2023, Vol. 27 ›› Issue (1): 121-129

Effect of inflammatory reaction mediated by microglia polarization in spinal cord injury

Shi Xu1, Li Ruiyu1, Zhang Bing1, Chen Qi2, Zuo Hua2   

Abstract: BACKGROUND: Microglia polarization participates in and plays a key role in the inflammatory response after spinal cord injury. Related studies have shown that effectively inducing the polarization of microglia from M1 pro-inflammatory phenotype to M2 anti-inflammatory phenotype can reduce the inflammatory response after spinal cord injury and promote tissue repair and regeneration and the recovery of nerve function.  
OBJECTIVE: To review the inflammatory response after spinal cord injury, function and polarization of microglia and the effect of microglia polarization on spinal cord injury and its potential regulation strategies.
METHODS: Databases of PubMed, Web of Science, and CNKI were searched for the articles with the keywords of “microglia, polarization, spinal cord injury, inflammation” in English and Chinese respectively. Finally, a total of 80 articles were included according to the inclusion and exclusion criteria.  
RESULTS AND CONCLUSION: (1) Stable and persistent inflammatory response mediated by microglia is very important for the prognosis of spinal cord injury. (2) Under physiological conditions, microglia are in the resting phenotype of M0. After spinal cord injury, microglia are activated and then polarized into M1 pro-inflammatory phenotype, resulting in decreased tissue repair ability and persistent neuroinflammation. (3) During inflammation, regulating the polarization of microglia to M2 phenotype or at least tilting to M2 is beneficial to inhibit oxidative stress, regulate synaptic remodeling, and promote axonal regeneration and angiogenesis. It is an effective control strategy. (4) At present, the main strategies to regulate the phenotypic transition of microglia between M1 and M2 are mesenchymal stem cells, exosomes, clinical drugs, natural products, miRNAs and target molecules. It provides a new idea for the repair of nerve tissue after spinal cord injury. In the future, it is necessary to further study the detailed mechanism of microglia to regulate polarization during spinal cord injury.
Key words: microglia, polarization, spinal cord injury, inflammation, phenotype, angiogenesis, axonal regeneration, review