Characterizing Airway Microbiomes and Inflammatory Responses in Bronchiectasis Patients

The human microbiomes, including the respiratory tract, are described and characterized in an increasing number of studies. However, the composition and the impact of the healthy and/or impaired microbiome on pulmonary health and its interaction with the host tissues remain enigmatic. In chronic airway diseases, bronchiectasis stands out as a progressive condition characterized by microbial colonization and infection. In this study, we aimed to investigate the microbiome of the lower airways and lungs of bronchiectasis patients together with their serum cytokine and chemokine content, and gain novel insights into the pathogenesis of bronchiectasis. The microbiome of 47 patients was analyzed by sequencing of full-length 16S rRNA gene using amplicon sequencing Oxford Nanopore technologies. Their serum inflammatory mediators content was quantified in parallel. Several different types of microbiome composition groups were identified and characterized, the majority of patients displaying one dominant bacterial species, while others had a more diverse microbiota. The analysis of systemic immune responses revealed three distinct response groups, consisting of low, high, and dysregulated response groups, each associated with a specific array of clinical symptoms, microbial composition, and diversity. Moreover, some microbiome compositions were associated with high inflammatory response, i.e., high levels of pro- and anti-inflammatory cytokines, while others correlated with low inflammatory responses. Although, bronchiectasis pathogenetic mechanisms remain to be elucidated but it is clear that addressing microbiome composition in the airways is a valuable resource not only for diagnosis but also for personalized disease management.