Cholesterol is carried in the blood from place to place on special particles called lipoproteins. One kind of lipoprotein particle, low-density lipoprotein or LDL, carries cholesterol to different parts of the body, including the walls of arteries, and can lead to problems when it carries more cholesterol than cells require to function normally. Another kind, high-density lipoprotein or HDL, carries cholesterol away from the artery walls and eventually out of the body. There is a direct link between elevated levels of LDL and atherosclerosis and decreased levels of HDL, which are protective. The first was the discovery that a part of the artery called the endothelium plays a major role.
Arteries consist of three distinct layers.
The innermost layer is called the intima. The endothelium, which is only a single cell thick, comprises the lining of that innermost layer and acts as an interface between blood and arterial wall. The second breakthrough was that atherosclerosis appears to be a healing response by the body that goes haywire. When any part of the body is damagedwhether by infection with bacteria, sports injury, a burn, etc.the body increases the flow of blood to the injured area and puts white blood cells to work there. White blood cells surround the bacteria or the damaged tissue.