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，即使是由于对抗生素抗药性的病原体引起的。这是悖论，也是我们旨在解决的问题。 微生物种群会产生持久性的，不是突变体的休眠细胞，而是对抗生素耐受性的野生型的表型变异。持久者的存在似乎可以解释治疗悖论：一种抗生素消除了大部分人群，一旦其浓度下降，幸存的言论就开始分裂并重新建立感染。但是，用抗生素在体外长期治疗应模仿体内治疗可以消除这些休眠细胞。假设。我们假设负责无法治疗的感染的药物是一个超级症状细胞，它带有高质突变并引起应力反应。 重复应用高水平的抗生素在体外选择，用于大肠杆菌髋关节（高晶状体）突变体，该突变体的持久细胞水平增加。根据我们的数据，与野生型持久性相比，髋部细胞也更容易耐药。我们认为，将致命剂量的抗生素定期应用于慢性感染患者将类似地选择髋关节突变体。对感染铜绿假单胞菌的囊性纤维化患者的纵向分离株的分析表明，迟到但不是早期分离株确实是髋关节突变体。重复剂量的抗生素的治疗似乎可能在许多情况下选择髋关节突变体，而这些病原体的髋关节突变体可能最终导致疾病的发病率和患者死亡。 除了髋关节突变外，似乎还有另一个被忽视但可能有可能导致压力反应的重要组成部分。到目前为止，我们已经知道两种看似相反的细胞存活策略 - 休眠，它们关闭了功能并创造了持久的细胞。以及诱导应力反应（热休克，DNA修复，氧化应激等），可积极保护细胞免受有害条件的影响。我们建议这两种策略实际上相互补充。如果在表达应激蛋白的人群中形成持久性，则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，病原体暴露于氧化剂，DNA破坏剂，膜作用剂中，似乎几种应激反应的表达是一种规范。然后，最终的幸存者是一种持久的携带髋关节突变的持久性，该突变是在表达压力反应的种群中形成的。正是这位超级疾病可能导致了许多不可治疗的疾病，这将是我们调查的重点。实验计划将解决以下相互关联的问题：髋关节突变体是慢性感染的重要组成部分吗？是否存在将髋关节突变与压力反应表达的表达相结合的超级群体？耐受性与抗性类似，是一种传播性状吗？ 公共卫生相关性：在这个项目中，我们将寻找能够进入高度耐受现有抗生素的病原体的突变体。我们的发现可能会改变我们观察传染病的方式，并将为发现完全消除感染的药物提供合理的方法。