Systems Immunity Research Institute, and Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK
Victoria J. Tyrrell
Systems Immunity Research Institute, and Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK
Stephen R. Clark
Systems Immunity Research Institute, and Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK
Lawrence J. Marnett
Vanderbilt Institute of Chemical Biology, Centre in Molecular Toxicology, Vanderbilt-Ingram Cancer Centre, Nashville, TN, USA
Peter W. Collins
Systems Immunity Research Institute, and Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK
Robert C. Murphy
Department of Pharmacology, University of Colorado Denver, Aurora, CO 80045, USA
Valerie B. O’Donnell
Systems Immunity Research Institute, and Institute of Infection and Immunity, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK; Corresponding author.
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
