β-Lapachone suppresses neuroinflammation by modulating the expression of cytokines and matrix metalloproteinases in activated microglia

Background: β-lapachone (β-lap) is a natural naphthoquinone compound isolated from the lapacho tree (tabebuia sp.),and it has been used for treatment of rheumatoid arthritis,infection,and cancer. in the present study,we investigated whether β-lap has anti-inflammatory effects under in vitro and in vivo neuroinflammatory conditions. methods: the effects of β-lap on the expression of inducible nitric oxide synthase (inos),cytokines,and matrix metalloproteinases (mmps) were examined in lipopolysaccharide (lps)-stimulated bv2 microglial cells and rat primary microglia by elisa,reverse transcription polymerase chain reaction (rt-pcr),and western blot analysis. microglial activation and the expression levels of proinflammatory molecules were measured in the lps-injected mouse brain by immunohistochemistry and rt-pcr analysis. the detailed molecular mechanism underlying the anti-inflammatory effects of β-lap was analyzed by electrophoretic mobility shift assay,reporter gene assay,western blot,and rt-pcr analysis. results: β-lap inhibited the expression of inos,proinflammatory cytokines,and mmps (mmp-3,mmp-8,mmp-9) at mrna and protein levels in lps-stimulated microglia. on the other hand,β-lap upregulated the expressions of anti-inflammatory molecules such as il-10,heme oxygenase-1 (ho-1),and the tissue inhibitor of metalloproteinase-2 (timp-2). the anti-inflammatory effect of β-lap was confirmed in an lps-induced systemic inflammation mouse model. thus,β-lap inhibited microglial activation and the expressions of inos,proinflammatory cytokines,and mmps in the lps-injected mouse brain. further mechanistic studies revealed that β-lap exerts anti-inflammatory effects by inhibiting mapks,pi3k/akt,and nf-κb/ap-1 signaling pathways in lps-stimulated microglia. β-lap also inhibited reactive oxygen species (ros) production by suppressing the expression and/or phosphorylation of nadph oxidase subunit proteins,such as p47phox and gp91phox. the anti-oxidant effects of β-lap appeared to be related with the increase of ho-1 and nqo1 via the nrf2/anti-oxidant response element (are) pathway and/or the pka pathway. conclusions: the strong anti-inflammatory/anti-oxidant effects of β-lap may provide preventive therapeutic potential for various neuroinflammatory disorders. © 2015 lee et al.