Abstract
Aims:
Nicotine, a major component of tobacco, is an important factor contributing to atherosclerosis. However, the molecular mechanisms underlying the link between nicotine and atherosclerosis are unclear. As extracellular vesicles (EVs) are involved in intercellular communication in atherosclerosis, we investigated whether their influence on arterial pathophysiology under nicotine stimulation.
Methods:
and results: EVs from the serum of smokers (smoker-EVs) were significantly increased and exacerbated endothelial inflammation as well as apoptosis according to functional studies. Meanwhile, inhibition of EVs blunted the nicotine-induced atherosclerosis progression, and injection of nicotine-induced EVs promoted atherosclerosis progression in ApoE-/- mice. Furthermore, quantitative reverse transcription-polymerase chain reaction analysis revealed a remarkable increase in miR-155 levels in smoker-EVs, which was correlated with carotid plaque formation in patients measured by ultrasound imaging. Moreover, CD14 levels were significantly increased in EVs from smokers (representing EVs derived from monocytes), indicating that monocytes are an important source of smoker-EVs. DNA methylation and the transcription factor HIF1α may contribute to increased miR-155 levels in monocytes, as assessed with bisulfite conversion sequencing and chromatin immunoprecipitation. Mechanistically, EVs encapsulated miR-155 induced endothelial cell dysfunction by directedly targeting BCL2, MCL1, TIMP3, BCL6 and activating NF-κB pathway, as verified in a series of molecular and biological experiments. Injecting EVs from nicotine-stimulated monocytes promoted plaque formation and triggered vascular endothelial injury in ApoE-/- mice, whereas inhibition of miR-155 weakened this effect.
Conclusion:
Our findings revealed an EV-dependent mechanism of nicotine-aggravated atherosclerosis. Accordingly, we propose an EV-based intervention strategy for atherosclerosis management.
Translational perspective:
Based on the findings of our study, strategies preventing or blocking the production of abnormal EVs, particularly monocyte EVs, after nicotine stimulation may protect against atherosclerosis. Moreover, detection of circulating EVs-carried miR-155 expression may reveal the progression of atherosclerosis. On the molecular level, blocking miR-155 biogenesis, which constituted a novel therapeutic approach, may protect against nicotine aggravating atherosclerosis.
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