Which lipoprotein transports cholesterol from peripheral tissues back to the liver?

Which lipoprotein transports cholesterol from peripheral tissues back to the liver?

• A. Lipoproteins that carry triglycerides from liver to tissues
• B. Lipoproteins that transport cholesterol from peripheral tissues back to the liver
• C. Lipoproteins that transport cholesterol from tissues to arteries
• D. Lipoproteins that transport dietary fats

Answer: (B)

The key idea is reverse cholesterol transport. This is the process by which HDL collects cholesterol from cells in peripheral tissues (such as macrophages in arterial plaques) and returns it to the liver for disposal or reuse. It starts with cholesterol leaving cells and transferring to HDL particles via transporters like ABCA1, forming nascent HDL. LCAT then esterifies the free cholesterol on HDL, allowing it to mature and carry cholesterol esters in its core. When HDL reaches the liver, hepatocytes take up the cholesteryl esters (often via the SR-BI receptor) for bile acid synthesis or excretion. CETP can exchange cholesteryl esters from HDL to other lipoproteins, but the overall function remains removing cholesterol from peripheral tissues and delivering it to the liver. Other lipoproteins mainly move triglycerides to tissues or dietary fats from the intestines, not cholesterol back to the liver, so they don’t serve this return pathway.

The key idea is reverse cholesterol transport. This is the process by which HDL collects cholesterol from cells in peripheral tissues (such as macrophages in arterial plaques) and returns it to the liver for disposal or reuse. It starts with cholesterol leaving cells and transferring to HDL particles via transporters like ABCA1, forming nascent HDL. LCAT then esterifies the free cholesterol on HDL, allowing it to mature and carry cholesterol esters in its core. When HDL reaches the liver, hepatocytes take up the cholesteryl esters (often via the SR-BI receptor) for bile acid synthesis or excretion. CETP can exchange cholesteryl esters from HDL to other lipoproteins, but the overall function remains removing cholesterol from peripheral tissues and delivering it to the liver. Other lipoproteins mainly move triglycerides to tissues or dietary fats from the intestines, not cholesterol back to the liver, so they don’t serve this return pathway.