美国圣路易斯华盛顿大学医学院Marco Colonna和Simone Brioschi共同合作，近期取得重要工作进展。他们研究利用胚胎来源的脑巨噬细胞特异性Cre-deleter揭示小胶质细胞和边缘巨噬细胞的不同特征。相关研究成果2023年2月14日在线发表于《免疫》杂志上。

据介绍，从胚胎发育的早期阶段就缺乏特异性靶向小胶质细胞的遗传工具。

研究人员生成了一个由小胶质细胞标记基因Crybb1控制的组成型Cre系，该基因在围产期在胚胎脑巨噬细胞（小胶质细胞和边界相关巨噬细胞[BAM]）中产生了几乎完全的重组，在外周髓细胞中产生了有限的重组。使用该工具结合Flt3-Cre谱系示踪剂、单细胞RNA测序分析和共聚焦成像，研究人员在小鼠皮层中分辨出胚胎来源的BAM和单核来源的BAM。使用Crybb1-Cre删除小胶质细胞和胚胎来源BAM中的转录因子SMAD4导致小胶质细胞发育停滞。相比之下，真正的BAM的发育仍然没有受到影响。

总之，这一研究结果表明，SMAD4驱动一种转录和表观遗传程序，这对于脑巨噬细胞参与小胶质细胞的命运至关重要，并突出了Crybb1-Cre作为靶向胚胎脑巨噬细胞的工具。

附：英文原文

Title: A Cre-deleter specific for embryo-derived brain macrophages reveals distinct features of microglia and border macrophages

Author: Simone Brioschi, Julia A. Belk, Vincent Peng, Martina Molgora, Patrick Fernandes Rodrigues, Khai M. Nguyen, Shoutang Wang, Siling Du, Wei-Le Wang, Gary E. Grajales-Reyes, Jennifer M. Ponce, Carla M. Yuede, Qingyun Li, John M. Baer, David G. DeNardo, Susan Gilfillan, Marina Cella, Ansuman T. Satpathy, Marco Colonna

Issue&Volume: 2023-02-14

Abstract: Genetic tools to target microglia specifically and efficiently from the early stagesof embryonic development are lacking. We generated a constitutive Cre line controlledby the microglia signature gene Crybb1 that produced nearly complete recombination in embryonic brain macrophages (microgliaand border-associated macrophages [BAMs]) by the perinatal period, with limited recombinationin peripheral myeloid cells. Using this tool in combination with Flt3-Cre lineage tracer, single-cell RNA-sequencing analysis, and confocal imaging, we resolvedembryonic-derived versus monocyte-derived BAMs in the mouse cortex. Deletion of thetranscription factor SMAD4 in microglia and embryonic-derived BAMs using Crybb1-Cre caused a developmental arrest of microglia, which instead acquired a BAM specificationsignature. By contrast, the development of genuine BAMs remained unaffected. Our resultsreveal that SMAD4 drives a transcriptional and epigenetic program that is indispensablefor the commitment of brain macrophages to the microglia fate and highlight Crybb1-Cre as a tool for targeting embryonic brain macrophages.

DOI: 10.1016/j.immuni.2023.01.028

Source: https://www.cell.com/immunity/fulltext/S1074-7613(23)00040-7