Effects of smoking on the lower respiratory tract microbiome in mice

Abstract

BackgroundRecent studies break with traditional opinion that the lower respiratory tract is sterile, and increasingly focus on the lung microbiome and disease. Smoking, as an important etiology of inflammatory lung disease, was considered as a factor influencing lung microbiome variations in our study, and we aimed to study the effect of smoking on inflammation and microbial diversity and community.MethodsForty male mice were selected and randomly divided into a smoking and a non-smoking group. Mice in the smoking group were exposed to smoke smog for 2 h/day for 90 days. Blood and lung tissues were obtained after the experiment, and ELISA was used to measure interleukin-6 and C reactive protein concentrations. 16S rRNA gene quantification and sequencing technology were used to compare microbial diversity and community between the two groups. SAS 9.1 and R software were used to analyze the data.ResultsThirty-six mice survived, and the weight of the smoking group increased more slowly than that of the non-smoking group. Denser inflammation and congestion were observed in the lungs of the smoking mice compared with the non-smoking group Higher microbial diversity was observed in the smoking group, and Enterobacter, Acidimicrobiales_norank, and Caulobacteraceae_Unclassified genus were significantly more abundant in the non-smoking group (P < 0.001).ConclusionsSmoking altered microbial diversities and communities in the lower respiratory tract of mice. Microbial variation should be considered in future studies focusing on smoking-induced inflammatory disease.

The lung microbiome: clinical and therapeutic implications

“…In recent years, it has been shown that the lungs of healthy smokers contain a bacterial microbiome that is quantitatively and qualitatively diverse from that of the oral cavity and extra-thoracic airways [43]. However, the role of microbial diversity remains unclear, since in contrast with Zhang et al [42], human LMt diversity is often lower in subjects with poor lung function, and it is most commonly associated with dominance by Pseudomonas spp. The fact that some smokers, with spirometric evidence of lung disease, had a less different LMt compared with smokers, with normal lung function, and indicates that LMt changes can be an earlier sign of respiratory disease [43].…”

“…These substances contact the respiratory mucosa and are associated with chronic inflammation in smokers. Recently, Zhang et al [42] studied that 40 mice exposed to tobacco smoke and observed that microbial diversity was higher in the smoking group, suggesting that smoke exposure increases the risk of bacterial infection, thereby increasing microbial diversity. The authors concluded that smoking influences microbial diversity and communities of the lower respiratory tract, suggesting that future studies on smoke-induced inflammation should also consider the LMt variation [42].…”

“…Recently, Zhang et al [42] studied that 40 mice exposed to tobacco smoke and observed that microbial diversity was higher in the smoking group, suggesting that smoke exposure increases the risk of bacterial infection, thereby increasing microbial diversity. The authors concluded that smoking influences microbial diversity and communities of the lower respiratory tract, suggesting that future studies on smoke-induced inflammation should also consider the LMt variation [42]. In recent years, it has been shown that the lungs of healthy smokers contain a bacterial microbiome that is quantitatively and qualitatively diverse from that of the oral cavity and extra-thoracic airways [43].…”

The lung microbiota: role in maintaining pulmonary immune homeostasis and its implications in cancer development and therapy

“…Moreover, Munck et al reported the lack of important changes in bacterial diversity after smoking cessation [83], indicating that smoking does not have a key role in determining modifications in lung commensal composition. On the other hand, studies performed in humans [74] and mice [84] suggested that smoke exposure can alter bacterial composition in the lower respiratory tract, probably by impairing local immune cell activity. Since chemical compounds present in the tobacco smoke may affect lung immune cells function [85,86], smoking may determine a disequilibrium in the microbiota-immune cell cross talk, leading to dysbiosis, chronic infection and, eventually, lung cancer.…”

Effects of respiratory disease on Kele piglets lung microbiome, assessed through 16S rRNA sequencing

“…Overall, the dominant microorganisms at the phylum level in healthy pig lungs were Proteobacteria , Firmicutes , and Bacteroidetes , which are similar to the lung microorganisms present in humans [ 12 , 34 ], mice [ 35 , 36 ], and cattle [ 21 , 37 ]. This finding indicates that the composition of lung microorganisms in healthy individuals of different species is comparable.…”