Acetylbritannilactone suppresses lipopolysaccharide-induced vascular smooth muscle cell inflammatory response

To investigate the mechanism of action by which a new anti-inflammatory active compound, 1-O-acetylbritannilactone (ABL) isolated from Inula britannica-F., inhibits inflammatory responses in vascular smooth muscle cells (VSMCs). Enzyme immunoassay was used to measure the levels of prostandin E2 (PGE2) production. Immunocytochemistry staining and Western blot analysis were performed to detect the nuclear translocation of nuclear factor-κB (NF-κB) p65 and the expression of IκB-α, pIκB-α and cyclooxygenase-2 (COX-2). Electrophoretic mobility shift assays (EMSA) were used to detect DNA-binding activity of NF-κB in VSMCs. ABL (5, 10, 20 μmmol/l) had several concentration-dependent effects, including inhibition of lipopolysaccharide (LPS)-induced PGE2 production and COX-2 expression, and blockade of NF-κB activation and translocation. These effects were owing to reductions in IκB-α phosphorylation and degradation induced by LPS. In addition, ABL directly inhibited the binding of active NF-κB to specific DNA cis-element. These results indicate that ABL is a potent inhibitor of LPS-stimulated VSMC inflammatory responses through blockade of NF-κB activity and inhibition of inflammatory gene COX-2 expression.