Since the emergence of the concept of exposome biology in 2005, attention has focused on the influence of specific environmental factors on human health, among which e-cigarettes occupy a growing place. Battery-powered devices, e-cigarettes heat a mixture of humectants, flavoring agents, and sometimes nicotine, generating an aerosol that is inhaled by the user. Since their introduction on the American market some fifteen years ago, these devices have experienced a meteoric rise, with sales increasing by 46,6% between 2020 and 2022.
However, recent studies reveal that e-cigarettes significantly alter human pathophysiology, particularly by affecting the cardiovascular and respiratory systems. The oral orifice, the first point of contact with the aerosol, is particularly affected by these exposures, with an increase in virulence signatures and inflammatory signals in vapers, even those in good clinical health.
Study objectives
In this study, researchers explored how oral bacteria interact with e-cigarette aerosols, assessing structural and functional changes in the oral microbiota. The methodology combined untargeted metabolomics, metatranscriptomics, and fluorescent microscopy, with validation using human samples.
Results
Chemical analysis using gas chromatography-mass spectrometry revealed more than 300 compounds in nicotine- and non-nicotine-based aerosols, with less than half in common. The substances detected included molecules with suspected high cytotoxicity, such as paraldehyde, acetyl chloride, and fluoroacetic acid.
Using spectral deconvolution, 969 metabolites were identified, distributed across 23 distinct metabolic pathways. Metabolites varied depending on aerosol characteristics and biofilm composition. Profound alterations in biofilm architecture were observed, including increased biomass, reduced surface-to-volume ratio, and increased diffusion distances.
At the functional level, aerosol exposure stimulated xenobiotic degradation, capsule and peptidoglycan biosynthesis, and organic carbon-based compound metabolism. It also promoted the emergence of antimicrobial resistance systems and secretion mechanisms.
Human analyses corroborated these observations, confirming the presence of aerosol-derived metabolites in the saliva of vapers.
Conclusion
The data collected show that oral bacteria actively metabolize e-cigarette aerosols, triggering a stress response regulated by quorum sensing. This dynamic promotes the formation of dense, exopolysaccharide-rich biofilms in communities previously compatible with health, while amplifying virulence and antibiotic resistance in pathogenic environments. This work underscores the critical importance of assessing the impact of vaping not only on human cells, but also on host microbiomes.
