Hydrophobic Bile Salts Research Articles

Functional Disorders of the Biliary Tract and Cholelithiasis: Analysis of a Possible Relationship

Aim: Diagnostic criteria for functional disorders of the biliary tract are presented in the materials of the Rome IV consensus, as well as expert councils of Russian and foreign specialists. Episodes of functional biliary pain are caused by a violation of bile outflow through the cystic duct and sphincter of Oddi. It has been suggested that there is a “biliary continuum” in which in some patients’ biliary dysfunction is transformed into cholelithiasis. Key points. Lithogenic bile is considered as the pathophysiological basis for the development of biliary dyskinesia and cholelithiasis. Lithogenic bile provokes inflammation of low grades in the mucous membrane of the biliary tract, decreased contractility of the gallbladder and impaired relaxation of the biliary sphincters, impaired physiological response to cholecystokinin. Changes in motility of the biliary tract may be associated with the influence of hydrophobic bile salts and impaired eicosanoid metabolism. Hyperplasia of the epithelium and muscle layer, hypersecretion of mucin and cholesterol precipitation further impair the outflow of bile. Experimental data and some clinical observations indicate the possibility of transformation of biliary dysfunction into cholelithiasis. Dysfunction of the sphincter of Oddi is one of the possible consequences of cholecystectomy and, in fact, acts as a variant of postcholecystectomy syndrome. The basis for the treatment of biliary dysfunctions are antispasmodics of different classes, which can be combined with ursodeoxycholic acid. The biliary tract-selective antispasmodic hymecromone has shown high effectiveness in relieving biliary pain, which also has a moderate choleretic effect and the ability to prevent the crystallization of cholesterol in bile and can be used both for functional diseases and for cholelithiasis. The domestic drug hymecromone “Odecromone” entered the pharmaceutical market. Conclusion. There is no doubt that the relevance of further study of the patterns of development of biliary dysfunctions and GI is obvious. The study of this problem will contribute to the development of effective preventive approaches, including in the field of nutraceuticals.

Adsorption of bile salts onto crystalline ritonavir particles under simulated gastrointestinal conditions

The formation of a biomolecular corona on nanoparticles in blood is a well-known phenomenon influencing in vivo performance. Analogous phenomena in other biological fluids, such as the formation of a gastrointestinal (GI) corona, remain under-investigated. The ingestion of medicines leads to the generation of drug particles in the GI fluids. Consequently, an understanding of the behavior of drug particles in the gut requires determination of the adsorption of bile components onto these drug particles. This work aims to elucidate the factors affecting adsorption of bile salts onto ritonavir (RTV) particles. Crystalline RTV particles were incubated with non-micellar or micellar bile salts and bile salt depletion from solution was measured using HPLC and small angle X-ray scattering (SAXS). HPLC results show that bile salts adsorb onto RTV particles, with greater adsorption observed for more hydrophobic bile salts, following the order sodium glycodeoxycholate (SGDC)>sodium taurodeoxycholate (STDC)>sodium glycochenodeoxycholate SGCDC>sodium glycocholate (SGC)>sodium taurocholate (STC). Increasing the ionic strength of the solution led to increased adsorption of STDC, where buffer containing 300 mM NaCl resulted in greater adsorption than 150 mM NaCl. Additionally, micellar bile salts showed greater affinity for RTV particles than unimeric bile salts. In contrast, the extent of bile salt depletion was unaltered by addition of phospholipid to form mixed micelles. SAXS analysis of mixed micelles after incubation with RTV particles confirms depletion of bile salt from the supernatant, evidenced by reduced intensity of the micellar scattering feature. In conclusion, this study investigated factors influencing bile salt adsorption onto drug particles, highlighting the need to consider adsorption of bile components in forming the GI-corona.

Study on the acute toxicity of sodium taurocholate via zebrafish mortality, behavioral response, and NMR-metabolomics analysis

Sodium taurocholate (NaT) is a hydrophobic bile salt that exhibits varying toxicity and antimicrobial activity. The accumulation of BSs during their entero-hepatic cycle causes cytotoxicity in the liver and intestine and could also alter the intestinal microbiome leading to various diseases. In this research, the acute toxicity of sodium taurocholate in different concentrations (3000 mg/L, 1500 mg/L, 750 mg/L, 375 mg/L, and 0 mg/L) was investigated on four months old zebrafish by immersion in water for 96 h. The results were determined based on the fish mortality, behavioral response, and NMR metabolomics analysis which revealed LC50 of 1760.32 mg/L and 1050.42 mg/L after 72 and 96 h treatment, respectively. However, the non-lethal NaT concentrations of 750 mg/L and 375 mg/L at 96 h exposure significantly (p ≤ 0.05) decreased the total distance traveled and the activity duration, also caused surface respiration on the zebrafish. Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) revealed that the metabolome of the fish treated with 750 mg/L was discriminated from that of the control by PC1. Major significantly downregulated metabolites by NaT-induction include valine, isoleucine, 2-hydroxyvalerate, glycine, glycerol, choline, glucose, pyruvate, anserine, threonine, carnitine and homoserine. On the contrary, taurine, creatine, lactate, acetate and 3-hydroxybutyrate were upregulated suggesting cellular consumption of lipids, glucose and amino acids for adenosine triphosphate (ATP) generation during immune and inflammatory response. whereby these metabolites were released in the process. In conclusion, the research revealed the toxic effect of NaT and its potential to trigger changes in zebrafish metabolism.

High-fat diets enhance and delay ursodeoxycholic acid absorption but elevate circulating hydrophobic bile salts.

Background: Ursodeoxycholic acid (UDCA) is a natural drug essential for the treatment of cholestatic liver diseases. The food effects on the absorption of UDCA and the disposition of circulating bile salts remain unclear despite its widespread global uses. This study aims to investigate the effects of high-fat (HF) diets on the pharmacokinetics of UDCA and disclose how the circulated bile salts were simultaneously perturbed. Methods: After an overnight fast, a cohort of 36 healthy subjects received a single oral dose (500mg) of UDCA capsules, and another cohort of 31 healthy subjects received the same dose after consuming a 900kcal HF meal. Blood samples were collected from 48h pre-dose up to 72h post-dose for pharmacokinetic assessment and bile acid profiling analysis. Results: The HF diets significantly delayed the absorption of UDCA, with the Tmax of UDCA and its major metabolite, glycoursodeoxycholic acid (GUDCA), changing from 3.3h and 8.0h in the fasting study to 4.5h and 10.0h in the fed study, respectively. The HF diets did not alter the Cmax of UDCA and GUDCA but immediately led to a sharp increase in the plasma levels of endogenous bile salts including those hydrophobic ones. The AUC0-72h of UDCA significantly increased from 25.4μg h/mL in the fasting study to 30.8μg h/mL in the fed study, while the AUC0-72h of GUDCA showed no difference in both studies. As a result, the Cmax of total UDCA (the sum of UDCA, GUDCA, and TUDCA) showed a significant elevation, while the AUC0-72h of total UDCA showed a slight increase without significance in the fed study compared to the fasting study. Conclusion: The HF diets delay UDCA absorption due to the extension of gastric empty time. Although UDCA absorption was slightly enhanced by the HF diets, the beneficial effect may be limited in consideration of the simultaneous elevation of circulating hydrophobic bile salts.

Hydrophobic Bile Salts Induce Pro-Fibrogenic Proliferation of Hepatic Stellate Cells through PI3K p110 Alpha Signaling.

Bile salts accumulating during cholestatic liver disease are believed to promote liver fibrosis. We have recently shown that chenodeoxycholate (CDC) induces expansion of hepatic stellate cells (HSCs) in vivo, thereby promoting liver fibrosis. Mechanisms underlying bile salt-induced fibrogenesis remain elusive. We aimed to characterize the effects of different bile salts on HSC biology and investigated underlying signaling pathways. Murine HSCs (mHSCs) were stimulated with hydrophilic and hydrophobic bile salts. Proliferation, cell mass, collagen deposition, and activation of signaling pathways were determined. Activation of the human HSC cell line LX 2 was assessed by quantification of α-smooth muscle actin (αSMA) expression. Phosphatidyl-inositol-3-kinase (PI3K)-dependent signaling was inhibited both pharmacologically and by siRNA. CDC, the most abundant bile salt accumulating in human cholestasis, but no other bile salt tested, induced Protein kinase B (PKB) phosphorylation and promoted HSC proliferation and subsequent collagen deposition. Pharmacological inhibition of the upstream target PI3K-inhibited activation of PKB and pro-fibrogenic proliferation of HSCs. The PI3K p110α-specific inhibitor Alpelisib and siRNA-mediated knockdown of p110α ameliorated pro-fibrogenic activation of mHSC and LX 2 cells, respectively. In summary, pro-fibrogenic signaling in mHSCs is selectively induced by CDC. PI3K p110α may be a potential therapeutic target for the inhibition of bile salt-induced fibrogenesis in cholestasis.

Structural changes in trypsin induced by the bile salts: An effect of amphiphile hydrophobicity

The present study reports the multi-technique results of the interaction of a series of bile salts, sodium cholate (NaC), sodium taurocholate (NaTC), sodium deoxycholate (NaDC), and sodium taurodeoxycholate (NaTDC) with trypsin under the experimental conditions of 25 °C and pH 7.0. The interactions between trypsin and the bile salts were characterized by the surface tension measurements and various spectroscopic techniques like UV–Visible absorption, steady-state fluorescence, and circular dichroism. The results of surface tension measurements reveal a strong interaction of trypsin (50 μM) with the increasing concentration of bile salts, being higher with the bile salt of greater hydrophobicity. The critical aggregation concentration of bile salts in the presence of trypsin (C1) showed that the bile salts interact strongly with the trypsin in the order of NaTDC > NaDC > NaTC > NaC. UV–visible, steady-state fluorescence, and circular dichroism spectroscopic results confirmed significant unfolding of trypsin due to its interaction with the bile salts, the extent of which followed the same sequence as observed in the surface tension results. It could be concluded that the hydrophobic bile salts that show lower C1 values and have less delocalized charge, are more effective in unfolding the trypsin. The study would help understand the hydrophobicity-driven unfolding of proteins aided by biological surfactants like bile salts and help devise efficient proteolytic enzyme-based detergent formulations and understand the role of such amphiphiles as antimicrobial agents.

PGC-1α is downregulated in a mouse model of obstructive cholestasis but not in a model of liver fibrosis.

Several studies have indicated that cholestatic liver damage involves mitochondria dysfunction. However, the precise mechanism by which hydrophobic bile salts cause mitochondrial dysfunction is not clear. In this study, we intended to determine the pathogenesis of cholestatic liver injury associated with peroxisome proliferator-activated receptor-γ co-activator 1α (PGC-1α). A mouse model of cholestatic liver disease was generated by surgical ligation of the bile duct (BDL), and a mouse model of fibrosis was developed through serial administration of thioacetamide. After obtaining liver specimens on scheduled days, we compared the expression of the antioxidant enzymes (superoxide dismutase 2 [SOD2], catalase, and glutathione peroxidase-1[GPx-1]) and PGC-1α in livers from mice with fibrosis and cholestasis using western blotting, immunohistochemistry, and immunofluorescence. We found that cholestatic livers exhibit lower expression of antioxidant enzymes, such as SOD2, catalase, and PGC-1α. In contrast, fibrotic livers exhibit higher expression of antioxidant enzymes and PGC-1α. In addition, cholestatic livers exhibited significantly lower expression of pro-apoptotic markers (Bax) as compared to fibrotic livers. It is well known that overexpression of PGC-1α increases mitochondrial antioxidant enzyme expression, and vice versa. Thus, we concluded that obstructive cholestasis decreases expression of PGC-1α, which may lead to decreased expression of mitochondrial antioxidant enzymes, thereby rendering mice with cholestatic livers vulnerable to ROS-induced cell death.

Retention of primary bile salts by dry beans (Phaseolus vulgaris L.) during in vitro digestion: Role of bean components and effect of food processing

The positive effect of common beans on reducing blood cholesterol levels has been linked to their ability to sequester bile salts (BS) and prevent their recycling. We have examined the preferences of major bean components (soluble/insoluble fiber, starch and proteins) to retain BS, and the role played by the bean matrix. Additionally, the kinetics of BS-release were evaluated in bean flours generated by a combination of hydrothermal or high-hydrostatic pressure (HHP), and mechanical treatments. An in vitro digestion model combined with dialysis was used to evaluate separately the retention of primary individual BS. Soluble fiber retained a significant proportion of BS mainly due to an increased digesta viscosity; however, the protein fraction exhibited the greatest BS retention without affecting viscosity. The thermal properties of proteins and starch were more significantly affected in presence of tauro-chenodeoxycholate, which correlated to the affinity of both fractions to retain more hydrophobic BS during digestion. Glyco-chenodeoxycholate and tauro-cholate were the most and least effectively retained BS by bean flours, respectively. Neither of the processing treatments had an impact on the binding preferences of bean flours to the primary BS; however, the largest BS retention was caused by HHP at 600 MPa. Bean materials preferentially delayed the release of chenodeoxycholate BS, which is probably related to BS micelle formation. These findings demonstrate that a combination of viscosity, molecular and compositional factors is triggering the BS-retention capacity of beans, and indicate the importance of evaluating contribution of individual bean components and as whole system.

Glycochenodeoxycholate Promotes Liver Fibrosis in Mice with Hepatocellular Cholestasis.

Hydrophobic bile salts are considered to promote liver fibrosis in cholestasis. However, evidence for this widely accepted hypothesis remains scarce. In established animal models of cholestasis, e.g., by Mdr2 knockout, cholestasis and fibrosis are both secondary to biliary damage. Therefore, to test the specific contribution of accumulating bile salts to liver fibrosis in cholestatic disease, we applied the unique model of inducible hepatocellular cholestasis in cholate-fed Atp8b1G308V/G308V mice. Glycochenodeoxycholate (GCDCA) was supplemented to humanize the murine bile salt pool, as confirmed by HPLC. Biomarkers of cholestasis and liver fibrosis were quantified. Hepatic stellate cells (HSC) isolated from wild-type mice were stimulated with bile salts. Proliferation, cell accumulation, and collagen deposition of HSC were determined. In cholestatic Atp8b1G308V/G308V mice, increased hepatic expression of αSMA and collagen1a mRNA and excess hepatic collagen deposition indicated development of liver fibrosis only upon GCDCA supplementation. In vitro, numbers of myofibroblasts and deposition of collagen were increased after incubation with hydrophobic but not hydrophilic bile salts, and associated with EGFR and MEK1/2 activation. We concluded that chronic hepatocellular cholestasis alone, independently of biliary damage, induces liver fibrosis in mice in presence of the human bile salt GCDCA. Bile salts may have direct pro-fibrotic effects on HSC, putatively involving EGFR and MEK1/2 signaling.

Blocking Sodium-Taurocholate Cotransporting Polypeptide Stimulates Biliary Cholesterol and Phospholipid Secretion in Mice.

Active secretion of bile salts into the canalicular lumen drives bile formation and promotes biliary cholesterol and phospholipid output. Disrupting hepatic bile salt uptake, by inhibition of sodium‐taurocholate cotransporting polypetide (NTCP; Slc10a1) with Myrcludex B, is expected to limit bile salt flux through the liver and thereby to decrease biliary lipid excretion. Here, we show that Myrcludex B–mediated NTCP inhibition actually causes an increase in biliary cholesterol and phospholipid excretion whereas biliary bile salt output and bile salt composition remains unchanged. Increased lysosomal discharge into bile was excluded as a potential contributor to increased biliary lipid secretion. Induction of cholesterol secretion was not a consequence of increased ATP‐binding cassette subfamily G member 5/8 activity given that NTCP inhibition still promoted cholesterol excretion in Abcg8 −/− mice. Stimulatory effects of NTCP inhibition were maintained in Sr‐b1 −/− mice, eliminating the possibility that the increase in biliary lipids was derived from enhanced uptake of high‐density lipoprotein–derived lipids. NTCP inhibition shifts bile salt uptake, which is generally more periportally restricted, toward pericentral hepatocytes, as was visualized using a fluorescently labeled conjugated bile salt. As a consequence, exposure of the canalicular membrane to bile salts was increased, allowing for more cholesterol and phospholipid molecules to be excreted per bile salt. Conclusion: NTCP inhibition increases biliary lipid secretion, which is independent of alterations in bile salt output, biliary bile salt hydrophobicity, or increased activity of dedicated cholesterol and phospholipid transporters. Instead, NTCP inhibition shifts hepatic bile salt uptake from mainly periportal hepatocytes toward pericentral hepatocytes, thereby increasing exposure of the canalicular membrane to bile salts linking to increased biliary cholesterol secretion. This process provides an additional level of control to biliary cholesterol and phospholipid secretion.

Regulation of Plasma Membrane Localization of the Na⁺-Taurocholate Co-Transporting Polypeptide by Glycochenodeoxycholate and Tauroursodeoxycholate.

Hydrophobic bile salts, such as glycochenodeoxycholate (GCDC) can trigger hepatocyte apoptosis, which is prevented by tauroursodesoxycholate (TUDC), but the effects of GCDC and TUDC on sinusoidal bile salt uptake via the Na⁺-taurocholate transporting polypeptide (Ntcp) are unclear. The effects of GCDC and TUDC on the plasma membrane localization of Ntcp were studied in perfused rat liver by means of immunofluorescence analysis and super-resolution microscopy. The underlying signaling events were investigated by Western blotting and inhibitor studies. GCDC (20 µmol/l) induced within 60 min a retrieval of Ntcp from the basolateral membrane into the cytosol, which was accompanied by an activating phosphorylation of the Src kinases Fyn and Yes. Both, Fyn activation and the GCDC-induced Ntcp retrieval from the plasma membrane were sensitive to the NADPH oxidase inhibitor apocynin, the antioxidant N-acetylcysteine and the Src family kinase inhibitors SU6656 and PP-2, whereas PP-2 did not inhibit GCDC-induced Yes activation. Internalization of Ntcp by GCDC was also prevented by the protein kinase C (PKC) inhibitor Gö6850. TUDC (20 µmol/l) reversed the GCDC-induced retrieval of Ntcp from the plasma membrane and prevented the activation of Fyn and Yes in GCDC-perfused rat livers. Reinsertion of Ntcp into the basolateral membrane in GCDC-perfused livers by TUDC was sensitive to the protein kinase A (PKA) inhibitor H89 and the integrin-inhibitory peptide GRGDSP, whereas the control peptide GRADSP was ineffective. Ex posure of cultured rat hepatocytes to GCDC (50 µmol/l, 15min) increased the fluorescence intensity of the reactive oxygen fluorescent indicator DCF to about 1.6-fold of untreated controls in a TUDC (50 µmol/l)-sensitive way. GCDC caused a TUDC-sensitive canalicular dilatation without evidence for Bsep retrieval from the canalicular membrane. The present study suggests that GCDC triggers the retrieval of Ntcp from the basolateral membrane into the cytosol through an oxidative stress-dependent activation of Fyn. TUDC prevents the GCDC-induced Fyn activation and Ntcp retrieval through integrin-dependent activation of PKA.

Experimental Evidence of Liver Injury by BSEP-Inhibiting Drugs With a Bile Salt Supplementation in Rats.

The bile salt export pump (BSEP, ABCB11) mediates bile acid efflux from hepatocytes into bile. Although the inhibition of BSEP has been implicated as an important mechanism of drug-induced liver injury (DILI), liver injury caused by BSEP-inhibiting drugs is rarely reproduced in experimental animals, probably due to species differences in bile acid composition between humans and rodents. In this study, we tested whether supplementation with chenodeoxycholic acid (CDCA) sodium, a hydrophobic bile salt, could sensitize rats to liver injury caused by a BSEP-inhibiting drug. A potent BSEP inhibitor, ketoconazole (KTZ), which is associated with clinical DILI, was intragastrically administered simultaneously with CDCA at a nontoxic dose once a day for 3 days. Plasma transaminase levels significantly increased in rats receiving CDCA+KTZ, whereas neither treatment with CDCA alone, KTZ alone nor a combination of CDCA and miconazole, a safe analog to KTZ, induced liver injury. In CDCA+KTZ-treated rats, most bile acid species in the liver significantly increased compared with treatment with vehicle or CDCA alone, suggesting that KTZ administration inhibited bile acid excretion. Furthermore, hepatic mRNA expression levels of a bile acid synthesis enzyme, Cyp7a1, and a basolateral bile salt influx transporter, Ntcp, decreased, whereas a canalicular phosphatidylcholine flippase, Mdr2, increased in the CDCA+KTZ group to compensate for hepatic bile acid accumulation. In conclusion, we found that oral CDCA supplementation predisposed rats to KTZ-induced liver injury due to the hepatic accumulation of bile acids. This method may be useful for assessing the potential of BSEP-inhibiting drugs inducing liver injury in vivo.

Polydatin protects against acute cholestatic liver injury in mice via the inhibition of oxidative stress and endoplasmic reticulum stress

Abstract Cholestatic liver injury is a chronic disease caused by the retention of toxic hydrophobic bile salts in the liver, but lack of efficient therapy. Here, we identified that polydatin (PD), a natural precursor of resveratrol (RES), has potent detoxification effects on cholestatic liver injury. PD inhibited hepatocellular apoptosis and attenuated serum alanine aminotransferase (ALT), aspartate transaminase (AST), total bile acid (TBA), alkaline phosphatase (ALP) and total bilirubin (TBIL) levels in the cholestatic mice induced by alpha-naphthylisothiocyanate (ANIT) and bile duct ligation (BDL). Mechanistically, PD reduced malondialdehyde (MDA) levels and increased superoxide dismutase (SOD) activity, suppressed endoplasmic reticulum (ER) stress, CCAAT/enhancer-binding protein homologous protein (CHOP), phosphorylated eukaryotic initiation factor 2 alpha (p-elf2α) and apoptosis in the liver of the mice, suggesting that PD may alleviate cholestatic liver injury via the inhibition of oxidative stress, ER stress and apoptosis. Our data indicate that PD may be a phytoalexin for cholestatic liver diseases.

Creation of Straight-Chain Cationic Polysaccharide-Based Bile Salt Sequestrants Made from Euglenoid β-1,3-Glucan as Potential Antidiabetic Agents.

Straight-chain polysaccharides have a greater potential of selectively adsorbing hydrophobic bile salts than resin-based bile salt sequesters because of ionic and hydrophobic interactions; hence, they may possess antidiabetic activity. The feasibility of using cationic polysaccharides made from euglenoid β-1,3-glucan (referred to as paramylon) as potential antidiabetic agents was examined by using in vitro and animal experiments. Cationic straight-chain polysaccharides were synthesized from euglenoid polysaccharide and glycidyltrimethylammonium chloride. The effects of administration of the synthetic polysaccharide on metabolic syndrome-related indicators were examined in high-fat diet-induced obesity mice. The degree of adsorption of bile salts by the polysaccharides was evaluated using spectroscopic analysis. Administration of the cationic paramylon derivatives significantly reduced body and mesenteric fat weight in high-fat diet-induced obesity mice. A noteworthy effect was that glucagon-like peptide-1 (GLP-1) secretion was approximately three times higher in diet-induced obesity mice receiving cationic paramylon derivatives than in those receiving cellulose as a control. Our results indicate that these cationic paramylon derivatives are potential GLP-1 secretagogues suitable for further study.

Pluronic®-bile salt mixed micelles.

The present study was aimed to examine the interaction of two bile salts viz. sodium cholate (NaC) and sodium deoxycholate (NaDC) with three ethylene polyoxide-polypropylene polyoxide (PEO-PPO-PEO) triblock copolymers with similar PPO but varying PEO micelles with a focus on the effect of pH on mixed micelles. Mixed micelles of moderately hydrophobic Pluronic® P123 were examined in the presence of two bile salts and compared with those from very hydrophobic L121 and very hydrophilic F127. Both the bile salts increase the cloud point (CP) of copolymer solution and decreased apparent micelle hydrodynamic diameter (Dh). SANS study revealed that P123 forms small spherical micelles showing a decrease in size on progressive addition of bile salts. The negatively charged mixed micelles contained fewer P123 molecules but progressively rich in bile salt. NaDC being more hydrophobic displays more pronounced effect than NaC. Interestingly, NaC shows micellar growth in acidic media which has been attributed to the formation of bile acids by protonation of carboxylate ion and subsequent solubilization. In contrast, NaDC showed phase separation at higher concentration. Nuclear Overhauser effect spectroscopy (NOESY) experiments provided information on interaction and location of bile salts in micelles. Results are discussed in terms of hydrophobicity of bile salts and Pluronics® and the site of bile salt in polymer micelles. Proposed molecular interactions are useful to understand more about bile salts which play important role in physiological processes.

No Evidence of Bacterial Biofilm in Recurrent Cholangitis in Primary Sclerosing Cholangitis: A Case Presentation and Introduction of a Hypothesis

Inflammation and fibrosis of the bile ducts are the defining pathological characteristics of Primary Sclerosing Cholangitis (PSC). Among patients listed for liver transplantation, one fifth experience two or more episodes of cholangitis. A previously unexplored explanation for the recurrent nature of cholangitis in PSC is bacterial colonization of the biliary epithelium in the form of biofilm that confers resistance to antibiotics and hosts' phagocytic machinery. The primary aim of the current case was to assess whether bacteria could be seen on the liver explant and whether they organized in the form of biofilm.Figure 1A 60-year-old male with Crohn's disease and PSC presented with recurrent bacterial cholangitis. He did not have dominant bile duct strictures on cholangiogram. Despite ERCP maneuvers, internal-external biliary duct drain placement and long term rotating antibiotics, he continued to experience culturepositive polymicrobial cholangitis and sepsis. During liver transplantation, purulent material was oozing from the liver. Detailed examination of the explant liver pathology using standard light microscopy with gram stain, however, did not reveal any bacterial organism or features of biofilm. We did observe classic features of PSC (images). The patient is well one year after transplant. The pathophysiology of recurrent bacterial cholangitis in a subpopulation of PSC patients is unknown. How enteric organisms gain entry into bile is unclear. The unique association of PSC with inflammatory bowel disease makes portal vein one potential route as bacteria translocate across an inflamed gastrointestinal tract. The presence of dominant strictures of the bile ducts is another logical etiologic suspect in recurrent cholangitis. While several studies have shown that antibiotics improve liver biochemistry in PSC patients, no study has specifically investigated whether patients with or without bacterial cholangitis respond differently to treatment. In our case, despite intraoperative pus, we did not observe bacteria or biofilm on the explant. It may be because the explant specimen was extensively fixed in formalin, known to affect the mucus layer of the mucosa where adherent bacteria reside. Future studies should examine biliary microbiome using fresh unprocessed liver tissue and bile. If biofilm exists in PSC patients with recurrent cholangitis, biofilm-specific treatments such as rifampin, aspirin and hydrophobic bile salts could be further investigated.Figure 2Figure 3

Two Modes of Associations of Curcumin with Pre- and Nanoaggregated Chitosan Oligosaccharide Lactate: Ionic Strength and Hydrophobic Bile Salt Modulate Partition of Drug and Self-Assembly Process

Chitosan oligosaccharide lactate (COL) has been modified to improve water solubility of chitosan, especially for the uses in drug delivery and biomedical applications. The present study reveals that self-assembly of COL in solution forms nanoaggregates of size 10–30 nm with a critical aggregation concentration (cac) of ∼5 μM. Fluorescence quenching of pyrene establishes that one COL chain may form around five independent hydrophobic microdomains during self-assembly in solution that are crucial to drug–polymer contact. Interaction of COL with a representative hydrophobic drug molecule, curcumin, implies two different kinds of binding mechanisms of curcumin with the pre- and nanoaggregated forms of COL, respectively. A strong ground state interaction between curcumin and nanoaggregated COL has been noted with an association constant of 3.91 × 104 L/mol at 298 K. This association has been found to be diffusion controlled, enthalpy driven, and as consequences of hydrophobic effects due to van der Waals inter...

Cholic acid induces a Cftr dependent biliary secretion and liver growth response in mice.

The cause of Cystic fibrosis liver disease (CFLD), is unknown. It is well recognized that hepatic exposure to hydrophobic bile salts is associated with the development of liver disease. For this reason, we hypothesize that, CFTR dependent variations, in the hepatic handling of hydrophobic bile salts, are related to the development CFLD. To test our hypothesis we studied, in Cftr-/- and control mice, bile production, bile composition and liver pathology, in normal feeding condition and during cholate exposure, either acute (intravenous) or chronic (three weeks via the diet). In Cftr-/- and control mice the basal bile production was comparable. Intravenous taurocholate increased bile production to the same extent in Cftr-/- and control mice. However, chronic cholate exposure increased the bile flow significantly less in Cftr-/- mice than in controls, together with significantly higher biliary bile salt concentration in Cftr-/- mice. Prolonged cholate exposure, however, did not induce CFLD like pathology in Cftr-/- mice. Chronic cholate exposure did induce a significant increase in liver mass in controls that was absent in Cftr-/- mice. Chronic cholate administration induces a cystic fibrosis-specific hepatobiliary phenotype, including changes in bile composition. These changes could not be associated with CFLD like pathological changes in CF mouse livers. However, chronic cholate administration induces liver growth in controls that is absent in Cftr-/- mice. Our findings point to an impaired adaptive homeotrophic liver response to prolonged hydrophobic bile salt exposure in CF conditions.

Effect of substituent pattern and molecular weight of cellulose ethers on interactions with different bile salts

Some known mechanisms proposed for the reduction of blood cholesterol by dietary fibre are: binding with bile salts in the duodenum and prevention of lipid absorption, which can be partially related with the bile salt binding. In order to gain new insights into the mechanisms of the binding of dietary fibre to bile salts, the goal of this work is to study the main interactions between cellulose derivatives and two types of bile salts. Commercial cellulose ethers: methyl (MC), hydroxypropyl (HPC) and hydroxypropylmethyl cellulose (HPMC), have been chosen as dietary fibre due to their highly functional properties important in manufactured food products. Two types of bile salts: sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC), have been chosen to understand the effect of the bile salt type. Interactions in the bulk have been investigated by means of differential scanning calorimetry (DSC) and linear mechanical spectroscopy. Results show that both bile salts have inhibitory effects on the thermal structuring of cellulose ethers and this depends on the number and type of substitution in the derivatised celluloses, and is not dependent upon molecular weight. Concerning the bile salt type, the more hydrophobic bile salt (NaTDC) has greater effect on these interactions, suggesting more efficient adsorption onto cellulose ethers. These findings may have implications in the digestion of cellulose-stabilised food matrices, providing a springboard to develop new healthy cellulose-based food products with improved functional properties.

An integrated analysis of differential miRNA and mRNA expressions in human gallstones.

Gallstone disease, including cholesterol precipitation in bile, increased bile salt hydrophobicity and gallbladder inflammation. Here, we investigated miRNA and mRNA involved in the formation of gallstones, and explored the molecular mechanisms in the development of gallstones. Differentially expressed 17 miRNAs and 525 mRNA were identified based on Illumina sequencing from gallbladder mucosa of patients with or without gallstones, and were validated by randomly selected 6 miRNAs and 8 genes using quantitative RT-PCR. 114 miRNA target genes were identified, whose functions and regulating pathways were related to gallstones. The differentially expressed genes were enriched upon lipoprotein binding and some metabolic pathways, and differentially expressed miRNAs enriched upon ABC transportation and cancer related pathways. A molecular regulatory network consisting of 17 differentially expressed miRNAs, inclusive of their target genes, was constructed. miR-210 and its potential target gene ATP11A were found to be differentially expressed in both miRNA and mRNA profiles. ATP11A was a direct target of miR-210, which was predicted to regulate the ABC-transporters pathway. The expression levels of ATP11A in the gallstone showed inverse correlation with miR-210 expression, and up-regulation of miR-210 could reduce ATP11A expression in HGBEC. This is the first report that indicates the existence of differences in miRNA and mRNA expression in patients with or without gallstones. Our data shed light on further investigating the mechanisms of gallstone formation.