Oxysterol Regulation of Microbial Pathogenesis

项目摘要 拟议的项目集中在我们最近的发现，即免疫产生的氧固醇25- 羟基胆固醇(25HC)有效地抑制两种全球重要细菌的细胞传播 病原菌、单核细胞增多性李斯特菌和福氏志贺氏菌。25HC的抗菌活性是通过介导的 通过从质膜(PM)动员可访问的胆固醇池。可及 胆固醇是PM胆固醇细分的三个池之一，这个池调节细胞 控制脂质动态平衡和细胞生长的信号通路。通过首先对分子进行表征 25HC诱导可及胆固醇内化的机制(目标1)，这些研究将揭示 胆固醇是如何在细胞因子刺激下快速转运的。第二，我们将确定如何 PM胆固醇的重塑抑制李斯特菌和志贺氏菌穿透细胞间的接触 粘膜上皮连接(目标2)。这项工作将揭示哺乳动物是如何增强屏障功能的 通过胆固醇代谢途径对粘膜表面的影响，并将确定在 可能被众多微生物病原体利用的粘膜免疫系统。第三，我们将发展新的 监测生物体内胆固醇动态的技术，并利用这些技术 确定在细菌感染时调动可获得的胆固醇的组织和细胞类型(目标 3)。最后，氧固醇介导的免疫途径的生理学意义将在 哺乳动物模型生物使用三个互补的小鼠模型来扰乱25HC的激活， 生产和下游活动(目标4)。从这些研究中收集到的见解，从基础研究到 生物化学对小鼠的感染模型，将解释人类免疫系统如何适应 保护屏障细胞免受细胞内细菌感染的胆固醇代谢的基本方面。 开发模仿本提案中确定的25HC分子活性的新药将是 抗击与利用宿主的病原体相关的人类传染病的创新方法 胆固醇代谢。这些研究还将为研究急性胰腺炎的发病机制提供新的见解。 重要的传染病致病因子，也可进入人体的生物学炎症反应。

Project Summary The proposed project focuses on our recent discovery that immunological production of the oxysterol 25- Hydroxycholesterol (25HC) potently inhibits the cellular dissemination of two globally important bacterial pathogens, Listeria monocytogenes and Shigella flexneri. The anti-bacterial activity of 25HC is mediated through mobilization of the accessible cholesterol pool from the plasma membrane (PM). Accessible cholesterol is one of three pools into which PM cholesterol is sub-divided and this pool regulates cellular signaling pathways that control lipid homeostasis and cell growth. By first characterizing the molecular mechanism by which 25HC induces internalization of accessible cholesterol (Aim 1), these studies will reveal how cholesterol can be rapidly transported in response to cytokine stimulation. Second, we will determine how remodeling of PM cholesterol suppresses Listeria and Shigella from penetrating the cell-to-cell contact junctions of the mucosal epithelium (Aim 2). This work will reveal how mammals enhance the barrier function of mucosal surfaces through cholesterol metabolic pathways and will identify points of weakness in the mucosal immune system that may be exploited by numerous microbial pathogens. Third, we will develop new technologies for monitoring cholesterol dynamics in the living organism and use these technologies to determine the tissues and cell types that mobilize accessible cholesterol in response to bacterial infection (Aim 3). Finally, the physiological significance of oxysterol-mediated immune pathways will be investigated in mammalian model organisms using three complementary mouse models that disrupt 25HC activation, production, and downstream activity (Aim 4). Insights gleaned from these studies, which range from basic biochemistry to mouse models of infection, will explain how the human immune system has adapted fundamental aspects of cholesterol metabolism to protect barrier cells from intracellular bacterial infection. Developing new drugs that mimic the molecular activity of 25HC as determined in this proposal would be an innovative approach to combat human infectious disease associated with pathogens that exploit host cholesterol metabolism. These studies will also provide new insights into the pathogenic mechanisms of an important infectious disease-causing agent and also into the biology of the human inflammatory response.