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，这些细胞损害或引发针对内皮靶感染性病原体（如立克次体）的有效免疫反应。这些专性细胞内细菌包括可能用于生物恐怖主义的病原体，如立克次体立克次体（引起落基山斑疹热）和普拉兹克氏热原（引起流行性斑疹伤寒）。在适当的小鼠模型中，有效的抗立克次体免疫反应涉及NK细胞、CD8+ T细胞和内皮细胞的立克次体杀死机制的激活；然而，C57BL/6小鼠对立克次体感染的抵抗力明显高于C3H/HeN小鼠，尽管CD8+ T细胞是完全清除立克次体所必需的。鉴于内皮细胞通过表达多种免疫应答基因对立克次体感染做出反应，我们假设立克次体感染内皮细胞的炎症表型影响了对立克次体的先天和/或适应性免疫的发展。因此，本应用的目的是了解内皮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细胞效应功能中的作用；2)确定立克次体感染内皮细胞在激活或耐受初始CD8+ T淋巴细胞中的体内作用。我将通过1)比较立克次体感染的原代内皮细胞培养物和易感和耐药小鼠组织的mhc - I类、T细胞共刺激分子和NK细胞配体的活性和表达来实现这些目标；2)检测立克次体感染的内皮细胞刺激NK细胞和CD8+ T细胞效应功能的差异；3)比较在内皮细胞而非骨髓细胞表达MHC I类分子的两种菌株的小鼠嵌合体中初始CD8+ T细胞的启动或耐受性。这项研究对健康的影响是，它将扩大合理设计针对立克次体病的有效疫苗所必需的知识；这一信息将适用于其他内皮靶感染因子，以及内皮细胞可能起重要作用的疾病，如动脉粥样硬化、癌症和血管增生。

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.