Mediators and molecular pathways involved in the regulation of neutrophil extracellular trap (NET) formation mediated by activated platelets.

CARESTIA, A; KAUFMAN, T; RIVADENEYRA, L; LANDONI, VI; POZNER, RG; NEGROTTO, S; D'ATRI, LP; GOMEZ, RM; SCHATTNER, M

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Congreso; Cell Biology of Megakaryocytes & Platelets Gordon Research Conference; 2015

Mediators and molecular pathways involved in the regulation of neutrophil extracellular trap (NET) formation mediated by activated plateletsAgostina Carestia, Tomás Kaufman, Leonardo Rivadeneyra, Verónica Inés Landoni, Roberto Gabriel Pozner, Soledad Negrotto, Lina Paola D?Atri, Ricardo Martín Gómez, and Mirta SchattnerIn addition to being key elements in hemostasis and thrombosis, platelets amplify neutrophil function. We aimed to gain further insight into the stimuli, mediators, molecular pathways and regulation of neutrophil extracellular trap (NET) formation mediated by human platelets. Platelets stimulated by lipopolysaccharide (LPS), a wall component of Gram-negative bacteria, Pam3CSK4, a mimetic of lipopeptide from Gram-positive bacteria, or physiological platelet agonists promoted NET formation and myeloperoxidase-associated DNA activity under static and flow conditions. While P-selectin or glycoprotein (GP)IIbIIIa were not involved, platelet GPIb and neutrophil CD18 and the release of von Willebrand factor (vWF) and platelet factor 4 (PF4) seemed to be critical for NETosis. The secretion of these molecules depended on thromboxane A2 production triggered by LPS or Pam3CSK4 but not by high concentrations of thrombin. Accordingly, aspirin selectively inhibited platelet-mediated NETosis. Signaling through ERK, PI3K, and Src kinases but not p38 or NADPH oxidase was involved in platelet-triggered NET release. Platelet-mediated NET formation was inhibited by prostacyclin and nitric oxide as well as by acidosis. Our results support a role of stimulated-platelets in promoting NETosis, reveal that endothelium-derived molecules and stress conditions of the inflammatory milieu contribute to limit NET formation and highlight platelet inhibition as a potential target for controlling NETosis.