Active Extracellular Vesicles - defining a novel, extracellular metabolic compartment and its role in the control of inflammation.

炎症是免疫系统用来帮助保护免受感染和修复创伤造成的损伤的正常防御机制。然而，只有当反应被关闭并且感染或创伤组织恢复正常时，炎症的益处才会实现。这个过程被称为“解决”，并依赖于免疫细胞（已经完成了保护工作）被移除。为了去除它们，这些不需要的细胞死亡，并且当它们这样做时，它们释放出小的膜袋（称为细胞外囊泡：EV）。我们已经证明，这些EV是吸引“生物标记”细胞（“巨噬细胞”）的关键，这些细胞通过吞噬它们来清除垂死的细胞，并且至关重要的是，它们产生额外的信号来驱动组织修复。我们已经鉴定了一种促进巨噬细胞募集的分子，但这些EV促进巨噬细胞中“修复”反应的方式仍然未知。现在，我们的初步工作表明，这些EV携带一个活性酶家族，这将有助于产生小脂质分子，这些小脂质分子可能控制炎症和修复反应。本文提出的工作将定义这些活性酶的作用，这些活性酶从EV中的垂死细胞传递到巨噬细胞。因此，这些“活性”EV代表了一种新的细胞外代谢活性区室，能够将炎症控制信号传递给周围的细胞，如巨噬细胞。未能控制炎症反应可能导致慢性炎症和许多与衰老相关的炎症性疾病。因此，通过了解促进炎症的细胞与促进消退和修复的细胞之间的通信机制，我们将更清楚地了解炎症驱动的疾病（例如心血管疾病，癌症，神经退行性疾病）的可能治疗方法。此外，我们还将研究一系列已知有助于促进修复的其他细胞的EV。例如，一种干细胞，一种“MSC”，在再生医学方面有很大的希望，但最近从这些细胞中释放的EV被认为是活跃的，可以刺激“修复环境”。因此，我们将详细研究来自MSC的EV的炎症控制代谢活性。这增加了我们可能能够定义EV修复活性所需的关键因素的可能性，为再生医学开辟了新的基于干细胞或无细胞疗法。为了检验我们的核心假设，我们将从一系列垂死和活细胞中分析EV组成中是否存在酶、其底物及其产物。我们将测试电动汽车在体外和体内促进修复的能力，我们将抑制关键酶，以评估这种活性的基本性质。此外，我们将寻求“调整”或优化细胞培养条件，以最大限度地提高EV的生产和功能。这项工作将首次详细介绍炎症控制，代谢活性的细胞外室。它将在分子水平上定义垂死细胞如何与其他细胞沟通，以确保炎症得到控制。这一点很重要，因为对炎症的无效控制会导致疾病。因此，利用我们的工作将针对那些炎症有助于驱动疾病的情况，并将使新的策略能够促进自我修复。

Inflammation is a normal defence mechanism used by the immune system to help protect from infection and to repair damage caused by trauma. However, the benefits of inflammation are only realised when the response is turned off and the infected or traumatised tissue is returned to normal. This process is known as 'resolution' and relies on immune cells (that have done their protective job) being removed. To allow their removal, these unwanted cells die and, as they do so, they release small membrane bags (called extracellular vesicles: EV). We have shown that these EV are key to attracting 'undertaker' cells ('macrophages') that remove the dying cells by eating them and, crucially, they produce additional signals that drive the tissue to repair.Relatively little is known of how these EV function. We have identified a molecule that promotes recruitment of macrophages but the manner in which these EV promote 'repair' responses in macrophages remains unknown. Now, our preliminary work has shown that these EV carry a family of active enzymes which will help to produce small lipid molecules that may control inflammation and repair responses. The work proposed here will define the action of these active enzymes that are delivered from dying cells to macrophages in EV. As such, these 'active' EV represent a novel extracellular metabolically-active compartment capable of transmitting inflammation-controlling signals to surrounding cells such as macrophages.Why is this important? A failure to control inflammatory responses can lead to chronic inflammation and many of the inflammatory diseases associated with ageing. So, by understanding the mechanisms of communication between cells promoting inflammation, and those cells promoting resolution and repair, we will have a clearer insight to possible therapeutic approaches for diseases that are driven by inflammation (e.g. cardiovascular disease, cancer, neurodegeneration). Furthermore, we will study EV from a range of other cells that are known to help promote repair. For example, a type of stem cell, an 'MSC', has held great promise for regenerative medicine but recently the EV released from these cells have been proposed to be active to stimulate a 'repair environment'. Consequently, we will study in detail the inflammation-controlling metabolic activity of EV from MSC. This raises the possibility that we may be able to define the crucial factors required for EV repair activity, opening up novel stem cell-based or cell-free therapies for regenerative medicine. In order to test our core hypothesis, we will analyse, from a range of dying and viable cells, EV composition for the presence of enzymes, their substrates and their products. We will test the EVs' ability to promote repair in vitro and in vivo and we will inhibit the key enzymes to assess the essential nature of this activity. Furthermore, we will seek to 'tune' or refine cell culture conditions to maximise EV production and function.This work will, for the first time, detail an inflammation-controlling, metabolically-active extracellular compartment. It will define, at a molecular level, how dying cells communicate with other cells to ensure inflammation is controlled. This is important because ineffective control of inflammation leads to disease. Thus, exploitation of our work will target those conditions where inflammation helps drive disease and will enable novel strategies to promote self-repair.