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Farhat I, Maréchal E, Calmo D, Ansart M, Paindavoine M, Bard P, Tarris G, Ducloux D, Felix SA, Martin L, Tinel C, Gibier JB, Funes de la Vega M, Rebibou JM, Bamoulid J, Legendre M. Recognition of intraglomerular histological features with deep learning in protocol transplant biopsies and their association with kidney function and prognosis. Clin Kidney J 2024; 17:sfae019. [PMID: 38370429 PMCID: PMC10873504 DOI: 10.1093/ckj/sfae019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Indexed: 02/20/2024] Open
Abstract
Background The Banff Classification may not adequately address protocol transplant biopsies categorized as normal in patients experiencing unexplained graft function deterioration. This study seeks to employ convolutional neural networks to automate the segmentation of glomerular cells and capillaries and assess their correlation with transplant function. Methods A total of 215 patients were categorized into three groups. In the Training cohort, glomerular cells and capillaries from 37 patients were manually annotated to train the networks. The Test cohort (24 patients) compared manual annotations vs automated predictions, while the Application cohort (154 protocol transplant biopsies) examined predicted factors in relation to kidney function and prognosis. Results In the Test cohort, the networks recognized histological structures with Precision, Recall, F-score and Intersection Over Union exceeding 0.92, 0.85, 0.89 and 0.74, respectively. Univariate analysis revealed associations between the estimated glomerular filtration rate (eGFR) at biopsy and relative endothelial area (r = 0.19, P = .027), endothelial cell density (r = 0.20, P = .017), mean parietal epithelial cell area (r = -0.38, P < .001), parietal epithelial cell density (r = 0.29, P < .001) and mesangial cell density (r = 0.22, P = .010). Multivariate analysis retained only endothelial cell density as associated with eGFR (Beta = 0.13, P = .040). Endothelial cell density (r = -0.22, P = .010) and mean podocyte area (r = 0.21, P = .016) were linked to proteinuria at biopsy. Over 44 ± 29 months, 25 patients (16%) reached the primary composite endpoint (dialysis initiation, or 30% eGFR sustained decline), with relative endothelial area, mean endothelial cell area and parietal epithelial cell density below medians linked to this endpoint [hazard ratios, respectively, of 2.63 (P = .048), 2.60 (P = .039) and 3.23 (P = .019)]. Conclusion This study automated the measurement of intraglomerular cells and capillaries. Our results suggest that the precise segmentation of endothelial and epithelial cells may serve as a potential future marker for the risk of graft loss.
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Affiliation(s)
- Imane Farhat
- Department of Nephrology, CHU Dijon, Dijon, France
| | | | - Doris Calmo
- Department of Nephrology, CHU Besançon, Besançon, France
| | - Manon Ansart
- LEAD-CNRS, UMR 5022, Université de Bourgogne, Dijon, France
| | | | - Patrick Bard
- LEAD-CNRS, UMR 5022, Université de Bourgogne, Dijon, France
| | | | - Didier Ducloux
- Department of Nephrology, CHU Besançon, Besançon, France
- Etablissement Français du sang, Besançon, France
| | | | | | - Claire Tinel
- Department of Nephrology, CHU Dijon, Dijon, France
- Etablissement Français du sang, Besançon, France
| | | | | | - Jean-Michel Rebibou
- Department of Nephrology, CHU Dijon, Dijon, France
- Etablissement Français du sang, Besançon, France
| | - Jamal Bamoulid
- Department of Nephrology, CHU Besançon, Besançon, France
- Etablissement Français du sang, Besançon, France
| | - Mathieu Legendre
- Department of Nephrology, CHU Dijon, Dijon, France
- LEAD-CNRS, UMR 5022, Université de Bourgogne, Dijon, France
- Etablissement Français du sang, Besançon, France
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2
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Ceol M, Gianesello L, Trimarchi H, Migliorini A, Priante G, Radu CM, Naso E, Angelini A, Calò LA, Anglani F, Del Prete D. Human parietal epithelial cells (PECs) and proteinuria in lupus nephritis: a role for ClC-5, megalin, and cubilin? J Nephrol 2023; 36:2499-2506. [PMID: 37594671 PMCID: PMC10703968 DOI: 10.1007/s40620-023-01725-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 06/30/2023] [Indexed: 08/19/2023]
Abstract
BACKGROUND Parietal epithelial cells are a heterogeneous population of cells located on Bowman's capsule. These cells are known to internalize albumin with a still undetermined mechanism, although albumin has been shown to induce phenotypic changes in parietal epithelial cells. Proximal tubular cells are the main actors in albumin handling via the macromolecular complex composed by ClC-5, megalin, and cubilin. This study investigated the role of ClC-5, megalin, and cubilin in the parietal epithelial cells of kidney biopsies from proteinuric lupus nephritis patients and control subjects and identified phenotypical changes occurring in the pathological milieu. METHODS Immunohistochemistry and immunofluorescence analyses for ClC-5, megalin, cubilin, ANXA3, podocalyxin, CD24, CD44, HSA, and LTA marker were performed on 23 kidney biopsies from patients with Lupus Nephritis and 9 control biopsies (obtained from nephrectomies for renal cancer). RESULTS Two sub-populations of hypertrophic parietal epithelial cells ANXA3+/Podocalyxin-/CD44-, both expressing ClC-5, megalin, and cubilin and located at the tubular pole, were identified and characterized: the first one, CD24+/HSA-/LTA- had characteristics of human adult parietal epithelial multipotent progenitors, the second one, CD24-/LTA+/HSA+ committed to become phenotypically proximal tubular cells. The number of glomeruli presenting hypertrophic parietal epithelial cells positive for ClC-5, megalin, and cubilin were significantly higher in lupus nephritis patients than in controls. CONCLUSIONS Our results may provide further insight into the role of hypertrophic parietal epithelial cells located at the tubular pole and their possible involvement in protein endocytosis in lupus nephritis patients. These data also suggest that the presence of hypertrophic parietal epithelial cells in Bowman's capsule represents a potential resource for responding to protein overload observed in other glomerulonephritis.
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Affiliation(s)
- Monica Ceol
- Nephrology Unit- Kidney Histomorphology and Molecular Biology Laboratory, Department of Medicine-DIMED, University of Padua, Via Giustiniani, 2, 235128, Padua, Italy
| | - Lisa Gianesello
- Nephrology Unit- Kidney Histomorphology and Molecular Biology Laboratory, Department of Medicine-DIMED, University of Padua, Via Giustiniani, 2, 235128, Padua, Italy
| | - Hernan Trimarchi
- Nephrology Service, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Alberto Migliorini
- Nephrology Unit- Kidney Histomorphology and Molecular Biology Laboratory, Department of Medicine-DIMED, University of Padua, Via Giustiniani, 2, 235128, Padua, Italy
| | - Giovanna Priante
- Nephrology Unit- Kidney Histomorphology and Molecular Biology Laboratory, Department of Medicine-DIMED, University of Padua, Via Giustiniani, 2, 235128, Padua, Italy
| | - Claudia M Radu
- General Internal Medicine and Thrombotic and Hemorrhagic Diseases Unit, Department of Medicine, University of Padua, Padua, Italy
| | - Elena Naso
- Nephrology Unit- Kidney Histomorphology and Molecular Biology Laboratory, Department of Medicine-DIMED, University of Padua, Via Giustiniani, 2, 235128, Padua, Italy
| | - Annalisa Angelini
- Cardiovascular Pathology and Pathological Anatomy, Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padua, Padua, Italy
| | - Lorenzo A Calò
- Nephrology Unit- Kidney Histomorphology and Molecular Biology Laboratory, Department of Medicine-DIMED, University of Padua, Via Giustiniani, 2, 235128, Padua, Italy
| | - Franca Anglani
- Nephrology Unit- Kidney Histomorphology and Molecular Biology Laboratory, Department of Medicine-DIMED, University of Padua, Via Giustiniani, 2, 235128, Padua, Italy
| | - Dorella Del Prete
- Nephrology Unit- Kidney Histomorphology and Molecular Biology Laboratory, Department of Medicine-DIMED, University of Padua, Via Giustiniani, 2, 235128, Padua, Italy.
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3
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Parietal epithelial cell dysfunction in crescentic glomerulonephritis. Cell Tissue Res 2021; 385:345-354. [PMID: 34453566 PMCID: PMC8523405 DOI: 10.1007/s00441-021-03513-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 07/15/2021] [Indexed: 12/12/2022]
Abstract
Crescentic glomerulonephritis represents a group of kidney diseases characterized by rapid loss of kidney function and the formation of glomerular crescents. While the role of the immune system has been extensively studied in relation to the development of crescents, recent findings show that parietal epithelial cells play a key role in the pathophysiology of crescent formation, even in the absence of immune modulation. This review highlights our current understanding of parietal epithelial cell biology and the reported physiological and pathological roles that these cells play in glomerular lesion formation, especially in the context of crescentic glomerulonephritis.
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Kawaguchi T, Hasegawa K, Yasuda I, Muraoka H, Umino H, Tokuyama H, Hashiguchi A, Wakino S, Itoh H. Diabetic condition induces hypertrophy and vacuolization in glomerular parietal epithelial cells. Sci Rep 2021; 11:1515. [PMID: 33452384 PMCID: PMC7810998 DOI: 10.1038/s41598-021-81027-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 12/09/2020] [Indexed: 01/29/2023] Open
Abstract
Diabetic nephropathy (DN) is accompanied by characteristic changes in the glomerulus, but little is known about the effect of diabetes on parietal epithelial cells (PECs). In this study, a descriptive analysis of PECs was undertaken in diabetic db/db mice and in diabetic patients. PEC hypertrophy was significantly more prominent in diabetic mice than in nondiabetic mice, and this was evident even at the early stage. Additionally, the number of vacuoles in PECs was markedly increased in diabetic mice, suggesting the presence of cellular injury in PECs in DN. Although rare, binuclear cells were observed in mice with early diabetes. In cultured PECs, a high glucose condition, compared with normal glucose condition, induced cellular hypertrophy and apoptosis. Flow cytometry showed that some PECs in the G0 phase reentered the cell cycle but got arrested in the S phase. Finally, in human diabetic subjects, hypertrophy and vacuolization were observed in the PECs. Our data showed that PECs undergo substantial changes in DN and may participate in rearrangement for differentiation into podocytes.
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Affiliation(s)
- Takahisa Kawaguchi
- grid.26091.3c0000 0004 1936 9959Department of Internal Medicine, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582 Japan
| | - Kazuhiro Hasegawa
- grid.26091.3c0000 0004 1936 9959Department of Internal Medicine, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582 Japan
| | - Itaru Yasuda
- grid.26091.3c0000 0004 1936 9959Department of Internal Medicine, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582 Japan
| | - Hirokazu Muraoka
- grid.26091.3c0000 0004 1936 9959Department of Internal Medicine, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582 Japan
| | - Hiroyuki Umino
- grid.26091.3c0000 0004 1936 9959Department of Internal Medicine, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582 Japan
| | - Hirobumi Tokuyama
- grid.26091.3c0000 0004 1936 9959Department of Internal Medicine, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582 Japan
| | - Akinori Hashiguchi
- grid.26091.3c0000 0004 1936 9959Department of Pathology, School of Medicine, Keio University, Tokyo, 160-8582 Japan
| | - Shu Wakino
- grid.26091.3c0000 0004 1936 9959Department of Internal Medicine, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582 Japan
| | - Hiroshi Itoh
- grid.26091.3c0000 0004 1936 9959Department of Internal Medicine, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582 Japan
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5
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Bryniarski MA, Yee BM, Chaves LD, Stahura CM, Yacoub R, Morris ME. Megalin-mediated albumin endocytosis in cultured murine mesangial cells. Biochem Biophys Res Commun 2020; 529:740-746. [PMID: 32736701 DOI: 10.1016/j.bbrc.2020.05.166] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 05/22/2020] [Indexed: 12/25/2022]
Abstract
Endocytosis by podocytes is gaining increased attention as a biologic means of removing large proteins such as serum albumin from the glomerular barrier. Some of this function has been attributed to the megalin/cubilin (Lrp2/Cubn) receptor complex and the albumin recycling protein FcRn (Fcgrt). However, whether other glomerular cells possess the potential to perform this same phenomenon or express these proteins remains uncharacterized. Mesangial cells are uniquely positioned in glomeruli and represent a cell type capable of performing several diverse functions. Here, the expression of megalin and FcRn in murine mesangial cells along with the megalin adaptor protein Dab-2 (Dab2) was shown for the first time. Cubilin mRNA expression was detected, but the absence of the cubilin partner amnionless (Amn) suggested that cubilin is minimally functional, if at all, in these cells. Mesangial cell endocytosis of albumin was characterized and shown to involve a receptor-mediated process. Albumin endocytosis was significantly impaired (p < 0.01) under inducible megalin knockdown conditions in stably transduced mesangial cells. The current work provides both the novel identification of megalin and FcRn in mesangial cells and the functional demonstration of megalin-mediated albumin endocytosis.
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Affiliation(s)
- Mark A Bryniarski
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, 303 Pharmacy Building, Buffalo, NY, 14214, USA
| | - Benjamin M Yee
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, 303 Pharmacy Building, Buffalo, NY, 14214, USA
| | - Lee D Chaves
- Department of Internal Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, 875 Ellicott St, Buffalo, NY, 14214, USA
| | - Corrine M Stahura
- Department of Internal Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, 875 Ellicott St, Buffalo, NY, 14214, USA
| | - Rabi Yacoub
- Department of Internal Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, 875 Ellicott St, Buffalo, NY, 14214, USA
| | - Marilyn E Morris
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, 303 Pharmacy Building, Buffalo, NY, 14214, USA.
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Kwiatkowska E, Stefańska K, Zieliński M, Sakowska J, Jankowiak M, Trzonkowski P, Marek-Trzonkowska N, Kwiatkowski S. Podocytes-The Most Vulnerable Renal Cells in Preeclampsia. Int J Mol Sci 2020; 21:ijms21145051. [PMID: 32708979 PMCID: PMC7403979 DOI: 10.3390/ijms21145051] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/14/2020] [Accepted: 07/14/2020] [Indexed: 12/24/2022] Open
Abstract
Preeclampsia (PE) is a disorder that affects 3–5% of normal pregnancies. It was believed for a long time that the kidney, similarly to all vessels in the whole system, only sustained endothelial damage. The current knowledge gives rise to a presumption that the main role in the development of proteinuria is played by damage to the podocytes and their slit diaphragm. The podocyte damage mechanism in preeclampsia is connected to free VEGF and nitric oxide (NO) deficiency, and an increased concentration of endothelin-1 and oxidative stress. From national cohort studies, we know that women who had preeclampsia in at least one pregnancy carried five times the risk of developing end-stage renal disease (ESRD) when compared to women with physiological pregnancies. The focal segmental glomerulosclerosis (FSGS) is the dominant histopathological lesion in women with a history of PE. The kidney’s podocytes are not subject to replacement or proliferation. Podocyte depletion exceeding 20% resulted in FSGS, which is a reason for the later development of ESRD. In this review, we present the mechanism of kidney (especially podocytes) injury in preeclampsia. We try to explain how this damage affects further changes in the morphology and function of the kidneys after pregnancy.
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Affiliation(s)
- Ewa Kwiatkowska
- Clinical Department of Nephrology, Transplantology and Internal Medicine, Pomeranian Medical University, 70-111 Szczecin, Poland;
| | - Katarzyna Stefańska
- Department of Obstetrics, Medical University of Gdańsk, 80-210 Gdańsk, Poland
- Correspondence:
| | - Maciej Zieliński
- Department of Medical Immunology, Medical University of Gdańsk, 80-210 Gdańsk, Poland; (M.Z.); (J.S.); (M.J.); (P.T.)
| | - Justyna Sakowska
- Department of Medical Immunology, Medical University of Gdańsk, 80-210 Gdańsk, Poland; (M.Z.); (J.S.); (M.J.); (P.T.)
| | - Martyna Jankowiak
- Department of Medical Immunology, Medical University of Gdańsk, 80-210 Gdańsk, Poland; (M.Z.); (J.S.); (M.J.); (P.T.)
| | - Piotr Trzonkowski
- Department of Medical Immunology, Medical University of Gdańsk, 80-210 Gdańsk, Poland; (M.Z.); (J.S.); (M.J.); (P.T.)
| | - Natalia Marek-Trzonkowska
- International Centre for Cancer Vaccine Science Cancer Immunology Group, University of Gdansk, 80-822 Gdańsk, Poland;
- Laboratory of Immunoregulation and Cellular Therapies, Department of Family Medicine, Medical University of Gdańsk, 80-210 Gdańsk, Poland
| | - Sebastian Kwiatkowski
- Department of Obstetrics and Gynecology, Pomeranian Medical University, 70-111 Szczecin, Poland;
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Kaverina NV, Eng DG, Freedman BS, Kutz JN, Chozinski TJ, Vaughan JC, Miner JH, Pippin JW, Shankland SJ. Dual lineage tracing shows that glomerular parietal epithelial cells can transdifferentiate toward the adult podocyte fate. Kidney Int 2019; 96:597-611. [PMID: 31200942 PMCID: PMC7008116 DOI: 10.1016/j.kint.2019.03.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 03/11/2019] [Accepted: 03/12/2019] [Indexed: 12/12/2022]
Abstract
Podocytes are differentiated post-mitotic cells that cannot replace themselves after injury. Glomerular parietal epithelial cells are proposed to be podocyte progenitors. To test whether a subset of parietal epithelial cells transdifferentiate to a podocyte fate, dual reporter PEC-rtTA|LC1|tdTomato|Nphs1-FLPo|FRT-EGFP mice, named PEC-PODO, were generated. Doxycycline administration permanently labeled parietal epithelial cells with tdTomato reporter (red), and upon doxycycline removal, the parietal epithelial cells (PECs) cannot label further. Despite the presence or absence of doxycycline, podocytes cannot label with tdTomato, but are constitutively labeled with an enhanced green fluorescent protein (EGFP) reporter (green). Only activation of the Nphs1-FLPo transgene by labeled parietal epithelial cells can generate a yellow color. At day 28 of experimental focal segmental glomerulosclerosis, podocyte density was 20% lower in 20% of glomeruli. At day 56 of experimental focal segmental glomerulosclerosis, podocyte density was 18% lower in 17% of glomeruli. TdTomato+ parietal epithelial cells were restricted to Bowman's capsule in healthy mice. However, by days 28 and 56 of experimental disease, two-thirds of tdTomato+ parietal epithelial cells within glomerular tufts were yellow in color. These cells co-expressed the podocyte markers podocin, nephrin, p57 and VEGF164, but not markers of endothelial (ERG) or mesangial (Perlecan) cells. Expansion microscopy showed primary, secondary and minor processes in tdTomato+EGFP+ cells in glomerular tufts. Thus, our studies provide strong evidence that parietal epithelial cells serve as a source of new podocytes in adult mice.
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Affiliation(s)
- Natalya V Kaverina
- Division of Nephrology, University of Washington, Seattle, Washington, USA
| | - Diana G Eng
- Division of Nephrology, University of Washington, Seattle, Washington, USA
| | | | - J Nathan Kutz
- Department of Applied Mathematics, University of Washington, Seattle, Washington, USA
| | - Tyler J Chozinski
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Joshua C Vaughan
- Department of Chemistry, University of Washington, Seattle, Washington, USA; Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA
| | - Jeffrey H Miner
- Division of Nephrology, Washington University School of Medicine, St Louis, Missouri, USA
| | - Jeffrey W Pippin
- Division of Nephrology, University of Washington, Seattle, Washington, USA
| | - Stuart J Shankland
- Division of Nephrology, University of Washington, Seattle, Washington, USA.
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8
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Gianesello L, Anglani F, Del Prete D. Protein uptake at glomerular level: is it just the work of podocytes? Nephrol Dial Transplant 2019; 35:1675-1677. [DOI: 10.1093/ndt/gfz127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Indexed: 11/14/2022] Open
Affiliation(s)
- Lisa Gianesello
- Clinical Nephrology Unit, Department of Medicine DIMED, Kidney Histomorphology and Molecular Biology Laboratory, University of Padua, Padua, Italy
| | - Franca Anglani
- Clinical Nephrology Unit, Department of Medicine DIMED, Kidney Histomorphology and Molecular Biology Laboratory, University of Padua, Padua, Italy
| | - Dorella Del Prete
- Clinical Nephrology Unit, Department of Medicine DIMED, Kidney Histomorphology and Molecular Biology Laboratory, University of Padua, Padua, Italy
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Role of albumin and its modifications in glomerular injury. Pflugers Arch 2017; 469:975-982. [PMID: 28735420 DOI: 10.1007/s00424-017-2029-4] [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] [Received: 07/03/2017] [Accepted: 07/05/2017] [Indexed: 02/06/2023]
Abstract
Albuminuria is both a characteristic hallmark and a known risk factor for progressive glomerular disease. Although the molecular basis for a potential causative role for albuminuria in progressive chronic kidney disease remains poorly understood, there have been several recent advances in our understanding of the role of albumin, and its molecular modifications, in the development and progression of glomerular disease. This review discusses recent findings related to the ability of albumin and its associated factors to directly induce podocyte and glomerular injury. Additional recent studies confirming the ability and mechanisms by which podocytes endocytose albumin are also discussed. Lastly, we present several known molecular modifications in the albumin molecule itself, as well as substances bound to it, which may be important and potentially clinically relevant mediators of albumin-induced glomerular injury. These recent findings may create entirely new opportunities to develop novel future therapies directed at albumin that could potentially help reduce podocyte and renal tubular injury and slow the progression of chronic glomerular disease.
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Abstract
In normal glomeruli, parietal epithelial cells (PECs) line the inside of Bowman's capsule and form an inconspicuous sheet of flat epithelial cells in continuity with the proximal tubular epithelial cells (PTECs) at the urinary pole and with the podocytes at the vascular pole. PECs, PTECs and podocytes have a common mesenchymal origin and are the result of divergent differentiation during embryogenesis. Podocytes and PTECs are highly differentiated cells with well-established functions pertaining to the maintenance of the filtration barrier and transport, respectively. For PECs, no specific function other than a structural one has been known until recently. Possible important functions for PECs in the fate of the glomerulus in glomerular disease have now become apparent: (1) PECs may be involved in the replacement of lost podocytes; (2) PECs form the basis of extracapillary proliferative lesions and subsequent sclerosis in glomerular disease. In addition to the acknowledgement that PECs are crucial in glomerular disease, knowledge has been gained regarding the molecular processes driving the phenotypic changes and behavior of PECs. Understanding these molecular processes is important for the development of specific therapeutic approaches aimed at either stimulation of the regenerative function of PECs or inhibition of the pro-sclerotic action of PECs. In this review, we discuss recent advances pertaining to the role of PECs in glomerular regeneration and disease and address the major molecular processes involved.
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Roeder SS, Barnes TJ, Lee JS, Kato I, Eng DG, Kaverina NV, Sunseri MW, Daniel C, Amann K, Pippin JW, Shankland SJ. Activated ERK1/2 increases CD44 in glomerular parietal epithelial cells leading to matrix expansion. Kidney Int 2016; 91:896-913. [PMID: 27998643 DOI: 10.1016/j.kint.2016.10.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 09/19/2016] [Accepted: 10/06/2016] [Indexed: 10/20/2022]
Abstract
The glycoprotein CD44 is barely detected in normal mouse and human glomeruli, but is increased in glomerular parietal epithelial cells following podocyte injury in focal segmental glomerulosclerosis (FSGS). To determine the biological role and regulation of CD44 in these cells, we employed an in vivo and in vitro approach. Experimental FSGS was induced in CD44 knockout and wild-type mice with a cytotoxic podocyte antibody. Albuminuria, focal and global glomerulosclerosis (periodic acid-Schiff stain), and collagen IV staining were lower in CD44 knockout compared with wild-type mice with FSGS. Parietal epithelial cells had lower migration from Bowman's capsule to the glomerular tuft in CD44 knockout mice with disease compared with wild type mice. In cultured murine parietal epithelial cells, overexpressing CD44 with a retroviral vector encoding CD44 was accompanied by significantly increased collagen IV expression and parietal epithelial cell migration. Because our results showed de novo co-staining for activated ERK1/2 (pERK) in parietal epithelial cells in experimental FSGS, and also in biopsies from patients with FSGS, two in vitro strategies were employed to prove that pERK regulated CD44 levels. First, mouse parietal epithelial cells were infected with a retroviral vector for the upstream kinase MEK-DD to increase pERK, which was accompanied by increased CD44 levels. Second, in CD44-overexpressing parietal epithelial cells, decreasing pERK with U0126 was accompanied by reduced CD44. Finally, parietal epithelial cell migration was higher in cells with increased and reduced in cells with decreased pERK. Thus, pERK is a regulator of CD44 expression, and increased CD44 expression leads to a pro-sclerotic and migratory parietal epithelial cell phenotype.
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Affiliation(s)
- Sebastian S Roeder
- Division of Nephrology, University of Washington, Seattle, Washington, USA; Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Taylor J Barnes
- Division of Nephrology, University of Washington, Seattle, Washington, USA; Department of Biology, Oregon State University, Corvallis, Oregon, USA
| | - Jonathan S Lee
- Division of Nephrology, University of Washington, Seattle, Washington, USA
| | - India Kato
- Division of Nephrology, University of Washington, Seattle, Washington, USA
| | - Diana G Eng
- Division of Nephrology, University of Washington, Seattle, Washington, USA
| | - Natalya V Kaverina
- Division of Nephrology, University of Washington, Seattle, Washington, USA
| | - Maria W Sunseri
- Division of Nephrology, University of Washington, Seattle, Washington, USA
| | - Christoph Daniel
- Department of Nephropathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Kerstin Amann
- Department of Nephropathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Jeffrey W Pippin
- Division of Nephrology, University of Washington, Seattle, Washington, USA
| | - Stuart J Shankland
- Division of Nephrology, University of Washington, Seattle, Washington, USA.
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Jia Y, Sun Y, Weng L, Li Y, Zhang Q, Zhou H, Yang B. Low molecular weight fucoidan protects renal tubular cells from injury induced by albumin overload. Sci Rep 2016; 6:31759. [PMID: 27545472 PMCID: PMC4992848 DOI: 10.1038/srep31759] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 07/27/2016] [Indexed: 12/02/2022] Open
Abstract
Albuminuria is a causative and aggravating factor for progressive renal damage in chronic kidney disease (CKD). The aim of this study was to determine if low molecular weight fucoidan (LMWF) could protect renal function and tubular cells from albumin overload caused injury. Treatment with 10 mg/g bovine serum albumin caused renal dysfunction, morphological changes, and overexpression of inflammation and fibrosis associated proteins in 129S2/Sv mice. LMWF (100 mg/kg) protected against kidney injury and renal dysfunction with decreased blood creatinine by 34% and urea nitrogen by 25%, increased creatinine clearance by 48%, and decreased significantly urinary albumin concentration. In vitro proximal tubule epithelial cell (NRK-52E) model showed that LMWF dose-dependently inhibited overexpression of proinflammatory and profibrotic factors, oxidative stress and apoptosis caused by albumin overload. These experimental results indicate that LMWF protects against albumin overload caused renal injury by inhibiting inflammation, fibrosis, oxidative stress and apoptosis, which suggests that LMWF could be a promising candidate drug for preventing CKD.
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Affiliation(s)
- Yingli Jia
- State Key Laboratory of Natural and Biomimetic Drugs, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Department of Pharmacology, School of Basic Medical Sciences, Peking University, 100191, P.R. China
| | - Yi Sun
- State Key Laboratory of Natural and Biomimetic Drugs, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Department of Pharmacology, School of Basic Medical Sciences, Peking University, 100191, P.R. China
| | - Lin Weng
- State Key Laboratory of Natural and Biomimetic Drugs, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Department of Pharmacology, School of Basic Medical Sciences, Peking University, 100191, P.R. China
| | - Yingjie Li
- State Key Laboratory of Natural and Biomimetic Drugs, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Department of Pharmacology, School of Basic Medical Sciences, Peking University, 100191, P.R. China
| | - Quanbin Zhang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, P.R. China
| | - Hong Zhou
- State Key Laboratory of Natural and Biomimetic Drugs, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Department of Pharmacology, School of Basic Medical Sciences, Peking University, 100191, P.R. China
| | - Baoxue Yang
- State Key Laboratory of Natural and Biomimetic Drugs, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Department of Pharmacology, School of Basic Medical Sciences, Peking University, 100191, P.R. China
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13
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Yamazaki T, Sasaki S, Okamoto T, Sato Y, Hayashi A, Ariga T. Up-Regulation of CD74 Expression in Parietal Epithelial Cells in a Mouse Model of Focal Segmental Glomerulosclerosis. Nephron Clin Pract 2016; 134:238-252. [PMID: 27463800 DOI: 10.1159/000448221] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 07/04/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS De novo expression of CD44 is considered as a marker of parietal epithelial cell (PEC) activation. The aim of our study was to explore CD74 expression, which can form a complex with CD44, in PECs during the progression of focal segmental glomerulosclerosis (FSGS). To clarify the role of CD74 expression and of its interaction with CD44, we generated a new mouse model with enhanced PEC activation through lipopolysaccharide (LPS) application to adriamycin (ADR)-induced nephropathy mice (LPS-treated ADR mice). METHODS As a new model, LPS was intraperitoneally injected into the mice 3 weeks after ADR injection. The mice were divided into 3 categories: control mice, ADR mice and LPS-treated ADR mice. Renal function parameters, histologic changes and immunohistochemical expression of CD74 and other PEC activation markers were analyzed after LPS application. RESULTS After LPS stimulation, the glomeruli were characterized by enlarged epithelial cells with strong CD74 expression, followed by pseudo-crescent formation. By double staining, CD74-positive enlarged cells showed co-expression of classical PEC markers, but not of Lotus tetragonolobus lectin (marker of proximal tubular cells), suggesting amplification of PEC activation. Time-course analysis displayed marked upregulation of CD74 expression during rapid PEC activation compared with CD44. Additionally, the time-dependent change in ERK phosphorylation showed a similar pattern to CD74. CONCLUSION Our results indicate that CD74 can be a marker for PEC activation in FSGS. By modifying the ADR mouse model through LPS treatment, we found that CD74 upregulation better reflects a rapid amplification of PEC activation than CD44 expression.
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Affiliation(s)
- Takeshi Yamazaki
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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14
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McNicholas BA, Eng DG, Lichtnekert J, Rabinowitz PS, Pippin JW, Shankland SJ. Reducing mTOR augments parietal epithelial cell density in a model of acute podocyte depletion and in aged kidneys. Am J Physiol Renal Physiol 2016; 311:F626-39. [PMID: 27440779 PMCID: PMC5142165 DOI: 10.1152/ajprenal.00196.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 07/12/2016] [Indexed: 02/06/2023] Open
Abstract
Parietal epithelial cell (PEC) response to glomerular injury may underlie a common pathway driving fibrogenesis following podocyte loss that typifies several glomerular disorders. Although the mammalian target of rapamycin (mTOR) pathway is important in cell homeostasis, little is known of the biological role or impact of reducing mTOR activity on PEC response following podocyte depletion, nor in the aging kidney. The purpose of these studies was to determine the impact on PECs of reducing mTOR activity following abrupt experimental depletion in podocyte number, as well as in a model of chronic podocyte loss and sclerosis associated with aging. Podocyte depletion was induced by an anti-podocyte antibody and rapamycin started at day 5 until death at day 14 Reducing mTOR did not lead to a greater reduction in podocyte density, despite greater glomerulosclerosis. However, mTOR inhibition lead to an increase in PEC density and PEC-derived crescent formation. Additionally, markers of epithelial-to-mesenchymal transition (platelet-derived growth factor receptor-β, α-smooth muscle actin, Notch-3) and PEC activation (CD44, collagen IV) were further increased by mTOR reduction. Aged mice treated with rapamycin for 1, 2, and 10 wk before death at 26.5 mo (≈75-yr-old human age) had increased the number of glomeruli with a crescentic appearance. mTOR inhibition at either a high or low level lead to changes in PEC phenotype, indicating PEC morphology is sensitive to changes mediated by global mTOR inhibition.
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Affiliation(s)
| | - Diana G Eng
- Division of Nephrology, University of Washington, Seattle, Washington; and
| | - Julia Lichtnekert
- Division of Nephrology, University of Washington, Seattle, Washington; and
| | | | - Jeffrey W Pippin
- Division of Nephrology, University of Washington, Seattle, Washington; and
| | - Stuart J Shankland
- Division of Nephrology, University of Washington, Seattle, Washington; and
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15
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Burlaka I, Nilsson LM, Scott L, Holtbäck U, Eklöf AC, Fogo AB, Brismar H, Aperia A. Prevention of apoptosis averts glomerular tubular disconnection and podocyte loss in proteinuric kidney disease. Kidney Int 2016; 90:135-48. [PMID: 27217195 PMCID: PMC6101029 DOI: 10.1016/j.kint.2016.03.026] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 02/19/2016] [Accepted: 03/10/2016] [Indexed: 01/09/2023]
Abstract
There is a great need for treatment that arrests progression of chronic kidney disease. Increased albumin in urine leads to apoptosis and fibrosis of podocytes and tubular cells and is a major cause of functional deterioration. There have been many attempts to target fibrosis, but because of the lack of appropriate agents, few have targeted apoptosis. Our group has described an ouabain-activated Na,K-ATPase/IP3R signalosome, which protects from apoptosis. Here we show that albumin uptake in primary rat renal epithelial cells is accompanied by a time- and dose-dependent mitochondrial accumulation of the apoptotic factor Bax, down-regulation of the antiapoptotic factor Bcl-xL and mitochondrial membrane depolarization. Ouabain opposes these effects and protects from apoptosis in albumin-exposed proximal tubule cells and podocytes. The efficacy of ouabain as an antiapoptotic and kidney-protective therapeutic tool was then tested in rats with passive Heymann nephritis, a model of proteinuric chronic kidney disease. Chronic ouabain treatment preserved renal function, protected from renal cortical apoptosis, up-regulated Bax, down-regulated Bcl-xL, and rescued from glomerular tubular disconnection and podocyte loss. Thus we have identified a novel clinically feasible therapeutic tool, which has the potential to protect from apoptosis and rescue from loss of functional tissue in chronic proteinuric kidney disease.
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Affiliation(s)
- Ievgeniia Burlaka
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
| | - Linnéa M Nilsson
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Solna, Sweden
| | - Lena Scott
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden.
| | - Ulla Holtbäck
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
| | - Ann-Christine Eklöf
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden
| | - Agnes B Fogo
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Hjalmar Brismar
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden; Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Solna, Sweden
| | - Anita Aperia
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden.
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16
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Roeder SS, Stefanska A, Eng DG, Kaverina N, Sunseri MW, McNicholas BA, Rabinovitch P, Engel FB, Daniel C, Amann K, Lichtnekert J, Pippin JW, Shankland SJ. Changes in glomerular parietal epithelial cells in mouse kidneys with advanced age. Am J Physiol Renal Physiol 2015; 309:F164-78. [PMID: 26017974 DOI: 10.1152/ajprenal.00144.2015] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 05/26/2015] [Indexed: 02/08/2023] Open
Abstract
Kidney aging is accompanied by characteristic changes in the glomerulus, but little is known about the effect of aging on glomerular parietal epithelial cells (PECs), nor if the characteristic glomerular changes in humans and rats also occur in very old mice. Accordingly, a descriptive analysis was undertaken in 27-mo-old C57B6 mice, considered advanced age. PEC density was significantly lower in older mice compared with young mice (aged 3 mo), and the decrease was more pronounced in juxtamedullary glomeruli compared with outer cortical glomeruli. In addition to segmental and global glomerulosclerosis in older mice, staining for matrix proteins collagen type IV and heparan sulfate proteoglycan were markedly increased in Bowman's capsules of older mouse glomeruli, consistent with increased extracellular matrix production by PECs. De novo staining for CD44, a marker of activated and profibrotic PECs, was significantly increased in aged glomeruli. CD44 staining was more pronounced in the juxtamedullary region and colocalized with phosphorylated ERK. Additionally, a subset of aged PECs de novo expressed the epithelial-to-mesenchymal transition markers α-smooth muscle and vimentin, with no changes in epithelial-to-mesenchymal transition markers E-cadherin and β-catenin. The mural cell markers neural/glial antigen 2, PDGF receptor-β, and CD146 as well as Notch 3 were also substantially increased in aged PECs. These data show that mice can be used to better understand the aging kidney and that PECs undergo substantial changes, especially in juxtamedullary glomeruli, that may participate in the overall decline in glomerular structure and function with advancing age.
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Affiliation(s)
- Sebastian S Roeder
- Division of Nephrology, University of Washington, Seattle, Washington; Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Ania Stefanska
- Division of Nephrology, University of Washington, Seattle, Washington
| | - Diana G Eng
- Division of Nephrology, University of Washington, Seattle, Washington
| | - Natalya Kaverina
- Division of Nephrology, University of Washington, Seattle, Washington
| | - Maria W Sunseri
- Division of Nephrology, University of Washington, Seattle, Washington
| | | | - Peter Rabinovitch
- Department of Pathology, University of Washington, Seattle, Washington
| | - Felix B Engel
- Department of Nephropathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany; and
| | - Christoph Daniel
- Department of Nephropathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany; and
| | - Kerstin Amann
- Department of Nephropathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany; and
| | - Julia Lichtnekert
- Division of Nephrology, University of Washington, Seattle, Washington
| | - Jeffrey W Pippin
- Division of Nephrology, University of Washington, Seattle, Washington
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17
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Glomerular parietal epithelial cells contribute to adult podocyte regeneration in experimental focal segmental glomerulosclerosis. Kidney Int 2015; 88:999-1012. [PMID: 25993321 PMCID: PMC4654724 DOI: 10.1038/ki.2015.152] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 04/01/2015] [Accepted: 04/02/2015] [Indexed: 01/02/2023]
Abstract
Since adult podocytes cannot adequately proliferate following depletion in disease states there has been interest in the potential role of progenitors in podocyte repair and regeneration. To determine if parietal epithelial cells (PECs) can serve as adult podocyte progenitors following disease-induced podocyte depletion, PECs were permanently labeled in adult PECrtTA/LC1/R26 reporter mice. In normal mice, labeled PECs were confined to Bowman's capsule, while in disease (cytotoxic sheep anti-podocyte antibody), labeled PECs were found in the glomerular tuft in progressively higher numbers by days 7, 14 and 28. Early in disease, the majority of PECs in the tuft co-expressed CD44. By day 28, when podocyte numbers were significantly higher and disease severity was significantly lower, the majority of labeled PECs co-expressed podocyte proteins but not CD44. Neither labeled PECs on the tuft, nor podocytes stained for the proliferation marker BrdU. The de novo expression of phospho-ERK colocalized to CD44 expressing PECs, but not to PECs expressing podocyte markers. Thus, in a mouse model of focal segmental glomerulosclerosis typified by abrupt podocyte depletion followed by regeneration, PECs undergo two phenotypic changes once they migrate to the glomerular tuft. Initially these cells are predominantly activated CD44 expressing cells coinciding with glomerulosclerosis, and later they predominantly exhibit a podocyte phenotype which is likely reparative.
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18
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Liu D, Xu M, Ding LH, Lv LL, Liu H, Ma KL, Zhang AH, Crowley SD, Liu BC. Activation of the Nlrp3 inflammasome by mitochondrial reactive oxygen species: a novel mechanism of albumin-induced tubulointerstitial inflammation. Int J Biochem Cell Biol 2014; 57:7-19. [PMID: 25281528 DOI: 10.1016/j.biocel.2014.09.018] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 08/30/2014] [Accepted: 09/16/2014] [Indexed: 01/22/2023]
Abstract
Albuminuria is not only an important marker of chronic kidney disease but also a crucial contributor to tubulointerstitial inflammation (TIF). In this study, we determined whether activation of the Nlrp3 inflammasome is involved in albuminuria induced-TIF and the underlying mechanisms of inflammasome activation by mitochondrial reactive oxygen species (mROS). We established an albumin-overload induced rat nephropathy model characterised by albuminuria, renal infiltration of inflammatory cells, tubular dilation and atrophy. The renal expression levels of the Nlrp3 inflammasome, IL-1β and IL-18 were significantly increased in this animal model. In vitro, albumin time- and dose-dependently increased the expression levels of the Nlrp3 inflammasome, IL-1β and IL18. Moreover, the silencing of the Nlrp3 gene or the use of the caspase-1 inhibitor Z-VAD-fmk significantly attenuated the albumin-induced increase in IL-1β and IL-18 expression in HK2 cells. In addition, mROS generation was elevated by albumin stimulation, whereas the ROS scavenger N-acetyl-l-cysteine (NAC) inhibited Nlrp3 expression and the release of IL-1β and IL-18. In kidney biopsy specimens obtained from patients with IgA nephropathy, Nlrp3 expression was localised to the proximal tubular epithelial cells, and this result is closely correlated with the extent of proteinuria and TIF. In summary, this study demonstrates that albuminuria may serve as an endogenous danger-associated molecular pattern (DAMP) that stimulates TIF via the mROS-mediated activation of the cytoplasmic Nlrp3 inflammasome.
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Affiliation(s)
- Dan Liu
- Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, Jiangsu, China
| | - Min Xu
- Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, Jiangsu, China
| | - Li-Hong Ding
- Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, Jiangsu, China
| | - Lin-Li Lv
- Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, Jiangsu, China
| | - Hong Liu
- Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, Jiangsu, China
| | - Kun-Ling Ma
- Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, Jiangsu, China
| | - Ai-Hua Zhang
- Institute of Pediatrics, Department of Nephrology, Nanjing Children's Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Steven D Crowley
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, NC, United States
| | - Bi-Cheng Liu
- Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, Jiangsu, China.
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19
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Glomerular parietal epithelial cells in kidney physiology, pathology, and repair. Curr Opin Nephrol Hypertens 2014; 22:302-9. [PMID: 23518463 DOI: 10.1097/mnh.0b013e32835fefd4] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE OF REVIEW We have summarized recently published glomerular parietal epithelial cell (PEC) research, focusing on their roles in glomerular development and physiology, and in certain glomerular diseases. The rationale is that PECs have been largely ignored until the recent availability of cell lineage tracing studies, human and murine PEC culture systems, and potential therapeutic interventions of PECs. RECENT FINDINGS Several new paradigms involving PECs have emerged demonstrating their significant contribution to glomerular physiology and numerous glomerular diseases. A subset of PECs serving as podocyte progenitors have been identified in normal human glomeruli. They provide a source for podocytes in adolescent mice, and their numbers increase in states of podocyte depletion. PEC progenitor number is increased by retinoids and angiotensin-converting enzyme inhibition. However, dysregulated growth of PEC progenitors leads to pseudo-crescent and crescent formation. In focal segmental glomerulosclerosis, considered a podocyte disease, activated PECs increase extracellular matrix production, which leads to synechial attachment and, when they move to the glomerular tuft, to segmental glomerulosclerosis. Finally, PECs might be adversely affected in proteinuric states by undergoing apoptosis. SUMMARY PECs play a critical role in glomerular repair through their progenitor function, but under certain circumstances paradoxically contribute to deterioration by augmenting scarring and crescent formation.
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20
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Jefferson JA, Shankland SJ. The pathogenesis of focal segmental glomerulosclerosis. Adv Chronic Kidney Dis 2014; 21:408-16. [PMID: 25168829 DOI: 10.1053/j.ackd.2014.05.009] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 05/30/2014] [Indexed: 01/13/2023]
Abstract
Focal segmental glomerulosclerosis (FSGS) is a histologic pattern of injury on kidney biopsy that can arise from a diverse range of causes and mechanisms. Although primary and secondary forms are described based on the underlying cause, there are many common factors that underlie the development of this segmental injury. In this review, we will describe the currently accepted model for the pathogenesis of classic FSGS and review the data supporting this model. Although the podocyte is considered the major target of injury in FSGS, we will also highlight the contributions of other resident glomerular cells in the development of FSGS.
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21
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Zhang D, Wei G, Li P, Zhou X, Zhang Y. Urine-derived stem cells: A novel and versatile progenitor source for cell-based therapy and regenerative medicine. Genes Dis 2014; 1:8-17. [PMID: 25411659 PMCID: PMC4234168 DOI: 10.1016/j.gendis.2014.07.001] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Engineered functional organs or tissues, created with autologous somatic cells and seeded on biodegradable or hydrogel scaffolds, have been developed for use in individuals with tissue damage suffered from congenital disorders, infection, irradiation, or cancer. However, in those patients, abnormal cells obtained by biopsy from the compromised tissue could potentially contaminate the engineered tissues. Thus, an alternative cell source for construction of the neo-organ or functional recovery of the injured or diseased tissues would be useful. Recently, we have found stem cells existing in the urine. These cells are highly expandable, and have self-renewal capacity, paracrine properties, and multi-differentiation potential. As a novel cell source, urine-derived stem cells (USCs) provide advantages for cell therapy and tissue engineering applications in regeneration of various tissues, particularly in the genitourinary tract, because they originate from the urinary tract system. Importantly, USCs can be obtained via a non-invasive, simple, and low-cost approach and induced with high efficiency to differentiate into three dermal cell lineages.
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Affiliation(s)
- Deying Zhang
- Department of Urology, Children's Hospital of Chongqing Medical University, Chongqing 400014, China ; Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27101, USA
| | - Guanghui Wei
- Department of Urology, Children's Hospital of Chongqing Medical University, Chongqing 400014, China
| | - Peng Li
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27101, USA ; Department of General Surgery, Affiliated Hospital of Nantong University, Nantong, China
| | - Xiaobo Zhou
- Center for Bioinformatics and Systems Biology, Department of Radiology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Yuanyuan Zhang
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27101, USA
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22
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Zhang J, Yanez D, Floege A, Lichtnekert J, Krofft RD, Liu ZH, Pippin JW, Shankland SJ. ACE-inhibition increases podocyte number in experimental glomerular disease independent of proliferation. J Renin Angiotensin Aldosterone Syst 2014; 16:234-48. [PMID: 25143333 PMCID: PMC4412792 DOI: 10.1177/1470320314543910] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Objective The objective of this article is to test the effects of angiotensin-converting enzyme (ACE)-inhibition on glomerular epithelial cell number in an inducible experimental model of focal segmental glomerulosclerosis (FSGS). Background Although ACE-inhibition has been shown to limit podocyte loss by enhancing survival, little is known about its effect on podocyte number following an abrupt decline in disease. Methods Experimental FSGS was induced with cytotoxic antipodocyte antibody. Following induction, groups were randomized to receive the ACE-inhibitor enalapril, the smooth muscle relaxant hydralazine (blood pressure control) or drinking water. Blood pressure, kidney function and histology were measured seven and 14 days following disease induction. Results Both glomerulosclerosis and urinary albumin-to-creatinine ratio were less in the ACE-inhibition arm at day 14. At day 7 of disease, mean podocyte numbers were 26% and 29% lower in the enalapril and hydralazine arms, respectively, compared to normal mice in which no antibody was injected. At day 14, the mean podocyte number was only 18% lower in the enalapril arm, but was 39% lower in the hydralazine arm compared to normal mice. Podocyte proliferation did not occur at any time in any group. Compared to water- or hydralazine-treated mice with FSGS, the enalapril arm had a higher mean number of glomerular parietal epithelial cells that co-expressed the podocyte proteins WT-1 and synaptopodin, as well as phospho-ERK. Conclusion The results show following an abrupt decline in podocyte number, the initiation of ACE-inhibition but not hydralazine, was accompanied by higher podocyte number in the absence of proliferation. This was accompanied by a higher number of parietal epithelial cells that co-express podocyte proteins. Increasing podocyte number appears to be accompanied by reduced glomerulosclerosis.
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Affiliation(s)
- Jiong Zhang
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Washington Current address: Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, China
| | - David Yanez
- Department of Biostatistics, School of Public Health, University of Washington, Washington
| | - Anna Floege
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Washington
| | - Julia Lichtnekert
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Washington
| | - Ronald D Krofft
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Washington
| | - Zhi-Hong Liu
- Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, China
| | - Jeffrey W Pippin
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Washington
| | - Stuart J Shankland
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Washington
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23
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Hamatani H, Hiromura K, Sakairi T, Takahashi S, Watanabe M, Maeshima A, Ohse T, Pippin JW, Shankland SJ, Nojima Y. Expression of a novel stress-inducible protein, sestrin 2, in rat glomerular parietal epithelial cells. Am J Physiol Renal Physiol 2014; 307:F708-17. [PMID: 25056347 DOI: 10.1152/ajprenal.00625.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Sestrin 2, initially identified as a p53 target protein, accumulates in cells exposed to stress and inhibits mammalian target of rapamycin (mTOR) signaling. In normal rat kidneys, sestrin 2 was selectively expressed in parietal epithelial cells (PECs), identified by the marker protein gene product 9.5. In adriamycin nephropathy, sestrin 2 expression decreased in PECs on day 14, together with increased expression of phosphorylated S6 ribosomal protein (P-S6RP), a downstream target of mTOR. Sestrin 2 expression was markedly decreased on day 42, coinciding with glomerulosclerosis and severe periglomerular fibrosis. In puromycin aminonucleoside nephropathy, decreased sestrin 2 expression, increased P-S6RP expression, and periglomerular fibrosis were observed on day 9, when massive proteinuria developed. These changes were transient and nearly normalized by day 28. In crescentic glomerulonephritis, sestrin 2 expression was not detected in cellular crescents, whereas P-S6RP increased. In conditionally immortalized cultured PECs, the forced downregulation of sestrin 2 by short hairpin RNA resulted in increased expression of P-S6RP and increased apoptosis. These data suggest that sestrin 2 is involved in PEC homeostasis by regulating the activity of mTOR. In addition, sestrin 2 could be a novel marker of PECs, and decreased expression of sestrin 2 might be a marker of PEC injury.
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Affiliation(s)
- Hiroko Hamatani
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Keiju Hiromura
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan;
| | - Toru Sakairi
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Satoshi Takahashi
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Mitsuharu Watanabe
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Akito Maeshima
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Takamoto Ohse
- Division of Nephrology and Endocrinology, University of Tokyo School of Medicine, Tokyo, Japan; and
| | - Jeffery W Pippin
- Division of Nephrology, University of Washington, Seattle, Washington
| | | | - Yoshihisa Nojima
- Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi, Japan
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Sarhan M, El Serougy H, Hussein AM, El-Dosoky M, Sobh MA, Fouad SA, Sobh M, Elhusseini F. Impact of bone-marrow-derived mesenchymal stem cells on adriamycin-induced chronic nephropathy. Can J Physiol Pharmacol 2014; 92:733-43. [PMID: 25093892 DOI: 10.1139/cjpp-2013-0503] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVES To study the effects of bone-marrow-derived mesenchymal stem cells (BM-MSCs) on adriamycin (ADR)-induced chronic nephropathy in rats. METHODS 60 male Sprague-Dawley rats were distributed among 3 groups (20 rats each): (i) the negative control group, which was normal rats that received saline (vehicle); (ii) the positive control (ADR) group, which was rats that received 2 intravenous injections of ADR into the penile vein at 14 day intervals without treatment, and (iii) the MSC group, which were rats treated as for the ADR group that were also given 2 intravenous injections of MSCs (5 days after each ADR injection). RESULTS ADR caused a significant reduction in animal body mass, survival rate, hemoglobin (Hb) content, serum albumin, and renal GSH, and significantly increased serum levels of triglycerides, cholesterol, urinary protein excretion and kidney injury molecule-1 (KIM-1), renal MDA, as well as caspase-3 expression and glomerular and tubulointerstitial damage compared with the negative control group. MSC treatment failed to improve animal survival rate, body mass, Hb level, proteinuria, or hypoalbuminemia; however, it mildly improved the serum BUN, hyperlipidemia, caspase-3 expression, urinary levels of KIM-1, renal oxidative stress markers, and glomerular and tubulointerstitial damage score. CONCLUSION administration of BM-MSCs during induction of ADR nephropathy provides partial protection, which could be due to improvements in the levels of of endogenous antioxidants, reduction of apoptosis, and maintenance of the integrity of the glomerular membrane.
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Affiliation(s)
- Mohamed Sarhan
- a Department of Medical Physiology, Faculty of Medicine, Mansoura University, Egypt
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25
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Shankland SJ, Smeets B, Pippin JW, Moeller MJ. The emergence of the glomerular parietal epithelial cell. Nat Rev Nephrol 2014; 10:158-73. [PMID: 24468766 DOI: 10.1038/nrneph.2014.1] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Glomerular diseases are the leading causes of chronic and end-stage kidney disease. In the 1980s and 1990s, attention was focused on the biology and role of glomerular endothelial and mesangial cells. For the past two decades, seminal discoveries have been made in podocyte biology in health and disease. More recently, the glomerular parietal epithelial cell (PEC)-the fourth resident glomerular cell type-has been under active study, leading to a better understanding and definition of how these cells behave normally, and their potential roles in glomerular disease. Accordingly, this Review will focus on our current knowledge of PECs, in both health and disease. We discuss model systems to study PECs, how PECs might contribute to glomerulosclerosis, crescent and pseudocrescent formation and how PECs handle filtered albumin. These events have consequences on PEC structure and function, and PECs have potential roles as stem or progenitor cells for podocytes in glomerular regeneration, which will also be described.
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Affiliation(s)
- Stuart J Shankland
- Division of Nephrology, University of Washington, 1959 North East Pacific Avenue, Box 356521, Room BB1269, Seattle, WA 98195-6521, USA
| | - Bart Smeets
- Nephrology and Clinical Immunology, University Hospital of the RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany
| | - Jeffrey W Pippin
- Division of Nephrology, University of Washington, 1959 North East Pacific Avenue, Box 356521, Room BB1269, Seattle, WA 98195-6521, USA
| | - Marcus J Moeller
- Nephrology and Clinical Immunology, University Hospital of the RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany
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26
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Erkan E. Proteinuria and progression of glomerular diseases. Pediatr Nephrol 2013; 28:1049-58. [PMID: 23124512 DOI: 10.1007/s00467-012-2335-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 09/21/2012] [Accepted: 09/24/2012] [Indexed: 01/21/2023]
Abstract
One of the major challenges of nephrology is to develop therapeutic strategies to halt the progression of kidney diseases. In clinical settings, nephrotic-range proteinuria correlates with the rate of progression, particularly in glomerular diseases. Hence, the degree of proteinuria has been utilized to monitor the response to treatment as well as to predict outcome. However, the pathophysiology of proteinuria-induced progression remains unknown. Albumin accounts for the majority of the protein in nephrotic urine and as a result of this clinical observation studies have focused on understanding the adverse effects of albumin overload in the kidney. Albumin is internalized by receptor-mediated endocytosis in proximal tubule cells via low density lipoprotein (LDL) type receptor, megalin. Albumin at high concentrations mimicking nephrotic milieu has resulted in the upregulation of pro-inflammatory/fibrogenic genes and apoptosis in proximal tubule cells in in vivo and in vitro models of albumin overload. These properties of albumin on proximal tubule cells may explain extensive tubulointerstitial fibrosis and tubular atrophy observed in end-stage kidney disease. In addition to tubular toxicity, podocytes respond to proteinuric states by cytoskeletal alterations and loss of the differentiation marker synaptopodin. Identifying the molecular network of proteins involved in albumin handling will enable us to manipulate the specific signaling pathways and prevent damage caused by proteinuria.
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Affiliation(s)
- Elif Erkan
- Division of Pediatric Nephrology, Children's Hospital of Pittsburgh, 530 45th Street 5th Floor, Office # 5129, Pittsburgh, PA 15201, USA.
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27
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Pippin JW, Sparks MA, Glenn ST, Buitrago S, Coffman TM, Duffield JS, Gross KW, Shankland SJ. Cells of renin lineage are progenitors of podocytes and parietal epithelial cells in experimental glomerular disease. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:542-57. [PMID: 23769837 DOI: 10.1016/j.ajpath.2013.04.024] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 04/03/2013] [Accepted: 04/09/2013] [Indexed: 12/22/2022]
Abstract
Glomerular injury leads to podocyte loss, a process directly underlying progressive glomerular scarring and decline of kidney function. The inherent repair process is limited by the inability of podocytes to regenerate. Cells of renin lineage residing alongside glomerular capillaries are reported to have progenitor capacity. We investigated whether cells of renin lineage can repopulate the glomerulus after podocyte injury and serve as glomerular epithelial cell progenitors. Kidney cells expressing renin were genetically fate-mapped in adult Ren1cCreER×Rs-tdTomato-R, Ren1cCre×Rs-ZsGreen-R, and Ren1dCre×Z/EG reporter mice. Podocyte depletion was induced in all three cell-specific reporter mice by cytotoxic anti-podocyte antibodies. After a decrease in podocyte number, a significant increase in the number of labeled cells of renin lineage was observed in glomeruli in a focal distribution along Bowman's capsule, within the glomerular tuft, or in both locations. A subset of cells lining Bowman's capsule activated expression of the glomerular parietal epithelial cell markers paired box protein PAX2 and claudin-1. A subset of labeled cells within the glomerular tuft expressed the podocyte markers Wilms tumor protein 1, nephrin, podocin, and synaptopodin. Neither renin mRNA nor renin protein was detected de novo in diseased glomeruli. These findings provide initial evidence that cells of renin lineage may enhance glomerular regeneration by serving as progenitors for glomerular epithelial cells in glomerular disease characterized by podocyte depletion.
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Affiliation(s)
- Jeffrey W Pippin
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Seattle, Washington 98195-6521, USA
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Zhang J, Pippin JW, Krofft RD, Naito S, Liu ZH, Shankland SJ. Podocyte repopulation by renal progenitor cells following glucocorticoids treatment in experimental FSGS. Am J Physiol Renal Physiol 2013; 304:F1375-89. [PMID: 23486009 DOI: 10.1152/ajprenal.00020.2013] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Prednisone is a mainstay of treatment for patients with focal segmental glomerulosclerosis (FSGS), a disease characterized by reduced podocyte number and glomerulosclerosis. Although the systemic immune-modulatory effects of prednisone are well-known, direct tissue effects on glomerular cells are poorly understood. Experimental FSGS was induced in mice with a cytotoxic anti-podocyte antibody, resulting in an abrupt decrease in podocyte number by day 3, proteinuria, and the development of glomerulosclerosis. Administering daily prednisone to mice with FSGS, beginning at day 3, significantly increased podocyte number at weeks 2 and 4. Podocyte number did not increase in control mice with FSGS given DMSO. The increase in podocyte number in prednisone-treated mice correlated significantly with reduced glomerulosclerosis. Prednisone reduced podocyte apoptosis measured by synaptopodin⁺/caspase-3⁺ double staining. Additionally, the number of podocyte progenitors, defined as cells expressing both a parietal epithelial cell protein and a podocyte protein, was significantly increased in prednisone-treated mice with FSGS at weeks 2 and 4. This was associated with increased phospho-ERK staining in both parietal epithelial cells (PAX2⁺/p-ERK⁺) and in podocyte progenitors (WT-1⁺/p-ERK⁺ lining Bowman's capsule). These data show that in this model of experimental FSGS, prednisone augments glomerular repair by increasing podocyte number through direct effects on both glomerular epithelial cells. Prednisone limits podocyte loss by reducing apoptosis, and it increases regeneration by augmenting the number of podocyte progenitors. The data support a direct glomerular cell action for prednisone in improving outcomes in FSGS.
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Affiliation(s)
- Jiong Zhang
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA
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Okamura K, Dummer P, Kopp J, Qiu L, Levi M, Faubel S, Blaine J. Endocytosis of albumin by podocytes elicits an inflammatory response and induces apoptotic cell death. PLoS One 2013; 8:e54817. [PMID: 23382978 PMCID: PMC3557279 DOI: 10.1371/journal.pone.0054817] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Accepted: 12/17/2012] [Indexed: 12/11/2022] Open
Abstract
The presence of albuminuria is strongly associated with progression of chronic kidney disease. While albuminuria has been shown to injure renal proximal tubular cells, the effects of albumin on podocytes have been less well studied. We have addressed the hypothesis that exposure of podocytes to albumin initiates an injury response. We studied transformed human-urine derived podocytes-like epithelial cells (HUPECS, or podocytes). Upon differentiation, these cells retain certain characteristics of differentiated podocytes, including expression of synaptopodin, CD2AP, and nestin. We exposed podocytes to recombinant human albumin, which lacks lipids and proteins that bind serum albumin; this reagent allowed a direct examination of the effects of albumin. Podocytes endocytosed fluoresceinated albumin and this process was inhibited at 4°C, suggesting an energy-dependent process. Exposure to albumin at concentrations of 5 and 10 mg/ml was associated with increased cell death in a dose-dependent manner. The mechanism of cell death may involve apoptosis, as caspase 3/7 were activated and the pan-caspase inhibitor z-VAD reduced cell death. Albumin exposure also increased nuclear factor (NF)-κB activation and increased transcription and release of interleukin (IL-) 1β, tumor necrosis factor (TNF), and IL-6. We extended these findings to an in vivo model. Glomeruli isolated from mice with nephrotic syndrome also had increased expression of IL-1β and TNF RNA. These data suggest that while podocyte injury begets albuminuria, albumin in the glomerular ultrafiltrate may also beget podocyte injury. Thus, an additional mechanism by which anti-proteinuric therapies are beneficial in the treatment of glomerular diseases may be a reduction in injury to the podocyte by albumin.
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Affiliation(s)
- Kayo Okamura
- Department of Medicine, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Patrick Dummer
- Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jeffrey Kopp
- Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Liru Qiu
- Department of Medicine, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Moshe Levi
- Department of Medicine, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Sarah Faubel
- Department of Medicine, University of Colorado Denver, Aurora, Colorado, United States of America
| | - Judith Blaine
- Department of Medicine, University of Colorado Denver, Aurora, Colorado, United States of America
- * E-mail:
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30
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Zhang J, Pippin JW, Vaughan MR, Krofft RD, Taniguchi Y, Romagnani P, Nelson PJ, Liu ZH, Shankland SJ. Retinoids augment the expression of podocyte proteins by glomerular parietal epithelial cells in experimental glomerular disease. Nephron Clin Pract 2012; 121:e23-37. [PMID: 23107969 DOI: 10.1159/000342808] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Accepted: 08/14/2012] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND/AIMS A decrease in glomerular podocyte number in membranous nephropathy and focal segmental glomerulosclerosis (FSGS) ultimately underlines glomerulosclerosis and the decrease in kidney function. Recent studies have shown that in these diseases, glomerular parietal epithelial cells begin to express proteins considered unique to podocytes, and that these glomerular epithelial transition cells might serve as podocyte progenitors. Because retinoids improve many forms of experimental glomerular disease characterized by podocyte injury and loss, we asked if all-trans retinoic acid (ATRA) induces parietal epithelial cells to express podocyte proteins. METHODS ATRA or vehicle was administered to rats with experimental membranous nephropathy (passive Heymann nephritis model) and mice with experimental FSGS (anti-glomerular antibody model) following the onset of proteinuria. Immunohistochemistry staining of PAX2 (parietal epithelial cell marker), WT-1 (podocyte cell marker), and Ki-67 (proliferation marker) were performed on kidney tissues. RESULTS Compared to diseased animals receiving vehicle, ATRA statistically significantly increased the number of glomerular transition cells, defined as cells double-staining for PAX2 and WT-1, in membranous nephropathy at weeks 2, 5 and 16, and in FSGS at weeks 1 and 2. This was accompanied by an increase in the number of podocytes compared to diseased controls receiving vehicle. CONCLUSION ATRA increases the number of glomerular epithelial transition cells in experimental proteinuric glomerular diseases. Thus, ATRA may provide a useful pharmacologic approach to decipher the mechanisms underlying the possible progenitor role of parietal epithelial cells.
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Affiliation(s)
- Jiong Zhang
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Seattle, Wash 98195-6521, USA
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