Summary
Introduction:
This text presents the results of a study examining the effects of electronic cigarette (EC) aerosol exposure on the cardiovascular system of adolescent mice. The study uses a mouse model of adolescent EC exposure and compares the results to mice exposed at adulthood and to hEPa-filtered air as a control. The study measures heart weight/tibia length ratio, echocardiography, pressure-volume loop recordings of the left ventricle, trichrome staining of cardiac tissue, ELISa targeting type I collagen, RT-qPCR, RNa-sequencing, and serum biomarkers using immunoassay.
Key Points:
* Exposure to EC aerosol with nicotine for 3 months reduced fractional shortening and impaired diastolic function in male mice, but not in female mice or in response to vehicle alone.
* Pressure-volume loop recordings revealed reduced contractility in male mice exposed to EC aerosol with and without nicotine.
* Trichrome staining of cardiac tissue revealed increased perivascular fibrosis in the male, adolescent vehicle group, relative to control and the nicotine group.
* RNa-sequencing showed that when comparing Fa with EC(+Nic), expression of many genes was altered in adolescent mice (71), and very few altered in adult mice (4).
* adolescent male mice exposed to EC aerosol had significantly elevated serum interleukin (IL)-18, chemokine C-C Motif Chemokine Ligand (CCL)2, macrophage inflammatory protein (MIP)-1 β, stem cell factor (SCF), and vascular endothelial growth factor (VEGF)-a.
* Nicotine concentrations in the serum of male and female mice exposed to EC with nicotine were similar, but concentrations of metabolites including cotinine and 3-hydroxycotinine were significantly lower in female mice.
* The 3hC/cotinine ratio, a measure of cytochrome P450 2a6 (Cyp2a5 in mice) activity, was significantly and substantially increased in female mice compared to male mice.
Main Message:
The study demonstrates that EC aerosol exposure can reduce cardiac function in developing male mice and promotes systemic inflammation which may cause further downstream changes to organ systems including the heart. The findings highlight the concern for the dangers of EC use, specifically in youth, and call for further work detailing the mechanistic contributions to the observed cardiac dysfunction. The study also suggests that females exhibit some degree of protection against EC aerosol from enhanced nicotine metabolism.
Citation
Neczypor EW, Saldaña Ta, Mears MJ, et al. e-Cigarette aerosol Reduces Left Ventricular Function in adolescent Mice. Circulation. 2022;145(11):868-870. doi:10.1161/CIRCULaTIONaha.121.057613
