Bile Acid Pool Research Articles

P054 Modulation of the Gut Microbiota-Farnesoid X Receptor Axis Improves Deoxycholic Acid-induced Intestinal Inflammation in Mice

Abstract Background Inflammatory bowel disease (IBD) is associated with gut dysbiosis and dysregulation of bile acid metabolism. A high luminal content of deoxycholic acid (DCA) with consumption of a Westernized diet is implicated in the pathogenesis of IBD. The aim of the study is to explore the role of intestinal microbiota and bile acid metabolism in mice with DCA-induced intestinal inflammation. Methods 4-week-old wild-type C57BL mice were fed with AIN-93G (control diet), AIN-93G+0.2% DCA, AIN-93G+0.2% DCA+6 weeks of fexaramine (FXR agonist), or AIN-93G+0.2% DCA+antibiotic cocktail for 24 weeks. Histopathology, Western blotting, and qPCR were performed on the intestinal tissue. Fecal microbiota was analyzed by 16S rDNA sequencing. Fecal bile acid and short-chain fatty acid (SCFA) levels were analyzed by chromatography. Results Gut dysbiosis and enlarged bile acid pool were observed in DCA-treated mice, accompanied by a lower farnesoid X receptor (FXR) activity in the intestine. Administration of fexaramine mitigated DCA-induced intestinal injury, restored intestinal FXR activity, activated fibroblast growth factor 15, and normalized bile acid metabolism. Furthermore, fexaramine administration increased the abundance of SCFA-producing bacteria. Depletion of the commensal microbiota with antibiotics decreased the diversity of the intestinal microbiota, attenuated bile acid synthesis, and reduced intestinal inflammation induced by DCA. Conclusion DCA induced-intestinal inflammation is associated with alterations of gut microbiota and bile acid profiles. Interventions targeting the gut microbiota-FXR signaling pathway may reduce DCA-induced intestinal disease.

Variation of enterohepatic circulation observed with 75SeHCAT images in the first three hours. Scintigraphic patterns and analysis of their association with the diagnosis of bile acid malabsorption

ObjetiveTo evaluate the enterohepatic circulation of 75-Selenium turoselecolic acid (75Se-SeHCAT) during the first 3 h and its correlation with the abdominal retention at the 7th day (AR7), as contribution to the clinical study of biliar acid malabsorption (BAM). Materials and methods38 patients with chronic diarrhea were retrospectively studied. Acquisition protocol included static abdominal images at 1st, 2nd and 3rd hour and the 7th day after oral administration of the radiopharmaceutical. Images of 1–3 h determined 5 patterns of enterohepatic circulation that, due to their location, were characterized as: 1) gallbladder 2−3 h, 2) gallbladder 3 h, 3) gallbladder-abdomen 2−3 h, 4) abdomen, 5) upper left abdomen. The association of these patterns with the AR7 (Fisher, STATA) were investigated. Patients were classified as Non BAM (AR7 > 15%), mild-BAM (AR7 15−10%), moderate-BAM (AR7 10−5%) or severe-BAM (AR7 < 5%). Results19 patients had an AR7 diagnostic of BAM (7 mild-BAM, 5 moderate-BAM, 7 severe-BAM). The pattern “gallbladder at 2−3 h” was statistically associated with Non BAM (p 0,008), while “gallbladder-abdomen at 2−3 h” was correlated with having BAM (p 0,029). ConclusionVariations detected at the abdominal level in images during the first 3 h were associated with changes in intestinal absorption and the incorporation of the radiopharmaceutical into the pool of bile acids, so visual interpretation of the images at 2nd and 3rd hour could be useful in the final assessment of the study.

Bile Acids Activated Receptors in Inflammatory Bowel Disease.

Once known exclusively for their role in nutrients absorption, bile acids have emerged as signaling molecules, generated from cholesterol breakdown, acting on several immune cells by activating a variety of receptors including the G protein-coupled bile acid receptor 1 (GPABR1 or TGR5), the Farnesoid-X-receptor (FXR) and, as recently discovered, the retinoid-related orphan receptors (ROR)γt. GPBAR1, FXR, and RORγt are highly expressed in cells of the innate and adaptive immune system (i.e., dendritic cells (DCs), macrophages, innate lymphoid 3 cells (ILC3s), and T helper 17 (Th17) lymphocytes) and plays an important role in regulating intestinal and liver immunity, highlighting a role for various bile acid species in regulating immune responses to intestinal microbial antigens. While primary bile acids are generated from the cholesterol breakdown secondary bile acids, the GPBAR1 ligands, and oxo-bile acids derivatives, the RORγt ligands, are generated by the intestinal microbiota, highlighting the potential of these bile acids in mediating the chemical communication between the intestinal microbiota and the host. Changes in intestinal microbiota, dysbiosis, alter the composition of the bile acid pool, promoting the activation of the immune system and development of chronic inflammation. In this review, we focus on the molecular mechanisms by which an altered bile acid signaling promotes intestinal inflammation.

Dynamics of the enterohepatic circulation of bile acids in healthy humans.

Regulation of bile acid metabolism is normally discussed as the regulation of bile acid synthesis, which serves to compensate for intestinal loss in order to maintain a constant pool size. After a meal, bile acids start cycling in the enterohepatic circulation. Farnesoid X receptor-dependent ileal and hepatic processes lead to negative feedback inhibition of bile acid synthesis. When the intestinal bile acid flux decreases, the inhibition of synthesis is released. The degree of inhibition of synthesis and the mechanism and degree of activation are still unknown. Moreover, in humans, a biphasic diurnal expression pattern of bile acid synthesis has been documented, indicating maximal synthesis around 3 PM and 9 PM. Quantitative data on the hourly synthesis schedule as compensation for intestinal loss are lacking. In this review, we describe the classical view on bile acid metabolism and present alternative concepts that are based on the overlooked feature that bile acids transit through the enterohepatic circulation very rapidly. A daily profile of the cycling and total bile acid pool sizes and potential controlled and uncontrolled mechanisms for synthesis are predicted. It remains to be elucidated by which mechanism clock genes interact with the Farnesoid X receptor-controlled regulation of bile acid synthesis. This mechanism could become an attractive target to enhance bile acid synthesis at night, when cholesterol synthesis is high, thus lowering serum LDL-cholesterol.

Hepatic Dysregulation of Bile Acid Homeostasis in Hyperandrogenemic Female Mouse Model of Polycystic Ovary Syndrome

Introduction and Purpose: Polycystic Ovary Syndrome (PCOS) is recognized as the most common endocrine disorder in women of reproductive age. Notably, PCOS women with hyperandrogenism have a pronounced increased risk for cardio-metabolic comorbidities compared with healthy individuals. Bile acids are endocrine signaling molecules that modulate hepatic lipid, glucose, and energy metabolism by aiding in absorption of lipids. Alteration of bile acid homeostasis affects overall metabolic homeostasis and contributes to pathogenesis of an array of metabolic diseases, although the molecular mechanisms of this have not been studied in PCOS. Methods: Four-week old C57BL/6N female mice were implanted subcutaneously with dihydrotestosterone (DHT, 8.0 mg) or vehicle silastic tubes (n=8/grp). Weekly body weight, food intake, and body composition was assessed. Fasting serum was obtained and the oral glucose tolerance test (OGTT) was performed in the last week of treatment. Animals were euthanized on treatment day 90 and livers were harvested. Expression levels of mRNA were assessed using RT-qPCR. Results: DHT treated females had significantly higher liver mass (1,387 ± 51 vs 1,197 ± 29 g, p<0.05), increased lean mass (21.25 ± 0.27 vs 19.58 ± 0.23 g, p<0.05) and increased fat mass (4.83 ± 0.47 vs 3.59 ± 0.36 g, p<0.05) compared to the vehicle counterparts. These hyperandrogenemic females additionally showed altered glucose homeostasis, having increased fasting glucose (201.10 ± 11.11 vs 152.80 ± 9.23 mg/dL, p<0.05) and an increased area under the curve (209.2± 11.0 vs 160.8± 3.5 mg.min/dL, p<0.05) following OGTT. Hepatic expression of both classic (Cyp8b1, 1.4 ± 0.1-fold, p<0.05) and alternative (Cyp7b1, 2.0 ± 0.3-fold, p<0.05) bile acid synthesis cytochrome P450 enzyme genes were significantly upregulated in DHT treated animals. Additionally, expression of sulfotransferase Sult2a2 was completely abolished in DHT treated animals compared with vehicle animals, indicating the possibility of androgen regulation of the sulfonation of bile acids marked for elimination. Liver expression of both the bile acid receptor G-protein coupled bile acid receptor 1 and the androgen receptor were both significantly downregulated (Gpbar1: 0.68 ± 0.08-fold, AR: 0.46 ± 0.04-fold, p<0.05) in DHT treated animals. Conclusions: Bile acid synthesis, transport, and elimination are tightly controlled processes in the liver to maintain a constant bile acid pool and limit reabsorption. Together, our results highlight the potential role of androgens in DHT-treated female mice in the dysregulation of bile acid homeostasis and its potential contribution to influence metabolic dysfunction. (Supported by NIH grants NIGMS P20GM-121334 to LLYC and DGR, and NIH NIDDK R21DK-113500 to DGR and the Mississippi Center of Excellence in Perinatal Research.)

Investigating the Role Intestinal-Specific FXR and SHP in Regulating Lipid Metabolism in Mice

Dysregulation of lipid metabolism is a causal factor that can lead to a variety of disorders, such as obesity and metabolic syndrome. Dietary fats are digested in the small intestine by the physiological detergents known as bile acids. They emulsify the fats and break them down into smaller molecules in order for the enterocytes to absorb the nutrients through simple diffusion or through the utilization of specific lipid transporters. Interestingly, the nuclear receptors farnesoid X receptor (FXR) and small heterodimer partner (SHP) not only regulates bile acid synthesis and circulation, but also lipid metabolism. Although many studies have examined the role of FXR in hepatic and intestinal lipid metabolism, studies investigating the role of SHP in the intestine are still lacking. Although FXR and SHP cooperate to regulate many metabolic pathways, FXR or SHP knockout models exhibit different lipid phenotypes. These data indicate there are FXR-dependent and -independent pathways of SHP that controls lipid metabolism. To delineate these two interconnecting yet separate pathways, we will utilize intestine-specific Shp knockout (IShpKO) and intestine-specific Fxr knockout (IFxrKO) mice model and place them on high fat diet to investigate their intestinal intestinal absorption and transportation of lipids. We will also monitor the bile acid pool in the intestine, serum, and liver in these knockouts to evaluate the consequence of intestinal deletion of Fxr as well as Shp on bile acid homeostasis and how this may affect lipid absorption. These experiments will identify how FXR and/or SHP regulates intestinal fat digestion and absorption and if this is secondary to the alterations in bile acid concentration and lipid transporters. In addition, we will also investigate the intestinal Fxr-Shp double knockout (IDKO) mice model to determine their combined contribution in intestinal lipid metabolism. Overall, the results obtained from this research will elucidate if intestinal FXR and SHP cooperate or can independently regulate lipid metabolism and homeostasis.

Defective Humoral Immunity Disrupts Bile Acid Homeostasis Which Promotes Inflammatory Disease of the Small Bowel

Abstract Mucosal antibodies maintain gut homeostasis by promoting spatial segregation between host tissues and luminal microbes. Whether and how mucosal antibody responses influence gut health through modulation of microbiota composition is unclear. One critical metabolic function carried out exclusively by bacteria in the gut is bio-transformation of host bile acids (BAs), and dysregulation of BAs metabolism has been linked to numerous inflammatory and metabolic diseases in humans. Here, we use a CD19−/− mouse model of antibody-deficiency to demonstrate that a relationship exists between dysbiosis, defects in BA homeostasis, and enteropathy of the small intestine (SI). SI enteropathy that develops in CD19−/− mice is associated with alterations to the luminal BA pool in the SI, marked by significant reductions in the abundance of conjugated BAs. Manipulation of BA availability, adoptive transfer of functional B cells, and ablation of bacterial bile salt hydrolase (bsh) activity all influence the severity of SI enteropathy in CD19−/− mice. Collectively, results from our experiments support a model whereby mucosal humoral immune responses limit inflammatory disease of the small bowel by regulating bacterial BA metabolism.

Variación de la circulación enterohepática a través de la imagen con 75SeHCAT en las 3 primeras horas. Patrones gammagráficos y análisis de su asociación con el diagnóstico de malabsorción de ácidos biliares

ObjetiveTo evaluate the enterohepatic circulation of 75-Selenium turoselecolic acid (75Se-SeHCAT) during the first 3 hours and its correlation with the abdominal retention at the 7th day (AR7), as contribution to the clinical study of biliar acid malabsorption (BAM). Materials and methods38 patients with chronic diarrhea were retrospectively studied. Acquisition protocol included static abdominal images at 1st, 2nd and 3rd hour and the 7th day after oral administration of the radiopharmaceutical. Images of 1 to 3 hours determined 5 patterns of enterohepatic circulation that, due to their location, were characterized as: 1) gallbladder 2-3 hours, 2) gallbladder 3 hours, 3) gallbladder-abdomen 2-3 hours, 4) abdomen, 5) upper left abdomen. The association of these patterns with the AR7 (Fisher, STATA) were investigated. Patients were classified as Non BAM (AR7>15%), mild-BAM (AR7: 15-10%), moderate-BAM (AR7: 10-5%) or severe-BAM (AR7<5%). Results19 patients had an AR7 diagnostic of BAM (7 mild-BAM, 5 moderate-BAM, 7 severe-BAM). The pattern “gallbladder at 2-3 hours” was statistically associated with Non BAM (p 0,008), while “gallbladder-abdomen at 2-3 hours” was correlated with having BAM (p 0,029). ConclusionVariations detected at the abdominal level in images during the first 3 hours were associated with changes in intestinal absorption and the incorporation of the radiopharmaceutical into the pool of bile acids, so visual interpretation of the images at 2nd and 3rd hour could be useful in the final assessment of the study.

Manipulating the Microbiome: An Alternative Treatment for Bile Acid Diarrhoea

Bile acid diarrhoea (BAD) is a widespread gastrointestinal disease that is often misdiagnosed as irritable bowel syndrome and is estimated to affect 1% of the United Kingdom (UK) population alone. BAD is associated with excessive bile acid synthesis secondary to a gastrointestinal or idiopathic disorder (also known as primary BAD). Current licensed treatment in the UK has undesirable effects and has been the same since BAD was first discovered in the 1960s. Bacteria are essential in transforming primary bile acids into secondary bile acids. The profile of an individual’s bile acid pool is central in bile acid homeostasis as bile acids regulate their own synthesis. Therefore, microbiome dysbiosis incurred through changes in diet, stress levels and the introduction of antibiotics may contribute to or be the cause of primary BAD. This literature review focuses on primary BAD, providing an overview of bile acid metabolism, the role of the human gut microbiome in BAD and the potential options for therapeutic intervention in primary BAD through manipulation of the microbiome.

Robust and Comprehensive Targeted Metabolomics Method for Quantification of 50 Different Primary, Secondary, and Sulfated Bile Acids in Multiple Biological Species (Human, Monkey, Rabbit, Dog, and Rat) and Matrices (Plasma and Urine) Using Liquid Chromatography High Resolution Mass Spectrometry (LC-HRMS) Analysis.

Bile acids (BAs) are biomolecules synthesized in the liver from cholesterol and are constituents of bile. The in-vivo BA pool includes more than 50 known diverse BAs which are unconjugated, amino acid conjugated, sulfated, and glucuronidated metabolites. Hemostasis of bile acids is known to be highly regulated and an interplay between liver metabolism, gut microbiome function, intestinal absorption, and enterohepatic recirculation. Interruption of BA homeostasis has been attributed to several metabolic diseases and drug induced liver injury (DILI), and their use as potential biomarkers is increasingly becoming important. Speciated quantitative and comprehensive profiling of BAs in various biomatrices from humans and preclinical animal species are important to understand their significance and biological function. Consequently, a versatile one single bioanalytical method for BAs is required to accommodate quantitation in a broad range of biomatrices from human and preclinical animal species. Here we report a versatile, comprehensive, and high throughput liquid chromatography-high resolution mass spectrometry (LC-HRMS) targeted metabolomics method for quantitative analysis of 50 different BAs in multiple matrices including human serum, plasma, and urine and plasma and urine of preclinical animal species (rat, rabbit, dog, and monkey). The method has been sufficiently qualified for accuracy, precision, robustness, and ruggedness and addresses the issue of nonspecific binding of bile acids to plastic for urine samples. Application of this method includes comparison for BA analysis between matched plasma and serum samples, human and animal species differences in BA pools, data analysis, and visualization of complex BA data using BA indices or ratios to understand BA biology, metabolism, and transport.

Functional and Phylogenetic Diversity of BSH and PVA Enzymes.

Bile salt hydrolase (BSH) and penicillin V acylase (PVA) are related enzymes that are classified as choloylglycine hydrolases (CGH). BSH enzymes have attracted significant interest for their ability to modulate the composition of the bile acid pool, alter bile acid signaling events mediated by the host bile acid receptors FXR and TGR5 and influence cholesterol homeostasis in the host, while PVA enzymes have been widely utilised in an industrial capacity in the production of semi-synthetic antibiotics. The similarities between BSH and PVA enzymes suggest common evolution of these enzymes and shared mechanisms for substrate binding and catalysis. Here, we compare BSH and PVA through analysis of the distribution, phylogeny and biochemistry of these microbial enzymes. The development of new annotation approaches based upon functional enzyme analyses and the potential implications of BSH enzymes for host health are discussed.

The Gut-Liver Axis in Cholestatic Liver Diseases.

The gut-liver axis describes the physiological interplay between the gut and the liver and has important implications for the maintenance of health. Disruptions of this equilibrium are an important factor in the evolution and progression of many liver diseases. The composition of the gut microbiome, the gut barrier, bacterial translocation, and bile acid metabolism are the key features of this cycle. Chronic cholestatic liver diseases include primary sclerosing cholangitis, the generic term secondary sclerosing cholangitis implying the disease secondary sclerosing cholangitis in critically ill patients and primary biliary cirrhosis. Pathophysiology of these diseases is not fully understood but seems to be multifactorial. Knowledge about the alterations of the gut-liver axis influencing the pathogenesis and the outcome of these diseases has considerably increased. Therefore, this review aims to describe the function of the healthy gut-liver axis and to sum up the pathological changes in these cholestatic liver diseases. The review compromises the actual level of knowledge about the gut microbiome (including the mycobiome and the virome), the gut barrier and the consequences of increased gut permeability, the effects of bacterial translocation, and the influence of bile acid composition and pool size in chronic cholestatic liver diseases. Furthermore, therapeutic implications and future scientific objectives are outlined.

Aqueous extracts of Aconite promote thermogenesis in rats with hypothermia via regulating gut microbiota and bile acid metabolism

BackgroundIntermittent or prolonged exposure to severe cold stress disturbs energy homeostasis and can lead to hypothermia, heart failure, Alzheimer’s disease, and so on. As the typical “hot” traditional Chinese medicine, Aconite has been widely used to treat cold-associated diseases for thousands of years, but its critical mechanisms for the promotion of thermogenesis are not fully resolved. Gut microbiota and its metabolites play a crucial role in maintaining energy homeostasis. Here, we investigated whether the aqueous extracts of Aconite (AA) can enhance thermogenesis through modulation of the composition and metabolism of gut microbiota in hypothermic rats.MethodsThe therapeutic effects of AA on body temperature, energy intake, and the histopathology of white adipose tissue and brown adipose tissue of hypothermic rats were assessed. Microbiota analysis based on 16 S rRNA and targeted metabolomics for bile acids (BAs) were used to evaluate the composition of gut microbiota and BAs pool. The antibiotic cocktail treatment was adopted to further confirm the relationship between the gut microbiota and the thermogenesis-promoting effects of AA.ResultsOur results showed a sharp drop in rectal temperature and body surface temperature in hypothermic rats. Administration of AA can significantly increase core body temperature, surface body temperature, energy intake, browning of white adipose tissue, and thermogenesis of brown adipose tissue. Importantly, these ameliorative effects of AA were accompanied by the shift of the disturbed composition of gut microbiota toward a healthier profile and the increased levels of BAs. In addition, the depletion of gut microbiota and the reduction of BAs caused by antibiotic cocktails reduced the thermogenesis-promoting effect of AA.ConclusionsOur results demonstrated that AA promoted thermogenesis in rats with hypothermia via regulating gut microbiota and BAs metabolism. Our findings can also provide a novel solution for the treatment of thermogenesis-associated diseases such as rheumatoid arthritis, obesity, and type 2 diabetes.

Hyocholic acid species as novel biomarkers for metabolic disorders

Hyocholic acid (HCA) is a major bile acid (BA) species in the BA pool of pigs, a species known for its exceptional resistance to spontaneous development of diabetic phenotypes. HCA and its derivatives are also present in human blood and urine. We investigate whether human HCA profiles can predict the development of metabolic disorders. We find in the first cohort (n = 1107) that both obesity and diabetes are associated with lower serum concentrations of HCA species. A separate cohort study (n = 91) validates this finding and further reveals that individuals with pre-diabetes are associated with lower levels of HCA species in feces. Serum HCA levels increase in the patients after gastric bypass surgery (n = 38) and can predict the remission of diabetes two years after surgery. The results are replicated in two independent, prospective cohorts (n = 132 and n = 207), where serum HCA species are found to be strong predictors for metabolic disorders in 5 and 10 years, respectively. These findings underscore the association of HCA species with diabetes, and demonstrate the feasibility of using HCA profiles to assess the future risk of developing metabolic abnormalities.

Resveratrol enhances trans-intestinal cholesterol excretion through selective activation of intestinal liver X receptor alpha

Resveratrol (RSV) is a dietary polyphenol with well-documented cardio-protective activity, but its effects on blood cholesterol levels remain to be established. Due to its poor bioavailability, tissue accumulation of RSV is extremely low except for that in the small intestine. In the present study, we aimed to investigate the dose-dependent effects of RSV on blood cholesterol levels and the involvement of small intestine in the cholesterol-lowering impacts of RSV. Mice were administrated with RSV at various doses with high-fat diet (HFD) or high-fat and high-cholesterol diet (HCD) for 12 weeks. The fecal neutral sterol contents were analyzed, and intestinal perfusion test was performed. An enteric barrier model using Caco-2 cells was established. We observed that RSV reduced blood cholesterol levels in a dose-dependent manner in mice fed with HFD or HCD. Further investigation revealed that RSV administration increased the bile acid pool size but did not affect cholesterol consumption or de novo cholesterol synthesis. Interestingly, RSV promoted trans-intestinal cholesterol excretion (TICE) by 2-fold in the intestinal perfusion test. In addition, RSV upregulated the expressions of ATP-binding cassette sub-family G member 5 or 8 (Abcg5/8) and ATP-binding cassette sub-family B member 1a or 1b (Abcb1a/b) by up to 8 times in the duodenum mucosa but not in the liver. RSV also significantly downregulated the expression of intestinal Niemann-Pick C1-Like 1 (Npc1l1). Knock-down of liver X receptor alpha (LXRα) but not Sirt1 by siRNA significantly blocked RSV-induced cholesterol excretion in Caco-2 cells. In conclusion, RSV could decrease circulating cholesterol levels through enhancing TICE and limiting cholesterol absorption via selective activation of intestinal LXRα.

Secondary bile acid ursodeoxycholic acid alters weight, the gut microbiota, and the bile acid pool in conventional mice.

Ursodeoxycholic acid (commercially available as ursodiol) is a naturally occurring bile acid that is used to treat a variety of hepatic and gastrointestinal diseases. Ursodiol can modulate bile acid pools, which have the potential to alter the gut microbiota community structure. In turn, the gut microbial community can modulate bile acid pools, thus highlighting the interconnectedness of the gut microbiota-bile acid-host axis. Despite these interactions, it remains unclear if and how exogenously administered ursodiol shapes the gut microbial community structure and bile acid pool in conventional mice. This study aims to characterize how ursodiol alters the gastrointestinal ecosystem in conventional mice. C57BL/6J wildtype mice were given one of three doses of ursodiol (50, 150, or 450 mg/kg/day) by oral gavage for 21 days. Alterations in the gut microbiota and bile acids were examined including stool, ileal, and cecal content. Bile acids were also measured in serum. Significant weight loss was seen in mice treated with the low and high dose of ursodiol. Alterations in the microbial community structure and bile acid pool were seen in ileal and cecal content compared to pretreatment, and longitudinally in feces following the 21-day ursodiol treatment. In both ileal and cecal content, members of the Lachnospiraceae Family significantly contributed to the changes observed. This study is the first to provide a comprehensive view of how exogenously administered ursodiol shapes the healthy gastrointestinal ecosystem in conventional mice. Further studies to investigate how these changes in turn modify the host physiologic response are important.

Abstract PS6-59: Impact of Cholecystectomy in Breast Cancer Recurrence

Abstract Background: Several published studies demonstrate that bile acid metabolites may influence the growth of breast cancer cells in vitro. Our group has shown reduced plasma concentrations of cholic acid and chenodeoxycholic acid (primary bile acids) and deoxycholic acid and lithocholic acid (secondary bile acids) in breast cancer patients that later on develop tumor recurrence. Cholecystectomy reduces the circulating bile acid pool. In patients with prior cholecystectomy, changes in bile acid metabolites may contribute to breast cancer tumorigenesis and recurrence. This study investigates our institutional rate of cholecystectomy in women diagnosed with breast cancer and its impact on breast cancer recurrence. Methods: A retrospective review of patients with an invasive breast cancer diagnosis between 2014-2015 was conducted. Demographics, preoperative variables, surgical history and clinical outcome data was collected. 5-year disease-free survival (DFS) was compared using a Log-rank (Mantel-Cox) test. Results: The study included 264 patients with mean age of 60.9. Most were Caucasian (83.5%). The majority were diagnosed at Stage II or lower (80.3%) and had hormone receptor positive, HER2 negative breast cancer (72.9%). Approximately 22.7% of patients had prior cholecystectomy surgery. The only statistically significant heterogeneity in demographic data between patients with and without cholecystectomy was body mass index (BMI). Patients with cholecystectomy had a mean BMI of 33.3, versus 29.1 in patients with intact gallbladders. The 5-year DFS in breast cancer patients with cholecystectomy was 91.6%, versus 97.1% in patients with intact gallbladders (p=0.06). Conclusion: Women with breast cancer who had a history of cholecystectomy had increased rates of breast cancer recurrence over a 5-year period compared to women with breast cancer with intact gallbladders. Although this result was not statistically significant, a trend was seen. Future study of a larger patient sample size sample may lead to a statistical significant difference. The statistically significant difference in BMI between the two patient groups is likely a confounding factor, given increased BMI is a known risk factor for developing cholecystitis and breast cancer. This data supports existing in vitro studies that bile acids may influence the growth of breast cancer cells. There may be utility in closer follow-up of women with breast cancer and a history of cholecystectomy given the increased rate of breast cancer recurrence in this population. Citation Format: Isheeta Madeka, Rohin Gawdi, Katherine L Cook, Akiko Chiba. Impact of Cholecystectomy in Breast Cancer Recurrence [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS6-59.

Effect of type of dietary non‐protein energy source (starch vs. fat) on the body bile acid pool size and composition, faecal bile acid loss and bile acid synthesis in rainbow trout (Oncorhynchusmykiss)

Effect of type of dietary non‐protein energy source (starch vs. fat) on the body bile acid pool size and composition, faecal bile acid loss and bile acid synthesis in rainbow trout (<i>Oncorhynchus</i><i>mykiss</i>)

MECHANISMS IN ENDOCRINOLOGY: FXR signalling: a novel target in metabolic diseases.

During the last decades, it has become clear that the gastrointestinal tract plays a pivotal role in the regulation of glucose homeostasis. More than 40 hormones originate from the gastrointestinal tract and several of these impact glucose metabolism and appetite regulation. An astonishing example of the gut's integrative role in glucose metabolism originates from investigations into bile acid biology. From primary animal studies, it has become clear that bile acids should no longer be labelled as simple detergents necessary for lipid digestion and absorption but should also be recognised as metabolic regulators implicated in lipid, glucose and energy metabolism. The nuclear farnesoid X receptor (FXR) is a part of an exquisite bile acid-sensing system that among other things ensures the optimal size of the bile acid pool. In addition, intestinal and hepatic FXR also impact the regulation of several metabolic processes such as glucose and lipid metabolism. Accordingly, natural and synthetic FXR agonists and certain FXR-regulated factors (i.e. fibroblast growth factor 19 (FGF19)) are increasingly being evaluated as treatments for metabolic diseases such as type 2 diabetes and non-alcoholic fatty liver disease (and its inflammatory version, non-alcoholic steatohepatitis). Interestingly, decreased FXR activation also benefits glucose metabolism. This can be obtained by reducing bile acid absorption using bile acid sequestering agents (approved for the treatment of type 2 diabetes) or inhibitors of intestinal bile acid transporters,that is the apical sodium-dependent bile acid transporter (ASBT). This article discusses recent clinical trials that provide insights about the role of FXR-FGF19-targetted therapy for the treatment of metabolic diseases.

Lactobacillus bile salt hydrolase substrate specificity governs bacterial fitness and host colonization

Primary bile acids (BAs) are a collection of host-synthesized metabolites that shape physiology and metabolism. BAs transit the gastrointestinal tract and are subjected to a variety of chemical transformations encoded by indigenous bacteria. The resulting microbiota-derived BA pool is a mediator of host-microbiota interactions. Bacterial bile salt hydrolases (BSHs) cleave the conjugated glycine or taurine from BAs, an essential upstream step for the production of deconjugated and secondary BAs. Probiotic lactobacilli harbor a considerable number and diversity of BSHs; however, their contribution to Lactobacillus fitness and colonization remains poorly understood. Here, we define and compare the functions of multiple BSHs encoded by Lactobacillus acidophilus and Lactobacillus gasseri Our genetic and biochemical characterization of lactobacilli BSHs lend to a model of Lactobacillus adaptation to the gut. These findings deviate from previous notions that BSHs generally promote colonization and detoxify bile. Rather, we show that BSH enzymatic preferences and the intrinsic chemical features of various BAs determine the toxicity of these molecules during Lactobacillus growth. BSHs were able to alter the Lactobacillus transcriptome in a BA-dependent manner. Finally, BSHs were able to dictate differences in bacterial competition in vitro and in vivo, defining their impact on BSH-encoding bacteria within the greater gastrointestinal tract ecosystem. This work emphasizes the importance of considering the enzymatic preferences of BSHs alongside the conjugated/deconjugated BA-bacterial interaction. These results deepen our understanding of the BA-microbiome axis and provide a framework to engineer lactobacilli with improved bile resistance and use probiotics as BA-altering therapeutics.