title: Low concentrations of reactive gamma-ketoaldehydes prime thromboxane-dependent human platelet aggregation via p38-MAPK activation.
abstract: Oxidative stress has been strongly implicated in pathological processes. Isoketals are highly reactive gamma-ketoaldehydes of the isoprostanes pathway of free radical-induced peroxidation of arachidonic acid that are analogous to cyclooxygenase-derived levuglandins. Because aldehydes, that are much less reactive than isoketals, have been shown to trigger platelet activation, we investigated the effect of one isoketal (E(2)-IsoK) on platelet aggregation. Isoketal potentiated aggregation and the formation of thromboxane B(2) in platelets challenged with collagen at a concentration as low as 1 nM. Moreover, the potentiating effect of 1 nM isoketal on collagen-induced platelet aggregation was prevented by pyridoxamine, an effective scavenger of gamma-ketoaldehydes. Furthermore, we provide evidence for the involvement of p38 mitogen-activated protein kinase in isoketal-mediated platelet priming, suggesting that isoketals may act upstream the activation of collagen-induced cytosolic phospholipase A(2). Additionally, the incubation of platelets with 1 nM isoketal led to the phosphorylation of cytosolic phospholipase A(2). The cytosolic phopholipase A(2) inhibitors AACOCF3 and MAFP both fully prevented the increase in isoketal-mediated platelet aggregation challenged with collagen. These results indicate that isoketals could play an important role in platelet hyperfunction observed in pathological states such as atherosclerosis and thrombosis through the activation of the endogenous arachidonic acid cascade.
authors.affiliation: Université de Lyon, F-69622, Lyon, France; Univ Lyon 1, Villeurbanne, Insa-Lyon F-69621 Villeurbanne, France. nathalie.bernoud-hubac@insa-lyon.fr
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bernoud-Hubac
authors.forename: Denise Al
authors.initials: DA
authors.lastname: Alam
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lefils
authors.forename: Sean S
authors.initials: SS
authors.lastname: Davies
authors.forename: Venkataraman
authors.initials: V
authors.lastname: Amarnath
authors.forename: Michel
authors.initials: M
authors.lastname: Guichardant
authors.forename: L Jackson
authors.initials: LJ
authors.lastname: Roberts
authors.forename: Michel
authors.initials: M
authors.lastname: Lagarde
mesh_terms: D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D015153:Blotting, Western; D003094:Collagen / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology; D006801:Humans; D028421:Isoprostanes / Q000494:pharmacology*; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D054467:Phospholipases A2 / Q000378:metabolism; D010766:Phosphorylation; D015539:Platelet Activation / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects*; D011458:Prostaglandins E / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D011733:Pyridoxamine / Q000494:pharmacology; D013929:Thromboxane B2 / Q000378:metabolism*; D014803:Vitamin B Complex / Q000494:pharmacology
chemical_list: D028421:Isoprostanes; D011458:Prostaglandins E; D011518:Proto-Oncogene Proteins; D014803:Vitamin B Complex; D013929:Thromboxane B2; D011733:Pyridoxamine; D003094:Collagen; C047684:levuglandin E2; D020930:MAP Kinase Kinase Kinases; C069937:MAP3K8 protein, human; D054467:Phospholipases A2