The lungs were once believed to be a sterile environment, but in recent years, metagenomics studies confirmed the presence of commensal bacteria in the lungs of healthy individuals. The lungs or lower respiratory tract is linked to the upper respiratory tract and the oral cavity, and several studies have reported that the microbes in the nasal and oral cavity are involved in the formation of the lung microbiota. However, the process still remains unclear for lack of quantitative ecological knowledge and explanation of individual differences.

A recent research article, published in Advanced Science by the joint team of Prof. Tao Ding and Prof. Guo-Bao Tian from Zhongshan School of Medicine (ZSSOM) of Sun Yat-sen University, finds that oral microbes contributed to most of the dominant taxa in the lungs, but these contributions were highly heterogeneous. This individual heterogeneity determined two microbiota pnuemo-types, the characteristics of which were closely associated with host lung health.

In this study, the research team enrolled 67 patients with lung cancer and 32 volunteers with non-malignant lung diseases and profiled the microbiomes of the saliva, nasal cavity, oropharyngeal area and the bronchoalveolar lavage samples. By integrating multi-omics informatics techniques and statistical modeling, the team found that oral and nasal microbial input jointly shaped the lung microbiota by occupying different ecological niches. The team observed that spread of oral microbes to the lungs were heterogeneous and identified two microbiota pneumo-types, high oral input type (HOIT) and low oral input type (LOIT). They found that in the group of HOIT, there are more of oral microbes entering the lungs with decreased lung function and increased lung proinflammatory cytokines.

Differential oral microbial input determines two microbiota pneumo-types associated with health status.

These results depict the external shaping process of lung microbiota, and indicate the great value of oral samples such as saliva in monitoring and assessing lung microbiota status in clinical settings.

Ph.D student Jingxiang Zhang (ZSSOM), Master student Yiping Wu (ZSSOM), Professor/Chief Physician Jing Liu (The Fifth Affiliated Hospital) and Post-doc Yongqiang Yang (ZSSOM) are co-first authors of the paper. Professors Tao Ding and Guo-Bao Tian are the co-corresponding authors.

Link to the paper: https://onlinelibrary.wiley.com/doi/10.1002/advs.202203115