Bile Acid Receptor Research Articles

The potential mechanism of action of gut flora and bile acids through the TGR5/TRPV1 signaling pathway in diabetic peripheral neuropathic pain

Diabetic peripheral neuropathic pain (DPNP) is a major complication of diabetes that markedly affects the quality of life and health status of patients. Recent studies have investigated the potential regulatory influence of gut flora and bile acids on DPNP via the TGR5/TRPV1 signaling pathway. Dysbiosis of the gut flora not only directly affects bile acid metabolism but also significantly correlates with diabetes-associated neuropathy through interactions with the bile acid receptor TGR5 and the ion channel TRPV1. This review describes how alterations in the gut flora and bile acid metabolism contribute to the pathogenesis of DPNP through the TGR5/TRPV1 signaling pathway, revealing potential applications for this pathway in DPNP management. Furthermore, experimental and clinical studies have demonstrated the modulation of gut flora and bile acid metabolism as well as targeting the TGR5/TRPV1 signaling pathway as an innovative therapeutic approach. Further studies are warranted to elucidate the underlying mechanism and develop treatment modalities based on gut flora regulation and signaling pathway interventions, thus providing novel insights and approaches for DPNP therapy.

Metasilicate-based alkaline mineral water improves the growth performance of weaned piglets by maintaining gut-liver axis homeostasis through microbiota-mediated secondary bile acid pathway

Weaning stress causes substantial economic loss in the swine industry. Moreover, weaning-induced intestinal barrier damage and dysfunction of the gut-liver axis are associated with reduced growth performance in piglets. Metasilicate-based alkaline mineral water (AMW) has shown potential therapeutic effects on gastrointestinal disorders; however, the mechanisms involved and their overall effects on the gut-liver axis have not been explored. Here, sodium metasilicate (SMS) was used to prepare metasilicate-based AMW (basal water + 500 mg/L SMS). A total of 240 newly weaned piglets were allocated to the Control and SMS groups (6 replicate pens per group and 20 piglets per pen) for a 15-day trial period. Histopathological evaluations were conducted using hematoxylin and eosin staining. To analyze the composition of the gut microbiota, 16S rRNA PacBio SMRT Gene Full-Length Sequencing was performed. Western blotting and immunofluorescence were employed to assess protein expression levels. Our results indicated that metasilicate-based AMW effectively alleviated weaning-induced colonic or liver morphological injury and inflammatory response, as well as liver cholesterol metabolism disorders. Further analysis showed that metasilicate-based AMW promoted deoxycholic acid (DCA) biosynthesis by increasing the abundance of Lactobacillus_delbrueckii in the colon (P < 0.001). This consequently improved weaning-induced colon and liver injury and dysfunction through the DCA-secondary bile acid (SBA) receptors (SBAR)-nuclear factor-kappaB (NF-κB)/NOD-like receptor family pyrin domain-containing 3 (NLRP3) pathways. Growth performance parameters, including final body weight (P = 0.034) and average daily gain (P < 0.001), in the SMS group were significantly higher than those in the Control group. Therefore, metasilicate-based AMW maintains gut-liver axis homeostasis by regulating the microbiota-mediated SBA-SBAR pathway in piglets under weaning stress. Our research provides a new strategy for mitigating stress-induced gut-liver axis dysfunction in weaned piglets.

The Mechanism of Action of Bile Acid Receptor TGR5 in NAFLD

The Mechanism of Action of Bile Acid Receptor TGR5 in NAFLD

Activation of TGR5 in the injured nerve site according to a prevention protocol mitigates partial sciatic nerve ligation-induced neuropathic pain by alleviating neuroinflammation.

Neuropathic pain is a pervasive medical challenge currently lacking effective treatment options. Molecular changes at the site of peripheral nerve injury contribute to both peripheral and central sensitization, critical components of neuropathic pain. This study explores the role of the G-protein-coupled bile acid receptor (GPBAR1 or TGR5) in the peripheral mechanisms underlying neuropathic pain induced by partial sciatic nerve ligation in male mice. TGR5 was upregulated in the injured nerve site and predominantly colocalized with macrophages. Perisciatic nerve administration of the TGR5 agonist, INT-777 according to a prevention protocol (50 μg/μL daily from postoperative day [POD] 0 to POD6) provided sustained relief from mechanical allodynia and spontaneous pain, whereas the TGR5 antagonist, SBI-115 worsened neuropathic pain. Transcriptome sequencing linked the pain relief induced by TGR5 activation to reduced neuroinflammation, which was further evidenced by a decrease in myeloid cells and pro-inflammatory mediators (eg, CCL3, CXCL9, interleukin [IL]-6, and tumor necrosis factor [TNF] α) and an increase in CD86-CD206+ anti-inflammatory macrophages at POD7. Besides, myeloid-cell-specific TGR5 knockdown in the injured nerve site exacerbated both neuropathic pain and neuroinflammation, which was substantiated by bulk RNA-sequencing and upregulated expression levels of inflammatory mediators (including CCL3, CCL2, IL-6, TNF α, and IL-1β) and the increased number of monocytes/macrophages at POD7. Furthermore, the activation of microglia in the spinal cord on POD7 and POD14 was altered when TGR5 in the sciatic nerve was manipulated. Collectively, TGR5 activation in the injured nerve site mitigates neuropathic pain by reducing neuroinflammation, while TGR5 knockdown in myeloid cells worsens pain by enhancing neuroinflammation.

Novel Expression of Apical Bile Acid Transport (ASBT) More Proximally Than Distal Ileum Contributing to Enhanced Intestinal Bile Acid Absorption in Obesity.

Dietary lipid absorption is facilitated by bile acids. In the Zucker rat (ZR) model of obesity, bile acid absorption, mediated by the apical sodium bile acid transporter (ASBT), was increased in villus cells from the distal ileum. However, whether ASBT may be de novo expressed more proximally in the small intestine during obesity to facilitate additional bile acid absorption is not known. For this, starting from the end of the ileum to the mid jejunum, caudal-orally, five intestinal segments of equal length (S1-S5) were separated from lean and obese ZRs (LZR and OZR). Intestinal mucosa obtained from these segments were used for total RNA extraction, RT-qPCR and 3H-TCA uptake. The results showed that bile acid absorption along with the mRNA expression of ASBT and FXR progressively decreased caudal-orally in both LZRs and OZRs but was significantly higher in all small intestinal segments in OZRs. The expression of GATA4 was absent in the distal ileum (S1) in both LZRs and OZRs, but steadily increased along the proximal length in both. However, this steady increase was significantly reduced in the comparative obese proximal intestinal segments S2, S3, S4 and S5. The expressions of bile acid-activated G-protein-coupled bile acid receptor TGR5 and S1PR2 were unaltered in segments S1-S4 but were significantly increased in OZR S5. The paradigm changing observation of this study is that ASBT is expressed more proximally in the small intestine in obesity. This likely increases overall bile acid absorption and thereby lipid absorption in the proximal small intestine in obesity.

The development of hepatic steatosis depends on the presence of liver-innervating parasympathetic cholinergic neurons in mice fed a high-fat diet.

Hepatic lipid metabolism is regulated by the autonomic nervous system of the liver, with the sympathetic innervation being extensively studied, while the parasympathetic efferent innervation is less understood despite its potential importance. In this study, we investigate the consequences of disrupted brain-liver communication on hepatic lipid metabolism in mice exposed to obesogenic conditions. We found that a subset of hepatocytes and cholangiocytes are innervated by parasympathetic nerve terminals originating from the dorsal motor nucleus of the vagus. The elimination of the brain-liver axis by deleting parasympathetic cholinergic neurons innervating the liver prevents hepatic steatosis and promotes browning of inguinal white adipose tissue (ingWAT). The loss of liver-innervating cholinergic neurons increases hepatic Cyp7b1 expression and fasting serum bile acid levels. Furthermore, knockdown of the G protein-coupled bile acid receptor 1 gene in ingWAT reverses the beneficial effects of the loss of liver-innervating cholinergic neurons, leading to the reappearance of hepatic steatosis. Deleting liver-innervating cholinergic neurons has a small but significant effect on body weight, which is accompanied by an increase in energy expenditure. Taken together, these data suggest that targeting the parasympathetic cholinergic innervation of the liver is a potential therapeutic approach for enhancing hepatic lipid metabolism in obesity and diabetes.

Bile Acids-Based Therapies for Primary Sclerosing Cholangitis: Current Landscape and Future Developments.

Primary sclerosing cholangitis (PSC) is a rare, chronic liver disease with no approved therapies. The ursodeoxycholic acid (UDCA) has been widely used, although there is no evidence that the use of UDCA delays the time to liver transplant or increases survival. Several candidate drugs are currently being developed. The largest group of these new agents is represented by FXR agonists, including obeticholic acid, cilofexor, and tropifexor. Other agents that target bile acid metabolism are ASTB/IBAP inhibitors and fibroblasts growth factor (FGF)19 analogues. Cholangiocytes, the epithelial bile duct cells, play a role in PSC development. Recent studies have revealed that these cells undergo a downregulation of GPBAR1 (TGR5), a bile acid receptor involved in bicarbonate secretion and immune regulation. Additional agents under evaluation are PPARs (elafibranor and seladelpar), anti-itching agents such as MAS-related G-protein-coupled receptors antagonists, and anti-fibrotic and immunosuppressive agents. Drugs targeting gut bacteria and bile acid pathways are also under investigation, given the strong link between PSC and gut microbiota.

Cholic acid activation of GPBAR1 does not induce or exacerbate acute pancreatitis but promotes exocrine pancreatic secretion

Obstruction of bile ducts due to gallstones can lead to biliary acute pancreatitis (BAP). According to Perides et al., G protein-coupled bile acid receptor-1 (GPBAR1) mediates BAP. However, Zi’s findings suggest that GPR39, rather than GPBAR1, mediates TLCAS-induced increases in cytosolic calcium and acinar cell necrosis, casting doubt on the role of GPBAR1 in BAP. Numerous G protein-coupled receptors on pancreatic acinar cells utilize Ca2+ and cyclic adenosine monophosphate (cAMP) as second messengers to manage pancreatic exocrine secretion, with significant cross-talk between these signals. The primary bile acid cholic acid (CA) and its conjugated forms are predominant in the human gallbladder. This study aimed to clarify the role and physiological significance of GPBAR1 by investigating the physiological and pathological effects of CA activation on GPBAR1 in pancreatic acinar cells. Isolated rat pancreatic acinar cells were treated with CA and CCK in vitro to observe the effect of CA-induced cAMP signaling on CCK-induced physiological and pathological calcium signaling. In vivo evaluations involved reverse biliopancreatic duct injections of 5% sodium taurocholate (STC) or 5% CA in rats. CA induced intracellular cAMP signaling in a concentration-dependent manner without increasing the intracellular Ca2+ concentration. CA did not independently cause calcium overload or enzyme activation, nor did it exacerbate calcium overload or enzyme activation from high-dose CCK. Reverse biliopancreatic duct injections of 5% CA did not cause acute pancreatitis in the rats. Transcriptomic analysis revealed that 50 μM CA induced changes in gene expression related to protein synthesis in the endoplasmic reticulum and ribosomes. Furthermore, 50 μM CA accelerated the calcium waves and increased the enzyme secretion induced by CCK. GPBAR1 was found on the basolateral membrane in rat pancreatic tissue rather than near the apical region of acinar cells.GPBAR1 activation is not crucial for BAP activity but may play a role in bile acid regulation of pancreatic exocrine secretion, suggesting that GPBAR1 is a potential therapeutic target for pancreatic exocrine insufficiency.

Thalidomide mitigates Crohn's disease colitis by modulating gut microbiota, metabolites, and regulatory T cell immunity

Thalidomide (THA) is renowned for its potent anti-inflammatory properties. This study aimed to elucidate its underlying mechanisms in the context of Crohn’s disease (CD) development. Mouse colitis models were established by dextran sulfate sodium (DSS) treatment. Fecal microbiota and metabolites were analyzed by metagenomic sequencing and mass spectrometry, respectively. Antibiotic-treated mice served as models for microbiota depletion and transplantation. The expression of Forkhead box P3+ (FOXP3+) Regulatory T cells (Tregs) was measured by flow cytometry and immunohistochemical assay in colitis model and patient cohort. THA inhibited colitis in DSS–treated mice by altering the gut microbiota profile, with an increased abundance of probiotics Bacteroides fragilis (Bf), while pathogenic bacteria were depleted. In addition, THA increased beneficial metabolites bile acids and significantly restored gut barrier function. Transcriptomic profiling revealed that THA inhibited interleukin-17 (IL17), IL1β and cell cycle signaling. Fecal microbiota transplantation from THA-treated mice to microbiota-depleted mice partly recapitulated the effects of THA. Specifically, increased level of gut commensal Bf was observed, correlated with elevated levels of the microbial metabolite 7-Ketolithocholic acid (7-KA) following THA treatment. This microbial metabolite may stable FOXP3 expression by targeting the bile acid receptor farnesol X receptor 1(FXR1) to inhibit autophagy. An interaction between FOXP3 and FXR1 was identified, with binding regions localized to the FOXP3 domain (aa 238-335) and the FXR1 domain (aa 82-222), respectively. Conclusively, THA modulates the gut microbiota and metabolite profiles towards a more beneficial composition, enhances gut barrier function, promotes the differentiation of FOXP3+ Tregs and curbs pro-inflammatory pathways.

Yi-Fei-San-Jie Chinese medicine formula reverses immune escape by regulating deoxycholic acid metabolism to inhibit TGR5/STAT3/PD-L1 axis in lung cancer

BackgroundYi-Fei-San-Jie Formula (YFSJF), a proprietary medicine of the First Affiliated Hospital of Guangzhou University of Chinese Medicine, has been widely used in clinical practice for several years and is currently being tested in randomized controlled trials for early-stage lung cancer in China. However, the mechanisms by which YFSJF affects lung cancer biology, particularly the immune microenvironment and metabolic processes, remain poorly understood. PurposeThis study aims to explore how YFSJF modulates the immune microenvironment and metabolism in lung cancer, specifically its unique role in inhibiting immune evasion by targeting the TGR5/STAT3/PD-L1 pathway, which has not previously been reported. MethodsComputed Tomography (CT) scan was used to assess YFSJF efficacy in patients with lung cancer and a mouse model of urethane-induced lung cancer. Histopathological evaluation, flow cytometry, and metabolomic analysis were used to assess lung tissue structure, immune cell subset changes, and metabolism modulation, respectively. Western blotting and immunohistochemistry were used to detect Ki67, TTF-1, TGR5, STAT3, p-STAT3, and PD-L1 protein expression. Serum cytokines were detected by ELISA. ResultsYFSJF effectively reduced the size of human lung cancer lesions and decreased the tumor burden and improved survival rates in mice. Lung tissue structure was also improved after YFSJF treatment. YFSJF regulated T-cell subsets, particularly by downregulating cells with PD-1-positive expression of CD3+, CD4+, and CD8+, and elevated serum TNF-α, IFN-γ, and GzmB levels. In addition, YFSJF modulated bile acid metabolism, particularly by inhibiting deoxycholic acid metabolism, which participates in immune regulation in lung cancer by acting on the G protein-coupled bile acid receptor TGR5. ConclusionFinally, YFSJF inhibited immune evasion by blocking the TGR5-mediated STAT3/PD-L1 pathway, weakening PD-L1 and PD-1 binding and reviving T-cell immune activity, thereby countering lung cancer immune evasion and exerting anti-tumor effects.

The development of hepatic steatosis depends on the presence of liver-innervating parasympathetic cholinergic neurons in mice fed a high-fat diet.

Hepatic lipid metabolism is regulated by the autonomic nervous system of the liver, with the sympathetic innervation being extensively studied, while the parasympathetic efferent innervation is less understood despite its potential importance. In this study, we investigate the consequences of disrupted brain-liver communication on hepatic lipid metabolism in mice exposed to obesogenic conditions. We found that a subset of hepatocytes and cholangiocytes are innervated by parasympathetic nerve terminals originating from the dorsal motor nucleus of the vagus. The elimination of the brain-liver axis by deleting parasympathetic cholinergic neurons innervating the liver prevents hepatic steatosis and promotes browning of inguinal white adipose tissue (ingWAT). The loss of liver-innervating cholinergic neurons increases hepatic Cyp7b1 expression and fasting serum bile acid levels. Furthermore, knockdown of the G protein-coupled bile acid receptor 1 gene in ingWAT reverses the beneficial effects of the loss of liver-innervating cholinergic neurons, leading to the reappearance of hepatic steatosis. Deleting liver-innervating cholinergic neurons has a small but significant effect on body weight, which is accompanied by an increase in energy expenditure. Taken together, these data suggest that targeting the parasympathetic cholinergic innervation of the liver is a potential therapeutic approach for enhancing hepatic lipid metabolism in obesity and diabetes.

VSV infection and LPS treatment alter serum bile acid profiles, bile acid biosynthesis, and bile acid receptors in mice.

This study focuses on the crosstalk between bile acid (BA) metabolism and immune response in VSV infection and LPS treatment models and depicts the effect of infection on circulating BA profiles, the biosynthesis-related enzymes, and their receptors. These findings provide insights into the effect of infection on BA metabolism and signaling, adding a more comprehensive understanding to the relationship between infection, BA metabolism and immune responses.

Development of dual GPBAR1 agonist and RORγt inverse agonist for the treatment of inflammatory bowel diseases

Inflammatory bowel diseases (IBD), including Crohn's disease and ulcerative colitis, are chronic disorders characterized by dysregulated immune response and persistent inflammation. Recent studies suggest that bile acid receptors, particularly GPBAR1, and the transcription factor RORγt play critical roles in modulating intestinal inflammation. This study evaluates the therapeutic potential of PBT002, a dual GPBAR1 agonist and RORγt inverse agonist, in IBD models. The effects of PBT002 were assessed through in vitro and in vivo experiments. Macrophages and T lymphocytes obtained from the buffy coat were exposed to PBT002 to evaluate its immunomodulatory activity. The beneficial effects in vivo were evaluated in mouse models of colitis induced by TNBS, DSS or DSS + IL-23 using also a Gpbar1 knock-out male mice. PBT002 exhibited an EC50 of 1.2 µM for GPBAR1 and an IC50 of 2.8 µM for RORγt. In in vitro, PBT002 modulated macrophage polarization towards an anti-inflammatory M2 phenotype and reduced Th17 cell markers while increasing Treg markers. In the TNBS-induced colitis model, PBT002 reduced weight loss, CDAI, and colon damage, while it modulated cytokine gene expression towards an anti-inflammatory profile. In GPBAR1-/-, the anti-inflammatory effects of PBT002 were attenuated, indicating partial GPBAR1 dependence. RNA sequencing revealed significant modulation of inflammatory pathways by PBT002. In DSS+IL-23 induced colitis, PBT002 mitigated disease exacerbation, reducing pro-inflammatory cytokine levels and immune cell infiltration. In conclusion, PBT002, a GPBAR1 agonist and RORγt inverse agonist, modulates both the innate and adaptive immune responses to reduce inflammation and disease severity in models of IBD.

A comprehensive 26-color immunophenotyping panel to study the role of the gut-liver axis in chronic liver diseases.

The gut-liver axis includes the bidirectional communication between the gut and the liver, and thus covers signals from liver-to-gut and from gut-to-liver. Disruptions of the gut-liver axis have been associated with the progression of chronic liver diseases, including alcohol-related and metabolic dysfunction-associated steatotic liver disease and cholangiopathies. Immune cells and their expression of pattern recognition receptors, activation markers or immune checkpoints might play an active role in the communication between gut and liver. Here, we present a 26-color full spectrum flow cytometry panel for human cells to decipher the role of circulating immune cells in gut-liver communication during the progression of chronic liver diseases in a non-invasive manner, which has been optimized to be used on patient-derived whole blood samples, the most abundantly available clinical material. Our panel focuses on changes in pattern recognition receptors, including toll-like receptors (TLRs) or Dectin-1, and also includes other immunomodulatory molecules such as bile acid receptors and checkpoint molecules. Moreover, this panel can be utilized to follow the progression of chronic liver diseases and could be used as a tool to evaluate the efficiency of therapeutic targets directed against microbial mediators or modulating immune cell activation.

Unravelling the therapeutic landscape of bile acid-based therapies in gastrointestinal disorders.

Bile acids serve as endogenous ligands for nuclear and cell membrane receptors and play a crucial role in bile acid and lipid metabolism. These detergent-like compounds promote bile flow and aid in the absorption of dietary fats and fat-soluble vitamins in the intestine. Synthesized in the liver as end products of cholesterol catabolism, bile acids exhibit a chemical structure comprising a nucleus and a side chain featuring a carboxyl group, with diverse steric arrangements and potential polar substituents. Critical interactions occur between bile acid species and various nuclear and cell membrane receptors, including the farnesoid X receptor and G-protein-coupled bile acid receptor 1. This research aimed to review the literature on bile acids and their roles in treating different diseases. Currently, numerous investigations are concentrating on specific bile acid species that target nuclear receptors in the gastrointestinal system, aiming to improve the treatment of conditions such as nonalcoholic fatty liver disease. Given the global attention this topic has garnered from research groups, it is considered relatively new, thus anticipating some gaps or incomplete data. Bile acid species have a significant therapeutic promise, especially in their ability to activate or inhibit nuclear receptors, such as farnesoid X receptor. This research provides to offer essential information for scientists and medical practitioners interested in discovering new studies that underscore the importance of bile acids in ameliorating and impeding the progression of disorders. Furthermore, it opens avenues for previously overlooked bile acid-based therapies.

Abstract P166: Genetic Ablation of the Bile Acid Receptor- Takeda G-protein Coupled Receptor 5 (TGR5) Promotes Weight Gain but Lowers Hypertension

Introduction: TGR5 belongs to G-protein coupled receptor family, that mediates bile acid signaling. Activation of TGR5 by bile acids triggers intestinal glucagon-like peptide-1 secretion, whereby pharmacological activation of TGR5 constitutes a promising incretin-based strategy for the treatment of metabolic disorders. Hypertension is one of the hallmark features of metabolic disorders. We previously reported that hypertension is associated with lower conjugated bile acids, which are ligands for TGR5. Therefore, we hypothesized that lack of activation of TGR5-mediated bile acid signaling promotes not only body weight gain, but also hypertension. Methods: CRISPR/Cas9 technology was used to generate Tgr5 -/- rats from hypertensive Dahl Salt-sensitive (S) rats. Twenty-four-hour blood pressure (BP) readings of 8-weeks-old control female Tgr5 +/+ S rats and age-matched female Tgr5 -/- S rats (n=7/group) were monitored by radiotelemetry for 4 weeks. Body weight, food intake, and water intake were recorded every week. At the end of the study, vascular function was examined using wire myography of dorsal and mesenteric resistance arteries, cardiac function was assessed by echocardiography, and microbiota profiling was conducted via fecal 16S rRNA gene sequencing using Miseq. Results: In support of our hypothesis, despite no difference in food and water intake, at 4 weeks, the body weights of Tgr5 -/- S rats were significantly higher compared to Tgr5 +/+ S rats (236.3gm vs. 225.4gm; p&lt;0.01). Surprisingly, in contrast to our hypothesis, at 4 weeks, Tgr5 -/- S rats had significantly lower systolic BP (151.8mmHg vs. 156.9mmHg, p&lt;0.0001), diastolic BP (107.9mmHg vs. 115.5mmHg, p&lt;0.0001), and mean arterial BP (128.8mmHg vs. 134.9mmHg, p&lt;0.0001) compared to Tgr5 +/+ S rats. However, no significant differences were observed either in vascular reactivity or cardiac function between the groups. Interestingly, fecal microbiota analysis revealed that Tgr5 -/- S rats presented with significant remodeling of gut microbiota with lower α-diversity (observed features; p=0.05), b-diversity (Bray-Curtis; p&lt;0.05, Jaccard; p&lt;0.01), and higher relative abundance of the BP-lowering genera Akkermansia . Conclusion: Our study revealed that deletion of TGR5 resulted in weight gain but lowered BP. It implies that activation of TGR5 may be a risk factor for raising BP. The mechanism by which TGR5 regulates BP seem independent of changes in vascular or cardiac function but is likely mediated by gut microbiota.

Zexie-Baizhu Decoction ameliorates non-alcoholic fatty liver disease through gut-adipose tissue crosstalk

Ethnopharmacological relevanceZexie-Baizhu Decoction (AA), a Chinese Classical Formula composed of Alisma orientalis (Sam.) Juzep. and Aractylodes Macrocephala Koidz in the specific ratio of 5:2, has a long history of use in treating metabolic disorders. Recent studies have demonstrated AA's ameliorative effects on non-alcoholic fatty liver disease (NAFLD); however, the mechanism underlying its action on the gut and adipose tissue, key regulators of metabolism, have not been fully explored. Aim of the studyThis study aimed to investigate the mechanisms by which AA regulates the homeostasis of gut and adipose tissue in NAFLD. Materials and methodsAA (1500 mg/kg/day) or vehicle was administrated to the high-fat diet-induced and normal chow-fed mice (C57BL/6J). Plasma, the liver, gut microbiota, bile acids, and short-chain fatty acids in the gut, were systematically investigated. RNA sequencing analysis, reverse transcription quantitative real-time PCR, and Western Blotting were performed on the epididymal white adipose tissues (eWAT) to explore AA's influence on NAFLD. Lipidomics of the liver and eWAT were analyzed by liquid chromatography-mass spectrometry and desorption electrospray ionization mass spectrometry imaging. ResultsOur study demonstrated that AA administration effectively alleviated liver injury induced by NAFLD, as evidenced by reduced hepatic fat accumulation and inflammation. Mechanistically, AA modulated the composition of the gut microbiota, promoting the growth of beneficial bacteria such as Akkermansia muciniphila and restoring the balance between Firmicutes and Bacteroidetes. Furthermore, AA regulated the levels of bile acids and short-chain fatty acids in the intestine, plasma, and liver. Correspondingly in the eWAT, AA administration activated bile acid receptor (Gpbar1) and short-chain fatty acid receptor (Ffar2), facilitating lipid breakdown and attenuating triglyceride accumulation. Transcriptome analysis revealed that AA influenced gene expression related to fatty acid metabolism, thermogenesis, insulin resistance, AMPK signaling, and the tricarboxylic acid (TCA) cycle, thereby improving NAFLD at the transcriptional level. Additionally, AA treatment significantly altered the lipid composition in the liver, reducing levels of diacylglycerols, triacylglycerols, phosphatidylserines, and cholesterol esters, while increasing levels of phosphatidic acids, phosphatidylethanolamines, and sphingomyelins. ConclusionOur study builds a connection between the gut and adipose tissue to understand the mechanism of AA on alleviating NAFLD, providing new insights into the development of targeted therapies for this condition.

Activation of the G Protein-Coupled Bile Acid Receptor TGR5 Modulates the HCP5/miR-139-5p/DDIT4 Axis to Antagonize Cervical Cancer Progression.

A growing body of evidence indicates that the G protein-coupled bile acid receptor, TGR5, plays a critical role in multiple physiological processes ranging from metabolic disorders to cancers. However, the biological functions of TGR5 in cervical cancer (CC) have not been elucidated. Here, using TGR5 knockout mice, we found that a deficiency of TGR5 leads to greater sensitivity to the progression of cervical inflammation. Activation of TGR5 by its specific ligands significantly attenuated the malignant behavior of CC cells. In addition, we found that TGR5 can negatively modulate the expression of lncRNA HCP5 by blocking its transcription activation when mediated by p65. HCP5 was highly expressed in CC tissues, which was positively correlated with the poor prognosis of CC patients. HCP5 knockdown notably restrained CC cell proliferation, colony formation, and migration in vitro, and inhibited tumor growth in vivo. Furthermore, HCP5 can function as the molecular sponge for miR-139-5p to upregulate DNA damage-induced transcript 4 (DDIT4) in CC cells. Murine xenograft studies demonstrated that TGR5 suppressed the tumor formation of CC cells and downregulated HCP5 and DDIT4 while increasing miR-139-5p in the xenografts. Taken together, these findings, for the first time, indicate that TGR5 inhibits CC progression by regulating the HCP5/miR-139-5p/DDIT4 axis, suggesting that it may represent a novel and potent target for CC treatment.

Unveiling structural determinants for FXR antagonism in 1,3,4-trisubstituted-Pyrazol amide derivatives: A multi-scale in silico modelling approach

Non-alcoholic fatty liver disease (NAFLD) is a growing global health concern due to its potential to progress into severe liver diseases. Targeting the bile acid receptor FXR has emerged as a promising strategy for managing NAFLD. Building upon our previous research on FXR partial agonism, the present study investigates a series of 1,3,4-trisubstituted-pyrazol amide derivatives as FXR antagonists, aiming to delineate the structural features for antagonism. By means of 2D-QSAR (quantitative structure-activity relationships) modelling techniques, we elucidated the key structural elements responsible for the antagonistic properties of these derivatives. We then employed QPhAR, an open-access software, to identify key molecular features within the compounds that enhance their antagonistic activity. Additionally, 3D-QSAR modelling allowed us to analyse the steric and electrostatic fields of aligned 3D structures, further refining our understanding of structure-activity relationships. Subsequent molecular dynamics simulations provided insights into the binding mode interactions between the compounds and FXR, with varying potencies, confirming and complementing the findings from 2D-QSAR, pharmacophore, and 3D-QSAR modelling. Particularly, our study highlighted the significance of hydrophobic interactions in conferring potent antagonism by the 1,3,4-trisubstituted-pyrazol amide derivatives against FXR. Overall, this work underscores the potential of 1,3,4-trisubstituted-pyrazol amides as FXR antagonists for NAFLD treatment. Notably, our reliance on open-access software fosters reproducibility and broadens the accessibility of our findings.

Changes in the Bile Acid Pool and Timing of Female Puberty: Potential Novel Role of Hypothalamic TGR5.

The regulation of pubertal timing and reproductive axis maturation is influenced by a myriad of physiologic and environmental inputs yet remains incompletely understood. To contrast differences in bile acid isoform profiles across defined stages of reproductive maturity in humans and a rat model of puberty and to characterize the role of bile acid signaling via hypothalamic expression of bile acid receptor populations in the rodent model. Secondary analysis and pilot studies of clinical cohorts, rodent models, ex vivo analyses of rodent hypothalamic tissues. Bile acid concentrations is the main outcome measure. Lower circulatory conjugated:deconjugated bile acid concentrations and higher total secondary bile acids were observed in postmenarcheal vs pre-/early pubertal adolescents, with similar shifts observed in infantile (postnatal day [PN]14) vs early juvenile (PN21) rats alongside increased tgr5 receptor mRNA expression within the mediobasal hypothalamus of female rats. 16S rRNA gene sequencing of the rodent gut microbiome across postnatal life revealed changes in the gut microbial composition predicted to have bile salt hydrolase activity, which was observed in parallel with the increased deconjugated and increased concentrations of secondary bile acids. We show that TGR5-stimulated GnRH release from hypothalamic explants is mediated through kisspeptin receptors and that early overexpression of human-TGR5 within the arcuate nucleus accelerates pubertal onset in female rats. Bile acid isoform shifts along stages of reproductive maturation are conserved across rodents and humans, with preclinical models providing mechanistic insight for the neuroendocrine-hepatic-gut microbiome axis as a potential moderator of pubertal timing in females.