Serum Bile Acid Profiles Improve Clinical Prediction of Nonalcoholic Fatty Liver in T2DM patients

Bile Acids as Emerging Players at the Intersection of Steatotic Liver Disease and Cardiovascular Diseases

Affecting approximately 25% of the global population, steatotic liver disease (SLD) poses a significant health concern. SLD ranges from simple steatosis to metabolic dysfunction-associated steatohepatitis and fibrosis with a risk of severe liver complications such as cirrhosis and hepatocellular carcinoma. SLD is associated with obesity, atherogenic dyslipidaemia, and insulin resistance, increasing cardiovascular risks. As such, identifying SLD is vital for cardiovascular disease (CVD) prevention and treatment. Bile acids (BAs) have critical roles in lipid digestion and are signalling molecules regulating glucose and lipid metabolism and influencing gut microbiota balance. BAs have been identified as critical mediators in cardiovascular health, influencing vascular tone, cholesterol homeostasis, and inflammatory responses. The cardio-protective or harmful effects of BAs depend on their concentration and composition in circulation. The effects of certain BAs occur through the activation of a group of receptors, which reduce atherosclerosis and modulate cardiac functions. Thus, manipulating BA receptors could offer new avenues for treating not only liver diseases but also CVDs linked to metabolic dysfunctions. In conclusion, this review discusses the intricate interplay between BAs, metabolic pathways, and hepatic and extrahepatic diseases. We also highlight the necessity for further research to improve our understanding of how modifying BA characteristics affects or ameliorates disease.

Serum bile acid and unsaturated fatty acid profiles of non-alcoholic fatty liver disease in type 2 diabetic patients

BACKGROUND

The understanding of bile acid (BA) and unsaturated fatty acid (UFA) profiles, as well as their dysregulation, remains elusive in individuals with type 2 diabetes mellitus (T2DM) coexisting with non-alcoholic fatty liver disease (NAFLD). Investigating these metabolites could offer valuable insights into the pathophy-siology of NAFLD in T2DM.

AIM

To identify potential metabolite biomarkers capable of distinguishing between NAFLD and T2DM.

METHODS

A training model was developed involving 399 participants, comprising 113 healthy controls (HCs), 134 individuals with T2DM without NAFLD, and 152 individuals with T2DM and NAFLD. External validation encompassed 172 participants. NAFLD patients were divided based on liver fibrosis scores. The analytical approach employed univariate testing, orthogonal partial least squares-discriminant analysis, logistic regression, receiver operating characteristic curve analysis, and decision curve analysis to pinpoint and assess the diagnostic value of serum biomarkers.

RESULTS

Compared to HCs, both T2DM and NAFLD groups exhibited diminished levels of specific BAs. In UFAs, particular acids exhibited a positive correlation with NAFLD risk in T2DM, while the ω-6:ω-3 UFA ratio demonstrated a negative correlation. Levels of α-linolenic acid and γ-linolenic acid were linked to significant liver fibrosis in NAFLD. The validation cohort substantiated the predictive efficacy of these biomarkers for assessing NAFLD risk in T2DM patients.

CONCLUSION

This study underscores the connection between altered BA and UFA profiles and the presence of NAFLD in individuals with T2DM, proposing their potential as biomarkers in the pathogenesis of NAFLD.

Isomers-oriented separation of forty-five plasma bile acids with liquid chromatography-tandem mass spectrometry

Some bile acids (BAs) were considered as biomarkers or have therapeutical effect on metabolic diseases. However, due to the existence of isomers and limitations in sensitivity, simultaneous quantification of multiple BAs remains a challenge. The aim of this study is to establish an accurate and sensitive method for the determination of multiple BAs with similar polarity. A LC-MS/MS analytical method capable of quantifying forty-five BAs simultaneously using nine stable isotope internal standards was developed and fully validated based on key isomers-oriented separation strategy. The method was further applied to analyze plasma samples to describe the dynamic profile of BAs after high glucose intake. The chromatography and mass spectrum conditions were optimized to enable the accurate quantification of forty-five BAs, while ensuring the lower limit of quantification between 0.05-10 ng/mL. The results of system suitability, linearity, dilution integrity, accuracy and precision demonstrated the good quantitative capacity and robustness of the method. A total of thirty-five BAs were quantified in plasma samples from twelve healthy Chinese individuals. The established method featured superior sensitivity and better separation efficiency compared to previous studies. Meanwhile, BAs exhibited correlations with glucose and insulin, suggesting their potential as biomarkers for metabolic disorders.

Probiotic Mixture Ameliorates a Diet-Induced MASLD/MASH Murine Model through the Regulation of Hepatic Lipid Metabolism and the Gut Microbiome

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent metabolic disease that has no effective treatment. Our proprietary probiotic mixture, Prohep, has been proven in a previous study to be helpful in reducing hepatocellular carcinoma (HCC) in vivo. However, its prospective benefits on the treatment of other liver diseases such as MASLD, which is one of the major risk factors in the development of HCC, are unclear. To investigate the potential of Prohep in modulating the development and progression of MASLD, we first explored the effect of Prohep supplementation via voluntary intake in a high-fat diet (HFD)-induced MASLD/metabolic dysfunction-associated steatohepatitis (MASH) murine model. Our results indicated that Prohep alleviated HFD-induced liver steatosis and reduced excessive hepatic lipid accumulation and improved the plasma lipid profile when compared with HFD-fed control mice through suppressing hepatic de novo lipogenesis and cholesterol biosynthesis gene expressions. In addition, Prohep was able to modulate the gut microbiome, modify the bile acid (BA) profile, and elevate fecal short-chain fatty acid (SCFA) levels. Next, in a prolonged HFD-feeding MASLD/MASH model, we observed the effectiveness of Prohep in preventing the transition from MASLD to MASH via amelioration in hepatic steatosis, inflammation, and fibrosis. Taken together, Prohep could ameliorate HFD-induced MASLD and control the MASLD-to-MASH progression in mice. Our findings provide distinctive insights into the development of novel microbial therapy for the management of MASLD and MASH.

Tomatidine ameliorates high-fat-diet/streptozocin (HFD/STZ)-induced type 2 diabetes mellitus in mice

OBJECTIVE

To investigate the effects of tomatidine (Td) on the progression of type 2 diabetes mellitus (T2DM) in mice and uncover the mechanism.

METHODS

T2DM mice model was induced by high-fat diet (HFD) and intrabitoneal injection of streptozotocin (STZ). The mice were grouped as follows: 1, control; 2, T2D; 3, T2D + tomatidine (5 mg/kg); 4, T2D + tomatidine (10 mg/kg); 5, T2D + tomatidine (20 mg/kg). Fasting blood glucose was detected by glucose metre and fasting insulin was detected by the kit to determine the effect of Td on T2DM mice. ELISA, qPCR, and Immunoblot assays were performed to detect the effects of Td on the hepatic glucose homeostasis and inflammation of mice. Immunoblot assays further confirmed the mechanism.

RESULTS

Td improved blood glucose and insulin resistance in T2DM mice. In addition, Td improved liver function and lipid metabolism disorder in T2DM mice. Td also affected the liver glucose homeostasis related genes in T2DM mice. Td alleviated serum inflammation in T2DM mice. We further found that Td activated AMPK pathway, therefore ameliorating T2DM.

CONCLUSION

Td ameliorated HFD/STZ-induced T2DM in mice, suggesting that it could serve as a drug of T2DM.

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.

Alterations in Circulating Bile Acids in Metabolic Dysfunction-Associated Steatotic Liver Disease: A Systematic Review and Meta-Analysis

Background: Previous studies have suggested that bile acids (BAs) may participate in the development and/or progression of metabolic dysfunction-associated steatotic liver disease (MASLD). The present study aimed to define whether specific BA molecular species are selectively associated with MASLD development, disease severity, or geographic region. Methods: We comprehensively identified all eligible studies reporting circulating BAs in both MASLD patients and healthy controls through 30 July 2023. The pooled results were expressed as the standard mean difference (SMD) and 95% confidence interval (CI). Subgroup, sensitivity, and meta-regression analyses were performed to address heterogeneity. Results: Nineteen studies with 154,807 individuals were included. Meta-analysis results showed that total BA levels in MASLD patients were higher than those in healthy controls (SMD = 1.03, 95% CI: 0.63-1.42). When total BAs were divided into unconjugated and conjugated BAs or primary and secondary BAs, the pooled results were consistent with the overall estimates except for secondary BAs. Furthermore, we examined each individual BA and found that 9 of the 15 BAs were increased in MASLD patients, especially ursodeoxycholic acids (UDCA), taurococholic acid (TCA), chenodeoxycholic acids (CDCA), taurochenodeoxycholic acids (TCDCA), and glycocholic acids (GCA). Subgroup analysis revealed that different geographic regions or disease severities led to diverse BA profiles. Notably, TCA, taurodeoxycholic acid (TDCA), taurolithocholic acids (TLCA), and glycolithocholic acids (GLCA) showed a potential ability to differentiate metabolic dysfunction-associated steatohepatitis (MASH) (all p < 0.05). Conclusions: An altered profile of circulating BAs was shown in MASLD patients, providing potential targets for the diagnosis and treatment of MASLD.

A screening strategy for bioactive components of Bu-Zhong-Yi-Qi-Tang regulating spleen-qi deficiency based on "endobiotics-targets-xenobiotics" association network

ETHNOPHARMACOLOGICAL RELEVANCE

Bu-Zhong-Yi-Qi-Tang is a famous traditional Chinese medicine formula that has been prevalent in China for over 700 years to treat spleen-qi deficiency related diseases, such as gastrointestinal and respiratory disorders. However, the bioactive components responsible for regulating spleen-qi deficiency remain unclear and have puzzled many researchers.

AIM OF THE STUDY

The current study focuses on efficacy evaluation of regulating spleen-qi deficiency and screening the bioactive components of Bu-Zhong-Yi-Qi-Tang.

MATERIALS AND METHODS

The effects of Bu-Zhong-Yi-Qi-Tang were evaluated through blood routine examination, immune organ index, and biochemical analysis. Metabolomics was utilized to analyze the potential endogenous biomarkers (endobiotics) in the plasma, and the prototypes (xenobiotics) of Bu-Zhong-Yi-Qi-Tang in the bio-samples were characterized using ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. Then, these endobiotics were used as "bait" to predict targets based on network pharmacology and to screen potential bioactive components from the absorbed prototypes in the plasma by constructing an "endobiotics-targets-xenobiotics" association network. Further, the anti-inflammatory activities of representative compounds (calycosin and nobiletin) were validated through poly(I:C)-induced pulmonary inflammation mice model.

RESULTS

Bu-Zhong-Yi-Qi-Tang exhibited immunomodulatory and anti-inflammatory activities in spleen-qi deficiency rat, as supported by the observation of increased levels of D-xylose and gastrin in serum, an increase in the thymus index and number of lymphocytes in blood, as well as a reduction in the level of IL-6 in bronchoalveolar lavage fluid. Furthermore, plasma metabolomic analysis revealed a total of 36 Bu-Zhong-Yi-Qi-Tang related endobiotics, which were mainly enriched in primary bile acids biosynthesis, the metabolism of linoleic acid, and the metabolism of phenylalanine pathways. Meanwhile, 95 xenobiotics were characterized in plasma, urine, small intestinal contents, and tissues of spleen-qi deficiency rat after Bu-Zhong-Yi-Qi-Tang treatment. Using an integrated association network, six potential bioactive components of Bu-Zhong-Yi-Qi-Tang were screened. Among them, calycosin was found to significantly reduce the levels of IL-6 and TNF-α in the bronchoalveolar lavage fluid, increase the number of lymphocytes, while nobiletin dramatically decreased the levels of CXCL10, TNF-α, GM-CSF, and IL-6.

CONCLUSION

Our study proposed an available strategy for screening bioactive components of BYZQT regulating spleen-qi deficiency based on "endobiotics-targets-xenobiotics" association network.

Serum Bile Acid Metabolites Predict the Therapeutic Effect of Mesalazine in Patients with Ulcerative Colitis

Ulcerative colitis (UC) is a systematic chronic disease characterized by insufficient intestinal absorption, and mesalazine is a common medical treatment. In the present study, 20 normal healthy controls (NC group), 10 unmedicated UC patients (UC group), and 20 mesalazine-responsive and 20 mesalazine-nonresponsive UC patients were recruited. A total of 42 serum BA metabolites, including 8 primary bile acids and 34 secondary bile acids (SBAs), were quantitatively measured. Compared with the NC group, serum SBAs in the UC patients were significantly lower but increased after mesalazine therapy. Differences in the serum TDCA, DCA, GDCA-3S, 12-keto LCA, and GCDCA-3S metabolites were found between the UC and NC groups, with AUC values of 0.777, 0.800, 0.815, 0.775, and 0.740, respectively. Furthermore, we identified 12-keto LCA as a specific BA marker of UC and BA biomarkers of mesalazine responsiveness. It was concluded that serum SBAs were decreased in UC patients, and TDCA, DCA, GDCA-3S, 12-keto LCA, and GCDCA-3S might aid in the diagnosis of UC. The abundance of SBAs increased after the mesalazine therapy, and serum 12-keto LCA was identified as an alternative invasive biomarker associated with UC diagnosis and therapeutic response, thereby providing a new approach for the prediction of response to mesalazine therapy in UC patients.

The role of bile acid metabolism in the occurrence and development of NAFLD

Non-alcoholic fatty liver disease (NAFLD) has become one of the important causes of cirrhosis and liver cancer, resulting in a huge medical burden worldwide. Currently, effective non-invasive diagnostic indicators and drugs for NAFLD are still lacking. With the development of metabolomics technology, the changes in metabolites during the development of NAFLD have been gradually revealed. Bile acid (BA) is the main endpoint of cholesterol metabolism in the body. In addition, it also acts as a signaling factor to regulate metabolism and inflammation in the body through the farnesyl X receptor and G protein-coupled BA receptor. Studies have shown that BA metabolism is associated with the development of NAFLD, but a large number of animal and clinical studies are still needed. BA homeostasis is maintained through multiple negative feedback loops and the enterohepatic circulation of BA. Recently, treatment of NAFLD by interfering with BA synthesis and metabolism has become a new research direction. Here, we review the changes in BA metabolism and its regulatory mechanisms during the development of NAFLD and describe the potential of studies exploring novel non-invasive diagnostic indicators and therapeutic targets for NAFLD based on BA metabolism.

Liver-derived metabolites as signaling molecules in fatty liver disease

Excessive fat accumulation in the liver has become a major health threat worldwide. Unresolved fat deposition in the liver can go undetected until it develops into fatty liver disease, followed by steatohepatitis, fibrosis, cirrhosis, and eventually hepatocellular carcinoma. Lipid deposition in the liver is governed by complex communication, primarily between metabolic organs. This can be mediated by hormones, organokines, and also, as has been more recently discovered, metabolites. Although how metabolites from peripheral organs affect the liver is well documented, the effect of metabolic players released from the liver during the development of fatty liver disease or associated comorbidities needs further attention. Here we focus on interorgan crosstalk based on metabolites released from the liver and how these molecules act as signaling molecules in peripheral tissues. Due to the liver's specific role, we are covering lipid and bile mechanism-derived metabolites. We also discuss the high sucrose intake associated with uric acid release from the liver. Excessive fat deposition in the liver during fatty liver disease development reflects disrupted metabolic processes. As a response, the liver secretes a variety of signaling molecules as well as metabolites which act as a footprint of the metabolic disruption. In the coming years, the reciprocal exchange of metabolites between the liver and other metabolic organs will gain further importance and will help to better understand the development of fatty liver disease and associated diseases.

Gut-Liver Axis and Non-Alcoholic Fatty Liver Disease: A Vicious Circle of Dysfunctions Orchestrated by the Gut Microbiome

Non-alcoholic fatty liver disease (NAFLD) is a prevalent, multifactorial, and poorly understood liver disease with an increasing incidence worldwide. NAFLD is typically asymptomatic and coupled with other symptoms of metabolic syndrome. The prevalence of NAFLD is rising in tandem with the prevalence of obesity. In the Western hemisphere, NAFLD is one of the most prevalent causes of liver disease and liver transplantation. Recent research suggests that gut microbiome dysbiosis may play a significant role in the pathogenesis of NAFLD by dysregulating the gut-liver axis. The so-called "gut-liver axis" refers to the communication and feedback loop between the digestive system and the liver. Several pathological mechanisms characterized the alteration of the gut-liver axis, such as the impairment of the gut barrier and the increase of the intestinal permeability which result in endotoxemia and inflammation, and changes in bile acid profiles and metabolite levels produced by the gut microbiome. This review will explore the role of gut-liver axis disruption, mediated by gut microbiome dysbiosis, on NAFLD development.

Kaempferol attenuates nonalcoholic steatohepatitis by regulating serum and liver bile acid metabolism

Objective: Changes in bile acids (BAs) are increasingly recognized as potential targets for non-alcoholic steatohepatitis (NASH). Kaempferol has been proved to be anti-inflammatory and reduce the disorder of lipid metabolism. In order to analyze the BA profile in NASH mice and determine the predictive biomarkers of kaempferol treatment, serum-targeted metabolomics and liver tissue RNA sequencing (RNA-seq) were carried out.

Design: Six normal control mice (NC group), eight HFD-fed mice (HFD group), and eight kaempferol-treated HFD-fed mice (HFD + KP group) were included in the present study. Ultra-performance liquid chromatography coupled to a tandem mass spectrometry system (UPLC-MS/MS) was used to quantify serum and liver BAs, and RNA-seq was used to quantify liver differentially expressed genes related to BA metabolism.

Results: The serum levels of CA, βMCA, UDCA, and 12-DHCA, as well as ωMCA in both the serum and liver, were significantly decreased in the HFD group compared with those in the NC group, and kaempferol can increase the serum levels of βMCA, UDCA, and ωMCA and the liver level of 12-DHCA. The serum levels of TDCA, THDCA, TUDCA, TDCA/CA, and TDCA/DCA were significantly increased in the HFD group compared with those of the NC group, and kaempferol can decrease them. Furthermore, NASH mice had a higher liver level of total CA%, total CDCA%, primary BAs/secondary BAs, 12α-OH BAs/non-12α-OH Bas, and conjugated BAs/unconjugated BAs, and all decreased after kaempferol treatment. According to the RNA-seq results, we found that compared with the NC group, the mRNA expression of cholesterol-7α-hydroxylase (CYP7A1) in the HFD group was significantly increased, and the mRNA expression of sterol 12α‐hydroxylase (CYP8B1) and multidrug resistance-related protein 3 (MRP3) was significantly decreased, while kaempferol significantly promoted the mRNA expression of mitochondrial sterol 27-hydroxylase (CYP27A1) and Na⁺ -taurocholate cotransporting polypeptide (NTCP).

Conclusion: βMCA, CA, UDCA, 12-DHCA, ωMCA, CDCA, TωMCA, TDCA, THDCA, TCDCA, and TUDCA in the serum, as well as 6,7-diketoLCA, 12-DHCA, and ωMCA in the liver, may be potential biomarkers for kaempferol to improve NASH. HFD-induced NASH may be associated with the increase of CYP7A1 and the decrease of CYP8B1, leading to increased BA synthesis, and the decrease of MRP3 leading to decreased BA synthesis, and kaempferol may alleviate NASH by increasing CYP27A1 and NTCP to enhance BA transport.