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Yoon J, Liu Z, Alaba M, Bruggeman LA, Janmey P, Arana C, Ayenuyo O, Medeiros I, Nair V, Eddy S, Kretzler M, Henderson JM, Naik A, Chang AN, Miller RT. Glomerular Elasticity and Gene Expression Patterns Define Two Phases of Alport Nephropathy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.26.582201. [PMID: 38948788 PMCID: PMC11212921 DOI: 10.1101/2024.02.26.582201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2024]
Abstract
RATIONALE Early steps in glomerular injury are poorly understood in collagen IV nephropathies. OBJECTIVES We characterized structural, functional, and biophysical properties of glomerular capillaries and podocytes in Col4α3-/- mice and analyzed kidney cortex transcriptional profiles at various disease stages. We investigated the effects of TUDCA (suppresses ER stress) on these parameters and used human FSGS transcriptomic data to identify pathways rescued by TUDCA. FINDINGS In Col4α3-/- mice, podocyte injury develops by 3 months, with maximum glomerular deformability and 40% podocyte loss at 4 months. This period is followed is followed by glomerular capillary stiffening, proteinuria, reduced renal function, inflammatory infiltrates, and fibrosis. Bulk RNA sequencing at sequential time points revealed progressive increases in inflammatory and injury gene expression, and activation of the TNF pathway. Mapping Podocyte-enriched genes from FSGS patients to mice showed that TUDCA, which mitigated renal injury suppressed molecular pathways associated with podocyte stress, hypertrophy and tubulo-interstitial injury. CONCLUSIONS Col4α3-/- nephropathy progresses in two phases. The first is characterized by podocytopathy, increased glomerular capillary deformability and accelerated podocyte loss, and the second by increased capillary wall stiffening and renal inflammatory and profibrotic pathway activation. The response of podocytes to TUDCA treatment provides insights into signaling pathways in Alport and related nephropathies.
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2
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Puapatanakul P, Isaranuwatchai S, Chanakul A, Surintrspanont J, Iampenkhae K, Kanjanabuch T, Suphapeetiporn K, Charu V, Suleiman HY, Praditpornsilpa K, Miner JH. Quantitative assessment of glomerular basement membrane collagen IV α chains in paraffin sections from patients with focal segmental glomerulosclerosis and Alport gene variants. Kidney Int 2024; 105:1049-1057. [PMID: 38401706 PMCID: PMC11032260 DOI: 10.1016/j.kint.2024.01.036] [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: 07/08/2023] [Revised: 01/05/2024] [Accepted: 01/12/2024] [Indexed: 02/26/2024]
Abstract
Focal segmental glomerulosclerosis (FSGS) lesions have been linked to variants in COL4A3/A4/A5 genes, which are also mutated in Alport syndrome. Although it could be useful for diagnosis, quantitative evaluation of glomerular basement membrane (GBM) type IV collagen (colIV) networks is not widely used to assess these patients. To do so, we developed immunofluorescence imaging for collagen α5(IV) and α1/2(IV) on kidney paraffin sections with Airyscan confocal microscopy that clearly distinguishes GBM collagen α3α4α5(IV) and α1α1α2(IV) as two distinct layers, allowing quantitative assessment of both colIV networks. The ratios of collagen α5(IV):α1/2(IV) mean fluorescence intensities (α5:α1/2 intensity ratios) and thicknesses (α5:α1/2 thickness ratios) were calculated to represent the levels of collagen α3α4α5(IV) relative to α1α1α2(IV). The α5:α1/2 intensity and thickness ratios were comparable across all 11 control samples, while both ratios were significantly and markedly decreased in all patients with pathogenic or likely pathogenic Alport COL4A variants, supporting validity of this approach. Thus, with further validation of this technique, quantitative measurement of GBM colIV subtype abundance by immunofluorescence, may potentially serve to identify the subgroup of patients with FSGS lesions likely to harbor pathogenic COL4A variants who could benefit from genetic testing.
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Affiliation(s)
- Pongpratch Puapatanakul
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Suramath Isaranuwatchai
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Division of Nephrology, Department of Internal Medicine, Chulabhorn Hospital, Chulabhorn Royal Academy, Bangkok, Thailand
| | - Ankanee Chanakul
- Division of Nephrology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Jerasit Surintrspanont
- Department of Pathology, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, Thailand; Special Task Force for Activating Research, Department of Pathology, Chulalongkorn University, Bangkok, Thailand
| | - Kroonpong Iampenkhae
- Department of Pathology, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, Thailand
| | - Talerngsak Kanjanabuch
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Center of Excellence in Kidney Metabolic Disorders, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Kanya Suphapeetiporn
- Division of Medical Genetics and Metabolism, Center of Excellence for Medical Genomics, Department of Pediatrics, Medical Genomic Cluster, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, Thailand
| | - Vivek Charu
- Department of Pathology, Institute of Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - Hani Y Suleiman
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Kearkiat Praditpornsilpa
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Jeffrey H Miner
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA.
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Gooley K, Williams P, Mack H, Zhu V, Langsford D, Pianta T, Barit D, Mahmood K, Savige J. A comparison of the ocular features in Pierson and Alport syndrome: a case report and literature review. Ophthalmic Genet 2023; 44:417-422. [PMID: 37537573 DOI: 10.1080/13816810.2023.2240881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 06/24/2023] [Accepted: 07/20/2023] [Indexed: 08/05/2023]
Abstract
BACKGROUND Pierson syndrome and X-linked Alport syndrome result from pathogenic variants in LAMB2 and COL4A5, respectively, and both affect basement membranes in the kidney and the eye. This study describes the ocular features in an individual with a homozygous LAMB2 pathogenic variant and compares the reported abnormalities in Pierson syndrome with those in Alport syndrome. METHODS A 28-year-old man who developed kidney failure 10 years previously and subsequently had an atrial septal defect repair was suspected of having genetic kidney disease on the basis of his likely diagnosis of Focal and Segmental Glomerulosclerosis (FSGS), his young age at presentation, and his cardiac anomaly. He then underwent Whole Exome Sequencing and a formal ophthalmological examination. RESULTS The patient was found to have a homozygous Likely Pathogenic missense variant (p.(Arg1719Cys)) in LAMB2 consistent with the diagnosis of Pierson syndrome. He had normal visual acuity, normal optic globe and cornea size, and normal lens appearance on direct examination. Upon further testing, his cornea demonstrated central thinning. There was also increased corneal endothelial pleomorphism, a reduced foveal reflex, and a blunted foveal curvature, similar to the features seen in X-linked Alport syndrome. CONCLUSION Our patient had a later onset form of Pierson syndrome or "FSGS type 5, with or without ocular abnormalities," consistent with his "milder" LAMB2 missense variant. The resemblance of the ocular features in Pierson syndrome and X-linked Alport syndrome suggests that mutations in LAMB2 and COL4A5 have similar effects on basement membranes and the pathogenesis of ocular damage.
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Affiliation(s)
- Kieran Gooley
- Department of Medicine (Melbourne Health and Northern Health), The University of Melbourne, Parkville, Australia
| | - Peter Williams
- Department of Medicine (Melbourne Health and Northern Health), The University of Melbourne, Parkville, Australia
| | - Heather Mack
- Department of Ophthalmology, The University of Melbourne, East Melbourne, Australia
| | - Victor Zhu
- Department of Medicine (Melbourne Health and Northern Health), The University of Melbourne, Parkville, Australia
| | | | - Tim Pianta
- Renal Unit, Northern Health, Epping, Australia
| | - David Barit
- Renal Unit, Northern Health, Epping, Australia
| | - Khalid Mahmood
- Melbourne Bioinformatics, The University of Melbourne, Parkville, Australia
| | - Judy Savige
- Department of Medicine (Melbourne Health and Northern Health), The University of Melbourne, Parkville, Australia
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Deltas C, Papagregoriou G, Louka SF, Malatras A, Flinter F, Gale DP, Gear S, Gross O, Hoefele J, Lennon R, Miner JH, Renieri A, Savige J, Turner AN. Genetic Modifiers of Mendelian Monogenic Collagen IV Nephropathies in Humans and Mice. Genes (Basel) 2023; 14:1686. [PMID: 37761826 PMCID: PMC10530214 DOI: 10.3390/genes14091686] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 08/09/2023] [Accepted: 08/17/2023] [Indexed: 09/29/2023] Open
Abstract
Familial hematuria is a clinical sign of a genetically heterogeneous group of conditions, accompanied by broad inter- and intrafamilial variable expressivity. The most frequent condition is caused by pathogenic (or likely pathogenic) variants in the collagen-IV genes, COL4A3/A4/A5. Pathogenic variants in COL4A5 are responsible for the severe X-linked glomerulopathy, Alport syndrome (AS), while homozygous or compound heterozygous variants in the COL4A3 or the COL4A4 gene cause autosomal recessive AS. AS usually leads to progressive kidney failure before the age of 40-years when left untreated. People who inherit heterozygous COL4A3/A4 variants are at-risk of a slowly progressive form of the disease, starting with microscopic hematuria in early childhood, developing Alport spectrum nephropathy. Sometimes, they are diagnosed with benign familial hematuria, and sometimes with autosomal dominant AS. At diagnosis, they often show thin basement membrane nephropathy, reflecting the uniform thin glomerular basement membrane lesion, inherited as an autosomal dominant condition. On a long follow-up, most patients will retain normal or mildly affected kidney function, while a substantial proportion will develop chronic kidney disease (CKD), even kidney failure at an average age of 55-years. A question that remains unanswered is how to distinguish those patients with AS or with heterozygous COL4A3/A4 variants who will manifest a more aggressive kidney function decline, requiring prompt medical intervention. The hypothesis that a subgroup of patients coinherit additional genetic modifiers that exacerbate their clinical course has been investigated by several researchers. Here, we review all publications that describe the potential role of candidate genetic modifiers in patients and include a summary of studies in AS mouse models.
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Affiliation(s)
- Constantinos Deltas
- School of Medicine, University of Cyprus, Nicosia 2109, Cyprus
- biobank.cy Center of Excellence in Biobanking and Biomedical Research, University of Cyprus, Nicosia 2109, Cyprus
| | - Gregory Papagregoriou
- biobank.cy Center of Excellence in Biobanking and Biomedical Research, University of Cyprus, Nicosia 2109, Cyprus
| | - Stavroula F. Louka
- biobank.cy Center of Excellence in Biobanking and Biomedical Research, University of Cyprus, Nicosia 2109, Cyprus
| | - Apostolos Malatras
- biobank.cy Center of Excellence in Biobanking and Biomedical Research, University of Cyprus, Nicosia 2109, Cyprus
| | - Frances Flinter
- Clinical Genetics Department, Guy’s & St Thomas’ NHS Foundation Trust, London SE1 9RT, UK
| | - Daniel P. Gale
- Department of Renal Medicine, University College London, London NW3 2PF, UK
| | | | - Oliver Gross
- Clinic for Nephrology and Rheumatology, University Medicine Goettingen, 37075 Goettingen, Germany
| | - Julia Hoefele
- Institute of Human Genetics, Klinikum Rechts der Isar, School of Medicine & Health, Technical University Munich, 81675 Munich, Germany
| | - Rachel Lennon
- Wellcome Centre for Cell-Matrix Research, University of Manchester, Manchester M13 9WU, UK
| | - Jeffrey H. Miner
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Alessandra Renieri
- Medical Genetics, University of Siena, 53100 Siena, Italy
- Med Biotech Hub and Competence Center, Department of Medical Biotechnologies, University of Siena, 53100 Siena, Italy
- Genetica Medica, Azienda Ospedaliero-Universitaria Senese, 53100 Siena, Italy
| | - Judy Savige
- Department of Medicine (Melbourne Health and Northern Health), The University of Melbourne, Parkville, VIC 3052, Australia
| | - A. Neil Turner
- Renal Medicine, Royal Infirmary, University of Edinburgh, Edinburgh EH16 4UX, UK
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Sobh MM, El Kannishy G, Moustafa F, Eid R, Hamdy N, Tharwat S. Role of detached podocytes in differentiating between minimal change disease and early focal segmental glomerulosclerosis, can we rely on routine light microscopy? J Nephrol 2022; 35:2313-2324. [PMID: 36350562 PMCID: PMC9700609 DOI: 10.1007/s40620-022-01456-0] [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: 02/11/2022] [Accepted: 08/28/2022] [Indexed: 11/10/2022]
Abstract
BACKGROUND Detachment of podocytes represents a turning point in the development of glomerular sclerosis and consequently, of CKD progression. Furthermore, detachment may differentiate minimal change disease (MCD) cases-which have only podocyte effacement-from early focal segmental glomerulosclerosis (FSGS) in which effacement and detachment are observed by electron microscopy. Noteworthy, it is not uncommon for early FSGS to present with clinical presentation and light microscopy (LM) pictures identical to MCD. In our routine practice, we often find cells that lie freely in Bowman's space by LM. In this study, we try to determine whether these cells are detached podocytes that are worth reporting or just an artifact that can be ignored. METHODS To the best of our knowledge, no study has discussed the accuracy of LM in detecting detached podocytes by the routinely used stains. We retrospectively selected 118 cases that were diagnosed as MCD by LM, and searched for detached cells in Bowman's space in their archived, routinely stained LM slides. After that, we tried to find any correlation between the clinical course, detached cells in LM picture and the EM reports. RESULTS LM can significantly detect detached podocytes with a positive predictive value of 93%, specificity of 85%, and sensitivity of 46%. Significant correlations were found between detached cells and degree of proteinuria and late steroid resistance. CONCLUSION Detecting detached podocytes by LM is a specific finding that must be reported whenever detected, as it predicts response to steroids and may be able to differentiate MCD from early FSGS by identifying patients who could have podocytopenia.
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Affiliation(s)
- Mahmoud M Sobh
- Mansoura Nephrology and Dialysis Unit (MNDU), Faculty of Medicine, Mansoura University, Mansoura, Egypt.
| | - Ghada El Kannishy
- Mansoura Nephrology and Dialysis Unit (MNDU), Faculty of Medicine, Mansoura University, Mansoura, Egypt
| | - Fatma Moustafa
- Department of Pathology, Faculty of Medicine, Mansoura University, Mansoura, Egypt
| | - Riham Eid
- Nephrology Unit, Mansoura University Children's Hospital, Faculty of Medicine, Mansoura University, Mansoura, Egypt
| | - Nashwa Hamdy
- Nephrology Unit, Mansoura University Children's Hospital, Faculty of Medicine, Mansoura University, Mansoura, Egypt
| | - Samar Tharwat
- Rheumatology and Immunology Unit, Internal Medicine Department, Faculty of Medicine, Mansoura University, Mansoura, Egypt
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6
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Gibson JT, de Gooyer M, Huang M, Savige J. A systematic review of pathogenic COL4A5 variants and proteinuria in women and girls with X-linked Alport syndrome. Kidney Int Rep 2022; 7:2454-2461. [DOI: 10.1016/j.ekir.2022.08.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/20/2022] [Accepted: 08/22/2022] [Indexed: 11/17/2022] Open
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Savige J. Heterozygous pathogenic COL4A3 or COL4A4 variants (AD Alport syndrome) is common, and not typically associated with end-stage kidney failure, hearing loss or ocular abnormalities. Kidney Int Rep 2022; 7:1933-1938. [PMID: 36090501 PMCID: PMC9458992 DOI: 10.1016/j.ekir.2022.06.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 05/03/2022] [Accepted: 06/01/2022] [Indexed: 12/03/2022] Open
Abstract
The term “autosomal dominant (AD) Alport syndrome” is often used to describe the condition associated with heterozygous pathogenic COL4A3 or COL4A4 variants and has largely replaced “thin basement membrane nephropathy (TBMN).” AD Alport syndrome implies that affected individuals develop end-stage kidney failure (ESKF) as well as the typical Alport hearing loss and ocular abnormalities, but these features have been considered rare with TBMN. Recent studies suggest that ESKF occurs in 14% to 30% of those with heterozygous pathogenic COL4A3 or COL4A4 variants but confirm that the hearing loss and ocular defects occur uncommonly if at all. Uncertainty over the risk of ESKF has persisted. However all the cited studies of heterozygous pathogenic COL4A3 or COL4A4 variants and kidney failure are from hospital-based patients and thus biased toward more severe disease. Multiple unselected cohorts with ESKF have found heterozygous pathogenic variants in COL4A3 and COL4A4 occur about as often as COL4A5 variants, which suggests that AD Alport syndrome causes ESKF as often as X-linked (XL) disease. In the normal population, heterozygous pathogenic COL4A3 and COL4A4 variants are present 20 times more often than COL4A5 variants. Therefore, AD Alport syndrome is complicated by ESKF 20 times less often than XL disease and occurs in fewer than 3% of those with pathogenic COL4A3 or COL4A4 variants by the age of 60. Nevertheless, individuals with heterozygous pathogenic COL4A3 or COL4A4 variants referred to a hospital are still more likely to develop impaired kidney function than those who remain at home undiagnosed.
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Savige J, Huang M, Croos Dabrera MS, Shukla K, Gibson J. Genotype-Phenotype Correlations for Pathogenic COL4A3–COL4A5 Variants in X-Linked, Autosomal Recessive, and Autosomal Dominant Alport Syndrome. Front Med (Lausanne) 2022; 9:865034. [PMID: 35602506 PMCID: PMC9120524 DOI: 10.3389/fmed.2022.865034] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 03/24/2022] [Indexed: 12/28/2022] Open
Abstract
Alport syndrome is inherited as an X-linked (XL), autosomal recessive (AR), or autosomal dominant (AD) disease, where pathogenic COL4A3 – COL4A5 variants affect the basement membrane collagen IV α3α4α5 network. About 50% of pathogenic variants in each gene (major rearrangements and large deletions in 15%, truncating variants in 20%, splicing changes in 15%) are associated with “severe” disease with earlier onset kidney failure, and hearing loss and ocular abnormalities in males with XL inheritance and in males and females with AR disease. Severe variants are also associated with early proteinuria which is itself a risk factor for kidney failure. The other half of pathogenic variants are missense changes which are mainly Gly substitutions. These are generally associated with later onset kidney failure, hearing loss, and less often with major ocular abnormalities. Further determinants of severity for missense variants for XL disease in males, and in AD disease, include Gly versus non-Gly substitutions; increased distance from a non-collagenous interruption or terminus; and Gly substitutions with a more (Arg, Glu, Asp, Val, and Trp) or less disruptive (Ala, Ser, and Cys) residue. Understanding genotype-phenotype correlations in Alport syndrome is important because they help predict the likely age at kidney failure, and the need for early and aggressive management with renin-angiotensin system blockade and other therapies. Genotype-phenotype correlations also help standardize patients with Alport syndrome undergoing trials of clinical treatment. It is unclear whether severe variants predispose more often to kidney cysts or coincidental IgA glomerulonephritis which are recognized increasingly in COL4A3-, COL4A4 - and COL4A5-associated disease.
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Savige J, Mack H, Thomas R, Langsford D, Pianta T. Alport Syndrome With Kidney Cysts Is Still Alport Syndrome. Kidney Int Rep 2022; 7:339-342. [PMID: 35155874 PMCID: PMC8820981 DOI: 10.1016/j.ekir.2021.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 10/28/2021] [Accepted: 11/01/2021] [Indexed: 11/27/2022] Open
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10
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Savige J, Lipska-Zietkiewicz BS, Watson E, Hertz JM, Deltas C, Mari F, Hilbert P, Plevova P, Byers P, Cerkauskaite A, Gregory M, Cerkauskiene R, Ljubanovic DG, Becherucci F, Errichiello C, Massella L, Aiello V, Lennon R, Hopkinson L, Koziell A, Lungu A, Rothe HM, Hoefele J, Zacchia M, Martic TN, Gupta A, van Eerde A, Gear S, Landini S, Palazzo V, al-Rabadi L, Claes K, Corveleyn A, Van Hoof E, van Geel M, Williams M, Ashton E, Belge H, Ars E, Bierzynska A, Gangemi C, Renieri A, Storey H, Flinter F. Guidelines for Genetic Testing and Management of Alport Syndrome. Clin J Am Soc Nephrol 2022; 17:143-154. [PMID: 34930753 PMCID: PMC8763160 DOI: 10.2215/cjn.04230321] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Genetic testing for pathogenic COL4A3-5 variants is usually undertaken to investigate the cause of persistent hematuria, especially with a family history of hematuria or kidney function impairment. Alport syndrome experts now advocate genetic testing for persistent hematuria, even when a heterozygous pathogenic COL4A3 or COL4A4 is suspected, and cascade testing of their first-degree family members because of their risk of impaired kidney function. The experts recommend too that COL4A3 or COL4A4 heterozygotes do not act as kidney donors. Testing for variants in the COL4A3-COL4A5 genes should also be performed for persistent proteinuria and steroid-resistant nephrotic syndrome due to suspected inherited FSGS and for familial IgA glomerulonephritis and kidney failure of unknown cause.
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Affiliation(s)
- Judy Savige
- Department of Medicine (Melbourne Health and Northern Health), The University of Melbourne, Parkville, Victoria, Australia
| | | | - Elizabeth Watson
- South West Genetic Laboratory Hub, North Bristol Trust, Bristol, United Kingdom
| | - Jens Michael Hertz
- Department of Clinical Genetics, Odense University Hospital, Odense, Denmark
| | - Constantinos Deltas
- Center of Excellence in Biobanking and Biomedical Research, University of Cyprus Medical School, Nicosia, Cyprus
| | - Francesca Mari
- Department of Medical Biotechnology, Medical Genetics, University of Siena, Siena, Italy
| | - Pascale Hilbert
- Departement de Biologie Moleculaire, Institute de Pathologie et de Genetique, Gosselies, Belgium
| | - Pavlina Plevova
- Department of Medical Genetics, University Hospital of Ostrava, Ostrava, Czech Republic
- Department of Biomedical Sciences, University Hospital of Ostrava, Ostrava, Czech Republic
| | - Peter Byers
- Department of Pathology, University of Washington, Seattle, Washington
- Department of Medicine (Medical Genetics), University of Washington, Seattle, Washington
| | - Agne Cerkauskaite
- Institute of Biomedical Sciences, Faculty of Medicine, Vilnius University, Vilnius, Lithuania
| | - Martin Gregory
- Division of Nephrology, Department of Medicine, University of Utah Health, Salt Lake City, Utah
| | - Rimante Cerkauskiene
- Clinic of Pediatrics, Institute of Clinical Medicine, Faculty of Medicine, Vilnius University, Vilnius, Lithuania
| | - Danica Galesic Ljubanovic
- Department of Pathology, University of Zagreb, School of Medicine, Dubrava University Hospital, Zagreb, Croatia
| | | | | | - Laura Massella
- Division of Nephrology and Dialysis, Bambino Gesù Children's Hospital, Rome, Italy
| | - Valeria Aiello
- Department of Experimental Diagnostic and Specialty Medicine, Nephrology, Dialysis and Renal Transplant Unit, S. Orsola Hospital, University of Bologna, Bologna, Italy
| | - Rachel Lennon
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Louise Hopkinson
- Wellcome Centre for Cell-Matrix Research, Division of Cell-Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Ania Koziell
- School of Immunology and Microbial Sciences, Faculty of Life Sciences, King's College London, London, United Kingdom
| | - Adrian Lungu
- Pediatric Nephrology Department, Fundeni Clinical Institute, Bucharest, Romania
| | | | - Julia Hoefele
- Institute of Human Genetics, Technical University of Munich, Munich, Germany
| | | | | | - Asheeta Gupta
- Birmingham Children’s Hospital, Birmingham, United Kingdom
| | | | | | - Samuela Landini
- Medical Genetics Unit, Department of Clinical and Experimental Biomedical Sciences “Mario Serio,” University of Florence, Florence, Italy
| | - Viviana Palazzo
- Medical Genetics Unit, Meyer Children's University Hospital, Florence, Italy
| | - Laith al-Rabadi
- Health Sciences Centre, University of Utah, Salt Lake City, Utah
| | - Kathleen Claes
- Department of Nephrology and Renal Transplantation, University Hospitals Leuven, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Anniek Corveleyn
- Center for Human Genetics, University Hospitals and Katholieke Universiteit Leuven, Leuven, Belgium
| | - Evelien Van Hoof
- Center for Human Genetics, University Hospitals and Katholieke Universiteit Leuven, Leuven, Belgium
| | - Micheel van Geel
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Maggie Williams
- Bristol Genetics Laboratory Pathology Sciences, Southmead Hospital, Southmead, United Kingdom
| | - Emma Ashton
- North East Thames Regional Genetics Laboratory, Great Ormond Street Hospital, London, United Kingdom
| | - Hendica Belge
- Institut de Pathologie et de Génétique, Center for Human Genetics, Gosselies, Belgium
| | - Elisabet Ars
- Molecular Biology Laboratory, Fundacio Puigvert, Instituto de Investigaciones Biomédicas Sant Pau, Universitat Autonoma de Barcelona, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Agnieszka Bierzynska
- Bristol Renal Unit, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Concetta Gangemi
- Division of Nephrology and Dialysis, University Hospital of Verona, Verona, Italy
| | - Alessandra Renieri
- Department of Medical Biotechnology, Medical Genetics, University of Siena, Siena, Italy
| | - Helen Storey
- Molecular Genetics, Viapath Laboratories, Guy’s Hospital, London, United Kingdom
| | - Frances Flinter
- Department of Clinical Genetics, Guy’s and St. Thomas’ National Health Service Foundation Trust, London, United Kingdom
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11
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Savige J, Harraka P. Pathogenic LAMA5 Variants and Kidney Disease. KIDNEY360 2021; 2:1876-1879. [PMID: 35419542 PMCID: PMC8986053 DOI: 10.34067/kid.0007312021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 11/22/2021] [Indexed: 02/04/2023]
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12
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Gibson J, Fieldhouse R, Chan MM, Sadeghi-Alavijeh O, Burnett L, Izzi V, Persikov AV, Gale DP, Storey H, Savige J. Prevalence Estimates of Predicted Pathogenic COL4A3-COL4A5 Variants in a Population Sequencing Database and Their Implications for Alport Syndrome. J Am Soc Nephrol 2021; 32:2273-2290. [PMID: 34400539 PMCID: PMC8729840 DOI: 10.1681/asn.2020071065] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 05/05/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The reported prevalence of Alport syndrome varies from one in 5000 to one in 53,000 individuals. This study estimated the frequencies of predicted pathogenic COL4A3-COL4A5 variants in sequencing databases of populations without known kidney disease. METHODS Predicted pathogenic variants were identified using filtering steps based on the ACMG/AMP criteria, which considered collagen IV α3-α5 position 1 Gly to be critical domains. The population frequencies of predicted pathogenic COL4A3-COL4A5 variants were then determined per mean number of sequenced alleles. Population frequencies for compound heterozygous and digenic combinations were calculated from the results for heterozygous variants. RESULTS COL4A3-COL4A5 variants resulting in position 1 Gly substitutions were confirmed to be associated with hematuria (for each, P<0.001). Predicted pathogenic COL4A5 variants were found in at least one in 2320 individuals. p.(Gly624Asp) represented nearly half (16 of 33, 48%) of the variants in Europeans. Most COL4A5 variants (54 of 59, 92%) had a biochemical feature that potentially mitigated the clinical effect. The predicted pathogenic heterozygous COL4A3 and COL4A4 variants affected one in 106 of the population, consistent with the finding of thin basement membrane nephropathy in normal donor kidney biopsy specimens. Predicted pathogenic compound heterozygous variants occurred in one in 88,866 individuals, and digenic variants in at least one in 44,793. CONCLUSIONS The population frequencies for Alport syndrome are suggested by the frequencies of predicted pathogenic COL4A3-COL4A5 variants, but must be adjusted for the disease penetrance of individual variants and for the likelihood of already diagnosed disease and non-Gly substitutions. Disease penetrance may depend on other genetic and environmental factors.
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Affiliation(s)
- Joel Gibson
- The University of Melbourne Department of Medicine, Melbourne Health and Northern Health, Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Rachel Fieldhouse
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Melanie M.Y. Chan
- Department of Renal Medicine, University College London, London, United Kingdom,Genomics England, Queen Mary University of London, London, United Kingdom
| | - Omid Sadeghi-Alavijeh
- Department of Renal Medicine, University College London, London, United Kingdom,Genomics England, Queen Mary University of London, London, United Kingdom
| | - Leslie Burnett
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Valerio Izzi
- Center for Cell-Matrix Research and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Anton V. Persikov
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey
| | - Daniel P. Gale
- Department of Renal Medicine, University College London, London, United Kingdom,Genomics England, Queen Mary University of London, London, United Kingdom
| | - Helen Storey
- Molecular Genetics, Viapath Laboratories, Guy’s Hospital, London, United Kingdom
| | - Judy Savige
- The University of Melbourne Department of Medicine, Melbourne Health and Northern Health, Royal Melbourne Hospital, Parkville, Victoria, Australia
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13
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Savige J, Harraka P. Pathogenic Variants in the Genes Affected in Alport Syndrome (COL4A3-COL4A5) and Their Association With Other Kidney Conditions: A Review. Am J Kidney Dis 2021; 78:857-864. [PMID: 34245817 DOI: 10.1053/j.ajkd.2021.04.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 04/23/2021] [Indexed: 01/15/2023]
Abstract
Massively Parallel Sequencing identifies pathogenic variants in the genes affected in Alport syndrome (COL4A3 - COL4A5) in up to 30 % of individuals with focal and segmental glomerulosclerosis (FSGS), 10 % of those with kidney failure of unknown cause and 20 % with familial IgA glomerulonephritis. FSGS associated with COL4A3 - COL4A5 variants is usually present by kidney failure onset and may develop because the abnormal glomerular membranes result in podocyte loss and secondary hyperfiltration. The association of COL4A3 - COL4A5 variants with kidney failure or IgA glomerulonephritis may be coincidental and not pathogenic. However, since some of these variants occur more often than they should by chance, some may be pathogenic. COL4A3 - COL4A5 variants are sometimes also found in cystic kidney diseases after autosomal dominant polycystic kidney disease (ADPKD) has been excluded. COL4A3 - COL4A5 variants should be suspected in individuals with FSGS, kidney failure of unknown cause, or familial IgA glomerulonephritis, especially where there is persistent haematuria, and a family history of haematuria or kidney failure.
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Affiliation(s)
- Judy Savige
- The University of Melbourne Department of Medicine, Melbourne Health and Northern Health, Royal Melbourne Hospital, Parkville VIC 3050 AUSTRALIA.
| | - Philip Harraka
- The University of Melbourne Department of Medicine, Melbourne Health and Northern Health, Royal Melbourne Hospital, Parkville VIC 3050 AUSTRALIA
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14
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Sharma S, Smyth B. From Proteinuria to Fibrosis: An Update on Pathophysiology and Treatment Options. Kidney Blood Press Res 2021; 46:411-420. [PMID: 34130301 DOI: 10.1159/000516911] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 04/28/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Proteinuria is a key biomarker in nephrology. It is central to diagnosis and risk assessment and the primary target of many important therapies. Etiologies resulting in pathological proteinuria include congenital and acquired disorders, as well as both glomerular (immune/non-immune mediated) and tubular defects. SUMMARY Untreated proteinuria is strongly linked to progressive loss of kidney function and kidney failure. Excess protein reaching the renal tubules is ordinarily resorbed by the tubular epithelium. However, when these mechanisms are overwhelmed, a variety of inflammatory and fibrotic pathways are activated, causing both interstitial fibrosis and glomerulosclerosis. Nevertheless, the specific mechanisms underlying this are complex and remain incompletely understood. Recently, a number of treatments, in addition to angiotensin system blockade, have been shown to effectively slow the progression of proteinuric chronic kidney disease. However, additional therapies are clearly needed. Key message: This review provides an update on the pathophysiology of proteinuria, the pathways leading to fibrosis, and an overview of current and emerging therapies.
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Affiliation(s)
- Sonia Sharma
- Department of Pediatric Nephrology, Fortis Hospital, Shalimar-Bagh, New Delhi, India
| | - Brendan Smyth
- Department of Renal Medicine, St. George Hospital, Sydney, New South Wales, Australia
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15
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Ning L, Suleiman HY, Miner JH. Synaptopodin deficiency exacerbates kidney disease in a mouse model of Alport syndrome. Am J Physiol Renal Physiol 2021; 321:F12-F25. [PMID: 34029143 DOI: 10.1152/ajprenal.00035.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Synaptopodin (Synpo) is an actin-associated protein in podocyte foot processes. By generating mice that completely lack Synpo, we previously showed that Synpo is dispensable for normal kidney function. However, lack of Synpo worsened adriamycin-induced nephropathy, indicating a protective role for Synpo in injured podocytes. Here, we investigated whether lack of Synpo directly impacts a genetic disease, Alport syndrome (AS), because Synpo is reduced in podocytes of affected humans and mice; whether this is merely an association or pathogenic is unknown. We used collagen type IV-α5 (Col4a5) mutant mice, which model X-linked AS, showing glomerular basement membrane (GBM) abnormalities, eventual foot process effacement, and progression to end-stage kidney disease. We intercrossed mice carrying mutations in Synpo and Col4a5 to produce double-mutant mice. Urine and tissue were taken at select time points to evaluate albuminuria, histopathology, and glomerular capillary wall composition and ultrastructure. Lack of Synpo in Col4a5-/Y, Col4a5-/-, or Col4a5+/- Alport mice led to the acceleration of disease progression, including more severe proteinuria and glomerulosclerosis. Absence of Synpo attenuated the shift of myosin IIA from the podocyte cell body and major processes to actin cables near the GBM in the areas of effacement. We speculate that this is mechanistically associated with enhanced loss of podocytes due to easier detachment from the GBM. We conclude that Synpo deletion exacerbates the disease phenotype in Alport mice, revealing the podocyte actin cytoskeleton as a target for therapy in patients with AS.NEW & NOTEWORTHY Alport syndrome (AS) is a hereditary disease of the glomerular basement with hematuria and proteinuria. Podocytes eventually exhibit foot process effacement, indicating actin cytoskeletal changes. To investigate how cytoskeletal changes impact podocytes, we generated Alport mice lacking synaptopodin, an actin-binding protein in foot processes. Analysis showed a more rapid disease progression, demonstrating that synaptopodin is protective. This suggests that the actin cytoskeleton is a target for therapy in AS and perhaps other glomerular diseases.
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Affiliation(s)
- Liang Ning
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Hani Y Suleiman
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Jeffrey H Miner
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
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16
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Iampietro C, Bellucci L, Arcolino FO, Arigoni M, Alessandri L, Gomez Y, Papadimitriou E, Calogero RA, Cocchi E, Van Den Heuvel L, Levtchenko E, Bussolati B. Molecular and functional characterization of urine-derived podocytes from patients with Alport syndrome. J Pathol 2021; 252:88-100. [PMID: 32652570 PMCID: PMC7589231 DOI: 10.1002/path.5496] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 05/25/2020] [Accepted: 06/22/2020] [Indexed: 12/12/2022]
Abstract
Alport syndrome (AS) is a genetic disorder involving mutations in the genes encoding collagen IV α3, α4 or α5 chains, resulting in the impairment of glomerular basement membrane. Podocytes are responsible for production and correct assembly of collagen IV isoforms; however, data on the phenotypic characteristics of human AS podocytes and their functional alterations are currently limited. The evident loss of viable podocytes into the urine of patients with active glomerular disease enables their isolation in a non‐invasive way. Here we isolated, immortalized, and subcloned podocytes from the urine of three different AS patients for molecular and functional characterization. AS podocytes expressed a typical podocyte signature and showed a collagen IV profile reflecting each patient's mutation. Furthermore, RNA‐sequencing analysis revealed 348 genes differentially expressed in AS podocytes compared with control podocytes. Gene Ontology analysis underlined the enrichment in genes involved in cell motility, adhesion, survival, and angiogenesis. In parallel, AS podocytes displayed reduced motility. Finally, a functional permeability assay, using a podocyte–glomerular endothelial cell co‐culture system, was established and AS podocyte co‐cultures showed a significantly higher permeability of albumin compared to control podocyte co‐cultures, in both static and dynamic conditions under continuous perfusion. In conclusion, our data provide a molecular characterization of immortalized AS podocytes, highlighting alterations in several biological processes related to extracellular matrix remodelling. Moreover, we have established an in vitro model to reproduce the altered podocyte permeability observed in patients with AS. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland..
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Affiliation(s)
- Corinne Iampietro
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Linda Bellucci
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Fanny O Arcolino
- Laboratory of Pediatric Nephrology, Department of Development & Regeneration, University of Leuven, Leuven, Belgium
| | - Maddalena Arigoni
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Luca Alessandri
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Yonathan Gomez
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Elli Papadimitriou
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Raffaele A Calogero
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Enrico Cocchi
- Department of Pediatric Nephrology, University of Torino, Torino, Italy.,Division of Nephrology and Center for Precision Medicine and Genomics, Department of Medicine, Columbia University, New York, NY, USA
| | - Lambertus Van Den Heuvel
- Laboratory of Pediatric Nephrology, Department of Development & Regeneration, University of Leuven, Leuven, Belgium
| | - Elena Levtchenko
- Laboratory of Pediatric Nephrology, Department of Development & Regeneration, University of Leuven, Leuven, Belgium.,Department of Pediatric Nephrology, University Hospitals Leuven, Leuven, Belgium
| | - Benedetta Bussolati
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
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17
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Bidirectional, non-necrotizing glomerular crescents are the critical pathology in X-linked Alport syndrome mouse model harboring nonsense mutation of human COL4A5. Sci Rep 2020; 10:18891. [PMID: 33144651 PMCID: PMC7642296 DOI: 10.1038/s41598-020-76068-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 10/23/2020] [Indexed: 12/11/2022] Open
Abstract
X-linked Alport syndrome (XLAS) is a progressive kidney disease caused by genetic abnormalities of COL4A5. Lack of collagen IV α5 chain staining and “basket-weave” by electron microscopy (EM) in glomerular basement membrane (GBM) are its typical pathology. However, the causal relationship between GBM defects and progressive nephropathy is unknown. We analyzed sequential pathology in a mouse model of XLAS harboring a human nonsense mutation of COL4A5. In mutant mice, nephropathy commenced from focal GBM irregularity by EM at 6 weeks of age, prior to exclusive crescents at 13 weeks of age. Low-vacuum scanning EM demonstrated substantial ragged features in GBM, and crescents were closely associated with fibrinoid exudate, despite lack of GBM break and podocyte depletion at 13 weeks of age. Crescents were derived from two sites by different cellular components. One was CD44 + cells, often with fibrinoid exudate in the urinary space, and the other was accumulation of α-SMA + cells in the thickened Bowman’s capsule. These changes finally coalesced, leading to global obliteration. In conclusion, vulnerability of glomerular and capsular barriers to the structural defect in collagen IV may cause non-necrotizing crescents via activation of PECs and migration of interstitial fibroblasts, promoting kidney disease in this model.
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18
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Urinary podocyte mRNAs precede microalbuminuria as a progression risk marker in human type 2 diabetic nephropathy. Sci Rep 2020; 10:18209. [PMID: 33097787 PMCID: PMC7584595 DOI: 10.1038/s41598-020-75320-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 10/08/2020] [Indexed: 02/07/2023] Open
Abstract
Earlier detection of progression risk in diabetic nephropathy will allow earlier intervention to reduce progression. The hypothesis that urinary pellet podocyte mRNA is a more sensitive progression risk marker than microalbuminuria was tested. A cross sectional cohort of 165 type 2 diabetics and 41 age and sex-matched controls were enrolled. Podocyte stress (Urinary pellet podocin:nephrin mRNA ratio), podocyte detachment (Urinary pellet podocin mRNA:creatinine ratio: UPPod:CR) and a tubular marker (Urinary pellet aquaporin 2:creatinine ratio) were measured in macro-albuminuric, micro-albuminuric and norm-albuminuric groups. eGFR was reassessed after 4 years in 124 available diabetic subjects. Urinary pellet podocyte and tubular mRNA markers were increased in all diabetic groups in cross-sectional analysis. After 4 years of follow-up univariable and multivariate model analysis showed that the only urinary markers significantly related to eGFR slope were UPPod:CR (P < 0.01) and albuminuria (P < 0.01). AUC analysis using K-fold cross validation to predict eGFR loss of ≥ 3 ml/min/1.73m2/year showed that UPPod:CR and albuminuria each improved the AUC similarly such that combined with clinical variables they gave an AUC = 0.70. Podocyte markers and albuminuria had overlapping AUC contributions, as expected if podocyte depletion causes albuminuria. In the norm-albuminuria cohort (n = 75) baseline UPPod:CR was associated with development of albuminuria (P = 0.007) and, in the tertile with both normal kidney function (eGFR 84 ± 11.7 ml/min/1.73m2) and norm-albuminuria at baseline, UPPod:CR was associated with eGFR loss rate (P = 0.003). In type 2 diabetics with micro- or macro-albuminuria UPPod:CR and albuminuria were equally good at predicting eGFR loss. For norm-albuminuric type 2 diabetics UPPod:CR predicted both albuminuria and eGFR loss.
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19
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Kaverina NV, Eng DG, Miner JH, Pippin JW, Shankland SJ. Parietal epithelial cell differentiation to a podocyte fate in the aged mouse kidney. Aging (Albany NY) 2020; 12:17601-17624. [PMID: 32858527 PMCID: PMC7521511 DOI: 10.18632/aging.103788] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 06/29/2020] [Indexed: 01/24/2023]
Abstract
Healthy aging is typified by a progressive and absolute loss of podocytes over the lifespan of animals and humans. To test the hypothesis that a subset of glomerular parietal epithelial cell (PEC) progenitors transition to a podocyte fate with aging, dual reporter PEC-rtTA|LC1|tdTomato|Nphs1-FLPo|FRT-EGFP mice were generated. PECs were inducibly labeled with a tdTomato reporter, and podocytes were constitutively labeled with an EGFP reporter. With advancing age (14 and 24 months) glomeruli in the juxta-medullary cortex (JMC) were more severely injured than those in the outer cortex (OC). In aged mice (24m), injured glomeruli with lower podocyte number (41% decrease), showed more PEC migration and differentiation to a podocyte fate than mildly injured or healthy glomeruli. PECs differentiated to a podocyte fate had ultrastructural features of podocytes and co-expressed the podocyte markers podocin, nephrin, p57 and VEGF164, but not markers of mesangial (Perlecan) or endothelial (ERG) cells. PECs differentiated to a podocyte fate did not express CD44, a marker of PEC activation. Taken together, we demonstrate that a subpopulation of PECs differentiate to a podocyte fate predominantly in injured glomeruli in mice of advanced age.
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Affiliation(s)
| | - Diana G. Eng
- Division of Nephrology, University of Washington, Seattle, WA 98195, USA
| | - Jeffrey H. Miner
- Division of Nephrology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Jeffrey W. Pippin
- Division of Nephrology, University of Washington, Seattle, WA 98195, USA
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20
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Demir E, Caliskan Y. Variations of type IV collagen-encoding genes in patients with histological diagnosis of focal segmental glomerulosclerosis. Pediatr Nephrol 2020; 35:927-936. [PMID: 31254113 DOI: 10.1007/s00467-019-04282-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 05/01/2019] [Accepted: 05/31/2019] [Indexed: 01/07/2023]
Abstract
Focal segmental glomerulosclerosis (FSGS), an important cause of end-stage kidney disease (ESKD), covers a spectrum of clinicopathological syndromes sharing a common glomerular lesion, based on an injury of podocytes caused by diverse insults to glomeruli. Although it is well expressed in many reports that the term FSGS is not useful and applicable to a single disease, particularly in genetic studies, FSGS continues to be used as a single clinical diagnosis. Distinguishing genetic forms of FSGS is important for the treatment and overall prognosis because secondary forms of FSGS, produced by rare pathogenic variations in podocyte genes, are not good candidates for immunosuppressive treatment. Over the past decade, several next generation sequencing (NGS) methods have been used to investigate the patients with steroid resistance nephrotic syndrome (SRNS) or FSGS. Pathogenic variants in COL4A3, COL4A4, or COL4A5 genes have been frequently identified in patients with histologic diagnosis of FSGS. The contribution of these mostly heterozygous genetic variations in FSGS pathogenesis and the clinical course of patients with these variations have not been well characterized. This review emphasizes the importance of appropriate approach in selection and diagnosis of cases and interpretation of the genetic data in these studies and suggests a detailed review of existing clinical variant databases using newly available population genetic data.
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Affiliation(s)
- Erol Demir
- Division of Nephrology, Department of Internal Medicine, Istanbul School of Medicine, Istanbul University, Capa, Fatih, 34093, Istanbul, Turkey
| | - Yasar Caliskan
- Division of Nephrology, Department of Internal Medicine, Istanbul School of Medicine, Istanbul University, Capa, Fatih, 34093, Istanbul, Turkey.
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21
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Pisarek-Horowitz A, Fan X, Kumar S, Rasouly HM, Sharma R, Chen H, Coser K, Bluette CT, Hirenallur-Shanthappa D, Anderson SR, Yang H, Beck LH, Bonegio RG, Henderson JM, Berasi SP, Salant DJ, Lu W. Loss of Roundabout Guidance Receptor 2 (Robo2) in Podocytes Protects Adult Mice from Glomerular Injury by Maintaining Podocyte Foot Process Structure. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 190:799-816. [PMID: 32220420 PMCID: PMC7217334 DOI: 10.1016/j.ajpath.2019.12.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 11/24/2019] [Accepted: 12/17/2019] [Indexed: 02/06/2023]
Abstract
Roundabout guidance receptor 2 (ROBO2) plays an important role during early kidney development. ROBO2 is expressed in podocytes, inhibits nephrin-induced actin polymerization, down-regulates nonmuscle myosin IIA activity, and destabilizes kidney podocyte adhesion. However, the role of ROBO2 during kidney injury, particularly in mature podocytes, is not known. Herein, we report that loss of ROBO2 in podocytes [Robo2 conditional knockout (cKO) mouse] is protective from glomerular injuries. Ultrastructural analysis reveals that Robo2 cKO mice display less foot process effacement and better-preserved slit-diaphragm density compared with wild-type littermates injured by either protamine sulfate or nephrotoxic serum (NTS). The Robo2 cKO mice also develop less proteinuria after NTS injury. Further studies reveal that ROBO2 expression in podocytes is up-regulated after glomerular injury because its expression levels are higher in the glomeruli of NTS injured mice and passive Heymann membranous nephropathy rats. Moreover, the amount of ROBO2 in the glomeruli is also elevated in patients with membranous nephropathy. Finally, overexpression of ROBO2 in cultured mouse podocytes compromises cell adhesion. Taken together, these findings suggest that kidney injury increases glomerular ROBO2 expression that might compromise podocyte adhesion and, thus, loss of Robo2 in podocytes could protect from glomerular injury by enhancing podocyte adhesion that helps maintain foot process structure. Our findings also suggest that ROBO2 is a therapeutic target for podocyte injury and podocytopathy.
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Affiliation(s)
- Anna Pisarek-Horowitz
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Xueping Fan
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Sudhir Kumar
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Hila M Rasouly
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Richa Sharma
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Hui Chen
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Kathryn Coser
- Centers for Therapeutic Innovation, Pfizer Inc., Cambridge, Massachusetts
| | | | | | - Sarah R Anderson
- Global Pathology, Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut
| | - Hongying Yang
- Centers for Therapeutic Innovation, Pfizer Inc., Cambridge, Massachusetts
| | - Laurence H Beck
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Ramon G Bonegio
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Joel M Henderson
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Stephen P Berasi
- Centers for Therapeutic Innovation, Pfizer Inc., Cambridge, Massachusetts
| | - David J Salant
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts; Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts
| | - Weining Lu
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts; Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston Medical Center, Boston, Massachusetts.
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22
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Nicklason E, Mack H, Beltz J, Jacob J, Farahani M, Colville D, Savige J. Corneal endothelial cell abnormalities in X-linked Alport syndrome. Ophthalmic Genet 2020; 41:13-19. [PMID: 32159412 DOI: 10.1080/13816810.2019.1709126] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Background: X-linked Alport syndrome results from the effect of COL4A5 mutations on basement membranes in the kidney, ear and eye. This study investigated individuals with X-linked Alport syndrome for corneal abnormalities.Patients and Methods: Six men and four women from 8 families with genetically-diagnosed X-linked Alport syndrome underwent ophthalmological examination including slit lamp examination and corneal endothelial specular microscopy. Results for corneal microscopy for men and women with X-linked disease were compared separately with the mean values for age- matched normals using the student's t test.Results: Five of the 6 men had end-stage kidney failure, all 6 had a hearing loss, three had lenticonus, and three had a central fleck retinopathy. Two men had a history of recurrent corneal erosions but no evidence of posterior polymorphous corneal dystrophy. None of the four women had kidney failure, but two had a hearing loss, and two had a central fleck retinopathy. One woman, whose son had recurrent corneal erosions, also had erosions, but no features of a posterior polymorphous corneal dystrophy.Corneal specular microscopy demonstrated abnormalities in affected men and women, with larger endothelial cells (p = .0001 in men, p = .004 in women) fewer 6-sided cells (p = .0001, p = .001 respectively) and reduced cell density (p = .03, p = .02 respectively) than normal.Conclusions: Recurrent corneal erosions are common in men and women with X-linked Alport syndrome, but posterior polymorphous corneal dystrophy is rare. The abnormal corneal endothelial cells in affected men and women are consistent with an abnormal Descemet membrane, and the reduced cell density resembles the reduced podocyte numbers found in the Alport glomerulus.
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Affiliation(s)
- Eleanor Nicklason
- Department of Medicine (Melbourne Health), The University of Melbourne, Parkville, Australia
| | - Heather Mack
- Department of Surgery (Ophthalmology), The University of Melbourne, Parkville, Australia
| | - Jacqueline Beltz
- Department of Ophthalmology, The University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Julie Jacob
- Department of Ophthalmology, University Hospitals Leuven, Leuven, Belgium
| | - Mina Farahani
- Department of Ophthalmology, University of California, Irvine, California, USA
| | - Deb Colville
- Department of Medicine (Melbourne Health), The University of Melbourne, Parkville, Australia
| | - Judy Savige
- Department of Medicine (Melbourne Health), The University of Melbourne, Parkville, Australia
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23
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Minakawa A, Fukuda A, Sato Y, Kikuchi M, Kitamura K, Wiggins RC, Fujimoto S. Podocyte hypertrophic stress and detachment precedes hyperglycemia or albuminuria in a rat model of obesity and type2 diabetes-associated nephropathy. Sci Rep 2019; 9:18485. [PMID: 31811176 PMCID: PMC6898392 DOI: 10.1038/s41598-019-54692-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 10/16/2019] [Indexed: 02/06/2023] Open
Abstract
Type2 diabetes-associated nephropathy is the commonest cause of renal failure. Mechanisms responsible are controversial. Leptin-deficient hyperphagic Zucker (fa/fa) rats were modeled to test the hypothesis that glomerular enlargement drives podocyte hypertrophic stress leading to accelerated podocyte detachment, podocyte depletion, albuminuria and progression. By 6weeks, prior to development of either hyperglycemia or albuminuria, fa/fa rats were hyperinsulinemic with high urinary IGF1/2 excretion, gaining weight rapidly, and had 1.6-fold greater glomerular volume than controls (P < 0.01). At this time the podocyte number per glomerulus was not yet reduced although podocytes were already hypertrophically stressed as shown by high podocyte phosphor-ribosomal S6 (a marker of mTORC1 activation), high urinary pellet podocin:nephrin mRNA ratio and accelerated podocyte detachment (high urinary pellet podocin:aquaporin2 mRNA ratio). Subsequently, fa/fa rats became both hyperglycemic and albuminuric. 24 hr urine albumin excretion correlated highly with decreasing podocyte density (R2 = 0.86), as a consequence of both increasing glomerular volume (R2 = 0.70) and decreasing podocyte number (R2 = 0.63). Glomerular podocyte loss rate was quantitatively related to podocyte detachment rate measured by urine pellet mRNAs. Glomerulosclerosis occurred when podocyte density reached <50/106um3. Reducing food intake by 40% to slow growth reduced podocyte hypertrophic stress and "froze" all elements of the progression process in place, but had small effect on hyperglycemia. Glomerular enlargement caused by high growth factor milieu starting in pre-diabetic kidneys appears to be a primary driver of albuminuria in fa/fa rats and thereby an under-recognized target for progression prevention. Progression risk could be identified prior to onset of hyperglycemia or albuminuria, and monitored non-invasively by urinary pellet podocyte mRNA markers.
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Affiliation(s)
- Akihiro Minakawa
- Division of Nephrology, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- First Department of Internal Medicine, University of Miyazaki, Miyazaki, Japan
| | - Akihiro Fukuda
- Division of Nephrology, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
- Department of Endocrinology, Metabolism, Rheumatology and Nephrology, Faculty of Medicine, Oita University, Yufu, Japan.
| | - Yuji Sato
- Division of Nephrology, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
| | - Masao Kikuchi
- Division of Nephrology, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- First Department of Internal Medicine, University of Miyazaki, Miyazaki, Japan
| | - Kazuo Kitamura
- First Department of Internal Medicine, University of Miyazaki, Miyazaki, Japan
| | - Roger C Wiggins
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Shouichi Fujimoto
- Division of Nephrology, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
- Department of Hemovascular Medicine and Artificial Organs, University of Miyazaki, Miyazaki, Japan
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24
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Davis J, Tjipto A, Hegerty K, Mallett A. The use of electron microscopy in the diagnosis of focal segmental glomerulosclerosis: are current pathological techniques missing important abnormalities in the glomerular basement membrane? F1000Res 2019; 8:1204. [PMID: 31781368 PMCID: PMC6854873 DOI: 10.12688/f1000research.19997.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/04/2019] [Indexed: 01/15/2023] Open
Abstract
Background: There is an increasing appreciation that variants of the
COL4A genes may be associated with the development of focal segmental glomerulosclerosis (FSGS). On electron microscopy, such variants may produce characteristic changes within the glomerular basement membrane (GBM). These changes may be missed if glomerular lesions histologically diagnosed as FSGS on light microscopy are not subjected to electron microscopy. Methods: We conducted a retrospective cohort analysis of all patients presenting to two hospitals who received a primary histological diagnosis of FSGS to see if these samples underwent subsequent electron microscopy. Each such sample was also scrutinised for the presence of characteristic changes of an underlying type IV collagen disorder Results: A total of 43 patients were identified. Of these, only 30 underwent electron microscopy. In two samples there were histological changes detected that might have suggested the underlying presence of a type IV collagen disorder. Around one in three biopsy samples that had a histological diagnosis of FSGS were not subjected to electron microscopy. Conclusion: Renal biopsy samples that have a histological diagnosis of primary FSGS not subjected to subsequent electron microscopy may potentially miss ultrastructural changes in the GBM that could signify an underlying type IV collagen disorder as the patient’s underlying disease process. This could potentially affect both them and their families’ investigative and management decisions given potential for implications for transplant, heritability and different disease pathogenesis. This represents a gap in care which should be reflected upon and rectified via iterative standard care and unit-level quality assurance initiatives.
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Affiliation(s)
- Justin Davis
- Department of Nephrology, Barwon Health, Geelong, Victoria, 3220, Australia
| | - Alwie Tjipto
- Department of Nephrology, Barwon Health, Geelong, Victoria, 3220, Australia
| | - Katharine Hegerty
- Department of Nephrology, Royal Brisbane and Women's Hospital, Herston, Queensland, Australia
| | - Andrew Mallett
- Department of Nephrology, Royal Brisbane and Women's Hospital, Herston, Queensland, Australia
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25
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Puelles VG, Fleck D, Ortz L, Papadouri S, Strieder T, Böhner AM, van der Wolde JW, Vogt M, Saritas T, Kuppe C, Fuss A, Menzel S, Klinkhammer BM, Müller-Newen G, Heymann F, Decker L, Braun F, Kretz O, Huber TB, Susaki EA, Ueda HR, Boor P, Floege J, Kramann R, Kurts C, Bertram JF, Spehr M, Nikolic-Paterson DJ, Moeller MJ. Novel 3D analysis using optical tissue clearing documents the evolution of murine rapidly progressive glomerulonephritis. Kidney Int 2019; 96:505-516. [DOI: 10.1016/j.kint.2019.02.034] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 01/23/2019] [Accepted: 02/28/2019] [Indexed: 12/17/2022]
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26
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Postnatal podocyte gain: Is the jury still out? Semin Cell Dev Biol 2019; 91:147-152. [DOI: 10.1016/j.semcdb.2018.07.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 06/24/2018] [Accepted: 07/05/2018] [Indexed: 02/06/2023]
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27
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Chiba T, Nihei S, Komatsu H, Obara M, Ishigaki Y, Sasaki A, Kudo K. Deterioration of Glycemic Control Contributes to the Prevalence of Proteinuria among Bevacizumab-Treated Cancer Patients with Type 2 Diabetes Mellitus. Biol Pharm Bull 2018; 41:1722-1726. [PMID: 30381672 DOI: 10.1248/bpb.b18-00493] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The objective of this study was to investigate whether improving glycemic control reduces the prevalence and progression of proteinuria among bevacizumab (BEV)-treated cancer patients with type 2 diabetes mellitus (DM). We retrospectively reviewed the medical records of 55 patients with type 2 DM who were treated with BEV between July 1 2011 and May 31 2018 at Iwate Medical University Hospital. The patients were classified based on changes in glycated hemoglobin (HbA1c) level during the 3 months following BEV administration into the "HbA1c elevated" group (+0.5% or above, n=24) and the "HbA1c non-elevated" group (indicating no change or decrease; n=31). At 3 months following BEV administration, the means of HbA1c and its change rate in the 'HbA1c elevated' group was significantly higher than that in the 'HbA1c non-elevated' group, and the prevalence of proteinuria in the 'HbA1c elevated' group was significantly higher than that in the 'HbA1c non-elevated' group. Additionally, our subjects were classified into the proteinuria group and non-proteinuria group. The mean HbA1c level in the proteinuria group was significantly higher than that in the non-proteinuria group at 3 months following BEV administration. Furthermore, the mean rates of change of HbA1c level in patients experiencing grades 1 and 2 proteinuria were +9.97±2.26 and +14.0±3.82%, respectively. These values were significantly higher than those of patients with no proteinuria (-2.15±1.96%). Our results suggest that deterioration of glycemic control contributes to the prevalence of proteinuria among BEV-treated cancer patients with type 2 DM.
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Affiliation(s)
- Takeshi Chiba
- Division of Clinical Pharmaceutics and Pharmacy Practice, Department of Clinical Pharmacy, School of Pharmacy, Iwate Medical University.,Department of Pharmacy, Iwate Medical University Hospital
| | - Satoru Nihei
- Division of Clinical Pharmaceutics and Pharmacy Practice, Department of Clinical Pharmacy, School of Pharmacy, Iwate Medical University.,Department of Pharmacy, Iwate Medical University Hospital
| | - Hideaki Komatsu
- Department of Surgery, School of Medicine, Iwate Medical University
| | - Mami Obara
- Department of Pharmacy, Iwate Medical University Hospital
| | - Yasushi Ishigaki
- Division of Diabetes and Metabolism, Department of Internal Medicine, School of Medicine, Iwate Medical University
| | - Akira Sasaki
- Division of Diabetes and Metabolism, Department of Internal Medicine, School of Medicine, Iwate Medical University
| | - Kenzo Kudo
- Division of Clinical Pharmaceutics and Pharmacy Practice, Department of Clinical Pharmacy, School of Pharmacy, Iwate Medical University.,Department of Pharmacy, Iwate Medical University Hospital
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28
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Funk SD, Lin MH, Miner JH. Alport syndrome and Pierson syndrome: Diseases of the glomerular basement membrane. Matrix Biol 2018; 71-72:250-261. [PMID: 29673759 PMCID: PMC6146048 DOI: 10.1016/j.matbio.2018.04.008] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 04/13/2018] [Accepted: 04/13/2018] [Indexed: 12/17/2022]
Abstract
The glomerular basement membrane (GBM) is an important component of the kidney's glomerular filtration barrier. Like all basement membranes, the GBM contains type IV collagen, laminin, nidogen, and heparan sulfate proteoglycan. It is flanked by the podocytes and glomerular endothelial cells that both synthesize it and adhere to it. Mutations that affect the GBM's collagen α3α4α5(IV) components cause Alport syndrome (kidney disease with variable ear and eye defects) and its variants, including thin basement membrane nephropathy. Mutations in LAMB2 that impact the synthesis or function of laminin α5β2γ1 (LM-521) cause Pierson syndrome (congenital nephrotic syndrome with eye and neurological defects) and its less severe variants, including isolated congenital nephrotic syndrome. The very different types of kidney diseases that result from mutations in collagen IV vs. laminin are likely due to very different pathogenic mechanisms. A better understanding of these mechanisms should lead to targeted therapeutic approaches that can help people with these rare but important diseases.
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Affiliation(s)
- Steven D Funk
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Meei-Hua Lin
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Jeffrey H Miner
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
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29
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Fukuda A, Minakawa A, Sato Y, Iwakiri T, Iwatsubo S, Komatsu H, Kikuchi M, Kitamura K, Wiggins RC, Fujimoto S. Urinary podocyte and TGF-β1 mRNA as markers for disease activity and progression in anti-glomerular basement membrane nephritis. Nephrol Dial Transplant 2018; 32:1818-1830. [PMID: 28419296 DOI: 10.1093/ndt/gfx047] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 02/03/2017] [Indexed: 12/11/2022] Open
Abstract
Background Podocyte depletion causes glomerulosclerosis, with persistent podocyte loss being a major factor driving disease progression. Urinary podocyte mRNA is potentially useful for monitoring disease progression in both animal models and in humans. To determine whether the same principles apply to crescentic glomerular injury, a rat model of anti-glomerular basement membrane (anti-GBM) nephritis was studied in parallel with a patient with anti-GBM nephritis. Methods Podocyte loss was measured by Wilms' Tumor 1-positive podocyte nuclear counting and density, glomerular epithelial protein 1 or synaptopodin-positive podocyte tuft area and urinary podocyte mRNA excretion rate. Glomerulosclerosis was evaluated by Azan staining and urinary transforming growth factor (TGF)-β1 mRNA excretion rate. Results In the rat model, sequential kidney biopsies revealed that after a threshold of 30% podocyte loss, the degree of glomerulosclerosis was linearly associated with the degree of podocyte depletion, compatible with podocyte depletion driving the sclerotic process. Urinary podocyte mRNA correlated with the rate of glomerular podocyte loss. In treatment studies, steroids prevented glomerulosclerosis in the anti-GBM model in contrast to angiotensin II inhibition, which lacked a protective effect, and urinary podocyte and TGF-β1 mRNA markers more accurately reflected both the amount of podocyte depletion and the degree of glomerulosclerosis compared with proteinuria under both scenarios. In a patient successfully treated for anti-GBM nephritis, urinary podocyte and TGB-β1 mRNA reflected treatment efficacy. Conclusion These results emphasize the role of podocyte depletion in anti-GBM nephritis and suggest that urinary podocyte and TGF-β1 mRNA could serve as markers of disease progression and treatment efficacy.
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Affiliation(s)
- Akihiro Fukuda
- First Department of Internal Medicine, University of Miyazaki, Miyazaki, Japan
| | - Akihiro Minakawa
- First Department of Internal Medicine, University of Miyazaki, Miyazaki, Japan
| | - Yuji Sato
- First Department of Internal Medicine, University of Miyazaki, Miyazaki, Japan
| | - Takashi Iwakiri
- First Department of Internal Medicine, University of Miyazaki, Miyazaki, Japan
| | - Shuji Iwatsubo
- First Department of Internal Medicine, University of Miyazaki, Miyazaki, Japan
| | - Hiroyuki Komatsu
- First Department of Internal Medicine, University of Miyazaki, Miyazaki, Japan
| | - Masao Kikuchi
- First Department of Internal Medicine, University of Miyazaki, Miyazaki, Japan
| | - Kazuo Kitamura
- First Department of Internal Medicine, University of Miyazaki, Miyazaki, Japan
| | - Roger C Wiggins
- Department of Internal Medicine, Division of Nephrology, University of Michigan, Ann Arbor, MI, USA
| | - Shouichi Fujimoto
- First Department of Internal Medicine, University of Miyazaki, Miyazaki, Japan.,Department of Hemovascular Medicine and Artificial Organs, University of Miyazaki, Miyazaki, Japan
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30
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Ding F, Wickman L, Wang SQ, Zhang Y, Wang F, Afshinnia F, Hodgin J, Ding J, Wiggins RC. Accelerated podocyte detachment and progressive podocyte loss from glomeruli with age in Alport Syndrome. Kidney Int 2017; 92:1515-1525. [PMID: 28754557 PMCID: PMC5696060 DOI: 10.1016/j.kint.2017.05.017] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 04/12/2017] [Accepted: 05/04/2017] [Indexed: 01/15/2023]
Abstract
Podocyte depletion is a common mechanism driving progression in glomerular diseases. Alport Syndrome glomerulopathy, caused by defective α3α4α5 (IV) collagen heterotrimer production by podocytes, is associated with an increased rate of podocyte detachment detectable in urine and reduced glomerular podocyte number suggesting that defective podocyte adherence to the glomerular basement membrane might play a role in driving progression. Here a genetically phenotyped Alport Syndrome cohort of 95 individuals [urine study] and 41 archived biopsies [biopsy study] were used to test this hypothesis. Podocyte detachment rate (measured by podocin mRNA in urine pellets expressed either per creatinine or 24-hour excretion) was significantly increased 11-fold above control, and prior to a detectably increased proteinuria or microalbuminuria. In parallel, Alport Syndrome glomeruli lose an average 26 podocytes per year versus control glomeruli that lose 2.3 podocytes per year, an 11-fold difference corresponding to the increased urine podocyte detachment rate. Podocyte number per glomerulus in Alport Syndrome biopsies is projected to be normal at birth (558/glomerulus) but accelerated podocyte loss was projected to cause end-stage kidney disease by about 22 years. Biopsy data from two independent cohorts showed a similar estimated glomerular podocyte loss rate comparable to the measured 11-fold increase in podocyte detachment rate. Reduction in podocyte number and density in biopsies correlated with proteinuria, glomerulosclerosis, and reduced renal function. Thus, the podocyte detachment rate appears to be increased from birth in Alport Syndrome, drives the progression process, and could potentially help predict time to end-stage kidney disease and response to treatment.
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Affiliation(s)
- Fangrui Ding
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Larysa Wickman
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, USA
| | - Su Q Wang
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Yanqin Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Fang Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Farsad Afshinnia
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Jeffrey Hodgin
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jie Ding
- Department of Pediatrics, Peking University First Hospital, Beijing, China.
| | - Roger C Wiggins
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA.
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31
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Tsuji K, Suleiman H, Miner JH, Daley JM, Capen DE, Păunescu TG, Lu HAJ. Ultrastructural Characterization of the Glomerulopathy in Alport Mice by Helium Ion Scanning Microscopy (HIM). Sci Rep 2017; 7:11696. [PMID: 28916834 PMCID: PMC5601433 DOI: 10.1038/s41598-017-12064-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 09/01/2017] [Indexed: 01/19/2023] Open
Abstract
The glomerulus exercises its filtration barrier function by establishing a complex filtration apparatus consisting of podocyte foot processes, glomerular basement membrane and endothelial cells. Disruption of any component of the glomerular filtration barrier leads to glomerular dysfunction, frequently manifested as proteinuria. Ultrastructural studies of the glomerulus by transmission electron microscopy (TEM) and conventional scanning electron microscopy (SEM) have been routinely used to identify and classify various glomerular diseases. Here we report the application of newly developed helium ion scanning microscopy (HIM) to examine the glomerulopathy in a Col4a3 mutant/Alport syndrome mouse model. Our study revealed unprecedented details of glomerular abnormalities in Col4a3 mutants including distorted podocyte cell bodies and disorganized primary processes. Strikingly, we observed abundant filamentous microprojections arising from podocyte cell bodies and processes, and presence of unique bridging processes that connect the primary processes and foot processes in Alport mice. Furthermore, we detected an altered glomerular endothelium with disrupted sub-endothelial integrity. More importantly, we were able to clearly visualize the complex, three-dimensional podocyte and endothelial interface by HIM. Our study demonstrates that HIM provides nanometer resolution to uncover and rediscover critical ultrastructural characteristics of the glomerulopathy in Col4a3 mutant mice.
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Affiliation(s)
- Kenji Tsuji
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Department of Medicine, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA
| | - Hani Suleiman
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA.,Division of Nephrology, Washington University School of Medicine, St. Louis, MO, USA
| | - Jeffrey H Miner
- Division of Nephrology, Washington University School of Medicine, St. Louis, MO, USA
| | - James M Daley
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Diane E Capen
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Department of Medicine, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA
| | - Teodor G Păunescu
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Department of Medicine, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA
| | - Hua A Jenny Lu
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Department of Medicine, Massachusetts General Hospital, and Harvard Medical School, Boston, MA, USA.
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32
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Mallett AJ, McCarthy HJ, Ho G, Holman K, Farnsworth E, Patel C, Fletcher JT, Mallawaarachchi A, Quinlan C, Bennetts B, Alexander SI. Massively parallel sequencing and targeted exomes in familial kidney disease can diagnose underlying genetic disorders. Kidney Int 2017; 92:1493-1506. [PMID: 28844315 DOI: 10.1016/j.kint.2017.06.013] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 06/06/2017] [Accepted: 06/08/2017] [Indexed: 10/19/2022]
Abstract
Inherited kidney disease encompasses a broad range of disorders, with both multiple genes contributing to specific phenotypes and single gene defects having multiple clinical presentations. Advances in sequencing capacity may allow a genetic diagnosis for familial renal disease, by testing the increasing number of known causative genes. However, there has been limited translation of research findings of causative genes into clinical settings. Here, we report the results of a national accredited diagnostic genetic service for familial renal disease. An expert multidisciplinary team developed a targeted exomic sequencing approach with ten curated multigene panels (207 genes) and variant assessment individualized to the patient's phenotype. A genetic diagnosis (pathogenic genetic variant[s]) was identified in 58 of 135 families referred in two years. The genetic diagnosis rate was similar between families with a pediatric versus adult proband (46% vs 40%), although significant differences were found in certain panels such as atypical hemolytic uremic syndrome (88% vs 17%). High diagnostic rates were found for Alport syndrome (22 of 27) and tubular disorders (8 of 10), whereas the monogenic diagnostic rate for congenital anomalies of the kidney and urinary tract was one of 13. Quality reporting was aided by a strong clinical renal and genetic multidisciplinary committee review. Importantly, for a diagnostic service, few variants of uncertain significance were found with this targeted, phenotype-based approach. Thus, use of targeted massively parallel sequencing approaches in inherited kidney disease has a significant capacity to diagnose the underlying genetic disorder across most renal phenotypes.
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Affiliation(s)
- Andrew J Mallett
- Kidney Health Service and Conjoint Renal Research Laboratory, Royal Brisbane and Women's Hospital, Brisbane, Australia; Faculty of Medicine, University of Queensland, Brisbane, Australia; KidGen Renal Genetics Flagship, Australian Genomics Health Alliance, Australia.
| | - Hugh J McCarthy
- KidGen Renal Genetics Flagship, Australian Genomics Health Alliance, Australia; Department of Pediatric Nephrology, The Children's Hospital at Westmead, Sydney, Australia; Discipline of Pediatrics and Child Health, University of Sydney, Sydney, Australia
| | - Gladys Ho
- KidGen Renal Genetics Flagship, Australian Genomics Health Alliance, Australia; Department of Molecular Genetics, The Children's Hospital at Westmead, Sydney, Australia
| | - Katherine Holman
- KidGen Renal Genetics Flagship, Australian Genomics Health Alliance, Australia; Department of Molecular Genetics, The Children's Hospital at Westmead, Sydney, Australia
| | - Elizabeth Farnsworth
- KidGen Renal Genetics Flagship, Australian Genomics Health Alliance, Australia; Department of Molecular Genetics, The Children's Hospital at Westmead, Sydney, Australia
| | - Chirag Patel
- KidGen Renal Genetics Flagship, Australian Genomics Health Alliance, Australia; Genetic Health Queensland, Royal Brisbane and Women's Hospital, Brisbane, Australia
| | - Jeffery T Fletcher
- KidGen Renal Genetics Flagship, Australian Genomics Health Alliance, Australia; Department of Pediatrics, The Canberra Hospital, Canberra, Australia
| | - Amali Mallawaarachchi
- KidGen Renal Genetics Flagship, Australian Genomics Health Alliance, Australia; Department of Clinical Genetics, Liverpool Hospital, Sydney, Australia; Discipline of Genetic Medicine, University of Sydney, Sydney, Australia
| | - Catherine Quinlan
- KidGen Renal Genetics Flagship, Australian Genomics Health Alliance, Australia; Murdoch Children's Research Institute, Melbourne, Australia; Department of Pediatric Nephrology, Royal Children's Hospital, Melbourne, Australia
| | - Bruce Bennetts
- KidGen Renal Genetics Flagship, Australian Genomics Health Alliance, Australia; Department of Molecular Genetics, The Children's Hospital at Westmead, Sydney, Australia; Discipline of Genetic Medicine, University of Sydney, Sydney, Australia
| | - Stephen I Alexander
- KidGen Renal Genetics Flagship, Australian Genomics Health Alliance, Australia; Department of Pediatric Nephrology, The Children's Hospital at Westmead, Sydney, Australia; Discipline of Pediatrics and Child Health, University of Sydney, Sydney, Australia; Centre for Kidney Research, University of Sydney, Sydney, Australia.
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33
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Puelles VG, Bertram JF, Moeller MJ. Quantifying podocyte depletion: theoretical and practical considerations. Cell Tissue Res 2017; 369:229-236. [DOI: 10.1007/s00441-017-2630-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/21/2017] [Indexed: 10/19/2022]
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34
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Podocyte number and density changes during early human life. Pediatr Nephrol 2017; 32:823-834. [PMID: 28028615 PMCID: PMC5368211 DOI: 10.1007/s00467-016-3564-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 11/30/2016] [Accepted: 11/30/2016] [Indexed: 01/08/2023]
Abstract
BACKGROUND Podocyte depletion, which drives progressive glomerulosclerosis in glomerular diseases, is caused by a reduction in podocyte number, size or function in the context of increasing glomerular volume. METHODS Kidneys obtained at autopsy from premature and mature infants who died in the first year of life (n = 24) were used to measure podometric parameters for comparison with previously reported data from older kidneys. RESULTS Glomerular volume increased 4.6-fold from 0.13 ± 0.07 μm3 x106 in the pre-capillary loop stage, through 0.35 μm3 x106 at the capillary loop, to 0.60 μm3 x106 at the mature glomerular stage. Podocyte number per glomerulus increased from 326 ± 154 per glomerulus at the pre-capillary loop stage to 584 ± 131 per glomerulus at the capillary loop stage of glomerular development to reach a value of 589 ± 166 per glomerulus in mature glomeruli. Thus, the major podocyte number increase occurs in the early stages of glomerular development, in contradistinction to glomerular volume increase, which continues after birth in association with body growth. CONCLUSIONS As glomeruli continue to enlarge, podocyte density (number per volume) rapidly decreases, requiring a parallel rapid increase in podocyte size that allows podocyte foot processes to maintain complete coverage of the filtration surface area. Hypertrophic stresses on the glomerulus and podocyte during development and early rapid growth periods of life are therefore likely to play significant roles in determining how and when defects in podocyte structure and function due to genetic variants become clinically manifest. Therapeutic strategies aimed at minimizing mismatch between these factors may prove clinically useful.
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35
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Peired AJ, Bitzer M. Albumin: innocent bystander or culprit? Am J Physiol Renal Physiol 2016; 311:F409-10. [PMID: 27306981 DOI: 10.1152/ajprenal.00317.2016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 06/08/2016] [Indexed: 11/22/2022] Open
Affiliation(s)
- Anna J Peired
- Excellence Centre for Research, Transfer and High Education for the Development of De Novo Therapies, Florence, Italy; Department of Biomedical, Experimental and Clinical Sciences, University of Florence, Florence, Italy; and
| | - Markus Bitzer
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
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