Prevention of oxidative stress decreases persistence of drug tolerant M. Tubercu

预防氧化应激可降低耐药结核分枝杆菌的持久性

• 批准号: 7897739
• 负责人: Randall J Basaraba
• 金额: $ 18.7万
• 依托单位: COLORADO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-22 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7897739
• 关键词: Address; Adverse effects; Animals; Antibiotics; Antioxidants; Antitubercular Agents; Bacillus (bacterium); Bacteria; Bacterial Infections; Cause of Death; Cavia; Cell Nucleus; Combination Drug Therapy; Complex; Cytoplasm; Data; Development; Drug Combinations; Drug Tolerance; Effectiveness; Epidemic; Extreme drug resistant tuberculosis; Face; Goals; Grant; Host Defense; Human; Immune response; Infection; Infection Control; Length; Lesion; Lung; Lung Inflammation; Mediating; Microscopic; Modeling; Mycobacterium tuberculosis; Necrosis; Necrotic Lesion; Nuclear; Oxidation-Reduction; Oxidative Stress; Pathogenesis; Patients; Pharmaceutical Preparations; Pharmacotherapy; Play; Population; Prevention; Primary Lesion; Proteins; Research; Role; Staging; Structure of parenchyma of lung; Testing; Therapeutic; Time; Tissues; Tuberculosis; antimicrobial drug; antioxidant therapy; bactericide; base; burden of illness; cost; design; fight against; fighting; human tissue; in vivo; killings; macrophage; neutrophil; novel; novel strategies; pathogen; prevent; public health relevance; resistant strain; transcription factor; treatment duration; treatment strategy; tuberculosis drugs; tuberculosis treatment

DESCRIPTION (provided by applicant): In the early stages of Mycobacterium tuberculosis (Mtb) infection, irreversible tissue necrosis occurs as the result of localized lung inflammation. The bactericidal mechanism of macrophages and neutrophils, that are supposed to control the infection, in fact cause lung tissue damage and thus create a microenvironment that favors Mtb persistence. While Mtb is primarily an intra- cellular pathogen, we and others have shown that drug-tolerant bacilli can persist extra- cellularly in lesions with necrosis. Our long term goals is to determine whether restoring antioxidant capacity therapeutically will prevent the establishment of persistent, drug-tolerant bacilli thus rendering conventional anti-tuberculosis therapy more effective in animals and humans. Central to our proposal is the use of experimental Mtb infections in guinea pigs which develop primary lesion necrosis similar to humans with naturally occurring tuberculosis. Our hypothesis is that by restoring therapeutically the antioxidant defenses regulated by the host transcription factor nuclear redox factor2 (Nrf2) in Mtb-infected guinea pigs, conventional anti-tuberculosis drug therapy will be more effective against persistent, drug-tolerant bacilli. Our preliminary data shows that oxidative stress exists in human and guinea pig Mtb lesions. These lesions have excessive oxidative stress that depletes systemic and pulmonary antioxidant defenses. Oxidative defenses in the host are regulated, in part, by the transcription factor Nrf2. In human and guinea pig Mtb lesions, Nrf2 is defective since it fails to translocate from the cytoplasm to the nucleus. As a result, other downstream antioxidant proteins are not expressed in lesions. The aim of this grant is to: Resolve whether Nrf2 targeted antioxidant therapy will increase the efficacy of anti-tuberculosis drugs. We will accomplish this aim by (1) further defining the role of oxidative stress and the depletion of Nrf2- regulated antioxidant defenses in the pathogenesis of lesion necrosis and Mtb persistence, (2) determining whether antioxidant drugs can restore Nrf2-regulated endogenous antioxidant defenses and (3), determining whether Nrf2 inducing drugs can be used to enhance the effectiveness of current anti-tuberculosis drugs by eliminating the persistence of drug-tolerant bacilli. By better understanding the pathogenesis of Mtb persistence and drug-tolerance, new treatment strategies can be added to the global fight to control human tuberculosis. PUBLIC HEALTH RELEVANCE: As the body fights the bacterium that causes human tuberculosis, permanent tissue damage occurs, which allows the bacterium to hide and avoid being killed by antimicrobial drugs. Our research is aimed at preventing tissue damage and bacterial persistence so that antibiotics are more effective and the length of time required for patient treatment is reduced.

描述（申请人提供）：在结核分枝杆菌（Mtb）感染的早期阶段，由于局部肺部炎症而发生不可逆的组织坏死。巨噬细胞和中性粒细胞的杀菌机制本应控制感染，但实际上会造成肺组织损伤，从而创造一个有利于结核分枝杆菌持续存在的微环境。虽然结核分枝杆菌主要是一种细胞内病原体，但我们和其他人已经证明，耐药杆菌可以在坏死病变的细胞外持续存在。我们的长期目标是确定通过治疗恢复抗氧化能力是否会阻止持久性耐药杆菌的形成，从而使传统的抗结核治疗对动物和人类更有效。我们建议的核心是在豚鼠中使用实验性结核分枝杆菌感染，豚鼠会出现类似于人类自然发生结核病的原发性病变坏死。我们的假设是，通过在治疗上恢复受结核分枝杆菌感染的豚鼠宿主转录因子核氧化还原因子2 (Nrf2) 调节的抗氧化防御，传统的抗结核药物治疗将更有效地对抗持久性耐药杆菌。我们的初步数据表明，人类和豚鼠结核分枝杆菌病变中存在氧化应激。这些病变具有过度的氧化应激，会耗尽全身和肺部的抗氧化防御能力。宿主的氧化防御部分受到转录因子 Nrf2 的调节。在人和豚鼠 Mtb 病变中，Nrf2 有缺陷，因为它无法从细胞质易位到细胞核。因此，其他下游抗氧化蛋白在病变中不表达。这笔资助的目的是：解决Nrf2靶向抗氧化疗法是否会提高抗结核药物的疗效。我们将通过以下方式实现这一目标：（1）进一步明确氧化应激和 Nrf2 调节的抗氧化防御的耗竭在病灶坏死和 Mtb 持久性发病机制中的作用，（2）确定抗氧化药物是否可以恢复 Nrf2 调节的内源性抗氧化防御(3)确定Nrf2诱导药物是否可以通过消除耐药杆菌的持续存在来增强现有抗结核药物的有效性。通过更好地了解结核分枝杆菌持久性和耐药性的发病机制，可以为全球控制人类结核病的斗争添加新的治疗策略。公共健康相关性：当人体与引起人类结核病的细菌作斗争时，会发生永久性组织损伤，从而使细菌隐藏起来并避免被抗菌药物杀死。我们的研究旨在防止组织损伤和细菌持续存在，从而使抗生素更加有效并缩短患者治疗所需的时间。