Raspberry Ketone Attenuates Hepatic Fibrogenesis and Inflammation via Regulating the Crosstalk of FXR and PGC-1α Signaling.

Hepatic fibrosis is a compensatory response to chronic liver injury and inflammation, and dietary intervention is recommended as one of the fundamental prevention strategies. Raspberry ketone (RK) is an aromatic compound first isolated from raspberry and widely used to prepare food flavors. The current study investigated the hepatoprotection and potential mechanism of RK against hepatic fibrosis. In vitro, hepatic stellate cell (HSC) activation was stimulated with TGF-ß and cultured with RK, farnesoid X receptor (FXR), or peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) agonist or inhibitor, respectively. In vivo, C57BL/6 mice were injected intraperitoneally with thioacetamide (TAA) at 100/200 mg/kg from the first to the fifth week. Mice were intragastrically administrated with RK or Cur once a day from the second to the fifth week. In activated HSCs, RK inhibited extracellular matrix (ECM) accumulation, inflammation, and epithelial-mesenchymal transition (EMT) process. RK both activated FXR/PGC-1α and regulated their crosstalk, which were verified by their inhibitors and agonists. Deficiency of FXR or PGC-1α also attenuated the effect of RK on the reverse of activated HSCs. RK also decreased serum ALT/AST levels, liver histopathological change, ECM accumulation, inflammation, and EMT in mice caused by TAA. Double activation of FXR/PGC-1α might be the key targets for RK against hepatic fibrosis. Above all, these discoveries supported the potential of RK as a novel candidate for the dietary intervention of hepatic fibrosis.

Local complement activation and modulation in mucosal immunity.

The complement system is an evolutionarily conserved arm of innate immunity, which forms one of the first lines of host response to pathogens and assists in the clearance of debris. A deficiency in key activators/amplifiers of the cascade results in recurrent infection, whereas a deficiency in regulating the cascade predisposes to accelerated organ failure, as observed in colitis and transplant rejection. Given that there are over 60 proteins in this system, it has become an attractive target for immunotherapeutics, many of which are United States Food and Drug Administration-approved or in multiple phase 2/3 clinical trials. Moreover, there have been key advances in the last few years in the understanding of how the complement system operates locally in tissues, independent of its activities in circulation. In this review, we will put into perspective the abovementioned discoveries to optimally modulate the spatiotemporal nature of complement activation and regulation at mucosal surfaces.

Lactobacillus rhamnosus GG ameliorates triptolide-induced liver injury through modulation of the bile acid-FXR axis.

Triptolide (TP) is the principal bioactive compound of Tripterygium wilfordii with significant anti-tumor, anti-inflammatory and immunosuppressive activities. However, its severe hepatotoxicity greatly limits its clinical use. The underlying mechanism of TP-induced liver damage is still poorly understood. Here, we estimate the role of the gut microbiota in TP hepatotoxicity and investigate the bile acid metabolism mechanisms involved. The results of the antibiotic cocktail (ABX) and fecal microbiota transplantation (FMT) experiment demonstrate the involvement of intestinal flora in TP hepatotoxicity. Moreover, TP treatment significantly perturbed gut microbial composition and reduced the relative abundances of Lactobacillus rhamnosus GG (LGG). Supplementation with LGG reversed TP-induced hepatotoxicity by increasing bile salt hydrolase (BSH) activity and reducing the increased conjugated bile acids (BA). LGG supplementation upregulates hepatic FXR expression and inhibits NLRP3 inflammasome activation in TP-treated mice. In summary, this study found that gut microbiota is involved in TP hepatotoxicity. LGG supplementation protects mice against TP-induced liver damage. The underlying mechanism was associated with the gut microbiota-BA-FXR axis. Therefore, LGG holds the potential to prevent and treat TP hepatotoxicity in the clinic.

Microbiota metabolized Bile Acids accelerate Gastroesophageal Adenocarcinoma via FXR inhibition.

Background: The incidence of Barrett esophagus (BE) and Gastroesophageal Adenocarcinoma (GEAC) correlates with obesity and a diet rich in fat. Bile acids (BA) support fat digestion and undergo microbial metabolization in the gut. The farnesoid X receptor (FXR) is an important modulator of the BA homeostasis. The capacity of inhibiting cancer-related processes when activated, make FXR an appealing therapeutic target. In this work, we assess the role of diet on the microbiota-BA axis and evaluate the role of FXR in disease progression. Results: Here we show that high fat diet (HFD) accelerated tumorigenesis in L2-IL1B mice (BE- and GEAC- mouse model) while increasing BA levels and enriching gut microbiota that convert primary to secondary BA. While upregulated in BE, expression of FXR was downregulated in GEAC in mice and humans. In L2-IL1B mice, FXR knockout enhanced the dysplastic phenotype and increased Lgr5 progenitor cell numbers. Treatment of murine organoids and L2-IL1B mice with the FXR agonist obeticholic acid (OCA) deacelerated GEAC progression. Conclusion: We provide a novel concept of GEAC carcinogenesis being accelerated via the diet-microbiome-metabolome axis and FXR inhibition on progenitor cells. Further, FXR activation protected with OCA ameliorated the phenotype in vitro and in vivo, suggesting that FXR agonists have potential as differentiation therapy in GEAC prevention.

The renal apical sodium-dependent bile acid transporter expression rescue attenuates renal damage in diabetic nephropathy via farnesoid X receptor activation.

AIM: Bile acids (BA) function as signalling molecules regulating glucose-lipid homeostasis and energy expenditure. However, the expression of the apical sodium-dependent bile acid transporter (ASBT) in the kidney, responsible for renal BA reabsorption, is downregulated in patients with diabetic kidney disease (DKD). Using the db/db mouse model of DKD, this study aimed to investigate the effects of rescuing ASBT expression via adeno-associated virus-mediated delivery of ASBT (AAVASBT) on kidney protection. METHODS: Six-week-old male db/db mice received an intraparenchymal injection of AAVASBT at a dose of 1 × 1011 viral genomes (vg)/animal and were subsequently fed a chow diet for 2 weeks. Male db/m mice served as controls. For drug treatment, daily intraperitoneal (i.p.) injections of the farnesoid X receptor (FXR) antagonist guggulsterone (GS, 10 mg/kg) were administered one day after initiating the experiment. RESULTS: AAVASBT treatment rescued renal ASBT expression and reduced the urinary BA output in db/db mice. AAVASBT treatment activated kidney mitochondrial biogenesis and ameliorated renal impairment associated with diabetes by activating FXR. In addition, the injection of FXR antagonist GS in DKD mice would reverse these beneficial effects by AAVASBT treatment. CONCLUSION: Our work indicated that restoring renal ASBT expression slowed the course of DKD via activating FXR. FXR activation stimulates mitochondrial biogenesis while reducing renal oxidative stress and lipid build up, indicating FXR activation's crucial role in preventing DKD. These findings further suggest that the maintenance of renal BA reabsorption could be a viable treatment for DKD.

Ursodeoxycholic Acid Modulates the Interaction of miR-21 and Farnesoid X Receptor and NF-κB Signaling.

(1) Background: This study investigates the effects of Ursodeoxycholic acid (UDCA) on NF-κB signaling, farnesoid X receptor (FXR) singling, and microRNA-21 in HepG2 cells. (2) Methods: HepG2 cells were treated with lipopolysaccharide (LPS) to simulate hepatic inflammation. The investigation focused on the expression of NF-κB activation, which was analyzed using Western blot, confocal microscopy, and Electrophoretic Mobility-shift Assays (EMSA). Additionally, NF-κB and farnesoid X receptor (FXR) singling expressions of micro-RNA-21, COX-2, TNF-α, IL-6, cyp7A1, and shp were assessed by RT-PCR. (3) Results: UDCA effectively downregulated LPS-induced expressions of NF-κB/65, p65 phosphorylation, and also downregulated FXR activity by Western blot. Confocal microscopy and EMSA results confirmed UDCA's role in modulating NF-κB signaling. UDCA reduced the expressions of LPS-induced COX-2, TNF-α, and IL-6, which were related to NF-κB signaling. UDCA downregulated LPS-induced cyp7A1 gene expression and upregulated shp gene expression, demonstrating selective gene regulation via FXR. UDCA also significantly decreased micro-RNA 21 levels. (4) Conclusions: This study demonstrates UDCA's potent anti-inflammatory effects on NF-κB and FXR signaling pathways, and thus its potential to modulate hepatic inflammation and carcinogenesis through interactions with NF-κB and FXR. The decrease in micro-RNA 21 expression further underscores its therapeutic potential.

Jingangteng capsules ameliorate liver lipid disorders in diabetic rats by regulating microflora imbalances, metabolic disorders, and farnesoid X receptor.

BACKGROUND: The plant Smilax china L., also known as Jingangteng, is suspected of regulating glucose and lipid metabolism. Jingangteng capsules (JGTCs) are commonly used to treat gynecological inflammation in clinical practice. However, it is not clear whether JGTCs can regulate glucose and lipid metabolism, and the mechanism is unclear. PURPOSE: To investigate the impact and mechanism of action of JGTCs on diabetes and liver lipid disorders in rats. METHODS: The chemical constituents of JGTCs were examined using ultra-high-performance liquid chromatography with quadrupole time-of-flight mass spectrometry. A high-fat diet and streptozotocin-induced diabetes model was used to evaluate anti-diabetic effects by assessing blood glucose and lipid levels and liver function. The mechanism was explored using fecal 16S rRNA gene sequencing and metabolomics profiling, reverse transcription-quantiative polymerase chain reaction (RT-qPCR), and Western blot analysis. RESULTS: Thirty-three components were identified in JGTCs. The serological and histomorphological assays revealed that JGTC treatment reduced levels of blood glucose and lipids, aspartate aminotransferase, alanine aminotransferase, and lipid accumulation in the liver of diabetic rats. According to 16S rDNA sequencing, JGTCs improved species richness and diversity in diabetic rats' intestinal flora and restored 22 dysregulated bacteria to control levels. Fecal metabolomics analysis showed that the altered fecal metabolites were rich in metabolites, such as histidine, taurine, low taurine, tryptophan, glycerophospholipid, and arginine. Serum metabolomics analysis indicated that serum metabolites were enriched in the metabolism of glycerophospholipids, fructose and mannose, galactose, linoleic acid, sphingolipids, histidine, valine, leucine and isoleucine biosynthesis, and tryptophan metabolism. Heatmaps revealed a strong correlation between metabolic parameters and gut microbial phylotypes. Molecular biology assays showed that JGTC treatment reversed the decreased expression of farnesoid X receptor (FXR) in the liver of diabetic rats and inhibited the expression of lipogenic genes (Srebp1c and FAS) as well as inflammation-related genes (interleukin (IL)-ß, tumor necrosis factor (TNF)-α, and IL-6). Liver metabolomics analysis indicated that JGTC could significantly regulate a significant number of bile acid metabolites associated with FXR, such as glyco-beta-muricholic acid, glycocholic acid, tauro-beta-muricholic acid, and tauro-gamma-muricholic acid. CONCLUSIONS: This was the first study to investigate the mechanisms of JGTCs' effects on liver lipid disorders in diabetic rats. JGTCs inhibited liver lipid accumulation and inflammatory responses in diabetic rats by affecting intestinal flora and metabolic disorders and regulating FXR-fat synthesis-related pathways to alleviate diabetic lipid disorders.

Diallyl disulfide, the bioactive component of Allium species, ameliorates pulmonary fibrosis by mediating the crosstalk of farnesoid X receptor and yes-associated protein 1 signaling pathway.

Environmental pollution, virus infection, allergens, and other factors may cause respiratory disease, which could be improved by dietary therapy. Allium species are common daily food seasoning and have high nutritional and medical value. Diallyl disulfide (DADS) is the major volatile oil compound of Allium species. The present study aims to explore the preventive effect and potential mechanism of DADS on pulmonary fibrosis. C57BL/6J mice were intratracheally injected with bleomycin (BLM) to establish pulmonary fibrosis and then administrated with DADS. Primary lung fibroblasts or A549 were stimulated with BLM, followed by DADS, farnesoid X receptor (FXR) agonist (GW4064), yes-associated protein 1 (YAP1) inhibitor (verteporfin), or silencing of FXR and YAP1. In BLM-stimulated mice, DADS significantly ameliorated histopathological changes and interleukin-1ß levels in bronchoalveolar lavage fluid. DADS decreased fibrosis markers, HIF-1α, inflammatory cytokines, and epithelial-mesenchymal transition in pulmonary mice and activated fibroblasts. DADS significantly enhanced FXR expression and inhibited YAP1 activation, which functions as GW4064 and verteporfin. A deficiency of FXR or YAP1 could result in the increase of these two protein expressions, respectively. DADS ameliorated extracellular matrix deposition, hypoxia, epithelial-mesenchymal transition, and inflammation in FXR or YAP1 knockdown A549. Taken together, targeting the crosstalk of FXR and YAP1 might be the potential mechanism for DADS against pulmonary fibrosis. DADS can serve as a potential candidate or dietary nutraceutical supplement for the treatment of pulmonary fibrosis.

Glycodeoxycholic acid inhibits primary bile acid synthesis with minor effects on glucose- and lipid homeostasis in humans.

BACKGROUND: Bile acids play vital roles in control of lipid-, glucose-, and energy metabolism by activating Takeda G protein-coupled receptor 5 (TGR5) and Farnesoid X receptor (FXR), the latter promoting production of the endocrine-acting fibroblast growth factor 19 (FGF19). Short-term administration of single bile acids has been reported to enhance plasma levels of GLP-1 and to enhance energy expenditure. However, prolonged bile acid supplementation, e.g. of chenodeoxycholic acid (CDCA) for gallstone dissolution, has been reported to have adverse effects. STUDY DESIGN: In this proof-of-concept study, we assessed the safety and metabolic effects of oral glycine-conjugated deoxycholic acid (GDCA) administration at 10 mg/kg/day using regular and slow-release capsules (mimicking physiological bile acid release) over 30 days in two groups of each 10 healthy lean men respectively. MAIN FINDINGS: GDCA increased postprandial total bile acid and FGF19 concentrations while suppressing those of the primary bile acids CDCA and cholic acid. Plasma levels of 7α-hydroxy-4-cholesten-3-one were reduced, indicating repressed hepatic bile acid synthesis. There were minimal effects on indices of lipid-, glucose-, and energy metabolism. No serious adverse events were reported during GDCA administration in either capsule types, although 50% of participants showed mild increases in plasma levels of liver transaminases and 80% (regular capsules) and 50% (slow-release capsules) of participants experienced gastrointestinal adverse events. CONCLUSION: GDCA administration leads to elevated FGF19 levels and effectively inhibits primary bile acid synthesis, supporting therapy compliance and its effectiveness. However, effects on lipid, glucose- and energy metabolism were minimal, indicating that expanding the pool of this relatively hydrophobic bile acid does not impact energy metabolism in healthy subjects.

Silibinin, a commonly used therapeutic agent for non-alcohol fatty liver disease, functions through upregulating intestinal expression of fibroblast growth factor 15/19.

BACKGROUND AND PURPOSE: Silibinin is used to treat non-alcohol fatty liver disease (NAFLD) despite having rapid liver metabolism. Therefore, we investigated the role of the intestine in silibinin mechanism of action. EXPERIMENTAL APPROACH: NAFLD mice model was established by feeding them with a high-fat diet (HFD). Liver pathological were examined using H&E and oil red O staining. Tissue distribution of silibinin was detected by LC-MS/MS. SiRNA was employed for gene silencing and plasmid was used for gene overexpression. ChIP-qPCR assay was performed to detect the levels of histone acetylation. Recombinant adeno-associated virus 9-short hairpin-fibroblast growth factor (FGF)-15 and -farnesoid X receptor (FXR; NR1H4) were used to knockdown expression of FGF-15 and FXR. KEY RESULTS: Oral silibinin significantly reversed NAFLD in mice, although liver concentration was insufficient for reduction of lipid accumulation in hepatocytes. Among endogenous factors capable of reversing NAFLD, the expression of Fgf-15 was selectively up-regulated by silibinin in ileum and colon of mice. When intestinal expression of Fgf-15 was knocked down, protection of silibinin against lipid accumulation and injury of livers nearly disappeared. Silibinin could reduce activity of histone deacetylase 2 (HDAC2), enhance histone acetylation in the promoter region of FXR and consequently increase intestinal expression of FGF-15/19. CONCLUSION AND IMPLICATIONS: Oral silibinin selectively promotes expression of FGF-15/19 in ileum by enhancing transcription of FXR via reduction of HDAC2 activity, and FGF-15/19 enters into circulation to exert anti-NAFLD action. As the site of action is the intestine this would explain the discrepancy between pharmacodynamics and pharmacokinetics of silibinin.

Obeticholic Acid Inhibit Mitochondria Dysfunction Via Regulating ERK1/2-DRP Pathway to Exert Protective Effect on Lipopolysaccharide-Induced Myocardial Injury.

Farnesoid X receptor (FXR) plays critical regulatory roles in cardiovascular physiology/pathology. However, the role of FXR agonist obeticholic acid (OCA) in sepsis-associated myocardial injury and underlying mechanisms remain unclear. C57BL/6J mice are treated with OCA before lipopolysaccharide (LPS) administration. The histopathology of the heart and assessment of FXR expression and mitochondria function are performed. To explore the underlying mechanisms, H9c2 cells, and primary cardiomyocytes are pre-treated with OCA before LPS treatment, and extracellular signal-regulated protein kinase (ERK) inhibitor PD98059 is used. LPS-induced myocardial injury in mice is significantly improved by OCA pretreatment. Mechanistically, OCA pretreatment decreased reactive oxygen species (ROS) levels and blocked the loss of mitochondrial membrane potential (ΔΨm) in cardiomyocytes. The expression of glutathione peroxidase 1 (GPX1), superoxide dismutase 1 (SOD1), superoxide dismutase 2 (SOD2), and nuclear factor erythroid 2-related factor 2 (NRF-2) increased in the case of OCA pretreatment. In addition, OCA improved mitochondria respiratory chain with increasing Complex I expression and decreasing cytochrome C (Cyt-C) diffusion. Moreover, OCA pretreatment inhibited LPS-induced mitochondria dysfunction via suppressing ERK1/2-DRP signaling pathway. FXR agonist OCA inhibits LPS-induced mitochondria dysfunction via suppressing ERK1/2-DRP signaling pathway to protect mice against LPS-induced myocardial injury.

Obeticholic acid attenuates the intestinal barrier disruption in a rat model of short bowel syndrome.

BACKGROUND: Short bowel syndrome (SBS) features nutrients malabsorption and impaired intestinal barrier. Patients with SBS are prone to sepsis, intestinal flora dysbiosis and intestinal failure associated liver disease. Protecting intestinal barrier and preventing complications are potential strategies for SBS treatment. This study aims to investigate the effects of farnesoid X receptor (FXR) agonist, obeticholic acid (OCA), have on intestinal barrier and ecological environment in SBS. METHODS AND RESULTS: Through testing the small intestine and serum samples of patients with SBS, impaired intestinal barrier was verified, as evidenced by reduced expressions of intestinal tight junction proteins (TJPs), increased levels of apoptosis and epithelial cell damage. The intestinal expressions of FXR and related downstream molecules were decreased in SBS patients. Then, global FXR activator OCA was used to further dissect the potential role of the FXR in a rat model of SBS. Low expressions of FXR-related molecules were observed on the small intestine of SBS rats, along with increased proinflammatory factors and damaged barrier function. Furthermore, SBS rats possessed significantly decreased body weight and elevated death rate. Supplementation with OCA mitigated the damaged intestinal barrier and increased proinflammatory factors in SBS rats, accompanied by activated FXR-related molecules. Using 16S rDNA sequencing, the regulatory role of OCA on gut microbiota in SBS rats was witnessed. LPS stimulation to Caco-2 cells induced apoptosis and overexpression of proinflammatory factors in vitro. OCA incubation of LPS-pretreated Caco-2 cells activated FXR-related molecules, increased the expressions of TJPs, ameliorated apoptosis and inhibited overexpression of proinflammatory factors. CONCLUSIONS: OCA supplementation could effectively ameliorate the intestinal barrier disruption and inhibit overexpression of proinflammatory factors in a rat model of SBS and LPS-pretreated Caco-2 cells. As a selective activator of FXR, OCA might realize its protective function through FXR activation.

Bile acids and coronavirus disease 2019.

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been significantly alleviated. However, long-term health effects and prevention strategy remain unresolved. Thus, it is essential to explore the pathophysiological mechanisms and intervention for SARS-CoV-2 infection. Emerging research indicates a link between COVID-19 and bile acids, traditionally known for facilitating dietary fat absorption. The bile acid ursodeoxycholic acid potentially protects against SARS-CoV-2 infection by inhibiting the farnesoid X receptor, a bile acid nuclear receptor. The activation of G-protein-coupled bile acid receptor, another membrane receptor for bile acids, has also been found to regulate the expression of angiotensin-converting enzyme 2, the receptor through which the virus enters human cells. Here, we review the latest basic and clinical evidence linking bile acids to SARS-CoV-2, and reveal their complicated pathophysiological mechanisms.

A combined nanotherapeutic approach targeting farnesoid X receptor, ferroptosis, and fibrosis for nonalcoholic steatohepatitis treatment.

Obeticholic acid (OCA), a farnesoid X receptor (FXR) agonist with favorable effects on fatty and glucose metabolism, has been considered the leading candidate drug for nonalcoholic steatohepatitis (NASH) treatment. However, its limited effectiveness in resolving liver fibrosis and lipotoxicity-induced cell death remains a major drawback. Ferroptosis, a newly recognized form of cell death characterized by uncontrolled lipid peroxidation, is involved in the progression of NASH. Nitric oxide (NO) is a versatile biological molecule that can degrade extracellular matrix. In this study, we developed a PEGylated thiolated hollow mesoporous silica nanoparticles (MSN) loaded with OCA, as well as a ferroptosis inhibitor liproxsatin-1 and a NO donor S-nitrosothiol (ONL@MSN). Biochemical analyses, histology, multiplexed flow cytometry, bulk-tissue RNA sequencing, and fecal 16S ribosomal RNA sequencing were utilized to evaluate the effects of the combined nanoparticle (ONL@MSN) in a mouse NASH model. Compared with the OCA-loaded nanoparticles (O@MSN), ONL@MSN not only protected against hepatic steatosis but also greatly ameliorated fibrosis and ferroptosis. ONL@MSN also displayed enhanced therapeutic actions on the maintenance of intrahepatic macrophages/monocytes homeostasis, inhibition of immune response/lipid peroxidation, and correction of microbiota dysbiosis. These findings present a promising synergistic nanotherapeutic strategy for the treatment of NASH by simultaneously targeting FXR, ferroptosis, and fibrosis.

Tailoring FXR Modulators for Intestinal Specificity: Recent Progress and Insights.

While FXR has shown promise in regulating bile acid synthesis and maintaining glucose and lipid homeostasis, undesired side effects have been observed in clinical trials. To address this issue, the development of intestinally restricted FXR modulators has gained attention as a new avenue for drug design with the potential for safer systematic effects. Our review examines all currently known intestinally restricted FXR ligands and provides insights into the steps taken to enhance intestinal selectivity.

Functional metabolomics characterizes the contribution of farnesoid X receptor in pyrrolizidine alkaloid-induced hepatic sinusoidal obstruction syndrome.

Consumption of herbal products containing pyrrolizidine alkaloids (PAs) is one of the major causes for hepatic sinusoidal obstruction syndrome (HSOS), a deadly liver disease. However, the crucial metabolic variation and biomarkers which can reflect these changes remain amphibious and thus to result in a lack of effective prevention, diagnosis and treatments against this disease. The aim of the study was to determine the impact of HSOS caused by PA exposure, and to translate metabolomics-derived biomarkers to the mechanism. In present study, cholic acid species (namely, cholic acid, taurine conjugated-cholic acid, and glycine conjugated-cholic acid) were identified as the candidate biomarkers (area under the ROC curve 0.968 [95% CI 0.908-0.994], sensitivity 83.87%, specificity 96.55%) for PA-HSOS using two independent cohorts of patients with PA-HSOS. The increased primary bile acid biosynthesis and decreased liver expression of farnesoid X receptor (FXR, which is known to inhibit bile acid biosynthesis in hepatocytes) were highlighted in PA-HSOS patients. Furtherly, a murine PA-HSOS model induced by senecionine (50 mg/kg, p.o.), a hepatotoxic PA, showed increased biosynthesis of cholic acid species via inhibition of hepatic FXR-SHP singling and treatment with the FXR agonist obeticholic acid restored the cholic acid species to the normal levels and protected mice from senecionine-induced HSOS. This work elucidates that increased levels of cholic acid species can serve as diagnostic biomarkers in PA-HSOS and targeting FXR may represent a therapeutic strategy for treating PA-HSOS in clinics.

Loss of the DNA-binding domain of the farnesoid X receptor gene causes severe liver and kidney injuries.

Farnesoid X receptor (FXR) regulates bile acid synthesis, lipid metabolism, and glucose homeostasis in metabolic organs. FXR-knockout (FXR-KO) mice lacking the last exon of the FXR gene develop normally and display no prenatal and early postnatal lethality, whereas human patients with mutations in the DNA-binding domain of the FXR gene develop severe hepatic dysfunction. In this study, we generated novel FXR-KO mice lacking the DNA-binding domain of the FXR gene using CRISPR-Cas9 technology and evaluated their phenotypes. Similar to the aforementioned FXR-KO mice, our novel mice showed elevated serum levels of total bile acids and total cholesterol. However, they were obviously short-lived, showing severe liver and renal pathologies at an early age. These results indicate that FXR, including its unknown isoforms, has more significant functions in multiple organs than previously reported. Thus, the novel FXR-KO mice could lead to a new aspect that requires reworking of previous knowledge of FXR in the liver and renal function.

Genipin improves obesity through promoting bile secretion and changing bile acids composition in diet-induced obese rats.

OBJECTIVES: Bile acids (BAs), as signaling molecules to regulate metabolism, have received considerable attention. Genipin is an iridoid compound extracted from Fructus Gradeniae, which has been shown to relieve adiposity and metabolic syndrome. Here, we investigated the mechanism of genipin counteracting obesity and its relationship with BAs signals in diet-induced obese (DIO) rats. METHODS: The DIO rats were received intraperitoneal injections of genipin for 10 days. The body weight, visceral fat, lipid metabolism in the liver, thermogenic genes expressions in brown fat, BAs metabolism and signals, and key enzymes for BAs synthesis were determined. KEY FINDINGS: Genipin inhibited fat synthesis and promoted lipolysis in the liver, and upregulated thermogenic gene expressions in brown adipose tissue of DIO rats. Genipin increased bile flow rate and upregulated the expressions of aquaporin 8 and the transporters of BAs in liver. Furthermore, genipin changed BAs composition by promoting alternative pathways and inhibiting classical pathways for BAs synthesis and upregulated the expressions of bile acid receptors synchronously. CONCLUSIONS: These results suggest that genipin ameliorate obesity through BAs-mediated signaling pathways.

Puerarin Modulates Hepatic Farnesoid X Receptor and Gut Microbiota in High-Fat Diet-Induced Obese Mice.

Obesity is associated with alterations in lipid metabolism and gut microbiota dysbiosis. This study investigated the effects of puerarin, a bioactive isoflavone, on lipid metabolism disorders and gut microbiota in high-fat diet (HFD)-induced obese mice. Supplementation with puerarin reduced plasma alanine aminotransferase, liver triglyceride, liver free fatty acid (FFA), and improved gut microbiota dysbiosis in obese mice. Puerarin's beneficial metabolic effects were attenuated when farnesoid X receptor (FXR) was antagonized, suggesting FXR-mediated mechanisms. In hepatocytes, puerarin ameliorated high FFA-induced sterol regulatory element-binding protein (SREBP) 1 signaling, inflammation, and mitochondrial dysfunction in an FXR-dependent manner. In obese mice, puerarin reduced liver damage, regulated hepatic lipogenesis, decreased inflammation, improved mitochondrial function, and modulated mitophagy and ubiquitin-proteasome pathways, but was less effective in FXR knockout mice. Puerarin upregulated hepatic expression of FXR, bile salt export pump (BSEP), and downregulated cytochrome P450 7A1 (CYP7A1) and sodium taurocholate transporter (NTCP), indicating modulation of bile acid synthesis and transport. Puerarin also restored gut microbial diversity, the Firmicutes/Bacteroidetes ratio, and the abundance of Clostridium celatum and Akkermansia muciniphila. This study demonstrates that puerarin effectively ameliorates metabolic disturbances and gut microbiota dysbiosis in obese mice, predominantly through FXR-dependent pathways. These findings underscore puerarin's potential as a therapeutic agent for managing obesity and enhancing gut health, highlighting its dual role in improving metabolic functions and modulating microbial communities.

Bile acid metabolism in health and ageing-related diseases.

Bile acids (BAs) have surpassed their traditional roles as lipid solubilizers and regulators of BA homeostasis to emerge as important signalling molecules. Recent research has revealed a connection between microbial dysbiosis and metabolism disruption of BAs, which in turn impacts ageing-related diseases. The human BAs pool is primarily composed of primary BAs and their conjugates, with a smaller proportion consisting of secondary BAs. These different BAs exert complex effects on health and ageing-related diseases through several key nuclear receptors, such as farnesoid X receptor and Takeda G protein-coupled receptor 5. However, the underlying molecular mechanisms of these effects are still debated. Therefore, the modulation of signalling pathways by regulating synthesis and composition of BAs represents an interesting and novel direction for potential therapies of ageing-related diseases. This review provides an overview of synthesis and transportion of BAs in the healthy body, emphasizing its dependence on microbial community metabolic capacity. Additionally, the review also explores how ageing and ageing-related diseases affect metabolism and composition of BAs. Understanding BA metabolism network and the impact of their nuclear receptors, such as farnesoid X receptor and G protein-coupled receptor 5 agonists, paves the way for developing therapeutic agents for targeting BA metabolism in various ageing-related diseases, such as metabolic disorder, hepatic injury, cardiovascular disease, renal damage and neurodegenerative disease.