There are five different lipoproteins:
*chylomicrons,
*very low-density lipoproteins (VLDL),
*intermediate density lipoproteins (IDL),
*low-density lipoproteins (LDL) and
*high-density lipoproteins (HDL)
Low-density lipoprotein (LDL) transports cholesterol in the bloodstream and plays an important role in the development of cardiovascular diseases, in particular atherosclerosis.
Whereas LDL particles carry about two-thirds of plasma cholesterol and can infiltrate the arterial wall leading to atherosclerosis, HDL particles are antiatherogenic as their role is to deliver cholesterol to the liver to be metabolized and eliminated.
On average, LDL particles have a diameter of 22 nm and contain ~3000 lipids. Their density ranges between 1.019 and 1.063 g/ml, highlighting that quite a heterogeneous group of particles can be called LDL. Most abundant lipid species in LDL are triglycerides and cholesteryl esters assumed to reside in the core of the particle, while different phospholipids are expected to be located on the surface.
In the initial stages of atherogenesis, LDL-derived lipids accumulate in the arterial intima, and high LDL levels have been shown to increase the risk of atherosclerosis. This together with formation of plaque on arterial walls leads to the narrowing of arteries, rupture, clotting, and potential death.
Since most of the cholesterol in serum is transported via LDL, measuring serum LDL levels could be useful to predict the risk for atherosclerotic cardiovascular diseases.
A predominance of small, dense LDLs is seen in patients with ischaemic heart disease and non-insulin-dependent diabetes, and is more common in men than in women. Because small, dense LDLs are associated with increased levels of triglyceride and low levels of high-density-lipoprotein cholesterol.
Low-density lipoprotein
