The endothelium and resistance to rickettsial infection

描述（由申请人提供）：斑点热立克次体在世界各地重新出现。这些是蜱传播的细菌感染，被严重低估了。立克次体的主要靶点血管内皮的感染，触发内皮活化的促炎表型和不同程度的损伤，导致血管内液体渗漏到所有器官和激活凝血。内皮对立克次体感染反应的所有数据都是在体外用静态条件下培养的内皮细胞系和源自大血管的原代内皮细胞生成的。问题是，体外培养的内皮细胞与体内培养的内皮细胞非常不同，因为它们的表型在生理上受到组织微环境和管腔侧持续血流的调节。另一方面，在小鼠身上的研究是在小鼠内皮正确模拟人类内皮的假设下进行的；然而，这一说法尚未得到证实。缺乏专注于人类微血管内皮细胞的立克次体感染的体内实验系统是必须解决的主要需求，以填补我们对内皮在立克次体发病机制中的体内作用的理解的空白。因此，我们的目标是建立一个相关的人内皮的体内实验模型，并描述立克次体感染反应的表型。我们的中心假设是，小鼠内皮在体内对立克次体感染的转录反应不同于人内皮在体内的转录反应，也不同于内皮在体外静态条件下的转录反应。验证我们假设的两个具体目标是：1)建立立克次体感染人内皮的实验体内模型；2)确定体外和体内内皮细胞感染立克次体的差异。我们的研究将有两方面的贡献：1)详细了解人内皮细胞对立克次体感染的体内表型；2)对内皮和小鼠内皮作为人类内皮响应立克次体感染模型的体外研究的有效性进行了关键评估。这些贡献是重要的，因为它们将为研究内皮在立克次体发病机制中的作用提供有效的模型，并为人类内皮对立克次体感染的反应提供详细的分子知识。我们研究的创新在于通过实施新的人体内皮体内生理实验系统，弥合动物和人体实验之间的差距，我们能够专注于立克次体靶细胞的转录组，而不需要更常用的整个组织转录谱产生的信号稀释。在推进内皮生物学和立克次体免疫学领域的同时，我们的研究结果将产生一个相关的模型，用于发现和测试控制晚期立克次体感染的治疗策略，而仅靠抗生素是不够的。

DESCRIPTION (provided by applicant): Spotted fever rickettsioses are re-emerging throughout the world. These are tick-transmitted bacterial infections that are severely underreported. Infection of Rickettsia's main target, the vascular endothelium, triggers endothelial activation of a proinflammatory phenotype and various degrees of damage that result in leakage of intravascular fluid into all organs and activation of coagulation. All data of the response of the endothelium to rickettsial infection has been generated exclusively in vitro with endothelial cell lines and primary endothelial cells derived from large vessels cultured under static conditions. The problem is that endothelial cells cultivated in vitro are very different from endothelial cells in vivo since their phenotype is physiologically regulated by the tissue microenvironment and by constant blood flow on the luminal side. On the other hand, work on mice has been performed under the assumption that the mouse endothelium correctly models the human endothelium; however, this claim has not been substantiated. The lack of in vivo experimental systems of rickettsial infection that focus on human endothelial cells of the microvasculature is a major need that must be addressed to fill the gap in our understanding of the in vivo role of the endothelium in rickettsial pathogenesis. Thus, our objective is to produce a relevant in vivo experimental model of the human endothelium and characterize the phenotype in response to rickettsial infection. Our central hypothesis is that the transcriptional response of the mouse endothelium in response to rickettsial infection in vivo is unlike that of the human endothelium in vivo and very different from the response of the endothelium in vitro under static conditions. The two specific aims to test our hypothesis are: 1) Produce an experimental in vivo model of the human endothelium infected with Rickettsia; and 2) Identify the differences between in vitro and in vivo endothelial cells infected with Rickettsia. The contribution of our research will be twofold: 1) a detailed understanding of the in vivo phenotype of human endothelial cells in response to infection with Rickettsia; and 2) a critical assessment of the validity of in vitro studies of the endothelium and of the mouse endothelium as a model of the human endothelium responding to rickettsial infections. These contributions are significant because they will provide validated models to study the role of the endothelium in rickettsial pathogenesis and a detailed molecular knowledge of the response of the human endothelium to rickettsial infection. The innovation of our research lays in bridging the gap between animal and human experimentation by implementing novel in vivo physiological experimental systems of the human endothelium and our ability to focus on the transcriptome of the target cells of Rickettsia without the signal dilution produced by the more commonly used transcriptional profiling of whole tissues. While advancing the fields of endothelial biology and rickettsial immunology, our results will generate a relevant model for discovering and testing therapeutic strategies to control advanced rickettsial infections where antibiotics alone will not be sufficient. PUBLIC HEALTH RELEVANCE: In support of the mission of the NIH to improve health, we will refine our understanding of the response of the human endothelium to rickettsial infection. This will open the field for the discovery of novel targets of intervention that may be used to control advanced infections when antibiotics alone will not prevent major complications and fatalities. The knowledge generated here will not only contribute to the fields of endothelial biology and rickettsial immunology, but will also impact other fields where vascular endothelial cells play an important role in pathogenesis such as atherosclerosis, cancer, autoimmune vasculitides, and solid organ transplantation.