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

项目概要/摘要 志贺氏菌属是人类的重要病原体，具有高度传染性。2016年，有一个 估计有2.69亿病例和21.2万人死于志贺氏菌。人类通常会感染 志贺氏菌在口服摄入最小接种物后，由少至10-100个细菌组成。一个主要 志贺氏菌研究的障碍是缺乏体内口腔感染小鼠模型， 人类疾病的各个方面。小鼠抵抗口服剂量的志贺氏菌高达1亿个细菌，但原因是 因为这种抵抗力仍然知之甚少。在我们的初步数据中，我们描述了我们的发现， 小鼠对志贺氏菌具有抵抗力的原因是小鼠特异性的强大先天免疫 肠上皮细胞的炎性小体反应。因此，缺乏炎性小体的小鼠容易受到 口服志贺氏菌感染，并提供了第一次机会，使用小鼠遗传和 免疫学工具和方法来剖析志贺氏菌在生理感染模型中的发病机制。 重要的是，我们的数据表明，炎性小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/NLRC 4炎性体。我们提出三个具体的 目标。在目标1中，我们将描述先天免疫和细菌因素在体内志贺菌病。 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应答。在， 目的3，我们将检验志贺氏菌编码效应子以抑制人NAIP/NLRC 4的假设 炎性小体通过利用我们新模型的实验易处理性，我们希望找到关键 志贺氏菌感染过程中免疫和疾病的调节因子，从而为志贺氏菌感染的免疫调节提供了基础。 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.