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Erichsen L, Thimm C, Bohndorf M, Rahman MS, Wruck W, Adjaye J. Activation of the Renin–Angiotensin System Disrupts the Cytoskeletal Architecture of Human Urine-Derived Podocytes. Cells 2022; 11:cells11071095. [PMID: 35406662 PMCID: PMC8997628 DOI: 10.3390/cells11071095] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/10/2022] [Accepted: 03/21/2022] [Indexed: 01/27/2023] Open
Abstract
High blood pressure is one of the major public health problems that causes severe disorders in several tissues including the human kidney. One of the most important signaling pathways associated with the regulation of blood pressure is the renin–angiotensin system (RAS), with its main mediator angiotensin II (ANGII). Elevated levels of circulating and intracellular ANGII and aldosterone lead to pro-fibrotic, -inflammatory, and -hypertrophic milieu that causes remodeling and dysfunction in cardiovascular and renal tissues. Furthermore, ANGII has been recognized as a major risk factor for the induction of apoptosis in podocytes, ultimately leading to chronic kidney disease (CKD). In the past, disease modeling of kidney-associated diseases was extremely difficult, as the derivation of kidney originated cells is very challenging. Here we describe a differentiation protocol for reproducible differentiation of sine oculis homeobox homolog 2 (SIX2)-positive urine-derived renal progenitor cells (UdRPCs) into podocytes bearing typical cellular processes. The UdRPCs-derived podocytes show the activation of the renin–angiotensin system by being responsive to ANGII stimulation. Our data reveal the ANGII-dependent downregulation of nephrin (NPHS1) and synaptopodin (SYNPO), resulting in the disruption of the podocyte cytoskeletal architecture, as shown by immunofluorescence-based detection of α-Actinin. Furthermore, we show that the cytoskeletal disruption is mainly mediated through angiotensin II receptor type 1 (AGTR1) signaling and can be rescued by AGTR1 inhibition with the selective, competitive angiotensin II receptor type 1 antagonist, losartan. In the present manuscript we confirm and propose UdRPCs differentiated to podocytes as a unique cell type useful for studying nephrogenesis and associated diseases. Furthermore, the responsiveness of UdRPCs-derived podocytes to ANGII implies potential applications in nephrotoxicity studies and drug screening.
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CX3CR1 at V249M and T280M Gene Polymorphism and Its Potential Risk for End-Stage Renal Diseases in Egyptian Patients. Int J Nephrol 2021; 2021:6634365. [PMID: 33986961 PMCID: PMC8093072 DOI: 10.1155/2021/6634365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 04/07/2021] [Accepted: 04/12/2021] [Indexed: 11/17/2022] Open
Abstract
CX3CL1-CX3CR1 pathway may be one of the future treatment targets to delay the progression of end-stage renal diseases. This study aimed to evaluate the CX3CR gene polymorphism in Egyptian patients with ESRD and its relation to fractalkine blood level. The study included 100 patients with ESRD on dialysis, 61 males and 39 females with mean age 51.02 ± 7.8 years. The V2491 genotype revealed a significant increase in the frequency of GG genotype in healthy control (83%) compared to patients [69%] with a significant increase in GA in patients [30%] compared to control subjects [15%], P = 0.03. T280M study showed a statistically significant prevalence of TT genotype in healthy control subjects [86%-OR 95% CI 1.7] compared to patients [70%] with a significant increase in the prevalence of TA in patients [29%] compared to control subjects [13%], P = 0.01. There was a significant increase in fractalkine levels in genotypes GA + AA [503.04±224.1] pg/ml compared to genotype GG [423.6 210.3], P = 0.03. Moreover, there was a significant increase in the blood level of fractalkine in genotype TA + AA [498.8 219.6] compared to genotype TT [426.8±212.8], P = 0.05. In conclusion, our study showed that both V2491-GA genotype and T280M-TA are associated with potential risk for end-stage renal disease in Egyptian patients.
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You Y, Qin Y, Lin X, Yang F, Wang J, Yuan F, Sooranna SR, Pinhu L. Upregulated fractalkine levels in Chinese patients with lupus nephritis. Cytokine 2018; 104:23-28. [PMID: 29414322 DOI: 10.1016/j.cyto.2018.01.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 01/27/2018] [Accepted: 01/31/2018] [Indexed: 01/22/2023]
Abstract
OBJECTIVE To investigate the expression levels of fractalkine (FKN) mRNA in peripheral blood mononuclear cells (PBMCs) and FKN protein in serum of patients with lupus nephritis (LN) from China, and to evaluate the associations between the expression of FKN and systemic lupus erythematosus disease activity index 2000 (SLEDAI-2 K), anti-double-stranded DNA and complement proteins in LN patients. METHODS Real-time quantitative polymerase chain reaction and enzyme-linked immunosorbent assay were used to detect the expression levels of FKN mRNA in PBMCs and FKN protein in serum separately from 105 patients with LN and 52 healthy controls. RESULTS Serum level and mRNA level of FKN were significantly increased in LN patients when compared to controls (P < 0.001). Higher FKN levels were found in active LN patients and LN patients with renal damage when compared with inactive LN patients and LN patients without renal damage (P < 0.001). Higher serum FKN levels were detected in inactive LN patients in comparison with healthy controls (Z = -7.165, P < 0.001). The FKN expression levels were positively correlated with SLEDAI-2 K, and was associated with the presence of autoantibodies and negatively correlated with complement proteins C3 and C4 in LN patients. CONCLUSIONS The results suggest that upregulation of FKN is associated with the pathogenesis and activity of LN in Chinese patients.
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Affiliation(s)
- Yanwu You
- Department of Nephrology, Affiliated Hospital of Youjiang Medical University for Nationalities, No. 18 Zhongshan Road, Baise 533000, Guangxi Zhuang Autonomous Region, China.
| | - Yueqiu Qin
- Department of Gastroenterology, Affiliated Hospital of Youjiang Medical University for Nationalities, No. 18 Zhongshan Road, Baise 533000, Guangxi Zhuang Autonomous Region, China.
| | - Xu Lin
- Department of Nephrology, Affiliated Hospital of Youjiang Medical University for Nationalities, No. 18 Zhongshan Road, Baise 533000, Guangxi Zhuang Autonomous Region, China.
| | - Fafen Yang
- Department of Nephrology, Affiliated Hospital of Youjiang Medical University for Nationalities, No. 18 Zhongshan Road, Baise 533000, Guangxi Zhuang Autonomous Region, China.
| | - Junjie Wang
- Department of Nephrology, Affiliated Hospital of Youjiang Medical University for Nationalities, No. 18 Zhongshan Road, Baise 533000, Guangxi Zhuang Autonomous Region, China.
| | - Fang Yuan
- Department of Nephrology, Affiliated Hospital of Youjiang Medical University for Nationalities, No. 18 Zhongshan Road, Baise 533000, Guangxi Zhuang Autonomous Region, China.
| | - Suren R Sooranna
- Department of Surgery and Cancer, Imperial College London, Chelsea and Westminster Hospital, 369, Fulham Road, London SW10 9NH, UK.
| | - Liao Pinhu
- Department of Intensive Care Medicine, Affiliated Hospital of Youjiang Medical University for Nationalities, No. 18 Zhongshan Road, Baise 533000, Guangxi Zhuang Autonomous Region, China.
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Effects of ROS-relative NF-κB signaling on high glucose-induced TLR4 and MCP-1 expression in podocyte injury. Mol Immunol 2015; 68:261-71. [PMID: 26364141 DOI: 10.1016/j.molimm.2015.09.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 08/31/2015] [Accepted: 09/01/2015] [Indexed: 02/02/2023]
Abstract
High glucose (HG) induced inflammation is central to progression in diabetic nephropathy (DN). Recent studies have suggested that nuclear factor-kappa B (NF-κB) signaling activation is associated with DN, and podocyte damage may be involved in orchestrating these effects. Therefore, the aim of this study was to investigate the effects of NF-κB signaling on podocytes under HG conditions. The effects of HG and NF-κB signaling on podocytes were assessed by CCK-8 assay, cellular NF-κB translocation assay, measurement of reactive oxygen species (ROS) and Western blot analysis. We found that HG reduced cell viability, activated NF-κB signaling and up-regulated toll-like receptor 4 (TLR4) and monocyte chemoattractant protein-1 (MCP-1). In these cells, NF-κB inhibition with ammonium pyrrolidinethiocarbamate (PDTC) resulted in effectively constraining TLR4 and MCP-1 up-regulation, indicating that protective effects associated with the inhibition of NF-κB were linked to TLR4 and MCP-1 down-regulation in podocytes. Furthermore, HG significantly increased the production of intracellular ROS. Pretreatment with N-acetyl-l-cysteine (NAC) significantly inhibited intracellular ROS generation and increased cell viability, accompanied by a significant NF-κB inhibition and suppression of TLR4 and inflammatory cytokine MCP-1 expression. Collectively, our novel data suggest that HG induces the over-experssion of TLR-4 and MCP-1 through a NF-κB-dependent signaling. NF-κB-mediated increased inflammation is possibly via ROS and contributes to the cell injury. These results may provide potential therapeutic target for diabetic nephropathy in the future.
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You Y, Qin Y, Lin X, Yang F, Li J, Sooranna SR, Pinhu L. Methylprednisolone attenuates lipopolysaccharide-induced Fractalkine expression in kidney of Lupus-prone MRL/lpr mice through the NF-kappaB pathway. BMC Nephrol 2015; 16:148. [PMID: 26310926 PMCID: PMC4551515 DOI: 10.1186/s12882-015-0145-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 03/05/2015] [Accepted: 08/20/2015] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Fractalkine (FKN) is involved in the occurrence and development of human lupus nephritis. It is known to be upregulated by lipopolysaccharide (LPS) as a stimulus in vivo. MRL/lpr mice have been used as an in vivo model to study lupus nephritis. Methylprednisolone (MP) is used widely in the clinical treatment of progressive glomerular diseases such as lupus nephritis. The aim of this study is to explore the mechanism of LPS induced FKN expression and to determine whether other molecular mechanisms contribute to the signaling pathway of MP action in MRL/lpr mice. METHODS Forty-eight female MRL/lpr mice at 12 weeks of age were randomly distributed into six groups. Each group received various treatments for 8 weeks by receiving twice weekly intraperitoneal injections of (1) MP (MP-treated mice), of (2) SC-514 (SC-514-induced mice), of (3) normal saline and a single injection of LPS (LPS-induced mice), of (4) MP and a single injection of LPS (LPS + MP mice), of (5) SC-514 and a single injection of LPS (LPS + SC mice) and of (6) normal saline (control mice). One-way ANOVA was used for data analysis and P value <0.05 was considered statistically significantly. RESULTS The expression of FKN and NF-kappaB p65 mRNA was detected by qPCR. The expression of FKN protein and the activation of NF-kappaB p65 were detected by immunohistochemistry and western blots respectively. The expression of FKN in the kidney of LPS induced mice was significantly increased and this was mediated by increased expression of NF-κB p65 and an increase in NF-kappaB phospho-p65. MP reduced proteinuria and ameliorated the renal damage in MRL/lpr mice. MP as well as the NF-kappaB inhibitor, SC-514, inhibited the LPS-induced increase of expression of FKN and the activation of NF-kappaB. CONCLUSIONS The results indicate that MP attenuates LPS-induced FKN expression in kidney of MRL/lpr mice through the NF-kappaB pathway.
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Affiliation(s)
- Yanwu You
- Department of Nephrology, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, 533000, Guangxi Zhuang Autonomous Region, China.
| | - Yueqiu Qin
- Department of Gastroenterology, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, 533000, Guangxi Zhuang Autonomous Region, China.
| | - Xu Lin
- Department of Nephrology, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, 533000, Guangxi Zhuang Autonomous Region, China.
| | - Fafen Yang
- Department of Nephrology, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, 533000, Guangxi Zhuang Autonomous Region, China.
| | - Jun Li
- Department of Intensive Care Medicine, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, 533000, Guangxi Zhuang Autonomous Region, China.
| | - Suren R Sooranna
- Department of Surgery and Cancer, Imperial College London, Chelsea and Westminster Hospital, London, SW10 9NH, UK.
| | - Liao Pinhu
- Department of Intensive Care Medicine, Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, 533000, Guangxi Zhuang Autonomous Region, China.
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Shah R, Matthews GJ, Shah RY, McLaughlin C, Chen J, Wolman M, Master SR, Chai B, Xie D, Rader DJ, Raj DS, Mehta NN, Budoff M, Fischer MJ, Go AS, Townsend RR, He J, Kusek JW, Feldman HI, Foulkes AS, Reilly MP. Serum Fractalkine (CX3CL1) and Cardiovascular Outcomes and Diabetes: Findings From the Chronic Renal Insufficiency Cohort (CRIC) Study. Am J Kidney Dis 2015; 66:266-73. [PMID: 25795074 DOI: 10.1053/j.ajkd.2015.01.021] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 01/25/2015] [Indexed: 11/11/2022]
Abstract
BACKGROUND Cardiometabolic disease is a major cause of morbidity and mortality in persons with chronic kidney disease (CKD). Fractalkine (CX3CL1) is a potential mediator of both atherosclerosis and metabolic disease. Studies of the relationship of CX3CL1 with risk of cardiovascular disease (CVD) events and metabolic traits are lacking, particularly in the high-risk setting of CKD. STUDY DESIGN Cross-sectional and longitudinal observational analysis. SETTING & PARTICIPANTS Adults with CKD from 7 US sites participating in the Chronic Renal Insufficiency Cohort (CRIC) Study. PREDICTOR Quartiles of plasma CX3CL1 levels at baseline. OUTCOMES Baseline estimated glomerular filtration rate from a creatinine and cystatin C-based equation, prevalent and incident CVD, diabetes, metabolic syndrome and its criteria, homeostatic model assessment of insulin resistance, hemoglobin A1c level, myocardial infarction, all-cause mortality, and the composite outcome of myocardial infarction/all-cause mortality. RESULTS Among 3,687 participants, baseline CX3CL1 levels were associated positively with several CVD risk factors and metabolic traits, lower estimated glomerular filtration rate, and higher levels of inflammatory cytokines, as well as prevalent CVD (OR, 1.09; 95% CI, 1.01-1.19; P=0.03). Higher CX3CL1 level also was associated with prevalent diabetes (OR, 1.26; 95% CI, 1.16-1.38; P<0.001) in adjusted models. During a mean follow-up of 6 years, there were 352 deaths, 176 myocardial infarctions, and 484 composite outcomes. In fully adjusted models, 1-SD higher CX3CL1 level increased the hazard for all-cause mortality (1.11; 95% CI, 1.00-1.22; P=0.02) and the composite outcome (1.09; 95% CI, 1.00-1.19; P=0.04). LIMITATIONS Study design did not allow evaluation of changes over time, correlation with progression of phenotypes, or determination of causality of effect. CONCLUSIONS Circulating CX3CL1 level may contribute to both atherosclerotic CVD and diabetes in a CKD cohort. Further studies are required to establish mechanisms through which CX3CL1 affects the pathogenesis of atherosclerosis and diabetes.
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Affiliation(s)
- Rachana Shah
- Division of Endocrinology and Diabetes, Children's Hospital of Philadelphia, Philadelphia, PA.
| | - Gregory J Matthews
- School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA
| | - Rhia Y Shah
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Catherine McLaughlin
- Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
| | - Jing Chen
- Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA
| | - Melanie Wolman
- Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Stephen R Master
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Boyang Chai
- Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Dawei Xie
- Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Daniel J Rader
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | | | - Nehal N Mehta
- National Heart, Lung and Blood Institute, Bethesda, MD
| | | | - Michael J Fischer
- Medicine, Jesse Brown VA Medical Center and University of Hospital and Health Sciences System, Chicago; Center of Innovation for Complex Chronic Healthcare, Edward Hines Jr VA Hospital, Hines, IL
| | - Alan S Go
- Division of Research, Kaiser Permanente of Northern California, Oakland, CA
| | - Raymond R Townsend
- Renal Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia PA
| | - Jiang He
- Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA
| | - John W Kusek
- National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD
| | - Harold I Feldman
- Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA; Renal Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia PA
| | - Andrea S Foulkes
- School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA
| | - Muredach P Reilly
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA.
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Wei M, Li Z, Yang Z. Crosstalk between protective autophagy and NF-κB signal in high glucose-induced podocytes. Mol Cell Biochem 2014; 394:261-73. [PMID: 24957786 DOI: 10.1007/s11010-014-2102-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 05/15/2014] [Indexed: 01/07/2023]
Abstract
Despite a great deal of recent studies focused on the pivotal role of autophagy in maintaining podocyte energy homeostasis, the mechanisms of autophagy in regulating transcriptional factors under high glucose (HG) condition are not fully understood. Here, we evaluated the effect of HG on nuclear factor-kappa B (NF-κB) signaling and autophagic process. The results showed that HG promoted autophagy in podocytes. Bafilomycin A1 (Baf A1) further enhanced this effect, but 3-methyadenine (3-MA) inhibited it. The proautophagic effects of HG manifested in the form of enhanced podocyte expression of light chain 3 (LC3)-II. In these cells, blockade of NF-κB signal by ammonium pyrrolidinethiocarbamate constrained in effectively reducing LC3-II up-regulation and increasing podocyte apoptosis. Furthermore, the autophagy inhibitors, such as Baf A1 and 3-MA, significantly enhanced HG-induced NF-κB activation and increased apoptosis. Thus, we conclude that the accumulation of autophagosomes results from enhancement of the autophagic flux, but not the blockage of autophagosome-lysosome fusion by HG. We also prove that HG-induced apoptosis, autophagy, and NF-κB signal are in a close crosstalk through a yet undetermined mechanism in podocytes.
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Affiliation(s)
- Miaomiao Wei
- College of Medicine, Tianjin Key Laboratory of Tumor Microenvironment and Neurovascular Regulation, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, 300071, China
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Sanchez-Niño MD, Poveda J, Sanz AB, Mezzano S, Carrasco S, Fernandez-Fernandez B, Burkly LC, Nair V, Kretzler M, Hodgin JB, Ruiz-Ortega M, Selgas R, Egido J, Ortiz A. Fn14 in podocytes and proteinuric kidney disease. Biochim Biophys Acta Mol Basis Dis 2013; 1832:2232-43. [PMID: 23999007 DOI: 10.1016/j.bbadis.2013.08.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 08/22/2013] [Accepted: 08/26/2013] [Indexed: 10/26/2022]
Abstract
Non-proliferative proteinuric diseases are the most common primary glomerular disorders causing end-stage renal disease. These disorders may associate low level glomerular inflammation and podocyte expression of inflammatory mediators. However, the factors regulating podocyte expression of inflammatory mediators in vivo in non-immune disorders are poorly understood. We have now explored the regulation and role of TWEAK receptor Fn14 in mediating glomerular inflammation in cultured podocytes and in experimental and human non-immune proteinuria. Transcriptomics disclosed Fn14 and MCP-1 mRNA upregulation in glomeruli from patients with focal segmental glomerulosclerosis, as well as a correlation between the expression of both transcripts. Increased glomerular Fn14 and MCP-1 mRNA was confirmed in a second focal segmental glomerulosclerosis cohort and was also observed in membranous nephropathy. In human non-proliferative proteinuric kidney diseases podocytes displayed Fn14 and MCP-1 expression and NFκB activation. Podocyte Fn14 was increased in murine protein overload-induced proteinuria. In Fn14 knock-out mice with protein overload-induced proteinuria, glomerular and periglomerular macrophage infiltrates were reduced, as were MCP-1 mRNA and podocyte MCP-1 staining and podocyte numbers preserved as compared to wild-type counterparts. Adenovirus-mediated overexpression of TWEAK increased periglomerular macrophage infiltration in mice without prior kidney injury. In cultured podocytes inflammatory cytokines increased Fn14 mRNA and protein levels. TWEAK activated NFκB and increased MCP-1 mRNA and protein, an effect prevented by the NFκB inhibitor parthenolide. In conclusion, Fn14 activation results in NFκB-mediated pro-inflammatory effects on podocytes that may be relevant for the pathogenesis of non-proliferative proteinuric kidney disease of non-immune origin.
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Abstract
The main function of chemokines is to guide inflammatory cells in their migration to sites of inflammation. During the last 2 decades, an expanding number of chemokines and their receptors have driven broad inquiry into how inflammatory cells are recruited in a variety of diseases. Although this review focuses on chemokines and their receptors in renal injury, proinflammatory IL-17, TGFβ, and TWEAK signaling pathways also play a critical role in their expression. Recent studies in transgenic mice as well as blockade of chemokine signaling by neutralizing ligands or receptor antagonists now allow direct interrogation of chemokine action. The emerging role of regulatory T cells and Th17 cells during renal injury also forges tight relationships between chemokines and T cell infiltration in the development of kidney disease. As chemokine receptor blockade inches toward clinical use, the field remains an attractive area with potential for unexpected opportunity in the future.
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Affiliation(s)
- Arthur C K Chung
- Department of Medicine and Therapeutics, and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China
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Abstract
The development of proliferative podocytopathies has been linked to ligation of tumor necrosis factor receptor 2 (TNFR2) expressed on the renal parenchyma; however, the TNFR2-positive cells within the kidney responsible for podocyte injury are unknown. We detected de novo expression of TNFR2 on podocytes before hyperplastic injury in crescentic glomerulonephritis of mice with nephrotoxic nephritis, and in collapsing glomerulopathy of Tg26(HIV/nl) mice, kd/kd mice, and human beings. We further found that serum levels of soluble TNF-α and TNFR2 correlated significantly with renal injury in Tg26(HIV/nl) mice. Thus, we asked whether ligand binding of TNFR2 on podocytes ex vivo precipitates the characteristic proliferative and pro-inflammatory diseased podocyte phenotypes. Soluble TNF-α activated NF-κB and dose-dependently induced podocyte proliferation, marked by the expression of the podocyte G(1) cyclin and NF-κB target gene, cyclin D1. Microarray gene and chemokine protein expression profiling showed a marked pro-inflammatory NF-κB signature, and activated podocytes secreting CCL2- and CCL5-induced macrophage migration in transwell assays. Neutralization of TNFR2 on podocytes with blocking antibodies abrogated NF-κB activation and the induction of cyclin D1 by TNF-α, and identified TNFR2 as the primary receptor that induced IκBα degradation, the initiating event in NF-κB activation. These results suggest that TNFR2 expressed on podocytes and its canonical NF-κB signaling may directly interpose the compound pathogenic responses by podocytes to TNF-α, in the absence of other TNFR2-positive renal cell types in proliferative podocytopathies.
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