The links between microbial environmental exposures and asthma are well documented, but no study has combined deep-sequencing results from pulmonary and indoor microbiomes of asthmatic patients with spirometry, clinical and endotype parameters.
The goal of this study was to investigate the links between indoor microbial exposures and pulmonary microbial communities and to document the role of microbial exposures on inflammatory and clinical outcomes of patients with severe asthma (SA).
Fifty-five SA patients from the national COBRA cohort were enrolled for analyzing their indoor microbial flora through the use of electrostatic dust collectors (EDCs). Among these patients, 22 were able to produce sputa during stable or pulmonary exacerbation periods and had complete pairs of EDC and sputum samples, both collected and analysed. We used amplicon targeted metagenomics to compare microbial communities from EDC and sputum samples of patients according to type 2 (T2)-asthma endotypes.
Compared to patients with T2-low SA, patients with T2-high SA exhibited an increase in bacterial alpha-diversity and a decrease in fungal alpha-diversity of their indoor microbial floras, the latter being significantly correlated with FeNO levels. The beta-diversity of the EDC mycobiome significantly clustered according to T2 endotypes. Moreover, the proportion of fungal taxa in common between sputum and EDC samples was significantly higher when patients exhibited acute exacerbation.
These results illustrated, for the first time, a potential association between the indoor mycobiome and clinical features of SA patients, which should renew interest in deciphering the interactions between indoor environment, fungi, and host in asthma.

Copyright © 2020. Published by Elsevier Inc.