UMLS:C0008370 - FACTA Search

Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0008370 (cholestasis)
9,378 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chloride-bicarbonate anion exchanger 2 (AE2) is expressed in a variety of tissues, including the liver and salivary glands, where it may participate in the generation of hydroionic fluxes into secretions. We have previously reported decreased hepatic levels of AE2 messenger RNA in patients with primary biliary cirrhosis (PBC), a cholestatic condition frequently associated with pluriglandular exocrine failure. Here we investigated the expression of AE2 protein in the liver of PBC patients. Using a monoclonal antibody against an AE2 peptide, immunohistochemistry was performed on liver biopsy specimens from subjects with normal liver (n = 7), patients with PBC (n = 13), and patients with cirrhosis or cholestasis other than PBC (n = 17 and 11, respectively). Immunostaining was graded from 0 to 7, according to its intensity and distribution. AE2 immunoreactivity was observed in normal livers, as previously reported, and in many pathological liver biopsy specimens, being mainly restricted to canaliculi and the luminal membrane of terminal and interlobular bile ducts. Canalicular and ductular scores were significantly reduced in the PBC group compared with each control group (normal liver and cirrhosis or cholestasis other than PBC), whereas no differences in immunoreactivity scores were observed among control groups. When four patients with primary sclerosing cholangitis (PSC) were analyzed, they also differed from those with PBC. These results suggest that PBC is characterized by diminished expression of AE2 in the liver. Reduced levels of this transporter protein might be involved in the pathogenesis of cholestasis in PBC.
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PMID:Decreased anion exchanger 2 immunoreactivity in the liver of patients with primary biliary cirrhosis. 898 58

Estradiol-17beta-D-glucuronide (E2-17G) induces an acute but reversible inhibition of bile flow after its intravenous administration to rats, due in part to the endocytic retrieval of the canalicular multidrug resistance-associated transporter protein 2 and the bile salt export pump, transporters that contribute to bile flow. Decreased bile salt-independent bile flow (BSIF) is also involved and persists during the phase of recovery from cholestasis. Because glutathione and HCO3- are major contributors to BSIF, we evaluated changes in their biliary excretion and the hepatic content of total glutathione during E2-17G-induced cholestasis. E2-17G acutely decreased bile flow and biliary excretion of total glutathione by about 80%; glutathione excretion was still inhibited at 80 min and 120 min, even though bile flow was partially and totally restored, respectively. Neither liver glutathione content nor the proportions of oxidized glutathione in bile and liver were affected by E2-17G at any time. HCO3- concentrations in bile were unchanged, so that secretion paralleled variations in bile flow. In the isolated perfused liver, addition of E2-17G decreased both bile flow and the biliary concentration of glutathione, whereas addition of its noncholestatic isomer estradiol-3-D-glucuronide (E2-3G) did not inhibit bile flow, but significantly reduced the concentration of glutathione in bile. The bile:liver concentration ratios of glutathione were significantly decreased in vivo by E2-17G and in the perfused liver by E2-17G and E2-3G. These data indicate that E2-17G cis-inhibits the canalicular transport of glutathione and thus contributes to the cholestatic effect by inhibiting BSIF.
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PMID:Biliary secretion of glutathione in estradiol 17beta-D-glucuronide-induced cholestasis. 1289 35

Recent progress has enhanced our understanding of the pathogenesis of cholestatic liver diseases. Mutations in genes encoding for hepatobiliary transport systems can cause hereditary cholestatic syndromes and exposure to cholestatic agents (drugs, hormones, inflammatory cytokines) can lead to reduced expression and function of hepatic uptake and excretory systems in acquired forms of cholestasis. In addition to transporter changes which cause or maintain cholestasis, some alterations in transporter gene expression can be viewed as hepatoprotective mechanisms aimed at reducing intrahepatic accumulation of toxic biliary constituents such as bile acids and bilirubin. Alternative excretion of bile acids via the basolateral membrane into the systemic circulation facilitates the renal elimination of bile acids into urine. Moreover, increased bile acid hydroxylation, sulfation and glucuronidation by phase I and II metabolizing enzymes renders bile acids more hydrophilic and less toxic. These molecular changes are mediated by specific nuclear receptors which are regulated by bile acids, proinflammatory cytokines, drugs, and hormones. In addition to transcriptional changes, reduced transporter protein insertion to or increased retrieval from the cell membrane as well as other mechanisms such as altered cell polarity, disruption of cell-to-cell junctions and cytoskeletal changes are involved in the pathogenesis of cholestasis. Understanding the detailed mechanisms regulating expression of transport systems and enzymes is essential for the development of novel therapeutic agents. Such future approaches could specifically target nuclear receptors thus restoring defective transporter expression and supporting hepatic defense mechanisms against toxic bile acids.
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PMID:Molecular mechanisms of cholestasis. 1693 39

Bile is a complex mixture that includes bile salts, the membrane phospholipid phosphatidylcholine (PC), cholesterol and various endobiotic and xenobiotic toxins, each of which is secreted across the canalicular membrane of the hepatocyte by different ATP-binding cassette (ABC) transporters. The bile salts are essential for the emulsification of dietary fat and lipophilic vitamins. They are synthesized from cholesterol in the hepatocyte and their secretion by the bile salt export pump (BSEP or ABCB11) drives bile flow and is the starting point for the enterohepatic cycle. The detergent nature of bile salts that is key to their physiological role also means that they are inherently cytotoxic, and failure to secrete bile (intraheptic cholestasis) can precipitate severe liver disease and mortality. Such progressive familial intrahepatic cholestasis (PFIC) comes in three types of autosomal recessive disease. PFIC2 is caused by mutation to ABCB11. PFIC3 is caused by mutation of a closely related ABC transporter, ABCB4, which flops PC into the outerleaflet of the canalicular membrane. The flopped PC is extracted by the bile salts in the canaliculus to form a mixed micelle that reduces bile salt detergent activity. The third protein that is essential for bile flow from the hepatocyte is a member of a different class of transporter protein, a P-type ATPase, ATP8B1. Mutation of ATP8B1 causes PFIC1, but ATP8B1 does not transport a component of bile into the canaliculus. Data from different laboratories, published this year, suggests two different roles for ATP8B1 in the hepatocyte: a lipid flippase, that counterbalances the deleterious effects of ABCB4 on barrier function of the canalicular membrane; and an anchor of the actin cytoskeleton necessary to form the microvilli of the brush border. These latest discoveries are described, along with a spectrum of cholestatic disorders whose aetiologies lie in these and other transporters of the canalicular membrane.
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PMID:Canalicular ABC transporters and liver disease. 2198 74

We describe a child with progressive familial intrahepatic cholestasis (PFIC) of type 2 inherited as uniparental isodisomy of chromosome 2. Bile salt export pump (BSEP) deficiency is a severe, genetically determined subtype PFIC caused by mutations in ABCB11, the gene encoding a bile salt transporter protein. Clinical and pathological diagnosis in PFIC2 is corroborated by an ample array of ABCB11 mutations, inherited in an autosomal recessive fashion. We report clinical, pathological, and molecular studies in a child with PFIC2. A 5.5-year-old boy harbored a described pathogenic mutation (p.R832C) in ABCB11. The mutation was found to be homozygous in the patient and heterozygous in DNA from paternal, but not maternal blood. Having ruled out maternal gene deletion and somatic mosaicism, we showed that the child had inherited an isodisomic paternal chromosome 2, including the 2q31.1 region where ABCB11 is located. The present report is the first description of uniparental isodisomy in a hepatic heritable disorder. Recognizing isodisomic transmission may have a significant impact on genetic counseling helping to define the risk of recurrence in subsequent pregnancies.
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PMID:Paternal isodisomy of chromosome 2 in a child with bile salt export pump deficiency. 2236 1

Adverse outcome pathways (AOPs) have been recently introduced in human risk assessment as pragmatic tools with multiple applications. As such, AOPs intend to provide a clear-cut mechanistic representation of pertinent toxicological effects. AOPs are typically composed of a molecular initiating event, a series of intermediate steps and key events, and an adverse outcome. In this study, an AOP framework is proposed for cholestasis triggered by drug-mediated inhibition of the bile salt export pump transporter protein. For this purpose, an in-depth survey of relevant scientific literature was carried out in order to identify intermediate steps and key events. The latter include bile accumulation, the induction of oxidative stress and inflammation, and the activation of specific nuclear receptors. Collectively, these mechanisms drive both a deteriorative cellular response, which underlies directly caused cholestatic injury, and an adaptive cellular response, which is aimed at counteracting cholestatic insults. AOP development was performed according to Organisation for Economic Co-operation and Development (OECD) guidance, including critical consideration of the Bradford Hill criteria for weight of evidence assessment and the OECD key questions for evaluating AOP confidence. The postulated AOP is expected to serve as the basis for the development of new in vitro tests and the characterization of novel biomarkers of drug-induced cholestasis.
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PMID:Development of an adverse outcome pathway from drug-mediated bile salt export pump inhibition to cholestatic liver injury. 2394

The ATP-binding cassette (ABC) transporter A subfamily 8 (ABCA8) belongs to the ABCA6-like transporters subgroup, which is distinct from the ABCA1-like subgroup in the ABCA family. The expression and function of the short-size human ABCA8 lacking one of the two ATP-binding domains for ATP hydrolysis, which are regularly present in the other ABCA transporters, have been reported. However, the functional differences between the short-size human ABCA8 and full-size human ABCA8, which has the two ATP-binding domains, remain unknown. The purpose of the present study was to clarify the tissue expression profiles of ABCA6-like and ABCA1-like subgroup transporters and the functional characteristics of ABCA8 in mouse and human. The tissue distribution of mouse ABCA (mABCA) transporter protein and the changes in mABCA8 protein expression levels in a mouse model of obstructive cholestasis were elucidated by means of quantitative targeted absolute proteomics (QTAP). The transport characteristics were clarified in a HEK293 cell line overexpressing full-size ABCA8 protein. QTAP and immunohistochemical analyses revealed that mABCA transporters exhibited the distinct protein expression patterns in the tissues, and mABCA8b, its mouse orthologue, was abundant in the liver and predominantly distributed in sinusoidal membranes of the hepatocytes. Further, protein expression of mABCA8b was decreased in the mouse cholestasis liver. Changes of mABCA8b expression level in cholestasis were similar to those of mABCA1, a sinusoidal cholesterol efflux transporter. Uptake and efflux assays showed that ABCA8 mediates efflux of [³H]cholesterol and [³H]taurocholate, while it showed no significant efflux activity for [³H]estrone sulfate, [³H]digoxin, [³H]vinblastine, [³H]para-aminohippuric acid, [³H]oleic acid, [¹⁴C]nicotine, or [³H]methotrexate. [³H]Cholesterol efflux was increased by extracellularly applied taurocholate. These results suggest that mABCA8b/ABCA8 functions as a sinusoidal efflux transporter for at least cholesterol and taurocholate in mouse and human liver.
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PMID:ATP-Binding Cassette Transporter A Subfamily 8 Is a Sinusoidal Efflux Transporter for Cholesterol and Taurocholate in Mouse and Human Liver. 2930 Apr 88

Cholagogic traditional Chinese medicines refer to those that can promote bile secretion and excretion, strengthen gallbladder contraction and promote gallbladder emptying. They are mainly used to treat cholecystitis, gallstones, cholestasis, biliary tract infection, jaundice hepatitis and other diseases in clinical application. As a traditional medicine in our country, Chinese herbal medicines have many advantages, such as extensive resources, low cost, little or no toxic and side effects, and in addition, it is not easy for animals to produce drug resistance. With the progress of science and technology and the rapid development of traditional Chinese medicine, many achievements have been made in the research of cholagogic traditional Chinese medicines. Traditional Chinese medicine plays a cholagogic role mainly by promoting bile secretion, regulating SCP2 mRNA, FXR, BSEP and efflux transporter protein, dissolving cholesterol, promoting the relaxation of Oddi's sphincter and changing the composition of bile, etc. Traditional Chinese medicine decoction, traditional Chinese medicine preparation, Chinese medicine combined with acupuncture, ear acupoint pressing, soaking bath, western medicine and alike are often used to treat biliary system diseases in clinical practice. The effective rate of combination of traditional Chinese medicine and other methods was significantly higher than that of compound prescription, western medicine, acupuncture and soaking bath alone. General attack therapy and new therapies are also used in clinical treatment. The clinical effect of traditional Chinese medicine is remarkable. By means of literature review, the pharmacological effects, mechanism and clinical application of Chinese herbal medicines and compound prescriptions with gallbladder-promoting effect in the past 15 years were summarized in this paper. At the same time, some existing problems were found and prospects were expected.
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PMID:[Advances in research of traditional Chinese medicine for promoting bile secretion and excretion]. 3228 38