Wang Bo, Huang Xiao, Pan Xiao, Zhang Ting, Hou Cheng, Su Wen-Jun, Liu Lin-Lin, Li Jia-Mei, Wang Yun-Xia
Department of Nautical Psychology, Faculty of Psychology, Second Military Medical University, Shanghai 200433, China; Department of Stress Medicine, Faculty of Psychology, Second Military Medical University, Shanghai 200433, China; Department of Medicine, The Unit 31641 of PLA, Xishuangbanna 666100, China.
Department of Anaesthesiology, South Campus, Ren Ji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 201112, China.
Brain Behav Immun. 2020 Aug;88:132-143. doi: 10.1016/j.bbi.2020.06.019. Epub 2020 Jun 15.
Our previous study reports the causal role of high mobility group box 1 (HMGB1) in the development of depression; and we find glycyrrhizic acid (GZA) can be a potential treatment for major depressive disorder (MDD) considering its inhibition of HMGB1 activity. This study aims to further explore the exact cell types that release HMGB1 in the hippocampus.
We detected the effects of microglia conditioned medium on primary astrocytes and neurons. The effects of minocycline on depressive-like behaviors were tested in BABLB/c mice after four weeks of chronic unpredictable mild stress (CUMS) exposure. Furthermore, the immunofluorescence (IF) assays, hematoxylin-eosin (HE) and TUNEL staining were used to observe hippocampal slices to evaluate the release of HMGB1. The cytoplasmic translocations of HMGB1 protein were assayed by western-blot.
Exposure to CUMS caused an active release of HMGB1 from microglia and neurons in the hippocampus. After minocycline administration for inhibiting the activation of microglia, both microglia and neurons reduced the release of HMGB1 and the protein level of central and peripheral HMGB1 recovered accordingly. Along with blocking the release of HMGB1, behavioral and cognitive deficits induced by CUMS were improved significantly by minocycline. In addition, the supernatant of primary microglia stimulated the secretion of HMGB1 in primary neurons, not in astrocytes, at 24 h after 4 h-LPS treatment.
All the evidence supported our hypotheses that microglia and neurons are the main cell sources of HMGB1 release under CUMS condition, and that the release of HMGB1 by microglia may play an important role in the development of depressive-like behavior.
我们之前的研究报道了高迁移率族蛋白B1（HMGB1）在抑郁症发生中的因果作用；并且我们发现，考虑到甘草酸（GZA）对HMGB1活性的抑制作用，它可能是治疗重度抑郁症（MDD）的一种潜在药物。本研究旨在进一步探究海马体中释放HMGB1的确切细胞类型。
我们检测了小胶质细胞条件培养基对原代星形胶质细胞和神经元的影响。在BABLB/c小鼠接受四周慢性不可预测轻度应激（CUMS）后，测试米诺环素对抑郁样行为的影响。此外，采用免疫荧光（IF）检测、苏木精-伊红（HE）染色和TUNEL染色观察海马体切片，以评估HMGB1的释放情况。通过蛋白质免疫印迹法检测HMGB1蛋白的细胞质转位。
暴露于CUMS会导致海马体中的小胶质细胞和神经元主动释放HMGB1。在给予米诺环素抑制小胶质细胞的激活后，小胶质细胞和神经元均减少了HMGB1的释放，中枢和外周HMGB1的蛋白质水平也相应恢复。随着HMGB1释放的阻断，米诺环素显著改善了CUMS诱导的行为和认知缺陷。此外，在脂多糖（LPS）处理4小时后24小时，原代小胶质细胞的上清液刺激了原代神经元中HMGB1的分泌，而对星形胶质细胞无此作用。
所有证据均支持我们的假设，即在CUMS条件下，小胶质细胞和神经元是HMGB1释放的主要细胞来源，并且小胶质细胞释放HMGB1可能在抑郁样行为的发生中起重要作用。
