Redox Biology (Apr 2017)

DioxolaneA3-phosphatidylethanolamines are generated by human platelets and stimulate neutrophil integrin expression

  • Maceler Aldrovandi,
  • Christine Hinz,
  • Sarah N. Lauder,
  • Helen Podmore,
  • Martin Hornshaw,
  • David A. Slatter,
  • Victoria J. Tyrrell,
  • Stephen R. Clark,
  • Lawrence J. Marnett,
  • Peter W. Collins,
  • Robert C. Murphy,
  • Valerie B. O’Donnell

Journal volume & issue
Vol. 11
pp. 663 – 672

Abstract

Read online

Activated platelets generate an eicosanoid proposed to be 8-hydroxy-9,10-dioxolane A3 (DXA3). Herein, we demonstrate that significant amounts of DXA3 are rapidly attached to phosphatidylethanolamine (PE) forming four esterified eicosanoids, 16:0p, 18:0p, 18:1p and 18:0a/DXA3-PEs that can activate neutrophil integrin expression. These lipids comprise the majority of DXA3 generated by platelets, are formed in ng amounts (24.3±6.1 ng/2×108) and remain membrane bound. Pharmacological studies revealed DXA3-PE formation involves cyclooxygenase-1 (COX), protease-activated receptors (PAR) 1 and 4, cytosolic phospholipase A2 (cPLA2), phospholipase C and intracellular calcium. They are generated primarily via esterification of newly formed DXA3, but can also be formed in vitro via co-oxidation of PE during COX-1 co-oxidation of arachidonate. All four DXA3-PEs were detected in human clots. Purified platelet DXA3-PE activated neutrophil Mac-1 expression, independently of its hydrolysis to the free eicosanoid. This study demonstrates the structures and cellular synthetic pathway for a family of leukocyte-activating platelet phospholipids generated on acute activation, adding to the growing evidence that enzymatic PE oxidation is a physiological event in innate immune cells. Keywords: Eicosanoids, Platelets, Cyclooxygenase, Phospholipids, Mass spectrometry