The Effect of Electronic-Cigarette Vaping on Cardiac Function and Angiogenesis in Mice

Acute exposure to electronic cigarette components alters mRNA expression of pre-osteoblasts

The use of traditional nicotine delivery products such as tobacco has long been linked to detrimental health effects. However, little work to date has focused on the emerging market of aerosolized nicotine delivery known as electronic nicotine delivery systems (ENDS) or electronic cigarettes, and their potential for new effects on human health. Challenges studying these devices include heterogeneity in the formulation of the common components of most available ENDS, including nicotine and a carrier (commonly composed of propylene glycol and vegetable glycerin, or PG/VG). In the present study, we report on experiments interrogating the effects of major identified components in e-cigarettes. Specifically, the potential concomitant effects of nicotine and common carrier ingredients in commercial "vape" products are explored in vitro to inform the potential health effects on the craniofacial skeleton through novel vectors as compared to traditional tobacco products. MC3T3-E1 murine pre-osteoblast cells were cultured in vitro with clinically relevant liquid concentrations of nicotine, propylene glycol (PG), vegetable glycerin (VG), Nicotine+PG/VG, and the vape liquid of a commercial product (Juul). Cells were treated acutely for 24 h and RNA-Seq was utilized to determine segregating alteration in mRNA signaling. Influential gene targets identified with sparse partial least squares discriminant analysis (sPLS-DA) implemented in mixOmics were assessed using the PANTHER Classification system for molecular functions, biological processes, cellular components, and pathways of effect. Additional endpoint functional analyses were used to confirm cell cycle changes. The initial excitatory concentration (EC50) studied defined a target concentration of carrier PG/VG liquid that altered the cell cycle of the calvarial cells. Initial sPLS-DA analysis demonstrated the segregation of nicotine and non-nicotine exposures utilized in our in vitro modeling. Pathway analysis suggests a strong influence of nicotine exposures on cellular processes including metabolic processes and response to stimuli including autophagic flux. Further interrogation of the individual treatment conditions demonstrated segregation by treatment modality (Control, Nicotine, Carrier (PG+VG), Nicotine+PG/VG) along three dimensions best characterized by: latent variable 1 (PLSDA-1) showing strong segregation based on nicotine influence on cellular processes associated with cellular adhesion to collagen, osteoblast differentiation, and calcium binding and metabolism; latent variable 2 (PLSDA-2) showing strong segregation of influence based on PG+VG and Control influence on cell migration, survival, and cycle regulation; and latent variable 3 (PLSDA-3) showing strong segregation based on Nicotine and Control exposure influence on cell activity and growth and developmental processes. Further, gene co-expression network analysis implicates targets of the major pathway genes associated with bone growth and development, particularly craniofacial (FGF, Notch, TGFβ, WNT) and analysis of active subnetwork pathways found these additionally overrepresented in the Juul exposure relative to Nicotine+PG/VG. Finally, experimentation confirmed alterations in cell count, and increased evidence of cell stress (markers of autophagy), but no alteration in apoptosis. These data suggest concomitant treatment with Nicotine+PG/VG drives alterations in pre-osteoblast cell cycle signaling, specifically transcriptomic targets related to cell cycle and potentially cell stress. Although we suspected cell stress and well as cytotoxic effects of Nicotine+PG/VG, no great influence on apoptotic factors was observed. Further RNA-Seq analysis allowed for the direct interrogation of molecular targets of major pathways involved in bone and craniofacial development, each demonstrating segregation (altered signaling) due to e-cigarette-type exposure. These data have implications directed toward ENDS formulation as synergistic effects of Nicotine+PG/VG are evidenced here. Thus, future research will continue to interrogate how varied formulation of Nicotine+PG/VG affects overall cell functions in multiple vital systems.

Sensitivity of Mouse Lung Nuclear Receptors to Electronic Cigarette Aerosols and Influence of Sex Differences: A Pilot Study

The emerging concern about chemicals in electronic cigarettes, even those without nicotine, demands the development of advanced criteria for their exposure and risk assessment. This study aims to highlight the sensitivity of lung nuclear receptors (NRs) to electronic cigarette e-liquids, independent of nicotine presence, and the influence of the sex variable on these effects. Adult male and female C57BL/6J mice were exposed to electronic cigarettes with 0%, 3%, and 6% nicotine daily (70 mL, 3.3 s, 1 puff per min/30 min) for 14 days, using the inExpose full body chamber (SCIREQ). Following exposure, lung tissues were harvested, and RNA extracted. The expression of 84 NRs was determined using the RT2 profiler mRNA array (Qiagen). Results exhibit a high sensitivity to e-liquid exposure irrespective of the presence of nicotine, with differential expression of NRs, including one (females) and twenty-four (males) in 0% nicotine groups compared to non-exposed control mice. However, nicotine-dependent results were also significant with seven NRs (females), fifty-three NRs (males) in 3% and twenty-three NRs (female) twenty-nine NRs (male) in 6% nicotine groups, compared to 0% nicotine mice. Sex-specific changes were significant, but sex-related differences were not observed. The study provides a strong rationale for further investigation.

Effects of Short-term Electronic(e)-Cigarette Aerosol Exposure in the Mouse Larynx

OBJECTIVES

The effects of electronic cigarettes (e-cigarettes) on the larynx are relatively unknown. This study examined the short-term effects of e-cigarette inhalation on cellular and inflammatory responses within the mouse laryngeal glottic and subglottic regions after exposure to pod-based devices (JUUL).

METHODS

Male C57BL6/J mice (8-9 weeks) were assigned to control (n = 9), JUUL flavors Mint (JMi; n = 10) or Mango (JMa; n = 10). JUUL mice were exposed to 2 h/day for 1, 5, and 10 days using the inExpose inhalation system. Control mice were in room air. Vocal fold (VF) epithelial thickness, cell proliferation, subglandular area and composition, inflammatory cell infiltration, and surface topography were evaluated in the harvested larynges. Mouse body weight and urinary nicotine biomarkers were also measured. Chemical analysis of JUUL aerosols was conducted using selective ion flow tube mass spectrometry.

RESULTS

JUUL-exposed mice had reduced body weight after day 5. Urinary nicotine biomarker levels indicated successful JUUL exposure and metabolism. Quantitative analysis of JUUL aerosol indicated that chemical constituents differ between JMi and JMa flavors. VF epithelial thickness, cellular proliferation, glandular area, and surface topography remained unchanged after JUUL exposures. Acidic mucus content increased after 1 day of JMi exposure. VF macrophage and T-cell levels slightly increased after 10 days of JMi exposures.

CONCLUSIONS

Short-term e-cigarette exposures cause minimal flavor- and region-specific cellular and inflammatory changes in the mouse larynx. This work provides a foundation for long-term studies to determine if these responses are altered with multiple e-cigarette components and concentrations.

LEVEL OF EVIDENCE

N/A Laryngoscope, 134:1316-1326, 2024.

The Rising Use of E-Cigarettes: Unveiling the Health Risks and Controversies

The use of e-cigarettes has tremendously increased in recent times due to the widespread availability of e-cigarettes in diverse flavors, reduced cost compared to regular cigarettes, and misconception of being comparatively safe, which have led to around 2.55 million US middle and high school students smoking e-cigarettes. These devices use a nicotine-rich liquid, which is aerosolized electronically, producing vapors that may also include hazardous chemicals and heavy metals. E-cigarettes are associated with e-cigarette or vaping-associated lung injury, which presents as an acute respiratory ailment mirroring various pulmonary diseases. Additionally, it causes endothelial dysfunction, alters blood lipid profile by elevating circulating levels of low-density lipoprotein cholesterol, increases sympathetic tone, and is found to correlate with arterial stiffening, hence negatively affecting respiratory, cardiovascular, and overall health. We aim to provide a comprehensive analysis of the data on e-cigarettes and their harmful effects on health in comparison to conventional cigarette use by highlighting the pathophysiology of e-cigarette-induced adverse effects and critically analyzing the data both in favor and against its use. Our review concludes that no matter how much nicotine an e-cigarette contains, evidence shows that using it increases the risk of cardiovascular disease, albeit maybe not as much as smoking regular tobacco. Nonetheless, it is crucial to note that the long-term effects of e-cigarette usage are still not fully understood, and existing data have provided opposing viewpoints.

E-cigarette exposure causes early pro-atherogenic changes in an inducible murine model of atherosclerosis

Introduction: Evidence suggests that e-cigarette use (vaping) increases cardiovascular disease risk, but decades are needed before people who vape would develop pathology. Thus, murine models of atherosclerosis can be utilized as tools to understand disease susceptibility, risk and pathogenesis. Moreover, there is a poor understanding of how risk factors for atherosclerosis (i.e., hyperlipidemia, high-fat diet) intersect with vaping to promote disease risk. Herein, we evaluated whether there was early evidence of atherosclerosis in an inducible hyperlipidemic mouse exposed to aerosol from commercial pod-style devices and e-liquid. Methods: Mice were injected with adeno-associated virus containing the human protein convertase subtilisin/kexin type 9 (PCSK9) variant to promote hyperlipidemia. These mice were fed a high-fat diet and exposed to room air or aerosol derived from JUUL pods containing polyethylene glycol/vegetable glycerin (PG/VG) or 5% nicotine with mango flavoring for 4 weeks; this timepoint was utilized to assess markers of atherosclerosis that may occur prior to the development of atherosclerotic plaques. Results: These data show that various parameters including weight, circulating lipoprotein/glucose levels, and splenic immune cells were significantly affected by exposure to PG/VG and/or nicotine-containing aerosols. Discussion: Not only can this mouse model be utilized for chronic vaping studies to assess the vascular pathology but these data support that vaping is not risk-free and may increase CVD outcomes later in life.

Blackberry consumption protects against e-cigarette-induced vascular oxidative stress in mice

Electronic cigarettes (e-cigarettes) have gained popularity; however, evidence for their safety with chronic use is lacking. Acute e-cigarette exposure induces systemic oxidative stress in users and contributes to vascular endothelial dysfunction through reduction in nitric oxide (NO). Polyphenols, abundant in blackberries (BL), mitigate cardiovascular damage. We aimed to determine whether BL was protective against e-cigarette-induced cardiopulmonary detriments. Mice were fed a diet supplemented with or without 5% freeze-dried BL (w/w) for 16 weeks. E-cigarette exposure (1 h, 5 days per week) began at week 4. Additionally, human microvascular endothelial cells (HMVECs) were treated with BL polyphenol extract (200 μg mL-1) and e-cigarette condensate (0.5% v/v). Twelve weeks of e-cigarette exposure induced multi-organ oxidative stress. E-cigarette exposure increased expression of pro-oxidant enzymes in the endothelium resulting in increased superoxide production diminishing NO bioavailability. Additionally, e-cigarettes reduced the phosphorylation of endothelial NO synthase, contributing to decreases in NO. Mice supplemented with BL were protected against decreases in NO and BL pre-treatment in vitro reduced superoxide production. However, BL was not able to attenuate oxidative stress responses in the heart or lungs. These studies demonstrate the contribution of e-cigarettes to vascular pathologies through an increase in superoxide-producing enzymes and the ability of BL polyphenols to mitigate these deleterious effects in the vasculature. Further studies should explore the role of polyphenol-rich foods in protecting against cardiopulmonary conditions induced by chronic e-cigarette use and explore their use in the recovery period post-e-cigarette cessation to properly align with current public health messaging.

E-cigarettes and arrhythmogenesis: a comprehensive review of pre-clinical studies and their clinical implications

Electronic cigarette use has grown exponentially in recent years, and while their popularity has increased, the long-term effects on the heart are yet to be fully studied and understood. Originally designed as devices to assist with those trying to quit traditional combustible cigarette use, their popularity has attracted use by teens and adolescents who traditionally have not smoked combustible cigarettes. Acute effects on the heart have been shown to be similar to traditional combustible cigarettes, including increased heart rate and blood pressure. The main components of electronic cigarettes that contribute to these arrhythmic effects are found in the e-liquid that is aerosolized and inhaled, comprised of nicotine, flavourings, and a combination of vegetable glycerin (VG) and propylene glycol (PG). Nicotine can potentially induce both ventricular and atrial arrhythmogenesis, with both the atrial and ventricular effects resulting from the interactions of nicotine and the catecholamines they release via potassium channels. Atrial arrhythmogenesis, more specifically atrial fibrillation, can also occur due to structural alterations, which happens because of nicotine downregulating microRNAs 133 and 590, both post-transcriptional growth factor repressors. Liquid flavourings and the combination of PG and VG can possibly lead to arrhythmic events by exposing users to acrolein, an aldehyde that stimulates TRPA1 that in turn causes a change towards sympathetic activation and autonomic imbalance. The design of these electronic delivery devices is constantly changing; therefore, it has proven extremely difficult to study the long-term effects on the heart caused by electronic cigarettes but will be important to understand given their rising popularity. The arrhythmic effects of electronic cigarettes appear similar to traditional cigarettes as well; however, a comprehensive review has not been compiled and is the focus of this article.

Electronic nicotine delivery systems (ENDS): A convenient means of smoking?

Electronic nicotine delivery systems (ENDS), which are becoming increasingly popular in many parts of the world, have recently become more sophisticated in terms of their more active content and better controlled vaporisation. This review begins by describing how cigarette smoking led to the development of ENDS as a means of combatting nicotine addiction. ENDS are usually categorised as belonging to one of only three main generations, but a fourth has been added in order to differentiate the latest, most powerful, most advanced and innovative that have improved heating efficiency. Descriptions of the principal substances contained in ENDS are followed by considerations concerning the risk of toxicity due to the presence of albeit low concentrations of such a variety of compounds inhaled over a long time, and the increasingly widespread use of ENDS as a means of smoking illicit drugs. We also review the most widely used pharmacotherapeutic approaches to smoking cessation, and recent epidemiological data showing that ENDS can help some people to stop smoking. However, in order to ensure their appropriate regulation, there is a need for higher-quality evidence concerning the health effects and safety of ENDS, and their effectiveness in discouraging tobacco smoking.

Impact of in-utero electronic cigarette exposure on neonatal neuroinflammation, oxidative stress and mitochondrial function

Introduction: Despite the prevalence of the perception that electronic cigarettes (e-cig) are a safer alternative to tobacco smoke, growing concern about their potential toxic impact warrants adequate investigation focusing on special populations like maternal and pediatric groups. This study evaluated the consequences of maternal e-cig use on neonatal neuroinflammation, oxidative stress, and mitochondrial function in primary cultured neurons and postnatal day (PD) 7 and 90 brain. Methodology: Pregnant CD1 mice were exposed to e-cig vapor (2.4% nicotine) from gestational day 5 (E5) till PD7, and the primary neurons were isolated from pups at E16/17. Cellular total reactive oxygen species (ROS) and mitochondrial superoxide were measured in primary neurons using CM-H2DCFDA and Mitosox red, respectively. Mitochondrial function was assessed by Seahorse XF Cell Mitostress analysis. The level of pro-inflammatory cytokines was measured in primary neurons and PD7 and PD90 brains by RT-PCR and immunobead assay. Western blot analysis evaluated the expression of antioxidative markers (SOD-2, HO-1, NRF2, NQO1) and that of the proinflammatory modulator NF-κB. Results: Significantly higher level of total cellular ROS (p < 0.05) and mitochondrial superoxide (p < 0.01) was observed in prenatally e-cig-exposed primary neurons. We also observed significantly reduced antioxidative marker expression and increased proinflammatory modulator and cytokines expression in primary neurons and PD7 (p < 0.05) but not in PD90 postnatal brain. Conclusion: Our findings suggest that prenatal e-cig exposure induces postnatal neuroinflammation by promoting oxidative stress (OS), increasing cytokines' levels, and disrupting mitochondrial function. These damaging events can alter the fetal brain's immune functions, making such offspring more vulnerable to brain insults.

Aerobic Exercise versus Electronic Cigarette in Vascular Aging Process: First Histological Insight

Smoking is related to vascular aging. However, the hazardous effect of e-cigarette is often debatable, with limited studies available. In contrast, moderate-intensity aerobic exercise is well known to decrease aortic stiffness. We provide novel research to determine the effect of e-cigarette and aerobic moderate-intensity exercise on the aortic structure of Wistar rats. A total of 26 male Wistar rats (Rattus norvegicus) 8 weeks aged, 200-250 g b.w., were randomly divided into 4 groups, namely, K0 (normal rats), K1 (rats were given moderate-intensity aerobic exercise by animal treadmill 20 m/30 min), K2 (rats were given e-cigarette with 6 mg nicotine, 40% propylene glycol, and 60% vegetable glycerine 30 min for 5 days/week), and K3 (rats were given e-cigarette and moderate-intensity aerobic exercise). After exposure for 6 weeks, all animals were sacrificed to isolate the aorta for histopathological analysis with hematoxylin-eosin stain to evaluate the elastic fiber layer and intimal-medial thickness. The Verhoeff-Van Gieson staining was done for quantification elastic lamina fragmentation. Our study found that the e-cigarette group had the highest elastic lamina fragmentation among groups (8.14 ± 2.85). The exercise only group showed the lowest elastic lamina fragmentation (2.50 ± 1.87). Fragmentation in the e-cigarette and exercise group was higher than in the exercise only group (5.83 ± 0.753 vs. 2.50 ± 1.87, p = 0.002). There is a significant difference of NO serum between four groups. The result of post hoc analysis using LSD showed that there is a significant difference of NO serum between K0 and K2, K0 and K3, K1 and K2, and K1 and K3. Therefore, our research demonstrated that the most injury of aorta elastic lamina was in the group that was exposed to e-cigarette that leads to vascular aging while exercise is not yet proven to reverse this effect.

The cardiovascular consequences of electronic cigarette smoking: a narrative review

INTRODUCTION

E-cigarettes have emerged as a popular alternative to traditional tobacco smoking in recent years. Despite their growing popularity, concerns have arisen regarding the cardiovascular implications of e-cigarette use.

AREAS COVERED

This narrative review aims to highlight the latest evidence on the impact of e-cigarettes on cardiovascular health.

EXPERT OPINION

Numerous studies have demonstrated that e-cigarette use can lead to acute adverse cardiovascular effects. Inhalation of e-cigarette aerosols exposes users to a wide range of potentially harmful substances that have been implicated in critical pathophysiologic pathways of cardiovascular disease, namely endothelial dysfunction, oxidative stress, inflammation, sympathetic overdrive, and arterial stiffness. While long-term epidemiological studies specifically focusing on the cardiovascular effects of e-cigarettes are still relatively scarce, early evidence suggests a potential association between e-cigarette use and an increased risk of adverse cardiovascular events. However, it is essential to recognize that e-cigarettes are relatively new products, and the full extent of their long-term cardiovascular impact has not been fully elucidated. In the meantime, promoting tobacco cessation strategies that are evidence-based and regulated, along with rigorous monitoring of e-cigarette use patterns and associated health outcomes, are essential steps in safeguarding cardiovascular health in the face of this emerging public health challenge.

Nicotine promotes e-cigarette vapour-induced lung inflammation and structural alterations

BACKGROUND

Electronic cigarette (e-cigarette) vapour is gaining popularity as an alternative to tobacco smoking and can induce acute lung injury. However, the specific role of nicotine in e-cigarette vapour and its long-term effects on the airways, lung parenchyma and vasculature remain unclear.

RESULTS

In vitro exposure to nicotine-containing e-cigarette vapour extract (ECVE) or to nicotine-free e-cigarette vapour extract (NF ECVE) induced changes in gene expression of epithelial cells and pulmonary arterial smooth muscle cells (PASMCs), but ECVE in particular caused functional alterations (e.g. a decrease in human and mouse PASMC proliferation by 29.3±5.3% and 44.3±8.4%, respectively). Additionally, acute inhalation of nicotine-containing e-cigarette vapour (ECV) but not nicotine-free e-cigarette vapour (NF ECV) increased pulmonary endothelial permeability in isolated lungs. Long-term in vivo exposure of mice to ECV for 8 months significantly increased the number of inflammatory cells, in particular lymphocytes, compared to control and NF ECV in the bronchoalveolar fluid (BALF) (ECV: 853.4±150.8 cells·mL-1; control: 37.0±21.1 cells·mL-1; NF ECV: 198.6±94.9 cells·mL-1) and in lung tissue (ECV: 25.7±3.3 cells·mm-3; control: 4.8±1.1 cells·mm-3; NF ECV: 14.1±2.2 cells·mm-3). BALF cytokines were predominantly increased by ECV. Moreover, ECV caused significant changes in lung structure and function (e.g. increase in airspace by 17.5±1.4% compared to control), similar to mild tobacco smoke-induced alterations, which also could be detected in the NF ECV group, albeit to a lesser degree. In contrast, the pulmonary vasculature was not significantly affected by ECV or NF ECV.

CONCLUSIONS

NF ECV components induce cell type-specific effects and mild pulmonary alterations, while inclusion of nicotine induces significant endothelial damage, inflammation and parenchymal alterations.

Integrating a Systematic, Comprehensive E-Cigarette and Vaping Assessment Tool into the Electronic Health Record

BACKGROUND

Recently, the use of electronic cigarettes increased sharply, leading to increased e-cigarette, or Vaping Product Use-Associated Lung Injury (EVALI), and other acute pulmonary conditions. There is an urgent need for clinical information about e-cigarette users to identify factors that contribute to EVALI. We developed an e-cigarette/vaping assessment tool (EVAT) that was integrated into the Electronic Health Record (EHR) of a large state-wide medical system and initiated a system-wide dissemination and education to support its use.

METHODS

EVAT documented current vaping status, history, and e-cigarette content (nicotine, cannabinoids, and/or flavoring). Educational materials and presentations were developed via a comprehensive literature review. EVAT utilization in the EHR was assessed quarterly. Patients' demographic data and clinical site name were also collected.

RESULTS

The EVAT was built, validated, and integrated with the EHR in July 2020. Live and virtual seminars were conducted for prescribing providers and clinical staff. Asynchronous training was offered using podcasts, e-mails, and Epic tip sheets. Participants were informed about vaping harm and EVALI and instructed on the use of EVAT. As of December 31, 2022, EVAT was used 988,181 times, with 376,559 unique patients evaluated. Overall, 1,063 hospital units and affiliated ambulatory clinics used EVAT, including 64 Primary Care, 95 Pediatrics, and 874 Specialty sites.

CONCLUSIONS

EVAT was successfully implemented. Continued outreach efforts are needed to further increase its usage. Education materials should be enhanced to help providers to reach youth and vulnerable populations and connect patients to the tobacco treatment resources.

Genotoxicity and hypomethylation of LINE-1 induced by electronic cigarettes

Currently, the marketing of electronic cigarettes as a safe alternative to smoking has increased, which is associated with greater use of these devices, especially among young people and smokers interested in quitting tobacco cigarettes. Given the growing use of this type of product, there is a need to determine the consequences of electronic cigarettes on human health, especially since many of the compounds contained in the aerosol and liquid of these devices have a high potential to be carcinogenic and genotoxic. Additionally, many of these compounds' aerosol concentrations exceed the safe limits. We have evaluated the levels of genotoxicity and changes in DNA methylation patterns associated with vaping. We analyzed a total of 90 peripheral blood samples from a population of vapers (n = 32), smokers (n = 18), and controls (n = 32), in which the frequencies of genotoxicity were determined by the cytokinesis-blocking micronuclei (CBMN) assay and the patterns of methylation of the repetitive elements of LINE-1 through the Quantitative Methylation Specific PCR (qMSP) assay. Here we show an increase in genotoxicity levels associated with vaping habits. Additionally, the group of vapers showed changes at the epigenetic level specifically associated with the loss of methylation of the LINE-1 elements. These changes in LINE-1 methylation patterns were reflected in its representative RNA expression detected in vapers.

Electronic Nicotine Delivery Systems and Cardiovascular/Cardiometabolic Health

The use of electronic nicotine delivery systems, specifically electronic cigarettes (e-cig), has risen dramatically within the last few years; the demographic purchasing these devices is now predominantly adolescents that are not trying to quit the use of traditional combustible cigarettes, but rather are new users. The composition and appearance of these devices has changed since their first entry into the market in the late 2000s, but they remain composed of a battery and aerosol delivery system that is used to deliver breakdown products of propylene glycol/vegetable glycerin, flavorings, and potentially nicotine or other additives. Manufacturers have also adjusted the type of nicotine that is used within the liquid to make the inhalation more palatable for younger users, further affecting the number of youth who use these devices. Although the full spectrum of cardiovascular and cardiometabolic consequences of e-cig use is not fully appreciated, data is beginning to show that e-cigs can cause both short- and long-term issues on cardiac function, vascular integrity and cardiometabolic issues. This review will provide an overview of the cardiovascular, cardiometabolic, and vascular implications of the use of e-cigs, and the potential short- and long-term health effects. A robust understanding of these effects is important in order to inform policy makers on the dangers of e-cigs use.

Maternal e-cigarette use can disrupt postnatal blood-brain barrier (BBB) integrity and deteriorates motor, learning and memory function: influence of sex and age

Electronic nicotine delivery systems (ENDS), also commonly known as electronic cigarettes (e-cigs) are considered in most cases as a safer alternative to tobacco smoking and therefore have become extremely popular among all age groups and sex. It is estimated that up to 15% of pregnant women are now using e-cigs in the US which keeps increasing at an alarming rate. Harmful effects of tobacco smoking during pregnancy are well documented for both pregnancy and postnatal health, however limited preclinical and clinical studies exist to evaluate the long-term effects of prenatal e-cig exposure on postnatal health. Therefore, the aim of our study is to evaluate the effect of maternal e-cig use on postnatal blood-brain barrier (BBB) integrity and behavioral outcomes of mice of varying age and sex. In this study, pregnant CD1 mice (E5) were exposed to e-Cig vapor (2.4% nicotine) until postnatal day (PD) 7. Weight of the offspring was measured at PD0, PD7, PD15, PD30, PD45, PD60 and PD90. The expression of structural elements of the BBB, tight junction proteins (ZO-1, claudin-5, occludin), astrocytes (GFAP), pericytes (PDGFRβ) and the basement membrane (laminin α1, laminin α4), neuron specific marker (NeuN), water channel protein (AQP4) and glucose transporter (GLUT1) were analyzed in both male and female offspring using western blot and immunofluorescence. Estrous cycle was recorded by vaginal cytology method. Long-term motor and cognitive functions were evaluated using open field test (OFT), novel object recognition test (NORT) and morris water maze test (MWMT) at adolescence (PD 40-45) and adult (PD 90-95) age. In our study, significantly reduced expression of tight junction proteins and astrocyte marker were observed in male and female offspring until PD 90 (P < 0.05). Additionally, prenatally e-cig exposed adolescent and adult offspring showed impaired locomotor, learning, and memory function compared to control offspring (P < 0.05). Our findings suggest that prenatal e-cig exposure induces long-term neurovascular changes of neonates by disrupting postnatal BBB integrity and worsening behavioral outcomes.

Short-term exposure to JUUL electronic cigarettes can worsen ischemic stroke outcome

BACKGROUND

The short and long-term health effects of JUUL electronic cigarette (e-Cig) are largely unknown and warrant extensive research. We hypothesized that JUUL exposure could cause cerebrovascular toxicities impacting the progression and outcome of ischemic stroke comparable to tobacco smoke (TS) exposure.

METHODS

We exposed male C57 mice to TS/JUUL vapor for 14 days. LCMS/MS was used to measure brain and plasma nicotine and cotinine level. Transient middle cerebral artery occlusion (tMCAO) followed by reperfusion was used to mimic ischemic stroke. Plasma levels of IL-6 and thrombomodulin were assessed by enzyme-linked immunosorbent assay. At the same time, western blotting was used to study blood-brain barrier (BBB) tight junction (TJ) proteins expression and key inflammatory and oxidative stress markers.

RESULTS

tMCAO upregulated IL-6 and decreased plasma thrombomodulin levels. Post-ischemic brain injury following tMCAO was significantly worsened by JUUL/TS pre-exposure. TJ proteins expression was also downregulated by JUUL/TS pre-exposure after tMCAO. Like TS, exposure to JUUL downregulated the expression of the antioxidant Nrf2. ICAM-1 was upregulated in mice subjected to tMCAO following pre-exposure to TS or JUUL, with a greater effect of TS than JUUL.

CONCLUSIONS

These results suggest that JUUL exposure could negatively impact the cerebrovascular system, although to a lesser extent than TS exposure.

An integral perspective of canonical cigarette and e-cigarette-related cardiovascular toxicity based on the adverse outcome pathway framework

BACKGROUND

Nowadays, cigarette smoking remains the leading cause of chronic disease and premature death, especially cardiovascular disease. As an emerging tobacco product, e-cigarettes have been advocated as alternatives to canonical cigarettes, and thus may be an aid to promote smoking cessation. However, recent studies indicated that e-cigarettes should not be completely harmless to the cardiovascular system.

AIM OF REVIEW

This review aimed to build up an integral perspective of cigarettes and e-cigarettes-related cardiovascular toxicity.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review adopted the adverse outcome pathway (AOP) framework as a pivotal tool and aimed to elucidate the association between the molecular initiating events (MIEs) induced by cigarette and e-cigarette exposure to the cardiovascular adverse outcome. Since the excessive generation of reactive oxygen species (ROS) has been widely approved to play a critical role in cigarette smoke-related CVD and may also be involved in e-cigarette-induced toxic effects, the ROS overproduction and subsequent oxidative stress are regarded as essential parts of this framework. As far as we know, this should be the first AOP framework focusing on cigarette and e-cigarette-related cardiovascular toxicity, and we hope our work to be a guide in exploring the biomarkers and novel therapies for cardiovascular injury.

Nicotine and cotinine quantification after a 4-week inhalation of electronic cigarette vapors in male and female mice using UPLC-MS/MS

OBJECTIVES

To detect the cotinine and nicotine serum concentrations of female and male C57BL/6J mice after a 4-week exposure to electronic (e)-cigarette vapors using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

METHODS

This experimental study was carried out at an animal facility and laboratories, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia, between January and August 2020. A 4-week exposure to e-cigarettes was carried out using male and female mice and serum samples were obtained for cotinine and nicotine quantification using UPLC-MS/MS. The chromatographic procedures involved the use of a BEH HSS T3 C18 column (100 mm x 2.1 mm, 1.7 μm) with acetonitrile as a mobile phase and 0.1% formic acid (2:98 v/v).

RESULTS

The applied methodology has highly efficient properties of detection, estimation, and extraction, where the limit of quantification (LOQ) for nicotine was 0.57 ng/mL and limit of detection (LOD) for nicotine was 0.19 ng/mL, while the LOQ for cotinine was 1.11 ng/mL and LOD for cotinine was 0.38 ng/mL. The correlation coefficient was r²>0.99 for both compounds. The average recovery rate was 101.6±1.33 for nicotine and 100.4±0.54 for cotinine, while the precision and accuracy for cotinine and nicotine were less than 6.1. The serum cotinine level was higher in males (433.7±19.55) than females (362.3±16.27).

CONCLUSION

This study showed that the gender factor might play a crucial role in nicotine metabolism.

Health effects and known pathology associated with the use of E-cigarettes

In recent years, new nicotine delivery methods have emerged, and many users are choosing electronic cigarettes (e-cigarettes) over traditional tobacco cigarettes. E-cigarette use is very popular among adolescents, with more than 3.5 million currently using these products in the US. Despite the increased prevalence of e-cigarette use, there is limited knowledge regarding the health impact of e-cigarettes on the general population. Based on published findings by others, E-cigarette is associated with lung injury outbreak, which increased health and safety concerns related to consuming this product. Different components of e-cigarettes, including food-safe liquid solvents and flavorings, can cause health issues related to pneumonia, pulmonary injury, and bronchiolitis. In addition, e-cigarettes contain alarmingly high levels of carcinogens and toxicants that may have long-lasting effects on other organ systems, including the development of neurological manifestations, lung cancer, cardiovascular disorders, and tooth decay. Despite the well- documented potential for harm, e-cigarettes do not appear to increase susceptibility to SARS-CoV- 2 infection. Furthermore, some studies have found that e-cigarette users experience improvements in lung health and minimal adverse effects. Therefore, more studies are needed to provide a definitive conclusion on the long-term safety of e-cigarettes. The purpose of this review is to inform the readers about the possible health-risks associated with the use of e-cigarettes, especially among the group of young and young-adults, from a molecular biology point of view.

E-cigarette exposure with or without heating the e-liquid induces differential remodeling in the lungs and right heart of mice

Various cardiopulmonary pathologies associated with electronic cigarette (EC) vaping have been reported. This study investigated the differential adverse effects of heating-associated by-products versus the intact components of EC aerosol to the lungs and heart of mice. We further dissected the roles of caspase recruitment domain-containing protein 9 (CARD9)-associated innate immune response and NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome in EC exposure-induced cardiopulmonary injury. C57BL/6 wild type (WT), CARD9^-/-, and NLRP3^-/- mice were exposed to EC aerosol 3 h/day, 5 days/week for 6 month with or without heating the e-liquid with exposure to ambient air as the control. In WT mice, EC exposure with heating (EwH) significantly increased right ventricle (RV) free wall thickness at systole and diastole. However, EC exposure without heating (EwoH) caused a significant decrease in the wall thickness at systole. RV fractional shortening was also markedly reduced following EwH in WT and NLRP3^-/- mice. Further, EwH activated NF-κB and p38 MAPK inflammatory signaling in the lungs, but not in the RV, in a CARD9- and NLRP3-dependent manner. Levels of circulatory inflammatory mediators were also elevated following EwH, indicating systemic inflammation. Moreover, EwoH activated TGF-β1/SMAD2/3/α-SMA fibrosis signaling in the lungs but not the RV of WT mice. In conclusion, EC aerosol exposure following EwH or EwoH induced differential cardiopulmonary remodeling and CARD9 innate immune and NLRP3 inflammasome contributed to the adverse effects.

Fundamentals of vaping-associated pulmonary injury leading to severe respiratory distress

Vaping of flavored liquids has been touted as safe alternative to traditional cigarette smoking with decreased health risks. The popularity of vaping has dramatically increased over the last decade, particularly among teenagers who incorporate vaping into their daily life as a social activity. Despite widespread and increasing adoption of vaping among young adults, there is little information on long-term consequences of vaping and potential health risks. This study demonstrates vaping-induced pulmonary injury using commercial JUUL pens with flavored vape juice using an inhalation exposure murine model. Profound pathological changes to upper airway, lung tissue architecture, and cellular structure are evident within 9 wk of exposure. Marked histologic changes include increased parenchyma tissue density, cellular infiltrates proximal to airway passages, alveolar rarefaction, increased collagen deposition, and bronchial thickening with elastin fiber disruption. Transcriptional reprogramming includes significant changes to gene families coding for xenobiotic response, glycerolipid metabolic processes, and oxidative stress. Cardiac systemic output is moderately but significantly impaired with pulmonary side ventricular chamber enlargement. This vaping-induced pulmonary injury model demonstrates mechanistic underpinnings of vaping-related pathologic injury.

E-Cigarette Use: Device Market, Study Design, and Emerging Evidence of Biological Consequences

Electronic cigarettes are frequently viewed as a safer alternative to conventional cigarettes; however, evidence to support this perspective has not materialized. Indeed, the current literature reports that electronic cigarette use is associated with both acute lung injury and subclinical dysfunction to the lung and vasculature that may result in pathology following chronic use. E-cigarettes can alter vascular dynamics, polarize innate immune populations towards a proinflammatory state, compromise barrier function in the pulmonary endothelium and epithelium, and promote pre-oncogenic phenomena. This review will summarize the variety of e-cigarette products available to users, discuss current challenges in e-cigarette study design, outline the range of pathologies occurring in cases of e-cigarette associated acute lung injury, highlight disease supporting tissue- and cellular-level changes resulting from e-cigarette exposure, and briefly examine how these changes may promote tumorigenesis. Continued research of the mechanisms by which e-cigarettes induce pathology benefit users and clinicians by resulting in increased regulation of vaping devices, informing treatments for emerging diseases e-cigarettes produce, and increasing public awareness to reduce e-cigarette use and the onset of preventable disease.

VAPIng into ARDS: Acute Respiratory Distress Syndrome and Cardiopulmonary Failure

"Modern" vaping involving battery-operated electronic devices began approximately one dozen years and has quickly evolved into a multibillion dollar industry providing products to an estimated 50 million users worldwide. Originally developed as an alternative to traditional cigarette smoking, vaping now appeals to a diverse demographic including substantial involvement of young people who often have never used cigarettes. The rapid rise of vaping fueled by multiple factors has understandably outpaced understanding of biological effects, made even more challenging due to wide ranging individual user habits and preferences. Consequently while vaping-related research gathers momentum, vaping-associated pathological injury (VAPI) has been established by clinical case reports with severe cases manifesting as acute respiratory distress syndrome (ARDS) with examples of right ventricular cardiac failure. Therefore, basic scientific studies are desperately needed to understand the impact of vaping upon the lungs as well as cardiopulmonary structure and function. Experimental models that capture fundamental characteristics of vaping-induced ARDS are essential to study pathogenesis and formulate recommendations to mitigate harmful effects attributable to ingredients or equipment. So too, treatment strategies to promote recovery from vaping-associated damage require development and testing at the preclinical level. This review summarizes the back story of vaping leading to present day conundrums with particular emphasis upon VAPI-associated ARDS and prioritization of research goals.

Extracorporeal Life Support for Respiratory Failure in Patients With Electronic Cigarette or Vaping Product Use-Associated Lung Injury

OBJECTIVES

Electronic cigarette or vaping product use-associated lung injury is a clinical entity that can lead to respiratory failure and death. Despite the severity of electronic cigarette or vaping product use-associated lung injury, the role of extracorporeal life support in its management remains unclear. Our objective was to describe the clinical characteristics and outcomes of patients with electronic cigarette or vaping product use-associated lung injury who received extracorporeal life support.

DESIGN

We performed a retrospective review of records of electronic cigarette or vaping product use-associated lung injury patients who received extracorporeal life support. Standardized data were collected via direct contact with extracorporeal life support centers. Data regarding presentation, ventilatory management, extracorporeal life support details, and outcome were analyzed.

SETTING

This was a multi-institutional, international case series with patients from 10 different institutions in three different countries.

PATIENTS

Patients who met criteria for confirmed electronic cigarette or vaping product use-associated lung injury (based on previously reported diagnostic criteria) and were placed on extracorporeal life support were included. Patients were identified via literature review and by direct contact with extracorporeal life support centers.

MEASUREMENTS AND MAIN RESULTS

Data were collected for 14 patients ranging from 16 to 45 years old. All had confirmed vape use within 3 months of presentation. Nicotine was the most commonly used vaping product. All patients had respiratory symptoms and radiographic evidence of bilateral pulmonary opacities. IV antibiotics and corticosteroids were universally initiated. Patients were intubated for 1.9 days (range, 0-6) prior to extracorporeal life support initiation. Poor oxygenation and ventilation were the most common indications for extracorporeal life support. Five patients showed evidence of ventricular dysfunction on echocardiography. Thirteen patients (93%) were placed on venovenous extracorporeal life support, and one patient required multiple rounds of extracorporeal life support. Total extracorporeal life support duration ranged from 2 to 37 days. Thirteen patients survived to hospital discharge; one patient died of septic shock.

CONCLUSIONS

Electronic cigarette or vaping product use-associated lung injury can cause refractory respiratory failure and hypoxemia. These data suggest that venovenous extracorporeal life support can be an effective treatment option for profound, refractory respiratory failure secondary to electronic cigarette or vaping product use-associated lung injury.

The chemistry and toxicology of vaping

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

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

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

Nicotine-free vapor inhalation produces behavioral disruptions and anxiety-like behaviors in mice: Effects of puff duration, session length, sex, and flavor

Electronic-cigarette's (ECIGs) popularity has grown over the last decade and changed the way individuals administer nicotine. Preclinical research is imperative for understanding the addictive properties and health-risks associated with ECIG use; however, there is not a standard dosing regimen used across research laboratories. The main objective was to determine how vapor puff durations, administration session length, and flavored e-liquid alter general and mood-disorder related behaviors while providing a foundation of vapor administration parameters. Adult male and female C57BL/6 mice were exposed to several nicotine-free unflavored vapor puff durations (1, 3, 6, or 10 s) and vapor administration session lengths (10 and 30 min) then measured on the following assays: locomotor activity (LMA), tail suspension test (TST), and light-dark test. The effects of mecamylamine and the time-course of vapor-induced depression of LMA also were assessed. Additionally, mice were exposed to flavored (strawberry and adventurers tobacco blend) vapor inhalation and measured on locomotor activity, tail suspension test, and light-dark test. Following both 10 and 30 min vapor administration session, there was a puff duration-dependent decrease in distance traveled, time in center, and rearing. The vapor-induced depression of LMA was not mediated by nicotine or nicotinic acetylcholine receptor (nAChR) activation and lasted 60-90 min. The 10 s puff duration produced an anxiogenic-like effect in the light-dark test by decreasing the time spent in the light side. Vapor inhalation did not significantly alter TST behavior. No significant effects of sex or flavor were found. The anxiogenic-like effects of nicotine-free vapor inhalation are concerning as many adolescents vape nicotine-free flavored e-liquid, and there is an association between ECIGs and mood disorders. Additionally, these studies demonstrate that vapor puff duration, but not vapor administration session length, is an important variable to consider during research design as it can become a confounding variable and alter baseline behaviors.

Long-term electronic cigarette exposure induces cardiovascular dysfunction similar to tobacco cigarettes: role of nicotine and exposure duration

Electronic cigarette (e-cig) vaping (ECV) has been proposed as a safer alternative to tobacco cigarette smoking (TCS); however, this remains controversial due to a lack of long-term comparative studies. Therefore, we developed a chronic mouse exposure model that mimics human vaping and allows comparison with TCS. Longitudinal studies were performed to evaluate alterations in cardiovascular function with TCS and ECV exposure durations of up to 60 wk. For ECV, e-cig liquid with box-mod were used and for TCS, 3R4F-cigarettes. C57/BL6 male mice were exposed 2 h/day, 5 days/wk to TCS, ECV, or air control. The role of vape nicotine levels was evaluated using e-cig-liquids with 0, 6, or 24 mg/mL nicotine. Following 16-wk exposure, increased constriction to phenylephrine and impaired endothelium-dependent and endothelium-independent vasodilation were observed in aortic segents, paralleling the onset of systemic hypertension, with elevations in systemic vascular resistance. Following 32 wk, TCS and ECV induced cardiac hypertrophy. All of these abnormalities further increased out to 60 wk of exposure, with elevated heart weight and aortic thickness along with increased superoxide production in vessels and cardiac tissues of both ECV and TCS mice. While ECV-induced abnormalities were seen in the absence of nicotine, these occurred earlier and were more severe with higher nicotine exposure. Thus, long-term vaping of e-cig can induce cardiovascular disease similar to TCS, and the severity of this toxicity increases with exposure duration and vape nicotine content.NEW & NOTEWORTHY A chronic mouse exposure model that mimics human e-cigarette vaping and allows comparison with tobacco cigarette smoking was developed and utilized to perform longitudinal studies of alterations in cardiovascular function. E-cigarette exposure led to the onset of cardiovascular disease similar to that with tobacco cigarette smoking. Impaired endothelium-dependent and endothelium-independent vasodilation with increased adrenergic vasoconstriction were observed, paralleling the onset of systemic hypertension and subsequent cardiac hypertrophy. This cardiovascular toxicity was dependent on exposure duration and nicotine dose.

Whole body electronic cigarette exposure system for efficient evaluation of diverse inhalation conditions and products

Objectives: To develop and test a new system for whole body exposure of small animals to support investigation of the biological effects of aerosol generated by electronic cigarette (e-cig) products under diverse inhalation conditions with improved control and monitoring of the e-cig vape exposure and nicotine delivered to the animal's systemic circulation. Methods: A computer-controlled design, with built-in sensors for real time monitoring of O₂, CO₂, relative humidity, and temperature within the exposure chambers and port for measuring total particulate matter (TPM) was developed, constructed and tested. This design accommodates a variety of commercial vaping devices, offers software flexibility to adjust exposure protocols to mimic different users' puffing patterns, enables variable nicotine delivery to the animal's systemic circulation; minimizes travel time and alterations of aerosol quality or quantity by delivering aerosol directly to the exposure chamber, offers local or remote operation of up to six distinct exposure chambers from a single control unit, and can simultaneously test different exposure conditions or products in diverse animal groups, which reduces inter-run variability, saves time, and increases productivity. Results: The time course pattern of TPM concentration during different phases of the exposure cycle was measured. With increased puffing duration or number of exposure cycles, higher TPM exposure and plasma cotinine levels were observed with plasma cotinine levels in the range reported in light or heavy smokers. Conclusion: Overall, this novel, versatile, and durable exposure system facilitates high-throughput evaluation of the relative safety and potential toxicity of a variety of e-cig devices and liquids.

Effects of e-cigarettes and vaping devices on cardiac and pulmonary physiology

E-cigarette aerosols are exceedingly different from conventional tobacco smoke, containing dozens of chemicals not found in cigarette smoke. It is highly likely that chronic use of e-cigarettes will induce pathological changes in both the heart and lungs. Here we review human and animal studies published to date and summarize the cardiopulmonary physiological changes caused by vaping. In terms of cardiac physiology, acute exposure to e-cigarette aerosols in human subjects led to increased blood pressure and heart rate, similar to traditional cigarettes. Chronic exposure to e-cigarette aerosols using animal models caused increased arterial stiffness, vascular endothelial changes, increased angiogenesis, cardiorenal fibrosis and increased atherosclerotic plaque formation. Pulmonary physiology is also affected by e-cigarette aerosol inhalation, with increased airway reactivity, airway obstruction, inflammation and emphysema. Research thus far demonstrates that the heart and lung undergo numerous changes in response to e-cigarette use, and disease development will depend on how those changes combine with both environmental and genetic factors. E-cigarettes have been advertised as a healthy alternative to cigarette smoking, and users are under the impression that vaping of e-cigarettes is harmless, but these claims that e-cigarettes are safer and healthier are not based on evidence. Data from both humans and animal models are consistent in demonstrating that vaping of e-cigarettes causes health effects both similar to and disparate from those of cigarette smoking. Further work is needed to define the long-term cardiopulmonary effects of e-cigarette use in humans.

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

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

Electronic cigarettes cause alteration in cardiac structure and function in diet-induced obese mice

In spite of the widespread use of electronic cigarettes, also known as e-cigarettes, and the proposed adverse cardiac effects of nicotine, the detrimental effects of e-cigarettes on the heart are not well known. This study examines the detrimental effects of e-cigarettes with nicotine at doses that yield circulating nicotine and cotinine in the ranges similar to the levels found in habitual smokers, and a high fat diet (HFD) on cardiac structure and function in a commonly used model of diet-induced obesity (DIO). C57BL/6J mice on an HFD were exposed to e-cigarette in the presence (2.4% nicotine) or absence (0% nicotine) of nicotine and saline aerosol for 12 weeks. Echocardiographic data demonstrated a decrease in left ventricular (LV) fractional shortening, LV ejection fraction, and velocity of circumferential fiber shortening (VCF) in mice treated with e-cigarette (2.4% nicotine) compared to e-cigarette (0% nicotine) or saline exposed mice. Cardiomyocytes (CMs) of mice treated with e-cigarette (2.4% nicotine) exhibited LV abnormalities, including lipid accumulation (ventricular steatosis), myofibrillar derangement and destruction, and mitochondrial hypertrophy, as revealed by transmission electron microscopy. The detrimental effects of e-cigarettes (2.4% nicotine) on cardiac structure and function was accompanied by increased oxidative stress, plasma free fatty acid levels, CM apoptosis, and inactivation of AMP-activated protein kinase and activation of its downstream target, acetyl-CoA-carboxylase. Our results indicate profound adverse effects of e-cigarettes (2.4% nicotine) on the heart in obese mice and raise questions about the safety of the nicotine e-cigarettes use.

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.

In vivo assessment of the toxicity of electronic cigarettes to zebrafish (Danio rerio) embryos, following gestational exposure, in terms of mortality, developmental toxicity, and hair cell damage: Toxicity of E-cigs to zebrafish embryos

With the ban of conventional cigarettes from public spaces, electronic cigarette (E-cig) liquids have emerged as a nicotine replacement treatment for smoking cessation. However, consumers possess little knowledge of the ingredients and health effects of E-cig liquids following exposure. This study evaluated hair cell damage and developmental toxicities following gestational exposure to E-cig liquids. Zebrafish embryos were exposed to E-cig liquids at different concentrations (0.1%, 0.2%, and 0.4%). Embryonic developmental toxicity and hair cell damage was evaluated at 6 and 7 d, respectively, after fertilization. The average number of hair cells in the anterior lateral line (ALL) and posterior lateral line (PLL) following E-cig exposure was compared to that of the control. Morphological abnormalities and heart rate were evaluated. E-cig liquids significantly damaged the hair cells in the ALL, compared to the control (control; 52.85 ± 5.29 cells, 0.1% E-cig; 49.43 ± 7.70 cells, 0.2% E-cig; 40.68 ± 12.00 cells, 0.4% E-cig; 32.14 ± 20.75%; n = 29-40; p < 0.01). At high concentrations, E-cig liquids significantly damaged the hair cells in the PLL (control; 36.88 ± 5.43 cells, 0.1% E-cig; 33.06 ± 5.21 cells, 0.2% E-cig; 30.95 ± 8.03 cells, 0.4% E-cig; 23.72 ± 15.53%, n = 29-40; p < 0.01). No morphological abnormalities in body shape, somites, notochord, tail, and pectoral fin were observed; however, abnormalities were observed in the dorsal fin and heart rate at high concentrations. Thus, gestational exposure to E-cigs significantly damaged hair cells in a concentration-dependent manner and induced developmental toxicities to the dorsal fin and heart rate at high concentrations.

Electronic cigarette exposure disrupts blood-brain barrier integrity and promotes neuroinflammation

Electronic cigarette (e-cigarette) use has grown substantially since inception, particularly among adolescents and combustible tobacco users. Several cigarette smoke constituents with known neurovascular effect are present in e-cigarette liquids or formed during the vapor generation. The present study establishes inhaled models of cigarette and e-cigarette use with normalized nicotine delivery, then characterizes the impact on blood-brain barrier (BBB) function. Sequencing of microvessel RNA following exposure revealed downregulation of several genes with critical roles in BBB function. Reduced protein expression of Occludin and Glut1 is also observed at the tight junction in all groups following exposure. Pro-inflammatory changes in leukocyte-endothelial cell interaction are also noted, and mice exposed to nicotine-free e-cigarettes have impaired novel object recognition performance. On this basis, it is concluded that long term e-cigarette use may adversely impact neurovascular health. The observed effects are noted to be partly independent of nicotine content and nicotine may even serve to moderate the effects of non-nicotinic components on the blood-brain barrier.

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.

How bad are e-cigarettes? What can we learn from animal exposure models?

Electronic cigarettes divide opinions. Some consider them key to reducing smoking incidence while others are concerned over potential for detrimental health consequences. It will take many years to identify the health consequences of e-cigarette use if we rely only upon human data. However, there is a growing body of work using rodent models that inform on these potential toxicities. These studies have focused upon the pulmonary, cardiovascular and central nervous systems. Observations include perturbations of pro-inflammatory, pro-fibrotic and oxidative stress markers, sometimes together with DNA damage and downregulation of DNA repair and antioxidant enzymes. However, the markers affected are often different between studies. A more consistent observation has been the increase in airway hyperresponsiveness, a characteristic of asthma, on exposure to electronic cigarettes, across mouse strains, sex and ages. Detrimental effects in this and other susceptible animal models such as the apolipoprotein E knock-out mouse model of atherosclerosis, suggest greater risk where there is an existing predisposition. Other adverse reactions, including weight loss, oxidative stress and angiogenesis, are reported in animal studies with nicotine-containing devices. These effects remain less severe than cigarette smoke, where investigated. Animal studies have identified therefore that e-cigarettes are potentially hazardous, especially in susceptible populations, nicotine is integral to risk of health effects, but overall e-cigarettes are much less hazardous than cigarettes.

Recent findings in the pharmacology of inhaled nicotine: Preclinical and clinical in vivo studies

INTRODUCTION

The rise of vaping in adolescents, the recent entrance of new inhaled nicotine products such as iQOS on the market and e-cigarette or vaping product use-associated lung injury cases has created concern for the use of inhaled non-combustible nicotine products. This narrative review discusses recent experimental in vivo studies that utilize human, rat and mouse models to understand the pharmacological impact of nicotine from non-combustible products.

METHODS

The search engine PubMed was utilized with the following search terms: inhaled nicotine, nicotine e-cigarette, heated tobacco products, iQOS, electronic cigarette, nicotine inhaler, nicotine vaping. This review highlights recent primary in vivo studies of inhaled nicotine administration experimental paradigms that occurred in laboratory settings using human and rodent (rats and mice) models that have been published from January 2017-December 2019.

RESULTS

The pharmacokinetics of nicotine via e-cigarettes is influenced by the PG/VG and flavor constituents in e-liquids, the presence of nicotine salts in e-liquids, puff topography of nicotine and tobacco product users and the power of the e-cigarette device. The pharmacodynamic impact of inhaled nicotine has cardiovascular, pulmonary and central nervous system implications.

CONCLUSION

The articles reviewed here highlight the importance of both animal and human models to fully understand the impact of inhaled nicotine pharmacology There is a need for more rodent pharmacokinetic inhaled nicotine studies to understand the influences of factors such as flavor and nicotine salts. Additionally, consensus on nicotine measurement in both human and rodent studies is greatly needed.

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?

Prenatal electronic cigarette exposure decreases brain glucose utilization and worsens outcome in offspring hypoxic-ischemic brain injury

It has been shown that prenatal nicotine and tobacco smoke exposure can cause different neurobehavioral disorders in the offspring. We hypothesize that prenatal exposure to nicotine-containing electronic cigarette (e-Cig) vapor can predispose newborn to enhanced sensitivity to hypoxic-ischemic (HI) brain injury and impaired motor and cognitive functions. In this study, pregnant CD1 mice were exposed to e-Cig vapor (2.4% nicotine). Primary cortical neurons isolated from e-Cig exposed fetus were exposed to oxygen-glucose deprivation followed by reoxygenation (OGD/R) to mimic HI brain injury. Cell viability and glucose utilization were analyzed in these neurons. HI brain injury was induced in 8-9-day-old pups. Short-term brain injury was evaluated by triphenyltetrazolium chloride staining. Long-term motor and cognitive functions were evaluated by open field, novel object recognition, Morris water maze, and foot fault tests. Western blotting and immunofluorescence were done to characterize glucose transporters in offspring brain. We found that e-Cig exposed neurons demonstrated decreased cell viability and glucose utilization in OGD/R. Prenatally e-Cig exposed pups also had increased brain injury and edema 24 hr after HI brain injury. Further, in utero e-Cig exposed offspring with HI brain injury displayed impaired memory, learning, and motor coordination at adolescence. Additionally, the expression of glucose transporters decreased in e-Cig exposed offspring brain after HI brain injury. These results indicate that reduced glucose utilization can contribute to prenatal e-Cig exposure induced worsened HI brain injury in offspring. This study is instrumental in elucidating the possible deleterious effects of e-Cig use in the general population.

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

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

A custom-built low-cost chamber for exposing rodents to e-cigarette aerosol: practical considerations

Objectives: To (1) design and build a low-cost exposure chamber system for whole-body exposure of rodents to electronic cigarette aerosol, (2) provide detailed instructions with particular focus on automated e-cigarette activation, and (3) develop a simple mathematical model for aerosol levels in the exposure chamber.Methods: We built the system with standard laboratory equipment and an open-source electronics platform (Arduino) for e-cigarette activation. Arduino is used to control a solenoid, which pushes the activation button of so-called "Mod" e-cigarettes, and a pump to move the aerosol from the mouthpiece of the e-cigarette into the chamber. For "Pods" and "Cigalikes," the solenoid is not used as they are activated by the vacuum created by the pump. Aerosol concentrations were measured with a light-scattering laser photometer.Results: The system allows varying the air exchange rate, monitoring aerosol levels, and programing arbitrary puff topography. Aerosol concentrations observed for different chamber operating conditions (puff time and period, e-cigarette power output, air exchange rate) were consistent with the mathematical model.Conclusions: Our low-cost exposure chamber can be used in animal experimental studies of the health effects of e-cigarettes. Our model allows estimating design parameters such as chamber volume, air exchange rate, and puff period.

microRNAs Are Key Regulators in Chronic Lung Disease: Exploring the Vital Link between Disease Progression and Lung Cancer

microRNAs (miRNAs) bind to mRNAs and inhibit their expression through post-transcriptionally regulating gene expression. Here, we elaborate upon the concise summary of the role of miRNAs in carcinogenesis with specific attention to precursor respiratory pathogenesis caused by cigarette smoke modulation of these miRNAs. We review how miRNAs are implicated in cigarette-smoke-driven mechanisms, such as epithelial to mesenchymal transition, autophagy modulation, and lung ageing, which are important in the development of chronic obstructive pulmonary disease and potential progression to lung cancer. Extracellular vesicles are key to inter-cellular communication and sharing of miRNAs. A deeper understanding of the role of miRNAs in chronic respiratory disease and their use as clinical biomarkers has great potential. Therapeutic targeting of miRNAs may significantly benefit the prevention of cancer progression.

Modeling drug exposure in rodents using e-cigarettes and other electronic nicotine delivery systems

Smoking tobacco products is the leading cause of preventable death worldwide. Coordinated efforts have successfully reduced tobacco cigarette smoking in the United States; however, electronic cigarettes (e-cigarette) and other electronic nicotine delivery systems (ENDS) recently have replaced traditional cigarettes for many users. While the clinical risks associated with long-term ENDS use remain unclear, advancements in preclinical rodent models will enhance our understanding of their overall health effects. This review examines the peripheral and central effects of ENDS-mediated exposure to nicotine and other drugs of abuse in rodents and evaluates current techniques for implementing ENDS in preclinical research.

There can be smoke without fire: warranted caution in promoting electronic cigarettes and heat not burn devices as a safer alternative to cigarette smoking

The damaging health effects of active and second-hand cigarette smoking are well documented. Tobacco smoke exposure is the primary cause of COPD, which is estimated to become the third leading cause of global mortality by 2030 [1]. In 2012 it was estimated that 1.8 million new cases of lung cancer occurred globally, making it the most common form of cancer [1]. Maternal smoking and intrauterine exposure to tobacco smoke and nicotine have been linked not only to negative pregnancy outcomes such as miscarriage and preterm birth, but also to numerous adverse pathophysiological outcomes in the child, including an increased risk of developing asthma and COPD due to impaired lung development [2]. The global rates of smoking during pregnancy, particularly in the lower socioeconomic status countries, remain too high [3]. The World Health Organization estimates that in 2015, ∼20% of the world's adult population were current smokers; fortunately, the prevalence of tobacco smoking is on a gradual decline [4]. The tobacco industry is currently changing strategies, shifting the focus from tobacco cigarettes, and promoting the “safer” alternative in electronic cigarettes (e-cigarettes) and now heat not burn (HNB) devices [5]. These devices still deliver nicotine and the rise in the number of dual users (of both traditional cigarettes and e-cigarettes) is alarming [6, 7].

The tobacco industry is now shifting its focus from combustible cigarettes to promoting the “safer” electronic nicotine delivery alternatives. This editorial presents emerging challenges these devices pose to human health.http://bit.ly/2xdAjD0