Zhang Qianye, Zheng Mingxiao, Sun Wei, Loers Gabriele, Wen Min, Wang Qingpeng, Zheng Xuexing, Siebert Hans-Christian, Zhang Ruiyan, Zhang Ning
Institute of Biopharmaceutical Research, Liaocheng University, Liaocheng, Shandong 252000, China.
Center for Molecular Neurobiology Hamburg, University Medical Center, Hamburg-Eppendorf, University of Hamburg, Falkenried 94, 20251 Hamburg, Germany.
Food Funct. 2025 Jun 16;16(12):4731-4753. doi: 10.1039/d5fo00422e.
The activation of microglia is an important cause of central nervous system (CNS) inflammatory cell infiltration and inflammatory demyelination in multiple sclerosis (MS). NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome-mediated signaling plays a decisive role in microglial activation. Mitophagy is closely related to NLRP3-mediated neuroinflammation. Previous studies have shown that ketogenic diet (KD) suppresses microglial NLRP3 inflammasome activation and exerts mitophagy-stimulating effects, but the specific mechanism remains unclear. The current study examined the mechanism underlying the anti-inflammatory effect of KD on experimental autoimmune encephalomyelitis (EAE). Our data show that KD inhibited demyelination, increased co-staining of the translocase of the outer mitochondrial membrane (TOM20) and microtubule-associated protein 1A/1B-light chain 3 (LC3II), and decreased microglial NLRP3 inflammasome activation and histone deacetylase 3 (HDAC3) in the hippocampus of EAE mice. Further correlation analysis showed that the reduction of HDAC3 was negatively correlated with NLRP3 activation and positively correlated with the induction of mitophagy in KD-fed EAE mice. In BV2 microglial cells, we confirmed that the inhibition of HDAC3 promoted 5' adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR)/unc-51-like autophagy activating kinase (ULK)1 and PTEN-induced putative kinase 1 (PINK1)/Parkin-meditated mitophagy, which led to the up-regulation of acetylated AMPK, acetylated ULK1 and acetylated Parkin, and subsequently reduced ROS accumulation and inhibited the activation of the NLRP3 inflammasome. In addition, treatment with 3-methyladenine (3-MA), a specific autophagy inhibitor, abolished the anti-inflammatory effect of HDAC3 inhibition in BV2 cells. The study illustrates that KD ameliorates EAE by reducing NLRP3-mediated inflammation in microglial cells HDAC3 inhibition and enhancement of mitophagy-related protein acetylation.
小胶质细胞的激活是多发性硬化症（MS）中枢神经系统（CNS）炎性细胞浸润和炎性脱髓鞘的重要原因。含核苷酸结合寡聚化结构域样受体蛋白3（NLRP3）炎性小体介导的信号传导在小胶质细胞激活中起决定性作用。线粒体自噬与NLRP3介导的神经炎症密切相关。先前的研究表明，生酮饮食（KD）可抑制小胶质细胞NLRP3炎性小体的激活并发挥刺激线粒体自噬的作用，但其具体机制仍不清楚。本研究探讨了KD对实验性自身免疫性脑脊髓炎（EAE）抗炎作用的潜在机制。我们的数据表明，KD可抑制EAE小鼠海马体中的脱髓鞘，增加线粒体外膜转位酶（TOM20）与微管相关蛋白1A/1B轻链3（LC3II）的共染色，并降低小胶质细胞NLRP3炎性小体的激活以及组蛋白去乙酰化酶3（HDAC3）水平。进一步的相关性分析表明，在喂食KD的EAE小鼠中，HDAC3的减少与NLRP3激活呈负相关，与线粒体自噬的诱导呈正相关。在BV2小胶质细胞中，我们证实抑制HDAC3可促进5'-腺苷单磷酸激活的蛋白激酶（AMPK）/雷帕霉素靶蛋白（mTOR）/unc-51样自噬激活激酶（ULK）1以及PTEN诱导的假定激酶1（PINK1）/Parkin介导的线粒体自噬，这导致乙酰化AMPK、乙酰化ULK1和乙酰化Parkin上调，随后减少活性氧积累并抑制NLRP3炎性小体的激活。此外，用特异性自噬抑制剂3-甲基腺嘌呤（3-MA）处理可消除HDAC3抑制在BV2细胞中的抗炎作用。该研究表明，KD通过降低小胶质细胞中NLRP3介导的炎症、抑制HDAC3并增强与线粒体自噬相关蛋白的乙酰化来改善EAE。
