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Lipoprotein(a), plasmin modulation, and atherogenesis
P C Harpel1, A Hermann, X Zhang
1Department of Medicine, Mount Sinai Medical Center, New York, NY 10029, USA.
Thrombosis and Haemostasis
|July 1, 1995
Summary
Lipoprotein(a) [Lp(a)] contributes to atherosclerosis by affecting blood clot breakdown and cell growth. Lp(a) may promote artery disease by altering plasmin and TGF-beta production in blood vessel walls.
Area of Science:
- Cardiovascular Biology
- Lipid Metabolism
- Atherosclerosis Research
Background:
- Lipoprotein(a) [Lp(a)] is an atherogenic lipoprotein implicated in cardiovascular disease.
- The precise mechanisms by which Lp(a) promotes atherosclerosis remain incompletely understood.
- The apolipoprotein(a) [apo(a)] component of Lp(a) shares homology with plasminogen, suggesting interactions with the fibrinolytic system.
Purpose of the Study:
- To elucidate the mechanisms underlying Lp(a)-mediated atherogenesis.
- To investigate the impact of Lp(a) on fibrin binding, plasminogen activation, and transforming growth factor-beta (TGF-beta) production.
- To assess the role of Lp(a) in smooth muscle cell behavior and in vivo atherogenic processes.
Main Methods:
- In vitro studies examining Lp(a) interactions with fibrin and its effects on plasminogen activation under varying conditions.
- Cell coculture systems to evaluate Lp(a)-induced changes in TGF-beta production and smooth muscle cell migration/proliferation.
- Studies using transgenic mice expressing the human apo(a) gene to assess in vivo effects on aortic plasmin and TGF-beta formation.
Main Results:
- Lp(a) exhibits variable effects on in vitro plasmin formation, either promoting or inhibiting it depending on experimental conditions.
- Lp(a) inhibits cell-surface dependent plasmin generation, leading to reduced TGF-beta production.
- Lp(a) stimulates smooth muscle cell migration and proliferation, potentially as a consequence of decreased TGF-beta.
- Transgenic mouse studies demonstrate significantly reduced aortic plasmin and TGF-beta formation in the presence of apo(a).
Conclusions:
- Lp(a)'s atherogenicity may be partly mediated by its modulation of plasmin and TGF-beta production within the blood vessel wall.
- Lp(a) influences key components of the fibrinolytic system and cellular processes involved in atherosclerotic plaque development.
- Understanding these mechanisms provides insight into Lp(a)-associated cardiovascular risk.