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，尤其是单核细胞在其中起着至关重要的作用。它们渗透斑块，分化为巨噬细胞和树突状细胞，促进动脉粥样硬化从开始到并发症的所有阶段。直到最近，单核细胞还被认为是纯粹的暂时性细胞，从血液中渗出到炎症组织中，分化为局部效应细胞。然而，令人惊讶的是，Swirski等人。最近发现，未分化的单核细胞聚集并驻留在脾内。在急性心肌梗死中，脾单核细胞大量渗入缺血区，导致心肌损伤。这项科学拨款申请旨在通过解决以下问题来探讨脾单核细胞在动脉粥样硬化形成中的具体作用：1.动脉粥样硬化斑块中有多少百分比的单核细胞来自脾？2.小鼠动脉粥样硬化中的脾单核细胞与从骨髓中释放的循环单核细胞在功能上是否不同？3.脾单核细胞最终和明显地调节斑块进展和斑块稳定性吗？我们提出了两种互补的方法。我们将去脾ApoE-/-小鼠的动脉粥样硬化与各自的对照进行比较。其次，将CD45.2+供体脾移植到CD45.1+受体体内，观察CD45.2+脾单核细胞在不同时间点的斑块浸润情况以及向巨噬细胞和树突状细胞的分化情况。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。这项建议的目标是在动脉粥样硬化的背景下更好地了解单核细胞生物学，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.