Bile acid metabolism and signalling in liver disease

A novel liver-targeted and highly selective fluorescent probe for hepatic hydrogen sulfide detection in the diagnosis of drug-induced liver injury

Drug-induced liver injury (DILI) has emerged as a significant health risk, yet reliable methods of detection at an early stage are in urgent need. Recent researches have highlighted the crucial role of hydrogen sulfide (H2S) in various pathological and physiological processes, with a correlation between its levels and the severity of DILI. We developed a novel fluorescent probe H2S-YL for the precise detection of liver H2S fluctuations in DILI, and the liver in situ accumulation capacity of H2S-YL has been significantly enhanced by incorporating a liver-targeting cholic acid moiety into its skeleton. Furthermore, H2S-YL displays exceptional selectivity, good sensitivity and responds rapidly toward H2S within 3 min, thereby enabling precise detection of subtle hepatic H2S fluctuations capability essential for accurately assessing the severity of DILI. Subsequently, H2S-YL was employed to assess the hepatoprotective effects of natural constituents derived from traditional Chinese medicine, via monitoring H2S levels both in cells and in vivo. These results demonstrate that H2S-YL serves as a powerful tool for visualizing pathological hepatic H2S fluctuations, thereby enabling the assessment of DILI severity and the efficacy of hepatoprotective natural constituents.

Critical Role of Cholic Acid in the Development of iHFC Diet-induced MASH in TSNO Mice

A high-fat/cholesterol/cholate-based (iHFC) diet induces pathological changes in Tsumura-Suzuki non-obese (TSNO) mice, resembling human metabolic dysfunction associated steatohepatitis (MASH), along with advanced liver fibrosis. In this study, we investigated the role of cholic acid (CA) in the development of iHFC diet-induced MASH development. In mice receiving an iHFC diet without CA (CA(-) iHFC diet), both lobular inflammation and fibrosis progression in the liver were attenuated compared to those on the standard iHFC diet. Notably, hepatocyte ballooning was significantly improved in the CA(-) iHFC diet group. The expression levels of genes associated with inflammation and fibrosis were lower in the livers of CA(-) iHFC diet-fed mice compared to those fed the iHFC diet. Furthermore, there were no significant changes in the proportion and number of monocyte-derived macrophages in the livers of CA(-) iHFC diet-fed mice relative to those in the ND (normal diet)-fed group. The co-localization of CD11c+ macrophages with collagen fibers in the livers of CA(-) iHFC diet-fed mice did not significantly differ from that of the ND-fed group. Moreover, the CA(-) iHFC-fed mice exhibited a distinct microbial composition relative to both ND- and iHFC-fed mice. Finally, the increase in deoxycholic acid in fecal samples and the reduced hepatic expression of Cyp27a1 and Cyp7a1 induced by the iHFC diet were less in the CA(-) iHFC-fed group. These results suggest that CA modulates iHFC diet-induced MASH development by influencing the accumulation of monocyte-derived macrophages in the liver and shaping the gut microbiota composition and bile acid profile.

Ileal FXR Knockdown Ameliorates MASLD Progression in Rats via Modulating Bile Acid Metabolism Mediated by Gut Microbiota

BACKGROUND AND AIM

Metabolic dysfunction associated steatotic liver disease (MASLD) is the predominant cause of chronic liver disease, with dysregulation of bile acid (BA) metabolism and intestinal microbiota being intricately associated with MASLD progression. In this study, we investigated the role of ileal FXR in MASLD progression and BA metabolism in portal blood.

METHODS

Sprague-Dawley rats were fed a typical western diet for 20 weeks, followed by local perfusion of AAV2-shNr1h4 to downregulate Nr1h4 expression in ileum tissue. To investigate the effect of ileal FXR on BA reabsorption and gut microbiota, portal blood and cecal fecal samples were collected from MASLD rats injected with AAV2-Ctrl or AAV2-shNr1h4 for metabolomics targeting BAs and 16S rRNA sequencing analysis.

RESULTS

Our results showed that hepatic steatosis and inflammation were alleviated, whereas the reabsorption of secondary BAs and unconjugated BAs into the portal blood was enhanced when ileal FXR was knocked down. Furthermore, knockdown of ileal FXR resulted in a significant alteration in composition of the cecal microbiota, characterized by an increasing abundance of microbes involved in secondary BA production, including Escherichia, Adlercreutzia, Eubacterium, and Clostridium.

CONCLUSION

These findings suggest that downregulation of ileal FXR ameliorates the progression of MASLD in rats by modulating BA metabolism mediated by the gut microbiota, indicating that ileal FXR might be a potential therapeutic target for the treatment of MASLD.

Hepatoprotective effects of dandelion against AFB1-induced liver injury are associated with activation of bile acid-FXR signaling in chicks

This study aimed to investigate the protective effects of dandelion against AFB1-induced hepatotoxicity through the regulation of the FXR signaling pathway in chicks. A total of 144 one-day-old male broilers were randomly assigned to three groups and received a basal diet (BD), and BD supplemented with 0.5 mg/kg of AFB1 or 0.5 mg/kg AFB1 with 0.4 % dandelion for 3 weeks. The results showed that the AFB1 treatment caused liver injury and decreased the concentrations of albumin and alkaline phosphatase in serum and increased the total bile acid concentration in serum and liver. Dietary AFB1 supplementation also induced hepatocyte swelling, necrosis, neutrophils infiltration and lipid deposition in the liver. Notably, dietary dandelion supplementation alleviated these alterations induced by AFB1. Additionally, dietary dandelion supplementation alleviated AFB1-induced changes in ileum microbiota and decreased the abundance of Lactobacillus, L. vaginalis, and L. acidophilus compared to the AFB1 treatment. Furthermore, AFB1 downregulated Baat, Ntcp, Acc, FXR, SHP, and SREBP-1c expression, and upregulated Cyp8b1, Bacs, Fas, Pparα, Lxrα and CYP7A1 expression in liver. Meanwhile, AFB1 also downregulated Fgf19, Ostα, Ostβ and FXR expression and upregulated SHP expression in the ileum. Conclusively, dietary dandelion supplementation protected broilers from AFB1-induced hepatotoxicity, potentially due to the activation of bile acid-FXR signaling pathway.

Cholestasis in Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) is a leading cause of liver-related morbidity and mortality. ALD covers a spectrum of diseases, ranging from mild and reversible hepatic steatosis to the development of fibrosis, cirrhosis, and alcohol-associated hepatitis (AH). AH is marked by a rapid onset of jaundice and elevated serum levels of aspartate aminotransferase in individuals with heavy alcohol use. It can progress to acute-on-chronic liver failure, with a mortality rate of approximately 30% within the first month. Unfortunately, treatment options for AH are still limited. Cholestasis refers to an impairment in bile formation or flow, leading to clinical symptoms, such as fatigue, pruritus, and jaundice. Cholestasis and biliary dysfunction are commonly seen in patients with AH and can significantly worsen the prognosis. However, the mechanisms and roles of cholestasis in ALD are not yet fully understood. In this review, we will summarize recent findings and explore the potential roles and mechanisms of cholestasis in the progression of ALD.

A preliminary study of serum metabolomic profiling in male patients with acute brucellosis

Brucellosis is a significant zoonotic disease that may lead to metabolic profile changes, which remain insufficiently studied. This study utilized an ultra-high performance liquid chromatography coupled with Q Exactive-Orbitrap mass spectrometry (UHPLC-QExactive-Orbitrap MS/MS) to investigate serum samples of acute brucellosis in 32 male patients against 32 well-matched healthy controls. The results revealed nine differential metabolites that correlated with human acute brucellosis, all showing increased levels, except cis-4-hydroxy-D-proline, inosine, hypoxanthine and azelaic acid. These differential metabolites were predominantly involved in metabolic pathways, such as primary bile acid biosynthesis, purine metabolism, taurine and hypotaurine metabolism, and d-amino acid metabolism. This study identified potential metabolite biomarkers of acute brucellosis and laid the foundation for its early diagnosis and prognostic assessment, thus helping to prevent the chronicity of acute brucellosis.

Characteristics of serum bile acid profiles among individuals with metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) has become the predominant chronic liver condition globally. Bile acid (BA) metabolism contributes significantly to MASLD progression. In this multicenter clinical study, we aimed to characterize serum BA profiles in patients with MASLD and identify specific alterations compared to healthy controls.

METHODS

All MASLD cases were sourced from the gastroenterology outpatient departments of Shanghai Baoshan Hospital of Integrated Chinese and Western Medicine, Shanghai Baoshan District Songnan Community Health Service Center, and Lianyungang Oriental Hospital between June 2015 and December 2019. The data were analyzed using SPSS version 26.0, with a p-value of less than 0.05 considered significant.

RESULTS

A total of 215 participants (35.3% women) with MASLD and 49 controls (44.9% women), aged 18-65 years, were included. MASLD patients showed higher levels of serum total BA (TBA), cholic acid (CA), chenodeoxycholic acid (CDCA), and ursodeoxycholic acid (UDCA) (p < 0.05, p < 0.01) when compared to controls. Furthermore, women patients with MASLD demonstrated notably higher levels of lithocholic acid (LCA), glycolithocholic acid (GLCA), and taurolithocholic acid (TLCA) than men patients with MASLD (p < 0.025, p < 0.01). Compared to women, men exhibited a higher proportion of primary to secondary BAs. Additionally, in men patients with MASLD, the serum concentrations of CA, CDCA, glycocholic acid (GCA), glycochenodeoxycholic acid (GCDCA), and taurochenodeoxycholic acid (TCDCA) exhibited significant negative correlations with ALT levels, while deoxycholic acid (DCA) and TLCA showed negative correlations with BMI.

CONCLUSIONS

Patients with MASLD exhibited notable variations in BA profiles, including sex-specific differences. This study provides corresponding evidence on the association between BAs and MASLD.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, NO: ChiCTR-OOC-15006157, registration date: March 25, 2015.

Gut microbiota Lactobacillus johnsonii alleviates hyperuricemia by modulating intestinal urate and gut microbiota-derived butyrate

BACKGROUND

Gut microbiota are important for uric acid (UA) metabolism within hyperuricemia (HUA); however, the underlying mechanisms of how the gut microbiota regulate intestinal UA metabolism remain unclear. This study aimed to explore the function of the intestine in HUA and to further reveal the possible mechanism.

METHODS

We conducted gut microbiota depletion to validate the role of gut microbiota in UA metabolism. A mouse model of HUA was established, and the gut microbiota and microbiome-derived metabolites were analyzed via 16S RNA gene sequencing and metabolomics analysis. The mechanism of the gut microbiota in HUA was elucidated by in vivo and in vitro experiments.

RESULTS

Antibiotic treatment elevated serum UA, disturbed purine metabolism, and decreased the relative abundance of Lactobacillus. HUA mice had a lower relative abundance of Lactobacillus johnsonii (L. johnsonii) and decreased gut butyrate concentration. Supplementation of L. johnsonii significantly reduces serum UA in hyperuricemia mice by preventing UA synthesis and promoting the excretion of gut purine metabolites. In addition, L. johnsonii enhanced intestinal UA excretion by heightening the urate transporter ABCG2 (adenosine triphosphate-binding cassette transporter, subfamily G, member 2) expression, and increasing the levels of butyrate, which upregulated ABCG2 expression via the Wnt5a/b/β-catenin signaling pathway.

CONCLUSION

Our results suggest that gut microbiota and microbiota-derived metabolites directly regulate gut UA metabolism, highlighting potential applications in the treatment of diet-induced HUA by targeting gut microbiota and its metabolites.

Hesperidin improves cardiac fibrosis induced by β-adrenergic activation through modulation of gut microbiota

Cardiac fibrosis is a prevalent characteristic of various cardiovascular diseases and poses a significant global health challenge. Recent research has established a robust correlation between gut microbiota and cardiovascular diseases. Hesperidin has been shown to possess cardioprotective properties to some extent. Furthermore, studies suggest that hesperidin may enhance overall health by regulating intestinal flora. However, there is a lack of reports regarding the effects of hesperidin on cardiac fibrosis. This study aimed to investigate the mechanisms by which hesperidin ameliorates cardiac fibrosis through the regulation of gut microbiota and associated metabolites. Cardiac fibrosis was induced in C57BL/6 mice via subcutaneous injection of isoproterenol (5 mg/kg per day) for a duration of 7 days. Echocardiography was used to assess cardiac function, while Masson staining, western blot analysis, and real-time polymerase chain reaction were used to evaluate fibrosis-related indicators. Changes in gut microbiota were analyzed through 16S ribosomal RNA gene sequencing. Our findings indicate that hesperidin significantly mitigates cardiac fibrosis in mice. These beneficial effects are associated with improvements in the dysbiosis of intestinal microbiota observed in fibrotic mouse models. The involvement of gut microbiota in cardiac fibrosis was further corroborated by administering hesperidin therapy to mice depleted of gut microbiota. To our knowledge, this study provides the first evidence that the modulation of gut microbiota by hesperidin contributes to improved outcomes in cardiac fibrosis. The use of traditional Chinese medicine to modulate gut microbiota presents a promising strategy for the treatment of cardiac fibrosis. SIGNIFICANCE STATEMENT: The work is extremely interesting because it acts on a frontier of science that relates the influence of the intestinal microbiota with human physiological systems and associated pathologies. This study provides the first evidence that the modulation of gut microbiota by hesperidin contributes to improved outcomes in cardiac fibrosis.

BAAT away liver cancer: conjugated bile acids impair T cell function in hepatocellular carcinoma immunotherapy

In this renaissance era of gene therapy, a new study published by the Susan Kaech lab in Science demonstrates the use of CRISPR-Cas9 technology to selectively deplete conjugated bile acids in the liver by targeting the bile acid-CoA:amino acid N-acyltransferase (Baat) gene to improve responsiveness to immunotherapy. This study highlights the role of conjugated bile acids in impairing intratumoral T cell function by directly accumulating in resident liver T cells and driving mitochondrial dysfunction. Knockout of Baat reduced hepatic conjugated bile acid production, thus improving immunotherapy potency and reducing tumor burden. Subsequently, Baat liver knockout reduced levels of microbially produced secondary bile acids such as lithocholic acid, a known carcinogen and T cell toxin. This study mechanistically links bile acids to liver cancer immunotherapy success, setting the stage for bile acid-based screening approaches and pharmacologic manipulations for improved patient outcomes.

Molecular Landscape and Diagnostic Model of MASH: Transcriptomic, Proteomic, Metabolomic, and Lipidomic Perspectives

Metabolic dysfunction-associated steatohepatitis (MASH), a progressive form of fatty liver disease, presents a significant global health challenge. Despite extensive research, fully elucidating its complex pathogenesis and developing accurate non-invasive diagnostic tools remain key goals. Multi-omics approaches, integrating data from transcriptomics, proteomics, metabolomics, and lipidomics, offer a powerful strategy to achieve these aims. This review summarizes key findings from multi-omics studies in MASH, highlighting their contributions to our understanding of disease mechanisms and the development of improved diagnostic models. Transcriptomic studies have revealed widespread gene dysregulation affecting lipid metabolism, inflammation, and fibrosis, while proteomics has identified altered protein expression patterns and potential biomarkers. Metabolomic and lipidomic analyses have further uncovered significant changes in various metabolites and lipid species, including ceramides, sphingomyelins, phospholipids, and bile acids, underscoring the central role of lipid dysregulation in MASH. These multi-omics findings have been leveraged to develop novel diagnostic models, some incorporating machine learning algorithms, with improved accuracy compared to traditional methods. Further research is needed to validate these findings, explore the complex interplay between different omics layers, and translate these discoveries into clinically useful tools for improved MASH diagnosis and prognosis.

Gut microbiota differences, metabolite changes, and disease intervention during metabolic - dysfunction - related fatty liver progression

In the current era, metabolic dysfunction-associated steatotic liver disease (MASLD) has gradually developed into a major type of chronic liver disease that is widespread globally. Numerous studies have shown that the gut microbiota plays a crucial and indispensable role in the progression of MASLD. Currently, the gut microbiota has become one of the important entry points for the research of this disease. Therefore, the aim of this review is to elaborate on the further associations between the gut microbiota and MASLD, including the changes and differences in the microbiota between the healthy liver and the diseased liver. Meanwhile, considering that metabolic dysfunction-associated fatty liver and metabolic dysfunction-associated steatohepatitis are abnormal pathological states in the development of the disease and that the liver exhibits different degrees of fibrosis (such as mild fibrosis and severe fibrosis) during the disease progression, we also conduct a comparison of the microbiota in these states and use them as markers of disease progression. It reveals the changes in the production and action mechanisms of short-chain fatty acids and bile acids brought about by changes in the gut microbiota, and the impact of lipopolysaccharide from Gram-negative bacteria on the disease. In addition, the regulation of the gut microbiota in disease and the production and inhibition of related disease factors by the use of probiotics (including new-generation probiotics) will be explored, which will help to monitor the disease progression of patients with different gut microbiota compositions in the future and carry out personalized targeted therapies for the gut microbiota. This will achieve important progress in preventing and combating this disease.