Photodynamic Therapy of Localized Infections

局部感染的光动力疗法

基本信息

批准号：
8013056
负责人：
MICHAEL R HAMBLIN
金额：
$ 42.78万
依托单位：
MASSACHUSETTS GENERAL HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2003
资助国家：
美国
起止时间：
2003-07-01 至 2012-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8013056
关键词：
Acute Animal Experiments Animal Model Antibiotic Resistance Antibiotics Area Aspergillus fumigatus Bacteria Binding Burn injury Candida albicans Cell Wall Cells Cessation of life Chronic Combined Modality Therapy Destinations Dyes Focal Infection Funding Generations Goals Grant Health Hydrogen Peroxide Image Infection Invaded Lesion Light Lighting Lipids Lysine Mediating Methods Microbe Modeling Molecular Mouse Strains Nucleic Acids Oxygen Photochemotherapy Photosensitizing Agents Prevalence Procedures Proteins Pseudomonas aeruginosa Reactive Oxygen Species Research Sepsis Site Staphylococcus aureus Surgical wound Testing Tissues Virulence Factors Visible Radiation amino group antimicrobial cancer cell cell killing cell type chlorin e6 clinical practice cytotoxic extracellular fluorescence imaging fungus in vivo killings mouse model novel pathogenic bacteria

项目摘要

DESCRIPTION (provided by applicant): The overall goal of this proposal is to continue to explore a novel photochemical method for killing antibiotic resistant pathogenic bacteria or fungi in models of localized infection. Photodynamic therapy (PDT) employs a non-toxic dye termed a photosensitizer (PS) and low intensity visible light, which in the presence of oxygen produce cytotoxic species that damage proteins, lipids and nucleic acids and kill cells. PDT has the advantage of dual selectivity in that the PS can be targeted to its destination cell type or tissue, and in addition the illumination can be spatially directed to the area of infection. In the previous funding period we established that polycationic delivery vehicles such as poly-L-lysine could be conjugated to PS such as chlorin(e6), and these molecular delivery vehicles for PS increased the selective binding to bacteria and enabled the PS to penetrate the cell walls of Gram (-) bacteria to dramatically potentiate light-mediated killing.. We used luminescent bacteria and a low-light imaging camera to demonstrate that PDT will kill both Gram (-) species (eg Pseudomonas aeruginosa) and Gram (+) species (eg Staphylococcus aureus) in vivo in animal models of wounds, burns and deep established infections. Localized PDT may have an additional advantage in that it is also possible to inactivate secreted extracellular virulence factors that pathogenic bacteria use to establish infections and invade tissue. This competing renewal will seek to explore new ways of increasing the potency and applicability of antimicrobial PDT. Four specific aims will focus on (1) studying the photochemical mechanisms of photodynamic inactivation of microbes (that may be very different from cancer cells) with the aim of devising simple combination treatments; (2) investigating the new discovery that low non-toxic concentrations of hydrogen peroxide dramatically potentiate antimicrobial PDT by orders of magnitude; (3) synthesizing and testing a third generation polycationic PS conjugates with quaternized amino groups that retain cationic character under all conditions; (4) testing the above treatments in mouse models of acute or chronic wounds and burns infected with pathogenic bacteria (P. aeruginosa or S. aureus), together with an entirely new model of spectrally resolved fluorescence imaging of GFP Candida albicans or Aspergillus fumigatus growing in traumatic lesions in various strains of mice. These avenues of research are expected to suggest simple procedures to optimize antimicrobial PDT and hasten its wide introduction into clinical practice. PUBLIC HEALTH RELEVANCE The alarming rise in prevalence of antibiotic resistance amongst pathogenic bacteria has led to worries that previously treatable infections could soon be incurable. Traumatic or surgical wounds and burns are common sites of infection that can progress to sepsis and death if they fail to be controlled by antibiotics. Photodynamic therapy (PDT) involves a combination of non- toxic dyes and harmless visible light that in combination produce highly toxic reactive oxygen species. If the dye is targeted to the bacterial cell PDT can be a highly effective local antimicrobial therapy with little damage to host tissue. This application seeks to determine the optimum parameters for antimicrobial PDT and will look at new synergistic combination therapies.

描述（由申请人提供）：本提案的总体目标是继续探索一种新的光化学方法，用于在局部感染模型中杀死抗生素耐药性病原细菌或真菌。光动力疗法（PDT）采用一种称为光敏剂（PS）的无毒染料和低强度可见光，在氧气存在的情况下产生细胞毒性物质，破坏蛋白质、脂质和核酸并杀死细胞。 PDT 具有双重选择性的优点，因为 PS 可以靶向其目标细胞类型或组织，此外照明可以在空间上定向到感染区域。在之前的资助期间，我们确定聚赖氨酸等聚阳离子递送载体可以与二氢卟酚（e6）等 PS 缀合，这些 PS 分子递送载体增加了与细菌的选择性结合，并使 PS 能够渗透到细菌中。革兰氏 (-) 细菌的细胞壁，显着增强光介导的杀伤作用。我们使用发光细菌和低光成像相机来证明 PDT 可以杀死革兰氏 (-) 物种（例如铜绿假单胞菌）和伤口、烧伤和深度感染动物模型中的革兰氏（+）菌种（例如金黄色葡萄球菌）。局部PDT可能具有额外的优势，因为它还可以灭活病原菌用来建立感染和侵入组织的分泌的细胞外毒力因子。这一竞争性更新将寻求探索提高抗菌 PDT 效力和适用性的新方法。四个具体目标将集中于（1）研究微生物（可能与癌细胞非常不同）光动力灭活的光化学机制，旨在设计简单的组合治疗； (2) 研究新发现，即低无毒浓度的过氧化氢可显着增强抗菌 PDT 的数量级； (3) 合成并测试第三代具有季铵化氨基的聚阳离子PS缀合物，该缀合物在所有条件下都保留阳离子特性； (4) 在感染病原菌（铜绿假单胞菌或金黄色葡萄球菌）的急性或慢性伤口和烧伤小鼠模型中测试上述治疗方法，以及绿色荧光蛋白白色念珠菌或烟曲霉生长的全新光谱分辨荧光成像模型在不同品系小鼠的创伤性病变中。这些研究途径预计将提出优化抗菌 PDT 的简单程序，并加速其广泛应用于临床实践。公共卫生相关性病原菌中抗生素耐药性的流行率惊人上升，引发了人们的担忧，即以前可治疗的感染可能很快就会变得无法治愈。外伤或手术伤口和烧伤是常见的感染部位，如果不能用抗生素控制，可能会发展为败血症和死亡。光动力疗法（PDT）涉及无毒染料和无害可见光的组合，两者结合产生剧毒活性氧。如果染料针对细菌细胞，PDT 可以成为一种高效的局部抗菌疗法，对宿主组织的损伤很小。该申请旨在确定抗菌 PDT 的最佳参数，并将研究新的协同联合疗法。