背景:变形链球菌已被认为是龋齿的主要病原体,其重要的毒力特性之一是在牙齿表面形成生物膜的能力。因此,需要预防和控制变形链球菌生物膜的策略。本研究旨在使用源自乳杆菌物种的后生物介质增强的核黄素(Rib)介导的抗微生物光动力疗法(aPDT)来检查对变形链球菌浮游和生物膜细胞的根除。
方法:测定Rib和后生物介质的最低抑菌浓度(MIC)和最低杀菌浓度(MBC)。Rib介导的aPDT(Rib加蓝光)的抗菌和抗生物膜作用,肋骨介导的aPDT与源自干酪乳杆菌(LC)(aPDTLC)的后生物介质组合,评估了Rib介导的aPDT与源自植物乳杆菌(LP)(aPDTLP)的后生物介质的组合。Rib介导的aPDT的抗毒力潜力,aPDT+LC,通过在最高浓度的Rib下使用定量实时聚合酶链反应(qRT-PCR)测量gtfB基因的表达来评估aPDTLP,LC,LP,变异链球菌的增殖与对照组(未处理)相同。
结果:根据结果,LC的MIC剂量,LP,肋骨为64微克/毫升,128微克/毫升,和128微克/毫升,分别,而LC的MBC值,LP,肋骨为128微克/毫升,256微克/毫升,和256微克/毫升,分别。肋骨介导的aPDT,aPDT+LP,与对照组相比,aPDT+LC显示Log10CFU/mL的变形链球菌显着降低(4.2、4.9和5.2Log10CFU/mL,分别;所有P<0.05)。用aPDT+LC处理后观察到变形链球菌生物膜的破坏最多,其次是aPDT+LP和Rib介导的aPDT(77.5%,73.3%,和67.6%,分别;所有P<0.05)。浓度为31.2微克/毫升,62.5µg/mL,和62.5μg/mL被认为是最高浓度的LC,LP,和肋骨,分别,其中变异链球菌与对照组一样复制,并在Rib介导的aPDT期间使用qRT-PCR用于gtfB基因表达测定,aPDT+LP,和aPDT+LC治疗。基因表达结果显示,aPDT+LP和aPDT+LC可以使gtfB的基因表达水平降低6.3倍和5.7倍,分别为(P<0.05),而Rib介导的aPDT仅减少5.1倍(P<0.05)。
结论:我们的研究结果表明,aPDT+LP和aPDT+LC有望用作对抗变形链球菌浮游和生物膜生长的治疗方法,以及作为通过减少gtfB基因表达来抑制生物膜发育的预防策略的抗毒力。
BACKGROUND: Streptococcus mutans has been implicated as a primary causative agent of dental caries and one of its important virulence properties is an ability to form biofilm on tooth surfaces. Thus, strategies to prevent and control S. mutans biofilms are requested. The present study aimed to examine the eradication of S. mutans planktonic and biofilm cells using riboflavin (Rib)-mediated antimicrobial photodynamic therapy (aPDT) enhanced by postbiotic mediators derived from Lactobacillus species.
METHODS: Minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of Rib and postbiotic mediators were determined. The antimicrobial and anti-biofilm effects of Rib-mediated aPDT (Rib plus blue light), Rib-mediated aPDT in combination with postbiotic mediators derived from Lactobacillus casei (LC) (aPDT+ LC), and Rib-mediated aPDT in combination with postbiotic mediators derived from Lactobacillus plantarum (LP) (aPDT+ LP) were evaluated. The anti-virulence potential of Rib-mediated aPDT, aPDT+ LC, and aPDT+ LP were assessed by measuring the expression of the gtfB gene using quantitative real-time polymerase chain reaction (qRT-PCR) at the highest concentrations of Rib, LC, and LP, at which the S. mutans had proliferation as the same as in the control (non-treated) group.
RESULTS: According to the results, the MIC doses of LC, LP, and Rib were 64 µg/mL, 128 µg/mL, and 128 µg/mL, respectively, while the MBC values of LC, LP, and Rib were 128 µg/mL, 256 µg/mL, and 256 µg/mL, respectively. Rib-mediated aPDT, aPDT+ LP, and aPDT+ LC showed a significant reduction in Log10 CFU/mL of S. mutans compared to the control group (4.2, 4.9, and 5.2 Log10 CFU/mL, respectively; all P < 0.05). The most destruction of S. mutans biofilms was observed after treatment with aPDT+ LC followed by aPDT+ LP and Rib-mediated aPDT (77.5%, 73.3%, and 67.6%, respectively; all P < 0.05). The concentrations of 31.2 µg/mL, 62.5 µg/mL, and 62.5 µg/mL were considered as the highest concentrations of LC, LP, and Rib, respectively, at which S. mutans replicates as same as the control group and were used for gtfB gene expression assay using qRT-PCR during Rib-mediated aPDT, aPDT+ LP, and aPDT+ LC treatments. Gene expression results revealed that aPDT+ LP and aPDT+ LC could decrease the gene expression level of gtfB by 6.3- and 5.7-fold, respectively (P < 0.05), while only 5.1-fold reduction was observed after Rib-mediated aPDT (P < 0.05).
CONCLUSIONS: Our findings indicate that aPDT+ LP and aPDT+ LC hold promise for use as a treatment to combat S. mutans planktonic and biofilms growth as well as anti-virulence as a preventive strategy to inhibit biofilms development via reduction of gtfB gene expression.