Mohib Mohammad Mohabbulla, Rabe Sindy, Nolze Alexander, Rooney Michael, Ain Quratul, Zipprich Alexander, Gekle Michael, Schreier Barbara
Julius-Bernstein-Institute of Physiology, Martin Luther University Halle-Wittenberg, Magdeburger Strasse 6, 06112, Halle (Saale), Germany.
Department of Internal Medicine IV, Jena University Hospital, Friedrich-Schiller-University Jena, Am Klinikum 1, 07747, Jena, Germany.
Cell Commun Signal. 2024 Dec 20;22(1):614. doi: 10.1186/s12964-024-01991-2.
Recent studies suggest a contribution of intrahepatic mineralocorticoid receptor (MR) activation to the development of cirrhosis. As MR blockade abrogates the development of cirrhosis and hypoxia, common during the development of cirrhosis, can activate MR in hepatocytes. But, the impact of non-physiological hepatic MR activation is unknown. In this study, we investigate the impact of hypoxia-induced hepatocyte MR activation as a relevant factor in cirrhosis.
RNA sequencing followed by gene ontology term enrichment analysis was performed on liver samples from rats treated for 12 weeks with or without CCl and for the last four weeks with or without eplerenone (MR antagonist). We investigated if these changes can be mimicked by hypoxia in a human hepatocyte cell line (HepG2 cells) and in primary rat hepatocytes (pRH). In order to evaluate the functional cellular importance, hepatocyte lipid accumulation, glucose consumption, lactate production and mitochondrial function were analyzed.
In cirrhotic liver tissue genes annotated to the GOterm "Monocarboxylic acid metabolic process" (PPARα, PDK4, AMACR, ABCC2, Lipin1) are downregulated. This effect is reversed by the MR antagonist eplerenone in vivo. The alterations are partially mimicked by hypoxia in rat and human hepatocytes in tissue culture. Furthermore, the reduction of mRNA and protein expression of PPARα, PDK4, AMACR, ABCC2 and Lipin1 during hypoxia is prevented by eplerenone in rat and human hepatocytes. Aldosterone, the endogenous MR agonist, did not affect the expression of those proteins in hepatocytes. As those proteins are key regulators of hepatocyte energy homeostasis, we analyzed if hypoxia affected glucose consumption, lactate production and lipid accumulation in HepG2 cells in a MR-mediated manner. All three parameters were affected by hypoxia and were partially normalized by eplerenone.
Our findings suggest that non-physiological MR activation plays a role in the dysregulation of glucose and lipid metabolism in hepatocytes. This leads to an increase in apoptosis, probably resulting in a proinflammatory micromilieu of the hepatic tissue. The enhanced deposition of extracellular matrix contributes to the development of cirrhosis. Therefore, MR antagonists may have therapeutic potential in the treatment of early stages of liver disease due to their direct action in the liver.
最近的研究表明，肝内盐皮质激素受体（MR）激活在肝硬化的发展中起作用。由于MR阻断可消除肝硬化的发展，而缺氧在肝硬化发展过程中很常见，可激活肝细胞中的MR。但是，非生理性肝MR激活的影响尚不清楚。在本研究中，我们调查缺氧诱导的肝细胞MR激活作为肝硬化相关因素的影响。
对用或不用四氯化碳（CCl）处理12周且在最后四周用或不用依普利酮（MR拮抗剂）处理的大鼠肝脏样本进行RNA测序，随后进行基因本体术语富集分析。我们研究了这些变化是否可以在人肝细胞系（HepG2细胞）和原代大鼠肝细胞（pRH）中被缺氧模拟。为了评估细胞功能的重要性，分析了肝细胞脂质积累、葡萄糖消耗、乳酸产生和线粒体功能。
在肝硬化肝组织中，注释为GO术语“单羧酸代谢过程”（PPARα、PDK4、AMACR、ABCC2、Lipin1）的基因下调。MR拮抗剂依普利酮在体内可逆转这种作用。在组织培养中，大鼠和人肝细胞中的缺氧部分模拟了这些改变。此外，依普利酮可防止大鼠和人肝细胞在缺氧期间PPARα、PDK4、AMACR、ABCC2和Lipin1的mRNA和蛋白质表达降低。内源性MR激动剂醛固酮不影响肝细胞中这些蛋白质的表达。由于这些蛋白质是肝细胞能量稳态的关键调节因子，我们分析了缺氧是否以MR介导的方式影响HepG2细胞中的葡萄糖消耗、乳酸产生和脂质积累。所有这三个参数均受缺氧影响，依普利酮可使其部分恢复正常。
我们的研究结果表明，非生理性MR激活在肝细胞葡萄糖和脂质代谢失调中起作用。这导致细胞凋亡增加，可能导致肝组织的促炎微环境。细胞外基质沉积增加有助于肝硬化的发展。因此，MR拮抗剂因其在肝脏中的直接作用，可能在肝病早期治疗中具有治疗潜力。
