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Lennon R, Byron A, Humphries JD, Randles MJ, Carisey A, Murphy S, Knight D, Brenchley PE, Zent R, Humphries MJ. Global analysis reveals the complexity of the human glomerular extracellular matrix. J Am Soc Nephrol 2014; 25:939-51. [PMID: 24436468 DOI: 10.1681/asn.2013030233] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The glomerulus contains unique cellular and extracellular matrix (ECM) components, which are required for intact barrier function. Studies of the cellular components have helped to build understanding of glomerular disease; however, the full composition and regulation of glomerular ECM remains poorly understood. We used mass spectrometry-based proteomics of enriched ECM extracts for a global analysis of human glomerular ECM in vivo and identified a tissue-specific proteome of 144 structural and regulatory ECM proteins. This catalog includes all previously identified glomerular components plus many new and abundant components. Relative protein quantification showed a dominance of collagen IV, collagen I, and laminin isoforms in the glomerular ECM together with abundant collagen VI and TINAGL1. Protein network analysis enabled the creation of a glomerular ECM interactome, which revealed a core of highly connected structural components. More than one half of the glomerular ECM proteome was validated using colocalization studies and data from the Human Protein Atlas. This study yields the greatest number of ECM proteins relative to previous investigations of whole glomerular extracts, highlighting the importance of sample enrichment. It also shows that the composition of glomerular ECM is far more complex than previously appreciated and suggests that many more ECM components may contribute to glomerular development and disease processes. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium with the dataset identifier PXD000456.
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Affiliation(s)
- Rachel Lennon
- Wellcome Trust Centre for Cell-Matrix Research and Faculty of Medical and Human Sciences, University of Manchester, Manchester, United Kingdom;
| | - Adam Byron
- Wellcome Trust Centre for Cell-Matrix Research and
| | | | - Michael J Randles
- Wellcome Trust Centre for Cell-Matrix Research and Faculty of Medical and Human Sciences, University of Manchester, Manchester, United Kingdom
| | - Alex Carisey
- Wellcome Trust Centre for Cell-Matrix Research and
| | - Stephanie Murphy
- Wellcome Trust Centre for Cell-Matrix Research and Faculty of Medical and Human Sciences, University of Manchester, Manchester, United Kingdom
| | - David Knight
- Biological Mass Spectrometry Core Facility, Faculty of Life Sciences, and
| | - Paul E Brenchley
- Faculty of Medical and Human Sciences, University of Manchester, Manchester, United Kingdom
| | - Roy Zent
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; and Department of Medicine, Veterans Affairs Hospital, Nashville, Tennessee
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Biphasic recruitment of microchimeric fetal mesenchymal cells in fibrosis following acute kidney injury. Kidney Int 2013; 85:600-10. [PMID: 24304884 DOI: 10.1038/ki.2013.459] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 09/03/2013] [Accepted: 09/05/2013] [Indexed: 12/19/2022]
Abstract
Fetal microchimeric cells (FMCs) enter the maternal circulation and persist in tissue for decades. They have capacity to home to injured maternal tissue and differentiate along that tissue's lineage. This raises the question of the origin(s) of cells transferred to the mother during pregnancy. FMCs with a mesenchymal phenotype have been documented in several studies, which makes mesenchymal stem cells an attractive explanation for their broad plasticity. Here we assessed the recruitment and mesenchymal lineage contribution of FMCs in response to acute kidney fibrosis induced by aristolochic acid injection. Serial in vivo bioluminescence imaging revealed a biphasic recruitment of active collagen-producing FMCs during the repair process of injured kidney in post-partum wild-type mothers that had delivered transgenic pups expressing luciferase under the collagen type I-promoter. The presence of FMCs long-term post injury (day 60) was associated with profibrotic molecules (TGF-β/CTGF), serum urea levels, and collagen deposition. Immunostaining confirmed FMCs at short term (day 15) using post-partum wild-type mothers that had delivered green fluorescent protein-positive pups and suggested a mainly hematopoietic phenotype. We conclude that there is biphasic recruitment to, and activity of, FMCs at the injury site. Moreover, we identified five types of FMC, implicating them all in the reparative process at different stages of induced renal interstitial fibrosis.
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Wu J, Zheng C, Fan Y, Zeng C, Chen Z, Qin W, Zhang C, Zhang W, Wang X, Zhu X, Zhang M, Zen K, Liu Z. Downregulation of microRNA-30 facilitates podocyte injury and is prevented by glucocorticoids. J Am Soc Nephrol 2013; 25:92-104. [PMID: 24029422 DOI: 10.1681/asn.2012111101] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
MicroRNAs (miRNAs) are essential for podocyte homeostasis, and the miR-30 family may be responsible for this action. However, the exact roles and clinical relevance of miR-30s remain unknown. In this study, we examined the expression of the miR-30 family in the podocytes of patients with FSGS and found that all members are downregulated. Treating cultured human podocytes with TGF-β, LPS, or puromycin aminonucleoside (PAN) also downregulated the miR-30 family. Podocyte cytoskeletal damage and apoptosis caused by treatment with TGF-β or PAN were ameliorated by exogenous miR-30 expression and aggravated by miR-30 knockdown. Moreover, we found that miR-30s exert their protective roles by direct inhibition of Notch1 and p53, which mediate podocyte injury. In rats, treatment with PAN substantially downregulated podocyte miR-30s and induced proteinuria and podocyte injury; however, transfer of exogenous miR-30a to podocytes of PAN-treated rats ameliorated proteinuria and podocyte injury and reduced Notch1 activation. Finally, we demonstrated that glucocorticoid treatment maintains miR-30 expression in cultured podocytes treated with TGF-β, LPS, or PAN and in the podocytes of PAN-treated rats. Glucocorticoid-sustained miR-30 expression associated with reduced Notch1 activation and alleviated podocyte damage. Taken together, these findings demonstrate that miR-30s protect podocytes by targeting Notch1 and p53 and that the loss of miR-30s facilitates podocyte injury. In addition, sustained miR-30 expression may be a novel mechanism underlying the therapeutic effectiveness of glucocorticoids in treating podocytopathy.
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Affiliation(s)
- Junnan Wu
- Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, Jiangsu, China
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Faherty N, O'Donovan H, Kavanagh D, Madden S, McKay GJ, Maxwell AP, Martin F, Godson C, Crean J. TGFβ and CCN2/CTGF mediate actin related gene expression by differential E2F1/CREB activation. BMC Genomics 2013; 14:525. [PMID: 23902294 PMCID: PMC3765338 DOI: 10.1186/1471-2164-14-525] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 07/16/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND CCN2/CTGF is an established effector of TGFβ driven responses in diabetic nephropathy. We have identified an interaction between CCN2 and TGFβ leading to altered phenotypic differentiation and inhibited cellular migration. Here we determine the gene expression profile associated with this phenotype and define a transcriptional basis for differential actin related gene expression and cytoskeletal function. RESULTS From a panel of genes regulated by TGFβ and CCN2, we used co-inertia analysis to identify and then experimentally verify a subset of transcription factors, E2F1 and CREB, that regulate an expression fingerprint implicated in altered actin dynamics and cell hypertrophy. Importantly, actin related genes containing E2F1 and CREB binding sites, stratified by expression profile within the dataset. Further analysis of actin and cytoskeletal related genes from patients with diabetic nephropathy suggests recapitulation of this programme during the development of renal disease. The Rho family member Cdc42 was also found uniquely to be activated in cells treated with TGFβ and CCN2; Cdc42 interacting genes were differentially regulated in diabetic nephropathy. CONCLUSIONS TGFβ and CCN2 attenuate CREB and augment E2F1 transcriptional activation with the likely effect of altering actin cytoskeletal and cell growth/hypertrophic gene activity with implications for cell dysfunction in diabetic kidney disease. The cytoskeletal regulator Cdc42 may play a role in this signalling response.
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Affiliation(s)
- Noel Faherty
- UCD School of Biomolecular and Biomedical Sciences, UCD Conway Institute, University College Dublin, Belfield, Dublin, Ireland
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55
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The C-terminal module IV of connective tissue growth factor is a novel immune modulator of the Th17 response. J Transl Med 2013; 93:812-24. [PMID: 23648563 DOI: 10.1038/labinvest.2013.67] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Connective tissue growth factor (CTGF/CCN2) is a matricellular protein susceptible to proteolytic degradation. CCN2 levels have been suggested as a potential risk biomarker in several chronic diseases. In body fluids, CCN2 full-length and its degradation fragments can be found; however, their in vivo effects are far from being elucidated. CCN2 was described as a profibrotic mediator, but this concept is changing to a proinflammatory cytokine. In vitro, CCN2 full-length and its C-terminal module IV (CCN2(IV)) exert proinflammatory properties. Emerging evidence suggest that Th17 cells, and its effector cytokine IL-17A, participate in chronic inflammatory diseases. Our aim was to explore whether CCN2(IV) could regulate the Th17 response. In vitro, stimulation of human naive CD4+ T lymphocytes with CCN2(IV) resulted in differentiation to Th17 phenotype. The in vivo effects of CCN2(IV) were studied in C57BL/6 mice. Intraperitoneal administration of recombinant CCN2(IV) did not change serum IL-17A levels, but caused an activation of the Th17 response in the kidney, characterized by interstitial infiltration of Th17 (IL17A+/CD4+) cells and upregulation of proinflammatory mediators. In CCN2(IV)-injected mice, elevated renal levels of Th17-related factors (IL-17A, IL-6, STAT3 and RORγt) were found, whereas Th1/Th2 cytokines or Treg-related factors (TGF-β and Foxp-3) were not modified. Treatment with an anti-IL-17A neutralizing antibody diminished CCN2(IV)-induced renal inflammation. Our findings unveil that the C-terminal module of CCN2 induces the Th17 differentiation of human Th17 cells and causes a renal Th17 inflammatory response. Furthermore, these data bear out that IL-17A targeting is a promising tool for chronic inflammatory diseases, including renal pathologies.
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Abstract
PURPOSE OF REVIEW Connective tissue growth factor, more recently officially known as CCN-2, is a member of the CCN family of secreted cysteine-rich modular matricellular proteins. Here, we review CCN-2 in diabetic nephropathy with focus on its regulation of extracellular matrix. RECENT FINDINGS CCN-2 is upregulated in the clinical and preclinical models of diabetic nephropathy by multiple stimuli, including elevated glucose, advanced glycation, some types of lipid, various hemodynamic factors, as well as hypoxia and oxidative stress. CCN-2 has bioactivities that suggest it may mediate diabetic nephropathy pathogenesis, especially in extracellular matrix accumulation, through both induction of new matrix and inhibition of matrix degradation. CCN-2 also has proinflammatory functions. Moreover, recent studies using antibodies or antisense technologies in animal and early phase clinical trial settings have shown that inhibition of renal CCN-2 expression or action may prevent diabetic nephropathy. Additionally, determination of renal and blood levels of CCN-2 as a marker of diabetic renal disease and its progression appears to have value. SUMMARY Recent publications implicate CCN-2 as both an evolving marker and mediator of diabetic nephropathy.
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Onuigbo M. Renoprotection and the Bardoxolone Methyl Story - Is This the Right Way Forward? A Novel View of Renoprotection in CKD Trials: A New Classification Scheme for Renoprotective Agents. NEPHRON EXTRA 2013; 3:36-49. [PMID: 23687511 PMCID: PMC3656681 DOI: 10.1159/000351044] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In the June 2011 issue of the New England Journal of Medicine, the BEAM (Bardoxolone Methyl Treatment: Renal Function in CKD/Type 2 Diabetes) trial investigators rekindled new interest and also some controversy regarding the concept of renoprotection and the role of renoprotective agents, when they reported significant increases in the mean estimated glomerular filtration rate (eGFR) in diabetic chronic kidney disease (CKD) patients with an eGFR of 20-45 ml/min/1.73 m(2) of body surface area at enrollment who received the trial drug bardoxolone methyl versus placebo. Unfortunately, subsequent phase IIIb trials failed to show that the drug is a safe alternative renoprotective agent. Current renoprotection paradigms depend wholly and entirely on angiotensin blockade; however, these agents [angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs)] have proved to be imperfect renoprotective agents. In this review, we examine the mechanistic limitations of the various previous randomized controlled trials on CKD renoprotection, including the paucity of veritable, elaborate and systematic assessment methods for the documentation and reporting of individual patient-level, drug-related adverse events. We review the evidence base for the presence of putative, multiple independent and unrelated pathogenetic mechanisms that drive (diabetic and non-diabetic) CKD progression. Furthermore, we examine the validity, or lack thereof, of the hyped notion that the blockade of a single molecule (angiotensin II), which can only antagonize the angiotensin cascade, would veritably successfully, consistently and unfailingly deliver adequate and qualitative renoprotection results in (diabetic and non-diabetic) CKD patients. We clearly posit that there is this overarching impetus to arrive at the inference that multiple, disparately diverse and independent pathways, including any veritable combination of the mechanisms that we examine in this review, and many more others yet to be identified, do concurrently and asymmetrically contribute to CKD initiation and propagation to end-stage renal disease (ESRD) in our CKD patients. We conclude that current knowledge of CKD initiation and progression to ESRD, the natural history of CKD and the impacts of acute kidney injury on this continuum remain in their infancy and call for more research. Finally, we suggest a new classification scheme for renoprotective agents: (1) the single-pathway blockers that block a single putative pathogenetic pathway involved in CKD progression, as typified by ACE inhibitors and/or ARBs, and (2) the multiple-pathway blockers that are able to block or antagonize the effects of multiple pathogenetic pathways through their ability to simultaneously block, downstream, the effects of several pathways or mechanisms of CKD to ESRD progression and could therefore concurrently interfere with several unrelated upstream pathways or mechanisms. We surmise that maybe the ideal and truly renoprotective agent, clearly a multiple-pathway blocker, is on the horizon. This calls for more research efforts from all.
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Affiliation(s)
- Macaulay Onuigbo
- College of Medicine, Mayo Clinic, Rochester, Minn., and Mayo Health System Practice-Based Research Network, and Department of Nephrology, Mayo Clinic Health System, Eau Claire, Wisc., USA
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Yokoi H, Kasahara M, Mori K, Kuwabara T, Toda N, Yamada R, Namoto S, Yamamoto T, Seki N, Souma N, Yamaguchi T, Sugawara A, Mukoyama M, Nakao K. Peritoneal fibrosis and high transport are induced in mildly pre-injured peritoneum by 3,4-dideoxyglucosone-3-ene in mice. Perit Dial Int 2012; 33:143-54. [PMID: 23123666 DOI: 10.3747/pdi.2011.00033] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Peritoneal dialysis (PD) solution contains high concentrations of glucose and glucose degradation products (GDPs). One of several GDPs--3,4-dideoxyglucosone-3-ene (3,4-DGE)--was recently identified as the most reactive and toxic GDP in PD fluids. In vitro, 3,4-DGE has been shown to induce mesothelial cell damage; however, its role in peritoneal fibrosis in vivo remains unclear. In the present study, we intraperitoneally administered chlorhexidine gluconate (CG) for mild peritoneal injury, and we then injected 3,4-DGE [38 μmol/L (low concentration) or 145 μmol/L (high concentration)] 5 times weekly for 4 weeks. Significant thickening of the parietal peritoneal membrane was observed only when treatment with low or high concentrations of 3,4-DGE occurred after CG administration, but not when either CG or 3,4-DGE alone was given. The combination of CG and 3,4-DGE also caused upregulation of messenger RNA expression of transforming growth factor β1, connective tissue growth factor, fibronectin, collagen type 1 α1 chain, alpha smooth muscle actin (α-SMA), vascular endothelial growth factor 164, NADPH oxidase 1 and 4, p22phox, p47phox, and gp91phox in peritoneal tissue. Treatment with CG alone was sufficient to cause significant F4/80-positive macrophage infiltration, appearance of α-SMA-positive cells, and vessel formation in the submesothelial layer. Addition of 3,4-DGE markedly enhanced those changes and induced apoptosis, mainly in leukocytes. The concentration of 3,4-DGE in the abdominal cavity declined more rapidly in CG-treated mice than in PBS-treated mice. Peritoneal membrane permeability determined by peritoneal equilibration test showed high transport conditions in peritoneum treated with both CG and 3,4-DGE. These results indicate that, when mild peritoneal damage is already present, 3,4-DGE causes peritoneal thickening and fibrosis, resulting in deterioration of peritoneal membrane function.
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Affiliation(s)
- Hideki Yokoi
- Department of Medicine and Clinical Science,Kyoto University Graduate School of Medicine, Kyoto, Japan
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Mason RM. Fell-Muir lecture: Connective tissue growth factor (CCN2) -- a pernicious and pleiotropic player in the development of kidney fibrosis. Int J Exp Pathol 2012; 94:1-16. [PMID: 23110747 DOI: 10.1111/j.1365-2613.2012.00845.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 08/21/2012] [Indexed: 01/01/2023] Open
Abstract
Connective tissue growth factor (CTGF, CCN2) is a member of the CCN family of matricellular proteins. It interacts with many other proteins, including plasma membrane proteins, modulating cell function. It is expressed at low levels in normal adult kidney cells but is increased in kidney diseases, playing important roles in inflammation and in the development of glomerular and interstitial fibrosis in chronic disease. This review reports the evidence for its expression in human and animal models of chronic kidney disease and summarizes data showing that anti-CTGF therapy can successfully attenuate fibrotic changes in several such models, suggesting that therapies targeting CTGF and events downstream of it in renal cells may be useful for the treatment of human kidney fibrosis. Connective tissue growth factor stimulates the development of fibrosis in the kidney in many ways including activating cells to increase extracellular matrix synthesis, inducing cell cycle arrest and hypertrophy, and prolonging survival of activated cells. The relationship between CTGF and the pro-fibrotic factor TGFβ is examined and mechanisms by which CTGF promotes signalling by the latter are discussed. No specific cellular receptors for CTGF have been discovered but it interacts with and activates several plasma membrane proteins including low-density lipoprotein receptor-related protein (LRP)-1, LRP-6, tropomyosin-related kinase A, integrins and heparan sulphate proteoglycans. Intracellular signalling and downstream events triggered by such interactions are reviewed. Finally, the relationships between CTGF and several anti-fibrotic factors, such as bone morphogenetic factor-4 (BMP4), BMP7, hepatocyte growth factor, CCN3 and Oncostatin M, are discussed. These may determine whether injured tissue heals or progresses to fibrosis.
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Affiliation(s)
- Roger M Mason
- Renal Section, Department of Medicine, Imperial College London, London, UK.
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Fragiadaki M, Hill N, Hewitt R, Bou-Gharios G, Cook T, Tam FW, Domin J, Mason RM. Hyperglycemia causes renal cell damage via CCN2-induced activation of the TrkA receptor: implications for diabetic nephropathy. Diabetes 2012; 61:2280-8. [PMID: 22586581 PMCID: PMC3425410 DOI: 10.2337/db11-1138] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
CCN2, a secreted profibrotic protein, is highly expressed in diabetic nephropathy (DN) and implicated in its pathogenesis; however, the actions of CCN2 in DN remain elusive. We previously demonstrated that CCN2 triggers signaling via tropomyosin receptor kinase A (TrkA). Trace expression of TrkA is found in normal kidneys, but its expression is elevated in several nephropathies; yet its role in DN is unexplored. In this study we show de novo expression of TrkA in human and murine DN. We go on to study the molecular mechanisms leading to TrkA activation and show that it involves hypoxia, as demonstrated by ischemia-reperfusion injury and in vitro experiments mimicking hypoxia, implicating hypoxia as a common pathway leading to disease. We also expose renal cells to hyperglycemia, which led to TrkA phosphorylation in mesangial cells, tubular epithelial cells, and podocytes but not in glomerular endothelial cells and renal fibroblasts. In addition, we report that hyperglycemia caused an induction of phosphorylated extracellular signal-related kinase 1/2 and Snail1 that was abrogated by silencing of TrkA or CCN2 using small interfering RNA. In conclusion, we provide novel evidence that TrkA is activated in diabetic kidneys and suggest that anti-TrkA therapy may prove beneficial in DN.
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Affiliation(s)
- Maria Fragiadaki
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
- Corresponding authors: Roger M. Mason, , and Maria Fragiadaki, or
| | - Nicola Hill
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
| | - Reiko Hewitt
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
| | - George Bou-Gharios
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
- Kennedy Institute of Rheumatology, Imperial College London, London, U.K
| | - Terence Cook
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
- Histopathology, Imperial College London, London, U.K
| | - Frederick W. Tam
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
| | - Jan Domin
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
- Division of Sciences, University of Bedfordshire, Luton, U.K
| | - Roger M. Mason
- Renal Section, Hammersmith Campus, Division of Inflammation and Immunology, Imperial College London, London, U.K
- Corresponding authors: Roger M. Mason, , and Maria Fragiadaki, or
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Kuwabara T, Mori K, Mukoyama M, Kasahara M, Yokoi H, Saito Y, Ogawa Y, Imamaki H, Kawanishi T, Ishii A, Koga K, Mori KP, Kato Y, Sugawara A, Nakao K. Exacerbation of diabetic nephropathy by hyperlipidaemia is mediated by Toll-like receptor 4 in mice. Diabetologia 2012; 55:2256-66. [PMID: 22610400 DOI: 10.1007/s00125-012-2578-1] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 04/04/2012] [Indexed: 12/24/2022]
Abstract
AIMS/HYPOTHESIS Hyperlipidaemia is an independent risk factor for the progression of diabetic nephropathy, but its molecular mechanism remains elusive. We investigated in mice how diabetes and hyperlipidaemia cause renal lesions separately and in combination, and the involvement of Toll-like receptor 4 (TLR4) in the process. METHODS Diabetes was induced in wild-type (WT) and Tlr4 knockout (KO) mice by intraperitoneal injection of streptozotocin (STZ). At 2 weeks after STZ injection, normal diet was substituted with a high-fat diet (HFD). Functional and histological analyses were carried out 6 weeks later. RESULTS Compared with treatment with STZ or HFD alone, treatment of WT mice with both STZ and HFD markedly aggravated nephropathy, as indicated by an increase in albuminuria, mesangial expansion, infiltration of macrophages and upregulation of pro-inflammatory and extracellular-matrix-associated gene expression in glomeruli. In Tlr4 KO mice, the addition of an HFD to STZ had almost no effects on the variables measured. Production of protein S100 calcium binding protein A8 (calgranulin A; S100A8), a potent ligand for TLR4, was observed in abundance in macrophages infiltrating STZ-HFD WT glomeruli and in glomeruli of diabetic nephropathy patients. High-glucose and fatty acid treatment synergistically upregulated S100a8 gene expression in macrophages from WT mice, but not from KO mice. As putative downstream targets of TLR4, phosphorylation of interferon regulatory factor 3 (IRF3) was enhanced in kidneys of WT mice co-treated with STZ and HFD. CONCLUSIONS/INTERPRETATION Activation of S100A8/TLR4 signalling was elucidated in an animal model of diabetic glomerular injury accompanied with hyperlipidaemia, which may provide novel therapeutic targets in progressive diabetic nephropathy.
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Affiliation(s)
- T Kuwabara
- Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, 54 Shogoin Kawaharacho, Sakyoku, Kyoto, 606-8507, Japan
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62
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Affiliation(s)
- Hui Yao Lan
- Li Ka Shing Institute of Health Sciences and Department of Medicine & Therapeutics, and CUHK Shenzhen Research Institute; The Chinese University of Hong Kong; Hong Kong; China
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63
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Sarközi R, Flucher K, Haller VM, Pirklbauer M, Mayer G, Schramek H. Oncostatin M inhibits TGF-β1-induced CTGF expression via STAT3 in human proximal tubular cells. Biochem Biophys Res Commun 2012; 424:801-6. [PMID: 22814105 DOI: 10.1016/j.bbrc.2012.07.042] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 07/10/2012] [Indexed: 11/26/2022]
Abstract
Matricellular proteins play a critical role in the development of tubulointerstitial fibrosis and renal disease progression. Connective tissue growth factor (CTGF/CCN2), a CCN family member of matricellular proteins, represents an important mediator during development of glomerular and tubulointerstitial fibrosis in progressive kidney disease. We have recently reported that oncostatin M (OSM) is a potent inhibitor of TGF-β1-induced CTGF expression in human proximal tubular cells (PTC). In the present study we examined the role of TGF-β1- and OSM-induced signaling mechanisms in the regulation of CTGF mRNA expression in human proximal tubular HK-2 cells. Utilizing siRNA-mediated gene silencing we found that TGF-β1-induced expression of CTGF mRNA after 2h of stimulation at least partially depends on SMAD3 but not on SMAD2. In contrast to TGF-β1, OSM seems to exert a time-dependent dual effect on CTGF mRNA expression in these cells. While OSM led to a rapid and transient induction of CTGF mRNA expression between 15 min and 1h of stimulation it markedly suppressed basal and TGF-β1-induced CTGF mRNA levels thereafter. Silencing of STAT1 or STAT3 attenuated basal CTGF mRNA levels indicating that both STAT isoforms may be involved in the regulation of basal CTGF mRNA expression. However, knockdown of STAT3 but not STAT1 prevented OSM-mediated suppression of basal and TGF-β1-induced upregulation of CTGF mRNA expression. Together these results suggest that the inhibitory effect of OSM on TGF-β1-induced CTGF mRNA expression is mainly driven by STAT3, thereby providing a signaling mechanism whereby OSM may contribute to tubulointerstitial protection.
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Affiliation(s)
- Rita Sarközi
- Department of Internal Medicine IV, Nephrology and Hypertension, Innsbruck Medical University, Innsbruck, Austria
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64
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Ogawa Y, Mukoyama M, Yokoi H, Kasahara M, Mori K, Kato Y, Kuwabara T, Imamaki H, Kawanishi T, Koga K, Ishii A, Tokudome T, Kishimoto I, Sugawara A, Nakao K. Natriuretic peptide receptor guanylyl cyclase-A protects podocytes from aldosterone-induced glomerular injury. J Am Soc Nephrol 2012; 23:1198-209. [PMID: 22652704 DOI: 10.1681/asn.2011100985] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Natriuretic peptides produced by the heart in response to cardiac overload exert cardioprotective and renoprotective effects by eliciting natriuresis, reducing BP, and inhibiting cell proliferation and fibrosis. These peptides also antagonize the renin-angiotensin-aldosterone system, but whether this mechanism contributes to their renoprotective effect is unknown. Here, we examined the kidneys of mice lacking the guanylyl cyclase-A (GC-A) receptor for natriuretic peptides under conditions of high aldosterone and high dietary salt. After 4 weeks of administering aldosterone and a high-salt diet, GC-A knockout mice, but not wild-type mice, exhibited accelerated hypertension with massive proteinuria. Aldosterone-infused GC-A knockout mice had marked mesangial expansion, segmental sclerosis, severe podocyte injury, and increased oxidative stress. Reducing the BP with hydralazine failed to lessen such changes; in contrast, blockade of the renin-angiotensin-aldosterone system markedly reduced albuminuria, ameliorated podocyte injury, and reduced oxidative stress. Furthermore, treatment with the antioxidant tempol significantly reduced albuminuria and abrogated the histologic changes. In cultured podocytes, natriuretic peptides inhibited aldosterone-induced mitogen-activated protein kinase phosphorylation. Taken together, these results suggest that renoprotective properties of the endogenous natriuretic peptide/GC-A system may result from the local inhibition of the renin-angiotensin-aldosterone system and oxidative stress in podocytes.
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Affiliation(s)
- Yoshihisa Ogawa
- Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, Japan
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Gnudi L. Cellular and molecular mechanisms of diabetic glomerulopathy. Nephrol Dial Transplant 2012; 27:2642-9. [DOI: 10.1093/ndt/gfs121] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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66
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Hübner S, Efthymiadis A. Recent progress in histochemistry and cell biology. Histochem Cell Biol 2012; 137:403-57. [PMID: 22366957 DOI: 10.1007/s00418-012-0933-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2012] [Indexed: 01/06/2023]
Abstract
Studies published in Histochemistry and Cell Biology in the year 2011 represent once more a manifest of established and newly sophisticated techniques being exploited to put tissue- and cell type-specific molecules into a functional context. The review is therefore the Histochemistry and Cell Biology's yearly intention to provide interested readers appropriate summaries of investigations touching the areas of tissue biology, developmental biology, the biology of the immune system, stem cell research, the biology of subcellular compartments, in order to put the message of such studies into natural scientific-/human- and also pathological-relevant correlations.
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Affiliation(s)
- Stefan Hübner
- Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg, Germany.
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Abstract
Diabetic nephropathy is the major cause of end-stage renal disease worldwide. Although the renin-angiotensin system has been implicated in the pathogenesis of diabetic nephropathy, angiotensin I-converting enzyme inhibitors have a beneficial effect on diabetic nephropathy independently of their effects on blood pressure and plasma angiotensin II levels. This suggests that the kallikrein-kinin system (KKS) is also involved in the disease. To study the role of the KKS in diabetic nephropathy, mice lacking either the bradykinin B1 receptor (B1R) or the bradykinin B2 receptor (B2R) have been commonly used. However, because absence of either receptor causes enhanced expression of the other, it is difficult to determine the precise functions of each receptor. This difficulty has recently been overcome by comparing mice lacking both receptors with mice lacking each receptor. Deletion of both B1R and B2R reduces nitric oxide (NO) production and aggravates renal diabetic phenotypes, relevant to either lack of B1R or B2R, demonstrating that both B1R and B2R exert protective effects on diabetic nephropathy presumably via NO. Here, we review previous epidemiological and experimental studies, and discuss novel insights regarding the therapeutic implications of the importance of the KKS in averting diabetic nephropathy.
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Dai HY, Zheng M, Lv LL, Tang RN, Ma KL, Liu D, Wu M, Liu BC. The roles of connective tissue growth factor and integrin-linked kinase in high glucose-induced phenotypic alterations of podocytes. J Cell Biochem 2011; 113:293-301. [DOI: 10.1002/jcb.23355] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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69
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Taking aim at the extracellular matrix: CCN proteins as emerging therapeutic targets. Nat Rev Drug Discov 2011; 10:945-63. [PMID: 22129992 DOI: 10.1038/nrd3599] [Citation(s) in RCA: 496] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Members of the CCN family of matricellular proteins are crucial for embryonic development and have important roles in inflammation, wound healing and injury repair in adulthood. Deregulation of CCN protein expression or activities contributes to the pathobiology of various diseases - many of which may arise when inflammation or tissue injury becomes chronic - including fibrosis, atherosclerosis, arthritis and cancer, as well as diabetic nephropathy and retinopathy. Emerging studies indicate that targeting CCN protein expression or signalling pathways holds promise in the development of diagnostics and therapeutics for such diseases. This Review summarizes the biology of CCN proteins, their roles in various pathologies and their potential as therapeutic targets.
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Hall-Glenn F, Lyons KM. Roles for CCN2 in normal physiological processes. Cell Mol Life Sci 2011; 68:3209-17. [PMID: 21858450 PMCID: PMC3670951 DOI: 10.1007/s00018-011-0782-7] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 07/19/2011] [Accepted: 07/19/2011] [Indexed: 12/13/2022]
Abstract
CCN2, also known as connective tissue growth factor, is a member of the CCN (CCN1-6) family of modular matricellular proteins. Analysis of CCN2 function in vivo has focused primarily on its key role as a mediator of excess ECM synthesis in multiple fibrotic diseases. However, CCN2 and related family members are widely expressed during development. Recent studies using new genetic models are revealing that CCN2 has essential roles in the development of many tissues. This review focuses on current and emerging data on CCN2 and its functions in chondrogenesis and angiogenesis, and on new studies showing that CCN2 has essential functions during embryonic and postnatal development in a number of epithelial tissues.
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Affiliation(s)
- Faith Hall-Glenn
- Department of Molecular, Cell and Developmental Biology, UCLA/Orthopaedic Hospital Department of Orthopaedic Surgery, University of California, 510 Orthopaedic Hospital Research Center, 615 Charles E Young Drive South, Los Angeles, CA 90095 USA
| | - Karen M. Lyons
- Department of Molecular, Cell and Developmental Biology, UCLA/Orthopaedic Hospital Department of Orthopaedic Surgery, University of California, 510 Orthopaedic Hospital Research Center, 615 Charles E Young Drive South, Los Angeles, CA 90095 USA
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71
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Pleiotrophin triggers inflammation and increased peritoneal permeability leading to peritoneal fibrosis. Kidney Int 2011; 81:160-9. [PMID: 21881556 DOI: 10.1038/ki.2011.305] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Long-term peritoneal dialysis induces peritoneal fibrosis with submesothelial fibrotic tissue. Although angiogenesis and inflammatory mediators are involved in peritoneal fibrosis, precise molecular mechanisms are undefined. To study this, we used microarray analysis and compared gene expression profiles of the peritoneum in control and chlorhexidine gluconate (CG)-induced peritoneal fibrosis mice. One of the 43 highly upregulated genes was pleiotrophin, a midkine family member, the expression of which was also upregulated by the solution used to treat mice by peritoneal dialysis. This growth factor was found in fibroblasts and mesothelial cells within the underlying submesothelial compact zones of mice, and in human peritoneal biopsy samples and peritoneal dialysate effluent. Recombinant pleiotrophin stimulated mitogenesis and migration of mouse mesothelial cells in culture. We found that in wild-type mice, CG treatment increased peritoneal permeability (measured by equilibration), increased mRNA expression of TGF-β1, connective tissue growth factor and fibronectin, TNF-α and IL-1β expression, and resulted in infiltration of CD3-positive T cells, and caused a high number of Ki-67-positive proliferating cells. All of these parameters were decreased in peritoneal tissues of CG-treated pleiotrophin-knockout mice. Thus, an upregulation of pleiotrophin appears to play a role in fibrosis and inflammation during peritoneal injury.
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Interstitial fibrosis is associated with increased COL1A2 transcription in AA-injured renal tubular epithelial cells in vivo. Matrix Biol 2011; 30:396-403. [PMID: 21864682 DOI: 10.1016/j.matbio.2011.07.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 07/14/2011] [Accepted: 07/28/2011] [Indexed: 01/19/2023]
Abstract
Accumulation of type I collagen is a key event in renal interstitial fibrosis. As there is no effective treatment, understanding the site where collagen is transcribed and the factors driving it in response to disease in vivo is critical for designing future therapies. The present research investigated the transcriptional activity of the COL1A2 gene in a mouse model of progressive fibrosis induced by aristolochic acid (aristolochic acid nephropathy, AAN). To achieve this we genetically modified mice to express a reporter gene (LacZ) and CCN2 (connective tissue growth factor) under the transcriptional control of the COL1A2 promoter /enhancer sequences. Using these mice we asked where is collagen actively transcribed and secondly, what is the role of CCN2 in AAN. Here, we report that de-novo transcription of the COL1A2 gene occurred predominantly in damaged tubular epithelial cells during progressive interstitial fibrosis in vivo. The activation of COL1A2 was studied by detection of the reporter gene LacZ and COL1A2 mRNA in interstitial, glomerular, vascular, and tubular epithelial tissue from laser capture microscopy. We also demonstrated that LacZ-positive cells co-express E-Cadherin a marker of epithelial origin which is consistent with an epithelial phenotype which is capable of collagen expression during injury. There was no evidence of detachment of these cells from tubules to become myofibroblasts. Moreover, we showed that the transgenic mice show a modest enhancement of CCN2 expression; however fibrosis induced by AA is the same in transgenics and controls suggesting that CCN2, at this level of expression, is not sufficient to enhance fibrogenesis. Overall our study provides a better understanding into the expression patterns and roles of two major extracellular matrix proteins: type I collagen and CCN2.
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Connective tissue growth factor modulates podocyte actin cytoskeleton and extracellular matrix synthesis and is induced in podocytes upon injury. Histochem Cell Biol 2011; 136:301-19. [DOI: 10.1007/s00418-011-0844-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2011] [Indexed: 12/19/2022]
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Sarközi R, Hauser C, Noppert SJ, Kronbichler A, Pirklbauer M, Haller VM, Grillari J, Grillari-Voglauer R, Mayer G, Schramek H. Oncostatin M is a novel inhibitor of TGF-β1-induced matricellular protein expression. Am J Physiol Renal Physiol 2011; 301:F1014-25. [PMID: 21816755 DOI: 10.1152/ajprenal.00123.2011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Matricellular proteins in the kidney have been associated with the development of tubulointerstitial fibrogenesis and the progression of renal disease. This study investigated potential antifibrotic effects of the cytokine oncostatin M (OSM) in human proximal tubule cells (PTC), particularly with regard to inhibition of profibrotic events initiated by TGF-β1. In human PTC, OSM diminished transforming growth factor (TGF)-β1-induced expression of the transcriptional epithelial-mesenchymal transition mediator FoxC2. Furthermore, exposure to OSM attenuated basal and TGF-β1-induced expression of the matricellular proteins SPARC, TSP-1, TNC, and CTGF regardless of the sequence of ligand administration. OSM was shown to result in rapid and sustained phosphorylation of both Stat1 and Stat3 and also in transient phosphorylation of Smad2/3 in contrast to TGF-β1, which demonstrated a gradually building phosphorylation of Smad2/3 and a brief phosphorylation of Smad1/5/8. Utilizing receptor-blocking molecules, we found the inhibitory effect of OSM on TGF-β1-induced CTGF mRNA expression occurs independently of Smad2/3 signaling and present evidence that this effect may be partially driven by OSM receptor-mediated Stat1 and/or Stat3 signaling pathways, thereby providing a mechanism whereby OSM can contribute to tubulointerstitial protection.
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Affiliation(s)
- Rita Sarközi
- Department of Internal Medicine IV, Nephrology and Hypertension, Innsbruck Medical University, Innsbruck, Austria
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75
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Slagman MCJ, Nguyen TQ, Waanders F, Vogt L, Hemmelder MH, Laverman GD, Goldschmeding R, Navis G. Effects of antiproteinuric intervention on elevated connective tissue growth factor (CTGF/CCN-2) plasma and urine levels in nondiabetic nephropathy. Clin J Am Soc Nephrol 2011; 6:1845-50. [PMID: 21784839 DOI: 10.2215/cjn.08190910] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND OBJECTIVES Connective tissue growth factor (CTGF/CCN-2) is a key player in fibrosis. Plasma CTGF levels predict end-stage renal disease and mortality in diabetic chronic kidney disease (CKD), supporting roles in intra- and extrarenal fibrosis. Few data are available on CTGF in nondiabetic CKD. We investigated CTGF levels and effects of antiproteinuric interventions in nondiabetic proteinuric CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS In a crossover randomized controlled trial, 33 nondiabetic CKD patients (3.2 [2.5 to 4.0] g/24 h proteinuria) were treated during 6-week periods with placebo, ARB (100 mg/d losartan), and ARB plus diuretics (100 mg/d losartan plus 25 mg/d hydrochlorothiazide) combined with consecutively regular and low sodium diets (193 ± 62 versus 93 ± 52 mmol Na(+)/d). RESULTS CTGF was elevated in plasma (464 [387 to 556] pmol/L) and urine (205 [135 to 311] pmol/24 h) of patients compared with healthy controls (n = 21; 96 [86 to 108] pmol/L and 73 [55 to 98] pmol/24 h). Urinary CTGF was lowered by antiproteinuric intervention, in proportion to the reduction of proteinuria, with normalization during triple therapy (CTGF 99 [67 to 146] in CKD versus 73 [55 to 98] pmol/24 h in controls). In contrast, plasma CTGF was not affected. CONCLUSIONS Urinary and plasma CTGF are elevated in nondiabetic CKD. Only urinary CTGF is normalized by antiproteinuric intervention, consistent with amelioration of tubular dysfunction. The lack of effect on plasma CTGF suggests that its driving force might be independent of proteinuria and that short-term antiproteinuric interventions are not sufficient to correct the systemic profibrotic state in CKD.
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Affiliation(s)
- Maartje C J Slagman
- University Medical Center Groningen, Department of Internal Medicine, Division of Nephrology, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
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Mathew A, Cunard R, Sharma K. Antifibrotic treatment and other new strategies for improving renal outcomes. CONTRIBUTIONS TO NEPHROLOGY 2011; 170:217-227. [PMID: 21659774 PMCID: PMC4124634 DOI: 10.1159/000325671] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Diabetic nephropathy (DN) is clinically characterized by proteinuria and hypertension. Investigations suggest that matrix accumulation and inflammatory processes contribute to the pathological features of this progressive disease. This chapter reviews novel targeted approaches to the treatment of DN, with the goal of slowing the progression and improving renal function. Many studies support the use of agents that block the renin-angiotensin-aldosterone system in DN. Novel, oral agents that are promising in early clinical studies are agents such as pirfenidone and bardoxolone as they are associated with early improvement in renal function in patients with advanced diabetic kidney disease. Additionally, strategies that inhibit inflammatory cytokines, chemokines, adhesion molecules and mediators of the innate immune response may provide novel targets for the treatment of DN. Larger clinical studies are eagerly awaited to determine if new agents that specifically block kidney fibrosis and inflammation will delay, arrest and possibly reverse progressive renal failure.
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Affiliation(s)
- Anna Mathew
- Center for Renal Translational Medicine, Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, San Diego, Calif., USA
- Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, San Diego, Calif., USA
| | - Robyn Cunard
- Center for Renal Translational Medicine, Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, San Diego, Calif., USA
- Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, San Diego, Calif., USA
| | - Kumar Sharma
- Center for Renal Translational Medicine, Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, San Diego, Calif., USA
- Veterans Affairs San Diego Healthcare System, Veterans Medical Research Foundation, San Diego, Calif., USA
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Mechanisms and consequences of TGF-ß overexpression by podocytes in progressive podocyte disease. Cell Tissue Res 2011; 347:129-40. [PMID: 21541658 PMCID: PMC3250617 DOI: 10.1007/s00441-011-1169-7] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 04/04/2011] [Indexed: 01/21/2023]
Abstract
In patients with progressive podocyte disease, such as focal segmental glomerulosclerosis (FSGS) and membranous nephropathy, upregulation of transforming growth factor-ß (TGF-ß) is observed in podocytes. Mechanical pressure or biomechanical strain in podocytopathies may cause overexpression of TGF-ß and angiotensin II (Ang II). Oxidative stress induced by Ang II may activate the latent TGF-ß, which then activates Smads and Ras/extracellular signal-regulated kinase (ERK) signaling pathways in podocytes. Enhanced TGF-ß activity in podocytes may lead to thickening of the glomerular basement membrane (GBM) by overproduction of GBM proteins and impaired GBM degradation in podocyte disease. It may also lead to podocyte apoptosis and detachment from the GBM, and epithelial-mesenchymal transition (EMT) of podocytes, initiating the development of glomerulosclerosis. Furthermore, activated TGF-ß/Smad signaling by podocytes may induce connective tissue growth factor and vascular endothelial growth factor overexpression, which could act as a paracrine effector mechanism on mesangial cells to stimulate mesangial matrix synthesis. In proliferative podocytopathies, such as cellular or collapsing FSGS, TGF-ß-induced ERK activation may play a role in podocyte proliferation, possibly via TGF-ß-induced EMT of podocytes. Collectively, these data bring new mechanistic insights into our understanding of the TGF-ß overexpression by podocytes in progressive podocyte disease.
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78
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Kushwaha S, Vikram A, Jena GB. Protective effects of enalapril in streptozotocin-induced diabetic rat: studies of DNA damage, apoptosis and expression of CCN2 in the heart, kidney and liver. J Appl Toxicol 2011; 32:662-72. [DOI: 10.1002/jat.1670] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 01/11/2011] [Accepted: 01/19/2011] [Indexed: 01/09/2023]
Affiliation(s)
- S. Kushwaha
- Department of Pharmacology and Toxicology; National Institute of Pharmaceutical Education and Research; Sector-67, S.A.S. Nagar; Punjab; 160062; India
| | - A. Vikram
- Department of Pharmacology and Toxicology; National Institute of Pharmaceutical Education and Research; Sector-67, S.A.S. Nagar; Punjab; 160062; India
| | - G. B. Jena
- Department of Pharmacology and Toxicology; National Institute of Pharmaceutical Education and Research; Sector-67, S.A.S. Nagar; Punjab; 160062; India
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Fujinaka H, Katsuyama K, Yamamoto K, Nameta M, Yoshida Y, Yaoita E, Tomizawa S, Yamamoto T. Expression and localization of insulin-like growth factor binding proteins in normal and proteinuric kidney glomeruli. Nephrology (Carlton) 2011; 15:700-9. [PMID: 21040165 DOI: 10.1111/j.1440-1797.2010.01285.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM Insulin-like growth factor I (IGF-I) acts on target cells in an endocrine and/or local manner through the IGF-I receptor (IGF-IR), and its actions are modulated by multiple IGF binding proteins (IGFBP). To elucidate the roles of local IGFBP in kidney glomeruli, the expression and localization of their genes were examined and compared with normal and proteinuric kidney glomeruli. METHODS A cDNA microarray database (MAd-761) was constructed using human kidney glomeruli and cortices. The gene expression levels of IGF-I, IGF-1R and IGFBP (1-10) were examined in glomeruli and cortices by polymerase chain reaction (PCR) and in situ hybridization (ISH), and the expression levels of IGFBP that were abundantly found in the glomerulus were compared between normal and proteinuric kidneys in rats and humans. RESULTS IGFBP-2, -7 and -8 were demonstrated to be abundantly and preferentially expressed in the glomerulus. In PCR, the expression levels of the IGFBP-2, -7, -8 and -10 genes in glomeruli were shown to have more than doubled compared with their levels in the cortices. In ISH, the IGFBP-2, -7, -8 and -10 genes were found to be localized in glomerular cells including podocytes, and their increased expression was observed in inflammatory glomeruli. IGF-I gene expression was localized in glomerular podocytes, whereas the IGF-IR gene was expressed in glomerular podocytes and cortical tubular cells. In nephrotic rats, the expression of the IGFBP-10 gene was increased in glomerular podocytes; however, the expression levels of IGFBP-2, -7 and -8 did not change. CONCLUSION IGFBP-2, -7, -8 and -10 are produced by normal and injured glomerular podocytes and may regulate local IGF-I actions in podocytes and/or cortical tubular cells in the kidney.
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Affiliation(s)
- Hidehiko Fujinaka
- Institute for Clinical Research, Niigata National Hospital, Kashiwazaki, Japan.
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80
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Mastering a mediator: blockade of CCN-2 shows early promise in human diabetic kidney disease. J Cell Commun Signal 2010; 4:189-96. [PMID: 21234125 DOI: 10.1007/s12079-010-0102-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Accepted: 10/04/2010] [Indexed: 12/13/2022] Open
Abstract
In diabetes complications, CCN-2 (known originally as CTGF) has been implicated in diabetic nephropathy both as a marker and a mediator of disease. This commentary addresses CCN-2 in diabetic nephropathy, in the context of the recent publication of the first human study to inhibit CCN-2 bioactivity in diabetic kidney disease.
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81
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Doherty HE, Kim HS, Hiller S, Sulik KK, Maeda N. A mouse strain where basal connective tissue growth factor gene expression can be switched from low to high. PLoS One 2010; 5:e12909. [PMID: 20877562 PMCID: PMC2943916 DOI: 10.1371/journal.pone.0012909] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Accepted: 08/17/2010] [Indexed: 02/04/2023] Open
Abstract
Connective tissue growth factor (CTGF) is a signaling molecule that primarily functions in extracellular matrix maintenance and repair. Increased Ctgf expression is associated with fibrosis in chronic organ injury. Studying the role of CTGF in fibrotic disease in vivo, however, has been hampered by perinatal lethality of the Ctgf null mice as well as the limited scope of previous mouse models of Ctgf overproduction. Here, we devised a new approach and engineered a single mutant mouse strain where the endogenous Ctgf-3' untranslated region (3'UTR) was replaced with a cassette containing two 3'UTR sequences arranged in tandem. The modified Ctgf allele uses a 3'UTR from the mouse FBJ osteosarcoma oncogene (c-Fos) and produces an unstable mRNA, resulting in 60% of normal Ctgf expression (Lo allele). Upon Cre-expression, excision of the c-Fos-3'UTR creates a transcript utilizing the more stable bovine growth hormone (bGH) 3'UTR, resulting in increased Ctgf expression (Hi allele). Using the Ctgf Lo and Hi mutants, and crosses to a Ctgf knockout or Cre-expressing mice, we have generated a series of strains with a 30-fold range of Ctgf expression. Mice with the lowest Ctgf expression, 30% of normal, appear healthy, while a global nine-fold overexpression of Ctgf causes abnormalities, including developmental delay and craniofacial defects, and embryonic death at E10-12. Overexpression of Ctgf by tamoxifen-inducible Cre in the postnatal life, on the other hand, is compatible with life. The Ctgf Lo-Hi mutant mice should prove useful in further understanding the function of CTGF in fibrotic diseases. Additionally, this method can be used for the production of mouse lines with quantitative variations in other genes, particularly with genes that are broadly expressed, have distinct functions in different tissues, or where altered gene expression is not compatible with normal development.
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Affiliation(s)
- Heather E. Doherty
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Pathology and Laboratory Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Hyung-Suk Kim
- Department of Pathology and Laboratory Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sylvia Hiller
- Department of Pathology and Laboratory Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Kathleen K. Sulik
- Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Nobuyo Maeda
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Pathology and Laboratory Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
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Charrier A, Brigstock DR. Connective tissue growth factor production by activated pancreatic stellate cells in mouse alcoholic chronic pancreatitis. J Transl Med 2010; 90:1179-88. [PMID: 20368699 PMCID: PMC2901405 DOI: 10.1038/labinvest.2010.82] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Alcoholic chronic pancreatitis (ACP) is characterized by pancreatic necrosis, inflammation, and scarring, the latter of which is due to excessive collagen deposition by activated pancreatic stellate cells (PSC). The aim of this study was to establish a model of ACP in mice, a species that is usually resistant to the toxic effects of alcohol, and to identify the cell type(s) responsible for production of connective tissue growth factor (CTGF), a pro-fibrotic molecule. C57Bl/6 male mice received intraperitoneal ethanol injections for 3 weeks against a background of cerulein-induced acute pancreatitis. Peak blood alcohol levels remained consistently high in ethanol-treated mice as compared with control mice. In mice receiving ethanol plus cerulein, there was increased collagen deposition as compared with other treatment groups as well as increased frequency of alpha-smooth muscle actin and desmin-positive PSC, which also showed significantly enhanced CTGF protein production. Expression of mRNA for collagen alpha1(I), alpha-smooth muscle actin or CTGF were all increased and co-localized exclusively to activated PSC in ACP. Pancreatic expression of mRNA for key profibrotic markers were all increased in ACP. In conclusion, a mouse model of ACP has been developed that mimics key pathophysiological features of the disease in humans and which shows that activated PSC are the principal producers of collagen and CTGF. PSC-derived CTGF is thus a candidate therapeutic target in anti-fibrotic strategies for ACP.
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Affiliation(s)
- Alyssa Charrier
- Center for Clinical and Translational Research, The Research Institute at Nationwide Children’s Hospital, Columbus OH 43205,Molecular, Cellular and Developmental Biology Program, The Ohio State University, Columbus OH 43212
| | - David R. Brigstock
- Center for Clinical and Translational Research, The Research Institute at Nationwide Children’s Hospital, Columbus OH 43205,Molecular, Cellular and Developmental Biology Program, The Ohio State University, Columbus OH 43212,Departments of Surgery and Molecular & Cellular Biochemistry, The Ohio State University, Columbus OH 43212,Address correspondence to: David R. Brigstock, Room WA2022, Center for Clinical and Translational Research, The Research Institute at Nationwide Children’s Hospital, 700 Children’s Drive, Columbus OH 43205. Tel 614-355-2824; Fax 614-722-5892;
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83
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Cilnidipine suppresses podocyte injury and proteinuria in metabolic syndrome rats: possible involvement of N-type calcium channel in podocyte. J Hypertens 2010; 28:1034-43. [PMID: 20411599 DOI: 10.1097/hjh.0b013e328336ade3] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVES Clinical studies have indicated the beneficial effect of an L/N-type calcium channel blocker (CCB), cilnidipine, on the progression of proteinuria in hypertensive patients compared with an L-type CCB, amlodipine. In the present study, we examined the effects of cilnidipine and amlodipine on the renal injury in spontaneously hypertensive rat/ND mcr-cp (SHR/ND) and their underlying mechanism. METHODS AND RESULTS SHR/ND were treated with vehicle (nU10), cilnidipine [33 mg/kg per day, orally (p.o.); nU11] or amlodipine (20 mg/kg per day, p.o.; nU9) for 20 weeks. SHR/ND developed proteinuria in an age-dependent manner. Cilnidipine suppressed the proteinuria greater than amlodipine did. The immunohistochemical analysis showed that N-type calcium channel and Wilm's tumor factor, a marker of podocyte, were co-expressed. SHR/ND had significantly greater desmin staining, an indicator of podocyte injury, with lower podocin and nephrin expression in the glomeruli than Wistar-Kyoto rat or SHR. Cilnidipine significantly prevented the increase in desmin staining and restored the glomerular podocin and nephrin expression compared with amlodipine. Cilnidipine also prevented the increase in renal angiotensin II content, the expression and membrane translocation of NADPH oxidase subunits and dihydroethidium staining in SHR/ND. In contrast, amlodipine failed to change these renal parameters. CONCLUSION These data suggest that cilnidipine suppressed the development of proteinuria greater than amlodipine possibly through inhibiting N-type calcium channel-dependent podocyte injury in SHR/ND.
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84
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Ito Y, Goldschmeding R, Kasuga H, Claessen N, Nakayama M, Yuzawa Y, Sawai A, Matsuo S, Weening JJ, Aten J. Expression patterns of connective tissue growth factor and of TGF-beta isoforms during glomerular injury recapitulate glomerulogenesis. Am J Physiol Renal Physiol 2010; 299:F545-58. [PMID: 20576680 DOI: 10.1152/ajprenal.00120.2009] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Transforming growth factor (TGF)-beta(1), -beta(2), and -beta(3) are involved in control of wound repair and development of fibrosis. Connective tissue growth factor (CTGF) expression is stimulated by all TGF-beta isoforms and is abundant in glomerulosclerosis and other fibrotic disorders. CTGF is hypothesized to mediate profibrotic effects of TGF-beta(1) or to facilitate interaction of TGF-beta(1) with its receptor, but its interactions with TGF-beta isoforms in nonpathological conditions are unexplored so far. Tissue repair and remodeling may recapitulate gene transcription at play in organogenesis. To further delineate the relationship between CTGF and TGF-beta, we compared expression patterns of CTGF and TGF-beta isoforms in rat and human glomerulogenesis and in various human glomerulopathies. CTGF mRNA was present in the immediate precursors of glomerular visceral and parietal epithelial cells in the comma- and S-shaped stages, but not in earlier stages of nephron development. During the capillary loop and maturing glomerular stages and simultaneous with the presence of TGF-beta(1), -beta(2), and -beta(3) protein, CTGF mRNA expression was maximal and present only in differentiating glomerular epithelial cells. CTGF protein was also present on precursors of mesangium and glomerular endothelium, suggesting possible paracrine interaction. Concomitant with the presence of TGF-beta(2) and -beta(3) protein, and in the absence of TGF-beta(1), CTGF mRNA and protein expression was restricted to podocytes in normal adult glomeruli. However, TGF-beta(1) and CTGF were again coexpressed, often with TGF-beta(2) and -beta(3), in particular in podocytes in proliferative glomerulonephritis and also in mesangial cells in diabetic nephropathy and IgA nephropathy (IgA NP). Coordinated expression of TGF-beta isoforms and of CTGF may be involved in normal glomerulogenesis and possibly in maintenance of glomerular structure and function at adult age. Prolonged overexpression of TGF-beta(1) and CTGF is associated with development of severe glomerulonephritis and glomerulosclerosis.
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Affiliation(s)
- Yasuhiko Ito
- Department of Pathology, Academic Medical Center, University of Amsterdam, The Netherlands
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85
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Sonnylal S, Shi-Wen X, Leoni P, Naff K, Van Pelt CS, Nakamura H, Leask A, Abraham D, Bou-Gharios G, de Crombrugghe B. Selective expression of connective tissue growth factor in fibroblasts in vivo promotes systemic tissue fibrosis. ACTA ACUST UNITED AC 2010; 62:1523-32. [PMID: 20213804 DOI: 10.1002/art.27382] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Connective tissue growth factor (CTGF) is a cysteine-rich secreted matricellular protein involved in wound healing and tissue repair. Enhanced and prolonged expression of CTGF has been associated with tissue fibrosis in humans. However, questions remain as to whether CTGF expression alone is sufficient to drive fibrosis. This study was undertaken to investigate whether CTGF alone is sufficient to cause fibrosis in intact animals and whether its effects are mediated through activation of transforming growth factor beta (TGFbeta) signaling or through distinct signal transduction pathways. METHODS We generated mice overexpressing CTGF in fibroblasts under the control of the fibroblast-specific collagen alpha2(I) promoter enhancer. Tissues such as skin, lung, and kidney were harvested for histologic analysis. Mouse embryonic fibroblasts were prepared from embryos (14.5 days postcoitum) for biochemical analysis. RESULTS Mice overexpressing CTGF in fibroblasts were susceptible to accelerated tissue fibrosis affecting the skin, lung, kidney, and vasculature, most notably the small arteries. We identified a marked expansion of the myofibroblast cell population in the dermis. RNA analysis of transgenic dermal fibroblasts revealed elevated expression of key matrix genes, consistent with a fibrogenic response. CTGF induced phosphorylation of p38, ERK-1/2, JNK, and Akt, but not Smad3, in transgenic mouse fibroblasts compared with wild-type mouse fibroblasts. Transfection experiments showed significantly increased basal activity of the CTGF and serum response element promoters, and enhanced induction of the CTGF promoter in the presence of TGFbeta. CONCLUSION These results demonstrate that selective expression of CTGF in fibroblasts alone causes tissue fibrosis in vivo through specific signaling pathways, integrating cues from the extracellular matrix into signal transduction pathways to orchestrate pivotal biologic responses relevant to tissue repair and fibrosis.
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Affiliation(s)
- Sonali Sonnylal
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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Adler SG, Schwartz S, Williams ME, Arauz-Pacheco C, Bolton WK, Lee T, Li D, Neff TB, Urquilla PR, Sewell KL. Phase 1 study of anti-CTGF monoclonal antibody in patients with diabetes and microalbuminuria. Clin J Am Soc Nephrol 2010; 5:1420-8. [PMID: 20522536 DOI: 10.2215/cjn.09321209] [Citation(s) in RCA: 161] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND AND OBJECTIVES This report summarizes the first phase 1 trial treating patients with microalbuminuric diabetic kidney disease (DKD) using FG-3019, a human monoclonal antibody to connective tissue growth factor (CTGF). CTGF is critically involved in processes of progressive fibrosis, including DKD. This phase 1, open-label, dose-escalation trial evaluated safety, pharmacokinetics, and possible therapeutic effects of FG-3019 on albuminuria, proteinuria, and tubular proteins. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS Microalbuminuric subjects (n = 24) with type 2 (79%) or type 1 (21%) diabetes received 3 or 10 mg/kg FG-3019 dosed intravenously every 14 days for four doses. Albuminuria and safety follow-up were to days 62 and 365, respectively. RESULTS No infusion was interrupted for symptoms, although 5 of 24 subjects had mild infusion-day adverse events thought to be possibly drug-related. No subject developed anti-FG-3019 antibodies. FG-3019 clearance was lower at 10 mg/kg than at 3 mg/kg, suggesting a saturable elimination pathway. Although this study was not designed for efficacy testing, it was notable that urinary albumin/creatinine ratio (ACR) decreased significantly from mean pretreatment ACR of 48 mg/g to mean post-treatment (day 56) ACR of 20 mg/g (P = 0.027) without evidence for a dose-response relationship. CONCLUSIONS Treatment of microalbuminuric DKD subjects using FG-3019 was well tolerated and associated with a decrease in albuminuria. The data demonstrate a saturable pathway for drug elimination, minimal infusion adverse events, and no significant drug-attributable adverse effects over the year of follow-up. Changes in albuminuria were promising but require validation in a prospective, randomized, blinded study.
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Affiliation(s)
- Sharon G Adler
- Division of Nephrology and Hypertension, Los Angeles BioMedical Research Institute, Torrance, California 90502, USA.
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87
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Lack of both bradykinin B1 and B2 receptors enhances nephropathy, neuropathy, and bone mineral loss in Akita diabetic mice. Proc Natl Acad Sci U S A 2010; 107:10190-5. [PMID: 20479236 DOI: 10.1073/pnas.1005144107] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
An insertion polymorphism of the angiotensin-I converting enzyme gene (ACE) is common in humans and the higher expressing allele is associated with an increased risk of diabetic complications. The ACE polymorphism does not significantly affect blood pressure or angiotensin II levels, suggesting that the kallikrein-kinin system partly mediates the effects of the polymorphism. We have therefore explored the influence of lack of both bradykinin receptors (B1R and B2R) on diabetic nephropathy, neuropathy, and osteopathy in male mice heterozygous for the Akita diabetogenic mutation in the insulin 2 gene (Ins2). We find that all of the detrimental phenotypes observed in Akita diabetes are enhanced by lack of both B1R and B2R, including urinary albumin excretion, glomerulosclerosis, glomerular basement membrane thickening, mitochondrial DNA deletions, reduction of nerve conduction velocities and of heat sensation, and bone mineral loss. Absence of the bradykinin receptors also enhances the diabetes-associated increases in plasma thiobarbituric acid-reactive substances, mitochondrial DNA deletions, and renal expression of fibrogenic genes, including transforming growth factor beta1, connective tissue growth factor, and endothelin-1. Thus, lack of B1R and B2R exacerbates diabetic complications. The enhanced renal injury in diabetic mice caused by lack of B1R and B2R may be mediated by a combination of increases in oxidative stress, mitochondrial DNA damage and over expression of fibrogenic genes.
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88
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Yokoi H, Kasahara M, Mukoyama M, Mori K, Kuwahara K, Fujikura J, Arai Y, Saito Y, Ogawa Y, Kuwabara T, Sugawara A, Nakao K. Podocyte-specific expression of tamoxifen-inducible Cre recombinase in mice. Nephrol Dial Transplant 2010; 25:2120-4. [PMID: 20150167 DOI: 10.1093/ndt/gfq029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Podocytes play an important role in maintaining normal glomerular function. A podocyte-specific conditional knockout technology has been established by the use of transgenic mice expressing a podocyte-specific Cre recombinase to clarify the role of genes expressed in the podocytes. However, it may be difficult to examine the role of genes in certain pathologic conditions using conventional podocyte-specific knockout mice because they may be embryonically lethal or exhibit congenital renal abnormality. METHODS To introduce a temporal control in the genetic experiments targeting the podocyte, we constructed tamoxifen-inducible Cre recombinase (CreER(T2)) transgenic mice under the control of podocyte-specific promoter, 2.5-kb fragment of the human podocin (NPHS2) gene. The specificity and efficiency of Cre activity were examined by crossing NPHS2-CreER(T2) with the ROSA26 reporter (R26R) mouse in which a floxed-stop cassette has been placed upstream of the beta-galactosidase gene. Four-week-old double-mutant mice (NPHS2-CreER(T2)/R26R) were intraperitoneally administered with 0.5 mg of 4-hydroxytamoxifen (4-OHT) for three consecutive days. RESULTS NPHS2-CreER(T2)/R26R treated with 4-OHT expressed beta-galactosidase specifically in 85% of the podocytes in glomeruli. Expression of Cre recombinase mRNA was mostly restricted to the kidney, especially in glomeruli. CONCLUSIONS In conclusion, we have successfully generated podocyte-specific inducible Cre transgenic mice by tamoxifen administration. These mice allow us to disrupt the genes specifically in the podocytes after birth.
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Affiliation(s)
- Hideki Yokoi
- Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, Kyoto, Kyoto, Japan
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89
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Ohtomo S, Izuhara Y, Nangaku M, Dan T, Ito S, van Ypersele de Strihou C, Miyata T. Body weight control by a high-carbohydrate/low-fat diet slows the progression of diabetic kidney damage in an obese, hypertensive, type 2 diabetic rat model. J Obes 2010; 2010:136502. [PMID: 20700413 PMCID: PMC2911582 DOI: 10.1155/2010/136502] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Revised: 10/07/2009] [Accepted: 11/16/2009] [Indexed: 01/09/2023] Open
Abstract
Obesity is one of several factors implicated in the genesis of diabetic nephropathy (DN). Obese, hypertensive, type 2 diabetic rats SHR/NDmcr-cp were given, for 12 weeks, either a normal, middle-carbohydrate/middle-fat diet (MC/MF group) or a high-carbohydrate/low-fat diet (HC/LF group). Daily caloric intake was the same in both groups. Nevertheless, the HC/LF group gained less weight. Despite equivalent degrees of hypertension, hyperglycemia, hyperlipidemia, hyperinsulinemia, and even a poorer glycemic control, the HC/LF group had less severe renal histological abnormalities and a reduced intrarenal advanced glycation and oxidative stress. Mediators of the renoprotection, specifically linked to obesity and body weight control, include a reduced renal inflammation and TGF-beta expression, together with an enhanced level of adiponectin. Altogether, these data identify a specific role of body weight control by a high-carbohydrate/low-fat diet in the progression of DN. Body weight control thus impacts on local intrarenal advanced glycation and oxidative stress through inflammation and adiponectin levels.
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Affiliation(s)
- Shuichi Ohtomo
- Research Division, Chugai Pharmaceutical Co., LTD., Shizuoka 412-8513, Japan
- Institute of Medical Sciences, Tokai University, Kanagawa 259-1193, Japan
- *Shuichi Ohtomo:
| | - Yuko Izuhara
- Institute of Medical Sciences, Tokai University, Kanagawa 259-1193, Japan
| | - Masaomi Nangaku
- Division of Nephrology and Endocrinology, University of Tokyo School of Medicine, Tokyo 113-8655, Japan
| | - Takashi Dan
- Center for Translational and Advanced Research, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | - Sadayoshi Ito
- Department of Nephrology, Hypertension and Endocrinology, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
| | | | - Toshio Miyata
- Center for Translational and Advanced Research, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan
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Mizutani M, Ito Y, Mizuno M, Nishimura H, Suzuki Y, Hattori R, Matsukawa Y, Imai M, Oliver N, Goldschmeding R, Aten J, Krediet RT, Yuzawa Y, Matsuo S. Connective tissue growth factor (CTGF/CCN2) is increased in peritoneal dialysis patients with high peritoneal solute transport rate. Am J Physiol Renal Physiol 2009; 298:F721-33. [PMID: 20015945 DOI: 10.1152/ajprenal.00368.2009] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Peritoneal fibrosis (PF) is an important complication of peritoneal dialysis (PD) therapy that often occurs in association with peritoneal high transport rate and ultrafiltration failure (UFF). To study the possible pathogenic role of connective tissue growth factor (CTGF) in the relationship of PF and UFF, dialysate CTGF contents (n = 178) and tissue CTGF expression (n = 61) were investigated by ELISA, real-time PCR, immunohistochemistry, and in situ hybridization. CTGF production with and without TGF-beta1 stimulation in human peritoneal mesothelial cells (HPMC) from the spent patients' peritoneal dialysate (n = 32) was studied in vitro. The dialysate-to-plasma ratio for creatinine (D/P Cr) was positively correlated to dialysate CTGF concentration and estimated local peritoneal production of CTGF. CTGF mRNA expression was 11.4-fold higher in peritoneal membranes with UFF than in pre-PD renal failure peritoneum and was correlated with thickness of the peritoneum. CTGF protein and mRNA were detected in mesothelium and in fibroblast-like cells. In cultured HPMC, TGF-beta(1)-induced expression of CTGF mRNA was increased at 12 and 24 h and was correlated with D/P Cr. In contrast, bone morphogenic protein-4 mRNA expression was inversely correlated with D/P Cr. Our results suggest that high peritoneal transport state is associated with fibrosis and increased peritoneal CTGF expression and production by mesothelial cells, which can be stimulated by TGF-beta1. Dialysate CTGF concentration could be a biomarker for both peritoneal fibrosis and membrane function. Functional alteration of mesothelial cells may be involved in progression of peritoneal fibrosis in high transport state.
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Affiliation(s)
- Makoto Mizutani
- Department of Nephrology and Renal Replacement Therapy, Nagoya University Graduate School of Medicine, Nagoya, Japan
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91
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Chung ACK, Zhang H, Kong YZ, Tan JJ, Huang XR, Kopp JB, Lan HY. Advanced glycation end-products induce tubular CTGF via TGF-beta-independent Smad3 signaling. J Am Soc Nephrol 2009; 21:249-60. [PMID: 19959709 DOI: 10.1681/asn.2009010018] [Citation(s) in RCA: 156] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Advanced glycation end-products (AGEs) can induce expression of connective tissue growth factor (CTGF), which seems to promote the development of diabetic nephropathy, but the exact signaling mechanisms that mediate this induction are unknown. Here, AGEs induced CTGF expression in tubular epithelial cells (TECs) that either lacked the TGF-beta1 gene or expressed dominant TGF-beta receptor II, demonstrating independence of TGF-beta. Furthermore, conditional knockout of the gene encoding TGF-beta receptor II from the kidney did not prevent AGE-induced renal expression of CTGF and collagen I. More specific, AGEs induced CTGF expression via the receptor for AGEs-extracellular signal-regulated kinase (RAGE-ERK)/p38 mitogen-activated protein kinase-Smad cross-talk pathway because inhibition of this pathway by several methods (anti-RAGE antibody, specific inhibitors, or dominant negative adenovirus to ERK1/2 and p38) blocked this induction. Overexpressing Smad7 abolished AGE-induced Smad3 phosphorylation and CTGF expression, demonstrating the necessity for activation of Smad signaling in this process. More important, knockdown of either Smad3 or Smad2 demonstrated that Smad3 but not Smad2 is essential for CTGF induction in response to AGEs. In conclusion, AGEs induce tubular CTGF expression via the TGF-beta-independent RAGE-ERK/p38-Smad3 cross-talk pathway. These data suggest that overexpression of Smad7 or targeting Smad3 may have therapeutic potential for diabetic nephropathy.
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Affiliation(s)
- Arthur C K Chung
- Department of Medicine and Therapeutics, and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong, China
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92
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Connective tissue growth factor (CCN2, CTGF) and organ fibrosis: lessons from transgenic animals. J Cell Commun Signal 2009; 4:1-4. [PMID: 19798591 PMCID: PMC2821473 DOI: 10.1007/s12079-009-0071-5] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Accepted: 09/13/2009] [Indexed: 12/20/2022] Open
Abstract
In recent months, four different systems have been reported in the literature in which CCN2 transgenes were individually expressed in podocytes, hepatocytes, cardiomyocytes or respiratory epithelial cells to achieve overexpression in, respectively, the kidney, liver, heart, or lung. These transgenic systems have provided valuable information about the contribution of CCN2 to fibrosis in vivo and have begun to reveal the complexities of the underlying mechanisms involved. On the one hand, studies of these animals have revealed that CCN2 overexpression does not necessarily lead directly to fibrotic pathology but may cause severe non-fibrotic tissue damage due to its other effects on cell function (e.g. heart). On the other hand, overexpression of CCN2 in concert with signaling pathways associated with development (e.g. lung) or fibrosing injuries (e.g. kidney, liver) can lead to the initiation or exacerbation of fibrosis. The significance of these studies is discussed in the context of the requirement for interactions between CCN2 and co-stimulatory factors in the microenvironment for the manifestation of CCN2-dependent fibrosis.
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93
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Tong Z, Chen R, Alt DS, Kemper S, Perbal B, Brigstock DR. Susceptibility to liver fibrosis in mice expressing a connective tissue growth factor transgene in hepatocytes. Hepatology 2009; 50:939-47. [PMID: 19670427 PMCID: PMC2737071 DOI: 10.1002/hep.23102] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
UNLABELLED Connective tissue growth factor (CCN2) is a matricellular protein that is up-regulated in many fibrotic disorders and coexpressed with transforming growth factor beta. CCN2 promotes fibrogenesis and survival in activated hepatic stellate cells, and injured or fibrotic liver contains up-regulated levels of CCN2 that are produced by a variety of different cell types, including hepatocytes. To investigate CCN2 action in vivo, transgenic FVB mice were created in which the human CCN2 gene was placed under the control of the albumin enhancer promoter to elevate hepatocyte CCN2 levels. Production of human CCN2 (hCCN2) messenger RNA and elevated CCN2 protein levels was demonstrated in transgenic livers, whereas levels of endogenous mouse CCN2 were comparable between transgenic and wild-type mice. Liver histology and liver function tests were unaffected in transgenic animals. However, after chronic administration of CCl(4), alpha-smooth muscle actin (alpha-SMA)-expressing cells and collagen deposition were increased as a function of the dosage of the hCCN2 transgene (hccn2(+/+) > hccn2(+/-) > hccn2(-/-)). Moreover, CCl(4)-induced serum hyaluronic acid, hepatic tissue levels of alpha-SMA or acid-soluble collagen, and messenger RNA expression of alpha-SMA, collagen alpha1 (I), matrix metalloprotease-2, or tissue inhibitor of metalloprotease-1 were greater in transgenic mice than in wild-type mice. Transgenic mice also exhibited enhanced hepatic deposition of collagen 2 weeks after bile duct ligation. CONCLUSION Production of elevated CCN2 levels in hepatocytes of transgenic mice in vivo does not cause hepatic injury or fibrosis per se but renders the livers more susceptible to the injurious actions of other fibrotic stimuli. These studies support a central role of CCN2 in hepatic fibrosis and demonstrate a role of the microenvironment in regulating the profibrotic action of CCN2.
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Affiliation(s)
- ZhenYue Tong
- Center for Cell and Developmental Biology, The Research Institute at Nationwide Children's Hospital, Columbus Ohio 43205 USA
| | - Ruju Chen
- Center for Cell and Developmental Biology, The Research Institute at Nationwide Children's Hospital, Columbus Ohio 43205 USA
| | - Daniel S Alt
- Center for Cell and Developmental Biology, The Research Institute at Nationwide Children's Hospital, Columbus Ohio 43205 USA
| | - Sherri Kemper
- Center for Cell and Developmental Biology, The Research Institute at Nationwide Children's Hospital, Columbus Ohio 43205 USA
| | - Bernard Perbal
- Laboratoire d'Oncologie, Virale et Moléculaire, UFR de Biochimie, Université Paris 7-D. Diderot, 2 Place Jussieu 75 005, Paris, France
| | - David R Brigstock
- Center for Cell and Developmental Biology, The Research Institute at Nationwide Children's Hospital, Columbus Ohio 43205 USA, Departments of Surgery and Molecular and Cellular Biochemistry, The Ohio State University, Columbus OH 43205 USA
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Panek AN, Posch MG, Alenina N, Ghadge SK, Erdmann B, Popova E, Perrot A, Geier C, Morano RDI, Bader M, Özcelik C. Connective tissue growth factor overexpression in cardiomyocytes promotes cardiac hypertrophy and protection against pressure overload. PLoS One 2009; 4:e6743. [PMID: 19707545 PMCID: PMC2727794 DOI: 10.1371/journal.pone.0006743] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Accepted: 07/27/2009] [Indexed: 11/29/2022] Open
Abstract
Connective tissue growth factor (CTGF) is a secreted protein that is strongly induced in human and experimental heart failure. CTGF is said to be profibrotic; however, the precise function of CTGF is unclear. We generated transgenic mice and rats with cardiomyocyte-specific CTGF overexpression (CTGF-TG). To investigate CTGF as a fibrosis inducer, we performed morphological and gene expression analyses of CTGF-TG mice and rat hearts under basal conditions and after stimulation with angiotensin II (Ang II) or isoproterenol, respectively. Surprisingly, cardiac tissues of both models did not show increased fibrosis or enhanced gene expression of fibrotic markers. In contrast to controls, Ang II treated CTGF-TG mice displayed preserved cardiac function. However, CTGF-TG mice developed age-dependent cardiac dysfunction at the age of 7 months. CTGF related heart failure was associated with Akt and JNK activation, but not with the induction of natriuretic peptides. Furthermore, cardiomyocytes from CTGF-TG mice showed unaffected cellular contractility and an increased Ca2+ reuptake from sarcoplasmatic reticulum. In an ischemia/reperfusion model CTGF-TG hearts did not differ from controls. Our data suggest that CTGF itself does not induce cardiac fibrosis. Moreover, it is involved in hypertrophy induction and cellular remodeling depending on the cardiac stress stimulus. Our new transgenic animals are valuable models for reconsideration of CTGF's profibrotic function in the heart.
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Affiliation(s)
- Anna N. Panek
- Department of Cardiovascular and Metabolic Disease Research, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Maximilian G. Posch
- Experimental and Clinical Research Center (ECRC) at the Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Department of Cardiology, Charité-Universitätsmedizin, Campus Virchow Klinikum, Berlin, Germany
| | - Natalia Alenina
- Department of Cardiovascular and Metabolic Disease Research, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Santhosh K. Ghadge
- Department of Cardiovascular and Metabolic Disease Research, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Bettina Erdmann
- Department of Cardiovascular and Metabolic Disease Research, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Elena Popova
- Department of Cardiovascular and Metabolic Disease Research, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Andreas Perrot
- Experimental and Clinical Research Center (ECRC) at the Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Department of Cardiology, Charité-Universitätsmedizin, Campus Virchow Klinikum, Berlin, Germany
| | - Christian Geier
- Experimental and Clinical Research Center (ECRC) at the Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Department of Cardiology, Charité-Universitätsmedizin, Campus Virchow Klinikum, Berlin, Germany
| | - Rainer Dietz Ingo Morano
- Department of Cardiovascular and Metabolic Disease Research, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Experimental and Clinical Research Center (ECRC) at the Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Department of Cardiology, Charité-Universitätsmedizin, Campus Virchow Klinikum, Berlin, Germany
| | - Michael Bader
- Department of Cardiovascular and Metabolic Disease Research, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Cemil Özcelik
- Department of Cardiovascular and Metabolic Disease Research, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Experimental and Clinical Research Center (ECRC) at the Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Department of Cardiology, Charité-Universitätsmedizin, Campus Virchow Klinikum, Berlin, Germany
- * E-mail:
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95
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Yang F, Chung ACK, Huang XR, Lan HY. Angiotensin II induces connective tissue growth factor and collagen I expression via transforming growth factor-beta-dependent and -independent Smad pathways: the role of Smad3. Hypertension 2009; 54:877-84. [PMID: 19667256 DOI: 10.1161/hypertensionaha.109.136531] [Citation(s) in RCA: 206] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Connective tissue growth factor (CTGF) plays a critical role in angiotensin II (Ang II)-mediated hypertensive nephropathy. The present study investigated the mechanisms and specific roles of individual Smads in Ang II-induced CTGF and collagen I expression in tubular epithelial cells with deletion of transforming growth factor (TGF)-beta1, overexpression of Smad7, or knockdown of Smad2 or Smad3. We found that Ang II-induced tubular CTGF and collagen I mRNA and protein expressions were regulated positively by phosphorylated Smad2/3 but negatively by Smad7 because overexpression of Smad7-abolished Ang II-induced Smad2/3 phosphorylation and upregulation of CTGF and collagen I in vitro and in a rat model of remnant kidney disease. Additional studies revealed that, in addition to a late (24-hour) TGF-beta-dependent Smad2/3 activation, Ang II also induced a rapid activation of Smad2/3 at 15 minutes and expression of CTGF and collagen I in tubular epithelial cells lacking the TGF-beta gene, which was blocked by the addition of an Ang II type 1 receptor antagonist (losartan) and inhibitors to extracellular signal-regulated kinase 1/2 (PD98059) and p38 (SB203580) but not by inhibitors to Ang II type 2 receptor (PD123319) or c-Jun N-terminal kinase (SP600125), demonstrating a TGF-beta-independent, Ang II type 1 receptor-mediated extracellular signal-regulated kinase/p38 mitogen-activated protein kinase cross-talk pathway in Ang II-mediated CTGF and collagen I expression. Importantly, the ability of knockdown of Smad3, but not Smad2, to inhibit Ang II-induced CTGF and collagen I expression further revealed an essential role for Smad3 in Ang II-mediated renal fibrosis. In conclusion, Ang II induces tubular CTGF expression and renal fibrosis via the TGF-beta-dependent and -independent Smad3 signaling pathways, suggesting that targeting Smad3 may have therapeutic potential for hypertensive nephropathy.
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Affiliation(s)
- Fuye Yang
- Department of Medicine and Therapeutic, and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT, Hong Kong, China
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96
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Turk T, Leeuwis JW, Gray J, Torti SV, Lyons KM, Nguyen TQ, Goldschmeding R. BMP signaling and podocyte markers are decreased in human diabetic nephropathy in association with CTGF overexpression. J Histochem Cytochem 2009; 57:623-31. [PMID: 19255250 DOI: 10.1369/jhc.2009.953224] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Diabetic nephropathy is characterized by decreased expression of bone morphogenetic protein-7 (BMP-7) and decreased podocyte number and differentiation. Extracellular antagonists such as connective tissue growth factor (CTGF; CCN-2) and sclerostin domain-containing-1 (SOSTDC1; USAG-1) are important determinants of BMP signaling activity in glomeruli. We studied BMP signaling activity in glomeruli from diabetic patients and non-diabetic individuals and from control and diabetic CTGF(+/+) and CTGF(+/-) mice. BMP signaling activity was visualized by phosphorylated Smad1, -5, and -8 (pSmad1/5/8) immunostaining, and related to expression of CTGF, SOSTDC1, and the podocyte differentiation markers WT1, synaptopodin, and nephrin. In control and diabetic glomeruli, pSmad1/5/8 was mainly localized in podocytes, but both number of positive cells and staining intensity were decreased in diabetes. Nephrin and synaptopodin were decreased in diabetic glomeruli. Decrease of pSmad1/5/8 was only partially explained by decrease in podocyte number. SOSTDC1 and CTGF were expressed exclusively in podocytes. In diabetic glomeruli, SOSTDC1 decreased in parallel with podocyte number, whereas CTGF was strongly increased. In diabetic CTGF(+/-) mice, pSmad1/5/8 was preserved, compared with diabetic CTGF(+/+) mice. In conclusion, in human diabetic nephropathy, BMP signaling activity is diminished, together with reduction of podocyte markers. This might relate to concomitant overexpression of CTGF but not SOSTDC1.
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Affiliation(s)
- Tamara Turk
- Department of Pathology, H04.312, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
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97
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Brigstock DR. Strategies for blocking the fibrogenic actions of connective tissue growth factor (CCN2): From pharmacological inhibition in vitro to targeted siRNA therapy in vivo. J Cell Commun Signal 2009; 3:5-18. [PMID: 19294531 PMCID: PMC2686750 DOI: 10.1007/s12079-009-0043-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Accepted: 02/28/2009] [Indexed: 01/07/2023] Open
Abstract
Connective tissue growth factor (CCN2) is a major pro-fibrotic factor that frequently acts downstream of transforming growth factor beta (TGF-beta)-mediated fibrogenic pathways. Much of our knowledge of CCN2 in fibrosis has come from studies in which its production or activity have been experimentally attenuated. These studies, performed both in vitro and in animal models, have demonstrated the utility of pharmacological inhibitors (e.g. tumor necrosis factor alpha (TNF-alpha), prostaglandins, peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists, statins, kinase inhibitors), neutralizing antibodies, antisense oligonucleotides, or small interfering RNA (siRNA) to probe the role of CCN2 in fibrogenic pathways. These investigations have allowed the mechanisms regulating CCN2 production to be more clearly defined, have shown that CCN2 is a rational anti-fibrotic target, and have established a framework for developing effective modalities of therapeutic intervention in vivo.
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Affiliation(s)
- David R Brigstock
- The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA,
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98
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Mason RM. Connective tissue growth factor(CCN2), a pathogenic factor in diabetic nephropathy. What does it do? How does it do it? J Cell Commun Signal 2009; 3:95-104. [PMID: 19214781 PMCID: PMC2721079 DOI: 10.1007/s12079-009-0038-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Accepted: 01/26/2009] [Indexed: 01/15/2023] Open
Abstract
Connective tissue growth factor (CTGF/CCN2) is a member of the CCN family of matricellular proteins. Its expression is induced by a number of factors including TGF-β. It has been associated with fibrosis in various tissues including the kidney. Diabetic nephropathy (DN) develops in about 30% of patients with diabetes and is characterized by thickening of renal basement membranes, fibrosis in the glomerulus (glomerulosclerosis), tubular atrophy and interstitial fibrosis, all of which compromise kidney function. This review examines changes in CTGF expression in the kidney in DN, the effects they have on glomerular mesangial and podocyte cells and the tubulointerstitium, and how these contribute to driving fibrotic changes in the disease. CTGF can bind to several other growth factors modifying their function. CTGF is also able to interact with receptors on cells, including integrins, tyrosine receptor kinase A (TrkA), low density lipoprotein receptor-related protein (LRP) and heparan sulphate proteoglycans. These interactions, the intracellular signalling pathways they activate, and the cellular responses evoked are reviewed. CTGF also induces the expression of chemokines which themselves have pharmacological actions on cells. CTGF may prompt some responses by acting through several different mechanisms, possibly simultaneously. For example, CTGF is often described as an effector of TGF-β. It can promote TGF-β signalling by binding directly to the growth factor, promoting its interaction with the TGF-β receptor; by triggering intracellular signalling on binding the TrkA receptor, which leads to the transcriptional repression of Smad7, an inhibitor of the TGF-β signalling pathway; and by binding to BMP-7 whose own signalling pathway opposing TGF-β is inhibited, leading to enhanced TGF-β signalling.
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Affiliation(s)
- Roger M Mason
- Division of Medicine, Imperial College London, London, W12 ONN, UK,
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Urinary neutrophil gelatinase-associated lipocalin levels reflect damage to glomeruli, proximal tubules, and distal nephrons. Kidney Int 2008; 75:285-94. [PMID: 19148153 DOI: 10.1038/ki.2008.499] [Citation(s) in RCA: 215] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Urinary neutrophil gelatinase-associated lipocalin (Ngal or lipocalin 2) is a very early and sensitive biomarker of kidney injury. Here we determined the origin and time course of Ngal appearance in several experimental and clinically relevant renal diseases. Urinary Ngal levels were found to be markedly increased in lipoatrophic- and streptozotocin-induced mouse models of diabetic nephropathy. In the latter mice, the angiotensin receptor blocker candesartan dramatically decreased urinary Ngal excretion. The reabsorption of Ngal by the proximal tubule was severely reduced in streptozotocin-induced diabetic mice, but upregulation of its mRNA and protein in the kidney was negligible, compared to those of control mice, suggesting that increased urinary Ngal was mainly due to impaired renal reabsorption. In the mouse model of unilateral ureteral obstruction, Ngal protein synthesis was dramatically increased in the dilated thick ascending limb of Henle and N was found in the urine present in the swollen pelvis of the ligated kidney. Five patients with nephrotic syndrome or interstitial nephritis had markedly elevated urinary Ngal levels at presentation, but these decreased in response to treatment. Our study shows that the urinary Ngal level may be useful for monitoring the status and treatment of diverse renal diseases reflecting defects in glomerular filtration barrier, proximal tubule reabsorption, and distal nephrons.
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