Phagocyte oxidation of phospholipids: comparison of hydroperoxide, chlorohydrin and epoxyisoprostane formation by LC-MS

Corinne M. Spickett, Andreas Jerlich, R. Jörg Schaur, Andrew R. Pitt

Research output: Contribution to journalConference abstract

Abstract

Phagocytic cells produce a variety of oxidants as part of the immune defence, which react readily both with proteins and lipids, and could contribute to the oxidation of low density lipoprotein in atherosclerosis. We have investigated the oxidation of phospholipid vesicles by isolated human polymorphonuclear and mononuclear leukocytes, to provide a model of lipid oxidation in the absence of competing protein. PMA-stimulated cells were incubated with phospholipid vesicles contammg dipalmitoyl phosphatidylcholine (DPPC), palmitoyl-arachidonoyl phosphatidylcholine (PAPC), and stearoyl-oleoyl phosphatidylcholine (SOPC), before extraction of the lipids for analysis by HPLC coupled to electrospray mass spectrometry. In this system, oxidized phosphatidylcholines elute earlier than the native lipids owing to their decreased hydrophobicity, and can be identified according to their molecular mass. The formation of monohydroperoxides of P APC was observed routinely, together with low levels of hydroxides, but no chlorohydrin derivatives of P APC or SOPC were detected. However, the major oxidized product occurred at 828 m/z, and was identified as I-palmitoyl-2-(5,6-epoxyisoprostane E2)-sn-glycero-3-phosphocholine. These results show that phagocytes triggered by PMA cause oxidative damage to lipids predominantly by free radical mechanisms, and that electrophilic addition involving HOCl is not a major mechanism of attack. The contribution of myeloperoxidase and metal ions to the oxidation process is currently being investigated, and preliminary data suggest that myeloperoxidase-derived oxidants are responsible for the epoxyisoprostane phospholipid formation. The identification of an epoxyisoprostane phospholipid as the major product following phagocyte-induced phospholipid oxidation is novel and has implications for phagocyte involvement in atherogenesis.
Original languageEnglish
Article number379
Pages (from-to)S145
Number of pages1
JournalFree Radical Biology and Medicine
Volume33
Issue number2, Suppl.1
Early online date29 Jun 2002
DOIs
Publication statusPublished - 15 Jul 2002
Event11th Meeting of the Society for Free Radical Research International - Paris, France
Duration: 16 Jul 2002 → …

Keywords

  • phagocyte oxidation
  • phospholipids
  • hydroperoxide
  • chlorohydrin
  • epoxyisoprostane
  • pharmacy and materia medica

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    Luminescent techniques for studying free radical production and cell viability in relation to cardiovascular disease and HRT

    Lateef, S., Walker, J. J. & Spickett, C. M., 15 Jul 2002, In : Free Radical Biology and Medicine. 33, 2, Suppl.1, p. S28 1 p., 65.

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  • The antioxidant potential of modified quercetins and quercetin-metal complexes

    Spickett, C. M., Wojton, A., Kopacz, M. & Oleksyn, B., 15 Jul 2002, In : Free Radical Biology and Medicine. 33, 2, Suppl.1, p. S209-S210 2 p., 556.

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