Chronic E-Cigarette Exposure Alters the Human Bronchial Epithelial Proteome

Electronic Cigarettes: Past, Present, and Future: What Clinicians Need to Know

Electronic cigarettes (EC) are battery-operated devices that heat and aerosolize a liquid solution that typically contains nicotine. ECs have become commonly used among youth and may pose substantial risks of future addiction and health problems in this population. However, ECs are far less toxic per puff compared with combustible cigarettes, and as a result, might present an important harm reduction opportunity for cigarette smokers who cannot stop smoking by traditional means. The long-term health effects of ECs on individuals and the net effect on public health will remain unknown for many years.

E-cigarette constituents propylene glycol and vegetable glycerin decrease glucose uptake and its metabolism in airway epithelial cells in vitro

Electronic nicotine delivery systems, or e-cigarettes, utilize a liquid solution that normally contains propylene glycol (PG) and vegetable glycerin (VG) to generate vapor and act as a carrier for nicotine and flavorings. Evidence indicated these "carriers" reduced growth and survival of epithelial cells including those of the airway. We hypothesized that 3% PG or PG mixed with VG (3% PG/VG, 55:45) inhibited glucose uptake in human airway epithelial cells as a first step to reducing airway cell survival. Exposure of H441 or human bronchiolar epithelial cells (HBECs) to PG and PG/VG (30-60 min) inhibited glucose uptake and mitochondrial ATP synthesis. PG/VG inhibited glycolysis. PG/VG and mannitol reduced cell volume and height of air-liquid interface cultures. Mannitol, but not PG/VG, increased phosphorylation of p38 MAPK. PG/VG reduced transepithelial electrical resistance, which was associated with increased transepithelial solute permeability. PG/VG decreased fluorescence recovery after photobleaching of green fluorescent protein-linked glucose transporters GLUT1 and GLUT10, indicating that glucose transport function was compromised. Puffing PG/VG vapor onto the apical surface of primary HBECs for 10 min to mimic the effect of e-cigarette smoking also reduced glucose transport. In conclusion, short-term exposure to PG/VG, key components of e-cigarettes, decreased glucose transport and metabolism in airway cells. We propose that this was a result of PG/VG reduced cell volume and membrane fluidity, with further consequences on epithelial barrier function. Taking these results together, we suggest these factors contribute to reduced defensive properties of the epithelium. We propose that repeated/chronic exposure to these agents are likely to contribute to airway damage in e-cigarette users.

E-Cigarette or Vaping Product Use-Associated Lung Injury: A Severe Case That Responded to Corticosteroid Treatment

Vaping is associated with an increased risk of lung injury; however, each case of vaping-associated lung injury leads to varying degrees of lung injury, and the response to therapy can be heterogeneous. Corticosteroid use has been suggested as a treatment for lung injuries associated with vaping.

We report a case of e-cigarette or vaping product use-associated lung injury (EVALI) that resulted in acute hypoxic respiratory failure. A 20-year-old woman presented with complaints of sore throat, dry cough, shortness of breath, and pleuritic chest pain. The patient admitted to vaping regularly for the past three years. The patient was found to be severely hypoxemic with respiratory distress and was intubated shortly after her arrival at the emergency department. She was treated with a short course of corticosteroids with tapering of the dose based on her response with significant improvement, and she was extubated on the seventh day of her admission.

EVALI is a syndrome associated with severe lung injury that results in acute respiratory failure that is clinically indistinguishable from acute respiratory distress syndrome, and it is largely a diagnosis of exclusion. The use of systemic corticosteroids in treating these patients should be considered after excluding an infectious etiology.

Menthol in electronic cigarettes: A contributor to respiratory disease?

Menthol is widely used in tobacco products. This study compared the effects of menthol on human bronchial epithelium using submerged cultures, a VITROCELL® cloud chamber that provides air liquid interface (ALI) exposure without solvents or heating, and a Cultex ALI system that delivers aerosol equivalent to that inhaled during vaping. In submerged culture, menthol significantly increased calcium influx and mitochondrial reactive oxygen species (ROS) via the TRPM8 receptor, responses that were inhibited by a TRPM8 antagonist. VITROCELL® cloud chamber exposure of BEAS-2B monolayers increased mitochondrial protein oxidation, expression of the antioxidant enzyme SOD2, activation of NF-κB, and secretion of inflammatory cytokines (IL-6 and IL-8). Proteomics data collected following ALI exposure of 3D EpiAirway tissue in the Cultex showed upregulation of NRF-2-mediated oxidative stress, oxidative phosphorylation, and IL-8 signaling. Across the three platforms, menthol adversely effected human bronchial epithelium in a manner that could lead to respiratory disease.

Effect of e-Cigarettes Plus Counseling vs Counseling Alone on Smoking Cessation: A Randomized Clinical Trial

IMPORTANCE

Electronic cigarettes (e-cigarettes) for smoking cessation remain controversial.

OBJECTIVE

To evaluate e-cigarettes with individual counseling for smoking cessation.

DESIGN, SETTING, AND PARTICIPANTS

A randomized clinical trial enrolled adults motivated to quit smoking from November 2016 to September 2019 at 17 Canadian sites (801 individuals screened; 274 ineligible and 151 declined). Manufacturing delays resulted in early termination (376/486 participants, 77% of target). Outcomes through 24 weeks (March 2020) are reported.

INTERVENTIONS

Randomization to nicotine e-cigarettes (n = 128), nonnicotine e-cigarettes (n = 127), or no e-cigarettes (n = 121) for 12 weeks. All groups received individual counseling.

MAIN OUTCOMES AND MEASURES

The primary end point was point prevalence abstinence (7-day recall, biochemically validated using expired carbon monoxide) at 12 weeks, changed from 52 weeks following early termination. Participants missing data were assumed to be smoking. The 7 secondary end points, examined at multiple follow-ups, were point prevalence abstinence at other follow-ups, continuous abstinence, daily cigarette consumption change, serious adverse events, adverse events, dropouts due to adverse effects, and treatment adherence.

RESULTS

Among 376 randomized participants (mean age, 52 years; 178 women [47%]), 299 (80%) and 278 (74%) self-reported smoking status at 12 and 24 weeks, respectively. Point prevalence abstinence was significantly greater for nicotine e-cigarettes plus counseling vs counseling alone at 12 weeks (21.9% vs 9.1%; risk difference [RD], 12.8 [95% CI, 4.0 to 21.6]) but not 24 weeks (17.2% vs 9.9%; RD, 7.3 [95% CI, -1.2 to 15.7]). Point prevalence abstinence for nonnicotine e-cigarettes plus counseling was not significantly different from counseling alone at 12 weeks (17.3% vs 9.1%; RD, 8.2 [95% CI, -0.1 to 16.6]), but was significantly greater at 24 weeks (20.5% vs 9.9%; RD, 10.6 [95% CI, 1.8 to 19.4]). Adverse events were common (nicotine e-cigarette with counseling: 120 [94%]; nonnicotine e-cigarette with counseling: 118 [93%]; counseling only: 88 [73%]), with the most common being cough (64%) and dry mouth (53%).

CONCLUSIONS AND RELEVANCE

Among adults motivated to quit smoking, nicotine e-cigarettes plus counseling vs counseling alone significantly increased point prevalence abstinence at 12 weeks. However, the difference was no longer significant at 24 weeks, and trial interpretation is limited by early termination and inconsistent findings for nicotine and nonnicotine e-cigarettes, suggesting further research is needed.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02417467.

E-cigarette use and respiratory disorders: an integrative review of converging evidence from epidemiological and laboratory studies

BACKGROUND

Use of electronic cigarettes (e-cigarettes) is prevalent among adolescents and young adults, but there has been limited knowledge about health consequences in human populations. We conduct a systematic review and meta-analysis of results on respiratory disorders from studies of general-population samples and consider the mapping of these results to findings about biological processes linked to e-cigarettes in controlled laboratory studies.

METHOD

We conducted a literature search and meta-analysis of epidemiological studies on the association of e-cigarette use with asthma and with COPD. We discuss findings from laboratory studies about effects of e-cigarettes on four biological processes: cytotoxicity, oxidative stress/inflammation, susceptibility to infection and genetic expression.

RESULTS

Epidemiological studies, both cross-sectional and longitudinal, show a significant association of e-cigarette use with asthma and COPD, controlling for cigarette smoking and other covariates. For asthma (n=15 studies), the pooled adjusted odds ratio (aOR) was 1.39 (95% CI 1.28-1.51); for COPD (n=9 studies) the aOR was 1.49 (95% CI 1.36-1.65). Laboratory studies consistently show an effect of e-cigarettes on biological processes related to respiratory harm and susceptibility to illness, with e-cigarette conditions differing significantly from clean-air controls, although sometimes less than for cigarettes.

CONCLUSIONS

The evidence from epidemiological studies meets established criteria for consistency, strength of effect, temporality, and in some cases a dose-response gradient. Biological plausibility is indicated by evidence from multiple laboratory studies. We conclude that e-cigarette use has consequences for asthma and COPD, which is of concern for respirology and public health.

E-Cigarette Promotion on Twitter in Australia: Content Analysis of Tweets

BACKGROUND

The sale of electronic cigarettes (e-cigarettes) containing nicotine is prohibited in all Australian states and territories; yet, the growing availability and convenience of the internet enable the promotion and exposure of e-cigarettes across countries. Social media's increasing pervasiveness has provided a powerful avenue to market products and influence social norms and risk behaviors. At present, there is no evidence of how e-cigarettes and vaping are promoted on social media in Australia.

OBJECTIVE

This study aimed to investigate how e-cigarettes are portrayed and promoted on Twitter through a content analysis of vaping-related tweets containing an image posted and retweeted by Australian users and how the portrayal and promotion have emerged and trended over time.

METHODS

In total, we analyzed 1303 tweets and accompanying images from 2012, 2014, 2016, and 2018 collected through the Tracking Infrastructure for Social Media Analysis (TrISMA), a contemporary technical and organizational infrastructure for the tracking of public communication by Australian users of social media, via a list of 15 popular e-cigarette-related terms.

RESULTS

Despite Australia's cautious approach toward e-cigarettes and the limited evidence supporting them as an efficacious smoking cessation aid, it is evident that there is a concerted effort by some Twitter users to promote these devices as a health-conducive (91/129, 70.5%), smoking cessation product (266/1303, 20.41%). Further, Twitter is being used in an attempt to circumvent Australian regulation and advocate for a more liberal approach to personal vaporizers (90/1303, 6.90%). A sizeable proportion of posts was dedicated to selling or promoting vape products (347/1303, 26.63%), and 19.95% (260/1303) were found to be business listings. These posts used methods to try and expand their clientele further than immediate followers by touting competitions and giveaways, with those wanting to enter having to perform a sequence of steps such as liking, tagging, and reposting, ultimately exposing the post among the user's network and to others not necessarily interested in vaping.

CONCLUSIONS

The borderless nature of social media presents a clear challenge for enforcing Article 13 of the World Health Organization Framework Convention on Tobacco Control, which requires all ratifying nations to implement a ban on tobacco advertising, promotion, and sponsorship. Countering the advertising and promotion of these products is a public health challenge that will require cross-border cooperation with other World Health Organization Framework Convention on Tobacco Control parties. Further research aimed at developing strategies to counter the advertising and promotion of e-cigarettes is therefore needed.

An update on controversies in e-cigarettes

E-cigarettes are electronic nicotine delivery systems (ENDS) which mimic tobacco smoking without the combustion of tobacco. These devices have been misleadingly marketed as "less harmful" alternatives to conventional smoking tobacco products. The e-liquid in e-cigarettes include nicotine, a humectant and other additives including flavourings, colourants, or adulterants such as bacterial and fungal products. In this review, we discuss the contrasting views of the tobacco lobby and most professional societies. We describe the epidemiology of the use of these devices, with a widespread and significant rise in youth e-cigarette use seen in both the USA and Europe. We also describe what is known about the toxicity and mechanisms of EVALI (e-cigarette or vaping associated lung injury). This characterised by respiratory failure with an intense inflammatory response. The presentations are diverse and clinicians should consider vaping as a possible cause of any unusual respiratory illness in patients who have a history of vaping or other use of e-cigarette-related products. Second hand exposure to e-cigarettes is also harmful through respiration and transdermal absorption. E-cigarettes have a worse acute toxicity than tobacco and their long-term toxicity is unknown, and we advocate for the immediate, most vigorous anti-vaping legislation possible.

Assessing Human Airway Epithelial Progenitor Cells for Cystic Fibrosis Cell Therapy

Cystic fibrosis (CF) is caused by loss-of-function mutations in the CFTR (CF transmembrane regulator) gene. Pharmacologic therapies directed at CFTR have been developed but are not effective for mutations that result in little or no mRNA or protein expression. Cell therapy is a potential mutation-agnostic approach to treatment. One strategy is to harvest human bronchial epithelial cells (HBECs) for gene addition or genetic correction, followed by expansion and engraftment. This approach will require cells to grow extensively while retaining their ability to reconstitute CFTR activity. We hypothesized that conditionally reprogrammed cell (CRC) technology, namely growth in the presence of irradiated feeder cells and a Rho kinase inhibitor, would enable expansion while maintaining cell capacity to express functional CFTR. Our goal was to compare expression of the basal cell marker NGFR (nerve growth factor receptor) and three-dimensional bronchosphere colony-forming efficiency (CFE) in early- and later-passage HBECs grown using nonproprietary bronchial epithelial growth medium or the CRC method. Cell number and CFTR activity were determined in a competitive repopulation assay employing chimeric air-liquid interface cultures. HBECs expanded using the CRC method expressed the highest NGFR levels, had the greatest 3D colony-forming efficiency at later passage, generated greater cell numbers in chimeric cultures, and most effectively reconstituted CFTR activity. In our study, the HBEC air-liquid interface model, an informative testing platform proven vital for the development of other CF therapies, illustrated that cells grown by CRC technology or equivalent methods may be useful for cell therapy of CF.

Acute Respiratory Failure Associated With Vaping

The use of e-cigarettes to deliver aerosolized nicotine has gained popularity in recent years. Numerous reports have cited the development of acute pulmonary disease linked to vaping nicotine as well as marijuana-based products. As cultural attitudes evolve and policies shift toward the legalization of marijuana, its use has become more prevalent. Given the increased prevalence of marijuana consumption and e-cigarette usage, better insight into its potential to cause lung toxicity is warranted. The clinical, radiographic, and histopathologic characteristics of lung injury associated with vaping, particularly with marijuana-based products, have yet to be well described in the literature. We present eight patients, most of whom were admitted recently to our institution with acute respiratory failure following vaping. The majority of patients were young, with a median age of 31.5 years (range, 24-62 years) and with no known underlying lung disease. This case series highlights common clinical findings as well as the varied radiographic and histopathologic features of acute respiratory failure associated with vaping predominantly marijuana-based products. As more cases of vaping-associated pulmonary injury unfold, data will be available to further characterize this emerging disease entity. Improved understanding of disease pathogenesis and its clinical course will help clinicians determine optimal management and follow-up strategies for this patient population.

Cellular effects of nicotine salt-containing e-liquids

"Pod-based" e-cigarettes such as JUUL are currently the most prevalent electronic nicotine delivery systems (ENDS) in the United States. JUUL-type ENDS utilize nicotine salts protonated with benzoic acid rather than freebase nicotine. However, limited information is available on the cellular effects of these products. Cytoplasmic Ca²⁺ is a universal second messenger that controls many cellular functions including cell growth and cell death. Of note, dysregulation of cell Ca²⁺ homeostasis has been linked with several disease processes including autoimmune disease and several types of cancer. We exposed HEK293T cells and THP-1 macrophage-like cells to different JUUL e-liquids. We evaluated their effects on cellular viability and Ca²⁺ signaling by measuring fluorescence from calcein-AM/propidium iodide and Fluo-4, respectively. E-liquid autofluorescence was used to look for e-liquid permeation into cells. To identify the mechanisms behind the Ca²⁺ responses, different inhibitors of Ca²⁺ channels and phospholipase C signaling were used. JUUL e-liquids caused significant cytotoxic effects, with "Mint" flavor being the most cytotoxic. The Mint flavored e-liquid also caused a significant elevation in cytoplasmic Ca²⁺ . Using autofluorescence, the permeation of JUUL e-liquids into live cells was confirmed, indicating that intracellular organelles are directly exposed to e-liquids. Further studies identified the endoplasmic reticulum as being the source of e-liquid-induced changes in cytoplasmic Ca²⁺ . Nicotine salt-based e-liquids cause cytotoxicity and elevate cytoplasmic Ca²⁺ , indicating that they can exert biological effects beyond what would be expected with nicotine alone. These effects are flavor-dependent, and we propose that flavored e-liquids be reassessed for potential lung toxicity.

Electronic cigarettes: A position statement from the Thoracic Society of Australia and New Zealand

The TSANZ develops position statements where insufficient data exist to write formal clinical guidelines. In 2018, the TSANZ addressed the question of potential benefits and health impacts of electronic cigarettes (EC). The working party included groups focused on health impacts, smoking cessation, youth issues and priority populations. The 2018 report on the Public Health Consequences of E-Cigarettes from the United States NASEM was accepted as reflective of evidence to mid-2017. A search for papers subsequently published in peer-reviewed journals was conducted in August 2018. A small number of robust and important papers published until March 2019 were also identified and included. Groups identified studies that extended, modified or contradicted the NASEM report. A total of 3793 papers were identified and reviewed, with summaries and draft position statements developed and presented to TSANZ membership in April 2019. After feedback from members and external reviewers, a collection of position statements was finalized in December 2019. EC have adverse lung effects and harmful effects of long-term use are unknown. EC are unsuitable consumer products for recreational use, part-substitution for smoking or long-term exclusive use by former smokers. Smokers who require support to quit smoking should be directed towards approved medication in conjunction with behavioural support as having the strongest evidence for efficacy and safety. No specific EC product can be recommended as effective and safe for smoking cessation. Smoking cessation claims in relation to EC should be assessed by established regulators.

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.

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.

SARS-CoV-2 Reverse Genetics Reveals a Variable Infection Gradient in the Respiratory Tract

The mode of acquisition and causes for the variable clinical spectrum of coronavirus disease 2019 (COVID-19) remain unknown. We utilized a reverse genetics system to generate a GFP reporter virus to explore severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogenesis and a luciferase reporter virus to demonstrate sera collected from SARS and COVID-19 patients exhibited limited cross-CoV neutralization. High-sensitivity RNA in situ mapping revealed the highest angiotensin-converting enzyme 2 (ACE2) expression in the nose with decreasing expression throughout the lower respiratory tract, paralleled by a striking gradient of SARS-CoV-2 infection in proximal (high) versus distal (low) pulmonary epithelial cultures. COVID-19 autopsied lung studies identified focal disease and, congruent with culture data, SARS-CoV-2-infected ciliated and type 2 pneumocyte cells in airway and alveolar regions, respectively. These findings highlight the nasal susceptibility to SARS-CoV-2 with likely subsequent aspiration-mediated virus seeding to the lung in SARS-CoV-2 pathogenesis. These reagents provide a foundation for investigations into virus-host interactions in protective immunity, host susceptibility, and virus pathogenesis.

SARS-CoV-2 Reverse Genetics Reveals a Variable Infection Gradient in the Respiratory Tract

The mode of acquisition and causes for the variable clinical spectrum of coronavirus disease 2019 (COVID-19) remain unknown. We utilized a reverse genetics system to generate a GFP reporter virus to explore severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogenesis and a luciferase reporter virus to demonstrate sera collected from SARS and COVID-19 patients exhibited limited cross-CoV neutralization. High-sensitivity RNA in situ mapping revealed the highest angiotensin-converting enzyme 2 (ACE2) expression in the nose with decreasing expression throughout the lower respiratory tract, paralleled by a striking gradient of SARS-CoV-2 infection in proximal (high) versus distal (low) pulmonary epithelial cultures. COVID-19 autopsied lung studies identified focal disease and, congruent with culture data, SARS-CoV-2-infected ciliated and type 2 pneumocyte cells in airway and alveolar regions, respectively. These findings highlight the nasal susceptibility to SARS-CoV-2 with likely subsequent aspiration-mediated virus seeding to the lung in SARS-CoV-2 pathogenesis. These reagents provide a foundation for investigations into virus-host interactions in protective immunity, host susceptibility, and virus pathogenesis.

Where there's smoke, there's fire: what current and future providers do and do not know about electronic cigarettes

Background

Health care providers play a pivotal role as educators on health-related matters ranging from vaccination to smoking cessation. With the rising popularity of electronic cigarettes (e-cigarettes), providers face a new challenge. To date, studies have identified a general lack of knowledge among providers regarding e-cigarettes and discomfort with counseling patients on e-cigarette use. This study aims to systematically explore the perspectives of different health care providers on e-cigarettes and their health implications. With a growing availability of research on the health consequences of e-cigarette use, our study also aims to assess the familiarity of our participants with this literature.

Methods

From July to October 2018, a sample of attendings (n = 15), residents (n = 15), medical students (n = 33), and nursing students (n = 28) from Thomas Jefferson University participated in a freelisting interview and survey.

Results

Our study found that perceptions of e-cigarettes vary across different participant groups, as evidenced by the range of responses when asked to think about e-cigarettes and their health implications. We identified gaps in knowledge among students regarding FDA regulation of e-cigarettes and found that attending physicians are less aware than junior trainees of the prevalence of use. Familiarity with evidence-based health consequences was variable and low across all groups. Finally, participants most commonly reported learning about e-cigarettes from news outlets and social media rather than professional platforms.

Conclusion

This study highlights the need for curricular development in nursing and medical schools, residency training, and continuing medical education regarding e-cigarette use and their impact on human health.

In Vitro Toxicity and Chemical Characterization of Aerosol Derived from Electronic Cigarette Humectants Using a Newly Developed Exposure System

In the United States, the recent surge of electronic cigarette (e-cig) use has raised questions concerning the safety of these devices. This study seeks to assess the pro-inflammatory and cellular stress effects of the vaped humectants propylene glycol (PG) and glycerol (GLY) on airway epithelial cells (16HBE cells and differentiated human bronchial epithelial cells) with a newly developed aerosol exposure system. This system allows for chemical characterization of e-cig generated aerosol particles as well as in vitro exposures of 16HBE cells at an air-liquid interface to vaped PG and GLY aerosol. Our data demonstrate that the process of vaping results in the formation of PG- and GLY-derived oligomers in the aerosol particles. Our in vitro data demonstrate an increase in pro-inflammatory cytokines IL-6 and IL-8 levels in response to vaped PG and GLY exposures. Vaped GLY also causes an increase in cellular stress signals HMOX1, NQO1, and carbonylated proteins when the e-cig device is operated at high wattages. Additionally, we find that the exposure of vaped PG causes elevated IL-6 expression, while the exposure of vaped GLY increases HMOX1 expression in human bronchial epithelial cells when the device is operated at high wattages. These findings suggest that vaporizing PG and GLY results in the formation of novel compounds and the exposure of vaped PG and GLY are detrimental to airway cells. Since PG and/or GLY is universally contained in all e-cig liquids, we conclude that these components alone can cause harm to the airway epithelium.

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.

E-cigarettes, nicotine, the lung and the brain: multi-level cascading pathophysiology

Tobacco smoking is highly addictive and causes respiratory disease, cardiovascular disease and multiple types of cancer. Electronic-cigarettes (e-cigarettes) are non-combustible tobacco alternatives that aerosolize nicotine and flavouring agents in a propylene glycol-vegetable glycerine vehicle. They were originally envisaged as a tobacco cessation aid, but whether or not they help people to quit tobacco use is controversial. In this review, we have compared and contrasted what is known regarding the effects of nicotine on the lungs vs. the effects of nicotine in the brain in the context of addiction. Critically, both combustible tobacco products and e-cigarettes contain nicotine, a highly addictive, plant-derived alkaloid that binds to nicotinic acetylcholine receptors (nAChRs). Nicotine's reinforcing properties are primarily mediated by activation of the brain's mesolimbic reward circuitry and release of the neurotransmitter dopamine that contribute to the development of addiction. Moreover, nicotine addiction drives repeated intake that results in chronic pulmonary exposure to either tobacco smoke or e-cigarettes despite negative respiratory symptoms. Beyond the brain, nAChRs are also highly expressed in peripheral neurons, epithelia and immune cells, where their activation may cause harmful effects. Thus, nicotine, a key ingredient of both conventional and electronic cigarettes, produces neurological effects that drive addiction and may damage the lungs in the process, producing a complex, multilevel pathological state. We conclude that vaping needs to be studied by multi-disciplinary teams that include pulmonary and neurophysiologists as well as behaviourists and addiction specialists to fully understand their impact on human physiology.

Electronic cigarettes disrupt lung lipid homeostasis and innate immunity independent of nicotine

Electronic nicotine delivery systems (ENDS) or e-cigarettes have emerged as a popular recreational tool among adolescents and adults. Although the use of ENDS is often promoted as a safer alternative to conventional cigarettes, few comprehensive studies have assessed the long-term effects of vaporized nicotine and its associated solvents, propylene glycol (PG) and vegetable glycerin (VG). Here, we show that compared with smoke exposure, mice receiving ENDS vapor for 4 months failed to develop pulmonary inflammation or emphysema. However, ENDS exposure, independent of nicotine, altered lung lipid homeostasis in alveolar macrophages and epithelial cells. Comprehensive lipidomic and structural analyses of the lungs revealed aberrant phospholipids in alveolar macrophages and increased surfactant-associated phospholipids in the airway. In addition to ENDS-induced lipid deposition, chronic ENDS vapor exposure downregulated innate immunity against viral pathogens in resident macrophages. Moreover, independent of nicotine, ENDS-exposed mice infected with influenza demonstrated enhanced lung inflammation and tissue damage. Together, our findings reveal that chronic e-cigarette vapor aberrantly alters the physiology of lung epithelial cells and resident immune cells and promotes poor response to infectious challenge. Notably, alterations in lipid homeostasis and immune impairment are independent of nicotine, thereby warranting more extensive investigations of the vehicle solvents used in e-cigarettes.

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.

Effects of Electronic Cigarettes on Indoor Air Quality and Health

With the rapid increase in electronic cigarette (e-cig) users worldwide, secondhand exposure to e-cig aerosols has become a serious public health concern. We summarize the evidence on the effects of e-cigs on indoor air quality, chemical compositions of mainstream and secondhand e-cig aerosols, and associated respiratory and cardiovascular effects. The use of e-cigs in indoor environments leads to high levels of fine and ultrafine particles similar to tobacco cigarettes (t-cigs). Concentrations of chemical compounds in e-cig aerosols are generally lower than those in t-cig smoke, but a substantial amount of vaporized propylene glycol, vegetable glycerin, nicotine, and toxic substances, such as aldehydes and heavy metals, has been reported. Exposures to mainstream e-cig aerosols have biologic effects but only limited evidence shows adverse respiratory and cardiovascular effects in humans. Long-term studies are needed to better understand the dosimetry and health effects of exposures to secondhand e-cig aerosols.

Effects of Electronic Cigarettes on Indoor Air Quality and Health

With the rapid increase in electronic cigarette (e-cig) users worldwide, secondhand exposure to e-cig aerosols has become a serious public health concern. We summarize the evidence on the effects of e-cigs on indoor air quality, chemical compositions of mainstream and secondhand e-cig aerosols, and associated respiratory and cardiovascular effects. The use of e-cigs in indoor environments leads to high levels of fine and ultrafine particles similar to tobacco cigarettes (t-cigs). Concentrations of chemical compounds in e-cig aerosols are generally lower than those in t-cig smoke, but a substantial amount of vaporized propylene glycol, vegetable glycerin, nicotine, and toxic substances, such as aldehydes and heavy metals, has been reported. Exposures to mainstream e-cig aerosols have biologic effects but only limited evidence shows adverse respiratory and cardiovascular effects in humans. Long-term studies are needed to better understand the dosimetry and health effects of exposures to secondhand e-cig aerosols.

Benefits of e-cigarettes in smoking reduction and in pulmonary health among chronic smokers undergoing a lung cancer screening program at 6 months

INTRODUCTION

Electronic cigarettes (e-cigarettes) might be a valid and safe device to support smoking cessation. However, the available evidence is divergent. The aim of the present work was to assess the effects of an e-cigarette program on pulmonary health (cough, breath shortness, catarrh) and to evaluate the effectiveness of e-cigarettes in reducing tobacco consumption.

METHODS

The study is a double-blind randomized controlled trial. Two hundred and ten smokers were randomized into three groups: nicotine e-cigarette (8 mg/mL nicotine concentration), nicotine-free e-cigarettes (placebo), and control with 1:1:1 ratio. All participants received a 3 months cessation program that included a cognitive-behavioral intervention aimed at supporting people in changing their behavior and improving motivation to quit.

RESULTS

Pulmonary health, assessed with self-reported measures, clinical evaluations and the Leicester Cough Questionnaire, improved in participants who stopped smoking compared to their own baseline. No differences in pulmonary health were found between groups. Statistical tests showed a significant effect of Group (F (2, 118) = 4.005, p < .020) on daily cigarette consumption: after 6 months participants in the nicotine e-cigarette group smoked fewer cigarettes than any other group. Moreover, participants in this group showed the lowest level of exhaled carbon monoxide (CO) (M = 12.012, S.D. = 8.130), and the lowest level of dependence (M = 3.12, S.D. = 2.29) compared to the nicotine-free e-cigarette and control conditions.

CONCLUSIONS

After 6 months about 20% of the entire sample stopped smoking. Participants who used e-cigarettes with nicotine smoked fewer tobacco cigarettes than any other group after 6 months (p < .020). Our data add to the efficacy and safety of e-cigarettes in helping smokers reducing tobacco consumption and improving pulmonary health status.

A Systematic Literature Review of E-Cigarette-Related Illness and Injury: Not Just for the Respirologist

Following the recent electronic cigarette (e-cigarette) illness outbreak, the current review aimed to collect all related clinical cases for study and analysis and provide a critical synopsis of the proposed injury mechanism. Adhering to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analysis) guidelines, e-cigarette-related clinical cases were identified via Google Scholar and PubMed databases. Additionally, references of published case reports and previous review papers were manually searched, revealing 159 publications presenting e-cigarette-related case reports and 19 reports by the Centers for Disease Control and Prevention. 238 individual cases were identified; 53% traumatic injuries due to e-cigarette explosion or self-combustion, 24% respiratory cases, and 12% poisonings. Additional cases pertained to oral, cardiovascular, immunologic, hematologic, allergic reactions, infant complications, and altered medication levels. Case reports were mainly published between 2016-2019 (78%). The oldest case, a lipoid pneumonia, was published in 2012. The current review showed that e-cigarette-related health effects extend beyond the acute lung injury syndrome, including traumatic, thermal injuries and acute intoxications. Physicians should be aware of the distinct clinical presentations and be trained to respond and treat effectively. Regulators and public health authorities should address the regulatory gap regarding electronic nicotine delivery systems (ENDS) and novel tobacco products.

Role of the mucins in pathogenesis of COPD: implications for therapy

Introduction: Evidence accumulated in the last decade has started to reveal the enormous complexity in the expression, interactions and functions of the large number of different mucins present in the different compartments of the human lower airways. This occurs both in normal subjects and in COPD patients in different clinical phases and stages of severity.Areas covered: We review the known physiological mechanisms that regulate mucin production in human lower airways of normal subjects, the changes in mucin synthesis/secretion in COPD patients and the clinical efficacy of drugs that modulate mucin synthesis/secretion.Expert opinion: It is evident that the old simplistic concept that mucus hypersecretion in COPD patients is associated with negative clinical outcomes is not valid and that the therapeutic potential of 'mucolytic drugs' is under-appreciated due to the complexity of the associated molecular network(s). Likewise, our current knowledge of the effects of the drugs already available on the market that target mucin synthesis/secretion/structure in the lower airways is extremely limited and often indirect and more well-controlled clinical trials are needed in this area.

ERS International Congress, Madrid, 2019: highlights from the Basic and Translational Science Assembly

In this review, the Basic and Translational Sciences Assembly of the European Respiratory Society (ERS) provides an overview of the 2019 ERS International Congress highlights. In particular, we discuss how the novel and very promising technology of single cell sequencing has led to the development of a comprehensive map of the human lung, the lung cell atlas, including the discovery of novel cell types and new insights into cellular trajectories in lung health and disease. Further, we summarise recent insights in the field of respiratory infections, which can aid in a better understanding of the molecular mechanisms underlying these infections in order to develop novel vaccines and improved treatment options. Novel concepts delineating the early origins of lung disease are focused on the effects of pre- and post-natal exposures on neonatal lung development and long-term lung health. Moreover, we discuss how these early life exposures can affect the lung microbiome and respiratory infections. In addition, the importance of metabolomics and mitochondrial function analysis to subphenotype chronic lung disease patients according to their metabolic program is described. Finally, basic and translational respiratory science is rapidly moving forward and this will be beneficial for an advanced molecular understanding of the mechanisms underlying a variety of lung diseases. In the long-term this will aid in the development of novel therapeutic targeting strategies in the field of respiratory medicine.

Highlights of basic and translational science presented at #ERSCongress 2019 summarising latest research on the lung cell atlas, lung infections, early origins of lung disease and the importance of metabolic alterations in the lunghttp://bit.ly/2UbdBs4

E-cigarettes: Effects in phagocytosis and cytokines response against Mycobacterium tuberculosis

Cigarette smoking and tuberculosis are a significant cause of death worldwide. Several epidemiological studies have demonstrated cigarette smoking is a risk factor for tuberculosis. Electronic cigarettes have recently appeared as a healthier alternative to conventional smoking, although their impact in tuberculosis is not well understood. The aim of this study was to explore the effect of electronic cigarettes in phagocytosis of Mycobacterium tuberculosis and cytokines production. In vitro infection was carried out by exposing THP-1 macrophages to four electronic vapor extracts and the intracellular burden of M. tuberculosis was determined. The percentage of infection was evaluated by confocal microscopy and the cytokine production by Luminex. A reduction of intracellular M. tuberculosis burden in THP-1 macrophages was found after its exposure to electronic vapor extract; the same trend was observed by confocal microscopy when Mycobacterium bovis BCG-GFP strain was used. Electronic cigarettes stimulate a pro-inflammatory cytokine response. We conclude that electronic cigarettes impair the phagocytic function and the cytokine response to M. tuberculosis.

Short-term E-cigarette toxicity effects on brain cognitive memory functions and inflammatory responses in mice

Exposure to cigarette smoke (CS) is associated with an increased risk of several neurological diseases such as stroke, Alzheimer's disease, and dementia. At present, commercialization of E-cigarettes (ECs) is increasing, and they are advertised as a less harmful nicotine-delivery system. There are, however, limited studies regarding the neurotoxicity effects of ECs on the brain, which remains a subject of debate. In the present study, we aimed to evaluate the in vivo effects of short-term EC vapor exposure on the brain and compare them with the effects of cigarette smoke (CS). BALB/c mice were exposed to air, CS, and EC for 14 days. We then assessed the inflammatory responses, oxidative stress, and cognitive functions of the mice by using maze tests. Cognitive spatial tests showed that the mice exposed to CS and ECs had delayed time in finding food rewards. EC exposure demonstrated no improvement in spatial memory learning to find the food reward on the next day. This implies that CS and EC exposure possibly causes damage to the olfactory system. Notably, EC exposure potentially causes abnormalities in mice memory functions. Histological staining of the cerebral cortex of mice brain in the EC-exposed group demonstrated inflammatory responses such as necrosis and cytoplasm vacuolization. Immunohistochemical staining revealed high expression of proinflammatory cytokine TNF-α in both the EC- and CS-exposed groups. Hence, we conclude that ECs share similar toxicity profiles as CS, which potentially negatively impact brain function.

Association of E-Cigarette Use With Respiratory Disease Among Adults: A Longitudinal Analysis

INTRODUCTION

E-cigarettes deliver an aerosol of nicotine by heating a liquid and are promoted as an alternative to combustible tobacco. This study determines the longitudinal associations between e-cigarette use and respiratory disease controlling for combustible tobacco use.

METHODS

This was a longitudinal analysis of the adult Population Assessment of Tobacco and Health Waves 1, 2, and 3. Multivariable logistic regression was performed to determine the associations between e-cigarette use and respiratory disease, controlling for combustible tobacco smoking, demographic, and clinical variables. Data were collected in 2013-2016 and analyzed in 2018-2019.

RESULTS

Among people who did not report respiratory disease (chronic obstructive pulmonary disease, chronic bronchitis, emphysema, or asthma) at Wave 1, the longitudinal analysis revealed statistically significant associations between former e-cigarette use (AOR=1.31, 95% CI=1.07, 1.60) and current e-cigarette use (AOR=1.29, 95% CI=1.03, 1.61) at Wave 1 and having incident respiratory disease at Waves 2 or 3, controlling for combustible tobacco smoking, demographic, and clinical variables. Current combustible tobacco smoking (AOR=2.56, 95% CI=1.92, 3.41) was also significantly associated with having respiratory disease at Waves 2 or 3. Odds of developing respiratory disease for a current dual user (e-cigarette and all combustible tobacco) were 3.30 compared with a never smoker who never used e-cigarettes. Analysis controlling for cigarette smoking alone yielded similar results.

CONCLUSIONS

Use of e-cigarettes is an independent risk factor for respiratory disease in addition to combustible tobacco smoking. Dual use, the most common use pattern, is riskier than using either product alone.

Flavored e-liquids increase cytoplasmic Ca2+ levels in airway epithelia

E-cigarettes are noncombustible, electronic nicotine-delivery devices that aerosolize an e-liquid, i.e., nicotine, in a propylene glycol-vegetable glycerin vehicle that also contains flavors. While the effects of nicotine are relatively well understood, more information regarding the potential biological effects of the other e-liquid constituents is needed. This is a serious concern, because e-liquids are available in >7,000 distinct flavors. We previously demonstrated that many e-liquids affect cell growth/viability through an unknown mechanism. Since Ca2+ is a ubiquitous second messenger that regulates cell growth, we characterized the effects of e-liquids on cellular Ca2+ homeostasis. To better understand the extent of this effect, we screened e-liquids for their ability to alter cytosolic Ca2+ levels and found that 42 of 100 flavored e-liquids elicited a cellular Ca2+ response. Banana Pudding (BP) e-liquid, a representative e-liquid from this group, caused phospholipase C activation, endoplasmic reticulum (ER) Ca2+ release, store-operated Ca2+ entry (SOCE), and protein kinase C (PKCα) phosphorylation. However, longer exposures to BP e-liquid depleted ER Ca2+ stores and inhibited SOCE, suggesting that this e-liquid may alter Ca2+ homeostasis by short- and long-term mechanisms. Since dysregulation of Ca2+ signaling can cause chronic inflammation, ER stress, and abnormal cell growth, flavored e-cigarette products that can elicit cell Ca2+ responses should be further screened for potential toxicity.

The Evolving Landscape of e-Cigarettes: A Systematic Review of Recent Evidence

Smoking continues to be a burden to economies and health-care systems across the world. One proposed solution to the problem has been e-cigarettes; however, because they are a relatively new product in the market, little is known about their potential health impacts. Furthermore, e-cigarettes continue to evolve at a rapid rate, making it necessary to regularly review and summarize available studies. Although e-cigarettes are marketed as a smoking cessation tool by some manufacturers, the reality is that many nonsmokers, including youth, are using them. This review focuses on two major demographic groups (smokers and nonsmokers) and evaluates the most recent data (early 2017 to mid 2019) regarding the potential health effects of e-cigarettes. We assessed peer-reviewed studies on the health impacts of e-cigarettes, with a particular focus on common questions asked by policy makers, clinicians, and scientists: (1) What are the effects of e-cigarettes compared with air/not smoking?; (2) Is there any direct evidence of harm or benefit to humans?; (3) Is there a risk from secondhand exposure?; (4) What are the risks and/or benefits of e-cigarettes compared with tobacco cigarette use?; (5) Are there risks or benefits to specific populations (eg, people with COPD or asthma, pregnant women [and their offspring])?; (6) What are the effects of flavoring chemicals?; (7) What are the effects of including nicotine in e-liquids?; (8) How often is nicotine concentration labeling incorrect?; and (9) What are the risks when e-cigarettes explode?

A Case Series of Vaping-Associated Lung Injury Requiring Mechanical Ventilation

OBJECTIVES

Vaping-associated lung injury has rapidly become a nationwide epidemic and a threat to public health. In this case series, we describe unique clinical features of severe vaping-associated lung injury, defined as respiratory failure due to vaping that requires mechanical ventilation.

DATA SOURCES

Clinical observation of four patients.

STUDY SELECTION

Case series.

DATA EXTRACTION

Data and images were extract from medical records after approval was obtained from the institutional review board.

DATA SYNTHESIS

Four patients were admitted to the ICU with severe manifestation of vaping-associated lung injury. Although every case required mechanical ventilatory support (venovenous extracorporeal membrane oxygenation in one patient), all patients survived and were discharged without supplemental oxygen. Systemic corticosteroids were administered in three patients and N-acetyl cysteine in one. A postdischarge pulmonary function test in one patient was normal except for mildly decreased diffusing capacity.

CONCLUSIONS

Based on our experience, prognosis of severe vaping-associated lung injury appears favorable with aggressive supportive care, although there is evidence from existing literature that mortality rate might rise with increasing disease severity. Underlying mechanism of lung injury might be similar between vaping-associated lung injury and amiodarone pneumonitis. Foamy or lipid-laden macrophages, seen in both conditions, might be a marker of cytotoxicity from substances contained in e-cigarettes, such as vitamin E acetate. Systemic corticosteroids, and possibly N-acetyl cysteine, could be considered as therapeutic adjuncts in vaping-associated lung injury. Serial pulmonary function tests should be obtained in these patients to monitor for potential long-term complications. The primary limitations of this case series are its small sample and lack of longitudinal follow-up data.

A pilot study to examine the acceptability and health effects of electronic cigarettes in HIV-positive smokers

INTRODUCTION

Some HIV-positive smokers report ambivalence about quitting. Switching to electronic cigarettes (ECs) may be a viable option to reduce the negative health effects for smokers who are unable or unwilling to quit smoking combustible cigarettes (CCs). This study examined the acceptability and health-related effects of ECs in HIV-positive smokers who were not seeking smoking cessation treatment.

METHODS

HIV-positive smokers (N = 19) were enrolled and followed for 12 weeks. Cartridge-based ECs were provided at baseline, and E-liquid was provided weekly for 8 weeks. At baseline, weeks 1-8, and week 12, EC and CC use, cardiopulmonary function, respiratory symptoms, and carbon monoxide (CO) levels were measured.

RESULTS

At week 8, cigarettes per day (CPD) were reduced by more than 80%, with reduction maintained at week 12 (p's < .001). Cigarette dependence scores were 40% lower at week 8 than at baseline (p <  .001). Seven (36.8%) participants reported transitioning completely from CCs to ECs. Mean CO decreased significantly from BL to week 8 (p < .05) and remained significantly lower at week 12 (p <  .001). Intention to quit increased significantly over time.

CONCLUSIONS

Switching from CCs to ECs in HIV-positive smokers who are not ready to quit smoking in the next 30 days appears to be feasible. Beneficial effects were seen, such as reduced CPD, reduced CO and CC dependence, and increased motivation to quit. ECs may be promising as a harm reduction approach among HIV-positive smokers who are unable or unwilling to quit smoking.

Electronic cigarette vapour increases virulence and inflammatory potential of respiratory pathogens

INTRODUCTION

Bacteria have been extensively implicated in the development of smoking related diseases, such as COPD, by either direct infection or bacteria-mediated inflammation. In response to the health risks associated with tobacco exposure, the use of electronic cigarettes (e-cigs) has increased. This study compared the effect of e-cig vapour (ECV) and cigarette smoke (CSE) on the virulence and inflammatory potential of key lung pathogens (Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus and Pseudomonas aeruginosa).

METHODS

Biofilm formation, virulence in the Galleria mellonella infection model, antibiotic susceptibility and IL-8/TNF-α production in A549 cells, were compared between bacteria exposed to ECV, CSE and non-exposed bacteria.

RESULTS

Statistically significant increases in biofilm and cytokine secretion were observed following bacterial exposure to either ECV or CSE, compared to non-exposed bacteria; the effect of exposure to ECV on bacterial phenotype and virulence was comparable, and in some cases greater, than that observed following CSE exposure. Treatment of A549 cells with cell signaling pathway inhibitors prior to infection, did not suggest that alternative signaling pathways were being activated following exposure of bacteria to either ECV or CSE.

CONCLUSIONS

These findings therefore suggest that ECV and CSE can induce changes in phenotype and virulence of key lung pathogens, which may increase bacterial persistence and inflammatory potential.

Biomarkers of Exposure and Effect in the Lungs of Smokers, Nonsmokers, and Electronic Cigarette Users

BACKGROUND

Nicotine-containing electronic cigarette (e-cig) use has become widespread. However, understanding the biological impact of e-cigs compared with smoking on the lung is needed. There are major gaps in knowledge for chronic effects and for an etiology to recent acute lung toxicity leading to death among vapers.

METHODS

We conducted bronchoscopies in a cross-sectional study of 73 subjects (42 never-smokers, 15 e-cig users, and 16 smokers). Using bronchoalveolar lavage and brushings, we examined lung inflammation by cell counts, cytokines, genome-wide gene expression, and DNA methylation.

RESULTS

There were statistically significant differences among never-smokers, e-cig users, and smokers for inflammatory cell counts and cytokines (FDR q < 0.1). The e-cig users had values intermediate between smokers and never-smokers, with levels for most of the biomarkers more similar to never-smokers. For differential gene expression and DNA methylation, e-cig users also more like never-smokers; many of these genes corresponded to smoking-related pathways, including those for xenobiotic metabolism, aryl hydrocarbon receptor signaling, and oxidative stress. Differentially methylated genes were correlated with changes in gene expression, providing evidence for biological effects of the methylation associations.

CONCLUSIONS

These data indicate that e-cigs are associated with less toxicity than cigarettes for smoking-related pathways. What is unknown may be unique effects for e-cigs not measured herein, and a comparison of smokers completely switching to e-cigs compared with former smokers. Clinical trials for smokers switching to e-cigs who undergo serial bronchoscopy and larger cross-sectional studies of former smokers with and without e-cig use, and for e-cigs who relapse back to smoking, are needed.

IMPACT

These data can be used for product regulation and for informing tobacco users considering or using e-cigs. What is unknown may be unique effects for e-cigs not measured herein, and clinical trials with serial bronchoscopy underway can demonstrate a direct relationship for changes in lung biomarkers.

Chronic E-Cigarette Use Increases Neutrophil Elastase and Matrix Metalloprotease Levels in the Lung

Rationale: Proteolysis is a key aspect of the lung's innate immune system. Proteases, including neutrophil elastase and MMPs (matrix metalloproteases), modulate cell signaling, inflammation, tissue remodeling, and leukocyte recruitment via cleavage of their target proteins. Excessive proteolysis occurs with chronic tobacco use and is causative for bronchiectasis and emphysema. The effect of e-cigarettes (vaping) on proteolysis is unknown.

Objectives: We used protease levels as biomarkers of harm to determine the impact of vaping on the lung.

Methods: We performed research bronchoscopies on healthy nonsmokers, cigarette smokers, and e-cigarette users (vapers), and determined protease levels in BAL. In parallel, we studied the effects of e-cigarette components on protease secretion in isolated human blood neutrophils and BAL-derived macrophages. We also analyzed the nicotine concentration in induced sputum and BAL.

Measurements and Main Results: Neutrophil elastase, MMP-2, and MMP-9 activities and protein levels were equally elevated in both vapers' and smokers' BAL relative to nonsmokers. In contrast, antiprotease levels were unchanged. We also found that exposure of isolated neutrophils and macrophages to nicotine elicited dose-dependent increases in protease release. After vaping, measurable levels of nicotine were detectable in sputum and BAL, which corresponded to the half-maximal effective concentration values for protease release seen in immune cells.

Conclusions: We conclude that vaping induces nicotine-dependent protease release from resident pulmonary immune cells. Thus, chronic vaping disrupts the protease-antiprotease balance by increasing proteolysis in lung, which may place vapers at risk of developing chronic lung disease. These data indicate that vaping may not be safer than tobacco smoking.