51
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Shin S, Boadi EA, Bandyopadhyay BC. Ablation of TRPC3 compromises bicarbonate and phosphate transporter activity in mice proximal tubular cells. Clin Exp Pharmacol Physiol 2023; 50:247-255. [PMID: 36433745 PMCID: PMC10258833 DOI: 10.1111/1440-1681.13741] [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: 05/11/2022] [Revised: 11/19/2022] [Accepted: 11/21/2022] [Indexed: 11/28/2022]
Abstract
Proximal tubular (PT) cells reabsorb most calcium (Ca2+ ), phosphate (PO4 3- ), bicarbonate (HCO3 - ), and oxalate (C2 O4 2- ) ions. We have shown that mice lacking Transient Receptor Potential Canonical 3 (TRPC3-/- ) channel are moderately hypercalciuric with presentation of luminal calcium phosphate (CaP) crystals at the loop of Henle (LOH). However, other predisposing factors for such crystal deposition are unknown. Thus, we examined the distinctions in functional status of HCO3 - , PO4 3- , and C2 O4 2- transporters in PT cells of wild type (WT) and TRPC3-/- mice by whole-cell patch clamp techniques to assess their contribution in the development of LOH CaP crystals. Here we show the development of concentration dependent HCO3 - -induced currents in all PT cells, which was confirmed by using specific HCO3 - channel inhibitor, S0859. Interestingly, such activities were diminished in PT cells from TRPC3-/- mice, suggesting reduced HCO3 - transport in absence of TRPC3. While PO4 3- -induced currents were also concentration dependent in all PT cells (confirmed by PO4 3- channel inhibitor, PF-06869206), those activities were reduced in absence of TRPC3, suggesting lower PO4 3- reabsorption that can leave excess luminal PO4 3- . Next, we applied thiosulfate (O3 S2 2 - ) as a competitive inhibitor of the SLC26a6 transporter upon C2 O4 2- current activation and observed a reduced C2 O4 2- -induced conductance which was greater in TRPC3-/- PT cells. Together, these results suggest that the reduced activities of HCO3 - , PO4 3- , and C2 O4 2- transporters in moderately hypercalciuric (TRPC3-/- ) PT cells can create a predisposing condition for CaP and CaP tubular crystallization, enabling CaP crystal formation in LOH of TRPC3-/- mice.
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Affiliation(s)
- Samuel Shin
- Calcium Signaling Laboratory, Research Service, Veterans Affairs Medical Center, Washington, Columbia, USA
| | - Eugenia Awuah Boadi
- Calcium Signaling Laboratory, Research Service, Veterans Affairs Medical Center, Washington, Columbia, USA
| | - Bidhan C. Bandyopadhyay
- Calcium Signaling Laboratory, Research Service, Veterans Affairs Medical Center, Washington, Columbia, USA
- Division of Renal Diseases & Hypertension, Department of Medicine, The George Washington University, Washington, Columbia, USA
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52
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Drummond BE, Ercanbrack WS, Wingert RA. Modeling Podocyte Ontogeny and Podocytopathies with the Zebrafish. J Dev Biol 2023; 11:jdb11010009. [PMID: 36810461 PMCID: PMC9944608 DOI: 10.3390/jdb11010009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/11/2023] [Accepted: 02/17/2023] [Indexed: 02/22/2023] Open
Abstract
Podocytes are exquisitely fashioned kidney cells that serve an essential role in the process of blood filtration. Congenital malformation or damage to podocytes has dire consequences and initiates a cascade of pathological changes leading to renal disease states known as podocytopathies. In addition, animal models have been integral to discovering the molecular pathways that direct the development of podocytes. In this review, we explore how researchers have used the zebrafish to illuminate new insights about the processes of podocyte ontogeny, model podocytopathies, and create opportunities to discover future therapies.
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53
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Estrogen Signaling Influences Nephron Segmentation of the Zebrafish Embryonic Kidney. Cells 2023; 12:cells12040666. [PMID: 36831333 PMCID: PMC9955091 DOI: 10.3390/cells12040666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 02/13/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023] Open
Abstract
Despite significant advances in understanding nephron segment patterning, many questions remain about the underlying genes and signaling pathways that orchestrate renal progenitor cell fate choices and regulate differentiation. In an effort to identify elusive regulators of nephron segmentation, our lab conducted a high-throughput drug screen using a bioactive chemical library and developing zebrafish, which are a conserved vertebrate model and particularly conducive to large-scale screening approaches. 17β-estradiol (E2), which is the dominant form of estrogen in vertebrates, was a particularly interesting hit from this screen. E2 has been extensively studied in the context of gonad development, but roles for E2 in nephron development were unknown. Here, we report that exogenous estrogen treatments affect distal tubule composition, namely, causing an increase in the distal early segment and a decrease in the neighboring distal late. These changes were noted early in development but were not due to changes in cell dynamics. Interestingly, exposure to the xenoestrogens ethinylestradiol and genistein yielded the same changes in distal segments. Further, upon treatment with an estrogen receptor 2 (Esr2) antagonist, PHTPP, we observed the opposite phenotypes. Similarly, genetic deficiency of the Esr2 analog, esr2b, revealed phenotypes consistent with that of PHTPP treatment. Inhibition of E2 signaling also resulted in decreased expression of essential distal transcription factors, irx3b and its target irx1a. These data suggest that estrogenic compounds are essential for distal segment fate during nephrogenesis in the zebrafish pronephros and expand our fundamental understanding of hormone function during kidney organogenesis.
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54
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The "3Ds" of Growing Kidney Organoids: Advances in Nephron Development, Disease Modeling, and Drug Screening. Cells 2023; 12:cells12040549. [PMID: 36831216 PMCID: PMC9954122 DOI: 10.3390/cells12040549] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/03/2023] [Accepted: 02/07/2023] [Indexed: 02/11/2023] Open
Abstract
A kidney organoid is a three-dimensional (3D) cellular aggregate grown from stem cells in vitro that undergoes self-organization, recapitulating aspects of normal renal development to produce nephron structures that resemble the native kidney organ. These miniature kidney-like structures can also be derived from primary patient cells and thus provide simplified context to observe how mutations in kidney-disease-associated genes affect organogenesis and physiological function. In the past several years, advances in kidney organoid technologies have achieved the formation of renal organoids with enhanced numbers of specialized cell types, less heterogeneity, and more architectural complexity. Microfluidic bioreactor culture devices, single-cell transcriptomics, and bioinformatic analyses have accelerated the development of more sophisticated renal organoids and tailored them to become increasingly amenable to high-throughput experimentation. However, many significant challenges remain in realizing the use of kidney organoids for renal replacement therapies. This review presents an overview of the renal organoid field and selected highlights of recent cutting-edge kidney organoid research with a focus on embryonic development, modeling renal disease, and personalized drug screening.
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55
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Radovic S, Meng W, Chen L, Mondolfi AEP, Bryce C, Grimes Z, Sordillo EM, Cordon-Cardo C, Guo H, Huang Y, Gao SJ. SARS-CoV-2 infection of kidney tissues from severe COVID-19 patients. J Med Virol 2023; 95:e28566. [PMID: 36756942 PMCID: PMC10388714 DOI: 10.1002/jmv.28566] [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: 01/13/2023] [Revised: 02/01/2023] [Accepted: 02/06/2023] [Indexed: 02/10/2023]
Abstract
BACKGROUND Coronavirus disease 2019 (COVID-19) caused by infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) manifests diverse clinical pathologies involving multiple organs. While the respiratory tract is the primary SARS-CoV-2 target, acute kidney injury is common in COVID-19 patients, displaying as acute tubular necrosis (ATN) resulting from focal epithelial necrosis and eosinophilia, glomerulosclerosis, and autolysis of renal tubular cells. However, whether any renal cells are infected by SARS-CoV-2 and the mechanism involved in the COVID-19 kidney pathology remain unclear. METHODS Kidney tissues obtained at autopsy from four severe COVID-19 patients and one healthy subject were examined by hematoxylin and eosin staining. Indirect immunofluorescent antibody assay was performed to detect SARS-CoV-2 spike protein S1 and nonstructural protein 8 (NSP8) together with markers of different kidney cell types and immune cells to identify the infected cells. RESULTS Renal parenchyma showed tissue injury comprised of ATN and glomerulosclerosis. Positive staining of S1 protein was observed in renal parenchymal and tubular epithelial cells. Evidence of viral infection was also observed in innate monocytes/macrophages and NK cells. Positive staining of NSP8, which is essential for viral RNA synthesis and replication, was confirmed in renal parenchymal cells, indicating the presence of active viral replication in the kidney. CONCLUSIONS In fatal COVID-19 kidneys, there are SARS-CoV-2 infection, minimally infiltrated innate immune cells, and evidence of viral replication, which could contribute to tissue damage in the form of ATN and glomerulosclerosis.
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Affiliation(s)
- Shawn Radovic
- Cancer Virology Program, UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Wen Meng
- Cancer Virology Program, UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Luping Chen
- Cancer Virology Program, UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Alberto E. Paniz Mondolfi
- Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mt. Sinai, New York, New York, USA
| | - Clare Bryce
- Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mt. Sinai, New York, New York, USA
| | - Zachary Grimes
- Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mt. Sinai, New York, New York, USA
| | - Emilia M. Sordillo
- Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mt. Sinai, New York, New York, USA
| | - Carlos Cordon-Cardo
- Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mt. Sinai, New York, New York, USA
| | - Haitao Guo
- Cancer Virology Program, UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Yufei Huang
- Cancer Virology Program, UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Electrical and Computer Engineering, Swanson School and Engineering, Pittsburgh, Pennsylvania, USA
| | - Shou-Jiang Gao
- Cancer Virology Program, UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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56
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Choday S, Ravi N, Parisapogu A, Ojinna BT, Sherpa ML. Effects of Sodium-Glucose Cotransporter Inhibitor Use in Type 2 Diabetes Mellitus Patients With Heart Failure. Cureus 2023; 15:e34687. [PMID: 36909046 PMCID: PMC9994637 DOI: 10.7759/cureus.34687] [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: 09/23/2022] [Accepted: 02/04/2023] [Indexed: 02/08/2023] Open
Abstract
The advances in the development of sodium-glucose cotransporter 2 inhibitors (SGLT2i) have expanded the variety of favorable approaches to treating diabetes mellitus. It is possible to have an improvement in insulin resistance and natriuresis by inhibiting the reabsorption of sodium and glucose at the proximal tubules in the kidney, and a decrease in cardiovascular mortality in patients with diabetes mellitus (DM). In addition, SGLT2i provides renoprotection by reducing intraglomerular higher blood pressure. The usage of SGLT2i also provides hemodynamic and metabolic benefits. SGLT2i demonstrates large cardiovascular benefits in patients both with and without diabetes, as well as in existing heart failure patients. These SGLT2i have direct and indirect effects on the kidney, likely contributing to stated cardiovascular benefits. Here we review the literature on the direct effects of SGLT2 inhibitors in diabetic patients with heart failure (HF). We assume that the benefit in cardiac cells modulated by SGLT2i is due to the inhibition of sodium transporters affecting intracellular sodium homeostasis. In conclusion, the sodium transporters in cardiac cells provide, at least partly, an example of the clinical benefits of SGLT2i observed in HF patients.
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Affiliation(s)
- Silpa Choday
- Internal Medicine, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
| | - Niriksha Ravi
- Internal Medicine and Neurology, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
| | | | - Blessing T Ojinna
- Internal Medicine and Pediatrics, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA.,General Medicine, University of Nigeria Nsukka, College of Medicine, Enugu, NGA
| | - Mingma L Sherpa
- Internal Medicine and Neurology, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
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57
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Sodium zirconium cyclosilicate and metabolic acidosis: Potential mechanisms and clinical consequences. Biomed Pharmacother 2023; 158:114197. [PMID: 36916426 DOI: 10.1016/j.biopha.2022.114197] [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: 09/06/2022] [Revised: 12/23/2022] [Accepted: 12/29/2022] [Indexed: 01/05/2023] Open
Abstract
Metabolic acidosis is frequent in chronic kidney disease (CKD) and is associated with accelerated progression of CKD, hypercatabolism, bone disease, hyperkalemia, and mortality. Clinical guidelines recommend a target serum bicarbonate ≥ 22 mmol/L, but metabolic acidosis frequently remains undiagnosed and untreated. Sodium zirconium cyclosilicate (SZC) binds potassium in the gut and is approved to treat hyperkalemia. In clinical trials with a primary endpoint of serum potassium, SZC increased serum bicarbonate, thus treating CKD-associated metabolic acidosis. The increase in serum bicarbonate was larger in patients with more severe pre-existent metabolic acidosis, was associated to decreased serum urea and was maintained for over a year of SZC therapy. SZC also decreased serum urea and increased serum bicarbonate after switching from a potassium-binding resin in normokalemic individuals. Mechanistically, these findings are consistent with SZC binding the ammonium ion (NH4+) generated from urea by gut microbial urease, preventing its absorption and, thus, preventing the liver regeneration of urea and promoting the fecal excretion of H+. This mechanism of action may potentially result in benefits dependent on corrected metabolic acidosis (e.g., improved well-being, decreased catabolism, improved CKD mineral bone disorder, better control of serum phosphate, slower progression of CKD) and dependent on lower urea levels, such as decreased protein carbamylation. A roadmap is provided to guide research into the mechanisms and clinical consequences of the impact of SZC on serum bicarbonate and urate.
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58
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Kermond R, Mallett A, McCarthy H. A clinical approach to tubulopathies in children and young adults. Pediatr Nephrol 2023; 38:651-662. [PMID: 35585366 PMCID: PMC9842573 DOI: 10.1007/s00467-022-05606-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 04/27/2022] [Accepted: 04/28/2022] [Indexed: 01/21/2023]
Abstract
Kidney tubules are responsible for the preservation of fluid, electrolyte and acid-base homeostasis via passive and active mechanisms. These physiological processes can be disrupted by inherited or acquired aetiologies. The net result is a tubulopathy. It is important to make a prompt and accurate diagnosis of tubulopathies in children and young adults. This allows timely and appropriate management, including disease-specific therapies, and avoids complications such as growth failure. Tubulopathies can present with a variety of non-specific clinical features which can be diagnostically challenging. In this review, we build from this common anatomical and physiological understanding to present a tangible appreciation of tubulopathies as they are likely to be clinically encountered among affected children and young adults.
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Affiliation(s)
- Rachael Kermond
- Department of Renal Medicine, Sydney Children’s Hospital Network, Sydney, NSW Australia
| | - Andrew Mallett
- Department of Renal Medicine, Townsville University Hospital, Douglas, QLD, Australia. .,College of Medicine and Dentistry, James Cook University, Douglas, QLD, Australia. .,Institute for Molecular Bioscience & Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia.
| | - Hugh McCarthy
- Department of Renal Medicine, Sydney Children's Hospital Network, Sydney, NSW, Australia. .,Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia. .,Centre for Kidney Research, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.
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59
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Yoo MH, Lee SJ, Kim W, Kim Y, Kim YB, Moon KS, Lee BS. Bisphenol A impairs renal function by reducing Na +/K +-ATPase and F-actin expression, kidney tubule formation in vitro and in vivo. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 246:114141. [PMID: 36206637 DOI: 10.1016/j.ecoenv.2022.114141] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 09/19/2022] [Accepted: 09/28/2022] [Indexed: 05/26/2023]
Abstract
The kidney proximal tubule is responsible for reabsorbing water and NaCl to maintain the homeostasis of the body fluids, electrolytes, and nutrients. Thus, abnormal functioning of the renal proximal tubule can lead to life-threatening imbalances. Bisphenol A (BPA) has been used for decades as a representative chemical in household plastic products, but studies on its effects on the kidney proximal tubule are insufficient. In this study, immunocytochemical and cytotoxicity tests were performed using two- and three-dimensional human renal proximal tubular epithelial cell (hRPTEC) cultures to investigate the impact of low-dose BPA (1-10 μM) exposure. BPA was found to interfere with straight tubule formation as observed by low filamentous actin formation and reduced Na+/K+-ATPase expression in the tubules of hRPTEC 3D cultures. Similar results were observed in rat pup kidneys following oral administration of 250 mg/kg BPA. Moreover, the expression of HO-1 and 8-OHdG, key markers for oxidative stress, was increased in vitro and in vivo following BPA administration, whereas that of OAT1 and OAT, important transporters of the renal proximal tubules, was not altered. Overall, no-observed-adverse-effect-level (NOAEL)-dose BPA exposure can decrease renal function by promoting abnormal tubular formation both in vitro and in vivo. Therefore, we propose that although it does not exhibit life-threatening toxicity, exposure to low levels of BPA can negatively affect homeostasis in the body by means of long-term deterioration of renal proximal tubular function in humans.
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Affiliation(s)
- Min Heui Yoo
- Department of Advanced Toxicology Research, Korea Institute of Toxicology, Daejeon, Republic of Korea.
| | - Seung-Jin Lee
- Department of Advanced Toxicology Research, Korea Institute of Toxicology, Daejeon, Republic of Korea.
| | - Woojin Kim
- Department of Advanced Toxicology Research, Korea Institute of Toxicology, Daejeon, Republic of Korea.
| | - Younhee Kim
- Department of Advanced Toxicology Research, Korea Institute of Toxicology, Daejeon, Republic of Korea.
| | - Yong-Bum Kim
- Department of Advanced Toxicology Research, Korea Institute of Toxicology, Daejeon, Republic of Korea.
| | - Kyoung-Sik Moon
- Department of Advanced Toxicology Research, Korea Institute of Toxicology, Daejeon, Republic of Korea.
| | - Byoung-Seok Lee
- Department of Advanced Toxicology Research, Korea Institute of Toxicology, Daejeon, Republic of Korea.
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60
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Rizki-Safitri A, Gupta N, Hiratsuka K, Kobayashi K, Zhang C, Ida K, Satlin LM, Morizane R. Live functional assays reveal longitudinal maturation of transepithelial transport in kidney organoids. Front Cell Dev Biol 2022; 10:978888. [PMID: 36046340 PMCID: PMC9420851 DOI: 10.3389/fcell.2022.978888] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 07/12/2022] [Indexed: 02/04/2023] Open
Abstract
Kidney organoids derived from hPSCs have opened new opportunities to develop kidney models for preclinical studies and immunocompatible kidney tissues for regeneration. Organoids resemble native nephrons that consist of filtration units and tubules, yet little is known about the functional capacity of these organoid structures. Transcriptomic analyses provide insight into maturation and transporter activities that represent kidney functions. However, functional assays in organoids are necessary to demonstrate the activity of these transport proteins in live tissues. The three-dimensional (3D) architecture adds complexity to real-time assays in kidney organoids. Here, we develop a functional assay using live imaging to assess transepithelial transport of rhodamine 123 (Rh123), a fluorescent substrate of P-glycoprotein (P-gp), in organoids affixed to coverslip culture plates for accurate real-time observation. The identity of organoid structures was probed using Lotus Tetragonolobus Lectin (LTL), which binds to glycoproteins present on the surface of proximal tubules. Within 20 min of the addition of Rh123 to culture media, Rh123 accumulated in the tubular lumen of organoids. Basolateral-to-apical accumulation of the dye/marker was reduced by pharmacologic inhibition of MDR1 or OCT2, and OCT2 inhibition reduced the Rh123 uptake. The magnitude of Rh123 transport was maturation-dependent, consistent with MDR1 expression levels assessed by RNA-seq and immunohistochemistry. Specifically, organoids on day 21 exhibit less accumulation of Rh123 in the lumen unlike later-stage organoids from day 30 of differentiation. Our work establishes a live functional assessment in 3D kidney organoids, enabling the functional phenotyping of organoids in health and disease.
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Affiliation(s)
- Astia Rizki-Safitri
- Nephrology Division, Massachusetts General Hospital, Boston, MA, United States,Department of Medicine, Harvard Medical School, Boston, MA, United States
| | - Navin Gupta
- Nephrology Division, Massachusetts General Hospital, Boston, MA, United States,Department of Medicine, Harvard Medical School, Boston, MA, United States
| | - Ken Hiratsuka
- Nephrology Division, Massachusetts General Hospital, Boston, MA, United States,Department of Medicine, Harvard Medical School, Boston, MA, United States,Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA, United States
| | - Kenichi Kobayashi
- Nephrology Division, Massachusetts General Hospital, Boston, MA, United States,Department of Medicine, Harvard Medical School, Boston, MA, United States
| | - Chengcheng Zhang
- Nephrology Division, Massachusetts General Hospital, Boston, MA, United States,Department of Medicine, Harvard Medical School, Boston, MA, United States
| | - Kazumi Ida
- Nephrology Division, Massachusetts General Hospital, Boston, MA, United States,Department of Medicine, Harvard Medical School, Boston, MA, United States
| | - Lisa M. Satlin
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York City, NY, United States
| | - Ryuji Morizane
- Nephrology Division, Massachusetts General Hospital, Boston, MA, United States,Department of Medicine, Harvard Medical School, Boston, MA, United States,Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA, United States,Harvard Stem Cell Institute, Cambridge, MA, United States,*Correspondence: Ryuji Morizane, ,
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61
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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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62
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Melena I, Piani F, Tommerdahl KL, Severn C, Chung LT, MacDonald A, Vinovskis C, Cherney D, Pyle L, Roncal-Jimenez CA, Lanaspa MA, Rewers A, van Raalte DH, Cara-Fuentes G, Parikh CR, Nelson RG, Pavkov ME, Nadeau KJ, Johnson RJ, Bjornstad P. Aminoaciduria and metabolic dysregulation during diabetic ketoacidosis: Results from the diabetic kidney alarm (DKA) study. J Diabetes Complications 2022; 36:108203. [PMID: 35523653 PMCID: PMC9119939 DOI: 10.1016/j.jdiacomp.2022.108203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 04/17/2022] [Accepted: 04/17/2022] [Indexed: 12/30/2022]
Abstract
OBJECTIVE We examined changes in the excretion of various amino acids and in glycolysis and ketogenesis-related metabolites, during and after diabetic ketoacidosis (DKA) diagnosis, in youth with known or new onset type 1 diabetes (T1D). METHODS Urine samples were collected from 40 youth with DKA (52% boys, mean age 11 ± 4 years, venous pH 7.2 ± 0.1, blood glucose 451 ± 163 mg/dL) at 3 time points: 0-8 h and 12-24 h after starting an insulin infusion, and 3 months after hospital discharge. Mixed-effects models evaluated the changes in amino acids and other metabolites in the urine. RESULTS Concentrations of urine histidine, threonine, tryptophan, and leucine per creatinine were highest at 0-8 h (148.8 ± 23.5, 59.5 ± 12.3, 15.4 ± 1.4, and 24.5 ± 2.4% of urine creatinine, respectively), and significantly decreased over 3 months (p = 0.028, p = 0.027, p = 0.019, and p < 0.0001, respectively). Urine histidine, threonine, tryptophan, and leucine per urine creatinine decreased by 10.6 ± 19.2, 0.7 ± 0.9, 1.3 ± 0.9, and 0.5 ± 0.3-fold, respectively, between 0 and 8 h and 3 months. CONCLUSIONS In our study, DKA was associated with profound aminoaciduria, suggestive of proximal tubular dysfunction analogous to Fanconi syndrome.
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Affiliation(s)
- Isabella Melena
- Department of Pediatrics, Section of Endocrinology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Federica Piani
- Department of Pediatrics, Section of Endocrinology, University of Colorado School of Medicine, Aurora, CO, USA; Department of Medicine, Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, Aurora, CO, USA; Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
| | - Kalie L Tommerdahl
- Department of Pediatrics, Section of Endocrinology, University of Colorado School of Medicine, Aurora, CO, USA; Barbara Davis Center for Diabetes, University of Colorado School of Medicine, Aurora, CO, USA
| | - Cameron Severn
- Department of Pediatrics, Section of Endocrinology, University of Colorado School of Medicine, Aurora, CO, USA; Department of Biostatistics and Informatics, Colorado School of Public Health, CO, USA
| | - Linh T Chung
- Department of Medicine, Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, Aurora, CO, USA
| | - Alexis MacDonald
- Department of Pediatrics, Section of Endocrinology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Carissa Vinovskis
- Department of Pediatrics, Section of Endocrinology, University of Colorado School of Medicine, Aurora, CO, USA
| | - David Cherney
- Department of Medicine, Division of Nephrology, University of Toronto School of Medicine, Toronto, Ontario, Canada
| | - Laura Pyle
- Department of Pediatrics, Section of Endocrinology, University of Colorado School of Medicine, Aurora, CO, USA; Department of Biostatistics and Informatics, Colorado School of Public Health, CO, USA
| | - Carlos A Roncal-Jimenez
- Department of Medicine, Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, Aurora, CO, USA
| | - Miguel A Lanaspa
- Department of Medicine, Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, Aurora, CO, USA
| | - Arleta Rewers
- Department of Pediatrics, Section of Emergency Medicine, University of Colorado School of Medicine, Aurora, CO, USA
| | - Daniël H van Raalte
- Diabetes Center, Department of Internal Medicine, Amsterdam University Medical Centers, location VUmc, Amsterdam, the Netherlands
| | - Gabriel Cara-Fuentes
- Department of Pediatrics, Section of Nephrology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Chirag R Parikh
- Department of Medicine, Division of Nephrology, Johns Hopkins University, Baltimore, MD, USA
| | - Robert G Nelson
- Chronic Kidney Disease Section, Phoenix Epidemiology and Clinical Research Branch, NIDDK, Phoenix, AZ, USA
| | - Meda E Pavkov
- Division of Diabetes Translation, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Kristen J Nadeau
- Department of Pediatrics, Section of Endocrinology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Richard J Johnson
- Department of Medicine, Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, Aurora, CO, USA
| | - Petter Bjornstad
- Department of Pediatrics, Section of Endocrinology, University of Colorado School of Medicine, Aurora, CO, USA; Department of Medicine, Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, Aurora, CO, USA.
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63
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Recommendations for evaluation and diagnosis of extra-glandular manifestations of primary sjogren syndrome: results of an epidemiologic systematic review/meta-analysis and a consensus guideline from the Brazilian Society of Rheumatology (articular, pulmonary and renal). Adv Rheumatol 2022; 62:18. [PMID: 35650656 DOI: 10.1186/s42358-022-00248-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 05/15/2022] [Indexed: 11/10/2022] Open
Abstract
Sjogren's Syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration of the exocrine glands and other organs, associated with sicca syndrome but also with systemic involvement with varying degrees of severity. Despite their importance, these systemic manifestations are not routinely evaluated and there is no homogenous approach to their diagnosis or evaluation. To close this gap, a panel of experts from the Brazilian Society of Rheumatology conducted a systematic review and meta-analysis on the identification of epidemiologic and clinical features of these manifestations and made recommendations based on the findings. Agreement between the experts was achieved using the Delphi method. The first part of this guideline summarizes the most important topics, and 11 recommendations are provided for the articular, pulmonary, and renal care of SS patients.
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Piossek F, Beneke S, Schlichenmaier N, Mucic G, Drewitz S, Dietrich DR. Physiological oxygen and co-culture with human fibroblasts facilitate in vivo-like properties in human renal proximal tubular epithelial cells. Chem Biol Interact 2022; 361:109959. [DOI: 10.1016/j.cbi.2022.109959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 04/08/2022] [Accepted: 04/12/2022] [Indexed: 11/28/2022]
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Nakashima K, Hirahara Y, Koike T, Tanaka S, Gamo K, Oe S, Hayashi S, Seki-Omura R, Nakano Y, Ohe C, Yoshida T, Kataoka Y, Tsuda M, Yamashita T, Honke K, Kitada M. Sulfatide with ceramide composed of phytosphingosine (t18:0) and 2-hydroxy fatty acids in renal intercalated cells. J Lipid Res 2022; 63:100210. [PMID: 35439525 PMCID: PMC9157219 DOI: 10.1016/j.jlr.2022.100210] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 03/28/2022] [Accepted: 04/10/2022] [Indexed: 11/27/2022] Open
Abstract
Diverse molecular species of sulfatide with differences in FA lengths, unsaturation degrees, and hydroxylation statuses are expressed in the kidneys. However, the physiological functions of specific sulfatide species in the kidneys are unclear. Here, we evaluated the distribution of specific sulfatide species in the kidneys and their physiological functions. Electron microscopic analysis of kidneys of Cst-deficient mice lacking sulfatide showed vacuolar accumulation in the cytoplasm of intercalated cells in the collecting duct, whereas the proximal and distal tubules were unchanged. Immunohistochemical analysis revealed that vacuolar H+-ATPase-positive vesicles were accumulated in intercalated cells in sulfatide-deficient kidneys. Seventeen sulfatide species were detected in the murine kidney by iMScope MALDI-MS analysis. The distribution of the specific sulfatide species was classified into four patterns. Although most sulfatide species were highly expressed in the outer medullary layer, two unique sulfatide species of m/z 896.6 (predicted ceramide structure: t18:0-C22:0h) and m/z 924.6 (predicted ceramide structure: t18:0-C24:0h) were dispersed along the collecting duct, implying expression in intercalated cells. In addition, the intercalated cell-enriched fraction was purified by fluorescence-activated cell sorting using the anti-vacuolar H+-ATPase subunit 6V0A4, which predominantly contained sulfatide species (m/z 896.6 and 924.6). The Degs2 and Fa2h genes, which are responsible for ceramide hydroxylation, were expressed in the purified intercalated cells. These results suggested that sulfatide molecular species with ceramide composed of phytosphingosine (t18:0) and 2-hydroxy FAs, which were characteristically expressed in intercalated cells, were involved in the excretion of NH3 and protons into the urine.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Takashi Yoshida
- Department of Urology and Andrology, Kansai Medical University, Hirakata, Osaka, Japan
| | - Yosky Kataoka
- Laboratory for Cellular Function Imaging, RIKEN Center for Biosystems Dynamics Research; Multi-Modal Microstructure Analysis Unit, RIKEN-JEOL Collaboration Center, Kobe, Hyogo, Japan
| | | | - Tatsuyuki Yamashita
- Department of Biochemistry, Kochi University Medical School, Nangoku, Kochi, Japan
| | - Koichi Honke
- Department of Biochemistry, Kochi University Medical School, Nangoku, Kochi, Japan
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66
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Ho KM, Morgan DJR. The Proximal Tubule as the Pathogenic and Therapeutic Target in Acute Kidney Injury. Nephron Clin Pract 2022; 146:494-502. [PMID: 35272287 DOI: 10.1159/000522341] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/27/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND In 2004, the term acute kidney injury (AKI) was introduced with the intention of broadening our understanding of rapid declines in renal function and to replace the historical terms of acute renal failure and acute tubular necrosis (ATN). Despite this evolution in terminology, the mechanisms of AKI have stayed largely elusive with the pathophysiological concepts of ATN remaining the mainstay in our understanding of AKI. SUMMARY The proximal tubule (PT), having the highest mitochondrial content in the kidney and relying heavily on oxidative phosphorylation to generate ATP, is vulnerable to ischaemic insults and mitochondrial dysfunction. Histologically, pathological changes in the PT are more consistent than changes to the glomeruli or the loop of Henle in AKI. Physiologically, activation of tubuloglomerular feedback due to PT dysfunction leads to an increase in preglomerular afferent arteriole resistance and a reduction in glomerular filtration. Pharmacologically, frusemide - a drug commonly used in the setting of oliguric AKI - is actively secreted by the PT and its diuretic effect is compromised by its failure to be secreted into the urine and thus be delivered to its site of action at the loop of Henle in AKI. Increases in the urinary, but not plasma biomarkers, of PT injury within 1 h of shock suggest that the PT as the initiation pathogenic target of AKI. KEY MESSAGE Therapeutic agents targeting specifically the PT epithelial cells, in particular its mitochondria - including amino acid ergothioneine and superoxide scavenger MitoTEMPO - show great promises in ameliorating AKI.
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Affiliation(s)
- Kwok M Ho
- Department of Intensive Care Medicine, Royal Perth Hospital, Perth, Washington, Australia.,Medical School, University of Western Australia, Perth, Washington, Australia.,School of Veterinary & Life Sciences, Murdoch University, Perth, Washington, Australia
| | - David J R Morgan
- Department of Intensive Care Medicine, Fiona Stanley Hospital, Perth, Washington, Australia
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Aronson PS. New Insights into the Pivotal Roles of Claudins in Proximal Tubule Electrolyte Reabsorption. J Am Soc Nephrol 2022; 33:659-661. [PMID: 35264457 PMCID: PMC8970453 DOI: 10.1681/asn.2022020157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- Peter S Aronson
- Departments of Internal Medicine and of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
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68
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Abstract
An exploration of the normal limits of physiologic responses and how these responses are lost when the kidney is injured rarely occurs in clinical practice. However, the differences between "resting" and "stressed" responses identify an adaptive reactiveness that is diminished before baseline function is impaired. This functional reserve is important in the evaluation of prognosis and progression of kidney disease. Here, we discuss stress tests that examine protein-induced hyperfiltration, proximal tubular secretion, urea-selective concentration defects, and acid retention. We discuss diseases in which these tests have been used to diagnose subclinical injury. The study and follow-up of abnormal functional reserve may add considerable understanding to the natural history of CKD.
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Affiliation(s)
- Armando Armenta
- Department of Nephrology, National Institute of Cardiology “Ignacio Chavez,” Mexico City, Mexico
| | - Magdalena Madero
- Department of Nephrology, National Institute of Cardiology “Ignacio Chavez,” Mexico City, Mexico
| | - Bernardo Rodriguez-Iturbe
- Department of Nephrology, National Institute of Cardiology "Ignacio Chavez," Mexico City, Mexico .,Department of Nephrology and Mineral Metabolism, National Institute of Health Sciences and Nutrition "Salvador Zubirán," Mexico City, Mexico
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Mathur VS, Wesson DE, Tangri N, Li E, Bushinsky DA. Effects of veverimer on serum bicarbonate and physical function in women with chronic kidney disease and metabolic acidosis: a subgroup analysis from a randomised, controlled trial. BMC Nephrol 2022; 23:82. [PMID: 35216581 PMCID: PMC8881824 DOI: 10.1186/s12882-022-02690-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 01/28/2022] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Globally, the prevalence of chronic kidney disease (CKD) is higher in women than in men; however, women have been historically under-represented in nephrology clinical trials. Metabolic acidosis increases risk of progressive loss of kidney function, causes bone demineralization and muscle protein catabolism, and may be more consequential in women given their lower bone and muscle mass. Veverimer, an investigational, non-absorbed polymer that binds and removes gastrointestinal hydrochloric acid, is being developed as treatment for metabolic acidosis. METHODS This was a Phase 3, multicenter, randomised, blinded, placebo-controlled trial in 196 patients with CKD (eGFR: 20-40 mL/min/1.73 m2) and metabolic acidosis who were treated for up to 1 year with veverimer or placebo. We present the findings from a pre-specified subgroup analysis evaluating the effects of veverimer on metabolic acidosis and physical function among women (N = 77) enrolled in this trial. RESULTS At week 52, women treated with veverimer had a greater increase in mean (± standard error) serum bicarbonate than the placebo group (5.4 [0.5] vs. 2.2 [0.6] mmol/L; P < 0.0001). Physical Function reported by patients on the Kidney Disease and Quality of Life - Physical Function Domain, a measure that includes items related to walking, stair climbing, carrying groceries and other activities improved significantly in women randomized to veverimer vs placebo (+ 13.2 vs. -5.2, respectively, P < 0.0031). Objectively measured performance time on the repeated chair stand test also improved significantly in the veverimer group vs. placebo (P = 0.0002). CONCLUSIONS Veverimer was effective in treating metabolic acidosis in women with CKD, and significantly improved how they felt and functioned. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT03390842 . Registered on January 4, 2018.
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Affiliation(s)
- Vandana S Mathur
- MathurConsulting LLC, 25 Upenuf Road, Suite 100, Woodside, CA, 94062-2633, USA.
| | - Donald E Wesson
- Texas A&M Health Sciences Center College of Medicine, Dallas, TX, USA
- Donald E Wesson Consulting, LLC, Dallas, TX, USA
| | | | | | - David A Bushinsky
- University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
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Abstract
The kidney maintains electrolyte, water, and acid-base balance, eliminates foreign and waste compounds, regulates blood pressure, and secretes hormones. There are at least 16 different highly specialized epithelial cell types in the mammalian kidney. The number of specialized endothelial cells, immune cells, and interstitial cell types might even be larger. The concerted interplay between different cell types is critical for kidney function. Traditionally, cells were defined by their function or microscopical morphological appearance. With the advent of new single-cell modalities such as transcriptomics, epigenetics, metabolomics, and proteomics we are entering into a new era of cell type definition. This new technological revolution provides new opportunities to classify cells in the kidney and understand their functions.
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Affiliation(s)
- Michael S Balzer
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, Pennsylvania, USA;
- Institute of Diabetes Obesity and Metabolism, University of Pennsylvania, Philadelphia, Philadelphia, USA
| | - Tibor Rohacs
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Katalin Susztak
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, Pennsylvania, USA;
- Institute of Diabetes Obesity and Metabolism, University of Pennsylvania, Philadelphia, Philadelphia, USA
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71
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Itoh H, Tanaka M. “Greedy Organs Hypothesis” for sugar and salt in the pathophysiology of non-communicable diseases in relation to sodium-glucose co-transporters in the intestines and the kidney. Metabol Open 2022; 13:100169. [PMID: 35198947 PMCID: PMC8844901 DOI: 10.1016/j.metop.2022.100169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/07/2022] [Accepted: 02/07/2022] [Indexed: 11/05/2022] Open
Abstract
Deposition of visceral fat and insulin resistance play central role in the development of non-communicable diseases (NCDs) including obesity, hypertension and type 2 diabetes. However, we shed more light upon the intestines and the kidney as a strong driver of NCDs. Based upon unexpected outcomes of clinical trials using sodium-glucose cotransporter (SGLT) 2 inhibitors to demonstrate their actions for not only body weight reduction and blood glucose fall but also remarkable cardiorenal protection, we speculate that hyperfunction of the intestines and the kidney is one of critical contributing factors for initiation of NCDs. By detecting high amount of glucose and sodium chloride around them by sweet/salt taste sensors, the intestines and the kidney are designed to (re)absorb these nutrients by up-regulating SGLT1 or SGLT2. We designate these hyperfunctioning organs for nutrient uptake as “greedy organs”. The greedy organs can induce NCDs (“greedy organ hypothesis”). SGLTs are regulated by glucose and sodium chloride, and SGLTs or other genes can be “greedy genes.” Regulating factors for greedy organs are renin-angiotensin system, renal sympathetic nervous activity, gut inflammation/microbiota or oxidative stress. Mitigation of organ greediness by SGLT2 inhibitors, ketone bodies, bariatric surgery, and regular lifestyle to keep rhythmicity of biological clock are promising. We propose the concept of “Greedy Organs” hypothesis as a possible cause of NCDs. Clinical implication of greedy kidney is supported by the effect of SGLT2 inhibitors. The significance of greedy intestines is suggested by the effect of bariatric surgery. The intestines and kidney become hyperactive through upregulation of SGLT1 or 2. To mitigate “greedy organs” should be a promising strategy against NCDs.
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Evolving concepts of TRPV4 in controlling flow-sensitivity of the renal nephron. CURRENT TOPICS IN MEMBRANES 2022; 89:75-94. [DOI: 10.1016/bs.ctm.2022.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Ash SR, Batlle D, Kendrick J, Oluwatosin Y, Pottorf W, Brahmbhatt Y, Guerrieri E, Fried L. Effect of Sodium Zirconium Cyclosilicate on Serum Potassium and Bicarbonate in Patients with Hyperkalemia and Metabolic Acidosis Associated with Chronic Kidney Disease: Rationale and Design of the NEUTRALIZE Study. Nephron Clin Pract 2022; 146:599-609. [PMID: 35462371 PMCID: PMC9808635 DOI: 10.1159/000523911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 02/27/2022] [Indexed: 01/07/2023] Open
Abstract
INTRODUCTION Sodium zirconium cyclosilicate (SZC) is a selective potassium (K+) binder for hyperkalemia management that provides rapid and sustained correction of hyperkalemia. The NEUTRALIZE study is investigating whether SZC, in addition to correcting hyperkalemia and maintaining normal serum K+, can provide sustained increases in serum bicarbonate (HCO3-) in patients with hyperkalemia and metabolic acidosis associated with chronic kidney disease (CKD). METHODS This is a prospective, randomized, double-blind, placebo-controlled phase 3b study of US adults with stage 3-5 CKD not on dialysis with hyperkalemia (K+ >5.0-≤5.9 mmol/L) and low-serum HCO3- (16-20 mmol/L). In the open-label correction phase, all eligible patients receive SZC 10 g three times daily for up to 48 h. Patients who achieve normokalemia (K+ ≥3.5-≤5.0 mmol/L) are then randomized 1:1 to once-daily SZC 10 g or placebo for a 4-week, double-blind, placebo-controlled maintenance phase. The primary endpoint is the proportion of patients with normokalemia at the end of treatment (EOT) without rescue therapy for hyperkalemia. Key secondary endpoints include mean change in serum HCO3-, the proportion of patients with an increase in serum HCO3- of ≥2 or ≥3 mmol/L without rescue therapy for metabolic acidosis, and the proportion of patients with serum HCO3- ≥22 mmol/L at EOT. CONCLUSIONS NEUTRALIZE will establish whether SZC can provide sustained increases in serum HCO3- while lowering serum K+ in patients with hyperkalemia and CKD-associated metabolic acidosis and may provide insights on the mechanism(s) underlying the increased serum HCO3- with SZC treatment.
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Affiliation(s)
- Stephen R Ash
- Nephrology Department, Indiana University Health Arnett, Lafayette, Indiana, USA
| | - Daniel Batlle
- Division of Nephrology and Hypertension, Department of Medicine, The Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Jessica Kendrick
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | | | | | | | | | - Linda Fried
- Veterans Affairs Pittsburgh Healthcare System and University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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Induction of FGF23-related hypophosphatemic osteomalacia by alcohol consumption. Bone Rep 2021; 15:101144. [PMID: 34901334 PMCID: PMC8640868 DOI: 10.1016/j.bonr.2021.101144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/07/2021] [Accepted: 10/12/2021] [Indexed: 02/03/2023] Open
Abstract
Context Fibroblast growth factor (FGF) 23 is a hormone that regulates serum phosphate levels, the excess action of which causes chronic hypophosphatemic rickets/osteomalacia. To date, there are only two identified causes of acquired FGF23-related hypophosphatemic osteomalacia: tumor-induced osteomalacia (TIO) and osteomalacia induced by the intravenous infusion of some forms of iron preparations. In the current study, two cases of FGF23-related hypophosphatemia probably induced by chronic alcohol consumption were first introduced. Case description Case 1 and case 2 had been drinking high amounts of alcohol for more than twenty years until they were admitted to the hospital. Case 1 was a 43-year-old man with progressive worsening multiple pains and muscle weakness who exhibited chronic hypophosphatemia with increased intact FGF23 levels. A week after admission, the serum phosphate level recovered to the reference range, and the intact FGF23 level declined. Case 1 resumed drinking after discharge, and hypophosphatemia concomitant with high intact FGF23 levels recurred. The alleviation of FGF23-related hypophosphatemia was observed each time he temporarily abstained from drinking for a short period. Case 2 was a 60-year-old man with recurrent fractures and exacerbation of pain in multiple joints who also exhibited hypophosphatemia with increased intact FGF23 levels. After admission, the serum phosphate level gradually increased to the lower limit of the normal range. The intact FGF23 level decreased, but it was still higher than 30 pg/ml, and causative FGF23-producing tumors were not identified even with thorough examinations, including somatostatin receptor scintigraphy, fluorine-18-fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG-PET/CT) and systemic venous FGF23 sampling. He completely abstained from alcohol after discharge. Along with the serum phosphate level, intact FGF23 was subsequently decreased and had been normalized for 5 months. Both patients had no genetic mutation related to hereditary FGF23-related hypophosphatemic rickets/osteomalacia, including autosomal dominant hypophosphatemic rickets/osteomalacia (ADHR). Conclusion Two cases of FGF23-related hypophosphatemia probably induced by alcohol were first introduced in this study. Identifying this reversible condition among acquired FGF23-related hypophosphatemic osteomalacia is critical to obtain better patient outcomes and save medical resources. This condition is similar to iron infusion-induced FGF23-related hypophosphatemia in terms of the dysregulation of FGF23 due to exogenous factors. Future research to elucidate the precise mechanism of these conditions is warranted. Two adults with acquired FGF23-related hypophosphatemic osteomalacia were studied. Tumor-induced osteomalacia was suspected initially, but no tumor was identified. Cessation of alcohol led to recovery from FGF23-related hypophosphatemia. Alcohol is a well-recognized cause of hypophosphatemia, but osteomalacia is uncommon. Alcohol-induced FGF23-related osteomalacia is a totally new and distinct phenomenon.
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Harris AN, Castro RA, Lee HW, Verlander JW, Weiner ID. Role of the renal androgen receptor in sex differences in ammonia metabolism. Am J Physiol Renal Physiol 2021; 321:F629-F644. [PMID: 34605272 PMCID: PMC8616601 DOI: 10.1152/ajprenal.00260.2021] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 11/22/2022] Open
Abstract
There are sex differences in renal ammonia metabolism and structure, many of which are mediated by testosterone. The goal of the present study was to determine the role of renal expression of testosterone's canonical receptor, androgen receptor (AR), in these sexual dimorphisms. We studied mice with kidney-specific AR deletion [KS-AR-knockout (KO)] generated using Cre/loxP techniques; control mice were Cre-negative littermates (wild type). In male but not female mice, KS-AR-KO increased ammonia excretion, which eliminated sex differences. Although renal structural size typically parallel ammonia excretion, KS-AR-KO decreased kidney size, cortical proximal tubule volume density, and cortical proximal tubule cell height in males-neither were altered in females and collecting duct volume density was unaltered in both sexes. Analysis of key protein involved in ammonia handling showed in male mice that KS-AR-KO increased both phosphoenolpyruvate carboxykinase (PEPCK) and Na+-K+-2Cl- cotransporter (NKCC2) expression and decreased Na+/H+ exchanger isoform 3 (NHE3) and electrogenic Na+-bicarbonate cotransporter 1 (NBCe1)-A expression. In female mice, KS-AR-KO did not alter these parameters. These effects occurred even though KS-AR-KO did not alter plasma testosterone, food intake, or serum Na+, K+, or [Formula: see text] significantly in either sex. In conclusion, AR-dependent signaling pathways in male, but not female, kidneys regulate PEPCK and NKCC2 expression and lead to the sexual differences in ammonia excretion. Opposing effects on NHE3 and NBCe1-A expression likely limit the magnitude of ammonia excretion changes. As AR is not present in the thick ascending limb, the effect of KS-AR-KO on NKCC2 expression is indirect. Finally, AR mediates the greater kidney size and proximal tubule volume density in male compared with female mice.NEW & NOTEWORTHY Sexual dimorphisms in ammonia metabolism involve androgen receptor (AR)-dependent signaling pathways in male, but not female, kidneys that lead to altered proximal tubule (PT), phosphoenolpyruvate carboxykinase, and thick ascending limb Na+-K+-2Cl- cotransporter expression. Adaptive responses in Na+/H+ exchanger 3 and electrogenic Na+-bicarbonate cotransporter 1-A expression limit the magnitude of the effect on ammonia excretion. Finally, the greater kidney size and PT volume density in male mice is the result of PT androgen signaling through AR.
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Affiliation(s)
- Autumn N Harris
- Department of Small Animal Clinical Science, University of Florida College of Veterinary Medicine, Gainesville, Florida
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Rebeca A Castro
- Department of Small Animal Clinical Science, University of Florida College of Veterinary Medicine, Gainesville, Florida
| | - Hyun-Wook Lee
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Jill W Verlander
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - I David Weiner
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
- Nephrology and Hypertension Section, Gainesville Veterans Administration Medical Center, Gainesville, Florida
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Atypical Renal Clearance of Nanoparticles Larger Than the Kidney Filtration Threshold. Int J Mol Sci 2021; 22:ijms222011182. [PMID: 34681853 PMCID: PMC8537351 DOI: 10.3390/ijms222011182] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 12/12/2022] Open
Abstract
In recent years, several publications reported that nanoparticles larger than the kidney filtration threshold were found intact in the urine after being injected into laboratory mice. This theoretically should not be possible, as it is widely known that the kidneys prevent molecules larger than 6–8 nm from escaping into the urine. This is interesting because it implies that some nanoparticles can overcome the size limit for renal clearance. What kinds of nanoparticles can “bypass” the glomerular filtration barrier and cross into the urine? What physical and chemical characteristics are essential for nanoparticles to have this ability? And what are the biomolecular and cellular mechanisms that are involved? This review attempts to answer those questions and summarize known reports of renal-clearable large nanoparticles.
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Ngo J, Osto C, Villalobos F, Shirihai OS. Mitochondrial Heterogeneity in Metabolic Diseases. BIOLOGY 2021; 10:biology10090927. [PMID: 34571805 PMCID: PMC8470264 DOI: 10.3390/biology10090927] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 09/03/2021] [Accepted: 09/08/2021] [Indexed: 11/16/2022]
Abstract
Simple Summary Often times mitochondria within a single cell are depicted as homogenous entities both morphologically and functionally. In normal and diseased states, mitochondria are heterogeneous and display distinct functional properties. In both cases, mitochondria exhibit differences in morphology, membrane potential, and mitochondrial calcium levels. However, the degree of heterogeneity is different during disease; or rather, heterogeneity at the physiological state stems from physically distinct mitochondrial subpopulations. Overall, mitochondrial heterogeneity is both beneficial and detrimental to the cellular system; protective in enabling cellular adaptation to biological stress or detrimental in inhibiting protective mechanisms. Abstract Mitochondria have distinct architectural features and biochemical functions consistent with cell-specific bioenergetic needs. However, as imaging and isolation techniques advance, heterogeneity amongst mitochondria has been observed to occur within the same cell. Moreover, mitochondrial heterogeneity is associated with functional differences in metabolic signaling, fuel utilization, and triglyceride synthesis. These phenotypic associations suggest that mitochondrial subpopulations and heterogeneity influence the risk of metabolic diseases. This review examines the current literature regarding mitochondrial heterogeneity in the pancreatic beta-cell and renal proximal tubules as they exist in the pathological and physiological states; specifically, pathological states of glucolipotoxicity, progression of type 2 diabetes, and kidney diseases. Emphasis will be placed on the benefits of balancing mitochondrial heterogeneity and how the disruption of balancing heterogeneity leads to impaired tissue function and disease onset.
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Affiliation(s)
- Jennifer Ngo
- Department of Medicine, Division of Endocrinology, David Geffen School of Medicine at UCLA, 650 Charles E. Young Drive East, Los Angeles, CA 90095, USA; (J.N.); (C.O.); (F.V.)
- Department of Chemistry and Biochemistry, University of California, 607 Charles E. Young Drive East, Los Angeles, CA 90095, USA
- Metabolism Theme, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Corey Osto
- Department of Medicine, Division of Endocrinology, David Geffen School of Medicine at UCLA, 650 Charles E. Young Drive East, Los Angeles, CA 90095, USA; (J.N.); (C.O.); (F.V.)
- Metabolism Theme, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, 650 Charles E. Young Drive East, Los Angeles, CA 90095, USA
| | - Frankie Villalobos
- Department of Medicine, Division of Endocrinology, David Geffen School of Medicine at UCLA, 650 Charles E. Young Drive East, Los Angeles, CA 90095, USA; (J.N.); (C.O.); (F.V.)
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA
| | - Orian S. Shirihai
- Department of Medicine, Division of Endocrinology, David Geffen School of Medicine at UCLA, 650 Charles E. Young Drive East, Los Angeles, CA 90095, USA; (J.N.); (C.O.); (F.V.)
- Metabolism Theme, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, 650 Charles E. Young Drive East, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
- Correspondence:
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Metabolic Reprogramming and Host Tolerance: A Novel Concept to Understand Sepsis-Associated AKI. J Clin Med 2021; 10:jcm10184184. [PMID: 34575294 PMCID: PMC8471000 DOI: 10.3390/jcm10184184] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 12/26/2022] Open
Abstract
Acute kidney injury (AKI) is a frequent complication of sepsis that increases mortality and the risk of progression to chronic kidney disease. However, the mechanisms leading to sepsis-associated AKI are still poorly understood. The recognition that sepsis induces organ dysfunction in the absence of overt necrosis or apoptosis has led to the consideration that tubular epithelial cells (TEC) may deploy defense mechanisms to survive the insult. This concept dovetails well with the notion that the defense against infection does not only depend on the capacity of the immune system to limit the microbial load (known as resistance), but also on the capacity of cells and tissues to limit tissue injury (known as tolerance). In this review, we discuss the importance of TEC metabolic reprogramming as a defense strategy during sepsis, and how this cellular response is likely to operate through a tolerance mechanism. We discuss the fundamental role of specific regulatory nodes and of mitochondria in orchestrating this response, and how this opens avenues for the exploration of targeted therapeutic strategies to prevent or treat sepsis-associated AKI.
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79
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Denis C, Lasfargues C, Buffin-Meyer B. Exploration of simulated urine sample biochemistry for the diagnosis of diseases: A laboratory practical exercise. BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION : A BIMONTHLY PUBLICATION OF THE INTERNATIONAL UNION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 49:768-781. [PMID: 34019323 DOI: 10.1002/bmb.21527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 03/08/2021] [Accepted: 05/03/2021] [Indexed: 06/12/2023]
Abstract
The practical work described here is designed for third-year bachelor students in Life Sciences attending a kidney physiology course. It illustrates how urinary biochemistry can be used for a medical diagnosis. Students have to measure glucose, proteins, and creatinine concentrations in three simulated urine samples. First, they independently elaborate detailed protocols from the biochemical kit's technical sheets. Second, after correction of the protocols by the teacher, they perform the biochemical assays. Finally, students write a report in which they interpret the biochemical data and use them in the context of histological images assigned to each urine sample. With their results, their theoretical background and scientific articles supplied by the teacher, they establish the diagnosis indicating which patients are diseased and from which disease they are suffering (diabetes without nephropathy, diabetic nephropathy or hypertensive nephropathy). The originality of this practical work is to give student autonomy from the start of the project by requiring them to write the protocols, and determine the diagnosis by themselves. Simple and inexpensive, this practical forces students to mobilize their knowledge in renal physiology and pathophysiology as well as those acquired in other disciplines such as biochemistry or cellular biology. A survey conducted on two classes of students confirmed that this type of training helps students to better understand renal physiology, to realize the importance of interdisciplinarity (biochemistry, histology, and physiology) and to develop confidence in their ability to work independently.
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Affiliation(s)
- Colette Denis
- Pôle de Physiologie Animale, Département Biologie et Géosciences, Faculté des Sciences et d'Ingénierie, Université Paul Sabatier/Toulouse III, Université Fédérale Toulouse Midi-Pyrénées, Toulouse, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1297, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Charline Lasfargues
- Pôle de Physiologie Animale, Département Biologie et Géosciences, Faculté des Sciences et d'Ingénierie, Université Paul Sabatier/Toulouse III, Université Fédérale Toulouse Midi-Pyrénées, Toulouse, France
| | - Bénédicte Buffin-Meyer
- Pôle de Physiologie Animale, Département Biologie et Géosciences, Faculté des Sciences et d'Ingénierie, Université Paul Sabatier/Toulouse III, Université Fédérale Toulouse Midi-Pyrénées, Toulouse, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1297, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
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Muiru AN, Scherzer R, Ascher SB, Jotwani V, Grunfeld C, Shigenaga J, Spaulding KA, Ng DK, Gustafson D, Spence AB, Sharma A, Cohen MH, Parikh CR, Ix JH, Estrella MM, Shlipak MG. Associations of CKD risk factors and longitudinal changes in urine biomarkers of kidney tubules among women living with HIV. BMC Nephrol 2021; 22:296. [PMID: 34461840 PMCID: PMC8406753 DOI: 10.1186/s12882-021-02508-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 08/16/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Novel urine biomarkers have enabled the characterization of kidney tubular dysfunction and injury among persons living with HIV, a population at an increased risk of kidney disease. Even though several urine biomarkers predict progressive kidney function decline, antiretroviral toxicity, and mortality in the setting of HIV infection, the relationships among the risk factors for chronic kidney disease (CKD) and urine biomarkers are unclear. METHODS We assessed traditional and infection-related CKD risk factors and measured 14 urine biomarkers at baseline and at follow-up among women living with HIV in the Women's Interagency Health Study (WIHS). We then used simultaneously adjusted multivariable linear regression models to evaluate the associations of CKD risk factors with longitudinal changes in biomarker levels. RESULTS Of the 647 women living with HIV in this analysis, the majority (67%) were Black, the median age was 45 years and median follow-up time was 2.5 years. Each traditional and infection-related CKD risk factor was associated with a unique set of changes in urine biomarkers. For example, baseline hemoglobin a1c was associated with worse tubular injury (higher interleukin [IL]-18), proximal tubular reabsorptive dysfunction (higher α1-microglobulin), tubular reserve (lower uromodulin) and immune response to injury (higher chitinase-3-like protein-1 [YKL-40]). Furthermore, increasing hemoglobin a1c at follow-up was associated with further worsening of tubular injury (higher kidney injury molecule-1 [KIM-1] and IL-18), as well as higher YKL-40. HCV co-infection was associated with worsening proximal tubular reabsorptive dysfunction (higher β2-microglobulin [β2m]), and higher YKL-40, whereas HIV viremia was associated with worsening markers of tubular and glomerular injury (higher KIM-1 and albuminuria, respectively). CONCLUSIONS CKD risk factors are associated with unique patterns of biomarker changes among women living with HIV, suggesting that serial measurements of multiple biomarkers may help in detecting and monitoring kidney disease in this setting.
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Affiliation(s)
- Anthony N Muiru
- Kidney Health Research Collaborative, Department of Medicine, San Francisco Veterans Affairs Health Care System and University of California, San Francisco, CA, USA.
- Department of Medicine, Division of Nephrology, University of California, 533 Parnassus Avenue, U404, Box 0532, San Francisco, CA, 94143, USA.
| | - Rebecca Scherzer
- Kidney Health Research Collaborative, Department of Medicine, San Francisco Veterans Affairs Health Care System and University of California, San Francisco, CA, USA
| | - Simon B Ascher
- Kidney Health Research Collaborative, Department of Medicine, San Francisco Veterans Affairs Health Care System and University of California, San Francisco, CA, USA
- Division of Hospital Medicine, University of California Davis, Sacramento, CA, USA
| | - Vasantha Jotwani
- Kidney Health Research Collaborative, Department of Medicine, San Francisco Veterans Affairs Health Care System and University of California, San Francisco, CA, USA
- Department of Medicine, Division of Nephrology, University of California, 533 Parnassus Avenue, U404, Box 0532, San Francisco, CA, 94143, USA
| | - Carl Grunfeld
- Kidney Health Research Collaborative, Department of Medicine, San Francisco Veterans Affairs Health Care System and University of California, San Francisco, CA, USA
| | - Judy Shigenaga
- Kidney Health Research Collaborative, Department of Medicine, San Francisco Veterans Affairs Health Care System and University of California, San Francisco, CA, USA
| | - Kimberly A Spaulding
- Kidney Health Research Collaborative, Department of Medicine, San Francisco Veterans Affairs Health Care System and University of California, San Francisco, CA, USA
| | - Derek K Ng
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Deborah Gustafson
- Department of Neurology, The State University of New York Downstate Health Sciences University, Brooklyn, New York, USA
| | - Amanda B Spence
- Division of Infectious Diseases, Department of Medicine, Georgetown University Medical Center, Washington, DC, USA
| | - Anjali Sharma
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Mardge H Cohen
- Department of Medicine, Stroger Hospital and Rush University, Chicago, IL, USA
| | - Chirag R Parikh
- Division of Nephrology, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Joachim H Ix
- Division of Nephrology-Hypertension, University of California, San Diego, CA, USA
| | - Michelle M Estrella
- Kidney Health Research Collaborative, Department of Medicine, San Francisco Veterans Affairs Health Care System and University of California, San Francisco, CA, USA
- Department of Medicine, Division of Nephrology, University of California, 533 Parnassus Avenue, U404, Box 0532, San Francisco, CA, 94143, USA
| | - Michael G Shlipak
- Kidney Health Research Collaborative, Department of Medicine, San Francisco Veterans Affairs Health Care System and University of California, San Francisco, CA, USA
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81
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Liu J, Tian J, Sodhi K, Shapiro JI. The Na/K-ATPase Signaling and SGLT2 Inhibitor-Mediated Cardiorenal Protection: A Crossed Road? J Membr Biol 2021; 254:513-529. [PMID: 34297135 PMCID: PMC8595165 DOI: 10.1007/s00232-021-00192-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/06/2021] [Indexed: 12/17/2022]
Abstract
In different large-scale clinic outcome trials, sodium (Na+)/glucose co-transporter 2 (SGLT2) inhibitors showed profound cardiac- and renal-protective effects, making them revolutionary treatments for heart failure and kidney disease. Different theories are proposed according to the emerging protective effects other than the original purpose of glucose-lowering in diabetic patients. As the ATP-dependent primary ion transporter providing the Na+ gradient to drive other Na+-dependent transporters, the possible role of the sodium–potassium adenosine triphosphatase (Na/K-ATPase) as the primary ion transporter and its signaling function is not explored.
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Affiliation(s)
- Jiang Liu
- Department of Biomedical Sciences, JCE School of Medicine, Marshall University, Huntington, WV, USA.
| | - Jiang Tian
- Department of Biomedical Sciences, JCE School of Medicine, Marshall University, Huntington, WV, USA
| | - Komal Sodhi
- Department of Surgery, JCE School of Medicine, Marshall University, Huntington, WV, USA
| | - Joseph I Shapiro
- Departments of Medicine, JCE School of Medicine, Marshall University, Huntington, WV, USA
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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: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [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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Mathur VS, Li E, Wesson DE. Effects of veverimer on serum bicarbonate and physical function in diabetic patients with chronic kidney disease and metabolic acidosis: subgroup analysis from a randomized, controlled trial. Nephrol Dial Transplant 2021; 37:1302-1309. [PMID: 34240198 PMCID: PMC9217650 DOI: 10.1093/ndt/gfab209] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Indexed: 11/30/2022] Open
Abstract
Background Metabolic acidosis is a complication of chronic kidney disease (CKD) that increases risk of CKD progression, and causes bone demineralization and muscle protein catabolism. Patients with diabetes are prone to metabolic acidosis and functional limitations that decrease quality of life. Veverimer, an investigational, non-absorbed polymer that binds and removes gastrointestinal hydrochloric acid, is being developed as treatment for metabolic acidosis. This post hoc subgroup analysis evaluated effects of veverimer on metabolic acidosis and physical function among patients with diabetes. Methods This was a Phase 3, multicenter, randomized, blinded, placebo-controlled trial in 196 patients with CKD (estimated glomerular filtration rate 20–40 mL/min/1.73 m2) and metabolic acidosis who were treated for up to 1 year with veverimer or placebo. Results At Week 52, veverimer-treated patients with diabetes (n = 70), had a significantly greater increase in mean serum bicarbonate than the placebo group (n = 57) (4.4 versus 2.9 mmol/L, P < 0.05). Patient-reported limitations of physical function on the Kidney Disease and Quality of Life-Physical Function Domain (e.g. walking several blocks and climbing a flight of stairs) improved significantly in the veverimer versus placebo group (+12.5 versus +0.3, respectively, P < 0.001) as did objective physical performance on the repeated chair stand test (P < 0.0001). Conclusions Few interventions for patients with diabetes and CKD have successfully improved quality of life or physical functioning. Our study demonstrated that veverimer effectively treated metabolic acidosis in patients with diabetes and CKD, and significantly improved how these patients felt and functioned.
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Affiliation(s)
| | | | - Donald E Wesson
- Texas A&M Health Sciences Center College of Medicine, Dallas, TX; Donald E Wesson Consulting, LLC, Dallas, TX, USA
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84
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Abstract
TRPC3 is a Ca2+-permeable cation channel commonly activated by the G-protein coupled receptors (GPCR) and mechanical distortion of the plasma membrane. TRPC3-mediated Ca2+ influx has been implicated in a variety of signaling processes in both excitable and non-excitable cells. Kidneys play a commanding role in maintaining whole-body homeostasis and setting blood pressure. TRPC3 is expressed abundantly in the renal vasculature and in epithelial cells, where it is well positioned to mediate signaling and transport functions in response to GPCR-dependent endocrine stimuli. In addition, TRPC3 could be activated by mechanical forces resulting from dynamic changes in the renal tubule fluid flow and osmolarity. This review critically analyzes the available published evidence of the physiological roles of TRPC3 in different parts of the kidney and describes the pathophysiological ramifications of TRPC3 ablation. We also speculate how this evidence could be further translated into the clinic.
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Affiliation(s)
- Naghmeh Hassanzadeh Khayyat
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston , Houston, TX, USA
| | - Viktor N Tomilin
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston , Houston, TX, USA
| | - Oleg Zaika
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston , Houston, TX, USA
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston , Houston, TX, USA
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85
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Nosrati H, Hamzepoor M, Sohrabi M, Saidijam M, Assari MJ, Shabab N, Gholami Mahmoudian Z, Alizadeh Z. The potential renal toxicity of silver nanoparticles after repeated oral exposure and its underlying mechanisms. BMC Nephrol 2021; 22:228. [PMID: 34144690 PMCID: PMC8212496 DOI: 10.1186/s12882-021-02428-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Accepted: 05/28/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Silver nanoparticles (AgNPs) can accumulate in various organs after oral exposure. The main objective of the current study is to evaluate the renal toxicity induced by AgNPs after repeated oral exposure and to determine the relevant molecular mechanisms. METHODS In this study, 40 male Wistar rats were treated with solutions containing 30, 125, 300, and 700 mg/kg of AgNPs. After 28 days of exposure, histopathological changes were assessed using hematoxylin-eosin (H&E), Masson's trichrome, and periodic acid-Schiff (PAS) staining. Apoptosis was quantified by TUNEL and immunohistochemistry of caspase-3, and the level of expression of the mRNAs of growth factors was determined using RT-PCR. RESULTS Histopathologic examination revealed degenerative changes in the glomeruli, loss of tubular architecture, loss of brush border, and interrupted tubular basal laminae. These changes were more noticeable in groups treated with 30 and 125 mg/kg. The collagen intensity increased in the group treated with 30 mg/kg in both the cortex and the medulla. Apoptosis was much more evident in middle-dose groups (i.e., 125 and 300 mg/kg). The results of RT-PCR indicated that Bcl-2 and Bax mRNAs upregulated in the treated groups (p < 0.05). Moreover, the data related to EGF, TNF-α, and TGF-β1 revealed that AgNPs induced significant changes in gene expression in the groups treated with 30 and 700 mg/kg compared to the control group. CONCLUSION Our observations showed that AgNPs played a critical role in in vivo renal toxicity.
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Affiliation(s)
- Hamed Nosrati
- Department of Anatomical Sciences, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Manijeh Hamzepoor
- Department of Anatomical Sciences, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Maryam Sohrabi
- Department of Anatomical Sciences, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Massoud Saidijam
- Research Center for Molecular Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Mohammad Javad Assari
- Research Center for Health Sciences, School of Public Health, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Nooshin Shabab
- Research Center for Molecular Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Zahra Gholami Mahmoudian
- Department of Anatomical Sciences, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Zohreh Alizadeh
- Endometrium and Endometriosis Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.
- Department of Anatomical Sciences, Hamadan University of Medical Sciences, Shahid Fahmideh Ave., P.O. Box. 65178-518, Hamadan, Iran.
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86
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Rianto F, Hoang T, Revoori R, Sparks MA. Angiotensin receptors in the kidney and vasculature in hypertension and kidney disease. Mol Cell Endocrinol 2021; 529:111259. [PMID: 33781840 DOI: 10.1016/j.mce.2021.111259] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 01/05/2021] [Accepted: 03/20/2021] [Indexed: 12/24/2022]
Abstract
Kidney disease, blood pressure determination, hypertension pathogenesis, and the renin-angiotensin system (RAS) are inextricably linked. Hence, understanding the RAS is pivotal to unraveling the pathophysiology of hypertension and the determinants to maintaining normal blood pressure. The RAS has been the subject of intense investigation for over a century. Moreover, medications that block the RAS are mainstay therapies in clinical medicine and have been shown to reduce morbidity and mortality in patients with diabetes, cardiovascular, and kidney diseases. The main effector peptide of the RAS is the interaction of the octapeptide- Ang II with its receptor. The type 1 angiotensin receptor (AT1R) is the effector receptor for Ang II. These G protein-coupled receptors (GPCRs) are ubiquitously expressed in a variety of cell lineages and tissues relevant to cardiovascular disease throughout the body. The advent of cell specific deletion of genes using Cre LoxP technology in mice has allowed for the identification of discreet actions of AT1Rs in blood pressure control and kidney disease. The kidney is one of the major targets of the RAS, which is responsible in maintaining fluid, electrolyte balance, and blood pressure. In this review we will discuss the role of AT1Rs in the kidney, vasculature, and immune cells and address their effects on hypertension and kidney disease.
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MESH Headings
- Angiotensin I/genetics
- Angiotensin I/metabolism
- Angiotensin II/genetics
- Angiotensin II/metabolism
- Angiotensin-Converting Enzyme 2/genetics
- Angiotensin-Converting Enzyme 2/metabolism
- Animals
- Blood Pressure/genetics
- Gene Expression Regulation
- Humans
- Hypertension/genetics
- Hypertension/metabolism
- Hypertension/pathology
- Kidney Tubules, Proximal/enzymology
- Kidney Tubules, Proximal/pathology
- Mice
- Mice, Knockout
- Peptide Fragments/genetics
- Peptide Fragments/metabolism
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/genetics
- Receptor, Angiotensin, Type 2/metabolism
- Renal Insufficiency, Chronic/genetics
- Renal Insufficiency, Chronic/metabolism
- Renal Insufficiency, Chronic/pathology
- Renin-Angiotensin System/genetics
- Signal Transduction
- Water-Electrolyte Balance/genetics
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Affiliation(s)
- Fitra Rianto
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, United States
| | - Thien Hoang
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, United States
| | - Ritika Revoori
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, United States
| | - Matthew A Sparks
- Division of Nephrology, Department of Medicine, Duke University School of Medicine, Durham, NC, United States; Renal Section, Durham VA Health Care System, Durham, NC, United States.
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Mizuguchi K, Aoki H, Aoyama M, Kawaguchi Y, Waguri-Nagaya Y, Ohte N, Asai K. Three-dimensional spheroid culture induces apical-basal polarity and the original characteristics of immortalized human renal proximal tubule epithelial cells. Exp Cell Res 2021; 404:112630. [PMID: 33971195 DOI: 10.1016/j.yexcr.2021.112630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/21/2021] [Accepted: 04/27/2021] [Indexed: 10/21/2022]
Abstract
The proximal tubules, which are part of the kidney, maintain blood homeostasis by absorbing amino acids, glucose, water, and ions such as sodium (Na), potassium, and bicarbonate. Proximal tubule dysfunction is associated with the pathogenesis of many kidney diseases. Renal proximal tubular epithelial cells (RPTECs) are responsible for the main functions of the proximal tubules. Therefore, in vitro experiments using RPTECs would greatly enhance our understanding of nephron physiology and pathobiology. It is preferable to use immortalized cell lines, such as human kidney-2 (HK-2) cells, because they are derived from humans and maintain growth indefinitely. However, tissue-specific RPTEC phenotypes, including apical-basal polarization, are frequently lost in conventional two-dimensional culture methods in part due to microenvironmental deficiencies. To overcome this limitation, we developed a three-dimensional (3D) spheroid culture method for HK-2 cells using an extracellular matrix. HK-2 spheroids in 3D culture formed a tubule-like architecture with cellular polarity and showed markedly restored Na transport function. 3D culture of HK-2 cells also increased expression of kidney development-related genes, including WNT9B. Models of human renal tubules using HK-2 spheroids will greatly improve our understanding of the physiology and pathobiology of the kidney.
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Affiliation(s)
- Ken Mizuguchi
- Department of Glial Cell Biology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan; Department of Cardiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan.
| | - Hiromasa Aoki
- Department of Pathobiology, Nagoya City University Graduate School of Pharmaceutical Sciences, 3-1 Tanabe-dori, 25 Mizuho-ku, Nagoya, 467-8603, Japan
| | - Mineyoshi Aoyama
- Department of Pathobiology, Nagoya City University Graduate School of Pharmaceutical Sciences, 3-1 Tanabe-dori, 25 Mizuho-ku, Nagoya, 467-8603, Japan
| | - Yohei Kawaguchi
- Department of Glial Cell Biology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan; Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan
| | - Yuko Waguri-Nagaya
- Department of Orthopaedic Surgery, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan
| | - Nobuyuki Ohte
- Department of Cardiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan
| | - Kiyofumi Asai
- Department of Glial Cell Biology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan.
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88
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Kidney physiology and susceptibility to acute kidney injury: implications for renoprotection. Nat Rev Nephrol 2021; 17:335-349. [PMID: 33547418 DOI: 10.1038/s41581-021-00394-7] [Citation(s) in RCA: 132] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/05/2021] [Indexed: 01/30/2023]
Abstract
Kidney damage varies according to the primary insult. Different aetiologies of acute kidney injury (AKI), including kidney ischaemia, exposure to nephrotoxins, dehydration or sepsis, are associated with characteristic patterns of damage and changes in gene expression, which can provide insight into the mechanisms that lead to persistent structural and functional damage. Early morphological alterations are driven by a delicate balance between energy demand and oxygen supply, which varies considerably in different regions of the kidney. The functional heterogeneity of the various nephron segments is reflected in their use of different metabolic pathways. AKI is often linked to defects in kidney oxygen supply, and some nephron segments might not be able to shift to anaerobic metabolism under low oxygen conditions or might have remarkably low basal oxygen levels, which enhances their vulnerability to damage. Here, we discuss why specific kidney regions are at particular risk of injury and how this information might help to delineate novel routes for mitigating injury and avoiding permanent damage. We suggest that the physiological heterogeneity of the kidney should be taken into account when exploring novel renoprotective strategies, such as improvement of kidney tissue oxygenation, stimulation of hypoxia signalling pathways and modulation of cellular energy metabolism.
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89
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Feraille É, Olivier V. [Role of distal nephron in the control of extracellular volume in physiology and in nephrotic syndrome]. Med Sci (Paris) 2021; 37:359-365. [PMID: 33908853 DOI: 10.1051/medsci/2021032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The kidney plays a major role to maintain the constancy of the "milieu intérieur" by adjusting the urinary excretion of water and solutes to the requirement of the body balance. This function is coordinated with elimination of waste products generated among others by the catabolism of proteins and nucleic acids. To cope with these two major functions, the human kidneys generate each day about 180 L of ultrafiltrate from plasma and reabsorbs the vast majority of filtered water and solutes to excrete daily about one-two liter(s) of urine containing concentrations of sodium, potassium and chloride ranging from 20 to 200 mM. The final adjustment of urine composition is finely tuned along the aldosterone-sensitive distal nephron (ASDN) which includes the distal convoluted tubule and the collecting system (connecting tubule and collecting duct). Sodium reabsorption is predominant along the distal tubule if potassium must be spared, or along the collecting system when large amounts of potassium must be secreted. Nephrotic syndrome is characterized by heavy proteinuria consecutive to a glomerular injury, associated with renal sodium and water retention taking initially place along ASDN and leading to edema.
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Affiliation(s)
- Éric Feraille
- Département de physiologie cellulaire et métabolisme, Université de Genève, Centre médical universitaire, 1 rue Michel-Servet, CH-1211 Genève 4, Suisse
| | - Valérie Olivier
- Département de physiologie cellulaire et métabolisme, Université de Genève, Centre médical universitaire, 1 rue Michel-Servet, CH-1211 Genève 4, Suisse
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90
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Nakatsuka A, Yamaguchi S, Eguchi J, Kakuta S, Iwakura Y, Sugiyama H, Wada J. A Vaspin-HSPA1L complex protects proximal tubular cells from organelle stress in diabetic kidney disease. Commun Biol 2021; 4:373. [PMID: 33742129 PMCID: PMC7979793 DOI: 10.1038/s42003-021-01902-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 02/23/2021] [Indexed: 12/12/2022] Open
Abstract
Proximal tubular cells (PTCs) are crucial for maintaining renal homeostasis, and tubular injuries contribute to progression of diabetic kidney disease (DKD). However, the roles of visceral adipose tissue-derived serine protease inhibitor (vaspin) in the development of DKD is not known. We found vaspin maintains PTCs through ameliorating ER stress, autophagy impairment, and lysosome dysfunction in DKD. Vaspin-/- obese mice showed enlarged and leaky lysosomes in PTCs associated with increased apoptosis, and these abnormalities were also observed in the patients with DKD. During internalization into PTCs, vaspin formed a complex with heat shock protein family A (Hsp70) member 1 like (HSPA1L) as well as 78 kDa glucose-regulated protein (GRP78). Both vaspin-partners bind to clathrin heavy chain and involve in the endocytosis. Notably, albumin-overload enhanced extracellular release of HSPA1L and overexpression of HSPA1L dissolved organelle stresses, especially autophagy impairment. Thus, vapsin/HSPA1L-mediated pathways play critical roles in maintaining organellar function of PTCs in DKD.
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Affiliation(s)
- Atsuko Nakatsuka
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan.
- Division of Kidney, Diabetes and Endocrine Diseases, Okayama University Hospital, Kita-ku, Okayama, 700-8558, Japan.
| | - Satoshi Yamaguchi
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan
| | - Jun Eguchi
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan
| | - Shigeru Kakuta
- Department of Biomedical Science, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo, 113-8657, Japan
| | - Yoichiro Iwakura
- Research Institute for Biomedical Sciences, Tokyo University of Science, Chiba, 278-0022, Japan
| | - Hitoshi Sugiyama
- Department of Human Resource Development of Dialysis Therapy for Kidney Disease, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan
| | - Jun Wada
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Kita-ku, Okayama, 700-8558, Japan.
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91
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Modulation of Tubular pH by Acetazolamide in a Ca 2+ Transport Deficient Mice Facilitates Calcium Nephrolithiasis. Int J Mol Sci 2021; 22:ijms22063050. [PMID: 33802660 PMCID: PMC8002449 DOI: 10.3390/ijms22063050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 01/16/2023] Open
Abstract
Proximal tubular (PT) acidosis, which alkalinizes the urinary filtrate, together with Ca2+ supersaturation in PT can induce luminal calcium phosphate (CaP) crystal formation. While such CaP crystals are known to act as a nidus for CaP/calcium oxalate (CaOx) mixed stone formation, the regulation of PT luminal Ca2+ concentration ([Ca2+]) under elevated pH and/or high [Ca2+] conditions are unknown. Since we found that transient receptor potential canonical 3 (TRPC3) knockout (KO; -/-) mice could produce mild hypercalciuria with CaP urine crystals, we alkalinized the tubular pH in TRPC3-/- mice by oral acetazolamide (0.08%) to develop mixed urinary crystals akin to clinical signs of calcium nephrolithiasis (CaNL). Our ratiometric (λ340/380) intracellular [Ca2+] measurements reveal that such alkalization not only upsurges Ca2+ influx into PT cells, but the mode of Ca2+ entry switches from receptor-operated to store-operated pathway. Electrophysiological experiments show enhanced bicarbonate related current activity in treated PT cells which may determine the stone-forming phenotypes (CaP or CaP/CaOx). Moreover, such alkalization promotes reactive oxygen species generation, and upregulation of calcification, inflammation, fibrosis, and apoptosis in PT cells, which were exacerbated in absence of TRPC3. Altogether, the pH-induced alteration of the Ca2+ signaling signature in PT cells from TRPC3 ablated mice exacerbated the pathophysiology of mixed urinary stone formation, which may aid in uncovering the downstream mechanism of CaNL.
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92
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Leaf Extracts of Anchomanes difformis Ameliorated Kidney and Pancreatic Damage in Type 2 Diabetes. PLANTS 2021; 10:plants10020300. [PMID: 33562428 PMCID: PMC7914445 DOI: 10.3390/plants10020300] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/12/2021] [Accepted: 01/18/2021] [Indexed: 12/28/2022]
Abstract
Kidney disease in diabetes is one of the common microvascular complications of diabetes mellitus implicated in end-stage renal failure. This study explored the ability of Anchomanes difformis to ameliorate kidney and pancreatic damage in type 2 diabetes mellitus using male Wistar rats. Two weeks of fructose (10%) administration followed by streptozotocin (40 mg/kg) were used to induce type 2 diabetes. Leaf extract (aqueous) of Anchomanes difformis (200 mg and 400 mg/kgBW) was administered orally for six weeks. Body weights were monitored, urea and creatinine were measured. Interleukins (IL)-1β, IL-6, IL-10, IL-18, and TNFα were measured in the kidney lysate. CAT, SOD, ORAC, FRAP, and MDA levels were also evaluated in the kidney. Transcription factors (Nrf2 and NF-ĸB/p65) and apoptotic markers (Bcl2 and caspase 3) were investigated in the kidney. Histological sections of the pancreas and kidney tissues were examined for any visible pathology. Supplementation with Anchomanesdifformis enhanced antioxidant status, modulated inflammatory response, and reduced apoptosis in the kidney. It also restored the kidney and pancreatic histoarchitecture of the treated diabetic rats. The pathophysiology associated with diabetic nephropathy and pancreatic damage showcase the importance of exploring the use of antidiabetic, nephroprotective agents such as Anchomanes difformis to kidney damage in type 2 diabetes.
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93
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Abstract
Metabolic alkalosis is an increase in blood pH to >7.45 due to a primary increase in serum bicarbonate (HCO3 -). Metabolic alkalosis results from alkali accumulation or acid loss, and it is associated with a secondary increase in carbon dioxide arterial pressure (PaCO2). Metabolic alkalosis is a common acid-base disorder, especially in critically ill patients. The pathogenesis of chronic metabolic alkalosis includes two derangements, generation of metabolic alkalosis via gain of alkali or loss of acid and maintenance of metabolic alkalosis by increased tubular HCO3 - reabsorption (failure of the kidneys to excrete excess alkali). Metabolic alkalosis is the most common acid-base disorder in hospitalized patients, particularly in the surgical critical care unit. Mortality increases as pH increases.
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Affiliation(s)
- Mohammad Tinawi
- Nephrology, Nephrology Specialists, P.C, Munster, USA
- Medicine, Indiana University School of Medicine Northwest, Gary, USA
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94
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Aljaylani A, Fluitt M, Piselli A, Shepard BD, Tiwari S, Ecelbarger CM. Acid Loading Unmasks Glucose Homeostatic Instability in Proximal-Tubule-Targeted Insulin/Insulin-Like-Growth-Factor-1 Receptor Dual Knockout Mice. Cell Physiol Biochem 2021; 54:682-695. [PMID: 32678535 DOI: 10.33594/000000248] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2020] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND/AIMS Metabolic syndrome and type 2 diabetes are associated with some degree of acidosis. Acidosis has also been shown to upregulate renal gluconeogenesis. Whether impaired insulin or insulin-like-growth factor 1 receptor (IGF1) signaling alter this relationship is not known. Our aim was to determine the effects of deletion of insulin and IGF1 receptors (Insr and Igf1r) from renal proximal tubule (PT) on the gluconeogenic response to acidosis. METHODS We developed a mouse model with PT-targeted dual knockout (KO) of the Insr/Igf1r by driving Cre-recombinase with the gamma-glutamyl transferase (gGT) promoter. Male and female mice were maintained as control or acidotic by treatment with NH4Cl in the drinking water for 1-week. RESULTS Acidosis in both genotypes increased renal expression of phosphoenolpyruvate carboxykinase (PEPCK) and fructose-1-bisphosphatase (FBP1), but not glucose-6-phosphatase catalytic subunit (G6PC), which showed significantly lower expression in the KO regardless of treatment. Several differences between KO and WT suggested a protective role for insulin/IGF1 receptor signaling in maintaining relative euglycemia in the face of acidosis. First, the increase in FBP1 with acid was greater in the KO (significant interactive term). Secondly, proximal-tubule-associated FOXO1 and AKT overall protein levels were suppressed by acid loading in the KO, but not in the WT. Robust intact insulin signaling would be needed to reduce gluconeogenesis in PT. Third, phosphorylated FOXO1 (pS256) levels were markedly reduced by acid loading in the KO PT, but not in the WT. This reduction would support greater gluconeogenesis. Fourth, the sodium-glucose cotransporter (SGLT1) was increased by acid loading in the KO kidney, but not the WT. While this would not necessarily affect gluconeogenesis, it could result in increased circulatory glucose via renal reabsorption. Reduced susceptibility to glucose-homeostatic dysregulation in the WT could potentially relate to the sharp (over 50%) reduction in renal levels of sirtuin-1 (SIRT1), which deacetylates and regulates transcription of a number of genes. This reduction was absent in the KO. CONCLUSION Insulin resistance of the kidney may increase whole-body glucose instability a major risk factor for morbidity in diabetes. High dietary acid loads provide a dilemma for the kidney, as ammoniagenesis liberates α-ketoglutarate, which is a substrate for gluconeogenesis. We demonstrate an important role for insulin and/or IGF1 receptor signaling in the PT to facilitate this process and reduce excursions in blood glucose. Thus, medications and lifestyle changes that improve renal insulin sensitivity may also provide added benefit in type 2 diabetes especially when coupled with metabolic acidosis.
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Affiliation(s)
- Abdullah Aljaylani
- Division of Endocrinology and Metabolism, Department of Medicine, Georgetown University, Washington, D.C., USA
| | - Maurice Fluitt
- Division of Endocrinology and Metabolism, Department of Medicine, Georgetown University, Washington, D.C., USA
| | - Alexandra Piselli
- Division of Endocrinology and Metabolism, Department of Medicine, Georgetown University, Washington, D.C., USA
| | - Blythe D Shepard
- School of Nursing and Health Studies, Department of Human Science, Georgetown University, Washington, D.C., USA
| | - Swasti Tiwari
- Department of Molecular Medicine & Biotechnology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Utter Pradesh, India
| | - Carolyn M Ecelbarger
- Division of Endocrinology and Metabolism, Department of Medicine, Georgetown University, Washington, D.C., USA,
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95
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Siddiqui AM, Gawo GA, Maqbool K. On slip of a viscous fluid through proximal renal tubule with linear reabsorption. AIMS BIOPHYSICS 2021. [DOI: 10.3934/biophy.2021006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
<p>The hydrodynamical problem of flow in proximal renal tubule is investigated. Axisymmetric flow of viscous, incompressible fluid through the proximal renal tubule that undergoes linear reabsorption with slip at the wall is considered. The stream function is used to transform the governing equations to system of ordinary differential equations. The analytical solutions for velocity components, pressure distribution, fractional reabsorption and the shear stress are found. The effect of slip parameter and reabsorption rate on the flow have been investigated. The points of extreme values for the axial and radial velocity components are identified. The solution is applied to physiological data from human and rat kidney, and the results are presented in tables and graphs.</p>
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96
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Harris AN, Weiner ID. Sex differences in renal ammonia metabolism. Am J Physiol Renal Physiol 2021; 320:F55-F60. [PMID: 33308019 PMCID: PMC7847052 DOI: 10.1152/ajprenal.00531.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 12/09/2020] [Accepted: 12/10/2020] [Indexed: 01/27/2023] Open
Abstract
Sexual dimorphic variations are present in many aspects of biology and involve the structure and/or function of nearly every organ system. Acid-base homeostasis is critical for optimal health, and renal ammonia metabolism has a major role in the maintenance of acid-base homeostasis. Recent studies have shown sex-dependent differences in renal ammonia metabolism with regard to both basal ammonia excretion and the response to an exogenous acid load. These sexual dimorphisms are associated with structural changes in the proximal tubule and the collecting duct and variations in the expression of multiple proteins involved in ammonia metabolism and transport. Studies using orchiectomy-induced testosterone deficiency and physiological testosterone replacement have shown that testosterone underlies much of the sex-dependent differences in the proximal tubule. This parallels the finding that the canonical testosterone target receptor, androgen receptor (AR), is present exclusively in the proximal tubule. Thus testosterone, possibly acting through AR activation, regulates multiple components of renal structure and ammonia metabolism. The lack of detectable AR in the remainder of the nephron and collecting duct suggests that some dimorphisms in renal structure and ammonia transporter expression are mediated through mechanisms other than direct testosterone-dependent AR activation. A better understanding of the mechanism and biological implications of sex's effect on renal structure and ammonia metabolism is critical for optimizing our ability to care for both men and women with acid-base disturbances.
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Affiliation(s)
- Autumn N Harris
- Department of Small Animal Clinical Sciences, University of Florida College of Veterinary Medicine, Gainesville, Florida
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - I David Weiner
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
- Nephrology and Hypertension Section, Gainesville Veterans Administration Medical Center, Gainesville, Florida
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97
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Lemaire M. Novel Fanconi renotubular syndromes provide insights in proximal tubule pathophysiology. Am J Physiol Renal Physiol 2020; 320:F145-F160. [PMID: 33283647 DOI: 10.1152/ajprenal.00214.2020] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The various forms of Fanconi renotubular syndromes (FRTS) offer significant challenges for clinicians and present unique opportunities for scientists who study proximal tubule physiology. This review will describe the clinical characteristics, genetic underpinnings, and underlying pathophysiology of the major forms of FRST. Although the classic forms of FRTS will be presented (e.g., Dent disease or Lowe syndrome), particular attention will be paid to five of the most recently discovered FRTS subtypes caused by mutations in the genes encoding for L-arginine:glycine amidinotransferase (GATM), solute carrier family 34 (type Ii sodium/phosphate cotransporter), member 1 (SLC34A1), enoyl-CoAhydratase/3-hydroxyacyl CoA dehydrogenase (EHHADH), hepatocyte nuclear factor 4A (HNF4A), or NADH dehydrogenase complex I, assembly factor 6 (NDUFAF6). We will explore how mutations in these genes revealed unexpected mechanisms that led to compromised proximal tubule functions. We will also describe the inherent challenges associated with gene discovery studies based on findings derived from small, single-family studies by focusing the story of FRTS type 2 (SLC34A1). Finally, we will explain how extensive alternative splicing of HNF4A has resulted in confusion with mutation nomenclature for FRTS type 4.
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Affiliation(s)
- Mathieu Lemaire
- Division of Nephrology and Cell Biology Program, SickKids Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Pediatrics, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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98
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Legouis D, Faivre A, Cippà PE, de Seigneux S. Renal gluconeogenesis: an underestimated role of the kidney in systemic glucose metabolism. Nephrol Dial Transplant 2020; 37:1417-1425. [PMID: 33247734 DOI: 10.1093/ndt/gfaa302] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Indexed: 12/21/2022] Open
Abstract
Glucose levels are tightly regulated at all times. Gluconeogenesis is the metabolic pathway dedicated to glucose synthesis from non-hexose precursors. Gluconeogenesis is critical for glucose homoeostasis, particularly during fasting or stress conditions. The renal contribution to systemic gluconeogenesis is increasingly recognized. During the post-absorptive phase, the kidney accounts for ∼40% of endogenous gluconeogenesis, occurring mainly in the kidney proximal tubule. The main substrate for renal gluconeogenesis is lactate and the process is regulated by insulin and cellular glucose levels, but also by acidosis and stress hormones. The kidney thus plays an important role in the maintenance of glucose and lactate homoeostasis during stress conditions. The impact of acute and chronic kidney disease and proximal tubular injury on gluconeogenesis is not well studied. Recent evidence shows that in both experimental and clinical acute kidney injury, impaired renal gluconeogenesis could significantly participate in systemic metabolic disturbance and thus alter the prognosis. This review summarizes the biochemistry of gluconeogenesis, the current knowledge of kidney gluconeogenesis, its modifications in kidney disease and the clinical relevance of this fundamental biological process in human biology.
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Affiliation(s)
- David Legouis
- Department of Acute Medicine, Division of Intensive Care, University Hospitals of Geneva, Geneva, Switzerland.,Department of Medicine, Laboratory of Nephrology, University Hospitals of Geneva, Geneva, Switzerland.,Department of Cell Physiology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Anna Faivre
- Department of Medicine, Laboratory of Nephrology, University Hospitals of Geneva, Geneva, Switzerland.,Department of Cell Physiology, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Pietro E Cippà
- Division of Nephrology, Ente Ospedaliero Cantonale, Lugano, Switzerland
| | - Sophie de Seigneux
- Department of Medicine, Laboratory of Nephrology, University Hospitals of Geneva, Geneva, Switzerland.,Department of Cell Physiology, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Department of Medicine, Division of Nephrology, University Hospitals of Geneva, Geneva, Switzerland
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99
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Edwards A, Christensen EI, Unwin RJ, Norden AGW. Predicting the protein composition of human urine in normal and pathological states: Quantitative description based on Dent1 disease (
CLCN5
mutation). J Physiol 2020; 599:323-341. [DOI: 10.1113/jp280740] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 10/16/2020] [Indexed: 01/25/2023] Open
Affiliation(s)
- Aurélie Edwards
- Department of Biomedical Engineering Boston University Boston MA USA
| | | | - Robert J. Unwin
- Department of Renal Medicine Royal Free Campus University College London London UK
| | - Anthony G. W. Norden
- Department of Renal Medicine Royal Free Campus University College London London UK
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100
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Molecular Mechanisms of SGLT2 Inhibitor on Cardiorenal Protection. Int J Mol Sci 2020; 21:ijms21217833. [PMID: 33105763 PMCID: PMC7660105 DOI: 10.3390/ijms21217833] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/20/2020] [Accepted: 10/20/2020] [Indexed: 12/14/2022] Open
Abstract
The development of sodium-glucose transporter 2 inhibitor (SGLT2i) broadens the therapeutic strategies in treating diabetes mellitus. By inhibiting sodium and glucose reabsorption from the proximal tubules, the improvement in insulin resistance and natriuresis improved the cardiovascular mortality in diabetes mellitus (DM) patients. It has been known that SGLT2i also provided renoprotection by lowering the intraglomerular hypertension by modulating the pre- and post- glomerular vascular tone. The application of SGLT2i also provided metabolic and hemodynamic benefits in molecular aspects. The recent DAPA-CKD trial and EMPEROR-Reduced trial provided clinical evidence of renal and cardiac protection, even in non-DM patients. Therefore, the aim of the review is to clarify the hemodynamic and metabolic modulation of SGLT2i from the molecular mechanism.
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