Bile Acids: The Good, the Bad, and the Ugly

Physiology ◽  
1999 ◽  
Vol 14 (1) ◽  
pp. 24-29 ◽  
Author(s):  
Alan F. Hofmann
Keyword(s):  
Bile Acids ◽  
Enterohepatic Circulation ◽  
Cholesterol Metabolism ◽  
Plasma Cholesterol ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Lipid Absorption ◽  
Bile Acid Metabolism ◽  
Cholesterol Levels ◽  
Density Lipoprotein Receptor

Bile acids, amphipathic end products of cholesterol metabolism, are “good” in the infant because they enhance lipid absorption and thereby promote growth. Bile acids also induce bile flow and biliary lipid secretion. The enterohepatic circulation of bile acids is “bad” in the adult because it downregulates hepatocyte low-density lipoprotein receptor activity and thereby elevates plasma cholesterol levels. Defects in bile acid metabolism such as impaired biosynthesis or transport are “ugly” because they cause morbidity and death. New approaches for treating these defects are being developed.

scholarly journals Two Weeks Of Western Diet Disrupts Liver Molecular Markers Of Cholesterol Metabolism In Rat

2020 ◽  
Author(s):  
Roxane St-Amand ◽  
Emilienne T. Ngo Sock ◽  
Samantha Quinn ◽  
Jean-Marc Lavoie ◽  
David H. St-Pierre
Keyword(s):  
Total Cholesterol ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Plasma Total Cholesterol ◽  
Cholesterol Levels ◽  
Density Lipoprotein Receptor ◽  
Element Binding Protein

Abstract Background: The present study was designed to test the hypothesis that in the liver, excessive fat accumulation impairs cholesterol metabolism mainly by altering the low-density lipoprotein-receptor (LDL-R) pathway. Method: Young male Wistar rats were fed standard (SD), high fat (HFD; 60% kcal) or Western (WD; 40% fat + 35% sucrose (17.5% fructose)) diets for 2 or 6 weeks. Results: Weight gain (~ 40g) was observed only following 6 weeks of the obesogenic diets (P < 0.01). Compared to the 2-week treatment, obesogenic diets tripled fat pad weight (~ 20 vs 7 g) after 6 weeks. Hepatic triglyceride (TG) levels were greater in response to both the WD and HFD compared to the SD (P < 0.01) at 2 and 6 weeks and their concentrations were greater (P < 0.05) in WD than HFD at 2 weeks. Plasma total cholesterol levels were higher (P < 0.05) in animals submitted to WD. After 2 and 6 weeks, liver expression of LDL-R, proprotein convertase subtilisin/kexin 9 (PCSKk9) and sterol regulatory element binding protein 2 (SREBP2), involved in LDL-cholesterol uptake, was lower in animals submitted to WD than in others treated with HFD or SD (P < 0.01). Similarly, low-density lipoprotein-receptor-related protein 1 (LRP1) and acyl-CoA cholesterol acyltransferase-2 (ACAT-2) mRNA levels were lower (P < 0.01) among WD compared to SD-fed rats. Expression of the gene coding the main regulator of endogenous cholesterol synthesis, 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCoAR) was reduced in response to WD compared to SD and HFD at 2 (P < 0.001) and 6 (P < 0.05) weeks. Being enriched in fructose, the WD strongly promoted the expression of carbohydrate-response element binding protein (ChREBP) and acetyl-CoA carboxylase (ACC), two key regulators of de novo lipogenesis. Conclusion: These results show that the WD promptly increased TG levels in the liver by potentiating fat storage. This impaired the pathway of hepatic cholesterol uptake via the LDL-R axis, promoting a rapid increase in plasma total cholesterol levels. These results indicate that liver fat content is a factor involved in the regulation of plasma cholesterol.

scholarly journals Two Weeks Of Western Diet Disrupts Liver Molecular Markers Of Cholesterol Metabolism In Rat

2020 ◽  
Author(s):  
Roxane St-Amand ◽  
Emilienne T. Ngo Sock ◽  
Samantha Quinn ◽  
Jean-Marc Lavoie ◽  
David H. St-Pierre
Keyword(s):  
Total Cholesterol ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Plasma Total Cholesterol ◽  
Cholesterol Levels ◽  
Density Lipoprotein Receptor ◽  
Element Binding Protein

Abstract Background: The present study was designed to test the hypothesis that in the liver, excessive fat accumulation impairs cholesterol metabolism mainly by altering the low-density lipoprotein-receptor (LDL-R) pathway. Method: Young male Wistar rats were fed standard (SD), high fat (HFD; 60% kcal) or Western (WD; 40% fat + 35% sucrose (17.5% fructose)) diets for 2 or 6 weeks. Results: Weight gain (~ 40g) was observed only following 6 weeks of the obesogenic diets (P < 0.01). Compared to the 2-week treatment, obesogenic diets tripled fat pad weight (~ 20 vs 7 g) after 6 weeks. Hepatic triglyceride (TG) levels were greater in response to both the WD and HFD compared to the SD (P < 0.01) at 2 and 6 weeks and their concentrations were greater (P < 0.05) in WD than HFD at 2 weeks. Plasma total cholesterol levels were higher (P < 0.05) in animals submitted to WD. After 2 and 6 weeks, liver expression of LDL-R, proprotein convertase subtilisin/kexin 9 (PCSKk9) and sterol regulatory element binding protein protein 2 (SREBP2), involved in LDL-cholesterol uptake, was lower in animals submitted to WD than in others treated with HFD or SD (P < 0.01). Similarly, low-density lipoprotein-receptor-related protein 1 (LRP1) and acyl-CoA cholesterol acyltransferase-2 (ACAT-2) mRNA levels were lower (P < 0.01) among WD compared to SD-fed rats. Expression of the gene coding the main regulator of endogenous cholesterol synthesis, 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCoAR) was reduced in response to WD compared to SD and HFD at 2 (P < 0.001) and 6 (P < 0.05) weeks. Being enriched in fructose, the WD strongly promoted the expression of carbohydrate-response element binding protein (ChREBP) and acetyl-CoA carboxylase (ACC), two key regulators of de novo lipogenesis. Conclusion: These results show that the WD promptly increased TG levels in the liver by potentiating fat storage. This impaired the pathway of hepatic cholesterol uptake via the LDL-R axis, promoting a rapid increase in plasma total cholesterol levels. These results indicate that liver fat content is a factor involved in the regulation of plasma cholesterol.

scholarly journals Two Weeks Of Western Diet Disrupts Liver Molecular Markers Of Cholesterol Metabolism In Rat

2020 ◽  
Author(s):  
Roxane St-Amand ◽  
Emilienne T. Ngo Sock ◽  
Samantha Quinn ◽  
Jean-Marc Lavoie ◽  
David H. St-Pierre
Keyword(s):  
Total Cholesterol ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Plasma Total Cholesterol ◽  
Cholesterol Levels ◽  
Density Lipoprotein Receptor ◽  
Element Binding Protein

Abstract Background: The present study was designed to test the hypothesis that in the liver, excessive fat accumulation impairs cholesterol metabolism mainly by altering the low-density lipoprotein-receptor (LDL-R) pathway. Method: Young male Wistar rats were fed standard (SD), high fat (HFD; 60% kcal) or Western (WD; 40% fat + 35% sucrose (17.5% fructose)) diets for 2 or 6 weeks. Results: Weight gain (~ 40g) was observed only following 6 weeks of the obesogenic diets (P < 0.01). Compared to the 2-week treatment, obesogenic diets tripled fat pad weight (~ 20 vs 7 g) after 6 weeks. Hepatic triglyceride (TG) levels were greater in response to both the WD and HFD compared to the SD (P < 0.01) at 2 and 6 weeks and their concentrations were greater (P < 0.05) in WD than HFD at 2 weeks. Plasma total cholesterol levels were higher (P < 0.05) in animals submitted to WD. After 2 and 6 weeks, liver expression of LDL-R, proprotein convertase subtilisin/kexin 9 (PCSKk9) and sterol regulatory element binding protein 2 (SREBP2), involved in LDL-cholesterol uptake, was lower in animals submitted to WD than in others treated with HFD or SD (P < 0.01). Similarly, low-density lipoprotein-receptor-related protein 1 (LRP1) and acyl-CoA cholesterol acyltransferase-2 (ACAT-2) mRNA levels were lower (P < 0.01) among WD compared to SD-fed rats. Expression of the gene coding the main regulator of endogenous cholesterol synthesis, 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCoAR) was reduced in response to WD compared to SD and HFD at 2 (P < 0.001) and 6 (P < 0.05) weeks. Being enriched in fructose, the WD strongly promoted the expression of carbohydrate-response element binding protein (ChREBP) and acetyl-CoA carboxylase (ACC), two key regulators of de novo lipogenesis. Conclusion: These results show that the WD promptly increased TG levels in the liver by potentiating fat storage. This impaired the pathway of hepatic cholesterol uptake via the LDL-R axis, promoting a rapid increase in plasma total cholesterol levels. These results indicate that liver fat content is a factor involved in the regulation of plasma cholesterol.

scholarly journals Lactobacillus delbrueckii Interfere With Bile Acid Enterohepatic Circulation to Regulate Cholesterol Metabolism of Growing–Finishing Pigs via Its Bile Salt Hydrolase Activity

2020 ◽  
Vol 7 ◽  
Author(s):  
Gaifeng Hou ◽  
Wei Peng ◽  
Liangkai Wei ◽  
Rui Li ◽  
Yong Yuan ◽  
...  
Keyword(s):  
Bile Acid ◽  
Enterohepatic Circulation ◽  
Cholesterol Metabolism ◽  
Binding Protein ◽  
Density Lipoprotein ◽  
Lactobacillus Delbrueckii ◽  
Farnesoid X Receptor ◽  
Bile Salt Hydrolase ◽  
Lipoprotein Receptor ◽  
Density Lipoprotein Receptor

Microbiota-targeted therapies for hypercholesterolemia get more and more attention and are recognized as an effective strategy for preventing and treating cardiovascular disease. The experiment was conducted to investigate the cholesterol-lowering mechanism of Lactobacillus delbrueckii in a pig model. Twelve barrows (38.70 ± 5.33 kg) were randomly allocated to two groups and fed corn–soybean meal diets with either 0% (Con) or 0.1% Lactobacillus delbrueckii (Con + LD) for 28 days. L. delbrueckii–fed pigs had lower serum contents of total cholesterol (TC), total bile acids (TBAs), and triglyceride, but higher fecal TC and TBA excretion. L. delbrueckii treatment increased ileal Lactobacillus abundance and bile acid (BA) deconjugation and affected serum and hepatic BA composition. Dietary L. delbrueckii downregulated the gene expression of ileal apical sodium-dependent bile acid transporter (ASBT) and ileal bile acid binding protein (IBABP), and hepatic farnesoid X receptor (FXR), fibroblast growth factor (FGF19), and small heterodimer partner (SHP), but upregulated hepatic high-density lipoprotein receptor (HDLR), low-density lipoprotein receptor (LDLR), sterol regulatory element binding protein-2 (SREBP-2), and cholesterol-7α hydroxylase (CYP7A1) expression. Our results provided in vivo evidence that L. delbrueckii promote ileal BA deconjugation with subsequent fecal TC and TBA extraction by modifying ileal microbiota composition and induce hepatic BA neosynthesis via regulating gut–liver FXR–FGF19 axis.

scholarly journals Macrophage LRP1 Promotes Diet-Induced Hepatic Inflammation and Metabolic Dysfunction by Modulating Wnt Signaling

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Dianaly T. Au ◽  
Mary Migliorini ◽  
Dudley K. Strickland ◽  
Selen C. Muratoglu
Keyword(s):  
Insulin Resistance ◽  
Wnt Signaling ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Lipoprotein Receptor ◽  
Hepatic Inflammation ◽  
Low Density Lipoprotein Receptor ◽  
Density Lipoprotein Receptor

Hepatic inflammation is associated with the development of insulin resistance, which can perpetuate the disease state and may increase the risk of metabolic syndrome and diabetes. Despite recent advances, mechanisms linking hepatic inflammation and insulin resistance are still unclear. The low-density lipoprotein receptor-related protein 1 (LRP1) is a large endocytic and signaling receptor that is highly expressed in macrophages, adipocytes, hepatocytes, and vascular smooth muscle cells. To investigate the potential role of macrophage LRP1 in hepatic inflammation and insulin resistance, we conducted experiments using macrophage-specific LRP1-deficient mice (macLRP1−/−) generated on a low-density lipoprotein receptor knockout (LDLR−/−) background and fed a Western diet. LDLR−/−; macLRP1−/− mice gained less body weight and had improved glucose tolerance compared to LDLR−/− mice. Livers from LDLR−/−; macLRP1−/− mice displayed lower levels of gene expression for several inflammatory cytokines, including Ccl3, Ccl4, Ccl8, Ccr1, Ccr2, Cxcl9, and Tnf, and reduced phosphorylation of GSK3α and p38 MAPK proteins. Furthermore, LRP1-deficient peritoneal macrophages displayed altered cholesterol metabolism. Finally, circulating levels of sFRP-5, a potent anti-inflammatory adipokine that functions as a decoy receptor for Wnt5a, were elevated in LDLR−/−; macLRP1−/− mice. Surface plasmon resonance experiments revealed that sFRP-5 is a novel high affinity ligand for LRP1, revealing that LRP1 regulates levels of this inhibitor of Wnt5a-mediated signaling. Collectively, our results suggest that LRP1 expression in macrophages promotes hepatic inflammation and the development of glucose intolerance and insulin resistance by modulating Wnt signaling.

Lactobacillus reuteri A9 and Lactobacillus mucosae A13 isolated from Chinese superlongevity people modulate lipid metabolism in a hypercholesterolemia rat model

2019 ◽  
Vol 366 (24) ◽  
Author(s):  
Jinchi Jiang ◽  
Ninghan Feng ◽  
Chengcheng Zhang ◽  
Fengping Liu ◽  
Jianxin Zhao ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Mrna Expression ◽  
Lactobacillus Reuteri ◽  
Cholesterol Metabolism ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Bile Salt Hydrolase ◽  
Low Density ◽  
Cholesterol Levels ◽  
Lactobacillus Mucosae

ABSTRACT While there is strong evidence showing that many food-borne probiotics regulate cholesterol metabolism, few studies have examined how probiotics of human origin affect cholesterol metabolism. Because people living in so-called ‘longevity villages’ are unlikely to have hypercholesterolemia, we hypothesized that probiotics isolated from the residents would have cholesterol-reducing effects on rats with hypercholesterolemia. We isolated 16 strains of Lactobacillus from four longevity populations in China. The strains were tested in vitro for bile salt hydrolase (BSH) activity and two isolates, Lactobacillus reuteri A9 and Lactobacillus mucosae A13, were screened out. These two strains were then administered daily for 28 d to rats fed a cholesterol-rich diet. The serum total cholesterol levels in the L. reuteri A9 and L. mucosae A13 groups decreased by 24.3% and 21.6%, respectively. The serum low density lipoprotein cholesterol levels decreased by 23.8% and 25.2%, respectively. The L. reuteri A9 and L. mucosae A13 groups also exhibited upregulated hepatic mRNA expression of Sterol regulatory element-binding protein 2 (Srebp2) by 2.71-fold and 2.54-fold, respectively. The mRNA expression levels of hepatic low-density lipoprotein receptor (Ldlr) in the two groups were significantly up-regulated by 1.28-fold and 2.17-fold, respectively. The composition of gut microbiota was recovered by oral gavage in both experimental groups, and the destroyed diversity of gut microbiota was relieved.

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