Eplerenone, a mineralocorticoid receptor inhibitor, reduces cirrhosis associated changes of hepatocyte glucose and lipid metabolism.

Abstract

Background: 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.

Methods: RNA sequencing followed by gene ontology term enrichment analysis was performed on liver samples from rats treated for 12 weeks with or without CCl₄ 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.

Results: 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.

Conclusion: 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.