FXR signaling in the enterohepatic system

Liquid Chromatography/Tandem Mass Spectrometry-Based Simultaneous Analysis of 32 Bile Acids in Plasma and Conventional Biomarker-Integrated Diagnostic Screening Model Development for Hepatocellular Carcinoma

Imaging tests, tumor marker (TM) screening, and biochemical tests provide a definitive diagnosis of hepatocellular carcinoma (HCC). However, some patients with HCC may present TM-negative results, warranting a need for developing more sensitive and accurate screening biomarkers. Various diseases exhibit increased blood levels of bile acids, biosynthesized from cholesterol in the liver, and they have been associated with HCC. Herein, we analyzed plasma bile acids using liquid chromatography/tandem mass spectrometry and integrated them with conventional biomarkers to develop a diagnostic screening model for HCC. Plasma samples were obtained from patients diagnosed with chronic hepatitis, hepatic cirrhosis (HC), and HCC. A QTRAP 6500 mass spectrometer and a Nexera liquid chromatograph with a YMC-Triart C18 analytical column were used. The mobile phase A was a 20 mmol/L ammonium formate solution, and mobile phase B was a methanol/acetonitrile mixture (1:1, v/v) with 20 mmol/L ammonium formate. After determining the concentrations of 32 bile acids, statistical analysis and diagnostic screening model development were performed. Plasma concentrations of bile acids differed between sample groups, with significant differences observed between patients with HC and HCC. By integrating bile acid results with conventional biochemical tests, a potential diagnostic screening model for HCC was successfully developed. Future studies should increase the sample size and analyze the data in detail to verify the diagnostic efficacy of the model.

Molecular mechanism and therapeutic strategy of bile acids in Alzheimer's disease from the emerging perspective of the microbiota-gut-brain axis

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of amyloid-β outside neurons and Tau protein inside neurons. Various pathological mechanisms are implicated in AD, including brain insulin resistance, neuroinflammation, and endocrinal dysregulation of adrenal corticosteroids. These factors collectively contribute to neuronal damage and destruction. Recently, bile acids (BAs), which are metabolites of cholesterol, have shown neuroprotective potential against AD by targeting the above pathological changes. BAs can enter the systematic circulation and cross the blood-brain barrier, subsequently exerting neuroprotective effects by targeting several endogenous receptors. Additionally, BAs interact with the microbiota-gut-brain (MGB) axis to improve immune and neuroendocrine function during AD episodes. Gut microbes impact BA signaling in the brain through their involvement in BA biotransformation. In this review, we summarize the role and molecular mechanisms of BAs in AD while considering the MGB axis and propose novel strategies for preventing the onset and progression of AD.

Emerging drugs for the treatment of progressive familial intrahepatic cholestasis: a focus on phase II and III trials

INTRODUCTION

Progressive familial intrahepatic cholestasis (PFIC) is a group of disorders characterized by inappropriate bile formation, causing hepatic accumulation of bile acids and, subsequently, liver injury. Until recently, no approved treatments were available for these patients.

AREAS COVERED

Recent clinical trials for PFIC treatment have focused on intestine-restricted ileal bile acid transporter (IBAT) inhibitors. These compounds aim to reduce the pool size of bile acids by interrupting their enterohepatic circulation. Other emerging treatments in the pipeline include systemic IBAT inhibitors, synthetic bile acid derivatives, compounds targeting bile acid synthesis via the FXR/FGF axis, and chaperones/potentiators that aim to enhance the residual activity of the mutated transporters.

EXPERT OPINION

Substantial progress has been made in drug development for PFIC patients during the last couple of years. Although data concerning long-term efficacy are as yet only scarcely available, new therapies have demonstrated robust efficacy in a considerable fraction of patients at least on the shorter term. However, a substantial fraction of PFIC patients do not respond to these novel therapies and thus still requires surgical treatment, including liver transplantation before adulthood. Hence, there is still an unmet medical need for long-term effective medical, preferably non-surgical, treatment for all PFIC patients.

Butylparaben induces glycolipid metabolic disorders in mice via disruption of gut microbiota and FXR signaling

Butylparaben, a common preservative, is widely used in food, pharmaceuticals and personal care products. Epidemiological studies have revealed the close relationship between butylparaben and diabetes; however the mechanisms of action remain unclear. In this study, we administered butylparaben orally to mice and observed that exposure to butylparaben induced glucose intolerance and hyperlipidemia. RNA sequencing results demonstrated that the enrichment of differentially expressed genes was associated with lipid metabolism, bile acid metabolism, and inflammatory response. Western blot results further validated that butylparaben promoted hepatic lipogenesis, inflammation, gluconeogenesis, and insulin resistance through the inhibition of the farnesoid X receptor (FXR) pathway. The FXR agonists alleviated the butylparaben-induced metabolic disorders. Moreover, 16 S rRNA sequencing showed that butylparaben reduced the abundance of Bacteroidetes, S24-7, Lactobacillus, and Streptococcus, and elevated the Firmicutes/Bacteroidetes ratio. The gut microbiota dysbiosis caused by butylparaben led to decreased bile acids (BAs) production and increased inflammatory response, which further induced hepatic glycolipid metabolic disorders. Our results also demonstrated that probiotics attenuated butylparaben-induced disturbances of the gut microbiota and hepatic metabolism. Taken collectively, the findings reveal that butylparaben induced gut microbiota dysbiosis and decreased BAs production, which further inhibited FXR signaling, ultimately contributing to glycolipid metabolic disorders in the liver.

Exposure of Ldlr-/- Mice to a PFAS Mixture and Outcomes Related to Circulating Lipids, Bile Acid Excretion, and the Intestinal Transporter ASBT

BACKGROUND

Previous epidemiological studies have repeatedly found per- and polyfluoroalkyl substances (PFAS) exposure associated with higher circulating cholesterol, one of the greatest risk factors for development of coronary artery disease. The main route of cholesterol catabolism is through its conversion to bile acids, which circulate between the liver and ileum via enterohepatic circulation. Patients with coronary artery disease have decreased bile acid excretion, indicating that PFAS-induced impacts on enterohepatic circulation may play a critical role in cardiovascular risk.

OBJECTIVES

Using a mouse model with high levels of low-density and very low-density lipoprotein (LDL and VLDL, respectively) cholesterol and aortic lesion development similar to humans, the present study investigated mechanisms linking exposure to a PFAS mixture with increased cholesterol.

METHODS

Male and female L d l r - / - mice were fed an atherogenic diet (Clinton/Cybulsky low fat, 0.15% cholesterol) and exposed to a mixture of 5 PFAS representing legacy, replacement, and emerging subtypes (i.e., PFOA, PFOS, PFHxS, PFNA, GenX), each at a concentration of 2 mg / L , for 7 wk. Blood was collected longitudinally for cholesterol measurements, and mass spectrometry was used to measure circulating and fecal bile acids. Transcriptomic analysis of ileal samples was performed via RNA sequencing.

RESULTS

After 7 wk of PFAS exposure, average circulating PFAS levels were measured at 21.6, 20.1, 31.2, 23.5, and 1.5 μ g / mL in PFAS-exposed females and 12.9, 9.7, 23, 14.3, and 1.7 μ g / mL in PFAS-exposed males for PFOA, PFOS, PFHxS, PFNA, and GenX, respectively. Total circulating cholesterol levels were higher in PFAS-exposed mice after 7 wk (352 mg / dL vs. 415 mg / dL in female mice and 392 mg / dL vs. 488 mg / dL in male mice exposed to vehicle or PFAS, respectively). Total circulating bile acid levels were higher in PFAS-exposed mice (2,978  pg / μ L vs. 8,496  pg / μ L in female mice and 1,960  pg / μ L vs. 4,452  pg / μ L in male mice exposed to vehicle or PFAS, respectively). In addition, total fecal bile acid levels were lower in PFAS-exposed mice (1,797  ng / mg vs. 682  ng / mg in females and 1,622  ng / mg vs. 670  ng / mg in males exposed to vehicle or PFAS, respectively). In the ileum, expression levels of the apical sodium-dependent bile acid transporter (ASBT) were higher in PFAS-exposed mice.

DISCUSSION

Mice exposed to a PFAS mixture displayed higher circulating cholesterol and bile acids perhaps due to impacts on enterohepatic circulation. This study implicates PFAS-mediated effects at the site of the ileum as a possible critical mediator of increased cardiovascular risk following PFAS exposure. https://doi.org/10.1289/EHP14339.

Farnesoid X Receptor: Effective alleviation of rifampicin -induced liver injury

Antituberculosis drugs induce pharmacologic cholestatic liver injury with long-term administration. Liver injury resulting from rifampicin is potentially related to the bile acid nuclear receptor Farnesoid X Receptor (FXR). To investigate this, cholestasis was induced in both wild-type (C57BL/6N) mice and FXR knockout (FXR-null) mice through administration of rifampicin (200 mg/kg) via gavage for 7 consecutive days. Compared with C57BL/6N mice, FXR-null mice exhibited more severe liver injury after rifampicin administration, characterized by enlarged liver size, elevated transaminases, and increased inflammation. Moreover, under rifampicin treatment, FXR knockout impairs lipid secretion and exacerbates hepatic steatosis. Significantly, the expression of metabolism molecules BSEP increased, while NTCP and CYP7A1 decreased following rifampicin administration in C57BL/6N mice, whereas these changes were absent in FXR knockout mice. Furthermore, rifampicin treatment in both C57BL/6N and FXR-null mice was associated with elevated c-Jun N-terminal kinase phosphorylation (p-JNK) levels, with a more pronounced elevation in FXR-null mice. Our study suggests that rifampicin-induced liver injury, steatosis, and cholestasis are associated with FXR dysfunction and altered bile acid metabolism, and that the JNK signaling pathway is partially implicated in this injury. Based on these results, we propose that FXR might be a novel therapeutic target for addressing drug-induced liver injury.

Effect of Sex on Intestinal Microbial Metabolites of Hainan Special Wild Boars

The intestinal microbiota and its metabolites are essential for the health and growth development of animals. Current research indicates that sex has a certain impact on the structure and function of the intestinal microbiota, but there are few reports on sex differences in intestinal microbiota metabolites, including those of castrated male animals. This study aimed to explore the impact of sex on the intestinal microbial metabolites of Hainan special wild boars (10 entire male pigs, 10 female pigs, and 10 castrated male pigs, denoted EM, FE, and CM, respectively) by employing non-targeted metabolomics and gas chromatography. A total of 1086 metabolites were detected, with the greatest number of differential metabolites observed between EM and FE (54 differential metabolites, including 18 upregulated and 36 downregulated metabolites), the fewest between CM and FE (7 differential metabolites, including 1 upregulated and 6 downregulated metabolites), and an intermediate number between CM and EM (47 differential metabolites, including 35 upregulated and 12 downregulated metabolites). Differential metabolites were involved in more pathways between EM and FE and between CM and EM, including amino acid metabolism and digestive system pathways, whereas differential metabolites were involved in the fewest pathways between CM and FE. Correlation analysis showed Ruminococcaceae UCG-009, uncultured_bacterium_o_SAR324_cladeMarine_group_B, and Candidatus Saccharimonas contributed to the production of metabolites such as trehalose, docosatrienoic acid, D(-)-beta-hydroxy butyric acid, and acetyl-DL-leucine. The levels of acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, and isovaleric acid were significantly higher in EM than in FE, with CM falling between the two. Streptococcus, Lachnospiraceae_NK4A136_group and Rikenellaceae_RC9_gut_group showed a significant positive correlation with the production of short-chain fatty acids (SCFAs), while [Eubacterium]_coprostanoligenes_group, uncultured_bacterium_f_p-251-o5 and Ruminococcaceae_UCG-005 showed a significant negative correlation with the generation of SCFAs. This study provides foundational data and significant insights into precision feeding strategies for Hainan special wild boars of different sexes, as well as the study of sex differences in intestinal microbial metabolites in animals.

Probiotics Alleviate Microcystin-LR-Induced Developmental Toxicity in Zebrafish Larvae

Microcystin-LR (MCLR) poses a significant threat to aquatic ecosystems and public health. This study investigated the protective effects of the probiotic Lactobacillus rhamnosus against MCLR-induced developmental toxicity in zebrafish larvae. Zebrafish larvae were exposed to various concentrations of MCLR (0, 0.9, 1.8, and 3.6 mg/L) with or without L. rhamnosus from 72 to 168 h post-fertilization (hpf). Probiotic supplementation significantly improved survival, hatching, and growth rates and reduced malformation rates in MCLR-exposed larvae. L. rhamnosus alleviated MCLR-induced oxidative stress by reducing reactive oxygen species (ROS) levels and enhancing glutathione (GSH) content and catalase (CAT) activity. Probiotics also mitigated MCLR-induced lipid metabolism disorders by regulating key metabolites (triglycerides, cholesterol, bile acids, and free fatty acids) and gene expression (ppara, pparb, srebp1, and nr1h4). Moreover, 16S rRNA sequencing revealed that L. rhamnosus modulated the gut microbiome structure and diversity in MCLR-exposed larvae, promoting beneficial genera like Shewanella and Enterobacter and inhibiting potential pathogens like Vibrio. Significant correlations were found between gut microbiota composition and host antioxidant and lipid metabolism parameters. These findings suggest that L. rhamnosus exerts protective effects against MCLR toxicity in zebrafish larvae by alleviating oxidative stress, regulating lipid metabolism, and modulating the gut microbiome, providing insights into probiotic-based strategies for mitigating MCLR toxicity in aquatic organisms.

Western diet reduces small intestinal intraepithelial lymphocytes via FXR-Interferon pathway

The prevalence of obesity in the United States has continued to increase over the past several decades. Understanding how diet-induced obesity modulates mucosal immunity is of clinical relevance. We previously showed that consumption of a high fat, high sugar "Western" diet (WD) reduces the density and function of small intestinal Paneth cells, a small intestinal epithelial cell type with innate immune function. We hypothesized that obesity could also result in repressed gut adaptive immunity. Using small intestinal intraepithelial lymphocytes (IEL) as a readout, we found that in non-inflammatory bowel disease (IBD) subjects, high body mass index correlated with reduced IEL density. We recapitulated this in wild type (WT) mice fed with WD. A 4-week WD consumption was able to reduce IEL but not splenic, blood, or bone marrow lymphocytes, and the effect was reversible after another 2 weeks of standard diet (SD) washout. Importantly, WD-associated IEL reduction was not dependent on the presence of gut microbiota, as WD-fed germ-free mice also showed IEL reduction. We further found that WD-mediated Farnesoid X Receptor (FXR) activation in the gut triggered IEL reduction, and this was partially mediated by intestinal phagocytes. Activated FXR signaling stimulated phagocytes to secrete type I IFN, and inhibition of either FXR or type I IFN signaling within the phagocytes prevented WD-mediated IEL loss. Therefore, WD consumption represses both innate and adaptive immunity in the gut. These findings have significant clinical implications in the understanding of how diet modulates mucosal immunity.

The changing metabolic landscape of bile acids - keys to metabolism and immune regulation

Bile acids regulate nutrient absorption and mitochondrial function, they establish and maintain gut microbial community composition and mediate inflammation, and they serve as signalling molecules that regulate appetite and energy homeostasis. The observation that there are hundreds of bile acids, especially many amidated bile acids, necessitates a revision of many of the classical descriptions of bile acids and bile acid enzyme functions. For example, bile salt hydrolases also have transferase activity. There are now hundreds of known modifications to bile acids and thousands of bile acid-associated genes, especially when including the microbiome, distributed throughout the human body (for example, there are >2,400 bile salt hydrolases alone). The fact that so much of our genetic and small-molecule repertoire, in both amount and diversity, is dedicated to bile acid function highlights the centrality of bile acids as key regulators of metabolism and immune homeostasis, which is, in large part, communicated via the gut microbiome.

Metabolome-microbiome insights into therapeutic impact of 8-O-acetylharpagide against breast cancer in a murine model

Iridoid glycosides extract, which is the main active extract of Ajuga decumbens Thunb, has been proved to have anti-breast cancer activity in previous studies. However, it is still unknown whether 8-O-acetylharpagide, a main active compound in the extract, has anti-breast cancer activity. In this study, 4 T1 breast cancer mice model was first successfully established. Then the anti-breast cancer effect of 8-O-acetylharpagide was systematically investigated. Feces were collected for metabolomics and 16S rRNA analysis to assess the potential mechanism. The results showed that 8-O-acetylharpagide was effective in reducing 4 T1 mouse tumor volume and weight compared with the model group. Metabolome analysis revealed 12 potential metabolite biomarkers in feces, mainly involved in primary bile acid biosynthesis and arachidonic acid metabolism. The 16S rRNA sequencing results demonstrated that 8-O-acetylharpagide modulated the abundance of the intestinal flora in 4 T1 mice. Spearman correlation analysis showed that calcitriol and prostaglandin G2 strongly correlated with Akkermansia, Firmicutes and Muribaculum. Overall, the active compound 8-O-acetylharpagide could inhibit significantly breast cancer growth in 4 T1 breast cancer model mice. The mechanism of the anti-breast cancer effect of 8-O-acetylharpagide may be related to the regulation of primary bile acid biosynthesis and arachidonic acid metabolism and modulation of the abundance of Akkermansia and Firmicutes.

Gastrodin alleviates the deterioration of depressive-like behavior and glucolipid metabolism promoted by chronic stress in type 2 diabetic mice

The growing burden of psychological stress among diabetes patients has contributed to a rising incidence of depression within this population. It is of significant importance to conduct research on the impact of stress on diabetes patients and to explore potential pharmacological interventions to counteract the stress-induced exacerbation of their condition. Gastrodin is a low molecular weight bioactive compound extracted from the rhizome of Gastrodiae elata Blume, and it may be a preventive strategy for diabetes and a novel treatment for depression symptoms. However, its relevant pharmacological mechanisms for protecting against the impacts of psychological stress in diabetic patients are unclear. In this study, we performed 5 weeks CUMS intervention and simultaneously administered gastrodin (140 mg/kg, once daily) on T2DM mice, to investigate the potential protective effects of gastrodin. The protective effect of gastrodin was evaluated by behavioral tests, biochemical analysis, histopathological examination, RT-qPCR and gut microbiota analysis. We found that the depressive-like behavior and glucolipid metabolism could be deteriorated by chronic stress in type 2 diabetic mice, while gastrodin showed a protective effect against these exacerbations by regulating HPA hormones, activating FXR and Cyp7a1, reducing inflammatory and oxidative stress responses, and regulating ileal gut microbiota abundance. Gastrodin might be a potential therapeutic agent for mitigating the deterioration of diabetes conditions due to chronic stress.

Tomato Pectin Ameliorated Hepatic Steatosis in High-Fat-Diet Mice by Modulating Gut Microbiota and Bile Acid Metabolism

Nonalcoholic fatty liver disease (NAFLD) is a worldwide public health issue. Changes in the gut microbiota structure and composition are closely related to host pathophysiology processes. Pectin is associated with several beneficial health effects. In the present study, we aimed at investigating the effect of tomato pectin (TP) on hepatic steatosis and exploring the underlying mechanisms by focusing on the regulation of the gut microbiota-bile acid axis. Our results showed that TP attenuated high-fat diet (HFD)-induced liver steatosis and inflammation. TP administration increased the diversity of gut microbiota, enhancing the abundance of beneficial bacteria and suppressing the abundance of harmful or conditional pathogenic bacteria. Further antibiotic-caused microbiome depletion confirmed that the anti-NAFLD activities of TP were dependent on the regulation of gut microbiota. Besides, TP intervention affected feces bile acid metabolism and caused significant changes in functional conjugated bile acids, which in turn inhibited the ileum FXR/FGF15 signaling, leading to stimulation of the hepatic bile acid (BA) production. Furthermore, TP treatment accelerated BA excretion, promoted BA transportation, inhibited BA reabsorption, and facilitated cholesterol efflux to relieve HFD-induced hyperlipidemia. These findings provide a potential dietary intervention strategy for TP against NAFLD via modulation of cross-talk between BAs and gut bacteria.

Teduglutide improves liver chemistries in short bowel syndrome-associated intestinal failure: Post hoc analysis

BACKGROUND

Chronic hepatic complications are common in patients with short bowel syndrome-associated intestinal failure (SBS-IF). Teduglutide, a glucagon-like peptide-2 analogue, demonstrated efficacy in reducing parenteral nutrition and/or intravenous fluid dependence among patients with SBS-IF in phase 3 clinical studies.

METHODS

This was a post hoc analysis of pooled data from two separate randomized, double-blind, placebo-controlled, multinational phase 3 clinical studies. Adult patients with SBS-IF with parenteral nutrition and/or intravenous fluid dependence without liver disease at baseline were randomized to treatment with the glucagon-like peptide-2 analogue teduglutide (0.05 or 0.10 mg/kg/day) or placebo subcutaneously once daily for 24 weeks. Mixed-effects models assessed the baseline predictors of change in liver chemistries.

RESULTS

Between baseline and week 24, teduglutide treatment (n = 109) was associated with least squares mean reductions in aspartate aminotransferase (-7.51 IU/L; P = 0.014), alanine aminotransferase (-12.15 IU/L; P = 0.002), and bilirubin (-5.03 µmol/L [-0.057 mg/dl]; P < 0.001) compared with that of the placebo (n = 59). These values were independent of reductions in parenteral nutrition and/or intravenous fluid dependence.

CONCLUSION

Teduglutide treatment was associated with reductions in liver chemistries by week 24, which is beneficial for patients with SBS-IF beyond improvements in parenteral nutrition and/or intravenous fluid dependence. Future studies should examine how long-term teduglutide might mitigate the risk of liver disease in patients with SBS-IF.

Hepatic interoception in health and disease

The liver is a large organ with crucial functions in metabolism and immune defense, as well as blood homeostasis and detoxification, and it is clearly in bidirectional communication with the brain and rest of the body via both neural and humoral pathways. A host of neural sensory mechanisms have been proposed, but in contrast to the gut-brain axis, details for both the exact site and molecular signaling steps of their peripheral transduction mechanisms are generally lacking. Similarly, knowledge about function-specific sensory and motor components of both vagal and spinal access pathways to the hepatic parenchyma is missing. Lack of progress largely owes to controversies regarding selectivity of vagal access pathways and extent of hepatocyte innervation. In contrast, there is considerable evidence for glucose sensors in the wall of the hepatic portal vein and their importance for glucose handling by the liver and the brain and the systemic response to hypoglycemia. As liver diseases are on the rise globally, and there are intriguing associations between liver diseases and mental illnesses, it will be important to further dissect and identify both neural and humoral pathways that mediate hepatocyte-specific signals to relevant brain areas. The question of whether and how sensations from the liver contribute to interoceptive self-awareness has not yet been explored.

Trimethylamine N-oxide ameliorates hepatic damage including reduction of hepatic bile acids and cholesterol in Fxr-null mice

There are conflicting animal experiments on the effect of trimethylamine N-oxide (TMAO), the dietary metabolite, on non-alcoholic fatty liver disease (NAFLD). This study aims to determine the effect of TMAO on NAFLD. A diet containing 0.3% TMAO was fed to farnesoid X receptor (Fxr)-null mice, a model of NAFLD, for 13 weeks. Fxr-null mice fed TMAO showed significant reductions in liver damage markers but not wild-type mice. Hepatic bile acid and cholesterol levels were significantly decreased, and triacylglycerol levels tended to decrease in TMAO-fed Fxr-null mice. Changes in mRNA levels of hepatic bile acid and cholesterol transporters and synthetic enzymes were observed, which could explain the decreased hepatic bile acid and cholesterol levels in Fxr-null mice given the TMAO diet but not in the wild-type mice. These results suggest that TMAO intake ameliorates liver damage in Fxr-null mice, further altering bile acid/cholesterol metabolism in an FXR-independent manner.

An integrated analysis of bile acid metabolism in humans with severe obesity

BACKGROUND AND AIMS

Bile acids (BA) are vital regulators of metabolism. BAs are AQ6 secreted in the small intestine, reabsorbed, and transported back to the liver, where they can modulate metabolic functions. There is a paucity of data regarding the portal BA composition in humans. This study aimed to address this knowledge gap by investigating portal BA composition and the relation with peripheral and fecal BA dynamics in conjunction with the gut microbiome.

APPROACH AND RESULTS

Thirty-three individuals from the BARIA cohort were included. Portal plasma, peripheral plasma, and feces were collected. BA and C4 levels were measured employing mass spectrometry. FGF19 was measured using ELISA. Gut microbiota composition was determined through metagenomics analysis on stool samples. Considerable diversity in the portal BA composition was observed. The majority (n = 26) of individuals had a 9-fold higher portal than peripheral BA concentration. In contrast, 8 individuals showed lower portal BA concentration compared with peripheral and had higher levels of unconjugated and secondary BA in this compartment, suggesting more distal origin. The altered portal BA profile was associated with altered gut microbiota composition. In particular, taxa within Bacteroides were reduced in abundance in the feces of these individuals.

CONCLUSIONS

Characterization of the portal BA composition in relation to peripheral and fecal BA increased insight into the dynamics of BA metabolism in individuals with obesity. Peripheral BA composition was much more diverse due to microbial metabolism. About 24% of the portal samples was surprisingly low in total BA; the underlying mechanism requires further exploration.

Association of gastrointestinal microbiome and obesity with gestational diabetes mellitus-an updated globally based review of the high-quality literatures

OBJECTIVES

The purpose of this review is to investigate the relationship between gastrointestinal microbiome, obesity, and gestational diabetes mellitus (GDM) in an objective manner.

METHODS

We conducted a thorough and comprehensive search of the English language literatures published in PubMed, Web of Science, and the Cochrane Library from the establishment of the library until 12 December 2023. Our search strategy included both keywords and free words searches, and we strictly applied inclusion and exclusion criteria. Meta-analyses and systematic reviews were prepared.

RESULTS

Six high-quality literature sources were identified for meta-analysis. However, after detailed study and analysis, a certain degree of heterogeneity was found, and the credibility of the combined analysis results was limited. Therefore, descriptive analyses were conducted. The dysbiosis of intestinal microbiome, specifically the ratio of Firmicutes/Bacteroides, is a significant factor in the development of metabolic diseases such as obesity and gestational diabetes. Patients with intestinal dysbiosis and obesity are at a higher risk of developing GDM.

CONCLUSIONS

During pregnancy, gastrointestinal microbiome disorders and obesity may contribute to the development of GDM, with all three factors influencing each other. This finding could aid in the diagnosis and management of patients with GDM through further research on their gastrointestinal microbiome.

Bile acids and coronavirus disease 2019

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been significantly alleviated. However, long-term health effects and prevention strategy remain unresolved. Thus, it is essential to explore the pathophysiological mechanisms and intervention for SARS-CoV-2 infection. Emerging research indicates a link between COVID-19 and bile acids, traditionally known for facilitating dietary fat absorption. The bile acid ursodeoxycholic acid potentially protects against SARS-CoV-2 infection by inhibiting the farnesoid X receptor, a bile acid nuclear receptor. The activation of G-protein-coupled bile acid receptor, another membrane receptor for bile acids, has also been found to regulate the expression of angiotensin-converting enzyme 2, the receptor through which the virus enters human cells. Here, we review the latest basic and clinical evidence linking bile acids to SARS-CoV-2, and reveal their complicated pathophysiological mechanisms.

Effects of subchronic and mild social defeat stress on the intestinal microbiota and fecal bile acid composition in mice

The gut microbiota plays a crucial role in both the pathogenesis and alleviation of host depression by modulating the brain-gut axis. We have developed a murine model of human depression called the subchronic and mild social defeat stress (sCSDS) model, which impacts not only behavior but also the host gut microbiota and gut metabolites, including bile acids. In this study, we utilized liquid chromatography/mass spectrometry (LC/MS) to explore the effects of sCSDS on the mouse fecal bile acid profile. sCSDS mice exhibited significantly elevated levels of deoxycholic acid (DCA) and lithocholic acid (LCA) in fecal extracts, leading to a notable increase in total bile acids and 7α-dehydroxylated secondary bile acids. Consequently, a noteworthy negative correlation was identified between the abundances of DCA and LCA and the social interaction score, an indicator of susceptibility in stressed mice. Furthermore, analysis of the colonic microbiome unveiled a negative correlation between the abundance of CDCA and Turicibacter. Additionally, DCA and LCA exhibited positive correlations with Oscillospiraceae and Lachnospiraceae but negative correlations with the Eubacterium coprostanoligenes group. These findings suggest that sCSDS impacts the bidirectional interaction between the gut microbiota and bile acids and is associated with reduced social interaction, a behavioral indicator of susceptibility in stressed mice.

A two-sample bidirectional Mendelian randomization analysis investigates associations between gut microbiota and type 2 diabetes mellitus

Objective

This study sought to elucidate the causal association between gut microbiota (GM) composition and type 2 diabetes mellitus (T2DM) through a comprehensive two-sample bidirectional Mendelian randomization analysis.

Method

T2DM data were sourced from the IEU OpenGWAS Project database, complemented by 211 gut microbiota (GM) datasets from the MiBioGen Federation. The primary analytical approach employed was inverse variance weighted (IVW), supplemented by MR-Egger regression and weighted median (WME) methods to investigate their potential interplay. Results were assessed using odds ratios (OR) and 95% confidence intervals (CI). The robustness and reliability of the findings were confirmed through leave-one-out analysis, heterogeneity testing, and assessment of horizontal pleiotropy. Furthermore, we explored the potential mediating role of metabolites in the pathway linking GM to T2DM.

Result

A set of 11 Single Nucleotide Polymorphisms (SNPs) linked to GM were identified as instrumental variables (IVs). The IVW analysis revealed that increased abundance of the genus Actinomyces, genus Bilophila, genus Lachnoclostridium, genus Ruminococcus gnavus group, and genus Streptococcus corresponded to a heightened risk of T2DM. Conversely, higher levels of genus Eubacterium oxidoreducens group, genus Oscillospira, genus Ruminococcaceae UCG003, genus Ruminococcaceae UCG010, and genus Sellimonas were associated with a reduced risk of T2DM. However, following false discovery rate (FDR) correction, only the abundance of genus Lachnoclostridium retained a significant positive correlation with T2DM risk (OR = 1.22, q value = 0.09), while the other ten GM showed suggestive associations with T2DM. Reverse MR analysis did not reveal any causal relationship between T2DM and the increased risk associated with the identified GM. Additionally, metabolites did not exhibit mediating effects in this context.

Conclusion

This study effectively pinpointed specific GM associated with T2DM, potentially paving the way for novel biomarkers in the prevention and treatment of this condition. The findings suggested that probiotics could emerge as a promising avenue for managing T2DM in the future. Furthermore, the analysis indicated that metabolites do not appear to act as mediators in the pathway from GM to T2DM.

Pro-Inflammatory Food, Gut Microbiota, and Cardiovascular and Pancreatic Diseases

Recent studies have shown that a pro-inflammatory diet and dysbiosis, especially a high level of trimethylamine-N-oxide (TMAO), are associated with various adverse health conditions. Cardiovascular diseases and pancreatic diseases are two major morbidities in the modern world. Through this narrative review, we aimed to summarize the association between a pro-inflammatory diet, gut microbiota, and cardiovascular and pancreatic diseases, along with their underlying mechanisms. Our review revealed that TMAO is associated with the development of cardiovascular diseases by promoting platelet aggregation, atherosclerotic plaque formation, and vascular inflammation. TMAO is also associated with the development of acute pancreatitis. The pro-inflammatory diet is associated with an increased risk of pancreatic cancer and cardiovascular diseases through mechanisms that include increasing TMAO levels, activating the lipopolysaccharides cascade, and the direct pro-inflammatory effect of certain nutrients. Meanwhile, an anti-inflammatory diet decreases the risk of cardiovascular diseases and pancreatic cancer.

Obeticholic acid protects against lithocholic acid-induced exogenous cell apoptosis during cholestatic liver injury

AIMS

Lithocholic acid (LCA)-induced cholestasis was accompanied by the occurrence of apoptosis, which indicated that anti-apoptosis was a therapeutic strategy for primary biliary cholangitis (PBC). As an agonist of (Farnesoid X receptor) FXR, we supposed that the hepatoprotection of Obeticholic acid (OCA) against cholestatic liver injury is related to anti-apoptosis beside of the bile acids (BAs) regulation. Herein, we explored the non-metabolic regulating mechanism of OCA for resisting LCA-induced cholestatic liver injury via anti-apoptosis.

MAIN METHODS

LCA-induced cholestatic liver injury mice were pretreated with OCA to evaluate its hepatoprotective effect and mechanism. Biochemical and pathological indicators were used to detect the protective effect of OCA on LCA-induced cholestatic liver injury. The bile acids (BAs) profile in serum was detected by LC-MS/MS. Hepatocyte BAs metabolism, apoptosis and inflammation related genes and proteins alteration were investigated by biochemical determination.

KEY FINDINGS

OCA improved LCA-induced cholestasis and hepatic apoptosis in mice. The BA profile in serum was changed by OCA mainly manifested as a reduction of taurine-conjugated bile acids, which was due to the upregulation of FXR-related bile acid efflux transporters bile salt export pump (BSEP), multi-drug resistant associated protein 2 (MRP2), MRP3 and multi-drug resistance 3 (MDR3). Apoptosis related proteins cleaved caspase-3, cleaved caspase-8 and cleaved PARP were obviously reduced after OCA treatment.

SIGNIFICANCE

OCA improved LCA-induced cholestatic liver injury via FXR-induced exogenous cell apoptosis, which will provide new evidence for the application of OCA to ameliorate PBC in clinical.

Bacteroides fragilis alleviates necrotizing enterocolitis through restoring bile acid metabolism balance using bile salt hydrolase and inhibiting FXR-NLRP3 signaling pathway

Necrotizing enterocolitis (NEC) is a leading cause of morbidity and mortality in premature infants with no specific treatments available. We aimed to identify the molecular mechanisms underlying NEC and investigate the therapeutic effects of Bacteroides fragilis on NEC. Clinical samples of infant feces, bile acid-targeted metabolomics, pathological staining, bioinformatics analysis, NEC rat model, and co-immunoprecipitation were used to explore the pathogenesis of NEC. Taxonomic characterization of the bile salt hydrolase (bsh) gene, enzyme activity assays, 16S rRNA sequencing, and organoids were used to explore the therapeutic effects of B. fragilis on NEC-related intestinal damage. Clinical samples, NEC rat models, and in vitro experiments revealed that total bile acid increased in the blood but decreased in feces. Moreover, the levels of FXR and other bile acid metabolism-related genes were abnormal, resulting in disordered bile acid metabolism in NEC. Taurochenodeoxycholic acid accelerated NEC pathogenesis and taurodeoxycholate alleviated NEC. B. fragilis displayed bsh genes and enzyme activity and alleviated intestinal damage by restoring gut microbiota dysbiosis and bile acid metabolism abnormalities by inhibiting the FXR-NLRP3 signaling pathway. Our results provide valuable insights into the therapeutic role of B. fragilis in NEC. Administering B. fragilis may substantially alleviate intestinal damage in NEC.

Maternal exposure to 4-vinylcyclohexene diepoxide during pregnancy leads to disorder of gut microbiota and bile acid metabolism in offspring

Our previous study reveals that maternal exposure to 4-vinylcyclohexene diepoxide (VCD) during pregnancy causes insufficient ovarian follicle reserve and decreased fertility in offspring. The present study aims to further explore the reasons for the significant decline of fecundity in mice caused by VCD, and to clarify the changes of gut microbiota and microbial metabolites in F1 mice. The ovarian metabolomics, gut microbiota and microbial metabolites were analyzed. The results of ovarian metabolomics analysis showed that maternal VCD exposure during pregnancy significantly reduced the concentration of carnitine in the ovaries of F1 mice, while supplementation with carnitine (isovalerylcarnitine and valerylcarnitine) significantly increased the number of ovulation. The results of 16 S rDNA-seq and microbial metabolites analysis showed that maternal VCD exposure during pregnancy caused disordered gut microbiota, increased abundance of Parabacteroides and Flexispira bacteria that are involved in secondary bile acid synthesis. The concentrations of NorDCA, LCA-3S, DCA and other secondary bile acids increased significantly. Our results indicate that maternal exposure to VCD during pregnancy leads to disorder in gut microbiota and bile acid metabolism in F1 mice, accompanying with decreased ovarian function, providing further evidence that maternal exposure to VCD during pregnancy has intergenerational deleterious effects on offspring.

Physical exercise plays a role in rebalancing the bile acids of enterohepatic axis in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is considered as one of the most common diseases of lipid metabolism disorders, which is closely related to bile acids disorders and gut microbiota disorders. Bile acids are synthesized from cholesterol in the liver, and processed by gut microbiota in intestinal tract, and participate in metabolic regulation through the enterohepatic circulation. Bile acids not only promote the consumption and absorption of intestinal fat but also play an important role in biological metabolic signaling network, affecting fat metabolism and glucose metabolism. Studies have demonstrated that exercise plays an important role in regulating the composition and function of bile acid pool in enterohepatic axis, which maintains the homeostasis of the enterohepatic circulation and the health of the host gut microbiota. Exercise has been recommended by several health guidelines as the first-line intervention for patients with NAFLD. Can exercise alter bile acids through the microbiota in the enterohepatic axis? If so, regulating bile acids through exercise may be a promising treatment strategy for NAFLD. However, the specific mechanisms underlying this potential connection are largely unknown. Therefore, in this review, we tried to review the relationship among NAFLD, physical exercise, bile acids, and gut microbiota through the existing data and literature, highlighting the role of physical exercise in rebalancing bile acid and microbial dysbiosis.

MAPL loss dysregulates bile and liver metabolism in mice

Mitochondrial and peroxisomal anchored protein ligase (MAPL) is a dual ubiquitin and small ubiquitin-like modifier (SUMO) ligase with roles in mitochondrial quality control, cell death and inflammation in cultured cells. Here, we show that MAPL function in the organismal context converges on metabolic control, as knockout mice are viable, insulin-sensitive, and protected from diet-induced obesity. MAPL loss leads to liver-specific activation of the integrated stress response, inducing secretion of stress hormone FGF21. MAPL knockout mice develop fully penetrant spontaneous hepatocellular carcinoma. Mechanistically, the peroxisomal bile acid transporter ABCD3 is a primary MAPL interacting partner and SUMOylated in a MAPL-dependent manner. MAPL knockout leads to increased bile acid production coupled with defective regulatory feedback in liver in vivo and in isolated primary hepatocytes, suggesting cell-autonomous function. Together, our findings establish MAPL function as a regulator of bile acid synthesis whose loss leads to the disruption of bile acid feedback mechanisms. The consequences of MAPL loss in liver, along with evidence of tumor suppression through regulation of cell survival pathways, ultimately lead to hepatocellular carcinogenesis.

Profile of the bile acid FXR-FGF15 pathway in the glucolipid metabolism disorder of diabetic mice suffering from chronic stress

Background

Imbalances in bile acid (BA) synthesis and metabolism are involved in the onset of diabetes and depression in humans and rodents. However, the role of BAs and the farnesoid X receptor (FXR)/fibroblast growth factor (FGF) 15 signaling pathway in the development of diabetes and depression is still largely unknown. Therefore, we investigated the potential molecular mechanisms of BAs that may be associated with glucolipid metabolism disorders in diabetic mice subjected to chronic stress.

Methods

The type 2 diabetes mellitus (T2DM) mouse model was induced by feeding mice a high-fat diet and administering an intraperitoneal injection of streptozotocin (STZ). The chronic unpredictable mild stress (CUMS) procedure was performed by introducing a series of mild stressors. Forty mice were randomly divided into the regular chow feeding group and the high-fat diet feeding group. After two weeks of feeding, the mice were randomly divided into four groups: the Control group, CUMS group, T2DM group, and T2DM+CUMS group. The T2DM group and T2DM+CUMS group received an intraperitoneal injection of STZ to induce the T2DM model. The CUMS and T2DM+CUMS groups were exposed to CUMS to induce depressive-like phenotypes. Blood and tissue samples were obtained for pertinent analysis and detection.

Results

Compared with the T2DM mice, T2DM+CUMS mice had higher blood glucose and lipid levels, insulin resistance, inflammation of the liver and pancreas, impaired liver function, and increased total bile acids. These changes were accompanied by attenuated FXR signaling. Chronic stress was found to attenuate FXR expression and its downstream target, FGF15, in the ileum when compared with the T2DM group.

Conclusion

FXR may play a role in the diabetic disorder of glucolipid metabolism when aggravated by chronic stress. FXR and its downstream target, FGF15, may be therapeutic targets for treating comorbid T2DM and depression.

Effects and possible mechanisms of intermittent fasting on health and disease: a narrative review

The imbalance between energy intake and expenditure in an environment of continuous food availability can lead to metabolic disturbances in the body and increase the risk of obesity and a range of chronic noncommunicable diseases. Intermittent fasting (IF) is one of the most popular nonpharmacological interventions to combat obesity and chronic noncommunicable diseases. The 3 most widely studied IF regimens are alternate-day fasting, time-restricted feeding, and the 5:2 diet. In rodents, IF helps optimize energy metabolism, prevent obesity, promote brain health, improve immune and reproductive function, and delay aging. In humans, IF's benefits are relevant for the aging global population and for increasing human life expectancy. However, the optimal model of IF remains unclear. In this review, the possible mechanisms of IF are summarized and its possible drawbacks are discussed on the basis of the results of existing research, which provide a new idea for nonpharmaceutical dietary intervention of chronic noncommunicable diseases.

The interaction of bile acids and gut inflammation influences the pathogenesis of inflammatory bowel disease

Bile acids (BA) are amphipathic molecules originating from cholesterol in the liver and from microbiota-driven biotransformation in the colon. In the gut, BA play a key role in fat digestion and absorption and act as potent signaling molecules on the nuclear farnesoid X receptor (FXR) and membrane-associated G protein-coupled BA receptor-1 (GPBAR-1). BA are, therefore, involved in the maintenance of gut barrier integrity, gene expression, metabolic homeostasis, and microbiota profile and function. Disturbed BA homeostasis can activate pro-inflammatory pathways in the gut, while inflammatory bowel diseases (IBD) can induce gut dysbiosis and qualitative and/or quantitative changes of the BA pool. These factors contribute to impaired repair capacity of the mucosal barrier, due to chronic inflammation. A better understanding of BA-dependent mechanisms paves the way to innovative therapeutic tools by administering hydrophilic BA and FXR agonists and manipulating gut microbiota with probiotics and prebiotics. We discuss the translational value of pathophysiological and therapeutic evidence linking BA homeostasis to gut inflammation in IBD.

The potential mechanism of gut microbiota-microbial metabolites-mitochondrial axis in progression of diabetic kidney disease

Diabetic kidney disease (DKD), has become the main cause of end-stage renal disease (ESRD) worldwide. Lately, it has been shown that the onset and advancement of DKD are linked to imbalances of gut microbiota and the abnormal generation of microbial metabolites. Similarly, a body of recent evidence revealed that biological alterations of mitochondria ranging from mitochondrial dysfunction and morphology can also exert significant effects on the occurrence of DKD. Based on the prevailing theory of endosymbiosis, it is believed that human mitochondria originated from microorganisms and share comparable biological characteristics with the microbiota found in the gut. Recent research has shown a strong correlation between the gut microbiome and mitochondrial function in the occurrence and development of metabolic disorders. The gut microbiome's metabolites may play a vital role in this communication. However, the relationship between the gut microbiome and mitochondrial function in the development of DKD is not yet fully understood, and the role of microbial metabolites is still unclear. Recent studies are highlighted in this review to examine the possible mechanism of the gut microbiota-microbial metabolites-mitochondrial axis in the progression of DKD and the new therapeutic approaches for preventing or reducing DKD based on this biological axis in the future.

Beneficial effects of silibinin on serum lipids, bile acids, and gut microbiota in methionine-choline-deficient diet-induced mice

Background and purpose

Silibinin (SIL) is a flavonoid lignin isolated from the fruit and seeds of silybum marianum that exhibits good therapeutic potential for NASH. However, the effects of SIL on serum lipids, bile acids (BAs), and gut microbiota (GM) in NASH mice remain unknown. The present work aimed to explore the beneficial effects of SIL supplementation on serum lipids, bile acids, and gut microbiota in MCD mice.

Experimental approach

After male C57BL/6 mice were fed with a methionine-choline deficient (MCD) diet and simultaneously gavaged with SIL (20 mg/kg. d) for 8 weeks, the pathological changes of liver tissue were observed by oil red O, haematoxylin-eosin, and Masson tricolor staining; the levels of serum AST and ALT, and liver TG and MDA were detected by assay kits; metabonomics and 16S rDNA sequencing were used to analyze the composition of serum lipids and BAs and the abundance of GM; and the mRNA expression levels of hepatic genes related to BAs homeostasis were detected by RT-qPCR.

Results

The results indicated that SIL treatment decreased the levels of 26 lipids (including four arachidonic acids, seven FFAs, 12 acyl carnitines, and three GPs) and two BAs (23-DCA, GLCA), while Dubosiella increased the levels of 10 lipids (including TxB3, PG16:0_18:1, Cer t18:0/24:0 and 7 TGs), five BAs (β-MCA, α-MCA, UDCA, 3-oxo-DCA and HCA), and two GMs (Verrucomicrobiota and Akkermansiaceae) of MCD mice, but had no significant effect on the mRNA expression of CYP7A1, CYP27A1, Bsep, Mrp2, Ntcp, or Oatp1b2. Therefore, influencing GM composition and then regulating the levels of serum lipids and BAs through enterohepatic axis should be an important mechanism of SIL-induced alleviative effect on MCD mice. More importantly, we found that SIL had a good coordination in regulating the abundance of GM and the contents of serum lipids and BAs in MCD mice, that is, when the abundance of probiotics was up-regulated, the content of beneficial unsaturated fatty acids in serum was up-regulated, while the serum levels of harmful lipids and BAs were down-regulated.

Conclusion

The alleviating effect of SIL on NASH may be closely related to the correction of intestinal bacteria disorder, serum bile acid, and lipid metabolic disturbance in mice.

Contribution of the microbiome for better phenotyping of people living with obesity

Obesity has reached epidemic proportion worldwide and in all ages. Available evidence points to a multifactorial pathogenesis involving gene predisposition and environmental factors. Gut microbiota plays a critical role as a major interface between external factors, i.e., diet, lifestyle, toxic chemicals, and internal mechanisms regulating energy and metabolic homeostasis, fat production and storage. A shift in microbiota composition is linked with overweight and obesity, with pathogenic mechanisms involving bacterial products and metabolites (mainly endocannabinoid-related mediators, short-chain fatty acids, bile acids, catabolites of tryptophan, lipopolysaccharides) and subsequent alterations in gut barrier, altered metabolic homeostasis, insulin resistance and chronic, low-grade inflammation. Although animal studies point to the links between an "obesogenic" microbiota and the development of different obesity phenotypes, the translational value of these results in humans is still limited by the heterogeneity among studies, the high variation of gut microbiota over time and the lack of robust longitudinal studies adequately considering inter-individual confounders. Nevertheless, available evidence underscores the existence of several genera predisposing to obesity or, conversely, to lean and metabolically health phenotype (e.g., Akkermansia muciniphila, species from genera Faecalibacterium, Alistipes, Roseburia). Further longitudinal studies using metagenomics, transcriptomics, proteomics, and metabolomics with exact characterization of confounders are needed in this field. Results must confirm that distinct genera and specific microbial-derived metabolites represent effective and precision interventions against overweight and obesity in the long-term.

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.

The Gut Microbial Bile Acid Modulation and Its Relevance to Digestive Health and Diseases

The human gut microbiome has been linked to numerous digestive disorders, but its metabolic products have been much less well characterized, in part due to the expense of untargeted metabolomics and lack of ability to process the data. In this review, we focused on the rapidly expanding information about the bile acid repertoire produced by the gut microbiome, including the impacts of bile acids on a wide range of host physiological processes and diseases, and discussed the role of short-chain fatty acids and other important gut microbiome-derived metabolites. Of particular note is the action of gut microbiome-derived metabolites throughout the body, which impact processes ranging from obesity to aging to disorders traditionally thought of as diseases of the nervous system, but that are now recognized as being strongly influenced by the gut microbiome and the metabolites it produces. We also highlighted the emerging role for modifying the gut microbiome to improve health or to treat disease, including the "engineered native bacteria'' approach that takes bacterial strains from a patient, modifies them to alter metabolism, and reintroduces them. Taken together, study of the metabolites derived from the gut microbiome provided insights into a wide range of physiological and pathophysiological processes, and has substantial potential for new approaches to diagnostics and therapeutics of disease of, or involving, the gastrointestinal tract.

Alterations in the gut microbiota and serum metabolomics of spontaneous cholestasis caused by loss of FXR signal in mice

Background: Farnesoid X receptor (FXR) is a key metabolic target of bile acids (BAs) and is also a target for drugs against several liver diseases. However, the contribution of FXR in the pathogenesis of cholestasis is still not fully understood. The purpose of this study is to provide a comprehensive insight into the metabolic properties of FXR-involved cholestasis in mice. Materials and methods: In this study, an alpha-naphthylisothiocyanate (ANIT)-induced cholestasis mouse model and FXR^-/- mice were established to investigate the effect of FXR on cholestasis. The effect of FXR on liver and ileal pathology was evaluated. Simultaneously, Untargeted metabolomics combined with 16s rRNA gene sequencing analysis was applied to reveal the involvement of FXR in the pathogenesis of cholestasis. Results: The results showed that ANIT (75 mg/kg) induced marked cholestasis in WT and FXR -/- mice. It is noteworthy that FXR^-/- mice developed spontaneous cholestasis. Compared with WT mice, significant liver and ileal tissue damage were found. In addition, 16s rRNA gene sequencing analysis revealed gut microbiota dysbiosis in FXR-/- mice and ANIT-induced cholestasis mice. Differential biomarkers associated with the pathogenesis of cholestasis caused by FXR knockout were screened using untargeted metabolomics. Notably, Lactobacillus_ johnsonii_FI9785 has a high correlation with the differential biomarkers associated with the pathogenesis and progression of cholestasis caused by FXR knockout. Conclusion: Our results implied that the disorder of the intestinal flora caused by FXR knockout can also interfere with the metabolism. This study provides novel insights into the FXR-related mechanisms of cholestasis.

Role of herbal medicine and gut microbiota in the prevention and treatment of obesity

ETHNOPHARMACOLOGICAL RELEVANCE

Obesity is a common metabolic dysfunction disease, which is highly correlated with the homeostasis of gut microbiota (GM). The dysregulation of GM on energy metabolism, immune response, insulin resistance and endogenous metabolites (e.g., short chain fatty acids and secondary bile acids) can affect the occurrence and development of obesity. Herbal medicine (HM) has particular advantages and definite therapeutic effects in the prevention and treatment of obesity, but its underlying mechanism is not fully clear.

AIM OF THE STUDY

In this review, the representative basic and clinical anti-obesity studies associated with the homeostasis of GM regulated by HM including active components, single herb and herbal formulae were summarized and discussed. We aim to provide a state of art reference for the mechanism research of HM in treating obesity and the further development of new anti-obesity drugs.

MATERIALS AND METHODS

The relevant information was collected by searching keywords (obesity, herbal medicine, prescriptions, mechanism, GM, short chain fatty acids, etc.) from scientific databases (CNKI, PubMed, SpringerLink, Web of Science, SciFinder, etc.).

RESULTS

GM dysbiosis did occur in obese patients and mice, whiles the intervention of GM could ameliorate the condition of obesity. HM (e.g., berberine, Ephedra sinica, Rehjnannia glutinosa, and Buzhong Yiqi prescription) has been proved to possess a certain regulation on GM and an explicit effect on obesity, but the exact mechanism of HM in improving obesity by regulating GM remains superficial.

CONCLUSION

GM is involved in HM against obesity, and GM can be a novel therapeutic target for treating obesity.

The gut microbiome: a core regulator of metabolism

The human body is inhabited by numerous bacteria, fungi, and viruses, and each part has a unique microbial community structure. The gastrointestinal tract harbors approximately 100 trillion strains comprising more than 1000 bacterial species that maintain symbiotic relationships with the host. The gut microbiota consists mainly of the phyla Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. Of these, Firmicutes and Bacteroidetes constitute 70-90% of the total abundance. Gut microbiota utilize nutrients ingested by the host, interact with other bacterial species, and help maintain healthy homeostasis in the host. In recent years, it has become increasingly clear that a breakdown of the microbial structure and its functions, known as dysbiosis, is associated with the development of allergies, autoimmune diseases, cancers, and arteriosclerosis, among others. Metabolic diseases, such as obesity and diabetes, also have a causal relationship with dysbiosis. The present review provides a brief overview of the general roles of the gut microbiota and their relationship with metabolic disorders.

Metabolomic profiling for the preventive effects of dietary grape pomace against colorectal cancer

Colorectal cancer (CRC) is one of the most common and deadly cancers worldwide. Grape pomace (GP) is a rich source of bioactive compounds with anti-inflammatory, and anticancer effects. We recently found that dietary GP had protective effects against CRC development in the azoxymethane (AOM)/dextran sulfate sodium (DSS) CRC mouse model through suppression of cell proliferation and modulation of DNA methylation. However, the underlying molecular mechanisms associated with changes in metabolites remain unexamined. This study profiled fecal metabolomic changes in a mouse CRC model in response to GP supplementation using gas chromatography-mass spectrometry (GC-MS) based metabolomic analysis. A total of 29 compounds showed significant changes due to GP supplementation, including bile acids, amino acids, fatty acids, phenols/flavonoids, glycerolipids, carbohydrates, organic acids, and others. The major changes in metabolites of feces include increased deoxycholic acid (DCA) and decreased amino acid content. Dietary GP upregulated the expression of farnesoid X receptor (FXR) downstream genes while decreasing fecal urease activity. DNA repair enzyme MutS Homolog 2 (MSH2) was upregulated by GP supplementation. Consistently, γ-H2AX, as a DNA damage marker, decreased in GP supplemented mice. Moreover, MDM2, a protein in the ataxia telangiectasia mutated (ATM) signaling, was decreased by GP supplementation. These data provided valuable metabolic clues for unraveling the protective effects of GP supplementation against CRC development.

Specificity Proteins (SP) and Krüppel-like Factors (KLF) in Liver Physiology and Pathology

The liver acts as a central hub that controls several essential physiological processes ranging from metabolism to detoxification of xenobiotics. At the cellular level, these pleiotropic functions are facilitated through transcriptional regulation in hepatocytes. Defects in hepatocyte function and its transcriptional regulatory mechanisms have a detrimental influence on liver function leading to the development of hepatic diseases. In recent years, increased intake of alcohol and western diet also resulted in a significantly increasing number of people predisposed to the incidence of hepatic diseases. Liver diseases constitute one of the serious contributors to global deaths, constituting the cause of approximately two million deaths worldwide. Understanding hepatocyte transcriptional mechanisms and gene regulation is essential to delineate pathophysiology during disease progression. The current review summarizes the contribution of a family of zinc finger family transcription factors, named specificity protein (SP) and Krüppel-like factors (KLF), in physiological hepatocyte functions, as well as how they are involved in the onset and development of hepatic diseases.

Natural Monoterpenes as Potential Therapeutic Agents against Atherosclerosis

Traditional herbal medicines based on natural products play a pivotal role in preventing and managing atherosclerotic diseases, which are among the leading causes of death globally. Monoterpenes are a large class of naturally occurring compounds commonly found in many aromatic and medicinal plants. Emerging evidence has shown that monoterpenes have many biological properties, including cardioprotective effects. Remarkably, an increasing number of studies have demonstrated the therapeutic potential of natural monoterpenes to protect against the pathogenesis of atherosclerosis. These findings shed light on developing novel effective antiatherogenic drugs from these compounds. Herein, we provide an overview of natural monoterpenes' effects on atherogenesis and the underlying mechanisms. Monoterpenes have pleiotropic and multitargeted pharmacological properties by interacting with various cell types and intracellular molecular pathways involved in atherogenesis. These properties confer remarkable advantages in managing atherosclerosis, which has been recognized as a multifaceted vascular disease. We also discuss limitations in the potential clinical application of monoterpenes as therapeutic agents against atherosclerosis. We propose perspectives to give new insights into future preclinical research and clinical practice regarding natural monoterpenes.

Fenofibrate Mitigates Hypertriglyceridemia in Nonalcoholic Steatohepatitis Patients Treated With Cilofexor/Firsocostat

BACKGROUND & AIMS

Patients with advanced fibrosis due to nonalcoholic steatohepatitis (NASH) are at high risk of morbidity and mortality. We previously found that a combination of the farnesoid X receptor agonist cilofexor (CILO) and the acetyl-CoA carboxylase inhibitor firsocostat (FIR) improved liver histology and biomarkers in NASH with advanced fibrosis but was associated with hypertriglyceridemia. We evaluated the safety and efficacy of icosapent ethyl (Vascepa) and fenofibrate to mitigate triglyceride elevations in patients with NASH treated with CILO and FIR.

METHODS

Patients with NASH with elevated triglycerides (≥150 and <500 mg/dL) were randomized to Vascepa 2 g twice daily (n = 33) or fenofibrate 145 mg daily (n = 33) for 2 weeks, followed by the addition of CILO 30 mg and FIR 20 mg daily for 6 weeks. Safety, lipids, and liver biochemistry were monitored.

RESULTS

All treatments were well-tolerated; most treatment-emergent adverse events were Grade 1 to 2 severity, and there were no discontinuations due to adverse events. At baseline, median (interquartile range [IQR]) triglycerides were similar in the Vascepa and fenofibrate groups (median, 177 [IQR, 154-205] vs 190 [IQR, 144-258] mg/dL, respectively). Median changes from baseline in triglycerides for Vascepa vs fenofibrate after 2 weeks of pretreatment were -12 mg/dL (IQR, -33 to 7 mg/dL; P = .09) vs -32 mg/dL (IQR, -76 to 6 mg/dL; P = .012) and at 6 weeks were +41 mg/dL (IQR, 16-103 mg/dL; P < .001) vs -2 mg/dL (IQR, -42 to 54 mg/dL; P = .92). In patients with baseline triglycerides <250 mg/dL, fenofibrate was more effective vs Vascepa in mitigating triglyceride increases after 6 weeks of combination treatment (+6 vs +39 mg/dL); similar trends were observed in patients with baseline triglycerides ≥250 mg/d (-61 vs +99 mg/dL).

CONCLUSIONS

In patients with NASH with hypertriglyceridemia treated with CILO and FIR, fenofibrate was safe and effectively mitigated increases in triglycerides associated with acetyl-CoA carboxylase inhibition.

CLINICALTRIALS

gov, Number: NCT02781584.

Extraction of Naringin from Pomelo and Its Therapeutic Potentials against Hyperlipidemia

Pomelo peel is a natural plant product with numerous pharmacological effects and is used in traditional Chinese medicine. In the present study, we extracted naringin from pomelo peel and aimed to decipher its therapeutic potential against hyperlipidemia. We used ultrasonic-assisted extraction to obtain naringin prior to identifying its structure, to evaluate its ability in binding sodium glycine cholate and sodium bovine cholate in vitro by simulating the gastrointestinal environment, so as to evaluate its blood lipid-lowering activity. The hyperlipidemia mouse model was established. Following the intragastric administration of naringin for 5 weeks, we measured the weight change, organ index, high-density lipoprotein cholesterol (HDL-C), serum total cholesterol (TC), serum triglycerides (TG), liver superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), low-density lipoprotein cholesterol (LDL-C) level, malondialdehyde (MDA), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) level of mice in the normal control and high-fat diet groups in addition to the high-, medium-, and low-dose naringin groups. The pathological changes in the liver were observed under a light microscope. The total RNA of the liver was extracted, and the mRNA expression level of lipid metabolism-related factors in mouse liver was detected via a fluorescence quantitative polymerase chain reaction (PCR). Naringin significantly (p < 0.01) reduced the body weight, organ index, serum TG, LDL-C, and TC levels of hyperlipidemic mice, but increased the serum HDL-C levels (p < 0.01). Furthermore, naringin increased GSH Px and SOD activity (p < 0.01), while decreasing MDA, ALT, and AST levels, as well as the liver index (p < 0.01). There was no statistically significant difference in the brain, heart, spleen, kidney, and other indicators (p > 0.05). A histopathological analysis of mouse liver showed that naringin could alleviate the degenerative damage of fatty liver cells in hyperlipidemic mice. Naringin could significantly (p < 0.01) reduce the expression of FAS and SREBP-1c mRNA, and simultaneously increase PPARα mRNA expression. This study shows that naringin has the strong effect of lowering lipids and protecting the liver in hyperlipidemic mice. Our findings underscore the anti-hyperlipidemia potential of naringin and increase the scientific understanding of its anti-hyperlipidemia effects, that may lead to its potential application as a dietary strategy for hyperlipidemia management in the future.

Recent Advances in the Digestive, Metabolic and Therapeutic Effects of Farnesoid X Receptor and Fibroblast Growth Factor 19: From Cholesterol to Bile Acid Signaling

Bile acids (BA) are amphiphilic molecules synthesized in the liver (primary BA) starting from cholesterol. In the small intestine, BA act as strong detergents for emulsification, solubilization and absorption of dietary fat, cholesterol, and lipid-soluble vitamins. Primary BA escaping the active ileal re-absorption undergo the microbiota-dependent biotransformation to secondary BA in the colon, and passive diffusion into the portal vein towards the liver. BA also act as signaling molecules able to play a systemic role in a variety of metabolic functions, mainly through the activation of nuclear and membrane-associated receptors in the intestine, gallbladder, and liver. BA homeostasis is tightly controlled by a complex interplay with the nuclear receptor farnesoid X receptor (FXR), the enterokine hormone fibroblast growth factor 15 (FGF15) or the human ortholog FGF19 (FGF19). Circulating FGF19 to the FGFR4/β-Klotho receptor causes smooth muscle relaxation and refilling of the gallbladder. In the liver the binding activates the FXR-small heterodimer partner (SHP) pathway. This step suppresses the unnecessary BA synthesis and promotes the continuous enterohepatic circulation of BAs. Besides BA homeostasis, the BA-FXR-FGF19 axis governs several metabolic processes, hepatic protein, and glycogen synthesis, without inducing lipogenesis. These pathways can be disrupted in cholestasis, nonalcoholic fatty liver disease, and hepatocellular carcinoma. Thus, targeting FXR activity can represent a novel therapeutic approach for the prevention and the treatment of liver and metabolic diseases.

Promising traditional Chinese medicine for the treatment of cholestatic liver disease process (cholestasis, hepatitis, liver fibrosis, liver cirrhosis)

ETHNOPHARMACOLOGICAL RELEVANCE

Cholestatic liver disease (CLD) is mainly characterized by cholestasis. If not treated, it will deteriorate to cholestatic hepatitis, liver fibrosis, liver cirrhosis, and even liver failure. CLD has a high clinical incidence, and limited treatment with single therapy. In the long-term clinical exploration, traditional Chinese medicine (TCM) has been corroborated with unique therapeutic effects on the CLD process.

AIM OF THIS REVIEW

This paper summarizes the effective single and compound TCMs for the treatment of CLD. According to 4 important clinical stages of CLD: cholestasis, hepatitis, liver fibrosis, liver cirrhosis, pharmacological effects and mechanisms of 5 typical TCM examples are reviewed, aims to provide basis for clinical drug selection in different processes of CLD.

MATERIALS AND METHODS

Relevant scientific articles regarding therapeutic effects of TCM for the CLD were collected from different databases. We collated three single herbs including Artemisia scoparia Waldst. et Kit. or Artemisia capillaris Thunb. (Artemisiae Scopariae Herba, Yin Chen in Chinese), Paeonia lactiflora Pall. or Paeonia veitchii Lynch. (Paeoniae radix rubra, Chi Shao in Chinese), Poria cocos (Schw.) Wolf (Poria, Fu Ling in Chinese), and two compound herbs of Huang Qi Decoction (HQD) and Yin Chen Hao Decoction (YCHD) to studied and analyzed.

RESULTS

We proposed five promising TCMs treatments for the important developmental stages of CLD. Among them, Yin Chen is an essential medicine for protecting liver and gallbladder, and its TCM prescription is also a promising strategy for cholestasis. Based on clinical evidence, high-dose application of Chi Shao is a clinical special treatment of cholestasis hepatitis. Fu Ling can regulate immune cells and increase antibody levels in serum, which is expected to be an emerging therapy to prevent cholestatic liver fibrosis to cirrhosis. HQD can be used as routine clinical medicine for liver fibrosis. In addition, YCHD can exert better comprehensive advantages with multiple components, can treat the whole course of CLD and prevent it from developing to the end-stage.

CONCLUSION

Yin Chen, Chi Shao, Fu Ling, HQD and YCHD have shown good clinical efficacy in controlling the development of CLD. Clinically, it is easier to curb the development of CLD by adopting graded diagnosis and treatment measures. We suggest that CLD should be risk stratified in clinical treatment to ensure personalized treatment for patients, so as to slow down the development of the disease.

The immune response as a therapeutic target in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a complex and heterogeneous disorder considered a liver-damaging manifestation of metabolic syndrome. Its prevalence has increased in the last decades due to modern-day lifestyle factors associated with overweight and obesity, making it a relevant public health problem worldwide. The clinical progression of NAFLD is associated with advanced forms of liver injury such as fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). As such, diverse pharmacological strategies have been implemented over the last few years, principally focused on metabolic pathways involved in NAFLD progression. However, a variable response rate has been observed in NAFLD patients, which is explained by the interindividual heterogeneity of susceptibility to liver damage. In this scenario, it is necessary to search for different therapeutic approaches. It is worth noting that chronic low-grade inflammation constitutes a central mechanism in the pathogenesis and progression of NAFLD, associated with abnormal composition of the intestinal microbiota, increased lymphocyte activation in the intestine and immune effector mechanisms in liver. This review aims to discuss the current knowledge about the role of the immune response in NAFLD development. We have focused mainly on the impact of altered gut-liver-microbiota axis communication on immune cell activation in the intestinal mucosa and the role of subsequent lymphocyte homing to the liver in NAFLD development. We further discuss novel clinical trials that addressed the control of the liver and intestinal immune response to complement current NAFLD therapies.

Melatonin relieves hepatic lipid dysmetabolism caused by aging via modifying the secondary bile acid pattern of gut microbes

It has been reported that aging-generated gut microecosystem may promote host hepatic lipid dysmetabolism through shaping the pattern of secondary bile acids (BAs). Then as an oral drug, melatonin (Mel)-mediated beneficial efforts on the communication between gut microbiota and aging host are still not clearly. Here, we show that aging significantly shapes the pattern of gut microbiota and BAs, whereas Mel treatment reverses these phenotypes (P < 0.05), which is identified to depend on the existence of gut microbiota. Mechanistically, aging-triggered high-level expression of ileac farnesoid X receptor (FXR) is significantly decreased through Mel-mediated inhibition on Campylobacter jejuni (C. jejuni)-induced deconjugation of tauroursodeoxycholic acid (TUDCA) and glycoursodeoxycholic acid (GUDCA) (P < 0.05). The aging-induced high-level of serum taurine chenodeoxycholic acid (TCDCA) activate trimethylamine-N-oxide (TMAO)-triggered activating transcriptional factor 4 (ATF4) signaling via hepatic FXR, which further regulates hepatic BAs metabolism, whereas TUDCA inhibits aging-triggered high-level of hepatic ATF4. Overall, Mel reduces C. jejuni-mediated deconjugation of TUDCA to inhibit aging-triggered high-level expression of hepatic FXR, which further decreases hepatic TMAO production, to relieve hepatic lipid dysmetabolism.

Design, synthesis and cytotoxic evaluation of novel betulonic acid-diazine derivatives as potential antitumor agents

With the purpose to improve antiproliferative activity, 26 new betulonic acid-diazine derivatives were designed and synthesized from betulinic acid. The anticancer activity of these semi-synthetic compounds was evaluated by MTT assay in both tumor cell lines and normal cell line. The results indicated that majority of new compounds exhibited improved antitumor activity compared with the parent compound betulonic acid. Compound BoA2C, in particular, had the most significant action with IC50 value of 3.39 μM against MCF-7 cells, while it showed lower cytotoxicity on MDCK cell line than cisplatin. Furthermore, we discovered that BoA2C strongly increased MCF-7 cell damage mostly by influencing arginine and fatty acid metabolism. In addition, the structure-activity relationships were briefly discussed. The results of this study suggested that the introduction of different diazines at C-28 could selectively inhibit different kinds of cancer cells and might be an effective way to synthesize potent anticancer lead compound from betulonic acid.