Department of Health and Nutritional Biotechnology, Asia University, Taichung, Taiwan.
J Agric Food Chem. 2011 May 25;59(10):5263-71. doi: 10.1021/jf104003y. Epub 2011 Apr 26.
Several lines of evidence indicate that inflammation and endothelial cell dysfunction are important initiating events in atherosclerosis. Tumor necrosis factor-α (TNF-α), a pro-inflammatory cytokine, induces the expression of cell adhesion molecules and results in monocyte adherence and atheromatous plaque formation. Andrographolide (AP) is a major bioactive diterpene lactone in Andrographis paniculata that has anti-inflammatory activity. A previous study demonstrated the role of heme oxygenase 1 (HO-1) in the inhibition of TNF-α-induced ICAM-1 expression by AP. The present study investigated the effect of AP on the IKK/NF-κB signaling pathway, which mediates TNF-α-induced ICAM-1 expression in EA.hy926 cells. Similar to the previous study, AP inhibited TNF-α-induced ICAM-1 mRNA and protein levels, its expression on the cell surface, and subsequent adhesion of HL-60 cells to EA.hy926 cells. AP inhibited TNF-α-induced κB inhibitor (IκB) kinase (IKK) and IκBα activation, p65 nuclear translocation, NF-κB and DNA binding activity, and promoter activity of ICAM-1. Although AP increased the intracellular cAMP concentration and induced the phosphorylation of cAMP response element-binding protein (CREB), knocking down CREB protein expression by transfecting the cells with CREB-specific small interfering RNA did not relieve the inhibition of ICAM-1 expression by AP. Taken together, these results suggest that AP down-regulates TNF-α-induced ICAM-1 expression at least in part via attenuation of activation of NF-κB in EA.hy926 cells rather than through activation of CREB. The results suggest that AP may have potential as a cardiovascular-protective agent.
有几条证据表明，炎症和内皮细胞功能障碍是动脉粥样硬化的重要起始事件。肿瘤坏死因子-α（TNF-α）是一种促炎细胞因子，可诱导细胞粘附分子的表达，导致单核细胞黏附和动脉粥样斑块形成。穿心莲内酯（AP）是穿心莲中的一种主要生物活性二萜内酯，具有抗炎活性。先前的研究表明血红素加氧酶 1（HO-1）在 AP 抑制 TNF-α诱导的 ICAM-1 表达中起作用。本研究探讨了 AP 对 IKK/NF-κB 信号通路的影响，该通路介导 TNF-α诱导的 EA.hy926 细胞中 ICAM-1 的表达。与先前的研究相似，AP 抑制了 TNF-α诱导的 ICAM-1 mRNA 和蛋白水平、细胞表面表达以及随后 HL-60 细胞与 EA.hy926 细胞的黏附。AP 抑制了 TNF-α诱导的κB 抑制剂（IκB）激酶（IKK）和 IκBα的激活、p65 核易位、NF-κB 和 DNA 结合活性以及 ICAM-1 的启动子活性。尽管 AP 增加了细胞内 cAMP 浓度并诱导 cAMP 反应元件结合蛋白（CREB）的磷酸化，但通过转染细胞用 CREB 特异性小干扰 RNA 敲低 CREB 蛋白表达并不能缓解 AP 对 ICAM-1 表达的抑制作用。综上所述，这些结果表明，AP 通过减弱 NF-κB 在 EA.hy926 细胞中的激活，至少部分地下调了 TNF-α诱导的 ICAM-1 表达，而不是通过激活 CREB。这些结果表明 AP 可能具有作为心血管保护剂的潜力。
