Lipoprotein (a)

Lipoprotein (a) is a risk factor for cardiovascular disease.

Lipoprotein (a) (lipoprotein “a” is small, LP (a); English Lipoprotein (a), Lp (a) ) is a subclass of lipoproteins of human blood plasma . It is a risk factor for coronary heart disease and other cardiovascular diseases. It has a high polymorphism in its protein component apolipoprotein (a) and high concentration heterogeneity in the blood. It is also found in primates and some other animals. The physiological role is unknown.

Content

Structure

Particle LP (a) in structure and lipid composition is similar to the particle LDL . It also contains apoB-100 , but, unlike LDL, apoB-100 is associated with an additional protein, apolipoprotein (a). Apolipoprotein (a) (apo (a)) is a large hydrophilic and highly glycosylated protein that is similar in composition to plasminogen . Consists of several repetitive fragments consisting of about 80 amino acids . Apo (a) is very different from person to person in molecular weight (from 300 to 800 kDa) and the level of synthesis . It is assumed that the apo (a) gene occurred as a result of repeating certain parts of the plasminogen gene, both genes being closely related to each other. Apo (a) is synthesized in the liver and is bound by a disulfide bond to the newly synthesized apoB-100. Since both proteins interact with their C-terminal sites, apoB loses affinity for its receptor ( LDL receptor ).

Level in different populations

The level of LP (a) in the blood varies greatly (from <0.2 to> 200 mg / dL) and is mainly determined by heredity . Africans are characterized by a higher concentration of LP (a), which on average is 7 times higher than the level of LP (a) in the European and Asian populations.

Role in pathology

A high level of LP (a) is a risk factor for coronary heart disease , atherosclerosis , thrombosis and stroke . Since the level of lipoprotein (a) is determined genetically, factors such as diet and exercise practically do not affect it. The only effective way to reduce the LP (a) in the blood is the use of extracorporeal treatment methods, such as cascade plasma filtration, heparin-LDL precipitation (HELP). A high level of LP (a), like a high level of LDL, predetermines the risk of developing early atherosclerosis. Since the LP (a) is structurally very close to plasminogen, the LP (a) has a high affinity for the extracellular matrix and quickly accumulates in the vascular wall. Further, the protein undergoes oxidation and partial proteolysis under the action of metalloproteases , which causes the development of atheromatous plaque.

Human blood concentration

Test: Lipoprotein (a) / LP (a)

Rate: <14 mg / dL

Low risk: 14-30 mg / dL

High risk: 31-50 mg / dL

Very high risk:> 50 mg / dL

Links

Beyond Cholesterol, Julius Torelli MD, 2005 ISBN 0-312-34863-0 page 91.
Hidden Causes of Heart Attack and Stroke, Christian Wilde, 2003 ISBN 0-9724959-0-8 pages 182-183.