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Staruschenko A, Ma R, Palygin O, Dryer SE. Ion channels and channelopathies in glomeruli. Physiol Rev 2023; 103:787-854. [PMID: 36007181 PMCID: PMC9662803 DOI: 10.1152/physrev.00013.2022] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/15/2022] [Accepted: 08/21/2022] [Indexed: 11/22/2022] Open
Abstract
An essential step in renal function entails the formation of an ultrafiltrate that is delivered to the renal tubules for subsequent processing. This process, known as glomerular filtration, is controlled by intrinsic regulatory systems and by paracrine, neuronal, and endocrine signals that converge onto glomerular cells. In addition, the characteristics of glomerular fluid flow, such as the glomerular filtration rate and the glomerular filtration fraction, play an important role in determining blood flow to the rest of the kidney. Consequently, disease processes that initially affect glomeruli are the most likely to lead to end-stage kidney failure. The cells that comprise the glomerular filter, especially podocytes and mesangial cells, express many different types of ion channels that regulate intrinsic aspects of cell function and cellular responses to the local environment, such as changes in glomerular capillary pressure. Dysregulation of glomerular ion channels, such as changes in TRPC6, can lead to devastating glomerular diseases, and a number of channels, including TRPC6, TRPC5, and various ionotropic receptors, are promising targets for drug development. This review discusses glomerular structure and glomerular disease processes. It also describes the types of plasma membrane ion channels that have been identified in glomerular cells, the physiological and pathophysiological contexts in which they operate, and the pathways by which they are regulated and dysregulated. The contributions of these channels to glomerular disease processes, such as focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, as well as the development of drugs that target these channels are also discussed.
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Affiliation(s)
- Alexander Staruschenko
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida
- Hypertension and Kidney Research Center, University of South Florida, Tampa, Florida
- James A. Haley Veterans Hospital, Tampa, Florida
| | - Rong Ma
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Oleg Palygin
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, Texas
- Department of Biomedical Sciences, Tilman J. Fertitta Family College of Medicine, University of Houston, Houston, Texas
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Da Vitoria Lobo ME, Weir N, Hardowar L, Al Ojaimi Y, Madden R, Gibson A, Bestall SM, Hirashima M, Schaffer CB, Donaldson LF, Bates DO, Hulse RP. Hypoxia-induced carbonic anhydrase mediated dorsal horn neuron activation and induction of neuropathic pain. Pain 2022; 163:2264-2279. [PMID: 35353768 PMCID: PMC9578530 DOI: 10.1097/j.pain.0000000000002627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 02/17/2022] [Accepted: 02/23/2022] [Indexed: 11/27/2022]
Abstract
ABSTRACT Neuropathic pain, such as that seen in diabetes mellitus, results in part from central sensitisation in the dorsal horn. However, the mechanisms responsible for such sensitisation remain unclear. There is evidence that disturbances in the integrity of the spinal vascular network can be causative factors in the development of neuropathic pain. Here we show that reduced blood flow and vascularity of the dorsal horn leads to the onset of neuropathic pain. Using rodent models (type 1 diabetes and an inducible endothelial-specific vascular endothelial growth factor receptor 2 knockout mouse) that result in degeneration of the endothelium in the dorsal horn, we show that spinal cord vasculopathy results in nociceptive behavioural hypersensitivity. This also results in increased hypoxia in dorsal horn neurons, depicted by increased expression of hypoxia markers such as hypoxia inducible factor 1α, glucose transporter 3, and carbonic anhydrase 7. Furthermore, inducing hypoxia through intrathecal delivery of dimethyloxalylglycine leads to the activation of dorsal horn neurons as well as mechanical and thermal hypersensitivity. This shows that hypoxic signalling induced by reduced vascularity results in increased hypersensitivity and pain. Inhibition of carbonic anhydrase activity, through intraperitoneal injection of acetazolamide, inhibited hypoxia-induced pain behaviours. This investigation demonstrates that induction of a hypoxic microenvironment in the dorsal horn, as occurs in diabetes, is an integral process by which neurons are activated to initiate neuropathic pain states. This leads to the conjecture that reversing hypoxia by improving spinal cord microvascular blood flow could reverse or prevent neuropathic pain.
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Affiliation(s)
- Marlene E. Da Vitoria Lobo
- Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Nick Weir
- School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom
| | - Lydia Hardowar
- School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom
| | - Yara Al Ojaimi
- School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom
| | - Ryan Madden
- Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Alex Gibson
- Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
| | - Samuel M. Bestall
- Pain Centre Versus Arthritis and School of Life Sciences, The Medical School QMC, University of Nottingham, Nottingham, United Kingdom
| | - Masanori Hirashima
- Division of Pharmacology, Niigata University Graduate School of Medical and Dental Sciences, Japan
| | - Chris B. Schaffer
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, United States
| | - Lucy F. Donaldson
- Pain Centre Versus Arthritis and School of Life Sciences, The Medical School QMC, University of Nottingham, Nottingham, United Kingdom
| | - David O. Bates
- Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane and Protein and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, United Kingdom
| | - Richard Philip Hulse
- Division of Cancer and Stem Cells, School of Medicine, Biodiscovery Institute, University of Nottingham, Nottingham, United Kingdom
- School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom
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Finch NC, Fawaz SS, Neal CR, Butler MJ, Lee VK, Salmon AJ, Lay AC, Stevens M, Dayalan L, Band H, Mellor HH, Harper SJ, Shima DT, Welsh GI, Foster RR, Satchell SC. Reduced Glomerular Filtration in Diabetes Is Attributable to Loss of Density and Increased Resistance of Glomerular Endothelial Cell Fenestrations. J Am Soc Nephrol 2022; 33:1120-1136. [PMID: 35292439 PMCID: PMC9161794 DOI: 10.1681/asn.2021030294] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 03/01/2022] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Glomerular endothelial cell (GEnC) fenestrations are recognized as an essential component of the glomerular filtration barrier, yet little is known about how they are regulated and their role in disease. METHODS We comprehensively characterized GEnC fenestral and functional renal filtration changes including measurement of glomerular Kf and GFR in diabetic mice (BTBR ob-/ob- ). We also examined and compared human samples. We evaluated Eps homology domain protein-3 (EHD3) and its association with GEnC fenestrations in diabetes in disease samples and further explored its role as a potential regulator of fenestrations in an in vitro model of fenestration formation using b.End5 cells. RESULTS Loss of GEnC fenestration density was associated with decreased filtration function in diabetic nephropathy. We identified increased diaphragmed fenestrations in diabetes, which are posited to increase resistance to filtration and further contribute to decreased GFR. We identified decreased glomerular EHD3 expression in diabetes, which was significantly correlated with decreased fenestration density. Reduced fenestrations in EHD3 knockdown b.End5 cells in vitro further suggested a mechanistic role for EHD3 in fenestration formation. CONCLUSIONS This study demonstrates the critical role of GEnC fenestrations in renal filtration function and suggests EHD3 may be a key regulator, loss of which may contribute to declining glomerular filtration function through aberrant GEnC fenestration regulation. This points to EHD3 as a novel therapeutic target to restore filtration function in disease.
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Affiliation(s)
- Natalie C. Finch
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Sarah S. Fawaz
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Chris R. Neal
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Matthew J. Butler
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Vivian K. Lee
- Translational Vision Research, Institute of Ophthalmology, University College London, London, United Kingdom
| | - Andrew J. Salmon
- Renal Service, Waitemata District Health Board, Auckland, New Zealand
| | - Abigail C. Lay
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Megan Stevens
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom
| | - Lusyan Dayalan
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Hamid Band
- Eppley Institute for Research in Cancer, and Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska
| | - Harry H. Mellor
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Steven J. Harper
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - David T. Shima
- Translational Vision Research, Institute of Ophthalmology, University College London, London, United Kingdom
| | - Gavin I. Welsh
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Rebecca R. Foster
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Simon C. Satchell
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, United Kingdom
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Suramin enhances the urinary excretion of VEGF-A in normoglycemic and streptozotocin-induced diabetic rats. Pharmacol Rep 2021; 73:841-846. [PMID: 33635529 PMCID: PMC8180480 DOI: 10.1007/s43440-021-00236-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/11/2021] [Accepted: 02/13/2021] [Indexed: 10/24/2022]
Abstract
BACKGROUND Vascular endothelial growth factor A (VEGF-A) and P2-receptors (P2Rs) are involved in the pathogenesis of diabetic nephropathy. The processing of VEGF-A by matrix metalloproteinases (MMP) regulates its bioavailability. Since the ATP-induced release of MMP-9 is mediated by P2Rs, we investigated the effect of suramin on VEGF-A excretion in urine and the urinary activity of total MMP and MMP-9. METHODS The effect of suramin (10 mg/kg, ip) on VEGF-A concentration in serum and its excretion in urine was investigated in streptozotocin (STZ)-induced diabetic rats over a 21-day period. The rats received suramin 7 and 14 days after a single STZ injection (65 mg/kg, ip). A 24-h collection of urine was performed on the day preceding the administration of STZ and the first administration of suramin and on the day before the end of the experiment. The VEGF-A in serum and urine, albumin in urine, and total activity of MMP and MMP-9 in urine were measured using immunoassays. RESULTS Diabetic rats are characterized by a sixfold higher urinary excretion of VEGF-A. Suramin potentiates VEGF-A urinary excretion by 36% (p = 0.046) in non-diabetic and by 75% (p = 0.0322) in diabetic rats but it did not affect VEGF-A concentration in the serum of non-diabetic and diabetic rats. Urinary albumin excretion as well as total MMP and MMP-9 activity was increased in diabetic rats, but these parameters were not affected by suramin. CONCLUSION Suramin increases the urinary excretion of VEGF-A in normoglycemia and hyperglycaemia, possibly without the involvement of MMP-9. Suramin may be used as a pharmacological tool enhancing VEGF-A urinary secretion.
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He M, Wang J, Yin Z, Zhao Y, Hou H, Fan J, Li H, Wen Z, Tang J, Wang Y, Wang DW, Chen C. MiR-320a induces diabetic nephropathy via inhibiting MafB. Aging (Albany NY) 2019; 11:3055-3079. [PMID: 31102503 PMCID: PMC6555468 DOI: 10.18632/aging.101962] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 05/06/2019] [Indexed: 12/17/2022]
Abstract
Multiple studies indicate that microRNAs (miRNAs) are involved in diabetes. However, the roles of miRNA in the target organ damages in diabetes remain unclear. This study investigated the functions of miR-320a in diabetic nephropathy (DN). In this study, db/db mice were used to observe the changes in podocytes and their function in vivo, as well as in cultured mouse podocyte cells (MPC5) exposed to high glucose in vitro. To further explore the role of miR-320a in DN, recombinant adeno-associated viral particle was administered intravenously to manipulate the expression of miR-320a in db/db mice. Overexpression of miR-320a markedly promoted podocyte loss and dysfunction in DN, including mesangial expansion and increased levels of proteinuria, serum creatinine and urea nitrogen. Furthermore, MafB was identified as a direct target of miR-320a through AGO2 co-immunoprecipitation, luciferase reporter assay, and Western blotting. Moreover, re-expression of MafB rescued miR-320a-induced podocyte loss and dysfunction by upregulating the expressions of Nephrin and glutathione peroxidase 3 (Gpx3). Our data indicated that miR-320a aggravated renal disfunction in DN by targeting MafB and downregulating Nephrin and Gpx3 in podocytes, which suggested that miR-320a could be a potential therapeutic target of diabetic nephropathy.
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Affiliation(s)
- Mengying He
- Division of Cardiology and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Jin Wang
- Division of Cardiology and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Zhongwei Yin
- Division of Cardiology and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yanru Zhao
- Division of Cardiology and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Huiying Hou
- Division of Cardiology and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Jiahui Fan
- Division of Cardiology and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Huaping Li
- Division of Cardiology and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Zheng Wen
- Division of Cardiology and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Jiarong Tang
- Division of Cardiology and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yan Wang
- Division of Cardiology and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Dao Wen Wang
- Division of Cardiology and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Chen Chen
- Division of Cardiology and Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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6
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Stevens M, Neal CR, Craciun EC, Dronca M, Harper SJ, Oltean S. The natural drug DIAVIT is protective in a type II mouse model of diabetic nephropathy. PLoS One 2019; 14:e0212910. [PMID: 30865689 PMCID: PMC6415805 DOI: 10.1371/journal.pone.0212910] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 02/10/2019] [Indexed: 02/06/2023] Open
Abstract
There is evidence to suggest that abnormal angiogenesis, inflammation, and fibrosis drive diabetic nephropathy (DN). However, there is no specific treatment to counteract these processes. We aimed to determine whether DIAVIT, a natural Vaccinium myrtillus (blueberry) and Hippophae Rhamnoides (sea buckthorn) extract, is protective in a model of type II DN. Diabetic db/db mice were administered DIAVIT in their drinking water for 14 weeks. We assessed the functional, structural, and ultra-structural phenotype of three experimental groups (lean+vehicle, db/db+vehicle, db/db+DIAVIT). We also investigated the angiogenic and fibrotic pathways involved in the mechanism of action of DIAVIT. Diabetic db/db mice developed hyperglycaemia, albuminuria, and an increased glomerular water permeability; the latter two were prevented by DIAVIT. db/db mice developed fibrotic glomeruli, endothelial insult, and glomerular ultra-structural changes, which were not present in DIAVIT-treated mice. Vascular endothelial growth factor A (VEGF-A) splicing was altered in the db/db kidney cortex, increasing the pro-angiogenic VEGF-A165 relative to the anti-angiogenic VEGF-A165b. This was partially prevented with DIAVIT treatment. Delphinidin, an anthocyanin abundant in DIAVIT, increased the VEGF-A165b expression relative to total VEGF-A165 in cultured podocytes through phosphorylation of the splice factor SRSF6. DIAVIT, in particular delphinidin, alters VEGF-A splicing in type II DN, rescuing the DN phenotype. This study highlights the therapeutic potential of natural drugs in DN through the manipulation of gene splicing and expression.
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Affiliation(s)
- Megan Stevens
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
- Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
- * E-mail: (MS); (SO)
| | - Christopher R. Neal
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
- Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
| | - Elena C. Craciun
- Department of Pharmaceutical Biochemistry and Clinical Laboratory, School of Pharmacy, University of Medicine and Pharmacy “Iuliu Hatieganu” Cluj-Napoca, Romania
| | - Maria Dronca
- Department of Medical Biochemistry, School of Medicine, University of Medicine and Pharmacy “Iuliu Hatieganu” Cluj-Napoca, Romania
| | - Steven J. Harper
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
- Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
| | - Sebastian Oltean
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
- Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
- * E-mail: (MS); (SO)
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7
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Kikuchi R, Stevens M, Harada K, Oltean S, Murohara T. Anti-angiogenic isoform of vascular endothelial growth factor-A in cardiovascular and renal disease. Adv Clin Chem 2019; 88:1-33. [PMID: 30612603 DOI: 10.1016/bs.acc.2018.10.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Accumulating evidence suggests that pathologic interactions between the heart and the kidney can contribute to the progressive dysfunction of both organs. Recently, there has been an increase in the prevalence of cardiovascular disease (CVD) and chronic kidney disease (CKD) due to increasing obesity rates. It has been reported that obesity causes various heart and renal disorders and appears to accelerate their progression. Vascular endothelial growth factor-A (VEGF-A) is a major regulator of angiogenesis and vessel permeability, and is associated with CVD and CKD. It is now recognized that alternative VEGF-A gene splicing generates VEGF-A isoforms that differ in their biological actions. Proximal splicing that includes an exon 8a sequence results in pro-angiogenic VEGF-A165a, whereas distal splicing inclusive of exon 8b yields the anti-angiogenic isoform of VEGF-A (VEGF-A165b). This review highlights several recent preclinical and clinical studies on the role of VEGF-A165b in CVD and CKD as a novel function of VEGF-A. This review also discusses potential therapeutic approaches of the use of VEGF-A in clinical settings as a potential circulating biomarker for CVD and CKD.
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Affiliation(s)
- Ryosuke Kikuchi
- Department of Medical Technique, Nagoya University Hospital, Nagoya, Japan.
| | - Megan Stevens
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom
| | - Kazuhiro Harada
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Sebastian Oltean
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom
| | - Toyoaki Murohara
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
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8
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Onions KL, Gamez M, Buckner NR, Baker SL, Betteridge KB, Desideri S, Dallyn BP, Ramnath RD, Neal CR, Farmer LK, Mathieson PW, Gnudi L, Alitalo K, Bates DO, Salmon AHJ, Welsh GI, Satchell SC, Foster RR. VEGFC Reduces Glomerular Albumin Permeability and Protects Against Alterations in VEGF Receptor Expression in Diabetic Nephropathy. Diabetes 2019; 68:172-187. [PMID: 30389746 DOI: 10.2337/db18-0045] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 10/19/2018] [Indexed: 11/13/2022]
Abstract
Elevated levels of vascular endothelial growth factor (VEGF) A are thought to cause glomerular endothelial cell (GEnC) dysfunction and albuminuria in diabetic nephropathy. We hypothesized that VEGFC could counteract these effects of VEGFA to protect the glomerular filtration barrier and reduce albuminuria. Isolated glomeruli were stimulated ex vivo with VEGFC, which reduced VEGFA- and type 2 diabetes-induced glomerular albumin solute permeability (Ps'alb). VEGFC had no detrimental effect on glomerular function in vivo when overexpression was induced locally in podocytes (podVEGFC) in otherwise healthy mice. Further, these mice had reduced glomerular VEGFA mRNA expression, yet increased glomerular VEGF receptor heterodimerization, indicating differential signaling by VEGFC. In a model of type 1 diabetes, the induction of podVEGFC overexpression reduced the development of hypertrophy, albuminuria, loss of GEnC fenestrations and protected against altered VEGF receptor expression. In addition, VEGFC protected against raised Ps'alb by endothelial glycocalyx disruption in glomeruli. In summary, VEGFC reduced the development of diabetic nephropathy, prevented VEGF receptor alterations in the diabetic glomerulus, and promoted both glomerular protection and endothelial barrier function. These important findings highlight a novel pathway for future investigation in the treatment of diabetic nephropathy.
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Affiliation(s)
- Karen L Onions
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Monica Gamez
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Nicola R Buckner
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Siân L Baker
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Kai B Betteridge
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Sara Desideri
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Benjamin P Dallyn
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Raina D Ramnath
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Chris R Neal
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Louise K Farmer
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Peter W Mathieson
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Luigi Gnudi
- School of Cardiovascular Medicine and Science, British Heart Foundation Centre of Excellence, King's College London, London, U.K
| | - Kari Alitalo
- Wihuri Research Institute and Translational Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
| | - David O Bates
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, U.K
| | - Andrew H J Salmon
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Gavin I Welsh
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Simon C Satchell
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K
| | - Rebecca R Foster
- Bristol Renal, Bristol Heart Institute, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, U.K.
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9
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Abstract
The use of murine models to mimic human kidney disease is becoming increasingly common. Our research is focused on the assessment of glomerular function in diabetic nephropathy and podocyte-specific VEGF-A knock-out mice; therefore, this protocol describes the full kidney work-up used in our lab to assess these mouse models of glomerular disease, enabling a vast amount of information regarding kidney and glomerular function to be obtained from a single mouse. In comparison to alternative methods presented in the literature to assess glomerular function, the use of the method outlined in this paper enables the glomerular phenotype to be fully evaluated from multiple aspects. By using this method, the researcher can determine the kidney phenotype of the model and assess the mechanism as to why the phenotype develops. This vital information on the mechanism of disease is required when examining potential therapeutic avenues in these models. The methods allow for detailed functional assessment of the glomerular filtration barrier through measurement of the urinary albumin creatinine ratio and individual glomerular water permeability, as well as both structural and ultra-structural examination using the Periodic Acid Schiff stain and electron microscopy. Furthermore, analysis of the genes dysregulated at the mRNA and protein level enables mechanistic analysis of glomerular function. This protocol outlines the generic but adaptable methods that can be applied to all mouse models of glomerular disease.
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Affiliation(s)
- Megan Stevens
- Institute of Biomedical and Clinical Sciences, Medical School, University of Exeter; School of Physiology, Pharmacology and Neurosciences, University of Bristol; Bristol Renal, School of Clinical Sciences, University of Bristol;
| | - Sebastian Oltean
- Institute of Biomedical and Clinical Sciences, Medical School, University of Exeter; School of Physiology, Pharmacology and Neurosciences, University of Bristol; Bristol Renal, School of Clinical Sciences, University of Bristol;
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10
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Bates DO, Beazley-Long N, Benest AV, Ye X, Ved N, Hulse RP, Barratt S, Machado MJ, Donaldson LF, Harper SJ, Peiris-Pages M, Tortonese DJ, Oltean S, Foster RR. Physiological Role of Vascular Endothelial Growth Factors as Homeostatic Regulators. Compr Physiol 2018; 8:955-979. [PMID: 29978898 DOI: 10.1002/cphy.c170015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The vascular endothelial growth factor (VEGF) family of proteins are key regulators of physiological systems. Originally linked with endothelial function, they have since become understood to be principal regulators of multiple tissues, both through their actions on vascular cells, but also through direct actions on other tissue types, including epithelial cells, neurons, and the immune system. The complexity of the five members of the gene family in terms of their different splice isoforms, differential translation, and specific localizations have enabled tissues to use these potent signaling molecules to control how they function to maintain their environment. This homeostatic function of VEGFs has been less intensely studied than their involvement in disease processes, development, and reproduction, but they still play a substantial and significant role in healthy control of blood volume and pressure, interstitial volume and drainage, renal and lung function, immunity, and signal processing in the peripheral and central nervous system. The widespread expression of VEGFs in healthy adult tissues, and the disturbances seen when VEGF signaling is inhibited support this view of the proteins as endogenous regulators of normal physiological function. This review summarizes the evidence and recent breakthroughs in understanding of the physiology that is regulated by VEGF, with emphasis on the role they play in maintaining homeostasis. © 2017 American Physiological Society. Compr Physiol 8:955-979, 2018.
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Affiliation(s)
- David O Bates
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | | | - Andrew V Benest
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Xi Ye
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Nikita Ved
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Richard P Hulse
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Shaney Barratt
- Academic Respiratory Unit, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
| | - Maria J Machado
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Lucy F Donaldson
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Steven J Harper
- School of Physiology, Pharmacology & Neuroscience, Medical School, University of Bristol, Bristol, United Kingdom
| | - Maria Peiris-Pages
- Cancer Research UK Manchester Institute, The University of Manchester, Manchester, United Kingdom
| | - Domingo J Tortonese
- Centre for Comparative and Clinical Anatomy, University of Bristol, Bristol, United Kingdom
| | - Sebastian Oltean
- Institute of Biomedical & Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom
| | - Rebecca R Foster
- Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
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11
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Desideri S, Onions KL, Qiu Y, Ramnath RD, Butler MJ, Neal CR, King MLR, Salmon AE, Saleem MA, Welsh GI, Michel CC, Satchell SC, Salmon AHJ, Foster RR. A novel assay provides sensitive measurement of physiologically relevant changes in albumin permeability in isolated human and rodent glomeruli. Kidney Int 2018; 93:1086-1097. [PMID: 29433915 PMCID: PMC5912930 DOI: 10.1016/j.kint.2017.12.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 12/05/2017] [Accepted: 12/13/2017] [Indexed: 01/06/2023]
Abstract
Increased urinary albumin excretion is a key feature of glomerular disease but has limitations as a measure of glomerular permeability. Here we describe a novel assay to measure the apparent albumin permeability of single capillaries in glomeruli, isolated from perfused kidneys cleared of red blood cells. The rate of decline of the albumin concentration within the capillary lumen was quantified using confocal microscopy and used to calculate apparent permeability. The assay was extensively validated and provided robust, reproducible estimates of glomerular albumin permeability. These values were comparable with previous in vivo data, showing this assay could be applied to human as well as rodent glomeruli. To confirm this, we showed that targeted endothelial glycocalyx disruption resulted in increased glomerular albumin permeability in mice. Furthermore, incubation with plasma from patients with post-transplant recurrence of nephrotic syndrome increased albumin permeability in rat glomeruli compared to remission plasma. Finally, in glomeruli isolated from rats with early diabetes there was a significant increase in albumin permeability and loss of endothelial glycocalyx, both of which were ameliorated by angiopoietin-1. Thus, a glomerular permeability assay, producing physiologically relevant values with sufficient sensitivity to measure changes in glomerular permeability and independent of tubular function, was developed and validated. This assay significantly advances the ability to study biology and disease in rodent and human glomeruli.
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Affiliation(s)
- Sara Desideri
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Karen L Onions
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Yan Qiu
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Raina D Ramnath
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Matthew J Butler
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Christopher R Neal
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Matthew L R King
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Andrew E Salmon
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Moin A Saleem
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Gavin I Welsh
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | | | - Simon C Satchell
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Andrew H J Salmon
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Rebecca R Foster
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK.
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12
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Stevens M, Neal CR, Salmon AHJ, Bates DO, Harper SJ, Oltean S. Vascular Endothelial Growth Factor-A165b Restores Normal Glomerular Water Permeability in a Diphtheria-Toxin Mouse Model of Glomerular Injury. Nephron Clin Pract 2018; 139:51-62. [PMID: 29393270 DOI: 10.1159/000485664] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 11/24/2017] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND/AIMS Genetic cell ablation using the human diphtheria toxin receptor (hDTR) is a new strategy used for analysing cellular function. Diphtheria toxin (DT) is a cytotoxic protein that leaves mouse cells relatively unaffected, but upon binding to hDTR it ultimately leads to cell death. We used a podocyte-specific hDTR expressing (Pod-DTR) mouse to assess the anti-permeability and cyto-protective effects of the splice isoform vascular endothelial growth factor (VEGF-A165b). METHODS The Pod-DTR mouse was crossed with a mouse that over-expressed VEGF-A165b specifically in the podocytes (Neph-VEGF-A165b). Wild type (WT), Pod-DTR, Neph-VEGF-A165b and Pod-DTR X Neph-VEGF-A165b mice were treated with several doses of DT (1, 5, 100, and 1,000 ng/g bodyweight). Urine was collected and the glomerular water permeability (LpA/Vi) was measured ex vivo after 14 days. Structural analysis and podocyte marker expression were also assessed. RESULTS Pod-DTR mice developed an increased glomerular LpA/Vi 14 days after administration of DT (all doses), which was prevented when the mice over-expressed VEGF-A165b. No major structural abnormalities, podocyte ablation or albuminuria was observed in Pod-DTR mice, indicating this to be a mild model of podocyte disease. However, a change in expression and localisation of nephrin within the podocytes was observed, indicating disruption of the slit diaphragm in the Pod-DTR mice. This was prevented in the Pod-DTR X Neph-VEGF-A165b mice. CONCLUSION Although only a mild model of podocyte injury, over-expression of the anti-permeability VEGF-A165b isoform in the podocytes of Pod-DTR mice had a protective effect. Therefore, this study further highlights the therapeutic potential of VEGF-A165b in glomerular disease.
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Affiliation(s)
- Megan Stevens
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom.,School of Physiology, Pharmacology and Neurosciences, Bristol, United Kingdom.,Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
| | - Christopher R Neal
- School of Physiology, Pharmacology and Neurosciences, Bristol, United Kingdom.,Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
| | - Andrew H J Salmon
- School of Physiology, Pharmacology and Neurosciences, Bristol, United Kingdom.,Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
| | - David O Bates
- Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Steven J Harper
- School of Physiology, Pharmacology and Neurosciences, Bristol, United Kingdom.,Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
| | - Sebastian Oltean
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Exeter, United Kingdom.,School of Physiology, Pharmacology and Neurosciences, Bristol, United Kingdom.,Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, United Kingdom
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13
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Stevens M, Neal CR, Salmon AHJ, Bates DO, Harper SJ, Oltean S. VEGF-A 165 b protects against proteinuria in a mouse model with progressive depletion of all endogenous VEGF-A splice isoforms from the kidney. J Physiol 2017; 595:6281-6298. [PMID: 28574576 PMCID: PMC5621502 DOI: 10.1113/jp274481] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 05/17/2017] [Indexed: 01/25/2023] Open
Abstract
Key points Progressive depletion of all vascular endothelial growth factor A (VEGF‐A) splice isoforms from the kidney results in proteinuria and increased glomerular water permeability, which are both rescued by over‐expression of VEGF‐A165b only. VEGF‐A165b rescues the increase in glomerular basement membrane and podocyte slit width, as well as the decrease in sub‐podocyte space coverage, produced by VEGF‐A depletion. VEGF‐A165b restores the expression of platelet endothelial cell adhesion molecule in glomerular endothelial cells and glomerular capillary circumference. VEGF‐A165b has opposite effects to VEGF‐A165 on the expression of genes involved in endothelial cell migration and proliferation.
Abstract Chronic kidney disease is strongly associated with a decrease in the expression of vascular endothelial growth factor A (VEGF‐A). However, little is known about the contribution of VEGF‐A splice isoforms to kidney physiology and pathology. Previous studies suggest that the splice isoform VEGF‐A165b (resulting from alternative usage of a 3′ splice site in the terminal exon) is protective for kidney function. In the present study, we show, in a quad‐transgenic model, that over‐expression of VEGF‐A165b alone is sufficient to rescue the increase in proteinuria, as well as glomerular water permeability, in the context of progressive depletion of all VEGF‐A isoforms from the podocytes. Ultrastructural studies show that the glomerular basement membrane is thickened, podocyte slit width is increased and sub‐podocyte space coverage is reduced when VEGF‐A is depleted, all of which are rescued in VEGF‐A165b over‐expressors. VEGF‐A165b restores the expression of platelet endothelial cell adhesion molecule‐1 in glomerular endothelial cells and glomerular capillary circumference. Mechanistically, it increases VEGF receptor 2 expression both in vivo and in vitro and down‐regulates genes involved in migration and proliferation of endothelial cells, otherwise up‐regulated by the canonical isoform VEGF‐A165. The results of the present study indicate that manipulation of VEGF‐A splice isoforms could be a novel therapeutic avenue in chronic glomerular disease. Progressive depletion of all vascular endothelial growth factor A (VEGF‐A) splice isoforms from the kidney results in proteinuria and increased glomerular water permeability, which are both rescued by over‐expression of VEGF‐A165b only. VEGF‐A165b rescues the increase in glomerular basement membrane and podocyte slit width, as well as the decrease in sub‐podocyte space coverage, produced by VEGF‐A depletion. VEGF‐A165b restores the expression of platelet endothelial cell adhesion molecule in glomerular endothelial cells and glomerular capillary circumference. VEGF‐A165b has opposite effects to VEGF‐A165 on the expression of genes involved in endothelial cell migration and proliferation.
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Affiliation(s)
- Megan Stevens
- School of Physiology, Pharmacology and Neurosciences, University of Bristol, UK.,Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, UK.,Present address: Institute of Biomedical & Clinical Sciences, University of Exeter Medical School, Exeter, UK
| | - Christopher R Neal
- Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, UK
| | - Andrew H J Salmon
- School of Physiology, Pharmacology and Neurosciences, University of Bristol, UK.,Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, UK
| | - David O Bates
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham, UK
| | - Steven J Harper
- School of Physiology, Pharmacology and Neurosciences, University of Bristol, UK.,Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, UK
| | - Sebastian Oltean
- School of Physiology, Pharmacology and Neurosciences, University of Bristol, UK.,Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, UK.,Present address: Institute of Biomedical & Clinical Sciences, University of Exeter Medical School, Exeter, UK
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14
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Oltean S, Qiu Y, Ferguson JK, Stevens M, Neal C, Russell A, Kaura A, Arkill KP, Harris K, Symonds C, Lacey K, Wijeyaratne L, Gammons M, Wylie E, Hulse RP, Alsop C, Cope G, Damodaran G, Betteridge KB, Ramnath R, Satchell SC, Foster RR, Ballmer-Hofer K, Donaldson LF, Barratt J, Baelde HJ, Harper SJ, Bates DO, Salmon AHJ. Vascular Endothelial Growth Factor-A165b Is Protective and Restores Endothelial Glycocalyx in Diabetic Nephropathy. J Am Soc Nephrol 2014; 26:1889-904. [PMID: 25542969 DOI: 10.1681/asn.2014040350] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 10/15/2014] [Indexed: 01/11/2023] Open
Abstract
Diabetic nephropathy is the leading cause of ESRD in high-income countries and a growing problem across the world. Vascular endothelial growth factor-A (VEGF-A) is thought to be a critical mediator of vascular dysfunction in diabetic nephropathy, yet VEGF-A knockout and overexpression of angiogenic VEGF-A isoforms each worsen diabetic nephropathy. We examined the vasculoprotective effects of the VEGF-A isoform VEGF-A165b in diabetic nephropathy. Renal expression of VEGF-A165b mRNA was upregulated in diabetic individuals with well preserved kidney function, but not in those with progressive disease. Reproducing this VEGF-A165b upregulation in mouse podocytes in vivo prevented functional and histologic abnormalities in diabetic nephropathy. Biweekly systemic injections of recombinant human VEGF-A165b reduced features of diabetic nephropathy when initiated during early or advanced nephropathy in a model of type 1 diabetes and when initiated during early nephropathy in a model of type 2 diabetes. VEGF-A165b normalized glomerular permeability through phosphorylation of VEGF receptor 2 in glomerular endothelial cells, and reversed diabetes-induced damage to the glomerular endothelial glycocalyx. VEGF-A165b also improved the permeability function of isolated diabetic human glomeruli. These results show that VEGF-A165b acts via the endothelium to protect blood vessels and ameliorate diabetic nephropathy.
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Affiliation(s)
| | - Yan Qiu
- School of Physiology and Pharmacology and
| | | | | | - Chris Neal
- School of Physiology and Pharmacology and
| | | | - Amit Kaura
- School of Physiology and Pharmacology and
| | | | | | | | | | | | | | - Emma Wylie
- School of Physiology and Pharmacology and Academic Renal Unit, School of Clinical Science, University of Bristol, Bristol, United Kingdom
| | | | | | - George Cope
- Academic Renal Unit, School of Clinical Science, University of Bristol, Bristol, United Kingdom
| | | | | | - Raina Ramnath
- Academic Renal Unit, School of Clinical Science, University of Bristol, Bristol, United Kingdom
| | - Simon C Satchell
- Academic Renal Unit, School of Clinical Science, University of Bristol, Bristol, United Kingdom
| | - Rebecca R Foster
- Academic Renal Unit, School of Clinical Science, University of Bristol, Bristol, United Kingdom
| | - Kurt Ballmer-Hofer
- Biomolecular Research, Molecular Cell Biology, Paul Scherrer Institut, Villigen, Switzerland
| | - Lucy F Donaldson
- School of Physiology and Pharmacology and School of Life Sciences and
| | - Jonathan Barratt
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom; and
| | - Hans J Baelde
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - David O Bates
- Cancer Biology, Division of Oncology, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Andrew H J Salmon
- School of Physiology and Pharmacology and Academic Renal Unit, School of Clinical Science, University of Bristol, Bristol, United Kingdom;
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15
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Oltean S, Neal CR, Mavrou A, Patel P, Ahad T, Alsop C, Lee T, Sison K, Qiu Y, Harper SJ, Bates DO, Salmon AHJ. VEGF165b overexpression restores normal glomerular water permeability in VEGF164-overexpressing adult mice. Am J Physiol Renal Physiol 2012; 303:F1026-36. [PMID: 22811490 DOI: 10.1152/ajprenal.00410.2011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Vascular endothelial growth factor (VEGF)-A, a family of differentially spliced proteins produced by glomerular podocytes, maintains glomerular filtration barrier function. The expression of VEGF molecules is altered in human nephropathy. We aimed to determine the roles of the angiogenic VEGF(164) isoform, and the antiangiogenic VEGF(165)b isoform in mature, adult glomeruli in vivo using conditional, inducible transgenic overexpression systems in mice. Podocyte-specific VEGF(164) overexpression (up to 100 days) was induced by oral administration of doxycycline to adult podocin-rtTA/TetO-VEGF(164) double transgenic mice. The consequences of simultaneous overexpression of VEGF(164) and VEGF(165)b were assessed in triple-transgenic podocin-rtTA/TetO-VEGF(164)/nephrin-VEGF(165)b mice. Persistent VEGF(164) overexpression did not cause proteinuria but did increase glomerular ultrafiltration coefficient between days 3 and 7. Despite persistently increased VEGF(164) levels, glomerular ultrafiltration coefficient normalized by day 14 and remained normal up to 100 days. Decreased subpodocyte space (SPS) coverage of the glomerular capillary wall accompanied increased glomerular hydraulic conductivity in VEGF(164)-overexpressing mice. The changes in glomerular ultrafiltration coefficient and SPS coverage induced by 7 days of overexpression of VEGF(164) were not present in triple transgenic VEGF(164) and VEGF(165)b overexpressing mice. These results indicate that 1) the adult mouse glomerulus is relatively resistant to induced VEGF(164) overexpression. VEGF(164) overexpression altered glomerular permeability but did not cause proteinuria in these mature, adult animals; 2) the SPS is a dynamic VEGF-responsive modulator of glomerular function; and 3) the balance of VEGF isoforms plays a critical role in the regulation of glomerular permeability. VEGF(165)b is capable of preventing VEGF(164)-induced changes in glomerular permeability and ultrastructure in vivo.
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Affiliation(s)
- Sebastian Oltean
- Microvascular Research Laboratories, School of Physiology and Pharmacology, Univ. of Bristol, Preclinical Veterinary School, Southwell St., Bristol, United Kingdom. BS2 8EJ
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16
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Salmon AHJ, Ferguson JK, Burford JL, Gevorgyan H, Nakano D, Harper SJ, Bates DO, Peti-Peterdi J. Loss of the endothelial glycocalyx links albuminuria and vascular dysfunction. J Am Soc Nephrol 2012; 23:1339-50. [PMID: 22797190 DOI: 10.1681/asn.2012010017] [Citation(s) in RCA: 185] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Patients with albuminuria and CKD frequently have vascular dysfunction but the underlying mechanisms remain unclear. Because the endothelial surface layer, a meshwork of surface-bound and loosely adherent glycosaminoglycans and proteoglycans, modulates vascular function, its loss could contribute to both renal and systemic vascular dysfunction in proteinuric CKD. Using Munich-Wistar-Fromter (MWF) rats as a model of spontaneous albuminuric CKD, multiphoton fluorescence imaging and single-vessel physiology measurements revealed that old MWF rats exhibited widespread loss of the endothelial surface layer in parallel with defects in microvascular permeability to both water and albumin, in both continuous mesenteric microvessels and fenestrated glomerular microvessels. In contrast to young MWF rats, enzymatic disruption of the endothelial surface layer in old MWF rats resulted in neither additional loss of the layer nor additional changes in permeability. Intravenous injection of wheat germ agglutinin lectin and its adsorption onto the endothelial surface layer significantly improved glomerular albumin permeability. Taken together, these results suggest that widespread loss of the endothelial surface layer links albuminuric kidney disease with systemic vascular dysfunction, providing a potential therapeutic target for proteinuric kidney disease.
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Affiliation(s)
- Andrew H J Salmon
- Microvascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol, UK.
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17
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18
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Wyss HM, Henderson JM, Byfield FJ, Bruggeman LA, Ding Y, Huang C, Suh JH, Franke T, Mele E, Pollak MR, Miner JH, Janmey PA, Weitz DA, Miller RT. Biophysical properties of normal and diseased renal glomeruli. Am J Physiol Cell Physiol 2011; 300:C397-405. [PMID: 21123730 PMCID: PMC3063968 DOI: 10.1152/ajpcell.00438.2010] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 11/30/2010] [Indexed: 11/22/2022]
Abstract
The mechanical properties of tissues and cells including renal glomeruli are important determinants of their differentiated state, function, and responses to injury but are not well characterized or understood. Understanding glomerular mechanics is important for understanding renal diseases attributable to abnormal expression or assembly of structural proteins and abnormal hemodynamics. We use atomic force microscopy (AFM) and a new technique, capillary micromechanics, to measure the elastic properties of rat glomeruli. The Young's modulus of glomeruli was 2,500 Pa, and it was reduced to 1,100 Pa by cytochalasin and latunculin, and to 1,400 Pa by blebbistatin. Cytochalasin or latrunculin reduced the F/G actin ratios of glomeruli but did not disrupt their architecture. To assess glomerular biomechanics in disease, we measured the Young's moduli of glomeruli from two mouse models of primary glomerular disease, Col4a3(-/-) mice (Alport model) and Tg26(HIV/nl) mice (HIV-associated nephropathy model), at stages where glomerular injury was minimal by histopathology. Col4a3(-/-) mice express abnormal glomerular basement membrane proteins, and Tg26(HIV/nl) mouse podocytes have multiple abnormalities in morphology, adhesion, and cytoskeletal structure. In both models, the Young's modulus of the glomeruli was reduced by 30%. We find that glomeruli have specific and quantifiable biomechanical properties that are dependent on the state of the actin cytoskeleton and nonmuscle myosins. These properties may be altered early in disease and represent an important early component of disease. This increased deformability of glomeruli could directly contribute to disease by permitting increased distension with hemodynamic force or represent a mechanically inhospitable environment for glomerular cells.
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Affiliation(s)
- Hans M Wyss
- Physics, Harvard University, Cambridge, Massachusetts, USA
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19
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Strilić B, Kucera T, Lammert E. Formation of cardiovascular tubes in invertebrates and vertebrates. Cell Mol Life Sci 2010; 67:3209-18. [PMID: 20490602 PMCID: PMC11115780 DOI: 10.1007/s00018-010-0400-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Revised: 04/17/2010] [Accepted: 05/03/2010] [Indexed: 12/13/2022]
Abstract
The cardiovascular system developed early in evolution and is pivotal for the transport of oxygen, nutrients, and waste products within the organism. It is composed of hollow tubular structures and has a high level of complexity in vertebrates. This complexity is, at least in part, due to the endothelial cell lining of vertebrate blood vessels. However, vascular lumen formation by endothelial cells is still controversially discussed. For example, it has been suggested that the lumen mainly forms via coalescence of large intracellular vacuoles generated by pinocytosis. Alternatively, it was proposed that the vascular lumen initiates extracellularly between adjacent apical endothelial cell surfaces. Here we discuss invertebrate and vertebrate cardiovascular lumen formation and highlight the possible modes of blood vessel formation. Finally, we point to the importance of a better understanding of vascular lumen formation for treating human pathologies, including cancer and coronary heart disease.
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Affiliation(s)
- Boris Strilić
- Institute of Metabolic Physiology, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany.
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20
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Qiu Y, Ferguson J, Oltean S, Neal CR, Kaura A, Bevan H, Wood E, Sage LM, Lanati S, Nowak DG, Salmon AHJ, Bates D, Harper SJ. Overexpression of VEGF165b in podocytes reduces glomerular permeability. J Am Soc Nephrol 2010; 21:1498-509. [PMID: 20688932 DOI: 10.1681/asn.2009060617] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The observation that therapeutic agents targeting vascular endothelial growth factor-A (VEGF-A) associate with renal toxicity suggests that VEGF plays a role in the maintenance of the glomerular filtration barrier. Alternative mRNA splicing produces the VEGF(xxx)b family, which consists of antiangiogenic peptides that reduce permeability and inhibit tumor growth; the contribution of these peptides to normal glomerular function is unknown. Here, we established and characterized heterozygous and homozygous transgenic mice that overexpress VEGF(165)b specifically in podocytes. We confirmed excess production of glomerular VEGF(165)b by reverse transcriptase-PCR, immunohistochemistry, and ELISA in both heterozygous and homozygous animals. Macroscopically, the mice seemed normal up to 18 months of age, unlike the phenotype of transgenic podocyte-specific VEGF(164)-overexpressing mice. Animals overexpressing VEGF(165)b, however, had a significantly reduced normalized glomerular ultrafiltration fraction with accompanying changes in ultrastructure of the glomerular filtration barrier on the vascular side of the glomerular basement membrane. These data highlight the contrasting properties of VEGF splice variants and their impact on glomerular function and phenotype.
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Affiliation(s)
- Yan Qiu
- Microvascular Research Laboratories, Department Physiology and Pharmacology, Bristol Heart Institute, Preclinical Veterinary School, Southwell Street, Bristol, BS2 8EJ, UK
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21
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Oltean S, Ferguson J, Qiu Y, Salmon AH, Quaggin S, Harper SJ, Bates DO. Contrasting properties of VEGF165 and VEGF165b splicing isoforms on glomerular water permeability in transgenic mice and complementary rescue of the phenotype. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.774.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Sebastian Oltean
- Physiology and PharmacologyUniversity of BristolBristolUnited Kingdom
| | - Joanne Ferguson
- Physiology and PharmacologyUniversity of BristolBristolUnited Kingdom
| | - Yan Qiu
- Physiology and PharmacologyUniversity of BristolBristolUnited Kingdom
| | - Andrew H Salmon
- Physiology and PharmacologyUniversity of BristolBristolUnited Kingdom
| | | | - Steve J Harper
- Physiology and PharmacologyUniversity of BristolBristolUnited Kingdom
| | - David O Bates
- Physiology and PharmacologyUniversity of BristolBristolUnited Kingdom
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22
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Salmon AHJ, Neal CR, Sage LM, Glass CA, Harper SJ, Bates DO. Angiopoietin-1 alters microvascular permeability coefficients in vivo via modification of endothelial glycocalyx. Cardiovasc Res 2009; 83:24-33. [PMID: 19297368 PMCID: PMC2695703 DOI: 10.1093/cvr/cvp093] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS In this study, we wished to determine whether angiopoietin-1 (Ang1) modified the permeability coefficients of non-inflamed, intact continuous, and fenestrated microvessels in vivo and to elucidate the underlying cellular mechanisms. METHODS AND RESULTS Permeability coefficients were measured using the Landis-Michel technique (in frog and rat mesenteric microvessels) and an oncopressive permeability technique (in glomeruli). Ang1 decreased water permeability (L(P): hydraulic conductivity) in continuous and fenestrated microvessels and increased the retention of albumin (sigma: reflection coefficient) in continuous microvessels. Endothelial glycocalyx is common to these anatomically distinct microvascular beds, and contributes to the magnitude of both L(P) and sigma. Ang1 treatment increased the depth of endothelial glycocalyx in intact microvessels and increased the content of glycosaminoglycan of cultured microvascular endothelial cell supernatant. Ang1 also prevented the pronase-induced increase in L(P) (attributable to selective removal of endothelial glycocalyx by pronase) by restoration of glycocalyx at the endothelial cell surface. The reduction in permeability was inhibited by a cell transport inhibitor, Brefeldin. CONCLUSION Ang1 modifies basal microvessel permeability coefficients, in keeping with previous reports demonstrating reduced solute flux in inflamed vessels. Anatomical, biochemical, and physiological evidence indicates that modification of endothelial glycocalyx is a novel mechanism of action of Ang1 that contributes to these effects.
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Affiliation(s)
- Andrew H J Salmon
- Department of Physiology and Pharmacology, Preclinical Veterinary School, Microvascular Research Laboratories, Bristol Heart Institute, University of Bristol, Southwell Street, Bristol, UK
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Axelsson J, Rippe A, Venturoli D, Swärd P, Rippe B. Effects of early endotoxemia and dextran-induced anaphylaxis on the size selectivity of the glomerular filtration barrier in rats. Am J Physiol Renal Physiol 2008; 296:F242-8. [PMID: 19004933 DOI: 10.1152/ajprenal.90263.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study was performed to investigate the glomerular permeability alterations responsible for the microalbuminuria occurring in endotoxemia and during anaphylactic shock. In anesthetized Wistar rats, the left ureter was catheterized for urine collection while, simultaneously, blood access was achieved. Endotoxemia was induced by lipopolysaccharide (LPS) from Escherichia coli, and glomerular permeability was assessed at 60 and 90 (n = 7) and 120 (n = 7) min. Anaphylaxis was induced by a bolus dose of Dextran-70, and glomerular permeability assessed at 5 min (n = 8) and 40 min (n = 9). Sham animals were followed for either 5 or 120 min. The glomerular sieving coefficients (theta) to fluorescein isothiocyanate-Ficoll (70/400) were determined from plasma and urine samples and assessed using size-exclusion chromatography (HPLC). After start of the LPS infusion (2 h), but not at 60 or 90 min, theta for Ficoll(70A) had increased markedly [from 2.91 x 10(-5) +/- 6.33 x 10(-6) to 7.78 x 10(-5) +/- 6.21 x 10(-6) (P < 0.001)]. In anaphylaxis, there was a large increase in theta for Ficolls >60 A in molecular radius already at 5 min, but the glomerular permeability was completely restored at 40 min. In conclusion, there was a transient, immediate increment of glomerular permeability in dextran-induced anaphylaxis, which was completely reversible within 40 min. By contrast, endotoxemia caused an increase in glomerular permeability that was manifest first after 2 h. In both cases, theta to large Ficoll molecules were markedly increased, reflecting an increase in the number of large pores in the glomerular filter.
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Affiliation(s)
- Josefin Axelsson
- Department of Nephrology, University Hospital of Lund, S-211 85 Lund, Sweden
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Salmon AHJ, Toma I, Sipos A, Muston PR, Harper SJ, Bates DO, Neal CR, Peti-Peterdi J. Evidence for restriction of fluid and solute movement across the glomerular capillary wall by the subpodocyte space. Am J Physiol Renal Physiol 2007; 293:F1777-86. [PMID: 17804486 DOI: 10.1152/ajprenal.00187.2007] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The glomerular filtration barrier (GFB) is generally considered to consist of three layers: fenestrated glomerular endothelium, glomerular basement membrane, and filtration slits between adjacent podocyte foot processes. Detailed anatomic examination of the GFB has revealed a novel abluminal structure, the subpodocyte space (SPS), identified as the labyrinthine space between the underside of podocyte cell body/primary processes and the foot processes. The SPS covers 50–65% of the filtration surface of the GFB, indicating that SPS may influence glomerular permeability. We have examined the contribution of the SPS to the permeability characteristics of the GFB using multiphoton microscopy techniques in isolated, perfused glomeruli and in the intact kidney in vivo. SPS were identified using this technique, with comparable dimensions to SPS examined with electron microscopy. The passage of the intermediate-weight molecule rhodamine-conjugated 10-kDa dextran, but not the low-weight molecule lucifer yellow (≈450 Da), accumulated in SPS-covered regions of the GFB, compared with GFB regions not covered by SPS (“naked regions”). Net lucifer yellow flux (taken to indicate fluid flux) through identifiable SPS regions was calculated to be 66–75% of that occurring through naked regions. These observations indicate both ultrafiltration and hydraulic resistance imparted by the SPS, demonstrating the potential physiological contribution of the SPS to glomerular permeability.
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Affiliation(s)
- Andrew H J Salmon
- ZNI 335, Zilkha Neurogenetic Institute, 1501 San Pablo St., Keck School of Medicine, Univ. of Southern California, Los Angeles, CA 90089, USA
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Rosivall L, Mirzahosseini S, Toma I, Sipos A, Peti-Peterdi J. Fluid flow in the juxtaglomerular interstitium visualized in vivo. Am J Physiol Renal Physiol 2006; 291:F1241-7. [PMID: 16868308 DOI: 10.1152/ajprenal.00203.2006] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Earlier electron microscopy studies demonstrated morphological signs of fluid flow in the juxtaglomerular apparatus (JGA), including fenestrations of the afferent arteriole (AA) endothelium facing renin granular cells. We aimed to directly visualize fluid flow in the JGA, the putative function of the fenestrated endothelium, using intravital multiphoton microscopy of Munich-Wistar rats and C57BL6 mice. Renin content of the AA correlated strongly with the length of the fenestrated, filtering AA segment. Fluorescence of the extracellular fluid marker lucifer yellow (LY) injected into the cannulated femoral vein in bolus was followed in the renal cortex by real-time imaging. LY was detected in the interstitium around the JG AA before the plasma LY filtered into Bowman's capsule and early proximal tubule. The fluorescence intensity of LY in the JGA interstitium was 17.9 ± 3.5% of that in the AA plasma ( n = 6). The JGA fluid flow was oscillatory, consisting of two components: a fast (one every 5–10 s) and a slow (one every 45–50 s) oscillation, most likely due to the rapid transmission of both the myogenic and tubuloglomerular feedback (TGF)-mediated hemodynamic changes. LY was also detected in the distal tubular lumen about 2–5 s later than in the AA, indicating the flow of JGA interstitial fluid through the macula densa. In the isolated microperfused JGA, blocking the early proximal tubule with a micropipette caused significant increases in MD cell volume by 62 ± 4% ( n = 4) and induced dilation of the intercellular lateral spaces. In summary, significant and dynamic fluid flow exists in the JGA which may help filter the released renin into the renal interstitium (endocrine function). It may also modulate TGF and renin signals in the JGA (hemodynamic function).
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Affiliation(s)
- László Rosivall
- Hungarian Academy of Sciences and Semmelweis University Nephrology Research Group, Semmelweis University Faculty of Medicine, Budapest, Hungary
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