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Tian L, Andrews C, Yan Q, Yang JJ. Molecular regulation of calcium-sensing receptor (CaSR)-mediated signaling. Chronic Dis Transl Med 2024; 10:167-194. [PMID: 39027195 PMCID: PMC11252437 DOI: 10.1002/cdt3.123] [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: 03/04/2024] [Revised: 03/29/2024] [Accepted: 04/09/2024] [Indexed: 07/20/2024] Open
Abstract
Calcium-sensing receptor (CaSR), a family C G-protein-coupled receptor, plays a crucial role in regulating calcium homeostasis by sensing small concentration changes of extracellular Ca2+, Mg2+, amino acids (e.g., L-Trp and L-Phe), small peptides, anions (e.g., HCO3 - and PO4 3-), and pH. CaSR-mediated intracellular Ca2+ signaling regulates a diverse set of cellular processes including gene transcription, cell proliferation, differentiation, apoptosis, muscle contraction, and neuronal transmission. Dysfunction of CaSR with mutations results in diseases such as autosomal dominant hypocalcemia, familial hypocalciuric hypercalcemia, and neonatal severe hyperparathyroidism. CaSR also influences calciotropic disorders, such as osteoporosis, and noncalciotropic disorders, such as cancer, Alzheimer's disease, and pulmonary arterial hypertension. This study first reviews recent advances in biochemical and structural determination of the framework of CaSR and its interaction sites with natural ligands, as well as exogenous positive allosteric modulators and negative allosteric modulators. The establishment of the first CaSR protein-protein interactome network revealed 94 novel players involved in protein processing in endoplasmic reticulum, trafficking, cell surface expression, endocytosis, degradation, and signaling pathways. The roles of these proteins in Ca2+-dependent cellular physiological processes and in CaSR-dependent cellular signaling provide new insights into the molecular basis of diseases caused by CaSR mutations and dysregulated CaSR activity caused by its protein interactors and facilitate the design of therapeutic agents that target CaSR and other family C G-protein-coupled receptors.
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Affiliation(s)
- Li Tian
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
| | - Corey Andrews
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
| | - Qiuyun Yan
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
| | - Jenny J. Yang
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging FacilityGeorgia State UniversityAtlantaGeorgiaUSA
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Reeves KD, Figuereo YF, Weis VG, Hsu FC, Engevik MA, Krigsman A, Walker SJ. Mapping the geographical distribution of the mucosa-associated gut microbiome in GI-symptomatic children with autism spectrum disorder. Am J Physiol Gastrointest Liver Physiol 2024; 327:G217-G234. [PMID: 38887795 PMCID: PMC11637567 DOI: 10.1152/ajpgi.00101.2024] [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: 03/28/2024] [Revised: 05/16/2024] [Accepted: 06/11/2024] [Indexed: 06/20/2024]
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by cognitive, behavioral, and communication impairments. In the past few years, it has been proposed that alterations in the gut microbiota may contribute to an aberrant communication between the gut and brain in children with ASD. Consistent with this notion, several studies have demonstrated that children with ASD have an altered fecal microbiota compared with typically developing (TD) children. However, it is unclear where along the length of the gastrointestinal (GI) tract these alterations in microbial communities occur. In addition, the variation between specific mucosa-associated communities remains unknown. To address this gap in knowledge of the microbiome associated with ASD, biopsies from the antrum, duodenum, ileum, right colon, and rectum of children with ASD and age- and sex-matched TD children were examined by 16S rRNA sequencing. We observed an overall elevated abundance of Bacillota and Bacteroidota and a decreased abundance of Pseudomonadota in all GI tract regions of both male and female children with ASD compared with TD children. Further analysis at the genera level revealed unique differences in the microbiome in the different regions of the GI tract in children with ASD compared with TD children. We also observed sex-specific differences in the gut microbiota composition in children with ASD. These data indicate that the microbiota of children with ASD is altered in multiple regions of the GI tract and that different anatomic locations have unique alterations in mucosa-associated bacterial genera.NEW & NOTEWORTHY Analysis in stool samples has shown gut microbiota alterations in children with autism spectrum disorder (ASD) compared with typically developing (TD) children. However, it is unclear which segment(s) of the gut exhibit alterations in microbiome composition. In this study, we examined microbiota composition along the gastrointestinal (GI) tract in the stomach, duodenum, ileum, right colon, and rectum. We found site-specific and sex-specific differences in the gut microbiota of children with ASD, compared with controls.
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Affiliation(s)
- Kimberly D Reeves
- Center for Precision Medicine, Wake Forest University Health Sciences, Winston-Salem, North Carolina, United States
- Section on Molecular Medicine, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem North Carolina, United States
| | - Yosauri F Figuereo
- Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States
| | - Victoria G Weis
- Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States
| | - Fang-Chi Hsu
- Department of Biostatistics and Data Science, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States
| | - Melinda A Engevik
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, United States
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina, United States
| | - Arthur Krigsman
- Pediatric Gastroenterology Resources, Georgetown, Texas, United States
| | - Stephen J Walker
- Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States
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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: 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: 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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Cheng Z, Zhou Y, Xiong X, Li L, Chen Z, Wu F, Dong R, Liu Q, Zhao Y, Jiang S, Yu Q, Chen G. Traditional herbal pair Portulacae Herba and Granati Pericarpium alleviates DSS-induced colitis in mice through IL-6/STAT3/SOCS3 pathway. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2024; 126:155283. [PMID: 38422652 DOI: 10.1016/j.phymed.2023.155283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 12/01/2023] [Accepted: 12/13/2023] [Indexed: 03/02/2024]
Abstract
BACKGROUND Portulacae Herba and Granati Pericarpium pair (PGP) is a traditional Chinese herbal medicine treatment for colitis, clinically demonstrating a relatively favorable effect on relieving diarrhea and abnormal stools. However, the underlying mechanism remain uncertain. PURPOSE The present study intends to evaluate the efficacy of PGP in treating colitis in mice and investigate its underlying mechanism. METHODS The protective effect of PGP against colitis was determined by monitoring body weight, colon length, colon weight, and survival rate in mice. Colonic inflammation was assessed by serum cytokine levels, colonic H&E staining, and local neutrophil infiltration. The reversal of intestinal epithelial barrier damage by PGP was subsequently analyzed with Western blot and histological staining. Furthermore, RNA-seq analysis and molecular docking were performed to identify potential pathways recruited by PGP. Following the hints of the transcriptomic results, the role of PGP through the IL-6/STAT3/SOCS3 pathway in DSS-induced colitis mice was verified by Western blot. RESULTS DSS-induced colitis in mice was significantly curbed by PGP treatment. PGP treatment significantly mitigated DSS-induced colitis in mice, as evidenced by improvements in body weight, DAI severity, survival rate, and inflammatory cytokines levels in serum and colon. Moreover, PGP treatment up-regulated the level of Slc26a3, thereby increasing the expressions of the tight junction/adherens junction proteins ZO-1, occludin and E-cadherin in the colon. RNA-seq analysis revealed that PGP inhibits the IL-6/STAT3/SOCS3 pathway at the transcriptional level. Molecular docking indicated that the major components of PGP could bind tightly to the proteins of IL-6 and SOCS3. Meanwhile, the result of Western blot revealed that the IL-6/STAT3/SOCS3 pathway was inhibited at the protein level after PGP administration. CONCLUSION PGP could alleviate colonic inflammation and reverse damage to the intestinal epithelial barrier in DSS-induced colitis mice. The underlying mechanism involves the inhibition of the IL-6/STAT3/SOCS3 pathway.
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Affiliation(s)
- Zhe Cheng
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yi Zhou
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xinyu Xiong
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Lingli Li
- Department of Traditional Chinese Medicine, Wuhan Fourth Hospital, Wuhan 430033, China
| | - Zekai Chen
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Fan Wu
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Ruolan Dong
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Qiong Liu
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yan Zhao
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Shujun Jiang
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Qin Yu
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Guang Chen
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
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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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Sarker R, Lin R, Singh V, Donowitz M, Tse CM. SLC26A3 (DRA) is stimulated in a synergistic, intracellular Ca 2+-dependent manner by cAMP and ATP in intestinal epithelial cells. Am J Physiol Cell Physiol 2023; 324:C1263-C1273. [PMID: 37154494 PMCID: PMC10243534 DOI: 10.1152/ajpcell.00523.2022] [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: 11/17/2022] [Revised: 04/24/2023] [Accepted: 04/24/2023] [Indexed: 05/10/2023]
Abstract
In polarized intestinal epithelial cells, downregulated in adenoma (DRA) is an apical Cl-/[Formula: see text] exchanger that is part of neutral NaCl absorption under baseline conditions, but in cyclic adenosine monophosphate (cAMP)-driven diarrheas, it is stimulated and contributes to increased anion secretion. To further understand the regulation of DRA in conditions mimicking some diarrheal diseases, Caco-2/BBE cells were exposed to forskolin (FSK) and adenosine 5'-triphosphate (ATP). FSK and ATP stimulated DRA in a concentration-dependent manner, with ATP acting via P2Y1 receptors. FSK at 1 µM and ATP at 0.25 µM had minimal to no effect on DRA given individually; however, together, they stimulated DRA to levels seen with maximum concentrations of FSK and ATP alone. In Caco-2/BBE cells expressing the Ca2+ indicator GCaMP6s, ATP increased intracellular Ca2+ (Ca2+i) in a concentration-dependent manner, whereas FSK (1 µM), which by itself did not significantly alter Ca2+i, followed by 0.25 µM ATP produced a large increase in Ca2+ that was approximately equal to the elevation caused by 1 µM ATP. 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis(acetoxymethyl ester) (BAPTA-AM) pretreatment prevented the ATP and FSK/ATP synergistically increased the DRA activity and the increase in Ca2+i caused by FSK/ATP. FSK/ATP synergistic stimulation of DRA was similarly observed in human colonoids. In Caco-2/BBE cells, subthreshold concentrations of FSK (cAMP) and ATP (Ca2+) synergistically increased Ca2+i and stimulated DRA activity with both being blocked by BAPTA-AM pretreatment. Diarrheal diseases, such as bile acid diarrhea, in which both cAMP and Ca2+ are elevated, are likely to be associated with stimulated DRA activity contributing to increased anion secretion, whereas separation of DRA from Na+/H+ exchanger isoform-3 (NHE3) contributes to reduced NaCl absorption.NEW & NOTEWORTHY The BB Cl-/[Formula: see text] exchanger DRA takes part in both neutral NaCl absorption and stimulated anion secretion. Using intestinal cell line, Caco-2/BBE high concentrations of cAMP and Ca2+ individually stimulated DRA activity, whereas low concentrations, which had no/minimal effect, synergistically stimulated DRA activity that required a synergistic increase in intracellular Ca2+. This study increases understanding of diarrheal diseases, such as bile salt diarrhea, in which both cAMP and elevated Ca2+ are involved.
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Affiliation(s)
- Rafiquel Sarker
- Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Ruxian Lin
- Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Varsha Singh
- Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Mark Donowitz
- Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Chung-Ming Tse
- Division of Gastroenterology and Hepatology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
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Salari A, Zhou K, Nikolovska K, Seidler U, Amiri M. Human Colonoid-Myofibroblast Coculture for Study of Apical Na +/H + Exchangers of the Lower Cryptal Neck Region. Int J Mol Sci 2023; 24:ijms24054266. [PMID: 36901695 PMCID: PMC10001859 DOI: 10.3390/ijms24054266] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 02/17/2023] [Accepted: 02/18/2023] [Indexed: 02/25/2023] Open
Abstract
Cation and anion transport in the colonocyte apical membrane is highly spatially organized along the cryptal axis. Because of lack of experimental accessibility, information about the functionality of ion transporters in the colonocyte apical membrane in the lower part of the crypt is scarce. The aim of this study was to establish an in vitro model of the colonic lower crypt compartment, which expresses the transit amplifying/progenitor (TA/PE) cells, with accessibility of the apical membrane for functional study of lower crypt-expressed Na+/H+ exchangers (NHEs). Colonic crypts and myofibroblasts were isolated from human transverse colonic biopsies, expanded as three-dimensional (3D) colonoids and myofibroblast monolayers, and characterized. Filter-grown colonic myofibroblast-colonic epithelial cell (CM-CE) cocultures (myofibroblasts on the bottom of the transwell and colonocytes on the filter) were established. The expression pattern for ion transport/junctional/stem cell markers of the CM-CE monolayers was compared with that of nondifferentiated (EM) and differentiated (DM) colonoid monolayers. Fluorometric pHi measurements were performed to characterize apical NHEs. CM-CE cocultures displayed a rapid increase in transepithelial electrical resistance (TEER), paralleled by downregulation of claudin-2. They maintained proliferative activity and an expression pattern resembling TA/PE cells. The CM-CE monolayers displayed high apical Na+/H+ exchange activity, mediated to >80% by NHE2. Human colonoid-myofibroblast cocultures allow the study of ion transporters that are expressed in the apical membrane of the nondifferentiated colonocytes of the cryptal neck region. The NHE2 isoform is the predominant apical Na+/H+ exchanger in this epithelial compartment.
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Affiliation(s)
- Azam Salari
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625 Hannover, Germany
| | - Kunyan Zhou
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625 Hannover, Germany
- Department of Thyroid Surgery, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310027, China
| | - Katerina Nikolovska
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625 Hannover, Germany
| | - Ursula Seidler
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625 Hannover, Germany
- Correspondence: (U.S.); (M.A.); Tel.: +49-511-532-9427 (U.S.); Fax: +49-511-532-8428 (U.S.)
| | - Mahdi Amiri
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, 30625 Hannover, Germany
- Correspondence: (U.S.); (M.A.); Tel.: +49-511-532-9427 (U.S.); Fax: +49-511-532-8428 (U.S.)
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Whittamore JM, Hatch M. Oxalate secretion is stimulated by a cAMP-dependent pathway in the mouse cecum. Pflugers Arch 2023; 475:249-266. [PMID: 36044064 PMCID: PMC9851989 DOI: 10.1007/s00424-022-02742-3] [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: 06/06/2022] [Revised: 08/06/2022] [Accepted: 08/18/2022] [Indexed: 02/01/2023]
Abstract
Elevated levels of the intracellular second messenger cAMP can stimulate intestinal oxalate secretion however the membrane transporters responsible are unclear. Oxalate transport by the chloride/bicarbonate (Cl-/HCO3-) exchanger Slc26a6 or PAT-1 (Putative Anion Transporter 1), is regulated via cAMP when expressed in Xenopus oocytes and cultured cells but whether this translates to the native epithelia is unknown. This study investigated the regulation of oxalate transport by the mouse intestine focusing on transport at the apical membrane hypothesizing PAT-1 is the target of a cAMP-dependent signaling pathway. Adopting the Ussing chamber technique we measured unidirectional 14C-oxalate and 36Cl- flux ([Formula: see text] and [Formula: see text]) across distal ileum, cecum and distal colon, employing forskolin (FSK) and 3-isobutyl-1-methylxanthine (IBMX) to trigger cAMP production. FSK/IBMX initiated a robust secretory response by all segments but the stimulation of net oxalate secretion was confined to the cecum only involving activation of [Formula: see text] and distinct from net Cl- secretion produced by inhibiting [Formula: see text]. Using the PAT-1 knockout (KO) mouse we determined cAMP-stimulated [Formula: see text] was not directly dependent on PAT-1, but it was sensitive to mucosal DIDS (4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid), although unlikely to be another Cl-/HCO3- exchanger given the lack of trans-stimulation or cis-inhibition by luminal Cl- or HCO3-. The cAMP-activated oxalate efflux was reliant on CFTR (Cystic Fibrosis Transmembrane conductance Regulator) activity, but only in the presence of PAT-1, leading to speculation on the involvement of a multi-transporter regulatory complex. Further investigations at the cellular and molecular level are necessary to define the mechanism and transporter(s) responsible.
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Affiliation(s)
- Jonathan M Whittamore
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA.
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research | Internal Medicine, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX, 75390-8885, USA.
| | - Marguerite Hatch
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
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Peritore-Galve FC, Kaji I, Smith A, Walker LM, Shupe JA, Washington MK, Algood HMS, Dudeja PK, Goldenring JR, Lacy DB. Increased intestinal permeability and downregulation of absorptive ion transporters Nhe3, Dra, and Sglt1 contribute to diarrhea during Clostridioides difficile infection. Gut Microbes 2023; 15:2225841. [PMID: 37350393 PMCID: PMC10291935 DOI: 10.1080/19490976.2023.2225841] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 06/09/2023] [Indexed: 06/24/2023] Open
Abstract
BACKGROUND & AIM Clostridioides difficile infection (CDI) is the leading cause of hospital-acquired diarrhea and pseudomembranous colitis. Two protein toxins, TcdA and TcdB, produced by C. difficile are the major determinants of disease. However, the pathophysiological causes of diarrhea during CDI are not well understood. Here, we investigated the effects of C. difficile toxins on paracellular permeability and apical ion transporters in the context of an acute physiological infection. METHODS We studied intestinal permeability and apical membrane transporters in female C57BL/6J mice. Üssing chambers were used to measure paracellular permeability and ion transporter function across the intestinal tract. Infected intestinal tissues were analyzed by immunofluorescence microscopy and RNA-sequencing to uncover mechanisms of transporter dysregulation. RESULTS Intestinal permeability was increased through the size-selective leak pathway in vivo during acute CDI in a 2-day-post infection model. Chloride secretory activity was reduced in the cecum and distal colon during infection by decreased CaCC and CFTR function, respectively. SGLT1 activity was significantly reduced in the cecum and colon, accompanied by ablated SGLT1 expression in colonocytes and increased luminal glucose concentrations. SGLT1 and DRA expression was ablated by either TcdA or TcdB during acute infection, but NHE3 was decreased in a TcdB-dependent manner. The localization of key proteins that link filamentous actin to the ion transporters in the apical plasma membrane was unchanged. However, Sglt1, Nhe3, and Dra were drastically reduced at the transcript level, implicating downregulation of ion transporters in the mechanism of diarrhea during CDI. CONCLUSIONS CDI increases intestinal permeability and decreases apical abundance of NHE3, SGLT1, and DRA. This combination likely leads to dysfunctional water and solute absorption in the large bowel, causing osmotic diarrhea. These findings provide insights into the pathophysiological mechanisms underlying diarrhea and may open novel avenues for attenuating CDI-associated diarrhea.
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Affiliation(s)
- F. Christopher Peritore-Galve
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Izumi Kaji
- Section of Surgical Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
- Epithelial Biology Center, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Anna Smith
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Lauren M. Walker
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Vaccine Center, Vanderbilt University Medical Center, Nashville, TN, USA
| | - John A. Shupe
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
| | - M. Kay Washington
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Holly M. Scott Algood
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Pradeep K. Dudeja
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, IL, USA
- Department of Veterans Affairs, Jesse Brown Veterans Affairs Medical Center, Chicago, IL, USA
| | - James R. Goldenring
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
- Section of Surgical Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
- Epithelial Biology Center, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, USA
- Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - D. Borden Lacy
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, USA
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10
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Zhang T, Zhu T, Wen J, Chen Y, Wang L, Lv X, Yang W, Jia Y, Qu C, Li H, Wang H, Qu L, Ning Z. Gut microbiota and transcriptome analysis reveals a genetic component to dropping moisture in chickens. Poult Sci 2022; 102:102242. [PMID: 36931071 PMCID: PMC10036737 DOI: 10.1016/j.psj.2022.102242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 06/11/2022] [Accepted: 06/14/2022] [Indexed: 03/12/2023] Open
Abstract
High dropping moisture (DM) in poultry production has deleterious effects on the environment, feeding cost, and public health of people and animals. To explore the contributing genetic components, we classified DM of 67-wk-old Rhode Island Red (RIR) hens at 4 different levels and evaluated the underlying genetic heritability. We found the heritability of DM to be 0.219, indicating a moderately heritable trait. We then selected chickens with the highest and lowest DM levels. Using transcriptome, we only detected 12 differentially expressed genes (DEGs) between these 2 groups from the spleen, and 1,507 DEGs from intestinal tissues (jejunum and cecum). The low number of DEGs observed in the spleen suggests that differing moisture levels are not attributed to pathogenic infection. Fourteen of the intestinal high expressed genes are associated with water-salt metabolism (WSM). We also investigated the gut microbial composition by 16S rRNA gene amplicon sequencing. Six different microbial operational taxonomic units (OTUs) (Cetobacterium, Sterolibacterium, Elusimicrobium, Roseburia, Faecalicoccus, and Megamonas) between the 2 groups from jejunum and cecum are potentially biomarkers related to DM levels. Our results identify a genetic component to chicken DM, and can guide breeding strategies.
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Affiliation(s)
- Tongyu Zhang
- State Key Laboratory of Animal Nutrition, Department of Animal Genetics and Breeding, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Tao Zhu
- State Key Laboratory of Animal Nutrition, Department of Animal Genetics and Breeding, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Junhui Wen
- State Key Laboratory of Animal Nutrition, Department of Animal Genetics and Breeding, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Yu Chen
- Beijing Animal Husbandry and Veterinary Station, Beijing, China
| | - Liang Wang
- Beijing Animal Husbandry and Veterinary Station, Beijing, China
| | - Xueze Lv
- Beijing Animal Husbandry and Veterinary Station, Beijing, China
| | - Weifang Yang
- Beijing Animal Husbandry and Veterinary Station, Beijing, China
| | - Yaxiong Jia
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Changqing Qu
- Engineering Technology Research Center of Anti-aging Chinese Herbal Medicine of Anhui Province, Fuyang Normal University, Fuyang, China
| | - Haiying Li
- College of Animal Science, Xinjiang Agricultural University, Urumqi, China
| | - Huie Wang
- College of Animal Science, Tarim University, Xinjiang, China
| | - Lujiang Qu
- State Key Laboratory of Animal Nutrition, Department of Animal Genetics and Breeding, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China.
| | - Zhonghua Ning
- State Key Laboratory of Animal Nutrition, Department of Animal Genetics and Breeding, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China.
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11
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Flux coupling, not specificity, shapes the transport and phylogeny of SLC6 glycine transporters. Proc Natl Acad Sci U S A 2022; 119:e2205874119. [PMID: 36191186 PMCID: PMC9564218 DOI: 10.1073/pnas.2205874119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
ATB[Formula: see text] (SLC6A14) is a member of the amino acid transporter branch of the SLC6 family along with GlyT1 (SLC6A9) and GlyT2 (SLC6A5), two glycine-specific transporters coupled to 2:1 and 3:1 Na[Formula: see text]:Cl[Formula: see text], respectively. In contrast, ATB[Formula: see text] exhibits broad substrate specificity for all neutral and cationic amino acids, and its ionic coupling remains unsettled. Using the reversal potential slope method, we demonstrate a 3:1:1 Na[Formula: see text]:Cl[Formula: see text]:Gly stoichiometry for ATB[Formula: see text] that is consistent with its 2.1 e/Gly charge coupling. Like GlyT2, ATB[Formula: see text] behaves as a unidirectional transporter with virtually no glycine efflux at negative potentials after uptake, except by heteroexchange as remarkably shown by leucine activation of NMDARs in Xenopus oocytes coexpressing both membrane proteins. Analysis and computational modeling of the charge movement of ATB[Formula: see text] reveal a higher affinity for sodium in the absence of substrate than GlyT2 and a gating mechanism that locks Na[Formula: see text] into the apo-transporter at depolarized potentials. A 3:1 Na[Formula: see text]:Cl[Formula: see text] stoichiometry justifies the concentrative transport properties of ATB[Formula: see text] and explains its trophic role in tumor growth, while rationalizing its phylogenetic proximity to GlyT2 despite their extreme divergence in specificity.
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12
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Colonic Fluid and Electrolyte Transport 2022: An Update. Cells 2022; 11:cells11101712. [PMID: 35626748 PMCID: PMC9139964 DOI: 10.3390/cells11101712] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 05/16/2022] [Accepted: 05/17/2022] [Indexed: 01/25/2023] Open
Abstract
Colonic epithelial cells are responsible for maintaining a delicate balance between luminal secretion and the absorption of fluids and ions. This review aims to discuss and update the model of colonic electrolyte secretion and absorption via the cystic fibrosis transmembrane regulator (CFTR), epithelial sodium channel (ENaC), Na-K-Cl cotransporters (NKCC1 and 2), Na-H exchangers (NHE1–4), colonic H,KATPase, and several other key components involved in multi-level transepithelial ion transport. Developments in our understanding of the activity, regulation, localization, and relationships of these ion transporters and their interactions have helped forge a more robust understanding of colonic ion movement that accounts for the colonic epithelium’s role in mucosal pH modulation, the setting of osmotic gradients pivotal for fluid retention and secretion, and cell death regulation. Deviations from homeostatic ion transport cause diarrhea, constipation, and epithelial cell death and contribute to cystic fibrosis, irritable bowel syndrome (IBS), ulcerative colitis, and cancer pathologies. Signal transduction pathways that regulate electrolyte movement and the regulatory relationships between various sensors and transporters (CFTR as a target of CaSR regulation and as a regulator of ENaC and DRA, for example) are imperative aspects of a dynamic and comprehensive model of colonic ion homeostasis.
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13
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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: 13] [Impact Index Per Article: 4.3] [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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14
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Whittamore JM, Hatch M. Oxalate Flux Across the Intestine: Contributions from Membrane Transporters. Compr Physiol 2021; 12:2835-2875. [PMID: 34964122 DOI: 10.1002/cphy.c210013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Epithelial oxalate transport is fundamental to the role occupied by the gastrointestinal (GI) tract in oxalate homeostasis. The absorption of dietary oxalate, together with its secretion into the intestine, and degradation by the gut microbiota, can all influence the excretion of this nonfunctional terminal metabolite in the urine. Knowledge of the transport mechanisms is relevant to understanding the pathophysiology of hyperoxaluria, a risk factor in kidney stone formation, for which the intestine also offers a potential means of treatment. The following discussion presents an expansive review of intestinal oxalate transport. We begin with an overview of the fate of oxalate, focusing on the sources, rates, and locations of absorption and secretion along the GI tract. We then consider the mechanisms and pathways of transport across the epithelial barrier, discussing the transcellular, and paracellular components. There is an emphasis on the membrane-bound anion transporters, in particular, those belonging to the large multifunctional Slc26 gene family, many of which are expressed throughout the GI tract, and we summarize what is currently known about their participation in oxalate transport. In the final section, we examine the physiological stimuli proposed to be involved in regulating some of these pathways, encompassing intestinal adaptations in response to chronic kidney disease, metabolic acid-base disorders, obesity, and following gastric bypass surgery. There is also an update on research into the probiotic, Oxalobacter formigenes, and the basis of its unique interaction with the gut epithelium. © 2021 American Physiological Society. Compr Physiol 11:1-41, 2021.
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Affiliation(s)
- Jonathan M Whittamore
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Marguerite Hatch
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA
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15
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Takemura M, Tanaka Y, Inoue K, Tamai I, Shirasaka Y. Influence of osmolality on gastrointestinal fluid volume and drug absorption: potential impact on oral salt supplementation. J Pharm Health Care Sci 2021; 7:29. [PMID: 34465382 PMCID: PMC8408929 DOI: 10.1186/s40780-021-00212-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 06/10/2021] [Indexed: 12/04/2022] Open
Abstract
Background The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is the most frequent cause of hyponatremia in patients with cerebrovascular disease, and is often treated with oral salt tablets. However, we have shown that osmolality-dependent variations in gastrointestinal (GI) fluid volume can alter the concentration of a poorly permeable drug in the GI tract, potentially affecting its absorption. Here, we examined the effect of ingestion of hyperosmotic solution (10% NaCl) on drug concentration and absorption in the GI tract. Methods The effects of osmolality on luminal fluid volume and drug absorption in rat intestine (jejunum, ileum and colon) were examined by means of an in situ closed loop method using fluorescein isothiocyanate-dextran 4000 (FD-4) and atenolol. In vivo absorption in rats was determined by measuring the plasma concentration after oral administration of the test compounds dissolved in purified water or hyperosmotic solution (10% NaCl). Results Administration of hyperosmotic solution directly into the GI tract significantly increased the GI fluid volume, owing to secretion of water into the lumen. After administration in hyperosmotic solution, the luminal concentration of non-permeable FD-4 was significantly lower than the initial dosing concentration, whereas after administration in purified water, the luminal concentration exceeded the initial concentration. The fraction absorbed of atenolol was markedly lower after administration in hyperosmotic solution than after administration in purified water. An in vivo pharmacokinetic study in rats was consistent with these findings. Conclusions Administration of hyperosmotic NaCl solution increased GI fluid volume and reduced the plasma level of orally administered atenolol. This may imply that oral salt tablets used to treat hyponatremia in SIADH patients could decrease the intestinal absorption of concomitantly administered drugs, resulting in lower plasma exposure.
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Affiliation(s)
- Miyuki Takemura
- Faculty of Pharmacy, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan.,School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan
| | - Yuki Tanaka
- School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan
| | - Katsuhisa Inoue
- School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan
| | - Ikumi Tamai
- Faculty of Pharmacy, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan
| | - Yoshiyuki Shirasaka
- Faculty of Pharmacy, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan. .,School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan.
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16
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Stephens CE, Whittamore JM, Hatch M. The role of NHE3 (Slc9a3) in oxalate and sodium transport by mouse intestine and regulation by cAMP. Physiol Rep 2021; 9:e14828. [PMID: 33904662 PMCID: PMC8077127 DOI: 10.14814/phy2.14828] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/01/2021] [Accepted: 03/09/2021] [Indexed: 12/14/2022] Open
Abstract
Intestinal oxalate transport involves Cl−/HCO3− exchangers but how this transport is regulated is not currently known. NHE3 (Slc9a3), an apical Na+/H+ exchanger, is an established target for regulation of electroneutral NaCl absorption working in concert with Cl−/HCO3− exchangers. To test whether NHE3 could be involved in regulation of intestinal oxalate transport and renal oxalate handling we compared urinary oxalate excretion rates and intestinal transepithelial fluxes of 14C‐oxalate and 22Na+ between NHE3 KO and wild‐type (WT) mice. NHE3 KO kidneys had lower creatinine clearance suggesting reduced GFR, but urinary oxalate excretion rates (µmol/24 h) were similar compared to the WT but doubled when expressed as a ratio of creatinine. Intestinal transepithelial fluxes of 14C‐oxalate and 22Na+ were measured in the distal ileum, cecum, and distal colon. The absence of NHE3 did not affect basal net transport rates of oxalate or sodium across any intestinal section examined. Stimulation of intracellular cAMP with forskolin (FSK) and 3‐isobutyl‐1‐methylxanthine (IBMX) led to an increase in net oxalate secretion in the WT distal ileum and cecum and inhibition of sodium absorption in the cecum and distal colon. In NHE3 KO cecum, cAMP stimulation of oxalate secretion was impaired suggesting the possibility of a role for NHE3 in this process. Although, there is little evidence for a role of NHE3 in basal intestinal oxalate fluxes, NHE3 may be important for cAMP stimulation of oxalate in the cecum and for renal handling of oxalate.
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Affiliation(s)
- Christine E Stephens
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Jonathan M Whittamore
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Marguerite Hatch
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
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17
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Yu Q. Slc26a3 (DRA) in the Gut: Expression, Function, Regulation, Role in Infectious Diarrhea and Inflammatory Bowel Disease. Inflamm Bowel Dis 2021; 27:575-584. [PMID: 32989468 DOI: 10.1093/ibd/izaa256] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND The transport of transepithelial Cl- and HCO3- is crucial for the function of the intestinal epithelium and maintains the acid-based homeostasis. Slc26a3 (DRA), as a key chloride-bicarbonate exchanger protein in the intestinal epithelial luminal membrane, participates in the electroneutral NaCl absorption of intestine, together with Na+/H+ exchangers. Increasing recent evidence supports the essential role of decreased DRA function or expression in infectious diarrhea and inflammatory bowel disease (IBD). METHOD In this review, we give an overview of the current knowledge of Slc26a3, including its cloning and expression, function, roles in infectious diarrhea and IBD, and mechanisms of actions. A better understanding of the physiological and pathophysiological relevance of Slc26a3 in infectious diarrhea and IBD may reveal novel targets for future therapy. CONCLUSION Understanding the physiological function, regulatory interactions, and the potential mechanisms of Slc26a3 in the pathophysiology of infectious diarrhea and IBD will define novel therapeutic approaches in future.
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Affiliation(s)
- Qin Yu
- Department of Gastroenterology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan City, China
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18
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Hayashi H, Nagai H, Ohba KI, Soleimani M, Suzuki Y. Segmental differences in Slc26a3-dependent Cl - absorption and HCO 3- secretion in the mouse large intestine in vitro in Ussing chambers. J Physiol Sci 2021; 71:5. [PMID: 33514305 PMCID: PMC10717946 DOI: 10.1186/s12576-020-00784-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 11/19/2020] [Indexed: 12/12/2022]
Abstract
The anion exchanger slc26a3 (DRA), which is mutated in congenital chloride-losing diarrhea, is expressed in the apical membrane of the cecum and middle-distal colon but not in the proximal colon of rodent large intestines. To elucidate the functional roles of DRA, we measured unidirectional 36Cl- and 22Na+ fluxes and HCO3- secretion in vitro in each of these segments using DRA-KO mice. Robust Cl- absorption, which was largely abolished after DRA deficiency, was present in the cecum and middle-distal colon but absent in the proximal colon. Na+ absorption was present in all three segments in both the control and DRA-KO mice. The luminal-Cl--dependent HCO3- secretions in the cecum and middle-distal colon were abolished in the DRA-KO mice. In conclusion, DRA mediates Cl- absorption and HCO3- secretion in the mouse cecum and middle-distal colon, and may have roles in H2O absorption and luminal acid/base regulation in these segments.
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Affiliation(s)
- Hisayoshi Hayashi
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Hiroki Nagai
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Kou-Ichiro Ohba
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Manoocher Soleimani
- Department of Medicine, University of Cincinnati, Cincinnati, OH, 45267, USA
| | - Yuichi Suzuki
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan.
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19
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Exploring the impact of intestinal ion transport on the gut microbiota. Comput Struct Biotechnol J 2020; 19:134-144. [PMID: 33425246 PMCID: PMC7773683 DOI: 10.1016/j.csbj.2020.12.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 12/08/2020] [Accepted: 12/09/2020] [Indexed: 12/12/2022] Open
Abstract
The gut microbiota and the host are intimately connected. The host physiology dictates the intestinal environment through regulation of pH, ion concentration, mucus production, etc., all of which exerts a selective pressure on the gut microbiota. Since different regions of the gastrointestinal tract are characterized by their own physicochemical conditions, distinct microbial communities are present in these locations. While it is widely accepted that the intestinal microbiome influences the host (tight junctions, cytokine/immune responses, diarrhea, etc.), the reciprocal interaction of the host on the microbiome is under-explored. This review aims to address these gaps in knowledge by focusing on how the host intestinal ion transport influences the luminal environment and thereby modulates the gut microbiota composition.
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Key Words
- CFTR
- CFTR, cystic fibrosis transmembrane regulator
- ClC, chloride channel
- DRA
- DRA, down-regulated in adenoma
- ENaC, epithelial Na+ channel
- GI, gastrointestinal
- GLUT2
- GLUT2, glucose transporter 2
- Gastrointestinal
- Ion transport
- Microbiome
- Microbiota
- NHE2
- NHE2, sodium-hydrogen exchanger isoform 2
- NHE3
- NHE3, sodium-hydrogen exchanger isoform 3
- NKCC1, Na+-K+-2Cl− co-transporter
- OTUs, operational taxonomic units
- SGLT1, sodium glucose co-transporter 1
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The anion exchanger PAT-1 (Slc26a6) does not participate in oxalate or chloride transport by mouse large intestine. Pflugers Arch 2020; 473:95-106. [PMID: 33205229 DOI: 10.1007/s00424-020-02495-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 10/23/2020] [Accepted: 11/10/2020] [Indexed: 01/20/2023]
Abstract
The membrane-bound transport proteins responsible for oxalate secretion across the large intestine remain unidentified. The apical chloride/bicarbonate (Cl-/HCO3-) exchanger encoded by Slc26a6, known as PAT-1 (putative anion transporter 1), is a potential candidate. In the small intestine, PAT-1 makes a major contribution to oxalate secretion but whether this role extends into the large intestine has not been directly tested. Using the PAT-1 knockout (KO) mouse, we compared the unidirectional absorptive ([Formula: see text]) and secretory ([Formula: see text]) flux of oxalate and Cl- across cecum, proximal colon, and distal colon from wild-type (WT) and KO mice in vitro. We also utilized the non-specific inhibitor DIDS (4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid) to confirm a role for PAT-1 in WT large intestine and (in KO tissues) highlight any other apical anion exchangers involved. Under symmetrical, short-circuit conditions the cecum and proximal colon did not transport oxalate on a net basis, whereas the distal colon supported net secretion. We found no evidence for the participation of PAT-1, or indeed any other DIDS-sensitive transport mechanism, in oxalate or Cl- by the large intestine. Most unexpectedly, mucosal DIDS concurrently stimulated [Formula: see text] and [Formula: see text] by 25-68% across each segment without impacting net transport. For the colon, these changes were directly proportional to increased transepithelial conductance suggesting this response was the result of bidirectional paracellular flux. In conclusion, PAT-1 does not contribute to oxalate or Cl- transport by the large intestine, and we urge caution when using DIDS with mouse colonic epithelium.
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21
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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: 4.2] [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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22
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Zhang M, Li T, Zhu J, Tuo B, Liu X. Physiological and pathophysiological role of ion channels and transporters in the colorectum and colorectal cancer. J Cell Mol Med 2020; 24:9486-9494. [PMID: 32662230 PMCID: PMC7520301 DOI: 10.1111/jcmm.15600] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/16/2020] [Accepted: 06/18/2020] [Indexed: 12/24/2022] Open
Abstract
The incidence of colorectal cancer has increased annually, and the pathogenesis of this disease requires further investigation. In normal colorectal tissues, ion channels and transporters maintain the water‐electrolyte balance and acid/base homeostasis. However, dysfunction of these ion channels and transporters leads to the development and progression of colorectal cancer. Therefore, this review focuses on the progress in understanding the roles of ion channels and transporters in the colorectum and in colorectal cancer, including aquaporins (AQPs), Cl− channels, Cl−/HCO3‐ exchangers, Na+/HCO3‐ transporters and Na+/H+ exchangers. The goal of this review is to promote the identification of new targets for the treatment and prognosis of colorectal cancer.
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Affiliation(s)
- Minglin Zhang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Taolang Li
- Department of Thyroid and Breast Surgery, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Jiaxing Zhu
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Xuemei Liu
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
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23
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Kurteva E, Lindley KJ, Hill SM, Köglmeier J. Mucosal Abnormalities in Children With Congenital Chloride Diarrhea-An Underestimated Phenotypic Feature? Front Pediatr 2020; 8:365. [PMID: 32850522 PMCID: PMC7403178 DOI: 10.3389/fped.2020.00365] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 06/01/2020] [Indexed: 01/12/2023] Open
Abstract
Objectives and Study: Congenital chloride diarrhea (CCD) is a rare, autosomal recessive disorder caused by mutations in the SLC26A3 gene encoding a transmembrane chloride/bicarbonate ion exchanger mainly expressed in the apical brush border of the ileal and colonic epithelium. Lifelong, secretory, chloride-rich diarrhea and hypochloremic, hypokalemic metabolic alkalosis are characteristic. Histological evidence of bowel inflammation is not typically described in CCD and has only been reported in a few patients. Methods: We report four cases of CCD who received adequate resuscitation with appropriate replacement of their fecal salt and water losses. Three had associated inflammatory bowel changes at endoscopy. The index case of CCD who developed frankly bloodstained diarrhea aged 7 months was found to have histologically confirmed colitis at endoscopy. An electronic search of the hospital database to identify all patients with confirmed CCD was performed. A further three children underwent de novo diagnostic evaluation and treatment. A retrospective case note review was undertaken to determine the incidence and subtype of inflammatory bowel disease (IBD) by clinical, endoscopic, and histological means. Results: Four children with genetically confirmed CCD were identified, two being female. The first girl had a granulomatous colitis with ulceration. She went into remission with a combination of steroids and azathioprine. Immunosuppression was subsequently discontinued without a further flare of colitis. A second girl was found to have patchy inflammatory changes in the small bowel and focal active colitis. A third patient, a boy, demonstrated mild inflammatory changes in the small bowel with apoptotic debris and mild inflammation in the colon. A fourth patient did not develop intestinal inflammation. Conclusion: Our case series highlights the potential association of CCD with panenteric inflammation. While our cohort was small, CCD is rare and three out of four children referred to our tertiary referral center were affected. While early diagnosis and adequate salt replacement therapy are crucial in CCD management, the clinician should also be aware of bowel inflammation as a potential cause of failure of CCD therapy to control bowel symptomatology. Further insight is needed to understand the underlying patho-mechanism giving rise to bowel inflammation in this group.
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Affiliation(s)
- Elena Kurteva
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Keith J Lindley
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Susan M Hill
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Jutta Köglmeier
- Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
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24
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Chen Y, Dinges MM, Green A, Cramer SE, Larive CK, Lytle C. Absorptive transport of amino acids by the rat colon. Am J Physiol Gastrointest Liver Physiol 2020; 318:G189-G202. [PMID: 31760764 PMCID: PMC6985843 DOI: 10.1152/ajpgi.00277.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The capacity of the colon to absorb microbially produced amino acids (AAs) and the underlying mechanisms of AA transport are incompletely defined. We measured the profile of 16 fecal AAs along the rat ceco-colonic axis and compared unidirectional absorptive AA fluxes across mucosal tissues isolated from the rat jejunum, cecum, and proximal colon using an Ussing chamber approach, in conjunction with 1H-NMR and ultra-performance liquid chromatography-mass spectrometry chemical analyses. Passage of stool from cecum to midcolon was associated with segment-specific changes in fecal AA composition and a decrease in total AA content. Simultaneous measurement of up to 16 AA fluxes under native luminal conditions, with correction for endogenous AA release, demonstrated absorptive transfer of AAs across the cecum and proximal colon at rates comparable (30-80%) to those across the jejunum, with significant Na+-dependent and H+-stimulated components. Expression profiling of 30 major AA transporter genes by quantitative PCR revealed comparatively high levels of transcripts for 20 AA transporters in the cecum and/or colon, with the levels of 12 exceeding those in the small intestine. Our results suggest a more detailed model of major apical and basolateral AA transporters in rat colonocytes and provide evidence for a previously unappreciated transfer of AAs across the colonic epithelium that could link the prodigious metabolic capacities of the luminal microbiota, the colonocytes, and the body tissues.NEW & NOTEWORTHY This study provides evidence for a previously unappreciated transfer of microbially generated amino acids across the colonic epithelium under physiological conditions that could link the prodigious metabolic capacities of the luminal microbiota, the colonocytes, and the body tissues. The segment-specific expression of at least 20 amino acid transporter genes along the colon provides a detailed mechanistic basis for uniport, heteroexchange, Na+-cotransport, and H+-cotransport components of colonic amino acid absorption.
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Affiliation(s)
- Yuxin Chen
- 1Division of Biomedical Sciences, School of Medicine, University of California, Riverside, California
| | - Meredith M. Dinges
- 2Department of Chemistry, University of California, Riverside, California
| | - Andrew Green
- 2Department of Chemistry, University of California, Riverside, California
| | - Scott E. Cramer
- 1Division of Biomedical Sciences, School of Medicine, University of California, Riverside, California
| | - Cynthia K. Larive
- 2Department of Chemistry, University of California, Riverside, California
| | - Christian Lytle
- 1Division of Biomedical Sciences, School of Medicine, University of California, Riverside, California
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25
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Lee S, Cil O, Haggie PM, Verkman AS. 4,8-Dimethylcoumarin Inhibitors of Intestinal Anion Exchanger slc26a3 (Downregulated in Adenoma) for Anti-Absorptive Therapy of Constipation. J Med Chem 2019; 62:8330-8337. [PMID: 31389695 PMCID: PMC7034394 DOI: 10.1021/acs.jmedchem.9b01192] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The chloride/bicarbonate exchanger SLC26A3 (downregulated in adenoma) is expressed mainly in colonic epithelium, where it dehydrates the stool by facilitating the final step of chloride and fluid absorption. SLC26A3 inhibition has predicted efficacy in various types of constipation including that associated with cystic fibrosis. We previously identified, by high-throughput screening, 4,8-dimethylcoumarin inhibitors of murine slc26a3 with IC50 down to ∼150 nM. Here, we synthesized a focused library of forty-three 4,8-dimethylcoumarin analogues. Structure-activity studies revealed the requirement of 4,8-dimethylcoumarin-3-acetic acid for activity. The most potent inhibitors were produced by replacements at C7, including 3-iodo- (4az) and 3-trifluoromethyl- (4be), with IC50 of 40 and 25 nM, respectively. Pharmacokinetics in mice showed predicted therapeutic concentrations of 4az for >72 h following a single 10 mg/kg oral dose. 4az at 10 mg/kg fully normalized stool water content in a loperamide-induced mouse model of constipation. The favorable inhibition potency, selectivity within the SLC26 family, and pharmacological properties of 4az support its further preclinical development.
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Affiliation(s)
- Sujin Lee
- Department of Medicine, University of California, San Francisco, San Francisco, California 94143-0521, United States
| | - Onur Cil
- Department of Medicine, University of California, San Francisco, San Francisco, California 94143-0521, United States
- Department of Pediatrics, University of California, San Francisco, San Francisco, California 94143-0521, United States
| | - Peter M. Haggie
- Department of Medicine, University of California, San Francisco, San Francisco, California 94143-0521, United States
| | - Alan S. Verkman
- Department of Medicine, University of California, San Francisco, San Francisco, California 94143-0521, United States
- Department of Physiology, University of California, San Francisco, San Francisco, California 94143-0521, United States
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26
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Rao MC. Physiology of Electrolyte Transport in the Gut: Implications for Disease. Compr Physiol 2019; 9:947-1023. [PMID: 31187895 DOI: 10.1002/cphy.c180011] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We now have an increased understanding of the genetics, cell biology, and physiology of electrolyte transport processes in the mammalian intestine, due to the availability of sophisticated methodologies ranging from genome wide association studies to CRISPR-CAS technology, stem cell-derived organoids, 3D microscopy, electron cryomicroscopy, single cell RNA sequencing, transgenic methodologies, and tools to manipulate cellular processes at a molecular level. This knowledge has simultaneously underscored the complexity of biological systems and the interdependence of multiple regulatory systems. In addition to the plethora of mammalian neurohumoral factors and their cross talk, advances in pyrosequencing and metagenomic analyses have highlighted the relevance of the microbiome to intestinal regulation. This article provides an overview of our current understanding of electrolyte transport processes in the small and large intestine, their regulation in health and how dysregulation at multiple levels can result in disease. Intestinal electrolyte transport is a balance of ion secretory and ion absorptive processes, all exquisitely dependent on the basolateral Na+ /K+ ATPase; when this balance goes awry, it can result in diarrhea or in constipation. The key transporters involved in secretion are the apical membrane Cl- channels and the basolateral Na+ -K+ -2Cl- cotransporter, NKCC1 and K+ channels. Absorption chiefly involves apical membrane Na+ /H+ exchangers and Cl- /HCO3 - exchangers in the small intestine and proximal colon and Na+ channels in the distal colon. Key examples of our current understanding of infectious, inflammatory, and genetic diarrheal diseases and of constipation are provided. © 2019 American Physiological Society. Compr Physiol 9:947-1023, 2019.
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Affiliation(s)
- Mrinalini C Rao
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois, USA
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27
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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: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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28
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King SJ, McCole DF. Epithelial-microbial diplomacy: escalating border tensions drive inflammation in inflammatory bowel disease. Intest Res 2019; 17:177-191. [PMID: 30836737 PMCID: PMC6505084 DOI: 10.5217/ir.2018.00170] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 02/01/2019] [Indexed: 02/07/2023] Open
Abstract
Inflammatory bowel diseases (IBD) are chronic conditions of the gastrointestinal tract-the main site of host-microbial interaction in the body. Development of IBD is not due to a single event but rather is a multifactorial process where a patient’s genetic background, behavioral habits, and environmental exposures contribute to disease pathogenesis. IBD patients exhibit alterations to gut bacterial populations “dysbiosis” due to the inflammatory microenvironment, however whether this alteration of the gut microbiota precedes inflammation has not been confirmed. Emerging evidence has highlighted the important role of gut microbes in developing measured immune responses and modulating other host responses such as metabolism. Much of the work on the gut microbiota has been correlative and there is an increasing need to understand the intimate relationship between host and microbe. In this review, we highlight how commensal and pathogenic bacteria interact with host intestinal epithelial cells and explore how altered microenvironments impact these connections.
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Affiliation(s)
- Stephanie J King
- Division of Biomedical Sciences, University of California, Riverside, CA, USA
| | - Declan F McCole
- Division of Biomedical Sciences, University of California, Riverside, CA, USA
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29
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Stephens CE, Whittamore JM, Hatch M. 125 Iodide as a surrogate tracer for epithelial chloride transport by the mouse large intestine in vitro. Exp Physiol 2019; 104:334-344. [PMID: 30615234 PMCID: PMC6397055 DOI: 10.1113/ep087445] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/02/2019] [Indexed: 12/25/2022]
Abstract
NEW FINDINGS What is the central question of this study? The tracer 36 Cl- , currently used to measure transepithelial Cl- fluxes, has become prohibitively expensive, threatening its future use. 125 Iodide, previously validated alongside 36 Cl- as a tracer of Cl- efflux by cells, has not been tested as a surrogate for 36 Cl- across epithelia. What is the main finding and its importance? We demonstrate that 125 I- can serve as an inexpensive replacement for measuring Cl- transport across mouse large intestine, tracking Cl- transport in response to cAMP stimulation (inducing Cl- secretion) in the presence and absence of the main gastrointestinal Cl- -HCO3- exchanger, DRA. ABSTRACT Chloride transport is important for driving fluid secretion and absorption by the large intestine, with dysregulation resulting in diarrhoea-associated pathologies. The radioisotope 36 Cl- has long been used as a tracer to measure epithelial Cl- transport but is prohibitively expensive. 125 Iodide has been used as an alternative to 36 Cl- in some transport assays but has never been validated as an alternative for tracing bidirectional transepithelial Cl- fluxes. The goal of this study was to validate 125 I- as an alternative to 36 Cl- for measurement of Cl- transport by the intestine. Simultaneous fluxes of 36 Cl- and 125 I- were measured across the mouse caecum and distal colon. Net Cl- secretion was induced by the stimulation of cAMP with a cocktail of forskolin (FSK) and 3-isobutyl-1-methylxanthine (IBMX). Unidirectional fluxes of 125 I- correlated well with 36 Cl- fluxes after cAMP-induced net Cl- secretion, occurring predominantly through a reduction in the absorptive mucosal-to-serosal Cl- flux rather than by stimulation of the secretory serosal-to-mucosal Cl- flux. Correlations between 125 I- fluxes and 36 Cl- fluxes were maintained in epithelia from mice lacking DRA (Slc26a3), the main Cl- -HCO3- exchanger responsible for Cl- absorption by the large intestine. Lower rates of Cl- and I- absorption in the DRA knockout intestine suggest that DRA might have a previously unrecognized role in iodide uptake. This study validates that 125 I- traces transepithelial Cl- fluxes across the mouse large intestine, provides insights into the mechanism of net Cl- secretion and suggests that DRA might be involved in intestinal iodide absorption.
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Affiliation(s)
- Christine E Stephens
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Jonathan M Whittamore
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Marguerite Hatch
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA
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30
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Inagaki A, Hayashi M, Andharia N, Matsuda H. Involvement of butyrate in electrogenic K + secretion in rat rectal colon. Pflugers Arch 2018; 471:313-327. [PMID: 30250967 PMCID: PMC6334752 DOI: 10.1007/s00424-018-2208-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 08/22/2018] [Accepted: 09/13/2018] [Indexed: 12/27/2022]
Abstract
Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, are synthesized from dietary carbohydrates by colonic bacterial fermentation. These SCFAs supply energy, suppress cancer, and affect ion transport. However, their roles in ion transport and regulation in the intracellular environment remain unknown. In order to elucidate the roles of SCFAs, we measured short-circuit currents (ISC) and performed RT-PCR and immunohistochemical analyses of ion transporters in rat rectal colon. The application of 30 mM butyrate shifted ISC in a negative direction, but did not attenuate the activity of epithelial Na+ channels (ENaC). The application of bumetanide, a Na+-K+-2Cl− cotransporter inhibitor, to the basolateral side reduced the negative ISC shift induced by butyrate. The application of XE991, a KCNQ-type K+ channel inhibitor, to the apical side decreased the ISC shift induced by butyrate in a dose-dependent manner. The ISC shift was independent of HCO3− and insensitive to ibuprofen, an SMCT1 inhibitor. The mucosa from rat rectal colon expressed mRNAs of H+-coupled monocarboxylate transporters (MCT1, MCT4, and MCT5, also referred to as SLC16A1, SLC16A3, and SLC16A4, respectively). RT-PCR and immunofluorescence analyses demonstrated that KCNQ2 and KCNQ4 localized to the apical membrane of surface cells in rat rectal colon. These results indicate that butyrate, which may be transported by H+-coupled monocarboxylate transporters, activates K+ secretion through KCNQ-type K+ channels on the apical membrane in rat rectal colon. KCNQ-type K+ channels may play a role in intestinal secretion and defense mechanisms in the gastrointestinal tract.
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Affiliation(s)
- Akihiro Inagaki
- Medical Research Project, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto, Tokushima, 770-8503, Japan.
| | - Mikio Hayashi
- Department of Physiology, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, 573-1010, Japan
| | - Naaz Andharia
- Department of Physiology, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, 573-1010, Japan
| | - Hiroko Matsuda
- Department of Physiology, Kansai Medical University, 2-5-1 Shinmachi, Hirakata, 573-1010, Japan
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31
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Haggie PM, Cil O, Lee S, Tan JA, Rivera AA, Phuan PW, Verkman AS. SLC26A3 inhibitor identified in small molecule screen blocks colonic fluid absorption and reduces constipation. JCI Insight 2018; 3:121370. [PMID: 30046015 DOI: 10.1172/jci.insight.121370] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/12/2018] [Indexed: 11/17/2022] Open
Abstract
SLC26A3 (downregulated in adenoma; DRA) is a Cl-/anion exchanger expressed in the luminal membrane of intestinal epithelial cells, where it facilitates electroneutral NaCl absorption. SLC26A3 loss of function in humans or mice causes chloride-losing diarrhea. Here, we identified slc26a3 inhibitors in a screen of 50,000 synthetic small molecules done in Fischer rat thyroid (FRT) cells coexpressing slc26a3 and a genetically encoded halide sensor. Structure-activity relationship studies were done on the most potent inhibitor classes identified in the screen: 4,8-dimethylcoumarins and acetamide-thioimidazoles. The dimethylcoumarin DRAinh-A250 fully and reversibly inhibited slc26a3-mediated Cl- exchange with HCO3-, I-, and thiocyanate (SCN-), with an IC50 of ~0.2 μM. DRAinh-A250 did not inhibit the homologous anion exchangers slc26a4 (pendrin) or slc26a6 (PAT-1), nor did it alter activity of other related proteins or intestinal ion channels. In mice, intraluminal DRAinh-A250 blocked fluid absorption in closed colonic loops but not in jejunal loops, while the NHE3 (SLC9A3) inhibitor tenapanor blocked absorption only in the jejunum. Oral DRAinh-A250 and tenapanor comparably reduced signs of constipation in loperamide-treated mice, with additive effects found on coadministration. DRAinh-A250 was also effective in loperamide-treated cystic fibrosis mice. These studies support a major role of slc26a3 in colonic fluid absorption and suggest the therapeutic utility of SLC26A3 inhibition in constipation.
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Affiliation(s)
| | - Onur Cil
- Department of Medicine.,Department of Pediatrics, and
| | | | | | | | | | - Alan S Verkman
- Department of Medicine.,Department of Physiology, UCSF, San Francisco, California, USA
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32
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SLC26A3 (DRA) prevents TNF-alpha-induced barrier dysfunction and dextran sulfate sodium-induced acute colitis. J Transl Med 2018; 98:462-476. [PMID: 29330471 DOI: 10.1038/s41374-017-0005-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 11/08/2017] [Accepted: 11/15/2017] [Indexed: 12/24/2022] Open
Abstract
SLC26A3 encodes a Cl-/HCO3- ion transporter that is also known as downregulated in adenoma (DRA) and is involved in HCO3-/mucus formation. The role of DRA in the epithelial barrier has not been previously established. In this study, we investigated the in vivo and in vitro mechanisms of DRA in the colon epithelial barrier. Immunofluorescence (IF) and co-immunoprecipitation (co-IP) studies reveal that DRA binds directly to tight junction (TJ) proteins and affects the expression of TJ proteins in polarized Caco-2BBe cells. Similarly, DRA colocalizes with ZO-1 in the intestinal epithelium. Knockdown or overexpression of DRA leads to alterations in TJ proteins and epithelial permeability. In addition, TNF-α treatment downregulates DRA by activating NF-кB and subsequently affecting intestinal epithelial barrier integrity. Furthermore, overexpression of DRA partly reverses the TNF-α-induced damage by stabilizing TJ proteins. Neutralization of TNF-α in dextran sulfate sodium (DSS)-induced colitis mice demonstrates improved the outcomes, and the therapeutic effect of the TNF-α neutralizing mAb is mediated in part by the preservation of DRA expression. These data suggest that DRA may be one of the therapeutic targets of TNF-α. Moreover, DRA delivered by adenovirus vector significantly prevents the exacerbation of colitis and improves epithelial barrier function by promoting the recovery of TJ proteins in DSS-treated mice. In conclusion, DRA plays a role in protecting the epithelial barrier and may be a therapeutic target in gut homeostasis.
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33
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Xu H, Ghishan FK, Kiela PR. SLC9 Gene Family: Function, Expression, and Regulation. Compr Physiol 2018; 8:555-583. [PMID: 29687889 DOI: 10.1002/cphy.c170027] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The Slc9 family of Na+ /H+ exchangers (NHEs) plays a critical role in electroneutral exchange of Na+ and H+ in the mammalian intestine as well as other absorptive and secretory epithelia of digestive organs. These transport proteins contribute to the transepithelial Na+ and water absorption, intracellular pH and cellular volume regulation as well as the electrolyte, acid-base, and fluid volume homeostasis at the systemic level. They also influence the function of other membrane transport mechanisms, affect cellular proliferation and apoptosis as well as cell migration, adherence to the extracellular matrix, and tissue repair. Additionally, they modulate the extracellular milieu to facilitate other nutrient absorption and to regulate the intestinal microbial microenvironment. Na+ /H+ exchange is inhibited in selected gastrointestinal diseases, either by intrinsic factors (e.g., bile acids, inflammatory mediators) or infectious agents and associated bacterial toxins. Disrupted NHE activity may contribute not only to local and systemic electrolyte imbalance but also to the disease severity via multiple mechanisms. In this review, we describe the cation proton antiporter superfamily of Na+ /H+ exchangers with a particular emphasis on the eight SLC9A isoforms found in the digestive tract, followed by a more integrative description in their roles in each of the digestive organs. We discuss regulatory mechanisms that determine the function of Na+ /H+ exchangers as pertinent to the digestive tract, their regulation in pathological states of the digestive organs, and reciprocally, the contribution of dysregulated Na+ /H+ exchange to the disease pathogenesis and progression. © 2018 American Physiological Society. Compr Physiol 8:555-583, 2018.
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Affiliation(s)
- Hua Xu
- Department of Pediatrics, Steele Children's Research Center, University of Arizona, Tucson, Arizona, USA
| | - Fayez K Ghishan
- Department of Pediatrics, Steele Children's Research Center, University of Arizona, Tucson, Arizona, USA
| | - Pawel R Kiela
- Department of Pediatrics, Steele Children's Research Center, University of Arizona, Tucson, Arizona, USA.,Department of Immunobiology, University of Arizona, Tucson, Arizona, USA
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34
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Dinges MM, Lytle C, Larive CK. 1H NMR-Based Identification of Intestinally Absorbed Metabolites by Ussing Chamber Analysis of the Rat Cecum. Anal Chem 2018; 90:4196-4202. [PMID: 29474787 DOI: 10.1021/acs.analchem.8b00393] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The large intestine (cecum and colon) is a complex biochemical factory of vital importance to human health. It plays a major role in digestion and absorption by salvaging nutrients from polysaccharides via fermentation initiated by the bacteria that comprise the gut microbiome. We hypothesize that the intestinal epithelium absorbs a limited number of luminal metabolites with bioactive potential while actively excluding those with toxic effects. To explore this concept, we combined 1H NMR detection with Ussing chamber measurements of absorptive transport by rat cecum. Numerous metabolites transported across the epithelium can be measured simultaneously by 1H NMR, a universal detector of organic compounds, alleviating the need for fluorescent or radiolabeled compounds. Our results demonstrate the utility of this approach to delineate the repertoire of fecal solutes that are selectively absorbed by the cecum and to determine their transport rates.
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Affiliation(s)
- Meredith M Dinges
- Department of Chemistry , University of California , Riverside , California 92521 , United States
| | - Christian Lytle
- School of Medicine , University of California , 900 University Avenue Riverside , California 92521 , United States
| | - Cynthia K Larive
- Department of Chemistry , University of California , Riverside , California 92521 , United States
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35
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Development and Characterization of a Human and Mouse Intestinal Epithelial Cell Monolayer Platform. Stem Cell Reports 2017; 9:1976-1990. [PMID: 29153987 PMCID: PMC5785676 DOI: 10.1016/j.stemcr.2017.10.013] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 10/13/2017] [Accepted: 10/15/2017] [Indexed: 12/13/2022] Open
Abstract
We describe the development and characterization of a mouse and human epithelial cell monolayer platform of the small and large intestines, with a broad range of potential applications including the discovery and development of minimally systemic drug candidates. Culture conditions for each intestinal segment were optimized by correlating monolayer global gene expression with the corresponding tissue segment. The monolayers polarized, formed tight junctions, and contained a diversity of intestinal epithelial cell lineages. Ion transport phenotypes of monolayers from the proximal and distal colon and small intestine matched the known and unique physiology of these intestinal segments. The cultures secreted serotonin, GLP-1, and FGF19 and upregulated the epithelial sodium channel in response to known biologically active agents, suggesting intact secretory and absorptive functions. A screen of over 2,000 pharmacologically active compounds for inhibition of potassium ion transport in the mouse distal colon cultures led to the identification of a tool compound. Epithelial cell monolayer growth conditions developed for all intestinal segments Monolayer gene expression is consistent with tissue from each intestinal segment Ion transport, secretory, and absorptive functions match intestinal physiology Compound screen identified inhibitor of mouse distal colon potassium transport
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36
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Jayawardena D, Anbazhagan AN, Guzman G, Dudeja PK, Onyuksel H. Vasoactive Intestinal Peptide Nanomedicine for the Management of Inflammatory Bowel Disease. Mol Pharm 2017; 14:3698-3708. [PMID: 28991483 DOI: 10.1021/acs.molpharmaceut.7b00452] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Inflammatory bowel disease (IBD) is a chronic relapsing disorder of the intestine, with increasing incidence worldwide. At present, the management of IBD is an unmet medical need due to the ineffectiveness of currently available drugs in treating all patients, and there is strong demand for novel therapeutics. In this regard, vasoactive intestinal peptide, a potent anti-inflammatory endogenous hormone, has shown promise in managing multiple immune disorders in animal models. However, when administered in the free form, VIP undergoes rapid degradation in vivo, and with continuous infusion, it causes severe dose limiting side effects. To overcome these barriers, we have developed a superior mode to deliver VIP in its native form, using sterically stabilized micelles (VIP-SSM). Our previous studies demonstrated that, VIP, when administered in SSM, prevented joint damage and inflammation in a mouse model of rheumatoid arthritis at a significantly lower dose than the free peptide, completely abrogating the serious side effect of hypotension associated with VIP. In the current study, we demonstrate the therapeutic benefit of VIP-SSM over free peptide in reversing severe colitis associated with IBD. First, we conducted preliminary studies with dextran sulfate sodium (DSS) induced colitis in mice, to determine the effectiveness of VIP administered on alternate days in reducing disease severity. Thereafter, a single intra peritoneal injection of VIP-SSM or the free peptide was used to determine its therapeutic effect on the reversal of colitis and associated diarrhea. The results demonstrated that when administered on alternate days, both VIP-SSM and VIP were capable of alleviating DSS colitis in mice. However, when administered as a single dose, in a therapeutic setting, VIP-SSM showed superior benefits compared to the free peptide in ameliorating colitis phenotype. Namely, the loss of solid fecal pellets and increased fluid accumulation in colon resulting from DSS insult was abrogated in VIP-SSM treated mice and not with free VIP. Furthermore, reduced protein and mRNA levels of the major chloride bicarbonate exchanger, down regulated in adenoma (DRA), seen with DSS was reversed with VIP-SSM, but not with the free peptide. Similarly, VIP-SSM treatment significantly reduced the elevated mRNA levels of pro-inflammatory cytokines and showed significant histologic recovery when compared to mice treated with free VIP. Therefore, these results demonstrated that as a single dose, the anti-inflammatory and antidiarrheal effects of VIP can be achieved effectively when administered as a nanomedicine. Therefore, we propose VIP-SSM to be developed as a potential therapeutic tool for treating ulcerative colitis, a type of IBD.
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Affiliation(s)
| | | | | | - Pradeep K Dudeja
- Jesse Brown VA Medical Center , Chicago Illinois 60612, United States
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Bumetanide increases Cl--dependent short-circuit current in late distal colon: Evidence for the presence of active electrogenic Cl- absorption. PLoS One 2017; 12:e0171045. [PMID: 28152000 PMCID: PMC5289505 DOI: 10.1371/journal.pone.0171045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/13/2017] [Indexed: 12/17/2022] Open
Abstract
Mammalian colonic epithelia consist of cells that are capable of both absorbing and secreting Cl-. The present studies employing Ussing chamber technique identified two opposing short-circuit current (Isc) responses to basolateral bumetanide in rat distal colon. Apart from the transepithelial Cl--secretory Isc in early distal colon that was inhibited by bumetanide, bumetanide also stimulated Isc in late distal colon that had not previously been identified. Since bumetanide inhibits basolateral Na+-K+-2Cl- cotransporter (NKCC) in crypt cells and basolateral K+-Cl- cotransporter (KCC) in surface epithelium, we proposed this stimulatory Isc could represent a KCC-mediated Cl- absorptive current. In support of this hypothesis, ion substitution experiments established Cl- dependency of this absorptive Isc and transport inhibitor studies demonstrated the involvement of an apical Cl- conductance. Current distribution and RNA sequencing analyses revealed that this Cl- absorptive Isc is closely associated with epithelial Na+ channel (ENaC) but is not dependent on ENaC activity. Thus, inhibition of ENaC by 10 μM amiloride or benzamil neither altered the direction nor its activity. Physiological studies suggested that this Cl- absorptive Isc senses dietary Cl- content; thus when dietary Cl- was low, Cl- absorptive Isc was up-regulated. In contrast, when dietary Cl- was increased, Cl- absorptive Isc was down-regulated. We conclude that an active Cl- extrusion mechanism exists in ENaC-expressing late distal colon and likely operates in parallel with ENaC to facilitate NaCl absorption.
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The role of intestinal oxalate transport in hyperoxaluria and the formation of kidney stones in animals and man. Urolithiasis 2016; 45:89-108. [PMID: 27913853 DOI: 10.1007/s00240-016-0952-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 11/22/2016] [Indexed: 12/26/2022]
Abstract
The intestine exerts a considerable influence over urinary oxalate in two ways, through the absorption of dietary oxalate and by serving as an adaptive extra-renal pathway for elimination of this waste metabolite. Knowledge of the mechanisms responsible for oxalate absorption and secretion by the intestine therefore have significant implications for understanding the etiology of hyperoxaluria, as well as offering potential targets for future treatment strategies for calcium oxalate kidney stone disease. In this review, we present the recent developments and advances in this area over the past 10 years, and put to the test some of the new ideas that have emerged during this time, using human and mouse models. A key focus for our discussion are the membrane-bound anion exchangers, belonging to the SLC26 gene family, some of which have been shown to participate in transcellular oxalate absorption and secretion. This has offered the opportunity to not only examine the roles of these specific transporters, revealing their importance to oxalate homeostasis, but to also probe the relative contributions made by the active transcellular and passive paracellular components of oxalate transport across the intestine. We also discuss some of the various physiological stimuli and signaling pathways which have been suggested to participate in the adaptation and regulation of intestinal oxalate transport. Finally, we offer an update on research into Oxalobacter formigenes, alongside recent investigations of other oxalate-degrading gut bacteria, in both laboratory animals and humans.
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Kumar A, Anbazhagan AN, Coffing H, Chatterjee I, Priyamvada S, Gujral T, Saksena S, Gill RK, Alrefai WA, Borthakur A, Dudeja PK. Lactobacillus acidophilus counteracts inhibition of NHE3 and DRA expression and alleviates diarrheal phenotype in mice infected with Citrobacter rodentium. Am J Physiol Gastrointest Liver Physiol 2016; 311:G817-G826. [PMID: 27634011 PMCID: PMC5130543 DOI: 10.1152/ajpgi.00173.2016] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 09/12/2016] [Indexed: 01/31/2023]
Abstract
Impaired absorption of electrolytes is a hallmark of diarrhea associated with inflammation or enteric infections. Intestinal epithelial luminal membrane NHE3 (Na+/H+ exchanger 3) and DRA (Down-Regulated in Adenoma; Cl-/HCO3- exchanger) play key roles in mediating electroneutral NaCl absorption. We have previously shown decreased NHE3 and DRA function in response to short-term infection with enteropathogenic E coli (EPEC), a diarrheal pathogen. Recent studies have also shown substantial downregulation of DRA expression in a diarrheal model of infection with Citrobacter rodentium, the mouse counterpart of EPEC. Since our previous studies showed that the probiotic Lactobacillus acidophilus (LA) increased DRA and NHE3 function and expression and conferred protective effects in experimental colitis, we sought to evaluate the efficacy of LA in counteracting NHE3 and DRA inhibition and ameliorating diarrhea in a model of C rodentium infection. FVB/N mice challenged with C rodentium [1 × 109 colony-forming units (CFU)] with or without administration of live LA (3 × 109 CFU) were assessed for NHE3 and DRA mRNA and protein expression, mRNA levels of carbonic anhydrase, diarrheal phenotype (assessed by colonic weight-to-length ratio), myeloperoxidase activity, and proinflammatory cytokines. LA counteracted C rodentium-induced inhibition of colonic DRA, NHE3, and carbonic anhydrase I and IV expression and attenuated diarrheal phenotype and MPO activity. Furthermore, LA completely blocked C rodentium induction of IL-1β, IFN-γ, and CXCL1 mRNA and C rodentium-induced STAT3 phosphorylation. In conclusion, our data provide mechanistic insights into antidiarrheal effects of LA in a model of infectious diarrhea and colitis.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Alip Borthakur
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago and Jesse Brown VA Medical Center, Chicago, Illinois
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40
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Roostaee A, Guezguez A, Beauséjour M, Simoneau A, Vachon PH, Levy E, Beaulieu JF. Histone deacetylase inhibition impairs normal intestinal cell proliferation and promotes specific gene expression. J Cell Biochem 2016; 116:2695-708. [PMID: 26129821 PMCID: PMC5014201 DOI: 10.1002/jcb.25274] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 06/25/2015] [Indexed: 12/19/2022]
Abstract
Mechanisms that maintain proliferation and delay cell differentiation in the intestinal crypt are not yet fully understood. We have previously shown the implication of histone methylation in the regulation of enterocytic differentiation. In this study, we investigated the role of histone deacetylation as an important epigenetic mechanism that controls proliferation and differentiation of intestinal cells using the histone deacetylase inhibitor suberanilohydroxamic acid (SAHA) on the proliferation and differentiation of human and mouse intestinal cells. Treatment of newly confluent Caco‐2/15 cells with SAHA resulted in growth arrest, increased histone acetylation and up‐regulation of the expression of intestine‐specific genes such as those encoding sucrase‐isomaltase, villin and the ion exchanger SLC26A3. Although SAHA has been recently used in clinical trials for cancer treatment, its effect on normal intestinal cells has not been documented. Analyses of small and large intestines of mice treated with SAHA revealed a repression of crypt cell proliferation and a higher expression of sucrase‐isomaltase in both segments compared to control mice. Expression of SLC26A3 was also significantly up‐regulated in the colons of mice after SAHA administration. Finally, SAHA was also found to strongly inhibit normal human intestinal crypt cell proliferation in vitro. These results demonstrate the important implication of epigenetic mechanisms such as histone acetylation/deacetylation in the regulation of normal intestinal cell fate and proliferation. J. Cell. Biochem. 116: 2695–2708, 2015. © 2015 The Authors. Journal of Cellular Biochemistry published by Wiley Periodicals, Inc.
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Affiliation(s)
- Alireza Roostaee
- Laboratory of Intestinal Physiopathology, Université de Sherbrooke, Sherbrooke, Québec, Canada, J1H 5N4.,Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada, J1H 5N4
| | - Amel Guezguez
- Laboratory of Intestinal Physiopathology, Université de Sherbrooke, Sherbrooke, Québec, Canada, J1H 5N4.,Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada, J1H 5N4
| | - Marco Beauséjour
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada, J1H 5N4
| | - Aline Simoneau
- Laboratory of Intestinal Physiopathology, Université de Sherbrooke, Sherbrooke, Québec, Canada, J1H 5N4
| | - Pierre H Vachon
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada, J1H 5N4
| | - Emile Levy
- Department of Nutrition, Université de Montréal, and Research Center, Sainte-Justine UHC, Montréal, Québec, Canada, H3T 1C5
| | - Jean-François Beaulieu
- Laboratory of Intestinal Physiopathology, Université de Sherbrooke, Sherbrooke, Québec, Canada, J1H 5N4.,Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada, J1H 5N4
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41
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Barrett KE. Endogenous and exogenous control of gastrointestinal epithelial function: building on the legacy of Bayliss and Starling. J Physiol 2016; 595:423-432. [PMID: 27284010 DOI: 10.1113/jp272227] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 04/12/2016] [Indexed: 12/21/2022] Open
Abstract
Transport of fluid and electrolytes in the intestine allows for appropriate adjustments in luminal fluidity while reclaiming water used in digesting and absorbing a meal, and is closely regulated. This article discusses various endogenous and exogenous mechanisms whereby transport is controlled in the gut, placing these in the context of the ideas about the neurohumoral control of alimentary physiology that were promulgated by William Bayliss and Ernest Starling. The article considers three themes. First, mechanisms that intrinsically regulate chloride secretion, centred on the epidermal growth factor receptor (EGFr), are discussed. These may be important in ensuring that excessive chloride secretion, with the accompanying loss of fluid, is not normally stimulated by intestinal distension as the meal passes through the gastrointestinal tract. Second, mechanisms whereby probiotic microorganisms can impart beneficial effects on the gut are described, with a focus on targets at the level of the epithelium. These findings imply that the commensal microbiota exert important influences on the epithelium in health and disease. Finally, mechanisms that lead to diarrhoea in patients infected with an invasive pathogen, Salmonella, are considered, based on recent studies in a novel mouse model. Diarrhoea is most likely attributable to reduced expression of absorptive transporters and may not require the influx of neutrophils that accompanies infection. Overall, the goal of the article is to highlight the many ways in which critical functions of the intestinal epithelium are regulated under physiological and pathophysiological conditions, and to suggest possible targets for new therapies for digestive disease states.
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Affiliation(s)
- Kim E Barrett
- Department of Medicine and Biomedical Sciences Ph.D. Program, School of Medicine, University of California, La Jolla, San Diego, CA, USA
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42
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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: 1.9] [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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Kaji I, Akiba Y, Said H, Narimatsu K, Kaunitz JD. Luminal 5-HT stimulates colonic bicarbonate secretion in rats. Br J Pharmacol 2015; 172:4655-70. [PMID: 26061462 DOI: 10.1111/bph.13216] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 04/16/2015] [Accepted: 05/09/2015] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND AND PURPOSE The bioactive monoamine 5-HT, implicated in the pathogenesis of functional gastrointestinal disorders, is abundantly synthesized and stored in rat proximal colonic mucosa and released to the gut lumen and subepithelial space. Despite much data regarding its expression and function, the effects of luminal 5-HT on colonic anion secretion have not been fully investigated. EXPERIMENTAL APPROACH We measured short-circuit current (Isc ) as an indicator of ion transport in mucosa-submucosa or mucosa-only preparations of rat proximal colon. Total CO2 output was measured in vitro and in vivo. Immunohistochemistry was performed to investigate the localization of 5-HT4 , NOS1 and NOS2. KEY RESULTS Luminal 5-HT gradually increased the amplitude and sustained the elevation of Isc . Luminal 5-HT-evoked ΔIsc was acetazolamide sensitive and HCO3 (-) dependent, consistent with cytosolic carbonic anhydrase-dependent electrogenic HCO3 (-) secretion, while not affected by tetrodotoxin (TTX), atropine or indomethacin. Pretreatment with the selective 5-HT4 antagonist GR113808, but not antagonists for 5-HT3 , 5-HT6 or 5-HT7 , inhibited luminal 5-HT-evoked ΔIsc . Furthermore, luminal cisapride and tegaserod increased Isc to the same extent as did 5-HT in the presence of indomethacin and TTX. Removal of the submucosa or pretreatment with NOS inhibitors enhanced luminal 5-HT-evoked ΔIsc , suggesting that NO synthesized in the submucosa suppresses mucosal anion secretion. NOS1 and NOS2 were immunostained in the submucosal neurons and glial cells respectively. Luminal 5-HT-evoked HCO3 (-) secretion was confirmed in vivo, inhibited by co-perfusion of GR113808, but not by ondansetron. CONCLUSIONS AND IMPLICATIONS A novel apical 5-HT4 -mediated HCO3 (-) secretory pathway and an NO-dependent inhibitory mechanism are present in the proximal colon. Luminal 5-HT-evoked HCO3 (-) secretion may be important for the maintenance of mucosal integrity by regulating luminal pH.
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Affiliation(s)
- I Kaji
- Department of Medicine, University of California, Los Angeles, CA, USA.,Brentwood Biomedical Research Institute, Los Angeles, CA, USA
| | - Y Akiba
- Department of Medicine, University of California, Los Angeles, CA, USA.,Brentwood Biomedical Research Institute, Los Angeles, CA, USA.,Greater Los Angeles Veterans Affairs Healthcare System, CA, USA
| | - H Said
- College of Letters and Sciences, University of California, Los Angeles, CA, USA
| | - K Narimatsu
- Department of Medicine, University of California, Los Angeles, CA, USA
| | - J D Kaunitz
- Department of Medicine, University of California, Los Angeles, CA, USA.,Department of Surgery, School of Medicine, University of California, Los Angeles, CA, USA.,Brentwood Biomedical Research Institute, Los Angeles, CA, USA.,Greater Los Angeles Veterans Affairs Healthcare System, CA, USA
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Priyamvada S, Anbazhagan AN, Gujral T, Borthakur A, Saksena S, Gill RK, Alrefai WA, Dudeja PK. All-trans-retinoic Acid Increases SLC26A3 DRA (Down-regulated in Adenoma) Expression in Intestinal Epithelial Cells via HNF-1β. J Biol Chem 2015; 290:15066-77. [PMID: 25887398 PMCID: PMC4463450 DOI: 10.1074/jbc.m114.566356] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 04/10/2015] [Indexed: 11/06/2022] Open
Abstract
All-trans-retinoic acid (ATRA) is an active vitamin A derivative known to modulate a number of physiological processes, including growth and development, differentiation, and gene transcription. The protective effect of ATRA in gut inflammation and diarrheal diseases has been documented. In this regard, down-regulated in adenoma (DRA, a key luminal membrane Cl(-) transporter involved in NaCl absorption) has been shown to be suppressed in intestinal inflammation. This suppression of DRA is associated with diarrheal phenotype. Therefore, current studies were undertaken to examine the effects of ATRA on DRA expression. DRA mRNA levels were significantly elevated (∼4-fold) in response to ATRA with induction starting as early as 8 h of incubation. Similarly, ATRA increased DRA protein expression by ∼50%. Furthermore, DRA promoter activity was significantly increased in response to ATRA indicating transcriptional activation. ATRA effects on DRA expression appeared to be mediated via the RAR-β receptor subtype, as ATRA remarkably induced RAR-β mRNA levels, whereas RAR-β knockdown substantially attenuated the ability of ATRA to increase DRA expression. Results obtained from agonist (CH-55) and antagonist (LE-135) studies further confirmed that ATRA exerts its effects through RAR-β. Furthermore, ATRA treatment resulted in a significant increase in HNF-1β mRNA levels. The ability of ATRA to induce DRA expression was inhibited in the presence of HNF-1β siRNA indicative of its involvement in ATRA-induced effects on DRA expression. In conclusion, ATRA may act as an antidiarrheal agent by increasing DRA expression via the RAR-β/HNF-1β-dependent pathway.
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Affiliation(s)
- Shubha Priyamvada
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Arivarasu N Anbazhagan
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Tarunmeet Gujral
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Alip Borthakur
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Seema Saksena
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Ravinder K Gill
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612
| | - Waddah A Alrefai
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612 From the Jesse Brown Veterans Affairs Medical Center
| | - Pradeep K Dudeja
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612 From the Jesse Brown Veterans Affairs Medical Center,
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45
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Tang L, Peng M, Liu L, Chang W, Binder HJ, Cheng SX. Calcium-sensing receptor stimulates Cl(-)- and SCFA-dependent but inhibits cAMP-dependent HCO3(-) secretion in colon. Am J Physiol Gastrointest Liver Physiol 2015; 308:G874-83. [PMID: 25792563 PMCID: PMC4437021 DOI: 10.1152/ajpgi.00341.2014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 03/10/2015] [Indexed: 02/07/2023]
Abstract
Colonic bicarbonate (HCO3(-)) secretion is a well-established physiological process that is closely linked to overall fluid and electrolyte movement in the mammalian colon. These present studies show that extracellular calcium-sensing receptor (CaSR), a fundamental mechanism for sensing and regulating ionic and nutrient compositions of extracellular milieu in the small and large intestine, regulates HCO3(-) secretion. Basal and induced HCO3(-) secretory responses to CaSR agonists were determined by pH stat techniques used in conjunction with short-circuit current measurements in mucosa from rat distal colon mounted in Ussing chambers. R568, a specific CaSR activator, stimulated lumen Cl(-)- and short-chain fatty acid (SCFA)-dependent HCO3(-) secretion but inhibited cyclic nucleotide-activated HCO3(-) secretion. Consequently, at physiological conditions (either at basal or during lumen acid challenge) when electroneutral Cl(-)/HCO3(-) and SCFA/HCO3(-) exchangers dominate, CaSR stimulates HCO3(-) secretion; in contrast, in experimental conditions that stimulate fluid and HCO3(-) secretion, e.g., when forskolin activates electrogenic cystic fibrosis transmembrane conductance regulator-mediated HCO3(-) conductance, CaSR activation inhibits HCO3(-) secretion. Corresponding changes in JHCO3 (μeq·h(-1)·cm(-2), absence vs. presence of R568) were 0.18 ± 0.03 vs. 0.31 ± 0.08 under basal nonstimulated conditions and 1.85 ± 0.23 vs. 0.45 ± 0.06 under forskolin-stimulated conditions. Similarly, activation of CaSR by R568 stimulated Cl(-)- and SCFA-dependent HCO3(-) secretion and inhibited cAMP-dependent HCO3(-) secretion in colon mucosa of wild-type mice; such effects were abolished in CaSR-null mice. These results suggest a new paradigm for regulation of intestinal ion transport in which HCO3(-) secretion may be fine-tuned by CaSR in accordance with nutrient availability and state of digestion and absorption. The ability of CaSR agonists to inhibit secretagogue-induced intestinal HCO3(-) secretion suggests that modulation of CaSR activity may provide a new therapeutic approach to correct HCO3(-) deficit and metabolic acidosis, a primary cause of morbidity and mortality in acute infectious diarrheal illnesses.
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Affiliation(s)
- Lieqi Tang
- 1Division of Gastroenterology, Nutrition and Hepatology, Department of Pediatrics, University of Florida, Gainesville, Florida;
| | - Minzhi Peng
- 1Division of Gastroenterology, Nutrition and Hepatology, Department of Pediatrics, University of Florida, Gainesville, Florida;
| | - Li Liu
- 2Department of Pediatrics, Guangzhou Women and Children's Medical Center, Guangzhou, Guangdong, People's Republic of China;
| | - Wenhan Chang
- 3Endocrine Research, VA Medical Center, University of California at San Francisco, San Francisco, California;
| | - Henry J. Binder
- 4Department of Internal Medicine, Yale University, New Haven, Connecticut
| | - Sam X. Cheng
- 1Division of Gastroenterology, Nutrition and Hepatology, Department of Pediatrics, University of Florida, Gainesville, Florida;
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46
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Whittamore JM, Frost SC, Hatch M. Effects of acid-base variables and the role of carbonic anhydrase on oxalate secretion by the mouse intestine in vitro. Physiol Rep 2015; 3:e12282. [PMID: 25716924 PMCID: PMC4393191 DOI: 10.14814/phy2.12282] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 12/06/2014] [Accepted: 12/30/2014] [Indexed: 12/15/2022] Open
Abstract
Hyperoxaluria is a major risk factor for calcium oxalate kidney stones and the intestine is recognized as an important extra-renal pathway for eliminating oxalate. The membrane-bound chloride/bicarbonate (Cl(-)/) exchangers are involved in the transcellular movement of oxalate, but little is understood about how they might be regulated. , CO2, and pH are established modulators of intestinal NaCl cotransport, involving Na(+)/H(+) and Cl(-)/ exchange, but their influence on oxalate transport is unknown. Measuring (14)C-oxalate and (36)Cl fluxes across isolated, short-circuited segments of the mouse distal ileum and distal colon we examined the role of these acid-base variables and carbonic anhydrase (CA) in oxalate and Cl(-) transport. In standard buffer both segments performed net oxalate secretion (and Cl(-) absorption), but only the colon, and the secretory pathway were responsive to and CO2. Ethoxzolamide abolished net oxalate secretion by the distal colon, and when used in tandem with an impermeant CA inhibitor, signaled an intracellular CA isozyme was required for secretion. There was a clear dependence on as their removal eliminated secretion, while at 42 mmol/L was also decreased and eradicated. Independent of pH, raising Pco2 from 28 to 64 mmHg acutely stimulated net oxalate secretion 41%. In summary, oxalate secretion by the distal colon was dependent on , CA and specifically modulated by CO2, whereas the ileum was remarkably unresponsive. These findings highlight the distinct segmental heterogeneity along the intestine, providing new insights into the oxalate transport mechanism and how it might be regulated.
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Affiliation(s)
- Jonathan M Whittamore
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of FloridaGainesville, Florida, USA
| | - Susan C Frost
- Department of Biochemistry and Molecular Biology, College of Medicine, University of FloridaGainesville, Florida, USA
| | - Marguerite Hatch
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of FloridaGainesville, Florida, USA
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Abstract
Technological advances in the large scale analysis of human genetics have generated profound insights into possible genetic contributions to chronic diseases including the inflammatory bowel diseases (IBDs), Crohn's disease and ulcerative colitis. To date, 163 distinct genetic risk loci have been associated with either Crohn's disease or ulcerative colitis, with a substantial degree of genetic overlap between these 2 conditions. Although many risk variants show a reproducible correlation with disease, individual gene associations only affect a subset of patients, and the functional contribution(s) of these risk variants to the onset of IBD is largely undetermined. Although studies in twins have demonstrated that the development of IBD is not mediated solely by genetic risk, it is nevertheless important to elucidate the functional consequences of risk variants for gene function in relevant cell types known to regulate key physiological processes that are compromised in IBD. This article will discuss IBD candidate genes that are known to be, or are suspected of being, involved in regulating the intestinal epithelial barrier and several of the physiological processes presided over by this dynamic and versatile layer of cells. This will include assembly and regulation of tight junctions, cell adhesion and polarity, mucus and glycoprotein regulation, bacterial sensing, membrane transport, epithelial differentiation, and restitution.
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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: 65] [Impact Index Per Article: 5.9] [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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MARCHELLETTA RONALDR, GAREAU MELANIEG, MCCOLE DECLANF, OKAMOTO SHARON, ROEL ELISE, KLINKENBERG RACHEL, GUINEY DONALDG, FIERER JOSHUA, BARRETT KIME. Altered expression and localization of ion transporters contribute to diarrhea in mice with Salmonella-induced enteritis. Gastroenterology 2013; 145:1358-1368.e1-4. [PMID: 24001788 PMCID: PMC3899031 DOI: 10.1053/j.gastro.2013.08.054] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 08/21/2013] [Accepted: 08/22/2013] [Indexed: 01/04/2023]
Abstract
BACKGROUND & AIMS Salmonella enterica serovar Typhimurium is an enteropathogen that causes self-limiting diarrhea in healthy individuals, but poses a significant health threat to vulnerable populations. Our understanding of the pathogenesis of Salmonella-induced diarrhea has been hampered by the lack of a suitable mouse model. After a dose of oral kanamycin, Salmonella-infected congenic BALB/c.D2(NrampG169) mice, which carry a wild-type Nramp1 gene, develop clear manifestations of diarrhea. We used this model to elucidate the pathophysiology of Salmonella-induced diarrhea. METHODS BALB /c.D2(NrampG169) mice were treated with kanamycin and then infected with wild-type or mutant Salmonella by oral gavage. Colon tissues were isolated and Ussing chambers, quantitative polymerase chain reaction, immunoblot, and confocal microscopy analyses were used to study function and expression of ion transporters and cell proliferation. RESULTS Studies with Ussing chambers demonstrated reduced basal and/or adenosine 3',5'-cyclic monophosphate-mediated electrogenic ion transport in infected colonic tissues, attributable to changes in chloride or sodium transport, depending on the segment studied. The effects of infection were mediated, at least in part, by effector proteins secreted by the bacterial Salmonella pathogenicity island 1- and Salmonella pathogenicity island-2-encoded virulence systems. Infected tissue showed reduced expression of the chloride-bicarbonate exchanger down-regulated in adenoma in surface colonic epithelial cells. Cystic fibrosis transmembrane conductance regulator was internalized in colonic crypt epithelial cells without a change in overall expression levels. Confocal analyses, densitometry, and quantitative polymerase chain reaction revealed that expression of epithelial sodium channel β was reduced in distal colons of Salmonella-infected mice. The changes in transporter expression, localization, and/or function were accompanied by crypt hyperplasia in Salmonella-infected mice. CONCLUSIONS Salmonella infection induces diarrhea by altering expression and/or function of transporters that mediate water absorption in the colon, likely reflecting the fact that epithelial cells have less time to differentiate into surface cells when proliferation rates are increased by infection.
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Affiliation(s)
- RONALD R. MARCHELLETTA
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California
| | - MELANIE G. GAREAU
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California
| | - DECLAN F. MCCOLE
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California
| | - SHARON OKAMOTO
- Department of Medicine, VA San Diego Medical Center, San Diego, California
| | - ELISE ROEL
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California
| | - RACHEL KLINKENBERG
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California
| | - DONALD G. GUINEY
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California
| | - JOSHUA FIERER
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California,Department of Medicine, VA San Diego Medical Center, San Diego, California
| | - KIM E. BARRETT
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, California
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Engevik MA, Aihara E, Montrose MH, Shull GE, Hassett DJ, Worrell RT. Loss of NHE3 alters gut microbiota composition and influences Bacteroides thetaiotaomicron growth. Am J Physiol Gastrointest Liver Physiol 2013; 305:G697-711. [PMID: 24072680 PMCID: PMC3840232 DOI: 10.1152/ajpgi.00184.2013] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Changes in the intestinal microbiota have been linked to diabetes, obesity, inflammatory bowel disease, and Clostridium difficile (C. difficile)-associated disease. Despite this, it remains unclear how the intestinal environment, set by ion transport, affects luminal and mucosa-associated bacterial composition. Na(+)/H(+)-exchanger isoform 3 (NHE3), a target of C. difficile toxin B, plays an integral role in intestinal Na(+) absorption. Thus the NHE3-deficient mouse model was chosen to examine the effect of pH and ion composition on bacterial growth. We hypothesized that ion transport-induced change in the intestinal environment would lead to alteration of the microbiota. Region-specific changes in ion composition and pH correlated with region-specific alteration of luminal and mucosal-associated bacteria with general decreases in Firmicutes and increases in Bacteroidetes members. Bacteroides thetaiotaomicron (B. thetaiotaomicron) increased in NHE3(-/-) terminal ileum and was examined in vitro to determine whether altered Na(+) was sufficient to affect growth. Increased in vitro growth of B. thetaiotaomicron occurred in 43 mM Na(+) correlating with the NHE3(-/-) mouse terminal ileum [Na(+)]. NHE3(-/-) terminal ileum displayed increased fut2 mRNA and fucosylation correlating with B. thetaiotaomicron growth. Inoculation of B. thetaiotaomicron in wild-type and NHE3(-/-) terminal ileum organoids displayed increased fut2 and fucosylation, indicating that B. thetaiotaomicron alone is sufficient for the increased fucosylation seen in vivo. These data demonstrate that loss of NHE3 alters the intestinal environment, leading to region-specific changes in bacteria, and shed light on the growth requirements of some gut microbiota members, which is vital for creating better treatments of complex diseases with an altered gut microbiota.
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Affiliation(s)
- Melinda A. Engevik
- Departments of 1Molecular and Cellular Physiology and ,3Digestive Health Center of Cincinnati Children's Hospital, Cincinnati, Ohio
| | - Eitaro Aihara
- Departments of 1Molecular and Cellular Physiology and ,3Digestive Health Center of Cincinnati Children's Hospital, Cincinnati, Ohio
| | - Marshall H. Montrose
- Departments of 1Molecular and Cellular Physiology and ,3Digestive Health Center of Cincinnati Children's Hospital, Cincinnati, Ohio
| | - Gary E. Shull
- 2Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati; ,3Digestive Health Center of Cincinnati Children's Hospital, Cincinnati, Ohio
| | - Daniel J. Hassett
- 2Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati;
| | - Roger T. Worrell
- Departments of 1Molecular and Cellular Physiology and ,3Digestive Health Center of Cincinnati Children's Hospital, Cincinnati, Ohio
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