Humoral immunity against the M. tuberculosis kasB persistent mutant

针对结核分枝杆菌 kasB 持久突变体的体液免疫

• 批准号: 9624948
• 负责人: John R. Chan
• 金额: $ 8.94万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE, INC
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-15 至 2018-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9624948
• 关键词: Acid Fast Bacillae Staining Method; Antibodies; Antibody Response; Antigen Targeting; Antigens; Antitubercular Agents; Aspartate; Bacillus (bacterium); Bacteria; Biology; Carbohydrates; Cell Wall; Chronic; Clinical; Collaborations; Cues; Development; Disease; Drug Tolerance; Exposure to; Expression Profiling; Family; Gene Expression; Gene Expression Profile; Goals; Humoral Immunities; Hypoxia; Immune Evasion; Immune response; Immunization; Immunotherapeutic agent; In Vitro; Infection; Inhalation; Joints; Laboratories; Lead; Life Cycle Stages; Link; Lipids; Manuscripts; Masks; Monoclonal Antibodies; Mus; Mycobacterium tuberculosis; Mycobacterium tuberculosis antigens; Mycolic Acid; Organism; Outcome; Pathway interactions; Persons; Phenotype; Phosphorylation; Phosphorylation Site; Physiological; Play; Population; Process; Proteins; Protocols documentation; Publishing; Reagent; Regimen; Research; Role; Starvation; Structure; Surface; Testing; Threonine; Tuberculosis; Tuberculosis Vaccines; Vaccines; base; cell envelope; design; differential expression; holo-(acyl-carrier-protein) synthase; in vivo; interest; macromolecule; macrophage; meetings; mutant; mycobacterial; nitrosative stress; novel; novel strategies; programs; response; tool; tuberculosis immunity; vaccine development; vaccine efficacy

Abstract Mycobacterium tuberculosis (Mtb) is remarkably adept to establishing in an infected host a clinically silent latent state that can subsequently reactivates, posing a formidable hindrance to tuberculosis (TB) control. It is generally thought that the majority of the one-third of the world's population estimated to be infected with Mtb harbor latent bacilli. This latter population affords a large reservoir for the perpetuation of Mtb. The latent persistent form of Mtb is often drug-tolerant and thus difficult to treat. Given the propensity of Mtb to enter dormancy, it is likely that the infectious inoculum inhaled by a susceptible host contains latent form of bacilli in addition to those that are actively replicating. Ample evidence support the notion that Mtb, when exposed to conditions conducive to the establishment of a latent state, displays a gene expression profile distinct from that of actively replicating bacilli. Thus, it is likely that the antigenic profile of a latent persister is different than that of its rapidly growing counterpart. Indeed, loss of acid fastness has been demonstrated in Mtb existing in a chronic persistent state, which is thought to be, at least in part, the result of an aberrant cell envelope structure in dormant bacilli. Based on the above, it stands to reason that an effective TB vaccine should elicit an immune response that can target both actively replicating and latent persistent bacilli. In fact, BCG, the only anti-TB vaccine currently available and generated in conditions unrelated to those conducive to promote persistence (and therefore likely not expressing antigens (Ags) unique to latent tubercle bacilli), may not be capable of inducing an immune response that optimally protects against persistent organisms. The Jacobs group has recently characterized a set of mutants of Mtb kasB, which encodes a -ketoacyl-acyl carrier protein synthase involved in the biosynthetic pathway of mycolic acids (a major family of mycobacterial cell envelope lipids). The study has revealed that KasB activity is regulated via phosphorylation at two threonine residues, and that specific KasB-deficient mutants display phenotypes consistent with features of persisters, including a loss of acid fastness and inability to replicate when inoculated into mice. Importantly, immunization protocol that includes an acid-fast negative kasB persistent mutant -- which phosphorylation sites at the two aforementioned threonine residues have each been replaced by an asaparte (kasB-DD) -- protects against Mtb better than regimens that use BCG alone. The acid-fast negative kasB-DD strain displays an aberrant lipid profile involving species beyond mycolic acids. Aberrant packing of the cell envelope due to abnormal surface lipids such as mycolic acids may expose other macromolecules, including proteins and carbohydraes, that are otherwise masked. Collectively, these observations support the notion that persistent Mtb can express distinct Ags and that targeting such moieties, in addition to those typically present in actively replicating bacilli, might lead to enhanced vaccine efficacy. We therefore hypothesize that targeting Ags differentially expressed by and/or distinct to Mtb persisters represents an effective approach to developing anti- TB strategies including immunotherapeutics and vaccines. To begin testing this hypothesis, we propose to characterize the humoral immune response elicited by the acid-fast negative kasB-DD persister. The choice of this approach is based on emerging evidence suggesting antibodies (Abs) play a significant role in protection against Mtb and in modulating infection outcome. In addition, rigorous characterization of the Ab response to kasB-DD (and in the process, that of the control WT Mtb) can be expected to generate an extensive set of Mtb Ag-specific monoclonal Abs (mAbs) that constitutes a most valuable set of tools for advancing our understanding of three important aspects of Mtb research: (i) the humoral response of WT and persister tubercle bacilli, (ii) the biology of the difficult-to-track persistent Mtb, and (iii) the mechanisms that regulate tuberculous latency. Thus, the information yielded by these studies have the potential to lead to the development of novel strategies for better control of Mtb, including efficacious vaccines.

摘要 结核分枝杆菌（Mtb）非常善于在感染的宿主中建立临床上沉默的 潜伏状态，随后可以重新激活，对结核病（TB）控制构成巨大障碍。是 一般认为，估计世界上三分之一的人口中的大多数感染了结核病 潜伏杆菌这后一种人群为结核分枝杆菌的永久存在提供了一个巨大的储存库。潜 持久性结核病通常是耐药性的，因此难以治疗。 休眠，可能是易感宿主吸入的感染性接种物含有潜伏形式的杆菌， 除了那些正在积极复制的。大量证据支持结核分枝杆菌在暴露于 有利于建立潜伏状态的条件下，显示出不同于 活跃复制的细菌。因此，潜伏持续感染者的抗原谱很可能不同于 快速增长的对手。事实上，已经证明了耐酸性的损失存在于Mtb中， 慢性持续状态，被认为至少部分是异常细胞包膜结构的结果 在休眠的细菌中。基于上述情况，有理由认为有效的结核病疫苗应该引起免疫反应。 可以针对活跃复制和潜伏持久性杆菌的反应。事实上，卡介苗，唯一的抗结核药物 现有疫苗，在与促进持久性无关的条件下生产 (and因此可能不表达潜伏性结核杆菌特有的抗原（Ag）），可能不能 诱导免疫反应，最佳地保护免受持久性生物体的侵害。 雅各布斯小组最近表征了Mtb kasB的一组突变体，该突变体编码β-酮脂酰-酰基 载体蛋白合成酶参与分枝菌酸（分枝杆菌的主要家族）的生物合成途径 细胞包膜脂质）。这项研究表明，KasB活性是通过两个磷酸化来调节的。 苏氨酸残基，并且特异性KasB缺陷突变体显示与 持久性，包括丧失耐酸性和无法复制时，接种到小鼠。重要的是， 免疫方案，包括抗酸阴性kasB持续突变体-其磷酸化位点 在上述两个苏氨酸残基中，每个都被一个单独的（kasB-DD）取代， 比单独使用BCG的方案更好。抗酸阴性kasB-DD菌株显示 涉及分枝菌酸以外的物质的异常脂质谱。细胞包膜的异常包装， 异常的表面脂质如分枝菌酸可暴露其它大分子，包括蛋白质， 碳水化合物，否则会被掩盖。总的来说，这些观察结果支持这样一个概念，即持久化 Mtb可以表达不同的Ag，并且除了那些通常存在于Mtb中的活性部分之外，Mtb还可以靶向这些部分。 复制杆菌，可能会导致增强疫苗的效力。因此，我们假设， 由Mtb持留者差异表达和/或与Mtb持留者不同代表了开发抗- 结核病战略，包括免疫治疗和疫苗。为了开始检验这一假设，我们建议 表征由抗酸阴性kasB-DD持续性引起的体液免疫应答。的选择 这种方法是基于新出现的证据，表明抗体（Ab）在保护中起着重要作用 抗Mtb和调节感染结果。此外，抗体反应的严格表征， kasB-DD（以及在该过程中，对照WT Mtb的）可以预期生成一组广泛的Mtb Ag特异性单克隆抗体（mAb）构成了一组最有价值的工具，用于推进我们的研究。 理解结核分枝杆菌研究的三个重要方面：（i）WT和持久性结核分枝杆菌的体液应答 结核杆菌，（ii）难以追踪的持久性Mtb的生物学，以及（iii）调节 结核潜伏期因此，这些研究产生的信息有可能导致 开发更好地控制结核病的新策略，包括有效的疫苗。