Baicalin inhibits biofilm formation, attenuates the quorum sensing-controlled virulence and enhances Pseudomonas aeruginosa clearance in a mouse peritoneal implant infection model
Baicalin inhibits biofilm formation, attenuates the quorum sensing-controlled virulence and enhances Pseudomonas aeruginosa clearance in a mouse peritoneal implant infection model
复制标题
黄芩苷在小鼠腹膜植入物感染模型中抑制生物膜形成，减弱群体感应控制的毒力并增强铜绿假单胞菌清除率
DOI：
10.1371/journal.pone.0176883
复制
发表时间：
2017-04-28
期刊：
影响因子：
3.7
通讯作者：
Chen, Yiqiang
中科院分区：
文献类型：
--
作者：
Luo, Jing;Dong, Biying;Chen, Yiqiang
群体感应（QS）电路在控制铜绿假单胞菌毒力因子和生物膜形成的基因的精确调节中发挥作用。由于新出现的耐药性，铜绿假单胞菌在临床环境中 QS 控制的生物膜形成仍然存在争议。因此，筛选不同化合物的抗生物膜或抗 QS 活性非常重要。本研究证明了黄芩苷（一种从传统中药黄芩中提取的活性天然化合物）在亚最低抑菌浓度（亚MIC）下能够抑制铜绿假单胞菌生物膜的形成，并增强各种常规抗生素的体外杀菌效果。此外，黄芩苷对铜绿假单胞菌中由QS调节的毒力表型（LasA蛋白酶、LasB弹性蛋白酶、绿脓素、鼠李糖脂、运动力和外毒素A）具有剂量依赖性抑制作用。此外，亚MIC黄芩苷处理后，QS调节基因（包括lasI、lasR、rhlI、rhlR、pqsR和pqsA）的表达水平受到抑制，导致QS信号分子3-oxo-C12-HSL和C4-HSL显着降低，证实了黄芩苷介导的QS抑制改变基因和蛋白质表达的能力。体内实验表明，黄芩苷治疗可降低绿脓杆菌对秀丽隐杆线虫的致病性。黄芩苷处理组的蠕虫存活率更高，表现为 LT50 从 24 小时增加到 96 小时。在小鼠腹膜植入物感染模型中，与对照组相比，黄芩苷治疗增强了感染铜绿假单胞菌的小鼠植入物中铜绿假单胞菌的清除率。此外，黄芩苷和抗生素的组合显着减少了植入物中集落形成单位的数量，其程度显着高于单独的抗生素治疗。病理和组织学分析表明，黄芩苷治疗后，炎症反应减轻，植入物周围腹膜组织的细胞浸润减少。对黄芩苷治疗组小鼠腹腔灌洗液中细胞因子水平的测量显示，与对照组相比，IL-4降低，干扰素γ（IFN-γ）增加，并且IFN-γ/IL-4比率逆转，表明黄芩苷治疗激活了Th1诱导的免疫反应，加速细菌负荷清除。基于这些结果，黄芩苷可能是一种有效的 QS 抑制剂和抗生物膜剂，用于对抗铜绿假单胞菌生物膜相关感染。
The quorum sensing (QS) circuit plays a role in the precise regulation of genes controlling virulence factors and biofilm formation in Pseudomonas aeruginosa. QS-controlled biofilm formation by Pseudomonas aeruginosa in clinical settings has remained controversial due to emerging drug resistance; therefore, screening diverse compounds for anti-biofilm or anti-QS activities is important. This study demonstrates the ability of sub-minimum inhibitory concentrations (sub-MICs) of baicalin, an active natural compound extracted from the traditional Chinese medicinal Scutellaria baicalensis, to inhibit the formation of Pseudomonas aeruginosa biofilms and enhance the bactericidal effects of various conventional antibiotics in vitro. In addition, baicalin exerted dose-dependent inhibitory effects on virulence phenotypes (LasA protease, LasB elastase, pyocyanin, rhamnolipid, motilities and exotoxin A) regulated by QS in Pseudomonas aeruginosa. Moreover, the expression levels of QS-regulatory genes, including lasI, lasR, rhlI, rhlR, pqsR and pqsA, were repressed after sub-MIC baicalin treatment, resulting in significant decreases in the QS signaling molecules 3-oxo-C12-HSL and C4-HSL, confirming the ability of baicalin-mediated QS inhibition to alter gene and protein expression. In vivo experiments indicated that baicalin treatment reduces Pseudomonas aeruginosa pathogenicity in Caenorhabditis elegans. Greater worm survival in the baicalin-treated group manifested as an increase in the LT50 from 24 to 96 h. In a mouse peritoneal implant infection model, baicalin treatment enhanced the clearance of Pseudomonas aeruginosa from the implants of mice infected with Pseudomonas aeruginosa compared with the control group. Moreover, the combination of baicalin and antibiotics significantly reduced the numbers of colony-forming units in the implants to a significantly greater degree than antibiotic treatment alone. Pathological and histological analyses revealed mitigation of the inflammatory response and reduced cell infiltration in the peritoneal tissue surrounding the implants after baicalin treatment. Measurement of the cytokine levels in the peritoneal lavage fluid of mice in the baicalin treatment group revealed a decrease in IL-4, an increase in interferon γ (IFN-γ), and a reversed IFN-γ/IL-4 ratio compared with the control group, indicating that baicalin treatment activated the Th1-induced immune response to expedite bacterial load clearance. Based on these results, baicalin might be a potent QS inhibitor and anti-biofilm agent for combating Pseudomonas aeruginosa biofilm-related infections.