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 E-2 (PGE(2)) production. Immunocytochemistry staining and Western blot analysis were performed to detect the nuclear translocation of nuclear factor-kappa B (NF-kappa B) p65 and the expression Of I kappa B-alpha, p kappa B-alpha and cyclooxygenase-2 (COX-2). Electrophoretic mobility shift assays (EMSA) were used to detect DNA-binding activity of NF-kappa B in VSMCs. ABL (5, 10, 20 mu mmol/l) had several concentration-dependent effects, including inhibition of lipopolysaccharide (LPS)-induced PGE(2) production and COX-2 expression, and blockade of NF-kappa B activation and translocation. These effects were owing to reductions in I kappa B-alpha phosphorylation and degradation induced by LPS. In addition, ABL directly inhibited the binding of active NF-kappa B to specific DNA cis-element. These results indicate that ABL is a potent inhibitor of LPS-stimulated VSMC inflammatory responses through blockade of NF-kappa B activity and inhibition of inflammatory gene COX-2 expression. (c) 2007 Elsevier B.V. All rights reserved.