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van Abswoude DH, Pellikaan K, Nguyen N, Rosenberg AGW, Davidse K, Hoekstra FME, Rood IM, Poitou C, Grugni G, Høybye C, Markovic TP, Caixàs A, Crinò A, van den Berg SAA, van der Lely AJ, de Graaff LCG. Corrigendum: Kidney disease in adults with Prader-Willi syndrome: international cohort study and systematic literature review. Front Endocrinol (Lausanne) 2024; 15:1357219. [PMID: 38318297 PMCID: PMC10839894 DOI: 10.3389/fendo.2024.1357219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 01/04/2024] [Indexed: 02/07/2024] Open
Abstract
[This corrects the article DOI: 10.3389/fendo.2023.1168648.].
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Affiliation(s)
- Denise H van Abswoude
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dutch Center of Reference for Prader-Willi Syndrome, Rotterdam, Netherlands
- Academic Center for Growth Disorders, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Karlijn Pellikaan
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dutch Center of Reference for Prader-Willi Syndrome, Rotterdam, Netherlands
- Academic Center for Growth Disorders, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Naomi Nguyen
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Anna G W Rosenberg
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dutch Center of Reference for Prader-Willi Syndrome, Rotterdam, Netherlands
- Academic Center for Growth Disorders, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Kirsten Davidse
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dutch Center of Reference for Prader-Willi Syndrome, Rotterdam, Netherlands
- Academic Center for Growth Disorders, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Franciska M E Hoekstra
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Internal Medicine, Division of Nephrology, Reinier de Graaf Gasthuis, Delft, Netherlands
| | - Ilse M Rood
- Department of Nephrology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, Netherlands
| | - Christine Poitou
- Assistance Publique-Hôpitaux de Paris, Rare Diseases Center of Reference 'Prader-Willi Syndrome and Obesity with Eating Disorders' (PRADORT), Nutrition Department, Institute of Cardiometabolism and Nutrition (ICAN), Pitié-Salpêtrière Hospital, Sorbonne Université, National Institute of Health and Medical Research (INSERM), Nutriomics, Paris, France
- International Network for Research, Management & Education on adults with Prader-Willi Syndrome (INfoRMEd-PWS)
- European Reference Network on Rare Endocrine Conditions (ENDO-ERN)
| | - Graziano Grugni
- International Network for Research, Management & Education on adults with Prader-Willi Syndrome (INfoRMEd-PWS)
- European Reference Network on Rare Endocrine Conditions (ENDO-ERN)
- Division of Auxology, Istituto Auxologico Italiano, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Piancavallo, Italy
| | - Charlotte Høybye
- International Network for Research, Management & Education on adults with Prader-Willi Syndrome (INfoRMEd-PWS)
- European Reference Network on Rare Endocrine Conditions (ENDO-ERN)
- Department of Molecular Medicine and Surgery, Karolinska Institute and Karolinska University Hospital, Stockholm, Sweden
- Department of Endocrinology, Karolinska Institute and Karolinska University Hospital, Stockholm, Sweden
| | - Tania P Markovic
- International Network for Research, Management & Education on adults with Prader-Willi Syndrome (INfoRMEd-PWS)
- Metabolism & Obesity Service, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
- Charles Perkins Center and Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Assumpta Caixàs
- International Network for Research, Management & Education on adults with Prader-Willi Syndrome (INfoRMEd-PWS)
- Department of Endocrinology and Nutrition, Parc Tauli Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT) Instituto de Salud Carlos III (CERCA-ISCIII), Sabadell, Spain
- Department of Medicine, Universitat Autònoma de Barcelona, Sabadell, Spain
| | - Antonino Crinò
- International Network for Research, Management & Education on adults with Prader-Willi Syndrome (INfoRMEd-PWS)
- Reference Center for Prader-Willi syndrome, Bambino Gesù Hospital, Research Institute, Palidoro, Italy
- Center for Rare Diseases and Congenital Defects, Fondazione Policlinico Universitario A. Gemelli, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Rome, Italy
| | - Sjoerd A A van den Berg
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Department of Clinical Chemistry, Erasmus Medical Center (MC), University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Aart J van der Lely
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Academic Center for Growth Disorders, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Laura C G de Graaff
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dutch Center of Reference for Prader-Willi Syndrome, Rotterdam, Netherlands
- Academic Center for Growth Disorders, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- European Reference Network on Rare Endocrine Conditions (ENDO-ERN)
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van Abswoude DH, Pellikaan K, Nguyen N, Rosenberg AGW, Davidse K, Hoekstra FME, Rood IM, Poitou C, Grugni G, Høybye C, Markovic TP, Caixàs A, Crinò A, van den Berg SAA, van der Lely AJ, de Graaff LCG. Kidney disease in adults with Prader-Willi syndrome: international cohort study and systematic literature review. Front Endocrinol (Lausanne) 2023; 14:1168648. [PMID: 37547314 PMCID: PMC10402738 DOI: 10.3389/fendo.2023.1168648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 07/03/2023] [Indexed: 08/08/2023] Open
Abstract
Background Prader-Willi syndrome (PWS) is a rare, complex, genetic disorder characterized by hyperphagia, hypotonia, delayed psychomotor development, low muscle mass and hypothalamic dysfunction. Adults with PWS often have obesity, hypertension and type 2 diabetes mellitus (DM2), known risk factors for cardiovascular disease (CVD) and chronic kidney disease (CKD). Early symptoms of CVD and CKD may be masked by intellectual disability and inability to express physical complaints. Furthermore, kidney diseases are often asymptomatic. Therefore, renal and cardiovascular disease might be missed in patients with PWS. Microalbuminuria is an early sign of microvascular damage in the kidneys and other vascular beds. Therefore, we screened our adult PWS cohort for the presence of elevated urinary albumin and (micro)albuminuria. Methods We retrospectively collected anthropometric measurements, blood pressure, medical history, medication use, urine dipstick and biochemical measurements form electronic patient files. In addition, we performed a systematic literature review on kidney disease in PWS. Results We included 162 adults with genetically confirmed PWS (56% male, median age 28 years), of whom 44 (27%) had DM2. None had known CVD. All subjects had normal estimated glomerular filtration rate (eGFR) according to non-PWS reference intervals. Elevated urinary albumin or (micro)albuminuria was present in 28 (18%); 19 out of 75 (25%) had an increased urinary albumin-to-creatinine ratio (UACR) and 10 out of 57 (18%) had an increased urinary protein-to-creatinine ratio. Elevated urinary albumin was present at a young age (median age 26 (IQR 24-32) years) and was associated with an significantly higher BMI and LDL-cholesterol levels and higher prevalence of DM2, hypertension and dyslipidemia than those with normal UACR (p=0.027, p=0.019, p<0.001, p<0.001, p=0.011 and respectively). Conclusion Upon screening, one in every five adults with PWS had increased urinary albumin or (micro)albuminuria, early signs of microvascular disease. All had normal eGFR, according to non-PWS reference intervals, and none had a formal diagnosis of CVD. As muscle mass is low in PWS, creatinine levels and eGFR may be spuriously normal. Urinalysis in this patient group can be used as a screening tool for microvascular (kidney) disease. We propose an algorithm for the detection and management of microvascular disease in adults with PWS.
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Affiliation(s)
- Denise H. van Abswoude
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dutch Center of Reference for Prader–Willi Syndrome, Rotterdam, Netherlands
- Academic Center for Growth Disorders, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Karlijn Pellikaan
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dutch Center of Reference for Prader–Willi Syndrome, Rotterdam, Netherlands
- Academic Center for Growth Disorders, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Naomi Nguyen
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Anna G. W. Rosenberg
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dutch Center of Reference for Prader–Willi Syndrome, Rotterdam, Netherlands
- Academic Center for Growth Disorders, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Kirsten Davidse
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dutch Center of Reference for Prader–Willi Syndrome, Rotterdam, Netherlands
- Academic Center for Growth Disorders, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Franciska M. E. Hoekstra
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Internal Medicine, Division of Nephrology, Reinier de Graaf Gasthuis, Delft, Netherlands
| | - Ilse M. Rood
- Department of Nephrology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, Netherlands
| | - Christine Poitou
- Assistance Publique-Hôpitaux de Paris, Rare Diseases Center of Reference ‘Prader-Willi Syndrome and Obesity with Eating Disorders’ (PRADORT), Nutrition Department, Institute of Cardiometabolism and Nutrition (ICAN), Pitié-Salpêtrière Hospital, Sorbonne Université, National Institute of Health and Medical Research (INSERM), Nutriomics, Paris, France
- International Network for Research, Management & Education on adults with Prader-Willi Syndrome (INfoRMEd-PWS)
- European Reference Network on Rare Endocrine Conditions (ENDO-ERN)
| | - Graziano Grugni
- International Network for Research, Management & Education on adults with Prader-Willi Syndrome (INfoRMEd-PWS)
- European Reference Network on Rare Endocrine Conditions (ENDO-ERN)
- Division of Auxology, Istituto Auxologico Italiano, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Piancavallo, Italy
| | - Charlotte Høybye
- International Network for Research, Management & Education on adults with Prader-Willi Syndrome (INfoRMEd-PWS)
- European Reference Network on Rare Endocrine Conditions (ENDO-ERN)
- Department of Molecular Medicine and Surgery, Karolinska Institute and Karolinska University Hospital, Stockholm, Sweden
- Department of Endocrinology, Karolinska Institute and Karolinska University Hospital, Stockholm, Sweden
| | - Tania P. Markovic
- International Network for Research, Management & Education on adults with Prader-Willi Syndrome (INfoRMEd-PWS)
- Metabolism & Obesity Service, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
- Charles Perkins Center and Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Assumpta Caixàs
- International Network for Research, Management & Education on adults with Prader-Willi Syndrome (INfoRMEd-PWS)
- Department of Endocrinology and Nutrition, Parc Tauli Hospital Universitari, Institut d’Investigació i Innovació Parc Taulí (I3PT) Instituto de Salud Carlos III (CERCA-ISCIII), Sabadell, Spain
- Department of Medicine, Universitat Autònoma de Barcelona, Sabadell, Spain
| | - Antonino Crinò
- International Network for Research, Management & Education on adults with Prader-Willi Syndrome (INfoRMEd-PWS)
- Reference Center for Prader-Willi syndrome, Bambino Gesù Hospital, Research Institute, Palidoro, Italy
- Center for Rare Diseases and Congenital Defects, Fondazione Policlinico Universitario A. Gemelli, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Rome, Italy
| | - Sjoerd A. A. van den Berg
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Department of Clinical Chemistry, Erasmus Medical Center (MC), University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Aart J. van der Lely
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Academic Center for Growth Disorders, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Laura C. G. de Graaff
- Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Center for Adults with Rare Genetic Syndromes, Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- Dutch Center of Reference for Prader–Willi Syndrome, Rotterdam, Netherlands
- Academic Center for Growth Disorders, Erasmus Medical Center, University Medical Center Rotterdam, Rotterdam, Netherlands
- European Reference Network on Rare Endocrine Conditions (ENDO-ERN)
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Groen In 't Woud S, Rood IM, Steenbergen E, Willemsen B, Dijkman HB, van Geel M, Schoots J, Wetzels JFM, Lugtenberg D, Deegens JKJ, Bongers EMHF. Kidney Disease Associated With Mono-allelic COL4A3 and COL4A4 Variants: A Case Series of 17 Families. Kidney Med 2023; 5:100607. [PMID: 36925663 PMCID: PMC10011433 DOI: 10.1016/j.xkme.2023.100607] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Rationale & Objective Mono-allelic variants in COL4A3 and COL4A4 (COL4A3/COL4A4) have been identified in a spectrum of glomerular basement membrane nephropathies, including thin basement membrane nephropathy and autosomal dominant Alport syndrome. With the increasing use of next generation sequencing, mono-allelic COL4A3/COL4A4 variants are detected more frequently, but phenotypic heterogeneity impedes counseling. We aimed to investigate the phenotypic spectrum, kidney biopsy results, and segregation patterns of patients with mono-allelic COL4A3/COL4A4 variants identified by whole exome sequencing. Study Design Case series. Setting & Participants We evaluated clinical and pathologic characteristics of 17 Dutch index patients with mono-allelic variants in COL4A3/COL4A4 detected by diagnostic whole exome sequencing and 25 affected family members with variants confirmed by Sanger sequencing. Results Eight different mono-allelic COL4A3/COL4A4 variants were identified across members of 11 families, comprising 7 glycine substituted missense variants and 1 frameshift variant. All index patients had microscopic hematuria at clinical presentation (median age 43 years) and 14 had (micro)albuminuria/proteinuria. All family members showed co-segregation of the variant with at least hematuria. At end of follow-up of all 42 individuals (median age 54 years), 16/42 patients had kidney function impairment, of whom 6 had kidney failure. Reports of kidney biopsies of 14 patients described thin basement membrane nephropathy, focal segmental glomerulosclerosis, minimal change lesions, and Alport syndrome. Electron microscopy images of 7 patients showed a significantly thinner glomerular basement membrane compared with images of patients with idiopathic focal segmental glomerulosclerosis and other hereditary glomerular diseases. No genotype-phenotype correlations could be established. Limitations Retrospective design, ascertainment bias toward severe kidney phenotypes, and familial hematuria. Conclusions This study confirms the wide phenotypic spectrum associated with mono-allelic COL4A3/COL4A4 variants, extending from isolated microscopic hematuria to kidney failure with high intra- and interfamilial variability.
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Affiliation(s)
- Sander Groen In 't Woud
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Department for Health Evidence, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ilse M Rood
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Eric Steenbergen
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Brigith Willemsen
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Henry B Dijkman
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Michel van Geel
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Jeroen Schoots
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jack F M Wetzels
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Dorien Lugtenberg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen K J Deegens
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ernie M H F Bongers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
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Rood IM, Bavinck A, Lipska-Ziętkiewicz BS, Lugtenberg D, Schaefer F, Deegens JK, Wetzels JF. Later Response to Corticosteroids in Adults With Primary Focal Segmental Glomerular Sclerosis Is Associated With Favorable Outcomes. Kidney Int Rep 2022; 7:87-98. [PMID: 35005317 PMCID: PMC8720814 DOI: 10.1016/j.ekir.2021.10.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/07/2021] [Accepted: 10/15/2021] [Indexed: 12/26/2022] Open
Abstract
INTRODUCTION Guidelines advise initial therapy with corticosteroids (CSs) in patients with presumed primary focal segmental glomerular sclerosis (pFSGS). Many patients do not achieve complete remission (CR) after 8 or 16 weeks. Although these patients are considered steroid resistant, clinical outcomes are ill defined. METHODS A retrospective cohort study of patients with pFSGS who were referred between January 1995 and December 2014. Data of clinical presentation until last follow-up were collected from patient records. RESULTS A total of 51 patients (median age 47 years, 20 female/31 male) were included (median follow-up 7.1 years). There were 10 patients who achieved partial response (PR) at 8 weeks. High-dose CS monotherapy was continued for a median of 17 weeks (interquartile range [IQR] 11-21 weeks) (total duration 56 weeks [IQR 28-83 weeks]). With CSs, the cumulative incidence of CR + PR was 18% and 35%, respectively. Of 24 patients with persistent nephrotic-range proteinuria, 22 received additional immunosuppressive (IS) therapy, resulting in CR in 3 (14%) and PR in 11 patients (50%). A decrease of >20% of proteinuria at 8 weeks predicted response. In addition, 8 patients (36%) were considered primary nonresponders. A genetic cause was found in 2 patients. Proteinuria at end of follow-up was 1.2 g (IQR 0.4-3.0 g/24 hours or g/10 mmol creatinine). Renal survival at 3, 5, and 10 years was 92%, 87%, and 64%, respectively. CONCLUSION Patients with presumed pFSGS often respond late to IS therapy. A decrease in proteinuria of >20% after 8 weeks of therapy is a predictor of responsiveness. Regardless of CR in some patients, improved biomarkers are needed to predict response/outcomes in patients with pFSGS.
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Affiliation(s)
- Ilse M. Rood
- Department of Nephrology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
| | - Aernoud Bavinck
- Department of Nephrology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
| | - Beata S. Lipska-Ziętkiewicz
- Rare Diseases Centre and Clinical Genetics Unit, Department of Biology and Medical Genetics, Medical University of Gdansk, Gdansk, Poland
| | - Dorien Lugtenberg
- Department of Human Genetics, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
| | - Franz Schaefer
- Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, Heidelberg, Germany
| | - Jeroen K.J. Deegens
- Department of Nephrology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
| | - Jack F.M. Wetzels
- Department of Nephrology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands
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Merchant ML, Barati MT, Caster DJ, Hata JL, Hobeika L, Coventry S, Brier ME, Wilkey DW, Li M, Rood IM, Deegens JK, Wetzels JF, Larsen CP, Troost JP, Hodgin JB, Mariani LH, Kretzler M, Klein JB, McLeish KR. Proteomic Analysis Identifies Distinct Glomerular Extracellular Matrix in Collapsing Focal Segmental Glomerulosclerosis. J Am Soc Nephrol 2020; 31:1883-1904. [PMID: 32561683 DOI: 10.1681/asn.2019070696] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Accepted: 04/13/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND The mechanisms leading to extracellular matrix (ECM) replacement of areas of glomerular capillaries in histologic variants of FSGS are unknown. This study used proteomics to test the hypothesis that glomerular ECM composition in collapsing FSGS (cFSGS) differs from that of other variants. METHODS ECM proteins in glomeruli from biopsy specimens of patients with FSGS not otherwise specified (FSGS-NOS) or cFSGS and from normal controls were distinguished and quantified using mass spectrometry, verified and localized using immunohistochemistry (IHC) and confocal microscopy, and assessed for gene expression. The analysis also quantified urinary excretion of ECM proteins and peptides. RESULTS Of 58 ECM proteins that differed in abundance between cFSGS and FSGS-NOS, 41 were more abundant in cFSGS and 17 in FSGS-NOS. IHC showed that glomerular tuft staining for cathepsin B, cathepsin C, and annexin A3 in cFSGS was significantly greater than in other FSGS variants, in minimal change disease, or in membranous nephropathy. Annexin A3 colocalized with cathepsin B and C, claudin-1, phosphorylated ERK1/2, and CD44, but not with synaptopodin, in parietal epithelial cells (PECs) infiltrating cFSGS glomeruli. Transcripts for cathepsins B and C were increased in FSGS glomeruli compared with normal controls, and urinary excretion of both cathepsins was significantly greater in cFSGS compared with FSGS-NOS. Urinary excretion of ECM-derived peptides was enhanced in cFSGS, although in silico analysis did not identify enhanced excretion of peptides derived from cathepsin B or C. CONCLUSIONS ECM differences suggest that glomerular sclerosis in cFSGS differs from that in other FSGS variants. Infiltration of activated PECs may disrupt ECM remodeling in cFSGS. These cells and their cathepsins may be therapeutic targets.
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Affiliation(s)
- Michael L Merchant
- Division of Nephrology and Hypertension, Department of Medicine, University of Louisville, Louisville, Kentucky
| | - Michelle T Barati
- Division of Nephrology and Hypertension, Department of Medicine, University of Louisville, Louisville, Kentucky
| | - Dawn J Caster
- Division of Nephrology and Hypertension, Department of Medicine, University of Louisville, Louisville, Kentucky
| | - Jessica L Hata
- Pathology Department, Norton Children's Hospital, Louisville, Kentucky
| | - Liliane Hobeika
- Division of Nephrology, Department of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Susan Coventry
- Pathology Department, Norton Children's Hospital, Louisville, Kentucky
| | - Michael E Brier
- Division of Nephrology and Hypertension, Department of Medicine, University of Louisville, Louisville, Kentucky
| | - Daniel W Wilkey
- Division of Nephrology and Hypertension, Department of Medicine, University of Louisville, Louisville, Kentucky
| | - Ming Li
- Division of Nephrology and Hypertension, Department of Medicine, University of Louisville, Louisville, Kentucky
| | - Ilse M Rood
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen K Deegens
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jack F Wetzels
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Jonathan P Troost
- Michigan Institute for Clinical and Health Research, University of Michigan, Ann Arbor, Michigan
| | - Jeffrey B Hodgin
- Division of Pathology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Laura H Mariani
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Matthias Kretzler
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Jon B Klein
- Division of Nephrology and Hypertension, Department of Medicine, University of Louisville, Louisville, Kentucky.,Robley Rex Veterans Affairs Medical Center, Louisville, Kentucky
| | - Kenneth R McLeish
- Division of Nephrology and Hypertension, Department of Medicine, University of Louisville, Louisville, Kentucky
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Rood IM. In Reply to ‘Critical Considerations in Genetic Counseling of Patients With the NPHS2 R229Q Variant’. Am J Kidney Dis 2019; 73:576-577. [DOI: 10.1053/j.ajkd.2018.12.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 12/11/2018] [Indexed: 11/11/2022]
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Boulangé CL, Rood IM, Posma JM, Lindon JC, Holmes E, Wetzels JFM, Deegens JKJ, Kaluarachchi MR. NMR and MS urinary metabolic phenotyping in kidney diseases is fit-for-purpose in the presence of a protease inhibitor. Mol Omics 2019; 15:39-49. [DOI: 10.1039/c8mo00190a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
When using an appropriate data analysis pipeline, protease inhibitor (PI)-containing urine samples are fit-for-purpose for metabolic phenotyping of patients with nephrotic syndrome and proteinuria.
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Affiliation(s)
| | - Ilse M. Rood
- Department of Nephrology
- Radboud University Medical Center
- Nijmegen
- The Netherlands
| | - Joram M. Posma
- Imperial College London
- Division of Computational and Systems Medicine
- Department of Surgery and Cancer
- Faculty of Medicine
- London SW7 2AZ
| | - John C. Lindon
- Metabometrix Ltd
- London SW7 2AZ
- UK
- Imperial College London
- Division of Computational and Systems Medicine
| | - Elaine Holmes
- Metabometrix Ltd
- London SW7 2AZ
- UK
- Imperial College London
- Division of Computational and Systems Medicine
| | - Jack F. M. Wetzels
- Department of Nephrology
- Radboud University Medical Center
- Nijmegen
- The Netherlands
| | - Jeroen K. J. Deegens
- Department of Nephrology
- Radboud University Medical Center
- Nijmegen
- The Netherlands
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8
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Rood IM, Deegens JKJ, Lugtenberg D, Bongers EMHF, Wetzels JFM. Nephrotic Syndrome With Mutations in NPHS2: The Role of R229Q and Implications for Genetic Counseling. Am J Kidney Dis 2018; 73:400-403. [PMID: 30241959 DOI: 10.1053/j.ajkd.2018.06.034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 06/28/2018] [Indexed: 12/17/2022]
Abstract
Mutations in the NPHS2 gene, which encodes the podocyte slit diaphragm protein podocin, cause autosomal recessive steroid-resistant nephrotic syndrome (Online Mendelian Inheritance in Man [OMIM] #600995). Basic research and clinical studies have provided important insights about genotype-phenotype correlations. This knowledge allows personalized genetic (risk) counseling and should lead to changes in the advice given to patients. A patient who carries the R229Q variant (which has a high allele frequency of 3.7% in the European population) in combination with a pathogenic variant in exon 7 or 8 is at high risk for developing nephrotic syndrome that may not manifest before adulthood, whereas a patient with 2 pathogenic variants will develop congenital or childhood-onset nephrotic syndrome. In contrast, a patient who carries the R229Q variant in combination with a pathogenic variant in exons 1 to 6 is unlikely to develop nephrotic syndrome. In this article, we review the emerging knowledge about the NPHS2 gene and translate these findings from the bench to practical advice for the clinical bedside.
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Affiliation(s)
- Ilse M Rood
- Department of Nephrology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, the Netherlands.
| | - Jeroen K J Deegens
- Department of Nephrology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, the Netherlands
| | - Dorien Lugtenberg
- Department of Human Genetics, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, the Netherlands
| | - Ernie M H F Bongers
- Department of Human Genetics, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, the Netherlands
| | - Jack F M Wetzels
- Department of Nephrology, Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, the Netherlands
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9
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Rood IM, Seijger CGW, van Waarde JA, de Maat MMR, Verhave JC, Blans MJ. [Hypernatremia caused by treatment with GHB obtained via a doctor's prescription]. Tijdschr Psychiatr 2017; 59:47-51. [PMID: 28098924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In the last few years, gamma hydroxybutyric acid (GHB) has been used increasingly as a party drug; this has led to a marked increase in the number of requests for professional help with the treatment of GHB addiction. Pharmaceutical GHB (sodium oxybate, the sodium-salt of GHB), registered for cataplexia in narcolepsy patients, is used off-label to treat the withdrawal symptoms associated with GHB addiction. Pharmaceutical GHB has a high sodium load. In this report we present the cases of two patients who developed symptomatic hypernatremia following treatment with pharmaceutical GHB and who thereafter needed intensive care for the severe withdrawal symptoms that they experienced.
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10
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Rood IM, Bongers EMHF, Lugtenberg D, Klein IHHT, Steenbergen EJ, Wetzels JFM, Deegens JKJ. Familial focal segmental glomerulosclerosis: mutation in inverted formin 2 mimicking Alport syndrome. Neth J Med 2016; 74:82-85. [PMID: 26951353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Focal segmental glomerulosclerosis (FSGS) is one of the most common patterns of glomerular injury. FSGS can be caused by mutations in genes encoding proteins that play key roles in the function of the podocyte and glomerular basement membrane. In this case report we present a family with FSGS initially suspected to be Alport syndrome. Genetic analysis according to the Dutch guidelines of FSGS revealed a mutation in INF2.
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Affiliation(s)
- I M Rood
- Department of Nephrology, Radboud University Medical Centre, Nijmegen
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11
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Rood IM, Merchant ML, Wilkey DW, Zhang T, Zabrouskov V, van der Vlag J, Dijkman HB, Willemsen BK, Wetzels JF, Klein JB, Deegens JK. Increased expression of lysosome membrane protein 2 in glomeruli of patients with idiopathic membranous nephropathy. Proteomics 2015; 15:3722-30. [PMID: 26304790 DOI: 10.1002/pmic.201500127] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 07/13/2015] [Accepted: 08/18/2015] [Indexed: 11/10/2022]
Abstract
Urinary microvesicles constitute a rich source of membrane-bound and intracellular proteins that may provide important clues of pathophysiological mechanisms in renal disease. In the current study, we analyzed and compared the proteome of urinary microvesicles from patients with idiopathic membranous nephropathy (iMN), idiopathic focal segmental glomerulosclerosis (iFSGS), and normal controls using an approach that combined both proteomics and pathology analysis. Lysosome membrane protein-2 (LIMP-2) was increased greater than twofold in urinary microvesicles obtained from patients with iMN compared to microvesicles of patients with iFSGS and normal controls. Immunofluorescence analysis of renal biopsies confirmed our proteomics findings that LIMP-2 was upregulated in glomeruli from patients with iMN but not in glomeruli of diseased patients (iFSGS, minimal change nephropathy, IgA nephropathy, membranoproliferative glomerulonephritis) and normal controls. Confocal laser microscopy showed co-localization of LIMP-2 with IgG along the glomerular basement membrane. Serum antibodies against LIMP-2 could not be detected. In conclusion, our data show the value of urinary microvesicles in biomarker discovery and provide evidence for de novo expression of LIMP-2 in glomeruli of patients with iMN.
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Affiliation(s)
- Ilse M Rood
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Michael L Merchant
- Kidney Disease Program and Clinical Proteomics Center, University of Louisville, Louisville, KY, USA
| | - Daniel W Wilkey
- Kidney Disease Program and Clinical Proteomics Center, University of Louisville, Louisville, KY, USA
| | | | | | - Johan van der Vlag
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Henry B Dijkman
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Brigith K Willemsen
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jack F Wetzels
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jon B Klein
- Kidney Disease Program and Clinical Proteomics Center, University of Louisville, Louisville, KY, USA
- Veterans Administration Medical Center, Louisville, KY, USA
| | - Jeroen K Deegens
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
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12
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Rood IM, Huussen J, Wetzels JF, Deegens JK. Rituximab can induce remission of nephrotic syndrome in the absence of peripheral B-cells. Nephrology (Carlton) 2015; 20:667-8. [DOI: 10.1111/nep.12492] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/16/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Ilse M Rood
- Department of Nephrology; Radboud Institute for Health Sciences; Radboud University Medical Center; Nijmegen The Netherlands
| | - Job Huussen
- Department of Internal Medicine; Slingeland Hospital; Doetinchem The Netherlands
| | - Jack F Wetzels
- Department of Nephrology; Radboud Institute for Health Sciences; Radboud University Medical Center; Nijmegen The Netherlands
| | - Jeroen K Deegens
- Department of Nephrology; Radboud Institute for Health Sciences; Radboud University Medical Center; Nijmegen The Netherlands
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13
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Rood IM, Hofstra JM, Deegens JK, Wetzels JF. B cell suppression in primary glomerular disease. Adv Chronic Kidney Dis 2014; 21:166-81. [PMID: 24602466 DOI: 10.1053/j.ackd.2014.01.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 01/06/2014] [Accepted: 01/07/2014] [Indexed: 12/23/2022]
Abstract
Membranous nephropathy, focal segmental glomerulosclerosis (FSGS), and minimal change disease (MCD) are the most common causes of idiopathic nephrotic syndrome. For many years prednisone, alkylating agents, and calcineurin inhibitors have been the standard of therapy for these patients. More effective or better tolerated treatment modalities are needed. B cell targeted therapy was recently introduced in clinical practice. In this review, we briefly summarize the current standard therapy and discuss the efficacy of B cell targeted therapy in primary glomerular diseases. Observational, short-term studies suggest that rituximab is effective and comparable to standard therapy in maintaining remissions in patients with frequently relapsing or steroid-dependent MCD or FSGS. In contrast, response is limited in patients with steroid-resistant nephrotic syndrome. Rituximab also induces remissions in patients with membranous nephropathy. Controlled clinical trials on kidney endpoints are urgently needed to position B cell targeted therapy in clinical practice.
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Rood IM, Deegens JKJ, Wetzels JFM. Genetic causes of focal segmental glomerulosclerosis: implications for clinical practice. Nephrol Dial Transplant 2012; 27:882-90. [PMID: 22334613 DOI: 10.1093/ndt/gfr771] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a common cause of steroid-resistant nephrotic syndrome in children and adults. Although FSGS is considered a podocyte disease, the aetiology is diverse. In recent years, many inheritable genetic forms of FSGS have been described, caused by mutations in proteins that are important for podocyte function. In the present commentary, we review these genetic causes of FSGS and describe their prevalence in familial and sporadic FSGS. In routine clinical practice, the decision to perform the costly DNA analysis should be based on the assessment if the results affect the care of the individual patient with respect to the evaluation of extra-renal manifestations, treatment decisions, transplantation and genetic counselling.
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Affiliation(s)
- Ilse M Rood
- Department of Nephrology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
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15
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Rood IM, Lieverse LG, Steenbergen EJ, Wetzels JF, Deegens JK. Spontaneous remission of immunotactoid glomerulopathy. Neth J Med 2011; 69:341-344. [PMID: 21934180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Immunotactoid glomerulopathy (ITG ) is a rare cause of nephrotic syndrome, occurring in approximately 0.1% of native kidney biopsies. We describe a 43-year-old woman who presented with a nephrotic syndrome. Renal biopsy revealed a membranous pattern of glomerular injury. In electron microscopy the subepithelial deposits were comprised of 40 nm wide tubular structures, confirming ITG . During follow-up the patient developed a remission of proteinuria with only supportive treatment.
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Affiliation(s)
- I M Rood
- Department of Nephrology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
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16
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Rood IM, Deegens JKJ, Merchant ML, Tamboer WPM, Wilkey DW, Wetzels JFM, Klein JB. Comparison of three methods for isolation of urinary microvesicles to identify biomarkers of nephrotic syndrome. Kidney Int 2010; 78:810-6. [PMID: 20686450 DOI: 10.1038/ki.2010.262] [Citation(s) in RCA: 194] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Urinary microvesicles, such as 40-100 nm exosomes and 100-1000 nm microparticles, contain many proteins that may serve as biomarkers of renal disease. Microvesicles have been isolated by ultracentrifugation or nanomembrane ultrafiltration from normal urine; however, little is known about the efficiency of these methods in isolating microvesicles from patients with nephrotic-range proteinuria. Here we compared three techniques to isolate microvesicles from nephrotic urine: nanomembrane ultrafiltration, ultracentrifugation, and ultracentrifugation followed by size-exclusion chromatography (UC-SEC). Highly abundant urinary proteins were still present in sufficient quantity after ultrafiltration or ultracentrifugation to blunt detection of less abundant microvesicular proteins by MALDI-TOF-TOF mass spectrometry. The microvesicular markers neprilysin, aquaporin-2, and podocalyxin were highly enriched following UC-SEC compared with preparations by ultrafiltration or ultracentrifugation alone. Electron microscopy of the UC-SEC fractions found microvesicles of varying size, compatible with the presence of both exosomes and microparticles. Thus, UC-SEC following ultracentrifugation to further enrich and purify microparticles facilitates the search for prognostic biomarkers that might be used to predict the clinical course of nephrotic syndrome.
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Affiliation(s)
- Ilse M Rood
- Department of Nephrology, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands
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Merchant ML, Powell DW, Wilkey DW, Cummins TD, Deegens JK, Rood IM, McAfee KJ, Fleischer C, Klein E, Klein JB. Microfiltration isolation of human urinary exosomes for characterization by MS. Proteomics Clin Appl 2009; 4:84-96. [PMID: 21137018 DOI: 10.1002/prca.200800093] [Citation(s) in RCA: 155] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2008] [Revised: 09/14/2009] [Accepted: 09/28/2009] [Indexed: 12/12/2022]
Abstract
PURPOSE The purpose of this study was to address the hypothesis that small vesicular urinary particles known as exosomes could be selectively microfiltered using low protein-binding size exclusion filters, thereby simplifying their use in clinical biomarker discovery studies. EXPERIMENTAL DESIGN We characterized a microfiltration approach using a low protein binding, hydrophilized polyvinylidene difluoride membrane to easily and efficiently isolate urinary exosomes from fresh, room temperature or 4°C urine, with a simultaneous depletion of abundant urinary proteins. Using LC-MS, immunoblot analysis, and electron microscopy methods, we demonstrate this method to isolate intact exosomes and thereby enrich for a low abundant urinary proteome. RESULTS In comparison to other standard methods of exosome isolation including ultracentrifugation and nanofiltration, we demonstrate equivalent enrichment of the exosome proteome with reduced co-purification of abundant urinary proteins. CONCLUSION AND CLINICAL RELEVANCE In conclusion, we demonstrate a microfiltration isolation method that preserves the exosome structure, reduces contamination from higher abundant urinary proteins, and can be easily implemented into mass spectrometry analysis for biomarker discovery efforts or incorporation into routine clinical laboratory applications to yield higher sample throughput.
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