ARTICLE | doi:10.20944/preprints202308.0779.v1
Subject: Biology And Life Sciences, Endocrinology And Metabolism Keywords: bile acids; colesevelam; enterohepatic circulation; liver; humanized mouse model
Online: 10 August 2023 (04:16:37 CEST)
Bile acids (BAs) and their signalling pathways have been identified as therapeutic targets for liver and metabolic diseases. We generated Cyp2c70-/- (KO) mice that are not able to convert chenodeoxycholic acid into rodent-specific muricholic acids (MCAs) and, hence, possess a more hydrophobic, human-like BA pool. Recently, we have shown that KO mice display cholangiopathic features with development of liver fibrosis. The aim of this study was to determine whether BA sequestration modulates liver pathology in Western type-diet (WTD)-fed KO mice. The BA sequestrant colesevelam was mixed into the WTD (2% w/w) of male Cyp2c70+/+ (WT) and KO mice and the effects were evaluated after 3 weeks of treatment. Colesevelam increased fecal BA excretion in WT and KO mice and reduced the hydrophobicity of biliary BAs in KO mice. Colesevelam ameliorated diet-induced hepatic steatosis in WT mice, whereas KO mice were resistant to diet-induced steatosis and BA sequestration had no additional effects on liver fat content. Total cholesterol concentrations in livers of colesevelam-treated WT and KO mice were significantly lower than those of untreated controls. Of particular note, colesevelam treatment normalized plasma levels of liver damage markers in KO mice and markedly decreased hepatic mRNA levels of fibrogenesis-related genes in KO mice. Lastly, colesevelam did not affect glucose excursions and insulin sensitivity in WT or KO mice. Our data show that BA sequestration ameliorates liver pathology in Cyp2c70-/- mice with a human-like bile acid composition without affecting insulin sensitivity.
ARTICLE | doi:10.20944/preprints202302.0351.v1
Subject: Medicine And Pharmacology, Dermatology Keywords: liver fibrosis; liver cirrhosis; bile duct ligation; animal model
Online: 21 February 2023 (04:21:07 CET)
Liver fibrosis is based on complex interactions between extracellular matrix-producing hepatic stellate cells and is defined as excessive matrix deposition and an abundance of infiltrating cells in the liver. Studying these processes requires in vitro and in vivo experimental work on animals. In fibrosis research, experimental work in rodents is currently the gold standard for confirming a proposed disease-associated mechanism. Bile duct ligation (BDL) induces obstructive jaundice resulting in cholestasis. BDL is useful for preclinical research studies of liver injury due to extrahepatic cholestasis such as apoptosis and fibrosis. Here we provide a stepwise surgical approach to resect the common bile duct and monitor in situ hepatic metabolism by microdialysis.
ARTICLE | doi:10.20944/preprints202102.0335.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: IQGAP1; MST2; LATS1, YAP1, Hippo, Bile acid, hepatocellular carcinoma.
Online: 16 February 2021 (14:08:12 CET)
The Hippo pathway regulates a complex signalling network which mediates several biological functions including cell proliferation, organ size and apoptosis. Several scaffold proteins regulate the crosstalk of the members of the pathway with other signalling pathways and play an important role in the diverse output controlled by this pathway. In this study we have identified the scaffold protein IQGAP1 as a novel interactor of the core kinases of the Hippo pathway, MST2 and LATS1. Our results indicate that IQGAP1 scaffolds MST2 and LATS1, supresses their kinase activity, and YAP1-dependent transcription. Additionally, we show that IQGAP1 is a negative regulator of the non-canonical pro-apoptotic pathway and may enable the crosstalk between this pathway and the ERK and AKT signalling modules. Our data also show that bile acids regulate the IQGAP1-MST2-LATS1 signalling module in hepatocellular carcinoma cells which could be necessary for the inhibition of MST2-dependent apoptosis and hepatocyte transformation.
ARTICLE | doi:10.20944/preprints202208.0202.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: blueberries; bile acids; dietary supplements; polyphenols; LC-MS/MS profiling
Online: 10 August 2022 (11:57:59 CEST)
Cholesterol-derived bile acids (BAs) affect numerous physiological functions such as glucose homeostasis, lipid metabolism and absorption, intestinal inflammation and immunity, as well as intestinal microbiota diversity. Diet influences the composition of the BA pool. The present study analyzes the impact of a dietary supplementation with a freeze-dried blueberry powder (BBP) on the fecal BA pool composition. The diet of 11 men and 13 women at risk for metabolic syndrome was supplemented with 50g/day of BBP for 8 weeks, and feces were harvested before (pre) and after (post) BBP consumption. BAs were profiled using liquid chromatography coupled to tandem mass spectrometry. No significant changes in total BAs were detected when comparing pre- vs post-BBP consumption samples. However, post-BBP consumption samples exhibited significant accumulations of glycine-conjugated BAs (p=0.04), glycochenodeoxycholic (p=0.01) and glycoursodeoxycholic (p=0.01) acids, as well as a significant reduction (p=0.03) of the secondary BA levels, when compared to pre-BBP feces (p=0.03). In conclusion, the fecal bileacidome is significantly altered after the consumption of BBP for 8 weeks. While additional studies are needed to fully understand the underlying mechanisms and physiological implications of these changes, our data suggest that the consumption of blueberries can modulate toxic BAs elimination.
REVIEW | doi:10.20944/preprints202304.0494.v1
Subject: Medicine And Pharmacology, Gastroenterology And Hepatology Keywords: Cholestasis; Bile acid; Ursodeoxycholic acid; Fibrosis; FXR agonist; PXR agonist; Fibreates
Online: 18 April 2023 (05:31:16 CEST)
Cholestasis is a condition defined as an abnormal decrease of bile flow due to progressive pathological states or cholestatic liver diseases that affect the biliary tree at intrahepatic and extrahepatic level. It induces complications such as cirrhosis, liver failure, malignancies, pruritus, fatigue, bone disease and nutritional deficiencies that merit close follow-up and specific interventions to improve quality of life. Furthermore, cholestasis can progress to end-stage liver disease and represents an entity with high morbidity and mortality; and economic burden, Therefore, it is important that clinicians understand the treatment options for cholestatic liver diseases. This review addresses the pathophysiology of cholangiopathies, a general view of current treatments and their molecular targets, and a specific review of those groups of drugs. The objective is to provide clinicians with an overview of the current treatment of cholangiopathies based on evidence on its efficacy and safety.
ARTICLE | doi:10.20944/preprints202201.0328.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: cytochrome oxidase; thyroid hormones; steroid hormones; Bile Acids Binding Site; regulation
Online: 21 January 2022 (13:36:04 CET)
Thyroid hormones regulate tissue metabolism establishing an energy balance in the cell, in particular by affecting oxidative phosphorylation. Their long-term impact is mainly associated with changes in gene expression, while the short-term effects may differ in mechanism. Our work is devoted to short-term effects of hormones T2, T3, and T4 on mitochondrial cytochrome c oxidase (CcO) mediated by a direct contact with the enzyme. The data obtained indicate the existence of two separate sites of CcO interaction with thyroid hormones differing in location, affinity and specificity to hormone binding. It is shown that T3 and T4 but not T2 inhibit oxidase activity of CcO in solution and on membrane preparations with Кi≈100–200 M. In solution, T3 and T4 compete in a 1:1 ratio with the detergent dodecyl-maltoside for binding to the enzyme. Peroxidase and catalase partial activities of CcO are not sensitive to hormones while electron transfer from heme a to the oxidized binuclear center is affected. We believe that T3 and T4 are ligands of the Bile Acid Binding Site found in the 3D structure of CсO by Ferguson-Miller’s group, and hormone induced inhibition is associated with dysfunction of the K- proton channel. Similar conclusion we made recently with regard to steroid-like compounds. It is found that T2, T3, and T4 inhibit superoxide generation by oxidized CcO in the presence of excess Н2О2. Inhibition is characterized by Ki values of 0.3 – 5 M and apparently affects the formation of О2• at the protein surface. The second binding site for thyroid hormones presumably coincides with the point of tight T2 binding on the Va subunit described in the literature.
ARTICLE | doi:10.20944/preprints202305.1372.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: weaned pig; gut microbiota; red beetroot; short chain fatty acids; bile acids
Online: 19 May 2023 (04:11:50 CEST)
Red beetroot, is a well-recognized and established source of bioactives (e.g., betalains and polyphenols) with anti-inflammatory and antimicrobial properties. It is proposed as a potential alternative to zinc oxide, with a focus on gut microbiota modulation and metabolite production. In this study, weaned pigs aged 28-days were fed either a control diet, diet supplemented with zinc oxide (3,000 mg/kg), or 2% and 4% pulverized whole red beetroot (CON, ZNO, RB2 and RB4; respectively) for 14 days. After the pigs were euthanized, blood and digesta samples were collected for microbial composition and metabolite analyses. Results showed, red beetroot supplemented diet at 2% improved the gut microbial richness relative to other diets, but marginally influenced the caecal microbial diversity compared to zinc oxide supplemented diet. Further increase in red beetroot levels (4% -RB4) lead to loss of caecal diversity, decreased short chain fatty acids and secondary bile acid concentrations. An increased Proteobacteria abundance, presumably due to increased lactate/lactic acid producing bacteria was also observed. Summarily, red beetroot contains several components conceived to improve the gut microbiota and metabolite output of weaned pigs. Future studies investigating individual components in red beetroot will better elucidate their contributions to gut microbiota modulation and pig health.
REVIEW | doi:10.20944/preprints202211.0062.v1
Subject: Chemistry And Materials Science, Medicinal Chemistry Keywords: membrane transporter; SLC; solute carrier; drug design; pharmacokinetics; prodrug; nanoparticle; bile acids
Online: 3 November 2022 (01:09:54 CET)
Transmembrane transport of small organic and inorganic molecules is one of the cornerstones of cellular metabolism. Among transmembrane transporters, solute carrier (SLC) proteins form the largest, albeit very diverse, superfamily with over 400 members. It has been early on recognized that xenobiotics can directly interact with SLCs and that this interaction can fundamentally determine their efficacy, including bioavailability and intertissue distribution. Apart from the well-established prodrug strategy, the chemical ligation of transporter substrates to nanoparticles of various chemical composition has recently been used as a means to enhance their targeting or absorption. In this review, we summarize efforts in drug design exploiting interactions with specific SLC transporters to optimize their therapeutic effects. Furthermore, we describe current and future challenges as well as new directions for the advanced development of therapeutics that target SLC transporters.
ARTICLE | doi:10.20944/preprints202006.0204.v1
Subject: Medicine And Pharmacology, Gastroenterology And Hepatology Keywords: Presepsin; Sepsis; Sequential Organ Failure Assessment (SOFA) score; alkaline phosphatase (ALP); Bile
Online: 16 June 2020 (09:43:45 CEST)
Presepsin is a diagnostic and prognostic biomarker of sepsis; however, elevated presepsin levels have also been documented without sepsis. This study aims to retrospectively analyze the laboratory parameters and Sequential Organ Failure Assessment (SOFA) score affecting presepsin levels in 567 patients. Some patients with elevated presepsin levels exhibited renal dysfunction or elevation of biliary enzymes despite a low SOFA score. The univariate regression analysis revealed a close correlation between presepsin levels and SOFA score, serum creatinine (CRE), blood urea nitrogen, and biliary enzymes. In addition, a multivariate regression analysis revealed that SOFA score, alkaline phosphatase (ALP), and CRE independently affected presepsin levels significantly. The analysis of covariance (ANCOVA) revealed that presepsin levels were significantly higher in patients with hepatobiliary disease. Besides, we found that patients who presented with the dilatation of intra- or extrahepatic bile ducts and the elevation of ALP or total bilirubin exhibited remarkable high presepsin levels in the bile. Furthermore, the presepsin production in the liver’s Kupffer cells was established by immunostaining in patients who received surgical liver resection. Overall, this study elucidates that biliary enzymes’ elevation affects presepsin levels, presepsin exists in high concentrations in the bile, and is positive in Kupffer cells.
CASE REPORT | doi:10.20944/preprints202201.0298.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: Checkpoint inhibitors; Immune related adverse events; Cholestasis; Severe ductopenia; Vanishing bile duct syndrome
Online: 20 January 2022 (11:07:21 CET)
Tyrosine kinase inhibitors (TKI) and immune checkpoint inhibitors (ICI) significantly improve the outcomes of patients with advanced clear cell renal cell carcinoma (ccRCC), but high-grade toxicities can occur, particularly during combination therapy. Herein, we report a patient with advanced metastatic ccRCC, who developed grade 4 cholestasis during combined therapy with nivolumab and cabozantinib. After the exclusion of common disorders associated with choles-tasis and a failure of corticosteroids (CS), a liver biopsy was performed that demonstrated severe ductopenia. Consequently, a diagnosis of vanishing bile duct syndrome related to TKI and ICI administration was made, resulting in CS discontinuation and ursodeoxycholic acid administra-tion. After a 7-months follow-up, liver tests had returned to normal values. Immunological studies revealed that our patient had developed robust T-cells and macrophages infiltrates in his lung metastasis, as well as in skin and liver tissues at the onset of toxicities. At the same time, peripheral blood immunophenotyping revealed significant changes in T-cell subsets suggesting their potential role in the pathophysiology of the disease.
ARTICLE | doi:10.20944/preprints202008.0180.v1
Subject: Medicine And Pharmacology, Pediatrics, Perinatology And Child Health Keywords: biliary atresia; Kasai portoenterostomy; cholangitis; portal hypertension; bile ducts dilatations; native liver survival
Online: 7 August 2020 (09:27:14 CEST)
The prospective study enrolled 144 patients after surgical treatment of biliary atresia in early infancy. We analyze the immediate effectiveness of the surgery and the age-related structure of complications in the up to 16-year follow-up. The immediate 2-year survival rate after the surgery constituted 49.5%. At the time of this writing, 17 of the patients have celebrated their 10th birthdays with good quality of life and no indications for LT. The obtained results underscore the critical importance of surgical correction of BA by Kasai surgery during the first 60 days of life and subsequent dynamic follow-up of the patients for the purpose of the early detection and timely correction of possible complications.
REVIEW | doi:10.20944/preprints202308.1574.v1
Subject: Medicine And Pharmacology, Gastroenterology And Hepatology Keywords: acute pancreatitis; idiopathic acute pancreatitis; echoendoscopy; endosonography; endoscopic ultrasound; microlithiasis; biliary pancreatitis; bile duct stones
Online: 22 August 2023 (11:59:36 CEST)
Idiopathic acute pancreatitis (IAP) presents a diagnostic challenge and refers to cases where the cause of acute pancreatitis remains uncertain despite a comprehensive diagnostic evalua-tion. Endoscopic ultrasound (EUS) has emerged as a valuable tool in the diagnostic workup of IAP. This review explores the pivotal role of EUS in detecting the actual cause of IAP, as-sessing its accuracy, timing, safety, and future technological improvement. Following PRISMA guidelines, 60 pertinent studies were selected and analysed. EUS emerges as a cru-cial diagnostic tool, particularly when conventional imaging fails. It can offer intricate visu-alization of the pancreas, biliary system, and adjacent structures. High accuracy of EUS is evident in detecting the actual causes of IAP such as microlithiasis, small bile duct stones, pancreas divisum, and small pancreatic tumors. Optimal timing for EUS is post-resolution of the acute phase of the disease. EUS, when conducted by experienced endoscopists, it boasts minimal safety concerns, and is crucial to prevent complications. EUS-guided interventions, including fine-needle aspiration, collection drainage, and biopsies, aid in cytological analy-sis. With high diagnostic accuracy, safety, and therapeutic potential, EUS is able to improve patient outcomes when managing IAP. Further refinement of EUS techniques and cost-effectiveness assessment of EUS-guided approaches need to be explored in multicenter prospective studies. This review underscores EUS as a transformative tool in unraveling IAP's enigma and advancing diagnostic and therapeutic strategies.
ARTICLE | doi:10.20944/preprints201801.0046.v2
Subject: Medicine And Pharmacology, Dietetics And Nutrition Keywords: cholesterol synthesis; bile acid synthesis; cholesterol absorption; lathosterol; plant sterols; oxysterols; lipoproteins; lipid lowering; phytosterols; placebo
Online: 10 January 2018 (10:51:03 CET)
Chitosan treatment results in significantly lower serum LDL cholesterol concentrations. To assess the working mechanism of chitosan, we measured serum surrogate markers of cholesterol absorption (campesterol, sitosterol, cholestanol), synthesis (lathosterol, lanosterol, desmosterol), and degradation to bile acids (7α-hydroxy-cholesterol, 27-hydroxy-cholesterol) corrected for cholesterol concentration (R_sterols). Over 12 weeks, 116 obese subjects (BMI 31.7, range 28.1 – 38.9 kg/m2) were studied under chitosan (n=61) and placebo treatment (n=55). The participants were briefly educated regarding improvement of nutrition quality and energy expenditure. Daily chitosan intake was 3200 mg. Serum LDL cholesterol concentration decreased significantly more (P=0.0252) under chitosan (-8.67 ± 18.18 mg/dl, 5.6%) than under placebo treatment (-1.00 ± 24.22 mg/dl, 0.9%). This reduction was not associated with the expected greater decreases in markers of cholesterol absorption under chitosan treatment. Also, increase in markers of cholesterol synthesis and bile acid synthesis under chitosan treatment was not any greater than under placebo treatment. In conclusion, a significant selective reduction of serum LDL cholesterol under chitosan treatment is neither associated with a reduction of serum surrogate markers of cholesterol absorption nor with an increases of markers for cholesterol and bile acid synthesis.
ARTICLE | doi:10.20944/preprints202210.0164.v1
Subject: Chemistry And Materials Science, Physical Chemistry Keywords: conformation; steroid skeleton; surfactants; mixed micelles; bile salts; regular solution theory; thermodynamic stabilization; first neighbor intermolecular interactions
Online: 12 October 2022 (07:11:07 CEST)
Binary mixtures of surfactants build a binary mixed micelle in which the ratio of surfactants usually differs from the initial ratio of surfactants in their binary mixture. The thermodynamic stabilization of the binary mixed micellar pseudophase about the hypothetical ideal state (intermolecular interactions between the different particles and the conformational states of the particles are identical to those of monocomponent states) is described by the molar excess Gibbs free energy (gE). The dependence of gE on the molar fraction of surfactant i (xi) from the binary mixed micelle can be described by a symmetric function (symmetry is described to the line parallel to the y-axis and passes through xi = 0.5) or by an asymmetric function. Theoretical analysis (canonical partition function, conformational analysis) examines how the presence of different polar functional groups, some of which are sterically shielded from the steroid skeleton of bile salt (surfactant), affect the symmetry of the function gE of the binary mixed micelle of the cholic acid anion (bile salt) and classical cationic surfactant (hydrophobic tail and polar head). Suppose the steroid skeleton of the bile salt contains non-sterically shielded polar groups (or the temperature is relatively high). In that case, gE is a symmetric function. At the same time, if the steroid skeleton also contains sterically shielded polar groups, then the gE function is asymmetric.