增强Ⅱ型光敏剂介导的光动力抗白色念珠菌作用与机制研究

In clinic antifungal resistances is becoming more and more serious, which always becomes an important and hot topic in the research of infectious diseases. Our previous study shows that non-toxic iodide anion has a great antibacterial potentiation on Type I photosensitizer methylene blue mediated antimicrobial/antifungal photodynamic therapy (aPDT) effect. According to these findings, in this project we hypothesize that iodide anion may be able to potentiate type Ⅱ photosensitizer (such as photofrin, PF) mediated photodynamic inactivation of Candida albicans in vitro and in vivo. The mechanism might be that PF-PDT produces singlet oxygen, which can oxidize iodide anion .The first is a one-electron transfer to produce iodide radicals and give superoxide anions. Iodide radicals will dimerize to give molecular iodine. In order to demonstrate this hypothesis, we will use a series of photophysical and photochemical tests to demonstrate that iodide anion potentiates PF-PDT by producing iodide radicals and molecular iodine . The mechanism will provide scientific basis for developing new antifungal photodynamic therapy.

临床真菌耐药性日益突出,一直成为感染科研究的重要课题和热点。我们前期通过抗菌光动力治疗(aPDT)研究发现,I型光敏剂亚甲基蓝在无毒碘阴离子作用下,能够明显增强其抗菌效果, 鉴此提出假设:通过体外和在体真菌-白色念珠菌感染模型,Ⅱ型光敏剂光敏素（PF）在碘阴离子干预下,在光动力作用下,可能具有协同增强抗白色念珠菌效应, 并通过一系列的光物理和光化学检测，印证在Ⅱ型光敏剂PF-aPDT中产生的单态氧能氧化碘阴离子,通过电子转移方式继而产生碘自由基或超氧阴离子，碘自由基又可产生碘分子，从而揭示碘阴离子增强Ⅱ型光敏剂介导的光动力杀白色念珠菌的作用机制，为开发光动力抗真菌新疗法提供可靠的科学依据。

白色念珠菌感染是临床常见和多发的机会性感染性疾病，由于临床真菌耐药性发展迅速并日益突出,寻找安全、抗耐药、疗效好的新型抗真菌药物或新的治疗途径已成为国内外研究的热点和重要课题。光动力医学属于一种新兴、无创伤、无毒副作用、无耐药性的治疗方法。本研究以美国FDA已批准应用于临床的II型光敏剂光敏素（Photofrin，简称PF）、无毒的氯化钾（potassium chloride，简称KI）和白色念珠菌为研究对象，观察比较在KI存在与否的情况下PF-PDT杀灭白色念珠菌作用效果，同时应用不同的荧光分子探针，分光光度计技术和激光共聚焦荧光显微镜技术，阐明了KI增强光敏剂 PF介导的aPDT的关键分子作用机制：1O2 + I- O2- + I；2I I2；2O2- + 2H+ O2 + H2O2 。同时进一步利用从PF-PDT体外实验筛选出且能够杀灭白色念珠菌所需的光波波长、光能量密度和光敏剂PF浓度及增强PF-PDT所需的理想无毒的KI浓度的最佳组合，通过特定的 PF-PDT方案应用到小鼠局部感染动物模型上并得到了印证，为今后临床推广应用提供可靠的科学依据。