Bile, Biofilms and Salmonella Gallbladder Carriage

描述(由申请人提供)：感染伤寒沙门氏菌可导致慢性的、相对无症状的人类胆囊炎。伤寒杆菌携带者是伤寒在人与人之间传播的主要原因。胆汁是胆汁的储存部位，胆汁是一种具有洗涤剂性质的抗菌物质。我们已经证明胆汁会影响一些沙门氏菌蛋白的表达，包括与毒力相关的几种表型(例如，上皮细胞侵袭、运动、抗菌/胆汁耐药性)。因此，对胆汁的感知和反应能力可能是沙门氏菌建立慢性携带者状态所必需的重要属性。此外，人类胆囊异常(特别是胆结石)与沙门氏菌携带者状态的发展存在高度相关性。我们先前已经证明，沙门氏菌在体外人体胆结石表面形成生物膜，并表征了参与这一过程的许多微生物因素。在目标1中，最近发现的胆汁调节基因，包括那些与宿主细胞入侵和抗菌素/胆汁耐药性有关的基因，将被用来揭示独特的胆汁反应感觉/调节通路。在目标2中，我们将通过对在沙门氏菌和胆结石的独特关系中起作用的微生物因子(细胞外基质)和胆结石因子的研究，进一步表征胆道运输的建立。我们还将探讨这样一种假设，即除了胆结石生物膜外，胆囊壁上皮细胞的侵袭和生物膜的形成在载体的发育中也起到了作用。最后，我们将通过检查来自人类携带者的胆结石、胆汁组织和胆汁来检验我们的假设和体外研究。AIMS 1和AIMS 2的结果将提供有关细菌与胆汁和胆结石环境相互作用的信息，以确定这种慢性感染的建立。所获得的知识可能会建议采用治疗性或预防性的方法来干扰胆汁抵抗、胆汁感觉或生物膜的形成，这可能会消除胆结石的携带，并极大地限制这种微生物的传播。 公众描述：伤寒可导致沙门氏菌的无症状携带和脱落。携带者的主要位置是胆囊部，但关于沙门氏菌如何引起这一器官的慢性感染，人们知之甚少。我们假设胆盐发出信号指示细菌的表型变化，使其适应胆囊中的生活，包括增强定植/生物膜能力和降低侵袭性。我们打算研究沙门氏菌中的胆汁信号，以及胆汁对胆结石生物膜和胆汁上皮细胞体外侵袭性的影响。计划中的实验还包括那些在人类携带者身上研究我们的假设的实验。

DESCRIPTION (provided by applicant): Infection with Salmonella typhi can cause a chronic, relatively asymptomatic infection of the human gallbladder. S. typhi carriers are responsible for much of the human-to-human spread of typhoid fever. The gallbladder is the storage site for bile, an antimicrobial substance with detergent-like properties. We have shown that bile affects the expression of a number of Salmonella proteins including those involved in several phenotypes associated with virulence (e.g. epithelial cell invasion, motility, antimicrobial/bile resistance). Therefore, the ability to sense and respond to bile is likely an important attribute of Salmonella necessary to establish a chronic carrier state. In addition, a high correlation exists between human gallbladder abnormalities (especially gallstones) and the development of the Salmonella carrier state. We have previously demonstrated that salmonellae form a biofilm on the surface of human gallstones in vitro, and have characterized numerous microbial factors involved in this process. In Aim 1, recently identified bile-regulated genes, including those involved in host cell invasion and antimicrobial/bile resistance will be used to uncover unique bile-responsive sensory/regulatory pathways. In Aim 2, we will further characterize the establishment of gallbladder carriage with the study of microbial factors (extracellular matrix) and gallstone factors that play a role in the unique relationship of salmonellae and gallstones. We will also explore the hypothesis that, in addition to gallstone biofilms, invasion of and biofilm formation on the gallbladder epithelium plays a role in carrier development. Finally, we will test our hypotheses and in vitro studies by examining gallstones, gallbladder tissue and bile from human carriers. The results from Aims 1 and 2 will provide information concerning the interplay of the bacterium with the gallbladder environment (bile and gallstones) on the establishment of this chronic infection. The knowledge gained may suggest therapeutic or preventative approaches to interfere with bile resistance, bile sensing, or biofilm formation, which could eliminate gallstone carriage and dramatically limit the spread of this organism. Public description: Typhoid fever can result in the asymptomatic carriage and shedding of Salmonella. The primary location of carriage is the gallbladder, but little is known about how Salmonella can cause chronic infection of this organ. We hypothesize that bile salts signal phenotypic changes in the bacterium that adapt it to life in the gallbladder, including enhanced colonization/biofilm capabilities and reduced invasiveness. We intend to study bile signaling in Salmonella, as well as the effect of bile on gallstone biofilms and gallbladder epithelial cell invasiveness in vitro. Planned experiments also include those to study our hypotheses in human carriers.