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Unconjugated and secondary bile acid profiles in response to higher-fat, lower-carbohydrate diet and associated with related gut microbiota: A 6-month randomized controlled-feeding trial.
Wan, Y, Yuan, J, Li, J, Li, H, Zhang, J, Tang, J, Ni, Y, Huang, T, Wang, F, Zhao, F, et al
Clinical nutrition (Edinburgh, Scotland). 2020;(2):395-404
Abstract
BACKGROUND & AIMS Observational studies have shown that diets high in fat and low in dietary fiber, might have an unfavorable impact on bile acid (BA) profiles, which might further affect host cardiometabolic health. In the current study, we aimed to evaluate the effects of dietary fat content on BA profiles and associated gut microbiota, and their correlates with cardiometabolic risk factors. METHODS In a randomized controlled-feeding trial, healthy young adults were assigned to one of the three diets: a lower-fat diet (fat 20%, carbohydrate 66% and protein 14%), a moderate-fat diet (fat 30%, carbohydrate 56% and protein 14%) and a higher-fat diet (fat 40%, carbohydrate 46% and protein 14%) for 6 months. All the foods were provided during the entire intervention period. The BA profiles, associated gut microbiota and markers of cardiometabolic risk factors were determined before and after intervention. RESULTS The higher-fat diet resulted in an elevated concentration of total BAs (p < 0.001), and unconjugated BAs (p = 0.03) compared with lower-fat diet. Secondary BAs, such as deoxycholic acid (DCA), taurodeoxycholic acid (TDCA), 12ketolithocholic acid (12keto-LCA), 3β-DCA and taurolithocholic acid (TLCA) (p < 0.05 after FDR correction) were significantly increased in the higher-fat diet group after the 6-month intervention. Consistently, the abundances of gut bacteria (Bacteroides, Clostridium, Bifidobacterium and Lactobacillus) which affect bile salt hydrolase gene expression were significantly increased after higher-fat consumption. The change of DCA was positively associated with the relative abundance of Bacteroides (r = 0.31, p = 0.08 after FDR correction). In addition, the changes of fecal concentrations of DCA and 12keto-LCA were positively associated with serum total cholesterol (r > 0.3, p = 0.02 and p = 0.008 after FDR correction, respectively). In line with these findings, serum fibroblast growth factor 19 (FGF19) was marginally significantly elevated in the higher-fat group after intervention (p = 0.05). CONCLUSIONS The higher-fat diet resulted in an alteration of BAs, especially unconjugated BAs and secondary BAs, most likely through actions of gut microbiota. These alterations might confer potentially unfavorable impacts on colonic and host cardiometabolic health in healthy young adults. Clinical trial registry number: NCT02355795 listed on NIH website: ClinicalTrials.gov.
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Bile Acids: Key Regulators and Novel Treatment Targets for Type 2 Diabetes.
Wu, Y, Zhou, A, Tang, L, Lei, Y, Tang, B, Zhang, L
Journal of diabetes research. 2020;:6138438
Abstract
Type 2 diabetes mellitus (T2DM), characterized by insulin resistance and unclear pathogenesis, is a serious menace to human health. Bile acids are the end products of cholesterol catabolism and play an important role in maintaining cholesterol homeostasis. Furthermore, increasing studies suggest that bile acids may regulate glucose tolerance, insulin sensitivity, and energy metabolism, suggesting that bile acids may represent a potential therapeutic target for T2DM. This study summarizes the metabolism of bile acids and, more importantly, changes in their concentrations, constitution, and receptors in diabetes. Furthermore, we provide an overview of the mechanisms underlying the role of bile acids in glucose and lipid metabolism, as well as the occurrence and development of T2DM. Bile acid-targeted therapy may represent a valid approach for T2DM treatment.
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Bile Acids in Patients with Uncontrolled Type 2 Diabetes Mellitus - The Effect of Two Days of Oatmeal Treatment.
Delgado, GE, Krämer, BK, Scharnagl, H, Fauler, G, Stojakovic, T, März, W, Kleber, ME, Lammert, A
Experimental and clinical endocrinology & diabetes : official journal, German Society of Endocrinology [and] German Diabetes Association. 2020;(9):624-630
Abstract
BACKGROUND Beta-glucans are effective in binding bile acids (BA) thereby lowering cholesterol concentration. This might contribute to the beneficial effects of the consumption of β-glucan-rich foods like oatmeal on glucose homeostasis. OBJECTIVE We measured BA serum concentrations in patients with uncontrolled type 2 diabetes (T2DM) to investigate the effect of two days of oatmeal treatment on BA concentration as compared to a conventional T2DM-adapted diet. METHODS The OatMeal And Insulin Resistance study was performed as a randomized, open label crossover dietary intervention study with consecutive inclusion of 15 patients in an inpatient clinical setting. Bile acids were measured by high-resolution mass spectrometry. For statistical analysis, the differences in the concentration of serum BA and laboratory parameters between the fifth day and the third day of each inpatient stay were calculated and the effect compared between both phases by using the Wilcoxon test. RESULTS Whereas there was a mean decrease in total BA following oatmeal treatment (-0.82±1.14 µmol/l), there was no decrease following the control treatment. Glycocholic acid was lower after oatmeal treatment but higher following control treatment (-0.09±0.17 vs. 0.05±0.11 µmol/l). The reduction in total BA was directly correlated with a decrease in proinsulin during the oatmeal phase. Decreases in blood lipids or apolipoproteins were mostly greater after oatmeal treatment, but these differences were not statistically significant. CONCLUSION Two days of oatmeal diet led to significant reductions in total BA as compared to a diabetes-adapted control diet. The magnitude of BA reduction was directly correlated with a decrease in proinsulin.
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A Physiology-Based Model of Bile Acid Distribution and Metabolism Under Healthy and Pathologic Conditions in Human Beings.
Voronova, V, Sokolov, V, Al-Khaifi, A, Straniero, S, Kumar, C, Peskov, K, Helmlinger, G, Rudling, M, Angelin, B
Cellular and molecular gastroenterology and hepatology. 2020;(1):149-170
Abstract
BACKGROUND & AIMS Disturbances of the enterohepatic circulation of bile acids (BAs) are seen in a number of clinically important conditions, including metabolic disorders, hepatic impairment, diarrhea, and gallstone disease. To facilitate the exploration of underlying pathogenic mechanisms, we developed a mathematical model built on quantitative physiological observations across different organs. METHODS The model consists of a set of kinetic equations describing the syntheses of cholic, chenodeoxycholic, and deoxycholic acids, as well as time-related changes of their respective free and conjugated forms in the systemic circulation, the hepatoportal region, and the gastrointestinal tract. The core structure of the model was adapted from previous modeling research and updated based on recent mechanistic insights, including farnesoid X receptor-mediated autoregulation of BA synthesis and selective transport mechanisms. The model was calibrated against existing data on BA distribution and feedback regulation. RESULTS According to model-based predictions, changes in intestinal motility, BA absorption, and biotransformation rates affected BA composition and distribution differently, as follows: (1) inhibition of transintestinal BA flux (eg, in patients with BA malabsorption) or acceleration of intestinal motility, followed by farnesoid X receptor down-regulation, was associated with colonic BA accumulation; (2) in contrast, modulation of the colonic absorption process was predicted to not affect the BA pool significantly; and (3) activation of ileal deconjugation (eg, in patents with small intestinal bacterial overgrowth) was associated with an increase in the BA pool, owing to higher ileal permeability of unconjugated BA species. CONCLUSIONS This model will be useful in further studying how BA enterohepatic circulation modulation may be exploited for therapeutic benefits.
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The effect of exenatide on fasting bile acids in newly diagnosed type 2 diabetes mellitus patients, a pilot study.
Li, B, Hu, Y, Wang, G, Liu, L
BMC pharmacology & toxicology. 2020;(1):44
Abstract
BACKGROUND Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) demonstrated good glycemic efficacy in patients with type 2 diabetes mellitus (T2DM) recent years, whereas studies on GLP-1 RAs' biliary effects were limited. Therefore, we aimed to assess the effect of exenatide on bile acids (BAs) and investigate the role of BAs in the glycemic control effect of exenatide. METHODS Thirty-eight newly diagnosed T2DM participants without glucose-lowering drugs intake were recruited. Plasma total bile acids in fasting state (FTBAs) and other parameters were tested at baseline. Then exenatide were applied to the T2DM participants for 12 weeks. FTBAs and glycemic parameters were measured again after exenatide treatment, and correlation analysis between changes of FTBAs and glycemic parameters were conducted to investigate the role of BAs in the glycemic control effect of exenatide. RESULTS The baseline FTBAs level of T2DM patients had no significance (3.84 ± 2.06 vs. 3.87 ± 2.89, P = 0.954) compared with healthy subjects. After 12-week exenatide treatment for the T2DM patients, FTBAs were decreased from 3.84 ± 2.06 μmol/L to 3.06 ± 1.27 μmol/L (P < 0.01). The correlation analysis showed that changes of FTBAs was positively correlated with changes of FPG (r = 0.355, P < 0.05). CONCLUSIONS Our results demonstrated a decreased FTBAs level after exenatide treatment for 12 weeks, without the interference of metformin and other glucose-lowering drugs. The reduction of FTBAs might not exert a positive role in the glycemic control effect of exenatide. TRIAL REGISTRATION Trial registration number: NCT04303819. Registered in March 11, 2020 - Retrospectively registered.
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Effect of a Flaxseed Lignan Intervention on Circulating Bile Acids in a Placebo-Controlled Randomized, Crossover Trial.
Navarro, SL, Levy, L, Curtis, KR, Elkon, I, Kahsai, OJ, Ammar, HS, Randolph, TW, Hong, NN, Carnevale Neto, F, Raftery, D, et al
Nutrients. 2020;(6)
Abstract
Plant lignans and their microbial metabolites, e.g., enterolactone (ENL), may affect bile acid (BA) metabolism through interaction with hepatic receptors. We evaluated the effects of a flaxseed lignan extract (50 mg/day secoisolariciresinol diglucoside) compared to a placebo for 60 days each on plasma BA concentrations in 46 healthy men and women (20-45 years) using samples from a completed randomized, crossover intervention. Twenty BA species were measured in fasting plasma using LC-MS. ENL was measured in 24-h urines by GC-MS. We tested for (a) effects of the intervention on BA concentrations overall and stratified by ENL excretion; and (b) cross-sectional associations between plasma BA and ENL. We also explored the overlap in bacterial metabolism at the genus level and conducted in vitro anaerobic incubations of stool with lignan substrate to identify genes that are enriched in response to lignan metabolism. There were no intervention effects, overall or stratified by ENL at FDR < 0.05. In the cross-sectional analysis, irrespective of treatment, five secondary BAs were associated with ENL excretion (FDR < 0.05). In vitro analyses showed positive associations between ENL production and bacterial gene expression of the bile acid-inducible gene cluster and hydroxysteroid dehydrogenases. These data suggest overlap in community bacterial metabolism of secondary BA and ENL.
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MAIT cell activation in adolescents is impacted by bile acid concentrations and body weight.
Mendler, A, Pierzchalski, A, Bauer, M, Röder, S, Sattler, A, Standl, M, Borte, M, von Bergen, M, Rolle-Kampczyk, U, Herberth, G
Clinical and experimental immunology. 2020;(2):199-213
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Abstract
Bile acids (BAs) are produced by liver hepatocytes and were recently shown to exert functions additional to their well-known role in lipid digestion. As yet it is not known whether the mucosal-associated invariant T (MAIT) cells, which represent 10-15% of the hepatic T cell population, are affected by BAs. The focus of the present investigation was on the association of BA serum concentration with MAIT cell function and inflammatory parameters as well as on the relationship of these parameters to body weight. Blood samples from 41 normal weight and 41 overweight children of the Lifestyle Immune System Allergy (LISA) study were analyzed with respect to MAIT cell surface and activation markers [CD107a, CD137, CD69, interferon (IFN)-γ, tumor necrosis factor (TNF)-α] after Escherichia coli stimulation, mRNA expression of promyelocytic leukemia zinc finger protein (PLZF) and major histocompatibility complex class I-related gene protein (MR1), the inflammatory markers C-reactive protein (CRP), interleukin (IL)-8 and macrophage inflammatory protein (MIP)-1α as well as the concentrations of 13 conjugated and unconjugated BAs. Higher body weight was associated with reduced MAIT cell activation and expression of natural killer cell marker (NKp80) and chemokine receptor (CXCR3). BA concentrations were positively associated with the inflammatory parameters CRP, IL-8 and MIP-1α, but were negatively associated with the number of activated MAIT cells and the MAIT cell transcription factor PLZF. These relationships were exclusively found with conjugated BAs. BA-mediated inhibition of MAIT cell activation was confirmed in vitro. Thus, conjugated BAs have the capacity to modulate the balance between pro- and anti-inflammatory immune responses.
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Total bile acid-to-cholesterol ratio as a novel noninvasive marker for significant liver fibrosis and cirrhosis in patients with non-cholestatic chronic hepatitis B virus infection.
Yan, LT, Wang, LL, Yao, J, Yang, YT, Mao, XR, Yue, W, Mao, YW, Zhou, W, Chen, QF, Chen, Y, et al
Medicine. 2020;(8):e19248
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Although serum bile acids and total cholesterol (TC) are closely related to liver cirrhosis, the potential diagnostic value of total bile acid-to-cholesterol ratio (TBA/TC) for liver fibrosis is unclear. The present study aimed to evaluate the value of TBA/TC in the diagnosis of cirrhosis and the relationship between TBA/TC and significant liver fibrosis in chronic hepatitis B virus (HBV) infected patients without cholestasis.667 patients with alkaline phosphatase (ALP) ≤ 1.5 upper limit of normal (ULN) and gamma-glutamyl transferase (GGT) ≤ 3 ULN were rigorously included in this cross-sectional study. Liver biopsy was performed in 32 patients and METAVIR scoring system was used to evaluate liver fibrosis stage. Liver ultrasound elastography was performed in 138 patients, significant fibrosis was defined as fibrosis ≥ F2. Multiple logistic regression as well as receiver operating characteristic (ROC) curves analyses were performed.Compared to patients with non-cirrhosis, TBA and TBA/TC were significantly higher in cirrhosis while TC was significantly lower (all P < .001). In multivariate analysis, TBA/TC was also independently associated with cirrhosis [odds ratio (OR) = 1.102, 95% confidence interval (CI): 1.085-1.166]. The area under the curve (AUC) of TBA/TC (0.87) was almost equivalent to the aspartate aminotransferase to platelet ratio index (APRI, AUC = 0.84) and fibrosis 4 score (FIB-4, AUC = 0.80), and the optimal cut-off value for TBA/TC to diagnose cirrhosis was 2.70. Among the patients performed liver biopsy, TBA/TC were significantly higher both in significant fibrosis and cirrhosis as well as significantly correlated with fibrosis stage (all P < .001). Furthermore, In patients performed liver ultrasound elastography, TBA/TC was also independently associated with significant fibrosis (OR = 1.040, 95% CI: 1.001-1.078).Assessment of TBA/TC could serve as an additional marker of significant liver fibrosis and cirrhosis in non-cholestatic chronic HBV infection.
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Adult onset of genetic disorders in bile acid transport in the liver.
Miller, GC, Clouston, AD
Human pathology. 2020;:2-7
Abstract
Although severe deficiencies of canalicular transporter enzymes due to biallelic mutations are well known as causes of progressive cholestatic liver disease in children, it is increasingly recognized that milder disease may occur if a single, heterozygous gene mutation is present. This mild disease, generally presenting initially in adulthood, may have a variety of clinical and histological appearances. Bland canalicular cholestasis is the prototypic change, but it is now clear that some gene mutations, particularly in ABCB4 (encoding MDR3), can cause other patterns that include early cholesterol calculus formation, bile duct injury and disappearance, ductular reactions mimicking large duct obstruction, and, in rare cases, progressive fibrosis. Because the features can be subtle and not diagnostic in isolation, it is generally the combination of a biliary pattern of injury with a suggestive clinical and family history that allows the diagnosis to be suspected. Increased awareness and improved access to genetic testing are likely to result in more frequent diagnosis of these disorders.
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Prediagnostic Plasma Bile Acid Levels and Colon Cancer Risk: A Prospective Study.
Kühn, T, Stepien, M, López-Nogueroles, M, Damms-Machado, A, Sookthai, D, Johnson, T, Roca, M, Hüsing, A, Maldonado, SG, Cross, AJ, et al
Journal of the National Cancer Institute. 2020;(5):516-524
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BACKGROUND Bile acids have been proposed to promote colon carcinogenesis. However, there are limited prospective data on circulating bile acid levels and colon cancer risk in humans. METHODS Associations between prediagnostic plasma levels of 17 primary, secondary, and tertiary bile acid metabolites (conjugated and unconjugated) and colon cancer risk were evaluated in a nested case-control study within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Bile acid levels were quantified by tandem mass spectrometry in samples from 569 incident colon cancer cases and 569 matched controls. Multivariable logistic regression analyses were used to estimate odds ratios (ORs) for colon cancer risk across quartiles of bile acid concentrations. RESULTS Positive associations were observed between colon cancer risk and plasma levels of seven conjugated bile acid metabolites: the primary bile acids glycocholic acid (ORquartile 4 vs quartile 1= 2.22, 95% confidence interval [CI] = 1.52 to 3.26), taurocholic acid (OR = 1.78, 95% CI = 1.23 to 2.58), glycochenodeoxycholic acid (OR = 1.68, 95% CI = 1.13 to 2.48), taurochenodeoxycholic acid (OR = 1.62, 95% CI = 1.11 to 2.36), and glycohyocholic acid (OR = 1.65, 95% CI = 1.13 to 2.40), and the secondary bile acids glycodeoxycholic acid (OR = 1.68, 95% CI = 1.12 to 2.54) and taurodeoxycholic acid (OR = 1.54, 95% CI = 1.02 to 2.31). By contrast, unconjugated bile acids and tertiary bile acids were not associated with risk. CONCLUSIONS This prospective study showed that prediagnostic levels of certain conjugated primary and secondary bile acids were positively associated with risk of colon cancer. Our findings support experimental data to suggest that a high bile acid load is colon cancer promotive.