Associations between fungal and bacterial microbiota of airways and asthma endotypes.
J Allergy Clin Immunol. 2019 Jul 03;:
Authors: Sharma A, Laxman B, Naureckas ET, Hogarth DK, Sperling AI, Solway J, Ober C, Gilbert JA, White SR
BACKGROUND: The relationship between asthma, atopy and underlying type-2 (T2) airway inflammation is complex. While the bacterial airway microbiota is known to differ in asthmatic patients, the fungal and bacterial markers that discriminate T2-High (eosinophilic) and T2-Low (neutrophilic/mixed-inflammation) asthma and atopy are still incompletely identified.
OBJECTIVES: The aim of this study was to demonstrate the fungal microbiota structure of airways in asthmatic subjects associated with T2- inflammation, atopy and key clinical parameters.
METHODS: We collected endobronchial brush (EB) and bronchoalveolar lavage (BAL) samples from 39 asthmatic and 19 healthy subjects followed by 16S gene and ITS based microbiota sequencing. The microbial sequences were classified into Exact Sequence Variants (ESVs). The T2 phenotype was defined using a blood eosinophil count <> 300 cells/μl.
RESULTS: Fungal diversity was significantly lower in EB samples from T2-High compared to T2-Low patients; key fungal genera enriched in T2-High patients included Trichoderma, whereas Penicillium was enriched in subjects with atopy. In BAL samples the dominant genera were Cladosporium, Fusarium, Aspergillus, and Alternaria. Using generalized linear models, we identified significant associations between specific fungal ESVs and FEV1, FeNO, BAL cells, and corticosteroid usage. Investigation of interkingdom (bacterial-fungal) co-occurrence patterns revealed different topologies between asthmatic subjects and healthy controls. Random Forest models with fungal-classifiers predicted asthma status with 75% accuracy (BAL samples) and 80% accuracy (EB samples).
CONCLUSIONS: We demonstrate clear differences in the bacterial and fungal microbiota in asthma-associated phenotypes. Our study provides additional support for considering microbial signatures in delineating asthma phenotypes.
PMID: 31279011 [PubMed – as supplied by publisher]