Ampelopsin Attenuates Lipopolysaccharide-induced Inflammatory Response Through The Inhibition Of The NF-?B And JAK2/STAT3 Signaling Pathways In Microglia

Objectives:Microglia are innate immune cells in the central nervous system(CNS).In the homeostatic state,microglia are indispensable to many cellular functions,including immune surveillance of the CNS environment,clearance of damaged neurons and debris,and tissue repair.Microglia are activated following exposure to diverse stimuli,such as ?-amyloid,pathogens,lipopolysaccharide(LPS)and neuron damage.The extensive activated microglia-mediated local inflammation contributes to neuronal injury through the release of pro-inflammatory and cytotoxic factors,including interleukin IL-1?,IL-6,tumor necrosis factor-?(TNF-?),monocyte chemotactic protein-1(MCP-1),nitric oxide(NO),and prostaglandin E2(PGE2).Microglia-mediated neurologic inflammation plays an important role in exacerbating ischemic brain injury,which makes it a promising target for therapeutic strategies in ischemic stroke.In southern China,Ampelopsis grossedentata(vine tea)is consumed as a functional beverage and its compounds exert many bioactive functions.Amp is the major constituent of vine tea.Numerous studies have revealed that Amp has many biological activities,such as anti-cancer,anti-oxidative,anti-microbial,anti-HIV infection properties,and cough relieving effects.In the present study,we investigated the effects and the underlying mechanisms of Ampelopsin(Amp)on modulating microglia-mediated inflammation in LPS-induced microglia.Methods:The present study investigated whether Ampelopsin(Amp),a type offlavanonol derivative from Ampelopsis grossedentata,may exert an anti-inflammatory effect on lipopolysaccharide(LPS)-induced BV2 and primary microglia cells.Real-time PCR,Western blotting and ELISA was used to test the expression of pro-inflammatory mediators.In addition,we examined the potential underlying mechanisms of Amp,including the MAPK,NF-?B,and JAK2/STAT3 signaling pathways.Results:We found that pre-treatment of microglia cells with Amp before LPS with a non-cytotoxic concentration range decreased the production of nitric oxide(NO)and prostaglandin E2(PGE2).Amp also suppressed the expression of inducible nitric oxide synthase(iNOS)and cyclooxygenase-2(COX-2)at the mRNA and protein levels.In addition,LPS-induced production of pro-inflammatory cytokines such as IL-1?,IL-6,and tumor necrosis factor-a(TNF-a)was obviously reduced by Amp.Our mechanistic study indicated that Amp suppressed LPS-induced activation of the I?B/NF-?B inflammation pathway without affecting changes in the phosphorylation levels of mitogen-activated protein kinases(MAPKs)in BV2 cells.Amp markedly reduced the phosphorylation levels of JAK2-STAT3 and STAT3 nuclear translocation.Conclusions:Amp can suppress the LPS-induced inflammatory response of microglial cells,which may be associated with the decreased activity of NF-?B,p38and JNK.