Key result
Exposure to higher doses of endothelium-derived extracellular vesicles impaired flow-induced dilation, while lower doses shifted the mediator of dilation from nitric oxide to hydrogen peroxide.
Endothelium-derived extracellular vesicles alter vascular function by impairing flow-induced dilation at high doses and shifting its mediator from NO to H2O2 at lower doses, requiring mitochondrial ROS for their formation.
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These in vitro results should not yet change practice; leaves open the in vivo impact of endothelium-derived EVs on vascular function.
To examine the effect of endothelium-derived extracellular vesicles (eEVs) on the mediator of flow-induced dilation (FID), composition, formation, and functional effects on the mediator of FID were examined from two different eEV subtypes, one produced from ceramide, while the other was produced from plasminogen-activator inhibitor 1 (PAI-1). Using video microscopy, we measured internal-diameter changes in response to increases in flow in human adipose resistance arteries acutely exposed (30 min) to eEVs derived from cultured endothelial cells exposed to ceramide or PAI-1. FID was significantly impaired following exposure to 500K/ml (K = 1,000) of ceramide-induced eEVs (Cer-eEVs) but unaffected by 250K/ml. FID was reduced in the presence of PEG-catalase following administration of 250K/ml of Cer-eEVs and PAI-1 eEVs, whereas Nω-nitro-l-arginine methyl ester (l-NAME) had no effect. Pathway analysis following protein composition examination using liquid chromatography tandem mass spectrometry (LC-MS/MS) demonstrated that both subtypes were strongly linked to similar biological functions, primarily, mitochondrial dysfunction. Flow cytometry was used to quantify eEVs in the presence or absence of l-phenylalanine-4′-boronic acid (PBA) and mitochondria-targeted [93-boronophenyl)methyl]triphenyl-phosphonium (mito-PBA), cytosolic and mitochondrial-targeted antioxidants, respectively. eEV formation was significantly and dramatically reduced with mito-PBA treatment. In conclusion, eEVs have a biphasic effect, with higher doses impairing and lower doses shifting the mediator of FID from nitric oxide (NO) to hydrogen peroxide (H2O2). Despite differences in protein content, eEVs may alter vascular function in similar directions, regardless of the stimulus used for their formation. Furthermore, mitochondrial ROS production is required for the generation of these vesicles. NEW & NOTEWORTHY The vascular effect of endothelium-derived extracellular vesicles (eEVs) is biphasic, with higher doses decreasing the magnitude of flow-induced dilation (FID) compared with lower doses that shift the mediator of FID from nitric oxide to H2O2. eEVs may cause vascular dysfunction via similar pathways despite being formed from different stimuli, although both require mitochondrial reactive oxygen species for their formation.
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Freed et al. (2017) studied this question. Endothelium-derived extracellular vesicles (eEVs) was evaluated on Flow-induced dilation (FID). Exposure to higher doses of endothelium-derived extracellular vesicles impaired flow-induced dilation, while lower doses shifted the mediator of dilation from nitric oxide to hydrogen peroxide.
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