphatidylinositol-linked Fc gamma RIIIb present on neutrophils. Exposure of neutrophils to inflammatory signals induces a rapid loss of CD16 expression and release of a soluble form of CD16 (sCD16). Soluble CD16 circulates in plasma, levels being reduced in sera from patients with multiple myeloma. In the present manuscript the authors summarize work that aimed to better understand: (i) the role of proteinases in sCD16 production and CD16 membrane shedding; and (ii) the regulation of sCD16 levels in multiple myeloma patients and the possible biological consequences of its decrease in this disease. Soluble CD16 was purified from human serum. Its N-terminal sequencing demonstrated that it originates from neutrophil CD16 and its C-terminal sequencing showed that the cleavage site was between Val 196 and Ser 197, close to the membrane anchor. Analysis of the effect of protease inhibitors revealed that the cleavage leading to sCD16 production by PMA-activated neutrophils was metalloproteinase-dependent. In addition, membrane and sCD16 were sensitive to serine proteinases released by azurophil granules or added under purified form. The reduction of sCD16 levels that occurs in patients with multiple myeloma was associated with a slight decrease in circulating neutrophils, but not with a significant defect in sCD16 production by neutrophils, as detected in vitro. Moreover, addition of a recombinant sCD16 to plasmocytoma lines did not significantly modify their proliferation and Ig secretion.
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Affiliation(s)
- I Moldovan
- INSERM U255, Institut Curie, Paris, France
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FcγRIII (CD16)-Deficient Mice Show IgG Isotype-Dependent Protection to Experimental Autoimmune Hemolytic Anemia. Blood 1998. [DOI: 10.1182/blood.v92.11.3997] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
In autoimmune hemolytic anemia (AIHA), there is accumulating evidence for an involvement of FcγR expressed by phagocytic effector cells, but demonstration of a causal relationship between individual FcγRs and IgG isotypes for disease development is lacking. Although the relevance of IgG isotypes to human AIHA is limited, we could show a clear IgG isotype dependency in murine AIHA using pathogenic IgG1 (105-2H) and IgG2a (34-3C) autoreactive anti–red blood cell antibodies in mice defective for FcγRIII, and comparing the clinical outcome to those in wild-type mice. FcγRIII-deficient mice were completely resistent to the pathogenic effects of 105-2H monoclonal antibody, as shown by a lack of IgG1-mediated erythrophagocytosis in vitro and in vivo. In addition, the IgG2a response by 34-3C induced a less severe but persistent AIHA in FcγRIII knock-out mice, as documented by a decrease in hematocrit. Blocking studies indicated that the residual anemic phenotype induced by 34-3C in the absence of FcγRIII reflects an activation of FcγRI that is normally coexpressed with FcγRIII on macrophages. Together these results show that the pathogenesis of AIHA through IgG1-dependent erythrophagocytosis is exclusively mediated by FcγRIII and further suggest that FcγRI, in addition to FcγRIII, contributes to this autoimmune disease when other IgG isotypes such as IgG2a are involved.
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Abstract
In autoimmune hemolytic anemia (AIHA), there is accumulating evidence for an involvement of FcγR expressed by phagocytic effector cells, but demonstration of a causal relationship between individual FcγRs and IgG isotypes for disease development is lacking. Although the relevance of IgG isotypes to human AIHA is limited, we could show a clear IgG isotype dependency in murine AIHA using pathogenic IgG1 (105-2H) and IgG2a (34-3C) autoreactive anti–red blood cell antibodies in mice defective for FcγRIII, and comparing the clinical outcome to those in wild-type mice. FcγRIII-deficient mice were completely resistent to the pathogenic effects of 105-2H monoclonal antibody, as shown by a lack of IgG1-mediated erythrophagocytosis in vitro and in vivo. In addition, the IgG2a response by 34-3C induced a less severe but persistent AIHA in FcγRIII knock-out mice, as documented by a decrease in hematocrit. Blocking studies indicated that the residual anemic phenotype induced by 34-3C in the absence of FcγRIII reflects an activation of FcγRI that is normally coexpressed with FcγRIII on macrophages. Together these results show that the pathogenesis of AIHA through IgG1-dependent erythrophagocytosis is exclusively mediated by FcγRIII and further suggest that FcγRI, in addition to FcγRIII, contributes to this autoimmune disease when other IgG isotypes such as IgG2a are involved.
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Galon J, Moldovan I, Galinha A, Provost-Marloie MA, Kaudewitz H, Roman-Roman S, Fridman WH, Sautès C. Identification of the cleavage site involved in production of plasma soluble Fc gamma receptor type III (CD16). Eur J Immunol 1998; 28:2101-7. [PMID: 9692878 DOI: 10.1002/(sici)1521-4141(199807)28:07<2101::aid-immu2101>3.0.co;2-w] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
CD16 (FcgammaR type III) is a low-affinity IgG Fc receptor (R) that exists in two isoforms, a transmembrane FcgammaRIIIa expressed by NK cells and monocytes, and a phosphatidylinositol-linked FcgammaRIIIb expressed by neutrophils. A soluble form of CD16 (sCD16) circulates in plasma. The cleavage site and the nature of the enzyme(s) involved in production of sCD16 were investigated. Soluble CD16 was purified to apparent homogeneity from human serum by eight steps, including anion exchange and immunoaffinity chromatography. Serum sCD16 was sequenced at both ends, as well as a recombinant form of sCD16 used as control. N-terminal sequencing demonstrated that serum sCD16 originates from neutrophil FcgammaRIIIb and C-terminal sequencing suggested that the cleavage site is between Val 196 and Ser 197, close to the membrane anchor. Addition of a hydroxamate-based inhibitor of Zn2+ metalloproteinases (RU36156) led to a dramatic decrease of sCD16 production by phorbol 12-myristate 13-acetate-activated neutrophils, whereas inhibitors of serine proteinases had no significant effect, showing the metalloproteinase dependence of this cleavage process.
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Affiliation(s)
- J Galon
- INSERM U255, Institut Curie, Paris, France
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