Immunolocalization of high-density lipoproteins in arterial walls of rats
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Published on: December 7, 2013
1Department of Biology, Tunghai University, Taichung, Taiwan, ROC. vcyang@mail.thu.edu.tw
Insights
High-density lipoprotein (HDL) distributes within arterial walls, particularly in endothelial and smooth muscle cells. Dietary cholesterol influences HDL accumulation in these cells and the arterial extracellular matrix.
Area of Science:
- Cardiovascular Biology
- Lipoprotein Metabolism
- Atherosclerosis Research
Background:
- Serum high-density lipoprotein (HDL) levels inversely correlate with coronary heart disease, suggesting a protective role.
- Limited data exists on HDL distribution within the arterial wall.
- Understanding HDL's localization is crucial for elucidating its anti-atherosclerotic mechanisms.
Purpose of the Study:
- To investigate the distribution of HDL across the arterial wall.
- To quantify HDL's presence in different arterial compartments under varying dietary conditions.
Main Methods:
- Immunogold labeling of ultrathin rat arterial tissue sections.
- Electron microscopic examination for HDL localization.
- Quantitative analysis of HDL labeling in cellular and extracellular compartments.
Main Results:
- HDL was detected in endothelial cell cytoplasm, smooth muscle cell cytoplasm, subendothelial space, extracellular matrix, and intercellular clefts.
- Rats on a high-cholesterol diet showed increased HDL labeling in the subendothelial space, smooth muscle cells, and extracellular matrix compared to controls.
- Prolonged high-cholesterol diet significantly increased intracellular HDL in endothelial and smooth muscle cells.
Conclusions:
- HDL resides within multiple compartments of the arterial wall, including intracellular spaces.
- Dietary cholesterol significantly impacts HDL accumulation within the arterial wall.
- These findings provide insights into HDL's role in arterial health and atherosclerosis development.
Abstract:
The inverse correlation between serum high-density lipoprotein (HDL) levels and coronary heart disease in humans suggests that HDL has a protective effect against the development of atherosclerosis. However, there is a lack of data concerning its distribution across the arterial wall. In order to detect this lipoprotein, we performed immunogold labeling on ultrathin sections of L.R. White embedded rat arterial tissue. Electron microscopic examination revealed that HDL was localized in the cytoplasm of the endothelial cells and the smooth muscle cells, but not in the nucleus or other organelles. The HDL was also present in the subendothelial space, the extracellular matrix as well as the intercellular clefts between the endothelial cells. Quantitative study revealed that rats on a high cholesterol diet for one month have more immunogold labeling (P < 0.05) in the subendothelial space, the smooth muscle cells and the extracellular matrix as compared to rats on a normal diet. After 12 months of normal diet, the intracellular labeling was significantly increased (P < 0.05) in the endothelial cells and the smooth muscle cells as compared to 1 month on the normal diet. The increase was greater (P < 0.05) for the high-cholesterol diet than for the normal diet treatment.
