Mangan Simone, Clancy Paula, Golledge Jonathan
Vascular Biology Unit, School of Medicine, James Cook University, Townsville, Queensland, 4811, Australia.
Thromb Res. 2008;121(6):827-34. doi: 10.1016/j.thromres.2007.08.007. Epub 2007 Sep 14.
Thrombomodulin (TM) is an important anti-coagulant protein that is down-regulated on endothelial cells overlying atherosclerotic plaques. We investigated the effects of the peroxisome proliferator-activated receptor (PPAR) ligands, fenofibrate and rosiglitazone, on the expression of TM ex vivo by advanced carotid atheromas, and in vitro by endothelial cells.
Adjacent carotid atheroma biopsies were incubated in vehicle control or PPAR ligand in explant culture for 4 days. Human aortic endothelial cells were incubated with PPAR ligands in vitro. TM expression was measured by Western blotting and flow cytometry. TM activity was assessed by generation of activated protein C.
The PPAR-alpha activator, fenofibrate, up-regulated total TM expression within carotid explants by 1.7-fold (P<0.001) with no effect on activity. Rosiglitazone treatment had no effect on protein levels but reduced activity by 73% of the control (P<0.05). We noted disparate effects of PPAR ligands in atheroma samples from different patients and postulated that the response of endothelial cells to medication was influenced by the atheromatous environment. Incubation of human aortic endothelial cells with fenofibrate alone led to a dose-dependent increase in TM expression (P<0.05), however, in the presence of oxidized LDL a dose-dependent reduction in TM expression was induced by fenofibrate (P<0.05).
The ability of fenofibrate to increase endothelial cell and carotid atheroma TM protein expression suggests a potential therapeutic role for this medication. The response to PPAR ligands likely varies depending on the exact constituents of individual atherosclerotic plaques, such as the relative amount of oxidized LDL.
血栓调节蛋白（TM）是一种重要的抗凝血蛋白，在动脉粥样硬化斑块上方的内皮细胞上表达下调。我们研究了过氧化物酶体增殖物激活受体（PPAR）配体非诺贝特和罗格列酮对晚期颈动脉粥样硬化斑块离体TM表达以及对内皮细胞体外TM表达的影响。
将相邻的颈动脉粥样硬化斑块活检组织在器官培养中于载体对照或PPAR配体中孵育4天。人主动脉内皮细胞在体外与PPAR配体孵育。通过蛋白质印迹法和流式细胞术测量TM表达。通过生成活化蛋白C评估TM活性。
PPAR-α激活剂非诺贝特使颈动脉外植体中的总TM表达上调1.7倍（P<0.001），对活性无影响。罗格列酮处理对蛋白质水平无影响，但使活性降低至对照的73%（P<0.05）。我们注意到PPAR配体在不同患者的动脉粥样硬化斑块样本中有不同的作用，并推测内皮细胞对药物的反应受动脉粥样硬化环境的影响。单独用非诺贝特孵育人主动脉内皮细胞导致TM表达呈剂量依赖性增加（P<0.05），然而，在存在氧化型低密度脂蛋白的情况下，非诺贝特诱导TM表达呈剂量依赖性降低（P<0.05）。
非诺贝特增加内皮细胞和颈动脉粥样硬化斑块TM蛋白表达的能力表明该药物具有潜在的治疗作用。对PPAR配体的反应可能因个体动脉粥样硬化斑块的确切成分而异，例如氧化型低密度脂蛋白的相对含量。
