Bile acids: regulation of synthesis

Gut microbiota regulates hepatic ketogenesis and lipid accumulation in ketogenic diet-induced hyperketonemia by disrupting bile acid metabolism

The ketogenic diet (KD) induces prolonged hyperketonemia, characterized by elevated circulating level of β-hydroxybutyrate. However, the KD can negatively affect host metabolic health by altering the gut microbial community. Despite this, the regulatory effect of the gut microbiota on hepatic ketogenesis and triacylglycerol (TAG) accumulation during a KD remains poorly understood. Here, we hypothesized that the commensal bacterium regulates hepatic lipid metabolism in association with KD-induced hyperketonemia. The KD disrupts the remodeling of the gut microbiota following antibiotic-induced depletion. The capacity for ketogenesis and the severity of TAG accumulation in the liver closely correlated with changes in the gut microbial composition and the up-regulation of hepatic farnesoid X receptor (FXR), peroxisome proliferator-activated receptor alpha (PPARα), and diacylglycerol O-acyltransferase 2 (DGAT2), which were modulated by bile acid metabolism through the gut-liver axis. The commensal bacterium Clostridium perfringens type A is particularly implicated in prolonged hyperketonemia, exacerbating hepatic ketogenesis and steatosis by disrupting secondary bile acid metabolism. The increased conversion of deoxycholic acid to 12-ketolithocholic acid represents a critical microbial pathway during C. perfringens colonization. These findings illuminate the adverse effects of the gut microbiota on hepatic adaptation to a KD and highlight the regulatory role of C. perfringens in ketonic states.

Dysbiosis of the gut micro-flora aggravates symptoms and accelerates disease progression in MASLD-IBD Co-morbid mice through host-microbial metabolic imbalance

Studies have shown that dysregulation of intestinal microbial structure and co-metabolic imbalance caused by diet and other factors play important role in MASLD and IBD. However, it is unclear how host-microbial interactions differ in the two diseases, and what potential impact they have on accelerating disease progression. Our study aims to find the disease characteristics in MASLD, IBD and their complication from the perspective of host-microbial metabolism. In our study, mouse models of MASLD, IBD, and MASLD-IBD induced by high-fat diet and dextran sulfate sodium. Detecting the pathological changes of colon and liver. Using 16s rRNA to screen out specific micro-flora, and UPLC-MS to monitor the changes of metabolites in feces. The micro-flora-metabolite co-expression network was constructed by Cytoscape software. The result showed that MASLD-IBD mice aggravate intestinal barrier damage, hepatic steatosis and fibrosis, immune inflammation and other pathological changes. In MASLD-IBD mice, the structural change of gut micro-flora is similar to IBD mice, which significantly reduced the abundance of Actinobacteriota, Desulfobacterota while increasing the abundance of Proteobacteria, and the metabolic disorder include nine metabolic pathways, such as tryptophan, bile acids and short-chain fatty acids, is similar to MASLD mice. Their co-expression network indicates that different specific micro-flora are closely related to the metabolic disorder and disease symptoms of MASLD-IBD mice. Analyzing the relationship between intestinal microbial dysregulation and hoetic co-metabolic imbalance is helpful to understand the mechanism of MASLD and IBD comorbidity, which suggesting that combined liver-gut therapy may be a new method for the treatment of MASLD-IBD complication.

Reveal the mechanism of hepatic oxidative stress in mice induced by photo-oxidation milk using multi-omics analysis techniques

INTRODUCTION

Photo-oxidation is recognized as a contributor to the deterioration of milk quality, posing potential safety hazards to human health. However, there has been limited investigation into the impact of consuming photo-oxidized milk on health.

OBJECTIVES

This study employs multi-omics analysis techniques to elucidate the mechanisms by which photo-oxidized milk induces oxidative stress in the liver.

METHODS

Mouse model was used to determine the effect of the gavage administration of milk with varying degrees of photo-oxidation on the mouse liver. The damage degree was established by measuring serum markers indicative of oxidative stress, and with a subsequent histopathological examination of liver tissues. In addition, comprehensive metabolome, lipidome, and transcriptome analyses were conducted to elucidate the underlying molecular mechanisms of hepatic damage caused by photo-oxidized milk.

RESULTS

A significant elevation in the oxidative stress levels and the presence of hepatocellular swelling and inflammation subsequent to the gavage administration of photo-oxidized milk to mice. Significant alterations in the levels of metabolites such as lumichrome, all-trans-retinal, L-valine, phosphatidylglycerol, and phosphatidylcholine within the hepatic tissue of mice. Moreover, photo-oxidized milk exerted a pronounced detrimental impact on the glycerophospholipid metabolism of mice liver. The peroxisome proliferator-activated receptors (PPAR) signaling pathway enrichment appreciated in the animals that consumed photo-oxidized milk further supports the substantial negative influence of photo-oxidized milk on hepatic lipid metabolism. Gene set enrichment and interaction analyses revealed that photo-oxidized milk inhibited the cytochrome P450 pathway in mice, while also affecting other pathways associated with cellular stress response and lipid biosynthesis.

CONCLUSION

This comprehensive study provides significant evidence regarding the potential health risks associated with photo-oxidized milk, particularly in terms of hepatic oxidative damage. It establishes a scientific foundation for assessing the safety of such milk and ensuring the quality of dairy products.

Changes in the FXR-cistrome and alterations in bile acid physiology in Wilson disease

BACKGROUND

Wilson disease (WD) is an autosomal recessive disorder that results in excessive hepatic copper, causing hepatic steatosis, inflammation, fibrosis, cirrhosis, and liver failure. Previous studies have revealed dysregulation of many farnesoid X receptor (FXR) metabolic target genes in WD, including the bile salt exporter pump, the major determinant of bile flow.

METHODS

We tested the hypothesis that the FXR-cistrome is decreased in Atp7b-/- mice in accord with dysregulated bile acid homeostasis.

RESULTS

FXR binding within Atp7b-/- mouse livers displayed surprising complexity: FXR binding was increased in distal intergenic regions but decreased in promoter regions in Atp7b-/- versus wild-type mice. Decreased FXR occupancy in Atp7b-/- versus wild-type mice was observed in hepatocyte metabolic and bile acid homeostasis pathways, while enrichment of FXR binding was observed in pathways associated with cellular damage outside of hepatocytes. Indeed, disparate FXR occupancy was identified in parenchymal and non-parenchymal marker genes in a manner that suggests decreased FXR activity in parenchymal cells, as expected, and increased FXR activity in non-parenchymal cells. Consistent with altered FXR function, serum and liver bile acid concentrations were higher in Atp7b-/- mice than in wild-type mice. Comparison of bile acid profiles in the serum of WD patients with "liver," "neurological," or "mixed" disease versus healthy controls also revealed increases in specific bile acids in WD-liver versus healthy controls.

CONCLUSIONS

We identified novel FXR-occupancy across the genome that varied in parenchymal and non-parenchymal cells, demonstrating complex FXR regulation of metabolic and hepatocellular stress pathways in Atp7b-/- mice. Dynamic changes in FXR activity support our novel finding of altered bile acid metabolism in Atp7b-/- mice and WD patients.

Allo-lithocholic acid, a microbiome derived secondary bile acid, attenuates liver fibrosis

Secondary bile acids, lithocholic acid and deoxycholic acid (LCA and DCA), are dehydroxylated derivatives of primary bile acids. However, in addition to LCA and DCA the intestinal microbiota produced a variety of poorly characterized metabolites. Allo-LCA, a LCA metabolite, acts as a dual GPBAR1 agonist and RORγt inverse agonist and modulates intestinal immunity, although is not yet known whether allo-LCA exerts regulatory functions outside the intestine. In the present study we have therefore investigated whether administration of allo-LCA, 10 mg/kg/day, to mice administered a high fat/high fructose diet (HFD-F) and carbon tetrachloride (Ccl4), a model for metabolic dysfunction-associated steatohepatitis (MASH), protects from development of liver damage. In vitro allo-LCA functions as GPBAR1 agonist and RORγt inverse agonist and prevents macrophages M1 polarization and Th17 polarization of CD4 cells. In vivo studies, while exposure to a HFD-F/Ccl4 promoted insulin resistance and development of a pro-atherogenic lipid profile and liver steatosis and fibrosis, allo-LCA reversed this pattern by improving insulin sensitivity and liver lipid accumulation. The liver transcriptomic profile demonstrated that allo-LCA reversed the dysregulation of multiple pathways associated with immunological, inflammatory and metabolic signaling. Allo-LCA also restored bile acid homeostasis, reversing HFD/Ccl4-induced shifts in bile acid pool composition and restored adipose tissue histopathology and function by reducing the expression of leptin and resistin, two pro-inflammatory adipokines, and restored a healthier composition of the intestinal microbiota. In conclusion, present results expand on the characterization of entero-hepatic signaling and suggest that allo-LCA, a microbial metabolite, might have therapeutic potential in liver diseases.

Intermittent fasting and metabolic dysfunction-associated steatotic liver disease: the potential role of the gut-liver axis

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a growing public health concern linked to the increasing prevalence of metabolic syndrome, including obesity and type 2 diabetes (T2D). MASLD remains a significant clinical challenge due to the absence of effective therapeutic interventions. Intermittent fasting (IF) has emerged as a promising non-pharmacological strategy for managing MASLD. Although the exact mechanisms underpinning the possible beneficial effects of IF on MASLD are not yet fully elucidated, the gut microbiota and its metabolic byproducts are increasingly recognized as potential mediators of these effects. The gut-liver axis may act as an important conduit through which IF exerts its beneficial influence on hepatic function. This review comprehensively examines the impact of various IF protocols on gut microbiota composition, investigating the resultant alterations in microbial diversity and metabolomic profiles, and their potential implications for liver health and the improvement of MASLD.

Conjugated bile acids are elevated in severe calcific aortic valve stenosis

INTRODUCTION

Calcific aortic valve stenosis (CAVS) is a disease associated with significant morbidity and mortality in the aging population. Recently, bile acids have been shown to play a significant role in many disease processes, and untargeted metabolomic analyses of CAVS patient valves has shown a disrupted bile acid pathway.

AIM

We aimed to understand the changes in human valvular bile acids in relation to CAVS severity.

METHODS

A total of 100 human aortic valves were collected from patients undergoing aortic valve replacement surgery. Bile acids were quantified by ultrahigh performance liquid chromatography coupled to tandem mass spectrometry.

RESULTS

Patients with mild aortic stenosis (AS) showed a distinct valvular bile acid composition compared to moderate and severe AS groups, with five bile acids being significantly elevated in patients with moderate and severe AS. These included norcholic, nordeoxycholic, glycodeoxycholic, glycocholic and taurodeoxycholic acid. When classified by calcification score, five species were significantly different between mild and severe AS groups; four bile acids were similar when stratified based on AS severity. Using k means clustering we were able to distinguish valve severity by their bile acid composition. Grouping bile acids by conjugation and by primary versus secondary revealed that conjugated primary and secondary bile acids were significantly increased in stenotic valves compared to the mild AS group.

CONCLUSION

Conjugated bile acids are significantly elevated in the valvular tissue of patients with severe calcific aortic stenosis. These findings suggest a potential link between liverand gut microbiome physiologyand bile acid pathways in contributing to the pathophysiology of valvular stenosis.

A simple surrogate approach for the quantitation of C4 (7α-hydroxy-4-cholesten-3-one) in human serum via LC-MS/MS and its application in a clinical study

We present a validated LC-MS/MS assay for the quantitation of 7α-hydroxy-4-cholesten-3-one (C4), a key intermediate in the bile acid synthesis pathway from cholesterol, in human serum. A surrogate matrix approach was employed to overcome the challenges posed by the endogenous C4 levels in the biological matrix. Human serum samples were spiked with stable isotope labeled internal standard (SIL-IS), processed using supported liquid extraction (SLE), and analyzed by LC-MS/MS. Parallelism was successfully demonstrated between human serum (authentic matrix) and 5 % bovine serum albumin in phosphate buffered saline containing 0.1 % tween 20 (5 % BSA in PBST) (surrogate matrix). The assay's linear analytical range was established from 0.200 to 200 ng/mL. This validated LC-MS/MS method exhibited excellent accuracy and precision. The overall accuracy was between 97.9 % and 101 % with %CV less than 4.0 % for C4 in human serum. C4 was found to be stable in human serum for up to 24.7 h at room temperature, up to 34 days when stored at -25 °C or - 80 °C, and after five freeze/thaw cycles. The assay has been successfully applied to human serum samples to support a clinical study.

Bile Acids Modulate Hepatic Glycolipid Metabolism via the Microbiota-Gut-Liver Axis in Lambs

BACKGROUND

Bile acids are essential molecules that facilitate lipid emulsification and function as signaling molecules mediating host-microbiota interactions. They shape the gut microbial structure and function, playing a critical role in metabolic regulation via the gut-liver axis.

OBJECTIVES

This study aimed to investigate the effects of exogenous bile acids, primarily hyocholic acid (HCA), on the microbiota-gut-liver metabolism in male Tan-lambs fed a high-grain diet.

METHOD

Thirty six-month-old male Tan lambs (Ovis aries) were randomly allocated into either a control (CON) group or an HCA-supplemented group (n = 15 per group). The trial lasted 84 days, including a 14-day adaptation period. On day 70, six lambs from each group were randomly selected for slaughter. Rumen and ileal contents were collected for microbial profiling via 16S rRNA sequencing, and liver tissue samples were harvested for transcriptomic and metabolomic analyses.

RESULTS

The HCA intervention significant altered the composition and structure of ruminal and ileal bacteria. Notable increases were observed in Turicibacter (linear discriminant analysis (LDA) score = 2.48; P < 0.05) and Muribaculaceae (LDA score = 3.75; P < 0.05) in the rumen, and Eubacterium fissicatena group (LDA score = 2.50; P < 0.05) in the ileum. Key hepatic genes and metabolites targeted by HCA were identified, including ENPP3, RFK, Ifi203, LIPG, CYP1A1, CYP4A11, nordeoxycholic acid (log-fold change = 6.30, P < 0.005), α-muricholic acid (log-fold change = 5.60, P < 0.001), β-muricholic acid (log-fold change = 5.60, P < 0.001).

CONCLUSIONS

Exogenous bile acids regulate the microbiota-gut-liver axis, influencing hepatic glycolipid metabolism in sheep. Specifically, nordeoxycholic acid, demonstrates potential as a dietary intervention to promote metabolic homeostasis in ruminants. These findings highlight the potential of HCA and norDCA as functional feed additives or prebiotic agents for improving metabolic health in ruminants and potentially other species.

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

BACKGROUND

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

AIM OF REVIEW

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

KEY SCIENTIFIC CONCEPTS OF REVIEW

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

Cholestasis in Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) is a leading cause of liver-related morbidity and mortality. ALD covers a spectrum of diseases, ranging from mild and reversible hepatic steatosis to the development of fibrosis, cirrhosis, and alcohol-associated hepatitis (AH). AH is marked by a rapid onset of jaundice and elevated serum levels of aspartate aminotransferase in individuals with heavy alcohol use. It can progress to acute-on-chronic liver failure, with a mortality rate of approximately 30% within the first month. Unfortunately, treatment options for AH are still limited. Cholestasis refers to an impairment in bile formation or flow, leading to clinical symptoms, such as fatigue, pruritus, and jaundice. Cholestasis and biliary dysfunction are commonly seen in patients with AH and can significantly worsen the prognosis. However, the mechanisms and roles of cholestasis in ALD are not yet fully understood. In this review, we will summarize recent findings and explore the potential roles and mechanisms of cholestasis in the progression of ALD.

Short-chain fatty acids alleviate cholestatic liver injury by improving gut microbiota and bile acid metabolism

Cholestasis, characterized by the obstruction of bile flow and the accumulation of bile acids, can lead to severe liver damage. Current treatments, such as ursodeoxycholic acid (UDCA) and obeticholic acid (OCA), are limited in effectiveness and have significant side effects, underscoring the need for new therapies. In our study, we investigated the effects of short-chain fatty acids (SCFAs) as a treatment in a mouse model of cholestasis induced by α-naphthylisothiocyanate (ANIT). Our findings demonstrated that SCFAs improved liver function, as indicated by reductions in liver function markers, decreased necrosis, and reduced bile duct proliferation and inflammation. Furthermore, SCFAs enhanced intestinal barrier function and increased the abundance of beneficial gut bacteria, such as Akkermansia muciniphila (A. muciniphila). SCFAs also triggered the FXR-Fgf15-Cyp7a1 pathway, reducing bile acid synthesis and improving bile acid metabolism. These findings indicate that SCFAs could offer a viable new treatment strategy for cholestatic liver conditions by improving gut-liver interactions, stabilizing bile acid metabolism, and alleviating inflammation.

EHBP1 suppresses liver fibrosis in metabolic dysfunction-associated steatohepatitis

Excess cholesterol accumulation contributes to fibrogenesis in metabolic dysfunction-associated steatohepatitis (MASH), but how hepatic cholesterol metabolism becomes dysregulated in MASH is not completely understood. We show that human fibrotic MASH livers have decreased EH-domain-binding protein 1 (EHBP1), a genome-wide association study (GWAS) locus associated with low-density lipoprotein (LDL) cholesterol, and that EHBP1 loss- and gain-of-function increase and decrease MASH fibrosis in mice, respectively. Mechanistic studies reveal that EHBP1 promotes sortilin-mediated PCSK9 secretion, leading to LDL receptor (LDLR) degradation, decreased LDL uptake, and reduced TAZ, a fibrogenic effector. At a cellular level, EHBP1 deficiency affects the intracellular localization of retromer, a protein complex required for sortilin stabilization. Our therapeutic approach to stabilizing retromer is effective in mitigating MASH fibrosis. Moreover, we show that the tumor necrosis factor alpha (TNF-α)/peroxisome proliferator-activated receptor alpha (PPARα) pathway suppresses EHBP1 in MASH. These data not only provide mechanistic insights into the role of EHBP1 in cholesterol metabolism and MASH fibrosis but also elucidate an interplay between inflammation and EHBP1-mediated cholesterol metabolism.

Longitudinal characterization of plasma and fecal bile acids in dairy heifers from birth to first calving in response to transition milk feeding

This study aimed to characterize plasma bile acid changes from birth to first calving and evaluate the effects of early transition milk (TM) feeding versus milk replacer (MR) during key stages. Fecal bile acids in TM-fed calves were also analyzed, offering insights into bile acid metabolism. Thirty female Holstein calves were fed TM or MR for the first 5 d, followed by 12 L/d MR. From d 14, calves were fed MR and starter with gradual weaning between wk 8 and 14. Blood samples were collected at 7 time points: 30 min and 12 h after birth, preweaning (wk 2, 6), weaning (wk 14), 8 mo, 13 mo, 3 wk before calving, at calving, and 3 wk after calving. Fecal samples were collected from a subset of TM-fed calves (n = 10) at birth, wk 6, wk 14, 8 mo, and calving. Samples were analyzed for bile acids using the Biocrates MxP Quant 500 kit. Cholic acid (CA) in plasma showed significant time-treatment interactions, with higher levels in TM-fed calves at weaning. Taurine- and glycine-conjugated bile acids had no treatment or time-treatment interactions, but all plasma bile acids showed significant time effects. Principal component analysis revealed that bile acid profiles at birth and after colostrum intake were tightly clustered. Plasma bile acid profiles showed greater dispersion during milk feeding and weaning, with tighter clustering observed postweaning, particularly at 13 mo, and in the transition period. Significant effects were observed for CA, deoxycholic acid (DCA) and chenodeoxycholic acid (CDCA), with CA showing a notable interaction and being higher in TM-fed calves at weaning than in MR-fed calves. Bile acid levels increased toward weaning, peaked at wk 14, and decreased after weaning. Glycine-conjugated bile acids changed over time, with glycocholic acid (GCA) and glycodeoxycholic acid (GDCA) peaking at weaning, and glycochenodeoxycholic acid (GCDCA) being elevated before weaning, decreasing thereafter, and increasing again at calving. Taurine-conjugated bile acids also showed temporal changes, peaking at wk 6. The shifts in bile acid composition from birth to postcalving, with taurolithocholic acid (TLCA), GDCA, and taurocholic acid (TCA) initially dominating, CA increasing at weaning, and GDCA and DCA dominating at calving, with CA increasing again postcalving. During the transition to calving, CA decreased whereas glycine-conjugated bile acids increased relative to taurine-conjugated bile acids in plasma, irrespective of treatment. Fecal bile acid profiles in TM-fed calves clustered distinctly at birth, evolving through pre- to postweaning and calving, with increasing profile overlap over time. Most fecal bile acids, except DCA and CA, were abundant at birth but declined over time. Both DCA and CA increased postweaning, mirroring plasma trends. From wk 6 to calving, DCA was the dominant bile acid, accounting for the highest percentage of total bile acids excreted in feces. Spearman's correlation analysis was performed to assess the relationship between plasma and fecal bile acids in TN-fed calves. A significant positive correlation was observed only for GCDCA (Spearman's rank correlation coefficient [rho] = 0.35), whereas all other bile acids were not correlated. These results illustrate the complex dynamics of bile acid profiles during calf development.

Complex system modeling reveals oxalate homeostasis is driven by diverse oxalate-degrading bacteria

Decades of research have made clear that host-associated microbiomes touch all facets of health. However, effective therapies that target the microbiome have been elusive given its inherent complexity. Here, we experimentally examined diet-microbe-host interactions through a complex systems framework, centered on dietary oxalate. Using multiple, independent molecular, rodent, and in vitro experimental models, we found that microbiome composition influenced multiple oxalate-microbe-host interfaces. Importantly, the administration of the oxalate-degrading specialist, Oxalobacter formigenes, was only effective against a poor oxalate-degrading microbiota background and gives critical new insights into why clinical intervention trials with this species exhibit variable outcomes. Data suggest that, while heterogeneity in the microbiome impacts multiple diet-host-microbe interfaces, metabolic redundancy among diverse microorganisms in specific diet-microbe axes is a critical variable that may impact the efficacy of bacteriotherapies, which can help guide patient and probiotic selection criteria in probiotic clinical trials.

Research Progress on the Mechanism of Bile Acids and Their Receptors in Depression

Depression, a highly prevalent mental disorder worldwide, arises from multifaceted interactions involving neurotransmitter imbalances, inflammatory responses, and gut-brain axis dysregulation. Emerging evidence highlights the pivotal role of bile acids (BAs) and their receptors, including farnesoid X receptor (FXR), Takeda G protein-coupled receptor 5 (TGR5), and liver X receptors (LXRs) in depression pathogenesis through modulation of neuroinflammation, gut microbiota homeostasis, and neural plasticity. Clinical investigations demonstrated altered BA profiles in depressed patients, characterized by decreased primary BAs (e.g., chenodeoxycholic acid (CDCA)) and elevated secondary BAs (e.g., lithocholic acid (LCA)), correlating with symptom severity. Preclinical studies revealed that BAs ameliorate depressive-like behaviors via dual mechanisms: direct CNS receptor activation and indirect gut-brain signaling, regulating neuroinflammation, oxidative stress, and BDNF/CREB pathways. However, clinical translation faces challenges including species-specific BA metabolism, receptor signaling complexity, and pharmacological barriers (e.g., limited blood-brain barrier permeability). While FXR/TGR5 agonists exhibit neuroprotective and anti-inflammatory potential, their adverse effects (pruritus, dyslipidemia) require thorough safety evaluation. Future research should integrate multiomics approaches and interdisciplinary strategies to develop personalized BA-targeted therapies, advancing novel treatment paradigms for depression.

Lactococcus petauri LZys1 modulates gut microbiota, diminishes ileal FXR-FGF15 signaling, and regulates hepatic function

Recent studies have indicated that Lactococcus petauri LZys1 (L. petauri LZys1), isolated from healthy human feces, exhibits a promising probiotic profile in vitro. However, its impact on the physiological status of the host in vivo remains uncertain. The objective of our study was to investigate the effects and mechanisms of orally administering L. petauri LZys1 on gut microbiota and liver function in mice. We administered L. petauri LZys1 through daily oral gavage to C57BL/6 male mice. Subsequently, we analyzed changes in gut microbiota composition using 16S rRNA sequencing and quantified alterations in hepatic-intestinal bile acid (BA) profile. Serum biochemical parameters were assessed to evaluate liver function. Our findings revealed that L. petauri LZys1 led to an increase in body weight, liver mass, and serum aminotransferase levels. Oral administration altered the gut microbiota composition, resulting in reduced diversity and abundance of intestinal bacteria. Additionally, the profiles of BAs were suppressed across organs, associated with the downregulation of the ileum's farnesoid X receptor (FXR)/fibroblast growth factor 15 (FGF15) signaling pathway. The decrease in circulating FGF15 mediated the downregulation of hepatic fibroblast growth factor receptor 4 (FGFR4)/FXR, disrupting BA metabolism and fatty acid oxidation. Our findings suggest that L. petauri LZys1 may impact liver function by influencing the gut microbiota-mediated ileal FXR-FGF15 axis and inhibiting hepatic bile acid metabolism.

IMPORTANCE

This work elucidated the impact of L. petauri LZys1 on host gut microbiota metabolism and hepatic physiological metabolism. We observed that L. petauri LZys1 administration induced liver weight gain and biochemical parameters changes, in addition to a altered gut microbiota and suppressed bile acid (BA) profiles. Furthermore, we propose that changes in liver status are related to the enterohepatic farnesoid X receptor-fibroblast growth factor axis, which alters bile acid metabolism and disrupts liver function. The above findings suggest that attention should be paid to the effect of probiotics on liver function.

The potential of pomegranate peel supplementation in Yellow-feathered broilers: effects on growth performance, serum biochemistry, antioxidant capacity, intestinal health, intestinal microbiota, and duodenal mucosal metabolites

This study aimed to investigate the effects of dietary supplementation with pomegranate peel powder (PP) on the growth performance, serum biochemistry, antioxidant capacity, intestinal microbiota, and duodenal mucosal metabolites of yellow-feathered broilers. A total of 360 yellow-feathered broilers were randomly divided into three groups, with their diets supplemented with different levels of PP (0, 1, and 4 g/kg) for 42 days. Dietary supplementation with PP significantly increased the average body weight and average daily gain of yellow-feathered broilers during the periods of 1-21 and 22-42 days, while reducing the feed conversion ratio (p < 0.05). It also decreased the serum levels of aspartate aminotransferase, alanine aminotransferase, creatinine, and uric acid, increased the activities of glutathione peroxidase and superoxide dismutase, and reduced malondialdehyde content in the serum, liver, and intestinal mucosa (p < 0.05). Furthermore, PP supplementation promoted the mRNA expression of farnesoid X receptor, peroxisome proliferator-activated receptor alpha, fatty acid-binding protein 4, epidermal growth factor/epidermal growth factor receptor, and B-cell lymphoma 2, while decreasing the mRNA expression of caspase-1 and interleukin-1 beta (p < 0.05). Regarding mucosal metabolites, PP supplementation increased the contents of polyunsaturated fatty acids (cis-11-eicosenoic acid, cis-13,16-docosadienoic acid, and cis-11,14-eicosadienoic acid), prostaglandin E2/G2, and secondary bile acids (apocholic, hyodeoxycholic, 7-ketodeoxycholic, and omega-muricholic acids) in the mucosa (p < 0.05). In terms of cecal microbiota, PP supplementation increased the β-diversity index (p < 0.05), elevated the relative abundances of Bacteroidota, Alistipes, Bacilli, and Actinobacteriota, and reduced the relative abundances of Clostridia and Gammaproteobacteria (p < 0.05). In conclusion, dietary supplementation of PP can improve intestinal health and growth performance of yellow-feathered broilers by regulating the composition of the gut microbiota.

Dietary bile acid supplementation influences protein digestibility and alters plasma amino acid profiles in broiler chickens fed conventional and reduced-protein diets

Reduced crude protein (CP) diets based on wheat have been shown to lower body weight (BW), increase feed conversion ratio (FCR), and elevate fat-pad deposition in broiler chickens. Bile acids facilitate lipid digestion and nutrient absorption by emulsifying fats and promoting micelle formation in the intestine. Therefore, it was hypnotized that supplementing reduced CP diets with bile acids may enhance fat utilization, improve energy efficiency, and mitigate the negative effects of low-CP diets on broiler performance and nutrient digestibility. Four dietary treatments were arranged in a 2 × 2 factorial layout, with two CP levels (standard and a 30 g/kg CP reduction), with or without 0.2 g/kg bile acids. A total of 840 off-sex male Ross 308 chicks were randomly assigned into 24 floor pens, with six replicates of 35 birds per treatment. From 0 to 42 days post-hatch, there was no interaction between dietary CP and bile acids supplementation for BW, feed intake (FI), FCR, abdominal fat pad, and nutrient digestibility (P > 0.05). As a main effect, reducing dietary CP decreased BW, FI, fat digestibility, and increased FCR and abdominal fat pad (P < 0.01). The reduced CP diet resulted in lower plasma concentrations of valine, isoleucine, arginine, histidine, phenylalanine, leucine, and tryptophan, while increasing lysine, methionine, and threonine concentrations (P < 0.01). Bile acids supplementation enhanced dry matter and protein digestibility (P < 0.05). Bile acids also showed a tendency to increase plasma methionine concentrations (P = 0.055). A significant interaction effect was observed for overall mortality, with bile acids supplementation reducing mortality in birds fed reduced CP diets (P < 0.01). These findings suggest that in reduced CP diets, the current ideal AA profile may be deficient in arginine and histidine, potentially contributing to increased fat pad weight. Elevated wheat-derived non-starch polysaccharide concentrations might lower fat digestibility in reduced CP diets. Supplementation of bile acids in these diets could mitigate endogenous taurine losses and improve overall health in broiler chickens.

The Effect of glycocholic acid on the growth, membrane permeability, conjugation and antibiotic susceptibility of Enterobacteriaceae

Introduction

Glycocholic acid (GCA) is a steroid acid and one of the main glycine-conjugated bile components in mammalian bile, which is involved in the emulsification and absorption of fats and sterols. It is long-known that the amphipathic nature of bile acids enables them to interact with the lipid membrane of Gram-positive bacteria and act as potent antimicrobial compounds. Nevertheless, Gram-negative Enterobacteriaceae species inhabiting the intestinal tract of mammals are considered to be more bile-resistant compared to Gram-positive bacteria and are thought to tolerate high bile concentrations.

Results

Here, we show that 1-2% of GCA inhibit the growth of Enterobacteriaceae species, including E. coli, Salmonella enterica. Klebsiella spp., Citrobacter spp., and Raoultella spp. during their late logarithmic phase in liquid culture, but not in solid media. Despite their lipopolysaccharide membrane layer, we demonstrate that, in liquid, GCA increases permeability, changes the surface of the Enterobacteriaceae membrane, and compromises its integrity. These changes result in leakage of cytoplasmic proteins and enhancement of their susceptibility to antibiotics. Moreover, GCA significantly reduces bacterial motility, the frequency of bacterial conjugation and horizontal acquisition of antibiotic resistance genes. These phenotypes are associated with repression of flagellin (fliC) transcription and a sharp decrease in the occurrence of conjugative pili in the presence of glycocholic acid, respectively.

Discussion

Overall, these findings broaden the current understanding about bile resistance of Gram-negative bacteria and suggest that GCA can be used to inhibit bacterial growth, augment the activity of antimicrobial compounds and diminish acquisition and dissemination of antibiotic resistance genes by conjugation.

Cholesterol 7 alpha-hydroxylase (CYP7A1) gene polymorphisms are associated with increased LDL-cholesterol levels and the incidence of subclinical atherosclerosis

The cholesterol 7 alpha-hydroxylase (CYP7A1) enzyme plays an important role in the conversion of cholesterol to bile acid, contributing to the reduction of cholesterol plasma levels in normal conditions. Nonetheless, recent studies have shown that some genetic variants in the enhancer and promoter regions of the CYP7A1 gene reduce the expression of the CYP7A1 enzyme, increasing plasma lipid levels, as well as the risk of developing coronary heart disease. The aim of this work was to explore whether the genetic variants (rs2081687, rs9297994, rs10107182, rs10504255, rs1457043, rs8192870, and rs3808607) of the CYP7A1 gene are involved in subclinical atherosclerosis and plasma lipid levels. We included 416 patients with subclinical atherosclerosis (SA) with coronary artery calcium (CAC) greater than zero, and 1046 controls with CAC = 0. According to the inheritance models (co-dominant, dominant, recessive, over-dominant and additive), the homozygosity of the minor allele frequencies of 7 analyzed polymorphisms showed a high incidence of SA (P < 0.05). In a sub-analysis performed including only the patients with SA, the same SNPs were associated with increased low-density lipoprotein cholesterol (LDL-C) levels. On the other hand, our findings showed that the haplotype (TGCGCTG) increases the risk of developing SA (P < 0.05). In conclusion, the rs2081687, rs9297994, rs10107182, rs10504255, rs1457043, rs8192870, and rs3808607 polymorphisms of CYP7A1 confer a risk of developing SA and elevated LDL-C levels. Our results suggest that the CYP7A1 is involved in the incidence of SA through the increase in the plasma lipid profile.

Effect of different Lys/Met ratios in a low-protein diet on the meat quality of Tibetan sheep: A transcriptomics- and metabolomics-based analysis

This study integrated the the effects of dietary Lys/Met ratio in a low protein diet on the meat quality in Tibetan sheep. A total of 90 weaned Tibetan sheep, 2 months old with initial weight of 15.37 ± 0.92 kg were randomly divided into 3 treatments, which were supplemented with Lys/Met ratio at 3 (LP-H), 2 (LP-M), and 1 (LP-L) in the basal diet (10 % crude protein), respectively. After slaughter (150 days of age), the growth performances and meat quality of longissimus dorsi muscle were evaluated. The LP-L group showed significantly higher final body weight compared to the LP-M group (P < 0.05). Serum albumin and total protein levels were significantly higher in the LP-L group than in the LP-H group (P < 0.05). Furthermore, meat from the LP-L group had significantly higher protein, calcium, and vitamin E content compared to the LP-M group (P < 0.05). Transcriptomic analysis revealed 3,479 differentially expressed genes enriched in pathways related to muscle growth, energy metabolism, and signaling transduction. Metabolomic analysis identified 771 differential metabolites, significantly enriched in ABC transporters, beta-alanine metabolism, and taste transduction pathways. Integrated analysis highlighted the upregulation of the ABCD4 gene and L-valine metabolite in the LP-L group, contributing to improved phenotypic traits. These findings provide molecular insights into the regulatory mechanisms underlying the effects of dietary Lys/Met ratios on Tibetan sheep meat quality and offer a basis for developing nutritional strategies to enhance premium meat production.

Application of physiologically based (PBK) modeling to quantify the effect of the antibiotic tobramycin on bile acid levels in human plasma

Systemic bile acid homeostasis plays an important role in human health. In this study, a physiologically based kinetic (PBK) model that includes microbial bile acid deconjugation and intestinal bile acid reuptake via the apical sodium-dependent bile acid transporter (ASBT) was applied to predict the systemic plasma bile acid concentrations in human upon oral treatment with the antibiotic tobramycin. Tobramycin was previously shown to inhibit intestinal deconjugation and reuptake of bile acids and to affect bile acid homeostasis upon oral exposure of rats. Kinetic parameters to define the effects of tobramycin on intestinal bile acid transport were determined in vitro using a Caco-2 cell layer Transwell model for studying the intestinal translocation of 4 model bile acids including glycochenodeoxycholic acid (GCDCA), glycocholic acid (GCA), glycodeoxycholic acid (GDCA), and deoxycholic acid (DCA), the latter as a model for unconjugated bile acids (uBA). Kinetic constants for the effect of tobramycin on intestinal microbial deconjugation were taken from previous in vitro studies using anaerobic fecal incubations. The PBK model simulations predicted that exposure to tobramycin at the dose level also used in the previous 28 day rat study would reduce human plasma Cmax levels of GCA, GCDCA, GDCA, and DCA by 42.4%, 27.7%, 16.9%, and 75.8%. The reduction of conjugated bile acids is governed especially via an effect on ASBT-mediated intestinal uptake, and not via the effect of tobramycin on intestinal conjugation, likely because deconjugation happens to a large extent in the colon which has limited subsequent bile acid reuptake. The results reflect that oral exposure to xenobiotics that are not or poorly bioavailable can affect systemic bile acid homeostasis. Altogether, the PBK model appears to provide a 3R compliant tool to evaluate the effect of oral exposure to xenobiotics on host bile acid homeostasis via effects on intestinal bile acid deconjugation and reuptake.

Trajectories of microbiome-derived bile acids in early life - insights into the progression to islet autoimmunity

Recent studies reveal that gut microbes produce diverse bile acid conjugates, termed microbially conjugated bile acids (MCBAs). However, their regulation and health effects remain unclear. Here, we analyzed early-life MCBA patterns and their link to islet autoimmunity. We quantified 110 MCBAs in 303 stool samples collected longitudinally (3-36 months) from children who developed one or more islet autoantibodies and controls who remained autoantibody-negative. Stool MCBAs showed distinct age-dependent trajectories and correlated with gut microbiome composition. Altered levels of ursodeoxycholic and deoxycholic acid conjugates were linked to islet autoimmunity as well as modulated monocyte activation in response to immunostimulatory lipopolysaccharide and Th17/Treg cell balance. These findings suggest MCBAs influence immune development and type 1 diabetes risk.

The effects of ursodeoxycholic acid on cardiometabolic risk factors: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Chronic diseases such as obesity, hypertension, and metabolic syndrome are major health concerns worldwide. Ursodeoxycholic acid (UDCA) is a bile acid that is naturally produced in the liver and has been used for the treatment of various liver disorders. In this systematic review and meta-analysis, we investigated how UDCA might affect inflammation, blood pressure, and obesity.

METHODS

Five major databases were searched from inception to August 2024. The investigated outcomes included body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). A random effect was carried out to estimate pooled weighted mean difference (WMD) with 95% confidence intervals (CI). The registration code is CRD42023428064.

RESULTS

Of the 7912 articles in the initial search, 12 were included in the systematic review and meta-analysis. UDCA consumption significantly decreased BMI (WMD: -0.29 kg/m2, 95% CI: -0.58, -0.01, P = 0.044), and DBP (WMD: -2.16 mmHg, 95% CI: -3.66, -0.66, P = 0.005). It also increased SBP (WMD: 5.50 mmHg, 95% CI: 3.65, 7.35, P < 0.001); however, it was not associated with weight loss (WMD: -0.3 kg, 95% CI: -1.3, 0.71, P = 0.561). Our systematic review showed that UDCA consumption has no effect on IL-6 and TNF-α.

CONCLUSION

This systematic review and meta-analysis suggest that UDCA supplementation may improve BMI and DBP, whereas it may increase SBP and have no effect on weight or inflammation. Further long-term and well-designed RCTs are needed to further assess and confirm these results.

Alterations in bile acid metabolites associated with pathogenicity and IVIG resistance in Kawasaki disease

Background

Kawasaki disease (KD) primarily affects children as an acute systemic vasculitis. Numerous studies indicated an elevated risk of cardiovascular disease due to metabolic disturbances. Despite this knowledge, the specific metabolic modes involved in KD remain unclear.

Methods

We examined the metabolome of individuals with 108 KD and 52 non-KD controls (KD vs. nKD) by ultraperformance liquid chromatography (UPLC) and tandem mass spectrometry (MS).

Results

Differential analysis uncovered the disturbed production of bile acids and lipids in KD. Furthermore, we investigated the impact of treatment, intravenous immunoglobulin (IVIG) resistance, and coronary artery (CA) occurrence on the metabolome. Our findings suggested that IVIG treatment alters the lipid and amino acid metabolism of KD patients. By orthogonal projections to latent structures discriminant analysis (OPLS-DA), there was no significant difference between the coronary injury groups and non-coronary injury groups, and IVIG resistance didn't appear to cause the metabolic change in KD patients.

Conclusions

Patients with KD exhibit metabolic abnormalities, particularly in bile acids and lipids. IVIG interventions may partially ameliorate these lipid abnormalities.

Bi-Directional Relationship Between Bile Acids (BAs) and Gut Microbiota (GM): UDCA/TUDCA, Probiotics, and Dietary Interventions in Elderly People

The gut microbiota (GM), the set of microorganisms that colonizes our intestinal tract, can undergo many changes, some of which are age related. Several studies have shown the importance of maintaining a healthy GM for a good quality of life. In the elderly, maintaining a good GM may become a real defense against infection by pathogens, such as C. difficile. In addition to the GM, bile acids (BAs) have been shown to provide an additional defense mechanism against the proliferation of pathogenic bacteria and to regulate bacterial colonization of the gut. BAs are molecules produced in the host liver and secreted with the bile into the digestive tract, and they are necessary for the digestion of dietary lipids. In the gut, host-produced BAs are metabolized by commensal bacteria to secondary BAs. In general GM and host organisms interact in many ways. This review examines the relationship between GM, BAs, aging, and possible new approaches such as dietary interventions, administration of ursodesoxycholic acid/tauroursodesoxycholic acid (UDCA/TUDCA), and probiotics to enrich the microbial consortia of the GM in the elderly and achieve a eubiotic state necessary for maintaining good health. The presence of Firmicutes and Actinobacteria together with adequate levels of secondary BAs would provide protection and improve the frailty state in the elderly. In fact, an increase in secondary BAs has been observed in centenarians who have reached old age without serious health issues, which may justify their active role in achieving longevity.

Complex system modelling reveals oxalate homeostasis is driven by diverse oxalate-degrading bacteria

Decades of research have made clear that host-associated microbiomes touch all facets of health. However, effective therapies that target the microbiome have been elusive given its inherent complexity. Here, we experimentally examined diet-microbe-host interactions through a complex systems framework, centered on dietary oxalate. Using multiple, independent molecular, animal, and in vitro experimental models, we found that microbiome composition influenced multiple oxalate-microbe-host interfaces. Importantly, administration of the oxalate-degrading specialist, Oxalobacter formigenes, was only effective against a poor oxalate-degrading microbiota background and gives critical new insights into why clinical intervention trials with this species exhibit variable outcomes. Data suggest that, while heterogeneity in the microbiome impacts multiple diet-host-microbe interfaces, metabolic redundancy among diverse microorganisms in specific diet-microbe axes is a critical variable that may impact the efficacy of bacteriotherapies, which can help guide patient and probiotic selection criteria in probiotic clinical trials.

Alterations in the Tongue Coating Microbiome in Patients With Diarrhea-Predominant Irritable Bowel Syndrome: A Cross-Sectional Study

The gut microbiota plays a critical role in the occurrence and development of IBS-D, however, IBS-D-associated tongue coating microbiome dysbiosis has not yet been clearly defined. To address this, we analyzed the structure and composition of the tongue coating microbiome in 23 IBS-D patients and 12 healthy controls using 16S rRNA high-throughput sequencing analysis. The 16S rRNA sequencing results revealed that the overall observed OTUs of tongue coating microbiome in IBS-D patients exhibited a significant decrease compared with the healthy controls. Alpha diversity analysis showed that the diversity and community richness were significantly reduced in IBS-D patients, and PCoA revealed a distinct clustering of tongue coating microbiome between the IBS-D patients and healthy controls. Microbial comparisons at the genus level showed that the abundance of Veillonella, Prevotella in IBS-D patients was higher than those in healthy controls, while Streptococcus, Haemophilus, Granulicatella, and Rothia were significantly reduced compared with the healthy volunteers. Functional analysis results showed significant differences in 88 functional metabolic pathways between the IBS-D patients and the healthy controls, including fatty acid biosynthesis. These findings identified the structure, composition, functionality of tongue coating microbiome in IBS-D patients, and hold promise the potential for therapeutic targets during IBS-D management.

Concentration-dependent effects of the nerve agents cyclosarin and VX on cytochrome P450 in a HepaRG cell-based liver model

The exposure to highly toxic organophosphorus (OP) compounds, including pesticides and nerve agents, is an ongoing medical challenge. OP can induce the uncontrolled overstimulation of the cholinergic system through inhibition of the enzyme acetylcholinesterase (AChE). The cytochrome P450 (CYP) enzymes in the liver play a predominant role in the metabolism of xenobiotics and are involved in the oxidative biotransformation of most clinical drugs. Previous research concerning the interactions between OP and CYP has usually focused on organothiophosphate pesticides that require CYP-mediated bioactivation to their active oxon metabolites to act as inhibitors of AChE. Since there has been little data available concerning the effect of nerve agents on CYP, we performed a study with cyclosarin (GF) and O-ethyl-S-[2-(diisopropylamino)-ethyl]-methylphosphonothioate (VX) by using a well-established, metabolically competent in vitro liver model (HepaRG cells). The inhibitory effect of the nerve agents GF and VX on the CYP3A4 enzyme was investigated showing a low CYP3A4 inhibitory potency. Changes on the transcription level of CYP and associated oxygenases were evaluated by quantitative reverse transcription polymerase chain reaction (qRT-PCR) using the two nerve agent concentrations 250 nM and 250 μM. In conclusion, the results demonstrated various effects on oxygenase-associated genes in dependence of the concentration and the structure of the nerve agent. Such information might be of relevance for potential interactions between nerve agents, antidotes or other clinically administered drugs, which are metabolized by the affected CYP, for example, for the therapy with benzodiazepines, that are used for the symptomatic treatment of OP poisoning and that require CYP-mediated biotransformation.

Host metabolism balances microbial regulation of bile acid signalling

Metabolites derived from the intestinal microbiota, including bile acids (BA), extensively modulate vertebrate physiology, including development1, metabolism2-4, immune responses5-7 and cognitive function8. However, to what extent host responses balance the physiological effects of microbiota-derived metabolites remains unclear9,10. Here, using untargeted metabolomics of mouse tissues, we identified a family of BA-methylcysteamine (BA-MCY) conjugates that are abundant in the intestine and dependent on vanin 1 (VNN1), a pantetheinase highly expressed in intestinal tissues. This host-dependent MCY conjugation inverts BA function in the hepatobiliary system. Whereas microbiota-derived free BAs function as agonists of the farnesoid X receptor (FXR) and negatively regulate BA production, BA-MCYs act as potent antagonists of FXR and promote expression of BA biosynthesis genes in vivo. Supplementation with stable-isotope-labelled BA-MCY increased BA production in an FXR-dependent manner, and BA-MCY supplementation in a mouse model of hypercholesteraemia decreased lipid accumulation in the liver, consistent with BA-MCYs acting as intestinal FXR antagonists. The levels of BA-MCY were reduced in microbiota-deficient mice and restored by transplantation of human faecal microbiota. Dietary intervention with inulin fibre further increased levels of both free BAs and BA-MCY levels, indicating that BA-MCY production by the host is regulated by levels of microbiota-derived free BAs. We further show that diverse BA-MCYs are also present in human serum. Together, our results indicate that BA-MCY conjugation by the host balances host-dependent and microbiota-dependent metabolic pathways that regulate FXR-dependent physiology.

Schisandrol B alleviates depression-like behavior in mice by regulating bile acid homeostasis in the brain-liver-gut axis via the pregnane X receptor

BACKGROUND

Depression is a widely recognized neuropsychiatric disorder. Recent studies have shown a potential correlation between bile acid disorders and depression, highlighting the importance of maintaining bile acid balance for effective antidepressant treatment. Schisandrol B (SolB), a primary bioactive compound from Schisandra chinensis (Turcz.) Baill. or Schisandra sphenanthera Rehd.etWils, is pivotal in regulating bile acid homeostasis via pregnane X receptor (PXR) in cholestasis. However, the potential of SolB in alleviating depression-like symptoms, its pharmacological effects, and the underlying mechanisms remain to be fully elucidated.

METHODS

We confirmed the effect of SolB against depression induced by chronic restraint stress (CRS) and chronic unpredictable mild stress (CUMS) in mice. The role of SolB in bile acid homeostasis in depression was analyzed using the metabolomic. Gene analyses and 16S rRNA sequencing were employed to investigate the involvement of PXR. Experiments with Pxr-/- mice were conducted to confirm the essential role of the PXR pathway in SolB's antidepressant effects.

RESULTS

SolB treatment significantly increased sucrose consumption in the SPT and the locomotor activity in the OFT, while decreasing immobility time in the FST and TST in mice exposed to CRS and CUMS. Additionally, SolB treatment significantly preserved the integrity of the dendritic spine, elevated synaptic protein PSD95 levels, and augmented CREB/BDNF expression. Metabolomic and gene analyses indicated that SolB treatment significantly facilitated bile acid metabolism, promoted intestinal bile acid efflux, decreased hippocampal levels of the secondary bile acids DCA and TLCA, and upregulated expression of the PXR target proteins CYP3A11, SULT2A1, MRP2, and OATP1B1 in the liver, and MRP2 and MDR1 in hippocampus, which are integral to bile acid homeostasis. 16S rRNA sequencing revealed that SolB reduced the abundance of the bile salt hydrolase (BSH)-producing bacteria Lactobacillus johnsonii and Bacteroides fragilis and subsequently decreased the production of TLCA and DCA. Moreover, SolB failed to protect against depression induced by CRS in Pxr-null mice, suggesting that the antidepressant effect of SolB was PXR-dependent.

CONCLUSIONS

These results provide direct evidence of the antidepressant effect of SolB via activation of PXR to regulate bile acid homeostasis in the brain-liver-gut axis, suggesting that SolB may serve as a novel potential target for preventing and treating depression.

The gut microbiome modulate response to immunotherapy in cancer

Gut microbiota have been reported to play an important role in the occurrence and development of malignant tumors. Currently, clinical studies have identified specific gut microbiota and its metabolites associated with efficacy of immunotherapy in multiple types of cancers. Preclinical investigations have elucidated that gut microbiota modulate the antitumor immunity and affect the efficacy of cancer immunotherapy. Certain microbiota and its metabolites may favorably remodel the tumor microenvironment by engaging innate and/or adaptive immune cells. Understanding how the gut microbiome interacts with cancer immunotherapy opens new avenues for improving treatment strategies. Fecal microbial transplants, probiotics, dietary interventions, and other strategies targeting the microbiota have shown promise in preclinical studies to enhance the immunotherapy. Ongoing clinical trials are evaluating these approaches. This review presents the recent advancements in understanding the dynamic interplay among the host immunity, the microbiome, and cancer immunotherapy, as well as strategies for modulating the microbiome, with a view to translating into clinical applications.

Bile acids acting as a feeding signal and functional foods mimicking bile acid function

To elucidate the function of the bile acid-binding receptor TGR5 in skeletal muscle, we developed transgenic mice expressing human TGR5 in the skeletal muscle tissue. A significant increase in muscle mass was observed in these transgenic mice, whereas a decrease in muscle mass was observed in the TGR5-deficient mice. Following treadmill exercise, TGR5 gene expression increased in response to ER stress induced in skeletal muscle via an ER stress response motif present in its promoter region. Exercise and rapid postprandial elevation in blood bile acid concentrations can be considered the primary stimuli for the TGR5-mediated increase in skeletal muscle mass. We developed a scoring system to identify food ingredients with TGR5 agonist activity, and identified the citrus limonoid nomilin. Similar effects were observed for other triterpenoids in addition to nomilin. Cell culture and in vivo experiments demonstrated that these food factors increase protein synthesis and muscle mass.

Trichosanthes kirilowii Maxim. Polysaccharide attenuates diabetes through the synergistic impact of lipid metabolism and modulating gut microbiota

Polysaccharide, a chain of sugars bound by glycosidic bonds, have a wide range of physiological activities, including hypoglycemic activity. In present study, we established T2DM mice models to explore the effects and mechanism of Trichosanthes kirilowii Maxim polysaccharide (TMSP1) on high-fat diet/streptozotocin (HF-STZ) induced diabetes mice. The results showed that high-fat diet significantly increased the oral glucose tolerance test (OGTT), viscera index, oxidative stress, impaired glucose tolerance, decreased body weight, immune response and short-chain fatty acid (SCFAs) content, and disrupted the balance of intestinal flora structure. However, after 6 weeks of TMSP1 intervention decreased lipid accumulation, ameliorated gut microbiota dysbiosis by increasing SCFAs-producing bacteria and mitigated intestinal inflammation and oxidative stress. Moreover, TMSP1 significantly restored the integrity of the intestinal epithelial barrier and mucus barrier. The results of fecal microbiota transplantation confirmed that TMSP1 exerted hypoglycemic effect through regulating intestinal flora to a certain extent. Collectively, the findings revealed TMSP1 intervention inhibits hyperglycemia by improving gut microbiota disorder, lipid metabolism, and inflammation. Hence, TMSP1 may be an effective measure to ameliorate HF-STZ induced diabetes.

Positive autoregulation of Sox17 is necessary for gallbladder and extrahepatic bile duct formation

Expression of SRY-box transcription factor 17 (Sox17) in the endodermal region caudal to the hepatic diverticulum during late gastrulation is necessary for hepato-pancreato-biliary system formation. Analysis of an allelic series of promoter-proximal mutations near the transcription start site (TSS) 2 of Sox17 in mouse has revealed that gallbladder (GB) and extrahepatic bile duct (EHBD) development is exquisitely sensitive to Sox17 expression levels. Deletion of a SOX17-binding cis-regulatory element in the TSS2 promoter impairs GB and EHBD development by reducing outgrowth of the nascent biliary bud. These findings reveal the existence of a SOX17-dependent autoregulatory loop that drives Sox17 expression above a critical threshold concentration necessary for GB and EHBD development to occur, and that minor impairments in Sox17 gene expression are sufficient to impair the expression of SOX17-regulated genes in the nascent GB and EHBD system, impairing or preventing development.

The bile acid profile

As a large and structurally diverse family of small molecules, bile acids play a crucial role in regulating lipid, glucose, and energy metabolism. In the human body, bile acids share a similar chemical structure with many isomers, exhibit little difference in polarity, and possess various physiological activities. The types and contents of bile acids present in different diseases vary significantly. Therefore, comprehensive and accurate detection of the content of various types of bile acids in different biological samples can not only provide new insights into the pathogenesis of diseases but also facilitate the exploration of novel strategies for disease diagnosis, treatment, and prognosis. The detection of disease-induced changes in bile acid profiles has emerged as a prominent research focus in recent years. Concurrently, targeted metabolomics methods utilizing high-performance liquid chromatography-mass spectrometry (HPLC-MS) have progressively established themselves as the predominant technology for the separation and detection of bile acids. Bile acid profiles will increasingly play an important role in diagnosis and guidance in the future as the relationship between disease and changes in bile acid profiles becomes clearer. This highlights the growing diagnostic value of bile acid profiles and their potential to guide clinical decision-making. This review aims to explore the significance of bile acid profiles in clinical diagnosis from four perspectives: the synthesis and metabolism of bile acids, techniques for detecting bile acid profiles, changes in bile acid profiles associated with diseases, and the challenges and future prospects of applying bile acid profiles in clinical settings.

Hepatic FXR-FGF4 is required for bile acid homeostasis via an FGFR4-LRH-1 signal node under cholestatic stress

Bile acid (BA) homeostasis is vital for various physiological processes, whereas its disruption underlies cholestasis. The farnesoid X receptor (FXR) is a master regulator of BA homeostasis via the ileal fibroblast growth factor (FGF)15/19 endocrine pathway, responding to postprandial or abnormal transintestinal BA flux. However, the de novo paracrine signal mediator of hepatic FXR, which governs the extent of BA synthesis within the liver in non-postprandial or intrahepatic cholestatic conditions, remains unknown. We identified hepatic Fgf4 as a direct FXR target that paracrinally signals to downregulate Cyp7a1 and Cyp8b1. The effect of FXR-FGF4 is mediated by an uncharted intracellular FGF receptor 4 (FGFR4)-LRH-1 signaling node. This liver-centric pathway acts as a first-line checkpoint for intrahepatic and transhepatic BA flux upstream of the peripheral FXR-FGF15/19 pathway, which together constitutes an integral hepatoenteric control mechanism that fine-tunes BA homeostasis, counteracting cholestasis and hepatobiliary damage. Our findings shed light on potential therapeutic strategies for cholestatic diseases.

Drug-induced cholestasis (DIC) predictions based on in vitro inhibition of major bile acid clearance mechanisms

Drug-induced cholestasis (DIC) is recognized as a major safety concern in drug development, as it represents one of the three types of drug-induced liver injury (DILI). Cholestasis is characterized by the disruption of bile flow, leading to intrahepatic accumulation of toxic bile acids. Bile acid regulation is a multifarious process, orchestrated by several hepatic mechanisms, namely sinusoidal uptake and efflux, canalicular secretion and intracellular metabolism. In the present study, we developed a prediction model of DIC using in vitro inhibition data for 47 marketed drugs on nine transporters and five enzymes known to regulate bile acid homeostasis. The resulting model was able to distinguish between drugs with or without DILI concern (p-value = 0.039) and demonstrated a satisfactory predictive performance, with the area under the precision-recall curve (PR AUC) measured at 0.91. Furthermore, we simplified the model considering only two processes, namely reversible inhibition of OATP1B1 and time-dependent inhibition of CYP3A4, which provided an enhanced performance (PR AUC = 0.95). Our study supports literature findings suggesting a contribution not only from a single process inhibition, but a rather synergistic effect of the key bile acid clearance processes in the development of cholestasis. The use of a quantitative model in the preclinical investigations of DIC is expected to reduce attrition rate in advanced development programs and guide the discovery and development of safe medicines.

An integrated analysis of bile acid metabolism in humans with severe obesity

BACKGROUND AND AIMS

Bile acids (BA) are vital regulators of metabolism. BAs are AQ6 secreted in the small intestine, reabsorbed, and transported back to the liver, where they can modulate metabolic functions. There is a paucity of data regarding the portal BA composition in humans. This study aimed to address this knowledge gap by investigating portal BA composition and the relation with peripheral and fecal BA dynamics in conjunction with the gut microbiome.

APPROACH AND RESULTS

Thirty-three individuals from the BARIA cohort were included. Portal plasma, peripheral plasma, and feces were collected. BA and C4 levels were measured employing mass spectrometry. FGF19 was measured using ELISA. Gut microbiota composition was determined through metagenomics analysis on stool samples. Considerable diversity in the portal BA composition was observed. The majority (n = 26) of individuals had a 9-fold higher portal than peripheral BA concentration. In contrast, 8 individuals showed lower portal BA concentration compared with peripheral and had higher levels of unconjugated and secondary BA in this compartment, suggesting more distal origin. The altered portal BA profile was associated with altered gut microbiota composition. In particular, taxa within Bacteroides were reduced in abundance in the feces of these individuals.

CONCLUSIONS

Characterization of the portal BA composition in relation to peripheral and fecal BA increased insight into the dynamics of BA metabolism in individuals with obesity. Peripheral BA composition was much more diverse due to microbial metabolism. About 24% of the portal samples was surprisingly low in total BA; the underlying mechanism requires further exploration.

Rebalancing immune homeostasis in combating disease: The impact of medicine food homology plants and gut microbiome

BACKGROUND

Gut microbiota plays an important role in multiple human physiological processes and an imbalance in it, including the species, abundance, and metabolites can lead to diseases. These enteric microorganisms modulate immune homeostasis by presenting a myriad of antigenic determinants and microbial metabolites. Medicinal and food homologous (MFH) plants, edible herbal materials for both medicine and food, are important parts of Traditional Chinese Medicine (TCM). MFH plants have drawn much attention due to their strong biological activity and low toxicity. However, the interplay of MFH and gut microbiota in rebalancing the immune homeostasis in combating diseases needs systematic illumination.

PURPOSE

The review discusses the interaction between MFH and gut microbiota, including the effect of MFH on the major group of gut microbiota and the metabolic effect of gut microbiota on MFH. Moreover, how gut microbiota influences the immune system in terms of innate and adaptive immunity is addressed. Finally, the immunoregulatory mechanisms of MFH in regulation of host pathophysiology via gut microbiota are summarized.

METHODS

Literature was searched, analyzed, and collected using databases, including PubMed, Web of Science, and Google Scholar using relevant keywords. The obtained articles were screened and summarized by the research content of MFH and gut microbiota in immune regulation.

RESULTS

The review demonstrates the interaction between MFH and gut microbiota in disease prevention and treatment. Not only do the intestinal microorganisms and intestinal mucosa constitute an important immune barrier of the human body, but also lymphoid tissue and diffused immune cells within the mucosa participate in the response of innate immunity and adaptive immunity. MFH modulates immune regulation by affecting intestinal flora, helps maintain the balance of the immune system and interfere with the occurrence and development of a broad category of diseases.

CONCLUSION

Being absorbed from the gastrointestinal tract, MFH can have profound effects on gut microbiota. In turn, the gut microbiota also actively participate in the bioconversion of complex constituents from MFH, which could further influence their physiological and pharmacological properties. The review deepens the understanding of the relationship among MFH, gut microbiota, immune system, and human diseases and further promotes the progression of additional relevant research.

Non-SCFA microbial metabolites associated with fiber fermentation and host health

Dietary fiber is degraded by commensal gut microbes to yield host-beneficial short-chain fatty acids (SCFAs), but personalized responses to fiber supplementation highlight a role for other microbial metabolites in shaping host health. In this review we summarize recent findings from dietary fiber intervention studies describing health impacts attributed to microbial metabolites other than SCFAs, particularly secondary bile acids (2°BAs), aromatic amino acid derivatives, neurotransmitters, and B vitamins. We also discuss shifts in microbial metabolism occurring through altered maternal dietary fiber intake and agricultural practices, which warrant further investigation. To optimize the health benefits of dietary fibers, it is essential to survey a range of metabolites and adapt recommendations on a personalized basis, according to the different functional aspects of the microbiome.

Gut microbiota-mediated bile acid metabolism aggravates biliary injury after liver transplantation through mitochondrial apoptosis

Ischemic-type biliary lesions (ITBL) are a major cause of graft loss and even mortality after liver transplantation (LT). The underlying cellular mechanisms for ITBL remain unclear. Gut microbiota has been found to be closely related to complications after LT. Here, using gut microbiome compositions, we found patients with ITBL had a higher abundance of bacteria associated with bile salt metabolism. These bacteria are reported to convert cholic acid (CA) into deoxycholic acid (DCA), consistent with our data that there were higher DCA concentrations and DCA/CA ratio in patients with ITBL than patients without ITBL. Using an in vitro model, human intrahepatic biliary epithelial cells (HIBEC) subjected to DCA showed a higher apoptosis rate, lower viability, and higher levels of cleaved-caspase3 than CA at the same concentration. DCA also changed the morphology of mitochondria and farnesoid X receptor (FXR) expression. Interestingly, DCA-induced apoptosis rate was significantly reduced in HIBEC when the FXR or BAX gene was knocked down, suggesting that DCA-induced apoptosis was dependent on FXR-mitochondrial pathway. Furthermore, increasing DCA/CA ratio in a bile acid-feeding mouse model resulted in cholangiocyte apoptosis and impaired liver function. The patients with ITBL also showed an increased proportion of TUNEL-positive biliary epithelial cells than those without ITBL. These suggest that changes in the gut microbiota following LT may enhance the conversion of CA to DCA, and may contribute to biliary damage via FXR-mitochondrial apoptosis pathway, providing new ideas for the early monitoring and treatment of ITBL.

Conjugated bile acids alleviate acute pancreatitis through inhibition of TGR5 and NLRP3 mediated inflammation

INTRODUCTION

Severe acute pancreatitis (SAP) is a crucial gastrointestinal disease characterized by systemic inflammatory responses and persistent multiple organ failure. The role of bile acids (BAs) in diverse inflammatory diseases is increasingly recognized as crucial, but the underlying role of BA conjugation remains elusive.

OBJECTIVES

Our study aim to investigate the potential role of conjugated bile acids in SAP and reveal the molecular mechanisms underlying its regulatory effects. We hypothesized that taurochenodeoxycholic acid (TCDCA) and glycochenodeoxycholic acid (GCDCA) could protect SAP through inhibiting the activation of NLRP3 inflammasomes via the TGR5 pathway in macrophages.

METHODS

To test our hypothesis, we used BA-CoA: amino acid N-acyltransferase knockout (Baat-/-) mice and established SAP mouse models using caerulein- and sodium taurocholate- induced. We utilized a range of methods, including pathology sections, qRT-PCR, immunofluorescence, Western blotting, and ELISA, to identify the mechanisms of regulation.

RESULTS

BA-CoA: Amino acid N-acyltransferase knockout (Baat-/-) mice significantly exacerbated pancreatitis by increasing pancreatic and systemic inflammatory responses and pancreatic damage in SAP mouse models. Moreover, the serum TCDCA levels in Baat-/- mice were lower than those in wild-type (WT) mice with or without SAP, and GCDCA and TCDCA showed stronger anti-inflammatory effects than chenodeoxycholic acid (CDCA) in vitro. TCDCA treatment alleviated SAP in a Takeda G protein-coupled receptor 5 and NOD-like receptor family, pyrin domain containing 3-dependent manner in vivo. Reinforcing our conclusions from the mouse study, clinical SAP patients exhibited decreased serum content of conjugated BAs, especially GCDCA, which was inversely correlated with the severity of systemic inflammatory responses.

CONCLUSION

Conjugated bile acids significantly inhibit NLRP3 inflammasome activation by activating TGR5 pathway, thereby alleviating pancreatic immunopathology. The results provide new insights into the variability of clinical outcomes and paves the way for developing more effective therapeutic interventions for AP.

Maternal high-fat diet orchestrates offspring hepatic cholesterol metabolism via MEF2A hypermethylation-mediated CYP7A1 suppression

BACKGROUND

Maternal overnutrition, prevalent among women of childbearing age, significantly impacts offspring health throughout their lifetime. While DNA methylation of metabolic-related genes mediates the transmission of detrimental effects from maternal high-fat diet (HFD), its role in programming hepatic cholesterol metabolism in offspring, particularly during weaning, remains elusive.

METHODS

Female C57BL/6 J mice were administered a HFD or control diet, before and during, gestation and lactation. Hepatic cholesterol metabolism genes in the liver of offspring were evaluated in terms of their expression. The potential regulator of cholesterol metabolism in the offspring's liver was identified, and the function of the targeted transcription factor was evaluated through in vitro experiments. The methylation level of the target transcription factor was assessed using the MassARRAY EpiTYPER platform. To determine whether transcription factor expression is influenced by DNA methylation, in vitro experiments were performed using 5-azacitidine and Lucia luciferase activity assays.

RESULTS

Here, we demonstrate that maternal HFD results in higher body weight and hypercholesterolemia in the offspring as early as weaning age. Maternal HFD feeding exacerbates hepatic cholesterol accumulation in offspring primarily by inhibiting cholesterol elimination to bile acids, with a significant decrease of hepatic cholesterol 7α-hydroxylase (CYP7A1). RNA-seq analysis identified myocyte enhancer factor 2A (MEF2A) as a key transcription factor in the offspring liver, which was significantly downregulated in offspring of HFD-fed dams. MEF2A knockdown led to CYP7A1 downregulation and lipid accumulation in HepG2 cells, while MEF2A overexpression reversed this effect. Dual luciferase reporter assays confirmed direct modulation of CYP7A1 transcription by MEF2A. Furthermore, the reduced MEF2A expression was attributed to DNA hypermethylation in the Mef2a promoter region. This epigenetic modification manifested as early as the fetal stage.

CONCLUSIONS

This study provides novel insights into how maternal HFD orchestrates hepatic cholesterol metabolism via MEF2A hypermethylation-mediated CYP7A1 suppression in offspring at weaning.

Effects of Several Bile Acids on the Production of Virulence Factors by Pseudomonas aeruginosa

The presence of bile acids in the cystic fibrosis patient's lungs contributes to an increase in the inflammatory response, in the dominance of pathogens, as well as in the decline in lung function, increasing morbidity. The aim of this study is to determine the effects of exposure of Pseudomonas aeruginosa to primary and secondary bile acids on the production of several virulence factors which are involved in its pathogenic power. The presence of bile acids in the bacterial culture medium had no effect on growth up to a concentration of 1 mM. However, a slight decrease in the adhesion index as well as a reduction in the virulence of the bacteria on the HT29 cell line could be observed. In this model, exposure of P. aeruginosa to bile acids showed a significant decrease in the production of LasB and AprA proteases due to the reduction in the expression of their genes. A decrease in pyocyanin production was also observed in relation to the effects of bile acids on the quorum sensing regulators. In order to have an effect on gene expression, it is necessary for bile acids to enter the bacteria. P. aeruginosa harbors two potential homologs of the eukaryotic genes encoding the bile acid transporters NTCP1 and NTCP2 that are expressed in hepatocytes and enterocytes, respectively. By carrying out a comparative BLAST-P between the amino acid sequences of the PAO1 proteins and those of NTCP1 and NTCP2, we identified the products of the PA1650 and PA3264 genes as the unique homologs of the two eukaryotic genes. Exposure of the mutant in the PA1650 gene to chenodeoxycholic acid (CDCA) and lithocholic acid (LCA) showed a less significant effect on pyocyanin production than with the isogenic PAO1 strain. Also, no effect of CDCA on the PA3264 gene mutant was observed. This result indicated that CDCA should enter the bacteria by the transporter produced by this gene. The entry of LCA into bacteria seemed more complex and rather responded to a multifactorial system involving the product of the PA1650 gene but also the products of other genes encoding potential transporters.

Identification of 7-HOCA as a Potential Biomarker in Glioblastoma: Evidence from Genome-Wide Association Study and Clinical Validation

Purpose

Glioblastoma (GBM) is associated with metabolic disturbances, yet the relationships between metabolites with GBM have not been comprehensively explored. This study aims to fill this gap by integrating Mendelian randomization (MR) analysis with clinical validation.

Patients and Methods

Summary data from genome-wide association study (GWAS) of cerebrospinal fluid (CSF) metabolites, plasma metabolites, and GBM were obtained separately. A total of 338 CSF metabolites and 1400 plasma metabolites were utilized as exposures. Concurrently, GBM was designated as the outcome. A two-sample bidirectional MR study was conducted to investigate the potential association. The inverse variance weighted (IVW) analyses were conducted as causal estimates, accompanied by a series of sensitivity analyses to evaluate the robustness of the results. Additionally, metabolite levels in clinical plasma and CSF samples were quantified using liquid chromatography-mass spectrometry to validate the findings.

Results

MR analysis identified eight CSF metabolites and six plasma metabolites that were closely associated with GBM. Among these, elevated levels of 7-alpha-hydroxy-3-oxo-4-cholestenoate (7-HOCA) in both CSF and plasma were found to promote GBM. In terms of clinical validation, compared to the control group, 7-HOCA levels were significantly higher in both the CSF and plasma of GBM group.

Conclusion

This study provides a comprehensive analysis of the metabolic factors contributing to GBM. The identification of specific metabolites, particularly 7-HOCA, that have vital roles in GBM pathogenesis suggests new biomarkers and therapeutic targets, offering potential pathways for improved diagnosis and treatment of GBM.

Structure-guided discovery of bile acid derivatives for treating liver diseases without causing itch

Chronic itch is a debilitating symptom profoundly impacting the quality of life in patients with liver diseases like cholestasis. Activation of the human G-protein coupled receptor, MRGPRX4 (hX4), by bile acids (BAs) is implicated in promoting cholestasis itch. However, the detailed underlying mechanisms remain elusive. Here, we identified 3-sulfated BAs that are elevated in cholestatic patients with itch symptoms. We solved the cryo-EM structure of hX4-Gq in a complex with 3-phosphated deoxycholic acid (DCA-3P), a mimic of the endogenous 3-sulfated deoxycholic acid (DCA-3S). This structure revealed an unprecedented ligand-binding pocket in MRGPR family proteins, highlighting the crucial role of the 3-hydroxyl (3-OH) group on BAs in activating hX4. Guided by this structural information, we designed and developed compound 7 (C7), a BA derivative lacking the 3-OH. Notably, C7 effectively alleviates hepatic injury and fibrosis in liver disease models while significantly mitigating the itch side effects.

Diammonium glycyrrhizinate alleviates iron overload-induced liver injury in mice via regulating the gut-liver axis

BACKGROUND

Evidence indicates a close association between iron overload (IO) and the pathogenesis of chronic liver diseases, highlighting the potential for interventions targeted at IO to impede or decelerate the progression of chronic liver diseases. Diammonium glycyrrhizinate (DG), the medicinal form of glycyrrhizic acid, a principal constituent of licorice, has been clinically employed as a hepatoprotective agent; however, its protective effect against IO-induced liver injury and underlying molecular mechanisms remain elusive.

PURPOSE

The aim of the present study is to investigate the hepatoprotective effect of DG against IO-induced liver injury with a focus on the gut-liver axis.

STUDY DESIGN AND METHODS

Animal models of IO-induced liver injury and DG treatment have been established in vivo. Iron deposition, liver injury, intestinal barrier damage, and liver inflammation were assessed in mice treated with iron dextran or DG. The microbiome composition in feces was analyzed using 16S rRNA full-length sequencing. Bile acids (BAs) profiles in feces were detected by UPLC-Q-TOF-MS technique, and the expression levels of receptors, enzymes or transporters involved in BAs metabolism were also determined.

RESULTS

DG partially reduced the iron deposition and the levels of ferrous ion in the livers of mice with IO, thereby mitigating oxidative damage. DG also improved gut microbiota dysbiosis, repaired intestinal barrier damage, inhibited endotoxin translocation to the liver, and subsequently suppressed TLR4/NF-κB/NLRP3 pathway-mediated liver inflammation caused by IO. Moreover, DG modulated BAs metabolism disorder in IO mice, reducing the accumulation of BAs in the liver.

CONCLUSION

DG alleviates IO-induced liver injury in mice by regulating the gut-liver axis. This study provides novel insights into the underlying mechanisms through which DG ameliorates liver injury caused by IO.

Dietary supplementation of poly-dihydromyricetin-fused zinc nanoparticles alleviates fatty liver hemorrhagic syndrome by improving antioxidant capacity, intestinal health and lipid metabolism of laying hens

Fatty liver hemorrhagic syndrome is the main cause of noninfectious death of laying hens and results in substantial economic losses to the poultry industry. This study focused on evaluating the effects of Poly-dihydromyricetin-fused zinc nanoparticles (PDMY-Zn NPs) on antioxidant capacity, liver lipid metabolism, and intestinal health in laying hens. A total of 288 Jingfen laying hens (52 wk old) with similar body weights were randomly divided into 4 dietary groups with 6 replicates in each group for 8 wk. The control group received a basal diet, while the treatment groups were supplemented with PDMY-Zn NPs at levels of 200, 400, and 600 mg/kg, respectively. The results indicate that PDMY-Zn NPs supplementation can enhance antioxidant parameters (P < 0.05) in the blood and liver of laying hens. Simultaneously, it can mitigate vacuolar degeneration and inflammatory necrosis in hepatocytes, improve the relative expression level of related parameters associated with liver lipid metabolism and key regulatory genes (P < 0.05). Furthermore, it has been observed to reshape the composition and diversity of cecum microbes by increasing beneficial probiotics such as Lactobacillus and Prevotella, while also enhancing villi height and villi/crypt ratio in the duodenum and ileum (P < 0.05). Additionally, it elevates liver bile acid content along with the relative expression of key genes involved in liver synthesis (P < 0.05). In summary, PDMY-Zn NPs showed potential to alleviate fatty liver hemorrhagic syndrome by enhancing antioxidant capacity, regulating liver lipid metabolism, and maintaining intestinal health.