Pseudomonas aeruginosa virulence factors and immune response during exacerbations and stable phase in bronchiectasis.

<bold>Background:</bold> Pseudomonas aeruginosa (<italic>PA</italic>) virulence factors' impact on immune response in Non-Cystic Fibrosis Bronchiectasis (BE) during stable phase and exacerbations (PExs) remains unstudied. <bold>Aim:</bold> To compare the immune response of patients and <italic>PA</italic> virulence factors during stable phase and PExs in patients with BE colonized by <italic>PA</italic>. <bold>Methods:</bold> <italic>PA</italic> strain were prospectively collected from sputum and serum samples of 7 patient during both stable phase and subsequent PExs. <italic>PA</italic> counts were obtained and reported as logarithmic scale colony forming units per mL (LogCFU/mL). The number of <italic>PA</italic> strains secreting virulence factors (<italic>ExoS, ExoY, Pvds</italic>) was analyzed using RT-qPCR. Serum samples were assessed for immunoglobulin levels (mg/dl) and interleukin levels (pg/mL) using ELISA and Luminex technology. The non-parametric Wilcoxon signed-rank test for paired data was performed. <bold>Results:</bold> <italic>PA</italic> load did not differ between the stable phase and PExs (Fig A). <italic>ExoS</italic> production increased non-significantly during PExs (Fig B). Serum levels of IL-6, IL-7, IL-10, and IL-1, as well as IgG1 were higher during PExs compared to stable phase (Fig C and Fig D). <bold>Conclusion:</bold> Although <italic>PA</italic> load remained above 4LogCFU/mL in sputum from BE patients regardless of stable phase or PExs, inflammatory cytokine levels increased during PExs. Thus, our data emphasize the importance of targeting not only <italic>PA</italic> but also inflammation in BE PExs.