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George C Tsokos - One of the best experts on this subject based on the ideXlab platform.
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Complement and Autoimmunity
The Complement System, 2020Co-Authors: George C Tsokos, Mate TolnayAbstract:The role of Complement in the regulation of the immune response has been studied extensively (1) and is reviewed elsewhere in this book. At the mature B cell level, Complement 3 products bind to Complement Receptor 2 (CR2) expressed on the surface of B and dendritic cells and facilitate antigen localization and process, lowering the excitation threshold and deferring apoptosis. In this chapter we will discuss the impact of Complement component deficiency in man and mouse on the development of autoimmunity. Differences between mice and humans will become apparent and the dual effect of Complement as effector of tissue pathology and controller of the development of the immune cell repertoire will emerge.
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Complement 3d: from molecular adjuvant to target of immune escape mechanisms.
Clinical Immunology, 2006Co-Authors: Elke S. Bergmann-leitner, Wolfgang W. Leitner, George C TsokosAbstract:C3d is a fragment of the Complement factor C3 and is generated in the course of Complement activation. When bound to antigen in single or multiple copies, the B cell Receptor and Complement Receptor 2 become co-crosslinked resulting in decreased or increased B cell responses depending on the valence of the antigen-C3d construct. When antigen-C3d constructs are used for the purpose of generating a protective immune response (vaccines), they may either enhance the expected response or suppress it depending on the nature of the antigen. Various pathogens use C3d to evade the immune system by inhibiting Complement activation, invading and homing in host cells or masking immunogenic areas of pathogen proteins. Therefore, future vaccination strategies for infectious diseases and cancer employing C3d as a molecular adjuvant need to be carefully evaluated before choosing a target antigen in order to take advantage of the adjuvant effect of the Complement component while avoiding potential vaccine complications associated with immune escape mechanisms.
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anti phospholipid antibodies restore mesenteric ischemia reperfusion induced injury in Complement Receptor 2 Complement Receptor 1 deficient mice
Journal of Immunology, 2004Co-Authors: Ryan Egan, Guillermina Girardi, Jane E Salmon, Michael V Holers, Marc Monestier, Chunyan Chai, Sherry D. Fleming, George C TsokosAbstract:Complement Receptor 2-deficient ( Cr2 −/− ) mice are resistant to mesenteric ischemia/reperfusion (I/R) injury because they lack a component of the natural Ab repertoire. Neither the nature of the Abs that are involved in I/R injury nor the composition of the target Ag, to which recognition is lacking in Cr2 −/− mice, is known. Because anti-phospholipid Abs have been shown to mediate fetal growth retardation and loss when injected into pregnant mice, we performed experiments to determine whether anti-phospholipid Abs can also reconstitute I/R injury and, therefore, represent members of the injury-inducing repertoire that is missing in Cr2 −/− mice. We demonstrate that both murine and human monoclonal and polyclonal Abs against negatively charged phospholipids can reconstitute mesenteric I/R-induced intestinal and lung tissue damage in Cr2 −/− mice. In addition, Abs against β2 glycoprotein I restore local and remote tissue damage in the Cr2 −/− mice. Unlike Cr2 −/− mice, reconstitution of I/R tissue damage in the injury-resistant Rag-1 −/− mouse required the infusion of both anti-β2-glycoprotein I and anti-phospholipid Ab. We conclude that anti-phospholipid Abs can bind to tissues subjected to I/R insult and mediate tissue damage.
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Anti-phospholipid antibodies restore mesenteric ischemia/reperfusion-induced injury in Complement Receptor 2/Complement Receptor 1-deficient mice.
Journal of Immunology, 2004Co-Authors: Sherry D. Fleming, Ryan Egan, Guillermina Girardi, Jane E Salmon, Marc Monestier, Chunyan Chai, V Michael Holers, George C TsokosAbstract:Complement Receptor 2-deficient ( Cr2 −/− ) mice are resistant to mesenteric ischemia/reperfusion (I/R) injury because they lack a component of the natural Ab repertoire. Neither the nature of the Abs that are involved in I/R injury nor the composition of the target Ag, to which recognition is lacking in Cr2 −/− mice, is known. Because anti-phospholipid Abs have been shown to mediate fetal growth retardation and loss when injected into pregnant mice, we performed experiments to determine whether anti-phospholipid Abs can also reconstitute I/R injury and, therefore, represent members of the injury-inducing repertoire that is missing in Cr2 −/− mice. We demonstrate that both murine and human monoclonal and polyclonal Abs against negatively charged phospholipids can reconstitute mesenteric I/R-induced intestinal and lung tissue damage in Cr2 −/− mice. In addition, Abs against β2 glycoprotein I restore local and remote tissue damage in the Cr2 −/− mice. Unlike Cr2 −/− mice, reconstitution of I/R tissue damage in the injury-resistant Rag-1 −/− mouse required the infusion of both anti-β2-glycoprotein I and anti-phospholipid Ab. We conclude that anti-phospholipid Abs can bind to tissues subjected to I/R insult and mediate tissue damage.
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nf κb regulates the expression of the human Complement Receptor 2 gene
Journal of Immunology, 2002Co-Authors: Mate Tolnay, George C Tsokos, Lyudmila A VereshchaginaAbstract:CR2 is a key regulator of the B cell response to Ag. Here we show that NF-κB enhances the expression of the human CR2 gene. Promoter truncation, deletion, and mutagenesis studies indicated a functional role for a consensus NF-κB promoter element, as well as a heterogeneous nuclear ribonucleoprotein D element and an overlapping X box/E box. By supershift analysis, the first two elements bound NF-κB p50 and p65 and heterogeneous nuclear ribonucleoprotein RNP D, respectively. The X box/E box bound regulatory factor X5 and, surprisingly, NF-κB p50 and p65. Overexpression of NF-κB p50 enhanced the activity of the CR2 promoter in B cell lines and primary B cells, suggesting a direct role for NF-κB in regulating promoter activity. Importantly, mutation of the NF-κB element or the X box/E box rendered the promoter unresponsive to NF-κB p50. Using chromatin immunoprecipitation in live B cell lines and primary B cells, we found that NF-κB proteins p50, p65, and c-Rel bound to the genomic promoter at two locations that overlap with the consensus NF-κB element or the X box/E box. Finally, stimuli that activate NF-κB enhanced the activity of the CR2 promoter, and LPS rapidly increased the number of CR2 proteins on the surface of primary B cells. We propose that the NF-κB signaling pathway enhances the expression of the CR2 gene, as a result of NF-κB proteins binding to two CR2 promoter elements. Thus, at the onset of an infection, LPS could sensitize the B cell to Ag by enhancing the level of CR2-costimulatory molecules on the cell surface.
Daniela Ulgiati - One of the best experts on this subject based on the ideXlab platform.
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analysis of tandem e box motifs within human Complement Receptor 2 cr2 cd21 promoter reveals cell specific roles for rp58 e2a usf and localized chromatin accessibility
The International Journal of Biochemistry & Cell Biology, 2015Co-Authors: Mark N Cruickshank, Lawrence J Abraham, Michael V Holers, Rhonda L Taylor, Mahdad Karimi, Emily J Fenwick, J S Dods, Elizabeth A Quail, Daniela UlgiatiAbstract:Abstract Complement Receptor 2 (CR2/CD21) plays an important role in the generation of normal B cell immune responses. As transcription appears to be the prime mechanism via which surface CR2/CD21 expression is controlled, understanding transcriptional regulation of this gene will have broader implications to B cell biology. Here we report opposing, cell-context specific control of CR2/CD21 promoter activity by tandem E-box elements, spaced 22 bp apart and within 70 bp of the transcription initiation site. We have identified E2A and USF transcription factors as binding to the distal and proximal E-box sites respectively in CR2-positive B-cells, at a site that is hypersensitive to restriction enzyme digestion compared to non-expressing K562 cells. However, additional unidentified proteins have also been found to bind these functionally important elements. By utilizing a proteomics approach we have identified a repressor protein, RP58, binding the distal E-box motif. Co-transfection experiments using RP58 overexpression constructs demonstrated a specific 10-fold repression of CR2/CD21 transcriptional activity mediated through the distal E-box repressor element. Taken together, our results indicate that repression of the CR2/CD21 promoter can occur through one of the E-box motifs via recruitment of RP58 and other factors to bring about a silenced chromatin context within CR2/CD21 non-expressing cells.
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Analysis of tandem E-box motifs within human Complement Receptor 2 (CR2/CD21) promoter reveals cell specific roles for RP58, E2A, USF and localized chromatin accessibility.
The International Journal of Biochemistry & Cell Biology, 2015Co-Authors: Mark N Cruickshank, Lawrence J Abraham, V Michael Holers, Rhonda L Taylor, Mahdad Karimi, Emily J Fenwick, J S Dods, Elizabeth A Quail, Daniela UlgiatiAbstract:Abstract Complement Receptor 2 (CR2/CD21) plays an important role in the generation of normal B cell immune responses. As transcription appears to be the prime mechanism via which surface CR2/CD21 expression is controlled, understanding transcriptional regulation of this gene will have broader implications to B cell biology. Here we report opposing, cell-context specific control of CR2/CD21 promoter activity by tandem E-box elements, spaced 22 bp apart and within 70 bp of the transcription initiation site. We have identified E2A and USF transcription factors as binding to the distal and proximal E-box sites respectively in CR2-positive B-cells, at a site that is hypersensitive to restriction enzyme digestion compared to non-expressing K562 cells. However, additional unidentified proteins have also been found to bind these functionally important elements. By utilizing a proteomics approach we have identified a repressor protein, RP58, binding the distal E-box motif. Co-transfection experiments using RP58 overexpression constructs demonstrated a specific 10-fold repression of CR2/CD21 transcriptional activity mediated through the distal E-box repressor element. Taken together, our results indicate that repression of the CR2/CD21 promoter can occur through one of the E-box motifs via recruitment of RP58 and other factors to bring about a silenced chromatin context within CR2/CD21 non-expressing cells.
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transcriptional effects of a lupus associated polymorphism in the 5 untranslated region utr of human Complement Receptor 2 cr2 cd21
Molecular Immunology, 2012Co-Authors: Mark N Cruickshank, Susan A. Boackle, Tim R Mercer, Mahdad Karimi, Rhonda Mason, Emily J Fenwick, Betty P Tsao, Daniela UlgiatiAbstract:Abstract Systemic lupus erythematosus (SLE) is a complex autoimmune disease with a strong genetic component that determines risk. A common three single-nucleotide polymorphism (SNP) haplotype of the Complement Receptor 2 (CR2) gene has been associated with increased risk of SLE ( Wu et al., 2007 , Douglas et al., 2009 ), and a less common haplotype consisting of the major allele at SNP1 and minor alleles at SNP2 and 3 confers protection ( Douglas et al., 2009 ). SNP1 (rs3813946), which is located in the 5′ untranslated region (UTR) of the CR2 gene, altered transcriptional activity of a CR2 promoter–luciferase reporter gene construct transiently transfected into a B cell line ( Wu et al., 2007 ) and had an independent effect in the protective haplotype ( Douglas et al., 2009 ). In this study, we show that this SNP alters transcriptional activity in a transiently transfected non B-cell line as well as in stably transfected cell lines, supporting its relevance in vivo. Furthermore, the allele at this SNP affects chromatin accessibility of the surrounding sequence and transcription factor binding. These data confirm the effects of rs3813946 on CR2 transcription, identifying the 5′ UTR to be a novel regulatory element for the CR2 gene in which variation may alter gene function and modify the development of lupus.
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Transcriptional effects of a lupus-associated polymorphism in the 5′ untranslated region (UTR) of human Complement Receptor 2 (CR2/CD21)
Molecular Immunology, 2012Co-Authors: Mark N Cruickshank, Susan A. Boackle, Tim R Mercer, Mahdad Karimi, Emily J Fenwick, Betty P Tsao, Rhonda L Mason, Daniela UlgiatiAbstract:Abstract Systemic lupus erythematosus (SLE) is a complex autoimmune disease with a strong genetic component that determines risk. A common three single-nucleotide polymorphism (SNP) haplotype of the Complement Receptor 2 (CR2) gene has been associated with increased risk of SLE ( Wu et al., 2007 , Douglas et al., 2009 ), and a less common haplotype consisting of the major allele at SNP1 and minor alleles at SNP2 and 3 confers protection ( Douglas et al., 2009 ). SNP1 (rs3813946), which is located in the 5′ untranslated region (UTR) of the CR2 gene, altered transcriptional activity of a CR2 promoter–luciferase reporter gene construct transiently transfected into a B cell line ( Wu et al., 2007 ) and had an independent effect in the protective haplotype ( Douglas et al., 2009 ). In this study, we show that this SNP alters transcriptional activity in a transiently transfected non B-cell line as well as in stably transfected cell lines, supporting its relevance in vivo. Furthermore, the allele at this SNP affects chromatin accessibility of the surrounding sequence and transcription factor binding. These data confirm the effects of rs3813946 on CR2 transcription, identifying the 5′ UTR to be a novel regulatory element for the CR2 gene in which variation may alter gene function and modify the development of lupus.
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Transcriptional effects of a lupus-associated polymorphism in the 5' untranslated region (UTR) of human Complement Receptor 2 (CR2/CD21).
Molecular immunology, 2012Co-Authors: Mark N Cruickshank, Susan A. Boackle, Mahdad Karimi, Betty P Tsao, Rhonda L Mason, Emily Fenwick, Tim Mercer, Daniela UlgiatiAbstract:Systemic lupus erythematosus (SLE) is a complex autoimmune disease with a strong genetic component that determines risk. A common three single-nucleotide polymorphism (SNP) haplotype of the Complement Receptor 2 (CR2) gene has been associated with increased risk of SLE (Wu et al., 2007; Douglas et al., 2009), and a less common haplotype consisting of the major allele at SNP1 and minor alleles at SNP2 and 3 confers protection (Douglas et al., 2009). SNP1 (rs3813946), which is located in the 5' untranslated region (UTR) of the CR2 gene, altered transcriptional activity of a CR2 promoter-luciferase reporter gene construct transiently transfected into a B cell line (Wu et al., 2007) and had an independent effect in the protective haplotype (Douglas et al., 2009). In this study, we show that this SNP alters transcriptional activity in a transiently transfected non B-cell line as well as in stably transfected cell lines, supporting its relevance in vivo. Furthermore, the allele at this SNP affects chromatin accessibility of the surrounding sequence and transcription factor binding. These data confirm the effects of rs3813946 on CR2 transcription, identifying the 5' UTR to be a novel regulatory element for the CR2 gene in which variation may alter gene function and modify the development of lupus.
Michael V Holers - One of the best experts on this subject based on the ideXlab platform.
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site targeted Complement inhibition by a Complement Receptor 2 conjugated inhibitor mtt30 ameliorates post injury neuropathology in mouse brains
Neuroscience Letters, 2016Co-Authors: Megan C Rich, Michael V Holers, Chesleigh N Keene, Miriam D Neher, Krista Johnson, Zhaoxue Yu, Antoine Ganivet, Philip F StahelAbstract:Abstract Intracerebral Complement activation after severe traumatic brain injury (TBI) leads to a cascade of neuroinflammatory pathological sequelae that propagate host-mediated secondary brain injury and adverse outcomes. There are currently no specific pharmacological agents on the market to prevent or mitigate the development of secondary cerebral insults after TBI. A novel chimeric CR2-fH compound (mTT30) provides targeted inhibition of the alternative Complement pathway at the site of tissue injury. This experimental study was designed to test the neuroprotective effects of mTT30 in a mouse model of closed head injury. The administration of 500 μg mTT30 i.v. at 1 h, 4 h and 24 h after head injury attenuated Complement C3 deposition in injured brains, reduced the extent of neuronal cell death, and decreased post-injury microglial activation, compared to vehicle-injected placebo controls. These data imply that site-targeted alternative pathway Complement inhibition may represent a new promising therapeutic avenue for the future management of severe TBI.
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analysis of tandem e box motifs within human Complement Receptor 2 cr2 cd21 promoter reveals cell specific roles for rp58 e2a usf and localized chromatin accessibility
The International Journal of Biochemistry & Cell Biology, 2015Co-Authors: Mark N Cruickshank, Lawrence J Abraham, Michael V Holers, Rhonda L Taylor, Mahdad Karimi, Emily J Fenwick, J S Dods, Elizabeth A Quail, Daniela UlgiatiAbstract:Abstract Complement Receptor 2 (CR2/CD21) plays an important role in the generation of normal B cell immune responses. As transcription appears to be the prime mechanism via which surface CR2/CD21 expression is controlled, understanding transcriptional regulation of this gene will have broader implications to B cell biology. Here we report opposing, cell-context specific control of CR2/CD21 promoter activity by tandem E-box elements, spaced 22 bp apart and within 70 bp of the transcription initiation site. We have identified E2A and USF transcription factors as binding to the distal and proximal E-box sites respectively in CR2-positive B-cells, at a site that is hypersensitive to restriction enzyme digestion compared to non-expressing K562 cells. However, additional unidentified proteins have also been found to bind these functionally important elements. By utilizing a proteomics approach we have identified a repressor protein, RP58, binding the distal E-box motif. Co-transfection experiments using RP58 overexpression constructs demonstrated a specific 10-fold repression of CR2/CD21 transcriptional activity mediated through the distal E-box repressor element. Taken together, our results indicate that repression of the CR2/CD21 promoter can occur through one of the E-box motifs via recruitment of RP58 and other factors to bring about a silenced chromatin context within CR2/CD21 non-expressing cells.
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biophysical investigations of Complement Receptor 2 cd21 and cr2 ligand interactions reveal amino acid contacts unique to each Receptor ligand pair
Journal of Biological Chemistry, 2010Co-Authors: James M Kovacs, Jonathan P Hannan, Elan Z Eisenmesser, Michael V HolersAbstract:Human Complement Receptor type 2 (CR2 and CD21) is a cell membrane Receptor, with 15 or 16 extracellular short consensus repeats (SCRs), that promotes B lymphocyte responses and bridges innate and acquired immunity. The most distally located SCRs, SCR1–2, mediate the interaction of CR2 with its four known ligands (C3d, EBV gp350, IFNα, and CD23). To ascertain specific interacting residues on CR2, we utilized NMR studies wherein gp350 and IFNα were titrated into 15N-labeled SCR1–2, and chemical shift changes indicative of specific inter-molecular interactions were identified. With backbone assignments made, the chemical shift changes were mapped onto the crystal structure of SCR1–2. With regard to gp350, the binding region of CR2 is primarily focused on SCR1 and the inter-SCR linker, specifically residues Asn11, Arg13, Ala22, Arg28, Ser32, Arg36, Lys41, Lys57, Tyr64, Lys67, Tyr68, Arg83, Gly84, and Arg89. With regard to IFNα, the binding is similar to the CR2-C3d interaction with specific residues being Arg13, Tyr16, Arg28, Ser42, Lys48, Lys50, Tyr68, Arg83, Gly84, and Arg89. We also report thermodynamic properties of each ligand-Receptor pair determined using isothermal titration calorimetry. The CR2-C3d interaction was characterized as a two-mode binding interaction with Kd values of 0.13 and 160 μm, whereas the CR2-gp350 and CR2-IFNα interactions were characterized as single site binding events with affinities of 0.014 and 0.035 μm, respectively. The compilation of chemical binding maps suggests specific residues on CR2 that are uniquely important in each of these three binding interactions.
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targeted inhibition of the Complement alternative pathway with Complement Receptor 2 and factor h attenuates collagen antibody induced arthritis in mice
Journal of Immunology, 2009Co-Authors: Nirmal K. Banda, Magdalena J. Glogowska, Gregory L. Stahl, Brandt Levitt, Joshua M Thurman, Kazue Takahashi, Stephen Tomlinson, William P Arend, Michael V HolersAbstract:The alternative pathway (AP) of Complement is required for the induction of collagen Ab-induced arthritis (CAIA) in mice. The objective of this study was to examine the effect of a recombinant AP inhibitor containing Complement Receptor 2 and factor H (CR2-fH) on CAIA in mice. CR2 binds to tissue-fixed activation fragments of C3, and the linked fH is a potent local inhibitor of the AP. CAIA was induced in C57BL/6 mice by i.p. injections of 4 mAb to type II collagen (CII) on day 0 and LPS on day 3. PBS or CR2-fH (250 or 500 μg) were injected i.p. 15 min after the mAb to CII on day 0 and 15 min after LPS on day 3; the mice were sacrificed on day 10. The disease activity score (DAS) was decreased significantly (p < 0.001) in both groups receiving CR2-fH compared with the PBS. Histology scores for inflammation, pannus, bone damage, and cartilage damage decreased in parallel with the DAS. C3 deposition in the synovium and cartilage was significantly reduced (p < 0.0001) in the mice treated with CR2-fH. In vitro studies with immune complexes containing type II collagen and mAb to CII showed that CR2-fH specifically inhibited the AP with minimal effect on the classical pathway (CP) and no effect on the lectin pathway (LP). The relative potency of CR2-fH in vitro was superior to mAbs to factor B and C5. Thus, CR2-fH specifically targets and inhibits the AP of Complement in vitro and is effective in CAIA in vivo.
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mapping of the c3d ligand binding site on Complement Receptor 2 cr2 cd21 using nuclear magnetic resonance and chemical shift analysis
Journal of Biological Chemistry, 2009Co-Authors: James M Kovacs, Jonathan P Hannan, Elan Z Eisenmesser, Michael V HolersAbstract:Abstract Complement Receptor 2 (CR2, CD21) is a cell membrane protein, with 15 or 16 extracellular short consensus repeats (SCRs), that promotes B lymphocyte responses and bridges innate and acquired immunity. The most distally located SCRs (SCR1-2) mediate the interaction of CR2 with its four known ligands (C3d, Epstein-Barr virus gp350, interferon-α, and CD23). Inhibitory monoclonal antibodies against SCR1-2 block binding of all ligands. To develop ligand-specific inhibitors that would also assist in identifying residues unique to each Receptor-ligand interaction, phage were selected from randomly generated libraries by panning with recombinant SCR1-2, followed by specific ligand-driven elution. Derived peptides were tested by competition ELISA. One peptide, C3dp1 (APQHLSSQYSRT) exhibited ligand-specific inhibition at midmicromolar IC50. C3d was titrated into 15N-labeled SCR1-2, which revealed chemical shift changes indicative of specific intermolecular interactions. With backbone assignments made, the chemical shift changes were mapped onto the crystal structure of SCR1-2. With regard to C3d, the binding surface includes regions of SCR1, SCR2, and the inter-SCR linker, specifically residues Arg13, Tyr16, Arg28, Tyr29, Ser32, Thr34, Lys48, Asp56, Lys57, Tyr68, Arg83, Gly84, Asn101, Asn105, and Ser109. SCR1 and SCR2 demonstrated distinct binding modes. The CR2 binding surface incorporating SCR1 is inconsistent with a previous x-ray CR2-C3d co-crystal analysis but consistent with mutagenesis, x-ray neutron scattering, and inhibitory monoclonal antibody epitope mapping. Titration with C3dp1 yielded chemical shift changes (Arg13, Tyr16, Thr34, Lys48, Asp56, Lys57, Tyr68, Arg83, Gly84, Asn105, and Ser109) overlapping with C3d, indicating that C3dp1 interacts at the same CR2 site as C3d.
Rickard P F Lindblom - One of the best experts on this subject based on the ideXlab platform.
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Complement Receptor 2 is increased in cerebrospinal fluid of multiple sclerosis patients and regulates c3 function
Clinical Immunology, 2016Co-Authors: Rickard P F Lindblom, Shainn Aeinehband, Mikael Strom, Faiez Al Nimer, Kerstin Sandholm, Mohsen Khademi, Bo Nilsson, Fredrik PiehlAbstract:Besides its vital role in immunity, the Complement system also contributes to the shaping of the synaptic circuitry of the brain. We recently described that soluble Complement Receptor 2 (sCR2) is ...
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Complement Receptor 2 is increased in cerebrospinal fluid of multiple sclerosis patients and regulates C3 function.
Clinical immunology (Orlando Fla.), 2016Co-Authors: Rickard P F Lindblom, Shainn Aeinehband, Mikael Strom, Faiez Al Nimer, Kerstin Sandholm, Mohsen Khademi, Bo Nilsson, Fredrik Piehl, Kristina N EkdahlAbstract:Besides its vital role in immunity, the Complement system also contributes to the shaping of the synaptic circuitry of the brain. We recently described that soluble Complement Receptor 2 (sCR2) is part of the nerve injury response in rodents. We here study CR2 in context of multiple sclerosis (MS) and explore the molecular effects of CR2 on C3 activation. Significant increases in sCR2 levels were evident in cerebrospinal fluid (CSF) from both patients with relapsing-remitting MS (n=33; 6.2ng/mL) and secondary-progressive MS (n=9; 7.0ng/mL) as compared to controls (n=18; 4.1ng/mL). Furthermore, CSF sCR2 levels correlated significantly both with CSF C3 and C1q as well as to a disease severity measure. In vitro, sCR2 inhibited the cleavage and down regulation of C3b to iC3b, suggesting that it exerts a modulatory role in Complement activation downstream of C3. These results propose a novel function for CR2/sCR2 in human neuroinflammatory conditions.
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Complement Receptor 2 is up regulated in the spinal cord following nerve root injury and modulates the spinal cord response
Journal of Neuroinflammation, 2015Co-Authors: Rickard P F Lindblom, Mikael Strom, Faiez Al Nimer, Alexander Berg, Shahin Aeinehband, Cecilia A Dominguez, Nada Abdelmagid, Matthias HeinigAbstract:Background Activation of the Complement system has been implicated in both acute and chronic states of neurodegeneration. However, a detailed understanding of this complex network of interacting components is still lacking.
Susan A. Boackle - One of the best experts on this subject based on the ideXlab platform.
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Role of Complement Receptor 2 in the Pathogenesis of Systemic Lupus Erythematosus
Advances in Experimental Medicine and Biology, 2020Co-Authors: Susan A. BoackleAbstract:A number of recent studies have suggested that Complement Receptor type 2 (CR2, CD21) may play a role in the development of systemic autoimmunity. This Receptor, located primarily on B cells and follicular dendritic cells in mice with a broader distribution in humans, binds C3 degradation products that have become covalently bound to antigen or immune complexes in the process of Complement activation. Its role in both normal immune responses as well as systemic autoimmune disease has been supported by studies of mice in which the gene has been knocked out by homologous recombination. Furthermore, it is structurally and functionally altered in the NZM2410 mouse model of lupus, and is a strong candidate gene for lupus susceptibility in this model. Based on its known functions, several mechanisms can be hypothesized to explain its potential role in the pathogenesis of systemic lupus erythematosus.
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Chapter 40 – CR2
The Complement FactsBook, 2020Co-Authors: Susan A. BoackleAbstract:Complement Receptor 2 (CR2) is a member of the regulators of Complement activation family that plays critical roles in normal humoral immune responses and the development of autoimmunity. It has three known protein isoforms in humans and is expressed primarily on mature B cells and follicular dendritic cells. Its expression is regulated in a cell type- and stage-specific developmental pattern using both transcriptional and posttranscriptional mechanisms. A single case of CR2 deficiency has been described in humans, and mice with natural functional polymorphisms and gene-targeted deficiency also exist and share similar phenotypes. Functional polymorphisms in human CR2 have been associated with systemic lupus erythematosus.
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gg 12 altered expression of long noncoding rna is associated with a lupus associated variant in Complement Receptor 2
Lupus science & medicine, 2016Co-Authors: Brendan M Giles, Bryan T Nycz, Susan A. BoackleAbstract:Background Systemic lupus erythematosus is a multisystemic autoimmune disease characterised by the production of autoantibodies to nuclear antigens. We have identified a variant in intron 1 of Complement Receptor 2 (CR2/CD21) that is associated with decreased risk of lupus (rs1876453; Pmeta = 4.2 × 10–4, OR = 0.85). Its effect is strongest in subjects with anti-dsDNA antibodies (case-control Pmeta = 7.6 × 10–7, OR = 0.71; case-only Pmeta1.9 × 10–4, OR = 0.75), suggesting a preferential association with this endophenotype. rs1876453, located 97 nucleotides from the 5’ end of CR2 intron 1, alters the binding of multiple protein complexes, including one containing CTCF, and is associated with increased B cell-specific expression of the adjacent gene, Complement Receptor 1 (CR1/CD35). The transcriptional mechanism connecting these observations remains unclear, and we hypothesised that long noncoding RNA (lncRNA) play a role. Materials and methods cDNA was generated by reverse transcription from RNA purified from the Raji B cell line as well as from human tonsil and spleen, peripheral blood mononuclear cells, and purified primary B cells. PCR was performed using 5’ and 3’ primers that targeted spliced exons from known lncRNA sequences in the intergenic region 5’ of CR2, in the CR2 gene, and in CR1 intron 1. Quantitative PCR of primary B cell transcripts was performed using cDNA transcribed using random primers and MultiScribe reverse transcriptase (Applied Biosystems), customised lncRNA primers and probe that targeted spliced exons, Taqman assays for U6 snRNA and b-actin mRNA, and the Applied Biosystems 7500 Real-Time PCR System. Relative expression levels of lncRNA, normalised to either U6 snRNA (A) or b-actin (B), were calculated using the comparative CT method. P values were determined using a two-tailed Student t test and a p value of Results We confirmed the presence of annotated lncRNAs in the CR2-CR1 genomic region in various cell types. One annotated lncRNA located downstream of rs1876453 in CR2 intron 1 was readily detected in B cells. We determined the allele-specific expression of this lncRNA by quantitative RT-PCR and found that it was ∼3-fold increase in individuals with the minor protective allele at rs1876453 (p = 0.0025 normalised to U6 snRNA and p = 0.0054 normalised to beta-actin). Conclusions Our data suggest that the generation of pathogenic autoantibodies associated with early, active, and severe lupus is modified by expression of a CR2 lncRNA that appears to have long-range effects. Examination of its mechanism and effects may therefore reveal a novel target for the treatment of lupus. Acknowledgements This study was approved by the Colorado Multiple Institutional Review Board (Protocol 06–0501). Funding for this work was provided by: NIH R01 AI070983 NIH K24 AI078004 NIH T32 AR007534 University of Colorado School of Medicine University of Colorado Department of Medicine Charley J. Smyth Endowed Chair for Rheumatology Research
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transcriptional effects of a lupus associated polymorphism in the 5 untranslated region utr of human Complement Receptor 2 cr2 cd21
Molecular Immunology, 2012Co-Authors: Mark N Cruickshank, Susan A. Boackle, Tim R Mercer, Mahdad Karimi, Rhonda Mason, Emily J Fenwick, Betty P Tsao, Daniela UlgiatiAbstract:Abstract Systemic lupus erythematosus (SLE) is a complex autoimmune disease with a strong genetic component that determines risk. A common three single-nucleotide polymorphism (SNP) haplotype of the Complement Receptor 2 (CR2) gene has been associated with increased risk of SLE ( Wu et al., 2007 , Douglas et al., 2009 ), and a less common haplotype consisting of the major allele at SNP1 and minor alleles at SNP2 and 3 confers protection ( Douglas et al., 2009 ). SNP1 (rs3813946), which is located in the 5′ untranslated region (UTR) of the CR2 gene, altered transcriptional activity of a CR2 promoter–luciferase reporter gene construct transiently transfected into a B cell line ( Wu et al., 2007 ) and had an independent effect in the protective haplotype ( Douglas et al., 2009 ). In this study, we show that this SNP alters transcriptional activity in a transiently transfected non B-cell line as well as in stably transfected cell lines, supporting its relevance in vivo. Furthermore, the allele at this SNP affects chromatin accessibility of the surrounding sequence and transcription factor binding. These data confirm the effects of rs3813946 on CR2 transcription, identifying the 5′ UTR to be a novel regulatory element for the CR2 gene in which variation may alter gene function and modify the development of lupus.
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Transcriptional effects of a lupus-associated polymorphism in the 5′ untranslated region (UTR) of human Complement Receptor 2 (CR2/CD21)
Molecular Immunology, 2012Co-Authors: Mark N Cruickshank, Susan A. Boackle, Tim R Mercer, Mahdad Karimi, Emily J Fenwick, Betty P Tsao, Rhonda L Mason, Daniela UlgiatiAbstract:Abstract Systemic lupus erythematosus (SLE) is a complex autoimmune disease with a strong genetic component that determines risk. A common three single-nucleotide polymorphism (SNP) haplotype of the Complement Receptor 2 (CR2) gene has been associated with increased risk of SLE ( Wu et al., 2007 , Douglas et al., 2009 ), and a less common haplotype consisting of the major allele at SNP1 and minor alleles at SNP2 and 3 confers protection ( Douglas et al., 2009 ). SNP1 (rs3813946), which is located in the 5′ untranslated region (UTR) of the CR2 gene, altered transcriptional activity of a CR2 promoter–luciferase reporter gene construct transiently transfected into a B cell line ( Wu et al., 2007 ) and had an independent effect in the protective haplotype ( Douglas et al., 2009 ). In this study, we show that this SNP alters transcriptional activity in a transiently transfected non B-cell line as well as in stably transfected cell lines, supporting its relevance in vivo. Furthermore, the allele at this SNP affects chromatin accessibility of the surrounding sequence and transcription factor binding. These data confirm the effects of rs3813946 on CR2 transcription, identifying the 5′ UTR to be a novel regulatory element for the CR2 gene in which variation may alter gene function and modify the development of lupus.