Abstract
Curcumin has several therapeutic properties such as anti-inflammatory effect. Heme oxygenase-1 (HO-1) has been showed to have cytoprotective effects in some pathological conditions. However, the role of HO-1 in anti-inflammatory effect of curcumin is unknown. In this study, we investigate whether the anti-inflammatory effect of curcumin in vascular may be involved in the activation of HO-1. New Zealand white rabbits were fed regular control diet or control diet added with 0.3% curcumin (wt/wt) for four weeks. Acute vascular inflammation of rabbits was induced by putting a collar on the left common carotid artery for 24 hours. HO-1 inhibitor and siRNA were used to investigate the role of HO-1 in the anti-inflammatory effect of curcumin in collared vascular. We also explored the mechanism of curcumin-induced activation of HO-1 in vitro. The serum bilirubin and vascular, liver, and spleen HO-1 mRNA levels were significantly increased in curcumin-treated rabbits. The vascular inflammation was significantly decreased in the curcumin-treated animals compared with the control. Treatment of the rabbits with an inhibitor of HO or HO-1 siRNA to knock down the carotid artery HO-1 abolished the ability of curcumin to inhibit vascular inflammation. Treatment of cultured human artery endothelial cells with curcumin induced the HO-1 expression through the activation of nuclear factor-E2-related factor 2 (Nrf2) and an antioxidant responsive element via the p38 MAPK signalling pathway. In conclusion, curcumin inhibits vascular inflammation in vivo and in vitro through the activation of HO-1.