Toxicological assessment of e‐cigarette or vaping product use associated lung injury (EVALI) cartridges and constituents

Abstract

Rationale Definitive causative agents of the outbreak associated with the use of e-cigarette, or vaping product use associated lung injury (EVALI) are unknown. Patients diagnosed with EVALI have used vape products containing tetrahydrocannabinol (THC) and vitamin E acetate (VEA). Hypothesis We hypothesized that inhalation of these EVALI vape cartridges and their constituents induce pulmonary toxicity, mediated by oxidative damage and inflammatory responses, leading to acute lung injury, and alters SARS-CoV-2 related proteins. Methods Vaping products were recovered from hospitalized patients at the University of Rochester Medical Center. Cartridge constituents were characterized by gas chromatography and mass spectrometry. Comparative toxicity of exposure to common vape cartridge components such as medium-chain triglyceride (MCT) oil, VEA, and patient-derived cartridge aerosols was assessed by in vitro and in vivo models. Lung epithelial cells (BEAS-2B) and monocytes (Mono-Mac-6). Cells were exposed to MCT, VEA, and cartridge aerosols and the elicited inflammatory response, barrier function, and lipid-laden index were determined. C57BL/6 mice were exposed to MCT, VEA, and vape cartridge aerosols for three days (1 hr/day). The immune response was determined by differential cell counts, cytokine milieu, and lipidomics analysis in bronchoalveolar lavage fluid (BALF). Lung surfactant protein (SP-A), SARS-CoV-2 proteins (ACE2 and TMPRSS2) were quantified in the lung homogenates. Results Constituents identified patient-derived vaping products included reactive hydrocarbons and various forms of cannabinoids. VEA and cartridge aerosols induced significantly increased IL-6 and IL-8 responses in lung epithelial cells and monocytes. MCT, VEA, and cartridge aerosols induced barrier dysfunction. Increased lipid-laden indices were observed in MM6 cells. In mice, acute exposure to cartridge aerosols caused a significant infiltration of leukocytes in BALF and increased IL-6, eotaxin, and G-CSF in the BALF. Lipidomics analysis showed significantly increased eicosanoid inflammatory mediators and leukotrienes. Reduced levels of SP-A levels were seen in lung homogenates. Exposure to cartridge aerosols showed the most significant effects and toxicity compared to MCT and VEA. SARS-CoV-2 related proteins were not affected. Conclusion Acute exposure to vape cartridges induces cytotoxicity, barrier dysfunction, and elicit an inflammatory response in lung cells and mice, which are potential predictive toxicological markers of EVALI. Toxicity of vape cartridges was independent of SARS-CoV-2 proteins. This study provides important identification of potential chemical constituents, toxicological responses, and potential biomarkers of EVALI.