The Study On The Mechanism Of Luteolin's Anti-inflammatory Effect Through Inhibition Of HMGB1 Release

Sepsis is systemic inflammatory response syndrome induced by infection,which is mainly caused by Gram negative bacteria.Lipopolysaccharide(LPS)has a pivotal role in the toxicity of Gram negative bacteria.LPS acts on macrophages inducing the expression of cytokines and adhesion molecules that contribute to the inflammatory response.High mobility group B-1(HMGB1),originally identified as a high conserved DNA-binding factor in the nucleus,translocates from nucleus to cytosol and then exocytose.When HMGB1 releases from macrophage in response to infectious agents,it can serve as a cytokine contributed to high lethality in sepsis.Luteolin,a flavone that widely exists among the plants,has potent anti-inflammatory properties.However,the molecular mechanism beneath luteolin mediated immune modulation remains unclear.Previous studies by our laboratory showed that luteolin is an inhibitor of Hsp90,and we studied luteolin's anti-inflammatory mechanism on this basis.The experimental methods used in this study are as follows:MTT was used to measure luteolin's effect on cell viability.ELISA was used to measure luteolin's effect on the release of HMGB1 and other cytokines;Immunofluorescence was performed to observe the translocation of HMGB1;The expression and protein level of the proteins in the correlative signal pathway was measured by western blot.Animal experiment was performed to observe luteolin's effect on the lethality rate of endotoxic shock mice.Here,we reported that luteolin with a concentration of 0-100?M did not significantly influence the L02,HEK293,RAW264.7 and HUVEC cell viability;Luteolin effectively protected mice from LPS-induced lethality,and reduced TNF-?and NO release from macrophages.Luteolin effectively inhibited the release of HMGB1,which is a late mediator of inflammation.Because of the close relation between HMGB1 release and the lethality rate of endotoxic shock,we further studied the mechanism of luteolin's inhibition on HMGB1 release.We found that luteolin decreased the c-Jun and Akt level in the cell by inhibiting the chaperon activities of Hsp90 to inhibit HMGB1 nuclear export and release and HMGB1-induced inflammatory cascade.Research conclusions:As an inhibitor of Hsp90,luteolin inhibited HMGB1 release significantly and decreased the lethality rate of the endotoxic shock mice,thus may act a potential therapeutic reagent for treating inflammatory diseases.