小胶质细胞活化促进syncytin-1介导的脊髓运动神经元损伤的机制

We first reported the abnormal expression of human endogenous retrovirus ERVWE1 env gene encoding protein syncytin-1 in the atrophied skeletal muscles of motor neuron disease. The abnormal high expression of syncytin-1 in the skeletal muscles of mice led to the microglia activation, degeneration of motor neurons of spinal lumbar enlargement, and neurogenic damage of skeletal muscles. However, the roles and mechanisms of microglia activation in the induction of motor neuron injury by abnormal expression of syncytin-1 are not clear. By using anterior tibial muscle implantation of syncytin-1 expression vector in mice, the proinflammatory/anti-inflammatory type (M1/M2) activation of microglial cells as well as the injury of motor neurons in the spinal lumbar enlargement would be detected. By using the co-culture system of microglia and motor neurons, the mechanisms of motor neuron injury induced by syncytin-1, which include the inflammatory cascade reaction, the generation of reactive oxygen species, and oxidative stress, would be explored. By using the Rho kinase inhibitor to mediate the imbalance of M1/M2 type induced by syncytin-1, we further explore the effects of Rho kinase inhibitor in protecting the motor neurons from the damage caused by abnormal transcription of syncytin-1. The Inflammatory regulation and immuno toxicity of syncytin-1 in activating microglial pathway would be clarified.

我们在国际上首次报道了编码蛋白syncytin-1的人内源性逆转录病毒ERVWE1 env基因在运动神经元病萎缩骨骼肌异常表达；小鼠骨骼肌syncytin-1异常高表达激活小胶质细胞，导致腰段脊髓运动神经元变性，骨骼肌呈神经源性损伤。小胶质细胞活化在syncytin-1异常表达诱导运动神经元损伤中的作用和机制不清。本课题应用胫前肌植入syncytin-1表达载体小鼠模型，检测腰段脊髓促炎症/抗炎症型（M1/M2型）小胶质细胞的活化和神经元损伤；应用小胶质细胞、运动神经元共培养体系，从炎症级联反应和氧化应激损伤等方面探讨小胶质细胞活化促进syncytin-1诱导的运动神经元损伤的机制；采用Rho激酶抑制剂调节syncytin-1诱导的M1/M2型小胶质细胞失平衡，探讨其对syncytin-1诱导的运动神经元损伤的保护作用，阐明syncytin-1激活小胶质细胞通路的炎症调节作用和免疫毒性。

我们在国际上首次报道了编码蛋白syncytin-1的人内源性逆转录病毒ERVWE1 env基因在运动神经元病萎缩骨骼肌异常表达；小鼠骨骼肌syncytin-1异常高表达激活小胶质细胞，导致腰段脊髓运动神经元变性，骨骼肌呈神经源性损伤。小胶质细胞活化在syncytin-1异常表达诱导运动神经元损伤中的作用和机制不清。本项目采用胫前肌骨骼肌高表达syncytin-1诱导脊髓小胶质细胞的活化，结果显示骨骼肌高表达syncytin-1引起腰段脊髓M1/M2型小胶质细胞失平衡，促炎症M1型小胶质细胞增多，抗炎症M2型小胶质细胞减少，M1型小胶质细胞分泌的炎症因子iNOS增多，提示骨骼肌高表达syncytin-1使得腰段脊髓的促炎症M1型小胶质细胞的活化，炎症因子释放增多，炎症损伤引起运动神经元损伤，导致运动功能损害。采用Rho激酶抑制剂法舒地尔干预，可调节syncytin-1诱导的M1/M2型小胶质细胞失平衡，促使小胶质细胞从促炎症M1型向抗炎症M2型转变，从而对syncytin-1诱导的运动神经元损伤起保护作用。应用原代小胶质细胞、运动神经元细胞共培养体系，转染syncytin表达载体，结果显示促炎症细胞因子IL-6、TNF-α增加, 抗炎症细胞因子IL-10的水平降低，提示炎症损伤促进syncytin-1诱导的运动神经元损伤；Rho激酶抑制剂盐酸法舒地尔预处理可调节高表达syncytin-1引起的M1/M2型小胶质细胞失平衡，促炎症细胞因子IL-6、TNF-α减少, 抗炎症细胞因子IL-10的水平增加，从而保护神经元。本研究阐明了syncytin-1 通过激活小胶质细胞损伤运动神经元的炎症调节作用，Rho激酶抑制剂盐酸法舒地尔可调节高表达syncytin-1引起的M1/M2型小胶质细胞失平衡，减轻炎症损害，保护神经功能，这可能提供研究 MND 发病机制的新靶向和 MND 神经免疫通路靶向治疗的新策略。