Characterization of the cholesterol efflux of apolipoprotein E-containing high-density lipoprotein

What is it about?

High-density lipoprotein (HDL) is known to be good lipoprotein because it has various capacities to prevent atherosclerosis which would lead to heart disease. One of anti-atherosclerotic capacity is cholesterol efflux capacity (CEC) which enable HDL to pull cholesterol from cholesterol-accumulated cells (called foam cells) which induce atherosclerosis. Therefore, many researchers have been trying to increase the level of this good lipoprotein by medicine. In fact, some studies showed HDL level in blood was successfully increased by a drug named a cholesteryl ester transfer protein (CETP) inhibitor but the mortality rate of heart disease wasn't improved. One of the reason might be caused by a type of the increased HDL. HDL is not a single type of lipoprotein. Many kinds of HDL exist in our blood. Apolipoprotein E (apoE)-containing HDL is one of minor HDLs and it was found that the type of HDL which was increased by CETP inhibitor is this apoE-containing HDL. Therefore, to characterize the function of apoE-containing HDL is important. Here, we investigated CEC in apoE-containing HDL. We found that apoE-containing HDL also has CEC but the mechanism of CEC (pathway) was different from normal HDL.

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Why is it important?

Cardiovascular disease is one of the leading causes of death in developed countries so that prevention of this disease is urgently required. Although many researchers have been paying attention to a therapy for increasing HDL level, it has not succeeded. Our findings shows that apoE-containg HDL has different mechanism in cholesterol efflux (pick up cholesterol from cells) compared to normal HDL. It might be one of clue to explain why these therapies didn't get good outcome.

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