E-cigarette Aerosol Research Articles

Exploring the Utility of Long Non-Coding RNAs for Assessing the Health Consequences of Vaping.

Electronic cigarette (e-cig) use, otherwise known as "vaping", is widespread among adolescent never-smokers and adult smokers seeking a less-harmful alternative to combustible tobacco products. To date, however, the long-term health consequences of vaping are largely unknown. Many toxicants and carcinogens present in e-cig vapor and tobacco smoke exert their biological effects through epigenetic changes that can cause dysregulation of disease-related genes. Long non-coding RNAs (lncRNAs) have emerged as prime regulators of gene expression in health and disease states. A large body of research has shown that lncRNAs regulate genes involved in the pathogenesis of smoking-associated diseases; however, the utility of lncRNAs for assessing the disease-causing potential of vaping remains to be fully determined. A limited but growing number of studies has shown that lncRNAs mediate dysregulation of disease-related genes in cells and tissues of vapers as well as cells treated in vitro with e-cig aerosol extract. This review article provides an overview of the evolution of e-cig technology, trends in use, and controversies on the safety, efficacy, and health risks or potential benefits of vaping relative to smoking. While highlighting the importance of lncRNAs in cell biology and disease, it summarizes the current and ongoing research on the modulatory effects of lncRNAs on gene regulation and disease pathogenesis in e-cig users and in vitro experimental settings. The gaps in knowledge are identified, priorities for future research are highlighted, and the importance of empirical data for tobacco products regulation and public health is underscored.

Method Development and Validation of an Aerosol Sampling Technique for the Analysis of Nicotine in Electronic Cigarette Aerosols.

Because of the increasing popularity of e-cigarettes, monitoring the e-cigarette market has become important for national health authorities to guarantee safety and quality. In the EU, the Tobacco Products Directive requires emission studies for e-cigarette products. The absence of industry guidelines for studying these emissions and the lack of proper validation in the literature led us to develop and validate a method using the total error approach for the determination of nicotine in e-cigarette aerosols. A commercial vaping device was used to generate aerosols, which were then collected on Cambridge filter pads and measured for nicotine concentration by UHPLC-DAD after extraction. The method was successfully validated by generating accuracy profiles, which show that the β-expectation tolerance intervals remained below the acceptance limits of ±20%. Within-run repeatability and intermediate precision were considered acceptable since the highest RSD value obtained was below 5%. The method was applied to 15 commercial e-liquids. A complete validation of a method for the analysis of e-cigarette emissions is presented, including several parameters that impact the accuracy and reproducibility. Similar systematic approaches for method development and validation could be used for other e-cigarette emission analysis methods to ensure the reliability of the measurements.

Chronic Exposure to Both Electronic and Conventional Cigarettes Alters Ileum and Colon Turnover, Immune Function, and Barrier Integrity in Mice.

Although the effects of cigarette smoke (CS) on the development of several intestinal diseases is well documented, the impact of e-cigarette aerosol (e-cig) on digestive health is largely unknown. To compare the effects of e-cig and CS on mouse ileum and colon, animals were chronically exposed for 6 months by nose-only inhalation to e-cig at 18 or 30 W power, or to 3R4F CS. Results showed that e-cig exposure decreased colon cell proliferation. Several other proliferative defects were observed in response to both e-cig and CS exposure, including up- and down-regulation of cyclin D1 protein levels in the ileum and colon, respectively. E-cig and CS exposure reduced myeloperoxidase activity in the ileum. In the colon, both exposures disrupted gene expression of cytokines and T cell transcription factors. For tight junction genes, ZO-1- and occludin-protein expression levels were reduced in the ileum and colon, respectively, by e-cig and CS exposure. The 16S sequencing of microbiota showed specific mild dysbiosis, according to the type of exposure. Overall, e-cig exposure led to altered proliferation, inflammation, and barrier function in both the ileum and colon, and therefore may be a gut hazard on par with conventional CS.

Examining the Oxidation States of Metals in Aerosols Emitted by Electronic Cigarettes.

Electronic cigarettes (ECs) emit many toxic substances, including metals, that can pose a threat to users and the environment. The toxicity of the emitted metals depends on their oxidation states. Hence, this study examines the oxidation states of metals observed in EC aerosols. X-ray photoelectron spectroscopy analysis of the filters that collected EC aerosols identified the oxidation states of five primary metals (based on surface sample analysis), including chromium(III) (close to 100%) under low power setting while a noticeable amount of chromium(VI) (15%) at higher power settings of the EC, and copper(II) (100%), zinc(II) (100%), nickel(II) (100%), lead(II) (65%), and lead(IV) (35%) regardless of power settings. This observation indicates that the increased temperature due to higher power settings could alter the oxidation states of certain metals. We noted that many metals were in their lesser toxic states; however, inhaling these metals may still pose health risks.

Secondhand Nicotine Absorption From E-Cigarette Vapor vs Tobacco Smoke in Children

ImportanceWith the prevalence of e-cigarette use (vaping) increasing worldwide, there are concerns about children’s exposure to secondhand vapor.ObjectiveTo compare nicotine absorption among children who are (1) exposed to secondhand tobacco smoke only or (2) exposed to secondhand vapor only with (3) those exposed to neither.Design, Setting, and ParticipantsThe US Continuous National Health and Nutrition Examination Survey (NHANES) is a repeat cross-sectional survey. Participants are interviewed in their homes and, several days after, visit a mobile examination center to provide biological specimens. This study uses data from a nationally representative sample of US households from 2017 to 2020. Participants were children aged 3 to 11 years with serum cotinine levels incompatible with current firsthand nicotine use (ie, <15 μg/L). The final analysis was conducted on January 9, 2024.ExposuresReported exposure to secondhand smoke or vapor indoors in the past 7 days (only secondhand smoke, only secondhand vapor, or neither). Covariates included age, sex, ethnicity, family income, body weight, and height.Main Outcomes and MeasuresThe primary outcome was serum cotinine concentration, an objective biomarker of nicotine absorption. Geometric mean cotinine levels and 95% CIs were calculated using log-normal tobit regression, accounting for the complex survey design and weights.ResultsThe mean (SD) age of the 1777 children surveyed was 7.4 (2.6) years, 882 (49.6%) were female, and 531 (29.9%) had family incomes below the poverty level. Nicotine absorption, as indexed by serum cotinine level, was highest among children only exposed to secondhand smoke (0.494 μg/L μg/L; 95% CI, 0.386-0.633 μg/L), followed by those exposed only to secondhand vapor (0.081 μg/L; 95% CI, 0.048-0.137 μg/L), equating to 83.6% (95% CI, 71.5%-90.5%; P < .001) lower nicotine absorption. Among children with no reported secondhand exposure, the geometric mean cotinine level was 0.016 μg/L (95% CI, 0.013-0.021 μg/L), or 96.7% (95% CI, 95.6%-97.6%; P < .001) lower than for those with exposure to secondhand smoke. Results were similar after covariate adjustment.Conclusions and RelevanceIn this cross-sectional study of US children, nicotine absorption was much lower in children who were exposed to secondhand vapor vs secondhand smoke, but higher than in those exposed to neither. These findings suggest that switching from smoking to vaping indoors may substantially reduce, but not eliminate, children’s secondhand exposure to nicotine and other noxious substances.

Cytotoxic impact of nicotine products on periodontal ligament cells

ObjectivesThe primary objective of this in vitro experiment was an assessment of proliferative capacity, metabolic activity, and potential cellular detriment of human periodontal ligament cells (hPDL) exposed to cigarette smoke (CS), electronic cigarette vapor (eCV), and heated tobacco product aerosol (HTP), or air (control).Materials and methodsUsing a CAD/CAM-designed exposition chamber, hPDL were exposed to CS, eCV, HTP, or air (control) based on the Health Canada Intense Smoking Regime. Cell proliferation, metabolic activity, and cellular detriment were assessed at various time points.ResultsCompared to the control, hPDL exposed to CS exhibited significantly decreased cell numbers at all time points. HTP exposure led to reduced cell numbers 48 h and 72 h post-exposure, while eCV-exposed cells showed no significant decrease. The metabolic activity of eCV-treated hPDL was slightly reduced at 7 h but recovered at 24 h and 48 h. In contrast, CS-treated cells exhibited significantly decreased metabolic activity at 24 h and 48 h, and HTP-exposed cells showed a significant decrease after 48 h. Flow cytometry indicated both apoptotic and necrotic cell death following CS exposure, with necrotic cell death being more pronounced.ConclusionseCV and HTP demonstrated comparatively reduced detrimental effects on hPDL compared to CS.Clinical relevance: The findings suggest that conventional cigarette smoke poses a substantial risk to periodontal health by significantly impairing cell proliferation and metabolic activity. However, alternatives such as eCV and HTP may offer a comparatively reduced risk.

Acute exposure to dihydroxyacetone promotes genotoxicity and chromosomal instability in lung, cardiac, and liver cell models.

Inhalation exposures to dihydroxyacetone (DHA) occur through spray tanning and e-cigarette aerosols. Several studies in skin models have demonstrated that millimolar doses of DHA are cytotoxic, yet the genotoxicity was unclear. We examined the genotoxicity of DHA in cell models relevant to inhalation exposures. Human bronchial epithelial cells BEAS-2B, lung carcinoma cells A549, cardiomyocyte Ac16, and hepatocellular carcinoma HepG3 were exposed to DHA, and low millimolar doses of DHA were cytotoxic. IC90 DHA doses induced cell cycle arrest in all cells except the Ac16. We examined DHA's genotoxicity using strand break markers, DNA adduct detection by Repair Assisted Damage Detection (RADD), metaphase spreads, and a forward mutation assay for mutagenesis. Similar to results for skin, DHA did not induce significant levels of strand breaks. However, RADD revealed DNA adducts were induced 24 h after DHA exposure, with BEAS-2B and Ac16 showing oxidative lesions and A549 and HepG3 showing crosslink-type lesions. Yet, only low levels of reactive oxygen species or advanced glycation end products were detected after DHA exposure. Metaphase spreads revealed significant increases in chromosomal aberrations in the BEAS-2B and HepG3 with corresponding changes in ploidy. Finally, we confirmed the mutagenesis observed using the supF reporter plasmid. DHA increased the mutation frequency, consistent with methylmethane sulfonate, a mutagen and clastogen. These data demonstrate DHA is a clastogen, inducing cell-specific genotoxicity and chromosomal instability. The specific genotoxicity measured in the BEAS-2B in this study suggests that inhalation exposures pose health risks to vapers, requiring further investigation.

Coverage of Indoor Smoking and Vaping Restrictions in the U.S., 1990–2021

Secondhand smoke exposure increases the risk of premature death and disease in children and non-smoking adults. As a result, many US states and local jurisdictions have enacted comprehensive indoor smoking restrictions (ISR). Indoor vaping restrictions (IVR) have also been adopted to protect against exposure to secondhand e-cigarette aerosol. This study aimed to quantify state and national US coverage of policies restricting indoor cigarette and e-cigarette use over time. Data from the American Nonsmokers Rights' Foundation on US ISR from 1990 to 2021 and IVR from 2006 to 2021 were analyzed. Combining these data with 2015 US Census population estimates, the percentage of state and national residents covered by partial and comprehensive restrictions in bars, restaurants, and workplaces, were calculated (analysis in 2023-2024) over time. Between 1990-2021, national coverage of comprehensive ISR increased for bars (0% to 67.3%), restaurants (0% to 78.2%), and workplaces (0% to 77.5%). Partial ISR coverage decreased for bars (14.8% to 13.9%), restaurants (40.2% to 15.4%) and workplaces (40.2% to 22.5%). From 2006 to 2021, comprehensive IVR coverage increased for bars (0% to 43.5%), restaurants (0% to 51.5%), and workplaces (0% to 53.2%). Despite these increases in coverage, by the end of 2021, <50% of the population was protected by comprehensive ISR for bars, restaurants, and workplaces in 19, 12, and 14 states, respectively. The percentage of the US population protected by ISR and IVR has increased over time. However, gaps in coverage remain, which may contribute to disparities in tobacco-related disease and death.

Different Lengths of Gestational Exposure to Secondhand Smoke or e-Cigarette Vapor Induce the Development of Placental Disease Symptoms.

Exposure to cigarette smoke is known to induce disease during pregnancy. Recent evidence showed that exposure to secondhand smoke (SHS) negatively impacts fetal and placental weights, leading to the development of intrauterine growth restriction (IUGR). Electronic cigarettes (eCigs) represent a phenomenon that has recently emerged, and their use is also steadily rising. Even so, the effects of SHS or eCigs during gestation remain limited. In the present study, we wanted to characterize the effects of SHS or eCig exposure at two different important gestational points during mouse pregnancy. C57/Bl6 mice were exposed to SHS or eCigs via a nose-only delivery system for 4 days (from 14.5 to 17.5 gestational days (dGA) or for 6 days (from 12.5 dGA to 17.5 dGA)). At the time of necropsy (18.5 dGA), placental and fetal weights were recorded, maternal blood pressure was determined, and a dipstick test to measure proteinuria was performed. Placental tissues were collected, and inflammatory molecules in the placenta were identified. Treatment with SHS showed the following: (1) a significant decrease in placental and fetal weights following four days of exposure, (2) higher systolic and diastolic blood pressure following six days of exposure, and (3) increased proteinuria after six days of exposure. Treatment with eCigs showed the following: (1) a significant decrease in placental weight and fetal weight following four or six days of exposure, (2) higher systolic and diastolic blood pressure following six days of exposure, and (3) increased proteinuria after six days of exposure. We also observed different inflammatory markers associated with the development of IUGR or PE. We conclude that the detrimental effects of SHS or eCig treatment coincide with the length of maternal exposure. These results could be beneficial in understanding the long-term effects of SHS or eCig exposure in the development of placental diseases.

Dual Exposure to E-Cigarette Vapour and Cigarette Smoke Results in Poorer Airway Cell, Monocyte, and Macrophage Function Than Single Exposure.

E-cigarette users predominantly also continue to smoke cigarettes. These Dual Users either consume e-cigarettes in locations where smoking is not allowed, but vaping is, or to reduce their consumption of cigarettes, believing it will lead to harm reduction. Whilst it is known that e-cigarette vapour is chemically less complex than cigarette smoke, it has a distinct chemical profile, and very little is known about the health impacts of exposure to both chemical profiles vs. either alone. We simultaneously exposed cells in vitro to non-toxic levels of e-cigarette vapour extract (EVE) and cigarette smoke extract (CSE) to determine their effects on 16HBE14o- airway epithelial cell metabolism and inflammatory response, as well as immune cell (THP-1 cells and monocyte-derived macrophages (MDM) from healthy volunteers) migration, phagocytosis, and inflammatory response. We observed increased toxicity, reduced metabolism (a marker of proliferation) in airway epithelial cells, and reduced monocyte migration, macrophage phagocytosis, and altered chemokine production after exposure to either CSE or EVE. These cellular responses were greater after dual exposure to CSE and EVE. The airway epithelial cells from smokers showed reduced metabolism after EVE (the Switcher model) and dual CSE and EVE exposure. When EVE and CSE were allowed to interact, the chemicals were found to be altered, and new chemicals were also found compared to the CSE and EVE profiles. Dual exposure to e-cigarette vapour and cigarette smoke led to worse functional outcomes in cells compared to either single exposure alone, adding to limited data that dual use may be more dangerous than smoking only.

Ozonolysis of Terpene Flavor Additives in Vaping Emissions: Elevated Production of Reactive Oxygen Species and Oxidative Stress.

The production of e-cigarette aerosols through vaping processes is known to cause the formation of various free radicals and reactive oxygen species (ROS). Despite the well-known oxidative potential and cytotoxicity of fresh vaping emissions, the effects of chemical aging on exhaled vaping aerosols by indoor atmospheric oxidants are yet to be elucidated. Terpenes are commonly found in e-liquids as flavor additives. In the presence of indoor ozone (O3), e-cigarette aerosols that contain terpene flavorings can undergo chemical transformations, further producing ROS and reactive carbonyl species. Here, we simulated the aging process of the e-cigarette emissions in a 2 m3 FEP film chamber with 100 ppbv of O3 exposure for an hour. The aged vaping aerosols, along with fresh aerosols, were collected to detect the presence of ROS. The aged particles exhibited 2- to 11-fold greater oxidative potential, and further analysis showed that these particles formed a greater number of radicals in aqueous conditions. The aging process induced the formation of various alkyl hydroperoxides (ROOH), and through iodometric quantification, we saw that our aged vaping particles contained significantly greater amounts of these hydroperoxides than their fresh counterparts. Bronchial epithelial cells exposed to aged vaping aerosols exhibited an upregulation of the oxidative stress genes, HMOX-1 and GSTP1, indicating the potential for inhalation toxicity. This work highlights the indirect danger of vaping in environments with high ground-level O3, which can chemically transform e-cigarette aerosols into new particles that can induce greater oxidative damage than fresh e-cigarette aerosols. Given that the toxicological characteristics of e-cigarettes are mainly associated with the inhalation of fresh aerosols in current studies, our work may provide a perspective that characterizes vaping exposure under secondhand or thirdhand conditions as a significant health risk.

Quantification of Free Radicals from Vaping Electronic Cigarettes Containing Nicotine Salt Solutions with Different Organic Acid Types and Concentrations.

Electronic (e-) cigarette formulations containing nicotine salts from a range of organic acid conjugates and pH values have dominated the commercial market. The acids in the nicotine salt formulations may alter the redox environment in e-cigarettes, impacting free radical formation in e-cigarette aerosol. Here, the generation of aerosol mass and free radicals from a fourth-generation e-cigarette device was evaluated at 2 wt % nicotine salts (pH 7, 30:70 mixture propylene glycol to vegetable glycerin) across eight organic acids used in e-liquids: benzoic acid (BA), salicylic acid (SLA), lactic acid (LA), levulinic acid (LVA), succinic acid (SA), malic acid (MA), tartaric acid (TA), and citric acid (CA). Furthermore, 2 wt % BA nicotine salts were studied at the following nicotine to acid ratios: 1:2 (pH 4), 1:1 (pH 7), and 2:1 (pH 8), in comparison with freebase nicotine (pH 10). Radical yields were quantified by spin-trapping and electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra of free radicals in the nicotine salt aerosol matched those generated from the Fenton reaction, which are primarily hydroxyl (OH) radicals and other reactive oxygen species (ROS). Although the aerosol mass formation was not significantly different for most of the tested nicotine salts and acid concentrations, notable ROS yields were observed only from BA, CA, and TA under the study conditions. The e-liquids with SLA, LA, LVA, SA, and MA produced less ROS than the 2 wt % freebase nicotine e-liquid, suggesting that organic acids may play dual roles in the production and scavenging of ROS. For BA nicotine salts, it was found that the ROS yield increased with a higher acid concentration (or a lower nicotine to acid ratio). The observation that BA nicotine salts produce the highest ROS yield in aerosol generated from a fourth-generation vape device, which increases with acid concentration, has important implications for ROS-mediated health outcomes that may be relevant to consumers, manufacturers, and regulatory agencies.

THE EFFECT OF GREEN TEA INFUSION (CAMELLIA SINENSIS) ON THE DIAMETER OF THE SPLEEN LYMPHATIC NODULUS OF MICE (MUS MUSCULUS) EXPOSED TO ELECTRIC CIGARETTE

E-cigarettes are the most widely used nicotine replacement therapy (NRT), particularly among young people. Exposure to e-cigarette vapor increases free radicals and suppresses the body's immune system. The accumulation of reactive oxygen species (ROS) in the spleen causes inflammation and tissue injury that decreases immune reactivity. It causes changes in the histoarchitecture of the spleen, including the lymphatic nodules. It might be repaired by the antioxidant and immunomodulatory activity of green tea that stimulates and enhances the immune system. Green tea polyphenols affect the production of cytokines along with the activation, proliferation, and differentiation of lymphocytes in the body. Increasing the diameter of the lymphatic nodules is an indicator of the immunomodulatory activity of green tea in mice exposed to e-cigarette vapor. The study design was a randomized post-test only controlled group with 27 sampled mice divided randomly into 3 groups, namely; P0 (e-cigarette vapor), P1 (e-cigarette vapor + green tea 0.020 g/bb/day), and P2 (e-cigarette vapor + green tea 0.040 g/bb/day). There were significant differences between the control and treatment groups, while between green tea doses of 0.020 g/bb/day and 0.040 g/bb/day was no significant difference. The study showed green tea infusion with an optimal dose of 0.020g/bb/day affected increasing the diameter of the spleen lymphatic nodules of mice exposed to e-cigarette vapor. Further research based on the difference in duration of infusion exposure and overall observation of the white pulp component are needed. Keywords : Green tea infusion, Lymphatic nodules, E-cigarette vapor.

Abstract PO2-28-03: E-Cigarette Aerosol Exposure: Unraveling the Nexus of Autophagy, Cancer Stem Cells, and EMT in Breast Cancer Metastasis

Abstract Electronic cigarettes (E-cigs) have emerged as a significant public health concern due to their increasing popularity. These products have been associated with various harmful effects on human health. In the United States, breast cancer is the most diagnosed cancer among women, and its recurrence and metastasis are primary contributors to morbidity and mortality. Two critical factors in cancer progression are Epithelial-mesenchymal transition (EMT) and Cancer stem-like cells (CSCs), both of which play pivotal roles in metastasis. As a result, targeting the signaling pathways involved in these processes has become a promising avenue for cancer therapy. Autophagy, a cellular process, has dual roles in cancer development depending on the cancer type and stage. Given these considerations, our hypothesis centers on disrupting the EMT-mediated metastatic cascade in breast cancer by targeting autophagy in Cancer Stem Cells (CSCs). To investigate this hypothesis, we conducted experiments using mouse breast epithelial cells (HC11) and Triple-negative mouse breast cancer cells (4T1) exposed to E-cig aerosol at the air-liquid interphase (ALI) for 1 hr followed by a 24 hr recovery period. Our findings indicate that exposure to E-cig aerosols led to a decrease in epithelial markers (E-Cadherin and β-catenin) and an increase in mesenchymal markers (N-Cadherin and Vimentin) in HC11 cells. This suggests that normal cells may acquire characteristics associated with solitary migration. Furthermore, we observed significant changes in the levels of autophagy-related proteins (LC3B, Beclin-1, ATG12, and ATG16) and upregulation of stem cell markers (OCT4, SOX2, NANOG, KLF4, and c-MYC) in response to E-cig aerosol exposure, both in HC11 and 4T1 cells. Additionally, these alterations extended to changes in the expression of genes associated with the Transforming Growth Factor-beta (TGF-β) signaling pathway, known to play a potential role in promoting EMT. Our results provide a deeper understanding of the interplay between EMT, CSCs, and the autophagy process in the context of ALI exposure in normal and cancer cells. This underscores the need for further research into the shared molecular mechanisms of these three processes to identify common therapeutic targets that can simultaneously affect them. Citation Format: Shilpa Thota, Rizwana Begum, Naveen Chintalaramulu, Biplov Sapkota, Abhishek Pandit. E-Cigarette Aerosol Exposure: Unraveling the Nexus of Autophagy, Cancer Stem Cells, and EMT in Breast Cancer Metastasis [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-28-03.

Nicotine inhalant via E-cigarette facilitates sensorimotor function recovery by upregulating neuronal BDNF-TrkB signalling in traumatic brain injury.

Traumatic brain injury (TBI) causes lifelong physical and psychological dysfunction in affected individuals. The current study investigated the effects of chronic nicotine exposure via E-cigarettes (E-cig) (vaping) on TBI-associated behavioural and biochemical changes. Adult C57/BL6J male mice were subjected to controlled cortical impact (CCI) followed by daily exposure to E-cig vapour for 6 weeks. Sensorimotor functions, locomotion, and sociability were subsequently evaluated by nesting, open field, and social approach tests, respectively. Immunoblots were conducted to examine the expression of mature brain-derived neurotrophic factor (mBDNF) and associated downstream proteins (p-Erk, p-Akt). Histological analyses were performed to evaluate neuronal survival and neuroinflammation. Post-injury chronic nicotine exposure significantly improved nesting performance in CCI mice. Histological analysis revealed increased survival of cortical neurons in the perilesion cortex with chronic nicotine exposure. Immunoblots revealed that chronic nicotine exposure significantly up-regulated mBDNF, p-Erk and p-Akt expression in the perilesion cortex of CCI mice. Immunofluorescence microscopy indicated that elevated mBDNF and p-Akt expression were mainly localized within cortical neurons. Immunolabelling of Iba1 demonstrated that chronic nicotine exposure attenuated microglia-mediated neuroinflammation. Post-injury chronic nicotine exposure via vaping facilitates recovery of sensorimotor function by upregulating neuroprotective mBDNF/TrkB/Akt/Erk signalling. These findings suggest potential neuroprotective properties of nicotine despite its highly addictive nature. Thus, understanding the multifaceted effects of chronic nicotine exposure on TBI-associated symptoms is crucial for paving the way for informed and properly managed therapeutic interventions.

Hepatic steatosis induced by nicotine plus Coca-Cola™ is prevented by nicotinamide riboside (NR).

Cigarettes containing nicotine (Nic) are a risk factor for the development of cardiovascular and metabolic diseases. We reported that Nic delivered via injections or e-cigarette vapor led to hepatic steatosis in mice fed with a high-fat diet. High-fructose corn syrup (HFCS) is the main sweetener in sugar-sweetened beverages (SSBs) in the US. Increased consumption of SSBs with HFCS is associated with increased risks of non-alcoholic fatty liver disease (NAFLD). Nicotinamide riboside (NR) increases mitochondrial nicotinamide adenine dinucleotide (NAD+) and protects mice against hepatic steatosis. This study evaluated if Nic plus Coca-Cola™ (Coke) with HFCS can cause hepatic steatosis and that can be protected by NR. C57BL/6J mice received twice daily intraperitoneal (IP) injections of Nic or saline and were given Coke (HFCS), or Coke with sugar, and NR supplementation for 10 weeks. Our results show that Nic+Coke caused increased caloric intake and induced hepatic steatosis, and the addition of NR prevented these changes. Western blot analysis showed lipogenesis markers were activated (increased cleavage of the sterol regulatory element-binding protein 1 [SREBP1c] and reduction of phospho-Acetyl-CoA Carboxylase [p-ACC]) in the Nic+Coke compared to the Sal+Water group. The hepatic detrimental effects of Nic+Coke were mediated by decreased NAD+ signaling, increased oxidative stress, and mitochondrial damage. NR reduced oxidative stress and prevented mitochondrial damage by restoring protein levels of Sirtuin1 (Sirt1) and peroxisome proliferator-activated receptor coactivator 1-alpha (PGC1) signaling. We conclude that Nic+Coke has an additive effect on producing hepatic steatosis, and NR is protective. This study suggests concern for the development of NAFLD in subjects who consume nicotine and drink SSBs with HFCS.

E-Cigarette Aerosol Alters Pulmonary Surfactant Function

Introduction: E-cigarette (EC) and vaping use continue to remain popular, particularly in young populations despite several clinical reports of vaping associated lung injury. One of the first compounds that EC aerosols comes into contact within the lungs during a deep inhalation is pulmonary surfactant. A complex mixture of lipids and proteins, surfactant reduces surface tension in the lungs maintaining compliance and preventing collapse. Currently, information on how EC aerosols impacts pulmonary surfactant remains limited, particularly in the in vivo scenario. We hypothesized that exposure to EC aerosol will impair the surface tension reducing ability of surfactant. Methods: In vitro EC aerosol exposure : Bovine Lipid Extract Surfactant (BLES) was used as a model surfactant in a direct exposure syringe system. BLES (2ml) was placed in a syringe (30ml) attached to an EC. The generated aerosol was drawn into the syringe and then expelled, repeated 30 times. In vivo EC aerosol exposure : Male and female Wistar rats were exposed to vehicle or menthol flavoured EC aerosol. Rats were exposed for 15 minutes for either a single or multiple (up to 8) exposures, with control animals receiving room air. Animals were euthanized and bronchoalveolar lavage was performed to collect surfactant. Analyzing surfactant function: Samples underwent dynamic compression and expansion, and biophysical analysis after exposure, completed using a constrained drop surfactometer (CDS). Results: Significant increases in minimum surface tensions were observed after exposure to EC aerosol across 20 compression/expansion cycles. Surfactant function was altered in vitro independent of vaping device, temperature, or inclusion of nicotine. Vehicle aerosol exposure produced alterations in surfactant properties, however addition of menthol flavouring significantly increased surface tensions compared to control and vehicle exposure. Preliminary in vivo studies indicate that aerosol exposure is well-tolerated by both male and female animals. Further experiments will analyze the function of surfactant isolated from these animals. Discussion: EC aerosols alter surfactant function through increases in minimum surface tension in vitro. This effect was more pronounced with menthol flavoured EC aerosol. It is anticipated that our in vivo experiments will corroborate these findings. Ultimately, impairment of surfactant due to EC aerosol exposure may contribute to lung dysfunction and susceptibility to further injury. Western University, NSERC, OGS. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

E-Cigarette Aerosol Inhibition of Compositionally Different Surfactants

Introduction: Pulmonary surfactant lines the alveolar surface where it reduces surface tension (ST) thereby facilitating breathing with minimal effort. As such, impairment of surfactant’s surface tension reducing function can contribute to lung injury. Isolated surfactant from the lung consists of up of 85-90% by weight saturated and unsaturated phospholipids, 5-10% neutral lipids, mainly cholesterol, and 10% surfactant proteins, designated SP-A, SP-B, and SP-C. However, studies examining surfactant function and dysfunction have often utilized surfactants with simpler compositions. One recent area of interest is the impact of e-cigarette (EC) generated aerosols on surfactant. EC use remains a popular habit despite reports of vaping associated acute lung injury. Upon inhalation, EC aerosol comes into direct contact with pulmonary surfactant and previous studies have demonstrated that EC aerosol exposure can impair surfactant function using either bovine lipid-extracted surfactant (BLES) or simple lipid mixtures. Comparing inhibition by EC aerosol of a more diverse set of surfactant preparations can further elucidate which components of surfactant are most affected by EC aerosol. We hypothesized that EC aerosol would cause varying degrees of functional inhibition in compositionally different surfactants. Methods: The following surfactant preparations were tested: BLES, BLES + SP-A, natural bovine, SP-A deficient bovine, and synthetic surfactants composed of saturated lipids + cholesterol + SP-C, and saturated + unsaturated lipids + cholesterol + SP-C. To test the exposure to EC aerosol, 2ml of surfactant was placed in a syringe (30ml) attached to an EC. The generated aerosol was drawn into the syringe for 30 sec and then expelled, this was repeated 30 times. The functional impact was then tested on a constrained sessile drop surfactometer to analyse changes in ST reduction. Results: Upon exposure to EC aerosol, natural bovine surfactant had significantly higher minimum ST compared to non-exposed and BLES. This difference did not appear to be mediated by SP-A. Synthetic lipid mixtures containing only saturated phospholipids (DPPC) were not significantly inhibited by EC aerosol, but the addition of unsaturated lipids resulted in increased minimum ST. Conclusion: Functional impairment of pulmonary surfactant due to EC aerosol is dependent on aerosol interaction with unsaturated lipids. This effect is more pronounced in natural complete surfactants. Western, NSERC, OGS. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Chronic e-cigarette use in young adults is associated with reduced cardiopulmonary function at rest and during exercise

E-cigarette aerosols produce contaminant particles that have the potential to impair cardiopulmonary function. However, the current understanding of the impact of e-cigarette use on cardiopulmonary function remains inconclusive. Exercise represents a stress on the cardiopulmonary system and may help identify cardiopulmonary dysfunction in chronic e-cigarette users. Consequently, the purpose of this study was to investigate if e-cigarette users exhibit cardiopulmonary abnormalities under physiological stress of exercise. To further investigate pulmonary vascular responses, the secondary purpose of the study was to examine how diffusing capacity (DLCO), pulmonary capillary blood volume (VC), and membrane diffusing capacity (DM) respond to positional changes, as the transition from the upright to supine position should increase DLCO, VC, and DM, secondarily to increased perfusion pressure. We hypothesized that e-cigarette users would exhibit impaired cardiopulmonary function during exercise and reduced pulmonary vascular responsiveness to postural changes. Six chronic e-cigarette (e-cig) users (age: 24±5yrs, 5±2 years of e-cigarette use) with &lt;5 pack years of traditional cigarette smoking history and six non-smoking controls who were age-, height-, and sex-matched completed two experimental trials. Day 1: Pulmonary function test and cardiopulmonary exercise test. Day 2: multiple fraction of inspired oxygen DLCO technique to quantify DLCO, VC, and DM at rest in the upright and supine positions. Resting pulmonary function was not significantly different between groups. The change in DLCO from upright to supine was significantly lower in e-cig users compared to controls (Control: 7.61±2.32 ml/min/mmHg vs. E-cig: 3.17±2.09 ml/min/mmHg; p=0.01), due to a smaller change in VC ( p=0.03), which suggests reduced pulmonary vascular distention in e-cig users. V̇O2peak was significantly lower in e-cig users compared to controls (Control: 4.4±1.2 L/min vs. E-cig: 2.6 ±0.7 L/min; p=0.01). E-cig users exhibited significantly elevated V̇E/ V̇CO2nadir ( p=0.02) indicating worse ventilatory effciency, and greater dyspnea relative to power output ( p=0.02) compared to controls. Preliminary findings suggest that e-cigarette use is associated with normal resting lung function but reduced pulmonary vascular distensibility. Further, e-cigarette users demonstrate ventilatory ineffciency and greater exertional dyspnea along with exercise intolerance. Canadian Institutes of Health Research. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Abstract 1142: Effect Of Chronic E-cigarette Nicotine Exposure On A Mouse Model Of Hind-limb Ischemia

Background: The rise of e-cigarette use in the United States has been rapid, yet its impact on peripheral artery disease (PAD) remains largely unexplored. This study investigates the relationship between e-cigarette use and PAD using a mouse ischemic hindlimb model. Method: Mice aged 6-8 weeks were divided into four groups. Three groups inhaled e-cigarette vapor continuously for 14, 20, or 28 days prior, and for 28 days after hindlimb ischemia (HLI) surgery, using an InExpose system (Figure 1). A control group was exposed to room air (RA) before and after HLI. Laser-Doppler perfusion imaging tracked hindlimb blood flow, and functional deficits were assessed using the modified ischemia scale. Figure 1: Methodology Results: Blood perfusion in the ischemic hindlimb of the e-cigarette groups (EC-14, EC-20, EC-28) was significantly lower than the non-vaping group at 21 days post-surgery. In the EC-14 group, perfusion improved after 10 days of vaping cessation (Figure 2). Additionally, there was a reduction in platelet and leukocyte counts in the e-cigarette groups compared to RA, with no difference in red blood cells. Necrosis and claw damage were observed in EC-20 and EC-28 groups but not in non-vaping mice. Figure 2: Representative images of perfusion recovery measured by LDPI. Conclusion: Chronic e-cigarette nicotine exposure impairs blood flow recovery and causes necrosis in mice with hind limb ischemia, potentially due to perturbed angiogenesis and arteriogenesis. This study highlights the detrimental effects of e-cigarette nicotine on vascular health.