title: ADAMTS13 autoantibodies cloned from patients with acquired thrombotic thrombocytopenic purpura: 2. Pathogenicity in an animal model.
abstract: Acquired thrombotic thrombocytopenic purpura (TTP) is a potentially fatal disease in which ultralarge von Willebrand factor (UL-VWF) multimers accumulate as a result of autoantibody inhibition of the VWF protease, ADAMTS13. Current treatment is not specifically directed at the responsible autoantibodies and in some cases is ineffective or of transient benefit. More rational, reliable, and durable therapies are needed, and a human autoantibody-mediated animal model would be useful for their development. Previously, TTP patient anti-ADAMTS13 single-chain variable-region fragments (scFv's) were cloned that inhibited ADAMTS13 proteolytic activity in vitro and expressed features in common with inhibitory immunoglobulin G in patient plasma. Here, pathogenicity of these scFv's is explored in vivo by transfecting mice with inhibitory antibody cDNA.
  
  
  
  Hydrodynamic tail vein injection of naked DNA encoding human anti-ADAMTS13 scFv was used to create sustained ADAMTS13 inhibition in mice. Accumulation of UL-VWF multimers was measured and formation of platelet (PLT) thrombi after focal or systemic vascular injury was examined.
  
  
  
  Transfected mice expressed physiological plasma levels of human scFv and developed sustained ADAMTS13 inhibition and accumulation of unprocessed UL-VWF multimers. Induced focal endothelial injury generated PLT thrombi extending well beyond the site of initial injury, and systemic endothelial injury induced thrombocytopenia, schistocyte formation, PLT thrombi, and death.
  
  
  
  These results demonstrate for the first time the ability of human recombinant monovalent anti-ADAMTS13 antibody fragments to recapitulate key pathologic features of untreated acquired TTP in vivo, validating their clinical significance and providing an animal model for testing novel targeted therapeutic approaches.
authors.affiliation: Department of Pathology & Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.|Poseida Therapeutics, Inc, San Diego, California.
authors.forename: Eric M
authors.initials: EM
authors.lastname: Ostertag
authors.affiliation: Department of Pathology & Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Khalil
authors.initials: K
authors.lastname: Bdeir
authors.affiliation: Department of Pathology & Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Stephen
authors.initials: S
authors.lastname: Kacir
authors.affiliation: Department of Pathology & Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Michelle
authors.initials: M
authors.lastname: Thiboutot
authors.affiliation: Department of Pathology & Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Gayathri
authors.initials: G
authors.lastname: Gulendran
authors.affiliation: Department of Pathology & Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Lenka
authors.initials: L
authors.lastname: Yunk
authors.affiliation: Division of Hematology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Hayes
authors.affiliation: Bloodworks Northwest Research Institute, Seattle, Washington.
authors.forename: David G
authors.initials: DG
authors.lastname: Motto
authors.affiliation: Division of Hematology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Mortimer
authors.initials: M
authors.lastname: Poncz
authors.affiliation: Department of Pathology & Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.|Division of Laboratory Medicine, Department of Pathology, The University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: X Long
authors.initials: XL
authors.lastname: Zheng
authors.affiliation: Department of Pathology & Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Cines
authors.affiliation: Department of Pathology & Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Don L
authors.initials: DL
authors.lastname: Siegel
mesh_terms: D000071120:ADAMTS13 Protein / Q000037:antagonists & inhibitors* / Q000276:immunology; D000818:Animals; D001323:Autoantibodies / Q000235:genetics; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000008:administration & dosage; D006801:Humans; D051379:Mice; D023421:Models, Animal; D058990:Molecular Targeted Therapy / Q000379:methods; D011697:Purpura, Thrombotic Thrombocytopenic / Q000276:immunology* / Q000628:therapy*; D057127:Single-Chain Antibodies / Q000235:genetics / Q000633:toxicity; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D001323:Autoantibodies; D018076:DNA, Complementary; D057127:Single-Chain Antibodies; D014841:von Willebrand Factor; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human