Iwasaki Yasumasa, Kambayashi Machiko, Asai Masato, Yoshida Masanori, Nigawara Takeshi, Hashimoto Kozo
Department of Endocrinology, Metabolism, and Nephrology, Kochi Medical School, Kochi University, Nankoku 783-8505, Japan.
J Diabetes Complications. 2007 Jan-Feb;21(1):56-62. doi: 10.1016/j.jdiacomp.2006.02.001.
Diabetes mellitus is frequently associated with coagulation disorders such as coronary heart disease and stroke. We aimed to clarify the molecular mechanism whereby hyperglycemia causes the procoagulant state. HuH7 human hepatocyte cells were treated with high glucose alone or in combination with proinflammatory cytokines, and the effects on the activity of the transcription factor nuclear factor kappa-B (NF-kappaB), which mediates the expression of acute-phase and coagulation-related genes, were examined. The results showed that increasing the medium glucose concentration from 3 to 24 mM significantly enhanced NF-kappaB-luciferase activity by 40% in the presence of insulin. The effect was promoter specific and not mimicked by comparable hyperosmolality with L-glucose. Proinflammatory cytokines such as interleukin-1 and tumor necrosis factor-alpha (TNF-alpha) also stimulated NF-kappaB-dependent transcription and showed an additive effect with high glucose. Similar effects were obtained on acute-phase or coagulation/fibrinolysis-related gene promoters such as fibrinogen or plasminogen activator inhibitor-1, all of which are shown to have NF-kappaB-mediated transcription. Finally, pretreatment of the cells with an antioxidant PDTC completely abolished the effect of high glucose and markedly attenuated that of TNF-alpha, suggesting the involvement of reactive oxygen species. These results suggest that (1) high glucose as well as proinflammatory cytokines have positive effects on NF-kappaB-mediated transcription in an additive manner and enhance coagulation-related gene expression and (2) the effects are mediated, at least partly, by the generation of oxidative stress and may be responsible for the high prevalence of thrombotic disorders in the metabolic syndrome with diabetes, hyperinsulinemia, obesity, and/or inflammation.
糖尿病常与冠心病和中风等凝血障碍相关。我们旨在阐明高血糖导致促凝状态的分子机制。将HuH7人肝细胞单独用高糖处理或与促炎细胞因子联合处理,并检测其对介导急性期和凝血相关基因表达的转录因子核因子κB(NF-κB)活性的影响。结果显示,在存在胰岛素的情况下,将培养基葡萄糖浓度从3 mM提高到24 mM可使NF-κB荧光素酶活性显著增强40%。该效应具有启动子特异性,且不能被等渗的L-葡萄糖模拟。白细胞介素-1和肿瘤坏死因子-α(TNF-α)等促炎细胞因子也刺激NF-κB依赖性转录,并与高糖表现出相加效应。在急性期或凝血/纤维蛋白溶解相关基因启动子如纤维蛋白原或纤溶酶原激活物抑制剂-1上也获得了类似的效应,所有这些启动子均显示有NF-κB介导的转录。最后,用抗氧化剂PDTC预处理细胞完全消除了高糖的作用,并显著减弱了TNF-α的作用,提示活性氧的参与。这些结果表明:(1)高糖以及促炎细胞因子以相加方式对NF-κB介导的转录有正向作用,并增强凝血相关基因的表达;(2)这些作用至少部分是由氧化应激的产生介导的,可能是糖尿病、高胰岛素血症、肥胖和/或炎症的代谢综合征中血栓性疾病高患病率的原因。