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Wahid AA, Dunphy RW, Macpherson A, Gibson BG, Kulik L, Whale K, Back C, Hallam TM, Alkhawaja B, Martin RL, Meschede I, Laabei M, Lawson ADG, Holers VM, Watts AG, Crennell SJ, Harris CL, Marchbank KJ, van den Elsen JMH. Insights Into the Structure-Function Relationships of Dimeric C3d Fragments. Front Immunol 2021; 12:714055. [PMID: 34434196 PMCID: PMC8381054 DOI: 10.3389/fimmu.2021.714055] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 07/21/2021] [Indexed: 11/13/2022] Open
Abstract
Cleavage of C3 to C3a and C3b plays a central role in the generation of complement-mediated defences. Although the thioester-mediated surface deposition of C3b has been well-studied, fluid phase dimers of C3 fragments remain largely unexplored. Here we show C3 cleavage results in the spontaneous formation of C3b dimers and present the first X-ray crystal structure of a disulphide-linked human C3d dimer. Binding studies reveal these dimers are capable of crosslinking complement receptor 2 and preliminary cell-based analyses suggest they could modulate B cell activation to influence tolerogenic pathways. Altogether, insights into the physiologically-relevant functions of C3d(g) dimers gained from our findings will pave the way to enhancing our understanding surrounding the importance of complement in the fluid phase and could inform the design of novel therapies for immune system disorders in the future.
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Affiliation(s)
- Ayla A. Wahid
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Rhys W. Dunphy
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Alex Macpherson
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
- UCB Pharma, Slough, United Kingdom
| | - Beth G. Gibson
- Translational and Clinical Research Institute, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Liudmila Kulik
- Division of Rheumatology, University of Colorado, Aurora, CO, United States
| | | | - Catherine Back
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Thomas M. Hallam
- Translational and Clinical Research Institute, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Bayan Alkhawaja
- Department of Pharmacy and Pharmacology, University of Bath, Bath, United Kingdom
| | - Rebecca L. Martin
- Department of Pharmacy and Pharmacology, University of Bath, Bath, United Kingdom
| | | | - Maisem Laabei
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | | | - V. Michael Holers
- Division of Rheumatology, University of Colorado, Aurora, CO, United States
| | - Andrew G. Watts
- Department of Pharmacy and Pharmacology, University of Bath, Bath, United Kingdom
- Centre for Therapeutic Innovation, University of Bath, Bath, United Kingdom
| | - Susan J. Crennell
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Claire L. Harris
- Translational and Clinical Research Institute, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Kevin J. Marchbank
- Translational and Clinical Research Institute, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Jean M. H. van den Elsen
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
- Centre for Therapeutic Innovation, University of Bath, Bath, United Kingdom
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2
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Kulik L, Laskowski J, Renner B, Woolaver R, Zhang L, Lyubchenko T, You Z, Thurman JM, Holers VM. Targeting the Immune Complex-Bound Complement C3d Ligand as a Novel Therapy for Lupus. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2019; 203:3136-3147. [PMID: 31732528 PMCID: PMC6900485 DOI: 10.4049/jimmunol.1900620] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 10/21/2019] [Indexed: 11/19/2022]
Abstract
Humoral autoimmunity is central to the development of systemic lupus erythematosus (SLE). Complement receptor type 2 (CR2)/CD21 plays a key role in the development of high-affinity Abs and long-lasting memory to foreign Ags. When CR2 is bound by its primary C3 activation fragment-derived ligand, designated C3d, it coassociates with CD19 on B cells to amplify BCR signaling. C3d and CR2 also mediate immune complex binding to follicular dendritic cells. As the development of SLE involves subversion of normal B cell tolerance checkpoints, one might expect that CR2 ligation by C3d-bound immune complexes would promote development of SLE. However, prior studies in murine models of SLE using gene-targeted Cr2-/- mice, which lack both CR2 and complement receptor 1 (CR1), have demonstrated contradictory results. As a new approach, we developed a highly specific mouse anti-mouse C3d mAb that blocks its interaction with CR2. With this novel tool, we show that disruption of the critical C3d-CR2 ligand-receptor binding step alone substantially ameliorates autoimmunity and renal disease in the MRL/lpr model of SLE.
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Affiliation(s)
- Liudmila Kulik
- Division of Rheumatology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045;
| | - Jennifer Laskowski
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, CO 80045; and
| | - Brandon Renner
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, CO 80045; and
| | - Rachel Woolaver
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, CO 80045; and
| | - Lian Zhang
- Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Taras Lyubchenko
- Division of Rheumatology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Zhiying You
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, CO 80045; and
| | - Joshua M Thurman
- Division of Renal Diseases and Hypertension, University of Colorado Anschutz Medical Campus, Aurora, CO 80045; and
| | - V Michael Holers
- Division of Rheumatology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
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Taylor RL, Cruickshank MN, Karimi M, Ng HL, Quail E, Kaufman KM, Harley JB, Abraham LJ, Tsao BP, Boackle SA, Ulgiati D. Focused transcription from the human CR2/CD21 core promoter is regulated by synergistic activity of TATA and Initiator elements in mature B cells. Cell Mol Immunol 2016; 13:119-31. [PMID: 25640655 PMCID: PMC4711682 DOI: 10.1038/cmi.2014.138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Revised: 12/05/2014] [Accepted: 12/27/2014] [Indexed: 12/13/2022] Open
Abstract
Complement receptor 2 (CR2/CD21) is predominantly expressed on the surface of mature B cells where it forms part of a coreceptor complex that functions, in part, to modulate B-cell receptor signal strength. CR2/CD21 expression is tightly regulated throughout B-cell development such that CR2/CD21 cannot be detected on pre-B or terminally differentiated plasma cells. CR2/CD21 expression is upregulated at B-cell maturation and can be induced by IL-4 and CD40 signaling pathways. We have previously characterized elements in the proximal promoter and first intron of CR2/CD21 that are involved in regulating basal and tissue-specific expression. We now extend these analyses to the CR2/CD21 core promoter. We show that in mature B cells, CR2/CD21 transcription proceeds from a focused TSS regulated by a non-consensus TATA box, an initiator element and a downstream promoter element. Furthermore, occupancy of the general transcriptional machinery in pre-B versus mature B-cell lines correlate with CR2/CD21 expression level and indicate that promoter accessibility must switch from inactive to active during the transitional B-cell window.
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Affiliation(s)
- Rhonda L Taylor
- School of Pathology and Laboratory Medicine, Centre for Genetic Origins of Health and Disease, The University of Western Australia, Crawley, WA, Australia
- Biochemistry and Molecular Biology, School of Chemistry and Biochemistry, The University of Western Australia, Crawley, WA, Australia
| | - Mark N Cruickshank
- Telethon Kids Institute, The University of Western Australia, Crawley, WA, Australia
| | - Mahdad Karimi
- Biochemistry and Molecular Biology, School of Chemistry and Biochemistry, The University of Western Australia, Crawley, WA, Australia
| | - Han Leng Ng
- School of Pathology and Laboratory Medicine, Centre for Genetic Origins of Health and Disease, The University of Western Australia, Crawley, WA, Australia
| | - Elizabeth Quail
- Biochemistry and Molecular Biology, School of Chemistry and Biochemistry, The University of Western Australia, Crawley, WA, Australia
| | - Kenneth M Kaufman
- Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- US Department of Veterans Affairs Medical Center, Cincinnati, OH, USA
| | - John B Harley
- Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- US Department of Veterans Affairs Medical Center, Cincinnati, OH, USA
| | - Lawrence J Abraham
- School of Pathology and Laboratory Medicine, Centre for Genetic Origins of Health and Disease, The University of Western Australia, Crawley, WA, Australia
| | - Betty P Tsao
- Division of Rheumatology, Department of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
| | - Susan A Boackle
- Division of Rheumatology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Daniela Ulgiati
- School of Pathology and Laboratory Medicine, Centre for Genetic Origins of Health and Disease, The University of Western Australia, Crawley, WA, Australia
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Taher TE, Muhammad HA, Rahim A, Flores-Borja F, Renaudineau Y, Isenberg DA, Mageed RA. Aberrant B-lymphocyte responses in lupus: inherent or induced and potential therapeutic targets. Eur J Clin Invest 2013; 43:866-80. [PMID: 23701475 DOI: 10.1111/eci.12111] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 04/29/2013] [Indexed: 12/11/2022]
Abstract
BACKGROUND Lupus is a prototype autoimmune disease of unknown aetiology. The disease is complex; manifest diverse clinical symptoms and disease mechanisms. This complexity has provided many leads to explore: from disease mechanisms to approaches for therapy. B-lymphocytes play a central role in the pathogenesis of the disease. However, the cause of aberrant B-lymphocyte responses in patients and, indeed, its causal relationship with the disease remain unclear. DESIGN This article provides a synopsis of current knowledge of immunological abnormalities in lupus with an emphasis on abnormalities in the B-lymphocyte compartment. RESULTS There is evidence for abnormalities in most compartments of the immune system in animal models and patients with lupus including an ever expanding list of abnormalities within the B-lymphocyte compartment. In addition, recent genome-wide linkage analyses in large cohorts of patients have identified new sets of genetic association factors some with potential links with defective B-lymphocyte responses although their full pathophysiological effects remain to be determined. The accumulating knowledge may help in the identification and application of new targeted therapies for treating lupus disease. CONCLUSIONS Cellular, molecular and genetic studies have provided significant insights into potential causes of immunological defects associated with lupus. Most of this insight relate to defects in B- and T-lymphocyte tolerance, signalling and responses. For B-lymphocytes, there is evidence for altered regulation of inter and intracellular signalling pathways at multiple levels. Some of these abnormalities will be discussed within the context of potential implications for disease pathogenesis and targeted therapies.
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Affiliation(s)
- Taher E Taher
- Bone & Joint Research Unit, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
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Taher TE, Muhammad HA, Bariller E, Flores-Borja F, Renaudineau Y, Isenberg DA, Mageed RA. B-lymphocyte signalling abnormalities and lupus immunopathology. Int Rev Immunol 2013; 32:428-44. [PMID: 23768155 DOI: 10.3109/08830185.2013.788648] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Lupus is a complex autoimmune rheumatic disease of unknown aetiology. The disease is associated with diverse features of immunological abnormality in which B-lymphocytes play a central role. However, the cause of atypical B-lymphocyte responses remains unclear. In this article, we provide a synopsis of current knowledge on intracellular signalling abnormalities in B-lymphocytes in lupus and their potential effects on the response of these cells in mouse models and in patients. There are numerous reported defects in the regulation of intracellular signalling proteins and pathways in B-lymphocytes in lupus that, potentially, affect critical biological responses. Most of the evidence for these defects comes from studies of disease models and genetically engineered mice. However, there is also increasing evidence from studying B-lymphocytes from patients and from genome-wide linkage analyses for parallel defects to those observed in mice. These studies provide molecular and genetic explanations for the key immunological abnormalities associated with lupus. Most of the new information appears to relate to defects in intracellular signalling that impact B-lymphocyte tolerance, cytokine production and responses to infections. Some of these abnormalities will be discussed within the context of disease pathogenesis.
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Affiliation(s)
- Taher E Taher
- Bone & Joint Research Unit, William Harvey Research Institute, Barts
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6
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Thurman JM, Kulik L, Orth H, Wong M, Renner B, Sargsyan SA, Mitchell LM, Hourcade DE, Hannan JP, Kovacs JM, Coughlin B, Woodell AS, Pickering MC, Rohrer B, Holers VM. Detection of complement activation using monoclonal antibodies against C3d. J Clin Invest 2013; 123:2218-30. [PMID: 23619360 DOI: 10.1172/jci65861] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 02/21/2013] [Indexed: 12/21/2022] Open
Abstract
During complement activation the C3 protein is cleaved, and C3 activation fragments are covalently fixed to tissues. Tissue-bound C3 fragments are a durable biomarker of tissue inflammation, and these fragments have been exploited as addressable binding ligands for targeted therapeutics and diagnostic agents. We have generated cross-reactive murine monoclonal antibodies against human and mouse C3d, the final C3 degradation fragment generated during complement activation. We developed 3 monoclonal antibodies (3d8b, 3d9a, and 3d29) that preferentially bind to the iC3b, C3dg, and C3d fragments in solution, but do not bind to intact C3 or C3b. The same 3 clones also bind to tissue-bound C3 activation fragments when injected systemically. Using mouse models of renal and ocular disease, we confirmed that, following systemic injection, the antibodies accumulated at sites of C3 fragment deposition within the glomerulus, the renal tubulointerstitium, and the posterior pole of the eye. To detect antibodies bound within the eye, we used optical imaging and observed accumulation of the antibodies within retinal lesions in a model of choroidal neovascularization (CNV). Our results demonstrate that imaging methods that use these antibodies may provide a sensitive means of detecting and monitoring complement activation-associated tissue inflammation.
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Affiliation(s)
- Joshua M Thurman
- Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado 80045, USA.
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7
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Pappworth IY, Hayes C, Dimmick J, Morgan BP, Holers VM, Marchbank KJ. Mice expressing human CR1/CD35 have an enhanced humoral immune response to T-dependent antigens but fail to correct the effect of premature human CR2 expression. Immunobiology 2011; 217:147-57. [PMID: 21783272 DOI: 10.1016/j.imbio.2011.06.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 06/06/2011] [Accepted: 06/13/2011] [Indexed: 11/19/2022]
Abstract
We have previously demonstrated that mice expressing human complement receptor type 2 (CR2/CD21) during the CD43(+)/CD25(-) late pro-B cell stage of B cell development have marked changes in their subsequent B cell ontogeny. Here, we show that the humoral immune response to the T cell dependent antigen, sheep red blood cells (SRBCs) can be moderately enhanced with the addition of human CR1 (driven by the lambda promoter/enhancer transgene) to endogenous mCR1/CR2 expression on the B cell surface but that hCR1 expression alone (on the mouse CR1/2 deficient background) has no effect on the humoral immune response or general B cell development. Furthermore, expression of hCR1 had no recuperative effect on the markedly altered B cell phenotype noted with premature expression of hCR2 (either in the presence or absence of endogenous mCR1/2). We conclude that hCR1 alone cannot replace the role of CR2 in mice and that the effects of premature hCR2 expression during BCR development are not significantly altered by the addition of hCR1 at that developmental stage or beyond; thus hCR2 signaling in the mouse remains dominant over subsequent input from either hCR1 or endogenous receptors.
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Affiliation(s)
- Isabel Y Pappworth
- Applied Immunobiology and Transplantation, Institute of Cellular Medicine, Newcastle University, Framlington Place, Newcastle-upon-Tyne, UK
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8
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Human complement receptor type 2 (CR2/CD21) transgenic mice provide an in vivo model to study immunoregulatory effects of receptor antagonists. Mol Immunol 2011; 48:883-94. [DOI: 10.1016/j.molimm.2010.12.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 12/16/2010] [Accepted: 12/20/2010] [Indexed: 01/12/2023]
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9
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Twohig JP, Pappworth IY, Sivasankar B, Kulik L, Bull M, Holers VM, Wang EC, Marchbank KJ. Defective B cell ontogeny and humoral immune response in mice prematurely expressing human complement receptor 2 (CR2, CD21) is similar to that seen in aging wild type mice. Mol Immunol 2009; 46:2002-13. [PMID: 19359041 PMCID: PMC2706330 DOI: 10.1016/j.molimm.2009.03.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 03/12/2009] [Accepted: 03/14/2009] [Indexed: 02/03/2023]
Abstract
Mice prematurely expressing human CR2 (hCR2) in the B cell lineage have a defective B cell ontogeny and humoral immune response. We have previously determined altered tyrosine phosphorylation patterns within hCR2 transgenic mice, suggesting that irreversible changes in B cell signaling pathways had occurred, which could explain the B cell unresponsiveness associated with hCR2 transgene expression. In support of that assertion, we found that increasing antigen dose or addition of adjuvant had a minimal impact on the ability of B cells to respond to antigen. However, analysis of aged hCR2high mice (1 year plus) revealed that both B cell numbers, B cell sub-population distribution including expansion of a newly described B regulatory cell subset, and immune responses were comparable with age-matched hCR2 negative mice. Finally, we established that B cell unresponsiveness to antigen in aging wild type mice (1 year plus) was equivalent to that noted in 3-month-old hCR2high mice. This data provides evidence that 3-month-old hCR2high mice have a humoral immune system resembling aged mice and suggests that further examination of the precise molecular and cellular parallells between aged wild type mice and 3-month-old hCR2high mice could provide an important insight into the mechanisms which lead to B cell unresponsiveness in the aging immune system.
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Affiliation(s)
- Jason P. Twohig
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Cardiff, UK
| | - Isabel Y. Pappworth
- Institute of Human Genetics, Newcastle University, Center for Life, Central Parkway, Newcastle NE1 3BZ, UK
| | | | - Liudmila Kulik
- Departments of Medicine and Immunology, University of Colorado, SOM, Denver, CO, USA
| | - Melanie Bull
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Cardiff, UK
| | - V. Michael Holers
- Departments of Medicine and Immunology, University of Colorado, SOM, Denver, CO, USA
| | - Eddie C.Y. Wang
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Cardiff, UK
| | - Kevin J. Marchbank
- Institute of Human Genetics, Newcastle University, Center for Life, Central Parkway, Newcastle NE1 3BZ, UK
- Corresponding author. Tel.: +44 191 222 5998; fax: +44 191 222 8988.
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Pappworth IY, Kulik L, Haluszczak C, Reuter JW, Holers VM, Marchbank KJ. Increased B cell deletion and significantly reduced auto-antibody titre due to premature expression of human complement receptor 2 (CR2, CD21). Mol Immunol 2009; 46:1042-9. [PMID: 19187965 PMCID: PMC2657831 DOI: 10.1016/j.molimm.2008.08.273] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 08/15/2008] [Accepted: 08/18/2008] [Indexed: 02/06/2023]
Abstract
The involvement of complement receptor 2 (CR2) in B cell tolerance and autoimmune disease has been revealed over the past decade or so. Our previous studies have established that mice prematurely expressing human CR2 under the control of a lambda light chain promoter (in particular the hCR2high line) have a marked deficit in their immune response to various antigens and fail to develop collagen-induced arthritis. This phenotype appears to be the result of irreversible changes in B cell signalling pathways and suggested that hCR2 expressing mice are protected from developing autoimmune disease. To test this hypothesis, we examined the ability of the hCR2 to block the development of spontaneous autoimmune disease on the C57BL/6j-Faslpr/Faslpr (B6lpr) background. We found that expression of hCR2 on the B6lpr background resulted in a significant reduction in levels of anti-nuclear antibodies (ANA) generated as mice aged but the levels of ANA were still higher than those found in age matched C57BL/6j (B6) mice. B cells from hCR2high mice were found to display a higher baseline level of apoptosis, whether analysed ex vivo or after in vitro culture, than their B6 counterparts and this was apparently linked to both surface IgM expression by the B cells and C3 levels in the mice. Our data also provides evidence that B cell survival in the presence of hCR2 is heavily modified by the background strain of the mouse. Overall, we have demonstrated that mice expressing hCR2 on their B cells during bone marrow development display a higher degree of apoptosis which may lead to a deletion of autoreactive B cells and be protective against the development of autoimmune disease.
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Affiliation(s)
- Isabel Y. Pappworth
- Institute of Human Genetics, Newcastle University, Central Parkway, Center for Life, Newcastle-upon-Tyne NE1 3BZ, UK
| | - Liudmila Kulik
- Department Medicine and Immunology, University of Colorado Denver, School of Medicine, Aurora, CO 80045, USA
| | - Catherine Haluszczak
- Department Medicine and Immunology, University of Colorado Denver, School of Medicine, Aurora, CO 80045, USA
| | - Jason W. Reuter
- Department Medicine and Immunology, University of Colorado Denver, School of Medicine, Aurora, CO 80045, USA
| | - V. Michael Holers
- Department Medicine and Immunology, University of Colorado Denver, School of Medicine, Aurora, CO 80045, USA
| | - Kevin J. Marchbank
- Institute of Human Genetics, Newcastle University, Central Parkway, Center for Life, Newcastle-upon-Tyne NE1 3BZ, UK
- Corresponding author.
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Lyubchenko T, Nielsen JP, Miller SM, Liubchenko GA, Holers VM. Role of initial protein phosphorylation events and localized release-activated calcium influx in B cell antigen receptor signaling. J Leukoc Biol 2008; 85:298-309. [PMID: 19028960 DOI: 10.1189/jlb.0308193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
An increase in intracellular calcium concentration is one of the major initial steps in B cell activation following antigen receptor (BCR) ligation. We show herein that in C57BL/6 murine B lymphocytes and in model cell lines, BCR-mediated calcium ion (Ca(2+)) influx occurs via highly selective Ca(2+) release-activated channels, and stromal interaction molecule 1 (STIM1) plays an important role in this pathway. We also demonstrate the temporal relation between Ca(2+)-dependent signaling events and formation of the immune synapse. Our data indicate that cytoplasmic Ca(2+) levels in areas adjacent to the immune synapse differ from those in the rest of the cytoplasm. Finally, a comparison of phosphorylation patterns of BCR-triggered signaling proteins in the presence or absence of Ca(2+) revealed the unanticipated finding that initial BCR-triggered, Ca(2+)-dependent tyrosine phosphorylation events involve predominantly Ca(2+) released from intracellular stores and that influx-derived Ca(2+) is not essential. This suggests a different role for this phase of Ca(2+) influx.
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Affiliation(s)
- Taras Lyubchenko
- Department of Medicine and Immunology, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045, USA.
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12
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Pappworth I, Marchbank K. Mice expressing human complement receptor type 1 have an enhanced secondary immune response at the expense of the initial response. Mol Immunol 2008. [DOI: 10.1016/j.molimm.2008.08.141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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13
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Twohig J, Kulik L, Haluszczak C, Reuter J, Rossbach A, Bull M, Holers VM, Marchbank KJ. Defective B cell ontogeny and immune response in human complement receptor 2 (CR2, CD21) transgenic mice is partially recovered in the absence of C3. Mol Immunol 2007; 44:3434-44. [PMID: 17379312 PMCID: PMC1948027 DOI: 10.1016/j.molimm.2007.02.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Revised: 02/12/2007] [Accepted: 02/14/2007] [Indexed: 01/13/2023]
Abstract
Mice prematurely expressing human CR2 (hCR2) in the B cell lineage have a defective B cell ontogeny and immune response. Our recent analysis of this phenotype suggested that signaling through hCR2 and presumably mouse CD19 on the B cell surface, during bone marrow development, could result in the observed changes in B cell function in these mice. To test this hypothesis, we back crossed hCR2(high) transgenic mice onto the CD19(-/-) background. CD19(-/-)hCR2(high) mice were found to possess even fewer mature B cells than their CD19(+/+)hCR2(high) littermates, demonstrating that loss of CD19 exacerbated the effects elicited through hCR2. This data suggests that CD19 provides a survival signal during B cell development in this model. Next, we examined if the removal of the main ligand for CR2, namely C3d, through back-crossing onto the C3(-/-) background could restore normal B cell development. However, we found only minor recovery in peripheral B cell numbers and no obvious change in function. This was despite a three-fold increase in the level of hCR2 expression on B cells isolated from the spleen or bone marrow of C3(-/-)hCR2(high) mice when compared with C3 sufficient littermates. These data demonstrate that hCR2 is integrated in mouse B cell signaling and that the downstream effects of hCR2 expression during early B cell development are partially but not completely due to interaction with C3 fragments and signaling through CD19 in the bone marrow environment.
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Affiliation(s)
- Jason Twohig
- Department of Medical Biochemistry & Immunology, Cardiff University, Heath Park, Cardiff CF14 4XX, UK
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