Aerosolized vitamin E acetate causes oxidative injury in mice and in alveolar macrophages

Comparison of emissions across tobacco products: A slippery slope in tobacco control

In this narrative review, we highlight the challenges of comparing emissions from different tobacco products under controlled laboratory settings (using smoking/vaping machines). We focus on tobacco products that generate inhalable smoke or aerosol, such as cigarettes, cigars, hookah, electronic cigarettes, and heated tobacco products. We discuss challenges associated with sample generation including variability of smoking/vaping machines, lack of standardized adaptors that connect smoking/vaping machines to different tobacco products, puffing protocols that are not representative of actual use, and sample generation session length (minutes or number of puffs) that depends on product characteristics. We also discuss the challenges of physically characterizing and trapping emissions from products with different aerosol characteristics. Challenges to analytical method development are also covered, highlighting matrix effects, order of magnitude differences in analyte levels, and the necessity of tailored quality control/quality assurance measures. The review highlights two approaches in selecting emissions to monitor across products, one focusing on toxicants that were detected and quantified with optimized methods for combustible cigarettes, and the other looking for product-specific toxicants using non-targeted analysis. The challenges of data reporting and statistical analysis that allow meaningful comparison across products are also discussed. We end the review by highlighting that even if the technical challenges are overcome, emission comparison may obscure the absolute exposure from novel products if we only focus on relative exposure compared to combustible products.

Lipid from electronic cigarette-aerosol both with and without nicotine induced pro-inflammatory macrophage polarization and disrupted phagocytosis

Clinical cases and experimental evidence revealed that electronic cigarettes (ECIG) induce serious adverse health effects, but underlying mechanisms remain to be fully uncovered. Based on recent exploratory evidence, investigating the effects of ECIG on macrophages can broadly define potential mechanisms by focusing on the effect of ECIG exposure with or without nicotine. Here we investigated the effect of ECIG-aerosol exposure on macrophages (MQ) phenotype, inflammatory response, and function of macrophages.MQ were cultured at air liquid interface and exposed to ECIG-aerosol. Oxidative stress was determined by reactive oxygen species (ROS), heat shock protein 60 (HSP60), glutathione peroxidase (GPx) and heme oxygenase1 (HMOX1). Lipid accumulation and lipid peroxidation were defined by lipid staining and level of malondialdehyde (MDA) respectively. MQ polarization was identified by surface expression markers CD86, CD11C and CD206 as well as pro-inflammatory and anti-inflammatory cytokines in gene and protein level. Phagocytosis of E. coli by MQ was investigated by fluorescence-based phagocytosis assay.ECIG-aerosol exposure in presence or absence of nicotine induced oxidative stress evidenced by ROS, HSP60, GPx, GPx4 and HMOX1 upregulation in MQ. ECIG-aerosol exposure induced accumulation of lipids and the lipid peroxidation product MDA in MQ. Pro-inflammatory MQ (M1) markers CD86 and CD11C but not anti-inflammatory MQ (M2) marker CD206 were upregulated in response to ECIG-aerosol exposure. In addition, ECIG induced pro-inflammatory cytokines IL-1beta and IL-8 in gene level and IL-6, IL-8, and IL-1beta in protein level whereas ECIG exposure downregulated anti-inflammatory cytokine IL-10 in protein level. Phagocytosis activity of MQ was downregulated by ECIG exposure. shRNA mediated lipid scavenger receptor 'CD36' silencing inhibited ECIG-aerosol-induced pro-inflammatory MQ polarization and recovered phagocytic activity of MQ.ECIG exposure alters lung lipid homeostasis and thus induced inflammation by inducing M1 type MQ and impair phagocytic function, which could be a potential cause of ECIG-induced lung inflammation in healthy and inflammatory exacerbation in disease condition.

Multi-omic assessment shows dysregulation of pulmonary and systemic immunity to e-cigarette exposure

Electronic cigarette (Ecig) use has become more common, gaining increasing acceptance as a safer alternative to tobacco smoking. However, the 2019 outbreak of Ecig and Vaping-Associated Lung Injury (EVALI) alerted the community to the potential for incorporation of deleterious ingredients such as vitamin E acetate into products without adequate safety testing. Understanding Ecig induced molecular changes in the lung and systemically can provide a path to safety assessment and protect consumers from unsafe formulations. While vitamin E acetate has been largely removed from commercial and illicit products, many Ecig products contain additives that remain largely uncharacterized. In this study, we determined the lung-specific effects as well as systemic immune effects in response to exposure to a common Ecig base, propylene glycol and vegetable glycerin (PGVG), with and without a 1% addition of phytol, a diterpene alcohol that has been found in commercial products. We exposed animals to PGVG with and without phytol and assessed metabolite, lipid, and transcriptional markers in the lung. We found both lung-specific as well as systemic effects in immune parameters, metabolites, and lipids. Phytol drove modest changes in lung function and increased splenic CD4 T cell populations. We also conducted multi-omic data integration to better understand early complex pulmonary responses, highlighting a central enhancement of acetylcholine responses and downregulation of palmitic acid connected with conventional flow cytometric assessments of lung, systemic inflammation, and pulmonary function. Our results demonstrate that Ecig exposure not only leads to changes in pulmonary function but also affects systemic immune and metabolic parameters.

Aerosolized nicotine from e-cigarettes alters gene expression, increases lung protein permeability, and impairs viral clearance in murine influenza infection

E-cigarette use has rapidly increased as an alternative means of nicotine delivery by heated aerosolization. Recent studies demonstrate nicotine-containing e-cigarette aerosols can have immunosuppressive and pro-inflammatory effects, but it remains unclear how e-cigarettes and the constituents of e-liquids may impact acute lung injury and the development of acute respiratory distress syndrome caused by viral pneumonia. Therefore, in these studies, mice were exposed one hour per day over nine consecutive days to aerosol generated by the clinically-relevant tank-style Aspire Nautilus aerosolizing e-liquid containing a mixture of vegetable glycerin and propylene glycol (VG/PG) with or without nicotine. Exposure to the nicotine-containing aerosol resulted in clinically-relevant levels of plasma cotinine, a nicotine-derived metabolite, and an increase in the pro-inflammatory cytokines IL-17A, CXCL1, and MCP-1 in the distal airspaces. Following the e-cigarette exposure, mice were intranasally inoculated with influenza A virus (H1N1 PR8 strain). Exposure to aerosols generated from VG/PG with and without nicotine caused greater influenza-induced production in the distal airspaces of the pro-inflammatory cytokines IFN-γ, TNFα, IL-1β, IL-6, IL-17A, and MCP-1 at 7 days post inoculation (dpi). Compared to the aerosolized carrier VG/PG, in mice exposed to aerosolized nicotine there was a significantly lower amount of Mucin 5 subtype AC (MUC5AC) in the distal airspaces and significantly higher lung permeability to protein and viral load in lungs at 7 dpi with influenza. Additionally, nicotine caused relative downregulation of genes associated with ciliary function and fluid clearance and an increased expression of pro-inflammatory pathways at 7 dpi. These results show that (1) the e-liquid carrier VG/PG increases the pro-inflammatory immune responses to viral pneumonia and that (2) nicotine in an e-cigarette aerosol alters the transcriptomic response to pathogens, blunts host defense mechanisms, increases lung barrier permeability, and reduces viral clearance during influenza infection. In conclusion, acute exposure to aerosolized nicotine can impair clearance of viral infection and exacerbate lung injury, findings that have implications for the regulation of e-cigarette products.

External Factors Modulating Vaping-Induced Thermal Degradation of Vitamin E Acetate

Despite previous studies indicating the thermal stability of vitamin E acetate (VEA) at low temperatures, VEA has been shown to readily decompose into various degradation products such as alkenes, long-chain alcohols, and carbonyls such as duroquinone (DQ) at vaping temperatures of <200 °C. While most models simulate the thermal decomposition of e-liquids under pyrolysis conditions, numerous factors, including vaping behavior, device construction, and the surrounding environment, may impact the thermal degradation process. In this study, we investigated the role of the presence of molecular oxygen (O2) and transition metals in promoting thermal oxidation of e-liquids, resulting in greater degradation than predicted by pure pyrolysis. Thermal degradation of VEA was performed in inert (N2) and oxidizing atmospheres (clean air) in the absence and presence of Ni-Cr and Cu-Ni alloy nanopowders, metals commonly found in the heating coil and body of e-cigarettes. VEA degradation was analyzed using thermogravimetric analysis (TGA) and gas chromatography/mass spectrometry (GC/MS). While the presence of O2 was found to significantly enhance the degradation of VEA at both high (356 °C) and low (176 °C) temperatures, the addition of Cu-Ni to oxidizing atmospheres was found to greatly enhance VEA degradation, resulting in the formation of numerous degradation products previously identified in VEA vaping emissions. O2 and Cu-Ni nanopowder together were also found to significantly increase the production of OH radicals, which has implications for e-liquid degradation pathways as well as the potential risk of oxidative damage to biological systems in real-world vaping scenarios. Ultimately, the results presented in this study highlight the importance of oxidation pathways in VEA thermal degradation and may aid in the prediction of thermal degradation products from e-liquids.

The implications of Vitamin E acetate in E-cigarette, or vaping, product use-associated lung injury

In the summer of 2019, a cluster of cases were observed with users of battery-operated or superheating devices presenting with multiple symptoms, such as dyspnea, cough, fever, constitutional symptoms, gastrointestinal upset, and hemoptysis, that is now termed e-cigarette, or vaping, product use-associated lung injury (EVALI). The Centers for Disease Control and Prevention reported 2807 cases within the USA leading to at least 68 deaths as of February 18, 2020. The heterogeneous presentations of EVALI make diagnosis and treatment difficult; however, treatment focused on identifying and removal of the noxious substance and providing supportive care. Vitamin E acetate (VEA) is a likely cause of this lung injury, and others have reported other components to play a possible role, such as nicotine and vegetable glycerin/propylene glycol. EVALI is usually observed in adolescents, with a history of vaping product usage within 90 days typically containing tetrahydrocannabinol, and presenting on chest radiograph with pulmonary infiltrates or computed tomography scan with ground-glass opacities. Diagnosis requires a high degree of suspicion to diagnose and exclusion of other possible causes of lung disease. Here, we review the current literature to detail the major factors contributing to EVALI and primarily discuss the potential role of VEA in EVALI. We will also briefly discuss other constituents other than just VEA, as a small number of EVALI cases are reported without the detection of VEA, but with the same clinical diagnosis.

E-cigarette vaping associated acute lung injury (EVALI): state of science and future research needs

"E-Cigarette (e-cig) Vaping-Associated Acute Lung Injury" (EVALI) has been linked to vitamin-E-acetate (VEA) and Δ-9-tetrahydrocannabinol (THC), due to their presence in patients' e-cigs and biological samples. Lacking standardized methodologies for patients' data collection and comprehensive physicochemical/toxicological studies using real-world-vapor exposures, very little data are available, thus the underlying pathophysiological mechanism of EVALI is still unknown. This review aims to provide a comprehensive and critical appraisal of existing literature on clinical/epidemiological features and physicochemical-toxicological characterization of vaping emissions associated with EVALI. The literature review of 161 medical case reports revealed that the predominant demographic pattern was healthy white male, adolescent, or young adult, vaping illicit/informal THC-containing e-cigs. The main histopathologic pattern consisted of diffuse alveolar damage with bilateral ground-glass-opacities at chest radiograph/CT, and increased number of macrophages or neutrophils and foamy-macrophages in the bronchoalveolar lavage. The chemical analysis of THC/VEA e-cig vapors showed a chemical difference between THC/VEA and the single THC or VEA. The chemical characterization of vapors from counterfeit THC-based e-cigs or in-house-prepared e-liquids using either cannabidiol (CBD), VEA, or medium-chain triglycerides (MCT), identified many toxicants, such as carbonyls, volatile organic compounds, terpenes, silicon compounds, hydrocarbons, heavy metals, pesticides and various industrial/manufacturing/automotive-related chemicals. There is very scarce published toxicological data on emissions from THC/VEA e-liquids. However, CBD, MCT, and VEA emissions exert varying degrees of cytotoxicity, inflammation, and lung damage, depending on puffing topography and cell line. Major knowledge gaps were identified, including the need for more systematic-standardized epidemiological surveys, comprehensive physicochemical characterization of real-world e-cig emissions, and mechanistic studies linking emission properties to specific toxicological outcomes.