Hasan KM, et al. - In this study, researchers analyzed the harmful effects of electronic nicotine delivery systems (ENDS), also known as e-cigarettes, on the liver. For this investigation, apolipoprotein E null (ApoE-/-) mice on a Western diet (WD) were exposed to saline or ENDS with 2.4% nicotine aerosol for 12 weeks using a newly developed mouse ENDS exposure model system that delivers nicotine to mice that results in equivalent levels of serum cotinine found in humans. According to findings, ApoE-/- mice on a WD exposed to ENDS displayed a marked increase in hepatic lipid accumulation vs ApoE-/- on a similar diet exposed to saline aerosol. Functional analysis shows that in response to ENDS, genes associated with lipid metabolism, biosynthesis of cholesterol, and circadian rhythm were most significantly altered in the liver. These outcomes show profound adverse effects of ENDS on the liver. For regulatory agencies, this is important information as they regulate ENDS.