Metformin impairs bile acid homeostasis in ethinylestradiol-induced cholestasis in mice

Ameliorative effects of Bacillus subtilis C10 on alcoholic liver injury in mice

Bacillus subtilis has been reported to maintain the homeostasis of intestinal flora. In this study, a mouse model of alcoholic liver injury (ALI) was constructed to study the ameliorative effect of B. subtilis C10 on ALI and to further clarify its mechanism of action. Significant correlations between intestinal flora and biochemical indicators of ALI were found by statistical correlation analysis. Supplementation with B. subtilis C10 modulated the equilibrium of gut flora by reducing the population of detrimental bacteria while enhancing the numbers of beneficial microorganisms, which resulted in an improvement in lipid metabolism and oxidative stress in the liver. The results of RT-qPCR showed that B. subtilis C10 intervention regulated the main regulatory factors of liver lipid metabolism (PPAR-α, SREBP-1c) and interfered with Nrf-2/Ho-1 signal pathway, which in turn ameliorated alcohol-induced lipid metabolism disorder and liver peroxidation stress. In addition, liver metabonomic analysis showed that B. subtilis C10 intervention reduced the production of harmful metabolites and increased beneficial metabolites in the liver, thereby reversing the metabolic disturbances caused by excessive alcohol consumption. KEGG analysis showed that B. subtilis C10 intervention modulated liver metabolic disorders and accelerated lipid metabolism by regulating glutathione metabolic pathway, purine metabolic pathway, pantothenic acid and CoA biosynthesis pathway, ABC transporter protein pathway, and HIF-1 signaling pathway. Taken together, these findings suggest that B. subtilis C10 ameliorates ALI by modifying the structure of intestinal flora and liver metabolic pathways to attenuate alcohol-exposure-induced liver oxidative damage and lipid metabolism abnormalities. PRACTICAL APPLICATION: Bacillus subtilis C10 is an effective probiotic intervention that significantly ameliorated alcoholic liver injury in mice through the gut-liver axis. B. subtilis C10 can be used as a dietary probiotic to develop functional foods with beneficial effects for the population of excessive alcohol consumption.

Intrahepatic cholestasis of pregnancy: Introduction and overview 2024

Considerable progress has been made to explain the aetiology of intrahepatic cholestasis of pregnancy (ICP) and of the adverse pregnancy outcomes associated with high maternal total serum bile acids (TSBAs). The reported thresholds for non-fasting TSBA associated with the risk of stillbirth and spontaneous preterm birth can be used to identify pregnancies at risk of these adverse outcomes to decide on appropriate interventions and to give reassurance to women with lower concentrations of TSBA. Data also support the use of ursodeoxycholic acid to protect against the risk of spontaneous preterm birth. A previous history of ICP may be associated with higher rates of subsequent hepatobiliary disease: if there is a suspicion of underlying susceptibility, clinicians caring for women with ICP should screen for associated disorders or for genetic susceptibility and, where appropriate, refer for ongoing hepatology review.

Research progress on the relationship between bile acid metabolism and type 2 diabetes mellitus

Bile acids, which are steroid molecules originating from cholesterol and synthesized in the liver, play a pivotal role in regulating glucose metabolism and maintaining energy balance. Upon release into the intestine alongside bile, they activate various nuclear and membrane receptors, influencing crucial processes. These bile acids have emerged as significant contributors to managing type 2 diabetes mellitus, a complex clinical syndrome primarily driven by insulin resistance. Bile acids substantially lower blood glucose levels through multiple pathways: BA-FXR-SHP, BA-FXR-FGFR15/19, BA-TGR5-GLP-1, and BA-TGR5-cAMP. They also impact blood glucose regulation by influencing intestinal flora, endoplasmic reticulum stress, and bitter taste receptors. Collectively, these regulatory mechanisms enhance insulin sensitivity, stimulate insulin secretion, and boost energy expenditure. This review aims to comprehensively explore the interplay between bile acid metabolism and T2DM, focusing on primary regulatory pathways. By examining the latest advancements in our understanding of these interactions, we aim to illuminate potential therapeutic strategies and identify areas for future research. Additionally, this review critically assesses current research limitations to contribute to the effective management of T2DM.

Labetalol and soluble endoglin aggravate bile acid retention in mice with ethinylestradiol-induced cholestasis

Labetalol is used for the therapy of hypertension in preeclampsia. Preeclampsia is characterized by high soluble endoglin (sEng) concentration in plasma and coincides with intrahepatic cholestasis during pregnancy (ICP), which threatens the fetus with the toxicity of cumulating bile acids (BA). Therefore, we hypothesized that both labetalol and increased sEng levels worsen BA cumulation in estrogen-induced cholestasis. C57BL/6J, transgenic mice overexpressing human sEng, and their wild-type littermates were administrated with ethinylestradiol (EE, 10 mg/kg s.c., the mice model of ICP) and labetalol (10 mg/kg s.c.) for 5 days with sample collection and analysis. Plasma was also taken from healthy pregnant women and patients with ICP. Administration of labetalol to mice with EE cholestasis aggravated the increase in BA plasma concentrations by induction of hepatic Mrp4 efflux transporter. Labetalol potentiated the increment of sEng plasma levels induced by estrogen. Increased plasma levels of sEng were also observed in patients with ICP. Moreover, increased plasma levels of human sEng in transgenic mice aggravated estrogen-induced cholestasis in labetalol-treated mice and increased BA concentration in plasma via enhanced reabsorption of BAs in the ileum due to the upregulation of the Asbt transporter. In conclusion, we demonstrated that labetalol increases plasma concentrations of BAs in estrogen-induced cholestasis, and sEng aggravates this retention. Importantly, increased sEng levels in experimental and clinical forms of ICPs might present a novel mechanism explaining the coincidence of ICP with preeclampsia. Our data encourage BA monitoring in the plasma of pregnant women with preeclampsia and labetalol therapy.

Enhancing intestinal barrier efficiency: A novel metabolic diseases therapy

Physiologically, the intestinal barrier plays a crucial role in homeostasis and nutrient absorption and prevents pathogenic entry, harmful metabolites, and endotoxin absorption. Recent advances have highlighted the association between severely damaged intestinal barriers and diabetes, obesity, fatty liver, and cardiovascular diseases. Evidence indicates that an abated intestinal barrier leads to endotoxemia associated with systemic inflammation, insulin resistance, diabetes, and lipid accumulation, accelerating obesity and fatty liver diseases. Nonetheless, the specific mechanism of intestinal barrier damage and the effective improvement of the intestinal barrier remain to be explored. Here, we discuss the crosstalk between changes in the intestinal barrier and metabolic disease. This paper also highlights how to improve the gut barrier from the perspective of natural medicine, gut microbiota remodeling, lifestyle interventions, and bariatric surgery. Finally, potential challenges and prospects for the regulation of the gut barrier-metabolic disease axis are discussed, which may provide theoretical guidance for the treatment of metabolic diseases.

A water-soluble tomato extract rich in secondary plant metabolites lowers trimethylamine-n-oxide and modulates gut microbiota: a randomized, double-blind, placebo-controlled cross-over study in overweight and obese adults

BACKGROUND

Natural products rich in polyphenols have been shown to lower plasma trimethylamine-n-oxide (TMAO) known for its proatherogenic effects by modulating the intestinal microbiota.

OBJECTIVES

We aimed to determine the impact of Fruitflow, a water-soluble tomato extract, on TMAO, fecal microbiota, and plasma and fecal metabolites.

METHODS

Overweight and obese adults (n = 22, BMI 28-35 kg/m²) were included in a double-blind, placebo-controlled, cross-over study receiving 2×150 mg Fruitflow per day or placebo (maltodextrin) for 4 wk with a 6-week wash-out between interventions. Stool, blood, and urine samples were collected to assess changes in plasma TMAO (primary outcome) as well as fecal microbiota, fecal and plasma metabolites, and urine TMAO (secondary outcomes). In a subgroup (n = 9), postprandial TMAO was evaluated following a choline-rich breakfast (∼450 mg). Statistical methods included paired t-tests or Wilcoxon signed rank tests and permutational multivariate analysis of variance.

RESULTS

Fruitflow, but not placebo, reduced fasting levels of plasma (-1.5 μM, P ≤ 0.05) and urine (-19.1 μM, P ≤ 0.01) TMAO as well as plasma lipopolysaccharides (-5.3 ng/mL, P ≤ 0.05) from baseline to the end of intervention. However, these changes were significant only for urine TMAO levels when comparing between the groups (P ≤ 0.05). Changes in microbial beta, but not alpha, diversity paralleled this with a significant difference in Jaccard distance-based Principal Component (P ≤ 0.05) as well as decreases in Bacteroides, Ruminococccus, and Hungatella and increases in Alistipes when comparing between and within groups (P ≤ 0.05, respectively). There were no between-group differences in SCFAs and bile acids (BAs) in both faces and plasma but several changes within groups such as an increase in fecal cholic acid or plasma pyruvate with Fruitflow (P ≤ 0.05, respectively). An untargeted metabolomic analysis revealed TMAO as the most discriminant plasma metabolite between groups (P ≤ 0.05).

CONCLUSIONS

Our results support earlier findings that polyphenol-rich extracts can lower plasma TMAO in overweight and obese adults related to gut microbiota modulation. This trial was registered at clinicaltrials.gov as NCT04160481 (https://clinicaltrials.gov/ct2/show/NCT04160481?term= Fruitflow&draw= 2&rank= 2).

Monascuspiloin from Monascus-Fermented Red Mold Rice Alleviates Alcoholic Liver Injury and Modulates Intestinal Microbiota

Monascus-fermented red mold rice (RMR) has excellent physiological efficacy on lipid metabolism and liver function. This study investigated the ameliorative effects of monascuspiloin (MP) from RMR on alcoholic liver injury in mice, and further clarified its mechanism of action. Results showed that MP intervention obviously ameliorated lipid metabolism and liver function in mice with over-drinking. In addition, dietary MP intervention reduced liver MDA levels and increased liver CAT, SOD, and GSH levels, thus alleviating liver oxidative stress induced by excessive drinking. 16S rRNA amplicon sequencing showed that MP intervention was beneficial to ameliorate intestinal microbiota dysbiosis by elevating the proportion of norank_f_Lachnospiraceae, Lachnoclostridium, Alistipes, Roseburia, Vagococcus, etc., but decreasing the proportion of Staphylococcus, norank_f_Desulfovibrionaceae, Lachnospiraceae_UCG-001, Helicobacter, norank_f_Muribaculaceae, unclassified_f_Ruminococcaceae, etc. Additionally, correlation network analysis indicated that the key intestinal bacterial taxa intervened by MP were closely related to some biochemical parameters of lipid metabolism, liver function, and oxidative stress. Moreover, liver metabolomics analysis revealed that dietary MP supplementation significantly regulated the levels of 75 metabolites in the liver, which were involved in the synthesis and degradation of ketone bodies, taurine, and hypotaurine metabolism, and other metabolic pathways. Furthermore, dietary MP intervention regulated gene transcription and protein expression associated with hepatic lipid metabolism and oxidative stress. In short, these findings suggest that MP mitigates alcohol-induced liver injury by regulating the intestinal microbiome and liver metabolic pathway, and thus can serve as a functional component to prevent liver disease.

Ganoderic acid A from Ganoderma lucidum protects against alcoholic liver injury through ameliorating the lipid metabolism and modulating the intestinal microbial composition

Alcoholic liver injury is mainly caused by long-term excessive alcohol consumption and has become a global public threat to human health. It is well known that Ganoderma lucidum has excellent beneficial effects on liver function and lipid metabolism. The object of this study was to investigate the hepatoprotective effects of ganoderic acid A (GAA, one of the main triterpenoids in G. lucidum) against alcohol-induced liver injury and reveal the underlying mechanisms of its protective effects. The results showed that oral administration of GAA significantly inhibited the abnormal elevation of the liver index, serum total triglyceride (TG), cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in mice exposed to alcohol intake, and also significantly protected the liver against alcohol-induced excessive lipid accumulation and pathological changes. Besides, alcohol-induced oxidative stress in the liver was significantly ameliorated by the dietary intervention of GAA through decreasing the hepatic levels of lactate dehydrogenase (LDH) and malondialdehyde (MDA), and increasing hepatic activities of catalase (CAT), superoxide dismutase (SOD), alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), and hepatic levels of glutathione (GSH). In addition, GAA intervention evidently ameliorated intestinal microbial disorder by markedly increasing the abundance of Muribaculaceae, Prevotellaceae, Jeotgalicoccus, Bilophila, Family_XIII_UCG_001, Aerococcus, Ruminococcaceae_UCG_005, Harryflintia, Christensenellaceae, Rumonpcpccaceae, Prevotelaceae_UCG_001, Clostridiales_vadinBB60_group, Parasutterella and Bifidobacterium, but decreasing the proportion of Lactobacillus, Burkholderia_Caballeroria_Paraburkholderia, Escherichia_Shigella and Erysipelatoclostridium. Furthermore, liver metabolomics based on UPLC-QTOF/MS demonstrated that oral administration of GAA had a significant regulatory effect on the composition of liver metabolites in mice exposed to alcohol intake, especially the levels of the biomarkers involved in the metabolic pathways of riboflavin metabolism, glycine, serine and threonine metabolism, pyruvate metabolism, glycolysis/gluconeogenesis, biosynthesis of unsaturated fatty acids, synthesis and degradation of ketone bodies, fructose and mannose metabolism. Moreover, dietary supplementation of GAA significantly regulated the hepatic mRNA levels of lipid metabolism and inflammatory response related genes. Conclusively, these findings demonstrate that GAA has beneficial effects on alleviating alcohol-induced liver injury and is expected to become a new functional food ingredient for the prevention of alcoholic liver injury.

Multidrug Resistance-Associated Protein 2 Deficiency Aggravates Estrogen-Induced Impairment of Bile Acid Metabolomics in Rats

Multidrug resistance-associated protein 2 (Mrp2) mediates biliary secretion of anionic endobiotics and xenobiotics. Genetic alteration of Mrp2 leads to conjugated hyperbilirubinemia and predisposes to the development of intrahepatic cholestasis of pregnancy (ICP), characterized by increased plasma bile acids (BAs) due to mechanisms that are incompletely understood. Therefore, this study aimed to characterize BA metabolomics during experimental Mrp2 deficiency and ICP. ICP was modeled by ethinylestradiol (EE) administration to Mrp2-deficient (TR) rats and their wild-type (WT) controls. Spectra of BAs were analyzed in plasma, bile, and stool using an advanced liquid chromatography–mass spectrometry (LC–MS) method. Changes in BA-related genes and proteins were analyzed in the liver and intestine. Vehicle-administered TR rats demonstrated higher plasma BA concentrations consistent with reduced BA biliary secretion and increased BA efflux from hepatocytes to blood via upregulated multidrug resistance-associated protein 3 (Mrp3) and multidrug resistance-associated protein 4 (Mrp4) transporters. TR rats also showed a decrease in intestinal BA reabsorption due to reduced ileal sodium/bile acid cotransporter (Asbt) expression. Analysis of regulatory mechanisms indicated that activation of the hepatic constitutive androstane receptor (CAR)-Nuclear factor erythroid 2-related factor 2 (Nrf2) pathway by accumulating bilirubin may be responsible for changes in BA metabolomics in TR rats. Ethinylestradiol administration to TR rats further increased plasma BA concentrations as a result of reduced BA uptake and increased efflux via reduced Slco1a1 and upregulated Mrp4 transporters. These results demonstrate that Mrp2-deficient organism is more sensitive to estrogen-induced cholestasis. Inherited deficiency in Mrp2 is associated with activation of Mrp3 and Mrp4 proteins, which is further accentuated by increased estrogen. Bile acid monitoring is therefore highly desirable in pregnant women with conjugated hyperbilirubinemia for early detection of intrahepatic cholestasis.