Dataset Information

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

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

SUBMITTER: Rowell TR

PROVIDER: S-EPMC7052665 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Flavored e-liquids increase cytoplasmic Ca<sup>2+</sup> levels in airway epithelia.

Rowell Temperance R TR Keating James E JE Zorn Bryan T BT Glish Gary L GL Shears Stephen B SB Tarran Robert R

American journal of physiology. Lung cellular and molecular physiology 20191106 2

E-cigarettes are noncombustible, electronic nicotine-delivery devices that aerosolize an e-liquid, i.e., nicotine, in a propylene glycol-vegetable glycerin vehicle that also contains flavors. While the effects of nicotine are relatively well understood, more information regarding the potential biological effects of the other e-liquid constituents is needed. This is a serious concern, because e-liquids are available in >7,000 distinct flavors. We previously demonstrated that many e-liquids affect ...[more]

PMID: 31693394

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Project description:Cigarette smoking is associated with chronic obstructive pulmonary disease and chronic bronchitis. Acquired ion transport abnormalities, including cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction, caused by cigarette smoking have been proposed as potential mechanisms for mucus obstruction in chronic bronchitis. Although e-cigarette use is popular and perceived to be safe, whether it harms the airways via mechanisms altering ion transport remains unclear. In the present study, we sought to determine if e-cigarette vapor, like cigarette smoke, has the potential to induce acquired CFTR dysfunction, and to what degree. Electrophysiological methods demonstrated reduced chloride transport caused by vaporized e-cigarette liquid or vegetable glycerin at various exposures (30 min, 57.2% and 14.4% respectively, vs. control; P < 0.0001), but not by unvaporized liquid (60 min, 17.6% vs. untreated), indicating that thermal degradation of these products is required to induce the observed defects. We also observed reduced ATP-dependent responses (-10.8 ± 3.0 vs. -18.8 ± 5.1 μA/cm2 control) and epithelial sodium channel activity (95.8% reduction) in primary human bronchial epithelial cells after 5 minutes, suggesting that exposures dramatically inhibit epithelial ion transport beyond CFTR, even without diminished transepithelial resistance or cytotoxicity. Vaporizing e-cigarette liquid produced reactive aldehydes, including acrolein (shown to induce acquired CFTR dysfunction), as quantified by mass spectrometry, demonstrating that respiratory toxicants in cigarette smoke can also be found in e-cigarette vapor (30 min air, 224.5 ± 15.99; unvaporized liquid, 284.8 ± 35.03; vapor, 54,468 ± 3,908 ng/ml; P < 0.0001). E-cigarettes can induce ion channel dysfunction in airway epithelial cells, partly through acrolein production. These findings indicate a heretofore unknown toxicity of e-cigarette use known to be associated with chronic bronchitis onset and progression, as well as with chronic obstructive pulmonary disease severity.

Project description:Mutations in thin filament regulatory proteins that cause hypertrophic cardiomyopathy (HCM) increase myofilament Ca2+ sensitivity. Mouse models exhibit increased Ca2+ buffering and arrhythmias, and we hypothesized that these changes are primary effects of the mutations (independent of compensatory changes) and that increased Ca2+ buffering and altered Ca2+ handling contribute to HCM pathogenesis via activation of Ca2+-dependent signaling. Here, we determined the primary effects of HCM mutations on intracellular Ca2+ handling and Ca2+-dependent signaling in a model system possessing Ca2+-handling mechanisms and contractile protein isoforms closely mirroring the human environment in the absence of potentially confounding remodeling. Using adenovirus, we expressed HCM-causing variants of human troponin-T, troponin-I, and α-tropomyosin (R92Q, R145G, and D175N, respectively) in isolated guinea pig left ventricular cardiomyocytes. After 48 h, each variant had localized to the I-band and comprised ∼50% of the total protein. HCM mutations significantly lowered the Kd of Ca2+ binding, resulting in higher Ca2+ buffering of mutant cardiomyocytes. We observed increased diastolic [Ca2+] and slowed Ca2+ reuptake, coupled with a significant decrease in basal sarcomere length and slowed relaxation. HCM mutant cells had higher sodium/calcium exchanger activity, sarcoplasmic reticulum Ca2+ load, and sarcoplasmic/endoplasmic reticulum calcium ATPase 2 (SERCA2) activity driven by Ca2+/calmodulin-dependent protein kinase II (CaMKII) phosphorylation of phospholamban. The ryanodine receptor (RyR) leak/load relationship was also increased, driven by CaMKII-mediated RyR phosphorylation. Altered Ca2+ homeostasis also increased signaling via both calcineurin/NFAT and extracellular signal-regulated kinase pathways. Altered myofilament Ca2+ buffering is the primary initiator of signaling cascades, indicating that directly targeting myofilament Ca2+ sensitivity provides an attractive therapeutic approach in HCM.

Project description:IntroductionSugars are major constituents and additives in traditional tobacco products, but little is known about their content or related toxins (formaldehyde, acetaldehyde, and acrolein) in electronic cigarette (e-cigarette) liquids. This study quantified levels of sugars and aldehydes in e-cigarette liquids across brands, flavors, and nicotine concentrations (n = 66).MethodsUnheated e-cigarette liquids were analyzed using liquid chromatography mass spectrometry and enzymatic test kits. Generalized linear models, Fisher's exact test, and Pearson's correlation coefficient assessed sugar, aldehyde, and nicotine concentration associations.ResultsGlucose, fructose and sucrose levels exceeded the limits of quantification in 22%, 53% and 53% of the samples. Sucrose levels were significantly higher than glucose [χ2(1) = 85.9, p < .0001] and fructose [χ2(1) = 10.6, p = .001] levels. Formaldehyde, acetaldehyde, and acrolein levels exceeded the limits of quantification in 72%, 84%, and 75% of the samples. Acetaldehyde levels were significantly higher than formaldehyde [χ2(1) = 11.7, p = .0006] and acrolein [χ2(1) = 119.5, p < .0001] levels. Differences between nicotine-based and zero-nicotine labeled e-cigarette liquids were not statistically significant for sugars or aldehydes. We found significant correlations between formaldehyde and fructose (-0.22, p = .004) and sucrose (-0.25, p = .002) and acrolein and fructose (-0.26, p = .0006) and sucrose (-0.21, p = .0006). There were no significant correlations between acetaldehyde and any of the sugars or any of the aldehydes and glucose.ConclusionsSugars and related aldehydes were identified in unheated e-cigarette liquids and their composition may influence experimentation in naïve users and their potential toxicity.ImplicationsThe data can inform the regulation of specific flavor constituents in tobacco products as a strategy to protect young people from using e-cigarettes, while balancing FDA's interest in how these emerging products could potentially benefit adult smokers who are seeking to safely quit cigarette smoking. The data can also be used to educate consumers about ingredients in products that may contain nicotine and inform future FDA regulatory policies related to product standards and accurate and comprehensible labeling of e-cigarette liquids.

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

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Flavored e-liquids increase cytoplasmic Ca<sup>2+</sup> levels in airway epithelia.

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

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Flavored e-liquids increase cytoplasmic Ca&lt;sup&gt;2+&lt;/sup&gt; levels in airway epithelia.

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

Flavored e-liquids increase cytoplasmic Ca<sup>2+</sup> levels in airway epithelia.