Bile, Biofilms and Salmonella Gallbladder Carriage

描述（由申请人提供）：伤寒沙门氏菌感染可引起慢性，相对无症状的人类胆囊感染。伤寒沙门氏菌携带者是造成伤寒在人与人之间传播的主要原因。胆囊是胆汁的储存场所，胆汁是一种具有清洁剂性质的抗菌物质。我们已经证明，胆汁影响许多沙门氏菌蛋白的表达，包括那些与毒力相关的几种表型（如上皮细胞侵袭、运动性、抗微生物/胆汁耐药性）。因此，感知胆汁和对胆汁作出反应的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（尤其是胆结石）与沙门氏菌携带者状态的发展存在高度相关性。我们之前已经证明，沙门氏菌在体外人类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Aim 1中，最近发现的胆汁调节基因，包括那些参与宿主细胞入侵和抗微生物/胆汁抗性的基因，将用于揭示独特的胆汁反应感觉/调节途径。在Aim 2中，我们将通过研究微生物因素（细胞外基质）和胆结石因素进一步表征胆囊运输的建立，这些因素在沙门氏菌和胆结石的独特关系中发挥作用。我们还将探讨除了胆结石生物膜外，胆囊上皮的浸润和生物膜形成在载体发育中起作用的假设。最后，我们将通过检查人类携带者的胆结石、胆囊组织和胆汁来检验我们的假设和体外研究。目的1和目的2的结果将提供有关细菌与胆囊环境（胆汁和胆结石）在建立这种慢性感染中的相互作用的信息。所获得的知识可能提示干预胆汁抵抗、胆汁感知或生物膜形成的治疗或预防方法，这可以消除胆结石携带并显著限制该生物体的传播。

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.