Betulin attenuates pneumolysin-induced cell injury and DNA damage.

AIMS

Pneumolysin, a pore-forming toxin, is an important virulence factor of Streptococcus pneumoniae with multiple biological activity, such as cell lysis and DNA damage. Thus, targeting this toxin is alternative strategy for the treatment of S. pneumoniae infection.

METHODS AND RESULTS

Haemolysin assay was performed to identify the potential PLY inhibitor. The mechanism by which betulin, a natural compound from birch bark, against PLY was determined via MICs determination, western blot analysis and oligomerization analysis. Cytotoxicity and Immunofluorescence assays were further used to evaluate the protection of betulin against PLY-induced cell injury and DNA damage. Here, betulin, a natural compound from birch bark, was indentified as an effective inhibitor of PLY. Importantly, at the concentrations required for such inhibition, betulin has no influence on S. pneumoniae viability or PLY production. The interaction of betulin with PLY restrict the olgomerizaiton of this toxin and, thus, directly neutralizing the activity of PLY. Additionally, betulin treatment alleviate PLY induced cells injury and DNA damage in the co-culture system of PLY and A549 cells.

CONCLUSIONS

Betulin could be used as a promising leading compound against S. pneumoniae virulence by directly targeting PLY without antibacterial activity.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results presented in this work provided a novel strategy and candidate for S. pneumoniae infection.