Brain development is a non-linear process of regionally specific epochs occurring during windows of sensitivity to endogenous and exogenous stimuli. We have identified an epoch in the neonatal rat brain defined by a transient population of peri-hippocampal mast cells (phMCs) that are abundant from birth through 2-weeks post-natal but absent thereafter. The phMCs are maintained by proliferation and harbor a unique transcriptome compared with mast cells residing in the skin, bone marrow, or other brain regions. Pharmacological activation of this population broadly increases blood-brain barrier permeability, recruits peripheral immune cells, and stunts local microglia proliferation. Examination of the post-mortem human brain demonstrated mast cells in the peri-hippocampal region of a newborn, but not an older infant, suggesting a similar developmental period exists in humans. Mast cells specifically, and early-life inflammation generally, have been linked to heightened risk for neurodevelopmental disorders, and these results demonstrate a plausible source of that risk.

中文翻译：

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肥大细胞在早期发育过程中在海马周围间隙增殖，并调节局部和外周免疫细胞


大脑发育是一个非线性过程，区域特异性时期发生在对内源性和外源性刺激敏感的窗口期间。我们已经在新生大鼠大脑中确定了一个时期，其定义为海马周围肥大细胞 （phMCs） 的瞬时群体，这些细胞从出生到出生后 2 周都很丰富，但此后不存在。phMC 通过增殖来维持，与驻留在皮肤、骨髓或其他大脑区域的肥大细胞相比，具有独特的转录组。该群体的药理学激活广泛增加血脑屏障通透性，募集外周免疫细胞，并阻碍局部小胶质细胞增殖。对死后人脑的检查显示，新生儿海马周围区域有肥大细胞，但年龄较大的婴儿没有，这表明人类也存在类似的发育期。特别是肥大细胞，以及一般的早期炎症，与神经发育障碍的风险增加有关，这些结果表明了这种风险的合理来源。