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Lung microbiome quantification and bacterial density as prognostic markers in lung transplantation
Jessica Santilli1, Elaine Reguera-Nuñez2, Eric Armstrong2
1Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada; Toronto General Hospital Research Institute, University Health Network, Toronto, Canada.
Summary
Measuring absolute bacterial abundance in the lung allograft microbiome, not just relative abundance, improves the identification of chronic lung allograft dysfunction (CLAD). This approach enhances understanding of how the lung microbiome impacts transplant outcomes.
Area of Science:
- Microbiology
- Transplantation immunology
- Genomics
Background:
- Chronic lung allograft dysfunction (CLAD) significantly impacts long-term lung transplant survival.
- Previous studies focused on relative bacterial abundance in the lung allograft microbiome, limiting insights into host-microbe interactions.
- Absolute bacterial quantitation offers a more comprehensive assessment of microbiome dynamics.
Purpose of the Study:
- To compare lung allograft microbiome composition and bacterial absolute abundance between CLAD cases and controls.
- To evaluate the performance of absolute bacterial quantitation versus compositional indices in identifying CLAD-associated microbiomes.
Main Methods:
- A case-control study involving 53 CLAD cases and 55 CLAD-free controls.
- Bronchoalveolar lavage fluid collected within 12 months post-transplantation.
- Analysis of microbiome composition and absolute bacterial abundance.
Main Results:
- Five overlapping lung allograft microbiome community state types (CSTs) were identified, dominated by specific bacterial genera (Prevotella, Streptococcus, Neisseria, Staphylococcus, Pseudomonas) or diverse bacteria.
- Lower bacterial density was observed in taxonomically diverse communities and was lower in controls than cases.
- Normalizing relative abundance to total bacterial density strengthened microbiome-CLAD associations.
Conclusions:
- Absolute bacterial quantification enhances the association between the lung microbiome and CLAD.
- This method may improve the understanding of lung microbiome's role in lung transplant outcomes.
