Impact of Alginate Overproduction on P. aeruginosa LPS O Antigen Expression

海藻酸盐过量生产对铜绿假单胞菌 LPS O 抗原表达的影响

• 批准号: 9317789
• 负责人: Joanna B Goldberg
• 金额: $ 19.25万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-01-19 至 2018-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9317789
• 关键词: Age; Alginates; Antibiotic Resistance; Bacteria; Bronchiectasis; Chronic; Clinical; Cystic Fibrosis; Development; Environment; Genes; Genetic; Genetic Transcription; Genotype; Goals; Gram-Negative Bacteria; Immune response; Infection; Integration Host Factors; Laboratories; Length; Life; Life Expectancy; Link; Lipopolysaccharides; Lung; Molecular; Monitor; O Antigens; Patient Isolators; Patients; Phenotype; Polysaccharides; Population; Process; Pseudomonas aeruginosa; Pulmonary Fibrosis; Repression; Research Project Grants; Respiratory Tract Infections; Signal Transduction; Therapeutic Intervention; cystic fibrosis patients; improved; mouse model; mucoid; pathogen; prevent; respiratory; targeted treatment

PROJECT SUMMARY/ABSTRACT. Pseudomonas aeruginosa, a Gram-negative bacterium, is an important opportunistic pathogen and the leading cause of chronic life-threatening lung infections in cystic fibrosis (CF) patients. P. aeruginosa is naturally antibiotic resistant and infections with this bacterium are notoriously difficult to treat. About 70% of CF patients are infected with P. aeruginosa by age 18 and the mean life expectancy is less than 40 years. A better understanding of how this bacterium evolves to cause these chronic respiratory infections is needed. Numerous phenotypic changes take place as P. aeruginosa transitions from the environment to causing life-shortening chronic CF lung infections. The emergence of isolates with a mucoid phenotype, due to the overproduction of the exopolysaccharide alginate is the most conspicuous; the isolation of mucoid strains is a prognosticator of clinical decline in these patients. Mucoid strains also have an additional less obvious polysaccharide alteration: these strains are generally lack lipopolysaccharide (LPS) O antigen, a phenotype referred to as “LPS-rough”. Interestingly, this same conversion to a mucoid, LPS-rough form is prominent in P. aeruginosa isolates from patients with non-CF chronic bronchiectasis. In rare mucoid strains that do express LPS O antigen, different lengths of LPS O antigen are expressed compared to non-mucoid LPS-smooth strains: while LPS isolated from non-mucoid strains includes both long and very long O antigen, LPS isolated from mucoid strains shows decreased expression of very long O antigen but the same expression of long O antigen, which we suggest represents a transition state between the initial- and chronic-infecting forms. The goal of this 2-year Exploratory/Developmental Research Grant is to determine how mucoidy and loss of O antigen (as well as other genotypes) emerge during chronic colonization and how the bacteria and host respond to these infections. In Specific Aim 1, we will utilize the laboratory strain PAO1 and its mucoid derivative, PDO300, in a newly described murine model of chronic respiratory colonization and will follow the phenotypes and genotypes of the strains emerging and evolving during colonization as well as the bacterial and host response to infection. In Specific Aim 2, we will take a molecular approach to identify the genetic regulatory mechanisms controlling very long O antigen in a mucoid LPS-smooth strain and assess how alginate represses very long O antigen. The discovery of factors involved in the repression wzz2 (the gene which encodes the very long O antigen chain length regulator) will provide the relevant targets for therapeutic intervention. If we can inhibit the repression wzz2, this may set up a situation where the bacteria cannot maintain the mucoid phenotype and therefore would not be shielded from the innate host immune response or evolve into a chronic-colonizing form. The long-term goal of these studies will be to identify bacterial factors that can be targeted to inhibit chronic lung infection and host factors that can increase bacterial clearance and therefore improve the lives of CF patients.

项目总结/摘要。 铜绿假单胞菌是一种重要的条件致病菌， 囊性纤维化（CF）患者中慢性危及生命的肺部感染的主要原因。铜绿假单胞菌是 这种细菌的天然抗生素抗性和感染是众所周知的难以治疗。 CF患者在18岁时感染铜绿假单胞菌，平均预期寿命不到40岁。一 需要更好地了解这种细菌是如何演变成这些慢性呼吸道感染的。 当铜绿假单胞菌从环境中转变为致病菌时， 缩短寿命的慢性CF肺部感染。粘液样表型分离株的出现，由于 胞外多糖藻酸盐的过量生产是最明显的;粘液样菌株的分离是一种 这些患者的临床下降的指标。粘液型菌株还具有额外的不太明显的 多糖改变：这些菌株通常缺乏脂多糖（LPS）O抗原， 称为“LPS粗”。有趣的是，这种向粘液样、LPS粗糙形式的转化在P. 铜绿假单胞菌分离物来自非CF慢性支气管扩张患者。在罕见的粘液型菌株中， LPS O抗原，与非粘液LPS-光滑相比，表达不同长度的LPS O抗原 菌株：虽然从非粘液样菌株分离的LPS包括长和非常长的O抗原，但从非粘液样菌株分离的LPS包括长和非常长的O抗原。 粘液样菌株的长O抗原表达减少，但长O抗原表达相同 抗原，我们认为这代表了初始和慢性感染形式之间的过渡状态。 这项为期2年的探索性/发展性研究资助的目标是确定粘液性和 O抗原（以及其他基因型）的丢失在慢性定植期间出现，以及细菌和 宿主对这些感染有反应。在特定目标1中，我们将利用实验室菌株PAO 1及其粘液 在新描述的慢性呼吸道定植的鼠模型中，PDO 300衍生物，并将遵循 在定殖过程中出现和进化的菌株的表型和基因型以及细菌 和宿主对感染的反应在具体目标2中，我们将采取分子方法来识别遗传 调节机制控制非常长的O抗原在粘液脂多糖光滑菌株，并评估如何 藻酸盐抑制非常长的O抗原。参与抑制wzz 2（基因）的因子的发现 其编码非常长的O抗原链长度调节物）将提供治疗性的相关靶标。 干预如果我们能抑制wzz 2的抑制，这可能会造成细菌不能 维持类粘蛋白表型，因此不会被先天性宿主免疫应答屏蔽，或 进化成一种长期殖民的形式。这些研究的长期目标将是确定细菌因素 可以靶向抑制慢性肺部感染和宿主因子，这些因子可以增加细菌清除， 从而改善CF患者的生活。