The Effect of Flavored E-cigarettes on Murine Allergic Airways Disease

[Harmful health effects of flavors in e-cigarettes]

BACKGROUND

Almost all e-cigarettes contain flavorings that make the product more attractive. In the evaluation of e-cigarettes on health, flavors have so far played a subordinate role.

METHOD

Selective literature search in PubMed, supplemented by legal regulations on the use of flavors in e-cigarettes.

RESULTS

Flavors make it easier to start using e-cigarettes and have a consumption-promoting effect. Deeper inhalation increases nicotine uptake and the absorption of toxic substances from the e-cigarette liquid. For some flavors, pathological effects have been demonstrated in addition to other toxic components of the e-cigarette. To date, no toxicological analyses are available for the vast majority of flavors contained in e-cigarettes.

CONCLUSIONS

The proven consumption-promoting effect and the health risks that can be extrapolated from preclinical data are significant for the political discussion of a ban on flavors for e-cigarettes, analogous to the ban on flavors in tobacco products already in force.

Respiratory Symptoms among Adolescents in Poland: A Study on Cigarette Smokers, E-Cigarette Users, and Dual Users

In recent years, the prevalence of tobacco and electronic cigarette (e-cigarette) use among adolescents has raised significant public health concerns worldwide. This study aimed to investigate respiratory symptoms among Polish adolescents. We conducted an online survey among Polish school students from all provinces, collecting data over two months in spring 2021. Students voluntarily complete the anonymous survey, answering questions about respiratory symptoms, smoking habits (both traditional and electronic cigarettes), and demographic information. The analysis focused on four subgroups, namely non-tobacco users, traditional cigarette smokers, e-cigarette users, and dual users, totaling 10,388 pupils aged 12-18 years, predominantly attending secondary technical and comprehensive schools. A total of 10,388 pupils participated in the study, 55.6% (5778) of whom were girls and 44.4% (4610) boys. Adolescents who admitted using both e-cigarettes and traditional cigarettes experienced more frequent episodes of cough during the day (39.70%) and at night (18.40%) compared to their peers in other groups. Chest discomfort, including pain and pressure, was also reported more often by adolescents who used e-cigarettes and traditional cigarettes concurrently (27.60%) compared to their peers in other groups. Chest pressure was experienced less commonly by non-smoking adolescents (14.40%) than by smokers (18.90%). Higher severity of cough during the day and at night was observed in the group of adolescents using traditional cigarettes and e-cigarettes concurrently compared to the other groups. The adolescents in the dual-user group experienced more severe dyspnea and wheezing compared to the other groups included in the comparison. The results of this study confirm the correlation between the occurrence of respiratory symptoms in adolescents who smoke cigarettes, adolescents who use e-cigarettes, and adolescents who are dual users. The respiratory symptoms occur most frequently and are the most severe in the group of adolescents who use e-cigarettes and traditional cigarettes.

The paradox of the safer cigarette: understanding the pulmonary effects of electronic cigarettes

Electronic cigarette (e-cigarette) use continues to rise globally. E-cigarettes have been presented as safer alternatives to combustion cigarettes that can mitigate the harm associated with tobacco products; however, the degree to which e-cigarette use itself can lead to morbidity and mortality is not fully defined. Herein we describe how e-cigarettes function; discuss the current knowledge of the effects of e-cigarette aerosol on lung cell cytotoxicity, inflammation, antipathogen immune response, mucociliary clearance, oxidative stress, DNA damage, carcinogenesis, matrix remodelling and airway hyperresponsiveness; and summarise the impact on lung diseases, including COPD, respiratory infection, lung cancer and asthma. We highlight how the inclusion of nicotine or flavouring compounds in e-liquids can impact lung toxicity. Finally, we consider the paradox of the safer cigarette: the toxicities of e-cigarettes that can mitigate their potential to serve as a harm reduction tool in the fight against traditional cigarettes, and we summarise the research needed in this underinvestigated area.

[Harmful health effects of flavors in e-cigarettes]

BACKGROUND

 Almost all e-cigarettes contain flavorings that make the product more attractive. In the evaluation of e-cigarettes on health, flavors have so far played a subordinate role.

METHOD

 Selective literature search in PubMed, supplemented by legal regulations on the use of flavors in e-cigarettes.

RESULTS

 Flavors make it easier to start using e-cigarettes and have a consumption-promoting effect. Deeper inhalation increases nicotine uptake and the absorption of toxic substances from the e-cigarette liquid. For some flavors, pathological effects have been demonstrated in addition to other toxic components of the e-cigarette. To date, no toxicological analyses are available for the vast majority of flavors contained in e-cigarettes.

CONCLUSIONS

 The proven consumption-promoting effect and the health risks that can be extrapolated from preclinical data are significant for the political discussion of a ban on flavors for e-cigarettes, analogous to the ban on flavors in tobacco products already in force.

[Medical societies in Germany call for a ban on flavors in e-cigarettes - A Position Paper of the German Respiratory Society (DGP) in cooperation with other professional associations and organizations]

E-cigarettes are primarily used by teenagers and young adults. Flavors in e-cigarettes increase their attractiveness and encourage young people and adults to start using them. This exposes young people in particular to the risk of nicotine addiction and various toxic substances from the aerosol of e-cigarettes. There are indications that various flavors in e-cigarettes are harmful to health, although toxicological studies are still lacking for the majority of flavors. There is a need for independent scientific investigations in this area. The scientific societies involved are calling for a ban on flavors in e-cigarettes, a ban on disposable e-cigarettes, effective regulation of the sale of e-cigarettes and effective control and implementation of the provisions for the protection of minors.

Tobacco-derived and tobacco-free nicotine cause differential inflammatory cell influx and MMP-9 in mouse lung

BACKGROUND

Electronic nicotine delivery systems (ENDS) or electronic cigarettes (e-cigarettes) aerosolize an e-liquid composed of propylene glycol (PG) and vegetable glycerin (VG) as humectants, flavoring chemicals, and nicotine. Nicotine naturally occurs in two isomers R- and S-nicotine, with tobacco-derived nicotine (TDN) composed of S-nicotine, and tobacco-free/synthetic nicotine (TFN) composed of a racemic mixture of R- and S-nicotine. Currently, there is limited knowledge of the potential differences in the toxicity of TFN versus TDN. We hypothesized that exposure of TFN and TDN salts to C57BL/6J mice would result in a differential response in lung inflammation and protease/ antiprotease imbalance.

METHODS

Five-week-old male and female C57BL/6J mice were exposed to air, PG/VG, PG/VG with TFN salts (TFN), or PG/VG with TDN salts (TDN) by nose-only exposure. Lung inflammatory cell counts, cytokine/chemokine levels, and matrix metalloproteinase (MMP) protein abundance and activity levels were determined by flow cytometry, ELISA, immunoblotting, and gel zymography, respectively.

RESULTS

Exposure to the humectants (PG/VG) alone increased cytokine levels- IL-6, KC, and MCP-1 in the BALF and KC levels in lung homogenate of exposed mice. While no change was observed in the cytokine levels in lung homogenate of TDN aerosol exposed mice, exposure to TFN aerosols resulted in an increase in KC levels in the lungs of these mice compared to air controls. Interestingly, exposure to TDN aerosols increased MMP-9 protein abundance in the lungs of female mice, while exposure to TFN aerosol showed no change. The metabolism of nicotine or the clearance of cotinine for TFN exposure may differ from that for TDN.

CONCLUSION

Exposure to humectants, PG/VG alone, induces an inflammatory response in C57BL/6J mice. TFN and TDN salts show distinct changes in inflammatory responses and lung proteases on acute exposures. These data suggest variable toxicological profiles of the two forms of nicotine in vivo. Future work is thus warranted to delineate the harmful effects of synthetic/natural nicotine with humectants to determine the potential toxicological risks for users.

Tobacco-Derived and Tobacco-Free Nicotine cause differential inflammatory cell influx and MMP9 in mouse lung

Electronic nicotine delivery systems (ENDS) or electronic cigarettes (e-cigarettes) have propylene glycol (PG) and vegetable glycerin (VG) as humectants, flavoring chemicals, and nicotine. Nicotine naturally occurs in two isomers R- and S-nicotine, with both tobacco-derived nicotine (TDN) composed of S-nicotine and synthetic nicotine (TFN) composed of a racemic mixture of R- and S-nicotine. Currently there is limited knowledge of the potential differences in the toxicity of TFN vs TDN. We hypothesized that exposure of TFN salts to C57BL/6J mice will result in a differential response in inflammation and lung protease and antiprotease imbalance compared to TDN salts exposed mice. We studied the toxicological impact of these isomers by exposing mice to air, PG/VG, PG/VG with TFN salts, or PG/VG with TDN salts by nose-only exposure and measured the cytokine levels in BALF and lung homogenate along with MMP protein abundance in the lungs of exposed mice. Exposure to the humectants, PG/VG, used in e-cigarettes alone was able to increase cytokine levels-IL-6, KC, and MCP-1 in BALF and KC levels in lung homogenate. Further, it showed differential responses on exposure to PG/VG with TDN salts and PG/VG with TFN salts since PG/VG with TDN salts did not alter the cytokine levels in lung homogenate while PG/VG with TFN salts resulted in an increase in KC levels. PG/VG with TDN salts increased the levels of MMP9 protein abundance in female exposed mice, while PG/VG with TFN salts did not alter MMP9 levels in female mice. The metabolism of nicotine or the clearance of cotinine from TFN may differ from the metabolism of nicotine or the clearance of cotinine from TDN. Thus exposure of humectants alone to induce an inflammatory response while PG/VG with TFN salts and PG/VG with TDN salts may differentially alter inflammatory responses and lung proteases in acute exposures. These data suggest the harmful effects of synthetic/natural nicotine and PG/VG and potential toxicological risk for users.

Long-Term Impact of Daily E-cigarette Exposure on the Lungs of Asthmatic Mice

INTRODUCTION

Although the greater popularity of electronic cigarettes (EC) among asthmatics is alarming, there is limited knowledge of the long-term consequences of EC exposure in asthmatics.

AIMS AND METHODS

Mild asthmatic C57/BL6J adult male and female mice were established by intranasal insufflation with three combined allergens. The asthmatic and age and sex-matched' naïve mice were exposed to air, nicotine-free (propylene glycol [PG]/vegetable glycerin [VG]-only), or PG/VG+Nicotine, 4 hours daily for 3 months. The effects of EC exposure were accessed by measuring cytokines in bronchoalveolar lavage, periodic acid-schiff (PAS) staining, mitochondrial DNA copy numbers (mtCN), and the transcriptome in the lung. Significance was false discovery rate <0.2 for transcriptome and 0.05 for the others.

RESULTS

In asthmatic mice, PG/VG+Nicotine increased PAS-positive cells and IL-13 compared to mice exposed to air and PG/VG-only. In naïve mice exposed to PG/VG+Nicotine and PG/VG-only, higher INF-γ was observed compared to mice exposed only to air. PG/VG-only and PG/VG+Nicotine had significantly higher mtCN compared to air exposure in asthmatic mice, while the opposite pattern was observed in non-asthmatic naïve mice. Different gene expression patterns were profoundly found for asthmatic mice exposed to PG/VG+Nicotine compared to PG/VG-only, including genes involved in mitochondrial dysfunction, oxidative phosphorylation, and p21-activated kinase (PAK) signaling.

CONCLUSIONS

This study provides experimental evidence of the potential impact of nicotine enhancement on the long-term effects of EC in asthmatics compared to non-asthmatics.

IMPLICATIONS

The findings from this study indicate the potential impact of EC in asthmatics by addressing multiple biological markers. The long-term health outcomes of EC in the susceptible group can be instrumental in supporting policymaking and educational campaigns and informing the public, healthcare providers, and EC users about the underlying risks of EC use.

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.

Cardiopulmonary Impact of Electronic Cigarettes and Vaping Products: A Scientific Statement From the American Heart Association

Vaping and electronic cigarette (e-cigarette) use have grown exponentially in the past decade, particularly among youth and young adults. Cigarette smoking is a risk factor for both cardiovascular and pulmonary disease. Because of their more limited ingredients and the absence of combustion, e-cigarettes and vaping products are often touted as safer alternative and potential tobacco-cessation products. The outbreak of e-cigarette or vaping product use-associated lung injury in the United States in 2019, which led to >2800 hospitalizations, highlighted the risks of e-cigarettes and vaping products. Currently, all e-cigarettes are regulated as tobacco products and thus do not undergo the premarket animal and human safety studies required of a drug product or medical device. Because youth prevalence of e-cigarette and vaping product use was as high as 27.5% in high school students in 2019 in the United States, it is critical to assess the short-term and long-term health effects of these products, as well as the development of interventional and public health efforts to reduce youth use. The objectives of this scientific statement are (1) to describe and discuss e-cigarettes and vaping products use patterns among youth and adults; (2) to identify harmful and potentially harmful constituents in vaping aerosols; (3) to critically assess the molecular, animal, and clinical evidence on the acute and chronic cardiovascular and pulmonary risks of e-cigarette and vaping products use; (4) to describe the current evidence of e-cigarettes and vaping products as potential tobacco-cessation products; and (5) to summarize current public health and regulatory efforts of e-cigarettes and vaping products. It is timely, therefore, to review the short-term and especially the long-term implications of e-cigarettes and vaping products on cardiopulmonary health. Early molecular and clinical evidence suggests various acute physiological effects from electronic nicotine delivery systems, particularly those containing nicotine. Additional clinical and animal-exposure model research is critically needed as the use of these products continues to grow.

Human matters in asthma: Considering the microbiome in pulmonary health

Microbial communities form an important symbiotic ecosystem within humans and have direct effects on health and well-being. Numerous exogenous factors including airborne triggers, diet, and drugs impact these established, but fragile communities across the human lifespan. Crosstalk between the mucosal microbiota and the immune system as well as the gut-lung axis have direct correlations to immune bias that may promote chronic diseases like asthma. Asthma initiation and pathogenesis are multifaceted and complex with input from genetic, epigenetic, and environmental components. In this review, we summarize and discuss the role of the airway microbiome in asthma, and how the environment, diet and therapeutics impact this low biomass community of microorganisms. We also focus this review on the pediatric and Black populations as high-risk groups requiring special attention, emphasizing that the whole patient must be considered during treatment. Although new culture-independent techniques have been developed and are more accessible to researchers, the exact contribution the airway microbiome makes in asthma pathogenesis is not well understood. Understanding how the airway microbiome, as a living entity in the respiratory tract, participates in lung immunity during the development and progression of asthma may lead to critical new treatments for asthma, including population-targeted interventions, or even more effective administration of currently available therapeutics.

Pulmonary effects of e-liquid flavors: a systematic review

Electronic cigarettes (ECs) are purported to be tobacco harm-reduction products whose degree of harm has been highly debated. EC use is considered less hazardous than smoking but is not expected to be harmless. Following the banning of e-liquid flavors in countries such as the US, Finland, Ukraine, and Hungary, there are growing concerns regarding the safety profile of e-liquid flavors used in ECs. While these are employed extensively in the food industry and are generally regarded as safe (GRAS) when ingested, GRAS status after inhalation is unclear. The aim of this review was to assess evidence from 38 reports on the adverse effects of flavored e-liquids on the respiratory system in both in vitro and in vivo studies published between 2006 and 2021. Data collected demonstrated greater detrimental effects in vitro with cinnamon (9 articles), strawberry (5 articles), and menthol (10 articles), flavors than other flavors. The most reported effects among these investigations were perturbations of pro-inflammatory biomarkers and enhanced cytotoxicity. There is sufficient evidence to support the toxicological impacts of diacetyl- and cinnamaldehyde-containing e-liquids following human inhalation; however, safety profiles on other flavors are elusive. The latter may result from inconsistencies between experimental approaches and uncertainties due to the contributions from other e-liquid constituents. Further, the relevance of the concentration ranges to human exposure levels is uncertain. Evidence indicates that an adequately controlled and consistent, systematic toxicological investigation of a broad spectrum of e-liquid flavors may be required at biologically relevant concentrations to better inform public health authorities on the risk assessment following exposure to EC flavor ingredients.

On the toxicity of e-cigarettes consumption: Focus on pathological cellular mechanisms

Tobacco smoking remains without a doubt one of the leading causes of premature death worldwide. In combination with conventional protocols for smoking cessation, e-cigarettes have been proposed as a useful tool to quit smoking. Advertised as almost free of toxic effects, e-cigarettes have rapidly increased their popularity, becoming a sought-after device, especially among young people. Recently some health concerns about e-cigarette consumption are being raised. It is well known that they can release several toxic compounds, some of which are carcinogenic to humans, and emerging results are now outlining the risks related to the onset of respiratory and cardiovascular diseases and even cancer. The present review shows the emerging evidence about the role of technical components of the devices, the e-liquid composition as well as customization by consumers. The primary topics we discuss are the main toxicological aspects associated with e-cigarette consumption, focusing on the molecular pathways involved. Here it will be shown how exposure to e-cigarette aerosol induces stress/mitochondrial toxicity, DNA breaks/fragmentation following the same pathological pathways triggered by tobacco smoke, including the deregulation of molecular signalling axis associated with cancer progression and cell migration. Risk to fertility and pregnancy, as well as cardiovascular risk associated with e-cigarette use, have also been reported.

MRI Shows Lung Perfusion Changes after Vaping and Smoking

Background Evidence regarding short-term effects of electronic nicotine delivery systems (ENDS) and tobacco smoke on lung ventilation and perfusion is limited. Purpose To examine the immediate effect of ENDS exposure and tobacco smoke on lung ventilation and perfusion by functional MRI and lung function tests. Materials and Methods This prospective observational pilot study was conducted from November 2019 to September 2021 (substudy of randomized controlled trial NCT03589989). Included were 44 healthy adult participants (10 control participants, nine former tobacco smokers, 13 ENDS users, and 12 active tobacco smokers; mean age, 41 years ± 12 [SD]; 28 men) who underwent noncontrast-enhanced matrix pencil MRI and lung function tests before and immediately after the exposure to ENDS products or tobacco smoke. Baseline measurements were acquired after 2 hours of substance abstinence. Postexposure measurements were performed immediately after the exposure. MRI showed semiquantitative measured impairment of lung perfusion (R_Q) and fractional ventilation (R_FV) impairment as percentages of affected lung volume. Lung clearance index (LCI) was assessed by nitrogen multiple-breath washout to capture ventilation inhomogeneity and spirometry to assess airflow limitation. Absolute differences were calculated with paired Wilcoxon signed-rank test and differences between groups with unpaired Mann-Whitney test. Healthy control participants underwent two consecutive MRI measurements to assess MRI reproducibility. Results MRI was performed and lung function measurement was acquired in tobacco smokers and ENDS users before and after exposure. MRI showed a decrease of perfusion after exposure (R_Q, 8.6% [IQR, 7.2%-10.0%] to 9.1% [IQR, 7.8%-10.7%]; P = .03) and no systematic change in R_FV (P = .31) among tobacco smokers. Perfusion increased in participants who used ENDS after exposure (R_Q, 9.7% [IQR, 7.1%-10.9%] to 9.0% [IQR, 6.9%-10.0%]; P = .01). R_FV did not change (P = .38). Only in tobacco smokers was LCI elevated after smoking (P = .02). Spirometry indexes did not change in any participants. Conclusion MRI showed a decrease of lung perfusion after exposure to tobacco smoke and an increase of lung perfusion after use of electronic nicotine delivery systems. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Kligerman in this issue.

Vaping in Asthmatic Adolescents: Time to Deal with the Elephant in the Room

Adolescence is a period characterized by developmental, psychological, and psychosocial alterations, with a major impact on youths’ attitudes and perceptions. Adolescents with asthma may not comply with treatment and may develop risky behaviors, including smoking, vaping, and other substance use, leading to unanticipated exacerbations and consequences. Vaping has become extremely popular in this age group, and studies have suggested that it has potential adverse effects on asthmatic airways. More well-designed studies are needed to confirm the initial worrying data, and action must be taken by both medical officers and health authorities to deal with the elephant in the room and curb the vaping pandemic. The aim of this paper is to provide a review of the current knowledge regarding the effect of vaping on adolescents with asthma and to propose actions to restrain this fast-growing trend.

Vaping and Lung Inflammation and Injury

The use of electronic (e)-cigarettes was initially considered a beneficial solution to conventional cigarette smoking cessation. However, paradoxically, e-cigarette use is rapidly growing among nonsmokers, including youth and young adults. In 2019, this rapid growth resulted in an epidemic of hospitalizations and deaths of e-cigarette users (vapers) due to acute lung injury; this novel disease was termed e-cigarette or vaping use-associated lung injury (EVALI). Pathophysiologic mechanisms of EVALI likely involve cytotoxicity and neutrophilic inflammation caused by inhaled chemicals, but further details remain unknown. The undiscovered mechanisms of EVALI are a barrier to identifying biomarkers and developing therapeutics. Furthermore, adverse effects of e-cigarette use have been linked to chronic lung diseases and systemic effects on multiple organs. In this comprehensive review, we discuss the diverse spectrum of vaping exposures, epidemiological and clinical reports, and experimental findings to provide a better understanding of EVALI and the adverse health effects of chronic e-cigarette exposure.

E-Cigarette Toxicology

Since the spread of tobacco from the Americas hundreds of years ago, tobacco cigarettes and, more recently, alternative tobacco products have become global products of nicotine addiction. Within the evolving alternative tobacco product space, electronic cigarette (e-cigarette) vaping has surpassed conventional cigarette smoking among adolescents and young adults in the United States and beyond. This review describes the experimental and clinical evidence of e-cigarette toxicity and deleterious health effects. Adverse health effects related to e-cigarette aerosols are influenced by several factors, including e-liquid components, physical device factors, chemical changes related to heating, and health of the e-cigarette user (e.g., asthmatic). Federal, state, and local regulations have attempted to govern e-cigarette flavors, manufacturing, distribution, and availability, particularly to underaged youths. However, the evolving e-cigarette landscape continues to impede timely toxicological studies and hinder progress made toward our understanding of the long-term health consequence of e-cigarettes.

The chemistry and toxicology of vaping

Vaping is the process of inhaling and exhaling an aerosol produced by an e-cigarette, vape pen, or personal aerosolizer. When the device contains nicotine, the Food and Drug Administration (FDA) lists the product as an electronic nicotine delivery system or ENDS device. Similar electronic devices can be used to vape cannabis extracts. Over the past decade, the vaping market has increased exponentially, raising health concerns over the number of people exposed and a nationwide outbreak of cases of severe, sometimes fatal, lung dysfunction that arose suddenly in otherwise healthy individuals. In this review, we discuss the various vaping technologies, which are remarkably diverse, and summarize the use prevalence in the U.S. over time by youths and adults. We examine the complex chemistry of vape carrier solvents, flavoring chemicals, and transformation products. We review the health effects from epidemiological and laboratory studies and, finally, discuss the proposed mechanisms underlying some of these health effects. We conclude that since much of the research in this area is recent and vaping technologies are dynamic, our understanding of the health effects is insufficient. With the rapid growth of ENDS use, consumers and regulatory bodies need a better understanding of constituent-dependent toxicity to guide product use and regulatory decisions.

Acute and chronic effects of vaping electronic devices on lung physiology and inflammation

The impact of e-cigarette use on the inflammatory state and function of the lungs is not well understood. Here we review the latest studies on the impact of short and long term e-cigarette aerosol inhalation on molecular pathways, cellular recruitment, gas exchange and airway physiology. Inflammatory cytokines IL-6 and IL-8 were increased by e-cigarette exposures, and a variety of immune cells were recruited to the parenchyma and airways across models. While there are few consistent signals across in vitro, in vivo and human studies, due to the multitude of different e-devices and the combination of chemicals within different aerosols generated, it is clear that use of e-cigarettes does alter the inflammatory state and function of the lungs with both acute and chronic use. This is evidenced by the multitude of inflammatory lung diseases already tied to e-cigarette use, but the causal chemicals are primarily remain at large.

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.

Electronic Cigarettes and Asthma: What Do We Know So Far?

Electronic cigarettes (EC) are a novel product, marketed as an alternative to tobacco cigarette. Its effects on human health have not been investigated widely yet, especially in specific populations such as patients with asthma. With this review, we use the existing literature in order to answer four crucial questions concerning: (1) ECs' role in the pathogenesis of asthma; (2) ECs' effects on lung function and airway inflammation in patients with asthma; (3) ECs' effects on asthma clinical characteristics in asthmatics who use it regularly; and (4) ECs' effectiveness as a smoking cessation tool in these patients. Evidence suggests that many EC compounds might contribute to the pathogenesis of asthma. Lung function seems to deteriorate by the use of EC in this population, while airway inflammation alters, with the aggravation of T-helper-type-2 (Th2) inflammation being the most prominent but not the exclusive effect. EC also seems to worsen asthma symptoms and the rate and severity of exacerbations in asthmatics who are current vapers, whilst evidence suggests that its effectiveness as a smoking cessation tool might be limited. Asthmatic patients should avoid using EC.

Experimenting first with e-cigarettes versus first with cigarettes and transition to daily cigarette use among adolescents: the crucial effect of age at first experiment

BACKGROUND AND AIMS

Most studies in English-speaking countries have found a positive association between e-cigarette experimentation and subsequent daily tobacco smoking among adolescents. However, this result may not be valid in other cultural contexts; in addition, few studies have assessed whether this association varies with the subject' age at the time of e-cigarette experimentation. This study aimed to estimate the association between experimenting first with e-cigarette (rather than tobacco) and subsequent daily smoking according to age at the time of experimentation.

DESIGN

Secondary analysis; risk ratios (RRs) computed using modified Poisson regressions with inverse probability weighting.

SETTING

A cross-sectional nation-wide representative survey performed in 2017 in France.

PARTICIPANTS

French adolescents (n = 24 111), aged 17 to 18.5 years, who had previously experimented with either e-cigarettes or tobacco.

MEASURES

Exposure was defined as the experimentation with e-cigarettes first (whether or not followed by experimentation with tobacco); the outcome as daily tobacco smoking at the time of data collection. Gender, age, literacy, socio-economic status, pre-exposure repeat school years and experimentation with drunkeness, 3 licit and 8 illicit drugs were adjusted for. Uncertainties about the sequence of events defining exposure were handled by the definition of three patterns of exposure, to avoid a misclassification bias.

FINDINGS

Exposure reduced the risk of transition to daily smoking: RR = 0.58, 95% confidence interval (CI) = 0.54, 0.62. This effect increased in a linear manner with age at exposure (RR = 0.87, 95% CI = 0.78; 0.98 for 1 year, P < 0.001): from RR = 1.30, 95% CI = 1.09; 1.54 at age 9 to RR = 0.38, 95% CI = 0.32; 0.45 at age 17.

CONCLUSIONS

Experimenting with e-cigarettes first (as opposed to tobacco first) appears to be associated with a reduction in the risk of daily tobacco smoking among French adolescents aged 17-18.5, but this risk varies negatively with age at experimentation, and early e-cigarette experimenters are at higher risk.

Understanding potential mechanisms of harm: the drivers of electronic cigarette-induced changes in alveolar macrophages, neutrophils, and lung epithelial cells

Electronic (e-) cigarettes are growing in popularity despite uncertainties regarding their long-term health implications. The link between cigarette smoking and initiation of chronic lung disease took decades to unpick so in vitro studies mimicking e-cigarette exposure aim to detect early indicators of harm. In response to e-cigarette exposure, alveolar macrophages adopt a proinflammatory phenotype of increased secretion of proinflammatory cytokines, reduction in phagocytosis, and efferocytosis and reactive oxygen species generation. These effects are largely driven by free radical exposure, changes in PI3K/Akt signaling pathways, nicotine-induced reduction in phagocytosis receptors, and impaired lipid homeostasis leading to a foam-like lipid-laden phenotype. Neutrophils exhibit disrupted chemotaxis and transmigration to chemokines, reduced phagocytosis and bacterial killing, and an increase in protease secretion without corresponding antiproteases in response to e-cigarette exposure. This is driven by an altered ability to respond and to polarize toward chemoattractants, an activation of the p38 MAPK signaling pathway and inability to assemble NADPH oxidase. E-cigarettes induce lung epithelial cells to display decreased ciliary beat frequency and ion channel conductance as well as changes in chemokine secretion and surface protein expression. Changes in gene expression, mitochondrial function, and signaling pathways have been demonstrated in lung epithelial cells to explain these changes. Many functional outputs of alveolar macrophages, neutrophils, and lung epithelial cells have not been fully explored in the context of e-cigarette exposure and the underlying driving mechanisms are poorly understood. This review discusses current evidence surrounding the effects of e-cigarettes on alveolar macrophages, neutrophils, and lung epithelial cells with particular focus on the cellular mechanisms of change.

Toxicology of flavoring- and cannabis-containing e-liquids used in electronic delivery systems

Electronic cigarettes (e-cigarettes) were introduced in the United States in 2007 and by 2014 they were the most popular tobacco product amongst youth and had overtaken use of regular tobacco cigarettes. E-cigarettes are used to aerosolize a liquid (e-liquid) that the user inhales. Flavorings in e-liquids is a primary reason for youth to initiate use of e-cigarettes. Evidence is growing in the scientific literature that inhalation of some flavorings is not without risk of harm. In this review, 67 original articles (primarily cellular in vitro) on the toxicity of flavored e-liquids were identified in the PubMed and Scopus databases and evaluated critically. At least 65 individual flavoring ingredients in e-liquids or aerosols from e-cigarettes induced toxicity in the respiratory tract, cardiovascular and circulatory systems, skeletal system, and skin. Cinnamaldehyde was most frequently reported to be cytotoxic, followed by vanillin, menthol, ethyl maltol, ethyl vanillin, benzaldehyde and linalool. Additionally, modern e-cigarettes can be modified to aerosolize cannabis as dried plant material or a concentrated extract. The U.S. experienced an outbreak of lung injuries, termed e-cigarette, or vaping, product use-associated lung injury (EVALI) that began in 2019; among 2,022 hospitalized patients who had data on substance use (as of January 14, 2020), 82% reported using a delta-9-tetrahydrocannabinol (main psychoactive component in cannabis) containing e-cigarette, or vaping, product. Our literature search identified 33 articles related to EVALI. Vitamin E acetate, a diluent and thickening agent in cannabis-based products, was strongly linked to the EVALI outbreak in epidemiologic and laboratory studies; however, e-liquid chemistry is highly complex, and more than one mechanism of lung injury, ingredient, or thermal breakdown product may be responsible for toxicity. More research is needed, particularly with regard to e-cigarettes (generation, power settings, etc.), e-liquids (composition, bulk or vaped form), modeled systems (cell type, culture type, and dosimetry metrics), biological monitoring, secondhand exposures and contact with residues that contain nicotine and flavorings, and causative agents and mechanisms of EVALI toxicity.

A machine learning approach to identify correlates of current e-cigarette use in Canada

Aim: Popularity of electronic cigarettes (i.e. e-cigarettes) is soaring in Canada. Understanding person-level correlates of current e-cigarette use (vaping) is crucial to guide tobacco policy, but prior studies have not fully identified these correlates due to model overfitting caused by multicollinearity. This study addressed this issue by using classification tree, a machine learning algorithm. Methods: This population-based cross-sectional study used the Canadian Tobacco, Alcohol, and Drugs Survey (CTADS) from 2017 that targeted residents aged 15 or older. Forty-six person-level characteristics were first screened in a logistic mixed-effects regression procedure for their strength in predicting vaper type (current vs. former vaper) among people who reported to have ever vaped. A 9:1 ratio was used to randomly split the data into a training set and a validation set. A classification tree model was developed using the cross-validation method on the training set using the selected predictors and assessed on the validation set using sensitivity, specificity and accuracy. Results: Of the 3,059 people with an experience of vaping, the average age was 24.4 years (standard deviation = 11.0), with 41.9% of them being female and 8.5% of them being aboriginal. There were 556 (18.2%) current vapers. The classification tree model performed relatively well and suggested attraction to e-cigarette flavors was the most important correlate of current vaping, followed by young age (< 18) and believing vaping to be less harmful to oneself than cigarette smoking. Conclusions: People who vape due to flavors are associated with very high risk of becoming current vapers. The findings of this study provide evidence that supports the ongoing ban on flavored vaping products in the US and suggests a similar regulatory intervention may be effective in Canada.

How harmless are E-cigarettes? Effects in the pulmonary system

PURPOSE OF REVIEW

Electronic cigarettes have quickly risen to be the leading alternative nicotine source to tobacco. E-cigarette use is hard to research and regulate because of the novelty and rapid evolution of the devices and E-liquids. Epidemiological data on long-term usage is currently lacking, but in smaller cohort studies we are starting to understand the usage patterns and demographics of users, which differ depending on where the study takes place and the regulatory environment. The present review describes the current knowledge of the effects of E-cigarettes on the pulmonary system and knowledge of their usage patterns worldwide.

RECENT FINDINGS

E-cigarette use is continuing to rise in young adults in United States and Canada, but not in United Kingdom. These suggest that regulation is influencing uptake in young adults. If E-cigarettes are to be considered as a harm minimisation smoking cessation product, use in young never smokers must be factored into the risk assessment. A recent surge in cases of lung injury associated with vaping in America has resulted in the definition of vaping associated pulmonary injury, although the exact cause remains unknown.

SUMMARY

It is our opinion that E-cigarettes can no longer be defined as harmless. Further studies are needed to determine the risks for all populations as it is evident that a large proportion of E-cigarette users are never-smokers, meaning they cannot only be considered from a harm reduction perspective.

Nicotine in E-Cigarettes Dysregulates Pulmonary Inflammation and MMP-12 Expression without Effecting Respiratory Syncytial Virus Virulence

The safety of electronic cigarettes (e-cigarettes) is a major topic of discussion. The key goals of this study were to examine the contents of e-cigarette vapor and determine if nicotine altered inflammatory responses against respiratory syncytial virus (RSV) infection. E-cigarette vapor was passed through a hollow 3D-model of an adult lung, and gas chromatography detected over 50 compounds passed through the 3D model, including nicotine, propylene glycol (PG), ethanol, methanol, and diacetyl. The murine alveolar macrophage cell line MH-S cells were exposed to nicotine and e-cigarette vapor with and without nicotine. Nicotine significantly induced the expression of matrix metalloprotease (Mmp) 12 and reduced expression of Ifnβ and Tnfα. To examine the role of nicotine in lung defense against RSV infection, A/J mice were exposed to PBS, e-cigarette vapor with and without nicotine for 2 months before RSV infection. E-cigarette vapor did not influence RSV infection-induced animal weight loss, RSV infectivity, airway hyperresponsiveness during methacholine challenge, or immune cell infiltration into the lungs. However, e-cigarette vapor containing nicotine enhanced obstruction and induced secretion of MMP12 and reduced levels of Ifnβ and TNFα. In conclusion, nicotine in vaping products modulates immune responses that may impact the lungs during a respiratory infection.

Acute e-cig inhalation impacts vascular health: a study in smoking naïve subjects

This study was designed to investigate the acute effects of nonnicotinized e-cigarette (e-cig) aerosol inhalation in nonsmokers both in terms of blood-based markers of inflammation and oxidative stress and evaluate their association with hemodynamic-metabolic MRI parameters quantifying peripheral vascular reactivity, cerebrovascular reactivity, and aortic stiffness. Thirty-one healthy nonsmokers were subjected to two blood draws and two identical MRI protocols, each one before and after a standardized e-cig vaping session. After vaping, the serum levels of C-reactive protein, soluble intercellular adhesion molecule, and the danger signal machinery high-mobility group box 1 (HMGB1) and its downstream effector and the NLR family pyrin domain containing 3 (NLRP3) inflammasome (as monitored by its adaptor protein ASC) increased significantly relative to the respective baseline (prevaping) values. Moreover, nitric oxide metabolites and reactive oxygen species production decreased and increased, respectively. These observations were paralleled by impaired peripheral vascular reactivity (with reduced flow-mediated dilation and attenuated hyperemic response after a cuff-occlusion test) and metabolic alterations expressed by decreased venous oxygen saturation, postvaping. The current results suggest propagation of inflammation signaling via activation of the danger signaling axis (HMGB1-NLRP3). The findings indicate that a single episode of vaping has adverse impacts on vascular inflammation and function.NEW & NOTWORTHY Endothelial cell signaling and blood biomarkers were found to correlate with functional vascular changes in a single episode e-cigarettes inhalation in healthy adults. This is indicative of the potential of e-cigarettes (even when inhaled acutely) to lead of vascular dysfunction.

A phospholipid-based formulation for the treatment of airway inflammation in chronic respiratory diseases

Inflammation, the major hallmark of all chronic respiratory diseases is generally managed by inhaled corticosteroids. However, long term high dose treatment can result in significant side effects. Hence, there is a medical need for non-steroidal anti-inflammatory therapies to address airway inflammation. Phospholipids have been shown to reduce inflammation in several inflammatory conditions; however, their clinical translation has been limited to liposomal formulations traditionally used as drug carriers and their biological activity has not been investigated. Here we report the first application of empty liposomes as an anti-inflammatory treatment in airway inflammation. In the current study, liposomes (UTS-001) were prepared from cholesterol and a synthetic phospholipid (DOPC). The formulation was characterised in terms of size, charge, polydispersity index, morphology and stability as colloidal suspension and freeze-dried nanoparticles. Time-dependant uptake of UTS-001 in airway epithelial cells was observed which was inhibited by nystatin demonstrating that the uptake is via the caveolae pathway. In-vitro, in primary nasal epithelial cells, UTS-001 treatment successfully attenuated IL-6 levels following TNF-α stimulation. Consistent with the in-vitro findings, in-vivo, in the ovalbumin model of allergic airway inflammation, UTS-001 significantly reduced total immune cell counts in bronchoalveolar lavage fluid and reduced airway hyperresponsiveness in response to increasing doses of methacholine challenge. Therefore, our results establish UTS-001 as a potential anti-inflammatory treatment that may be useful as a therapeutic for lung inflammatory diseases.

The fog, the attractive and the addictive: pulmonary effects of vaping with a focus on the contribution of each major vaping liquid constituent

Vaping has become increasingly popular over the past decade. This pragmatic review presents the published biological effects of electronic cigarette vapour inhalation with a focus on the pulmonary effects. Special attention has been devoted to providing the documented effects specific to each major ingredient, namely propylene glycol/glycerol, nicotine and flavouring agents. For each ingredient, findings are divided according to the methodology used, being in vitro studies, animal studies and clinical studies. Finally, we provide thoughts and insights on the current state of understanding of the pulmonary effects of vaping, as well as novel research avenues and methodologies.

Electronic-Cigarette Vehicles and Flavoring Affect Lung Function and Immune Responses in a Murine Model

The use of electronic nicotine delivery systems (ENDS), also known as electronic-cigarettes (e-cigs), has raised serious public health concerns, especially in light of the 2019 outbreak of e-cig or vaping product use-associated acute lung injury (EVALI). While these cases have mostly been linked to ENDS that contain vitamin E acetate, there is limited research that has focused on the chronic pulmonary effects of the delivery vehicles (i.e., without nicotine and flavoring). Thus, we investigated lung function and immune responses in a mouse model following exposure to the nearly ubiquitous e-cig delivery vehicles, vegetable glycerin (VG) and propylene glycol (PG), used with a specific 70%/30% ratio, with or without vanilla flavoring. We hypothesized that mice exposed sub-acutely to these e-cig aerosols would exhibit lung inflammation and altered lung function. Adult female C57BL/6 mice (n = 11-12 per group) were exposed to filtered air, 70%/30% VG/PG, or 70%/30% VG/PG with a French vanilla flavoring for 2 h a day for 6 weeks. Prior to sacrifice, lung function was assessed. At sacrifice, broncho-alveolar lavage fluid and lung tissue were collected for lipid mediator analysis, flow cytometry, histopathology, and gene expression analyses. Exposures to VG/PG + vanilla e-cig aerosol increased lung tidal and minute volumes and tissue damping. Immunophenotyping of lung immune cells revealed an increased number of dendritic cells, CD4+ T cells, and CD19+ B cells in the VG/PG-exposed group compared to air, irrespective of the presence of vanilla flavoring. Quantification of bioactive lung lipids demonstrated a >3-fold increase of 2-arachidonoylglycerol (2-AG), an anti-inflammatory mediator, and a 2-fold increase of 12-hydroxyeicosatetraenoic acid (12-HETE), another inflammatory mediator, following VG/PG exposure, with or without vanilla flavoring. This suggests that e-cig aerosol vehicles may affect immunoregulatory molecules. We also found that the two e-cig aerosols dysregulated the expression of lung genes. Ingenuity Pathway Analysis revealed that the gene networks that are dysregulated by the VG/PG e-cig aerosol are associated with metabolism of cellular proteins and lipids. Overall, our findings demonstrate that VG and PG, the main constituents of e-liquid formulations, when aerosolized through an e-cig device, are not harmless to the lungs, since they disrupt immune homeostasis.

Current E-Cigarette Research in the Context of Asthma

PURPOSE OF REVIEW

The purpose of this review is to integrate recent research on the respiratory immune effects of e-cigarettes with the pathogenesis of asthma to better understand how e-cigarettes may affect asthmatics and to note critical knowledge gaps regarding the effects of e-cigarettes on asthmatics.

RECENT FINDINGS

Human, rodent, and cell culture studies show that key cellular functions of epithelial cells, macrophages, and neutrophils are altered by e-cigarette exposure. Because respiratory immunity is already dysregulated in asthma, further alteration of cellular function by e-cigarettes could impact asthma development, severity, and/or exacerbations. Future research is needed to more directly investigate this relationship using controlled human exposure studies and exposure of cell culture or animal models of asthma to e-cigarettes.

The rise of electronic nicotine delivery systems and the emergence of electronic-cigarette-driven disease

In 2019, the United States experienced the emergence of the vaping-associated lung injury (VALI) epidemic. Vaping is now known to result in the development and progression of severe lung disease in the young and healthy. Lack of regulation on electronic cigarettes in the United States has resulted in over 2,000 patients and 68 deaths. We examine the clinical representation of VALI and the delve into the scientific evidence of how deadly exposure to electronic cigarettes can be. E-cigarette vapor is shown to affect numerous cellular processes, cellular metabolism, and cause DNA damage (which has implications for cancer). E-cigarette use is associated with a higher risk of developing crippling lung conditions such as chronic obstructive pulmonary disease (COPD), which would develop several years from now, increasing the already existent smoking-related burden. The role of vaping and virus susceptibility is yet to be determined; however, vaping can increase the virulence and inflammatory potential of several lung pathogens and is also linked to an increased risk of pneumonia. As it has emerged for cigarette smoking, great caution should also be given to vaping in relation to SARS-CoV-2 infection and the COVID-19 pandemic. Sadly, e-cigarettes are continually promoted and perceived as a safer alternative to cigarette smoking. E-cigarettes and their modifiable nature are harmful, as the lungs are not designed for the chronic inhalation of e-cigarette vapor. It is of interest that e-cigarettes have been shown to be of no help with smoking cessation. A true danger lies in vaping, which, if ignored, will lead to disastrous future costs.

Should we worry about children's exposure to third-hand by-products generated from electronic nicotine delivery systems?

Children and other individuals sharing spaces with END users frequently become exposed to first-, second- and third-hand chemicals. This editorial discusses the findings from a recent study exploring the impact of third-hand exposure. https://bit.ly/3cogiw0.

Potential effects of E-cigarettes and vaping on pediatric asthma

Asthma is the most common chronic disease in childhood and exposure to tobacco smoke has been long recognized as a risk factor for its onset as well as for exacerbations and poor disease control. Since the early 2000s, electronic cigarettes have been marketed worldwide as a non-harmful electronic alternative to combustible cigarettes and as a device likely to help stop smoking, and their use is continuously rising, particularly among adolescents. However, several studies have shown that vape contains many different well-known toxicants, causing significant cytotoxic and pro-inflammatory effects on the airways in-vitro and in animal models. In humans, a variety of harmful lung effects related to vaping, ranging from bronchoconstriction to severe respiratory distress has been already reported. To investigate the potential effects of vaping in pediatric asthma, we searched relevant published studies in the MEDLINE/PubMed database by combining the adequate Medical Subject Headings terms and key words. At the end of our study selection process, five cross-sectional studies focusing on electronic cigarettes use in adolescents and self-reported asthma and/or other respiratory symptoms, one study focusing on the effects of electronic cigarettes second-hand exposure and one case report were retrieved. These preliminary data support a likely detrimental effect of vaping in asthmatic adolescents. Currently available evidence supports that electronic cigarettes are a potential threat to respiratory health, particularly in adolescents with asthma. High-quality studies on larger population assessing the long-term effects of vape exposure, are urgently needed.

Clinical Features of E-cigarette, or Vaping, Product Use-Associated Lung Injury in Teenagers

BACKGROUND

In the United States in 2019, there was an outbreak of electronic cigarette, or vaping, product use-associated lung injury (EVALI). The manifestations of EVALI in adolescents are not well characterized. We describe the diagnosis, evaluation, and management of EVALI in adolescents hospitalized at a tertiary care, university-affiliated children's hospital.

METHODS

A multidisciplinary committee developed an EVALI algorithm on the basis of guidelines from the Centers for Disease Control and Prevention. A retrospective chart review was conducted on patients diagnosed with EVALI. Descriptive analyses included sociodemographic characteristics, clinical presentation, laboratory and imaging results, pulmonary function testing, oxygen requirements, and clinic follow-up.

RESULTS

Thirteen hospitalized adolescents were diagnosed with confirmed or probable EVALI. The majority were female (54%) with a mean age of 15.9 years. Sixty-nine percent of patients presented with respiratory symptoms, whereas gastrointestinal symptoms were prominent in 85% of patients. Vaping Δ-9-tetrahydrocannabinol was reported in 92% of patients, and vaping nicotine was reported in 62% of patients. All had bilateral ground-glass opacities on the chest computed tomography (CT) scan. Treatment with glucocorticoids led to clinical improvement in 11 of 12 patients. Treatment with glucocorticoids led to improvement in both forced expiratory volume in 1 second and forced vital capacity (P < .05). Four patients required home oxygen on the basis of 6-minute walk test results.

CONCLUSIONS

Diagnosis of EVALI should be suspected on the basis of vaping history and clinical presentation. Glucocorticoid treatment led to an improvement in symptoms and lung function. The 6-minute walk test may help determine oxygen needs at discharge.

E-cigarettes damage the liver and alter nutrient metabolism in pregnant mice and their offspring

Approximately 15% of pregnant women vape electronic cigarettes (e-cigarettes), exposing the fetus to a range of toxic compounds, including nicotine and by-products of e-cigarette liquid (e-liquid) pyrolysis. Owing to the recent emergence of these products, research mainly focuses on immediate users, and not on in utero exposure. Therefore, this study aimed to understand the impact of intrauterine e-cigarette vapor (e-vapor) exposure, with and without nicotine, on liver metabolic markers in the male offspring. E-vapor was generated using an e-cigarette filled with tobacco-flavored e-liquid (18 or 0 mg/mL nicotine). Female Balb/c mice were exposed to e-vapor for 6 weeks before mating, through gestation and lactation, without direct exposure to the offspring. Livers and plasma from dams and male offspring (13 weeks old) were examined. Exposure to nicotine-free e-vapor promoted metabolic changes and liver damage in both the dams and their offspring. Furthermore, exposure to nicotine-containing e-vapor did not cause liver damage but induced hepatic steatosis in the adult offspring. Therefore, maternal vaping is detrimental to both the dams and their offspring, with nicotine providing a potential protective effect.

Inhalation Toxicology of Vaping Products and Implications for Pulmonary Health

E-cigarettes have a liquid that may contain flavors, solvents, and nicotine. Heating this liquid generates an aerosol that is inhaled into the lungs in a process commonly referred to as vaping. E-cigarette devices can also contain cannabis-based products including tetrahydrocannabinol (THC), the psychoactive component of cannabis (marijuana). E-cigarette use has rapidly increased among current and former smokers as well as youth who have never smoked. The long-term health effects are unknown, and emerging preclinical and clinical studies suggest that e-cigarettes may not be harmless and can cause cellular alterations analogous to traditional tobacco smoke. Here, we review the historical context and the components of e-cigarettes and discuss toxicological similarities and differences between cigarette smoke and e-cigarette aerosol, with specific reference to adverse respiratory outcomes. Finally, we outline possible clinical disorders associated with vaping on pulmonary health and the recent escalation of acute lung injuries, which led to the declaration of the vaping product use-associated lung injury (EVALI) outbreak. It is clear there is much about vaping that is not understood. Consequently, until more is known about the health effects of vaping, individual factors that need to be taken into consideration include age, current and prior use of combustible tobacco products, and whether the user has preexisting lung conditions such as asthma and chronic obstructive pulmonary disease (COPD).

A Summary of In Vitro and In Vivo Studies Evaluating the Impact of E-Cigarette Exposure on Living Organisms and the Environment

Worldwide use of electronic cigarettes has been rapidly expanding over recent years, but the long-term effect of e-cigarette vapor exposure on human health and environment is not well established; however, its mechanism of action entails the production of reactive oxygen species and trace metals, and the exacerbation of inflammation, which are associated with potential cytotoxicity and genotoxicity. The present study examines the effects of selected liquid chemicals used in e-cigarettes, such as propylene glycol/vegetable glycerin, nicotine and flavorings, on living organisms; the data collected indicates that exposure to e-cigarette liquid has potentially detrimental effects on cells in vitro, and on animals and humans in vivo. While e-liquid exposure can adversely influence the physiology of living organisms, vaping is recommended as an alternative for tobacco smoking. The study also compares the impact of e-cigarette liquid exposure and traditional cigarette smoke on organisms and the environmental impact. The environmental influence of e-cigarette use is closely connected with the emission of airborne particulate matter, suggesting the possibility of passive smoking. The obtained data provides an insight into the impact of nicotine delivery systems on living organisms and the environment.

Systemic biomarkers in electronic cigarette users: implications for noninvasive assessment of vaping-associated pulmonary injuries

Background

Electronic cigarettes (e-cigs) were introduced as electronic nicotine delivery systems, and have become very popular in the USA and globally. There is a paucity of data on systemic injury biomarkers of vaping in e-cig users that can be used as a noninvasive assessment of vaping-associated lung injuries. We hypothesised that characterisation of systemic biomarkers of inflammation, anti-inflammatory, oxidative stress, vascular and lipid mediators, growth factors, and extracellular matrix breakdown may provide information regarding the toxicity of vaping in e-cig users.

Methods

We collected various biological fluids, i.e. plasma, urine, saliva and exhaled breath condensate (EBC), measured pulmonary function and vaping characteristics, and assessed various biomarkers in e-cig users and nonusers.

Results

The plasma samples of e-cig users showed a significant increase in biomarkers of inflammation (interleukin (IL)-1β, IL-6, IL-8, IL-13, interferon (IFN)-γ, matrix metalloproteinase-9, intercellular cell adhesion molecule-1) and extracellular matrix breakdown (desmosine), and decreased pro-resolving lipid mediators (resolvin D₁ and resolvin D₂). There was a significant increase in growth factor (endothelial growth factor, vascular endothelial growth factor, β-nerve growth factor, platelet-derived growth factor-AA, stem cell factor, hepatocyte growth factor and placental growth factor) levels in plasma of e-cig users versus nonusers. E-cig users showed a significant increase in levels of inflammatory biomarker IFN-γ, oxidative stress biomarker 8-isoprostane and oxidative DNA damage biomarker 8-oxo-dG in urine samples, and of inflammatory biomarker IL-1β in saliva samples. EBC showed a slight increase in levels of triglycerides and 8-isoprostane in e-cig users compared with normal nonusers.

Conclusion

E-cig users have increased levels of biomarkers of inflammation and oxidative stress, reduced pro-resolving anti-inflammatory mediators, and endothelial dysfunction, which may act as risk factors for increasing susceptibility to systemic diseases. The identified noninvasive biomarkers can be used for determining e-cig vaping-associated lung injuries, and for regulatory and diagnostic aspects of vaping in humans.

E-cig use adversely affects oxidative stress and inflammatory responses, and induces tissue remodelling. The identified biomarkers can be used for assessment of vaping-associated lung injuries, and for regulatory and diagnostic aspects of vaping in humans.http://bit.ly/2nxZQ8R