Embryonic microglia influence developing hypothalamic glial populations
Embryonic microglia influence developing hypothalamic glial populations
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DOI：
10.1186/s12974-020-01811-7
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发表时间：
2020-05-06
影响因子：
9.3
通讯作者：
Kurrasch, Deborah M.
中科院分区：
文献类型：
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作者：
Marsters, Candace M.;Nesan, Dinushan;Kurrasch, Deborah M.
背景虽然过去认为小胶质细胞在胎儿脑中是不成熟的，但这些免疫细胞与附近神经祖细胞之间有目的的相互作用的证据正在建立。在这里，我们研究了胚胎小胶质细胞对发育中的下丘脑结节内胶质细胞生成的影响，下丘脑结节是一个后来对能量平衡、生殖和体温调节很重要的区域。方法我们使用免疫组织化学来定量胚胎脑（E13.5-E17.5）中神经胶质细胞的位置和数量，以及药理学方法（即，PLX 5622）来敲低胎儿小胶质细胞。我们还进行了细胞因子和趋化因子分析的胚胎大脑中存在或不存在的小胶质细胞，和神经球测定，以测试改变细胞因子对下丘脑祖细胞行为的影响。结果我们鉴定了一个活化的小胶质细胞亚群，它们聚集在第三脑室附近，与胚胎Olig 2+神经祖细胞（NPC）一起，这些细胞注定会产生少突胶质细胞和星形胶质细胞。在没有小胶质细胞的情况下，我们观察到E17.5时留在心室的Olig 2+胶质祖细胞增加，同时这些Olig 2+细胞在套区减少，表明这些前体细胞迁移延迟。在没有小胶质细胞的情况下，对下丘脑灰质和白色区中成熟的少突胶质细胞的进一步检查揭示了在E17.5时灰质内的迁移的少突胶质细胞祖细胞（OPCs），此时OPCs开始减缓其迁移。最后，在离体E15.5下丘脑培养物+/-小胶质细胞中细胞因子和趋化因子信号传导的定量揭示了在不存在小胶质细胞的情况下几种细胞因子的蛋白质水平的降低。我们测定了两种下调的细胞因子（CCL 2和CXCL 10）对培养的下丘脑NPC的神经球形成能力和谱系承诺的影响，并显示NPC增殖以及神经元和少突胶质细胞分化的增加。结论小胶质细胞影响发育中下丘脑结节区胶质细胞的形成。
Background Although historically microglia were thought to be immature in the fetal brain, evidence of purposeful interactions between these immune cells and nearby neural progenitors is becoming established. Here, we examined the influence of embryonic microglia on gliogenesis within the developing tuberal hypothalamus, a region later important for energy balance, reproduction, and thermoregulation. Methods We used immunohistochemistry to quantify the location and numbers of glial cells in the embryonic brain (E13.5-E17.5), as well as a pharmacological approach (i.e., PLX5622) to knock down fetal microglia. We also conducted cytokine and chemokine analyses on embryonic brains in the presence or absence of microglia, and a neurosphere assay to test the effects of the altered cytokines on hypothalamic progenitor behaviors. Results We identified a subpopulation of activated microglia that congregated adjacent to the third ventricle alongside embryonic Olig2+ neural progenitor cells (NPCs) that are destined to give rise to oligodendrocyte and astrocyte populations. In the absence of microglia, we observed an increase in Olig2+ glial progenitor cells that remained at the ventricle by E17.5 and a concomitant decrease of these Olig2+ cells in the mantle zone, indicative of a delay in migration of these precursor cells. A further examination of maturing oligodendrocytes in the hypothalamic grey and white matter area in the absence of microglia revealed migrating oligodendrocyte progenitor cells (OPCs) within the grey matter at E17.5, a time point when OPCs begin to slow their migration. Finally, quantification of cytokine and chemokine signaling in ex vivo E15.5 hypothalamic cultures +/- microglia revealed decreases in the protein levels of several cytokines in the absence of microglia. We assayed the influence of two downregulated cytokines (CCL2 and CXCL10) on neurosphere-forming capacity and lineage commitment of hypothalamic NPCs in culture and showed an increase in NPC proliferation as well as neuronal and oligodendrocyte differentiation. Conclusion These data demonstrate that microglia influence gliogenesis in the developing tuberal hypothalamus.