Farnesoid X receptor activation increases reverse cholesterol transport by modulating bile acid composition and cholesterol absorption in mice

Geniposide for treating atherosclerotic cardiovascular disease: a systematic review on its biological characteristics, pharmacology, pharmacokinetics, and toxicology

In recent years, the prevalence and fatality rates of atherosclerotic cardiovascular disease have not only shown a consistent rise that cannot be ignored, but have also become a pressing social health problem that requires urgent attention. While interventional surgery and drug therapy offer significant therapeutic results, they often come with common side effects. Geniposide, an active component extracted from the Chinese medicine Gardenia jasminoides Ellis, shows promise in the management of cardiac conditions. This review comprehensively outlines the underlying pharmacological mechanisms by which geniposide exerts its effects on atherosclerosis. Geniposide exhibits a range of beneficial effects including alleviating inflammation, inhibiting the development of macrophage foam cells, improving lipid metabolism, and preventing platelet aggregation and thrombosis. It also demonstrates mitochondrial preservation, anti-apoptotic effects, and modulation of autophagy. Moreover, geniposide shows potential in improving oxidative stress and endoplasmic reticulum stress by maintaining the body's antioxidant and oxidative balance. Additionally, this review comprehensively details the biological properties of geniposide, including methods of extraction and purification, as well as its pharmacokinetics and toxicological characteristics. It further discusses the clinical applications of related biopharmaceuticals, emphasizing the potential of geniposide in the prevention and treatment of atherosclerotic cardiovascular diseases. Furthermore, it highlights the limitations of current research, aiming to provide insights for future studies.

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.

Multiomics to Characterize the Molecular Events Underlying Impaired Glucose Tolerance in FXR-Knockout Mice

The prevalence of different metabolic syndromes has grown globally, and the farnesoid X receptor (FXR), a metabolic homeostat for glucose, lipid, and bile acid metabolisms, may serve an important role in the progression of metabolic disorders. Glucose intolerance by FXR deficiency was previously reported and observed in our study, but the underlying biology remained unclear. To investigate the ambiguity, we collected the nontargeted profiles of the fecal metaproteome, serum metabolome, and liver proteome in Fxr-null (Fxr-/-) and wild-type (WT) mice with LC-HRMS. FXR deficiency showed a global impact on the different molecular levels we monitored, suggesting its serious disruption in the gut microbiota, hepatic metabolism, and circulating biomolecules. The network and enrichment analyses of the dysregulated metabolites and proteins suggested the perturbation of carbohydrate and lipid metabolism by FXR deficiency. Fxr-/- mice presented lower levels of hepatic proteins involved in glycogenesis. The impairment of glycogenesis by an FXR deficiency may leave glucose to accumulate in the circulation, which may deteriorate glucose tolerance. Lipid metabolism was dysregulated by FXR deficiency in a structural-dependent manner. Fatty acid β-oxidations were alleviated, but cholesterol metabolism was promoted by an FXR deficiency. Together, we explored the molecular events associated with glucose intolerance by impaired FXR with integrated novel multiomic data.

Nuclear factor interleukin 3 and metabolic dysfunction-associated fatty liver disease development

This study investigates sex-specific effects in a gain-of-function model to evaluate Nfil3 function in relation to high-fat diet (HFD)-induced metabolic dysfunction-associated steatotic liver disease (MASLD) and gut microbiota (GM)-induced alterations in the bile acid (BA) profile. MASLD is induced in both wild type and Nfil3-deficient (NKO) C57BL/6 J mice through an HFD. The hepatic immune response is evaluated using flow cytometry, revealing that NKO mice exhibit lower body weight, serum triglyceride (TG) levels, tissue injury, inflammation, and fat accumulation. The Nfil3 deletion reduces macrophage counts in fibrotic liver tissues, decreases proinflammatory gene and protein expression, and diminishes gut barrier function. Alpha and beta diversity analysis reveal increased GM alpha diversity across different sexes. The Nfil3 gene deletion modifies the BA profile, suggesting that negative feedback through the Nfil3-FXR-FGF15 axis facilitates BA recycling from the liver via enterohepatic circulation. Therefore, inhibiting Nfil3 in the liver offers a viable treatment approach for MASLD.

Obeticholic acid's effect on HDL function in MASH varies by diabetic status

Inflammation and oxidative stress are the key factors in the pathogenesis of both metabolic dysfunction-associated steatohepatitis (MASH) and atherosclerosis. Obeticholic acid (OCA), a farnesoid X receptor (FXR) agonist, improves hepatic inflammation and fibrosis in patients with MASH. However, it also reduces HDL cholesterol, suggesting that OCA may increase cardiovascular disease (CVD) risk in patients with MASH. We assessed HDL cholesterol efflux function, antioxidant (paraoxonase and ceruloplasmin activity), pro-inflammatory index, and particle sizes in a small group of patients with and without diabetes (n = 10/group) at baseline and after 18 months of OCA treatment. Patients on lipid-lowering medications (statins, fibrates) were excluded. At baseline, ferritin levels were higher in patients with MASH without diabetes (336.5 [157.0, 451.0] vs. 83 [36.0, 151.0] ng/mL, p < 0.005). Markers of HDL functions were similar in both groups. OCA therapy significantly improved liver histology and liver enzymes but increased alkaline phosphatase levels in nondiabetic patients with MASH (p < 0.05). However, it did not have any significant effect on cholesterol efflux and the antioxidant paraoxonase functions. In nondiabetics, ceruloplasmin (CP) antioxidant activity decreased (p < 0.005) and the pro-inflammatory index of HDL increased (p < 0.005) due to OCA therapy. In contrast, in diabetics, OCA increased levels of pre-β-HDL-the HDL particles enhanced protective capacity (p = 0.005) with no alteration in HDL functionality. In all patients, serum glucose levels were negatively correlated with OCA-induced change in pro-inflammatory function in HDL (p < 0.001), which was primarily due to diabetes (p = 0.05). These preliminary results suggest a distinct effect of OCA therapy on diabetic and nondiabetic patients with MASH and warrant a future large-scale study.

The Gut Microbiome Affects Atherosclerosis by Regulating Reverse Cholesterol Transport

The human system's secret organ, the gut microbiome, has received considerable attention. Emerging research has yielded substantial scientific evidence indicating that changes in gut microbial composition and microbial metabolites may contribute to the development of atherosclerotic cardiovascular disease. The burden of cardiovascular disease on healthcare systems is exacerbated by atherosclerotic cardiovascular disease, which continues to be the leading cause of mortality globally. Reverse cholesterol transport is a powerful protective mechanism that effectively prevents excessive accumulation of cholesterol for atherosclerotic cardiovascular disease. It has been revealed how the gut microbiota modulates reverse cholesterol transport in patients with atherosclerotic risk. In this review, we highlight the complex interactions between microbes, their metabolites, and their potential impacts in reverse cholesterol transport. We also explore the feasibility of modulating gut microbes and metabolites to facilitate reverse cholesterol transport as a novel therapy for atherosclerosis.

Neoagarotetraose Alleviates Atherosclerosis via Modulating Cholesterol and Bile Acid Metabolism in ApoE-/- Mice

Atherosclerosis is closely associated with metabolic disorders such as cholesterol accumulation, bile acid metabolism, and gut dysbiosis. Neoagarotetraose supplementation has been shown to inhibit obesity and alleviate type 2 diabetes, but its effects on modulating the development of atherosclerosis remain unexplored. Therefore, the present study was conducted to investigate the protective effects and potential mechanisms of neoagarotetraose on high-fat, high-cholesterol diet (HFHCD)-induced atherosclerosis in ApoE-/- mice. The results showed that neoagarotetraose supplementation decreased the atherosclerotic lesion area by 50.1% and the aortic arch lesion size by 80.4% compared to the HFHCD group. Furthermore, neoagarotetraose supplementation led to a significant reduction in hepatic lipid content, particularly non-high-density lipoprotein cholesterol. It also resulted in a substantial increase in total bile acid content in both urine and fecal samples by 3.0-fold and 38.7%, respectively. Moreover, neoagarotetraose supplementation effectively downregulated the intestinal farnesoid X receptor by 35.8% and modulated the expressions of its associated genes in both the liver and intestine. In addition, correlation analysis revealed strong associations between gut microbiota composition and fecal bile acid levels. These findings highlight the role of gut microbiota in neoagarotetraose-mitigating atherosclerosis in HFHCD-fed ApoE-/- mice. This study indicates the potential of neoagarotetraose as a functional dietary supplement for the prevention of atherosclerosis.

Unveiling the oral-gut connection: chronic apical periodontitis accelerates atherosclerosis via gut microbiota dysbiosis and altered metabolites in apoE-/- Mice on a high-fat diet

The aim of this study was to explore the impact of chronic apical periodontitis (CAP) on atherosclerosis in apoE-/- mice fed high-fat diet (HFD). This investigation focused on the gut microbiota, metabolites, and intestinal barrier function to uncover potential links between oral health and cardiovascular disease (CVD). In this study, CAP was shown to exacerbate atherosclerosis in HFD-fed apoE-/- mice, as evidenced by the increase in plaque size and volume in the aortic walls observed via Oil Red O staining. 16S rRNA sequencing revealed significant alterations in the gut microbiota, with harmful bacterial species thriving while beneficial species declining. Metabolomic profiling indicated disruptions in lipid metabolism and primary bile acid synthesis, leading to elevated levels of taurochenodeoxycholic acid (TCDCA), taurocholic acid (TCA), and tauroursodeoxycholic acid (TDCA). These metabolic shifts may contribute to atherosclerosis development. Furthermore, impaired intestinal barrier function, characterized by reduced mucin expression and disrupted tight junction proteins, was observed. The increased intestinal permeability observed was positively correlated with the severity of atherosclerotic lesions, highlighting the importance of the intestinal barrier in cardiovascular health. In conclusion, this research underscores the intricate interplay among oral health, gut microbiota composition, metabolite profiles, and CVD incidence. These findings emphasize the importance of maintaining good oral hygiene as a potential preventive measure against cardiovascular issues, as well as the need for further investigations into the intricate mechanisms linking oral health, gut microbiota, and metabolic pathways in CVD development.

Bile acid metabolism and signaling in health and disease: molecular mechanisms and therapeutic targets

Bile acids, once considered mere dietary surfactants, now emerge as critical modulators of macronutrient (lipid, carbohydrate, protein) metabolism and the systemic pro-inflammatory/anti-inflammatory balance. Bile acid metabolism and signaling pathways play a crucial role in protecting against, or if aberrant, inducing cardiometabolic, inflammatory, and neoplastic conditions, strongly influencing health and disease. No curative treatment exists for any bile acid influenced disease, while the most promising and well-developed bile acid therapeutic was recently rejected by the FDA. Here, we provide a bottom-up approach on bile acids, mechanistically explaining their biochemistry, physiology, and pharmacology at canonical and non-canonical receptors. Using this mechanistic model of bile acids, we explain how abnormal bile acid physiology drives disease pathogenesis, emphasizing how ceramide synthesis may serve as a unifying pathogenic feature for cardiometabolic diseases. We provide an in-depth summary on pre-existing bile acid receptor modulators, explain their shortcomings, and propose solutions for how they may be remedied. Lastly, we rationalize novel targets for further translational drug discovery and provide future perspectives. Rather than dismissing bile acid therapeutics due to recent setbacks, we believe that there is immense clinical potential and a high likelihood for the future success of bile acid therapeutics.

High temperature and humidity in the environment disrupt bile acid metabolism, the gut microbiome, and GLP-1 secretion in mice

High temperature and humidity in the environment are known to be associated with discomfort and disease, yet the underlying mechanisms remain unclear. We observed a decrease in plasma glucagon-like peptide-1 levels in response to high-temperature and humidity conditions. Through 16S rRNA gene sequencing, alterations in the gut microbiota composition were identified following exposure to high temperature and humidity conditions. Notably, changes in the gut microbiota have been implicated in bile acid synthesis. Further analysis revealed a decrease in lithocholic acid levels in high-temperature and humidity conditions. Subsequent in vitro experiments demonstrated that lithocholic acid increases glucagon-like peptide-1 secretion in NCI-H716 cells. Proteomic analysis indicated upregulation of farnesoid X receptor expression in the ileum. In vitro experiments revealed that the combination of lithocholic acid with farnesoid X receptor inhibitors resulted in a significant increase in GLP-1 levels compared to lithocholic acid alone. In this study, we elucidate the mechanism by which reduced lithocholic acid suppresses glucagon-like peptide 1 via farnesoid X receptor activation under high-temperature and humidity condition.

Hepatic FOXA3 overexpression prevents Western diet-induced obesity and MASH through TGR5

Forkhead transcription factor 3 (FOXA3) has been shown to regulate metabolism and development. Hepatic FOXA3 is reduced in obesity and fatty liver disease. However, the role of hepatic FOXA3 in regulating obesity or steatohepatitis remains to be investigated. In this work, C57BL/6 mice were i.v. injected with AAV8-ALB-FOXA3 or the control virus. The mice were then fed a chow or Western diet for 16 weeks. The role of hepatic FOXA3 in energy metabolism and steatohepatitis was investigated. Plasma bile acid composition and the role of Takeda G protein-coupled receptor 5 (TGR5) in mediating the metabolic effects of FOXA3 were determined. Overexpression of hepatic FOXA3 reduced hepatic steatosis in chow-fed mice and attenuated Western diet-induced obesity and steatohepatitis. FOXA3 induced lipolysis and inhibited hepatic genes involved in bile acid uptake, resulting in elevated plasma bile acids. The beneficial effects of hepatic FOXA3 overexpression on Western diet-induced obesity and steatohepatitis were abolished in Tgr5-/- mice. Our data demonstrate that overexpression of hepatic FOXA3 prevents Western diet-induced obesity and steatohepatitis via activation of TGR5.

Chronic sucralose consumption inhibits farnesoid X receptor signaling and perturbs lipid and cholesterol homeostasis in the mouse livers, potentially by altering gut microbiota functions

Sucralose has raised concerns regarding its safety and recent studies have demonstrated that sucralose consumption can disrupt the normal gut microbiome and alter metabolic profiles in mice. However, the extent to which this perturbation affects the functional interaction between the microbiota and the host, as well as its potential impact on host health, remains largely unexplored. Here, we aimed to investigate whether chronic sucralose consumption, at levels within the Acceptable Daily Intake (ADI), could disturb key gut microbial functions and lead to adverse health effects in mice. Following six-month sucralose consumption, several bacterial genera associated with bile acid metabolism were decreased, including Lactobacillus and Ruminococcus. Consequently, the richness of secondary bile acid biosynthetic pathway and bacterial bile salt hydrolase gene were decreased in the sucralose-treated gut microbiome. Compared to controls, sucralose-consuming mice exhibited significantly lower ratios of free bile acids and taurine-conjugated bile acids in their livers. Additionally, several farnesoid X receptor (FXR) agonists were decreased in sucralose-treated mice. This reduction in hepatic FXR activation was associated with altered expression of down-stream genes, in the liver. Moreover, the expression of key lipogenic genes was up-regulated in the livers of sucralose-treated mice. Changes in hepatic lipid profiles were also observed, characterized by lower ceramide levels, a decreased PC/PE ratio, and a mildly increase in lipid accumulation. Additionally, sucralose-consumed mice exhibited higher hepatic cholesterol level compared to control mice, with up-regulation of cholesterol efflux genes and down-regulation of genes associated with reverse cholesterol transport. In conclusion, chronic sucralose consumption disrupts FXR signaling activation and perturbs hepatic lipid and cholesterol homeostasis, potentially by diminishing the bile acid metabolic capacity of the gut microbiome. These findings shed light on the complex interplay between sucralose, the gut microbiota, and host metabolism, raising important questions about the safety of its long-term consumption.

Natural Products in the Modulation of Farnesoid X Receptor Against Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a global health concern with a high prevalence and increasing economic burden, but official medicine remains unavailable. Farnesoid X receptor (FXR), a nuclear receptor member, is one of the most promising drug targets for NAFLD therapy that plays a crucial role in modulating bile acid, glucose, and lipid homeostasis, as well as inhibits hepatic inflammation and fibrosis. However, the rejection of the FXR agonist, obecholic acid, by the Food and Drug Administration for treating hepatic fibrosis raises a question about the functions of FXR in NAFLD progression and the therapeutic strategy to be used. Natural products, such as FXR modulators, have become the focus of attention for NAFLD therapy with fewer adverse reactions. The anti-NAFLD mechanisms seem to act as FXR agonists and antagonists or are involved in the FXR signaling pathway activation, indicating a promising target of FXR therapeutic prospects using natural products. This review discusses the effective mechanisms of FXR in NAFLD alleviation, and summarizes currently available natural products such as silymarin, glycyrrhizin, cycloastragenol, berberine, and gypenosides, for targeting FXR, which can facilitate development of naturally targeted drug by medicinal specialists for effective treatment of NAFLD.

A review on SIRT3 and its natural small molecule activators as a potential Preventive and therapeutic target

Sirtuins (SIRTs) were originally characterized by yeast Sir2 as a lifespan regulator that is conserved in all three structural domains of bacteria, archaea and eukaryotes and belong to histone deacetylases consisting of seven members (SIRT1-SIRT7). Surprisingly, SIRTs have been shown to play important regulatory roles in almost all cellular functions, including mitochondrial biogenesis, oxidative stress, inflammation, cell growth, energy metabolism, neural function, and stress resistance. Among the SIRT members, sirtuin 3 (SIRT3) is one of the most important deacetylases that regulates the mitochondrial acetylation and plays a role in pathological processes, such as metabolism, DNA repair, oxidative stress, apoptosis and ferroptosis. Therefore, SIRT3 is considered as a potential target for the treatment of a variety of pathological diseases, including metabolic diseases, neurodegenerative diseases, age-related diseases and others. Furthermore, the isolation, screening, and development of SIRT3 signaling agonists, especially from natural products, have become a widely investigated objective. This paper describes the structure of SIRT3 protein, discusses the pathological process of SIRT3-mediated acetylation modification, and reviews the role of SIRT3 in diseases, SIRT3 activators and its related disease studies.

Bile salt signaling and bile salt-based therapies in cardiometabolic disease

Bile salts have an established role in the emulsification and intestinal absorption of dietary lipids, and their homeostasis is tightly controlled by various transporters and regulators in the enterohepatic circulation. Notably, emerging evidence points toward bile salts as major modulators of cardiometabolic disease (CMD), an umbrella disease of disorders affecting the heart and blood vessels that is caused by systemic metabolic diseases such as Type 2 diabetes mellitus (T2DM) and metabolic dysfunction-associated steatotic liver disease (MASLD), the latter encompassing also metabolic dysfunction-associated steatohepatitis (MASH). The underlying mechanisms of protective effects of bile salts are their hormonal properties, enabling them to exert versatile metabolic effects by activating various bile salt-responsive signaling receptors with the nuclear farnesoid X receptor (FXR) and the Takeda G-protein-coupled receptor 5 (TGR5) as most extensively investigated. Activation of FXR and TGR5 is involved in the regulation of glucose, lipid and energy metabolism, and inflammation. Bile salt-based therapies directly targeting FXR and TGR5 signaling have been evaluated for their therapeutic potential in CMD. More recently, therapeutics targeting bile salt transporters thereby modulating bile salt localization, dynamics, and signaling, have been developed and evaluated in CMD. Here, we discuss the current knowledge on the contribution of bile salt signaling in the pathogenesis of CMD and the potential of bile salt-based therapies for the treatment of CMD.

Chlorogenic acid regulates the expression of NPC1L1 and HMGCR through PXR and SREBP2 signaling pathways and their interactions with HSP90 to maintain cholesterol homeostasis

BACKGROUND

Hypercholesterolemia is widely implicated in the etiology of coronary heart disease, stroke, and dementia. Evidence suggests that chlorogenic acid (CA) reduces the risk of cardiovascular disease.

PURPOSE

The current study aims to explore the underlying molecular mechanism of CA in lowering cholesterol based on pregnane X receptor (PXR) and sterol regulatory element-binding protein 2 (SREBP2) regulatory pathways and their interactions with heat shock protein 90 (HSP90).

METHODS

A hypercholesterolemic mouse model, HepG2 and Caco2 cell models, metabolomics analysis, and co-immunoprecipitation (COIP) were used to study the mechanism of CA lowering cholesterol.

RESULTS

Treatment of the hypercholesterolemic mice with CA for 12 weeks significantly reduced body weight, blood lipid, hepatic lipid accumulation, and increased lipid excretion. The nuclear aggregation of PXR and SREBP2 was inhibited simultaneously. In addition, the expression of downstream target genes, including Niemann-pick C1-like 1 (NPC1L1) and 3‑hydroxy-3-methylglutaryl-CoA reductase (HMGCR), was downregulated after CA administration. Furthermore, in HepG2 and Caco2 cell models, CA reduced intracellular cholesterol levels by inhibiting the nuclear translocation of PXR and SREBP2 and the expression of NPC1L1 and HMGCR. SREBP2 interacts with PXR through HSP90, and CA reduces the binding stability of SREBP2 and HSP90 and enhances the binding of PXR and HSP90, thus reducing the nuclear accumulation of SREBP2 and PXR simultaneously. Moreover, CA promoted the phosphorylation of AMP-activated protein kinase (AMPK) and its binding to SREBP2. This was not conducive to the binding of HSP90 and SREBP2 but enhanced the binding of HSP90 and PXR, thereby inhibiting the nuclear translocation of SREBP2 and PXR and reducing intracellular cholesterol levels. However, no noticeable direct binding between AMPK and PXR was observed.

CONCLUSION

CA downregulates NPC1L1 and HMGCR expression by acting on the AMPK/SREBP2 direct pathway and the AMPK/SREBP2/HSP90/PXR indirect pathway, thus retaining cholesterol homeostasis.

Restraint stress promotes nonalcoholic steatohepatitis by regulating the farnesoid X receptor/NLRP3 signaling pathway

Psychological stress promotes nonalcoholic steatohepatitis (NASH) development. However, the pathogenesis of psychological stress-induced NASH remains unclear. This study aims to explore the underlying mechanism of restraint stress-induced NASH, which mimics psychological stress, and to discover potential NASH candidates. Methionine choline deficient diet- and high fat diet-induced hepatosteatotic mice are subjected to restraint stress to induce NASH. The mice are administrated with Xiaoyaosan granules, NOD-like receptor family pyrin domain containing 3 (NLRP3) inhibitors, farnesoid X receptor (FXR) agonists, or macrophage scavengers. Pathological changes and NLRP3 signaling in the liver are determined. These results demonstrate that restraint stress promotes hepatic inflammation and fibrosis in hepatosteatotic mice. Restraint stress increases the expressions of NLRP3, Caspase-1, Gasdermin D, interleukin-1β, cholesterol 7α-hydroxylase, and sterol 12α-hydroxylase and decreases the expression of FXR in NASH mice. Xiaoyaosan granules reverse hepatic inflammation and fibrosis and target FXR and NLRP3 signals. In addition, inhibition of NLRP3 reduces the NLRP3 inflammasome and liver damage in mice with restraint stress-induced NASH. Elimination of macrophages and activation of FXR also attenuate inflammation and fibrosis by inhibiting NLRP3 signaling. However, NLRP3 inhibitors or macrophage scavengers fail to affect the expression of FXR. In conclusion, restraint stress promotes NASH-related inflammation and fibrosis by regulating the FXR/NLRP3 signaling pathway. Xiaoyaosan granules, NLRP3 inhibitors, FXR agonists, and macrophage scavengers are potential candidates for the treatment of psychological stress-related NASH.

Decreased FXR Agonism in the Bile Acid Pool Is Associated with Impaired FXR Signaling in a Pig Model of Pediatric NAFLD

The objective of this study was to investigate whether the impairment of farnesoid X receptor (FXR)-fibroblast growth factor 19 (FGF19) signaling in juvenile pigs with non-alcoholic fatty liver disease (NAFLD) is associated with changes in the composition of the enterohepatic bile acid pool. Eighteen 15-day-old Iberian pigs, pair-housed in pens, were allocated to receive either a control (CON) or high-fructose, high-fat (HFF) diet. Animals were euthanized in week 10, and liver, blood, and distal ileum (DI) samples were collected. HFF-fed pigs developed NAFLD and had decreased FGF19 expression in the DI and lower FGF19 levels in the blood. Compared with the CON, the HFF diet increased the total cholic acid (CA) and the CA to chenodeoxycholic acid (CDCA) ratio in the liver, DI, and blood. CA and CDCA levels in the DI were negatively and positively correlated with ileal FGF19 expression, respectively, and blood levels of FGF19 decreased with an increasing ileal CA to CDCA ratio. Compared with the CON, the HFF diet increased the gene expression of hepatic 12-alpha-hydrolase, which catalyzes the synthesis of CA in the liver. Since CA species are weaker FXR ligands than CDCA, our results suggest that impairment of FXR-FGF19 signaling in NAFLD pigs is associated with a decrease in FXR agonism in the bile acid pool.

The contributions of bacteria metabolites to the development of hepatic encephalopathy

Over 20% of mortality during acute liver failure is associated with the development of hepatic encephalopathy (HE). Thus, HE is a complication of acute liver failure with a broad spectrum of neuropsychiatric abnormalities ranging from subclinical alterations to coma. HE is caused by the diversion of portal blood into systemic circulation through portosystemic collateral vessels. Thus, the brain is exposed to intestinal-derived toxic substances. Moreover, the strategies to prevent advancement and improve the prognosis of such a liver-brain disease rely on intestinal microbial modulation. This is supported by the findings that antibiotics such as rifaximin and laxative lactulose can alleviate hepatic cirrhosis and/or prevent HE. Together, the significance of the gut-liver-brain axis in human health warrants attention. This review paper focuses on the roles of bacteria metabolites, mainly ammonia and bile acids (BAs) as well as BA receptors in HE. The literature search conducted for this review included searches for phrases such as BA receptors, BAs, ammonia, farnesoid X receptor (FXR), G protein-coupled bile acid receptor 1 (GPBAR1 or TGR5), sphingosine-1-phosphate receptor 2 (S1PR2), and cirrhosis in conjunction with the phrase hepatic encephalopathy and portosystemic encephalopathy. PubMed, as well as Google Scholar, was the search engines used to find relevant publications.

Effects of glyphosate exposure on gut-liver axis: Metabolomic and mechanistic analysis in grass carp (Ctenopharyngodon idellus)

Glyphosate, one of the most widely used herbicide worldwide, is potentially harmful to non-target aquatic organisms. However, the environmental health risks regarding impacts on metabolism homeostasis and underlying mechanisms remain unclear. Here we investigated bioaccumulation, metabolism disorders and mechanisms in grass carp after exposure to glyphosate. Higher accumulation of glyphosate and its major metabolite, aminomethylphosphonic acid, in the gut was detected. Intestinal inflammation, barrier damage and hepatic steatosis were caused by glyphosate exposure. Lipid metabolism disorder was confirmed by the decreased triglyceride, increased total cholesterol and lipoproteins in serum and decreased visceral fat. Metabolomics analysis found that glyphosate exposure significantly inhibited bile acids biosynthesis in liver with decreased total bile acids content, which was further supported by significant downregulations of cyp27a1, cyp8b1 and fxr. Moreover, the dysbiosis of gut microbiota contributed to the inflammation in liver and gut by increasing lipopolysaccharide, as well as to the declined bile acids circulation by reducing secondary bile acids. These results indicated that exposure to environmental levels of glyphosate generated higher bioaccumulation in gut, where evoked enterohepatic injury, intestinal microbiota dysbiosis and disturbed homeostasis of bile acids metabolism; then the functional dysregulation of the gut-liver axis possibly resulted in ultimate lipid metabolism disorder. These findings highlight the metabolism health risks of glyphosate exposure to fish in aquatic environment.

Humanized mouse liver reveals endothelial control of essential hepatic metabolic functions

Hepatocytes, the major metabolic hub of the body, execute functions that are human-specific, altered in human disease, and currently thought to be regulated through endocrine and cell-autonomous mechanisms. Here, we show that key metabolic functions of human hepatocytes are controlled by non-parenchymal cells (NPCs) in their microenvironment. We developed mice bearing human hepatic tissue composed of human hepatocytes and NPCs, including human immune, endothelial, and stellate cells. Humanized livers reproduce human liver architecture, perform vital human-specific metabolic/homeostatic processes, and model human pathologies, including fibrosis and non-alcoholic fatty liver disease (NAFLD). Leveraging species mismatch and lipidomics, we demonstrate that human NPCs control metabolic functions of human hepatocytes in a paracrine manner. Mechanistically, we uncover a species-specific interaction whereby WNT2 secreted by sinusoidal endothelial cells controls cholesterol uptake and bile acid conjugation in hepatocytes through receptor FZD5. These results reveal the essential microenvironmental regulation of hepatic metabolism and its human-specific aspects.

Dihydromyricetin supplementation improves ethanol-induced lipid accumulation and inflammation

Introduction

Excessive alcohol consumption leads to a myriad of detrimental health effects, including alcohol-associated liver disease (ALD). Unfortunately, no available treatments exist to combat the progression of ALD beyond corticosteroid administration and/or liver transplants. Dihydromyricetin (DHM) is a bioactive polyphenol and flavonoid that has traditionally been used in Chinese herbal medicine for its robust antioxidant and anti-inflammatory properties. It is derived from many plants, including Hovenia dulcis and is found as the active ingredient in a variety of popular hangover remedies. Investigations utilizing DHM have demonstrated its ability to alleviate ethanol-induced disruptions in mitochondrial and lipid metabolism, while demonstrating hepatoprotective activity.

Methods

Female c57BL/6J mice (n = 12/group) were treated using the Lieber DeCarli forced-drinking and ethanol (EtOH) containing liquid diet, for 5 weeks. Mice were randomly divided into three groups: (1) No-EtOH, (2) EtOH [5% (v/v)], and (3) EtOH [5% (v/v)] + DHM (6 mg/mL). Mice were exposed to ethanol for 2 weeks to ensure the development of ALD pathology prior to receiving dihydromyricetin supplementation. Statistical analysis included one-way ANOVA along with Bonferroni multiple comparison tests, where p ≤ 0.05 was considered statistically significant.

Results

Dihydromyricetin administration significantly improved aminotransferase levels (AST/ALT) and reduced levels of circulating lipids including LDL/VLDL, total cholesterol (free cholesterol), and triglycerides. DHM demonstrated enhanced lipid clearance by way of increased lipophagy activity, shown as the increased interaction and colocalization of p62/SQSTM-1, LC3B, and PLIN-1 proteins. DHM-fed mice had increased hepatocyte-to-hepatocyte lipid droplet (LD) heterogeneity, suggesting increased neutralization and sequestration of free lipids into LDs. DHM administration significantly reduced prominent pro-inflammatory cytokines commonly associated with ALD pathology such as TNF-α, IL-6, and IL-17.

Discussion

Dihydromyricetin is commercially available as a dietary supplement. The results of this proof-of-concept study demonstrate its potential utility and functionality as a cost-effective and safe candidate to combat inflammation and the progression of ALD pathology.

Diosgenin attenuates nonalcoholic hepatic steatosis through the hepatic FXR-SHP-SREBP1C/PPARα/CD36 pathway

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide and has no approved treatment. The hepatic farnesoid X receptor (FXR) is one of the most promising therapeutic targets for NAFLD. Diosgenin (DG), a natural compound extracted from Chinese herbal medicine, is very effective in preventing metabolic diseases. Our research aims to determine the effects and molecular mechanisms of DG on NAFLD in vivo and in vitro. The effect of DG on hepatic steatosis was evaluated in Sprague‒Dawley (SD) rats induced by a high-fat diet (HFD) and in HepG2 cells exposed to free fatty acids (FFAs, sodium oleate:sodium palmitate = 2:1). DG treatment efficiently managed hepatic lipid deposition in vivo and in vitro. Mechanistically, DG upregulated the expression of FXR and small heterodimer partner (SHP) and downregulated the expression of genes involved in hepatic de novo lipogenesis (DNL), including sterol regulatory element-binding protein 1C (SREBP1C), acetyl-CoA carboxylase 1 (ACC1), and fatty acid synthase (FASN). Moreover, DG promoted the expression of peroxisome proliferator-activated receptor alpha (PPARα), which is related to fatty acid oxidation. In addition, DG inhibited the expression of the CD36 molecule (CD36) related to fatty acid uptake. However, hepatic FXR silencing weakened the regulatory effects of DG on these genes. Collectively, our data show that DG has a good effect on alleviating nonalcoholic hepatic steatosis via the hepatic FXR-SHP-SREBP1C/PPARα/CD36 pathway. DG promises to be a novel candidate FXR activator that can be utilized to treat NAFLD.

Fecal metabolomics analysis for deciphering the lipid-lowering effect of Qizhi capsule on high-fat feed induced hyperlipidemia

ETHNOPHARMACOLOGICAL RELEVANCE

Qizhi capsule (QZC), a Chinese patent drug, has been utilized to treat hyperlipidemia.

AIM OF STUDY

The present study aims to investigate the lipid-lowering effect of QZC, as well as the mechanism of action for treating hyperlipidemia.

MATERIALS AND METHODS

High-fat diet (HFD) induced hyperlipidemia rats were administrated with different doses of QZC for 28 days, and atorvastatin calcium tablets was used as the positive control. Serum total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels were used to evaluate the effectiveness of QZC treatment. The metabolic profiles of feces were analyzed by UPLC-MS-based metabolomics approach coupled with multivariate data analysis.

RESULTS

The levels of serum TC, TG, LDL-C, and HDL-C were significantly reversed in QZC treatment groups, showing a similar or even better treatment effect compared with the atorvastatin calcium group. Thirty-two potential fecal biomarkers related to hyperlipidemia were identified. QZC could partially recover the disturbed metabolic pathways of alpha-linolenic acid metabolism, sphingolipid metabolism, glycerophospholipid metabolism, and glycosylphosphatidylinositol (GPI)-anchor biosynthesis. Meanwhile, the signal pathways of regulation of lipid metabolism by peroxisome proliferator-activated receptor α (PPARα), PPARα activates gene expression, and transcriptional regulation of white adipocyte differentiation can be also regulated by QZC.

CONCLUSION

The lipid-lowering effect of QZC was confirmed by both serum biochemistry and metabolomics analysis. The beneficial effects of QZC were mainly attributed to the correction of metabolic disorders and the maintenance of the dynamic balance of metabolites.

Emerging Roles of Gut Microbial Modulation of Bile Acid Composition in the Etiology of Cardiovascular Diseases

Despite advances in preventive measures and treatment options, cardiovascular disease (CVD) remains the number one cause of death globally. Recent research has challenged the traditional risk factor profile and highlights the potential contribution of non-traditional factors in CVD, such as the gut microbiota and its metabolites. Disturbances in the gut microbiota have been repeatedly associated with CVD, including atherosclerosis and hypertension. Mechanistic studies support a causal role of microbiota-derived metabolites in disease development, such as short-chain fatty acids, trimethylamine-N-oxide, and bile acids, with the latter being elaborately discussed in this review. Bile acids represent a class of cholesterol derivatives that is essential for intestinal absorption of lipids and fat-soluble vitamins, plays an important role in cholesterol turnover and, as more recently discovered, acts as a group of signaling molecules that exerts hormonal functions throughout the body. Studies have shown mediating roles of bile acids in the control of lipid metabolism, immunity, and heart function. Consequently, a picture has emerged of bile acids acting as integrators and modulators of cardiometabolic pathways, highlighting their potential as therapeutic targets in CVD. In this review, we provide an overview of alterations in the gut microbiota and bile acid metabolism found in CVD patients, describe the molecular mechanisms through which bile acids may modulate CVD risk, and discuss potential bile-acid-based treatment strategies in relation to CVD.

Serum concentration of taurochenodeoxycholic acid predicts clinically significant portal hypertension

BACKGROUND & AIMS

Severity of portal hypertension is usually quantified by measuring the hepatic venous pressure gradient (HVPG). However, due to its invasiveness, alternative markers are being sought. Bile acids (BA), being synthesized, metabolized, and transported by the liver, seem to have the potential to serve as endogenous markers. The aim of the present study was to determine whether serum BA reflect the severity of portal hypertension.

METHODS

We correlated serum concentrations of individual BA with portal pressure (as HVPG) in an exploratory cohort of 21 cirrhotic patients with portal hypertension. The predictive potential of selected candidates was then confirmed in an independent validation cohort (n = 214). Additionally, nine previously published noninvasive markers were added to the stepwise logistic regression model to identify the most relevant ones, which were eventually used to create a prognostic index of portal hypertension.

RESULTS

Serum levels of taurochenodeoxycholic acid (TCDCA) significantly correlated with HVPG and showed a high potential to predict clinically significant portal hypertension (HVPG ≥ 10 mm Hg: AUROC = 0.97 ± 0.06). This was confirmed in the validation cohort (AUROC = 0.96 ± 0.01). The predictive index (constructed based on AST/ALT, spleen diameter, and TCDCA concentration) was able to distinguish clinically significant portal hypertension with 95% sensitivity and 76% specificity.

CONCLUSIONS

TCDCA seems to be a promising noninvasive marker of clinically significant portal hypertension. Its predictive potential may be further enhanced when it is combined with both the AST/ALT ratio and spleen diameter.

Empagliflozin ameliorates atherosclerosis via regulating the intestinal flora

BACKGROUND AND AIMS

Sodium-glucose cotransporter 2 inhibitor (SGLT2i) has been reported to attenuate atherosclerosis. Further, it has been suggested that intestinal flora influences atherosclerosis progression. Herein we aimed to investigate whether SGLT2i can alleviate atherosclerosis through intestinal flora.

METHODS

Six-week-old male ApoE^-/- mice fed a high-fat diet were gavaged either empagliflozin (SGLT2i group, n = 9) or saline (Ctrl group, n = 6) for 12 weeks. Feces were collected from both groups at the end of the experiment for fecal microbiota transplantation (FMT). Another 12 six-week-old male ApoE^-/- mice were fed a high-fat diet and received FMT with feces either from SGLT2i (FMT-SGLT2i group, n = 6) or from Ctrl (FMT-Ctrl group, n = 6) groups. Blood, tissue, and fecal samples were collected for subsequent analyses.

RESULTS

In comparison with Ctrl group, atherosclerosis was less severe in the SGLT2i group (p < 0.0001), and the richness of probiotic, such as f_Coriobacteriaceae, f_S24-7, f_Lachnospiraceae, and f_Adlercreutzia, was higher in feces. Besides, empagliflozin resulted in a significant reduction in the inflammatory response and altered intestinal flora metabolism. Interestingly, compared with FMT-Ctrl, FMT-SGLT2i also showed a reduction in atherosclerosis and systemic inflammatory response, as well as changes in the component of intestinal flora and pertinent metabolites similar to SGLT2i group.

CONCLUSIONS

Empagliflozin seems to mitigate atherosclerosis partly by regulating intestinal microbiota, and this anti-atherosclerotic effect can be transferred through intestinal flora transplantation.

7, 8-Dihydroxy-4-methyl coumarin alleviates cholestasis via activation of the Farnesoid X receptor in vitro and in vivo

Cholestasis is primarily caused by bile acid homeostasis dysregulation, resulting in retention, aggregation, and accumulation of the toxic cholate in the hepatocytes. Existing therapies for cholestasis are limited, demanding the urgent development of novel drugs. As a result, targeting FXR specifically promises a unique treatment strategy for cholestasis. The current study aims to evaluate the influence of 7, 8-dihydroxy-4-methyl coumarin (DMC) against alpha-naphthyl isothiocyanate (ANIT)-induced liver injury in mice. The "Computer-Aided Drug Design" (CADD) and molecular docking study anticipated that DMC would proficiently bind and activate the FXR. Accordingly, the hepatoprotective activity of DMC against ANIT-induced hepatotoxicity and cholestasis was investigated in ANIT-treated HepaRG cells and the ANIT-induced cholestatic mouse model. Outcomes indicated the protective effects of DMC against ANIT toxicity in HepaRG cells after 24 h of intervention and animals after seven days of treatment. DMC partially blocks ANIT-induced increases in serum markers of hepatocellular injury, liver and gall bladder enlargement, and hepatic necrosis. Western blotting revealed that DMC alleviates ANIT-induced hepatotoxicity and cholestasis via activating the FXR receptor and regulating CYP7A1, the enzyme responsible for bile acid synthesis. DMC exhibited protective activity against cholestasis through activating FXR, suggesting it might be a promising strategy for preventing and treating cholestatic liver disease.

The oral microbiome in the pathophysiology of cardiovascular disease

Despite advances in our understanding of the pathophysiology of many cardiovascular diseases (CVDs) and expansion of available therapies, the global burden of CVD-associated morbidity and mortality remains unacceptably high. Important gaps remain in our understanding of the mechanisms of CVD and determinants of disease progression. In the past decade, much research has been conducted on the human microbiome and its potential role in modulating CVD. With the advent of high-throughput technologies and multiomics analyses, the complex and dynamic relationship between the microbiota, their 'theatre of activity' and the host is gradually being elucidated. The relationship between the gut microbiome and CVD is well established. Much less is known about the role of disruption (dysbiosis) of the oral microbiome; however, interest in the field is growing, as is the body of literature from basic science and animal and human investigations. In this Review, we examine the link between the oral microbiome and CVD, specifically coronary artery disease, stroke, peripheral artery disease, heart failure, infective endocarditis and rheumatic heart disease. We discuss the various mechanisms by which oral dysbiosis contributes to CVD pathogenesis and potential strategies for prevention and treatment.

Treatment of Dyslipidemia through Targeted Therapy of Gut Microbiota

Dyslipidemia is a multifaceted condition with various genetic and environmental factors contributing to its pathogenesis. Further, this condition represents an important risk factor for its related sequalae including cardiovascular diseases (CVD) such as coronary artery disease (CAD) and stroke. Emerging evidence has shown that gut microbiota and their metabolites can worsen or protect against the development of dyslipidemia. Although there are currently numerous treatment modalities available including lifestyle modification and pharmacologic interventions, there has been promising research on dyslipidemia that involves the benefits of modulating gut microbiota in treating alterations in lipid metabolism. In this review, we examine the relationship between gut microbiota and dyslipidemia, the impact of gut microbiota metabolites on the development of dyslipidemia, and the current research on dietary interventions, prebiotics, probiotics, synbiotics and microbiota transplant as therapeutic modalities in prevention of cardiovascular disease. Overall, understanding the mechanisms by which gut microbiota and their metabolites affect dyslipidemia progression will help develop more precise therapeutic targets to optimize lipid metabolism.

Gut microbiome-mediated mechanisms for reducing cholesterol levels: implications for ameliorating cardiovascular disease

Cardiovascular disease (CVD) is a health problem worldwide, and elevated cholesterol levels are a key risk factor for the disease. Dysbiotic gut microbiota has been shown to be associated with CVD development. However, the beneficial effects of healthy microbiota in decreasing cholesterol levels have not been summarized. Herein, we begin by discussing the potential mechanisms by which the gut microbiota reduces cholesterol levels. We further sketch the application of probiotics from the genera Lactobacillus and Bifidobacterium in reducing cholesterol levels in clinical studies. Finally, we present the cholesterol-lowering function of beneficial commensal microbes, such as Akkermansia and Bacteroides spp., as these microbes have potential to be the next-generation probiotics (NGPs). The information reviewed in this paper will help people to understand how the gut microbiome might alter cholesterol metabolism and enable the development of NGPs to prevent and treat CVD.

Gut microbiome and metabolites, the future direction of diagnosis and treatment of atherosclerosis?

Over the past few decades, the treatment of atherosclerotic cardiovascular disease has mainly been through an LDL lowering strategy and treatments targeting other traditional risk factors for atherosclerosis, which has significantly reduced cardiovascular mortality. However, the overall benefit of targeting these risk factors has stagnated, and the discovery of new therapeutic targets for atherosclerosis remains a challenge. Accumulating evidence from clinical and animal experiments has revealed that the gut microbiome play a significant role in human health and disease, including cardiovascular diseases. The gut microbiome contribute to host health and disease through microbial composition and function. The gut microbiome function like an endocrine organ by generating bioactive metabolites that can impact atherosclerosis. In this review, we describe two gut microbial metabolites/pathways by which the gut affects atherosclerotic cardiovascular disease. On the one hand, we discuss the effects of trimethylamine oxide (TMAO), bile acids and aromatic amino acid metabolites on the development of atherosclerosis, and the protective effects of beneficial metabolites short chain amino acids and polyamines on atherosclerosis. On the other hand, we discuss novel therapeutic strategies for directly targeting gut microbial metabolites to improve cardiovascular outcomes. Reducing gut-derived TMAO levels and interfering with the bile acid receptor farnesoid X receptor (FXR) are new therapeutic strategies for atherosclerotic disease. Enzymes and receptors in gut microbiota metabolic pathways are potential new drug targets. We need solid insight into these underlying mechanisms to pave the way for therapeutic strategies targeting gut microbial metabolites/pathways for atherosclerotic cardiovascular disease.

Enterococcus faecium GEFA01 alleviates hypercholesterolemia by promoting reverse cholesterol transportation via modulating the gut microbiota-SCFA axis

This study aimed to identify cholesterol-lowering commensal strains from healthy lean individuals and to evaluate the cholesterol-lowering capacity of Enterococcus faecium GEFA01 in mice fed a high-cholesterol and high-fat diet. E. faecium GEFA01 was isolated from the feces of a healthy lean individual in a selective basal salt medium supplemented with cholesterol. E. faecium GEFA01 exhibited a cholesterol removal rate (CRR) of 46.13% by coprecipitation, assimilation, and degradation of cholesterol. Moreover, E. faecium GEFA01 significantly decreased the body weight of mice and the levels of serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), hepatic TC, triglycerides (TG), and LDL-C, and increased serum high-density lipoprotein cholesterol (HDL-C) levels in mice fed a high-cholesterol diet compared with the HCD group. We also observed that E. faecium GEFA01 significantly downregulated the gene expression of HMG-CoA reductase (Hmgcr), Srebp-1c, Fxr, Shp, and Fgf 15, upregulated the gene expression of low-density lipoprotein receptor (Ldlr), Abcg5/8, Abca1, cholesterol 7 alpha-hydroxylase (Cyp7a1), and Lxr in the liver of mice in relative to the HCD group, markedly increased the relative abundance of Lactobacillus, Akkermansia, Bifidobacterium, and Roseburia, and decreased the abundance of Helicobacter in the feces. Collectively, we confirmed that E. faecium GEFA01 exhibited cholesterol-lowering effects in mice fed a high-cholesterol diet, which was achieved through assimilation, coprecipitation, and degradation of cholesterol, and through modulation of the gut microbiota short-chain fatty acid (SCFA) axis that promoted reverse cholesterol transport and bile acid excretion. Our study demonstrated that E. faecium GEFA01 may be used as a probiotic candidate to lower cholesterol levels in the future.

Lipidomics combined with transcriptomic and mass spectrometry imaging analysis of the Asiatic toad (Bufo gargarizans) during metamorphosis and bufadienolide accumulation

Background

To adapt to life on land, Asiatic toads (Bufo gargarizans) must remodel their bodies and refine their chemical defenses in water. The full scope of the mechanisms underlying these processes has yet to be revealed. Bufadienolides (BDs) are chemical defense substances secreted by toads when they are in danger, and they have high medicinal value in treating heart failure, cancer, and hepatitis. However, the artificial breeding of toads to increase BDs has been unsuccessful due to the high mortality of toad larvae during metamorphosis.

Method

Toad larvae at different growth stages were selected to study the changes in the metamorphosis process under the same growth conditions. The differences of tadpoles were explored, including body remodeling, energy metabolism, synthesis and regulation of BDs, through lipidomic technology, transcriptomic technology, and mass spectrometry imaging technology during metamorphosis.

Results

During metamorphosis, tadpoles underwent significant changes in lipid metabolism due to body remodeling to adapt to terrestrial life, which involved ketosis, lipogenesis, cholesterol metabolism, and fatty acid oxidation. The accumulation trend of BDs was observed. “Pentose phosphate pathway” and “Aromatase activity” may be the critical pathway and GO term in BD synthesis, involving 16 genes predominantly expressed in the liver. The involved genes were mainly expressed in the liver, consistent with the synthetic site observed by mass spectrometry imaging.

Conclusion

Together, our findings presented the changes in the toad larvae during metamorphosis and highlighted the accumulation process of BDs as well as the regulatory pathways and synthetic site, providing research and theoretical basis for future development of the toad resources.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-022-00676-7.

The role of FXR and TGR5 in reversing and preventing progression of Western diet-induced hepatic steatosis, inflammation, and fibrosis in mice

Nonalcoholic steatohepatitis (NASH) is the most common chronic liver disease in the US, partly due to the increasing incidence of metabolic syndrome, obesity, and type 2 diabetes. The roles of bile acids and their receptors, such as the nuclear receptor farnesoid X receptor (FXR) and the G protein-coupled receptor TGR5, on the development of NASH are not fully clear. C57BL/6J male mice fed a Western diet (WD) develop characteristics of NASH, allowing determination of the effects of FXR and TGR5 agonists on this disease. Here we show that the FXR-TGR5 dual agonist INT-767 prevents progression of WD-induced hepatic steatosis, inflammation, and fibrosis, as determined by histological and biochemical assays and novel label-free microscopy imaging techniques, including third harmonic generation, second harmonic generation, and fluorescence lifetime imaging microscopy. Furthermore, we show INT-767 decreases liver fatty acid synthesis and fatty acid and cholesterol uptake, as well as liver inflammation. INT-767 markedly changed bile acid composition in the liver and intestine, leading to notable decreases in the hydrophobicity index of bile acids, known to limit cholesterol and lipid absorption. In addition, INT-767 upregulated expression of liver p-AMPK, SIRT1, PGC-1α, and SIRT3, which are master regulators of mitochondrial function. Finally, we found INT-767 treatment reduced WD-induced dysbiosis of gut microbiota. Interestingly, the effects of INT-767 in attenuating NASH were absent in FXR-null mice, but still present in TGR5-null mice. Our findings support treatment and prevention protocols with the dual FXR-TGR5 agonist INT-767 arrest progression of WD-induced NASH in mice mediated by FXR-dependent, TGR5-independent mechanisms.

Bile acid metabolism and signaling, the microbiota, and metabolic disease

The diversity, composition, and function of the bacterial community inhabiting the human gastrointestinal tract contributes to host health through its role in producing energy or signaling molecules that regulate metabolic and immunologic functions. Bile acids are potent metabolic and immune signaling molecules synthesized from cholesterol in the liver and then transported to the intestine where they can undergo metabolism by gut bacteria. The combination of host- and microbiota-derived enzymatic activities contribute to the composition of the bile acid pool and thus there can be great diversity in bile acid composition that depends in part on the differences in the gut bacteria species. Bile acids can profoundly impact host metabolic and immunological functions by activating different bile acid receptors to regulate signaling pathways that control a broad range of complex symbiotic metabolic networks, including glucose, lipid, steroid and xenobiotic metabolism, and modulation of energy homeostasis. Disruption of bile acid signaling due to perturbation of the gut microbiota or dysregulation of the gut microbiota-host interaction is associated with the pathogenesis and progression of metabolic disorders. The metabolic and immunological roles of bile acids in human health have led to novel therapeutic approaches to manipulate the bile acid pool size, composition, and function by targeting one or multiple components of the microbiota-bile acid-bile acid receptor axis.

Lactobacilli and Bifidobacterium as anti-atherosclerotic agents

Atherosclerosis is the thickening or hardening of the arteries which is caused by a buildup of atheromatous plaque in the inner lining of an artery. Hypercholesterolemia, inflammation, oxidative stress, and trimethylamine N-oxide (TMAO) are important risk factors for atherosclerosis. Therefore, this study aimed to review the anti-atherosclerotic effects of Lactobacilli and Bifidobacterium via improving lipid profile and reducing the effects of oxidative stress, inflammation, and TMAO. To prepare the present review, several databases such as Scopus, PubMed, and Google Scholar were searched, and relevant articles from 1990 until 2022 were selected and reviewed. The present review showed that Lactobacilli and Bifidobacterium reduce the risk of atherosclerosis in both in vitro and in vivo studies by breaking down or altering cholesterol metabolism with the help of their by-products and by reducing inflammation and oxidative stress and TMAO. Consumption of Lactobacilli and Bifidobacterium can be useful in prevention of atherosclerosis.

Theacrine ameliorates experimental liver fibrosis in rats by lowering cholesterol storage via activation of the Sirtuin 3-farnesoid X receptor signaling pathway

Formulations against liver fibrosis (LF) mitigate the progression of hepatitis to cirrhosis. However, notable toxicity of the currently available anti-LF drugs limits their long-term use. In the study, we aimed to investigate the anti-LF effects of theacrine, a purine alkaloid without obvious toxicity, on high-fat diet-, alcohol-, and carbon tetrachloride-induced LF in rats. The results indicated that 10 and 20 mg/kg of theacrine ameliorated hepatic fibrosis, steatosis, and inflammation in LF rats. Mechanistically, theacrine reduced hepatic stellate cell (HSC)-related α-smooth muscle actin expression, and decreased cholesterol accumulation, followed by decreased expression of transforming growth factor-β1, interleukin (IL)-1β, and tumor necrosis factor (TNF)-α. In addition, theacrine upregulated the phosphorylation of AMP-activated protein kinase, accompanied by decreased expression of β-catenin and stearoyl-CoA desaturase 1, and increased the expression of sirtuin 3 (SIRT3). Further investigation revealed that the theacrine-mediated decrease in cholesterol was independent of cholesterol synthesis or low-density lipoprotein (LDL) uptake in hyperlipidemia mice. However, theacrine activated farnesoid X receptor (FXR), a β-catenin conjugated protein, accompanied with decreased expression of cholesterol 7α-hydroxylase and sterol 12α-hydroxylase. In conclusion, theacrine alleviated experimental LF in rats by lowering cholesterol storage and decreasing cholesterol-related HSC activation. A plausible mechanism of theacrine on cholesterol metabolism may involve activation of SIRT3-FXR signaling pathway followed by decreased intestinal cholesterol absorption.

Recent advances on FXR-targeting therapeutics

The bile acid receptor FXR has emerged as a bona fide drug target for chronic cholestatic and metabolic liver diseases, ahead of all non-alcoholic fatty liver disease (NAFLD). FXR is highly expressed in the liver and intestine and activation at both sites differentially contributes to its desired metabolic effects. Unrestricted FXR activation, however, also comes along with undesired effects such as a pro-atherogenic lipid profile, pruritus and hepatocellular toxicity under certain conditions. Several pre-clinical studies have confirmed the potency of FXR activation for cholestatic and metabolic liver diseases, but overall it remains still open whether selective activation of intestinal FXR is advantageous over pan-FXR activation and whether restricted or modulated FXR activation can limit some of the side effects. Even more, FXR antagonist also bear the potential as intestinal-selective drugs in NAFLD models. In this review we will discuss the molecular prerequisites for FXR activation, pan-FXR activation and intestinal FXR in/activation from a therapeutic point of view, different steroidal and non-steroidal FXR agonists, ways to restrict FXR activation and finally what we have learned from pre-clinical models and clinical trials with different FXR therapeutics.

A Bibliometric Analysis of Research on the Links Between Gut Microbiota and Atherosclerosis

Background

Emerging evidence has linked gut microbiota (GM) and its related metabolites to atherosclerosis (AS). This study aimed to analyze the evolution of GM in AS in the past decades, and provide valuable insights in this field.

Methods

Web of Science Core Collection (WoSCC) was applied to retrieve the publications related to GM in AS from their inception until 2 December 2021, and the data was analyzed in Microsoft Excel, Scimago Graphica, CiteSpace, and VOSviewer.

Results

In total, 560 documents were extracted from the WoSCC databases. The publications have shown rapid growth since 2008. China and Cleveland Clin were the most prolific country and institution, respectively. The journal with the most publications is Nutrients, and Nature was the most co-cited journal. Among 3556 related authors, Hazen, Stanley L., Tang, W. H. Wilson, and Wang, Zeneng were the top 3 contributing authors in this field. Aside from “gut microbiota,” “atherosclerosis,” the terms “TMAO,” “metabolite,” “obesity,” and “phosphatidylcholine” were frequently occurred in the abstract and title of articles. Burst detection of keywords indicated that “metabolic syndrome,” “acid,” and “bile acid” were hot topics in recent years. According to the co-citation analysis of references, the research focus in this area has changed over time, and recent researches focus on choline, hypertension, butyrate, and berberine.

Conclusion

Our study showed that the researches of GM in AS have been flourishing, and the content themes were constantly deepened. Human GM is critical to atherosclerotic diseases, and this hot topic is still worthy of more focus in the future.

Alisol B 23-acetate adjusts bile acid metabolisim via hepatic FXR-BSEP signaling activation to alleviate atherosclerosis

BACKGROUND

Postmenopausal women have a high incidence of atherosclerosis. Phytosterols have been shown to have cholesterol-lowering properties. Alisa B 23-acetate (AB23A) is a biologically active plant sterol isolated from Chinese herbal medicine Alisma. However, the atherosclerosis effect of AB23A after menopause and its possible mechanism have not been reported yet.

PURPOSE

To explore whether AB23A can prevent atherosclerosis by regulating farnesoid X receptor and subsequently increasing fecal bile acid and cholesterol excretion to reduce plasma cholesterol levels.

METHODS

Aortic samples from premenopausal and postmenopausal women with ascending aortic arteriosclerosis were analyzed, and bilateral ovariectomized (OVX) female LDLR^-/- mice and free fatty acid (FFA)-treated L02 cells were used to analyze the effect of AB23A supplementation therapy.

RESULTS

AB23A increased fecal cholesterol and bile acids (BAs) excretion dependent on activation of hepatic farnesoid X receptor (FXR) in ovariectomized mice. AB23A inhibited hepatic cholesterol 7α-hydroxylase (CYP7A1) and sterol 12α-hydroxylase (CYP8B1) via inducing small heterodimer partner (SHP) expression. On the other hand, AB23A increased the level of hepatic chenodeoxycholic acid (CDCA), and activated the hepatic BSEP signaling. The activation of hepatic FXR-BSEP signaling by AB23A in ovariectomized mice was accompanied by the reduction of liver cholesterol, hepatic lipolysis, and bile acids efflux, and reduced the damage of atherosclerosis. In vitro, AB23A fixed abnormal lipid metabolism in L02 cells and increased the expression of FXR, BSEP and SHP. Moreover, the inhibition and silencing of FXR canceled the regulation of BSEP by AB23A in L02 cells.

CONCLUSION

Our results shed light into the mechanisms behind the cholesterol-lowering of AB23A, and increasing FXR-BSEP signaling by AB23A may be a potential postmenopausal atherosclerosis therapy.

Nutritional and Chemical Composition of Sargassum zhangii and the Physical and Chemical Characterization, Binding Bile Acid, and Cholesterol-Lowering Activity in HepG2 Cells of Its Fucoidans

Fucoidan is a marine sulfated polysaccharide that is rich in Sargassum and has a wide range of biological activities. In this study, the chemical composition and bile acid binding ability of six crude fucoidans were compared, the nutrition and chemical composition of Sargassum zhangii were analyzed, and fucoidan from Sargassum zhangii was extracted and purified. The purified fractions (ZF1, ZF2, and ZF3) were analyzed by physicochemical characterization, and the ability of binding bile acid and cholesterol lowering in HepG2 cells were evaluated. The results showed that the contents of sulfate in crude fucoidan from Sargassum Zhangii (ZF) was as high as13.63%. Its ability of binding bile acid was better than other five crude fucoidans. Sargassum zhangii was a kind of brown seaweed with high carbohydrate, and low fat and rich in minerals. The sulfate content of ZF1, ZF2, and ZF3 was 3.29%, 19.39%, and 18.89% respectively, and the molecular weight (Mw) was 4.026 × 10⁵, 2.893 × 10⁵, and 3.368 × 10⁵, respectively. Three fucoidans all contained the characteristic absorption bands of polysaccharides and sulfate groups and were rich in fucose. Three fucoidans can bind to bile acid, and ZF2 showed the best binding capability. In vitro experiments showed that ZF1, ZF2, and ZF3 could reduce intracellular total cholesterol (TC) content in HepG2 cells without affecting their viability. ZF2 showed the best ability to reduce TC.

Survival Benefit of Statin with Anti-Angiogenesis Efficacy in Lung Cancer-Associated Pleural Fluid through FXR Modulation

Simple Summary

Our previous works showed that pleural fluid from lung cancer significantly induced endothelial proliferation, migration, and angiogenesis. Since endothelial metabolism was a key step in angiogenesis, we investigated the role of bile acid signaling and FXR expression in pleural angiogenesis. Elevated bile acid levels in lung-cancer-associated pleural fluid (LCPF) were characterized with positive FXR staining in pleural microvessels. We then confirmed the inhibitory effect of an FXR antagonist on LCPF-induced endothelial migration and angiogenesis. Due to the elevated protein expression in the cholesterol metabolism caused by LCPF, lipid-lowering agents with the efficacy needed to counteract LCPF-regulated angiogenesis were evaluated. Statin showed the potent efficacy needed to suppress LCPF-induced endothelial proliferation, migration, and angiogenesis through FXR inhibition. Following that, Kaplan–Meier analysis showed the survival benefit of statin exposure in patients with lung adenocarcinoma with LCPF. Our results suggest that targeting endothelial FXR signaling with statin treatment could ameliorate the angiogenesis activity of LCPF.

Abstract

Lung cancer-related pleural fluid (LCPF) presents as a common complication with limited treatment. Beyond its function in lipid digestion, bile acid was identified as a potent carcinogen to stimulate tumor proliferation. Previous research indicated a correlation between serum bile acid levels and the risk of developing several gastrointestinal cancers. Our study identified elevated bile acid levels in LCPF and increased farnesoid X receptor (FXR) expression as bile acid nuclear receptors in pleural microvessels of lung adenocarcinoma. Additionally, LCPF stimulated the expression of proteins involved in bile acid synthesis and cholesterol metabolism in HUVECs including CYP7A1, StAR, HMGCR, and SREBP2. LCPF-induced endothelial motility and angiogenesis were counteracted by using β-muricholic acid as an FXR antagonist. Moreover, we investigated the efficacy of cholesterol-lowering medications, such as cholestyramine, fenofibrate, and atorvastatin, in regulating LCPF-regulated angiogenesis. Along with suppressing endothelial proliferation and angiogenesis, atorvastatin treatment reversed cholesterol accumulation and endothelial junction disruption caused by LCPF. Statin treatment inhibited LCPF-induced endothelial FXR expression as well as the downstream proteins RXR and SHP. Based on the positive findings of suppressing endothelial angiogenesis, our group further incorporated the effect of statin on clinical patients complicated with LCPF. A Kaplan–Meier analysis revealed the clinical benefit of statin exposure in patients with lung adenocarcinoma with LCPF. Conclusively, our study demonstrated the ability of statin to alleviate LCPF-induced angiogenesis in patients with LCPF via FXR modulation.

Enterohepatic and non-canonical roles of farnesoid X receptor in controlling lipid and glucose metabolism

Farnesoid X receptor (FXR) is a nuclear receptor that transcriptionally regulates bile acid homeostasis along with nutrient metabolism. In addition to the gastrointestinal (GI) tract, FXR expression has been widely noted in kidney, adrenal gland, pancreas, adipose, skeletal muscle, heart, and brain. Except for the liver and gut, the relevance of FXR signaling in metabolism in other tissues remains poorly understood. This review examines the classical and non-canonical tissue-specific roles of FXR in regulating, lipids, and glucose homeostasis under normal and diseased states. FXR activation has been reported to be protective against cholestasis, nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH), type 2 diabetes, cardiovascular and kidney diseases. Several ongoing clinical trials are investigating FXR ligands as a therapeutic target for primary biliary cholangitis (PBC) and NASH, which substantiate the significance of FXR signaling in modulating metabolic processes. This review highlights that FXR ligands, albeit an attractive therapeutic target for treating metabolic diseases, tissue-specific modulation of FXR may be the key to overcoming some of the adverse clinical effects.

Obeticholic acid inhibits hepatic fatty acid uptake independent of FXR in mouse

OBJECTIVE

Obeticholic acid (OCA), a farnesoid X receptor (FXR) agonist, is believed to alleviate nonalcoholic fatty liver disease (NAFLD) by decreasing hepatic lipogenesis in an FXR-dependent manner. Here, we revealed a novel mechanism by which OCA improves NAFLD by affecting hepatic long-chain fatty acids (LCFAs) uptake.

METHODS

Stably transfected HEK-293 cells expressing fatty acid transport protein 5 (FATP5) were established to examine fatty acid uptake; FXR^-/-, human (h) FATP5, and FXR^-/-/hFATP5 mouse models were incorporated to explore the effects of OCA on FATP5 ex vivo and in vivo.

RESULTS

OCA inhibited hFATP5 (IC₅₀ =0.07 μM) more than murine (m) FATP5 (IC₅₀ =1.04 μM) as measured by LCFAs uptake in FATP5 expressing HEK-293. OCA also inhibited LCFA uptake in primary hepatocytes from hFATP5 mice, FXR^-/-/hFATP5 mice more than that from FXR^-/- mice, ex vivo. Moreover, OCA inhibited LCFAs uptake by livers in hFATP5 mice and FXR^-/-/hFATP5 mice, but not in FXR^-/- mice, in vivo. Long-term administration of 0.04% OCA markedly reduced hepatic triglyceride (TG) accumulation in hFATP5 mice and FXR^-/-/hFATP5 mice by 63% and 53%, respectively, but not in FXR^-/- mice.

CONCLUSIONS

OCA ameliorated high-fat diet-induced NAFLD independent of FXR by inhibiting hepatic hFATP5-mediated LCFAs uptake. This suggests that the therapeutic effects of OCA on NAFLD in vivo are mediated by a novel, hFATP5 dependent mechanism.

Obeticholic Acid Induces Hepatoxicity Via FXR in the NAFLD Mice

Objective: Obeticholic acid (OCA), a potent farnesoid X receptor (FXR) agonist, is a promising drug for nonalcoholic fatty liver disease (NAFLD); however, it can cause liver injury, especially at high doses. Here, we investigated the role of FXR in the high-dose OCA-induced hepatoxicity in the condition of the NAFLD mouse model.

Methods: Wild-type (WT) mice and FXR^−/− mice were administered with over-dose OCA (0.40%) and high-dose OCA (0.16%), in a high-fat diet. RNA-seq on liver samples of mice fed with high-dose OCA was performed to dig out the prominent biological events contributing to hepatic fibrosis.

Results: Over-dose OCA induced liver injury and shortened survival in WT mice, but not FXR^−/− mice. High-dose OCA caused hepatic stellate cell activation and liver fibrosis in the presence of FXR. Furthermore, high-dose OCA induced cholesterol accumulation in livers via the upregulation of genes involved in cholesterol acquisition and downregulation of genes regulating cholesterol degradation in liver, leading to the production of interleukin -1β and an FXR-mediated inflammatory response.

Conclusion: The high-dose OCA induced FXR-dependent hepatic injury via cholesterol accumulation and interleukin -1β pathway in the NAFLD mice.

Bile acid coordinates microbiota homeostasis and systemic immunometabolism in cardiometabolic diseases

Cardiometabolic disease (CMD), characterized with metabolic disorder triggered cardiovascular events, is a leading cause of death and disability. Metabolic disorders trigger chronic low-grade inflammation, and actually, a new concept of metaflammation has been proposed to define the state of metabolism connected with immunological adaptations. Amongst the continuously increased list of systemic metabolites in regulation of immune system, bile acids (BAs) represent a distinct class of metabolites implicated in the whole process of CMD development because of its multifaceted roles in shaping systemic immunometabolism. BAs can directly modulate the immune system by either boosting or inhibiting inflammatory responses via diverse mechanisms. Moreover, BAs are key determinants in maintaining the dynamic communication between the host and microbiota. Importantly, BAs via targeting Farnesoid X receptor (FXR) and diverse other nuclear receptors play key roles in regulating metabolic homeostasis of lipids, glucose, and amino acids. Moreover, BAs axis per se is susceptible to inflammatory and metabolic intervention, and thereby BAs axis may constitute a reciprocal regulatory loop in metaflammation. We thus propose that BAs axis represents a core coordinator in integrating systemic immunometabolism implicated in the process of CMD. We provide an updated summary and an intensive discussion about how BAs shape both the innate and adaptive immune system, and how BAs axis function as a core coordinator in integrating metabolic disorder to chronic inflammation in conditions of CMD.