Bile acids in glucose metabolism in health and disease

Restoration of intestinal secondary bile acid synthesis: A potential approach to improve pancreatic β cell function in type 1 diabetes

This study investigates the roles of gut microbiome and secondary bile acid dysfunctions in type 1 diabetes (T1D) and explores targeted interventions to address them. It finds that T1D is associated with reduced gut microbial diversity and imbalance favoring harmful bacteria over beneficial ones. Additionally, patients with T1D exhibited impaired secondary bile acid metabolism. Interventions aimed at modulating the gut microbiome and metabolites are safe and improve glycemic control, reduce daily insulin dose, and reduce inflammation. These interventions reshape the gut microbiome toward a healthier state and enhance secondary bile acid production. Responders to the interventions show increased levels of beneficial bacteria and secondary bile acids, along with improved C-peptide responses. Overall, these findings suggest that targeted modulation of the gut microbiome and secondary bile acid metabolism could be a promising therapeutic approach for T1D management. The trial is registered at Chinese Clinical Trial Registry (ChiCTR-ONN-17011279).

The functions of gut microbiota-mediated bile acid metabolism in intestinal immunity

BACKGROUND

Bile acids, derived from cholesterol in the liver, consist a steroidal core. Primary bile acids and secondary bile acids metabolized by the gut microbiota make up the bile acid pool, which modulate nuclear hormone receptors to regulate immunity. Disruptions in the crosstalk between bile acids and the gut flora are intimately associated with the development and course of gastrointestinal inflammation.

AIM OF REVIEW

This review provides an extensive summary of bile acid production, transport and metabolism. It also delves into the impact of bile acid metabolism on the body and explores the involvement of bile acid-microbiota interactions in various disease states. Furthermore, the potential of targeting bile acid signaling as a means to prevent and treat inflammatory bowel disease is proposed.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this review, we primarily address the functions of bile acid-microbiota crosstalk in diseases. Firstly, we summarize bile acid signalling and the factors influencing bile acid metabolism, with highlighting the immune function of microbially conjugated bile acids and the unique roles of different receptors. Subsequently, we emphasize the vital role of bile acids in maintaining a healthy gut microbiota and regulating the intestinal barrier function, energy metabolism and immunity. Finally, we explore differences of bile acid metabolism in different disease states, offering new perspectives on restoring the host's health and the gastrointestinal ecosystem by targeting the gut microbiota-bile acid-bile acid receptor axis.

The Role of Bile Acid in Immune-Mediated Skin Diseases

Immune-mediated skin disorders arise from dysfunctional immune responses, instigating inflammatory dermatoses and a reduced quality of life. The complex pathogenesis likely involves genetic risks, environmental triggers and aberrant immune activation. An emerging body of evidence suggests that bile acid disturbances may critically promote immune pathology in certain skin conditions. Bile acids synthesised from cholesterol regulate nutrient metabolism and immune cell function via nuclear receptors and G protein-coupled receptors (GPCRs). Altered bile acid profiles and receptor expression have been identified in psoriasis, atopic dermatitis (AD) and autoimmune blistering diseases. Disruptions in bile acid signalling affect the inflammatory and metabolic pathways linked to these disorders. Targeting components of the bile acid axis represents a promising therapeutic strategy. This review elucidates the intricate links between bile acid homeostasis and immune dysfunction in inflammatory skin diseases, synthesising evidence that targeting bile acid pathways may unlock innovative therapeutic avenues. This study compiles clinical and experimental data revealing disrupted bile acid signalling and composition in various immune-mediated dermatoses, highlighting the emerging significance of bile acids in cutaneous immune regulation.

The gut microbiota-bile acid-TGR5 axis orchestrates platelet activation and atherothrombosis

Gut microbiota-derived bile acids are crucial in the pathogenesis and treatment of metabolic diseases. However, their impact on platelet activation and thrombosis in coronary artery disease (CAD) remains poorly understood. In this study, we observed reduced serum deoxycholic acid (DCA) in patients with CAD and an underrepresentation of Bacteroides vulgatus in the gut microbiota of patients with CAD, affecting DCA metabolism. We used Takeda G-protein-coupled receptor 5 (TGR5) inhibitors and TGR5 knockout mice to show that DCA inhibited agonist-induced platelet activation and thrombosis by interacting with the platelet TGR5. Oral gavage treatments with DCA, B. vulgatus and stool from healthy individuals suppressed platelet hyperreactivity and thrombosis in atherosclerotic ApoE-/- mice, reduced microvascular thrombosis and protected the heart from myocardial ischemia/reperfusion injury. Here we describe the role of the bile acid DCA in platelet activation and suggest that targeting the gut microbiota and/or altering bile acid metabolism may be beneficial to treat CAD-associated thrombosis.

Crosstalk Between Bile Acids and Intestinal Epithelium: Multidimensional Roles of Farnesoid X Receptor and Takeda G Protein Receptor 5

Bile acids and their corresponding intestinal epithelial receptors, the farnesoid X receptor (FXR), the G protein-coupled bile acid receptor (TGR5), play crucial roles in the physiological and pathological processes of intestinal epithelial cells. These acids and receptors are involved in the regulation of intestinal absorption, signal transduction, cellular proliferation and repair, cellular senescence, energy metabolism, and the modulation of gut microbiota. A comprehensive literature search was conducted using PubMed, employing keywords such as bile acid, bile acid receptor, FXR (nr1h4), TGR5 (gpbar1), intestinal epithelial cells, proliferation, differentiation, senescence, energy metabolism, gut microbiota, inflammatory bowel disease (IBD), colorectal cancer (CRC), and irritable bowel syndrome (IBS), with a focus on publications available in English. This review examines the diverse effects of bile acid signaling and bile receptor pathways on the proliferation, differentiation, senescence, and energy metabolism of intestinal epithelial cells. Additionally, it explores the interactions between bile acids, their receptors, and the microbiota, as well as the implications of these interactions for host health, particularly in relation to prevalent intestinal diseases. Finally, the review highlights the importance of developing highly specific ligands for FXR and TGR5 receptors in the context of metabolic and intestinal disorders.

Understanding the role of Hedgehog signaling pathway and gut dysbiosis in fueling liver cancer

Liver cancer is one of the most prevalent types of cancer worldwide with less than 20% of patients surviving in the past half a decade. Several molecular pathways have been uncovered that may lead to the development of liver cancer but more recently the Hedgehog pathway (HH) and its interactions with the gut microbiota has emerged as an underlying cause of the development of liver cancer. Gut-liver axis is vital to maintaining homeostasis. The HH pathway controls cellular differentiation, proliferation, and apoptosis evasions, its abnormal activation can lead to uncontrolled proliferation of liver cancer stem cells. Additionally, the intricate interplay between HH signaling and the gut microbiota introduces a novel dimension. Recent investigations suggest that potential modulation of HH activity by gut microbiota influence HCC progression. This review explores a crosstalk between HH signaling and the gut microbiota, uncovering intricate mechanisms by which it fuels liver cancer development. This interplay provides insights into gut dysbiosis, HCC etiology and potential therapeutic avenues, highlighting the cooperative role of HH signaling and gut microbiota in shaping the overall HCC landscape.

Synergistic action of cilnidipine and bexarotene in mitigating cholestatic liver damage: role of FXR signaling cascade

Cholestasis, a condition characterized by impaired bile flow, can lead to severe liver damage if left untreated. Current therapeutic options are limited, necessitating the development of novel treatment strategies. This study investigated the synergistic action of cilnidipine, a calcium channel blocker, and bexarotene, a retinoid X receptor (RXR) agonist, in mitigating cholestatic liver damage induced by alpha-naphthyl isothiocyanate (ANIT) in rats. The study aimed to elucidate the role of the farnesoid X receptor (FXR) signaling cascade in the protective effects of the combined treatment. Rats were divided into three groups: a negative control group, an ANIT-treated group, and a group pretreated with cilnidipine and bexarotene before ANIT administration. Biochemical markers of liver function, oxidative stress, and inflammation were assessed, along with histological examination of liver tissue. The expression of genes related to the FXR signaling pathway was also evaluated using quantitative polymerase chain reaction (qPCR). The results demonstrated that pretreatment with cilnidipine and bexarotene significantly attenuated ANIT-induced cholestatic liver damage, as evidenced by improved liver function markers, reduced oxidative stress and inflammation, and ameliorated histological changes. Furthermore, the combined treatment upregulated the expression of FXR and its target genes, suggesting that the protective effects may be mediated through the activation of the FXR signaling cascade. These findings highlight the potential of cilnidipine and bexarotene as a novel therapeutic approach for the management of cholestatic liver disorders and provide insights into the underlying molecular mechanisms involving the FXR signaling pathway.

Endogenous Metabolites in Metabolic Diseases: Pathophysiologic Roles and Therapeutic Implications

Breakthroughs in metabolomics technology have revealed the direct regulatory role of metabolites in physiology and disease. Recent data have highlighted the bioactive metabolites involved in the etiology and prevention and treatment of metabolic diseases such as obesity, nonalcoholic fatty liver disease, type 2 diabetes mellitus, and atherosclerosis. Numerous studies reveal that endogenous metabolites biosynthesized by host organisms or gut microflora regulate metabolic responses and disorders. Lipids, amino acids, and bile acids, as endogenous metabolic modulators, regulate energy metabolism, insulin sensitivity, and immune response through multiple pathways, such as insulin signaling cascade, chemical modifications, and metabolite-macromolecule interactions. Furthermore, the gut microbial metabolites short-chain fatty acids, as signaling regulators have a variety of beneficial impacts in regulating energy metabolic homeostasis. In this review, we will summarize information about the roles of bioactive metabolites in the pathogenesis of many metabolic diseases. Furthermore, we discuss the potential value of metabolites in the promising preventive and therapeutic perspectives of human metabolic diseases.

Gut Microbiota Metabolites and Chronic Diseases: Interactions, Mechanisms, and Therapeutic Strategies

The gut microbiota, shaped by factors such as diet, lifestyle, and genetics, plays a pivotal role in regulating host metabolism, immune function, and overall health. The diversity and balance of the gut microbiota are closely linked to the onset and progression of various chronic diseases. A growing body of evidence has demonstrated that alterations in the composition, function, and metabolites of the gut microbiota are significantly associated with cardiovascular diseases, including hypertension, atherosclerosis, and heart failure; metabolic disorders such as obesity, type 2 diabetes, and metabolic dysfunction-associated steatotic liver disease; and gastrointestinal conditions like inflammatory bowel disease and colorectal cancer. Despite substantial advances in microbiome research, challenges remain in fully elucidating the causal relationships between the gut microbiota and disease, as well as in translating these insights into clinical applications. This review aims to investigate the regulatory pathways via which the gut microbiota affects cardiovascular health, metabolic function, and gastrointestinal disease. Additionally, it highlights emerging strategies for the prevention and treatment of these chronic conditions, focusing on microbiota-targeted therapies and personalized dietary interventions as promising approaches for improving health outcomes.

Ruditapes philippinarum Polysaccharide Alleviates Hyperglycemia by Modulating Gut Microbiota in a Mouse Model of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM), a widespread chronic metabolic disorder, presents a global challenge. Metformin hydrochloride, although widely prescribed, is associated with notable side effects. This study aims to explore safer, more effective alternatives by assessing the impact of Ruditapes philippinarum polysaccharides (RPPs) on glycemic control and modulation of microbiota in T2DM mice. A T2DM mouse model was established through a high-sucrose/high-fat diet and intraperitioneal streptozotocin injection. Glycometabolism indicators, histopathological features, and gut microbiota composition in caecum samples were assessed. Following 4 weeks of RPPs intervention, fasting blood glucose (FBG), glycated serum protein (GSP), area under the curve (AUC) of oral glucose tolerance test (OGTT), total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-c) levels were reduced in T2DM mice, while AKT-1 and GLUT-2 transcription levels were significant increased. Short-chain fatty acids (SCFAs) concentrations notably increased in the RPP-L group compared to the Model group, with improvements also observed in medium-chain fatty acids (MCFAs) and secondary bile acids (SBAs). Regarding gut microbiota, the Firmicutes-to-Bacteroidetes (F/B) ratio in RPP-L was substantially lower than in the Model group. At the genus level, beneficial bacteria, such as Akkermansia, Alloprevotella, Tidjanibacter, and Faecalibaculum demonstrated increased abundance. Correlation analysis identified Muribaculum, Paramuribaculum, Lacrimispora, and Turicibacter as microbial taxa associated with T2DM progression. RPPs significantly alleviated hyperglycemic symptoms in T2DM mice while enhancing the presence of beneficial gut bacteria, leading to a marked improvement in intestinal microbiota composition. This research offers foundational insights for the potential use of R. philippinarum in biomedical and nutraceutical applications.

Hepatic HKDC1 deletion alleviates western diet-induced MASH in mice

The global prevalence of Metabolic Dysfunction-Associated Steatohepatitis (MASH) has been rising sharply, closely mirroring the increasing rates of obesity and metabolic syndrome. MASH exhibits a strong sexual dimorphism where females are affected with more severe forms after menopause. Hexokinase domain-containing protein 1 (HKDC1) has recently been recognized for its role in liver diseases, where its expression is minimal under normal conditions but significantly increases in response to metabolic stressors like obesity and liver injury. This selective upregulation suggests HKDC1's potential specialization in hepatic glucose and lipid dysregulation, linking it closely to the progression of MASH. This study aims to clarify the role of HKDC1 in Western diet-induced MASH in female mice by examining its impact on hepatic glucose and lipid metabolism, offering insights into its potential as a therapeutic target and addressing the need for sex-specific research in liver disease. This study reveals that HKDC1 expression is elevated in obese women with MASH and correlates with liver pathology. In a mouse model, liver-specific HKDC1 knockout (HKDC1LKO) protected against Western diet-induced obesity, glucose intolerance, and MASH features, including steatosis, inflammation, and fibrosis. Transcriptomic analysis showed that HKDC1 deletion reduced pro-inflammatory and pro-fibrotic gene expression, while gut microbiome analysis indicated a shift toward MASH-protective bacteria. These findings suggest that HKDC1 may exacerbate MASH progression through its role in metabolic and inflammatory pathways, making it a potential therapeutic target.

An umbrella review of meta-analyses on the effects of microbial therapy in metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Current pharmacological treatments for metabolic dysfunction-associated steatotic liver disease (MASLD) are often accompanied by adverse side effects. Consequently, probiotics, prebiotics, and synbiotics, which are bioactive compounds from fermented foods and offer fewer side effects, have garnered significant attention as alternative therapeutic strategies.

OBJECTIVE

This study aims to assess the efficacy of microbial therapies-probiotics, prebiotics, and synbiotics-in managing MASLD and to identify the optimal treatment modality for various clinical indicators through a comprehensive umbrella review of meta-analyses.

METHODS

A thorough literature search was conducted across PubMed, Web of Science, EMBASE, Cochrane Library, and Scopus to identify 23 meta-analyses over 18,999 MASLD patients as of November 2024.

RESULTS

The findings indicate that microbial treatments positively influence levels of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), homeostasis model assessment of insulin resistance (HOMA-IR), insulin, tumour necrosis factor-alpha (TNF-α), C-reactive protein (CRP), and body mass index (BMI) in MASLD patients. Notably, probiotics were most effective in reducing TC, ALT, AST, GGT, insulin, TNF-α, and BMI; prebiotics were most effective in reducing TG; and synbiotics were most effective in reducing LDL-C, HOMA-IR, and CRP.

CONCLUSION

Our study provides robust evidence for microbial treatments of MASLD, enabling targeted interventions for different indicators.

Role of the microbiome in regulation of the immune system

Immune health and metabolic functions are intimately connected via diet and the microbiota. Immune cells are continuously exposed to a wide range of microbes and microbial-derived compounds, with important mucosal and systemic ramifications. Microbial fermentation of dietary components in vivo generates thousands of molecules, some of which are integral components of the molecular circuitry that regulates immune and metabolic functions. These in turn protect against aberrant inflammatory or hyper-reactive processes and promote effector immune responses that quickly eliminate pathogens, such as SARS-CoV-2. Potent tolerance mechanisms should ensure that these immune cells do not over-react to non-pathogenic factors (e.g. food proteins), while maintaining the ability to respond to infectious challenges in a robust, effective and well controlled manner. In this review we examine the factors and mechanisms that shape microbiota composition and interactions with the host immune system, their associations with immune mediated disorders and strategies for intervention.

Intrahepatic cholestasis of pregnancy and gestational diabetes: Protocol for a scoping review of associations, risk factors, and outcomes

BACKGROUND

Intrahepatic cholestasis of pregnancy (IHCP) is a pregnancy-related liver disease associated with adverse pregnancy outcomes, including spontaneous preterm labour, fetal hypoxia, meconium-stained liquor and intrauterine death. In women with IHCP, comorbidities may be associated with a greater risk of stillbirth. Recent studies have suggested that cholestasis of pregnancy may be associated with Gestational Diabetes Mellitus (GDM).

OBJECTIVE

This scoping review aims to comprehensively investigate the nature and strength of the association between Intrahepatic Cholestasis of Pregnancy (IHCP) and Gestational Diabetes Mellitus (GDM). The review also seeks to identify common risk factors contributing to the association and explore potential adverse effects associated with the concurrent presence of IHCP and GDM. The findings will inform clinical practice and guide future research initiatives in understanding and managing these pregnancy-related conditions.

METHODS

The scoping review followed the guidelines of Arksey, and O'Malley established in 2005, as well as modifications made to them by Levac et al. in 2010. The PRISMA Scoping review guidance shall be followed in reporting this study. Eight different databases are proposed to search, including Google Scholar, PubMed, Cochrane, Scopus, Embase, CINAHL, the American Diabetes Association, and the Wiley Online Library. Additionally, focused searches within the American Journal of Obstetrics and Gynecology (AJOG) will be conducted, and citation pearl indexing performed.

Bile acid signaling in skeletal muscle homeostasis: from molecular mechanisms to clinical applications

The intricate relationship between bile acid metabolism and skeletal muscle function has emerged as a crucial area of research in metabolic health. This review synthesizes current evidence highlighting the fundamental role of bile acids as key signaling molecules in muscle homeostasis and their therapeutic potential in muscle-related disorders. Recent advances in molecular biology and metabolomics have revealed that bile acids, beyond their classical role in lipid absorption, function as essential regulators of muscle mass and function through multiple signaling pathways, particularly via the nuclear receptor FXR and membrane receptor TGR5. Clinical studies have demonstrated significant associations between altered bile acid profiles and muscle wasting conditions, while experimental evidence has elucidated the underlying mechanisms linking bile acid signaling to muscle protein synthesis, energy metabolism, and regeneration capacity. We critically examine the emerging therapeutic strategies targeting bile acid pathways, including receptor-specific agonists, microbiome modulators, and personalized interventions based on individual bile acid profiles. Additionally, we discuss novel diagnostic approaches utilizing bile acid-based biomarkers and their potential in early detection and monitoring of muscle disorders. This review also addresses current challenges in standardization and clinical translation while highlighting promising future directions in this rapidly evolving field. Understanding the bile acid-muscle axis may provide new opportunities for developing targeted therapies for age-related muscle loss and metabolic diseases.

Bile acids and their receptors in hepatic immunity

Similarly to conventional steroids, bile acids function as signaling molecules, acting on a family of membrane and nuclear receptors. The best-characterized bile acid-regulated receptors are the farnesoid X receptor, activated by primary bile acids, and the G-protein-coupled bile acid receptor 1 (also known as Takeda G protein-coupled receptor 5), which is activated by secondary bile acids, such as lithocholic acid (LCA) and deoxycholic acid. Both the farnesoid X receptor and G-protein-coupled bile acid receptor 1 are expressed in cells of innate immunity, monocytes/macrophages, and natural killer cells. Their activation in these cells provides counter-regulatory signals that are inhibitory in nature and attenuate inflammation. In recent years, however, it has been increasingly appreciated that bile acids biotransformations by intestinal microbiota result in the formation of chemically different secondary bile acids that potently regulate adaptive immunity. The 3-oxoLCA and isoalloLCA, two LCA derivatives, bind receptors such as the retinoic acid receptor-related orphan receptor gamma t (RORγt) and the vitamin D receptor (VDR) that are expressed only by lymphoid cells, extending the regulatory role of bile acids to T cells, including T-helper 17 cells and type 3 innate lymphoid cells (ILC3). In this novel conceptual framework, bile acids have emerged as one of the main components of the postbiota, the waste array of chemical mediators generated by the intestinal microbiota. Deciphering the interaction of these mediators with the immune system in the intestine and liver is a novel and fascinating area of bile acid renaissance.

Hepatic HKDC1 Deletion Alleviates Western Diet-Induced MASH in Mice

The global prevalence of Metabolic dysfunction-associated steatohepatitis (MASH) has been rising sharply, closely mirroring the increasing rates of obesity and metabolic syndrome. MASH exhibits a strong sexual dimorphism where females are affected with more severe forms after menopause. Hexokinase domain-containing protein 1 (HKDC1) has recently been recognized for its role in liver diseases, where its expression is minimal under normal conditions but significantly increases in response to metabolic stressors like obesity and liver injury. This selective upregulation suggests HKDC1s potential specialization in hepatic glucose and lipid dysregulation, linking it closely to the progression of MASLD and MASH. This study aims to clarify the role of HKDC1 in Western diet-induced MASH in female mice by examining its impact on hepatic glucose and lipid metabolism, offering insights into its potential as a therapeutic target and addressing the need for sex-specific research in liver disease. This study reveals that HKDC1 expression is elevated in obese women with MASH and correlates with liver pathology. In a mouse model, liver-specific HKDC1 knockout (HKDC1LKO) protected against Western diet-induced obesity, glucose intolerance, and MASH features, including steatosis, inflammation, and fibrosis. Transcriptomic analysis showed that HKDC1 deletion reduced pro-inflammatory and pro-fibrotic gene expression, while gut microbiome analysis indicated a shift toward MASH-protective bacteria. These findings suggest that HKDC1 may exacerbate MASH progression through its role in metabolic and inflammatory pathways, making it a potential therapeutic target.

Identifying robust biomarkers for the diagnosis and subtype distinction of inflammatory bowel disease through comprehensive serum metabolomic profiling

Inflammatory Bowel Disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC), requires a combination of procedures and tests in diagnosis and discrimination. This study aimed to delineate specific serum metabolomic biomarkers that diagnose IBD and differentiate IBD subgroups. Serum samples and clinical metadata of the participants, IBD patients and Normal Controls (NC), were collected. Untargeted and targeted metabolomic analyses by high-resolution mass spectrometry and multivariate statistical approaches were applied. Further, Receiver Operating Characteristic (ROC) curves, pathways, and network analyses were conducted. Distinct clustering separated IBD patients from the NC, although the CD and UC subgroups overlapped in the non-targeted profiling. Targeted metabolomics revealed elevated tryptophan and indole-3-acetic acid levels and reduced primary-to-secondary bile acid ratios in both CD and UC patients. The differences in specific tryptophan metabolites between CD and UC were identified. The ROC analysis underscored the discriminatory power of the biomarkers (AUC values: NC vs. CD = 0.9738; NC vs. UC = 0.9887; UC vs. CD = 0.7140). Pathway analysis revealed alterations in glycerolipid metabolism, markedly differentiating UC from CD. Network analysis correlated metabolomic markers with the clinical phenotypes of IBD. Serum metabolomic biomarkers can precisely identify IBD, discriminate IBD subtypes, and further reveal the phenotypes of IBD.

Transcriptome atlases of rat brain regions and their adaptation to diabetes resolution following gastrectomy in the Goto-Kakizaki rat

Brain regions drive multiple physiological functions through specific gene expression patterns that adapt to environmental influences, drug treatments and disease conditions. To generate a detailed atlas of the brain transcriptome in the context of diabetes, we carried out RNA sequencing in hypothalamus, hippocampus, brainstem and striatum of the Goto-Kakizaki (GK) rat model of spontaneous type 2 diabetes, which was applied to identify gene transcription adaptation to improved glycemic control following vertical sleeve gastrectomy (VSG) in the GK. Over 19,000 distinct transcripts were detected in the rat brain, including 2794 which were consistently expressed in the four brain regions. Region-specific gene expression was identified in hypothalamus (n = 477), hippocampus (n = 468), brainstem (n = 1173) and striatum (n = 791), resulting in differential regulation of biological processes between regions. Differentially expressed genes between VSG and sham operated rats were only found in the hypothalamus and were predominantly involved in the regulation of endothelium and extracellular matrix. These results provide a detailed atlas of regional gene expression in the diabetic rat brain and suggest that the long term effects of gastrectomy-promoted diabetes remission involve functional changes in the hypothalamus endothelium.

The alleviation by wheat and oat dietary fiber alone or combined of T2DM symptoms in db/db mice

The effects of wheat and oat dietary fiber (DF) alone or combined on T2DM remain unclear. In this research, db/db diabetic mice were fed with diets containing 10% insoluble wheat dietary fiber (WDF), 10% insoluble oat dietary fiber (ODF), and 10% WODF (mixture of WDF and ODF, WDF : ODF = 1 : 1) for 8 weeks. The results showed that WDF, ODF, and WODF all reduced the body weight and fasting blood glucose (FBG) and improved oral glucose tolerance in db/db mice. WDF and ODF alone further relieved insulin resistance and decreased the levels of glycated hemoglobin A1c (GHbA1c), and glycosylated serum protein (GSP). In addition, WDF and ODF alone decreased the levels of TNF-α, IL-6, and IL-1β in serum. The colon function was improved and similar changes were observed in the gut microbiota structure and abundance in all the DF groups. The change of gut microbiota mainly manifested as reducing F/B ratio at the phylum level, while at the genus level as decreasing Enterococcus, Escherichia-Shigella, Erysipelatoclostridium, and unclassified_f_Lachnospiraceae and increase of norank_f_Muribaculaceae, Bacteroides, and Alistipes. Further testing of colonic bile acids (BAs) revealed that WDF, ODF, and WODF all significantly changed the composition of BAs, mainly reducing the levels of UDCA, HDCA, and 3β-UDCA. WODF further decreased DCA and increased β-MCA, LCA-3S, and 12-KCDCA. Importantly, WODF reduced the values of 12-OH-BAs/non-12-OH-BAs. Moreover, the TGR5 level was up-regulated in both the liver and colon, and the FXR level was up-regulated in the liver while down-regulated in the colon in all the DF groups. Furthermore, for the protein level, IRS-1, p-PI3K/PI3K, and AKT were up-regulated in the liver in all the DF groups, while for the mRNA expression level, GLUT4 was up-regulated, and FOXO1, GSK3β, PEPCK, and PGC-1α were down-regulated. WDF and WODF further up-regulated the mRNA expression levels of GYS and down-regulated that of G6Pase. These results suggested that WDF, ODF, and WODF all can alleviate T2DM through the gutmicrobiota-BAs-TGR5/FXR axis and liver IRS-1/PI3K/AKT pathway in db/db mice. WDF and ODF alone are beneficial for improving glucose metabolism and inflammation indicators, while WODF helps improve BAs' profile more in the colon.

Implication of Gut Mycobiome and Virome in Type-2 Diabetes Mellitus: Uncovering the Hidden Players

Type-2 diabetes mellitus (T2DM) is a global epidemic with significant societal costs. The gut microbiota, including its metabolites, plays a pivotal role in maintaining health, while gut dysbiosis is implicated in several metabolic disorders, including T2DM. Although data exists on the relationship between the gut bacteriome and metabolic disorders, further attention is needed for the mycobiome and virome. Recent advancements have begun to shed light on these connections, offering potential avenues for preventive measures. However, more comprehensive investigations are required to untangle the interrelations between different microbial kingdoms and their role in T2DM development or mitigation. This review presents a simplified overview of the alterations in the gut bacteriome in T2DM and delves into the current understanding of the mycobiome and virome's role in T2DM, along with their interactions with the cohabiting bacteriome. Subsequently, it explores into the age-related dynamics of the gut microbiome and the changes observed in the microbiome composition with the onset of T2DM. Further, we explore the basic workflow utilized in gut microbiome studies. Lastly, we discuss potential therapeutic interventions in gut microbiome research, which could contribute to the amelioration of the condition, serve as preventive measures, or pave the way towards personalized medicine.

Exploring the metabolic patterns and response mechanisms of bile acids during fasting: A study with poultry as an example

Fasting is beneficial to alleviate fatty liver, lose weight and improve reproductive function. However, previous studies have shown that, during fasting, disorders of bile acid metabolism were strongly associated with intestinal inflammation. The physiological and biochemical parameters and gene expression of multiple tissues of chickens at every critical time node were measured by ELISA and qPCR. In addition, association analysis was performed based on liver transcriptome sequencing and cecum metabolome data. At the cellular level, the regulatory effects of cecal metabolites on host bile acid metabolism were verified. During fasting, hepatic FXR-SHP-CYP7A1 and ileum-hepatic FXR-SHP-FGF15/19-FGFR4-CYP7A1 negative feedback pathways were activated to inhibit hepatic bile acid synthesis. The ileum FXR-SHP-ASBT pathways are activated, hindered the ileal bile reflux. At the same time, it promotes the secretion of bile acids and cholesterol in the liver, accelerates the utilization of H2O and CO2, to maintain liver homeostasis during fasting. In addition, enhanced gallbladder contraction and increased hunger were observed in laying hens during fasting. At the cellular level, the correlation between CYP7A1 and L-valine was verified, revealing that cecal metabolites of laying hens was enabled to regulate host bile acid metabolism. This study explored the metabolic patterns of bile acids during fasting and identified the main reasons for the accumulation of bile acids in the cecum, which provides a basis for fasting research and offers a reference for the formulation of fasting protocols.

Rapid quantification of murine bile acids using liquid chromatography-tandem mass spectrometry

Interest in bile acids (BAs) is growing due to their emerging role as signaling molecules and their association with various diseases such as colon cancer and metabolic syndrome. Analyzing BAs requires chromatographic separation of isomers, often with long run times, which hinders BA analysis in large studies. Here, we present a high-throughput method based on liquid chromatography-tandem mass spectrometry to quantify BAs in mouse samples. After acidic protein precipitation in the presence of a comprehensive mixture of stable isotope-labeled internal standards (SIL-ISs), BAs are separated on a biphenyl column by gradient elution at basic pH. Quantification is performed using a six-point calibration curve. Except for the separation of β- and ω-muricholic acid (MCA) species, a rapid separation of 27 BA species was achieved in a run time of 6.5 min. Plasma quality controls (QCs) were used to evaluate intra- and inter-day precision. The CV was less than 10% for most BA species and exceeded 20% only for glycohyodeoxycholic (GHDCA) and taurohyodeoxycholic acid (THDCA) due to the lack of a corresponding SIL-IS. The limit of quantification (LoQ) was tested using diluted QCs and was found to be compromised for some BA species as a result of insufficient isotopic purity of the SIL-IS, leading to significant interference with the respective analyte. Finally, we tested the mouse sample material requirements for plasma, bile, and liver samples and determined BA concentrations in C57/BL6N wild-type mice. In conclusion, the LC-MS/MS method presented here permits a rapid and reproducible quantification of the major murine BAs.

Nuclear farnesoid X receptor protects against bone loss by driving osteoblast differentiation through stabilizing RUNX2

The delicate balance between bone formation by osteoblasts and bone resorption by osteoclasts maintains bone homeostasis. Nuclear receptors (NRs) are now understood to be crucial in bone physiology and pathology. However, the function of the Farnesoid X receptor (FXR), a member of the NR family, in regulating bone homeostasis remains incompletely understood. In this study, in vitro and in vivo models revealed delayed bone development and an osteoporosis phenotype in mice lacking FXR in bone marrow mesenchymal stem cells (BMSCs) and osteoblasts due to impaired osteoblast differentiation. Mechanistically, FXR could stabilize RUNX2 by inhibiting Thoc6-mediated ubiquitination, thereby promoting osteogenic activity in BMSCs. Moreover, activated FXR could directly bind to the Thoc6 promoter, suppressing its expression. The interaction between RUNX2 and Thoc6 was mediated by the Runt domain of RUNX2 and the WD repeat of Thoc6. Additionally, Obeticholic acid (OCA), an orally available FXR agonist, could ameliorate bone loss in an ovariectomy (OVX)-induced osteoporotic mouse model. Taken together, our findings suggest that FXR plays pivotal roles in osteoblast differentiation by regulating RUNX2 stability and that targeting FXR may be a promising therapeutic approach for osteoporosis.

Exploring bile acid transporters as key players in cancer development and treatment: Evidence from preclinical and clinical studies

Bile acid transporters (BATs) are integral membrane proteins belonging to various families, such as solute carriers, organic anion transporters, and ATP-binding cassette families. These transporters play a crucial role in bile acid transportation within the portal and systemic circulations, with expression observed in tissues, including the liver, kidney, and small intestine. Bile acids serve as signaling molecules facilitating the absorption and reabsorption of fats and lipids. Dysregulation of bile acid concentration has been implicated in tumorigenesis, yet the role of BATs in this process remains underexplored. Emerging evidence suggests that BATs may modulate various stages of cancer progression, including initiation, development, proliferation, metastasis, and tumor microenvironment regulation. Targeting BATs using siRNAs, miRNAs, and small compound inhibitors in preclinical models and their polymorphisms are well-studied for transporters like BSEP, MDR1, MRP2, OATP1A2, etc., and have shed light on their involvement in tumorigenesis, particularly in cancers such as those affecting the liver and gastrointestinal tract. While BATs' role in diseases like Alagille syndrome, biliary atresia, and cirrhosis have been extensively studied, their implications in cancer warrant further investigation. This review highlights the expression and function of BATs in cancer development and emphasizes the potential of targeting these transporters as a novel therapeutic strategy for various malignancies.

The Positive Regulatory Effect of DBT on Lipid Metabolism in Postpartum Dairy Cows

BACKGROUND/OBJECTIVES

The transition from a non-lactating to a lactating state is a critical period for lipid metabolism in dairy cows. Danggui Buxue Tang (DBT), stimulating energy metabolism, ameliorates diseases related to lipid metabolism disorders and is expected to be an effective supplement for alleviating excessive lipid mobilisation in periparturient dairy cows. This study aimed to investigate the effects of supplemental DBT on serum biochemical indices, faecal microbial communities, and plasma metabolites in dairy cows.

METHODS

Thirty cows were randomly divided into three groups: H-DBT group, L-DBT group, and control group. DBT administration was started on the day of calving and continued once daily for seven days. Faecal and blood samples were collected on calving day, 7 days after calving, and 14 days after calving. The levels of serum biochemical indices were measured at three time points in the three groups using commercial kits. Cows in the H-DBT group and control group were selected for metabolome and 16S rRNA amplicon sequencing.

RESULTS

Our research shows that, in dairy cows 7 days postpartum, DBT significantly reduced serum 3-hydroxybutyric acid (BHB) concentrations and the number of cows with BHB concentrations ≥ 1 mmol/L. Additionally, DBT increased serum total cholesterol contents at both 7 and 14 days postpartum. Analysis of the microbiota community showed that DBT modulated the composition and structure of the hindgut microbiota. Metabolomic analysis revealed decreased plasma acetylcarnitine, 2-hydroxybutyric acid, and BHB levels 7 days postpartum, whereas the TCA cycle was enhanced. At 14 days postpartum, DBT altered the plasma bile acid profile, especially glycine-conjugated bile acids, including GCDCA, GUDCA, and GDCA. Correlation analyses showed that the relative abundances of Bacillus, Solibacillus, Dorea, and Romboutsia were strongly correlated with the differential metabolites, which is crucial for the beneficial effects of DBT.

CONCLUSIONS

DBT improves energy status and lipid metabolism in postpartum dairy cows by modulating hindgut microbiota and serum lipid metabolites.

Probiotics Supplementation for Improving Glucolipid Parameters in Individuals with Prediabetes: A Systematic Review and Meta-Analysis of Randomized Trials

The absence of suitable intervention significantly increases the likelihood of type 2 diabetes mellitus (T2DM) development in people with prediabetes. Recent statistical findings indicate that the gut microbiome might influences the development of insulin resistance. The objective of our study was to assess the efficacy and safety of probiotic supplementation in individuals diagnosed with prediabetes. A thorough search was carried out on the Cochrane Library, Medline, Scopus, and ClinicalTrials.gov databases until September 12th, 2024, using a mix of pertinent keywords. This review incorporates randomized clinical trials (RCTs) concerning the effect of probiotics for prediabetes. We used random-effect models to examine the mean difference (MD). A total of eight RCTs were incorporated. The results of our meta-analysis indicated that probiotics supplementation was associated with higher reduction in hemoglobin A1c (HbA1c) (MD -0.07% (95% CI -0.11, -0.03), p = 0.0005, I2 = 0%) among individuals with prediabetes when compared to placebo. Other indicators such as total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), and body mass index (BMI) did not differ significantly between probiotics and placebo. No significant difference was observed in the occurrence of adverse events (AEs) between the two groups. This study indicates the efficacy and safety of probiotics supplementation to improve the glycemic parameters in patients with prediabetes.

The Gut Microbiota-Related Antihyperglycemic Effect of Metformin

It is critical to sustain the diversity of the microbiota to maintain host homeostasis and health. Growing evidence indicates that changes in gut microbial biodiversity may be associated with the development of several pathologies, including type 2 diabetes mellitus (T2DM). Metformin is still the first-line drug for treatment of T2DM unless there are contra-indications. The drug primarily inhibits hepatic gluconeogenesis and increases the sensitivity of target cells (hepatocytes, adipocytes and myocytes) to insulin; however, increasing evidence suggests that it may also influence the gut. As T2DM patients exhibit gut dysbiosis, the intestinal microbiome has gained interest as a key target for metabolic diseases. Interestingly, changes in the gut microbiome were also observed in T2DM patients treated with metformin compared to those who were not. Therefore, the aim of this review is to present the current state of knowledge regarding the association of the gut microbiome with the antihyperglycemic effect of metformin. Numerous studies indicate that the reduction in glucose concentration observed in T2DM patients treated with metformin is due in part to changes in the biodiversity of the gut microbiota. These changes contribute to improved intestinal barrier integrity, increased production of short-chain fatty acids (SCFAs), regulation of bile acid metabolism, and enhanced glucose absorption. Therefore, in addition to the well-recognized reduction of gluconeogenesis, metformin also appears to exert its glucose-lowering effect by influencing gut microbiome biodiversity. However, we are only beginning to understand how metformin acts on specific microorganisms in the intestine, and further research is needed to understand its role in regulating glucose metabolism, including the impact of this remarkable drug on specific microorganisms in the gut.

The neurotoxicity of acrylamide in ultra-processed foods: interventions of polysaccharides through the microbiota-gut-brain axis

Ultra-processed foods (UPFs) have become popular in recent years, however, the detrimental effects of their excessive consumption have also become evident. Acrylamide (AA), a processing hazard present in UPFs, can further aggravate the harmful effects of UPFs. AA can cause significant damage to both the intestinal barrier and gut microbiota, thereby affecting the nervous system through the microbiota-gut-brain (MGB) axis. Natural polysaccharides have demonstrated the capacity to significantly alleviate the oxidative stress and inflammatory response associated with AA exposure. In addition, they exhibit neuroprotective properties that may be mediated through the MGB axis. This paper reviews literature on the presence of AA in certain UPFs and its potential to inflict serious harm on the human gut microbiota and brain. Moreover, the possibility of utilizing polysaccharides as a preventative measure against AA-induced neurotoxicity was also proposed. These findings provide new insights into the safety risks associated with the overconsumption of UPFs and highlight the potential of polysaccharides to counteract the neurodegeneration induced by AA.

Bifidobacterium longum subsp. longum relieves loperamide hydrochloride-induced constipation in mice by enhancing bile acid dissociation

Bifidobacterium species are known for their efficacy in alleviating constipation. This study aimed to compare the constipation-relieving effects of different Bifidobacterium species (Bifidobacterium longum subsp. longum, Bifidobacterium bifidum, Bifidobacterium animalis, Bifidobacterium breve, Bifidobacterium longum subsp. infantis, and Bifidobacterium adolescentis) and to explore the underlying mechanisms from both the bacterial and host perspectives. We evaluated six Bifidobacterium species for their physiological properties, including growth rate, oligosaccharide utilization, osmotic pressure resistance, cell adhesion, and bile acid dissociation capability. Mice with severe constipation induced by loperamide hydrochloride were treated with these bacteria at a density of 109 CFU per mL for 17 days. Gastrointestinal indices such as fecal water content, time to first black stool defecation, and small intestine propulsion rate were measured to assess constipation relief. Microbiome and metabolome (bile acid and tryptophan) analyses were conducted to elucidate the differences in constipation relief among the species. Our results demonstrated that Bifidobacterium longum subsp. longum exhibited superior physiological traits, including rapid growth, extensive oligosaccharide utilization, and high bile salt dissociation capacity. Notably, only Bifidobacterium longum subsp. longum significantly ameliorated constipation symptoms in the mouse model. Furthermore, this strain markedly restored bile acid and short-chain fatty acid levels in the intestines of constipated mice and altered the composition of the intestinal microbiota. These findings suggest that the enhanced efficacy of Bifidobacterium longum subsp. longum in relieving constipation is associated with its ability to modulate intestinal physiology and microbiota structure and metabolism.

Association of maternal gut microbial metabolites with gestational diabetes mellitus: evidence from an original case-control study, meta-analysis, and Mendelian randomization

BACKGROUND

The associations of gut microbial metabolites, such as trimethylamine N-oxide (TMAO), its precursors, and phenylacetylglutamine (PAGln), with the risk of gestational diabetes mellitus (GDM) remain unclear.

METHODS

Serum samples of 201 women with GDM and 201 matched controls were collected and then targeted metabolomics was performed to examine the metabolites of interest. Multivariable conditional logistic regression was applied to investigate the relationship between metabolites and GDM. Meta-analysis was performed to combine our results and four similar articles searched from online databases, and Mendelian randomization (MR) analysis was eventually conducted to explore the causalities.

RESULTS

In the case-control study, after dichotomization and comparing the higher versus the lower group, the adjusted odds ratio and 95% confidence interval of choline and L-carnitine with GDM were 2.124 (1.186-3.803) and 0.293 (0.134-0.638), respectively; but neutral relationships between TMAO, betaine, and PAGln with GDM were observed. The following meta-analysis consistently revealed that L-carnitine was negatively associated with GDM. However, MR analyses showed no evidence of causalities.

CONCLUSIONS

Maternal levels of L-carnitine were related to the risk of GDM in both the original case-control study and meta-analysis. However, we did not observe any genetic evidence to establish a causal relationship between this metabolite and GDM.

Bile acids as a key target: traditional Chinese medicine for precision management of insulin resistance in type 2 diabetes mellitus through the gut microbiota-bile acids axis

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease caused by insulin resistance (IR) and insufficient insulin secretion. Its characteristic pathophysiological processes involve the interaction of multiple mechanisms. In recent years, globally, the prevalence of T2DM has shown a sharp rise due to profound changes in socio-economic structure, the persistent influence of environmental factors, and the complex role of genetic background. It is worth noting that most T2DM patients show significant IR, which further exacerbates the difficulty of disease progression and prevention. In the process of extensively exploring the pathogenesis of T2DM, the dynamic equilibrium of gut microbes and its diverse metabolic activities have increasingly emphasized its central role in the pathophysiological process of T2DM. Bile acids (BAs) metabolism, as a crucial link between gut microbes and the development of T2DM, not only precisely regulates lipid absorption and metabolism but also profoundly influences glucose homeostasis and energy balance through intricate signaling pathways, thus playing a pivotal role in IR progression in T2DM. This review aims to delve into the specific mechanism through which BAs contribute to the development of IR in T2DM, especially emphasizing how gut microbes mediate the metabolic transformation of BAs based on current traditional Chinese medicine research. Ultimately, it seeks to offer new insights into the prevention and treatment of T2DM. Diet, genetics, and the environment intricately sculpt the gut microbiota and BAs metabolism, influencing T2DM-IR. The research has illuminated the significant impact of single herbal medicine, TCM formulae, and external therapeutic methods such as electroacupuncture on the BAs pool through perturbations in gut microbiota structure. This interaction affects glucose and lipid metabolism as well as insulin sensitivity. Additionally, multiple pathways including BA-FXR-SHP, BA-FXR-FGFR15/19, BA-FXR-NLRP3, BA-TGR5-GLP-1, BAs-TGR5/FXR signaling pathways have been identified through which the BAs pool significantly alter blood glucose levels and improve IR. These findings offer novel approaches for enhancing IR and managing metabolic disorders among patients with T2DM.

Jianwei Shoutai Pills alleviates miscarriage by modulating gut microbial production of BAs and NLRP3-inflammasome at the maternal-fetal interface of rats

BACKGROUND

Miscarriage has the characteristics of recurrent attacks and complex etiology, so it is gradually attracted the wide attention of scholars in the fields of reproduction. Potential association between gut microbiome (GM) and pregnancy disorders has been investigated. Jianwei Shoutai pills (JWP), as a representative formula, have been proven to have protective effect in both clinical and experimental research in miscarriage. However, the specific mechanism of JWP in miscarriage through GM remains unclear.

PURPOSE

To investigate the underlying mechanism of JWP against miscarriage through the gut-uterus axis.

METHODS

The effects of JWP on an RU486-induced rat model of miscarriage were evaluated by embryo resorption rate, vaginal bleeding rate, and appearance of the uterus and embryo. We used 16S rRNA sequencing to measure the extent of the effect of JWP on GM of rats with miscarriage. Bile acid (BA) content of the feces of rats treated with JWP was evaluated by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS). The activation of bile acid-associated receptor, Farnesoid X receptor (FXR), was evaluated by immunofluorescence. The expression level of NLRP3 inflammasome-associated protein was detected by Western blot or Elisa. Fecal microbiota transplantation (FMT) was used to confirm that GM was essential for the therapeutic effect of JWP in miscarriage.

RESULTS

JWP significantly ameliorated miscarriage symptoms and embryo resorption rate caused by RU486-induced miscarriage as well as restored the abnormal activation of NLRP3-inflammasome at the maternal-fetal interface. Furthermore, JWP can significantly regulated GM dysbiosis and closely associated with BA metabolism by KEGG pathway prediction analysis. Several BA content were significantly restored by HPLC-MS. The expression of NLRP3 inflammasome-associated protein at maternal-fetal interface was reversed by JWP. Combined with FMT, JWP could regulate activation of NLRP3 at the maternal-fetal interface by BAs produced by GM.

CONCLUSION

JWP restored abnormal activation of the NLRP3-inflammasome in an RU486-induced miscarriage rat model, and corrected the BA disorder by regulating imbalance of the GM.

PbsNRs: predict the potential binders and scaffolds for nuclear receptors

Nuclear receptors (NRs) are a class of essential proteins that regulate the expression of specific genes and are associated with multiple diseases. In silico methods for prescreening potential NR binders with predictive binding ability are highly desired for NR-related drug development but are rarely reported. Here, we present the PbsNRs (Predicting binders and scaffolds for Nuclear Receptors), a user-friendly web server designed to predict the potential NR binders and scaffolds through proteochemometric modeling. The utility of PbsNRs was systemically evaluated using both chemical compounds and natural products. Results indicated that PbsNRs achieved a good prediction performance for chemical compounds on internal (ROC-AUC = 0.906, where ROC is Receiver-Operating Characteristic curve and AUC is the Area Under the Curve) and external (ROC-AUC = 0.783) datasets, outperforming both compound-ligand interaction tools and NR-specific predictors. PbsNRs also successfully identified bioactive chemical scaffolds for NRs by screening massive natural products. Moreover, the predicted bioactive and inactive natural products for NR2B1 were experimentally validated using biosensors. PbsNRs not only aids in screening potential therapeutic NR binders but also helps discover the essential molecular scaffold and guide the drug discovery for multiple NR-related diseases. The PbsNRs web server is available at http://pbsnrs.badd-cao.net.

Biological functions and pharmacological behaviors of bile acids in metabolic diseases

BACKGROUND

Bile acids, synthesized endogenously from cholesterol, play a central role in metabolic regulation within the enterohepatic circulatory system. Traditionally known as emulsifying agents that facilitate the intestinal absorption of vitamins and lipids, recent research reveals their function as multifaceted signal modulators involved in various physiological processes. These molecules are now recognized as key regulators of chronic metabolic diseases and immune dysfunction. Despite progress in understanding their roles, their structural diversity and the specific functions of individual bile acids remain underexplored.

AIM OF REVIEW

This study categorizes the bile acids based on their chemical structures and their roles as signaling molecules in physiological processes. It consolidates current knowledge and provides a comprehensive overview of the current research. The review also includes natural and semisynthetic variants that have demonstrated potential in regulating metabolic processes in animal models or clinical contexts.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Bile acids circulate primarily within the enterohepatic circulation, where they help maintain a healthy digestive system. Disruptions in their balance are linked to metabolic disorders, hepatobiliary diseases and intestinal inflammation. Through receptor-mediated pathways, bile acids influence the progression of metabolic diseases by regulating glucose and lipid metabolism, immune function, and energy expenditure. This review aims to provide a comprehensive, systematic foundation to for understanding their physiological roles and supporting future therapeutic developments for metabolic and inflammatory diseases.

A Mix of Probiotic Strains Prevents Hepatic Steatosis, and Improves Oxidative Stress Status and Gut Microbiota Composition in Obese Mice

SCOPE

The gut microbiota plays a role in fat accumulation and energy homeostasis. Therefore, probiotic supplementation may improve metabolic parameters and control body weight.

METHODS AND RESULTS

In this study, mice are fed either a high-fat diet (HFD) or an HFD supplemented with oral gavage of a mixture of three probiotic strains, Bifidobacterium lactis Lafti B94, Lactobacillus plantarum HA-119, and Lactobacillus helveticus Lafti L10 for 7 weeks. It finds that probiotic supplementation modulates body weight gain, food energy efficiency, and fat accumulation caused by the HFD. This probiotic mix prevents liver damage and lipid metabolic disorders in HFD-fed obese mice. The probiotic supplementation significantly downregulates the expression of the proinflammatory cytokines interleukin-1β, tumor necrosis factor-α, and malondialdehyde (MDA) in the liver and upregulated catalase (CAT), superoxide dismutase (SOD), and nuclear respiratory factor 1 (Nrf1) expression. Mice supplemented with the probiotic mix also show different microbiota compositions, with an increase in Clostridia_UCG-014 and Lachnospiraceae_nk4a136_group and a decrease in the Dubosiella genus compared with those in mice fed only an HFD. Finally, the amounts of fecal pentanoic acid and the three bile acid species increase in mice with probiotic supplementation.

CONCLUSION

Treatment with a combination of a mixture of three probiotic strains, B. lactis Lafti B94, L. plantarum HA-119, and L. helveticus Lafti L10 for 7 weeks, ameliorates the effects of HFD induced obesity in mice.

Altered bile acids profile is a risk factor for hyperandrogenism in lean women with PCOS: a case control study

The levels of fasting-state serum bile acids (BAs) in individuals with polycystic ovary syndrome (PCOS) differ from those of control subjects. However, there is a lack of research on the BAs profile in lean women with PCOS and whether these changes are linked to the host metabolism. Therefore, our objective was to investigate the synthesis and metabolism of serum BAs in lean women with PCOS and assess the correlation between BAs and clinical characteristics. This study employed a cross-sectional design of lean women with PCOS (n = 240) in comparison to a control group (n = 80) consisting of healthy lean women. The findings revealed significant increases in the levels of non-12-OH BAs and chenodeoxycholic acid (CDCA)% (both P < 0.05) in lean women with PCOS. Additionally, a positive correlation was observed between CDCA% and total testosterone (T) (r = 0.130, P = 0.044) and free androgen index (FAI) (r = 0.153, P = 0.019). Furthermore, a decreased ratio of cholic acid/chenodeoxycholic acid (CA/CDCA) (P < 0.001) was observed in lean women with PCOS, suggesting the depletion or downregulation of CYP8B1. Receiver operating characteristic curve analysis indicated that the combination of CDCA/CA and DHEAS could potentially be used as a characteristic factor for PCOS in lean women. It is possible that enzymatic modifications in the liver could play a role in regulating hyperandrogenism in this specific subgroup of lean women with PCOS.

Yeast β-glucan supplementation lowers insulin resistance without altering microbiota composition compared with placebo in subjects with type II diabetes: a phase I exploratory study

The increased global prevalence of type II diabetes mellitus (T2DM) is associated with consumption of low fibre 'Western diets'. Characteristic metabolic parameters of these individuals include insulin resistance, high fasting and postprandial glucose, as well as low-grade systemic inflammation. Gut microbiota composition is altered significantly in these cohorts suggesting a causative link between diet, microbiota and disease. Dietary fibre consumption has been shown to alleviate these changes and improve glucose parameters in individuals with metabolic disease. We previously reported that yeast β-glucan (yeast beta-1,3/1,6-D-glucan; Wellmune) supplementation ameliorated hyperinsulinaemia and insulin resistance in a murine model. Here, we conducted a randomised, placebo-controlled, two-armed dietary fibre phase I exploratory intervention study in patients with T2DM. The primary outcome measure was alteration to microbiota composition, while the secondary outcome measures included markers of glycaemic control, inflammation as well as metabolomics. Patients were supplemented with 2·5g/day of maltodextrin (placebo) or yeast β-1,3/1,6-D-glucan (treatment). Yeast β-glucan (Wellmune) lowered insulin resistance compared with the placebo maltodextrin after 8 weeks of consumption. TNFα was significantly lower after 4 weeks of β-glucan supplementation. Significantly higher fecal concentrations of several bile acids were detected in the treatment group when compared with the placebo after 8 weeks. These included tauroursodeoxycholic acid, which was previously shown to improve glucose control and lower insulin resistance. Interestingly, the hypoglycaemic and anti-inflammatory effect of yeast β-glucan was independent of any changes in fecal microbiota composition or short-chain fatty acid levels. Our findings highlight the potential of yeast β-glucan to lower insulin resistance in patients with T2DM.

Reinventing gut health: leveraging dietary bioactive compounds for the prevention and treatment of diseases

The human gut harbors a complex and diverse microbiota essential for maintaining health. Diet is the most significant modifiable factor influencing gut microbiota composition and function, particularly through bioactive compounds like polyphenols, dietary fibers, and carotenoids found in vegetables, fruits, seafood, coffee, and green tea. These compounds regulate the gut microbiota by promoting beneficial bacteria and suppressing harmful ones, leading to the production of key microbiota-derived metabolites such as short-chain fatty acids, bile acid derivatives, and tryptophan metabolites. These metabolites are crucial for gut homeostasis, influencing gut barrier function, immune responses, energy metabolism, anti-inflammatory processes, lipid digestion, and modulation of gut inflammation. This review outlines the regulatory impact of typical bioactive compounds on the gut microbiota and explores the connection between specific microbiota-derived metabolites and overall health. We discuss how dietary interventions can affect disease development and progression through mechanisms involving these metabolites. We examine the roles of bioactive compounds and their metabolites in the prevention and treatment of diseases including inflammatory bowel disease, colorectal cancer, cardiovascular diseases, obesity, and type 2 diabetes mellitus. This study provides new insights into disease prevention and underscores the potential of dietary modulation of the gut microbiota as a strategy for improving health.

Metabolomic profiling reveals the step-wise alteration of bile acid metabolism in patients with diabetic kidney disease

BACKGROUND

Diabetic kidney disease (DKD) is the major complication of diabetes concomitant with gut dysbiosis and glycometabolic disorder, which are strongly associated with bile acid (BA) metabolism. Yet studies investigating the BA metabolism involving in DKD pathogenesis are limited. This study aimed to explore the metabolomic profiling of BAs in DKD and analyze its association with DKD progression.

METHODS

An ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was established to quantify BAs in the plasma, fecal and urine samples of patients with DKD or T2DM and healthy individuals (n = 30 for each group). The key BAs associated with DKD were identified by orthogonal partial least-squares discriminant analysis (OPLS-DA) and receiver-operating characteristic (ROC) curve. Polynomial regression and Pearson's correlation analyses were performed to assess the correlation between the key BAs and the clinical indicators reflecting DKD progression.

RESULTS

Metabolomic profiling of 50 kinds of BAs presented the markedly step-wise alterations of BAs in plasma and feces as well as the little in urine of patients with DKD. Eight kinds of BAs in the plasma, eight kinds in the feces and three kinds in the urine were abnormally expressed, accompanying with the increased conjugated/unconjugated ratios of cholic acid, deoxycholic acid, chenodeoxycholic acid, ursodeoxycholic acid and hyocholic acid in the plasma, and of cholic acid, chenodeoxycholic acid and lithocholic acid in the feces. Moreover, the increased plasma level of glycochenodeoxycholic acid, and the increased fecal levels of glycolithocholic acid, 7-ketodeoxycholic acid and chenodeoxycholic acid-3-β-D-glucuronide are strongly correlated with the clinical indicators reflecting DKD progression, including eGFR, 24 h urinary protein and 24 h urinary microalbumin.

CONCLUSIONS

Our study for the first time disclosed the specific alterations of BA metabolism reflecting the step-wise progression of DKD, providing the basis for early identification and therapeutical strategies for DKD.

Resistant Potato Starch Supplementation Reduces Serum Free Fatty Acid Levels and Influences Bile Acid Metabolism

Background: Resistant starches, such as high-amylose maize starch and resistant potato starch (RPS), have prebiotic effects that are linked to improved metabolism at >15 g/day, but the effects at lower doses have not been reported. Methods: We performed an exploratory post hoc analysis of free fatty acids (FFAs), bile acids (BAs), and ketone bodies in serum previously collected from a randomized, double-blind, placebo-controlled clinical trial evaluating the effects of one- and four-week consumption of 3.5 g/day RPS versus a placebo using two-way ANOVA adjusted by pFDR. Associations between week 4 changes in FFAs, BAs, and ketone bodies were assessed by Pearson's correlations. Results: RPS consumption reduced total FFAs relative to the placebo, including multiple unsaturated FFAs and octanedioic acid, with reductions in taurine- and glycine-conjugated secondary BAs also detected (q < 0.05). No changes in ketone bodies were observed (q > 0.05). Changes in 7-ketodeoxycholic acid (r = -0.595) and glycolithocholic acid (r = -0.471) were inversely correlated with treatment-induced reductions in FFAs for RPS but not the placebo, suggesting the effects were from the prebiotic. Shifts in β-hydroxybutyrate were further correlated with FFA changes in both treatments (q < 0.05). Conclusions: These findings demonstrate that low doses of RPS positively influence fatty acid metabolism in humans, reducing circulating levels of FFA and conjugated BAs.

Analysis of the liver-gut axis including metabolomics and intestinal flora to determine the protective effects of kiwifruit seed oil on CCl4-induced acute liver injury

The hepatoprotective effects of kiwifruit seed oil (KSO) were evaluated on acute liver injury (ALI) induced by carbon tetrachloride (CCl4) in vivo. Network pharmacology was used to predict active compounds and targets. Metabolomics and gut microbiota analyses were used to discover the activity mechanism of KSO. KSO improved the liver histological structure, significantly reduced serum proinflammatory cytokine levels, and increased liver antioxidant capacity. The metabolomics analysis showed that KSO may have hepatoprotective effects by controlling metabolites through its participation in signaling pathways like tryptophan metabolism, glycolysis/gluconeogenesis, galactose metabolism, and bile secretion. The gut microbiota analysis demonstrated that KSO improved the composition and quantity of the gut flora. Network pharmacological investigations demonstrated that KSO operated by altering Ptgs2, Nos2, Ppara, Pparg and Serpine1 mRNA levels. All evidence shows that KSO has a hepatoprotective effect, and the mechanism is connected to the regulation of metabolic disorders and intestinal flora.

Comparative analysis of bile acid composition and metabolism in the liver of Bufo gargarizans aquatic larvae and terrestrial adults

Bile acids are crucial for lipid metabolism and their composition and metabolism differ among species. However, there have been no data on the differences in the composition and metabolism of bile acids between aquatic larvae and terrestrial adults of amphibians. This study explored the differences in composition and metabolism of bile acid between Bufo gargarizans larvae and adults. The results demonstrated that adult liver had a lower total bile acid level and a higher conjugated/total bile acid ratio than larval liver. Meanwhile, histological analysis revealed that the larvae showed a larger cross-sectional area of bile canaliculi lumen compared with the adults. The transcriptomic analysis showed that B. gargarizans larvae synthesized bile acids through both the alternative and the 24-hydroxylase pathway, while adults only synthesized bile acids through the 24-hydroxylase pathway. Moreover, bile acid regulator-related genes FXR and RXRα were highly expressed in adult, whereas genes involved in bile acid synthesis (CYP27A1 and CYP46A1) were highly expressed in larvae. The present study will provide valuable insights into understanding metabolic disorders and exploring novel bile acid-based therapeutics.

Identification of dietary factors that impact the gut microbiota associated with vitiligo: A Mendelian randomization study and meta-analysis

Previous observational studies have suggested that gut microbiota might be associated with vitiligo. However, owing to the limitations in observational studies of reverse causality and confounders, it remains unclear that whether and how the causal relationships exist. The results suggested that pylum.Bacteroidetes, family.BacteroidalesS24.7, genus.LachnospiraceaeND3007, genus.Marvinbryantia are protective factors for vitiligo. Conversely, family.Lachnospiraceae, order.Burkholderiales, genus.Adlercreutzia, genus.Catenibacterium and genus.Lachnospira are risk factors for vitiligo. In addition, the causative connection between dietary factors and the gut microbiota associated with vitiligo was also investigated. The results revealed that 'alcohol intake versus 10 years pervious' results in a reduction in the abundance of genus.Lachnospiraceae ND3007 and family.BacteroidalesS24.7, bread intake leads to a reduction of genus.Marvinbryantia, 'average weekly red wine intake' is linked to a decrease in the abundance of order.Burkholderiales, tea intake is associated with an augmentation in the abundance of genus.Catenibacterium, salad/raw vegetable intake elevates the abundance of order.Burkholderiales. In summary, this Mendelian randomization study substantiates potential causal effects of gut microbiota on vitiligo. Modulating the gut microbiota through regulating dietary composition may be a novel strategy for preventing vitiligo.

Bile acid profiles and mRNA abundance of bile acid-related genes in adipose tissue of dairy cows with high versus normal body condition

Besides their lipid-digestive role, bile acids (BA) influence overall energy homeostasis, such as glucose and lipid metabolism. We hypothesized that BA along with their receptors, regulatory enzymes, and transporters are present in subcutaneous adipose tissue (scAT). In addition, we hypothesized that their mRNA abundance varies with the body condition of dairy cows around calving. Therefore, we analyzed BA in serum and scAT as well as the mRNA abundance of BA-related enzymes, transporters, and receptors in scAT during the transition period in cows with different body conditions around calving. In a previously established animal model, 38 German Holstein cows were divided into either a high (HBCS; n = 19) or normal BCS (NBCS; n = 19) group based on their BCS and back-fat thickness (BFT). Cows were fed different diets to achieve the targeted differences in BCS and BFT (NBCS: BCS <3.5, BFT <1.2 cm; HBCS: BCS >3.75, BFT >1.4 cm) until dry-off at 7 wk antepartum. During the dry period and subsequent lactation, both groups were fed the same diets according to their energy demands. Using a targeted metabolomics approach via liquid chromatography-electrospray ionization-MS /MS, BA were analyzed in serum and scAT at wk -7, 1, 3, and 12 relative to parturition. In serum, 15 BA were observed: cholic acid (CA), chenodeoxycholic acid (CDCA), glycocholic acid (GCA), taurocholic acid (TCA), glycochenodeoxycholic acid (GCDCA), taurochenodeoxycholic acid, deoxycholic acid (DCA), lithocholic acid, glycodeoxycholic acid (GDCA), glycolithocholic acid, taurodeoxycholic acid, taurolithocholic acid, β-muricholic acid, tauromuricholic acid (sum of α and β), and glycoursodeoxycholic acid, whereas in scAT 7 BA were detected: CA, GCA, TCA, GCDCA, taurochenodeoxycholic acid, GDCA, and taurodeoxycholic acid. In serum and scAT samples, the primary BA CA and its conjugate GCA were predominantly detected. Increasing serum concentrations of CA, CDCA, TCA, GCA, GCDCA, DCA, and β-muricholic acid with the onset of lactation might be related to the increasing DMI after parturition. Furthermore, serum concentrations of CA, CDCA, GCA, DCA, GCDCA, TCA, lithocholic acid, and GDCA were lower in HBCS cows compared with NBCS cows, concomitant with increased lipolysis in HBCS cows. The correlation between CA in serum and scAT may point to the transport of CA across cell membranes. Overall, the findings of the present study suggest a potential role of BA in lipid metabolism depending on the body condition of periparturient dairy cows.

Gpbar-1/cAMP/PKA signaling mitigates macrophage-mediated acute cholestatic liver injury via antagonizing NLRP3-ASC inflammasome

Acute cholestatic liver injury (ACLI) is a disease associated with bile duct obstruction that causes liver inflammation and apoptosis. Although G protein-coupled bile acid receptor1 (Gpbar-1) has diverse metabolic roles, its involvement in ACLI-associated immune activation remains unclear. Liver tissues and blood samples from 20 patients with ACLI and 20 healthy individuals were analyzed using biochemical tests, H&E staining, western blotting, and immunohistochemistry to verify liver damage and expression of Gpbar-1. The expression of Gpbar-1, cAMP/PKA signaling, and the NLRP3 inflammasome was tested in wild-type (WT) and Gpbar-1 knockdown (si-Gpbar-1) mice with ACLI induced by bile duct ligation (BDL) and in primary Kupffer cells (KCs) with or without Gpbar-1-siRNA. The results showed that total bile acids and Gpbar-1 expressions were elevated in patients with ACLI. Gpbar-1 knockdown significantly worsened BDL-induced acute hepatic damage, inflammation, and liver apoptosis in vivo. Knockdown of Gpbar-1 heightened KC sensitivity to lipopolysaccharide (LPS) stimulation. Gpbar-1 activation inhibited LPS-induced pro-inflammatory responses in normal KCs but not in Gpbar-1-knockdown KCs. Notably, NLRP3-ASC inflammasome expression was effectively enhanced by Gpbar-1 deficiency. Additionally, Gpbar-1 directly increased intracellular cAMP levels and PKA phosphorylation, thus disrupting the NLRP3-ASC inflammasome. The pro-inflammatory characteristic of Gpbar-1 deficiency was almost neutralized by the NLRP3 inhibitor CY-09. In vitro, M1 polarization was accelerated in LPS-stimulated Gpbar-1-knockdown KCs. Therapeutically, Gpbar-1 deficiency exacerbated BDL-induced ACLI, which could be rescued by inhibition of the NLRP3-ASC inflammasome. Our study reveal that Gpbar-1 may act as a novel immune-mediated regulator of ACLI by inhibiting the NLRP3-ASC inflammasome.

Sarmentol H derived from Sedum sarmentosum Bunge directly targets FXR to mitigate cholestasis by recruiting SRC-1

BACKGROUND

Farnesoid X receptor (FXR) is a vital receptor for bile acids and plays an important role in the treatment of cholestatic liver disease. In addition to traditional bile acid-based steroidal agonists, synthetic alkaloids are the most commonly reported non-steroidal FXR agonists. Sarmentol H is a nor-sesquiterpenoid obtained from Sedum sarmentosum Bunge, and in vitro screening experiments have shown that it might be related to the regulation of the FXR pathway in a previous study.

PURPOSE

To investigate the therapeutic effects of sarmentol H on cholestasis and to determine whether sarmentol H directly targets FXR to mitigate cholestasis. Furthermore, this study aimed to explore the key amino acid residues involved in the binding of sarmentol H to FXR through site-directed mutagenesis.

METHODS

An intrahepatic cholestasis mouse model was established to investigate the therapeutic effects of sarmentol H on cholestasis. In vitro experiments, including Co-Ip and FXR-EcRE-Luc assays, were performed to assess whether sarmentol H activates FXR by recruiting the receptor coactivator SRC1. CETSA, SIP, DARTS, and ITC were used to determine the binding of sarmentol H to FXR protein. The key amino acid residues for sarmentol H binding to FXR were analyzed by molecular docking and site-directed mutagenesis. Finally, we conducted in vivo experiments on wild-type and Fxr-/- mice to further validate the anticholestatic target of sarmentol H.

RESULTS

Sarmentol H had significant ameliorative effects on the pathological conditions of cholestatic mice induced with ANIT. In vitro experiments suggested that it is capable of activating FXR and regulating downstream signaling pathways by recruiting SRC1. The target validation experiments showed that sarmentol H had the ability to bind to FXR as a ligand (KD = 2.55 μmol/L) and enhance the stability of its spatial structure. Moreover, site-directed mutagenesis revealed that THR292 and TYR365 were key binding sites for sarmentol H and FXR. Furthermore, knockout of the Fxr gene resulted in a significantly higher degree of ANIT-induced cholestatic liver injury than that in wild-type cholestatic mice, and the amelioration of cholestasis or regulatory effects on FXR downstream genes by sarmentol H also disappeared in Fxr-/- cholestatic mice.

CONCLUSION

Sarmentol H is an FXR agonist. This is the first study to show that it exerts a significant therapeutic effect on cholestatic mice, and can directly bind to FXR and activate it by recruiting the coactivator SRC1.

Impact of imidacloprid exposure on gestational hyperglycemia: A multi-omics analysis

Imidacloprid (IMI), a commonly utilized neonicotinoid insecticide, has been identified to adversely impact glucose homeostasis. Pregnant women are believed to be more sensitive to toxins than non-pregnant women, and the impact of IMI exposure on gestational hyperglycemia remain unclear. To explore the impact, pregnant mice fed a high-fat diet were exposed to different doses (0.06, 0.6, 6 mg/kg bw/day) of IMI by gavage. Glucose homeostasis-related parameters were measured. The glucose homeostasis influenced by IMI treatment was explored through integrating gut microbiota, metabolomic and transcriptomic analysis. Results showed that IMI-H (6 mg/kg bw/day) exposure notably restricted gestational weight gain and perturbed glucose homeostasis characterized by reduced glucose tolerance and insulin sensitivity, alongside elevated levels of fasting blood glucose and insulin. Multi-omics analysis revealed that IMI-H exposure induced significant changes in the richness and composition of the gut microbiome. The metabolite profiles of serum samples and cecal contents, and transcriptome of liver and ileum were all affected by IMI-H treatment. The altered gut microbiota, metabolites and genes exhibited significant correlations with glucose homeostasis-related parameters. These differential metabolites and genes were implicated in various metabolic pathways including bile secretion, glucagon signaling pathway, lipid metabolism, fatty acid metabolism. Significant correlations were observed between the altered gut microbiota and caecum metabolome as well as liver transcriptome. For example, the abundance of Oscillibacter was strongly correlated with gut microflora-related metabolites (Icosenoic acid, Lysosulfatide, and fluticasone) and liver differential genes (Grin3b, Lifr, and Spta1). Together, IMI exposure resulted in significant changes in microbial composition, along with alterations in certain metabolites and genes associated with metabolic process, which may promote gestational hyperglycemia.

The Role of Nondigestible Oligosaccharides in Alleviating Human Chronic Diseases by Regulating the Gut Microbiota: A Review

The gut has been a focus of chronic disease research. The gut microbiota produces metabolites that act as signaling molecules and substrates, closely influencing host health. Nondigestible oligosaccharides (NDOs), as a common dietary fiber, play an important role in regulating the structure and function of the gut microbiota. Their mechanism of action is mainly attributed to providing a carbon source as specific probiotics, producing related metabolites, and regulating the gut microbial community. However, due to the selective utilization of oligosaccharides, some factors, such as the type and structure of oligosaccharides, have different impacts on the composition of microbial populations and the production of metabolites in the colon ecosystem. This review systematically describes the key factors influencing the selective utilization of oligosaccharides by microorganisms and elaborates how oligosaccharides affect the host's immune system, inflammation levels, and energy metabolism by regulating microbial diversity and metabolic function, which in turn affects the onset and progress of chronic diseases, especially diabetes, obesity, depression, intestinal inflammatory diseases, and constipation. In this review, we re-examine the interaction mechanisms between the gut microbiota and its associated metabolites and diseases, and we explore new strategies for promoting human health and combating chronic diseases through dietary interventions.