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Erythrocytophagocytosis by arterial smooth muscle cells in experimental atherosclerosis
Insights
Arterial smooth muscle cells in pigs with atherosclerosis exhibit phagocytosis of erythrocytes, acting as macrophages. This process is linked to plaque vascularization and vessel wall injury.
Area of Science:
- Cardiovascular Pathology
- Vascular Biology
- Cellular Biology
Background:
- Advanced atherosclerosis, induced by an atherogenic diet in pigs, presents with plaque hemorrhage and vascularization in coronary arteries and the abdominal aorta.
- Erythrophagocytosis (phagocytosis of erythrocytes) is observed within these atherosclerotic plaques.
Purpose of the Study:
- To investigate the cellular mechanisms underlying phagocytosis in advanced atherosclerotic plaques.
- To identify the cell types involved in erythrocyte phagocytosis within injured arterial walls.
Main Methods:
- Morphological examination of atherosclerotic lesions in pig coronary arteries and abdominal aorta.
- Detailed ultrastructural analysis of cells involved in phagocytosis.
Main Results:
- Cells exhibiting phagocytosis share common features with arterial smooth muscle cells, including basement membrane components, caveolae, and myofilaments.
- Smooth muscle cell modulation is observed, progressing with the phagocytic process.
- These cells display characteristics suggesting adaptation as macrophages with lysosomal enzymes.
Conclusions:
- Arterial smooth muscle cells can participate in phagocytic processes within injured vessel walls under specific conditions, potentially acting as macrophages.
- Vascularization of arterial plaques appears related to these phagocytic activities.
- Extracellular environment and vessel wall conditions are crucial in inducing phagocytosis by smooth muscle cells.
Abstract:
The morphological examination of advanced atherosclerosis caused by atherogenic diet in the coronary arteries and in the aorta abdominalis (trifurcation) of pigs showed plaque hemorrhage and signs of vascularisation. In these areas phagocytosis of erythrocytes could be observed. The cells involved in the phagocytic process vary considerably in size and shape but show common features of arterial smooth muscle cells. The modulation of smooth muscle cells is evident and progresses as the process of phagocytosis progresses. In early stages of erythrocyte engulfment the morphological characteristics which identify these cells as of smooth muscle origin are parts of surrounding basement membrane, caveolae intracellulares and myofilaments. The authors suggest, that under certain conditions arterial smooth muscle cells participate in phagocytic processes in the injured vessel wall as potential macrophages with lysosomal enzyme adaptation. Changes in extracellular surroundings and the actual situation of the vessel wall condition seem to play an important role in the induction of phagocytosis. Relations to vascularisation processes of the arterial plaques are evident.