Adaptation of Pseudomonas aeruginosa in virulence and metabolism: requirements for chronic lung infection in cystic fibrosis patients

慢性铜绿假单胞菌（PA）肺炎是囊性纤维化（CF）患者发病和死亡的主要原因。在PA从自由生活的细菌转变为肺部病原体的过程中，大量致病性基因被上调以建立CF肺定殖和急性感染。在慢性感染期间，PA变体出现毒力减弱的表型，这可能是由于发炎的CF肺环境的选择。通过对来自终末期CF肺病的PA分离株的详细分析，我们确定了这些PA分离株的转录组和蛋白质组的实质性变化，这些变化可能使PA能够在CF肺中建立终身持久性，并且是所谓的慢性毒力模式（cVP）的特征。这些变化影响代谢途径和应激反应，可能导致PA在CF气道的敌对和缺氧环境中的适应性和代谢竞争力增加。选择PA代谢变体，增加二羧酸摄取、三碳酸循环组分（例如异柠檬酸脱氢酶）、精氨酸代谢以及氧化还原活性蛋白（天青蛋白、细胞色素C过氧化物酶）似乎是cVP的典型特征。在模拟气道生长条件（限氧、人工CF痰液培养基）下PA生长期间，这些因子中的几个也上调，这强调了它们与PA肺持久性的代谢相关性。本提案的主要目的是阐明PA代谢适应的分子机制以及cVP对CF肺炎的影响。CF肺疾病中PA的cVP特征可能导致更好地理解PA慢性化脓性感染的发病机制，并将有助于开发改进的抗菌治疗。

Chronic Pseudomonas aeruginosa (PA) pneumonia is the major cause of morbidity and mortality among patients suffering from cystic fibrosis (CF). During transition of PA from free-living bacterium to a pulmonary pathogen, a large set of pathogenicity genes is upregulated to establish CF lung colonization and acute infection. During chronic infection PA variants emerge with virulence-attenuated phenotypes probably due to selection by the inflamed CF lung environment. By a detailed analysis of PA isolates from end-stage CF lung disease we identified substantial changes in the transcriptome and proteome of these PA isolates that probably enable PA to establish life-long persistence in the CF lung and are characteristic for so-called chronic virulence pattern (cVP). These changes affect metabolic pathways and stress-response that may lead to increased fitness and metabolic competitiveness of PA in the hostile and hypoxic environment of CF airways. The selection of metabolic variants of PA with increase in dicarboxylate uptake, components of the tricarbon acid cycle (e.g. isocitrate dehydrogenase), arginine metabolism as well as redox active proteins (azurin, cytochrom C peroxidase) seems to be typical for cVP. Several of these factors were also up-regulated during growth of PA under simulated airway growth conditions (oxygen-restriction, artificial CF sputum medium) underlining their metabolic relevance for PA lung persistence. The major aim of this proposal is to unravel the molecular mechanism of metabolic adaptation of PA and the impact of cVP in CF pneumonia. The characterization of cVP of PA in CF lung disease may lead to a better understanding of the pathogenesis of chronic suppurative infection by PA and will help to develop improved antimicrobial therapies.