POSSIBLE MOLECULAR MECHANISMS FOR PORTAL HYPERTENSION AND THE IMPLICATIONS ON ITS TREATMENT

门静脉高压的可能分子机制及其治疗的意义

基本信息

批准号：
14571204
负责人：
TOMIKAWA Morimasa
金额：
$ 1.79万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14571204/
关键词：
portal hypertension hyperdynamic circulation intrahepatic vascular resistance endothelial nitric oxide synthase (eNOS)hepatic stellate cell (HSC)nitric oxide (NO)Rho kinase Akt シグナルトランスダクション ROCK RHOkinase阻害剤肝線維化肝硬変治療

项目摘要

Portal hypertension is characterized by the hyperdynamic circulation in the splanchnic organs as well as by the increased intrahepatic vascular resistance. Excessive nitric oxide production by endothelial nitric oxide synthase (eNOS) and elevated tumor necrosis factor-α (TNF-α) are implicated in the development of the systemic hyperdynamic circulation and portal hypertensive (PHT) gastropathy. The increased intrahepatic vascular resistance is associated with a contraction of hepatic stellate cells (HSCs) and a reduction of nitric oxide (NO) production in sinusoidal endothelial cells. HSCs also plays a major role in hepatic fibrogenesis, leading to portal hypertension. However, the molecular mechanisms for these phenomena remain to be elucidated. The aims of our studies are to determine the molecular basis for the hyperdynamic circulation of splanchnic organs and the intrahepatic microcirculatory disturbance.Our present study demonstrates for the first time that : (1)eNOS activation in … More PHT gastric mucosa is due to : (a)increased phosphorylation of eNOS at serine 1177 ; (b)activation of the PI 3-kinase/Akt signaling pathway ; (c)enhanced binding of Akt to eNOS ; and, (2)TNF-α neutralizing antibody reduces phosphorylation of eNOS and activation of the PI 3-kinase/Akt signaling pathway in PHT gastric mucosa to the normal levels. In PHT gastric mucosa elevated TNF-α induces phosphorylation of eNOS at serine 1177 (required for its activation) via activation of the PI 3-kinase/Akt signaling pathway.PHT gastric mucosa is highly susceptible to injury caused by alcohol, aspirin and other noxious factors, but the mechanism is not fully understood. Since such mucosal injury is initially mediated by oxygen free radicals, and since MAP kinase (ERK2) protects against cellular stress and induces cell proliferation, we postulated that oxidative stress-induced ERK2 activation is defective in PHT gastric mucosa. Here we demonstrated that in PHT gastric mucosa, ERK2 activation by oxidative stress is impaired. This impairment is mediated by overexpression of MAP kinase phosphatase-1 (MKP-1), which results from an underlying oxidative state, and is ameliorated by inhibiting MKP-1. Supplementing vitamin E, a free radical scavenger, normalizes MKP-1 expression in PHT gastric mucosa and completely reverses the increased susceptibility to alcohol injury. Our findings provide the molecular mechanism for the pathophysiology of PHT gastropathy and should expedite developing effective non-invasive therapy.In the rat model of liver fibrosis induced by dimethlnitrosamine(DMN), fasudil (a novel specific inhibitor of Rho kinase) conceptation orally reduced fibrosis of the liver in 3 weeks. HSCs activation induced by liver injuary, as shown by the decreased the number of activated HSCs (_-SMA positive cells) and the protein expression_-SMA was also reduced in 3weeks. Moreover, oral administration of fasudil significantly reduced portal pressure of DMN rats at both 1 and 3 weeks, compared to DMN alone. This study indicates that oral administration of fasudil reduce extracellular matrix deposition and portal hypertension in vivo. In vitro experiments showed 1_M fasudil induced HSC apoptosis. The reduction of liver fibrosis and portal hypertension is likely to be induced by inhibition of HSC activation and apoptosis. These points will impact on the new therapiutic drug for cirrhotic patients.The present study demonstrates in cirrhotic rats by the bile duct ligation that (1)Rho kinase signaling and its dawnstream _-SMA protein is upregulated; and (2)the long-term inhibition of Rho kinase with fasudil leads to the reduced contraction of HSCs and the upregulation of eNOS phosphorylation and prevents the microcirculatory disturbance, finally improving the portal hypertension in liver cirrhosis. Less

门静脉高血压的特征是方案器官中的高动力循环以及增加的epatitic内血管耐药性。内皮一氧化氮合酶（ENOS）和肿瘤坏死因子-α（TNF-α）产生过多的一氧化氮产生，在系统性超基因循环和门静脉高血压（PHT）胃病的发展中实施。增加的epatitic血管耐药性与肝星状细胞（HSC）的收缩和正弦内皮细胞中一氧化氮（NO）产生的减少有关。 HSC在肝纤维发生中也起着主要作用，导致门静脉高血压。但是，这些现象的分子机制仍有待阐明。我们研究的目的是确定示意图器官和e脚内微循环灾难的高动力循环的分子基础。我们目前的研究首次表明：（1）在…更多的PHT胃粘膜中的ENOS激活是由于：（a）丝氨酸1177上eNOS的磷酸化增加；（b）PI 3-激酶/AKT信号通路的激活；（c）增强了Akt与eNOS的结合；（2）TNF-α中和抗体降低了eNOS的磷酸化以及PI 3-激酶/Akt信号通路的激活，而PHT胃粘膜中的磷酸化降低了正常水平。在PHT胃粘膜中，TNF-α升高可通过激活PI 3-激酶/Akt信号通路诱导丝氨酸1177（其激活所需的eNOS）磷酸化。pht胃粘膜非常易于受到损伤而受到损伤，这是由于酒精，阿司匹林和其他不良因素而引起的，但该机构却完全不了解。由于这种粘膜损伤最初是由氧自由基介导的，并且MAP激酶（ERK2）可预防细胞应激并诱导细胞增殖，因此我们发布了氧化应激诱导的ERK2激活在PHT胃粘膜中有缺陷。在这里，我们证明在PHT胃粘膜中，氧化应激激活ERK2受损。这种障碍是由MAP激酶磷酸酶-1（MKP-1）的过表达介导的，该磷酸酶-1（MKP-1）是由潜在的氧化态导致的，并通过抑制MKP-1来改善。补充维生素E（一种自由基清除剂）使PHT胃粘膜中的MKP-1表达归一化，并完全逆转了对酒精损伤的易感性增加。我们的发现为PHT胃病的病理生理提供了分子机制，并应加快开发有效的非侵入性疗法。在大鼠二甲硝基胺（DMN）诱导的大鼠肝纤维化模型，Fasudil（Rho激酶的一种新型特异性抑制剂）概念概念的纤维化纤维纤维纤维纤维中的纤维化3周。肝损伤诱导的HSC激活，如激活的HSC的数量（_-SMA阳性细胞）所显示的，并且在3周中也降低了蛋白质表达_-SMA。此外，与仅DMN相比，口服Fasudil在1和3周时显着降低了DMN大鼠的门户压力。这项研究表明，口服Fasudil在体内减少细胞外基质沉积和门静脉高压。体外实验显示1_M Fasudil诱导的HSC凋亡。肝纤维化和门静脉高血压的减少可能是通过抑制HSC激活和凋亡来诱导的。这些点将影响针对肝硬化患者的新治疗药物。目前的研究表明，通过胆管结扎的肝硬化大鼠（1）（1）Rho激酶信号传导及其Dawnstream _-SMA蛋白已更新；（2）长期对Rho激酶的疲劳抑制作用导致HSC的收缩减少和eNOS磷酸化的上调，并防止微循环灾难，最终改善肝硬化肝脏高血压。较少的