title: The inflammatory chemokine CXC motif ligand 16 triggers platelet activation and adhesion via CXC motif receptor 6-dependent phosphatidylinositide 3-kinase/Akt signaling.
abstract: BACKGROUND
  The recently discovered chemokine CXC motif ligand 16 (CXCL16) is highly expressed in atherosclerotic lesions and is a potential pathogenic mediator in coronary artery disease.
  
  
  OBJECTIVE
  The aim of this study was to test the role of CXCL16 on platelet activation and vascular adhesion, as well as the underlying mechanism and signaling pathway.
  
  
  RESULTS
  Reverse-transcriptase polymerase chain reaction, Western blotting, confocal microscopy, and flow cytometry revealed that CXCL16-specific receptor, CXC motif receptor 6, is highly expressed in platelets. According to flow cytometry and confocal microscopy, stimulation of platelets with CXCL16 induced platelet degranulation, integrin α(IIb)β(3) activation, and shape change. CXCL16 increased Akt phosphorylation (Thr(308)/Ser(473)), an effect abrogated by phosphatidylinositide 3-kinase inhibitors wortmannin (100 nmol/L) and LY294002 (25 µmol/L). The phosphatidylinositide 3-kinase inhibitors and Akt inhibitor SH-6 (20 µmol/L) further diminished CXCL16-induced platelet activation. CXCL16-mediated platelet degranulation, integrin α(IIb)β(3) activation, and Akt phosphorylation were blunted in platelets lacking CXCL16-specific receptor CXC motif receptor 6. CXCL16-induced platelet activation was abrogated in Akt1- or Akt2-deficient platelets. CXCL16 enhanced platelet adhesion to endothelium in vitro after high arterial shear stress (2000(-s)) and to injured vascular wall in vivo after carotid ligation. CXCL16-induced stimulation of platelet adhesion again was prevented by phosphatidylinositide 3-kinase and Akt inhibitors. Apyrase and antagonists of platelet purinergic receptors P(2)Y(1) (MRS2179, 100 µmol/L) and especially P(2)Y(12) (Cangrelor, 10 µmol/L) blunted CXCL16-triggered platelet activation as well as CXCL16-induced platelet adhesion under high arterial shear stress in vitro and after carotid ligation in vivo.
  
  
  CONCLUSIONS
  The inflammatory chemokine CXCL16 triggers platelet activation and adhesion via CXC motif receptor 6-dependent phosphatidylinositide 3-kinase/Akt signaling and paracrine activation, suggesting a decisive role for CXCL16 in linking vascular inflammation and thrombo-occlusive diseases.
authors.affiliation: Medizinische Klinik III, Department of Cardiology and Cardiovascular Medicine, University of Tübingen, Otfried-Müller-St 10, 72076 Tübingen, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Borst
authors.forename: Patrick
authors.initials: P
authors.lastname: Münzer
authors.forename: Sergios
authors.initials: S
authors.lastname: Gatidis
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Schmidt
authors.forename: Tanja
authors.initials: T
authors.lastname: Schönberger
authors.forename: Evi
authors.initials: E
authors.lastname: Schmid
authors.forename: Syeda T
authors.initials: ST
authors.lastname: Towhid
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Stellos
authors.forename: Peter
authors.initials: P
authors.lastname: Seizer
authors.forename: Andreas E
authors.initials: AE
authors.lastname: May
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
authors.forename: Meinrad
authors.initials: M
authors.lastname: Gawaz
mesh_terms: D000818:Animals; D001572:Benzofurans; D001792:Blood Platelets / Q000276:immunology / Q000378:metabolism; D000075743:Chemokine CXCL16; D054427:Chemokine CXCL6 / Q000276:immunology* / Q000378:metabolism*; D003324:Coronary Artery Disease / Q000276:immunology / Q000378:metabolism; D004730:Endothelium, Vascular / Q000276:immunology / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D015539:Platelet Activation / Q000276:immunology*; D010973:Platelet Adhesiveness / Q000276:immunology*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D011804:Quinolines; D054387:Receptors, CXCR / Q000235:genetics / Q000378:metabolism; D000075744:Receptors, CXCR6; D015398:Signal Transduction / Q000276:immunology*; D013927:Thrombosis / Q000276:immunology / Q000378:metabolism; D014657:Vasculitis / Q000276:immunology / Q000378:metabolism
chemical_list: C576715:(3aS,4S,9bS)-N-(2-(8-cyano-1-formyl-2,3,3a,4,5,9b-hexahydro-1H-pyrrolo(3,2-c)quinolin-4-yl)-2-methylpropyl)-4,6-difluorobenzofuran-2-carboxyamide; D001572:Benzofurans; D000075743:Chemokine CXCL16; D054427:Chemokine CXCL6; C498926:Cxcl16 protein, mouse; C482906:Cxcr6 protein, mouse; D011804:Quinolines; D054387:Receptors, CXCR; D000075744:Receptors, CXCR6; D019869:Phosphatidylinositol 3-Kinases; C514862:Akt1 protein, mouse; C494922:Akt2 protein, mouse; D051057:Proto-Oncogene Proteins c-akt