Goldshmit Yona, Kanner Sivan, Zacs Maria, Frisca Frisca, Pinto Alexander R, Currie Peter D, Pinkas-Kramarski Ronit
Department of Neurobiology, Tel-Aviv University, Israel; Australian Regenerative Medicine Institute, Monash University, VIC, Australia.
Department of Neurobiology, Tel-Aviv University, Israel.
Mol Cell Neurosci. 2015 Sep;68:82-91. doi: 10.1016/j.mcn.2015.04.006. Epub 2015 Apr 30.
Spinal cord injury (SCI) frequently leads to a permanent functional impairment as a result of the initial injury followed by secondary injury mechanism, which is characterised by increased inflammation, glial scarring and neuronal cell death. Finding drugs that may reduce inflammatory cell invasion and activation to reduce glial scarring and increase neuronal survival is of major importance for improving the outcome after SCI. In the present study, we examined the effect of rapamycin, an mTORC1 inhibitor and an inducer of autophagy, on recovery from spinal cord injury. Autophagy, a process that facilitates the degradation of cytoplasmic proteins, is also important for maintenance of neuronal homeostasis and plays a major role in neurodegeneration after neurotrauma. We examined rapamycin effects on the inflammatory response, glial scar formation, neuronal survival and regeneration in vivo using spinal cord hemisection model in mice, and in vitro using primary cortical neurons and human astrocytes. We show that a single injection of rapamycin, inhibited p62/SQSTM1, a marker of autophagy, inhibited mTORC1 downstream effector p70S6K, reduced macrophage/neutrophil infiltration into the lesion site, microglia activation and secretion of TNFα. Rapamycin inhibited astrocyte proliferation and reduced the number of GFAP expressing cells at the lesion site. Finally, it increased neuronal survival and axonogenesis towards the lesion site. Our study shows that rapamycin treatment increased significantly p-Akt levels at the lesion site following SCI. Similarly, rapamycin treatment of neurons and astrocytes induced p-Akt elevation under stress conditions. Together, these findings indicate that rapamycin is a promising candidate for treatment of acute SCI condition and may be a useful therapeutic agent.
脊髓损伤（SCI）常因初始损伤后继发的损伤机制而导致永久性功能障碍，其特征为炎症增加、胶质瘢痕形成和神经元细胞死亡。寻找能够减少炎性细胞浸润和活化以减轻胶质瘢痕形成并增加神经元存活的药物，对于改善脊髓损伤后的预后至关重要。在本研究中，我们检测了雷帕霉素（一种mTORC1抑制剂和自噬诱导剂）对脊髓损伤恢复的影响。自噬是一个促进细胞质蛋白降解的过程，对于维持神经元内环境稳定也很重要，并且在神经创伤后的神经退行性变中起主要作用。我们使用小鼠脊髓半切模型在体内检测了雷帕霉素对炎症反应、胶质瘢痕形成、神经元存活和再生的影响，并在体外使用原代皮质神经元和人星形胶质细胞进行了检测。我们发现，单次注射雷帕霉素可抑制自噬标志物p62/SQSTM1，抑制mTORC1下游效应物p70S6K，减少巨噬细胞/中性粒细胞浸润到损伤部位，抑制小胶质细胞活化及肿瘤坏死因子α（TNFα）的分泌。雷帕霉素抑制星形胶质细胞增殖，并减少损伤部位表达胶质纤维酸性蛋白（GFAP）的细胞数量。最后，它增加了神经元存活并促进轴突向损伤部位生长。我们的研究表明，脊髓损伤后雷帕霉素治疗可显著提高损伤部位的磷酸化Akt（p-Akt）水平。同样，在应激条件下，雷帕霉素处理神经元和星形胶质细胞可诱导p-Akt升高。总之，这些发现表明雷帕霉素是治疗急性脊髓损伤的一个有前景的候选药物，可能是一种有用的治疗剂。
