Several experimental evidences support the oral administration of probiotics in CF patients, although this measure still requires full demonstration of its clinical efficacy. In our project, we hypothesized that the administration of selected probiotic strains via aerosol could exert a local beneficial effect, directly at the site of lung infections, increasing the effectiveness of probiotics in CF, as a replacement or complementary measure to the use of antibiotics. Strains of probiotics belonging to the Lactobacillus genus and approved for human use, have been evaluated in in vitro models for their ability to: i) survive in experimental conditions mimicking CF lung; ii) counteract the growth of pathogenic bacteria isolated from CF lung and limit their virulence; iii) adhere and inhibit the adhesion of P. aeruginosa to human lung epithelial cells; iv) exert an anti-inflammatory effect on peripheral blood cells which are the main mediators of inflammation and decline of pulmonary functions in CF. The screening showed that L. rhamnosus and L. plantarum are promising candidates to survive in the CF lung environment and to compete with P. aeruginosa strains in both planktonic and biofilm mode of growth. L. plantarum, in particular, has shown an interesting ability to interfere with the presence of the thick matrix that protects P. aeruginosa in the biofilm, enhancing the activity of the antibiotic tobramycin against the bacterium. L. acidophilus showed the greatest adhesive properties to lung epithelial cells and the ability to reduce the adhesion of P. aeruginosa to the same cells. L. acidophilus also reduced the release of pro-inflammatory cytokines by P. aeruginosa-stimulated peripheral blood cells, suggesting an anti-inflammatory potential of such strain. Overall, the project identified L. plantarum, L. rhamnosus and L. acidophilus as interesting candidates for an aerosol administration in CF. Future studies in relevant in vitro and animal models will help to lay rational foundations for their future use in the clinic.

Abstract presentati a congressi scientifici

• Activity of cell-free supernatants from probiotic Lactobacillus strains against Pseudomonas aeruginosa from cystic fibrosis patients. 50° Congresso Nazionale della Società Italiana di Microbiologia, Napoli 18-21 settembre 2022.
• Antibacterial and antibiofilm activity in artificial sputum medium of Lactobacilli against Pseudomonas aeruginosa strains isolated from cystic fibrosis patients. 50° Congresso Nazionale della Società Italiana di Microbiologia, Napoli 18-21 settembre 2022.
• In vitro anti-bacterial, anti-biofilm, and anti-adhesive effects of Lactobacillus strains on Pseudomonas aeruginosa isolated from cystic fibrosis patients. EuroBiofilms 2022, Mallorca, Spain, 31st August to 3rd September 2022.
• Three-label host-cell adhesion assay to assess the exclusion effect exerted by Lactobacillus acidophilus on adhesion of Pseudomonas aeruginosa to A549 alveolar epithelial cells. 50° Congresso Nazionale della Società Italiana di Microbiologia, Napoli 18-21 settembre 2022.