title: Selectivity of C3-opsonin targeted complement inhibitors: A distinct advantage in the protection of erythrocytes from paroxysmal nocturnal hemoglobinuria patients.
abstract: Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by complement-mediated cell lysis due to deficiency of GPI-anchored complement regulators. Blockage of the lytic pathway by eculizumab is the only available therapy for PNH patients and shows remarkable benefits, but regularly yields PNH erythrocytes opsonized with fragments of complement protein C3, rendering such erythrocytes prone to extravascular hemolysis. This effect is associated with insufficient responsiveness seen in a subgroup of PNH patients. Novel C3-opsonin targeted complement inhibitors act earlier in the cascade, at the level of activated C3 and are engineered from parts of the natural complement regulator Factor H (FH) or complement receptor 2 (CR2). This inhibitor class comprises three variants of "miniFH" and the clinically developed "FH-CR2" fusion-protein (TT30). We show that the approach of FH-CR2 to target C3-opsonins was more efficient in preventing complement activation induced by foreign surfaces, whereas the miniFH variants were substantially more active in controlling complement on PNH erythrocytes. Subtle differences were noted in the ability of each version of miniFH to protect human PNH cells. Importantly, miniFH and FH-CR2 interfered only minimally with complement-mediated serum killing of bacteria when compared to untargeted inhibition of all complement pathways by eculizumab. Thus, the molecular design of each C3-opsonin targeted complement inhibitor determines its potency in respect to the nature of the activator/surface providing potential functionality in PNH.
authors.affiliation: Institute of Pharmacology of Natural Products and Clinical Pharmacology, Ulm University, Ulm, Germany. Electronic address: christoph.schmidt@uni-ulm.de.
authors.forename: Christoph Q
authors.initials: CQ
authors.lastname: Schmidt
authors.affiliation: Institute of Pharmacology of Natural Products and Clinical Pharmacology, Ulm University, Ulm, Germany.
authors.forename: Markus J
authors.initials: MJ
authors.lastname: Harder
authors.affiliation: Institutes of Cellular Medicine and Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Nichols
authors.affiliation: Junior Research Group Cellular Immunobiology, Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany.
authors.forename: Mario
authors.initials: M
authors.lastname: Hebecker
authors.affiliation: Institute of Clinical Transfusion Medicine and Immunogenetics Ulm, University of Ulm and German Red Cross Blood Service Baden-Württemberg - Hessen, Ulm, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Anliker
authors.affiliation: Institute of Clinical Transfusion Medicine and Immunogenetics Ulm, University of Ulm and German Red Cross Blood Service Baden-Württemberg - Hessen, Ulm, Germany.
authors.forename: Britta
authors.initials: B
authors.lastname: Höchsmann
authors.affiliation: Institute of Pharmacology of Natural Products and Clinical Pharmacology, Ulm University, Ulm, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Simmet
authors.affiliation: MTA-ELTE "Lendület" Complement Research Group, Department of Immunology, Eötvös Loránd University, Budapest, Hungary.
authors.forename: Ádám I
authors.initials: ÁI
authors.lastname: Csincsi
authors.affiliation: MTA-ELTE Immunology Research Group, Department of Immunology, Eötvös Loránd University, Budapest, Hungary.
authors.forename: Barbara
authors.initials: B
authors.lastname: Uzonyi
authors.affiliation: Institutes of Cellular Medicine and Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Isabel Y
authors.initials: IY
authors.lastname: Pappworth
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Ricklin
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Lambris
authors.affiliation: Institute of Clinical Transfusion Medicine and Immunogenetics Ulm, University of Ulm and German Red Cross Blood Service Baden-Württemberg - Hessen, Ulm, Germany.
authors.forename: Hubert
authors.initials: H
authors.lastname: Schrezenmeier
authors.affiliation: MTA-ELTE "Lendület" Complement Research Group, Department of Immunology, Eötvös Loránd University, Budapest, Hungary.
authors.forename: Mihály
authors.initials: M
authors.lastname: Józsi
authors.affiliation: Institutes of Cellular Medicine and Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Marchbank
mesh_terms: D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000096:biosynthesis / Q000276:immunology / Q000494:pharmacology*; D002478:Cells, Cultured; D003167:Complement Activation / Q000187:drug effects; D003176:Complement C3 / Q000235:genetics*; D017242:Complement Factor H / Q000235:genetics / Q000276:immunology; D051056:Complement Inactivating Agents / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D003170:Complement Pathway, Alternative; D004912:Erythrocytes / Q000187:drug effects* / Q000276:immunology / Q000473:pathology; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D015870:Gene Expression; D006457:Hemoglobinuria, Paroxysmal / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D058990:Molecular Targeted Therapy; D009895:Opsonin Proteins / Q000235:genetics*; D015202:Protein Engineering; D011817:Rabbits; D017464:Receptors, Complement 3d / Q000235:genetics / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D003176:Complement C3; D051056:Complement Inactivating Agents; D009895:Opsonin Proteins; D017464:Receptors, Complement 3d; D011993:Recombinant Fusion Proteins; C574810:TT30 fusion protein, human; D017242:Complement Factor H; C481642:eculizumab
keywords: Alternative pathway; Complement targeted inhibition; Paroxysmal nocturnal hemoglobinuria; miniFH