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Schork A, Vogel E, Bohnert BN, Essigke D, Wörn M, Fischer I, Heyne N, Birkenfeld AL, Artunc F. Amiloride versus furosemide for the treatment of edema in patients with nephrotic syndrome: A pilot study (AMILOR). Acta Physiol (Oxf) 2024:e14183. [PMID: 38822593 DOI: 10.1111/apha.14183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 05/14/2024] [Accepted: 05/18/2024] [Indexed: 06/03/2024]
Abstract
AIM In rodent models of nephrotic syndrome (NS), edema formation was prevented by blockade of the epithelial sodium channel ENaC with amiloride. However, apart from case reports, there is no evidence favoring ENaC blockade in patients with NS. METHODS The monocentric randomized controlled AMILOR study investigated the antiedematous effect of amiloride (starting dose 5 mg/day, max. 15 mg/day) in comparison to standard therapy with the loop diuretic furosemide (40 mg/day, max. 120 mg/day) over 16 days. Overhydration (OH) was measured by bioimpedance spectroscopy (BCM, Fresenius). Depending on the OH response, diuretic dose was adjusted on days 2, 5, 8 and 12, and if necessary, hydrochlorothiazide (HCT) was added from d8 (12.5 mg/day, max. 25 mg/day). The primary endpoint was the decrease in OH on d8. The study was terminated prematurely due to insufficient recruitment and a low statistical power due to a low actual effect size. RESULTS Median baseline OH was +26.4 (interquartile range 15.5-35.1)% extracellular water (ECW) in the amiloride arm and + 27.9 (24.1-29.4)% ECW in the furosemide arm and decreased by 1.95 (0.80-6.40) and 5.15 (0.90-8.30)% ECW after 8 days, respectively, and by 10.10 (1.30-14.40) and 7.40 (2.80-10.10)% ECW after 16 days, respectively. OH decrease on d8 and d16 was not significantly different between both arms. CONCLUSION The AMILOR study is the first randomized controlled pilot study suggesting a similar antiedematous effect as furosemide. Further studies are required to better define the role of amiloride in NS (EudraCT 2019-002607-18).
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Affiliation(s)
- Anja Schork
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Elisabeth Vogel
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Bernhard N Bohnert
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Daniel Essigke
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Matthias Wörn
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Imma Fischer
- Institute for Clinical Epidemiology and Applied Biometry, University Hospital Tübingen, Tübingen, Germany
| | - Nils Heyne
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Andreas L Birkenfeld
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
| | - Ferruh Artunc
- Division of Diabetology, Endocrinology and Nephrology, Department of Internal Medicine IV, University Hospital Tübingen, Tübingen, Germany
- Institute of Diabetes Research and Metabolic Diseases (IDM) of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany
- German Center for Diabetes Research (DZD), Tübingen, Germany
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Taban-Sadeghi M, Khani E, Khezripour K, Enamzadeh E, Safaei N, Entezari-Maleki T. Effects of Triamterene in Hospitalized Patients with Heart Failure and Diuretic Resistance: A Randomized Clinical Trial. J Clin Pharmacol 2023; 63:1352-1358. [PMID: 37493211 DOI: 10.1002/jcph.2321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 07/20/2023] [Indexed: 07/27/2023]
Abstract
Due to the potential benefits of triamterene in diuretic resistance, this study was performed to assess whether triamterene add-on to the standard treatment of heart failure (HF)-related diuretic resistance improves outcomes. A randomized clinical trial was performed on 45 hospitalized patients with HF with reduced ejection fraction who had diuretic resistance. Patients were randomized to receive either triamterene 50 mg plus hydrochlorothiazide 25 mg (n = 23) or hydrochlorothiazide 50 mg alone (n = 22) until hospital discharge. The primary outcomes were changes in weight and fluid input-to-output ratio. Secondary outcomes were respiratory rate, hospitalization duration, serum sodium and potassium, estimated glomerular filtration rate, creatinine, and blood urea nitrogen levels during the study period. The mean (standard deviation) of weight changes was not significantly different in the intervention and the control groups (-6.3 [4.8] vs -4.8 [2.4] kg, respectively; P = .1). No significant differences were shown in input-to-output changes between the 2 groups (208.0 [243.4] in the intervention and 600.2 [250.3] in the control group; P = .4). Although the respiratory rate of triamterene-treated patients decreased, the difference did not reach statistical significance (P = .2). Other secondary outcomes were also similar in both groups. This study did not support the use of triamterene as an add-on therapy for patients with HF-related diuretic resistance.
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Affiliation(s)
| | - Elnaz Khani
- Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Kimia Khezripour
- Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Elgar Enamzadeh
- Cardiovascular Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Naser Safaei
- Cardiovascular Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Taher Entezari-Maleki
- Cardiovascular Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
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Chang CH, Yu HJ, Hou YC. The exacerbated hypokalemia in membranous glomerulonephritis due to proximal tubular injury: a neglect issue from a case report and literature review. BMC Nephrol 2023; 24:98. [PMID: 37061666 PMCID: PMC10105930 DOI: 10.1186/s12882-023-03130-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 03/20/2023] [Indexed: 04/17/2023] Open
Abstract
BACKGROUND Membranous glomerulonephritis is the most common primary etiology for the nephrotic syndrome in adults. Beyond the clinical hallmark of nephrotic syndrome such as fluid overloading, dyslipidemia and hypoalbuminemia, the dysregulated homeostasis of potassium and its possible mechanism is seldomly discussed, and its association with the clinical course of membranous GN is lacking. CASE PRESENTATION A 65 year-old female attended to our emergent department for progressive lower leg edema after taking 15-h of flight. Hypoalbuminemia and hyperlipidemia were both noted, and 24-h urinary total protein was up to 17,950 mg/day. Elevated creatin-phospho-kinase developed at the initial presentation with hypokalemia due to excressive renal excretion. Glycosuria without elevated glycated Hemoglobin occurred. The pathology of kidney biopsy revealed subepithelial immunocomplex deposits with spike formation in the electron microscopy and the positive anti-Phosphlipase A2 receptor antibodies(PLA-2R) with hallmark of membranous glomerulonephritis. In the light microscopy, the vacuolization of proximal tubules was noted, which contributed to the potassium wasting. After 1 year following up duration, the patient's proteinuria persisted after maintenance treatment with calcineurin inhibitor. CONCLUSION Hypokalemia is a neglected issue in the membranous glomerulonephritis. Unlike the previous literature, our patient had the vacuolization of proximal tubule at the initial presentation with hypokalemia, which might contribute the potassium wasting. The proximal tubular damage with hypokalemia might be a predictive factor for membranous glomerulonephritis.
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Affiliation(s)
- Chih-Hao Chang
- Department of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Municipal Tucheng Hospital, New Taipei City, Taiwan
| | - Hui-Jung Yu
- Department of Pathology, Cardinal Tien Hospital, School of Medicine, Fu-Jen Catholic Univer, sity, New Taipei City, Taiwan
| | - Yi-Chou Hou
- Department of Internal Medicine, Cardinal Tien Hospital An-Kang Branch, School of Medicine, Fu-Jen Catholic University, Hsin-Tien District, New Taipei City, 23155, Taiwan.
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van de Wouw J, Joles JA. Albumin is an interface between blood plasma and cell membrane, and not just a sponge. Clin Kidney J 2021; 15:624-634. [PMID: 35371452 PMCID: PMC8967674 DOI: 10.1093/ckj/sfab194] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Indexed: 12/16/2022] Open
Abstract
Albumin is the most abundant protein in blood plasma and acts as a carrier for many circulating molecules. Hypoalbuminaemia, mostly caused by either renal or liver disease or malnutrition, can perturb vascular homeostasis and is involved in the development of multiple diseases. Here we review four functions of albumin and the consequences of hypoalbuminaemia on vascular homeostasis. (i) Albumin is the main determinant of plasma colloid osmotic pressure. Hypoalbuminaemia was therefore thought to be the main mechanism for oedema in nephrotic syndrome (NS), however, experimental studies showed that intrarenal mechanisms rather than hypoalbuminaemia determine formation and, in particular, maintenance of oedema. (ii) Albumin functions as an interface between lysophosphatidylcholine (LPC) and circulating factors (lipoproteins and erythrocytes) and the endothelium. Consequently, hypoalbuminaemia results in higher LPC levels in lipoproteins and erythrocyte membrane, thereby increasing atherosclerotic properties of low-density lipoprotein and blood viscosity, respectively. Furthermore, albumin dose-dependently restores LPC-induced inhibition of vasodilation. (iii) Hypoalbuminaemia impacts on vascular nitric oxide (NO) signalling by directly increasing NO production in endothelial cells, leading to reduced NO sensitivity of vascular smooth muscle cells. (iv) Lastly, albumin binds free fatty acids (FFAs). FFAs can induce vascular smooth muscle cell apoptosis, uncouple endothelial NO synthase and decrease endothelium-dependent vasodilation. Unbound FFAs can increase the formation of reactive oxygen species by mitochondrial uncoupling in multiple cell types and induce hypertriglyceridemia in NS. In conclusion, albumin acts as an interface in the circulation and hypoalbuminaemia impairs multiple aspects of vascular function that may underlie the association of hypoalbuminaemia with adverse outcomes. However, hypoalbuminaemia is not a key to oedema in NS. These insights have therapeutic implications.
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Affiliation(s)
| | - Jaap A Joles
- Department of Nephrology and Hypertension, University Medical Center, Utrecht, the Netherlands
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Hinrichs GR, Weyer K, Friis UG, Svenningsen P, Lund IK, Nielsen R, Mollet G, Antignac C, Bistrup C, Jensen BL, Birn H. Sodium retention by uPA-plasmin-ENaC in nephrotic syndrome-Authors reply. Acta Physiol (Oxf) 2020; 228:e13432. [PMID: 31845496 DOI: 10.1111/apha.13432] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 12/06/2019] [Accepted: 12/11/2019] [Indexed: 01/13/2023]
Affiliation(s)
- Gitte R. Hinrichs
- Department of Molecular Medicine, Cardiovascular and Renal Research University of Southern Denmark Odense Denmark
| | - Kathrin Weyer
- Department of Biomedicine Aarhus University Aarhus Denmark
| | - Ulla G. Friis
- Department of Molecular Medicine, Cardiovascular and Renal Research University of Southern Denmark Odense Denmark
| | - Per Svenningsen
- Department of Molecular Medicine, Cardiovascular and Renal Research University of Southern Denmark Odense Denmark
| | - Ida Katrine Lund
- The Finsen Laboratory Biotech Research & Innovation Centre (BRIC) University of Copenhagen Copenhagen Denmark
| | - Rikke Nielsen
- Department of Biomedicine Aarhus University Aarhus Denmark
| | - Géraldine Mollet
- Laboratory of Hereditary Kidney Diseases Paris Descartes‐Sorbonne Paris Cité University Paris France
| | - Corinne Antignac
- Laboratory of Hereditary Kidney Diseases Paris Descartes‐Sorbonne Paris Cité University Paris France
- Department of Genetics Necker HospitalAssistance Publique‐Hôpitaux de Paris Paris France
| | - Claus Bistrup
- Department of Nephrology Odense University Hospital Odense Denmark
- Department of Clinical Research University of Southern Denmark Odense Denmark
| | - Boye L. Jensen
- Department of Molecular Medicine, Cardiovascular and Renal Research University of Southern Denmark Odense Denmark
| | - Henrik Birn
- Department of Biomedicine Aarhus University Aarhus Denmark
- Department of Renal Medicine Aarhus University Hospital Aarhus Denmark
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Hinrichs GR, Weyer K, Friis UG, Svenningsen P, Lund IK, Nielsen R, Mollet G, Antignac C, Bistrup C, Jensen BL, Birn H. Urokinase-type plasminogen activator contributes to amiloride-sensitive sodium retention in nephrotic range glomerular proteinuria in mice. Acta Physiol (Oxf) 2019; 227:e13362. [PMID: 31423748 DOI: 10.1111/apha.13362] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 08/12/2019] [Accepted: 08/15/2019] [Indexed: 12/12/2022]
Abstract
AIM Activation of sodium reabsorption by urinary proteases has been implicated in sodium retention associated with nephrotic syndrome. The study was designed to test the hypothesis that nephrotic proteinuria in mice after conditional deletion of podocin leads to urokinase-dependent, amiloride-sensitive plasmin-mediated sodium and water retention. METHODS Ten days after podocin knockout, urine and faeces were collected for 10 days in metabolic cages and analysed for electrolytes, plasminogen, protease activity and ability to activate γENaC by patch clamp and western blot. Mice were treated with amiloride (2.5 mg kg-1 for 2 days and 10 mg kg-1 for 2 days) or an anti-urokinase-type plasminogen activator (uPA) targeting antibody (120 mg kg-1 /24 h) and compared to controls. RESULTS Twelve days after deletion, podocin-deficient mice developed significant protein and albuminuria associated with increased body wt, ascites, sodium accumulation and suppressed plasma renin. This was associated with increased urinary excretion of plasmin and plasminogen that correlated with albumin excretion, urine protease activity co-migrating with active plasmin, and the ability of urine to induce an amiloride-sensitive inward current in M1 cells in vitro. Amiloride treatment in podocin-deficient mice resulted in weight loss, increased sodium excretion, normalization of sodium balance and prevention of the activation of plasminogen to plasmin in urine in a reversible way. Administration of uPA targeting antibody abolished urine activation of plasminogen, attenuated sodium accumulation and prevented cleavage of γENaC. CONCLUSIONS Nephrotic range glomerular proteinuria leads to urokinase-dependent intratubular plasminogen activation and γENaC cleavage which contribute to sodium accumulation.
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Affiliation(s)
- Gitte R. Hinrichs
- Department of Molecular Medicine, Cardiovascular and Renal Research University of Southern Denmark Odense Denmark
| | - Kathrin Weyer
- Department of Biomedicine Aarhus University Aarhus Denmark
| | - Ulla G. Friis
- Department of Molecular Medicine, Cardiovascular and Renal Research University of Southern Denmark Odense Denmark
| | - Per Svenningsen
- Department of Molecular Medicine, Cardiovascular and Renal Research University of Southern Denmark Odense Denmark
| | - Ida K. Lund
- The Finsen Laboratory Rigshospitalet Copenhagen Denmark
- Biotech Research & Innovation Centre (BRIC) University of Copenhagen Copenhagen Denmark
| | - Rikke Nielsen
- Department of Biomedicine Aarhus University Aarhus Denmark
| | - Géraldine Mollet
- Laboratory of Hereditary Kidney Diseases Imagine Institute Inserm, U1163 Paris Descartes‐Sorbonne Paris Cité University Paris France
| | - Corinne Antignac
- Laboratory of Hereditary Kidney Diseases Imagine Institute Inserm, U1163 Paris Descartes‐Sorbonne Paris Cité University Paris France
- Department of Genetics Necker Hospital Assistance Publique‐Hôpitaux de Paris Paris France
| | - Claus Bistrup
- Department of Nephrology Odense University Hospital Odense Denmark
- Department of Clinical Research University of Southern Denmark Odense Denmark
| | - Boye L. Jensen
- Department of Molecular Medicine, Cardiovascular and Renal Research University of Southern Denmark Odense Denmark
| | - Henrik Birn
- Department of Biomedicine Aarhus University Aarhus Denmark
- Department of Renal Medicine Aarhus University Hospital Aarhus Denmark
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Abstract
Epithelial Na+ channels (ENaCs) are members of a family of cation channels that function as sensors of the extracellular environment. ENaCs are activated by specific proteases in the biosynthetic pathway and at the cell surface and remove embedded inhibitory tracts, which allows channels to transition to higher open-probability states. Resolved structures of ENaC and an acid-sensing ion channel revealed highly organized extracellular regions. Within the periphery of ENaC subunits are unique domains formed by antiparallel β-strands containing the inhibitory tracts and protease cleavage sites. ENaCs are inhibited by Na+ binding to specific extracellular site(s), which promotes channel transition to a lower open-probability state. Specific inositol phospholipids and channel modification by Cys-palmitoylation enhance channel open probability. How these regulatory factors interact in a concerted manner to influence channel open probability is an important question that has not been resolved. These various factors are reviewed, and the impact of specific factors on human disorders is discussed.
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Affiliation(s)
- Thomas R Kleyman
- Renal-Electrolyte Division, Department of Medicine, and Departments of Cell Biology and of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Douglas C Eaton
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, Georgia
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Mutchler SM, Kleyman TR. New insights regarding epithelial Na+ channel regulation and its role in the kidney, immune system and vasculature. Curr Opin Nephrol Hypertens 2019; 28:113-119. [PMID: 30585851 PMCID: PMC6349474 DOI: 10.1097/mnh.0000000000000479] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE OF REVIEW This review describes recent findings regarding the epithelial Na channel (ENaC) and its roles in physiologic and pathophysiologic states. We discuss new insights regarding ENaC's structure, its regulation by various factors, its potential role in hypertension and nephrotic syndrome, and its roles in the immune system and vasculature. RECENT FINDINGS A recently resolved structure of ENaC provides clues regarding mechanisms of ENaC activation by proteases. The use of amiloride in nephrotic syndrome, and associated complications are discussed. ENaC is expressed in dendritic cells and contributes to immune system activation and increases in blood pressure in response to NaCl. ENaC is expressed in endothelial ENaC and has a role in regulating vascular tone. SUMMARY New findings have emerged regarding ENaC and its role in the kidney, immune system, and vasculature.
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Affiliation(s)
- Stephanie M. Mutchler
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA
| | - Thomas R. Kleyman
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA
- Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA
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