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Kovalik ME, Dacanay MA, Crowley SD, Hall G. Swollen Feet: Considering the Paradoxical Roles of Interleukins in Nephrotic Syndrome. Biomedicines 2024; 12:738. [PMID: 38672094 PMCID: PMC11048099 DOI: 10.3390/biomedicines12040738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 03/11/2024] [Accepted: 03/15/2024] [Indexed: 04/28/2024] Open
Abstract
Interleukins are a family of 40 bioactive peptides that act through cell surface receptors to induce a variety of intracellular responses. While interleukins are most commonly associated with destructive, pro-inflammatory signaling in cells, some also play a role in promoting cellular resilience and survival. This review will highlight recent evidence of the cytoprotective actions of the interleukin 1 receptor (IL-1R)- and common gamma chain receptor (IL-Rγc)-signaling cytokines in nephrotic syndrome (NS). NS results from the injury or loss of glomerular visceral epithelial cells (i.e., podocytes). Although the causes of podocyte dysfunction vary, it is clear that pro-inflammatory cytokines play a significant role in regulating the propagation, duration and severity of disease. Pro-inflammatory cytokines signaling through IL-1R and IL-Rγc have been shown to exert anti-apoptotic effects in podocytes through the phosphoinositol-3-kinase (PI-3K)/AKT pathway, highlighting the potential utility of IL-1R- and IL-Rγc-signaling interleukins for the treatment of podocytopathy in NS. The paradoxical role of interleukins as drivers and mitigators of podocyte injury is complex and ill-defined. Emerging evidence of the cytoprotective role of some interleukins in NS highlights the urgent need for a nuanced understanding of their pro-survival benefits and reveals their potential as podocyte-sparing therapeutics for NS.
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Affiliation(s)
- Maria E. Kovalik
- Division of Nephrology, Duke University, Durham, NC 27701, USA; (M.E.K.)
- Duke Molecular Physiology Institute, Duke University, Durham, NC 27710, USA
| | - Monique A. Dacanay
- Division of Nephrology, Duke University, Durham, NC 27701, USA; (M.E.K.)
- Duke Molecular Physiology Institute, Duke University, Durham, NC 27710, USA
| | - Steven D. Crowley
- Division of Nephrology, Duke University, Durham, NC 27701, USA; (M.E.K.)
| | - Gentzon Hall
- Division of Nephrology, Duke University, Durham, NC 27701, USA; (M.E.K.)
- Duke Molecular Physiology Institute, Duke University, Durham, NC 27710, USA
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2
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Raina R, Jothi S, Haffner D, Somers M, Filler G, Vasistha P, Chakraborty R, Shapiro R, Randhawa PS, Parekh R, Licht C, Bunchman T, Sethi S, Mangat G, Zaritsky J, Schaefer F, Warady B, Bartosh S, McCulloch M, Alhasan K, Swiatecka-Urban A, Smoyer WE, Chandraker A, Yap HK, Jha V, Bagga A, Radhakrishnan J. Post-transplant recurrence of focal segmental glomerular sclerosis: consensus statements. Kidney Int 2024; 105:450-463. [PMID: 38142038 DOI: 10.1016/j.kint.2023.10.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 10/03/2023] [Accepted: 10/17/2023] [Indexed: 12/25/2023]
Abstract
Focal segmental glomerular sclerosis (FSGS) is 1 of the primary causes of nephrotic syndrome in both pediatric and adult patients, which can lead to end-stage kidney disease. Recurrence of FSGS after kidney transplantation significantly increases allograft loss, leading to morbidity and mortality. Currently, there are no consensus guidelines for identifying those patients who are at risk for recurrence or for the management of recurrent FSGS. Our work group performed a literature search on PubMed/Medline, Embase, and Cochrane, and recommendations were proposed and graded for strength of evidence. Of the 614 initially identified studies, 221 were found suitable to formulate consensus guidelines for recurrent FSGS. These guidelines focus on the definition, epidemiology, risk factors, pathogenesis, and management of recurrent FSGS. We conclude that additional studies are required to strengthen the recommendations proposed in this review.
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Affiliation(s)
- Rupesh Raina
- Department of Nephrology, Akron Nephrology Associates/Cleveland Clinic Akron General Medical Center, Akron, Ohio, USA; Department of Nephrology, Akron Children's Hospital, Akron, Ohio, USA
| | - Swathi Jothi
- Department of Nephrology, Akron Nephrology Associates/Cleveland Clinic Akron General Medical Center, Akron, Ohio, USA
| | - Dieter Haffner
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany
| | - Michael Somers
- Division of Nephrology, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Guido Filler
- Department of Pediatrics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada; Department of Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada; Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada
| | - Prabhav Vasistha
- Department of Nephrology, Akron Nephrology Associates/Cleveland Clinic Akron General Medical Center, Akron, Ohio, USA
| | - Ronith Chakraborty
- Department of Nephrology, Akron Nephrology Associates/Cleveland Clinic Akron General Medical Center, Akron, Ohio, USA; Department of Nephrology, Akron Children's Hospital, Akron, Ohio, USA
| | - Ron Shapiro
- Recanati/Miller Transplantation Institute, The Mount Sinai Medical Center, New York, New York, USA
| | - Parmjeet S Randhawa
- Department of Pathology, Thomas E Starzl Transplant Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Rulan Parekh
- Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Christopher Licht
- Division of Pediatric Nephrology, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Timothy Bunchman
- Pediatric Nephrology and Transplantation, Children's Hospital of Richmond at Virginia Commonwealth University (VCU), Richmond, Virginia, USA
| | - Sidharth Sethi
- Pediatric Nephrology, Kidney Institute, Medanta, The Medicity Hospital, Gurgaon, Haryana, India
| | - Guneive Mangat
- Department of Nephrology, Akron Nephrology Associates/Cleveland Clinic Akron General Medical Center, Akron, Ohio, USA
| | - Joshua Zaritsky
- Division of Pediatric Nephrology, Nemours, A.I. duPont Hospital for Children, Wilmington, Delaware, USA
| | - Franz Schaefer
- Department of Pediatric Nephrology, University Children's Hospital Heidelberg, Heidelberg, Germany
| | - Bradley Warady
- Division of Nephrology, University of Missouri-Kansas City School of Medicine, Children's Mercy, Kansas City, Missouri, USA
| | - Sharon Bartosh
- Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin, USA
| | - Mignon McCulloch
- Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa
| | - Khalid Alhasan
- Nephrology Unit, Pediatrics Department, College of Medicine, King Saud University, Riyadh, Saudi Arabia; Pediatric Kidney Transplant Division, Organ Transplant Center, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Agnieszka Swiatecka-Urban
- University of Virginia Children's Hospital, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - William E Smoyer
- Center for Clinical and Translational Research and Division of Nephrology, Nationwide Children's Hospital, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Anil Chandraker
- Transplantation Research Center, Kidney and Pancreas Transplantation, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Hui Kim Yap
- Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore; Khoo Teck Puat-National University Children's Medical Institute, National University Hospital, Singapore, Singapore
| | - Vivekanand Jha
- George Institute for Global Health, University of New South Wales (UNSW), New Delhi, India; School of Public Health, Imperial College, London, UK; Prasanna School of Public Health, Manipal Academy of Higher Education, Manipal, India
| | - Arvind Bagga
- Division of Pediatric Nephrology, All India Institute of Medical Sciences, New Delhi, India
| | - Jai Radhakrishnan
- Department of Medicine (Nephrology), Columbia University Medical Center, New York, New York, USA.
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Al-Eisa AA, Al Rushood M, Kashyap S, Haider MZ. Tumor necrosis factor alpha gene polymorphism affects the pattern of idiopathic nephrotic syndrome in Kuwaiti Arab children. J Trop Pediatr 2023; 70:fmad047. [PMID: 38110745 DOI: 10.1093/tropej/fmad047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
OBJECTIVES TNF-α is a pro-inflammatory cytokine that has been implicated in many inflammatory diseases, but its association with idiopathic nephrotic syndrome (INS) is poorly understood. This study looked for an association of TNF-α gene polymorphisms with INS, as well as its effect on steroid responsiveness among Kuwaiti Arab children. METHODS Genotypes of the TNF-a gene polymorphisms were analyzed using polymerase chain reaction-restriction fragment length polymorphism in 151 INS Kuwaiti Arab patients and 64 age and sex-matched controls. Clinical data of all subjects were reviewed. RESULTS The heterozygous AG genotype was detected in 8.6% of INS patients compared 23.4% of the controls (p < 0.01). Comparing steroid responsiveness, AA genotype was significantly more common in steroid-sensitive nephrotic syndrome (SSNS) cases than steroid-resistant nephrotic syndrome (SRNS) patients (p = 0.001). However, AG genotype was significantly more common in SRNS patients compared to the SSNS cases (p = 0.001). No difference was found between these two subgroups in the GG genotype frequency. CONCLUSION AG genotype of TNF-a gene polymorphisms may be considered a suitable marker for INS disease among Kuwaiti children. Both AA and AG genotypes may be useful in predicting steroid responsiveness among these cases of Arab ethnicity. The findings might open the era for the use of genetic markers in the early treatment of NS.
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Affiliation(s)
- Amal A Al-Eisa
- Department of Pediatrics, College of Medicine-Kuwait University, Kuwait City, Safat 13110, Kuwait
| | - Maysoun Al Rushood
- Department of Pediatrics, College of Medicine-Kuwait University, Kuwait City, Safat 13110, Kuwait
| | - Sumedha Kashyap
- Department of Pediatrics, College of Medicine-Kuwait University, Kuwait City, Safat 13110, Kuwait
| | - Mohammad Z Haider
- Department of Pediatrics, College of Medicine-Kuwait University, Kuwait City, Safat 13110, Kuwait
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Bollain-y-Goytia JJ, Torres-Del-muro FDJ, Hernández-Martínez SP, Avalos-Díaz E, Herrera-Esparza R. suPAR and WT1 modify the adhesion of podocytes and are related to proteinuria in class IV lupus nephritis. J Transl Autoimmun 2023; 7:100216. [PMID: 37868110 PMCID: PMC10587709 DOI: 10.1016/j.jtauto.2023.100216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 10/02/2023] [Accepted: 10/06/2023] [Indexed: 10/24/2023] Open
Abstract
Introduction Lupus nephritis (LN) affects up to 60 % of the patients with Systemic Lupus Erythematosus (SLE) and renal damage progression is associated with proteinuria, caused in part by the integrity of the glomerular basement membrane (GBM) and by podocyte injury. The soluble urokinase plasminogen activator receptor (suPAR) and Wilms Tumor 1 (WT1) have been related to podocyte effacement and consequently with proteinuria which raises questions about its pathogenic role in LN. Objective Define whether suPAR levels and WT1 expression influence in podocyte anchorage destabilization in LN class IV. Materials and methods This is a cross-sectional study of cases and controls. We studied patients with SLE without renal involvement (n = 12), SLE and LN class IV with proteinuria ≤0.5 g/24 h (n = 12), LN class IV with proteinuria ≥0.5 g/24 h (n = 12) and compared them with renal tissue control (CR) (n = 12) and control sera (CS) (n = 12). The CR was integrated by cadaveric samples without SLE or renal involvement and the CS was integrated by healthy participants. The expression and cellular localization of WT1, urokinase-type plasminogen activator receptor (uPAR), ac-α-tubulin, vimentin, and β3-integrin was assessed by immunohistochemistry (IHC). The concentration of suPAR in serum was analyzed by enzyme-linked immunosorbent assay (ELISA). Results In patients with LN, the activation of anchoring proteins was increased, such as podocyte β3-integrin, as well as the acetylation of alpha-acetyl-tubulin and uPAR, in contrast to the decrease in vimentin; interestingly, the cellular localization of WT1 was cytoplasmic and the number of podocytes per glomerulus decreased. The concentrations of suPAR was increased in patients with LN. Conclusion The destabilization of podocyte anchorage modulated by β3-integrin activation, and tubulin acetylation, associated with decreased WT1 cytoplasmic expression, and increased suPAR levels could be involved in kidney damage in patients with LN class IV.
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Affiliation(s)
| | | | | | - Esperanza Avalos-Díaz
- Universidad Autónoma de Zacatecas, Department of Immunology, UACB. Guadalupe, Zacatecas, 98615, Mexico
| | - Rafael Herrera-Esparza
- Universidad Autónoma de Zacatecas, Department of Immunology, UACB. Guadalupe, Zacatecas, 98615, Mexico
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Hayward S, Parmesar K, Saleem MA. What is circulating factor disease and how is it currently explained? Pediatr Nephrol 2023; 38:3513-3518. [PMID: 36952039 PMCID: PMC10514121 DOI: 10.1007/s00467-023-05928-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/15/2023] [Accepted: 02/20/2023] [Indexed: 03/24/2023]
Abstract
Nephrotic syndrome (NS) consists of the clinical triad of hypoalbuminaemia, high levels of proteinuria and oedema, and describes a heterogeneous group of disease processes with different underlying drivers. The existence of circulating factor disease (CFD) as a driver of NS has been epitomised by a subset of patients who exhibit disease recurrence after transplantation, alongside laboratory work. Several circulating factors have been proposed and studied, broadly grouped into protease components such as soluble urokinase-type plasminogen activator (suPAR), hemopexin (Hx) and calcium/calmodulin-serine protease kinase (CASK), and other circulating proteases, and immune components such as TNF-α, CD40 and cardiotrophin-like cytokine-1 (CLC-1). While currently there is no definitive way of assessing risk of CFD pre-transplantation, promising work is emerging through the study of 'multi-omic' bioinformatic data from large national cohorts and biobanks.
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Affiliation(s)
- Samantha Hayward
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK.
- MRC Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK.
| | - Kevon Parmesar
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Moin A Saleem
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
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Chebotareva N, Cao V, Vinogradov A, Alentov I, Sergeeva N, Kononikhin A, Moiseev S. Preliminary study of anti-CD40 and ubiquitin proteasome antibodies in primary podocytopaties. Front Med (Lausanne) 2023; 10:1189017. [PMID: 37409273 PMCID: PMC10319126 DOI: 10.3389/fmed.2023.1189017] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Accepted: 06/05/2023] [Indexed: 07/07/2023] Open
Abstract
Background Minimal change disease and focal segmental glomerulosclerosis are primary podocytopathies that are clinically presented in adults presenting with severe nephrotic syndrome. The pathogenesis of these diseases is not clear and many questions remain to be answered. A new concept about the role of changes in the antigenic determinant of podocytes and the production of anti-podocyte antibodies that cause podocyte damage is being developed. The aim of the study is to evaluate the levels of anti-CD40 and anti-ubiquitin carboxyl-terminal hydrolase L1 (anti-UCH-L1) antibodies in patients with podocytopathies in comparison with other glomerulopathies. Methods One hundred and six patients with glomerulopathy and 11 healthy subjects took part in the study. A histological study revealed primary FSGS in 35 patients (genetic cases of FSGS and secondary FSGS in the absence of NS were excluded), 15 had MCD, 21 - MN, 13 - MPGN, 22 patients - IgA nephropathy. The effect of steroid therapy was evaluated in patients with podocytopathies (FSGS and MCD). The serum levels of anti-UCH-L1 and anti-CD40 antibodies were measured by ELISA before steroid treatment. Results The levels of anti-UCH-L1 antibodies were significantly higher in MCD patients and anti-CD40 antibodies were higher in MCD and FSGS than in the control group and other groups of glomerulopathies. In addition, the level of anti-UCH-L1 antibodies was higher in patients with steroid-sensitive FSGS and MCD, and anti-CD40 antibodies were lower than in patients with steroid-resistant FSGS. An increase in anti-UCH-L1 antibody levels above 6.44 ng/mL may be a prognostic factor of steroid-sensitivity. The ROC curve (AUC = 0.875 [95% CI 0.718-0.999]) for response to therapy showed a sensitivity of 75% and specificity of 87.5%. Conclusion An increase in the level of anti-UCH-L1 antibodies is specific for steroid-sensitive FSGS and MCD, while an increase in anti-CD40 antibodies - for steroid-resistant FSGS, compared with other glomerulopathies. It suggests that these antibodies could be a potential factor for differential diagnosis and treatment prognosis.
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Affiliation(s)
- Natalia Chebotareva
- Sechenov First Moscow State Medical University, Tareev Clinic of Internal Diseases, Moscow, Russia
| | - Venzsin Cao
- Sechenov First Moscow State Medical University, Tareev Clinic of Internal Diseases, Moscow, Russia
| | | | - Igor Alentov
- Hertsen Moscow Oncology Research Institute, Department of Prediction of Conservative Treatment Efficiency, Moscow, Russia
| | - Natalia Sergeeva
- Hertsen Moscow Oncology Research Institute, Department of Prediction of Conservative Treatment Efficiency, Moscow, Russia
| | | | - Sergey Moiseev
- Sechenov First Moscow State Medical University, Tareev Clinic of Internal Diseases, Moscow, Russia
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Staruschenko A, Ma R, Palygin O, Dryer SE. Ion channels and channelopathies in glomeruli. Physiol Rev 2023; 103:787-854. [PMID: 36007181 PMCID: PMC9662803 DOI: 10.1152/physrev.00013.2022] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/15/2022] [Accepted: 08/21/2022] [Indexed: 11/22/2022] Open
Abstract
An essential step in renal function entails the formation of an ultrafiltrate that is delivered to the renal tubules for subsequent processing. This process, known as glomerular filtration, is controlled by intrinsic regulatory systems and by paracrine, neuronal, and endocrine signals that converge onto glomerular cells. In addition, the characteristics of glomerular fluid flow, such as the glomerular filtration rate and the glomerular filtration fraction, play an important role in determining blood flow to the rest of the kidney. Consequently, disease processes that initially affect glomeruli are the most likely to lead to end-stage kidney failure. The cells that comprise the glomerular filter, especially podocytes and mesangial cells, express many different types of ion channels that regulate intrinsic aspects of cell function and cellular responses to the local environment, such as changes in glomerular capillary pressure. Dysregulation of glomerular ion channels, such as changes in TRPC6, can lead to devastating glomerular diseases, and a number of channels, including TRPC6, TRPC5, and various ionotropic receptors, are promising targets for drug development. This review discusses glomerular structure and glomerular disease processes. It also describes the types of plasma membrane ion channels that have been identified in glomerular cells, the physiological and pathophysiological contexts in which they operate, and the pathways by which they are regulated and dysregulated. The contributions of these channels to glomerular disease processes, such as focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, as well as the development of drugs that target these channels are also discussed.
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Affiliation(s)
- Alexander Staruschenko
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida
- Hypertension and Kidney Research Center, University of South Florida, Tampa, Florida
- James A. Haley Veterans Hospital, Tampa, Florida
| | - Rong Ma
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Oleg Palygin
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, Texas
- Department of Biomedical Sciences, Tilman J. Fertitta Family College of Medicine, University of Houston, Houston, Texas
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Tamura H. Trends in pediatric nephrotic syndrome. World J Nephrol 2021; 10:88-100. [PMID: 34631479 PMCID: PMC8477269 DOI: 10.5527/wjn.v10.i5.88] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 05/15/2021] [Accepted: 08/10/2021] [Indexed: 02/06/2023] Open
Abstract
Nephrotic syndrome (NS) is relatively common in children, with most of its histological types being minimal changed disease. Its etiology has long been attributed to lymphocyte (especially T-cell) dysfunction, while T-cell-mediated vascular hyperpermeability increases protein permeability in glomerular capillaries, leading to proteinuria and hypoproteinemia. Based on this etiology, steroids and immunosuppressive drugs that are effective against this disease have also been considered to correct T-cell dysfunction. However, in recent years, this has been questioned. The primary cause of NS has been considered damage to glomerular epithelial cells and podocyte-related proteins. Therefore, we first describe the changes in expression of molecules involved in NS etiology, and then describe the mechanism by which abnormal expression of these molecules induces proteinuria. Finally, we consider the mechanism by which infection causes the recurrence of NS.
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Affiliation(s)
- Hiroshi Tamura
- Department of Pediatrics, Kumamoto University, Kumamoto 8608556, Japan
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Podestà MA, Ponticelli C. Autoimmunity in Focal Segmental Glomerulosclerosis: A Long-Standing Yet Elusive Association. Front Med (Lausanne) 2020; 7:604961. [PMID: 33330569 PMCID: PMC7715033 DOI: 10.3389/fmed.2020.604961] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 10/26/2020] [Indexed: 01/17/2023] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a histological term that describes a pathologic renal entity affecting both adults and children, with a wide array of possible underlying etiologies. Podocyte damage with scarring, the hallmark of this condition, leads to altered permeability of the glomerular barrier, which may result in massive proteinuria and relentless renal function deterioration. A definite cause of focal segmental glomerulosclerosis can be confirmed in a minority of cases, while most forms have been traditionally labeled as primary or idiopathic. Despite this definition, increasing evidence indicates that primary forms are a heterogenous group rather than a single disease entity: several circulating factors that may affect glomerular permeability have been proposed as potential culprits, and both humoral and cellular immunity have been implicated in the pathogenesis of the disease. Consistently, immunosuppressive drugs are considered as the cornerstone of treatment for primary focal segmental glomerulosclerosis, but response to these agents and long-term outcomes are highly variable. In this review we provide a summary of historical and recent advances on the pathogenesis of primary focal segmental glomerulosclerosis, focusing on implications for its differential diagnosis and treatment.
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10
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Chebotareva NV, Vinogradov AA, Gindis AA, Bobkova IN, Cao W, Lysenko LV. [The balance of proinflammatory cytokines and Treg cells in chronic glomerulonephritis]. TERAPEVT ARKH 2020; 92:46-52. [PMID: 33346492 DOI: 10.26442/00403660.2020.06.000671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Indexed: 11/22/2022]
Abstract
Chronic glomerulonephritis (CGN) is a disease with a steadily progressing course, which is based on inflammation with the activation of immune cells. The severity of the inflammatory reaction in the kidney tissue is determined by the balance of locally pro-inflammatory factors and protective mechanisms, which include anti-inflammatory cytokines and T-regulatory lymphocytes (Treg). The study of processes that can modulate the severity of inflammation in the kidney is of particular interest for understanding the basic patterns of CGN progression. AIM To determine the clinical significance of the Th17, Th1, and Treg cytokines in urine to assess the activity and progression of chronic glomerulonephritis with nephrotic syndrome (NS). MATERIALS AND METHODS The study included 98 patients with CGN 37 women and 61 men. Patients were divided into two groups according to the degree of CGN activity. Group I consisted of 51 patients with NS. In 21 subjects, a decrease in GFR60 ml/min was revealed. Group II included 47 patients with proteinuria from 1 to 3 g/day without NS. GFR60 ml/min/1.73 m2 was observed in 26 patients. A kidney biopsy was performed in 65 patients and the hystological diagnosis was verified: 20 had mesangioproliferative GN, 16 had membranous nephropathy, 18 had focal segmental glomerulosclerosis, and 11 had membranoproliferative GN. The control group consisted of 15 healthy people. The levels of IL-6, IL-10, IL-17, tumor necrosis factor a (TNF-a) in the urine were determined using enzyme-linked immunosorbent assay. The number of FoxP3-positive cells in the inflammatory interstitial infiltrate of the cortical layer was determined in 39 patients (in a biopsy sample in a 1.5 mm2 area). RESULTS In group of patients with CGN, there was an increase in the levels of Th17, Th1, and Treg cytokines in urine TNF-a and IL-10 compared with healthy individuals. An increase in the levels of IL-6 in the urine of patients with high clinical activity of CGN (with NS and renal dysfunction) was more pronounced than in patients with NS and normal renal function. There was a decrease in the number of Treg cells in the interstitium of the kidney and a decrease in the production of anti-inflammatory IL-10 in CGN patients with NS, compared with patients without NS. The most pronounced changes in the cytokine profile were observed in patients with FSGS with an increase in pro-inflammatory cytokines and a decrease in Treg in the kidney tissue/anti-inflammatory IL-10 in the urine. CONCLUSION An imbalance of cytokines characterized by an increased levels of pro-inflammatory IL-17, IL-6, TNF-a, and a reduced levels of anti-inflammatory IL-10 and T-regulatory cells in the kidney tissue is noted in patients with NS, especially with FSGS. Imbalance of cytokines reflects the high activity of CGN and the risk of the progression of the disease.
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Affiliation(s)
- N V Chebotareva
- Sechenov First Moscow State Medical University (Sechenov University)
| | | | - A A Gindis
- Sechenov First Moscow State Medical University (Sechenov University)
| | - I N Bobkova
- Sechenov First Moscow State Medical University (Sechenov University)
| | - W Cao
- Sechenov First Moscow State Medical University (Sechenov University)
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Wenyang Lishui Decoction Ameliorates Podocyte Injury in Membranous Nephropathy Rat and Cell Models by Regulating p53 and Bcl-2. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2020; 2020:6813760. [PMID: 32454867 PMCID: PMC7243012 DOI: 10.1155/2020/6813760] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 04/24/2020] [Indexed: 01/08/2023]
Abstract
Wenyang Lishui decoction (WYD) has been frequently used to treat patients with membranous nephropathy (MN) in China. Our previous study in vitro showed that WYD aqueous extract could alleviate F-actin reorganization of podocytes induced by serum from idiopathic membranous nephropathy (IMN) patients. This study aims to investigate the effects and molecular mechanisms of WYD on MN. MN rat models were induced by cationic bovine serum albumin. Experimental rats were divided into four groups: normal, model, WYD, and benazepril. The normal group consisted of normal rats receiving distilled water for four weeks, while the model, WYD, and benazepril groups consisted of MN rats receiving distilled water, 16.5 g/kg/day WYD aqueous extract, and 10 mg/kg/day benazepril, respectively. Alanine aminotransferase, kidney function, albumin, and 24 h urine total protein (UTP) were measured. Hematoxylin-eosin and electron microscopy analyses were performed. Mouse podocytes were induced to develop cell models by serum from IMN patients with antibody to the M-type phospholipase A2 receptor and spleen and kidney Yang deficiency syndrome. They were divided into five groups: control, model, 2 mg/ml WYD, 4 mg/ml WYD, and 8 mg/ml WYD. CCK-8 assays, flow cytometry, qRT-PCR, and Western blot analyses were performed. In the animal experiment, side effects of WYD were not found. Also, there was no significant difference in kidney function among the groups. In addition, UTP level was significantly reduced, and kidney histological damage was restored in both WYD and benazepril groups but difference in UTP level between them was not found. In the cell experiment, apoptosis rate was increased in the model group while it was decreased by coincubation with WYD. Besides, mRNA and protein levels of p53 were decreased, and those of Bcl-2 were increased by treatment using WYD. In conclusion, WYD could reduce proteinuria and ameliorate podocyte injury by regulating the expression of p53 and Bcl-2. The study is registered in the Chinese Clinical Trial Registry (ChiCTR-OCH-14005137).
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Nephrotic syndrome in a dish: recent developments in modeling in vitro. Pediatr Nephrol 2020; 35:1363-1372. [PMID: 30820702 PMCID: PMC7316697 DOI: 10.1007/s00467-019-4203-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 12/20/2018] [Accepted: 01/16/2019] [Indexed: 01/05/2023]
Abstract
Nephrotic syndrome is a heterogeneous disease, and one of the most frequent glomerular disorders among children. Depending on the etiology, it may result in end-stage renal disease and the need for renal replacement therapy. A dysfunctional glomerular filtration barrier, comprising of endothelial cells, the glomerular basement membrane and podocytes, characterizes nephrotic syndrome. Podocytes are often the primary target cells in the pathogenesis, in which not only the podocyte function but also their crosstalk with other glomerular cell types can be disturbed due to a myriad of factors. The pathophysiology of nephrotic syndrome is highly complex and studying molecular mechanisms in vitro requires state-of-the-art cell-based models resembling the in vivo situation and preferably a fully functional glomerular filtration barrier. Current advances in stem cell biology and microfluidic platforms have heralded a new era of three-dimensional (3D) cultures that might have the potential to recapitulate the glomerular filtration barrier in vitro. Here, we highlight the molecular basis of nephrotic syndrome and discuss requirements to accurately study nephrotic syndrome in vitro, including an overview of specific podocyte markers, cutting-edge stem cell organoids, and the implementation of microfluidic platforms. The development of (patho) physiologically relevant glomerular models will accelerate the identification of molecular targets involved in nephrotic syndrome and may be the harbinger of a new era of therapeutic avenues.
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13
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Sun L, Zou LX, Han YC, Zhu DD, Chen T, Wang J. Role of A20/TNFAIP3 deficiency in lupus nephritis in MRL/lpr mice. Clin Exp Nephrol 2019; 24:107-118. [PMID: 31811410 DOI: 10.1007/s10157-019-01826-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 11/20/2019] [Indexed: 10/25/2022]
Abstract
BACKGROUND The activation of the nuclear factor-κB (NF-κB) signaling pathway gives rise to inflammation in the pathogenesis of lupus nephritis (LN), with A20 serving as a negative feedback regulator and ubiquitin C‑terminal hydrolase L1 (UCH-L1) acting as a downstream target protein. However, their roles in the mechanism of LN remain undetermined. METHODS In the present study, the expression of A20 and UCH-L1, the activity of NF-κB and ubiquitin-proteasome system (UPS) were measured in MRL/lpr mice and A20 gene silenced podocytes. The severity of podocyte injury and immune complex deposits were detected by transmission electron microscopy. RESULTS The in vivo experiments revealed that A20 failed to terminate the activation of NF-κB, which was accompanied by UCH-L1 overexpression, ubiquitin accumulation, and glomerular injury in LN mice. Immunosuppression therapy did improve LN progression by attenuating A20 deficiency. In vitro experiments confirmed that tumor necrosis factor-α induced NF-κB activation, which led to UCH-L1 overexpression, UPS impairment, the upregulation of desmin and the downregulation of synaptopodin in A20 gene silenced podocytes. CONCLUSION Thus, the results of the present study suggest that A20 regulates UCH-L1 expression via the NF-κB signaling pathway and A20 deficiency might play an important role in LN pathogenesis. Therefore, the A20 protein may serve as a promising therapeutic target for LN.
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Affiliation(s)
- Ling Sun
- Department of Nephrology, Xuzhou Central Hospital, Medical College of Southeast University, Xuzhou, Jiangsu, People's Republic of China.
| | - Lu-Xi Zou
- Zhejiang University, Hangzhou, Zhejiang, People's Republic of China.
| | - Yu-Chen Han
- Institute of Nephrology, Zhongda Hospital, Medical College of Southeast University, Jiangsu, People's Republic of China
| | - Dong-Dong Zhu
- Institute of Nephrology, Zhongda Hospital, Medical College of Southeast University, Jiangsu, People's Republic of China
| | - Ting Chen
- Department of Nephrology, Xuzhou Central Hospital, Medical College of Southeast University, Xuzhou, Jiangsu, People's Republic of China
| | - Jie Wang
- Department of Pathology, Xuzhou Central Hospital, Medical College of Southeast University, Xuzhou, Jiangsu, People's Republic of China
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14
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Molecular stratification of idiopathic nephrotic syndrome. Nat Rev Nephrol 2019; 15:750-765. [DOI: 10.1038/s41581-019-0217-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2019] [Indexed: 01/03/2023]
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15
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Intrinsic tumor necrosis factor-α pathway is activated in a subset of patients with focal segmental glomerulosclerosis. PLoS One 2019; 14:e0216426. [PMID: 31095586 PMCID: PMC6522053 DOI: 10.1371/journal.pone.0216426] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 04/20/2019] [Indexed: 01/09/2023] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is frequently found in biopsies of patients with steroid resistant nephrotic syndrome (SRNS). The pathogenesis of SRNS/FSGS is often unknown and the disease will recur in up to 50% of patients post-transplant, indicating the presence of circulating podocyte-toxic factor(s). Several studies have reported clinical improvement after anti-TNFα therapy. However, prediction of the clinical outcome in SRNS/FSGS is difficult, and novel predictive biomarkers are needed. An image-based assay, which measures disassembly of focal adhesion complexes in cultured podocytes, was used to ascertain the presence of podocyte toxic activity in SRNS/FSGS sera. Expression of TNFα pathway genes was analysed in the Nephroseq FSGS cohort and in cultured podocytes treated with SRNS/FSGS sera. Podocyte toxic activity was detected in 48/96 SRNS/FSGS patients. It did not correlate with serum TNFα levels, age, sex, ethnicity or glomerular filtration rate. In ~25% of the toxic samples, the toxicity was strongly inhibited by blockade of TNFα signaling. Transcriptional profiling of human FSGS biopsies and podocytes treated with FSGS sera revealed significant increases in expression of TNFα pathway genes. We identified patients with serum podocyte toxic activity who may be at risk for FSGS recurrence, and those patients in whom serum podocyte toxicity may be reversed by TNFα blockade. Activation of TNFα pathway genes occurs in podocytes of FSGS patients suggesting a causative effect of this pathway in response to circulating factor(s). In vitro analyses of patient sera may stratify patients according to prognostic outcomes and potential responses to specific clinical interventions.
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Dryer SE, Roshanravan H, Kim EY. TRPC channels: Regulation, dysregulation and contributions to chronic kidney disease. Biochim Biophys Acta Mol Basis Dis 2019; 1865:1041-1066. [PMID: 30953689 DOI: 10.1016/j.bbadis.2019.04.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 12/20/2018] [Accepted: 01/06/2019] [Indexed: 12/13/2022]
Abstract
Mutations in the gene encoding canonical transient receptor potential-6 (TRPC6) channels result in severe nephrotic syndromes that typically lead to end-stage renal disease. Many but not all of these mutations result in a gain in the function of the resulting channel protein. Since those observations were first made, substantial work has supported the hypothesis that TRPC6 channels can also contribute to progression of acquired (non-genetic) glomerular diseases, including primary and secondary FSGS, glomerulosclerosis during autoimmune glomerulonephritis, and possibly in type-1 diabetes. Their regulation has been extensively studied, especially in podocytes, but also in mesangial cells and other cell types present in the kidney. More recent evidence has implicated TRPC6 in renal fibrosis and tubulointerstitial disease caused by urinary obstruction. Consequently TRPC6 is being extensively investigated as a target for drug discovery. Other TRPC family members are present in kidney. TRPC6 can form a functional heteromultimer with TRPC3, and it has been suggested that TRPC5 may also play a role in glomerular disease progression, although the evidence on this is contradictory. Here we review literature on the expression and regulation of TRPC6, TRPC3 and TRPC5 in various cell types of the vertebrate kidney, the evidence that these channels are dysregulated in disease models, and research showing that knock-out or pharmacological inhibition of these channels can reduce the severity of kidney disease. We also summarize several areas that remain controversial, and some of the large gaps of knowledge concerning the fundamental role of these proteins in regulation of renal function.
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Affiliation(s)
- Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA; Department of Internal Medicine, Division of Nephrology, Baylor College of Medicine, Houston, TX, USA.
| | - Hila Roshanravan
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
| | - Eun Young Kim
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
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17
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Koh KH, Cao Y, Mangos S, Tardi NJ, Dande RR, Lee HW, Samelko B, Altintas MM, Schmitz VP, Lee H, Mukherjee K, Peev V, Cimbaluk DJ, Reiser J, Hahm E. Nonimmune cell-derived ICOS ligand functions as a renoprotective αvβ3 integrin-selective antagonist. J Clin Invest 2019; 129:1713-1726. [PMID: 30747722 DOI: 10.1172/jci123386] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 02/07/2019] [Indexed: 12/16/2022] Open
Abstract
Soluble urokinase receptor (suPAR) is a circulatory molecule that activates αvβ3 integrin on podocytes, causes foot process effacement, and contributes to proteinuric kidney disease. While active integrin can be targeted by antibodies and small molecules, endogenous inhibitors haven't been discovered yet. Here we report what we believe is a novel renoprotective role for the inducible costimulator ligand (ICOSL) in early kidney disease through its selective binding to podocyte αvβ3 integrin. Contrary to ICOSL's immune-regulatory role, ICOSL in nonhematopoietic cells limited the activation of αvβ3 integrin. Specifically, ICOSL contains the arginine-glycine-aspartate (RGD) motif, which allowed for a high-affinity and selective binding to αvβ3 and modulation of podocyte adhesion. This binding was largely inhibited either by a synthetic RGD peptide or by a disrupted RGD sequence in ICOSL. ICOSL binding favored the active αvβ3 rather than the inactive form and showed little affinity for other integrins. Consistent with the rapid induction of podocyte ICOSL by inflammatory stimuli, glomerular ICOSL expression was increased in biopsies of early-stage human proteinuric kidney diseases. Icosl deficiency in mice resulted in an increased susceptibility to proteinuria that was rescued by recombinant ICOSL. Our work identified a potentially novel role for ICOSL, which serves as an endogenous αvβ3-selective antagonist to maintain glomerular filtration.
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Affiliation(s)
- Kwi Hye Koh
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Yanxia Cao
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Steve Mangos
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Nicholas J Tardi
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Ranadheer R Dande
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Ha Won Lee
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Beata Samelko
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Mehmet M Altintas
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Vincent P Schmitz
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Hyun Lee
- Center for Biomolecular Science and Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Kamalika Mukherjee
- Department of Medicine, Harvard Medical School and Division of Nephrology, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Vasil Peev
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - David J Cimbaluk
- Department of Pathology, Rush University Medical Center, Chicago, Illinois, USA
| | - Jochen Reiser
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Eunsil Hahm
- Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
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Use of genomic and functional analysis to characterize patients with steroid-resistant nephrotic syndrome. Pediatr Nephrol 2018; 33:1741-1750. [PMID: 29982877 DOI: 10.1007/s00467-018-3995-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 06/06/2018] [Accepted: 06/07/2018] [Indexed: 01/09/2023]
Abstract
BACKGROUND Children with genetic causes of steroid-resistant nephrotic syndrome (SRNS) usually do well after renal transplantation, while some with idiopathic SRNS show recurrence due to a putative podocyte-toxic factor. Distinguishing different forms of SRNS based on clinical criteria has been difficult. The aim of our study was to test a novel approach that allows categorization of patients into clinically useful subgroups. METHODS Seventeen patients with clinically confirmed SRNS were analyzed by next-generation sequencing (NGS) of 37 known SRNS genes and a functional assay of cultured human podocytes, which indirectly tests for toxicity of patients' sera by evidenced loss of podocyte focal adhesion complex (FAC) number. RESULTS We identified a pathogenic mutation in seven patients (41%). Sera from patients with monogenic SRNS caused mild loss of FAC number down to 73% compared to untreated controls, while sera from seven of the remaining ten patients with idiopathic SRNS caused significant FAC number loss to 43% (non-overlapping difference 30%, 95% CI 26-36%, P < 0.001). All patients with recurrent SRNS (n = 4) in the graft showed absence of podocyte gene mutations but significant FAC loss. Three patients had no mutation nor serum podocyte toxicity. CONCLUSIONS Our approach allowed categorization of patients into three subgroups: (1) patients with monogenic SRNS; (2) patients with idiopathic SRNS and marked serum podocyte toxicity; and (3) patients without identifiable genetic cause nor evidence of serum podocyte toxicity. Post-transplant SRNS recurrence risk appears to be low in groups 1 and 3, but high in group 2.
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Abstract
Chronic kidney disease (CKD) has become a significant public health concern, as it is associated with substantial morbidity. Prior research has evaluated multiple novel CKD biomarkers to supplement serum creatinine and proteinuria. The ultimate goal of this research is to find biomarkers that can be used to accurately predict CKD progression and to better time outpatient follow-up, and referral for transplant. Also, an optimal panel of biomarkers can augment the predictive value of proteinuria and serum creatinine by enriching patient enrollment in clinical trials. In this review, we discuss salient findings on 12 candidate plasma and urine biomarkers and their reported association with CKD. We explore the common pathways of CKD progression and the pathophysiologic processes of tubulointerstitial injury, inflammation, repair, and fibrosis that are potentially classified by specific biomarkers. We describe both pediatric and adult findings and highlight the paucity of pediatric research in CKD progression. It will be important for cohorts with longitudinal follow-up to evaluate these CKD biomarkers for potential use in pediatric clinical trials and routine CKD management.
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20
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Deriving and understanding the risk of post-transplant recurrence of nephrotic syndrome in the light of current molecular and genetic advances. Pediatr Nephrol 2018; 33:2027-2035. [PMID: 29022104 PMCID: PMC6153493 DOI: 10.1007/s00467-017-3793-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 08/22/2017] [Indexed: 12/31/2022]
Abstract
After renal transplantation, recurrence of the original disease is the second most common cause of graft loss, after rejection. The most dramatic manifestation of this phenomenon is in patients with nephrotic syndrome (NS). NS is a descriptive term describing a clinical picture centred on proteinuria arising from damage to the glomerular filtration barrier (GFB). There are many different drivers of that damage, ranging from immune dysregulation to genetic disorders and chronic disease/infections. The main categories in childhood are "idiopathic" (presumed immune mediated) and genetic NS, with further stratification of the idiopathic group according to steroid responses. A significant proportion of patients with NS progress to established renal failure, requiring transplantation, and one of the most difficult clinical scenarios faced by nephrologists is the recurrence of the original disease in up to 50% of patients, usually rapidly post-transplant. This is thought to be the archetypal "circulating factor" disease, in which as yet unknown circulating plasma "factor(s)" in the recipient target the donor kidney. The ability to predict in advance which patients will suffer recurrence would enhance our ability to counsel patients and families, and potentially identify those patients before transplant for tailored immunosuppressive preparation. Until very recently, stratification based on clinical categorisations has been poor in being able to predict those patients in whom disease will recur, and laboratory biomarkers are yet to be adequately refined. However, by mapping our growing understanding of disease mechanisms to clinical phenotypes, and with greatly improved genetic diagnostics, we have made progress in being able to stratify patients more specifically, and allow better predictive algorithms to be developed. Using our knowledge of podocyte biology, circulating factor-induced specific biomarkers are also being tested. This review is aimed at outlining those advances, and suggesting how we can move further forward in both clinical and biological markers of disease type.
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21
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Kim EY, Roshanravan H, Dryer SE. Changes in podocyte TRPC channels evoked by plasma and sera from patients with recurrent FSGS and by putative glomerular permeability factors. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2342-2354. [PMID: 28629718 PMCID: PMC5557291 DOI: 10.1016/j.bbadis.2017.06.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 06/13/2017] [Accepted: 06/15/2017] [Indexed: 12/13/2022]
Abstract
Primary forms of focal and segmental glomerulosclerosis (FSGS) are driven by circulating factors that cause dysfunction or loss podocytes. Rare genetic forms of FSGS can be caused by mutations in TRPC6, which encodes a Ca2+-permeable cationic channel expressed in mesangial cells and podocytes; and NPHS2, which encodes podocin, a TRPC6-binding protein expressed in podocyte slit diaphragm domains. Here we observed that exposing immortalized mouse podocytes to serum or plasma from recurrent FSGS patients for 24h increased the steady-state cell-surface abundance of TRPC6, accompanied by an increase in currents through endogenous TRPC6 channels evoked by a hypoosmotic stretch stimulus. These effects were mimicked by the soluble urokinase receptor (suPAR) and by tumor necrosis factor (TNF), circulating factors implicated in nephrotic syndromes. Most but not all of the recurrent FSGS plasma samples that we examined also caused a loss of podocin over a period of several hours. The loss of podocin was also seen following exposure to suPAR but not TNF. However, TNF increased the effects of suPAR on TRPC6 and podocin, and TNF and suPAR are required for the full effects of one of the recurrent FSGS plasma samples. The actions of FSGS plasma, suPAR and TNF on surface abundance of TRPC6 were blocked by cilengitide, an inhibitor of αvβ3-integrin signaling. These data suggest that primary FSGS is a heterogeneous condition mediated by multiple circulating factors, and support TRPC6 and αvβ3-integrin as potential therapeutic targets.
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Affiliation(s)
- Eun Young Kim
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
| | - Hila Roshanravan
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
| | - Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA; Department of Medicine, Division of Nephrology, Baylor College of Medicine, Houston, TX, USA.
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22
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Peruzzi L, Albiani R, Giancaspero K. Plasma exchange in kidney transplantation: Still a valuable option for nephrotic syndrome recurrence. Transfus Apher Sci 2017; 56:525-530. [PMID: 28830667 DOI: 10.1016/j.transci.2017.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
About 30% of the cases of steroid resistant nephrotic syndrome display a genetically determined disease and will not recur after kidney transplant; the other cases with fully or partially immunological pathogenesis display a high risk of post transplant recurrence. Although lots of studies were carried out in the last 50 years the pathogenetic mechanism is still obscure and the therapeutic approach mostly empirical. The cornerstones principles of the therapies are based on removal of a still undefined "permeability factor" through plasma-exchange or other apheresis techniques and inhibition of its synthesis by the immunological system through different drugs. The probability of successfully inducing persistant remission is nowadays around 30%through the different schemes experimented so far which mostly include plasmapheresis. Rituximab in the last years has significantly increased the efficacy of the treatments. Non responders are rapidly evolving to graft loss and will most probably recur also in subsequent transplant. Apart from genetics no other risk factors are predictive for recurrence.
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Affiliation(s)
- Licia Peruzzi
- Pediatric Nephrology Unit, Regina Margherita Children's Hospital, Città della Salute e della Scienza di Torino, Turin, Italy.
| | - Roberto Albiani
- Apheresis Unit, Regina Margherita Children's Hospital, Città della Salute e della Scienza di Torino, Turin, Italy
| | - Karol Giancaspero
- Apheresis Unit, Regina Margherita Children's Hospital, Città della Salute e della Scienza di Torino, Turin, Italy
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Madanchi N, Bitzan M, Takano T. Rituximab in Minimal Change Disease: Mechanisms of Action and Hypotheses for Future Studies. Can J Kidney Health Dis 2017; 4:2054358117698667. [PMID: 28540057 PMCID: PMC5433659 DOI: 10.1177/2054358117698667] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 11/23/2016] [Indexed: 12/13/2022] Open
Abstract
Treatment with rituximab, a monoclonal antibody against the B-lymphocyte surface protein CD20, leads to the depletion of B cells. Recently, rituximab was reported to effectively prevent relapses of glucocorticoid-dependent or frequently relapsing minimal change disease (MCD). MCD is thought to be T-cell mediated; how rituximab controls MCD is not understood. In this review, we summarize key clinical studies demonstrating the efficacy of rituximab in idiopathic nephrotic syndrome, mainly MCD. We then discuss immunological features of this disease and potential mechanisms of action of rituximab in its treatment based on what is known about the therapeutic action of rituximab in other immune-mediated disorders. We believe that studies aimed at understanding the mechanisms of action of rituximab in MCD will provide a novel approach to resolve the elusive immune pathophysiology of MCD.
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Affiliation(s)
- Nima Madanchi
- Division of Nephrology, Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada
| | - Martin Bitzan
- Division of Nephrology, Department of Pediatrics, Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada
| | - Tomoko Takano
- Division of Nephrology, Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada
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Abstract
Idiopathic nephrotic syndrome (INS) is one of the most common glomerular diseases in children and adults, and the central event is podocyte injury. INS is a heterogeneous disease, and treatment is largely empirical and in many cases unsuccessful, and steroids are the initial mainstay of therapy. Close to 70% of children with INS have some response to steroids and are labelled as steroid-‘sensitive’, and the rest as steroid-‘resistant’ (also termed focal segmental glomerulosclerosis), and single-gene mutations underlie a large proportion of the latter group. The burden of morbidity is enormous, both to patients with lifelong chronic disease and to health services, particularly in managing dialysis and transplantation. The target cell of nephrotic syndrome is the glomerular podocyte, and podocyte biology research has exploded over the last 15 years. Major advances in genetic and biological understanding now put clinicians and researchers at the threshold of a major reclassification of the disease and testing of targeted therapies both identified and novel. That potential is based on complete genetic analysis, deep clinical phenotyping, and the introduction of mechanism-derived biomarkers into clinical practice. INS can now be split off into those with a single-gene defect, of which currently at least 53 genes are known to be causative, and the others. Of the others, the majority are likely to be immune-mediated and caused by the presence of a still-unknown circulating factor or factors, and whether there is a third (or more) mechanistic group or groups remains to be discovered. Treatment is therefore now being refined towards separating out the monogenic cases to minimise immunosuppression and further understanding how best to stratify and appropriately direct immunosuppressive treatments within the immune group. Therapies directed specifically towards the target cell, the podocyte, are in their infancy but hold considerable promise for the near future.
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Affiliation(s)
| | - Moin Saleem
- University of Bristol, Bristol Royal Hospital for Children, Bristol, UK
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25
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Soluble Urokinase Receptors in Focal Segmental Glomerulosclerosis: A Review on the Scientific Point of View. J Immunol Res 2016; 2016:2068691. [PMID: 27504461 PMCID: PMC4967695 DOI: 10.1155/2016/2068691] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 06/12/2016] [Indexed: 12/17/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is one of the primary glomerular disorders in both children and adults which can progress to end-stage renal failure. Although there are genetic and secondary causes, circulating factors have also been regarded as an important factor in the pathogenesis of FSGS, because about 40% of the patients with FSGS have recurrence after renal transplantation. Soluble urokinase-type plasminogen activator receptor (suPAR) is a soluble form of uPAR, which is a membrane-bound protein linked to GPI in various immunologically active cells, including podocytes. It has recently been suggested as a potential circulating factor in FSGS by in vitro podocyte experiments, in vivo mice models, and human studies. However, there have also been controversies on this issue, because subsequent studies showed conflicting results. suPAR levels were also increased in patients with other glomerular diseases and were inversely correlated with estimated glomerular filtration rate. Nevertheless, there has been no balanced review on this issue. In this review, we compare the conflicting data on the involvement of suPAR in the pathogenesis of FSGS and shed light on interpretation by taking into account many points and the potential variables and confounders influencing serum suPAR levels.
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Abstract
Minimal change disease (MCD) is an important cause of nephrotic syndrome and is characterized by massive proteinuria and hypoalbuminemia, resulting in edema and hypercholesterolemia. The podocyte plays a key role in filtration and its disruption results in a dramatic loss of function leading to proteinuria. Immunologic disturbance has been suggested in the pathogenesis of MCD. Because of its clinical features, such as recurrent relapse/remission course, steroid response in most patients, and rare familial cases, a genetic defect has been thought to be less likely in MCD. Recent progress in whole-exome sequencing reveals pathogenic mutations in familial cases in steroid-sensitive nephrotic syndrome (SSNS) and sheds light on possible mechanisms and key molecules in podocytes in MCD. On the other hand, in the majority of cases, the existence of circulating permeability factors has been implicated along with T lymphocyte dysfunction. Observations of benefit with rituximab added B cell involvement to the disease. Animal models are unsatisfactory, and the humanized mouse may be a good model that well reflects MCD pathophysiology to investigate suggested “T cell dysfunction” directly related to podocytes
in vivo. Several candidate circulating factors and their effects on podocytes have been proposed but are still not sufficient to explain whole mechanisms and clinical features in MCD. Another circulating factor disease is focal segmental glomerulosclerosis (FSGS), and it is not clear if this is a distinct entity, or on the same spectrum, implicating the same circulating factor(s). These patients are mostly steroid resistant and often have a rapid relapse after transplantation. In clinical practice, predicting relapse or disease activity and response to steroids is important and is an area where novel biomarkers can be developed based on our growing knowledge of podocyte signaling pathways. In this review, we discuss recent findings in genetics and podocyte biology in MCD.
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Affiliation(s)
- Moin A Saleem
- Paediatric Renal Medicine, University of Bristol, Bristol, UK; Children's Renal Unit, Bristol Royal Hospital for Children, Bristol, UK
| | - Yasuko Kobayashi
- Paediatric Renal Medicine, University of Bristol, Bristol, UK; Department of Pediatrics, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
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Messina M, Gallo E, Mella A, Pagani F, Biancone L. Update on the treatment of focal segmental glomerulosclerosis in renal transplantation. World J Transplant 2016; 6:54-68. [PMID: 27011905 PMCID: PMC4801805 DOI: 10.5500/wjt.v6.i1.54] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 12/22/2015] [Accepted: 01/22/2016] [Indexed: 02/05/2023] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) represents one of the most severe glomerular diseases, with frequent progression to end-stage renal disease and a high rate of recurrence in renal allografts (30%-50%). Recurrent FSGS portends a negative outcome, with the hazard ratio of graft failure being two-fold higher then that of other glomerulonephritis. Two patterns of clinical presentations are observed: Early recurrence, which is characterized by massive proteinuria within hours to days after implantation of the renal graft, and late recurrence, which occurs several months or years after the transplantation. Many clinical conditions have been recognized as risk factors for recurrence, including younger age, rapid progression of the disease to end-stage renal disease on native kidneys, and loss of previous renal allografts due to recurrence. However, much less is known about the incidence and risk factors of the so-called “de novo” type of FSGS, for which sufferers are transplanted patients without disease on native kidneys; but, rapid development of allograft failure is frequently observed. Management of both forms is challenging, and none of the approaches proposed to date have been demonstrated as consistently beneficial or effective. In the present review we report an update on the available therapeutic strategies for FSGS in renal transplantation within the context of a critical overview of the current literature.
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28
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Abstract
Podocytes are highly specialized cells of the kidney glomerulus that wrap around capillaries and that neighbor cells of the Bowman’s capsule. When it comes to glomerular filtration, podocytes play an active role in preventing plasma proteins from entering the urinary ultrafiltrate by providing a barrier comprising filtration slits between foot processes, which in aggregate represent a dynamic network of cellular extensions. Foot processes interdigitate with foot processes from adjacent podocytes and form a network of narrow and rather uniform gaps. The fenestrated endothelial cells retain blood cells but permit passage of small solutes and an overlying basement membrane less permeable to macromolecules, in particular to albumin. The cytoskeletal dynamics and structural plasticity of podocytes as well as the signaling between each of these distinct layers are essential for an efficient glomerular filtration and thus for proper renal function. The genetic or acquired impairment of podocytes may lead to foot process effacement (podocyte fusion or retraction), a morphological hallmark of proteinuric renal diseases. Here, we briefly discuss aspects of a contemporary view of podocytes in glomerular filtration, the patterns of structural changes in podocytes associated with common glomerular diseases, and the current state of basic and clinical research.
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Affiliation(s)
- Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Mehmet M Altintas
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
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29
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Davin JC. The glomerular permeability factors in idiopathic nephrotic syndrome. Pediatr Nephrol 2016; 31:207-15. [PMID: 25925039 PMCID: PMC4689751 DOI: 10.1007/s00467-015-3082-x] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2014] [Revised: 02/25/2015] [Accepted: 02/27/2015] [Indexed: 12/19/2022]
Abstract
It is currently postulated that steroid-sensitive idiopathic nephrotic syndrome (SSNS) and steroid-resistant idiopathic nephrotic syndrome (SRNS), which are not related to the mutation of a gene coding for podocyte structures or for glomerular basement membrane proteins, result from a circulating factor affecting podocyte shape and function. T lymphocytes have for a long time been suspected to be involved in the pathophysiology of these diseases. The successful treatment of steroid-dependant nephrotic syndrome with rituximab suggests a potential role for B lymphocytes. Clinical and experimental data indicate roles for cytokines IL-13, TNFα, circulating cardiotrophin-like cytokine factor 1 (member of the IL-6 family), circulating hemopexin, radical oxygen species, and the soluble urokinase-type plasminogen activator receptor (suPAR) in the development of nephrotic syndrome. Podocyte metabolism modifications-leading to the overexpression of the podocyte B7-1antigen (CD 80), hypoactivity of the podocyte enzyme sphingomyelin phosphodiesterase acid-like 3 b (SMPDL3b), and to the podocyte production of a hyposialylated form of the angiopoietin-like 4 (Angptl4)-are mechanisms possibly involved in the changes in the podocyte cytoskeleton leading to SSNS and or SRNS. Different multifactorial pathophysiological mechanisms can be advocated for SSNS and SRNS. The present paper reviews the experimental and clinical data upon which the different hypotheses are based and reports their possible clinical applications.
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Affiliation(s)
- Jean-Claude Davin
- Emma Children's Hospital/ Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands. .,Queen Fabiola Academic Children's Hospital, Free University of Brussels, Brussels, Belgium. .,Pediatric Nephrology Department, Emma Children's Hospital/ Academic Medical Centre, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
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30
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Kachurina N, Chung CF, Benderoff E, Babayeva S, Bitzan M, Goodyer P, Kitzler T, Matar D, Cybulsky AV, Alachkar N, Torban E. Novel unbiased assay for circulating podocyte-toxic factors associated with recurrent focal segmental glomerulosclerosis. Am J Physiol Renal Physiol 2015; 310:F1148-56. [PMID: 26719363 DOI: 10.1152/ajprenal.00349.2015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 12/28/2015] [Indexed: 01/28/2023] Open
Abstract
Focal segmental glomerular sclerosis (FSGS) is an irreversible renal pathology characterized by podocyte detachment from the glomerular basement membrane, hyalinosis, and sclerosis. Clinically, it manifests with proteinuria and progressive loss of glomerular filtration. Primary idiopathic FSGS can occur in isolation and frequently progresses to end-stage renal disease, requiring dialysis or kidney transplantation. In 30-50% of these patients, proteinuria and FSGS recur in the renal allograft, suggesting the presence of a podocyte-toxic factor(s) in the recipient's serum. Currently, there is no reliable way to quantify the serum activity or predict the subset of FSGS patients at risk for recurrence after transplantation. We describe a novel in vitro method that measures the podocyte-toxic activity of sera from FSGS patients using cultured human podocytes; we compare this with the effect of compounds such as adriamycin. Using immunofluorescence microscopy followed by computerized image-processing analysis, we show that incubation of human podocytes with adriamycin leads to a dose-dependent disassembly of focal adhesion complexes (FACs). We then demonstrate that sera from patients with posttransplant recurrent or idiopathic FSGS cause a similar FAC disturbance. In contrast, sera from nonrecurrent FSGS patients do not affect FACs. In some FSGS patients, toxic effects of serum can be prevented by blockade of the tumor necrosis factor-α pathway. We propose that this method may be useful as a diagnostic tool to identify FSGS patients with serum podocyte-toxic activity that presumably places them at increased risk for recurrence in the renal allograft.
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Affiliation(s)
- Nadezda Kachurina
- Department of Medicine, McGill University and McGill University Health Center, Montreal, Quebec, Canada
| | - Chen-Fang Chung
- Department of Medicine, McGill University and McGill University Health Center, Montreal, Quebec, Canada
| | - Erin Benderoff
- Department of Medicine, McGill University and McGill University Health Center, Montreal, Quebec, Canada
| | - Sima Babayeva
- Department of Medicine, McGill University and McGill University Health Center, Montreal, Quebec, Canada
| | - Martin Bitzan
- The Montreal Children's Hospital, Department of Paediatric Nephrology, McGill University Health Center, Montreal, Quebec, Canada
| | - Paul Goodyer
- The Montreal Children's Hospital, Department of Paediatric Nephrology, McGill University Health Center, Montreal, Quebec, Canada; Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | - Thomas Kitzler
- Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | - Dany Matar
- McKinsey & Company, Washington, District of Columbia; and
| | - Andrey V Cybulsky
- Department of Medicine, McGill University and McGill University Health Center, Montreal, Quebec, Canada
| | - Nada Alachkar
- Division of Nephrology, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Elena Torban
- Department of Medicine, McGill University and McGill University Health Center, Montreal, Quebec, Canada;
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Full-length soluble urokinase plasminogen activator receptor down-modulates nephrin expression in podocytes. Sci Rep 2015; 5:13647. [PMID: 26380915 PMCID: PMC4585377 DOI: 10.1038/srep13647] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 08/03/2015] [Indexed: 12/25/2022] Open
Abstract
Increased plasma level of soluble urokinase-type plasminogen activator receptor (suPAR) was associated recently with focal segmental glomerulosclerosis (FSGS). In addition, different clinical studies observed increased concentration of suPAR in various glomerular diseases and in other human pathologies with nephrotic syndromes such as HIV and Hantavirus infection, diabetes and cardiovascular disorders. Here, we show that suPAR induces nephrin down-modulation in human podocytes. This phenomenon is mediated only by full-length suPAR, is time-and dose-dependent and is associated with the suppression of Wilms’ tumor 1 (WT-1) transcription factor expression. Moreover, an antagonist of αvβ3 integrin RGDfv blocked suPAR-induced suppression of nephrin. These in vitro data were confirmed in an in vivo uPAR knock out Plaur−/− mice model by demonstrating that the infusion of suPAR inhibits expression of nephrin and WT-1 in podocytes and induces proteinuria. This study unveiled that interaction of full-length suPAR with αvβ3 integrin expressed on podocytes results in down-modulation of nephrin that may affect kidney functionality in different human pathologies characterized by increased concentration of suPAR.
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32
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Delville M, Sigdel TK, Wei C, Li J, Hsieh SC, Fornoni A, Burke GW, Bruneval P, Naesens M, Jackson A, Alachkar N, Canaud G, Legendre C, Anglicheau D, Reiser J, Sarwal MM. A circulating antibody panel for pretransplant prediction of FSGS recurrence after kidney transplantation. Sci Transl Med 2015; 6:256ra136. [PMID: 25273097 DOI: 10.1126/scitranslmed.3008538] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Recurrence of focal segmental glomerulosclerosis (rFSGS) after kidney transplantation is a cause of accelerated graft loss. To evaluate pathogenic antibodies (Abs) in rFSGS, we processed 141 serum samples from 64 patients with and without primary rFSGS and 34 non-FSGS control patients transplanted at four hospitals. We screened about 9000 antigens in pretransplant sera and selected 10 Abs targeting glomerular antigens for enzyme-linked immunosorbent assay (ELISA) validation. A panel of seven Abs (CD40, PTPRO, CGB5, FAS, P2RY11, SNRPB2, and APOL2) could predict posttransplant FSGS recurrence with 92% accuracy. Pretransplant elevation of anti-CD40 Ab alone had the best correlation (78% accuracy) with rFSGS risk after transplantation. Epitope mapping of CD40 with customized peptide arrays and rFSGS sera demonstrated altered immunogenicity of the extracellular CD40 domain in rFSGS. Immunohistochemistry of CD40 demonstrated a differential expression in FSGS compared to non-FSGS controls. Anti-CD40 Abs purified from rFSGS patients were particularly pathogenic in human podocyte cultures. Injection of anti-CD40/rFSGS Ab enhanced suPAR (soluble urokinase receptor)-mediated proteinuria in wild-type mice, yet no sensitizing effect was noted in mice deficient in CD40 or in wild-type mice that received blocking Ab to CD40. In conclusion, a panel of seven Abs can help identify primary FSGS patients at high risk of recurrence before transplantation. Intrarenal CD40 (and possibly other specific glomerular antigens) is an important contributor to FSGS disease pathogenesis. Human trials of anti-CD40 therapies are warranted to evaluate their efficacy for preventing rFSGS and improving graft survival.
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Affiliation(s)
- Marianne Delville
- Department of Kidney Transplantation, Necker Hospital, Assistance Publique-Hôpitaux de Paris, Université Paris Descartes Sorbonne Paris Cité, INSERM U1171, Réseau Thématique de Recherche et de Soins Centaure, Labex Transplantex, 75015 Paris, France
| | - Tara K Sigdel
- Division of Transplant Surgery, University of California San Francisco, San Francisco, CA 94143, USA
| | - Changli Wei
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Jing Li
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Szu-Chuan Hsieh
- Division of Transplant Surgery, University of California San Francisco, San Francisco, CA 94143, USA
| | - Alessia Fornoni
- Peggy and Harold Katz Family Drug Discovery Center, Division of Nephrology and Hypertension, University of Miami School of Medicine, Miami, FL 33146, USA
| | - George W Burke
- Division of Transplant Surgery, University of Miami School of Medicine, Miami, FL 33146, USA
| | - Patrick Bruneval
- Department of Pathology, Hôpital Européen Georges Pompidou, 20 rue Leblanc, 75015 Paris, France
| | - Maarten Naesens
- Nephrology and Renal Transplantation, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Annette Jackson
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Nada Alachkar
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Guillaume Canaud
- Department of Kidney Transplantation, Necker Hospital, Assistance Publique-Hôpitaux de Paris, Université Paris Descartes Sorbonne Paris Cité, INSERM U1171, Réseau Thématique de Recherche et de Soins Centaure, Labex Transplantex, 75015 Paris, France
| | - Christophe Legendre
- Department of Kidney Transplantation, Necker Hospital, Assistance Publique-Hôpitaux de Paris, Université Paris Descartes Sorbonne Paris Cité, INSERM U1171, Réseau Thématique de Recherche et de Soins Centaure, Labex Transplantex, 75015 Paris, France
| | - Dany Anglicheau
- Department of Kidney Transplantation, Necker Hospital, Assistance Publique-Hôpitaux de Paris, Université Paris Descartes Sorbonne Paris Cité, INSERM U1171, Réseau Thématique de Recherche et de Soins Centaure, Labex Transplantex, 75015 Paris, France
| | - Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA.
| | - Minnie M Sarwal
- Division of Transplant Surgery, University of California San Francisco, San Francisco, CA 94143, USA.
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33
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Mathieson PW. The podocyte cytoskeleton in health and in disease. Clin Kidney J 2015; 5:498-501. [PMID: 26069792 PMCID: PMC4400570 DOI: 10.1093/ckj/sfs153] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 09/27/2012] [Indexed: 11/18/2022] Open
Abstract
The podocyte is a key cell in the selective filtering action of the glomerular capillary wall. Podocyte injury is of pathogenetic and prognostic significance in human glomerular disease; podocyte repair and regeneration are important therapeutic targets. In particular, podocyte function is dependent on the cells' actin cytoskeleton: this maintains their complex structure. Alterations in the actin cytoskeleton arise from a variety of genetic and acquired causes. Therapeutic agents that are beneficial in proteinuric disease may act at least partly by restoring the cell shape via effects on the actin cytoskeleton. Recent studies of podocytes in vivo and in vitro are described, highlighting clinically relevant observations and those that help us understand the ways in which we may harness nature's own mechanisms to repair and/or renew these specialized glomerular cells, with a particular focus on their actin cytoskeleton. Drugs that have beneficial effects on podocytes can improve our ability to treat important renal diseases including diabetic nephropathy. Currently available agents can be applied in this way and the rapid progress in the study of podocytes is highlighting new therapeutic targets that can bring even more specificity.
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Affiliation(s)
- Peter W Mathieson
- Faculty of Medicine & Dentistry , University of Bristol, North Bristol NHS Trust , Bristol , UK ; Academic Renal Unit , Southmead Hospital , Bristol , UK
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34
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Abkhezr M, Kim EY, Roshanravan H, Nikolos F, Thomas C, Hagmann H, Benzing T, Dryer SE. Pleiotropic signaling evoked by tumor necrosis factor in podocytes. Am J Physiol Renal Physiol 2015; 309:F98-108. [PMID: 26017975 DOI: 10.1152/ajprenal.00146.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 05/18/2015] [Indexed: 02/05/2023] Open
Abstract
TNF has been implicated in glomerular diseases, but its actions on podocytes are not well understood. Endogenous TNF expression is markedly increased in mouse podocytes exposed to sera from patients with recurrent focal segmental glomerulosclerosis, and TNF is able to increase its own expression in these cells. Exposure of podocytes to TNF increased phosphorylation of NF-κB p65-RelA followed by increased tyrosine phosphorylation of STAT3. STAT3 activation was blocked by the NF-κB inhibitor JSH-23 and by the STAT3 inhibitor stattic, whereas TNF-evoked NF-κB activation was not affected by stattic. TNF treatment increased nuclear accumulation of nuclear factor of activated T cells (NFAT)c1 in podocytes, a process that occurred downstream of STAT3 activation. TNF also increased expression of cyclin D1 but had no effect on cyclin-dependent kinase 4, p27(kip), or podocin. Despite its effects on cyclin D1, TNF treatment for up to 72 h did not cause podocytes to reenter the cell cycle. TNF increased total expression of transient receptor potential (TRP)C6 channels through a pathway dependent on NFATc1 and increased the steady-state expression of TRPC6 subunits on the podocyte cell surface. TNF effects on TRPC6 trafficking required ROS. Consistent with this, La(3+)-sensitive cationic currents activated by a diacylglycerol analog were increased in TNF-treated cells. The effects of TNF on NFATc1 and TRPC6 expression were blocked by cyclosporine A but were not blocked by the pan-TRP inhibitor SKF-96365. TNF therefore influences multiple pathways previously implicated in podocyte pathophysiology and is likely to sensitize these cells to other insults.
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Affiliation(s)
- Mousa Abkhezr
- Department of Biology and Biochemistry, University of Houston, Houston, Texas
| | - Eun Young Kim
- Department of Biology and Biochemistry, University of Houston, Houston, Texas
| | - Hila Roshanravan
- Department of Biology and Biochemistry, University of Houston, Houston, Texas
| | - Fotis Nikolos
- Department of Biology and Biochemistry, University of Houston, Houston, Texas; Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, Texas; and
| | - Christoforos Thomas
- Department of Biology and Biochemistry, University of Houston, Houston, Texas; Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, Texas; and
| | - Henning Hagmann
- Department of Internal Medicine, University of Cologne, Cologne, Germany
| | - Thomas Benzing
- Department of Internal Medicine, University of Cologne, Cologne, Germany
| | - Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, Texas; Division of Nephrology, Baylor College of Medicine, Houston, Texas
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35
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Maas RJ, Deegens JK, Wetzels JF. Permeability factors in idiopathic nephrotic syndrome: historical perspectives and lessons for the future. Nephrol Dial Transplant 2015; 29:2207-16. [PMID: 25416821 DOI: 10.1093/ndt/gfu355] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The term idiopathic nephrotic syndrome (iNS) traditionally covers minimal change disease and primary focal segmental glomerulosclerosis (FSGS), now thought to be separate disease entities. Clinical and experimental evidence suggest that circulating permeability factors are involved in their pathogenesis. In the past four decades, many investigators have searched for the responsible factors, thus far with little success. The recent report of the soluble urokinase plasminogen activator receptor as a causative factor in FSGS has received much attention, but again the initially promising findings were not confirmed. We describe the history of the search for permeability factors, discuss the pitfalls that are likely responsible for the lack of success and propose criteria that should be used in future studies when evaluating candidate permeability factors.
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Affiliation(s)
- Rutger J Maas
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen K Deegens
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jack F Wetzels
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
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36
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Sinha A, Menon S, Bagga A. Nephrotic Syndrome: State of the Art. CURRENT PEDIATRICS REPORTS 2015. [DOI: 10.1007/s40124-014-0066-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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37
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Saleem MA. One hundred ways to kill a podocyte. Nephrol Dial Transplant 2015; 30:1266-71. [PMID: 25637640 DOI: 10.1093/ndt/gfu363] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 10/27/2014] [Indexed: 12/30/2022] Open
Abstract
The podocyte is a highly specialized cell, forming within the developing glomerulus from a mesenchymal origin, acquiring some but not complete features of an epithelial cell as it matures. Once mature, this cell has the potential to receive signals from several different directions and sits within a dynamic microenvironment. By taking an overview of many lines of evidence, it is clear that we already know many signals that are tightly controlled in keeping the podocyte healthy. For example, vascular endothelial growth factor, insulin and integrins are all known to have bidirectional effects on podocyte functionality, depending on whether there is too much or too little. It is of little surprise therefore that disrupting this delicate balance can result in a dramatic loss of function, and manifestation of glomerular disease originating from many different primary insults. The cues directing podocyte phenotype and functionality for the purpose of this review will be divided into four main sources: (i) genetic, (ii) paracrine signals from endothelial and mesangial cells, (iii) direct contact signals to/from the glomerular basement membrane and (iv) signals from circulating plasma. Of course there are other influences, which we still know little about, such as flow and shear stresses, signals from the urinary space that should all be considered in the overall healthy environment.
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Affiliation(s)
- Moin A Saleem
- Bristol Children's Hospital, University of Bristol, Bristol, UK
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38
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Holmberg C, Jalanko H. Congenital nephrotic syndrome and recurrence of proteinuria after renal transplantation. Pediatr Nephrol 2014; 29:2309-17. [PMID: 24682440 PMCID: PMC4212136 DOI: 10.1007/s00467-014-2781-z] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 01/27/2014] [Accepted: 01/31/2014] [Indexed: 01/16/2023]
Abstract
Renal transplantation (RTx) is the only curative treatment for most cases of congenital and infantile nephrotic syndrome (NS) caused by genetic defects in glomerular podocyte proteins. The outcome of RTx in these children is usually excellent, with no recurrence of nephrotic syndrome. A subgroup of patients with the Finnish type of congenital nephrosis (CNF), shows, however, a clear risk for post-RTx proteinuria. Most of these patients have a homozygous truncating mutation (Fin-major mutation) in the nephrin gene (NPHS1), leading to total absence of the major podocyte protein, nephrin. After RTx, these patients develop anti-nephrin antibodies resulting in nephrotic range proteinuria. Plasma exchange combined with cyclophosphamide and anti-CD20 antibodies has proved to be successful therapy for these episodes. NS recurrence has also occurred in a few patients with mutations in the podocin gene (NPHS2). No anti-podocin antibodies have been detectable, and the pathophysiology of the recurrence remains open. While most of these episodes have resolved, the optimal therapy remains to be determined.
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Affiliation(s)
- Christer Holmberg
- Children's Hospital, University of Helsinki and Helsinki University Central Hospital, PO Box 281, Helsinki, 00290, Finland,
| | - Hannu Jalanko
- Children’s Hospital, University of Helsinki and Helsinki University Central Hospital, PO Box 281, Helsinki, 00290 Finland
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39
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Maas RJH, Deegens JKJ, Wetzels JFM. Serum suPAR in patients with FSGS: trash or treasure? Pediatr Nephrol 2013; 28:1041-8. [PMID: 23515666 DOI: 10.1007/s00467-013-2452-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 01/20/2013] [Accepted: 02/26/2013] [Indexed: 12/12/2022]
Abstract
The urokinase-type plasminogen activator receptor (uPAR) has important functions in cell migration. uPAR can be shed from the cell membrane resulting in soluble uPAR (suPAR). Further cleavage gives rise to shorter fragments with largely unknown functions. Recent studies have demonstrated that both overexpression of uPAR on podocytes and the administration of suPAR cause proteinuria in mice. The common pathogenic mechanism involves the activation of podocyte β3-integrin. Increased activation of β3-integrin is also observed in patients with focal and segmental glomerulosclerosis (FSGS). These observations form the basis for the hypothesis that suPAR may be the circulating factor causing FSGS. A recent study fosters this idea by demonstrating increased suPAR levels in the serum of patients with FSGS and reporting an association with recurrence after transplantation and response to plasmapheresis. However, this study was heavily biased, and subsequent studies have given conflicting results. Although the experimental work is very suggestive, at present there is no proof that any known human suPAR fragment causes FSGS in humans. We therefore suggest that the measurement of suPAR using currently available assays has absolutely no value at the present time in decision-making in routine clinical practice.
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Affiliation(s)
- Rutger J H Maas
- Department of Nephrology 464, Radboud University Nijmegen Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
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40
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Demirhan E, Eskut NP, Zorlu Y, Cukurova I, Tuna G, Kirkali FG. Blood levels of TNF-α, IL-10, and IL-12 in idiopathic sudden sensorineural hearing loss. Laryngoscope 2013; 123:1778-81. [PMID: 23382065 DOI: 10.1002/lary.23907] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2012] [Indexed: 12/20/2022]
Abstract
OBJECTIVES/HYPOTHESIS To investigate the blood levels of TNF-α, IL-10, and IL-12 in the idiopathic sudden sensorineural hearing loss patients, and the change of these cytokine levels after treatment. STUDY DESIGN Prospective clinical trial. METHODS Twenty-three patients with idiopathic sudden sensorineural hearing loss and 20 healthy people were selected as study and control groups. Blood samples for TNF-α, IL-10, and IL-12 were taken before treatment and 6 weeks after treatment. The study group was given combined treatment including dexamethasone, heparin, pentoxifyline, vitamin B1, and B6 for 10 days, and was divided into two groups: treatment responders and treatment nonresponders. The treatment responders group was also divided into three groups according to most accepted criteria for improvement in the literature. Audiograms were taken before treatment and 6 weeks after treatment to determine the response to the treatment. RESULTS There was no significant difference between pre- and posttreatment values of IL-10 and IL-12 in all study groups (P > 0.05). There was also no significant difference between pre- and posttreatment values of TNF-α in treatment responders (P > 0.05). Treatment nonresponders had more elevated posttreatment values of TNF-α than pretreatment values (P < 0.05). CONCLUSION IL-10 and IL-12 may not play a critical role in idiopathic sudden sensorineural hearing loss. But our data supports the role of TNF-α in the pathophysiology of idiopathic sudden sensorineural hearing loss, and TNF-α receptor blockers may have benefits in these patients.
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Affiliation(s)
- Erhan Demirhan
- Department of Otorhinolaryngology, Eregli State Hospital, Zonguldak, Turkey.
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Sachs N, Sonnenberg A. Cell-matrix adhesion of podocytes in physiology and disease. Nat Rev Nephrol 2013; 9:200-10. [PMID: 23338211 DOI: 10.1038/nrneph.2012.291] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cell-matrix adhesion is crucial for maintaining the mechanical integrity of epithelial tissues. Podocytes--a key component of the glomerular filtration barrier--are exposed to permanent transcapillary filtration pressure and must therefore adhere tightly to the underlying glomerular basement membrane (GBM). The major cell-matrix adhesion receptor in podocytes is the integrin α3β1, which connects laminin 521 in the GBM through various adaptor proteins to the intracellular actin cytoskeleton. Other cell-matrix adhesion receptors expressed by podocytes include the integrins α2β1 and αvβ3, α-dystroglycan, syndecan-4 and type XVII collagen. Mutations in genes encoding any of the components critical for podocyte adhesion cause glomerular disease. This Review highlights recent advances in our understanding of the cell biology and genetics of podocyte adhesion with special emphasis on glomerular disease.
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Affiliation(s)
- Norman Sachs
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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The phenomenon of focal segmental glomerulosclerosis post-transplantation--a one-hit wonder? Pediatr Nephrol 2012; 27:2163-6. [PMID: 22806560 DOI: 10.1007/s00467-012-2218-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 05/07/2012] [Accepted: 05/08/2012] [Indexed: 10/28/2022]
Abstract
Steroid resistant nephrotic syndrome (SRNS), otherwise termed focal segmental glomerulosclerosis (FSGS) is one of the most difficult conditions to manage for the nephrologist, particularly when the disease recurs post-transplantation. It is also fascinating from the biological perspective, as the non-genetic form appears highly likely to be caused by a disorder of circulating plasma, leading to the search for the elusive 'plasma factor' over several decades of research. Many hypotheses have been proposed and tested, and to date none have yet passed the test of clinical utility. The search appears to be narrowing, aided by landmark discoveries in the molecular properties of the glomerular filtration barrier, and improved experimental tools. Therapeutically we are also more able to target specific molecules, for example by monoclonal antibody treatments. In this context, the report of the effects of TNF-α on podocytes is instructive. This tells us that this cytokine could have directly deleterious effects on podocytes in vivo, and that this effect can be targeted clinically, potentially halting or reversing the disease process. As with all thought provoking research, this raises several interesting questions. Is TNF-α the elusive 'factor' or is it one of several? Is it directly affecting the glomerular filtration barrier, or modulating the immune response? And could this technique be used as a cell based assay for disease activity? This report adds to the growing list of candidates that need to be tested in a wider population of well phenotyped patients with SRNS. [corrected].
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