Biofilm Detachment Mechanisms in Chronic Lung Infections

描述(申请人提供)：铜绿假单胞菌生物被膜导致许多慢性感染，包括困扰支气管扩张患者的呼吸道感染、导致呼吸机相关性肺炎的气管内导管定植、医疗器械感染等。在生物膜中，细菌生活在基质包裹的群体结构中，这种生长模式会产生生理变化，导致显著的抗生素耐药性。尽管生物膜在疾病中很重要，但还没有开发出能够破坏它们的药物。有趣的是，生物膜细菌本身具有从生物膜分离的活性机制；这个过程被称为脱离。由于分离的细菌重新对杀戮敏感，这一过程可能在治疗上有用。这项工作的目的是研究铜绿假单胞菌生物膜脱离的潜在机制，并利用呼吸道生物膜感染模型研究脱离的病理后果。我们发现了一株具有超分离表型的铜绿假单胞菌变异株。该菌株过量生产生物表面活性物质鼠李糖脂，这是其加速生物膜脱离所必需的。主要研究内容如下：1.鼠李糖脂介导的生物膜脱离的机制是什么？我们将检查野生型和变异型菌株产生的鼠李糖脂的类型，并使用两种独立的方法来确定鼠李糖脂本身是否会导致生物膜脱落。微阵列分析将被用来寻找可能需要脱离的其他基因。2.体内生物膜脱落的后果是什么？使用我们的呼吸道生物被膜感染模型和同基因的高、低分离菌株，我们将调查诱导脱离的潜在风险，并确定脱离是否改善了宿主对微生物的清除。3.体内生物膜脱落是否会增加抗生素治疗的疗效？使用非分离菌株，呼吸道生物被膜模型中的感染对治疗具有极强的抗药性。在体外，生物膜脱落可以恢复抗生素的敏感性。我们将研究脱离是否会增加体内抗生素治疗的疗效。这些研究将模拟一种将传统抗生素与诱导生物膜脱离相结合的治疗策略。

DESCRIPTION (provided by applicant): P. aeruginosa biofilms cause many chronic infections including airway infections that afflict bronchiectasis patients, endotracheal tube colonization that leads to ventilator associated pneumonia, medical device infections, and others. In biofilms, bacteria live in matrix-encased group structures, and this growth mode produces physiologic changes that cause marked antibiotic resistance. In spite of the importance of biofilms in disease, no medical treatments have yet been developed to disrupt them. Interestingly, biofilm bacteria themselves possess active mechanisms to separate from biofilms; this process is known as detachment. Because detached bacteria regain sensitivity to killing, this process may be useful therapeutically. The goal of this work is to investigate a potential mechanism of P. aeruginosa biofilm detachment, and to study the pathological consequences of detachment using an airway biofilm infection model. We have discovered a P. aeruginosa variant strain with a hyper-detachment phenotype. This strain overproduces the bio-surfactant, rhamnolipid, which is required for its accelerated biofilm detachment. The following aims are proposed: 1. What is the mechanism of rhamnolipid-mediated biofilm detachment? We will examine the types of rhamnolipids produced by the wild type and variant strain, and use two independent methods to determine if rhamnolipids can, by themselves, cause biofilm detachment. Microarray analysis will be used to find other genes that may be needed for detachment. 2. What are the consequences of biofilm detachment in vivo? Using our airway biofilm infection model and isogenic hyper and hypo-detaching strains, we will investigate the potential risks of inducing detachment and determine if detachment improves clearance of the organisms by the host. 3. Will biofilm detachment in vivo increase the efficacy of antibiotic treatment? Using non-detaching strains, infections in the airway biofilm model are extremely resistant to treatment. In vitro, biofilm detachment restores antibiotic sensitivity. We will investigate whether detachment increases the efficacy of antibiotic treatment in vivo. These studies will model a treatment strategy that combines traditional antibiotics with induced biofilm detachment.