Kaya Zeynep, Belder Nevin, Sever-Bahçekapılı Melike, Erdener Şefik Evren, Dönmez-Demir Buket, Bağcı Canan, Köroğlu Merve Nur, Bilguvar Kaya, Dalkara Turgay
Institute of Neurological Sciences and Psychiatry, Hacettepe University, 06100, Ankara, Turkey.
Department of Biostatistics and Bioinformatics, Institute of Health Sciences, Acıbadem Mehmet Ali Aydınlar University, 34684, Istanbul, Turkey.
Brain. 2025 Jan 17. doi: 10.1093/brain/awaf015.
Cortical spreading depolarization (CSD), the neurophysiological event believed to underlie aura, may trigger migraine headaches through inflammatory signaling that originates in neurons and spreads to the meninges via astrocytes. Increasing evidence from studies on rodents and migraine patients supports this hypothesis. The transition from pro-inflammatory to anti-inflammatory mechanisms is crucial for resolving inflammation. However, the resolution of inflammation in the context of CSD and migraine headaches remains poorly understood. This study aims to elucidate the progression of post-CSD inflammatory signaling and its resolution in neurons, astrocytes, and microglia in mouse brains. CSD was triggered optogenetically or by pinprick. HMGB1 release, caspase-1 activation, and cell-specific activation of NF-κB pairs, along with ensuing transcriptomic changes, were evaluated using immunofluorescence, Western blotting, co-immunoprecipitation, FRET analysis, and cell-specific transcriptomics. Our findings indicate that after the initial burst, HMGB1 release from neurons ceased, and caspase-1 activation, which peaked 1-hour post-CSD, diminished within 3-5 hours. This suggests that pro-inflammatory stimuli driving inflammatory signaling decreased within hours after CSD. Pro-inflammatory NF-κB p65:p50 pairs, along with anti-inflammatory cRel:p65 pairs, were detected in astrocyte nuclei shortly after CSD. However, 24 hours post-CSD, the former had disappeared while the latter persisted, indicating a shift from pro-inflammatory to anti-inflammatory activity in astrocytes. Pathway analysis of cell-specific transcriptomic data confirmed NF-κB-related pro-inflammatory transcription in astrocytes 1-hour post-CSD, while no such activity was observed in neurons. Detailed transcriptomic analysis with Bayesian cell proportion reconstruction revealed that microglia exhibited transcriptional changes trending towards an anti-inflammatory profile, along with upregulation of several chemokines and cytokines (e.g., TNF). This suggests that microglia may play a role in supporting the inflammatory responses in astrocytes through the release of these mediators. The upregulation of genes involved in chemotaxis (e.g., Ccl3) and spine pruning (e.g., C1q) in microglia implies that microglia may contribute to synaptic repair, while inflammatory signaling in astrocytes could potentially modulate meningeal nociceptor activity through an extensive astrocyte endfeet syncytium abutting subarachnoid and perivascular spaces although direct evidence remains incomplete. This nuanced understanding of the inflammatory response in CNS cell types highlights the intricate cellular interactions and responses to CSD. Following a single CSD, distinct transcriptomic responses occur in neurons, astrocytes, and microglia, driving inflammatory and anti-inflammatory responses, potentially contributing to headache initiation and resolution.
皮层扩散性去极化(CSD)是一种被认为是先兆基础的神经生理事件,它可能通过炎症信号触发偏头痛,这种炎症信号起源于神经元,并通过星形胶质细胞扩散到脑膜。来自啮齿动物和偏头痛患者研究的越来越多的证据支持这一假说。从促炎机制向抗炎机制的转变对于解决炎症至关重要。然而,在CSD和偏头痛背景下炎症的消退仍知之甚少。本研究旨在阐明小鼠大脑中CSD后炎症信号的进展及其在神经元、星形胶质细胞和小胶质细胞中的消退情况。通过光遗传学或针刺触发CSD。使用免疫荧光、蛋白质免疫印迹、免疫共沉淀、荧光共振能量转移分析和细胞特异性转录组学评估高迁移率族蛋白B1(HMGB1)释放、半胱天冬酶-1激活以及NF-κB对的细胞特异性激活,以及随后的转录组变化。我们的研究结果表明,在最初的爆发后,神经元释放的HMGB1停止,半胱天冬酶-1激活在CSD后1小时达到峰值,并在3至5小时内减弱。这表明驱动炎症信号的促炎刺激在CSD后数小时内减少。CSD后不久,在星形胶质细胞核中检测到促炎NF-κB p65:p50对以及抗炎cRel:p65对。然而,CSD后24小时,前者消失而后者持续存在,表明星形胶质细胞中从促炎活性向抗炎活性的转变。对细胞特异性转录组数据的通路分析证实,CSD后1小时星形胶质细胞中有与NF-κB相关的促炎转录,而在神经元中未观察到这种活性。使用贝叶斯细胞比例重建的详细转录组分析表明,小胶质细胞表现出趋向抗炎特征的转录变化,同时几种趋化因子和细胞因子(如肿瘤坏死因子)上调。这表明小胶质细胞可能通过释放这些介质在支持星形胶质细胞的炎症反应中发挥作用。小胶质细胞中参与趋化作用(如Ccl3)和棘突修剪(如C1q)的基因上调意味着小胶质细胞可能有助于突触修复,而星形胶质细胞中的炎症信号可能通过广泛的星形胶质细胞终足合胞体邻接蛛网膜下腔和血管周围空间潜在地调节脑膜伤害感受器活动,尽管直接证据仍然不完整。对中枢神经系统细胞类型中炎症反应的这种细致入微的理解突出了细胞间复杂的相互作用以及对CSD的反应。在单次CSD后,神经元、星形胶质细胞和小胶质细胞中会发生不同的转录组反应,驱动炎症和抗炎反应,可能有助于头痛的发作和缓解。
Annu Rev Neurosci. 2023-7-10