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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Fu ZH, He SZ, Wu Y, Zhao GR. Design and deep learning of synthetic B-cell-specific promoters. Nucleic Acids Res 2023; 51:11967-11979. [PMID: 37889080 PMCID: PMC10681721 DOI: 10.1093/nar/gkad930] [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: 05/27/2023] [Revised: 09/20/2023] [Accepted: 10/10/2023] [Indexed: 10/28/2023] Open
Abstract
Synthetic biology and deep learning synergistically revolutionize our ability for decoding and recoding DNA regulatory grammar. The B-cell-specific transcriptional regulation is intricate, and unlock the potential of B-cell-specific promoters as synthetic elements is important for B-cell engineering. Here, we designed and pooled synthesized 23 640 B-cell-specific promoters that exhibit larger sequence space, B-cell-specific expression, and enable diverse transcriptional patterns in B-cells. By MPRA (Massively parallel reporter assays), we deciphered the sequence features that regulate promoter transcriptional, including motifs and motif syntax (their combination and distance). Finally, we built and trained a deep learning model capable of predicting the transcriptional strength of the immunoglobulin V gene promoter directly from sequence. Prediction of thousands of promoter variants identified in the global human population shows that polymorphisms in promoters influence the transcription of immunoglobulin V genes, which may contribute to individual differences in adaptive humoral immune responses. Our work helps to decipher the transcription mechanism in immunoglobulin genes and offers thousands of non-similar promoters for B-cell engineering.
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Affiliation(s)
- Zong-Heng Fu
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- Frontiers Research Institute for Synthetic Biology, Tianjin University, Tianjin 300072, China
| | - Si-Zhe He
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- Frontiers Research Institute for Synthetic Biology, Tianjin University, Tianjin 300072, China
| | - Yi Wu
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- Frontiers Research Institute for Synthetic Biology, Tianjin University, Tianjin 300072, China
| | - Guang-Rong Zhao
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
- Frontiers Research Institute for Synthetic Biology, Tianjin University, Tianjin 300072, China
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4
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Braams M, Pike-Overzet K, Staal FJT. The recombinase activating genes: architects of immune diversity during lymphocyte development. Front Immunol 2023; 14:1210818. [PMID: 37497222 PMCID: PMC10367010 DOI: 10.3389/fimmu.2023.1210818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Accepted: 06/19/2023] [Indexed: 07/28/2023] Open
Abstract
The mature lymphocyte population of a healthy individual has the remarkable ability to recognise an immense variety of antigens. Instead of encoding a unique gene for each potential antigen receptor, evolution has used gene rearrangements, also known as variable, diversity, and joining gene segment (V(D)J) recombination. This process is critical for lymphocyte development and relies on recombination-activating genes-1 (RAG1) and RAG2, here collectively referred to as RAG. RAG serves as powerful genome editing tools for lymphocytes and is strictly regulated to prevent dysregulation. However, in the case of dysregulation, RAG has been implicated in cases of cancer, autoimmunity and severe combined immunodeficiency (SCID). This review examines functional protein domains and motifs of RAG, describes advances in our understanding of the function and (dys)regulation of RAG, discuss new therapeutic options, such as gene therapy, for RAG deficiencies, and explore in vitro and in vivo methods for determining RAG activity and target specificity.
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Affiliation(s)
- Merijn Braams
- Department of Immunology, Leiden University Medical Centre, Leiden, Netherlands
| | - Karin Pike-Overzet
- Department of Immunology, Leiden University Medical Centre, Leiden, Netherlands
| | - Frank J. T. Staal
- Department of Immunology, Leiden University Medical Centre, Leiden, Netherlands
- Novo Nordisk Foundation Centre for Stem Cell Medicine (reNEW), Leiden University Medical Centre, Leiden, Netherlands
- Department of Paediatrics, Leiden University Medical Centre, Leiden, Netherlands
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5
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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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6
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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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7
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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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8
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Homeostasis and regulation of autoreactive B cells. Cell Mol Immunol 2020; 17:561-569. [PMID: 32382130 DOI: 10.1038/s41423-020-0445-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 04/10/2020] [Indexed: 12/15/2022] Open
Abstract
In contrast to the previous belief that autoreactive B cells are eliminated from the normal repertoire of B cells, many autoreactive B cells actually escape clonal deletion and develop into mature B cells. These autoreactive B cells in healthy individuals perform some beneficial functions in the host and are homeostatically regulated by regulatory T and B cells or other mechanisms to prevent autoimmune diseases. Autoreactive B-1 cells constitutively produce polyreactive natural antibodies for tissue homeostasis. Recently, autoreactive follicular B cells were reported to participate actively in the germinal center reaction. Furthermore, the selection and usefulness of autoreactive marginal zone (MZ) B cells found in autoimmune diseases are not well understood, although the repertoire of MZ B-cell receptors (BCRs) is presumed to be biased to detect bacterial antigens. In this review, we discuss the autoreactive B-cell populations among all three major B-cell subsets and their regulation in immune responses and diseases.
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9
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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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10
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Satterthwaite AB. Bruton's Tyrosine Kinase, a Component of B Cell Signaling Pathways, Has Multiple Roles in the Pathogenesis of Lupus. Front Immunol 2018; 8:1986. [PMID: 29403475 PMCID: PMC5786522 DOI: 10.3389/fimmu.2017.01986] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 12/21/2017] [Indexed: 01/08/2023] Open
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the loss of adaptive immune tolerance to nucleic acid-containing antigens. The resulting autoantibodies form immune complexes that promote inflammation and tissue damage. Defining the signals that drive pathogenic autoantibody production is an important step in the development of more targeted therapeutic approaches for lupus, which is currently treated primarily with non-specific immunosuppression. Here, we review the contribution of Bruton’s tyrosine kinase (Btk), a component of B and myeloid cell signaling pathways, to disease in murine lupus models. Both gain- and loss-of-function genetic studies have revealed that Btk plays multiple roles in the production of autoantibodies. These include promoting the activation, plasma cell differentiation, and class switching of autoreactive B cells. Small molecule inhibitors of Btk are effective at reducing autoantibody levels, B cell activation, and kidney damage in several lupus models. These studies suggest that Btk may promote end-organ damage both by facilitating the production of autoantibodies and by mediating the inflammatory response of myeloid cells to these immune complexes. While Btk has not been associated with SLE in GWAS studies, SLE B cells display signaling defects in components both upstream and downstream of Btk consistent with enhanced activation of Btk signaling pathways. Taken together, these observations indicate that limiting Btk activity is critical for maintaining B cell tolerance and preventing the development of autoimmune disease. Btk inhibitors, generally well-tolerated and approved to treat B cell malignancy, may thus be a useful therapeutic approach for SLE.
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Affiliation(s)
- Anne B Satterthwaite
- Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, United States.,Department of Immunology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
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11
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Mature lymphoid malignancies: origin, stem cells, and chronicity. Blood Adv 2017; 1:2444-2455. [PMID: 29296894 DOI: 10.1182/bloodadvances.2017008854] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 10/10/2017] [Indexed: 12/15/2022] Open
Abstract
The chronic behavior of mature lymphoid malignancies, with relapses occurring years apart in many patients, has until recently been unexplained. Patterns of relapse also differ vastly between disease entities, with some being highly curable by chemotherapy whereas others are destined to reemerge after treatment. Lately, the use of next-generation sequencing techniques has revealed essential information on the clonal evolution of lymphoid malignancies. Also, experimental xenograft transplantation point to the possible existence of an ancestral (stem) cell. Such a malignant lymphoid stem cell population could potentially evade current therapies and be the cause of chronicity and death in lymphoma patients; however, the evidence is divergent across disease entities and between studies. In this review we present an overview of genetic studies, case reports, and experimental evidence of the source of mature lymphoid malignancy and discuss the perspectives.
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12
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Kim YY, Park KT, Jang SY, Lee KH, Byun JY, Suh KH, Lee YM, Kim YH, Hwang KW. HM71224, a selective Bruton's tyrosine kinase inhibitor, attenuates the development of murine lupus. Arthritis Res Ther 2017; 19:211. [PMID: 28950886 PMCID: PMC5615432 DOI: 10.1186/s13075-017-1402-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 08/01/2017] [Indexed: 01/16/2023] Open
Abstract
Background Systemic lupus erythematosus (SLE) is associated with B cell hyperactivity, and lupus nephritis (LN), in particular, is promoted by the production of autoantibodies and immune complex deposition. Bruton’s tyrosine kinase (BTK) plays critical roles in B cell receptor-related and Fc receptor-related signaling. We aimed to investigate the impact of therapeutic intervention with HM71224 (LY3337641), a selective BTK inhibitor, on the development of murine SLE-like disease features. Methods We examined the therapeutic effects of HM71224 on SLE-like disease features in MRL/lpr and NZB/W F1 mice. The disease-related skin lesion was macroscopically observed in MRL/lpr mice, and the impact on splenomegaly and lymphadenopathy was determined by the weight of the spleen and cervical lymph node. The renal function was evaluated by measuring blood urea nitrogen, serum creatinine, and urine protein, and the renal damage was assessed by histopathological grading. Survival rate was observed during the administration period. The impact of B cell inhibition was investigated in splenocytes from both mice using flow cytometry. Autoantibody was measured in serum by ELISA. Results HM71224 effectively suppressed splenic B220+GL7+, B220+CD138+, and B220+CD69+ B cell counts, and anti-dsDNA IgG and reduced splenomegaly and lymph node enlargement. The compound also prevented skin lesions caused by lupus development, ameliorated renal inflammation and damage with increased blood urea nitrogen and creatinine, and decreased proteinuria. Furthermore, HM71224 also decreased mortality from lupus development in both mouse models. Conclusion Our results indicate that inhibition of BTK by HM71224 effectively reduced B cell hyperactivity and significantly attenuated the development of SLE and LN in rodent SLE models.
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Affiliation(s)
- Yu-Yon Kim
- Host Defense Modulation Lab, College of Pharmacy, Chung-Ang University, 84 Heukseok-Ro, Dongjak-Gu, Seoul, 06974, Republic of Korea.,Hanmi Research Center, Hanmi Pharm. Co. Ltd, 550 Dongtangiheung-Ro, Hwaseong-Si, Gyeonggi-Do, 18469, Republic of Korea
| | - Ki Tae Park
- Hanmi Research Center, Hanmi Pharm. Co. Ltd, 550 Dongtangiheung-Ro, Hwaseong-Si, Gyeonggi-Do, 18469, Republic of Korea
| | - Sun Young Jang
- Hanmi Research Center, Hanmi Pharm. Co. Ltd, 550 Dongtangiheung-Ro, Hwaseong-Si, Gyeonggi-Do, 18469, Republic of Korea
| | - Kyu Hang Lee
- Hanmi Research Center, Hanmi Pharm. Co. Ltd, 550 Dongtangiheung-Ro, Hwaseong-Si, Gyeonggi-Do, 18469, Republic of Korea
| | - Joo-Yun Byun
- Hanmi Research Center, Hanmi Pharm. Co. Ltd, 550 Dongtangiheung-Ro, Hwaseong-Si, Gyeonggi-Do, 18469, Republic of Korea
| | - Kwee Hyun Suh
- Hanmi Research Center, Hanmi Pharm. Co. Ltd, 550 Dongtangiheung-Ro, Hwaseong-Si, Gyeonggi-Do, 18469, Republic of Korea
| | - Young-Mi Lee
- Hanmi Research Center, Hanmi Pharm. Co. Ltd, 550 Dongtangiheung-Ro, Hwaseong-Si, Gyeonggi-Do, 18469, Republic of Korea
| | - Young Hoon Kim
- Hanmi Research Center, Hanmi Pharm. Co. Ltd, 550 Dongtangiheung-Ro, Hwaseong-Si, Gyeonggi-Do, 18469, Republic of Korea.
| | - Kwang Woo Hwang
- Host Defense Modulation Lab, College of Pharmacy, Chung-Ang University, 84 Heukseok-Ro, Dongjak-Gu, Seoul, 06974, Republic of Korea.
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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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14
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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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15
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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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16
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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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18
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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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20
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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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Khan WN, Wright JA, Kleiman E, Boucher JC, Castro I, Clark ES. B-lymphocyte tolerance and effector function in immunity and autoimmunity. Immunol Res 2013; 57:335-53. [DOI: 10.1007/s12026-013-8466-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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22
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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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23
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García-Muñoz R, Roldan Galiacho V, Llorente L. Immunological aspects in chronic lymphocytic leukemia (CLL) development. Ann Hematol 2012; 91:981-96. [PMID: 22526361 PMCID: PMC3368117 DOI: 10.1007/s00277-012-1460-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 03/26/2012] [Indexed: 01/23/2023]
Abstract
Chronic lymphocytic leukemia (CLL) is unique among B cell malignancies in that the malignant clones can be featured either somatically mutated or unmutated IGVH genes. CLL cells that express unmutated immunoglobulin variable domains likely underwent final development prior to their entry into the germinal center, whereas those that express mutated variable domains likely transited through the germinal center and then underwent final development. Regardless, the cellular origin of CLL remains unknown. The aim of this review is to summarize immunological aspects involved in this process and to provide insights about the complex biology and pathogenesis of this disease. We propose a mechanistic hypothesis to explain the origin of B-CLL clones into our current picture of normal B cell development. In particular, we suggest that unmutated CLL arises from normal B cells with self-reactivity for apoptotic bodies that have undergone receptor editing, CD5 expression, and anergic processes in the bone marrow. Similarly, mutated CLL would arise from cells that, while acquiring self-reactivity for autoantigens-including apoptotic bodies-in germinal centers, are also still subject to tolerization mechanisms, including receptor editing and anergy. We believe that CLL is a proliferation of B lymphocytes selected during clonal expansion through multiple encounters with (auto)antigens, despite the fact that they differ in their state of activation and maturation. Autoantigens and microbial pathogens activate BCR signaling and promote tolerogenic mechanisms such as receptor editing/revision, anergy, CD5+ expression, and somatic hypermutation in CLL B cells. The result of these tolerogenic mechanisms is the survival of CLL B cell clones with similar surface markers and homogeneous gene expression signatures. We suggest that both immunophenotypic surface markers and homogenous gene expression might represent the evidence of several attempts to re-educate self-reactive B cells.
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MESH Headings
- Animals
- B-Lymphocytes/immunology
- B-Lymphocytes/metabolism
- B-Lymphocytes/physiology
- Biomarkers, Tumor/analysis
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/physiology
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cell Transformation, Neoplastic/genetics
- Cell Transformation, Neoplastic/immunology
- Gene Expression Profiling
- Humans
- Immune Tolerance/genetics
- Immune Tolerance/physiology
- Leukemia, Lymphocytic, Chronic, B-Cell/diagnosis
- Leukemia, Lymphocytic, Chronic, B-Cell/etiology
- Leukemia, Lymphocytic, Chronic, B-Cell/immunology
- Models, Biological
- Neoplastic Stem Cells/immunology
- Neoplastic Stem Cells/physiology
- Somatic Hypermutation, Immunoglobulin/genetics
- Somatic Hypermutation, Immunoglobulin/physiology
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Affiliation(s)
- Ricardo García-Muñoz
- Hematology Department, Hospital San Pedro, c/Piqueras 98, Logroño, La Rioja, 26006, Spain.
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24
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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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25
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26
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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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27
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Luning Prak ET, Monestier M, Eisenberg RA. B cell receptor editing in tolerance and autoimmunity. Ann N Y Acad Sci 2011; 1217:96-121. [PMID: 21251012 DOI: 10.1111/j.1749-6632.2010.05877.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Receptor editing is the process of ongoing antibody gene rearrangement in a lymphocyte that already has a functional antigen receptor. The expression of a functional antigen receptor will normally terminate further rearrangement (allelic exclusion). However, lymphocytes with autoreactive receptors have a chance at escaping negative regulation by "editing" the specificities of their receptors with additional antibody gene rearrangements. As such, editing complicates the Clonal Selection Hypothesis because edited cells are not simply endowed for life with a single, invariant antigen receptor. Furthermore, if the initial immunoglobulin gene is not inactivated during the editing process, allelic exclusion is violated and the B cell can exhibit two specificities. Here, we describe the discovery of editing, the pathways of receptor editing at the heavy (H) and light (L) chain loci, and current evidence regarding how and where editing happens and what effects it has on the antibody repertoire.
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Affiliation(s)
- Eline T Luning Prak
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
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28
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Abstract
Engagement of the B-cell antigen receptor (BCR) or its precursor, the pre-BCR, induces a cascade of biochemical reactions that regulate the differentiation, selection, survival, and activation of B cells. This cascade is initiated by receptor-associated tyrosine kinases that activate multiple downstream signaling pathways. Since it is required for metabolism, cell growth, development, and survival, the activation of phosphoinositide 3-kinase (PI3K)-dependent pathways represents a crucial event of BCR/pre-BCR signaling. The phosphorylated substrates of the PI3K promote specific recruitment of selected signaling proteins to the plasma membrane, where important signaling complexes are formed to mediate the above-mentioned biological processes. Here, we review the principles of PI3K signaling and highlight the role of an important PI3K-driven module in VDJ recombination of immunoglobulin (Ig) genes during early B-cell development as compared with class switch recombination of Ig genes in mature B cells after activation by specific antigens. Furthermore, we discuss the role of PI3K in the survival of mature B cells, which is strictly dependent on BCR expression and basal BCR signaling.
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Affiliation(s)
- Markus Werner
- Faculty of Biology, Department of Molecular Immunology, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
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29
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Tonic BCR signaling represses receptor editing via Raf- and calcium-dependent signaling pathways. Immunol Lett 2010; 135:74-7. [PMID: 20933008 DOI: 10.1016/j.imlet.2010.09.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 09/27/2010] [Accepted: 09/29/2010] [Indexed: 11/20/2022]
Abstract
Light chain receptor editing is an important mechanism that prevents B cell self-reactivity. We have previously shown that tonic signaling through the BCR represses RAG expression at the immature B cell stage, and that initiation of light chain rearrangements occurs in the absence of these tonic signals in an in vitro model of B cell development. To further test our hypothesis we studied the effect of itpkb deficiency (itpkb(-/-) mice) or Raf hyper-activation (Raf-CAAX transgenic mice), two mutations that enhance BCR signaling, on receptor editing in an in vivo model. This model relies on transferring bone marrow from wild-type or mutant mice into mice expressing an anti-kappa light chain transgene. The anti-kappa transgene induces receptor editing of all kappa light chain expressing B cells, leading to a high frequency of lambda light chain expressing B cells. Anti-κ transgenic recipients of bone marrow from itpkb(-/-) or Raf-CAAX mice showed lower levels of editing to λ light chain than did non-transgenic control recipients. These results provide evidence in an in vivo model that enhanced BCR signaling at the immature B cell stage of development suppresses light chain receptor editing.
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Rowland SL, Leahy KF, Halverson R, Torres RM, Pelanda R. BAFF receptor signaling aids the differentiation of immature B cells into transitional B cells following tonic BCR signaling. THE JOURNAL OF IMMUNOLOGY 2010; 185:4570-81. [PMID: 20861359 DOI: 10.4049/jimmunol.1001708] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BAFF is an important prosurvival cytokine for mature B cells. However, previous studies have shown that BAFFR is already expressed at the immature B cell stage, and that the prosurvival protein Bcl-2 does not completely complement the B cell defects resulting from the absence of BAFFR or BAFF. Thus, we hypothesized that BAFF also functions to aid the differentiation of nonautoreactive immature B cells into transitional B cells and to promote their positive selection. We found that BAFFR is expressed at higher levels on nonautoreactive than on autoreactive immature B cells and that its expression correlates with that of surface IgM and with tonic BCR signaling. Our data indicate that BAFFR signaling enhances the generation of transitional CD23(-) B cells in vitro by increasing cell survival. In vivo, however, BAFFR signaling is dispensable for the generation of CD23(-) transitional B cells in the bone marrow, but it is important for the development of transitional CD23(-) T1 B cells in the spleen. Additionally, we show that BAFF is essential for the differentiation of CD23(-) into CD23(+) transitional B cells both in vitro and in vivo through a mechanism distinct from that mediating cell survival, but requiring tonic BCR signaling. In summary, our data indicate that BAFFR and tonic BCR signals cooperate to enable nonautoreactive immature B cells to differentiate into transitional B cells and to be positively selected into the naive B cell repertoire.
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Affiliation(s)
- Sarah L Rowland
- Integrated Department of Immunology, National Jewish Health and University of Colorado Denver, Denver, CO 80206, USA
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Kövesdi D, Bell SE, Turner M. The development of mature B lymphocytes requires the combined function of CD19 and the p110δ subunit of PI3K. SELF NONSELF 2010; 1:144-153. [PMID: 21487516 DOI: 10.4161/self.1.2.11796] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 02/25/2010] [Accepted: 03/11/2010] [Indexed: 11/19/2022]
Abstract
Mice lacking either CD19 or p110δ have reduced numbers of marginal zone and B1 B cells but normal numbers of naïve B2 cells which occupy the follicles of the lymphoid organs. We show here that mice lacking both CD19 and p110δ have normal B cell development in the bone marrow but have a significant reduction in the number of naïve B2 cells in the bone marrow, spleen and lymph nodes. These p110δ/CD19 double mutant B cells show a survival defect and reduced responsiveness to the pro-survival cytokine BAFF despite normal NFκB2/p100 processing and elevated expression of Bcl-2. Although the combined loss of p110δ and CD19 did not increase switching to Ig-lambda in immature B cells, mature B lymphocytes from the lymph nodes of p110δ/CD19 double mutant mice express highly elevated levels of mRNA encoding RAG-1 and RAG-2, which confirms the existing synergy between CD19 and p110δ-mediated signaling.
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Affiliation(s)
- Dorottya Kövesdi
- Laboratory of Lymphocyte Signalling and Development; The Babraham Institute; Babraham, Cambridge UK
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33
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Abstract
This article focuses on the functions of NF-kappaB that vitally impact lymphocytes and thus adaptive immunity. NF-kappaB has long been known to be essential for many of the responses of mature lymphocytes to invading pathogens. In addition, NF-kappaB has important functions in shaping the immune system so it is able to generate adaptive responses to pathogens. In both contexts, NF-kappaB executes critical cell-autonomous functions within lymphocytes as well as within supportive cells, such as antigen-presenting cells or epithelial cells. It is these aspects of NF-kappaB's physiologic impact that we address in this article.
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Sauerborn M, Schellekens H. B-1 cells and naturally occurring antibodies: influencing the immunogenicity of recombinant human therapeutic proteins? Curr Opin Biotechnol 2009; 20:715-21. [PMID: 19892544 DOI: 10.1016/j.copbio.2009.10.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Accepted: 10/14/2009] [Indexed: 12/18/2022]
Abstract
Recombinant human therapeutic proteins are increasingly being used to treat serious and life-threatening diseases like multiple sclerosis, diabetes mellitus, and cancer. An important side effect of these proteins is the development of antidrug antibodies, which can be neutralizing and thus interfere with the efficacy and safety of the drug. Some biophysical properties, for example, aggregation, also can initiate the immunogenic response to human therapeutics. Many other factors including patients' characteristics may influence this response. Besides induced antibodies, autoantibodies (i.e. naturally occurring antibodies [NAs]) against therapeutic relevant proteins in naïve patients are increasingly being identified. The role of autoreactive B cells and their escape from deletion, production of NAs and their pivotal function in the immune system, the dualistic role of B-1 cells in autoimmunity, and the influence of NAs on disease outcome and their possible impact on the efficacy of human therapeutics will be presented and discussed.
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Affiliation(s)
- Melody Sauerborn
- Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, 3584 CA Utrecht, The Netherlands.
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Cadera EJ, Wan F, Amin RH, Nolla H, Lenardo MJ, Schlissel MS. NF-kappaB activity marks cells engaged in receptor editing. ACTA ACUST UNITED AC 2009; 206:1803-16. [PMID: 19581408 PMCID: PMC2722169 DOI: 10.1084/jem.20082815] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Because of the extreme diversity in immunoglobulin genes, tolerance mechanisms are necessary to ensure that B cells do not respond to self-antigens. One such tolerance mechanism is called receptor editing. If the B cell receptor (BCR) on an immature B cell recognizes self-antigen, it is down-regulated from the cell surface, and light chain gene rearrangement continues in an attempt to edit the autoreactive specificity. Analysis of a heterozygous mutant mouse in which the NF-κB–dependent IκBα gene was replaced with a lacZ (β-gal) reporter complementary DNA (cDNA; IκBα+/lacZ) suggests a potential role for NF-κB in receptor editing. Sorted β-gal+ pre–B cells showed increased levels of various markers of receptor editing. In IκBα+/lacZ reporter mice expressing either innocuous or self-specific knocked in BCRs, β-gal was preferentially expressed in pre–B cells from the mice with self-specific BCRs. Retroviral-mediated expression of a cDNA encoding an IκBα superrepressor in primary bone marrow cultures resulted in diminished germline κ and rearranged λ transcripts but similar levels of RAG expression as compared with controls. We found that IRF4 transcripts were up-regulated in β-gal+ pre–B cells. Because IRF4 is a target of NF-κB and is required for receptor editing, we suggest that NF-κB could be acting through IRF4 to regulate receptor editing.
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Affiliation(s)
- Emily J Cadera
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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Autoimmunity and lymphoma: is mantle cell lymphoma a mistake of the receptor editing mechanism? Leuk Res 2009; 33:1437-9. [PMID: 19523686 DOI: 10.1016/j.leukres.2009.05.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 03/18/2009] [Accepted: 05/12/2009] [Indexed: 11/21/2022]
Abstract
Mantle cell lymphoma (MCL) is an aggressive B cell malignancy, which is believed to originate from naïve B cells in the mantle zone of lymph nodes. We speculate that a possible mechanistic hypothesis for the generation of MCL is one in which receptor editing and germinal centre exclusion could be involved in the molecular development and in the display of clinical characteristics of this rare, aggressive and scarcely understood lymphoma. The hypothesis is supported by a preferential autoimmune related IGVH gene utilization in MCL, where VH3-21, VH4-34 and VH5-51 genes are predominant, and by the fact that MCL expresses immunoglobulin light chain (IgL) lambda more frequently than other non-Hodgkin's lymphomas and that IgL lambda-producing B cells usually delete one or both their IgL kappa genes.
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Henry RA, Acevedo-Suárez CA, Thomas JW. Functional silencing is initiated and maintained in immature anti-insulin B cells. THE JOURNAL OF IMMUNOLOGY 2009; 182:3432-9. [PMID: 19265121 DOI: 10.4049/jimmunol.0803121] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Mechanisms of B cell tolerance act during development in the bone marrow and periphery to eliminate or restrict autoreactive clones to prevent autoimmune disease. B cells in the spleens of mice that harbor anti-insulin BCR transgenes (125Tg) are maintained in a functionally silenced or anergic state by endogenous hormone, but it is not clear when and where anergy is induced. An in vitro bone marrow culture system was therefore used to probe whether small protein hormones, a critical class of autoantigens, could interact with the BCR to induce anergy early during B cell development. Upon exposure to insulin, anti-insulin (125Tg) immature B cells show similar hallmarks of anergy as those observed in mature splenic B cells. These include BCR down-regulation, impaired proliferative responses to anti-CD40, and diminished calcium mobilization upon stimulation with BCR-dependent and independent stimuli. Inhibition of calcineurin also results in reduced immature B cell proliferation in a similar manner, suggesting a potential mechanism through which reduced intracellular calcium mobilization may be altering cellular proliferation. Signs of impairment appear after short-term exposure to insulin, which are reversible upon Ag withdrawal. This suggests that a high degree of functional plasticity is maintained at this stage and that constant Ag engagement is required to maintain functional inactivation. These findings indicate that tolerance observed in mature, splenic 125Tg B cells is initiated by insulin in the developing B cell compartment and thus highlight an important therapeutic window for the prevention of insulin autoimmunity.
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Affiliation(s)
- Rachel A Henry
- Department of Microbiology and Immunology, Vanderbilt University, Nashville, TN 37232, USA
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Mechanisms controlling expression of the RAG locus during lymphocyte development. Curr Opin Immunol 2009; 21:173-8. [PMID: 19359154 DOI: 10.1016/j.coi.2009.03.008] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Accepted: 03/13/2009] [Indexed: 11/20/2022]
Abstract
Recombination activating genes (RAG)1 and RAG2 are expressed in developing B and T lymphocytes and are required for the rearrangement of antigen receptor genes. In turn, RAG expression is regulated by the products of these assembled immunoglobulin (Ig) and T cell receptor (TCR) genes. Upon successful assembly of Ig genes, the antigen receptor is expressed on the immature B cell surface and tested for autoreactivity leading to either maintenance or inactivation of RAG expression. Successful assembly of TCR genes is followed by surface TCR expression and testing for its ability to interact with self-MHC, which if appropriate leads to the inactivation of RAG expression. Recent studies in B and T lymphocytes demonstrate that the reduction in RAG expression at the immature B and double-positive (DP) T cell stages is mediated through tonic (foreign antigen independent) receptor signaling. In B cells, tonic signaling activates PI(3)K and Akt kinases, which phosphorylate and lead to the cytoplasmic sequestration of FoxO proteins, the key transcriptional activators of RAG expression. In T cells, tonic signaling activates Abl and Erk kinases, leading to the transcriptional inactivation of RAGs.
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Hillion S, Rochas C, Youinou P, Jamin C. Signaling pathways regulating RAG expression in B lymphocytes. Autoimmun Rev 2009; 8:599-604. [PMID: 19393209 DOI: 10.1016/j.autrev.2009.02.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2009] [Accepted: 02/04/2009] [Indexed: 10/21/2022]
Abstract
Development of B-cell lymphopoiesis is dependent on the presence of recombination activating genes RAG1 and RAG2 enzymes. They control the rearrangements of immunoglobulin variable, diversity and joining region segments, and allow progression of the cellular maturation. RAG1 and RAG2 are successively up- and down-regulated at each B-cell stage to progressively generate a B-cell receptor for which unforeseeable antigenic specificity results from a stochastic process. Therefore, in autoreactive immature B cells, new round of RAG re-expression can be observed to eliminate self-reactivity. In some circumstances, RAG up-regulation can also be found in peripheral mature B lymphocytes, specifically in autoimmune diseases. It is therefore of utmost importance to unravel signaling pathways that trigger RAG induction in normal and pathological conditions. Therapeutic modulation of cytokines or intracellular contacts involved in RAG expression might restrict the development of inappropriate autoimmune repertoire.
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Panigrahi AK, Goodman NG, Eisenberg RA, Rickels MR, Naji A, Luning Prak ET. RS rearrangement frequency as a marker of receptor editing in lupus and type 1 diabetes. ACTA ACUST UNITED AC 2008; 205:2985-94. [PMID: 19075293 PMCID: PMC2605238 DOI: 10.1084/jem.20082053] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Continued antibody gene rearrangement, termed receptor editing, is an important mechanism of central B cell tolerance that may be defective in some autoimmune individuals. We describe a quantitative assay for recombining sequence (RS) rearrangement that we use to estimate levels of antibody light chain receptor editing in various B cell populations. RS rearrangement is a recombination of a noncoding gene segment in the κ antibody light chain locus. RS rearrangement levels are highest in the most highly edited B cells, and are inappropriately low in autoimmune mouse models of systemic lupus erythematosus (SLE) and type 1 diabetes (T1D), including those without overt disease. Low RS rearrangement levels are also observed in human subjects with SLE or T1D.
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Affiliation(s)
- Anil K Panigrahi
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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