AIMS Blood-borne monocytes/macrophages infiltrate the brain in massive numbers after ischemic stroke, but their impact on poststroke brain injury and recovery remains elusive. This study examined the transcriptomic changes in monocytes/macrophages after ischemic stroke and the functional implications of these changes, particularly with regards to the contribution of these cells to the phagocytic clearance of dead/dying cells (efferocytosis) in the poststroke brain. METHODS We performed whole-genome RNA sequencing on the monocyte/macrophage population sorted from mouse brain and peripheral blood 5 days after permanent focal cerebral ischemia. In addition, the spatial and temporal profiles of macrophage efferocytosis were examined in vivo by immunohistochemistry 3-7 days after brain ischemia. RESULTS Robust transcriptomic changes occurred in monocytes/macrophages upon infiltrating the poststroke brain. Functional enrichment analysis revealed a transcriptome of brain macrophages that strongly favored efferocytic activity. A large number of efferocytosis-related genes were upregulated in brain macrophages, the products of which are essential components involved in various steps of efferocytosis, such as chemotaxis, recognition of dead cells, engulfment, and processing of phagosomes. The efferocytic activity of brain macrophages were verified by immunohistochemistry, wherein Iba1-labeled microglia/macrophages effectively cleared apoptotic neurons in the infarct during the subacute stage after brain ischemia. We also identified PPARγ and STAT6 as potential upstream regulators that shaped this proefferocytic and inflammation-resolving transcriptome of macrophages in the poststroke brain. CONCLUSION Macrophages play a crucial role in the phagocytic clearance of dead neurons after ischemic stroke and promote the resolution of inflammation in the brain. Molecular therapies that enhance macrophage efferocytic capability may be promising treatments for ischemic stroke by facilitating inflammation resolution, brain repair, and recovery of neurological functions.

中文翻译：

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巨噬细胞在缺血性中风后重新编程并促进小鼠大脑中的细胞增多症和炎症消退。

AIMS 血源性单核细胞/巨噬细胞在缺血性中风后大量渗入大脑，但它们对中风后脑损伤和恢复的影响仍然难以捉摸。本研究检查了缺血性中风后单核细胞/巨噬细胞的转录组变化以及这些变化的功能意义，特别是关于这些细胞对中风后脑中死亡/垂死细胞的吞噬清除（胞吐作用）的贡献。方法 我们对永久性局灶性脑缺血 5 天后从小鼠脑和外周血中分选的单核细胞/巨噬细胞群进行全基因组 RNA 测序。此外，在脑缺血后 3-7 天，通过免疫组织化学在体内检查了巨噬细胞 efferocytosis 的空间和时间分布。结果 在浸润中风后脑部后，单核细胞/巨噬细胞发生了强烈的转录组变化。功能富集分析揭示了强烈支持 efferocytic 活动的脑巨噬细胞转录组。脑巨噬细胞中大量的胞吐作用相关基因上调，其产物是参与胞吐作用各个步骤的重要成分，如趋化性、死细胞识别、吞噬和吞噬体的加工。通过免疫组织化学验证了脑巨噬细胞的细胞活性，其中Iba1标记的小胶质细胞/巨噬细胞在脑缺血后的亚急性阶段有效清除了梗塞中的凋亡神经元。我们还将 PPARγ 和 STAT6 确定为潜在的上游调节因子，它们在中风后大脑中塑造了这种前细胞和炎症解决巨噬细胞的转录组。结论 巨噬细胞在缺血性卒中后吞噬清除死亡神经元和促进脑内炎症消退中起关键作用。通过促进炎症消退、大脑修复和神经功能恢复，增强巨噬细胞 efferocytic 能力的分子疗法可能是缺血性中风的有希望的治疗方法。