Increased atherosclerotic lesions in apoE mice with plasma phospholipid transfer protein overexpression

Plasma phospholipid transfer protein (PLTP) is involved in the metabolism of HDL and apolipoprotein B (apoB)-containing lipoproteins. Atherosclerosis susceptibility is decreased in mice with PLTP deficiency that is associated with decreased liver production of apoB-containing lipoproteins and increase in their antioxidant. To investigate additionally the effect of PLTP on the development of atherosclerosis, we overexpressed PLTP in mice.

PLTP was overexpressed in apoE knockout mice using an adenovirus-associated virus (AAV)-mediated system. Plasma PLTP activity was 1.3- to 2-fold higher in mice injected with AAV-PLTP than in mice injected with control AAV-GFP, and PLTP levels were sustained during the experiment period (4 months). We show that 2-fold increased PLTP activity results in (1) a decrease in HDL cholesterol, HDL phospholipid, and apoAI levels; (2) a decrease in vitamin E contents in total plasma and in individual lipoprotein fractions; (3) an increase in lipoprotein oxidizability as assessed by copper-induced formation of conjugated dienes; (4) an increase in autoantibodies against oxidized apoB-containing particles; and (5) an increase in atherosclerosis lesions in proximal aorta.

These observations indicate that elevated plasma PLTP levels constitute a novel, long-term risk factor for atherosclerosis.