Inter-kingdom Signalling: Modulation of Mast cells by Commensal Bacteria

背景和原理：肥大细胞长期以来被认为是人类过敏性疾病的关键效应细胞，现在被认为是先天免疫反应和获得性免疫反应的主要诱导者和放大器。它们在呼吸道和肠道粘膜中的大量存在表明它们在这些入口处作为重要的守门人/哨兵在对抗感染生物方面发挥了作用。然而，肥大细胞在抵御病原体的第一线的位置也表明，它们可能在促进宿主-微生物组关系和维持超级有机体的复杂生态系统中发挥重要作用。*基于我们之前的研究和其他人的研究，非致病细菌似乎可以利用不同的机制来稳定肥大细胞，通过细胞与细胞的直接相互作用，通过分泌介质，并可能通过释放膜微囊来发挥作用。我们还确定了肥大细胞上的受体和离子通道，它们是新型细菌信号系统的潜在靶点。*目标：该研究计划的长期目标是了解新的跨王国通信系统背后的分子机制，并有助于我们理解这些系统在塑造细菌与其哺乳动物宿主之间的关系中所起的作用。本申请中提出的实验将通过追求以下特定目标来研究微生物对肥大细胞功能的调节：*确定各种非致病微生物、微生物释放的微泡和代谢产物对肥大细胞表型和功能的影响。*确定微生物对肥大细胞功能影响的信号通路。*确定潜在的肥大细胞受体，涉及宿主/微生物相互作用的新方面。*实验方法：我们将重点研究乳杆菌和非致病性大肠杆菌菌株对原代小鼠肥大细胞的影响。我们将检查直接接触完整细菌、微泡和分泌物的影响。除了评估介质释放和迁移的变化外，我们还将研究肥大细胞向调节表型的潜在转换。将结合药理学方法、转基因肥大细胞和电生理学来确定肥大细胞对细菌信号的反应所涉及的受体、离子通道和通路。*结果：拟议研究的完成将使我们对哺乳动物和细菌之间的相互作用有更深入的了解，而不是传统的先天免疫观点。除了识别新的跨王国交流模式外，这项研究还将提供对共生关系如何塑造哺乳动物生理的洞察。因此，这是一项基础性研究，对生物科学具有潜在的广泛影响。**

Background and Rationale: Mast cells long regarded as key effectors of human allergic disease are now considered primary inducers and amplifiers of both innate and adaptive immune responses. Their presence in high numbers in the airway and gut mucosa is indicative of their role as important gatekeepers/sentinels for fighting infectious organisms at these portals of entry. However, the position of mast cells on the frontline of defense against pathogens also suggests they may play an important role in fostering the host-microbiome relationship and maintaining the complex ecosystem of the super-organism. ***Based on our previous studies, and those of others, it appears that non-pathogenic bacteria can utilize distinct mechanisms to stabilize mast cells acting by direct cell-cell interaction, through secretion of mediators and possibly through the release of membrane micro-vesicles. We have also identified receptors and ion channels on the mast cell that are potential targets for novel bacterial signalling systems. ******Objectives: The long-term objective of this research program is to understand the molecular mechanisms underlying novel inter-kingdom communication systems and to contribute to our understanding of the role these systems play in shaping the relationship between bacteria and their mammalian hosts. The experiments proposed in this application will examine microbe-mediated regulation of mast cell function by pursuing the following specific aims:*** Determine the influence of diverse non-pathogenic microbes, microbe shed microvesicles and metabolites on mast cell phenotype and function. *** Determine the signaling pathways underlying the functional effects of microbes on mast cells. *** Identify potential mast cell receptors involved in novel aspects of host/microbe interactions.******Experimental approach: We will focus on the effect of strains of Lactobacilli and non-pathogenic E.coli on primary murine mast cells. We will examine the effect of direct exposure to whole bacteria, micro-vesicles and secreted products. In addition to assessing changes in mediator release and migration we will also investigate potential switching of mast cells to a regulatory phenotype. A combination of pharmacological approaches, mast cells from transgenics and electrophysiology will be employed to identify receptors, ion channels and pathways involved in transducing mast cell responses to bacteria signals.******Outcomes: Completion of the proposed studies will provide us with a deeper understanding of the interactions between mammals and bacteria that extends beyond the traditional view of innate immunity. In addition to the identification of novel modes of inter-kingdom communication this study will provide insight into how symbiotic relationships shape mammalian physiology. As such this is foundational research with potentially wide-reaching implications for biological sciences. **