Exploring the role of type I interferon in Rickettsia pathogenesis

探讨I型干扰素在立克次体发病机制中的作用

• 批准号: 9764949
• 负责人: Matthew D Welch
• 金额: $ 19.63万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-03-06 至 2021-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9764949
• 关键词: Animal Model; Anti-Bacterial Agents; Antiviral Agents; Bacteria; Binding Proteins; Biological; Bone Marrow; C57BL/6 Mouse; Candidate Disease Gene; Cells; Chromosomes, Human, Pair 3; Data; Dermal; Development; Diagnosis; Disease; Endothelial Cells; Exhibits; Fever; Genes; Growth; Human; Immune response; Immune signaling; In Vitro; Individual; Infection; Innate Immune Response; Innate Immune System; Interferon Gamma Receptor Complex; Interferon Type I; Interferon Type II; Interferons; Intravenous; Kinetics; Knock-out; Knowledge; Lead; Lesion; Microbe; Molecular; Mus; Mutant Strains Mice; Mutate; Necrotic Lesion; Organ; Pathogenesis; Pathogenicity; Pathology; Pathway interactions; Play; Resistance; Rickettsia; Rickettsia Infections; Role; Signal Pathway; Signal Transduction; Site; Study models; Symptoms; Testing; Time; Tissues; Transgenic Organisms; Typhus; Up-Regulation; Wild Type Mouse; Work; antimicrobial; cell type; cytokine; experimental study; gene product; guanylate; human disease; human model; in vivo; macrophage; mouse model; mutant; novel strategies; pathogen; pathogenic bacteria; receptor; response; tool; transcription factor; transcriptome sequencing

PROJECT SUMMARY / ABSTRACT The Rickettsiae are a diverse group of Gram-negative, obligate intracellular bacterial pathogens that cause human diseases, including typhus and spotted fever. Among the causative agents of spotted fever group (SFG) rickettsiosis in the U.S., Rickettsia parkeri has proven to be a uniquely powerful model for studying pathogenicity at the cellular level, because it causes a non-lethal eschar-associated disease and therefore can be grown under biosafety level 2 conditions, facilitating cell biological studies. However, progress toward developing R. parkeri as a model for studying the innate immune response to SFG Rickettsia infection has been hindered by a dearth of studies employing mutant mice. As such, key questions regarding the innate immune response to SFG Rickettsia remain unanswered, including how the bacteria respond to type I interferon (IFN-I), an important cytokine of the innate immune system. Our new preliminary data indicate that intradermal infection of mice lacking both receptors for IFN-I and type II interferon (IFN-g) with R. parkeri results in a necrotic lesion at the site of infection and occasional lethality, whereas mice lacking each individual receptor exhibit no symptoms. This demonstrates a role for IFN-I (and IFN-g) in restricting R. parkeri growth in vivo. Moreover, the pathology of the double mutant is similar to (but more severe than) that occurring during human infection, suggesting it may represent a new animal model of human disease. We have also observed that IFN-I severely restricts R. parkeri growth in primary mouse macrophages, and that this is partially due to killing by the IFN-I regulated gene products, including antimicrobial guanylate binding proteins (GBPs). Despite these advances, there remain two key gaps in knowledge: (1) it is unclear how IFN-I restricts R. parkeri growth at the organ/tissue/cellular level in vivo; and (2) it is not known how gene products upregulated by IFN-I kill R. parkeri at the cellular/molecular level. We hypothesize that that IFN-I plays an important role in restricting Rickettsia growth in vivo and in vitro via the upregulation of cytosolic antibacterial molecules. We will test this hypothesis in two aims. In Aim 1, we will characterize the kinetics of intravenous and intradermal infection, the resulting organ and tissue pathologies, and the cell types infected by R. parkeri in mice lacking both receptors for IFN-I/IFN-g. These studies will reveal how IFN-I restricts growth of R. parkeri in vivo and will establish a robust murine model for investigating SFG Rickettsia pathogenesis. In Aim 2, we will test the effect of activating or mutating candidate antimicrobial factors (identified by RNAseq) on bacterial killing downstream of IFN-I signaling, and will test whether the GBPs restrict R. parkeri growth in endothelial cells in vitro and mice in vivo. Our findings will reveal how IFN-I restricts the growth of R. parkeri, and perhaps other microbes, in vitro and in vivo. Furthermore, we will develop a new animal model to investigate R. parkeri pathogenesis.

项目摘要 /摘要 立克人士是一组多样的革兰氏阴性，强制性细胞内细菌病原体，引起 人类疾病，包括斑疹伤寒和斑点发烧。在斑点发烧组的病因中 （SFG）立克的立克人士，Rickettsia Parkeri已被证明是一个独特的强大模型 在细胞水平上的致病性，因为它会导致非致命的eSchar相关疾病，因此可以 在生物安全2级条件下生长，促进细胞生物学研究。但是，进步 开发R. parkeri是研究对SFG立克感染的先天免疫反应的模型 通过使用突变小鼠的研究所阻碍。因此，有关先天的关键问题 对SFG人力车的免疫反应仍未得到解答，包括细菌对I型的反应 干扰素（IFN-I），这是先天免疫系统的重要细胞因子。我们的新初步数据表明 缺乏IFN-I和II型干扰素（IFN-G）的小鼠的皮内感染（IFN-G） 导致感染部位和偶尔致死性的坏死病变，而小鼠缺乏每个人 受体没有症状。这证明了IFN-I（和IFN-G）在限制R. parkeri增长中的作用 体内。此外，双重突变体的病理类似于（但比在 人类感染，表明它可能代表了人类疾病的新动物模型。我们也观察到 IFN-i严重限制了原发性小鼠巨噬细胞中的帕克里（R. parkeri）的生长，这部分是由于 IFN-I调控基因产物杀死，包括抗菌鸟苷结合蛋白（GBP）。尽管 这些进步，知识的关键差距还有两个关键差距：（1）尚不清楚IFN-I如何限制R. Parkeri的增长 在体内器官/组织/细胞水平； （2）尚不清楚基因产物如何被IFN-I杀死R。 Parkeri在细胞/分子水平上。我们假设IFN-I在限制中起着重要作用 人体体内和体外的生长通过胞质抗菌分子的上调。我们将测试这个 两个目标的假设。在AIM 1中，我们将表征静脉内和皮内感染的动力学，即 由此产生的器官和组织病理，以及缺乏两个受体的小鼠感染的细胞类型 对于IFN-I/IFN-G。这些研究将揭示IFN-I如何限制体内帕克里的生长，并将建立一个 强大的鼠模型用于研究SFG人力素的发病机理。在AIM 2中，我们将测试 激活或突变候选抗菌因子（由RNASEQ鉴定）在细菌杀死下游 IFN-I信号传导，并将测试Gbps是否在体外和小鼠中限制内皮细胞中的R. parkeri生长 体内。我们的发现将揭示IFN-I如何限制R. parkeri的生长，甚至是其他微生物的体外 和体内。此外，我们将开发一种新的动物模型来研究R. parkeri发病机理。