The Absence of Nrf2 Enhances NF-κB-Dependent Inflammation following Scratch Injury in Mouse Primary Cultured Astrocytes

It has been proved that Nrf2 depletion enhances inflammatory process through activation of NF-κB in the brain after TBI, but little is known about the relationship between Nrf2 and NF-κB in astrocytes after TBI. Hence, we used primary cultured astrocytes from either Nrf2 wildtype or knockout mice to study the influence of Nrf2 on the activation of NF-κB and expression of proinflammatory cytokines in a model of TBI in vitro. Primary cultured astrocytes were scratched to mimic the traumatic injury in vitro. Then the DNA-binding activity of NF-κB was evaluated by EMSA. The mRNA and protein levels of TNF-α, IL-1β, IL-6, and MMP9 were also evaluated. Gelatin zymography was performed to detect the activity of MMP9. The activity of NF-κB and expression of proinflammatory cytokines mentioned above were upregulated at 24 h after scratch. The expression and activity of MMP9 were also elevated. And such tendency was much more prominent in Nrf2 KO astrocytes than that in WT astrocytes. These results suggest that the absence of Nrf2 may induce more aggressive inflammation through activation of NF-κB and downstream proinflammatory cytokines in astrocytes.