Wu Chih-Cheng, Tzeng Chung-Yuh, Chang Cheng-Yi, Wang Jiaan-Der, Chen Yu-Fang, Chen Wen-Ying, Kuan Yu-Hsiang, Liao Su-Lan, Wang Wen-Yi, Chen Chun-Jung
Department of Anesthesiology, Taichung Veterans General Hospital, Taichung City, 407, Taiwan; Department of Financial Engineering, Providence University, Taichung City, 433, Taiwan; Department of Data Science and Big Data Analytics, Providence University, Taichung City, 433, Taiwan.
Department of Orthopedics, Taichung Veterans General Hospital, Taichung City, 407, Taiwan; Department of Medicinal Botanicals and Health Applications, Da-Yeh University, Changhua, 515, Taiwan.
Eur J Pharmacol. 2023 Sep 15;955:175927. doi: 10.1016/j.ejphar.2023.175927. Epub 2023 Jul 20.
Microglia have both protective and pathogenic properties, while polarization plays a decisive role in their functional diversity. Apart from being an energetic organelle, mitochondria possess biological capabilities of signaling and immunity involving mitochondrial dynamics. The N-methyl-D-aspartate (NMDA)-type glutamate receptor displays excitatory neurotransmission, excitatory neurotoxicity and pro-inflammatory properties in a membrane location- and cell context-dependent manner. In this study, we have provided experimental evidence showing that by acting on mitochondrial dynamics, NMDA receptors displayed pro-inflammatory properties, while its non-competitive inhibitor MK801 exhibited anti-inflammatory potential in Lipopolysaccharide (LPS)-challenged BV-2 microglia cells. LPS stimulation increased the protein phosphorylation of cells regarding their NMDA receptor component subunits and Calcium/Calmodulin-dependent Protein Kinase II (CaMKII), along with mobilizing intracellular calcium. Additionally, parallel changes occurred in the activation of Transforming Growth Factor-β (TGF-β)-Activated Kinase 1 (TAK1), NF-κB p65 and NF-κB DNA binding activity, acquisition of pro-inflammatory M1 polarization and expression of pro-inflammatory cytokines. LPS-treated cells further displayed signs of mitochondrial dysfunction with higher expressions of the active form of Dynamin-Related Protein 1 (Drp1), NADPH Oxidase-2 (NOX2) expression and the generation of DCFDA-/MitoSOX-sensitive Reactive Oxygen Species (ROS). NMDA receptor blockade by MK801, along with CaMKII inhibitor KN93, Drp1 inhibitor Mdivi-1 and antioxidant apocynin alleviated LPS-induced pro-inflammatory changes. Other than the reported CaMKII/TAK1/NF-κB axis, our in vitro study revealed the CaMKII/Drp1/ROS/NF-κB axis being an alternative cascade for shaping pro-inflammatory phenotypes of microglia upon LPS stimulation, and MK801 having the potential for inhibiting microglia activation and any associated inflammatory damages.
小胶质细胞具有保护和致病特性，而极化在其功能多样性中起决定性作用。线粒体除了是一个能量细胞器外，还具有涉及线粒体动力学的信号传导和免疫生物学能力。N-甲基-D-天冬氨酸（NMDA）型谷氨酸受体以膜定位和细胞环境依赖的方式表现出兴奋性神经传递、兴奋性神经毒性和促炎特性。在本研究中，我们提供了实验证据表明，通过作用于线粒体动力学，NMDA受体表现出促炎特性，而其非竞争性抑制剂MK801在脂多糖（LPS）刺激的BV-2小胶质细胞中表现出抗炎潜力。LPS刺激增加了细胞中NMDA受体组成亚基和钙/钙调蛋白依赖性蛋白激酶II（CaMKII）的蛋白磷酸化，同时动员了细胞内钙。此外，转化生长因子-β（TGF-β）激活激酶1（TAK1）、NF-κB p65的激活以及NF-κB DNA结合活性、促炎M1极化的获得和促炎细胞因子的表达也发生了平行变化。LPS处理的细胞进一步表现出线粒体功能障碍的迹象，动力相关蛋白1（Drp1）活性形式的表达更高、NADPH氧化酶-2（NOX2）表达以及DCFDA-/MitoSOX敏感的活性氧（ROS）的产生。MK801阻断NMDA受体，以及CaMKII抑制剂KN93、Drp1抑制剂Mdivi-1和抗氧化剂载脂蛋白减轻了LPS诱导的促炎变化。除了报道的CaMKII/TAK1/NF-κB轴外，我们的体外研究还揭示了CaMKII/Drp1/ROS/NF-κB轴是LPS刺激后塑造小胶质细胞促炎表型的另一个级联反应，并且MK801具有抑制小胶质细胞激活和任何相关炎症损伤的潜力。
