Genetic Approaches to Evaluation of the Roles of Leptospira interrogans Adhesins in Endothelial Interactions

摘要 钩端螺旋体病是由钩端螺旋体属的几种致病螺旋体引起的 是世界上传播最广的人畜共患病。钩端螺旋体属的病原体是 维持在人畜共患病的循环中，要求他们能够建立持久的， 在具有免疫能力的宿主动物中的播散性感染，但该属还包括 腐生的、非致病的物种。水库宿主不会发展成严重的疾病，但 钩端螺旋体-宿主相互作用的结果取决于宿主物种，钩端螺旋体物种， 血清学变异(血清型)和其他未知因素。人类的疾病范围从 轻度自限性疾病到危及生命的急性感染合并肾功能衰竭和肝脏 功能障碍、广泛的内皮损伤、通透性增加和出血。 内皮屏障的破坏可能会促进传播，并有助于 出血性疾病的表现。我们重点研究了两国之间的互动 内皮细胞表面受体和钩端螺旋体的体外鉴定 问号钩端螺旋体的受体，以及识别的候选问号钩端螺旋体粘附素(表示 LIC11574和LIC13411)与VE-钙粘附素结合，VE-钙粘附素是主要的内皮屏障决定因素。 我们假设多个粘附素与宿主跨膜受体的黏附 有助于破坏内皮屏障和细菌的移行。 在本提案中，我们将采取多种方法来确定以前的角色 确定粘附素在细菌移行、VE-钙粘附素的破坏和 跨内皮细胞电阻(TEER)。我们将使用TN突变体，并获得功能 一株腐生菌株产生VE-钙粘附素的衍生物，以评估其潜力 7种粘附素的作用。创新之处在于使用了两套转基因钩端螺旋体菌株 我们的内皮细胞培养模型。在目标1中，我们将描述问号钩端螺旋体的表型 编码已知或候选粘附素的基因中的转座子突变 跨内皮层的轮回。在目标2中，我们将类似地刻画函数的增益 腐生菌株产生结合VE-钙粘附素的问号钩端螺旋体粘附素。 我们提议的工作将是朝着解决生物学基本问题迈出的重要一步。 钩端螺旋体的哪些功能决定因素将病原体与 非病原体。拟议的工作还将采取步骤，解决长期存在的 该领域的争议：内皮损伤是细菌与血管内皮细胞相互作用的结果 血管内皮细胞还是对宿主的反应，影响越来越大。

Abstract Leptospirosis is caused by several pathogenic species of spirochetes of the genus Leptospira and is the most widespread zoonosis worldwide. Pathogens in the genus Leptospira are maintained in zoonotic cycles, demanding that they be able to establish persistent, disseminated infection in immunocompetent host animals, but the genus also includes saprophytic, non-pathogenic species. Reservoir hosts do not develop severe disease, but the outcome of the Leptospira-host interaction depends on the host species, the Leptospira species, serological variant (serovar), and additional unknown factors. Disease in humans ranges from mild self-limited illness to acute life-threatening infection with kidney failure, and liver dysfunction, and widespread endothelial damage, increased permeability, and hemorrhage. Disruption of endothelial barriers is likely to facilitate dissemination and to contribute to hemorrhagic disease manifestations. We have focused on investigation of interactions between endothelial cell surface receptors and Leptospira in vitro, identified endothelial cell-surface receptors for L. interrogans, and identified candidate L. interrogans adhesins (denoted LIC11574 and LIC13411) that bind to VE-cadherin, the primary endothelial barrier determinant. We hypothesize that adhesion to host transmembrane receptors by multiple adhesins contributes to disruption of endothelial barriers and transmigration of the bacteria. In this proposal, we will take multiple approaches to determining the roles of previously identified adhesins in bacterial transmigration, disruption of VE-cadherin, and changes in transendothelial electrical resistance (TEER). We will employ Tn mutants, and gain of function derivatives of a saprophytic strain that produce VE-cadherin adhesins, to evaluate the potential roles of 7 adhesins. Innovation lies in use of both genetically modified Leptospira strain sets in our endothelial cell culture model. In Aim 1 we will characterize the phenotypes of L. interrogans transposon mutants in genes encoding known or candidate adhesins for adhesion to and transmigration across endothelial layers. In Aim 2 we will similarly characterize gain of function saprophytic strains producing L. interrogans adhesins that bind VE-cadherin. Our proposed work will constitute a major step toward resolving the biologically fundamental question of what are the functional determinants of Leptospira that separate the pathogens from the non-pathogens. The proposed work will also take steps toward resolving a long-standing controversy in the field: Is endothelial damage the result of bacterial interactions with the endothelium or to the host response, increasing impact.