1
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Duan XP, Zhang CB, Wang WH, Lin DH. Role of calcineurin in regulating renal potassium (K +) excretion: Mechanisms of calcineurin inhibitor-induced hyperkalemia. Acta Physiol (Oxf) 2024; 240:e14189. [PMID: 38860527 PMCID: PMC11250626 DOI: 10.1111/apha.14189] [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: 03/21/2024] [Revised: 05/28/2024] [Accepted: 05/30/2024] [Indexed: 06/12/2024]
Abstract
Calcineurin, protein phosphatase 2B (PP2B) or protein phosphatase 3 (PP3), is a calcium-dependent serine/threonine protein phosphatase. Calcineurin is widely expressed in the kidney and regulates renal Na+ and K+ transport. In the thick ascending limb, calcineurin plays a role in inhibiting NKCC2 function by promoting the dephosphorylation of the cotransporter and an intracellular sorting receptor, called sorting-related-receptor-with-A-type repeats (SORLA), is involved in modulating the effect of calcineurin on NKCC2. Calcineurin also participates in regulating thiazide-sensitive NaCl-cotransporter (NCC) in the distal convoluted tubule. The mechanisms by which calcineurin regulates NCC include directly dephosphorylation of NCC, regulating Kelch-like-3/CUL3 E3 ubiquitin-ligase complex, which is responsible for WNK (with-no-lysin-kinases) ubiquitination, and inhibiting Kir4.1/Kir5.1, which determines NCC expression/activity. Finally, calcineurin is also involved in regulating ROMK (Kir1.1) channels in the cortical collecting duct and Cyp11 2 expression in adrenal zona glomerulosa. In summary, calcineurin is involved in the regulation of NKCC2, NCC, and inwardly rectifying K+ channels in the kidney, and it also plays a role in modulating aldosterone synthesis in adrenal gland, which regulates epithelial-Na+-channel expression/activity. Thus, application of calcineurin inhibitors (CNIs) is expected to abrupt calcineurin-mediated regulation of transepithelial Na+ and K+ transport in the kidney. Consequently, CNIs cause hypertension, compromise renal K+ excretion, and induce hyperkalemia.
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Affiliation(s)
- Xin-Peng Duan
- Department of Physiology, Xuzhou Medical University, Xuzhou, China
| | - Cheng-Biao Zhang
- Department of Physiology, Xuzhou Medical University, Xuzhou, China
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York, USA
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2
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Berg P, Svendsen SL, Ayasse N, Sorensen MV, Leipziger J. Secretin: a hormone for HCO 3- homeostasis. Pflugers Arch 2024; 476:545-554. [PMID: 38221598 DOI: 10.1007/s00424-024-02906-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/22/2023] [Accepted: 01/02/2024] [Indexed: 01/16/2024]
Abstract
Secretin is a key hormone of the intestinal phase of digestion which activates pancreatic, bile duct and Brunner gland HCO3- secretion. Recently, the secretin receptor (SCTR) was also found in the basolateral membrane of the beta-intercalated cell (B-IC) of the collecting duct. Experimental addition of secretin triggers a pronounced activation of urinary HCO3- excretion, which is fully dependent on key functional proteins of the B-IC, namely apical pendrin and CFTR and the basolateral SCTR. Recent studies demonstrated that the SCTR knock-out mouse is unable to respond to an acute base load. Here, SCTR KO mice could not rapidly increase urine base excretion, developed prolonged metabolic alkalosis and exhibited marked compensatory hypoventilation. Here, we review the physiological effects of secretin with distinct focus on how secretin activates renal HCO3- excretion. We describe its new function as a hormone for HCO3- homeostasis.
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Affiliation(s)
- Peder Berg
- Department of Biomedicine, Physiology, Health, Aarhus University, Høegh-Guldbergsgade 10, Bld. 1115, 8000, Aarhus C, Denmark
| | - Samuel L Svendsen
- Department of Biomedicine, Physiology, Health, Aarhus University, Høegh-Guldbergsgade 10, Bld. 1115, 8000, Aarhus C, Denmark
| | - Niklas Ayasse
- Vth Department of Medicine, University Hospital Mannheim, Medical Faculty Mannheim of the University of Heidelberg, Mannheim, Germany
| | - Mads Vaarby Sorensen
- Department of Biomedicine, Physiology, Health, Aarhus University, Høegh-Guldbergsgade 10, Bld. 1115, 8000, Aarhus C, Denmark
| | - Jens Leipziger
- Department of Biomedicine, Physiology, Health, Aarhus University, Høegh-Guldbergsgade 10, Bld. 1115, 8000, Aarhus C, Denmark.
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3
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Park M, Cave G, Freebairn R. Metabolic acidosis in anaesthesia and critical care. BJA Educ 2024; 24:91-99. [PMID: 38375495 PMCID: PMC10874758 DOI: 10.1016/j.bjae.2023.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/21/2023] [Indexed: 02/21/2024] Open
Affiliation(s)
- M.A.J. Park
- Te Matau a Maui Hawke's Bay, Health New Zealand, Hastings, New Zealand
| | - G. Cave
- Te Matau a Maui Hawke's Bay, Health New Zealand, Hastings, New Zealand
| | - R.C. Freebairn
- Te Matau a Maui Hawke's Bay, Health New Zealand, Hastings, New Zealand
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4
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Hoogstraten CA, Hoenderop JG, de Baaij JHF. Mitochondrial Dysfunction in Kidney Tubulopathies. Annu Rev Physiol 2024; 86:379-403. [PMID: 38012047 DOI: 10.1146/annurev-physiol-042222-025000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Mitochondria play a key role in kidney physiology and pathology. They produce ATP to fuel energy-demanding water and solute reabsorption processes along the nephron. Moreover, mitochondria contribute to cellular health by the regulation of autophagy, (oxidative) stress responses, and apoptosis. Mitochondrial abundance is particularly high in cortical segments, including proximal and distal convoluted tubules. Dysfunction of the mitochondria has been described for tubulopathies such as Fanconi, Gitelman, and Bartter-like syndromes and renal tubular acidosis. In addition, mitochondrial cytopathies often affect renal (tubular) tissues, such as in Kearns-Sayre and Leigh syndromes. Nevertheless, the mechanisms by which mitochondrial dysfunction results in renal tubular diseases are only scarcely being explored. This review provides an overview of mitochondrial dysfunction in the development and progression of kidney tubulopathies. Furthermore, it emphasizes the need for further mechanistic investigations to identify links between mitochondrial function and renal electrolyte reabsorption.
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Affiliation(s)
- Charlotte A Hoogstraten
- Department of Medical Biosciences, Radboud University Medical Center, Nijmegen, The Netherlands;
| | - Joost G Hoenderop
- Department of Medical Biosciences, Radboud University Medical Center, Nijmegen, The Netherlands;
| | - Jeroen H F de Baaij
- Department of Medical Biosciences, Radboud University Medical Center, Nijmegen, The Netherlands;
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5
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Bulger DA, Griendling KK. Novel Mechanism by Which Extracellular Cyclic GMP Induces Natriuresis. Circ Res 2023; 132:1141-1143. [PMID: 37104563 PMCID: PMC10151062 DOI: 10.1161/circresaha.123.322778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Affiliation(s)
- David A Bulger
- Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA
| | - Kathy K Griendling
- Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA
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6
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Koirala A, Pourafshar N, Daneshmand A, Wilcox CS, Mannemuddhu SS, Arora N. Etiology and Management of Edema: A Review. ADVANCES IN KIDNEY DISEASE AND HEALTH 2023; 30:110-123. [PMID: 36868727 DOI: 10.1053/j.akdh.2022.12.002] [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: 06/21/2022] [Revised: 12/12/2022] [Accepted: 12/14/2022] [Indexed: 04/18/2023]
Abstract
The development of peripheral edema can often pose a significant diagnostic and therapeutic challenge for practitioners due to its association with a wide variety of underlying disorders ranging in severity. Updates to the original Starling's principle have provided new mechanistic insights into edema formation. Additionally, contemporary data highlighting the role of hypochloremia in the development of diuretic resistance provide a possible new therapeutic target. This article reviews the pathophysiology of edema formation and discusses implications for treatment.
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Affiliation(s)
- Abbal Koirala
- Division of Nephrology, University of Washington, Seattle, WA
| | - Negiin Pourafshar
- Division of Nephrology, MedStar Georgetown University Hospital, Washington DC
| | - Arvin Daneshmand
- Division of Nephrology, MedStar Georgetown University Hospital, Washington DC
| | | | | | - Nayan Arora
- Division of Nephrology, University of Washington, Seattle, WA.
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7
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Tawalbeh M, Aburizeg D, Abu Alragheb BO, Alaqrabawi WS, Dardas Z, Srour L, Altarayra BH, Zayed AA, El Omari Z, Azab B. SLC26A4 Phenotypic Variability Influences Intra- and Inter-Familial Diagnosis and Management. Genes (Basel) 2022; 13:genes13122192. [PMID: 36553459 PMCID: PMC9778369 DOI: 10.3390/genes13122192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 11/01/2022] [Accepted: 11/17/2022] [Indexed: 11/25/2022] Open
Abstract
SLC26A4 is one of the most common genes causing autosomal recessive non-syndromic sensorineural hearing loss (SNHL). It has been reported to cause Pendred Syndrome (PDS) and DFNB4 which is deafness with enlarged vestibular aqueduct (EVA). However, mutated SLC26A4 is not conclusive for having either DFNB4 or PDS. Three unrelated Jordanian families consisting of eight affected individuals with congenital bilateral hearing loss (HL) participated in this study. Whole-exome and Sanger sequencing were performed to investigate the underlying molecular etiology of HL. Further clinical investigations, including laboratory blood workup for the thyroid gland, CT scan for the temporal bone, and thyroid ultrasound were performed. Three disease-causing variants were identified in SLC26A4 in the three families, two of which were novel. Two families had a novel pathogenic homozygous splice-site accepter variant (c.165-1G>C), while the third family had compound heterozygous pathogenic variants (c.1446G>A; p.Trp482* and c.304G>A; p.Gly102Arg). Our approach helped in redirecting the diagnosis of several affected members of three different families from non-syndromic HL to syndromic HL. Two of the affected individuals had typical PDS, one had DFNB4, while the rest had atypical PDS. Our work emphasized the intra- and inter-familial variability of SLC26A4-related phenotypes. In addition, we highlighted the variable phenotypic impact of SLC26A4 on tailoring a personalized healthcare management.
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Affiliation(s)
- Mohamed Tawalbeh
- Department of Special Surgery, Jordan University Hospital, Amman 11942, Jordan
- Correspondence: (M.T.); (B.A.)
| | - Dunia Aburizeg
- Department of Pathology and Microbiology and Forensic Medicine, School of Medicine, The University of Jordan, Amman 11942, Jordan
| | - Bayan O. Abu Alragheb
- Department of Pathology and Microbiology and Forensic Medicine, School of Medicine, The University of Jordan, Amman 11942, Jordan
| | - Wala Sami Alaqrabawi
- Hearing and Speech Department, School of Rehabilitation Sciences, The University of Jordan, Amman 11942, Jordan
- Audiology Department, Faculty of Medical Sciences, Hacettepe University, Ankara 06100, Turkey
| | - Zain Dardas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Luma Srour
- Department of Pathology and Microbiology and Forensic Medicine, School of Medicine, The University of Jordan, Amman 11942, Jordan
| | | | - Ayman A. Zayed
- Division of Endocrinology, Diabetes & Metabolism, Department of Internal Medicine, Jordan University Hospital, Amman 11942, Jordan
| | - Zaid El Omari
- Otolaryngology, Head and Neck Surgery Department, Jordanian Royal Medical Services, Amman 11855, Jordan
| | - Bilal Azab
- Department of Pathology and Microbiology and Forensic Medicine, School of Medicine, The University of Jordan, Amman 11942, Jordan
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY 10032, USA
- Correspondence: (M.T.); (B.A.)
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8
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Gérard AO, Laurain A, Sicard A, Merino D, Pathak A, Drici MD, Favre G, Esnault VLM. New Strategies for Volume Control in Patients with Diabetes Mellitus, a Narrative Review. Pharmaceutics 2022; 14:pharmaceutics14081569. [PMID: 36015195 PMCID: PMC9413771 DOI: 10.3390/pharmaceutics14081569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 07/20/2022] [Accepted: 07/27/2022] [Indexed: 12/10/2022] Open
Abstract
Sodium is reabsorbed all along the renal tubules. The positive impacts of sodium-glucose cotransporter-2 inhibitors (SGLT2i), angiotensin receptor neprilysin inhibitor (ARNI) and mineralocorticoid receptor antagonists (MRA) on hard renal and/or cardiac endpoints calls for the role of diuretics in nephroprotection and cardioprotection in patients with diabetes mellitus to be reviewed. Here, we review: (a) the mechanisms of action of the available natriuretics; (b) the physiological adaptations to chronic loop diuretic usage that lead to increased sodium reabsorption in the proximal and distal convoluted tubules; (c) the physiology of sodium retention in patients with diabetes mellitus; and (d) the mechanisms of aldosterone breakthrough. We show the rationale for combined diuretics to target not only the loop of Henle, but also the proximal and distal convoluted tubules. Indeed, higher residual proteinuria in patients treated with renin-angiotensin-aldosterone system (RAAS) blockers portends poorer renal and cardiovascular outcomes. Diuretics are known to optimize the reduction of proteinuria, in addition to RAAS blockers, but may favor aldosterone breakthrough in the absence of MRA. The aim of our study is to support a combined diuretics strategy to improve the management of patients with diabetes mellitus and chronic kidney disease or heart failure.
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Affiliation(s)
- Alexandre O. Gérard
- Nephrology-Dialysis-Transplantation Department, Pasteur Hospital, Université Côte d’Azur, 06001 Nice, France; (A.O.G.); (A.L.); (A.S.); (G.F.)
- Pharmacology Department, Pasteur Hospital, Université Côte d’Azur, 06001 Nice, France; (D.M.); (M.-D.D.)
| | - Audrey Laurain
- Nephrology-Dialysis-Transplantation Department, Pasteur Hospital, Université Côte d’Azur, 06001 Nice, France; (A.O.G.); (A.L.); (A.S.); (G.F.)
| | - Antoine Sicard
- Nephrology-Dialysis-Transplantation Department, Pasteur Hospital, Université Côte d’Azur, 06001 Nice, France; (A.O.G.); (A.L.); (A.S.); (G.F.)
| | - Diane Merino
- Pharmacology Department, Pasteur Hospital, Université Côte d’Azur, 06001 Nice, France; (D.M.); (M.-D.D.)
| | - Atul Pathak
- Centre Hospitalier Princesse Grace, 98000 Monaco, Monaco;
| | - Milou-Daniel Drici
- Pharmacology Department, Pasteur Hospital, Université Côte d’Azur, 06001 Nice, France; (D.M.); (M.-D.D.)
| | - Guillaume Favre
- Nephrology-Dialysis-Transplantation Department, Pasteur Hospital, Université Côte d’Azur, 06001 Nice, France; (A.O.G.); (A.L.); (A.S.); (G.F.)
| | - Vincent L. M. Esnault
- Nephrology-Dialysis-Transplantation Department, Pasteur Hospital, Université Côte d’Azur, 06001 Nice, France; (A.O.G.); (A.L.); (A.S.); (G.F.)
- Correspondence:
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9
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Imenez Silva PH, Mohebbi N. Kidney metabolism and acid-base control: back to the basics. Pflugers Arch 2022; 474:919-934. [PMID: 35513635 PMCID: PMC9338915 DOI: 10.1007/s00424-022-02696-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 01/18/2023]
Abstract
Kidneys are central in the regulation of multiple physiological functions, such as removal of metabolic wastes and toxins, maintenance of electrolyte and fluid balance, and control of pH homeostasis. In addition, kidneys participate in systemic gluconeogenesis and in the production or activation of hormones. Acid-base conditions influence all these functions concomitantly. Healthy kidneys properly coordinate a series of physiological responses in the face of acute and chronic acid-base disorders. However, injured kidneys have a reduced capacity to adapt to such challenges. Chronic kidney disease patients are an example of individuals typically exposed to chronic and progressive metabolic acidosis. Their organisms undergo a series of alterations that brake large detrimental changes in the homeostasis of several parameters, but these alterations may also operate as further drivers of kidney damage. Acid-base disorders lead not only to changes in mechanisms involved in acid-base balance maintenance, but they also affect multiple other mechanisms tightly wired to it. In this review article, we explore the basic renal activities involved in the maintenance of acid-base balance and show how they are interconnected to cell energy metabolism and other important intracellular activities. These intertwined relationships have been investigated for more than a century, but a modern conceptual organization of these events is lacking. We propose that pH homeostasis indissociably interacts with central pathways that drive progression of chronic kidney disease, such as inflammation and metabolism, independent of etiology.
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Affiliation(s)
- Pedro Henrique Imenez Silva
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
- National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.
| | - Nilufar Mohebbi
- National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
- Praxis Und Dialysezentrum Zurich, Zurich, Switzerland
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10
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Berg P, Svendsen SL, Sorensen MV, Schreiber R, Kunzelmann K, Leipziger J. The molecular mechanism of CFTR- and secretin-dependent renal bicarbonate excretion. J Physiol 2021; 599:3003-3011. [PMID: 33963548 DOI: 10.1113/jp281285] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 04/12/2021] [Indexed: 11/08/2022] Open
Abstract
This review summarizes the newly discovered molecular mechanism of secretin-stimulated urine HCO3 - excretion and the role of cystic fibrosis transmembrane conductance regulator (CFTR) in renal HCO3 - excretion. The secretin receptor is functionally expressed in the basolateral membrane of the HCO3 - -secreting β-intercalated cells of the collecting duct. Here it activates a fast and efficient secretion of HCO3 - into the urine serving to normalize metabolic alkalosis. The ability to acutely increase renal base excretion is entirely dependent on functional pendrin (SLC26A4) and CFTR, and both proteins localize to the apical membrane of the β-intercalated cells. In cystic fibrosis mice and patients, this function is absent or markedly reduced. We discuss that the alkaline tide, namely the transient urine alkalinity after a meal, has now received a clear physiological explanation.
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Affiliation(s)
- Peder Berg
- Department of Biomedicine, Physiology, Health, Aarhus University, Aarhus, Denmark
| | - Samuel L Svendsen
- Department of Biomedicine, Physiology, Health, Aarhus University, Aarhus, Denmark
| | - Mads Vaarby Sorensen
- Department of Biomedicine, Physiology, Health, Aarhus University, Aarhus, Denmark
| | - Rainer Schreiber
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Karl Kunzelmann
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Jens Leipziger
- Department of Biomedicine, Physiology, Health, Aarhus University, Aarhus, Denmark
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11
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Zhao J, Feng WG, Wei Z, Zhou J, Chen XY, Zhang ZL. Follow-Up of Adefovir Dipivoxil Induced Osteomalacia: Clinical Characteristics and Genetic Predictors. Front Pharmacol 2021; 12:636352. [PMID: 33995038 PMCID: PMC8113870 DOI: 10.3389/fphar.2021.636352] [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: 12/19/2020] [Accepted: 04/16/2021] [Indexed: 11/13/2022] Open
Abstract
Adefovir dipivoxil (ADV) is widely used for chronic hepatitis B therapy in China. To explore the clinical features and prognosis of ADV-induced osteomalacia and to analyze the association between osteomalacia and genetic variants in 51 drug transporters genes. Clinical and follow-up data of the ADV-treated patients were collected. Target capture sequencing was used to identify genetic variations of 51 drug transporter genes. A total of 193 hepatitis B patients treated with ADV were enrolled, of whom 140 had osteomalacia. The other 53 without osteomalacia were included in the control group. The median duration of ADV treatment before the onset of osteomalacia was 6.5 years (range:1.5–7 years). We found that most patients with osteomalacia had hypophosphatemia, high serum alkaline phosphatase levels, hypouricemia, nondiabetic glycosuria, proteinuria. Stopping ADV administration, supplementing calcitriol and calcium were effective treatments. During 3–6 months of follow-up, the clinical symptoms and biochemical indicators of patients with osteomalacia have been significantly improved. There was no significant difference in duration of adefovir treatment in patients with or without osteomalacia (p = 0.791). Through regression analysis, we found that age was a risk factor for osteomalacia [per 1 year, odds ratio (OR), 1.053; 95% confidence interval (95% CI), 1.020–1.087; p = 0.015]. 1992 single nucleotide variants were found using target capture sequencing. However, the associations of genetic variants of 51 drug transporter genes and the risk of osteomalacia were negligible. Osteomalacia is prone to occur in patients with chronic hepatitis B treated with long-term ADV at a therapeutic dose. After standard treatment, the prognosis is mostly good. We failed to find genetic variants that can predict the risk of ADV-induced osteomalacia.
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Affiliation(s)
- Jiao Zhao
- Shanghai Clinical Research Center of Bone Disease, Department of Osteoporosis and Bone Disease, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Wei-Guang Feng
- Department of Hepatology, The Fourth People's Hospital of Huai'an, Huai'an, China
| | - Zhe Wei
- Shanghai Clinical Research Center of Bone Disease, Department of Osteoporosis and Bone Disease, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Jian Zhou
- Department of Hepatology, The Fourth People's Hospital of Huai'an, Huai'an, China
| | - Xiao-Yun Chen
- Department of Rheumatology, Shanghai University of Traditional Chinese Medicine Affiliated LongHua Hospital, Shanghai, China
| | - Zhen-Lin Zhang
- Shanghai Clinical Research Center of Bone Disease, Department of Osteoporosis and Bone Disease, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai, China
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12
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Berg P, Svendsen SL, Hoang TTL, Praetorius HA, Sorensen MV, Leipziger J. Impaired renal HCO 3 - secretion in CFTR deficient mice causes metabolic alkalosis during chronic base-loading. Acta Physiol (Oxf) 2021; 231:e13591. [PMID: 33270356 DOI: 10.1111/apha.13591] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 11/27/2020] [Accepted: 11/27/2020] [Indexed: 12/11/2022]
Abstract
AIM Cystic fibrosis patients have an increased risk of developing metabolic alkalosis presumably as a result of altered renal HCO3 - handling. In this study, we directly assess the kidneys' ability to compensate for a chronic base-load in the absence of functional CFTR. METHODS Comprehensive urine and blood acid-base analyses were done in anaesthetized WT mice or mice lacking either CFTR or pendrin, with or without 7 days of oral NaHCO3 loading. The in vivo experiments were complemented by a combination of immunoblotting and experiments with perfused isolated mouse cortical collecting ducts (CCD). RESULTS Base-loaded WT mice maintained acid-base homeostasis by elevating urinary pH and HCO3 - excretion and decreasing urinary net acid excretion. In contrast, pendrin KO mice and CFTR KO mice were unable to increase urinary pH and HCO3 - excretion and unable to decrease urinary net acid excretion sufficiently and thus developed metabolic alkalosis in response to the same base-load. The expression of pendrin was increased in response to the base-load in WT mice with a paralleled increased pendrin function in the perfused CCD. In CFTR KO mice, 7 days of base-loading did not upregulate pendrin expression and apical Cl- /HCO3 - exchange function was strongly blunted in the CCD. CONCLUSION CFTR KO mice develop metabolic alkalosis during a chronic base-load because they are unable to sufficiently elevate renal HCO3 - excretion. This can be explained by markedly reduced pendrin function in the absence of CFTR.
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Affiliation(s)
- Peder Berg
- Department of Biomedicine, Physiology Faculty of Health Aarhus University Aarhus C Denmark
| | - Samuel L. Svendsen
- Department of Biomedicine, Physiology Faculty of Health Aarhus University Aarhus C Denmark
| | - Thi Thuy Linh Hoang
- Department of Biomedicine, Physiology Faculty of Health Aarhus University Aarhus C Denmark
| | - Helle A. Praetorius
- Department of Biomedicine, Physiology Faculty of Health Aarhus University Aarhus C Denmark
| | - Mads V. Sorensen
- Department of Biomedicine, Physiology Faculty of Health Aarhus University Aarhus C Denmark
| | - Jens Leipziger
- Department of Biomedicine, Physiology Faculty of Health Aarhus University Aarhus C Denmark
- Aarhus Institute of Advanced Studies Aarhus University Aarhus C Denmark
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Abstract
The prevalence of cardiovascular and metabolic disease coupled with kidney dysfunction is increasing worldwide. This triad of disorders is associated with considerable morbidity and mortality as well as a substantial economic burden. Further understanding of the underlying pathophysiological mechanisms is important to develop novel preventive or therapeutic approaches. Among the proposed mechanisms, compromised nitric oxide (NO) bioactivity associated with oxidative stress is considered to be important. NO is a short-lived diatomic signalling molecule that exerts numerous effects on the kidneys, heart and vasculature as well as on peripheral metabolically active organs. The enzymatic L-arginine-dependent NO synthase (NOS) pathway is classically viewed as the main source of endogenous NO formation. However, the function of the NOS system is often compromised in various pathologies including kidney, cardiovascular and metabolic diseases. An alternative pathway, the nitrate-nitrite-NO pathway, enables endogenous or dietary-derived inorganic nitrate and nitrite to be recycled via serial reduction to form bioactive nitrogen species, including NO, independent of the NOS system. Signalling via these nitrogen species is linked with cGMP-dependent and independent mechanisms. Novel approaches to restoring NO homeostasis during NOS deficiency and oxidative stress have potential therapeutic applications in kidney, cardiovascular and metabolic disorders.
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14
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Berg P, Svendsen SL, Sorensen MV, Larsen CK, Andersen JF, Jensen-Fangel S, Jeppesen M, Schreiber R, Cabrita I, Kunzelmann K, Leipziger J. Impaired Renal HCO 3 - Excretion in Cystic Fibrosis. J Am Soc Nephrol 2020; 31:1711-1727. [PMID: 32703846 DOI: 10.1681/asn.2020010053] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 04/13/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Patients with cystic fibrosis (CF) do not respond with increased urinary HCO3 - excretion after stimulation with secretin and often present with metabolic alkalosis. METHODS By combining RT-PCR, immunohistochemistry, isolated tubule perfusion, in vitro cell studies, and in vivo studies in different mouse models, we elucidated the mechanism of secretin-induced urinary HCO3 - excretion. For CF patients and CF mice, we developed a HCO3 - drinking test to assess the role of the cystic fibrosis transmembrane conductance regulator (CFTR) in urinary HCO3 -excretion and applied it in the patients before and after treatment with the novel CFTR modulator drug, lumacaftor-ivacaftor. RESULTS β-Intercalated cells express basolateral secretin receptors and apical CFTR and pendrin. In vivo application of secretin induced a marked urinary alkalization, an effect absent in mice lacking pendrin or CFTR. In perfused cortical collecting ducts, secretin stimulated pendrin-dependent Cl-/HCO3 - exchange. In collecting ducts in CFTR knockout mice, baseline pendrin activity was significantly lower and not responsive to secretin. Notably, patients with CF (F508del/F508del) and CF mice showed a greatly attenuated or absent urinary HCO3 --excreting ability. In patients, treatment with the CFTR modulator drug lumacaftor-ivacaftor increased the renal ability to excrete HCO3 -. CONCLUSIONS These results define the mechanism of secretin-induced urinary HCO3 - excretion, explain metabolic alkalosis in patients with CF, and suggest feasibility of an in vivo human CF urine test to validate drug efficacy.
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Affiliation(s)
- Peder Berg
- Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus, Denmark
| | - Samuel L Svendsen
- Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus, Denmark
| | - Mads V Sorensen
- Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus, Denmark
| | - Casper K Larsen
- Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus, Denmark
| | - Jesper Frank Andersen
- Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus, Denmark
| | - Søren Jensen-Fangel
- Department of Infectious Diseases, Aarhus University Hospital, Aarhus, Denmark
| | - Majbritt Jeppesen
- Department of Infectious Diseases, Aarhus University Hospital, Aarhus, Denmark
| | - Rainer Schreiber
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Ines Cabrita
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Karl Kunzelmann
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Jens Leipziger
- Department of Biomedicine, Physiology and Biophysics, Aarhus University, Aarhus, Denmark
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15
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Genini A, Mohebbi N, Daryadel A, Bettoni C, Wagner CA. Adaptive response of the murine collecting duct to alkali loading. Pflugers Arch 2020; 472:1079-1092. [DOI: 10.1007/s00424-020-02423-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 05/31/2020] [Accepted: 06/19/2020] [Indexed: 01/14/2023]
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16
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Li M, Nishio SY, Naruse C, Riddell M, Sapski S, Katsuno T, Hikita T, Mizapourshafiyi F, Smith FM, Cooper LT, Lee MG, Asano M, Boettger T, Krueger M, Wietelmann A, Graumann J, Day BW, Boyd AW, Offermanns S, Kitajiri SI, Usami SI, Nakayama M. Digenic inheritance of mutations in EPHA2 and SLC26A4 in Pendred syndrome. Nat Commun 2020; 11:1343. [PMID: 32165640 PMCID: PMC7067772 DOI: 10.1038/s41467-020-15198-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 02/17/2020] [Indexed: 01/03/2023] Open
Abstract
Enlarged vestibular aqueduct (EVA) is one of the most commonly identified inner ear malformations in hearing loss patients including Pendred syndrome. While biallelic mutations of the SLC26A4 gene, encoding pendrin, causes non-syndromic hearing loss with EVA or Pendred syndrome, a considerable number of patients appear to carry mono-allelic mutation. This suggests faulty pendrin regulatory machinery results in hearing loss. Here we identify EPHA2 as another causative gene of Pendred syndrome with SLC26A4. EphA2 forms a protein complex with pendrin controlling pendrin localization, which is disrupted in some pathogenic forms of pendrin. Moreover, point mutations leading to amino acid substitution in the EPHA2 gene are identified from patients bearing mono-allelic mutation of SLC26A4. Ephrin-B2 binds to EphA2 triggering internalization with pendrin inducing EphA2 autophosphorylation weakly. The identified EphA2 mutants attenuate ephrin-B2- but not ephrin-A1-induced EphA2 internalization with pendrin. Our results uncover an unexpected role of the Eph/ephrin system in epithelial function. While biallelic mutations of the SLC26A4 gene cause non-syndromic hearing loss with enlarged vestibular aqueducts or Pendred syndrome, a considerable number of patients carry mono-allelic mutations. Here the authors identify EPHA2 as another causative gene of Pendred syndrome with SLC26A4.
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Affiliation(s)
- Mengnan Li
- Laboratory for Cell Polarity and Organogenesis, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.,DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, Philipps-Universität Marburg, Marburg, Germany
| | - Shin-Ya Nishio
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Chie Naruse
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Meghan Riddell
- Laboratory for Cell Polarity and Organogenesis, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Sabrina Sapski
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Tatsuya Katsuno
- Department of Otolaryngology - Head and Neck Surgery Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Takao Hikita
- Laboratory for Cell Polarity and Organogenesis, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Fatemeh Mizapourshafiyi
- Laboratory for Cell Polarity and Organogenesis, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.,DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, Philipps-Universität Marburg, Marburg, Germany
| | - Fiona M Smith
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Leanne T Cooper
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Min Goo Lee
- Department of Pharmacology, Yonsei University College of Medicine, Seoul, Korea
| | - Masahide Asano
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Thomas Boettger
- Department of Cardiac Development and Remodelling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Marcus Krueger
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Astrid Wietelmann
- MRI and µCT Service Group, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Johannes Graumann
- Scientific Service Group Biomolecular Mass Spectrometry Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany.,German Centre for Cardiovascular Research (DZHK), Partner Site - Rhine-Main, Berlin, Germany
| | - Bryan W Day
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Andrew W Boyd
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Stefan Offermanns
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Shin-Ichiro Kitajiri
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Shin-Ichi Usami
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Masanori Nakayama
- Laboratory for Cell Polarity and Organogenesis, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany. .,DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, Philipps-Universität Marburg, Marburg, Germany. .,Kumamoto University International Research Center for Medical Scinece, Kumamoto, Japan.
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17
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Recent insights into sodium and potassium handling by the aldosterone-sensitive distal nephron: implications on pathophysiology and drug discovery. J Nephrol 2020; 33:447-466. [DOI: 10.1007/s40620-020-00700-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 01/02/2020] [Indexed: 12/31/2022]
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18
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Mutig K, Bachmann S. Hyperkalemia and blood pressure regulation. Nephrol Dial Transplant 2019; 34:iii26-iii35. [PMID: 31800077 DOI: 10.1093/ndt/gfz218] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Indexed: 11/12/2022] Open
Abstract
Hypertension is common in the general population. Management of hypertensive patients at risk of hyperkalemia is challenging due to potential life-threatening complications such as cardiac arrest. Chronic hyperkalemia is often associated with impaired renal ability to excrete excessive potassium ions (K+). This may refer to chronic kidney disease or certain pharmacological interventions, including broadly used renin-angiotensin-aldosterone system and calcineurin inhibitors. Understanding the intrinsic mechanisms permitting kidney adaptations to hyperkalemia is critical for choosing therapeutic strategies. Valuable insights were obtained from the analysis of familial hyperkalemic hypertension (FHHt) syndrome, which became a classic model for coincidence of high blood pressure and hyperkalemia. FHHt can be caused by mutations in several genes, all of them resulting in excessive activity of with-no-lysine kinases (WNKs) in the distal nephron of the kidney. WNKs have been increasingly recognized as key signalling enzymes in the regulation of renal sodium ions (Na+) and K+ handling, enabling adaptive responses to systemic shifts of potassium homoeostasis consequent to variations in dietary potassium intake or disease. The WNK signalling pathway recruits a complex protein network mediating catalytic and non-catalytic effects of distinct WNK isoforms on relevant Na+- or K+-transporting proteins. In this review article, we summarize recent progress in understanding WNK signalling. An update of available models for renal adaptation to hyperkalemic conditions is presented. Consequences for blood pressure regulation are discussed. Pharmacological targeting of WNKs or their substrates offers promising options to manage hypertension while preventing hyperkalemia.
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Affiliation(s)
- Kerim Mutig
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Department of Pharmacology, I.M. Sechenov First Moscow State Medical University of the Ministry of Healthcare of the Russian Federation (Sechenovskiy University), Moscow, Russia
| | - Sebastian Bachmann
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
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19
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van der Wijst J, Belge H, Bindels RJM, Devuyst O. Learning Physiology From Inherited Kidney Disorders. Physiol Rev 2019; 99:1575-1653. [PMID: 31215303 DOI: 10.1152/physrev.00008.2018] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The identification of genes causing inherited kidney diseases yielded crucial insights in the molecular basis of disease and improved our understanding of physiological processes that operate in the kidney. Monogenic kidney disorders are caused by mutations in genes coding for a large variety of proteins including receptors, channels and transporters, enzymes, transcription factors, and structural components, operating in specialized cell types that perform highly regulated homeostatic functions. Common variants in some of these genes are also associated with complex traits, as evidenced by genome-wide association studies in the general population. In this review, we discuss how the molecular genetics of inherited disorders affecting different tubular segments of the nephron improved our understanding of various transport processes and of their involvement in homeostasis, while providing novel therapeutic targets. These include inherited disorders causing a dysfunction of the proximal tubule (renal Fanconi syndrome), with emphasis on epithelial differentiation and receptor-mediated endocytosis, or affecting the reabsorption of glucose, the handling of uric acid, and the reabsorption of sodium, calcium, and magnesium along the kidney tubule.
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Affiliation(s)
- Jenny van der Wijst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Hendrica Belge
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
| | - Olivier Devuyst
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center , Nijmegen , The Netherlands ; Institute of Physiology, University of Zurich , Zurich , Switzerland ; and Division of Nephrology, Institute of Experimental and Clinical Research (IREC), Medical School, Université catholique de Louvain, Brussels, Belgium
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20
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Evaluation of the pathophysiological mechanisms of salt-sensitive hypertension. Hypertens Res 2019; 42:1848-1857. [PMID: 31541221 DOI: 10.1038/s41440-019-0332-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 08/24/2019] [Accepted: 08/27/2019] [Indexed: 12/23/2022]
Abstract
The currently available data have indicated that dietary salt is directly correlated with blood pressure (BP) and the occurrence of hypertension. However, the salt sensitivity of BP is different in each individual. Genetic factors and environmental factors influence the salt sensitivity of BP. Obesity, stress, and aging are strongly associated with increased BP salt sensitivity. Indeed, a complex and interactive genetic and environmental system can determine an individual's BP salt sensitivity. However, the genetic/epigenetic determinants leading to salt sensitivity of BP are still challenging to identify primarily because lifestyle-related diseases, including hypertension, usually become a medical problem during adulthood, although their causes may be attributed to the earlier stages of ontogeny. The association between distinct developmental periods involves changes in gene expression, which include epigenetic phenomena. The role of epigenetic modification in the development of salt-sensitive hypertension is presently under investigation. Recently, we identified aberrant DNA methylation in the context of prenatally programmed hypertension. In this review, we summarize the existing knowledge regarding the pathophysiological mechanisms of salt-sensitive hypertension. Additionally, we discuss the contribution of epigenetic mechanisms in the development of salt-sensitive hypertension.
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21
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Abstract
Metabolic acidosis is defined as a pathologic process that, when unopposed, increases the concentration of hydrogen ions (H+) in the body and reduces the bicarbonate (HCO3-) concentration. Metabolic acidosis can be of a kidney origin or an extrarenal cause. Assessment of urinary ammonium excretion by calculating the urine anion gap or osmolal gap is a useful method to distinguish between these two causes. Extrarenal processes include increased endogenous acid production and accelerated loss of bicarbonate from the body. Metabolic acidosis of renal origin is due to a primary defect in renal acidification with no increase in extrarenal hydrogen ion production. This situation can occur because either the renal input of new bicarbonate is insufficient to regenerate the bicarbonate lost in buffering endogenous acid as with distal renal tubular acidosis (RTA) or the RTA of renal insufficiency, or the filtered bicarbonate is lost by kidney wasting as in proximal RTA. In either condition, because of loss of either NaHCO3 (proximal RTA) or NaA (distal RTA), effective extracellular volume is reduced and as a result the avidity for chloride reabsorption derived from the diet is increased and results in a hyperchloremic normal gap metabolic acidosis. The RTA of renal insufficiency is also characterized by a normal gap acidosis, however, with severe reductions in the glomerular filtration rate an anion gap metabolic acidosis eventually develops.
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Affiliation(s)
- Biff F Palmer
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA -
| | - Deborah J Clegg
- Department of Health Studies, College of Arts and Sciences, American University, Washington, DC, USA.,Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, University of California Los Angeles (UCLA), Los Angeles, CA, USA
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22
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A single-nucleus RNA-sequencing pipeline to decipher the molecular anatomy and pathophysiology of human kidneys. Nat Commun 2019; 10:2832. [PMID: 31249312 PMCID: PMC6597610 DOI: 10.1038/s41467-019-10861-2] [Citation(s) in RCA: 155] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 05/31/2019] [Indexed: 12/17/2022] Open
Abstract
Defining cellular and molecular identities within the kidney is necessary to understand its organization and function in health and disease. Here we demonstrate a reproducible method with minimal artifacts for single-nucleus Droplet-based RNA sequencing (snDrop-Seq) that we use to resolve thirty distinct cell populations in human adult kidney. We define molecular transition states along more than ten nephron segments spanning two major kidney regions. We further delineate cell type-specific expression of genes associated with chronic kidney disease, diabetes and hypertension, providing insight into possible targeted therapies. This includes expression of a hypertension-associated mechano-sensory ion channel in mesangial cells, and identification of proximal tubule cell populations defined by pathogenic expression signatures. Our fully optimized, quality-controlled transcriptomic profiling pipeline constitutes a tool for the generation of healthy and diseased molecular atlases applicable to clinical samples. Single-cell studies in solid tissues remain challenging and have benefited from the development of single-nuclei RNA sequencing strategies. Here Lake et al. apply single-nucleus RNA sequencing to human kidney tissues to provide a comprehensive molecular and cellular atlas of the human kidney, with potential implications for the understanding of kidney physiology and disease.
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23
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Shibata S. Role of Pendrin in the Pathophysiology of Aldosterone-Induced Hypertension. Am J Hypertens 2019; 32:607-613. [PMID: 30982848 DOI: 10.1093/ajh/hpz054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 04/11/2019] [Indexed: 11/14/2022] Open
Abstract
The recent advances in genetics and molecular biology have resulted in the characterization of key components that critically regulate renal NaCl transport and blood pressure. Pendrin is a Cl-/HCO3- exchanger that is highly expressed in thyroid, inner ear, and kidney. In the kidney, it is selectively present at the apical membrane in non-α intercalated cells of the connecting tubules and cortical collecting duct. Besides its role in acid/base homeostasis, accumulating studies using various genetically modified animals have provided compelling evidence that pendrin regulates extracellular fluid volume and electrolyte balance at the downstream of aldosterone signaling. We have shown that angiotensin II and aldosterone cooperatively control pendrin abundance partly through mammalian target of rapamycin signaling and mineralocorticoid receptor dephosphorylation, which is necessary for the kidney to prevent extracellular fluid loss and electrolyte disturbances under physiologic perturbations. In line with the experimental observations, several clinical data indicated that the impaired pendrin function can cause fluid and electrolyte abnormalities in humans. The purpose of this review is to provide an update on the recent progress regarding the role of pendrin in fluid and electrolyte homeostasis, as well as in the pathophysiology of hypertension associated with mineralocorticoid receptor signaling.
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Affiliation(s)
- Shigeru Shibata
- Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan
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24
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Abstract
Classic and nonclassic renin-angiotensin systems (RAS) are 2 sides of an ubiquitous endocrine/paracrine cascade regulating blood pressure and homeostasis. Angiotensin II and angiotensin-converting enzyme (ACE) levels are associated with severity of disease in the critically ill, and are central to the physiology and the pathogenesis of circulatory shock. Angiotensin (1-7) and ACE2 act as an endogenous counterregulatory arm to the angiotensin II/ACE axis. The tissue-based RAS has paracrine effects dissociated from those of the circulating RAS. Exogenous angiotensin II or ACE2 may improve the outcome of septic shock and acute respiratory distress syndrome, respectively.
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Affiliation(s)
- Laurent Bitker
- Department of Intensive Care, ICU Research Office, Austin Hospital, 145 Studley Road, Heidelberg, Victoria 3084, Australia.
| | - Louise M Burrell
- Department of Medicine, University of Melbourne, Austin Health, Austin Hospital, 145 Studley Road, Heidelberg, Victoria 3084, Australia
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25
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Abstract
Metabolic alkalosis defined by the increase of both plasma HCO3- level (>26 mmol/L) and blood arterial pH (>7.43) is quite frequent and usually accompanied by hypokalemia. Its pathogenesis requires both the generation of alkalosis and its maintenance. Generation may be due to excessive hydrogen ion loss by the gastrointestinal tract (e.g. vomiting) or by the kidney (e.g. use of loop diuretics) or may be due to exogenous base gain. Maintenance reflects the inability of the kidney to excrete the excess of bicarbonate because of hypovolemia, chloride depletion, hypokalemia, hyperaldosteronism, renal failure or a combination of these factors. The evaluation of volemic status and measurement of urinary Cl- and plasma levels of renin and aldosterone are crucial to identify the cause(s) of metabolic alkalosis. The cornerstone of treatment is the correction of existing depletions and the prevention of further losses. In vomiting-induced chloride depletion alkalosis, infusion of potassium chloride restores the excretion of bicarbonate by the kidney.
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Affiliation(s)
- Valentine Gillion
- Division of Nephrology, Cliniques universitaires Saint-Luc, Brussels, Belgium
| | - Michel Jadoul
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Olivier Devuyst
- Division of Nephrology, Cliniques universitaires Saint-Luc, Brussels, Belgium
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Jean-Michel Pochet
- Division of Nephrology, Cliniques universitaires Saint-Luc, Brussels, Belgium
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26
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Romero CA, Carretero OA. A Novel Mechanism of Renal Microcirculation Regulation: Connecting Tubule-Glomerular Feedback. Curr Hypertens Rep 2019; 21:8. [PMID: 30659366 DOI: 10.1007/s11906-019-0911-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE OF REVIEW In this review, we summarized the current knowledge of connecting tubule-glomerular feedback (CTGF), a novel mechanism of renal microcirculation regulation that integrates sodium handling in the connecting tubule (CNT) with kidney hemodynamics. RECENT FINDINGS Connecting tubule-glomerular feedback is a crosstalk communication between the CNT and the afferent arteriole (Af-Art), initiated by sodium chloride through the epithelial sodium channel (ENaC). High sodium in the CNT induces Af-Art vasodilation, increasing glomerular pressure and the glomerular filtration rate and favoring sodium excretion. CTGF antagonized and reset tubuloglomerular feedback and thus increased sodium excretion. CTGF is absent in spontaneous hypertensive rats and is overactivated in Dahl salt-sensitive rats. CTGF is also modulated by angiotensin II and aldosterone. CTGF is a feedback mechanism that integrates sodium handling in the CNT with glomerular hemodynamics. Lack of CTGF could promote hypertension, and CTGF overactivation may favor glomerular damage and proteinuria. More studies are needed to explore the alterations in renal microcirculation and the role of these alterations in the genesis of hypertension and glomerular damage in animals and humans. KEY POINTS • CTGF is a vasodilator mechanism that regulates afferent arteriole resistance. • CTGF is absent in spontaneous hypertensive rats and overactivated in Dahl salt-sensitive rats. • CTGF in excess may promote glomerular damage and proteinuria, while the absence may participate in sodium retention and hypertension.
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Affiliation(s)
- Cesar A Romero
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 2799 West Grand Boulevard, Detroit, MI, 48202-2689, USA.
| | - Oscar A Carretero
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 2799 West Grand Boulevard, Detroit, MI, 48202-2689, USA
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27
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Wu P, Gao ZX, Su XT, Wang MX, Wang WH, Lin DH. Kir4.1/Kir5.1 Activity Is Essential for Dietary Sodium Intake-Induced Modulation of Na-Cl Cotransporter. J Am Soc Nephrol 2018; 30:216-227. [PMID: 30559144 DOI: 10.1681/asn.2018080799] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 11/13/2018] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Dietary sodium intake regulates the thiazide-sensitive Na-Cl cotransporter (NCC) in the distal convoluted tubule (DCT). Whether the basolateral, inwardly rectifying potassium channel Kir4.1/Kir5.1 (a heterotetramer of Kir4.1/Kir5.1) in the DCT is essential for mediating the effect of dietary sodium intake on NCC activity is unknown. METHODS We used electrophysiology, renal clearance techniques, and immunoblotting to examine effects of Kir4.1/Kir5.1 in the DCT and NCC in wild-type and kidney-specific Kir4.1 knockout mice. RESULTS Low sodium intake stimulated basolateral Kir4.1/Kir5.1 activity, increased basolateral K+ conductance, and hyperpolarized the membrane. Conversely, high sodium intake inhibited the potassium channel, decreased basolateral K+ currents, and depolarized the membrane. Low sodium intake increased total and phosphorylated NCC expression and augmented hydrochlorothiazide-induced natriuresis; high sodium intake had opposite effects. Thus, elevated NCC activity induced by low sodium intake was associated with upregulation of Kir4.1/Kir5.1 activity in the DCT, whereas inhibition of NCC activity by high sodium intake was associated with diminished Kir4.1/Kir5.1 activity. In contrast, dietary sodium intake did not affect NCC activity in knockout mice. Further, Kir4.1 deletion not only abolished basolateral K+ conductance and depolarized the DCT membrane, but also abrogated the stimulating effects induced by low sodium intake on basolateral K+ conductance and hyperpolarization. Finally, dietary sodium intake did not alter urinary potassium excretion rate in hypokalemic knockout and wild-type mice. CONCLUSIONS Stimulation of Kir4.1/Kir5.1 by low intake of dietary sodium is essential for NCC upregulation, and inhibition of Kir4.1/Kir5.1 induced by high sodium intake is a key step for downregulation of NCC.
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Affiliation(s)
- Peng Wu
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Zhong-Xiuzi Gao
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Xiao-Tong Su
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Ming-Xiao Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York
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28
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Teulon J, Planelles G, Sepúlveda FV, Andrini O, Lourdel S, Paulais M. Renal Chloride Channels in Relation to Sodium Chloride Transport. Compr Physiol 2018; 9:301-342. [DOI: 10.1002/cphy.c180024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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29
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Saritas T, Puelles VG, Su XT, McCormick JA, Welling PA, Ellison DH. Optical Clearing in the Kidney Reveals Potassium-Mediated Tubule Remodeling. Cell Rep 2018; 25:2668-2675.e3. [PMID: 30517856 PMCID: PMC6339512 DOI: 10.1016/j.celrep.2018.11.021] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 10/08/2018] [Accepted: 11/01/2018] [Indexed: 02/07/2023] Open
Abstract
Distal nephron remodeling contributes to the pathophysiology of many clinically relevant scenarios, including diuretic resistance and certain Mendelian disorders of blood pressure. However, constitutive genetic disruptions are likely to have substantial developmental effects in this segment, and whether tubule remodeling upon physiological stimuli is a normal homeostatic mechanism is not known. Since the distal nephron acts as a potassium sensor, we assessed proliferation and tubule length in three dimensions upon dietary or inducible genetic manipulation by using optical clearing of adult mouse kidneys, whole-mount immunolabeling, and advanced light microscopy. We show that dietary potassium restriction leads promptly to proliferation of various nephron segments, including the distal convoluted tubule, whereas disruption of the potassium sensor Kir4.1 causes atrophy, despite ambient hypokalemia. These results provide proof that kidney tubules adapt rapidly to diet and indicate the power of clearing approaches to assess cell number and tubule length in healthy and diseased kidney.
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Affiliation(s)
- Turgay Saritas
- Division of Nephrology and Hypertension, Oregon Health & Science University, Portland, OR 97239, USA; Division of Nephrology and Clinical Immunology, University Hospital RWTH Aachen, Aachen 52074, Germany.
| | - Victor G Puelles
- Division of Nephrology and Clinical Immunology, University Hospital RWTH Aachen, Aachen 52074, Germany; III. Department of Medicine, University Medical Center, Hamburg-Eppendorf, Hamburg 20246, Germany; Department of Nephrology, Monash Health, Melbourne, VIC 3168, Australia
| | - Xiao-Tong Su
- Division of Nephrology and Hypertension, Oregon Health & Science University, Portland, OR 97239, USA
| | - James A McCormick
- Division of Nephrology and Hypertension, Oregon Health & Science University, Portland, OR 97239, USA
| | - Paul A Welling
- Department of Physiology, University of Maryland, Baltimore, MD 21201, USA; Fondation LeDucq Transatlantic Networks of Excellence, Paris 75116, France
| | - David H Ellison
- Division of Nephrology and Hypertension, Oregon Health & Science University, Portland, OR 97239, USA; Fondation LeDucq Transatlantic Networks of Excellence, Paris 75116, France; Renal Section, Veterans Affairs Portland Health Care System, Portland, OR 97239, USA
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30
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Sanz AB, Ramos AM, Soler MJ, Sanchez-Niño MD, Fernandez-Fernandez B, Perez-Gomez MV, Ortega MR, Alvarez-Llamas G, Ortiz A. Advances in understanding the role of angiotensin-regulated proteins in kidney diseases. Expert Rev Proteomics 2018; 16:77-92. [DOI: 10.1080/14789450.2018.1545577] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Ana Belén Sanz
- Nephrology, IIS-Fundacion Jimenez Diaz and Universidad Autonoma de Madrid, Madrid, Spain
| | - Adrian Mario Ramos
- Nephrology, IIS-Fundacion Jimenez Diaz and Universidad Autonoma de Madrid, Madrid, Spain
| | - Maria Jose Soler
- Department of Nephrology, Hospital del Mar-IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain
| | | | | | | | - Marta Ruiz Ortega
- Nephrology, IIS-Fundacion Jimenez Diaz and Universidad Autonoma de Madrid, Madrid, Spain
| | - Gloria Alvarez-Llamas
- Nephrology, IIS-Fundacion Jimenez Diaz and Universidad Autonoma de Madrid, Madrid, Spain
| | - Alberto Ortiz
- Nephrology, IIS-Fundacion Jimenez Diaz and Universidad Autonoma de Madrid, Madrid, Spain
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31
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Park AY, Plotsky PM, Pham TD, Pacak K, Wynne BM, Wall SM, Lazo‐Fernandez Y. Blood collection in unstressed, conscious, and freely moving mice through implantation of catheters in the jugular vein: a new simplified protocol. Physiol Rep 2018; 6:e13904. [PMID: 30426706 PMCID: PMC6234146 DOI: 10.14814/phy2.13904] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 09/26/2018] [Accepted: 09/27/2018] [Indexed: 02/06/2023] Open
Abstract
The mouse has become the most common mammalian animal model used in biomedical research. However, laboratory techniques used previously in rats and other larger animals to sample blood had to be adapted in mice due to their lower mouse plasma volume. Sampling is further confounded by the variability in plasma hormone and metabolite concentrations that can occur from the stress or the anesthesia that accompanies the collection. In this article, we describe in detail a protocol we developed for blood sampling in conscious, unrestrained mice. Our protocol implements the use of chronic indwelling catheters in the right external jugular vein, allowing the mice to recover fully in their home cages, untethered until the time of blood sampling. This protocol employs catheters that remain patent for days and does not require the purchase of expensive equipment. We validated this protocol by measuring the time course of plasma norepinephrine (NE) concentration during and after the relief of acute immobilization stress in wild type (WT) and pendrin knockout (KO) mice and compared these results with our previously published values. We found that following relief from immobilization stress, it takes longer for plasma NE concentration to return to basal levels in the pendrin KO than in the wild type mice. These results highlight the potential utility of this protocol and the potential role of pendrin in the neuroendocrine response to acute stress.
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Affiliation(s)
- Annie Y. Park
- Department of MedicineEmory University School of MedicineAtlantaGeorgia
| | - Paul M. Plotsky
- Department of Psychiatry & Behavioral SciencesEmory University School of MedicineAtlantaGeorgia
| | - Truyen D. Pham
- Department of MedicineEmory University School of MedicineAtlantaGeorgia
| | - Karel Pacak
- Program in Reproductive and Adult EndocrinologyEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMaryland
| | - Brandi M. Wynne
- Department of MedicineEmory University School of MedicineAtlantaGeorgia
| | - Susan M. Wall
- Department of MedicineEmory University School of MedicineAtlantaGeorgia
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32
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Phelan PJ, Rheault MN. Hearing loss and renal syndromes. Pediatr Nephrol 2018; 33:1671-1683. [PMID: 29130116 DOI: 10.1007/s00467-017-3835-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 10/24/2017] [Accepted: 10/25/2017] [Indexed: 01/26/2023]
Abstract
The association between ear and kidney abnormalities has long been recognized; however, the connection between these two disparate organs is not always straightforward. Although Alport syndrome is the most well-known, there are over 20 disorders that need to be considered in the differential diagnosis of patients with both ear and kidney abnormalities. Commonalities are present between the kidney and ear in a number of structural proteins, developmentally important transcription factors, ciliary proteins, and channel proteins, and mutations in these pathways can lead to disease in both organ systems. This manuscript reviews the congenital disorders with both hearing and kidney manifestations.
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Affiliation(s)
- Paul J Phelan
- Department of Nephrology, Royal Infirmary of Edinburgh, NHS Lothian, Edinburgh, UK
| | - Michelle N Rheault
- Department of Pediatrics, Division of Nephrology, University of Minnesota Masonic Children's Hospital, Minneapolis, MN, USA.
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33
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Pendred, pendrin, pseudohypoaldosteronism type II, and renal tubular acidosis. Kidney Int 2018; 94:457-459. [DOI: 10.1016/j.kint.2018.05.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 05/18/2018] [Indexed: 11/18/2022]
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34
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Adenylyl cyclase 6 is required for maintaining acid-base homeostasis. Clin Sci (Lond) 2018; 132:1779-1796. [PMID: 29941522 DOI: 10.1042/cs20180060] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 06/15/2018] [Accepted: 06/25/2018] [Indexed: 12/14/2022]
Abstract
Adenylyl cyclase (AC) isoform 6 (AC6) is highly expressed throughout the renal tubule and collecting duct (CD), catalyzes the synthesis of cAMP and contributes to various aspects of renal transport. Several proteins involved in acid-base homeostasis are regulated by cAMP. In the present study, we assess the relative contribution of AC6 to overall acid-base regulation using mice with global deletion of AC6 (AC6-/-) or newly generated mice lacking AC6 in the renal tubule and CD (AC6loxloxPax8Cre). Higher energy expenditure in AC6-/- relative to wild-type (WT) mice, was associated with lower urinary pH, mild alkalosis in conjunction with elevated blood HCO3- concentrations, and significantly higher renal abundance of the H+-ATPase B1 subunit. In contrast with WT mice, AC6-/- mice have a less pronounced increase in urinary pH after 8 days of HCO3- challenge, which is associated with increased blood pH and HCO3- concentrations. Immunohistochemistry demonstrated that AC6 was expressed in intercalated cells (IC), but subcellular distribution of the H+-ATPase B1 subunit, pendrin, and the anion exchangers 1 and 2 in AC6-/- mice was normal. In the AC6-/- mice, H+-ATPase B1 subunit levels after HCO3- challenge were greater, which correlated with a higher number of type A IC. In contrast with the AC6-/- mice, AC6loxloxPax8Cre mice had normal urinary pH under baseline conditions but higher blood HCO3- than controls after HCO3- challenge. In conclusion, AC6 is required for maintaining normal acid-base homeostasis and energy expenditure. Under baseline conditions, renal AC6 is redundant for acid-base balance but becomes important under alkaline conditions.
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35
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Himmel NJ, Wang Y, Rodriguez DA, Sun MA, Blount MA. Chronic lithium treatment induces novel patterns of pendrin localization and expression. Am J Physiol Renal Physiol 2018; 315:F313-F322. [PMID: 29667915 PMCID: PMC6139525 DOI: 10.1152/ajprenal.00065.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/04/2018] [Accepted: 04/12/2018] [Indexed: 12/25/2022] Open
Abstract
Prolonged lithium treatment is associated with various renal side effects and is known to induce inner medullary collecting duct (IMCD) remodeling. In animals treated with lithium, the fraction of intercalated cells (ICs), which are responsible for acid-base homeostasis, increases compared with renal principal cells (PCs). To investigate the intricacies of lithium-induced IMCD remodeling, male Sprague-Dawley rats were fed a lithium-enriched diet for 0,1, 2, 3, 6, 9, or 12 wk. Urine osmolality was decreased at 1 wk, and from 2 to 12 wk, animals were severely polyuric. After 6 wk of lithium treatment, approximately one-quarter of the cells in the initial IMCD expressed vacuolar H+-ATPase, an IC marker. These cells were localized in portions of the inner medulla, where ICs are not normally found. Pendrin, a Cl-/[Formula: see text] exchanger, is normally expressed only in two IC subtypes found in the convoluted tubule, the cortical collecting duct, and the connecting tubule. At 6 wk of lithium treatment, we observed various patterns of pendrin localization and expression in the rat IMCD, including a novel phenotype wherein pendrin was coexpressed with aquaporin-4. These observations collectively suggest that renal IMCD cell plasticity may play an important role in lithium-induced IMCD remodeling.
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Affiliation(s)
- Nathaniel J Himmel
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Yirong Wang
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Daniel A Rodriguez
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Michael A Sun
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Mitsi A Blount
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
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36
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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: 27] [Impact Index Per Article: 4.5] [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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37
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Qian Q. Dietary Influence on Body Fluid Acid-Base and Volume Balance: The Deleterious "Norm" Furthers and Cloaks Subclinical Pathophysiology. Nutrients 2018; 10:E778. [PMID: 29914153 PMCID: PMC6024597 DOI: 10.3390/nu10060778] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 06/08/2018] [Accepted: 06/12/2018] [Indexed: 02/07/2023] Open
Abstract
The popular modern diet, characterized by an excess of animal protein and salt but insufficient in fruits, vegetables and water, is a poor fit for human physiological and homeostatic regulatory systems. Sustained net acid and sodium retention, coupled with an insufficient intake of cardiovascular protective potassium-rich foods and hydration in the modern diet can give rise to debilitating chronic organ dysfunction and ultimately, mortality. This holds true, especially in our aging population who are already facing inevitable decline in organ functional reserve. Importantly, in most cases, despite the mismatch and adverse effects to multiple organ systems, plasma electrolyte and acid-base parameters can, on the surface, be maintained within a “normal” reference range, primarily by activating (often maximally activating) compensatory homeostatic mechanisms. These diet-induced effects can thus be clinically silent for decades. Embodied in the chronic corrective homeostatic processes, however, are real risks for multiorgan damage. According to the Dietary Guideline Advisory Committee (DGAC), half of American adults have one or more chronic diseases that are preventable with dietary modification. Here, homeostasis of body fluid acid-base, sodium, potassium and water is examined. Our current dietary habits and their required regulatory adaptation, maladaptation and relevant physiology and pathophysiology are discussed. A framework of dietary modifications to avoid a propensity for maladaptation and thus lowers the risks of common modern diseases (primary prevention) and minimizes the risk of chronic and age-related disease progression (secondary prevention) is emphasized. Although there are other variables at play, a key to restoring the all-important dietary potassium to sodium ratio is greater consumption of vegetables/fruits and adopting salt temperance. Dietary and nutritional optimization is an under-emphasized area of health care that has an enormous potential to temper the epidemics of prevalent chronic diseases in modern society and improve population health.
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Affiliation(s)
- Qi Qian
- Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, School of Medicine, Rochester, MN 55905, USA.
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38
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Worcester EM, Bergsland KJ, Gillen DL, Coe FL. Mechanism for higher urine pH in normal women compared with men. Am J Physiol Renal Physiol 2017; 314:F623-F629. [PMID: 29357436 DOI: 10.1152/ajprenal.00494.2017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Regulation of acid-base metabolism maintains the pH of body fluids within a tight range. Urine pH (UpH) is also regulated under normal conditions. Median pH of 24-h urines is ~6, but others have noted that UpH in women is higher than men, which has been attributed to differences in diet. If true, it would help to explain the fact that calcium phosphate stones, which form at higher urine pH, are much more common in women than in men. We studied 14 normal subjects (7 men and 7 women) fed identical meals in a Clinical Research Center. Urine and blood samples were collected during fasting and after meals. UpH of women (6.74 ± 0.11) exceeded that of men (6.07 ± 0.17) fed, but not fasting, and UpH rose significantly with meals in women but not men. Serum and urine total CO2 rose with meals in women but not men, and in women net acid excretion fell to zero during the fed period. In a general linear model adjusted for age, sex, and weight, net gastrointestinal anion uptake was the main predictor of UpH and was significantly higher in women (3.9 ± 0.6) than men (1.8 ± 0.7) in the fed period. Urine citrate, an anion absorbed by the gastrointestinal tract, was higher in women than men in the fed state, and fractional excretion of citrate was higher in women than men. The higher fed UpH in women is related to a greater absorption of food anions and raises 24-h UpH.
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Affiliation(s)
- Elaine M Worcester
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
| | | | - Daniel L Gillen
- Department of Statistics, University of California , Irvine, California
| | - Fredric L Coe
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
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39
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Dhondup T, Qian Q. Acid-Base and Electrolyte Disorders in Patients with and without Chronic Kidney Disease: An Update. KIDNEY DISEASES (BASEL, SWITZERLAND) 2017; 3:136-148. [PMID: 29344508 PMCID: PMC5757582 DOI: 10.1159/000479968] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 08/03/2017] [Indexed: 12/14/2022]
Abstract
Kidneys play a pivotal role in the maintenance and regulation of acid-base and electrolyte homeostasis, which is the prerequisite for numerous metabolic processes and organ functions in the human body. Chronic kidney diseases compromise the regulatory functions, resulting in alterations in electrolyte and acid-base balance that can be life-threatening. In this review, we discuss the renal regulations of electrolyte and acid-base balance and several common disorders including metabolic acidosis, alkalosis, dysnatremia, dyskalemia, and dysmagnesemia. Common disorders in chronic kidney disease are also discussed. The most recent and relevant advances on pathophysiology, clinical characteristics, diagnosis, and management of these conditions have been incorporated.
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Affiliation(s)
| | - Qi Qian
- Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
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40
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Wall SM. Renal intercalated cells and blood pressure regulation. Kidney Res Clin Pract 2017; 36:305-317. [PMID: 29285423 PMCID: PMC5743040 DOI: 10.23876/j.krcp.2017.36.4.305] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 11/17/2017] [Accepted: 11/20/2017] [Indexed: 12/12/2022] Open
Abstract
Type B and non-A, non-B intercalated cells are found within the connecting tubule and the cortical collecting duct. Of these cell types, type B intercalated cells are known to mediate Cl- absorption and HCO3- secretion largely through pendrin-dependent Cl-/HCO3- exchange. This exchange is stimulated by angiotensin II administration and is also stimulated in models of metabolic alkalosis, for instance after aldosterone or NaHCO3 administration. In some rodent models, pendrin-mediated HCO3- secretion modulates acid-base balance. However, the role of pendrin in blood pressure regulation is likely of more physiological or clinical significance. Pendrin regulates blood pressure not only by mediating aldosterone-sensitive Cl- absorption, but also by modulating the aldosterone response for epithelial Na+ channel (ENaC)-mediated Na+ absorption. Pendrin regulates ENaC through changes in open channel of probability, channel surface density, and channels subunit total protein abundance. Thus, aldosterone stimulates ENaC activity through both direct and indirect effects, the latter occurring through its stimulation of pendrin expression and function. Therefore, pendrin contributes to the aldosterone pressor response. Pendrin may also modulate blood pressure in part through its action in the adrenal medulla, where it modulates the release of catecholamines, or through an indirect effect on vascular contractile force. This review describes how aldosterone and angiotensin II-induced signaling regulate pendrin and the contributory role of pendrin in distal nephron function and blood pressure.
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Affiliation(s)
- Susan M. Wall
- Departments of Medicine, Emory University School of Medicine, Atlanta, GA,
USA
- Physiology, Emory University School of Medicine, Atlanta, GA,
USA
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41
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Kleyman TR, Kashlan OB, Hughey RP. Epithelial Na + Channel Regulation by Extracellular and Intracellular Factors. Annu Rev Physiol 2017; 80:263-281. [PMID: 29120692 DOI: 10.1146/annurev-physiol-021317-121143] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Epithelial Na+ channels (ENaCs) are members of the ENaC/degenerin family of ion channels that evolved to respond to extracellular factors. In addition to being expressed in the distal aspects of the nephron, where ENaCs couple the absorption of filtered Na+ to K+ secretion, these channels are found in other epithelia as well as nonepithelial tissues. This review addresses mechanisms by which ENaC activity is regulated by extracellular factors, including proteases, Na+, and shear stress. It also addresses other factors, including acidic phospholipids and modification of ENaC cytoplasmic cysteine residues by palmitoylation, which enhance channel activity by altering interactions of the channel with the plasma membrane.
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Affiliation(s)
- Thomas R Kleyman
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA; .,Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.,Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
| | - Ossama B Kashlan
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA; .,Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Rebecca P Hughey
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA; .,Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.,Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania 15219, USA
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42
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Hirohama D, Ayuzawa N, Ueda K, Nishimoto M, Kawarazaki W, Watanabe A, Shimosawa T, Marumo T, Shibata S, Fujita T. Aldosterone Is Essential for Angiotensin II-Induced Upregulation of Pendrin. J Am Soc Nephrol 2017; 29:57-68. [PMID: 29021385 DOI: 10.1681/asn.2017030243] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Accepted: 07/18/2017] [Indexed: 12/17/2022] Open
Abstract
The renin-angiotensin-aldosterone system has an important role in the control of fluid homeostasis and BP during volume depletion. Dietary salt restriction elevates circulating angiotensin II (AngII) and aldosterone levels, increasing levels of the Cl-/HCO3- exchanger pendrin in β-intercalated cells and the Na+-Cl- cotransporter (NCC) in distal convoluted tubules. However, the independent roles of AngII and aldosterone in regulating these levels remain unclear. In C57BL/6J mice receiving a low-salt diet or AngII infusion, we evaluated the membrane protein abundance of pendrin and NCC; assessed the phosphorylation of the mineralocorticoid receptor, which selectively inhibits aldosterone binding in intercalated cells; and measured BP by radiotelemetry in pendrin-knockout and wild-type mice. A low-salt diet or AngII infusion upregulated NCC and pendrin levels, decreased the phosphorylation of mineralocorticoid receptor in β-intercalated cells, and increased plasma aldosterone levels. Notably, a low-salt diet did not alter BP in wild-type mice, but significantly decreased BP in pendrin-knockout mice. To dissect the roles of AngII and aldosterone, we performed adrenalectomies in mice to remove aldosterone from the circulation. In adrenalectomized mice, AngII infusion again upregulated NCC expression, but did not affect pendrin expression despite the decreased phosphorylation of mineralocorticoid receptor. By contrast, AngII and aldosterone coadministration markedly elevated pendrin levels in adrenalectomized mice. Our results indicate that aldosterone is necessary for AngII-induced pendrin upregulation, and suggest that pendrin contributes to the maintenance of normal BP in cooperation with NCC during activation of the renin-angiotensin-aldosterone system by dietary salt restriction.
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Affiliation(s)
- Daigoro Hirohama
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan;
| | - Nobuhiro Ayuzawa
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Kohei Ueda
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Mitsuhiro Nishimoto
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Wakako Kawarazaki
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Atsushi Watanabe
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Tatsuo Shimosawa
- Department of Clinical Laboratory, School of Medicine, International University of Health and Welfare, Chiba, Japan
| | - Takeshi Marumo
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Shigeru Shibata
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan.,Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan; and
| | - Toshiro Fujita
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan; .,CREST, Japan Science and Technology Agency, Tokyo, Japan
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43
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Honda K, Kim SH, Kelly MC, Burns JC, Constance L, Li X, Zhou F, Hoa M, Kelley MW, Wangemann P, Morell RJ, Griffith AJ. Molecular architecture underlying fluid absorption by the developing inner ear. eLife 2017; 6. [PMID: 28994389 PMCID: PMC5634787 DOI: 10.7554/elife.26851] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 09/10/2017] [Indexed: 12/26/2022] Open
Abstract
Mutations of SLC26A4 are a common cause of hearing loss associated with enlargement of the endolymphatic sac (EES). Slc26a4 expression in the developing mouse endolymphatic sac is required for acquisition of normal inner ear structure and function. Here, we show that the mouse endolymphatic sac absorbs fluid in an SLC26A4-dependent fashion. Fluid absorption was sensitive to ouabain and gadolinium but insensitive to benzamil, bafilomycin and S3226. Single-cell RNA-seq analysis of pre- and postnatal endolymphatic sacs demonstrates two types of differentiated cells. Early ribosome-rich cells (RRCs) have a transcriptomic signature suggesting expression and secretion of extracellular proteins, while mature RRCs express genes implicated in innate immunity. The transcriptomic signature of mitochondria-rich cells (MRCs) indicates that they mediate vectorial ion transport. We propose a molecular mechanism for resorption of NaCl by MRCs during development, and conclude that disruption of this mechanism is the root cause of hearing loss associated with EES.
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Affiliation(s)
- Keiji Honda
- Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Sung Huhn Kim
- Anatomy and Physiology Department, Kansas State University, Manhattan, United States
| | - Michael C Kelly
- Developmental Neuroscience Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Joseph C Burns
- Developmental Neuroscience Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Laura Constance
- Anatomy and Physiology Department, Kansas State University, Manhattan, United States
| | - Xiangming Li
- Anatomy and Physiology Department, Kansas State University, Manhattan, United States
| | - Fei Zhou
- Anatomy and Physiology Department, Kansas State University, Manhattan, United States
| | - Michael Hoa
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Matthew W Kelley
- Developmental Neuroscience Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Philine Wangemann
- Anatomy and Physiology Department, Kansas State University, Manhattan, United States
| | - Robert J Morell
- Genomics and Computational Biology Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Andrew J Griffith
- Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
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Anuk AT, Kose S, Fırat C, Ozer E, Altunyurt S. Pendrin Expression in Preeclampsia: A Prospective Immunohistochemical Staining Study on Placental Bed Biopsies. Fetal Pediatr Pathol 2017; 36:364-372. [PMID: 28949777 DOI: 10.1080/15513815.2017.1346016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
INTRODUCTION To assess the pendrin expression density in placental bed biopsies from preeclampsia cases in comparison with healthy term controls. MATERIAL AND METHODS A prospective case-control study with 106 placental bed biopsies obtained during cesarean deliveries. Pendrin expression was evaluated by immunohistochemical staining in different hypertensive disorders of pregnancy. RESULTS Pendrin immunostaining frequency was higher in the hypertensive disorders group (p: 0.024), which was a result of the high frequency in the early-onset preeclampsia group. Uterine artery pulsatility indices were higher in pendrin positive patients than in the negatives in the case group. Gravidity was not found to affect the pendrin expression frequency in the placental bed. CONCLUSION Placental ischemia seems to be an important determinant of pendrin expression in pregnant decidua. Increased pendrin density in early-onset preeclampsia could be a pathogenetic mechanism in or a part of the adaptational response to the development of the hypertension.
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Affiliation(s)
- Ali T Anuk
- a Department of Obstetrics and Gynecology , Dokuz Eylul University School of Medicine , Balcova, Izmir , Turkey
| | - Semir Kose
- b Division of Perinatology, Department of Obstetrics and Gynecology , Dokuz Eylul University School of Medicine , Balcova, Izmir , Turkey
| | - Canan Fırat
- c Department of Medical Pathology , Dokuz Eylul University School of Medicine , Balcova, Izmir , Turkey
| | - Erdener Ozer
- c Department of Medical Pathology , Dokuz Eylul University School of Medicine , Balcova, Izmir , Turkey
| | - Sabahattin Altunyurt
- b Division of Perinatology, Department of Obstetrics and Gynecology , Dokuz Eylul University School of Medicine , Balcova, Izmir , Turkey
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Xu N, Hirohama D, Ishizawa K, Chang WX, Shimosawa T, Fujita T, Uchida S, Shibata S. Hypokalemia and Pendrin Induction by Aldosterone. Hypertension 2017; 69:855-862. [PMID: 28289181 DOI: 10.1161/hypertensionaha.116.08519] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 10/18/2016] [Accepted: 02/13/2017] [Indexed: 11/16/2022]
Abstract
Aldosterone plays an important role in regulating Na-Cl reabsorption and blood pressure. Epithelial Na+ channel, Na+-Cl- cotransporter, and Cl-/HCO3- exchanger pendrin are the major mediators of Na-Cl transport in the aldosterone-sensitive distal nephron. Existing evidence also suggests that plasma K+ concentration affects renal Na-Cl handling. In this study, we posited that hypokalemia modulates the effects of aldosterone on pendrin in hyperaldosteronism. Chronic aldosterone infusion in mice increased pendrin levels at the plasma membrane, and correcting hypokalemia in this model almost completely blocked pendrin upregulation. However, hypokalemia induced by a low-K+ diet resulted in pendrin downregulation along with reduced plasma aldosterone levels, indicating that both hypokalemia and aldosterone excess are necessary for pendrin induction. In contrast, decreased plasma K+ levels were sufficient to increase Na+-Cl- cotransporter levels. We found that phosphorylation of mineralocorticoid receptor that prevents aldosterone binding in intercalated cells was suppressed by hypokalemia, which resulted in enhanced pendrin response to aldosterone, explaining the coordinated action of aldosterone and hypokalemia in pendrin regulation. Finally, to address the physiological significance of our observations, we administered aldosterone to mice lacking pendrin. Notably, plasma K+ levels were significantly lower in pendrin knockout mice (2.7±0.1 mmol/L) than in wild-type mice (3.0±0.1 mmol/L) after aldosterone infusion, demonstrating that pendrin alleviates hypokalemia in a state of aldosterone excess. These data indicate that the decreased plasma K+ levels promote pendrin induction by aldosterone, which, in concert with Na+-Cl- cotransporter, counteracts the progression of hypokalemia but promotes hypertension in primary aldosterone excess.
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Affiliation(s)
- Ning Xu
- From the Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan (N.X., K.I., S.U., S.S.); Department of Nephrology, Tianjin First Central Hospital, China (N.X., W.X.C.); and Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (D.H., T.F., S.S.) and Department of Clinical Laboratory, School of Medicine (T.S.), The University of Tokyo, Japan
| | - Daigoro Hirohama
- From the Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan (N.X., K.I., S.U., S.S.); Department of Nephrology, Tianjin First Central Hospital, China (N.X., W.X.C.); and Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (D.H., T.F., S.S.) and Department of Clinical Laboratory, School of Medicine (T.S.), The University of Tokyo, Japan
| | - Kenichi Ishizawa
- From the Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan (N.X., K.I., S.U., S.S.); Department of Nephrology, Tianjin First Central Hospital, China (N.X., W.X.C.); and Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (D.H., T.F., S.S.) and Department of Clinical Laboratory, School of Medicine (T.S.), The University of Tokyo, Japan
| | - Wen Xiu Chang
- From the Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan (N.X., K.I., S.U., S.S.); Department of Nephrology, Tianjin First Central Hospital, China (N.X., W.X.C.); and Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (D.H., T.F., S.S.) and Department of Clinical Laboratory, School of Medicine (T.S.), The University of Tokyo, Japan
| | - Tatsuo Shimosawa
- From the Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan (N.X., K.I., S.U., S.S.); Department of Nephrology, Tianjin First Central Hospital, China (N.X., W.X.C.); and Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (D.H., T.F., S.S.) and Department of Clinical Laboratory, School of Medicine (T.S.), The University of Tokyo, Japan
| | - Toshiro Fujita
- From the Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan (N.X., K.I., S.U., S.S.); Department of Nephrology, Tianjin First Central Hospital, China (N.X., W.X.C.); and Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (D.H., T.F., S.S.) and Department of Clinical Laboratory, School of Medicine (T.S.), The University of Tokyo, Japan
| | - Shunya Uchida
- From the Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan (N.X., K.I., S.U., S.S.); Department of Nephrology, Tianjin First Central Hospital, China (N.X., W.X.C.); and Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (D.H., T.F., S.S.) and Department of Clinical Laboratory, School of Medicine (T.S.), The University of Tokyo, Japan
| | - Shigeru Shibata
- From the Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, Tokyo, Japan (N.X., K.I., S.U., S.S.); Department of Nephrology, Tianjin First Central Hospital, China (N.X., W.X.C.); and Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (D.H., T.F., S.S.) and Department of Clinical Laboratory, School of Medicine (T.S.), The University of Tokyo, Japan.
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Abstract
Pendred syndrome is an autosomal recessive disorder that is classically defined by the combination of sensorineural deafness/hearing impairment, goiter, and an abnormal organification of iodide with or without hypothyroidism. The hallmark of the syndrome is the impaired hearing, which is associated with inner ear malformations such as an enlarged vestibular aqueduct (EVA). The thyroid phenotype is variable and may be modified by the nutritional iodine intake. Pendred syndrome is caused by biallelic mutations in the SLC26A4/PDS gene, which encodes the multifunctional anion exchanger pendrin. Pendrin has affinity for chloride, iodide, and bicarbonate, among other anions. In the inner ear, pendrin functions as a chloride/bicarbonate exchanger that is essential for maintaining the composition and the potential of the endolymph. In the thyroid, pendrin is expressed at the apical membrane of thyroid cells facing the follicular lumen. Functional studies have demonstrated that pendrin can mediate iodide efflux in heterologous cells. This, together with the thyroid phenotype observed in humans (goiter, impaired iodine organification) suggests that pendrin could be involved in iodide efflux into the lumen, one of the steps required for thyroid hormone synthesis. Iodide efflux can, however, also occur in the absence of pendrin suggesting that other exchangers or channels are involved. It has been suggested that Anoctamin 1 (ANO1/TMEM16A), a calcium-activated anion channel, which is also expressed at the apical membrane of thyrocytes, could participate in mediating apical efflux. In the kidney, pendrin is involved in bicarbonate secretion and chloride reabsorption. While there is no renal phenotype under basal conditions, severe metabolic alkalosis has been reported in Pendred syndrome patients exposed to an increased alkali load. This review provides an overview on the clinical spectrum of Pendred syndrome, the functional data on pendrin with a focus on its potential role in the thyroid, as well as the controversy surrounding the relative physiological roles of pendrin and anoctamin.
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Affiliation(s)
- Jean-Louis Wémeau
- Université de Lille 2, Centre Hospitalier Régional Universitaire de Lille, Clinique Endocrinologique Marc-Linquette, 59037 Lille, France.
| | - Peter Kopp
- Northwestern University, Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Tarry 15, 303 East Chicago Avenue, Chicago, IL 60611, USA.
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Fallahzadeh MA, Dormanesh B, Fallahzadeh MK, Roozbeh J, Fallahzadeh MH, Sagheb MM. Acetazolamide and Hydrochlorothiazide Followed by Furosemide Versus Furosemide and Hydrochlorothiazide Followed by Furosemide for the Treatment of Adults With Nephrotic Edema: A Randomized Trial. Am J Kidney Dis 2016; 69:420-427. [PMID: 28043731 DOI: 10.1053/j.ajkd.2016.10.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 10/09/2016] [Indexed: 11/11/2022]
Abstract
BACKGROUND Nephrotic edema is considered refractory if it does not respond to maximum or near-maximum doses of loop diuretics. This condition can be treated with loop diuretics and thiazides. However, animal studies show that the simultaneous downregulation of pendrin with acetazolamide and inhibition of the sodium-chloride cotransporter with hydrochlorothiazide generates significant diuresis, and furosemide administration following a pendrin inhibitor potentiates furosemide's diuretic effect. Therefore, we performed this study to compare the efficacy of acetazolamide and hydrochlorothiazide followed by furosemide versus furosemide and hydrochlorothiazide followed by furosemide for treatment of refractory nephrotic edema. STUDY DESIGN Randomized, double-blind, 2-arm, parallel trial. SETTING & PARTICIPANTS 20 patients with refractory nephrotic edema despite treatment with 80mg of furosemide daily and creatinine clearance > 60mL/min. INTERVENTION Patients were randomly assigned to 2 groups: group 1 (n=10) received 250mg of acetazolamide and 50mg of hydrochlorothiazide daily and group 2 (n=10) received 40mg of furosemide and 50mg of hydrochlorothiazide daily for 1 week in phase 1. In phase 2, both groups received 40mg of furosemide daily for 2 weeks. OUTCOMES The primary outcome was absolute change in weight before and at the end of each phase. MEASUREMENTS Weight and 24-hour urine volume at baseline and the end of each phase. RESULTS The mean weight decrease was of significantly larger magnitude in group 1 compared with group 2 at the end of phase 1 (-1.4±0.52 [SD] vs -0.65±0.41kg; P=0.001) and phase 2 (-1.6±0.84 vs -0.5±0.47kg; P=0.005). The increase in 24-hour urine volume was also significantly higher in group 1 at the end of phase 2. LIMITATIONS Small sample size, short follow-up duration, and lack of serum bicarbonate and chloride measurement. CONCLUSIONS Acetazolamide and hydrochlorothiazide followed by furosemide is more effective than furosemide and hydrochlorothiazide followed by furosemide for the treatment of refractory nephrotic edema.
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Affiliation(s)
- Mohammad Amin Fallahzadeh
- AJA University of Medical Sciences, Tehran, Iran; Shiraz Nephro-Urology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | | | | | - Jamshid Roozbeh
- Shiraz Nephro-Urology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | | | - Mohammad Mahdi Sagheb
- Shiraz Nephro-Urology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
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Mittal R, Aranke M, Debs LH, Nguyen D, Patel AP, Grati M, Mittal J, Yan D, Chapagain P, Eshraghi AA, Liu XZ. Indispensable Role of Ion Channels and Transporters in the Auditory System. J Cell Physiol 2016; 232:743-758. [DOI: 10.1002/jcp.25631] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 09/30/2016] [Indexed: 12/18/2022]
Affiliation(s)
- Rahul Mittal
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Mayank Aranke
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Luca H. Debs
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Desiree Nguyen
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Amit P. Patel
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - M'hamed Grati
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Jeenu Mittal
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Denise Yan
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Prem Chapagain
- Department of Physics; Florida International University; Miami Florida
- Biomolecular Science Institute; Florida International University; Miami Florida
| | - Adrien A. Eshraghi
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
| | - Xue Zhong Liu
- Department of Otolaryngology; University of Miami Miller School of Medicine; Miami Florida
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Affiliation(s)
- Carsten A Wagner
- National Center for Competence in Research Kidney.CH and Institute of Physiology, University of Zurich, Zurich, Switzerland
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50
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Cil O, Haggie PM, Phuan PW, Tan JA, Verkman AS. Small-Molecule Inhibitors of Pendrin Potentiate the Diuretic Action of Furosemide. J Am Soc Nephrol 2016; 27:3706-3714. [PMID: 27153921 DOI: 10.1681/asn.2015121312] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/18/2016] [Indexed: 11/03/2022] Open
Abstract
Pendrin is a Cl-/HCO3- exchanger expressed in type B and non-A, non-B intercalated cells in the distal nephron, where it facilitates Cl- absorption and is involved in Na+ absorption and acid-base balance. Pendrin-knockout mice show no fluid-electrolyte abnormalities under baseline conditions, although mice with double knockout of pendrin and the Na+/Cl- cotransporter (NCC) manifest profound salt wasting. Thus, pendrin may attenuate diuretic-induced salt loss, but this function remains unconfirmed. To clarify the physiologic role of pendrin under conditions not confounded by gene knockout, and to test the potential utility of pendrin inhibitors for diuretic therapy, we tested in mice a small-molecule pendrin inhibitor identified from a high-throughput screen. In vitro, a pyrazole-thiophenesulfonamide, PDSinh-C01, inhibited Cl-/anion exchange mediated by mouse pendrin with a 50% inhibitory concentration of 1-3 µM, without affecting other major kidney tubule transporters. Administration of PDSinh-C01 to mice at predicted therapeutic doses, determined from serum and urine pharmacokinetics, did not affect urine output, osmolality, salt excretion, or acid-base balance. However, in mice treated acutely with furosemide, administration of PDSinh-C01 produced a 30% increase in urine output, with increased Na+ and Cl- excretion. In mice treated long term with furosemide, in which renal pendrin is upregulated, PDSinh-C01 produced a 60% increase in urine output. Our findings clarify the role of pendrin in kidney function and suggest pendrin inhibition as a novel approach to potentiate the action of loop diuretics. Such combination therapy might enhance diuresis and salt excretion for treatment of hypertension and edema, perhaps including diuretic-resistant edema.
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Affiliation(s)
- Onur Cil
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, California
| | - Peter M Haggie
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, California
| | - Puay-Wah Phuan
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, California
| | - Joseph-Anthony Tan
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, California
| | - Alan S Verkman
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, California
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