Glycyrrhizin Modulates the Inflammatory Response Induced by Ev71 Infection by Targeting the NF-κB pathway

Background: Previous research has demonstrated that glycyrrhizin exhibits antioxidant, anti-inflammatory and antiapoptotic characteristics. In this study, RD cells were infected with Enterovirus 71 (EV71) and a cell model of viral infection was established to explore the effect of glycyrrhizin on the inflammatory response triggered by EV71 infection of RD cells and its potential mechanism. Materials and Methods: In this study, the cells were categorized into 4 groups: the uninfected Normal control group, the EV71-infected RD group, the glycyrrhizin treatment group and the PDTC group (which received the NF-κB pathway inhibitor PDTC). The expression levels of EV71's VP1, 3D, P65 and phosphorylated-P65 (p-P65) proteins in each group were detected by western blotting. Using ELISA, the amounts of pro-inflammatory cytokines TNF-α, IL-18 and IL-1β in the RD cells' growth media were measured. Results: Compared with the uninfected regular control group, the EV71-infected RD group had increased levels of inflammatory factors IL-1β, IL-18 and TNF-α and the expression of p-P65 protein was significantly upregulated. However, in the presence of 50 µM glycyrrhizin or PDTC, the levels of IL-1β, IL-18 and TNF-α were notably decreased in the p-P65 protein's expression, which was markedly down-regulated in the culture medium. Conclusion: Glycyrrhizin appears to mitigate the inflammatory response triggered by EV71 infection in RD cells by inhibiting the NF-κB signalling pathway.