Geniposide alleviates inflammation by suppressing MeCP2 in mice with carbon tetrachloride-induced acute liver injury and LPS-treated THP-1 cells

Geniposide (GP), an iridoid glucoside extracted from Gardenia jasminoides Ellis fruits, has been used as a herbal medicine to treat liver and gall bladder disorders for many years. However the mechanism of anti-inflammatory is largely unknown. In this study, GP significantly attenuated inflammation in acute liver injury (ALI) mice model and in lipopolysaccharide (LPS)-induced THP-1 cells. It was demonstrated that GP obviously decreased the expression of Methyl-CpG binding protein 2 (MeCP2) in vivo and in vitro. Knockdown of MeCP2 with siRNA suppressed the expressions of IL-6 and TNF-α, while over-expression of MeCP2 had a proinflammatory effect on the expression of IL-6 and TNF-α in LPS-induced THP-1 cells. Mechanistically, it was indicated that GP had anti-inflammatory effects at least in part, through suppressing MeCP2. Interestingly, GP could attenuate expressions of Sonic hedgehog (Shh) and GLIS family zinc finger 1 (GLIS1) but increase Ptched1 (PTCH1) expression. Similar findings were also demonstrated at the protein level by siRNA MeCP2. Furthermore, over-expression of MeCP2 obviously increased Shh and GLIS1 expressions but reduced PTCH1 expression. Taken together, GP may serve as an effective modulator of MeCP2-hedgehog pathway (Hh)-axis during the pathogenesis of inflammation. Our findings shed light on the potential therapeutic feature of GP in recovering inflammatory diseases.