Dairy Product Intake Alters the Correlations between Circulating Bile Acids and Short-Chain Fatty Acids with the Bacterial Taxa Roseburia, Faecalibacterium, Flavonifractor, and Verrucomicrobia

Bile acids regulate glucose homeostasis and lipid metabolism. Further, the levels of bile acids can be influenced by the intake of dairy products. Although the serum proteome can provide information on the biological pathways associated with different metabolites, it is unknown whether the intake of dairy modifies such associations between bile acids and the proteome. The objectives of this study were to examine plasma bile acid profiles, find the correlations between bile acids and lipid as well as glycemic markers, and to uncover the correlation between bile acids and proteins after high dairy (HD) and adequate dairy (AD) intake among 25 overweight individuals with hyperinsulinemia. In this randomized crossover-trial study, hyperinsulinemia adults were randomized to both HD (≥4 servings/day) and AD (≤2 servings/day) for 6 weeks. Measurements and analyses were performed on before- as well as after- AD and HD conditions. The results indicated that plasma 7α-hydroxy-4-cholesten-3-one (7AC4) increased after HD in comparison with before HD intake (p = 0.03). After adjusting for BMI, age, and sex, 7AC4 positively correlated with triglyceride levels in the pre-AD (r = 0.44; p = 0.03) and post-HD (r = 0.42; p = 0.04). Further, 7AC4 correlated positively with proteins associated with high-density lipoprotein particle remodeling pathway and reverse cholesterol transport only after HD consumption. Thus, the consumption of higher dairy intake modifies the association between 7AC4-a biomarker for bile acid synthesis-and serum proteins involved in cholesterol clearance. Overall, higher dairy consumption may have a positive effect on cholesterol metabolism in subjects at risk of type 2 diabetes.

What Can We Learn From Mouse Models About Bile Acid-Mediated Changes After Bariatric Surgery?

The aim of the study was to develop a method for fast and reliable diagnosis of peroxisomal diseases and to facilitate differential diagnosis of cholestatic hepatopathy. For the quantification of bile acids and their conjugates as well as C(27) precursors di- and trihydroxycholestanoic acid (DHCA, THCA), in small pediatric blood samples we combined HPLC separation on a reverse-phase C18 column with ESI-MS/MS analysis in the negative ion mode. Analysis was done with good precision (CV 3,7%-11.1%) and sufficient sensitivity (LOQ: 11-91 nmol/L) without derivatization. Complete analysis of 17 free and conjugated bile acids from dried blood spots and 10 microL serum samples, respectively, was performed within 12 min. Measurement of conjugated primary bile acids plus DHCA and THCA as well as ursodeoxycholic acid was done in 4.5 min. In blood spots of healthy newborns, conjugated primary bile acids were found in the range of 0.01 to 2.01 micromol/L. Concentrations of C(27) precursors were below the detection limit in normal controls. DHCA and THCA were specifically elevated in cases of peroxysomal defects and one Zellweger patient.

553-P: Changes in Circulating Bile Acids and the Improvements in Glucose and Insulin Metabolism in Response to Weight-Loss Diets: The POUNDS Lost Trial

Are Proton Pump Inhibitors Affecting Intestinal Microbiota Health?

To evaluate the effects of high dairy (HD) (≥4 servings/day), compared to adequate dairy (AD) (2-3 servings/day as per Canada's Food Guide for Healthy Eating (2007)), on blood pressure (BP) and measures of arterial stiffness in hyperinsulinemic subjects. In this cross-over clinical trial, hyperinsulinemic adults were randomized to AD and HD for 6 weeks. Anthropometric, glycemic, and lipid parameters were analyzed and dietary intake was evaluated; BP, carotid-femoral pulse wave velocity, augmentation index, and measures of arterial stiffness were assessed. Twenty-seven participants completed the study. Dairy intake was 2.2±1.2 servings/day during AD. In addition, lower total and low-density lipoprotein (LDL) cholesterol were observed without significant change in BP or arterial stiffness between before and after AD. During HD, the subjects consumed 5.8±1.9 servings/day of dairy products, providing a higher intake of protein, saturated fat, calcium, phosphorus, sodium, and potassium compared to the baseline diet. After the HD, subjects had higher body fat, fasting insulin, homeostatic model assessment for insulin resistance (HOMA-IR) index, and triglycerides without altering BP or arterial stiffness compared to before HD. Overall, adequate or high intake of total dairy did not modify BP or arterial stiffness in hyperinsulinemic adults after 6 weeks.

Background & AimsDysregulated bile acid (BA) homeostasis has been implicated in the initiation and progression of cholangiocarcinoma (CCA). The aim of this study was to investigate the roles of circulating and tumor BAs, oxysterols, short-chain fatty acids (SCFAs), transcriptomic changes, and stool microbiota composition in CCA, and their potential diagnostic and therapeutic implications.MethodsWe used ultra-performance liquid chromatography-tandem mass spectrometry to quantify BAs, oxysterols, and SCFAs in serum from patients with benign focal nodular hyperplasia (n = 27), primary sclerosing cholangitis (PSC; n = 20), intrahepatic CCA (iCCA; n = 29), and extrahepatic CCA (eCCA; n = 35), and in tumor and adjacent non-tumor iCCA (n = 30) and eCCA (n = 26) tissues. Publicly available liver transcriptome and gut microbiome datasets were analyzed to assess BA metabolic pathway activity and related gene expression profiles.ResultsTotal primary conjugated BA levels and the taurine-to-glycine ratio of conjugated BAs were significantly elevated in the serum of patients with PSC and CCA compared to controls with focal nodular hyperplasia (p <0.05). Transcriptomic analysis revealed a significant downregulation of GLYAT and BAAT, key genes involved in glycine and taurine conjugation, in PSC and CCA (p <0.05). Hepatic oxysterol levels were increased concomitantly with BAs in patients with CCA. Among SCFAs, butyric acid was positively correlated with conjugated BAs in the serum of patients with iCCA, whereas acetic acid was negatively correlated with BAs in the serum of patients with non-PSC-eCCA (p <0.05). Conjugated BAs were positively correlated with carbohydrate antigen 19-9 levels in patients with iCCA and non-PSC-eCCA.ConclusionsProfound alterations in serum and tissue levels of primary and taurine-conjugated BAs occur during cholangiocarcinogenesis. Further elucidation of the mechanisms regulating BA and oxysterol metabolism in CCA may offer new avenues for diagnosis and therapy.Impact and implicationsCholangiocarcinomas (CCAs) are aggressive malignancies with limited therapeutic options. Although CCA cells exhibit distinct metabolic profiles, investigating their regulation through the enterohepatic axis remains challenging. In this study, targeted metabolomics was used to analyze bile acid (BA) profiles in serum and liver tissue, serum short-chain fatty acids, and hepatic oxysterol levels in patients with intrahepatic and extrahepatic CCA, compared to controls with focal nodular hyperplasia and primary sclerosing cholangitis. Liver transcriptome analysis revealed differentially expressed genes involved in BA metabolism in patients with primary sclerosing cholangitis and CCA. Correlations were also examined between BAs, oxysterols, short-chain fatty acids, clinical features, and microbiome components implicated in CCA development. These findings provide new insights into BA dysregulation in CCA and establish a foundation for the development of novel diagnostic biomarkers and therapeutic strategies.

We present a method using a combination of enzymatic deconjugation and targeted LC-multiple reaction monitoring (MRM)-MS analysis for analyzing all common bile acids (BAs) in piglet urine, and in particular, for detecting conjugated BAs either in the absence of their standards, or when present in low concentrations. Initially, before enzymatic deconjugation, 19 unconjugated BAs (FBAs) were detected where the total concentration of the detected FBAs was 9.90 μmol/l. Sixty-seven conjugated BAs were identified by LC-MRM-MS analysis before and after enzymatic deconjugation. Four enzymatic assays were used to deconjugate the BA conjugates. FBAs in urine after cholylglycine hydrolase/sulfatase treatment were 33.40 μmol/l, indicating the urinary BAs were comprised of 29.75% FBAs and 70.25% conjugated BAs in single and multiple conjugated forms. For the conjugates in single form, released FBAs from cholylglycine hydrolase deconjugation indicated that the conjugates with amino acids were 14.54% of urinary BAs, 16.27% glycosidic conjugates were found by β-glucuronidase treatment, and sulfatase with glucuronidase inhibitor treatment liberated FBAs that constituted 16.67% of urinary BAs. Notably, chenodeoxycholic acid (CDCA) was initially detected only in trace amounts in urine, but was found at significant levels after the enzymatic assays above. These results support that CDCA is a precursor of γ-muricholic acid in BA biosynthesis in piglets.

Introduction: Bile acids (BAs) are synthesized in the liver from cholesterol, and gut microbiota transform the host-derived primary BAs into secondary BAs in the intestine. Emerging evidence suggests that different types of circulating BAs may play pivotal roles in regulating energy metabolism and body adiposity. Hypothesis: We comprehensively examined whether changes in different BA subtypes after consuming weight-loss diets were associated with improvements in energy metabolism and body adiposity among patients with obesity. Methods: This study included 551 overweight and obese adults who participated in a 2-year weight-loss dietary intervention, the POUNDS Lost trial. Blood levels of 14 types of BAs (primary and secondary unconjugated BAs and their taurine-/glycine-conjugates) were measured at baseline and 6 months after the intervention; changes in BAs from baseline to 6 months after the intervention were calculated. We evaluated changes in resting energy expenditure, weight, and waist circumference. Also, body composition was assessed by the dual-energy X-ray absorptiometry (DEXA) scans, and fat distribution was assessed by computed tomography (CT) scans. Results: At baseline, higher primary and secondary BAs were related to greater degrees of adiposity and energy expenditure. At 6 months after the intervention, greater decreases in primary BAs (cholic acid [CA] and chenodeoxycholic acid) and secondary BAs (deoxycholic acid [DCA] and lithocholic acid [LCA]) and their conjugated subtypes (except for glycolithocholic acid) were significantly associated with more decreases in weight and waist circumference at 6 months after the intervention (P values after controlling for the multiple testing, P FDR &lt;0.05). Greater reductions in the primary BAs (both unconjugated and conjugated types) and secondary BAs (DCA and its taurine-/glycine-conjugated forms) were also significantly ( P FDR &lt;0.05) associated with more decreases in resting energy expenditure at 6 months. We found that reductions in two BA subtypes, glycocholic acid (GCA) and glycoursodeoxycholic acid (GUDCA), were consistently and significantly associated with improvements in energy metabolism, general and central adiposity, as well as body fat composition and visceral adipose tissue mass. Further, the initial (6-month) changes in several primary and secondary BAs (including GCA and GUDCA) were significantly predictive of the long-term successful weight loss (weight loss of more than 5% loss from the initial weight) at 2 years. Conclusions: Weight-loss diet-induced changes in circulating various BAs may be involved in improving general and central adiposity and energy metabolism. Changes in specific BA subtypes would be potential targets for improving regional adiposity and achieving successful weight-loss among patients with obesity.

Exclusive enteral nutrition (EEN) is a first-line therapy to induce remission in paediatric Crohn’s disease (CD). However, many patients will relapse upon resuming normal diet and there are no validated measures to determine subgroups of patients who will benefit most from EEN. We recently demonstrated that the certain compositional features of gut microbiome are associated with relapse following EEN. Microbiome composition can impact the balance of intestinal bile acids (BA), which have important antimicrobial and immune functions. The goal of this study was to analyse the relationship between intestinal BA composition and response to EEN in paediatric CD. We performed faecal BA analysis on a biorepository of stool samples from 13 paediatric CD patients who were treated with EEN for 12 weeks and achieved remission as defined by wPCDAI <12.5. All patients received maintenance therapy with an immunomodulator. Of these 13 patients, 7 sustained remission (SR) and 6 relapsed within 3 months of EEN cessation (non-sustained remission (NSR)). Faecal BA quantification was performed by the Sick Kids Analytical Facility for Molecules (AFBM) by liquid chromatography tandem mass spectrometry (LC-–MS-MS) using the Biocrates Life Sciences Bile Acids Kit according to the manufacturer’s instructions. For samples with BA abundance above the limit of detection, the missing data were imputed using area ratios relative to internal standards. BA concentrations were not normally distributed according to D’Agostino-Pearson test, so data are presented as median [range] and compared between groups using the Mann–Whitney U test. NSR patients had significantly lower levels of secondary BA (deoxycholic acid (DCA) and lithocholic acid (LCA) prior to starting EEN: median LCA 1 [1–4] pmol/mg vs. 1976 [19–3163] pmol/mg (p < 0.05) and median DCA 2 [1–5] pmol/mg vs. 2605 [29–4288] pmol/mg (p < 0.05). NSR patients also exhibited higher levels of primary BA (cholic acid (CA) and chenodeoxycholic acid (CDCA)) at baseline and Week 12, although this was not significant. The ratio of primary to secondary BAs was profoundly increased in NSR patients compared with SR patients: median 318.4 [0.926–642.1] (p < 0.05) vs. median 0.005 [0.002–0.059]. Levels of primary and secondary BA did not change significantly over the course of EEN in either group, although secondary BA concentrations were slightly increased in NSR patients by Week 12 relative to baseline. We demonstrate that primary and secondary BA compositions in stool differed between patients who sustained remission following EEN vs. those who relapsed. BA profiling may be a useful microbiome metabolic marker to identify patients who will sustain remission longer following EEN therapy.

Urinary Bile Acid Profile of Newborns Born by Cesarean Section Is Characterized by Oxidative Metabolism of Primary Bile Acids: Limited Roles of Fetal-Specific CYP3A7 in Cholate Oxidations

BackgroundThe relationship between circulating bile acids (BAs) and kidney function among patients with type 2 diabetes is unclear. We aimed to investigate the associations of circulating concentrations of BAs, particularly individual BA subtypes, with chronic kidney disease (CKD) in patients of newly diagnosed type 2 diabetes.MethodsIn this cross-sectional study, we included 1234 newly diagnosed type 2 diabetes who participated in an ongoing prospective study, the Dongfeng-Tongji cohort. Circulating primary and secondary unconjugated BAs and their taurine- or glycine-conjugates were measured using ultraperformance liquid chromatography-tandem mass spectrometry. CKD was defined as eGFR < 60 ml/min per 1.73 m2. Logistic regression model was used to compute odds ratio (OR) and 95% confidence interval (CI).ResultsAfter adjusting for multiple testing, higher levels of total primary BAs (OR per standard deviation [SD] increment: 0.78; 95% CI: 0.65–0.92), cholate (OR per SD: 0.78; 95% CI: 0.66–0.92), chenodeoxycholate (OR per SD: 0.81; 95% CI: 0.69–0.96), glycocholate (OR per SD: 0.81; 95% CI: 0.68–0.96), and glycochenodeoxycholate (OR per SD: 0.82; 95% CI: 0.69–0.97) were associated with a lower likelihood of having CKD in patients with newly diagnosed type 2 diabetes. No significant relationships between secondary BAs and odds of CKD were observed.ConclusionsOur findings showed that higher concentrations of circulating unconjugated primary BAs and their glycine-conjugates, but not taurine-conjugates or secondary BAs, were associated with lower odds of having CKD in patients with type 2 diabetes.

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder. High bile acid (BA) profiles have been associated with abdominal pain symptoms, mucosal inflammation, and diarrhea in a subgroup of those with IBS. The purpose of this study was to compare: 1) fecal primary and secondary BAs in women with and without IBS; and 2) symptoms, gut microbiome, and diet between women with high and normal BAs (i.e., similar to healthy [HC] women). Women (ages 18-45) with IBS and HCs were recruited from healthcare providers or the community. Participants kept a 28-day symptom diary, completed a 3-day food journal, and collected a stool sample for microbiome analysis (16 S rRNA gene sequencing). Primary and secondary BA levels were determined by mass spectrometry. Primary BAs did not differ between IBS (n = 45) and HC (n = 28) groups; women with IBS had significantly increased conjugated secondary BAs (glycodeoxycholic acid [p = 0.006], taurodeoxycholic acid [p = 0.006], and glycolithocholic acid [p = 0.01]). Sixty percent of women with IBS had normal BAs whereas 40% had high BAs. Women with high fecal BAs were predominantly IBS-Diarrhea or IBS-Mixed and consumed less fiber and vegetable protein and more animal protein compared to women with IBS whose fecal BAs levels were comparable to HCs. Those with high conjugated secondary fecal BAs also had a greater Firmicutes/Bacteroidetes ratio, less abundance of phylum Bacteroidetes and genus Gemmiger, and more abundance of family Erysipelotrichaceae compared to IBS women with normal BAs. Determination of fecal BA levels provides additional insights into pathophysiological links between diet and microbiome in IBS.

Circulating bile acids, bile acid receptor polymorphisms, and risk of chronic kidney disease among individuals with newly diagnosed type 2 diabetes: a prospective study.

Background: Bile acids are synthesized from cholesterol in the liver and play pivotal roles in nutrient absorption and metabolic regulation. Altered bile acid metabolism is related to dyslipidemia, and microRNA-34a (miR-34a) may play a pivotal role in the treatment of lipid homeostasis by regulating the bile acid biosynthesis. Hypothesis: We investigated whether weight-loss diet-induced changes in primary and secondary bile acids were associated with the improvements in lipid profiles. We also tested the role of circulating miR-34a in the altered bile acid metabolism in adults with overweight and obesity. Methods: A total of 520 participants of a weight-loss dietary intervention (the POUNDS Lost trial) with data on bile acids and miR-34a were included in the present analysis. Circulating levels of miR-34a and bile acid subtypes (primary and secondary unconjugated bile acids and their taurine-/glycine-conjugates) were measured at baseline and 6 months after the intervention. Outcome measurements were improvements in lipids (triglycerides and cholesterol) in response to the interventions. Results: At baseline, higher levels of primary bile acids (chenodeoxycholate (CDCA), glycocholate (GCA), taurocholate (TCA), and glycochenodeoxycholate (GCDCA) were associated with elevated levels of triglycerides ( P FDR &lt;0.05). Greater decreases in the primary bile acid subtypes (CDCA, GCA, TCA, GCDCA, and taurochenodeoxycholate [TCDCA]) in response to the interventions were significantly associated with larger reductions of triglycerides at 6 months ( P FDR &lt;0.05 for all). Decreases in secondary bile acids (deoxycholate and its conjugated forms) also showed significant associations with decreases in triglycerides. Similarly, reductions of total cholesterol at 6 months were associated with decreases in the primary (such as GCA, GCDCA, TCDCA) and secondary bile acid subtypes. We found that greater levels of miR-34a at baseline were related to higher levels of triglycerides at baseline (p=0.038) and higher levels of primary bile acids (such as CA, CDCA, GCA, and TCA [PFDR &lt;0.05 for all]) but not with the secondary bile acids at baseline. Further, weight-loss diet-induced changes in miR-34a were positively correlated with changes in the primary bile acid subtypes (CDCA, GCA, and GCDCA). Conclusions: Changes in the specific primary and secondary bile acid subtypes were related to the improvements in lipid profiles in response to weight-loss diet interventions. Circulating miR-34a might in part contribute to the alterations in the primary bile acid subtypes in obese adults.