Bile acid coordinates microbiota homeostasis and systemic immunometabolism in cardiometabolic diseases

Cardiometabolic disease (CMD), characterized with metabolic disorder triggered cardiovascular events, is a leading cause of death and disability. Metabolic disorders trigger chronic low-grade inflammation, and actually, a new concept of metaflammation has been proposed to define the state of metabolism connected with immunological adaptations. Amongst the continuously increased list of systemic metabolites in regulation of immune system, bile acids (BAs) represent a distinct class of metabolites implicated in the whole process of CMD development because of its multifaceted roles in shaping systemic immunometabolism. BAs can directly modulate the immune system by either boosting or inhibiting inflammatory responses via diverse mechanisms. Moreover, BAs are key determinants in maintaining the dynamic communication between the host and microbiota. Importantly, BAs via targeting Farnesoid X receptor (FXR) and diverse other nuclear receptors play key roles in regulating metabolic homeostasis of lipids, glucose, and amino acids. Moreover, BAs axis per se is susceptible to inflammatory and metabolic intervention, and thereby BAs axis may constitute a reciprocal regulatory loop in metaflammation. We thus propose that BAs axis represents a core coordinator in integrating systemic immunometabolism implicated in the process of CMD. We provide an updated summary and an intensive discussion about how BAs shape both the innate and adaptive immune system, and how BAs axis function as a core coordinator in integrating metabolic disorder to chronic inflammation in conditions of CMD.

Understanding the physiological functions of the host xenobiotic-sensing nuclear receptors PXR and CAR on the gut microbiome using genetically modified mice

Pharmacological activation of the xenobiotic-sensing nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) is well-known to increase drug metabolism and reduce inflammation. Little is known regarding their physiological functions on the gut microbiome. In this study, we discovered bivalent hormetic functions of PXR/CAR modulating the richness of the gut microbiome using genetically engineered mice. The absence of PXR or CAR increased microbial richness, and absence of both receptors synergistically increased microbial richness. PXR and CAR deficiency increased the pro-inflammatory bacteria Helicobacteraceae and Helicobacter. Deficiency in both PXR and CAR increased the relative abundance of Lactobacillus, which has bile salt hydrolase activity, corresponding to decreased primary taurine-conjugated bile acids (BAs) in feces, which may lead to higher internal burden of taurine and unconjugated BAs, both of which are linked to inflammation, oxidative stress, and cytotoxicity. The basal effect of PXR/CAR on the gut microbiome was distinct from pharmacological and toxicological activation of these receptors. Common PXR/CAR-targeted bacteria were identified, the majority of which were suppressed by these receptors. hPXR-TG mice had a distinct microbial profile as compared to wild-type mice. This study is the first to unveil the basal functions of PXR and CAR on the gut microbiome.

Recent advances in drug development targeting bile acids transporters and related disease / 药学学报

Bile acids (BAs) are a major component of bile salt, which plays a vital role in the metabolism of lipids in humans. Ninety-five percent of bile acids are recycled by the enterohepatic circulation (EHC), and therefore EHC is essential for bile acid homeostasis. There are four transporters that mediate the transmembrane transport of bile acids, each of which plays an important role in the enterohepatic circulation. Gene defects in bile acid transporters can lead to disorders of the enterohepatic circulation, ultimately leading to clinical phenotypes such as metabolic diseases and even death. Bile transporter expression is altered in patients with various metabolic disease states, suggesting that disruption of bile acid transporters may be a pivotal pathological mechanism for the development of metabolism diseases. Thus, many drugs targeting bile acid transporters are being developed. We provide a concise overview of the progress of bile acid transporters research, discuss the relationship between different bile acid transporters and disease development, and summarize the current progress in drug development targeting bile acid transporters.

Research progress on the role of bile salts in ischemic-type biliary lesion after liver transplantation / 器官移植

Ischemic-type biliary lesion (ITBL) refers to biliary tract injury caused by insufficient blood supply of hepatic artery, which is one of the main factors affecting the long-term survival and quality of life of liver transplant recipients. The incidence of ITBL is associated with cold and warm ischemia, acute and chronic rejection, cytomegalovirus infection and the bile effect, etc. The occurrence of ITBL is a complicated process involving with multiple factors and steps. The therapeutic option of ITBL is extremely limited. A large proportion of ITBL patients should undergo repeated liver transplantation. ITBL has become one of the most critical factors preventing further advancement of liver transplantation. Hence, it is of significance to strengthen prevention and explore more effective modalities. Recent studies have found that toxic injury of bile salts plays a central role in ITBL. Active regulation of bile components, regulation of bile acid-related receptor expression and blockage or activation of bile acid-related signaling pathways probably have potentials in the prevention and treatment of ITBL. In this article, the cytotoxicity of bile salts and the mechanism of bicarbonate umbrella in the incidence and progression of ITBL after liver transplantation were reviewed, aiming to provide reference for the diagnosis and treatment of ITBL.

Expression of ASBT and ASGPR mediated receptors for oral liver-targeting preparations in a rat model of hepatic alveolar echinococcosis / 临床肝胆病杂志

ObjectiveTo investigate the feasibility of apical sodium-dependent bile salt transporter (ASBT) and asialoglycoprotein receptor (ASGPR) in the design of oral liver-targeting preparations for the treatment of hepatic alveolar echinococcosis (HAE) by measuring the expression of ASBT and ASGPR. MethodsA total of 18 male Sprague-Dawley rats were selected, among which 10 were used to establish a model of HAE (HAE group) and 8 were used as controls (normal group). Immunofluorescence assay, Western blotting, and quantitative real-time PCR were used to measure the expression distribution, protein expression level, and mRNA expression level of ASBT in the ileal tissue of HAE model rats and normal rats; the same methods were used to measure the expression level of ASGPR in the non-diseased liver tissue and the marginal zone of liver tissue lesion of HAE model rats and the liver tissue of normal rats. The t-test was used for comparison of normally distributed continuous data between two groups; a one-way analysis of variance was used for comparison between three groups, and the least significant difference t-test was used for comparison between two groups. ResultsThe results of immunofluorescence assay, Western blotting, and quantitative real-time PCR showed that compared with the normal group, the HAE group had significantly upregulated expression of ASBT in the ileal tissue (t=5309, 4.110, and 28.060, all P＜0.05) and a significantly higher expression level of ASGPR (the closer to the lesion, the higher the expression) (F=110666, 128.201, and 143.879, all P＜0.001). ConclusionASBT and ASGPR can be used as potential mediated receptors for oral liver-targeting preparations for HAE, which provides a theoretical basis for the design of oral liver-targeting preparations for the treatment of HAE.

CRISPR-Cas9: A method for establishing rat models of drug metabolism and pharmacokinetics

The 2020 Nobel Prize in Chemistry recognized CRISPR-Cas9, a super-selective and precise gene editing tool. CRISPR-Cas9 has an obvious advantage in editing multiple genes in the same cell, and presents great potential in disease treatment and animal model construction. In recent years, CRISPR-Cas9 has been used to establish a series of rat models of drug metabolism and pharmacokinetics (DMPK), such as

Bile salt hydrolase activity and cholesterol assimilation of lactic acid bacteria isolated from flowers

A total of 16 isolates of lactic acid bacteria (LAB) from flowers were screened for the bile salt hydrolase activity on MRS(de Man, Rogosa and Sharpe; Difco) agar supplemented with 0.5% (w/v) taurodeoxycholic acid. The isolates were dividedinto two groups based on their phenotypic characteristics and 16S rRNA gene sequence analysis of the representativeisolates. Group I isolates were cocci as the members of genus Enterococcus. Isolates FM1-1, FM1-2, FM12-1, andFM12-2 were identified as Enterococcus durans (100% similarity), isolate FM2-3 was identified as Enterococcusgallinarum (99.92% similarity), while the isolate FM11-2 was identified as Enterococcus lactis (99.77% similarity).Group II isolates were rods as the members of genus Lactobacillus. They were identified as Lactobacillus plantarumsubsp. plantarum (the representative isolates, FM3-1 and FM16-2, showed 100% similarity). Eleven isolates, includingFM1-1, FM1-2, FM2-3, FM3-1, FM4-2, FM11-2, FM12-1, FM12-2, FM14-1, FM14-2, and FM16-2, exhibited bilesalt hydrolase activity. All LAB isolates showed the cholesterol assimilated ability ranged from 9.57% to 51.69%. Theisolate FM11-2 efficiently assimilated the cholesterol with 51.69%.

Analysis of Solubilization of Fatty Oil from Euphorbiae Semen on Four Euphorbia Factors Based on Thinking of Self-assembled Micelles in vivo / 中国实验方剂学杂志

Objective: The solubilization of 4 compounds(Euphorbia factor L1,L2,L3 and L8),caused by mixed micelles self-assembled from fatty oil of Euphorbiae Semen and bile salt of intestinal juice,was researched in the simulated human intestinal environment. Method: The mixed micelles were prepared with different amounts of fatty oil of Euphorbiae Semen.The transmission electron microscope(TEM) was used to observe the morphology of the micelles.Particle size detector was used to determine the particle size and Zeta potential.HPLC was used to assay the solubility of these 4 compounds.The variation tendency of the total dissolution of these 4 compounds with the change of standing time was observed. Result: Particle size of the mixed micelles was uniform and its morphology was spherical.The absolute values of Zeta potential were less than 20 mV.When the amount of sodium deoxycholate was fixed 4.96 g·L-1,the solubility of these 4 compounds with the concentration of fatty oil at 0.1-4 g·L-1 were significantly greater than that at the dosage of 0 g·L-1.The solubility of these 4 compounds in the micelles formed by fatty oil was 1.3 to 4 times as much as the micelles without fatty oil.The micelles was stable for 36 h. Conclusion: The micelles self-assembled from fatty oil of Euphorbiae Semen and bile salt of intestinal juice,have significant solubilization effect on Euphorbia factor L1,L2,L3 and L8.This research can lay the foundation for clarifying the detoxification mechanism of removing fatty oil and making frostlike powder from the perspective of pharmaceutics.

Benign Recurrent Intrahepatic Cholestasis Type 2 in Siblings with Novel ABCB11 Mutations / 대한소아소화기영양학회지

Benign recurrent intrahepatic cholestasis (BRIC), a rare cause of cholestasis, is characterized by recurrent episodes of cholestasis without permanent liver damage. BRIC type 2 (BRIC2) is an autosomal recessive disorder caused by ABCB11 mutations. A 6-year-old girl had recurrent episodes of jaundice. At two months of age, jaundice and hepatosplenomegaly developed. Liver function tests showed cholestatic hepatitis. A liver biopsy revealed diffuse giant cell transformation, bile duct paucity, intracytoplasmic cholestasis, and periportal fibrosis. An ABCB11 gene study revealed novel compound heterozygous mutations, including c.2075+3A>G in IVS17 and p.R1221K. Liver function test results were normal at 12 months of age. At six years of age, steatorrhea, jaundice, and pruritus developed. Liver function tests improved following administration of phenylbutyrate and rifampicin. Her younger brother developed jaundice at two months of age and his genetic tests revealed the same mutations as his sister. This is the first report of BRIC2 confirmed by ABCB11 mutations in Korean siblings.

Progressive Familial Intrahepatic Cholestasis in Korea: A Clinicopathological Study of Five Patients

BACKGROUND: Progressive familial intrahepatic cholestasis (PFIC) is a heterogeneous group of autosomal recessive liver diseases that present as neonatal cholestasis. Little is known of this disease in Korea. METHODS: The records of five patients histologically diagnosed with PFIC, one with PFIC1 and four with PFIC2, by liver biopsy or transplant were reviewed, and ATP8B1 and ABCB11 mutation status was analyzed by direct DNA sequencing. Clinicopathological characteristics were correlated with genetic mutations. RESULTS: The first symptom in all patients was jaundice. Histologically, lobular cholestasis with bile plugs was the main finding in all patients, whereas diffuse or periportal cholestasis was identified only in patients with PFIC2. Giant cells and ballooning of hepatocytes were observed in three and three patients with PFIC2, respectively, but not in the patient with PFIC1. Immunostaining showed total loss of bile salt export pump in two patients with PFIC2 and focal loss in two. Lobular and portal based fibrosis were more advanced in PFIC2 than in PFIC1. ATP8B1 and ABCB11 mutations were identified in one PFIC1 and two PFIC2 patients, respectively. One PFIC1 and three PFIC2 patients underwent liver transplantation (LT). At age 7 months, one PFIC2 patient was diagnosed with concurrent hepatocellular carcinoma and infantile hemangioma in an explanted liver. The patient with PFIC1 developed steatohepatitis after LT. One patient showed recurrence of PFIC2 after 10 years and underwent LT. CONCLUSIONS: PFIC is not rare in patients with neonatal cholestasis of unknown origin. Proper clinicopathologic correlation and genetic testing can enable early detection and management.

Combined obeticholic acid and apoptosis inhibitor treatment alleviates liver fibrosis

Obeticholic acid (OCA), the first FXR-targeting drug, has been claimed effective in the therapy of liver fibrosis. However, recent clinical trials indicated that OCA might not be effective against liver fibrosis, possibly due to the lower dosage to reduce the incidence of the side-effect of pruritus. Here we propose a combinatory therapeutic strategy of OCA and apoptosis inhibitor for combating against liver fibrosis. CCl-injured mice, d-galactosamine/LPS (GalN/LPS)-treated mice and cycloheximide/TNF (CHX/TNF)-treated HepG2 cells were employed to assess the effects of OCA, or together with IDN-6556, an apoptosis inhibitor. OCA treatment significantly inhibited hepatic stellate cell (HSC) activation/proliferation and prevented fibrosis. Elevated bile acid (BA) levels and hepatocyte apoptosis triggered the activation and proliferation of HSCs. OCA treatment reduced BA levels but could not inhibit hepatocellular apoptosis. An enhanced anti-fibrotic effect was observed when OCA was co-administrated with IDN-6556. Our study demonstrated that OCA inhibits HSCs activation/proliferation partially by regulating BA homeostasis and thereby inhibiting activation of HSCs. The findings in this study suggest that combined use of apoptosis inhibitor and OCA at lower dosage represents a novel therapeutic strategy for liver fibrosis.

Therapeutic effects of emodin on acute choiestatic hepatitis and mechanism in rats / 中华实用儿科临床杂志

Objective To investigate the therapeutic effects of emodin on acute cholestatic hepatitis and mec-hanism thereof. Methods Fifty Sprague - Dawley (SD)rats were randomly divided into 5 groups and were treated with emodin,ursodeoxycholic acid,dexamethasone,or normal saline respectively for 4 days. On the fifth day gastric perfusion of alpha - naphthylisothiocyanate(ANIT)was performed to establish models of choiestatic hepatitis. Four to six hours after the establishment of model the above mentioned agents were given continuously. Forty - eight hours after the model establishment blood samples were collected from abdominal aorta to examine the total bilirubin(TB),direct bilirubin (DB),alanine aminotransferase(ALT),total bile acid(TBA),aspartate aminotransferase(AST),alkaline phosphatase (ALP),gamma glutamine transferase(GGT). Specimen of liver was collected to undergo pathological examination. Real - time PCR was used to detect the mRNA expression of farnesoid X receptor(FXR),small heterodimer partner (SHP ),bile salt export pump (BSEP ),uridine diphosphate glucuronosyltransferase 2 family polypeptide B4 (UGT2B4). Results The serum levels of total bilirubin (TB),direct bilirubin (DB),alanine aminotransferase (ALT),total bile acids (TBA),aspartate aminotransferase (AST),and alkaline phosphatase (ALP)of the model group were respectively (68. 1 ± 26. 1)μmol/ L,(46. 3 ± 20. 1)μmol/ L,(483 ± 228)U/ L,(159. 1 ± 57. 9)μmol/L,(2. 0 ± 0. 5)U/ L,(996 ± 382)U/ L,(324 ± 120)U/ L. The levels of TB,DB,ALT,TBA,AST,ALP of the emodin group were respectively (15. 0 ± 8. 7)μmol/ L,(10. 8 ± 3. 9)μmol/ L,(147 ± 71)U/ L,(60. 1 ± 22. 7)μmol/ L, (295 ± 104)U/ L,(222 ± 59)U/ L,and were all significantly lower than those of the model group (all P < 0. 05). The levels of TB,DB,ALT,TBA,AST,GGT,ALP of the emodin group were all significantly lower than those of the ursode-oxycholic acid group (all P < 0. 05). The levels of TB,DB,ALT,TBA,GGT,AST were all significantly lower than those of the dexamethasone group (all P < 0. 01). The expression levels of FXR,SHP,BSEP,UGT2B4 mRNA in the emodin group (1. 087 ± 0. 285,0. 892 ± 0. 390,0. 902 ± 0. 149,1. 785 ± 0. 403)were all significantly higher than those of the model group (0. 152 ±0. 088,0. 559 ±0. 194,0. 561 ±0. 123,0. 177 ±0. 039,all P <0. 05). Conclusions By decreasing the levels of TB,DB,ALT,TBA,AST,ALP and reducing pathological changes,emodin has a protective effect on cholestatic hepatitis. It has better effects than ursodeoxycholic acid and dexamethasone. These effects may be due to promoting FXR,SHP,BSEP and UGT2B4 expression.

Relationship between phenotype and genotype of ABCB11 deficiency in siblings and literature review / 中华儿科杂志

Objective@#To explore the relationship between genotype and phenotype of ABCB11 deficiency.@*Methods@#Clinical data of two siblings with ABCB11 deficiency were retrospectively analyzed. Related literature from PubMed, CNKI and Wangfang databases was reviewed to date (up to August 2017) with 'ABCB11 gene’ or 'bile salt export pump’, 'cholestasis’ and 'child’ as key words.@*Results@#The patients were siblings. Both of them presented as jaundice, pruritus and hepatosplenomegaly since 3 days after birth. Significant laboratory findings on admission of the older sister included high total bilirubin, 170 µmol/L;conjugated bilirubin, 115.8 µmol/L;alanine aminotransferase, 168 U/L;total bile acid 186.3 µmol/L and normal gamma-glutamyl transpeptidase. While routine laboratory data of the younger brother were as follows: total bilirubin, 148.8 µmol/L;conjugated bilirubin, 96.3 µmol/L;alanine aminotransferase, 232.8 U/L;total bile acid 226 µmol/L, and normal gamma-glutamyl transpeptidase.Both received ursodeoxycholic acid and fat-soluble vitamins. Liver pathology of the younger brother showed giant hepatocytes with ballooning degeneration, focal necrosis and intrahepatic cholestasis. Both the patients harbor the same compound heterozygous mutations in ABCB11 gene, c.145C>T (p.Q49X) and c.1510G>A (p.E504K). The sister is 9 years old now, with normal liver function. Jaundice faded around 3 months after birth, pruritus relieved at age 5, and medications was stopped since then. The brother progressed to liver failure after an operation on perianal abscess when he was 8-month-old, and received living-related liver transplantation when he was 9 month and 20 days old (from his mother). Now he is 1 year and 5 months old, with normal liver function. Both are under our follow-up. Literature review revealed 18 ABCB11 deficiency patients from 7 families who had apparent different prognoses, within each family the siblings had the same ABCB11 gene mutation. Seven cases relieved after ursodeoxycholic acid therapy and/or partial external biliary diversion, 5 received orthotopic liver transplantation, 2 developed hepatocellular carcinoma and 4 cases died in childhood.@*Conclusions@#The clinical manifestations of ABCB11 deficiency may vary greatly in patients carrying the same genotype, even in siblings. Patients should be managed in individualized maner.

Preparation and characterization of docetaxel incorporated in phosphatidylcholine-sodium desoxycholate mixed micelles / 军事医学

Objective To prepare and characterize docetaxel incorporated phosphatidylcholine -sodium desoxycholate mixed micelles (DOX EPC/SDC MMs).Methods Docetaxel mixed micelles (DOX MMs) were prepared using the co-precipitation method .An optimized formulation was obtained by single factor method , which was used to study the effect of several factors on water solubility of DOX in MMs, including EPC/total(EPC+SDC)concentration, total(EPC+SDC) concentration, the pH and ionic strength of the hydrated solution .Then, the obtained DOX MMs were characterized by investigating particle size distribution and morphology , and by conducting dilute experiments to examin micelle stability . Results The EPC/total ( EPC+SDC) concentration ratio was 0.4.The total supplementary material concentration was 2.5%.Pure water was used to disperse the film .The drug loaded MMs had an average size of 18.56 nm and average zeta potential of -24.3 mV.A roundlike shape was observed under a transmission electron microscope ( TEM).Conclusion DOX EPC/SDC MMs, prepared by a simple and convenient method , can enhance water solubility , is physically compatible with injection solutions and is expected to become a new drug delivery system .

Selection of superior bifidobacteria in the presence of rotavirus

The main purpose of this study was to investigate bifidobacteria flora in fecal samples from children with rotavirus infection and determine the significance of their selected probiotic properties for improvement of health status. Enzyme-linked immunosorbent assay was used to identify rotavirus antigen in fecal samples from 94 patients with gastroenteritis and from 30 without gastroenteritis. Bifidobacteria were identified by selective media, gram reaction, colony morphology, fructose-6-phosphate phosphoketolase enzyme activity and classical identification tests. Exopolysaccharide (EPS) production was identified by phenol-sulphuric acid method. The modified method was then used to identify the quantity of taurocholic and glycocholic acid deconjugation and cholesterol elimination of the strains. Thirty-five of the 94 fecal samples were found positive for rotavirus antigen (37.23%). Bifidobacteria were identified in 59 of the samples. The EPS production ranges were 29.56-102.21 mg/L. The cholesterol elimination rates ranged between 8.36-39.22%. Furthermore, a positive and strong correlation was determined between EPS production and the presence of cholesterol (r=0.984, P<0.001). The deconjugation rates for the sodium glycocholate group was higher than the sodium taurocholate group. Rotavirus (+) bifidobacteria strains had higher EPS production, deconjugation rate and cholesterol elimination compared to bifidobacteria strains isolated from children in the rotavirus (-) sample and without gastroenteritis. Significant differences were observed among groups in all parameters (P<0.05). Given the increased number of rotavirus cases in Turkey and worldwide, it is very important to add superior bifidobacteria in the diets of infected children to improve the intestinal and vital functions.

Nuevas terapias para la colestasis / New therapies in cholestasis

The introduction of ursodeoxycholic acid (UDCA) in the treatment of patients with cholestasis enabled remarkable progress and improvements in hepatic inflammatory activity, progression to cirrhosis and quality of life. However, the benefits of UDCA are particularly evident in patients with primary biliary cirrhosis and also 30 percent of patients have sub optimal response. For this reason, in order to improve the number of people with complete responses to therapy, new pharmacological alternatives have been investigated to add to UDCA treatment. This review aims to show potential new therapies against cholestasis that have been investigated by systematizing them depending on the receptor or target on which they act. Finally, a special reference will be made in relation to the treatment of pruritus associated with cholestasis.

La introducción del ácido ursodeoxicólico (AUDC) en el tratamiento de los pacientes con colestasia permitió notables avances con mejoras en la actividad inflamatoria hepática, progresión hacia la cirrosis y calidad de vida. Sin embargo, los beneficios de AUDC se aprecian especialmente en pacientes con cirrosis biliar primaria y además, 30 por ciento de los pacientes tiene una respuesta sub óptima. Por esta razón, con la finalidad de mejorar el número de personas con respuestas completas a la terapia, se han investigado nuevas alternativas farmacológicas para adicionar al tratamiento con AUDC. La presente revisión pretende mostrar las nuevas posibles terapias contra la colestasia estudiadas sistematizándolas según el tipo de receptor o diana sobre el que actúan. Finalmente se hará referencia especial en relación al tratamiento del prurito asociado a la colestasia.

Bile salt incorporated polypyrrole thin film for ethanol sensing.

Polypyrrole (PPy)-bile salt composite was used for sensing ethanol vapor. PPy was synthesized by interface polymerization for subsequent fabrication of thin film of its composite with bile salt, by in-situ co-dispersion method and then exposed to ethanol vapour. Sensing was visualized through changes in morphological, structural and optical characterizations. The ethanol exposed film showed larger agglomeration as revealed in its surface morphology on scanning electron microscope (SEM) and greater crystallinity as seen through X-Ray diffraction (XRD). Fourier transform infra red (FTIR) and nuclear magnetic resonance spectroscopy (NMR) of the ethanol incorporated film also gave signature of the presence of bile salt and alcohol. Alcohol incorporation pattern resulted in increase in electrical conductance from 7.08539 × 10-5 mA/V to 8.0356 × 10-5 mA/V, as determined from current voltage characterizations. Average molecular weight (Mn) obtained from gel permeation chromatography changed from 6160 to 10300 on ethanol intake. Photoluminescence (PL) intensity was quenched and the PL peak shifted from 430 to 409 on ethanol exposure. Changes in morphological, structural, optical and electrical properties of the composite on ethanol exposure showed its prospective application for sensing ethanol.

The human gut sterolbiome: bile acid-microbiome endocrine aspects and therapeutics

The human body is now viewed as a complex ecosystem that on a cellular and gene level is mainly prokaryotic. The mammalian liver synthesizes and secretes hydrophilic primary bile acids, some of which enter the colon during the enterohepatic circulation, and are converted into numerous hydrophobic metabolites which are capable of entering the portal circulation, returned to the liver, and in humans, accumulating in the biliary pool. Bile acids are hormones that regulate their own synthesis, transport, in addition to glucose and lipid homeostasis, and energy balance. The gut microbial community through their capacity to produce bile acid metabolites distinct from the liver can be thought of as an "endocrine organ" with potential to alter host physiology, perhaps to their own favor. We propose the term "sterolbiome" to describe the genetic potential of the gut microbiome to produce endocrine molecules from endogenous and exogenous steroids in the mammalian gut. The affinity of secondary bile acid metabolites to host nuclear receptors is described, the potential of secondary bile acids to promote tumors, and the potential of bile acids to serve as therapeutic agents are discussed.

Metabolic effects of intestinal absorption and enterohepatic cycling of bile acids

The classical functions of bile acids include acting as detergents to facilitate the digestion and absorption of nutrients in the gut. In addition, bile acids also act as signaling molecules to regulate glucose homeostasis, lipid metabolism and energy expenditure. The signaling potential of bile acids in compartments such as the systemic circulation is regulated in part by an efficient enterohepatic circulation that functions to conserve and channel the pool of bile acids within the intestinal and hepatobiliary compartments. Changes in hepatobiliary and intestinal bile acid transport can alter the composition, size, and distribution of the bile acid pool. These alterations in turn can have significant effects on bile acid signaling and their downstream metabolic targets. This review discusses recent advances in our understanding of the inter-relationship between the enterohepatic cycling of bile acids and the metabolic consequences of signaling via bile acid-activated receptors, such as farnesoid X nuclear receptor (FXR) and the G-protein-coupled bile acid receptor (TGR5).

Bile acids and sphingosine-1-phosphate receptor 2 in hepatic lipid metabolism

The liver is the central organ involved in lipid metabolism. Dyslipidemia and its related disorders, including non-alcoholic fatty liver disease (NAFLD), obesity and other metabolic diseases, are of increasing public health concern due to their increasing prevalence in the population. Besides their well-characterized functions in cholesterol homoeostasis and nutrient absorption, bile acids are also important metabolic regulators and function as signaling hormones by activating specific nuclear receptors, G-protein coupled receptors, and multiple signaling pathways. Recent studies identified a new signaling pathway by which conjugated bile acids (CBA) activate the extracellular regulated protein kinases (ERK1/2) and protein kinase B (AKT) signaling pathway via sphingosine-1-phosphate receptor 2 (S1PR2). CBA-induced activation of S1PR2 is a key regulator of sphingosine kinase 2 (SphK2) and hepatic gene expression. This review focuses on recent findings related to the role of bile acids/S1PR2-mediated signaling pathways in regulating hepatic lipid metabolism.