Electronic cigarette vapor disrupts key metabolic pathways in human lung epithelial cells

The steady increase in the use of electronic cigarettes (ECs) has reached an epidemic level, increasing mortality and morbidity, mainly due to pulmonary toxicity. Several mechanisms are involved in EC-induced toxicity, including oxidative stress and increased inflammation. Concurrently, the integrity of cellular metabolism is essential for cellular homeostasis and mitigation of toxic insults. However, the effects of EC on cellular metabolism remain largely unknown. In this study, we investigated the metabolic changes induced by EC in human lung epithelial cells (A549) using an untargeted metabolomics approach. A549 cells were exposed to increasing EC vapor extract concentrations, and cell viability, oxidative stress, and metabolomic changes were assessed. Our findings show that ECs induce cell death and increase oxidative stress in a concentration-dependent manner. Metabolomic studies demonstrated that ECs induce unique metabolic changes in key cellular metabolic pathways. Our results revealed that exposure to ECs induced clear segregation in metabolic responses which is driven significantly by number of essential metabolites such as aminoacids, fatty acids, glutathione, and pyruvate. Interstingly, our metabolomics results showed that each concentration of ECs induced unqiues pattern of metabolic changes, suggesting the complexity of ECs induced cytotoxcity. Disrupted metabolites were linked to essential cellular pathways, such as fatty acid biosynthesis, as well as glutathione, pyruvate, nicotinate and nicotinamide, and amino acid metabolisms. These results highlight the potential adverse effects of ECs on cellular metabolism and emphasize the need for further research to fully understand the long-term consequences of EC use. Overall, this study demonstrates that ECs not only induce cell death and oxidative stress but also disrupt cellular metabolism in A549 lung epithelial cells.