APOE and atherosclerosis: Moreover, adenovirus-mediated gene transfer of the human paraoxonase 1 (PON1), an HDL-associated enzyme that destroys lipid peroxides, into aged apoE-/- mice with advanced atherosclerosis, decreased the oxLDL content of the plaques and restored endothelial function in plaque-bearing but not in plaque-free segments of the thoracic aorta [67].