Quantitative and qualitative contribution of splenic monocytes to plaque development

动脉粥样硬化是一种慢性炎症性疾病，其中特别是单核细胞起着至关重要的作用。它们渗入斑块，分化成巨噬细胞和树突状细胞，并促进动脉粥样硬化从开始到并发症的所有阶段。直到最近，单核细胞被认为仅仅是短暂的细胞，从血液渗出到发炎组织中分化成局部效应细胞。然而，令人惊讶的是，Swirski等人最近发现，未分化的单核细胞积聚并驻留在脾脏中。在急性心肌梗死中，脾单核细胞大量浸润缺血区域并促进心肌损伤。这项科学基金申请旨在通过解决以下问题来探索脾单核细胞在动脉粥样硬化形成中的特定作用：1。浸润动脉粥样硬化斑块的单核细胞有多大比例来自脾脏？2.小鼠动脉粥样硬化中的脾单核细胞与骨髓释放的循环单核细胞功能不同吗？3.脾单核细胞是否最终和明确地调节斑块进展和斑块稳定性？我们提出了两种互补的方法。我们比较了脾切除ApoE-/-小鼠与相应对照组的动脉粥样硬化斑块。其次，将CD45.2+供体脾移植到CD45.1+受体中，以追踪CD45.2+脾单核细胞的斑块浸润以及它们在不同时间点分化成巨噬细胞和树突状细胞。这将使我们能够评估脾单核细胞对斑块组成的影响。方法包括经典的细胞和分子生物学工具和体内非侵入性成像技术。该提案的目标是更好地了解动脉粥样硬化背景下的单核细胞生物学，最终为开发新的治疗方法铺平道路。

Atherosclerosis is a chronic inflammatory disease in which particularly monocytes play a crucial role. They infiltrate plaques, differentiate into macrophages and dendritic cells and promote all stages of atherosclerosis from initiation to complication. Until recently monocytes were regarded as mere transitory cells, that extravasate from blood into inflamed tissue to differentiate into local effector cells. Surprisingly, however, Swirski et al. recently showed, that undifferentiated monocytes accumulate and reside in the spleen. In acute myocardial infarction splenic monocytes infiltrate the ischemic regions substantially and contribute to myocardial damage. This scientific grant application aims to explore the specific role of splenic monocytes in atherogenesis by addressing the following questions: 1. Which percentage of monocytes infiltrating atherosclerotic plaques originates from the spleen? 2. Are splenic monocytes in murine atherosclerosis functionally distinct from circulating monocytes released from the bone marrow? 3. Do splenic monocytes ultimatively and distinctly modulate plaque progression and plaque stability? We propose two complementary approaches. We compare atherosclerotic aortas from splenectomized ApoE-/- mice with respective controls. Secondly, CD45.2+ donor spleens are transplanted into CD45.1+ recipients in order to track plaque infiltration of CD45.2+ splenic monocytes as well as their differentiation into macrophages and dendritic cells at different time points. This will allow us to evaluate the influence of splenic monocytes on plaque composition. Methods include classical cell and molecular biology tools and non-invasive imaging techniques in vivo. The goal of this proposal is to gain a better understanding of monocyte biology in the context of atherosclerosis, ultimately paving the way for the development of novel therapeutic approaches.