Effects of chronic vapor inhalation on mouse body weight, lung morphology, and inflammatory cytokines using a low vapor exposure design

Electronic-cigarette (ECIG) use increased over the last decade as many find vaping as a safe alternative to cigarettes; however, the safety of ECIGs on biological functions are still not fully understood. The present study evaluated the effects of daily ECIG use on body weight, lung tissue, and inflammatory cytokines using a low vapor exposure design as many teenagers use ECIGs sporadically throughout the day rather than heavy consistent use found in the adult population. Mice were divided evenly into three groups: Control (no vapor treatment), vapor vehicle (nicotine-free vapor), and 30.0 mg/mL nicotine. Mice received two vapor inhalation sessions per day for 28 days in which mice received a 3-s vapor puff every 2 min for 10 min (6 puffs total). On day 29, mice were sacrificed after a final vapor administration session, and lungs were examined microscopically with hematoxylin & eosin stain and ten inflammatory cytokines were assessed. Mice in the vape groups failed to gain weight over the 28 days. Control mice significantly increased weight in a linear fashion. Deleterious lung morphologies were significantly higher in the vape groups as compared to controls (12 vs 3) with all of the vapor mice showing at least one deleterious lung morphology. IL-2 and IL-6 were significantly decreased in vape mice. This study found that vapor inhalation significantly hindered weight gain and damaged lungs of both nicotine and vehicle groups, suggesting that damage may be caused by vapor inhalation, rather than nicotine.