1
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Bourgeois S, Houillier P. State of knowledge on ammonia handling by the kidney. Pflugers Arch 2024; 476:517-531. [PMID: 38448728 PMCID: PMC11006756 DOI: 10.1007/s00424-024-02940-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/28/2024] [Accepted: 03/01/2024] [Indexed: 03/08/2024]
Abstract
The disposal of ammonia, the main proton buffer in the urine, is important for acid-base homeostasis. Renal ammonia excretion is the predominant contributor to renal net acid excretion, both under basal condition and in response to acidosis. New insights into the mechanisms of renal ammonia production and transport have been gained in the past decades. Ammonia is the only urinary solute known to be produced in the kidney and selectively transported through the different parts of the nephron. Both molecular forms of total ammonia, NH3 and NH4+, are transported by specific proteins. Proximal tubular ammoniagenesis and the activity of these transport processes determine the eventual fate of total ammonia produced and excreted by the kidney. In this review, we summarized the state of the art of ammonia handling by the kidney and highlighted the newest processes described in the last decade.
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Affiliation(s)
- Soline Bourgeois
- Institut of Physiology, University of Zurich, Zurich, Switzerland.
| | - Pascal Houillier
- Centre de Recherche Des Cordeliers, INSERM, Sorbonne Université, Université Paris Cité, Paris, France
- Centre National de La Recherche Scientifique (CNRS), EMR 8228, Paris, France
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2
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Kuhn C, Mohebbi N, Ritter A. Metabolic acidosis in chronic kidney disease: mere consequence or also culprit? Pflugers Arch 2024; 476:579-592. [PMID: 38279993 PMCID: PMC11006741 DOI: 10.1007/s00424-024-02912-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/29/2024]
Abstract
Metabolic acidosis is a frequent complication in non-transplant chronic kidney disease (CKD) and after kidney transplantation. It occurs when net endogenous acid production exceeds net acid excretion. While nephron loss with reduced ammoniagenesis is the main cause of acid retention in non-transplant CKD patients, additional pathophysiological mechanisms are likely inflicted in kidney transplant recipients. Functional tubular damage by calcineurin inhibitors seems to play a key role causing renal tubular acidosis. Notably, experimental and clinical studies over the past decades have provided evidence that metabolic acidosis may not only be a consequence of CKD but also a driver of disease. In metabolic acidosis, activation of hormonal systems and the complement system resulting in fibrosis have been described. Further studies of changes in renal metabolism will likely contribute to a deeper understanding of the pathophysiology of metabolic acidosis in CKD. While alkali supplementation in case of reduced serum bicarbonate < 22 mmol/l has been endorsed by CKD guidelines for many years to slow renal functional decline, among other considerations, beneficial effects and thresholds for treatment have lately been under intense debate. This review article discusses this topic in light of the most recent results of trials assessing the efficacy of dietary and pharmacological interventions in CKD and kidney transplant patients.
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Affiliation(s)
- Christian Kuhn
- Clinic for Nephrology and Transplantation Medicine, Cantonal Hospital St. Gallen, St. Gallen, Switzerland
| | | | - Alexander Ritter
- Clinic for Nephrology and Transplantation Medicine, Cantonal Hospital St. Gallen, St. Gallen, Switzerland.
- Clinic for Nephrology, University Hospital Zurich, Zurich, Switzerland.
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3
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Verissimo T, Dalga D, Arnoux G, Sakhi I, Faivre A, Auwerx H, Bourgeois S, Paolucci D, Gex Q, Rutkowski JM, Legouis D, Wagner CA, Hall AM, de Seigneux S. PCK1 is a key regulator of metabolic and mitochondrial functions in renal tubular cells. Am J Physiol Renal Physiol 2023; 324:F532-F543. [PMID: 37102687 PMCID: PMC10202477 DOI: 10.1152/ajprenal.00038.2023] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/28/2023] [Accepted: 04/12/2023] [Indexed: 04/28/2023] Open
Abstract
Phosphoenolpyruvate carboxykinase 1 (PCK1 or PEPCK-C) is a cytosolic enzyme converting oxaloacetate to phosphoenolpyruvate, with a potential role in gluconeogenesis, ammoniagenesis, and cataplerosis in the liver. Kidney proximal tubule cells display high expression of this enzyme, whose importance is currently not well defined. We generated PCK1 kidney-specific knockout and knockin mice under the tubular cell-specific PAX8 promoter. We studied the effect of PCK1 deletion and overexpression at the renal level on tubular physiology under normal conditions and during metabolic acidosis and proteinuric renal disease. PCK1 deletion led to hyperchloremic metabolic acidosis characterized by reduced but not abolished ammoniagenesis. PCK1 deletion also resulted in glycosuria, lactaturia, and altered systemic glucose and lactate metabolism at baseline and during metabolic acidosis. Metabolic acidosis resulted in kidney injury in PCK1-deficient animals with decreased creatinine clearance and albuminuria. PCK1 further regulated energy production by the proximal tubule, and PCK1 deletion decreased ATP generation. In proteinuric chronic kidney disease, mitigation of PCK1 downregulation led to better renal function preservation. PCK1 is essential for kidney tubular cell acid-base control, mitochondrial function, and glucose/lactate homeostasis. Loss of PCK1 increases tubular injury during acidosis. Mitigating kidney tubular PCK1 downregulation during proteinuric renal disease improves renal function.NEW & NOTEWORTHY Phosphoenolpyruvate carboxykinase 1 (PCK1) is highly expressed in the proximal tubule. We show here that this enzyme is crucial for the maintenance of normal tubular physiology, lactate, and glucose homeostasis. PCK1 is a regulator of acid-base balance and ammoniagenesis. Preventing PCK1 downregulation during renal injury improves renal function, rendering it an important target during renal disease.
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Affiliation(s)
- Thomas Verissimo
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
- Department of Medicine, Service of Nephrology, Geneva University Hospitals, Geneva, Switzerland
| | - Delal Dalga
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
- Department of Medicine, Service of Nephrology, Geneva University Hospitals, Geneva, Switzerland
| | - Grégoire Arnoux
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Imene Sakhi
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Anna Faivre
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Hannah Auwerx
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Soline Bourgeois
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Deborah Paolucci
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Quentin Gex
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | | | - David Legouis
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
- Division of Intensive Care, Department of Acute Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Andrew M Hall
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
- Department of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Sophie de Seigneux
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
- Department of Medicine, Service of Nephrology, Geneva University Hospitals, Geneva, Switzerland
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4
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Nagami GT, Kraut JA. Regulation of Acid-Base Balance in Patients With Chronic Kidney Disease. Adv Chronic Kidney Dis 2022; 29:337-342. [PMID: 36175071 DOI: 10.1053/j.ackd.2022.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 05/16/2022] [Accepted: 05/31/2022] [Indexed: 01/25/2023]
Abstract
Normallly the kidneys handle the daily acid load arising from net endogenous acid production from the metabolism of ingested animal protein (acid) and vegetables (base). With chronic kidney disease, reduced acid excretion by the kidneys is primarily due to reduced ammonium excretion such that when acid excertion falls below acid porduction, acid accumulation occurs. With even mild reductions in glomerular filtration rate (60 to 90 ml/min), net acid excretion may fall below net acid production resulting in acid retention which may be initially sequestered in interstitial compartments in the kidneys, bones, and muscles resulting in no fall in measured systemic bicarbonate levels (eubicarbonatemic metabolic acidosis). With greater reductions in kidney function, the greater quantities of acid retained spillover systemically resulting in low pH (overt metabolic acidosis). The evaluation of acid-base balance in patients with CKD is complicated by the heterogeneity of clinical acid-base disorders and by the eubicarbonatemic nature of the early phase of acid retention. If supported by more extensive studies, blood gas analyses to confirm the acid-base disorder and newer ways for assessing the presence of acidosis such as urinary citrate measurements may become routine tools to evaluate and treat acid-base disorders in individuals with CKD.
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Affiliation(s)
- Glenn T Nagami
- Division of Nephrology, Department of Medicine, VA Greater Los Angeles Healthcare System, Los Angeles, CA; David Geffen School of Medicine, UCLA, Los Angeles, CA.
| | - Jeffrey A Kraut
- Division of Nephrology, VHAGLA Healthcare System, Los Angeles, CA; UCLA Membrane Biology Laboratory, David Geffen UCLA School of Medicine, Los Angeles, CA
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5
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Abstract
RNA-binding proteins (RBPs) are of fundamental importance for post-transcriptional gene regulation and protein synthesis. They are required for pre-mRNA processing and for RNA transport, degradation and translation into protein, and can regulate every step in the life cycle of their RNA targets. In addition, RBP function can be modulated by RNA binding. RBPs also participate in the formation of ribonucleoprotein complexes that build up macromolecular machineries such as the ribosome and spliceosome. Although most research has focused on mRNA-binding proteins, non-coding RNAs are also regulated and sequestered by RBPs. Functional defects and changes in the expression levels of RBPs have been implicated in numerous diseases, including neurological disorders, muscular atrophy and cancers. RBPs also contribute to a wide spectrum of kidney disorders. For example, human antigen R has been reported to have a renoprotective function in acute kidney injury (AKI) but might also contribute to the development of glomerulosclerosis, tubulointerstitial fibrosis and diabetic kidney disease (DKD), loss of bicaudal C is associated with cystic kidney diseases and Y-box binding protein 1 has been implicated in the pathogenesis of AKI, DKD and glomerular disorders. Increasing data suggest that the modulation of RBPs and their interactions with RNA targets could be promising therapeutic strategies for kidney diseases.
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6
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Vidal A, Pineda C, Raya AI, Rios R, Espartero A, Muñoz-Castañeda JR, Rodriguez M, Aguilera-Tejero E, Lopez I. Oral Acid Load Down-Regulates Fibroblast Growth Factor 23. Nutrients 2022; 14. [PMID: 35268016 DOI: 10.3390/nu14051041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/25/2022] [Accepted: 02/26/2022] [Indexed: 11/30/2022] Open
Abstract
Increased dietary acid load has a negative impact on health, particularly when renal function is compromised. Fibroblast growth factor 23 (FGF23) is a bone-derived hormone that is elevated during renal failure. The relationship between metabolic acidosis and FGF23 remains unclear. To investigate the effect of dietary acid load on circulating levels of FGF23, rats with normal renal function and with a graded reduction in renal mass (1/2 Nx and 5/6 Nx) received oral NH4Cl for 1 month. Acid intake resulted in a consistent decrease of plasma FGF23 concentrations in all study groups when compared with their non-acidotic control: 239.3 ± 13.5 vs. 295.0 ± 15.8 pg/mL (intact), 346.4 ± 19.7 vs. 522.6 ± 29.3 pg/mL (1/2 Nx) and 988.0 ± 125.5 vs. 2549.4 ± 469.7 pg/mL (5/6 Nx). Acidosis also decreased plasma PTH in all groups, 96.5 ± 22.3 vs. 107.3 ± 19.1 pg/mL, 113.1 ± 17.3 vs. 185.8 ± 22.2 pg/mL and 504.9 ± 75.7 vs. 1255.4 ± 181.1 pg/mL. FGF23 showed a strong positive correlation with PTH (r = 0.877, p < 0.0001) and further studies demonstrated that acidosis did not influence plasma FGF23 concentrations in parathyroidectomized rats, 190.0 ± 31.6 vs. 215 ± 25.6 pg/mL. In conclusion, plasma concentrations of FGF23 are consistently decreased in rats with metabolic acidosis secondary to increased acid intake, both in animals with intact renal function and with decreased renal function. The in vivo effect of metabolic acidosis on FGF23 appears to be related to the simultaneous decrease in PTH.
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7
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Faivre A, Verissimo T, Auwerx H, Legouis D, de Seigneux S. Tubular Cell Glucose Metabolism Shift During Acute and Chronic Injuries. Front Med (Lausanne) 2021; 8:742072. [PMID: 34778303 PMCID: PMC8585753 DOI: 10.3389/fmed.2021.742072] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 10/11/2021] [Indexed: 12/28/2022] Open
Abstract
Acute and chronic kidney disease are responsible for large healthcare costs worldwide. During injury, kidney metabolism undergoes profound modifications in order to adapt to oxygen and nutrient shortage. Several studies highlighted recently the importance of these metabolic adaptations in acute as well as in chronic phases of renal disease, with a potential deleterious effect on fibrosis progression. Until recently, glucose metabolism in the kidney has been poorly studied, even though the kidney has the capacity to use and produce glucose, depending on the segment of the nephron. During physiology, renal proximal tubular cells use the beta-oxidation of fatty acid to generate large amounts of energy, and can also produce glucose through gluconeogenesis. In acute kidney injury, proximal tubular cells metabolism undergo a metabolic shift, shifting away from beta-oxidation of fatty acids and gluconeogenesis toward glycolysis. In chronic kidney disease, the loss of fatty acid oxidation is also well-described, and data about glucose metabolism are emerging. We here review the modifications of proximal tubular cells glucose metabolism during acute and chronic kidney disease and their potential consequences, as well as the potential therapeutic implications.
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Affiliation(s)
- Anna Faivre
- Laboratory of Nephrology, Geneva University Hospitals, Geneva, Switzerland.,Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Thomas Verissimo
- Laboratory of Nephrology, Geneva University Hospitals, Geneva, Switzerland.,Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Hannah Auwerx
- Laboratory of Nephrology, Geneva University Hospitals, Geneva, Switzerland.,Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - David Legouis
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.,Intensive Care Unit, Department of Acute Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Sophie de Seigneux
- Laboratory of Nephrology, Geneva University Hospitals, Geneva, Switzerland.,Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
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8
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Imenez Silva PH, Unwin R, Hoorn EJ, Ortiz A, Trepiccione F, Nielsen R, Pesic V, Hafez G, Fouque D, Massy ZA, De Zeeuw CI, Capasso G, Wagner CA. Acidosis, cognitive dysfunction and motor impairments in patients with kidney disease. Nephrol Dial Transplant 2021; 37:ii4-ii12. [PMID: 34718761 PMCID: PMC8713149 DOI: 10.1093/ndt/gfab216] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Indexed: 12/20/2022] Open
Abstract
Metabolic acidosis, defined as a plasma or serum bicarbonate concentration <22 mmol/L, is a frequent consequence of chronic kidney disease (CKD) and occurs in ~10–30% of patients with advanced stages of CKD. Likewise, in patients with a kidney transplant, prevalence rates of metabolic acidosis range from 20% to 50%. CKD has recently been associated with cognitive dysfunction, including mild cognitive impairment with memory and attention deficits, reduced executive functions and morphological damage detectable with imaging. Also, impaired motor functions and loss of muscle strength are often found in patients with advanced CKD, which in part may be attributed to altered central nervous system (CNS) functions. While the exact mechanisms of how CKD may cause cognitive dysfunction and reduced motor functions are still debated, recent data point towards the possibility that acidosis is one modifiable contributor to cognitive dysfunction. This review summarizes recent evidence for an association between acidosis and cognitive dysfunction in patients with CKD and discusses potential mechanisms by which acidosis may impact CNS functions. The review also identifies important open questions to be answered to improve prevention and therapy of cognitive dysfunction in the setting of metabolic acidosis in patients with CKD.
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Affiliation(s)
- Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Zürich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Zürich, Switzerland
| | - Robert Unwin
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
| | - Ewout J Hoorn
- Department of Internal Medicine, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Alberto Ortiz
- Department of Nephrology and Hypertension, IIS-Fundacion Jimenez Diaz, Universidad Autonoma de Madrid, Madrid, Spain
| | - Francesco Trepiccione
- Biogem Institute of Molecular Biology and Genetics, Ariano Irpino, Italy.,Department of Translational Medical Sciences, University of Campania "Luigi Vanvitelli," Naples, Italy
| | - Rikke Nielsen
- Department of Biomedicine-Anatomy, University of Aarhus, Aarhus, Denmark
| | - Vesna Pesic
- Department of Physiology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia
| | - Gaye Hafez
- Department of Pharmacology, Faculty of Pharmacy, Altinbas University, Istanbul, Turkey
| | - Denis Fouque
- CarMeN, INSERM 1060, Université Claude Bernard Lyon 1, Lyon, France.,Service de Néphrologie, Lyon-Sud Hospital, Pierre-Bénite, France
| | - Ziad A Massy
- Department of Nephrology, Ambroise Paré University Hospital, Assistance Publique Hôpitaux de Paris, Boulogne-Billancourt, France.,Centre de Recherche en Epidémiologie et Santé des Populations, Institut National de la Santé et de la Recherche Médicale U1018-Team 5, Université de Versailles Saint-Quentin-en-Yvelines, University Paris Saclay, Villejuif, France
| | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, The Netherlands.,Netherlands Institute for Neuroscience, Royal Dutch Academy of Art and Science, Amsterdam, The Netherlands
| | - Giovambattista Capasso
- Biogem Institute of Molecular Biology and Genetics, Ariano Irpino, Italy.,Department of Translational Medical Sciences, University of Campania "Luigi Vanvitelli," Naples, Italy
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zürich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Zürich, Switzerland
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9
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Silva PHI, Wiegand A, Daryadel A, Russo G, Ritter A, Gaspert A, Wüthrich RP, Wagner CA, Mohebbi N. Acidosis and alkali therapy in patients with kidney transplant is associated with transcriptional changes and altered abundance of genes involved in cell metabolism and acid-base balance. Nephrol Dial Transplant 2021; 36:1806-1820. [PMID: 34240183 DOI: 10.1093/ndt/gfab210] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Metabolic acidosis occurs frequently in patients with kidney transplant and is associated with higher risk for and accelerated loss of graft function. To date, it is not known whether alkali therapy in these patients improves kidney function and whether acidosis and its therapy is associated with altered expression of proteins involved in renal acid-base metabolism. METHODS We collected retrospectively kidney biopsies from 22 patients. Of these patients, 9 had no acidosis, 9 had metabolic acidosis (plasma HCO3- < 22 mmol/l), and 4 had acidosis and received alkali therapy. We performed transcriptome analysis and immunohistochemistry for proteins involved in renal acid-base handling. RESULTS We found the expression of 40 transcripts significantly changed between kidneys from non-acidotic and acidotic patients. These genes are mostly involved in proximal tubule amino acid and lipid metabolism and energy homeostasis. Three transcripts were fully recovered by alkali therapy: the Kir4.2 K+-channel, an important regulator of proximal tubule HCO3--metabolism and transport, ACADSB and SHMT1, genes involved in beta-oxidation and methionine metabolism. Immunohistochemistry showed reduced staining for the proximal tubule NBCe1 HCO3- transporter in kidneys from acidotic patients that recovered with alkali therapy. In addition, the HCO3-exchanger pendrin was affected by acidosis and alkali therapy. CONCLUSIONS Metabolic acidosis in kidney transplant recipients is associated with alterations in the renal transcriptome that are partly restored by alkali therapy. Acid-base transport proteins mostly from proximal tubule were also affected by acidosis and alkali therapy suggesting that the downregulation of critical players contributes to metabolic acidosis in these patients.
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Affiliation(s)
- Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
| | - Anna Wiegand
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Arezoo Daryadel
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
| | - Giancarlo Russo
- Functional Genomics Center Zürich, University of Zürich and ETH Zürich, Zürich, Switzerland
| | - Alexander Ritter
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Ariana Gaspert
- Department of Pathology and Molecular Pathology, University Hospital Zurich, Zurich, Switzerland
| | - Rudolf P Wüthrich
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research NCCR Kidney.CH, Switzerland
| | - Nilufar Mohebbi
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
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10
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Eguchi K, Izumi Y, Yasuoka Y, Nakagawa T, Ono M, Maruyama K, Matsuo N, Hiramatsu A, Inoue H, Nakayama Y, Nonoguchi H, Lee HW, Weiner ID, Kakizoe Y, Kuwabara T, Mukoyama M. Regulation of Rhcg, an ammonia transporter, by aldosterone in the kidney. J Endocrinol 2021; 249:95-112. [PMID: 33705345 PMCID: PMC9428946 DOI: 10.1530/joe-20-0267] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 03/09/2021] [Indexed: 11/08/2022]
Abstract
Rhesus C glycoprotein (Rhcg), an ammonia transporter, is a key molecule in urinary acid excretion and is expressed mainly in the intercalated cells (ICs) of the renal collecting duct. In the present study we investigated the role of aldosterone in the regulation of Rhcg expression. In in vivo experiments using C57BL/6J mice, Western blot analysis showed that continuous subcutaneous administration of aldosterone increased the expression of Rhcg in membrane fraction of the kidney. Supplementation of potassium inhibited the effect of aldosterone on the Rhcg. Next, mice were subjected to adrenalectomy with or without administration of aldosterone, and then ad libitum 0.14 M NH4Cl containing water was given. NH4Cl load increased the expression of Rhcg in membrane fraction. Adrenalectomy decreased NH4Cl-induced Rhcg expression, which was restored by administration of aldosterone. Immunohistochemical studies revealed that NH4Cl load induced the localization of Rhcg at the apical membrane of ICs in the outer medullary collecting duct. Adrenalectomy decreased NH4Cl-induced membrane localization of Rhcg, which was restored by administration of aldosterone. For in vitro experiments, IN-IC cells, an immortalized cell line stably expressing Flag-tagged Rhcg (Rhcg-Flag), were used. Western blot analysis showed that aldosterone increased the expression of Rhcg-Flag in membrane fraction, while the increase in extracellular potassium level inhibited the effect of aldosterone. Both spironolactone and Gӧ6983, a PKC inhibitor, inhibited the expression of Rhcg-Flag in the membrane fraction. These results suggest that aldosterone regulates the membrane expression of Rhcg through the mineralocorticoid receptor and PKC pathways, which is modulated by extracellular potassium level.
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Affiliation(s)
- Koji Eguchi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Chuo-ku, Kumamoto, Japan
| | - Yuichiro Izumi
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Chuo-ku, Kumamoto, Japan
| | - Yukiko Yasuoka
- Department of Physiology, Kitasato University School of Medicine, Minami-ku, Sagamihara, Kanagawa, Japan
| | - Terumasa Nakagawa
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Chuo-ku, Kumamoto, Japan
| | - Makoto Ono
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Chuo-ku, Kumamoto, Japan
| | - Kosuke Maruyama
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Chuo-ku, Kumamoto, Japan
| | - Naomi Matsuo
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Chuo-ku, Kumamoto, Japan
| | - Akiko Hiramatsu
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Chuo-ku, Kumamoto, Japan
| | - Hideki Inoue
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Chuo-ku, Kumamoto, Japan
| | - Yushi Nakayama
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Chuo-ku, Kumamoto, Japan
| | - Hiroshi Nonoguchi
- Division of Internal Medicine, Kitasato University Medical Center, Kitamoto, Saitama, Japan
| | - Hyun-Wook Lee
- Division of Nephrology, Hypertension, and Transplantation, University of Florida College of Medicine, Gainesville, Florida, USA
| | - I David Weiner
- Division of Nephrology, Hypertension, and Transplantation, University of Florida College of Medicine, Gainesville, Florida, USA
- Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, Florida, USA
| | - Yutaka Kakizoe
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Chuo-ku, Kumamoto, Japan
| | - Takashige Kuwabara
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Chuo-ku, Kumamoto, Japan
| | - Masashi Mukoyama
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Chuo-ku, Kumamoto, Japan
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11
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Ritter A, Mohebbi N. Causes and Consequences of Metabolic Acidosis in Patients after Kidney Transplantation. Kidney Blood Press Res 2020; 45:792-801. [PMID: 33040055 DOI: 10.1159/000510158] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 07/01/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Metabolic acidosis (MA) is a common complication in kidney transplantation (KTx). It is more prevalent in KTx than in CKD, and it occurs at higher glomerular filtration rates. The pathophysiologic understanding of MA in KTx and its clinical impact has been highlighted by few recent studies. However, no guidelines exist yet for the treatment of MA after KTx. SUMMARY MA in KTx seems to share pathophysiologic mechanisms with CKD, such as impaired ammoniagenesis. Additional kidney transplant-specific factors seem to alter not only the prevalence but also the phenotype of MA, which typically shows features of renal tubular acidosis. There is evidence that calcineurin inhibitors, immunological factors, process of donation, donor characteristics, and diet may contribute to MA occurrence. According to several mainly observational studies, MA seems to play a role in disturbed bone metabolism, cardiovascular morbidity, declining graft function, and mortality. A better understanding of the pathophysiology and evidence from randomized controlled trials, in particular, are needed to clarify the role of MA and the potential benefit of alkali treatment in KTx. Alkali therapy might not only be beneficial but also cost effective and safe. Key Messages: MA seems to be associated with several negative outcomes in KTx. A deeper understanding of the pathophysiology and clinical consequences of MA in KTx is crucial. Clinical trials will have to determine the potential benefits of alkali therapy.
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Affiliation(s)
- Alexander Ritter
- Division of Nephrology, University Hospital of Zurich, Zurich, Switzerland
| | - Nilufar Mohebbi
- Division of Nephrology, University Hospital of Zurich, Zurich, Switzerland, .,Praxis und Dialysezentrum Zürich-City, Zurich, Switzerland,
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12
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Alam P, Amlal S, Thakar CV, Amlal H. Acetazolamide causes renal [Formula: see text] wasting but inhibits ammoniagenesis and prevents the correction of metabolic acidosis by the kidney. Am J Physiol Renal Physiol 2020; 319:F366-F379. [PMID: 32657159 PMCID: PMC7509283 DOI: 10.1152/ajprenal.00501.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 07/05/2020] [Accepted: 07/06/2020] [Indexed: 11/22/2022] Open
Abstract
Carbonic anhydrase (CAII) binds to the electrogenic basolateral Na+-[Formula: see text] cotransporter (NBCe1) and facilitates [Formula: see text] reabsorption across the proximal tubule. However, whether the inhibition of CAII with acetazolamide (ACTZ) alters NBCe1 activity and interferes with the ammoniagenesis pathway remains elusive. To address this issue, we compared the renal adaptation of rats treated with ACTZ to NH4Cl loading for up to 2 wk. The results indicated that ACTZ-treated rats exhibited a sustained metabolic acidosis for up to 2 wk, whereas in NH4Cl-loaded rats, metabolic acidosis was corrected within 2 wk of treatment. [Formula: see text] excretion increased by 10-fold in NH4Cl-loaded rats but only slightly (1.7-fold) in ACTZ-treated rats during the first week despite a similar degree of acidosis. Immunoblot experiments showed that the protein abundance of glutaminase (4-fold), glutamate dehydrogenase (6-fold), and SN1 (8-fold) increased significantly in NH4Cl-loaded rats but remained unchanged in ACTZ-treated rats. Na+/H+ exchanger 3 and NBCe1 proteins were upregulated in response to NH4Cl loading but not ACTZ treatment and were rather sharply downregulated after 2 wk of ACTZ treatment. ACTZ causes renal [Formula: see text] wasting and induces metabolic acidosis but inhibits the upregulation of glutamine transporter and ammoniagenic enzymes and thus suppresses ammonia synthesis and secretion in the proximal tubule, which prevented the correction of acidosis. This effect is likely mediated through the inhibition of the CA-NBCe1 metabolon complex, which results in cell alkalinization. During chronic ACTZ treatment, the downregulation of both NBCe1 and Na+/H+ exchanger 3, along with the inhibition of ammoniagenesis and [Formula: see text] generation, contributes to the maintenance of metabolic acidosis.
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Affiliation(s)
- Perwez Alam
- Division of Nephrology and Kidney C.A.R.E, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
- Department of Pathology and Laboratory Medicine, College of Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Sihame Amlal
- Division of Nephrology and Kidney C.A.R.E, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Charuhas V Thakar
- Division of Nephrology and Kidney C.A.R.E, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Hassane Amlal
- Division of Nephrology and Kidney C.A.R.E, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
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13
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Herrmann SM, Alexander MP, Romero MF, Zand L. Renal Tubular Acidosis and Immune Checkpoint Inhibitor Therapy: An Immune-Related Adverse Event of PD-1 Inhibitor-A Report of 3 Cases. Kidney Med 2020; 2:657-662. [PMID: 33089143 PMCID: PMC7568062 DOI: 10.1016/j.xkme.2020.05.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The main cause of acute kidney injury in patients receiving immune checkpoint inhibitors (ICIs) is acute interstitial nephritis. However, as their use continues to increase, other kidney manifestations are being described. We report 3 cases of patients treated with ICIs who developed predominantly electrolyte disorders secondary to renal tubular acidosis as an immune-related adverse event and discuss the potential mechanism. Nongap acidosis in combination with hypokalemia should raise suspicion for distal renal tubular acidosis in patients treated with ICIs.
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Affiliation(s)
- Sandra M Herrmann
- Divisions of Nephrology and Hypertension, Mayo Clinic, Rochester, MN
| | | | - Michael F Romero
- Divisions of Nephrology and Hypertension, Mayo Clinic, Rochester, MN.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN
| | - Ladan Zand
- Divisions of Nephrology and Hypertension, Mayo Clinic, Rochester, MN
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14
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Tu J, Zhang B, Fang G, Chang W, Zhao Y. Neddylation-mediated Nedd4-2 activation regulates ubiquitination modification of renal NBCe1. Exp Cell Res 2020; 390:111958. [DOI: 10.1016/j.yexcr.2020.111958] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 03/10/2020] [Accepted: 03/11/2020] [Indexed: 12/11/2022]
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15
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Abstract
Ammonia metabolism has a critical role in acid-base homeostasis and in other cellular functions. Kidneys have a central role in bicarbonate generation, which occurs through the process of net acid excretion; ammonia metabolism is the quantitatively greatest component of net acid excretion, both under basal conditions and in response to acid-base disturbances. Several recent studies have advanced our understanding substantially of the molecular mechanisms and regulation of ammonia metabolism. First, the previous paradigm that ammonia transport could be explained by passive NH3 diffusion and NH4+ trapping has been advanced by the recognition that specific transport of NH3 and of NH4+ by specific membrane proteins is critical to ammonia transport. Second, significant advances have been made in the understanding of the regulation of ammonia metabolism. Novel studies have shown that hyperkalemia directly inhibits ammonia metabolism, thereby leading to the metabolic acidosis present in type IV renal tubular acidosis. Other studies have shown that the proximal tubule protein NBCe1, specifically the A variant NBCe1-A, has a major role in regulating renal ammonia metabolism. Third, there are important sex differences in ammonia metabolism that involve structural and functional differences in the kidney. This review addresses these important aspects of ammonia metabolism and transport.
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Affiliation(s)
- I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, FL; Nephrology and Hypertension Section, Gainesville Veterans Affairs Medical Center, Gainesville, FL.
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, FL
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16
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Abstract
Acid-base balance is critical for normal life. Acute and chronic disturbances impact cellular energy metabolism, endocrine signaling, ion channel activity, neuronal activity, and cardiovascular functions such as cardiac contractility and vascular blood flow. Maintenance and adaptation of acid-base homeostasis are mostly controlled by respiration and kidney. The kidney contributes to acid-base balance by reabsorbing filtered bicarbonate, regenerating bicarbonate through ammoniagenesis and generation of protons, and by excreting acid. This review focuses on acid-base disorders caused by renal processes, both inherited and acquired. Distinct rare inherited monogenic diseases affecting acid-base handling in the proximal tubule and collecting duct have been identified. In the proximal tubule, mutations of solute carrier 4A4 (SLC4A4) (electrogenic Na+/HCO3--cotransporter Na+/bicarbonate cotransporter e1 [NBCe1]) and other genes such as CLCN5 (Cl-/H+-antiporter), SLC2A2 (GLUT2 glucose transporter), or EHHADH (enoyl-CoA, hydratase/3-hydroxyacyl CoA dehydrogenase) causing more generalized proximal tubule dysfunction can cause proximal renal tubular acidosis resulting from bicarbonate wasting and reduced ammoniagenesis. Mutations in adenosine triphosphate ATP6V1 (B1 H+-ATPase subunit), ATPV0A4 (a4 H+-ATPase subunit), SLC4A1 (anion exchanger 1), and FOXI1 (forkhead transcription factor) cause distal renal tubular acidosis type I. Carbonic anhydrase II mutations affect several nephron segments and give rise to a mixed proximal and distal phenotype. Finally, mutations in genes affecting aldosterone synthesis, signaling, or downstream targets can lead to hyperkalemic variants of renal tubular acidosis (type IV). More common forms of renal acidosis are found in patients with advanced stages of chronic kidney disease and are owing, at least in part, to a reduced capacity for ammoniagenesis.
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Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center for Competence in Research Kidney, Switzerland.
| | - Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center for Competence in Research Kidney, Switzerland
| | - Soline Bourgeois
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center for Competence in Research Kidney, Switzerland
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17
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Abstract
A large body of work in animals and human beings supports the hypothesis that metabolic acidosis has a deleterious effect on the progression of kidney disease. Alkali therapy, whether pharmacologically or through dietary intervention, appears to slow CKD progression, but an appropriately powered randomized controlled trial with a low risk of bias is required to reach a more definitive conclusion. Recent work on urinary ammonium excretion has shown that the development of prognostic tools related to acidosis is not straightforward, and that application of urine markers such as ammonium may require more nuance than would be predicted based on our understanding of the pathophysiology.
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Affiliation(s)
- Wei Chen
- Department of Medicine, Nephrology Division, Albert Einstein College of Medicine, Bronx, NY; Department of Medicine, Nephrology Division, University of Rochester School of Medicine and Dentistry, Rochester, NY.
| | - David S Levy
- Department of Medicine, Nephrology Division, University of Rochester School of Medicine and Dentistry, Rochester, NY
| | - Matthew K Abramowitz
- Department of Medicine, Nephrology Division, Albert Einstein College of Medicine, Bronx, NY
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18
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Kandasamy P, Gyimesi G, Kanai Y, Hediger MA. Amino acid transporters revisited: New views in health and disease. Trends Biochem Sci 2018; 43:752-789. [PMID: 30177408 DOI: 10.1016/j.tibs.2018.05.003] [Citation(s) in RCA: 247] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 05/23/2018] [Accepted: 05/25/2018] [Indexed: 02/09/2023]
Abstract
Amino acid transporters (AATs) are membrane-bound transport proteins that mediate transfer of amino acids into and out of cells or cellular organelles. AATs have diverse functional roles ranging from neurotransmission to acid-base balance, intracellular energy metabolism, and anabolic and catabolic reactions. In cancer cells and diabetes, dysregulation of AATs leads to metabolic reprogramming, which changes intracellular amino acid levels, contributing to the pathogenesis of cancer, obesity and diabetes. Indeed, the neutral amino acid transporters (NATs) SLC7A5/LAT1 and SLC1A5/ASCT2 are likely involved in several human malignancies. However, a clinical therapy that directly targets AATs has not yet been developed. The purpose of this review is to highlight the structural and functional diversity of AATs, their diverse physiological roles in different tissues and organs, their wide-ranging implications in human diseases and the emerging strategies and tools that will be necessary to target AATs therapeutically.
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Affiliation(s)
- Palanivel Kandasamy
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, CH-3012 Bern, Switzerland
| | - Gergely Gyimesi
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, CH-3012 Bern, Switzerland
| | - Yoshikatsu Kanai
- Division of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan.
| | - Matthias A Hediger
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bühlstrasse 28, CH-3012 Bern, Switzerland.
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19
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Lister A, Bourgeois S, Imenez Silva PH, Rubio-Aliaga I, Marbet P, Walsh J, Shelton LM, Keller B, Verrey F, Devuyst O, Giesbertz P, Daniel H, Goldring CE, Copple IM, Wagner CA, Odermatt A. NRF2 regulates the glutamine transporter Slc38a3 (SNAT3) in kidney in response to metabolic acidosis. Sci Rep 2018; 8:5629. [PMID: 29618784 PMCID: PMC5884861 DOI: 10.1038/s41598-018-24000-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 03/19/2018] [Indexed: 12/28/2022] Open
Abstract
Expression of the glutamine transporter SNAT3 increases in kidney during metabolic acidosis, suggesting a role during ammoniagenesis. Microarray analysis of Nrf2 knock-out (KO) mouse kidney identified Snat3 as the most significantly down-regulated transcript compared to wild-type (WT). We hypothesized that in the absence of NRF2 the kidney would be unable to induce SNAT3 under conditions of metabolic acidosis and therefore reduce the availability of glutamine for ammoniagenesis. Metabolic acidosis was induced for 7 days in WT and Nrf2 KO mice. Nrf2 KO mice failed to induce Snat3 mRNA and protein expression during metabolic acidosis. However, there were no differences in blood pH, bicarbonate, pCO2, chloride and calcium or urinary pH, ammonium and phosphate levels. Normal induction of ammoniagenic enzymes was observed whereas several amino acid transporters showed differential regulation. Moreover, Nrf2 KO mice during acidosis showed increased expression of renal markers of oxidative stress and injury and NRF2 activity was increased during metabolic acidosis in WT kidney. We conclude that NRF2 is required to adapt the levels of SNAT3 in response to metabolic acidosis. In the absence of NRF2 and SNAT3, the kidney does not have any major acid handling defect; however, increased oxidative stress and renal injury may occur.
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Affiliation(s)
- Adam Lister
- Department of Pharmaceutical Sciences, Division of Molecular and Systems Toxicology, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Soline Bourgeois
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Pedro H Imenez Silva
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Isabel Rubio-Aliaga
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Philippe Marbet
- Department of Pharmaceutical Sciences, Division of Molecular and Systems Toxicology, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Joanne Walsh
- Department of Molecular and Clinical Pharmacology, MRC Centre for Drug Safety Science, University of Liverpool, Liverpool, L69 3GE, UK
| | - Luke M Shelton
- Department of Molecular and Clinical Pharmacology, MRC Centre for Drug Safety Science, University of Liverpool, Liverpool, L69 3GE, UK
| | - Bettina Keller
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland
| | - Francois Verrey
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Olivier Devuyst
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland.,National Center for Competence in Research Kidney.CH, Zürich, Switzerland
| | - Pieter Giesbertz
- Department of Biochemistry, ZIEL Research Center of Nutrition and Food Sciences, Technische Universität München, Freising, Germany
| | - Hannelore Daniel
- Department of Biochemistry, ZIEL Research Center of Nutrition and Food Sciences, Technische Universität München, Freising, Germany
| | - Christopher E Goldring
- Department of Molecular and Clinical Pharmacology, MRC Centre for Drug Safety Science, University of Liverpool, Liverpool, L69 3GE, UK
| | - Ian M Copple
- Department of Molecular and Clinical Pharmacology, MRC Centre for Drug Safety Science, University of Liverpool, Liverpool, L69 3GE, UK
| | - Carsten A Wagner
- Institute of Physiology, Zürich Centre for Integrative Human Physiology, University of Zürich, Winterthurerstrasse 190, 8057, Zürich, Switzerland. .,National Center for Competence in Research Kidney.CH, Zürich, Switzerland.
| | - Alex Odermatt
- Department of Pharmaceutical Sciences, Division of Molecular and Systems Toxicology, University of Basel, Klingelbergstrasse 50, 4056, Basel, Switzerland. .,National Center for Competence in Research Kidney.CH, Zürich, Switzerland.
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20
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Araya S, Kuster E, Gluch D, Mariotta L, Lutz C, Reding TV, Graf R, Verrey F, Camargo SMR. Exocrine pancreas glutamate secretion help to sustain enterocyte nutritional needs under protein restriction. Am J Physiol Gastrointest Liver Physiol 2018; 314:G517-G536. [PMID: 29167114 DOI: 10.1152/ajpgi.00135.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Glutamine (Gln) is the most concentrated amino acid in blood and considered conditionally essential. Its requirement is increased during physiological stress, such as malnutrition or illness, despite its production by muscle and other organs. In the malnourished state, Gln has been suggested to have a trophic effect on the exocrine pancreas and small intestine. However, the Gln transport capacity, the functional relationship of these two organs, and the potential role of the Gln-glutamate (Glu) cycle are unknown. We observed that pancreatic acinar cells express lower levels of Glu than Gln transporters. Consistent with this expression pattern, the rate of Glu influx into acinar cells was approximately sixfold lower than that of Gln. During protein restriction, acinar cell glutaminase expression was increased and Gln accumulation was maintained. Moreover, Glu secretion by acinar cells into pancreatic juice and thus into the lumen of the small intestine was maintained. In the intestinal lumen, Glu absorption was preserved and Glu dehydrogenase expression was augmented, potentially providing the substrates for increasing energy production via the TCA cycle. Our findings suggest that one mechanism by which Gln exerts a positive effect on exocrine pancreas and small intestine involves the Gln metabolism in acinar cells and the secretion of Glu into the small intestine lumen. The exocrine pancreas acinar cells not only avidly accumulate Gln but metabolize Gln to generate energy and to synthesize Glu for secretion in the pancreatic juice. Secreted Glu is suggested to play an important role during malnourishment in sustaining small intestinal homeostasis. NEW & NOTEWORTHY Glutamine (Gln) has been suggested to have a trophic effect on exocrine pancreas and small intestine in malnourished states, but the mechanism is unknown. In this study, we suggest that this trophic effect derives from an interorgan relationship between exocrine pancreas and small intestine for Gln-glutamate (Glu) utilization involving the uptake and metabolism of Gln in acinar cells and secretion of Glu into the lumen of the small intestine.
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Affiliation(s)
- S Araya
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich , Zurich , Switzerland
| | - E Kuster
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich , Zurich , Switzerland
| | - D Gluch
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich , Zurich , Switzerland
| | - L Mariotta
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich , Zurich , Switzerland
| | - C Lutz
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich , Zurich , Switzerland
| | - T V Reding
- Department of Surgery, University Hospital Zurich , Zurich , Switzerland
| | - R Graf
- Department of Surgery, University Hospital Zurich , Zurich , Switzerland
| | - F Verrey
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich , Zurich , Switzerland
| | - S M R Camargo
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich , Zurich , Switzerland
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21
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Hallan S, Afkarian M, Zelnick LR, Kestenbaum B, Sharma S, Saito R, Darshi M, Barding G, Raftery D, Ju W, Kretzler M, Sharma K, de Boer IH. Metabolomics and Gene Expression Analysis Reveal Down-regulation of the Citric Acid (TCA) Cycle in Non-diabetic CKD Patients. EBioMedicine 2017; 26:68-77. [PMID: 29128444 PMCID: PMC5832558 DOI: 10.1016/j.ebiom.2017.10.027] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/27/2017] [Accepted: 10/28/2017] [Indexed: 01/17/2023] Open
Abstract
Chronic kidney disease (CKD) is a public health problem with very high prevalence and mortality. Yet, there is a paucity of effective treatment options, partly due to insufficient knowledge of underlying pathophysiology. We combined metabolomics (GCMS) with kidney gene expression studies to identify metabolic pathways that are altered in adults with non-diabetic stage 3-4 CKD versus healthy adults. Urinary excretion rate of 27 metabolites and plasma concentration of 33 metabolites differed significantly in CKD patients versus controls (estimate range-68% to +113%). Pathway analysis revealed that the citric acid cycle was the most significantly affected, with urinary excretion of citrate, cis-aconitate, isocitrate, 2-oxoglutarate and succinate reduced by 40-68%. Reduction of the citric acid cycle metabolites in urine was replicated in an independent cohort. Expression of genes regulating aconitate, isocitrate, 2-oxoglutarate and succinate were significantly reduced in kidney biopsies. We observed increased urine citrate excretion (+74%, p=0.00009) and plasma 2-oxoglutarate concentrations (+12%, p=0.002) in CKD patients during treatment with a vitamin-D receptor agonist in a randomized trial. In conclusion, urinary excretion of citric acid cycle metabolites and renal expression of genes regulating these metabolites were reduced in non-diabetic CKD. This supports the emerging view of CKD as a state of mitochondrial dysfunction.
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Affiliation(s)
- Stein Hallan
- Center for Renal Translational Medicine/Institute for Metabolomic Medicine, University of California San Diego, San Diego, CA, United States; Department of Clinical and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway; Department of Nephrology, St. Olav Hospital, Trondheim, Norway.
| | - Maryam Afkarian
- Kidney Research Institute, University of Washington, Seattle, WA, United States; Division of Nephrology, Department of Medicine, University of California, Davis, CA, United States
| | - Leila R Zelnick
- Kidney Research Institute, University of Washington, Seattle, WA, United States; Division of Nephrology, Department of Medicine, University of Washington, Seattle, WA, United States
| | - Bryan Kestenbaum
- Kidney Research Institute, University of Washington, Seattle, WA, United States; Division of Nephrology, Department of Medicine, University of Washington, Seattle, WA, United States
| | - Shoba Sharma
- University of Texas Health San Antonio, San Antonio, TX, United States
| | - Rintaro Saito
- Center for Renal Translational Medicine/Institute for Metabolomic Medicine, University of California San Diego, San Diego, CA, United States
| | - Manjula Darshi
- Center for Renal Translational Medicine/Institute for Metabolomic Medicine, University of California San Diego, San Diego, CA, United States
| | - Gregory Barding
- Northwest Metabolomics Research Center, University of Washington, Seattle, WA, United States
| | - Daniel Raftery
- Northwest Metabolomics Research Center, University of Washington, Seattle, WA, United States
| | - Wenjun Ju
- Division of Nephrology, Department of Medicine, University of Michigan, Ann Arbor, MI, United States; Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, United States
| | - Matthias Kretzler
- Division of Nephrology, Department of Medicine, University of Michigan, Ann Arbor, MI, United States; Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, United States
| | - Kumar Sharma
- Center for Renal Translational Medicine/Institute for Metabolomic Medicine, University of California San Diego, San Diego, CA, United States; Department of Nephrology and Hypertension, Veterans Administration San Diego HealthCare System, San Diego, CA, United States
| | - Ian H de Boer
- Kidney Research Institute, University of Washington, Seattle, WA, United States; Division of Nephrology, Department of Medicine, University of Washington, Seattle, WA, United States
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22
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Mohebbi N, Wagner CA. Pathophysiology, diagnosis and treatment of inherited distal renal tubular acidosis. J Nephrol 2018; 31:511-22. [DOI: 10.1007/s40620-017-0447-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 09/21/2017] [Indexed: 10/18/2022]
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23
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Nagami GT, Hamm LL. Regulation of Acid-Base Balance in Chronic Kidney Disease. Adv Chronic Kidney Dis 2017; 24:274-279. [PMID: 29031353 DOI: 10.1053/j.ackd.2017.07.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 07/28/2017] [Indexed: 11/11/2022]
Abstract
The kidneys play a major role in the regulation of acid-base balance by reabsorbing bicarbonate filtered by the glomeruli and excreting titratable acids and ammonia into the urine. In CKD, with declining kidney function, acid retention and metabolic acidosis occur, but the extent of acid retention depends not only on the degree of kidney impairment but also on the dietary acid load. Acid retention can occur even when the serum bicarbonate level is apparently normal. With reduced kidney function, acid transport processes in the surviving nephrons are augmented but as disease progresses ammonia excretion and, in some individuals, the ability to reabsorb bicarbonate falls, whereas titratable acid excretion is preserved until kidney function is severely impaired. Urinary ammonia levels are used to gauge the renal response to acid loads and are best assessed by direct measurement of urinary ammonia levels rather than by indirect assessments. In individuals with acidosis from CKD, an inappropriately low degree of ammonia excretion points to the pathogenic role of impaired urinary acid excretion. The presence of a normal bicarbonate level in CKD complicates the interpretation of the urinary ammonia excretion as such individuals could be in acid-base balance or could be retaining acid without manifesting a low bicarbonate level. At this time, the decision to give bicarbonate supplementation in CKD is reserved for those with a bicarbonate level of 22 mEq/L, but because of potential harm of overtreatment, supplementation should be adjusted to maintain a bicarbonate level of <26 mEq/L.
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24
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Khairallah P, Isakova T, Asplin J, Hamm L, Dobre M, Rahman M, Sharma K, Leonard M, Miller E, Jaar B, Brecklin C, Yang W, Wang X, Feldman H, Wolf M, Scialla JJ. Acid Load and Phosphorus Homeostasis in CKD. Am J Kidney Dis 2017. [PMID: 28645705 DOI: 10.1053/j.ajkd.2017.04.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND The kidneys maintain acid-base homeostasis through excretion of acid as either ammonium or as titratable acids that primarily use phosphate as a buffer. In chronic kidney disease (CKD), ammoniagenesis is impaired, promoting metabolic acidosis. Metabolic acidosis stimulates phosphaturic hormones, parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF-23) in vitro, possibly to increase urine titratable acid buffers, but this has not been confirmed in humans. We hypothesized that higher acid load and acidosis would associate with altered phosphorus homeostasis, including higher urinary phosphorus excretion and serum PTH and FGF-23. STUDY DESIGN Cross-sectional. SETTING & PARTICIPANTS 980 participants with CKD enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study. PREDICTORS Net acid excretion as measured in 24-hour urine, potential renal acid load (PRAL) estimated from food frequency questionnaire responses, and serum bicarbonate concentration < 22 mEq/L. OUTCOME & MEASUREMENTS 24-hour urine phosphorus and calcium excretion and serum phosphorus, FGF-23, and PTH concentrations. RESULTS Using linear and log-linear regression adjusted for demographics, kidney function, comorbid conditions, body mass index, diuretic use, and 24-hour urine creatinine excretion, we found that 24-hour urine phosphorus excretion was higher at higher net acid excretion, higher PRAL, and lower serum bicarbonate concentration (each P<0.05). Serum phosphorus concentration was also higher with higher net acid excretion and lower serum bicarbonate concentration (each P=0.001). Only higher net acid excretion associated with higher 24-hour urine calcium excretion (P<0.001). Neither net acid excretion nor PRAL was associated with FGF-23 or PTH concentrations. PTH, but not FGF-23, concentration (P=0.2) was 26% (95% CI, 13%-40%) higher in participants with a serum bicarbonate concentration <22 versus ≥22 mEq/L (P<0.001). Primary results were similar if stratified by estimated glomerular filtration rate categories or adjusted for iothalamate glomerular filtration rate (n=359), total energy intake, dietary phosphorus, or urine urea nitrogen excretion, when available. LIMITATIONS Possible residual confounding by kidney function or nutrition; urine phosphorus excretion was included in calculation of the titratable acid component of net acid excretion. CONCLUSIONS In CKD, higher acid load and acidosis associate independently with increased circulating phosphorus concentration and augmented phosphaturia, but not consistently with FGF-23 or PTH concentrations. This may be an adaptation that increases titratable acid excretion and thus helps maintain acid-base homeostasis in CKD. Understanding whether administration of base can lower phosphorus concentrations requires testing in interventional trials.
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Affiliation(s)
| | - Tamara Isakova
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL; Center for Translational Metabolism and Health, Institute of Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - John Asplin
- Litholink Corp, Laboratory Corporation of America Holdings, Chicago, IL
| | - Lee Hamm
- Department of Medicine, Tulane University School of Medicine, New Orleans, LA
| | - Mirela Dobre
- Department of Medicine, Case Western Reserve University, Cleveland, OH
| | - Mahboob Rahman
- Department of Medicine, Case Western Reserve University, Cleveland, OH
| | - Kumar Sharma
- Department of Medicine, University of San Diego, San Diego, CA
| | - Mary Leonard
- Department of Pediatrics, Stanford University School of Medicine, Palo Alto, CA
| | - Edgar Miller
- Department of Medicine, Prevention and Clinical Research, Johns Hopkins University, Baltimore, MD; Welch Center for Epidemiology, Prevention and Clinical Research, Johns Hopkins University, Baltimore, MD
| | - Bernard Jaar
- Department of Medicine, Prevention and Clinical Research, Johns Hopkins University, Baltimore, MD; Welch Center for Epidemiology, Prevention and Clinical Research, Johns Hopkins University, Baltimore, MD; Nephrology Center of Maryland, Baltimore, MD
| | - Carolyn Brecklin
- Department of Medicine, University of Illinois at Chicago, Chicago, IL
| | - Wei Yang
- Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | - Xue Wang
- Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | - Harold Feldman
- Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA; Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA
| | - Myles Wolf
- Department of Medicine, Duke University School of Medicine, Durham, NC
| | - Julia J Scialla
- Department of Medicine, Duke University School of Medicine, Durham, NC; Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC; Department of Medicine, Durham Veterans Affairs Medical Center, Durham, NC.
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Abstract
Acid-base homeostasis is critical to maintenance of normal health. Renal ammonia excretion is the quantitatively predominant component of renal net acid excretion, both under basal conditions and in response to acid-base disturbances. Although titratable acid excretion also contributes to renal net acid excretion, the quantitative contribution of titratable acid excretion is less than that of ammonia under basal conditions and is only a minor component of the adaptive response to acid-base disturbances. In contrast to other urinary solutes, ammonia is produced in the kidney and then is selectively transported either into the urine or the renal vein. The proportion of ammonia that the kidney produces that is excreted in the urine varies dramatically in response to physiological stimuli, and only urinary ammonia excretion contributes to acid-base homeostasis. As a result, selective and regulated renal ammonia transport by renal epithelial cells is central to acid-base homeostasis. Both molecular forms of ammonia, NH3 and NH4+, are transported by specific proteins, and regulation of these transport processes determines the eventual fate of the ammonia produced. In this review, we discuss these issues, and then discuss in detail the specific proteins involved in renal epithelial cell ammonia transport.
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Affiliation(s)
- I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida; and Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, Florida
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida; and Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, Florida
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Abstract
PURPOSE OF REVIEW The purpose of this review is to provide a succinct description of the recent findings that advance our understanding of the fundamental renal process of ammonia metabolism and transport in conditions relevant to the clinician. RECENT FINDINGS Recent studies advance our understanding of renal ammonia metabolism. Mechanisms through which chronic kidney disease and altered dietary protein intake alter ammonia excretion have been identified. Lithium, although it can acutely cause distal renal tubular acidosis, was shown with long-term use to increase urinary ammonia excretion, and this appeared to be mediated, at least in part, by increased Rhcg expression. Gene deletion studies showed that the ammonia recycling enzyme, glutamine synthetase, has a critical role in normal-stimulated and acidosis-stimulated ammonia metabolism and that the proximal tubule basolateral bicarbonate transporter, NBCe1, is necessary for normal ammonia metabolism. Finally, our understanding of the molecular ammonia species, NH3 versus NH4, transported by Rh glycoproteins continues to be advanced. SUMMARY Fundamental studies have been recently published that advance our understanding of the regulation of ammonia metabolism in clinically important circumstances, and our understanding of the mechanisms and regulation of proximal tubule ammonia generation, and the mechanisms through which Rh glycoproteins contribute to ammonia secretion.
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Affiliation(s)
- I. David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, FL 32610
- Nephrology and Hypertension Section, North Florida/South Georgia Veterans Health System, Gainesville, FL 32611
| | - Jill W. Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, FL 32610
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Affiliation(s)
- Isabel Rubio-Aliaga
- a Institute of Physiology, the National Center for Competence in Research NCCR Kidney, University of Zurich , Zurich , Switzerland
| | - Carsten A Wagner
- a Institute of Physiology, the National Center for Competence in Research NCCR Kidney, University of Zurich , Zurich , Switzerland
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Shavit L, Chen L, Ahmed F, Ferraro PM, Moochhala S, Walsh SB, Unwin R. Selective screening for distal renal tubular acidosis in recurrent kidney stone formers: initial experience and comparison of the simultaneous furosemide and fludrocortisone test with the short ammonium chloride test. Nephrol Dial Transplant 2016; 31:1870-1876. [PMID: 26961999 DOI: 10.1093/ndt/gfv423] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 11/10/2015] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Distal renal tubular acidosis (dRTA) is associated with renal stone disease, and it often needs to be considered and excluded in some recurrent calcium kidney stone formers (KSFs). However, a diagnosis of dRTA, especially when 'incomplete', can be missed and needs to be confirmed by a urinary acidification (UA) test. The gold standard reference test is still the short ammonium chloride (NH4Cl) test, but it is limited by gastrointestinal side effects and occasionally failure to ingest sufficient NH4Cl. For this reason, the furosemide plus fludrocortisone (F+F) test has been proposed as an easier and better-tolerated screening test. The aim of the present study was to assess the usefulness of the F+F test as a clinical screening tool for dRTA in a renal stone clinic. METHODS We studied 124 patients retrospectively in whom incomplete dRTA was suspected: 71 had kidney stones only, 9 had nephrocalcinosis only and 44 had both. A total of 158 UA tests were performed: 124 F+F and 34 NH4Cl; both tests were completed in 34 patients. RESULTS The mean age was 45.4 ± 15 years, and 49% of patients were male. The prevalence of complete and incomplete dRTAs was 7 and 13.7%, respectively. Of the 34 patients tested using both tests, 17 (50%) were abnormal and 4 (12%) were normal. Thirteen (39%) patients were abnormal by F+F, but normal by NH4Cl [sensitivity 100% (95% CI 80-100), specificity 24% (95% CI 7-50), positive predictive value 57% (95% CI 37-75), negative predictive value 100% (95% CI 40-100)]. CONCLUSIONS The F+F test is characterized by an excellent sensitivity and negative predictive value, and the diagnosis of incomplete dRTA can be excluded reliably in a patient who acidifies their urine normally with this test. However, its lack of specificity is a drawback, and if there is any doubt, an abnormal F+F test may need to be confirmed by a follow-up NH4Cl test. Ideally, a prospective blinded study in unselected KSFs is needed to accurately assess the reliability of the F+F test in diagnosing, rather than excluding, dRTA.
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Affiliation(s)
- Linda Shavit
- UCL Centre for Nephrology, University College London Medical School, Royal Free Campus and Hospital, London, UK
- Adult Nephrology Unit, Shaare Zedek Medical Center, Jerusalem, Israel
| | - Lucia Chen
- UCL Centre for Nephrology, University College London Medical School, Royal Free Campus and Hospital, London, UK
| | - Fayha Ahmed
- Department of Clinical Biochemistry, Royal Free Hospital, London, UK
| | | | - Shabbir Moochhala
- UCL Centre for Nephrology, University College London Medical School, Royal Free Campus and Hospital, London, UK
| | - Steven B Walsh
- UCL Centre for Nephrology, University College London Medical School, Royal Free Campus and Hospital, London, UK
| | - Robert Unwin
- UCL Centre for Nephrology, University College London Medical School, Royal Free Campus and Hospital, London, UK
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Messa PG, Alfieri C, Vettoretti S. Metabolic acidosis in renal transplantation: neglected but of potential clinical relevance. Nephrol Dial Transplant 2015; 31:730-6. [PMID: 25934992 DOI: 10.1093/ndt/gfv098] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 03/10/2015] [Indexed: 11/12/2022] Open
Abstract
Chronic metabolic acidosis (CMA) is a common complication of the more advanced stages of chronic kidney diseases (CKD), and is associated with morbidity and mortality of CKD patients and possibly with the progression of renal disease. Nevertheless, there is limited evidence or information on the prevalence, the potential causal factors, the clinical impact and the effects of correction of CMA in kidney transplant recipients. In this review, we briefly look at the more relevant, though scanty, studies which have, over time, addressed the above-mentioned points, with the hope that in the future the interest of transplant nephrologists and surgeons will grow towards this unreasonably neglected issue.
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Affiliation(s)
- Pier Giorgio Messa
- Unit of Nephrology-Dialysis, Urology and Renal Transplantation, IRCCS Fondazione Ca' Granda-Ospedale Maggiore-Policlinico, Milano, Italy
| | - Carlo Alfieri
- Unit of Nephrology-Dialysis, Urology and Renal Transplantation, IRCCS Fondazione Ca' Granda-Ospedale Maggiore-Policlinico, Milano, Italy
| | - Simone Vettoretti
- Unit of Nephrology-Dialysis, Urology and Renal Transplantation, IRCCS Fondazione Ca' Granda-Ospedale Maggiore-Policlinico, Milano, Italy
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