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Macrophage Foam Cell – Derived Extracellular Vesicles Promote Vascular Smooth Muscle Cell Migration and Adhesion

View Article: PubMed Central - PubMed

ABSTRACT

Background: A new mechanism for intercellular communication has recently emerged that involves intercellular transfer of extracellular vesicles (EVs). Several studies have indicated that EVs may play a potential role in cell‐to‐cell communication between macrophage foam cells and vascular smooth muscle cells (VSMCs) in atherosclerotic lesion.

Methods and results: This study involved the comparison of circulating EVs from atherosclerotic patients and control participants. The results showed that the circulation of the patients contained more leukocyte‐derived EVs and that these EVs promoted more VSMC adhesion and migration than those of healthy participants. We then established a macrophage foam cell model and characterized the EVs from the macrophages. We used flow cytometric analyses and cell migration and adhesion assays and determined that the foam cells generated more EVs than the normal macrophages and that the foam cell–derived EVs were capable of promoting increased levels of VSMC migration and adhesion. Furthermore, we performed a proteomic analysis of the EVs. The data showed that the foam cell–derived EVs may promote VSMC adhesion and migration by regulating the actin cytoskeleton and focal adhesion pathways. In addition, Western blotting revealed that foam cell–derived EVs could promote the phosphorylation of ERK and Akt in VSMCs in a time‐dependent manner. We also found that foam cell–derived EVs could enter the VSMCs and transfer integrins to the surface of these cells.

Conclusions: The data in our present study provide the first evidence that EVs from foam cells could promote VSMC migration and adhesion, which may be mediated by the integration of EVs into VSMCs and the subsequent downstream activation of ERK and Akt.

No MeSH data available.


Related in: MedlinePlus

FC‐EVs activate the ERK and Akt pathways. A, A representative Western blot result of the phosphorylated forms of ERK and Akt and the total ERK and Akt from VSMCs that had been treated with FC‐EVs for the indicated time. B, The line graph of the results of the Western blot. The phosphorylation level was calculated as the ratio of the integrated optical density value of the phosphorylated protein to that of corresponding total protein. C and D, The results of the Western blot for VSMCs treated with the normal macrophage–derived EVs. FC‐EVs indicates foam cell–derived extracellular vesicles; P, phosphorylated; T, total; VSMC, vascular smooth muscle cell.
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jah31829-fig-0005: FC‐EVs activate the ERK and Akt pathways. A, A representative Western blot result of the phosphorylated forms of ERK and Akt and the total ERK and Akt from VSMCs that had been treated with FC‐EVs for the indicated time. B, The line graph of the results of the Western blot. The phosphorylation level was calculated as the ratio of the integrated optical density value of the phosphorylated protein to that of corresponding total protein. C and D, The results of the Western blot for VSMCs treated with the normal macrophage–derived EVs. FC‐EVs indicates foam cell–derived extracellular vesicles; P, phosphorylated; T, total; VSMC, vascular smooth muscle cell.

Mentions: The reported data indicated that FC‐EVs contained numerous proteins that are involved in cell migration and adhesion pathways and that these EVs could promote VSMC migration and adhesion. It is well known that some key downstream signaling molecules, including ERK and Akt, are involved in cell migration and adhesion. Consequently, the phosphorylation levels of these molecules may change during FC‐EV–induced promotion of VSMC migration and adhesion. To evaluate this possibility, we treated 80%‐confluent VSMCs with 20 μg/mL of FC‐EVs and then determined the total and phosphorylated levels of ERK and Akt in the cells using Western blotting. As expected, treatment with EVs resulted in time‐dependent increases in the phosphorylation of ERK and Akt in VSMCs. At 4 hours, when the highest level of activation was observed, the phosphorylation of these proteins was increased by 47.0% and 55.7%, respectively (Figure 5A and 5B); however, the NM‐EVs had no effect on these pathways (Figure 5C and 5D).


Macrophage Foam Cell – Derived Extracellular Vesicles Promote Vascular Smooth Muscle Cell Migration and Adhesion
FC‐EVs activate the ERK and Akt pathways. A, A representative Western blot result of the phosphorylated forms of ERK and Akt and the total ERK and Akt from VSMCs that had been treated with FC‐EVs for the indicated time. B, The line graph of the results of the Western blot. The phosphorylation level was calculated as the ratio of the integrated optical density value of the phosphorylated protein to that of corresponding total protein. C and D, The results of the Western blot for VSMCs treated with the normal macrophage–derived EVs. FC‐EVs indicates foam cell–derived extracellular vesicles; P, phosphorylated; T, total; VSMC, vascular smooth muscle cell.
© Copyright Policy - creativeCommonsBy-nc
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121506&req=5

jah31829-fig-0005: FC‐EVs activate the ERK and Akt pathways. A, A representative Western blot result of the phosphorylated forms of ERK and Akt and the total ERK and Akt from VSMCs that had been treated with FC‐EVs for the indicated time. B, The line graph of the results of the Western blot. The phosphorylation level was calculated as the ratio of the integrated optical density value of the phosphorylated protein to that of corresponding total protein. C and D, The results of the Western blot for VSMCs treated with the normal macrophage–derived EVs. FC‐EVs indicates foam cell–derived extracellular vesicles; P, phosphorylated; T, total; VSMC, vascular smooth muscle cell.
Mentions: The reported data indicated that FC‐EVs contained numerous proteins that are involved in cell migration and adhesion pathways and that these EVs could promote VSMC migration and adhesion. It is well known that some key downstream signaling molecules, including ERK and Akt, are involved in cell migration and adhesion. Consequently, the phosphorylation levels of these molecules may change during FC‐EV–induced promotion of VSMC migration and adhesion. To evaluate this possibility, we treated 80%‐confluent VSMCs with 20 μg/mL of FC‐EVs and then determined the total and phosphorylated levels of ERK and Akt in the cells using Western blotting. As expected, treatment with EVs resulted in time‐dependent increases in the phosphorylation of ERK and Akt in VSMCs. At 4 hours, when the highest level of activation was observed, the phosphorylation of these proteins was increased by 47.0% and 55.7%, respectively (Figure 5A and 5B); however, the NM‐EVs had no effect on these pathways (Figure 5C and 5D).

View Article: PubMed Central - PubMed

ABSTRACT

Background: A new mechanism for intercellular communication has recently emerged that involves intercellular transfer of extracellular vesicles (EVs). Several studies have indicated that EVs may play a potential role in cell‐to‐cell communication between macrophage foam cells and vascular smooth muscle cells (VSMCs) in atherosclerotic lesion.

Methods and results: This study involved the comparison of circulating EVs from atherosclerotic patients and control participants. The results showed that the circulation of the patients contained more leukocyte‐derived EVs and that these EVs promoted more VSMC adhesion and migration than those of healthy participants. We then established a macrophage foam cell model and characterized the EVs from the macrophages. We used flow cytometric analyses and cell migration and adhesion assays and determined that the foam cells generated more EVs than the normal macrophages and that the foam cell–derived EVs were capable of promoting increased levels of VSMC migration and adhesion. Furthermore, we performed a proteomic analysis of the EVs. The data showed that the foam cell–derived EVs may promote VSMC adhesion and migration by regulating the actin cytoskeleton and focal adhesion pathways. In addition, Western blotting revealed that foam cell–derived EVs could promote the phosphorylation of ERK and Akt in VSMCs in a time‐dependent manner. We also found that foam cell–derived EVs could enter the VSMCs and transfer integrins to the surface of these cells.

Conclusions: The data in our present study provide the first evidence that EVs from foam cells could promote VSMC migration and adhesion, which may be mediated by the integration of EVs into VSMCs and the subsequent downstream activation of ERK and Akt.

No MeSH data available.


Related in: MedlinePlus