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Dorothee Gunzel - One of the best experts on this subject based on the ideXlab platform.
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Paracellular Transport of phosphate along the intestine
American Journal of Physiology-gastrointestinal and Liver Physiology, 2019Co-Authors: Thomas Knopfel, Dorothee Gunzel, Nina Himmerkus, Markus Bleich, Nati Hernando, Carsten A WagnerAbstract:The Paracellular permeability for phosphate is high along the entire axis of the small and large intestine. There is a slight preference for monovalent phosphate. Paracellular phosphate fluxes do n...
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claudins vital partners in transcellular and Paracellular Transport coupling
Pflügers Archiv: European Journal of Physiology, 2017Co-Authors: Dorothee GunzelAbstract:Tight junction (TJ) strands between epithelial or endothelial cells are formed by claudins, a protein family comprising up to 27 members in mammals. Although many more proteins are involved in the formation of TJ complexes, claudins are the only TJ proteins that are able to form TJ-like strands when overexpressed in cells that are normally devoid of TJs (e.g., fibroblasts). Within the Paracellular cleft, the extracellular domains of claudins provide the matrix that seals the Paracellular pathway. However, within this matrix, some claudins act as channels that specifically allow certain ions to cross this barrier. Barrier-forming claudins predominate in epithelia that enclose compartments containing harmful ion concentrations (e.g., H+ in the stomach, K+ in the inner ear endolymph) or high pressures (e.g., in blastocoel or brain ventricle formation during development). Here, even seemingly minor alterations in TJ composition may be detrimental to the organism. In contrast, in many Transporting epithelia, channel-forming claudins are essential for transcellular and Paracellular Transport coupling. Mutation or knockout of channel-forming claudins in these tissues brings both transcellular and Paracellular Transports to a standstill. The present review will present examples to illustrate the importance of single members of the claudin family in general epithelial Transport physiology.
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Paracellular Transport through healthy and cystic fibrosis bronchial epithelial cell lines do we have a proper model
PLOS ONE, 2014Co-Authors: Natalia Molenda, Dorothee Gunzel, Katarina Urbanova, Nelly Weiser, Kristina Kuschevihrog, Hermann SchillersAbstract:It has been reported recently that the cystic fibrosis transmembrane conductance regulator (CFTR) besides transcellular chloride Transport, also controls the Paracellular permeability of bronchial epithelium. The aim of this study was to test whether overexpressing wtCFTR solely regulates Paracellular permeability of cell monolayers. To answer this question we used a CFBE41o– cell line transfected with wtCFTR or mutant F508del-CFTR and compered them with parental line and healthy 16HBE14o– cells. Transepithelial electrical resistance (TER) and Paracellular fluorescein flux were measured under control and CFTR-stimulating conditions. CFTR stimulation significant decreased TER in 16HBE14o– and also in CFBE41o– cells transfected with wtCFTR. In contrast, TER increased upon stimulation in CFBE41o– cells and CFBE41o– cells transfected with F508del-CFTR. Under non-stimulated conditions, all four cell lines had similar Paracellular fluorescein flux. Stimulation increased only the Paracellular permeability of the 16HBE14o– cell monolayers. We observed that 16HBE14o– cells were significantly smaller and showed a different structure of cell-cell contacts than CFBE41o– and its overexpressing clones. Consequently, 16HBE14o– cells have about 80% more cell-cell contacts through which electrical current and solutes can leak. Also tight junction protein composition is different in ‘healthy’ 16HBE14o– cells compared to ‘cystic fibrosis’ CFBE41o– cells. We found that claudin-3 expression was considerably stronger in 16HBE14o– cells than in the three CFBE41o– cell clones and thus independent of the presence of functional CFTR. Together, CFBE41o– cell line transfection with wtCFTR modifies transcellular conductance, but not the Paracellular permeability. We conclude that CFTR overexpression is not sufficient to fully reconstitute Transport in CF bronchial epithelium. Hence, it is not recommended to use those cell lines to study CFTR-dependent epithelial Transport.
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claudins and other tight junction proteins
Comprehensive Physiology, 2012Co-Authors: Dorothee Gunzel, Michael FrommAbstract:Epithelial Transport relies on the proper function and regulation of the tight junction (TJ), other-wise uncontrolled Paracellular leakage of solutes and water would occur. They also act as a fence against mixing of membrane proteins of the apical and basolateral side. The proteins determining Paracellular Transport consist of four transmembrane regions, intracellular N and C terminals, one intracellular and two extracellular loops (ECLs). The ECLs interact laterally and with counterparts of the neighboring cell and by this achieve a general sealing function. Two TJ protein families can be distinguished, claudins, comprising 27 members in mammals, and TJ-associated MARVEL proteins (TAMP), comprising occludin, tricellulin, and MarvelD3. They are linked to a multitude of TJ-associated regulatory and scaffolding proteins. The major TJ proteins are classified according to the physiological role they play in enabling or preventing Paracellular Transport. Many TJ proteins have sealing functions (claudins 1, 3, 5, 11, 14, 19, and tricellulin). In contrast, a significant number of claudins form channels across TJs which feature selectivity for cations (claudins 2, 10b, and 15), anions (claudin-10a and -17), or are permeable to water (claudin-2). For several TJ proteins, function is yet unclear as their effects on epithelial barriers are inconsistent (claudins 4, 7, 8, 16, and occludin). TJs undergo physiological and pathophysiological regulation by altering protein composition or abundance. Major pathophysiological conditions which involve changes in TJ protein composition are (1) effects of pathogens binding to TJ proteins, (2) altered TJ protein composition during inflammation and infection, and (3) altered TJ protein expression in cancers. © 2012 American Physiological Society. Compr Physiol 2:1819-1852, 2012.
Katalin Szaszi - One of the best experts on this subject based on the ideXlab platform.
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tumor necrosis factor α induces claudin 3 upregulation in kidney tubular epithelial cells through nf κb and creb1
American Journal of Physiology-cell Physiology, 2021Co-Authors: Shaista Anwer, Katalin Szaszi, Emily Branchard, Qinghong Dan, Angela DanAbstract:Claudins are essential for tight junction formation and Paracellular Transport, and they affect key cellular events including proliferation and migration. The properties of tight junctions are dyna...
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coupling between apical and Paracellular Transport processes
Biochemistry and Cell Biology, 2006Co-Authors: Andras Kapus, Katalin SzasziAbstract:Transcellular Transport affects the Paracellular flux through 2 distinct mechanisms: by determining the driving force and by altering the permeability of the Paracellular pathway. Such coordination...
Stefan Luschnig - One of the best experts on this subject based on the ideXlab platform.
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transient opening of tricellular vertices controls Paracellular Transport through the follicle epithelium during drosophila oogenesis
Developmental Cell, 2021Co-Authors: Jone Isastisanchez, Fenja Munzzeise, Mylene Lancino, Stefan LuschnigAbstract:Paracellular permeability is regulated to allow solute Transport or cell migration across epithelial or endothelial barriers. However, how cell-cell junction dynamics controls Paracellular permeability is poorly understood. Here, we describe patency, a developmentally regulated process in Drosophila oogenesis, during which cell vertices in the follicular epithelium open transiently to allow Paracellular Transport of yolk proteins for uptake by the oocyte. We show that the sequential removal of E-cadherin, N-cadherin, NCAM/Fasciclin 2, and Sidekick from vertices precedes their basal-to-apical opening, while the subsequent assembly of tricellular occluding junctions marks the termination of patency and seals the Paracellular barrier. E-cadherin-based adhesion is required to limit Paracellular channel size, whereas stabilized adherens junctions, prolonged NCAM/Fasciclin 2 expression, blocked endocytosis, or increased actomyosin contractility prevent patency. Our findings reveal a key role of cell vertices as gateways controlling Paracellular Transport and demonstrate that dynamic regulation of adhesion and actomyosin contractility at vertices governs epithelial barrier properties.
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Transient opening of tricellular vertices controls Paracellular Transport through the follicle epithelium during Drosophila oogenesis
2020Co-Authors: Jone Isasti-sanchez, Fenja Münz-zeise, Stefan LuschnigAbstract:Abstract Paracellular permeability is regulated to allow solute Transport or migration of cells across epithelial or endothelial barriers. However, how occluding junction dynamics controls Paracellular permeability is poorly understood. Here we describe patency, a developmentally regulated process in Drosophila oogenesis, during which cell vertices in the follicle epithelium open transiently to allow Paracellular Transport of yolk proteins for uptake by the oocyte. We show that the sequential removal of E-Cadherin, N-Cadherin, NCAM/Fasciclin-2 and Sidekick from vertices precedes their basal-to-apical opening, while the subsequent assembly of tricellular occluding junctions terminates patency and seals the Paracellular barrier. E-Cadherin-based adhesion is required to limit Paracellular channel size, whereas stabilized adherens junctions, prolonged NCAM/Fasciclin-2 expression, impeded endocytosis, or increased actomyosin contractility prevent patency. Our findings reveal a key role of cell vertices as gateways controlling Paracellular Transport, and demonstrate that the dynamic regulation of adhesion and actomyosin contractility at vertices governs epithelial barrier properties.
H E Junginger - One of the best experts on this subject based on the ideXlab platform.
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chitosan and its derivatives in mucosal drug and vaccine delivery
European Journal of Pharmaceutical Sciences, 2001Co-Authors: Inez M Van Der Lubben, Gerrit Borchard, Coos J Verhoef, H E JungingerAbstract:Numerous studies have demonstrated that chitosan and their derivatives (N-trimethyl chitosan, mono-N-carboxymethyl chitosan) are effective and safe absorption enhancers to improve mucosal (nasal, peroral) delivery of hydrophylic macromolecules such as peptide and protein drugs and heparins. This absorption enhancing effect of chitosans is caused by opening of the intercellular tight junctions, thereby favouring the Paracellular Transport of macromolecular drugs. Chitosan nano- and microparticles are also suitable for controlled drug release. Association of vaccines to some of these particulate systems has shown to enhance the antigen uptake by mucosal lymphoid tissues, thereby inducing strong systemtic and mucosal immune responses against the antigens. The aspecific adjuvant activity of chitosans seems to be dependent on the degree of deacetylation and the type of formulation. From the studies reviewed it is concluded that chitosan and chitosan derivatives are promising polymeric excipients for mucosal drug and vaccine delivery.
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effects of n trimethyl chitosan chloride a novel absorption enhancer on caco 2 intestinal epithelia and the ciliary beat frequency of chicken embryo trachea
International Journal of Pharmaceutics, 1999Co-Authors: Maya Thanou, Coos J Verhoef, Stefan Romeijn, Fred J Nagelkerke, F W H M Merkus, H E JungingerAbstract:N-trimethyl chitosan (TMC) polymers are quaternized chitosans in different degrees of trimethylation. These polymers enhance the absorption of macromolecules through mucosal epithelia by triggering the reversible opening of tight junctions and only allow for Paracellular Transport. To investigate the safety of these novel absorption enhancers cytotoxicity and ciliotoxicity studies have been performed. Intestinal Caco-2 cell monolayers were chosen to study possible membrane damaging effects of these polymers, using confocal laser scanning microscopy visualization of nuclear staining by a membrane impermeable fluorescent probe during Transport of the Paracellular marker Texas red dextran (MW 10 000). Ciliated chicken embryo trachea tissue was used to study the effect of the polymers on the ciliary beat frequency (CBF) in vitro. In both studies the TMC polymers of different degrees of substitution (20, 40 and 60%) were tested at a concentration of 1.0% (w/v). No substantial cell membrane damage could be detected on the Caco-2 cells treated with TMCs, while the effect on the CBF in vitro was found to be marginal. TMC60 and TMC40 enhance Paracellular Transport of Texas red dextran in Caco-2 cell monolayers, whereas TMC20 is ineffective. In conclusion, TMCs of high degrees of substitution may be effective and safe absorption enhancers for peptide and protein drug delivery.
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the potential of mucoadhesive polymers in enhancing intestinal peptide drug absorption iii effects of chitosan glutamate and carbomer on epithelial tight junctions in vitro
Journal of Controlled Release, 1996Co-Authors: Gerrit Borchard, Henrik L Lueβen, Albertus G De Boer, Coos J Verhoef, Claus-michael Lehr, H E JungingerAbstract:Two mucoadhesive polymers, chitosan-glutamate and carbomer, were studied in an in vitro model (Caco-2 cell monolayers) with respect to their ability to enhance intestinal peptide drug delivery. Preparations of the polymers at concentrations of 0.5, 1.0, and 1.5% w/v (chitosan), and of 0.5 and 1.0% w/v (carbomer) were applied to the apical side of Caco-2 cell monolayers. The effects on transepithelial electrical resistance (TEER), Paracellular Transport of a FITC-dextran of a molecular weight of 4400 (FD-4) and [14C]mannitol were measured. Paracellular Transport of FD-4 was visualized by means of confocal laser scanning microscopy (CLSM). Furthermore, the impact of lowering the pH of the polymer solutions to pH 4 on the integrity of the cell layer was determined. The results show that both polymers were able to decrease TEER of Caco-2 cell layers significantly. In the case of carbomer, CLSM revealed a partial opening of epithelial tight junctions. Lowering of the pH in the control and polymer solutions to pH 4 resulted in every case in the irreversible damage of a large percentage of the cells, as shown by CLSM. Transport studies with [14C]mannitol and FD-4 showed only during co-application of carbomer significantly increased fluxes, whereas no difference from the control solution could be detected for chitosan-glutamate. A threshold value of about 50% of TEER reduction has been identified, which allows for Transport of hydrophilic compounds across the cell monolayers of the Caco-2 cell model.
Albertus G De Boer - One of the best experts on this subject based on the ideXlab platform.
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establishment and functional characterization of an in vitro model of the blood brain barrier comprising a co culture of brain capillary endothelial cells and astrocytes
European Journal of Pharmaceutical Sciences, 2001Co-Authors: Pieter J Gaillard, Albertus G De Boer, Levina Helena Voorwinden, Jette Lyngholm Nielsen, Alexei Ivanov, Ryo Atsumi, Helena Engman, Carina Ringbom, Douwe D. BreimerAbstract:Abstract Objective: The aim was to establish a flexible, abundantly available, reproducible and functionally characterized in vitro model of the blood–brain barrier (BBB). Methods: In a first step, bovine brain capillaries and newborn rat astrocytes were isolated. Subsequently, a co-culture of primary brain capillary endothelial cells (BCEC) on semi-permeable filter inserts, with astrocytes on the bottom of the filter was established. The cell material was characterized on the basis of specific cell-type properties and (functional expression of) specific BBB properties. Results: BCEC displayed: (1) characteristic endothelial cell morphology; (2) expression of endothelial cell markers (i.e., CD51, CD62P, CD71 and cadherin 5); (3) marginal F-actin localization; (4) tight junction formation between the cells; (5) expression of γ-glutamyl-transpeptidase (γ-GTP); (6) expression of P-glycoprotein (Pgp); (7) functional transendothelial transferrin Transport and uptake; (8) restriction of Paracellular Transport; and (9) high transendothelial electrical resistance (TEER). Astrocytes displayed characteristic astrocyte morphology and expressed glial fibrillary acidic protein (GFAP). Co-culture with astrocytes increased TEER and decreased Paracellular Transport. In addition, expression of the glucocorticoid receptor (GR) was demonstrated in the endothelial cells of the BBB, while no expression of the mineralocorticoid receptor (MR) was found. Conclusions: A high quality and mass-production in vitro BBB model was established in which experiments with physiological (e.g., regulation of BBB permeability), pharmacological (e.g., pharmacokinetics and pharmacodynamics) and pathophysiological (e.g., disease influence on BBB permeability) objectives can be reproducibly performed.
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the potential of mucoadhesive polymers in enhancing intestinal peptide drug absorption iii effects of chitosan glutamate and carbomer on epithelial tight junctions in vitro
Journal of Controlled Release, 1996Co-Authors: Gerrit Borchard, Henrik L Lueβen, Albertus G De Boer, Coos J Verhoef, Claus-michael Lehr, Hans E. JungingerAbstract:Two mucoadhesive polymers, chitosan-glutamate and carbomer, were studied in an in vitro model (Caco-2 cell monolayers) with respect to their ability to enhance intestinal peptide drug delivery. Preparations of the polymers at concentrations of 0.5, 1.0, and 1.5% w/v (chitosan), and of 0.5 and 1.0% w/v (carbomer) were applied to the apical side of Caco-2 cell monolayers. The effects on transepithelial electrical resistance (TEER), Paracellular Transport of a FITC-dextran of a molecular weight of 4400 (FD-4) and [14C]mannitol were measured. Paracellular Transport of FD-4 was visualized by means of confocal laser scanning microscopy (CLSM). Furthermore, the impact of lowering the pH of the polymer solutions to pH 4 on the integrity of the cell layer was determined. The results show that both polymers were able to decrease TEER of Caco-2 cell layers significantly. In the case of carbomer, CLSM revealed a partial opening of epithelial tight junctions. Lowering of the pH in the control and polymer solutions to pH 4 resulted in every case in the irreversible damage of a large percentage of the cells, as shown by CLSM. Transport studies with [14C]mannitol and FD-4 showed only during co-application of carbomer significantly increased fluxes, whereas no difference from the control solution could be detected for chitosan-glutamate. A threshold value of about 50% of TEER reduction has been identified, which allows for Transport of hydrophilic compounds across the cell monolayers of the Caco-2 cell model.
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the potential of mucoadhesive polymers in enhancing intestinal peptide drug absorption iii effects of chitosan glutamate and carbomer on epithelial tight junctions in vitro
Journal of Controlled Release, 1996Co-Authors: Gerrit Borchard, Henrik L Lueβen, Albertus G De Boer, Coos J Verhoef, Claus-michael Lehr, H E JungingerAbstract:Two mucoadhesive polymers, chitosan-glutamate and carbomer, were studied in an in vitro model (Caco-2 cell monolayers) with respect to their ability to enhance intestinal peptide drug delivery. Preparations of the polymers at concentrations of 0.5, 1.0, and 1.5% w/v (chitosan), and of 0.5 and 1.0% w/v (carbomer) were applied to the apical side of Caco-2 cell monolayers. The effects on transepithelial electrical resistance (TEER), Paracellular Transport of a FITC-dextran of a molecular weight of 4400 (FD-4) and [14C]mannitol were measured. Paracellular Transport of FD-4 was visualized by means of confocal laser scanning microscopy (CLSM). Furthermore, the impact of lowering the pH of the polymer solutions to pH 4 on the integrity of the cell layer was determined. The results show that both polymers were able to decrease TEER of Caco-2 cell layers significantly. In the case of carbomer, CLSM revealed a partial opening of epithelial tight junctions. Lowering of the pH in the control and polymer solutions to pH 4 resulted in every case in the irreversible damage of a large percentage of the cells, as shown by CLSM. Transport studies with [14C]mannitol and FD-4 showed only during co-application of carbomer significantly increased fluxes, whereas no difference from the control solution could be detected for chitosan-glutamate. A threshold value of about 50% of TEER reduction has been identified, which allows for Transport of hydrophilic compounds across the cell monolayers of the Caco-2 cell model.
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in vitro penetration of des tyrosine1 d phenylalanine3 β casomorphin across the blood brain barrier
Peptides, 1992Co-Authors: Joost B M M Van Bree, Ulrich Jaehde, Albertus G De Boer, Douwe D. BreimerAbstract:Abstract The blood-brain barrier Transport and metabolism of the synthetic β-casomorphin (βCM) derivative des-tyrosine 1 -D-phenylalanine 3 -β-casomorphin (DT-D-Phe 3 -βCM) were investigated using an in vitro model consisting of primary cultures of bovine cerebrovascular endothelial cells. DT-D-Phe 3 -βCM was Transported across the endothelial monolayer without significant metabolism. The endothelial permeability expressing the Transport rate ranged between 1.4 and 2.2 cm × 10 −3 / min and was neither affected by luminal concentration changes (1 nM and 1 μM) nor different after luminal and abluminal administration. The metabolic inhibitor 2-desoxy-D-glucose did not affect the permeability of DT-D-Phe 3 -βCM. These results suggest that DT-D-Phe 3 -βCM is able to cross the blood-brain barrier by Paracellular Transport without using a carrier system.
