New insights on the pulmonary mycobiome
Click Here to Manage Email Alerts
In a new study, researchers observed differences in taxonomic composition and diversity of oral and pulmonary samples from patients with and without COPD, which may indicate the existence of a pulmonary mycobiome.
“Healthy airways possess effective removal of such spores through mucociliary clearance and phagocytosis. In contract, impaired defense mechanisms, use of immunosuppressant and frequent use of antibiotics probably predispose for increased fungal growth, and all factors are quite frequent in COPD,” Einar M. H. Martinsen, MD, PhD candidate in the department of clinical science at the University of Bergen in Norway, and colleagues wrote in PLOS ONE. “The fungal part of the microbiome, the mycobiome, of the lungs is understudied, and only three studies have used next-generation sequencing to study the mycobiome of the respiratory tract in COPD particularly.”
Researchers conducted the single-center, observational Bergen COPD Microbiome study, which enrolled 93 participants with COPD (mean age, 67.5 years; 53.8% men) and 100 controls without COPD (mean age, 65.6 years; 57% men). Researchers collected oral wash and bronchoalveolar lavage from each participant and extracted fungal DNA before sequencing fungal ribosomal RNA gene clusters.
“Results showed that both healthy and diseased lungs had a different fungal composition than the mouth, suggesting that lungs have a unique fungal environment,” Martinsen said in a press release.
Among participants with COPD and controls, oral and pulmonary mycobiomes were dominated by Candida, the researchers reported. Researchers observed more Candida among oral samples compared with bronchoalveolar lavage for participants with COPD and control, according to the results.
In pulmonary samples, Malassezia and Sarocladium were frequently observed among both participant groups.
The researchers reported no differences in abundance or distribution between the two groups. Alpha and beta diversity were not different in pulmonary samples between both participant groups; however, there was variation in beta diversity depending on sample type, according to the results.
In other results, patients with COPD using inhaled corticosteroids did not have any difference in the fungal community of their lungs compared with those who did not use inhaled corticosteroids.
According to the researchers, these findings should be confirmed in future studies before concluding that inhaled corticosteroid use causes no harm to the lung mycobiome.
“Studies on the lung mycobiome are still in their infancy, and results from the current study add knowledge to an understudied area,” the researchers wrote.
The researchers are currently assessing whether fungi are present in other lung diseases.
“It would be of great interest to further examine if fungal lung infections are caused by fungi that are already present in the lungs,” Martinsen said in the release. “If so, emphasis should be placed on these fungi to reveal what triggers are responsible for converting them from being ‘friendly residents’ of our lungs to disease-causing intruders.”