Shih Hsin-Ling, Cheng Kuan-Hsiang, Chen Chin-Hao, Chang Jang-Yang, Hsu Kuei-Sen
Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
J Neurochem. 2025 Mar;169(3):e70037. doi: 10.1111/jnc.70037.
Status epilepticus (SE) is a life-threatening neurological emergency characterized by persistent seizures, leading to brain damage that increases the risk of recurrent seizures due to abnormal electrical impulses produced by damaged neurons. However, the molecular mechanism by which convulsive SE leads to neuronal damage is not completely understood. Cathepsin S (Ctss), a lysosomal cysteine protease, has been implicated in secondary injury after traumatic brain injury. This study sought to explore whether Ctss is also involved in SE-induced neuronal damage in the hippocampus. Immunohistochemistry and Western blotting were utilized to detect the expression of Ctss in the hippocampal subregions of male C57BL/6J mice at various times following kainic acid (KA)-induced SE. The reactivity of microglia was assessed using immunohistochemistry, and Fluoro-Jade C (FJC) staining was employed to identify damaged neurons. We found that the mature form of Ctss is barely observed in naïve adult (12-week-old) mouse hippocampus, but its expression is significantly evident at 50 weeks of age. In adult mice, the expression of both pro-and mature forms of Ctss in the hippocampal CA3 region was increased as early as 16 h following KA-induced SE. The increased Ctss immunoreactivity was mainly found in microglia following KA-induced SE. The damaged neurons visualized by FJC staining were prominent in the CA3 region at 16 h following KA-induced SE. Ctss knockdown did not affect KA-induced behavioral seizures but significantly reduced SE-induced microglia activation and neuronal damage. An increase in chemokine CX3C motif ligand 1 (CX3CL1) immunoreactivity on microglia was observed following KA-induced SE, and CX3C motif chemokine receptor 1 (CX3CR1) antagonist AZD8797 treatment significantly attenuated SE-induced microglia activation and neuronal damage. Altogether, these results indicate a crucial role of Ctss in SE-induced neuronal damage, possibly through CXC3L1-mediated microglial activation, and provide a new perspective for preventing SE-induced neuronal damage.
癫痫持续状态（SE）是一种危及生命的神经急症，其特征为持续性癫痫发作，会导致脑损伤，因受损神经元产生的异常电冲动而增加癫痫复发风险。然而，惊厥性SE导致神经元损伤的分子机制尚未完全明确。组织蛋白酶S（Ctss）是一种溶酶体半胱氨酸蛋白酶，已被证实与创伤性脑损伤后的继发性损伤有关。本研究旨在探讨Ctss是否也参与SE诱导的海马神经元损伤。利用免疫组织化学和蛋白质免疫印迹法检测了在 kainic 酸（KA）诱导的SE后不同时间点雄性C57BL/6J小鼠海马亚区中Ctss的表达。使用免疫组织化学评估小胶质细胞的反应性，并采用 Fluoro-Jade C（FJC）染色来识别受损神经元。我们发现，在未成熟的成年（12周龄）小鼠海马中几乎观察不到成熟形式的Ctss，但其表达在50周龄时显著明显。在成年小鼠中，KA诱导的SE后最早在16小时，海马CA3区中Ctss的前体和成熟形式的表达均增加。KA诱导的SE后，Ctss免疫反应性增加主要见于小胶质细胞。FJC染色显示的受损神经元在KA诱导的SE后16小时在CA3区很突出。Ctss基因敲低不影响KA诱导的行为性癫痫发作，但显著减少SE诱导的小胶质细胞活化和神经元损伤。KA诱导的SE后观察到小胶质细胞上趋化因子CX3C基序配体1（CX3CL1）免疫反应性增加，CX3C基序趋化因子受体1（CX3CR1）拮抗剂AZD8797治疗显著减轻SE诱导的小胶质细胞活化和神经元损伤。总之，这些结果表明Ctss在SE诱导的神经元损伤中起关键作用，可能通过CXC3L1介导的小胶质细胞活化，为预防SE诱导的神经元损伤提供了新的视角。
