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Dispenza MC, Metcalfe DD, Olivera A. Research Advances in Mast Cell Biology and Their Translation Into Novel Therapies for Anaphylaxis. THE JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY. IN PRACTICE 2023; 11:2032-2042. [PMID: 36958519 PMCID: PMC10330051 DOI: 10.1016/j.jaip.2023.03.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 03/07/2023] [Accepted: 03/08/2023] [Indexed: 03/25/2023]
Abstract
Anaphylaxis is an acute, potentially life-threatening systemic allergic reaction for which there are no known reliable preventative therapies. Its primary cell mediator, the mast cell, has several pathophysiologic roles and functions in IgE-mediated reactions that continue to be poorly understood. Recent advances in the understanding of allergic mechanisms have identified novel targets for inhibiting mast cell function and activation. The prevention of anaphylaxis is within reach with new drugs that could modulate immune tolerance, mast cell proliferation and differentiation, and IgE regulation and production. Several US Food and Drug Administration-approved drugs for chronic urticaria, mastocytosis, and cancer are also being repurposed to prevent anaphylaxis. New therapeutics have not only shown promise in potential efficacy for preventing IgE-mediated reactions, but in some cases, they are able to inform us about mast cell mechanisms in vivo. This review summarizes the most recent advances in the treatment of anaphylaxis that have arisen from new pharmacologic tools and our current understanding of mast cell biology.
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Affiliation(s)
- Melanie C Dispenza
- Division of Allergy and Clinical Immunology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Md.
| | - Dean D Metcalfe
- Mast Cell Biology Section, Laboratory of Allergy Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Md
| | - Ana Olivera
- Mast Cell Biology Section, Laboratory of Allergy Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Md
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Human Lung Mast Cells: Therapeutic Implications in Asthma. Int J Mol Sci 2022; 23:ijms232214466. [PMID: 36430941 PMCID: PMC9693207 DOI: 10.3390/ijms232214466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/15/2022] [Accepted: 11/18/2022] [Indexed: 11/23/2022] Open
Abstract
Mast cells are strategically located in different compartments of the lung in asthmatic patients. These cells are widely recognized as central effectors and immunomodulators in different asthma phenotypes. Mast cell mediators activate a wide spectrum of cells of the innate and adaptive immune system during airway inflammation. Moreover, these cells modulate the activities of several structural cells (i.e., fibroblasts, airway smooth muscle cells, bronchial epithelial and goblet cells, and endothelial cells) in the human lung. These findings indicate that lung mast cells and their mediators significantly contribute to the immune induction of airway remodeling in severe asthma. Therapies targeting mast cell mediators and/or their receptors, including monoclonal antibodies targeting IgE, IL-4/IL-13, IL-5/IL-5Rα, IL-4Rα, TSLP, and IL-33, have been found safe and effective in the treatment of different phenotypes of asthma. Moreover, agonists of inhibitory receptors expressed by human mast cells (Siglec-8, Siglec-6) are under investigation for asthma treatment. Increasing evidence suggests that different approaches to depleting mast cells show promising results in severe asthma treatment. Novel treatments targeting mast cells can presumably change the course of the disease and induce drug-free remission in bronchial asthma. Here, we provide an overview of current and promising treatments for asthma that directly or indirectly target lung mast cells.
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Arthur GK, Cruse G. Regulation of Trafficking and Signaling of the High Affinity IgE Receptor by FcεRIβ and the Potential Impact of FcεRIβ Splicing in Allergic Inflammation. Int J Mol Sci 2022; 23:ijms23020788. [PMID: 35054974 PMCID: PMC8776166 DOI: 10.3390/ijms23020788] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 01/06/2022] [Accepted: 01/08/2022] [Indexed: 12/23/2022] Open
Abstract
Mast cells are tissue-resident immune cells that function in both innate and adaptive immunity through the release of both preformed granule-stored mediators, and newly generated proinflammatory mediators that contribute to the generation of both the early and late phases of the allergic inflammatory response. Although mast cells can be activated by a vast array of mediators to contribute to homeostasis and pathophysiology in diverse settings and contexts, in this review, we will focus on the canonical setting of IgE-mediated activation and allergic inflammation. IgE-dependent activation of mast cells occurs through the high affinity IgE receptor, FcεRI, which is a multimeric receptor complex that, once crosslinked by antigen, triggers a cascade of signaling to generate a robust response in mast cells. Here, we discuss FcεRI structure and function, and describe established and emerging roles of the β subunit of FcεRI (FcεRIβ) in regulating mast cell function and FcεRI trafficking and signaling. We discuss current approaches to target IgE and FcεRI signaling and emerging approaches that could target FcεRIβ specifically. We examine how alternative splicing of FcεRIβ alters protein function and how manipulation of splicing could be employed as a therapeutic approach. Targeting FcεRI directly and/or IgE binding to FcεRI are promising approaches to therapeutics for allergic inflammation. The characteristic role of FcεRIβ in both trafficking and signaling of the FcεRI receptor complex, the specificity to IgE-mediated activation pathways, and the preferential expression in mast cells and basophils, makes FcεRIβ an excellent, but challenging, candidate for therapeutic strategies in allergy and asthma, if targeting can be realized.
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Affiliation(s)
- Greer K. Arthur
- Department of Population Health and Pathobiology, College of Veterinary Medicine, NC State University, Raleigh, NC 27607, USA;
| | - Glenn Cruse
- Department of Molecular Biomedical Sciences, College of Veterinary Medicine, NC State University, Raleigh, NC 27607, USA
- Correspondence: ; Tel.: +1-919-515-8865
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Kim J, Lee JY, Kim HG, Kwak MW, Kang TH. Fc Receptor Variants and Disease: A Crucial Factor to Consider in the Antibody Therapeutics in Clinic. Int J Mol Sci 2021; 22:9489. [PMID: 34502398 PMCID: PMC8431278 DOI: 10.3390/ijms22179489] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/27/2021] [Accepted: 08/28/2021] [Indexed: 12/19/2022] Open
Abstract
The fragment crystallizable (Fc) domain of antibodies is responsible for their protective function and long-lasting serum half-life via Fc-mediated effector function, transcytosis, and recycling through its interaction with Fc receptors (FcRs) expressed on various immune leukocytes, epithelial, and endothelial cells. Therefore, the Fc-FcRs interaction is a control point of both endogenous and therapeutic antibody function. There are a number of reported genetic variants of FcRs, which include polymorphisms in (i) extracellular domain of FcRs, which change their affinities to Fc domain of antibodies; (ii) both cytoplasmic and intracellular domain, which alters the extent of signal transduction; and (iii) the promoter region of the FcRs gene, which affects the expression level of FcRs, thus being associated with the pathogenesis of disease indications. In this review, we firstly describe the correlation between the genetic variants of FcRs and immunological disorders by individual differences in the extent of FcRs-mediated regulations. Secondly, we discuss the influence of the genetic variants of FcRs on the susceptibility to infectious diseases or cancer in the perspective of FcRs-induced effector functions. Overall, we concluded that the genetic variants of FcRs are one of the key elements in the design of antibody therapeutics due to their variety of clinical outcomes among individuals.
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Affiliation(s)
- Jin Kim
- Department of Interdisciplinary Program for Bio-Health Convergence, Kookmin University, Seoul 02707, Korea;
| | - Ji Young Lee
- Department of Chemistry, Kookmin University, Seoul 02707, Korea;
| | - Han Gil Kim
- Department of Biopharmaceutical Chemistry, Kookmin University, Seoul 02707, Korea; (H.G.K.); (M.W.K.)
| | - Min Woo Kwak
- Department of Biopharmaceutical Chemistry, Kookmin University, Seoul 02707, Korea; (H.G.K.); (M.W.K.)
| | - Tae Hyun Kang
- Department of Interdisciplinary Program for Bio-Health Convergence, Kookmin University, Seoul 02707, Korea;
- Department of Chemistry, Kookmin University, Seoul 02707, Korea;
- Department of Biopharmaceutical Chemistry, Kookmin University, Seoul 02707, Korea; (H.G.K.); (M.W.K.)
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Enhancement of Antibody-Dependent Cellular Cytotoxicity and Phagocytosis in Anti-HIV-1 Human-Bovine Chimeric Broadly Neutralizing Antibodies. J Virol 2021; 95:e0021921. [PMID: 33853957 DOI: 10.1128/jvi.00219-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
No prophylactic vaccine has provided robust protection against human immunodeficiency virus type 1 (HIV-1). Vaccine-induced broadly neutralizing antibodies (bNAbs) have not been achieved in humans and most animals; however, cows vaccinated with HIV-1 envelope trimers produce bNAbs with unusually long third heavy complementarity-determining regions (CDRH3s). Alongside neutralization, Fc-mediated effector functions, including antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADP), may be critical for in vivo bNAb antiviral activity. Here, we aimed to augment the Fc-dependent effector functions of a chimeric human-bovine bNAb, NC-Cow1, which binds the CD4 binding site (CD4bs) and exhibits broader and more potent neutralization than most human CD4bs bNAbs by using an exceptionally long 60-amino acid (aa) CDRH3. The bovine variable region of NC-Cow1 was paired with a human IgG1 Fc region mutated to create the following three variants: G236R/L328R (GRLR) that abrogates Fc-gamma receptor (FcγR) binding, and two variants that enhance binding, namely, G236A/S239D/I332E (GASDIE) and G236A/S239D/A330L/I332E (GASDALIE). Both GASDIE and GASDALIE improved binding to human FcγRIIA and FcγRIIIA, enhanced human natural killer (NK) cell activation, and mediated higher levels of ADCC and ADP activity than the wild-type human IgG1 Fc. GASDALIE mediated higher phagocytic activity than GASDIE. As expected, GRLR eliminated binding to FcγRs and did not mediate ADCC or ADP. We demonstrated that mutations in the human Fc region of bovine chimeric antibodies with ultralong CDRH3s could enhance antibody effector functions while maintaining envelope binding and neutralization. This study will have significant implications in the development of multifunctional anti-HIV antibodies, which may be important to prevent HIV-1 transmission in an antibody-based topical microbicide. IMPORTANCE Despite successful antiviral chemotherapy, human immunodeficiency virus (HIV) is still a lifelong persistent virus, and no vaccine yet prevents HIV transmission. Topical microbicides offer an important alternative method to prevent sexual transmission of HIV-1. With the production of highly potent anti-HIV-1 broadly neutralizing antibodies (bNAbs) and multifunctional antibodies, monoclonal antibodies are now important prophylactic agents. Recently discovered anti-HIV-1 bovine bNAbs (with higher potency and breadth than most human bNAbs) could be novel candidates as potent topical microbicides. Our study is significant as it demonstrates the compatibility of combining bovine-derived neutralization with human-derived antibody-effector functions. This study is a new approach to antibody engineering that strengthens the feasibility of using high-potency bovine variable region bNAbs with augmented Fc function and promotes them as a strong candidate for antibody-mediated therapies.
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Strategies for Mast Cell Inhibition in Food Allergy. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2020; 93:719-731. [PMID: 33380934 PMCID: PMC7757070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mast cells are tissue resident allergic effector cells that drive IgE-mediated food allergies. There are several steps leading to mast cell activation in the context of allergic disease that can be targeted to prevent mast cell activation and degranulation. These include blocking IgE-FcεRI crosslinking and type 2 cytokine receptor activation; modulating cell-surface neural chemical receptors; stabilizing mast cell membranes to prevent co-localization of activating receptors; impeding intracellular signaling; and engaging cell surface inhibitory receptors. This review highlights several ITIM-containing inhibitory mast cell surface receptors that could serve as pharmaceutical targets to prevent mast cell activation and degranulation in the context of food allergy. When activated, these ITIM-containing inhibitory receptors recruit the phosphatases SHP-1, SHP-2, and/or SHIP to dephosphorylate the tyrosine kinases responsible for activation signals downstream of the IgE-FcεRI complex. We describe several members of the Ig and Ig-like inhibitory receptor and C-type lectin inhibitory receptor superfamilies. Fundamental studies exploring the behavior of these receptors within the context of experimental food allergy models are needed. A deeper understanding of how these receptors modulate mast cell-driven food allergic responses will shape future strategies to harness these inhibitory receptors to treat food allergy.
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Vitallé J, Terrén I, Orrantia A, Bilbao A, Gamboa PM, Borrego F, Zenarruzabeitia O. The Expression and Function of CD300 Molecules in the Main Players of Allergic Responses: Mast Cells, Basophils and Eosinophils. Int J Mol Sci 2020; 21:ijms21093173. [PMID: 32365988 PMCID: PMC7247439 DOI: 10.3390/ijms21093173] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 04/17/2020] [Accepted: 04/27/2020] [Indexed: 02/06/2023] Open
Abstract
Allergy is the host immune response against non-infectious substances called allergens. The prevalence of allergic diseases is increasing worldwide. However, while some drugs counteract the symptomatology caused by allergic reactions, no completely effective treatments for allergic diseases have been developed yet. In this sense, the ability of surface activating and inhibitory receptors to modulate the function of the main effector cells of allergic responses makes these molecules potential pharmacological targets. The CD300 receptor family consists of members with activating and inhibitory capabilities mainly expressed on the surface of immune cells. Multiple studies in the last few years have highlighted the importance of CD300 molecules in several pathological conditions. This review summarizes the literature on CD300 receptor expression, regulation and function in mast cells, basophils and eosinophils, the main players of allergic responses. Moreover, we review the involvement of CD300 receptors in the pathogenesis of certain allergic diseases, as well as their prospective use as therapeutic targets for the treatment of IgE-dependent allergic responses.
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Affiliation(s)
- Joana Vitallé
- Immunopathology Group, Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain; (J.V.); (I.T.); (A.O.); (A.B.); (P.M.G.); (F.B.)
| | - Iñigo Terrén
- Immunopathology Group, Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain; (J.V.); (I.T.); (A.O.); (A.B.); (P.M.G.); (F.B.)
| | - Ane Orrantia
- Immunopathology Group, Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain; (J.V.); (I.T.); (A.O.); (A.B.); (P.M.G.); (F.B.)
| | - Agurtzane Bilbao
- Immunopathology Group, Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain; (J.V.); (I.T.); (A.O.); (A.B.); (P.M.G.); (F.B.)
- Pediatrics Service, Cruces University Hospital, 48903 Barakaldo, Spain
| | - Pedro M. Gamboa
- Immunopathology Group, Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain; (J.V.); (I.T.); (A.O.); (A.B.); (P.M.G.); (F.B.)
- Allergology Service, Cruces University Hospital, 48903 Barakaldo, Spain
| | - Francisco Borrego
- Immunopathology Group, Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain; (J.V.); (I.T.); (A.O.); (A.B.); (P.M.G.); (F.B.)
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
| | - Olatz Zenarruzabeitia
- Immunopathology Group, Biocruces Bizkaia Health Research Institute, 48903 Barakaldo, Spain; (J.V.); (I.T.); (A.O.); (A.B.); (P.M.G.); (F.B.)
- Correspondence: ; Tel.: +34-699-227-735
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Lee M, Shim SY. Inhibitory Effects of Eriodictyol-7- O- β-d-glucuronide and 5,7-Dihydroxy-4-chromene Isolated from Chrysanthemum zawadskii var. latilobum in FcεRI-Mediated Human Basophilic KU812F Cell Activation. Molecules 2020; 25:molecules25040994. [PMID: 32102220 PMCID: PMC7070965 DOI: 10.3390/molecules25040994] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 02/17/2020] [Accepted: 02/20/2020] [Indexed: 01/18/2023] Open
Abstract
Chrysanthemum zawadskii var. latilobum (CZL) has been used in Eastern medicine for the treatment of various diseases, such as pneumonia, bronchitis, cough, the common cold, pharyngitis, bladder-related disorders, gastroenteric disorders, and hypertension. In the present study, we isolated two strong antiallergic compounds from CZL, namely, eriodictyol-7-O-β-d-glucuronide (EDG) and 5,7-dihydroxy-4-chromene (DC), and investigated their antiallergic effects in FcεRI-mediated human basophilic KU812F cells. EDG and DC downregulated the protein and messenger RNA (mRNA) expression of FcεRI on the cell surface. Moreover, Western blotting analysis showed that EDG and DC inhibited the expression of protein tyrosine kinases such as Syk and Lyn, and extracellular-regulated kinases (ERK) 1/2. These results suggested that EDG and DC, antiallergic constituents of CZL, are potential therapeutic candidates for protection against and for the treatment of allergic disorders.
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Affiliation(s)
- Mina Lee
- College of Pharmacy, Sunchon National University, 255 Jungangno, Suncheon-si, Jeonnam 57922, Korea;
| | - Sun-Yup Shim
- Department of Aqualife Science, College of Fisheries and Ocean Sciences, Chonnam National University, 50 Daehak-Ro, Yeosu, Jeonnam 59626, Korea
- Correspondence: ; Tel.: +82-61-659-7160; Fax: +82-61-659-7169
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Brilland B, Scherlinger M, Khoryati L, Goret J, Duffau P, Lazaro E, Charrier M, Guillotin V, Richez C, Blanco P. Platelets and IgE: Shaping the Innate Immune Response in Systemic Lupus Erythematosus. Clin Rev Allergy Immunol 2019; 58:194-212. [DOI: 10.1007/s12016-019-08744-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Gomez G. Current Strategies to Inhibit High Affinity FcεRI-Mediated Signaling for the Treatment of Allergic Disease. Front Immunol 2019; 10:175. [PMID: 30792720 PMCID: PMC6374298 DOI: 10.3389/fimmu.2019.00175] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 01/21/2019] [Indexed: 12/11/2022] Open
Abstract
Allergies and asthma are a major cause of chronic disease whose prevalence has been on the rise. Allergic disease including seasonal rhinitis, atopic dermatitis, urticaria, anaphylaxis, and asthma, are associated with activation of tissue-resident mast cells and circulating basophils. Although these cells can be activated in different ways, allergic reactions are normally associated with the crosslinking of the high affinity Fc receptor for Immunoglobulin E, FcεRI, with multivalent antigen. Inflammatory mediators released from cytoplasmic granules, or biosynthesized de novo, following FcεRI crosslinking induce immediate hypersensitivity reactions, including life-threatening anaphylaxis, and contribute to prolonged inflammation leading to chronic diseases like asthma. Thus, inappropriate or unregulated activation of mast cells and basophils through antigenic crosslinking of FcεRI can have deleterious, sometimes deadly, consequences. Accordingly, FcεRI has emerged as a viable target for the development of biologics that act to inhibit or attenuate the activation of mast cells and basophils. At the forefront of these strategies are (1) Anti-IgE monoclonal antibody, namely omalizumab, which has the secondary effect of reducing FcεRI surface expression, (2) Designed Ankyrin Repeat Proteins (DARPins), which take advantage of the most common structural motifs in nature involved in protein-protein interactions, to inhibit FcεRI-IgE interactions, and (3) Fusion proteins to co-aggregate FcεRI with the inhibitory FcγRIIb. This review presents the published research studies that support omalizumab, DARPins, and fusion proteins as, arguably, the three most currently viable strategies for inhibiting the expression and activation of the high affinity FcεRI on mast cells and basophils.
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Affiliation(s)
- Gregorio Gomez
- Department of Pathology, Microbiology and Immunology, University of South Carolina School of Medicine, Columbia, SC, United States
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Imperatorin Suppresses Anaphylactic Reaction and IgE-Mediated Allergic Responses by Inhibiting Multiple Steps of FceRI Signaling in Mast Cells: IMP Alleviates Allergic Responses in PCA. BIOMED RESEARCH INTERNATIONAL 2019; 2019:7823761. [PMID: 30800677 PMCID: PMC6360561 DOI: 10.1155/2019/7823761] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 11/27/2018] [Indexed: 12/17/2022]
Abstract
This study is to investigate the effects of imperatorin (IMP) on allergic responses mediated by mast cells, both in vitro and in vivo. Passive cutaneous anaphylaxis (PCA) model was established. Histological detection was performed to assess the ear histology. ELISA and Western blot analysis were used to detect the levels of corresponding cytokines and signalling pathway proteins. IMP decreased the leakage of Evans blue and the ear thickness in the PCA models, in a dose-dependent manner, and alleviated the degranulation of mast cells. Moreover, IMP reduced the expression of TNF-α, IL-4, IL-1β, IL-8, and IL-13. Furthermore, IMP inhibited the phosphorylation levels of Syk, Lyn, PLC-γ1, and Gab2, as well as the downstream MAPK, PI3K/AKT, and NF-κB signaling pathways. In addition, IMP inhibited the mast cell-mediated allergic responses through the Nrf2/HO-1 pathway. IMP attenuates the allergic responses through inhibiting the degranulation and decreasing the expression levels of proinflammatory cytokines in the mast cells, involving the PI3K/Akt, MAPK, NF-κB, and Nrf2/HO-1 pathways.
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12
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Varricchi G, Raap U, Rivellese F, Marone G, Gibbs BF. Human mast cells and basophils-How are they similar how are they different? Immunol Rev 2019; 282:8-34. [PMID: 29431214 DOI: 10.1111/imr.12627] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mast cells and basophils are key contributors to allergies and other inflammatory diseases since they are the most prominent source of histamine as well as numerous additional inflammatory mediators which drive inflammatory responses. However, a closer understanding of their precise roles in allergies and other pathological conditions has been marred by the considerable heterogeneity that these cells display, not only between mast cells and basophils themselves but also across different tissue locations and species. While both cell types share the ability to rapidly degranulate and release histamine following high-affinity IgE receptor cross-linking, they differ markedly in their ability to either react to other stimuli, generate inflammatory eicosanoids or release immunomodulating cytokines and chemokines. Furthermore, these cells display considerable pharmacological heterogeneity which has stifled attempts to develop more effective anti-allergic therapies. Mast cell- and basophil-specific transcriptional profiling, at rest and after activation by innate and adaptive stimuli, may help to unravel the degree to which these cells differ and facilitate a clearer understanding of their biological functions and how these could be targeted by new therapies.
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Affiliation(s)
- Gilda Varricchi
- Department of Translational Medical Sciences and Center for Basic and Clinical Immunology Research, University of Naples Federico II, Naples, Italy.,WAO Center of Excellence, Naples, Italy
| | - Ulrike Raap
- Department of Dermatology and Allergology, University of Oldenburg, Oldenburg, Germany
| | - Felice Rivellese
- Department of Translational Medical Sciences and Center for Basic and Clinical Immunology Research, University of Naples Federico II, Naples, Italy.,WAO Center of Excellence, Naples, Italy.,Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Gianni Marone
- Department of Translational Medical Sciences and Center for Basic and Clinical Immunology Research, University of Naples Federico II, Naples, Italy.,WAO Center of Excellence, Naples, Italy.,Institute of Experimental Endocrinology and Oncology "Gaetano Salvatore" (IEOS), National Research Council (CNR), Naples, Italy
| | - Bernhard F Gibbs
- Department of Dermatology and Allergology, University of Oldenburg, Oldenburg, Germany
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Liu QM, Xie CL, Gao YY, Liu B, Lin WX, Liu H, Cao MJ, Su WJ, Yang XW, Liu GM. Deep-Sea-Derived Butyrolactone I Suppresses Ovalbumin-Induced Anaphylaxis by Regulating Mast Cell Function in a Murine Model. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:5581-5592. [PMID: 29763312 DOI: 10.1021/acs.jafc.8b01674] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Deep-sea-derived butyrolactone I (BTL-I), which was identified as a type of butanolide, was isolated from Aspergillus sp. Ovalbumin (OVA)-induced BALB/c anaphylaxis was established to explore the antifood allergic activity of BTL-I. As a result, BTL-I was able to alleviate OVA-induced allergy symptoms, reduce the levels of histamine and mouse mast cell proteinases, inhibit OVA-specific IgE, and decrease the population of mast cells in the spleen and mesenteric lymph nodes. BTL-I also significantly suppressed mast-dependent passive cutaneous anaphylaxis. Additionally, the maturation of bone marrow-derived mast cells (BMMCs) declined as BTL-I caused down-regulation of c-KIT receptors. Furthermore, molecular docking analyses revealed that BTL-I interacted with the inhibitory receptor, FcγRIIB. In conclusion, the reduction of mast cell function by deep-sea-derived BTL-I as well as its interactions with the inhibitory receptor, FcγRIIB, may contribute to BTL-I-related protection against food anaphylaxis.
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Affiliation(s)
- Qing-Mei Liu
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources , Jimei University , 43 Yindou Road , Xiamen , 361021 Fujian , P.R. China
| | - Chun-Lan Xie
- Key Laboratory of Marine Biogenetic Resources, South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center , Third Institute of Oceanography, State Oceanic Administration , 184 Daxue Road , Xiamen , 361005 Fujian , P.R. China
| | - Yuan-Yuan Gao
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources , Jimei University , 43 Yindou Road , Xiamen , 361021 Fujian , P.R. China
| | - Bo Liu
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources , Jimei University , 43 Yindou Road , Xiamen , 361021 Fujian , P.R. China
| | - Wei-Xiang Lin
- Key Laboratory of Marine Biogenetic Resources, South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center , Third Institute of Oceanography, State Oceanic Administration , 184 Daxue Road , Xiamen , 361005 Fujian , P.R. China
| | - Hong Liu
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources , Jimei University , 43 Yindou Road , Xiamen , 361021 Fujian , P.R. China
| | - Min-Jie Cao
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources , Jimei University , 43 Yindou Road , Xiamen , 361021 Fujian , P.R. China
| | - Wen-Jin Su
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources , Jimei University , 43 Yindou Road , Xiamen , 361021 Fujian , P.R. China
| | - Xian-Wen Yang
- Key Laboratory of Marine Biogenetic Resources, South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center , Third Institute of Oceanography, State Oceanic Administration , 184 Daxue Road , Xiamen , 361005 Fujian , P.R. China
| | - Guang-Ming Liu
- College of Food and Biological Engineering, Xiamen Key Laboratory of Marine Functional Food, Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources , Jimei University , 43 Yindou Road , Xiamen , 361021 Fujian , P.R. China
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14
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Chirumbolo S, Bjørklund G, Sboarina A, Vella A. The role of basophils as innate immune regulatory cells in allergy and immunotherapy. Hum Vaccin Immunother 2018; 14:815-831. [PMID: 29257936 DOI: 10.1080/21645515.2017.1417711] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Basophils are circulating cells that are associated quite exclusively with allergy response and hypersensitivity reactions but their role in the immune network might be much more intriguing and complex than previously expected. The feasibility of testing their biology in vitro for allergy research and diagnosis, due fundamentally to their quite easy availability in the peripheral blood, made them the major source for assessing allergy in the laboratory assay, when yet many further cells such as mast cells and eosinophils are much more involved as effector cells in allergy than circulating basophils. Interestingly, basophil numbers change rarely in peripheral blood during an atopic response, while we might yet observe an increase in eosinophils and modification in the biology of mast cells in the tissue during an hypersensitivity response. Furthermore, the fact that basophils are very scanty in numbers suggests that they should mainly serve as regulatory cells in immunity, rather than effector leukocytes, as still believed by the majority of physicians. In this review we will try to describe and elucidate the possible role of these cells, known as "innate IL4-producing cells" in the immune regulation of allergy and their function in allergen immunotherapy.
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Affiliation(s)
- Salvatore Chirumbolo
- a Department of Neurological and Movement Sciences , University of Verona , Verona , Italy
| | - Geir Bjørklund
- b Council for Nutritional and Environmental Medicine (CONEM) , Mo i Rana , Norway
| | - Andrea Sboarina
- c Department of Surgery , Dentistry, Paediatrics and Gynaecology-University of Verona , Verona , Italy
| | - Antonio Vella
- d Unit of Immunology-Azienda Ospedaliera Universitaria Integrata (AOUI) , Verona , Italy
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15
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Zellweger F, Gasser P, Brigger D, Buschor P, Vogel M, Eggel A. A novel bispecific DARPin targeting FcγRIIB and FcεRI-bound IgE inhibits allergic responses. Allergy 2017; 72:1174-1183. [PMID: 27997998 DOI: 10.1111/all.13109] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2016] [Indexed: 01/30/2023]
Abstract
BACKGROUND Binding of allergen-specific IgE to its high-affinity receptor FcεRI on basophils and mast cells is a central event in the development of allergies. Exposure of these cells to allergens induces the release of soluble mediators causing allergic symptoms. The inhibitory low-affinity IgG Fc-receptor FcγRIIB is co-expressed on allergic effector cells and has been implicated in negative regulation of immediate hypersensitivity responses. In order to harvest the inhibitory function of this receptor, we aimed to select specific binders against FcγRIIB and to generate a bispecific molecule simultaneously targeting FcγRIIB and FcεRI-bound IgE on the surface of allergic effector cells. METHODS We selected FcγRIIB-specific binding molecules from a library of designed ankyrin repeat proteins using ribosome display technology. The bispecific binding modality was generated by molecular cloning and recombinant protein expression. We determined binding characteristics on molecular and cellular levels using SPR, ELISA, and flow cytometry. The inhibitory potential of the newly described molecules was assessed in different cellular degranulation assays ex vivo and in a mouse model of passive systemic anaphylaxis. RESULTS We demonstrate that the selected DARPin® proteins recognize FcγRIIB with high affinity. Furthermore, the bispecific binding protein successfully interferes with allergen-induced cell degranulation and efficiently inhibits systemic anaphylaxis in vivo. Mechanistically, we report that FcγRIIB-mediated inhibition of effector cell activation requires direct ligation to an activating FcεRI receptor. CONCLUSION The described bispecific DARPin protein has the ability to co-ligate FcγRIIB with FcεRI-bound IgE on allergic effector cells and represents an efficient dual-modality to interfere with allergic hypersensitivity reactions.
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Affiliation(s)
- F. Zellweger
- Department of Clinical Research; University of Bern; Bern Switzerland
- Department of Rheumatology, Immunology and Allergology; University Hospital Bern; Bern Switzerland
| | - P. Gasser
- Department of Clinical Research; University of Bern; Bern Switzerland
- Department of Rheumatology, Immunology and Allergology; University Hospital Bern; Bern Switzerland
| | - D. Brigger
- Department of Clinical Research; University of Bern; Bern Switzerland
- Department of Rheumatology, Immunology and Allergology; University Hospital Bern; Bern Switzerland
| | - P. Buschor
- Institute of Immunology; University of Bern; Bern Switzerland
| | - M. Vogel
- Department of Clinical Research; University of Bern; Bern Switzerland
- Department of Rheumatology, Immunology and Allergology; University Hospital Bern; Bern Switzerland
| | - A. Eggel
- Department of Clinical Research; University of Bern; Bern Switzerland
- Department of Rheumatology, Immunology and Allergology; University Hospital Bern; Bern Switzerland
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16
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Abstract
Mouse and human FcRs have been a major focus of attention not only of the scientific community, through the cloning and characterization of novel receptors, and of the medical community, through the identification of polymorphisms and linkage to disease but also of the pharmaceutical community, through the identification of FcRs as targets for therapy or engineering of Fc domains for the generation of enhanced therapeutic antibodies. The availability of knockout mouse lines for every single mouse FcR, of multiple or cell-specific--'à la carte'--FcR knockouts and the increasing generation of hFcR transgenics enable powerful in vivo approaches for the study of mouse and human FcR biology. This review will present the landscape of the current FcR family, their effector functions and the in vivo models at hand to study them. These in vivo models were recently instrumental in re-defining the properties and effector functions of FcRs that had been overlooked or discarded from previous analyses. A particular focus will be made on the (mis)concepts on the role of high-affinity IgG receptors in vivo and on results from antibody engineering to enhance or abrogate antibody effector functions mediated by FcRs.
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Affiliation(s)
- Pierre Bruhns
- Unité des Anticorps en Thérapie et Pathologie, Département d'Immunologie, Institut Pasteur, Paris, France.,INSERM, U760, Paris, France
| | - Friederike Jönsson
- Unité des Anticorps en Thérapie et Pathologie, Département d'Immunologie, Institut Pasteur, Paris, France.,INSERM, U760, Paris, France
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17
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A rapid and sensitive assay based on particle analysis for cell degranulation detection in basophils and mast cells. Pharmacol Res 2016; 111:374-383. [PMID: 27339828 DOI: 10.1016/j.phrs.2016.05.033] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/24/2016] [Accepted: 05/30/2016] [Indexed: 01/02/2023]
Abstract
The degranulation of mast cells and basophils is often initiated by a number of pathophysiological responses, especially in allergic and inflammatory conditions. Efficient techniques and methods for determining the level of such degranulation are highly demanded for laboratory and clinical studies. In this work, a rapid and sensitive assay based on the particle analysis of granules in RBL-2H3 cells, a cell line widely used as a convenient model system to study the degranulation of mast cells and basophils, was developed to detect cell degranulation using a Nanosight NS300 in light scatter mode and dynamic light scattering (DLS) on a Malvern Zetasizer Nano-ZS instrument. Using this method, drug-induced mast cell degranulation and systemic anaphylaxis were efficiently determined both in cell culture medium and blood samples from animals in the current study. This promising method is expected to be widely used for screening anti-allergic and anti-inflammatory drugs both in vitro and in vivo models, as well as for determining the level of mast cell degranulation of the patients in the clinic.
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18
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Gangwar RS, Friedman S, Seaf M, Levi-Schaffer F. Mast cells and eosinophils in allergy: Close friends or just neighbors. Eur J Pharmacol 2016; 778:77-83. [DOI: 10.1016/j.ejphar.2015.10.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 09/21/2015] [Accepted: 10/21/2015] [Indexed: 12/15/2022]
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19
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Blank U, Charles N, Benhamou M. The high-affinity immunoglobulin E receptor as pharmacological target. Eur J Pharmacol 2016; 778:24-32. [DOI: 10.1016/j.ejphar.2015.05.070] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Revised: 04/29/2015] [Accepted: 05/17/2015] [Indexed: 01/02/2023]
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20
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IgE als Zielstruktur für therapeutische Intervention. ALLERGOLOGIE 2016. [DOI: 10.1007/978-3-642-37203-2_58] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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21
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Zhang T, Finn DF, Barlow JW, Walsh JJ. Mast cell stabilisers. Eur J Pharmacol 2015; 778:158-68. [PMID: 26130122 DOI: 10.1016/j.ejphar.2015.05.071] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 05/05/2015] [Accepted: 05/17/2015] [Indexed: 01/18/2023]
Abstract
Mast cells play a critical role in type 1 hypersensitivity reactions. Indeed, mast cell mediators are implicated in many different conditions including allergic rhinitis, conjunctivitis, asthma, psoriasis, mastocytosis and the progression of many different cancers. Thus, there is intense interest in the development of agents which prevent mast cell mediator release or which inhibit the actions of such mediators once released into the environment of the cell. Much progress into the design of new agents has been made since the initial discovery of the mast cell stabilising properties of khellin from Ammi visnaga and the clinical approval of cromolyn sodium. This review critically examines the progress that has been made in the intervening years from the design of new agents that target a specific signalling event in the mast cell degranulation pathway to those agents which have been developed where the precise mechanism of action remains elusive. Particular emphasis is also placed on clinically used drugs for other indications that stabilise mast cells and how this additional action may be harnessed for their clinical use in disease processes where mast cells are implicated.
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Affiliation(s)
- Tao Zhang
- School of Pharmacy and Pharmaceutical Sciences, Trinity College Dublin, Dublin 2, Ireland
| | - Deirdre Frances Finn
- School of Pharmacy and Pharmaceutical Sciences, Trinity College Dublin, Dublin 2, Ireland
| | - James William Barlow
- Department of Pharmaceutical & Medicinal Chemistry, Royal College of Surgeons in Ireland, Stephens Green, Dublin 2, Ireland
| | - John Jarlath Walsh
- School of Pharmacy and Pharmaceutical Sciences, Trinity College Dublin, Dublin 2, Ireland.
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22
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Mast cell and autoimmune diseases. Mediators Inflamm 2015; 2015:246126. [PMID: 25944979 PMCID: PMC4402170 DOI: 10.1155/2015/246126] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 03/25/2015] [Accepted: 03/25/2015] [Indexed: 01/04/2023] Open
Abstract
Mast cells are important in innate immune system. They have been appreciated as potent contributors to allergic reaction. However, increasing evidence implicates the important role of mast cells in autoimmune disease like rheumatoid arthritis and multiple sclerosis. Here we review the current stage of knowledge about mast cells in autoimmune diseases.
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23
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Landolina N, Gangwar RS, Levi-Schaffer F. Mast cells' integrated actions with eosinophils and fibroblasts in allergic inflammation: implications for therapy. Adv Immunol 2015; 125:41-85. [PMID: 25591464 DOI: 10.1016/bs.ai.2014.09.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mast cells (MCs) and eosinophils (Eos) are the key players in the development of allergic inflammation (AI). Their cross-talk, named the Allergic Effector Unit (AEU), takes place through an array of soluble mediators and ligands/receptors interactions that enhance the functions of both the cells. One of the salient features of the AEU is the CD48/2B4 receptor/ligand binding complex. Furthermore, MCs and Eos have been demonstrated to play a role not only in AI but also in the modulation of its consequence, i.e., fibrosis/tissue remodeling, by directly influencing fibroblasts (FBs), the main target cells of these processes. In turn, FBs can regulate the survival, activity, and phenotype of both MCs and Eos. Therefore, a complex three players, MCs/Eos/FBs interaction, can take place in various stages of AI. The characterization of the soluble and physical mediated cross talk among these three cells might lead to the identification of both better and novel targets for the treatment of allergy and its tissue remodeling consequences.
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Affiliation(s)
- Nadine Landolina
- Department of Pharmacology, Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Roopesh Singh Gangwar
- Department of Pharmacology, Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Francesca Levi-Schaffer
- Department of Pharmacology, Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel.
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24
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Wilson CJ. Rational protein design: developing next‐generation biological therapeutics and nanobiotechnological tools. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2014; 7:330-41. [DOI: 10.1002/wnan.1310] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 09/02/2014] [Indexed: 01/22/2023]
Affiliation(s)
- Corey J. Wilson
- Department of Chemical and Environmental EngineeringYale UniversityNew HavenCTUSA
- Department of Molecular Biochemistry and BiophysicsYale UniversityNew HavenCTUSA
- Department of Biomedical EngineeringYale UniversityNew HavenCTUSA
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25
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Molecular targets on mast cells and basophils for novel therapies. J Allergy Clin Immunol 2014; 134:530-44. [DOI: 10.1016/j.jaci.2014.03.007] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 02/24/2014] [Accepted: 03/07/2014] [Indexed: 01/14/2023]
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26
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Mimoto F, Katada H, Kadono S, Igawa T, Kuramochi T, Muraoka M, Wada Y, Haraya K, Miyazaki T, Hattori K. Engineered antibody Fc variant with selectively enhanced FcγRIIb binding over both FcγRIIa(R131) and FcγRIIa(H131). Protein Eng Des Sel 2013; 26:589-98. [PMID: 23744091 PMCID: PMC3785249 DOI: 10.1093/protein/gzt022] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Revised: 04/24/2013] [Accepted: 05/08/2013] [Indexed: 12/02/2022] Open
Abstract
Engaging inhibitory FcγRIIb by Fc region has been recently reported to be an attractive approach for improving the efficacy of antibody therapeutics. However, the previously reported S267E/L328F variant with enhanced binding affinity to FcγRIIb, also enhances binding affinity to FcγRIIa(R131) allotype to a similar degree because FcγRIIb and FcγRIIa(R131) are structurally similar. In this study, we applied comprehensive mutagenesis and structure-guided design based on the crystal structure of the Fc/FcγRIIb complex to identify a novel Fc variant with selectively enhanced FcγRIIb binding over both FcγRIIa(R131) and FcγRIIa(H131). This novel variant has more than 200-fold stronger binding affinity to FcγRIIb than wild-type IgG1, while binding affinity to FcγRIIa(R131) and FcγRIIa(H131) is comparable with or lower than wild-type IgG1. This selectivity was achieved by conformational change of the C(H)2 domain by mutating Pro to Asp at position 238. Fc variant with increased binding to both FcγRIIb and FcγRIIa induced platelet aggregation and activation in an immune complex form in vitro while our novel variant did not. When applied to agonistic anti-CD137 IgG1 antibody, our variant greatly enhanced the agonistic activity. Thus, the selective enhancement of FcγRIIb binding achieved by our Fc variant provides a novel tool for improving the efficacy of antibody therapeutics.
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Affiliation(s)
| | | | | | - T. Igawa
- Research Division, Chugai Pharmaceutical Co., Ltd., Gotemba, Shizuoka, Japan
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