miRNA-451/MIF通路介导脑微血管损伤及神经元变性在帕金森病认知障碍发生中的作用机制

Our previous studies indicated that white matter lesions were observed in Parkinson's disease (PD) patients and mouse models with cognitive impairment. Meanwhile, the presence of white matter lesions is associated with cerebral microvascular disease and hypoperfusion, but the molecular mechanism is still unclear. Macrophage migration inhibitory factor (MIF), a direct target of miR-451, is associated with microvascular diseases. Moreover, we found that MIF was upregulated in blood samples of PD patients with cognitive impairment as well as in brain tissues of vascular dementia rat model. Furthermore, we demonstrated that PD mouse models with cognitive impairment display cerebral microvascular injuries and neuronal degeneration. Accordingly, we assume that miR-451/MIF and its downstream signaling pathways may be involved in cerebral microvascular injury, hypoperfusion and neuronal degeneration, and finally lead to cognitive impairment in PD. This hypothesis will be tested by lentivirus transfection and stereotactic injection in vitro and in vivo, respectively. Roles of PI3K/AKT/mTOR pathway in cerebral microvascular injury and neuronal degeneration will be confirmed by overexpression or silencing of MIF through a lentivirus stratedgy in PD mouse models. Meanwhile, the effect of MIF on the neuronal degeneration will be verified in vitro. This project is intended to elucidate the molecular mechanism of miR-451/MIF pathway involved in cognitive impairment in PD and provide new ideas for early intervention and precision treatment of cognitive impairment in PD.

我们前期研究发现帕金森病（PD）认知障碍患者及小鼠存在脑白质损害，且与脑微血管病变和低灌注有关，但其分子机制不明。研究报道miR-451调控巨噬细胞移动抑制因子（MIF）参与微血管病变。前期研究中我们已证实认知障碍患者血清中及血管性痴呆大鼠脑组织中MIF高表达，且PD认知障碍小鼠存在脑微血管损伤和神经元变性。据此我们推测：miR-451通过靶向调控MIF及其下游信号通路作用于脑微血管损伤、神经元变性而参与PD认知障碍。为验证上述假说，本项目拟利用慢病毒转染技术和脑立体定向注射技术，分别从动物和细胞两个层面，研究MIF慢病毒沉默或过表达载体调控PI3K/AKT/mTOR通路在PD小鼠模型脑微血管损伤和神经元变性中的作用，并通过PD体外细胞模型验证miR-451/MIF对神经元变性的调控作用，从而揭示miR-451/MIF通路在PD认知障碍中的分子作用机制，为其早期预防和精准治疗提供新思路。

我们前期研究发现帕金森病（PD）认知障碍患者及小鼠存在脑白质损害，且与脑微血管病变和低灌注有关。研究报道miR-451调控巨噬细胞移动抑制因子（MIF）参与微血管病变。前期研究中我们已证实认知障碍患者血清中及血管性痴呆大鼠脑组织中MIF高表达，且PD认知障碍小鼠存在脑微血管损伤和神经元变性。据此我们推测：miR-451通过靶向调控MIF及其下游信号通路作用于脑微血管损伤、神经元变性而参与PD认知障碍。为验证上述假说，本研究（1）通过动物实验发现低灌注会加剧PD小鼠的认知障碍；进一步研究发现脑血流低灌注显著加剧PD模型鼠神经（纤维）损伤、加剧PD模型鼠血脑屏障损伤和脑毛细血管内皮细胞损伤、同时引起PD模型鼠血管周边小胶质细胞介导的神经炎症的激活。（2）PDCN和PD-MCI患者血浆外泌体中miRNA-451表达与正常对照组有差异，且PD-MCI组患者脑脊液中miRNA-451的下游分子MIF、炎症因子、神经元损伤相关因子表达升高，内皮细胞活化相关因子表达下降。（3）miRNA-451表达水平降低可显著减轻小鼠认知功能障碍，脑组织中miRNA-451降低后MIF mRNA表达水平上升，同时存在小胶质细胞激活减少，黑质部多巴胺能神经元受损减少，海马区神经元损伤较轻，中脑细胞凋亡减少，推测MIF可能具有一定神经保护作用，进而开展进一步研究。（4）急性或亚急性PD小鼠模型会引起MIF继发性表达增加；增加MIF表达可以改善小鼠认知功能，改善血管内皮细胞、神经元细胞存活和功能，减少神经炎症水平；（5）PD细胞模型中过表达MIF可以抑制SH-SY5Y在MPP+干预下炎症因子TNF-α表达而增加抗炎因子IL-10的表达，且可增加JC-1表达信号，上调自噬相关通路分子，减少细胞凋亡。上述结果提示miRNA-451/MIF通路介导的脑微血管损伤、神经元存活、自噬活化水平及神经炎症改变在PD及PD-MCI的发生发展中有重要作用，为早期预防和精准治疗PD认知障碍提供了新思路、新靶点。