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Effects of Electronic Cigarette Constituents on the Human Lung: A Pilot Clinical Trial [expression]

ABSTRACT: E-cig use is continuing to increase, particularly among youth never-smokers, and is used by some smokers to quit. The acute and chronic toxicity of e-cig use is unclear generally in the context of increasing reports of inflammatory-type pneumonia in some e-cig users. To assess lung effects of e-cigs without nicotine or flavors, we conducted a pilot study with serial bronchoscopies over 4 weeks in 30 never-smokers, randomized either to a four-week intervention with the use of e-cigs containing only 50% propylene glycol (PG) and 50% vegetable glycerine (VG) or to a no-use control group. Compliance to the e-cig intervention was assessed by participants sending daily puff counts and by urinary propylene glycol (PG). Inflammatory cell counts and cytokines were determined in bronchoalveolar lavage (BAL) fluids. Genome-wide expression, microRNA, and mRNA were determined from bronchial epithelial cells. There were no significant differences in changes of BAL inflammatory cell counts or cytokines between baseline and follow-up, comparing the control and e-cig groups. However, in the intervention but not the control group, change in urinary PG as a marker of e-cig use and inhalation, was significantly correlated with change in cell counts (cell concentrations, macrophages, and lymphocytes) and cytokines (IL-8, IL-13, and TNF-α), although the absolute magnitude of changes was small. There were no significant changes in mRNA or microRNA gene expression. Although limited by study size and duration, this is the first experimental demonstration of an impact of e-cig use on inflammation in the human lung among never-smokers.

ORGANISM(S): Homo sapiens

PROVIDER: GSE138326 | GEO | 2020/01/14

REPOSITORIES: GEO

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Project description:Propylene glycol (PG) is a common carrier in e-vapor formulations and its properties have been extensively studied. In this 13-week subchronic nose-only inhalation study, Sprague Dawley rats were exposed to filtered air (sham control group), propylene glycol/water (PG/W; 90:10) or a propylene glycol/vegetable glycerin/water (PG/VG/W; 50:40:10) reference. The reference containing vegetable glycerin group was added at the high dose to observe any changes that might be associated with a carrier more in line with e-vapor products. The objectives of this study were to increase the PG exposure above the concentrations tested by Suber et al. and use a systems toxicology analysis of lung tissue to further our understanding of molecular events after PG exposures (Suber et al. 1989). Macroscopic examinations at necropsy as well as terminal organ weights revealed no observations that were associated with exposure to PG/W or reference. Food consumption and body weights were unaffected by PG/W or reference when compared to the sham. No exposure related alterations were observed in serum chemistry, hematology, coagulation, urinalysis or BALF cytology and clinical chemistry. Although clinical observations of dried red material around the nose in the high dose PG/W group were reported, histopathology of the nasal cavity showed no nasal hemorrhaging. There were non-adverse PG/W and reference related findings of minimal mucus cell hyperplasia noted in nasal cavity section II. These findings were considered non-adverse as they were also found to a lesser extent in the filtered air controls. No other exposure-related findings were noted in the primary or recovery necropsies. A systems toxicology analysis on lung tissue showed no statistically-significant differentially expressed transcripts or proteins compared to the sham group. The endpoints measured from the PG/W high dose group did not differ significantly from those in the more common carrier PG/VG/W. Accordingly, the highest PG exposure (5 mg/L, 6 hrs/day) was regarded as the no observed adverse effect concentration (NOAEC), corresponding to a PG delivered dose of 1,152 mg/kg/day in rats.

Project description:Background: Adult vapers are likely to co-use electronic cigarettes (e-cigs) and combustible cigarettes or have a prior history of smoking. Teasing out the health consequences of vaping in adults, while accounting for the confounding effects of smoking, remains a research priority. Methods: We have segregated the biological effects of vaping from smoking by constructing the whole transcriptome in leukocytes of healthy adult vapers (with and without a history of smoking) and exclusive smokers in comparison to control nonsmokers non-vapers (n = 37, 22, 23, respectively). Results: Age- and sex-adjusted limmaVoom analysis of RNA-seq data showed significant dysregulation of key genes and molecular pathways in both vapers and smokers as compared to controls. The extent of transcriptomic effects, as reflected by the number of differentially expressed genes, was more pronounced in smokers than vapers (683 vs. 92). Computational modeling, combining primary and sensitivity analyses, revealed that e-cig use, but not past smoking, is significantly associated with gene dysregulation in vapers. Comparative analysis of the gene networks and canonical pathways impacted in vapers and smokers showed strikingly similar biological outcomes in the two groups, although the number of affected genes was several-fold higher in smokers than vapers. Of significance is the preferential targeting of mitochondrial genes in both vapers and smokers, consistent with impaired functional networks, which are known to drive mitochondrial DNA-related disorders. Equally remarkable is the dysregulation of immune response genes in both vapers and smokers, modulated by upstream cytokines, including members of the interleukin and interferon family, that play a crucial role in inflammation. Conclusions: The concurrent targeting of mitochondrial- and immune response genes in vapers and smokers suggests a consequential role for vaping and smoking in inflammation. Our findings accord with the growing evidence on the central role of mitochondria as signaling organelles that govern fundamentals of immunity and inflammatory response. In view of the widespread use of e-cigs among youth and young adults, these novel findings have significant implications for tobacco regulatory science and public health.

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Effects of Electronic Cigarette Constituents on the Human Lung: A Pilot Clinical Trial [expression]

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