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Dulko D, Kłosowska-Chomiczewska IE, Del Castillo-Santaella T, Cabrerizo-Vílchez MA, Łuczak J, Staroń R, Krupa Ł, Maldonado-Valderrama J, Macierzanka A. Interfacial behaviour of human bile and its substitution for in vitro lipolysis studies. Food Res Int 2024; 197:115203. [PMID: 39593288 DOI: 10.1016/j.foodres.2024.115203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2024] [Revised: 09/14/2024] [Accepted: 10/17/2024] [Indexed: 11/28/2024]
Abstract
This study examined the interfacial evolution of individual bile salts (BSs) and their blends with phosphatidylcholine (BS/PC) to simulate the complex behaviour of human bile (HB) during lipolysis at the triglyceride/water interface. Using adsorption and desorption cycles, mimicking exposure to small intestinal fluids, we demonstrate that the interfacial behaviour of real HB can be replicated using simple mixtures of BSs and PC. Interfacial tension (IFT) measurements after lipolysis and desorption showed no significant differences (P > 0.05) between HB samples and BS/PC mixtures across the total BS concentrations analysed (2.23-7.81 mM). However, individual BSs without PC yielded significantly different IFT results (P < 0.01) compared to HB, highlighting the importance of phospholipids. Dilatation rheology further emphasised the need for accurate phospholipid representation in bile models. Our results suggest that phospholipids in HB and in BS/PC systems enhance resistance to desorption, potentially affecting lipolysis. This is important, as current in vitro digestion models often replicate only intestinal BS concentrations to mimic the behaviour of HB in the intestinal lumen. Furthermore, the specific composition of BSs in HB appears less critical than the overall BS and phospholipid contents, suggesting that the kinetics of triglyceride digestion is influenced by the combined luminal concentrations of these components. These findings have significant implications for understanding the role of bile in digestion and offer insights for designing more accurate in vitro models to study the gastrointestinal behaviour of food emulsions and lipid-based delivery systems.
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Affiliation(s)
- Dorota Dulko
- Department of Biotechnology and Microbiology, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Ilona E Kłosowska-Chomiczewska
- Department of Biotechnology and Microbiology, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland.
| | | | | | - Justyna Łuczak
- Department of Process Engineering and Chemical Technology, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland.
| | - Robert Staroń
- Department of Gastroenterology and Hepatology with Internal Disease Unit, Specialist University Hospital Frederic Chopin, Rzeszów, Poland; Medical Department, University of Rzeszów, Rzeszów, Poland
| | - Łukasz Krupa
- Department of Gastroenterology and Hepatology with Internal Disease Unit, Specialist University Hospital Frederic Chopin, Rzeszów, Poland; Medical Department, University of Rzeszów, Rzeszów, Poland
| | | | - Adam Macierzanka
- Department of Biotechnology and Microbiology, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland.
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Kłosowska K, Del Castillo-Santaella T, Maldonado-Valderrama J, Macierzanka A. The bile salt/phospholipid ratio determines the extent of in vitro intestinal lipolysis of triglycerides: Interfacial and emulsion studies. Food Res Int 2024; 187:114421. [PMID: 38763671 DOI: 10.1016/j.foodres.2024.114421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 04/19/2024] [Accepted: 04/22/2024] [Indexed: 05/21/2024]
Abstract
This study focused on the protein-stabilised triglyceride (TG)/water interfaces and oil-in-water emulsions, and explored the influence of varying molar ratios of bile salts (BSs) and phospholipids (PLs) on the intestinal lipolysis of TGs. The presence of these two major groups of biosurfactants delivered with human bile to the physiological environment of intestinal digestion was replicated in our experiments by using mixtures of individual BSs and PLs under in vitro small intestinal lipolysis conditions. Conducted initially, retrospective analysis of available scientific literature revealed that an average molar ratio of 9:4 for BSs to PLs (BS/PL) can be considered physiological in the postprandial adult human small intestine. Our experimental data showed that combining BSs and PLs synergistically enhanced interfacial activity, substantially reducing oil-water interfacial tension (IFT) during interfacial lipolysis experiments with pancreatic lipase, especially at the BS/PL-9:4 ratio. Other BS/PL molar proportions (BS/PL-6.5:6.5 and BS/PL-4:9) and an equimolar amount of BSs (BS-13) followed in IFT reduction efficiency, while using PLs alone as biosurfactants was the least efficient. In the following emulsion lipolysis experiments, BS/PL-9:4 outperformed other BS/PL mixtures in terms of enhancing the TG digestion extent. The degree of TG conversion and the desorption efficiency of interfacial material post-lipolysis correlated directly with the BS/PL ratio, decreasing as the PL proportion increased. In conclusion, this study highlights the crucial role of biliary PLs, alongside BSs, in replicating the physiological function of bile in intestinal lipolysis of emulsified TGs. Our results showed different contributions of PLs and BSs to lipolysis, strongly suggesting that any future in vitro studies aiming to simulate the human digestion conditions should take into account the impact of biliary PLs - not just BSs - to accurately mimic the physiological role of bile in intestinal lipolysis. This is particularly crucial given the fact that existing in vitro digestion protocols typically focus solely on applying specific concentrations and/or compositions of BSs to simulate the action of human bile during intestinal digestion, while overlooking the presence and concentration of biliary PLs under physiological gut conditions.
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Affiliation(s)
- Katarzyna Kłosowska
- Department of Colloid and Lipid Science, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland.
| | - Teresa Del Castillo-Santaella
- Department of Physical Chemistry, University of Granada, Faculty of Pharmacy, Campus de Cartuja s/n, 18071 Granada, Spain.
| | - Julia Maldonado-Valderrama
- Department of Applied Physics, University of Granada, Faculty of Sciences, Campus de Fuentenueva s/n, 18071 Granada, Spain.
| | - Adam Macierzanka
- Department of Colloid and Lipid Science, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland.
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3
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Dulko D, Staroń R, Krupa L, Rigby NM, Mackie AR, Gutkowski K, Wasik A, Macierzanka A. The bile salt content of human bile impacts on simulated intestinal proteolysis of β-lactoglobulin. Food Res Int 2021; 145:110413. [PMID: 34112416 DOI: 10.1016/j.foodres.2021.110413] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 03/27/2021] [Accepted: 05/08/2021] [Indexed: 12/12/2022]
Abstract
The gastrointestinal hydrolysis of food proteins has been portrayed in scientific literature to predominantly depend on the activity and specificity of proteolytic enzymes. Human bile has not been considered to facilitate proteolysis in the small intestine, but rather to assist in intestinal lipolysis. However, human bile can potentially influence proteins that are largely resistant to gastric digestion, and which are mainly hydrolysed after they have been transferred to the small intestine. We used purified and food-grade bovine milk β-lactoglobulin (βLg) to assess the impact of bile salts (BS) on the in vitro gastrointestinal digestion of this protein. Quantitative analysis showed that the proteolysis rate increased significantly with increasing BS concentration. The effect was consistent regardless of whether individual BS or real human bile samples, varying in BS concentrations, were used. The total BS content of bile was more important than its BS composition in facilitating the proteolysis of βlg. We also show that the impact of human bile observed during the digestion of purified βLg and βLg-rich whey protein isolate can be closely replicated by the use of individual BS mixed with phosphatidylcholine. This could validate simple BS/phosphatidylcholine mixtures as human-relevant substitutes of difficult-to-obtain human bile for in vitro proteolysis studies.
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Affiliation(s)
- Dorota Dulko
- Gdańsk University of Technology, Faculty of Chemistry, Department of Colloid and Lipid Science, Gabriela Narutowicza 11/12, 80-322 Gdańsk, Poland
| | - Robert Staroń
- Department of Gastroenterology and Hepatology with Internal Disease Unit, Teaching Hospital No 1, Chopina 2, 35-055 Rzeszów, Poland
| | - Lukasz Krupa
- Department of Gastroenterology and Hepatology with Internal Disease Unit, Teaching Hospital No 1, Chopina 2, 35-055 Rzeszów, Poland
| | - Neil M Rigby
- University of Leeds, School of Food Science and Nutrition, Leeds LS2 9JT, United Kingdom
| | - Alan R Mackie
- University of Leeds, School of Food Science and Nutrition, Leeds LS2 9JT, United Kingdom
| | - Krzysztof Gutkowski
- Department of Gastroenterology and Hepatology with Internal Disease Unit, Teaching Hospital No 1, Chopina 2, 35-055 Rzeszów, Poland
| | - Andrzej Wasik
- Gdańsk University of Technology, Faculty of Chemistry, Department of Analytical Chemistry, Gabriela Narutowicza 11/12, 80-322 Gdańsk, Poland
| | - Adam Macierzanka
- Gdańsk University of Technology, Faculty of Chemistry, Department of Colloid and Lipid Science, Gabriela Narutowicza 11/12, 80-322 Gdańsk, Poland.
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4
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Cholesterol-phospholipid interactions resist the detergent effect of bovine bile. Colloids Surf B Biointerfaces 2021; 205:111842. [PMID: 34022699 DOI: 10.1016/j.colsurfb.2021.111842] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 05/02/2021] [Accepted: 05/08/2021] [Indexed: 12/29/2022]
Abstract
Sphingomyelin (SM) and cholesterol complexation gives rise to detergent-resistant liquid-ordered domains. The persistence of these domains and subsequent mixed micelle formation was examined in the presence of bile under physiological digestive in vitro conditions for vesicles comprising either SM/cholesterol, porcine brain phosphatidylcholine (BPC)/cholesterol, or soy phosphatidylcholine (SPC)/cholesterol bilayers, the latter two systems having no liquid-ordered domains. Micellization of these digested phospholipid multilamellar vesicle systems was confirmed by transmission electron microscopy. Bovine bile was found to consist of large multilamellar sheets which subsumed phospholipid vesicles to form aggregated superstructures. Budding off from these superstructures were vesicle-to-micelle transition intermediates: unilamellar vesicles and cylindrical micelles. The presence of cholesterol (60/40 phospholipid/cholesterol mol/mol) delayed the initial rapid onset of digestion, but not for BPC and SPC vesicle systems. Acyl chain order/disorder before and after vesicle-to-micelle transition of all three phospholipid/cholesterol systems was examined using Raman spectroscopy. The addition of bovine bile to both PC/cholesterol vesicle systems reduced the overall ratio of acyl chain disorder to order. In SM/cholesterol vesicles with ≤ 20% mol cholesterol, only the lateral inter-acyl chain packing was reduced, whereas for SM/cholesterol vesicles with ≥ 30% mol cholesterol, a higher proportion of gauche-to-trans isomerization was apparent, demonstrating that SM/cholesterol complexes modify the acyl chain structure of micelles.
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Ikeda Y, Morita SY, Hatano R, Tsuji T, Terada T. Enhancing effect of taurohyodeoxycholate on ABCB4-mediated phospholipid efflux. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:1495-1502. [PMID: 31176036 DOI: 10.1016/j.bbalip.2019.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/30/2019] [Accepted: 06/01/2019] [Indexed: 11/27/2022]
Abstract
Hydrophilic bile salts, ursodeoxycholate and hyodeoxycholate, have choleretic effects. ABCB4, a member of the ABC transporter family, is essential for the secretion of phospholipids from hepatocytes into bile. In this study, we assessed the effects of taurine- or glycine-conjugated cholate, ursodeoxycholate and hyodeoxycholate on the ABCB4-mediated phosphatidylcholine (PC) efflux using Abcb4 knockout mice and HEK293 cells stably expressing ABCB4. To evaluate the effects of bile salts on bile formation in Abcb4+/+ or Abcb4-/- mice, the bile was collected during intravenous infusion of saline or bile salts. The biliary PC secretion in Abcb4+/+ mice was significantly increased by the infusions of all tested bile salts, especially taurohyodeoxycholate. On the other hand, Abcb4-/- mice exhibited extremely low secretion of PC into bile, which was not altered by bile salt infusions. We also showed that the PC efflux from ABCB4-expressing HEK293 cells was stimulated by taurohyodeoxycholate much more strongly than the other tested bile salts. However, taurohyodeoxycholate did not restore the activities of ABCB4 mutants. Furthermore, light scattering measurements demonstrated a remarkable ability of taurohyodeoxycholate to form mixed micelles with PC. Therefore, the enhancing effect of taurohyodeoxycholate on the ABCB4-mediated PC efflux may be due to the strong mixed micelle formation ability.
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Affiliation(s)
- Yoshito Ikeda
- Department of Pharmacy, Shiga University of Medical Science Hospital, Otsu City, Shiga 520-2192, Japan
| | - Shin-Ya Morita
- Department of Pharmacy, Shiga University of Medical Science Hospital, Otsu City, Shiga 520-2192, Japan.
| | - Ryo Hatano
- Department of Medical Physiology, Graduate School of Medicine, Chiba University, Chuo-ku, Chiba 260-8670, Japan
| | - Tokuji Tsuji
- Department of Pharmacy, Shiga University of Medical Science Hospital, Otsu City, Shiga 520-2192, Japan
| | - Tomohiro Terada
- Department of Pharmacy, Shiga University of Medical Science Hospital, Otsu City, Shiga 520-2192, Japan
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6
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Morita SY, Ikeda Y, Tsuji T, Terada T. Molecular Mechanisms for Protection of Hepatocytes against Bile Salt Cytotoxicity. Chem Pharm Bull (Tokyo) 2019; 67:333-340. [DOI: 10.1248/cpb.c18-01029] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Shin-ya Morita
- Department of Pharmacy, Shiga University of Medical Science Hospital
| | - Yoshito Ikeda
- Department of Pharmacy, Shiga University of Medical Science Hospital
| | - Tokuji Tsuji
- Department of Pharmacy, Shiga University of Medical Science Hospital
| | - Tomohiro Terada
- Department of Pharmacy, Shiga University of Medical Science Hospital
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7
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Ikeda Y, Morita SY, Terada T. Cholesterol attenuates cytoprotective effects of phosphatidylcholine against bile salts. Sci Rep 2017; 7:306. [PMID: 28331225 PMCID: PMC5428433 DOI: 10.1038/s41598-017-00476-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 02/27/2017] [Indexed: 01/03/2023] Open
Abstract
Bile salts have potent detergent properties and damaging effects on cell membranes, leading to liver injury. However, the molecular mechanisms for the protection of hepatocytes against bile salts are not fully understood. In this study, we demonstrated that the cytotoxicity of nine human major bile salts to HepG2 cells and primary human hepatocytes was prevented by phosphatidylcholine (PC). In contrast, cholesterol had no direct cytotoxic effects but suppressed the cytoprotective effects of PC. PC reduced the cell-association of bile salt, which was reversed by cholesterol. Light scattering measurements and gel filtration chromatography revealed that cholesterol within bile salt/PC dispersions decreased mixed micelles but increased vesicles, bile salt simple micelles and monomers. These results suggest that cholesterol attenuates the cytoprotective effects of PC against bile salts by facilitating the formation of bile salt simple micelles and monomers. Therefore, biliary PC and cholesterol may play different roles in the pathogenesis of bile salt-induced liver injury.
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Affiliation(s)
- Yoshito Ikeda
- Department of Pharmacy, Shiga University of Medical Science Hospital, Otsu City, Shiga, 520-2192, Japan
| | - Shin-Ya Morita
- Department of Pharmacy, Shiga University of Medical Science Hospital, Otsu City, Shiga, 520-2192, Japan.
| | - Tomohiro Terada
- Department of Pharmacy, Shiga University of Medical Science Hospital, Otsu City, Shiga, 520-2192, Japan
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8
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Levinger NE, Costard R, Nibbering ETJ, Elsaesser T. Ultrafast energy migration pathways in self-assembled phospholipids interacting with confined water. J Phys Chem A 2011; 115:11952-9. [PMID: 21928826 DOI: 10.1021/jp206099a] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Phospholipids self-assembled into reverse micelles in benzene are introduced as a new model system to study elementary processes relevant for energy transport in hydrated biological membranes. Femtosecond vibrational spectroscopy gives insight into the dynamics of the antisymmetric phosphate stretching vibration ν(AS)(PO(2))(-), a sensitive probe of local phosphate-water interactions and energy transport. The decay of the ν(AS)(PO(2))(-) mode with a 300-fs lifetime transfers excess energy to a subgroup of phospholipid low-frequency modes, followed by redistribution among phospholipid vibrations within a few picoseconds. The latter relaxation is accelerated by adding a confined water pool, an efficient heat sink in which the excess energy induces weakening or breaking of water-water and water-phospholipid hydrogen bonds. In parallel to vibrational relaxation, resonant energy transfer between ν(AS)(PO(2))(-) oscillators delocalizes the initial excitation.
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Affiliation(s)
- Nancy E Levinger
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, D-12489 Berlin, Germany.
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9
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Weihs D, Schmidt J, Danino D, Goldiner I, Leikin-Gobbi D, Eitan A, Rubin M, Talmon Y, Konikoff FM. A comparative study of microstructural development in paired human hepatic and gallbladder biles. Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1771:1289-98. [PMID: 17913578 DOI: 10.1016/j.bbalip.2007.07.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Revised: 07/22/2007] [Accepted: 07/26/2007] [Indexed: 10/23/2022]
Abstract
Cholesterol gallstones usually develop in the gallbladder and rarely form in bile ducts even in patients with highly lithogenic bile. Bile concentration and proteins (e.g. mucin) may affect crystallization, but the exact nature of this effect, especially in relation to crystallization pathways and microstructural evolution remains unclear. We examined lipid microstructures in paired hepatic and gallbladder biles to reveal ones that are essential for crystallization. Combining digital light microscopy with cryogenic-temperature transmission electron microscopy we are able to directly visualize and compare the time evolution of lipid microstructures in paired hepatic, gallbladder and diluted gallbladder biles of gallstone patients and controls, without drying or separating. Gallbladder bile exhibited several multilamellar vesicles and spheroidal micelles preceding and throughout crystallization. Vesicle morphology changed before crystallization was observed. In contrast, hepatic bile revealed almost no crystallization and while a variety of unilamellar vesicles and spheroidal micelles existed throughout the examination, multilamellar vesicles were rare. Diluted gallbladder bile was different from native gallbladder bile, as well as the paired hepatic bile, yielding occasional crystallization. Our findings suggest that maturing multilamellar vesicles precede (and at least partially initiate) crystallization in gallbladder bile. Although microstructural development seems to be concentration dependent, dilution of gallbladder bile to hepatic bile concentrations neither makes it identical to hepatic bile, nor prevents crystallization.
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Affiliation(s)
- Daphne Weihs
- Faculty of Chemical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel.
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10
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Kosters A, Kunne C, Looije N, Patel SB, Oude Elferink RPJ, Groen AK. The mechanism of ABCG5/ABCG8 in biliary cholesterol secretion in mice. J Lipid Res 2006; 47:1959-66. [PMID: 16741293 PMCID: PMC1805467 DOI: 10.1194/jlr.m500511-jlr200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The main player in biliary cholesterol secretion is the heterodimeric transporter complex, ABCG5/ABCG8, the function of which is necessary for the majority of sterols secreted into bile. It is not clear whether the primary step in this process is flopping of cholesterol from the inner to the outer leaflet of the canalicular membrane, with desorption by mixed micelles, or decreasing of the activation energy required for cholesterol desorption from the outer membrane leaflet. In this study, we investigated these mechanisms by infusing Abcg8(+/+), Abcg8(+/-), and Abcg8(-/-) mice with hydrophilic and hydrophobic bile salts. In Abcg8(-/-) mice, this failed to substantially stimulate biliary cholesterol secretion. Infusion of the hydrophobic bile salt taurodeoxycholate also resulted in cholestasis, which was induced in Abcg8(-/-) mice at a much lower infusion rate compared with Abc8(-/-) and Abcg8(+/-) mice, suggesting a reduced cholesterol content in the outer leaflet of the canalicular membrane. Indeed, isolation of canalicular membranes revealed a reduction of 45% in cholesterol content under these conditions in Abcg8(-/-) mice. Our data support the model that ABCG5/ABCG8 primarily play a role in flopping cholesterol (and sterols) from the inner leaflet to the outer leaflet of the canalicular membrane.
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Affiliation(s)
- Astrid Kosters
- AMC Liver Center, Academic Medical Center, Amsterdam, The Netherlands.
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11
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Kakorin S, Brinkmann U, Neumann E. Cholesterol reduces membrane electroporation and electric deformation of small bilayer vesicles. Biophys Chem 2005; 117:155-71. [PMID: 15923075 DOI: 10.1016/j.bpc.2005.05.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2005] [Revised: 05/04/2005] [Accepted: 05/04/2005] [Indexed: 11/27/2022]
Abstract
Electric fields, similar in the order of magnitude of the natural membrane fields of cellular lipid/protein membranes, and chemical relaxation spectrometry can be used as tools to quantify the rigidifying effect of cholesterol in membranes. Small unilamellar vesicles of radius a=50+/-3 nm, prepared form phosphatidylcholine, phosphatidylserine and phosphatidyl-glycerol in the molar ratio 1:1:1 and containing the optical lipid probe molecule 2-(3-diphenyl-hexatrienyl) propanoyl)-1-palmitoyl-sn-glycerol-3-phosphocholine (beta-DPH pPC), serve as examples for curved lipid membranes. The data of electrooptical turbidity and absorbance relaxations at the wavelength lambda=365 nm are analysed in terms of membrane bending rigidity kappa and membrane stretching modulus K. Both kappa and K increase with increasing mole fraction x of cholesterol up to x=0.5. The cholesterol induced denser packing of the lipids reduces the extent of both membrane electroporation (ME) and electroelongation of the vesicles. Further on, cholesterol in the lipid phase and sucrose in the aqueous suspension reduce the extent of membrane undulation and electro-stretching.
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Affiliation(s)
- Sergej Kakorin
- Physical and Biophysical Chemistry, Faculty of Chemistry, University of Bielefeld, P.O. Box 100 131, D-33501 Bielefeld, Germany
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12
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Kirana C, Rogers PF, Bennett LE, Abeywardena MY, Patten GS. Naturally derived micelles for rapid in vitro screening of potential cholesterol-lowering bioactives. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2005; 53:4623-7. [PMID: 15913335 DOI: 10.1021/jf050447x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
A high plasma cholesterol level, especially low-density lipoprotein cholesterol, indicates increased risk of cardiovascular diseases. Plasma cholesterol levels are influenced by diet and cholesterol biosynthesis, uptake, and secretion. Cholesterol uptake involves solubilization into complex phospholipid spherical bodies termed micelles that facilitate the transport of lipids through the gut brush border membrane into enterocytes. In vitro assays reported to date to determine potential cholesterol-lowering effects of various compounds require artificial micelle preparations that are elaborate and time-consuming to prepare. The aims of this study were to compare the efficacy of artificially prepared micelles with naturally derived micelles from pig's bile and to test their ability to assess potential inhibitors of cholesterol uptake. The suitability of pig's bile-derived micelles was tested both at the level of the micelle and at cellular uptake using cultured Caco-2 cells. Known cholesterol uptake inhibitors at the micelle (green tea catechins) and at the Caco-2 cell (beta-lactoglobulin-derived peptide, IIAEK) were used as reference inhibitory compounds. It was concluded that pig's bile was a rapid, reproducible, convenient, and cost-effective source of micelles for cholesterol micelle solubility and cellular uptake assay systems and is suitable for screening purposes focused on identifying potential cholesterol-lowering agents.
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Affiliation(s)
- Chandra Kirana
- Department of Biology, Faculty of Mathematics and Natural Sciences, Brawijaya University, Jl. Veteran Malang East Java, 65145, Indonesia.
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13
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Gudheti MV, Gonzalez YI, Lee SP, Wrenn SP. Interaction of apolipoprotein A-I with lecithin-cholesterol vesicles in the presence of phospholipase C. Biochim Biophys Acta Mol Cell Biol Lipids 2003; 1635:127-41. [PMID: 14729075 DOI: 10.1016/j.bbalip.2003.11.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Here we study the anti-nucleating mechanism of apolipoprotein A-I (apo A-I) on model biliary vesicles in the presence of phospholipase C (PLC) utilizing dynamic light scattering (DLS), steady-state fluorescence spectroscopy, cryogenic transmission electron microscopy (cryo-TEM), and UV/Vis spectroscopy. PLC induces aggregation of cholesterol-free lecithin vesicles from an initial, average size of 100 nm to a maximal size of 600 nm. The presence of apo A-I likely inhibits vesicle aggregation by shielding the PLC-generated hydrophobic moieties, which results in vesicles of an average size of 200 nm. A similar phenomenon is observed in cholesterol-enriched lecithin vesicles. Whereas PLC alone produces aggregates of 300 nm, no aggregation is observed when apo A-I is present along with PLC. However, the ability of apo A-I to inhibit aggregation is temporary, and after 8 h, a broad particle size distribution with sizes as high as 800 nm is observed. Apo A-I possibly induces the formation of small apo A-I/lecithin/cholesterol complexes of about 5-20 nm similar to the discoidal pre-HDL complexes found in blood when it can no longer effectively shield all the DAG molecules. Concomitant with formation of complexes, DAG molecules coalesce into large oil droplets, which account for the large particles observed by light scattering. Thus, apo A-I acts as an anti-nucleating agent by two mechanisms, anti-aggregation and microstructural transition. The mode of protection is dependent on the cholesterol content and the relative amounts of DAG and apo A-I present. This study supports the possibility of apo A-I solubilizing lipids in bile in a similar fashion as it does in blood and also delineates the mechanism of formation of the complexes.
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Affiliation(s)
- Manasa V Gudheti
- Department of Chemical Engineering, College of Engineering, Drexel University, Philadelphia, PA 19104, USA
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14
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Lyons MA, Wittenburg H, Li R, Walsh KA, Leonard MR, Churchill GA, Carey MC, Paigen B. New quantitative trait loci that contribute to cholesterol gallstone formation detected in an intercross of CAST/Ei and 129S1/SvImJ inbred mice. Physiol Genomics 2003; 14:225-39. [PMID: 12837957 DOI: 10.1152/physiolgenomics.00073.2003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Cholesterol gallstone formation is a response to interactions between multiple genes and environmental stimuli. To determine the subset of cholesterol gallstone susceptibility (Lith) genes possessed by strains CAST/Ei (susceptible) and 129S1/SvImJ (resistant), we conducted quantitative trait locus (QTL) analyses of an intercross between these strains. Parental strains and F(1) mice of both genders were evaluated for gallstone formation after consumption of a lithogenic diet for 8 wk. Gallstone susceptibility of strain CAST was predominantly due to cholesterol hypersecretion. Male intercross offspring were genotyped and phenotyped for cholesterol gallstone formation after consumption of the lithogenic diet for 10 wk. Linkage analysis was performed using PSEUDOMARKER software. One significant, new QTL was detected and named Lith13 [chromosome (Chr) 5, 30 cM]. Statistical analyses and QTL fine mapping suggest this QTL may comprise two closely linked loci. We confirmed the presence of Lith6 (Chr 6). Suggestive QTL were detected on Chrs 1, 2, 5, 14, and 16. The QTL on Chrs 2 and 16 confirmed previously identified, suggestive QTL. Therefore, they were named Lith12 (101 cM) and Lith14 (42 cM), respectively. We identified candidate genes based on known function and location and performed mRNA expression analyses using both parental strains and intercross progeny for preliminary evaluation of their contributions to gallstone formation. Cebpb (Lith12), Pparg (Lith6), and Slc21a1 (Lith6) displayed expression differences. Our work continues to demonstrate the genetic complexity and to elucidate the pathophysiology of cholesterol gallstone formation. It should facilitate the development of new approaches for treating this common human disorder.
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Gilat T, Leikin-Frenkel A, Goldiner L, Laufer H, Halpern Z, Konikoff FM. Arachidyl amido cholanoic acid (Aramchol) is a cholesterol solubilizer and prevents the formation of cholesterol gallstones in inbred mice. Lipids 2001; 36:1135-40. [PMID: 11768158 DOI: 10.1007/s11745-001-0824-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
We have recently synthesized fatty acid bile acid conjugates (FABAC) that were able to reduce and retard cholesterol crystallization in model and human biles. When given orally, they prevented the formation of cholesterol crystals in the bile of hamsters. The aim of the present study was to determine whether the FABAC are cholesterol solubilizers, whether they can dissolve pre-existing crystals, whether they can prevent the formation of cholesterol gallstones, and to investigate the optimal type of bond between the fatty acid and bile acid. The presence of cholesterol crystals was determined by light microscopy, and the total crystal mass of precipitated crystals was measured by chemical means. Inbred (C57J/L) mice on a lithogenic diet were used to evaluate cholesterol crystal formation, dissolution, and gallstone formation in vivo. Arachidyl amido cholanoic acid (Aramchol) was the FABAC used in the present experiments. At equimolar amounts, the cholesterol-solubilizing capacity of Aramchol was higher than that of taurocholate and similar to that of phosphatidylcholine. The addition of Aramchol dissolved approximately 50% of pre-existing crystals in model bile solutions. The same phenomenon was demonstrated in human bile ex vivo, with a dose-response effect. All inbred mice developed cholesterol crystals in bile after 10-14 d on the lithogenic diet. Thereafter, supplementation of the diet with Aramchol progressively reduced the proportion of mice with crystals to 25% after 28 d. On the lithogenic diet, 100% of inbred mice developed cholesterol gallstones in the gallbladder by day 21. None of the mice whose diet was supplemented with 0.5 mg or 1.0 mg of Aramchol/d developed stones or crystals. FABAC are a new class of molecules that are cholesterol solubilizers and which are able to dissolve cholesterol crystals in bile. Upon oral administration, they dissolve pre-existing cholesterol crystals and prevent the formation of gallstones in gallstone-susceptible mice.
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Affiliation(s)
- T Gilat
- Department of Gastroenterology, Sourasky Tel Aviv Medical Center, and Sackler Faculty of Medicine, Tel Aviv University, Israel.
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16
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Voshol PJ, Minich DM, Havinga R, Elferink RP, Verkade HJ, Groen AK, Kuipers F. Postprandial chylomicron formation and fat absorption in multidrug resistance gene 2 P-glycoprotein-deficient mice. Gastroenterology 2000; 118:173-82. [PMID: 10611166 DOI: 10.1016/s0016-5085(00)70426-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS It has been proposed that biliary phospholipids fulfill specific functions in the absorption of dietary fat from the intestine, but the physiological significance has not been established. The aim of this study was to evaluate the role of biliary phospholipids in dietary fat absorption in vivo by using mice homozygous or heterozygous for disruption of the Mdr2 gene (Mdr2((-/-)), Mdr2((+/-))) and control (Mdr2((+/+))) mice. Mdr2((-/-)) mice do not secrete phospholipids and cholesterol into bile, and bile salt secretion is not impaired. Mdr2((+/-)) mice show only impaired (-40%) phospholipid secretion. METHODS Methods included an analysis of time dependency of intestinal uptake and plasma appearance of intragastrically administered (radiolabeled) triglycerides and measurement of 3-day fecal fat balance with low- and high-fat diets. RESULTS Intragastric administration of olive oil resulted in a rapid increase in plasma triglycerides in Mdr2((+/+)) and Mdr2((+/-)) but not in Mdr2((-/-)) mice. The "postprandial response" of plasma triglycerides could be partially restored in Mdr2((-/-)) mice by intraduodenal infusion of whole rat bile. After intragastric [(3)H]triolein administration in Triton WR1339-pretreated animals, the appearance of (3)H-triglycerides in plasma was reduced by 70% in Mdr2((-/-)) compared with Mdr2((+/+)) mice, excluding accelerated lipolysis as the cause of defective triglyceride response in Mdr2((-/-)) mice. (3)H-triglycerides accumulated in enterocytes in Mdr2((-/-)) mice. Surprisingly, the efficacy of fat absorption as derived from balance studies was not affected and was only minimally affected in Mdr2((-/-)) mice fed low (14 energy percent)- and high (35 energy percent)-fat diets, respectively (all >95%). CONCLUSIONS The results show that biliary lipid secretion is necessary for postprandial appearance in plasma of chylomicrons in vivo but not for quantitative absorption of dietary lipids.
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Affiliation(s)
- P J Voshol
- Groningen Institute for Drug Studies, Center for Liver, Digestive, and Metabolic Diseases, University Hospital Groningen, Groningen, The Netherlands.
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17
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Wrenn SP, Kaler EW, Lee SP. A fluorescence energy transfer study of lecithin-cholesterol vesicles in the presence of phospholipase C. J Lipid Res 1999. [DOI: 10.1016/s0022-2275(20)33391-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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18
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Partial replacement of bile salts causes marked changes of cholesterol crystallization in supersaturated model bile systems. Biochem J 1999. [PMID: 10333488 DOI: 10.1042/bj3400445] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cholesterol crystallization is a key step in gallstone formation and is influenced by numerous factors. Human bile contains various bile salts having different hydrophobicity and micelle-forming capacities, but the importance of lipid composition to bile metastability remains unclear. This study investigated the effect of bile salts on cholesterol crystallization in model bile (MB) systems. Supersaturated MB systems were prepared with an identical composition on a molar basis (taurocholate/phosphatidylcholine/cholesterol, 152 mM:38 mM: 24 mM), except for partial replacement of taurocholate (10, 20, and 30%) with various taurine-conjugated bile salts. Cholesterol crystallization was quantitatively estimated by spectrophotometrically measuring crystal-related turbidity and morphologically scanned by video-enhanced microscopy. After partial replacement of taurocholate with hydrophobic bile salts, cholesterol crystallization increased dose-dependently without changing the size of vesicles or crystal morphology and the rank order of crystallization was deoxycholate>chenodeoxycholate>cholate (control MB). All of the hydrophilic bile salts (ursodeoxycholate, ursocholate and beta-muricholate) inhibited cholesterol precipitation by forming a stable liquid-crystal phase, and there were no significant differences among the hydrophilic bile-salt species. Cholesterol crystallization was markedly altered by partial replacement of bile salts with a different hydrophobicity. Thus minimal changes in bile-salt composition may dramatically alter bile lipid metastability.
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19
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Gantz DL, Wang DQ, Carey MC, Small DM. Cryoelectron microscopy of a nucleating model bile in vitreous ice: formation of primordial vesicles. Biophys J 1999; 76:1436-51. [PMID: 10049325 PMCID: PMC1300121 DOI: 10.1016/s0006-3495(99)77304-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Because gallstones form so frequently in human bile, pathophysiologically relevant supersaturated model biles are commonly employed to study cholesterol crystal formation. We used cryo-transmission electron microscopy, complemented by polarizing light microscopy, to investigate early stages of cholesterol nucleation in model bile. In the system studied, the proposed microscopic sequence involves the evolution of small unilamellar to multilamellar vesicles to lamellar liquid crystals and finally to cholesterol crystals. Small aliquots of a concentrated (total lipid concentration = 29.2 g/dl) model bile containing 8.5% cholesterol, 22.9% egg yolk lecithin, and 68.6% taurocholate (all mole %) were vitrified at 2 min to 20 days after fourfold dilution to induce supersaturation. Mixed micelles together with a category of vesicles denoted primordial, small unilamellar vesicles of two distinct morphologies (sphere/ellipsoid and cylinder/arachoid), large unilamellar vesicles, multilamellar vesicles, and cholesterol monohydrate crystals were imaged. No evidence of aggregation/fusion of small unilamellar vesicles to form multilamellar vesicles was detected. Low numbers of multilamellar vesicles were present, some of which were sufficiently large to be identified as liquid crystals by polarizing light microscopy. Dimensions, surface areas, and volumes of spherical/ellipsoidal and cylindrical/arachoidal vesicles were quantified. Early stages in the separation of vesicles from micelles, referred to as primordial vesicles, were imaged 23-31 min after dilution. Observed structures such as enlarged micelles in primordial vesicle interiors, segments of bilayer, and faceted edges at primordial vesicle peripheries are probably early stages of small unilamellar vesicle assembly. A decrease in the mean surface area of spherical/ellipsoidal vesicles was correlated with the increased production of cholesterol crystals at 10-20 days after supersaturation by dilution, supporting the role of small unilamellar vesicles as key players in cholesterol nucleation and as cholesterol donors to crystals. This is the first visualization of an intermediate structure that has been temporally linked to the development of small unilamellar vesicles in the separation of vesicles from micelles in a model bile and suggests a time-resolved system for further investigation.
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Affiliation(s)
- D L Gantz
- Department of Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
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20
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Wüstner D, Pomorski T, Herrmann A, Müller P. Release of phospholipids from erythrocyte membranes by taurocholate is determined by their transbilayer orientation and hydrophobic backbone. Biochemistry 1998; 37:17093-103. [PMID: 9836604 DOI: 10.1021/bi981608b] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Bile salts mediate a specific release of phosphatidylcholine (PC) from the canalicular membrane into the bile fluid. We utilized human red blood cells (RBC) as a model system to study the release of endogenous phospholipids as well as phospholipid analogues from plasma membranes in the presence of the bile salt taurocholate (TC). Short- and long-chain fluorescent as well as spin-labeled analogues with various headgroups were chosen. RBC were labeled either on the exoplasmic or on the cytoplasmic leaflet with the analogues and incubated with various concentrations of TC. Analogues on the exoplasmic layer could be readily released by TC. Release was most efficient above the critical micellar concentration (CMC) of TC. Release was independent of the headgroup, but depended on the fatty acid chain length of the analogues; i.e., it was lower for long-chain than for short-chain labeled phospholipids. Analogues on the cytoplasmic leaflet were efficiently shielded from TC-mediated release. The preferential release of endogenous PC and sphingomyelin (SM) from the erythrocyte membrane above the CMC supports the conclusion that TC-mediated release of phospholipids occurs preferentially from the exoplasmic leaflet independent of their headgroup. However, the extent of release of endogenous phospholipids was significantly lower in comparison to that of analogues, endorsing the relevance of the hydrophobic backbone for bile salt mediated release of phospholipids. Implications for the mechanism of the release of PC from the canalicular membrane into the bile fluid are discussed.
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Affiliation(s)
- D Wüstner
- Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, Institut für Biologie/Biophysik, Invalidenstrasse 43, D-10115 Berlin, Germany
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21
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Accatino L, Pizarro M, Solís N, Koenig CS. Effects of diosgenin, a plant-derived steroid, on bile secretion and hepatocellular cholestasis induced by estrogens in the rat. Hepatology 1998; 28:129-40. [PMID: 9657105 DOI: 10.1002/hep.510280118] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Increased biliary secretion of cholesterol and lipid vesicles (unilamellae and multilamellae) induced by diosgenin (D), a plant-derived steroid, has cytoprotective effects in the rat liver subjected to obstructive cholestasis. In this study, our aims were to investigate the following: 1) the effects of D on the bile secretory process and on the cholestasis induced by estradiol-17beta-(beta-D-glucuronide) (E17G) or 17 alpha-ethynylestradiol (E) administration; 2) whether the potentially protective effects of D are related to D-induced increase of biliary cholesterol and lipid lamellae; and 3) whether D has other effects capable of modifying specific bile secretory processes or preventing the cholestatic effects of estrogens. Rats were fed a standard ground chow (control group) or chow containing D for 6 days. E17G was administered i.v. to control and D-fed rats and bile flow, bile salt output, and alkaline phosphatase excretion were examined. 17alpha-E was administered from days 4 to 6 to rats fed standard chow or chow plus D for 6 days and different functional parameters of the bile secretory process as well as the ultrastructure of hepatocytes and histochemistry of alkaline phosphatase and Mg2+-adenosine triphosphatase (ATPase) were examined. D-treatment markedly increased cholesterol and lamellar structures in bile and attenuated the acute cholestatic effects of E17G. D-feeding prevented the decrease of taurocholate maximum secretory rate and the increase of biliary alkaline phosphatase and Ca2+,Mg2+-EctoATPase (EctoATPase) excretion, as well as the increase of cholesterol/ phospholipids ratio, alkaline phosphatase activity, and EctoATPase content in canalicular plasma membranes induced by E. D-feeding did not prevent E-induced decrease of basal bile flow, bile salt, cholesterol, and phospholipid secretory rates nor the decrease of Na+,K+-ATPase activity and Na+-taurocholate cotransporting polypeptide (Ntcp) content in isolated sinusoidal membranes. Cholestatic alterations of canalicular domain were apparent in E-treated rats. D administration was also associated with changes of ultrastructure and histochemistry of hepatocytes. E-induced alterations in ultrastructure and acinar distribution and intensity of histochemical reaction of both enzymes were partially prevented by D-feeding. We conclude that D administration, in addition to inducing a marked increase of biliary cholesterol and lipid lamellar structures output, was associated to changes in hepatocyte morphology and plasma membrane composition, enzymes activity, and histochemistry. D-feeding attenuated the acute cholestatic effects of E17G. D-induced increase of bile cholesterol and lipid lamellae content was not apparent when D-fed rats received E. Despite this fact, D administration prevented some cholestatic effects of E, probably through different metabolic effects and/or direct membrane effects, not related to increased lipid lamellae excretion.
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Affiliation(s)
- L Accatino
- Department of Gastroenterology, School of Medicine, Pontificia Universidad Católica de Chile, Santiago de Chile
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22
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Donovan JM, Jackson AA. Accurate separation of biliary lipid aggregates requires the correct intermixed micellar/intervesicular bile salt concentration. Hepatology 1998; 27:641-8. [PMID: 9500688 DOI: 10.1002/hep.510270301] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The intermixed micellar/intervesicular bile salt (BS) concentration (IMC), composed of BS monomers and simple micelles, is in dynamic equilibrium with mixed micelles and vesicles. Accurate separation of biliary lipid aggregates is believed to depend on accurately measuring the IMC. Using centrifugal ultrafiltration, we measured the IMC of cholesterol-supersaturated model biles that were physiologically composed. Gel chromatography was performed using eluants containing the following: 1) the IMC; 2) the same BS composition as the IMC but higher or lower BS concentrations; 3) the same BS concentration as the IMC, but with more hydrophilic or hydrophobic BS; and 4) 10 mmol/L cholate. Compared with an eluant containing the same BS composition as the IMC, an eluant containing the same relative BS composition but 75% of the IMC increased the proportion of cholesterol in vesicles and decreased the vesicular cholesterol/egg yolk phosphatidylcholine (EYPC) ratio. In contrast, an eluant containing 150% of the IMC entirely transformed vesicles to micelles. Eluants containing slightly more hydrophobic or more hydrophilic BS eliminated or increased vesicular cholesterol content, respectively. An eluant of 10 mmol/L cholate overestimated vesicular cholesterol and in concentrated biles reproducibly produced an incompletely separated intermediate peak, possibly because of re-equilibration between mixed micelles and vesicles. Further, in concentrated biles, fractions eluting at volumes corresponding to mixed micelles were visibly turbid, irrespective of the eluant used. The correct IMC allows accurate separation of biliary lipid aggregates, but differences in BS concentration or composition substantially alter the vesicular percentage of cholesterol as well as the cholesterol/EYPC ratio. Elution with 10 mmol/L cholate may introduce artifactual gel-filtration peaks and inadequate separation of particles with widely differing molecular weights, both of which have confused previous analyses of biliary lipid aggregates.
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Affiliation(s)
- J M Donovan
- Department of Medicine, Harvard Medical School, Boston, MA, USA
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23
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Lafont S, Rapaport H, Sömjen GJ, Renault A, Howes PB, Kjaer K, Als-Nielsen J, Leiserowitz L, Lahav M. Monitoring the Nucleation of Crystalline Films of Cholesterol on Water and in the Presence of Phospholipid. J Phys Chem B 1998. [DOI: 10.1021/jp973074e] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Sylvaine Lafont
- Department of Materials and Interfaces, Weizmann Institute of Science, 76100 Rehovot, Israel, Department of Gastroenterology, Souraski Medical Center, Ichilov Hospital, 6 Weizmann Street, 64239 Tel Aviv, and Minerva Center for Cholesterol Gallstones and Lipid Metabolism in the Liver, Sackler Faculty of Medicine, Tel Aviv University, Israel, Laboratoire de Spectrométrie Physique, UMR 5588 Université J. Fourier, BP 87, 38402 St. Martin d'Hères, France, Department of Solid State Physics, Risø National
| | - Hanna Rapaport
- Department of Materials and Interfaces, Weizmann Institute of Science, 76100 Rehovot, Israel, Department of Gastroenterology, Souraski Medical Center, Ichilov Hospital, 6 Weizmann Street, 64239 Tel Aviv, and Minerva Center for Cholesterol Gallstones and Lipid Metabolism in the Liver, Sackler Faculty of Medicine, Tel Aviv University, Israel, Laboratoire de Spectrométrie Physique, UMR 5588 Université J. Fourier, BP 87, 38402 St. Martin d'Hères, France, Department of Solid State Physics, Risø National
| | - Giora J. Sömjen
- Department of Materials and Interfaces, Weizmann Institute of Science, 76100 Rehovot, Israel, Department of Gastroenterology, Souraski Medical Center, Ichilov Hospital, 6 Weizmann Street, 64239 Tel Aviv, and Minerva Center for Cholesterol Gallstones and Lipid Metabolism in the Liver, Sackler Faculty of Medicine, Tel Aviv University, Israel, Laboratoire de Spectrométrie Physique, UMR 5588 Université J. Fourier, BP 87, 38402 St. Martin d'Hères, France, Department of Solid State Physics, Risø National
| | - Anne Renault
- Department of Materials and Interfaces, Weizmann Institute of Science, 76100 Rehovot, Israel, Department of Gastroenterology, Souraski Medical Center, Ichilov Hospital, 6 Weizmann Street, 64239 Tel Aviv, and Minerva Center for Cholesterol Gallstones and Lipid Metabolism in the Liver, Sackler Faculty of Medicine, Tel Aviv University, Israel, Laboratoire de Spectrométrie Physique, UMR 5588 Université J. Fourier, BP 87, 38402 St. Martin d'Hères, France, Department of Solid State Physics, Risø National
| | - Paul B. Howes
- Department of Materials and Interfaces, Weizmann Institute of Science, 76100 Rehovot, Israel, Department of Gastroenterology, Souraski Medical Center, Ichilov Hospital, 6 Weizmann Street, 64239 Tel Aviv, and Minerva Center for Cholesterol Gallstones and Lipid Metabolism in the Liver, Sackler Faculty of Medicine, Tel Aviv University, Israel, Laboratoire de Spectrométrie Physique, UMR 5588 Université J. Fourier, BP 87, 38402 St. Martin d'Hères, France, Department of Solid State Physics, Risø National
| | - Kristian Kjaer
- Department of Materials and Interfaces, Weizmann Institute of Science, 76100 Rehovot, Israel, Department of Gastroenterology, Souraski Medical Center, Ichilov Hospital, 6 Weizmann Street, 64239 Tel Aviv, and Minerva Center for Cholesterol Gallstones and Lipid Metabolism in the Liver, Sackler Faculty of Medicine, Tel Aviv University, Israel, Laboratoire de Spectrométrie Physique, UMR 5588 Université J. Fourier, BP 87, 38402 St. Martin d'Hères, France, Department of Solid State Physics, Risø National
| | - Jens Als-Nielsen
- Department of Materials and Interfaces, Weizmann Institute of Science, 76100 Rehovot, Israel, Department of Gastroenterology, Souraski Medical Center, Ichilov Hospital, 6 Weizmann Street, 64239 Tel Aviv, and Minerva Center for Cholesterol Gallstones and Lipid Metabolism in the Liver, Sackler Faculty of Medicine, Tel Aviv University, Israel, Laboratoire de Spectrométrie Physique, UMR 5588 Université J. Fourier, BP 87, 38402 St. Martin d'Hères, France, Department of Solid State Physics, Risø National
| | - Leslie Leiserowitz
- Department of Materials and Interfaces, Weizmann Institute of Science, 76100 Rehovot, Israel, Department of Gastroenterology, Souraski Medical Center, Ichilov Hospital, 6 Weizmann Street, 64239 Tel Aviv, and Minerva Center for Cholesterol Gallstones and Lipid Metabolism in the Liver, Sackler Faculty of Medicine, Tel Aviv University, Israel, Laboratoire de Spectrométrie Physique, UMR 5588 Université J. Fourier, BP 87, 38402 St. Martin d'Hères, France, Department of Solid State Physics, Risø National
| | - Meir Lahav
- Department of Materials and Interfaces, Weizmann Institute of Science, 76100 Rehovot, Israel, Department of Gastroenterology, Souraski Medical Center, Ichilov Hospital, 6 Weizmann Street, 64239 Tel Aviv, and Minerva Center for Cholesterol Gallstones and Lipid Metabolism in the Liver, Sackler Faculty of Medicine, Tel Aviv University, Israel, Laboratoire de Spectrométrie Physique, UMR 5588 Université J. Fourier, BP 87, 38402 St. Martin d'Hères, France, Department of Solid State Physics, Risø National
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24
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Crawford AR, Smith AJ, Hatch VC, Oude Elferink RP, Borst P, Crawford JM. Hepatic secretion of phospholipid vesicles in the mouse critically depends on mdr2 or MDR3 P-glycoprotein expression. Visualization by electron microscopy. J Clin Invest 1997; 100:2562-7. [PMID: 9366571 PMCID: PMC508457 DOI: 10.1172/jci119799] [Citation(s) in RCA: 125] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Hepatocellular secretion of bile salts into the biliary space induces phospholipid and cholesterol secretion, but the mechanism for integrated lipid secretion is poorly understood. Knockout mice unable to make the canalicular membrane mdr2 P-glycoprotein exhibit normal rates of bile salt secretion, yet are virtually incapable of secreting biliary phospholipid and cholesterol. As the mdr2 P-glycoprotein is thought to mediate transmembrane movement of phospholipid molecules, this mouse model was used to examine the mechanism for biliary phospholipid secretion. In wild-type mdr2 (+/+) mice, ultrarapid cryofixation of livers in situ revealed abundant unilamellar lipid vesicles within bile canalicular lumina. Although 74% of vesicles were adherent to the external aspect of the canalicular plasma membrane, bilayer exocytosis was not observed. Vesicle numbers in mdr2 (+/-) and (-/-) mice were 55 and 12% of wild-type levels, respectively. In a strain of mdr2 (-/-) mice which had been "rescued" by heterozygous genomic insertion of the MDR3 gene, the human homologue of the murine mdr2 gene, vesicle numbers returned to 95% of wild-type levels. Our findings indicate that biliary phospholipid is secreted as vesicles by a process largely dependent on the action of the murine mdr2 P-glycoprotein or human MDR3 P-glycoprotein. We conclude that mdr2-mediated phospholipid translocation from the internal to external hemileaflet of the canalicular membrane permits exovesiculation of the external hemileaflet, a vesiculation process promoted by the detergent environment of the bile canalicular lumen.
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Affiliation(s)
- A R Crawford
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
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25
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He C, Fischer S, Meyer G, Müller I, Jüngst D. Two-dimensional electrophoretic analysis of vesicular and micellar proteins of gallbladder bile. J Chromatogr A 1997; 776:109-15. [PMID: 9286084 DOI: 10.1016/s0021-9673(97)00560-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Proteins associated with lipid vesicles or mixed micelles of human gallbladder bile were separated by Sepharose-2B gel filtration chromatography followed by protein concentration and delipidation. After two-dimensional polyacrylamide gel electrophoresis and silver staining up to 59 and 471 polypeptide spots were counted in vesicular and micellar fractions, respectively. As major components the plasma proteins transferrin, albumin, alpha-fibrinogen, beta-fibrinogen, gamma-immunoglobulin G, immunoglobulin light chains, alpha-1 antitrypsin and haptoglobin alpha-2 chain were identified in the lipid vesicles by comparison with human protein reference maps. However, most biliary proteins including the anionic polypeptide fraction are associated with mixed micelles. The pathophysiological significance of these proteins associated with lipids needs to be investigated further.
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Affiliation(s)
- C He
- Department of Medicine II, Klinikum Grosshadern, Ludwig-Maximilians University Munich, Germany
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