Role of the endothelium in the T cell-mediated anti-rickettsial immune response

描述(申请人提供)：这项研究的长期目标是阐明血管系统衬里的内皮细胞的免疫机制，这些免疫机制可以损害或引发有效的免疫反应，以对抗内皮靶标的感染性病原体，如立克次体。这些专性胞内细菌包括可能用于生物恐怖主义的制剂，如立克次体(落基山斑点热病的起因)和普罗瓦泽克立克次体(流行性斑疹伤寒的起因)。在合适的小鼠模型中，有效的抗立克次体免疫反应涉及NK细胞、CD8+T细胞和激活内皮细胞的立克次体杀灭机制；然而，尽管CD8+T细胞是两株立克次体完全清除所必需的，但C57BL/6小鼠对立克次体感染的抵抗力明显高于C3H/HEN小鼠。鉴于内皮细胞通过表达多个免疫应答基因来应答立克次体感染，我们假设感染立克次体的内皮细胞的炎症表型影响对立克次体的天然和/或获得性免疫的发展。因此，这项应用的目的是了解内皮细胞在产生有效或无效的抗立克次体免疫反应中的作用。我将通过以下具体目标来实现这一目标：1)确定立克次体诱导的内皮炎症表型在内皮细胞、NK细胞和CD8+T细胞的效应功能中的作用；2)确定立克次体感染的内皮细胞在体内对初始CD8+T淋巴细胞的激活或耐受的作用。我将通过以下方式实现这些目标：1)比较感染立克次体的原代内皮细胞培养和敏感和耐药小鼠组织中MHC-I类分子、T细胞共刺激分子和NK细胞配体的杀伤活性及表达；2)测量两种立克次体感染的小鼠内皮细胞激活的NK细胞和CD8+T细胞的效应功能的差异；以及3)比较两种品系小鼠嵌合体中幼稚CD8+T细胞的启动或耐受能力，在这两种嵌合体中，MHC I类分子由内皮细胞表达，但不由骨髓来源的细胞表达。这项研究对健康的影响是，它将拓宽合理设计有效的立克次体疾病疫苗所需的知识；这些信息将适用于其他内皮靶标感染剂以及内皮细胞可能在其中发挥重要作用的疾病，如动脉粥样硬化、癌症和脉管炎。

DESCRIPTION (provided by applicant): The long-term goal of this research is to elucidate the immune mechanisms of endothelial cells lining the vascular system that either impair or elicit effective immune responses against endothelium-target infectious agents such us rickettsiae. These obligately intracellular bacteria include agents of potential use for bioterrorism such as Rickettsia rickettsii (the cause of Rocky Mountain spotted fever) and R. prowazekii (the cause of epidemic typhus). In adequate mouse models, the effective anti-rickettsial immune response involves NK cells, CD8+ T cells, and the activation of rickettsicidal mechanisms of endothelial cells; however, C57BL/6 mice are significantly more resistant to rickettsial infection than C3H/HeN mice despite the fact that CD8+ T cells are necessary for the complete clearance of rickettsiae in both strains. Given that endothelial cells respond to rickettsial infection by expressing multiple immune response genes, we hypothesize that the inflammatory phenotype of rickettsia-infected endothelial cells influences the development of the innate and/or adaptive immunity against rickettsiae. Thus, the objective of this application is to understand the role of the endothelium in the production of effective or ineffective anti- rickettsial immune responses. I will approach this objective through the following specific aims: 1) Determine the role of the rickettsia-induced endothelial inflammatory phenotype in the effector functions of endothelial cells, NK cells and CD8+ T cells; and 2) Determine the in vivo role of rickettsia-infected endothelial cells in the activation or tolerization of naive CD8+ T lymphocytes. I will carry out these aims by 1) comparing the rickettsicidal activity and expression of MHC-class I, T cell costimulatory molecules, and NK cell ligands of rickettsia-infected primary endothelial cell cultures and tissues from susceptible and resistant mice; 2) measuring the differences in effector functions of NK cells and CD8+ T cells stimulated by rickettsia-infected endothelial cells of either mouse strain; and 3) comparing the priming or tolerization of naive CD8+ T cells in mouse chimeras of either strain in which MHC class I molecules are expressed by endothelial cells but not by cells of bone marrow origin. The health impact of this research is that it will broaden the knowledge necessary for the rational design of effective vaccines against rickettsial diseases; this information will be applicable to other endothelial-target infectious agents as well as diseases in which endothelial cells might play an important role such as atherosclerosis, cancer, and vasculitides.