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

Redox Biol. 2017 Apr:11:663-672. doi: 10.1016/j.redox.2017.01.001. Epub 2017 Jan 13.

Abstract

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±6.1ng/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: Cyclooxygenase; Eicosanoids; Mass spectrometry; Phospholipids; Platelets.

MeSH terms

  • Blood Platelets / metabolism*
  • Calcium / blood
  • Cyclooxygenase 1 / blood
  • Dioxolanes / blood*
  • Eicosanoids / blood
  • Gene Expression Regulation
  • Humans
  • Integrins / biosynthesis
  • Integrins / blood*
  • Lipids / blood*
  • Macrophage-1 Antigen / genetics
  • Neutrophils / metabolism
  • Oxidation-Reduction
  • Phosphatidylethanolamines / blood*
  • Phospholipases A2, Cytosolic / blood
  • Platelet Activation / genetics
  • Receptor, PAR-1 / blood
  • Receptors, Thrombin / blood
  • Thrombin / metabolism
  • Type C Phospholipases / blood

Substances

  • Dioxolanes
  • Eicosanoids
  • Integrins
  • Lipids
  • Macrophage-1 Antigen
  • Phosphatidylethanolamines
  • Receptor, PAR-1
  • Receptors, Thrombin
  • phosphatidylethanolamine
  • Cyclooxygenase 1
  • Phospholipases A2, Cytosolic
  • Type C Phospholipases
  • Thrombin
  • protease-activated receptor 4
  • Calcium
  • formal glycol