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

Abstract

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.

Keywords: Enterovirus 71; Glycyrrhizin; Inflammatory response; NF-кB signaling pathway