1-o-acetylbritannilactone Inhibits Inflammatory Response by Suppressing NF-κB Activation

Abstract: Immunocytochemistry and Western blot analysis were adopted to measure the nuclear translocation of NF-κB p65 and the expression of IκB-α， cyclo-oxygenase-2 (COX-2). Electrophoretic mobility shift assay (EMSA) was performed to detect DNA-binding activity of NF-κB in vascular smooth muscle cells (VSMC) pretreated with ABL. Western blot and immunocytochemistry analysis showed that lipopolysaccharide (LPS) treatment resulted in increasing nuclear translocation of NF-κB p65， and declining levels of IκB-α in VSMC. However， 1-o-acetylbritannilactone (ABL) pretreatment inhibited the nuclear translocation of p65 and degradation of IkB-a induced by LPS， and the inhibitory effect of ABL was concentration-dependent. LPS increased the binding of nuclear extracts from VSMC induced by LPS to double strands oligonucleotide probe containing NF-κB binding site using EMSA. The shift bands were abolished when a 100-fold excess of unlabeled NF-kB oligonucleotide probe was included. Pretreatment with ABL significantly reduced the nuclear level of NF-κB and declined the binding activity of nuclear extracts with DNA probe induced by LPS. Furthermore， ABL consequentially inhibited the expression of NF-κB-dependent COX-2 gene induced by LPS. These results suggest that ABL may be one anti-inflammatory drug which inhibits the expression of COX-2 gene by blocking NF-κB activation and thus suppresses the inflammatory response to LPS in VSMC.

CSTR: 32200.14.cjcb.2007.02.0020