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Tang P, Geddes RF, Chang Y, Jepson RE, van den Broek DHN, Lötter N, Elliott J. Risk factors and implications associated with ultrasound-diagnosed nephrocalcinosis in cats with chronic kidney disease. J Vet Intern Med 2024; 38:1563-1576. [PMID: 38438128 PMCID: PMC11099775 DOI: 10.1111/jvim.17034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 02/16/2024] [Indexed: 03/06/2024] Open
Abstract
BACKGROUND Microscopic nephrocalcinosis is a common pathological feature of chronic kidney disease (CKD) in cats. Detection of macroscopic nephrocalcinosis using ultrasonography and its implications remain unexplored. OBJECTIVES Identify risk factors associated with ultrasound-diagnosed nephrocalcinosis and evaluate the influence of nephrocalcinosis on CKD progression. ANIMALS Thirty-six euthyroid client-owned cats with CKD. METHODS Prospective cohort study. Cats with CKD with and without ionized hypercalcemia were enrolled for renal ultrasonography. Cats were categorized according to the presence or absence of ultrasound-diagnosed nephrocalcinosis. Binary logistic regression was performed to identify nephrocalcinosis risk factors. The influence of nephrocalcinosis on CKD progression was assessed using linear mixed models. RESULTS Ultrasound-diagnosed nephrocalcinosis was evident in 61% of CKD cats overall, with increased prevalence (81%) in those with hypercalcemia. At enrollment, higher blood ionized calcium concentration (odds ratio [OR], 1.27 per 0.1 mg/dL; P = .01), plasma phosphate concentration (OR, 1.16 per 0.1 mg/dL; P = .05), plasma creatinine concentration (OR, 1.29 per 0.1 mg/dL; P = .02) and alanine aminotransferase activity (OR, 2.08 per 10 U/L; P = .04) were independent nephrocalcinosis risk factors. The rate of change in log-transformed fibroblast growth factor-23 differed significantly between groups (P = .04). Cats with CKD and nephrocalcinosis had increasing plasma creatinine concentrations (.03 ± .01 mg/dL/month; P = .04) and phosphate concentrations (.06 ± .02 mg/dL/month; P < .001) and decreasing body weight (.02 ± .01 kg/month; P < .001) over time. CONCLUSIONS AND CLINICAL IMPORTANCE Nephrocalcinosis is prevalent in cats with CKD, especially in those with hypercalcemia. This pathological feature appears to be associated with CKD progression in cats.
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Affiliation(s)
- Pak‐Kan Tang
- Department of Comparative Biomedical Sciences, Royal Veterinary CollegeUniversity of LondonLondonUK
| | - Rebecca F. Geddes
- Department of Clinical Science and Services, Royal Veterinary CollegeUniversity of LondonLondonUK
| | - Yu‐Mei Chang
- Research Support Office, Royal Veterinary CollegeUniversity of LondonLondonUK
| | - Rosanne E. Jepson
- Department of Clinical Science and Services, Royal Veterinary CollegeUniversity of LondonLondonUK
| | | | - Nicola Lötter
- Department of Comparative Biomedical Sciences, Royal Veterinary CollegeUniversity of LondonLondonUK
| | - Jonathan Elliott
- Department of Comparative Biomedical Sciences, Royal Veterinary CollegeUniversity of LondonLondonUK
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Tang P, Geddes RF, Chang Y, Jepson RE, van den Broek DHN, Lötter N, Elliott J. Detection of nephrocalcinosis using ultrasonography, micro-computed tomography, and histopathology in cats. J Vet Intern Med 2024; 38:1553-1562. [PMID: 38348812 PMCID: PMC11099790 DOI: 10.1111/jvim.17011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 01/26/2024] [Indexed: 05/18/2024] Open
Abstract
BACKGROUND Identification of nephrocalcinosis in cats with chronic kidney disease (CKD) is of clinical interest but the ability of ultrasonography to detect nephrocalcinosis is uncertain. OBJECTIVES To compare ultrasonography, micro-computed tomography (μCT) and histopathology for identification of nephrocalcinosis. ANIMALS Twelve kidneys from 7 euthyroid client-owned cats with CKD. METHODS Descriptive study. Renal ultrasonography was performed ante-mortem for nephrocalcinosis detection. Kidneys were grouped based on nephrocalcinosis: present, suspected, or absent. When cats died, necropsy was performed. Renal tissue was evaluated using μCT for macroscopic nephrocalcinosis, and nephrocalcinosis volume-to-kidney tissue ratio (macro-VN:KT) and sagittal nephrocalcinosis area-to-kidney tissue ratio (macro-AN:KT) were calculated. Each kidney subsequently was bisected longitudinally, formalin-fixed, and paraffin-embedded for microscopic nephrocalcinosis assessment using von Kossa and Alizarin red staining with AN:KT (VK-micro-AN:KT and AR-micro-AN:KT) quantified using ImageJ. Data are presented as median (range). Relationships between macroscopic and microscopic AN:KT were assessed using Spearman's correlation. RESULTS Nephrocalcinosis by ultrasonography was considered to be absent in 3, suspected in 3, and present in 5 kidneys; 1 kidney had nephrolithiasis with nephrocalcinosis. The macro-VN:KT was 0.001%, 0.001%, and 0.019%, and the macro-AN:KT was 0.08%, 0.30%, and 1.47%, respectively. Histologically, VK-micro-AN:KT was 0.21%, 2.85%, and 4.56%, and AR-micro-AN:KT was 1.73%, 5.82%, and 8.90% for kidneys where ultrasonographic macro-nephrocalcinosis was absent, suspected, or present, respectively. A strong correlation was identified between macroscopic (macro-AN:KT) and microscopic (VK-micro-AN:KT) nephrocalcinosis (rs = 0.76; P = .01). CONCLUSIONS AND CLINICAL IMPORTANCE Ultrasonographically diagnosed nephrocalcinosis correlates well with macroscopic and microscopic nephrocalcinosis at necropsy despite their separation in time.
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Affiliation(s)
- Pak‐Kan Tang
- Department of Comparative Biomedical Sciences, Royal Veterinary CollegeUniversity of LondonLondonUnited Kingdom
| | - Rebecca F. Geddes
- Department of Clinical Science and Services, Royal Veterinary CollegeUniversity of LondonLondonUnited Kingdom
| | - Yu‐Mei Chang
- Research Support Office, Royal Veterinary CollegeUniversity of LondonLondonUnited Kingdom
| | - Rosanne E. Jepson
- Department of Clinical Science and Services, Royal Veterinary CollegeUniversity of LondonLondonUnited Kingdom
| | | | - Nicola Lötter
- Department of Comparative Biomedical Sciences, Royal Veterinary CollegeUniversity of LondonLondonUnited Kingdom
| | - Jonathan Elliott
- Department of Comparative Biomedical Sciences, Royal Veterinary CollegeUniversity of LondonLondonUnited Kingdom
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Wang X, Yu X, Gavardinas K, Dey A, Zhang HY, Porter G, Porras L, Yu L, Guo H, Reidy CA, Haas JV, Xu Y, Kowala MC, Jadhav PK, Wetterau JR. Effect of an NHE3 inhibitor in combination with an NPT2b inhibitor on gastrointestinal phosphate absorption in Rodent models. PLoS One 2024; 19:e0292091. [PMID: 38277356 PMCID: PMC10817170 DOI: 10.1371/journal.pone.0292091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 09/12/2023] [Indexed: 01/28/2024] Open
Abstract
Many of the pathological consequences of chronic kidney disease can be attributed to an elevation in serum phosphate levels. Current therapies focused on decreasing intestinal phosphate absorption to treat hyperphosphatemia are inadequate. The most effective therapeutic strategy may be to target multiple absorptive pathways. In this study, the ability of a novel inhibitor of the intestinal sodium hydrogen exchanger 3 (NHE3), LY3304000, which inhibits paracellular, diffusional uptake of phosphate, to work in combination with an inhibitor of the active transporter, sodium dependent phosphate cotransporter 2b (NPT2b), LY3358966, was explored. LY3304000 modestly inhibited the acute uptake of phosphate into plasma of rats, while surprisingly, it doubled the rate of phosphate uptake in mice, an animal model dominated by NPT2b mediated acute phosphate uptake. In rats, LY3004000 and LY3358966 work in concert to inhibit acute phosphate uptake. On top of LY3358966, LY3304000 further decreased the acute uptake of phosphate into plasma. Studies measuring the recovery of radiolabeled phosphate in the intestine demonstrated LY3304000 and LY3358966 synergistically inhibited the absorption of phosphate in rats. We hypothesize the synergism is because the NHE3 inhibitor, LY3304000, has two opposing effects on intestinal phosphate absorption in rats, first it decreases diffusion mediated paracellular phosphate absorption, while second, it simultaneously increases phosphate absorption through the NPT2b pathway. NHE3 inhibition decreases proton export from enterocytes and raises the cell surface pH. In vitro, NPT2b mediated phosphate transport is increased at higher pHs. The increased NPT2b mediated transport induced by NHE3 inhibition is masked in rats which have relatively low levels of NPT2b mediated phosphate transport, by the more robust inhibition of diffusion mediated phosphate absorption. Thus, the inhibition of NPT2b mediated phosphate transport in rats in the presence of NHE3 inhibition has an effect that exceeds its effect in the absence of NHE3 inhibition, leading to the observed synergism on phosphate absorption between NPT2b and NHE3 inhibition.
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Affiliation(s)
- Xiaojun Wang
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Xiaohong Yu
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Kostas Gavardinas
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Asim Dey
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Hong Y. Zhang
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Gina Porter
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Leah Porras
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Lan Yu
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Haihong Guo
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Charles A. Reidy
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Joseph V. Haas
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Yanping Xu
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Mark C. Kowala
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Prabhakar K. Jadhav
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - John R. Wetterau
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
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Wagner CA, Unwin R, Lopez-Garcia SC, Kleta R, Bockenhauer D, Walsh S. The pathophysiology of distal renal tubular acidosis. Nat Rev Nephrol 2023; 19:384-400. [PMID: 37016093 DOI: 10.1038/s41581-023-00699-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2023] [Indexed: 04/06/2023]
Abstract
The kidneys have a central role in the control of acid-base homeostasis owing to bicarbonate reabsorption and production of ammonia and ammonium in the proximal tubule and active acid secretion along the collecting duct. Impaired acid excretion by the collecting duct system causes distal renal tubular acidosis (dRTA), which is characterized by the failure to acidify urine below pH 5.5. This defect originates from reduced function of acid-secretory type A intercalated cells. Inherited forms of dRTA are caused by variants in SLC4A1, ATP6V1B1, ATP6V0A4, FOXI1, WDR72 and probably in other genes that are yet to be discovered. Inheritance of dRTA follows autosomal-dominant and -recessive patterns. Acquired forms of dRTA are caused by various types of autoimmune diseases or adverse effects of some drugs. Incomplete dRTA is frequently found in patients with and without kidney stone disease. These patients fail to appropriately acidify their urine when challenged, suggesting that incomplete dRTA may represent an intermediate state in the spectrum of the ability to excrete acids. Unrecognized or insufficiently treated dRTA can cause rickets and failure to thrive in children, osteomalacia in adults, nephrolithiasis and nephrocalcinosis. Electrolyte disorders are also often present and poorly controlled dRTA can increase the risk of developing chronic kidney disease.
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Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK.
| | - Robert Unwin
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
| | - Sergio C Lopez-Garcia
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
- Department of Paediatric Nephrology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Robert Kleta
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
| | - Detlef Bockenhauer
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
- Department of Paediatric Nephrology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Stephen Walsh
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
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Serum and Urinary Soluble α-Klotho as Markers of Kidney and Vascular Impairment. Nutrients 2023; 15:nu15061470. [PMID: 36986200 PMCID: PMC10057552 DOI: 10.3390/nu15061470] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/12/2023] [Accepted: 03/16/2023] [Indexed: 03/22/2023] Open
Abstract
This study was designed to investigate the controversy on the potential role of sKlotho as an early biomarker in Chronic Kidney Disease–Mineral Bone Disorder (CKD-MBD), to assess whether sKlotho is a reliable marker of kidney α-Klotho, to deepen the effects of sKlotho on vascular smooth muscle cells (VSMCs) osteogenic differentiation and to evaluate the role of autophagy in this process. Experimental studies were conducted in CKD mice fed a normal phosphorus (CKD+NP) or high phosphorus (CKD+HP) diet for 14 weeks. The patients’ study was performed in CKD stages 2–5 and in vitro studies which used VSMCs exposed to non-calcifying medium or calcifying medium with or without sKlotho. The CKD experimental model showed that the CKD+HP group reached the highest serum PTH, P and FGF23 levels, but the lowest serum and urinary sKlotho levels. In addition, a positive correlation between serum sKlotho and kidney α-Klotho was found. CKD mice showed aortic osteogenic differentiation, together with increased autophagy. The human CKD study showed that the decline in serum sKlotho is previous to the rise in FGF23. In addition, both serum sKlotho and FGF23 levels correlated with kidney function. Finally, in VSMCs, the addition of sKlotho prevented osteogenic differentiation and induced autophagy. It can be concluded that serum sKlotho was the earliest CKD-MBD biomarker, a reliable indicator of kidney α-Klotho and that might protect against osteogenic differentiation by increasing autophagy. Nevertheless, further studies are needed to investigate the mechanisms of this possible protective effect.
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Colussi G, Menegotto A, Querques M, Ravera F, Verdesca S, Colombo V, Minetti EE. End-proximal tubule phosphate concentration increases as GFR falls in humans: measurement by means of a lithium clearance-based methodology. Nephrol Dial Transplant 2023; 38:671-678. [PMID: 35561727 DOI: 10.1093/ndt/gfac179] [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: 01/27/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Microscopic nephrocalcinosis secondary to intratubular calcium phosphate (CaP) precipitation is thought to accelerate progression to end-stage renal failure in chronic kidney diseases. In phosphorus (P)-loaded uninephrectomized rats, intratubular CaP crystal formation and progressive tubular damage occurred when end-proximal tubule P concentration (ePTpc) increased above a threshold level. METHODS We have calculated ePTpc in humans by urine P and creatinine concentration, with the end-proximal tubule fluid volume calculated either as lithium (Li) clearance (ePTpc-Li) or as a fixed 0.7 fraction of glomerular filtration rate (GFR), as published (ePTpc-70). Healthy people undergoing living transplant kidney donation before (DON-pre, n = 70) and after (DON-post, n = 64) nephrectomy and 25 patients with stage 2-5 CKD were investigated while on regular free diet. RESULTS ePTpc showed a stepwise increase with decreasing functional renal mass (DON-pre 2.51 ± 0.99 and 1.56 ± 0.47 mg/dL for ePTpc-Li and -70 calculation, respectively; DON-post 3.43 ± 1.14 and 2.18 ± 0.44; CKD 5.68 ± 3.30 and 3.00 ± 1.30, P < .001 for all); ePTpc was inversely correlated with Ccr and directly with PTH, fractional P excretion and excretion (UpV) corrected for GFR (P < .001 for all), but not with Pp. ePTpc-Li and ePTpc-70 were significantly correlated (r = 0.62, P < .001), but ePTpc-70 was lower than the corresponding ePTpc-Li. Levels of ePTpc increased above a suggested dangerous threshold when daily UpV/GFR was higher than about 10 mg/mLCcr. CONCLUSIONS ePTpc progressively increases in humans as functional renal mass falls independently from plasma P levels. Main determinants of ePTpc rise are GFR fall, degree of phosphaturia per unit GFR and P intake corrected for GFR. It may become a novel, potentially useful, indicator to guide management of CKD patients.
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Affiliation(s)
- Giacomo Colussi
- Division of Nephrology, Dialysis and Renal Transplantation, ASST-GOM Niguarda, Milan, Italy.,Ambrosiana Clinic-Sacra Famiglia Foundation, Milan, Italy
| | - Alberto Menegotto
- Division of Nephrology, Dialysis and Renal Transplantation, ASST-GOM Niguarda, Milan, Italy
| | - Marialuisa Querques
- Division of Nephrology, Dialysis and Renal Transplantation, ASST-GOM Niguarda, Milan, Italy
| | - Federica Ravera
- Division of Nephrology, Dialysis and Renal Transplantation, ASST-GOM Niguarda, Milan, Italy
| | - Simona Verdesca
- Division of Nephrology, Dialysis and Renal Transplantation, ASST-GOM Niguarda, Milan, Italy
| | - Valeriana Colombo
- Division of Nephrology, Dialysis and Renal Transplantation, ASST-GOM Niguarda, Milan, Italy
| | - Enrico E Minetti
- Division of Nephrology, Dialysis and Renal Transplantation, ASST-GOM Niguarda, Milan, Italy
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7
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Tang PK, Jepson RE, Chang YM, Geddes RF, Hopkinson M, Elliott J. Risk factors and implications associated with renal mineralization in chronic kidney disease in cats. J Vet Intern Med 2022; 36:634-646. [PMID: 35043997 PMCID: PMC8965253 DOI: 10.1111/jvim.16363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 01/07/2022] [Accepted: 01/07/2022] [Indexed: 11/28/2022] Open
Abstract
Background Nephrocalcinosis is a pathological feature of chronic kidney disease (CKD). Its pathophysiological implications for cats with CKD are unexplored. Objectives Identify nephrocalcinosis risk factors and evaluate its influence on CKD progression and all‐cause mortality. Animals Fifty‐one euthyroid client‐owned cats with International Renal Interest Society (IRIS) stages 2‐3 azotemic CKD. Methods Retrospective cohort study. Histopathological kidney sections were assessed for nephrocalcinosis (von Kossa stain). Nephrocalcinosis severity was determined by image analysis (ImageJ). Ordinal logistic regressions were performed to identify nephrocalcinosis risk factors. The influence of nephrocalcinosis on CKD progression and mortality risk were assessed using linear mixed model and Cox regression, respectively. Cats were categorized by their owner‐reported time‐averaged phosphate‐restricted diet (PRD) intake, where PRD comprised ≥50%, 10‐50%, or none of food intake. Results Nephrocalcinosis was rated as mild‐to‐severe in 78.4% and absent‐to‐minimal in 21.6% of cases. Higher baseline plasma total calcium concentration (tCa; odds ratio [OR] = 3.07 per 1 mg/dL; P = .02) and eating a PRD (10%‐50%: OR = 8.35; P = .01; ≥50%: OR = 5.47; P = .01) were independent nephrocalcinosis risk factors. Cats with absent‐to‐minimal nephrocalcinosis had increasing plasma creatinine (0.250 ± 0.074 mg/dL/month; P = .002), urea (5.06 ± 1.82 mg/dL/month; P = .01), and phosphate (0.233 ± 0.115 mg/dL/month; P = .05) concentrations over a 1‐year period, and had shorter median survival times than cats with mild‐to‐severe nephrocalcinosis. Conclusion and Clinical Importance Higher plasma tCa at CKD diagnosis and PRD intake are independently associated with nephrocalcinosis. However, nephrocalcinosis is not associated with rapid CKD progression in cats.
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Affiliation(s)
- Pak-Kan Tang
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, United Kingdom
| | - Rosanne E Jepson
- Department of Clinical Science and Services, Royal Veterinary College, University of London, London, United Kingdom
| | - Yu-Mei Chang
- Research Support Office, Royal Veterinary College, University of London, London, United Kingdom
| | - Rebecca F Geddes
- Department of Clinical Science and Services, Royal Veterinary College, University of London, London, United Kingdom
| | - Mark Hopkinson
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, United Kingdom
| | - Jonathan Elliott
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, United Kingdom
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Tang PK, Geddes RF, Jepson RE, Elliott J. A feline-focused review of chronic kidney disease-mineral and bone disorders - Part 2: Pathophysiology of calcium disorder and extraosseous calcification. Vet J 2021; 275:105718. [PMID: 34329743 DOI: 10.1016/j.tvjl.2021.105718] [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: 10/07/2020] [Revised: 06/23/2021] [Accepted: 07/21/2021] [Indexed: 10/20/2022]
Abstract
Derangements in mineral metabolism are one of the main entities in chronic kidney disease-mineral and bone disorder (CKD-MBD). This is the second of a two-part review of the physiology and pathophysiology of calcium homeostasis in feline CKD-MBD. While dysregulation in calcium homeostasis is known to contribute to the development of vascular calcification in CKD, evidence characterising the relationship between serum calcium concentration and nephrocalcinosis and nephrolithiasis is limited. Recently, fibroblast growth factor 23 (FGF23) and α-Klotho have gained increased research interest and been shown to be important biomarkers for the prediction of CKD progression in human patients. However, conflicting evidence exists on their role in calcium homeostasis and vascular and soft tissue calcification. This review details the pathophysiology of calcium disorders associated with CKD-MBD and its implications on vascular and soft tissue mineralisation in human and feline patients. Further prospective studies investigating the clinical consequences of calcium disturbances in cats with CKD are warranted and this may provide additional insight into the pathophysiology of feline CKD-MBD.
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Affiliation(s)
- Pak-Kan Tang
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, United Kingdom.
| | - Rebecca F Geddes
- Department of Clinical Science and Services, Royal Veterinary College, University of London, London, United Kingdom
| | - Rosanne E Jepson
- Department of Clinical Science and Services, Royal Veterinary College, University of London, London, United Kingdom
| | - Jonathan Elliott
- Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, United Kingdom
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9
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David K, Khalil R, Hannon H, Evenepoel P, Decallonne B. Therapy-Resistant Hypercalcemia in a Patient with Inactivating CYP24A1 Mutation and Recurrent Nephrolithiasis: Beware of Concomitant Hyperparathyroidism. Calcif Tissue Int 2020; 107:524-528. [PMID: 32743688 DOI: 10.1007/s00223-020-00738-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 07/23/2020] [Indexed: 12/30/2022]
Abstract
We describe a case harboring a homozygous CYP24A1 mutation with mild loss of function, first presenting with recurrent nephrolithiasis from the age of 22 onward, initially associated with hypercalcemia and low PTH concentrations. Over the years, hyperparathyroidism developed, resulting in more severe hypercalcemia. Also, kidney function deteriorated, most probably as a consequence of biopsy-proven nephrocalcinosis. Conventional treatment options for CYP24A1 mutation were not effective and/or tolerated (avoidance of sun exposure, diet, pamidronate, itraconazole). A total parathyroidectomy was performed resulting in a normocalcemic hypoparathyroidism without need for treatment with vitamin D analogs, a positive bone mineral balance and an improved kidney function.
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Affiliation(s)
- K David
- Department of Chronic Diseases and Metabolism, Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Herestraat 49, ON1 box 902, 3000, Leuven, Belgium.
- Department of Endocrinology, University Hospitals Leuven, Leuven, Belgium.
| | - R Khalil
- Department of Chronic Diseases and Metabolism, Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Herestraat 49, ON1 box 902, 3000, Leuven, Belgium
- Department of Endocrinology, University Hospitals Leuven, Leuven, Belgium
| | - H Hannon
- Department of Nephrology, Maria Middelares Hospital Ghent, Ghent, Belgium
| | - P Evenepoel
- Department of Immunology and Microbiology, Laboratory of Nephrology, KU Leuven, Leuven, Belgium
- Department of Nephrology and Renal Transplantation, University Hospitals Leuven, Leuven, Belgium
| | - B Decallonne
- Department of Chronic Diseases and Metabolism, Laboratory of Clinical and Experimental Endocrinology, KU Leuven, Herestraat 49, ON1 box 902, 3000, Leuven, Belgium
- Department of Endocrinology, University Hospitals Leuven, Leuven, Belgium
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10
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Smeraldi C, Giarola A, Aggett PJ, Moldeus P, Gundert-Remy U. Use of mechanistic information to derive chemical-specific adjustment factors - Refinement of risk assessment. Regul Toxicol Pharmacol 2020; 117:104776. [PMID: 32871170 DOI: 10.1016/j.yrtph.2020.104776] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/06/2020] [Accepted: 08/27/2020] [Indexed: 11/17/2022]
Abstract
When extrapolating data from animal toxicological studies a default factor (dUF) of 100 is applied to derive a heath based guidance value. The UF takes into account the interspecies differences (ID) and the intraspecies variability (IV). When re-evaluating the safety of phosphates used as food additives nephrocalcinosis was identified as the critical endpoint. The underlying mechanism for nephrocalcinosis was attributed to the precipitation of calcium phosphate in the kidney, depending on its solubility, irrespective of the species and the population. Based on the mechanism, the volume of primary urine, for which the glomerular filtration rate (GFR) was used as a proxy, was considered to be the only parameter relevant for ID and IV. Median value of GFR in rats was 4.0 ml/min/kg bw. In humans it was 1.6 ml/min/kg bw in healthy adults and 0.9 in elderly. These values were calculated from the distribution of the GFR data from 8 studies in rats (n = 191), 16 studies in adults (n = 1540) and 5 studies in elderly (n = 2608). Multiplying the distribution of the ratio rat/healthy humans (ID) with the distribution of the ratio healthy humans/elderly human (IV) resulted in a phosphate specific factor of 4.5 (3.3-6.7) (median; 25th - 75th percentile).
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Affiliation(s)
- C Smeraldi
- European Food Safety Authority, FIP Unit, Parma, Italy
| | - A Giarola
- European Food Safety Authority, FIP Unit, Parma, Italy
| | - P J Aggett
- Emeritus Professor of Child Health and Nutrition, University of Central Lancashire, Preston, UK
| | - P Moldeus
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - U Gundert-Remy
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Clinical Pharmacology and Toxicology, Berlin, Germany.
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11
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Miyata KN, Nast CC, Dai T, Dukkipati R, LaPage JA, Troost JP, Schurgers LJ, Kretzler M, Adler SG. Renal matrix Gla protein expression increases progressively with CKD and predicts renal outcome. Exp Mol Pathol 2018; 105:120-129. [PMID: 29981754 PMCID: PMC6167754 DOI: 10.1016/j.yexmp.2018.07.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 06/23/2018] [Accepted: 07/04/2018] [Indexed: 01/02/2023]
Abstract
BACKGROUND Matrix Gla Protein (MGP) is a potent inhibitor of ectopic calcification and modulates bone morphogenesis. Little is known about MGP expression or function in kidney. METHODS We investigated renal MGP expression in Sprague-Dawley rats after 5/6 nephrectomy (5/6 Nx) and in human kidney biopsies in the Nephrotic Syndrome Study Network (NEPTUNE) cohort. We analyzed associations between glomerular (n = 182) and tubulointerstitial (TI) (n = 219) MGP mRNA levels and the disease activity/histologic features in NEPTUNE patients. Additionally, uncarboxylated and carboxylated MGP (ucMGP and cMGP, respectively) were localized by immunohistochemistry and quantitated in kidney tissues of patients at different stages of CKD (n = 18). RESULTS Renal MGP expression was increased in rats after 5/6 Nx. In NEPTUNE data, baseline estimated glomerular filtration rate (eGFR) negatively correlated with glomerular and TI MGP expression (p <0.001). TI MGP expression strongly correlated with interstitial fibrosis, tubular atrophy, acute tubular injury, and interstitial inflammation, independent of eGFR. Kaplan-Meier analysis and multivariable Cox regression showed that higher levels of TI MGP expression were associated with an increased risk for the composite of 40% decline in eGFR and end-stage renal disease (ESRD) (HR, 3.31; 95% CI, 1.31 to 6.32; p =0.02). Glomerular and tubulointerstitial cells demonstrated nuclear and cytoplasmic cMGP and ucMGP staining, and eGFR inversely correlated with quantified glomerular cMGP staining (p <0.05). CONCLUSIONS Our data demonstrate that renal MGP expression is increased in human and experimental CKD, and is associated with renal outcome. Additional studies are needed to determine its mechanism of action.
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Affiliation(s)
- Kana N Miyata
- Division of Nephrology and Hypertension, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, 1124 W. Carson Street, Torrance, CA 90502, USA.
| | - Cynthia C Nast
- Department of Pathology, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los Angeles, CA 90048, USA
| | - Tiane Dai
- Division of Nephrology and Hypertension, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, 1124 W. Carson Street, Torrance, CA 90502, USA
| | - Ramanath Dukkipati
- Division of Nephrology and Hypertension, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, 1124 W. Carson Street, Torrance, CA 90502, USA
| | - Janine A LaPage
- Division of Nephrology and Hypertension, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, 1124 W. Carson Street, Torrance, CA 90502, USA
| | - Jonathan P Troost
- Division of Nephrology, Department of Pediatrics & Communicable Diseases, C.S. Mott Children's Hospital, University of Michigan, 1540 E Hospital Dr SPC 4259, Ann Arbor, MI 48109, USA
| | - Leon J Schurgers
- Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, PO Box 616, 6200, MD, Maastricht, the Netherlands
| | - Matthias Kretzler
- Division of Nephrology, Department of Internal Medicine, University of Michigan, 1560 MSRB II, 1150 West Medical Center Drive, SPC5676, Ann Arbor, MI 48109, USA
| | - Sharon G Adler
- Division of Nephrology and Hypertension, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, 1124 W. Carson Street, Torrance, CA 90502, USA
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12
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Wei FF, Thijs L, Zhang ZY, Jacobs L, Yang WY, Salvi E, Citterio L, Cauwenberghs N, Kuznetsova T, E A Drummen N, Hara A, Manunta P, Li Y, Verhamme P, Allegaert K, Cusi D, Vermeer C, Staessen JA. The risk of nephrolithiasis is causally related to inactive matrix Gla protein, a marker of vitamin K status: a Mendelian randomization study in a Flemish population. Nephrol Dial Transplant 2018; 33:514-522. [PMID: 28340119 DOI: 10.1093/ndt/gfx014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/15/2017] [Indexed: 01/12/2023] Open
Abstract
Background Vitamin K (VK)-dependent γ-glutamate carboxylation and serine phosphorylation activate matrix Gla protein (MGP) to a potent locally acting inhibitor of calcification. Nephrolithiasis represents a process of unwanted calcification associated with substantial mortality and high recurrence rates. We hypothesized that the risk of nephrolithiasis increases with VK shortage, as exemplified by higher plasma levels of desphospho-uncarboxylated MGP (dp-ucMGP). Methods In 1748 randomly recruited Flemish individuals (51.1% women; mean age 46.8 years), we determined dp-ucMGP and the prevalence of nephrolithiasis at baseline (April 1996-February 2015) and its incidence during follow-up until March 2016. We estimated the multivariable-adjusted relative risk associated with the doubling of dp-ucMGP, using logistic or Cox regression. We did a Mendelian randomization analysis using four MGP genotypes as instrumental variables. Results With adjustments applied for sex, age and 24-h urinary volume and calcium excretion, the odds of having prevalent nephrolithiasis [n = 144 (8.2%)] associated with dp-ucMGP was 1.31 [95% confidence interval (CI) 1.04-1.64; P = 0.022]. dp-ucMGP levels were associated (P ≤ 0.001) with MGP variants rs2098435, rs4236 and rs2430692. In the Mendelian analysis, the causal odds ratio was 3.82 (95% CI 1.15-12.7; P = 0.029). The incidence of nephrolithiasis over 12.0 years (median) was 37 cases (0.2%). With similar adjustments as before, the hazard ratio in relation to dp-ucMGP was 2.48 (95% CI 1.71-3.61; P < 0.001). Additional adjustment for a nephrolithiasis propensity score produced consistent results. Conclusion Higher levels of inactive dp-ucMGP may be causally associated with the risk of nephrolithiasis. Whether or not VK deficiency plays a role in these observations remains to be firmly established.
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Affiliation(s)
- Fang-Fei Wei
- Studies Coordinating Centre, Research Unit of Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - Lutgarde Thijs
- Studies Coordinating Centre, Research Unit of Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - Zhen-Yu Zhang
- Studies Coordinating Centre, Research Unit of Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - Lotte Jacobs
- Studies Coordinating Centre, Research Unit of Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - Wen-Yi Yang
- Studies Coordinating Centre, Research Unit of Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - Erika Salvi
- Genomics and Bioinformatics Platform at Filarete Foundation, Department of Health Sciences and Graduate School of Nephrology, Division of Nephrology, San Paolo Hospital, University of Milan, Italy
| | - Lorena Citterio
- Division of Nephrology and Dialysis, IRCCS San Raffaele Scientific Institute and School of Nephrology, University Vita-Salute San Raffaele, Milan, Italy
| | - Nicholas Cauwenberghs
- Studies Coordinating Centre, Research Unit of Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - Tatiana Kuznetsova
- Studies Coordinating Centre, Research Unit of Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | | | - Azusa Hara
- Department of Social Pharmacy and Public Health, Showa Pharmaceutical University, Tokyo, Japan
| | - Paolo Manunta
- Division of Nephrology and Dialysis, IRCCS San Raffaele Scientific Institute and School of Nephrology, University Vita-Salute San Raffaele, Milan, Italy
| | - Yan Li
- Center for Epidemiological Studies and Clinical Trials and Center for Vascular Evaluations, Shanghai Institute of Hypertension, Shanghai Key Laboratory of Hypertension, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Peter Verhamme
- Research Unit of Molecular and Vascular Biology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - Karel Allegaert
- Research Unit of Organ Systems, KU Leuven Department of Development and Regeneration, University of Leuven, Leuven, Belgium
| | - Daniele Cusi
- Genomics and Bioinformatics Platform at Filarete Foundation, Department of Health Sciences and Graduate School of Nephrology, Division of Nephrology, San Paolo Hospital, University of Milan, Italy
| | - Cees Vermeer
- R&D Group VitaK, Maastricht University, Maastricht, The Netherlands
| | - Jan A Staessen
- Studies Coordinating Centre, Research Unit of Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
- R&D Group VitaK, Maastricht University, Maastricht, The Netherlands
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13
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Abstract
Although phosphorus is an essential nutrient required for multiple physiological functions, recent research raises concerns that high phosphorus intake could have detrimental effects on health. Phosphorus is abundant in the food supply of developed countries, occurring naturally in protein-rich foods and as an additive in processed foods. High phosphorus intake can cause vascular and renal calcification, renal tubular injury, and premature death in multiple animal models. Small studies in human suggest that high phosphorus intake may result in positive phosphorus balance and correlate with renal calcification and albuminuria. Although serum phosphorus is strongly associated with cardiovascular disease, progression of kidney disease, and death, limited data exist linking high phosphorus intake directly to adverse clinical outcomes. Further prospective studies are needed to determine whether phosphorus intake is a modifiable risk factor for kidney disease.
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Affiliation(s)
- Alex R Chang
- Kidney Health Research Institute, Geisinger Health System, Danville, Pennsylvania 17822; .,Department of Epidemiology and Health Services Research, Geisinger Health System, Geisinger Health System, Danville, Pennsylvania 17822
| | - Cheryl Anderson
- Division of Preventive Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093
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14
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Abreu R, Bento C, Oliveira L, Morgado T. Malabsorption syndrome as a rare cause of nephrocalcinosis. ACTA ACUST UNITED AC 2017; 13:247-248. [PMID: 28228792 DOI: 10.11138/ccmbm/2016.13.3.247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Nephrocalcinosis is characterized by calcification of kidney parenchyma and can be caused by an increased amount of calcium, phosphate or oxalate in urinary excretion. We report a 35-year-old female with nephrocalcinosis. She had fitful steatorrhea since last year. Physical examination was normal. Analytic exams found normal renal function and ionogram. Primary hyperparathyroidism, renal tubular acidosis and sarcoidosis were excluded. Urinalysis showed mild hematuria, without proteinuria and 24-hour urine collection exhibited hyperoxaluria. Patient was submitted to an endoscopy and duodenal biopsy whose histology sustained the diagnosis of celiac disease. Fluid intake increase and gluten and oxalate free diet were initiated.
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Affiliation(s)
- Rui Abreu
- Department of Nephrology, Centro Hospitalar Trás-os-Montes e Alto Douro, Vila Real, Portugal
| | - Cláudia Bento
- Department of Nephrology, Centro Hospitalar Trás-os-Montes e Alto Douro, Vila Real, Portugal
| | - Luís Oliveira
- Department of Nephrology, Centro Hospitalar Trás-os-Montes e Alto Douro, Vila Real, Portugal
| | - Teresa Morgado
- Department of Nephrology, Centro Hospitalar Trás-os-Montes e Alto Douro, Vila Real, Portugal
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15
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Paloian NJ, Leaf EM, Giachelli CM. Osteopontin protects against high phosphate-induced nephrocalcinosis and vascular calcification. Kidney Int 2016; 89:1027-1036. [PMID: 27083280 DOI: 10.1016/j.kint.2015.12.046] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 12/08/2015] [Accepted: 12/30/2015] [Indexed: 01/09/2023]
Abstract
Pathologic calcification is a significant cause of increased morbidity and mortality in patients with chronic kidney disease. The precise mechanisms of ectopic calcification are not fully elucidated, but it is known to be caused by an imbalance of procalcific and anticalcific factors. In the chronic kidney disease population, an elevated phosphate burden is both highly prevalent and a known risk factor for ectopic calcification. Here we tested whether osteopontin, an inhibitor of calcification, protects against high phosphate load-induced nephrocalcinosis and vascular calcification. Osteopontin knockout mice were placed on a high phosphate diet for 11 weeks. Osteopontin deficiency together with phosphate overload caused uremia, nephrocalcinosis characterized by substantial renal tubular and interstitial calcium deposition, and marked vascular calcification when compared with control mice. Although the osteopontin-deficient mice did not exhibit hypercalcemia or hyperphosphatemia, they did show abnormalities in the mineral metabolism hormone fibroblast growth factor-23. Thus, endogenous osteopontin plays a critical role in the prevention of phosphate-induced nephrocalcinosis and vascular calcification in response to high phosphate load. A better understanding of osteopontin's role in phosphate-induced calcification will hopefully lead to better biomarkers and therapies for this disease, especially in patients with chronic kidney disease and other at-risk populations.
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Affiliation(s)
- Neil J Paloian
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Elizabeth M Leaf
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
| | - Cecilia M Giachelli
- Department of Bioengineering, University of Washington, Seattle, Washington, USA.
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