Activated platelets and monocytes generate four hydroxyphosphatidylethanolamines via lipoxygenase.
12/15-Lipoxygenase (LOX) mediates immune-regulatory activities not accounted for by its known free acid eicosanoids, suggesting that additional lipids may be generated by activated cells. To characterize novel LOX-derived lipids, a lipidomic approach was utilized. Ionophore-activated interleukin-4-treated human peripheral monocytes generated up to 10-fold more esterified 15-hydroxyeicosatetraenoic acid (15-HETE) than free in a phosphatidylinositol 3-kinase- and protein kinase C-sensitive manner. Precursor scanning electrospray ionization/tandem spectroscopy for m/z 319 (HETE, [M-H](-)) showed 4 ions at m/z 738, 764, 766, and 782 that were identified using tandem spectroscopy and MS3 as specific diacyl and plasmalogen 15-HETE phosphatidylethanolamines. Using H (18)(2)O water, the compounds were shown to form by direct oxidation of endogenous phosphatidylethanolamine (PE) by 15-LOX, with PE being the preferred phospholipid pool containing 15-HETE. Similarly, human platelets generated 4 analogous PE lipids that contained 12-HETE and increased significantly in response to ionophore, collagen, or convulxin. These products were retained in the cells, in contrast to free acids, which are primarily secreted. Precursor scanning of platelet extracts for the major platelet-derived prostanoid, thromboxane B2 (m/z 369.2), did not reveal PE esters, indicating that this modification is restricted to the LOX pathway. In summary, we show formation of PE-esterified HETEs in immune cells that may contribute to LOX signaling in inflammation.
Maskrey
Benjamin H
BH
Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Heath Park, Cardiff, Wales, United Kingdom.
Bermúdez-Fajardo
Alexandra
A
Morgan
Alwena H
AH
Stewart-Jones
Esther
E
Dioszeghy
Vincent
V
Taylor
Graham W
GW
Baker
Paul R S
PR
Coles
Barbara
B
Coffey
Marcus J
MJ
Kühn
Hartmut
H
O'Donnell
Valerie B
VB
D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000276:immunology / Q000378:metabolism; D001092:Arachidonate 12-Lipoxygenase / Q000276:immunology / Q000378:metabolism*; D001093:Arachidonate 15-Lipoxygenase / Q000276:immunology / Q000378:metabolism; D001792:Blood Platelets / Q000201:enzymology* / Q000276:immunology; D018920:Coculture Techniques; D003094:Collagen / Q000494:pharmacology; D003435:Crotalid Venoms / Q000494:pharmacology; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000276:immunology / Q000378:metabolism; D015847:Interleukin-4 / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D037181:Lectins, C-Type; D009000:Monocytes / Q000201:enzymology* / Q000276:immunology; D010084:Oxidation-Reduction / Q000187:drug effects; D010714:Phosphatidylethanolamines / Q000276:immunology / Q000378:metabolism*; D015539:Platelet Activation / Q000187:drug effects / Q000276:immunology; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D021241:Spectrometry, Mass, Electrospray Ionization
D003435:Crotalid Venoms; D006893:Hydroxyeicosatetraenoic Acids; C508598:IL4 protein, human; D007476:Ionophores; D037181:Lectins, C-Type; D010714:Phosphatidylethanolamines; D015847:Interleukin-4; C028890:convulxin; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D003094:Collagen; D001092:Arachidonate 12-Lipoxygenase; D001093:Arachidonate 15-Lipoxygenase