title: Differential Inhibition of Human Atherosclerotic Plaque-Induced Platelet Activation by Dimeric GPVI-Fc and Anti-GPVI Antibodies: Functional and Imaging Studies.
abstract: BACKGROUND
  Glycoprotein VI (GPVI) is the essential platelet collagen receptor in atherothrombosis, but its inhibition causes only a mild bleeding tendency. Thus, targeting this receptor has selective antithrombotic potential.
  
  
  OBJECTIVE
  This study sought to compare compounds interfering with platelet GPVI-atherosclerotic plaque interaction to improve current antiatherothrombotic therapy.
  
  
  METHODS
  Human atherosclerotic plaque-induced platelet aggregation was measured in anticoagulated blood under static and arterial flow conditions (550/s, 1,100/s, and 1,500/s). Inhibition by dimeric GPVI fragment crystallizable region of IgG (Fc) masking GPVI binding sites on collagen was compared with that of 3 anti-GPVI antibodies: BLO8-1, a human domain antibody; 5C4, a fragment antigen-binding (Fab fragment) of monoclonal rat immunoglobulin G; and m-Fab-F, a human recombinant sFab against GPVI dimers.
  
  
  RESULTS
  GPVI-Fc reduced plaque-triggered platelet aggregation in static blood by 51%, BLO8-1 by 88%, and 5C4 by 93%. Under arterial flow conditions, BLO8-1 and 5C4 almost completely inhibited platelet aggregation while preserving platelet adhesion on plaque. Inhibition by GPVI-Fc, even at high concentrations, was less marked but increased with shear rate. Advanced optical imaging revealed rapid persistent GPVI-Fc binding to collagen under low and high shear flow, upstream and downstream of plaque fragments. At low shear particularly, platelets adhered in plaque flow niches to GPVI-Fc-free segments of collagen fibers and recruited other platelets onto aggregates via ADP and TxA2 release.
  
  
  CONCLUSIONS
  Anti-GPVI antibodies inhibit atherosclerotic plaque-induced platelet aggregation under static and flow conditions more effectively than GPVI-Fc. However, potent platelet inhibition by GPVI-Fc at a higher shear rate (1,500/s) suggests localized antithrombotic efficacy at denuded or fissured stenotic high-risk lesions without systemic bleeding. The compound-specific differences have relevance for clinical trials targeting GPVI-collagen interaction combined with established antiplatelet therapies in patients with spontaneous plaque rupture or intervention-associated plaque injury.
authors.affiliation: Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany.
authors.forename: Janina
authors.initials: J
authors.lastname: Jamasbi
authors.affiliation: Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany; Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands.
authors.forename: Remco T A
authors.initials: RT
authors.lastname: Megens
authors.affiliation: Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany.
authors.forename: Mariaelvy
authors.initials: M
authors.lastname: Bianchini
authors.affiliation: advanceCOR GmbH, Munich, Germany.
authors.forename: Götz
authors.initials: G
authors.lastname: Münch
authors.affiliation: advanceCOR GmbH, Munich, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Ungerer
authors.affiliation: Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Faussner
authors.affiliation: Department of Life Sciences, Ben Gurion University, Beer-Sheva, Israel.
authors.forename: Shachar
authors.initials: S
authors.lastname: Sherman
authors.affiliation: GlaxoSmithKline Research & Development, Brentford, Middlesex, United Kingdom.
authors.forename: Adam
authors.initials: A
authors.lastname: Walker
authors.affiliation: Department of Biotechnology, The Central University of Rajasthan, Rajasthan, India.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Goyal
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Jung
authors.affiliation: St. Mary's Square Institute for Vascular Surgery and Phlebology, Munich, Germany.
authors.forename: Richard
authors.initials: R
authors.lastname: Brandl
authors.affiliation: Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany; Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands; DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, Munich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Weber
authors.affiliation: Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Lorenz
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Richard
authors.initials: R
authors.lastname: Farndale
authors.affiliation: Department of Life Sciences, Ben Gurion University, Beer-Sheva, Israel.
authors.forename: Natalie
authors.initials: N
authors.lastname: Elia
authors.affiliation: Institute for the Prevention of Cardiovascular Diseases, University of Munich, Munich, Germany; DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, Munich, Germany. Electronic address: wsiess@med.uni-muenchen.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Siess
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology*; D002339:Carotid Arteries / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D016893:Carotid Stenosis / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000494:pharmacology*; D007155:Immunologic Factors / Q000494:pharmacology; D058226:Plaque, Atherosclerotic / Q000150:complications / Q000175:diagnosis / Q000188:drug therapy*; D015539:Platelet Activation / Q000187:drug effects*; D010980:Platelet Membrane Glycoproteins / Q000494:pharmacology*; D051381:Rats
chemical_list: D007140:Immunoglobulin Fab Fragments; D007155:Immunologic Factors; D010980:Platelet Membrane Glycoproteins; C098341:platelet membrane glycoprotein VI
keywords: antithrombotic; atherothrombosis; glycoprotein VI; plaque rupture