Department of Forensic Medicine, Medical School of Soochow University, Suzhou, China.
J Neurochem. 2020 Jul;154(2):190-204. doi: 10.1111/jnc.14983. Epub 2020 Mar 3.
Neuroinflammation accompanied by microglial activation triggers multiple cell death after traumatic brain injury (TBI). The secondary injury caused by inflammation may persist for a long time. Recently, platelet C-type lectin-like 2 receptor (CLEC-2) has been shown to regulate inflammation in certain diseases. However, its possible effects on TBI remain poorly understood. Here, we aimed to investigate the role of platelet CLEC-2 in the pathological process of neuroinflammation after TBI. In this study, mice were subjected to sham or controlled cortical impact injury, and arbitrarily received recombinant platelet CLEC-2. In parallel, BV2 cells were treated with lipopolysaccharide (LPS) to mimic microglial activation after TBI. Primary endothelial cells were also subjected to LPS in order to replicate the inflammatory damage caused by TBI. We used western blot analysis, reverse transcription polymerase chain reaction (RT-PCR), and immunostaining to evaluate the role of platelet CLEC-2 in TBI. In conditional knock out platelet CLEC-2 mice, trauma worsened the integrity of the blood-brain barrier and amplified the release of inflammatory cytokines. In wild type mice subjected to controlled cortical impact injury, recombinant platelet CLEC-2 administration altered the secretion of inflammatory cytokines, reduced brain edema, and improved neurological function. In vitro, the polarization phenotype of microglia induced by LPS was transformed by recombinant platelet CLEC-2, and this conversion depended on the mammalian target of rapamycin (mTOR) pathway. Endothelial cell injury by LPS was ameliorated when microglia expressed mostly M2 phenotype markers. In conclusion, platelet CLEC-2 regulates trauma-induced neuroinflammation and restores blood-brain barrier integrity.
神经炎症伴小胶质细胞激活触发创伤性脑损伤（TBI）后的多种细胞死亡。炎症引起的继发性损伤可能持续很长时间。最近，血小板 C 型凝集素样 2 受体（CLEC-2）已被证明可调节某些疾病中的炎症。然而，其对 TBI 的可能影响仍知之甚少。在这里，我们旨在研究血小板 CLEC-2 在 TBI 后神经炎症病理过程中的作用。在这项研究中，小鼠接受假手术或皮质撞击伤，并任意接受重组血小板 CLEC-2。同时，BV2 细胞用脂多糖（LPS）处理以模拟 TBI 后的小胶质细胞激活。原代内皮细胞也用 LPS 处理，以复制 TBI 引起的炎症损伤。我们使用 Western blot 分析、逆转录聚合酶链反应（RT-PCR）和免疫染色来评估血小板 CLEC-2 在 TBI 中的作用。在条件敲除血小板 CLEC-2 小鼠中，创伤使血脑屏障的完整性恶化，并放大了炎症细胞因子的释放。在接受皮质撞击伤的野生型小鼠中，重组血小板 CLEC-2 给药改变了炎症细胞因子的分泌，减轻了脑水肿并改善了神经功能。在体外，LPS 诱导的小胶质细胞极化表型被重组血小板 CLEC-2 转化，这种转化依赖于哺乳动物雷帕霉素靶蛋白（mTOR）途径。当小胶质细胞表达主要为 M2 表型标志物时，LPS 引起的内皮细胞损伤得到改善。总之，血小板 CLEC-2 调节创伤引起的神经炎症并恢复血脑屏障的完整性。
