Exploiting a cyclic dinucleotide-mediated immune response to reduce the burden of Coxiella burnetii infection

项目摘要/摘要： 环二核苷酸(CDN)在革兰氏阴性菌中起着重要的第二信使作用， 调节许多不同类型的细菌过程，如运动性、生物膜形成、宿主 定居、细菌生长和新陈代谢。CDN水平受细菌编码的严密控制 二鸟苷/二腺苷环化酶和磷酸二酯酶。除了调节细菌的生命周期 在感染过程中，CDN可以提醒先天免疫反应。一种主要的细胞质传感器，用于 动物宿主的细胞内CDN是刺痛的，一旦被激活，就会触发先天免疫反应 通过I型干扰素和促炎细胞因子的诱导。因此，合成CDN已经被 感染前外用，刺激炎性小体活动，减轻衣原体载量 沙眼衣原体是一种革兰氏阴性的专性胞内细菌。因此，CDN可以用来启动免疫 除了标准的两周抗生素治疗外，对治疗衣原体感染的反应。 另一种革兰氏阴性、专性细胞内、嗜巨噬细胞的细菌是伯氏柯克斯体，它 是人畜共患病Q热的病原体。柯克斯体的主要传播途径是通过 气雾剂。然而，柯克斯氏菌也在扁虱中发现，它们被认为是媒介。急性期 这种疾病在人类中主要以流感样症状为特征，个人发展为 慢性感染必须接受18-24个月的抗生素治疗。我们认为，替代方法是 目前需要开发抗生素治疗方法，以减少受感染动物的柯克斯氏菌载量。我们的预赛 数据表明，CDN是在柯克斯体感染期间产生的，并且柯克斯体基因组包含 编码二鸟苷/双腺苷环化酶和磷酸二酯酶的可能基因。然而，人们对此知之甚少 关于CDN如何在柯克斯体感染期间引起刺痛介导的宿主反应。因此，我们建议 确定CDN如何控制对伯氏柯克斯体感染的先天免疫反应。在目标1中，我们将 描述脊椎动物和无脊椎动物模型中针刺介导的宿主对柯克斯氏菌感染的反应。在……里面 目的2，我们将剖析刺痛在柯克斯体感染过程中对caspase激活的作用机制 以及程序性细胞死亡。在目标3中，我们将用CDN刺激宿主的先天免疫反应 脊椎动物和无脊椎动物模型，以减少柯克斯体感染的幅度。 总之，拟议的工作将描述CDN介导的针对柯克斯体的先天性免疫反应。 感染，以及我们如何利用CDNS来减少总体柯克斯体负担。无脊椎动物模型的使用 柯克斯体感染可能也适用于其他媒介传播的疾病。从这项研究中获得的信息将 对治疗柯克斯病的新疗法的开发具有广泛的先天免疫影响 感染，我们将确定潜在的CDN/STING介导的免疫机制，这将是 适用于其他病原性感染。

Project Summary/Abstract: Cyclic dinucleotides (CDNs) play important second messenger roles in Gram-negative bacteria, regulating a number of different types of bacterial processes such as motility, biofilm formation, host colonization, bacterial growth, and metabolism. CDNs levels are tightly controlled by bacterial encoded diguanylate/diadenylate cyclases and phosphodiesterases. In addition to regulating bacterial life cycle processes, CDNs can alert the innate immune response during infection. A major cytosolic sensor for intracellular CDNs in animal hosts is STING, which upon its activation, triggers an innate immune response through the induction of type I interferon and pro-inflammatory cytokines. As such, synthetic CDNs have been applied exogenously prior to infection to stimulate inflammasome activity and reduce the load of Chlamydia trachomatis, a Gram-negative, obligate intracellular bacterium. Thus CDNs can be used to initiate an immune response to therapeutically treat Chlamydia infection, in addition to standard two-week antibiotic therapy. Another Gram-negative, obligate intracellular, macrophage-tropic bacterium is Coxiella burnetii, which is the causative agent of the zoonotic disease Q fever. The primary route of Coxiella transmission is through aerosols. However, Coxiella is also found in ticks, and they have been implicated as vectors. Acute phase of the disease in humans is characterized primarily by influenza-like symptoms, and individuals that develop chronic infection must undergo 18-24 months of antibiotic therapy. We contend that alternative methods to current antibiotic treatments need to be developed to reduce Coxiella load in infected animals. Our preliminary data suggests that CDNs are produced during Coxiella infection and that the Coxiella genome contains putative genes that encode diguanylate/diadenylate cyclases and phosphodiesterases. However, little is known about how CDNs elicit a STING-mediated host response during Coxiella infection. Thus, we propose to determine how CDNs control the innate immune response to Coxiella burnetii infection. In Aim 1, we will characterize the STING-mediated host response to Coxiella infection in vertebrate and invertebrate models. In Aim 2, we will dissect STING's mechanism of action during Coxiella infection with regard to caspase activation and programmed cell death. In Aim 3, we will stimulate the host innate immune response with CDNs in vertebrate and invertebrate models to reduce the magnitude of Coxiella infection. Together, the proposed work will characterize the CDN-mediated innate immune response to Coxiella infection and how we can exploit CDNs to reduce overall Coxiella burden. The use of invertebrate models of Coxiella infection may be applicable to other vector-borne diseases. The information gained in this study will have broad-ranging impacts in innate immunity towards to the development of new therapies to treat Coxiella infection, and we will identify potentially novel CDN/STING-mediated mechanisms of immunity that will be applicable to other pathogenic infections.