Department of Forensic Pathology, China Medical University School of Forensic Medicine, Shenyang, China.
Department of Histology and Embryology, College of Basic Medical Sciences, China Medical University, Shenyang, China.
Eur J Neurosci. 2019 Jul;50(2):1981-1993. doi: 10.1111/ejn.14399. Epub 2019 Apr 23.
Nrf2 plays a pivotal role in antioxidant response and anti-inflammation after traumatic brain injury (TBI), and its deletion aggravates TBI-induced brain damage. Previous studies have demonstrated that Nrf2 is activated post TBI, but dynamic changes in expression and cell type-specific characteristics remain unclear. In this study, the Feeney weight-drop contusion model was conducted to mimic TBI, and the ipsilateral cerebral cortex was collected at 1, 3, 7 and 14 days post TBI (dpi). Nrf2 protein levels were observed by western blot. Cell type-specific localization of Nrf2 after TBI was detected at different time intervals by double immunofluorescence staining. NeuN, GFAP, IBA1 and NG2 were used as cell type-specific markers to neurons, astrocytes, microglia and NG2 glia, respectively. After TBI, Nrf2 protein levels peaked at 1 dpi. Robust transient Nrf2 accumulation was co-localized with neurons, which was predominant at 1 dpi. Continuous weak Nrf2 expression was detected in activated astrocytes, and the number of double positive cells peaked at 7 dpi. Inducible widespread immunostaining of Nrf2 was observed in the nucleus of the microglia, and the number of Nrf2+ microglia peaked at 7 dpi. In addition, we also explored colocalization of Nrf2 in NG2 glia, in which the percentage of Nrf2+ in NG2 glia reached a climax at 3 dpi. This study reveals that the accumulation of endogenous Nrf2 might mediate different pathophysical roles in neurons and glias after TBI, the cell-type specific and time-dependent expression provide insights to explain the roles of Nrf2 in different neural cells.
Nrf2 在创伤性脑损伤（TBI）后的抗氧化反应和抗炎中发挥关键作用，其缺失会加重 TBI 引起的脑损伤。先前的研究表明，Nrf2 在 TBI 后被激活，但表达的动态变化和细胞类型特异性特征仍不清楚。在这项研究中，使用 Feeney 重物坠落挫伤模型模拟 TBI，并在 TBI 后 1、3、7 和 14 天（dpi）采集对侧大脑皮质。通过 Western blot 观察 Nrf2 蛋白水平。通过双重免疫荧光染色在不同时间间隔检测 TBI 后 Nrf2 的细胞类型特异性定位。NeuN、GFAP、IBA1 和 NG2 分别作为神经元、星形胶质细胞、小胶质细胞和 NG2 胶质细胞的细胞类型特异性标志物。TBI 后，Nrf2 蛋白水平在 1 dpi 时达到峰值。强烈的瞬时 Nrf2 积累与神经元共定位，在 1 dpi 时占主导地位。在活化的星形胶质细胞中检测到持续的弱 Nrf2 表达，双阳性细胞的数量在 7 dpi 时达到峰值。小胶质细胞核中观察到诱导性广泛的 Nrf2 免疫染色，Nrf2+小胶质细胞的数量在 7 dpi 时达到峰值。此外，我们还探讨了 Nrf2 在 NG2 胶质细胞中的共定位，其中 Nrf2+在 NG2 胶质细胞中的百分比在 3 dpi 时达到高峰。本研究揭示了内源性 Nrf2 的积累可能在 TBI 后神经元和神经胶质细胞中介导不同的病理生理作用，细胞类型特异性和时间依赖性表达为解释 Nrf2 在不同神经细胞中的作用提供了线索。
