Role of B cells in controlling Klebsiella pneumoniae associated disease states

摘要 肺炎克雷伯氏菌(Kpn)是影响数百人的医疗保健相关感染的主要病原体。 全世界数以百万计的。血液性KPN感染尤其令人担忧，因为它们会导致高度患者 死亡率高，是一个主要的公共卫生负担。KPN在健康人的胃肠道(GI)定植 免疫功能受损的个体。在健康的个体中，细菌可以突破肠道上皮表面，并 进入循环系统，但很快就会被清除。在缺乏完全有效的免疫系统的患者中，KPN 会导致危及生命的全身性感染。迫切需要了解控制经济增长的因素 KPN从胃肠道传播到无菌部位。我们开发了一种自然获得性KPN GI的小鼠模型 定植以确定病原体和宿主因素，这些因素控制着病原体的获取、携带和传播。vbl.使用 在这个小鼠模型中，我们发现B细胞在控制胃肠道细菌负荷、全身传播、 和死亡率。在这个方案中，我们将研究B细胞调节KPN生长的机制。 胃肠道移位和全身扩散。在目标1中，我们将审查：a)预先存在的和KPN-- 诱导的(适应性的)粘膜和系统抗体调节KPN GI的生长和扩散，以及b) B细胞缺陷小鼠胃肠道不受抑制的生长和扩散的影响。这项工作将是 由目标2中的创新技术方法补充，该方法将揭示瓶颈和人口 两种野生型KPN在从口腔到肠道再到全身无菌部位的动态变化 和B细胞缺陷小鼠。在这里，我们将利用独一无二的条形码KPN种群，并结合高 识别易位事件、扩展动力学和起源的频率的分辨率测序 在不同的组织部位和血液中创建种群。最终，这项工作有望揭示 B细胞在控制KPN在宿主内不同部位的生长和扩散中的重要性 发生这种情况的机制。

SUMMARY Klebsiella pneumoniae (Kpn) is a primary causative agent of healthcare-associated infections affecting hundreds of millions worldwide. Bloodstream Kpn infections are of particular concern as they contribute to high patient mortality and represent a major public health burden. Kpn colonizes the gastrointestinal (GI) tract of healthy and immunocompromised individuals. In healthy individuals, bacteria can breach the intestinal epithelial surface and enter the circulatory system, but are rapidly cleared. In patients lacking a fully competent immune system, Kpn can cause life-threatening systemic infections. There is an urgent need to understand the factors that control the spread of Kpn from the GI tract to sterile sites. We developed a mouse model of naturally acquired Kpn GI colonization to identify pathogen and host factors which regulate acquisition, carriage, and dissemination. Using this mouse model, we found a critical role for B cells in controlling GI bacterial burden, systemic dissemination, and mortality. In this proposal, we will investigate the mechanisms by which B cells regulate Kpn growth in the GI tract, translocation, and systemic spread. In Aim 1, we will examine: a) the roles of pre-existing and Kpn- induced (adaptive) mucosal and systemic antibody in regulating Kpn GI growth and dissemination and b) the impact of dysbiosis in driving unchecked GI growth and dissemination in B cell-deficient mice. This work will be complemented by an innovative technical approach in Aim 2 which will reveal bottlenecks and population dynamics experienced by Kpn along the path from the mouth to the gut to systemic sterile sites in both wild type and B cell-deficient mice. Here we will leverage a uniquely barcoded Kpn population in combination with high- resolution sequencing to identify frequencies of translocation events, expansion dynamics, and the origination of founding populations within distinct tissue sites and blood. Ultimately, this work is expected to reveal the importance of B cells in controlling Kpn growth and dissemination at various sites within the host and the mechanisms by which this occurs.