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.

项目摘要/摘要。 铜绿假单胞菌（Pseudomonas aeruginosa）是一种革兰氏阴性菌，是一种重要的条件致病菌， 囊性纤维化 (CF) 患者慢性危及生命的肺部感染的主要原因是铜绿假单胞菌。 众所周知，这种细菌对抗生素具有天然耐药性，并且约 70% 的感染很难治疗。 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。 需要更好地了解这种细菌如何进化以引起这些慢性呼吸道感染。 当铜绿假单胞菌从环境转变为致病菌时，会发生许多表型变化。 具有粘液表型的分离株的出现，导致寿命缩短。 藻酸胞外多糖的过量产生是最明显的，粘液菌株的分离是 这些患者的粘液样菌株的临床预测指标也有一个不太明显的变化。 多糖改变：这些菌株通常缺乏脂多糖（LPS）O抗原，这是一种表型 被称为“LPS-rough”的座右铭，这种向粘液、LPS-rough 形式的转换在 P. 铜绿假单胞菌从患有非 CF 慢性支气管扩张症的患者中分离出来，在罕见的粘液样菌株中确实表达。 LPS O抗原，与非粘液LPS-smooth相比，表达不同长度的LPS O抗原 菌株：虽然从非粘液菌株分离的 LPS 包含长 O 抗原和极长 O 抗原，但分离的 LPS 粘液样菌株显示极长 O 抗原的表达减少，但长 O 抗原的表达相同 抗原，我们认为它代表了初始感染形式和慢性感染形式之间的过渡状态。 这项为期 2 年的探索性/发展性研究补助金的目标是确定粘液和 O 抗原（以及其他基因型）的丧失在慢性定植过程中出现，以及细菌和细菌如何 在具体目标 1 中，我们将利用实验室菌株 PAO1 及其粘液。 衍生物，PDO300，在新描述的慢性呼吸道定植小鼠模型中，并将遵循 定植过程中出现和进化的菌株以及细菌的表型和基因型 在具体目标 2 中，我们将采用分子方法来识别遗传。 控制粘液样 LPS 平滑菌株中非常长的 O 抗原的调节机制，并评估如何 藻酸盐抑制很长的 O 抗原。发现参与抑制 wzz2 的因子（基因）。 编码非常长的O抗原链长度调节剂）将为治疗提供相关靶点 如果我们能够抑制 wzz2 的抑制，这可能会造成细菌无法抑制的情况。 维持粘液样表型，因此不会免受宿主先天免疫反应的影响或 这些研究的长期目标是确定细菌因素。 可以靶向抑制慢性肺部感染和可以增加细菌清除率的宿主因素 从而改善 CF 患者的生活。