厚朴酚增加TNF-α處理之內皮細胞與Apo-E缺乏小鼠動脈的heme oxygenase-1表現

Abstract

厚朴酚是從Magnolia officinalis萃取出的化合物，長久以來被用來治療發熱、頭痛、焦慮、腹瀉及氣喘。厚朴酚已有諸多藥理應用，包括治療缺血再灌注 損傷，也發現厚朴酚具有很強的抗氧化力及抗發炎的功效。血基質氧化酶-1可以將血基質分解成一氧化碳、鐵離子及膽綠素，在細胞中有重要的抗氧化能力。血基質氧化酶藉由防止細胞凋亡保護內皮細胞，可以調節血管緊張度，抑制血管壁的發炎反應，表示血基質氧化酶-1可能具有治療心血管疾病的潛能，所以本研究目的在於探討厚朴酚對TNF-α刺激人類主動脈內皮細胞內的血基質氧化酶-1是否有調節作用，並探討其相關訊息傳遞路徑，也以Apo-E缺乏小鼠模擬動脈硬化病變模式，探討厚朴酚是否能降低TNF-α刺激Apo-E缺乏小鼠體內的氧化壓力以及對於血基質氧化酶-1的表現是否有調控的作用。實驗結果顯示：投予TNF-α可抑制人類主動脈內皮細胞中血基質氧化酶-1的表現，而先以厚朴酚處理再投予TNF-α，則可回復受到TNF-α抑制的血基質氧化酶-1表現。實驗結果也發現TNF-α刺激會增加人類主動脈內皮細胞中ERK、JNK、p38的磷酸化，以厚朴酚處理細胞，再用TNF-α刺激，則可降低受到TNF-α刺激所增加的ERK、JNK、p38的磷酸化。實驗進一步發現加入PD98059 (ERK 抑制劑) 及SP600125 (JNK 抑制劑)，再加入TNF-α刺激會降低血基質氧化酶-1的表現；而加入SB203580 (p38抑制劑) 處理，再以TNF-α刺激後則有上升的趨勢。在轉錄因子部分：發現TNF-α刺激會增加人類主動脈內皮細胞中NF-κB的表現，而先以厚朴酚處理，再以TNF-α刺激則會抑制NF-κB的表現。另外以Apo-E缺乏小鼠動脈血管壁切片中發現，單獨以TNF-α刺激組，其ROS的表現量有增加的現象，而先給予厚朴酚再以TNF-α刺激組，ROS的表現量有下降的趨勢，單獨給予厚朴酚組，ROS表現量也有下降的現象。另外，在組織免疫染色部分，給予厚朴酚再受到TNF-α刺激組，其血管斑塊處的血基質氧化酶-1表現會上升。綜合上述實驗結果得知：厚朴酚會調節TNF-α所抑制血基質氧化酶-1的表現，顯示厚朴酚對動脈硬化或發炎反應的治療有很大助益。

Magnolol, a compound extracted from Magnolia officinalis, has long been used for the treatment of fever, headache, anxiety, diarrhoea, asthma, and stroke. It also exerts antithrombotic, anti-inflammatory and analgesic effects. A number of other pharmacological effects of magnolol have also been demonstrated, including prevention of ischemic-reperfusion injury, and, most importantly, strong antioxidant activity. More recently, it has been shown to effectively prevent neointimal hyperplasia in the balloon-injured aorta of cholesterol-fed rabbits. Heme oxygenase-1 (HO-1), an enzyme degrading heme to carbon monoxide, iron, and biliverdin, has been recognized as playing a crucial role in cellular defense against stressful conditions, not only related to heme release. HO-1 protects endothelial cells from apoptosis, is involved in blood-vessel relaxation regulating vascular tone, attenuates inflammatory response in the vessel wall, and participates in blood-vessel formation by means of angiogenesis and vasculogenesis. The purpose of this study was aimed to examine the effects of TNF-a on HO-1 expression in HAECs, and the effect of magnolol as a potential therapeutic agent, and the mechanisms involved in the effects of magnolol or TNF-a on HO-1 expression. In the present study, TNF-α treatment reduced HO-1 expression in HAECs as well as in Apo-E deficient mice. Magnolol increased the expression of HO-1 in TNF-α-treated HAECs. Phosphorylation studies of ERK1/2, JNK, and p38, three subgroups of mitogen-activated protein kinases (MAPKs) demonstrated that magnolol suppressed TNF-α-induced ERK1/2, JNK, and p38 phosphorylation. In the transcription level, magnolol suppressed TNF-a-treated NF-кB expression. In addition, magnolol effectively attenuated TNF-a-induced ROS production in Apo-E deficient mice. These results suggest that magnolol has a therapeutic potential in cardiovascular diseases through the upregulation of HO-1 expression.