Interference of interleukin-1β mediated by lentivirus promotes functional recovery of spinal cord contusion injury in rats via the PI3K/AKT signaling pathway

Background: Spinal cord contusion (SCC) results in a series of pathophysiologic consequences such as edema, apoptosis, and inflammation. However, inflammation may also be beneficial for the recovery of motor function after SCC, but the underlying mechanisms remain incompletely elucidated. Interleukin-1 beta (IL-1β) is a pro-inflammatory factor that has synergistic effects with other inflammatory factors to aggravate spinal cord injury. Inflammatory factors have been found to activate the serine/threonine-specific protein kinase, protein kinase B (AKT) and to inhibit cell survival, but it is not clear whether inflammation upregulates the expression of IL-1β in the rat model of SCC and subsequently interferes in the phosphatidylinositol-3-kinase (PI3K)/AKT signaling pathway. Therefore, this study explored whether IL-1β affects the recovery of motor function in spinal cord injury by interfering with the PI3K/AKT signaling pathway. Method: SCC rats were established by the Allen method. The Basso Beattie Bresnahan (BBB) scoring was used to assess motor function in the spinal cord of injured rats. Quantitative polymerase chain reaction and Western blot were used to determine the expression of genes and proteins of IL-1β, PI3K, and AKT1. Immunohistochemistry and immunofluorescence were used to locate and detect IL-1β and AKT1 proteins in spinal cord tissue. To further explore the underlying mechanism of IL-1β, lentivirus was constructed by RNA interfering (RNAi) technique to inhibit the expression of IL-1β, and bioinformatics was applied to show the relationship between IL-1β and AKT1. Results: BBB scores decreased after SCC, and IL-1β and AKT1 was located in the cytoplasm of spinal cord anterior horn neurons. In the early stage of SCC, the expression level of IL-1β gene and protein in the experimental group was higher than that in the sham operated group. At the same time, expression of the AKT1 gene decreased. After expression of IL-1β mediated by lentivirus was inhibited, BBB scores increased significantly, and spinal cord motor function improved. Bioinformatic analysis revealed a relationship between IL-1β and AKT1. In addition, AKT1 gene expression was upregulated and PI3K expression was unchanged in the PI3K/AKT signaling pathway. Conclusion IL-1β not only exacerbates the inflammatory response after SCC, but also interferes with motor function. Inhibition of IL-1β may promote recovery of spinal cord injury by upregulating AKT1 in the PI3K/AKT signaling pathway, which provides a new perspective for future clinical practice in treating spinal cord injury