scholarly journals Biogeography of microbial bile acid transformations along the murine gut

2020 ◽  
Vol 61 (11) ◽  
pp. 1450-1463 ◽  
Author(s):  
Solenne Marion ◽  
Lyne Desharnais ◽  
Nicolas Studer ◽  
Yuan Dong ◽  
Matheus D. Notter ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Bile Acid Pool Size ◽  
Host Signaling ◽  
Gut Microorganisms ◽  
Gut Microbial Community

Bile acids, which are synthesized from cholesterol by the liver, are chemically transformed along the intestinal tract by the gut microbiota, and the products of these transformations signal through host receptors, affecting overall host health. These transformations include bile acid deconjugation, oxidation, and 7α-dehydroxylation. An understanding of the biogeography of bile acid transformations in the gut is critical because deconjugation is a prerequisite for 7α-dehydroxylation and because most gut microorganisms harbor bile acid transformation capacity. Here, we used a coupled metabolomic and metaproteomic approach to probe in vivo activity of the gut microbial community in a gnotobiotic mouse model. Results revealed the involvement of Clostridium scindens in 7α-dehydroxylation, of the genera Muribaculum and Bacteroides in deconjugation, and of six additional organisms in oxidation (the genera Clostridium, Muribaculum, Bacteroides, Bifidobacterium, Acutalibacter, and Akkermansia). Furthermore, the bile acid profile in mice with a more complex microbiota, a dysbiosed microbiota, or no microbiota was considered. For instance, conventional mice harbor a large diversity of bile acids, but treatment with an antibiotic such as clindamycin results in the complete inhibition of 7α-dehydroxylation, underscoring the strong inhibition of organisms that are capable of carrying out this process by this compound. Finally, a comparison of the hepatic bile acid pool size as a function of microbiota revealed that a reduced microbiota affects host signaling but not necessarily bile acid synthesis. In this study, bile acid transformations were mapped to the associated active microorganisms, offering a systematic characterization of the relationship between microbiota and bile acid composition.

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.

Alteration of the enterohepatic recirculation of bile acids in rats after exposure to ionizing radiation

2004 ◽  
Vol 82 (2) ◽  
pp. 114-124 ◽  
Author(s):  
P Scanff ◽  
M Souidi ◽  
S Grison ◽  
N M Griffiths ◽  
P Gourmelon
Keyword(s):  
Bile Acid ◽  
Intestinal Absorption ◽  
Bile Acids ◽  
Ex Vivo ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Enterohepatic Recirculation ◽  
Enterohepatic Recycling ◽  
Ussing Chambers

The aim of this work was to study acute alterations of the enterohepatic recirculation (EHR) of bile acids 3 days after an 8-Gy radiation exposure in vivo in the rat by a washout technique. Using this technique in association with HPLC analysis, the EHR of the major individual bile acids was determined in control and irradiated animals. Ex vivo ileal taurocholate absorption was also studied in Ussing chambers. Major hepatic enzyme activities involved in bile acid synthesis were also measured. Measurements of bile acid intestinal content and intestinal absorption efficiency calculation from washout showed reduced intestinal absorption with significant differences from one bile acid to another: absorption of taurocholate and tauromuricholate was decreased, whereas absorption of the more hydrophobic taurochenodeoxycholate was increased, suggesting that intestinal passive diffusion was enhanced, whereas ileal active transport might be reduced. Basal hepatic secretion was increased only for taurocholate, in accordance with the marked increase of CYP8B1 activity in the liver. The results are clearly demonstrate that concomitantly with radiation-induced intestinal bile acid malabsorption, hepatic bile acid synthesis and secretion are also changed. A current working model for pathophysiological changes in enterohepatic recycling after irradiation is thus proposed.Key words: irradiation, bile acids, intestine, liver, enterohepatic recycling.

scholarly journals Manipulating the Microbiome: An Alternative Treatment for Bile Acid Diarrhoea

2021 ◽  
Vol 12 (2) ◽  
pp. 335-353
Author(s):  
Evette B. M. Hillman ◽  
Sjoerd Rijpkema ◽  
Danielle Carson ◽  
Ramesh P. Arasaradnam ◽  
Elizabeth M. H. Wellington ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Gastrointestinal Disease ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Bile Acid Metabolism ◽  
The United Kingdom ◽  
The 1960S ◽  
Irritable Bowel ◽  
The Uk

Bile acid diarrhoea (BAD) is a widespread gastrointestinal disease that is often misdiagnosed as irritable bowel syndrome and is estimated to affect 1% of the United Kingdom (UK) population alone. BAD is associated with excessive bile acid synthesis secondary to a gastrointestinal or idiopathic disorder (also known as primary BAD). Current licensed treatment in the UK has undesirable effects and has been the same since BAD was first discovered in the 1960s. Bacteria are essential in transforming primary bile acids into secondary bile acids. The profile of an individual’s bile acid pool is central in bile acid homeostasis as bile acids regulate their own synthesis. Therefore, microbiome dysbiosis incurred through changes in diet, stress levels and the introduction of antibiotics may contribute to or be the cause of primary BAD. This literature review focuses on primary BAD, providing an overview of bile acid metabolism, the role of the human gut microbiome in BAD and the potential options for therapeutic intervention in primary BAD through manipulation of the microbiome.

scholarly journals Liver Bile Acid Changes in Mouse Models of Alzheimer’s Disease

2021 ◽  
Vol 22 (14) ◽  
pp. 7451
Author(s):  
Harpreet Kaur ◽  
Drew Seeger ◽  
Svetlana Golovko ◽  
Mikhail Golovko ◽  
Colin Kelly Combs
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Bile Acid ◽  
Bile Acids ◽  
Cholesterol Metabolism ◽  
Amyloid Β ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Liver Cholesterol ◽  
Bile Acid Metabolism

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by progressive cognitive impairment. It is hypothesized to develop due to the dysfunction of two major proteins, amyloid-β (Aβ) and microtubule-associated protein, tau. Evidence supports the involvement of cholesterol changes in both the generation and deposition of Aβ. This study was performed to better understand the role of liver cholesterol and bile acid metabolism in the pathophysiology of AD. We used male and female wild-type control (C57BL/6J) mice to compare to two well-characterized amyloidosis models of AD, APP/PS1, and AppNL-G-F. Both conjugated and unconjugated primary and secondary bile acids were quantified using UPLC-MS/MS from livers of control and AD mice. We also measured cholesterol and its metabolites and identified changes in levels of proteins associated with bile acid synthesis and signaling. We observed sex differences in liver cholesterol levels accompanied by differences in levels of synthesis intermediates and conjugated and unconjugated liver primary bile acids in both APP/PS1 and AppNL-G-F mice when compared to controls. Our data revealed fundamental deficiencies in cholesterol metabolism and bile acid synthesis in the livers of two different AD mouse lines. These findings strengthen the involvement of liver metabolism in the pathophysiology of AD.

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.

Abstract 49: The Transcriptional Repressor MafG Regulates Cholesterol Catabolism

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Thomas Q de Aguiar Vallim ◽  
Elizabeth J Tarling ◽  
Hannah Ahn ◽  
Lee R Hagey ◽  
Casey E Romanoski ◽  
...  
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Acid Metabolism ◽  
Metabolic Diseases ◽  
Cholesterol Metabolism ◽  
Transcriptional Repressor ◽  
Acid Synthesis ◽  
Bile Acid Synthesis ◽  
Bile Acid Metabolism ◽  
Biliary Bile Acid

Elevated circulating cholesterol levels is a major risk factor for cardiovascular diseases (CVD), and therefore understanding pathways that affect cholesterol metabolism are important for potential treatment of CVD. The major route for cholesterol excretion is through its catabolism to bile acids. Specific bile acids are also potent signaling molecules that modulate metabolic pathways affecting lipid, glucose and bile acid homeostasis. Bile acids are synthesized from cholesterol in the liver, and the key enzymes involved in bile acid synthesis ( Cyp7a1 , Cyp8b1 ) are regulated transcriptionally by the nuclear receptor FXR. We have identified an FXR-regulated pathway upstream of a transcriptional repressor that controls multiple bile acid metabolism genes. We identify MafG as an FXR target gene and show that hepatic MAFG overexpression represses genes of the bile acid synthetic pathway, and modifies the biliary bile acid composition. In contrast, MafG loss-of-function studies cause de-repression of the bile acid genes with concordant changes in biliary bile acid levels. Finally, we identify functional MafG response elements in bile acid metabolism genes using ChIP-Seq analysis. Our studies identify a molecular mechanism for the complex feedback regulation of bile acid synthesis controlled by FXR. The identification of this pathway will likely have important implications in metabolic diseases.

Sign in / Sign up

Export Citation Format

Share Document