title: Staphylococcal extracellular adherence protein induces platelet activation by stimulation of thiol isomerases.
abstract: OBJECTIVE
  Staphylococcus aureus can induce platelet aggregation. The rapidity and degree of this correlates with the severity of disseminated intravascular coagulation, and depends on platelet peptidoglycans. Surface-located thiol isomerases play an important role in platelet activation. The staphylococcal extracellular adherence protein (Eap) functions as an adhesin for host plasma proteins. Therefore we tested the effect of Eap on platelets.
  
  
  RESULTS
  We found a strong stimulation of the platelet-surface thiol isomerases protein disulfide isomerase and endoplasmic reticulum stress proteins 57 and 72 by Eap. Eap induced thiol isomerase-dependent glycoprotein IIb/IIIa activation, granule secretion, and platelet aggregation. Treatment of platelets with thiol blockers, bacitracin, and anti-protein disulfide isomerase antibody inhibited Eap-induced platelet activation. The effect of Eap on platelets and protein disulfide isomerase activity was completely blocked by glycosaminoglycans. Inhibition by the hydrophobic probe bis(1-anilinonaphthalene 8-sulfonate) suggested the involvement of hydrophobic sites in protein disulfide isomerase and platelet activation by Eap.
  
  
  CONCLUSIONS
  In the present study, we found an additional and yet unknown mechanism of platelet activation by a bacterial adhesin, involving stimulation of thiol isomerases. The thiol isomerase stimulatory and prothrombotic features of a microbial secreted protein are probably not restricted to S aureus and Eap. Because many microorganisms are coated with amyloidogenic proteins, it is likely that the observed mechanism is a more general one.
authors.affiliation: Department of Anesthesiology and Intensive Care, Experimental and Clinical Hemostasis, University of Muenster, Mendelstr 11, 48149 Muenster, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Bertling
authors.forename: Silke
authors.initials: S
authors.lastname: Niemann
authors.forename: Muzaffar
authors.initials: M
authors.lastname: Hussain
authors.forename: Lisa
authors.initials: L
authors.lastname: Holbrook
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Stanley
authors.forename: Martin F
authors.initials: MF
authors.lastname: Brodde
authors.forename: Silke
authors.initials: S
authors.lastname: Pohl
authors.forename: Tina
authors.initials: T
authors.lastname: Schifferdecker
authors.forename: Joachim
authors.initials: J
authors.lastname: Roth
authors.forename: Kerstin
authors.initials: K
authors.lastname: Jurk
authors.forename: Anja
authors.initials: A
authors.lastname: Müller
authors.forename: Judith
authors.initials: J
authors.lastname: Lahav
authors.forename: Georg
authors.initials: G
authors.lastname: Peters
authors.forename: Christine
authors.initials: C
authors.lastname: Heilmann
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Gibbins
authors.forename: Beate E
authors.initials: BE
authors.lastname: Kehrel
mesh_terms: D000817:Anilino Naphthalenesulfonates / Q000494:pharmacology; D001426:Bacterial Proteins / Q000494:pharmacology*; D001792:Blood Platelets / Q000201:enzymology; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D006801:Humans; D019007:P-Selectin / Q000097:blood; D015539:Platelet Activation / Q000187:drug effects*; D019704:Protein Disulfide-Isomerases / Q000502:physiology*; D011509:Proteoglycans / Q000494:pharmacology; D016601:RNA-Binding Proteins / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000472:pathogenicity*; D060149:Tetraspanin 30 / Q000097:blood
chemical_list: D000817:Anilino Naphthalenesulfonates; D001426:Bacterial Proteins; C554586:CD63 protein, human; C444739:Eap-N protein, Staphylococcus aureus; D019007:P-Selectin; D011509:Proteoglycans; D016601:RNA-Binding Proteins; D060149:Tetraspanin 30; C035763:5,5'-bis(8-(phenylamino)-1-naphthalenesulfonate); D004228:Dithionitrobenzoic Acid; D019704:Protein Disulfide-Isomerases