Department of Neurology, First Hospital of Shanxi Medical University, Taiyuan, Shanxi, China.
First Clinical Medical College of Shanxi Medical University, Taiyuan, Shanxi, China.
Front Immunol. 2023 Jan 16;13:1021703. doi: 10.3389/fimmu.2022.1021703. eCollection 2022.
Neuromyelitis Optica (NMO) is an inflammatory demyelinating disease of the central nervous system (CNS). NMO manifests as selective and severe attacks on axons and myelin of the optic nerve and spinal cord, resulting in necrotic cavities. The circadian rhythms are well demonstrated to profoundly impact cellular function, behavior, and disease. This study is aimed to explore the role and molecular basis of circadian rhythms in NMO.
We used an Aquaporin 4(AQP4) IgG-induced NMO cell model in isolated astrocytes. The expression of Cx43 and Bmal1 were detected by real-time PCR and Western Blot. TAT-Gap19 and DQP-1105 were used to inhibit Cx43 and glutamate receptor respectively. The knockdown of Bmal1 were performed with the shRNA containing adenovirus. The levels of glutamate, anterior visual pathway (AVP), and vasoactive intestinal peptide (VIP) were quantified by ELISA kits.
We found that Bmal1 and Clock, two essential components of the circadian clock, were significantly decreased in NMO astrocytes, which were reversed by Cx43 activation (linoleic acid) or glutamate. Moreover, the expression levels of Bmal1 and Clock were also decreased by Cx43 blockade (TAT-Gap19) or glutamate receptor inhibition (DQP-1105). Furthermore, adenovirus-mediated Bmal1 knockdown by shRNA (Ad-sh-Bmal1) dramatically decreased the levels of glutamate, AVP, and VIP from neurons, and significantly down-regulated the protein level of Cx43 in NMO astrocytes with Cx43 activation (linoleic acid) or glutamate treatment. However, Bmal1 knockdown did not alter these levels in normal astrocytes with Cx43 blockade (TAT-Gap19) or glutamate receptor inhibition (DQP-1105).
Collectively, these results suggest that Cx43-glutamate signaling would be a critical upstream regulator that contributes to the NMO-induced rhythmic damage in SCN astrocytes.
视神经脊髓炎（NMO）是一种中枢神经系统（CNS）的炎症性脱髓鞘疾病。NMO 表现为视神经和脊髓轴突和髓鞘的选择性和严重攻击，导致坏死腔。昼夜节律被证明对细胞功能、行为和疾病有深远的影响。本研究旨在探讨昼夜节律在 NMO 中的作用和分子基础。
我们使用分离的星形胶质细胞中的水通道蛋白 4（AQP4）IgG 诱导的 NMO 细胞模型。通过实时 PCR 和 Western Blot 检测 Cx43 和 Bmal1 的表达。TAT-Gap19 和 DQP-1105 分别用于抑制 Cx43 和谷氨酸受体。用含有腺病毒的 shRNA 敲低 Bmal1。通过 ELISA 试剂盒定量谷氨酸、前视路（AVP）和血管活性肠肽（VIP）的水平。
我们发现，昼夜节律的两个重要组成部分 Bmal1 和 Clock 在 NMO 星形胶质细胞中显著降低，这一降低可被 Cx43 激活（亚油酸）或谷氨酸所逆转。此外，Cx43 阻断（TAT-Gap19）或谷氨酸受体抑制（DQP-1105）也降低了 Bmal1 和 Clock 的表达水平。此外，腺病毒介导的 shRNA（Ad-sh-Bmal1）敲低可显著降低神经元中的谷氨酸、AVP 和 VIP 水平，并显著下调 NMO 星形胶质细胞中 Cx43 的蛋白水平，而 Cx43 激活（亚油酸）或谷氨酸处理。然而，Bmal1 敲低并不改变 Cx43 阻断（TAT-Gap19）或谷氨酸受体抑制（DQP-1105）的正常星形胶质细胞中的这些水平。
总之，这些结果表明 Cx43-谷氨酸信号可能是一种关键的上游调节剂，有助于 SCN 星形胶质细胞中 NMO 诱导的节律性损伤。
