Xanthohumol combined with swimming ameliorates hepatic injury in rats with metabolic associated fatty liver disease

Abstract

BACKGROUND: Xanthohumol is a natural polyphenol that exhibits biological activities such as antioxidant and anti-inflammatory properties. Recently, it has been found to potentially improve lipid metabolism disorders. As an aerobic exercise, swimming can effectively regulate body energy metabolism and reduce hepatic fat accumulation. However, the intervention effect and mechanism of their combined application on metabolic associated fatty liver disease remain unclear. OBJECTIVE: To investigate the effect of xanthohumol combined with swimming on the ferroptosis pathway mediated by nuclear factor erythroid 2-related factor 2 in rats with metabolic associated fatty liver disease. METHODS: Rats were randomly divided into seven groups: control group, model group, exercise group, low-, medium-, and high-dose xanthohumol, and combination groups, with 12 rats in each group. The rats in control group were fed with normal feed, while the rats in other groups were used to prepare metabolic associated fatty liver disease models. Rats in the exercise and combination groups received swimming training once a day, 6 days per week, for a total of 8 weeks. Rats in other groups were raised quietly. Rats in the low-, medium-, and high-dose xanthohumol groups were intragastrically administered 2 mL of 25, 50, and 100 mg/(kg·d) xanthohumol, respectively; rats in the combination group were intragastrically administered 2 mL of 100 mg/(kg·d) xanthohumol while undergoing swimming training; other groups were intragastrically administered 2 mL of 0.3% sodium carboxymethyl cellulose, for a total of 8 weeks. After treatment, serum alanine aminotransferase, aspartate aminotransferase, and free fatty acid levels were measured; hepatic lipid accumulation was observed by hematoxylin-eosin staining; hepatic malondialdehyde and reduced glutathione levels were detected according to kit instructions; hepatic ferrous ion content was measured by microassay; Western blot was used to detect the protein expression of nuclear factor erythroid 2-related factor 2, Kelch-like ECH-associated protein 1, and glutathione peroxidase 4 in liver tissue; RT-qPCR was used to detect the mRNA levels of ferroptosis-related genes (glutathione peroxidase 4, solute carrier family 7 member 11, ferritin heavy chain 1, ferroportin 1, and cationic transport regulator-like protein 1). RESULTS AND CONCLUSION: Compared with the exercise group and high-dose xanthohumol group, the combination group showed lower serum alanine aminotransferase, aspartate aminotransferase, and free fatty acid levels, improved liver morphology, decreased hepatic malondialdehyde level, increased reduced glutathione level, decreased hepatic ferrous ion content, increased protein expression of nuclear factor erythroid 2-related factor 2 (nuclear) and glutathione peroxidase 4, decreased protein expression of Kelch-like ECH-associated protein 1, increased mRNA levels of glutathione peroxidase 4, solute carrier family 7 member 11, ferritin heavy chain 1, and ferroportin 1, and decreased mRNA level of cationic transport regulator-like protein 1 (P < 0.05). These findings suggest that xanthohumol combined with swimming may improve hepatic injury in rats with metabolic associated fatty liver disease by regulating the ferroptosis pathway mediated by nuclear factor erythroid 2-related factor 2.

1. Introduction

Metabolic associated fatty liver disease (MAFLD) is one of the most prevalent chronic liver diseases worldwide, with its pathological progression closely linked to lipid metabolism disorders, oxidative stress imbalance, and inflammatory cascades [1-4]. Recent studies have revealed that ferroptosis, an iron-dependent lipid peroxidation-driven cell death mode, plays a critical role in the pathogenesis of liver diseases including MAFLD [5]. Under normal physiological conditions, hepatic iron homeostasis and antioxidant defense systems maintain a dynamic balance. However, when metabolic stress such as a high-fat diet disrupts this balance, hepatic iron overload can catalyze reactive oxygen species generation via the Fenton reaction, triggering membrane lipid peroxidation chain reactions and ultimately leading to ferroptosis [4,6-7]. This death mode not only directly causes hepatocyte damage but also exacerbates MAFLD progression through the release of damage-associated molecular patterns, forming a 'ferroptosis-inflammation' cascade amplification effect [8]. Therefore, inhibiting ferroptosis may become a new strategy for the future treatment of MAFLD.

In the ferroptosis regulatory network, the nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein 1 (Keap1)/glutathione peroxidase 4 (GPX4) pathway constitutes the core defense mechanism [9]. Under oxidative stress conditions, Nrf2 dissociates from the Keap1 inhibitory complex and translocates to the nucleus, initiating the expression program of antioxidant response element-driven genes. Among these, GPX4, as a key effector molecule, can reduce lipid peroxides by consuming reduced glutathione, thereby blocking the ferroptosis process. Studies have shown that Nrf2 nuclear translocation障碍 and GPX4 downregulation are common in liver tissues of MAFLD animal models [10-11], suggesting that restoring Nrf2-mediated negative regulation of ferroptosis is a potential target for MAFLD prevention and treatment.