Mucosal colonization and dissemination of P. aeruginosa

描述(由申请人提供)：这个项目的中心目标是更好地了解免疫低下患者中由内毒素平滑菌株铜绿假单胞菌引起的感染的发病机制和免疫力。基于发起人实验室和合作者之前的研究，我们建立了一个可复制的铜绿假单胞菌胃肠道定植和中性粒细胞减少期间全身传播的小鼠模型。使用这一模型的初步研究已经确定了胃肠道定植和传播所必需的几个因素。值得注意的是，不需要在定殖中起重要作用的毒力因子，即药丸和鞭毛，而需要的是内毒素-外核多糖和O-侧链。中性粒细胞减少的持续时间和强度与环磷酰胺的剂量有关，在确定传播所需的毒力因素时很重要。这些初步实验得出了以下可检验的假说：铜绿假单胞菌在胃肠道粘膜定植、移位和引起菌血症所需的表面因子尚不完全清楚。这些因子的鉴定可以在小鼠模型中完成，该模型将定义病原体毒力因子(定植和移位因子)和宿主免疫反应(细胞和体液免疫效应因子)。这一发现可能导致有效干扰黏膜定植和传播的方法，并减少免疫受损宿主中铜绿假单胞菌感染的影响。在目标1中，将利用微阵列和TRASH(转座子位点杂交)技术鉴定铜绿假单胞菌建立胃肠道定植、移位和传播所需的毒力因子，并创建突变株用于在定植/传播模型中进行测试。在目标2中，将进一步描述防止铜绿假单胞菌定植和传播所必需的宿主免疫效应器(细胞和体液天然免疫)的作用。应聘者寻求强化、正式和有指导的培训，以提供必要的智力和技术工具，以实现作为一名科学家的独立。作为一名儿科血液学/肿瘤学和传染病专家，他的长期目标是开发预防或改善铜绿假单胞菌感染后果的策略和潜在的治疗方法。

DESCRIPTION (provided by applicant): The central goal of this project is to gain a better understanding of the pathogenesis of and immunity to infections caused by LPS-smooth strains P. aeruginosa strains in immunocompromised patients. Based on previous studies by the sponsor's laboratory and collaborators, we have established a reproducible mouse model of P. aeruginosa gastrointestinal-colonization and systemic spread during neutropenia. Preliminary studies using this model have identified several factors that are necessary for gastrointestinal colonization and dissemination. Of note, virulence factors expected to play an important role in colonization, namely pill and flagella, were not needed whereas LPS-outer core polysaccharide and O-side chains were. The duration and intensity of neutropenia, related to cyclophosphamide dose, was important in identifying virulence factors needed for dissemination. These preliminary experiments have led to the following testable hypothesis: Surface factors of P. aeruginosa needed to colonize the gastrointestinal mucosa and to translocate and cause bacteremia are not fully known. Identification of such factors can be accomplished in a murine model that will define both pathogen virulence factors (colonization and translocation factors) and host immune responses (cellular and humoral immune effectors). The findings could lead to means to effectively disrupt mucosal colonization and dissemination and diminish the impact of P. aeruginosa infection in immunocompromised hosts. In Aim 1, virulence factors needed by P. aeruginosa to establish gastrointestinal colonization, translocation, and dissemination will be identified by use of microarray and TraSH (transposon site hybridization) technology, and mutants will be created for testing in the colonization/dissemination model. In Aim 2, the role of host immune effectors (cellular and humoral innate immunity) that are necessary for preventing P. aeruginosa colonization and dissemination will be further delineated. The candidate seeks an intensive, formal, and mentored training to provide the necessary intellectual and technical tools to achieve independence as a scientist. As a specialist in pediatric hematology/oncology and infectious diseases, his long-term goal is to develop strategies and potential therapies to prevent or ameliorate the consequences of P. aeruginosa infections.