The endothelium and resistance to rickettsial infection

描述（由申请人提供）：斑点热立克次体病在世界各地重新出现。这些都是蜱虫传播的细菌感染，被严重低估。立克次氏体的主要靶标血管内皮的感染触发促炎表型的内皮活化和导致血管内流体渗漏到所有器官中和凝血活化的不同程度的损伤。内皮对立克次体感染的反应的所有数据都是在体外用静态条件下培养的大血管内皮细胞系和原代内皮细胞产生的。问题是体外培养的内皮细胞与体内的内皮细胞非常不同，因为它们的表型受组织微环境和管腔侧恒定血流的生理调节。另一方面，在小鼠内皮正确模拟人类内皮的假设下进行了小鼠研究;然而，这一说法尚未得到证实。缺乏在立克次体感染的体内实验系统，重点对人类的微血管内皮细胞是一个主要的需要，必须解决，以填补差距，在立克次体的发病机制中的内皮细胞在体内的作用，我们的理解。因此，我们的目标是产生一个相关的人体内皮细胞的体内实验模型，并表征立克次体感染的表型。我们的中心假设是，小鼠内皮细胞在体内立克次体感染的转录反应是不同的人内皮细胞在体内和非常不同的静态条件下的内皮细胞在体外的反应。检验我们假设的两个具体目标是：1）产生感染立克次体的人内皮的实验性体内模型;和2）鉴定感染立克次体的体外和体内内皮细胞之间的差异。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）对内皮细胞和小鼠内皮细胞体外研究的有效性进行关键评估，作为人内皮细胞对立克次体感染的反应模型。这些贡献是重要的，因为它们将提供有效的模型来研究内皮在立克次体发病机制中的作用，并详细了解人类内皮对立克次体感染的反应。我们研究的创新在于通过实施新的人体内皮细胞体内生理实验系统来弥合动物和人体实验之间的差距，并且我们能够专注于立克次体靶细胞的转录组，而不会产生更常用的整个组织转录谱所产生的信号稀释。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，其中单独使用抗生素是不够的。 公共卫生相关性：为了支持美国国立卫生研究院改善健康的使命，我们将进一步了解人类内皮细胞对立克次体感染的反应。这将为发现新的干预靶点开辟新的领域，当单独使用抗生素无法预防重大并发症和死亡时，这些靶点可用于控制晚期感染。这里产生的知识不仅有助于内皮生物学和立克次体免疫学领域，而且还将影响血管内皮细胞在发病机制中发挥重要作用的其他领域，如动脉粥样硬化，癌症，自身免疫性血管炎和实体器官移植。

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.