Studies have shown that aerosols generated from flavored e-cigarettes contain Reactive Oxygen Species (ROS), promoting oxidative stress-induced damage within pulmonary cells. Our lab investigated the ROS content of e-cigarette vapor generated from disposable vape bars, a product exempt from the Federal Drug Enforcement Agency’s (FDA) 2020 flavor ban. Specifically, we analyzed vape bars belonging to multiple flavor categories (Tobacco, Minty Fruit, Fruity, Minty/Menthol, Desserts, and Drinks), manufactured by various vendors and of various nicotine concentrations (0-6.8%). Aerosols from these flavored vape bars were generated by a single puff aerosol generator and individually bubbled through a fluorogenic solution to detect and semi-quantify ROS in H2O2 equivalents generated by the vape bars. We compared and contrasted the ROS levels generated by each flavor as an indirect determinant of oxidative stress potential by these disposable vape bars. Our results showed that ROS concentration (μM) of aerosols produced from the vape bars varied significantly between different flavors and a function of nicotine concentration. Likewise, our results suggest that flavoring chemicals and nicotine concentration play a role in alerting ROS production in e-cigarette aerosols. Our study provides insight into the differential health effects of flavored disposable vape bars and the need for their regulation.

Cigarette smoke (CS) exposure results in lung damage and inflammation through mitochondrial dysfunction. Mitochondria quality control is sustained by Miro1 (Rhot1), a calcium-binding membrane-anchored GTPase by its interaction with PINK1/Parkin during mitophagy. However, the exact mechanism that operates this interaction of mitophagy machinery in Miro1 degradation and CS-induced mitochondrial dysfunction that results in lung inflammation remains unclear. We hypothesized that mitochondrial Miro1 plays an important role in regulating mitophagy machinery and resulting lung inflammation by CS in mouse lung. We showed a role of Miro1 in CS-induced mitochondrial dysfunction and quality control mechanisms. The Rhot1Fl/Fl (WT) and lung epithelial cell-specific Rhot1 KO were exposed to mainstream CS for 3 days (acute) and 4 months (chronic). The cellular infiltration, cytokines, and lung histopathology were studied for the inflammatory response in the lungs. Acute CS exposure showed a notable increase in the total inflammatory cells, macrophages, and neutrophils associated with inflammatory mediators and Miro1 associated mitochondrial quality control proteins Parkin and OPA1. Chronic exposure showed an increase infiltration of total inflammatory cells and neutrophils versus air controls. Histopathological changes, such as pulmonary macrophages and neutrophils were increased in CS exposed mice. The epithelial Miro1 ablation led to augmentation of inflammatory cell infiltration with alteration in the levels of pro-inflammatory cytokines and histopathological changes. Thus, CS induces disruption of mitochondrial quality control mechanisms, and Rhot1/Miro1 mediates the process of CS-induced mitochondrial dysfunction ensuing lung inflammatory responses.

Multi-walled carbon nanotubes are engineered nanomaterials (ENMs) that have a fiber-like structure which may be a concern for the development of cellular senescence. Premature senes-cence, a state of irreversible cell cycle arrest, is implicated in the pathogenesis of chronic lung dis-eases such as pulmonary fibrosis (PF). However, the crosstalk between downstream pathways mediating fibrotic and senescent responses of MWCNTs is not well defined. Here, we exposed human bronchial epithelial cells (BEAS2B) to MWCNTs for up to 72 hours and demonstrate that MWCNTs increase reactive oxygen species production (ROS) accompanied by inhibition of cell growth and proliferation. In addition, exposure resulted in the increase of p21 protein and senes-cence associated β-galactosidase (SA β-gal) activity. We also determined that co-exposure with the cytokine, transforming growth factor-β (TGF-β) exacerbated cellular senescence indicated by increased protein levels of p21, p16, and γH2A.X Furthermore, the production of fibronectin and plasminogen activator inhibitor (PAI-1) was significantly elevated with the co-exposure compared to MWCNTs or TGF-β alone. Together, this suggests that the senescence potential of MWCNTs may be enhanced by pro-fibrotic mediators in the surrounding microenvironment.