Bacterial responses to reactive chlorine stress and their role in host-microbe interactions

项目总结/摘要 细菌和免疫系统之间的界面对人类健康至关重要， 我工作的长期目标是了解这种界面是如何调节的。两者在肠道的定植 病原菌和寄生菌对人类健康有重要影响。肠道微生物群落 受肠道氧化还原环境和先天免疫产生的氧化剂的强烈影响 系统在炎症过程中这些包括活性氧物质（ROS）和活性氯物质 （RCS）。RCS，包括次氯酸（HOCl）和活性氯胺，是强大的抗菌剂 氧化剂能够破坏许多细胞成分，包括蛋白质、脂质、辅因子和DNA。HOCl 是医疗、工业和家庭环境中非常常见的消毒剂，但RCS也是 嗜中性粒细胞的抗微生物武库，在炎症过程中积累，似乎对控制炎症很重要。 粘膜上皮细胞（例如肠道中的粘膜上皮细胞）的细菌定殖。人们对细菌是如何 它们构成了人体微生物组的感觉或对RCS做出反应，这种反应预计是至关重要的。 细菌在与人类免疫系统的相互作用中存活的能力。这项研究提出， 应用程序将使用转录组学，遗传学，生物化学和系统生物学技术来识别和 表征细菌用于感知和响应RCS的基因、蛋白质和途径，并将使用 哺乳动物细胞培养和动物研究，以测试这些机制在宿主-微生物相互作用中的作用。 我们的短期至中期目标集中在肠道微生物大肠杆菌和罗伊氏乳杆菌。E.杆菌 生理上非常好地表征，易于操作，并且促炎，而L.罗伊是反- 炎症和健康的微生物组相关。我们将识别和表征RCS传感 调节剂在这些生物体和表征的分子机制，这些调节剂和 它们控制的基因保护细菌免受RCS介导的损伤，并影响细菌之间的相互作用。 细菌和它们的哺乳动物宿主从长远来看，这些研究将扩展到其他模型 细菌，以表征整个微生物组多样性的RCS响应。的最终目标 这项研究是为了了解在医学上重要的细菌的RCS应激反应，特别是关注 它们在定殖和发病机制中的作用。这项研究计划的结果将推动 领域的氧化应激反应，阐明的基础上，在体内特异性的RCS传感转录 因素，有助于了解RCS毒性的根本原因，并可能导致识别新的 细菌和先天免疫系统之间的相互作用机制。这可能会导致新的 针对越来越多的炎症性疾病的微生物靶向治疗， 微生物组，并可能对我们理解宿主-微生物相互作用产生广泛影响， 发病机制、定殖和多种生物体中的RCS耐受性。

Project Summary/Abstract The interface between bacteria and the immune system is absolutely fundamental to human health, and the long-term goal of my work is to understand how that interface is regulated. Colonization of the gut by both pathogenic and commensal bacteria has major effects on human health. Gut microbial communities are strongly affected by the redox environment of the intestine and by oxidants produced by the innate immune system during inflammation. These include both reactive oxygen species (ROS) and reactive chlorine species (RCS). RCS, including hypochlorous acid (HOCl) and reactive chloramines, are powerful antimicrobial oxidants capable of damaging many cellular components, including proteins, lipids, cofactors, and DNA. HOCl is a very common disinfectant in medical, industrial, and home settings, but RCS are also a natural part of the antimicrobial arsenal of neutrophils, accumulate during inflammation, and appear to be important for controlling bacterial colonization of mucosal epithelia, such as those in the gut. Little is known about how the bacteria which make up the human microbiome sense or respond to RCS, and this response is expected to be critical for the ability of bacteria to survive interactions with the human immune system. The research proposed in this application will use transcriptomic, genetic, biochemical, and systems biology techniques to identify and characterize the genes, proteins, and pathways which bacteria use to sense and respond to RCS, and will use mammalian cell culture and animal studies to test the roles of these mechanisms in host-microbe interactions. Our short- to medium-term goals focus on the gut microbes Escherichia coli and Lactobacillus reuteri. E. coli is physiologically very well characterized, easy to manipulate, and pro-inflammatory, while L. reuteri is anti- inflammatory and associated with a healthy microbiome. We will identify and characterize RCS-sensing regulators in these organisms and characterize the molecular mechanisms by which those regulators and the genes they control protect the bacteria against RCS-mediated damage and influence interactions between bacteria and their mammalian hosts. In the longer-term, these studies will be expanded to other model bacteria in order to characterize RCS responses across the diversity of the microbiome. The ultimate goal of this research is to understand RCS stress responses in medically important bacteria, particularly focusing on the roles they play in colonization and pathogenesis. The results of this research program will advance the field of oxidative stress response, elucidate the basis for the in vivo specificity of RCS-sensing transcription factors, help understand the underlying causes of RCS toxicity, and may lead to identification of novel mechanisms of interaction between bacteria and the innate immune system. This could potentially lead to new microbe-targeted treatments for the growing list of inflammatory diseases known to be influenced by the microbiome, and may have broad implications for our understanding of host-microbe interactions, pathogenesis, colonization, and RCS tolerance in a wide variety of organisms.