Immunomodulatory Activity And Mechanism Of Taraxacum Officinale Wigg.in Microglia Based On HO-1

Taraxacum officinale Wigg.,a kind of medicine food homologous plant with a long history,is widely distributed in Asia,Europe and other parts of the world.It is reported that T.officinale has many biological and pharmacological activities,including anti-cancer,weight-loss and liver protection.However,the effects and mechanism of T.officinale on neuroinflammation have not been reported.The aim of this study was to establish neuroinflammatory models in vitro and in vivo by lipopolysaccharide induced microglia and lipopolysaccharide injected in lateral ventricles of mice.To study the protective effect of T.officinale on microglia and mice brain,and to explore its protective mechanism,and to provide theoretical basis for its application in neurodegenerative diseases.In this study,LC-MS/MS was used to analyze the ethanol extract of T.officinale(A-TOW).In LPS induced microglia,the experimental group was divided into control group,LPS induced group,100 ?g/ml A-TOW group(LPS + 100 ?g/ml A-TOW),200 ?g/ ml A-TOW group(LPS + 200 ?g/ml A-TOW),300 ?g/ml A-TOW group(LPS + 300 ?g/ml A-TOW),400 ?g/ml A-TOW group(LPS + 400 ?g/ml A-TOW),T.officinale extract was pretreated for 12 hours and then induced by LPS together with the model group for 18 hours.Then,the pro-inflammatory factors released by the cells were detected by the ELISA kit,and the expression of heme oxygenase-1(HO-1),Nrf2,nuclear transcription factor-?B(NF-?B)related protein in the cells was detected by Western blot to study the anti-inflammatory mechanism of T.officinale extract.In vivo experiments of neuroinflammation induced by injection of lipopolysaccharide into lateral ventricle,the mices were divided into three groups: control group,injection group of LPS into lateral ventricle,group of A-TOW(injection of LPS into lateral ventricle),28 days after administration of A-TOW,injection of lateral ventricle after the last administration.After 24 hours,the brain homogenate inflammatory cytokines was detected by ELISA.The activation of microglia was observed by histological staining and immunohistochemistry.To evaluate the protective effect of T.officinale on LPS induced neuroinflammation in mouse brain.The results showed that the A-TOW mainly contained caffeic acid,cichoric acid,luteolin and luteolin.The results of cell experiment showed that A-TOW could inhibit the level of inflammatory factors induced by LPS in a concentration dependent manner.In addition,A-TOW also inhibited the nuclear translocation of nuclear factor p65 induced by LPS.It was also found that T.officinale could significantly promote Nrf2 expression in the nucleus and up-regulate HO-1.The results of si-HO-1 and HO-1 inhibitors showed that T.officinale inhibited the expression of inflammatory factors through HO-1 pathway.LPS injection into the lateral ventricles of mice can obviously cause the inflammation of the hippocampus and the activation of microglia.In vivo experiments showed that T.officinale could inhibit the inflammation of hippocampus.The results of immunohistochemistry and Western blotting showed that the expression of Iba-1 was significantly reduced,which indicated that T.officinale could improve the brain neuroinflammation induced by LPS by inhibiting the activation of microglia.The above results showed that T.officinale could inhibit LPS induced neuroinflammation and thus protect the brain.The protective effect was partly through Nrf2/HO-1 and inhibiting the activation of NF-?B.