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Malatiali S, Francis I, Barac-Nieto M. Insulin Prevents Hyperfiltration and Proteinuria but Not Glomerular Hypertrophy and Increases Mesangial Matrix Expansion in Diabetic Rats. Med Princ Pract 2017; 26:78-83. [PMID: 27643698 PMCID: PMC5588318 DOI: 10.1159/000450864] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 09/18/2016] [Indexed: 11/21/2022] Open
Abstract
OBJECTIVE The aim of this work was to study the effect of 7 days of strict glycemic control with insulin on glomerular function and structure in streptozotocin (STZ)-diabetic rats. MATERIALS AND METHODS Three groups of adult male Fischer rats were studied: controls (n = 15), diabetics (n = 15), and insulin-treated diabetics (n = 15). Diabetes was induced by treating the rats with STZ (55 mg/kg i.p.). One week after the induction of diabetes, blood glucose, protein excretion rate (PER), glomerular filtration rate (GFR), and renal plasma flow (RPF) were estimated in each group. Furthermore, morphometric analysis was performed to estimate the tuft volume and changes in mesangial matrix area. The results are expressed as the mean ± SEM. RESULTS STZ diabetes caused significant increases in GFR (0.89 ± 0.1 to 1.21 ± 0.1 mL/min/100 g; p < 0.01) and RPF (1.78 ± 0.37 to 3.32 ± 0.6 mL/min/100 g; p < 0.05). Furthermore, the diabetic rats had higher glomerular volumes but mesangial matrix areas similar to controls. Insulin treatment prevented the increases in blood glucose (4.5 ± 0.2 mM), PER (66.1 ± 7.8 mg/day), GFR (0.6 ± 0.07 mL/min/100 g), and RPF (1.72 ± 0.36 mL/min/100 g), but did not prevent glomerular hypertrophy (21.7% increase), but induced mesangial matrix expansion (25% increase). CONCLUSIONS Insulin prevented the diabetes-induced hyperfiltration and proteinuria, but did not prevent glomerular growth, and induced mesangial expansion. Hyperglycemic episodes could be partly responsible for persistent glomerular growth and accelerated mesangial growth.
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Affiliation(s)
- Slava Malatiali
- Department of Physiology, Faculty of Medicine, Kuwait University, Safat, Kuwait
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Bernardi S, Toffoli B, Zennaro C, Bossi F, Losurdo P, Michelli A, Carretta R, Mulatero P, Fallo F, Veglio F, Fabris B. Aldosterone effects on glomerular structure and function. J Renin Angiotensin Aldosterone Syst 2015; 16:730-8. [PMID: 26283678 DOI: 10.1177/1470320315595568] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 06/11/2015] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE Experimental evidence suggests that aldosterone directly contributes to organ damage by promoting cell growth, fibrosis, and inflammation. Based on these premises, this work aimed to assess the glomerular effects of aldosterone, alone and in combination with salt. METHODS After undergoing uninephrectomy, 75 rats were allocated to five groups: control, salt diet, aldosterone, aldosterone + salt diet, aldosterone + salt diet and eplerenone, and they were all studied for four weeks. We focused on glomerular structural, functional, and molecular changes, including slit diaphragm components, local renin-angiotensin system activation, as well as pro-oxidative and profibrotic changes. RESULTS Aldosterone significantly increased systolic blood pressure, led to glomerular hypertrophy, mesangial expansion, and it significantly increased the glomerular permeability to albumin and the albumin excretion rate, indicating the presence of glomerular damage. These effects were worsened by adding salt to aldosterone, while they were reduced by eplerenone. Aldosterone-induced glomerular damage was associated with glomerular angiotensin-converting enzyme (ACE) 2 downregulation, with ACE/ACE2 ratio increase, ANP decrease, as well as with glomerular pro-oxidative and profibrotic changes. CONCLUSIONS Aldosterone damages not only the structure but also the function of the glomerulus. ACE/ACE2 upregulation, ACE2 and ANP downregulation, and pro-oxidative and profibrotic changes are possible mechanisms accounting for aldosterone-induced glomerular injury.
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Affiliation(s)
- Stella Bernardi
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
| | - Barbara Toffoli
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy Centre for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Switzerland
| | - Cristina Zennaro
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
| | - Fleur Bossi
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
| | - Pasquale Losurdo
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
| | - Andrea Michelli
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
| | - Renzo Carretta
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
| | - Paolo Mulatero
- Division of Internal Medicine and Hypertension, University of Torino, Italy
| | - Francesco Fallo
- Department of Medical and Surgical Sciences, University of Padova, Italy
| | - Franco Veglio
- Division of Internal Medicine and Hypertension, University of Torino, Italy
| | - Bruno Fabris
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
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3
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Zennaro C, Rastaldi MP, Pascolo L, Stebel M, Trevisan E, Artero M, Tiribelli C, Di Maso V, Carraro M. Podocyte expression of membrane transporters involved in puromycin aminonucleoside-mediated injury. PLoS One 2013; 8:e66159. [PMID: 23840417 PMCID: PMC3688733 DOI: 10.1371/journal.pone.0066159] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 05/02/2013] [Indexed: 12/15/2022] Open
Abstract
Several complex mechanisms contribute to the maintenance of the intricate ramified morphology of glomerular podocytes and to interactions with neighboring cells and the underlying basement membrane. Recently, components of small molecule transporter families have been found in the podocyte membrane, but expression and function of membrane transporters in podocytes is largely unexplored. To investigate this complex field of investigation, we used two molecules which are known substrates of membrane transporters, namely Penicillin G and Puromycin Aminonucleoside (PA). We observed that Penicillin G pre-administration prevented both in vitro and in vivo podocyte damage caused by PA, suggesting the engagement of the same membrane transporters by the two molecules. Indeed, we found that podocytes express a series of transporters which are known to be used by Penicillin G, such as members of the Organic Anion Transporter Polypeptides (OATP/Oatp) family of influx transporters, and P-glycoprotein, a member of the MultiDrug Resistance (MDR) efflux transporter family. Expression of OATP/Oatp transporters was modified by PA treatment. Similarly, in vitro PA treatment increased mRNA and protein expression of P-glycoprotein, as well as its activity, confirming the engagement of the molecule upon PA administration. In summary, we have characterized some of the small molecule transporters present at the podocyte membrane, focusing on those used by PA to enter and exit the cell. Further investigation will be needed to understand precisely the role of these transporter families in maintaining podocyte homeostasis and in the pathogenesis of podocyte injury.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- Animals
- Antibiotics, Antineoplastic/metabolism
- Antibiotics, Antineoplastic/toxicity
- Biological Transport/drug effects
- Cell Adhesion
- Cell Line, Tumor
- Cell Membrane Permeability
- Cell Proliferation
- Cell Survival/drug effects
- Cyclosporine/pharmacology
- Cytoprotection
- Gene Expression/drug effects
- Humans
- Kidney Glomerulus/cytology
- Kidney Glomerulus/drug effects
- Male
- Organic Anion Transporters/antagonists & inhibitors
- Organic Anion Transporters/genetics
- Organic Anion Transporters/metabolism
- Penicillin G/metabolism
- Penicillin G/pharmacology
- Podocytes/drug effects
- Podocytes/metabolism
- Puromycin Aminonucleoside/metabolism
- Puromycin Aminonucleoside/toxicity
- Rats
- Rats, Sprague-Dawley
- Serum Albumin/metabolism
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Affiliation(s)
- Cristina Zennaro
- Department of Medical, Surgery and Health Sciences, Università degli Studi di Trieste, Trieste, Italy
| | - Maria Pia Rastaldi
- Renal Research Laboratory, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico & Fondazione D’Amico per la Ricerca sulle Malattie Renali, Milano, Italy
| | - Lorella Pascolo
- IRCCS Burlo Garofolo Istituto per la Cura a Carattere Scientifico Materno Infantile, Trieste, Italy
| | - Marco Stebel
- Department of Life Sciences, Università degli Studi di Trieste, Trieste, Italy
| | - Elisa Trevisan
- Department of Life Sciences, Università degli Studi di Trieste, Trieste, Italy
| | - Mary Artero
- Azienda Ospedaliero-Universitaria Ospedali di Riuniti di Trieste, Trieste, Italy
| | - Claudio Tiribelli
- Department of Medical, Surgery and Health Sciences, Università degli Studi di Trieste, Trieste, Italy
- Liver Research Center, AREA Science Park, Trieste, Italy
| | - Vittorio Di Maso
- Department of Medical, Surgery and Health Sciences, Università degli Studi di Trieste, Trieste, Italy
| | - Michele Carraro
- Department of Medical, Surgery and Health Sciences, Università degli Studi di Trieste, Trieste, Italy
- * E-mail:
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Swärd P, Rippe B. Acute and sustained actions of hyperglycaemia on endothelial and glomerular barrier permeability. Acta Physiol (Oxf) 2012; 204:294-307. [PMID: 21812939 DOI: 10.1111/j.1748-1716.2011.02343.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Microalbuminuria is an established marker of systemic endothelial dysfunction, which for patients with diabetes signals an increased risk of both diabetic nephropathy and cardiovascular complications. A better understanding of the pathogenesis of microalbuminuria is important in the quest of finding new approaches to treat patients with diabetes. Direct acute effects of episodes of hyperglycaemia (HG) could have implications for the microalbuminuria seen in early diabetes before renal structural alterations have started, especially in those patients with poor glycaemic control. This review summarizes the literature evidence that acute or sustained HG may lead to an increased vascular or glomerular permeability. Special focus is on glomerular barrier permeability. There is evidence in the literature that HG increases systemic capillary and glomerular barrier permeability within 20-30 min in vivo in rats and mice. Furthermore, exposure of monolayers of cultured endothelial cells to HG has been shown to increase monolayer permeability rapidly and transiently (during 60-100 min). Instant cellular changes following F-actin cytoskeleton rearrangements, which could be abrogated by Rho-kinase (ROCK) inhibition, are implicated. Data in this review also suggest that activation of protein kinase C, the polyol pathway, and an increased release of reactive oxygen species (ROS) and cytokines could contribute to the increase in barrier permeability induced by HG. Recent in vitro data from cultured podocyte monolayers also designates a role of insulin in acute podocyte F-actin remodelling, underpinning the complexity of the mechanisms leading to glomerular and endothelial barrier alterations in diabetes mellitus.
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Affiliation(s)
- P Swärd
- Department of Nephrology, University of Lund, University Hospital of Lund, Sweden
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Bernardi S, Toffoli B, Zennaro C, Tikellis C, Monticone S, Losurdo P, Bellini G, Thomas MC, Fallo F, Veglio F, Johnston CI, Fabris B. High-salt diet increases glomerular ACE/ACE2 ratio leading to oxidative stress and kidney damage. Nephrol Dial Transplant 2011; 27:1793-800. [PMID: 22036945 DOI: 10.1093/ndt/gfr600] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Angiotensin II (AngII) contributes to salt-driven kidney damage. In this study, we aimed at investigating whether and how the renal damage associated with a high-salt diet could result from changes in the ratio between angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2). METHODS Forty-eight rats randomly allocated to three different dietary contents of salt were studied for 4 weeks after undergoing a left uninephrectomy. We focussed on kidney functional, structural and molecular changes. At the same time, we studied kidney molecular changes in 20 weeks old Ace2-knockout mice (Ace2KO), with and without ACE inhibition. RESULTS A high salt content diet significantly increased the glomerular ACE/ACE2 ratio. This was associated with increased oxidative stress. To assess whether these events were related, we measured renal oxidative stress in Ace2KO, and found that the absence of ACE2 promoted oxidative stress, which could be prevented by ACE inhibition. CONCLUSION One of the mechanisms by which a high-salt diet leads to renal damage seems to be the modulation of the ACE/ACE2 ratio which in turn is critical for the cause of oxidative stress, through AngII.
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Affiliation(s)
- Stella Bernardi
- Department of Morphology and Embriology, University of Ferrara, Ferrara, Italy.
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Satchell SC, Tooke JE. What is the mechanism of microalbuminuria in diabetes: a role for the glomerular endothelium? Diabetologia 2008; 51:714-25. [PMID: 18347777 PMCID: PMC2292427 DOI: 10.1007/s00125-008-0961-8] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Accepted: 12/20/2007] [Indexed: 12/11/2022]
Abstract
Microalbuminuria is an important risk factor for cardiovascular disease and progressive renal impairment. This holds true in the general population and particularly in those with diabetes, in whom it is common and marks out those likely to develop macrovascular disease and progressive renal impairment. Understanding the pathophysiological mechanisms through which microalbuminuria occurs holds the key to designing therapies to arrest its development and prevent these later manifestations. Microalbuminuria arises from the increased passage of albumin through the glomerular filtration barrier. This requires ultrastructural changes rather than alterations in glomerular pressure or filtration rate alone. Compromise of selective glomerular permeability can be confirmed in early diabetic nephropathy but does not correlate well with reported glomerular structural changes. The loss of systemic endothelial glycocalyx--a protein-rich surface layer on the endothelium--in diabetes suggests that damage to this layer represents this missing link. The epidemiology of microalbuminuria reveals a close association with systemic endothelial dysfunction and with vascular disease, also implicating glomerular endothelial dysfunction in microalbuminuria. Our understanding of the metabolic and hormonal sequelae of hyperglycaemia is increasing, and we consider these in the context of damage to the glomerular filtration barrier. Reactive oxygen species, inflammatory cytokines and growth factors are key players in this respect. Taken together with the above observations and the presence of generalised endothelial dysfunction, these considerations lead to the conclusion that glomerular endothelial dysfunction, and in particular damage to its glycocalyx, represents the most likely initiating step in diabetic microalbuminuria.
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Affiliation(s)
- S C Satchell
- Academic Renal Unit, University of Bristol, Southmead Hospital, Bristol, BS10 5NB, UK.
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Lin CL, Wang FS, Kuo YR, Huang YT, Huang HC, Sun YC, Kuo YH. Ras modulation of superoxide activates ERK-dependent fibronectin expression in diabetes-induced renal injuries. Kidney Int 2006; 69:1593-600. [PMID: 16572112 DOI: 10.1038/sj.ki.5000329] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Although previous studies have demonstrated that diabetic nephropathy is attributable to early extracellular matrix accumulation in glomerular mesangial cells, the molecular mechanism by which high glucose induces matrix protein deposition remains not fully elucidated. Rat mesangial cells pretreated with or without inhibitors were cultured in high-glucose or advanced glycation end product (AGE) conditions. Streptozotocin-induced diabetic rats were given superoxide dismutase (SOD)-conjugated propylene glycol to scavenge superoxide. Transforming growth factor (TGF)-beta1, fibronectin expression, Ras, ERK, p38, and c-Jun activation of glomerular mesangial cells or urinary albumin secretion were assessed. Superoxide, not nitric oxide or hydrogen peroxide, mediated high glucose- and AGE-induced TGF-beta1 and fibronectin expression. Pretreatment with diphenyliodonium, not allopurinol or rotenone, reduced high-glucose and AGE augmentation of superoxide synthesis and fibronection expression. High glucose and AGEs rapidly enhanced Ras activation and progressively increased cytosolic ERK and nuclear c-Jun activation. Inhibiting Ras by manumycin A reduced the stimulatory effects of high glucose and AGEs on superoxide and fibronectin expression. SOD or PD98059 pretreatment reduced high-glucose and AGE promotion of ERK and c-Jun activation. Exogenous SOD treatment in diabetic rats significantly attenuated diabetes induction of superoxide, urinary albumin excretion, 8-hydroxy-2'-deoxyguanosine, TGF-beta1, and fibronectin immunoreactivities in renal glomerular mesangial cells. Ras induction of superoxide activated ERK-dependent fibrosis-stimulatory factor and extracellular matrix gene transcription of mesangial cells. Reduction of oxidative stress by scavenging superoxide may provide an alternative strategy for controlling diabetes-induced early renal injury.
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Affiliation(s)
- C-L Lin
- Department of Nephrology, Chiayi Chang Gung Memorial Hospital & Graduate Institute of Clinical Medical Sciences, College of Medicine, Chang Gung University, Chiayi, Taiwan.
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8
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Abstract
The development of irreversible renal changes in diabetes mellitus, such as glomerulosclerosis and tubulointerstitial fibrosis, are always preceded by the early hypertrophic processes in the glomerular and tubular compartment. However, the role of hypertrophy of podocyte in the diabetic nephropathy have not been fully elucidated yet. Observation came from a cross sectional study in diabetic Pima Indians suggests that subjects with clinical nephropathy had fewer podocytes per glomerulus than those without nephropathy. Since podocytes are thought to be incapable of replication, this observation suggests that podocyte loss, or perhaps a low podocyte number per glomerulus, contributes to the development and progression of diabetic glomerulosclerosis. Podocyte hypertrophy caused by high glucose concentration leads to podocyte loss and is a new insight of pathogenesis of diabetic nephropathy; and it also provides us with new therapeutic strategies in diabetic nephropathy.
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Affiliation(s)
- Nam Ho Kim
- Division of Nephrology, Department of Internal Medicine, Chonnam National University Medical School, Hakdong, Gwangju, South Korea.
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9
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Rangan GK, Pippin JW, Coombes JD, Couser WG. C5b-9 does not mediate chronic tubulointerstitial disease in the absence of proteinuria. Kidney Int 2005; 67:492-503. [PMID: 15673297 DOI: 10.1111/j.1523-1755.2005.67106.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND In nephrotic glomerular diseases, the intratubular assembly of the membrane attack complex (C5b-9) is one of the principal mediators of chronic tubulointerstitial damage. Here, we examined whether C5b-9 has a pathogenic role in tubulointerstitial disease in the absence of proteinuria. METHODS Three pathophysiologically distinct models of nonproteinuric chronic tubulointerstitial disease were induced in Piebald-Viral-Glaxo (PVG) rats, with or without C6 deficiency (C6+ and C6): (1) unilateral ureteric obstruction (UUO, days 1, 3, 6, 14, and 21; N= 5-6/group); (2) cyclosporine (CsA) nephropathy (15 mg/kg SC daily with 0.05% sodium diet; day 14, 35 N= 9/group); and (3) streptozotocin (STZ)-induced diabetes (day 90, N= 8/group). RESULTS The peritubular deposition of C5b-9 increased in all three models. In UUO, the number of vimentin-positive tubules, interstitial volume expansion, and monocyte accumulation were similar in both the C6+ and C6- groups at all time points. There was a trend toward an earlier peak in myofibroblast accumulation in C6- rats with UUO (d3 vs. d6; P= 0.05), but this did not prevent fibrosis at later time points. In CsA nephropathy, cortical tubulointerstitial damage was also similar in both C6+ and C6- groups on day 14, despite equivalent CsA trough levels. Finally, in STZ-induced diabetes, rats did not develop proteinuria, and tubulointerstitial disease (distal tubule glycogen nephrosis, interstitial volume expansion, and tubular dilatation) was not altered by C6 deficiency. CONCLUSION These data suggest that, in contrast to proteinuric states, C5b-9 does not have a significant impact on the progression of tubulointerstitial damage in nonproteinuric chronic renal disease.
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Affiliation(s)
- Gopala K Rangan
- Division of Nephrology, University of Washington Medical Center, Seattle, Washington, USA.
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Okada K, Matsumoto K, Takahashi S. Oral Adsorbent Prevents Reduction of Anionic Sites of the Glomerular Basement Membrane in Diabetic Nephropathy. ACTA ACUST UNITED AC 2004; 99:e56-62. [PMID: 15627801 DOI: 10.1159/000082869] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Accepted: 08/05/2004] [Indexed: 11/19/2022]
Abstract
BACKGROUND AST-120, an oral adsorbent, inhibits progression of diabetic nephropathy by reducing albuminuria. The purpose of the present study was to explore the mechanism underlying the protective effect of AST-120 against albuminuria. METHODS Twenty-four male Sprague-Dawley rats underwent intravenous injection of streptozotocin and subsequent uninephrectomy. Half of the rats were fed standard rat chow, and the other half were fed rat chow containing AST-120. All rats were killed at week 6 after a clearance study. RESULTS There were no significant differences in body weight, kidney weight, urinary volume, blood pressure, blood glucose or inulin clearance between the two groups at week 6. However, urinary albumin excretion at week 6 was significantly lower in the AST-120 group than in the control group (p < 0.05). Light microscopic observation showed that the planar area of glomeruli was significantly smaller in the AST-120 group than in the control group (p < 0.01), and the shortest diameter of proximal tubules was less in the AST-120 group than in the control group (p < 0.01). Electron microscopic observation showed a significantly greater number of anionic sites on the lamina rara externa of the glomerular basement membrane in the AST-120 group than in the control group (p < 0.01). CONCLUSION We conclude that AST-120 reduces albuminuria by preventing the decrease in the number of anionic sites in the glomerular basement membrane in rats with diabetic nephropathy. In addition, AST-120 inhibits the appearance of glomerular and tubular hypertrophy.
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Affiliation(s)
- Kazuyoshi Okada
- Division of Nephrology and Endocrinology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.
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Russo LM, Osicka TM, Brammar GC, Candido R, Jerums G, Comper WD. Renal processing of albumin in diabetes and hypertension in rats: possible role of TGF-beta1. Am J Nephrol 2003; 23:61-70. [PMID: 12481143 DOI: 10.1159/000068039] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS Recent studies show that albuminuria may be the result of changes in post-glomerular cellular uptake and processing of albumin. This study aims to determine whether this processing is disrupted in diabetes and/or hypertension. METHODS Diabetes (d) was induced using streptozotocin in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY) and studied after 8, 16 and 24 weeks of disease. Intact albumin excretion was determined by radioimmunoassay. Total albumin was determined by [(14)C]albumin. Lysosomal activity was determined by dextran sulfate desulfation. Renal TGF-beta1 and transforming growth factor-beta1 inducible gene-h3 mRNA (betaig-h3) expression was determined by real time RT-PCR. RESULTS SHR-c rats exhibited an increase in intact albuminuria without significant change in total albumin excretion (intact plus albumin-derived peptides). For WKY-d rats, intact albuminuria developed initially, followed by an increase in total albumin excretion primarily in the form of albumin peptides (peptiduria). SHR-d rats exhibited both increases in peptiduria and intact albuminuria. There was no increase in glomerular permeability at 24 weeks for polydisperse [(3)H]Ficoll in all groups. Increased renal TGF-beta1 and betaig-h3 expression was correlated with a decrease in dextran sulfate desulfation and increased intact albuminuria independent of peptiduria. CONCLUSION Increased albumin excretion in hypertension and/or diabetes is manifested in different forms independent of glomerular permeability.
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Affiliation(s)
- Leileata M Russo
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
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12
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Abstract
Type 1 diabetes is commonly associated with microvascular complications. Most of the microvascular blood vessels are involved but those in the kidney, retina and large nerves exhibit the more significant pathology. Haemodynamic and metabolic factors both alone and through the activation of a common pathway contribute to the characteristic dysfunction observed in diabetic vasculopathy. The haemodynamic abnormalities in type 1 diabetes are characterized by increased systemic blood pressure and altered blood flow with subsequent activation of various vasoactive factors, which can contribute to the maintenance of the haemodynamic alterations and to the development and progression of the microvascular complications. These vasoactive factors include vasoconstrictors such as angiotensin II, and endothelin, as well as vasodilators such as nitric oxide (NO). Systemic hypertension and vasoactive factors independently and in interaction with the metabolic pathway activate intracellular second messengers, nuclear transcription factors and various growth factors which lead to the typical functional and structural alterations of diabetic microvascular complications. Therapeutic strategies involved in the management and prevention of diabetic complications currently include antihypertensive agents, particularly those that interrupt the renin-angiotensin system. Further understanding of the interactions among the vasoactive factors, the intracellular second messengers and the growth factors may help to identify novel strategies to influence the action of the vasoactive factors. These novel therapies, together with specific inhibitors of the metabolic pathway or the common pathway, may provide the possibility of preventing or even reversing the progression of diabetic microvascular complications.
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Affiliation(s)
- Riccardo Candido
- Division of Diabetes, Lipoproteins and Metabolism, Baker Heart Research Institute, Melbourne, Victoria, Australia
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13
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Dragović T. [Effect of metabolic control on the onset and development of renal lesions in diabetes mellitus]. VOJNOSANIT PREGL 2002; 59:293-7. [PMID: 12132244 DOI: 10.2298/vsp0203293d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Tamara Dragović
- Vojnomedicinska akademija, Klinika za endokrinologiju, Beograd
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14
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Fabris B, Candido R, Carraro M, Fior F, Artero M, Zennaro C, Cattin MR, Fiorotto A, Bortoletto M, Millevoi C, Bardelli M, Faccini L, Carretta R. Modulation of incipient glomerular lesions in experimental diabetic nephropathy by hypotensive and subhypotensive dosages of an ACE inhibitor. Diabetes 2001; 50:2619-24. [PMID: 11679443 DOI: 10.2337/diabetes.50.11.2619] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
A glomerular permeability defect occurs early in the course of type 1 diabetes and precedes the onset of microalbuminuria and renal morphological changes. Recently, ACE inhibitors have been shown to prevent loss of glomerular membrane permselective function, but the mechanism of this nephroprotective effect is still being debated. The objective of the present study was to evaluate the effects of hypotensive and subhypotensive dosages of the ACE inhibitor quinapril ex vivo and of its active metabolite quinaprilat in vitro on the glomerular albumin permeability (P(alb)) defect in the early phases of experimental diabetes. For the ex vivo study, six groups of male Wistar rats were evaluated for 4 weeks. One group served as a nondiabetic control (C); the other five groups were rendered diabetic and included untreated diabetic rats (D) and diabetic rats receiving quinapril at the dosages of 5 (DQ1), 2.5 (DQ2), 1.25 (DQ3), and 0.625 (DQ4) mg. kg(-1). day(-1). Dosage-dependent effects of quinapril on systolic blood pressure and the glomerular filtration rate were observed. In contrast, control of P(alb) in isolated glomeruli exposed to oncotic gradients, proteinuria, and glomerular and tubular hypertrophy was obtained with subhypotensive dosages (DQ3 and DQ4 groups) of the ACE inhibitor. In the in vitro study, quinaprilat reduced P(alb) significantly in concentration ranges from 10(-6) to 10(-14) mol/l compared with results in control glomeruli. The effect on P(alb) may have occurred by mechanisms different from kidney ACE inhibitor. These study results indicated that ACE inhibitor treatment prevents the early onset of the P(alb) defect in experimental diabetes. This effect seemed to occur independently of systemic or glomerular hemodynamic changes and, at least partially, from kidney ACE inhibition.
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Affiliation(s)
- B Fabris
- Department of Medicina Clinica and Neurologia, University of Trieste, Italy.
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