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Tsugawa N, Yamada D, Watabe T, Onizawa M, Wang S, Nemoto Y, Oshima S, Tsubata T, Adachi T, Kawano Y, Watanabe M, Blumberg RS, Okamoto R, Nagaishi T. CEACAM1 specifically suppresses B cell receptor signaling-mediated activation. Biochem Biophys Res Commun 2021; 535:99-105. [PMID: 33352461 PMCID: PMC9635307 DOI: 10.1016/j.bbrc.2020.11.126] [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: 11/23/2020] [Accepted: 11/30/2020] [Indexed: 01/28/2023]
Abstract
Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) expressed in T cells may regulate immune responses in the gut. In addition to T cells, B cells are also an important population in the gut-associated lymphoid tissues that orchestrate mucosal homeostasis. However, the role of CEACAM1 in B cells has not been elucidated. We herein analyzed mature B cells to determine the functions of CEACAM1. Flow cytometry revealed high expression of CEACAM1 on B cells in secondary lymphoid tissues. Cytokine production induced by activation of B cell receptor (BCR) signaling was suppressed by CEACAM1 signaling in contrast to that associated with either Toll-like receptor 4 or CD40 signaling. Confocal microscopy revealed co-localization of CEACAM1 and BCR when activated with anti-Igμ F(ab')2 fragment. Overexpression of CEACAM1 in a murine B cell line, A20, resulted in reduced expressions of activation surface markers with decreased Ca2+ influx after BCR signal activation. Overexpression of CEACAM1 suppressed BCR signal cascade in A20 cells in association with decreased spontaneous proliferation. Our results suggest that CEACAM1 can regulate BCR-mediated mature B cell activation in lymphoid tissues. Therefore, further studies of this molecule may lead to greater insights into the mechanisms of immune responses within peripheral tissues and the potential treatment of inflammatory diseases.
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Affiliation(s)
- Naoya Tsugawa
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Daiki Yamada
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Taro Watabe
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Michio Onizawa
- Department of Advanced Therapeutics for GI Diseases, Graduate School of Medical Science, TMDU, Tokyo, Japan
| | - Shuang Wang
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan; Faculty of Medicine, Imperial College London, London, UK
| | - Yasuhiro Nemoto
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan; Department of Advanced Therapeutics for GI Diseases, Graduate School of Medical Science, TMDU, Tokyo, Japan
| | - Shigeru Oshima
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Takeshi Tsubata
- Department of Immunology, Medical Research Institute (MRI), TMDU, Tokyo, Japan
| | - Takahiro Adachi
- Department of Immunology, Medical Research Institute (MRI), TMDU, Tokyo, Japan
| | - Yohei Kawano
- Department of Immune Regulation, Graduate School of Medical Science, TMDU, Tokyo, Japan
| | - Mamoru Watanabe
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan; Advanced Research Institute, TMDU, Tokyo, Japan
| | - Richard S Blumberg
- Gastroenterology Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Ryuichi Okamoto
- Department of Gastroenterology, Graduate School of Medical Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Takashi Nagaishi
- Department of Advanced Therapeutics for GI Diseases, Graduate School of Medical Science, TMDU, Tokyo, Japan.
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Wasim L, Buhari FHM, Yoganathan M, Sicard T, Ereño-Orbea J, Julien JP, Treanor B. N-Linked Glycosylation Regulates CD22 Organization and Function. Front Immunol 2019; 10:699. [PMID: 31019513 PMCID: PMC6458307 DOI: 10.3389/fimmu.2019.00699] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Accepted: 03/14/2019] [Indexed: 11/29/2022] Open
Abstract
The organization and clustering of cell surface proteins plays a critical role in controlling receptor signaling; however, the biophysical mechanisms regulating these parameters are not well understood. Elucidating these mechanisms is highly significant to our understanding of immune function in health and disease, given the importance of B cell receptor (BCR) signaling in directing B cells to produce antibodies for the clearance of pathogens, and the potential deleterious effects of dysregulated BCR signaling, such as in B cell malignancies or autoimmune disease. One of main inhibitory co-receptors on B cells is CD22, a sialic-acid binding protein, which interacts homotypically with other sialylated CD22 molecules, as well as heterotypically with IgM and CD45. Although the importance of CD22 in attenuating BCR signaling is well established, we still do not fully understand what mediates CD22 organization and association to BCRs. CD22 is highly glycosylated, containing 12 N-linked glycosylation sites on its extracellular domain, the function of which remain to be resolved. We were interested in how these glycosylation sites mediate homotypic vs. heterotypic interactions. To this end, we mutated five out of the six N-linked glycosylation residues on CD22 localized closest to the sialic acid binding site. Glycan site N101 was not mutated as this resulted in lack of CD22 expression. We used dual-color super-resolution imaging to investigate the impact of altered glycosylation of CD22 on the nanoscale organization of CD22 and its association with BCR. We show that mutation of these five glycosylation sites increased the clustering tendency of CD22 and resulted in higher density CD22 nanoclusters. Consistent with these findings of altered CD22 organization, we found that mutation of N-glycan sites attenuated CD22 phosphorylation upon BCR stimulation, and consequently, increased BCR signaling. Importantly, we identified that these sites may be ligands for the soluble secreted lectin, galectin-9, and are necessary for galectin-9 mediated inhibition of BCR signaling. Taken together, these findings implicate N-linked glycosylation in the organization and function of CD22, likely through regulating heterotypic interactions between CD22 and its binding partners.
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Affiliation(s)
- Laabiah Wasim
- Department of Immunology, University of Toronto, Toronto, ON, Canada
| | | | - Myuran Yoganathan
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
| | - Taylor Sicard
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - June Ereño-Orbea
- The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Jean-Philippe Julien
- Department of Immunology, University of Toronto, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,The Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Bebhinn Treanor
- Department of Immunology, University of Toronto, Toronto, ON, Canada.,Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.,Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
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Chang CH, Wang Y, Gupta P, Goldenberg DM. Extensive crosslinking of CD22 by epratuzumab triggers BCR signaling and caspase-dependent apoptosis in human lymphoma cells. MAbs 2015; 7:199-211. [PMID: 25484043 PMCID: PMC4622945 DOI: 10.4161/19420862.2014.979081] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Epratuzumab has demonstrated therapeutic activity in patients with non-Hodgkin lymphoma, acute lymphoblastic leukemia, systemic lupus erythematosus, and Sjögren's syndrome, but its mechanism of affecting normal and malignant B cells remains incompletely understood. We reported previously that epratuzumab displayed in vitro cytotoxicity to CD22-expressing Burkitt lymphoma cell lines (Daudi and Ramos) only when immobilized on plates or combined with a crosslinking antibody plus a suboptimal amount of anti-IgM (1 μg/mL). Herein, we show that, in the absence of additional anti-IgM ligation, extensive crosslinking of CD22 by plate-immobilized epratuzumab induced intracellular changes in Daudi cells similar to ligating B-cell antigen receptor with a sufficiently high amount of anti-IgM (10 μg/mL). Specifically, either treatment led to phosphorylation of CD22, CD79a and CD79b, along with their translocation to lipid rafts, both of which were essential for effecting caspase-dependent apoptosis. Moreover, such immobilization induced stabilization of F-actin, phosphorylation of Lyn, ERKs and JNKs, generation of reactive oxygen species (ROS), decrease in mitochondria membrane potential (Δψm), upregulation of pro-apoptotic Bax, and downregulation of anti-apoptotic Bcl-xl and Mcl-1. The physiological relevance of immobilized epratuzumab was implicated by noting that several of its in vitro effects, including apoptosis, drop in Δψm, and generation of ROS, could be observed with soluble epratuzumab in Daudi cells co-cultivated with human umbilical vein endothelial cells. These results suggest that the in vivo mechanism of non-ligand-blocking epratuzumab may, in part, involve the unmasking of CD22 to facilitate the trans-interaction of B cells with vascular endothelium.
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Key Words
- 488-annexin V, Alexa Fluor 488-conjugated annexin V
- 7-AAD, 7-aminoactinomycin D, Syk, spleen tyrosine kinase
- Anti-IgM, F(ab’)2 fragment of affinity-purified goat anti-human IgM, Fc5μ fragment
- BCR
- BCR, B-cell antigen receptor
- BSA, bovine serum albumin
- CD22
- CM-H2DCF-DA, 2′,7′-dichlorodihydrofluorescein diacetate
- DNP, 2,4-dinitrophenyl
- EC, endothelial cells
- ERKs, extracellular signal-regulated kinases
- FBS, fetal bovine serum
- FITC-DNase I, fluorescein isothiocyanate-conjugated DNase I
- GAH, F(ab′)2 fragment of affinity-purified goat anti-human IgG Fcγ fragment-specific
- HUV-EC
- HUV-EC, human umbilical vein endothelial cells
- ITIM, immunoreceptor tyrosine-based inhibition motif
- JNKs, c-Jun N-terminal kinases
- JP, jasplakinolide
- LatB, latrunculin B
- Lyn, Lck/Yes novel tyrosine kinase
- MAP kinases, mitogen-activated protein kinases
- MTS, (3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium
- PARP, poly(ADP-ribose) polymerase
- PBS, phosphate-buffered saline
- PLCγ2, phospholipase C, isotype gamma 2
- ROS, reactive oxygen species
- Rhodamine-anti-IgG, rhodamine-conjugated F(ab′)2 fragment of affinity-purified goat anti-human IgG, F(ab′)2 fragment-specific
- TMRE/tetramethylrhodamine/ethyl ester
- epratuzumab
- human B-cell lymphoma
- immobilized
- mIgM, membrane IgM
- Δψm, mitochondria membrane potential
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Dörner T, Shock A, Goldenberg DM, Lipsky PE. The mechanistic impact of CD22 engagement with epratuzumab on B cell function: Implications for the treatment of systemic lupus erythematosus. Autoimmun Rev 2015. [PMID: 26212727 DOI: 10.1016/j.autrev.2015.07.013] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Epratuzumab is a B-cell-directed non-depleting monoclonal antibody that targets CD22. It is currently being evaluated in two phase 3 clinical trials in patients with systemic lupus erythematosus (SLE), a disease associated with abnormalities in B-cell function and activation. The mechanism of action of epratuzumab involves perturbation of the B-cell receptor (BCR) signalling complex and intensification of the normal inhibitory role of CD22 on the BCR, leading to reduced signalling and diminished activation of B cells. Such effects may result from down-modulation of CD22 upon binding by epratuzumab, as well as decreased expression of other proteins involved in amplifying BCR signalling capability, notably CD19. The net result is blunting the capacity of antigen engagement to induce B-cell activation. The functional consequences of epratuzumab binding to CD22 include diminished B-cell proliferation, effects on adhesion molecule expression, and B-cell migration, as well as reduced production of pro-inflammatory cytokines, such as IL-6 and TNF. Studies in patients treated with epratuzumab have revealed a number of pharmacodynamic effects that are linked to the mechanism of action (i.e., a loss of the target molecule CD22 from the B-cell surface followed by a modest reduction in peripheral B-cell numbers after prolonged therapy). Together, these data indicate that epratuzumab therapy affords a unique means to modulate BCR complex expression and signalling.
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Affiliation(s)
- Thomas Dörner
- Department of Medicine/Rheumatology and Clinical Immunology, Charité Berlin and DRFZ Berlin, 10117 Berlin, Germany.
| | - Anthony Shock
- UCB Pharma, 208 Bath Road, Slough, West Berkshire, SL1 3WE, UK.
| | | | - Peter E Lipsky
- Formerly National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA.
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Paulson JC, Macauley MS, Kawasaki N. Siglecs as sensors of self in innate and adaptive immune responses. Ann N Y Acad Sci 2012; 1253:37-48. [PMID: 22288608 DOI: 10.1111/j.1749-6632.2011.06362.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Siglecs are expressed on most white blood cells of the immune system and are known to modulate the activity of cell signaling receptors via regulatory motifs in their cytoplasmic domains. This immunoglobulin subfamily of coreceptors recognize sialic acid containing glycans as ligands, which are found on glycoproteins and glycolipids of all mammalian cells. By virtue of their ability to recognize this common structural element, siglecs are increasingly recognized for their ability to help immune cells distinguish between self and nonself, and dampen autoimmune responses.
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Affiliation(s)
- James C Paulson
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA.
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Adachi T, Harumiya S, Takematsu H, Kozutsumi Y, Wabl M, Fujimoto M, Tedder TF. CD22 serves as a receptor for soluble IgM. Eur J Immunol 2011; 42:241-7. [PMID: 21956693 DOI: 10.1002/eji.201141899] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 08/16/2011] [Accepted: 09/20/2011] [Indexed: 01/01/2023]
Abstract
CD22 (Siglec-2) is a B-cell membrane-bound lectin that recognizes glycan ligands containing α2,6-linked sialic acid (α2,6Sia) and negatively regulates signaling through the B-cell Ag receptor (BCR). Although CD22 has been investigated extensively, its precise function remains unclear due to acting multiple phases. Here, we demonstrate that CD22 is efficiently activated in trans by complexes of Ag and soluble IgM (sIgM) due to the presence of glycan ligands on sIgM. This result strongly suggests sIgM as a natural trans ligand for CD22. Also, CD22 appears to serve as a receptor for sIgM, which induces a negative feedback loop for B-cell activation similar to the Fc receptor for IgG (FcγRIIB).
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Affiliation(s)
- Takahiro Adachi
- Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan.
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Hanashima S, Sato KI, Naito Y, Takematsu H, Kozutsumi Y, Ito Y, Yamaguchi Y. Synthesis and binding analysis of unique AG2 pentasaccharide to human Siglec-2 using NMR techniques. Bioorg Med Chem 2010; 18:3720-5. [DOI: 10.1016/j.bmc.2010.03.062] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Revised: 03/19/2010] [Accepted: 03/25/2010] [Indexed: 10/19/2022]
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Toda M, Nakada H. Immunosuppressive Effect of Carcinoma-Produced Mucins on B Cell Function. TRENDS GLYCOSCI GLYC 2010. [DOI: 10.4052/tigg.22.226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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10
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Abdu-Allah HHM, Tamanaka T, Yu J, Zhuoyuan L, Sadagopan M, Adachi T, Tsubata T, Kelm S, Ishida H, Kiso M. Design, synthesis, and structure-affinity relationships of novel series of sialosides as CD22-specific inhibitors. J Med Chem 2008; 51:6665-81. [PMID: 18841881 DOI: 10.1021/jm8000696] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Sialosides incorporating substituted amides or amines at 9-position of sialic acid moiety have been synthesized and evaluated as CD22 inhibitors. Several derivatives exhibited inhibitory potency in sub- to low micromolar range (e. g., 8o, 9d, 9g, and 9k showed IC 50 values 0.40, 0.47, 0.24, and 0.23 microM, respectively, for hCD22, while 8p, 8q, and 9f, showed IC 50 values 1.70, 2.90, and 4.10 microM, respectively, for mCD22). The most significant result was the strongly enhanced affinity of 9g and 9k containing 9-(2' or 4'-hydroxy-4-biphenyl) methylamino substituents (600-fold more potent for hCD22 than the corresponding 9-hydroxy derivative; 7a). Molecular modeling study was carried out to get some insights into the molecular basis of CD22 inhibition. To the best of our knowledge, this is the first systematic structure-affinity relationship study on inhibition of CD22.
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Affiliation(s)
- Hajjaj H M Abdu-Allah
- Department of Applied Bio-organic Chemistry, The United Graduate School of Agricultural Sciences, Gifu University, Gifu 501-1193, Japan
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Toda M, Akita K, Inoue M, Taketani S, Nakada H. Down-modulation of B cell signal transduction by ligation of mucins to CD22. Biochem Biophys Res Commun 2008; 372:45-50. [PMID: 18474217 DOI: 10.1016/j.bbrc.2008.04.175] [Citation(s) in RCA: 199] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Accepted: 04/28/2008] [Indexed: 11/15/2022]
Abstract
Epithelial cancer cells secrete mucins carrying carbohydrate antigens such as a sialyl-Tn antigen into cancer tissues and/or the bloodstream, in which mucins may interact with CD22 (Siglec-2). Mucins isolated from colon cancer cells and bovine submaxillary mucins bound to CD22 cDNA transfectants and a human B cell line, Daudi cell, and the binding of soluble recombinant CD22 to the mucins was confirmed by means of a plate assay. The binding specificity was demonstrated by the fact that the mucins bound to the recombinant CD22 with an intact ectodomain but not to that with a mutated ectodomain. Daudi cells were stimulated with anti-IgM F(ab')(2) in the presence or absence of mucins. Ligation of mucins to CD22 decreased the phosphorylation of CD22 and SHP-1 recruitment, and the phosphorylation of ERK-1/2 prominently. The in vivo effect of mucins on splenic B cells in the tumor-bearing state was investigated using mucin-producing (TA3-Ha) and non-producing (TA3-St) mammary adenocarcinoma-bearing mice. When fluorescence-labeled epiglycanins were administered to normal mice, a portion of them was taken up by the spleen and became associated with splenic B cells. We found that splenic B cells were reduced in TA3-Ha-bearing mice but not in TA3-St-bearing ones. These results suggest that in the tumor-bearing state a portion of the mucins in the bloodstream was taken up by the spleen and ligated to CD22 expressed on splenic B cells, which may have led to down-regulation of signal transduction.
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Affiliation(s)
- Munetoyo Toda
- Department of Biotechnology, Faculty of Engineering, Kyoto Sangyo University, Kamigamo-Motoyama, Kita-ku, Kyoto 603-8555, Japan
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Onodera T, Poe JC, Tedder TF, Tsubata T. CD22 regulates time course of both B cell division and antibody response. THE JOURNAL OF IMMUNOLOGY 2008; 180:907-13. [PMID: 18178830 DOI: 10.4049/jimmunol.180.2.907] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Because pathogens induce infectious symptoms in a time-dependent manner, a rapid immune response is beneficial for defending hosts from pathogens, especially those inducing acute infectious diseases. However, it is largely unknown how the time course of immune responses is regulated. In this study, we demonstrate that B cells deficient in the inhibitory coreceptor CD22 undergo accelerated cell division after Ag stimulation, resulting in rapid generation of plasma cells and Ab production. This finding indicates that CD22 regulates the time course of B cell responses and suggests that CD22 is a good target to shorten the time required for Ab production, thereby augmenting host defense against acute infectious diseases as "universal vaccination."
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Affiliation(s)
- Taishi Onodera
- Laboratory of Immunology, School of Biomedical Science, Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Japan
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Zhu C, Sato M, Yanagisawa T, Fujimoto M, Adachi T, Tsubata T. Novel Binding Site for Src Homology 2-containing Protein-tyrosine Phosphatase-1 in CD22 Activated by B Lymphocyte Stimulation with Antigen. J Biol Chem 2008; 283:1653-1659. [DOI: 10.1074/jbc.m706584200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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Abstract
CD22 is an inhibitory coreceptor of the B-cell receptor (BCR), and plays a critical role in establishing signalling thresholds for B-cell activation. Like other coreceptors, the ability of CD22 to modulate B-cell signalling is critically dependent upon its proximity to the BCR, and this in turn is governed by the binding of its extracellular domain to alpha2,6-linked sialic acid ligands. Manipulation of CD22 ligand binding in various experimental settings has profound effects on B-cell signalling, but as yet there is no complete model for how ligand binding in vivo controls normal CD22 function. Several elegant studies have recently shed light on this issue, although the results appear to suggest two mutually exclusive models for the role of ligand binding; in either promoting or inhibiting, CD22 function. We shall therefore discuss these results in detail, and suggest possible approaches by which these conflicting experimental findings might be reconciled. We shall also consider a second important issue in CD22 biology, which relates to the role that defects in this receptor might play in mediating autoimmune disease. We review the current evidence for this, and discuss the importance of genetic background in modifying CD22 function and predisposition to autoimmunity.
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Affiliation(s)
- Jennifer A Walker
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke's Hospital, Cambridge CB2 0XY, United Kingdom.
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Bispecific anti-CD20/22 antibodies inhibit B-cell lymphoma proliferation by a unique mechanism of action. Blood 2007; 111:2211-9. [PMID: 18025153 DOI: 10.1182/blood-2007-08-110072] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Combination immunotherapy with anti-CD20 and anti-CD22 mAbs shows promising activity in non-Hodgkin lymphoma. Therefore, bispecific mAbs (bsAbs) were recombinantly constructed from veltuzumab (humanized anti-CD20) and epratuzumab (humanized anti-CD22) and evaluated in vitro and in vivo. While none of the parental mAbs alone or mixed had notable antiproliferative activity against Burkitt lymphoma cells when not cross-linked, the bsAbs [eg, anti-CD20 IgG-anti-CD22 (scFv)(2)] were inhibitory without cross-linking and synergistic with B-cell antigen (BCR)-mediated inhibition. The bsAbs demonstrated higher antibody-dependent cellulary cytoxicity (ADCC) activity than the parental mAbs, but not complement-dependent cytoxicity (CDC) of the parental CD20 mAb. Cross-linking both CD20 and CD22 with the bsAbs resulted in the prominent redistribution of not only CD20 but also CD22 and BCR into lipid rafts. Surprisingly, appreciable translocation of CD22 into lipid rafts was also observed after treatment with epratuzumab. Finally, the bsAbs inhibited Daudi lymphoma transplant growth, but showed a significant advantage over the parental anti-CD20 mAb only at the highest dose tested. These results suggest that recombinantly fused, complementary, bispecific, anti-CD20/22 antibodies exhibit functional features distinct from their parental antibodies, perhaps representing new candidate therapeutic molecules.
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