Counseling patients with asthma and allergy about electronic cigarettes: an evidence-based approach

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.

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.

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.

Factors associated with electronic cigarette use among adolescents asthma in the Republic Of Korea

OBJECTIVES

Despite the rapid increase in electronic cigarette (e-cigarette) smoking, little is known about the factors associated with their use, particularly in adolescents with asthma. Our study investigated the prevalence of, and factors associated with asthma.

METHODS

We analyzed data from the Korean Youth Risk Behavior Web-based Survey of 44,479 adolescents with physician-diagnosed asthma and 445,692 subjects without asthma. Sociodemographic factors, psychosocial factors, and e-cigarette smoking patterns were investigated by self-report questionnaires. Multiple logistic regression was used to investigate the factors associated with ever or current e-cigarette risks in adolescents with asthma, with adjustment for confounding factors.

RESULTS

Significantly more subjects had a smoking habit in the asthma group than in the non-asthma group. Among the adolescents with asthma, 4,420 (9.9%) smoked e-cigarettes (ever-users), and 1,962 (4.4%) smoked e-cigarettes within the last 30 days (current users). Multiple logistic regression showed that both ever and current e-cigarette use were significantly associated with male gender, higher family income, residence in an urban area, alcohol drinking, substance use experience, sexual experience, and friends' smoking. Current e-cigarette use was also significantly associated with high caffeine intake, no regular exercise, and experience of violence in adolescents with asthma.

CONCLUSIONS

E-cigarette smoking behavior was significantly more frequent in adolescents with asthma than in those without asthma, and multiple psychosocial factors were associated with e-cigarette smoking. Our results could inform e-smoking control programs and help identify adolescents with asthma at high risk of e-cigarette smoking, to ultimately prevent and reduce this behavior.

Electronic cigarette use among adults with asthma: 2014-2017 National Health Interview Survey

BACKGROUND

Electronic cigarette (e-cigarette) use has increased dramatically in the United States among adults and adolescents. Patients with asthma may be most vulnerable to the chemical components of e-cigarettes as they may be a potential asthma trigger.

OBJECTIVE

To assess the prevalence of e-cigarette use among adult asthmatics and to evaluate the factors associated with e-cigarette use.

METHODS

This was a retrospective, cross-sectional study that used data from the 2014-2017 National Health Interview Survey (NHIS) database. The study sample included current asthmatics who were 18-85 years old. The outcome variable was ever use of an e-cigarette (Yes/No). The Andersen Behavioral Model of Health Services Utilization was used to identify independent variables with the potential to influence the patient's decision to try e-cigarettes. Descriptive statistics were used to describe the sample. Factors associated with e-cigarette use were assessed using logistic regression. All analyses were stratified by age group. Appropriate survey weights were used to account for the complex survey design.

RESULTS

The study sample included 10,578 adults with current asthma and about 18% of the sample had ever tried an e-cigarette. About 20% of males and 20% of non-Hispanic Whites reported ever trying an e-cigarette. From 2014 to 2017, the e-cigarette use among the 18-24 year old age group increased the most from 20.3% to 29.1%. Current smokers were more likely to have tried e-cigarettes than former/never smokers (18-24 years OR: 11.5 CI: 7.4-18.0). This trend was significant among all age groups. Non-Hispanic Blacks were less likely to have tried e-cigarettes than non-Hispanic Whites (50-64 years OR: 0.34 CI: 0.22-0.52).

CONCLUSION

The prevalence of e-cigarette use among adult asthmatics has continued to increase over time. Smoking status was the most consistent predictor of e-cigarette use among all age groups in this asthmatic population.

Inhalation of electronic cigarette aerosol induces reflex bronchoconstriction by activation of vagal bronchopulmonary C-fibers

The electronic cigarette (e-cig) has been suggested as a safer alternative to tobacco cigarettes. However, the health effects of e-cigs on the airways have not been fully investigated. Nicotine, the primary chemical constituent of the e-cig aerosol, has been shown to stimulate vagal bronchopulmonary C-fiber sensory nerves, which upon activation can elicit vigorous pulmonary defense reflexes, including airway constriction. In this study, we investigated the bronchomotor response to e-cig inhalation challenge in anesthetized guinea pigs and the mechanisms involved in regulating these responses. Our results showed that delivery of a single puff of e-cig aerosol into the lung triggered immediately a transient bronchoconstriction that sustained for >2 min. The increase in airway resistance was almost completely abolished by a pretreatment with either intravenous injection of atropine or inhalation of aerosolized lidocaine, suggesting that the bronchoconstriction was elicited by cholinergic reflex mechanism and stimulation of airway sensory nerves was probably involved. Indeed, electrophysiological recording further confirmed that inhalation of e-cig aerosol exerted a pronounced stimulatory effect on vagal bronchopulmonary C-fibers. These effects on airway resistance and bronchopulmonary C-fiber activity were absent when the e-cig aerosol containing zero nicotine was inhaled, indicating a critical role of nicotine. Furthermore, a pretreatment with nicotinic acetylcholine receptor antagonists by inhalation completely prevented the airway constriction evoked by e-cig aerosol inhalation. In conclusion, inhalation of a single puff of e-cig aerosol caused a transient bronchoconstriction that was mediated through cholinergic reflex and triggered by a stimulatory effect of nicotine on vagal bronchopulmonary C-fiber afferents.

Physicochemical studies of direct interactions between lung surfactant and components of electronic cigarettes liquid mixtures

Direct physicochemical interactions between the major components of electronic cigarette liquids (e-liquids): glycerol (VG) and propylene glycol (PG), and lung surfactant (LS) were studied by determining the dynamic surface tension under a simulated breathing cycle using drop shape method. The studies were performed for a wide range of concentrations based on estimated doses of e-liquid aerosols (up to 2500 × the expected nominal concentrations) and for various VG/PG ratios. The results are discussed as relationships among mean surface tension, surface tension amplitude, and surface rheological properties (dilatational elasticity and viscosity) versus concentration and composition of e-liquid. The results showed that high local concentrations (>200 × higher than the estimated average dose after a single puffing session) may induce measurable changes in biophysical activity of LS; however, only ultra-high e-liquid concentrations inactivated the surfactant. Physiochemical characterization of e-liquids provide additional insights for the safety assessment of electronic nicotine delivery systems (ENDS).

Harm Minimization and Tobacco Control: Reframing Societal Views of Nicotine Use to Rapidly Save Lives

Inhalation of the toxic smoke produced by combusting tobacco products, primarily cigarettes, is the overwhelming cause of tobacco-related disease and death in the United States and globally. A diverse class of alternative nicotine delivery systems (ANDS) has recently been developed that do not combust tobacco and are substantially less harmful than cigarettes. ANDS have the potential to disrupt the 120-year dominance of the cigarette and challenge the field on how the tobacco pandemic could be reversed if nicotine is decoupled from lethal inhaled smoke. ANDS may provide a means to compete with, and even replace, combusted cigarette use, saving more lives more rapidly than previously possible. On the basis of the scientific evidence on ANDS, we explore benefits and harms to public health to guide practice, policy, and regulation. A reframing of societal nicotine use through the lens of harm minimization is an extraordinary opportunity to enhance the impact of tobacco control efforts.

An approach to testing undiluted e-cigarette aerosol in vitro using 3D reconstituted human airway epithelium

The data presented here show that to provide an estimate of the relative cytotoxicity and therefore potency of e-cigarettes, undiluted aerosol techniques can be used. With the emergence of electronic nicotine delivery systems, fit-for-purpose in vitro screening methods are required. Reconstituted 3D human airway epithelium, was exposed to undiluted aerosols at the air-liquid interface, using a Vitrocell VC 10. TEER, cilia beat frequency and cytotoxic responses were assessed. Using two smoking regimes (ISO and HCI) a 3R4F reference cigarette, produced IC₅₀s of 5.2 and 2.1 min, 1458 ng/mL and 1640 ng/mL nicotine respectively. Using an open tank e-cigarette device, a full cytotoxicity dose-response curve was obtained giving an IC₅₀ of 30 min with corresponding nicotine of 10,957 ng/mL, 6-14 times less cytotoxic than cigarette smoke. A commonly used e-liquid flavourant cinnamaldehyde and known skin sensitizer was added to the standard e-liquid formulation and used as an aerosolised positive control, at 0.1, 0.025, 0.01 and 0%, demonstrating a full dose response. The delivery of undiluted aerosols in vitro has resulted in increased method sensitivity, throughput and quantitative e-cigarette comparisons. A positive control aerosol generated from a 'safe' e-liquid benchmark can inform risk assessments on supportable levels of flavour ingredients.

Evaluation of genotoxic effects in Brazilian agricultural workers exposed to pesticides and cigarette smoke using machine-learning algorithms

Monitoring exposure to xenobiotics by biomarker analyses, such as a micronucleus assay, is extremely important for the precocious detection and prevention of diseases, such as oral cancer. The aim of this study was to evaluate genotoxic effects in rural workers who were exposed to cigarette smoke and/or pesticides and to identify possible classification patterns in the exposure groups. The sample included 120 participants of both sexes aged between 18 and 39, who were divided into the following four groups: control group (CG), smoking group (SG), pesticide group (PG), and smoking + pesticide group (SPG). Their oral mucosa cells were stained with Giemsa for cytogenetic analysis. The total numbers of nuclear abnormalities (CG = 27.16 ± 14.32, SG = 118.23 ± 74.78, PG = 184.23 ± 52.31, and SPG = 191.53 ± 66.94) and micronuclei (CG = 1.46 ± 1.40, SG = 12.20 ± 10.79, PG = 21.60 ± 8.24, and SPG = 20.26 ± 12.76) were higher (p < 0.05) in the three exposed groups compared to the GC. In this study, we considered several different classification algorithms (the artificial neural network, K-nearest neighbors, support vector machine, and optimum path forest). All of the algorithms displayed good classification (accuracy > 80%) when using dataset2 (without the redundant exposure type SPG). It is clear that the data form a robust pattern and that classifiers could be successfully trained on small datasets from the exposure groups. In conclusion, exposing agricultural workers to pesticides and/or tobacco had genotoxic potential, but concomitant exposure to xenobiotics did not lead to additive or potentiating effects.

Electronic Cigarettes: Their Constituents and Potential Links to Asthma

PURPOSE OF REVIEW

Vaping is gaining popularity in the USA, particularly among teens and young adults. While e-cigs are commonly represented as safer alternatives to tobacco cigarettes, little is known regarding the health effects of their short- or long-term use, especially in individuals with pre-existing respiratory diseases such as asthma. Flavored e-cig liquids (e-liquids) and e-cig aerosols contain airway irritants and toxicants that have been implicated in the pathogenesis and worsening of lung diseases. In this review, we will summarize existing data on potential health effects of components present in e-cig aerosols, such as propylene glycol, vegetable glycerin, nicotine, and flavorings, and discuss their relevance in the context of asthma.

RECENT FINDINGS

Recent survey data indicate that adolescents with asthma had a higher prevalence of current e-cig use (12.4%) compared to their non-asthmatics peers (10.2%) and conveyed positive beliefs about tobacco products, especially e-cigs. Similarly, a study conducted among high school students from Ontario, Canada, indicated a greater likelihood of e-cig use in asthmatics as compared to their non-asthmatic peers. Availability of different flavorings is often cited as the main reason among youth/adolescents for trying e-cigs or switching from cigarettes to e-cigs. Occupational inhalation of some common food-safe flavoring agents is reported to cause occupational asthma and worsen asthmatic symptoms. Moreover, workplace inhalation exposures to the flavoring agent diacetyl have caused irreversible obstructive airway disease in healthy workers. Additionally, recent studies report that thermal decomposition of propylene glycol (PG) and vegetable glycerin (VG), the base constituents of e-liquids, produces reactive carbonyls, including acrolein, formaldehyde, and acetaldehyde, which have known respiratory toxicities. Furthermore, recent nicotine studies in rodents reveal that prenatal nicotine exposures lead to epigenetic reprogramming in the offspring, abnormal lung development, and multigenerational transmission of asthmatic-like symptoms. Comparisons of the toxicity and health effects of e-cigs and conventional cigarettes often focus on toxicants known to be present in cigarette smoke (CS) (i.e., formaldehyde, nitrosamines, etc.), as well as smoking-associated clinical endpoints, such as cancer, bronchitis, and chronic obstructive pulmonary disease (COPD). However, this approach disregards potential toxicity of components unique to flavored e-cigs, such as PG, VG, and the many different flavoring chemicals, which likely induce respiratory effects not usually observed in cigarette smokers.

Strategies to alter the natural history of childhood asthma

PURPOSE OF REVIEW

Asthma exhibits significant heterogeneity in occurrence and severity over the lifespan. Our goal is to discuss recent evidence regarding determinants of the natural history of asthma during childhood, and review the rationale behind and status of major efforts to alter its course.

RECENT FINDINGS

Variations in microbial exposures are associated with risk of allergic disease, and the use of bacterial lysates may be a promising preventive strategy. Exposure to air pollution appears to be particularly damaging in prenatal and early life, and interventions to reduce pollution are feasible and result in clinical benefit. E-cigarette use may have a role in harm reduction for conventional cigarette smokers with asthma, but has undefined short-term and long-term effects that must be clarified. Vitamin D insufficiency over the first several years of life is associated with risk of asthma, and vitamin D supplementation reduces the risk of severe exacerbations.

SUMMARY

The identification of risk factors for asthma occurrence, persistence and severity will continue to guide efforts to alter the natural history of the disease. We have reviewed several promising strategies that are currently under investigation. Vitamin D supplementation and air pollution reduction have been shown to be effective strategies and warrant increased investigation and implementation.

Overview of Electronic Nicotine Delivery Systems: A Systematic Review

CONTEXT

Rapid developments in e-cigarettes, or electronic nicotine delivery systems (ENDS), and the evolution of the overall tobacco product marketplace warrant frequent evaluation of the published literature. The purpose of this article is to report updated findings from a comprehensive review of the published scientific literature on ENDS.

EVIDENCE ACQUISITION

The authors conducted a systematic review of published empirical research literature on ENDS through May 31, 2016, using a detailed search strategy in the PubMed electronic database, expert review, and additional targeted searches. Included studies presented empirical findings and were coded to at least one of nine topics: (1) Product Features; (2) Health Effects; (3) Consumer Perceptions; (4) Patterns of Use; (5) Potential to Induce Dependence; (6) Smoking Cessation; (7) Marketing and Communication; (8) Sales; and (9) Policies; reviews and commentaries were excluded. Data from included studies were extracted by multiple coders (October 2015 to August 2016) into a standardized form and synthesized qualitatively by topic.

EVIDENCE SYNTHESIS

There were 687 articles included in this systematic review. The majority of studies assessed patterns of ENDS use and consumer perceptions of ENDS, followed by studies examining health effects of vaping and product features.

CONCLUSIONS

Studies indicate that ENDS are increasing in use, particularly among current smokers, pose substantially less harm to smokers than cigarettes, are being used to reduce/quit smoking, and are widely available. More longitudinal studies and controlled trials are needed to evaluate the impact of ENDS on population-level tobacco use and determine the health effects of longer-term vaping.

Beliefs, Practices, and Self-efficacy of US Physicians Regarding Smoking Cessation and Electronic Cigarettes: A National Survey

INTRODUCTION

We sought to assess physician knowledge/beliefs, self-efficacy, and experience/practice patterns surrounding smoking cessation and electronic cigarettes.

METHODS

An eight-page survey sent via US Postal service. The initial invitation included a $10 cash incentive and up to three invitations were sent. Fifteen hundred US physicians were identified with equal representation from primary care physicians (internal medicine and family practice), surgical care physicians (general surgeons and anesthesiologists), and pulmonologists.

RESULTS

Two hundred fourteen were not included in the analysis (183 non-deliverable, one deceased, 30 not practicing). 561/1286 (44%) remaining surveys were returned for analysis. Greater than 90% agreed that advising and assisting with smoking cessation is their responsibility; 86% advise and 65% assist their patients with smoking cessation more than 75% of the time. Approximately two-thirds of respondents report that their patients ask them about electronic cigarettes at least some of the time (≥25%); 58.4% report that they ask their patients about electronic cigarette use at least some of the time. Overall, 37.9% have at some point recommended electronic cigarettes to their patients that smoke, with 11.5% reporting recommending them at least 25% of the time. Surgical care providers appear less confident and less self-efficacious with smoking cessation, as well as with electronic cigarettes and appear less likely to endorse use of electronic cigarettes.

DISCUSSION

US physicians are frequently discussing electronic cigarettes in a clinical context and a substantial proportion of US physicians have recommended electronic cigarettes to their patients.

IMPLICATIONS

This study documents several important previously poorly characterized aspects of the role of electronic cigarettes in clinical care. The majority of US physicians are discussing electronic cigarettes in clinical contexts and a substantial proportion of US physicians have recommended electronic cigarettes to their patients. The extent of physician engagement on the topic of electronic cigarettes should be met with increased efforts to better characterize electronic cigarettes' appropriate role in smoking cessation and reduction.

A framework for in vitro systems toxicology assessment of e-liquids

Various electronic nicotine delivery systems (ENDS), of which electronic cigarettes (e-cigs) are the most recognized prototype, have been quickly gaining ground on conventional cigarettes because they are perceived as less harmful. Research assessing the potential effects of ENDS exposure in humans is currently limited and inconclusive. New products are emerging with numerous variations in designs and performance parameters within and across brands. Acknowledging these challenges, we present here a proposed framework for an in vitro systems toxicology assessment of e-liquids and their aerosols, intended to complement the battery of assays for standard toxicity assessments. The proposed framework utilizes high-throughput toxicity assessments of e-liquids and their aerosols, in which the device-to-device variability is minimized, and a systems-level investigation of the cellular mechanisms of toxicity is an integral part. An analytical chemistry investigation is also included as a part of the framework to provide accurate and reliable chemistry data solidifying the toxicological assessment. In its simplest form, the framework comprises of three main layers: (1) high-throughput toxicity screening of e-liquids using primary human cell culture systems; (2) toxicity-related mechanistic assessment of selected e-liquids, and (3) toxicity-related mechanistic assessment of their aerosols using organotypic air-liquid interface airway culture systems. A systems toxicology assessment approach is leveraged to enable in-depth analyses of the toxicity-related cellular mechanisms of e-liquids and their aerosols. We present example use cases to demonstrate the suitability of the framework for a robust in vitro assessment of e-liquids and their aerosols.

Knowledge and Perceptions about Nicotine, Nicotine Replacement Therapies and Electronic Cigarettes among Healthcare Professionals in Greece

Introduction. The purpose of this study was to evaluate the knowledge and perceptions of Greek healthcare professionals about nicotine, nicotine replacement therapies and electronic cigarettes. Methods. An online survey was performed, in which physicians and nurses working in private and public healthcare sectors in Athens-Greece were asked to participate through email invitations. A knowledge score was calculated by scoring the correct answers to specific questions with 1 point. Results. A total of 262 healthcare professionals were included to the analysis. Most had daily contact with smokers in their working environment. About half of them considered that nicotine has an extremely or very important contribution to smoking-related disease. More than 30% considered nicotine replacement therapies equally or more addictive than smoking, 76.7% overestimated their smoking cessation efficacy and only 21.0% would recommend them as long-term smoking substitutes. For electronic cigarettes, 45.0% considered them equally or more addictive than smoking and 24.4% equally or more harmful than tobacco cigarettes. Additionally, 35.5% thought they involve combustion while the majority responded that nicotine in electronic cigarettes is synthetically produced. Only 14.5% knew about the pending European regulation, but 33.2% have recommended them to smokers in the past. Still, more than 40% would not recommend electronic cigarettes to smokers unwilling or unable to quit smoking with currently approved medications. Cardiologists and respiratory physicians, who are responsible for smoking cessation therapy in Greece, were even more reluctant to recommend electronic cigarettes to this subpopulation of smokers compared to all other participants. The knowledge score of the whole study sample was 7.7 (SD: 2.4) out of a maximum score of 16. Higher score was associated with specific physician specialties. Conclusions. Greek healthcare professionals appear to overestimate the adverse effects of nicotine, and many would not recommend any nicotine-containing product as a long-term smoking substitute. Additionally, they have poor knowledge about the function and characteristics of electronic cigarettes.