Immunity to Intracellular Pathogens

对细胞内病原体的免疫力

• 批准号: 6984813
• 负责人: EMIL Raphael UNANUE
• 金额: $ 37.35万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-12-01 至 2009-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6984813
• 关键词: Listeria; Listeria infections; SCID mouse; apoptosis; bacteria infection mechanism; bacterial cytopathogenic effect; bacterial proteins; bactericidal immunity; cell population study; histology; intracellular; laboratory mouse; leukocyte activation /transformation; lymphocyte; pore forming protein; proteolysis; recombinant proteins; transfection

DESCRIPTION (provided by applicant): This proposal examines infection with the facultative intracellular pathogen Listeria monocytogenes (LM), focusing on the early stage when LM is multiplying in tissues at a high exponential rate. During this period, precisely by the 48th hour, there is extensive lymphocyte death by apoptosis in lymphoid organs. The death is caused by the LM virulent pore forming protein Listeriolysin O (LLO). This proposal is based on three observations, the finding of extensive lymphocyte apoptosis in infective foci, our finding ex vivo and in vivo, that LLO is apoptogenic to lymphocytes; and observations indicating that the lymphocyte death stage may be linked to a period of lower resistance. The lower resistance became evident when SCID mice were found to handle the exponential growth phase better than normal mice. Pointedly, SCID mice injected with lymphocytes at the same time of infection, reverted to the pattern seen in normal mice, with higher LM burden. The plans include examining the molecular basis of LLO action on cells, to in vivo analysis of how LLO may be acting, plus an evaluation of the changes that take place in lymphoid organs at the time of the apoptotic phase. Accordingly, how LLO induces apoptotic death of lymphocytes is examined in detail. Preliminary evidence indicates that LLO initiates an intracellular proteolytic pathway that results in the death program. Experiments are planned to determine the nature of this pathway. Having a better understanding and pinpointing critical molecules in the death pathway may allow the infection to be modulated by targeting such molecules in a number of ways. Another important issue to examine is whether lymphocytes vary in their susceptibility to LLO apoptosis depending on their set and/or activation states: this issue is tackled by both in vivo and ex vivo experiments with purified cells. A LM that expresses LLO as a membrane protein is being engineered, in order to explore whether it is extracellular LLO that causes the lymphocyte death. The proposal includes a number of different approaches in order to determine whether lymphocyte apoptosis modulates in a negative way the infectious process. In summary, listeriosis is a powerful system to examine the relevance of lymphocyte death to the outcome of an infectious disease.

描述（由申请人提供）：本提案检查兼性细胞内病原体单核细胞增生李斯特氏菌 (LM) 的感染，重点关注 LM 在组织中以高指数速率繁殖的早期阶段。在此期间，正好到第 48 小时，淋巴器官中出现大量淋巴细胞因凋亡而死亡。 死亡是由 LM 有毒孔形成蛋白李斯特菌溶血素 O (LLO) 引起的。 该提议基于三个观察结果：感染病灶中广泛的淋巴细胞凋亡的发现，我们在离体和体内的发现，LLO 对淋巴细胞具有凋亡作用；观察结果表明淋巴细胞死亡阶段可能与抵抗力较低的时期有关。当发现 SCID 小鼠比正常小鼠更好地处理指数生长期时，较低的抵抗力变得明显。值得注意的是，在感染的同时注射淋巴细胞的 SCID 小鼠恢复到正常小鼠的模式，具有更高的 LM 负担。 这些计划包括检查 LLO 对细胞作用的分子基础，体内分析 LLO 如何发挥作用，以及评估细胞凋亡阶段时淋巴器官中发生的变化。因此，详细研究了LLO如何诱导淋巴细胞凋亡。 初步证据表明 LLO 启动细胞内蛋白水解途径，导致死亡程序。计划进行实验以确定该途径的性质。更好地理解和查明死亡途径中的关键分子可能会通过多种方式靶向这些分子来调节感染。另一个需要检查的重要问题是淋巴细胞对 LLO 凋亡的敏感性是否会根据其设置和/或激活状态而变化：这个问题可以通过纯化细胞的体内和离体实验来解决。正在设计一种以膜蛋白形式表达 LLO 的 LM，以探索是否是细胞外 LLO 导致淋巴细胞死亡。该提案包括许多不同的方法，以确定淋巴细胞凋亡是否以负面方式调节感染过程。总之，李斯特菌病是检查淋巴细胞死亡与传染病结果的相关性的强大系统。