Exposure to aerosols produced by vaping devices cause changes in the respiratory microbiota of mice

From our mouth and nose to the bottom of our lungs, our respiratory system shelters many diverse and complex populations of microbes that are highly affected by the quality of air we breath.
Current knowledge supports the role of respiratory microbiota in excluding pathogens and training the immune system. In fact, disruption of the microbiota or dysbiosis has been associated to several lung diseases such as COPD and asthma, supporting a bidirectional relationship between airway dysbiosis and lung diseases. Therefore, maintaining a diverse and balanced respiratory microbiota is crucial.
Vaping has recently become a widespread habit. However, very few studies have looked at the impacts that inhaling the aerosols it produces has on the respiratory system, particularly the respiratory microbiota. Many flavouring chemicals used in vaping have antimicrobial properties, making them toxic to bacteria. Since airborne pollutants are known to have an influence on the composition of the respiratory microbiota, exposure to the aerosolized antimicrobial chemicals of vaping liquids could cause unknown changes to respiratory microbial populations.
Here, we show that most ingredients used in vaping liquids have an antimicrobial effect on cultured bacteria and their impact is not equal on all species of bacteria. Some flavouring chemicals are more potent like cinnamaldehyde (cinnamon) and eugenol (cloves). Others have weaker effects like 2,5-dimethypyrazine (hazelnut) and ethyl butyrate (fruity). We show that mice exposed to vaping aerosols will have their oral bacteria populations altered by a significant increase in diversity and changes in their composition. In contrast, vaping aerosols with strong antimicrobial flavours causes a significant decrease in lung microbiota diversity. Finally, we show that the toxic properties of vaping aerosols can disrupt the respiratory microbiota. These changes need to be further studied in human in order to fully understand the impact of vaping on public health.