The Effects of Electronic Cigarettes on Oral Microbiome and Metabolome in 3D Tissue-Engineered Models

Recent studies have shown that electronic cigarettes (ECs) use disrupts the oral microbiome composition and diversity, impairing the metabolic pathways of the mucosal cells. However, to date, no reports have evaluated the role of EC exposure in the context of oral metabolome. Hence, the aim of this study was to investigate the role of EC aerosol exposure in the dysregulation of the oral microbiome and metabolome profile using in vitro 3D organotypic models of human oral mucosa. 3D tissue-engineered human oral mucosa models were generated and infected with oral microbes obtained from saliva of a healthy donor. The epithelial surface of the oral mucosal models was exposed directly to the EC aerosol (flavoured; with and without nicotine) as it came out of a simulated activated device that mimicked the clinical situation. A comprehensive assessment of oral microbiome community composition by bacterial 16S rRNA gene sequencing was performed. A gas chromatography-based mass spectrometry analysis was also conducted to identify the effect of vaping on the oral metabolome profile. A higher alpha diversity in flavoured EC with nicotine groups was observed compared to controls, with notable differences in bacterial taxa abundance. Metabolomics analysis further demonstrated distinct clustering of control, EC with flavoured nicotine, and flavoured EC groups, confirming 13 metabolites that were statistically higher in levels in flavoured EC with nicotine group, indicating the adverse effects of nicotine on the oral mucosa model. Altered metabolites were mainly enriched in pathways associated with oral cancer progression. This study underscores the significant impact of EC use on oral health, highlighting alterations in the oral microbiome, bacterial composition, and metabolite profiles via a clinically relevant in vitro 3D organotypic model of human oral mucosa.