Inhaled Lacticaseibacillus rhamnosus-derived postbiotics as novel strategy to tackle Pseudomonas aeruginosa lung infection in cystic fibrosis
Bianchi M.1, Grassiri B.2, Esin S.1, Kaya E.1, Maisetta G.1, Piras AM.2 & Batoni G.1
1Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Via S. Zeno 35-39, Pisa, 56123, Italy
2Department of Pharmacy, University of Pisa, Via Bonanno 33, Pisa, 56126, Italy
Summary
Probiotics or their metabolic products, also referred to as postbiotics, have recently gained interest as potential antimicrobials, given the rise of multidrug-resistant pathogens and the loss of efficacy of many antibiotics in the clinic. This study aimed to investigate the antimicrobial activity of cell-free supernatants from Lacticaseibacillus rhamnosus (CFS-LR) against Pseudomonas aeruginosa strains isolated from the sputum of cystic fibrosis (CF) patients. In addition, we aimed at developing a liquid CFS formulation for aerosol administration, in view of future implementation of CFS as inhaled therapy to treat or prevent P. aeruginosa lung-infections. When tested in an in-vitro P. aeruginosa lung infection model, CFS-LR exhibited a marked antibacterial effect reducing P. aeruginosa viable count of approximately 2 Logs within 7h of incubation at the dilution 1:8, while causing complete eradication of P. aeruginosa at the dilution of 1:4. Cytotoxicity assessment of CFS-LR against monolayers of NCI-H441 human distal lung epithelial cells demonstrated that the dilution of 1:8 was well tolerated, while marked levels of cell-death were observed at the 1:4 dilution. The aerodynamic distribution of nebulized CFS-LR was evaluated by a twin-stage impinger, using an Aerogen® mesh nebulizer. As much as 76% of the nebulized CFS-LR solution was deposited in the second stage of the model suggesting a satisfactory distribution in the profound airways. Though CFS-LR lyophilization caused partial reduction of the bactericidal potential, marked levels of antimicrobial activity were retained. In conclusion, these findings support the study of CFS aerosol delivery as an innovative strategy to control P. aeruginosa lung–infections.