Dissection of Shigella pathogenesis in vivo using a new oral infection mouse model

项目概要/摘要 志贺氏菌是人类高度传染性的重要病原体。 2016年，有一个 据估计，志贺氏菌感染人数为 2.69 亿，死亡人数为 212,000 人。人类通常感染 口服摄入最少的接种物（仅含 10-100 个细菌）后的志贺氏菌。一个专业 志贺氏菌研究的障碍是缺乏能够概括关键的体内口腔感染小鼠模型 人类疾病的各个方面。小鼠对口服志贺氏菌的抵抗力高达 1 亿个细菌，但原因 对于这种抵抗仍然知之甚少。在我们的初步数据中，我们描述了我们的发现 小鼠对志贺氏菌有抵抗力的原因是因为小鼠具有强大的、特异性的先天免疫 肠上皮细胞的炎症小体反应。因此，缺乏炎症小体的小鼠很容易受到 口腔志贺氏菌感染并提供了第一个使用小鼠遗传和基因库的完整库的机会 在生理感染模型中剖析志贺氏菌发病机制的免疫学工具和方法。 重要的是，我们的数据表明，炎症体缺陷小鼠是一个高度相关的模型，因为 在人类中，我们发现志贺氏菌抑制或逃避 NAIP/NLRC4 炎症小体。我们提出三项具体 目标。在目标 1 中，我们将描述导致体内志贺氏菌病的先天免疫和细菌因素。 在目标 2 中，我们将描述小鼠对野生型和突变型志贺氏菌的适应性免疫反应。在， 目标 3，我们将检验志贺氏菌编码效应器使人类 NAIP/NLRC4 失活的假设 炎症小体。通过利用我们新模型的实验易处理性，我们希望找出关键 志贺氏菌感染期间介导免疫和疾病的因素，从而为 为开发更安全、更有效的疫苗提供信息。

Project Summary/Abstract Shigella species are highly infectious and important pathogens of humans. In 2016, there were an estimated 269 million cases and 212,000 deaths due to Shigella. Humans are typically infected with Shigella after oral ingestion of a minimal inoculum, consisting of as few as 10-100 bacteria. A major roadblock in Shigella research is the lack of an in vivo oral infection mouse model that recapitulates key aspects of human disease. Mice resist oral doses of Shigella as high as 100 million bacteria, but the reason for this resistance remains poorly understood. In our preliminary data, we describe our discovery that the reason mice are resistant to Shigella is because of a robust and mouse-specific innate immune inflammasome response in intestinal epithelial cells. Mice lacking inflammasomes are thus susceptible to oral Shigella infection and provide the first opportunity to use the full repertoire of mouse genetic and immunological tools and methodologies to dissect Shigella pathogenesis in a physiological infection model. Importantly, our data suggest that inflammasome-deficient mice are a highly relevant model because, in humans, we find Shigella inhibits or evades the NAIP/NLRC4 inflammasome. We propose three Specific Aims. In Aim 1, we will characterize innate immune and bacterial factors responsible for shigellosis in vivo. In Aim 2, we will characterize the adaptive immune responses of mice to wild-type and mutant Shigella. In, Aim 3, we will test the hypothesis that Shigella encodes effectors to inactivate the human NAIP/NLRC4 inflammasome. By exploiting the experimental tractability of our new model, we hope to identify the key factors mediating immunity and disease during Shigella infection, thereby providing a foundation of knowledge to inform the development of safer and more effective vaccines.