Abstract
The mannose-rich exopolysaccharide EPS B3-15, produced by the thermophilic Bacillus licheniformis B3-15, was previously reported to possess promising potentialities as antiviral and immunomodulatory agent, and in preventing the adhesion of Pseudomonas aeruginosa and Staphylococcus aureus. In this study, EPS B3-15 was evaluated for its anti-inflammatory activity in LPS-induced macrophages and the ability to contrast the adhesion of Klebsiella pneumoniae and Streptococcus pneumoniae as pathogenic bacteria of the respiratory tract. Without affecting the macrophages viability, the EPS at low concentration (300 μg/mL) significantly downregulated the gene expression of iNOS and the consequent NO generation, and it also decreased the production of pro-inflammatory cytokines. Moreover, the EPS reduced the adhesion of Str. pneumoniae (47 %) more efficiently than K. pneumoniae (38 %), due to its ability to modify the abiotic surfaces properties and alter the charges of bacterial-cell surface of Gram-positive more than Gram-negative. As able to reduce the inflammatory responses in macrophage cells and simultaneously prevent biofilm-related to the respiratory tract infections, EPS B3-15 could have potential use as nasal spray with anti-inflammatory action and surface-coating agent for medical devices.