© 2003 by European Society of Cardiology
Copyright © 2003, European Society of Cardiology
Paraoxonase-1 reduces monocyte chemotaxis and adhesion to endothelial cells due to oxidation of palmitoyl, linoleoyl glycerophosphorylcholine
aJ. Alick Little Lipid Research Laboratory, St. Michael's Hospital, Room 1004 WA, 38 Shuter Street, Toronto, Ont., Canada M5B 1A6
bDepartment of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ont., Canada
cTerrence Donnelly Vascular Biology Laboratory, St. Michael's Hospital, Toronto, Ont., Canada
dBanting and Best Department of Medical Research, University of Toronto, Toronto, Ont., Canada
eDepartment of Biochemistry, University of Toronto, Toronto, Ont., Canada
fDepartment of Medicine, University of Toronto, Toronto, Ont., Canada
gDepartment of Pharmacology, University of Michigan, Ann Arbor, MI, USA
hDepartment of Pathology and Laboratory Medicine, University of Louisville Medical Center, Louisville, KY 40202, USA
* Corresponding author. Present address: J. Alick Little Lipid Research Laboratory, St. Michael's Hospital, Room 1004 WA, 38 Shuter Street, Toronto, Ont., Canada M5B 1A6. Tel.: +1-416-864-6023; fax: +1-416-864-5870. connellyp{at}smh.toronto.on.ca
Objective: High-density lipoprotein (HDL) is postulated to protect against the development of atherosclerosis, in part, by inhibiting the oxidation of low density lipoprotein (LDL) in the sub-endothelial space and thus inhibiting activation of the endothelium. The HDL-associated enzyme, paraoxonase-1, is proposed to be a major protective factor. However, HDL is also prone to oxidation when exposed to peroxynitrite and may therefore, once oxidized, have properties similar to oxidized LDL. Methods and results: We exposed human HDL to the peroxynitrite donor 3-morpholinosydnonimine and incubated oxidized HDL with human umbilical vein endothelial cells (HUVECs). Oxidized HDL increased monocyte binding (P<0.001) and enhanced chemotaxis (P<0.001). The major oxidized phospholipids were 1-palmitoyl (stearoyl)-2-[9-oxo]nanoyl(azelaoyl)-sn-glycero-phosphocholine, derived from linoleate-containing phosphatidylcholines, and 1-palmitoyl(stearoyl)-2-[5-oxo]valeroyl(glutaroyl)-sn-glycero-phosphocholine, derived from arachidonate-containing phosphatidylcholines. Incubation of HUVECs with synthetically prepared 1-palmitoyl-2-[9-oxo]nanoyl(azelaoyl)-sn-glycero-phosphocholine, or 1-palmitoyl-2-[5-oxo]valeroyl(glutaroyl)-sn-glycero-phosphocholine increased binding of monocytes (P<0.001) and chemotaxis (P<0.001). Purified paraoxonase-1 reduced monocyte adhesion and chemotaxis (P<0.001). Conclusions: (i) HDL can be a source of oxidatively-derived bioactive phospholipids; (ii) the fragmented phospholipids with a 9-carbon aldehyde or acid are as effective as a 5-carbon aldehyde or acid at inducing monocyte adhesion and chemotaxis; and (iii) paraoxonase-1 is effective at reducing the activity of these phospholipid oxidation products.
KEYWORDS apoA-I, apolipoprotein A-I; HDL, high density lipoproteins; HPF, high powered field; HUVECs, human umbilical vein endothelial cells; LC–ESI-MS, liquid chromatography–electrospray ionization-mass spectrometry; LDL, low density lipoproteins; PAPC, 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine; PAzPC, 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine; PC, phosphatidylcholine; PGPC, 1-palmitoyl-2-(glutaroyl)-sn-glycero-phosphocholine; PLPC, 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine; PON-1, paraoxonase-1; PONPC, 1-palmitoyl-2-(9-oxo)nonanoyl-sn-glycero-3-phosphocholine; POVPC, 1-palmitoyl-2-[5-oxo]valeroyl-sn-glycero-phosphocholine; SGPC, 1-stearoyl-2-(glutaroyl)-sn-glycero-phosphocholine; SIN-1, 3-morpholinosydnonimine; SOVPC, 1-stearoyl-2-[5-oxo]valeroyl-sn-glycero-phosphocholine