Background: Bronchiectasis (BE) is an obstructive lung disease characterized by chronic cough and sputum production, recurrent bacterial infections and progressive lung damage.  Considering that dysregulated immune responses represent a key pathogenetic mechanism in both BE and chronic obstructive pulmonary disease (COPD), the identification of the precise immunological features that characterize each disease entity will allow better patient stratification and facilitate the development of more targeted, personalized therapies. Also neutrophils play a crucial role in host defense responses, reprogramming their pro-inflammatory functions towards more effective anti-pathogen protective immunity represents an attractive therapeutic approach for the management of BE and COPD. Our aim was to comprehensively characterize the immunophenotype of circulating neutrophils in patients with BE and COPD and explore correlations with clinical and immunological disease parameters.

Subjects and Methods: We obtained peripheral blood from BE, COPD and Healthy controls (HC) (n=10 ± 3). Characterization of the immunophenotype of circulating neutrophils were investigated by single-cell cytometry by time-of-flight (CyTOF). Circulating neutrophils were also analyzed for phagocytosis and NETosis assays by flow cytometry.

Results: CyTOF analysis revealed distinct populations between HC, COPD and BE. Also, phagocytosis was decreased in circulating neutrophils of BE patients compared to individuals with COPD and HC.

Conclusion: Our studies reveal dysregulated neutrophil responses in BE compared to COPD and HC.