Pseudomonas aeruginosa lipid A

描述(申请人提供)：囊性纤维化患者(CF)患有慢性呼吸道感染的机会致病菌铜绿假单胞菌(PA)，并经历恶化，不可逆转的肺损伤导致过早死亡。这种损伤是由炎症过程介导的，至少部分是由于内毒素(IPS)的生物活性成分PA类脂A刺激天然免疫系统造成的。来自CF患者的PA分离株结构性地合成具有独特结构修饰的类脂A。这些结构的合成可能在CF肺疾病的发病机制中起重要作用。具有独特类脂A的PA可通过两种方式导致CF肺部疾病：通过增加宿主炎症反应，以及通过增加细菌对宿主天然免疫元件的抵抗力，如阳离子抗菌肽(CAMP)或抗生素。因此，我们建议通过鉴定参与其合成的基因，构建不能合成特定脂质A结构的PA突变株，并在肺部炎症模型中检测具有这些特定脂质A结构的PA及其对cAMP的易感性，来确定这些脂质A结构修饰与CF肺部疾病的相关性和调节。这些研究将提供对导致CF肺部疾病的细菌机制的洞察，包括脂质A修饰酶的作用。这些酶可能为治疗PA肺部感染及其炎症后果的药物的开发提供新的靶点。 这项建议的重点是进一步定义囊性纤维化特异性脂A的合成和调节所需的酶，A是各种铜绿假单胞菌临床分离背景中脂多糖的生物活性成分。囊性纤维化患者分离的铜绿假单胞菌通过独特的结构修饰合成类脂A。此外，还将确定特定的类脂A结构在调节宿主天然免疫系统和炎症反应中的作用。这些研究可能导致确定候选蛋白靶标，这些靶标可以阻止Cf特异性脂质A结构的合成，并使铜绿假单胞菌更容易受到宿主细胞杀伤和/或传统抗生素干预的影响。

DESCRIPTION (provided by applicant): Patients with cystic fibrosis, (CF) suffer from chronic airway infections with the opportunistic pathogen Pseudomonas aeruginosa (PA), and experience worsening, irreversible lung injury leading to premature death. This injury is mediated by an inflammatory process that results, at least in part, from stimulation of the innate immune system by PA lipid A, the bioactive component of lipopolysaccharide (IPS). PA isolates from CF patients constitutively synthesize lipid A with unique structural modifications. The synthesis of these structures may be essential for CF lung disease pathogenesis. PA with unique lipid A could contribute to CF lung disease in two ways: by increasing host inflammatory responses, and by increasing bacterial resistance to elements of host innate immunity, such as cationic antimicrobial peptides (CAMPs) or antibiotics. We therefore propose to identify the relevance and regulation of these lipid A structural modifications to CF pulmonary disease by identifying genes involved in their synthesis, constructing isogenic PA mutant strains unable to synthesize specific lipid A structures, and testing PA with these specific lipid A structures in models of lung inflammation and their susceptibility to CAMPs. These studies will provide insight into bacterial mechanisms that contribute to CF lung disease, including the role of lipid A modifying enzymes. Such enzymes may provide novel targets for the development of drugs to treat PA lung infections and their inflammatory consequences. The focus of this proposal is to further define enzymes required for the synthesis and regulation of cystic fibrosis-specific lipid A, the bioactive component of lipopolysaccharide in a variety of Pseudomonas aeruginosa clinical isolate backgrounds. P. aeruginosa isolates from patients with cystic fibrosis constitutively synthesize lipid A with unique structural modifications. In addition, the role of specific lipid A structures in modulation of the host the innate immune system and inflammatory responses will be determined. These studies could lead to the identification of candidate protein targets that block the synthesis of CF-specific lipid A structures and render P. aeruginosa more susceptible to host cell killing and/or conventional antibiotic intervention.