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

背景和依据：肥大细胞长期以来被认为是人类过敏性疾病的关键效应器，现在被认为是先天性和适应性免疫应答的主要诱导剂和放大剂。它们在气道和肠粘膜中的大量存在表明它们作为重要的守门人/哨兵在这些入口处对抗感染性生物体的作用。然而，肥大细胞在防御病原体的前线的地位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方面发挥重要作用。 根据我们以前的研究，以及其他人的研究，似乎非致病性细菌可以利用不同的机制来稳定肥大细胞，通过直接的细胞-细胞相互作用，通过分泌介质，并可能通过释放膜微泡。我们还确定了肥大细胞上的受体和离子通道是新型细菌信号系统的潜在靶点。 目的：这项研究计划的长期目标是了解新的王国间通信系统的分子机制，并有助于我们了解这些系统在塑造细菌与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检查微生物介导的肥大细胞功能调节： ·确定各种非病原微生物、微生物脱落微泡和代谢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。 ·识别参与宿主/微生物相互作用的新方面的潜在肥大细胞受体。 实验方法：我们将重点关注乳酸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。我们将研究直接暴露于整个细菌，微泡和分泌产物的影响。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。将采用药理学方法、转基因肥大细胞和电生理学的组合来鉴定参与转导肥大细胞对细菌信号的反应的受体、离子通道和途径。 成果：完成拟议的研究将使我们更深入地了解哺乳动物和细菌之间的相互作用，超越传统的先天免疫观。除了识别新的王国间通信模式，这项研究将提供深入了解共生关系如何塑造哺乳动物的生理。因此，这是对生物科学具有潜在广泛影响的基础研究。

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.