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Query: UMLS:C0011881 (diabetic nephropathy)
 10,836 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Renal injury in diabetes mellitus is a major cause of morbidity and mortality. Several manifestations of diabetic nephropathy may be a consequence of altered production and/or response to cytokines or growth factors. Transforming growth factor-beta (TGF-beta) is one such factor because it promotes renal cell hypertrophy and regulates the production of extracellular matrix molecules. In addition, high ambient glucose increases TGF-beta1 mRNA and protein level in cultured proximal tubular cells and glomerular epithelial and mesangial cells. Neutralizing anti-TGF-beta antibodies or antisense TGF-beta1 oligodeoxynucleotides prevents the hypertrophic effects of high glucose and the stimulation of matrix synthesis in renal cells. Several reports have described overexpression of TGF-beta in the glomeruli and tubulointerstitium of experimental and human diabetes mellitus. We recently provided evidence that the kidney in diabetic patients displays net renal production of immunoreactive TGF-beta1, whereas there is net renal extraction in nondiabetic subjects. We also demonstrated that short-term treatment of streptozotocin-diabetic mice with neutralizing monoclonal antibody directed against TGF-beta significantly reduces kidney weight and glomerular hypertrophy, and attenuates the increase in extracellular matrix mRNA levels. The factors that mediate increased renal TGF-beta activity involve hyperglycemia per se and the intermediary action of other potent mediators such as angiotensin II, thromboxane, endothelins, and platelet-derived growth factor.
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PMID:Potential role of TGF-beta in diabetic nephropathy. 952 4

Chronic renal failure may occur in etiologically diverse renal diseases and can be caused by hemodynamic, immunologic and metabolic factors. Initial damage may evoke irreversible scarring, which involves production of a number of proinflammatory and fibrogenic cytokines, including platelet-derived growth factor (PDGF) and transforming growth factor beta (TGF-beta). Connective tissue growth factor (CTGF), a cytokine of the family of growth regulators comprising sef10, cyr61, CTGF and nov, has recently been described in association with scleroderma and other scarring conditions. We investigated CTGF mRNA expression in 65 human renal biopsy specimens of various renal diseases by in situ hybridization. In control human kidney CTFG mRNA was mainly expressed in visceral epithelial cells, parietal epithelial cells, and some interstitial cells. Connective tissue growth factor was strongly up-regulated in the extracapillary and severe mesangial proliferative lesions of crescentic glomerulonephritis, IgA nephropathy, focal and segmental glomerulosclerosis and diabetic nephropathy. An increase in the number of cells expressing CTGF mRNA was observed at sites of chronic tubulointerstitial damage, which correlated with the degree of damage. in the tubulointerstitial area the majority of the CTGF mRNA positive cells coexpressed alpha-smooth muscle actin, and were negative for macrophage markers. Our results indicate that CTGF may be a common growth factor involved in renal fibrosis.
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PMID:Expression of connective tissue growth factor in human renal fibrosis. 955 91

Altered growth of renal cells is one of the early abnormalities detected after the onset of diabetes. Cell culture studies whereby renal cells are exposed to high glucose concentrations have provided a considerable amount of insight into mechanisms of growth. In the glomerular compartment, there is a very early and self-limited proliferation of mesangial cells with subsequent hypertrophy, whereas proximal tubular cells primarily undergo hypertrophy. There is overwhelming evidence from in vivo and cell culture studies that induction of the transforming growth factor-beta (TGF-beta) system mediates the actions of high ambient glucose and that this system is pivotal for the hypertrophy of mesangial and tubular cells. Other factors such as hemodynamic forces, protein glycation products, and several mediators (for example, angiotensin II, endothelin-1, thromboxane, and platelet-derived growth factor) may further amplify the synthesis of TGF-beta and/or the expression of its receptors in the diabetic state. Cellular hypertrophy can be characterized by cell cycle arrest in the G1 phase. The molecular mechanism arresting mesangial cells in the G1 phase of the cell cycle is the induction of cyclin-dependent kinase (CdK) inhibitors such as p27Kip1 and p21, which bind to and inactivate cyclin-CdK complexes responsible for G1-phase exit. High-glucose-induced activation of protein kinase C and stimulated TGF-beta expression appear to be essential for stimulated expression of p27Kip1. In addition, a decreased turnover of protein caused by the inhibition of proteases contributes to hypertrophy. The development of irreversible renal changes in diabetes mellitus such as glomerulosclerosis and tubulointerstitial fibrosis is always preceded by the early hypertrophic processes in the glomerular and the tubular compartments. It may still be debated whether diabetic renal hypertrophy will inevitably lead to irreversible fibrotic changes in the absence of other factors such as altered intraglomerular hemodynamics and genetic predisposition. Nevertheless, understanding cellular growth on a molecular level may help design a novel therapeutic approach to prevent or treat diabetic nephropathy effectively.
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PMID:Molecular mechanisms of diabetic renal hypertrophy. 1043 77

Diabetes is now the most common cause of kidney failure. The pathogenesis of diabetic nephropathy in both type 1 and type 2 diabetes, however, is still incompletely understood. Two mechanisms postulated to contribute to the pathogenesis of progressive diabetic nephropathy are glomerular cell proliferation and glomerular visceral epithelial cell or podocyte injury. The aim of the current study was to determine whether the aggravation of mesangial cell injury or podocyte injury in isolation would induce progressive diabetic nephropathy. Specifically, we examined whether the administration of either platelet-derived growth factor (PDGF) or basic fibroblast growth factor (bFGF) in sub-nephritogenic doses might lead to an aggravation of kidney structural changes associated with hyperglycemia, resulting in progressive kidney damage in the Goto Kakizaki (GK) rat, which is a genetic model of non-obese non-insulin-dependent diabetes mellitus (NIDDM), in which progressive kidney disease does not develop spontaneously. The results demonstrate that the administration of PDGF to hyperglycemic GK rats led to acute mesangial cell proliferation and activation as assessed by 5-bromo-2'-deoxyuridine-positive nuclei and immunostaining for alpha-smooth muscle actin. Despite acute mesangial cell activation and proliferation, PDGF treatment had no long-term effect on either kidney structure or function. Similarly, treatment of GK rats with bFGF, despite the augmentation of podocyte injury as demonstrated by de novo expression of glomerular desmin expression, did not lead to the development of progressive diabetic nephropathy. In summary, the data in the current manuscript suggest that the additive effect of hyperglycemia and superimposed isolated mesangial cell or podocyte injury does not lead to progressive diabetic nephropathy. This further emphasises the multifactorial nature of the pathogenesis of progressive diabetic nephropathy.
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PMID:Augmentation of kidney injury by basic fibroblast growth factor or platelet-derived growth factor does not induce progressive diabetic nephropathy in the Goto Kakizaki model of non-insulin-dependent diabetes. 1048 16

Angiotensin II plays a central role in the regulation of systemic arterial pressure through its systemic synthesis via the renin-angiotensin-aldosterone cascade. It acts directly on vascular smooth muscle as a potent vasoconstrictor. In addition, it affects cardiac contractility and heart rate through its action on the sympathetic nervous system. Angiotensin II also alters renal sodium and water absorption through its ability to stimulate the zona glomerulosa cells of the adrenal cortex to synthesize and secrete aldosterone. Furthermore, it enhances thirst and stimulates the secretion of the antidiuretic hormone. Consequently, angiotensin II plays a critical role in both the acute and chronic regulation of blood pressure through its systemic endocrine regulation. A potent neurohormone that regulates systemic arterial pressure, angiotensin II also affects vascular structure and function via paracrine and autocrine effects of local tissue-based synthesis. This alternate pathway of angiotensin II production is catalyzed in tissues via enzymes such as cathepsin G, chymostatin-sensitive angiotensin II-generating enzyme, and chymase. Intratissue formation of angiotensin II plays a critical role in cardiovascular remodeling. Upregulation of these alternate pathways may occur through stretch, stress, and turbulence within the blood vessel. Similar processes within the myocardium and glomeruli of the kidney may also lead to restructuring in these target organs, with consequent organ dysfunction. Additionally, angiotensin II may increase receptor density and sensitivity for other factors that modulate growth of vascular smooth muscle, such as fibroblast growth factor, transforming growth factor beta-1, platelet-derived growth factor, and insulin-like growth factors. Atherosclerosis may also be related, in part, to excessive angiotensin II effect on the vessel wall, which causes smooth muscle cell growth and migration. It also activates macrophages and increases platelet aggregation. Angiotensin II stimulates plasminogen activator inhibitor 1 and directly causes endothelial dysfunction. Other postulated effects of angiotensin II on vascular structure that could promote atherogenesis include inhibition of apoptosis, increase in oxidative stress, promotion of leukocyte adhesion and migration, and stimulation of thrombosis. Inhibition of angiotensin II synthesis with an angiotensin-converting enzyme inhibitor has been demonstrated to be beneficial in modifying human disease progression. This is clearly apparent in clinical trials involving patients with diabetic nephropathy, postmyocardial infarction, or advanced degrees of systolic heart failure. Thus, angiotensin II is an excellent target for pharmacologic blockade. Not only does it play a pivotal role in both the acute and chronic regulation of systemic arterial pressure, but it also is an important modulator of cardiovascular structure and function and may be specifically involved in disease progression. Modification of angiotensin II effect may therefore serve a dual purpose. Not only will blood pressure reduction occur with less stretch, stress, and turbulence of the vascular wall, but there will also be less stimulation, either directly or indirectly, for restructuring and remodeling of the cardiovascular tree.
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PMID:The renin-angiotensin-aldosterone system: a specific target for hypertension management. 1061 73

Glomerular proteinuria is a risk factor for progression of chronic renal failure and contributes to renal interstitial fibrosis. In experimental diabetic glomerular sclerosis, there is translocation of high-molecular-weight growth factors, namely, hepatocyte growth factor (HGF) and transforming growth factor (TGF)-beta, from plasma into tubular fluid, both of which act on tubular cells through apical membrane receptors. In the present studies, the hypothesis is examined that ultrafiltered HGF and TGF-beta induce increased expression of extracellular matrix (ECM) proteins directly in tubular cells, or induce increased expression of cytokines that may act on interstitial myofibroblasts. Incubation of cultured tubular cells with recombinant human (rh) TGF-beta modestly raises expression of collagen type III, but rhHGF dose dependently blocks expression of this ECM protein. Both growth factors raise fibronectin expression up to fourfold and increase expression of platelet-derived growth factor (PDGF)-BB up to sixfold, but not of fibroblast growth factor-2. Pooled, diluted glomerular ultrafiltrate that had been collected by nephron micropuncture from rats with diabetic nephropathy (24-30 wk) also raises expression of fibronectin as well as PDGF-BB in proximal tubular cells. In the presence of neutralizing antibodies that block actions of HGF and TGF-beta, diabetic rat glomerular ultrafiltrate fails to increase tubular cell PDGF-BB expression. In NRK-49F renal interstitial myofibroblasts, rhPDGF-BB, in turn, raises the expression of collagen type III but not type I or fibronectin. The findings provide evidence for ultrafiltered HGF and TGF-beta to contribute to interstitial accumulation of ECM proteins by direct effects on tubular cells as well as indirect mechanisms, via PDGF-BB and its action on myofibroblasts. These events may be important mechanisms of proteinuria-induced renal interstitial fibrosis and accelerated progression of chronic renal failure in diabetic nephropathy and perhaps other proteinuric glomerular diseases.
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PMID:Growth factor ultrafiltration in experimental diabetic nephropathy contributes to interstitial fibrosis. 1075 Dec 15

Platelet-derived growth factor (PDGF) was found to contribute to the pathophysiological process in the development and progression of glomerulosclerosis characterized by mesangial cell proliferation and accumulation of extracellular matrix. To examine the role of PDGF in the development of diabetic nephropathy, we conducted immunohistochemical analysis for PDGF B-chain (PDGF-B) and PDGF beta-receptor (PDGFR-beta) in the glomeruli of streptozotocin-induced diabetic rats. At 2, 4, and 12 weeks after the onset of diabetes, the expression of PDGF-B in glomeruli of diabetic rats was increased significantly as compared to control or diabetic rats treated with insulin. Similar changes were observed on PDGFR-beta immunostaining. The immunostaining of mirror sections revealed the existence of PDGF-B or PDGFR-beta not only in mesangial cells but also in visceral epithelial cells. Glomerular volume was significantly increased in diabetes. This early glomerular abnormality was prevented by an inhibition of PDGF system with trapidil as well as by the treatment of insulin. Our results suggest that the activation of the PDGF system in glomerular cells might play an important role in the development of early glomerular lesion in diabetes.
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PMID:Immunohistochemical characterization of glomerular PDGF B-chain and PDGF beta-receptor expression in diabetic rats. 1080 45

P:eroxisome proliferator-activated receptor-gamma (PPARgamma) is a novel nuclear receptor, which enhances insulin-mediated glucose uptake. Ligands to PPARgamma are currently used as therapy for type II diabetes. Using Western blot analysis, RNase protection assay, and immunostaining, we identified the presence of PPARgamma message and protein in cultured primary rat mesangial cells. Electrophoretic mobility of a labeled PPARgamma response element (PPRE) was retarded in the presence of mesangial cell nuclear extract, suggesting that PPARgamma is functional in these cells. The addition of unlabeled PPRE efficiently competed away the PPARgamma-PPRE protein complex, confirming specificity of binding of the PPARgamma to the PPRE. PPARgamma ligands rosiglitazone (1 to 10 micromol/L) and troglitazone (1 to 10 micromol/L) inhibited platelet-derived growth factor-induced DNA synthesis, measured as bromodeoxyuridine incorporation (P<0.01). This inhibition was dose dependent. When administered in antidiabetic doses to streptozotocin-induced diabetic rats, troglitazone substantially normalized albumin excretion at 3 months (from 687.1 to 137.6 microgram urinary albumin/mg creatinine, P:<0.05) but did not affect hyperglycemia or blood pressure in this model. This treatment also decreased glomerular plasminogen activator inhibitor-1 (PAI-1) expression. These data suggest that PPARgamma activation may directly attenuate diabetic glomerular disease, possibly by inhibiting mesangial growth, which occurs early in the process of diabetic nephropathy, or by inhibiting PAI-1 expression. PAI-1 inhibits the activation of plasmin and matrix metalloproteinase, which degrade extracellular matrix in the glomerulus. Excess glomerular PAI-1 allows the accumulation of extracellular matrix, leading to glomerulosclerosis. These results have therapeutic implications for diabetic nephropathy as well as for proliferative mesangial diseases of the kidney.
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PMID:Expression and function of peroxisome proliferator-activated receptor-gamma in mesangial cells. 1123 Mar 63

Profibrotic cytokines and the formation of advanced-glycation end products (AGE) have both been implicated in the pathogenesis of glomerulosclerosis in diabetic kidney disease. However, tubulointerstitial pathology is also an important determinant of progressive renal dysfunction in diabetic nephropathy. This study sought to investigate the expression of profibrotic growth factors and matrix deposition in the glomerulus and the tubulointerstitium and to examine the effect of blocking AGE formation in experimental diabetic nephropathy. Thirty-six male Sprague-Dawley rats were randomized into control and diabetic groups. Diabetes was induced in 24 rats by streptozotocin. Twelve diabetic rats were further randomized to receive the inhibitor of AGE formation, aminoguanidine (1 g/l drinking water). At 6 mo, experimental diabetes was associated with a three-fold increase in expression of transforming growth factor (TGF)-beta1 (P < 0.01 versus control) and five-fold increase in platelet-derived growth factor (PDGF)-B gene expression (P < 0.01 versus control) in the tubulointerstitium. In situ hybridization demonstrated a diffuse increase in both TGF-beta1 and PDGF-B mRNA in renal tubules. Aminoguanidine attenuated not only the overexpression of TGF-beta1 and PDGF-B but also reduced type IV collagen deposition in diabetic rats (P < 0.05). TGF-beta1 and PDGF mRNA within glomeruli were also similarly increased with diabetes and attenuated with aminoguanidine. The observed beneficial effects of aminoguanidine on the tubulointerstitium in experimental diabetes suggest that AGE-mediated expression of profibrotic cytokines may contribute to tubulointerstitial injury and the pathogenesis of diabetic nephropathy.
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PMID:Aminoguanidine ameliorates overexpression of prosclerotic growth factors and collagen deposition in experimental diabetic nephropathy. 1156 8

Mitogen-activated protein kinase (MAPK) p38 is activated in response to stress stimuli and growth factors relevant to the pathogenesis of diabetic nephropathy. We postulated that mesangial cells exposed to high glucose and to endothelin-1 (ET-1), angiotensin II (ANG II), and platelet-derived growth factor (PDGF) demonstrate enhanced p38 activity and subsequent activation of the cAMP responsive element binding (CREB) transcription factor. Primary rat mesangial cells exposed to 5.6 (NG) or 30 mM glucose (HG) or NG plus 24.4 mM sorbitol (osmotic control) for < or = 4 days were acutely stimulated with ET-1, ANG II, or PDGF. After 3 days of HG, p38 phosphorylation and kinase activity increased twofold (P < 0.05 vs. NG, n = 5). No change in p38 activity was observed with sorbitol. In HG, activation of p38 by ET-1, ANG II, or PDGF was enhanced compared with NG and was protein kinase C (PKC) independent. In HG, CREB phosphorylation in response to ET-1, ANG II, and PDGF stimulation was enhanced compared with NG and was abolished by p38 inhibition with SB202190. To conclude, in HG, mesangial cell p38 is activated, which in turn stimulates CREB phosphorylation. Furthermore, in HG, mesangial cell p38 responsiveness to ET-1, ANG II, and PDGF and consequent CREB phosphorylation are enhanced through a PKC-independent pathway, which may contribute to the pathogenesis of diabetic nephropathy.
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PMID:High glucose-enhanced activation of mesangial cell p38 MAPK by ET-1, ANG II, and platelet-derived growth factor. 1173 97


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