Department of Thoracic Surgery, the First Hospital of Jilin University, Changchun, Jilin, China.
Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, Jilin, China.
J Appl Microbiol. 2021 Mar;130(3):843-851. doi: 10.1111/jam.14769. Epub 2020 Sep 20.
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.
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.
Betulin could be used as a promising leading compound against S. pneumoniae virulence by directly targeting PLY without antibacterial activity.
The results presented in this work provided a novel strategy and candidate for S. pneumoniae infection.
肺炎链球菌溶血素（Pneumolysin）是一种重要的毒力因子，具有多种生物学活性，如细胞溶解和 DNA 损伤。因此，针对这种毒素是治疗肺炎链球菌感染的一种替代策略。
通过溶血试验鉴定潜在的 PLY 抑制剂。通过 MICs 测定、Western blot 分析和寡聚化分析确定桦木醇（一种来自桦树皮的天然化合物）对抗 PLY 的作用机制。进一步通过细胞毒性和免疫荧光试验评估桦木醇对 PLY 诱导的细胞损伤和 DNA 损伤的保护作用。在此，桦木醇作为一种来自桦树皮的天然化合物，被鉴定为 PLY 的有效抑制剂。重要的是，在抑制所需的浓度下，桦木醇对肺炎链球菌的活力或 PLY 的产生没有影响。桦木醇与 PLY 的相互作用限制了该毒素的寡聚化，从而直接中和 PLY 的活性。此外，桦木醇处理可减轻 PLY 和 A549 细胞共培养系统中 PLY 诱导的细胞损伤和 DNA 损伤。
桦木醇可通过直接靶向 PLY 而不具有抗菌活性，作为一种有前途的针对肺炎链球菌毒力的先导化合物。
本工作的结果为肺炎链球菌感染提供了一种新的策略和候选药物。
