Abstract：
Pneumolysin (Ply) is an indispensable cholesterol-dependent cytolysin for pneumococcal infection. Although Ply-induced disruption of pneumococci-containing endosomal vesicles is a prerequisite for the evasion of endolysosomal bacterial clearance, its potent activity can be a double-edged sword, having a detrimental effect on bacterial survivability by inducing severe endosomal disruption, bactericidal autophagy, and scaffold epithelial cell death. Thus, Ply activity must be maintained at optimal levels. We develop a highly sensitive assay to monitor endosomal disruption using NanoBiT-Nanobody, which shows that the pneumococcal sialidase NanA can fine-tune Ply activity by trimming sialic acid from cell-membrane-bound glycans. In addition, oseltamivir, an influenza A virus sialidase inhibitor, promotes Ply-induced endosomal disruption and cytotoxicity by inhibiting NanA activity in vitro and greater tissue damage and bacterial clearance in vivo. Our findings provide a foundation for innovative therapeutic strategies for severe pneumococcal infections by exploiting the duality of Ply activity.
摘要：
肺炎球菌溶血素（Ply）是肺炎球菌感染必不可少的胆固醇依赖性细胞溶素。尽管Ply诱导的含肺炎球菌的内体囊泡破坏是逃避内溶酶体细菌清除的先决条件，它强大的活性可以是一把双刃剑，通过诱导严重的内体破坏对细菌生存能力产生有害影响，杀菌自噬，和支架上皮细胞死亡。因此，垫层活动必须保持在最佳水平。我们开发了一种使用NanoBiT-Nanobody监测内体破坏的高灵敏度测定法，这表明肺炎球菌唾液酸酶NanA可以通过从细胞膜结合的聚糖中修剪唾液酸来微调Ply活性。此外,奥司他韦,甲型流感病毒唾液酸酶抑制剂，通过抑制体外NanA活性和体内更大的组织损伤和细菌清除来促进Ply诱导的内体破坏和细胞毒性。我们的发现通过利用Ply活性的双重性，为严重肺炎球菌感染的创新治疗策略提供了基础。
