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Ng C, Dellschaft NS, Hoad CL, Marciani L, Ban L, Prayle AP, Barr HL, Jaudszus A, Mainz JG, Spiller RC, Gowland P, Major G, Smyth AR. Postprandial changes in gastrointestinal function and transit in cystic fibrosis assessed by Magnetic Resonance Imaging. J Cyst Fibros 2021; 20:591-597. [PMID: 32561324 DOI: 10.1016/j.jcf.2020.06.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 05/24/2020] [Accepted: 06/02/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND Cystic fibrosis (CF) is a multi-system genetic disorder affecting >72,000 people worldwide. Most CF patients experience gastrointestinal symptoms and can develop complications. However, the mechanisms of CF gut disease are not well understood. We evaluated gut function and transit in CF using magnetic resonance imaging (MRI). We hypothesised oro-caecal transit time (OCTT) is longer in CF; with lower small bowel water content (SBWC). METHODS Twelve CF patients aged 12-40 years and 12 age and sex-matched controls underwent serial MRIs over 1 day with standardised meals. The primary endpoint was OCTT, assessed by the appearance of a food bolus in the caecum. Other measures included corrected SBWC and corrected colonic volume (both area under the curve, AUC), gastric half-emptying time and gastrointestinal symptoms. RESULTS OCTT was longer in CF (CF 330 mins [270, >360] vs. controls 210 mins [173, 315], p = 0.04), with no difference in gastric half-emptying times. Corrected SBWC was higher in CF (CF 62 L.min/m2 [36, 80] vs. controls 34 L.min/m2 [28, 41], p = 0.021); minimal postprandial decrease between T240 and T300 (CF 13 mL/m2 [-13, 57] vs. controls 102 mL/m2 [67, 108], p = 0.002) suggests impaired ileal emptying. Corrected colonic volumes were higher in CF (CF 186 L.min/m2 [167, 206] vs. controls 123 L.min/m2 [89, 146], p = 0.012). There were no differences in gastrointestinal symptoms. CONCLUSIONS MRI provides novel insights into CF pathophysiology. Sub-clinical ileal obstruction may be more prevalent than previously thought. Gastrointestinal MRI shows promise as an investigational tool in CF.
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Affiliation(s)
- Christabella Ng
- Division of Child Health, Obstetrics and Gynaecology, University of Nottingham, UK; NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and University of Nottingham, Nottingham, UK
| | - Neele S Dellschaft
- Sir Peter Mansfield Imaging Centre, University of Nottingham, UK; NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and University of Nottingham, Nottingham, UK
| | - Caroline L Hoad
- Sir Peter Mansfield Imaging Centre, University of Nottingham, UK; NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and University of Nottingham, Nottingham, UK
| | - Luca Marciani
- Sir Peter Mansfield Imaging Centre, University of Nottingham, UK; NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and University of Nottingham, Nottingham, UK
| | - Lu Ban
- NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and University of Nottingham, Nottingham, UK
| | - Andrew P Prayle
- Division of Child Health, Obstetrics and Gynaecology, University of Nottingham, UK; NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and University of Nottingham, Nottingham, UK
| | - Helen L Barr
- NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and University of Nottingham, Nottingham, UK; Wolfson Cystic Fibrosis Unit, Nottingham University Hospitals NHS Trust, UK
| | - Anke Jaudszus
- Jena University Hospital, Cystic Fibrosis Centre, Jena, Germany
| | - Jochen G Mainz
- Jena University Hospital, Cystic Fibrosis Centre, Jena, Germany; Brandenburg Medical School (MHB), University, Kinikum Westbrandenburg, Brandenburg an der Havel, Germany
| | - Robin C Spiller
- NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and University of Nottingham, Nottingham, UK; Nottingham Digestive Diseases Centre, University of Nottingham, UK
| | - Penny Gowland
- Sir Peter Mansfield Imaging Centre, University of Nottingham, UK; NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and University of Nottingham, Nottingham, UK
| | - Giles Major
- NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and University of Nottingham, Nottingham, UK; Nottingham Digestive Diseases Centre, University of Nottingham, UK
| | - Alan R Smyth
- Division of Child Health, Obstetrics and Gynaecology, University of Nottingham, UK; NIHR Nottingham Biomedical Research Centre (BRC), Nottingham University Hospitals NHS Trust and University of Nottingham, Nottingham, UK.
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Xu J, Livraghi-Butrico A, Hou X, Rajagopalan C, Zhang J, Song J, Jiang H, Wei HG, Wang H, Bouhamdan M, Ruan J, Yang D, Qiu Y, Xie Y, Barrett R, McClellan S, Mou H, Wu Q, Chen X, Rogers TD, Wilkinson KJ, Gilmore RC, Esther CR, Zaman K, Liang X, Sobolic M, Hazlett L, Zhang K, Frizzell RA, Gentzsch M, O'Neal WK, Grubb BR, Chen YE, Boucher RC, Sun F. Phenotypes of CF rabbits generated by CRISPR/Cas9-mediated disruption of the CFTR gene. JCI Insight 2021; 6:139813. [PMID: 33232302 PMCID: PMC7821608 DOI: 10.1172/jci.insight.139813] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 11/18/2020] [Indexed: 12/20/2022] Open
Abstract
Existing animal models of cystic fibrosis (CF) have provided key insights into CF pathogenesis but have been limited by short lifespans, absence of key phenotypes, and/or high maintenance costs. Here, we report the CRISPR/Cas9-mediated generation of CF rabbits, a model with a relatively long lifespan and affordable maintenance and care costs. CF rabbits supplemented solely with oral osmotic laxative had a median survival of approximately 40 days and died of gastrointestinal disease, but therapeutic regimens directed toward restoring gastrointestinal transit extended median survival to approximately 80 days. Surrogate markers of exocrine pancreas disorders were found in CF rabbits with declining health. CFTR expression patterns in WT rabbit airways mimicked humans, with widespread distribution in nasal respiratory and olfactory epithelia, as well as proximal and distal lower airways. CF rabbits exhibited human CF–like abnormalities in the bioelectric properties of the nasal and tracheal epithelia. No spontaneous respiratory disease was detected in young CF rabbits. However, abnormal phenotypes were observed in surviving 1-year-old CF rabbits as compared with WT littermates, and these were especially evident in the nasal respiratory and olfactory epithelium. The CF rabbit model may serve as a useful tool for understanding gut and lung CF pathogenesis and for the practical development of CF therapeutics.
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Affiliation(s)
- Jie Xu
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan (UM) Medical Center, Ann Arbor, Michigan, USA
| | | | | | | | - Jifeng Zhang
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan (UM) Medical Center, Ann Arbor, Michigan, USA
| | - Jun Song
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan (UM) Medical Center, Ann Arbor, Michigan, USA
| | | | | | - Hui Wang
- Department of Oncology, Karmanos Cancer Institute
| | | | - Jinxue Ruan
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan (UM) Medical Center, Ann Arbor, Michigan, USA
| | - Dongshan Yang
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan (UM) Medical Center, Ann Arbor, Michigan, USA
| | - Yining Qiu
- Center for Molecular Medicine and Genetics, and
| | - Youming Xie
- Department of Oncology, Karmanos Cancer Institute
| | - Ronald Barrett
- Department of Anatomy and Cell Biology, Wayne State University (WSU) School of Medicine, Detroit, Michigan, USA
| | - Sharon McClellan
- Department of Anatomy and Cell Biology, Wayne State University (WSU) School of Medicine, Detroit, Michigan, USA
| | - Hongmei Mou
- Mucosal Immunology & Biology Research Center, Massachusetts General Hospital, Boston, Massachusetts, USA
| | | | | | - Troy D Rogers
- Marsico Lung Institute, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Kristen J Wilkinson
- Marsico Lung Institute, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Rodney C Gilmore
- Marsico Lung Institute, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Charles R Esther
- Marsico Lung Institute, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Khalequz Zaman
- Department of Pediatrics, Case Western Research University School of Medicine, Cleveland, Ohio, USA
| | - Xiubin Liang
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan (UM) Medical Center, Ann Arbor, Michigan, USA
| | | | - Linda Hazlett
- Department of Anatomy and Cell Biology, Wayne State University (WSU) School of Medicine, Detroit, Michigan, USA
| | | | - Raymond A Frizzell
- Department of Pediatrics and Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvnia, USA
| | - Martina Gentzsch
- Marsico Lung Institute, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Wanda K O'Neal
- Marsico Lung Institute, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Barbara R Grubb
- Marsico Lung Institute, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Y Eugene Chen
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan (UM) Medical Center, Ann Arbor, Michigan, USA
| | - Richard C Boucher
- Marsico Lung Institute, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
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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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Schlingmann B, Molina SA, Koval M. Claudins: Gatekeepers of lung epithelial function. Semin Cell Dev Biol 2015; 42:47-57. [PMID: 25951797 DOI: 10.1016/j.semcdb.2015.04.009] [Citation(s) in RCA: 125] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 04/24/2015] [Indexed: 12/25/2022]
Abstract
The lung must maintain a proper barrier between airspaces and fluid filled tissues in order to maintain lung fluid balance. Central to maintaining lung fluid balance are epithelial cells which create a barrier to water and solutes. The barrier function of these cells is mainly provided by tight junction proteins known as claudins. Epithelial barrier function varies depending on the different needs within the segments of the respiratory tree. In the lower airways, fluid is required to maintain mucociliary clearance, whereas in the terminal alveolar airspaces a thin layer of surfactant enriched fluid lowers surface tension to prevent airspace collapse and is critical for gas exchange. As the epithelial cells within the segments of the respiratory tree differ, the composition of claudins found in these epithelial cells is also different. Among these differences is claudin-18 which is uniquely expressed by the alveolar epithelial cells. Other claudins, notably claudin-4 and claudin-7, are more ubiquitously expressed throughout the respiratory epithelium. Claudin-5 is expressed by both pulmonary epithelial and endothelial cells. Based on in vitro and in vivo model systems and histologic analysis of lungs from human patients, roles for specific claudins in maintaining barrier function and protecting the lung from the effects of acute injury and disease are being identified. One surprising finding is that claudin-18 and claudin-4 control lung cell phenotype and inflammation beyond simply maintaining a selective paracellular permeability barrier. This suggests claudins have more nuanced roles for the control of airway and alveolar physiology in the healthy and diseased lung.
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Affiliation(s)
- Barbara Schlingmann
- Department of Medicine, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Emory University School of Medicine, Atlanta, GA 30322, United States; Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Samuel A Molina
- Department of Medicine, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Emory University School of Medicine, Atlanta, GA 30322, United States; Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Michael Koval
- Department of Medicine, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Emory University School of Medicine, Atlanta, GA 30322, United States; Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, United States.
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5
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Reddy MM, Stutts MJ. Status of fluid and electrolyte absorption in cystic fibrosis. Cold Spring Harb Perspect Med 2013; 3:a009555. [PMID: 23284077 DOI: 10.1101/cshperspect.a009555] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Salt and fluid absorption is a shared function of many of the body's epithelia, but its use is highly adapted to the varied physiological roles of epithelia-lined organs. These functions vary from control of hydration of outward-facing epithelial surfaces to conservation and regulation of total body volume. In the most general context, salt and fluid absorption is driven by active Na(+) absorption. Cl(-) is absorbed passively through various available paths in response to the electrical driving force that results from active Na(+) absorption. Absorption of salt creates a concentration gradient that causes water to be absorbed passively, provided the epithelium is water permeable. Key differences notwithstanding, the transport elements used for salt and fluid absorption are broadly similar in diverse epithelia, but the regulation of these elements enables salt absorption to be tailored to very different physiological needs. Here we focus on salt absorption by exocrine glands and airway epithelia. In cystic fibrosis, salt and fluid absorption by gland duct epithelia is effectively prevented by the loss of cystic fibrosis transmembrane conductance regulator (CFTR). In airway epithelia, salt and fluid absorption persists, in the absence of CFTR-mediated Cl(-) secretion. The contrast of these tissue-specific changes in CF tissues is illustrative of how salt and fluid absorption is differentially regulated to accomplish tissue-specific physiological objectives.
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Affiliation(s)
- M M Reddy
- Department of Pediatrics, UCSD School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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6
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Hug MJ, Derichs N, Bronsveld I, Clancy JP. Measurement of ion transport function in rectal biopsies. Methods Mol Biol 2011; 741:87-107. [PMID: 21594780 DOI: 10.1007/978-1-61779-117-8_7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Cystic fibrosis (CF) is caused by mutations in the gene encoding for the cystic fibrosis transmembrane conductance regulator (CFTR). CFTR functions as an anion channel and is known to interact with a number of other cellular proteins involved in ion transport. To date more than 1,800 mutations are known, most of which result in various degrees of impaired transport function of the gene product. Due to the high inter-individual variability of disease onset and progression, CF still is a diagnostic challenge. Implemented almost 20 years ago, the measurement of electrolyte transport function of rectal biopsies is a useful ex vivo tool to diagnose CF. In this chapter we will review the different approaches to perform ion transport measurements and try to highlight the advantages and limitations of these techniques.
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Affiliation(s)
- Martin J Hug
- Pharmacy, University Medical Center Freiburg, D-79106, Freiburg, Germany.
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7
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Hardcastle J, Harwood MD, Taylor CJ. Small intestinal glucose absorption in cystic fibrosis: a study in human and transgenic ΔF508 cystic fibrosis mouse tissues. J Pharm Pharmacol 2010; 56:329-38. [PMID: 15025858 DOI: 10.1211/0022357022863] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Abstract
Intestinal transport is disturbed in cystic fibrosis (CF), with both defective Cl− secretion and changes in absorption being reported. We have examined the effects of the disease on Na+-dependent glucose absorption by the small intestine. Active glucose absorption was monitored as changes in short-circuit current (SCC) in intact and stripped intestinal sheets from normal (Swiss) and transgenic CF (Cftrtm 1 Eur and Cftrtm 2 Cam) mice with the ΔF508 mutation, and in jejunal biopsies from children with CF and normal controls. Na+-dependent glucose uptake at the luminal membrane was measured in brush-border membrane vesicles (BBMVs). Intact and stripped sheets of jejunum and midintestine from Swiss mice exhibited a concentration-dependent increase in SCC with glucose. Apparent Km values were similar in the two preparations, but the apparent Vmax was greater in stripped sheets. This difference was not due to a loss of neural activity in stripped sheets as tetrodotoxin did not influence the glucose-induced SCC in intact sheets. Similar results were observed in stripped sheets of jejunum and mid-intestine from wild-type Cftrtm 1 Eur mice, but in tissues from CF mice the apparent Vmax value was reduced significantly. A lower Vmax was also obtained in intact sheets of mid-intestine from CF (Cftrtm 2 Cam) mice. Jejunal biopsies from CF patients however, exhibited an enhanced glucose-dependent rise in SCC. Na+-dependent uptake by BBMVs from CF (Cftrtm 1 Eur) mice was not reduced compared with wild-type and Swiss BBMVs. It was concluded that, in contrast to human intestine, intestinal glucose absorption was reduced in transgenic mouse models of CF with the ΔF508 mutation, but that this could not be detected in an isolated preparation of brush-border membranes. Transgenic mouse models of CF may not accurately reflect all aspects of intestinal dysfunction in the human disease.
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Affiliation(s)
- J Hardcastle
- Department of Biomedical Science, University of Sheffield, Sheffield, UK.
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Wray C, Mao Y, Pan J, Chandrasena A, Piasta F, Frank JA. Claudin-4 augments alveolar epithelial barrier function and is induced in acute lung injury. Am J Physiol Lung Cell Mol Physiol 2009; 297:L219-27. [PMID: 19447895 DOI: 10.1152/ajplung.00043.2009] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Intact alveolar barrier function is associated with better outcomes in acute lung injury patients; however, the regulation of alveolar epithelial paracellular transport during lung injury has not been extensively investigated. This study was undertaken to determine whether changes in tight junction claudin expression affect alveolar epithelial barrier properties and to determine the mechanisms of altered expression. In anesthetized mice exposed to ventilator-induced lung injury, claudin-4 was specifically induced among tight junction structural proteins. Real-time PCR showed an eightfold increase in claudin-4 expression in the lung injury model. To examine the role of this protein in barrier regulation, claudin-4 function was inhibited with small interfering RNA (siRNA) and a blocking peptide derived from the binding domain of Clostridium perfringens enterotoxin (CPE(BD)). Inhibition of claudin-4 decreased transepithelial electrical resistance but did not alter macromolecule permeability in primary rat and human epithelial cells. In mice, CPE(BD) decreased air space fluid clearance >33% and resulted in pulmonary edema during moderate tidal volume ventilation that did not induce edema in control peptide-treated mice. In vitro phorbol ester induced a ninefold increase in claudin-4 expression that was dependent on PKC activation and the JNK MAPK pathway. These data establish that changes in alveolar epithelial claudin expression influence paracellular transport, alveolar fluid clearance rates, and susceptibility to pulmonary edema. We hypothesize that increased claudin-4 expression early in acute lung injury represents a mechanism to limit pulmonary edema and that the regulation of alveolar epithelial claudin expression may be a novel target for acute lung injury therapy.
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Lucas ML. Enterocyte chloride and water secretion into the small intestine after enterotoxin challenge: unifying hypothesis or intellectual dead end? J Physiol Biochem 2008; 64:69-88. [PMID: 18663997 DOI: 10.1007/bf03168236] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Many forms of diarrhoeal disease, particularly so called "secretory" diarrhoeal disease are thought to arise by the active secretion of chloride ion from the enterocytes, creating an osmotic gradient for fluid movement into the small intestinal lumen. This model implies that normally occurring intestinal secretion is catastrophically enhanced by bacterial enterotoxins. This review advocates that neither normal nor abnormal intestinal secretion from the enterocytes occurs and that no competent proof for chloride secretion exists. Prior to 1970, the physiological evidence failed to support the concept of the formation of intestinal juice as a normal intestinal event. The concept was later revived to explain the high rate of fluid entry into the lumen after exposure to cholera toxin. Much evidence has been advanced for the chloride secretion hypothesis, the dominant secretory paradigm after 1974, but is the evidence sufficiently compelling for it to be regarded as proving the chloride secretory model? The evidence falls into four categories and a fifth conjectural argument that proposes that an abnormal chloride ion channel in cystic fibrotic sufferers confers a natural selective advantage by preventing diarrhoeal disease. Secretion is putatively demonstrated by 1) showing that mass transfer of fluid is into the lumen (secretion) and not merely a failure to transport out of the lumen (failed absorption). Support is offered by 2) chloride ion flux measurements in vitro in Ussing chambers and by 3) short-circuit current measurements that are consistent with and purport to show chloride ion movement into the lumen. In addition, 4) pharmacological agents are identified that affect short-circuit current and these are assumed to be anti-secretory, consistent with the biochemical mechanism for secretion, confirmed wherever possible by mouse knock-out models. Finally, the proxy methods used to study water movement such as elevated short-circuit current measurements show these to be absent in cystic fibrotic patients. The enterocyte secretion hypothesis is challenged here on the basis of an examination of the methods used to show secretion, particularly after exposing the small intestine to heat stable enterotoxin (STa) from E. coli. STa is thought to be secretory because fluid entry into the lumen is claimed, enhanced isotopic flux of chloride ion towards the lumen occurs, an increase in short-circuit current is found, preventable by various drugs that are deemed likely to be anti-secretory and also because the short-circuit current changes after STa are not seen in cystic fibrotic patients. Using volume recovery in vivo, STa is found not to be secretory but only anti-absorptive. Hence, other techniques used to show secretion are not fit for that purpose. If STa is identified as secretory and yet no secretion occurs, how reliable is the evidence for other toxins being secretory when these methods are used? This review concludes that chloride ion secretion is unproven. A review of the literature indicates that secretion occurs not because epithelial cells actively pump water but by interdiction of fluid absorption, increased conductivity through tight junctions and an increased hydrostatic driving force through elevated capillary pressure. The exclusive focus on chloride secretion may explain the failure to develop antisecretory drugs over the last three decades.
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Affiliation(s)
- M L Lucas
- Department of Neuroscience & Biomedical Systems, Institute of Biomedical & Life Sciences, University of Glasgow, G12 8QQ Scotland, Great Britain.
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Abstract
Lessons from the sweat gland on cystic fibrosis (CF) began long before modern medicine became a science. In European folklore, the curse that “a child that taste salty when kissed will soon die” (Alonso y de los Ruyzes de Fonteca J. Diez Previlegios para Mugeres Prenadas. Henares, Spain, 1606) has been taken by many as a direct reference to cystic fibrosis [Busch R. Acta Univ Carol Med (Praha) 36: 13–15, 1990]. The high salt concentration in sweat from patients with CF is now accepted as almost pathognomonic with this fatal genetic disease, but the earliest descriptions of cystic fibrosis as a disease entity did not mention sweat or sweat glands (Andersen DH. Am J Dis Child 56: 344–399, 1938; Andersen DH, Hodges RG. Am J Dis Child 72: 62–80, 1946). Nonetheless, defective sweating soon became an inseparable, and major, component of the constellation of symptoms that diagnose “cystic fibrosis” (Davis PB. Am J Respir Crit Care Med 173: 475–482, 2006). The sweat gland has played a foremost role in diagnosing, defining pathophysiology, debunking misconceptions, and increasing our understanding of the effects of the disease on organs, tissues, cells, and molecules. The sweat gland has taught us much.
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Affiliation(s)
- Paul M Quinton
- Biomedical Sciences, University of California, Riverside, USA.
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11
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Gawenis LR, Hut H, Bot AGM, Shull GE, de Jonge HR, Stien X, Miller ML, Clarke LL. Electroneutral sodium absorption and electrogenic anion secretion across murine small intestine are regulated in parallel. Am J Physiol Gastrointest Liver Physiol 2004; 287:G1140-9. [PMID: 15284023 DOI: 10.1152/ajpgi.00177.2004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Electrolyte transport processes of small intestinal epithelia maintain a balance between hydration of the luminal contents and systemic fluid homeostasis. Under basal conditions, electroneutral Na(+) absorption mediated by Na(+)/H(+) exchanger 3 (NHE3) predominates; under stimulated conditions, increased anion secretion mediated by CFTR occurs concurrently with inhibition of Na(+) absorption. Homeostatic adjustments to diseases that chronically affect the activity of one transporter (e.g., cystic fibrosis) may include adaptations in the opposing transport process to prevent enterosystemic fluid imbalance. To test this hypothesis, we measured electrogenic anion secretion (indexed by the short-circuit current) across NHE3-null [NHE3(-)] murine small intestine and electroneutral Na(+) absorption (by radioisotopic flux analysis) across small intestine of mice with gene-targeted disruptions of the anion secretory pathway, i.e., CFTR-null [CFTR(-)] or Na(+)-K(+)-2Cl(-) cotransporter-null [NKCC1(-)]. Protein expression of NHE3 and CFTR in the intestinal epithelia was measured by immunoblotting. In NHE3(-), compared with wild-type small intestine, maximal and bumetanide-sensitive anion secretion following cAMP stimulation was significantly reduced, and there was a corresponding decrease in CFTR protein expression. In CFTR(-) and NKCC1(-) intestine, Na(+) absorption was significantly reduced compared with wild-type. NHE3 protein expression was decreased in the CFTR(-) intestine but was unchanged in the NKCC1(-) intestine, indicating that factors independent of expression also downregulate NHE3 activity. Together, these data support the concept that absorptive and secretory processes determining NaCl and water movement across the intestinal epithelium are regulated in parallel to maintain balance between the systemic fluid volume and hydration of the luminal contents.
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Affiliation(s)
- Lara R Gawenis
- Dalton Cardiovascular Research Center, Department of Biomedical Sciences, University of Missouri-Columbia, Columbia, MO 65211, USA
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Coates SW, Högenauer C, Santa Ana CA, Rosenblatt RL, Emmett M, Fordtran JS. Inhibition of neutral sodium absorption by a prostaglandin analogue in patients with cystic fibrosis. Gastroenterology 2004; 127:65-72. [PMID: 15236173 DOI: 10.1053/j.gastro.2004.03.064] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS In normal intestine, cyclic nucleotides (adenosine 3',5'-cyclic monophosphate [cAMP], guanosine 3',5'-cyclic monophosphate) and Ca(2+) inhibit neutral sodium absorption. In contrast, in the jejunum of a knockout mouse model of cystic fibrosis (CF), agents that elevate intracellular cAMP levels did not inhibit neutral sodium absorption, suggesting that the antiabsorptive effect of cAMP is dependent on the cystic fibrosis transmembrane conductance regulator (CFTR). The aim of the present study was to determine if a prostaglandin E(1) analogue, which causes elevation of intracellular cAMP and Ca(2+) levels, inhibits neutral sodium absorption in patients with CF in vivo. METHODS Electrolyte and water absorption/secretion was measured during steady state perfusion of the jejunum with a balanced electrolyte solution. Patients with CF and healthy subjects were studied under basal conditions and during intraluminal infusion of a prostaglandin E(1) analogue (misoprostol). RESULTS The rate of neutral sodium absorption in the basal state was similar in healthy subjects and patients with CF. Prostaglandin infusion markedly reduced neutral sodium absorption in both healthy subjects and patients with CF. Prostaglandin caused high rates of electrolyte and water secretion in healthy subjects but only trivial rates of secretion in patients with CF. CONCLUSIONS CFTR mutations causing CF in humans do not prevent prostaglandin E(1) inhibition of neutral sodium absorption, even though these mutations produce a severe defect in prostaglandin-stimulated electrolyte secretion. These findings suggest that an intact antiabsorptive response to either cAMP or Ca(2+) may contribute to the relatively low level of intestinal disease in patients with CF.
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Affiliation(s)
- Stephen W Coates
- Department of Internal Medicine, Baylor University Medical Center, Dallas, Texas 75246, USA
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Dray X, Bienvenu T, Desmazes-Dufeu N, Dusser D, Marteau P, Hubert D. Distal intestinal obstruction syndrome in adults with cystic fibrosis. Clin Gastroenterol Hepatol 2004; 2:498-503. [PMID: 15181619 DOI: 10.1016/s1542-3565(04)00169-7] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS With the improved survival of patients with cystic fibrosis (CF), gastrointestinal complications become more evident in adults with this condition. The aims of this study were to determine the prevalence and clinical features of distal intestinal obstruction syndrome (DIOS) and its relationship with the cystic fibrosis transmembrane conductance regulator (CFTR) genotype in an adult CF population. METHODS Cross-sectional study was conducted in an adult CF cohort. RESULTS Among 171 adults with CF (mean age, 28.9 years), 27 patients (15.8%) reported 43 episodes of DIOS. No significant association was found between DIOS and a history of meconium ileus. The first episode of DIOS occurred in adulthood in 21 cases (77.8%). DIOS recurred in 13 patients (48.1%). All patients who developed DIOS had pancreatic insufficiency. Pulmonary function was significantly more altered in patients with DIOS than in the other patients, but pancreatic insufficiency and age might act as confounding factors. DIOS occurred in 21.9% of patients with a severe CFTR genotype and in only 2.4% of patients with a mild CFTR genotype (P < 0.005). CONCLUSIONS DIOS is frequent in adults with CF with a severe CFTR genotype and/or advanced-stage pulmonary disease. The relative contributions of malabsorption and impaired intestinal secretion in the development of DIOS are discussed.
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Affiliation(s)
- Xavier Dray
- Service d'Hépati-gastroentérologie, Hôpital Européen Georges Pompidou, Paris, France
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