Regulatory mechanisms and therapeutic strategies for cellular autophagy after spinal cord injury
BACKGROUND:Cellular autophagy maintains metabolism and in vivo homeostasis through the autophagosome-lysosome degradation pathway,which is closely related to the impaired cell death and functional recovery of distal neurons after spinal cord injury,and targeting cellular autophagy to promote the functional recovery of the spinal cord after spinal cord injury is a promising therapeutic direction.OBJECTIVE:To summarize the role of cellular autophagy in spinal cord injury,related regulatory mechanisms of cellular autophagy and therapeutic strategies.METHODS:PubMed and CNKI databases were searched with the search terms of"spinal cord injury,autophagy,regulatory mechanisms,autophagy pathway,therapeutic target"in English and Chinese,respectively.A total of 133 English and 4 Chinese articles were included for review.RESULTS AND CONCLUSION:(1)Autophagy,a form of programmed cell death,has been shown to play a crucial role in the progression and treatment of spinal cord injury.Most studies have shown that moderate activation or promotion of autophagy promotes neurological recovery by decreasing inflammatory responses and apoptosis.A few studies have reported that excessive activation of autophagy,on the contrary,impedes neurological recovery following spinal cord injury.(2)After spinal cord injury,PI3K/AKT/mTOR,MAPK,AMPK and p53 signaling pathways,and factors such as Beclin-1,ATG and LC3 regulate the initiation and development of cell autophagy in a positive or negative manner.(3)Promoting or inhibiting autophagy may be a promising therapeutic strategy to modulate the pathogenesis of traumatic spinal cord injury.And the drugs amlodipine,metformin,and minocycline,the Chinese medicines hawthorn leaf total flavonoids,betulinic acid,oxidized ginseng saponins,acupuncture,and extracellular vesicles of different cellular origins,exosomes and reactive oxygen species-responsive composite fibers as activators of cellular autophagy attenuate secondary injury in response to spinal cord injury by activating cellular autophagy,while the drugs insulin-like growth factor 1 and eladavone,Chinese medicine ginseng saponin,acupuncture,and hydrogel carrying basic fibroblast growth factor as inhibitors of cellular autophagy promote functional recovery after spinal cord injury by inhibiting excessive cellular autophagy.(4)The related regulators of cellular autophagy are interconnected,and the bi-directional effects of cellular autophagy on spinal cord injury make it necessary to further explore the dominant factors that regulate cellular autophagy.(5)Research on the use of autophagy as a therapeutic target for spinal cord injury is mostly carried out in animal models,but there are no autophagy-related drugs used in the clinical practice,and their safety and efficacy need to be further investigated in the clinical field.