The lung microbiome and transplantation.

PURPOSE OF REVIEW: Lung transplantation survival is still limited compared with other solid organ transplant modalities, due to a range of factors that are continuing to be elucidated. However, new research is emerging which indicates that the microbiome of the lungs, and of other organs, may have important implications for immune response and mediating transplant outcomes. Pathogenic bacterial and viral species are known to have deleterious effects on the allograft, but taking a more global view, and considering the overall composition of the community of microbial species may undercover a greater understanding of the complex interplay involved in allograft dysfunction.

RECENT FINDINGS: The microbiome appears to have an important modulatory role on immune response in both normal development, and after transplantation. A range of microbial species contributes to the resident microscopic community, with the gut and blood microbiomes having a significant impact on the function of the lungs and resistance to infection. Movement of species from within and outside the respiratory tract occurs in the early transplant period, leading to a modified donor microbiome in the recipient. There is evidence to suggest that chronic lung allograft dysfunction may be facilitated by the respiratory microbiome and interactions with immune cells within the allograft.

SUMMARY: Further investigation of the respiratory microbiome, interactions with the microbiome of other organs and impact on immune and allograft function posttransplantation is needed. Promising insights are being gained regarding certain microbial profiles which may be associated with negative outcomes, and the mechanisms through which this occurs. As our understanding expands, the ability to modify the microbiome offers novel treatment strategies for combating allograft dysfunction.