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Grubczak K, Starosz A, Makowska B, Parfienowicz Z, Krętowska M, Naumnik B, Moniuszko M. The influence of calcitriol and methylprednisolone on podocytes function in minimal change disease in vitro model. Sci Rep 2023; 13:12731. [PMID: 37543700 PMCID: PMC10404287 DOI: 10.1038/s41598-023-39893-x] [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: 04/13/2023] [Accepted: 08/01/2023] [Indexed: 08/07/2023] Open
Abstract
Minimal change disease (MCD), considered one of the major causes of nephrotic syndrome, is a complex pathological condition with disturbances in podocytes' foot processes. Numerous studies suggested the essential role of vitamin D3 in maintaining proper glomerulus function. However, the data on direct potential of that compound in reference to podocytes are scarce. Thus, here we assessed the influence of calcitriol (active vitamin D3) on podocyte function, apart from commonly used steroids (methylprednisolone). CIHP-1 podocyte cell line was used to implement the LPS-PAN-induced MCD in vitro model. Viability, podocyte-related slit diaphragm proteins, morphology, function as a barrier was evaluated using flow cytometry, RT-PCR, confocal microscopy, and TEER analysis. Calcitriol or methylprednisolone did not affect cell viability. Podocyte-related proteins demonstrated different responses to in vitro treatment compared to previously reported changes in total glomeruli. Podocyte morphology was partially restored in the presence of the tested compounds. In addition, TEER analysis revealed improvement of LPS-PAN-induced cells' function as a barrier when vitamin D3 or steroid was used. In conclusion, a significant potential for modulation of MCD in vitro model podocytes with calcitriol or selected steroids was reported. Further studies on vitamin D3 in context of podocyte-related phenomenon accompanying MCD are of great importance.
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Affiliation(s)
- Kamil Grubczak
- Department of Regenerative Medicine and Immune Regulation, Medical University of Białystok, Jerzego Waszyngtona 13, 15-269, Białystok, Poland.
| | - Aleksandra Starosz
- Department of Regenerative Medicine and Immune Regulation, Medical University of Białystok, Jerzego Waszyngtona 13, 15-269, Białystok, Poland
| | - Barbara Makowska
- Department of Regenerative Medicine and Immune Regulation, Medical University of Białystok, Jerzego Waszyngtona 13, 15-269, Białystok, Poland
| | - Zuzanna Parfienowicz
- Department of Regenerative Medicine and Immune Regulation, Medical University of Białystok, Jerzego Waszyngtona 13, 15-269, Białystok, Poland
| | - Magdalena Krętowska
- Department of Regenerative Medicine and Immune Regulation, Medical University of Białystok, Jerzego Waszyngtona 13, 15-269, Białystok, Poland
| | - Beata Naumnik
- Ist Department of Nephrology and Transplantation with Dialysis Unit, Medical University of Bialystok, Żurawia 14, 15-540, Białystok, Poland.
| | - Marcin Moniuszko
- Department of Regenerative Medicine and Immune Regulation, Medical University of Białystok, Jerzego Waszyngtona 13, 15-269, Białystok, Poland
- Department of Allergology and Internal Medicine, Medical University of Białystok, Marii Skłodowskiej-Curie 24A, 15-276, Białystok, Poland
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Blaine J, Dylewski J. Regulation of the Actin Cytoskeleton in Podocytes. Cells 2020; 9:cells9071700. [PMID: 32708597 PMCID: PMC7408282 DOI: 10.3390/cells9071700] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 06/30/2020] [Accepted: 07/07/2020] [Indexed: 12/13/2022] Open
Abstract
Podocytes are an integral part of the glomerular filtration barrier, a structure that prevents filtration of large proteins and macromolecules into the urine. Podocyte function is dependent on actin cytoskeleton regulation within the foot processes, structures that link podocytes to the glomerular basement membrane. Actin cytoskeleton dynamics in podocyte foot processes are complex and regulated by multiple proteins and other factors. There are two key signal integration and structural hubs within foot processes that regulate the actin cytoskeleton: the slit diaphragm and focal adhesions. Both modulate actin filament extension as well as foot process mobility. No matter what the initial cause, the final common pathway of podocyte damage is dysregulation of the actin cytoskeleton leading to foot process retraction and proteinuria. Disruption of the actin cytoskeleton can be due to acquired causes or to genetic mutations in key actin regulatory and signaling proteins. Here, we describe the major structural and signaling components that regulate the actin cytoskeleton in podocytes as well as acquired and genetic causes of actin dysregulation.
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Affiliation(s)
- Judith Blaine
- Renal Division, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA;
| | - James Dylewski
- Renal Division, University of Colorado Anschutz Medical Campus and Denver Health Medical Center, Aurora, CO 80045, USA
- Correspondence: ; Tel.: +303-724-4841
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Doykov ID, Heywood WE, Nikolaenko V, Śpiewak J, Hällqvist J, Clayton PT, Mills P, Warnock DG, Nowak A, Mills K. Rapid, proteomic urine assay for monitoring progressive organ disease in Fabry disease. J Med Genet 2019; 57:38-47. [PMID: 31519711 DOI: 10.1136/jmedgenet-2019-106030] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 07/04/2019] [Accepted: 07/24/2019] [Indexed: 01/01/2023]
Abstract
BACKGROUND Fabry disease is a progressive multisystemic disease, which affects the kidney and cardiovascular systems. Various treatments exist but decisions on how and when to treat are contentious. The current marker for monitoring treatment is plasma globotriaosylsphingosine (lyso-Gb3), but it is not informative about the underlying and developing disease pathology. METHODS We have created a urine proteomic assay containing a panel of biomarkers designed to measure disease-related pathology which include the inflammatory system, lysosome, heart, kidney, endothelium and cardiovascular system. Using a targeted proteomic-based approach, a series of 40 proteins for organ systems affected in Fabry disease were multiplexed into a single 10 min multiple reaction monitoring Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) assay and using only 1 mL of urine. RESULTS Six urinary proteins were elevated in the early-stage/asymptomatic Fabry group compared with controls including albumin, uromodulin, α1-antitrypsin, glycogen phosphorylase brain form, endothelial protein receptor C and intracellular adhesion molecule 1. Albumin demonstrated an increase in urine and could indicate presymptomatic disease. The only protein elevated in the early-stage/asymptomatic patients that continued to increase with progressive multiorgan involvement was glycogen phosphorylase brain form. Podocalyxin, fibroblast growth factor 23, cubulin and Alpha-1-Microglobulin/Bikunin Precursor (AMBP) were elevated only in disease groups involving kidney disease. Nephrin, a podocyte-specific protein, was elevated in all symptomatic groups. Prosaposin was increased in all symptomatic groups and showed greater specificity (p<0.025-0.0002) according to disease severity. CONCLUSION This work indicates that protein biomarkers could be helpful and used in conjunction with plasma lyso-Gb3 for monitoring of therapy or disease progression in patients with Fabry disease.
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Affiliation(s)
- Ivan D Doykov
- Centre for Inborn Errors of Metabolism, UCL Institute of Child Health Library, London, UK
| | - Wendy E Heywood
- Centre for Inborn Errors of Metabolism, UCL Institute of Child Health Library, London, UK.,NIHR Great Ormond Street Biomedical Research Centre, Great Ormond Street Hospital and UCL Great Ormond Street Institute of Child Health, London, UK
| | - Valeria Nikolaenko
- Centre for Inborn Errors of Metabolism, UCL Institute of Child Health Library, London, UK.,NIHR Great Ormond Street Biomedical Research Centre, Great Ormond Street Hospital and UCL Great Ormond Street Institute of Child Health, London, UK
| | - Justyna Śpiewak
- Centre for Inborn Errors of Metabolism, UCL Institute of Child Health Library, London, UK
| | - Jenny Hällqvist
- Centre for Inborn Errors of Metabolism, UCL Institute of Child Health Library, London, UK
| | - Peter Theodore Clayton
- Centre for Inborn Errors of Metabolism, UCL Institute of Child Health Library, London, UK
| | - Philippa Mills
- Centre for Inborn Errors of Metabolism, UCL Institute of Child Health Library, London, UK
| | - David G Warnock
- Division of Nephrology, Department of Medicine, University of Alabama, Birmingham, Alabama, USA
| | - Albina Nowak
- Department of Endocrinology and Clinical Nutrition, University Hospital Zurich and University of Zurich, Raemistrasse, Zurich, Switzerland
| | - Kevin Mills
- Centre for Inborn Errors of Metabolism, UCL Institute of Child Health Library, London, UK .,NIHR Great Ormond Street Biomedical Research Centre, Great Ormond Street Hospital and UCL Great Ormond Street Institute of Child Health, London, UK
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Hwang VJ, Ulu A, van Hoorebeke J, Weiss RH. Biomarkers in IgA nephropathy. Biomark Med 2014; 8:1263-77. [DOI: 10.2217/bmm.14.92] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
IgA nephropathy is the most common primary glomerulonephritis and presents with gross hematuria and upper respiratory infection, with slow progression to end-stage renal disease in up to 50% of affected patients. Kidney biopsies are the gold standard method of diagnosis and frequently are not performed as the majority of individuals are asymptomatic. Thus, there is a need to discover and validate prognostic and predictive biomarkers that can be noninvasively obtained and are specific to this disease. Here we discuss the current state of research in this area and examine validated and clinically promising biofluid and tissue biomarkers of IgA nephropathy.
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Affiliation(s)
- Vicki J Hwang
- Division of Nephrology, Department of Internal Medicine, Genome & Biomedical Sciences Building, Room 6312, University of California, Davis, CA 95616, USA
- Integrative Genetics & Genomics Graduate Group, 227 Life Sciences, University of California, Davis, CA 95616, USA
| | - Arzu Ulu
- Division of Nephrology, Department of Internal Medicine, Genome & Biomedical Sciences Building, Room 6312, University of California, Davis, CA 95616, USA
| | - Justin van Hoorebeke
- Division of Nephrology, Department of Internal Medicine, Genome & Biomedical Sciences Building, Room 6312, University of California, Davis, CA 95616, USA
- Molecular, Cellular & Integrative Physiology, 227 Life Sciences, University of California, Davis, CA 95616, USA
| | - Robert H Weiss
- Division of Nephrology, Department of Internal Medicine, Genome & Biomedical Sciences Building, Room 6312, University of California, Davis, CA 95616, USA
- Integrative Genetics & Genomics Graduate Group, 227 Life Sciences, University of California, Davis, CA 95616, USA
- Molecular, Cellular & Integrative Physiology, 227 Life Sciences, University of California, Davis, CA 95616, USA
- Cancer Center, University of California, Davis, CA 95616, USA
- Medical Service, Mather VA Medical Center, Sacramento, CA, USA
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Khurana S, Bruggeman LA, Kao HY. Nuclear hormone receptors in podocytes. Cell Biosci 2012; 2:33. [PMID: 22995171 PMCID: PMC3543367 DOI: 10.1186/2045-3701-2-33] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 08/10/2012] [Indexed: 11/14/2022] Open
Abstract
Nuclear receptors are a family of ligand-activated, DNA sequence-specific transcription factors that regulate various aspects of animal development, cell proliferation, differentiation, and homeostasis. The physiological roles of nuclear receptors and their ligands have been intensively studied in cancer and metabolic syndrome. However, their role in kidney diseases is still evolving, despite their ligands being used clinically to treat renal diseases for decades. This review will discuss the progress of our understanding of the role of nuclear receptors and their ligands in kidney physiology with emphasis on their roles in treating glomerular disorders and podocyte injury repair responses.
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Affiliation(s)
- Simran Khurana
- Department of Biochemistry, School of Medicine, Case Western Reserve University (CWRU) and the Comprehensive Cancer Center of CWRU, 10900 Euclid Avenue, Cleveland, Ohio 44106, USA.
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Abstract
Since its first description more than 40 years ago, IgA nephropathy has become the most common pattern of primary glomerulonephritis identified in all areas of the world where renal biopsy is routinely performed. This review discusses advances in our understanding of the pathogenesis of IgA nephropathy, principally focusing on work published in the past 5 years. It has been recognized for some time that one of the most consistent features of IgA nephropathy is an alteration in the complement of serum IgA1 O-glycoforms, with an overrepresentation of poorly galactosylated IgA1 O-glycoforms both in the serum and mesangial deposits of patients with IgA nephropathy. New data suggest that poorly galactosylated IgA1 O-glycoforms might act either as autoantigens driving the formation of glycan-specific antibodies, or antigens for cross-reactive antimicrobial antibodies. Formation of these circulating and mesangial IgA-containing immune complexes appears pivotal to the pathogenesis of IgA nephropathy and there is strong in vitro data to support their role in activation of mesangial cells, induction of podocyte injury, and activation of proximal tubular epithelial cells. Genetic factors are likely to influence many facets of pathogenesis both in primary and familial IgA nephropathy, however, to date work in this area has failed to identify consistent candidate genes.
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Affiliation(s)
- Jonathan Barratt
- The John Walls Renal Unit, Leicester General Hospital and Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom
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Ozaltin F, Ibsirlioglu T, Taskiran E, Baydar D, Kaymaz F, Buyukcelik M, Kilic B, Balat A, Iatropoulos P, Asan E, Akarsu N, Schaefer F, Yilmaz E, Bakkaloglu A. Disruption of PTPRO causes childhood-onset nephrotic syndrome. Am J Hum Genet 2011; 89:139-47. [PMID: 21722858 DOI: 10.1016/j.ajhg.2011.05.026] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 05/24/2011] [Accepted: 05/25/2011] [Indexed: 11/26/2022] Open
Abstract
Idiopathic nephrotic syndrome (INS) is a genetically heterogeneous group of disorders characterized by proteinuria, hypoalbuminemia, and edema. Because it typically results in end-stage kidney disease, the steroid-resistant subtype (SRNS) of INS is especially important when it occurs in children. The present study included 29 affected and 22 normal individuals from 17 SRNS families; genome-wide analysis was performed with Affymetrix 250K SNP arrays followed by homozygosity mapping. A large homozygous stretch on chromosomal region 12p12 was identified in one consanguineous family with two affected siblings. Direct sequencing of protein tyrosine phosphatase receptor type O (PTPRO; also known as glomerular epithelial protein-1 [GLEPP1]) showed homozygous c.2627+1G>T donor splice-site mutation. This mutation causes skipping of the evolutionarily conserved exon 16 (p.Glu854_Trp876del) at the RNA level. Immunohistochemistry with GLEPP1 antibody showed a similar staining pattern in the podocytes of the diseased and control kidney tissues. We used a highly polymorphic intragenic DNA marker-D12S1303-to search for homozygosity in 120 Turkish and 13 non-Turkish individuals in the PodoNet registry. This analysis yielded 17 candidate families, and a distinct homozygous c.2745+1G>A donor splice-site mutation in PTPRO was further identified via DNA sequencing in a second Turkish family. This mutation causes skipping of exon 19, and this introduces a premature stop codon at the very beginning of exon 20 (p.Asn888Lysfs*3) and causes degradation of mRNA via nonsense-mediated decay. Immunohistochemical analysis showed complete absence of immunoreactive PTPRO. Ultrastructural alterations, such as diffuse foot process fusion and extensive microvillus transformation of podocytes, were observed via electron microscopy in both families. The present study introduces mutations in PTPRO as another cause of autosomal-recessive nephrotic syndrome.
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Focal segmental glomerulosclerosis plays a major role in the progression of IgA nephropathy. II. Light microscopic and clinical studies. Kidney Int 2010; 79:643-654. [PMID: 21178978 DOI: 10.1038/ki.2010.460] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
It is well known that lesions morphologically identical with focal segmental glomerulosclerosis (FSGS) may appear in IgA nephropathy (IgAN). Capsular adhesions without underlying abnormalities in the tuft, often the first sign of FSGS, are frequent in IgAN. In this retrospective study, a new cohort of 128 adult patients with IgAN was used to validate the new Oxford classification system of IgAN, and shown to have highly significant associations with clinical and outcome parameters. We then used these patients to determine the extent to which IgAN could be accounted for in terms of FSGS. Some form of lesion consistent with FSGS, notably hyalinosis and collapsing glomerulopathy, was found in 101 of these patients. No glomerular lesions were found in 16 patients, and 11 had mild lesions not definable as FSGS. Those with FSGS had significantly worse renal survival at 80 months than those without. Comparison of pure forms of FSGS (excluding collapsing glomerulopathy) with cases of FSGS having other glomerular lesions (mesangial hyperplasia, endocapillary hypercellularity, glomerular necroses, extracapillary proliferation) revealed that those with FSGS and other superimposed lesions did significantly worse than cases of pure FSGS at 80 months following diagnosis. Importantly, patients with pure FSGS had relatively poor survival even without other superimposed glomerular abnormalities. Thus, the majority of cases of IgAN can be interpreted as representing one or another variant of FSGS. Hence, interpreting IgAN in terms of FSGS emphasizes the role that podocyte lesions may play in the pathogenesis and progression of this disease.
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Hill GS, Karoui KE, Karras A, Mandet C, Van Huyen JPD, Nochy D, Bruneval P. Focal segmental glomerulosclerosis plays a major role in the progression of IgA nephropathy. I. Immunohistochemical studies. Kidney Int 2010; 79:635-642. [PMID: 21160460 DOI: 10.1038/ki.2010.466] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
IgA nephropathy (IgAN) often shows lesions morphologically identical with those of focal segmental glomerulosclerosis (FSGS). In order to determine the possible role of FSGS in IgAN lesions, we measured glomerular capsular adhesions, often the first step toward FSGS, in biopsies from 127 patients with IgAN, 100 with lupus nephritis, and 26 with primary FSGS. Capsular adhesions with no lesions in the underlying tuft, consistent with podocyte abnormality or loss, were found regularly in FSGS and IgAN, but infrequently in lupus. Fifteen biopsies of patients with IgAN were studied immunohistochemically using markers for podocytes, Bowman's parietal epithelial cells, proliferating cells, and macrophages. Cytokeratins CK-8 and C2562 differentiated normal podocytes (negative) from parietal epithelial cells (variably positive). There was focal loss of the podocyte markers synaptopodin, glomerular epithelial protein 1 (GLEPP-1), nephrin, and vascular endothelial growth factor (VEGF), particularly at sites of capsular adhesions in otherwise histologically normal glomeruli. Cells displaying the parietal epithelial cell markers PAX2 (paired box gene 2) and the cytokeratins were also positive for the proliferating cell marker, proliferating cell nuclear antigen. These cells gathered at sites of adhesion, and in response to active lesions in the tuft, grew inward along the adhesion onto the tuft, forming a monolayer positive for parietal markers and the podocyte marker Wilms tumor protein-1 (WT-1). These cells deposited a layer of collagen over the sclerosing tuft. Thus, all biopsies of patients with IgAN had changes basically identical to those classically described in FSGS. Hence, our study strongly suggests that podocytopathy of a type similar to that in primary FSGS occurs frequently in IgAN.
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Affiliation(s)
- Gary S Hill
- Department of Pathology, Hôpital Européen Georges Pompidou, Paris, France.
| | | | - Alexandre Karras
- Department of Nephrology, Hôpital Européen Georges Pompidou, Paris, France
| | - Chantal Mandet
- Department of Pathology, Hôpital Européen Georges Pompidou, Paris, France
| | | | - Dominique Nochy
- Department of Pathology, Hôpital Européen Georges Pompidou, Paris, France
| | - Patrick Bruneval
- Department of Pathology, Hôpital Européen Georges Pompidou, Paris, France
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Abstract
Podocyte injury is a feature of glomerulopathies associated with proteinuria, which in turn has been used as a clinical prognostic factor for glomerular diseases. The goal of this study is to investigate the relationship between podocyte injury found in biopsied renal tissue and change of proteinuria in IgA nephropathy (IgAN). In all, 35 patients with biopsy-proven IgAN and proteinuria (>1.0 g per 24 h) were enrolled in the IgAN group, while 8 patients with excision of renal harmatoma or carcinoma served as kidney controls (Control). Immunohistochemistry was applied to detect the expression of nestin, cell-cycle regulatory protein p27, as well as complement C5b-9 and complement receptor 1 (CR1). Podocyte foot process width (FPW) and podocyte population in renal biopsied samples were measured by morphometric analysis. On the basis of the podocyte density (Nv), the IgAN patients were divided into podocytopenic group (n=17, Nv<57.10 /microm(3) x 10(6)) and normopodocytic group (n=18, Nv> or =57.10 /microm(3) x 10(6)). Changes of proteinuria were followed for 18 months after biopsy. Compared with the Control, IgAN glomeruli had reduced podocyte expression of p27 and nestin along with decreased podocyte number. IgAN glomeruli also showed activation of C5b-9 in mesangial and subepithelial areas with decreased CR1 expression in podocytes. The C5b-9 positivity was inversely correlated with the number of WT-1-positive podocytes. Although the magnitude of proteinuria at biopsy correlated with podocyte FPW (P<0.05), the change in the amount of proteinuria expressed as proteinuria progression rate significantly correlated with the podocyte density. Thus, the normopodocytic group showed significantly lower proteinuria progression rate than the podocytopenic group regardless the comparable clinical features at biopsy and treatment regimen between the two groups. The results of this study indicate that, in IgAN, podocyte injury is involved in development of proteinuria and loss of podocytes predicts progression of the proteinuria. Complement activation may contribute to podocyte damage in IgAN.
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Aberrantly glycosylated IgA1 induces mesangial cells to produce platelet-activating factor that mediates nephrin loss in cultured podocytes. Kidney Int 2009; 77:417-27. [PMID: 20016469 DOI: 10.1038/ki.2009.473] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The reaction of mesangial cells with aberrantly glycosylated IgA1 has been implicated in the etiology of IgA nephropathy (IgAN). Tumor necrosis factor, which is assumed to mediate the interaction between mesangial cells and podocytes, also induces the expression of platelet-activating factor (PAF). In this study, we determined whether PAF affects the expression of nephrin (an adhesion molecule critical to glomerular permselectivity) and cytoskeletal F-actin organization in podocytes. We treated human mesangial cells with atypically glycosylated IgA1 either prepared in vitro or derived from the sera of patients with IgAN. We then prepared conditioned media from these cells and added them to cultured human podocytes in the presence of PAF receptor antagonists. Podocytes transfected to overexpress acetylhydrolase, the main catabolic enzyme of PAF, served as controls. Downregulation of nephrin expression and F-actin reorganization occurred when podocytes were cultured with mesangial cell-conditioned medium. Preincubation of podocytes with a PAF receptor antagonist prevented the loss and redistribution of nephrin. In control podocytes overexpressing acetylhydrolase, nephrin loss was abrogated. Our results suggest that atypically glycosylated IgA-induced PAF from mesangial cells is a mediator of podocyte changes, which, when more directly tested elsewhere, were found to be associated with proteinuria. Hence, it is possible that these in vitro findings may be relevant to the proteinuria of IgAN.
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Pathological predictors of prognosis in immunoglobulin A nephropathy: a review. Curr Opin Nephrol Hypertens 2009; 18:212-9. [PMID: 19300248 DOI: 10.1097/mnh.0b013e328329605c] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW To provide a review and discussion of histological prognostic indicators in immunoglobulin A (IgA) nephropathy (IgAN). RECENT FINDINGS A variety of histological parameters and classifications have been used to attempt to predict prognosis in patients with IgAN. Grading systems used thus far do not consistently provide a useful adjunct to clinical prognostic parameters. This may be due to the variety of grading systems used, to inconsistent patient recruitment processes, and to the use of actuarial renal survival as an end point. This has led to the development of a new IgAN classification proposal by the International IgA Nephropathy Network in conjunction with the Renal Pathological Society. Additional potential markers of disease progression currently under investigation include glomerular parameters such as number and size, markers of podocyte function and of complement activation, inflammatory infiltrates and mediators of tubulointerstitial fibrosis. SUMMARY There is a need for an internationally accepted, reproducible and clinically meaningful pathological classification of IgAN. Such a classification is currently being developed. By using only reproducible, single parameters and validating them on a large group of cases from all over the world, it is hoped that a useful clinically predictive tool will be developed.
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Skoberne A, Konieczny A, Schiffer M. Glomerular epithelial cells in the urine: what has to be done to make them worthwhile? Am J Physiol Renal Physiol 2008; 296:F230-41. [PMID: 18842819 DOI: 10.1152/ajprenal.90507.2008] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The significance of the native urine sediment in the differential of glomerular diseases needs no further comment. However, the question arises whether it could be useful to develop a more specific diagnostic approach to identify the origin of renal epithelial cells that can be detected in the urine sediments as well. Especially the detection of podocytes in the urine could be a valuable noninvasive method to get information about the disease activity or disease type and could be used as a follow-up after a biopsy in an outpatient setting. So far, there are only a few studies that analyzed the clinical relevance of renal epithelial cells in the urine systematically or prospectively. The reason for this could be the nature of the material since it will remain unclear whether detachment and changes in the urine milieu have a direct effect on the expression of marker proteins on the detected cells. Dedifferentiation or transdifferentiation of cells that goes along with changed marker expression is certainly also part of the underlying disease process. This review summarizes the available information on marker proteins that have been successfully used in the diagnostic of "podocytes" in the urine. Furthermore, it gives an overview of marker expression on podocytes in situ in development and disease and examines the role of glomerular epithelial shedding in the urine at the interface of basic science and clinical medicine.
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Affiliation(s)
- Andrej Skoberne
- Division of Nephrology, University Medical Centre Ljubljana, Ljublijana, Slovenia, Germany
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Lai KN, Leung JCK, Chan LYY, Saleem MA, Mathieson PW, Tam KY, Xiao J, Lai FM, Tang SCW. Podocyte injury induced by mesangial-derived cytokines in IgA nephropathy. Nephrol Dial Transplant 2008; 24:62-72. [PMID: 18685143 DOI: 10.1093/ndt/gfn441] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND We have previously documented that human mesangial cell (HMC)-derived tumour necrosis factor-alpha (TNF-alpha) is an important mediator involved in the glomerulo-tubular communication in the development of interstitial damage in IgA nephropathy (IgAN). With the strategic position of podocytes, we further examined the function of podocytes in IgAN. METHODS Podocyte markers were examined in renal tissues by immunofluorescence. In vitro experiments were conducted with podocytes cultured with polymeric IgA (pIgA) or conditioned medium prepared from HMC incubated with pIgA (IgA-HMC conditioned medium). RESULTS Glomerular immunostaining for nephrin or ezrin was significantly weaker in patients with IgAN. The immunostaining of IgA and nephrin was distinctly separate with no co-localization. In vitro experiments revealed no effect of pIgA on the expression of these podocyte proteins as IgA from IgAN patients did not bind to podocytes. In contrast, IgA conditioned medium prepared from IgAN patients down-regulated the expression of these podocyte proteins as well as other podocyte markers (podocin and synaptopodin) in cultured podocytes. The mRNA expression of nephrin, erzin, podocin but not synaptopodin correlated with the degree of proteinuria and creatinine clearance. The down-regulation was reproducible in podocytes cultured with TNF-alpha or transforming growth factor-beta (TGF-beta) at concentration comparable to that in the IgA-HMC conditioned medium. The expression of these podocyte proteins was restored partially with a neutralizing antibody against TNF-alpha or TGF-beta and fully with combination of both antibodies. CONCLUSION Our finding suggests podocyte markers are reduced in IgAN. An in vitro study implicates that humoral factors (predominantly TNF-alpha and TGF-beta) released from mesangial cells are likely to alter the glomerular permeability in the event of proteinuria and tubulointerstitial injury in IgAN.
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Affiliation(s)
- Kar Neng Lai
- Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong.
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