Withaferin A inhibits tumor necrosis factor-α-induced expression of cell adhesion molecules by inactivation of Akt and NF-κB in human pulmonary epithelial cells

We here investigated the functional effect of withaferin A on airway inflammation and its action mechanism. Withaferin A inhibited the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in human lung epithelial A549 cells stimulated with tumor necrosis factor-α (TNF-α), resulting in the suppression of leukocyte adhesion to lung epithelial A549 cells. In addition, withaferin A inhibited TNF-α-induced expression of adhesion molecules (ICAM-1 and VCAM-1) protein and mRNA in a dose-dependent manner. Withaferin A prevented DNA binding activity of nuclear factor-κB (NF-κB) and nuclear translocation of NF-κB. It also inhibited phosphorylation of Akt and extracellular signal-regulated kinase (ERK), which are upstream in the regulation of adhesion molecules by TNF-α. Furthermore, withaferin A inhibited U937 monocyte adhesion to A549 cells stimulated by TNF-α, suggesting that it may inhibit the binding of these cells by regulating the expression of critical adhesion molecules by TNF-α. Taken together, these results suggest that withaferin A inhibits cell adhesion through inhibition of ICAM-1 and VCAM-1 expression, at least in part, by blocking Akt and down-regulating NF-κB activity.