光动力学抗真菌的作用及机理研究

Fungal infection is common clinical infectious diseases . AIDS patients due to decreased immunity have a great chance to suffer from fungal infections. In recent decades, the incidence of a variety of opportunistic fungal infections has considerably increased. But the traditional treatment is still limited to chemical agents, which has serious toxic side effects. Because of the well-known increase in antifungal chemical agents resistance among pathogenic microbes of all classes, the treatment of fungal infections becomes a daunting challenge. The problem is the fungal infections is hard to be cured and is easy to be relapsed, even cause a fatal disease complications. The growing resistance against commercially available antifungal drugs has renewed the search for alternative treatment modalities. Searching for the efficacy of new antifungal drug or a new therapeutic approach has become a worldwide hot topic. Photodynamic therapy (PDT) is a selective, non-invasive modality of treatment. Photodynamic medicine is a non-toxic side effects and resistant to treatment method. Our study shows that PDT has a great antibacterial effect on some tested bacteria, even some resistance drug Gram-positive bacteria such as Staphylococcus aureus.We will use colony forming unit phototoxicity assay to search effective photosensitisers on fungi such as Candida albicans and Cryptococcus neoformans by using different photosensitisers.Then the effective photosensitisers will use to detect the mechanism of antifungal PDT by using XTT metabolic assays and quantitative real-time PCR,as well as laser scanning confocal microscope. The project purpose is to ascertain the role and mechanism of PDT on fungi. This study will provide a reliable scientific basis for clinical application.

真菌感染是常见的临床感染性疾病，尤其是艾滋病患者因免疫力下降而感染真菌的机会大大增加，来自各种机会性真菌感染的发病率也逐年攀升。目前的治疗措施仍局限于化学制剂，毒副作用大，而且伴随着真菌对化学制剂的耐药性日益严重，真菌感染的治疗面临着严峻挑战，以致真菌感染反复发作，缠绵难愈，甚至引起致命性病发症。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。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，我们的前期针对某些菌谱的研究表明，光动力疗法具有较好的抗菌作用，且对耐药革兰氏阳性菌如金葡菌也有明显的杀灭作用。该项目旨在应用各种不同光敏剂及其特定波长的光波和能量对真菌（白色念珠菌和新型隐球菌）进行光毒性试验，筛选出有效光敏剂，进一步采用先进的技术手段检测光动力对真菌代谢、氧化应激反应等的变化，从而探明光动力疗法对真菌的作用及机制，为临床应用提供可靠依据。

白色念珠菌感染是临床常见和多发的机会性感染性疾病，尤其是艾滋病患者，口腔念珠菌病是最常见机会性感染之一，国内治疗HIV/AIDS合并口腔念珠菌病首选唑类抗菌药物，由于口腔念珠菌病长期反复发作，白色念珠菌分离株对氟康唑和伊曲康唑耐药性呈上升趋势。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。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。本研究通过体外实验筛选出有效杀灭白色念珠菌的光敏剂二甲基蓝(dimethylmethylene blue,DMMB)，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DMMB介导的APDT的关键分子作用机制，并将体外实验结果应用到动物实验并得到了印证，而且应用到艾滋病患者合并口腔白色念珠菌感染的治疗也得到了较好的治疗效果，为今后临床推广应用提供可靠的科学依据。