Nicotine-free and Nicotine-containing E-cigarettes Differentially Alter Microbial Colonization Dynamics
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Date
2020-02
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Abstract
E-cigarettes have maintained popularity due to the perception that they are safe. However, there is limited evidence as to their long-term effects. The goal of the present investigation was to investigate the longitudinal effects of e-cigarette aerosol on oral bacterial colonization dynamics. Sterilized hydroxyapatite discs were incubated in artificial saliva for 24 hours to establish a pellicle coat, following which six pioneer species were seeded and incubated aerobically. Pathogen-rich biofilms were created by further seeding the commensal biofilms with an intermediate colonizer (Fusobacterium nucleatum), followed 24 hours later by eight pathogens and incubating anaerobically. Biofilms were created under three conditions: nicotine-containing e-cigarette aerosol, nicotine-free e-cigarette aerosol and controls. Biofilms were imaged with confocal and scanning electron microscopy. Surface area and volume were quantified with LiveDead stain and analyzed with Imaris. RNA was isolated, mRNA enriched, then sequenced and aligned. Aligned sequences were annotated to the KEGG and SEED databases using MEGAN6. Significant differences (Dunn's test, p<0.001) were observed in both surface area and volume measurements, where e-cigarette exposed biofilms were significantly larger. Significant differences (PERMANOVA, p<0.05) in gene regulation were observed between e-cigarette and control groups at all levels of biofilm development. E-cigarette groups showed higher abundances of cell wall and capsule synthesis genes, which suggests a likely explanation for the increases observed in biofilm surface area and volume. This has important implications for understanding the risks of long-term e-cigarette use especially in the context of dental diseases.
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Poster Division: Health Sciences: 1st Place (The Ohio State University Edward F. Hayes Graduate Research Forum)
Keywords
microbiome, e-cigarette, metatranscriptomics, ENDS, oral microbiome