Role of the antiviral ribonuclease, RNase-L, in the host antibacterial response

抗病毒核糖核酸酶 RNase-L 在宿主抗菌反应中的作用

• 批准号: 7737523
• 负责人: BRET A HASSEL
• 金额: $ 37.5万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7737523
• 关键词: Affect; Anti-Bacterial Agents; Antibacterial Response; Antiviral Agents; Bacillus anthracis; Bacteria; Bacterial Infections; Biological; Biological Response Modifiers; Cathepsin E; Elements; Escherichia coli; Exhibits; Foundations; Gene Expression Regulation; Goals; Host Defense; Immune Response Genes; Immune response; Immune system; Immunity; Integration Host Factors; Interferons; Light; Mediating; Mediator of activation protein; Messenger RNA; Microarray Analysis; Molecular; Mus; Neutrophil Infiltration; Pathway interactions; Play; Predisposition; Process; Public Health; RNA Decay; Regulation; Ribonucleases; Role; Signal Pathway; Signal Transduction; Therapeutic; Therapeutic Agents; Trans-Activators; Transcript; Vacuole; Wild Type Mouse; antimicrobial; base; chemokine; combat; cytokine; immune function; mRNA Transcript Degradation; macrophage; mortality; novel; pathogen; public health relevance; response; therapeutic target; therapy development

DESCRIPTION (provided by applicant): Type 1 interferons (IFNs) were discovered as mediators of host antiviral functions, and were recently shown to play essential roles in the innate immune response to nonviral pathogens. Established effectors of IFN antiviral action may thus serve previously unrecognized roles in antibacterial immunity. To understand how IFN exerts its antibacterial activities, the identities and mechanisms of action of specific antibacterial effectors must be determined. Towards this goal, we identified a novel role for RNase-L, an IFN-regulated antiviral ribonuclease, in the host antibacterial response. RNase-L-/- mice exhibited a significant increase in mortality following bacterial challenge. The increased susceptibility of RNase-L-/- mice to bacterial challenge was due to a compromised immune response resulting in an increased bacterial load. Microarray analysis to identify RNase- L-regulated host transcripts that may mediate its antibacterial activity identified two classes of RNase-L- dependent gene regulation that affected transcripts encoding established immune mediators. Specifically, in RNase-L-/- macrophages: 1. basal expression of cathepsin-E (CatE), that mediates endolysosome-associated immune functions, was increased suggesting that this mRNA is an RNase-L substrate; and 2. bacteria-induced expression of proinflammatory cytokines and chemokines was diminished, suggesting that RNase-L indirectly impacts their expression via the modulation of upstream signaling pathway(s). Consistent with the altered CatE expression in RNase-L-/- macrophages, the endolysosome-mediated clearance of phagocytic vacuoles was disrupted following bacterial infection. Bacteria-induced signal transduction was impaired in RNase-L-/- macrophages, providing a mechanistic basis for the diminished cytokine and chemokine expression, and corresponding modulation of neutrophil recruitment. Based on these findings, we hypothesize that RNase-L exerts its antibacterial activity through multiple mechanisms including the regulation of CatE- mediated endolysosome functions, and the induction of host cytokines and chemokines. The goals of this proposal are to dissect the mechanisms by which RNase-L regulates the expression of host immune response genes (aims 1 and 2), and to determine the roles of this regulation in its antibacterial activity (aim 3). The antibacterial activity of RNase-L activators will also be examined. The proposed studies will provide the first information on the role of RNase-L in antibacterial activity, and will identify specific components of RNase-L action as targets for therapeutic modulation of the innate immune response. Public Health Relevance: Bacterial infections are a major public health problem, and the mechanisms by which the immune system combats bacterial infection are incompletely understood. The identification of key mediators of bacterial defense is essential for the development of therapies to enhance the antibacterial immune response. The proposed studies will provide the first information on the role of RNase-L as a novel mediator of antibacterial activity, and will evaluate the antibacterial activity of RNase-L activators as a new class of therapeutic agent.

描述（由申请人提供）：1型干扰素（IFN）被发现是宿主抗病毒功能的介质，最近显示在对非病毒病原体的先天免疫应答中发挥重要作用。因此，已确定的干扰素抗病毒作用效应器可能在抗菌免疫中发挥以前未被认识到的作用。为了了解IFN如何发挥其抗菌活性，必须确定特定抗菌效应物的身份和作用机制。为了实现这一目标，我们确定了RNase-L，干扰素调节的抗病毒核糖核酸酶，在宿主抗菌反应中的新作用。RNase-L-/-小鼠在细菌攻击后表现出死亡率的显著增加。RNase-L-/-小鼠对细菌攻击的易感性增加是由于免疫应答受损导致细菌负荷增加。微阵列分析，以确定RNase-L调节的宿主转录本，可能介导其抗菌活性，确定了两类RNase-L依赖性基因调控，影响转录本编码建立免疫介质。具体地，在RNase-L-/-巨噬细胞中：1.介导内溶酶体相关免疫功能的组织蛋白酶-E（CatE）的基础表达增加，表明该mRNA是RNA酶-L底物;和2.细菌诱导的促炎细胞因子和趋化因子的表达减少，表明RNase-L通过调节上游信号传导途径间接影响它们的表达。与RNase-L-/-巨噬细胞中改变的CatE表达一致，细菌感染后内溶酶体介导的吞噬空泡清除被破坏。RNase-L-/-巨噬细胞中细菌诱导的信号转导受损，为细胞因子和趋化因子表达减少以及中性粒细胞募集的相应调节提供了机制基础。基于这些发现，我们假设RNase-L通过多种机制发挥其抗菌活性，包括调节CatE介导的内溶酶体功能以及诱导宿主细胞因子和趋化因子。本提案的目的是剖析RNase-L调节宿主免疫应答基因表达的机制（目的1和2），并确定这种调节在其抗菌活性中的作用（目的3）。还将检查RNase-L激活剂的抗菌活性。拟议的研究将提供关于RNase-L在抗菌活性中的作用的第一个信息，并将确定RNase-L作用的特定组分作为先天免疫应答的治疗调节的靶点。公共卫生相关性：细菌感染是一个主要的公共卫生问题，免疫系统对抗细菌感染的机制还不完全清楚。鉴定细菌防御的关键介质对于开发增强抗菌免疫应答的疗法至关重要。拟议的研究将提供关于RNase-L作为抗菌活性的新型介体的作用的第一信息，并将评估RNase-L激活剂作为新型治疗剂的抗菌活性。