Li Hui, Wang Pengfei, Tang Lin, Sun Jingjing, Zhang Yanling, Luo Wei, Luo Cong, Hu Zhaolan, Yang Lin
Department of Anesthesiology, The Second Xiangya Hospital, Central South University, Changsha, People's Republic of China.
Hunan Province Center for Clinical Anesthesia and Anesthesiology, Research Institute of Central South University, Changsha, People's Republic of China.
J Inflamm Res. 2021 Oct 13;14:5227-5239. doi: 10.2147/JIR.S335382. eCollection 2021.
Recent studies indicate that microglia and monocyte-derived macrophages (MDMs) have different roles in diseases such as stroke and spinal cord injury, yet their respective polarized phenotypes and roles remain unclear in spinal cord ischemia/reperfusion injury (SCIRI).
We established a mouse model of SCIRI by transient aortic occlusion followed by reperfusion. Basso mouse scale (BMS) scores were used to test the locomotor functions. The histopathological changes in spinal cord were assessed by hematoxylin-eosin staining and NF-200 immunohistochemistry. Real-time PCR, immunofluorescence and flow cytometry were employed to analyze the polarized phenotypes of the microglia and infiltrating MDMs, and the resulting inflammatory responses. Furthermore, the role of infiltrating MDMs were investigated by MDMs depletion using systemic administration of clodronate-liposomes.
SCIRI significantly impaired locomotor function of mice, accompanied with progressed necrosis, infiltration of inflammatory cells and neuron loss in the spinal cord. M1-related pro-inflammatory markers (iNOS, CD16, CD86 and TNF-α) increased dramatically in the early phase following SCIRI. In contrast, M2-related anti-inflammatory markers (CD204 and CD206) elevated at later stage. Besides, the invading MDMs were principally pro-inflammatory M1 type, transiently restricted to the first week after SCIRI. In contrast, microglia were the main source of anti-inflammatory M2 type. Furthermore, depletion of MDMs by clodronate-liposomes significantly preserved neurological functions and relieved neuronal damage caused by SCIRI.
These findings suggested distinct polarized status of resident microglia and MDMs following SCIRI. Inhibition of the invading MDMs may represent a novel approach for SCIRI treatment.
近期研究表明，小胶质细胞和单核细胞衍生的巨噬细胞（MDMs）在中风和脊髓损伤等疾病中发挥着不同作用，但它们各自的极化表型和作用在脊髓缺血/再灌注损伤（SCIRI）中仍不明确。
我们通过短暂性主动脉阻断随后再灌注建立了SCIRI小鼠模型。使用Basso小鼠评分（BMS）来测试运动功能。通过苏木精-伊红染色和NF-200免疫组织化学评估脊髓的组织病理学变化。采用实时PCR、免疫荧光和流式细胞术分析小胶质细胞和浸润性MDMs的极化表型以及由此产生的炎症反应。此外，通过全身给予氯膦酸盐脂质体耗尽MDMs来研究浸润性MDMs的作用。
SCIRI显著损害小鼠的运动功能，同时伴有脊髓坏死进展、炎症细胞浸润和神经元丢失。M1相关的促炎标志物（诱导型一氧化氮合酶、CD16、CD86和肿瘤坏死因子-α）在SCIRI后的早期显著增加。相比之下，M2相关的抗炎标志物（CD204和CD206）在后期升高。此外，侵入的MDMs主要是促炎M1型，在SCIRI后的第一周短暂受限。相比之下，小胶质细胞是抗炎M2型的主要来源。此外，氯膦酸盐脂质体耗尽MDMs可显著保留神经功能并减轻SCIRI引起的神经元损伤。
这些发现表明SCIRI后常驻小胶质细胞和MDMs存在不同的极化状态。抑制侵入的MDMs可能代表一种治疗SCIRI的新方法。
