Red yeast rice prevents chronic alcohol-induced liver disease by attenuating oxidative stress and inflammatory response in mice

The Role of Oxidative Stress in Alcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis of Preclinical Studies

Alcoholic Fatty Liver Disease (AFLD) is characterized by the accumulation of lipids in liver cells owing to the metabolism of ethanol. This process leads to a decrease in the NAD+/NADH ratio and the generation of reactive oxygen species. A systematic review and meta-analysis were conducted to investigate the role of oxidative stress in AFLD. A total of 201 eligible manuscripts were included, which revealed that animals with AFLD exhibited elevated expression of CYP2E1, decreased enzymatic activity of antioxidant enzymes, and reduced levels of the transcription factor Nrf2, which plays a pivotal role in the synthesis of antioxidant enzymes. Furthermore, animals with AFLD exhibited increased levels of lipid peroxidation markers and carbonylated proteins, collectively contributing to a weakened antioxidant defense and increased oxidative damage. The liver damage in AFLD was supported by significantly higher activity of alanine and aspartate aminotransferase enzymes. Moreover, animals with AFLD had increased levels of triacylglycerol in the serum and liver, likely due to reduced fatty acid metabolism caused by decreased PPAR-α expression, which is responsible for fatty acid oxidation, and increased expression of SREBP-1c, which is involved in fatty acid synthesis. With regard to inflammation, animals with AFLD exhibited elevated levels of pro-inflammatory cytokines, including TNF-a, IL-1β, and IL-6. The heightened oxidative stress, along with inflammation, led to an upregulation of cell death markers, such as caspase-3, and an increased Bax/Bcl-2 ratio. Overall, the findings of the review and meta-analysis indicate that ethanol metabolism reduces important markers of antioxidant defense while increasing inflammatory and apoptotic markers, thereby contributing to the development of AFLD.

Functional Teas from Penthorum chinense Pursh Alleviates Ethanol-Induced Hepatic Oxidative Stress and Autophagy Impairment in Zebrafish via Modulating the AMPK/p62/Nrf2/mTOR Signaling Axis

Penthorum chinense Pursh (PCP), a medicinal and edible plant, is widely used in many clinical liver diseases. Oxidative stress and autophagy impairment play crucial roles in the pathophysiology of alcoholic liver disease (ALD). Therefore, the aim of this study was to elucidate the mechanism of PCP in attenuating ethanol-induced liver injury. The liver-specific transgenic zebrafish larvae (lfabp: EGFP) at three days post-fertilization (3 dpf) were treated with different concentrations of PCP (100, 50 and 25 μg/mL) for 48 h, after soaked in a 350 mM ethanol for 32 h. Whole-mount oil red O, H&E staining and biochemical kits were used to detect fatty liver function and fat accumulation, western blot (WB) and immunofluorescence were used to determine proteins expression, and RT-qPCR was used to further verify the related gene expression. PCP restored zebrafish liver function. Additionally, PCP (as dose-dependent) blocked the expression of cytochrome P450 2E1 (CYP2E1), the production of intracellular reactive oxygen species (ROS) and alleviated liver fat accumulation and oxidative damage. PCP exerted its hepatoprotective function by downregulating the expression of kelch-like ECH-associated protein 1 (Keap1), up-regulating the expression of nucleus factor-E2-related factor 2 (Nrf2) (transferring to the nucleus), and attenuating systemic oxidative stress. Furthermore, PCP reduced the expression of sequestosome 1 (p62/SQSTM1, p62), Atg13, and Beclin 1, up-regulating autophagy signaling pathway. Taken together, the molecular evidence that PCP protected the ethanol-induced hepatic oxidative stress and autophagy impairment through activating AMPK/p62/Nrf2/mTOR signaling axis.

Rhoifolin Alleviates Alcoholic Liver Disease In Vivo and In Vitro via Inhibition of the TLR4/NF-κB Signaling Pathway

Background: Alcoholic liver disease (ALD) is a common chronic liver disorder worldwide, which is detrimental to human health. A preliminary study showed that the total flavonoids within Citrus grandis “Tomentosa” exerted a remarkable effect on the treatment of experimental ALD. However, the active substances of Citrus grandis “Tomentosa” were not elucidated. Rhoifolin (ROF) is a flavonoid component present in high levels. Therefore, this research aimed to evaluate the hepatoprotective effects of ROF and its possible mechanisms.

Methods: Molecular docking was performed to analyze the binding energy of ROF to the main target proteins related to ALD. Subsequently, mice were fed ethanol (ETH) for 49 days to establish the chronic alcoholic liver injury models. The liver pathological injury, serum aminotransferase levels, and oxidative stress levels in the liver tissue were measured. Human normal hepatocytes (LO2 cells) were incubated with ETH to construct the alcoholic liver cell model. The inflammatory markers and apoptosis factors were evaluated using real-time PCR and flow cytometry. Finally, the effects of ROF on the CYP2E1 and NF-κB signaling pathways were tested in vitro and in vivo.

Results: Molecular docking results demonstrated that ROF was able to successfully dock with the target proteins associated with ALD. In animal studies, ROF attenuated ETH-induced liver damage in mice by decreasing the serum concentrations of AST and ALT, reducing the expression of inflammatory cytokines, and maintaining antioxidant balance in the liver tissue. The in vitro experiments demonstrated that ROF suppressed ETH-induced apoptosis in LO2 cells by promoting Bcl-2 mRNA and inhibiting Bax mRNA and caspase 3 protein expression. ROF decreased the level of LDH, ALT, AST, ROS, and MDA in the supernatant; induced the activity of GSH and SOD; and inhibited TNF-α, IL-6, and IL-1β expression levels. Mechanistically, ROF could significantly downregulate the expression levels of CYP2E1, TLR4, and NF-κB phosphorylation.

Conclusion: This study indicates that ROF is the active component within the total flavonoids, which may alleviate ETH-induced liver injury by inhibiting NF-κB phosphorylation. Therefore, ROF may serve as a promising compound for treating ALD.