Accumulating evidence suggests that the upper airway bacterial microbiota is implicated in asthma inception, severity, and exacerbation. Unlike bacterial microbiota, the role of the upper airway fungal microbiome (mycobiome) in asthma control is poorly understood.
What are the upper-airway fungal colonization patterns among asthmatic children and their relationship with subsequent loss of asthma control and exacerbation of asthma?
The study was coupled with the Step Up Yellow Zone Inhaled Corticosteroids to Prevent Exacerbations (STICS; NCT02066129) clinical trial. The upper airway mycobiome was investigated using ITS1 sequencing of nasal blow samples collected from children with asthma when asthma was well controlled (baseline, n=194) and during early signs of loss of asthma control (yellow zone (YZ), n=107).
At baseline, 499 fungal genera were detected in the upper-airway samples, with two commensal fungal species Malassezia globosa and Malassezia restricta being most dominant. The relative abundance of Malassezia species vary by age, BMI, and race. Higher relative abundance of Malassezia globosa at baseline were associated with lower risk of future YZ episodes (p=0.038), and longer time to develop first episode of YZ (p=0.022). Higher relative abundance of Malassezia globosa at YZ was associated with lower risk of progression from YZ to severe asthma exacerbation (p=0.04). The upper airway mycobiome underwent significant changes from baseline to YZ, and increased fungal diversity was highly correlated with increased bacterial diversity (rho=0.41).
The upper airway commensal mycobiome is associated with future asthma control. This work highlights the importance of the mycobiota in asthma control and may contribute to the development of fungi-based markers to predict asthma exacerbation.

Copyright © 2023. Published by Elsevier Inc.