Sodium butyrate alleviates cholesterol gallstones by regulating bile acid metabolism

Gut microbiota promotes cholesterol gallstone formation through the gut-metabolism-gene axis

BACKGROUND

Gallstone disease, arising from the interplay between host metabolism and gut microbiota, represents a significant health concern. Dysbiosis of the gut microbiome and disruptions in circadian rhythm contribute to the pathogenesis of gallstones. This study conducted a comprehensive analysis of gut microbiota and metabolites derived from stool and serum samples of 28 patients with cholesterol gallstones (CGS) and 19 healthy controls, employing methodologies such as 16S rRNA sequencing, metaproteomics, metabolomics, and host genetic analysis. Additionally, a retrospective cohort study was utilized to assess the efficacy of probiotics or ursodeoxycholic acid (UDCA) in preventing CGS formation post-bariatric surgery.

RESULTS

In CGS patients, gut microbiota diversity shifted, with harmful bacteria rising and beneficial ones declining. The altered microbiota primarily affected amino acid, lipid, nucleotide, and carbohydrate metabolism. Metabolic abnormalities were noted in amino acids, glucose, lipids, and bile acids with decreased levels of ursodeoxycholic, glycosodeoxycholic, and glycolithocholic acids, and increased glycohyodeoxycholic and allocholic acids. Glutamine and alanine levels dropped, while phenylalanine and tyrosine rosed. Animal studies confirmed gene changes in gallbladder tissues related to bile acid, energy, glucose, and lipid metabolism. Importantly, UDCA and probiotics effectively reduced CGS risk post-bariatric surgery, especially when combined.

CONCLUSIONS

Multi-omics can clarify CGS pathology, by focusing on the gut-metabolism-gene axis, paving the way for future studies on CGS prevention and treatment through gut microbiota or metabolic interventions.

Sodium butyrate activates peroxisome proliferator-activated receptor γ to suppress lithogenic diet-induced cholesterol gallstones in mice

Peroxisome proliferator-activated receptor γ (PPAR-γ) is crucial in forming cholesterol stones. Sodium butyrate (NaB), a short-chain fatty acid, shows potential for gallstone treatment by activating PPAR-γ. This study aimed to elucidate the effects of NaB on cholesterol gallstones in mice fed a lithogenic diet (LD). Ezetimibe (5 mg/day) was used as a positive control, and a PPAR-γ antagonist (CW9661, 4 mg/kg/day) was used to investigate PPAR-γ. Body weight, gallstone incidence, lipid concentrations in blood, bile, and liver, liver function evaluation, histological analysis, and cholesterol metabolism-related gene expression were evaluated. NaB and ezetimibe suppressed gallstone formation, serum AST, ALT, and ALP levels, and serum/liver TG and TC. They also reduced bile cholesterol and phospholipids, and liver histological damage. NaB activated PPAR-γ, CYP7A1, ABCA1, and ABCB11 while suppressing ABCG5/G8 gene expression. CW9661 reversed NaB's benefits in LD mice. This study provides scientific evidence that NaB activated PPAR-γ to improve gallstones.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-024-01721-x.

Gut microbiome and metabolome characteristics of patients with cholesterol gallstones suggest the preventive potential of prebiotics

Cholesterol gallstones (CGS) still lack effective noninvasive treatment. The etiology of experimentally proven cholesterol stones remains underexplored. This cross-sectional study aims to comprehensively evaluate potential biomarkers in patients with gallstones and assess the effects of microbiome-targeted interventions in mice. Microbiome taxonomic profiling was conducted on 191 samples via V3-V4 16S rRNA sequencing. Next, 60 samples (30 age- and sex-matched CGS patients and 30 controls) were selected for metagenomic sequencing and fecal metabolite profiling via liquid chromatography-mass spectrometry. Microbiome and metabolite characterizations were performed to identify potential biomarkers for CGS. Eight-week-old male C57BL/6J mice were given a lithogenic diet for 8 weeks to promote gallstone development. The causal relationship was examined through monocolonization in antibiotics-treated mice. The effects of short-chain fatty acids such as sodium butyrate, sodium acetate (NaA), sodium propionate, and fructooligosaccharides (FOS) on lithogenic diet-induced gallstones were investigated in mice. Gut microbiota and metabolites exhibited distinct characteristics, and selected biomarkers demonstrated good diagnostic performance in distinguishing CGS patients from healthy controls. Multi-omics data indicated associations between CGS and pathways involving butanoate and propanoate metabolism, fatty acid biosynthesis and degradation pathways, taurine and hypotaurine metabolism, and glyoxylate and dicarboxylate metabolism. The incidence of gallstones was significantly higher in the Clostridium glycyrrhizinilyticum group compared to the control group in mice. The grade of experimental gallstones in control mice was significantly higher than in mice treated with NaA and FOS. FOS could completely inhibit the formation of gallstones in mice. This study characterized gut microbiome and metabolome alterations in CGS. C. glycyrrhizinilyticum contributed to gallstone formation in mice. Supplementing with FOS could serve as a potential approach for managing CGS by altering the composition and functionality of gut microbiota.

Perspectives on the involvement of the gut microbiota in salt-sensitive hypertension

Salt-sensitivity hypertension (SSH) is an independent predictor of cardiovascular event-related death. Despite the extensiveness of research on hypertension, which covers areas such as the sympathetic nervous system, the renin-angiotensin system, the vascular system, and the immune system, its pathogenesis remains elusive, with sub-optimal blood pressure control in patients. The gut microbiota is an important component of nutritional support and constitutes a barrier in the host. Long-term high salt intake can lead to gut microbiota dysbiosis and cause significant changes in the expression of gut microbiota-related metabolites. Of these metabolites, short chain fatty acids (SCFAs), trimethylamine oxide, amino acids, bile acids, and lipopolysaccharide are essential mediators of microbe-host crosstalk. These metabolites may contribute to the incidence and development of SSH via inflammatory, immune, vascular, and nervous pathways, among others. In addition, recent studies, including those on the histone deacetylase inhibitory mechanism of SCFAs and the blood pressure-decreasing effects of H2S via vascular activation, suggest that several proteins and factors in the classical pathway elicit their effects through multiple non-classical pathways. This review summarizes changes in the gut microbiota and its related metabolites in high-salt environments, as well as corresponding treatment methods for SSH, such as diet management, probiotic and prebiotic use, antibiotic use, and fecal transplantation, to provide new insights and perspectives for understanding SSH pathogenesis and the development of strategies for its treatment.

FGF21-dependent alleviation of cholestasis-induced liver fibrosis by sodium butyrate

Background

The beneficial effects of fibroblast growth factor 21 (FGF21) and sodium butyrate (NaB) on protection against cholestasis-induced liver fibrosis are not well known. This study aimed to explore the effects of FGF21 and NaB on bile duct ligation (BDL)-induced liver fibrosis.

Methods

Wild-type (WT) and FGF21 knockout (KO) mice received BDL surgery for 14 days. Liver fibrosis was assessed by Masson's staining for fibrosis marker expressions at the mRNA or protein levels. Adenovirus-mediated FGF21 overexpression in the WT mice was assessed against BDL damage. BDL surgeries were performed in WT and FGF21 KO mice that were administered either phosphate-buffered saline or NaB. The effects of NaB on the energy metabolism and gut microbiota were assessed using stable metabolism detection and 16S rRNA gene sequencing.

Results

BDL-induced liver fibrosis in the WT mice was accompanied by high induction of FGF21. Compared to the WT mice, the FGF21 KO mice showed more severe liver fibrosis induced by BDL. FGF21 overexpression protected against BDL-induced liver fibrosis, as proved by the decreasing α-SMA at both the mRNA and protein levels. NaB administration enhanced the glucose and energy metabolisms as well as remodeled the gut microbiota. NaB alleviated BDL-induced liver fibrosis in the WT mice but aggravated the same in FGF21 KO mice.

Conclusion

FGF21 plays a key role in alleviating cholestasis-induced liver damage and fibrosis. NaB has beneficial effects on cholestasis in an FGF21-dependent manner. NaB administration can thus be a novel nutritional therapy for treating cholestasis via boosting FGF21 signaling and regulating the gut microbiota.

Alteration of serum bile acids in amyotrophic lateral sclerosis

Hydrophilic endogenous bile acids ursodeoxycholic acid (UDCA), tauroursodeoxycholic acid (TUDCA), and glucourosodeoxycholic acid (GUDCA) have suggested neuroprotective effects. We performed a case-control study to examine the association between ALS diagnosis and serum levels of bile acids. Sporadic and familial ALS patients, age- and sex-matched healthy controls, and presymptomatic gene carriers who donated blood samples were included. Non-fasted serum samples stored at -80°C were used for the analysis. Serum bile acid levels were measured by liquid chromatography-mass spectrometry (LC-MS). Concentrations of 15 bile acids were obtained, 5 non-conjugated and 10 conjugated, and compared between ALS versus control groups (presymptomatic gene carriers + healthy controls) using the Wilcoxon-Rank-Sum test. In total, 80 participants were included: 31 ALS (17 sporadic and 14 familial ALS); 49 controls (22 gene carriers, 27 healthy controls). The mean age was 50 years old and 50% were male. In the ALS group, 45% had familial disease with a pathogenic variant in C9orf72 (29%), TARDBP (10%), FUS (3%), and CHCHD10 (3%) genes. In the control group, 43% carried pathogenic variants: C9orf72 (27%), SOD1 (10%), and FUS (6%). The serum levels of UDCA, TUDCA, and GUDCA trended higher in the ALS group compared to controls (median 27 vs. 7 nM, 4 vs. 3 nM, 110 vs. 47 nM, p-values 0.04, 0.06, 0.04, respectively). No significant group differences were found in other bile acids serum levels. In conclusion, the serum level of UDCA, TUDCA, GUDCA trended higher in ALS patients compared to controls, and no evidence of deficiencies was found.

Microbiome-Metabolome Analysis Insight into the Effects of the Extract of Phyllanthus emblica L. on High-Fat Diet-Induced Hyperlipidemia

The fruit of Phyllanthus emblica L. (FEPE) has a long history of use in Asian folk medicine. The main bioactive compounds in FEPE are polyphenols, known for their potent antioxidant, anti-inflammatory, and hypolipidemic activities. The present study aimed to investigate the intervention effect of FEPE (100 and 200 mg/kg) on hyperlipidemia for 8 weeks and preliminarily explored the potential mechanism by microbiome-metabolome analysis. The results showed that a high-dose FEPE (200 mg/kg) effectively alleviated dyslipidaemic symptoms and body weight gain in hyperlipidemic mice induced by a high-fat diet (HFD). Microbiome analysis showed that FEPE altered the structure of the intestinal microbiota, which included an increase in specific probiotics (such as Akkermansia, Anaerovorax, and Bacteroides) and a decrease in harmful bacteria (including A2, Acetitomaculum, Candidatus_Arthromitus, Lachnospiraceae_NK4A136_group, Lachnospiraceae_NK4B4_group, Rikenella, and Streptococcus), as well as a reduction in the level of short-chain fatty acids (SCFAs). In addition, significant changes in the hepatic metabolome were observed, and eight key metabolites associated with betaine metabolism, lysine degradation, methionine metabolism, and fatty acid metabolism pathways were primarily filtered. The correlated analysis identified several key "microbiota-metabolite" axes in the treatment of hyperlipidemia by FEPE extract. In conclusion, the present study is expected to provide a basis for treating hyperlipidemia with FEPE from the perspective of the microbiome-liver metabolome axis.

Association between gut microbiota and autoimmune cholestatic liver disease, a Mendelian randomization study

Background

Previous studies have suggested that the gut microbiota (GM) is closely associated with the development of autoimmune cholestatic liver disease (ACLD), but limitations, such as the presence of confounding factors, have resulted in a causal relationship between the gut microbiota and autoimmune cholestatic liver disease that remains uncertain. Thus, we used two-sample Mendelian randomization as a research method to explore the causal relationship between the two.

Methods

Pooled statistics of gut microbiota from a meta-analysis of genome-wide association studies conducted by the MiBioGen consortium were used as an instrumental variable for exposure factors. The Pooled statistics for primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) were obtained from the R9 version of the FinnGen database (https://r9.finngen.fi/). Inverse-variance Weighted (IVW), cML-MA, MR-Egger regression, Weighted median (WME), Weighted mode (WM), and Simple mode (SM) were used to detect the association between intestinal flora and the causal relationship between intestinal flora and ACLD, in which IVW method was dominant, was assessed based on the effect indicator dominance ratio (odds ratio, OR) and 95% confidence interval (CI). Sensitivity analysis, heterogeneity test, gene pleiotropy test, MR pleiotropy residual sum and outlier test (MR-PRESSO) were combined to verify the stability and reliability of the results. Reverse Mendelian randomization analysis was performed on gut microbiota and found to be causally associated with ACLD.

Results

The IVW results showed that the relative abundance of the genus Clostridium innocuum group, genus Butyricicoccus, and genus Erysipelatoclostridium was negatively correlated with the risk of PBC, that is, increased abundance reduced the risk of PBC and was a protective, and the relative abundance of the genus Eubacterium hallii was positively correlated with the risk of PSC, which is a risk factor for PSC. Family Clostridiaceae1 and family Lachnospiraceae were negatively correlated with the risk of PSC, which is a protective factor for PSC.

Conclusion

This study found a causal relationship between gut microbiota and ACLD. This may provide valuable insights into gut microbiota-mediated pathogenesis of ACLD. It is necessary to conduct a large-sample randomized controlled trial (RCT) at a later stage to validate the associated role of the relevant gut microbiota in the risk of ACLD development and to explore the associated mechanisms.

Genetic evidence strengthens the bidirectional connection between gut microbiota and Shigella infection: insights from a two-sample Mendelian randomization study

Background

In recent investigations, substantial strides have been made in the precise modulation of the gut microbiota to prevent and treat a myriad of diseases. Simultaneously, the pressing issue of widespread antibiotic resistance and multidrug resistance resulting from Shigella infections demands urgent attention. Several studies suggest that the antagonistic influence of the gut microbiota could serve as a novel avenue for impeding the colonization of pathogenic microorganisms or treating Shigella infections. However, conventional research methodologies encounter inherent challenges in identifying antagonistic microbial agents against Shigella, necessitating a comprehensive and in-depth analysis of the causal relationship between Shigella infections and the gut microbiota.

Materials and methods

Utilizing the aggregated summary statistics from Genome-Wide Association Studies (GWAS), we conducted Mendelian Randomization (MR) analyses encompassing 18,340 participants to explore the interplay between the gut microbiota and Shigella infections. This investigation also involved 83 cases of Shigella infection patients and 336,396 control subjects. In the positive strand of our findings, we initially performed a preliminary analysis using the Inverse Variance Weighting (IVW) method. Subsequently, we undertook sensitivity analyses to assess the robustness of the results, addressing confounding factors' influence. This involved employing the Leave-One-Out method and scrutinizing funnel plots to ensure the reliability of the MR analysis outcomes. Conclusively, a reverse MR analysis was carried out, employing the Wald ratio method due to the exposure of individual Single Nucleotide Polymorphisms (SNPs). This was undertaken to explore the plausible associations between Shigella infections and genetically predicted compositions of the gut microbiota.

Results

In this study, we employed 2,818 SNPs associated with 211 species of gut microbiota as instrumental variables (IVs). Through IVW analysis, our positive MR findings revealed a significant negative correlation between the occurrence of Shigella infections and the phylum Tenericutes (OR: 0.18, 95% CI: 0.04-0.74, p = 0.02), class Mollicutes (OR: 0.18, 95% CI: 0.04-0.74, p = 0.02), genus Intestinimonas (OR: 0.16, 95% CI: 0.04-0.63, p = 0.01), genus Gordonibacter (OR: 0.39, 95% CI: 0.16-0.93, p = 0.03), and genus Butyrivibrio (OR: 0.44, 95% CI: 0.23-0.87, p = 0.02). Conversely, a positive correlation was observed between the occurrence of Shigella infections and genus Sutterella (OR: 10.16, 95% CI: 1.87-55.13, p = 0.01) and genus Alistipes (OR: 12.24, 95% CI: 1.71-87.34, p = 0.01). In sensitivity analyses, utilizing MR-Egger regression analysis and MR Pleiotropy Residual Sum and Outlier (MR-PRESSO) detection, all outcomes demonstrated robust stability. Simultaneously, in the reverse MR analysis, Shigella infections resulted in an upregulation of four bacterial genera and a downregulation of three bacterial genera.

Conclusion

In summation, the MR analysis outcomes corroborate the presence of bidirectional causal relationships between the gut microbiota and Shigella infections. This study not only unveils novel perspectives for the prevention and treatment of Shigella infections but also furnishes fresh insights into the mechanistic underpinnings of how the gut microbiota contributes to the pathogenesis of Shigella infections. Consequently, the established dual causal association holds promise for advancing our understanding and addressing the complexities inherent in the interplay between the gut microbiota and Shigella infections, thereby paving the way for innovative therapeutic interventions and preventive strategies in the realm of Shigella-related diseases.

Sodium butyrate restricts neutrophils migration and NETs formation through reducing macrophage-derived CXCL16 in calculous cholecystitis

Background

Neutrophil extracellular traps (NETs) havebeen demonstrated to initiate gallstone formation. Cholecystitis is a common complication of gallstones. As short-chain fatty acids (SCFAs), Butyrate acid has anti-inflammatory effects and alleviates cholesterol gallstones. However, the role of Butyrate acid in NETs of calculous cholecystitis and the molecular mechanism remains unclear. The effect of Sodium butyrate on neutrophil migration and NETs formation involved in macrophages polarization and exosomalCXCL16 in calculous cholecystitis was explored in our study.

Methods

The number of neutrophils and NETs, macrophages polarization and exosomal CXCL16 level were analyzed in clinic samples from patients. Exosomes were obtained and verified by gradient centrifugation, transmission electron microscopy, NanoSight analysis and Western blotting. Transwell, immunofluorescence and ELISA were used to detect neutrophil migration and NETs formation.

Results

Our results demonstrated that a large number of neutrophils and NETs, as well as M1 macrophages and exosomal CXCL16, were found in the blood of gallstones patients, especially patients with acute calculous cholecystitis. Exosomal CXCL16 was upregulated in plasma of calculous cholecystitis patients or Lipopolysaccharide induced macrophages, and promoted neutrophil cell migration and NETs formation. Sodium butyrate reduced exosomal CXCL16 secretion through the inhibition of M1 macrophage polarization to suppress neutrophils migration and NETs formation.

Conclusion

Our study suggested that Sodium butyrate may inhibit neutrophils migration and NETs formation to alleviate calculous cholecystitis by reducing exosomal CXCL16 secretion from macrophage and macrophage polarization.

General significance

Our finding may provide a link between exosomes and neutrophils to serve as a potential therapeutic intervention in calculous cholecystitis.

Cav-1 regulates the bile salt export pump on the canalicular membrane of hepatocytes by PKCα-associated signalling under cholesterol stimulation

BACKGROUND AND AIMS

The secretion of bile salts transported by the bile salt export pump (BSEP) is the primary driving force for the generation of bile flow; thus, it is closely related to the formation of cholesterol stones. Caveolin-1 (Cav-1), an essential player in cell signalling and endocytosis, is known to co-localize with cholesterol-rich membrane domains. This study illustrates the role of Cav-1 and BSEP in cholesterol stone formation.

METHODS

Adult male C57BL/6 mice were used as an animal model. HepG2 cells were cultured under different cholesterol concentrations and BSEP, Cav-1, p-PKCα and Hax-1 expression levels were determined via Western blotting. Expression levels of BSEP and Cav-1 mRNA were detected using real-time PCR. Immunofluorescence and immunoprecipitation assays were performed to study BSEP and Hax-1 distribution. Finally, an ATPase activity assay was performed to detect BSEP transport activity under different cholesterol concentrations in cells.

RESULTS

Under low-concentration stimulation with cholesterol, Cav-1 and BSEP protein and mRNA expression levels significantly increased, PKCα phosphorylation significantly decreased, BSEP binding capacity to Hax-1 weakened, and BSEP function increased. Under high-concentration stimulation with cholesterol, Cav-1 and BSEP protein and mRNA expression levels decreased, PKCα phosphorylation increased, BSEP binding capacity to Hax-1 rose, and BSEP function decreased.

CONCLUSION

Cav-1 regulates the bile salt export pump on the canalicular membrane of hepatocytes via PKCα-associated signalling under cholesterol stimulation.

Chaihu Shugan prevents cholesterol gallstone formation by ameliorating the microbiota dysbiosis and metabolic disturbance in mice

Introduction: Cholesterol gallstone (CGS) is a biliary tract disorder requiring treatment in approximately 20% of patients. The efficacy of Chaihu Shugan in preventing CGS recurrence after successful treatment remains uncertain. Methods: We examined the in vivo preventive efficacy of Chaihu Shugan using a CGS mouse model and used multi-omics to study the interplay between gut microbiota, metabolism, and gene expression. Results: The intestinal microbiota was severely dysregulated during the formation of CGS, showing a marked decrease in the abundance of beneficial microbiota, especially Lactobacillus and Akkermansia. Chaihu Shugan prevented CGS formation by restoring the composition of the gut microbiota and reversing the metabolic disturbances caused by dysbiosis. This preventive effect of Chaihu Shugan was paralleled by changes in the expression of metabolism-related genes in the liver. A network pharmacology analysis of Chaihu Shugan revealed that obacunone may be the key active metabolite in regulating bile acid metabolism. Multi-omics and correlation analyses elucidated the interplay between gut microbiota, metabolism, and gene alterations in the dose-dependent effect of Chaihu Shugan. Conclusion: Our data show that Chaihu Shugan can prevent CGS and indicate its mechanisms of action.

Gut microbiota, circulating metabolites, and gallstone disease: a Mendelian randomization study

Background

The link between Gut microbiota (GM) and Gallstone disease (GSD) is well established, but it is not clear whether there is a causal relationship between the two associations.

Methods

We conducted bidirectional Mendelian randomization (MR) analyses, leveraging aggregated data from the Genome-Wide Association Study (GWAS) of GM and Circulating Metabolites. Our primary objective was to investigate the causal interplay between intestinal flora and GSD. Additionally, we performed mediational analyses, two-step MR, and multivariate MR to uncover the potential mediating effect of circulating metabolites in this relationship.

Result

Our study has revealed a causal relationship between GSD and six distinct bacterial groups. Genetically predicted Class Bacilli (Odds Ratio (OR): 0.901, 95% Confidence Interval (95% CI): 0.825-0.985; p = 0.021), Order Lactobacillales (OR: 0.895, 95% CI: 0.816-0.981; p = 0.017), and Genus Coprococcus 2 (OR: 0.884, 95% CI: 0.804-0.973; p = 0.011) were inversely associated with the risk of GSD. Conversely, the Genus Clostridiumsensustricto1 (OR: 1.158, 95% CI: 1.029-1.303; p = 0.015), Genus Coprococcus3 (OR: 1.166, 95% CI: 1.024-1.327; p = 0.020), and Genus Peptococcus (OR: 1.070, 95% CI: 1.017-1.125; p = 0.009) were positively associated with the risk of GSD. Moreover, our findings suggest that the positive influence of the Genus Peptococcus on GSD may be mediated through Omega-3 polyunsaturated fatty acids (PUFA).

Conclusion

This study reinforces the connection between the gut microbiome and the risk of GSD while also unveiling the mediating role of Omega-3 PUFA in the causal relationship between these factors.

Gut microbiota causally affects cholelithiasis: a two-sample Mendelian randomization study

Background

The gut microbiota is closely linked to cholesterol metabolism-related diseases such as obesity and cardiovascular diseases. However, whether gut microbiota plays a causal role in cholelithiasis remains unclear.

Aims

This study explored the causal relationship between gut microbiota and cholelithiasis. We hypothesize that the gut microbiota influences cholelithiasis development.

Methods

A two-sample Mendelian randomization method was combined with STRING analysis to test this hypothesis. Summary data on gut microbiota and cholelithiasis were obtained from the MiBioGen (n=13,266) and FinnGen R8 consortia (n=334,367), respectively.

Results

Clostridium senegalense, Coprococcus3, and Lentisphaerae increased the risk of cholelithiasis and expressed more bile salt hydrolases. In contrast, Holdemania, Lachnospiraceae UCG010, and Ruminococcaceae NK4A214 weakly expressed bile salt hydrolases and were implied to have a protective effect against cholelithiasis by Mendelian randomization analysis.

Conclusion

Gut microbiota causally influences cholelithiasis and may be related to bile salt hydrolases. This work improves our understanding of cholelithiasis causality to facilitate the development of treatment strategies.

Hyodeoxycholic acid attenuates cholesterol gallstone formation via modulation of bile acid metabolism and gut microbiota

BACKGROUND & AIMS

Hyodeoxycholic acid (HDCA), a hydrophilic bile acid (BA), may prevent and suppress the formation of cholesterol gallstones (CGs). However, the mechanism by which HDCA prevents CGs formation remains unclear. This study aimed to investigate the underlying mechanism of HDCA in preventing CG formation.

METHODS

C57BL/6J mice were fed either a lithogenic diet (LD), a chow diet, or LD combined with HDCA. The concentration of BAs in the liver and ileum were determined using liquid chromatography-mass spectrometry (LC-MS/MS). Genes involved in cholesterol and BAs metabolism were detected using polymerase chain reaction (PCR). The gut microbiota in the faeces was determined using 16S rRNA.

RESULTS

HDCA supplementation effectively prevented LD-induced CG formation. HDCA increased the gene expression of BA synthesis enzymes, including Cyp7a1, Cyp7b1, and Cyp8b1, and decreased the expression of the cholesterol transporter Abcg5/g8 gene in the liver. HDCA inhibited LD-induced Nuclear farnesoid X receptor (Fxr) activation and reduced the gene expression of Fgf15 and Shp in the ileum. These data indicate that HDCA could prevent CGs formation partly by promoting BA synthesis in the liver and reduced the cholesterol efflux. In addition, HDCA administration reversed the LD-induced decrease in the abundance of norank_f_Muribaculaceae, which was inversely proportional to cholesterol levels.

CONCLUSIONS

HDCA attenuated CG formation by modulating BA synthesis and gut microbiota. This study provides new insights into the mechanism by which HDCA prevents CG formation.

LAY SUMMARY

In this study, we found that HDCA supplementation suppressed LD-induced CGs in mice by inhibiting Fxr in the ileum, enhancing BA synthesis, and increasing the abundance of norank_f_Muribaculaceae in the gut microbiota. HDCA can also downregulate the level of total cholesterol in the serum, liver, and bile.

Effect of Clostridium butyricum on the formation of primary choledocholithiasis based on intestinal microbiome and metabolome analysis

AIMS

To investigate the function and probable mechanism of Clostridium butyricum in the development of choledocholithiasis.

METHODS AND RESULTS

The lithogenic diet group and the lithogenic diet + C. butyricum group were used to develop the choledocholithiasis model. During the experiment, C. butyricum suspension was administered to the rats in the lithogenic diet + C. butyricum group. The findings demonstrated that the C. butyricum intervention decreased the Firmicutes/Bacteroidetes ratio in the colon of experimental animals given a lithogenic diet. The relative levels of Desulfovibrio (0.93%) and Streptococcus (0.38%) fell, whereas Lactobacillus (22.36%), Prevotella (14.09%), and bacteria that produce short-chain fatty acids increased. Finally, 68 distinct metabolic products were found based on nontargeted metabonomics, and 42 metabolic pathways associated to the various metabolites were enriched.

CONCLUSIONS

We found that C. butyricum decreased the development of choledocholithiasis. It keeps the equilibrium of the rat's gut microbiome intact and lowers the danger of bacterial infections of the gastrointestinal and biliary systems. It is hypothesized that by controlling lipid metabolism, it may also have an impact on the development of cholelithiasis.

Intermittent Fasting Alleviates Non-Alcoholic Steatohepatitis by Regulating Bile Acid Metabolism and Promoting Fecal Bile Acid Excretion in High-Fat and High-Cholesterol Diet Fed Mice

SCOPE

Intermittent fasting (IF) has a protective role across a wide range of chronic disorders, including obesity, diabetes, and cardiovascular disease, but its protection against non-alcoholic steatohepatitis (NASH) is still lacking. This study seeks to investigate how IF alleviates NASH by regulating gut microbiota and bile acids (BAs) composition.

METHODS AND RESULTS

Male C57BL/6 mice are fed a high-fat and high-cholesterol (HFHC) diet for 16 weeks to establish a NASH model. Mice then continued HFHC feeding and are treated with or without every other day fasting for 10 weeks. Hepatic pathology is assessed using hematoxylin-eosin staining. Gut microbiota of the cecum are profiled using 16S rDNA gene sequencing and the levels of BAs in serum, colon contents, and feces are measured using ultra-performance liquid chromatography-tandem mass spectrometry. Results indicate that IF significantly decreases murine body weight, insulin resistance, hepatic steatosis, ballooning, and lobular inflammation. IF reshapes the gut microbiota, reduces the accumulation of serum BAs, and increases total colonic and fecal BAs. Moreover, IF increases the expression of cholesterol 7α-hydroxylase 1 in liver, but decreases the expressions of both farnesoid-X-receptor and fibroblast growth factor 15 in the ileum.

CONCLUSION

IF alleviates NASH by regulating bile acid metabolism and promoting fecal bile acid excretion.

Causal associations between human gut microbiota and cholelithiasis: a mendelian randomization study

Background

There was some evidence that gut microbiota was closely related to cholelithiasis, but the causal relationship between them remained unclear. In this study, we try to use Two-sample Mendelian randomization (MR) to clarify the potential causal relationship between gut microbiota and cholelithiasis.

Methods

Summary Genome-Wide Association Studies (GWAS) statistical data for gut microbiota was obtained from MiBioGen, and the data of cholelithiasis was obtained from UK Biobank (UKB). Two-sample MR analyses were performed to assess causalities between gut microbiota and cholelithiasis mainly using the inverse-variance weighted (IVW) method. Sensitivity analyses were used to determine the robustness of the MR results. Reverse MR analyses were performed to examine the reverse causal association.

Results

Our research results, based primarily on the IVW method, support the existence of a causal relationship between nine gut microbial taxa and cholelithiasis. We observed a positive association between Genus Butyrivibrio (p=0.032), Genus Lachnospiraceae_UCG_001 (p=0.015), Genus Ruminococcaceae_NK4A214_group (p=0.003), Genus Ruminococcaceae_UCG_011 (p=0.010) and cholelithiasis, while Order Rhodospirillales (p=0.031), Genus Actinomyces (p=0.010), Genus Phascolarctobacterium (p=0.036), Genus Rikenellaceae_RC9_gutgroup (p=0.023), Genus Ruminococcaceae_UCG_013 (p=0.022) may be associated with a reduced risk of cholelithiasis. We did not find a reverse causal relationship between cholelithiasis and 9 specific gut microbial taxa.

Conclusions

This is the first mendelian randomization study to explore the causalities between specific gut microbiota taxa and cholelithiasis, which may provide new ideas and a theoretical basis for the prevention and treatment of cholelithiasis in the future.

Coffee by-products: An underexplored source of prebiotic ingredients

Consumers' demand for foods with high nutritional value and health benefits has fueled the development of prebiotic foods. In coffee industry, cherries transformation into roasted beans generates a large amount of waste/by-products (pulp/husks, mucilage, parchment, defective beans, silverskin and spent coffee grounds) that usually end up in landfills. The possibility to use coffee by-products as relevant sources of prebiotic ingredients is herein ascertained. As a prelude to this discussion, an overview of pertinent literature on prebiotic action was conducted, including on biotransformation of prebiotics, gut microbiota, and metabolites. Existing research indicates that coffee by-products contain significant levels of dietary fiber and other components that can improve gut health by stimulating beneficial bacteria in the colon, making them excellent candidates for prebiotic ingredients. Oligosaccharides from coffee by-products have lower digestibility than inulin and can be fermented by gut microbiota into functional metabolites, such as short-chain fatty acids. Depending on the concentration, melanoidins and chlorogenic acids may also have prebiotic action. Nevertheless, there is still a lack of in vivo studies to validate such findings in vitro. This review shows how coffee by-products can be interesting for the development of functional foods, contributing to sustainability, circular economy, food security, and health.

The gut microbiota: A new perspective for tertiary prevention of hepatobiliary and gallbladder diseases

The gut microbiota is a complex ecosystem that has coevolved with the human body for hundreds of millions of years. In the past 30 years, with the progress of gene sequencing and omics technology, the research related to gut microbiota has developed rapidly especially in the field of digestive system diseases and systemic metabolic diseases. Mechanical, biological, immune, and other factors make the intestinal flora form a close bidirectional connection with the liver and gallbladder, which can be called the "gut-liver-biliary axis." Liver and gallbladder, as internal organs of the peritoneum, suffer from insidious onset, which are not easy to detect. The diagnosis is often made through laboratory chemical tests and imaging methods, and intervention measures are usually taken only when organic lesions have occurred. At this time, some people may have entered the irreversible stage of disease development. We reviewed the literature describing the role of intestinal flora in the pathogenesis and biotherapy of hepatobiliary diseases in the past 3-5 years, including the dynamic changes of intestinal flora at different stages of the disease, as well as the signaling pathways involved in intestinal flora and its metabolites, etc. After summarizing the above contents, we hope to highlight the potential of intestinal flora as a new clinical target for early prevention, early diagnosis, timely treatment and prognosis of hepatobiliary diseases. GRAPHICAL ABSTRACT.

FXR Signaling-Mediated Bile Acid Metabolism Is Critical for Alleviation of Cholesterol Gallstones by Lactobacillus Strains

Cholesterol gallstone (CGS) disease is characterized by an imbalance in bile acid (BA) metabolism and is closely associated with gut microbiota disorders. However, the role and mechanism by which probiotics targeting the gut microbiota attenuate cholesterol gallstones are still unknown. In this study, Limosilactobacillus reuteri strain CGMCC 17942 and Lactiplantibacillus plantarum strain CGMCC 14407 were individually administered to lithogenic-diet (LD)-fed mice for 8 weeks. Both Lactobacillus strains significantly reduced LD-induced gallstones, hepatic steatosis, and hyperlipidemia. These strains modulated BA profiles in the serum and liver, which may be responsible for the activation of farnesoid X receptor (FXR). At the molecular level, L. reuteri and L. plantarum increased ileal fibroblast growth factor 15 (FGF15) and hepatic fibroblast growth factor receptor 4 (FGFR4) and small heterodimer partner (SHP). Subsequently, hepatic cholesterol 7α-hydroxylase (CYP7A1) and oxysterol 7α-hydroxylase (CYP7B1) were inhibited. Moreover, the two strains enhanced BA transport by increasing the levels of hepatic multidrug resistance-associated protein homologs 3 and 4 (Mrp3/4), hepatic multidrug resistance protein 2 (Mdr2), and the bile salt export pump (BSEP). In addition, both L. reuteri and L. plantarum reduced LD-associated gut microbiota dysbiosis. L. reuteri increased the relative abundance of Muribaculaceae, while L. plantarum increased that of Akkermansia. The changed gut microbiota was significantly negatively correlated with the incidence of cholesterol gallstones and the FXR-antagonistic BAs in the liver and serum and with the FXR signaling pathways. Furthermore, the protective effects of the two strains were abolished by both global and intestine-specific FXR antagonists. These findings suggest that Lactobacillus might relieve CGS through the FXR signaling pathways.

IMPORTANCE Cholesterol gallstone (CGS) disease is prevalent worldwide. None of the medical options for prevention and treatment of CGS disease are recommended, and surgical management has a high rate of recurrence. It has been reported that the factors involved in metabolic syndrome are highly connected with CGS formation. While remodeling of dysbiosis of the gut microbiome during improvement of metabolic syndrome has been well studied, less is known about prevention of CGS formation after regulating the gut microbiome. We used the lithogenic diet (LD) to induce an experimental CGS model in C57BL/6J mice to investigate protection against CGS formation by Limosilactobacillus reuteri strain CGMCC 17942 and Lactiplantibacillus plantarum strain CGMCC 14407. We found that these L. reuteri and L. plantarum strains altered the bile acid composition in mice and improved the dysbiosis of the gut microbiome. These two Lactobacillus strains prevented CGS formation by fully activating the hepatic and ileal FXR signaling pathways. They could be a promising therapeutic strategy for treating CGS or preventing its recurrence.

Si-Wu-Tang ameliorates fibrotic liver injury via modulating intestinal microbiota and bile acid homeostasis

Background

Fibrotic liver injury is a progressive scarring event, which may permanently affect liver function and progress into devastating end-stage liver diseases due to the absence of effective therapies. Si-Wu-Tang (SWT), a traditional Chinese medicine formula used in clinic to treat gynecological disorders for centuries, has been investigated in recent preliminary findings for its role in alleviating chronic liver diseases. Here we aim to elucidate the therapeutic effects and possible mechanisms of SWT against fibrotic liver injury.

Methods

UHPLC-MS/MS was performed to investigate the chemical characterization of SWT. After intragastrically administered with carbon tetrachloride (CCl₄) every 3 days for 1-week, C57BL/6 mice were orally administered with SWT (5.2, 10.4 and 20.8 g/kg) once daily for 3 weeks along with CCl₄ challenge. Liver function was determined by the measurement of serum biomarkers, hematoxylin and eosin (H&E) and Masson’s trichrome staining. Intestinal inflammatory infiltration and the disruption of intestinal barrier were examined by H&E and E-cadherin immunohistochemical staining. The microbial composition of intestinal content was determined by 16S rRNA sequencing. Serum bile acids (BAs) profiling was analyzed by LC–MS/MS. Simultaneously, the expression of genes of interest was determined by qPCR and western blot.

Results

SWT exhibited remarkable therapeutic effects on CCl₄-induced liver fibrosis, as indicated by improved collagen accumulation in livers, intestinal barrier injury and hepatic and intestinal inflammatory response. Results of 16S rRNA sequencing revealed that SWT treatment strikingly restructured intestinal microbiota in fibrotic mice by increasing the relative abundances of Bacteroides and Lachnoclostridium and decreasing the relative abundances of Alistipes and Rikenellaceae. UHPLC-MS/MS data suggested that SWT altered the composition of BAs in circulation as evidenced by increased unconjugated BAs like cholic acid and chenodeoxycholic acid but decreased conjugated BAs including taurocholic acid and taurodeoxycholic acid, compared to that in CCl₄ mice. Notably, SWT efficiently improved the imbalance of BA homeostasis in livers caused by CCl₄ via activating farnesoid X receptor (FXR)-fibroblast growth factor 15 enterohepatic and FXR-small heterodimer partner hepatic pathways.

Conclusion

SWT decreased inflammatory response, reconstructed gut microbiota-mediated BA homeostasis as well as activated FXR pathways, which eventually protected against CCl₄-induced fibrotic liver injury.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-021-00524-0.