Mechanistic study of flagellin-induced inflammation

描述（由申请人提供）：该补助金的目标有两个方面：第一是为主要研究人员建立资金，以确保教师职位并制定独立的研究计划。第二个目标是进一步表征细菌及其产物与肠上皮宿主细胞的相互作用。具体而言，提出了鉴定致病性细菌鞭毛蛋白的诱导促炎反应的特定区域的实验，并确定这些区域如何跨极化上皮细胞易位以允许识别位于基底外侧表面上的Toll样受体5（TLR 5）.革兰氏阴性菌休克是由微生物及其产物诱导的促炎基因介导的。在革兰氏阴性菌的表面成分中，沙门氏菌和其他致病菌释放的蛋白质（称为鞭毛蛋白）已显示出在许多哺乳动物细胞中有效诱导各种促炎反应。鞭毛蛋白是鞭毛的主要结构成分，来自沙门氏菌属物种和其他有鞭毛的细菌，具有高度保守的氨基和羧基末端以及高变的中心区域。宿主对鞭毛蛋白的反应正在阐明，但还需要进一步的工作。已经显示鞭毛蛋白的保守区域通过IkBa/NF-kB途径在肠上皮细胞中诱导强烈的炎症反应，例如IL-8分泌和一氧化氮产生。这种对鞭毛蛋白的炎症反应似乎是由位于肠上皮细胞基底外侧表面的TLR 5介导的。这些数据表明，鞭毛蛋白在宿主细菌感染期间上调炎症中起着至关重要的作用，并且是TLR 5识别的主要微生物因子。这项建议的具体目标是：1）在都柏林沙门氏菌的保守末端内建立最小促炎结构域，以及其它病原性细菌鞭毛蛋白，并确定这些相同区域是否介导TLR 5结合，和2）确定活沙门氏菌介导鞭毛蛋白跨肠上皮细胞易位诱导炎症反应的机制，非致病性肠道细菌植物群。这些研究将深入了解细菌和宿主细胞的相互作用，这对于建立疾病至关重要，并将为治疗的开发提供新的途径。

DESCRIPTION (provided by applicant): The goals of this grant are two-fold: The first is to establish funding for the principle investigator to secure a faculty position and develop an independent research program. The second goal is to further characterize the interaction of bacteria and their products with intestinal epithelial host cells. Specifically, experiments are proposed to identify specific regions of pathogenic bacterial flagellin that induce proinflammatory responses and establish how these regions are translocated across polarized epithelial cells to allow recognition of toll- like receptor 5 (TLR5) localized on the basolateral surface. Gram-negative bacterial shock is mediated by the actions of proinflammatory genes induced in response to microbes and their products. Among the surface components of Gram-negative bacteria, a protein that is released by Salmonella, and other pathogenic bacteria, known as flagellin has been shown to potently induce a variety of proinflammatory responses in a number of mammalian cells. Flagellin, the primary structural component of flagella, from Salmonella species and other flagellated bacteria has highly conserved amino and carboxyl termini and a hypervariable central region. The host response to flagellin is being elucidated but additional work is necessary. The conserved regions of flagellin have been shown to induce a vigorous inflammatory response such as lL-8 secretion and nitric oxide production in intestinal epithelial cells via the IkBa/NF-kB pathway. This inflammatory response to flagellin appears to be mediated by TLR5 located on the basolateral surface of intestinal epithelial cells. The data indicates that flagellin plays a crucial role in upregulating inflammation during bacterial infection of the host and is primary microbial factor recognized by the TLR5. The specific aims of this proposal are: 1) to establish the minimal proinflammatory domain(s) within the conserved termini of Salmonella dublin, as well as other pathogenic bacterial flagellin proteins and determine if these same region(s) mediate TLR5 binding, and 2) to determine the mechanism by which live Salmonella mediate the translocation of flagellin across intestinal epithelial cells inducing inflammatory responses in contrast to nonpathogenic intestinal bacterial flora. These studies will provide insights into bacterial and host cells interactions that are critical for establishing disease and will offer new avenues for the development of treatment.