Bile Acids as Hormones: The FXR-FGF15/19 Pathway

Sodium sulphate ameliorates hypercholesterolemia via the upregulation of Cyp7a1 in hepatocytes and alleviates hepatic insulin resistance via the downregulation of Trib3 in mice with high cholesterol diets

Amelioration of hypercholesterolemia is essential for the treatment of atherosclerotic cardiovascular disease. Sodium sulphate is the effective component of mirabilite, which has been used in traditional Chinese medicine for the treatment of various diseases. In the present study, C57BL/6 mice were fed with a high-cholesterol diet (HCD) for 7 weeks and were treated with sodium sulphate in the last three of those weeks. Sodium sulphate significantly reduced the total cholesterol level and the low-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio in the serum of mice fed the HCD. In addition, cytochrome P450 7a1 and 39a1 were significantly upregulated in the livers of mice treated with sodium sulphate. Furthermore, tribbles pseudokinase 3 expression was significantly increased in the livers of mice fed the HCD, but was significantly reduced by sodium sulphate treatment. In terms of the insulin signaling pathway, the ratio of phosphorylated AKT to total AKT in the livers of mice fed the HCD was significantly lower compared with that of control mice fed a normal diet, but was significantly increased by sodium sulphate treatment. Sodium sulphate treatment also reduced the levels of fibroblast growth factor (FGF)15 in the ileum and inhibited the FGF15/FGF receptor 4-Klotho β/c-Jun N-terminal kinase/c-Jun signaling pathway in the livers of mice fed the HCD. In addition, sodium sulphate changed the composition of the gut microbiota of mice fed the HCD. In conclusion, sodium sulphate may mitigate hypercholesterolemia and hepatic insulin resistance in mice fed an HCD.

Fibroblast growth factor receptor 4 deficiency in macrophages aggravates experimental colitis by promoting M1-polarization

OBJECTIVE AND DESIGN

Compelling evidence indicates that dysregulated macrophages may play a key role in driving inflammation in inflammatory bowel disease (IBD). Fibroblast growth factor (FGF)-19, which is secreted by ileal enterocytes in response to bile acids, has been found to be significantly lower in IBD patients compared to healthy individuals, and is negatively correlated with the severity of diarrhea. This study aims to explore the potential impact of FGF19 signaling on macrophage polarization and its involvement in the pathogenesis of IBD.

METHODS

The dextran sulfate sodium (DSS)-induced mouse colitis model was utilized to replicate the pathology of human IBD. Mice were created with a conditional knockout of FGFR4 (a specific receptor of FGF19) in myeloid cells, as well as mice that overexpressing FGF19 specifically in the liver. The severity of colitis was measured using the disease activity index (DAI) and histopathological staining. Various techniques such as Western Blotting, quantitative PCR, flow cytometry, and ELISA were employed to assess polarization and the expression of inflammatory genes.

RESULTS

Myeloid-specific FGFR4 deficiency exacerbated colitis in the DSS mouse model. Deletion or inhibition of FGFR4 in bone marrow-derived macrophages (BMDMs) skewed macrophages towards M1 polarization. Analysis of transcriptome sequencing data revealed that FGFR4 deletion in macrophages significantly increased the activity of the complement pathway, leading to an enhanced inflammatory response triggered by LPS. Mechanistically, FGFR4-knockout in macrophages promoted complement activation and inflammatory response by upregulating the nuclear factor-κB (NF-κB)-pentraxin3 (PTX3) pathway. Additionally, FGF19 suppressed these pathways and reduced inflammatory response by activating FGFR4 in inflammatory macrophages. Liver-specific overexpression of FGF19 also mitigated inflammatory responses induced by DSS in vivo.

CONCLUSION

Our study highlights the significance of FGF19-FGFR4 signaling in macrophage polarization and the pathogenesis of IBD, offering a potential new therapeutic target for IBD.

Dan-shen Yin promotes bile acid metabolism and excretion to prevent atherosclerosis via activating FXR/BSEP signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Dan-shen Yin (DSY), a traditional prescription, has been demonstrated to be effective in decreasing hyperlipidemia and preventing atherosclerosis (AS), but its mechanism remains unknown. We hypothesized that DSY activates farnesoid X receptor (FXR) to promote bile acid metabolism and excretion, thereby alleviating AS.

AIM OF THE STUDY

This study was designed to explore whether DSY reduces liver lipid accumulation and prevents AS by activating FXR and increasing cholesterol metabolism and bile acid excretion.

MATERIALS AND METHODS

The comprehensive chemical characterization of DSY was analyzed by UHPLC-MS/MS. The AS models of ApoE-/- mice and SD rats was established by high-fat diet and high-fat diet combined with intraperitoneal injection of vitamin D3, respectively. The aortic plaque and pathological changes were used to evaluate AS. Lipid levels, H&E staining and oil red O staining were used to evaluate liver lipid accumulation. The cholesterol metabolism and bile acid excretion were evaluated by enzyme-linked immunosorbent assay, UPLC-QQQ/MS. In vitro, the lipid and FXR/bile salt export pump (BSEP) levels were evaluated by oil red O staining, real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting.

RESULTS

A total of 36 ingredients in DSY were identified by UPLC-MS/MS analysis. In vivo, high-dose DSY significantly inhibited aortic intimal thickening, improved arrangement disorder, tortuosity, and rupture of elastic fibers, decreased lipid levels, and reduced the number of fat vacuoles and lipid droplets in liver tissue in SD rats and ApoE-/- mice. Further studies found that high-dose DSY significantly reduced liver lipid and total bile acids levels, increased liver ursodeoxycholic acid (UDCA) and other non-conjugated bile acids levels, increased fecal total cholesterol (TC) levels, and augmented FXR, BSEP, cholesterol 7-alpha hydroxylase (CYP7A1), ATP binding cassette subfamily G5/G8 (ABCG5/8) expression levels, while decreasing ASBT expression levels. In vitro studies showed that DSY significantly reduced TC and TG levels, as well as lipid droplets, while also increasing the expression of ABCG5/8, FXR, and BSEP in both HepG2 and Nr1h4 knockdown HepG2 cells.

CONCLUSION

This study demonstrated that DSY promotes bile acid metabolism and excretion to prevent AS by activating FXR. For the prevent of AS and drug discovery provided experimental basis.

Cilofexor in Patients With Compensated Cirrhosis Due to Primary Sclerosing Cholangitis: An Open-Label Phase 1B Study

INTRODUCTION

This proof-of-concept, open-label phase 1b study evaluated the safety and efficacy of cilofexor, a potent selective farnesoid X receptor agonist, in patients with compensated cirrhosis due to primary sclerosing cholangitis.

METHODS

Escalating doses of cilofexor (30 mg [weeks 1-4], 60 mg [weeks 5-8], 100 mg [weeks 9-12]) were administered orally once daily over 12 weeks. The primary endpoint was safety. Exploratory measures included cholestasis and fibrosis markers and pharmacodynamic biomarkers of bile acid homeostasis.

RESULTS

Eleven patients were enrolled (median age: 48 years; 55% men). The most common treatment-emergent adverse events (TEAEs) were pruritus (8/11 [72.7%]), fatigue, headache, nausea, and upper respiratory tract infection (2/11 [18.2%] each). Seven patients experienced a pruritus TEAE (one grade 3) considered drug-related. One patient temporarily discontinued cilofexor owing to peripheral edema. There were no deaths, serious TEAEs, or TEAEs leading to permanent discontinuation. Median changes (interquartile ranges) from baseline to week 12 (predose, fasting) were -24.8% (-35.7 to -7.4) for alanine transaminase, -13.0% (-21.9 to -8.6) for alkaline phosphatase, -43.5% (-52.1 to -30.8) for γ-glutamyl transferase, -12.7% (-25.0 to 0.0) for total bilirubin, and -21.2% (-40.0 to 0.0) for direct bilirubin. Least-squares mean percentage change (95% confidence interval) from baseline to week 12 at trough was -55.3% (-70.8 to -31.6) for C4 and -60.5% (-81.8 to -14.2) for cholic acid. Fasting fibroblast growth factor 19 levels transiently increased after cilofexor administration.

DISCUSSION

Escalating doses of cilofexor over 12 weeks were well tolerated and improved cholestasis markers in patients with compensated cirrhosis due to primary sclerosing cholangitis (NCT04060147).

Feeding gut microbes to nourish the brain: unravelling the diet-microbiota-gut-brain axis

The prevalence of brain disorders, including stress-related neuropsychiatric disorders and conditions with cognitive dysfunction, is rising. Poor dietary habits contribute substantially to this accelerating trend. Conversely, healthy dietary intake supports mood and cognitive performance. Recently, the communication between the microorganisms within the gastrointestinal tract and the brain along the gut-brain axis has gained prominence as a potential tractable target to modulate brain health. The composition and function of the gut microbiota is robustly influenced by dietary factors to alter gut-brain signalling. To reflect this interconnection between diet, gut microbiota and brain functioning, we propose that a diet-microbiota-gut-brain axis exists that underpins health and well-being. In this Review, we provide a comprehensive overview of the interplay between diet and gut microbiota composition and function and the implications for cognition and emotional functioning. Important diet-induced effects on the gut microbiota for the development, prevention and maintenance of neuropsychiatric disorders are described. The diet-microbiota-gut-brain axis represents an uncharted frontier for brain health diagnostics and therapeutics across the lifespan.

Perfluoropolyether-Based Gut-Liver-on-a-Chip for the Evaluation of First-Pass Metabolism and Oral Bioavailability of Drugs

In the evolving field of drug discovery and development, multiorgans-on-a-chip and microphysiological systems are gaining popularity owing to their ability to emulate in vivo biological environments. Among the various gut-liver-on-a-chip systems for studying oral drug absorption, the chip developed in this study stands out with two distinct features: incorporation of perfluoropolyether (PFPE) to effectively mitigate drug sorption and a unique enterohepatic single-passage system, which simplifies the analysis of first-pass metabolism and oral bioavailability. By introducing a bolus drug injection into the liver compartment, hepatic extraction alone could be evaluated, further enhancing our estimation of intestinal availability. In a study on midazolam (MDZ), PFPE-based chips showed more than 20-times the appearance of intact MDZ in the liver compartment effluent compared to PDMS-based counterparts. Notably, saturation of hepatic metabolism at higher concentrations was confirmed by observations when the dose was reduced from 200 μM to 10 μM. This result was further emphasized when the metabolism was significantly inhibited by the coadministration of ketoconazole. Our chip, which is designed to minimize the dead volume between the gut and liver compartments, is adept at sensitively observing the saturation of metabolism and the effect of inhibitors. Using genome-edited CYP3A4/UGT1A1-expressing Caco-2 cells, the estimates for intestinal and hepatic availabilities were 0.96 and 0.82, respectively; these values are higher than the known human in vivo values. Although the metabolic activity in each compartment can be further improved, this gut-liver-on-a-chip can not only be used to evaluate oral bioavailability but also to carry out individual assessment of both intestinal and hepatic availability.

New advances in drug development for metabolic dysfunction-associated diseases and alcohol-associated liver disease

Metabolic disorders are currently threatening public health worldwide. Discovering new targets and developing promising drugs will reduce the global metabolic-related disease burden. Metabolic disorders primarily consist of lipid and glucose metabolic disorders. Specifically, metabolic dysfunction-associated steatosis liver disease (MASLD) and alcohol-associated liver disease (ALD) are two representative lipid metabolism disorders, while diabetes mellitus is a typical glucose metabolism disorder. In this review, we aimed to summarize the new drug candidates with promising efficacy identified in clinical trials for these diseases. These drug candidates may provide alternatives for patients with metabolic disorders and advance the progress of drug discovery for the large disease burden.

Regulating bile acids signaling for NAFLD: molecular insights and novel therapeutic interventions

Nonalcoholic fatty liver disease (NAFLD) emerges as the most predominant cause of liver disease, tightly linked to metabolic dysfunction. Bile acids (BAs), initially synthesized from cholesterol in the liver, undergo further metabolism by gut bacteria. Increasingly acknowledged as critical modulators of metabolic processes, BAs have been implicated as important signaling molecules. In this review, we will focus on the mechanism of BAs signaling involved in glucose homeostasis, lipid metabolism, energy expenditure, and immune regulation and summarize their roles in the pathogenesis of NAFLD. Furthermore, gut microbiota dysbiosis plays a key role in the development of NAFLD, and the interactions between BAs and intestinal microbiota is elucidated. In addition, we also discuss potential therapeutic strategies for NAFLD, including drugs targeting BA receptors, modulation of intestinal microbiota, and metabolic surgery.

Activation of TGR5 Increases Urine Concentration by Inducing AQP2 and AQP3 Expression in Renal Medullary Collecting Ducts

Introduction

G protein-coupled bile acid receptor (TGR5), the first G protein-coupled receptor for bile acids identified, is capable of activating a variety of intracellular signaling pathways after interacting with bile acids. TGR5 plays an important role in multiple physiological processes and is considered to be a potential target for the treatment of various metabolic diseases, including type 2 diabetes. Evidence has emerged that genetic deletion of TGR5 results in an increase in basal urine output, suggesting that it may play a critical role in renal water and salt reabsorption. The present study aims to elucidate the effect and mechanism of TGR5 activation on urine concentration.

Methods

Mice were treated with TGR5 agonists (LCA and INT-777) for 3 days. The 24-h urine of mice was collected and analyzed for urine biochemical parameters. The mRNA expressions were detected by real-time PCR, and the protein expressions were detected by western blot. Immunohistochemistry and immunofluorescence were performed to examine the cellular location of proteins. The cultured primary medullary collecting duct cells were pretreated with H89 (a PKA inhibitor) for 1 h, followed by 12-h treatment of LCA and INT-777. Luciferase reporter assays were used to detect the effect of CREB on the gene transcription of AQPs. Gel electrophoretic mobility shift assays were used to analyze DNA-protein interactions.

Results

Treatment of mice with the TGR5 agonist LCA and INT-777 markedly reduced urine output and increased urine osmolality, accompanied by a marked increase in AQP2 and AQP3 protein expression and membrane translocation. In cultured primary medullary collecting duct cells, LCA and INT-777 dose-dependently upregulated AQP2 and AQP3 expression in a cAMP/PKA-dependent manner. Mechanistically, both AQP2 and AQP3 gene promoter contains a putative CREB-binding site, which can be bound and activated by CREB as assessed by both gene promoter-driven luciferase and gel shift assays.

Conclusion

Collectively, our findings demonstrate that activation of TGR5 can promote urine concentration by upregulation of AQP2 and AQP3 expression in renal collecting ducts. TGR5 may represent an attractive target for the treatment of patients with urine concentration defect.

Treatment in primary biliary cholangitis: Beyond ursodeoxycholic acid

Primary biliary cholangitis (PBC) is a rare cholestatic immune-mediated liver disease. The clinical course varies from mild to severe, with a substantial group of patients developing cirrhosis within a decade. These patients are at risk of hepatocellular carcinoma, decompensation and liver failure. First line Ursodeoxycholic acid (UDCA) treatment improves the cholestatic surrogate markers, and was recently associated with a favorable survival free of liver transplantation, even in case of an incomplete biochemical response. However, despite adequate UDCA therapy, patients remain at risk of liver disease progression. Therefore, on-treatment multifactor-based risk stratification is necessary to identify patients in need of additional therapy. This requires a personalized approach; especially as recent studies suggest that complete biochemical normalization as most stringent response criterion might be preferred in selected patients to optimize their outcome. Today, stricter biochemical goals might actually be reachable with the addition of farnesoid X receptor or peroxisome proliferator-activated receptor agonists, or, in highly-selected cases, use of corticosteroids. Randomized controlled trials showed improvements in the key biochemical surrogate markers with the addition of these drugs, which have also been associated with improved clinical outcome. Considering this evolving PBC landscape, with more versatile treatment options and treatment goals, this review recapitulates the recent insight in UDCA therapy, the selection of patients with a residual risk of liver disease progression and the results of the currently available second line treatment options.

New insights into the regulation of bile acids synthesis during the early stages of liver regeneration: A human and experimental study

BACKGROUND AND AIMS

Liver regeneration is essential for the preservation of homeostasis and survival. Bile acids (BAs)-mediated signaling is necessary for liver regeneration, but BAs levels need to be carefully controlled to avoid hepatotoxicity. We studied the early response of the BAs-fibroblast growth factor 19 (FGF19) axis in healthy individuals undergoing hepatectomy for living donor liver transplant. We also evaluated BAs synthesis in mice upon partial hepatectomy (PH) and acute inflammation, focusing on the regulation of cytochrome-7A1 (CYP7A1), a key enzyme in BAs synthesis from cholesterol.

METHODS

Serum was obtained from twelve human liver donors. Mice underwent 2/3-PH or sham-operation. Acute inflammation was induced with bacterial lipopolysaccharide (LPS) in mice fed control or antoxidant-supplemented diets. BAs and 7α-hydroxy-4-cholesten-3-one (C4) levels were measured by HPLC-MS/MS; serum FGF19 by ELISA. Gene expression and protein levels were analyzed by RT-qPCR and western-blot.

RESULTS

Serum BAs levels increased after PH. In patients with more pronounced hypercholanemia, FGF19 concentrations transiently rose, while C4 levels (a readout of CYP7A1 activity) dropped 2 h post-resection in all cases. Serum BAs and C4 followed the same pattern in mice 1 h after PH, but C4 levels also dropped in sham-operated and LPS-treated animals, without marked changes in CYP7A1 protein levels. LPS-induced serum C4 decline was attenuated in mice fed an antioxidant-supplemented diet.

CONCLUSIONS

In human liver regeneration FGF19 upregulation may constitute a protective response from BAs excess during liver regeneration. Our findings suggest the existence of post-translational mechanisms regulating CYP7A1 activity, and therefore BAs synthesis, independent from CYP7A1/Cyp7a1 gene transcription.

Role of the microbiota-gut-heart axis between bile acids and cardiovascular disease

Bile acid (BA) receptors (e.g., farnesoid X-activated receptor, muscarinic receptor) are expressed in cardiomyocytes, endothelial cells, and vascular smooth muscle cells, indicating the relevance of BAs to cardiovascular disease (CVD). Hydrophobic BAs are cardiotoxic, while hydrophilic BAs are cardioprotective. For example, fetal cardiac insufficiency in maternal intrahepatic cholestasis during pregnancy, and the degree of fetal cardiac abnormality, is closely related to the level of hydrophobic BAs in maternal blood and infant blood. However, ursodeoxycholic acid (the most hydrophilic BA) can reverse/prevent these detrimental effects of increased levels of hydrophobic BAs on the heart. The gut microbiota (GM) and GM metabolites (especially secondary BAs) have crucial roles in hypertension, atherosclerosis, unstable angina, and heart failure. Herein, we describe the relationship between CVD and the GM at the BA level. We combine the concept of the "microbiota-gut-heart axis" (MGHA) and postulate the role and mechanism of BAs in CVD development. In addition, the strategies for treating CVD with BAs under the MGHA are proposed.

Parenteral nutrition-associated liver injury: clinical relevance and mechanistic insights

Intestinal failure-associated liver disease (IFALD) is a relatively common complication in individuals receiving parenteral nutrition (PN). IFALD can be manifested as different types of liver injury, including steatosis, cholestasis, and fibrosis, and could result in liver failure in some cases. The onset and progression of IFALD are highly dependent on various patient and PN-related risk factors. Despite still being under investigation, several mechanisms have been proposed. Liver injury can originate due to caloric overload, nutrient deficiency, and toxicity, as well as phytosterol content, and omega-6 to omega-3 fatty acids ratio contained in lipid emulsions. Additional mechanisms include immature or defective bile acid metabolism, acute heart failure, infections, and sepsis exerting negative effects via Toll-like receptor 4 and nuclear factor κB inflammatory signaling. Furthermore, lack of enteral feeding, gut dysbiosis, and altered enterohepatic circulation that affect the farnesoid x receptor-fibroblast growth factor 19 axis can also contribute to IFALD. Various best practices can be adopted to minimize the risk of developing IFALD, such as prevention and management of central line infections and sepsis, preservation of intestine's length, a switch to oral and enteral feeding, cyclic PN, avoidance of overfeeding and soybean oil-based lipid formulations, and avoiding hepatotoxic substances. The present review thus provides a comprehensive overview of all relevant aspects inherent to IFALD. Further research focused on clinical observations, translational models, and advanced toxicological knowledge frameworks is needed to gain more insight into the molecular pathogenesis of hepatotoxicity, reduce IFALD incidence, and encourage the safe use of PN.

Protective Mechanism of Eurotium amstelodami from Fuzhuan Brick Tea against Colitis and Gut-Derived Liver Injury Induced by Dextran Sulfate Sodium in C57BL/6 Mice

The study explored the potential protective impact of the probiotic fungus Eurotium amstelodami in Fuzhuan brick tea on ulcerative colitis, along with the underlying mechanism. A spore suspension of E. amstelodami was administered to C57BL/6 mice to alleviate DSS-induced colitis. The findings indicated that administering E. amstelodami evidently enhanced the ultrastructure of colonic epithelium, showing characteristics such as enhanced TJ length, reduced microvilli damage, and enlarged intercellular space. After HLL supplementation, the activation of the liver inflammation pathway, including TLR4/NF-kB and NLRP3 inflammasome caused by DSS, was significantly suppressed, and bile acid metabolism, linking liver and gut, was enhanced, manifested by restoration of bile acid receptor (FXR, TGR5) level. The dysbiosis of the gut microbes in colitis mice was also restored by HLL intervention, characterized by the enrichment of beneficial bacteria (Lactobacillus, Bifidobacterium, Akkermansia, and Faecalibaculum) and fungi (Aspergillus, Trichoderma, Wallemia, Eurotium, and Cladosporium), which was closely associated with lipid metabolism and amino acid metabolism, and was negatively correlated with inflammatory gene expression. Hence, the recovery of gut microbial community structure, implicated deeply in the inflammatory index and metabolites profile, might play a crucial role in the therapeutic mechanism of HLL on colitis.

Hammerhead-type FXR agonists induce an enhancer RNA Fincor that ameliorates nonalcoholic steatohepatitis in mice

The nuclear receptor, farnesoid X receptor (FXR/NR1H4), is increasingly recognized as a promising drug target for metabolic diseases, including nonalcoholic steatohepatitis (NASH). Protein-coding genes regulated by FXR are well known, but whether FXR also acts through regulation of long non-coding RNAs (lncRNAs), which vastly outnumber protein-coding genes, remains unknown. Utilizing RNA-seq and global run-on sequencing (GRO-seq) analyses in mouse liver, we found that FXR activation affects the expression of many RNA transcripts from chromatin regions bearing enhancer features. Among these we discovered a previously unannotated liver-enriched enhancer-derived lncRNA (eRNA), termed FXR-induced non-coding RNA (Fincor). We show that Fincor is specifically induced by the hammerhead-type FXR agonists, including GW4064 and tropifexor. CRISPR/Cas9-mediated liver-specific knockdown of Fincor in dietary NASH mice reduced the beneficial effects of tropifexor, an FXR agonist currently in clinical trials for NASH and primary biliary cholangitis (PBC), indicating that amelioration of liver fibrosis and inflammation in NASH treatment by tropifexor is mediated in part by Fincor. Overall, our findings highlight that pharmacological activation of FXR by hammerhead-type agonists induces a novel eRNA, Fincor, contributing to the amelioration of NASH in mice. Fincor may represent a new drug target for addressing metabolic disorders, including NASH.

Intestinal FGF15 regulates bile acid and cholesterol metabolism but not glucose and energy balance

Fibroblast growth factor 15/19 (FGF15/19, mouse/human ortholog) is expressed in the ileal enterocytes of the small intestine and released postprandially in response to bile acid absorption. Previous reports of FGF15-/- mice have limited our understanding of gut-specific FGF15's role in metabolism. Therefore, we studied the role of endogenous gut-derived FGF15 in bile acid, cholesterol, glucose, and energy balance. We found that circulating levels of FGF19 were reduced in individuals with obesity and comorbidities, such as type 2 diabetes and metabolic dysfunction-associated fatty liver disease. Gene expression analysis of ileal FGF15-positive cells revealed differential expression during the obesogenic state. We fed standard chow or a high-fat metabolic dysfunction-associated steatohepatitis-inducing diet to control and intestine-derived FGF15-knockout (FGF15INT-KO) mice. Control and FGF15INT-KO mice gained similar body weight and adiposity and did not show genotype-specific differences in glucose, mixed meal, pyruvate, and glycerol tolerance. FGF15INT-KO mice had increased systemic bile acid levels but decreased cholesterol levels, pointing to a primary role for gut-derived FGF15 in regulating bile acid and cholesterol metabolism when exposed to obesogenic diet. These studies show that intestinal FGF15 plays a specific role in bile acid and cholesterol metabolism regulation but is not essential for energy and glucose balance.

Natural history of metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD), which has been the term for non-alcoholic fatty liver disease (NAFLD) since June 2023, represents the most common liver disease worldwide and is a leading cause of liver-related morbidity and mortality. A thorough knowledge of the disease's natural history is required to promptly stratify patients' risks, since MASLD is a multifaceted disorder with a broad range of clinical phenotypes. The histological disease spectrum ranges from isolated hepatic steatosis, currently named as metabolic dysfunction-associated steatotic liver (MASL), to metabolic dysfunction-associated steatohepatitis (MASH) and eventually may accumulate hepatic fibrosis and develop cirrhosis and/or hepatocellular carcinoma (HCC). Several risk factors for fibrosis progression have been identified, while the disease's progression displays notable dynamism and bidirectionality. When compared to the general population, all MASLD histological stages are substantially related with greater overall mortality, and this association exhibits a disease severity-dependent pattern. Interestingly, the fibrosis stage is the most accurate predictor of mortality among MASLD patients. The mortality attributed to MASLD predominantly stems from issues linked with the liver and cardiovascular system, as well as HCC and extrahepatic cancers. In light of the disease natural course, it is crucial to prioritize the identification of at-risk patients for disease progression in order to effectively address and change modifiable risk factors, hence mitigating disease complications. Further investigation is required to define the phenotype of rapid progressors more precisely as well as to improve risk stratification for HCC in non-cirrhotic individuals.

Novel preclinical developments of the primary sclerosing cholangitis treatment landscape

INTRODUCTION

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease associated with inflammation, fibrosis, and destruction of intra- and extrahepatic bile ducts. Despite substantial recent advances in our understanding of PSC, the only proven treatment of PSC is liver transplantation. There is an urgent unmet need to find medical therapies for this disorder.

AREAS COVERED

Multiple drugs are currently under evaluation as therapeutic options for this disease. This article summarizes the literature on the various novel therapeutic options that have been investigated and are currently under development for the treatment of PSC.

EXPERT OPINION

In the next decade, more than one drug will likely be approved for the treatment of the disease, and we will be looking at combination therapies for the optimal management of the disease.

The bile-gut axis and metabolic consequences of cholecystectomy

Cholelithiasis and cholecystitis affect individuals of all ages and are often treated by surgical removal of the gallbladder (cholecystectomy), which is considered a safe, low-risk procedure. Nevertheless, recent findings show that bile and its regulated storage and excretion may have important metabolic effects and that cholecystectomy is associated with several metabolic diseases postoperatively. Bile acids have long been known as emulsifiers essential to the assimilation of lipids and absorption of lipid-soluble vitamins, but more recently, they have also been reported to act as metabolic signaling agents. The nuclear receptor, farnesoid X receptor (FXR), and the G protein-coupled membrane receptor, Takeda G protein-coupled receptor 5 (TGR5), are specific to bile acids. Through activation of these receptors, bile acids control numerous metabolic functions. Cholecystectomy affects the storage and excretion of bile acids, which in turn may influence the activation of FXR and TGR5 and their effects on metabolism including processes leading to metabolic conditions such as metabolic dysfunction-associated steatotic liver disease and metabolic syndrome. Here, with the aim of elucidating mechanisms behind cholecystectomy-associated dysmetabolism, we review studies potentially linking cholecystectomy and bile acid-mediated metabolic effects and discuss possible pathophysiological mechanisms behind cholecystectomy-associated dysmetabolism.

Determination of Bile Acids in Canine Biological Samples: Diagnostic Significance

The comprehensive examination of bile acids is of paramount importance across various fields of health sciences, influencing physiology, microbiology, internal medicine, and pharmacology. While enzymatic reaction-based photometric methods remain fundamental for total BA measurements, there is a burgeoning demand for more sophisticated techniques such as liquid chromatography-tandem mass spectrometry (LC-MS/MS) for comprehensive BA profiling. This evolution reflects a need for nuanced diagnostic assessments in clinical practice. In canines, a BA assessment involves considering factors, such as food composition, transit times, and breed-specific variations. Multiple matrices, including blood, feces, urine, liver tissue, and gallbladder bile, offer insights into BA profiles, yet interpretations remain complex, particularly in fecal analysis due to sampling challenges and breed-specific differences. Despite ongoing efforts, a consensus regarding optimal matrices and diagnostic thresholds remains elusive, highlighting the need for further research. Emphasizing the scarcity of systematic animal studies and underscoring the importance of ap-propriate sampling methodologies, our review advocates for targeted investigations into BA alterations in canine pathology, promising insights into pathomechanisms, early disease detection, and therapeutic avenues.

Skin advanced glycation end-products as indicators of the metabolic profile in diabetes mellitus: correlations with glycemic control, liver phenotypes and metabolic biomarkers

INTRODUCTION

The production of advanced glycation end-products (AGEs) is a key pathomechanism related to the complications of diabetes mellitus. The measurement of HbA1c as one of the AGEs is widely used in the clinic, but also other proteins undergo glycation in the course of diabetes. Here, we measure skin AGEs (SAGEs) in patients with diabetes type 1 (DM1) and type 2 (DM2) and correlate them with metabolic markers as well as non-invasively measured liver fibrosis and steatosis.

PATIENTS AND METHODS

In this cross-sectional study, a total of 64 patients with either DM1 or DM2 and 28 healthy controls were recruited. SAGEs were measured using autofluorescence (AGE Reader). Liver fibrosis and steatosis were quantified using transient elastography, which determines liver stiffness measurement (LSM) and controlled attenuation parameter (CAP). FGF19, FGF21 and GDF-15 were measured in blood samples using ELISA.

RESULTS

SAGEs were elevated in both groups of patients with diabetes as compared to healthy controls (both p < 0.001) and were higher in patients with DM2 in comparison to DM1 (p = 0.006). SAGEs correlated positively with HbA1c (r = 0.404, p < 0.001), CAP (r = 0.260, p = 0.016) and LSM (r = 0.356, p < 0.001), and negatively with insulin growth factor binding protein 3 (p < 0.001). We also detected a positive correlation between GDF15 and SAGEs (r = 0.469, p < 0.001).

CONCLUSIONS

SAGEs are significantly elevated in patients with both DM types 1 and 2 and correlate with metabolic markers, including HbA1c and GDF15. They might also help to detect patients with advanced liver injury in the setting of diabetes.

Diagnosis, Management, and Prognosis of Cystic Fibrosis-Related Liver Disease in Children

Cystic fibrosis (CF) is a multifaceted disorder predominantly investigated for its pulmonary manifestations, yet patients with CF also exhibit a spectrum of extrapulmonary manifestations, notably those involving the hepatobiliary system. The latter constitutes the third leading cause of morbidity and mortality in individuals with CF. Cystic fibrosis-related liver disease (CFLD), with an escalating prevalence, manifests diverse clinical presentations ranging from hepatomegaly to cirrhosis and hepatopulmonary syndrome. Consequently, early detection and appropriate management are imperative for sustaining the health and influencing the quality of life of CF patients afflicted with CFLD. This review aims to consolidate existing knowledge by providing a comprehensive overview of hepatobiliary manifestations associated with CF. It delineates the clinical hepatobiliary manifestations, diagnostic methodologies, incorporating minimally invasive markers, and therapeutic approaches, encompassing the impact of novel CFTR modulators on CFLD. Given the exigency of early diagnosis and the intricate management of CFLD, a multidisciplinary team approach is essential to optimize care and enhance the quality of life for this subset of patients. In conclusion, recognizing CF as more than solely a pulmonary ailment, the authors underscore the imperative for further clinical investigations to establish a more robust evidence base for CFLD management within the continuum of this chronic disease.

Hammerhead-type FXR agonists induce an eRNA FincoR that ameliorates nonalcoholic steatohepatitis in mice

The nuclear receptor, Farnesoid X Receptor (FXR/NR1H4), is increasingly recognized as a promising drug target for metabolic diseases, including nonalcoholic steatohepatitis (NASH). Protein coding genes regulated by FXR are well known, but whether FXR also acts through regulation of long non-coding RNAs (lncRNAs), which vastly outnumber protein-coding genes, remains unknown. Utilizing RNA-seq and GRO-seq analyses in mouse liver, we found that FXR activation affects the expression of many RNA transcripts from chromatin regions bearing enhancer features. Among these we discovered a previously unannotated liver-enriched enhancer-derived lncRNA (eRNA), termed FincoR. We show that FincoR is specifically induced by the hammerhead-type FXR agonists, including GW4064 and tropifexor. CRISPR/Cas9-mediated liver-specific knockdown of FincoR in dietary NASH mice reduced the beneficial effects of tropifexor, an FXR agonist currently in clinical trials for NASH and primary biliary cholangitis (PBC), indicating that that amelioration of liver fibrosis and inflammation in NASH treatment by tropifexor is mediated in part by FincoR. Overall, our findings highlight that pharmacological activation of FXR by hammerhead-type agonists induces a novel eRNA, FincoR, contributing to the amelioration of NASH in mice. FincoR may represent a new drug target for addressing metabolic disorders, including NASH.

Bifidobacterium animalis subsp. lactis F1-7 Alleviates Lipid Accumulation in Atherosclerotic Mice via Modulating Bile Acid Metabolites to Downregulate Intestinal FXR

The dysfunction of intestinal microbiota and bile acid metabolism is related to the pathogenesis of atherosclerosis. This study we explored the mechanism of Bifidobacterium animalis subsp. lactis F1-7 (Bif. animalis F1-7), improving atherosclerosis by regulating the bile acid metabolism and intestinal microbiota in the ApoE-/- mice. The Bif. animalis F1-7 effectively reduced aortic plaque accumulation and improved the serum and liver lipid levels in atherosclerotic mice. The untargeted metabolomics revealed that Bif. animalis F1-7 reduced the glycine-conjugated bile acids and the levels of differential metabolite lithocholic acid (LCA) significantly. Downregulation of LCA decreased the intestinal levels of the farnesoid X-activated receptor (FXR) and regulated the bile acid metabolism through the FXR/FGF15/CYP7A1 pathway. Furthermore, the 16srRNA gene sequencing analysis revealed that structural changes in intestinal microbiota with an increase in the abundance of Bifidobacterium, Lactobacillus, Faecalibaculum, Desulfovibrio, and a decrease in Dubosiella, Clostridium_sensu_stricto_1, and Turicibacter following the Bif. animalis F1-7 intervention. Correlation analysis showed that the changes in intestinal microbiota mentioned above were significantly correlated with bile acid metabolism in atherosclerotic mice. In conclusion, this study sheds light on the mechanisms by which Bif. animalis F1-7 regulates atherosclerosis.

Gut commensal Christensenella minuta modulates host metabolism via acylated secondary bile acids

A strong correlation between gut microbes and host health has been observed in numerous gut metagenomic cohort studies. However, the underlying mechanisms governing host-microbe interactions in the gut remain largely unknown. Here we report that the gut commensal Christensenella minuta modulates host metabolism by generating a previously undescribed class of secondary bile acids with 3-O-acylation substitution that inhibit the intestinal farnesoid X receptor. Administration of C. minuta alleviated features of metabolic disease in high fat diet-induced obese mice associated with a significant increase in these acylated bile acids, which we refer to as 3-O-acyl-cholic acids. Specific knockout of intestinal farnesoid X receptor in mice counteracted the beneficial effects observed in their wild-type counterparts. Finally, we showed that 3-O-acyl-CAs were prevalent in healthy humans but significantly depleted in patients with type 2 diabetes. Our findings indicate a role for C. minuta and acylated bile acids in metabolic diseases.

Endocrine FGFs and their signaling in the brain: Relevance for energy homeostasis

Since their discovery in 2000, there has been a continuous expansion of studies investigating the physiology, biochemistry, and pharmacology of endocrine fibroblast growth factors (FGFs). FGF19, FGF21, and FGF23 comprise a subfamily with attributes that distinguish them from typical FGFs, as they can act as hormones and are, therefore, referred to as endocrine FGFs. As they participate in a broad cross-organ endocrine signaling axis, endocrine FGFs are crucial lipidic, glycemic, and energetic metabolism regulators during energy availability fluctuations. They function as powerful metabolic signals in physiological responses induced by metabolic diseases, like type 2 diabetes and obesity. Pharmacologically, FGF19 and FGF21 cause body weight loss and ameliorate glucose homeostasis and energy expenditure in rodents and humans. In contrast, FGF23 expression in mice and humans has been linked with insulin resistance and obesity. Here, we discuss emerging concepts in endocrine FGF signaling in the brain and critically assess their putative role as therapeutic targets for treating metabolic disorders.

The Role of Nuclear Receptors in the Pathogenesis and Treatment of Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a global health burden closely linked to insulin resistance, obesity, and type 2 diabetes. The complex pathophysiology of NAFLD involves multiple cellular pathways and molecular factors. Nuclear receptors (NRs) have emerged as crucial regulators of lipid metabolism and inflammation in NAFLD, offering potential therapeutic targets for NAFLD. Targeting PPARs and FXRs has shown promise in ameliorating NAFLD symptoms and halting disease progression. However, further investigation is needed to address side effects and personalize therapy approaches. This review summarizes the current understanding of the involvement of NRs in the pathogenesis of NAFLD and explores their therapeutic potential. We discuss the role of several NRs in modulating lipid homeostasis in the liver, including peroxisome proliferator-activated receptors (PPARs), liver X receptors (LXRs), farnesoid X receptors (FXRs), REV-ERB, hepatocyte nuclear factor 4α (HNF4α), constitutive androstane receptor (CAR) and pregnane X receptor (PXR).The expanding knowledge of NRs in NAFLD offers new avenues for targeted therapies, necessitating exploration of novel treatment strategies and optimization of existing approaches to combat this increasingly prevalent disease.

Lysine tRNA fragments and miR-194-5p co-regulate hepatic steatosis via β-Klotho and perilipin 2

OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) involves hepatic accumulation of intracellular lipid droplets via incompletely understood processes. Here, we report distinct and cooperative NAFLD roles of LysTTT-5'tRF transfer RNA fragments and microRNA miR-194-5p.

METHODS

Combined use of diet induced obese mice with human-derived oleic acid-exposed Hep G2 cells revealed new NAFLD roles of LysTTT-5'tRF and miR-194-5p.

RESULTS

Unlike lean animals, dietary-induced NAFLD mice showed concurrent hepatic decrease of both LysTTT-5'tRF and miR-194-5p levels, which were restored following miR-132 antisense oligonucleotide treatment which suppresses hepatic steatosis. Moreover, exposing human-derived Hep G2 cells to oleic acid for 7 days co-suppressed miR-194-5p and LysTTT-5'tRF levels while increasing lipid accumulation. Inversely, transfecting fattened cells with a synthetic LysTTT-5'tRF mimic elevated mRNA levels of the metabolic regulator β-Klotho while decreasing triglyceride amounts by 30% within 24 h. In contradistinction, antisense suppression of miR-194-5p induced accumulation of its novel target, the NAFLD-implicated lipid droplet-coating PLIN2 protein. Further, two out of 15 steatosis-alleviating screened drug-repurposing compounds, Danazol and Latanoprost, elevated miR-194-5p or LysTTT-5'tRF levels.

CONCLUSION

Our findings highlight the different yet complementary roles of miR-194-5p and LysTTT-5'tRF and offer new insights into the complex roles of small non-coding RNAs and the multiple pathways involved in NAFLD pathogenesis.

Modulating a prebiotic food source influences inflammation and immune-regulating gut microbes and metabolites: insights from the BE GONE trial

BACKGROUND

Accessible prebiotic foods hold strong potential to jointly target gut health and metabolic health in high-risk patients. The BE GONE trial targeted the gut microbiota of obese surveillance patients with a history of colorectal neoplasia through a straightforward bean intervention.

METHODS

This low-risk, non-invasive dietary intervention trial was conducted at MD Anderson Cancer Center (Houston, TX, USA). Following a 4-week equilibration, patients were randomized to continue their usual diet without beans (control) or to add a daily cup of study beans to their usual diet (intervention) with immediate crossover at 8-weeks. Stool and fasting blood were collected every 4 weeks to assess the primary outcome of intra and inter-individual changes in the gut microbiome and in circulating markers and metabolites within 8 weeks. This study was registered on ClinicalTrials.gov as NCT02843425, recruitment is complete and long-term follow-up continues.

FINDINGS

Of the 55 patients randomized by intervention sequence, 87% completed the 16-week trial, demonstrating an increase on-intervention in diversity [n = 48; linear mixed effect and 95% CI for inverse Simpson index: 0.16 (0.02, 0.30); p = 0.02] and shifts in multiple bacteria indicative of prebiotic efficacy, including increased Faecalibacterium, Eubacterium and Bifidobacterium (all p < 0.05). The circulating metabolome showed parallel shifts in nutrient and microbiome-derived metabolites, including increased pipecolic acid and decreased indole (all p < 0.002) that regressed upon returning to the usual diet. No significant changes were observed in circulating lipoproteins within 8 weeks; however, proteomic biomarkers of intestinal and systemic inflammatory response, fibroblast-growth factor-19 increased, and interleukin-10 receptor-α decreased (p = 0.01).

INTERPRETATION

These findings underscore the prebiotic and potential therapeutic role of beans to enhance the gut microbiome and to regulate host markers associated with metabolic obesity and colorectal cancer, while further emphasizing the need for consistent and sustainable dietary adjustments in high-risk patients.

FUNDING

This study was funded by the American Cancer Society.

The intestine as an endocrine organ and the role of gut hormones in metabolic regulation

Gut hormones orchestrate pivotal physiological processes in multiple metabolically active tissues, including the pancreas, liver, adipose tissue, gut and central nervous system, making them attractive therapeutic targets in the treatment of obesity and type 2 diabetes mellitus. Most gut hormones are derived from enteroendocrine cells, but bioactive peptides that are derived from other intestinal epithelial cell types have also been implicated in metabolic regulation and can be considered gut hormones. A deeper understanding of the complex inter-organ crosstalk mediated by the intestinal endocrine system is a prerequisite for designing more effective drugs that are based on or target gut hormones and their receptors, and extending their therapeutic potential beyond obesity and diabetes mellitus. In this Review, we present an overview of gut hormones that are involved in the regulation of metabolism and discuss their action in the gastrointestinal system and beyond.

Human Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of ASC42, a Novel Farnesoid X Receptor Agonist

BACKGROUND

ASC42 is a non-steroidal farnesoid X receptor agonist currently in clinical development for chronic liver diseases, such as nonalcoholic fatty liver disease/nonalcoholic steatohepatitis (NAFLD/NASH) and primary biliary cirrhosis (PBC).

OBJECTIVE

The objective of this study was to assess the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of ASC42 in healthy subjects.

METHODS

We conducted the first-in-human study of ASC42 following single and multiple ascending doses (SAD/MAD) and food effect in healthy subjects. The SAD study included five cohorts receiving 5-200 mg ASC42 or placebo and one cohort that was given 15 mg ASC42 with a high-fat meal. The MAD study included three cohorts receiving 5-50 mg ASC42 or placebo once-daily (QD) for 14 days.

RESULTS

A total of 65 healthy subjects were enrolled and one subject in the MAD study (cohort 8, ASC42 50 mg) withdrew from the study due to an unrelated serious adverse event (SAE) of atrial fibrillation. Pruritus was observed at the highest doses (200 mg cohort in SAD and 50 mg cohort in MAD). Most AEs were mild or moderate. No life-threatening or fatal AEs occurred. ASC42 showed a proportional increase in exposure and elimination half-life following both single and multiple dosing. There was a 21% and 37% decrease in area under the curve (AUC) and maximum plasma concentration (Cmax) when ASC42 was coadministered with food. The steady state was reached on day 4 with a mild accumulation (1.02-1.74-fold). ASC42 showed dose-dependent increases in fibroblast growth factor 19 and decreases in 7α-hydroxy-4-cholesten-3-one. Cholesterol remained within normal limits during study.

CONCLUSION

ASC42 was well tolerated with a pharmacokinetic profile suitable for QD dosing, and demonstrated dose-dependent targets engagement without altering plasma cholesterol in healthy subjects.

TRIAL REGISTRATION NUMBER

NCT04679129.

Profile of the bile acid FXR-FGF15 pathway in the glucolipid metabolism disorder of diabetic mice suffering from chronic stress

Background

Imbalances in bile acid (BA) synthesis and metabolism are involved in the onset of diabetes and depression in humans and rodents. However, the role of BAs and the farnesoid X receptor (FXR)/fibroblast growth factor (FGF) 15 signaling pathway in the development of diabetes and depression is still largely unknown. Therefore, we investigated the potential molecular mechanisms of BAs that may be associated with glucolipid metabolism disorders in diabetic mice subjected to chronic stress.

Methods

The type 2 diabetes mellitus (T2DM) mouse model was induced by feeding mice a high-fat diet and administering an intraperitoneal injection of streptozotocin (STZ). The chronic unpredictable mild stress (CUMS) procedure was performed by introducing a series of mild stressors. Forty mice were randomly divided into the regular chow feeding group and the high-fat diet feeding group. After two weeks of feeding, the mice were randomly divided into four groups: the Control group, CUMS group, T2DM group, and T2DM+CUMS group. The T2DM group and T2DM+CUMS group received an intraperitoneal injection of STZ to induce the T2DM model. The CUMS and T2DM+CUMS groups were exposed to CUMS to induce depressive-like phenotypes. Blood and tissue samples were obtained for pertinent analysis and detection.

Results

Compared with the T2DM mice, T2DM+CUMS mice had higher blood glucose and lipid levels, insulin resistance, inflammation of the liver and pancreas, impaired liver function, and increased total bile acids. These changes were accompanied by attenuated FXR signaling. Chronic stress was found to attenuate FXR expression and its downstream target, FGF15, in the ileum when compared with the T2DM group.

Conclusion

FXR may play a role in the diabetic disorder of glucolipid metabolism when aggravated by chronic stress. FXR and its downstream target, FGF15, may be therapeutic targets for treating comorbid T2DM and depression.

The gut-liver axis and gut microbiota in health and liver disease

The trillions of microorganisms in the human intestine are important regulators of health, and disruptions in the gut microbial communities can cause disease. The gut, liver and immune system have a symbiotic relationship with these microorganisms. Environmental factors, such as high-fat diets and alcohol consumption, can disrupt and alter microbial communities. This dysbiosis can lead to dysfunction of the intestinal barrier, translocation of microbial components to the liver and development or progression of liver disease. Changes in metabolites produced by gut microorganisms can also contribute to liver disease. In this Review, we discuss the importance of the gut microbiota in maintenance of health and the alterations in microbial mediators that contribute to liver disease. We present strategies for modulation of the intestinal microbiota and/or their metabolites as potential treatments for liver disease.

FXR agonists in NASH treatment

The farnesoid X receptor (FXR), a bile acid (BA)-activated nuclear receptor highly expressed in the liver and intestine, regulates the expression of genes involved in cholesterol and bile acid homeostasis, hepatic gluconeogenesis, lipogenesis, inflammation and fibrosis, in addition to controlling intestinal barrier integrity, preventing bacterial translocation and maintaining gut microbiota eubiosis. Non-alcoholic steatohepatitis (NASH), an advanced stage of non-alcoholic fatty liver disease, is characterized by hepatic steatosis, hepatocyte damage (ballooning) and inflammation, leading to fibrosis, cirrhosis and hepatocellular carcinoma. NASH represents a major unmet medical need, but no pharmacological treatments have yet been approved. The pleiotropic mechanisms involved in NASH development offer a range of therapeutic opportunities and among them FXR activation has emerged as an established pharmacological target. Various FXR agonists with different physicochemical properties, which can be broadly classified as BA derivatives, non-BA-derived steroidal FXR agonists, non-steroidal FXR agonists, and partial FXR agonists, are in advanced clinical development. In this review we will summarize key preclinical and clinical features of the most advanced FXR agonists and critically evaluate their potential in NASH treatment.

Disruption of IL-18 signaling via engineered IL-18BP biologics alleviates experimental cholestatic liver disease

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by progressive inflammation and fibrosis around intrahepatic and extrahepatic bile ducts leading to severe hepatic cirrhosis and high mortality. Although there is an urgent clinical unmet need for PSC, no effective medical therapy has been developed to delay the disease progression until today. IL-18 binding protein (IL-18BP) is well-known to be a natural negative feedback regulator for IL-18, and we have developed a recombinant long-acting IL-18BP referred to as APB-R3 as a therapeutic agent to treat IL-18-related inflammatory diseases. Here, we aimed to study whether disrupted IL-18 signaling by APB-R3 treatment can inhibit PSC injuries in the experimental DDC diet-induced PSC rodent model. First, we found that the amounts of free IL-18 are augmented under PSC condition with increased expression of biliary IL-18 receptors. Administration of APB-R3 effectively attenuated key diagnostic parameters of PSC such as plasma ALP and GGT levels as well as bile acids levels. We also observed that blockade of IL-18 suppressed ductular reactive and proliferative phenotypes of cholangiocytes. Additionally, APB-R3 significantly ameliorated DDC diet-induced periductal fibrosis and transcriptional expressions of pro-fibrotic marker genes. Enhanced senescence associated secretory phenotype (SASP) markers in cholestatic liver disease were diminished by APB-R3 treatment. Our findings clearly demonstrate that the administration of IL-18BP biologics, APB-R3, effectively alleviates DDC diet-induced biliary injuries in rodent PSC model, implying APB-R3 can be a promising therapeutic reagent which warrants clinical human trials as new therapeutic options.

Engineered FGF19ΔKLB protects against intrahepatic cholestatic liver injury in ANIT-induced and Mdr2-/- mice model

BACKGROUND

The major safety concern of the clinical application of wild type FGF19 (FGF19WT) emerges given that its extended treatment causes hepatocellular carcinoma. Therefore, we previously generated a safer FGF19 variant - FGF19ΔKLB, which have same effects on glycemic control and bile acid production but much less mitogenic activity. However, it remains unclear as to whether FGF19ΔKLB ameliorates intrahepatic cholestasis.

RESULTS

We found that, similar to that of FGF19WT, the chronic administration of FGF19ΔKLB protects mice from cholestatic liver injury in these two models. The therapeutic benefits of FGF19ΔKLB on cholestatic liver damage are attributable, according to the following mechanistic investigation, to the reduction of BA production, liver inflammation, and fibrosis. More importantly, FGF19ΔKLB did not induce any tumorigenesis effects during its prolonged treatment.

CONCLUSIONS

Together, our findings raise hope that FGF19ΔKLB may represent a useful therapeutic strategy for the treatment of intrahepatic cholestasis.

Enterobacteriaceae Growth Promotion by Intestinal Acylcarnitines, a Biomarker of Dysbiosis in Inflammatory Bowel Disease

BACKGROUND & AIMS

Altered plasma acylcarnitine levels are well-known biomarkers for a variety of mitochondrial fatty acid oxidation disorders and can be used as an alternative energy source for the intestinal epithelium when short-chain fatty acids are low. These membrane-permeable fatty acid intermediates are excreted into the gut lumen via bile and are increased in the feces of patients with inflammatory bowel disease (IBD).

METHODS

Herein, based on studies in human subjects, animal models, and bacterial cultures, we show a strong positive correlation between fecal carnitine and acylcarnitines and the abundance of Enterobacteriaceae in IBD where they can be consumed by bacteria both in vitro and in vivo.

RESULTS

Carnitine metabolism promotes the growth of Escherichia coli via anaerobic respiration dependent on the cai operon, and acetylcarnitine dietary supplementation increases fecal carnitine levels with enhanced intestinal colonization of the enteric pathogen Citrobacter rodentium.

CONCLUSIONS

In total, these results indicate that the increased luminal concentrations of carnitine and acylcarnitines in patients with IBD may promote the expansion of pathobionts belonging to the Enterobacteriaceae family, thereby contributing to disease pathogenesis.

Peripheral Vascular Disease and Carotid Artery Disease Are Associated with Decreased Bile Acid Excretion

Low bile acid excretion (BAE) is associated with a higher risk of coronary artery disease (CAD) and cerebrovascular disease (stroke). This study investigated BAE in patients with peripheral vascular disease (PVD) and carotid artery disease (CA) and those without these diseases, compared to patients with CAD, stroke, or no evidence of atherosclerosis. Patients with complaints of chest pain-suspected CAD, syncope, stroke/TIA, severe headache, intermittent claudication, or falls were enrolled. All received a 4-day standard diet with 490 mg of cholesterol and internal standard copper thiocyanate. Fecal BAE was measured using gas-liquid chromatography. One hundred and three patients, sixty-eight (66%) men and thirty-five women (34%), mean age range 60.9 ± 8.9 years, were enrolled in this prospective, 22-year follow-up study. Regression analysis showed that advanced age, total BAE, and excretion of the main fractions were the only significant independent factors that predicted prolonged survival (p < 0.001). Twenty-two years' follow-up revealed only 15% of those with BAE <262.4 mg/24 h survived, compared to >60% of participants without atherosclerosis and a mean BAE of 676 mg/24 h. BAE was lower in patients with polyvascular atherosclerosis than in those with involvement of 1-3 vascular beds. Pearson correlations were found between total BAE and various fractions of BA, as well as HDL cholesterol. BAE and short-term survival were decreased among patients with PVD compared to those with CAD or stroke. Low BAE should be considered a valuable and independent risk factor for PVD.

Salt and Gut Microbiota in Heart Failure

PURPOSE OF REVIEW

The role and underlying mechanisms mediated by dietary salt in modulating the gut microbiota and contributing to heart failure (HF) are not clear. This review summarizes the mechanisms of dietary salt and the gut-heart axis in HF.

RECENT FINDINGS

The gut microbiota has been implicated in several cardiovascular diseases (CVDs) including HF. Dietary factors including high consumption of salt play a role in influencing the gut microbiota, resulting in dysbiosis. An imbalance of microbial species due to a reduction in microbial diversity with accompanying immune cell activation has been implicated in the pathogenesis of HF via several mechanisms. The gut microbiota and gut-associated metabolites contribute to HF by reducing gut microbiota biodiversity and activating several signaling pathways. High dietary salt modulates the gut microbiota composition and exacerbate or induce HF by increasing the expression of the epithelial sodium/hydrogen exchanger isoform 3 in the gut, cardiac expression of beta myosin heavy chain, activation of the myocyte enhancer factor/nuclear factor of activated T cell, and salt-inducible kinase 1. These mechanisms explain the resulting structural and functional derangements in patients with HF.

Transgenic mice lacking FGF15/19-SHP phosphorylation display altered bile acids and gut bacteria, promoting nonalcoholic fatty liver disease

Dysregulated bile acid (BA)/lipid metabolism and gut bacteria dysbiosis are tightly associated with the development of obesity and non-alcoholic fatty liver disease (NAFLD). The orphan nuclear receptor, Small Heterodimer Partner (SHP/NR0B2), is a key regulator of BA/lipid metabolism, and its gene-regulating function is markedly enhanced by phosphorylation at Thr-58 mediated by a gut hormone, fibroblast growth factor-15/19 (FGF15/19). To investigate the role of this phosphorylation in whole-body energy metabolism, we generated transgenic SHP-T58A knock-in mice. Compared with wild-type (WT) mice, the phosphorylation-defective SHP-T58A mice gained weight more rapidly with decreased energy expenditure and increased lipid/BA levels. This obesity-prone phenotype was associated with the upregulation of lipid/BA synthesis genes and downregulation of lipophagy/β-oxidation genes. Mechanistically, defective SHP phosphorylation selectively impaired its interaction with LRH-1, resulting in de-repression of SHP/LRH-1 target BA/lipid synthesis genes. Remarkably, BA composition and selective gut bacteria which are known to impact obesity, were also altered in these mice. Upon feeding a high-fat diet, fatty liver developed more severely in SHP-T58A mice compared to WT mice. Treatment with antibiotics substantially improved the fatty liver phenotypes in both groups but had greater effects in the T58A mice so that the difference between the groups was largely eliminated. These results demonstrate that defective phosphorylation at a single nuclear receptor residue can impact whole-body energy metabolism by altering BA/lipid metabolism and gut bacteria, promoting complex metabolic disorders like NAFLD. Since posttranslational modifications generally act in gene- and context-specific manners, the FGF15/19-SHP phosphorylation axis may allow more targeted therapy for NAFLD.

GPCR-mediated effects of fatty acids and bile acids on glucose homeostasis

Fatty acids and glucose are key biomolecules that share several commonalities including serving as energy substrates and as signaling molecules. Fatty acids can be synthesized endogenously from intermediates of glucose catabolism via de-novo lipogenesis. Bile acids are synthesized endogenously in the liver from the biologically important lipid molecule, cholesterol. Evidence abounds that fatty acids and bile acids play direct and indirect roles in systemic glucose homeostasis. The tight control of plasma glucose levels during postprandial and fasted states is principally mediated by two pancreatic hormones, insulin and glucagon. Here, we summarize experimental studies on the endocrine effects of fatty acids and bile acids, with emphasis on their ability to regulate the release of key hormones that regulate glucose metabolism. We categorize the heterogenous family of fatty acids into short chain fatty acids (SCFAs), unsaturated, and saturated fatty acids, and highlight that along with bile acids, these biomolecules regulate glucose homeostasis by serving as endogenous ligands for specific G-protein coupled receptors (GPCRs). Activation of these GPCRs affects the release of incretin hormones by enteroendocrine cells and/or the secretion of insulin, glucagon, and somatostatin by pancreatic islets, all of which regulate systemic glucose homeostasis. We deduce that signaling induced by fatty acids and bile acids is necessary to maintain euglycemia to prevent metabolic diseases such as type-2 diabetes and related metabolic disorders.

Metabolic-Associated Fatty Liver Disease and Insulin Resistance: A Review of Complex Interlinks

Metabolic-associated fatty liver disease (MAFLD) has now surpassed alcohol excess as the most common cause of chronic liver disease globally, affecting one in four people. Given its prevalence, MAFLD is an important cause of cirrhosis, even though only a small proportion of patients with MAFLD ultimately progress to cirrhosis. MAFLD suffers as a clinical entity due to its insidious and often asymptomatic onset, lack of an accurate and reliable non-invasive diagnostic test, and lack of a bespoke therapy that has been designed and approved for use specifically in MAFLD. MAFLD sits at a crossroads between the gut and the periphery. The development of MAFLD (including activation of the inflammatory cascade) is influenced by gut-related factors that include the gut microbiota and intactness of the gut mucosal wall. The gut microbiota may interact directly with the liver parenchyma (through translocation via the portal vein), or indirectly through the release of metabolic metabolites that include secondary bile acids, trimethylamine, and short-chain fatty acids (such as propionate and acetate). In turn, the liver mediates the metabolic status of peripheral tissues (including insulin sensitivity) through a complex interplay of hepatokines, liver-secreted metabolites, and liver-derived micro RNAs. As such, the liver plays a key central role in influencing overall metabolic status. In this concise review, we provide an overview of the complex mechanisms whereby MAFLD influences the development of insulin resistance within the periphery, and gut-related factors impact on the development of MAFLD. We also discuss lifestyle strategies for optimising metabolic liver health.

Roles of bile acids signaling in neuromodulation under physiological and pathological conditions

Bile acids (BA) are important physiological molecules not only mediating nutrients absorption and metabolism in peripheral tissues, but exerting neuromodulation effect in the central nerve system (CNS). The catabolism of cholesterol to BA occurs predominantly in the liver by the classical and alternative pathways, or in the brain initiated by the neuronal-specific enzyme CYP46A1 mediated pathway. Circulating BA could cross the blood brain barrier (BBB) and reach the CNS through passive diffusion or BA transporters. Brain BA might trigger direct signal through activating membrane and nucleus receptors or affecting activation of neurotransmitter receptors. Peripheral BA may also provide the indirect signal to the CNS via farnesoid X receptor (FXR) dependent fibroblast growth factor 15/19 (FGF15/19) pathway or takeda G protein coupled receptor 5 (TGR5) dependent glucagon-like peptide-1 (GLP-1) pathway. Under pathological conditions, alterations in BA metabolites have been discovered as potential pathogenic contributors in multiple neurological disorders. Attractively, hydrophilic ursodeoxycholic acid (UDCA), especially tauroursodeoxycholic acid (TUDCA) can exert neuroprotective roles by attenuating neuroinflammation, apoptosis, oxidative or endoplasmic reticulum stress, which provides promising therapeutic effects for treatment of neurological diseases. This review summarizes recent findings highlighting the metabolism, crosstalk between brain and periphery, and neurological functions of BA to elucidate the important role of BA signaling in the brain under both physiological and pathological conditions.

Ganoderma lucidum polysaccharides improve lipid metabolism against high-fat diet-induced dyslipidemia

ETHNOPHARMACOLOGICAL RELEVANCE

As a kind of traditional medicinal fungi, Ganoderma lucidum has been employed as folk medicine in China against multiple metabolic diseases on account of its superior bioactivities. Recently, accumulated reports have investigated the protective effects of G. lucidum polysaccharides (GLP) on ameliorating dyslipidemia. However, the specific mechanism by which GLP improves dyslipidemia is not completely clear.

AIMS OF THE STUDY

This study aimed to investigate the protective effects of GLP on high-fatdiet-induced hyperlipidemia and exploring its underlying mechanism.

MATERIALS AND METHODS

The GLP was successfully obtained from G. lucidum mycelium. The mice were conducted with high-fatdiet to establish the hyperlipidemia model. Biochemical determination, histological analysis, immunofluorescence, western blot and real-time qPCR were used to assess the alterations in high-fatdiet-treated mice after the GLP intervention.

RESULTS

It was found that GLP administration significantly decreased body weight gain and the excessive lipid levels, and partly alleviated tissue injury. Oxidative stress and inflammations were efficiently ameliorated after the treatment of GLP by activing Nrf2-Keap1 and inhibiting NF-κB signal pathways. GLP promoted cholesterol reverse transport by LXRα-ABCA1/ABCG1 signaling, increased the expressions of CYP7A1 and CYP27A1 responsible for bile acids production, accompanied by inhibition of intestinal FXR-FGF15 levels. Besides, multiple target proteins involved in lipid metabolism were also significantly modulated under the intervention of GLP.

CONCLUSION

Taken together, our results suggested that GLP showed potential lipid-lowering effects and its possible mechanism was involved in improving oxidative stress and inflammation response, modulating bile acids synthesis and lipid regulatory factors, and promoting reverse cholesterol transport, thereby suggesting that GLP may possibly used as a dietary supplement or medication for the adjuvant therapy for hyperlipidemia.

Altered fecal microbiome and metabolome profiles in rat models of short bowel syndrome

Introduction

Short bowel syndrome (SBS) is featured by impaired nutrients and fluids absorption due to massive small intestine resection. Gut dysbiosis has been implicated in SBS, this study aimed to characterize the metagenomic and metabolomic profiles of SBS and identify potential therapeutic targets.

Methods

Fecal samples from SBS and Sham rats (n = 8 per group) were collected for high-throughput metagenomic sequencing. Fecal metabolomics was measured by untargeted liquid chromatography-mass spectrometry.

Results

We found that the species-level α-diversity significantly decreased in SBS rats, accompanied by altered microbiome compositions. The beneficial anaerobes from Firmicutes and Bacteroidetes were depleted while microorganisms from Lactobacillus, Escherichia, Enterococcus, and Streptococcus were enriched in faces from SBS rats. LEfSe analysis identified 17 microbial species and 38 KEGG modules that were remarkably distinct between SBS and Sham rats. In total, 1,577 metabolites with known chemical identity were detected from all samples, among them, 276 metabolites were down-regulated and 224 metabolites were up-regulated in SBS group. The typical signatures of SBS fecal metabolome comprised reduced short-chain fatty acids and products of amino acid metabolism (indole derivatives and p-cresol), as well as altered bile acid spectrum. We revealed 215 robust associations between representative differentially abundant microbial species and metabolites, the species with the same changing trend tended to have a similar correlation with some certain metabolites.

Conclusion

The fecal microbiome and metabolome significantly altered in SBS. Our findings may lay the foundation for developing new strategies to facilitate intestinal adaptation in SBS patients.

Reshaping the gut microbiome and bile acid composition by Gyejibongnyeong-hwan ameliorates western diet-induced dyslipidemia

Gyejibongnyeong-hwan (GBH), a traditional Chinese medicine, is used in clinical practice to treat blood stasis in metabolic diseases. Herein, we examined the effects of GBH on dyslipidemia and investigated the underlying mechanisms by focusing on modulation of the gut microbiota-bile acid axis by GBH. We utilized a Western diet-induced dyslipidemia mouse model and divided animals into the following four groups (n = 5 each): the normal chow diet, vehicle control (WD), simvastatin (Sim, 10 mg/kg/day simvastatin; positive control), and GBH (GBH, 300 mg/kg/day) groups. The drugs were administered for 10 weeks, and morphological changes in the liver and aorta were analyzed. The mRNA expression of genes related to cholesterol metabolism, gut microbiota, and bile acid profiles were also evaluated. The GBH group showed significantly lower levels of total cholesterol, accumulation of lipids, and inflammatory markers in the liver and aorta of Western diet-fed mice. Low-density lipoprotein cholesterol levels were significantly lower in the GBH group than in the WD group (P < 0.001). The expression of cholesterol excretion-associated genes such as liver X receptor alpha and ATP-binding cassette subfamily G member 8, as well as the bile acid synthesis gene cholesterol 7 alpha-hydroxylase, which lowers cholesterol in circulation, was increased. Furthermore, GBH inhibited the intestinal farnesoid X receptor (FXR)-fibroblast growth factor 15 signaling pathway through the interactions of gut microbiota with bile acids acting as FXR ligands, which included chenodeoxycholic acid and lithocholic acid. Overall, GBH improved dyslipidemia induced by a Western diet by modulating the gut microbiota-bile acid axis.

Pathogenic mechanisms and regulatory factors involved in alcoholic liver disease

Alcoholism is a widespread and damaging behaviour of people throughout the world. Long-term alcohol consumption has resulted in alcoholic liver disease (ALD) being the leading cause of chronic liver disease. Many metabolic enzymes, including alcohol dehydrogenases such as ADH, CYP2E1, and CATacetaldehyde dehydrogenases ALDHsand nonoxidative metabolizing enzymes such as SULT, UGT, and FAEES, are involved in the metabolism of ethanol, the main component in alcoholic beverages. Ethanol consumption changes the functional or expression profiles of various regulatory factors, such as kinases, transcription factors, and microRNAs. Therefore, the underlying mechanisms of ALD are complex, involving inflammation, mitochondrial damage, endoplasmic reticulum stress, nitrification, and oxidative stress. Moreover, recent evidence has demonstrated that the gut-liver axis plays a critical role in ALD pathogenesis. For example, ethanol damages the intestinal barrier, resulting in the release of endotoxins and alterations in intestinal flora content and bile acid metabolism. However, ALD therapies show low effectiveness. Therefore, this review summarizes ethanol metabolism pathways and highly influential pathogenic mechanisms and regulatory factors involved in ALD pathology with the aim of new therapeutic insights.

Yinchen decoction protects against cholic acid diet-induced cholestatic liver injury in mice through liver and ileal FXR signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Cholestasis is a pathophysiological syndrome characterized by the accumulation of bile acids (BAs) that leads to severe liver disease. Artemisia capillaris is documented in Chinese Pharmacopoeia as the authentic resources for Yinchen. Although Yinchen (Artemisia capillaris Thunb.) decoction (YCD) has been used in China for thousands of years to treat jaundice, the underlying mechanisms to ameliorate cholestatic liver injury have not been elucidated.

AIM OF THE STUDY

To investigate the molecular mechanism of how YCD protects against 1% cholic acid (CA) diet-induced intrahepatic cholestasis through FXR signaling.

MATERIALS AND METHODS

Wild-type and Fxr-deficient mice were fed a diet containing 1% CA to establish the intrahepatic cholestasis model. The mice received low-, medium-, or high-dose YCD for 10 days. Plasma biochemical markers were analyzed, liver injury was identified by histopathology, and hepatic and plasma BA content was analyzed. Western blot was used to determine the expression levels of transporters and enzymes involved in BA homeostasis in the liver and intestine.

RESULTS

In wild-type mice, YCD significantly improved plasma transaminase levels, multifocal hepatocellular necrosis, and hepatic and plasma BA contents, upregulated the expression of hepatic FXR and downstream target enzymes and transporters. Meanwhile, YCD significantly induced the expressions of intestinal FXR and FGF15 and hepatic FGFR4. In contrast, the hepatic protective effect of YCD on cholestasis was abolished in Fxr-deficient mice.

CONCLUSION

YCD protects against cholestatic liver injury induced by a CA diet by restoring the homeostasis of BAs via activation of the liver FXR/SHP and ileal FXR/FGF15 signaling pathways. Furthermore, chlorogenic acid and caffeic acid may be the pharmacological agents in YCD responsible for protecting against cholestatic liver injury.

Connecting the Gut Microbiota and Neurodegenerative Diseases: the Role of Bile Acids

With the acceleration of global population aging, neurodegenerative diseases (NDs) will become the second leading cause of death in the world, which seriously threatens human life and health. Alzheimer's disease and Parkinson's disease are the most common and typical NDs. The exact mechanisms of the NDs occurrence and development remain unclear, which may be related to immune, oxidative stress, and abnormal aggregation of pathogenic proteins. Studies have suggested that gut microbiota (GM) influences brain function and plays an important role in regulating emotional and cognitive function. Recently, bile acids (BAs) have become the "star molecule" in the microbiota-gut-brain (MGB) axis research. BAs have been reported to exert anti-inflammatory, antioxidant, and neuroprotective activities in NDs. However, the role of BAs in the connection between GM and the central nervous system (CNS) is still unclear. In this review, we will review the possible mechanisms of BAs between GM and NDs and explore the function of BAs to provide ideas for the prevention and treatment of NDs in the future.