Xu Gan-Fei, Wang Jing-Jing, Wu Da-Qiang, Guan Yan
School of Life Sciences, Anhui University, Hefei 230601, China.
College of Traditional Chinese Medicine and Western Medicine, Anhui University of Chinese Medicine, Hefei 230038, China.
Zhongguo Zhong Yao Za Zhi. 2017 Jun;42(11):2131-2138. doi: 10.19540/j.cnki.cjcmm.2017.0094.
Quorum sensing of bacteria and its specific gene expression regulation have a very important role in bacterial biofilm formation. LuxS and agr are the key regulatory genes in quorum sensing of Staphylococcus epidermidis, and RNA Ⅲ is the effector molecule of agr system. In order to evaluate the effects of sodium houttuyfonate in combination with erythromycin on the transcription level of S. epidermidis, serial dilution method was used to determine the MIC of sodium houttuyfonate, erythromycin and vancomycin on S. epidermidis, and fluorescent quantitative PCR method was used to detect the transcription levels of luxS, agr/RNAⅢ in different time periods after treatment on S. epidermidis by sodium houttuyfonate in combination with erythromycin, vancomycin, and erythromycin alone. Our results showed that in treatment by 1/2MIC, 1/4MIC sodium houttuyfonate, 1/2MIC sodium houttuyfonate +1/2MIC erythromycin, 1/4MIC sodium houttuyfonate+1/4MIC erythromycin, and 1/8MIC sodium houttuyfonate+1/8MIC erythromycin for ATCC 35984, they could rapidly up-regulate the expression of luxS of S. epidermidis from the beginning as compared with negative control, with significant differences (P<0.05); furthermore, sodium houttuyfonate can still up-regulate the expression of luxS even after treatment for 6, 12 and 48 h. Sodium houttuyfonate in MIC and 1/2MIC concentration can significantly down-regulate the expression of agr (P<0.05); 1/2MIC sodium houttuyfonate+1/2MIC erythromycin, 1/4MIC sodium houttuyfonate+1/4MIC erythromycin, can also significantly down-regulate the expression of agr in 6 h, 12 h and 24 h(P<0.05). Sodium houttuyfonate in MIC, can significantly down-regulate the expression of RNA Ⅲ (P<0.05), and 1/2MIC sodium houttuyfonate+1/2MIC erythromycin can also significantly down-regulate the expression of RNAⅢ(P<0.05). Therefore, our presented results showed that sodium houttuyfonate in combination with erythromycin can rapidly up-regulate the transcription of luxS of S. epidermidis, and can down-regulate the expression of agr/RNA Ⅲ in certain concentrations, and suggested that sodium houttuyfonate in combination of erythromycin could inhibit mutual aggregation between S. epidermidis and biofilm bacteria, inhibit membrane nutrition and formation of water transport channels, prevent separation of bacterial cells in biofilm, and inhibit the formation of bacterial exotoxin of S. epidermidis.
细菌群体感应及其特定基因表达调控在细菌生物膜形成中具有非常重要的作用。LuxS和agr是表皮葡萄球菌群体感应中的关键调控基因，RNAⅢ是agr系统的效应分子。为了评估鱼腥草素钠联合红霉素对表皮葡萄球菌转录水平的影响，采用系列稀释法测定鱼腥草素钠、红霉素和万古霉素对表皮葡萄球菌的最低抑菌浓度（MIC），并采用荧光定量PCR法检测鱼腥草素钠联合红霉素、万古霉素及单独使用红霉素处理表皮葡萄球菌后不同时间段luxS、agr/RNAⅢ的转录水平。我们的结果显示，对于ATCC 35984，用1/2MIC、1/4MIC鱼腥草素钠，1/2MIC鱼腥草素钠 + 1/2MIC红霉素，1/4MIC鱼腥草素钠 + 1/4MIC红霉素，以及1/8MIC鱼腥草素钠 + 1/8MIC红霉素处理后，与阴性对照相比，它们从一开始就能迅速上调表皮葡萄球菌luxS的表达，差异有统计学意义（P<0.05）；此外，即使处理6、12和48小时后，鱼腥草素钠仍能上调luxS的表达。MIC和1/2MIC浓度的鱼腥草素钠能显著下调agr的表达（P<0.05）；1/2MIC鱼腥草素钠 + 1/2MIC红霉素、1/4MIC鱼腥草素钠 + 1/4MIC红霉素在6小时、12小时和24小时也能显著下调agr的表达（P<0.05）。MIC浓度的鱼腥草素钠能显著下调RNAⅢ的表达（P<0.05），1/2MIC鱼腥草素钠 + 1/2MIC红霉素也能显著下调RNAⅢ的表达（P<0.05）。因此，我们的研究结果表明，鱼腥草素钠联合红霉素能迅速上调表皮葡萄球菌luxS的转录，并能在一定浓度下下调agr/RNAⅢ的表达，提示鱼腥草素钠联合红霉素可抑制表皮葡萄球菌与生物膜细菌之间的相互聚集，抑制膜营养和水转运通道的形成，防止生物膜中细菌细胞的分离，并抑制表皮葡萄球菌细菌外毒素的形成。
