Pourhajibagher Maryam, Parker Steven, Pourakbari Babak, Valian Nasrin Keshavarz, Raoofian Reza, Bahador Abbas
Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
Leicester School of Pharmacy, De Montfort University, Leicester LE1 9BH, United Kingdom.
Photodiagnosis Photodyn Ther. 2023 Mar;41:103308. doi: 10.1016/j.pdpdt.2023.103308. Epub 2023 Jan 25.
Streptococcus mutans is considered a major significant contributor to dental caries and its effective removal is difficult due to the formation of biofilm. Therefore, the development of adjuvant therapeutic strategies with anti-biofilm properties is a promising approach. In the present study, we examined the effect of dermcidin-derived peptide DCD-1 L on the antibacterial activity of hypericin nanoparticle (HypNP)-mediated antimicrobial sonodynamic therapy (aSDT) against persister cells growing- and biofilm cultures of S. mutans.
Following synthesis and confirmation of HypNP, the fractional inhibitory concentration (FIC) index of HypNP and DCD-1 L was determined by checkerboard assay. Cellular uptake of HypNP-DCD-1 L and generation of endogenous reactive oxygen species (ROS) were assessed and followed by the determination of antimicrobial sonoactivity of HypNP-DCD-1 L against persister cells growing- and biofilm cultures of S. mutans. The water-insoluble extracellular polysaccharide (EPS) and expression of the gtfD, comDE, and smuT genes were then evaluated in persister cells growing- and biofilm cultures of S. mutans.
There was a synergistic activity in the combination of HypNP and DCD-1 L against S. mutans with an FIC index value of 0.37. The HypNP-DCD-1L-mediated aSDT also displayed the highest cellular uptake and endogenous ROS generation by bacterial cells. When biofilm and persister cells of S. mutans were treated with HypNP-DCD-1 L and subsequently exposed to ultrasound waves, 5.1 log and 3.8 log reductions, respectively, in bacterial numbers were observed (P<0.05). According to the data, EPS in both persister cells growing- and biofilm cultures of S. mutans were significantly decreased after exposure to the HypNP-DCD-1L-mediated aSDT (P<0.05). In addition, the quantitative real-time PCR data illustrated the high level of similarities in very low-expression profiles of the gtfD before and after all treated groups for persister cells. While, following HypNP-DCD-1L-mediated aSDT treatment, the expression levels of gtfD, comDE, and smuT were significantly lower in treated persister cells growing- and biofilm cultures of S. mutans in comparison with control groups (P<0.05).
Combined, the results of this study indicate that ultrasound waves-activated HypNP-DCD-1 L can sonoinactivate S. mutans biofilms and persister cells, as well as reduce effectively pathogenicity potency of S. mutans. Hence, HypNP-DCD-1L-mediated aSDT may be proposed as a promising adjunctive therapeutic approach for dental caries.
变形链球菌被认为是导致龋齿的主要重要因素，由于生物膜的形成，有效清除它很困难。因此，开发具有抗生物膜特性的辅助治疗策略是一种很有前景的方法。在本研究中，我们研究了来源于皮肤杀菌肽的肽DCD-1L对金丝桃素纳米颗粒（HypNP）介导的抗微生物声动力疗法（aSDT）针对变形链球菌持续存在细胞生长和生物膜培养物的抗菌活性的影响。
在合成并确认HypNP后，通过棋盘法测定HypNP和DCD-1L的部分抑菌浓度（FIC）指数。评估HypNP-DCD-1L的细胞摄取和内源性活性氧（ROS）的产生，随后测定HypNP-DCD-1L对变形链球菌持续存在细胞生长和生物膜培养物的抗微生物声活性。然后评估变形链球菌持续存在细胞生长和生物膜培养物中的水不溶性细胞外多糖（EPS）以及gtfD、comDE和smuT基因的表达。
HypNP和DCD-1L联合对变形链球菌具有协同活性，FIC指数值为0.37。HypNP-DCD-1L介导的aSDT还显示出细菌细胞对其最高的细胞摄取和内源性ROS产生。当用HypNP-DCD-1L处理变形链球菌的生物膜和持续存在细胞，随后暴露于超声波时，观察到细菌数量分别减少了5.1个对数和3.8个对数（P<0.05）。根据数据，暴露于HypNP-DCD-1L介导的aSDT后，变形链球菌持续存在细胞生长和生物膜培养物中的EPS均显著降低（P<0.05）。此外，定量实时PCR数据表明，所有处理组的持续存在细胞在处理前后gtfD的极低表达谱具有高度相似性。而在HypNP-DCD-1L介导的aSDT处理后，与对照组相比，变形链球菌持续存在细胞生长和生物膜培养物中gtfD、comDE和smuT的表达水平显著降低（P<0.05）。
综合来看，本研究结果表明，超声波激活的HypNP-DCD-1L可以使变形链球菌生物膜和持续存在细胞声失活，并有效降低变形链球菌的致病力。因此，HypNP-DCD-1L介导的aSDT可能被认为是一种有前景的龋齿辅助治疗方法。
