Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran.
Costerton Biofilm Center, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Photodiagnosis Photodyn Ther. 2019 Sep;27:467-473. doi: 10.1016/j.pdpdt.2019.07.025. Epub 2019 Jul 27.
Antimicrobial photodynamic inactivation (APDI) is a new therapeutic modality which needs more precision during application due to the possibility of exposure of bacteria to sub-lethal doses (sAPDI). In this study, we aimed to evaluate the effect of sAPDI on Pseudomonas aeruginosa quorum sensing (QS) and c-di-GMP signaling which are important virulence factor regulatory systems.
Biofilm formation, pyoverdine, pyocyanin and protease production of P. aeruginosa was evaluated before and after a single sAPDI treatment with 0.8 mM methylene blue (MB) plus 1, 2, and 5-min irradiation with red laser light. Fluorescent lasB, rhlA, pqsA, and cdrA reporters of P. aeruginosa PAO1 and P. aeruginosa ΔmexAB-oprM were treated individually with sAPDI and the regulatory signals were detected. The gene expressions were also assessed after sAPDI using quantitative real-time PCR analysis.
Morphological observations and molecular assessments indicated that sAPDI with 0.8 mM MB along with 2- and 5-min irradiation led to an increase in the expression of the Las QS system and c-di-GMP signaling, while 1 min irradiation revealed dissimilar results (increase in lasB expression and decrease in c-di-GMP levels). Expression of rhlA and pqsA did not change in response to sAPDI. Further, a severe lethal effect of sAPDI was observed in P. aeruginosa ΔmexAB-oprM as compared with the wild type strain, whilst there was no difference in QS and c-di-GMP levels as detected by reporters between treated and untreated samples.
The results suggest that sAPDI affects QS and c-di-GMP signaling inP. aeruginosa in a time-dependent manner.
抗菌光动力灭活（APDI）是一种新的治疗方式，由于细菌可能暴露于亚致死剂量（sAPDI），因此在应用过程中需要更精确。在这项研究中，我们旨在评估 sAPDI 对铜绿假单胞菌群体感应（QS）和 c-di-GMP 信号转导的影响，这是重要的毒力因子调节系统。
用 0.8mM 亚甲基蓝（MB）加 1、2 和 5 分钟红光照射对铜绿假单胞菌进行单次 sAPDI 处理前后，评估铜绿假单胞菌生物膜形成、绿脓菌素、吡咯菌素和蛋白酶的产生。单独用 sAPDI 处理铜绿假单胞菌 PAO1 和 P. aeruginosa ΔmexAB-oprM 的荧光 lasB、rhlA、pqsA 和 cdrA 报告子，并检测调节信号。sAPDI 后还使用定量实时 PCR 分析评估基因表达。
形态学观察和分子评估表明，用 0.8mM MB 联合 2 和 5 分钟照射的 sAPDI 导致 Las QS 系统和 c-di-GMP 信号转导的表达增加，而 1 分钟照射则显示出不同的结果（lasB 表达增加，c-di-GMP 水平降低）。rhlA 和 pqsA 的表达不因 sAPDI 而变化。此外，与野生型菌株相比，sAPDI 对 P. aeruginosa ΔmexAB-oprM 表现出严重的致死效应，而用报告子检测到处理和未处理样品之间的 QS 和 c-di-GMP 水平没有差异。
结果表明，sAPDI 以时间依赖的方式影响 P. aeruginosa 的 QS 和 c-di-GMP 信号转导。
