Background

Lung transplantation outcomes remain complicated by bronchiolitis obliterans syndrome (BOS), a major cause of mortality and retransplantation for patients. A variety of factors linking inflammation and BOS have emerged, meriting further exploration of the microbiome as a source of inflammation. In this analysis, we determined features of the pulmonary microbiome associated with BOS susceptibility.

Methods

Bronchoalveolar lavage (BAL) samples were collected from 25 patients during standard of care bronchoscopies before BOS onset. Microbial DNA was isolated from BAL fluid and prepared for metagenomics shotgun sequencing. Patient microbiomes were phenotyped using k-means clustering and compared to determine effects on BOS-free survival.

Results

Clustering identified 3 microbiome phenotypes: Actinobacteria dominant (AD), mixed, and Proteobacteria dominant. AD microbiomes, distinguished by enrichment with Gram-positive organisms, conferred reduced odds and risks for patients to develop acute rejection and BOS compared with non-AD microbiomes. These findings were independent of treatment models. Microbiome findings were correlated with BAL cell counts and polymorphonuclear cell percentages.

Conclusions

In some populations, features of the microbiome may be used to assess BOS susceptibility. Namely, a Gram-positive enriched pulmonary microbiome may predict resilience to BOS.

Health disparities are prevalent across diseases of the respiratory system, and are major sources of morbidity and mortality among disadvantaged populations in the United States. The American Thoracic Society (ATS) aims to reduce disparities that are both avoidable and unjust. In meeting this goal, the ATS is committed to creating the Lung Corps, a diverse group of senior, mid-level, and junior clinicians, trainees, researchers, and public health practitioners to help achieve health equality. This will be achieved through the following mechanisms: (1) increase awareness of health disparities; (2) empower health professionals with the knowledge and tools to address disparities; (3) shape research agendas to focus on the root causes, to identify modifiable targets, and to promote innovative approaches to reduce disparities; and (4) develop and advocate for health-related policies and regulations that improve the respiratory health of the population. To ensure success, the Lung Corps will interact with other societies, agencies, and organizations to effect elimination of disparities in respiratory health. The ATS is committed to identifying and addressing health disparities to improve the overall health of individuals affected by respiratory diseases.