scholarly journals Role of FXR in Bile Acid and Metabolic Homeostasis in NASH: Pathogenetic Concepts and Therapeutic Opportunities

Author(s):  
Richard Radun ◽  
Michael Trauner

AbstractNonalcoholic fatty liver disease (NAFLD) has become the most prevalent cause of liver disease, increasingly contributing to the burden of liver transplantation. In search for effective treatments, novel strategies addressing metabolic dysregulation, inflammation, and fibrosis are continuously emerging. Disturbed bile acid (BA) homeostasis and microcholestasis via hepatocellular retention of potentially toxic BAs may be an underappreciated factor in the pathogenesis of NAFLD and nonalcoholic steatohepatitis (NASH) as its progressive variant. In addition to their detergent properties, BAs act as signaling molecules regulating cellular homeostasis through interaction with BA receptors such as the Farnesoid X receptor (FXR). Apart from being a key regulator of BA metabolism and enterohepatic circulation, FXR regulates metabolic homeostasis and has immune-modulatory effects, making it an attractive therapeutic target in NAFLD/NASH. In this review, the molecular basis and therapeutic potential of targeting FXR with a specific focus on restoring BA and metabolic homeostasis in NASH is summarized.

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Caihua Wang ◽  
Chunpeng Zhu ◽  
Liming Shao ◽  
Jun Ye ◽  
Yimin Shen ◽  
...  

Nonalcoholic fatty liver disease (NAFLD) is a major health threat around the world and is characterized by dysbiosis. Primary bile acids are synthesized in the liver and converted into secondary bile acids by gut microbiota. Recent studies support the role of bile acids in modulating dysbiosis and NAFLD, while the mechanisms are not well elucidated. Dysbiosis may alter the size and the composition of the bile acid pool, resulting in reduced signaling of bile acid receptors such as farnesoid X receptor (FXR) and Takeda G protein-coupled receptor 5 (TGR5). These receptors are essential in lipid and glucose metabolism, and impaired bile acid signaling may cause NAFLD. Bile acids also reciprocally regulate the gut microbiota directly via antibacterial activity and indirectly via FXR. Therefore, bile acid signaling is closely linked to dysbiosis and NAFLD. During the past decade, stimulation of bile acid receptors with their agonists has been extensively explored for the treatment of NAFLD in both animal models and clinical trials. Early evidence has suggested the potential of bile acid receptor agonists in NAFLD management, but their long-term safety and effectiveness need further clarification.


2018 ◽  
Vol 315 (5) ◽  
pp. G772-G780 ◽  
Author(s):  
Lino Arisqueta ◽  
Hiart Navarro-Imaz ◽  
Ibone Labiano ◽  
Yuri Rueda ◽  
Olatz Fresnedo

High-fat diet (HFD) feeding or leptin-deficient mice are extensively used as models resembling features of human nonalcoholic fatty liver disease (NAFLD). The concurrence of experimental factors as fat content and source or total caloric intake leads to prominent differences in the development of the hepatic steatosis and related disturbances. In this work, we characterized the hepatic lipid accumulation induced by HFD in wild-type (WT) and ob/ ob mice with the purpose of differentiating adaptations to HFD from those specific of increased overfeeding due to leptin deficiency-associated hyperphagia. Given that most published works have been done in male models, we used female mice with the aim of increasing the body of evidence regarding NAFLD in female subjects. HFD promoted liver lipid accumulation only in the hyperphagic strain. Nevertheless, a decrease of lipid droplet-associated cholesteryl ester (CE) in both WT and obese animals was observed. These changes were accompanied by an improvement in the profile of lipoproteins that transport cholesterol and liver function markers in plasma from ob/ ob mice and a lower hepatic index. Using primary hepatocytes from female mice, overaccumulation of CE induced by 0.4 mM oleic acid reversed in the presence of a specific Takeda G protein-coupled bile acid receptor agonist. Nevertheless, hepatocytes from male mice were not responsive. This study suggests that enterohepatic circulation of bile acids might be one of the factors that can affect sex dimorphism in NAFLD development, which underlines the importance of including female models in the NAFLD research field. NEW & NOTEWORTHY This work provides new insight into the use of high-fat diet as a model to induce nonalcoholic fatty liver disease in wild-type and ob/ ob female mice. We show that high-fat diet induces steatosis only in ob/ ob mice while, surprisingly, several health indicators improve. Noteworthy, experiments with primary hepatocytes from male and female mice show that they express Takeda G protein-coupled bile acid receptor and that it and bile acid enterohepatic circulation might be accountable for sex dimorphism in nonalcoholic fatty liver disease development.


2021 ◽  
Vol 12 ◽  
Author(s):  
Wen-wen Zhao ◽  
Meng Xiao ◽  
Xia Wu ◽  
Xiu-wei Li ◽  
Xiao-xi Li ◽  
...  

Bile acid (BA) metabolism is an attractive therapeutic target in nonalcoholic fatty liver disease (NAFLD). We aimed to investigate the effect of ilexsaponin A1 (IsA), a major bioactive ingredient of Ilex, on high-fat diet (HFD)-induced NAFLD in mice with a focus on BA homeostasis. Male C57BL/6J mice were fed an HFD to induce NAFLD and were treated with IsA (120 mg/kg) for 8 weeks. The results showed that administration of IsA significantly decreased serum total cholesterol (TC), attenuated liver steatosis, and decreased total hepatic BA levels in HFD-induced NAFLD mice. IsA-treated mice showed increased BA synthesis in the alternative pathway by upregulating the gene expression levels of sterol 27-hydroxylase (CYP27A1) and cholesterol 7b-hydroxylase (CYP7B1). IsA treatment accelerated efflux and decreased uptake of BA in liver by increasing hepatic farnesoid X receptor (FXR) and bile salt export pump (BSEP) expression, and reducing Na+-taurocholic acid cotransporting polypeptide (NTCP) expression. Alterations in the gut microbiota and increased bile salt hydrolase (BSH) activity might be related to enhanced fecal BA excretion in IsA-treated mice. This study demonstrates that consumption of IsA may prevent HFD-induced NAFLD and exert cholesterol-lowering effects, possibly by regulating the gut microbiota and BA metabolism.


2018 ◽  
Vol 20 (6) ◽  
pp. 449-453
Author(s):  
Apollinariya V. Bogolyubova ◽  
Alexander Y. Mayorov ◽  
Ekaterina E. Mishina ◽  
Anton M. Schwartz ◽  
Pavel V. Belousov

Nonalcoholic fatty liver disease (NAFLD) is a group of obesity-associated pathological changes characterized by abnormal accumulation of lipids in cells of the liver parenchyma. NAFLD and associated conditions, namely insulin resistance and type II diabetes mellitus (DM2), as well as the possible risks of developing fibrosis and cirrhosis with a potential outcome in hepatocellular carcinoma, represent the primary health problems in developed countries, gradually replacing the importance of similar pathologies caused by the regular use of hepatotoxic doses of alcoholic beverages. Recent fundamental and clinical studies demonstrated the important role of the farnesoid receptor (FXR, NR1H4) in the regulation of the metabolism of glucose, lipids and bile acids. This review focuses on the molecular aspects of the pathogenesis of NAFLD, the role of FXR (NR1H4) in the biology of this disease, and the prospects for using different FXR (NR1H4) modulators for therapy of NAFLD and associated conditions such as metabolic syndrome and DM2, as well as a number of other FXR (NR1H4) mediated diseases.


2020 ◽  
Vol 26 (32) ◽  
pp. 3915-3927 ◽  
Author(s):  
Stefano Ballestri ◽  
Claudio Tana ◽  
Maria Di Girolamo ◽  
Maria Cristina Fontana ◽  
Mariano Capitelli ◽  
...  

: Nonalcoholic fatty liver disease (NAFLD) embraces histopathological entities ranging from the relatively benign simple steatosis to the progressive form nonalcoholic steatohepatitis (NASH), which is associated with fibrosis and an increased risk of progression to cirrhosis and hepatocellular carcinoma. NAFLD is the most common liver disease and is associated with extrahepatic comorbidities including a major cardiovascular disease burden. : The non-invasive diagnosis of NAFLD and the identification of subjects at risk of progressive liver disease and cardio-metabolic complications are key in implementing personalized treatment schedules and follow-up strategies. : In this review, we highlight the potential role of ultrasound semiquantitative scores for detecting and assessing steatosis severity, progression of NAFLD, and cardio-metabolic risk. : Ultrasonographic scores of fatty liver severity act as sensors of cardio-metabolic health and may assist in selecting patients to submit to second-line non-invasive imaging techniques and/or liver biopsy.


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