Yang Tian-Lun, Chen Mei-Fang, Luo Bai-Lin, Xie Qi-Ying, Jiang Jun-Lin, Li Yuan-Jian
Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha, Hunan, 410078, China.
Naunyn Schmiedebergs Arch Pharmacol. 2005 May;371(5):401-7. doi: 10.1007/s00210-005-1060-8. Epub 2005 May 25.
Previous investigations have demonstrated that endogenous inhibitors of nitric oxide synthase (NOS), such as asymmetric dimethylarginine (ADMA), contribute importantly to endothelial dysfunction, and that fenofibrate has a protective effect on the endothelium in rats treated with low-density lipoprotein (LDL) by reducing ADMA levels. In the present study, we explored further the possible mechanism underlying inhibition of ADMA generation by fenofibrate in cultured human umbilical vein endothelial cells (HUVECs). Endothelial injury was induced in cultured HUVECs by incubation with oxidative LDL (ox-LDL) and the levels of ADMA, lactate dehydrogenase (LDH), NO and tumour necrosis factor-alpha (TNF-alpha) in the conditioned medium were measured. Cell viability and the activity of dimethylarginine dimethylaminohydrolase (DDAH) and nuclear factor-kappaB (NF-kappaB) in the cultured HUVECs were also determined. Incubation of HUVECs with ox-LDL (100 microg/ml) for 24 h markedly elevated ADMA, LDH and TNF-alpha in the conditioned medium and significantly increased the activity of NF-kappaB, concomitantly with a significant decrease in the activity of DDAH and the content of NO. Pretreatment with fenofibrate (3, 10 or 30 microM) significantly inhibited the increases in ADMA, LDH and TNF-alpha, attenuated the decreased levels of NO and the decreased activity of DDAH and prevented the activation of NF-kappaB. Similar effects were observed in the presence of pyrrolidine dithiocarbamate (PDTC, 10 microM), an antagonist of NF-kappaB. The beneficial effects of fenofibrate on cultured endothelial cells were abolished by MK-886, a specific peroxisome proliferator-activated receptor-alpha (PPARalpha) antagonist. The present results suggest that fenofibrate inhibits ox-LDL-induced endothelial cell damage by decreasing ADMA and increasing DDAH activity, and the protective effects of fenofibrate on endothelial cells may be related to reduction of NF-kappaB activity by activation of the PPARalpha receptor.
先前的研究表明，一氧化氮合酶（NOS）的内源性抑制剂，如不对称二甲基精氨酸（ADMA），对内皮功能障碍起重要作用，并且非诺贝特通过降低ADMA水平，对用低密度脂蛋白（LDL）处理的大鼠内皮具有保护作用。在本研究中，我们进一步探讨了非诺贝特在培养的人脐静脉内皮细胞（HUVECs）中抑制ADMA生成的潜在机制。通过与氧化型低密度脂蛋白（ox-LDL）孵育，在培养的HUVECs中诱导内皮损伤，并测量条件培养基中ADMA、乳酸脱氢酶（LDH）、一氧化氮（NO）和肿瘤坏死因子-α（TNF-α）的水平。还测定了培养的HUVECs中的细胞活力、二甲基精氨酸二甲氨基水解酶（DDAH）和核因子-κB（NF-κB）的活性。用ox-LDL（100μg/ml）孵育HUVECs 24小时，显著提高了条件培养基中ADMA、LDH和TNF-α的水平，并显著增加了NF-κB的活性，同时DDAH的活性和NO的含量显著降低。用非诺贝特（3、10或30μM）预处理可显著抑制ADMA、LDH和TNF-α的增加，减轻NO水平的降低和DDAH活性的降低，并防止NF-κB的激活。在存在NF-κB拮抗剂吡咯烷二硫代氨基甲酸盐（PDTC，10μM）的情况下观察到类似的效果。非诺贝特对培养的内皮细胞的有益作用被特异性过氧化物酶体增殖物激活受体-α（PPARα）拮抗剂MK-886消除。目前的结果表明，非诺贝特通过降低ADMA和增加DDAH活性来抑制ox-LDL诱导的内皮细胞损伤，并且非诺贝特对内皮细胞的保护作用可能与通过激活PPARα受体降低NF-κB活性有关。
