1
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Choi J, Ceribelli M, Phelan JD, Häupl B, Huang DW, Wright GW, Hsiao T, Morris V, Ciccarese F, Wang B, Corcoran S, Scheich S, Yu X, Xu W, Yang Y, Zhao H, Zhou J, Zhang G, Muppidi J, Inghirami GG, Oellerich T, Wilson WH, Thomas CJ, Staudt LM. Molecular targets of glucocorticoids that elucidate their therapeutic efficacy in aggressive lymphomas. Cancer Cell 2024; 42:833-849.e12. [PMID: 38701792 DOI: 10.1016/j.ccell.2024.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 03/29/2024] [Accepted: 04/09/2024] [Indexed: 05/05/2024]
Abstract
Glucocorticoids have been used for decades to treat lymphomas without an established mechanism of action. Using functional genomic, proteomic, and chemical screens, we discover that glucocorticoids inhibit oncogenic signaling by the B cell receptor (BCR), a recurrent feature of aggressive B cell malignancies, including diffuse large B cell lymphoma and Burkitt lymphoma. Glucocorticoids induce the glucocorticoid receptor (GR) to directly transactivate genes encoding negative regulators of BCR stability (LAPTM5; KLHL14) and the PI3 kinase pathway (INPP5D; DDIT4). GR directly represses transcription of CSK, a kinase that limits the activity of BCR-proximal Src-family kinases. CSK inhibition attenuates the constitutive BCR signaling of lymphomas by hyperactivating Src-family kinases, triggering their ubiquitination and degradation. With the knowledge that glucocorticoids disable oncogenic BCR signaling, they can now be deployed rationally to treat BCR-dependent aggressive lymphomas and used to construct mechanistically sound combination regimens with inhibitors of BTK, PI3 kinase, BCL2, and CSK.
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MESH Headings
- Humans
- Glucocorticoids/pharmacology
- Receptors, Antigen, B-Cell/metabolism
- Animals
- Signal Transduction/drug effects
- Receptors, Glucocorticoid/metabolism
- Mice
- Cell Line, Tumor
- Lymphoma, Large B-Cell, Diffuse/drug therapy
- Lymphoma, Large B-Cell, Diffuse/genetics
- Lymphoma, Large B-Cell, Diffuse/metabolism
- Burkitt Lymphoma/drug therapy
- Burkitt Lymphoma/genetics
- Burkitt Lymphoma/metabolism
- Burkitt Lymphoma/pathology
- Molecular Targeted Therapy/methods
- Phosphatidylinositol 3-Kinases/metabolism
- src-Family Kinases/metabolism
- Gene Expression Regulation, Neoplastic/drug effects
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Affiliation(s)
- Jaewoo Choi
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Michele Ceribelli
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD, USA
| | - James D Phelan
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Björn Häupl
- Department of Medicine II, Hematology/Oncology, Goethe University, Frankfurt, Germany; German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, 60528 Frankfurt am Main, Germany
| | - Da Wei Huang
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - George W Wright
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Tony Hsiao
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Vivian Morris
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Francesco Ciccarese
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA; Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCCS, via Gattamelata 64, 35128 Padova, Italy
| | - Boya Wang
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Sean Corcoran
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Sebastian Scheich
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA; Department of Medicine II, Hematology/Oncology, Goethe University, Frankfurt, Germany; German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, 60528 Frankfurt am Main, Germany; University Cancer Center (UCT) Frankfurt, University Hospital, Goethe University, 60590 Frankfurt am Main, Germany; Frankfurt Cancer Institute, Goethe University, 60596 Frankfurt am Main, Germany
| | - Xin Yu
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Weihong Xu
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yandan Yang
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Hong Zhao
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Joyce Zhou
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Grace Zhang
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jagan Muppidi
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Giorgio G Inghirami
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA
| | - Thomas Oellerich
- Department of Medicine II, Hematology/Oncology, Goethe University, Frankfurt, Germany; German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, 60528 Frankfurt am Main, Germany
| | - Wyndham H Wilson
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Craig J Thomas
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA; Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD, USA
| | - Louis M Staudt
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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2
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Corcoran SR, Phelan JD, Choi J, Shevchenko G, Fenner RE, Yu X, Scheich S, Hsiao T, Morris VM, Papachristou EK, Kishore K, D'Santos CS, Ji Y, Pittaluga S, Wright GW, Urlaub H, Pan KT, Oellerich T, Muppidi J, Hodson DJ, Staudt LM. Molecular Determinants of Sensitivity to Polatuzumab Vedotin in Diffuse Large B Cell Lymphoma. Cancer Discov 2024:745052. [PMID: 38683128 DOI: 10.1158/2159-8290.cd-23-0802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Revised: 03/12/2024] [Accepted: 04/23/2024] [Indexed: 05/01/2024]
Abstract
Polatuzumab Vedotin (Pola-V) is an antibody-drug conjugate directed to the CD79B subunit of the B cell receptor (BCR). When combined with conventional immunochemotherapy, Pola-V improves outcomes in DLBCL. To identify determinants of Pola-V sensitivity, we used CRISPR-Cas9 screening for genes that modulated Pola-V toxicity for lymphomas or the surface expression of its target, CD79B. Our results reveal the striking impact of CD79B glycosylation on Pola-V epitope availability on the lymphoma cell surface and on Pola-V toxicity. Genetic, pharmacological, and enzymatic approaches that remove sialic acid from N-linked glycans enhanced lymphoma killing by Pola-V. Pola-V toxicity was also modulated by KLHL6, an E3 ubiquitin ligase that is recurrently inactivated in germinal center derived lymphomas. We reveal how KLHL6 targets CD79B for degradation in normal and malignant germinal center B cells, thereby determining expression of the surface BCR complex. Our findings suggest precision medicine strategies to optimize Pola-V as a lymphoma therapeutic.
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Affiliation(s)
| | | | - Jaewoo Choi
- National Cancer Institute, Bethesda, United States
| | | | | | - Xin Yu
- National Cancer Institute, Bethesa, MD, United States
| | | | - Tony Hsiao
- National Institutes of Health, United States
| | | | | | - Kamal Kishore
- Cancer Research UK Cambridge Institute, United Kingdom
| | - Clive S D'Santos
- Cancer Research UK Cambridge Research Institute, Cambridge, United Kingdom
| | - Yanlong Ji
- Max-Planck-Institute for Multidisciplinary Sciences, Goettingen, Germany
| | | | | | - Henning Urlaub
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Kuan-Ting Pan
- University Hospital Frankfurt, Frankfurt am Main, Germany
| | | | - Jagan Muppidi
- National Institutes of Health, Bethesda, MD, United States
| | - Daniel J Hodson
- Wellcome/MRC Cambridge Stem Cell Institute, Cambridge, United Kingdom
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3
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Radtke AJ, Postovalova E, Varlamova A, Bagaev A, Sorokina M, Kudryashova O, Meerson M, Polyakova M, Galkin I, Svekolkin V, Isaev S, Wiebe D, Sharun A, Sarachakov A, Perelman G, Lozinsky Y, Yaniv Z, Lowekamp BC, Speranza E, Yao L, Pittaluga S, Shaffer AL, Jonigk D, Phelan JD, Davies-Hill T, Huang DW, Ovcharov P, Nomie K, Nuzhdina E, Kotlov N, Ataullakhanov R, Fowler N, Kelly M, Muppidi J, Davis JL, Hernandez JM, Wilson WH, Jaffe ES, Staudt LM, Roschewski M, Germain RN. Multi-omic profiling of follicular lymphoma reveals changes in tissue architecture and enhanced stromal remodeling in high-risk patients. Cancer Cell 2024; 42:444-463.e10. [PMID: 38428410 PMCID: PMC10966827 DOI: 10.1016/j.ccell.2024.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 12/04/2023] [Accepted: 02/05/2024] [Indexed: 03/03/2024]
Abstract
Follicular lymphoma (FL) is a generally incurable malignancy that evolves from developmentally blocked germinal center (GC) B cells. To promote survival and immune escape, tumor B cells undergo significant genetic changes and extensively remodel the lymphoid microenvironment. Dynamic interactions between tumor B cells and the tumor microenvironment (TME) are hypothesized to contribute to the broad spectrum of clinical behaviors observed among FL patients. Despite the urgent need, existing clinical tools do not reliably predict disease behavior. Using a multi-modal strategy, we examined cell-intrinsic and -extrinsic factors governing progression and therapeutic outcomes in FL patients enrolled onto a prospective clinical trial. By leveraging the strengths of each platform, we identify several tumor-specific features and microenvironmental patterns enriched in individuals who experience early relapse, the most high-risk FL patients. These features include stromal desmoplasia and changes to the follicular growth pattern present 20 months before first progression and first relapse.
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Affiliation(s)
- Andrea J Radtke
- Lymphocyte Biology Section and Center for Advanced Tissue Imaging, Laboratory of Immune System Biology, NIAID, NIH, Bethesda, MD 20892, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Ziv Yaniv
- Bioinformatics and Computational Bioscience Branch, NIAID, NIH, Bethesda, MD 20892, USA
| | - Bradley C Lowekamp
- Bioinformatics and Computational Bioscience Branch, NIAID, NIH, Bethesda, MD 20892, USA
| | - Emily Speranza
- Lymphocyte Biology Section and Center for Advanced Tissue Imaging, Laboratory of Immune System Biology, NIAID, NIH, Bethesda, MD 20892, USA; Florida Research and Innovation Center, Cleveland Clinic Lerner Research Institute, Port Saint Lucie, FL 34987, USA
| | - Li Yao
- Li Yao Visuals, Rockville, MD 20855, USA
| | | | - Arthur L Shaffer
- Lymphoid Malignancies Branch, NCI, NIH, Bethesda, MD 20892, USA; Tumor Targeted Delivery, Heme Malignancy Target Discovery Group, AstraZeneca, Gaithersburg, MD 20878, USA
| | - Danny Jonigk
- Institute of Pathology, Aachen Medical University, RWTH Aachen, 52074 Aachen, Germany; German Center for Lung Research (DZL), Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), 30625 Hannover, Germany
| | - James D Phelan
- Lymphoid Malignancies Branch, NCI, NIH, Bethesda, MD 20892, USA
| | | | - Da Wei Huang
- Lymphoid Malignancies Branch, NCI, NIH, Bethesda, MD 20892, USA
| | | | | | | | | | | | | | - Michael Kelly
- CCR Single Analysis Facility, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Bethesda, MD 20892, USA
| | - Jagan Muppidi
- Lymphoid Malignancies Branch, NCI, NIH, Bethesda, MD 20892, USA
| | - Jeremy L Davis
- Surgical Oncology Program, Metastasis Biology Section, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Jonathan M Hernandez
- Surgical Oncology Program, Metastasis Biology Section, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | | | - Elaine S Jaffe
- Laboratory of Pathology, NCI, NIH, Bethesda, MD 20892, USA
| | - Louis M Staudt
- Lymphoid Malignancies Branch, NCI, NIH, Bethesda, MD 20892, USA
| | - Mark Roschewski
- Lymphoid Malignancies Branch, NCI, NIH, Bethesda, MD 20892, USA
| | - Ronald N Germain
- Lymphocyte Biology Section and Center for Advanced Tissue Imaging, Laboratory of Immune System Biology, NIAID, NIH, Bethesda, MD 20892, USA
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4
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Scheich S, Chen J, Liu J, Schnütgen F, Enssle JC, Ceribelli M, Thomas CJ, Choi J, Morris V, Hsiao T, Nguyen H, Wang B, Bolomsky A, Phelan JD, Corcoran S, Urlaub H, Young RM, Häupl B, Wright GW, Huang DW, Ji Y, Yu X, Xu W, Yang Y, Zhao H, Muppidi J, Pan KT, Oellerich T, Staudt LM. Targeting N-linked Glycosylation for the Therapy of Aggressive Lymphomas. Cancer Discov 2023; 13:1862-1883. [PMID: 37141112 PMCID: PMC10524254 DOI: 10.1158/2159-8290.cd-22-1401] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 03/21/2023] [Accepted: 05/02/2023] [Indexed: 05/05/2023]
Abstract
Diffuse large B-cell lymphoma (DLBCL) can be subdivided into the activated B-cell (ABC) and germinal center B cell-like (GCB) subtypes. Self-antigen engagement of B-cell receptors (BCR) in ABC tumors induces their clustering, thereby initiating chronic active signaling and activation of NF-κB and PI3 kinase. Constitutive BCR signaling is essential in some GCB tumors but primarily activates PI3 kinase. We devised genome-wide CRISPR-Cas9 screens to identify regulators of IRF4, a direct transcriptional target of NF-κB and an indicator of proximal BCR signaling in ABC DLBCL. Unexpectedly, inactivation of N-linked protein glycosylation by the oligosaccharyltransferase-B (OST-B) complex reduced IRF4 expression. OST-B inhibition of BCR glycosylation reduced BCR clustering and internalization while promoting its association with CD22, which attenuated PI3 kinase and NF-κB activation. By directly interfering with proximal BCR signaling, OST-B inactivation killed models of ABC and GCB DLBCL, supporting the development of selective OST-B inhibitors for the treatment of these aggressive cancers. SIGNIFICANCE DLBCL depends on constitutive BCR activation and signaling. There are currently no therapeutics that target the BCR directly and attenuate its pathologic signaling. Here, we unraveled a therapeutically exploitable, OST-B-dependent glycosylation pathway that drives BCR organization and proximal BCR signaling. This article is highlighted in the In This Issue feature, p. 1749.
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Affiliation(s)
- Sebastian Scheich
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jiji Chen
- Advanced Imaging and Microscopy Resource, National Institutes of Health, Bethesda, MD, USA
| | - Jiamin Liu
- Advanced Imaging and Microscopy Resource, National Institutes of Health, Bethesda, MD, USA
| | - Frank Schnütgen
- Department of Medicine, Hematology/Oncology, University Hospital Frankfurt, Goethe University, Frankfurt, Germany
- German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, and German Cancer Research Center (DKFZ), Heidelberg, Germany
- Frankfurt Cancer Institute, Goethe-University Frankfurt, Frankfurt/Main, Germany
| | - Julius C. Enssle
- Department of Medicine, Hematology/Oncology, University Hospital Frankfurt, Goethe University, Frankfurt, Germany
| | - Michele Ceribelli
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD, USA
| | - Craig J. Thomas
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD, USA
| | - Jaewoo Choi
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Vivian Morris
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
- Johns Hopkins University, Department of Biology, Baltimore, MD, 21218, USA
| | - Tony Hsiao
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Hang Nguyen
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Boya Wang
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Arnold Bolomsky
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - James D. Phelan
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Sean Corcoran
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
- Bioanalytics, Institute of Clinical Chemistry, University Medical Center Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - Ryan M. Young
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Björn Häupl
- Department of Medicine, Hematology/Oncology, University Hospital Frankfurt, Goethe University, Frankfurt, Germany
- German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, and German Cancer Research Center (DKFZ), Heidelberg, Germany
- Frankfurt Cancer Institute, Goethe-University Frankfurt, Frankfurt/Main, Germany
| | - George W. Wright
- Biometric Research Branch, Division of Cancer Diagnosis and Treatment, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Da Wei Huang
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yanlong Ji
- Department of Medicine, Hematology/Oncology, University Hospital Frankfurt, Goethe University, Frankfurt, Germany
- Bioanalytical Mass Spectrometry Group, Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
- Frankfurt Cancer Institute, Goethe-University Frankfurt, Frankfurt/Main, Germany
| | - Xin Yu
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Weihong Xu
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Yandan Yang
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Hong Zhao
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jagan Muppidi
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Kuan-Ting Pan
- Frankfurt Cancer Institute, Goethe-University Frankfurt, Frankfurt/Main, Germany
| | - Thomas Oellerich
- Department of Medicine, Hematology/Oncology, University Hospital Frankfurt, Goethe University, Frankfurt, Germany
- German Cancer Consortium (DKTK), Partner Site Frankfurt/Mainz, and German Cancer Research Center (DKFZ), Heidelberg, Germany
- Frankfurt Cancer Institute, Goethe-University Frankfurt, Frankfurt/Main, Germany
| | - Louis M. Staudt
- Lymphoid Malignancies Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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5
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Reboldi A, Raso F, Berthellete A, Sagadiev S, Moses S, Acharya M, Barton G, Muppidi J, Marshak-Rothstein A. IgA B cell receptor signaling protects from FasL counterselection during germinal center reaction in Peyer’s patches and shapes humoral mucosal response. The Journal of Immunology 2022. [DOI: 10.4049/jimmunol.208.supp.113.07] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Immunoglobulin A (IgA) is the main antibody isotype found in the intestine: deficiency in IgA alters microbiome composition, leads to increased susceptibility to enteric pathogens and reduces tissue response to oral vaccine. IgA can bind multiple unrelated bacterial taxa, but mechanistic insights into the generation of such cross-species reactivity are lacking. IgA+ B cells arise during germinal center (GC) reaction in Peyer’s patches: however, the role of IgA B cell receptor (BCR) in shaping the humoral response at the intestinal interface remains unknown.
Here we showed that GC B cells lacking IgA are rapidly outcompeted by IgA+ B cells during GC reaction in Peyer’s patches and they are unable to contribute to memory B cell and intestinal-homing plasma cell compartments. IgA BCR did not impact cell proliferation in dark zone, and ectopic Bcl-2 expression was unable to rescue IgA-deficient GC B cells in mixed bone marrow chimeras. In contrast, IgA-deficient GC B cells underwent increased apoptosis in the light zone. In line with these findings, we observed that IgA BCR mediated faster and stronger intracellular Ca2+ signaling and led to increase BCR-dependent phosphorylation events. Mechanistically, IgA BCR signaling conferred resistance to Fas ligand (FasL)-dependent cell death in vitro, and genetic inhibition of Fas-FasL pathway restored IgA-deficient B cell fitness during GC reaction in vivo.
Thus, our results showed that IgA-expressing GC B cells are protected from FasL counterselection in the light zone via enhanced BCR intracellular signaling. This process might allow low affinity B cell clones to participate to the GC reaction and assure a comprehensive humoral response to poorly immunogenic commensal species.
Supported by grants from NIH (T32 AI132152, T32 AI007349 and R01 AI155727-02)
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Affiliation(s)
- Andrea Reboldi
- 1Department of Pathology, Univ. of Massachusetts Med. Sch
| | - Fiona Raso
- 1Department of Pathology, Univ. of Massachusetts Med. Sch
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6
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Affiliation(s)
- Jagan Muppidi
- National Institute of Arthritis and Musculoskeletal and Skin Diseases Bethesda Maryland
| | - Melissa Porter
- National Institute of Arthritis and Musculoskeletal and Skin Diseases Bethesda Maryland
| | - Richard M. Siegel
- National Institute of Arthritis and Musculoskeletal and Skin Diseases Bethesda Maryland
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7
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Abstract
In recent years, it has become clear that self-nonself discrimination by the immune system is driven not so much by the specificities of the antigen receptors themselves, but by ligand-receptor systems that sense the presence of foreign pathogens (toll-like receptors) and those that regulate the balance between cellular proliferation and programmed cell death (tumor necrosis factor [TNF] family ligands and receptors). Interestingly, these two receptor families share a number of common signaling pathways, mediated by the cytoplasmic proteins containing death domains and TRAF domains, which trigger the complementary processes of programmed cell death and inflammation. Both humans and mice with genetic defects in the TNF-receptor family member Fas accumulate abnormal lymphocytes and develop systemic autoimmunity. These findings highlighted the importance of this TNF-receptor family member in the homeostasis of the immune system. In particular, the Fas receptor has been shown to be important in immunoreceptor-mediated apoptosis of activated T and B lymphocytes. Six members of the TNF-receptor superfamily share a common signaling domain with Fas, termed the death domain, that directly links these receptors to the apoptotic machinery of the cell, and, collectively, these receptors have been designated as "death receptors."We are currently investigating a number of important unresolved issues in this field, including: (1). how susceptibility to apoptosis through death receptors is regulated, (2). how Fas and related death receptors function in the maintenance of self-tolerance and homeostasis in the major cell types of the immune system, and (3). recently described nonapoptotic lymphocyte activation signals that use components of death receptor signaling.
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Affiliation(s)
- Richard M Siegel
- Immunoregulation Section, Autoimmunity Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institute of Health, Bethesda, MD 20892, USA.
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