Investigating bacterial-host interactions driving CF Pulmonary Exacerbations

描述（由申请人提供）：铜绿假单胞菌引起的慢性气道感染夺去了绝大多数囊性纤维化（CF）患者的生命。一旦确定感染，患者就会经常出现称为肺恶化的疾病发作。加重期间，肺部炎症和损伤增加，肺功能恶化，并出现明显的呼吸和全身症状。虽然有些耀斑会导致短暂的疾病，但四分之一的耀斑会导致永久性的肺功能衰退。这些事件的累积效应导致呼吸衰竭和死亡，通常在生命的第三个十年。不幸的是，导致病情恶化的机制仍然未知，而且很难开发出新的治疗方法。在这里，我们利用正在进行的临床试验的基础设施，以及关于感染铜绿假单胞菌群体内遗传多样性的新发现，作为研究恶化机制的工具。大多数CF感染是克隆的，这意味着感染群体是由单个分离物的后代组成的。在初步研究中，我们发现感染铜绿假单胞菌菌株在宿主体内进化产生遗传多样性（但克隆相关）的细菌种群。此外，进化的细菌亚群在已知影响宿主炎症和损伤反应的特征上存在差异。引起明显不同宿主反应的亚种群的存在可能对疾病表现有重大影响，因为我们的初步数据显示耀斑与感染种群组成的显着变化有关。我们将在这些发现的基础上检验假设，即在恶化开始时，感染铜绿假单胞菌种群组成的变化引发宿主反应，导致肺部炎症和损伤。母临床试验提供了一个不同寻常的机会，在人类受试者中测试这一假设。

DESCRIPTION (provided by applicant): Chronic airway infections with Pseudomonas aeruginosa claim the lives of the vast majority of cystic fibrosis (CF) patients. Once infection is established patients suffer frequent disease flares known as pulmonary exacerbations. During exacerbations, increased lung inflammation and injury produce worsening pulmonary function, and marked respiratory and systemic symptoms. While some flares produce transient illness, one out of four causes permanent lung function decline. The cumulative effect of these events produce respiratory failure and death, typically in the third decade of life. Unfortunately, the mechanisms that produce exacerbations remain unknown, and new treatments have been difficult to develop. Here we exploit the infrastructure of an ongoing clinical trial, and new findings about genetic diversity within infecting P. aeruginosa populations as tools to study exacerbation mechanisms. Most CF infections are clonal, meaning that the infecting population is composed of the progeny of a single isolate. In preliminary studies, we found that infecting P. aeruginosa strains evolve to produce genetically diverse (but clonally-related) bacterial populations within the host. Furthermore, evolved bacterial subpopulations differ in traits known to affect host inflammatory and injury responses. The presence of subpopulations that elicit markedly different host responses could have a major effect on disease manifestations, as our preliminary data shows that flares are associated with marked changes in infecting population composition. We will build on these findings to test the hypothesis that at the onset of exacerbations, changes in the composition of infecting P. aeruginosa populations elicit host responses leading to lung inflammation and injury. The parent clinical trial presents an unusual opportunity to test this hypothesis in human subjects.