南方医科大学学报 ›› 2021, Vol. 41 ›› Issue (7): 972-979.doi: 10.12122/j.issn.1673-4254.2021.07.02

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巨噬细胞移动抑制因子介导MPP+/MPTP诱导的小胶质细胞NLRP3炎症小体的激活

黄河灵,高玉元,聂 坤,王丽娟   

  • 出版日期:2021-07-20 发布日期:2021-07-17

Macrophage migration inhibitory factor meditates MPP+/MPTP-induced NLRP3 inflammasome activation in microglia cells

  • Online:2021-07-20 Published:2021-07-17

摘要: 目的 探讨巨噬细胞移动抑制因子(MIF)/κb(NF-κB)对1-甲基-4-苯基吡啶离子(MPP+)/1-甲基-4-苯基-1,2,3,6-四氢吡啶(MPTP)激活小胶质细胞NLRP3炎症小体的影响和机制,进而对神经元的影响。方法 慢病毒MIF-shRNA感染Bv-2细 胞,敲低MIF表达。Western blot检测MPP+干预的Bv-2 NLRP3和MIF表达水平、转染病毒后细胞NLRP3、p65、caspase-1表达水平及细胞核、浆蛋白p65表达水平。ELISA检测细胞培养上清液IL-1β、IL-18表达水平。将细胞培养上清液作为条件培养基培养MN9D细胞,Western blot检测TH蛋白表达水平。C57BL/6小鼠腹腔注射MPTP构建PD小鼠模型,向中脑黑质致密部立体定位注射腺相关病毒MIF-shRNA(AAV-MIF-shRNA)敲低MIF表达。对小鼠进行旷场实验、爬杆实验、悬挂实验行为学评估,组织免疫组化检测小鼠多巴胺能神经元细胞数目和小胶质细胞活化情况,Western blot 检测小鼠黑质 MIF、NLRP3及TH表达情况。结果 感染病毒的细胞MIF mRNA(P<0.001)和MIF蛋白(P=0.014)明显降低。Western blot显示,0.2 mmol MPP+使Bv-2细胞NLRP3(P=0.012)和MIF(P=0.019)表达增高。与MPP组比较,MIF-shRNA组NLRP3(P=0.042) 和caspase-1(P=0.003)表达减少,细胞总蛋白中p65表达没有差异(P=0.978)。ELISA检测细胞上清液发现MIF-shRNA组较MPP组IL-1β(P<0.001)、IL-18(P=0.002)水平降低。与MPP组比较,MIF-shRNA组核蛋白p65表达降低(P=0.016),浆蛋白p65表达升高(P<0.001)。相较于MPP+的条件培养基,MN9D细胞在MIF-shRNA条件培养基中TH(P=0.01)表达增加。与MPTP 组比较,注射 MIF-shRNA 的小鼠爬杆实验(P=0.024)和旷场实验(P=0.026)评分显著降低,悬挂实验评分显著升高(P=0.001)。组织免疫组化结果显示,相较于MPTP组,AAV-MIF-shRNA组小鼠TH阳性神经元细胞数量增多(P=0.004),小胶质细胞数量减少(P=0.049)。MIF(P=0.033)、NLRP3表达减少(P=0.045),TH蛋白明显增多(P=0.043)。结论 抑制MIF表达可以减少MPP+/MPTP干预所引起的小胶质细胞NLRP3炎症小体表达和炎症因子释放,减轻小胶质细胞激活,减轻炎症反应,改善MPTP引起的黑质多巴胺能神经元损伤,在帕金森病神经炎症方面具有保护作用。

关键词: 帕金森病;神经炎症;巨噬细胞移动抑制因子;NLRP3炎症小体;小胶质细胞

Abstract: Objective To explore the mechanisms of macrophage migration inhibitory factor (MIF)/nucleus factor-κB (NF-κB) in mediating 1-methyl-4-phenylpyridinium iodide (MPP + )/1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced activation of Nod-like receptor protein 3 (NLRP3) inflammasome in microglials and the its effects on neurons. Methods Murine microglial cell line Bv-2 was infected with a lentivirus carrying MIF shRNA for MIF knockdown and then treated with MPP+. The total protein levels of NLRP3, caspase-1, p65 and p65 in the cell nuclei and cytoplasm were detected. ELISA was used to detect the levels of IL-1β and IL-18 in the culture supernatant, which served as the conditioned culture medium for MN9D cells, whose TH expression level was detected using Western blotting. The effect of stereotactic injection of an adeno-associated virus (AAV) carrying MIF shRNA on behaviors was assessed in a C57BL/6 mouse model of Parkinson disease (PD) induced by intraperitoneal MPTP injection. TH and Iba-1 immunohistochemistry was used to evaluate the number of substantia nigraneurons and the activation of microglia cells, and the protein expressions of MIF, NLRP3 and TH in the substantia nigra were detected with Western blotting. Results MPP+ significantly increased NLRP3 and MIF expressions in Bv-2 cells (P<0.05). MIF knockdown in Bv-2 cells significantly lowered NLRP3 and caspase-1 protein expressions and IL-1β and IL-18 levels in the culture supernatant (P<0.05) without affecting total protein level of p65. Bv-2 cells with MIF knockdown showed significantly lowered p65 protein expression in the nuclei but increased p65 expression in the cytoplasm (P<0.05). The conditioned medium derived from Bv-2 cells with MIF knockdown, as compared with that from than MPP +-treated Bv-2 cells, significantly increased TH expression in MN9D cells (P=0.01). Compared with those in MPTP group, the mice receiving injections of AAV-MIF-shRNA had higher scores in pole test and open field test with lower scores in traction test, and showed increased TH-positive neurons, decreased Iba-1 microglia cell activation, reduced expressions of MIF and NLRP3, and increased expression of TH in the substantia nigra (all P<0.05). Conclusion Inhibition of MIF can reduce the expression of NLRP3 inflammasomes and inflammatory factor caused by MPP+ in microglia cells to relieve the damage of dopaminergic neurons and alleviate microglia cell activation, thus offering protection against neuroinflammation in Parkinson's disease.

Key words: Parkinson's disease; neuroinflammation; macrophage migration inhibitory factor; Nod-like receptor protein 3 inflammasome; microglia cells