Epoxyisoprostane and epoxycyclopentenone phospholipids regulate monocyte chemotactic protein-1 and interleukin-8 synthesis. Formation of these oxidized phospholipids in response to interleukin-1beta.
Monocyte recruitment to the vessel wall, mediated by monocyte chemotactic protein-1 (MCP-1) and interleukin-8 (IL-8), plays an important role in atherogenesis. We have shown previously that minimally oxidized low density lipoprotein, oxidized 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphorylcholine (Ox-PAPC), activates endothelial cells to produce MCP-1 and IL-8. By using liquid chromatography/mass spectrometry methods coupled with bioassay, we report a family of epoxyisoprostane (PEIPC) and epoxycyclopentenone (PECPC) phospholipids that are the components of Ox-PAPC responsible for the majority of this activity. Ox-PAPC contains five chromatographically distinguishable active PEIPC components (m/z 825.5) and four PECPC components (m/z 810.5). All nine components induced endothelial cell synthesis of IL-8 and MCP-1 in a dose-dependent fashion between 0.1 and 5 microm concentrations. The five PEIPC components had identical functional groups and all underwent dehydration to produce m/z 810.5. We present evidence that these phospholipids are regioisomers with epoxide groups at the 5,6-, 8,9-, 11,12-, or 14,15-positions of the sn-2 fatty acid and their epoxide groups is important for biological activity. We have shown previously that peroxisome proliferator-activated receptor alpha is involved in MCP-1 synthesis in response to Ox-PAPC. We now show that PEIPC and PECPC isomers are potent activators of peroxisome proliferator-activated receptor alpha. PEIPC and PECPC isomers are strongly recognized by specific circulating murine natural autoantibodies (EO6) and accumulate in cells treated with IL-1beta. These studies demonstrate that PEIPC and PECPC isomers are potent activators of endothelial cells increasing synthesis of IL-8 and MCP-1. Their accumulation in cells exposed to cytokines and in atherosclerotic lesions suggests that these lipids may play a role in a number of chronic disease processes.
Subbanagounder
Ganesamoorthy
G
Department of Medicine, Center for the Health Sciences, Rm. 47-123, UCLA Medical Center, Los Angeles, CA 90095-1679, USA. gsubbanagounder@mednet.ucla.edu
Wong
Jason W
JW
Lee
Hans
H
Faull
Kym F
KF
Miller
Elizabeth
E
Witztum
Joseph L
JL
Berliner
Judith A
JA
D001667:Binding, Competitive; D002460:Cell Line; D018932:Chemokine CCL2 / Q000096:biosynthesis*; D003517:Cyclopentanes / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D004789:Enzyme Activation; D008401:Gas Chromatography-Mass Spectrometry; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D006868:Hydrolysis; D007375:Interleukin-1 / Q000378:metabolism; D016209:Interleukin-8 / Q000096:biosynthesis*; D028421:Isoprostanes / Q000378:metabolism*; D050356:Lipid Metabolism; D008163:Luminescent Measurements; D013058:Mass Spectrometry; D008956:Models, Chemical; D010100:Oxygen / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D018932:Chemokine CCL2; D003517:Cyclopentanes; D007375:Interleukin-1; D016209:Interleukin-8; D028421:Isoprostanes; D010743:Phospholipids; D018160:Receptors, Cytoplasmic and Nuclear; D014157:Transcription Factors; C013905:cyclopentenone; D010100:Oxygen