Total Fecal Bile Acid Research Articles

P0596 Fecal bile acids predict the therapeutic effect of biological agents in patients with ulcerative colitis

Abstract Background Ulcerative colitis (UC) is a chronic non-specific inflammatory disease of the colon. Infliximab or vedolizumab is recommended for treatment of moderate to severe UC, but has a primary or secondary non-response rate. Receiving early predictions on treatment efficacy can offer substantial support for patients’ therapeutic interventions. We aim to use fecal bile acids to identify predictive biomarkers. Methods Fecal samples were collected from 55 UC patients hospitalized in the Second Hospital of Hebei Medical University and 10 healthy volunteers. UC patients were divided into clinical response group and clinical non-response group according to the therapeutic effect of biologics. Quantitative detection of target bile acids was performed on fecal samples. The bile acid levels of the two groups were compared, and the bile acids that predicted the therapeutic effect were screened by orthogonal partial least squares discriminant analysis (OPLS-DA) and the analysis of receiver working characteristic curve. Results Compared with healthy adults, patients with UC showed decreased total fecal bile acids, increased primary bile acids, and decreased secondary bile acids. After treatment with biologics, there was a decrease in primary bile acids and an increase in secondary bile acids. In comparison between clinical responders and non-responders, fecal lithocholic acid and deoxycholic acid were significantly increased, and the ratio of primary bile acids to secondary bile acids was significantly decreased. When deoxycholic acid was higher than 29.55 ug/g or lithocholic acid was higher than 0.195 ug/g, it had predictive value for clinical response. Conclusion Fecal bile acids, especially deoxycholic acid and lithocholic acid, may serve as novel biomarkers for predicting the therapeutic effect of biological agents in UC patients.

Investigation and evaluation of gastrointestinal toxicity biomarkers in rats with different sites of gastrointestinal injury

There are few reliable biomarkers for gastrointestinal toxicity, and the further identification of such markers can improve the accuracy and speed of toxicological evaluations. This study aimed to evaluate the effectiveness of several recently proposed biomarkers—plasma citrulline, fecal calprotectin, fecal bile acid, and plasma miRNAs (miR-194 and -215)—in detecting intestinal toxicity. To this end, cysteamine hydrocholoride (cysteamine, 600 or 900 mg/kg, PO), indomethacin (10 mg/kg, PO), or 2,4-Dinitrobenzenesulfonic acid hydrate (DNBS, 20 mg/kg, IR) were administered to male Wistar rats to establish models of gastric/duodenal, jejunum/ileum, or colonic damage, respectively. Both novel biomarkers and traditional toxicological parameters were evaluated in these rat models. Standard in-life observations, such as fecal properties or body weight, were inadequate for monitoring intestinal toxicity, as there were few observable changes indicative of intestinal injury, especially in the cysteamine and indomethacin models. Plasma citrulline drastically decreased in cysteamine or indomethacin-treated rats, with a milder decrease in DNBS-treated animals. Fecal total bile acids and calprotectin levels increased only in rats treated with indomethacin or DNBS, but not with cysteamine. While plasma miR-194 remained unchanged across all models, miR-215 levels decreased after cysteamine treatment. Together, these results suggest that plasma citrulline and fecal calprotectin may be effective biomarkers for monitoring intestinal injury. Fecal TBA and plasma miR-215 also show potential as useful biomarkers, but further research is needed to confirm their efficacy. Specifically, plasma citrulline is indicative of damage from the stomach to the ileum, fecal total bile acids and calprotectin are indicative of damage from the jejunum to the rectum, and plasma miR-215 is indicative of damage from the stomach and the duodenum. Integrating these novel biomarkers with standard toxicological parameters will help in predicting actual intestinal sites of damage. This integration has the potential to improve the quality of toxicological evaluations. Our findings support the use of these biomarkers in clinical settings.

Apple Polyphenol Extracts Attenuated Depressive-Like Behaviors of High-Sucrose Diet Feeding Mice by Farnesoid X Receptor-Mediated Modulation of Bile Acid Circulation within the Liver-Gut-Brain Axis.

Although the association between high-sugar diets and depression has been verified, few studies have explored the antidepressant mechanisms of apple polyphenol extracts (APE). Therefore, fifty-four C57BL/6 male mice aged 5 weeks were randomly assigned into five groups: the control group with the standard diet (CON), the constant high-sucrose diet group (HSD), the "2 + 5" alternate diet group (A-HSD), and the 500 mg/(kg·bw) APE treatment for the HSD group (APE) and the A-HSD group (A-APE), respectively. The data of hypothalamic-pituitary-adrenal (HPA) axis function and behavioral experiments confirmed the success in the establishment of depression-like mouse models in both HSD and A-HSD groups, which were significantly alleviated after APE treatment. Meanwhile, APE reduced serum levels of corticosterone and adrenocorticotrophic hormone, alleviated histopathological damage of the liver, colon, and brain, respectively, elevated the protein expressions of Occludin, ZO-1, and MUC-2, and decreased Firmicutes/Bacteroidota ratio and Dubosiella abundance with the increased microbiota of Tannerellaceae_unclassified, Muribaculum, and Lachnospiraceae_unclassified. Moreover, APE treatment reduced Farnesoid X receptor (FXR) protein levels along with the increased expressions of CYP7A1 and TGR5, lowered the contents of serum and fecal total bile acids, and modulated fecal BA compositions, particularly glycocholic acid (GCA) and isolithocholic acid (ILCA). Thus, both the constant and alternate high-sucrose diets successfully induced depression-like behaviors in mice, and APE might be a potential nutraceutical to attenuate high-sucrose diet-induced depression by regulating BAs circulation within the liver-gut-brain axis mediated by FXR.

Lactobacillus Kefir M20 Adaptation to Bile Salts: A Novel Pathway for Cholesterol Reduction.

(1) Background: This study investigated the impact of in vitro adaptations to acid and bile stress on the cholesterol-lowering activity of the probiotic Lactobacillus kefir M20. (2) Methods: Lactobacillus kefir M20 was extracted from fermented dairy products in Xinjiang, China, and isolated using MRS medium. The lactic acid bacteria were cultured for stress resistance to acid and bile salts and then gavaged into mice for animal experiments. (3) Results: The adaptation to bile stress treatment resulted in a notable enhancement of the cholesterol-lowering capacity of Lactobacillus kefir M20, with reductions of 16.5% and 33.1% in total and non-HDL cholesterol, respectively, compared to the untreated strain. Furthermore, the daily fecal total bile acid excretion was 9.2, 5.4 and 5.0 times higher in the M20-BSA group compared to the HC, M20 and M20-ASA groups, respectively. (4) Conclusions: This study suggests that targeted probiotics have the potential for application in the next generation of functional foods and probiotic formulations aimed at combating hypercholesterolemia.

Additional criteria on scintigraphic testing for diagnosis of rapid colonic transit in patients with chronic diarrhea.

Colonic transit (CT) measured by validated scintigraphy using 111In-labeled activated charcoal particles is summarized using geometric center (GC) of isotopic distribution in four colonic regions and stool at 24 and 48 h. Diagnosis of rapid CT is currently based on GC24 ≥4.4 in females and >4.7 in males, which lack sensitivity. Our aim was to evaluate, in patients with chronic diarrhea with normal CT by GC24 and GC48, the diagnostic utility of CT change (∆GC) relative to sex-matched normal values. We evaluated two adult patient cohorts: 701 clinical patients (1994-2023) with chronic diarrhea and 76 research participants with irritable bowel syndrome with diarrhea (N = 63) or bile acid diarrhea (BAD, N = 13). Results of ∆GC were compared to 220 healthy controls' 95th percentiles (%ile) (≥2.0 females and ≥2.2 males). In the research cohort, we also analyzed (Spearman correlation) colonic ∆GC with ascending colon emptying T1/2 (AC T1/2), average stool frequency and consistency based on a daily diary, total fecal bile acid (BA) concentration, and % primary BA in a single stool sample. Among 701 clinical patients with normal GC24, 160 (22.3%) had rapid CT based on ∆GC 95th %ile in health. Among 76 research participants, an additional 20.6% IBS-D and 23% BAD had rapid CT ∆GC. Younger age and absence of diabetes mellitus were predictive of rapid ∆GC. ∆GC significantly correlated with AC T1/2 and with fecal BA. ∆GC identified an additional 21%-23% patients with rapid colonic transit among patients with diarrhea and normal GC24.

Bariatric Surgery Is Associated with Lower Concentrations of Fecal Secondary Bile Acids and Their Metabolizing Microbial Enzymes: A Pilot Study.

Excess body fat elevates colorectal cancer risk. While bariatric surgery (BRS) induces significant weight loss, its effects on the fecal stream and colon biology are poorly understood. Specifically, limited data exist on the impact of bariatric surgery (BRS) on fecal secondary bile acids (BA), including lithocholic acid (LCA), a putative promotor of colorectal carcinogenesis. This cross-sectional case-control study included 44 patients with obesity; 15 pre-BRS (controls) vs. 29 at a median of 24.1months post-BRS.We examined the fecal concentrations of 11 BA by liquid chromatography and gene abundance of BA-metabolizing bacterial enzymes through fecal metagenomic sequencing. Differences were quantified using non-parametric tests for BA levels and linear discriminant analysis (LDA) effect size (LEfSe) for genes encoding BA-metabolizing enzymes. Total fecal secondary BA concentrations trended towards lower levels post- vs. pre-BRS controls (p = 0.07). Individually, fecal LCA concentrations were significantly lower post- vs. pre-BRS (8477.0 vs. 11,914.0 uM/mg, p < 0.008). Consistent with this finding, fecal bacterial genes encoding BA-metabolizing enzymes, specifically 3-betahydroxycholanate-3-dehydrogenase (EC 1.1.1.391) and 3-alpha-hydroxycholanate dehydrogenase (EC 1.1.1.52), were also lower post- vs. pre-BRS controls (LDA of - 3.32 and - 2.64, respectively, adjusted p < 0.0001). Post-BRS fecal BA concentrations showed significant inverse correlations with weight loss, a healthy diet quality, and increased physical activity. Concentrations of LCA, a secondary BA, and bacterial genes needed for BA metabolism are lower post-BRS. These changes can impact health and modulate the colorectal cancer cascade. Further research is warranted to examine how surgical alterations and the associated dietary changes impact bile acid metabolism.

Widely Targeted Lipidomics and Microbiomics Perspectives Reveal the Mechanism of Auricularia auricula Polysaccharide's Effect of Regulating Glucolipid Metabolism in High-Fat-Diet Mice.

The role of Auricularia auricula polysaccharide (AP) in the regulation of glycolipid metabolism was investigated using a high-fat-diet-induced hyperlipidemic mouse model. In a further step, its potential mechanism of action was investigated using microbiome analysis and widely targeted lipidomics. Compared to high-fat mice, dietary AP supplementation reduced body weight by 13.44%, liver index by 21.30%, epididymal fat index by 50.68%, fasting blood glucose (FBG) by 14.27%, serum total cholesterol (TC) by 20.30%, serum total triglycerides (TGs) by 23.81%, liver non-esterified fatty acid (NEFA) by 20.83%, liver TGs by 20.00%, and liver malondialdehyde (MDA) by 21.05%, and increased liver glutathione oxidase (GSH-PX) activity by 52.24%, total fecal bile acid (TBA) by 46.21%, and fecal TG by 27.16%, which significantly regulated glucose and lipid metabolism. Microbiome analysis showed that AP significantly downregulated the abundance of the Desulfobacterota phylum, as well as the genii Desulfovibrio, Bilophila, and Oscillbacter in the cecum of hyperlipidemic mice, which are positively correlated with high lipid indexes, while it upregulated the abundance of the families Eubacterium_coprostanoligenes_group and Ruminococcaceae, as well as the genii Eubacterum_xylanophilum_group, Lachnospiraceae_NK4A136_group, Eubacterium_siraeum_group, and Parasutterella, which were negatively correlated with high lipid indexes. In addition, AP promoted the formation of SCFAs by 119.38%. Widely targeted lipidomics analysis showed that AP intervention regulated 44 biomarkers in metabolic pathways such as sphingolipid metabolism and the AGE-RAGE signaling pathway in the hyperlipidemic mice (of which 15 metabolites such as unsaturated fatty acids, phosphatidylserine, and phosphatidylethanolamine were upregulated, and 29 metabolites such as phosphatidylcholine, ceramide, carnitine, and phosphatidylinositol were downregulated), thereby correcting glucose and lipid metabolism disorders.

Exposure of Mice to a PFAS Mixture and Outcomes Related to Circulating Lipids, Bile Acid Excretion, and the Intestinal Transporter ASBT.

Previous epidemiological studies have repeatedly found per- and polyfluoroalkyl substances (PFAS) exposure associated with higher circulating cholesterol, one of the greatest risk factors for development of coronary artery disease. The main route of cholesterol catabolism is through its conversion to bile acids, which circulate between the liver and ileum via enterohepatic circulation. Patients with coronary artery disease have decreased bile acid excretion, indicating that PFAS-induced impacts on enterohepatic circulation may play a critical role in cardiovascular risk. Using a mouse model with high levels of low-density and very low-density lipoprotein (LDL and VLDL, respectively) cholesterol and aortic lesion development similar to humans, the present study investigated mechanisms linking exposure to a PFAS mixture with increased cholesterol. Male and female mice were fed an atherogenic diet (Clinton/Cybulsky low fat, 0.15% cholesterol) and exposed to a mixture of 5 PFAS representing legacy, replacement, and emerging subtypes (i.e., PFOA, PFOS, PFHxS, PFNA, GenX), each at a concentration of , for 7 wk. Blood was collected longitudinally for cholesterol measurements, and mass spectrometry was used to measure circulating and fecal bile acids. Transcriptomic analysis of ileal samples was performed via RNA sequencing. After 7 wk of PFAS exposure, average circulating PFAS levels were measured at 21.6, 20.1, 31.2, 23.5, and in PFAS-exposed females and 12.9, 9.7, 23, 14.3, and in PFAS-exposed males for PFOA, PFOS, PFHxS, PFNA, and GenX, respectively. Total circulating cholesterol levels were higher in PFAS-exposed mice after 7 wk ( vs. in female mice and vs. in male mice exposed to vehicle or PFAS, respectively). Total circulating bile acid levels were higher in PFAS-exposed mice ( vs. in female mice and vs. in male mice exposed to vehicle or PFAS, respectively). In addition, total fecal bile acid levels were lower in PFAS-exposed mice ( vs. in females and vs. in males exposed to vehicle or PFAS, respectively). In the ileum, expression levels of the apical sodium-dependent bile acid transporter (ASBT) were higher in PFAS-exposed mice. Mice exposed to a PFAS mixture displayed higher circulating cholesterol and bile acids perhaps due to impacts on enterohepatic circulation. This study implicates PFAS-mediated effects at the site of the ileum as a possible critical mediator of increased cardiovascular risk following PFAS exposure. https://doi.org/10.1289/EHP14339.

Lactobacillus delbrueckii Ameliorated Blood Lipids via Intestinal Microbiota Modulation and Fecal Bile Acid Excretion in a Ningxiang Pig Model.

Lactobacillus delbrueckii intervention can regulate body lipid metabolism, but the underlying mechanism remains unclear. Our study investigated the effects of L. delbrueckii on serum lipid levels, tissular fat metabolism and deposition, bile acid metabolism, and gut microbiota in Ningxiang pigs. Ninety-six pigs were divided into two groups and fed basal diets containing either 0 (CON) or 0.1% L. delbrueckii (LD) for 60 days. Dietary L. delbrueckii promoted fecal total bile acid (TBA) excretion and increased hepatic enzyme activities related to cholesterol and bile synthesis but decreased hepatic and serum lipid concentrations. L. delbrueckii downregulated gene expression associated with fatty acid synthesis but upregulated gene expression related to lipolysis and β-fatty acid oxidation in liver and subcutaneous fat. L. delbrueckii elevated gut Lactobacillus abundance and colonic short-chain fatty acid (SCFA)-producing bacteria but declined the abundance of some pathogenic bacteria. These findings demonstrated that L. delbrueckii modulated intestinal microbiota composition and facilitated fecal TBA excretion to regulate hepatic fat metabolism, which resulted in less lipid deposition in the liver and reduced levels of serum lipids.

Polysaccharides of Aspergillus cristatus attenuate obesity by regulating gut microbiota and gut microbiota-related metabolites

Golden-flower fungus, the only dominant microorganism determining the Fu-brick tea quality through fermentation and the important microbe in Liupao tea, is considered a potential probiotic fungus based on its anti-obesity effect. However, the classification of golden-flower fungi is still controversial; the anti-obesity effect of golden-flower fungus polysaccharides remains unknown. In this study, we identify a golden-flower strain as Aspergillus cristatus based on morphological characteristics and multigene phylogeny analysis, which resolves the controversy of classification. Moreover, we find A. cristatus polysaccharides (ACPS) attenuate obesity in rats. ACPS modulate gut bacterial composition, in which Akkermansia, Akkermansia muciniphila, Bacteroides, Romboutsia, Blautia, and Desulfovibrio are considered the core microbes regulated by ACPS. ACPS increase fecal total short-chain fatty acid content and serum, hepatic, and fecal total bile acid content. Furthermore, ACPS-induced gut microbiota alteration plays a causal role in the protection from obesity, according to a fecal transplantation experiment. Thus, ACPS ameliorate obesity by regulating gut microbiota and gut microbiota-related metabolites.

The supplementation of the multi-strain probiotics WHHPRO™ alleviates high-fat diet-induced metabolic symptoms in rats via gut-liver axis.

Metabolic syndrome (MS) has emerged as one of the major global health concerns, accompanied by a series of related complications, such as obesity and type-2 diabetes. The gut-liver axis (GLA) is a bidirectional communication between the gut and the liver. The GLA alterations have been revealed to be closely associated with the development of MS. Probiotics within Lactobacillus and Bifidobacterium confer beneficial effects on improving MS symptoms. WHHPRO™ is a mixture of four probiotic strains, with potential MS-improving abilities. This study aimed to investigate the effects of WHHPRO™ on MS symptoms using a high-fat diet (HFD) rat model. Oral administration of WHHPRO™ for 12 weeks improved glucose tolerance, blood lipid, body weight, and liver index in HFD rats. WHHPRO™ shaped the gut microbiome composition by increasing the abundance of Lactobacillus and Akkermansia and normalized the reduced SCFA levels in HFD rats. Besides, WHHPRO™ modulated the fecal bile acids (BAs) profile, with decreased levels of T-b-MCA and 12-KDCA and increased levels of LCA and ILCA. Meanwhile, WHHPRO™ increased total unconjugated BAs in feces and liver and reduced the accumulation of total hepatic BA pool size in HFD rats. Moreover, WHHPRO™ reversed the expression of genes associated with impaired BA metabolism signaling in the ileum and liver. Our findings suggest that WHHPRO™ exerted beneficial effects on improving MS symptoms, involving the modulation of the gut microbiome composition, SCFAs, and the FXR-FGF15 signaling along the GLA. Supplementation of WHHPRO™ may serve as a novel strategy for improving MS symptoms.

Elobixibat improves rectal sensation in patients with chronic constipation aged ≥60 years: a randomised placebo-controlled study

ObjectiveHigh rectal sensory thresholds (RSTs) are associated with chronic constipation (CC), especially in older patients. Bile acids (BAs) affect the RSTs of healthy individuals. Here, we aimed to investigate the...

OR22-01 Sex Differences In Enterohepatic Circulation Mediated By Hepatic FXR And SHP Depletions In Mice

Abstract Disclosure: F. Reichardt: None. C. Galuke: None. S. Anakk: None. Bile acids are transported via the portal vein to the liver after their absorption through the distal intestine mucosa. In hepatocytes, they activate the nuclear receptors, Farnesoid-X-receptor (FXR) and Small Heterodimer Partner (SHP), which exert negative feedback on bile acids synthesis. The aim of this project is to decipher how hepatic FXR/SHP deletion impact BA composition, enterohepatic circulation, and its cross talk with the gut microbiota. Enterohepatic circulation was investigated by measuring total bile acids in intestinal, hepatic tissues and fecal tissues and in portal and systemic blood, using 3-5 months-old fed female and male wildtype (WT) and LDKO (liver specific FXR/SHP depletions) mice. We also examined if intestinal dysmotility mediated the alteration in bile acids absorption by following methylene blue dye progression in overnight fasted WT and LDKO mice. Portal and systemic total bile acids concentrations were higher in LDKO mice compared to WT, despite of no significant change in hepatic and intestinal levels. Sex differences were seen only in LDKO mice with higher systemic and portal concentrations in females compared to males. Intestinal transit time and fecal total bile acids were equivalent between all mice. Intriguingly, we observed that portal bile acids levels correlated to the liver weight to body weight ratio and to cecum weight to body weight ratio, suggesting that bile acids alterations within the enterohepatic loop could be associated to cecal dysbiosis. These preliminary findings highlight altered BA recirculation in LDKO mice compared to WT, but also between females and males LDKO. We hypothesize that these sex-specific modifications are associated with intestinal dysbiosis impacting bile acid compositions, and to test this we will be analyzing the influence of sex, and BA composition on the microbiome. Further investigations using fasted or HFD-fed LDKO and WT mice will help us to better understand the role of hepatic FXR and SHP in bile acids circulation between intestine and liver. Acknowledgement: University of Illinois Urbana-Champaign, American Cancer Society and Cancer Center at Illinois Seed grant Presentation: Saturday, June 17, 2023

Long-term effects on liver metabolism induced by ceftriaxone sodium pretreatment

Ceftriaxone is an emerging contaminant due to its potential harm, while its effects on liver are still need to be clarified. In this study, we first pretreated the 8-week-old C57BL/6J mice with high dose ceftriaxone sodium (Cef, 400 mg/mL, 0.2 mL per dose) for 8 days to prepare a gut dysbiosis model, then treated with normal feed for a two-month recovery period, and applied non-targeted metabolomics (including lipidomics) to investigate the variations of fecal and liver metabolome, and coupled with targeted determination of fecal short-chain fatty acids (SCFAs) and bile acids (BAs). Lastly, the correlations and mediation analysis between the liver metabolism and gut metabolism/microbes were carried, and the potential mechanisms of the mal-effects on gut-liver axis induced by Cef pretreatment were accordingly discussed. Compared to the control group, Cef pretreatment reduced the rate of weight gain and hepatosomatic index, induced bile duct epithelial cells proliferated around the central vein and appearance of binucleated hepatocytes, decreased the ratio of total branching chains amino acids (BCAAs) to total aromatic amino acids (AAAs) in liver metabolome. In fecal metabolome, the total fecal SCFAs and BAs did not change significantly while butyric acid decreased and the primary BAs increased after Cef pretreatment. Correlation and mediation analysis revealed one potential mechanism that Cef may first change the intestinal microbiota (such as destroying its normal structure, reducing its abundance and the stability of the microbial network or certain microbe abundance like Alistipes), and then change the intestinal metabolism (such as acetate, caproate, propionate), leading to liver metabolic disorder (such as spermidine, inosine, cinnamaldehyde). This study proved the possibility of Cef-induced liver damage, displayed the overall metabolic profile of the liver following Cef pretreatment and provided a theoretical framework for further research into the mechanism of Cef-induced liver damage.

Altered gut microbiota–host bile acid metabolism in IBS-D patients with liver depression and spleen deficiency pattern

BackgroundDysregulation of gut microbiota–host bile acid (BA) co-metabolism is a critical pathogenic factor of diarrhea-predominant irritable bowel syndrome (IBS-D). Traditional Chinese Medicine (TCM), instructed by pattern differentiation, is effective in treating IBS-D, in which liver depression and spleen deficiency (LDSD) is the most prevalent pattern. Still, it is unclear the linkage between the LDSD pattern and the BA metabolic phenotype.PurposeThis study aimed to uncover the biological basis of the LDSD pattern from the BA metabolic perspective.MethodsPatients with IBS-D completed questionnaires regarding the irritable bowel severity scoring system (IBS-SSS), stool frequency, Stool Bristol scale, and Self-Rating Scales of mental health. Fasting blood and morning feces were collected to analyze the gut metagenome and BA-related indices/metabolites.ResultsIBS-D patients with LDSD had a higher incidence of BA overexcretion (41% vs. 23% non-LDSD) with significant elevations in fecal total BAs and serum BA precursor 7α-hydroxy-4-cholesten-3-one levels. Compared to controls or non-LDSD patients, LDSD patients had a featured fecal BA profile, with higher proportions of deoxycholic acid (DCA), 7-ketodeoxycholic acid, and lithocholic acid. It is consistent with the BA-metabolizing genomic changes in the LDSD gut microbiota characterized by overabundances of 7-dehydroxylating bacteria and BA-inducible genes (baiCD/E/H). The score of bowel symptoms (stool frequency and abdominal pain) showing greater severity in the LDSD pattern were positively correlated with bai-expressing bacterial abundances and fecal DCA levels separately.ConclusionWe clarified a differed BA metabolic phenotype in IBS patients with LDSD, which closely correlates with the severity of bowel symptoms. It demonstrates that gut microbiota and host co-metabolism of BAs would provide crucial insight into the biology of the LDSD pattern and its internal relationship with IBS progression.

Stigmasterol Protects Against Steatohepatitis Induced by High-Fat and High-Cholesterol Diet in Mice by Enhancing the Alternative Bile Acid Synthesis Pathway

BackgroundHepatic cholesterol accumulation is a significant risk factor in the progression of nonalcoholic fatty liver disease (NAFLD) to steatohepatitis. However, the precise mechanism by which stigmasterol (STG) mitigates this process remains unclear. ObjectivesThis study aimed to investigate the potential mechanism underlying the protective effect of STG in mice with NAFLD progressing to steatohepatitis while being fed a high-fat and high-cholesterol (HFHC) diet. MethodsMale C57BL/6 mice were fed an HFHC diet for 16 wk to establish the NAFLD model. Subsequently, the mice received STG or a vehicle via oral gavage while continuing the HFHC diet for an additional 10 wk. The study evaluated hepatic lipid deposition and inflammation as well as the expression of key rate-limiting enzymes involved in the bile acid (BA) synthesis pathways. BAs in the colonic contents were quantified using ultra-performance liquid chromatography-tandem mass spectrometry. ResultsCompared with the vehicle control group, STG significantly reduced hepatic cholesterol accumulation (P < 0.01) and suppressed the gene expression of NLRP3 inflammasome and interleukin-18 (P < 0.05) in the livers of HFHC diet-fed mice. The total fecal BA content in the STG group was nearly double that of the vehicle control group. Additionally, the administration of STG increased the concentrations of representative hydrophilic BAs in the colonic contents (P < 0.05) along with the upregulation of gene and protein expression of CYP7B1 (P < 0.01). Furthermore, STG enhanced the α-diversity of the gut microbiota and partially reversed the alterations in the relative abundance of the gut microbiota induced by the HFHC diet. ConclusionsSTG mitigates steatohepatitis by enhancing the alternative pathway for BA synthesis.

Intermittent fasting alleviates non-alcoholic steatohepatitis by regulating bile acid metabolism and promoting fecal bile acid excretion in high-fat and high-cholesterol diet fed mice.

Intermittent fasting (IF) has a protective role across a wide range of chronic disorders, including obesity, diabetes and cardiovascular disease, but its protection against non-alcoholic steatohepatitis (NASH) is still lacking. This study sought to investigate how IF alleviates NASH by regulating gut microbiota and bile acids (BAs) composition. Male C57BL/6 mice were fed a high-fat and high-cholesterol (HFHC) diet for 16 weeks to establish a NASH model. Mice then continued HFHC feeding and were treated with or without every other day fasting for 10 weeks. Hepatic pathology was assessed using hematoxylin-eosin staining. Gut microbiota of the cecum were profiled using 16S rRNA gene sequencing and the levels of BAs in serum, colon contents, and feces were measured using UPLC-MS/MS. Results indicated that IF significantly decreased murine body weight, insulin resistance, hepatic steatosis, ballooning, and lobular inflammation. IF reshaped the gut microbiota, reduced the accumulation of serum BAs, and increased total colonic and fecal BAs. Moreover, IF increased the expression of cholesterol 7α-hydroxylase 1 in liver, but decreased the expressions of both farnesoid-X-receptor and fibroblast growth factor 15 in the ileum. IF alleviated NASH by regulating bile acid metabolism and promoting fecal bile acid excretion. This article is protected by copyright. All rights reserved.

Chronic corticosterone exposure disrupts hepatic and intestinal bile acid metabolism in chicken.

Chronic stress leads to a high circulating level of glucocorticoids, which disrupts lipid metabolism and causes non-alcoholic fatty liver disease in mice and humans. Meanwhile, bile acid (BA), a class of metabolites initially synthesized in the liver and further metabolized by gut microbiota, plays a vital role in lipid metabolism. This study aimed to investigate the effects of glucocorticoids on BA metabolism and gut microbiota in chickens. In this study, 35-day-old chickens were injected with 4 mg/kg/day corticosterone (Cort) for 14 days to simulate chronic stress. Cort treatment significantly increased the triglyceride contents in the plasma and the liver. HE and oil-red staining showed that Cort treatment induced fatty liver in chickens. Meanwhile, Cort exposure downregulated total bile acid (TBA) content in the liver while increasing the TBA in feces. UPLC-HRMS results showed that Cort exposure significantly decreased the hepatic levels of CDCA, T-alpha-MCA, and T-beta-MCA. Moreover, Cort exposure significantly reduced the expression of genes related to BA synthesis (CYP8B1 and CYP27A1), conjugation (BACS), and regulation (KLβ and FGFR4). 16s sequencing results showed that Cort treatment significantly decreased the amount of Lachnospiraceae, Eisenbergiella, Blautia, and Eubacterium and increased the abundance of Barnesiella, Lactobacillus, and Helicobacter. Spearman correlation analysis showed a significant positive correlation between fecal TBA and the abundance of Lactobacillales, Lactobacillus, and Barnesiella. In comparison, TBA in the liver was positively correlated with Eubacterium, and negatively correlated with Helicobacter. In summary, chronic Cort exposure disrupts hepatic and intestinal bile acid metabolism inducing gut microbiome dysbiosis, which might associate with the development of fatty liver in chickens.

Dietary Soybean Protein Decreases Plasma Taurine in Cats

Commercial dry and canned diets fed to cats cause ∼two- and fourfold increase in the taurine requirement, respectively, as compared with that observed for purified diets. In two experiments, the effect of source and level of protein and fiber in the diet on the concentration of taurine in plasma and whole blood of cats was studied. All diets contained 1 g taurine/kg dry matter. When a casein-based diet containing either 25% or 50% protein was given to cats for 6 wk, no difference in plasma taurine concentration was observed; however, substituting soybean protein for casein resulted in a significant (P < 0.01) decrease in plasma taurine concentration of cats in the 50% soybean protein group, but not in the 25% soybean protein group. In Experiment 2, the food intake of cats was limited [26 g dry matter/(kg body weight·d)], and the protein was 30 or 60% of the diet. Cats fed 60% soybean protein or casein diets had significantly lower plasma taurine concentrations than cats fed a 30% casein diet, with the 60% soybean protein diet causing the greater decrease. There was no effect of either 2 or 4% soybean fiber on plasma taurine concentration as compared with the same diet without the added fiber. The taurine concentration in plasma was higher (P < 0.05) in male cats than in female cats. Protein source, amount in the diet and gender did not affect the whole blood taurine concentration. Cats given diets containing 60% casein or soybean protein diets excreted a greater amount of fecal total bile acid and total taurine than cats given a 30% casein diet. Cats with higher plasma concentrations of taurine excreted a greater amount of free taurine in urine, and a lesser amount of taurine and bile acids in feces. These results show that although protein source (soybean protein) and the quantity in the diet have a significant effect on the excretion pattern of taurine by cats, these effects are not sufficient to account for the marked increase in the taurine requirement found when canned heat-processed diets are fed.

Cholestasis impairs gut microbiota development and bile salt hydrolase activity in preterm neonates

ABSTRACT Cholestasis refers to impaired bile flow from the liver to the intestine. In neonates, cholestasis causes poor growth and may progress to liver failure and death. Normal bile flow requires an intact liver-gut-microbiome axis, whereby liver-derived primary bile acids are transformed into secondary bile acids. Microbial bile salt hydrolase (BSH) enzymes are responsible for the first step, deconjugating glycine- and taurine-conjugated primary bile acids. Cholestatic neonates often are treated with the potent choleretic bile acid ursodeoxycholic acid (UDCA), although interactions between UDCA, gut microbes, and other bile acids are poorly understood. To gain insight into how the liver-gut-microbiome axis develops in extreme prematurity and how cholestasis alters this maturation, we conducted a nested case-control study collecting 124 stool samples longitudinally from 24 preterm infants born at mean 27.2 ± 1.8 weeks gestation and 946 ± 249.6 g, half of whom developed physiologic cholestasis. Samples were analyzed by whole metagenomic sequencing, in vitro BSH enzyme activity assays optimized for low biomass fecal samples, and quantitative mass spectrometry to measure the bile acid metabolome. In extremely preterm neonates, acquisition of the secondary bile acid biosynthesis pathway and BSH genes carried by Clostridium perfringens are the most prominent features of early microbiome development. Cholestasis interrupts this developmental pattern. BSH gene abundance and enzyme activity are profoundly reduced in cholestatic neonates, resulting in decreased quantities of unconjugated bile acids. UDCA restores total fecal bile acid levels in cholestatic neonates, but this is due to a 522-fold increase in fecal UDCA. A majority of bile acids in early development are atypical positional and stereo-isomers of bile acids. We report novel associations linking isomeric bile acids and BSH activity to neonatal growth trajectories. These data highlight deconjugation of bile acids as a key microbial function that is acquired in early neonatal development and impaired by cholestasis.