A recent study published in Access Microbiology sheds light on the composition of the microbiome and its interactions in the lower respiratory tract (LRT) in smokers. The impact of smoking on resident microbial communities in the body has been well-documented, with previous studies proposing mechanisms such as immunosuppression related to smoking and a selection of species by local oxygen tension. The upper airways and oral cavities may also interact with smoking chemicals, microbes, and heat from cigarettes, which can alter microbiome content. Dysbiosis in the oral microbiome related to smoking has been hypothesized to lead to a greater likelihood of experiencing respiratory tract complications among smokers.
In the present study, researchers compared the LRT microbiome profiles of active smokers (AS), former smokers (FS), and non-smokers (NS) to describe the bacterial communities present in the lung. Volunteer subjects aged over 40 years who were either smokers of a minimum of 10 pack-years throughout their life or non-smokers were included. Former smokers qualified for the study if they had abstained from using tobacco for a minimum of 12 months, while AS smoked a minimum of one cigarette within three days of recruitment. All study participants completed a pulmonary function examination and thorough demographic and clinical questionnaire. The team extracted total DNA from the bronchoalveolar lavages (BALs) specimens and conducted a single PCR assessment to amplify the V6-V8 region present on the 16S rRNA gene from the metagenomic DNA extracts of the BAL samples. The study found that smoking alters the lung microbiome and leads to a loss of diversity and community structure.
The study also observed that the oral microbiota can settle in the lungs of smokers, making the study of the upper airway microbiome interesting for future research. Former smokers exhibited similar properties to both AS and NS, suggesting that quitting smoking can partially reverse the effects on the LRT microbiome. The results of this study provide new insights into the complicated microbial communities found in the LRT and how the microbiome can be changed under different smoking conditions. Integration of these findings with next-generation analytical techniques would help establish the effect of such microbial communities on human health.
