Abstract 5521: Activation of Farnesoid X Receptor (FXR) Reduces Atherosclerosis in LDLRKO and apoEKO Mice

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Helen B Hartman ◽  
Douglas C Harnish ◽  
Mark J Evans
Keyword(s):  
Bile Acid ◽  
Ldl Cholesterol ◽  
Atherosclerotic Lesion ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Western Diet ◽  
Cholesterol Homeostasis ◽  
Farnesoid X Receptor ◽  
Protective Mechanism ◽  
Lesion Development

The nuclear hormone receptors farnesoid X Receptor (FXR) and small heterodimer partner (SHP) regulate bile acid synthesis and cholesterol homeostasis in a complex fashion. In regard to atherosclerosis, FXR repression of bile acid synthesis has been proposed to be either detrimental due to reduced elimination of cholesterol or beneficial due to decreased cholesterol absorption. FXRKO mice have failed to resolved this question, with atherosclerotic lesions in FXRKO mice either enhanced (apoE, FXRdKO mice) or reduced (LDLR, FXRdKO mice). Here we demonstrate that the synthetic ligand FXR-450 blocked Western diet-mediated increases in VLDL and LDL cholesterol in both male or female LDLRKO and male or female apoEKO mice. Correspondingly, FXR-450 strongly reduced lesion development in female and male ApoEKO mice fed a Western diet. To determine if FXR-450 reduction of lipids and atherosclerotic lesion size is solely mediated by induction of SHP and repression of bile acid synthesis, LDLRKO/SHPKO and ApoEKO/SHPKO were similarly analyzed. In female LDLRKO/SHPKO or female apoEKO/SHPKO, FXR-450 no longer reduced VLDL or LDL cholesterol. Surprisingly, FXR-450 still reduced VLDL and LDL cholesterol in male LDLRKO/SHPKO and male apoEKO/SHPKO. Further FXR-450 significantly reduced lesion development in male apoEKO/SHPKO mice. These results demonstrate activation of FXR has highly beneficial effects on plasma lipids and lesion formation in multiple mouse atherosclerosis models. Further, while induction of SHP appears to be the predominant protective mechanism of FXR activation in female mice, additional mechanisms may play a role, particularly in male mice.

scholarly journals Endogenous Estrogens Lower Plasma PCSK9 and LDL Cholesterol But Not Lp(a) or Bile Acid Synthesis in Women

2012 ◽  
Vol 32 (3) ◽  
pp. 810-814 ◽  
Author(s):  
Lena Persson ◽  
Peter Henriksson ◽  
Eli Westerlund ◽  
Outi Hovatta ◽  
Bo Angelin ◽  
...  
Keyword(s):  
Bile Acid ◽  
Ldl Cholesterol ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Lower Plasma

scholarly journals Farnesoid X receptor induces Takeda G-protein receptor 5 cross-talk to regulate bile acid synthesis and hepatic metabolism

2017 ◽  
Vol 292 (26) ◽  
pp. 11055-11069 ◽  
Author(s):  
Preeti Pathak ◽  
Hailiang Liu ◽  
Shannon Boehme ◽  
Cen Xie ◽  
Kristopher W. Krausz ◽  
...  
Keyword(s):  
Bile Acid ◽  
G Protein ◽  
Cross Talk ◽  
Hepatic Metabolism ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Farnesoid X Receptor ◽  
Protein Receptor

scholarly journals Regulation of Bile Acid and Cholesterol Metabolism by PPARs

PPAR Research ◽  
2009 ◽  
Vol 2009 ◽  
pp. 1-15 ◽  
Author(s):  
Tiangang Li ◽  
John Y. L. Chiang
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Cholesterol Metabolism ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Cholesterol Homeostasis ◽  
Acid Oxidation ◽  
Peroxisome Proliferator ◽  
Major Pathway ◽  
Therapeutic Implications

Bile acids are amphipathic molecules synthesized from cholesterol in the liver. Bile acid synthesis is a major pathway for hepatic cholesterol catabolism. Bile acid synthesis generates bile flow which is important for biliary secretion of free cholesterol, endogenous metabolites, and xenobiotics. Bile acids are biological detergents that facilitate intestinal absorption of lipids and fat-soluble vitamins. Recent studies suggest that bile acids are important metabolic regulators of lipid, glucose, and energy homeostasis. Agonists of peroxisome proliferator-activated receptors (PPARα, PPARγ, PPARδ) regulate lipoprotein metabolism, fatty acid oxidation, glucose homeostasis and inflammation, and therefore are used as anti-diabetic drugs for treatment of dyslipidemia and insulin insistence. Recent studies have shown that activation of PPARαalters bile acid synthesis, conjugation, and transport, and also cholesterol synthesis, absorption and reverse cholesterol transport. This review will focus on the roles of PPARs in the regulation of pathways in bile acid and cholesterol homeostasis, and the therapeutic implications of using PPAR agonists for the treatment of metabolic syndrome.

scholarly journals Recent advances in understanding bile acid homeostasis

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 2029 ◽  
Author(s):  
John YL Chiang
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Farnesoid X Receptor ◽  
Recent Advances ◽  
Bile Acid Pool Size ◽  
Bile Acid Receptor ◽  
Acid Toxicity ◽  
G Protein Coupled

Bile acids are derived from cholesterol to facilitate intestinal nutrient absorption and biliary secretion of cholesterol. Recent studies have identified bile acids as signaling molecules that activate nuclear farnesoid X receptor (FXR) and membrane G protein-coupled bile acid receptor-1 (Gpbar-1, also known as TGR5) to maintain metabolic homeostasis and protect liver and other tissues and cells from bile acid toxicity. Bile acid homeostasis is regulated by a complex mechanism of feedback and feedforward regulation that is not completely understood. This review will cover recent advances in bile acid signaling and emerging concepts about the classic and alternative bile acid synthesis pathway, bile acid composition and bile acid pool size, and intestinal bile acid signaling and gut microbiome in regulation of bile acid homeostasis.

scholarly journals Bile acid diarrhoea: pathophysiology, diagnosis and management

2020 ◽  
pp. flgastro-2020-101436
Author(s):  
Alexia Farrugia ◽  
Ramesh Arasaradnam
Keyword(s):  
Bile Acid ◽  
Enterohepatic Circulation ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Feedback Loops ◽  
Farnesoid X Receptor ◽  
Delay In Diagnosis ◽  
Negative Feedback Loops ◽  
Irritable Bowel ◽  
Fibroblast Growth Factor 19

The actual incidence of bile acid diarrhoea (BAD) is unknown, however, there is increasing evidence that it is misdiagnosed in up to 30% with diarrhoea-predominant patients with irritable bowel syndrome. Besides this, it may also occur following cholecystectomy, infectious diarrhoea and pelvic chemoradiotherapy.BAD may result from either hepatic overproduction of bile acids or their malabsorption in the terminal ileum. It can result in symptoms such as bowel frequency, urgency, nocturnal defecation, excessive flatulence, abdominal pain and incontinence of stool. Bile acid synthesis is regulated by negative feedback loops related to the enterohepatic circulation, which are dependent on the farnesoid X receptor and fibroblast growth factor 19. Interruption of these feedback loops is thought to cause bile acid overproduction leading to BAD. This process may occur idiopathically or following a specific trigger such as cholecystectomy. There may also be an interplay with the gut microbiota, which has been reported to be significantly different in patients with severe BAD.Patients with suspected BAD are investigated in various ways including radionucleotide imaging such as SeHCAT scans (though this is not available worldwide) and blood tests. However, other methods such as bile acid measurement in stool (either spot test or 48 hours samples) and urine tests have been explored. Importantly, delay in diagnosis and treatment of BAD greatly affects patient’s quality of life and may double the overall cost of diagnosis.

scholarly journals Mechanism of tissue-specific farnesoid X receptor in suppressing the expression of genes in bile-acid synthesis in mice

Hepatology ◽  
2012 ◽  
Vol 56 (3) ◽  
pp. 1034-1043 ◽  
Author(s):  
Bo Kong ◽  
Li Wang ◽  
John Y.L. Chiang ◽  
Youcai Zhang ◽  
Curtis D. Klaassen ◽  
...  
Keyword(s):  
Bile Acid ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Farnesoid X Receptor ◽  
Tissue Specific ◽  
Expression Of Genes

scholarly journals The influence of biological sex and sex hormones on bile acid synthesis and cholesterol homeostasis

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Taylor Phelps ◽  
Erin Snyder ◽  
Erin Rodriguez ◽  
Hailey Child ◽  
Pamela Harvey
Keyword(s):  
Bile Acid ◽  
Therapeutic Potential ◽  
Cholesterol Biosynthesis ◽  
Elevated Serum ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Cholesterol Homeostasis ◽  
Cholesterol Lowering ◽  
Promising Alternative ◽  
Biological Sex

AbstractObesity and elevated serum lipids are associated with a threefold increase in the risk of developing atherosclerosis, a condition that underlies stroke, myocardial infarction, and sudden cardiac death. Strategies that aim to reduce serum cholesterol through modulation of liver enzymes have been successful in decreasing the risk of developing atherosclerosis and reducing mortality. Statins, which inhibit cholesterol biosynthesis in the liver, are considered among the most successful compounds developed for the treatment of cardiovascular disease. However, recent debate surrounding their effectiveness and safety prompts consideration of alternative cholesterol-lowering therapies, including increasing cholesterol catabolism through bile acid (BA) synthesis. Targeting the enzymes that convert cholesterol to BAs represents a promising alternative to other cholesterol-lowering approaches that treat atherosclerosis as well as fatty liver diseases and diabetes mellitus. Compounds that modify the activity of these pathways have been developed; however, there remains a lack of consideration of biological sex. This is necessary in light of strong evidence for sexual dimorphisms not only in the incidence and progression of the diseases they influence but also in the expression and activity of the proteins affected and in the manner in which men and women respond to drugs that modify lipid handling in the liver. A thorough understanding of the enzymes involved in cholesterol catabolism and modulation by biological sex is necessary to maximize their therapeutic potential.

Knockdown of ATP8B1 expression leads to specific downregulation of the bile acid sensor FXR in HepG2 cells: effect of the FXR agonist GW4064

2009 ◽  
Vol 296 (5) ◽  
pp. G1119-G1129 ◽  
Author(s):  
Pilar Martínez-Fernández ◽  
Loreto Hierro ◽  
Paloma Jara ◽  
Luis Alvarez
Keyword(s):  
Bile Acid ◽  
Hepg2 Cells ◽  
Target Genes ◽  
Constitutive Androstane Receptor ◽  
Pregnane X Receptor ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Bile Secretion ◽  
Farnesoid X Receptor ◽  
Mrna Levels

Farnesoid X receptor (FXR) is a bile acid-sensing nuclear receptor that controls bile acid homeostasis. It has been suggested that downregulation of FXR contributes to the pathogenesis of an inherited disorder of bile secretion caused by mutations in ATP8B1. We have investigated the relationship between ATP8B1 knockdown and FXR downregulation in the human hepatoblastoma cell line HepG2. Transfection of HepG2 cells with ATP8B1 small interfering RNA (siRNA) duplexes led to a 60% reduction in the endogenous levels of ATP8B1 mRNA and protein and a concomitant decrease in FXR mRNA and protein content, as well as in FXR phosphorylation. This decrease was accompanied by a marked reduction in mRNA levels of a subset of FXR targets, such as bile salt export pump ( ABCB11), small heterodimer partner, and uridine 5′-diphosphate-glucuronosyltransferase. ATP8B1 inhibition specifically targeted FXR since mRNA expression of other prominent nuclear receptors, such as pregnane X receptor and constitutive androstane receptor, or liver-enriched transcription factors, such as hepatocyte nuclear factor 1α ( HNF-1α) and HNF-4α, was not altered. The expression of other key genes involved in bile acid synthesis, detoxification, and transport also remained unchanged upon ATP8B1 knockdown. Supporting the specificity of the effect, siRNA-mediated silencing of ABCB11, whose defect is associated with another inherited disorder of bile secretion, did not affect FXR expression. Treatment with the synthetic FXR agonist GW4064 was able to partially neutralize ATP8B1 siRNA-mediated FXR downregulation and fully counteract inhibition of FXR target genes. Collectively these findings indicate that ATP8B1 knockdown specifically downregulates FXR, and this action can be circumvented by treatment with FXR agonists.

scholarly journals Effects of long-term plant sterol or stanol ester consumption on lipid and lipoprotein metabolism in subjects on statin treatment

2008 ◽  
Vol 100 (5) ◽  
pp. 937-941 ◽  
Author(s):  
Ariënne de Jong ◽  
Jogchum Plat ◽  
Dieter Lütjohann ◽  
Ronald P. Mensink
Keyword(s):  
Bile Acid ◽  
Plant Sterol ◽  
Ldl Cholesterol ◽  
Cholesterol Metabolism ◽  
Acid Synthesis ◽  
Statin Treatment ◽  
Bile Acid Synthesis ◽  
Control Group ◽  
Stanol Ester

Consumption of plant sterol- or stanol-enriched margarines by statin users results in an additional LDL-cholesterol reduction of approximately 10 %, which may be larger than the average decrease of 3–7 % achieved by doubling the statin dose. However, whether this effect persists in the long term is not known. Therefore, we examined in patients already on stable statin treatment the effects of 85 weeks of plant sterol and stanol ester consumption on the serum lipoprotein profile, cholesterol metabolism, and bile acid synthesis. For this, a double-blind randomised trial was designed in which fifty-four patients consumed a control margarine with no added plant sterols or stanols for 5 weeks (run-in period). For the next 85 weeks, seventeen subjects continued with the control margarine and the other two groups with either a plant sterol (n18) or plant stanol (n19) (2·5 g/d each) ester-enriched margarine. Blood was sampled at the end of the run-in period and every 20 weeks during the intervention period. Compared with the control group, plant sterol and stanol ester consumption reduced LDL-cholesterol by 0·28 mmol/l (or 8·7 %;P = 0·08) and 0·42 mmol/l (13·1 %;P = 0·006) respectively after 85 weeks. No effects were found on plasma concentrations of oxysterols or 7α-hydroxy-4-cholesten-3-one, a bile acid synthesis marker. We conclude that long-term consumption of both plant sterol and stanol esters effectively lowered LDL-cholesterol concentrations in statin users.

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