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Saikumar P, Sadauskas M, Izhar S, Moshiree B, Patel D. Constipation and DIOS: Diagnosis, differential diagnosis, and management. Pediatr Pulmonol 2024; 59 Suppl 1:S81-S90. [PMID: 39105354 DOI: 10.1002/ppul.27104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 04/22/2024] [Accepted: 05/22/2024] [Indexed: 08/07/2024]
Abstract
Cystic Fibrosis (CF) is a complex disorder that requires multidisciplinary expertise for effective management. The GALAXY study estimated the prevalence of constipation to be about 25% among People with Cystic Fibrosis (PwCF), identifying it as one of the common gastrointestinal (GI) symptoms within this patient population. Quality of Life (QoL) assessments uncovered high patient dissatisfaction, highlighting the imperative need for enhanced treatment strategies. Similarly, Distal Intestinal Obstruction Syndrome (DIOS) is a unique condition exclusive to PwCF that, if left undiagnosed, can lead to considerable morbidity and mortality. Given the broad spectrum of differential diagnoses for abdominal pain, including constipation and DIOS, it is paramount for healthcare providers to possess a clear understanding of these conditions. This paper aims to delineate various differentials for abdominal pain while elucidating the pathogenesis, diagnostic criteria, and treatment options for managing constipation and DIOS in PwCF.
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Affiliation(s)
- Pavithra Saikumar
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology and Nutrition, Cardinal Glennon Children's Medical Center, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Marisa Sadauskas
- Department of Pediatrics, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Sophia Izhar
- Department of Pediatrics, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Baha Moshiree
- Atrium Health, Division of Gastroenterology, Hepatology and Nutrition, Wake Forest Medical University, Charlotte, North Carolina, USA
| | - Dhiren Patel
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology and Nutrition, Cardinal Glennon Children's Medical Center, Saint Louis University School of Medicine, St. Louis, Missouri, USA
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2
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Sarthi JB, Trumbull AM, Abazari SM, van Unen V, Chan JE, Jiang Y, Gammons J, Anderson MO, Cil O, Kuo CJ, Sellers ZM. DRA involvement in linaclotide-stimulated bicarbonate secretion during loss of CFTR function. JCI Insight 2024; 9:e172364. [PMID: 38869953 DOI: 10.1172/jci.insight.172364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 06/11/2024] [Indexed: 06/15/2024] Open
Abstract
Duodenal bicarbonate secretion is critical to epithelial protection, as well as nutrient digestion and absorption, and is impaired in cystic fibrosis (CF). We examined if linaclotide, typically used to treat constipation, may also stimulate duodenal bicarbonate secretion. Bicarbonate secretion was measured in vivo and in vitro using mouse and human duodenum (biopsies and enteroids). Ion transporter localization was identified with confocal microscopy, and de novo analysis of human duodenal single-cell RNA sequencing (scRNA-Seq) data sets was performed. Linaclotide increased bicarbonate secretion in mouse and human duodenum in the absence of cystic fibrosis transmembrane conductance regulator (CFTR) expression (Cftr-knockout mice) or function (CFTRinh-172). Na+/H+ exchanger 3 inhibition contributed to a portion of this response. Linaclotide-stimulated bicarbonate secretion was eliminated by down-regulated in adenoma (DRA, SLC26A3) inhibition during loss of CFTR activity. ScRNA-Seq identified that 70% of villus cells expressed SLC26A3, but not CFTR, mRNA. Loss of CFTR activity and linaclotide increased apical brush border expression of DRA in non-CF and CF differentiated enteroids. These data provide further insights into the action of linaclotide and how DRA may compensate for loss of CFTR in regulating luminal pH. Linaclotide may be a useful therapy for CF individuals with impaired bicarbonate secretion.
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Affiliation(s)
- Jessica B Sarthi
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition; and
| | - Annie M Trumbull
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition; and
| | - Shayda M Abazari
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition; and
| | - Vincent van Unen
- Department of Medicine, Division of Hematology, Stanford University, Palo Alto, California, USA
| | - Joshua E Chan
- Department of Medicine, Division of Hematology, Stanford University, Palo Alto, California, USA
| | - Yanfen Jiang
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition; and
| | - Jesse Gammons
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition; and
| | - Marc O Anderson
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, California, USA
| | - Onur Cil
- Department of Pediatrics, University of California, San Francisco, San Francisco, California, USA
| | - Calvin J Kuo
- Department of Medicine, Division of Hematology, Stanford University, Palo Alto, California, USA
| | - Zachary M Sellers
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition; and
- Sellers Research and Clinical Development, LLC, Newark, California, USA
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3
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Roussa E, Juda P, Laue M, Mai-Kolerus O, Meyerhof W, Sjöblom M, Nikolovska K, Seidler U, Kilimann MW. LRBA, a BEACH protein mutated in human immune deficiency, is widely expressed in epithelia, exocrine and endocrine glands, and neurons. Sci Rep 2024; 14:10678. [PMID: 38724551 PMCID: PMC11082223 DOI: 10.1038/s41598-024-60257-6] [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: 01/29/2024] [Accepted: 04/20/2024] [Indexed: 05/12/2024] Open
Abstract
Mutations in LRBA, a BEACH domain protein, cause severe immune deficiency in humans. LRBA is expressed in many tissues and organs according to biochemical analysis, but little is known about its cellular and subcellular localization, and its deficiency phenotype outside the immune system. By LacZ histochemistry of Lrba gene-trap mice, we performed a comprehensive survey of LRBA expression in numerous tissues, detecting it in many if not all epithelia, in exocrine and endocrine cells, and in subpopulations of neurons. Immunofluorescence microscopy of the exocrine and endocrine pancreas, salivary glands, and intestinal segments, confirmed these patterns of cellular expression and provided information on the subcellular localizations of the LRBA protein. Immuno-electron microscopy demonstrated that in neurons and endocrine cells, which co-express LRBA and its closest relative, neurobeachin, both proteins display partial association with endomembranes in complementary, rather than overlapping, subcellular distributions. Prominent manifestations of human LRBA deficiency, such as inflammatory bowel disease or endocrinopathies, are believed to be primarily due to immune dysregulation. However, as essentially all affected tissues also express LRBA, it is possible that LRBA deficiency enhances their vulnerability and contributes to the pathogenesis.
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Affiliation(s)
- Eleni Roussa
- Department Molecular Embryology, Institute of Anatomy and Cell Biology, Faculty of Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Pavel Juda
- Department of Molecular Neurobiology, Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany
- Leukocyte Motility Lab, 1st Faculty of Medicine, Charles University of Prague, Vestec, Czech Republic
| | - Michael Laue
- Advanced Light and Electron Microscopy (ZBS 4), Robert Koch Institute, Berlin, Germany
| | - Oliver Mai-Kolerus
- Department of Molecular Genetics, German Institute for Human Nutrition, Potsdam-Rehbruecke, Germany
- Einstein Center for Neurosciences, Charite - Universitätsmedizin Berlin, Berlin, Germany
| | - Wolfgang Meyerhof
- Department of Molecular Genetics, German Institute for Human Nutrition, Potsdam-Rehbruecke, Germany
- Center for Integrative Physiology and Molecular Medicine, Saarland University, Homburg, Germany
| | - Markus Sjöblom
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Katerina Nikolovska
- Department of Gastroenterology, Hepatology, Infectiology and Endocrinology, Medical University Hannover, Hannover, Germany
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology, Infectiology and Endocrinology, Medical University Hannover, Hannover, Germany
| | - Manfred W Kilimann
- Department of Molecular Neurobiology, Max-Planck-Institute for Multidisciplinary Sciences, Göttingen, Germany.
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Sarthi JB, Trumbull AM, Abazari SM, van Unen V, Chan JE, Jiang Y, Gammons J, Anderson MO, Cil O, Kuo CJ, Sellers ZM. Key role of down-regulated in adenoma ( SLC26A3) chloride/bicarbonate exchanger in linaclotide-stimulated intestinal bicarbonate secretion upon loss of CFTR function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.05.539132. [PMID: 37205513 PMCID: PMC10187319 DOI: 10.1101/2023.05.05.539132] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Duodenal bicarbonate secretion is critical to epithelial protection, nutrient digestion/absorption and is impaired in cystic fibrosis (CF). We examined if linaclotide, typically used to treat constipation, may also stimulate duodenal bicarbonate secretion. Bicarbonate secretion was measured in vivo and in vitro using mouse and human duodenum (biopsies and enteroids). Ion transporter localization was identified with confocal microscopy and de novo analysis of human duodenal single cell RNA sequencing (sc-RNAseq) datasets was performed. Linaclotide increased bicarbonate secretion in mouse and human duodenum in the absence of CFTR expression (Cftr knockout mice) or function (CFTRinh-172). NHE3 inhibition contributed to a portion of this response. Linaclotide-stimulated bicarbonate secretion was eliminated by down-regulated in adenoma (DRA, SLC26A3) inhibition during loss of CFTR activity. Sc-RNAseq identified that 70% of villus cells expressed SLC26A3, but not CFTR, mRNA. Loss of CFTR activity and linaclotide increased apical brush border expression of DRA in non-CF and CF differentiated enteroids. These data provide further insights into the action of linaclotide and how DRA may compensate for loss of CFTR in regulating luminal pH. Linaclotide may be a useful therapy for CF individuals with impaired bicarbonate secretion.
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Affiliation(s)
- Jessica B. Sarthi
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition, Stanford University, Palo Alto, CA, USA
| | - Annie M. Trumbull
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition, Stanford University, Palo Alto, CA, USA
| | - Shayda M. Abazari
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition, Stanford University, Palo Alto, CA, USA
| | - Vincent van Unen
- Department of Medicine, Division of Hematology, Stanford University, Palo Alto, CA, USA
| | - Joshua E. Chan
- Department of Medicine, Division of Hematology, Stanford University, Palo Alto, CA, USA
| | - Yanfen Jiang
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition, Stanford University, Palo Alto, CA, USA
| | - Jesse Gammons
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition, Stanford University, Palo Alto, CA, USA
| | - Marc O. Anderson
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA, USA
| | - Onur Cil
- Department of Pediatrics, University of California San Francisco, San Francisco, CA, USA
| | - Calvin J. Kuo
- Department of Medicine, Division of Hematology, Stanford University, Palo Alto, CA, USA
| | - Zachary M. Sellers
- Department of Pediatrics, Division of Gastroenterology, Hepatology, and Nutrition, Stanford University, Palo Alto, CA, USA
- Sellers Research and Clinical Development, LLC, Newark, CA, USA
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Dominguez Rieg JA, Rieg T. New functions and roles of the Na +-H +-exchanger NHE3. Pflugers Arch 2024; 476:505-516. [PMID: 38448727 DOI: 10.1007/s00424-024-02938-9] [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: 02/05/2024] [Revised: 02/22/2024] [Accepted: 02/27/2024] [Indexed: 03/08/2024]
Abstract
The sodium/proton exchanger isoform 3 (NHE3) is expressed in the intestine and the kidney, where it contributes to hydrogen secretion and sodium (re)absorption. The roles of this transporter have been studied by the use of the respective knockout mice and by using pharmacological inhibitors. Whole-body NHE3 knockout mice suffer from a high mortality rate (with only ∼30% of mice surviving into adulthood), and based on the expression of NHE3 in both intestine and kidney, some conclusions that were originally derived were based on this rather complex phenotype. In the last decade, more refined models have been developed that added temporal and spatial control of NHE3 expression. For example, novel mouse models have been developed with a knockout of NHE3 in intestinal epithelial cells, tubule/collecting duct of the kidney, proximal tubule of the kidney, and thick ascending limb of the kidney. These refined models have significantly contributed to our understanding of the role of NHE3 in a tissue/cell type-specific manner. In addition, tenapanor was developed, which is a non-absorbable, intestine-specific NHE3 inhibitor. In rat and human studies, tenapanor lowered intestinal Pi uptake and was effective in lowering plasma Pi levels in patients on hemodialysis. Of note, diarrhea is seen as a side effect of tenapanor (with its indication for the treatment of constipation) and in intestine-specific NHE3 knockout mice; however, effects on plasma Pi were not supported by this mouse model which showed enhanced and not reduced intestinal Pi uptake. Further studies indicated that the gut microbiome in mice lacking intestinal NHE3 resembles an intestinal environment favoring the competitive advantage of inflammophilic over anti-inflammatory species, something similar seen in patients with inflammatory bowel disease. This review will highlight recent developments and summarize newly gained insight from these refined models.
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Affiliation(s)
- Jessica A Dominguez Rieg
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA
- James A. Haley Veterans' Hospital, Tampa, FL, 33612, USA
- Hypertension and Kidney Research Center, University of South Florida, Tampa, FL, 33602, USA
| | - Timo Rieg
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA.
- James A. Haley Veterans' Hospital, Tampa, FL, 33612, USA.
- Hypertension and Kidney Research Center, University of South Florida, Tampa, FL, 33602, USA.
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6
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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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Amiri M, Jiang M, Salari A, Xiu R, Alper SL, Seidler UE. Reduced surface pH and upregulated AE2 anion exchange in SLC26A3-deleted polarized intestinal epithelial cells. Am J Physiol Cell Physiol 2024; 326:C829-C842. [PMID: 38223928 PMCID: PMC11193482 DOI: 10.1152/ajpcell.00590.2023] [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: 11/03/2023] [Revised: 12/21/2023] [Accepted: 01/02/2024] [Indexed: 01/16/2024]
Abstract
Loss of function mutations in the SLC26A3 gene cause chloride-losing diarrhea in mice and humans. Although systemic adaptive changes have been documented in these patients and in the corresponding knockout mice, how colonic enterocytes adapt to loss of this highly expressed and highly regulated luminal membrane anion exchanger remains unclear. To address this question, SLC26A3 was deleted in the self-differentiating Caco2BBe colonic cell line by the CRISPR/Cas9 technique. We selected a clone with loss of SLC26A3 protein expression and morphological features indistinguishable from those of the native cell line. Neither growth curves nor development of transepithelial electrical resistance (TEER) differed between wild-type (WT) and SLC26A3 knockout (KO) cells. Real-time qPCR and Western analysis in SLC26A3-KO cells revealed an increase in AE2 expression without significant change in NHE3 expression or localization. Steady-state pHi and apical and basolateral Cl-/HCO3- exchange activities were assessed fluorometrically in a dual perfusion chamber with independent perfusion of luminal and serosal baths. Apical Cl-/HCO3- exchange rates were strongly reduced in SLC26A3-KO cells, accompanied by a surface pH more acidic than that of WT cells. Steady-state pHi was not significantly different from that of WT cells, but basolateral Cl-/HCO3- exchange rates were higher in SLC26A3-KO than in WT cells. The data show that CRISPR/Cas9-mediated SLC26A3 deletion strongly reduced apical Cl-/HCO3- exchange rate and apical surface pH, but sustained a normal steady-state pHi due to increased expression and function of basolateral AE2. The low apical surface pH resulted in functional inhibition of NHE-mediated fluid absorption despite normal expression of NHE3 polypeptide.NEW & NOTEWORTHY SLC26A3 gene mutations cause chloride-losing diarrhea. To understand how colonic enterocytes adapt, SLC26A3 was deleted in Caco2BBe cells using CRISPR/Cas9. In comparison to the wild-type cells, SLC26A3 knockout cells showed similar growth and transepithelial resistance but substantially reduced apical Cl-/HCO3- exchange rates, and an acidic surface pH. Steady-state intracellular pH was comparable between the WT and KO cells due to increased basolateral AE2 expression and function.
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Affiliation(s)
- Mahdi Amiri
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Min Jiang
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Azam Salari
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Renjie Xiu
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
| | - Seth L Alper
- Division of Nephrology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States
| | - Ursula E Seidler
- Department of Gastroenterology, Hannover Medical School, Hannover, Germany
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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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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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10
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Fan W, Tan Q. Application of the steady-state intestinal perfusion system in measuring intestinal fluid absorption and bicarbonate secretion in vivo. Front Physiol 2023; 14:1163888. [PMID: 37497438 PMCID: PMC10366686 DOI: 10.3389/fphys.2023.1163888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 06/26/2023] [Indexed: 07/28/2023] Open
Abstract
Background: The steady-state intestinal perfusion system represents a tool used in measuring intestinal fluid absorption and bicarbonate secretion in vivo; however, detailed procedures and parameters were not elucidated fully. Aim: We focused on the methods of the steady-state intestinal perfusion system comprehensively including the blood pressure, hematocrit, blood gas, and heart rate of mouse. Methods: Anesthetized, tracheally intubated, and artificially ventilated mice were used for this system. The blood pressure, hematocrit, blood gas, heart rate, and rate of fluid absorption and HCO3 - secretion of the small intestine and colon at different time points were evaluated. Results: Blood pressure, hematocrit, blood gas, and heart rate became stable at the 30 min time point after completion of surgery and could be maintained for 2 h. Rates of fluid absorption and bicarbonate secretion were also kept stable during the period of steady state of mice. Rates of fluid absorption and bicarbonate secretion were different among the jejunum, ileum, proximal, and mid-distal colon. Conclusion: The steady-state intestinal perfusion system is a reliable system for measuring intestinal fluid absorption and bicarbonate secretion in vivo.
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Carlos dos Reis D, Dastoor P, Santos AK, Sumigray K, Ameen NA. CFTR high expresser cells in cystic fibrosis and intestinal diseases. Heliyon 2023; 9:e14568. [PMID: 36967909 PMCID: PMC10031467 DOI: 10.1016/j.heliyon.2023.e14568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 03/02/2023] [Accepted: 03/09/2023] [Indexed: 03/16/2023] Open
Abstract
Cystic Fibrosis Transmembrane Conductance Regulator (CFTR), the Cl-/HCO3 - channel implicated in Cystic Fibrosis, is critical to the pathophysiology of many gastrointestinal diseases. Defects in CFTR lead to intestinal dysfunction, malabsorption, obstruction, infection, inflammation, and cancer that increases morbidity and reduces quality of life. This review will focus on CFTR in the intestine and the implications of the subpopulation of CFTR High Expresser Cells (CHEs) in Cystic Fibrosis (CF), intestinal physiology and pathophysiology of intestinal diseases.
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Affiliation(s)
- Diego Carlos dos Reis
- Department of Pediatrics/Gastroenterology and Hepatology, Yale School of Medicine, CT, 06510, USA
| | - Parinaz Dastoor
- Department of Pediatrics/Gastroenterology and Hepatology, Yale School of Medicine, CT, 06510, USA
| | - Anderson Kenedy Santos
- Department of Pediatrics/Gastroenterology and Hepatology, Yale School of Medicine, CT, 06510, USA
- Department of Genetics, Yale School of Medicine, New Haven, CT, 06510, USA
| | - Kaelyn Sumigray
- Department of Genetics, Yale School of Medicine, New Haven, CT, 06510, USA
- Yale Stem Cell Center, Yale School of Medicine, New Haven, CT, 06510, USA
- Yale Cancer Center, Yale School of Medicine, New Haven, CT, 06510, USA
| | - Nadia A. Ameen
- Department of Pediatrics/Gastroenterology and Hepatology, Yale School of Medicine, CT, 06510, USA
- Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT06510, USA
- Corresponding author. Department of Pediatrics/Gastroenterology and Hepatology, Yale School of Medicine, CT, 06510, USA.
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12
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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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13
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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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14
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Dong Y, Li H, Ilie A, Gao Y, Boucher A, Zhang XC, Orlowski J, Zhao Y. Structural basis of autoinhibition of the human NHE3-CHP1 complex. SCIENCE ADVANCES 2022; 8:eabn3925. [PMID: 35613257 PMCID: PMC9132474 DOI: 10.1126/sciadv.abn3925] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 04/11/2022] [Indexed: 06/15/2023]
Abstract
Sodium-proton exchanger 3 (NHE3/SLC9A3) located in the apical membrane of renal and gastrointestinal epithelia mediates salt and fluid absorption and regulates pH homeostasis. As an auxiliary regulatory factor of NHE proteins, calcineurin B homologous protein 1 (CHP1) facilitates NHE3 maturation, plasmalemmal expression, and pH sensitivity. Dysfunctions of NHE3 are associated with renal and digestive system disorders. Here, we report the cryo-electron microscopy structure of the human NHE3-CHP1 complex in its inward-facing conformation. We found that a cytosolic helix-loop-helix motif in NHE3 blocks the intracellular cavity formed between the core and dimerization domains, functioning as an autoinhibitory element and hindering substrate transport. Furthermore, two phosphatidylinositol molecules are found to bind to the peripheric juxtamembrane sides of the complex, function as anchors to stabilize the complex, and may thus enhance its transport activity.
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Affiliation(s)
- Yanli Dong
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hang Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Alina Ilie
- Department of Physiology, McGill University, Montreal, Canada
| | - Yiwei Gao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Annie Boucher
- Department of Physiology, McGill University, Montreal, Canada
| | - Xuejun Cai Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - John Orlowski
- Department of Physiology, McGill University, Montreal, Canada
| | - Yan Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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Nikolovska K, Seidler UE, Stock C. The Role of Plasma Membrane Sodium/Hydrogen Exchangers in Gastrointestinal Functions: Proliferation and Differentiation, Fluid/Electrolyte Transport and Barrier Integrity. Front Physiol 2022; 13:899286. [PMID: 35665228 PMCID: PMC9159811 DOI: 10.3389/fphys.2022.899286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 04/19/2022] [Indexed: 12/11/2022] Open
Abstract
The five plasma membrane Na+/H+ exchanger (NHE) isoforms in the gastrointestinal tract are characterized by distinct cellular localization, tissue distribution, inhibitor sensitivities, and physiological regulation. NHE1 (Slc9a1) is ubiquitously expressed along the gastrointestinal tract in the basolateral membrane of enterocytes, but so far, an exclusive role for NHE1 in enterocyte physiology has remained elusive. NHE2 (Slc9a2) and NHE8 (Slc9a8) are apically expressed isoforms with ubiquitous distribution along the colonic crypt axis. They are involved in pHi regulation of intestinal epithelial cells. Combined use of a knockout mouse model, intestinal organoid technology, and specific inhibitors revealed previously unrecognized actions of NHE2 and NHE8 in enterocyte proliferation and differentiation. NHE3 (Slc9a3), expressed in the apical membrane of differentiated intestinal epithelial cells, functions as the predominant nutrient-independent Na+ absorptive mechanism in the gut. The new selective NHE3 inhibitor (Tenapanor) allowed discovery of novel pathophysiological and drug-targetable NHE3 functions in cystic-fibrosis associated intestinal obstructions. NHE4, expressed in the basolateral membrane of parietal cells, is essential for parietal cell integrity and acid secretory function, through its role in cell volume regulation. This review focuses on the expression, regulation and activity of the five plasma membrane Na+/H+ exchangers in the gastrointestinal tract, emphasizing their role in maintaining intestinal homeostasis, or their impact on disease pathogenesis. We point to major open questions in identifying NHE interacting partners in central cellular pathways and processes and the necessity of determining their physiological role in a system where their endogenous expression/activity is maintained, such as organoids derived from different parts of the gastrointestinal tract.
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Kini A, Zhao B, Basic M, Roy U, Iljazovic A, Odak I, Ye Z, Riederer B, Di Stefano G, Römermann D, Koenecke C, Bleich A, Strowig T, Seidler U. Upregulation of antimicrobial peptide expression in slc26a3-/- mice with colonic dysbiosis and barrier defect. Gut Microbes 2022; 14:2041943. [PMID: 35230892 PMCID: PMC8890434 DOI: 10.1080/19490976.2022.2041943] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Genetic defects in SLC26A3 (DRA), an intestinal Cl-/HCO3- exchanger, result in congenital chloride diarrhea (CLD), marked by lifelong acidic diarrhea and a high risk of inflammatory bowel disease. Slc26a3-/- mice serve as a model to understand the pathophysiology of CLD and search for treatment options. This study investigates the microbiota changes in slc26a3-/- colon, the genotype-related causes for the observed microbiota alterations, its inflammatory potential, as well as the corresponding host responses. The luminal and the mucosa-adherent cecal and colonic microbiota of cohoused slc26a3-/- and wt littermates were analyzed by 16S rRNA gene sequencing. Fecal microbiota transfer from cohoused slc26a3-/- and wt littermates to germ-free wt mice was performed to analyze the stability and the inflammatory potential of the communities.The cecal and colonic luminal and mucosa-adherent microbiota of slc26a3-/- mice was abnormal from an early age, with a loss of diversity, of short-chain fatty acid producers, and an increase of pathobionts. The transfer of slc26a3-/- microbiota did not result in intestinal inflammation and the microbial diversity in the recipient mice normalized over time. A strong increase in the expression of Il22, Reg3β/γ, Relmβ, and other proteins with antimicrobial functions was observed in slc26a3-/- colon from juvenile age, while the mucosal and systemic inflammatory signature was surprisingly mild. The dysbiotic microbiota, low mucosal pH, and mucus barrier defect in slc26a3-/- colon are accompanied by a stark upregulation of the expression of a panel of antimicrobial proteins. This may explain the low inflammatory burden in the gut of these mice.
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Affiliation(s)
| | - Bei Zhao
- Microbial Immune Regulation Research Group, Helmholtz Center for Infection Research, Braunschweig, Germany
| | | | - Urmi Roy
- Microbial Immune Regulation Research Group, Helmholtz Center for Infection Research, Braunschweig, Germany
| | - Aida Iljazovic
- Microbial Immune Regulation Research Group, Helmholtz Center for Infection Research, Braunschweig, Germany
| | - Ivan Odak
- Institute of Immunology Hannover Medical School Hannover, Germany
| | | | | | | | | | | | | | - Till Strowig
- Microbial Immune Regulation Research Group, Helmholtz Center for Infection Research, Braunschweig, Germany
| | - Ursula Seidler
- Department of Gastroenterology,CONTACT Ursula Seidler Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Carl Neuberg Straße 1, D30625, Hannover.de, Germany
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17
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Amiri M, Seidler UE, Nikolovska K. The Role of pH i in Intestinal Epithelial Proliferation-Transport Mechanisms, Regulatory Pathways, and Consequences. Front Cell Dev Biol 2021; 9:618135. [PMID: 33553180 PMCID: PMC7862550 DOI: 10.3389/fcell.2021.618135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 01/04/2021] [Indexed: 01/07/2023] Open
Abstract
During the maturation of intestinal epithelial cells along the crypt/surface axis, a multitude of acid/base transporters are differentially expressed in their apical and basolateral membranes, enabling processes of electrolyte, macromolecule, nutrient, acid/base and fluid secretion, and absorption. An intracellular pH (pHi)-gradient is generated along the epithelial crypt/surface axis, either as a consequence of the sum of the ion transport activities or as a distinctly regulated entity. While the role of pHi on proliferation, migration, and tumorigenesis has been explored in cancer cells for some time, emerging evidence suggests an important role of the pHi in the intestinal stem cells (ISCs) proliferative rate under physiological conditions. The present review highlights the current state of knowledge about the potential regulatory role of pHi on intestinal proliferation and differentiation.
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