Effect of Lactiplantibacillus plantarum cell-free culture on bacterial pathogens isolated from cystic fibrosis patients: in vitro and in vivo studies

This study aimed to investigate the effects of the cell-free supernatant of <i>Lactiplantibacillus plantarum</i> ATCC^® 10241^TM on the biofilm-forming capacity of <i>Pseudomonas aeruginosa</i> strains isolated from cystic fibrosis (CF) patients. In addition, the study evaluated the <i>in vivo</i> potential of the cell-free supernatant to modulate inflammation and reduce lung damage in mice infected with <i>P. aeruginosa</i> strains or co-challenged with <i>P. aeruginosa</i> and the <i>Streptococcus milleri</i> group (SMG). The results showed that CF-derived <i>P. aeruginosa</i> strains can infect the respiratory tract of adult mice, inducing local inflammation and lung damage. The severity of these infections was exacerbated when <i>P. aeruginosa</i> was co-administered with SMG. Notably, nebulization with the cell-free supernatant of <i>L. plantarum</i> produced beneficial effects, reducing respiratory infection severity and inflammatory responses induced by <i>P. aeruginosa</i>, both alone or in combination with SMG. Reduced bacterial loads and lung damage were observed in supernatant-treated mice compared to controls. Although further mechanistic studies are necessary, the results show that the cell-free supernatant of <i>L. plantarum</i> ATCC^® 10241^TM is an interesting adjuvant alternative to treat <i>P. aeruginosa</i> respiratory infections and superinfections in CF patients.