Deletion of Bak1 alleviates microglial necroptosis and neuroinflammation after experimental subarachnoid hemorrhage

• Published in: Journal of neurochemistry 2023-03, Vol.164 (6), p.829-846
• Main Authors: Qiu, Xiancheng, Tao, Qianke, Zhang, Lihan, Kuang, Chenghao, Xie, Yuke, Zhang, Lifang, Yin, Shigang, Peng, Jianhua, Jiang, Yong
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis; Bak1; bcl-2 Homologous Antagonist-Killer Protein - genetics; bcl-2 Homologous Antagonist-Killer Protein - metabolism; Cell injury; Central nervous system; Gene expression; Hemorrhage; In vivo methods and tests; Inflammation; Kinases; MAP kinase; Mice; Microglia; Microglia - metabolism; Mitochondria; Necroptosis; Neurodegenerative diseases; neuroinflammation; Neuroinflammatory Diseases; Oxidative stress; Oxyhemoglobin; Permeability; Phenotypes; Proteins; Subarachnoid hemorrhage; Subarachnoid Hemorrhage - metabolism; Thrombospondin; thrombospondin 1; Transcription Factors - metabolism; Viruses
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/jnc.15751

Microglial necroptosis exacerbates neurodegenerative diseases, central nervous system (CNS) injury, and demonstrates a proinflammatory process, but its contribution to subarachnoid hemorrhage (SAH) is poorly characterized. BCL‐2 homologous antagonist‐killer protein (Bak1), a critical regulatory molecule of endogenous apoptosis, can be involved in the pathologic process of necroptosis by regulating mitochondrial permeability. In this study, we revealed microglia undergo necroptosis after SAH in vivo and vitro. Western blot revealed that Bak1 was elevated at 24 h after SAH. Knocked down of Bak1 by adeno‐associated virus attenuates microglial necroptosis, alleviates neuroinflammation, and improves neurologic function after SAH in mice. Furthermore, oxyhemoglobin (10 μM) induced necroptosis in BV2 microglia, increasing Bak1 expression and mediating proinflammatory phenotype transformation, exacerbating oxidative stress and neuroinflammation. Abrogating BV2 Bak1 could reduce necroptosis by down‐regulating the expression of phosphorylated pseudokinase mixed lineage kinase domain‐like protein (p‐MLKL), then down‐regulating proinflammatory phenotype gene expression. RNA‐Seq showed that disrupting BV2 Bak1 down‐regulates multiple immune and inflammatory pathways and ameliorates cell injury by elevating thrombospondin 1 (THBS1) expression. In summary, we identified a critical regulatory role for Bak1 in microglial necroptosis and neuroinflammation after SAH. Bak1 is expected to be a potential target for the treatment strategy of SAH. Subarachnoid hemorrhage induces necroptosis of microglia. Deletion of Bak1 protein exerts a protective effect on microglia by reducing p‐MLKL content and up‐regulating THBS1 protein expression, while reducing microglia‐mediated neuroinflammation.