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

描述（由申请人提供）：本研究的长期目标是阐明血管系统内皮细胞的免疫机制，这些免疫机制损害或引发针对内皮靶向感染因子（如立克次氏体）的有效免疫应答。这些专性胞内细菌包括潜在用于生物恐怖主义的试剂，如立克次氏体（落基山斑疹热的原因）和立克次氏体。流行性斑疹伤寒的病因。在适当的小鼠模型中，有效的抗立克次体免疫应答涉及NK细胞、CD 8 + T细胞和内皮细胞的杀立克次体机制的激活;然而，C57 BL/6小鼠对立克次体感染的抵抗力显著高于C3 H/HeN小鼠，尽管CD 8 + T细胞是完全清除两种菌株中立克次体所必需的。鉴于内皮细胞通过表达多种免疫应答基因来应答立克次体感染，我们假设立克次体感染的内皮细胞的炎症表型影响针对立克次体的先天性和/或适应性免疫的发展。因此，本申请的目的是了解内皮在产生有效或无效的抗立克次体免疫应答中的作用。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性表型在内皮细胞、NK细胞和CD 8 + 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初始CD 8 + T淋巴细胞活化或耐受中的体内作用。我将通过1）比较立克次体感染的原代内皮细胞培养物和来自敏感和抗性小鼠的组织的杀立克次体活性和MHC-I类、T细胞共刺激分子和NK细胞配体的表达来实现这些目标; 2）测量任一小鼠品系的立克次体感染的内皮细胞刺激的NK细胞和CD 8 + T细胞的效应功能的差异;和3）比较任一品系的小鼠嵌合体中初始CD 8 + T细胞的致敏或耐受化，其中MHC I类分子由内皮细胞而不是骨髓来源的细胞表达。这项研究对健康的影响是，它将扩大知识，合理设计有效的疫苗对立克次体疾病;这一信息将适用于其他内皮靶向传染性病原体以及疾病，其中内皮细胞可能发挥重要作用，如动脉粥样硬化，癌症和血管炎。

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.