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Co-occurring bronchoalveolar lavage fluid microbiota and inflammatory features across BSI-defined disease severity groups during acute exacerbations of non-cystic fibrosis bronchiectasis

Year: 2026

Type: article

Abstract: Airway dysbiosis and inflammation characterize bronchiectasis, but their relationship with underlying disease severity during acute exacerbations remains unclear. We analyzed 135 adults hospitalized with acute exacerbations of non-cystic fibrosis bronchiectasis from a prospective single-center cohort. Bronchoalveolar lavage fluid (BALF) underwent shotgun metagenomic sequencing and inflammatory profiling. Participants were stratified by the Bronchiectasis Severity Index (BSI) as mild ( n = 27), moderate ( n = 37), or severe ( n = 71). Covariate-adjusted sensitivity analyses showed higher genus-level Pseudomonas and species-level Pseudomonas aeruginosa abundances in the severe group than in the mild and moderate groups (pairwise P adjusted ≤ 0.029) and lower Shannon diversity and Pielou evenness in the moderate and severe groups than in the mild group at both taxonomic levels (pairwise P adjusted ≤ 0.002), without moderate–severe differences in diversity. Community-level differences were modest (adjusted PERMANOVA marginal R ² = 0.021–0.024, P ≤ 0.020), and PERMDISP detected no significant dispersion differences. BALF inflammatory measures also varied across groups: IL-6 and IL-8 were higher in the moderate and severe groups than in the mild group ( P adjusted ≤ 0.020), and the neutrophil proportion was higher in the severe group than in the mild group ( P adjusted = 0.038). An exploratory inverse association was observed between species-level Pielou evenness and reported disease duration after multiplicity correction ( ρ = −0.320, P adjusted = 0.036). During acute exacerbations, BSI-defined bronchiectasis severity was associated with greater representation of Pseudomonas , particularly P. aeruginosa , within the BALF microbiota, reduced diversity and evenness, and differences in measured BALF cytokine concentrations and cellular composition. These co-occurring microbial and inflammatory features in BALF warrant longitudinal evaluation across clinical states to define their temporal dynamics and clinical relevance.

Source: Scientific Reports

DOI: 10.1038/s41598-026-69801-y