The role of lipoprotein(a) in atherogenesis and thrombosis.

Lipoprotein(a) [Lp(a)] represents an important independent risk factor for atherosclerotic cardiovascular disease. Lp(a) constitutes a class of low-density lipoprotein-like particles that are structurally heterogeneous due to variability within the distinguishing apoprotein, apolipoprotein(a) [Apo(a)]. Apo(a) bears a high degree of homology to the fibrinolytic zymogen, plasminogen, the parent molecule of the serine protease plasmin. Apo(a) contains a variable number of tandemly repeated triple-loop units called kringles, which appear to mediate Lp(a)'s interactions with fibrin and cell surface receptors. Although the mechanism of its atherogenicity is unknown, Lp(a) has been implicated in the delivery of cholesterol to the injured blood vessel, in blockade of plasmin generation on fibrin and cell surfaces, and as a stimulus for smooth muscle cell proliferation. In addition, new members of the plasminogen/Apo(a) gene family have been defined, creating a potential link between Lp(a) and the control of angiogenesis in both health and disease. Pharmacologic therapy of elevated Lp(a) levels has been only modestly successful; apheresis remains the most effective therapeutic modality.