title: A chemically-modified inactive antithrombin as a potent antagonist of fondaparinux and heparin anticoagulant activity.
abstract: BACKGROUND
  Heparin and its analogs, mediating their anticoagulant activity through antithrombin (AT) activation, remain largely used for the preventive and curative treatment of thrombosis. The major adverse reaction of these drugs is the bleeding risk associated with overdose. Unfractionnated heparin (UFH) can be efficiently and rapidly neutralized by protamine sulfate, but this reversal partially neutralizes low-molecular-weight heparin (LMWH) and is inefficient in reversing fondaparinux. To secure administration of AT-mediated anticoagulants and counteract bleeding disorders, we previously designed a recombinant inactive AT as an antidote to heparin derivatives.
  
  
  OBJECTIVE
  To get around the limited production level of recombinant AT, we propose in this study an alternative strategy to produce a chemically modified inactive AT, exhibiting increased heparin affinity, as an antagonist of heparin analogs.
  
  
  METHODS
  Plasma-derived AT was chemically modified with 2,3 butanedione, a diketone known to specifically react with the arginine side chain. The chemical reaction was conducted in the presence of heparin to preserve basic residues within the heparin binding site from modifications.
  
  
  RESULTS
  AT treated by butanedione and selected for its high heparin affinity (AT-BD) was indeed modified on reactive Arg393 and thus exhibited decreased anticoagulant activity and increased heparin affinity. AT-BD was able to neutralize anticoagulant activity of heparin derivatives in vitro and in vivo and was devoid of intrinsic anticoagulant activity, as assessed by activated partial thromboplastin time assay.
  
  
  CONCLUSIONS
  AT-BD appears to be as efficient as protamine to neutralize UFH in vivo but could be more largely used because it also reverses fondaparinux and LMWH.
authors.affiliation: Laboratoire d'Hématologie, University Paris-Sud-XI, Châtenay-Malabry Cedex, France.
authors.forename: J
authors.initials: J
authors.lastname: Fazavana
authors.forename: E P
authors.initials: EP
authors.lastname: Bianchini
authors.forename: F
authors.initials: F
authors.lastname: Saller
authors.forename: C
authors.initials: C
authors.lastname: Smadja
authors.forename: V
authors.initials: V
authors.lastname: Picard
authors.forename: M
authors.initials: M
authors.lastname: Taverna
authors.forename: D
authors.initials: D
authors.lastname: Borgel
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000737:chemistry*; D000991:Antithrombins / Q000737:chemistry / Q000627:therapeutic use*; D001120:Arginine / Q000737:chemistry; D003931:Diacetyl / Q000737:chemistry; D015195:Drug Design; D005260:Female; D000077425:Fondaparinux; D006470:Hemorrhage; D006493:Heparin / Q000737:chemistry; D006494:Heparin Antagonists / Q000737:chemistry*; D006801:Humans; D013058:Mass Spectrometry; D051379:Mice; D010314:Partial Thromboplastin Time; D011134:Polysaccharides / Q000037:antagonists & inhibitors* / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry; D012306:Risk
chemical_list: D000925:Anticoagulants; D000991:Antithrombins; D006494:Heparin Antagonists; D011134:Polysaccharides; D011994:Recombinant Proteins; D006493:Heparin; D001120:Arginine; D000077425:Fondaparinux; D003931:Diacetyl
keywords: antidotes; antithrombins; butanedione; fondaparinux; heparin; heparin antagonists