α-Lactalbumin Peptide Asp-Gln-Trp Ameliorates Hepatic Steatosis and Oxidative Stress in Free Fatty Acids-Treated HepG2 Cells and High-Fat Diet-Induced NAFLD Mice by Activating the PPARα Pathway

Diet, oxidative stress and MAFLD: a mini review

Globally, metabolic dysfunction-associated fatty liver disease (MAFLD), also known as non-alcoholic fatty liver disease (NAFLD) or metabolic dysfunction-associated steatotic liver disease (MASLD), is a common chronic liver disease. The progression of MAFLD leads to a vicious cycle in which oxidative stress results from the disease that is augmenting de-novo lipid levels and increases steatosis. Most non-enzymatic antioxidants are present in food. Therefore, the present review summarizes the findings of studies on food-derived antioxidants and presents an oxidative stress-related regulatory network in MAFLD, offering new ideas for MAFLD prevention and treatment.

Hericium erinaceus Protein Alleviates High-Fat Diet-Induced Hepatic Lipid Accumulation and Oxidative Stress In Vivo

Dietary interventions with food-derived natural products have emerged as a promising strategy to alleviate obesity. This study aims to investigate the anti-obesity effect of Hericium erinaceus protein (HEP) and its underlying mechanism. Our results demonstrated that HEP exhibited excellent radical scavenging activity in vitro. In vivo, HEP intervention reduced pancreatic lipase activity in the intestine and enhanced fat excretion, thereby inhibiting the absorption of dietary fats. Meanwhile, HEP ameliorated the body weight and organ indexes, dyslipidemia, insulin resistance, hepatic steatosis, and liver oxidative stress injuries in obese mice. The results of real-time PCR (qRT-PCR) and Western blot analyses indicated that HEP upregulated the expression of peroxisome proliferator-activated receptor α (PPARα), subsequently upregulated the expression of liver fatty acid oxidation-related genes (lipoprotein lipase (LPL), carnitine palmitoyltransferase 1a (CPT-1a), and acyl-CoA oxidase 1 (ACOX1)) and downregulated the expression of lipogenesis-related genes (sterol regulatory element-binding protein-1c (SREBP-1c), stearoyl-coenzyme A desaturase 1 (SCD-1), and fatty acid synthase (FASN)), thereby ameliorating lipid metabolism disorders. Therefore, these findings demonstrated that HEP exerted protective effects on lipid metabolism disorders by activating the PPARα pathway, indicating its potential as a dietary supplement for the prevention and amelioration of obesity.

Bioactive proteins and antioxidant peptides from Litsea cubeba fruit meal: Preparation, characterization and ameliorating function on high-fat diet-induced NAFLD through regulating lipid metabolism, oxidative stress and inflammatory response

Non-alcoholic fatty liver disease (NAFLD) plays an increasingly significant threat to human health. In this study, the processing by-products of Litsea cubeba fruit meal were defatted by ultrasound-assisted methods, then the acetone-precipitated protein of L. cubeba (LCP) was obtained and structural analysis was performed. LCP was hydrolyzed by a two-step sequential hydrolysis method using alcalase and papain. Subsequently, antioxidant peptide fraction (IV2) was isolated and identified from the resultant hydrolysate through membrane ultrafiltration, Sephadex G-15 chromatography, and liquid chromatograph mass spectrometer (LC-MS). Animal experimentation indicated the potential of IV2 to mitigate hepatic steatosis. Moreover, IV2 could effectively reduce oxidative stress-induced damage by modulating the Keap1-Nrf2 pathway to activate downstream heme oxygenase-1 (HO-1) and NAD(P) H quinone oxidoreductase 1 (NQO1). Integrating metabolomics and transcriptomics revealed enrichment in pathways associated with glycerolipid metabolism and fatty acid β-oxidation, suggesting the principal mechanisms underlying IV2's ameliorative effects on NAFLD. Transcriptome sequencing identified 3092 up-regulated and 3010 down-regulated genes following IV2 treatment. Interaction analyses based on different lipid compositions (DELs) and differentially expressed genes (DEGs) indicated that IV2 primarily alleviated hepatic steatosis by modulating peroxisome proliferator-activated receptor α (PPAR-α) related pathways, thereby augmenting fatty acid β-oxidation within liver cells. These results indicate that IV2 shows potential in improving high-fat diet (HFD)-induced NAFLD, with improved fatty acid β-oxidation and reduced triglyceride biosynthesis emerging as underlying mechanisms.

Cyclosporine-A induced cytotoxicity within HepG2 cells by inhibiting PXR mediated CYP3A4/CYP3A5/MRP2 pathway

Cyclosporine-A (CsA) is currently used to treat immune rejection after organ transplantation as a commonly used immunosuppressant. Liver injury is one of the most common adverse effects of CsA, whose precise mechanism has not been fully elucidated. Pregnane X receptor (PXR) plays a critical role in mediating drug-induced liver injury as a key regulator of drug and xenobiotic clearance. As a nuclear receptor, PXR transcriptionally upregulates the expression of drug-metabolizing enzymes and drug transporters, including cytochrome P4503A (CPY3A) and multidrug resistance-associated protein 2 (MRP2). Our study established CsA-induced cytotoxic hepatocytes in an in vitro model, demonstrating that CsA dose-dependently increased the aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) level secreted in the HepG2 cell supernatant, as well as viability and oxidative stress of HepG2 cells. CsA also dose-dependently decreased the PXR, CYP3A4, CPY3A5, and MRP2 levels of HepG2 cells. Mechanistically, altering the expression of PXR, CYP3A4, CYP3A5, and MRP2 affected the impact of CsA on AST and LDH levels. Moreover, altering the expression of PXR also changed the level of CYP3A4, CPY3A5, and MRP2 of HepG2 cells treated by CsA. Our presented findings provide experimental evidence that CsA-induced liver injury is PXR tightly related. We suggest that PXR represents an attractive target for therapy of liver injury due to its central role in the regulation of the metabolizing enzymes CYP3A and MRP2-mediated bile acid transport and detoxification.