LDL particle subclasses in hypercholesterolemia. Molecular determinants of reduced lipid hydroperoxide stability.
Hypercholesterolemia is characterized by elevated plasma levels of LDL in which the cholesteryl ester (CE)-rich LDL subclasses of light and intermediate density (LDL1+2 and LDL3, respectively) typically predominate. The molecular mechanisms implicated in oxidation of LDL particle subclasses in hypercholesterolemia are indeterminate. Lipid hydroperoxides (LOOH), primary oxidation products in LDL, are implicated in atherogenesis. LOOH formation was evaluated in light (LDL1+2), intermediate (LDL3), and dense (LDL4+5) LDL subclasses from hypercholesterolemic (HC) subjects (n = 7) during copper-mediated oxidative stress, and compared with that in corresponding subclasses from normolipidemic subjects (n = 7). HC LDL subclasses were distinguished by lower polyunsaturated phospholipid-alpha-tocopherol ratios (P < 0.02), lower contents of phosphatidyl choline (PC)16:0-18:0/18:2 and PC16:0-18:0/20:4+22:6 (P < 0.002), and higher surface phospholipid-free cholesterol ratios (P < 0.04). The LDL3, LDL4, and LDL5 subclasses in HC subjects displayed low-core polyunsaturated CE-alpha-tocopherol ratios (P < 0.05), despite similar PUFA CE content. These physicochemical differences did not modify the oxidative susceptibility of HC LDL but underlie the marked instability of cholesterol linoleate hydroperoxides in HC LDL1+2, LDL3, and LDL4 subclasses. Elevated concentrations of large, CE-rich, light, and intermediate LDL subclasses (LDL1+2, LDL3) in hypercholesterolemia may therefore act as an abundant proatherogenic source of highly unstable LOOH in the arterial wall.
Chancharme
Laurent
L
Institut National de la Santé et de la Recherche Médicale (INSERM) U551, Pavillon Benjamin Delessert, Hôpital de la Pitié, 83 Blvd l'Hôpital, 75651 Paris Cedex 13, France.
Thérond
Patrice
P
Nigon
Fabienne
F
Zarev
Stéphanie
S
Mallet
Alain
A
Bruckert
Eric
E
Chapman
M John
MJ
D053299:Apolipoprotein B-100; D001055:Apolipoproteins B / Q000378:metabolism; D002788:Cholesterol Esters / Q000097:blood / Q000378:metabolism; D003300:Copper / Q000378:metabolism; D004951:Esterification; D005227:Fatty Acids / Q000097:blood; D005231:Fatty Acids, Unsaturated / Q000097:blood / Q000378:metabolism; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood*; D008054:Lipid Peroxides / Q000097:blood / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000097:blood* / Q000737:chemistry / Q000378:metabolism; D008297:Male; D010084:Oxidation-Reduction; D010316:Particle Size; D010713:Phosphatidylcholines / Q000097:blood / Q000378:metabolism; D010743:Phospholipids / Q000097:blood
D053299:Apolipoprotein B-100; D001055:Apolipoproteins B; D002788:Cholesterol Esters; D005227:Fatty Acids; D005231:Fatty Acids, Unsaturated; D008054:Lipid Peroxides; D008077:Lipoproteins, LDL; D010713:Phosphatidylcholines; D010743:Phospholipids; D003300:Copper