Bile Acid Excretion Research Articles

Gardenia extract protects against intrahepatic cholestasis by regulating bile acid enterohepatic circulation

Ethnopharmacological relevanceCholestasis is the main manifestation of cholestatic liver disease, which has a risk of progression to end-stage liver disease. Gardeniae Fructus is the dried fruit of Gardeniae jasminoides Ellis, a plant of the Rubiaceae family. Gardeniae Fructus has shown therapeutic potential in cholestasis-related liver diseases and it is generally believed that Gardeniae Fructus ameliorates cholestasis, which could be related to its influence on bile acids (BAs) metabolism. However, the specific targets of Gardeniae Fructus and its impact on enterohepatic circulation of BAs have not yet been fully elucidated. Aim of the studyTo systematically elucidate the mechanism by which Gardenia extract (GE, total iridoids in Gardeniae Fructus, which contains the predominant and characteristic phytoconstituents of Gardeniae Fructus) ameliorates alpha-naphthylisothiocyanate (ANIT)-induced cholestatic liver injury. Materials and methodsSprague-Dawley rats were orally administered water, obeticholic acid (OCA, 2 mg/kg), or GE (21 and 42 mg/kg) once daily for five days. On the third day, the model was established by administration of a single dose of ANIT (40 mg/kg) by oral gavage. Biochemical and pathological analyses, BA metabolomics, transcriptomics, and qRT-PCR were performed. ResultsThe profile of BAs in serum and liver confirmed that GE attenuated ANIT-induced acute cholestasis by affecting BA metabolism in a dose-dependent manner. Liver transcriptomic analysis indicated that GE mainly influenced the primary bile acid (PBA) biosynthesis and bile secretion pathways. GE mainly affected PBA biosynthesis in liver by upregulating Cyp8b1 gene expression, thereby significantly reducing the level of total bile acids (TBA). GE mainly promoted PBA excretion from liver into duodenum by upregulating Fxr and Oatp1 gene expression, thereby increasing the excretion of PBA in feces, and inhibiting PBA in liver entering the blood by alternative routes to reduce TBA levels in serum and urine and improve the enterohepatic circulation of BAs. ConclusionGE attenuated ANIT-induced hepatotoxicity and cholestasis in rats by upregulating Cyp8b1 expression to inhibit BA synthesis in the liver, while also promoting BA excretion via the intestinal-fecal route, and improving enterohepatic circulation of BAs.

Fucus vesiculosus polysaccharide alleviates type 2 diabetes in rats via remodeling gut microbiota and regulating glycolipid metabolism-related gene expression

The antidiabetic activity and underlying mechanisms of Fucus vesiculosus polysaccharide (FVP) were studied in type 2 diabetic rats. Our results exhibited that FVP intervention reversed body weight loss, alleviated hyperglycemia and insulin resistance in diabetic rats. FVP also had the potential to ameliorate dyslipidemia, liver and kidney dysfunction, decrease oxidative stress, promote glycogen synthesis, and boost short-chain fatty acid production and total bile acid excretion. 16S rRNA gene sequencing analysis suggested that FVP interfered with the gut microbiota in a beneficial manner. Moreover, RT-qPCR results demonstrated that the antidiabetic activity of FVP in connection with the acceleration of blood glucose absorption and glycogen synthesis, the inhibition of gluconeogenesis, and the regulation of lipid metabolism in the liver. These findings suggested that FVP had antidiabetic effects on high-fat diet and STZ-induced diabetic rats and could be a potential resource for treating type 2 diabetes mellitus.

Identifying hepatoprotective mechanism and effective components of Yinchenzhufu decoction in chronic cholestatic liver injury using a comprehensive strategy based on metabolomics, molecular biology, pharmacokinetics, and cytology

Ethnopharmacological relevanceIn Traditional Chinese Medicine (TCM), cholestasis liver disease belongs to jaundice. Yinchenzhufu decoction (YCZFD) is a classic formula used for treating jaundice. Aim of the studyThis study was aimed to investigate the potential mechanism and effective components of YCZFD in chronic cholestatic liver injury (CCLI). Materials and methodsA chronic cholestatic mouse model induced by 3, 5-diethoxycarbonyl-1, 4-dihydroxychollidine was used to investigate the effect of YCZFD. Then, metabolomics was used to investigate the metabolites influenced by YCZFD. Serum and liver bile acid (BA) levels were measured using liquid chromatography coupled with triple quadruple mass spectrometry (LC-MS/MS), and the gene and protein expressions of BA transporters and metabolic enzymes were detected. Additionally, the pharmacokinetics of multiple components of YCZFD was explored to clarify the potential effective components. The effects of absorbed components of YCZFD on BA metabolism and transporter function, inflammation, and farnesoid X receptor (FXR) and pregnane X receptor (PXR) activation were analyzed using sandwich cultured rat hepatocytes, AML12 cells, and dual-luciferase receptor systems, respectively. ResultsYCZFD decreased the liver damage in chronic cholestatic mice. Serum metabolomics results indicated that the main pathways influenced by YCZFD involved primary BA biosynthesis and arachidonic acid metabolism. YCZFD upregulated the expression of FXR, PXR, and BA efflux transporters and the metabolic enzymes of liver tissues, promoting BA excretion and metabolism in cholestatic mice. Additionally, YCZFD downregulated the expression of genes and proteins of the toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) pathway and decreased liver inflammation. The pharmacokinetic study indicated that multiple components showed different pharmacokinetic properties. Among the absorbed components of YCZFD, multiple components activated the transcription of FXR and PXR, regulated BA transporters and metabolic enzyme function, and reduced the gene expression of TLR4 and NF-κB1. ConclusionYCZFD can ameliorate CCLI by promoting the excretion and metabolism of BAs and inhibiting inflammation via the TLR4/NF-κB signaling pathway. The multiple components of YCZFD could act on BA homeostasis regulation and anti-inflammation, exhibiting a combined effect against CCLI.

Peripheral Vascular Disease and Carotid Artery Disease Are Associated with Decreased Bile Acid Excretion.

Low bile acid excretion (BAE) is associated with a higher risk of coronary artery disease (CAD) and cerebrovascular disease (stroke). This study investigated BAE in patients with peripheral vascular disease (PVD) and carotid artery disease (CA) and those without these diseases, compared to patients with CAD, stroke, or no evidence of atherosclerosis. Patients with complaints of chest pain-suspected CAD, syncope, stroke/TIA, severe headache, intermittent claudication, or falls were enrolled. All received a 4-day standard diet with 490 mg of cholesterol and internal standard copper thiocyanate. Fecal BAE was measured using gas-liquid chromatography. One hundred and three patients, sixty-eight (66%) men and thirty-five women (34%), mean age range 60.9 ± 8.9 years, were enrolled in this prospective, 22-year follow-up study. Regression analysis showed that advanced age, total BAE, and excretion of the main fractions were the only significant independent factors that predicted prolonged survival (p < 0.001). Twenty-two years' follow-up revealed only 15% of those with BAE <262.4 mg/24 h survived, compared to >60% of participants without atherosclerosis and a mean BAE of 676 mg/24 h. BAE was lower in patients with polyvascular atherosclerosis than in those with involvement of 1-3 vascular beds. Pearson correlations were found between total BAE and various fractions of BA, as well as HDL cholesterol. BAE and short-term survival were decreased among patients with PVD compared to those with CAD or stroke. Low BAE should be considered a valuable and independent risk factor for PVD.

Molecular mechanisms of hepatoprotective effect of tectorigenin against ANIT-induced cholestatic liver injury: Role of FXR and Nrf2 pathways.

Cholestatic liver injury is caused by toxic action or allergic reaction, resulting in abnormality of bile formation and excretion. Few effective therapies have become available for the treatment of cholestasis. Herein, we found that tectorigenin (TG), a natural isoflavone, showed definite protective effects on alpha-naphthylisothiocyanate (ANIT)-induced cholestatic liver injury, significantly reversing the abnormality of plasma alanine/aspartate aminotransferase, total/direct bilirubin and alkaline phosphatase, as well as hepatic reactive oxygen species, catalase and superoxide dismutase. Importantly, the targeted metabolomic determination found that BA homeostasis could be well maintained in TG-treated cholestatic mice, especially the levels of glycocholic acid, tauromuricholic acid, taurocholic acid, taurolithocholic acid, tauroursodeoxycholic acid and taurodeoxycholic acid. Overall, primary/secondary and amidated/unamidated bile acid (BA) levels were significantly altered upon ANIT stimulation but could be restored by TG intervention to certain extents. In addition, TG boosted the expression of farnesoid x receptor (FXR), which in turn upregulated multidrug resistance protein 2 (MRP2) and bile salt export pump (BSEP) to accelerate the excretion of BA. Meanwhile, TG enhanced the expression of Nrf2 and its upstream genes PI3K/Akt and downstream target genes HO-1, NQO1, GCLC and GCLM to strengthen the antioxidant capacity. Taken together, TG plays a vital role in maintaining BA homeostasis and ameliorating cholestatic liver injury through regulating FXR-mediated BA efflux and Nrf2-mediated antioxidative pathways.

Multi‑omics‑based analysis of the regulatory mechanism of gypenosides on bile acids in hypercholesterolemic mice.

Gynostemma pentaphyllum is a traditional medicine used by ethnic minorities in southwest China and gypenosides are currently recognized as essential components of the pharmacological substances of Gynostemma pentaphyllum, which are effective in regulating metabolic syndrome, especially in improving hepatic metabolic disorders. The present study randomly divided C57BL/6J male mice into the normal diet control group (ND), high-fat diet modeling group (HFD) and gypenosides group (GP). Liquid chromatography-mass spectrometry (UPLC-MS) was applied to quantify bile acids in the liver, bile and serum of mice in ND, HFD and GP groups. Liver proteins were extracted for trypsin hydrolysis and analyzed quantitatively using UPLC-MS + MS/MS (timsTOF Pro 2). Total mouse liver RNA was extracted from ND, HFD and GP groups respectively, cDNA sequencing libraries constructed and sequenced using BGISEQ-500 sequencing platform. The expression of key genes Fxr, Shp, Cyp7a1, Cyp8b1, and Abab11 was detected by RT-qPCR. The results showed that gypenosides accelerated free bile acid synthesis by promoting the expression of bile acid synthase CYP7A1 and CYP8B1 genes and proteins and accelerating the secretion of conjugated bile acids from the liver to the bile ducts. GP inhibited the bile acid transporters solute carrier organic anion transporter family member (SLCO) 1A1 and SLCO1A4, reducing the reabsorption of free bile acids and accelerating the excretion of free bile acids from the blood to the kidneys. It also promoted the metabolic enzyme CYP3A11, which accelerated the metabolism and clearance of bile acids, thus maintaining the balance of the bile acid internal environment.

Inulin ameliorates metabolic syndrome in high-fat diet-fed mice by regulating gut microbiota and bile acid excretion.

Background: Inulin is a natural plant extract that improves metabolic syndrome by modulating the gut microbiota. Changes in the gut microbiota may affect intestinal bile acids. We suggest that inulin may improve metabolism by inducing bile acid excretion by gut microbes. Methods: Male C57/BL mice were fed either a high-fat diet (60% calories) or a regular diet for 16weeks, with oral inulin (10% w/w). At the end of the experiment, the gene expression levels (FGF15, CD36, Srebp-1c, FASN, and ACC) in the liver and intestines, as well as the serum levels of triglycerides (TGs), low-density lipoprotein (LDL) cholesterol, total cholesterol, and free fatty acids, were collected. The expression of FGF15 was examined using Western blot analysis. The fat distribution in the liver and groin was detected by oil red and hematoxylin and eosin staining. Simultaneously, the levels of serum inflammatory factors (alanine aminotransferase and aspartate aminotransferase) were detected to explore the side effects of inulin. Results: Inulin significantly improved glucose tolerance and insulin sensitivity, and decreased body weight and serum TG and LDL levels, in mice fed normal diet. Furthermore, inulin increased the α-diversity of the gut microbiota and increased the fecal bile acid and TG excretion in inulin-treated mice. In addition, inulin significantly reduced lipid accumulation in liver and inguinal fat, white fat weight, and hepatic steatosis. Western blot analysis showed that inulin reduced the expression of FGF15, a bile acid reabsorption protein. Conclusion: Inulin ameliorates the glucose and lipid metabolic phenotypes of mice fed a normal diet, including decreased intestinal lipid absorption, increased glucose tolerance, increased insulin sensitivity, and decreased body weight. These changes may be caused by an increase in bile acid excretion resulting from changes in the gut microbiota that affect intestinal lipid absorption.

Taxonomic identification of bile salt hydrolase-encoding lactobacilli: Modulation of the enterohepatic bile acid profile.

Bile salt hydrolases (BSHs) are enzymes that are essential for the enterohepatic metabolism of bile acids (BAs). BSHs catalyze the production of unconjugated BAs and regulate the homeostasis of BA pool. This study identified Lactobacillus as a crucial BSH-encoding genus, and 16 main species were obtained using metagenomic data from publicly available human gut microbiome databases. Then, the 16 species of lactobacilli were classified into four typical categories by BSH phylotypes, including five species encoding BSH-T0, six species encoding BSH-T2, four species encoding BSH-T3, and Ligilactobacillussalivarius encoding both BSH-T0 and BSH-T3. The lactobacilli with the highest in vitro deconjugation activities against seven conjugated BAs were the BSH-T3-encoding strains. Furthermore, in vivo studies in mice administered four representative lactobacilli strains encoding different BSH phylotypes showed that treatment with BSH-T3-encoding Limosilactobacillusreuteri altered the structure of the gut microbiome and metabolome and significantly increased the levels of unconjugated BAs and total BA excretion. Our findings facilitated the taxonomic identification of crucial BSH-encoding lactobacilli in human gut microbiota and shed light on their contributions toward modulation of the enterohepatic circulation of BAs, which will contribute to future therapeutic applications of BSH-encoding probiotics to improve human health.

Extension Region Domain of Soybean 7S Globulin Contributes to Serum Triglyceride-Lowering Effect via Modulation of Bile Acids Homeostasis.

Soybean 7S globulin (β-conglycinin), a major soybean storage protein, has been demonstrated to exert remarkable triglyceride (TG) and cholesterol-lowering effects, yet the underlying mechanism remains controversial. A comparative investigation is performed to assess the contribution of different structural domains of soybean 7S globulin, including core region (CR) and extension region (ER) domains, to biological effects of soybean 7S globulin using a high-fat diet rat model. The results show that ER domain mainly contributes to the serum TG-lowering effect of soybean 7S globulin, but not for CR domain. Metabolomics analysis reveals that oral administration of ER peptides obviously influences the metabolic profiling of serum bile acids (BAs), as well as significantly increased the fecal excretion of total BAs. Meanwhile, ER peptides supplementation reshapes the composition of gut microbiota and impacts the gut microbiota-dependent biotransformation of BAs which indicate by a significantly increased secondary BAs concentration in fecal samples. These results highlight that TG-lowering effects of ER peptides mainly stem from their modulation of BAs homeostasis. Oral administration of ER peptides can effectively lower serum TG level by regulating BAs metabolism. ER peptides have potential to be used as a candidate pharmaceutical for the intervention of dyslipidemia.

Brassica rapa L. prevents Western diet-induced obesity in C57BL/6 mice through its binding capacity of cholesterol and fat.

Obesity, a chronic disorder caused by excessive energy intake leading to fat accumulation in adipose tissue, increases the risk of severe diseases. Brassica rapa L. is known as a traditional vegetable in the Nagano area of Japan. C57BL/6 mice were randomly assigned to three groups, with different diets as follows: a normal diet, a Western diet (WD), and a WD plus B. rapa L. powder (BP) in a 56-day experiment. Brassica rapa L. supplementation reduced the body weight gain and lipid accumulation of mice significantly. The BP group also had higher fecal bile acid, total cholesterol, and triglyceride excretion levels compared with those in the other groups. The antiobesity effects of B. rapa L. were due to its binding with cholesterol and fat, and possibly enhancing the bile acid excretion and modulating gut microbiota, suggesting thatB. rapaL. could be a functional vegetable with potential uses in targeting obesity.

Saikosaponins regulate bile acid excretion in mice liver and ileum by activating farnesoid X receptor and bile acid transporter.

Radix Bupleuri exerts effective hepatoprotective and cholagogic effects through its Saikosaponins (SSs) component. Therefore, we attempted to determine the mechanism of saikosaponins used to promote bile excretion by studying their effects on intrahepatic bile flow, focusing on the synthesis, transport, excretion, and metabolism of bile acids. C57BL/6N mice were continuously gavaged with saikosaponin a (SSa), saikosaponin b2 (SSb2 ), or saikosaponin D (SSd) (200 mg/kg) for 14 days. Liver and serum biochemical indices were determined using Enzyme-linked immunosorbent assay (ELISA) kits. In addition, an ultra-performance liquid chromatography-mass spectrometer (UPLC-MS) was used to measure the levels of the 16 bile acids in the liver, gallbladder, and cecal contents. Furthermore, SSs pharmacokinetics and docking between SSs and farnesoid X receptor (FXR)-related proteins were analyzed to investigate the underlying molecular mechanisms. Administration of SSs and Radix Bupleuri alcohol extract (ESS) did not cause significant changes in alanine aminotransferase (ALT), aspartate aminotransferase (AST), or alkaline phosphatase (ALP) levels. Saikosaponin-regulated changes in bile acid (BA) levels in the liver, gallbladder, and cecum were closely related to genes involved in BA synthesis, transport, and excretion in the liver. Pharmacokinetic studies indicated that SSs were characterized by rapid elimination (t1/2 as 0.68-2.47 h), absorption (Tmax as 0.47-0.78 h), and double peaks in the drug-time curves of SSa and SSb2 . A molecular docking study revealed that SSa, SSb2 , and SSd docked well with the 16 protein FXR molecules and target genes (<-5.2 kcal/mol). Collectively, saikosaponins may maintain BA homeostasis in mice by regulating FXR-related genes and transporters in the liver and intestine.

Effects of a 28-day feeding trial of grain-containing versus pulse-based diets on cardiac function, taurine levels and digestibility in domestic dogs.

In 2018, the US Food and Drug Administration reported a link between canine dilated cardiomyopathy (DCM) and grain-free diets. Evidence to support a link has emerged, but the specific ingredients responsible and the role of taurine or other causative factors remain unclear. We hypothesized dogs fed pulse-based, grain-free diets for 28 days will show decreased macronutrient digestibility, increased fecal bile acid excretion, and reduced plasma cystine, cysteine, methionine and taurine, causing sub-clinical cardiac or blood changes indicative of early DCM. Three diets were formulated using white rice flour (grain), whole lentil (grain-free), or wrinkled pea (grain-free) and compared to the pre-trial phase on a commercial grain-based diet. After 28 days of feeding each diet, the wrinkled pea diet impaired stroke volume and cardiac output, increased end-systolic ventricular diameter and increased plasma N-Terminal Pro-B-type Natriuretic Peptide (NT-ProBNP), albeit in a sub-clinical manner. Digestibility of some macronutrients and sulphur-containing amino acids, excluding taurine, also decreased with pulse-based compared to grain-based diets, likely due to higher fiber levels. Plasma taurine levels were unchanged; however, plasma methionine was significantly lower after feeding all test diets compared to the commercial diet. Overall, DCM-like changes observed with the wrinkled pea diet, but not lentil diet, after only 4 weeks in a breed not known to be susceptible support a link between pea-based diets and canine nutritionally-mediated DCM.

Intermittent fasting alleviates non-alcoholic steatohepatitis by regulating bile acid metabolism and promoting fecal bile acid excretion in high-fat and high-cholesterol diet fed mice.

Intermittent fasting (IF) has a protective role across a wide range of chronic disorders, including obesity, diabetes and cardiovascular disease, but its protection against non-alcoholic steatohepatitis (NASH) is still lacking. This study sought to investigate how IF alleviates NASH by regulating gut microbiota and bile acids (BAs) composition. Male C57BL/6 mice were fed a high-fat and high-cholesterol (HFHC) diet for 16 weeks to establish a NASH model. Mice then continued HFHC feeding and were treated with or without every other day fasting for 10 weeks. Hepatic pathology was assessed using hematoxylin-eosin staining. Gut microbiota of the cecum were profiled using 16S rRNA gene sequencing and the levels of BAs in serum, colon contents, and feces were measured using UPLC-MS/MS. Results indicated that IF significantly decreased murine body weight, insulin resistance, hepatic steatosis, ballooning, and lobular inflammation. IF reshaped the gut microbiota, reduced the accumulation of serum BAs, and increased total colonic and fecal BAs. Moreover, IF increased the expression of cholesterol 7α-hydroxylase 1 in liver, but decreased the expressions of both farnesoid-X-receptor and fibroblast growth factor 15 in the ileum. IF alleviated NASH by regulating bile acid metabolism and promoting fecal bile acid excretion. This article is protected by copyright. All rights reserved.

Bacteroides dorei BDX-01 alleviates DSS-induced experimental colitis in mice by regulating intestinal bile salt hydrolase activity and the FXR-NLRP3 signaling pathway.

Background: The relationships among intestinal dysbiosis, bile acid (BA) metabolism disorders, and ulcerative colitis pathogenesis are now recognized. However, how specific strains regulate BA metabolism to alleviate colitis is still unclear. This study investigated the effects of Bacteroides dorei on the development of acute colitis and elucidated the underlying mechanisms. Methods: The safety of BDX-01 was evaluated in vitro and in vivo. 2.5% dextran sulfate sodium (DSS) induced colitis in C57BL/6 mice, Caco-2, and J774A.1 cells were used to evaluate the anti-inflammatory effect of BDX-01. qPCR and Western blotting were used to detect the expression of inflammatory pathways. Microbiota composition was analyzed by 16S rRNA gene sequencing. Enzyme activity analysis and targeted metabolomics were used to analyze fecal bile salt hydrolase (BSH) and BA levels. Antibiotic-induced pseudo-germ-free mice were used to investigate the role of gut microbiota in the alleviation of colitis by BDX-01. Results: We confirmed the safety of novel strain Bacteroides dorei BDX-01 in vitro and in vivo. Oral BDX-01 administration significantly ameliorated the symptoms and pathological damage of DSS-induced acute colitis. Moreoever, 16S rRNA sequencing and enzyme activity analysis showed that BDX-01 treatment increased intestinal BSH activity and the abundance of bacteria harboring this enzyme. Targeted metabolomics revealed that BDX-01 significantly increased intestinal BA excretion and deconjugation. Certain BAs act as FXR agonists. The β-muricholic acid (βMCA): taurine β-muricholic acid (T-βMCA) and cholic acid (CA): taurocholic acid (TCA) ratios and the deoxycholic acid (DCA) level decreased markedly in the colitis models but increased substantially in BDX-01-treated mice. The colonic farnesoid X receptor (FXR) and fibroblast growth factor 15 (FGF15) were upregulated in mice treated with BDX-01. BDX-01 downregulated the expression of colonic proinflammatory cytokines pyrin domain-containing 3 (NLRP3), ASC, cleaved caspase-1, and IL-1β. Antibiotic treatment didn't abolish the protective effect of BDX-01 on colitis. In vitro studies showed TβMCA abolished the effects of BDX-01 on FXR activation and inhibition of the NLRP3 inflammasome activation. Conclusion: BDX-01 improved DSS-induced acute colitis by regulating intestinal BSH activity and the FXR-NLRP3 signaling pathway. Our findings indicate that BDX-01 is a promising probiotic to improve the management of ulcerative colitis.

Gentamicin alleviates cholestatic liver injury by decreasing gut microbiota-associated bile salt hydrolase activity in rats

Intrahepatic cholestasis lacks effective therapeutic drugs. The gut microbiota-associated bile salt hydrolases (BSH) may be a potential therapeutic target. In this study, oral administration of gentamicin (GEN) decreased the serum and hepatic levels of total bile acid in 17α-ethynylestradiol (EE)-induced cholestatic male rats, significantly improved the serum levels of hepatic biomarkers and reversed the histopathological changes in the liver. In healthy male rats, the serum and hepatic levels of total bile acid were also decreased by GEN, the ratio of primary to secondary bile acids, and conjugated to unconjugated bile acids was significantly increased, and the urinary excretion of total bile acid was elevated. 16S rDNA sequencing of the ileal contents revealed that GEN treatment substantially reduced the abundance of Lactobacillus and Bacteroides both of which expressed BSH. Consistently, BSH activity analysis by the generation of d5-chenodeoxycholic acid from d5-taurochenodeoxycholic acid in situ showed BSH was significantly inhibited in the ileal contents of rats treated with GEN. This finding led to an increased proportion of hydrophilic conjugated bile acids and facilitated the urinary excretion of total bile acids, thereby decreasing serum and hepatic total bile acids and reversing liver injury related to cholestasis. Our results provide important evidence that BSH can be a potential drug target for treating cholestasis.

Glycine-β-Muricholic Acid Improves Liver Fibrosis and Gut Barrier Function by Reducing Bile Acid Pool Size and Hydrophobicity in Male Cyp2c70 Knockout Mice.

Cyp2c70 knockout mice lack the enzyme that produces muricholic acids and show a "human-like" hydrophobic bile acid pool-induced hepatobiliary injury. In this study, we investigated the potential anti-cholestasis effect of glycine-conjugated β muricholic acid (G-β-MCA) in male Cyp2c70 KO mice based on its hydrophilic physiochemical property and signaling property as an farnesoid X receptor (FXR) antagonist. Our results showed that G-β-MCA treatment for 5 weeks alleviated ductular reaction and liver fibrosis and improved gut barrier function. Analysis of bile acid metabolism suggested that exogenously administered G-β-MCA was poorly absorbed in the small intestine and mostly deconjugated in the large intestine and converted to taurine-conjugated MCA (T-MCA) in the liver, leading to T-MCA enrichment in the bile and small intestine. These changes decreased the biliary and intestine bile acid hydrophobicity index. Furthermore, G-β-MCA treatment decreased intestine bile acid absorption via unknown mechanisms, resulting in increased fecal bile acid excretion and a reduction in total bile acid pool size. In conclusion, G-β-MCA treatment reduces the bile acid pool size and hydrophobicity and improves liver fibrosis and gut barrier function in Cyp2c70 KO mice.

Dietary Isoquercetin Reduces Hepatic Cholesterol and Triglyceride in NAFLD Mice by Modulating Bile Acid Metabolism via Intestinal FXR-FGF15 Signaling

Isoquercetin, a monosaccharide flavonoid, was recently reported to have significant amelioration effects on high-fat diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD) of mice. However, the underlying mechanism of hepatic cholesterol and triglyceride improvement in mice fed HFD by isoquercetin remains unclear. Here, a combination of 16S rRNA gene sequencing, targeted quantification of bile acids (BAs), and biological assays was employed to investigate the beneficial effects of isoquercetin on NAFLD in mice. The results showed that dietary isoquercetin markedly modulated the BAs profiling in various samples such as liver, serum, intestine, and feces. We found that dietary isoquercetin promoted BA biosynthesis via the activation of alternative pathways and inhibition of intestinal FXR-Fgf15 signaling, thus reducing 13.2% hepatic cholesterol and 16.05% triglyceride in NAFLD mice. Dietary isoquercetin also regulated a series of receptors mediating correspondent processes of BA transportation, reabsorption, and excretion. Of particular note, dietary isoquercetin significantly modulated cross-talk between BAs and specific gut bacteria of NAFLD mice. These findings revealed that long-term intake of isoquercetin plays beneficial roles in the prevention or intervention of fatty liver disease.

Polysaccharide from Angelica sinensis with medicinal and edible purposes ameliorated NAFLD by the bile acids mediated activation of FXR

Liver and gut communicates with each other through metabolites and the gut-liver axis plays a crucial role in lipid metabolism. Enterohepatic bile acid circulation is an important constitution of gut-liver axis. Farnesoid X receptor (FXR)，a bile acid mediated nuclear receptor, is promising therapeutic targets for the non-alcoholic fatty liver disease (NAFLD). More and more studies have confirmed the effects of Angelica sinensis polysaccharide (ASP) on liver protection and lipid regulation. However, little attention has been paid to the role of ASP on the gut-liver axis, which is crucial to clarify how ASP play a role in liver protection after oral administration. In vivo and in vitro models of NAFLD were established to examine the effect of ASP on hepatic fat accumulation. Our results showed that ASP could alleviate liver fat accumulation. However, the expression of FXR was not changed when ASP directly acting on hepatocytes, while ASP could change the expression of FXR in liver and intestine of mice after oral administration. In addition, our results showed that ASP could promote the excretion of bile acids, thereby increasing cholesterol metabolism. Our research provided a new concept for the mechanism of ASP regulating liver lipid metabolism and exerting liver protection.

Prevention of High-Fat-Diet-Induced Dyslipidemia byLactobacillus plantarumLP104 through Mediating Bile Acid Enterohepatic Axis Circulation and Intestinal Flora

This work aimed to investigate the alleviative mechanism of Lactobacillus plantarum LP104 (LP104) isolated from kimchi on high-fat-diet-induced dyslipidemia by targeting the intestinal flora and bile acid (BA) metabolism. Oral administration of LP104 over 8 weeks reduced body weight gain and body fat, as well as ameliorating serum and hepatic dyslipidemia in HFD-fed C57BL/6N mice significantly. LP104 intervention also increased the ileal tauro-α/β-muricholic acid sodium salt (T-α-MCA or T-β-MCA) and tauroursodeoxycholic acid (TUDCA) concentrations to suppress the enterohepatic farnesoid X receptor/fibroblast growth factor 15-fibroblast growth factor receptor 4 (FXR/FGF15-FGFR4) signaling pathway, which stimulated the hepatic cholic acid (CA) and chenodeoxycholic acid (CDCA) de novo synthesis through using cholesterol. Then, LP104 treatment accelerated BA excretion with the feces and cholesterol efflux to improve HFD-caused hyperlipidemia effectively. The 16S rRNA gene high-throughput sequencing revealed that LP104 promoted intestinal flora rebalance by increasing the abundances of Bacteroides, Akkermansia, Lactobacillus, and Clostridium and decreasing the abundance of Oscillospira and Coprococcus. Meanwhile, Spearman correlation analysis demonstrated that the differential flora were closely related to BA signaling molecules including CA, CDCA, T-α-MCA, T-β-MCA, and TUDCA after LP104 intervention. These findings provided new evidence that LP104 had the potential to be used as a naturally functional food for the prevention of dyslipidemia.

Bile Acid Alterations Characterize the Early Onset and Progression of Nonalcoholic Fatty Liver Disease in Young Mice Fed with High Fat and Fructose Diet.

Bile acids (BAs) are closely associated with obesity and non-alcoholic fatty liver disease (NAFLD). How BAs change within the enterohepatic circulation during the onset and progression of NAFLD as biomarkers deserves to be explored. Four-week-old young mice were fed with high-fat diet plus 4% v/w fructose drinking water (HFF) or normal diet with tap water (ND) for 4 and 12 weeks. In comparison, eight-week-old adult mice were fed with HFF or ND for 12 weeks. BAs were measured in six different anatomical sites to evaluate the systematic changes of BAs within the enterohepatic circulation. The dysregulated BA metabolism had occurred in HFF after 4-week intervention, represented by increased primary BAs and decreased hyocholic acid (HCA) species. After 12 weeks, the impact was more significant with increased secondary BA synthesis and excretion, particularly for lithocholic acid (LCA) species. More interestingly, the BA changes were more significant in younger mice in response to 12-week diet intervention. The enterohepatic circulation of BAs changed with the development of NAFLD, and the younger mice were more susceptible to the unhealthy diet. HCA and LCA species may be potential biomarkers for predicting the development of NAFLD.