A Review of Pulmonary Toxicity of Electronic Cigarettes in the Context of Smoking: A Focus on Inflammation

Variations in Adverse Events Typology Following E-Cigarette Use: The Role of Preexisting Medical Conditions

BACKGROUND

Electronic cigarettes (e-cigarettes) are often marketed as safer alternatives to traditional smoking, yet evidence suggests potential health risks, especially among vulnerable populations. This study examines the immediate adverse events following e-cigarette use in individuals with preexisting health conditions to better understand these risks.

METHODS

We conducted a STROBE-compliant observational study to identify specific preexisting medical conditions that may increase the risk of adverse events following e-cigarette use. A cross-sectional survey was deployed from January 3rd to March 3rd, 2023. A total of 4695 current and former e-cigarette users completed the survey. Logistic regression models were utilized to examine associations between 23 distinct preexisting conditions and 48 adverse events, adjusting for age, sex, race/ethnicity, education level, and income.

RESULTS

The analysis encompassed 4,421 respondents, demonstrating that individuals with solid organ transplants faced notably pronounced risks, with odds ratios indicating a seven-fold increase in mouth/tongue blisters (OR = 7.05), nearly five-fold for heart palpitations (OR = 4.92), and heartburn (OR = 4.79). Stem cell transplantation recipients also showed significantly heightened risks for similar adverse events, including mouth/tongue blisters (OR = 5.53) and heart palpitations (OR = 4.65). Metabolic diseases were linked to substantially increased odds of mouth/tongue blisters (OR = 5.63), hair loss (OR = 4.09), and migraine (OR = 3.50), highlighting a specific vulnerability to e-cigarette aerosol exposure among these groups.

CONCLUSION

The findings highlight the acute health risks associated with e-cigarette use in individuals with certain preexisting conditions. These results challenge the notion that e-cigarette use poses limited harm to human health and highlight the need for tailored public health strategies to protect vulnerable populations.

Social Media Marketing Strategies for Electronic Cigarettes: Content Analysis of Chinese Weibo Accounts

BACKGROUND

E-cigarettes have gained popularity among teenagers due to extensive marketing strategies on social media platforms. This widespread promotion is a risk factor, as it fosters more positive attitudes toward e-cigarette use among teenagers and increases the perception that using e-cigarettes is normal. Therefore, the marketing of e-cigarettes on social media is a serious global health concern, and its strategies and impact should be clearly identified.

OBJECTIVE

This study examined how e-cigarette companies popularize their products via Weibo and identified the specific strategies influencing the effectiveness of their marketing.

METHODS

In phase 1, we conducted a search on Qcc.com and identified 32 e-cigarette brands with active Weibo accounts between October 1 and December 31, 2020, along with 863 Weibo posts. The data were investigated through content analysis. The codebook was developed into four categories: (1) product and features, (2) sales and promotions, (3) social contact and interaction, and (4) restrictions and warnings. To further understand the factors influencing e-cigarette brand marketing, we conducted a multiple linear regression analysis.

RESULTS

Marketing tactics by e-cigarette companies on Chinese social media were documented, including emphasizing attractive product features, using trendy characters, implicit promotions, downplaying health concerns, and engaging with Weibo users in various ways. Out of 863 posts, 449 (52%) mentioned product characteristics. In 313 (36.3%) posts, visible figures were used to attract attention. Product promotion was absent in 762 (88.3%) posts, and purchase channels were not mentioned in 790 (98.3%) posts. Social interaction-related posts received attention (n=548, 63.5%), particularly those featuring hashtag content (n=538, 62.3%). Most posts did not include claims for restrictions on teenagers' purchases or use (n=687, 79.6%) or information on health warnings (n=839, 97.2%). Multiple linear regression analysis identified marketing strategies that effectively increase the exposure of e-cigarette posts on Weibo. Posts including engagement via posts encouraging reposts, comments, and likes (P<.001) and engagement topics related to e-cigarette brands were positively correlated with the number of reposts (P=.009). Posts highlighting nonmonetary incentives (P=.004), posts with age restriction statements (P<.001), engaging via stories and idea collection (P<.001), and engagement topics related to products (P<.001) and current affairs (P=.002) had a positive effect on the number of comments. Engagement topics related to brands (P<.001) or interactive sweepstakes (P<.001) had a positive effect on the number of likes.

CONCLUSIONS

E-cigarette posts on Weibo that focus on product features and social interaction attract public attention, especially from teenagers. Stricter regulations and monitoring should be adopted to restrict the social media marketing of e-cigarettes.

The Untapped Biomarker Potential of MicroRNAs for Health Risk-Benefit Analysis of Vaping vs. Smoking

Despite the popularity of electronic cigarettes (e-cigs) among adolescent never-smokers and adult smokers seeking a less pernicious substitute for tobacco cigarettes, the long-term health impact of vaping is largely unknown. Like cigarette smoke, e-cig vapor contains harmful and potentially harmful compounds, although in fewer numbers and at substantially lower concentrations. Many of the same constituents of e-cig vapor and cigarette smoke induce epigenetic changes that can lead to the dysregulation of disease-related genes. MicroRNAs (MiRNAs) are key regulators of gene expression in health and disease states. Extensive research has shown that miRNAs play a prominent role in the regulation of genes involved in the pathogenesis of smoking-related diseases. However, the use of miRNAs for investigating the disease-causing potential of vaping has not been fully explored. This review article provides an overview of e-cigs as a highly consequential electronic nicotine delivery system, describes trends in e-cig use among adolescents and adults, and discusses the ongoing debate on the public health impact of vaping. Highlighting the significance of miRNAs in cell biology and disease, it summarizes the published and ongoing research on miRNAs in relation to gene regulation and disease pathogenesis in e-cig users and in vitro experimental settings. It identifies gaps in knowledge and priorities for future research while underscoring the need for empirical evidence that can inform the regulation of tobacco products to protect youth and promote public health.

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.

Direct health implications of e-cigarette use: a systematic scoping review with evidence assessment

Background

E-cigarettes are often marketed as a less harmful alternative to traditional tobacco cigarettes. Despite their popularity, the evidence regarding their effects on human health remains unclear and is filled with complexities.

Objectives

This systematic review aims to elucidate the direct effects of electronic cigarette use on human health, carefully distinguishing between the specific characteristics of the populations studied.

Methodology

Adhering to the PRISMA guidelines, we conducted a comprehensive search in PubMed/Medline, Web of Science, Scopus, and Google Scholar databases without date restrictions, including articles in both Spanish and English. This approach enabled the identification and analysis of primary studies to understand the direct effect of electronic cigarettes on human health.

Results

A total of 33 studies were included that evaluated cardiovascular, pulmonary, renal, weight and fertility effects. Only five studies analyzed e-cigarettes in healthy populations and seven studies compared healthy individuals against smokers. The effects evaluated on smokers or former tobacco smokers were apparently positive, however, among healthy individuals, increased heart rate, mean arterial pressure, oxidative stress, alteration of respiratory epithelial cells and increased airflow resistance were found.

Conclusion

Smokers or former smokers who switch to e-cigarettes may reduce their exposure to carcinogens and lower their risk of developing severe health issues associated with conventional smoking. However, in healthy individuals who have never smoked traditional cigarettes, the use of e-cigarettes introduces several cardiovascular and respiratory adverse effects. These findings suggest that while e-cigarettes can be a strategic harm reduction tool for smokers, they are not a safe option for non-smokers.

GC/HRMS Analysis of E-Liquids Complements In Vivo Modeling Methods and can Help to Predict Toxicity

Tobacco smoking is a major risk factor for disease development, with the user inhaling various chemicals known to be toxic. However, many of these chemicals are absent before tobacco is "burned". Similar, detailed data have only more recently being reported for the e-cigarette with regards to chemicals present before and after the e-liquid is "vaped." Here, zebrafish were dosed with vaped e-liquids, while C57-BL/6J mice were vaped using nose-cone only administration. Preliminary assessments were made using e-liquids and GC/HRMS to identify chemical signatures that differ between unvaped/vaped and flavored/unflavored samples. Oxidative stress and inflammatory immune cell response assays were then performed using our in vivo models. Chemical signatures differed, e.g., between unvaped/vaped samples and also between unflavored/flavored e-liquids, with known chemical irritants upregulated in vaped and unvaped flavored e-liquids compared with unflavored e-liquids. However, when possible respiratory irritants were evaluated, these agents were predominantly present in only the vaped e-liquid. Both oxidative stress and inflammatory responses were induced by a menthol-flavored but not a tobacco-flavored e-liquid. Thus, chemical signatures differ between unvaped versus vaped e-liquid samples and also between unflavored versus flavored e-liquids. These flavors also likely play a significant role in the variability of e-liquid characteristics, e.g., pro-inflammatory and/or cytotoxic responses.

Abnormal expression profile of plasma exosomal microRNAs in exclusive electronic cigarette adult users

Background

Exposure to electronic cigarette (e-cigarette) aerosol has been linked to several health concerns, including DNA damage, elevated oxidative stress, the release of inflammatory cytokine, and dysfunctions in epithelial barriers. However, little is known about the effect of exclusive e-cigarette use on expression profiles of exosomal miRNAs, which play critical regulatory roles in many inflammatory responses and disease processes including cancer. We aim to compare the exosomal microRNA expression profile between exclusive e-cigarette users and normal controls without any tobacco product use (non-users).

Methods

Using plasma samples from 15 exclusive e-cigarette users and 15 non-users in the Population Assessment of Tobacco and Health (PATH) Wave 1 study (2013-2014), we examined exosomal microRNAs expression levels through Illumina NextSeq 500/550 sequencing. The differential analyses between exclusive e-cigarette users and non-users were examined using the generalized linear model approach in the DESeq2 package in R/Bioconductor after adjusting the significant confounding effect from race. Gene enrichment analyses were conducted on target genes regulated by significant microRNAs in the differential analyses. Further, molecular-based techniques using the micro RNA mimics and inhibitors were applied for the validation of the expressions of the micro RNAs in vitro.

Results

We identified four microRNAs that have significantly higher expression levels in exclusive e-cigarette users than non-users including hsa-miR-100-5p, hsa-miR-125a-5p, hsa-miR-125b-5p, and hsa-miR-99a-5p. GO enrichment analysis on the target genes regulated by the four microRNAs showed that dysregulation of the four microRNAs in exclusive e-cigarette users involved in multiple cell processes such as protein kinase binding and miRNA metabolic process. KEGG pathway enrichment analysis found the four upregulated miRNAs in exclusive e-cigarette users involved in many cancer pathways such as the non-small cell lung cancer, small cell lung cancer, pancreatic cancer, p53 signaling pathway, Hippo signaling pathway, HIF-1 signaling pathway, and MAPK signaling pathway. Overexpression of miRNA hsa-miR-125b-5p was shown to promote DNA damage in bronchial epithelia cells.

Conclusions

Four plasma exosomal microRNAs involved in cancer development had higher expression levels in exclusive e-cigarette users than non-users, which might indicate a potentially elevated risk of cancer among exclusive e-cigarette users.

Sex-specific lung inflammation and mitochondrial damage in a model of electronic cigarette exposure in asthma

The prevalence of electronic cigarette (EC) use among adult with asthma has continued to increase over time, in part due to the belief of being less harmful than smoking. However, the extent of their toxicity and the involved mechanisms contributing to the deleterious impact of EC exposure on patients with preexisting asthma have not been delineated. In the present project, we tested the hypothesis that EC use contributes to respiratory damage and worsening inflammation in the lungs of patients with asthma. To define the consequences of EC exposure in established asthma, we used a mouse model with/without preexisting asthma for short-term exposure to EC aerosols. C57/BL6J mice were sensitized and challenged with a DRA (dust mite, ragweed, Aspergillus fumigates, 200 µg/mL) mixture and exposed daily to EC with nicotine (2% nicotine in 30:70 propylene glycol: vegetable glycerin) or filtered air for 2 wk. The mice were evaluated at 24 h after the final EC exposure. After EC exposure in asthmatic mice, lung inflammatory cell infiltration and goblet cell hyperplasia were increased, whereas EC alone did not cause airway inflammation. Our data also show that mitochondrial DNA (mtDNA) content and a key mtDNA regulator, mitochondrial transcription factor A (TFAM), are reduced in asthmatic EC-exposed mice in a sex-dependent manner. Together, these results indicate that TFAM loss in lung epithelium following EC contributes to male-predominant sex pathological differences, including mitochondrial damage, inflammation, and remodeling in asthmatic airways.NEW & NOTEWORTHY Respiratory immunity is dysregulated in preexisting asthma, and further perturbations by EC use could exacerbate asthma severity. However, the extent of their toxicity and the involved mechanisms contributing to the deleterious impact of EC exposure on patients with preexisting asthma have not been delineated. We found that EC has unique biological impacts in lungs and potential sex differences with loss of TFAM, a key mtDNA regulator, in lung epithelial region from our animal EC study.

Accelerated epigenetic age, inflammation, and gene expression in lung: comparisons of smokers and vapers with non-smokers

BACKGROUND

Cigarette smoking and aging are the main risk factors for pulmonary diseases, including cancer. Epigenetic aging may explain the relationship between smoking, electronic cigarette vaping, and pulmonary health. No study has examined smoking and vaping-related epigenetic aging in relation to lung biomarkers.

METHODS

Lung epigenetic aging measured by DNA methylation (mAge) and its acceleration (mAA) was assessed in young (age 21-30) electronic cigarette vapers (EC, n = 14, including 3 never-smoking EC), smokers (SM, n = 16), and non-EC/non-SM (NS, n = 39). We investigated relationships of mAge estimates with chronological age (Horvath-mAge), lifespan/mortality (Grim-mAge), telomere length (TL-mAge), smoking/EC history, urinary biomarkers, lung cytokines, and transcriptome.

RESULTS

Compared to NS, EC and SM had significantly older Grim-mAge, shorter TL-mAge, significantly accelerated Grim-mAge and decelerated TL-mAge. Among SM, Grim-mAA was associated with nicotine intake and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL). For EC, Horvath-mAA was significantly correlated with puffs per day. Overall, cytokines (IL-1β, IL-6, and IL-8) and 759 transcripts (651 unique genes) were significantly associated with Grim-mAA. Grim-mAA-associated genes were highly enriched in immune-related pathways and genes that play a role in the morphology and structures of cells/tissues.

CONCLUSIONS

Faster lung mAge for SM is consistent with prior studies of blood. Faster lung mAge for EC compared to NS indicates possible adverse pulmonary effects of EC on biological aging. Our findings support further research, particularly on epigenetic markers, on effects of smoking and vaping on pulmonary health. Given that most EC are former smokers, further study is needed to understand unique effects of electronic cigarettes on biological aging.

Comparison of the toxicological potential of two JUUL ENDS products to reference cigarette 3R4F and filtered air in a 90-day nose-only inhalation toxicity study

Electronic nicotine delivery systems (ENDS) are generally recognized as less harmful alternatives for those who would otherwise continue to smoke cigarettes. The potential toxicity of aerosols generated from JUUL Device and Virginia Tobacco (VT3) or Menthol (ME3) JUULpods at 3.0% nicotine concentration was assessed in rats exposed at target aerosol concentrations of 1400 μg/L for up to 6 h/day on a 5 day/week basis for at least 90 days (general accordance with OECD 413). 3R4F reference cigarette smoke (250 μg/L) and Filtered Air were used as comparators. JUUL ENDS product aerosol exposures at >5x the 3R4F cigarette smoke level resulted in greater plasma nicotine and cotinine levels (up to 2x). Notable cigarette smoke related effects included pronounced body weight reductions in male rats, pulmonary inflammation evidenced by elevated lactate dehydrogenase, pro-inflammatory cytokines and neutrophils in bronchoalveolar lavage fluid, increased heart and lung weights, and minimal to marked respiratory tract histopathology. In contrast, ENDS aerosol exposed animals had minimal body weight changes, no measurable inflammatory changes and minimal to mild laryngeal squamous metaplasia. Despite the higher exposure levels, VT3 and ME3 did not result in significant toxicity or appreciable respiratory histopathology relative to 3R4F cigarette smoke following 90 days administration.

Molecular Imaging of Pulmonary Inflammation in Users of Electronic and Combustible Cigarettes: A Pilot Study

Electronic cigarette (EC) use has increased dramatically, particularly among adolescents and young adults, and, like cigarette use, can cause pulmonary inflammation and increase the risk of lung disease. Methods: This preliminary study used PET with 18F-6-(1/2)(2-fluoro-propyl)-4-methylpyridin-2-amine (18F-NOS) to quantify inducible nitric oxide synthase expression to characterize oxidative stress and inflammation in the lungs in vivo in 3 age- and sex-matched groups: 5 EC users, 5 cigarette smokers, and 5 controls who had never smoked or vaped. Results: EC users showed greater 18F-NOS nondisplaceable binding potential (BPND) than cigarette smokers (P = 0.03) and controls (P = 0.01), whereas BPND in cigarette smokers did not differ from that in controls (P > 0.1). 18F-NOS lung tissue delivery and inducible nitric oxide synthase distribution volume did not significantly differ among groups. Although there were no group differences in peripheral inflammatory biomarker concentrations, 18F-NOS BPND correlated with the proinflammatory cytokine tumor necrosis factor-α concentrations (rs = 0.87, P = 0.05) in EC users. Additionally, when EC users and cigarette smokers were pooled together, number of vaping episodes or cigarettes per day correlated with interleukin-6 levels (rs = 0.86, P = 0.006). Conclusion: This is the first PET imaging study to compare lung inflammation between EC and cigarette users in vivo. We found preliminary evidence that EC users have greater pulmonary inflammation than cigarette smokers and controls, with a positive association between pulmonary and peripheral measures of inflammation.

Misconceptions of Vaping Among Young Adults

Background Vaping is growing in popularity worldwide, especially among young adults. To develop effective tobacco prevention interventions, first, there must be an understanding of the attitudes and perceptions of young adults toward the use of vaping. Highlighting perception discrepancies between races may allow physicians to more effectively counsel their patients regarding the risks of vaping. Methodology We conducted an online survey using Amazon Mechanical Turk (MTurk, https://www.mturk.com/) to identify misconceptions about vaping among adults aged 18 to 24 years who currently vape. The survey consisted of 18 questions evaluating reasons for vaping, history of tobacco use, and thoughts on the adverse effects of vaping. The Penn State Electronic Cigarette Dependence Index was implemented to assess dependence. Exclusion criteria comprised respondents who did not vape and were under the age of 18 or over the age of 24. Results A total of 1,009 responses were received with 66% identifying as male (n = 667) and 33% (n = 332) identifying as female. Sixty-nine percent of patients smoked cigarettes or used another form of tobacco previously (n = 692). Of those respondents, 81% indicated that they had since quit using tobacco products (excluding vaping). Switching to vaping was the most common reason for quitting cigarettes or other forms of tobacco, with health concerns and social purposes being the second and third most common reasons provided, respectively. When asked whether vaping had negative health impacts, only 238 (24%) participants strongly agreed with this statement, while a majority (64%) neither agreed nor disagreed or only somewhat agreed. Most participants were white or Caucasian (n = 777). When asked whether smoking or vaping had more severe health implications, 55% of white or Caucasian participants, 41% of Asian participants, and 32% of black or African American participants indicated that vaping was worse than smoking cigarettes. The average Penn State dependence score was 8.7, suggesting medium dependence. Conclusions Our survey sample of 1,006 young adults who vape indicated that the majority did not perceive vaping as significantly harmful. A comprehensive smoking prevention policy, educational interventions, and quit support are needed to enhance awareness among young adults about the health effects associated with vaping. Such interventions should also consider the novel shift toward the replacement of smoking with vaping.

Impact of vaping on respiratory health

Widespread uptake of vaping has signaled a sea change in the future of nicotine consumption. Vaping has grown in popularity over the past decade, in part propelled by innovations in vape pen design and nicotine flavoring. Teens and young adults have seen the biggest uptake in use of vape pens, which have superseded conventional cigarettes as the preferred modality of nicotine consumption. Relatively little is known, however, about the potential effects of chronic vaping on the respiratory system. Further, the role of vaping as a tool of smoking cessation and tobacco harm reduction remains controversial. The 2019 E-cigarette or Vaping Use-Associated Lung Injury (EVALI) outbreak highlighted the potential harms of vaping, and the consequences of long term use remain unknown. Here, we review the growing body of literature investigating the impacts of vaping on respiratory health. We review the clinical manifestations of vaping related lung injury, including the EVALI outbreak, as well as the effects of chronic vaping on respiratory health and covid-19 outcomes. We conclude that vaping is not without risk, and that further investigation is required to establish clear public policy guidance and regulation.

Saliva and Lung Microbiome Associations with Electronic Cigarette Use and Smoking

The microbiome has increasingly been linked to cancer. Little is known about the lung and oral cavity microbiomes in smokers, and even less for electronic cigarette (EC) users, compared with never-smokers. In a cross-sectional study (n = 28) of smokers, EC users, and never-smokers, bronchoalveolar lavage and saliva samples underwent metatranscriptome profiling to examine associations with lung and oral microbiomes. Pairwise comparisons assessed differentially abundant bacteria species. Total bacterial load was similar between groups, with no differences in bacterial diversity across lung microbiomes. In lungs, 44 bacteria species differed significantly (FDR < 0.1) between smokers/never-smokers, with most decreased in smokers. Twelve species differed between smokers/EC users, all decreased in smokers of which Neisseria sp. KEM232 and Curvibacter sp. AEP1-3 were observed. Among the top five decreased species in both comparisons, Neisseria elongata, Neisseria sicca, and Haemophilus parainfluenzae were observed. In the oral microbiome, 152 species were differentially abundant for smokers/never-smokers, and 17 between smokers/electronic cigarette users, but only 21 species were differentially abundant in both the lung and oral cavity. EC use is not associated with changes in the lung microbiome compared with never-smokers, indicating EC toxicity does not affect microbiota. Statistically different bacteria in smokers compared with EC users and never-smokers were almost all decreased, potentially due to toxic effects of cigarette smoke. The low numbers of overlapping oral and lung microbes suggest that the oral microbiome is not a surrogate for analyzing smoking-related effects in the lung.

PREVENTION RELEVANCE

The microbiome affects cancer and other disease risk. The effects of e-cig usage on the lung microbiome are essentially unknown. Given the importance of lung microbiome dysbiosis populated by oral species which have been observed to drive lung cancer progression, it is important to study effects of e-cig use on microbiome.

Association between Dietary Anthocyanidins and Risk of Lung Cancer

Background: Anthocyanidins are a kind of water-soluble flavonoids widely found in flowers and fruits of many plants. Although the beneficial effect of anthocyanidins in cancer prevention has been discussed, the value of anthocyanidins in lung cancer prevention requires further investigation. In this study, we aimed to explore the role of dietary anthocyanidins in the prevention of lung cancer in population-based prospective studies. Methods: Data of participants in this study were collected from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated in Cox proportional hazards regression for the association of dietary anthocyanidins and lung cancer risk. The dose-response relationship was explored between total anthocyanidins and the incidence of lung cancer. Results: A total of 97,993 participants were included in this study. The calculated HRs showed a trend that a higher quartile of total anthocyanidins indicated lower risk of lung cancer after adjusting for covariates (HRQ4vsQ1: 0.63; 95% CI: 0.55,0.73; p for trend < 0.001). A non-linear association between total anthocyanidins and lung cancer risk was found in the restricted cubic spline model. Conclusion: A protective association between dietary anthocyanidins and risk of lung cancer in Americans was investigated.

Cytokine signature clusters as a tool to compare changes associated with tobacco product use in upper and lower airway samples

Inhalation exposure to cigarette smoke and e-cigarette aerosol is known to alter the respiratory immune system, particularly cytokine signaling. In assessments of health impacts of tobacco product use, cytokines are often measured using a variety of sample types, from serum to airway mucosa. However, it is currently unclear whether and how well cytokine levels from different sample types and the airway locations they represent are correlated, making comparing studies that utilize differing sample types challenging. To address this challenge, we compared baseline cytokine signatures in upper and lower airways and systemic samples and evaluated how groups of coexpressed cytokines change with tobacco product use. Matched nasal lavage fluid (NLF), nasal epithelial lining fluid (NELF), sputum, and circulating serum samples were collected from 14 nonsmokers, 13 cigarette smokers, and 17 e-cigarette users and analyzed for levels of 22 cytokines. Individual cytokine signatures were first compared across each sample type, followed by identification of cytokine clusters within each sample type. Identified clusters were then evaluated for potential alterations following tobacco product use using eigenvector analyses. Individual cytokine signatures in the respiratory tract were significantly correlated (NLF, NELF, and sputum) compared with randomly permutated signatures, whereas serum was not significantly different from random permutations. Cytokine clusters that were similar across airway sample types were modified by tobacco product use, particularly e-cigarettes, indicating a degree of uniformity in terms of how cytokine host defense and immune cell recruitment responses cooperate in the upper and lower airways. Overall, cluster-based analyses were found to be especially useful in small cohort assessments, providing higher sensitivity than individual signatures to detect biologically meaningful differences between tobacco use groups. This novel cluster analysis approach revealed that eigencytokine patterns in noninvasive upper airway samples simulate cytokine patterns in lower airways.

An assessment of vaping-induced inflammation and toxicity: A feasibility study using a 2-stage zebrafish and mouse platform

It is currently understood that tobacco smoking is a major cause of pulmonary disease due to pulmonary/lung inflammation. However, due to a highly dynamic market place and an abundance of diverse products, less is known about the effects of e-cigarette (E-cig) use on the lung. In addition, varieties of E-cig liquids (e-liquids), which deliver nicotine and numerous flavor chemicals into the lungs, now number in the 1000s. Thus, a critical need exists for safety evaluations of these E-cig products. Herein, we employed a "2-stage in vivo screening platform" (zebrafish to mouse) to assess the safety profiles of e-liquids. Using the zebrafish, we collected embryo survival data after e-liquid exposure as well as neutrophil migration data, a key hallmark for a pro-inflammatory response. Our data indicate that certain e-liquids induce an inflammatory response in our zebrafish model and that e-liquid exposure alone results in pro-inflammatory lung responses in our C57BL/6J model, data collected from lung staining and ELISA analysis, respectively, in the mouse. Thus, our platform can be used as an initial assessment to ascertain the safety profiles of e-liquid using acute inflammatory responses (zebrafish, Stage 1) as our initial metric followed by chronic studies (C57BL/6J, Stage 2).

E-Cigarette (E-Cig) Liquid Composition and Operational Voltage Define the In Vitro Toxicity of Δ8Tetrahydrocannabinol/Vitamin E Acetate (Δ8THC/VEA) E-Cig Aerosols

The 2019 United States outbreak of E-cigarette (e-cig), or Vaping, Associated Acute Lung Injury (EVALI) has been linked to presence of vitamin E acetate (VEA) in Δ8tetrahydrocannabinol (Δ8THC)-containing e-liquids, as supported by VEA detection in patient biological samples. However, the pathogenesis of EVALI and the complex physicochemical properties of e-cig emissions remain unclear, raising concerns on health risks of vaping. This study investigates the effect of Δ8THC/VEA e-liquids and e-cig operational voltage on in vitro toxicity of e-cig aerosols. A novel E-cigExposure Generation System platform was used to generate and characterize e-cig aerosols from a panel of Δ8THC/VEA or nicotine-based e-liquids at 3.7 or 5 V. Human lung Calu-3 cells and THP-1 monocytes were exposed to cell culture media conditioned with collected e-cig aerosol condensate at doses of 85 and 257 puffs/m2 lung surface for 24 h, whereafter specific toxicological endpoints were assessed (including cytotoxicity, metabolic activity, reactive oxygen species generation, apoptosis, and inflammatory cytokines). Higher concentrations of gaseous volatile organic compounds were emitted from Δ8THC/VEA compared with nicotine-based e-liquids, especially at 5 V. Emitted PM2.5 concentrations in aerosol were higher for Δ8THC/VEA at 5 V and averagely for nicotine-based e-liquids at 3.7 V. Overall, aerosols from nicotine-based e-liquids showed higher bioactivity than Δ8THC/VEA aerosols in THP-1 cells, with no apparent differences in Calu-3 cells. Importantly, presence of VEA in Δ8THC and menthol flavoring in nicotine-based e-liquids increased cytotoxicity of aerosols across both cell lines, especially at 5 V. This study systematically investigates the physicochemical and toxicological properties of a model of Δ8THC/VEA and nicotine e-cigarette condensate exposure demonstrating that pyrolysis of these mixtures can generate hazardous toxicants whose synergistic actions potentially drive acute lung injury upon inhalation.

The effect of emerging tobacco related products and their toxic constituents on thrombosis

Although conventional cigarette smoking is declining, emerging tobacco related products (ETRPs) are currently gaining ground, especially among the youth. These products include electronic cigarettes, waterpipes/hookah, cigars/cigarillo, smokeless tobacco, and heat-not-burn cigarettes. The observed increase in the use of ETRPs is multifactorial and complex but appears to be mainly driven by efforts from the major tobacco companies to reinvent themselves, and present more appealing and allegedly safe(r) tobacco products. However, it is becoming apparent that these products produce substantial amounts of toxic chemicals, many of which have been shown to exert negative health effects, including in the context of the cardiovascular system. Thus, there has been research efforts, albeit limited in general, to characterize the health impact of these products on occlusive/thrombotic cardiovascular diseases (CVD). In this review, we will discuss the potential impact of ETRPs on thrombosis-based CVD. Specifically, we will review how these products and the major chemicals they produce and/or emit can trigger key players in the process of thrombosis, namely inflammation, oxidative stress, platelets, coagulation, and the vascular endothelium, and the relationship between these effects.

From Tobacco Cigarettes to Electronic Cigarettes: The Two Sides of a Nicotine Coin

Tobacco smoking-related diseases, including cardiovascular disease, pulmonary disease, stroke, and cancer in multiple organ sites, are the leading causes of preventable death, worldwide. Youth electronic cigarette use (vaping) is an evolving public health problem in the United States and around the world. Many of the same toxicants and carcinogens present in tobacco smoke are also found in electronic cigarette vapor, although mostly at substantially lower levels. The reduced concentrations of these chemicals in electronic cigarette vapor may imply lower health risk; however, they cannot equate to no risk. To date, the long-term health consequences of vaping are largely unknown. This “Perspective” provides a concise chronology of events leading up to an unprecedented global challenge, namely the convergence of global tobacco epidemic and youth vaping epidemic. Current state of knowledge, outstanding questions in the field, present challenges, and future directions in research are highlighted. The existing data show a continued and dynamic evolution of the converged epidemics. The goal should be to prevent youth vaping while improving smoking cessation strategies. In smokers who are unable or unwilling to quit smoking, the objective should be to provide “provably” safe or less-harmful alternatives, which should “completely” or “substantially” substitute tobacco cigarettes.

E-cigarette Use Among Middle and High School Students in New York City Before and After Passage of Tobacco 21

Introduction

Despite declines in cigarette smoking in the US, electronic cigarette (e-cigarette) use has increased among middle and high school students. In 2014, New York City (NYC) implemented Tobacco 21 (T21) to prohibit sales to anyone under age 21. Our study goal was to measure the effectiveness of T21 on e-cigarette use.

Methods

We used the New York State (NYS) Youth Tobacco Survey—a biennial, school-based, self-administered survey. We explored middle (N = 5249) and high (N = 7296) school NYC students’ (male and female) current (past 30 days’) e-cigarette use from 2014 (pre-T21) to 2018 (post-T21). Results were compared with students in the rest of NYS (ROS). Bivariate and multivariable logistic regression analyses assessed correlates of e-cigarette use, beliefs about harmfulness, addictiveness, and susceptibility.

Results

NYC high school students’ current e-cigarette use increased from 2014 to 2018 (8.1% vs 23.5%, P < .001). Middle school students’ use increased between 2014 (4.8%) and 2016 (9.0%) yet reversed by 2018 (5.7%) (2014 vs 2018, P = .576). ROS middle school (2.2% vs 7.4%, P < .001) and high school (12.0% vs 29.3%, (P < .001) use increased from 2014 to 2018. Willingness to try e-cigarettes among those who had never tried an e-cigarette was twice as high (AOR = 2.19, 95% CI = 1.15-3.17) among NYC high school students in 2018 compared with 2014.

Conclusions

E-cigarette use increased among NYC high school students despite T21. T21 may have reduced use among middle school students over time. Programs that denormalize e-cigarettes and policies that further restrict access are needed to decrease youth e-cigarette use.

In Vitro Systems for Toxicity Evaluation of Microbial Volatile Organic Compounds on Humans: Current Status and Trends

Microbial volatile organic compounds (mVOC) are metabolic products and by-products of bacteria and fungi. They play an important role in the biosphere: They are responsible for inter- and intra-species communication and can positively or negatively affect growth in plants. But they can also cause discomfort and disease symptoms in humans. Although a link between mVOCs and respiratory health symptoms in humans has been demonstrated by numerous studies, standardized test systems for evaluating the toxicity of mVOCs are currently not available. Also, mVOCs are not considered systematically at regulatory level. We therefore performed a literature survey of existing in vitro exposure systems and lung models in order to summarize the state-of-the-art and discuss their suitability for understanding the potential toxic effects of mVOCs on human health. We present a review of submerged cultivation, air-liquid-interface (ALI), spheroids and organoids as well as multi-organ approaches and compare their advantages and disadvantages. Furthermore, we discuss the limitations of mVOC fingerprinting. However, given the most recent developments in the field, we expect that there will soon be adequate models of the human respiratory tract and its response to mVOCs.

Profiles of Nicotine and Cannabis Exposure among Young Adults with Asthma

There is a paucity of data on nicotine and cannabis use among young adults (YAs) with asthma. This study aimed to do the following among YAs with asthma: (1) describe YAs' active and passive exposure to nicotine and cannabis; (2) identify latent classes of active use of nicotine and cannabis; and (3) explore predictors of class membership (i.e., demographics, parental and friend use of nicotine and cannabis, and hours of environmental exposure to tobacco smoke, e-cigarette vapor, and marijuana smoke). YAs with asthma (N = 178) self-reported on nicotine and cannabis exposure and the included covariates. Latent class analysis was used to identify latent classes of lifetime nicotine and cannabis use. High rates of nicotine and cannabis use among YAs with asthma were found: 37% reporting a lifetime history of using both nicotine and cannabis. Regarding past year use, 25% had smoked cigarettes, 40% had used e-cigarettes, and 35% had used cannabis. Five classes of lifetime use were identified. The largest class was a non-user class (53%); the other four classes indicate concerning patterns of nicotine and cannabis use. The most consistent predictor of being in a class characterized by more nicotine and cannabis exposure (versus being in the non-user class) was past week exposure to cannabis smoke. This is the first study to identify classes of lifetime nicotine and cannabis use, and examine predictors of class membership, among YAs with asthma. There is a critical need to address environmental and active tobacco and marijuana exposure among YAs with asthma.

A novel role for vaping in mitochondrial gene dysregulation and inflammation fundamental to disease development

We constructed and analyzed the whole transcriptome in leukocytes of healthy adult vapers (with/without a history of smoking), ‘exclusive’ cigarette smokers, and controls (non-users of any tobacco products). Furthermore, we performed single-gene validation of expression data, and biochemical validation of vaping/smoking status by plasma cotinine measurement. Computational modeling, combining primary analysis (age- and sex-adjusted limmaVoom) and sensitivity analysis (cumulative e-liquid- and pack-year modeling), revealed that ‘current’ vaping, but not ‘past’ smoking, is significantly associated with gene dysregulation in vapers. Comparative analysis of the gene networks and canonical pathways dysregulated in vapers and smokers showed strikingly similar patterns in the two groups, although the extent of transcriptomic changes was more pronounced in smokers than vapers. Of significance is the preferential targeting of mitochondrial genes in both vapers and smokers, concurrent with impaired functional networks, which drive mitochondrial DNA-related disorders. Equally significant is the dysregulation of immune response genes in vapers and smokers, modulated by upstream cytokines, including members of the interleukin and interferon family, which play a crucial role in inflammation. Our findings accord with the growing evidence on the central role of mitochondria as signaling organelles involved in immunity and inflammatory response, which are fundamental to disease development.

Vaping and psychotic experiences among college students in the United States

AIM

While cigarette and marijuana use has been linked to psychotic experiences, few empirical studies have examined the relation between vaping and psychotic experiences.

METHODS

We analyzed data from the Healthy Minds Survey (September 2020 - December 2020; N = 29,232 students from 36 universities), and used multiple logistic regression models to examine the associations between vaping over the past 30 days and psychotic experiences over the past 12 months, adjusting for age, gender, and race/ethnicity. We then additionally adjusted for cigarette and marijuana use, as well as depression and anxiety.

RESULTS

Roughly 14 % of students in the sample reported psychotic experiences over the past year, and around 14-15 % of students reported vaping over the past month. In multiple logistic regression models, vaping was significantly associated with psychotic experiences (aOR 1.88; 95 % CI: 1.63-2.18). This association attenuated but remained statistically significant even after adjusting for any cigarette use and marijuana use, and after adjusting for depression and anxiety.

CONCLUSIONS

Among college students, vaping was significantly associated with psychotic experiences, even after accounting for simple measures of cigarette and marijuana use, and mental health problems, calling for more prospective studies to examine the association.

Biomarkers of Inflammation and Oxidative Stress among Adult Former Smoker, Current E-Cigarette Users-Results from Wave 1 PATH Study

BACKGROUND

Former smokers who currently use e-cigarettes have lower concentrations of biomarkers of tobacco toxicant exposure than current smokers. It is unclear whether tobacco toxicant exposure reductions may lead to health risk reductions.

METHODS

We compared inflammatory biomarkers (high-sensitivity C-reactive protein, IL6, fibrinogen, soluble intercellular adhesion molecule-1) and an oxidative stress marker (F2-isoprostane) among 3,712 adult participants in Wave 1 (2013-2014) of the Population Assessment of Tobacco and Health Study by tobacco user groups: dual users of cigarettes and e-cigarettes; former smokers who currently use e-cigarettes-only; current cigarette-only smokers; former smokers who do not currently use any tobacco; and never tobacco users. We calculated geometric means (GM) and estimated adjusted GM ratios (GMR).

RESULTS

Dual users experienced greater concentration of F2-isoprostane than current cigarette-only smokers [GMR 1.09 (95% confidence interval, CI, 1.03-1.15)]. Biomarkers were similar between former smokers who currently use e-cigarettes and both former smokers who do not use any tobacco and never tobacco users, but among these groups most biomarkers were lower than those of current cigarette-only smokers. The concentration of F2-isoprostane decreased by time since smoking cessation among both exclusive e-cigarette users (P trend = 0.03) and former smokers who do not currently use any tobacco (P trend = 0.0001).

CONCLUSIONS

Dual users have greater concentration of F2-isoprostane than smokers. Exclusive e-cigarette users have biomarker concentrations that are similar to those of former smokers who do not currently use tobacco, and lower than those of exclusive cigarette smokers.

IMPACT

This study contributes to an understanding of the health effects of e-cigarettes.

E-cigarettes induce toxicity comparable to tobacco cigarettes in airway epithelium from patients with COPD

BACKGROUND

The health effects of e-cigarettes in patients with pre-existing lung disease are unknown. The aim of this study was to investigate whether aerosols from a fourth-generation e-cigarette produces similar in-vitro cytotoxic, DNA damage and inflammatory effects on bronchial epithelial cells (BECs) from patients with COPD, as cigarette smoke.

METHODS

BECs from patients with COPD who underwent surgery for lung cancer and comparator (immortalised 16HBE) cells were grown at air liquid interface (ALI). BECs were exposed to aerosols from a JUUL® e-cigarette (Virginia Tobacco and Menthol pods at 5% nicotine strength) or reference 3R4F cigarette for 30 min at ALI. Cell cytotoxicity, DNA damage and inflammation were measured.

RESULTS

In response to the Virginia Tobacco and Menthol flavoured e-cigarette aerosols, COPD BECs showed comparable LDH release (cell cytotoxicity, p = 0.59, p = 0.67 respectively), DNA damage (p = 0.41, p = 0.51) and inflammation (IL-8, p = 0.20, p = 0.89 and IL-6, p = 0.24, p = 0.93), to cigarette smoke. 16HBE cells also showed comparable cellular responses to cigarette smoke.

CONCLUSION

In airway cells from patients with COPD, aerosols from a fourth-generation e-cigarette were associated with similar toxicity to cigarette smoke. These results have potential implications for the safety of e-cigarette use in patients with lung disease.

Disease-related blood-based differential methylation in cystic fibrosis and its representation in lung cancer revealed a regulatory locus in PKP3 in lung epithelial cells

Cystic fibrosis (CF) is a monogenic disease, characterized by massive chronic lung inflammation. The observed variability in clinical phenotypes in monozygotic CF twins is likely associated with the extent of inflammation. This study sought to investigate inflammation-related aberrant DNA methylation in CF twins and to determine to what extent acquired methylation changes may be associated with lung cancer.

Blood-based genome-wide DNA methylation analysis was performed to compare the DNA methylomes of monozygotic twins, from the European CF Twin and Sibling Study with various degrees of disease severity. Putatively inflammation-related and differentially methylated positions were selected from a large lung cancer case-control study and investigated in blood by targeted bisulphite next-generation-sequencing. An inflammation-related locus located in the Plakophilin-3 (PKP3) gene was functionally analysed regarding promoter and enhancer activity in presence and absence of methylation using luciferase reporter assays.

We confirmed in a unique cohort that monozygotic twins, even if clinically discordant, have only minor differences in global DNA methylation patterns and blood cell composition. Further, we determined the most differentially methylated positions, a high proportion of which are blood cell-type-specific, whereas others may be acquired and thus have potential relevance in the context of inflammation as lung cancer risk factors. We identified a sequence in the gene body of PKP3 which is hypermethylated in blood from CF twins with severe phenotype and highly variably methylated in lung cancer patients and controls, independent of known clinical parameters, and showed that this region exhibits methylation-dependent promoter activity in lung epithelial cells.

Acute vaping exacerbates microbial pneumonia due to calcium (Ca2+) dysregulation

As electronic cigarette (E-cig) use, also known as "vaping", has rapidly increased in popularity, data regarding potential pathologic effects are recently emerging. Recent associations between vaping and lung pathology have led to an increased need to scrutinize E-cigs for adverse health impacts. Our previous work (and others) has associated vaping with Ca2+-dependent cytotoxicity in cultured human airway epithelial cells. Herein, we develop a vaped e-liquid pulmonary exposure mouse model to evaluate vaping effects in vivo. Using this model, we demonstrate lung pathology through the use of preclinical measures, that is, the lung wet: dry ratio and lung histology/H&E staining. Further, we demonstrate that acute vaping increases macrophage chemotaxis, which was ascertained using flow cytometry-based techniques, and inflammatory cytokine production, via Luminex analysis, through a Ca2+-dependent mechanism. This increase in macrophage activation appears to exacerbate pulmonary pathology resulting from microbial infection. Importantly, modulating Ca2+ signaling may present a therapeutic direction for treatment against vaping-associated pulmonary inflammation.

Electronic Cigarette Exposure Enhances Lung Inflammatory and Fibrotic Responses in COPD Mice

Although a few studies show that the use of electronic nicotine delivery systems (ENDS) may ameliorate objective and subjective outcomes in COPD smokers who switched to electronic cigarettes, it is unclear whether e-cigarette exposure alters lung pathological features and inflammatory response in COPD. Here, we employed βENaC-overexpressing mice bearing COPD-like pulmonary abnormality, and exposed them to ENDS. We found that ENDS exposure aggravated airspace enlargement and mucus production in βENaC-overexpressing mice, which was associated with increased MMP12 and Muc5ac, respectively. ENDS exposure to mice significantly increased the numbers of macrophages, particularly in M2 macrophages in bronchoalveolar lavage (BAL) fluid, despite ENDS did not induce M2 macrophage polarization in a cultured murine macrophage cell line (RAW264.7). There were no changes in neutrophils in BAL fluid by ENDS exposure. Multiple cytokine productions were increased including M-CSF, IL-1rα, IL-10, and TGF-β1, in BAL fluid from mice when exposed to ENDS. The Sirius Red staining and hydroxyproline assay showed ENDS-exposed mice displayed enhanced fibrotic phenotypes compared to control mice. In conclusion, ENDS exposure enhances airspace enlargement, mucus secretion, and fibrogenesis in COPD mice. This is associated with increased MMP12, inflammatory responses, and M2 macrophage phenotype. This study provides pre-clinical data implicating that electronic cigarette exposure is not safe in COPD patients who want to replace traditional cigarettes with ENDS.

The consequential impact of JUUL on youth vaping and the landscape of tobacco products: The state of play in the COVID-19 era

JUUL is a groundbreaking electronic cigarette (e-cig) and the preeminent vaping product on the market. We present an overview of the rapid and spectacular rise of JUUL and its remarkable fall within the timespan of 2015 - 2020. We highlight JUUL's entering the market in June 2015, becoming the industry leader in mid 2017, and experiencing a litany of setbacks by late 2019 through to early 2020. We address the role played by JUUL in the ongoing epidemic of youth vaping. We also feature competing views on the public health impact of JUUL use (in particular), and e-cig vaping (in general). We further highlight the latest trends in youth vaping and sales records for JUUL and tobacco cigarettes. In view of the ongoing pandemic of COVID-19, we briefly summarize the existing evidence on the relationship between vaping and smoking and the prevalence, disease course, and clinical outcomes of COVID-19.

Increased Expression of Proatherogenic Proteins in Immune Cell Subtypes in Tobacco Cigarette Smokers But Not in Electronic Cigarette Vapers

It is unclear how oxidative stress triggered by smoking and vaping may alter specific immune cell subsets. In this study, we showed that tobacco cigarette smoking, but not electronic-cigarette vaping, is associated with increased expression of major proteins in the toll-like receptor 4 (TLR4) inflammasome-interleukin (IL)-6 signalling axis in monocyte subtypes and T cells. TLR4 senses oxidative stress in immune cells caspase-1 is a key protein of inflammasome activation, and IL-6R-α is the receptor for IL-6 that drives proatherogenic IL-6 signalling. These findings implicate the non-nicotine, pro-oxidant toxicants in tobacco cigarette smoke as instigators of increased expression of key proteins in the TLR4-inflammasome-IL-6 axis that contribute to atherogenesis.

Antioxidants in smokers

Cigarette smoke (CS) is likely the most common preventable cause of human morbidity and mortality worldwide. Consequently, inexpensive interventional strategies for preventing CS-related diseases would positively impact health systems. Inhaled CS is a powerful inflammatory stimulus and produces a shift in the normal balance between antioxidants and oxidants, inducing oxidative stress in both the respiratory system and throughout the body. This enduring and systemic pro-oxidative state within the body is reflected by increased levels of oxidative stress and inflammation biomarkers seen in smokers. Smokers might benefit from consuming antioxidant supplements, or a diet rich in fruit and vegetables, which can reduce the CS-related oxidative stress. This review provides an overview of the plasma profile of antioxidants observable in smokers and examines the heterogeneous literature to elucidate and discuss the effectiveness of interventional strategies based on antioxidant supplements or an antioxidant-rich diet to improve the health of smokers. An antioxidant-rich diet can provide an easy-to-implement and cost-effective preventative strategy to reduce the risk of CS-related diseases, thus being one of the simplest ways for smokers to stay in good health for as long as possible. The health benefits attributable to the intake of antioxidants have been observed predominantly when these have been consumed within their natural food matrices in an optimal antioxidant-rich diet, while these preventive effects are rarely achieved with the intake of individual antioxidants, even at high doses.

Effects of E-Cigarette Aerosols with Varying Levels of Nicotine on Biomarkers of Oxidative Stress and Inflammation in Mice

To provide insights into the cause of e-cigarette (e-cig) associated lung injury, we examined the effects of propylene glycol (PG) and glycerol (G), two common solvent carriers used to deliver nicotine/flavor, on markers of oxidative stress and inflammation in female B6C3F1 mice which had been used successfully in tobacco smoke (TS)-induced lung carcinogenesis. Mice exposed to air and TS were used as negative and positive controls, respectively. Using LC-MS/MS, we showed that PG/G alone, in the absence of nicotine, significantly increased the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG or its tautomer 8-oxodG), a biomarker of DNA oxidative damage, in lung and plasma of mice; moreover, addition of nicotine (12 and 24 mg/mL) in e-cig liquid appears to suppress the levels of 8-oxodG. Exposure to e-cig aerosols or TS induced nonsignificant increases of plasma C-reactive protein (CRP), a biomarker of inflammation; nonetheless, the levels of fibronectin (FN), a biomarker of tissue injury, were significantly increased by e-cig aerosols or TS. Although preliminary, our data showed that exposure to e-cig aerosols induced a higher score of lung injury than did control air or TS exposure. Our results indicate that the B6C3F1 mouse model may be suitable for an in-depth examination of the impact of e-cig on lung injury associated with oxidative stress and inflammation and this study adds to the growing evidence that the use of e-cig can lead to lung damage.

Electronic Cigarette Liquid Constituents Induce Nasal and Tracheal Sensory Irritation in Mice in Regionally Dependent Fashion

INTRODUCTION

Electronic cigarettes (e-cigs) are currently used by millions of adults and adolescents worldwide. Major respiratory symptoms, such as coughing reported by e-cig users, including patients with e-cig, or vaping, product use-associated lung injury (EVALI), indicate e-cig constituent-induced sensory irritation. However, e-cig constituent-induced nociceptive activity in nasal and tracheal respiratory epithelia (RE) and neuronal activation in the trigeminal ganglia and brainstem nuclei, which receive airway chemosensory inputs have not been examined and compared. Comparisons of physiological responses between freebase nicotine and nicotine salts are also missing.

AIMS AND METHODS

Event-related potential (ERP) was recorded electrophysiologically to assess mouse nasal and tracheal RE chemosensory responses to various flavorings, nicotine, including freebase and nicotine salts, e-liquid mixtures, and tussigenic stimuli. Also, mice were subjected to inhalation exposure to aerosol of a vanilla-flavored e-liquid or air (control), and the activated-trigeminal nociceptive neurons and brainstem neurons were examined using immunohistochemistry.

RESULTS

Individual constituents and mixtures of e-liquids, capsaicin, and citric and acetic acids evoked significantly larger ERP in the nose than in the trachea with the exception of menthol. ERP responses to freebase nicotine were significantly larger than protonated nicotine. Four nicotine salts (benzoate, lactate, levulinate, and salicylate) induced similar responses. Compared with air-exposed mice, e-liquid aerosol-exposed mice showed a significant increase in numbers of activated trigeminal nociceptive neurons and brainstem neurons in the spinal trigeminal nucleus, paratrigeminal nucleus, and nucleus tractus solitarius.

CONCLUSIONS

E-liquid constituents region-dependently stimulate airway nociceptive chemosensory systems, and freebase nicotine is more potent than protonated nicotine.

IMPLICATIONS

Neural abnormalities have been implicated in the development of nasal and respiratory illnesses. The higher sensitivity of the nasal nociceptive chemosensory system to nicotine and flavorings may indicate a health risk for e-liquid aerosol-induced upper airway illnesses via neurogenic alteration and warrants further investigation.

Exposure to Secondhand Heated-Tobacco-Product Aerosol May Cause Similar Incidence of Asthma Attack and Chest Pain to Secondhand Cigarette Exposure: The JASTIS 2019 Study

Although secondhand cigarette smoke is known to cause various health consequences, even the short-term effects of exposure to secondhand heated-tobacco-product (HTP) aerosol are unknown. The purpose of this study was to examine short-term symptoms related to secondhand HTP aerosol exposure. An internet-based self-reported questionnaire survey was conducted in 2019 as a part of the Japan Society and New Tobacco Internet Survey (JASTIS) study. In total, 8784 eligible respondents aged 15-73 years were analyzed. We examined the frequency (%) of secondhand combustible cigarette smoke and HTP aerosol exposure, and the exposure-related subjective symptoms (sore throat, cough, asthma attack, chest pain, eye pain, nausea, headache, and other symptoms). Overall, 56.8% of those exposed to secondhand cigarette smoke had any subjective symptoms, compared to 39.5% of those exposed to HTP aerosol. Asthma attack and chest pain were reported more frequently when associated with secondhand HTP exposure (10.9 and 11.8%, respectively) than with secondhand cigarette smoke exposure (8.4 and 9.9%, respectively). Sore throat, cough, eye pain, nausea, and headache were also more frequently reported when associated with secondhand cigarette smoke than with secondhand HTP exposure. This is the first study to examine severe subjective symptoms such as asthma attacks and chest pains, and to suggest that respiratory and cardiovascular abnormalities could be related to secondhand heated-tobacco-product aerosol exposure. Further careful investigations are necessary.

Use of e-Cigarettes and Development of Respiratory Conditions in Women of Childbearing Age

OBJECTIVE

Women of childbearing age are encouraged not to smoke because of well-documented adverse health outcomes. This study examines the association between e-cigarette use and respiratory conditions (asthma and chronic obstructive pulmonary disease [COPD]) among women of childbearing age.

METHODS

The study used data from the Behavioral Risk Factor Surveillance System 2016-2017. The sample consisted of 131,965 women of childbearing age (18-44 years old). The main independent variable was smoking status and the primary outcomes were self-reported respiratory conditions such as asthma and COPD. Data were analyzed using descriptive statistics and multivariate logistic regression to assess the effects of e-cigarettes on asthma and COPD.

RESULTS

In this sample of childbearing-age women, 2.79% were current e-cigarettes users with or without a history of combustible cigarette smoking and 3.02% were current dual users. Compared with nonsmokers, current e-cigarette users without a history of combustible cigarette smoking were associated with 74% higher odds of having asthma (adjusted odds ratio [AOR] 1.74, 95% confidence interval [CI] 1.29-2.35), whereas results were not significant for COPD. The odds of having COPD, however, were 3 times higher (AOR 3.28, 95% CI 2.62-4.12) for current e-cigarette users with a history of cigarette smoking, whereas current dual users showed 5 times higher odds (AOR 5.07, 95% CI 3.91-6.56) of COPD compared with nonsmokers.

CONCLUSION

Policies related to e-cigarettes need to be reevaluated and clearly communicated to improve prevention efforts for women of childbearing age.

The inflammatory biomarker YKL-40 is elevated in the serum, but not the sputum, of E-cigarette users

METHODS

We conducted a cross-sectional study of adults between 18 and 55 years old. Inclusion criteria were: exclusive e-cigarette use or cigarette smoking for ≥ 1 year or no history of tobacco use. Participants with a history of pulmonary illness, atopy, medications (except birth control pills), marijuana, and illegal substance use were excluded. Custom Multiplex ELISA was used to measure YKL-40 and other biomarker levels in the serum and induced sputum of the participants. Multivariable linear regression was used to compare the levels of YLK-40 in healthy participants, e-cigarette, and cigarette users after adjusting for age, sex, and BMI.

RESULTS

We recruited 20 healthy controls, 23 cigarette smokers, and 22 exclusive e-cigarette users. Serum YKL-40 (ng/ml) was significantly higher in e-cigarette users (Median 21.2 [IQR 12.1-24.0] ng/ml) when compared to controls (12.2 [IQR 8.7-18.1] ng/ml, p = 0.016) but comparable to cigarette smokers (21.6 [IQR 11.62-51.7] ng/ml, p = 0.31). No significant differences were found in the serum or sputum of the other biomarkers tested.

CONCLUSION

The inflammatory biomarker, YKL-40 is elevated in the serum but not the sputum of e-cigarette users with no reported pulmonary disease. Further research is necessary to characterize this association.

Recent updates on biomarkers of exposure and systemic toxicity in e-cigarette users and EVALI

Electronic nicotine delivery systems (ENDS), or e-cigarettes, are emerging tobacco products that produce aerosols by heating e-liquids, which most often consist of propylene glycol and vegetable glycerin along with various flavoring compounds, bypassing the combustion that occurs in the use of traditional tobacco cigarettes. These products have seen a drastic increase in popularity in recent years both as smoking cessation devices as well as among younger generations, due in large part to the widespread perception among consumers that e-cigs are significantly less harmful to health than traditional tobacco cigarettes. Due to the novelty of ENDS as well as their rapidly increasing use, research into biomarkers of e-cig exposure and toxicity have lagged behind their popularity, leaving important questions about their potential toxicity unanswered. Research into potential biomarkers of acute and chronic e-cig use, and e-cigarette- or vaping-associated lung injury is necessary for informing both clinical and regulatory decision-making. We aim to provide an updated review of recent research into potential circulating, genomic, transcriptomic, and epigenetic biomarkers of exposure to and toxicity of e-cigs. We additionally highlight research areas that warrant additional study to gain a better understanding of health risks associated with ENDS use, as well as to provide validation of existing data and methods for measuring and analyzing e-cig-associated biomarkers in human and animal biofluids, tissues, and cells. This review also highlights ongoing efforts within the WNY Center for Research on Flavored Tobacco for research into novel biomarkers in extracellular vesicles that may be associated with short- and long-term ENDS use.

Comparison of the chemical composition of aerosols from heated tobacco products, electronic cigarettes and tobacco cigarettes and their toxic impacts on the human bronchial epithelial BEAS-2B cells

The electronic cigarettes (e-cigs) and more recently the heated tobacco products (HTP) provide alternatives for smokers as they are generally perceived to be less harmful than conventional cigarettes. However, it is crucial to compare the health risks of these different emergent devices, in order to determine which product should be preferred to substitute cigarette. The present study aimed to compare the composition of emissions from HTP, e-cigs and conventional cigarettes, regarding selected harmful or potentially harmful compounds, and their toxic impacts on the human bronchial epithelial BEAS-2B cells. The HTP emitted less polycyclic aromatic hydrocarbons and carbonyls than the conventional cigarette. However, amounts of these compounds in HTP aerosols were still higher than in e-cig vapours. Concordantly, HTP aerosol showed reduced cytotoxicity compared to cigarette smoke but higher than e-cig vapours. HTP and e-cig had the potential to increase oxidative stress and inflammatory response, in a manner similar to that of cigarette smoke, but after more intensive exposures. In addition, increasing e-cig power impacted levels of certain toxic compounds and related oxidative stress. This study provides important data necessary for risk assessment by demonstrating that HTP might be less harmful than tobacco cigarette but considerably more harmful than e-cig.

Addressing the challenges of E-cigarette safety profiling by assessment of pulmonary toxicological response in bronchial and alveolar mucosa models

Limited toxicity data on electronic cigarette (ECIG) impede evidence-based policy recommendations. We compared two popular mixed fruit flavored ECIG-liquids with and without nicotine aerosolized at 40 W (E-smoke) with respect to particle number concentrations, chemical composition, and response on physiologically relevant human bronchial and alveolar lung mucosa models cultured at air–liquid interface. E-smoke was characterized by significantly increased particle number concentrations with increased wattage (25, 40, and 55 W) and nicotine presence. The chemical composition of E-smoke differed across the two tested flavors in terms of cytotoxic compounds including p-benzoquinone, nicotyrine, and flavoring agents (for example vanillin, ethyl vanillin). Significant differences in the expression of markers for pro-inflammation, oxidative stress, tissue injury/repair, alarm anti-protease, anti-microbial defense, epithelial barrier function, and epigenetic modification were observed between the flavors, nicotine content, and/ or lung models (bronchial or alveolar). Our findings indicate that ECIG toxicity is influenced by combination of multiple factors including flavor, nicotine content, vaping regime, and the region of respiratory tree (bronchial or alveolar). Toxic chemicals and flavoring agents detected in high concentrations in the E-smoke of each flavor warrant independent evaluation for their specific role in imparting toxicity. Therefore, multi-disciplinary approaches are warranted for comprehensive safety profiling of ECIG.

Protein thiol oxidation in the rat lung following e-cigarette exposure

E-cigarette (e-cig) aerosols are complex mixtures of various chemicals including humectants (propylene glycol (PG) and vegetable glycerin (VG)), nicotine, and various flavoring additives. Emerging research is beginning to challenge the "relatively safe" perception of e-cigarettes. Recent studies suggest e-cig aerosols provoke oxidative stress; however, details of the underlying molecular mechanisms remain unclear. Here we used a redox proteomics assay of thiol total oxidation to identify signatures of site-specific protein thiol modifications in Sprague-Dawley rat lungs following in vivo e-cig aerosol exposures. Histologic evaluation of rat lungs exposed acutely to e-cig aerosols revealed mild perturbations in lung structure. Bronchoalveolar lavage (BAL) fluid analysis demonstrated no significant change in cell count or differential. Conversely, total lung glutathione decreased significantly in rats exposed to e-cig aerosol compared to air controls. Redox proteomics quantified the levels of total oxidation for 6682 cysteine sites representing 2865 proteins. Protein thiol oxidation and alterations by e-cig exposure induced perturbations of protein quality control, inflammatory responses and redox homeostasis. Perturbations of protein quality control were confirmed with semi-quantification of total lung polyubiquitination and 20S proteasome activity. Our study highlights the importance of redox control in the pulmonary response to e-cig exposure and the utility of thiol-based redox proteomics as a tool for elucidating the molecular mechanisms underlying this response.

People smoke for nicotine, but lose sexual and reproductive health for tar: a narrative review on the effect of cigarette smoking on male sexuality and reproduction

PURPOSE

To systematically review the impact of smoking habits on cardiovascular (CV) as well as on male sexual and reproductive function and to provide updated evidence on the role of electronic cigarettes (e-Cig) on the same topics.

METHODS

A comprehensive Medline, Embase, and Cochrane search was performed including the following words: smoking, CV system, CV risk, erectile dysfunction (ED), and male fertility. Publications from January 1, 1969 up to February 29, 2020 were included.

RESULTS

Smoking has a tremendous negative impact on CV mortality and morbidity. Current smoking behavior is also negatively associated with erectile dysfunction (ED) and impaired sperm parameters. E-Cig can release significantly lower concentrations of harmful substances when compared to regular combustible cigarettes. Whether or not the latter can result in positive CV, sexual, and fertility outcomes is still under study. Preliminary studies showed that exposure to e-Cig leads to lower vascular damage when compared to the traditional cigarette use. However, data on the long-term effects of e-Cig are lacking. Similarly, preliminary data, obtained in animal models, have suggested a milder effect of e-Cig on erectile function and sperm parameters.

CONCLUSION

Available evidence showed that e-Cig are much less dangerous when compared to the traditional tobacco use. However, it should be recognized that the risk related to e-Cig is still higher when compared to that observed in non-smoking patients. Hence, e-Cig should be considered as a potential tool, in the logic of harm reduction, to reduce the CV, sexual and fertility risk in patients refractory to the fundamental, healthy choice to definitively quit smoking.

[Pulmonary insufficiency in acute stroke: risk factors and mechanisms of development]

Various degrees of pulmonary insufficiency (PI) (PaO₂ ≤60 mm Hg, SaO₂ ≤90%) are diagnosed in most of patients with severe acute stroke (AS). Frequency and severity of PI positively correlates with the severity of AS. PI worsens patient's condition, prolongs the hospitalization period, and increases the probability of fatal outcome. Early clinical signs of PI may be undiagnosed due to the severity of stroke and thus not treated. The initiating pathogenic mechanism of PI is stress-related activation of sympathetic nervous system (SNS) and systemic immunosuppression. In severe stroke with mass effect, the rapid and significant increase in intracranial pressure may additionally activate the SNS. Risk factors of PI include older age, previous pulmonary disease, prolonged supine position, respiratory muscle dysfunction, apnea, and concomitant somatic diseases. Decompensation of somatic diseases leads to multiple stage reactions with facilitation of functional and morphologic changes in the pulmonary system, hypoxemia and hypoxia, promotes infectious complications and multiple organ failure and worsens neurological outcome. Diagnosis and treatment of PI in AS decreases mortality and improves rehabilitation prognosis.

Nicotine dependence as a risk factor for upper aerodigestive tract (UADT) cancers: A mediation analysis

PURPOSE

This study investigated nicotine dependence as an independent risk factor for upper aerodigestive tract (UADT) cancers, including lung and head and neck cancers (HNC). The study aimed to isolate the direct effect of nicotine dependence, independent of tobacco smoking.

METHODS

A case-control study with a total of 4957 participants was conducted in Ontario, Canada, of which 2964 categorized as either current or former smokers were used in the analysis. Nicotine dependence of ever-smokers (2360 UADT cases and 604 controls) was measured using the Fagerström Test for Nicotine Dependence. Using mediation analyses and adjusted logistic regression models, we decomposed the direct effect of nicotine dependence and the mediated effect of smoking duration to quantify the risks of lung and HNC. The role of human papillomavirus (HPV) and cancer subtypes were assessed.

RESULTS

Most individual nicotine dependence behaviours showed positive associations with lung cancer with approximately 1.8 to 3.5-fold risk increase, and to lesser extent with 1.4 to 2.3-fold risk for HNC. Nicotine dependence is partially accountable for increased risks of lung cancer (OR = 1.20, 95%CI = 1.13-1.28) and HNC (1.12, 95%CI = 1.04-1.19). Nicotine dependence had a greater effect on the risk of HPV-negative oropharyngeal cancer (OR = 3.06, 95%CI = 1.65-5.66) in comparison to HPV-positive oropharyngeal cancer (OR = 1.05, 95%CI = 0.67-1.65). The direct effects of nicotine dependence remained significant after accounting for cumulative tobacco exposures.

CONCLUSION

Nicotine dependence increases the risks of lung and HNC cancers after accounting for tobacco smoking, suggesting potential toxic effects of nicotine. These results are informative for the safety consideration of nicotine exposures.

Cardiovascular risk of electronic cigarettes: a review of preclinical and clinical studies

Cigarette smoking is the most preventable risk factor related to cardiovascular morbidity and mortality. Tobacco usage has declined in recent years; however, the use of alternative nicotine delivery methods, particularly e-cigarettes, has increased exponentially despite limited data on their short- and long-term safety and efficacy. Due to their unique properties, the impact of e-cigarettes on cardiovascular physiology is not fully known. Here, we summarize both preclinical and clinical data extracted from short- and long-term studies on the cardiovascular effects of e-cigarette use. Current findings support that e-cigarettes are not a harm-free alternative to tobacco smoke. However, the data are primarily derived from acute studies. The impact of chronic e-cigarette exposure is essentially unstudied. To explore the uniqueness of e-cigarettes, we contemplate the cardiovascular effects of individual e-cigarette constituents. Overall, data suggest that exposure to e-cigarettes could be a potential cardiovascular health concern. Further preclinical research and randomized trials are needed to expand basic and clinical investigations before considering e-cigarettes safe alternatives to conventional cigarettes.

Biological Toxicity of the Compositions in Electronic-Cigarette on Cardiovascular System

Using electronic cigarette (e-cig) among youth is becoming a critical public health crisis in the USA. However, the biological impacts of the e-cig on multiple organ systems, especially in the cardiovascular system, are largely unknown. Unlike conventional tobacco, e-cig combines various chemical ingredients including nicotine and other add-on non-nicotine chemicals, such as the solvents (propylene glycol and/or vegetable glycerin) and flavoring chemicals, which dramatically increases the diversity of the potential implications. The recent outbreak of e-cig vaping-related tragic deaths in youth and multiple hospitalized patients raised a question on the safety of e-cig use and led to an urgent need for the knowledge of the health risk of the e-cig compositions. Therefore, in the review, we summarized the latest findings from both human and animal studies on the potential cardiovascular toxicological effects of e-cig on the cardiovascular system in terms of the systemic physiological implications and the cellular and molecular mechanisms involved.

Health Hazards and Complications Associated with Electronic Cigarettes: A Review

Electronic cigarettes (ECs) are devices that vaporize and release a sweetened liquid containing nicotine as a substitute for burning tobacco. EC manufacturers have suggested that "vaping" is a safer alternative to conventional smoking because of the potential reduction of exposure to toxic substances. In 2019, National Youth Tobacco Survey reported that 10.5% and 27.5% of middle and high school students used ECs in the previous 30 days (0.6% and 1.5% in 2011, 3.3% and 11.7% in 2017, and 4.9% and 20.8 in 2018), respectively. Increased EC use among younger individuals is mainly because of the widespread perception that ECs are relatively less harmful than conventional cigarettes as they do not involve smoking tobacco and contain little or no nicotine. This review suggests that ECs may not be completely harmless. There are increasing number of case reports on various complications arising from using ECs, which are especially popular among young individuals and could negatively affect their health. Reported complications include lipoid pneumonia, acute eosinophilic pneumonia, hypersensitivity pneumonia, organizing pneumonia, diffuse alveolar hemorrhage, multiple reactive pulmonary nodules, subacute bronchiolitis, mouth and tongue injuries, dental injuries, complex facial fractures, thermal injuries, nickel contact allergy, C1 and C2 fractures, and fatal intoxication after ingesting liquids. Complications that develop directly from the substances in the devices and those resulting from device explosion and burning are being reported with increasing frequency. There is an urgent need for legislation and restriction regarding the sale of these devices considering their increasing frequency of use by younger individuals.

Smoke and Heart Should Stay Apart: A Look at E Cigarettes and Other Alternatives to Conventional Cigarettes, and Their Impact on Cardiovascular Health

The leading cause of preventable death in the world is smoking; leading to 7 million deaths attributable to tobacco use per year worldwide and 480,000 deaths per year in the United States. Though the actual rates of smoking in the United States have been on the decline, the advent of electronic cigarettes (E cigs) in 2007 was met with immense reception especially among the youth. Though initially thought to be a means to facilitate smoking cessation, recent evidence and the E cigs epidemic suggest its implications in significant morbidity and mortality. The other alternatives for conventional tobacco cigarettes have also been implicated in cardiovascular diseases. This manuscript aims to review E cigarettes and other alternatives to conventional cigarettes, and their impact on cardiovascular health. We conducted a Medline search using various combinations of "Cigarettes," "E cigarettes," "Smokeless tobacco," "hookah", and "cardiovascular risk" to identify pivotal trials published before May 10, 2020, for inclusion in this review. Concurrently, major practice guidelines, trial bibliographies, and pertinent reviews were examined to ensure inclusion of relevant trials. A consensus among the authors was used to choose items for narrative inclusion. The following section reviews data from pivotal trials to review the effects of E cigarettes, smokeless tobacco, hookah, nicotine replacement therapy on cardiovascular mortality and morbidity. There are many alternatives to conventional tobacco cigarette smoking, but none can be attributed as absolutely safe from a cardiovascular health perspective. The abundance of evidence regarding its impact on cardiovascular mortality and morbidity does not position it as a safe alternative, but an alternative means of smoking nicotine. The humongous rise in popularity and its gain in favor among the younger population poses a serious threat to the cardiovascular well-being of the exposed. Thus, E cigs and other alternatives of cigarette smoking do impart differing risks in cardiovascular mortality and morbidity, with the possible exception of nicotine replacement therapy.

Vaping-Related Acute Parenchymal Lung Injury: A Systematic Review

The outbreak of vaping-related acute lung injury in the United States, named EVALI (e-cigarette or vaping product use associated acute lung injury), has reignited concerns about the health effects of vaping. Initial case reports of vaping-related lung injury date back to 2012, but the ongoing outbreak of EVALI began in the summer of 2019 and has been implicated in 2,807 cases and 68 deaths as of this writing. Review of the scientific literature revealed 216 patient cases that spanned 41 reports of parenchymal lung injury attributed to vaping. In this review, we detail the clinical, radiographic, and pathologic patterns of lung injury that are attributable to vaping and provide an overview of the scientific literature to date on the effects of vaping on respiratory health. Tetrahydrocannabinol was the most commonly vaped substance, and vitamin E acetate was found in BAL specimens from many affected individuals. However, no specific component or contaminant has been identified conclusively to date as the cause for the injury. Patients present with cough, dyspnea, constitutional symptoms, and GI symptoms. Radiologic and histopathologic findings demonstrate a spectrum of nonspecific acute injury patterns. A high index of suspicion combined with a good history are the keys to an accurate diagnosis. Treatment is supportive; the mortality rate is low, and most patients recover. Corticosteroids have been used with apparent success in patients with severe disease, but more rigorous studies are needed to clarify their role in the treatment of vaping-related lung injury.