1
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McCaleb MR, Miranda AM, Khammash HA, Torres RM, Pelanda R. Regulation of Foxo1 expression is critical for central B cell tolerance and allelic exclusion. Cell Rep 2024; 43:114283. [PMID: 38796853 PMCID: PMC11246624 DOI: 10.1016/j.celrep.2024.114283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 05/03/2024] [Accepted: 05/10/2024] [Indexed: 05/29/2024] Open
Abstract
Resolving the molecular mechanisms of central B cell tolerance might unveil strategies that prevent autoimmunity. Here, using a mouse model of central B cell tolerance in which Forkhead box protein O1 (Foxo1) is either deleted or over-expressed in B cells, we show that deleting Foxo1 blocks receptor editing, curtails clonal deletion, and decreases CXCR4 expression, allowing high-avidity autoreactive B cells to emigrate to the periphery whereby they mature but remain anergic and short lived. Conversely, expression of degradation-resistant Foxo1 promotes receptor editing in the absence of self-antigen but leads to allelic inclusion. Foxo1 over-expression also restores tolerance in autoreactive B cells harboring active PI3K, revealing opposing roles of Foxo1 and PI3K in B cell selection. Overall, we show that the transcription factor Foxo1 is a major gatekeeper of central B cell tolerance and that PI3K drives positive selection of immature B cells and establishes allelic exclusion by suppressing Foxo1.
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Affiliation(s)
- Megan R McCaleb
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Anjelica M Miranda
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Hadeel A Khammash
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Raul M Torres
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Roberta Pelanda
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA.
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2
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Florova M, Abreu-Mota T, Paesen GC, Beetschen AS, Cornille K, Marx AF, Narr K, Sahin M, Dimitrova M, Swarnalekha N, Beil-Wagner J, Savic N, Pelczar P, Buch T, King CG, Bowden TA, Pinschewer DD. Central tolerance shapes the neutralizing B cell repertoire against a persisting virus in its natural host. Proc Natl Acad Sci U S A 2024; 121:e2318657121. [PMID: 38446855 PMCID: PMC10945855 DOI: 10.1073/pnas.2318657121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 01/29/2024] [Indexed: 03/08/2024] Open
Abstract
Viral mimicry of host cell structures has been postulated to curtail the B cell receptor (BCR) repertoire against persisting viruses through tolerance mechanisms. This concept awaits, however, experimental testing in a setting of natural virus-host relationship. We engineered mouse models expressing a monoclonal BCR specific for the envelope glycoprotein of lymphocytic choriomeningitis virus (LCMV), a naturally persisting mouse pathogen. When the heavy chain of the LCMV-neutralizing antibody KL25 was paired with its unmutated ancestor light chain, most B cells underwent receptor editing, a behavior reminiscent of autoreactive clones. In contrast, monoclonal B cells expressing the same heavy chain in conjunction with the hypermutated KL25 light chain did not undergo receptor editing but exhibited low levels of surface IgM, suggesting that light chain hypermutation had lessened KL25 autoreactivity. Upon viral challenge, these IgMlow cells were not anergic but up-regulated IgM, participated in germinal center reactions, produced antiviral antibodies, and underwent immunoglobulin class switch as well as further affinity maturation. These studies on a persisting virus in its natural host species suggest that central tolerance mechanisms prune the protective antiviral B cell repertoire.
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Affiliation(s)
- Marianna Florova
- Division of Experimental Virology, Department of Biomedicine, University of Basel, Basel4009, Switzerland
| | - Tiago Abreu-Mota
- Division of Experimental Virology, Department of Biomedicine, University of Basel, Basel4009, Switzerland
| | - Guido C. Paesen
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom
| | - Anna Sophia Beetschen
- Division of Experimental Virology, Department of Biomedicine, University of Basel, Basel4009, Switzerland
| | - Karen Cornille
- Division of Experimental Virology, Department of Biomedicine, University of Basel, Basel4009, Switzerland
| | - Anna-Friederike Marx
- Division of Experimental Virology, Department of Biomedicine, University of Basel, Basel4009, Switzerland
| | - Kerstin Narr
- Division of Experimental Virology, Department of Biomedicine, University of Basel, Basel4009, Switzerland
| | - Mehmet Sahin
- Division of Experimental Virology, Department of Biomedicine, University of Basel, Basel4009, Switzerland
| | - Mirela Dimitrova
- Division of Experimental Virology, Department of Biomedicine, University of Basel, Basel4009, Switzerland
| | - Nivedya Swarnalekha
- Department of Biomedicine, Immune Cell Biology Laboratory, University Hospital Basel, Basel4031, Switzerland
| | - Jane Beil-Wagner
- Institute of Laboratory Animal Science, University of Zurich, Zurich8093, Switzerland
| | - Natasa Savic
- ETH Phenomics Center, ETH Zürich, Zürich8093, Switzerland
| | - Pawel Pelczar
- Center for Transgenic Models, University of Basel, Basel4001, Switzerland
| | - Thorsten Buch
- Institute of Laboratory Animal Science, University of Zurich, Zurich8093, Switzerland
| | - Carolyn G. King
- Department of Biomedicine, Immune Cell Biology Laboratory, University Hospital Basel, Basel4031, Switzerland
| | - Thomas A. Bowden
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, United Kingdom
| | - Daniel D. Pinschewer
- Division of Experimental Virology, Department of Biomedicine, University of Basel, Basel4009, Switzerland
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3
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McCaleb MR, Miranda AM, Ratliff KC, Torres RM, Pelanda R. CD19 Is Internalized Together with IgM in Proportion to B Cell Receptor Stimulation and Is Modulated by Phosphatidylinositol 3-Kinase in Bone Marrow Immature B Cells. Immunohorizons 2023; 7:49-63. [PMID: 36637517 PMCID: PMC10074640 DOI: 10.4049/immunohorizons.2200092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 12/16/2022] [Indexed: 01/14/2023] Open
Abstract
Newly generated immature B cells that bind self-antigen with high avidity arrest in differentiation and undergo central tolerance via receptor editing and clonal deletion. These autoreactive immature B cells also express low surface levels of the coreceptor CD19, a key activator of the PI3K pathway. Signals emanating from both CD19 and PI3K are known to be critical for attenuating receptor editing and selecting immature B cells into the periphery. However, the mechanisms that modulate CD19 expression at this stage of B cell development have not yet been resolved. Using in vivo and in vitro models, we demonstrate that Cd19 de novo gene transcription and translation do not significantly contribute to the differences in CD19 surface expression in mouse autoreactive and nonautoreactive immature B cells. Instead, CD19 downregulation is induced by BCR stimulation in proportion to BCR engagement, and the remaining surface IgM and CD19 molecules promote intracellular PI3K-AKT activity in proportion to their level of expression. The internalized CD19 is degraded with IgM by the lysosome, but inhibiting lysosome-mediated protein degradation only slightly improves surface CD19. In fact, CD19 is restored only upon Ag removal. Our data also reveal that the PI3K-AKT pathway positively modulates CD19 surface expression in immature B cells via a mechanism that is independent of inhibition of FOXO1 and its role on Cd19 gene transcription while is dependent on mTORC1.
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Affiliation(s)
- Megan R. McCaleb
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO; and
| | - Anjelica M. Miranda
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO; and
| | - Kaysie C. Ratliff
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO; and
| | - Raul M. Torres
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO; and
- Department of Immunology and Genomic Medicine, National Jewish Health, Denver, CO
| | - Roberta Pelanda
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO; and
- Department of Immunology and Genomic Medicine, National Jewish Health, Denver, CO
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4
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Okoreeh MK, Kennedy DE, Emmanuel AO, Veselits M, Moshin A, Ladd RH, Erickson S, McLean KC, Madrigal B, Nemazee D, Maienschein-Cline M, Mandal M, Clark MR. Asymmetrical forward and reverse developmental trajectories determine molecular programs of B cell antigen receptor editing. Sci Immunol 2022; 7:eabm1664. [PMID: 35930652 PMCID: PMC9636592 DOI: 10.1126/sciimmunol.abm1664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
During B lymphopoiesis, B cell progenitors progress through alternating and mutually exclusive stages of clonal expansion and immunoglobulin (Ig) gene rearrangements. Great diversity is generated through the stochastic recombination of Ig gene segments encoding heavy and light chain variable domains. However, this commonly generates autoreactivity. Receptor editing is the predominant tolerance mechanism for self-reactive B cells in the bone marrow (BM). B cell receptor editing rescues autoreactive B cells from negative selection through renewed light chain recombination first at Igκ then Igλ loci. Receptor editing depends on BM microenvironment cues and key transcription factors such as NF-κB, FOXO, and E2A. The specific BM factor required for receptor editing is unknown. Furthermore, how transcription factors coordinate these developmental programs to promote usage of the λ chain remains poorly defined. Therefore, we used two mouse models that recapitulate pathways by which Igλ light chain-positive B cells develop. The first has deleted J kappa (Jκ) genes and hence models Igλ expression resulting from failed Igκ recombination (Igκdel). The second models autoreactivity by ubiquitous expression of a single-chain chimeric anti-Igκ antibody (κ-mac). Here, we demonstrated that autoreactive B cells transit asymmetric forward and reverse developmental trajectories. This imparted a unique epigenetic landscape on small pre-B cells, which opened chromatin to transcription factors essential for Igλ recombination. The consequences of this asymmetric developmental path were both amplified and complemented by CXCR4 signaling. These findings reveal how intrinsic molecular programs integrate with extrinsic signals to drive receptor editing.
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Affiliation(s)
- Michael K. Okoreeh
- Department of Medicine, Section of Rheumatology, University of Chicago, Chicago, IL, 60637, USA
- Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, 60637, USA
- Growth, Development, Disabilities Training program (GDDTP), Pritzker School of Medicine, University of Chicago, IL, 60637, USA
| | - Domenick E. Kennedy
- Department of Medicine, Section of Rheumatology, University of Chicago, Chicago, IL, 60637, USA
- Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, 60637, USA
- Present Address: Drug Discovery Science and Technology, Discovery Platform Technologies, Chemical Biology and Emerging Therapeutics, AbbVie, North Chicago, IL, United States
| | - Akinola Olumide Emmanuel
- Department of Medicine, Section of Rheumatology, University of Chicago, Chicago, IL, 60637, USA
- Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, 60637, USA
| | - Margaret Veselits
- Department of Medicine, Section of Rheumatology, University of Chicago, Chicago, IL, 60637, USA
- Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, 60637, USA
| | - Azam Moshin
- Department of Medicine, Section of Rheumatology, University of Chicago, Chicago, IL, 60637, USA
- Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, 60637, USA
| | - Robert H. Ladd
- Cytometry and Antibody Technologies Facility, University of Chicago, Chicago, IL, 60637, USA
| | - Steven Erickson
- Department of Pathology, University of Chicago, Chicago, IL, 60637, USA
| | - Kaitlin C. McLean
- Department of Medicine, Section of Rheumatology, University of Chicago, Chicago, IL, 60637, USA
- Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, 60637, USA
| | - Brianna Madrigal
- Department of Medicine, Section of Rheumatology, University of Chicago, Chicago, IL, 60637, USA
| | - David Nemazee
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | | | - Malay Mandal
- Department of Medicine, Section of Rheumatology, University of Chicago, Chicago, IL, 60637, USA
- Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, 60637, USA
| | - Marcus R. Clark
- Department of Medicine, Section of Rheumatology, University of Chicago, Chicago, IL, 60637, USA
- Gwen Knapp Center for Lupus and Immunology Research, University of Chicago, Chicago, IL, 60637, USA
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5
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Renna V, Surova E, Khadour A, Datta M, Amendt T, Hobeika E, Jumaa H. Defective Allelic Exclusion by IgD in the Absence of Autoantigen. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:293-302. [PMID: 34930782 DOI: 10.4049/jimmunol.2100726] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 11/02/2021] [Indexed: 11/19/2022]
Abstract
A considerable proportion of peripheral B cells is autoreactive, and it is unclear how the activation of such potentially harmful cells is regulated. In this study, we show that the different activation thresholds or IgM and IgD BCRs adjust B cell activation to the diverse requirements during development. We rely on the autoreactive 3-83 model BCR to generate and analyze mice expressing exclusively autoreactive IgD BCRs on two different backgrounds that determine two stages of autoreactivity, depending on the presence or absence of the cognate Ag. By comparing these models with IgM-expressing control mice, we found that, compared with IgM, IgD has a higher activation threshold in vivo, as it requires autoantigen to enable normal B cell development, including allelic exclusion. Our data indicate that IgM provides the high sensitivity required during early developmental stages to trigger editing of any autoreactive specificities, including those enabling weak interaction with autoantigen. In contrast, IgD has the unique ability to neglect weakly interacting autoantigens while retaining reactivity to higher-affinity Ag. This IgD function enables mature B cells to ignore autoantigens while remaining able to efficiently respond to foreign threats.
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Affiliation(s)
- Valerio Renna
- Institute of Immunology, Ulm University Medical Center, Ulm, Germany
| | - Elena Surova
- Spemann Graduate School of Biology and Medicine, Albert Ludwig University of Freiburg, Freiburg, Germany; and.,Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Ahmad Khadour
- Institute of Immunology, Ulm University Medical Center, Ulm, Germany
| | - Moumita Datta
- Institute of Immunology, Ulm University Medical Center, Ulm, Germany
| | - Timm Amendt
- Institute of Immunology, Ulm University Medical Center, Ulm, Germany
| | - Elias Hobeika
- Institute of Immunology, Ulm University Medical Center, Ulm, Germany
| | - Hassan Jumaa
- Institute of Immunology, Ulm University Medical Center, Ulm, Germany;
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6
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Pelanda R, Greaves SA, Alves da Costa T, Cedrone LM, Campbell ML, Torres RM. B-cell intrinsic and extrinsic signals that regulate central tolerance of mouse and human B cells. Immunol Rev 2022; 307:12-26. [PMID: 34997597 PMCID: PMC8986553 DOI: 10.1111/imr.13062] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 12/28/2021] [Indexed: 12/20/2022]
Abstract
The random recombination of immunoglobulin V(D)J gene segments produces unique IgM antibodies that serve as the antigen receptor for each developing B cell. Hence, the newly formed B cell repertoire is comprised of a variety of specificities that display a range of reactivity with self-antigens. Newly generated IgM+ immature B cells that are non-autoreactive or that bind self-antigen with low avidity are licensed to leave the bone marrow with their intact antigen receptor and to travel via the blood to the peripheral lymphoid tissue for further selection and maturation. In contrast, clones with medium to high avidity for self-antigen remain within the marrow and undergo central tolerance, a process that revises their antigen receptor or eliminates the autoreactive B cell altogether. Thus, central B cell tolerance is critical for reducing the autoreactive capacity and avidity for self-antigen of our circulating B cell repertoire. Bone marrow cultures and mouse models have been instrumental for understanding the mechanisms that regulate the selection of bone marrow B cells. Here, we review recent studies that have shed new light on the contribution of the ERK, PI3K, and CXCR4 signaling pathways in the selection of mouse and human immature B cells that either bind or do not bind self-antigen.
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Affiliation(s)
- Roberta Pelanda
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA.,Department of Immunology and Genomic Medicine, National Jewish Health, Denver, Colorado, USA
| | - Sarah A Greaves
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Thiago Alves da Costa
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Lena M Cedrone
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Margaret L Campbell
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Raul M Torres
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA.,Department of Immunology and Genomic Medicine, National Jewish Health, Denver, Colorado, USA
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7
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B Cells in Primary Membranous Nephropathy: Escape from Immune Tolerance and Implications for Patient Management. Int J Mol Sci 2021; 22:ijms222413560. [PMID: 34948358 PMCID: PMC8708506 DOI: 10.3390/ijms222413560] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 12/03/2022] Open
Abstract
Membranous nephropathy (MN) is an important cause of nephrotic syndrome and chronic kidney disease (CKD) in adults. The pathogenic significance of B cells in MN is increasingly recognized, especially following the discovery of various autoantibodies that target specific podocytic antigens and the promising treatment responses seen with B cell depleting therapies. The presence of autoreactive B cells and autoantibodies that bind to antigens on podocyte surfaces are characteristic features of MN, and are the result of breaches in central and peripheral tolerance of B lymphocytes. These perturbations in B cell tolerance include altered B lymphocyte subsets, dysregulation of genes that govern immunoglobulin production, aberrant somatic hypermutation and co-stimulatory signalling, abnormal expression of B cell-related cytokines, and increased B cell infiltrates and organized tertiary lymphoid structures within the kidneys. An understanding of the role of B cell tolerance and homeostasis may have important implications for patient management in MN, as conventional immunosuppressive treatments and novel B cell-targeted therapies show distinct effects on proliferation, differentiation and reconstitution in different B cell subsets. Circulating B lymphocytes and related cytokines may serve as potential biomarkers for treatment selection, monitoring of therapeutic response and prediction of disease relapse. These recent advances in the understanding of B cell tolerance in MN have provided greater insight into its immunopathogenesis and potential novel strategies for disease monitoring and treatment.
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8
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Ren A, Sun J, Yin W, Westerberg LS, Miller H, Lee P, Candotti F, Guan F, Lei J, Gong Q, Chen Y, Liu C. Signaling networks in B cell development and related therapeutic strategies. J Leukoc Biol 2021; 111:877-891. [PMID: 34528729 DOI: 10.1002/jlb.2ru0221-088rrr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
B cells are essential for Ab production during humoral immune responses. From decades of B cell research, there is now a detailed understanding of B cell subsets, development, functions, and most importantly, signaling pathways. The complicated pathways in B cells and their interactions with each other are stage-dependent, varying with surface marker expression during B cell development. With the increasing understanding of B cell development and signaling pathways, the mechanisms underlying B cell related diseases are being unraveled as well, making it possible to provide more precise and effective treatments. In this review, we describe several essential and recently discovered signaling pathways in B cell development and take a look at newly developed therapeutic strategies targeted at B cell signaling.
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Affiliation(s)
- Anwen Ren
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jianxuan Sun
- Department and Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Yin
- Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Lisa S Westerberg
- Department of Microbiology Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Heather Miller
- The Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Pamela Lee
- Department of Paediatrics and Adolescent Medicine, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Fabio Candotti
- Division of Immunology and Allergy, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Fei Guan
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jiahui Lei
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Quan Gong
- Department of Immunology, School of Medicine, Yangtze University, Jingzhou, China.,Clinical Molecular Immunology Center, School of Medicine, Yangtze University, Jingzhou, China
| | - Yan Chen
- The Second Department of Pediatrics, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou, China
| | - Chaohong Liu
- Department of Pathogen Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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9
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Vanhee S, Åkerstrand H, Kristiansen TA, Datta S, Montano G, Vergani S, Lang S, Ungerbäck J, Doyle A, Olsson K, Beneventi G, Jensen CT, Bellodi C, Soneji S, Sigvardsson M, Gyllenbäck EJ, Yuan J. Lin28b controls a neonatal to adult switch in B cell positive selection. Sci Immunol 2019; 4:4/39/eaax4453. [DOI: 10.1126/sciimmunol.aax4453] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 08/27/2019] [Indexed: 12/21/2022]
Abstract
The ability of B-1 cells to become positively selected into the mature B cell pool, despite being weakly self-reactive, has puzzled the field since its initial discovery. Here, we explore changes in B cell positive selection as a function of developmental time by exploiting a link between CD5 surface levels and the natural occurrence of self-reactive B cell receptors (BCRs) in BCR wild-type mice. We show that the heterochronic RNA binding protein Lin28b potentiates a neonatal mode of B cell selection characterized by enhanced overall positive selection in general and the developmental progression of CD5+immature B cells in particular. Lin28b achieves this by amplifying the CD19/PI3K/c-Myc positive feedback loop, and ectopic Lin28b expression restores both positive selection and mature B cell numbers in CD19−/−adult mice. Thus, the temporally restricted expression ofLin28brelaxes the rules for B cell selection during ontogeny by modulating tonic signaling. We propose that this neonatal mode of B cell selection represents a cell-intrinsic cue to accelerate the de novo establishment of the adaptive immune system and incorporate a layer of natural antibody-mediated immunity throughout life.
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10
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Burnett DL, Reed JH, Christ D, Goodnow CC. Clonal redemption and clonal anergy as mechanisms to balance B cell tolerance and immunity. Immunol Rev 2019; 292:61-75. [DOI: 10.1111/imr.12808] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 09/10/2019] [Accepted: 09/13/2019] [Indexed: 12/19/2022]
Affiliation(s)
- Deborah L. Burnett
- Garvan Institute of Medical Research Darlinghurst NSW Australia
- St Vincent's Clinical School UNSW Sydney Darlinghurst NSW Australia
| | - Joanne H. Reed
- Garvan Institute of Medical Research Darlinghurst NSW Australia
- St Vincent's Clinical School UNSW Sydney Darlinghurst NSW Australia
| | - Daniel Christ
- Garvan Institute of Medical Research Darlinghurst NSW Australia
- St Vincent's Clinical School UNSW Sydney Darlinghurst NSW Australia
| | - Christopher C. Goodnow
- Garvan Institute of Medical Research Darlinghurst NSW Australia
- St Vincent's Clinical School UNSW Sydney Darlinghurst NSW Australia
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11
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Greaves SA, Peterson JN, Strauch P, Torres RM, Pelanda R. Active PI3K abrogates central tolerance in high-avidity autoreactive B cells. J Exp Med 2019; 216:1135-1153. [PMID: 30948496 PMCID: PMC6504226 DOI: 10.1084/jem.20181652] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 01/23/2019] [Accepted: 03/22/2019] [Indexed: 01/02/2023] Open
Abstract
High-avidity autoreactive B cells are typically removed by central tolerance mechanisms in the bone marrow. Greaves et al. demonstrate that B cell–intrinsic expression of active PI3Kα prevents central tolerance and effectively promotes differentiation and activation of high-avidity autoreactive B cells in the periphery. Autoreactive B cells that bind self-antigen with high avidity in the bone marrow undergo mechanisms of central tolerance that prevent their entry into the peripheral B cell population. These mechanisms are breached in many autoimmune patients, increasing their risk of B cell–mediated autoimmune diseases. Resolving the molecular pathways that can break central B cell tolerance could therefore provide avenues to diminish autoimmunity. Here, we show that B cell–intrinsic expression of a constitutively active form of PI3K-P110α by high-avidity autoreactive B cells of mice completely abrogates central B cell tolerance and further promotes these cells to escape from the bone marrow, differentiate in peripheral tissue, and undergo activation in response to self-antigen. Upon stimulation with T cell help factors, these B cells secrete antibodies in vitro but remain unable to secrete autoantibodies in vivo. Overall, our data demonstrate that activation of the PI3K pathway leads high-avidity autoreactive B cells to breach central, but not late, stages of peripheral tolerance.
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Affiliation(s)
- Sarah A Greaves
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO
| | - Jacob N Peterson
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO
| | - Pamela Strauch
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO
| | - Raul M Torres
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO.,Department of Biomedical Research, National Jewish Health, Denver, CO
| | - Roberta Pelanda
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO .,Department of Biomedical Research, National Jewish Health, Denver, CO
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12
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Benhamou D, Labi V, Getahun A, Benchetrit E, Dowery R, Rajewsky K, Cambier JC, Melamed D. The c-Myc/miR17-92/PTEN Axis Tunes PI3K Activity to Control Expression of Recombination Activating Genes in Early B Cell Development. Front Immunol 2018; 9:2715. [PMID: 30524445 PMCID: PMC6262168 DOI: 10.3389/fimmu.2018.02715] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 11/05/2018] [Indexed: 11/13/2022] Open
Abstract
Appropriate PI3K signals generated by the antigen receptor are essential to promote B cell development. Regulation of recombination activating gene (RAG)-1 and RAG-2 expression is one key process that is mediated by PI3K to ensure developmental progression and selection. When PI3K signals are too high or too low, expression of RAGs does not turn off and B cell development is impaired or blocked. Yet, the mechanism which tunes PI3K activity to control RAG expression during B cell development in the bone marrow is unknown. Recently we showed that a c-Myc/miR17-92/PTEN axis regulates PI3K activity for positive and negative selection of immature B cells. Here, we show that the c-Myc/miR17-92/PTEN axis tunes PI3K activity to control the expression of RAGs in proB cells. Using different genetically engineered mouse models we show that impaired function of the c-Myc/miR17-92/PTEN axis alters the PI3K/Akt/Foxo1 pathway to result in dis-regulated expression of RAG and a block in B cell development. Studies using 38c-13 B lymphoma cells, where RAGs are constitutively expressed, suggest that this regulatory effect is mediated post-translationally through Foxo1.
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Affiliation(s)
- David Benhamou
- Department of Immunology, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Verena Labi
- Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Division of Developmental Immunology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - Andrew Getahun
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Eli Benchetrit
- Department of Immunology, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Reem Dowery
- Department of Immunology, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Klaus Rajewsky
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - John C Cambier
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Doron Melamed
- Department of Immunology, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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13
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Ottens K, Hinman RM, Barrios E, Skaug B, Davis LS, Li QZ, Castrillon DH, Satterthwaite AB. Foxo3 Promotes Apoptosis of B Cell Receptor-Stimulated Immature B Cells, Thus Limiting the Window for Receptor Editing. THE JOURNAL OF IMMUNOLOGY 2018; 201:940-949. [PMID: 29950509 DOI: 10.4049/jimmunol.1701070] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 06/02/2018] [Indexed: 12/29/2022]
Abstract
Central tolerance checkpoints are critical for the elimination of autoreactive B cells and the prevention of autoimmunity. When autoreactive B cells encounter their Ag at the immature B cell stage, BCR cross-linking induces receptor editing, followed by apoptosis if edited cells remain autoreactive. Although the transcription factor Foxo1 is known to promote receptor editing, the role of the related factor Foxo3 in central B cell tolerance is poorly understood. We find that BCR-stimulated immature B cells from Foxo3-deficient mice demonstrate reduced apoptosis compared with wild type cells. Despite this, Foxo3-/- mice do not develop increased autoantibodies. This suggests that the increased survival of Foxo3-/- immature B cells allows additional rounds of receptor editing, resulting in more cells "redeeming" themselves by becoming nonautoreactive. Indeed, increased Igλ usage and increased recombining sequence recombination among Igλ-expressing cells were observed in Foxo3-/- mice, indicative of increased receptor editing. We also observed that deletion of high-affinity autoreactive cells was intact in the absence of Foxo3 in the anti-hen egg lysozyme (HEL)/membrane-bound HEL model. However, Foxo3 levels in B cells from systemic lupus erythematosus (SLE) patients were inversely correlated with disease activity and reduced in patients with elevated anti-dsDNA Abs. Although this is likely due in part to increased B cell activation in these SLE patients, it is also possible that low-affinity B cells that remain autoreactive after editing may survive inappropriately in the absence of Foxo3 and become activated to secrete autoantibodies in the context of other SLE-associated defects.
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Affiliation(s)
- Kristina Ottens
- Rheumatic Diseases Division, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Rochelle M Hinman
- Rheumatic Diseases Division, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Evan Barrios
- Rheumatic Diseases Division, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Brian Skaug
- Rheumatic Diseases Division, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Laurie S Davis
- Rheumatic Diseases Division, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Quan-Zhen Li
- Department of Immunology, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Diego H Castrillon
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, TX 75390; and.,Simmons Comprehensive Cancer Center, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Anne B Satterthwaite
- Rheumatic Diseases Division, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390; .,Department of Immunology, The University of Texas Southwestern Medical Center, Dallas, TX 75390
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14
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Greaves SA, Peterson JN, Torres RM, Pelanda R. Activation of the MEK-ERK Pathway Is Necessary but Not Sufficient for Breaking Central B Cell Tolerance. Front Immunol 2018; 9:707. [PMID: 29686680 PMCID: PMC5900439 DOI: 10.3389/fimmu.2018.00707] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/22/2018] [Indexed: 01/12/2023] Open
Abstract
Newly generated bone marrow B cells are positively selected into the peripheral lymphoid tissue only when they express a B cell receptor (BCR) that is nonautoreactive or one that binds self-antigen with only minimal avidity. This positive selection process, moreover, is critically contingent on the ligand-independent tonic signals transduced by the BCR. We have previously shown that when autoreactive B cells express an active form of the rat sarcoma (RAS) oncogene, they upregulate the receptor for the B cell activating factor (BAFFR) and undergo differentiation in vitro and positive selection into the spleen in vivo, overcoming central tolerance. Based on the in vitro use of pharmacologic inhibitors, we further showed that this cell differentiation process is critically dependent on the activation of the mitogen-activated protein kinase kinase pathway MEK (MAPKK)-extracellular signal-regulated kinase (ERK), which is downstream of RAS. Here, we next investigated if activation of ERK is not only necessary but also sufficient to break central B cell tolerance and induce differentiation of autoreactive B cells in vitro and in vivo. Our results demonstrate that activation of ERK is critical for upregulating BAFFR and overcoming suboptimal levels of tonic BCR signals or low amounts of antigen-induced BCR signals during in vitro B cell differentiation. However, direct activation of ERK does not lead high avidity autoreactive B cells to increase BAFFR levels and undergo positive selection and differentiation in vivo. B cell-specific MEK-ERK activation in mice is also unable to lead to autoantibody secretion, and this in spite of a general increase of serum immunoglobulin levels. These findings indicate that additional pathways downstream of RAS are required for high avidity autoreactive B cells to break central and/or peripheral tolerance.
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Affiliation(s)
- Sarah A Greaves
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Jacob N Peterson
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Raul M Torres
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States.,Department of Biomedical Research, National Jewish Health, Denver, CO, United States
| | - Roberta Pelanda
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States.,Department of Biomedical Research, National Jewish Health, Denver, CO, United States
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15
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Veselits M, Tanaka A, Chen Y, Hamel K, Mandal M, Kandasamy M, Manicassamy B, O'Neill SK, Wilson P, Sciammas R, Clark MR. Igβ ubiquitination activates PI3K signals required for endosomal sorting. J Exp Med 2017; 214:3775-3790. [PMID: 29141870 PMCID: PMC5716028 DOI: 10.1084/jem.20161868] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 07/20/2017] [Accepted: 09/12/2017] [Indexed: 12/26/2022] Open
Abstract
Veselits et al. show that Igβ ubiquitination activates PI3K and the accumulation of PIP3 on BCR-associated endosomal membranes, which is necessary and sufficient for sorting into classical antigen-processing compartments. Surprisingly, proper BCR sorting is critical for endosomal TLR activation yet dispensable for T-dependent humoral immunity. A wealth of in vitro data has demonstrated a central role for receptor ubiquitination in endocytic sorting. However, how receptor ubiquitination functions in vivo is poorly understood. Herein, we report that ablation of B cell antigen receptor ubiquitination in vivo uncouples the receptor from CD19 phosphorylation and phosphatidylinositol 3-kinase (PI3K) signals. These signals are necessary and sufficient for accumulating phosphatidylinositol (3,4,5)-trisphosphate (PIP3) on B cell receptor–containing early endosomes and proper sorting into the MHC class II antigen-presenting compartment (MIIC). Surprisingly, MIIC targeting is dispensable for T cell–dependent immunity. Rather, it is critical for activating endosomal toll-like receptors and antiviral humoral immunity. These findings demonstrate a novel mechanism of receptor endosomal signaling required for specific peripheral immune responses.
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Affiliation(s)
- Margaret Veselits
- Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, Departments of Medicine and Pathology, University of Chicago, Chicago, IL
| | - Azusa Tanaka
- Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, Departments of Medicine and Pathology, University of Chicago, Chicago, IL
| | - Yaoqing Chen
- Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, Departments of Medicine and Pathology, University of Chicago, Chicago, IL
| | - Keith Hamel
- Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, Departments of Medicine and Pathology, University of Chicago, Chicago, IL
| | - Malay Mandal
- Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, Departments of Medicine and Pathology, University of Chicago, Chicago, IL
| | | | | | | | - Patrick Wilson
- Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, Departments of Medicine and Pathology, University of Chicago, Chicago, IL
| | - Roger Sciammas
- Center for Comparative Medicine, University of California, Davis, Davis, CA
| | - Marcus R Clark
- Section of Rheumatology and Gwen Knapp Center for Lupus and Immunology Research, Departments of Medicine and Pathology, University of Chicago, Chicago, IL
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16
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Iacoangeli A, Lui A, Haines A, Ohta Y, Flajnik M, Hsu E. Evidence for Ig Light Chain Isotype Exclusion in Shark B Lymphocytes Suggests Ordered Mechanisms. THE JOURNAL OF IMMUNOLOGY 2017; 199:1875-1885. [PMID: 28760881 DOI: 10.4049/jimmunol.1700762] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 06/27/2017] [Indexed: 01/06/2023]
Abstract
Unlike most vertebrates, the shark IgL gene organization precludes secondary rearrangements that delete self-reactive VJ rearranged genes. Nurse sharks express four L chain isotypes, κ, λ, σ, and σ-2, encoded by 35 functional minigenes or clusters. The sequence of gene activation/expression and receptor editing of these isotypes have not been studied. We therefore investigated the extent of isotypic exclusion in separated B cell subpopulations. Surface Ig (sIg)κ-expressing cells, isolated with mAb LK14 that recognizes Cκ, carry predominantly nonproductive rearrangements of other L chain isotypes. Conversely, after depletion with LK14, sIgM+ cells contained largely nonproductive κ and enrichment for in-frame VJ of the others. Because some isotypic inclusion was observed at the mRNA level, expression in the BCR was examined. Functional λ mRNA was obtained, as expected, from the LK14-depleted population, but was also in sIgκ+ splenocytes. Whereas λ somatic mutants from the depleted sample displayed evidence of positive selection, the λ genes in sIgκ+ cells accumulated bystander mutations indicating a failure to express their products at the cell surface in association with the BCR H chain. In conclusion, a shark B cell expresses one L chain isotype at the surface and other isotypes as nonproductive VJ, sterile transcripts, or in-frame VJ whose products may not associate with the H chain. Based on the mRNA content found in the B cell subpopulations, an order of L chain gene activation is suggested as: σ-2 followed by κ, then σ and λ.
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Affiliation(s)
- Anna Iacoangeli
- Tisch Multiple Sclerosis Research Center of New York, New York, NY 10019
| | - Anita Lui
- Department of Physiology and Pharmacology, State University of New York Health Science Center at Brooklyn, Brooklyn, NY 11203; and
| | - Ashley Haines
- Department of Microbiology and Immunology, University of Maryland Baltimore, Baltimore, MD 21201
| | - Yuko Ohta
- Department of Microbiology and Immunology, University of Maryland Baltimore, Baltimore, MD 21201
| | - Martin Flajnik
- Department of Microbiology and Immunology, University of Maryland Baltimore, Baltimore, MD 21201
| | - Ellen Hsu
- Department of Physiology and Pharmacology, State University of New York Health Science Center at Brooklyn, Brooklyn, NY 11203; and
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17
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Hemon P, Renaudineau Y, Debant M, Le Goux N, Mukherjee S, Brooks W, Mignen O. Calcium Signaling: From Normal B Cell Development to Tolerance Breakdown and Autoimmunity. Clin Rev Allergy Immunol 2017; 53:141-165. [DOI: 10.1007/s12016-017-8607-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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18
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Mediation of transitional B cell maturation in the absence of functional Bruton's tyrosine kinase. Sci Rep 2017; 7:46029. [PMID: 28378771 PMCID: PMC5380950 DOI: 10.1038/srep46029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 03/08/2017] [Indexed: 01/09/2023] Open
Abstract
X-linked immune-deficient (Xid) mice, carrying a mutation in Bruton’s tyrosine kinase (Btk), have multiple B cell lineage differentiation defects. We now show that, while Xid mice showed only mild reduction in the frequency of the late transitional (T2) stage of peripheral B cells, the defect became severe when the Xid genotype was combined with either a CD40-null, a TCRbeta-null or an MHC class II (MHCII)-null genotype. Purified Xid T1 and T2 B cells survived poorly in vitro compared to wild-type (WT) cells. BAFF rescued WT but not Xid T1 and T2 B cells from death in culture, while CD40 ligation equivalently rescued both. Xid transitional B cells ex vivo showed low levels of the p100 protein substrate for non-canonical NF-kappaB signalling. In vitro, CD40 ligation induced equivalent activation of the canonical but not of the non-canonical NF-kappaB pathway in Xid and WT T1 and T2 B cells. CD40 ligation efficiently rescued p100-null T1 B cells from neglect-induced death in vitro. These data indicate that CD40-mediated signals, likely from CD4 T cells, can mediate peripheral transitional B cell maturation independent of Btk and the non-canonical NF-kappaB pathway, and thus contribute to the understanding of the complexities of peripheral B cell maturation.
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19
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Abstract
Immune tolerance hinders the potentially destructive responses of lymphocytes to host tissues. Tolerance is regulated at the stage of immature B cell development (central tolerance) by clonal deletion, involving apoptosis, and by receptor editing, which reprogrammes the specificity of B cells through secondary recombination of antibody genes. Recent mechanistic studies have begun to elucidate how these divergent mechanisms are controlled. Single-cell antibody cloning has revealed defects of B cell central tolerance in human autoimmune diseases and in several human immunodeficiency diseases caused by single gene mutations, which indicates the relevance of B cell tolerance to disease and suggests possible genetic pathways that regulate tolerance.
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20
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Li S, Liu W, Li Y, Zhao S, Liu C, Hu M, Yue W, Liu Y, Wang Y, Yang R, Xiang R, Liu F. Contribution of secondary Igkappa rearrangement to primary immunoglobulin repertoire diversification. Mol Immunol 2016; 78:193-206. [PMID: 27665270 DOI: 10.1016/j.molimm.2016.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 09/01/2016] [Accepted: 09/06/2016] [Indexed: 10/21/2022]
Abstract
Abs reactive to DNA and DNA/histone complexes are a distinguished characteristic of primary immunoglobulin repertoires in autoimmune B6.MRL-Faslpr and MRL/MpJ-Faslpr mice. These mice are defective in Fas receptor, which is critical for the apoptosis of autoreactive B cells by an extrinsic pathway. In the present study, we explored the possibility that bone marrow small pre-B and immature B cells from adult B6.MRL-Faslpr mice and MRL/MpJ-Faslpr mice respectively, which contain autoreactive B-cell antigen receptors (BCR) and manifest autoimmune syndromes, exhibit enhanced receptor editing patterns. Indeed, FASlpr pre B and immature B cells were shown to possess more ongoing replacements of non-productive (nP) than productive (P) primary VκJκ rearrangements. Significantly, the P vs nP ratios of these replaced primary rearrangements were 1:2, thus indicating that κ light-chain production appears not to inhibit secondary rearrangements. In addition, we identified multiple atypical rearrangements, such as Vκ cRS (cryptic recombination signals) cleavages. These results suggest that the onset of light chain secondary rearrangements persists similarly as a non-selected mode and independent of BCR autoreactivity during certain developmental windows of bone marrow B cells in lupus-prone mice and control, and leads us to propose the function of secondary, de novo Igκ rearrangements to increase BCR diversity.
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Affiliation(s)
- Shufang Li
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Wei Liu
- Tianjin Entry-Exit Inspection and Quarantine Bureau, Tianjin 300308, China
| | - Yinghui Li
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Shaorong Zhao
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Can Liu
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Mengyun Hu
- Collage of Life Science, Nankai University, Tianjin, 300071, China
| | - Wei Yue
- Department of Neurology, Huanhu Hospital, Tianjin 300060, China
| | - Yanhua Liu
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Yue Wang
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Rongcun Yang
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China
| | - Rong Xiang
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China.
| | - Feifei Liu
- Department of Immunology, School of Medicine, Nankai University, Tianjin 300071, China.
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21
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Benhamou D, Labi V, Novak R, Dai I, Shafir-Alon S, Weiss A, Gaujoux R, Arnold R, Shen-Orr SS, Rajewsky K, Melamed D. A c-Myc/miR17-92/Pten Axis Controls PI3K-Mediated Positive and Negative Selection in B Cell Development and Reconstitutes CD19 Deficiency. Cell Rep 2016; 16:419-431. [DOI: 10.1016/j.celrep.2016.05.084] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 04/14/2016] [Accepted: 05/19/2016] [Indexed: 01/13/2023] Open
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22
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Bonami RH, Thomas JW. Targeting Anti-Insulin B Cell Receptors Improves Receptor Editing in Type 1 Diabetes-Prone Mice. THE JOURNAL OF IMMUNOLOGY 2015; 195:4730-41. [PMID: 26432895 DOI: 10.4049/jimmunol.1500438] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 09/08/2015] [Indexed: 12/11/2022]
Abstract
Autoreactive B lymphocytes that commonly arise in the developing repertoire can be salvaged by receptor editing, a central tolerance mechanism that alters BCR specificity through continued L chain rearrangement. It is unknown whether autoantigens with weak cross-linking potential, such as insulin, elicit receptor editing, or whether this process is dysregulated in related autoimmunity. To resolve these issues, we developed an editing-competent model in which anti-insulin Vκ125 was targeted to the Igκ locus and paired with anti-insulin VH125Tg. Physiologic, circulating insulin increased RAG-2 expression and was associated with BCR replacement that eliminated autoantigen recognition in a proportion of developing anti-insulin B lymphocytes. The proportion of anti-insulin B cells that underwent receptor editing was reduced in the type 1 diabetes-prone NOD strain relative to a nonautoimmune strain. Resistance to editing was associated with increased surface IgM expression on immature (but not transitional or mature) anti-insulin B cells in the NOD strain. The actions of mAb123 on central tolerance were also investigated, because selective targeting of insulin-occupied BCR by mAb123 eliminates anti-insulin B lymphocytes and prevents type 1 diabetes. Autoantigen targeting by mAb123 increased RAG-2 expression and dramatically enhanced BCR replacement in newly developed B lymphocytes. Administering F(ab')2123 induced IgM downregulation and reduced the frequency of anti-insulin B lymphocytes within the polyclonal repertoire of VH125Tg/NOD mice, suggesting enhanced central tolerance by direct BCR interaction. These findings indicate that weak or faulty checkpoints for central tolerance can be overcome by autoantigen-specific immunomodulatory therapy.
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Affiliation(s)
- Rachel H Bonami
- Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University, Nashville, TN 37232; and
| | - James W Thomas
- Division of Rheumatology and Immunology, Department of Medicine, Vanderbilt University, Nashville, TN 37232; and Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville TN 37232
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23
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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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24
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Hüttl S, Kläsener K, Schweizer M, Schneppenheim J, Oberg HH, Kabelitz D, Reth M, Saftig P, Schröder B. Processing of CD74 by the Intramembrane Protease SPPL2a Is Critical for B Cell Receptor Signaling in Transitional B Cells. THE JOURNAL OF IMMUNOLOGY 2015; 195:1548-63. [PMID: 26157172 DOI: 10.4049/jimmunol.1403171] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 06/09/2015] [Indexed: 12/16/2022]
Abstract
The invariant chain (CD74), a chaperone in MHC class II-mediated Ag presentation, is sequentially processed by different endosomal proteases. We reported recently that clearance of the final membrane-bound N-terminal fragment (NTF) of CD74 is mediated by the intramembrane protease signal peptide peptidase-like (SPPL)2a, a process critical for B cell development. In mice, SPPL2a deficiency provokes the accumulation of this NTF in endocytic vesicles, which leads to a B cell maturation arrest at the transitional 1 stage. To define the underlying mechanism, we analyzed the impact of SPPL2a deficiency on signaling pathways involved in B cell homeostasis. We demonstrate that tonic as well as BCR-induced activation of the PI3K/Akt pathway is massively compromised in SPPL2a(-/-) B cells and identify this as major cause of the B cell maturation defect in these mice. Altered BCR trafficking induces a reduction of surface IgM in SPPL2a-deficient B cells, leading to a diminished signal transmission via the BCR and the tyrosine kinase Syk. We provide evidence that in SPPL2a(-/-) mice impaired BCR signaling is to a great extent provoked by the accumulating CD74 NTF, which can interact with the BCR and Syk, and that impaired PI3K/Akt signaling and reduced surface IgM are not directly linked processes. In line with disturbances in PI3K/Akt signaling, SPPL2a(-/-) B cells show a dysregulation of the transcription factor FOXO1, causing elevated transcription of proapoptotic genes. We conclude that SPPL2a-mediated processing of CD74 NTF is indispensable to maintain appropriate levels of tonic BCR signaling to promote B cell maturation.
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Affiliation(s)
- Susann Hüttl
- Biochemical Institute, Christian Albrechts University of Kiel, D-24118 Kiel, Germany
| | - Kathrin Kläsener
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, D-79104 Freiburg, Germany; Institute for Biology III, Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany; Max Planck Institute for Immunobiology and Epigenetics, D-79108 Freiburg, Germany
| | - Michaela Schweizer
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg, Germany
| | - Janna Schneppenheim
- Institute of Anatomy, Christian Albrechts University of Kiel, D-24118 Kiel, Germany; and
| | - Hans-Heinrich Oberg
- Institute of Immunology, Christian Albrechts University of Kiel, D-24105 Kiel, Germany
| | - Dieter Kabelitz
- Institute of Immunology, Christian Albrechts University of Kiel, D-24105 Kiel, Germany
| | - Michael Reth
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, D-79104 Freiburg, Germany; Institute for Biology III, Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany; Max Planck Institute for Immunobiology and Epigenetics, D-79108 Freiburg, Germany
| | - Paul Saftig
- Biochemical Institute, Christian Albrechts University of Kiel, D-24118 Kiel, Germany
| | - Bernd Schröder
- Biochemical Institute, Christian Albrechts University of Kiel, D-24118 Kiel, Germany;
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25
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The Role of p110δ in the Development and Activation of B Lymphocytes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 850:119-35. [DOI: 10.1007/978-3-319-15774-0_9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Fitzsimmons SP, Aydanian AG, Clark KJ, Shapiro MA. Multiple factors influence the contribution of individual immunoglobulin light chain genes to the naïve antibody repertoire. BMC Immunol 2014; 15:51. [PMID: 25359572 PMCID: PMC4216371 DOI: 10.1186/s12865-014-0051-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 10/17/2014] [Indexed: 01/27/2023] Open
Abstract
Background The naïve antibody repertoire is initially dependent upon the number of germline V(D)J genes and the ability of recombined heavy and light chains to pair. Individual VH and VL genes are not equally represented in naïve mature B cells, suggesting that positive and negative selection also shape the antibody repertoire. Among the three member murine Vκ10 L chain family, the Vκ10C gene is under-represented in the antibody repertoire. Although it is structurally functional and accessible to both transcriptional and recombination machinery, the Vκ10C promoter is inefficient in pre-B cell lines and productive Vκ10C rearrangements are lost as development progresses from pre-B cells through mature B cells. This study examined VH/Vκ10 pairing, promoter mutations, Vκ10 transcript levels and receptor editing as possible factors that are responsible for loss of productive Vκ10C rearrangements in developing B cells. Results We demonstrate that the loss of Vκ10C expression is not due to an inability to pair with H chains, but is likely due to a combination of other factors. Levels of mRNA are low in sorted pre-B cells and undetectable in B cells. Mutation of a single base in the three prime region of the Vκ10C promoter increases Vκ10C promoter function in pre-B cell lines. Pre-B and B cells harbor disproportionate levels of receptor-edited productive Vκ10C rearrangements. Conclusions Our findings suggest that the weak Vκ10C promoter initially limits the amount of available Vκ10C L chain for pairing with H chains, resulting in sub-threshold levels of cell surface B cell receptors, insufficient tonic signaling and subsequent receptor editing to limit the numbers of Vκ10C-expressing B cells emigrating from the bone marrow to the periphery.
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Affiliation(s)
| | | | | | - Marjorie A Shapiro
- Laboratory of Molecular and Developmental Immunology, Division of Monoclonal Antibodies, OBP, CDER, FDA, 10903 New Hampshire Avenue, Silver Spring 20993, MD, USA.
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Activation of Ras overcomes B-cell tolerance to promote differentiation of autoreactive B cells and production of autoantibodies. Proc Natl Acad Sci U S A 2014; 111:E2797-806. [PMID: 24958853 DOI: 10.1073/pnas.1402159111] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Newly generated immature B cells are selected to enter the peripheral mature B-cell pool only if they do not bind (or bind limited amount of) self-antigen. We previously suggested that this selection relies on basal extracellular signal-regulated kinase (Erk) activation mediated by tonic B-cell antigen receptor (BCR) signaling and that this signal can be replaced by an active rat sarcoma (Ras), which are small GTPase proteins. In this study we compared the activity of Ras and Erk in nonautoreactive and autoreactive immature B cells and investigated whether activation of Ras can break tolerance. Our results demonstrate lower levels of active Erk and Ras in autoreactive immature B cells, although this is evident only when these cells display medium/high avidity for self-antigen. Basal activation of Erk in immature B cells is proportional to surface IgM and dependent on sarcoma family kinases, whereas it is independent of B-cell activating factor, IFN, and Toll-like receptor signaling. Ectopic expression of the constitutively active mutant Ras form N-RasD12 in autoreactive cells raises active Erk, halts receptor editing via PI3 kinase, and promotes differentiation via Erk, breaking central tolerance. Moreover, when B cells coexpress autoreactive and nonautoreactive BCRs, N-RasD12 leads also to a break in peripheral tolerance with the production of autoantibodies. Our findings indicate that in immature B cells, basal activation of Ras and Erk are controlled by tonic BCR signaling, and that positive changes in Ras activity can lead to a break in both central and peripheral B-cell tolerance.
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Pelanda R. Dual immunoglobulin light chain B cells: Trojan horses of autoimmunity? Curr Opin Immunol 2014; 27:53-9. [PMID: 24549093 DOI: 10.1016/j.coi.2014.01.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 01/17/2014] [Accepted: 01/23/2014] [Indexed: 10/25/2022]
Abstract
Receptor editing, a major mechanism of B cell tolerance, can also lead to allelic inclusion at the immunoglobulin light chain loci and the development of B cells that coexpress two different immunoglobulin light chains and, therefore, two antibody specificities. Most allelically included B cells express two κ chains, although rare dual-λ cells are also observed. Moreover, these cells typically coexpress an autoreactive and a nonautoreactive antibody. Thus, allelically included B cells could operate like 'Trojan horses': expression and function of the nonautoreactive antigen receptors might promote their maturation, activation, and terminal differentiation into effector cells that also express and secrete autoantibodies. Indeed, dual-κ B cells are greatly expanded into effector B cell subsets in some autoimmune mice, thus indicating they might play an important role in disease.
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Affiliation(s)
- Roberta Pelanda
- Integrated Department of Immunology, National Jewish Health and University of Colorado School of Medicine, Denver, CO 80206, USA.
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Abstract
The development and function of B lymphocytes critically depend on the non-germline B-cell antigen receptor (BCR). In addition to the diverse antigen-recognition regions, whose coding sequences are generated by the somatic DNA rearrangement, the variety of the constant domains of the Heavy Chain (HC) portion contributes to the multiplicity of the BCR types. The functions of particular classes of the HC, particularly in the context of the membrane BCR, are not completely understood. The expression of the various classes of the HC correlates with the distinct stages of B-cell development, types of B-cell subsets, and their effector functions. In this chapter, we summarize and discuss the accumulated knowledge on the role of the μ, δ, and γ HC isotypes of the conventional and precursor BCR in B-cell differentiation, selection, and engagement with (auto)antigens.
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Affiliation(s)
- Elena Surova
- Spemann Graduate School of Biology and Medicine (SGBM), Albert Ludwigs University Freiburg, Freiburg, Germany; Department of Molecular immunology, Faculty of Biology, University of Freiburg and Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Hassan Jumaa
- Spemann Graduate School of Biology and Medicine (SGBM), Albert Ludwigs University Freiburg, Freiburg, Germany; Department of Molecular immunology, Faculty of Biology, University of Freiburg and Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany; Department of Immunology, Ulm University, Ulm, Germany.
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Orchestrating B cell lymphopoiesis through interplay of IL-7 receptor and pre-B cell receptor signalling. Nat Rev Immunol 2013; 14:69-80. [PMID: 24378843 DOI: 10.1038/nri3570] [Citation(s) in RCA: 216] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The development of B cells is dependent on the sequential DNA rearrangement of immunoglobulin loci that encode subunits of the B cell receptor. The pathway navigates a crucial checkpoint that ensures expression of a signalling-competent immunoglobulin heavy chain before commitment to rearrangement and expression of an immunoglobulin light chain. The checkpoint segregates proliferation of pre-B cells from immunoglobulin light chain recombination and their differentiation into B cells. Recent advances have revealed the molecular circuitry that controls two rival signalling systems, namely the interleukin-7 (IL-7) receptor and the pre-B cell receptor, to ensure that proliferation and immunoglobulin recombination are mutually exclusive, thereby maintaining genomic integrity during B cell development.
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Internalization of B cell receptors in human EU12 μHC⁺ immature B cells specifically alters downstream signaling events. BIOMED RESEARCH INTERNATIONAL 2013; 2013:807240. [PMID: 24222917 PMCID: PMC3809603 DOI: 10.1155/2013/807240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 08/26/2013] [Indexed: 11/17/2022]
Abstract
It has been recognized for a long time that engagement of B cell antigen receptors (BCRs) on immature B cells or mature B cells leads to completely opposite cell fate decisions. The underlying mechanism remains unclear. Here, we show that crosslinking of BCRs on human EU12 μHC+ immature B cells resulted in complete internalization of cell surface BCRs. After loss of cell surface BCRs, restimulation of EU12 μHC+ cells showed impaired Ca2+ flux, delayed SYK phosphorylation, and decreased CD19 and FOXO1 phosphorylation, which differ from those in mature Daudi or Ramos B cells with partial internalization of BCRs. In contrast, sustained phosphorylation and reactivation of ERK upon restimulation were observed in the EU12 μHC+ cells after BCR internalization. Taken together, these results show that complete internalization of cell surface BCRs in EU12 μHC+ cells specifically alters the downstream signaling events, which may favor receptor editing versus cell activation.
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Anbazhagan K, Rabbind Singh A, Isabelle P, Stella I, Céline ADM, Bissac E, Bertrand B, Rémy N, Naomi T, Vincent F, Rochette J, Lassoued K. Human pre-B cell receptor signal transduction: evidence for distinct roles of PI3kinase and MAP-kinase signalling pathways. IMMUNITY INFLAMMATION AND DISEASE 2013; 1:26-36. [PMID: 25400915 PMCID: PMC4217539 DOI: 10.1002/iid3.4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 07/08/2013] [Accepted: 07/11/2013] [Indexed: 12/16/2022]
Abstract
Pre-BCR acts as a critical checkpoint in B cell development. However, its signalling cascade still remains indistinctly characterised in human. We investigated pre-BCR signalling pathway to examine its regulation in normal primary pre-B lymphocytes and pre-B cell lines. In cell lines, early signalling events occurring after pre-BCR stimulation include phosphorylation of Lyn, Blk and Syk together with ZAP70, Btk, Vav, PLC-γ2 and various adaptor proteins, such as BLNK, LAB, LAT and SLP-76. Further downstream, these molecules induced activation of the PI3K/AKT and MAP-kinase resulting in an augmentation of canonical NF-κB pathways and cFos/AP1 activation. PI3K and MAPK exerted opposing effects on the pre-BCR-induced activation of the canonical NF-κB and c-Fos/AP1 pathways. Immediate nuclear export of FoxO3A and delayed import of IRF4 were additional events observed after pre-BCR crosslinking in primary cells. Pre-BCR-induced down-regulation of Rag1, Rag2, E2A and Pax5 transcripts occurred in a PI3K-dependent manner. Finally we bring evidence that pre-BCR stimulation or co stimulation with CD19 enhances cell cycle signal.
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Affiliation(s)
- Kolandaswamy Anbazhagan
- Inserm/UMR925, Université Picardie Jules Verne, Laboratoire d'Immunologie, UFR de Médecine 3, rue des Louvels, 80036, Amiens, France
| | - Amrathlal Rabbind Singh
- Inserm/UMR925, Université Picardie Jules Verne, Laboratoire d'Immunologie, UFR de Médecine 3, rue des Louvels, 80036, Amiens, France
| | - Piec Isabelle
- Inserm/UMR925, Université Picardie Jules Verne, Laboratoire d'Immunologie, UFR de Médecine 3, rue des Louvels, 80036, Amiens, France
| | - Ibata Stella
- Inserm/UMR925, Université Picardie Jules Verne, Laboratoire d'Immunologie, UFR de Médecine 3, rue des Louvels, 80036, Amiens, France
| | - Alleaume-De Martel Céline
- Inserm/UMR925, Université Picardie Jules Verne, Laboratoire d'Immunologie, UFR de Médecine 3, rue des Louvels, 80036, Amiens, France
| | - Eliane Bissac
- Inserm/UMR925, Université Picardie Jules Verne, Laboratoire d'Immunologie, UFR de Médecine 3, rue des Louvels, 80036, Amiens, France
| | - Brassart Bertrand
- Inserm/UMR925, Université Picardie Jules Verne, Laboratoire d'Immunologie, UFR de Médecine 3, rue des Louvels, 80036, Amiens, France
| | - Nyga Rémy
- Inserm/UMR925, Université Picardie Jules Verne, Laboratoire d'Immunologie, UFR de Médecine 3, rue des Louvels, 80036, Amiens, France
| | - Taylor Naomi
- CNRS/UMR 5535, Institut de Génétique Moléculaire de Montpellier 1919 Route de Mende, 34293, Montpellier, Cedex 5, France
| | - Fuentes Vincent
- Inserm/UMR925, Université Picardie Jules Verne, Laboratoire d'Immunologie, UFR de Médecine 3, rue des Louvels, 80036, Amiens, France
| | - Jacques Rochette
- Inserm/UMR925, Université Picardie Jules Verne, Laboratoire d'Immunologie, UFR de Médecine 3, rue des Louvels, 80036, Amiens, France
| | - Kaïss Lassoued
- Inserm/UMR925, Université Picardie Jules Verne, Laboratoire d'Immunologie, UFR de Médecine 3, rue des Louvels, 80036, Amiens, France
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Peng C, Eckhardt LA. Role of the Igh intronic enhancer Eμ in clonal selection at the pre-B to immature B cell transition. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2013; 191:4399-411. [PMID: 24058175 PMCID: PMC3810302 DOI: 10.4049/jimmunol.1301858] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We previously described a checkpoint for allelic exclusion that occurs at the pre-B cell to immature B cell transition and is dependent upon the IgH intronic enhancer, Eμ. We now provide evidence that the breach in allelic exclusion associated with Eμ deletion results from decreased Igμ levels that make it difficult for emerging BCRs to reach the signaling threshold required for positive selection into the immature B cell compartment. We show that this compartment is smaller in mice carrying an Eμ-deficient, but functional, IgH allele (VHΔ(a)). Pre-B cells in such mice produce ≈ 50% wild-type levels of Igμ (mRNA and protein), and this is associated with diminished signals, as measured by phosphorylation of pre-BCR/BCR downstream signaling proteins. Providing Eμ-deficient mice with a preassembled VL gene led not only to a larger immature B cell compartment but also to a decrease in "double-producers," suggesting that H chain/L chain combinations with superior signaling properties can overcome the signaling defect associated with low Igμ-chain and can eliminate the selective advantage of "double-producers" that achieve higher Igμ-chain levels through expression of a second IgH allele. Finally, we found that "double-producers" in Eμ-deficient mice include a subpopulation with autoreactive BCRs. We infer that BCRs with IgH chain from the Eμ-deficient allele are ignored during negative selection owing to their comparatively low density. In summary, these studies show that Eμ's effect on IgH levels at the pre-B cell to immature B cell transition strongly influences allelic exclusion, the breadth of the mature BCR repertoire, and the emergence of autoimmune B cells.
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MESH Headings
- Animals
- B-Lymphocytes/metabolism
- Cell Differentiation
- Cells, Cultured
- Clonal Selection, Antigen-Mediated
- Enhancer Elements, Genetic
- Genes, Immunoglobulin Heavy Chain
- Immunoglobulin Fragments/genetics
- Immunoglobulin Fragments/immunology
- Immunoglobulin Heavy Chains/genetics
- Immunoglobulin Heavy Chains/immunology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Phosphorylation
- Precursor Cells, B-Lymphoid/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Antigen, B-Cell/immunology
- Receptors, Antigen, B-Cell/metabolism
- Regulatory Sequences, Nucleic Acid
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Affiliation(s)
- Cheng Peng
- Department of Biological Sciences, Hunter College and The Graduate Center of The City University of New York, 695 Park Avenue, New York, NY, 10065
| | - Laurel A. Eckhardt
- Department of Biological Sciences, Hunter College and The Graduate Center of The City University of New York, 695 Park Avenue, New York, NY, 10065
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36
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Maranhão AQ, Costa MBW, Guedes L, Moraes-Vieira PM, Raiol T, Brigido MM. A mouse variable gene fragment binds to DNA independently of the BCR context: a possible role for immature B-cell repertoire establishment. PLoS One 2013; 8:e72625. [PMID: 24023756 PMCID: PMC3759382 DOI: 10.1371/journal.pone.0072625] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 07/11/2013] [Indexed: 01/13/2023] Open
Abstract
B-cell maturation occurs in several steps and requires constant stimulus for its continuing development. From the emergence of the pre-B-cell receptor, signal transduction stimulates and supports B-cell development. Current viewpoints indicate that both positive selection pressure for autoantigens and tonic signaling constitutively stimulate B-cell maturation. In this work, we tested for the presence of a putative DNA binding site in a variable gene segment in a germline configuration, independently of VDJ recombination. After a survey of the public antibody databases, we chose a single mouse heavy variable gene segment that is highly represented in anti-nucleic acid antibodies and tested it for ssDNA binding. A phage display approach was used to search for intrinsic binding to oligo deoxythymidine. The results revealed that binding to an antigen can be influenced by the use of a specific DNA binding V[Formula: see text] gene segment. Our data support the idea that some variable genes have intrinsic reactivity towards specific types of endogenous autoantigens, and this property may contribute to the establishment of the immature B-cell repertoire.
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Affiliation(s)
- Andrea Queiroz Maranhão
- Laboratório de Biologia Molecular, Instituto de Biologia, Universidade de Brasília, Brasília, Distrito Federal, Brazil
| | - Maria Beatriz Walter Costa
- Laboratório de Bioinformática, Instituto de Biologia, Universidade de Brasília, Brasília, Distrito Federal, Brazil
| | - Leonardo Guedes
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Pedro Manoel Moraes-Vieira
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Tainá Raiol
- Laboratório de Bioinformática, Instituto de Biologia, Universidade de Brasília, Brasília, Distrito Federal, Brazil
| | - Marcelo Macedo Brigido
- Laboratório de Biologia Molecular, Instituto de Biologia, Universidade de Brasília, Brasília, Distrito Federal, Brazil
- Laboratório de Bioinformática, Instituto de Biologia, Universidade de Brasília, Brasília, Distrito Federal, Brazil
- * E-mail:
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Rowland SL, Tuttle K, Torres RM, Pelanda R. Antigen and cytokine receptor signals guide the development of the naïve mature B cell repertoire. Immunol Res 2013; 55:231-40. [PMID: 22941591 DOI: 10.1007/s12026-012-8366-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Immature B cells are generated daily in the bone marrow tissue. More than half of the newly generated immature B cells are autoreactive and bind a self-antigen, while the others are nonautoreactive. A selection process has evolved on the one hand to thwart development of autoreactive immature B cells and, on the other hand, to promote further differentiation of nonautoreactive immature B cells into transitional and mature B cells. These negative and positive selection events are carefully regulated by signals that emanate from the antigen receptor, whether antigen-mediated or tonic, and are influenced by signals that are generated by receptors that bind cytokines, chemokines, and other factors produced in the bone marrow tissue. These signals, therefore, are the predominant driving forces for the generation of a B cell population that is capable of protecting the body from infections while maintaining self-tolerance. Here, we review recent findings from our group and others that describe how tonic antigen receptor signaling and bone marrow cytokines regulate the selection of immature B cells.
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Affiliation(s)
- Sarah L Rowland
- Integrated Department of Immunology, University of Colorado School of Medicine, National Jewish Health, Denver, CO, USA
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Abstract
Phosphoinositide 3-kinases (PI3Ks) control many important aspects of immune cell development, differentiation, and function. Mammals have eight PI3K catalytic subunits that are divided into three classes based on similarities in structure and function. Specific roles for the class I PI3Ks have been broadly investigated and are relatively well understood, as is the function of their corresponding phosphatases. More recently, specific roles for the class II and class III PI3Ks have emerged. Through vertebrate evolution and in parallel with the evolution of adaptive immunity, there has been a dramatic increase not only in the genes for PI3K subunits but also in genes for phosphatases that act on 3-phosphoinositides and in 3-phosphoinositide-binding proteins. Our understanding of the PI3Ks in immunity is guided by fundamental discoveries made in simpler model organisms as well as by appreciating new adaptations of this signaling module in mammals in general and in immune cells in particular.
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Affiliation(s)
- Klaus Okkenhaug
- Laboratory of Lymphocyte Signaling and Development, The Babraham Institute, Cambridge, CB22 3AT, United Kingdom.
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Pauls SD, Lafarge ST, Landego I, Zhang T, Marshall AJ. The phosphoinositide 3-kinase signaling pathway in normal and malignant B cells: activation mechanisms, regulation and impact on cellular functions. Front Immunol 2012; 3:224. [PMID: 22908014 PMCID: PMC3414724 DOI: 10.3389/fimmu.2012.00224] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 07/10/2012] [Indexed: 12/20/2022] Open
Abstract
The phosphoinositide 3-kinase (PI3K) pathway is a central signal transduction axis controlling normal B cell homeostasis and activation in humoral immunity. The p110δ PI3K catalytic subunit has emerged as a critical mediator of multiple B cell functions. The activity of this pathway is regulated at multiple levels, with inositol phosphatases PTEN and SHIP both playing critical roles. When deregulated, the PI3K pathway can contribute to B cell malignancies and autoantibody production. This review summarizes current knowledge on key mechanisms that activate and regulate the PI3K pathway and influence normal B cell functional responses including the development of B cell subsets, antigen presentation, immunoglobulin isotype switch, germinal center responses, and maintenance of B cell anergy. We also discuss PI3K pathway alterations reported in select B cell malignancies and highlight studies indicating the functional significance of this pathway in malignant B cell survival and growth within tissue microenvironments. Finally, we comment on early clinical trial results, which support PI3K inhibition as a promising treatment of chronic lymphocytic leukemia.
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Affiliation(s)
- Samantha D Pauls
- Department of Immunology, University of Manitoba, Winnipeg, MB, Canada
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Limon JJ, Fruman DA. Akt and mTOR in B Cell Activation and Differentiation. Front Immunol 2012; 3:228. [PMID: 22888331 PMCID: PMC3412259 DOI: 10.3389/fimmu.2012.00228] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 07/14/2012] [Indexed: 01/08/2023] Open
Abstract
Activation of phosphoinositide 3-kinase (PI3K) is required for B cell proliferation and survival. PI3K signaling also controls key aspects of B cell differentiation. Upon engagement of the B cell receptor (BCR), PI3K activation promotes Ca2+ mobilization and activation of NFκB-dependent transcription, events which are essential for B cell proliferation. PI3K also initiates a distinct signaling pathway involving the Akt and mTOR serine/threonine kinases. It has been generally assumed that activation of Akt and mTOR downstream of PI3K is essential for B cell function. However, Akt and mTOR have complex roles in B cell fate decisions and suppression of this pathway can enhance certain B cell responses while repressing others. In this review we will discuss genetic and pharmacological studies of Akt and mTOR function in normal B cells, and in malignancies of B cell origin.
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Affiliation(s)
- Jose J Limon
- Department of Molecular Biology and Biochemistry, Institute for Immunology, University of California Irvine Irvine, CA, USA
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Abstract
The development of an adaptive immune system based on the random generation of antigen receptors requires a stringent selection process that sifts through receptor specificities to remove those reacting with self-antigens. In the B-cell lineage, this selection process is first applied to IgM(+) immature B cells. By using increasingly sophisticated mouse models, investigators have identified the central tolerance mechanisms that negatively select autoreactive immature B cells and prevent inclusion of their antigen receptors into the peripheral B-cell pool. Additional studies have uncovered mechanisms that promote the differentiation of nonautoreactive immature B cells and their positive selection into the peripheral B-cell population. These mechanisms of central selection are fundamental to the generation of a naïve B-cell repertoire that is largely devoid of self-reactivity while capable of reacting with any foreign insult.
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Affiliation(s)
- Roberta Pelanda
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver School of Medicine, Denver, Colorado 80206, USA.
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43
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Zhou X, Xiang Y, Ding X, Garrard WT. A new hypersensitive site, HS10, and the enhancers, E3' and Ed, differentially regulate Igκ gene expression. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2012; 188:2722-32. [PMID: 22323542 PMCID: PMC3294001 DOI: 10.4049/jimmunol.1102758] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The mouse Igκ gene locus has three known transcriptional enhancers: an intronic enhancer (Ei), a 3' enhancer (E3'), and a further downstream enhancer (Ed). We previously discovered, using the chromosome conformation-capture technique, that Ei and E3' interact with a novel DNA sequence near the 3' end of the Igκ locus, specifically in B cells. In the present investigation, we examined the function of this far downstream element. The sequence is evolutionarily conserved and exhibits a plasmacytoma cell-specific DNase I-hypersensitive site in chromatin, henceforth termed HS10 in the locus. HS10 acts as a coactivator of E3' in transient transfection assays. Although HS10(-/-) mice exhibited normal patterns of B cell development, they were tested further along with E3'(-/-) and Ed(-/-) mice for their Igκ expression levels in plasma cells, as well as for both allelic and isotype exclusion in splenic B cells. HS10(-/-) and Ed(-/-), but not E3'(-/-), mice exhibited 2.5-fold lower levels of Igκ expression in antigenically challenged plasma cells. E3'(-/-) mice, but not HS10(-/-) mice, exhibited impaired IgL isotype and allelic exclusion in splenic B cells. We have suggestive results that Ed may also weakly participate in these processes. In addition, HS10(-/-) mice no longer exhibited regional chromosome interactions with E3', and they exhibited modestly reduced somatic hypermutation in the Jκ-Cκ intronic region in germinal center B cells from Peyer's patches. We conclude that the HS10, E3', and Ed differentially regulate Igκ gene dynamics.
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Affiliation(s)
- Xiaorong Zhou
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9148
- Department of Microbiology and Immunology, Medical School of Nantong University, 19 Qixiu Road, Nantong, Jiangsu 226001, PR China
| | - Yougui Xiang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9148
| | - Xiaoling Ding
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9148
| | - William T. Garrard
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9148
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Herzog S, Jumaa H. Self-recognition and clonal selection: autoreactivity drives the generation of B cells. Curr Opin Immunol 2012; 24:166-72. [PMID: 22398125 DOI: 10.1016/j.coi.2012.02.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 01/19/2012] [Accepted: 02/06/2012] [Indexed: 11/15/2022]
Abstract
The diversity of B cell receptor (BCR) specificities is generated by VDJ recombination of gene segments during early B cell development, a process which bears the risk of producing BCRs that recognize and lead to the destruction of self-structures. Traditional thoughts have mainly focused on how such putatively dangerous specificities are dealt with and in how they contribute to the development of autoimmune diseases. However, a positive or even necessary role of self-recognition during B cell development has rarely been taken into account. Now, considerable data reveal that the pre-B cell receptor (pre-BCR), which marks an important checkpoint during B cell development, acts as a surrogate autoreactive receptor. This review outlines how autoreactivity is necessary for efficient B cell development and how autoreactive receptors drive positive selection, leading to a diverse repertoire of receptor specificities in the mature B cell pool.
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Affiliation(s)
- Sebastian Herzog
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
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A self-reinforcing regulatory network triggered by limiting IL-7 activates pre-BCR signaling and differentiation. Nat Immunol 2012; 13:300-7. [PMID: 22267219 DOI: 10.1038/ni.2210] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 12/12/2011] [Indexed: 12/12/2022]
Abstract
The molecular crosstalk between the interleukin 7 receptor (IL-7R) and the precursor to the B cell antigen receptor (pre-BCR) in B lymphopoiesis has not been elucidated. Here we demonstrate that in pre-B cells, the IL-7R but not the pre-BCR was coupled to phosphatidylinositol-3-OH kinase (PI(3)K) and the kinase Akt; signaling by this pathway inhibited expression of recombination-activating gene 1 (Rag1) and Rag2. Attenuation of IL-7 signaling resulted in upregulation of the transcription factors Foxo1 and Pax5, which coactivated many pre-B cell genes, including Rag1, Rag2 and Blnk. Induction of Blnk (which encodes the signaling adaptor BLNK) enabled pre-BCR signaling via the signaling molecule Syk and promoted immunoglobulin light-chain rearrangement. BLNK expression also antagonized Akt activation, thereby augmenting the accumulation of Foxo1 and Pax5. This self-reinforcing molecular circuit seemed to sense limiting concentrations of IL-7 and functioned to constrain the proliferation of pre-B cells and trigger their differentiation.
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Vossenkämper A, Lutalo PMK, Spencer J. Translational Mini-Review Series on B cell subsets in disease. Transitional B cells in systemic lupus erythematosus and Sjögren's syndrome: clinical implications and effects of B cell-targeted therapies. Clin Exp Immunol 2012; 167:7-14. [PMID: 22132879 PMCID: PMC3248081 DOI: 10.1111/j.1365-2249.2011.04460.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/20/2011] [Indexed: 12/11/2022] Open
Abstract
Systemic lupus erythematosus (SLE) and Sjögren's syndrome are autoimmune disorders which are characterized by a disturbed B cell homeostasis which leads ultimately to dysfunction of various organs. One of the B cell subsets that appear in abnormal numbers is the population of transitional B cells, which is increased in the blood of patients with SLE and Sjögren's syndrome. Transitional B cells are newly formed B cells. In mice, transitional B cells undergo selection checks for unwanted specificity in the bone marrow and the spleen in order to eliminate autoreactive B cells from the circulating naive B cell population. In humans, the exact anatomical compartments and mechanisms of the specificity check-points for transitional B cells remain unclear, but appear to be defective in SLE and Sjögren's syndrome. This review aims to highlight the current understanding of transitional B cells and their defects in the two disorders before and after B cell-targeted therapies.
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MESH Headings
- Animals
- Antibodies, Monoclonal/therapeutic use
- Antibodies, Monoclonal, Humanized/therapeutic use
- Antibodies, Monoclonal, Murine-Derived/therapeutic use
- B-Cell Activating Factor/immunology
- B-Lymphocyte Subsets/immunology
- B-Lymphocyte Subsets/pathology
- Clinical Trials, Phase II as Topic
- Clinical Trials, Phase III as Topic
- Disease Models, Animal
- Double-Blind Method
- Humans
- Lupus Erythematosus, Systemic/immunology
- Lupus Erythematosus, Systemic/pathology
- Lupus Erythematosus, Systemic/therapy
- Lymphocyte Count
- Lymphocyte Depletion/methods
- Lymphoid Tissue/immunology
- Lymphoid Tissue/pathology
- Lymphopoiesis
- Mice
- Rituximab
- Sjogren's Syndrome/immunology
- Sjogren's Syndrome/pathology
- Sjogren's Syndrome/therapy
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Affiliation(s)
- A Vossenkämper
- Centre for Immunology and Infectious Disease, Barts and The London School of Medicine and Dentistry, Blizard Institute, London, UK.
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Shen S, Manser T. Direct reduction of antigen receptor expression in polyclonal B cell populations developing in vivo results in light chain receptor editing. THE JOURNAL OF IMMUNOLOGY 2011; 188:47-56. [PMID: 22131331 DOI: 10.4049/jimmunol.1102109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Secondary Ab V region gene segment rearrangement, termed receptor editing, is a major mechanism contributing to B lymphocyte self-tolerance. However, the parameters that determine whether a B cell undergoes editing are a current subject of debate. We tested the role that the level of BCR expression plays in the regulation of receptor editing in a polyclonal population of B cells differentiating in vivo. Expression of a short hairpin RNA for κ L chain RNA in B cells resulted in reduction in levels of this RNA and surface BCRs. Strikingly, fully mature and functional B cells that developed in vivo and efficiently expressed the short hairpin RNA predominantly expressed BCRs containing λ light chains. This shift in L chain repertoire was accompanied by inhibition of development, increased Rag gene expression, and increased λ V gene segment-cleavage events at the immature B cell stage. These data demonstrated that reducing the translation of BCRs that are members of the natural repertoire at the immature B cell stage is sufficient to promote editing.
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Affiliation(s)
- Shixue Shen
- Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Simmons KB, Wubeshet M, Ames KT, McMahan CJ, Hale JS, Fink PJ. Modulation of TCRβ surface expression during TCR revision. Cell Immunol 2011; 272:124-9. [PMID: 22138498 DOI: 10.1016/j.cellimm.2011.10.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 10/31/2011] [Indexed: 01/04/2023]
Abstract
TCR revision is a tolerance mechanism by which self-reactive TCRs expressed by mature CD4(+) peripheral T cells are replaced by receptors encoded by genes generated by post-thymic DNA rearrangement. The downmodulation of surface TCR expression initiates TCR revision, and serves as a likely trigger for the induction of the recombinase machinery. We show here in a Vβ5 transgenic mouse model system that downregulation of the self-reactive transgene-encoded TCR is not maintained by transgene loss or diminished transcription or translation. The downregulation of surface TCR expression likely occurs in two stages, only one of which requires tolerogen expression.
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Affiliation(s)
- Kalynn B Simmons
- Department of Immunology, University of Washington, Seattle, WA, USA
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49
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Zheng CH, Zhang L, Ng VTY, Shiu SCK, Huang DS. Molecular pattern discovery based on penalized matrix decomposition. IEEE/ACM TRANSACTIONS ON COMPUTATIONAL BIOLOGY AND BIOINFORMATICS 2011; 8:1592-1603. [PMID: 21519114 DOI: 10.1109/tcbb.2011.79] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A reliable and precise identification of the type of tumors is crucial to the effective treatment of cancer. With the rapid development of microarray technologies, tumor clustering based on gene expression data is becoming a powerful approach to cancer class discovery. In this paper, we apply the penalized matrix decomposition (PMD) to gene expression data to extract metasamples for clustering. The extracted metasamples capture the inherent structures of samples belong to the same class. At the same time, the PMD factors of a sample over the metasamples can be used as its class indicator in return. Compared with the conventional methods such as hierarchical clustering (HC), self-organizing maps (SOM), affinity propagation (AP) and nonnegative matrix factorization (NMF), the proposed method can identify the samples with complex classes. Moreover, the factor of PMD can be used as an index to determine the cluster number. The proposed method provides a reasonable explanation of the inconsistent classifications made by the conventional methods. In addition, it is able to discover the modules in gene expression data of conterminous developmental stages. Experiments on two representative problems show that the proposed PMD-based method is very promising to discover biological phenotypes.
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Affiliation(s)
- Chun-Hou Zheng
- College of Electrical Engineering and Automation, Anhui University, Hefei, Anhui 230039, China.
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50
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Markegard E, Trager E, Yang CWO, Zhang W, Weiss A, Roose JP. Basal LAT-diacylglycerol-RasGRP1 signals in T cells maintain TCRα gene expression. PLoS One 2011; 6:e25540. [PMID: 21966541 PMCID: PMC3180458 DOI: 10.1371/journal.pone.0025540] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 09/07/2011] [Indexed: 12/18/2022] Open
Abstract
In contrast to the well-characterized T cell receptor (TCR) signaling pathways that induce genes that drive T cell development or polarization of naïve CD4 T cells into the diverse T(H)1, T(H)2, T(H)17 and T(reg) lineages, it is unclear what signals maintain specific gene expression in mature resting T cells. Resting T cells residing in peripheral lymphoid organs exhibit low-level constitutive signaling. Whereas tonic signals in B cells are known to be critical for survival, the roles of tonic signals in peripheral T cells are unknown. Here we demonstrate that constitutive signals in Jurkat T cell lines are transduced via the adapter molecule LAT and the Ras exchange factor RasGRP1 to maintain expression of TCRα mRNA and surface expression of the TCR/CD3 complex. Independent approaches of reducing basal activity through the LAT-diacylglycerol-RasGRP pathway led to reduced constitutive Ras-MEK-ERK signals and decreased TCRα mRNA and surface TCR expression in Jurkat cells. However, loss of TCR expression takes several days in these cell line experiments. In agreement with these in vitro approaches, inducible deletion of Lat in vivo results in reduced TCRα mRNA- and surface TCR-expression in a delayed temporal manner as well. Lastly, we demonstrate that loss of basal LAT-RasGRP signals appears to lead to silencing or repression of TCRα transcription. We postulate that basal LAT-diacylglycerol-RasGRP signals fulfill a regulatory function in peripheral T lymphocytes by maintaining proper gene expression programs.
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Affiliation(s)
- Evan Markegard
- Department of Anatomy, University of California San Francisco, San Francisco, California, United States of America
| | - Evan Trager
- Department of Anatomy, University of California San Francisco, San Francisco, California, United States of America
| | - Chih-wen Ou Yang
- Department of Immunology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Weiguo Zhang
- Department of Immunology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Arthur Weiss
- Department of Medicine, University of California San Francisco, San Francisco, California, United States of America
- Department of Microbiology and Immunology and Howard Hughes Medical Institute, University of California San Francisco, San Francisco, California, United States of America
- Rosalind Russell Medical Research Center for Arthritis, University of California San Francisco, San Francisco, California, United States of America
| | - Jeroen P. Roose
- Department of Anatomy, University of California San Francisco, San Francisco, California, United States of America
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