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Metabolic dysfunction-associated steatotic liver disease (MASLD) is the leading cause of chronic liver disease that affects over 30% of the world's population. For decades, the heterogeneity of non-alcoholic fatty liver disease (NAFLD) has impeded our understanding of the disease mechanism and the development of effective medications. However, a recent change in the nomenclature from NAFLD to MASLD emphasizes the critical role of systemic metabolic dysfunction in the pathophysiology of this disease and therefore promotes the progress in the pharmaceutical treatment of MASLD. In this review, we focus on the mechanism underlying the abnormality of hepatic lipid metabolism in patients with MASLD, and summarize the latest progress in the therapeutic medications of MASLD that target metabolic disorders. [ABSTRACT FROM AUTHOR]

The coronavirus disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). At present, the COVID-19 has been prevalent worldwide for more than a year and caused more than four million deaths. Liver injury was frequently observed in patients with COVID-19. Recently, a new definition of metabolic dysfunction associated fatty liver disease (MAFLD) was proposed by a panel of international experts, and the relationship between MAFLD and COVID-19 has been actively investigated. Several previous studies indicated that the patients with MAFLD had a higher prevalence of COVID-19 and a tendency to develop severe type of respiratory infection, and others indicated that liver injury would be exacerbated in the patients with MAFLD once infected with COVID-19. The mechanism underlying the relationship between MAFLD and COVID-19 infection has not been thoroughly investigated, and recent studies indicated that multifactorial mechanisms, such as altered host angiotensin converting enzyme 2 (ACE2) receptor expression, direct viral attack, disruption of cholangiocyte function, systemic inflammatory reaction, drug-induced liver injury, hepatic ischemic and hypoxic injury, and MAFLD-related glucose and lipid metabolic disorders, might jointly contribute to both of the adverse hepatic and respiratory outcomes. In this review, we discussed the relationship between MAFLD and COVID-19 based on current available literature, and summarized the recommendations for clinical management of MAFLD patients during the pandemic of COVID-19. Highlights: • MAFLD was associated with increased risk and severity of COVID-19. • 31% of COVID-19 patients had MAFLD. • COVID-19 promoted liver injury and progression of MAFLD, especially in the youth. • The mechanism of liver injury in patients with COVID-19 was multifactorial. •Early screen and active treatment of MAFLD is recommended for patients with COVID-19. [ABSTRACT FROM AUTHOR]

Background: The performance of liver stiffness measurements (LSMs) obtained using FibroScan can be affected by several factors, and cut-off values are different for fibrosis caused by various aetiologies. The study aims to evaluate the diagnostic accuracy of LSM in nonalcoholic fatty liver disease (NAFLD) patients with abnormal glucose metabolism and investigate whether the LSM value would be affected by metabolic indicators. Methods: The study involved 91 NAFLD patients with abnormal glucose metabolism who underwent liver biopsy. The diagnostic accuracy of LSM value was evaluated by the receiver operator characteristic (ROC) curves, with the biopsy results taken as the gold standard. Multivariate linear regression and subgroup analysis were performed to determine the correlated indicators. Results: The areas under the ROC curves (AUROCs) of LSM values for detecting fibrosis stage ≥1, 2, 3 and 4 were 0.793 (95% confidence interval [CI]: 0.695–0.871), 0.764 (95% CI: 0.663–0.846), 0.837 (95% CI: 0.744–0.906) and 0.902 (95% CI: 0.822–0.955), with cut-off values of 6.3, 7.6, 8.3 and 13.8 kPa, respectively. Multivariate linear regression demonstrated that haemoglobin A1c (HbA1c, β = 0.205, P = 0.026) and alanine aminotransferase (ALT, β = 0.192, P = 0.047) were independently associated with the LSM value after adjustment for fibrosis stage, ballooning and inflammation grade from liver biopsy. Subgroup analysis demonstrated that LSM values were slightly higher in patients with HbA1c ≥7% than in those with HbA1c < 7% and in patients with body mass index (BMI) ≥30 kg/m2 than in those with BMI < 30 kg/m2. Conclusions: FibroScan was valuable for the evaluation of liver fibrosis in NAFLD patients with abnormal glucose metabolism. FibroScan is recommended to evaluate severe fibrosis, especially to exclude advanced fibrosis. Glucose metabolism state may affect LSM values. [ABSTRACT FROM AUTHOR]

Background: Excessive intrahepatic lipid accumulation is the major characteristic of nonalcoholic fatty liver disease (NAFLD). We sought to identify the mechanisms involved in hepatic triglyceride (TG) homeostasis. Forkhead box class O (FoxO) transcription factors have been shown to play an important role in hepatic metabolism. However, little is known about the effect of FoxO3 on hepatic TG metabolism. Methods: Liver biopsy samples from patients with NALFD and liver tissues from high glucose and high sucrose (HFHS) fed mice, ob/ob mice and db/db mice were collected for protein and mRNA analysis. HepG2 cells were transfected with small interfering RNA to mediate FoxO3 knockdown, or adenovirus and plasmid to mediate FoxO3 overexpression. FoxO3-cDNA was delivered by adenovirus to the liver of C57BL/6 J male mice on a chow diet or on a high-fat diet, followed by determination of hepatic lipid metabolism. Sterol regulatory element-binding protein 1c (SREBP1c) luciferase reporter gene plasmid was co-transfected into HepG2 cells with FoxO3 overexpression plasmid. Results: FoxO3 expression was increased in the livers of HFHS mice, ob/ob mice, db/db mice and patients with NAFLD. Knockdown of FoxO3 reduced whereas overexpression of FoxO3 increased cellular TG concentrations in HepG2 cells. FoxO3 gain-of-function caused hepatic TG deposition in C57BL/6 J mice on a chow diet and aggravated hepatic steatosis when fed a high-fat diet. Analysis of the transcripts established the increased expression of genes related to TG synthesis, including SREBP1c, SCD1, FAS, ACC1, GPAM and DGAT2 in mouse liver. Mechanistically, overexpression of FoxO3 stimulated the expression of SREBP1c, whereas knockdown of FoxO3 inhibited the expression of SREBP1c. Luciferase reporter assays showed that SREBP1c regulated the transcriptional activity of the SREBP1c promoter. Conclusions: FoxO3 promotes the transcriptional activity of the SREBP1c promoter, thus leading to increased TG synthesis and hepatic TG accumulation. [ABSTRACT FROM AUTHOR]

Background: The prevalence of nonalcoholic fatty liver disease (NAFLD) has increased worldwide. Metformin decreases triglyceride (TG) accumulation in hepatocytes in vivo and in vitro. Stearyl-coenzyme A desaturase 1 (SCD1) knockout mice also show decreased liver TG accumulation; however, whether SCD1 plays a role in the effect of metformin on TG accumulation is unknown. Therefore, the aim of this study was to investigate whether SCD1 mediated the effect of metformin on TG accumulation. Methods: HepG2 and AML12 cells were exposed to high glucose and high insulin with or without metformin. An adenovirus was used for the SCD1 knockdown and overexpression. The triglyceride level in cells was detected. The expression of related genes was detected by Western blot and quantitative real-time PCR. A dual-luciferase reporter assay was used to determine the effect of metformin on the transcriptional activity of the SCD1 promoter. Results: Metformin decreased TG accumulation to normal level in HepG2 cells exposed to high glucose and high insulin. The expression of SCD1 and fatty acid synthetase (FAS) was also decreased to normal level by metformin. Knockdown of SCD1 mimicked the effect of metformin on decreasing TG levels in AML12 cells, and the overexpression of SCD1 attenuated the effect of metformin on decreasing TG accumulation in HepG2 cells. The dual-luciferase reporter assay showed that the transcriptional activity of the SCD1 promoter (− 550/+ 199) after metformin treatment was 2-fold lower compared to control group in HepG2 cells. Additionally, the phosphorylation of AMPK after metformin treatment was 2-fold higher, and the expression of sterol regulatory element-binding protein-1c (SREBP-1c) after metformin treatment was about 2-fold lower compared to high glucose and high insulin group in HepG2 cells. Conclusions: Together, these results reveal that metformin reduces TG accumulation in HepG2 cells via inhibiting the expression of SCD1. [ABSTRACT FROM AUTHOR]