Prolonged astrocyte-derived erythropoietin expression attenuates neuronal damage under hypothermic conditions
Prolonged astrocyte-derived erythropoietin expression attenuates neuronal damage under hypothermic conditions
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DOI：
10.1186/s12974-020-01831-3
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发表时间：
2020-05-02
影响因子：
9.3
通讯作者：
Aoyama, Mineyoshi
中科院分区：
文献类型：
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作者：
Toriuchi, Kohki;Kakita, Hiroki;Aoyama, Mineyoshi
研究背景缺氧缺血性脑病（HIE）是一种发病率高、伴有严重神经功能缺损（包括脑瘫）的疾病。治疗性低温（TH）已被证明可以降低新生儿缺氧缺血性脑病的死亡率，并提供神经保护。然而，TH治疗的HIE婴儿的死亡率和残疾率仍然很高。虽然TH的神经保护作用的细胞机制尚不清楚，但已知星形细胞促红细胞生成素（EPO）是缺氧条件下神经保护的关键介质。在本研究中，我们研究了低温对星形胶质细胞中EPO表达的影响，并确定低温是否通过EPO信号转导减轻神经元损伤。方法在缺氧缺糖（OGD）条件下培养大鼠大脑皮层星形胶质细胞。评估EPO和EPO转录因子缺氧诱导因子（HIF）的表达。在OGD后，在常温（37 ° C）或低温（33.5 ° C）条件下培养星形胶质细胞，然后评估EPO和HIF表达。OGD后，大鼠皮层神经元培养在星形胶质细胞条件培养基（ACM）从低温组，和神经细胞凋亡进行了评价。结果OGD诱导EPO mRNA和蛋白表达，但水平低于单纯缺氧。缺氧和OGD条件下，HIF-1 α和HIF-2 α蛋白表达增加，但OGD增加HIF-2 α蛋白表达的程度低于缺氧。OGD后EPO基因和蛋白表达在低温下显著升高。此外，在低温下，HIF-1 α和HIF-2 α蛋白的表达增强。在ACM的存在下，来自低温星形胶质细胞OGD后，裂解的caspase 3和TdT介导的dUTP缺口末端标记阳性凋亡神经元的数量低于ACM的存在下，从常温星形胶质细胞OGD后。使用抗EPO中和抗体阻断EPO信号转导减弱了OGD后低温星形胶质细胞来源的ACM的抗凋亡作用。结论缺氧缺糖后低温可稳定星形胶质细胞HIF-EPO信号通路，并上调EPO表达，抑制神经细胞凋亡。研究低温条件下星形胶质细胞中EPO的神经保护作用可能有助于开发新的神经保护治疗HIE的方法。
Background Hypoxic-ischemic encephalopathy (HIE) has a high morbidity rate and involves severe neurologic deficits, including cerebral palsy. Therapeutic hypothermia (TH) has been shown to decrease the mortality rate and provide neuroprotection in infants with HIE. However, death and disability rates in HIE infants treated with TH remain high. Although the cellular mechanism of the neuroprotective effect of TH remains unclear, astrocytic erythropoietin (EPO) is known to be a key mediator of neuroprotection under hypoxic conditions. In the present study, we investigated the hypothermia effect on EPO expression in astrocytes and determined whether hypothermia attenuates neuronal damage via EPO signaling. Methods Astrocytes derived from rat cerebral cortex were cultured under oxygen/glucose deprivation (OGD). The expression of EPO and hypoxia-inducible factor (HIF), a transcription factor of EPO, was assessed. After OGD, astrocytes were cultured under normothermic (37 degrees C) or hypothermic (33.5 degrees C) conditions, and then EPO and HIF expression was assessed. After OGD, rat cortical neurons were cultured in astrocyte-conditioned medium (ACM) derived from the hypothermic group, and neuronal apoptosis was evaluated. Results OGD induced EPO mRNA and protein expression, although at lower levels than hypoxia alone. HIF-1 alpha and HIF-2 alpha protein expression increased under hypoxia alone and OGD, although OGD increased HIF-2 alpha protein expression less than hypoxia alone. EPO gene and protein expression after OGD was significantly higher under hypothermia. Moreover, expression of HIF-1 alpha and HIF-2 alpha protein was enhanced under hypothermia. In the presence of ACM derived from hypothermic astrocytes following OGD, the number of cleaved caspase 3 and TdT-mediated dUTP nick-end labeling-positive apoptotic neurons was lower than in the presence of ACM from normothermic astrocytes following OGD. Blockade of EPO signaling using anti-EPO neutralization antibody attenuated the anti-apoptotic effect of ACM derived from hypothermic astrocytes following OGD. Conclusions Hypothermia after OGD stabilized HIF-EPO signaling in astrocytes, and upregulated EPO expression could suppress neuronal apoptosis. Investigating the neuroprotective effect of EPO from astrocytes under hypothermic conditions may contribute to the development of novel neuroprotection-based therapies for HIE.