chylomikronide

Chylomikronide is a lipoprotein particle formed in the enterocytes of the small intestine that transports dietary lipids, especially triglycerides, from the intestinal lumen into the circulation. In many languages the term corresponds to what is commonly called a chylomicron in English. Chylomikronide particles are among the largest and least dense lipoproteins found in blood after a fat-rich meal.

The surface of a chylomikronide is composed of phospholipids and cholesterol, enclosing a core rich in triglycerides and cholesteryl esters. Its apolipoprotein content is characteristic, with apolipoprotein B-48 as the central scaffold, and additional apolipoproteins such as ApoC and ApoE that are acquired from plasma as the particle circulates. The particle is assembled in the endoplasmic reticulum of enterocytes with the help of microsomal triglyceride transfer protein (MTP) and becomes a nascent chylomicron, which is secreted into the lymphatic system and eventually enters the bloodstream.

In circulation, chylomikronide triglycerides are hydrolyzed by lipoprotein lipase (LPL) in capillary beds, aided by ApoC-II, releasing fatty acids for use by tissues or storage. The remnant particle, enriched in cholesterol esters, is cleared from the bloodstream mainly by hepatic receptors that recognize ApoE.

Clinical relevance includes disorders of chylomicron metabolism. For example, abetalipoproteinemia and familial chylomicronemia syndrome involve defective chylomikronide formation or clearance, leading to elevated triglycerides and associated symptoms such as pancreatitis and fat-soluble vitamin deficiencies.