Department of Neurology, Faculty of Medicine and University Hospital of Cologne, University of Cologne, Cologne, Germany.
Department of Mechanobiology, Institute of Biological Information Processing (IBI-2), Research Centre Juelich, Juelich, Germany.
BMC Neurosci. 2024 Jun 26;25(1):29. doi: 10.1186/s12868-024-00876-x.
BACKGROUND: Astrocytes are the most abundant cell type of the central nervous system and are fundamentally involved in homeostasis, neuroprotection, and synaptic plasticity. This regulatory function of astrocytes on their neighboring cells in the healthy brain is subject of current research. In the ischemic brain we assume disease specific differences in astrocytic acting. The renin-angiotensin-aldosterone system regulates arterial blood pressure through endothelial cells and perivascular musculature. Moreover, astrocytes express angiotensin II type 1 and 2 receptors. However, their role in astrocytic function has not yet been fully elucidated. We hypothesized that the angiotensin II receptors impact astrocyte function as revealed in an in vitro system mimicking cerebral ischemia. Astrocytes derived from neonatal wistar rats were exposed to telmisartan (angiotensin II type 1 receptor-blocker) or PD123319 (angiotensin II type 2 receptor-blocker) under normal conditions (control) or deprivation from oxygen and glucose. Conditioned medium (CM) of astrocytes was harvested to elucidate astrocyte-mediated indirect effects on microglia and cortical neurons. RESULT: The blockade of angiotensin II type 1 receptor by telmisartan increased the survival of astrocytes during ischemic conditions in vitro without affecting their proliferation rate or disturbing their expression of S100A10, a marker of activation. The inhibition of the angiotensin II type 2 receptor pathway by PD123319 resulted in both increased expression of S100A10 and proliferation rate. The CM of telmisartan-treated astrocytes reduced the expression of pro-inflammatory mediators with simultaneous increase of anti-inflammatory markers in microglia. Increased neuronal activity was observed after treatment of neurons with CM of telmisartan- as well as PD123319-stimulated astrocytes. CONCLUSION: Data show that angiotensin II receptors have functional relevance for astrocytes that differs in healthy and ischemic conditions and effects surrounding microglia and neuronal activity via secretory signals. Above that, this work emphasizes the strong interference of the different cells in the CNS and that targeting astrocytes might serve as a therapeutic strategy to influence the acting of glia-neuronal network in de- and regenerative context.
背景:星形胶质细胞是中枢神经系统中最丰富的细胞类型,它们从根本上参与了体内平衡、神经保护和突触可塑性。星形胶质细胞对健康大脑中邻近细胞的这种调节功能是当前研究的主题。在缺血性大脑中,我们假设星形胶质细胞的作用存在疾病特异性差异。肾素-血管紧张素-醛固酮系统通过内皮细胞和血管周围的肌肉调节动脉血压。此外,星形胶质细胞表达血管紧张素 II 型 1 和 2 受体。然而,它们在星形胶质细胞功能中的作用尚未完全阐明。我们假设,血管紧张素 II 受体影响星形胶质细胞功能,正如在模拟脑缺血的体外系统中所揭示的那样。将来自新生 Wistar 大鼠的星形胶质细胞在正常条件(对照)或缺氧和葡萄糖剥夺下暴露于替米沙坦(血管紧张素 II 型 1 受体阻滞剂)或 PD123319(血管紧张素 II 型 2 受体阻滞剂)。收集星形胶质细胞的条件培养基(CM),以阐明星形胶质细胞对小胶质细胞和皮质神经元的间接作用。 结果:替米沙坦阻断血管紧张素 II 型 1 受体可增加体外缺血条件下星形胶质细胞的存活率,而不影响其增殖率或干扰其 S100A10 的表达,S100A10 是激活的标志物。PD123319 抑制血管紧张素 II 型 2 受体途径可导致 S100A10 表达增加和增殖率增加。替米沙坦处理的星形胶质细胞的 CM 可降低小胶质细胞中促炎介质的表达,同时增加抗炎标志物的表达。用替米沙坦和 PD123319 刺激的星形胶质细胞的 CM 处理神经元后,神经元的活性增加。 结论:数据表明,血管紧张素 II 受体对星形胶质细胞具有功能相关性,在健康和缺血条件下,以及通过分泌信号影响小胶质细胞和神经元活性方面,其作用不同。此外,这项工作强调了中枢神经系统中不同细胞的强烈干扰,靶向星形胶质细胞可能是一种治疗策略,以影响去再生和再生背景下的神经胶质-神经元网络的作用。
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