Water extract of Glycyrrhiza uralensis Fisch.enhanced the activation of RAW264.7 cells through TLR4 signaling pathway / 中华微生物学和免疫学杂志

ABSTRACT

Objective To investigate the effects of water extract of Glycyrrhiza uralensis Fisch.(GUWE) on the activation of RAW264.7 cells and the possible mechanism.Methods RAW264.7 cells were treated with GUWE containing different concentrations of polysaccharide (10, 50, 100, 500 μg/ml).Viability of these cells was analyzed by MTT assay.Phagocytic activity and surface molecules expressed on these cells were detected by flow cytometry.Levels of cytokines were analyzed by ELISA.Western blot assay was performed to analyze the activation of key molecules in TLR4 signaling pathway.Results GUWE at the concentration of 500 μg/ml significantly decreased the viability of RAW264.7 cells, but significantly increased the viability of RAW264.7 cells at concentrations of 50 μg/ml and 100 μg/ml.GUWE significantly enhanced the phagocytic activity of RAW264.7 cells as well as the expression of cytokines and costimulatory molecules in a dose-dependent manner.Further analysis indicated that the activation of RAW264.7 cells induced by GUWE was suppressed by TLR4 inhibitor.Moreover, GUWE enhanced the phosphorylation of NF-kB p65 and TLR4 downstream mitogen-activated protein kinases (MAPKs) including p38, extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK).Conclusion This study indicates that GUWE promotes the activation of RAW264.7 cells through TLR4 signaling pathway.