Super-persistent cells and the paradox of untreatable infections

超级持久细胞和无法治疗的感染的悖论

• 批准号: 7764848
• 负责人: Kim Lewis
• 金额: $ 100.85万
• 依托单位: NORTHEASTERN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-25 至 2014-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7764848
• 关键词: Address; Antibiotic Resistance; Antibiotics; Cell Survival; Cells; Cessation of life; Chronic; Communicable Diseases; Complement; DNA Damage; DNA Repair; Data; Disease; Dose; Drops; Escherichia coli; Heat shock proteins; Heating; In Vitro; Infection; Investigation; Membrane; Morbidity - disease rate; Mutation; Oxidants; Patients; Pharmaceutical Preparations; Population; Proteins; Pseudomonas aeruginosa; Resistance; Shock; Stress; Survivors; Variant; biological adaptation to stress; cystic fibrosis patients; in vivo; longitudinal analysis; microbial; mutant; oxidation; pathogen; public health relevance; stress protein; trait

DESCRIPTION (provided by applicant): Infectious disease is often untreatable, even when caused by a pathogen that is not resistant to antibiotics. This is the paradox, and the problem that we aim to solve. Microbial populations produce persisters, dormant cells that are not mutants, but phenotypic variants of the wild type that are tolerant to antibiotics. It seemed possible that the presence of persisters could explain the treatment paradox: an antibiotic eliminates most of the population, and once its concentration drops, the surviving persisters start dividing and reestablish the infection. However, prolonged treatment of persisters in vitro with antibiotics which should emulate the in vivo therapy eliminates these dormant cells. The hypothesis. We hypothesize that the agent responsible for untreatable infections is a super-persister cell which carries a high-persister mutation and has induced stress responses. Repeated application of high levels of antibiotics in vitro selects for E. coli hip (high-persister) mutants that have an increased level of persister cells. According to our data, the hip cells are also more drug-tolerant as compared to wild type persisters. We reasoned that periodic application of lethal doses of antibiotics to patients with chronic infections will similarly select for hip mutants. Analysis of longitudinal isolates from a cystic fibrosis patient infected with P. aeruginosa showed that late, but not early isolates are indeed hip mutants. It seems possible that therapy with repeated doses of antibiotic selects hip mutants in many if not all pathogens, and it is these presently overlooked tolerant (rather than resistant) mutants that are ultimately responsible for morbidity of the disease and for the death of a patient. Apart from hip mutations, there seems to be another overlooked, but potentially critical component contributing to tolerance - stress responses. So far, we have known of two seemingly opposite strategies of cell survival - dormancy, which shuts down functions and creates persister cells; and induction of stress responses (heat shock, DNA repair, oxidation stress, etc.) that actively protect the cell from noxious conditions. We propose that these two strategies actually complement each other. If a persister is formed in a population that had expressed stress proteins, then it will shut down antibiotic targets, while retaining protective proteins which will help it survive. In the body, a pathogen is exposes to oxidants, DNA damaging agents, membrane acting agents, and it seems that expression of several stress responses is a norm. The ultimate survivor is then a persister carrying a hip mutation which is formed in a population expressing stress responses. It is this super-persister that is probably responsible for much of untreatable disease and will be the focus of our investigation. The experimental plan will address the following interrelated questions: are hip mutants an important part of chronic infection? Are there super-persisters that combine hip mutations with expression of stress responses? Is tolerance, similarly to resistance, a transmissible trait? PUBLIC HEALTH RELEVANCE: In this project, we will search for mutants of pathogens that are able to enter into a state of dormancy highly tolerant to existing antibiotics. Our findings are likely to change the way we view infectious diseases and will provide rational approaches for discovering drugs that completely eradicate the infection.

描述（由申请人提供）：传染病通常是无法治疗的，即使是由对抗生素不具有耐药性的病原体引起的。这就是悖论，也是我们要解决的问题。 微生物群体产生持久细胞，即休眠细胞，它们不是突变体，而是对抗生素具有耐受性的野生型表型变体。持久性细菌的存在似乎可以解释治疗悖论：抗生素消除了大多数群体，一旦其浓度下降，幸存的持久性细菌就开始分裂并重新建立感染。然而，在体外用抗生素对持续存在的细胞进行长期治疗（应效仿体内治疗）会消除这些休眠细胞。假设。我们假设导致无法治疗的感染的病原体是超级持久细胞，它携带高持久突变并诱导应激反应。 体外重复应用高水平抗生素会选择具有增加的持久细胞水平的大肠杆菌髋（高持久）突变体。根据我们的数据，与野生型持续细胞相比，髋细胞也更具耐药性。我们推断，对慢性感染患者定期使用致死剂量的抗生素也会同样选择髋关节突变体。对感染铜绿假单胞菌的囊性纤维化患者的纵向分离株进行的分析表明，晚期分离株而非早期分离株确实是髋部突变体。重复剂量的抗生素治疗似乎有可能在许多（如果不是全部）病原体中选择髋部突变体，而正是这些目前被忽视的耐受（而不是抗性）突变体最终导致了疾病的发病和患者的死亡。 除了髋部突变之外，似乎还有另一个被忽视但可能对耐受性至关重要的因素——压力反应。到目前为止，我们已经知道两种看似相反的细胞生存策略：休眠，关闭功能并产生持久细胞；诱导应激反应（热休克、DNA 修复、氧化应激等），积极保护细胞免受有害条件的影响。我们认为这两种策略实际上是相辅相成的。如果在表达应激蛋白的群体中形成持续细胞，那么它将关闭抗生素靶标，同时保留有助于其生存的保护蛋白。在体内，病原体会暴露于氧化剂、DNA 损伤剂、膜作用剂，并且表达多种应激反应似乎是一种常态。最终的幸存者是携带髋部突变的持久者，这种突变是在表达应激反应的人群中形成的。正是这种超级顽固分子可能造成了许多无法治愈的疾病，并将成为我们调查的重点。该实验计划将解决以下相互关联的问题：髋关节突变是慢性感染的重要组成部分吗？是否存在将髋部突变与应激反应表达结合起来的超级持久者？与抵抗力类似，耐受性是一种可遗传的特征吗？ 公共卫生相关性：在这个项目中，我们将寻找能够进入对现有抗生素高度耐受的休眠状态的病原体突变体。我们的发现可能会改变我们看待传染病的方式，并将为发现彻底根除感染的药物提供合理的方法。