The respiratory microbiome after lung transplantation: Reflection or driver of respiratory disease?

Abstract

With the introduction of high-throughput sequencing methods, our understanding of the human lower respiratory tract's inhabitants has expanded significantly in recent years. What is now termed the "lung microbiome" has been described for healthy patients, as well as people with chronic lung diseases and lung transplants. The lung microbiome of lung transplant recipients (LTRs) has proven to be unique compared with nontransplant patients, with characteristic findings associated with disease states, such as pneumonia, acute rejection, and graft failure. In this review, we summarize the current understanding of the lung microbiome in LTRs, not only focusing on bacteria but also highlighting key findings of the viral and the fungal community. Based on our knowledge of the lung microbiome in LTRs, we propose multiple opportunities for clinical use of the microbiome to improve outcomes in this population.

Keywords: infectious disease; lung transplantation/pulmonology; lung transplantation: living donor; microbiome; translational research/science.

Figure 1.. Risk of bronchiolitis obliterans syndrome based on lung microbiota.

A) A cystic fibrosis (CF) patient maintains colonization with Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) after lung transplantation and does not develop bronchiolitis obliterans syndrome (BOS). B) A CF patient with BOS demonstrates post-transplant microbiota with Streptococcus and Veillonella, distinct from pre-transplant colonizers of PA and SA. C) A Non-CF patient develops BOS after de novo acquisition of PA and SA after transplantation.