RESUMEN
BACKGROUND:Previous animal studies have shown that riluzole can inhibit neuroinflammatory response after spinal cord injury and promote functional recovery in injured rats,but the study on whether it can regulate the expression of nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)inflammasome in the acute stage is lacking. OBJECTIVE:To observe whether riluzole can reduce microglial pyroptosis and promote functional recovery after spinal cord injury by modulating NLRP3 inflammasome through animal experiments,histological experiments and molecular biology experiments. METHODS:Female SD rats were divided into sham operation,model and riluzole groups,with 12 rats in each group.In addition to the sham operation group,T10 spinal cord injury was conducted in rats.The model group was treated with intraperitoneal administration of riluzole with solvent cyclodextrin.The riluzole group was treated with a 4 mg/kg dose of riluzole injection.The effect of riluzole on motor function recovery was assessed using the BBB score and inclined plane test.The recovery of sensory-evoked potential and motor-evoked potential was measured by electrophysiology.Hematoxylin-eosin staining was used to evaluate spinal cord tissue repair.The regulatory effects of riluzole on NLRP3,Caspase-1 and gasdermin D protein expression in spinal cord tissues were detected by western blot assay.ELISA was utilized to detect the expression levels of inflammatory factors interleukin-1β and interleukin-18.The effects of riluzole on the expression of NLRP3,Caspase-1,gasdermin D and interleukin-1β in microglial cells of the injured spinal cord were determined by immunofluorescence staining. RESULTS AND CONCLUSION:(1)At 35 days after spinal cord injury,BBB score and inclined plane test score in the riluzole group were higher than those in the model group(P<0.05).(2)At 3 days after spinal cord injury,the protein expressions of NLRP3,cleaved Caspase-1,gasdermin D-N(N-terminal domain),interleukin-1β,and interleukin-18 in the spinal cord homogenate of the riluzole group were significantly lower than those of the model group(P<0.05).(3)At 3 days after spinal cord injury,the fluorescence intensity of NLRP3,Caspase-1,gasdermin D and interleukin-1β in the riluzole group was significantly lower than that in the model group(P<0.05).(4)At day 35 after spinal cord injury,hematoxylin-eosin staining showed that the area of spinal cord injury in the riluzole group was smaller than that in the model group.Electrophysiological tests showed that the latency periods of sensory-evoked potential and motor-evoked potential in the riluzole group were shorter than those in the model group,and the latency period of wave amplitude in the riluzole group was higher than that in the model group.(5)These results suggest that riluzole can promote the repair of injured spinal cord tissue,promote the repair of nerve conduction function,and further promote the recovery of motor function in rats with spinal cord injury,which may be achieved through the regulation of NLRP3 inflammasome and the reduction of microglial pyroptosis.
RESUMEN
BACKGROUND:Neuroinflammation is an important factor leading to secondary spinal cord injury,and microglia/macrophage pyroptosis is a significant part of post-spinal cord injury neuroinflammation.Studies have shown that microglia/macrophage undergoes pyroptosis after spinal cord injury,but the regulatory mechanism of circular RNA(circRNA)in microglia/macrophage pyroptosis after spinal cord injury remains unclear. OBJECTIVE:To investigate the role and mechanism of circRNA0005512 in regulating microglia/macrophage pyroptosis after spinal cord injury. METHODS:Female Wistar rats were divided into sham group and spinal cord injury group.Motor function was evaluated using the Basso,Beattie,and Bresnahan(BBB)scale.Cavity volume was assessed by hematoxylin-eosin staining.Differential expression of circRNA in spinal cord tissue was screened using RNA-sequencing and circ0005512 was validated by real-time PCR.Immunofluorescence,western blot assay,ELISA,and real-time PCR were performed to detect cell pyroptosis in the rats and lipopolysaccharide-induced microglial cell line HAPI cell models.Gene knockdown was used to confirm the regulatory role of circRNA0005512 in microglia/macrophage pyroptosis. RESULTS AND CONCLUSION:(1)Seven days after spinal cord injury,evident cavities were observed at the injury site.Immediately after spinal cord injury,the motor function of rats was completely lost.Over time,the motor function of rats in the spinal cord injury group gradually partially recovered,and there was a significant difference in BBB scores compared to the sham group.(2)Circ0005512 was significantly upregulated according to the results of the RNA-sequencing and confirmed in both the animal and cell models.(3)Immunofluorescence,western blot assay,real-time PCR,and ELISA confirmed the significant upregulation of cell pyroptosis markers(NLRP3,GSDMD,and caspase-1)in spinal cord injury tissue and lipopolysaccharide-induced HAPI cells.(4)In the cell model,knockdown of circ0005512 resulted in significantly decreased levels of cell pyroptosis marker-NLRP3.(5)The results above indicate that circ0005512 promotes pyroptosis in microglia/macrophages after spinal cord injury.