Hasan KM, et al. - In this investigation, researchers studied the harmful effects of electronic nicotine delivery systems (ENDS), also known as e-cigarettes, on the liver. 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. The investigators observed that ApoE-/- mice on a WD exposed to ENDS showed a marked increase in hepatic lipid accumulation vs ApoE-/- on a similar diet exposed to saline aerosol. Functional analysis shows that genes associated with lipid metabolism, cholesterol biosynthesis, and circadian rhythm have been altered most significantly in the liver in response to ENDS. These outcomes exhibit profound adverse effects of ENDS on the liver. This information is important for the regulatory agencies that regulate ENDS.