Brevilin A Ameliorates Acute Lung Injury and Inflammation Through Inhibition of NF-κB Signaling via Targeting IKKα/β

Acute lung injury (ALI) is life-threatening disease characterized by uncontrolled inflammatory response. IKK alpha/beta, the key kinases in the activation of NF-kappa B pathway, are implicated in inflammatory pulmonary injury, and represent attractive targets for ALI therapy. Brevilin A (BVA) is a sesquiterpene lactone from Centipeda minima, a Chinese herb used to treat inflammatory diseases. This study aims to investigate the inhibition of BVA on ALI, with focus on clarifying the molecular mechanisms involved in BVA-mediated anti-inflammatory activity in macrophages. Briefly, BVA significantly inhibited the production of NO and PGE(2) by suppressing iNOS and COX2 expression, and suppressed the mRNA expression of IL-1 beta, IL-6, and TNF alpha in LPS/IFN gamma-stimulated RAW264.7 macrophages. The anti-inflammatory activity of BVA was further confirmed in LPS/IFN gamma-stimulated BMDMs and TNF alpha/IFN gamma-exposed RAW264.7 cells. In vivo, BVA effectively attenuated LPS-induced lung damage, inflammatory infiltration, and production of pro-inflammatory cytokines, including MPO, IL-1 beta, IL-6, TNF alpha, and PGE(2). Mechanistically, BVA could covalently bind to the cysteine 114 of IKK alpha/beta, and effectively inhibiting the activity and function of IKK alpha/beta, thereby resulting in the suppression of phosphorylation and degradation of I kappa B alpha and the subsequent activation of NF-kappa B signaling. Furthermore, pretreatment of DTT, a thiol ligand donor, significantly abolished BVA-mediated effects in LPS/IFN gamma-stimulated RAW264.7 cells, suggesting the crucial role of the electrophilic alpha, beta-unsaturated ketone of BVA on its anti-inflammatory activity. These results suggest that BVA ameliorates ALI through inhibition of NF-kappa B signaling via covalently targeting IKK alpha/beta, raising the possibility that BVA could be effective in the treatment of ALI and other diseases harboring aberrant NF-kappa B signaling.