Defining the oxidative stress-related mechanisms by which activation of the transcription factor Nrf2 arrests and resolves liver fibrosis

定义转录因子 Nrf2 激活阻止和解决肝纤维化的氧化应激相关机制

• 批准号: MR/T014644/1
• 负责人: John Hayes
• 金额: $ 258.09万
• 依托单位: University of Dundee
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FT014644%2F1
• 关键词: Defining; oxidative; stress; related; mechanisms

Repetitive wound healing in the liver results in fibrosis leading to scarring and, if severe, to cirrhosis. It is a serious condition that can lead to liver failure, and liver cancer. Liver cirrhosis arises due to a variety of causes including viruses, alcohol, auto-immunity, metabolic conditions and obesity-related liver damage. There has been a huge increase in cirrhosis, which poses an enormous challenge to our NHS. Most alarmingly, there is currently no effective therapy for liver fibrosis, except transplantation. Recently we discovered that by activating a major regulator of intracellular antioxidant systems, called Nrf2, we were able to arrest and/or reverse established and ongoing liver fibrosis in the mouse. The purpose of this project is to determine how activation of Nrf2 changes the formation and removal of liver scar tissue. The scarring is laid down by specific cells in the liver called hepatic stellate cells (HSCs), and is removed by immune cells recruited into the liver called macrophages. An important feature of liver fibrosis is that its initiation, perpetuation and progression involve cooperation between different cell types within the liver, including the immune cells, which is governed by production of various signalling molecules that allow communication between the different cell types. One such class of molecule are oxidants, called reactive oxygen species (ROS), that trigger pro-fibrotic and pro-inflammatory signalling cascades. As the development of liver fibrosis involves production by HSCs of ROS, which trigger redox signalling that causes their differentiation into collagen-secreting myofibroblasts that proliferate, we envisage that activation of Nrf2 in HSCs blocks synthesis of fibrous scar tissue in the liver by inducing antioxidant genes that inactivate ROS and block redox signalling. ROS also simulate inflammatory responses in macrophages recruited into the liver, so rather than allowing them to kill HSCs and digest extracellular scar material, they cause more damage, we envisage that activation of Nrf2 in these immune cells dampens inflammation and promotes resolution of fibrosis by inducing antioxidant genes that inactivate ROS and block redox signalling, allowing the cell to resolve the fibrosis. To evaluate these hypotheses, we will use transgenic mice to explore whether pharmacological and genetic activation of Nrf2 in HSCs of mice with ongoing liver fibrosis arrests synthesis of fibrous scar protein in the liver by blunting redox signalling and will identify which of the genes regulated by Nrf2 contributes to inhibition of fibrogenesis. In a similar manner, we will use transgenic mice to explore whether pharmacological and genetic activation of Nrf2 in immune cells of mice that have liver fibrosis but in which liver injury has ceased, accelerates removal of the fibrous scar by blunting redox signalling, and will identify which of the genes regulated by Nrf2 contribute to resolution of fibrosis. To examine the clinical significance of results we will examine the abundance of Nrf2 in HSCs isolated from the livers of patients with cirrhosis and evaluate whether activation of Nrf2 induces target genes, suppresses ROS levels and inhibits the synthesis of fibrous protein. Also, we will take macrophages from the blood of patients with cirrhosis and see if activation of Nrf2 induces Nrf2-target genes, suppresses ROS levels and promotes an anti-inflammatory and pro-resolving cell type. Lastly, we will evaluate the value of Nrf2 measurements in the liver of patients with liver disease to predict clinical outcome and shed light on the molecular processes that lead to liver fibrosis. Thus, we will measure Nrf2 levels in archived liver sections from patients with liver disease and assess whether Nrf2 is downregulated and expression of its target genes suppressed in severe cases of liver cirrhosis, and explore whether proteins that are known to be negative regulators of Nrf2 are upregulated.

肝脏的反复伤口愈合会导致纤维化，从而导致疤痕，如果严重的话，会导致肝硬化。这是一种严重的疾病，可能导致肝衰竭和肝癌。肝硬化是由多种原因引起的，包括病毒、酒精、自身免疫、代谢状况和肥胖相关的肝损伤。肝硬化患者数量大幅增加，这对我们的国民医疗服务体系（NHS）构成了巨大的挑战。最令人担忧的是，目前除了移植之外，尚无有效的肝纤维化治疗方法。最近我们发现，通过激活细胞内抗氧化系统的主要调节因子 Nrf2，我们能够阻止和/或逆转小鼠中已形成和正在进行的肝纤维化。该项目的目的是确定 Nrf2 的激活如何改变肝脏疤痕组织的形成和去除。疤痕是由肝脏中称为肝星状细胞 (HSC) 的特定细胞形成的，并被招募到肝脏中的称为巨噬细胞的免疫细胞去除。肝纤维化的一个重要特征是，其发生、持续和进展涉及肝脏内不同细胞类型（包括免疫细胞）之间的合作，免疫细胞是由各种信号分子的产生控制的，这些信号分子允许不同细胞类型之间的通讯。其中一类分子是氧化剂，称为活性氧 (ROS)，它会触发促纤维化和促炎症信号级联反应。由于肝纤维化的发展涉及HSC产生ROS，这会触发氧化还原信号，导致其分化为增殖的胶原蛋白分泌肌成纤维细胞，我们设想HSC中Nrf2的激活通过诱导抗氧化基因使ROS失活并阻断氧化还原信号来阻止肝脏中纤维疤痕组织的合成。 ROS还模拟招募到肝脏中的巨噬细胞的炎症反应，因此它们不会杀死HSC并消化细胞外疤痕物质，而是会造成更多损伤，我们设想这些免疫细胞中Nrf2的激活会通过诱导抗氧化基因使ROS失活并阻断氧化还原信号传导来抑制炎症并促进纤维化的消退，从而使细胞能够解决纤维化。为了评估这些假设，我们将使用转基因小鼠来探索持续性肝纤维化小鼠 HSC 中 Nrf2 的药理和遗传激活是否通过减弱氧化还原信号传导来阻止肝脏中纤维疤痕蛋白的合成，并将确定 Nrf2 调节的哪些基因有助于抑制纤维发生。以类似的方式，我们将使用转基因小鼠来探索在患有肝纤维化但肝损伤已停止的小鼠的免疫细胞中Nrf2的药理学和遗传激活是否通过减弱氧化还原信号来加速纤维疤痕的去除，并将确定哪些受Nrf2调节的基因有助于纤维化的解决。为了检验结果的临床意义，我们将检测从肝硬化患者肝脏中分离的 HSC 中 Nrf2 的丰度，并评估 Nrf2 的激活是否会诱导靶基因、抑制 ROS 水平并抑制纤维蛋白的合成。此外，我们将从肝硬化患者的血液中提取巨噬细胞，观察 Nrf2 的激活是否会诱导 Nrf2 靶基因、抑制 ROS 水平并促进抗炎和促消退细胞类型。最后，我们将评估肝病患者肝脏中 Nrf2 测量值的价值，以预测临床结果并揭示导致肝纤维化的分子过程。因此，我们将测量肝病患者存档肝切片中的Nrf2水平，评估在严重肝硬化病例中Nrf2是否下调及其靶基因表达是否受到抑制，并探讨已知的Nrf2负调节蛋白是否上调。

项目成果

NRF2 and the Ambiguous Consequences of Its Activation during Initiation and the Subsequent Stages of Tumourigenesis.

• DOI: 10.3390/cancers12123609
• 发表时间: 2020-12-02
• 期刊: Cancers
• 影响因子: 5.2
• 作者: Robertson H;Dinkova-Kostova AT;Hayes JD
• 通讯作者: Hayes JD

Omaveloxolone (SkyclarysTM) for patients with Friedreich's ataxia.

• DOI: 10.1016/j.tips.2023.03.005
• 发表时间: 2023-06-01
• 期刊: Trends in pharmacological sciences
• 影响因子: 13.8
• 作者: Dayalan Naidu, Sharadha;Dinkova-Kostova, Albena T
• 通讯作者: Dinkova-Kostova, Albena T