The lung microbiome after lung transplantation

Abstract

Lung transplantation survival remains significantly impacted by infections and the development of chronic rejection manifesting as bronchiolitis obliterans syndrome (BOS). Traditional microbiologic data has provided insight into the role of infections in BOS. Now, new non-culture-based techniques have been developed to characterize the entire population of microbes resident on the surfaces of the body, also known as the human microbiome. Early studies have identified that lung transplant patients have a different lung microbiome and have demonstrated the important finding that the transplant lung microbiome changes over time. Furthermore, both unique bacterial populations and longitudinal changes in the lung microbiome have now been suggested to play a role in the development of BOS. In the future, this technology will need to be combined with functional assays and assessment of the immune responses in the lung to help further explain the microbiome's role in the failing lung allograft.

Keywords::

• bacterial infections
• bronchiolitis obliterans syndrome
• fungome
• lung transplant
• microbiome
• viral infections
• virome

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• New non-culture-based techniques use DNA sequencing to identify entire microbial populations on the surfaces of the body, and these techniques are beginning to be applied to the lung transplant recipients.

• Infections and bronchiolitis obliterans syndrome (BOS) are the major causes of death in lung transplant recipients. Studies of the lung allograft microbiome may provide a new understanding of these complications and a target for therapy.

• The microbiota in the lung transplant recipient differs from that of healthy control patients. However, the driving force behind this difference and the prognostic implications of these differences are unclear.

• The development of BOS has been strongly linked to bacteria, viral and fungal infections in traditional microbiological studies. Current analyses of the lung microbiome suggest that there are important differences between lung transplant recipients with and without BOS. The significance of these differences needs further investigation.

• Major future directions include understanding the interaction between different microbial populations and the human immune system and harnessing microbiome analysis as a prognostic tool and therapeutic target.

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