High-density lipoprotein from hypercholesterolemic animals has peroxidized lipids and oligomeric apolipoprotein A-I: its putative role in atherogenesis.

Oxidized lipoproteins have been involved in the pathogenesis of atherosclerosis and atherosclerotic lesions contain oxidized low density lipoprotein. Conversely, the presence of oxidized high density lipoprotein (HDL) in vivo has not been clearly established. Oxidation of HDL in vitro models produces an increase in peroxidized lipids and the appearance of apolipoprotein A-I (apo A-I) oligomers. We investigated the oxidative status of HDL in an in vivo model: the hypercholesterolemic chicken. The HDLs from control and hyperlipemic animals were analyzed for the content of lipid peroxides employing spectroscopic and fluorescence techniques, for the level of apo A-I oligomerization, and for susceptibility to in vitro oxidation. HDL from hypercholesterolemic chickens was more peroxidized (as detected by fluorescence), had higher amount of oligomeric apo A-I, and was oxidized to a greater extent by uv irradiation than that of control animals. We speculate that apo A-I oligomerization could be a key step in the atheroma formation.