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Bertolini A, Bloks VW, Wilmink M, Bos E, van de Peppel IP, Eilers R, Prins S, Thomas R, de Bruin A, Verkade H, Jonker JW. Treatment of intestinal and liver features in cystic fibrosis mice by the osmotic laxative polyethylene glycol. J Cyst Fibros 2024; 23:461-473. [PMID: 37775443 DOI: 10.1016/j.jcf.2023.09.015] [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: 05/22/2023] [Revised: 09/07/2023] [Accepted: 09/24/2023] [Indexed: 10/01/2023]
Abstract
BACKGROUND Cystic Fibrosis (CF) is a genetic disease affecting multiple organs, primarily the lungs and digestive system. Improved pulmonary management significantly improved life expectancy of CF patients. As a result, extrapulmonary manifestations, including gastrointestinal and liver-related symptoms, have become more relevant. We previously reported that the osmotic laxative polyethylene glycol (PEG), which hydrates the CF gut, decreased fecal bile acid loss in a CF knockout mouse model. In the current study we investigated the effect of PEG on intestinal fat and cholesterol absorption and on CF-related liver features in a CF mouse model with the most common CF-causing mutation. METHODS CftrΔF508/ΔF508 (n=13) and wild-type (WT) (n=12) mice were treated with PEG for 2 weeks. The intestinal and hepatic effects of PEG were assessed by analysis of intestinal bile acid, cholesterol, and fat fluxes, transcriptome analysis as well as histology. RESULTS PEG improved intestinal malabsorption of bile acids, fat, and cholesterol in CftrΔF508/ΔF508 mice. Transcriptome analysis showed that PEG partially restored the intestinal signaling of nuclear receptors RXR, FXR, and CAR/PXR, which are involved in bile acid and xenobiotic metabolism. PEG also reduced liver inflammation in CF mice as assessed by transcriptome and histological analyses. CONCLUSIONS PEG, a non-absorbable osmotic laxative, improved intestinal nutrient absorption, intestinal bile acid and xenobiotic signaling, as well as CF-related liver features. These findings highlight the potential for osmotic laxation to improve gastrointestinal complications of CF in humans.
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Affiliation(s)
- Anna Bertolini
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Vincent W Bloks
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Marijn Wilmink
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Eline Bos
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Ivo P van de Peppel
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Roos Eilers
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Sake Prins
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Rachel Thomas
- Dutch Molecular Pathology Centre, Department of Pathobiology, Utrecht University, Utrecht, the Netherlands
| | - Alain de Bruin
- Dutch Molecular Pathology Centre, Department of Pathobiology, Utrecht University, Utrecht, the Netherlands
| | - Henkjan Verkade
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Johan W Jonker
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands.
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Angyal D, Kleinfelder K, Ciciriello F, Groeneweg TA, De Marchi G, de Pretis N, Bernardoni L, Rodella L, Tomba F, De Angelis P, Surace C, Pintani E, Alghisi F, de Jonge HR, Melotti P, Sorio C, Lucidi V, Bijvelds MJC, Frulloni L. CFTR function is impaired in a subset of patients with pancreatitis carrying rare CFTR variants. Pancreatology 2024; 24:394-403. [PMID: 38493004 DOI: 10.1016/j.pan.2024.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 03/07/2024] [Accepted: 03/08/2024] [Indexed: 03/18/2024]
Abstract
BACKGROUND Many affected by pancreatitis harbor rare variants of the cystic fibrosis (CF) gene, CFTR, which encodes an epithelial chloride/bicarbonate channel. We investigated CFTR function and the effect of CFTR modulator drugs in pancreatitis patients carrying CFTR variants. METHODS Next-generation sequencing was performed to identify CFTR variants. Sweat tests and nasal potential difference (NPD) assays were performed to assess CFTR function in vivo. Intestinal current measurement (ICM) was performed on rectal biopsies. Patient-derived intestinal epithelial monolayers were used to evaluate chloride and bicarbonate transport and the effects of a CFTR modulator combination: elexacaftor, tezacaftor and ivacaftor (ETI). RESULTS Of 32 pancreatitis patients carrying CFTR variants, three had CF-causing mutations on both alleles and yielded CF-typical sweat test, NPD and ICM results. Fourteen subjects showed a more modest elevation in sweat chloride levels, including three that were provisionally diagnosed with CF. ICM indicated impaired CFTR function in nine out of 17 non-CF subjects tested. This group of nine included five carrying a wild type CFTR allele. In epithelial monolayers, a reduction in CFTR-dependent chloride transport was found in six out of 14 subjects tested, whereas bicarbonate secretion was reduced in only one individual. In epithelial monolayers of four of these six subjects, ETI improved CFTR function. CONCLUSIONS CFTR function is impaired in a subset of pancreatitis patients carrying CFTR variants. Mutations outside the CFTR locus may contribute to the anion transport defect. Bioassays on patient-derived intestinal tissue and organoids can be used to detect such defects and to assess the effect of CFTR modulators.
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Affiliation(s)
- Dora Angyal
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, P.O. Box 2040, 3000, CA, Rotterdam, the Netherlands
| | - Karina Kleinfelder
- Department of Medicine, University of Verona, Division of General Pathology, Verona, Italy
| | - Fabiana Ciciriello
- Cystic Fibrosis Unit, Bambino Gesù Children's Hospital, IRCCS, Piazza di Sant'Onofrio 4, 00165, Rome, Italy
| | - Tessa A Groeneweg
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, P.O. Box 2040, 3000, CA, Rotterdam, the Netherlands
| | - Giulia De Marchi
- Gastroenterology Unit, Department of Medicine, Borgo Roma Hospital, Piazzale L.A. Scuro 10, 37134, Verona, Italy
| | - Nicolò de Pretis
- Gastroenterology Unit, Department of Medicine, Borgo Roma Hospital, Piazzale L.A. Scuro 10, 37134, Verona, Italy
| | - Laura Bernardoni
- Gastroenterology Unit, Department of Medicine, Borgo Roma Hospital, Piazzale L.A. Scuro 10, 37134, Verona, Italy
| | - Luca Rodella
- Endoscopy Surgery Unit, Azienda Ospedaliera Universitaria Integrata Verona, 37126, Verona, Italy
| | - Francesco Tomba
- Endoscopy Surgery Unit, Azienda Ospedaliera Universitaria Integrata Verona, 37126, Verona, Italy
| | - Paola De Angelis
- Digestive Endoscopy and Surgery Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Cecilia Surace
- Laboratory of Medical Genetics, Bambino Gesù Children's Hospital, IRCCS, Viale di San Paolo 15, 00146, Rome, Italy
| | - Emily Pintani
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, Verona, Italy
| | - Federico Alghisi
- Cystic Fibrosis Unit, Bambino Gesù Children's Hospital, IRCCS, Piazza di Sant'Onofrio 4, 00165, Rome, Italy
| | - Hugo R de Jonge
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, P.O. Box 2040, 3000, CA, Rotterdam, the Netherlands
| | - Paola Melotti
- Cystic Fibrosis Centre, Azienda Ospedaliera Universitaria Integrata Verona, Verona, Italy
| | - Claudio Sorio
- Department of Medicine, University of Verona, Division of General Pathology, Verona, Italy
| | - Vincenzina Lucidi
- Cystic Fibrosis Unit, Bambino Gesù Children's Hospital, IRCCS, Piazza di Sant'Onofrio 4, 00165, Rome, Italy
| | - Marcel J C Bijvelds
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, P.O. Box 2040, 3000, CA, Rotterdam, the Netherlands.
| | - Luca Frulloni
- Gastroenterology Unit, Department of Medicine, Borgo Roma Hospital, Piazzale L.A. Scuro 10, 37134, Verona, Italy
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3
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Becker HM, Seidler UE. Bicarbonate secretion and acid/base sensing by the intestine. Pflugers Arch 2024; 476:593-610. [PMID: 38374228 PMCID: PMC11006743 DOI: 10.1007/s00424-024-02914-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 01/15/2024] [Accepted: 01/17/2024] [Indexed: 02/21/2024]
Abstract
The transport of bicarbonate across the enterocyte cell membrane regulates the intracellular as well as the luminal pH and is an essential part of directional fluid movement in the gut. Since the first description of "active" transport of HCO3- ions against a concentration gradient in the 1970s, the fundamental role of HCO3- transport for multiple intestinal functions has been recognized. The ion transport proteins have been identified and molecularly characterized, and knockout mouse models have given insight into their individual role in a variety of functions. This review describes the progress made in the last decade regarding novel techniques and new findings in the molecular regulation of intestinal HCO3- transport in the different segments of the gut. We discuss human diseases with defects in intestinal HCO3- secretion and potential treatment strategies to increase luminal alkalinity. In the last part of the review, the cellular and organismal mechanisms for acid/base sensing in the intestinal tract are highlighted.
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Affiliation(s)
- Holger M Becker
- Department of Gastroenterology, Hannover Medical School, 30625, Hannover, Germany
| | - Ursula E Seidler
- Department of Gastroenterology, Hannover Medical School, 30625, Hannover, Germany.
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4
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Ousingsawat J, Centeio R, Reyne N, McCarron A, Cmielewski P, Schreiber R, diStefano G, Römermann D, Seidler U, Donnelley M, Kunzelmann K. Inhibition of mucus secretion by niclosamide and benzbromarone in airways and intestine. Sci Rep 2024; 14:1464. [PMID: 38233410 PMCID: PMC10794189 DOI: 10.1038/s41598-024-51397-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 01/04/2024] [Indexed: 01/19/2024] Open
Abstract
The Ca2+ activated Cl- channel TMEM16A (anoctamin 1; ANO1) is expressed in secretory epithelial cells of airways and intestine. Previous studies provided evidence for a role of ANO1 in mucus secretion. In the present study we investigated the effects of the two ANO1-inhibitors niclosamide (Niclo) and benzbromarone (Benz) in vitro and in vivo in mouse models for cystic fibrosis (CF) and asthma. In human CF airway epithelial cells (CFBE), Ca2+ increase and activation of ANO1 by adenosine triphosphate (ATP) or ionomycin was strongly inhibited by 200 nM Niclo and 1 µM Benz. In asthmatic mice airway mucus secretion was inhibited by intratracheal instillation of Niclo or Benz. In homozygous F508del-cftr mice, intestinal mucus secretion and infiltration by CD45-positive cells was inhibited by intraperitoneal injection of Niclo (13 mg/kg/day for 7 days). In homozygous F508del-cftr rats intestinal mucus secretion was inhibited by oral application of Benz (5 mg/kg/day for 60 days). Taken together, well tolerated therapeutic concentrations of niclosamide and benzbromarone corresponding to plasma levels of treated patients, inhibit ANO1 and intracellular Ca2+ signals and may therefore be useful in inhibiting mucus hypersecretion and mucus obstruction in airways and intestine of patients suffering from asthma and CF, respectively.
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Affiliation(s)
- Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, University Street 31, 93053, Regensburg, Germany
| | - Raquel Centeio
- Physiological Institute, University of Regensburg, University Street 31, 93053, Regensburg, Germany
| | - Nicole Reyne
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Alexandra McCarron
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Patricia Cmielewski
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, University Street 31, 93053, Regensburg, Germany
| | - Gabriella diStefano
- Department of Gastroenterology, Hannover Medical School, 30625, Hannover, Germany
| | - Dorothee Römermann
- Department of Gastroenterology, Hannover Medical School, 30625, Hannover, Germany
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, 30625, Hannover, Germany
| | - Martin Donnelley
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, University Street 31, 93053, Regensburg, Germany.
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5
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Salari A, Xiu R, Amiri M, Pallenberg ST, Schreiber R, Dittrich AM, Tümmler B, Kunzelmann K, Seidler U. The Anion Channel TMEM16a/Ano1 Modulates CFTR Activity, but Does Not Function as an Apical Anion Channel in Colonic Epithelium from Cystic Fibrosis Patients and Healthy Individuals. Int J Mol Sci 2023; 24:14214. [PMID: 37762516 PMCID: PMC10531629 DOI: 10.3390/ijms241814214] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/08/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023] Open
Abstract
Studies in human colonic cell lines and murine intestine suggest the presence of a Ca2+-activated anion channel, presumably TMEM16a. Is there a potential for fluid secretion in patients with severe cystic fibrosis transmembrane conductance regulator (CFTR) mutations by activating this alternative pathway? Two-dimensional nondifferentiated colonoid-myofibroblast cocultures resembling transit amplifying/progenitor (TA/PE) cells, as well as differentiated monolayer (DM) cultures resembling near-surface cells, were established from both healthy controls (HLs) and patients with severe functional defects in the CFTR gene (PwCF). F508del mutant and CFTR knockout (null) mice ileal and colonic mucosa was also studied. HL TA/PE monolayers displayed a robust short-circuit current response (ΔIeq) to UTP (100 µM), forskolin (Fsk, 10 µM) and carbachol (CCH, 100 µM), while ΔIeq was much smaller in differentiated monolayers. The selective TMEM16a inhibitor Ani9 (up to 30 µM) did not alter the response to luminal UTP, significantly decreased Fsk-induced ΔIeq, and significantly increased CCH-induced ΔIeq in HL TA/PE colonoid monolayers. The PwCF TA/PE and the PwCF differentiated monolayers displayed negligible agonist-induced ΔIeq, without a significant effect of Ani9. When TMEM16a was localized in intracellular structures, a staining in the apical membrane was not detected. TMEM16a is highly expressed in human colonoid monolayers resembling transit amplifying cells of the colonic cryptal neck zone, from both HL and PwCF. While it may play a role in modulating agonist-induced CFTR-mediated anion currents, it is not localized in the apical membrane, and it has no function as an apical anion channel in cystic fibrosis (CF) and healthy human colonic epithelium.
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Affiliation(s)
- Azam Salari
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany; (A.S.); (R.X.); (M.A.)
| | - Renjie Xiu
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany; (A.S.); (R.X.); (M.A.)
| | - Mahdi Amiri
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany; (A.S.); (R.X.); (M.A.)
| | - Sophia Theres Pallenberg
- Department of Pediatric Pneumonology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany (A.-M.D.)
| | - Rainer Schreiber
- Institute of Physiology, University of Regensburg, 93040 Regensburg, Germany; (R.S.); (K.K.)
| | - Anna-Maria Dittrich
- Department of Pediatric Pneumonology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany (A.-M.D.)
| | - Burkhard Tümmler
- Department of Pediatric Pneumonology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany (A.-M.D.)
| | - Karl Kunzelmann
- Institute of Physiology, University of Regensburg, 93040 Regensburg, Germany; (R.S.); (K.K.)
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany; (A.S.); (R.X.); (M.A.)
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6
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Hegyi P, Seidler U, Kunzelmann K. CFTR-beyond the airways: Recent findings on the role of the CFTR channel in the pancreas, the intestine and the kidneys. J Cyst Fibros 2023; 22 Suppl 1:S17-S22. [PMID: 36621373 DOI: 10.1016/j.jcf.2022.12.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 12/31/2022] [Accepted: 12/31/2022] [Indexed: 01/09/2023]
Abstract
With increased longevity of patients suffering from cystic fibrosis, and widespread lung transplantation facilities, the sequelae of defective CFTR in other organs than the airways come to the fore. This minireview highlights recent scientific progress in the understanding of CFTR function in the pancreas, the intestine and the kidney, and explores potential therapeutic strategies to combat defective CFTR function in these organs.
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Affiliation(s)
- Peter Hegyi
- Institute for Translational Medicine, Medical School, University of Pécs, 7624 Pécs, Hungary; Center for Translational Medicine and Institute of Pancreatic Diseases, Semmelweis University, 1085 Budapest, Hungary; Translational Pancreatology Research Group, Interdisciplinary Centre of Excellence for Research Development and Innovation, University of Szeged, 6725 Szeged, Hungary
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany.
| | - Karl Kunzelmann
- Institute of Physiology, Regensburg University, 93040 Regensburg, Germany
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7
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Tan X, Kini A, Römermann D, Seidler U. The NHE3 Inhibitor Tenapanor Prevents Intestinal Obstructions in CFTR-Deleted Mice. Int J Mol Sci 2022; 23:ijms23179993. [PMID: 36077390 PMCID: PMC9456459 DOI: 10.3390/ijms23179993] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 11/30/2022] Open
Abstract
Mutations in the CFTR chloride channel result in intestinal obstructive episodes in cystic fibrosis (CF) patients and in CF animal models. In this study, we explored the possibility of reducing the frequency of obstructive episodes in cftr−/− mice through the oral application of a gut-selective NHE3 inhibitor tenapanor and searched for the underlying mechanisms involved. Sex- and age-matched cftr+/+ and cftr−/− mice were orally gavaged twice daily with 30 mg kg−1 tenapanor or vehicle for a period of 21 days. Body weight and stool water content was assessed daily and gastrointestinal transit time (GTT) once weekly. The mice were sacrificed when an intestinal obstruction was suspected or after 21 days, and stool and tissues were collected for further analysis. Twenty-one day tenapanor application resulted in a significant increase in stool water content and stool alkalinity and a significant decrease in GTT in cftr+/+ and cftr−/− mice. Tenapanor significantly reduced obstructive episodes to 8% compared to 46% in vehicle-treated cftr−/− mice and prevented mucosal inflammation. A decrease in cryptal hyperproliferation, mucus accumulation, and mucosal mast cell number was also observed in tenapanor- compared to vehicle-treated, unobstructed cftr−/− mice. Overall, oral tenapanor application prevented obstructive episodes in CFTR-deficient mice and was safe in cftr+/+ and cftr−/− mice. These results suggest that tenapanor may be a safe and affordable adjunctive therapy in cystic fibrosis patients to alleviate constipation and prevent recurrent DIOS.
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Affiliation(s)
| | | | | | - Ursula Seidler
- Correspondence: ; Tel.: +49-5115-329-427; Fax: +49-5115-328-428
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8
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Kelly J, Al-Rammahi M, Daly K, Flanagan PK, Urs A, Cohen MC, di Stefano G, Bijvelds MJC, Sheppard DN, de Jonge HR, Seidler UE, Shirazi-Beechey SP. Alterations of mucosa-attached microbiome and epithelial cell numbers in the cystic fibrosis small intestine with implications for intestinal disease. Sci Rep 2022; 12:6593. [PMID: 35449374 PMCID: PMC9023491 DOI: 10.1038/s41598-022-10328-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 04/04/2022] [Indexed: 02/07/2023] Open
Abstract
Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Defective CFTR leads to accumulation of dehydrated viscous mucus within the small intestine, luminal acidification and altered intestinal motility, resulting in blockage. These changes promote gut microbial dysbiosis, adversely influencing the normal proliferation and differentiation of intestinal epithelial cells. Using Illumina 16S rRNA gene sequencing and immunohistochemistry, we assessed changes in mucosa-attached microbiome and epithelial cell profile in the small intestine of CF mice and a CF patient compared to wild-type mice and non-CF humans. We found increased abundance of pro-inflammatory Escherichia and depletion of beneficial secondary bile-acid producing bacteria in the ileal mucosa-attached microbiome of CFTR-null mice. The ileal mucosa in a CF patient was dominated by a non-aeruginosa Pseudomonas species and lacked numerous beneficial anti-inflammatory and short-chain fatty acid-producing bacteria. In the ileum of both CF mice and a CF patient, the number of absorptive enterocytes, Paneth and glucagon-like peptide 1 and 2 secreting L-type enteroendocrine cells were decreased, whereas stem and goblet cell numbers were increased. These changes in mucosa-attached microbiome and epithelial cell profile suggest that microbiota-host interactions may contribute to intestinal CF disease development with implications for therapy.
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Affiliation(s)
- Jennifer Kelly
- Department of Infection Biology and Microbiomes, University of Liverpool, Crown Street, Liverpool, L69 7ZB, UK
| | - Miran Al-Rammahi
- Department of Infection Biology and Microbiomes, University of Liverpool, Crown Street, Liverpool, L69 7ZB, UK.,Department of Physiology, Biochemistry and Pharmacology, College of Veterinary Medicine, University of Al-Qadisiyah, Al Diwaniyah, 58002, Iraq
| | - Kristian Daly
- Department of Infection Biology and Microbiomes, University of Liverpool, Crown Street, Liverpool, L69 7ZB, UK
| | - Paul K Flanagan
- Arrowe Park University Teaching Hospital NHS Trust, Wirral, CH49 5PE, UK.,Gastrointestinal and Liver Services, Aintree University Hospital, Lower Lane, Liverpool, Merseyside, L9 7AL, UK
| | - Arun Urs
- Sheffield Children's Hospital NHS Trust, Western Bank, Sheffield, S10 2TH, UK
| | - Marta C Cohen
- Histopathology Department, Sheffield Children's Hospital NHS Trust, Western Bank, Sheffield, S10 2TH, UK
| | - Gabriella di Stefano
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625, Hannover, Germany
| | - Marcel J C Bijvelds
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - David N Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK
| | - Hugo R de Jonge
- Department of Gastroenterology and Hepatology, Erasmus MC University Medical Center, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - Ursula E Seidler
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625, Hannover, Germany
| | - Soraya P Shirazi-Beechey
- Department of Infection Biology and Microbiomes, University of Liverpool, Crown Street, Liverpool, L69 7ZB, UK.
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Bijvelds MJC, Roos FJM, Meijsen KF, Roest HP, Verstegen MMA, Janssens HM, van der Laan LJW, de Jonge HR. Rescue of chloride and bicarbonate transport by elexacaftor-ivacaftor-tezacaftor in organoid-derived CF intestinal and cholangiocyte monolayers. J Cyst Fibros 2021; 21:537-543. [PMID: 34922851 DOI: 10.1016/j.jcf.2021.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 11/04/2021] [Accepted: 12/07/2021] [Indexed: 12/14/2022]
Abstract
BACKGROUND In cystic fibrosis (CF), loss of CF transmembrane conductance regulator (CFTR)-dependent bicarbonate secretion precipitates the accumulation of viscous mucus in the lumen of respiratory and gastrointestinal epithelial tissues. We investigated whether the combination of elexacaftor (ELX), ivacaftor (IVA) and tezacaftor (TEZ), apart from its well-documented effect on chloride transport, also restores Phe508del-CFTR-mediated bicarbonate transport. METHODS Epithelial monolayers were cultured from intestinal and biliary (cholangiocyte) organoids of homozygous Phe508del-CFTR patients and controls. Transcriptome sequencing was performed, and bicarbonate and chloride transport were assessed in the presence or absence of ELX/IVA/TEZ, using the intestinal current measurement technique. RESULTS ELX/IVA/TEZ markedly enhanced bicarbonate and chloride transport across intestinal epithelium. In biliary epithelium, it failed to enhance CFTR-mediated bicarbonate transport but effectively rescued CFTR-mediated chloride transport, known to be requisite for bicarbonate secretion through the chloride-bicarbonate exchanger AE2 (SLC4A2), which was highly expressed by cholangiocytes. Biliary but not intestinal epithelial cells expressed an alternative anion channel, anoctamin-1/TMEM16A (ANO1), and secreted bicarbonate and chloride upon purinergic receptor stimulation. CONCLUSIONS ELX/IVA/TEZ has the potential to restore both chloride and bicarbonate secretion across CF intestinal and biliary epithelia and may counter luminal hyper-acidification in these tissues.
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Affiliation(s)
- Marcel J C Bijvelds
- Department of Gastroenterology and Hepatology, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000CA Rotterdam, the Netherlands.
| | - Floris J M Roos
- Department of Surgery, Erasmus MC Transplant Institute, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000CA Rotterdam, the Netherlands
| | - Kelly F Meijsen
- Department of Gastroenterology and Hepatology, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000CA Rotterdam, the Netherlands
| | - Henk P Roest
- Department of Surgery, Erasmus MC Transplant Institute, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000CA Rotterdam, the Netherlands
| | - Monique M A Verstegen
- Department of Surgery, Erasmus MC Transplant Institute, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000CA Rotterdam, the Netherlands
| | - Hettie M Janssens
- Department of Pediatrics, Division of Respiratory Medicine and Allergology, Erasmus MC-Sophia Children's Hospital, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000CA Rotterdam, the Netherlands
| | - Luc J W van der Laan
- Department of Surgery, Erasmus MC Transplant Institute, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000CA Rotterdam, the Netherlands
| | - Hugo R de Jonge
- Department of Gastroenterology and Hepatology, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000CA Rotterdam, the Netherlands
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Tan Q, di Stefano G, Tan X, Renjie X, Römermann D, Talbot SR, Seidler UE. Inhibition of Na + /H + exchanger isoform 3 improves gut fluidity and alkalinity in cystic fibrosis transmembrane conductance regulator-deficient and F508del mutant mice. Br J Pharmacol 2021; 178:1018-1036. [PMID: 33179259 DOI: 10.1111/bph.15323] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 11/01/2020] [Accepted: 11/02/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND AND PURPOSE Constipation and intestinal obstructive episodes are major health problems in cystic fibrosis (CF) patients. Three FDA-approved drugs against constipation-prone irritable bowel syndrome were tested for their ability to increase luminal fluidity and alkalinity in cystic fibrosis transmembrane conductance regulator (CFTR) null (cftr-/- ) and F508del mutant (F508delmut/mut ) murine intestine. EXPERIMENTAL APPROACH Guanylate cyclase C agonist linaclotide, PGE1 analogue lubiprostone and intestine-specific NHE3 inhibitor tenapanor were perfused through a ~3 cm jejunal, proximal or mid-distal colonic segment in anaesthetized cftr-/- , F508delmut/mut and WT mice. Net fluid balance was determined gravimetrically and alkaline output by pH-stat back titration. KEY RESULTS Basal jejunal fluid absorptive rates were significantly higher and basal HCO3 - output was significantly lower in cftr-/- and F508delmut/mut compared to WT mice. In cftr-/- and F508delmut/mut mice, all three drugs significantly inhibited the fluid absorptive rate and increased alkaline output in the jejunum and tenapanor and lubiprostone, but not linaclotide, in the colon. After tenapanor pre-incubation, linaclotide elicited a robust fluid secretory response in WT jejunum, while no further change in absorptive rates was observed in cftr-/- and F508delmut/mut jejunum, suggesting that the increase in gut fluidity and alkalinity by linaclotide in CF gut is mediated via NHE3 inhibition. Lubiprostone also inhibited fluid absorption in cftr-/- and F508delmut/mut jejunum via NHE3 inhibition but had a residual NHE3-independent effect. CONCLUSION AND IMPLICATIONS Linaclotide, lubiprostone and tenapanor reduced fluid absorption and increased alkaline output in the CF gut. Their application may ameliorate constipation and reduce obstructive episodes in CF patients.
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Affiliation(s)
- Qinghai Tan
- Department of Gastroenterology, Hannover Medical School, Hanover, Germany
| | | | - Xinjie Tan
- Department of Gastroenterology, Hannover Medical School, Hanover, Germany
| | - Xiu Renjie
- Department of Gastroenterology, Hannover Medical School, Hanover, Germany
| | - Dorothee Römermann
- Department of Gastroenterology, Hannover Medical School, Hanover, Germany
| | - Steven R Talbot
- Institute of Veterinary Research, Hannover Medical School, Hanover, Germany
| | - Ursula E Seidler
- Department of Gastroenterology, Hannover Medical School, Hanover, Germany
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Kini A, Singh AK, Riederer B, Yang I, Tan X, Stefano G, Tan Q, Xiao F, Xia W, Suerbaum S, Seidler U. Slc26a3 deletion alters pH-microclimate, mucin biosynthesis, microbiome composition and increases the TNFα expression in murine colon. Acta Physiol (Oxf) 2020; 230:e13498. [PMID: 32415725 DOI: 10.1111/apha.13498] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 05/07/2020] [Accepted: 05/08/2020] [Indexed: 12/24/2022]
Abstract
AIM SLC26A3 (DRA) mediates the absorption of luminal Cl- in exchange for HCO3 - in the distal intestine. Its expression is lost in congenital chloride diarrhoea (CLD) and strongly decreased in the presence of intestinal inflammation. To characterize the consequences of a loss of Slc26a3 beyond disturbed electrolyte transport, colonic mucus synthesis, surface accumulation and composition, pH microclimate, microbiome composition and development of inflammation was studied in slc26a3-/- mice. METHODS The epithelial surface pH microclimate and the surface mucus accumulation in vivo was assessed by two photon microscopy in exteriorized mid colon of anaesthetized slc26a3-/- and wt littermates. Mucus synthesis, composition and inflammatory markers were studied by qPCR and immunohistochemistry and microbiome composition by 16S rRNA sequencing. RESULTS Colonic pH microclimate was significantly more acidic in slc26a3-/- and to a lesser extent in cftr-/- than in wt mice. Goblet cell thecae per crypt were decreased in slc26a3-/- and increased in cftr-/- colon. Mucus accumulation in vivo was reduced, but much less so than in cftr-/- colon, which is possibly related to the different colonic fluid balance. Slc26a3-/- colonic luminal microbiome displayed strong decrease in diversity. These alterations preceded and maybe causally related to increased mucosal TNFα mRNA expression levels and leucocyte infiltration in the mid-distal colon of slc26a3-/- but not of cftr-/- mice. CONCLUSIONS These findings may explain the strong increase in the susceptibility of slc26a3-/- mice to DSS damage, and offer insight into the mechanisms leading to an increased incidence of intestinal inflammation in CLD patients.
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Affiliation(s)
- Archana Kini
- Department of GastroenterologyHannover Medical School Hannover Germany
| | - Anurag K. Singh
- Department of GastroenterologyHannover Medical School Hannover Germany
- Institute for Physiological Chemistry Martin‐Luther University Halle (Saale) Germany
| | - Brigitte Riederer
- Department of GastroenterologyHannover Medical School Hannover Germany
| | - Ines Yang
- Institute of Medical Microbiology and Hospital EpidemiologyHannover Medical School Hannover Germany
| | - Xinjie Tan
- Department of GastroenterologyHannover Medical School Hannover Germany
| | - Gabriella Stefano
- Department of GastroenterologyHannover Medical School Hannover Germany
| | - Qinghai Tan
- Department of GastroenterologyHannover Medical School Hannover Germany
| | - Fang Xiao
- Department of GastroenterologyHannover Medical School Hannover Germany
- Department of Gastroenterology Tongji HospitalHuazhou University of Technology and Science Wuhan China
| | - Weiliang Xia
- Department of GastroenterologyHannover Medical School Hannover Germany
- Department of Hepatobiliary and Transplantation Surgery First affiliated Hospital Zheijang University Hangzhou China
| | - Sebastian Suerbaum
- Institute of Medical Microbiology and Hospital EpidemiologyHannover Medical School Hannover Germany
- Faculty of Medicine Max von Pettenkofer InstituteLMU Munich Munchen Germany
| | - Ursula Seidler
- Department of GastroenterologyHannover Medical School Hannover Germany
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12
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Shan W, Hu Y, Ding J, Yang X, Lou J, Du Q, Liao Q, Luo L, Xu J, Xie R. Advances in Ca 2+ modulation of gastrointestinal anion secretion and its dysregulation in digestive disorders (Review). Exp Ther Med 2020; 20:8. [PMID: 32934673 PMCID: PMC7471861 DOI: 10.3892/etm.2020.9136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/22/2020] [Indexed: 11/29/2022] Open
Abstract
Intracellular calcium (Ca2+) is a critical cell signaling component in gastrointestinal (GI) physiology. Cytosolic calcium ([Ca2+]cyt), as a secondary messenger, controls GI epithelial fluid and ion transport, mucus and neuropeptide secretion, as well as synaptic transmission and motility. The key roles of Ca2+ signaling in other types of secretory cell (including those in the airways and salivary glands) are well known. However, its action in GI epithelial secretion and the underlying molecular mechanisms have remained to be fully elucidated. The present review focused on the role of [Ca2+]cyt in GI epithelial anion secretion. Ca2+ signaling regulates the activities of ion channels and transporters involved in GI epithelial ion and fluid transport, including Cl- channels, Ca2+-activated K+ channels, cystic fibrosis (CF) transmembrane conductance regulator and anion/HCO3- exchangers. Previous studies by the current researchers have focused on this field over several years, providing solid evidence that Ca2+ signaling has an important role in the regulation of GI epithelial anion secretion and uncovering underlying molecular mechanisms. The present review is largely based on previous studies by the current researchers and provides an overview of the currently known molecular mechanisms of GI epithelial anion secretion with an emphasis on Ca2+-mediated ion secretion and its dysregulation in GI disorders. In addition, previous studies by the current researchers demonstrated that different regulatory mechanisms are in place for GI epithelial HCO3- and Cl- secretion. An increased understanding of the roles of Ca2+ signaling and its targets in GI anion secretion may lead to the development of novel strategies to inhibit GI diseases, including the enhancement of fluid secretion in CF and protection of the GI mucosa in ulcer diseases.
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Affiliation(s)
- Weixi Shan
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Yanxia Hu
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Jianhong Ding
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Xiaoxu Yang
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Jun Lou
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Qian Du
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Qiushi Liao
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Lihong Luo
- Department of Oncology and Geriatrics, Traditional Chinese Medicine Hospital of Chishui City, Guizhou 564700, P.R. China
| | - Jingyu Xu
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Rui Xie
- Department of Gastroenterology, The Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
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Deciphering ion transporters, kinases and PDZ-adaptor molecules that mediate guanylate cyclase C agonist-dependent intestinal fluid loss in vivo. Biochem Pharmacol 2020; 178:114040. [DOI: 10.1016/j.bcp.2020.114040] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 05/13/2020] [Indexed: 01/12/2023]
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14
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Ikpa PT, Meijsen KF, Nieuwenhuijze ND, Dulla K, de Jonge HR, Bijvelds MJ. Transcriptome analysis of the distal small intestine of Cftr null mice. Genomics 2020; 112:1139-1150. [DOI: 10.1016/j.ygeno.2019.06.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 06/18/2019] [Accepted: 06/24/2019] [Indexed: 12/22/2022]
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15
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Impaired Intestinal Farnesoid X Receptor Signaling in Cystic Fibrosis Mice. Cell Mol Gastroenterol Hepatol 2019; 9:47-60. [PMID: 31470114 PMCID: PMC6881665 DOI: 10.1016/j.jcmgh.2019.08.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 08/16/2019] [Accepted: 08/16/2019] [Indexed: 12/20/2022]
Abstract
BACKGROUND & AIMS The bile acid (BA)-activated farnesoid X receptor (FXR) controls hepatic BA synthesis and cell proliferation via the intestinal hormone fibroblast growth factor 19. Because cystic fibrosis (CF) is associated with intestinal dysbiosis, anomalous BA handling, and biliary cirrhosis, we investigated FXR signaling in CF. METHODS Intestinal and hepatic expression of FXR target genes and inflammation markers was assessed in Cftr null mice and controls. Localization of the apical sodium-dependent BA transporter was assessed, and BAs in gastrointestinal tissues were analyzed. The CF microbiota was characterized and FXR signaling was investigated in intestinal tissue and organoids. RESULTS Ileal murine fibroblast growth factor 19 ortholog (Fgf15) expression was strongly reduced in CF mice, compared with controls. Luminal BA levels and localization of apical sodium-dependent BA transporter was not affected, and BAs induced Fgf15 up to normal levels in CF ileum, ex vivo, and CF organoids. CF mice showed a dysbiosis that was associated with a marked up-regulation of genes involved in host-microbe interactions, including those involved in mucin glycosylation, antimicrobial defense, and Toll-like receptor signaling. Antibiotic treatment reversed the up-regulation of inflammatory markers and restored intestinal FXR signaling in CF mice. Conversely, FXR-dependent gene induction in ileal tissue and organoids was repressed by bacterial lipopolysaccharide and proinflammatory cytokines, respectively. Loss of intestinal FXR activity was associated with a markedly blunted hepatic trophic response to oral BA supplementation, and with impaired repression of Cyp7a1, the gene encoding the rate-limiting enzyme in BA synthesis. CONCLUSIONS In CF mice, the gut microbiota represses intestinal FXR activity, and, consequently, FXR-dependent hepatic cell proliferation and feedback control of BA synthesis.
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Seidler U, Nikolovska K. Slc26 Family of Anion Transporters in the Gastrointestinal Tract: Expression, Function, Regulation, and Role in Disease. Compr Physiol 2019; 9:839-872. [DOI: 10.1002/cphy.c180027] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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17
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cAMP Stimulates SLC26A3 Activity in Human Colon by a CFTR-Dependent Mechanism That Does Not Require CFTR Activity. Cell Mol Gastroenterol Hepatol 2019; 7:641-653. [PMID: 30659943 PMCID: PMC6438990 DOI: 10.1016/j.jcmgh.2019.01.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 01/07/2019] [Accepted: 01/07/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS SLC26A3 (DRA) is an electroneutral Cl-/HCO3- exchanger that is present in the apical domain of multiple intestinal segments. An area that has continued to be poorly understood is related to DRA regulation in acute adenosine 3',5'-cyclic monophosphate (cAMP)-related diarrheas, in which DRA appears to be both inhibited as part of NaCl absorption and stimulated to contribute to increased HCO3- secretion. Different cell models expressing DRA have shown that cAMP inhibits, stimulates, or does not affect its activity. METHODS This study re-evaluated cAMP regulation of DRA using new tools, including a successful knockout cell model, a specific DRA inhibitor (DRAinh-A250), specific antibodies, and a transport assay that did not rely on nonspecific inhibitors. The studies compared DRA regulation in colonoids made from normal human colon with regulation in the colon cancer cell line, Caco-2. RESULTS DRA is an apical protein in human proximal colon, differentiated colonoid monolayers, and Caco-2 cells. It is glycosylated and appears as 2 bands. cAMP (forskolin) acutely stimulated DRA activity in human colonoids and Caco-2 cells. In these cells, DRA is the predominant apical Cl-/HCO3- exchanger and is inhibited by DRAinh-A250 with a median inhibitory concentration of 0.5 and 0.2 μmol/L, respectively. However, there was no effect of cAMP in HEK293/DRA cells that lacked a cystic fibrosis transmembrane conductance regulator (CFTR). When CFTR was expressed in HEK293/DRA cells, cAMP also stimulated DRA activity. In all cases, cAMP stimulation of DRA was not inhibited by CFTRinh-172. CONCLUSIONS DRA is acutely stimulated by cAMP by a process that is CFTR-dependent, but appears to be one of multiple regulatory effects of CFTR that does not require CFTR activity.
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18
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Pharmacological Inhibition of the Ubiquitin Ligase RNF5 Rescues F508del-CFTR in Cystic Fibrosis Airway Epithelia. Cell Chem Biol 2018; 25:891-905.e8. [PMID: 29754957 DOI: 10.1016/j.chembiol.2018.04.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 02/22/2018] [Accepted: 04/09/2018] [Indexed: 12/20/2022]
Abstract
In cystic fibrosis (CF), deletion of phenylalanine 508 (F508del) in the CFTR channel is associated with misfolding and premature degradation of the mutant protein. Among the known proteins associated with F508del-CFTR processing, the ubiquitin ligase RNF5/RMA1 is particularly interesting. We previously demonstrated that genetic suppression of RNF5 in vivo leads to an attenuation of intestinal pathological phenotypes in CF mice, validating the relevance of RNF5 as a drug target for CF. Here, we used a computational approach, based on ligand docking and virtual screening, to discover inh-02, a drug-like small molecule that inhibits RNF5. In in vitro experiments, treatment with inh-02 modulated ATG4B and paxillin, both known RNF5 targets. In immortalized and primary bronchial epithelial cells derived from CF patients homozygous for the F508del mutation, long-term incubation with inh-02 caused significant F508del-CFTR rescue. This work validates RNF5 as a drug target for CF, providing evidence to support its druggability.
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19
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Marshall WS, Cozzi RRF, Spieker M. WNK1 and p38-MAPK distribution in ionocytes and accessory cells of euryhaline teleost fish implies ionoregulatory function. Biol Open 2017; 6:956-966. [PMID: 28522431 PMCID: PMC5550910 DOI: 10.1242/bio.024232] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Ionocytes of euryhaline teleost fish secrete NaCl, under regulation by serine and threonine kinases, including with-no-lysine kinase (WNK1) and p38 mitogen-activated protein kinase (MAPK). Mummichogs (Fundulus heteroclitus L.) were acclimated to freshwater (FW), full strength seawater (SW) and hypersaline conditions (2SW). Immunocytochemistry of ionocytes in opercular epithelia of fish acclimated to SW and 2SW revealed that WNK1-anti-pT58 phosphoantibody localized strongly to accessory cells and was present in the cytosol of ionocytes, close to cystic fibrosis transmembrane conductance regulator (CFTR) in the apical membrane and the sodium potassium 2 chloride cotransporter (NKCC) in the basolateral membrane. In FW acclimated fish, WNK1 localized to a sub-apical zone, did not colocalize with apical membrane-located sodium chloride cotransporter (NCC), and typically was present in one cell of paired ionocytes and in some single ionocytes. Forskolin treatment (10 μM, 30 min) increased WNK1 immunofluorescence in SW ionocytes only, while hypertonicity had little effect, compared to controls. Anti-p38-MAPK antibody localized to the cytosolic compartment. The distribution of WNK1 and p38MAPK is consistent with a proximal position in regulatory cascades, rather than directly affecting transporters. The strong staining of accessory cells by WNK1 phosphoantibody infers an osmoregulatory function for WNK. Summary: Fish opercular epithelium ionocytes and accessory cells have WNK family kinases that may regulate paracellular and transcellular ion transport.
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Affiliation(s)
- W S Marshall
- Biology Department, St. Francis Xavier University, 2320 Notre Dame Avenue, Antigonish, Nova Scotia B2G 2W5, Canada
| | - R R F Cozzi
- Biology Department, St. Francis Xavier University, 2320 Notre Dame Avenue, Antigonish, Nova Scotia B2G 2W5, Canada
| | - M Spieker
- Biology Department, St. Francis Xavier University, 2320 Notre Dame Avenue, Antigonish, Nova Scotia B2G 2W5, Canada
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Yu Q, Liu X, Liu Y, Riederer B, Li T, Tian DA, Tuo B, Shull G, Seidler U. Defective small intestinal anion secretion, dipeptide absorption, and intestinal failure in suckling NBCe1-deficient mice. Pflugers Arch 2016; 468:1419-32. [PMID: 27228994 PMCID: PMC4951514 DOI: 10.1007/s00424-016-1836-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 05/05/2016] [Accepted: 05/09/2016] [Indexed: 11/27/2022]
Abstract
The electrogenic Na+HCO3− cotransporter NBCe1 (Slc4a4) is strongly expressed in the basolateral enterocyte membrane in a villous/surface predominant fashion. In order to better understand its physiological function in the intestine, isolated mucosae in miniaturized Ussing chambers and microdissected intestinal villi or crypts loaded with the fluorescent pH-indicator BCECF were studied from the duodenum, jejunum, and colon of 14- to 17-days-old slc4a4-deficient (KO) and WT mice. NBCe1 was active in the basal state in all intestinal segments under study, most likely to compensate for acid loads imposed upon the enterocytes. Upregulation of other basolateral base uptake mechanism occurs, but in a segment-specific fashion. Loss of NBCe1 resulted in severely impaired Cl− and fluid secretory response, but not HCO3− secretory response to agonist stimulation. In addition, NBCe1 was found to be active during transport processes that load the surface enterocytes with acid, such as Slc26a3 (DRA)-mediated luminal Cl−/HCO3− exchange or PEPT1-mediated H+/dipeptide uptake. Possibly because of the high energy demand for hyperventilation in conjunction with the fluid secretory and nutrient absorptive defects and the relative scarcity of compensatory mechanisms, NBCe1-deficient mice developed progressive jejunal failure, worsening of metabolic acidosis, and death in the third week of life. Our data suggest that the electrogenic influx of base via NBCe1 maintains enterocyte anion homeostasis and pHi control. Its loss impairs small intestinal Cl− and fluid secretion as well as the neutralization of acid loads imposed on the enterocytes during nutrient and electrolyte absorption.
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Affiliation(s)
- Qin Yu
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Department of Gastroenterology, Tongji Hospital, Huazhong University of Science & Technology, Wuhan, People's Republic of China
| | - Xuemei Liu
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Department of Gastroenterology, Zunyi Medical College, Zunyi, China
| | - Yongjian Liu
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Brigitte Riederer
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Taolang Li
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Department of Gastrointestinal Surgery, Zunyi Medical College, Zunyi, China
| | - De-An Tian
- Department of Gastroenterology, Tongji Hospital, Huazhong University of Science & Technology, Wuhan, People's Republic of China
| | - Biguang Tuo
- Department of Gastroenterology, Zunyi Medical College, Zunyi, China
| | - Gary Shull
- Department of of Molecular Genetics, University of Cincinnati, Cincinnati, OH, USA
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
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Fezai M, Elvira B, Warsi J, Ben-Attia M, Hosseinzadeh Z, Lang F. Up-Regulation of Intestinal Phosphate Transporter NaPi-IIb (SLC34A2) by the Kinases SPAK and OSR1. Kidney Blood Press Res 2015; 40:555-64. [PMID: 26506223 DOI: 10.1159/000368531] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS SPAK (SPS1-related proline/alanine-rich kinase) and OSR1 (oxidative stress-responsive kinase 1), kinases controlled by WNK (with-no-K[Lys] kinase), are powerful regulators of cellular ion transport and blood pressure. Observations in gene-targeted mice disclosed an impact of SPAK/OSR1 on phosphate metabolism. The present study thus tested whether SPAK and/or OSR1 contributes to the regulation of the intestinal Na(+)-coupled phosphate co-transporter NaPi-IIb (SLC34A2). METHODS cRNA encoding NaPi-IIb was injected into Xenopus laevis oocytes without or with additional injection of cRNA encoding wild-type SPAK, constitutively active (T233E)SPAK, WNK insensitive (T233A)SPAK, catalytically inactive (D212A)SPAK, wild-type OSR1, constitutively active (T185E)OSR1, WNK insensitive (T185A)OSR1 or catalytically inactive (D164A)OSR1. The phosphate (1 mM)-induced inward current (I(Pi)) was taken as measure of phosphate transport. RESULTS I(Pi) was observed in NaPi-IIb expressing oocytes but not in water injected oocytes, and was significantly increased by co-expression of SPAK, (T233E)SPAK, OSR1, (T185E)OSR1 or SPAK+OSR1, but not by co-expression of (T233A)SPAK, (D212A)SPAK, (T185A)OSR1, or (D164A)OSR1. SPAK and OSR1 both increased the maximal transport rate of the carrier. CONCLUSIONS SPAK and OSR1 are powerful stimulators of the intestinal Na+-coupled phosphate co-transporter NaPi-IIb.
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Affiliation(s)
- Myriam Fezai
- Department of Physiology I, University of Tx00FC;bingen, Tx00FC;bingen, Germany
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Genetic Inhibition Of The Ubiquitin Ligase Rnf5 Attenuates Phenotypes Associated To F508del Cystic Fibrosis Mutation. Sci Rep 2015; 5:12138. [PMID: 26183966 PMCID: PMC4505316 DOI: 10.1038/srep12138] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 06/17/2015] [Indexed: 12/28/2022] Open
Abstract
Cystic fibrosis (CF) is caused by mutations in the CFTR chloride channel. Deletion of phenylalanine 508 (F508del), the most frequent CF mutation, impairs CFTR trafficking and gating. F508del-CFTR mistrafficking may be corrected by acting directly on mutant CFTR itself or by modulating expression/activity of CFTR-interacting proteins, that may thus represent potential drug targets. To evaluate possible candidates for F508del-CFTR rescue, we screened a siRNA library targeting known CFTR interactors. Our analysis identified RNF5 as a protein whose inhibition promoted significant F508del-CFTR rescue and displayed an additive effect with the investigational drug VX-809. Significantly, RNF5 loss in F508del-CFTR transgenic animals ameliorated intestinal malabsorption and concomitantly led to an increase in CFTR activity in intestinal epithelial cells. In addition, we found that RNF5 is differentially expressed in human bronchial epithelia from CF vs. control patients. Our results identify RNF5 as a target for therapeutic modalities to antagonize mutant CFTR proteins.
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23
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Maléth J, Balázs A, Pallagi P, Balla Z, Kui B, Katona M, Judák L, Németh I, Kemény LV, Rakonczay Z, Venglovecz V, Földesi I, Pető Z, Somorácz Á, Borka K, Perdomo D, Lukacs GL, Gray MA, Monterisi S, Zaccolo M, Sendler M, Mayerle J, Kühn JP, Lerch MM, Sahin-Tóth M, Hegyi P. Alcohol disrupts levels and function of the cystic fibrosis transmembrane conductance regulator to promote development of pancreatitis. Gastroenterology 2015; 148:427-39.e16. [PMID: 25447846 PMCID: PMC4353632 DOI: 10.1053/j.gastro.2014.11.002] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 10/23/2014] [Accepted: 11/04/2014] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Excessive consumption of ethanol is one of the most common causes of acute and chronic pancreatitis. Alterations to the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) also cause pancreatitis. However, little is known about the role of CFTR in the pathogenesis of alcohol-induced pancreatitis. METHODS We measured CFTR activity based on chloride concentrations in sweat from patients with cystic fibrosis, patients admitted to the emergency department because of excessive alcohol consumption, and healthy volunteers. We measured CFTR levels and localization in pancreatic tissues and in patients with acute or chronic pancreatitis induced by alcohol. We studied the effects of ethanol, fatty acids, and fatty acid ethyl esters on secretion of pancreatic fluid and HCO3(-), levels and function of CFTR, and exchange of Cl(-) for HCO3(-) in pancreatic cell lines as well as in tissues from guinea pigs and CFTR knockout mice after administration of alcohol. RESULTS Chloride concentrations increased in sweat samples from patients who acutely abused alcohol but not in samples from healthy volunteers, indicating that alcohol affects CFTR function. Pancreatic tissues from patients with acute or chronic pancreatitis had lower levels of CFTR than tissues from healthy volunteers. Alcohol and fatty acids inhibited secretion of fluid and HCO3(-), as well as CFTR activity, in pancreatic ductal epithelial cells. These effects were mediated by sustained increases in concentrations of intracellular calcium and adenosine 3',5'-cyclic monophosphate, depletion of adenosine triphosphate, and depolarization of mitochondrial membranes. In pancreatic cell lines and pancreatic tissues of mice and guinea pigs, administration of ethanol reduced expression of CFTR messenger RNA, reduced the stability of CFTR at the cell surface, and disrupted folding of CFTR at the endoplasmic reticulum. CFTR knockout mice given ethanol or fatty acids developed more severe pancreatitis than mice not given ethanol or fatty acids. CONCLUSIONS Based on studies of human, mouse, and guinea pig pancreata, alcohol disrupts expression and localization of the CFTR. This appears to contribute to development of pancreatitis. Strategies to increase CFTR levels or function might be used to treat alcohol-associated pancreatitis.
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Affiliation(s)
- József Maléth
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Anita Balázs
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Petra Pallagi
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Zsolt Balla
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Balázs Kui
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Máté Katona
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Linda Judák
- First Department of Medicine, University of Szeged, Szeged, Hungary,Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - István Németh
- Department of Dermatology and Allergology, University of Szeged, Szeged, Hungary
| | - Lajos V. Kemény
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Zoltán Rakonczay
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Viktória Venglovecz
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Imre Földesi
- Department of Laboratory Medicine, University of Szeged, Szeged, Hungary
| | - Zoltán Pető
- Department of Emergency Medicine, University of Szeged, Szeged, Hungary
| | - Áron Somorácz
- Second Department of Pathology, Semmelweis University, Budapest, Hungary
| | - Katalin Borka
- Second Department of Pathology, Semmelweis University, Budapest, Hungary
| | - Doranda Perdomo
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Gergely L. Lukacs
- Department of Physiology, McGill University, Montreal, Quebec, Canada
| | - Mike A. Gray
- Institute for Cell & Molecular Biosciences, Newcastle University, Newcastle upon Tyne, England
| | - Stefania Monterisi
- Department of Physiology, Anatomy and Genetics, Oxford University, Oxford, England
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, Oxford University, Oxford, England
| | - Matthias Sendler
- Department of Medicine A, University Medicine Greifswald, Greifswald, Germany
| | - Julia Mayerle
- Department of Medicine A, University Medicine Greifswald, Greifswald, Germany
| | - Jens-Peter Kühn
- Institute of Radiology, University Medicine, Ernst Moritz University, Greifswald, Germany
| | - Markus M. Lerch
- Department of Medicine A, University Medicine Greifswald, Greifswald, Germany
| | - Miklós Sahin-Tóth
- Department of Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts
| | - Péter Hegyi
- First Department of Medicine, University of Szeged, Szeged, Hungary; MTA-SZTE Lendület Translational Gastroenterology Research Group, Szeged, Hungary.
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Liu X, Li T, Riederer B, Lenzen H, Ludolph L, Yeruva S, Tuo B, Soleimani M, Seidler U. Loss of Slc26a9 anion transporter alters intestinal electrolyte and HCO3(-) transport and reduces survival in CFTR-deficient mice. Pflugers Arch 2014; 467:1261-75. [PMID: 24965066 PMCID: PMC4434866 DOI: 10.1007/s00424-014-1543-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 05/19/2014] [Accepted: 05/20/2014] [Indexed: 12/16/2022]
Abstract
Slc26a9 is an anion transporter that is strongly expressed in the stomach and lung. Slc26a9 variants were recently found associated with a higher incidence of meconium ileus in cystic fibrosis (CF) infants, raising the question whether Slc26a9 is expressed in the intestine and what its functional role is. Slc26a9 messenger RNA (mRNA) was found highly expressed in the mucosae of the murine and human upper gastrointestinal tract, with an abrupt decrease in expression levels beyond the duodenum. Absence of SLC26a9 expression strongly increased the intestinally related mortality in cystic fibrosis transmembrane conductance regulator (CFTR)-deficient mice. Proximal duodenal JHCO3(-) and fluid secretion were reduced in the absence of Slc26a9 expression. In the proximal duodenum of young Slc26a9 KO mice, the glands and villi/crypts were elongated and proliferation was enhanced. This difference was lost with ageing, as were the alterations in fluid movement, whereas the reduction in JHCO3(-) remained. Laser dissection followed by qPCR suggested Slc26a9 expression to be crypt-predominant in the duodenum. In summary, deletion of Slc26a9 caused bicarbonate secretory and fluid absorptive changes in the proximal duodenal mucosa and increased the postweaning death rates in CFTR-deficient mice. Functional alterations in the duodenum were most prominent at young ages. We assume that the association of meconium ileus and Slc26a9 variants may be related to maldigestion and impaired downstream signaling caused by loss of upper GI tract digestive functions, aggravating the situation of lack of secretion and sticky mucus at the site of obstruction in CF intestine.
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Affiliation(s)
- Xuemei Liu
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
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25
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Xiao F, Yu Q, Li J, Johansson MEV, Singh AK, Xia W, Riederer B, Engelhardt R, Montrose M, Soleimani M, Tian DA, Xu G, Hansson GC, Seidler U. Slc26a3 deficiency is associated with loss of colonic HCO3 (-) secretion, absence of a firm mucus layer and barrier impairment in mice. Acta Physiol (Oxf) 2014; 211:161-75. [PMID: 24373192 DOI: 10.1111/apha.12220] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 11/08/2013] [Accepted: 12/17/2013] [Indexed: 12/11/2022]
Abstract
AIM Downregulated in adenoma (DRA, Slc26a3) is a member of the solute carrier family 26 (SLC26), family of anion transporters, which is mutated in familial chloride-losing diarrhoea (CLD). Besides Cl(-) -rich diarrhoea, CLD patients also have a higher-than-average incidence of intestinal inflammation. In a search for potential explanations for this clinical finding, we investigated colonic electrolyte transport, the mucus layer and susceptibility against dextran sodium sulphate (DSS)-induced colitis in Slc26a3(-/-) mice. METHODS HCO3 (-) secretory (JHCO3 (-) ) and fluid absorptive rates were measured by single-pass perfusion in vivo and in isolated mid-distal colonic mucosa in Ussing chambers in vitro. Colonocyte intracellular pH (pHi ) was assessed fluorometrically, the mucus layer by immunohistochemistry and colitis susceptibility by the addition of DSS to the drinking water. RESULTS HCO3 (-) secretory (JHCO3- ) and fluid absorptive rates were strongly reduced in Slc26a3(-/-) mice compared to wild-type (WT) littermates. Despite an increase in sodium/hydrogen exchanger 3 (NHE3) mRNA and protein expression, and intact acid-activation of NHE3, the high colonocyte pH in Slc26a3(-/-) mice prevented Na(+) /H(+) exchange-mediated fluid absorption in vivo. Mucin 2 (MUC2) immunohistochemistry revealed the absence of a firm mucus layer, implying that alkaline secretion and/or an absorptive flux may be necessary for optimal mucus gel formation. Slc26a3(-/-) mice were highly susceptible to DSS damage. CONCLUSIONS Deletion of DRA results in severely reduced colonic HCO3 (-) secretory rate, a loss of colonic fluid absorption, a lack of a firmly adherent mucus layer and a severely reduced colonic mucosal resistance to DSS damage. These data provide potential pathophysiological explanations for the increased susceptibility of CLD patients to intestinal inflammation.
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Affiliation(s)
- F. Xiao
- Department of Gastroenterology; Hannover Medical School; Hannover Germany
- Department of Gastroenterology; Tongji Hospital; Huazhong University of Science & Technology; Wuhan China
| | - Q. Yu
- Department of Gastroenterology; Hannover Medical School; Hannover Germany
- Department of Gastroenterology; Tongji Hospital; Huazhong University of Science & Technology; Wuhan China
| | - J. Li
- Department of Gastroenterology; Hannover Medical School; Hannover Germany
- Department of Nephrology; Tongji Hospital; Huazhong University of Science & Technology; Wuhan China
| | - M. E. V. Johansson
- Department of Medical Biochemistry; University of Gothenburg; Gothenburg Sweden
| | - A. K. Singh
- Department of Gastroenterology; Hannover Medical School; Hannover Germany
| | - W. Xia
- Department of Gastroenterology; Hannover Medical School; Hannover Germany
- School of Medicine; Key Lab of Combined Multiorgan Transplantation; The First Affiliated Hospital; Zhejiang University; Hangzhou China
| | - B. Riederer
- Department of Gastroenterology; Hannover Medical School; Hannover Germany
| | - R. Engelhardt
- Department of Gastroenterology; Hannover Medical School; Hannover Germany
| | - M. Montrose
- Center on Genetics of Transport and Epithelial Biology; University of Cincinnati; Cincinnati OH USA
| | - M. Soleimani
- Center on Genetics of Transport and Epithelial Biology; University of Cincinnati; Cincinnati OH USA
| | - D. A Tian
- Department of Gastroenterology; Tongji Hospital; Huazhong University of Science & Technology; Wuhan China
| | - G. Xu
- Department of Nephrology; Tongji Hospital; Huazhong University of Science & Technology; Wuhan China
| | - G. C. Hansson
- Department of Medical Biochemistry; University of Gothenburg; Gothenburg Sweden
| | - U. Seidler
- Department of Gastroenterology; Hannover Medical School; Hannover Germany
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Gastrointestinal HCO3- transport and epithelial protection in the gut: new techniques, transport pathways and regulatory pathways. Curr Opin Pharmacol 2013; 13:900-8. [PMID: 24280619 DOI: 10.1016/j.coph.2013.10.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 09/29/2013] [Accepted: 10/01/2013] [Indexed: 02/07/2023]
Abstract
The concept of a protective alkaline gastric and duodenal mucus layer is a century old, yet it is amazing how much new information on HCO3(-) transport pathways has emerged recently, made possible by the extensive utilization of gene-deleted and transgenic mice and novel techniques to study HCO3(-) transport. This review highlights recent findings regarding the importance of HCO3(-) for mucosal protection of duodenum and other gastrointestinal epithelia against luminal acid and other damaging factors. Recently, methods have been developed to visualize HCO3(-) transport in vivo by assessing the surface pH in the mucus layer, as well as the epithelial pH. New information about HCO3(-) transport pathways, and emerging concepts about the intricate regulatory network that governs duodenal HCO3(-) secretion are described, and new perspectives for drug therapy discussed.
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Multicenter intestinal current measurements in rectal biopsies from CF and non-CF subjects to monitor CFTR function. PLoS One 2013; 8:e73905. [PMID: 24040112 PMCID: PMC3769519 DOI: 10.1371/journal.pone.0073905] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 07/23/2013] [Indexed: 11/30/2022] Open
Abstract
Intestinal current measurements (ICM) from rectal biopsies are a sensitive means to detect cystic fibrosis transmembrane conductance regulator (CFTR) function, but have not been optimized for multicenter use. We piloted multicenter standard operating procedures (SOPs) to detect CFTR activity by ICM and examined key questions for use in clinical trials. SOPs for ICM using human rectal biopsies were developed across three centers and used to characterize ion transport from non-CF and CF subjects (two severe CFTR mutations). All data were centrally evaluated by a blinded interpreter. SOPs were then used across four centers to examine the effect of cold storage on CFTR currents and compare CFTR currents in biopsies from one subject studied simultaneously either at two sites (24 hours post-biopsy) or when biopsies were obtained by either forceps or suction. Rectal biopsies from 44 non-CF and 17 CF subjects were analyzed. Mean differences (µA/cm2; 95% confidence intervals) between CF and non-CF were forskolin/IBMX=102.6(128.0 to 81.1), carbachol=96.3(118.7 to 73.9), forskolin/IBMX+carbachol=200.9(243.1 to 158.6), and bumetanide=-44.6 (-33.7 to -55.6) (P<0.005, CF vs non-CF for all parameters). Receiver Operating Characteristic curves indicated that each parameter discriminated CF from non-CF subjects (area under the curve of 0.94-0.98). CFTR dependent currents following 18-24 hours of cold storage for forskolin/IBMX, carbachol, and forskolin/IBMX+carbachol stimulation (n=17 non-CF subjects) were 44%, 47.5%, and 47.3%, respectively of those in fresh biopsies. CFTR-dependent currents from biopsies studied after cold storage at two sites simultaneously demonstrated moderate correlation (n=14 non-CF subjects, Pearson correlation coefficients 0.389, 0.484, and 0.533). Similar CFTR dependent currents were detected from fresh biopsies obtained by either forceps or suction (within-subject comparisons, n=22 biopsies from three non-CF subjects). Multicenter ICM is a feasible CFTR outcome measure that discriminates CF from non-CF ion transport, offers unique advantages over other CFTR bioassays, and warrants further development as a potential CFTR biomarker.
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28
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Singh AK, Liu Y, Riederer B, Engelhardt R, Thakur BK, Soleimani M, Seidler U. Molecular transport machinery involved in orchestrating luminal acid-induced duodenal bicarbonate secretion in vivo. J Physiol 2013; 591:5377-91. [PMID: 24018950 DOI: 10.1113/jphysiol.2013.254854] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The duodenal villus brush border membrane expresses several ion transporters and/or channels, including the solute carrier 26 anion transporters Slc26a3 (DRA) and Slc26a6 (PAT-1), the Na(+)/H(+) exchanger isoform 3 (NHE3), as well as the anion channels cystic fibrosis transmembrane conductance regulator (CFTR) and Slc26a9. Using genetically engineered mouse models lacking Scl26a3, Slc26a6, Slc26a9 or Slc9a3 (NHE3), the study was carried out to assess the role of these transporters in mediating the protective duodenal bicarbonate secretory response (DBS-R) to luminal acid; and to compare it to their role in DBS-R elicited by the adenylyl cyclase agonist forskolin. While basal DBS was reduced in the absence of any of the three Slc26 isoforms, the DBS-R to forskolin was not altered. In contrast, the DBS-R to a 5 min exposure to luminal acid (pH 2.5) was strongly reduced in the absence of Slc26a3 or Slc26a9, but not Slc26a6. CFTR inhibitor [CFTR(Inh)-172] reduced the first phase of the acid-induced DBS-R, while NHE3 inhibition (or knockout) abolished the sustained phase of the DBS-R. Luminal acid exposure resulted in the activation of multiple intracellular signalling pathways, including SPAK, AKT and p38 phosphorylation. It induced a biphasic trafficking of NHE3, first rapidly into the brush border membrane, followed by endocytosis in the later stage. We conclude that the long-lasting DBS-R to luminal acid exposure activates multiple duodenocyte signalling pathways and involves changes in trafficking and/or activity of CFTR, Slc26 isoforms Slc26a3 and Slc26a9, and NHE3.
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Affiliation(s)
- Anurag Kumar Singh
- Prof. Dr. U. Seidler: Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Carl-Neuberg-Straße 1, D-30625 Germany.
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Yang N, Garcia MAS, Quinton PM. Normal mucus formation requires cAMP-dependent HCO3- secretion and Ca2+-mediated mucin exocytosis. J Physiol 2013; 591:4581-93. [PMID: 23818690 DOI: 10.1113/jphysiol.2013.257436] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Evidence from the pathology in cystic fibrosis (CF) and recent results in vitro indicate that HCO3- is required for gel-forming mucins to form the mucus that protects epithelial surfaces. Mucus formation and release is a complex process that begins with an initial intracellular phase of synthesis, packaging and apical granule exocytosis that is followed by an extracellular phase of mucin swelling, transport and discharge into a lumen. Exactly where HCO3- becomes crucial in these processes is unknown, but we observed that in the presence of HCO3-, stimulating dissected segments of native mouse intestine with 5-hydroxytryptamine (5-HT) and prostaglandin E2 (PGE2) induced goblet cell exocytosis followed by normal mucin discharge in wild-type (WT) intestines. CF intestines that inherently lack cystic fibrosis transmembrane conductance regulator (CFTR)-dependent HCO3- secretion also demonstrated apparently normal goblet cell exocytosis, but in contrast, this was not followed by similar mucin discharge. Moreover, we found that even in the presence of HCO3-, when WT intestines were stimulated only with a Ca2+-mediated agonist (carbachol), exocytosis was followed by poor discharge as with CF intestines. However, when the Ca2+-mediated agonist was combined with a cAMP-mediated agonist (isoproterenol (isoprenaline) or vasoactive intestinal peptide) in the presence of HCO3- both normal exocytosis and normal discharge was observed. These results indicate that normal mucus formation requires concurrent activation of a Ca2+-mediated exocytosis of mucin granules and an independent cAMP-mediated, CFTR-dependent, HCO3- secretion that appears to mainly enhance the extracellular phases of mucus excretion.
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Affiliation(s)
- Ning Yang
- N. Yang: Division of Respiratory Medicine, Department of Pediatrics, University of California School of Medicine, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0830, USA.
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30
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Singh AK, Xia W, Riederer B, Juric M, Li J, Zheng W, Cinar A, Xiao F, Bachmann O, Song P, Praetorius J, Aalkjaer C, Seidler U. Essential role of the electroneutral Na+-HCO3- cotransporter NBCn1 in murine duodenal acid-base balance and colonic mucus layer build-up in vivo. J Physiol 2013; 591:2189-204. [PMID: 23401617 DOI: 10.1113/jphysiol.2012.247874] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Duodenal epithelial cells need efficient defence strategies during gastric acidification of the lumen, while colonic mucosa counteracts damage by pathogens by building up a bacteria-free adherent mucus layer. Transport of HCO3(-) is considered crucial for duodenal defence against acid as well as for mucus release and expansion, but the transport pathways involved are incompletely understood. This study investigated the significance of the electroneutral Na(+)-HCO3(-) cotransporter NBCn1 for duodenal defence against acid and colonic mucus release. NBCn1 was localized to the basolateral membrane of duodenal villous enterocytes and of colonic crypt cells, with predominant expression in goblet cells. Duodenal villous enterocyte intracellular pH was studied before and during a luminal acid load by two-photon microscopy in exteriorized, vascularly perfused, indicator (SNARF-1 AM)-loaded duodenum of isoflurane-anaesthetized, systemic acid-base-controlled mice. Acid-induced HCO3(-) secretion was measured in vivo by single-pass perfusion and pH-stat titration. After a luminal acid load, NBCn1-deficient duodenocytes were unable to recover rapidly from intracellular acidification and could not respond adequately with protective HCO3(-) secretion. In the colon, build-up of the mucus layer was delayed, and a decreased thickness of the adherent mucus layer was observed, suggesting that basolateral HCO3(-) uptake is essential for optimal release of mucus. The electroneutral Na(+)-HCO3(-) cotransporter NBCn1 displays a differential cellular distribution in the murine intestine and is essential for HCO3(-)-dependent mucosal protective functions, such as recovery of intracellular pH and HCO3(-) secretion in the duodenum and secretion of mucus in the colon.
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Affiliation(s)
- Anurag Kumar Singh
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
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Wilke M, Bot A, Jorna H, Scholte BJ, de Jonge HR. Rescue of murine F508del CFTR activity in native intestine by low temperature and proteasome inhibitors. PLoS One 2012; 7:e52070. [PMID: 23284872 PMCID: PMC3528711 DOI: 10.1371/journal.pone.0052070] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 11/15/2012] [Indexed: 11/19/2022] Open
Abstract
Most patients with Cystic Fibrosis (CF) carry at least one allele with the F508del mutation, resulting in a CFTR chloride channel protein with a processing, gating and stability defect, but with substantial residual activity when correctly sorted to the apical membranes of epithelial cells. New therapies are therefore aimed at improving the folding and trafficking of F508del CFTR, (CFTR correctors) or at enhancing the open probability of the CFTR chloride channel (CFTR potentiators). Preventing premature breakdown of F508del CFTR is an alternative or additional strategy, which is investigated in this study. We established an ex vivo assay for murine F508del CFTR rescue in native intestinal epithelium that can be used as a pre-clinical test for candidate therapeutics. Overnight incubation of muscle stripped ileum in modified William's E medium at low temperature (26°C), and 4 h or 6 h incubation at 37°C with different proteasome inhibitors (PI: ALLN, MG-132, epoxomicin, PS341/bortezomib) resulted in fifty to hundred percent respectively of the wild type CFTR mediated chloride secretion (forskolin induced short-circuit current). The functional rescue was accompanied by enhanced expression of the murine F508del CFTR protein at the apical surface of intestinal crypts and a gain in the amount of complex-glycosylated CFTR (band C) up to 20% of WT levels. Sustained rescue in the presence of brefeldin A shows the involvement of a post-Golgi compartment in murine F508del CFTR degradation, as was shown earlier for its human counterpart. Our data show that proteasome inhibitors are promising candidate compounds for improving rescue of human F508del CFTR function, in combination with available correctors and potentiators.
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Affiliation(s)
- Martina Wilke
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands.
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