Microglial TLR4-dependent autophagy induces ischemic white matter damage via STAT1/6 pathway
Microglial TLR4-dependent autophagy induces ischemic white matter damage via STAT1/6 pathway
复制标题
小胶质细胞 TLR4 依赖性自噬通过 STAT1/6 途径诱导缺血性白质损伤。
DOI：
10.7150/thno.27882
复制
发表时间：
2018-01-01
期刊：
影响因子：
12.4
通讯作者：
Wang, Wei
中科院分区：
文献类型：
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作者：
Qin, Chuan;Liu, Qian;Wang, Wei
原理：缺血性白质损伤常导致髓磷脂丢失，并伴有小胶质细胞激活。我们之前发现，引导小胶质细胞向抗炎表型提供了一个有益的微环境，并有助于在慢性脑灌注不足期间维持白质完整性。然而，小胶质细胞极化的分子机制仍然难以捉摸。方法：建立低灌注诱导的白质损伤小鼠模型和脂多糖诱导的原代培养小胶质细胞。采用免疫荧光、Western blot和电镜观察小胶质细胞自噬激活情况。给药自噬抑制剂/激动剂来研究自噬过程在调节小胶质细胞表型中的作用。采用定量实时聚合酶链反应和Western blot检测可能的途径。结果：我们发现暴露于LPS的原代培养的小胶质细胞和激活的小胶质细胞在白质缺血性损伤期间的自噬体快速积累。自噬抑制剂将小胶质细胞功能从促炎表型转变为抗炎表型。此外，我们发现TLR4作为结合LPS的主要受体之一，在白质缺血性损伤时在胼胝体小胶质细胞上的表达最高，TLR4缺失可以模拟小胶质细胞功能转化的现象，并在慢性脑灌注不足时表现出保护作用。而TLR4缺乏组小胶质细胞的抗炎表型通过自噬过程的激活而基本被消除。最后，我们的转录分析证实，在LPS暴露的小胶质细胞中，STAT1的上调和STAT6的下调可以通过自噬抑制来逆转。结论：tlr4依赖性自噬调节小胶质细胞极化，通过STAT1/6通路诱导缺血性白质损伤。
Rationale: lschemic white matter damage frequently results in myelin loss, accompanied with microglial activation. We previously found that directing microglia towards an anti-inflammatory phenotype provided a beneficial microenvironment and helped maintain white matter integrity during chronic cerebral hypoperfusion. However, the molecular mechanisms underlying microglial polarization remain elusive.Methods: Hypoperfusion induced white matter damage mice model and lipopolysaccharide (LPS) induced primary cultured microglia were established. Autophagy activation in microglia was detected both in vivo and in vitro by immunofluorescence, Western blot and electron microscopy. Autophagy inhibitors/agonist were administrated to investigate the role of autophagic process in modulating microglial phenotypes. Quantitative real time-polymerase chain reaction and Western blot were carried out to investigate the possible pathway.Results: We identified rapid accumulation of autophagosomes in primary cultured microglia exposed to LPS and within activated microglia during white matter ischemic damage. Autophagy inhibitors switched microglial function from pro-inflammatory to anti-inflammatory phenotype. Furthermore, we found TLR4, one of the major receptors binding LPS, was most highly expressed on microglia in corpus callosum during white matter ischemic damage, and TLR4 deficiency could mimic the phenomenon in microglial functional transformation, and exhibit a protective activity in chronic cerebral hypoperfusion. Whereas, the anti-inflammatory phenotype of microglia in TLR4 deficiency group was largely abolished by the activation of autophagic process. Finally, our transcriptional analysis confirmed that the up-regulation of STAT1 and down-regulation of STAT6 in microglia exposure to LPS could be reversed by autophagy inhibition.Conclusion: These results indicated that TLR4-dependent autophagy regulates microglial polarization and induces ischemic white matter damage via STAT1/6 pathway.