Kinetics and Mechanisms of Steady-State Dendritic Cell Migration

树突状细胞（dc）是专业抗原呈递细胞，主要负责启动新的免疫或耐受反应。它们在先天免疫系统和适应性免疫系统之间起着至关重要的作用。炎症刺激可诱导DC从外周组织迁移到淋巴结，这一过程对于诱导免疫反应至关重要。然而，在稳态下，DC迁移是组成性的，并且在启动外周免疫耐受中起重要作用，这是预防有害炎症的关键过程。这在肠道中最为明显，外周耐受性的失败可导致炎症性肠病（IBD）或食物过敏的发展。令人惊讶的是，在稳态下控制DC迁移的机制以及由此产生的耐受性免疫反应在很大程度上是未知的。为了机械地剖析稳态直流迁移的过程，我们开发了一系列新颖的专用工具。假传入淋巴的管化将使我们能够在迁移过程中分离DCs，而一种新的转基因小鼠模型，CCR7-GFP报告细胞，使我们能够识别即将离开外周组织的DCs。此外，利用体内光转换，我们将能够跟踪和量化直流迁移。我们的初步结果表明，稳态肠DC迁移是一个高度动态的过程，导致肠引流淋巴结的迁移DC隔室几乎每24小时完全更新一次。这种显著的资源投资进一步强调了稳态直流迁移的重要性。此外，我们发现肠dc，在从组织出口之前的阶段，已经采用了一种独特的表型。表征这些初始变化将使我们能够剖析控制DC迁移过程的分子机制。在本提案中，我们的目标是：1)确定稳态直流生命周期动力学2)表征控制稳态直流迁移的分子机制。3)确定稳态迁移dc在LN中的命运、位置和作用。该项目将生成稳态直流迁移及其调控的综合模型。我们期望这种理解，除了描述一个主要的生物学过程外，还可能提供影响炎症性疾病治疗方法未来发展和设计的信息，特别是在肠道方面。

Dendritic cells (DCs) are professional antigen presenting cells primarily responsible for the initiation of new immune or tolerogenic responses. They act as a crucial link between the innate and adaptive immune systems. DC migration from peripheral tissues into lymph nodes can be induced by inflammatory stimuli and this process is crucial for the induction of immune responses. However, in steady-state, DC migration occurs constitutively and has an important role in the initiation of peripheral immunological tolerance - a process crucial for the prevention of deleterious inflammation. This is most notable in the intestine, where a failure of peripheral tolerance can lead to the development of inflammatory bowel diseases (IBD) or food allergy. Surprisingly, the mechanisms controlling DC migration in steady state and thereby tolerogenic immune responses are largely unknown.To mechanistically dissect the process of steady state DC migration, we developed a range of novel, dedicated tools. Cannulation of the pseudo-afferent lymph will allow us to isolate DCs in the process of migration, while a novel transgenic mouse model, the CCR7-GFP reporter, enables the identification of DCs which are about to exit peripheral tissues. In addition, using in vivo photoconversion, we will be able to track and quantify DC migration. Our initial results show that steady-state intestinal DC migration is a highly dynamic process which leads to the almost complete turnover of the migratory DC compartment in intestine-draining lymph nodes every 24h. This remarkable investment of resources further underlines the importance of steady-state DC migration. Furthermore, we found that intestinal DCs, in the stages immediately preceding egress from tissue, already adopt a distinct phenotype. Characterising these initial changes will enable us to dissect the molecular mechanisms controlling the process of DC migration. In this proposal we aim to: 1) Determine the kinetics of steady-state DC life cycle 2) Characterise the molecular mechanisms controlling steady-state DC migration. 3) Determine the fate, location and function of steady-state migrating DCs in the LN. This project will generate a comprehensive model of steady state DC migration and its regulation. We expect that such understanding, in addition to characterizing a major biological process, may provide information that will affect the future development and design of treatments for inflammatory diseases, particularly in the context of the intestinal tract.