Protein targets of oxidized phospholipids in endothelial cells

Oxidation products of 1-palmitoyl-2-arachidonoyl- sn-glycero-3-phosphatidylcholine (Ox-PAPC) are found in atherosclerotic lesions, apoptotic cells, and oxidized LDL and stimulate human aortic endothelial cells (HAECs) to produce inflammatory cytokines, leukocyte chemoattrac- tants, and coagulation factors. This regulation is thought to be a receptor-mediated process in which oxidized phos- pholipids activate specific receptors on HAECs to evoke an inflammatory response. To characterize the HAEC proteins with which oxidized phospholipids interact, a biotinylated PAPC analog, 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phos- phatidyl-(N-biotinylethanolamine) (PAPE-N-biotin), was syn- thesized. Oxidation of PAPE-N-biotin in air generated a mixture of biotin-labeled oxidized lipids analogous to Ox- PAPC. Ox-PAPE-N-biotin, like Ox-PAPC, induced inter- leukin-8 (IL-8) protein synthesis and stimulated IL-8, low density lipoprotein receptor, heme oxygenase-1, and activat- ing transcription factor-3 mRNA expression in HAECs. After treatment of HAECs with Ox-PAPE-N-biotin, the cellular proteins were isolated and separated by SDS-PAGE. Western analysis with streptavidin-HRP demonstrated at least 20 differentbiotinylatedHAECproteinstowhichtheOx-PAPE- N-biotin was associated, which were not detected with un- oxidized PAPE-N-biotin treatment. This work suggests thatoxidizedphospholipids, suchasthosefoundinoxidized LDL, apoptotic cells, and atherosclerotic lesions, form tight interactions with specific endothelial cell proteins, which may be responsible for the inflammatory response. Identi- fication of these putative oxidized phospholipid targets may reveal therapeutic targets to modulate inflammation and atherosclerosis.—Gugiu, B. G., K. Mouillesseaux, V. Duong, T. Herzog, A. Hekimian, L. Koroniak, T. M. Vondriska, and A. D. Watson. Protein targets of oxidized phospholipids in endothelial cells. J. Lipid Res. 2008. 49: 510-520.