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.

抽象的 结核分枝杆菌 (Mtb) 异常善于在受感染宿主体内建立临床沉默状态 潜伏状态随后可能重新激活，对结核病（TB）控制构成巨大障碍。 人们普遍认为，估计世界上三分之一人口中的大多数都感染了 Mtb 后一种群体为结核菌的长期存在提供了一个巨大的储存库。 持久性结核分枝杆菌通常具有耐药性，因此鉴于结核分枝杆菌的侵入倾向而难以治疗。 休眠期，易感宿主吸入的传染性接种物很可能含有潜伏形式的杆菌 除了那些正在积极复制的病毒之外，还有大量证据支持 Mtb 在接触时的观点。 有利于建立潜伏状态的条件，显示出与潜伏状态不同的基因表达谱 因此，潜在存留菌的抗原谱可能与此不同。 事实上，已证明存在于 Mtb 中的耐酸牢度丧失。 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 根据上述情况，有效的结核疫苗应该能引发免疫。 事实上，卡介苗是唯一的抗结核药物。 目前可用的疫苗和在与有利于促进持久性无关的条件下产生的疫苗 （因此可能不表达潜伏结核杆菌特有的抗原（Ag）），可能无法 诱导免疫反应，最佳地防御持久性微生物。 Jacobs 小组最近鉴定了 Mtb kasB 的一组突变体，该突变体编码 -酮酰基-酰基 载体蛋白合酶参与分枝杆菌酸（分枝杆菌酸的一个主要家族）的生物合成途径 研究表明，KasB 活性通过两个位点的磷酸化进行调节。 苏氨酸残基，并且特定的 KasB 缺陷突变体表现出与特征一致的表型 持续存在，包括接种到小鼠体内时失去耐酸牢度和无法复制。 免疫方案包括抗酸阴性 kasB 持久突变体——其磷酸化位点 上述两个苏氨酸残基均被天冬氨酸 (kasB-DD) 取代——保护 抗酸阴性 kasB-DD 菌株对 Mtb 的抵抗力优于单独使用 BCG 的方案。 异常的脂质谱涉及分枝菌酸以外的物种由于细胞包膜的异常堆积。 异常的表面脂质（例如霉菌酸）可能会暴露其他大分子，包括蛋白质和 总的来说，这些观察结果支持了持久性的观点。 Mtb 可以表达不同的 Ag，并且除了那些通常存在于活性物质中的抗原之外，还可以表达靶向这些部分的抗原。 因此，我们捕获了针对 Ag 的疫苗功效。 Mtb 持续者的差异表达和/或独特代表了开发抗结核菌的有效方法。 结核病策略包括免疫治疗和疫苗。为了开始检验这一假设，我们建议： 表征抗酸阴性 kasB-DD 持续者引起的体液免疫反应。 该方法基于新出现的证据，表明抗体 (Abs) 在保护中发挥重要作用 此外，严格表征抗体对 Mtb 的反应。 kasB-DD（以及在此过程中，控制 WT Mtb 的过程）预计会生成一组广泛的 Mtb Ag 特异性单克隆抗体 (mAb) 构成了一套最有价值的工具，可促进我们的发展 了解 Mtb 研究的三个重要方面：(i) WT 和持续者的体液反应 结核杆菌，(ii) 难以追踪的持久性结核分枝杆菌的生物学，以及 (iii) 调节机制 因此，这些研究产生的信息有可能导致结核潜伏期。 制定更好地控制结核分枝杆菌的新策略，包括有效的疫苗。