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Hyperhomocysteinemia, vascular pathology, and endothelial dysfunction
C van Guldener1, C D Stehouwer
1Department of Internal Medicine, University Hospital and Institute for Cardiovascular Research Vrije Universiteit, Amsterdam, The Netherlands. CDA.stehouwer@azvu.nl
Insights
High homocysteine levels are linked to early vascular disease, but the exact mechanisms and effects of lowering homocysteine on vascular health remain unclear. Further research is needed to understand its impact on endothelial function and clinical outcomes.
Area of Science:
- Cardiovascular Science
- Metabolic Disease Research
- Vascular Biology
Background:
- Hyperhomocysteinemia is associated with premature atherothrombotic vascular disease.
- The specific mechanisms by which homocysteine contributes to vascular disease are not fully understood.
- The interaction between hyperhomocysteinemia and traditional cardiovascular risk factors is unclear.
Purpose of the Study:
- To investigate whether hyperhomocysteinemia induces a distinct type of vascular disease.
- To clarify the pathophysiological mechanisms linking homocysteine to vascular disease in vivo.
- To determine the effects of homocysteine-lowering treatment on vascular function and clinical endpoints.
Main Methods:
- In vitro and animal studies suggest homocysteine affects nitric oxide bioavailability, oxidative stress, and smooth muscle cell proliferation.
- Clinical studies examining the relationship between plasma homocysteine and endothelial function indices have yielded controversial results.
- Controlled data on the impact of homocysteine-lowering interventions on vascular function and clinical outcomes are lacking.
Main Results:
- Proposed mechanisms include reduced nitric oxide bioavailability, increased oxidative stress, and altered vascular wall properties.
- In vivo relevance of these mechanisms is uncertain due to conflicting clinical findings.
- Lack of controlled trials prevents definitive conclusions on treatment effects.
Conclusions:
- The precise mechanisms of homocysteine's adverse vascular effects are unknown.
- Potential mechanisms involve impaired endothelial and smooth muscle cell function.
- Further controlled studies are required to elucidate the role of homocysteine in vascular disease and the efficacy of lowering treatments.
Abstract:
Hyperhomocysteinemia has been associated with premature atherothrombotic vascular disease. It is not known whether hyperhomocysteinemia induces a distinct type of vascular disease. Its interaction, if any, with traditional risk factors also remains unclear. The pathophysiological mechanisms linking hyperhomocysteinemia to vascular disease have been extensively studied in vitro and in animals. From these studies, it has been suggested that homocysteine limits the bioavailability of nitric oxide (NO), increases oxidative stress, stimulates smooth cell proliferation, and alters elastic wall properties. The relevance of these proposed mechanisms in vivo is unclear, because clinical studies have yielded controversial results with regard to the relation between plasma homocysteine levels and indices of endothelial function, such as brachial artery flow-mediated vasodilatation and plasma levels of endothelium-derived marker proteins. Up till now, there have been no controlled data on the effects of homocysteine-lowering treatment on vascular function or clinical end points. The precise mechanisms (if any) by which homocysteine mediates its adverse vascular effects are in fact unknown but may relate to impaired endothelial and smooth muscle cell function.