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: 9888303
• 负责人: Matthew D Welch
• 金额: $ 23.55万
• 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/9888303
• 关键词: Animal Model; Anti-Bacterial Agents; Antiviral Agents; Bacteria; Binding Proteins; Biological; Bone Marrow; C57BL/6 Mouse; Candidate Disease Gene; Cells; Chromosome 3; Data; Dermal; Development; Diagnosis; Disease; Endothelial Cells; Exhibits; 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; Rickettsia parkeri; 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; spotted fever; 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.

项目概要/摘要 立克次体是一组不同的革兰氏阴性、专性细胞内细菌病原体，可引起 人类疾病，包括斑疹伤寒和斑疹热。斑疹热群的病原体之一 (SFG) 美国立克次体病，帕克里立克次体已被证明是一种独特且强大的研究模型 在细胞水平上具有致病性，因为它会引起非致命性焦痂相关疾病，因此可以 在生物安全2级条件下生长，有利于细胞生物学研究。然而，进展 开发 R. Parkeri 作为研究对 SFG 立克次体感染的先天免疫反应的模型 由于缺乏使用突变小鼠的研究而受到阻碍。因此，关于先天性的关键问题 对 SFG 立克次体的免疫反应仍未得到解答，包括细菌如何对 I 型反应 干扰素（IFN-I），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) 受体的小鼠被帕克里氏菌皮内感染 导致感染部位出现坏死性病变并偶尔致死，而缺乏每个个体的小鼠 受体没有表现出任何症状。这证明了 IFN-I（和 IFN-g）在限制 R. parkeri 生长方面的作用。 体内。此外，双突变体的病理学类似于（但更严重）发生在 人类感染，表明它可能代表人类疾病的新动物模型。我们还观察到 IFN-I 严重限制原代小鼠巨噬细胞中帕克里氏菌的生长，部分原因是 IFN-I 调节的基因产物（包括抗菌鸟苷酸结合蛋白 (GBP)）具有杀伤作用。尽管 尽管取得了这些进展，但仍然存在两个关键的知识空白：（1）尚不清楚 IFN-I 如何限制 R. parkeri 的生长 在体内器官/组织/细胞水平； (2)尚不清楚 IFN-I 上调的基因产物如何杀死 R. Parkeri 在细胞/分子水平上。我们假设 IFN-I 在限制 立克次体通过胞质抗菌分子的上调在体内和体外生长。我们将测试这个 假设有两个目标。在目标 1 中，我们将描述静脉内和皮内感染的动力学， 由此产生的器官和组织病理学，以及缺乏这两种受体的小鼠中被帕克里氏菌感染的细胞类型 对于 IFN-I/IFN-g。这些研究将揭示 IFN-I 如何限制 R. parkeri 在体内的生长，并将建立一个 用于研究 SFG 立克次体发病机制的稳健小鼠模型。在目标2中，我们将测试效果 激活或突变候选抗菌因子（通过 RNAseq 鉴定）以杀死下游的细菌 IFN-I 信号传导，并将测试 GBP 是否限制体外内皮细胞和小鼠体内的 R. parkeri 生长。 体内。我们的研究结果将揭示 IFN-I 如何在体外限制 R. parkeri 以及其他微生物的生长 和体内。此外，我们将开发一种新的动物模型来研究帕克里氏菌的发病机制。