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Rosenbloom S, Ramanand A, Stark A, Varghese V, Chalmers D, Au-Yeung N, Kanduri SR, Lukitsch I, Poloni JAT, Keitel E, Franz AP, Martínez-Figueroa C, Sarkar A, Alix-Arbatin MC, Fogo AB, Buchkremer F, Seltzer JR, Velez JCQ. Urinary Vacuolar Casts Are a Unique Type of Casts in Advanced Proteinuric Glomerulopathies. KIDNEY360 2024; 5:216-227. [PMID: 38240639 PMCID: PMC10914204 DOI: 10.34067/kid.0000000000000346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 12/08/2023] [Indexed: 03/01/2024]
Abstract
Key Points Vacuolar casts are a distinct type of casts identifiable by urinary sediment microscopy. Identification of urinary vacuolar casts is associated with the presence of an advanced and severe form of a proteinuric glomerular disease. Background Identification of casts by urinary sediment microscopy is a valuable diagnostic clinical tool for the evaluation of kidney disease. Vacuolar casts are an unrecognized unique type of casts characterized by the presence of nonpolarizable, clear vesicles of various sizes contained within a cast matrix, different from lipid casts, erythrocyte casts, or any other casts. We aimed to gain better understanding of the clinical relevance of these casts by establishing a multinational collaborative group to search for cases in which vacuolar casts were identified. Methods Leveraging an educational social media platform, we conducted a multinational observational study extracting cases of patients who presented with urinary vacuolar casts during evaluation for impaired kidney function. Parameters assessed included degree of proteinuria and kidney dysfunction, clinical and histopathological diagnosis, and severity of renal parenchymal scarring on biopsy. A control group of patients without vacuolar casts was included for comparison. Results Forty-six patients with urinary vacuolar casts were compiled from six countries. Nephrotic range proteinuria (82%), glomerular etiology (98%), and advanced CKD stage (62% 3B-5) were salient features. Histopathological diagnosis was available in 26 (57%) patients. Combining clinical and pathological diagnoses, diabetic nephropathy (48%), arterionephrosclerosis (30%), podocytopathies (15%), and proliferative glomerulonephritides (15%) accounted for most patients. Vacuolization of tubules or podocytes was present in 61% of the specimens. When compared with patients with histopathological diagnoses in which vacuolar casts were not found (n =186), patients with vacuolar casts more frequently had a glomerular etiology (100% versus 71%, P = 0.002), had greater proteinuria (median urine protein-to-creatinine 10.3 versus 2.2 g/g, P < 0.001), and had greater proportion of patients with ≥30% glomerular obsolescence (46% versus 20%, P = 0.003). Conclusions Thus, urinary vacuolar casts are strongly associated with advanced glomerulopathies with severe proteinuria. Future studies should examine their origin, composition, and prognostic value. Podcast This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/K360/2024_01_26_KID0000000000000346.mp3
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Affiliation(s)
- Sarah Rosenbloom
- Department of Nephrology, Ochsner Health, New Orleans, Louisiana
| | - Akanksh Ramanand
- Department of Nephrology, Ochsner Health, New Orleans, Louisiana
- Ochsner Clinical School, The University of Queensland, Brisbane, Queensland, Australia
| | - Anabella Stark
- Department of Nephrology, Ochsner Health, New Orleans, Louisiana
| | - Vipin Varghese
- Department of Nephrology, Ochsner Health, New Orleans, Louisiana
- Ochsner Clinical School, The University of Queensland, Brisbane, Queensland, Australia
| | - Dustin Chalmers
- Department of Nephrology, Ochsner Health, New Orleans, Louisiana
- Ochsner Clinical School, The University of Queensland, Brisbane, Queensland, Australia
| | - Nathan Au-Yeung
- Ochsner Clinical School, The University of Queensland, Brisbane, Queensland, Australia
| | - Swetha R. Kanduri
- Department of Nephrology, Ochsner Health, New Orleans, Louisiana
- Ochsner Clinical School, The University of Queensland, Brisbane, Queensland, Australia
| | - Ivo Lukitsch
- Department of Nephrology, Ochsner Health, New Orleans, Louisiana
| | | | - Elizete Keitel
- Santa Casa de Misericórdia de Porto Alegre, Center for Nephrology and Kidney Transplantation, Porto Alegre, Rio Grande do Sul, Brazil
- Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil
| | - Ana Paula Franz
- Laboratório de Análises Clínicas, Hospital de Clínicas, Passo Fundo, Rio Grande do Sul, Brazil
| | | | | | | | - Agnes B. Fogo
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Florian Buchkremer
- Division of Nephrology, Medical University Department, Kantonsspital Aarau, Aargau, Switzerland
| | - Jay R. Seltzer
- Department of Nephrology, Missouri Baptist Medical Center, St. Louis, Missouri
| | - Juan Carlos Q. Velez
- Department of Nephrology, Ochsner Health, New Orleans, Louisiana
- Ochsner Clinical School, The University of Queensland, Brisbane, Queensland, Australia
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Kriz W, Wiech T, Gröne HJ. Mesangial Injury and Capillary Ballooning Precede Podocyte Damage in Nephrosclerosis. THE AMERICAN JOURNAL OF PATHOLOGY 2022; 192:1670-1682. [PMID: 36150506 DOI: 10.1016/j.ajpath.2022.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/22/2022] [Accepted: 08/30/2022] [Indexed: 06/16/2023]
Abstract
The development of focal and segmental glomerulosclerosis (FSGS) as a consequence of glomerular hypertension resulting from arterial hypertension is widely considered a podocyte disease. However, the primary damage is encountered in the mesangium. In acute settings, mesangial cells disconnect from their insertions to the glomerular basement membrane, causing a ballooning of capillaries and severe changes of the folding pattern of the glomerular basement membrane, of the arrangement of the capillaries, and thereby of the architecture of the tuft. The displacement of capillaries led to contact of podocytes and parietal epithelial cells, initiating the formation of tuft adhesions to Bowman's capsule, the committed lesion to progress to FSGS. In addition, the displacement of capillaries also caused an abnormal stretching of podocytes, resulting in podocyte damage. Thus, the podocyte damage that starts the sequence to FSGS is predicted to develop secondary to the mesangial damage. This sequence was found in two hypertensive rat models of FSGS and in human hypertensive nephrosclerosis.
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Affiliation(s)
- Wilhelm Kriz
- Department of Neuroanatomy, Medical Faculty Mannheim, University Heidelberg, Mannheim, Germany.
| | - Thorsten Wiech
- Nephropathology Section, Institute of Pathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Hermann-Josef Gröne
- Medical Faculty, University of Heidelberg, Heidelberg, Germany; Institute of Pharmacology, University of Marburg, Marburg, Germany
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Li F, Fang Y, Zhuang Q, Cheng M, Moronge D, Jue H, Meyuhas O, Ding X, Zhang Z, Chen JK, Wu H. Blocking ribosomal protein S6 phosphorylation inhibits podocyte hypertrophy and focal segmental glomerulosclerosis. Kidney Int 2022; 102:121-135. [PMID: 35483522 PMCID: PMC10711420 DOI: 10.1016/j.kint.2022.02.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 02/01/2022] [Accepted: 02/17/2022] [Indexed: 10/18/2022]
Abstract
Ribosomal protein S6 (rpS6) phosphorylation mediates the hypertrophic growth of kidney proximal tubule cells. However, the role of rpS6 phosphorylation in podocyte hypertrophy and podocyte loss during the pathogenesis of focal segmental glomerulosclerosis (FSGS) remains undefined. Here, we examined rpS6 phosphorylation levels in kidney biopsy specimens from patients with FSGS and in podocytes from mouse kidneys with Adriamycin-induced FSGS. Using genetic and pharmacologic approaches in the mouse model of FSGS, we investigated the role of rpS6 phosphorylation in podocyte hypertrophy and loss during development and progression of FSGS. Phosphorylated rpS6 was found to be markedly increased in the podocytes of patients with FSGS and Adriamycin-induced FSGS mice. Genetic deletion of the Tuberous sclerosis 1 gene in kidney glomerular podocytes activated mammalian target of rapamycin complex 1 signaling to rpS6 phosphorylation, resulting in podocyte hypertrophy and pathologic features similar to those of patients with FSGS including podocyte loss, leading to segmental glomerulosclerosis. Since protein phosphatase 1 is known to negatively regulate rpS6 phosphorylation, treatment with an inhibitor increased phospho-rpS6 levels, promoted podocyte hypertrophy and exacerbated formation of FSGS lesions. Importantly, blocking rpS6 phosphorylation (either by generating congenic rpS6 knock-in mice expressing non-phosphorylatable rpS6 or by inhibiting ribosomal protein S6 kinase 1-mediated rpS6 phosphorylation with an inhibitor) significantly blunted podocyte hypertrophy, inhibited podocyte loss, and attenuated formation of FSGS lesions. Thus, our study provides genetic and pharmacologic evidence indicating that specifically targeting rpS6 phosphorylation can attenuate the development of FSGS lesions by inhibiting podocyte hypertrophy and associated podocyte depletion.
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Affiliation(s)
- Fang Li
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China; Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China; Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Yili Fang
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China; Department of Nephrology, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Qiyuan Zhuang
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Meichu Cheng
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Nephrology, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Desmond Moronge
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Hao Jue
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Oded Meyuhas
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Xiaoqiang Ding
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Zhigang Zhang
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China.
| | - Jian-Kang Chen
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Huijuan Wu
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China.
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Hodgin JB, Mariani LH, Zee J, Liu Q, Smith AR, Eddy S, Hartman J, Hamidi H, Gaut JP, Palmer MB, Nast CC, Chang A, Hewitt S, Gillespie BW, Kretzler M, Holzman LB, Barisoni L. Quantification of Glomerular Structural Lesions: Associations With Clinical Outcomes and Transcriptomic Profiles in Nephrotic Syndrome. Am J Kidney Dis 2022; 79:807-819.e1. [PMID: 34864148 DOI: 10.1053/j.ajkd.2021.10.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Accepted: 10/20/2021] [Indexed: 12/18/2022]
Abstract
RATIONALE & OBJECTIVE The current classification system for focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD) does not fully capture the complex structural changes in kidney biopsies nor the clinical and molecular heterogeneity of these diseases. STUDY DESIGN Prospective observational cohort study. SETTING & PARTICIPANTS 221 MCD and FSGS patients enrolled in the Nephrotic Syndrome Study Network (NEPTUNE). EXPOSURE The NEPTUNE Digital Pathology Scoring System (NDPSS) was applied to generate scores for 37 glomerular descriptors. OUTCOME Time from biopsy to complete proteinuria remission, time from biopsy to kidney disease progression (40% estimated glomerular filtration rate [eGFR] decline or kidney failure), and eGFR over time. ANALYTICAL APPROACH Cluster analysis was used to group patients with similar morphologic characteristics. Glomerular descriptors and patient clusters were assessed for associations with outcomes using adjusted Cox models and linear mixed models. Messenger RNA from glomerular tissue was used to assess differentially expressed genes between clusters and identify genes associated with individual descriptors driving cluster membership. RESULTS Three clusters were identified: X (n = 56), Y (n = 68), and Z (n = 97). Clusters Y and Z had higher probabilities of proteinuria remission (HRs of 1.95 [95% CI, 0.99-3.85] and 3.29 [95% CI, 1.52-7.13], respectively), lower hazards of disease progression (HRs of 0.22 [95% CI, 0.08-0.57] and 0.11 [95% CI, 0.03-0.45], respectively), and lower loss of eGFR over time compared with X. Cluster X had 1,920 genes that were differentially expressed compared with Y+Z; these reflected activation of pathways of immune response and inflammation. Six descriptors driving the clusters individually correlated with clinical outcomes and gene expression. LIMITATIONS Low prevalence of some descriptors and biopsy at a single time point. CONCLUSIONS The NDPSS allows for categorization of FSGS/MCD patients into clinically and biologically relevant subgroups, and uncovers histologic parameters associated with clinical outcomes and molecular signatures not included in current classification systems.
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Affiliation(s)
- Jeffrey B Hodgin
- Renal Pathology, Department of Pathology, University of Michigan, Ann Arbor, Michigan.
| | - Laura H Mariani
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Jarcy Zee
- Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, Pennsylvania; Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Qian Liu
- Arbor Research Collaborative for Health, Ann Arbor, Michigan, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Abigail R Smith
- Arbor Research Collaborative for Health, Ann Arbor, Michigan, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sean Eddy
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - John Hartman
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Habib Hamidi
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Joseph P Gaut
- Department of Pathology and Immunology, and Internal Medicine, Washington University, St. Louis, Missouri
| | - Matthew B Palmer
- Department of Pathology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Cynthia C Nast
- Department of Pathology, Cedars-Sinai Medical Center, Los Angeles, California
| | - Anthony Chang
- Department of Pathology, University of Chicago Medicine, Chicago, Illinois
| | - Stephen Hewitt
- Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Brenda W Gillespie
- Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, Michigan
| | - Matthias Kretzler
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Lawrence B Holzman
- Renal-Electrolyte and Hypertension Division, Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Laura Barisoni
- Department of Pathology, Division of AI & Computational Pathology, Duke University, Durham, North Carolina; Department of Medicine, Division of Nephrology, Duke University, Durham, North Carolina.
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5
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Yin L, Yu L, He JC, Chen A. Controversies in Podocyte Loss: Death or Detachment? Front Cell Dev Biol 2021; 9:771931. [PMID: 34881244 PMCID: PMC8645964 DOI: 10.3389/fcell.2021.771931] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 11/03/2021] [Indexed: 12/21/2022] Open
Abstract
Glomerular podocytes are characterized by terminally differentiated epithelial cells with limited proliferating ability; thus, podocyte loss could not be fully compensated by podocyte regeneration. A large body of clinical studies collectively demonstrated that podocyte loss correlated with glomerular diseases progression. Both podocyte death and podocyte detachment lead to podocyte loss; however, which one is the main cause remains controversial. Up to date, multiple mechanisms are involved in podocyte death, including programmed apoptotic cell death (apoptosis and anoikis), programmed nonapoptotic cell death (autophagy, entosis, and podoptosis), immune-related cell death (pyroptosis), and other types of cell death (necroptosis and mitotic catastrophe-related cell death). Apoptosis is considered a common mechanism of podocyte loss; however, most of the data were generated in vitro and the evidence of in vivo podocyte apoptosis is limited. The isolation of podocytes in the urine and subsequent culture of urinary podocytes in vitro suggest that detachment of viable podocytes could be another important mechanism for podocyte loss. In this review, we summarize recent advances that address this controversial topic on the specific circumstances of podocyte loss.
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Affiliation(s)
- Lijun Yin
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, Institute of Nephrology, The Second Xiangya Hospital at Central South University, Changsha, China
| | - Lu Yu
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, Institute of Nephrology, The Second Xiangya Hospital at Central South University, Changsha, China.,Department of Health Sciences, Boston University College of Health and Rehabilitation Sciences: Sargent College, Boston University, Boston, MA, United States
| | - John Cijiang He
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States.,Renal Program, James J. Peters Veterans Affairs Medical Center at Bronx, New York, NY, United States
| | - Anqun Chen
- Hunan Key Laboratory of Kidney Disease and Blood Purification, Department of Nephrology, Institute of Nephrology, The Second Xiangya Hospital at Central South University, Changsha, China
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6
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Afsar B, Afsar RE, Demiray A, Covic A, Kanbay M. Deciphering nutritional interventions for podocyte structure and function. Pharmacol Res 2021; 172:105852. [PMID: 34450318 DOI: 10.1016/j.phrs.2021.105852] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/22/2021] [Accepted: 08/22/2021] [Indexed: 12/11/2022]
Abstract
Despite increasing awareness and therapeutic options chronic kidney disease (CKD) is still and important health problem and glomerular diseases constitute and important percentage of CKD. Proteinuria/albuminuria is not just a marker; but it also plays a direct pathogenic role in renal disease progression of CKD. Glomerular filtration barrier (GFB) which consists of fenestrated endothelial cells, fused basal membrane and interdigitating podocyte foot process and filtration slits between foot process is the major barrier for proteinuria/albuminuria. Many glomerular diseases are characterized by disruption of GFB podocytes, foot process and slit diaphragm. Many proteinuric diseases are non-specifically targeted by therapeutic agents such as steroids and calcineurin inhibitors with systemic side effects. Thus, there is unmet need for more efficient and less toxic therapeutic options to treat glomerular diseases. In recent years, modification of dietary intake, has been gained to treat pathologic processes introducing the concept of 'food as a medicine'. The effect of various nutritional products on podocyte function and structure is also trending, especially in recent years. In the current review, we summarized the effect of nutritional interventions on podocyte function and structure.
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Affiliation(s)
- Baris Afsar
- Division of Nephrology, Department of Nephrology, Suleyman Demirel University School of Medicine, Isparta, Turkey.
| | - Rengin Elsurer Afsar
- Division of Nephrology, Department of Nephrology, Suleyman Demirel University School of Medicine, Isparta, Turkey
| | - Atalay Demiray
- Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | - Adrian Covic
- Department of Nephrology, Grigore T. Popa' University of Medicine, Iasi, Romania
| | - Mehmet Kanbay
- Division of Nephrology, Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
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7
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Urinary mRNA Expression of Glomerular Podocyte Markers in Glomerular Disease and Renal Transplant. Diagnostics (Basel) 2021; 11:diagnostics11081499. [PMID: 34441433 PMCID: PMC8392587 DOI: 10.3390/diagnostics11081499] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 11/20/2022] Open
Abstract
The research of novel markers in urinary samples, for the description of renal damage, is of high interest, and several works demonstrated the value of urinary mRNA quantification for the search of events related to renal disease or affecting the outcome of transplant kidneys. In the present pilot study, a comparison of the urine mRNA expression of specific podocyte markers among patients who had undergone clinical indication to renal transplanted (RTx, n = 20) and native (N, n = 18) renal biopsy was performed. The aim of this work was to identify genes involved in podocytes signaling and cytoskeletal regulation (NPHS1, NPHS2, SYNPO, WT1, TRPC6, GRM1, and NEUROD) in respect to glomerular pathology. We considered some genes relevant for podocytes signaling and for the function of the glomerular filter applying an alternative normalization approach. Our results demonstrate the WT1 urinary mRNA increases in both groups and it is helpful for podocyte normalization. Furthermore, an increase in the expression of TRPC6 after all kinds of normalizations was observed. According to our data, WT1 normalization might be considered an alternative approach to correct the expression of urinary mRNA. In addition, our study underlines the importance of slit diaphragm proteins involved in calcium disequilibrium, such as TRPC6.
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Bondue T, Arcolino FO, Veys KRP, Adebayo OC, Levtchenko E, van den Heuvel LP, Elmonem MA. Urine-Derived Epithelial Cells as Models for Genetic Kidney Diseases. Cells 2021; 10:cells10061413. [PMID: 34204173 PMCID: PMC8230018 DOI: 10.3390/cells10061413] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/28/2021] [Accepted: 06/02/2021] [Indexed: 12/11/2022] Open
Abstract
Epithelial cells exfoliated in human urine can include cells anywhere from the urinary tract and kidneys; however, podocytes and proximal tubular epithelial cells (PTECs) are by far the most relevant cell types for the study of genetic kidney diseases. When maintained in vitro, they have been proven extremely valuable for discovering disease mechanisms and for the development of new therapies. Furthermore, cultured patient cells can individually represent their human sources and their specific variants for personalized medicine studies, which are recently gaining much interest. In this review, we summarize the methodology for establishing human podocyte and PTEC cell lines from urine and highlight their importance as kidney disease cell models. We explore the well-established and recent techniques of cell isolation, quantification, immortalization and characterization, and we describe their current and future applications.
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Affiliation(s)
- Tjessa Bondue
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
| | - Fanny O. Arcolino
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
| | - Koenraad R. P. Veys
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
- Department of Pediatrics, Division of Pediatric Nephrology, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Oyindamola C. Adebayo
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
- Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Elena Levtchenko
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
- Department of Pediatrics, Division of Pediatric Nephrology, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Lambertus P. van den Heuvel
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
- Department of Pediatric Nephrology, Radboud University Medical Center, 6500 Nijmegen, The Netherlands
| | - Mohamed A. Elmonem
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo 11628, Egypt
- Correspondence:
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9
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Nishad R, Mukhi D, Singh AK, Motrapu M, Chintala K, Tammineni P, Pasupulati AK. Growth hormone induces mitotic catastrophe of glomerular podocytes and contributes to proteinuria. Cell Death Dis 2021; 12:342. [PMID: 33795655 PMCID: PMC8016968 DOI: 10.1038/s41419-021-03643-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/15/2021] [Accepted: 03/16/2021] [Indexed: 12/13/2022]
Abstract
Glomerular podocytes are integral members of the glomerular filtration barrier in the kidney and are crucial for glomerular permselectivity. These highly differentiated cells are vulnerable to an array of noxious stimuli that prevail in several glomerular diseases. Elevated circulating growth hormone (GH) levels are associated with podocyte injury and proteinuria in diabetes. However, the precise mechanism(s) by which excess GH elicits podocytopathy remains to be elucidated. Previous studies have shown that podocytes express GH receptor (GHR) and induce Notch signaling when exposed to GH. In the present study, we demonstrated that GH induces TGF-β1 signaling and provokes cell cycle reentry of otherwise quiescent podocytes. Though differentiated podocytes reenter the cell cycle in response to GH and TGF-β1, they cannot accomplish cytokinesis, despite karyokinesis. Owing to this aberrant cell cycle event, GH- or TGF-β1-treated cells remain binucleated and undergo mitotic catastrophe. Importantly, inhibition of JAK2, TGFBR1 (TGF-β receptor 1), or Notch prevented cell cycle reentry of podocytes and protected them from mitotic catastrophe associated with cell death. Inhibition of Notch activation prevents GH-dependent podocyte injury and proteinuria. Similarly, attenuation of GHR expression abated Notch activation in podocytes. Kidney biopsy sections from patients with diabetic nephropathy (DN) show activation of Notch signaling and binucleated podocytes. These data indicate that excess GH induced TGF-β1-dependent Notch1 signaling contributes to the mitotic catastrophe of podocytes. This study highlights the role of aberrant GH signaling in podocytopathy and the potential application of TGF-β1 or Notch inhibitors, as a therapeutic agent for DN.
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Affiliation(s)
- Rajkishor Nishad
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Dhanunjay Mukhi
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Ashish Kumar Singh
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Manga Motrapu
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Kumaraswami Chintala
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Prasad Tammineni
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Anil K Pasupulati
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India.
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10
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Glomerular filtrate affects the dynamics of podocyte detachment in a model of diffuse toxic podocytopathy. Kidney Int 2021; 99:1149-1161. [PMID: 33582108 DOI: 10.1016/j.kint.2020.12.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 12/27/2020] [Accepted: 12/29/2020] [Indexed: 11/22/2022]
Abstract
Podocyte injury and subsequent detachment are hallmarks of progressive glomerulosclerosis. In addition to cell injury, unknown mechanical forces on the injured podocyte may promote detachment. To identify the nature of these mechanical forces, we studied the dynamics of podocyte detachment using sequential ultrastructural geometry analysis by transmission electron microscopy in NEP25, a mouse model of podocytopathy induced by anti-Tac(Fv)-PE38 (LMB2), a fusion protein attached to Pseudomonas exotoxin A, targeting CD25 on podocytes. After LMB2 injection, foot process effacement occurred on day three but detachment commenced on day eight and extended to day ten, reaching toward the urinary pole in clusters. Podocyte detachment was associated with foot process effacement covering over 60% of the glomerular basement membrane length. However, approximately 25% of glomeruli with diffuse (over 80%) foot process effacement showed no detachment. Blocking glomerular filtration via unilateral ureteral obstruction resulted in diffuse foot process effacement but no pseudocysts or detachment, whereas uninephrectomy increased pseudocysts and accelerated detachment, indicating that glomerular filtrate drives podocyte detachment via pseudocyst formation as a forerunner. Additionally, more detachment was observed in juxtamedullary glomeruli than in superficial glomeruli. Thus, glomerular filtrate drives the dynamics of podocyte detachment in this model of podocytopathy. Hence, foot process effacement may be a prerequisite allowing filtrate to generate local mechanical forces that expand the subpodocyte space forming pseudocysts, promote podocyte detachment and subsequent segmental sclerosis.
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11
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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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Hansen KUI, Siegerist F, Daniel S, Schindler M, Iervolino A, Blumenthal A, Daniel C, Amann K, Zhou W, Endlich K, Endlich N. Prolonged podocyte depletion in larval zebrafish resembles mammalian focal and segmental glomerulosclerosis. FASEB J 2020; 34:15961-15974. [PMID: 33070374 DOI: 10.1096/fj.202000724r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 09/15/2020] [Accepted: 09/21/2020] [Indexed: 12/12/2022]
Abstract
Focal and segmental glomerulosclerosis (FSGS) is a histological pattern frequently found in patients with nephrotic syndrome that often progress to end-stage kidney disease. The initial step in development of this histologically defined entity is injury and ultimately depletion of podocytes, highly arborized interdigitating cells on the glomerular capillaries with important function for the glomerular filtration barrier. Since there are still no causal therapeutic options, animal models are needed to develop new treatment strategies. Here, we present an FSGS-like model in zebrafish larvae, an eligible vertebrate model for kidney research. In a transgenic zebrafish strain, podocytes were depleted, and the glomerular response was investigated by histological and morphometrical analysis combined with immunofluorescence staining and ultrastructural analysis by transmission electron microscopy. By intravenous injection of fluorescent high-molecular weight dextran, we confirmed leakage of the size selective filtration barrier. Additionally, we observed severe podocyte foot process effacement of remaining podocytes, activation of proximal tubule-like parietal epithelial cells identified by ultrastructural cytomorphology, and expression of proximal tubule markers. These activated cells deposited extracellular matrix on the glomerular tuft which are all hallmarks of FSGS. Our findings indicate that glomerular response to podocyte depletion in larval zebrafish resembles human FSGS in several important characteristics. Therefore, this model will help to investigate the disease development and the effects of potential drugs in a living organism.
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Affiliation(s)
| | - Florian Siegerist
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Sophie Daniel
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Maximilian Schindler
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Anna Iervolino
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany.,Biogem Research Institute Gaetano Salvatore, Ariano Irpino, Italy
| | - Antje Blumenthal
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Christoph Daniel
- Department of Nephropathology, Institute of Pathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Kerstin Amann
- Department of Nephropathology, Institute of Pathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Weibin Zhou
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York City, NY, USA
| | - Karlhans Endlich
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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Blaine J, Dylewski J. Regulation of the Actin Cytoskeleton in Podocytes. Cells 2020; 9:cells9071700. [PMID: 32708597 PMCID: PMC7408282 DOI: 10.3390/cells9071700] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 06/30/2020] [Accepted: 07/07/2020] [Indexed: 12/13/2022] Open
Abstract
Podocytes are an integral part of the glomerular filtration barrier, a structure that prevents filtration of large proteins and macromolecules into the urine. Podocyte function is dependent on actin cytoskeleton regulation within the foot processes, structures that link podocytes to the glomerular basement membrane. Actin cytoskeleton dynamics in podocyte foot processes are complex and regulated by multiple proteins and other factors. There are two key signal integration and structural hubs within foot processes that regulate the actin cytoskeleton: the slit diaphragm and focal adhesions. Both modulate actin filament extension as well as foot process mobility. No matter what the initial cause, the final common pathway of podocyte damage is dysregulation of the actin cytoskeleton leading to foot process retraction and proteinuria. Disruption of the actin cytoskeleton can be due to acquired causes or to genetic mutations in key actin regulatory and signaling proteins. Here, we describe the major structural and signaling components that regulate the actin cytoskeleton in podocytes as well as acquired and genetic causes of actin dysregulation.
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Affiliation(s)
- Judith Blaine
- Renal Division, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA;
| | - James Dylewski
- Renal Division, University of Colorado Anschutz Medical Campus and Denver Health Medical Center, Aurora, CO 80045, USA
- Correspondence: ; Tel.: +303-724-4841
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Kriz W. The Inability of Podocytes to Proliferate: Cause, Consequences, and Origin. Anat Rec (Hoboken) 2019; 303:2588-2596. [PMID: 31606944 DOI: 10.1002/ar.24291] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/07/2019] [Accepted: 08/26/2019] [Indexed: 12/24/2022]
Abstract
This study presents a theoretical analysis of the problems related to the inability of podocytes to proliferate. The basis of these problems is the very high rate of glomerular filtration. Podocytes do not in general die by apoptosis or necrosis but are lost by detachment from the glomerular basement membrane (GBM) as viable cells. Podocytes situated on the outside of the filtration barrier and attached to the GBM only by their foot processes are permanently exposed to the flow dynamic forces of the high filtration rate tending to detach them from the GBM. The major challenge seems to consist of the high shear stresses on the foot processes within the filtration slits due to filtrate flow. Healthy podocytes are able to resist this challenge, injured podocytes are not, and may undergo foot process detachment, leading to a gap in the podocyte cover of the GBM. This represents a mortal event. Like a dam break, such a leak cannot be repaired. The ongoing exposure to filtrate flow prevents any attempt to close the gap, thus preventing any regeneration including cell proliferation. An improvement of this precarious situation consists of healing by scarring that may involve only one lobule of the glomerulus, permitting the remaining lobules to maintain filtration. An answer to the question of which waste product requires such a high filtration rate for its excretion may be in the huge quantity of circulating peptides, a problem that dates far back in evolution.
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Affiliation(s)
- Wilhelm Kriz
- Department of Neuroanatomy, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
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Samsu N, Soeharto S, Rifai M, Rudijanto A. Rosmarinic acid monotherapy is better than the combination of rosmarinic acid and telmisartan in preventing podocyte detachment and inhibiting the progression of diabetic nephropathy in rats. Biologics 2019; 13:179-190. [PMID: 31564826 PMCID: PMC6722456 DOI: 10.2147/btt.s214820] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 08/19/2019] [Indexed: 02/02/2023]
Abstract
BACKGROUND Podocyte injury and its subsequent detachment play a critical role in the development and progression of diabetic nephropathy (DN). The objective of this study was to investigate the effect of rosmarinic acid (RA) in preventing podocyte detachment and inhibiting the progression of DN in streptozotocin (STZ)-induced diabetic in rats. METHODS We used 20 adult male Wistar rats as experimental animals, which were randomly divided into 5 groups (n=4 per group): nondiabetic rat group (negative control) and 4 groups of STZ-induced diabetic rats, namely, 1 group untreated diabetic rats (positive control) and 3 groups treated diabetic rats with RA 75 mg/kg, telmisartan (TMS) 1 mg/kg and combination of RA 75 mg/kg with TMS 1 mg/kg), respectively. After 8 weeks of therapy, urinary levels of podocin, nephrin and albumin and also serum cystatin C levels were examined by ELISA. The expression of p65 nuclear factor-kB by immunohistochemistry whereas expression of podocin and nephrin glomerulus were examined by immunofluorescence. RESULTS In the treated diabetic groups, we found that urinary level of podocin and nephrin, albumin urine excretion and serum cystatin C levels were significantly lower than the positive control group. Compared to negative controls, the group of treated diabetic rats did not differ significantly in preventing increased excretion of urinary nephrin and podocin. Meanwhile, treatment with RA monotherapy was significantly better than TMS or a combination of RA with TMS in reducing albumin excretion and preventing decreased kidney function. CONCLUSION In STZ-induced diabetic rats, RA can prevent podocyte detachment. Treatment with RA and TMS either monotherapy or in combination can inhibit the development and progression of DN. However, the combination of both did not show a synergistic effect, even have higher urinary albumin excretion and worse kidney function compared to the RA monotherapy.
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Affiliation(s)
- Nur Samsu
- Department of Internal Medicine, Division of Nephrology and Hypertension, Faculty of Medicine
| | | | - Muhaimin Rifai
- Department of Biology, Faculty of Mathematics and Sciences
| | - Achmad Rudijanto
- Department of Internal Medicine, Division of Endocrinology and Metabolic, Faculty of Medicine, Universitas Brawijaya, Malang, Indonesia
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Ichimura K, Miyaki T, Kawasaki Y, Kinoshita M, Kakuta S, Sakai T. Morphological Processes of Foot Process Effacement in Puromycin Aminonucleoside Nephrosis Revealed by FIB/SEM Tomography. J Am Soc Nephrol 2018; 30:96-108. [PMID: 30514724 DOI: 10.1681/asn.2018020139] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 11/07/2018] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Foot process effacement is one of the pathologic indicators of podocyte injury. However, the morphologic changes associated with it remain unclear. METHODS To clarify the developmental process, we analyzed puromycin nephrotic podocytes reconstructed from serial focused-ion beam/scanning electron microscopy (FIB/SEM) images. RESULTS Intact podocytes consisted of four subcellular compartments: cell body, primary process, ridge-like prominence (RLP), and foot process. The RLP, a longitudinal protrusion from the basal surface of the cell body and primary process, served as an adhesive apparatus for the cell body and primary process to attach to the glomerular basement membrane. Foot processes protruded from both sides of the RLP. In puromycin nephrotic podocytes, foot process effacement occurred in two ways: by type-1 retraction, where the foot processes retracted while maintaining their rounded tips; or type-2 retraction, where they narrowed across their entire lengths, tapering toward the tips. Puromycin nephrotic podocytes also exhibited several alterations associated with foot process effacement, such as deformation of the cell body, retraction of RLPs, and cytoplasmic fragmentation. Finally, podocytes were reorganized into a broad, flattened shape. CONCLUSIONS The three-dimensional reconstruction of podocytes by serial FIB/SEM images revealed the morphologic changes involved in foot process effacement in greater detail than previously described.
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Affiliation(s)
- Koichiro Ichimura
- Department of Anatomy and Life Structure and .,Laboratory of Morphology and Image Analysis, Research Support Center, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | | | | | | | - Soichiro Kakuta
- Laboratory of Morphology and Image Analysis, Research Support Center, Juntendo University Graduate School of Medicine, Tokyo, Japan
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Siegerist F, Endlich K, Endlich N. Novel Microscopic Techniques for Podocyte Research. Front Endocrinol (Lausanne) 2018; 9:379. [PMID: 30050501 PMCID: PMC6050355 DOI: 10.3389/fendo.2018.00379] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/22/2018] [Indexed: 01/16/2023] Open
Abstract
Together with endothelial cells and the glomerular basement membrane, podocytes form the size-specific filtration barrier of the glomerulus with their interdigitating foot processes. Since glomerulopathies are associated with so-called foot process effacement-a severe change of well-formed foot processes into flat and broadened processes-visualization of the three-dimensional podocyte morphology is a crucial part for diagnosis of nephrotic diseases. However, interdigitating podocyte foot processes are too narrow to be resolved by classic light microscopy due to Ernst Abbe's law making electron microscopy necessary. Although three dimensional electron microscopy approaches like serial block face and focused ion beam scanning electron microscopy and electron tomography allow volumetric reconstruction of podocytes, these techniques are very time-consuming and too specialized for routine use or screening purposes. During the last few years, different super-resolution microscopic techniques were developed to overcome the optical resolution limit enabling new insights into podocyte morphology. Super-resolution microscopy approaches like three dimensional structured illumination microscopy (3D-SIM), stimulated emission depletion microscopy (STED) and localization microscopy [stochastic optical reconstruction microscopy (STORM), photoactivated localization microscopy (PALM)] reach resolutions down to 80-20 nm and can be used to image and further quantify podocyte foot process morphology. Furthermore, in vivo imaging of podocytes is essential to study the behavior of these cells in situ. Therefore, multiphoton laser microscopy was a breakthrough for in vivo studies of podocytes in transgenic animal models like rodents and zebrafish larvae because it allows imaging structures up to several hundred micrometer in depth within the tissue. Additionally, along with multiphoton microscopy, lightsheet microscopy is currently used to visualize larger tissue volumes and therefore image complete glomeruli in their native tissue context. Alongside plain visualization of cellular structures, atomic force microscopy has been used to study the change of mechanical properties of podocytes in diseased states which has been shown to be a culprit in podocyte maintenance. This review discusses recent advances in the field of microscopic imaging and demonstrates their currently used and other possible applications for podocyte research.
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Affiliation(s)
| | | | - Nicole Endlich
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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18
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The long journey through renal filtration: new pieces in the puzzle of slit diaphragm architecture. Curr Opin Nephrol Hypertens 2018; 26:148-153. [PMID: 28212178 DOI: 10.1097/mnh.0000000000000322] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
PURPOSE OF REVIEW The podocyte slit diaphragm is probably the least understood component of the kidney filtration barrier. In this review, we aim to integrate the most recent findings on the molecular make-up and structural architecture of this specialized cell-cell junction into a current concept of glomerular filtration. RECENT FINDINGS Analysis of cryopreserved mammalian tissue revealed a bipartite composition of the slit diaphragm. Single NEPH1 molecules span the lower part of the slit close to the glomerular basement membrane whereas NEPHRIN molecules are positioned in the apical part toward Bowman's space. This molecular arrangement could lead to heterogeneous ellipsoidal and circular pores, which are mainly located in the central region of the slit diaphragm. SUMMARY Despite having been first identified in the 1970s, the slit diaphragm's structural architecture has not been fully elucidated to date and remains an area of intense research and scientific debate. The slit diaphragm has been initially described as a rigid 'zipper-like' structure in which periodic, rod-like units extend from a podocyte foot processes to a linear central bar, giving rise to homogeneous 4 × 14 nm pores. Several recent findings have challenged these long-held beliefs and instead pointed to an unanticipated complexity of slit diaphragm structure. High-resolution ultrastructural analysis found evidence that the slit diaphragm is a dynamic and adjustable cell-cell junction that forms a nonclogging barrier within the renal filtration system.
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Daehn IS. Glomerular Endothelial Cell Stress and Cross-Talk With Podocytes in Early [corrected] Diabetic Kidney Disease. Front Med (Lausanne) 2018; 5:76. [PMID: 29629372 PMCID: PMC5876248 DOI: 10.3389/fmed.2018.00076] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 03/07/2018] [Indexed: 12/11/2022] Open
Abstract
Diabetic kidney disease (DKD) is one of the major causes of morbidity and mortality in diabetic patients and also the leading single cause of end-stage renal disease in the United States. A large proportion of diabetic patients develop DKD and others don't, even with comparable blood glucose levels, indicating a significant genetic component of disease susceptibility. The glomerulus is the primary site of diabetic injury in the kidney, glomerular hypertrophy and podocyte depletion are glomerular hallmarks of progressive DKD, and the degree of podocyte loss correlates with severity of the disease. We know that chronic hyperglycemia contributes to both microvascular and macrovascular complications, as well as podocyte injury. We are beginning to understand the role of glomerular endothelial injury, as well as the involvement of reactive oxygen species and mitochondrial stress, which play a direct role in DKD and in other diabetic complications. There is, however, a gap in our knowledge that links genetic susceptibility to early molecular mechanisms and proteinuria in DKD. Emerging research that explores glomerular cell's specific responses to diabetes and cell cross-talk will provide mechanistic clues that underlie DKD and provide novel avenues for therapeutic intervention.
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Affiliation(s)
- Ilse Sofia Daehn
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, The Charles Bronfman Institute for Personalized Medicine, New York City, NY, United States
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20
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Kriz W, Lemley KV. Potential relevance of shear stress for slit diaphragm and podocyte function. Kidney Int 2018; 91:1283-1286. [PMID: 28501303 DOI: 10.1016/j.kint.2017.02.032] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/07/2017] [Accepted: 02/24/2017] [Indexed: 11/30/2022]
Abstract
Filtrate flow through the glomerular barrier produces shear stresses that tend to disconnect podocytes from the glomerular basement membrane. Forces are highest within the filtration slits. The slit diaphragm mechanically balances the lateral components of the shear stresses on opposing foot processes, preventing widening of the slit.
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Affiliation(s)
- Wilhelm Kriz
- Department of Neuroanatomy, Medical Faculty Mannheim, Germany.
| | - Kevin V Lemley
- Division of Nephrology, Children's Hospital Los Angeles, California, USA
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Abu Hamad R, Berman S, Hachmo Y, Stark M, Hasan F, Doenyas-Barak K, Efrati S. Response of Renal Podocytes to Excessive Hydrostatic Pressure: a Pathophysiologic Cascade in a Malignant Hypertension Model. Kidney Blood Press Res 2017; 42:1104-1118. [PMID: 29224013 DOI: 10.1159/000485774] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 11/28/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Renal injuries induced by increased intra-glomerular pressure coincide with podocyte detachment from the glomerular basement membrane (GBM). In previous studies, it was demonstrated that mesangial cells have a crucial role in the pathogenesis of malignant hypertension. However, the exact pathophysiological cascade responsible for podocyte detachment and its relationship with mesangial cells has not been fully elucidated yet and this was the aim of the current study. METHODS Rat renal mesangial or podocytes were exposed to high hydrostatic pressure in an in-vitro model of malignant hypertension. The resulted effects on podocyte detachment, apoptosis and expression of podocin and integrinβ1 in addition to Angiotensin-II and TGF-β1 generation were evaluated. To simulate the paracrine effect podocytes were placed in mesangial cell media pre-exposed to pressure, or in media enriched with Angiotensin-II, TGF-β1 or receptor blockers. RESULTS High pressure resulted in increased Angiotensin-II levels in mesangial and podocyte cells. Angiotensin-II via the AT1 receptors reduced podocin expression and integrinβ1, culminating in detachment of both viable and apoptotic podocytes. Mesangial cells exposed to pressure had a greater increase in Angiotensin-II than pressure-exposed podocytes. The massively increased concentration of Angiotensin-II by mesangial cells, together with increased TGF-β1 production, resulted in increased apoptosis and detachment of non-viable apoptotic podocytes. Unlike the direct effect of pressure on podocytes, the mesangial mediated effects were not related to changes in adhesion proteins expression. CONCLUSIONS Hypertension induces podocyte detachment by autocrine and paracrine effects. In a direct response to pressure, podocytes increase Angiotensin-II levels. This leads, via AT1 receptors, to structural changes in adhesion proteins, culminating in viable podocyte detachment. Paracrine effects of hypertension, mediated by mesangial cells, lead to higher levels of both Angiotensin-II and TGF-β1, culminating in apoptosis and detachment of non-viable podocytes.
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Affiliation(s)
| | - Sylvia Berman
- Research & Development Unit, Zerifin, Israel.,Nephrology Division, Assaf-Harofeh Medical Center, Zerifin, affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
| | | | - Moshe Stark
- Research & Development Unit, Zerifin, Israel
| | - Fadia Hasan
- Research & Development Unit, Zerifin, Israel
| | - Keren Doenyas-Barak
- Nephrology Division, Assaf-Harofeh Medical Center, Zerifin, affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
| | - Shai Efrati
- Research & Development Unit, Zerifin, Israel.,Nephrology Division, Assaf-Harofeh Medical Center, Zerifin, affiliated to Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel
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From tubular sublimate nephropathy via urinary concentrating mechanism to glomerular disease—Wilhelm Kriz’s contribution to modern nephrology. Pflugers Arch 2017. [DOI: 10.1007/s00424-017-2010-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Combined use of electron microscopy and intravital imaging captures morphological and functional features of podocyte detachment. Pflugers Arch 2017; 469:965-974. [PMID: 28664407 DOI: 10.1007/s00424-017-2020-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 06/13/2017] [Accepted: 06/14/2017] [Indexed: 12/12/2022]
Abstract
The development of podocyte injury and albuminuria in various glomerular pathologies is still incompletely understood due to technical limitations in studying the glomerular filtration barrier (GFB) in real-time. We aimed to directly visualize the early morphological and functional changes of the GFB during the development of focal segmental glomerulosclerosis (FSGS) using a combination of transmission electron microscopy (TEM) and in vivo multiphoton microscopy (MPM) in the rat puromycin aminonucleoside (PAN) model. We hypothesized that this combined TEM + MPM experimental approach would provide a major technical improvement that would benefit our mechanistic understanding of podocyte detachment. Male Sprague-Dawley (for TEM) or Munich-Wistar-Frömter (for MPM) rats were given a single dose of 100-150 mg/kg body weight PAN i.p. and were either sacrificed and the kidneys processed for TEM or surgically instrumented for in vivo MPM imaging at various times 2-14 days after PAN administration. Both techniques demonstrated hypertrophy and cystic dilatations of the subpodocyte space that developed as early as 2-3 days after PAN. Adhesions of the visceral epithelium to the parietal Bowman's capsule (synechiae) appeared at days 8-10. TEM provided unmatched resolution of podocyte foot process remodeling, while MPM revealed the rapid dynamics of pseudocyst filling, emptying, and rupture, as well as endothelial and podocyte injury, misdirected filtration, and podocyte shedding. Due to the complementary advantages of TEM and MPM, this combined approach can provide an unusally comprehensive and dynamic portrayal of the alterations in podocyte morphology and function during FSGS development. The results advance our understanding of the role and importance of the various cell types, hemodynamics, and mechanical forces in the development of glomerular pathology.
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Nagata M, Kobayashi N, Hara S. Focal segmental glomerulosclerosis; why does it occur segmentally? Pflugers Arch 2017; 469:983-988. [PMID: 28664408 DOI: 10.1007/s00424-017-2023-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 06/17/2017] [Accepted: 06/19/2017] [Indexed: 12/12/2022]
Abstract
Podocyte loss is the fundamental basis of glomerulosclerosis. Focal segmental glomerulosclerosis (FSGS) is a progressive glomerular disease, and its glomerular features are a prototype of podocyte loss-driven glomerulosclerosis. The glomerular pathology of FSGS is characterized by a focal and segmental location of the sclerotic lesions in human FSGS; segmental sclerosis often shows simultaneous intra- and extra-capillary changes, including parietal cell migration, capillary collapse, hyaline deposition, and intra-capillary thrombi and occasional hypercellularity. This suggests that local cellular events, initiated by podocyte loss, are the basis of the segmental lesions in FSGS. Using podocyte-specific injury by toxin administration, a series of recent works has identified the cellular basis of the glomerular response to podocyte loss. This review discusses the molecular pathway of the local response to podocyte loss and its progression to sclerosis. Recent results suggest that segmental sclerosis is a physiological tissue response aimed at halting protein leakage from a disrupted filtration barrier.
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Affiliation(s)
- Michio Nagata
- Kidney and Vascular Pathology, Faculty of Medicine, University of Tsukuba, Ten-nodai 1-1-1, Tsukuba-City, Ibaraki, 305-8577, Japan.
| | - Namiko Kobayashi
- Nephrology, Tokyo Medical and Dental University, Yushima 1-5-45, Bunkyo-ku, Tokyo, 113-850, Japan
| | - Satoshi Hara
- Rheumatology, Kanazawa University Graduate School of Medicine, Takara-machi 13-1, Kanazawa, Ishikawa, 920-8671, Japan
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The FERM protein EPB41L5 regulates actomyosin contractility and focal adhesion formation to maintain the kidney filtration barrier. Proc Natl Acad Sci U S A 2017; 114:E4621-E4630. [PMID: 28536193 DOI: 10.1073/pnas.1617004114] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Podocytes form the outer part of the glomerular filter, where they have to withstand enormous transcapillary filtration forces driving glomerular filtration. Detachment of podocytes from the glomerular basement membrane precedes most glomerular diseases. However, little is known about the regulation of podocyte adhesion in vivo. Thus, we systematically screened for podocyte-specific focal adhesome (FA) components, using genetic reporter models in combination with iTRAQ-based mass spectrometry. This approach led to the identification of FERM domain protein EPB41L5 as a highly enriched podocyte-specific FA component in vivo. Genetic deletion of Epb41l5 resulted in severe proteinuria, detachment of podocytes, and development of focal segmental glomerulosclerosis. Remarkably, by binding and recruiting the RhoGEF ARGHEF18 to the leading edge, EPB41L5 directly controls actomyosin contractility and subsequent maturation of focal adhesions, cell spreading, and migration. Furthermore, EPB41L5 controls matrix-dependent outside-in signaling by regulating the focal adhesome composition. Thus, by linking extracellular matrix sensing and signaling, focal adhesion maturation, and actomyosin activation EPB41L5 ensures the mechanical stability required for podocytes at the kidney filtration barrier. Finally, a diminution of EPB41L5-dependent signaling programs appears to be a common theme of podocyte disease, and therefore offers unexpected interventional therapeutic strategies to prevent podocyte loss and kidney disease progression.
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Siegerist F, Blumenthal A, Zhou W, Endlich K, Endlich N. Acute podocyte injury is not a stimulus for podocytes to migrate along the glomerular basement membrane in zebrafish larvae. Sci Rep 2017; 7:43655. [PMID: 28252672 PMCID: PMC5333633 DOI: 10.1038/srep43655] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 01/26/2017] [Indexed: 12/28/2022] Open
Abstract
Podocytes have a unique 3D structure of major and interdigitating foot processes which is the prerequisite for renal blood filtration. Loss of podocytes leads to chronic kidney disease ending in end stage renal disease. Until now, the question if podocytes can be replaced by immigration of cells along the glomerular basement membrane (GBM) is under debate. We recently showed that in contrast to former theories, podocytes are stationary in the zebrafish pronephros and neither migrate nor change their branching pattern of major processes over 23 hours. However, it was still unclear whether podocytes are able to migrate during acute injury. To investigate this, we applied the nitroreductase/metronidazole zebrafish model of podocyte injury to in vivo two-photon microscopy. The application of metronidazole led to retractions of major processes associated with a reduced expression of podocyte-specific proteins and a formation of subpodocyte pseudocyst. Electron microscopy showed that broad areas of the capillaries became denuded. By 4D in vivo observation of single podocytes, we could show that the remaining podocytes did not walk along GBM during 24 h. This in vivo study reveals that podocytes are very stationary cells making regenerative processes by podocyte walking along the GBM very unlikely.
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Affiliation(s)
- Florian Siegerist
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Antje Blumenthal
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Weibin Zhou
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, USA
| | - Karlhans Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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Kriz W, Lemley KV. Mechanical challenges to the glomerular filtration barrier: adaptations and pathway to sclerosis. Pediatr Nephrol 2017; 32:405-417. [PMID: 27008645 DOI: 10.1007/s00467-016-3358-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 02/03/2016] [Accepted: 02/04/2016] [Indexed: 11/30/2022]
Abstract
Podocytes are lost as viable cells by detachment from the glomerular basement membrane (GBM), possibly due to factors such as pressure and filtrate flow. Distension of glomerular capillaries in response to increased pressure is limited by the elastic resistance of the GBM. The endothelium and podocytes adapt to changes in GBM area. The slit diaphragm (SD) seems to adjust by shuttling SD components between the SD and the adjacent foot processes (FPs), resulting in changes in SD area that parallel those in perfusion pressure.Filtrate flow tends to drag podocytes towards the urinary orifice by shear forces, which are highest within the filtration slits. The SD represents an atypical adherens junction, mechanically interconnecting the cytoskeleton of opposing FPs and tending to balance the shear forces.If under pathological conditions, increased filtrate flows locally overtax the attachment of FPs, the SDs are replaced by occluding junctions that seal the slits and the attachment of podocytes to the GBM is reinforced by FP effacement. Failure of these temporary adaptive mechanisms results in a steady process of podocyte detachment due to uncontrolled filtrate flows through bare areas of the GBM and, subsequently, the labyrinthine subpodocyte spaces, presenting as pseudocysts. In our view, shear stress due to filtrate flow-not capillary hydrostatic pressure-is the major challenge to the attachment of podocytes to the GBM.
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Affiliation(s)
- Wilhelm Kriz
- Department of Neuroanatomy, Medical Faculty Mannheim, University of Heidelberg, Ludolf-Krehl-Str. 13-17, 68167, Mannheim, Germany.
| | - Kevin V Lemley
- Division of Nephrology, Children's Hospital Los Angeles, Los Angeles, CA, USA
- Department of Pediatrics, University of Southern California Keck School of Medicine, Los Angeles, CA, USA
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Dai H, Liu Q, Liu B. Research Progress on Mechanism of Podocyte Depletion in Diabetic Nephropathy. J Diabetes Res 2017; 2017:2615286. [PMID: 28791309 PMCID: PMC5534294 DOI: 10.1155/2017/2615286] [Citation(s) in RCA: 170] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 02/05/2017] [Accepted: 03/05/2017] [Indexed: 12/13/2022] Open
Abstract
Diabetic nephropathy (DN) together with glomerular hyperfiltration has been implicated in the development of diabetic microangiopathy in the initial stage of diabetic diseases. Increased amounts of urinary protein in DN may be associated with functional and morphological alterations of podocyte, mainly including podocyte hypertrophy, epithelial-mesenchymal transdifferentiation (EMT), podocyte detachment, and podocyte apoptosis. Accumulating studies have revealed that disruption in multiple renal signaling pathways had been critical in the progression of these pathological damages, such as adenosine monophosphate-activated kinase signaling pathways (AMPK), wnt/β-catenin signaling pathways, endoplasmic reticulum stress-related signaling pathways, mammalian target of rapamycin (mTOR)/autophagy pathway, and Rho GTPases. In this review, we highlight new molecular insights underlying podocyte injury in the progression of DN, which offer new therapeutic targets to develop important renoprotective treatments for DN over the next decade.
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Affiliation(s)
- Haoran Dai
- Department of Nephrology, Shunyi Branch, Beijing Hospital of Traditional Chinese Medicine, Station East 5, Shunyi District, Beijing 101300, China
| | - Qingquan Liu
- Department of Nephrology, Shunyi Branch, Beijing Hospital of Traditional Chinese Medicine, Station East 5, Shunyi District, Beijing 101300, China
- Beijing Hospital of Traditional Chinese Medicine Affiliated to Capital Medical University, 23 Meishuguanhou Street, Dongcheng District, Beijing 100010, China
- *Qingquan Liu: and
| | - Baoli Liu
- Department of Nephrology, Shunyi Branch, Beijing Hospital of Traditional Chinese Medicine, Station East 5, Shunyi District, Beijing 101300, China
- Beijing Hospital of Traditional Chinese Medicine Affiliated to Capital Medical University, 23 Meishuguanhou Street, Dongcheng District, Beijing 100010, China
- *Baoli Liu:
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Abstract
Genetic studies of hereditary forms of nephrotic syndrome have identified several proteins that are involved in regulating the permselective properties of the glomerular filtration system. Further extensive research has elucidated the complex molecular basis of the glomerular filtration barrier and clearly established the pivotal role of podocytes in the pathophysiology of glomerular diseases. Podocyte architecture is centred on focal adhesions and slit diaphragms - multiprotein signalling hubs that regulate cell morphology and function. A highly interconnected actin cytoskeleton enables podocytes to adapt in order to accommodate environmental changes and maintain an intact glomerular filtration barrier. Actin-based endocytosis has now emerged as a regulator of podocyte integrity, providing an impetus for understanding the precise mechanisms that underlie the steady-state control of focal adhesion and slit diaphragm components. This Review outlines the role of actin dynamics and endocytosis in podocyte biology, and discusses how molecular heterogeneity in glomerular disorders could be exploited to deliver more rational therapeutic interventions, paving the way for targeted medicine in nephrology.
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Anti-TGF-β Antibody, 1D11, Ameliorates Glomerular Fibrosis in Mouse Models after the Onset of Proteinuria. PLoS One 2016; 11:e0155534. [PMID: 27187580 PMCID: PMC4871338 DOI: 10.1371/journal.pone.0155534] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 04/29/2016] [Indexed: 12/20/2022] Open
Abstract
Fibrosis is a final common pathway leading to loss of kidney function, in which the fibrogenic cytokine, transforming growth factor β (TGF-β), plays a central role. While previous studies showed that TGF-β antagonism by various means prevents fibrosis in mouse models, clinical approaches based on these findings remain elusive. 1D11 is a neutralizing antibody to all three isoforms of TGF-β. In both adriamycin (ADR)-induced nephropathy and NEP25 podocyte ablation nephropathy, thrice-weekly intraperitoneal administration of 1D11 from the day of disease induction until the mice were sacrificed (day 14 for ADR and day 28 for NEP25), significantly reduced glomerular COL1A2 mRNA accumulation and histological changes. Consistent with our previous findings, proteinuria remained overt in the mice treated with 1D11, suggesting distinct mechanisms for proteinuria and fibrogenesis. Podocyte numbers determined by WT1 staining were significantly reduced in NEP25-model glomeruli as expected, while WT1-positive cells were preserved in mice receiving 1D11. Even when 1D11 was administered after the onset of proteinuria on day 3, 1D11 preserved WT1-positive cell numbers in glomeruli and significantly reduced glomerular scar score (2.5 ± 0.2 [control IgG] vs. 1.8 ± 0.2 [1D11], P < 0.05) and glomerular COL1A2 mRNA expression (19.3 ± 4.4 [control IgG] vs. 8.4 ± 2.4 [1D11] fold increase over the healthy control, P < 0.05). Transmission electron microscopy revealed loss of podocytes and denuded glomerular basement membrane in NEP25 mice with disease, whereas podocytes remained attached to the basement membrane, though effaced and swollen, in those receiving 1D11 from day 3. Together, these data suggest that TGF-β neutralization by 1D11 prevents glomerular fibrosis even when started after the onset of proteinuria. While overt proteinuria and podocyte effacement persist, 1D11 prevents total podocytes detachment, which might be a key event activating fibrogenic events in glomeruli.
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Miziołek B, Bergler-Czop B, Stańkowska A, Brzezińska-Wcisło L. The safety of isotretinoin in patients with lupus nephritis: a comprehensive review. Cutan Ocul Toxicol 2016; 36:77-84. [PMID: 27160965 DOI: 10.3109/15569527.2016.1169284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Oral isotretinoin (13-cis-retinoinc acid) is a derivative of vitamin A and belongs to the first generation of retinoids, which act as synthetic isomers of retinoic acid (RA). It is a very effective agent in a treatment of acne vulgaris; however, multiple side effects related to therapy with retinoids preclude the use of isotretinoin in less severe acne vulgaris. A significant limitation for the administration of isotretinoin appears in case of concomitant kidney disease with a special attention regarding the safety of the agent in patients with lupus nephritis (LN). The aim of this review is an assessment of the safety of isotretinoin for the treatment of acne vulgaris in patients with LN. We searched both MEDLINE and SCOPUS databases, as well as several dermatological textbooks, to present all limitations and benefits of therapy with isotretinoin or its isomer (ATRA) for patients with kidney diseases. Several mouse models of SLE revealed a significant modulatory influence of retinoids on autoimmune injury of the glomerular unit. Retinoids were demonstrated to affect mononuclear cell infiltrations of renal tissue allowing for a reduction in the overall glomerular damage. Presumptively, they can affect a synthesis of autoantibodies significantly limiting their deposition in the glomerular unit. Moreover, retinoids were also shown to affect the synthesis of different cytokines specific both for lymphocytes Th1 (IL-2, IL-12, INFγ) ant Th2 (IL-4, IL-10). The influence of retinoids on the course of LN seems to be more multidimensional than only restricted to immune aspects and these synthetic RA isomers manifest also antiproteinuric activity in comparable extent to steroidal agents. The agents were demonstrated to counteract a loss of podocytes after the injury of the glomerular unit. They can promote a differentiation of renal progenitor cells (RPCs) within the Bowman capsule into mature podocytes leading to regeneration of podocyte number. Additionally, retinoids can probably protect podocytes from injury limiting their apoptosis, as well as reducing foot process effacement. Although, an endogenous production of RA isomers increases after the injury of the glomerular unit aiming to the restoration of podocyte number, it can be significantly impaired by a loss of albumins into urine. RA isomers are progressively sequestered by albumin within the Bowman's space and therefore, they are quickly eliminated with urine. It was demonstrated that the administration of exogenous RA isomers (retinoids) can bypass the activity of albumins enhancing the regeneration of podocytes. Finally, retinoids can regulate the production of vasoactive substances influencing on different vascular functions in the kidney. They can beneficially change a balance of angiotensin metabolites through by down-regulation of angiotensin-converting enzyme type 1 and the enhancement of an expression of angiotensin-converting enzyme type 2. Another studies revealed that retinoids could also alter the activity of renal endothelin pathway; however, the significance of this effect requires further elucidation. Taken all these presented effects of retinoids in the kidney into consideration, we can conclude that isotretinoin can be the safe treatment option of acne vulgaris in patients with LN.
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Affiliation(s)
- Bartosz Miziołek
- b Department of Dermatology , Andrzej Mielęcki Silesian Independent Public Clinical Hospital in Katowice , Katowice , Poland
| | - Beata Bergler-Czop
- a Department of Dermatology , School of Medicine in Katowice, Medical University of Silesia in Katowice , Katowice , Poland and
| | - Anna Stańkowska
- b Department of Dermatology , Andrzej Mielęcki Silesian Independent Public Clinical Hospital in Katowice , Katowice , Poland
| | - Ligia Brzezińska-Wcisło
- a Department of Dermatology , School of Medicine in Katowice, Medical University of Silesia in Katowice , Katowice , Poland and
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Secondary Focal Segmental Glomerulosclerosis: From Podocyte Injury to Glomerulosclerosis. BIOMED RESEARCH INTERNATIONAL 2016; 2016:1630365. [PMID: 27088082 PMCID: PMC4819087 DOI: 10.1155/2016/1630365] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2015] [Accepted: 03/10/2016] [Indexed: 11/18/2022]
Abstract
Focal segmental glomerulosclerosis (FSGS) is a common cause of proteinuria and nephrotic syndrome leading to end stage renal disease (ESRD). There are two types of FSGS, primary (idiopathic) and secondary forms. Secondary FSGS shows less severe clinical features compared to those of the primary one. However, secondary FSGS has an important clinical significance because a variety of renal diseases progress to ESRD thorough the form of secondary FSGS. The defining feature of FSGS is proteinuria. The key event of FSGS is podocyte injury which is caused by multiple factors. Unanswered questions about how these factors act on podocytes to cause secondary FSGS are various and ill-defined. In this review, we provide brief overview and new insights into FSGS, podocyte injury, and their potential linkage suggesting clues to answer for treatment of the disease.
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Nagata M. Podocyte injury and its consequences. Kidney Int 2016; 89:1221-30. [PMID: 27165817 DOI: 10.1016/j.kint.2016.01.012] [Citation(s) in RCA: 321] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 12/12/2015] [Accepted: 01/27/2016] [Indexed: 01/02/2023]
Abstract
Podocytes maintain the glomerular filtration barrier, and the stability of this barrier depends on their highly differentiated postmitotic phenotype, which also defines the particular vulnerability of the glomerulus. Recent podocyte biology and gene disruption studies in vivo indicate a causal relationship between abnormalities of single podocyte molecules and proteinuria and glomerulosclerosis. Podocytes live under various stresses and pathological stimuli. They adapt to maintain homeostasis, but excessive stress leads to maladaptation with complex biological changes including loss of integrity and dysregulation of cellular metabolism. Podocyte injury causes proteinuria and detachment from the glomerular basement membrane. In addition to "sick" podocytes and their detachment, our understanding of glomerular responses following podocyte loss needs to address the pathways from podocyte injury to sclerosis. Studies have found a variety of glomerular responses to podocyte dysfunction in vivo, such as disruption of podocyte-endothelial cross talk and activation of podocyte-parietal cell interactions, all of which help us to understand the complex scenario of podocyte injury and its consequences. This review focuses on the cellular aspects of podocyte dysfunction and the adaptive or maladaptive glomerular responses to podocyte injury that lead to its major consequence, glomerulosclerosis.
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Affiliation(s)
- Michio Nagata
- Kidney and Vascular Pathology, University of Tsukuba, Ibaraki, Japan.
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Lewko B, Welsh GI, Jankowski M. Editorial: Podocyte Pathology and Nephropathy. Front Endocrinol (Lausanne) 2015; 6:145. [PMID: 26441835 PMCID: PMC4585015 DOI: 10.3389/fendo.2015.00145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/02/2015] [Indexed: 11/13/2022] Open
Affiliation(s)
- Barbara Lewko
- Department of Pathophysiology, Faculty of Pharmacy, Medical University of Gdansk, Gdansk, Poland
- Laboratory of Molecular and Cellular Nephrology Gdansk, Miroslaw Mossakowski Medical Research Center of the Polish Academy of Sciences, Warsaw, Poland
- *Correspondence: Barbara Lewko,
| | | | - Maciej Jankowski
- Laboratory of Molecular and Cellular Nephrology Gdansk, Miroslaw Mossakowski Medical Research Center of the Polish Academy of Sciences, Warsaw, Poland
- Department of Clinical Chemistry, Medical University of Gdansk, Gdansk, Poland
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