Department of Anatomy, school of medicine, Tehran University of Medical Sciences, Tehran, Iran.
Department of Clinical Biochemistry, Tehran University of Medical Sciences, Tehran, Iran.
Neurotox Res. 2021 Dec;39(6):1732-1746. doi: 10.1007/s12640-021-00417-y. Epub 2021 Sep 27.
Multiple sclerosis (MS) is a chronic disorder characterized by reactive gliosis, inflammation, and demyelination. Microglia plays a crucial role in the pathogenesis of MS and has the dynamic plasticity to polarize between pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes. Metformin, a glucose-lowering drug, attenuates inflammatory responses by activating adenosine monophosphate protein kinase (AMPK) which suppresses nuclear factor kappa B (NF-κB). In this study, we indirectly investigated whether metformin therapy would regulate microglia activity in the cuprizone (CPZ)-induced demyelination mouse model of MS via measuring the markers associated with pro- and anti-inflammatory microglia. Evaluation of myelin by luxol fast blue staining revealed that metformin treatment (CPZ + Met) diminished demyelination, in comparison to CPZ mice. In addition, metformin therapy significantly alleviated reactive microgliosis and astrogliosis in the corpus callosum, as measured by Iba-1 and GFAP staining. Moreover, metformin treatment significantly downregulated the expression of pro-inflammatory associated genes (iNOS, H2-Aa, and TNF-α) in the corpus callosum, whereas expression of anti-inflammatory markers (Arg1, Mrc1, and IL10) was not promoted, compared to CPZ mice. Furthermore, protein levels of iNOS (pro-inflammatory marker) were significantly decreased in the metformin group, while those of Trem2 (anti-inflammatory marker) were increased. In addition, metformin significantly increased AMPK activation in CPZ mice. Finally, metformin administration significantly reduced the activation level of NF-κB in CPZ mice. In summary, our data revealed that metformin attenuated pro-inflammatory microglia markers through suppressing NF-κB activity. The positive effects of metformin on microglia and remyelination suggest that it could be used as a promising candidate to lessen the incidence of inflammatory neurodegenerative diseases such as MS.
多发性硬化症（MS）是一种以反应性神经胶质增生、炎症和脱髓鞘为特征的慢性疾病。小胶质细胞在 MS 的发病机制中起着至关重要的作用，具有从促炎（M1）表型向抗炎（M2）表型极化的动态可塑性。二甲双胍是一种降血糖药物，通过激活腺苷单磷酸蛋白激酶（AMPK）来抑制核因子 kappa B（NF-κB），从而减轻炎症反应。在这项研究中，我们通过测量与促炎和抗炎小胶质细胞相关的标志物，间接研究二甲双胍治疗是否会调节 CPZ 诱导的 MS 脱髓鞘小鼠模型中小胶质细胞的活性。通过卢索快速蓝染色评估髓鞘发现，与 CPZ 小鼠相比，二甲双胍治疗（CPZ+Met）可减少脱髓鞘。此外，与 CPZ 小鼠相比，二甲双胍治疗可显著减轻胼胝体中的反应性小胶质细胞和星形胶质细胞增生，这通过 Iba-1 和 GFAP 染色来测量。此外，与 CPZ 小鼠相比，二甲双胍治疗可显著下调胼胝体中促炎相关基因（iNOS、H2-Aa 和 TNF-α）的表达，而抗炎标志物（Arg1、Mrc1 和 IL10）的表达并未上调。此外，与 CPZ 组相比，二甲双胍组中 iNOS（促炎标志物）的蛋白水平显著降低，而 Trem2（抗炎标志物）的蛋白水平升高。此外，二甲双胍可显著增加 CPZ 小鼠中 AMPK 的激活。最后，二甲双胍给药可显著降低 CPZ 小鼠中 NF-κB 的激活水平。总之，我们的数据表明，二甲双胍通过抑制 NF-κB 活性来减弱促炎小胶质细胞标志物。二甲双胍对小胶质细胞和髓鞘再生的积极作用表明，它可能被用作减轻炎症性神经退行性疾病（如 MS）发病率的有前途的候选药物。
