Alpha-hemolysin (Hla), the virulence factor secreted by Staphylococcus aureus (S. aureus), plays a critical role in infection and inflammation, which is a severe health burden worldwide. Therefore, it is necessary to develop a drug against Hla. Epigallocatechin gallate (EGCG), a polyphenol extracted from green tea, has excellent anti-inflammatory activity. In this study, we investigated the inhibitory effect of EGCG on Hla-induced NLRP3 inflammasome activation in vitro and in vivo and elucidated the potential molecular mechanism. We found that EGCG attenuated the hemolysis of Hla by inhibiting its secretion. Besides, EGCG significantly decreased overproduction of ROS and activation of MAPK signaling pathway induced by Hla, thereby markedly attenuating the expression of NLRP3 inflammasome-related proteins in THP-1 cells. Notably, EGCG could spontaneously bind to Hla with affinity constant of 1.71 × 10^-4 M, thus blocking the formation of the Hla heptamer. Moreover, Hla-induced expression of NLRP3, ASC and caspase-1 protein and generation of IL-1β and IL-18 in the damaged liver tissue of mice were also significantly suppressed by EGCG in a dose-dependent manner. Collectively, EGCG could be a promising candidate for alleviating Hla-induced the activation of NLRP3 inflammasome, depending on ROS mediated MAPK signaling pathway, and inhibition of Hla secretion and heptamer formation. These findings will enlighten the applications of EGCG to reduce the S. aureus infection by targeting Hla in food and related pharmaceutical fields.

α-溶血素 (Hla) 是金黄色葡萄球菌( S. aureus ) 分泌的毒力因子，在感染和炎症中起关键作用，这是全球范围内严重的健康负担。因此，有必要开发一种针对Hla的药物。表没食子儿茶素没食子酸酯 (EGCG) 是一种从绿茶中提取的多酚，具有优异的抗炎活性。在这项研究中，我们研究了 EGCG在体外和体内对 Hla 诱导的 NLRP3 炎性体活化的抑制作用。并阐明了潜在的分子机制。我们发现 EGCG 通过抑制 Hla 的分泌来减弱 Hla 的溶血作用。此外，EGCG显着降低了Hla诱导的ROS过度产生和MAPK信号通路的激活，从而显着减弱了THP-1细胞中NLRP3炎症小体相关蛋白的表达。值得注意的是，EGCG 可以自发地与 Hla 结合，亲和常数为 1.71 × 10 ^-4M，从而阻止 Hla 七聚体的形成。此外，EGCG也以剂量依赖性方式显着抑制Hla诱导的小鼠受损肝组织中NLRP3、ASC和caspase-1蛋白的表达以及IL-1β和IL-18的产生。总的来说，EGCG 可能是缓解 Hla 诱导的 NLRP3 炎症小体激活的有希望的候选药物，这取决于 ROS 介导的 MAPK 信号通路，以及 Hla 分泌和七聚体形成的抑制。这些发现将启发 EGCG在食品和相关制药领域通过靶向 Hla来减少金黄色葡萄球菌感染的应用。