Low-density lipoprotein

Low-density lipoprotein

Atheroma formation in an artery

Low-density lipoprotein (LDL) is one of the five major groups of lipoproteins that transport all fat molecules throughout the body in the extracellular water. These groups, from least dense to most dense, are chylomicrons, very low-density lipoproteins (VLDL), intermediate-density lipoproteins (IDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL).

Structure

LDL particles are the major carriers of cholesterol in the blood. They are composed of a core of cholesteryl esters and triglycerides, surrounded by a shell of phospholipids, free cholesterol, and apolipoprotein B-100. The size of LDL particles can vary, and smaller, denser LDL particles are considered more atherogenic.

Function

The primary role of LDL is to transport cholesterol to peripheral tissues. Cells express LDL receptors on their surface, which bind to the apolipoprotein B-100 on LDL particles, allowing them to be internalized and utilized for membrane synthesis and other functions.

Clinical significance

Elevated levels of LDL cholesterol are associated with an increased risk of atherosclerosis, a condition characterized by the buildup of fatty deposits, or plaques, within the walls of arteries. This can lead to coronary artery disease, stroke, and other cardiovascular diseases.

Atheroma formation

Atheroma formation in an artery

Atheromas, or plaques, form when LDL particles penetrate the endothelial lining of arteries and become oxidized. This triggers an inflammatory response, attracting macrophages that engulf the oxidized LDL, becoming foam cells. Over time, these foam cells accumulate, forming the core of the atheroma.

Management

Management of elevated LDL cholesterol involves lifestyle modifications such as diet and exercise, as well as pharmacological interventions. Statins are the most commonly prescribed medications for lowering LDL cholesterol levels. Other medications include ezetimibe, PCSK9 inhibitors, and bile acid sequestrants.

Related pages

• High-density lipoprotein
• Cholesterol
• Atherosclerosis
• Cardiovascular disease