Molecular mechanisms of a multi-tissue innate immune response

项目摘要/摘要 先天免疫是获得性免疫防御的第一道防线和引爆物。 感染，以及其过度长时间的激活会促进慢性炎症性疾病。而主要的 参与先天性免疫的分子参与者和信号通路已经被确定，更多的研究是 需要了解多个组织之间的信号如何触发先天免疫反应 生物体水平。由于研究脊椎动物的多组织先天免疫反应仍然具有挑战性 系统，我们用一个简单的无脊椎动物模型来解决这个问题。果蝇是黑腹果蝇的关键 先天免疫的发现，也同样被认为是理解分子的一个很好的模型 驱动更复杂、多组织的先天免疫反应的机制。具体来说，我们建议 研究一种新的成年果蝇先天免疫反应模型，它涉及到 免疫细胞(血细胞)、呼吸道上皮和解剖共定位区域的储存库 脂肪体内的免疫组织。在这个模型中，我们将重点放在Droocin作为读出的表达上，这是 促进细菌感染后的存活。我们发现血细胞，特别是它们通过NFkB发出的信号- 相关的IMD途径，是诱导呼吸道上皮Droocin表达所必需的，并 脂肪体的局部受限区域。然而，尽管血细胞中的IMD信号是必需的，但它并不是 足以触发Droocin反应。 我们假设免疫细胞充当细菌感染的哨兵，传递一个(目前尚不确定的)信号。 对呼吸道上皮和脂肪体的作用，从而上调Droocin。Droocin已经，在 内源性表达水平、抗菌功能和促进细菌感染后动物的存活。 我们建议(1)确定在其他组织中触发Droocin反应的血细胞信号/S，以及(2) 确定组织内传递Droocin反应的信号通路。 这项工作意义重大，因为来自这个果蝇模型的见解有望增加我们的 对驱动多种组织天然免疫反应的分子机制的了解 生物群，从而将“器官间/组织间交流”的概念扩展到先天 豁免权。在这个模型中发现的新的机械原理有望为脊椎动物的研究和 激发抑制或增强多组织先天免疫反应的治疗方法，这可能是 针对各种医疗需求和条件量身定做。

PROJECT SUMMARY/ABSTRACT Innate immunity plays important roles as first line defense and primer for adaptive immunity to protect against infection, and its excessive prolonged activation promotes chronic inflammatory diseases. While the main molecular players and signaling pathways involved in innate immunity have been identified, more research is needed to understand how signaling among multiple tissues triggers innate immune responses at the organismal level. Since studying multi-tissue innate immune responses remains challenging in vertebrate systems, we address this question in a simple invertebrate model. Drosophila melanogaster has been key in the discovery of innate immunity, and it is likewise expected to be an excellent model to understand molecular mechanisms that drive more complex, multi-tissue innate immune responses. Specifically, we propose to investigate a new model of an innate immune response in adult Drosophila, which involves the combination of a reservoir of immune cells (hemocytes), respiratory epithelium, and domains of the anatomically colocalizing immune tissue of the fat body. In this model, we focus on the expression of Drosocin as a readout, which promotes survival after bacterial infection. We find that hemocytes, and specifically their signaling by the NFkB- related Imd pathway, are required for the induction of Drosocin expression in the respiratory epithelium and locally restricted domains of the fat body. However, while Imd signaling in hemocytes is required, it is not sufficient to trigger the Drosocin response. We hypothesize that immune cells act as sentinels of bacterial infection that relay a (so far unidentified) signal to the respiratory epithelium and fat body, which in response upregulate Drosocin. Drosocin has, at endogenous expression levels, anti-bacterial function and promotes animal survival after bacterial infection. We propose to (1) identify hemocyte signal/s that trigger the Drosocin response in other tissues, and (2) identify the signaling pathways within tissues that relay the Drosocin response. This work is significant because insights from this Drosophila model are expected to increase our understanding of the molecular mechanisms that drive multi-tissue innate immune responses in a variety of organisms across phyla, thereby extending the concept of `inter-organ/-tissue communication' to innate immunity. New mechanistic principles identified in this model are expected to inform vertebrate research and inspire therapeutic approaches that curb or enhance multi-tissue innate immune responses, which could be tailored toward a variety of medical needs and conditions.