Yu Hangqian, Liu Jingyu, Wang Li, Guan Shuhan, Jin Yajing, Zheng Jianze, Xiang Hua, Wang Dacheng, Liu Dianfeng
College of Animal Science, Jilin University, Changchun, China.
Changchun University of Chinese Medicine, Changchun, China.
Front Microbiol. 2022 Aug 23;13:969215. doi: 10.3389/fmicb.2022.969215. eCollection 2022.
Due to powerful drug resistance and fatal toxicity of methicillin-resistant (MRSA), therapeutic strategies against virulence factors present obvious advantages since no evolutionary pressure will induce bacterial resistance. Alpha-hemolysin (Hla) is an extracellular toxin secreted by and contributes to bacterial pathogenicity. Herein, we identified a natural product 2,3-dehydrokievitone (2,3-DHKV) for inhibiting Hla activity of MRSA strain USA300 but not affecting bacteria growth. 2,3-DHKV significantly decreased hemolysin expression in a dose-dependent manner, but it did not potently neutralize hemolysin activity. Subsequently, cellular thermal shift and heptamer formation assays confirmed that 2,3-DHK affects hemolytic activity through indirect binding to Hla. RT-qPCR and western blot revealed that 2,3-DHKV suppressed Hla expression at the mRNA and protein levels, and further decreased accessory gene regulator A () transcription levels. We also observed that 2,3-DHK significantly attenuated the damage of A549 cells by and reduced the release of lactate dehydrogenase (LDH). Moreover, in the MRSA-induced pneumonia mouse model, 2,3-DHK treatment prolonged the life span of mice and reduced the bacterial load in the lungs, which significantly alleviated the damage to the lungs. In summary, this study proved that 2,3-DHK as a Hla inhibitor is a potential antivirulence agent against MRSA infection.
由于耐甲氧西林金黄色葡萄球菌（MRSA）具有强大的耐药性和致命毒性，针对毒力因子的治疗策略具有明显优势，因为不会有进化压力诱导细菌产生耐药性。α-溶血素（Hla）是由MRSA分泌的一种细胞外毒素，对细菌致病性有作用。在此，我们鉴定出一种天然产物2,3-脱氢基维酮（2,3-DHKV），它可抑制MRSA菌株USA300的Hla活性，但不影响细菌生长。2,3-DHKV以剂量依赖的方式显著降低溶血素表达，但它不能有效中和溶血素活性。随后，细胞热迁移和七聚体形成试验证实2,3-DHK通过间接结合Hla来影响溶血活性。RT-qPCR和蛋白质印迹显示2,3-DHKV在mRNA和蛋白质水平上抑制Hla表达，并进一步降低辅助基因调节因子A（）的转录水平。我们还观察到2,3-DHK显著减轻了USA300对A549细胞的损伤，并减少了乳酸脱氢酶（LDH）的释放。此外，在MRSA诱导的肺炎小鼠模型中，2,3-DHK治疗延长了小鼠的寿命，降低了肺部的细菌载量，显著减轻了对肺部的损伤。总之，本研究证明2,3-DHK作为一种Hla抑制剂是一种潜在的抗MRSA感染的抗毒力剂。
