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Ronald P Taylor - One of the best experts on this subject based on the ideXlab platform.
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the Complement receptor 2 factor h fusion protein tt30 protects paroxysmal nocturnal hemoglobinuria erythrocytes from Complement mediated hemolysis and c3 fragment opsonization
Blood, 2012Co-Authors: Antonio M Risitano, Caterina Pascariello, Luigi Del Vecchio, Christopher J Horvath, Masha Fridkishareli, Carmine Selleri, Margaret A Lindorfer, M Sica, Rosario Notaro, Ronald P TaylorAbstract:Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by Complement-mediated intravascular hemolysis because of the lack from erythrocyte surface of the Complement regulators CD55 and CD59, with subsequent uncontrolled continuous spontaneous activation of the Complement Alternative Pathway (CAP), and at times of the Complement classic Pathway. Here we investigate in an in vitro model the effect on PNH erythrocytes of a novel therapeutic strategy for membrane-targeted delivery of a CAP inhibitor. TT30 is a 65 kDa recombinant human fusion protein consisting of the iC3b/C3d-binding region of Complement receptor 2 (CR2) and the inhibitory domain of the CAP regulator factor H (fH). TT30 completely inhibits in a dose-dependent manner hemolysis of PNH erythrocytes in a modified extended acidified serum assay, and also prevents C3 fragment deposition on surviving PNH erythrocytes. The efficacy of TT30 derives from its direct binding to PNH erythrocytes; if binding to the erythrocytes is disrupted, only partial inhibition of hemolysis is mediated by TT30 in solution, which is similar to that produced by the fH moiety of TT30 alone, or by intact human fH. TT30 is a membrane-targeted selective CAP inhibitor that may prevent both intravascular and C3-mediated extravascular hemolysis of PNH erythrocytes and warrants consideration for the treatment of PNH patients.
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the recombinant human Complement receptor 2 factor h fusion protein tt30 protects paroxysmal nocturnal hemoglobinuria erythrocytes from both Complement mediated hemolysis and c3 fragment opsonization
Blood, 2012Co-Authors: Antonio M Risitano, Caterina Pascariello, Luigi Del Vecchio, Christopher J Horvath, Masha Fridkishareli, Carmine Selleri, Margaret A Lindorfer, M Sica, Rosario Notaro, Ronald P TaylorAbstract:Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by Complement-mediated intravascular hemolysis due to the lack from erythrocyte surface of the Complement regulators CD55 and CD59, with subsequent uncontrolled continuous spontaneous activation of the Complement Alternative Pathway (CAP) and, at times, of the Complement classical Pathway. Here we investigate in an in vitro model the effect on PNH erythrocytes of a novel therapeutic strategy for membrane-targeted delivery of a CAP inhibitor. TT30 is a 65 kDa recombinant human fusion protein consisting of the iC3b/C3d-binding region of Complement receptor 2 (CR2) and the inhibitory domain of the CAP regulator factor H (fH). TT30 completely inhibits in a dose-dependent manner hemolysis of PNH erythrocytes in a modified extended acidified serum assay, and also prevents C3 fragment deposition on surviving PNH erythrocytes. The efficacy of TT30 derives from its direct binding to PNH erythrocytes; if binding to the erythrocytes is disrupted, only partial inhibition of hemolysis is mediated by TT30 in solution, which is similar to that produced by the fH moiety of TT30 alone, or by intact human fH. TT30 is a membrane-targeted selective CAP inhibitor that may prevent both intravascular and C3-mediated extravascular hemolysis of PNH erythrocytes and warrants consideration for the treatment of PNH patients.
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hematin promotes Complement Alternative Pathway mediated deposition of c3 activation fragments on human erythrocytes potential implications for the pathogenesis of anemia in malaria
Journal of Immunology, 2007Co-Authors: Andrew W Pawluczkowycz, Margaret A Lindorfer, John N Waitumbi, Ronald P TaylorAbstract:Childhood malaria caused by Plasmodium falciparum is often characterized by severe anemia at low parasite burdens; the mechanism(s) responsible for this pathology remain to be defined. We have reported, based on clinical observations and in vitro models, that Complement control proteins on erythrocytes such as CR1, the immune adherence receptor specific for C3b, may be reduced in childhood malaria, suggesting a possible role for Complement in erythrocyte destruction. Intravascular lysis of iE by P. falciparum leads to release of erythrocyte breakdown products such as hemoglobin and hematin, which have inflammatory properties. In the present article, we demonstrate that in serum and in anticoagulated whole blood, moderate concentrations of hematin activate the Alternative Pathway of Complement and promote deposition of C3 activation and breakdown products on erythrocytes. The degree of C3 fragment deposition is directly correlated with erythrocyte CR1 levels, and erythrocytes opsonized with large amounts of C3dg form rosettes with Raji cells, which express CR2, the C3dg receptor which is expressed on several types of B cells in the spleen. Thus, the reaction mediated by hematin promotes opsonization and possible clearance of the youngest (highest CR1) erythrocytes. A mAb specific for C3b, previously demonstrated to inhibit the Alternative Pathway of Complement, completely blocks the C3 fragment deposition reaction. Use of this mAb in nonhuman primate models of malaria may provide insight into mechanisms of erythrocyte destruction and thus aid in the development of targeted therapies based on inhibiting the Alternative Pathway of Complement.
Antonio M Risitano - One of the best experts on this subject based on the ideXlab platform.
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Toward Complement inhibition 2.0: Next generation antiComplement agents for paroxysmal nocturnal hemoglobinuria.
American journal of hematology, 2018Co-Authors: Antonio M Risitano, Serena MarottaAbstract:Therapeutic Complement inhibition by eculizumab has revolutionized the treatment of paroxysmal nocturnal hemoglobinuria (PNH) with a major impact on its natural history. Nevertheless, emerging unmet clinical needs may benefit from the development of novel Complement inhibitors. Novel strategies of Complement inhibition exploit different agents targeting C5, as well as compound intercepting the Complement cascade at the level of its key component C3, or even upstream at the level of components involved in Complement Alternative Pathway initiation. Many of these agents are already in their clinical development; preliminary data together with a deep understanding of PNH biology may help to anticipate their possible clinical effect. Novel anti-C5 agents include monoclonal antibodies (even long-lasting) as well as other small molecules bioavailable by subcutaneous administration; an anti-C5 small interfering RNA has been developed too. All these anti-C5 agents seem to recapitulate safety and efficacy of current eculizumab treatment; their main improvement pertains to better patient's convenience due to longer dosing interval and/or possible subcutaneous self-administration. The possibility of achieving a deeper C5 inhibition has been shown as well, but its actual clinical meaning remains to be elucidated. Upstream Complement inhibitors include the anti-C3 small peptide compstatin (and its derivatives), and small inhibitors of Complement factor D or Complement factor B. This class of compounds anticipates a possible efficacy in prevention of C3-mediated extravascular hemolysis, in addition to inhibition of intravascular hemolysis, eventually leading to improved hematological responses. The availability of all these compounds will result soon in a substantial improvement of PNH management.
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the Complement receptor 2 factor h fusion protein tt30 protects paroxysmal nocturnal hemoglobinuria erythrocytes from Complement mediated hemolysis and c3 fragment opsonization
Blood, 2012Co-Authors: Antonio M Risitano, Caterina Pascariello, Luigi Del Vecchio, Christopher J Horvath, Masha Fridkishareli, Carmine Selleri, Margaret A Lindorfer, M Sica, Rosario Notaro, Ronald P TaylorAbstract:Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by Complement-mediated intravascular hemolysis because of the lack from erythrocyte surface of the Complement regulators CD55 and CD59, with subsequent uncontrolled continuous spontaneous activation of the Complement Alternative Pathway (CAP), and at times of the Complement classic Pathway. Here we investigate in an in vitro model the effect on PNH erythrocytes of a novel therapeutic strategy for membrane-targeted delivery of a CAP inhibitor. TT30 is a 65 kDa recombinant human fusion protein consisting of the iC3b/C3d-binding region of Complement receptor 2 (CR2) and the inhibitory domain of the CAP regulator factor H (fH). TT30 completely inhibits in a dose-dependent manner hemolysis of PNH erythrocytes in a modified extended acidified serum assay, and also prevents C3 fragment deposition on surviving PNH erythrocytes. The efficacy of TT30 derives from its direct binding to PNH erythrocytes; if binding to the erythrocytes is disrupted, only partial inhibition of hemolysis is mediated by TT30 in solution, which is similar to that produced by the fH moiety of TT30 alone, or by intact human fH. TT30 is a membrane-targeted selective CAP inhibitor that may prevent both intravascular and C3-mediated extravascular hemolysis of PNH erythrocytes and warrants consideration for the treatment of PNH patients.
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the recombinant human Complement receptor 2 factor h fusion protein tt30 protects paroxysmal nocturnal hemoglobinuria erythrocytes from both Complement mediated hemolysis and c3 fragment opsonization
Blood, 2012Co-Authors: Antonio M Risitano, Caterina Pascariello, Luigi Del Vecchio, Christopher J Horvath, Masha Fridkishareli, Carmine Selleri, Margaret A Lindorfer, M Sica, Rosario Notaro, Ronald P TaylorAbstract:Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by Complement-mediated intravascular hemolysis due to the lack from erythrocyte surface of the Complement regulators CD55 and CD59, with subsequent uncontrolled continuous spontaneous activation of the Complement Alternative Pathway (CAP) and, at times, of the Complement classical Pathway. Here we investigate in an in vitro model the effect on PNH erythrocytes of a novel therapeutic strategy for membrane-targeted delivery of a CAP inhibitor. TT30 is a 65 kDa recombinant human fusion protein consisting of the iC3b/C3d-binding region of Complement receptor 2 (CR2) and the inhibitory domain of the CAP regulator factor H (fH). TT30 completely inhibits in a dose-dependent manner hemolysis of PNH erythrocytes in a modified extended acidified serum assay, and also prevents C3 fragment deposition on surviving PNH erythrocytes. The efficacy of TT30 derives from its direct binding to PNH erythrocytes; if binding to the erythrocytes is disrupted, only partial inhibition of hemolysis is mediated by TT30 in solution, which is similar to that produced by the fH moiety of TT30 alone, or by intact human fH. TT30 is a membrane-targeted selective CAP inhibitor that may prevent both intravascular and C3-mediated extravascular hemolysis of PNH erythrocytes and warrants consideration for the treatment of PNH patients.
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design and development of tt30 a novel c3d targeted c3 c5 convertase inhibitor for treatment of human Complement Alternative Pathway mediated diseases
Blood, 2011Co-Authors: Masha Fridkishareli, Christopher J Horvath, Antonio M Risitano, Michael V Holers, Michael Storek, Ante S Lundberg, Istvan MazsaroffAbstract:To selectively modulate human Complement Alternative Pathway (CAP) activity implicated in a wide range of acute and chronic inflammatory conditions and to provide local cell surface and tissue-based inhibition of Complement-induced damage, we developed TT30, a novel therapeutic fusion protein linking the human Complement receptor type 2 (CR2/CD21) C3 fragment (C3frag = iC3b, C3dg, C3d)-binding domain with the CAP inhibitory domain of human factor H (fH). TT30 efficiently blocks ex vivo CAP-dependent C3frag accumulation on activated surfaces, membrane attack complex (MAC) formation and hemolysis of RBCs in a CR2-dependent manner, and with a ∼ 150-fold potency gain over fH, without interference of C3 activation or MAC formation through the classic and lectin Pathways. TT30 protects RBCs from hemolysis and remains bound and detectable for at least 24 hours. TT30 selectively inhibits CAP in cynomolgus monkeys and is bioavailable after subcutaneous injection. Using a unique combination of targeting and effector domains, TT30 controls cell surface CAP activation and has substantial potential utility for the treatment of human CAP-mediated diseases.
Veronique Fremeauxbacchi - One of the best experts on this subject based on the ideXlab platform.
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c3 glomerulopathy understanding a rare Complement driven renal disease
Nature Reviews Nephrology, 2019Co-Authors: Richard J H Smith, Veronique Fremeauxbacchi, Fadi Fakhouri, David J. Kavanagh, Terence H Cook, Gerald B Appel, Anna M Blom, Vivette D Dagati, Mihaly Jozsi, John D LambrisAbstract:The C3 glomerulopathies are a group of rare kidney diseases characterized by Complement dysregulation occurring in the fluid phase and in the glomerular microenvironment, which results in prominent Complement C3 deposition in kidney biopsy samples. The two major subgroups of C3 glomerulopathy - dense deposit disease (DDD) and C3 glomerulonephritis (C3GN) - have overlapping clinical and pathological features suggestive of a disease continuum. Dysregulation of the Complement Alternative Pathway is fundamental to the manifestations of C3 glomerulopathy, although terminal Pathway dysregulation is also common. Disease is driven by acquired factors in most patients - namely, autoantibodies that target the C3 or C5 convertases. These autoantibodies drive Complement dysregulation by increasing the half-life of these vital but normally short-lived enzymes. Genetic variation in Complement-related genes is a less frequent cause. No disease-specific treatments are available, although immunosuppressive agents and terminal Complement Pathway blockers are helpful in some patients. Unfortunately, no treatment is universally effective or curative. In aggregate, the limited data on renal transplantation point to a high risk of disease recurrence (both DDD and C3GN) in allograft recipients. Clinical trials are underway to test the efficacy of several first-generation drugs that target the Alternative Complement Pathway.
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statistical validation of rare Complement variants provides insights into the molecular basis of atypical hemolytic uremic syndrome and c3 glomerulopathy
Journal of Immunology, 2018Co-Authors: Amy J Osborne, Marina Noris, Veronique Fremeauxbacchi, David J. Kavanagh, Matteo Breno, Nicolo Borsa, Daniel P Gale, Lambertus P Van Den Heuvel, Sheila PintoAbstract:Atypical hemolytic uremic syndrome (aHUS) and C3 glomerulopathy (C3G) are associated with dysregulation and overactivation of the Complement Alternative Pathway. Typically, gene analysis for aHUS and C3G is undertaken in small patient numbers, yet it is unclear which genes most frequently predispose to aHUS or C3G. Accordingly, we performed a six-center analysis of 610 rare genetic variants in 13 mostly Complement genes (CFH, CFI, CD46, C3, CFB, CFHR1, CFHR3, CFHR4, CFHR5, CFP, PLG, DGKE, and THBD) from >3500 patients with aHUS and C3G. We report 371 novel rare variants (RVs) for aHUS and 82 for C3G. Our new interactive Database of Complement Gene Variants was used to extract allele frequency data for these 13 genes using the Exome Aggregation Consortium server as the reference genome. For aHUS, significantly more protein-altering rare variation was found in five genes CFH, CFI, CD46, C3, and DGKE than in the Exome Aggregation Consortium (allele frequency < 0.01%), thus correlating these with aHUS. For C3G, an association was only found for RVs in C3 and the N-terminal C3b-binding or C-terminal nonsurface-associated regions of CFH In conclusion, the RV analyses showed nonrandom distributions over the affected proteins, and different distributions were observed between aHUS and C3G that clarify their phenotypes.
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loss of dgke induces endothelial cell activation and death independently of Complement activation
Blood, 2015Co-Authors: Sarah Bruneau, Lubka T Roumenina, Veronique Fremeauxbacchi, Melanie Neel, Marie Frimat, Laetitia Laurent, Fadi FakhouriAbstract:Atypical hemolytic uremic syndrome (aHUS) is classically described to result from a dysregulation of the Complement Alternative Pathway, leading to glomerular endothelial cell (EC) damage and thrombosis. However, recent findings in families with aHUS of mutations in the DGKE gene, which is not an
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Alternative Complement Pathway assessment in patients with atypical hus
Journal of Immunological Methods, 2011Co-Authors: Lubka T Roumenina, Lise Halbwachsmecarelli, Chantal Loirat, Marieagnes Dragondurey, Catherine Sautesfridman, Veronique FremeauxbacchiAbstract:The atypical Hemolytic Uremic Syndrome (aHUS) is a rare thrombotic microangiopathy leading to end stage renal disease in approximately 60% of patients. Over the last decade, a clear link has been demonstrated between this disease and defective Complement regulation. The hallmark of the aHUS is the association with mutations in Complement Alternative Pathway genes. Endothelial damage is related to Complement dysregulation, but the exact mechanism is just starting to be elucidated. Screening for and characterization of mutations in the components of the C3 convertase (C3 and FB) or its regulators (FH, FI, MCP, and Thrombomodulin) or anti-FH antibodies has become an indispensable part of the disease's diagnostic. This review will initially summarize current knowledge on the understanding of Complement activation and regulation, followed by a description on the genetic analysis as well as the methods used for Complement protein quantification. Another part of this review will focus on the mechanisms of action of aHUS-associated mutations. We will emphasize on when and why some mutations lead to protein deficiency, while others result in — to dysfunctional but normally expressed proteins. Finally, we will discuss how the therapy of aHUS patients can be modified according to the functional consequences of each particular genetic defect.
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Complement Alternative Pathway acts as a positive feedback amplification of neutrophil activation
Blood, 2011Co-Authors: Laurent Camous, Lubka T Roumenina, Soumeya Brachemi, Veronique Fremeauxbacchi, Philippe Lesavre, Sylvain Bigot, Lise HalbwachsmecarelliAbstract:Complement Alternative Pathway plays an important, but not clearly understood, role in neutrophil-mediated diseases. We here show that neutrophils themselves activate Complement when stimulated by cytokines or coagulation-derived factors. In whole blood, tumor necrosis factor/formyl-methionyl-leucyl-phenylalanine or phorbol myristate acetate resulted in C3 fragments binding on neutrophils and monocytes, but not on T cells. Neutrophils, stimulated by tumor necrosis factor, triggered the Alternative Pathway on their surface in normal and C2-depleted, but not in factor B-depleted serum and on incubation with purified C3, factors B and D. This occurred independently of neutrophil proteases, oxidants, or apoptosis. Neutrophil-secreted properdin was detected on the cell surface and could focus “in situ” the Alternative Pathway activation. Importantly, Complement, in turn, led to further activation of neutrophils, with enhanced CD11b expression and oxidative burst. Complement-induced neutrophil activation involved mostly C5a and possibly C5b-9 complexes, detected on tumor necrosis factor- and serum-activated neutrophils. In conclusion, neutrophil stimulation by cytokines results in an unusual activation of autologous Complement by healthy cells. This triggers a new amplification loop in physiologic innate immunity: Neutrophils activate the Alternative Complement Pathway and release C5 fragments, which further amplify neutrophil proinflammatory responses. This mechanism, possibly required for effective host defense, may be relevant to Complement involvement in neutrophil-mediated diseases.
Masha Fridkishareli - One of the best experts on this subject based on the ideXlab platform.
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the human Complement receptor type 2 cr2 cr1 fusion protein tt32 a novel targeted inhibitor of the classical and Alternative Pathway c3 convertases prevents arthritis in active immunization and passive transfer mouse models
Molecular Immunology, 2019Co-Authors: Masha Fridkishareli, Michael Storek, Eran Or, Richard Altman, Suresh Katti, Tao Peng, Jeff Hunter, Krista Johnson, Yi Wang, Ante S LundbergAbstract:Abstract Complement activation in human diseases is characterized by the local covalent deposition of the long-lived C3 fragments iC3b/C3dg/C3d. Previously, TT30, a Complement Alternative Pathway (AP)-selective inhibitor, was designed as a fusion protein linking the first four short consensus repeats (SCRs) of human Complement receptor type 2 (CR2) with the first five SCRs of human factor H (fH). TT30 acts by utilizing CR2 SCR1–4 to bind the initially formed iC3b/C3dg/C3d fragments and delivering surface-targeted inhibition of AP C3 and C5 convertases through fH SCR 1-5. In order to combine classical (CP) and lectin (LP) Pathway inhibitory abilities employing CR2-mediated targeting, TT32 was developed. TT32 is a CR2-CR1 fusion protein using the first ten SCRs of CR1, chosen because they contain both C3 and C5 convertase inhibitory activity through utilization of decay-acceleration and cofactor activity for both AP and CP. In Wieslab assays, TT32 showed potent inhibition of the CP and AP with IC50 of 11 and 46 nM, respectively. The TT32 inhibitory activity is partially blocked with a molar excess of a competing anti-CR2 mAb, thus demonstrating the importance of the CR2 targeting. TT32 was studied in the type II (CII) collagen-induced arthritis (CIA), an active immunization model, and the CII antibody-induced arthritis (CAIA) passive transfer model. In CIA, injection of 2.0 mg TT32 at day 21 and 28 post disease induction, but not untargeted CR1 alone, resulted in a 51.5% decrease in clinical disease activity (CDA). In CAIA, treatment with TT32 resulted in a 47.4% decrease in CDA. Therefore, a Complement inhibitor that targets both the AP and CP/LP C3/C5 convertases was shown to limit Complement-mediated tissue damage and inflammation in disease models in which all three Complement activation Pathways are implicated.
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the Complement receptor 2 factor h fusion protein tt30 protects paroxysmal nocturnal hemoglobinuria erythrocytes from Complement mediated hemolysis and c3 fragment opsonization
Blood, 2012Co-Authors: Antonio M Risitano, Caterina Pascariello, Luigi Del Vecchio, Christopher J Horvath, Masha Fridkishareli, Carmine Selleri, Margaret A Lindorfer, M Sica, Rosario Notaro, Ronald P TaylorAbstract:Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by Complement-mediated intravascular hemolysis because of the lack from erythrocyte surface of the Complement regulators CD55 and CD59, with subsequent uncontrolled continuous spontaneous activation of the Complement Alternative Pathway (CAP), and at times of the Complement classic Pathway. Here we investigate in an in vitro model the effect on PNH erythrocytes of a novel therapeutic strategy for membrane-targeted delivery of a CAP inhibitor. TT30 is a 65 kDa recombinant human fusion protein consisting of the iC3b/C3d-binding region of Complement receptor 2 (CR2) and the inhibitory domain of the CAP regulator factor H (fH). TT30 completely inhibits in a dose-dependent manner hemolysis of PNH erythrocytes in a modified extended acidified serum assay, and also prevents C3 fragment deposition on surviving PNH erythrocytes. The efficacy of TT30 derives from its direct binding to PNH erythrocytes; if binding to the erythrocytes is disrupted, only partial inhibition of hemolysis is mediated by TT30 in solution, which is similar to that produced by the fH moiety of TT30 alone, or by intact human fH. TT30 is a membrane-targeted selective CAP inhibitor that may prevent both intravascular and C3-mediated extravascular hemolysis of PNH erythrocytes and warrants consideration for the treatment of PNH patients.
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the recombinant human Complement receptor 2 factor h fusion protein tt30 protects paroxysmal nocturnal hemoglobinuria erythrocytes from both Complement mediated hemolysis and c3 fragment opsonization
Blood, 2012Co-Authors: Antonio M Risitano, Caterina Pascariello, Luigi Del Vecchio, Christopher J Horvath, Masha Fridkishareli, Carmine Selleri, Margaret A Lindorfer, M Sica, Rosario Notaro, Ronald P TaylorAbstract:Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by Complement-mediated intravascular hemolysis due to the lack from erythrocyte surface of the Complement regulators CD55 and CD59, with subsequent uncontrolled continuous spontaneous activation of the Complement Alternative Pathway (CAP) and, at times, of the Complement classical Pathway. Here we investigate in an in vitro model the effect on PNH erythrocytes of a novel therapeutic strategy for membrane-targeted delivery of a CAP inhibitor. TT30 is a 65 kDa recombinant human fusion protein consisting of the iC3b/C3d-binding region of Complement receptor 2 (CR2) and the inhibitory domain of the CAP regulator factor H (fH). TT30 completely inhibits in a dose-dependent manner hemolysis of PNH erythrocytes in a modified extended acidified serum assay, and also prevents C3 fragment deposition on surviving PNH erythrocytes. The efficacy of TT30 derives from its direct binding to PNH erythrocytes; if binding to the erythrocytes is disrupted, only partial inhibition of hemolysis is mediated by TT30 in solution, which is similar to that produced by the fH moiety of TT30 alone, or by intact human fH. TT30 is a membrane-targeted selective CAP inhibitor that may prevent both intravascular and C3-mediated extravascular hemolysis of PNH erythrocytes and warrants consideration for the treatment of PNH patients.
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design and development of tt30 a novel c3d targeted c3 c5 convertase inhibitor for treatment of human Complement Alternative Pathway mediated diseases
Blood, 2011Co-Authors: Masha Fridkishareli, Christopher J Horvath, Antonio M Risitano, Michael V Holers, Michael Storek, Ante S Lundberg, Istvan MazsaroffAbstract:To selectively modulate human Complement Alternative Pathway (CAP) activity implicated in a wide range of acute and chronic inflammatory conditions and to provide local cell surface and tissue-based inhibition of Complement-induced damage, we developed TT30, a novel therapeutic fusion protein linking the human Complement receptor type 2 (CR2/CD21) C3 fragment (C3frag = iC3b, C3dg, C3d)-binding domain with the CAP inhibitory domain of human factor H (fH). TT30 efficiently blocks ex vivo CAP-dependent C3frag accumulation on activated surfaces, membrane attack complex (MAC) formation and hemolysis of RBCs in a CR2-dependent manner, and with a ∼ 150-fold potency gain over fH, without interference of C3 activation or MAC formation through the classic and lectin Pathways. TT30 protects RBCs from hemolysis and remains bound and detectable for at least 24 hours. TT30 selectively inhibits CAP in cynomolgus monkeys and is bioavailable after subcutaneous injection. Using a unique combination of targeting and effector domains, TT30 controls cell surface CAP activation and has substantial potential utility for the treatment of human CAP-mediated diseases.
Lubka T Roumenina - One of the best experts on this subject based on the ideXlab platform.
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both monoclonal and polyclonal immunoglobulin contingents mediate Complement activation in monoclonal gammopathy associated c3 glomerulopathy
Frontiers in Immunology, 2018Co-Authors: Lubka T Roumenina, Marieagnes Dragondurey, Sophie Chauvet, Pierre Aucouturier, Mariachiara Marinozzi, Alexandre KarrasAbstract:C3 glomerulopathy (C3G) results from acquired or genetic abnormalities in the Complement Alternative Pathway (AP). C3G with monoclonal immunoglobulin (MIg-C3G) was recently included in the spectrum of "monoclonal gammopathy of renal significance." However, mechanisms of Complement dysregulation in MIg-C3G are not described and the pathogenic effect of the monoclonal immunoglobulin is not understood. The purpose of this study was to investigate the mechanisms of Complement dysregulation in a cohort of 41 patients with MIg-C3G. Low C3 level and elevated sC5b-9, both biomarkers of C3 and C5 convertase activation, were present in 44 and 78% of patients, respectively. Rare pathogenic variants were identified in 2/28 (7%) tested patients suggesting that the disease is acquired in a large majority of patients. Anti-Complement auto-antibodies were found in 20/41 (49%) patients, including anti-FH (17%), anti-CR1 (27%), anti-FI (5%) auto-antibodies, and C3 Nephritic Factor (7%) and were polyclonal in 77% of patients. Using cofactor assay, the regulation of the AP was altered in presence of purified IgG from 3/9 and 4/7 patients with anti-FH or anti-CR1 antibodies respectively. By using fluid and solid phase AP activation, we showed that total purified IgG of 22/34 (65%) MIg-C3G patients were able to enhance C3 convertase activity. In five documented cases, we showed that the C3 convertase enhancement was mostly due to the monoclonal immunoglobulin, thus paving the way for a new mechanism of Chauvet et al. C3 Glomerulopathy and Monoclonal Gammopathy Complement dysregulation in C3G. All together the results highlight the contribution of both polyclonal and monoclonal Ig in MIg-C3G. They provide direct insights to treatment approaches and opened up a potential way to a personalized therapeutic strategy based on chemotherapy adapted to the B cell clone or immunosuppressive therapy.
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Both Monoclonal and Polyclonal Immunoglobulin Contingents Mediate Complement Activation in Monoclonal Gammopathy Associated-C3 Glomerulopathy
Frontiers Media S.A., 2018Co-Authors: Lubka T Roumenina, Sophie Chauvet, Pierre Aucouturier, Mariachiara MarinozziAbstract:C3 glomerulopathy (C3G) results from acquired or genetic abnormalities in the Complement Alternative Pathway (AP). C3G with monoclonal immunoglobulin (MIg-C3G) was recently included in the spectrum of “monoclonal gammopathy of renal significance.” However, mechanisms of Complement dysregulation in MIg-C3G are not described and the pathogenic effect of the monoclonal immunoglobulin is not understood. The purpose of this study was to investigate the mechanisms of Complement dysregulation in a cohort of 41 patients with MIg-C3G. Low C3 level and elevated sC5b-9, both biomarkers of C3 and C5 convertase activation, were present in 44 and 78% of patients, respectively. Rare pathogenic variants were identified in 2/28 (7%) tested patients suggesting that the disease is acquired in a large majority of patients. Anti-Complement auto-antibodies were found in 20/41 (49%) patients, including anti-FH (17%), anti-CR1 (27%), anti-FI (5%) auto-antibodies, and C3 Nephritic Factor (7%) and were polyclonal in 77% of patients. Using cofactor assay, the regulation of the AP was altered in presence of purified IgG from 3/9 and 4/7 patients with anti-FH or anti-CR1 antibodies respectively. By using fluid and solid phase AP activation, we showed that total purified IgG of 22/34 (65%) MIg-C3G patients were able to enhance C3 convertase activity. In five documented cases, we showed that the C3 convertase enhancement was mostly due to the monoclonal immunoglobulin, thus paving the way for a new mechanism of Complement dysregulation in C3G. All together the results highlight the contribution of both polyclonal and monoclonal Ig in MIg-C3G. They provide direct insights to treatment approaches and opened up a potential way to a personalized therapeutic strategy based on chemotherapy adapted to the B cell clone or immunosuppressive therapy
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functional and structural insight into properdin control of Complement Alternative Pathway amplification
The EMBO Journal, 2017Co-Authors: Dennis Pedersen, Lubka T Roumenina, Rasmus K Jensen, Trine A F Gadeberg, Steffen Thiel, Chiara Marinozzi, Capucine Picard, Tania Rybkine, Uffe Bs Sorensen, Cordula M StoverAbstract:Properdin (FP) is an essential positive regulator of the Complement Alternative Pathway (AP) providing stabilization of the C3 and C5 convertases, but its oligomeric nature challenges structural analysis. We describe here a novel FP deficiency (E244K) caused by a single point mutation which results in a very low level of AP activity. Recombinant FP E244K is monomeric, fails to support bacteriolysis, and binds weakly to C3 products. We compare this to a monomeric unit excised from oligomeric FP, which is also dysfunctional in bacteriolysis but binds the AP proconvertase, C3 convertase, C3 products and partially stabilizes the convertase. The crystal structure of such a FP‐convertase complex suggests that the major contact between FP and the AP convertase is mediated by a single FP thrombospondin repeat and a small region in C3b. Small angle X‐ray scattering indicates that FP E244K is trapped in a compact conformation preventing its oligomerization. Our studies demonstrate an essential role of FP oligomerization in vivo while our monomers enable detailed structural insight paving the way for novel modulators of Complement. ![][1] Functional studies of oligomeric and two different monomeric forms of the Complement regulator FP demonstrate an essential role of oligomerization, while structural studies suggest that the contact between FP and the Alternative Pathway convertase is mainly mediated by a single FP thrombospondin repeat and a small region in C3b. [1]: /embed/graphic-1.gif
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loss of dgke induces endothelial cell activation and death independently of Complement activation
Blood, 2015Co-Authors: Sarah Bruneau, Lubka T Roumenina, Veronique Fremeauxbacchi, Melanie Neel, Marie Frimat, Laetitia Laurent, Fadi FakhouriAbstract:Atypical hemolytic uremic syndrome (aHUS) is classically described to result from a dysregulation of the Complement Alternative Pathway, leading to glomerular endothelial cell (EC) damage and thrombosis. However, recent findings in families with aHUS of mutations in the DGKE gene, which is not an
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Acquired and genetic Complement abnormalities play a critical role in dense deposit disease and other C3 glomerulopathies
Kidney international, 2012Co-Authors: Aude Servais, Lubka T Roumenina, Laurehelene Noel, Marie-agnès Dragon-durey, Moglie Le Quintrec, Stéphanie Ngo, Marie-alice Macher, Julien Zuber, Alexandre Karras, François ProvôtAbstract:Dense deposit disease and glomerulonephritis with isolated C3 deposits are glomerulopathies characterized by deposits of C3 within or along the glomerular basement membrane. Previous studies found a link between dysregulation of the Complement Alternative Pathway and the pathogenesis of these diseases. We analyzed the role of acquired and genetic Complement abnormalities in a cohort of 134 patients, of whom 29 have dense deposit disease, 56 have glomerulonephritis with isolated C3 deposits, and 49 have primary membranoproliferative glomerulonephritis type I, with adult and pediatric onset. A total of 53 patients presented with a low C3 level, and 65 were positive for C3 nephritic factor that was significantly more frequently detected in patients with dense deposit disease than in other histological types. Mutations in CFH and CFI genes were identified in 24 patients associated with a C3 nephritic factor in half the cases. We found evidence for Complement Alternative Pathway dysregulation in 26 patients with membranoproliferative glomerulonephritis type I. The Complement factor H Y402H variant was significantly increased in dense deposit disease. We identified one at-risk membrane cofactor protein (MCP) haplotype for glomerulonephritis with isolated C3 deposits and membranoproliferative glomerulonephritis type I. Thus, our results suggest a critical role of fluid-phase Alternative Pathway dysregulation in the pathogenesis of C3 glomerulopathies as well as in immune complex–mediated glomerular diseases. The localization of the C3 deposits may be under the influence of MCP expression.