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Monte Neto JTD, Kirsztajn GM. The role of podocyte injury in the pathogenesis of Fabry disease nephropathy. J Bras Nefrol 2024; 46:e20240035. [PMID: 39058283 PMCID: PMC11287863 DOI: 10.1590/2175-8239-jbn-2024-0035en] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 05/02/2024] [Indexed: 07/28/2024] Open
Abstract
Renal involvement is one of the most severe morbidities of Fabry disease (FD), a multisystemic lysosomal storage disease with an X-linked inheritance pattern. It results from pathogenic variants in the GLA gene (Xq22.2), which encodes the production of alpha-galactosidase A (α-Gal), responsible for glycosphingolipid metabolism. Insufficient activity of this lysosomal enzyme generates deposits of unprocessed intermediate substrates, especially globotriaosylceramide (Gb3) and derivatives, triggering cellular injury and subsequently, multiple organ dysfunction, including chronic nephropathy. Kidney injury in FD is classically attributed to Gb3 deposits in renal cells, with podocytes being the main target of the pathological process, in which structural and functional alterations are established early and severely. This configures a typical hereditary metabolic podocytopathy, whose clinical manifestations are proteinuria and progressive renal failure. Although late clinical outcomes and morphological changes are well established in this nephropathy, the molecular mechanisms that trigger and accelerate podocyte injury have not yet been fully elucidated. Podocytes are highly specialized and differentiated cells that cover the outer surface of glomerular capillaries, playing a crucial role in preserving the structure and function of the glomerular filtration barrier. They are frequent targets of injury in many nephropathies. Furthermore, dysfunction and depletion of glomerular podocytes are essential events implicated in the pathogenesis of chronic kidney disease progression. We will review the biology of podocytes and their crucial role in regulating the glomerular filtration barrier, analyzing the main pathogenic pathways involved in podocyte injury, especially related to FD nephropathy.
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2
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Okabe M, Koike K, Yamamoto I, Tsuboi N, Matsusaka T, Yokoo T. Early growth response 1 as a podocyte injury marker in human glomerular diseases. Clin Kidney J 2024; 17:sfad289. [PMID: 38186896 PMCID: PMC10768762 DOI: 10.1093/ckj/sfad289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Indexed: 01/09/2024] Open
Abstract
Background In human glomerular diseases, visualizing podocyte injury is desirable since podocytes do not regenerate and podocyte injury leads to podocyte loss. Herein, we investigated the utility of immunostaining for early growth response 1 (EGR1), which is expressed in injured podocytes from the early stages of injury in animal experiments, as a podocyte injury marker in human glomerular diseases. Methods This study included 102 patients with biopsy-proven glomerular diseases between 2018 and 2021. The proportion of EGR1 expression in podocytes (%EGR1pod) was analyzed in relation to clinical and histopathological features, including glomerular and urinary podocyte-specific markers. Results %EGR1pod correlated significantly with the urinary protein:creatinine ratio, urinary nephrin and podocin mRNA levels, and glomerular podocin staining (rho = 0.361, 0.514, 0.487 and -0.417, respectively; adjusted P = .002, <.001, <.001 and <.001, respectively). Additionally, %EGR1pod correlated with cellular/fibrocellular crescents (rho = 0.479, adjusted P <.001). %EGR1pod was high in patients with glomerulonephritis, such as immunoglobulin A nephropathy (IgAN), lupus nephritis and antineutrophil cytoplasmic antibody-associated glomerulonephritis, and in those with podocytopathies, such as membranous nephropathy and primary focal segmental glomerulosclerosis, while %EGR1pod was low in patients with minimal change disease. In a subgroup analysis of IgAN, %EGR1pod was higher in Oxford C1 patients than in C0 patients. However, unexpectedly, patients with higher %EGR1pod were more prone to attain proteinuria remission, suggesting that EGR1 in the context of IgAN reflects reversible early injury. Conclusions Our findings indicate that EGR1 is a promising potential marker for identifying active early podocyte injury in human glomerular diseases.
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Affiliation(s)
- Masahiro Okabe
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan
| | - Kentaro Koike
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan
| | - Izumi Yamamoto
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan
| | - Nobuo Tsuboi
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan
| | - Taiji Matsusaka
- Departments of Basic Medicine, Tokai University School of Medicine, Isehara, Japan
| | - Takashi Yokoo
- Division of Nephrology and Hypertension, Department of Internal Medicine, Jikei University School of Medicine, Tokyo, Japan
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Ozkan S, Isildar B, Ercin M, Gezginci-Oktayoglu S, Konukoglu D, Neşetoğlu N, Oncul M, Koyuturk M. Therapeutic potential of conditioned medium obtained from deferoxamine preconditioned umbilical cord mesenchymal stem cells on diabetic nephropathy model. Stem Cell Res Ther 2022; 13:438. [PMID: 36056427 PMCID: PMC9438289 DOI: 10.1186/s13287-022-03121-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 08/04/2022] [Indexed: 11/10/2022] Open
Abstract
Background The therapeutic potential of mesenchymal stem cells (MSCs)-derived conditioned media (CM) can be increased after preconditioning with various chemical agents. The aim of this study is comparative evaluation of effects of N-CM and DFS-CM which are collected from normal (N) and deferoxamine (DFS) preconditioned umbilical cord-derived MSCs on rat diabetic nephropathy (DN) model. Methods After incubation of the MSCs in serum-free medium with/without 150 µM DFS for 48 h, the contents of N-CM and DFS-CM were analyzed by enzyme-linked immunosorbent assay. Diabetes (D) was induced by single dose of 55 mg/kg streptozotocin. Therapeutic effects of CMs were evaluated by biochemical, physical, histopathological and immunohistochemical analysis. Results The concentrations of vascular endothelial growth factor alpha, nerve growth factor and glial-derived neurotrophic factor in DFS-CM increased, while one of brain-derived neurotrophic factor decreased in comparison with N-CM. The creatinine clearance rate increased significantly in both treatment groups, while the improvement in albumin/creatinine ratio and renal mass index values were only significant for D + DFS-CM group. Light and electron microscopic deteriorations and loss of podocytes-specific nephrin and Wilms tumor-1 (WT-1) expressions were significantly restored in both treatment groups. Tubular beclin-1 expression was significantly increased for DN group, but it decreased in both treatment groups. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive apoptotic cell death increased in the tubules of D group, while it was only significantly decreased for D + DFS-CM group. Conclusions DFS-CM can be more effective in the treatment of DN by reducing podocyte damage and tubular apoptotic cell death and regulating autophagic activity with its more concentrated secretome content than N-CM. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13287-022-03121-6.
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Affiliation(s)
- Serbay Ozkan
- Histology and Embryology Department, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Kocamustafapaşa Street, 34098, Istanbul, Turkey
| | - Basak Isildar
- Histology and Embryology Department, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Kocamustafapaşa Street, 34098, Istanbul, Turkey
| | - Merve Ercin
- Biology Department, Molecular Biology Section, Faculty of Science, Istanbul University, Istanbul, Turkey
| | - Selda Gezginci-Oktayoglu
- Biology Department, Molecular Biology Section, Faculty of Science, Istanbul University, Istanbul, Turkey
| | - Dildar Konukoglu
- Medical Biochemistry Department, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Neşet Neşetoğlu
- Faculty of Pharmacy, Drug Application and Research Center, Istanbul University, Istanbul, Turkey
| | - Mahmut Oncul
- Cerrahpasa Faculty of Medicine, Obstetrics and Gynecology Department, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Meral Koyuturk
- Histology and Embryology Department, Cerrahpasa Faculty of Medicine, Istanbul University-Cerrahpasa, Kocamustafapaşa Street, 34098, Istanbul, Turkey.
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4
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Shankland SJ, Wang Y, Shaw AS, Vaughan JC, Pippin JW, Wessely O. Podocyte Aging: Why and How Getting Old Matters. J Am Soc Nephrol 2021; 32:2697-2713. [PMID: 34716239 PMCID: PMC8806106 DOI: 10.1681/asn.2021050614] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 08/26/2021] [Indexed: 02/04/2023] Open
Abstract
The effects of healthy aging on the kidney, and how these effects intersect with superimposed diseases, are highly relevant in the context of the population's increasing longevity. Age-associated changes to podocytes, which are terminally differentiated glomerular epithelial cells, adversely affect kidney health. This review discusses the molecular and cellular mechanisms underlying podocyte aging, how these mechanisms might be augmented by disease in the aged kidney, and approaches to mitigate progressive damage to podocytes. Furthermore, we address how biologic pathways such as those associated with cellular growth confound aging in humans and rodents.
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Affiliation(s)
- Stuart J. Shankland
- Division of Nephrology, University of Washington, Seattle, Washington
- Institute for Stem Cell & Regenerative Medicine, University of Washington, Seattle, Washington
| | - Yuliang Wang
- Institute for Stem Cell & Regenerative Medicine, University of Washington, Seattle, Washington
- Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, Washington
| | - Andrey S. Shaw
- Department of Research Biology, Genentech, South San Francisco, California
| | - Joshua C. Vaughan
- Department of Chemistry, University of Washington, Seattle, Washington
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington
| | - Jeffrey W. Pippin
- Division of Nephrology, University of Washington, Seattle, Washington
| | - Oliver Wessely
- Lerner Research Institute, Department of Cardiovascular & Metabolic Sciences, Cleveland Clinic Foundation, Cleveland, Ohio
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5
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Jiang M, Zhao M, Bai M, Lei J, Yuan Y, Huang S, Zhang Y, Ding G, Jia Z, Zhang A. SIRT1 Alleviates Aldosterone-Induced Podocyte Injury by Suppressing Mitochondrial Dysfunction and NLRP3 Inflammasome Activation. KIDNEY DISEASES (BASEL, SWITZERLAND) 2021; 7:293-305. [PMID: 34395544 DOI: 10.1159/000513884] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/08/2020] [Indexed: 01/02/2023]
Abstract
BACKGROUND Podocyte injury contributes to progressive glomerulosclerosis. Previously, we demonstrated the important role of the NLR family pyrin domain containing 3 (NLRP3) inflammasome in mediating the podocyte injury induced by aldosterone. Silent mating type information regulation 2 homolog 1 (SIRT1) is an NAD+-dependent deacetylase that is associated with the regulation of cellular inflammation. However, whether the activation of the NLRP3 inflammasome in podocytes is regulated by SIRT1, and the mechanism involved, remains unknown. METHODS In this study, we detected SIRT1 expression in patients with podocyte disease and performed an aldosterone infusion model in podocyte-specific Sirt1 knockout mice. In cultured podocytes, we used plasmids to overexpress SIRT1 and treated the podocyte with aldosterone. RESULTS SIRT1 was significantly decreased in the glomeruli of patients with podocyte disease. Sirt1-deficient mice showed significant urinary albumin excretion after aldosterone infusion, and the severity of the glomerular injury was significantly greater in podocyte-specific Sirt1 knockout mice than in the wild-type mice. Moreover, podocyte conditional Sirt1 knockout aggravated NLRP3 inflammasome activation and mitochondrial dysfunction (MtD). In vitro, overexpression of SIRT1 inhibited NLRP3 activation, protected against MtD and podocyte injury. CONCLUSION Taken together, these findings revealed a novel regulatory mechanism of the NLRP3 inflammasome by SIRT1 by promoting mitochondrial function, which provides some potential targets for the treatment of glomerular diseases.
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Affiliation(s)
- Mingzhu Jiang
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Min Zhao
- Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China.,Department of Nephrology, Nanjing Drum Tower Hospital, Nanjing, China
| | - Mi Bai
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Juan Lei
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Yanggang Yuan
- Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province Hospital, Nanjing, China
| | - Songming Huang
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Yue Zhang
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Guixia Ding
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Zhanjun Jia
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Aihua Zhang
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
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6
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Liu Y, Su YY, Yang Q, Zhou T. Stem cells in the treatment of renal fibrosis: a review of preclinical and clinical studies of renal fibrosis pathogenesis. Stem Cell Res Ther 2021; 12:333. [PMID: 34112221 PMCID: PMC8194041 DOI: 10.1186/s13287-021-02391-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 05/14/2021] [Indexed: 02/05/2023] Open
Abstract
Renal fibrosis commonly leads to glomerulosclerosis and renal interstitial fibrosis and the main pathological basis involves tubular atrophy and the abnormal increase and excessive deposition of extracellular matrix (ECM). Renal fibrosis can progress to chronic kidney disease. Stem cells have multilineage differentiation potential under appropriate conditions and are easy to obtain. At present, there have been some studies showing that stem cells can alleviate the accumulation of ECM and renal fibrosis. However, the sources of stem cells and the types of renal fibrosis or renal fibrosis models used in these studies have differed. In this review, we summarize the pathogenesis (including signaling pathways) of renal fibrosis, and the effect of stem cell therapy on renal fibrosis as described in preclinical and clinical studies. We found that stem cells from various sources have certain effects on improving renal function and alleviating renal fibrosis. However, additional clinical studies should be conducted to confirm this conclusion in the future.
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Affiliation(s)
- Yiping Liu
- Department of Nephrology, the Second Affiliated Hospital of Shantou University Medical College, No. 69 Dongsha Road, Shantou, 515041, China
| | - Yan-Yan Su
- Department of Nephrology, Huadu District People's Hospital of Guangzhou, Southern Medical University, Guangzhou, China
| | - Qian Yang
- Department of Nephrology, the Second Affiliated Hospital of Shantou University Medical College, No. 69 Dongsha Road, Shantou, 515041, China
| | - Tianbiao Zhou
- Department of Nephrology, the Second Affiliated Hospital of Shantou University Medical College, No. 69 Dongsha Road, Shantou, 515041, China.
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7
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Kravets I, Mallipattu SK. The Role of Podocytes and Podocyte-Associated Biomarkers in Diagnosis and Treatment of Diabetic Kidney Disease. J Endocr Soc 2020; 4:bvaa029. [PMID: 32232184 PMCID: PMC7093089 DOI: 10.1210/jendso/bvaa029] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 02/27/2020] [Indexed: 12/23/2022] Open
Abstract
Diabetic kidney disease (DKD) is an important public health problem. Podocyte injury is a central event in the mechanism of DKD development. Podocytes are terminally differentiated, highly specialized glomerular visceral epithelial cells critical for the maintenance of the glomerular filtration barrier. Although potential mechanisms by which diabetic milieu contributes to irreversible loss of podocytes have been described, identification of markers that prognosticate either the development of DKD or the progression to end-stage kidney disease (ESKD) have only recently made it to the forefront. Currently, the most common marker of early DKD is microalbuminuria; however, this marker has significant limitations: not all diabetic patients with microalbuminuria will progress to ESKD and as many as 30% of patients with DKD have normal urine albumin levels. Several novel biomarkers indicating glomerular or tubular damage precede microalbuminuria, suggesting that the latter develops when significant kidney injury has already occurred. Because podocyte injury plays a key role in DKD pathogenesis, identification of markers of early podocyte injury or loss may play an important role in the early diagnosis of DKD. Such biomarkers in the urine include podocyte-released microparticles as well as expression of podocyte-specific markers. Here, we review the mechanisms by which podocyte injury contributes to DKD as well as key markers that have been recently implicated in the development and/or progression of DKD and might serve to identify individuals that require earlier preventative care and treatment in order to slow the progression to ESKD.
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Affiliation(s)
- Igor Kravets
- Division of Endocrinology, Department of Medicine, Stony Brook University, Stony Brook, NY
| | - Sandeep K Mallipattu
- Division of Nephrology, Department of Medicine, Stony Brook University, Stony Brook, NY
- Renal Section, Northport VA Medical Center, Northport, NY
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8
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Lang Y, Zhao Y, Zheng C, Lu Y, Wu J, Zhu X, Zhang M, Yang F, Xu X, Shi S, Liu Z. MiR-30 family prevents uPAR-ITGB3 signaling activation through calcineurin-NFATC pathway to protect podocytes. Cell Death Dis 2019; 10:401. [PMID: 31127093 PMCID: PMC6534572 DOI: 10.1038/s41419-019-1625-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/12/2019] [Accepted: 04/15/2019] [Indexed: 11/09/2022]
Abstract
Urokinase plasminogen activator receptor (uPAR) is upregulated in podocytes of glomerular diseases and crucially mediates podocyte injury through integrin β3 (ITGB3). We previously showed that the miR-30 family maintains podocyte structure and function by inhibiting injurious calcineurin signaling through nuclear factor of activated T cells C (NFATC). Here, we tested whether the miR-30-calcineurin-NFATC and uPAR-ITGB3 pathways, two of the major pathways leading to podocyte injury, could interact. We found that podocyte-specific miR-30 knockdown in mice induced uPAR upregulation and ITGB3 activation, accompanied by proteinuria and podocyte injury. These effects of miR-30 knockdown were reduced using inhibitors of ITGB3, calcineurin, and NFATC, respectively, which are known to be antiproteinuric. These results indicate that miR-30 deficiency leads to calcineurin-NFATC signaling activation, which in turn activates the uPAR-ITGB3 pathway. In cultured podocytes, miR-30 knockdown also activated uPAR-ITGB3 signaling, leading to Rho GTPase activation, synaptopodin downregulation and podocyte injury. To explore uPAR-ITGB3 signaling regulation by miR-30 in podocytopathy development, we treated mice with lipopolysaccharide (LPS) and found that miR-30 was downregulated in podocytes, accompanied by uPAR upregulation and ITGB3 activation. We obtained the same results in cultured podocytes treated with LPS. Podocyte-specific transgenic miR-30 abolished uPAR-ITGB3 signaling and ameliorated podocyte injury and proteinuria in mice. Taken together, these experiments show that uPAR-ITGB3 signaling is negatively regulated by miR-30 through calcineurin-NFATC pathway, a novel mechanism underlying podocyte injury in glomerular diseases. Our study has elucidated the relationship among the crucial players governing podocyte pathophysiology and the antiproteinuric actions of drugs commonly used for podocytopathies.
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Affiliation(s)
- Yue Lang
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, 210002, China
| | - Yue Zhao
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, 210002, China
| | - Chunxia Zheng
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, 210002, China
| | - Yinghui Lu
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, 210002, China
| | - Junnan Wu
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, 210002, China
| | - Xiaodong Zhu
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, 210002, China
| | - Mingchao Zhang
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, 210002, China
| | - Fan Yang
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, 210002, China
| | - Xiaodong Xu
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, 210002, China
| | - Shaolin Shi
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, 210002, China.
| | - Zhihong Liu
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, 210002, China.
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Abstract
The main cellular constituents in glomerular mesangium are mesangial cells, which account for approximately 30-40% of the total cells in the glomerulus. Together with the mesangial matrix, mesangial cells form the glomerular basement membrane (GBM) in the glomerulus, whose main function is to perform the filtration. Under the pathologic conditions, mesangial cells are activated, leading to hyperproliferation and excess extracellular matrix (ECM). Moreover, mesangial cells also secrete several kinds of inflammatory cytokines, adhesion molecules, chemokines, and enzymes, all of which participate in the process of renal glomerular fibrosis. During the past years, researchers have revealed the roles of mesangial cells and the associated signal pathways involved in renal fibrosis. In this section, we will discuss how mesangial cells are activated and its contributions to renal fibrosis, as well as the molecular mechanisms and novel anti-fibrotic agents. Full understanding of the contributions of mesangial cells to renal fibrosis will benefit the clinical drug developing.
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Affiliation(s)
- Jing-Hong Zhao
- Department of Nephrology, Xinqiao Hospital, Army Medical University, Chongqing, China.
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10
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Cellular and molecular mechanisms of kidney fibrosis. Mol Aspects Med 2018; 65:16-36. [PMID: 29909119 DOI: 10.1016/j.mam.2018.06.002] [Citation(s) in RCA: 280] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 06/12/2018] [Indexed: 12/14/2022]
Abstract
Renal fibrosis is the final pathological process common to any ongoing, chronic kidney injury or maladaptive repair. It is considered as the underlying pathological process of chronic kidney disease (CKD), which affects more than 10% of world population and for which treatment options are limited. Renal fibrosis is defined by excessive deposition of extracellular matrix, which disrupts and replaces the functional parenchyma that leads to organ failure. Kidney's histological structure can be divided into three main compartments, all of which can be affected by fibrosis, specifically termed glomerulosclerosis in glomeruli, interstitial fibrosis in tubulointerstitium and arteriosclerosis and perivascular fibrosis in vasculature. In this review, we summarized the different appearance, cellular origin and major emerging processes and mediators of fibrosis in each compartment. We also depicted and discussed the challenges in translation of anti-fibrotic treatment to clinical practice and discuss possible solutions and future directions.
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ARF6 mediates nephrin tyrosine phosphorylation-induced podocyte cellular dynamics. PLoS One 2017; 12:e0184575. [PMID: 28880939 PMCID: PMC5589247 DOI: 10.1371/journal.pone.0184575] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 08/26/2017] [Indexed: 01/10/2023] Open
Abstract
ADP-ribosylation factor 6 (ARF6) is a small GTPase necessary for regulating cellular structure, motility, and vesicle trafficking. In several cellular systems, ARF6 was shown to regulate actin dynamics in coordination with Rac1, a Rho small GTPase. We examined the function of ARF6 in the kidney podocyte because Rac1 was implicated in kidney diseases involving this cell. We found that ARF6 expression was enriched in human podocytes and that it modulated podocyte cytoskeletal dynamics through a functional interaction with nephrin, an intercellular junction protein necessary for podocyte injury-induced signaling requiring activation by tyrosine phosphorylation of its cytoplasmic domain. ARF6 was necessary for nephrin activation-induced ruffling and focal adhesion turnover, possibly by altering Rac1 activity. In podocyte-specific Arf6 (ARF6_PodKO) knockout mice, ARF6 deficiency did not result in a spontaneous kidney developmental phenotype or proteinuria after aging. However, ARF6_PodKO mice exhibited distinct phenotypes in two in vivo glomerular injury models. In the protamine sulfate perfusion model, which induced acute podocyte effacement, ARF6_PodKO mice were protected from podocyte effacement. In the nephrotoxic serum nephritis model, which induced immune-complex mediated injury, ARF6_PodKO mice exhibited aggravated proteinuria. Together, these observations suggest that while ARF6 is necessary for nephrin tyrosine phosphorylation-induced cytoskeletal dynamics in cultured podocytes, ARF6 has pleotropic podocyte roles in vivo, where glomerular injury-specific mechanisms might activate distinct signaling pathways that dictate whether ARF6 activity is beneficial or deleterious for maintaining the integrity of the glomerular filtration barrier.
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12
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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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13
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Cai X, Bao L, Ren J, Li Y, Zhang Z. Grape seed procyanidin B2 protects podocytes from high glucose-induced mitochondrial dysfunction and apoptosis via the AMPK-SIRT1-PGC-1α axis in vitro. Food Funct 2016; 7:805-15. [PMID: 26650960 DOI: 10.1039/c5fo01062d] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Grape seed procyanidin B2 (GSPB2) was reported to have protective effects on diabetic nephropathy (DN) as a strong antioxidant. Our previous studies demonstrated that GSPB2 was effective in ameliorating podocyte injury in rats with DN. However, little is known about the benefits of GSPB2 in protecting against podocyte apoptosis and its molecular mechanisms in vitro. In the present study, we investigated whether GSPB2 could protect podocytes from high glucose-induced apoptosis and explored the possible mechanism. Cell viability and apoptosis were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry, respectively. The intracellular reactive oxygen species (ROS) level was measured using a dichlorofluorescein diacetate (DCFH-DA) fluorescent probe. Real-time reverse transcription-PCR was used to determine the gene expression of nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM), and quantitative real-time PCR was used to detect mitochondrial DNA (mtDNA) copy number. Western blots were carried out for the related protein expression in podocytes. Our results showed that GSPB2 significantly inhibited high glucose-induced podocyte apoptosis and increased the expression of nephrin and podocalyxin. GSPB2 treatment also suppressed intracellular ROS production and oxidative stress. The mRNA expressions of NRF-1, TFAM and mtDNA copy number were markedly increased, and mitochondrial swelling was effectively reduced in podocytes cultured under high glucose after GSPB2 treatment. The AMPK-SIRT1-PGC-1α axis was also activated by GSPB2 intervention. In conclusion, GSPB2 protected podocytes from high glucose-induced mitochondrial dysfunction and apoptosis via the AMPK-SIRT1-PGC-1α axis in vitro, suggesting a potential role of GSPB2 in the treatment of DN.
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Affiliation(s)
- Xiaxia Cai
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing, P. R. China.
| | - Lei Bao
- Department of Clinical Nutrition, Peking University International Hospital, Beijing, P. R. China
| | - Jinwei Ren
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing, P. R. China.
| | - Yong Li
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing, P. R. China.
| | - Zhaofeng Zhang
- Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing, P. R. China.
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14
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Obesity-related glomerulopathy: clinical and pathologic characteristics and pathogenesis. Nat Rev Nephrol 2016; 12:453-71. [PMID: 27263398 DOI: 10.1038/nrneph.2016.75] [Citation(s) in RCA: 425] [Impact Index Per Article: 53.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The prevalence of obesity-related glomerulopathy is increasing in parallel with the worldwide obesity epidemic. Glomerular hypertrophy and adaptive focal segmental glomerulosclerosis define the condition pathologically. The glomerulus enlarges in response to obesity-induced increases in glomerular filtration rate, renal plasma flow, filtration fraction and tubular sodium reabsorption. Normal insulin/phosphatidylinositol 3-kinase/Akt and mTOR signalling are critical for podocyte hypertrophy and adaptation. Adipokines and ectopic lipid accumulation in the kidney promote insulin resistance of podocytes and maladaptive responses to cope with the mechanical forces of renal hyperfiltration. Although most patients have stable or slowly progressive proteinuria, up to one-third develop progressive renal failure and end-stage renal disease. Renin-angiotensin-aldosterone blockade is effective in the short-term but weight loss by hypocaloric diet or bariatric surgery has induced more consistent and dramatic antiproteinuric effects and reversal of hyperfiltration. Altered fatty acid and cholesterol metabolism are increasingly recognized as key mediators of renal lipid accumulation, inflammation, oxidative stress and fibrosis. Newer therapies directed to lipid metabolism, including SREBP antagonists, PPARα agonists, FXR and TGR5 agonists, and LXR agonists, hold therapeutic promise.
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15
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Zhuang A, Forbes JM. Diabetic kidney disease: a role for advanced glycation end-product receptor 1 (AGE-R1)? Glycoconj J 2016; 33:645-52. [PMID: 27270766 DOI: 10.1007/s10719-016-9693-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 05/26/2016] [Accepted: 05/27/2016] [Indexed: 01/07/2023]
Abstract
Diabetic patients are postulated to be in a perpetual state of oxidative stress and inflammation at sites where chronic complications occur. The accumulation of AGEs derived from both endogenous and exogenous sources (such as the diet) have been implicated in the development and progression of diabetic complications, particularly nephropathy. There has been some interest in investigating the potential for reducing the AGE burden in chronic disease, through the action of AGE "clearance" receptors, such as the advanced glycation end-product receptor 1 (AGE-R1). Reducing the burden of AGEs has been linked to attenuation of inflammation, slower progression of diabetic complications (in particular vascular and renal complications) and has been shown to extend lifespan. To date, however, there have been no direct investigations into whether AGE-R1 has any role in modulating normal kidney function, or specifically during the development and progression of diabetes. This mini-review will focus on the recent advances in knowledge around the mechanistic function of AGE-R1 and the implications of this for the pathogenesis of diabetic kidney disease.
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Affiliation(s)
- Aowen Zhuang
- Glycation and Diabetes Group, Mater Research Institute, Translational Research Institute, The University of Queensland, South Brisbane, Queensland, Australia
| | - Josephine M Forbes
- Glycation and Diabetes Group, Mater Research Institute, Translational Research Institute, The University of Queensland, South Brisbane, Queensland, Australia. .,Mater Clinical School, The University of Queensland, South Brisbane, Queensland, Australia.
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16
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Lemley KV. Glomerular pathology and the progression of chronic kidney disease. Am J Physiol Renal Physiol 2016; 310:F1385-8. [DOI: 10.1152/ajprenal.00099.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 04/20/2016] [Indexed: 11/22/2022] Open
Abstract
Structural studies of the glomerulus, largely undertaken in animal models, have informed our understanding of the progression of chronic kidney disease (CKD) for decades. A fundamental tenet of that understanding is that a loss of podocytes underlies progression in many or most cases of progressive CKD. Recent attempts have been made to reconcile earlier findings from glomerular physiology (the primacy of glomerular capillary hypertension in causation of secondary glomerular sclerosis) with structural findings and have suggested a more detailed model of the mechanisms underlying podocyte detachment as viable cells. A new appreciation of the main locus of mechanical challenges to the podocyte (in the filtration slit) may both explain the renoprotective action of some current therapies and help to suggest novel therapeutic strategies.
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Affiliation(s)
- Kevin V. Lemley
- Department of Pediatrics, University of Southern California Keck School of Medicine, Los Angeles, California; and
- Division of Nephrology, Children's Hospital Los Angeles, Los Angeles, California
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17
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Kikuchi M, Wickman L, Hodgin JB, Wiggins RC. Podometrics as a Potential Clinical Tool for Glomerular Disease Management. Semin Nephrol 2016. [PMID: 26215862 DOI: 10.1016/j.semnephrol.2015.04.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Chronic kidney disease culminating in end-stage kidney disease is a major public health problem costing in excess of $40 billion per year with high morbidity and mortality. Current tools for glomerular disease monitoring lack precision and contribute to poor outcome. The podocyte depletion hypothesis describes the major mechanisms underlying the progression of glomerular diseases, which are responsible for more than 80% of cases of end-stage kidney disease. The question arises of whether this new knowledge can be used to improve outcomes and reduce costs. Podocytes have unique characteristics that make them an attractive monitoring tool. Methodologies for estimating podocyte number, size, density, glomerular volume and other parameters in routine kidney biopsies, and the rate of podocyte detachment from glomeruli into urine (podometrics) now have been developed and validated. They potentially fill important gaps in the glomerular disease monitoring toolbox. The application of these tools to glomerular disease groups shows good correlation with outcome, although data validating their use for individual decision making is not yet available. Given the urgency of the clinical problem, we argue that the time has come to focus on testing these tools for application to individualized clinical decision making toward more effective progression prevention.
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Affiliation(s)
- Masao Kikuchi
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | - Larysa Wickman
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI
| | | | - Roger C Wiggins
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI.
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18
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Abstract
Diabetes is increasing in prevalence and is the leading cause of end-stage renal disease in the United States. Diabetic kidney disease is considered a proteinuric glomerular disease. Although the glomerulus is composed of various cell types, research suggests that podocytes are critical to overall glomerular health. Podocyte injury has been identified as a pivotal event resulting in proteinuric kidney disease, glomerulosclerosis, and loss of renal function. Thus, understanding the signaling mechanisms that trigger podocyte injury in diabetic kidney disease might allow for the development of targeted therapeutics to prevent or ameliorate progression to end-stage renal failure. This review focuses on the role of podocytes in diabetic kidney disease.
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Affiliation(s)
- Jamie S Lin
- Renal-Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Katalin Susztak
- Renal-Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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19
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Zhou YS, Ihmoda IA, Phelps RG, Bellamy CO, Turner AN. Following specific podocyte injury captopril protects against progressive long term renal damage. F1000Res 2015; 4:172. [PMID: 26629332 PMCID: PMC4642846 DOI: 10.12688/f1000research.4030.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/05/2015] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Angiotensin converting enzyme inhibitors (ACEi) reduce proteinuria and preserve kidney function in proteinuric renal diseases. Their nephroprotective effect exceeds that attributable to lowering of blood pressure alone. This study examines the potential of ACEi to protect from progression of injury after a highly specific injury to podocytes in a mouse model. METHODS We created transgenic (Podo-DTR) mice in which graded specific podocyte injury could be induced by a single injection of diphtheria toxin. Transgenic and wild-type mice were given the ACEi captopril in drinking water, or water alone, commencing 24h after toxin injection. Kidneys were examined histologically at 8 weeks and injury assessed by observers blinded to experimental group. RESULTS After toxin injection, Podo-DTR mice developed acute proteinuria, and at higher doses transient renal impairment, which subsided within 3 weeks to be followed by a slow glomerular scarring process. Captopril treatment in Podo-DTR line 57 after toxin injection at 5ng/g body weight reduced proteinuria and ameliorated glomerular scarring, matrix accumulation and glomerulosclerosis almost to baseline (toxin: 17%; toxin + ACEi 10%, p<0.04; control 7% glomerular scarring). Podocyte counts were reduced after toxin treatment and showed no recovery irrespective of captopril treatment (7.1 and 7.3 podocytes per glomerular cross section in water and captopril-treated animals compared with 8.2 of wild-type controls, p<0.05). CONCLUSIONS Observations in Podo-DTR mice support the hypothesis that continuing podocyte dysfunction is a key abnormality in proteinuric disease. Our model is ideal for studying strategies to protect the kidney from progressive injury following podocyte depletion. Demonstrable protective effects from captopril occur, despite indiscernible preservation or restoration of podocyte counts, at least after this degree of relatively mild injury.
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Affiliation(s)
- Yu S Zhou
- Centre for Inflammation Research, Renal Medicine, University of Edinburgh and Royal Infirmary, Edinburgh, EH16 4SB, UK
| | - Ihmoda A Ihmoda
- Centre for Inflammation Research, Renal Medicine, University of Edinburgh and Royal Infirmary, Edinburgh, EH16 4SB, UK
| | - Richard G Phelps
- Centre for Inflammation Research, Renal Medicine, University of Edinburgh and Royal Infirmary, Edinburgh, EH16 4SB, UK
| | - Christopher Os Bellamy
- Centre for Inflammation Research, Renal Medicine, University of Edinburgh and Royal Infirmary, Edinburgh, EH16 4SB, UK
| | - A Neil Turner
- Centre for Inflammation Research, Renal Medicine, University of Edinburgh and Royal Infirmary, Edinburgh, EH16 4SB, UK
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20
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Kwiatkowski S, Kwiatkowska E, Rzepka R, Kurkiewicz V, Mikołajek-Bedner W, Torbè A. Development of a focal segmental glomerulosclerosis after pregnancy complicated by preeclampsia: case report and review of literature. J Matern Fetal Neonatal Med 2015; 29:1566-9. [DOI: 10.3109/14767058.2015.1053865] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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21
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LIU XIANGCHUN, ZHANG HONG, WANG QUN, YU KEZHOU, WANG RONG, SUN JING. Blockade of vascular endothelial growth factor-A/receptor 2 exhibits a protective effect on angiotensin-II stimulated podocytes. Mol Med Rep 2015; 12:4340-4345. [DOI: 10.3892/mmr.2015.3911] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 04/10/2015] [Indexed: 11/06/2022] Open
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22
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Hodgin JB, Bitzer M, Wickman L, Afshinnia F, Wang SQ, O'Connor C, Yang Y, Meadowbrooke C, Chowdhury M, Kikuchi M, Wiggins JE, Wiggins RC. Glomerular Aging and Focal Global Glomerulosclerosis: A Podometric Perspective. J Am Soc Nephrol 2015; 26:3162-78. [PMID: 26038526 DOI: 10.1681/asn.2014080752] [Citation(s) in RCA: 164] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 02/08/2015] [Indexed: 11/03/2022] Open
Abstract
Kidney aging is associated with an increasing proportion of globally scarred glomeruli, decreasing renal function, and exponentially increasing ESRD prevalence. In model systems, podocyte depletion causes glomerulosclerosis, suggesting age-associated glomerulosclerosis could be caused by a similar mechanism. We measured podocyte number, size, density, and glomerular volume in 89 normal kidney samples from living and deceased kidney donors and normal poles of nephrectomies. Podocyte nuclear density decreased with age due to a combination of decreased podocyte number per glomerulus and increased glomerular volume. Compensatory podocyte cell hypertrophy prevented a change in the proportion of tuft volume occupied by podocytes. Young kidneys had high podocyte reserve (podocyte density >300 per 10(6) µm(3)), but by 70-80 years of age, average podocyte nuclear density decreased to, <100 per 10(6) µm(3), with corresponding podocyte hypertrophy. In older age podocyte detachment rate (urine podocin mRNA-to-creatinine ratio) was higher than at younger ages and podocytes were stressed (increased urine podocin-to-nephrin mRNA ratio). Moreover, in older kidneys, proteinaceous material accumulated in the Bowman space of glomeruli with low podocyte density. In a subset of these glomeruli, mass podocyte detachment events occurred in association with podocytes becoming binucleate (mitotic podocyte catastrophe) and subsequent wrinkling of glomerular capillaries, tuft collapse, and periglomerular fibrosis. In kidneys of young patients with underlying glomerular diseases similar pathologic events were identified in association with focal global glomerulosclerosis. Podocyte density reduction with age may therefore directly lead to focal global glomerulosclerosis, and all progressive glomerular diseases can be considered superimposed accelerators of this underlying process.
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Affiliation(s)
| | | | - Larysa Wickman
- Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan
| | | | | | | | | | - Chrysta Meadowbrooke
- Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan
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23
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Hua W, Huang HZ, Tan LT, Wan JM, Gui HB, Zhao L, Ruan XZ, Chen XM, Du XG. CD36 Mediated Fatty Acid-Induced Podocyte Apoptosis via Oxidative Stress. PLoS One 2015; 10:e0127507. [PMID: 26000608 PMCID: PMC4441449 DOI: 10.1371/journal.pone.0127507] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 04/13/2015] [Indexed: 12/14/2022] Open
Abstract
Background Hyperlipidemia-induced apoptosis mediated by fatty acid translocase CD36 is associated with increased uptake of ox-LDL or fatty acid in macrophages, hepatocytes and proximal tubular epithelial cells, leading to atherosclerosis, liver damage and fibrosis in obese patients, and diabetic nephropathy (DN), respectively. However, the specific role of CD36 in podocyte apoptosis in DN with hyperlipidemia remains poorly investigated. Methods The expression of CD36 was measured in paraffin-embedded kidney tissue samples (Ctr = 18, DN = 20) by immunohistochemistry and immunofluorescence staining. We cultured conditionally immortalized mouse podocytes (MPC5) and treated cells with palmitic acid, and measured CD36 expression by real-time PCR, Western blot analysis and immunofluorescence; lipid uptake by Oil red O staining and BODIPY staining; apoptosis by flow cytometry assay, TUNEL assay and Western blot analysis; and ROS production by DCFH-DA fluorescence staining. All statistical analyses were performed using SPSS 21.0 statistical software. Results CD36 expression was increased in kidney tissue from DN patients with hyperlipidemia. Palmitic acid upregulated CD36 expression and promoted its translocation from cytoplasm to plasma membrane in podocytes. Furthermore, palmitic acid increased lipid uptake, ROS production and apoptosis in podocytes, Sulfo-N-succinimidyloleate (SSO), the specific inhibitor of the fatty acid binding site on CD36, decreased palmitic acid-induced fatty acid accumulation, ROS production, and apoptosis in podocytes. Antioxidant 4-hydroxy-2,2,6,6- tetramethylpiperidine -1-oxyl (tempol) inhibited the overproduction of ROS and apoptosis in podocytes induced by palmitic acid. Conclusions CD36 mediated fatty acid-induced podocyte apoptosis via oxidative stress might participate in the process of DN.
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Affiliation(s)
- Wei Hua
- Department of Nephrology, The First Affiliated Hospital of Chongqing Medical University, Youyi Road 1, Chongqing, 400042, China
| | - Hui-zhe Huang
- Faculty of Basic Medical Sciences, Chongqing Medical University, Medical College Road 1, Chongqing, 400016, China
| | - Lan-ting Tan
- Emergency Department, The First Affiliated Hospital of Chongqing Medical University, Youyi Road 1, Chongqing, 400042, China
| | - Jiang-min Wan
- Department of Nephrology, The First Affiliated Hospital of Chongqing Medical University, Youyi Road 1, Chongqing, 400042, China
| | - Hai-bo Gui
- Emergency Department, The First Affiliated Hospital of Chongqing Medical University, Youyi Road 1, Chongqing, 400042, China
| | - Liang Zhao
- Faculty of Basic Medical Sciences, Chongqing Medical University, Medical College Road 1, Chongqing, 400016, China
| | - Xiong-zhong Ruan
- Centre for Nephrology, Royal Free and University College Medical School, University College London, Royal Free Campus, Rowland Hill Street, London, NW3 2PF, United Kingdom
- Centre for Lipid Research, Key Laboratory of Molecular Biology on Infectious Diseases, Ministry of Education, Chongqing Medical University, Youyi Road 1, Chongqing, 400042, China
| | - Xue-mei Chen
- Emergency Department, The First Affiliated Hospital of Chongqing Medical University, Youyi Road 1, Chongqing, 400042, China
- * E-mail: (XMC); (XGD)
| | - Xiao-gang Du
- Department of Nephrology, The First Affiliated Hospital of Chongqing Medical University, Youyi Road 1, Chongqing, 400042, China
- Laboratory of Lipid & Glucose Metabolism, The First Affiliated Hospital of Chongqing Medical University, Youyi Road 1, Chongqing, 400042, China
- * E-mail: (XMC); (XGD)
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Lionaki S, Vlachopanos G, Georgalis A, Liapis G, Skalioti C, Zavos G, Boletis JN. Individualized scheme of immunoadsorption for the recurrence of idiopathic focal segmental glomerulosclerosis in the graft: a single center experience. Ren Fail 2015; 37:777-83. [PMID: 25715638 DOI: 10.3109/0886022x.2015.1015366] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
OBJECTIVES To explore the role of immunoadsorption (IA) for the treatment of idiopathic focal segmental glomerulosclerosis (FSGS) recurrence in the renal allograft, if applied in a personalized manner. METHODS We studied patients with end-stage renal disease (ESRD) due to idiopathic FSGS, transplanted between 2001 and 2010. Patients with FSGS recurrence were treated with daily sessions of IA for the first week, followed by an every other day scheme and then individualized tapering until discontinuation. Complete remission was defined as a reduction of 24-h proteinuria to ≤ 0.5 g/day and partial remission as a reduction of 24-h proteinuria to 50% or more from baseline. RESULTS Of the 18 renal transplant recipients with ESRD due to idiopathic FSGS, 12 (66.7%) experienced disease recurrence in a mean time of 0.75 months post-transplantation (KTx), with a mean proteinuria of 8.9 g/day at the time of recurrence. The mean recipient age was 30.8 years; the mean donor age was 47.4 years, while living related donors provided the allograft in seven cases. Four of the patients received therapy with rituximab in addition to IA. During a mean time of follow-up of 48.3 months, seven patients (58.3%) achieved complete remission, and five (41.7%) partial remission. At the end of follow-up, eight patients (66.7%) had functioning grafts, being in sustained remission, in contrast to four patients (33.3%), who ended up in ESRD because of FSGS recurrence. CONCLUSIONS IA was shown efficacious in a small series of patients with recurrent FSGS in the graft. Renal function remained stable in eight of the 12 patients with FSGS recurrence.
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Affiliation(s)
- Sophia Lionaki
- a Department of Nephrology & Transplantation Unit , Laiko Hospital , Athens , Greece
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25
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Venkatachalam MA. Could Autophagic Exhaustion Be a Final Common Pathway for Podocytopathy in FSGS? J Am Soc Nephrol 2014; 26:999-1001. [PMID: 25406340 DOI: 10.1681/asn.2014090919] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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26
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Wu X, An P, Ye B, Shi X, Dang H, Fu R, Qiao C. Artemisinin ameliorated proteinuria in rats with adriamycin-induced nephropathy through regulating nephrin and podocin expressions. J TRADIT CHIN MED 2014; 34:63-8. [DOI: 10.1016/s0254-6272(14)60056-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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27
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Kriz W, Hähnel B, Hosser H, Rösener S, Waldherr R. Structural analysis of how podocytes detach from the glomerular basement membrane under hypertrophic stress. Front Endocrinol (Lausanne) 2014; 5:207. [PMID: 25566184 PMCID: PMC4264519 DOI: 10.3389/fendo.2014.00207] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 11/17/2014] [Indexed: 01/09/2023] Open
Abstract
Podocytes are lost by detachment from the GBM as viable cells; details are largely unknown. We studied this process in the rat after growth stimulation with FGF-2. Endothelial and mesangial cells responded by hyperplasia, podocytes underwent hypertrophy, but, in the long run, developed various changes that could either be interpreted showing progressing stages in detachment from the GBM or stages leading to a tighter attachment by foot process effacement (FPE). This occurred in microdomains within the same podocyte; thus, features of detachment and of reinforced attachment may simultaneously be found in the same podocyte. (1) Initially, hypertrophied podocytes underwent cell body attenuation and formed large pseudocysts, i.e., expansions of the subpodocyte space. (2) Podocytes entered the process of FPE starting with the retraction of foot processes (FPs) and the replacement of the slit diaphragm by occluding junctions, thereby sealing the filtration slits. Successful completion of this process led to broad attachments of podocyte cell bodies to the GBM. (3) Failure of sealing the slits led to gaps of varying width between retracting FPs facilitating the outflow of the filtrate from the GBM. (4) Since those gaps are frequently overarched by broadened primary processes, the drainage of the filtrate into the Bowman's space may be hindered leading to the formation of small pseudocysts associated with bare areas of GBM. (5) The merging of pseudocysts created a system of communicating chambers through which the filtrate has to pass to reach Bowman's space. Multiple flow resistances in series likely generated an expansile force on podocytes contributing to detachment. (6) Such a situation appears to proceed to complete disconnection generally of a group of podocytes owing to the junctional connections between them. (7) Since such groups of detaching podocytes generally make contact to parietal cells, they start the formation of tuft adhesions to Bowman's capsule.
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Affiliation(s)
- Wilhelm Kriz
- Institute of Transfusion Medicine and Immunology, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- Institute of Neuroanatomy, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- *Correspondence: Wilhelm Kriz, Zentrum für Biomedizin und Medizintechnik Mannheim, Institut für Neuroanatomie, Ludolf-Krehl-Str. 13-17, Tridomus C, Ebene 6, Mannheim D68167, Germany e-mail:
| | - Brunhilde Hähnel
- Institute of Neuroanatomy, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Hiltraud Hosser
- Institute of Neuroanatomy, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
- Pathologie Heidelberg, Heidelberg, Germany
| | - Sigrid Rösener
- Global Non-Clinical Safety, Merck KGaA, Merck Serono, Darmstadt, Germany
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Cheng C, Zheng Z, Shi C, Liu X, Ye Z, Lou T. Advanced glycation end-products reduce podocyte adhesion by activating the renin-angiotensin system and increasing integrin-linked kinase. Exp Ther Med 2013; 6:1494-1498. [PMID: 24255680 PMCID: PMC3829755 DOI: 10.3892/etm.2013.1312] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 09/18/2013] [Indexed: 11/29/2022] Open
Abstract
The aim of this study was to investigate the effects of advanced glycation end-products (AGEs) on podocyte adhesion and the underlying mechanisms. Immortalized mouse podocytes were exposed to various conditions and podocyte adhesion was evaluated using a hexosaminidase assay. The expression levels of integrin-linked kinase (ILK) were measured by quantitative polymerase chain reaction (qPCR) and western blotting. Treatment with AGEs resulted in a significant, concentration-dependent reduction in podocyte adhesion (P<0.05) and an incremental rise in ILK expression up to a maximum of 100%. Pretreatment with losartan significantly prevented the upregulation of ILK and attenuated the loss of podocyte adhesion observed in podocytes exposed to AGEs (P<0.05). However, the adhesion of losartan-treated podocytes remained lower than that of the podocytes exposed to bovine serum albumin. The results indicate that AGEs reduce podocyte adhesion via the upregulation of ILK expression, which occurs partly through activation of the renin-angiotensin system in podocytes.
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Affiliation(s)
- Cailian Cheng
- Department of Nephrology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510630, P.R. China
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29
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Wickman L, Afshinnia F, Wang SQ, Yang Y, Wang F, Chowdhury M, Graham D, Hawkins J, Nishizono R, Tanzer M, Wiggins J, Escobar GA, Rovin B, Song P, Gipson D, Kershaw D, Wiggins RC. Urine podocyte mRNAs, proteinuria, and progression in human glomerular diseases. J Am Soc Nephrol 2013; 24:2081-95. [PMID: 24052633 DOI: 10.1681/asn.2013020173] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Model systems demonstrate that progression to ESRD is driven by progressive podocyte depletion (the podocyte depletion hypothesis) and can be noninvasively monitored through measurement of urine pellet podocyte mRNAs. To test these concepts in humans, we analyzed urine pellet mRNAs from 358 adult and pediatric kidney clinic patients and 291 controls (n=1143 samples). Compared with controls, urine podocyte mRNAs increased 79-fold (P<0.001) in patients with biopsy-proven glomerular disease and a 50% decrease in kidney function or progression to ESRD. An independent cohort of patients with Alport syndrome had a 23-fold increase in urinary podocyte mRNAs (P<0.001 compared with controls). Urinary podocyte mRNAs increased during active disease but returned to baseline on disease remission. Furthermore, urine podocyte mRNAs increased in all categories of glomerular disease evaluated, but levels ranged from high to normal, consistent with individual patient variability in the risk for progression. In contrast, urine podocyte mRNAs did not increase in polycystic kidney disease. The association between proteinuria and podocyturia varied markedly by glomerular disease type: a high correlation in minimal-change disease and a low correlation in membranous nephropathy. These data support the podocyte depletion hypothesis as the mechanism driving progression in all human glomerular diseases, suggest that urine pellet podocyte mRNAs could be useful for monitoring risk for progression and response to treatment, and provide novel insights into glomerular disease pathophysiology.
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Abstract
Wnt/Ctnnb1 and Notch signaling play key roles in kidney development and epithelial cell specification. Recent reports have suggested that these pathways are reactivated in response to injury and in different disease conditions. Studies using genetically modified animal models showed that sustained activation of Notch and Wnt signaling in podocytes are causally related to albuminuria and glomerulosclerosis development. Here, we discuss the role and regulation of Wnt/Ctnnb1 and Notch signaling in podocytes.
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Affiliation(s)
- Hideki Kato
- Department of Medicine, Division of Nephrology, University of Teikyo, Tokyo, Japan
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Cravedi P, Kopp JB, Remuzzi G. Recent progress in the pathophysiology and treatment of FSGS recurrence. Am J Transplant 2013; 13:266-74. [PMID: 23312002 PMCID: PMC3558619 DOI: 10.1111/ajt.12045] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 11/05/2012] [Accepted: 11/06/2012] [Indexed: 01/25/2023]
Abstract
Focal segmental glomerulosclerosis (FSGS) is a glomerular disease characterized by proteinuria, frequent progression to end-stage renal disease, and recurrence after kidney transplantation in ∼25% of patients, which negatively impacts long-term allograft survival. Experimental studies suggest that abnormalities in T and, possibly, B cells may represent one initial pathogenic trigger, leading to podocyte injury and progressive loss. New data also support the existence of circulating permeability factors able to damage the podocytes, but no single molecule has been consistently identified as the causal pathogenic element in FSGS recurrence. Unfortunately, major progress from mechanistic studies has not translated into substantial advancements in patient treatment, with plasmapheresis (PP) and high doses of cyclosporine (CsA) remaining the mainstays of therapy. Despite consistent experimental and clinical evidence that treatment of proteinuria slows renal function decline in proteinuric nephropathies, maximal use of antiproteinuric agents such as renin angiotensin system antagonists is not routine in the management of FSGS recurrence. More recently, encouraging results have been reported with anti-CD20 depleting antibody rituximab, but further studies are needed to establish its safety/efficacy profile.
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Affiliation(s)
- Paolo Cravedi
- Mario Negri Institute for Pharmacological Research, Clinical Research Center for Rare Diseases “Aldo e Cele Dacco”, Villa Camozzi, Ranica, Bergamo, Italy
| | - Jeffrey B. Kopp
- Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Giuseppe Remuzzi
- Mario Negri Institute for Pharmacological Research, Clinical Research Center for Rare Diseases “Aldo e Cele Dacco”, Villa Camozzi, Ranica, Bergamo, Italy,Unit of Nephrology, Azienda Ospedaliera Ospedali Riuniti di Bergamo, Bergamo, Italy
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Abstract
PURPOSE OF REVIEW Focal segmental glomerulosclerosis (FSGS) is a major cause of nephrotic syndrome and renal failure. All forms of FSGS share podocyte injury and depletion as central mediators. This review focuses on new insights into pathogenesis from study of extrinsic toxins in experimental models, permeability factors in human disease, and novel genetic causes. RECENT FINDINGS Experimental toxin models have advanced our understanding of the threshold and dynamics of podocyte injury. Following initial podocyte depletion, spreading fields of podocyte injury through secondary mediators appear to be important in generating the segmental pathologic lesions. Proliferating glomerular epithelial cells are common in FSGS, although there are conflicting views about their identity. Evidence suggests potential contributions by mature parietal epithelial cells, facultative stem cells and podocytes. A number of novel candidate permeability factors that affect podocyte function and motility have been discovered in human FSGS and related podocytopathy minimal change disease. Exome capture has identified new monogenic causes of familial FSGS. Apolipoprotein L-1 (APOL1) is expressed in podocytes, and the prevalence of APOL1 risk alleles in patients of African descent with primary FSGS and HIV-associated nephropathy is high, implicating potential podocyte effects. SUMMARY FSGS is caused by a complex interplay of inherent genetic susceptibilities and external injurious factors acting on podocytes. Critical levels of podocyte stress eventuate in podocyte depletion, segmental glomerular scarring, and glomerular epithelial cell hyperplasia.
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Eddy AA, López-Guisa JM, Okamura DM, Yamaguchi I. Investigating mechanisms of chronic kidney disease in mouse models. Pediatr Nephrol 2012; 27:1233-47. [PMID: 21695449 PMCID: PMC3199379 DOI: 10.1007/s00467-011-1938-2] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 04/22/2011] [Accepted: 04/25/2011] [Indexed: 12/21/2022]
Abstract
Animal models of chronic kidney disease (CKD) are important experimental tools that are used to investigate novel mechanistic pathways and to validate potential new therapeutic interventions prior to pre-clinical testing in humans. Over the past several years, mouse CKD models have been extensively used for these purposes. Despite significant limitations, the model of unilateral ureteral obstruction (UUO) has essentially become the high-throughput in vivo model, as it recapitulates the fundamental pathogenetic mechanisms that typify all forms of CKD in a relatively short time span. In addition, several alternative mouse models are available that can be used to validate new mechanistic paradigms and/or novel therapies. Here, we review several models-both genetic and experimentally induced-that provide investigators with an opportunity to include renal functional study end-points together with quantitative measures of fibrosis severity, something that is not possible with the UUO model.
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Affiliation(s)
- Allison A Eddy
- Center for Tissue and Cell Sciences, Seattle Children's Research Institute, 1900 Ninth Avenue, M/S C9S-5, Seattle, WA 98101-1309, USA.
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Weber ML, Vang D, Velho PE, Gupta P, Crosson JT, Hebbel RP, Gupta K. Morphine promotes renal pathology in sickle mice. Int J Nephrol Renovasc Dis 2012; 5:109-18. [PMID: 22888269 PMCID: PMC3413037 DOI: 10.2147/ijnrd.s33813] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Patients with sickle cell disease (SCD) are often treated with opioids for severe pain. Although opioids are known to have renal-specific effects, their role in nephropathy in SCD remains unknown. Because a subset of patients receives opioids for long periods of time, we examined the influence of chronic morphine treatment on mice with pre-existing renal disease expressing varying amounts of sickle hemoglobin. Morphine treatment for 3–6 weeks resulted in a variety of defects in renal morphology observed using light and electron microscopy. Notably, morphine induced glomerular pathology, resulting in increased glomerular volume, mesangial expansion, mesangial cell proliferation, parietal cell metaplasia, podocyte effacement, and microvillus transformation. Cystic tubulopathy and hemeoxygenase-1 expression and activity were also increased in morphine-treated mice. Naloxone, a non-selective opioid receptor (OR) antagonist, ameliorated these effects. Functionally, the urine albumin to creatinine ratio was increased following acute as well as chronic morphine treatment. These results suggest that clinically relevant doses of morphine induce renal pathology and that OR antagonists may be effective for ameliorating morphine-induced renal disease.
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Affiliation(s)
- Marc L Weber
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Minnesota Medical School, Minneapolis, MN, USA
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Yang W, Wang J, Shi L, Yu L, Qian Y, Liu Y, Wang W, Cheng S. Podocyte injury and overexpression of vascular endothelial growth factor and transforming growth factor-beta 1 in adriamycin-induced nephropathy in rats. Cytokine 2012; 59:370-6. [PMID: 22579701 DOI: 10.1016/j.cyto.2012.04.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 03/19/2012] [Accepted: 04/11/2012] [Indexed: 11/25/2022]
Abstract
The aim of this study is to investigate the expression of nephrin, vascular endothelial growth factor (VEGF), transforming growth factor-beta 1 (TGF-β1), and podocyte number in adriamycin (ADR)-induced nephropathy. A total of 60 male Sprague-Dawley rats were randomly divided into the control group and the ADR nephropathy group. The nephropathy was induced by tail-vein injection of ADR (4 mg/kg) twice at a 14-day interval. The expression levels of nephrin, VEGF, and TGF-β1 in glomeruli were assessed by immunohistochemistry and western blotting. The podocyte number was also evaluated after anti-Wilms' tumor-1 (WT1) immunohistochemical staining. In addition, the urinary protein content, biochemical parameters in serum samples and glomerular sclerosis index (SI) were compared between groups. In the ADR nephropathy group, the expression levels of nephrin was significantly decreased with the fusion of podocyte foot processes at 6 weeks after the first ADR injection, which was associated with a marked proteinuria. A decrease in podocyte number and an increase in SI with the overexpression of both VEGF and TGF-β1 were also observed in the glomeruli at 10 weeks after the first ADR injection. This was associated with focal segmental glomerulosclerosis (FSGS). The study data suggest that podocyte injury and decreased nephrin, as well as increased VEGF and TGF-β1, may contribute to the development of proteinuria and FSGS in ADR-induced nephropathy in rats.
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Affiliation(s)
- Weina Yang
- Department of Anatomy, Histology & Embryology, Medicine School of Xi'an Jiaotong University, Xi'an, PR China
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Zheng M, Lv LL, Cao YH, Zhang JD, Wu M, Ma KL, Phillips AO, Liu BC. Urinary mRNA markers of epithelial-mesenchymal transition correlate with progression of diabetic nephropathy. Clin Endocrinol (Oxf) 2012; 76:657-64. [PMID: 21824169 DOI: 10.1111/j.1365-2265.2011.04192.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
OBJECTIVE Epithelial-mesenchymal transition (EMT) plays an important role in the pathogenesis and progression of diabetic nephropathy (DN). Quantification of messenger RNA (mRNA) expression in urinary sediment is emerging as a noninvasive method of screening DN-associated biomarkers. The aim of our study was to examine whether urinary mRNA profile of EMT-associated genes may provide valuable clinical insight into the different stages of DN. DESIGN AND METHODS Diabetic nephropathy patients (n = 44) and healthy controls (n = 12) were enrolled in this study. DN patients were divided into three groups according to the levels of estimated glomerular filtration rate (eGFR): Group A (eGFR > 60 ml/min per 1·73 m(2), n = 27), Group B (45 < eGFR < 60 ml/min per 1·73 m(2), n = 9), and Group C (eGFR < 45 ml/min per 1·73 m(2), n = 8). Relative mRNA abundance of α-smooth muscle actin (α-SMA), fibronectin, FSP1 and matrix metalloproteinase-9 (MMP-9) were quantified, and correlations between target mRNAs and clinical parameters were examined. RESULTS The urinary mRNA levels of α-SMA, fibronectin and MMP-9 were significantly higher in the DN group compared with controls (P < 0·05), and mRNA levels increased with DN progression. Urinary mRNA levels of all target genes positively correlated with both urinary albumin excretion (UAE) and blood urea nitrogen (BUN). Moreover, the expression of α-SMA, fibronectin and MMP-9 mRNA correlated with serum creatinine levels (r = 0·514, r = 0·53 and r = 0·469, all P < 0·001) and GFR levels (r = -0·374, r = -0·392 and r = -0·487, all P < 0·01). CONCLUSIONS Quantification of EMT-associated genes in urinary sediment may be a novel approach for searching new biomarkers of DN.
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Affiliation(s)
- Min Zheng
- Institute of Nephrology, Zhong Da Hospital, Southeast University School of Medicine, Nanjing, China
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Abstract
Progression of many glomerular diseases has been firmly tied to a loss of podocytes, followed by a deterioration of glomerular architectural stability eventuating in segmental, and ultimately global, sclerosis. Recent studies have begun to clarify the nature of the autonomous (disease-independent) aspects of this process, as well as to explore mechanistically the 'unreasonable effectiveness' of angiotensin blockade in slowing glomerular disease progression. Quantitative monitoring of podocyte loss (e.g., to assess therapy) remains a challenge.
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Affiliation(s)
- Kevin V Lemley
- Division of Nephrology, Children's Hospital Los Angeles, Los Angeles, California 90027, USA.
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Takagi N, Tanizawa T, Kon V, Fogo AB, Ichikawa I, Ma J. Mineralocorticoid Receptor Blocker Protects against Podocyte-Dependent Glomerulosclerosis. NEPHRON EXTRA 2012; 2:17-26. [PMID: 22479265 PMCID: PMC3318935 DOI: 10.1159/000334961] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Background We previously showed that angiotensin type 1 receptor (AT1) blocker (ARB) attenuates glomerular injury in Nphs1-hCD25 (NEP25) transgenic mice, a model of selective podocyte injury. However, subsequent studies in NEP25 mice with podocyte-specific deficiency of AT1 revealed that the protective effects of ARB are not through the podocyte AT1, thereby raising the possibility that the protective effects of ARB involve mineralocorticoids. Methods NEP25 mice were treated with the mineralocorticoid receptor blocker (MRB) spironolactone (25 mg/kg/day, n = 10), the ARB losartan (250 mg/kg/day, n = 11), both (ARB+MRB, n = 8) or vehicle (Vehicle, n = 9) from day −7 to day 9 of induction of podocyte injury. Results Although MRB did not reduce systolic blood pressure or proteinuria, addition of MRB to ARB significantly attenuated glomerulosclerosis (glomerulosclerosis index: ARB+MRB 1.67 ± 0.19 vs. MRB 2.01 ± 0.29, ARB 2.35 ± 0.19, and Vehicle 2.25 ± 0.26, p < 0.05) and preserved the number of WT1-positive podocytes (ARB+MRB 152.5 ± 9.7 vs. MRB 117.2 ± 9.0 or ARB 113.6 ± 7.4, and ARB+MRB vs. Vehicle 97.5 ± 4.0 per glomerulus; p < 0.05). Conclusion These data suggest that, while MRB does not attenuate proteinuria caused by podocyte-specific injury, it provides protective effects against glomerulosclerosis that is independent of systemic blood pressure.
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Affiliation(s)
- Nobuaki Takagi
- Division of Nephrology, Department of Pediatrics, Vanderbilt University, Nashville, Tenn., USA
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Sicking EM, Fuss A, Uhlig S, Jirak P, Dijkman H, Wetzels J, Engel DR, Urzynicok T, Heidenreich S, Kriz W, Kurts C, Ostendorf T, Floege J, Smeets B, Moeller MJ. Subtotal ablation of parietal epithelial cells induces crescent formation. J Am Soc Nephrol 2012; 23:629-40. [PMID: 22282596 DOI: 10.1681/asn.2011050449] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Parietal epithelial cells (PECs) of the renal glomerulus contribute to the formation of both cellular crescents in rapidly progressive GN and sclerotic lesions in FSGS. Subtotal transgenic ablation of podocytes induces FSGS but the effect of specific ablation of PECs is unknown. Here, we established an inducible transgenic mouse to allow subtotal ablation of PECs. Proteinuria developed during doxycycline-induced cellular ablation but fully reversed 26 days after termination of doxycycline administration. The ablation of PECs was focal, with only 30% of glomeruli exhibiting histologic changes; however, the number of PECs was reduced up to 90% within affected glomeruli. Ultrastructural analysis revealed disruption of PEC plasma membranes with cytoplasm shedding into Bowman's space. Podocytes showed focal foot process effacement, which was the most likely cause for transient proteinuria. After >9 days of cellular ablation, the remaining PECs formed cellular extensions to cover the denuded Bowman's capsule and expressed the activation marker CD44 de novo. The induced proliferation of PECs persisted throughout the observation period, resulting in the formation of typical cellular crescents with periglomerular infiltrate, albeit without accompanying proteinuria. In summary, subtotal ablation of PECs leads the remaining PECs to react with cellular activation and proliferation, which ultimately forms cellular crescents.
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Affiliation(s)
- Eva-Maria Sicking
- Division of Nephrology and Clinical Immunology, Medical Faculty, RWTH Aachen University, Aachen, Germany
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Angiotensin II-dependent persistent podocyte loss from destabilized glomeruli causes progression of end stage kidney disease. Kidney Int 2011; 81:40-55. [PMID: 21937979 DOI: 10.1038/ki.2011.306] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Podocyte depletion is a major mechanism driving glomerulosclerosis. Progression is the process by which progressive glomerulosclerosis leads to end stage kidney disease (ESKD). In order to determine mechanisms contributing to persistent podocyte loss, we used a human diphtheria toxin transgenic rat model. After initial diphtheria toxin-induced podocyte injury (over 30% loss in 4 weeks), glomeruli became destabilized, resulting in continued autonomous podocyte loss causing global podocyte depletion (ESKD) by 13 weeks. This was monitored by urine mRNA analysis and by quantitating podocytes in glomeruli. Similar patterns of podocyte depletion were found in the puromycin aminonucleoside and 5/6 nephrectomy rat models of progressive end-stage disease. Angiotensin II blockade (combined enalapril and losartan) restabilized the glomeruli, and prevented continuous podocyte loss and progression to ESKD. Discontinuing angiotensin II blockade resulted in recurrent glomerular destabilization, podocyte loss, and progression to ESKD. Reduction in blood pressure alone did not reduce proteinuria or prevent podocyte loss from destabilized glomeruli. The protective effect of angiotensin II blockade was entirely accounted for by reduced podocyte loss. Thus, an initiating event resulting in a critical degree of podocyte depletion can destabilize glomeruli and initiate a superimposed angiotensin II-dependent podocyte loss process that accelerates progression resulting in eventual global podocyte depletion and ESKD. These events can be monitored noninvasively in real-time through urine mRNA assays.
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Ma J, Matsusaka T, Yang HC, Zhong J, Takagi N, Fogo AB, Kon V, Ichikawa I. Induction of podocyte-derived VEGF ameliorates podocyte injury and subsequent abnormal glomerular development caused by puromycin aminonucleoside. Pediatr Res 2011; 70:83-9. [PMID: 21451433 PMCID: PMC3113658 DOI: 10.1203/pdr.0b013e31821bdf1c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Our previous studies using puromycin aminonucleoside (PAN) established that podocyte damage leads to glomerular growth arrest during development and glomerulosclerosis later in life. This study examined the potential benefit of maintaining podocyte-derived VEGF in podocyte defense and survival after PAN injury using conditional transgenic podocytes and mice, in which human VEGF-A (hVEGF) transgene expression is controlled by tetracycline responsive element (TRE) promoter and reverse tetracycline transactivator (rtTA) in podocytes. In vitro experiments used primary cultured podocytes harvested from mice carrying podocin-rtTA and TRE-hVEGF transgenes, in which hVEGF can be induced selectively. Induction of VEGF in PAN-exposed podocytes resulted in preservation of intrinsic VEGF, α-actinin-4 and synaptopodin, antiapoptotic marker Bcl-xL/Bax, as well as attenuation in apoptotic marker cleaved/total caspase-3. In vivo, compared with genotype controls, PAN-sensitive neonatal mice with physiologically relevant levels of podocyte-derived VEGF showed significantly larger glomeruli. Furthermore, PAN-induced up-regulation of desmin, down-regulation of synaptopodin and nephrin, and disruption of glomerular morphology were significantly attenuated in VEGF-induced transgenic mice. Our data indicate that podocyte-derived VEGF provides self-preservation functions, which can rescue the cell after injury and preempt subsequent deterioration of the glomerulus in developing mice.
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Affiliation(s)
- Ji Ma
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
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Matsusaka T, Sandgren E, Shintani A, Kon V, Pastan I, Fogo AB, Ichikawa I. Podocyte injury damages other podocytes. J Am Soc Nephrol 2011; 22:1275-85. [PMID: 21719786 DOI: 10.1681/asn.2010090963] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Loss of podocytes promotes glomerulosclerosis, but whether this results from a continued primary insult or a secondary mechanism triggered by the initial loss of podocytes is unknown. We generated chimeric mice in which only a subpopulation of podocytes expressed hCD25, which is the receptor for the immunotoxin LMB2. In addition, genetic labeling of hCD25-negative cells with human placental alkaline phosphatase allowed the study of these two distinct podocyte populations. Administration of LMB2 did not cause podocyte injury in hCD25-negative control mice. In contrast, LMB2 severely damaged or sloughed off the subpopulation of hCD25-positive podocytes within the chimeric glomeruli. Moreover, hCD25-negative podocytes, which were immune to the initial toxin injury, developed injury as early as 4 d after LMB2 injection, evidenced by foot process effacement, upregulation of desmin, and downregulation of nephrin, podocin, and podocalyxin. Furthermore, the magnitude of secondary injury correlated with the magnitude of primary injury, supporting the concept of an amplified cascade of podocyte injury. In conclusion, podocyte damage can propagate injury by triggering secondary damage of "remnant" intact podocytes, even when the primary insult is short-lived. This transmission of podocyte injury may form a vicious cycle leading to accelerated podocyte deterioration and glomerulosclerosis.
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Affiliation(s)
- Taiji Matsusaka
- Department of Internal Medicine, Tokai University School of Medicine, Isehara, Kanagawa, Japan
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44
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Urinary podocyte-associated mRNA profile in various stages of diabetic nephropathy. PLoS One 2011; 6:e20431. [PMID: 21655212 PMCID: PMC3105067 DOI: 10.1371/journal.pone.0020431] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 04/20/2011] [Indexed: 11/19/2022] Open
Abstract
Background Podocyte injury and subsequent excretion in urine play a crucial role in the pathogenesis and progression of diabetic nephropathy (DN). Quantification of messenger RNA (mRNA) expression in urinary sediment by real-time PCR is emerging as a noninvasive method of screening DN-associated biomarkers. We hypothesized that the urinary mRNA profile of podocyte-associated molecules may provide important clinical insight into the different stages of diabetic nephropathy. Methods DN patients (N = 51) and healthy controls (N = 13) were enrolled in this study. DN patients were divided into a normoalbuminuria group (UAE<30 mg/g, n = 17), a microalbuminuria group (UAE 30∼300 mg/g, n = 15), and a macroalbuminuria group (UAE>300 mg/g, n = 19), according to their urinary albumin excretion (UAE). Relative mRNA abundance of synaptopodin, podocalyxin, CD2-AP, α-actin4, and podocin were quantified, and correlations between target mRNAs and clinical parameters were examined. Results The urinary mRNA levels of all genes studied were significantly higher in the DN group compared with controls (p<0.05), and mRNA levels increased with DN progression. Urinary mRNA levels of all target genes positively correlated with both UAE and BUN. The expression of podocalyxin, CD2-AP, α-actin4, and podocin mRNA correlated with serum creatinine (r = 0.457, p = 0.001; r = 0.329, p = 0.01; r = 0.286, p = 0.021; r = 0.357, p = 0.006, respectively). Furthermore, podocalyxin mRNA was found to negatively correlate with eGFR (r = −0.349, p = 0.01). Conclusion The urinary mRNA profiles of synaptopodin, podocalyxin, CD2-AP, α-actin4, and podocin were found to increase with the progression of DN, which suggested that quantification of podocyte-associated molecules will be useful biomarkers of DN.
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Cheng H, Harris RC. The glomerulus--a view from the outside--the podocyte. Int J Biochem Cell Biol 2010; 42:1380-7. [PMID: 20542138 DOI: 10.1016/j.biocel.2010.05.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 04/12/2010] [Accepted: 05/30/2010] [Indexed: 01/11/2023]
Abstract
In the past decade, podocyte research has been greatly aided by the development of powerful new molecular, cellular and animal tools, leading to elucidation of an increasing number of proteins involved in podocyte function and identification of mutated genes in hereditary glomerulopathies. Accumulating evidence indicates that podocyte disorders may not only underlie these hereditary glomerulopathies but also play crucial role in a broad spectrum of acquired glomerular diseases. Genetic susceptibility, environmental influence and systemic responses are all involved in the mediation of the pathogenesis of podocytopathies. Injured podocytes may predisopose to further injury of other podocytes and other adjacent/distant renal cells in a vicious cycle, leading to inexorable progression of glomerular injury. The classic view is that podocytes have a limited ability to proliferate in the normal mature kidney. However, recent research in rodents has provided suggestive evidence for podocyte regeneration resulting from differentiation of progenitor cells within Bowman's capsule.
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Affiliation(s)
- Huifang Cheng
- Division of Nephrology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-2372, USA.
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46
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Abstract
Chronic kidney diseases result from recurrent or progressive injuries in glomeruli, tubules, interstitium and/or vasculature. In order to study pathogenesis, mechanisms and effects of interventions, many animal models have been developed, including spontaneous, genetic and induced models. However, these models do not exactly simulate human diseases, and most of them are strain, gender or age dependent. We review key information on various rodent models of chronic kidney diseases.
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Motojima M, Matsusaka T, Kon V, Ichikawa I. Fibrinogen that appears in Bowman's space of proteinuric kidneys in vivo activates podocyte Toll-like receptors 2 and 4 in vitro. Nephron Clin Pract 2009; 114:e39-47. [PMID: 19887845 DOI: 10.1159/000254390] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Accepted: 02/05/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Composition of nonselective proteinuria includes several endogenous ligands of Toll-like receptors (TLRs) not normally present in Bowman's space, thus raising the possibility that TLRs are involved in proteinuria-mediated podocyte injury. METHODS Kidneys of NEP25 mice, a model of glomerular sclerosis induced by podocyte-specific injury, were immunohistochemically evaluated for the presence of fibrin/fibrinogen, which are potent ligands for TLRs. A podocyte cell line was treated with fibrinogen or lipopolysaccharides and examined for expression of cytokines. siRNAs were used to knockdown components of TLR signaling. RESULTS We found deposits of fibrin/fibrinogen only in the damaged podocytes of proteinuric kidneys, indicating that podocytes are exposed to these potent TLR ligands in proteinuric state. In cultured podocytes, we confirmed mRNA expressions of TLR2, TLR4, as well as their major TLR signal transducer, MyD88. Fibrinogen and lipopolysaccharides dose-dependently upregulated mRNA expressions of MCP-1, TNF-alpha and TLR2 in podocytes as well as increased the MCP-1 protein in the medium. Knockdown of TLR2 and TLR4 inhibited the fibrinogen-induced MCP-1 mRNA upregulation. Knockdown of MyD88 also inhibited the upregulation. CONCLUSION These results suggest that plasma macromolecules that appear in Bowman's space in proteinuric conditions have the capacity to induce podocyte cytokines through TLRs, and thereby accelerate podocyte injury.
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Affiliation(s)
- Masaru Motojima
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
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48
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Lewko B, Stepinski J. Hyperglycemia and mechanical stress: Targeting the renal podocyte. J Cell Physiol 2009; 221:288-95. [DOI: 10.1002/jcp.21856] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Mollet G, Ratelade J, Boyer O, Muda AO, Morisset L, Lavin TA, Kitzis D, Dallman MJ, Bugeon L, Hubner N, Gubler MC, Antignac C, Esquivel EL. Podocin inactivation in mature kidneys causes focal segmental glomerulosclerosis and nephrotic syndrome. J Am Soc Nephrol 2009; 20:2181-9. [PMID: 19713307 DOI: 10.1681/asn.2009040379] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Podocin is a critical component of the glomerular slit diaphragm, and genetic mutations lead to both familial and sporadic forms of steroid-resistant nephrotic syndrome. In mice, constitutive absence of podocin leads to rapidly progressive renal disease characterized by mesangiolysis and/or mesangial sclerosis and nephrotic syndrome. Using established Cre-loxP technology, we inactivated podocin in the adult mouse kidney in a podocyte-specific manner. Progressive loss of podocin in the glomerulus recapitulated albuminuria, hypercholesterolemia, hypertension, and renal failure seen in nephrotic syndrome in humans. Lesions of FSGS appeared after 4 wk, with subsequent development of diffuse glomerulosclerosis and tubulointerstitial damage. Interestingly, conditional inactivation of podocin at birth resulted in a gradient of glomerular lesions, including mesangial proliferation, demonstrating a developmental stage dependence of renal histologic patterns of injury. The development of significant albuminuria in this model occurred only after early and focal foot process effacement had progressed to diffuse involvement, with complete absence of podocin immunolabeling at the slit diaphragm. Finally, we identified novel potential mediators and perturbed molecular pathways, including cellular proliferation, in the course of progression of renal disease leading to glomerulosclerosis, using global gene expression profiling.
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Cheng H, Fan X, Guan Y, Moeckel GW, Zent R, Harris RC. Distinct roles for basal and induced COX-2 in podocyte injury. J Am Soc Nephrol 2009; 20:1953-62. [PMID: 19643929 DOI: 10.1681/asn.2009010039] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Transgenic mice that overexpress cyclooxygenase-2 (COX-2) selectively in podocytes are more susceptible to glomerular injury by adriamycin and puromycin (PAN). To investigate the potential roles of COX-2 metabolites, we studied mice with selective deletion of prostanoid receptors and generated conditionally immortalized podocyte lines from mice with either COX-2 deletion or overexpression. Podocytes that overexpressed COX-2 were virtually indistinguishable from wild-type podocytes but were significantly more sensitive to PAN-induced injury, produced more prostaglandin E(2) and thromboxane B(2), and had greater expression of prostaglandin E(2) receptor subtype 4 (EP(4)) and thromboxane receptor (TP). Treatment of COX-2-overexpressing podocytes with a TP antagonist reduced apoptosis, but treatment with an EP(4) antagonist did not. In contrast, podocytes from COX-2-knockout mice exhibited increased apoptosis, markedly decreased cell adhesion, and prominent stress fibers. In vivo, selective deletion of podocyte EP(4) did not alter the increased sensitivity to adriamycin-induced injury observed in mice overexpressing podocyte COX-2. In contrast, genetic deletion of TP in these mice prevented adriamycin-induced injury, with attenuated albuminuria and foot process effacement. These results suggest that basal COX-2 may be important for podocyte survival, but overexpression of podocyte COX-2 increases susceptibility to podocyte injury, which is mediated, in part, by activation of the thromboxane receptor.
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Affiliation(s)
- Huifang Cheng
- Division of Nephrology, Vanderbilt University School of Medicine and Nashville Veterans Affairs Hospital, Nashville, TN 37232, USA
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