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Raphael KL. Metabolic Acidosis in CKD: Pathogenesis, Adverse Effects, and Treatment Effects. Int J Mol Sci 2024; 25:5187. [PMID: 38791238 PMCID: PMC11121226 DOI: 10.3390/ijms25105187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 04/28/2024] [Accepted: 05/05/2024] [Indexed: 05/26/2024] Open
Abstract
Metabolic acidosis is a frequent complication of chronic kidney disease and is associated with a number of adverse outcomes, including worsening kidney function, poor musculoskeletal health, cardiovascular events, and death. Mechanisms that prevent metabolic acidosis detrimentally promote further kidney damage, creating a cycle between acid accumulation and acid-mediated kidney injury. Disrupting this cycle through the provision of alkali, most commonly using sodium bicarbonate, is hypothesized to preserve kidney function while also mitigating adverse effects of excess acid on bone and muscle. However, results from clinical trials have been conflicting. There is also significant interest to determine whether sodium bicarbonate might improve patient outcomes for those who do not have overt metabolic acidosis. Such individuals are hypothesized to be experiencing acid-mediated organ damage despite having a normal serum bicarbonate concentration, a state often referred to as subclinical metabolic acidosis. Results from small- to medium-sized trials in individuals with subclinical metabolic acidosis have also been inconclusive. Well-powered clinical trials to determine the efficacy and safety of sodium bicarbonate are necessary to determine if this intervention improves patient outcomes.
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Affiliation(s)
- Kalani L. Raphael
- Division of Nephrology & Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT 84112, USA;
- Medicine Section, Veterans Affairs Salt Lake City Health Care System, Salt Lake City, UT 84148, USA
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Daryadel A, Küng CJ, Haykir B, Sabrautzki S, de Angelis MH, Hernando N, Rubio-Aliaga I, Wagner CA. The calcium-sensing receptor has only a parathyroid hormone-dependent role in the acute response of renal phosphate transporters to phosphate intake. Am J Physiol Renal Physiol 2024; 326:F792-F801. [PMID: 38545651 DOI: 10.1152/ajprenal.00009.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/22/2024] [Accepted: 03/22/2024] [Indexed: 05/04/2024] Open
Abstract
The kidney controls systemic inorganic phosphate (Pi) levels by adapting reabsorption to Pi intake. Renal Pi reabsorption is mostly mediated by sodium-phosphate cotransporters NaPi-IIa (SLC34A1) and NaPi-IIc (SLC34A3) that are tightly controlled by various hormones including parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23). PTH and FGF23 rise in response to Pi intake and decrease NaPi-IIa and NaPi-IIc brush border membrane abundance enhancing phosphaturia. Phosphaturia and transporter regulation occurs even in the absence of PTH and FGF23 signaling. The calcium-sensing receptor (CaSR) regulates PTH and FGF23 secretion, and may also directly affect renal Pi handling. Here, we combined pharmacological and genetic approaches to examine the role of the CaSR in the acute phosphaturic response to Pi loading. Animals pretreated with the calcimimetic cinacalcet were hyperphosphatemic, had blunted PTH levels upon Pi administration, a reduced Pi-induced phosphaturia, and no Pi-induced NaPi-IIa downregulation. The calcilytic NPS-2143 exaggerated the PTH response to Pi loading but did not abolish Pi-induced downregulation of NaPi-IIa. In mice with a dominant inactivating mutation in the Casr (CasrBCH002), baseline NaPi-IIa expression was higher, whereas downregulation of transporter expression was blunted in double CasrBCH002/PTH knockout (KO) transgenic animals. Thus, in response to an acute Pi load, acute modulation of the CaSR affects the endocrine and renal response, whereas chronic genetic inactivation, displays only subtle differences in the downregulation of NaPi-IIa and NaPi-IIc renal expression. We did not find evidence that the CaSR impacts on the acute renal response to oral Pi loading beyond its role in regulating PTH secretion.NEW & NOTEWORTHY Consumption of phosphate-rich diets causes an adaptive response of the body leading to the urinary excretion of phosphate. The underlying mechanisms are still poorly understood. Here, we examined the role of the calcium-sensing receptor (CaSR) that senses both calcium and phosphate. We confirmed that the receptor increases the secretion of parathyroid hormone involved in stimulating urinary phosphate excretion. However, we did not find any evidence for a role of the receptor beyond this function.
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Affiliation(s)
- Arezoo Daryadel
- Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Catharina J Küng
- Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Betül Haykir
- Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Sibylle Sabrautzki
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Martin Hrabĕ de Angelis
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Lehrstuhl für Experimentelle Genetik, Technische Universität München, Freising, Germany
- Member of German Center for Diabetes Research, Neuherberg, Germany
| | - Nati Hernando
- Institute of Physiology, University of Zürich, Zürich, Switzerland
| | | | - Carsten A Wagner
- Institute of Physiology, University of Zürich, Zürich, Switzerland
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Raphael KL, Katz R, Larive B, Kendrick C, Isakova T, Sprague S, Wolf M, Raj DS, Fried LF, Gassman J, Hoofnagle A, Cheung AK, Ix JH. Oral Sodium Bicarbonate and Bone Turnover in CKD: A Secondary Analysis of the BASE Pilot Trial. J Am Soc Nephrol 2024; 35:57-65. [PMID: 38170601 PMCID: PMC10786609 DOI: 10.1681/asn.0000000000000264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 10/18/2023] [Indexed: 01/05/2024] Open
Abstract
SIGNIFICANCE STATEMENT In CKD, metabolic acidosis is commonly treated with alkali in the hope that it will improve bone health. In a post hoc analysis of the Bicarbonate Administration to Stabilize eGFR Pilot Trial, we investigated whether sodium bicarbonate affects serum levels of bone turnover markers and other hormones related to bone health in individuals with CKD who have normal to slightly reduced total CO2 (20-28 mEq/L). Sodium bicarbonate increased serum levels of α-klotho but had no significant effect on other bone health markers, including intact fibroblast growth factor-23 (iFGF-23), intact parathyroid hormone (iPTH), and bone-specific alkaline phosphatase (B-SAP). Further study is needed to determine the effect of bicarbonate administration on clinical aspects of bone health. BACKGROUND Treatment with alkali has been hypothesized to improve bone health in CKD by mitigating adverse effects of acid on bone mineral. We investigated the effect of treatment with sodium bicarbonate on bone turnover markers and other factors related to bone metabolism in CKD. METHODS This is a post hoc analysis of the Bicarbonate Administration to Stabilize eGFR Pilot Trial in which 194 individuals with CKD and serum total CO2 20-28 mEq/L were randomly assigned to placebo or one of two doses of sodium bicarbonate (0.5 or 0.8 mEq/kg lean body weight per day) for 28 weeks. The following serum measurements were performed at baseline, week 12, and week 28: B-SAP, c-telopeptide, procollagen type I intact N-terminal propeptide, iPTH, iFGF-23, soluble klotho, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and tartrate-resistant acid phosphatase 5b. The difference (sodium bicarbonate versus placebo) in mean change of each bone biomarker from baseline was determined using linear mixed models. RESULTS One hundred sixty-eight participants submitted samples for post hoc investigations. Mean eGFR was 37±10 ml/min per 1.73 m2 and mean total CO2 was 24±3 mEq/L at baseline. Sodium bicarbonate induced a dose-dependent increase in soluble klotho levels compared with placebo. There was no significant effect of treatment with either dose of sodium bicarbonate on any of the other bone biomarkers, including iFGF-23, iPTH, and B-SAP. Effects on bone biomarkers were similar in those with baseline serum total CO2 <24 mEq/L compared with those with total CO2 ≥24 mEq/L. CONCLUSIONS In this pilot trial of individuals with CKD and total CO2 20-28 mEq/L, sodium bicarbonate treatment increased serum klotho levels but did not affect other bone health markers over 28 weeks. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER ClinicalTrials.gov, NCT02521181.
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Affiliation(s)
- Kalani L. Raphael
- University of Utah Health and VA Salt Lake City Health Care System, Salt Lake City, Utah
| | - Ronit Katz
- Department of Obstetrics & Gynecology, University of Washington, Seattle, Washington
| | | | | | - Tamara Isakova
- Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Stuart Sprague
- Division of Nephrology & Hypertension, Northshore University Health System-University of Chicago, Evanston, Illinois
| | - Myles Wolf
- Division of Nephrology, Department of Medicine, Duke Clinical Research Institute, Duke University School of Medicine, Durham, North Carolina
| | - Dominic S. Raj
- George Washington University School of Medicine, Washington, DC
| | - Linda F. Fried
- University of Pittsburgh and VA Pittsburgh Health Care System, Pittsburgh, Pennsylvania
| | | | - Andy Hoofnagle
- Department of Obstetrics & Gynecology, University of Washington, Seattle, Washington
| | - Alfred K. Cheung
- University of Utah Health and VA Salt Lake City Health Care System, Salt Lake City, Utah
| | - Joachim H. Ix
- University of California San Diego and VA San Diego Health Care System, San Diego, California
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Edmonston D, Grabner A, Wolf M. FGF23 and klotho at the intersection of kidney and cardiovascular disease. Nat Rev Cardiol 2024; 21:11-24. [PMID: 37443358 DOI: 10.1038/s41569-023-00903-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/13/2023] [Indexed: 07/15/2023]
Abstract
Cardiovascular disease is the leading cause of death in patients with chronic kidney disease (CKD). As CKD progresses, CKD-specific risk factors, such as disordered mineral homeostasis, amplify traditional cardiovascular risk factors. Fibroblast growth factor 23 (FGF23) regulates mineral homeostasis by activating complexes of FGF receptors and transmembrane klotho co-receptors. A soluble form of klotho also acts as a 'portable' FGF23 co-receptor in tissues that do not express klotho. In progressive CKD, rising circulating FGF23 levels in combination with decreasing kidney expression of klotho results in klotho-independent effects of FGF23 on the heart that promote left ventricular hypertrophy, heart failure, atrial fibrillation and death. Emerging data suggest that soluble klotho might mitigate some of these effects via several candidate mechanisms. More research is needed to investigate FGF23 excess and klotho deficiency in specific cardiovascular complications of CKD, but the pathophysiological primacy of FGF23 excess versus klotho deficiency might never be precisely resolved, given the entangled feedback loops that they share. Therefore, randomized trials should prioritize clinical practicality over scientific certainty by targeting disordered mineral homeostasis holistically in an effort to improve cardiovascular outcomes in patients with CKD.
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Affiliation(s)
- Daniel Edmonston
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
- Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, USA
| | - Alexander Grabner
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, USA
| | - Myles Wolf
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, USA.
- Duke Clinical Research Institute, Duke University School of Medicine, Durham, NC, USA.
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Li SS, Sheng MJ, Sun ZY, Liang Y, Yu LX, Liu QF. Upstream and downstream regulators of Klotho expression in chronic kidney disease. Metabolism 2023; 142:155530. [PMID: 36868370 DOI: 10.1016/j.metabol.2023.155530] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 02/22/2023] [Accepted: 02/23/2023] [Indexed: 03/05/2023]
Abstract
Klotho is a critical protein that protects the kidney. Klotho is severely downregulated in chronic kidney disease (CKD), and its deficiency is implicated in the pathogenesis and progression of CKD. Conversely, an increase in Klotho levels results in improved kidney function and delays CKD progression, supporting the notion that modulating Klotho levels could represent a possible therapeutic strategy for CKD treatment. Nevertheless, the regulatory mechanisms responsible for the loss of Klotho remain elusive. Previous studies have demonstrated that oxidative stress, inflammation, and epigenetic modifications can modulate Klotho levels. These mechanisms result in a decrease in Klotho mRNA transcript levels and reduced translation, thus can be grouped together as upstream regulatory mechanisms. However, therapeutic strategies that aim to rescue Klotho levels by targeting these upstream mechanisms do not always result in increased Klotho, indicating the involvement of other regulatory mechanisms. Emerging evidence has shown that endoplasmic reticulum (ER) stress, the unfolded protein response, and ER-associated degradation also affect the modification, translocation, and degradation of Klotho, and thus are proposed to be downstream regulatory mechanisms. Here, we discuss the current understanding of upstream and downstream regulatory mechanisms of Klotho and examine potential therapeutic strategies to upregulate Klotho expression for CKD treatment.
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Affiliation(s)
- Sha-Sha Li
- Clinical Research & Lab Centre, Affiliated Kunshan Hospital of Jiangsu University, 91 Qianjin West Road, Kunshan, Jiangsu 215300, China
| | - Ming-Jie Sheng
- Department of Nephrology, Affiliated Kunshan Hospital of Jiangsu University, 91 Qianjin West Road, Kunshan, Jiangsu 215300, China
| | - Zhuo-Yi Sun
- Department of Nephrology, Affiliated Kunshan Hospital of Jiangsu University, 91 Qianjin West Road, Kunshan, Jiangsu 215300, China
| | - Yan Liang
- Gusu School, Nanjing Medical University, The First People's Hospital of Kunshan, 91 Qianjin West Road, Kunshan, Jiangsu 215300, China
| | - Li-Xia Yu
- Department of Nephrology, Affiliated Kunshan Hospital of Jiangsu University, 91 Qianjin West Road, Kunshan, Jiangsu 215300, China.
| | - Qi-Feng Liu
- Department of Nephrology, Affiliated Kunshan Hospital of Jiangsu University, 91 Qianjin West Road, Kunshan, Jiangsu 215300, China; Gusu School, Nanjing Medical University, The First People's Hospital of Kunshan, 91 Qianjin West Road, Kunshan, Jiangsu 215300, China.
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Noonin C, Itsaranawet T, Thongboonkerd V. Calcium oxalate crystal-induced secretome derived from proximal tubular cells, not that from distal tubular cells, induces renal fibroblast activation. Eur J Med Res 2023; 28:150. [PMID: 37031165 PMCID: PMC10082508 DOI: 10.1186/s40001-023-01109-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Accepted: 03/24/2023] [Indexed: 04/10/2023] Open
Abstract
BACKGROUND Kidney stone disease (KSD) is commonly accompanied with renal fibrosis, characterized by accumulation and reorganization of extracellular matrix (ECM). During fibrogenesis, resident renal fibroblasts are activated to become myofibroblasts that actively produce ECM. However, such fibroblast-myofibroblast differentiation in KSD remained unclear. Our present study thus examined effects of secreted products (secretome) derived from proximal (HK-2) vs. distal (MDCK) renal tubular cells exposed to calcium oxalate monohydrate (COM) crystals on activation of renal fibroblasts (BHK-21). METHODS HK-2 and MDCK cells were treated with 100 µg/ml COM crystals under serum-free condition for 16 h. In parallel, the cells maintained in serum-free medium without COM treatment served as the control. Secretome derived from culture supernatant of each sample was mixed (1:1) with fresh serum-free medium and then used for BHK-21 culture for another 24 h. RESULTS Analyses revealed that COM-treated-HK-2 secretome significantly induced proliferation, caused morphological changes, increased spindle index, and upregulated fibroblast-activation markers (F-actin, α-SMA and fibronectin) in BHK-21 cells. However, COM-treated-MDCK secretome had no significant effects on these BHK-21 parameters. Moreover, level of transforming growth factor-β1 (TGF-β1), a profibrotic factor, significantly increased in the COM-treated-HK-2 secretome but not in the COM-treated-MDCK secretome. CONCLUSIONS These data indicate, for the first time, that proximal and distal tubular epithelial cells exposed to COM crystals send different messages to resident renal fibroblasts. Only the secretome derived from proximal tubular cells, not that from the distal cells, induces renal fibroblast activation after their exposure to COM crystals. Such differential effects are partly due to TGF-β1 secretion, which is induced by COM crystals only in proximal tubular cells.
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Affiliation(s)
- Chadanat Noonin
- Medical Proteomics Unit, Research Department, Faculty of Medicine Siriraj Hospital, Mahidol University, 6th Floor - SiMR Building, 2 Wanglang Road, Bangkoknoi, 10700, Bangkok, Thailand
| | - Tanakorn Itsaranawet
- Biological Sciences Program, Mahidol University International College, Nakhon Pathom, 73170, Thailand
| | - Visith Thongboonkerd
- Medical Proteomics Unit, Research Department, Faculty of Medicine Siriraj Hospital, Mahidol University, 6th Floor - SiMR Building, 2 Wanglang Road, Bangkoknoi, 10700, Bangkok, Thailand.
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The mechanisms of alkali therapy in targeting renal diseases. Biochem Soc Trans 2023; 51:223-232. [PMID: 36744634 DOI: 10.1042/bst20220690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/28/2022] [Accepted: 01/19/2023] [Indexed: 02/07/2023]
Abstract
Chronic kidney disease (CKD) is characterized by progressive reduction in kidney function and treatments aiming at stabilizing or slowing its progression may avoid or delay the necessity of kidney replacement therapy and the increased mortality associated with reduced kidney function. Metabolic acidosis, and less severe stages of the acid stress continuum, are common consequences of CKD and some interventional studies support that its correction slows the progression to end-stage kidney disease. This correction can be achieved with mineral alkali in the form of bicarbonate or citrate salts, ingestion of diets with fewer acid-producing food components or more base-producing food components, or a pharmacological approach. In this mini-review article, we summarize the potential mechanisms involved in the beneficial effects of alkali therapy. We also discuss the perspectives in the field and challenges that must be overcome to advance our understanding of such mechanisms.
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Bahena-Lopez JP, Rojas-Vega L, Chávez-Canales M, Bazua-Valenti S, Bautista-Pérez R, Lee JH, Madero M, Vazquez-Manjarrez N, Alquisiras-Burgos I, Hernandez-Cruz A, Castañeda-Bueno M, Ellison DH, Gamba G. Glucose/Fructose Delivery to the Distal Nephron Activates the Sodium-Chloride Cotransporter via the Calcium-Sensing Receptor. J Am Soc Nephrol 2023; 34:55-72. [PMID: 36288902 PMCID: PMC10101570 DOI: 10.1681/asn.2021121544] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 08/07/2022] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND The calcium-sensing receptor (CaSR) in the distal convoluted tubule (DCT) activates the NaCl cotransporter (NCC). Glucose acts as a positive allosteric modulator of the CaSR. Under physiologic conditions, no glucose is delivered to the DCT, and fructose delivery depends on consumption. We hypothesized that glucose/fructose delivery to the DCT modulates the CaSR in a positive allosteric way, activating the WNK4-SPAK-NCC pathway and thus increasing salt retention. METHODS We evaluated the effect of glucose/fructose arrival to the distal nephron on the CaSR-WNK4-SPAK-NCC pathway using HEK-293 cells, C57BL/6 and WNK4-knockout mice, ex vivo perfused kidneys, and healthy humans. RESULTS HEK-293 cells exposed to glucose/fructose increased SPAK phosphorylation in a WNK4- and CaSR-dependent manner. C57BL/6 mice exposed to fructose or a single dose of dapagliflozin to induce transient glycosuria showed increased activity of the WNK4-SPAK-NCC pathway. The calcilytic NPS2143 ameliorated this effect, which was not observed in WNK4-KO mice. C57BL/6 mice treated with fructose or dapagliflozin showed markedly increased natriuresis after thiazide challenge. Ex vivo rat kidney perfused with glucose above the physiologic threshold levels for proximal reabsorption showed increased NCC and SPAK phosphorylation. NPS2143 prevented this effect. In healthy volunteers, cinacalcet administration, fructose intake, or a single dose of dapagliflozin increased SPAK and NCC phosphorylation in urinary extracellular vesicles. CONCLUSIONS Glycosuria or fructosuria was associated with increased NCC, SPAK, and WNK4 phosphorylation in a CaSR-dependent manner.
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Affiliation(s)
- Jessica Paola Bahena-Lopez
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
- MD/PhD (PECEM) program, Faculty of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Lorena Rojas-Vega
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
- Intellectual Property Unit, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - María Chávez-Canales
- Unidad de Investigación UNAM-INCICH, Instituto Nacional de Cardiología Ignacio Chávez and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Silvana Bazua-Valenti
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Rocío Bautista-Pérez
- Department of Molecular Biology, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico
| | - Ju-Hye Lee
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Magdalena Madero
- Department of Nephrology, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico
| | - Natalia Vazquez-Manjarrez
- Nutrition Division, Department of Nutrition Physiology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Ivan Alquisiras-Burgos
- Department of Cognitive Neuroscience, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Arturo Hernandez-Cruz
- Department of Cognitive Neuroscience, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - María Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - David H. Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
- Oregon Clinical and Translational Research Institute, Oregon Health and Science University, Portland, Oregon
- VA Portland Health Care System, Portland, Oregon
| | - Gerardo Gamba
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
- MD/PhD (PECEM) program, Faculty of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Hu SM, Bai YJ, Li YM, Tao Y, Wang XD, Lin T, Wang LL, Shi YY. Cholecalciferol supplementation effectively improved tertiary hyperparathyroidism, FGF23 resistance and lowered coronary calcification score: a prospective study. Endocr Connect 2022; 11:EC-22-0123. [PMID: 35904219 PMCID: PMC9346334 DOI: 10.1530/ec-22-0123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 06/30/2022] [Indexed: 02/05/2023]
Abstract
INTRODUCTION Tertiary hyperparathyroidism (THPT) and vitamin D deficiency are commonly seen in kidney transplant recipients, which may result in persistently elevated fibroblast growth factor 23 (FGF23) level after transplantation and decreased graft survival. The aim of this study is to evaluate the effect of vitamin D supplementation on THPT, FGF23-alpha Klotho (KLA) axis and cardiovascular complications after transplantation. MATERIALS AND METHODS Two hundred nine kidney transplant recipients were included and further divided into treated and untreated groups depending on whether they received vitamin D supplementation. We tracked the state of THPT, bone metabolism and FGF23-KLA axis within 12 months posttransplant and explored the predictors and risk factors for intact FGF23 levels, KLA levels, THPT and cardiovascular complications in recipients. RESULTS Vitamin D supplementation significantly improved FGF23 resistance, THPT and high bone turnover status, preserved better graft function and prevented coronary calcification in the treated group compared to the untreated group at month 12. The absence of vitamin D supplementation was an independent risk factor for THPT and a predictor for intact FGF23 and KLA levels at month 12. Age and vitamin D deficiency were independent risk factors for coronary calcification in recipients at month 12. CONCLUSION Vitamin D supplementation effectively improved THPT, FGF23 resistance and bone metabolism, preserved graft function and prevented coronary calcification after transplantation.
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Affiliation(s)
- Shu-Meng Hu
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yang-Juan Bai
- Department of Laboratory Medicine/Research Centre of Clinical Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Ya-Mei Li
- Department of Laboratory Medicine/Research Centre of Clinical Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Ye Tao
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Xian-Ding Wang
- Department of Urology/Institute of Urology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Tao Lin
- Department of Urology/Institute of Urology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Lan-Lan Wang
- Department of Laboratory Medicine/Research Centre of Clinical Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Yun-Ying Shi
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
- Correspondence should be addressed to Y-Y Shi:
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10
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The importance of kidney calcium handling in the homeostasis of extracellular fluid calcium. Pflugers Arch 2022; 474:885-900. [PMID: 35842482 DOI: 10.1007/s00424-022-02725-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/09/2022] [Accepted: 06/30/2022] [Indexed: 12/13/2022]
Abstract
Extracellular fluid calcium concentration must be maintained within a narrow range in order to sustain many biological functions, encompassing muscle contraction, blood coagulation, and bone and tooth mineralization. Blood calcium value is critically dependent on the ability of the renal tubule to reabsorb the adequate amount of filtered calcium. Tubular calcium reabsorption is carried out by various and complex mechanisms in 3 distinct segments: the proximal tubule, the cortical thick ascending limb of the loop of Henle, and the late distal convoluted/connecting tubule. In addition, calcium reabsorption is tightly controlled by many endocrine, paracrine, and autocrine factors, as well as by non-hormonal factors, in order to adapt the tubular handling of calcium to the metabolic requirements. The present review summarizes the current knowledge of the mechanisms and factors involved in calcium handling by the kidney and, ultimately, in extracellular calcium homeostasis. The review also highlights some of our gaps in understanding that need to be addressed in the future.
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Schepelmann M, Ranieri M, Lopez-Fernandez I, Webberley TS, Brennan SC, Yarova PL, Graca J, Hanif UK, Müller C, Manhardt T, Salzmann M, Quasnichka H, Price SA, Ward DT, Gilbert T, Matchkov VV, Fenton RA, Herberger A, Hwong J, Santa Maria C, Tu CL, Kallay E, Valenti G, Chang W, Riccardi D. Impaired Mineral Ion Metabolism in a Mouse Model of Targeted Calcium-Sensing Receptor (CaSR) Deletion from Vascular Smooth Muscle Cells. J Am Soc Nephrol 2022; 33:1323-1340. [PMID: 35581010 PMCID: PMC9257819 DOI: 10.1681/asn.2021040585] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 03/07/2022] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Impaired mineral ion metabolism is a hallmark of CKD-metabolic bone disorder. It can lead to pathologic vascular calcification and is associated with an increased risk of cardiovascular mortality. Loss of calcium-sensing receptor (CaSR) expression in vascular smooth muscle cells exacerbates vascular calcification in vitro. Conversely, vascular calcification can be reduced by calcimimetics, which function as allosteric activators of CaSR. METHODS To determine the role of the CaSR in vascular calcification, we characterized mice with targeted Casr gene knockout in vascular smooth muscle cells ( SM22α CaSR Δflox/Δflox ). RESULTS Vascular smooth muscle cells cultured from the knockout (KO) mice calcified more readily than those from control (wild-type) mice in vitro. However, mice did not show ectopic calcifications in vivo but they did display a profound mineral ion imbalance. Specifically, KO mice exhibited hypercalcemia, hypercalciuria, hyperphosphaturia, and osteopenia, with elevated circulating fibroblast growth factor 23 (FGF23), calcitriol (1,25-D3), and parathyroid hormone levels. Renal tubular α-Klotho protein expression was increased in KO mice but vascular α-Klotho protein expression was not. Altered CaSR expression in the kidney or the parathyroid glands could not account for the observed phenotype of the KO mice. CONCLUSIONS These results suggest that, in addition to CaSR's established role in the parathyroid-kidney-bone axis, expression of CaSR in vascular smooth muscle cells directly contributes to total body mineral ion homeostasis.
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Affiliation(s)
- Martin Schepelmann
- School of Biosciences, Cardiff University, Cardiff, United Kingdom .,Institute of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
| | - Marianna Ranieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | | | | | - Sarah C Brennan
- School of Biosciences, Cardiff University, Cardiff, United Kingdom.,Charles Perkins Centre, University of Sydney, Sydney, Australia
| | - Polina L Yarova
- School of Biosciences, Cardiff University, Cardiff, United Kingdom.,Translational and Clinical Research Institute, Newcastle University Medical School, Newcastle upon Tyne, United Kingdom
| | - Joao Graca
- School of Biosciences, Cardiff University, Cardiff, United Kingdom.,AstraZeneca, Macclesfield, United Kingdom
| | | | - Christian Müller
- Institute of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
| | - Teresa Manhardt
- Institute of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
| | - Martina Salzmann
- Institute of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
| | - Helen Quasnichka
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | | | - Donald T Ward
- Division of Diabetes, Endocrinology, and Gastroenterology, University of Manchester, Manchester, United Kingdom
| | - Thierry Gilbert
- Centre for Developmental Biology, University Paul Sabatier, Toulouse, France
| | | | - Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Amanda Herberger
- Department of Medicine, University of California, San Francisco, California
| | - Jenna Hwong
- Department of Medicine, University of California, San Francisco, California
| | | | - Chia-Ling Tu
- Department of Medicine, University of California, San Francisco, California
| | - Enikö Kallay
- Institute of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
| | - Giovanna Valenti
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Wenhan Chang
- Department of Medicine, University of California, San Francisco, California
| | - Daniela Riccardi
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
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Imenez Silva PH, Mohebbi N. Kidney metabolism and acid-base control: back to the basics. Pflugers Arch 2022; 474:919-934. [PMID: 35513635 PMCID: PMC9338915 DOI: 10.1007/s00424-022-02696-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 01/18/2023]
Abstract
Kidneys are central in the regulation of multiple physiological functions, such as removal of metabolic wastes and toxins, maintenance of electrolyte and fluid balance, and control of pH homeostasis. In addition, kidneys participate in systemic gluconeogenesis and in the production or activation of hormones. Acid-base conditions influence all these functions concomitantly. Healthy kidneys properly coordinate a series of physiological responses in the face of acute and chronic acid-base disorders. However, injured kidneys have a reduced capacity to adapt to such challenges. Chronic kidney disease patients are an example of individuals typically exposed to chronic and progressive metabolic acidosis. Their organisms undergo a series of alterations that brake large detrimental changes in the homeostasis of several parameters, but these alterations may also operate as further drivers of kidney damage. Acid-base disorders lead not only to changes in mechanisms involved in acid-base balance maintenance, but they also affect multiple other mechanisms tightly wired to it. In this review article, we explore the basic renal activities involved in the maintenance of acid-base balance and show how they are interconnected to cell energy metabolism and other important intracellular activities. These intertwined relationships have been investigated for more than a century, but a modern conceptual organization of these events is lacking. We propose that pH homeostasis indissociably interacts with central pathways that drive progression of chronic kidney disease, such as inflammation and metabolism, independent of etiology.
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Affiliation(s)
- Pedro Henrique Imenez Silva
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
- National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.
| | - Nilufar Mohebbi
- National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
- Praxis Und Dialysezentrum Zurich, Zurich, Switzerland
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