Modulating Nrf2-Reguated GSH Production to Prevent Hospital-Acquired Infections

调节 Nrf2 调节的 GSH 产生以预防医院获得性感染

基本信息

批准号：
8777761
负责人：
Yusen Liu
金额：
$ 18.61万
依托单位：
RESEARCH INST NATIONWIDE CHILDREN'S HOSP
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-06-01 至 2016-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8777761
关键词：
Accounting Animals Anti-Bacterial Agents Antioxidants Bacteremia Bacteria Bacterial Infections Blood Blood Circulation Bone Marrow Catalytic Domain Cessation of life Critical Illness Cytosol Death Rate Defect Development Embryo Enzymes Escherichia coli Exhibits Failure Functional disorder Genes Glutamate-Cysteine Ligase Glutathione Glutathione Disulfide Glutathione Reductase Goals Health system Histology Hospitals Host Defense Immune Immunity Immunosuppression In Vitro Infection Inflammation Inflammatory Response Intensive Care Units Investigation Knock-out Knockout Mice Laboratories Lead Leukocytes Ligase LoxP-flanked allele Mediating Morbidity - disease rate Multi-Drug Resistance Mus Mutant Strains Mice Myelogenous Natural regeneration Nosocomial Infections Organ Organism Outcome Oxidative Stress Pathway interactions Patients Phagocytosis Pharmaceutical Preparations Pneumonia Pre-Clinical Model Predisposition Prevention Process Production Prophylactic treatment Reduced Glutathione Regulation Respiratory Burst Role Staphylococcus aureus Streptococcus Group B System Testing Therapeutic Urinary tract infection Ventilator animal mortality bactericide cost cytokine efficacy testing fighting improved in vivo killings mortality neonatal sepsis neutrophil novel therapeutic intervention novel therapeutics oxidative damage pathogen prevent public health relevance recombinase response transcription factor

项目摘要

DESCRIPTION (provided by applicant): Hospital-acquired infections are a major cause of mortality and morbidity in intensive care units, and critically ill patients are particularly susceptible to bacterial infections due to immunosuppression. Since an increasingly greater portion of the hospital-acquired infections are caused by multidrug-resistant organisms, new therapeutic approaches are needed to prevent and treat bacterial infections in intensive care units. Our long- term goal is to develop an effective therapeutic strategy to overcome immunosuppression in critically ill patients through bolstering the bactericidal activity of neutrophils. Critically ill patients often display increased oxidative stress and have decreased levels of glutathione (GSH), a major intracellular antioxidant. GSH is generated through two pathways: de novo synthesis and regeneration from oxidized glutathione (GSSG). Recent studies in our laboratory demonstrated that mice lacking glutathione reductase (Gsr), which catalyzes GSH regeneration from GSSG, are highly vulnerable to infection by several bacterial species associated with hospital-acquired infections, as indicated by high rates of death, severe organ damage, and enhanced inflammation. The underlying cause of the increased vulnerability to bacterial infection is the failure to kill the infecting organism. In the absence of Gsr, neutrophils, the primary white blood cells responsible for bacterial eradication, cannot efficientl ingest and kill the infecting bacteria, likely due to excessive oxidative damage to the neutrophils themselves. Our studies indicate that GSH regeneration is pivotal for neutrophil-mediated host defense, raising the intriguing question of whether excessive oxidative stress is itself responsible for the immunosuppression seen in critically ill patients. Our findings strongly suggest that de novo GSH synthesis will be crucial for an effective immune defense against bacterial pathogens, since Gsr activity depends on de novo GSH synthesis, i.e. without GSH there can be no GSSG. The rate-limiting step in de novo GSH synthesis is glutamate-cysteine ligase, which consists of a catalytic subunit (Gclc) and a modulatory subunit (Gclm). The transcription factor Nrf2 regulates the expression of Gsr, Gclm, and Gclc, and thus Nrf2 modulates both de novo GSH synthesis and GSH regeneration from GSSG. The central hypothesis of our proposal is that the GSH antioxidant system modulated by Nrf2 facilitates host defense by maintaining bactericidal activity in neutrophils. The objectives of this proposal are to determine the role of GSH in neutrophil-mediated host defense and to assess the efficacy of Nrf2 activation as an approach to enhance host defense. The specific aims of this R21 proposal are to define the functions of the two GSH-generating pathways in anti-bacterial immune defense (Aim 1), and to evaluate the efficacy of Nrf2 activation as a therapeutic strategy to bolster neutrophil bactericidal activity (Aim 2). Our studies will elucidate a potential mechanism underlying immunosuppression in critically ill patients. Our studies will also facilitate the development of novel therapeutic drugs for the prevention and treatment of hospital-acquired infections in intensive care units.

描述（由申请人提供）：医院获得的感染是重症监护病房死亡率和发病率的主要原因，重症患者因免疫抑制引起的细菌感染特别容易受到细菌感染的影响。由于越来越多的医院获得感染是由多种耐药的生物引起的，因此需要新的治疗方法来预防和治疗重症监护病房中的细菌感染。我们的长期目标是制定一种有效的治疗策略，通过增强嗜中性粒细胞的杀菌活性来克服重症患者的免疫抑制。重症患者经常表现出增加的氧化应激，并降低了细胞内抗氧化剂的谷胱甘肽（GSH）水平。 GSH是通过两种途径生成的：从头合成和氧化谷胱甘肽（GSSG）的再生。在我们的实验室中的最新研究表明，缺乏谷胱甘肽还原酶（GSR）的小鼠催化GSSG的GSH再生，高度容易受到与医院获得的感染相关的几种细菌感染，这取决于高死亡率，严重的器官损伤和增强的炎症。造成细菌感染脆弱性增加的根本原因是未能杀死感染生物体。在没有GSR的情况下，中性粒细胞是负责细菌根除的主要白细胞，无法有效摄入并杀死感染细菌，这可能是由于对中性粒细胞的氧化损害过多自己。我们的研究表明，GSH再生对于中性粒细胞介导的宿主防御至关重要，这提出了一个有趣的问题，即过度氧化应激本身是否造成了重症患者中的免疫抑制。我们的发现强烈表明，从头gsh的合成对于针对细菌病原体的有效免疫防御至关重要，因为GSR活性取决于从头GSH的合成，即没有GSH，就没有GSSG。从头GSH合成的速率限制步骤是谷氨酸 - 半胱氨酸连接酶，它由催化亚基（GCLC）和调节亚基（GCLM）组成。转录因子NRF2调节GSR，GCLM和GCLC的表达，因此NRF2调节GSSG的从头gsh合成和GSH再生。我们建议的中心假设是，NRF2调节的GSH抗氧化剂系统通过维持中性粒细胞中的杀菌活性来促进宿主防御。该提议的目标是确定GSH在中性粒细胞介导的宿主防御中的作用，并评估NRF2激活作为增强宿主防御的一种方法。该R21提案的具体目的是将两种GSH生成途径的功能定义在抗细菌免疫防御中（AIM 1），并评估NRF2激活作为增强中性粒细胞粒细胞活性的治疗策略的功效（AIM 2）。我们的研究将阐明重症患者免疫抑制的潜在机制。我们的研究还将促进新型治疗药物的开发，以预防和治疗重症监护病房的医院获得感染。