Karin Jandeleit-Dahm
Research interests
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InterestsDiabetes, Diabetes Complications, Hypertension, Type 1 Diabetes Mellitus, Experimental Diabetes Mellitus
Publications
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The renoprotective actions of peroxisome proliferator-activated receptors agonists in diabetes.
PPAR research. 01/2012; 2012:456529.
Pharmaceutical agonists of peroxisome proliferator-activated receptors (PPARs) are widely used in the management of type 2 diabetes, chiefly as lipid-lowering agents and oral hypoglycaemic agents. Although most of the focus has been placed on their cardiovascular effects, both positive and negative,... [more] Pharmaceutical agonists of peroxisome proliferator-activated receptors (PPARs) are widely used in the management of type 2 diabetes, chiefly as lipid-lowering agents and oral hypoglycaemic agents. Although most of the focus has been placed on their cardiovascular effects, both positive and negative, these agents also have significant renoprotective actions in the diabetic kidney. Over and above action on metabolic control and effects on blood pressure, PPAR agonists also appear to have independent effects on a number of critical pathways that are implicated in the development and progression of diabetic kidney disease, including oxidative stress, inflammation, hypertrophy, and podocyte function. This review will examine these direct and indirect actions of PPAR agonists in the diabetic kidney and explore recent findings of clinical trials of PPAR agonists in patients with diabetes.
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3.96Impact points
The endothelin system and endothelin receptor antagonists.
Current opinion in nephrology and hypertension. 01/2012; 21(1):66-71.
There is increasing evidence that endothelin receptor blockade and, in particular, ET(A) receptor blockade not only confers protection against proteinuric renal disease in diabetes but also confers vasculoprotection. Recent clinical trials using ET(A) receptor blockade in treating proteinuria and ch... [more] There is increasing evidence that endothelin receptor blockade and, in particular, ET(A) receptor blockade not only confers protection against proteinuric renal disease in diabetes but also confers vasculoprotection. Recent clinical trials using ET(A) receptor blockade in treating proteinuria and chronic kidney disease as well as atherosclerosis show great promise; however, adverse effects are still problematic. Endothelin receptor blockade is associated with a significant attenuation of proteinuria and these effects are mediated in part via inhibition of inflammatory and oxidative stress related pathways as well profibrotic pathways. The addition of ET(A) receptor blockade to currently established therapies such as angiotensin-converting enzyme inhibitors or angiotensin receptor blockers may result in additional or synergistic renoprotection and vasculoprotection in hypertension and, in particular, in the context of diabetes.
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7.69Impact points
Suppression of microRNA-29 Expression by TGF-β1 Promotes Collagen Expression and Renal Fibrosis.
Journal of the American Society of Nephrology : JASN. 11/2011; 23(2):252-65.
Synthesis and deposition of extracellular matrix (ECM) within the glomerulus and interstitium characterizes renal fibrosis, but the mechanisms underlying this process are incompletely understood. The profibrotic cytokine TGF-β1 modulates the expression of certain microRNAs (miRNAs), suggesting that ... [more] Synthesis and deposition of extracellular matrix (ECM) within the glomerulus and interstitium characterizes renal fibrosis, but the mechanisms underlying this process are incompletely understood. The profibrotic cytokine TGF-β1 modulates the expression of certain microRNAs (miRNAs), suggesting that miRNAs may have a role in the pathogenesis of renal fibrosis. Here, we exposed proximal tubular cells, primary mesangial cells, and podocytes to TGF-β1 to examine its effect on miRNAs and subsequent collagen synthesis. TGF-β1 reduced expression of the miR-29a/b/c/family, which targets collagen gene expression, and increased expression of ECM proteins. In both resting and TGF-β1-treated cells, ectopic expression of miR-29 repressed the expression of collagens I and IV at both the mRNA and protein levels by targeting the 3'untranslated region of these genes. Furthermore, we observed low levels of miR-29 in three models of renal fibrosis representing early and advanced stages of disease. Administration of the Rho-associated kinase inhibitor fasudil prevented renal fibrosis and restored expression of miR-29. Taken together, these data suggest that TGF-β1 inhibits expression of the miR-29 family, thereby promoting expression of ECM components. Pharmacologic modulation of these miRNAs may have therapeutic potential for progressive renal fibrosis.
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3.98Impact points
RAGE biology, atherosclerosis and diabetes.
Clinical science (London, England : 1979). 07/2011; 121(2):43-55.
Diabetes is characterized by accelerated atherosclerosis with widely distributed vascular lesions. An important mechanism by which hyperglycaemia contributes to vascular injury is through the extensive intracellular and extracellular formation of AGEs (advanced glycation end products). AGEs represen... [more] Diabetes is characterized by accelerated atherosclerosis with widely distributed vascular lesions. An important mechanism by which hyperglycaemia contributes to vascular injury is through the extensive intracellular and extracellular formation of AGEs (advanced glycation end products). AGEs represent a heterogeneous group of proteins, lipids and nucleic acids, irreversibly cross-linked with reducing sugars. AGEs are implicated in the atherosclerotic process, either directly or via receptor-mediated mechanisms, the most extensively studied receptor being RAGE (receptor for AGEs). The AGE-RAGE interaction alters cellular signalling, promotes gene expression and enhances the release of pro-inflammatory molecules. It elicits the generation of oxidative stress in numerous cell types. The importance of the AGE-RAGE interaction and downstream pathways leading to injurious effects as a result of chronic hyperglycaemia in the development, progression and instability of diabetic atherosclerotic lesions has been amply demonstrated in animal studies. Moreover, the deleterious link of AGEs with diabetic vascular complications has been suggested in many human studies. In the present review, our current understanding of their role as an important mediator of vascular injury through the various stages of atherosclerosis in diabetes will be reviewed and critically assessed.
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2.87Impact points
Large artery biomechanics and diastolic dysfunctionin patients with Type 2 diabetes.
Diabetic medicine : a journal of the British Diabetic Association. 01/2011; 28(1):54-60.
To comprehensively characterize large artery biomechanical properties and examine their relationship to cardiac function in patients with Type 2 diabetes mellitus (DM). Fifty-five individuals with Type 2 DM were compared with 66 age- and sex-matched healthy control subjects. Arterial biomechanical p... [more] To comprehensively characterize large artery biomechanical properties and examine their relationship to cardiac function in patients with Type 2 diabetes mellitus (DM). Fifty-five individuals with Type 2 DM were compared with 66 age- and sex-matched healthy control subjects. Arterial biomechanical properties were assessed by systemic arterial compliance (SAC; two-element Windkessel model), carotid-femoral pulse wave velocity (PWVc-f), femoral-dorsalis pedis pulse wave velocity (PWVf-d) and carotid augmentation index. Cardiac structure and function were assessed by echocardiography. Individuals with Type 2 DM had lower SAC and higher PWVc-f when compared with the healthy population. The PWVc-f was significantly lower than the PWVf-d in control individuals, but this difference was not evident in individuals with Type 2 DM due to higher PWVc-f. Augmentation index was similar in both groups, but the time to the first systolic inflection (time to reflection) was shorter in the individuals with Type 2 DM. The individuals with Type 2 DM had a greater prevalence of diastolic abnormalities when compared with the control group. Arterial stiffness indices, including SAC and pulse pressure, correlated with left ventricular filling pressure (defined as peak velocity during early diastolic filling divided by the velocity of movement of the mitral valve annulus in early diastole; r = -0.33 and 0.36 respectively. Patients with Type 2 DM on standard medication showed preferential stiffening of the large central arteries. However, carotid augmentation index was not different between the two groups and is therefore not a reliable indicator of large artery stiffening in this patient group. Diastolic dysfunction, present in a significant proportion of this population with Type 2 DM, was closely associated with arterial stiffening, suggesting a common aetiology.
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8.51Impact points
Antiatherosclerotic and renoprotective effects of ebselen in the diabetic apolipoprotein E/GPx1-double knockout mouse.
Diabetes. 12/2010; 59(12):3198-207.
To investigate the effect of the GPx1-mimetic ebselen on diabetes-associated atherosclerosis and renal injury in a model of increased oxidative stress. The study was performed using diabetic apolipoprotein E/GPx1 (ApoE(-/-)GPx1(-/-))-double knockout (dKO) mice, a model combining hyperlipidemia and h... [more] To investigate the effect of the GPx1-mimetic ebselen on diabetes-associated atherosclerosis and renal injury in a model of increased oxidative stress. The study was performed using diabetic apolipoprotein E/GPx1 (ApoE(-/-)GPx1(-/-))-double knockout (dKO) mice, a model combining hyperlipidemia and hyperglycemia with increased oxidative stress. Mice were randomized into two groups, one injected with streptozotocin, the other with vehicle, at 8 weeks of age. Groups were further randomized to receive either ebselen or no treatment for 20 weeks. Ebselen reduced diabetes-associated atherosclerosis in most aortic regions, with the exception of the aortic sinus, and protected dKO mice from renal structural and functional injury. The protective effects of ebselen were associated with a reduction in oxidative stress (hydroperoxides in plasma, 8-isoprostane in urine, nitrotyrosine in the kidney, and 4-hydroxynonenal in the aorta) as well as a reduction in VEGF, CTGF, VCAM-1, MCP-1, and Nox2 after 10 weeks of diabetes in the dKO aorta. Ebselen also significantly reduced the expression of proteins implicated in fibrosis and inflammation in the kidney as well as reducing related key intracellular signaling pathways. Ebselen has an antiatherosclerotic and renoprotective effect in a model of accelerated diabetic complications in the setting of enhanced oxidative stress. Our data suggest that ebselen effectively repletes the lack of GPx1, and indicate that ebselen may be an effective therapeutic for the treatment of diabetes-related atherosclerosis and nephropathy. Furthermore, this study highlights the feasibility of addressing two diabetic complications with one treatment regimen through the unifying approach of targeted antioxidant therapy.
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8.51Impact points
miR-200a Prevents renal fibrogenesis through repression of TGF-β2 expression.
Diabetes. 10/2010; 60(1):280-7.
Progressive fibrosis in the diabetic kidney is driven and sustained by a diverse range of profibrotic factors. This study examines the critical role of microRNAs (miRNAs) in the regulation of the key fibrotic mediators, TGF-β1 and TGF-β2. Rat proximal-tubular epithelial cells (NRK52E) were treated w... [more] Progressive fibrosis in the diabetic kidney is driven and sustained by a diverse range of profibrotic factors. This study examines the critical role of microRNAs (miRNAs) in the regulation of the key fibrotic mediators, TGF-β1 and TGF-β2. Rat proximal-tubular epithelial cells (NRK52E) were treated with TGF-β1 and TGF-β2 for 3 days, and expression of markers of epithelial-to-mesenchymal transition (EMT) and fibrogenesis were assessed by RT-PCR and Western blotting. The expression of miR-141 and miR-200a was also assessed, as was their role as translational repressors of TGF-β signaling. Finally, these pathways were explored in two different mouse models, representing early and advanced diabetic nephropathy. Both TGF-β1 and TGF-β2 induced EMT and fibrogenesis in NRK52E cells. TGF-β1 and TGF-β2 also downregulated expression of miR-200a. The importance of these changes was demonstrated by the finding that ectopic expression miR-200a downregulated smad-3 activity and the expression of matrix proteins and prevented TGF-β-dependent EMT. miR-200a also downregulated the expression of TGF-β2, via direct interaction with the 3' untranslated region of TGF-β2. The renal expression of miR-141 and miR-200a was also reduced in mouse models representing early and advanced kidney disease. miR-200a and miR-141 significantly impact on the development and progression of TGF-β-dependent EMT and fibrosis in vitro and in vivo. These miRNAs appear to be intricately involved in fibrogenesis, both as downstream mediators of TGF-β signaling and as components of feedback regulation, and as such represent important new targets for the prevention of progressive kidney disease in the context of diabetes.
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4.42Impact points
The pleiotropic actions of rosuvastatin confer renal benefits in the diabetic Apo-E knockout mouse.
American journal of physiology. Renal physiology. 09/2010; 299(3):F528-35.
Diabetic nephropathy is a leading cause of end-stage renal disease. Statins may exert renoprotective effects independently of lipid-lowering properties. We investigated the pleiotropic effects of rosuvastatin on renal structure and function in streptozotocin diabetic apolipoprotein-E knockout (Apo-E... [more] Diabetic nephropathy is a leading cause of end-stage renal disease. Statins may exert renoprotective effects independently of lipid-lowering properties. We investigated the pleiotropic effects of rosuvastatin on renal structure and function in streptozotocin diabetic apolipoprotein-E knockout (Apo-E(-/-)) mice, a model of progressive nephropathy in which dyslipidemia is resistant to statin treatment. These effects were compared with those observed with conventional renin-angiotensin system blockade (candesartan) or combined treatment. Nondiabetic and diabetic Apo-E(-/-) mice were randomized to no treatment or treatment with candesartan (2.5 mg/kg), rosuvastatin (5 mg/kg), or their combination per gavage for 20 wk. Urine and blood samples were collected for assessment of albuminuria, creatinine clearance, plasma lipids, glucose, and glycated hemoglobin. Renal sclerosis was analyzed on paraffin-embedded kidney sections stained with periodic acid-Schiff. Renal expression of collagen IV, fibronectin and advanced glycation end products (AGEs), receptor for advanced glycation and products (RAGE), NADPH oxidase 4 (NOX4), and nitrotyrosine was assessed by real-time PCR and/or immunohistochemistry. Diabetes-induced albuminuria was not affected by rosuvastatin and combination treatment but was prevented by candesartan. Diabetes resulted in increased creatinine clearance, which was not modified by the treatments. Rosuvastatin and/or candesartan prevented diabetes-associated renal extracellular matrix accumulation. Rosuvastatin reduced accumulation of AGEs and expression of RAGE, NOX4, and nitrotyrosine. In conclusion, in the diabetic Apo-E(-/-) mouse, rosuvastatin confers renal benefits that are independent of lipid lowering and equivalent or greater to those observed with candesartan. The combination treatment is not superior to monotherapies.
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8.51Impact points
E-cadherin expression is regulated by miR-192/215 by a mechanism that is independent of the profibrotic effects of transforming growth factor-beta.
Diabetes. 07/2010; 59(7):1794-802.
Increased deposition of extracellular matrix (ECM) within the kidney is driven by profibrotic mediators including transforming growth factor-beta (TGF-beta) and connective tissue growth factor (CTGF). We investigated whether some of their effects may be mediated through changes in expression of cert... [more] Increased deposition of extracellular matrix (ECM) within the kidney is driven by profibrotic mediators including transforming growth factor-beta (TGF-beta) and connective tissue growth factor (CTGF). We investigated whether some of their effects may be mediated through changes in expression of certain microRNAs (miRNAs). Proximal tubular cells, primary rat mesangial cells, and human podocytes were analyzed for changes in the expression of key genes, ECM proteins, and miRNA after exposure to TGF-beta (1-10 ng/microl). Tubular cells were also infected with CTGF-adenovirus. Kidneys from diabetic apoE mice were also analyzed for changes in gene expression and miRNA levels. TGF-beta treatment was associated with morphologic and phenotypic changes typical of epithelial-mesenchymal transition (EMT) including increased fibrogenesis in all renal cell types and decreased E-cadherin expression in tubular cells. TGF-beta treatment also modulated the expression of certain miRNAs, including decreased expression of miR-192/215 in tubular cells, mesangial cells, which are also decreased in diabetic kidney. Ectopic expression of miR-192/215 increased E-cadherin levels via repressed translation of ZEB2 mRNA, in the presence and absence of TGF-beta, as demonstrated by a ZEB2 3'-untranslated region luciferase reporter assay. However, ectopic expression of miR-192/215 did not affect the expression of matrix proteins or their induction by TGF-beta. In contrast, CTGF increased miR-192/215 levels, causing a decrease in ZEB2, and consequently increased E-cadherin mRNA. These data demonstrate the linking role of miRNA-192/215 and ZEB2 in TGF-beta/CTGF-mediated changes in E-cadherin expression. These changes appear to occur independently of augmentation of matrix protein synthesis, suggesting that a multistep EMT program is not necessary for fibrogenesis to occur.
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Cardiovascular disease: what's all the AGE/RAGE about?
Cardiovascular & hematological disorders drug targets. 03/2010; 10(1):7-15.
Advanced glycation end-products (AGEs) are involved in mediating the effects of hyperglycaemia in diabetes. The most important receptor for AGEs is the receptor for advanced glycation end-products (RAGE). Binding of AGEs to RAGE converts transient cellular stimulation into sustained cellular dysfunc... [more] Advanced glycation end-products (AGEs) are involved in mediating the effects of hyperglycaemia in diabetes. The most important receptor for AGEs is the receptor for advanced glycation end-products (RAGE). Binding of AGEs to RAGE converts transient cellular stimulation into sustained cellular dysfunction driven by long-term activation of the pro-inflammatory transcription factor NF-kB. Different splice variants of RAGE exist, including a soluble form that binds to AGEs but lacks the intracellular domain and thus fails to induce signal transduction. In this context, soluble RAGE may act as a therapeutic agent for AGE-induced effects. The balance between the synthesis of sRAGE and full-length RAGE may be an important determinant of AGE-induced dysfunction. An increasing amount of evidence suggests that AGEs either directly or via their interaction with RAGE play a pivotal role in the development and acceleration of atherosclerotic cardiovascular disease. These effects will be summarised in this review, together with the effects of therapeutic strategies targeting AGE/RAGE interactions. These treatments appear to have significant clinical potential, most likely in combination with currently used agents such as inhibitors of the renin-angiotensin system or statins, to reduce the major burden of diabetes, its associated cardiovascular disease.
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12.92Impact points
Post-stroke inhibition of induced NADPH oxidase type 4 prevents oxidative stress and neurodegeneration.
PLoS biology. 01/2010; 8(9).
Ischemic stroke is the second leading cause of death worldwide. Only one moderately effective therapy exists, albeit with contraindications that exclude 90% of the patients. This medical need contrasts with a high failure rate of more than 1,000 pre-clinical drug candidates for stroke therapies. Thu... [more] Ischemic stroke is the second leading cause of death worldwide. Only one moderately effective therapy exists, albeit with contraindications that exclude 90% of the patients. This medical need contrasts with a high failure rate of more than 1,000 pre-clinical drug candidates for stroke therapies. Thus, there is a need for translatable mechanisms of neuroprotection and more rigid thresholds of relevance in pre-clinical stroke models. One such candidate mechanism is oxidative stress. However, antioxidant approaches have failed in clinical trials, and the significant sources of oxidative stress in stroke are unknown. We here identify NADPH oxidase type 4 (NOX4) as a major source of oxidative stress and an effective therapeutic target in acute stroke. Upon ischemia, NOX4 was induced in human and mouse brain. Mice deficient in NOX4 (Nox4(-/-)) of either sex, but not those deficient for NOX1 or NOX2, were largely protected from oxidative stress, blood-brain-barrier leakage, and neuronal apoptosis, after both transient and permanent cerebral ischemia. This effect was independent of age, as elderly mice were equally protected. Restoration of oxidative stress reversed the stroke-protective phenotype in Nox4(-/-) mice. Application of the only validated low-molecular-weight pharmacological NADPH oxidase inhibitor, VAS2870, several hours after ischemia was as protective as deleting NOX4. The extent of neuroprotection was exceptional, resulting in significantly improved long-term neurological functions and reduced mortality. NOX4 therefore represents a major source of oxidative stress and novel class of drug target for stroke therapy.
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6.55Impact points
Angiotensin II subtype 2 receptor blockade and deficiency attenuate the development of atherosclerosis in an apolipoprotein E-deficient mouse model of diabetes.
Diabetologia. 12/2009;
AIMS/HYPOTHESIS: Most of the known actions of angiotensin II have been considered primarily to be the result of angiotensin II subtype 1 receptor activation. However, recent data suggest that the angiotensin II subtype 2 receptor (AT(2)R) may modulate key processes linked to atherosclerosis. The aim... [more] AIMS/HYPOTHESIS: Most of the known actions of angiotensin II have been considered primarily to be the result of angiotensin II subtype 1 receptor activation. However, recent data suggest that the angiotensin II subtype 2 receptor (AT(2)R) may modulate key processes linked to atherosclerosis. The aim of this study was to investigate the role of AT(2)R in diabetes-associated atherosclerosis using pharmacological blockade and genetic deficiency. METHODS: Aortic plaque deposition was assessed in streptozotocin-induced diabetic apolipoprotein E (Apoe) knockout (KO) and At ( 2 ) r (also known as Agtr2)/Apoe double-KO (DKO) mice. Control and diabetic Apoe-KO mice received an AT(2)R antagonist PD123319 (5 mg kg(-1) day(-1)) via osmotic minipump for 20 weeks (n = 7-8 per group). RESULTS: Diabetes was associated with a sixfold increase in plaque area (diabetic Apoe-KO: 12.7 +/- 1.4% vs control Apoe-KO: 2.3 +/- 0.4%, p < 0.001) as well as a significant increase in aortic expression of the gene At ( 2 ) r (also known as Agtr2). The increase in plaque area with diabetes was attenuated in AT(2)R antagonist-treated diabetic Apoe-KO mice (7.1 +/- 0.5%, p < 0.05) and in diabetic At ( 2 ) r/Apoe DKO mice (9.2 +/- 1.3%, p < 0.05). These benefits occurred independently of glycaemic control or BP, and were associated with downregulation of a range of pro-inflammatory cytokines, adhesion molecules, chemokines and various extracellular matrix proteins. CONCLUSIONS/INTERPRETATION: This study provides evidence for AT(2)R playing a role in the development of diabetes-associated atherosclerosis. These findings suggest a potential utility of AT(2)R blockers in the prevention and treatment of diabetic macrovascular complications.
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6.55Impact points
The endothelin receptor antagonist avosentan ameliorates nephropathy and atherosclerosis in diabetic apolipoprotein E knockout mice.
Diabetologia. 10/2009;
AIMS/HYPOTHESIS: There is convincing evidence that the endothelin system contributes to diabetic nephropathy and cardiovascular disease. This study aimed to assess the effects of the non-peptidergic endothelin receptor A (ETA) antagonist avosentan in a mouse model of accelerated diabetic nephropathy... [more] AIMS/HYPOTHESIS: There is convincing evidence that the endothelin system contributes to diabetic nephropathy and cardiovascular disease. This study aimed to assess the effects of the non-peptidergic endothelin receptor A (ETA) antagonist avosentan in a mouse model of accelerated diabetic nephropathy and atherosclerosis in comparison with the ACE inhibitor, quinapril. METHODS: Apolipoprotein E (Apoe) knockout (KO) mice (n = 20 per group, five groups) were randomised to the following groups: non-diabetic controls and streptozotocin-induced diabetic animals gavaged daily for 20 weeks with placebo, avosentan (high dose: 30 mg/kg, or low dose: 10 mg/kg) or quinapril (given in drinking water, 30 mg/kg). RESULTS: BP was unchanged by avosentan treatment but decreased with quinapril treatment. Diabetes-associated albuminuria was significantly attenuated by high-dose avosentan after 10 and 20 weeks of treatment. Diabetic animals showed a decreased creatinine clearance, which was normalised by avosentan treatment. In diabetic mice, high-dose avosentan treatment significantly attenuated the glomerulosclerosis index, mesangial matrix accumulation, glomerular accumulation of the matrix proteins collagen IV, and renal expression of genes encoding connective tissue growth factor, vascular endothelial growth factor, transforming growth factor beta and nuclear factor kappaB (p65 subunit). Furthermore, high-dose avosentan treatment was also associated with reduced expression of the genes for ETA, ETB and angiotensin receptor 1. The renoprotective effects of avosentan were comparable or superior to those observed with quinapril. High-dose avosentan also significantly attenuated diabetes-associated aortic atherosclerosis in Apoe KO mice and reduced macrophage infiltration and aortic nitrotyrosine expression. CONCLUSIONS/INTERPRETATION: This study demonstrates that ETA blockade with avosentan may provide an alternate therapeutic strategy for the treatment of diabetic micro- and macrovascular complications.
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6.55Impact points
Cell division autoantigen 1 plays a profibrotic role by modulating downstream signalling of TGF-beta in a murine diabetic model of atherosclerosis.
Diabetologia. 10/2009;
AIMS/HYPOTHESIS: Excess accumulation of vascular extracellular matrix (ECM) is an important pathological process in cardiovascular diseases including diabetes-associated atherosclerosis. We explored how a recently identified molecule, cell division autoantigen 1 (CDA1), influences the profibrotic TG... [more] AIMS/HYPOTHESIS: Excess accumulation of vascular extracellular matrix (ECM) is an important pathological process in cardiovascular diseases including diabetes-associated atherosclerosis. We explored how a recently identified molecule, cell division autoantigen 1 (CDA1), influences the profibrotic TGF-beta pathway leading to vascular ECM accumulation. METHODS: Expression levels of genes encoding for CDA1, TGF-beta and connective tissue growth factor (CTGF) were examined in aorta from Apoe ( -/- ) mice with or without diabetes. We used retroviral and adenoviral constructs to knockdown or overexpress Tspyl2, the gene encoding CDA1, in mouse vascular smooth muscle cells (VSMCs) with or without TGF-beta treatment in order to demonstrate the role of CDA1 in TGF-beta signalling. RESULTS: In vivo studies indicated that the mRNA levels of CDA1-encoding gene Tspyl2 and protein levels of CDA1 were elevated in the aorta of diabetic Apoe ( -/- ) mice, accompanied by increased levels of Tgf-beta (also known as Tgfb1), Ctgf and ECM accumulation. In vitro studies in vascular cells showed that TGF-beta treatment rapidly increased CDA1 protein levels, which then amplified TGF-beta signalling leading to upregulation of ECM genes. Knockdown of CDA1-encoding gene Tspyl2 to reduce cellular CDA1 level markedly attenuated TGF-beta-stimulated MAD homologue 3 (drosophila; SMAD3) phosphorylation and transcriptional activities. CDA1 overproduction increased and Tspyl2 knockdown decreased expression of TGF-beta receptor type I, TbetarI (also known as Tgfbr1), but not TGF-beta receptor type II, TbetarII (also known as Tgfbr2), providing a mechanism for CDA1's action in modulating TGF-beta signalling. Knockdown of CDA1-encoding gene Tspyl2 also blocked the profibrotic effect of TGF-beta in VSMCs. CONCLUSIONS/INTERPRETATION: CDA1 plays an important role in vascular ECM accumulation by amplifying TGF-beta signalling. This is critical for the profibrotic effect of TGF-beta in the vasculature. CDA1 is therefore a potential target for attenuating vascular ECM accumulation caused by enhanced TGF-beta action, as seen in diabetic atherosclerosis.
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5.23Impact points
IMATINIB INHIBITS VASCULAR SMOOTH MUSCLE PROTEOGLYCAN SYNTHESIS AND REDUCES LDL BINDING IN VITRO AND AORTIC LIPID DEPOSITION IN VIVO.
Journal of cellular and molecular medicine. 09/2009;
ABSTRACT The "response to retention" hypothesis of atherogenesis proposes that proteoglycans bind and retain low density lipoproteins (LDL) in the vessel wall. Platelet derived growth factor (PDGF) is strongly implicated in atherosclerosis and stimulates proteoglycan synthesis. Here we inv... [more] ABSTRACT The "response to retention" hypothesis of atherogenesis proposes that proteoglycans bind and retain low density lipoproteins (LDL) in the vessel wall. Platelet derived growth factor (PDGF) is strongly implicated in atherosclerosis and stimulates proteoglycan synthesis. Here we investigated the action of the PDGF receptor inhibitor imatinib on PDGF-mediated proteoglycan biosynthesis in vitro, lipid deposition in the aortic wall in vivo and the carotid artery ex vivo. In human vSMCs, imatinib inhibited PDGF mediated (35)S-SO(4) incorporation into proteoglycans by 31% (p<0.01) and inhibited PDGF-mediated size increases in both chemically cleaved and xyloside associated glycosaminoglycan (GAG) chains by 19%, p<0.05 and 27%, p<0.05, respectively. Imatinib decreased PDGF stimulation of the 6:4 position sulfation ratio of disaccharides. The half maximal saturation value for LDL binding for proteoglycans from PDGF stimulated cells in the presence of imatinib was approximately 2.5 fold higher than for PDGF treatment alone. In high fat fed ApoE(-/-) mice, imatinib reduced total lipid staining area by approximately 31% (p<0.05). Carotid artery lipid accumulation in imatinib treated mice was also reduced. Furthermore, we demonstrate that imatinib inhibits phosphorylation of tyrosine 857, the autophosphorylation site of the PDGF receptor, in vSMCs. Thus imatinib inhibits GAG synthesis on vascular proteoglycans and reduces LDL binding in vitro and in vivo and this effect is mediated via the PDGF receptor. These findings validate a novel mechanism to prevent cardiac disease.
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6.13Impact points
Direct antiatherosclerotic effects of PPAR agonists.
Current opinion in lipidology. 03/2009; 20(1):24-9.
PURPOSE OF REVIEW: Peroxisome proliferator activated receptors (PPARs) are ligand-dependent transcription factors that mediate a range of important metabolic functions by transactivation, transrepression or corepression of various gene targets. PPAR agonists also have direct antiatherosclerotic effe... [more] PURPOSE OF REVIEW: Peroxisome proliferator activated receptors (PPARs) are ligand-dependent transcription factors that mediate a range of important metabolic functions by transactivation, transrepression or corepression of various gene targets. PPAR agonists also have direct antiatherosclerotic effects, independent of their metabolic effects on glucose and lipid homeostasis. The purpose of this review is to evaluate the currently available evidence for a direct vasculoprotective effect of PPAR agonists. RECENT FINDINGS: Current studies have emphasized PPAR-mediated effects on inflammatory and immune responses, oxidative stress, the renin-angiotensin system and modulation of plaque composition. Furthermore, it has become evident that the relative activation of the different PPAR isoforms and the contribution of transactivation of target genes against transrepression of transcription factors need to be considered when assessing the vasculoprotective effects of PPAR agonists. SUMMARY: It is anticipated that the antiatherosclerotic effects of PPAR agonists observed in experimental studies will translate into reduced cardiovascular events. This promise is yet to be realized in short-to-medium term studies. Given the central role of the PPAR in gene regulation, particularly in metabolic states, it is possible that more targeted modulation of PPAR signalling may hold many rewards for the prevention of atherosclerosis.
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4.29Impact points
Reduced plaque formation induced by rosiglitazone in an STZ-diabetes mouse model of atherosclerosis is associated with downregulation of adhesion molecules.
Atherosclerosis. 08/2008; 199(1):55-64.
Adhesion molecules have been implicated in the development and progression of cardiovascular disease, which is highly prevalent in people with diabetes. Adhesion molecules can mediate adhesion of leukocytes to the endothelium. Furthermore, P-selectin expressed on platelets is able to mediate the adh... [more] Adhesion molecules have been implicated in the development and progression of cardiovascular disease, which is highly prevalent in people with diabetes. Adhesion molecules can mediate adhesion of leukocytes to the endothelium. Furthermore, P-selectin expressed on platelets is able to mediate the adhesion of leukocytes to platelets. In this study, we examine the in-vivo and in-vitro effects of rosiglitazone with particular emphasis on three important adhesion molecules (VCAM-1, ICAM-1 and P-selectin). In the aorta of STZ-diabetic apolipoprotein E-deficient (apoE KO) mice, rosiglitazone significantly reduced both total and arch plaque area. The mechanism for this appeared to be reduced macrophage infiltration into the atherosclerotic plaque which was also associated with reduced mRNA levels for VCAM-1, ICAM-1, MCP-1 and P-selectin in the aorta. In-vitro studies revealed reduced cell adhesion of monocytic cells (THP-1) to fibrinogen and endothelial cells (HUVEC) after incubation with rosiglitazone. Furthermore, the reduction in leukocyte adhesion also correlated with significant reductions in mRNA levels for VCAM-1, ICAM-1 and P-selectin indicating that reduced macrophage infiltration in atherosclerotic plaques may occur as a result of a direct effect of rosiglitazone on adhesion molecules in both monocytes and endothelial cells. Thus, we have shown that rosiglitazone appears to have direct anti-atherosclerotic effects in an animal model of diabetes-associated atherosclerosis which are at least partly due to effects on VCAM-1, ICAM-1, MCP-1 and P-selectin expression which leads to decreased leukocyte adhesion and macrophage infiltration.
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6.55Impact points
The HMG-CoA reductase inhibitor rosuvastatin and the angiotensin receptor antagonist candesartan attenuate atherosclerosis in an apolipoprotein E-deficient mouse model of diabetes via effects on advanced glycation, oxidative stress and inflammation.
Diabetologia. 08/2008;
AIMS/HYPOTHESIS: We evaluated the anti-atherosclerotic effect of the 3-hydroxy-3-methylglutaryl CoA reductase inhibitor, rosuvastatin, and the angiotensin II receptor blocker (ARB), candesartan, alone and in combination, in the streptozotocin-induced diabetic apolipoprotein E-deficient (Apoe (-/-)) ... [more] AIMS/HYPOTHESIS: We evaluated the anti-atherosclerotic effect of the 3-hydroxy-3-methylglutaryl CoA reductase inhibitor, rosuvastatin, and the angiotensin II receptor blocker (ARB), candesartan, alone and in combination, in the streptozotocin-induced diabetic apolipoprotein E-deficient (Apoe (-/-)) mouse. METHODS: Control and streptozotocin-induced diabetic Apoe (-/-) mice received rosuvastatin (5 mg kg(-1) day(-1)), candesartan (2.5 mg kg(-1) day(-1)), dual therapy or no treatment for 20 weeks. Aortic plaque deposition was assessed by Sudan IV staining and subsequent visual quantification. The abundance of proteins was measured using immunohistochemistry. RESULTS: Diabetes was associated with a fourfold increase in total plaque area. Rosuvastatin attenuated plaque area in diabetic mice in the absence of lipid-lowering effects. The anti-atherosclerotic effect of rosuvastatin was comparable to that observed with candesartan. A similar beneficial effect was seen with dual therapy, although it was not superior to monotherapy. Rosuvastatin treatment was associated with attenuated accumulation of AGE and AGE receptor (RAGE) in plaques. Similar beneficial effects on markers of oxidative stress were seen with the ARB and statin. Candesartan was more effective at reducing macrophage accumulation and collagen I abundance in plaques compared with rosuvastatin. The combined effect of candesartan and rosuvastatin was superior in reducing macrophage infiltration, monocyte chemoattractant protein-1 level, vascular AGE accumulation and RAGE abundance in the vascular wall. Furthermore, the combination tended to be more effective in reducing smooth muscle cell infiltration and connective tissue growth factor abundance in plaques. CONCLUSIONS/INTERPRETATION: Rosuvastatin has direct anti-atherosclerotic effects in diabetic macrovascular disease. These effects are independent of effects on lipids and comparable to the effects observed with candesartan.
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8.51Impact points
RAGE DEFICIENCY ATTENUATES THE DEVELOPMENT OF ATHEROSCLEROSIS IN DIABETES.
Diabetes. 06/2008;
Objective: Activation of the Receptor for Advanced Glycation End-products (RAGE) in diabetic vasculature is considered to be a key mediator of atherogenesis. This study examines the effects of deletion of RAGE on the development of atherosclerosis in the diabetic apoE(-/-) model of accelerated ather... [more] Objective: Activation of the Receptor for Advanced Glycation End-products (RAGE) in diabetic vasculature is considered to be a key mediator of atherogenesis. This study examines the effects of deletion of RAGE on the development of atherosclerosis in the diabetic apoE(-/-) model of accelerated atherosclerosis. Research Design and Methods: ApoE(-/-) and RAGE(-/-)/apoE(-/-) double knock-out (KO) mice were rendered diabetic with streptozotozin and followed for 20 weeks, at which time plaque accumulation was assessed by en face analysis. Results: While diabetic apoE(-/-) mice showed increased plaque accumulation (14.9+/-1.7%), diabetic RAGE(-/-)/apoE(-/-) mice had significantly reduced atherosclerotic plaque area (4.9+/-0.4%) to levels not significantly different to control apoE-/- mice (4.3+/-0.4%). These beneficial effects on the vasculature were associated with attenuation of leucocyte recruitment, decreased expression of proinflammatory mediators including the NF-kB subunit p65, VCAM-1, MCP-1, reduced oxidative stress, as reflected by staining for nitrotyrosine and reduced expression of various NADPH oxidase subunits, gp91phox, p47phox and rac-1. Both RAGE and RAGE-ligands, including S100A8/9, HMGB1 and the AGE, carboxymethyllysine (CML) were increased in plaques from diabetic apoE(-/-) mice. Furthermore, the accumulation of AGEs and other ligands to RAGE was reduced in diabetic RAGE(-/-)/apoE(-/-) mice. Conclusions: This study provides evidence for RAGE playing a central role in the development of accelerated atherosclerosis associated with diabetes. These findings emphasize the potential utility of strategies targeting RAGE activation in the prevention and treatment of diabetic macrovascular complications.
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1.94Impact points
The AGE/RAGE axis in diabetes-accelerated atherosclerosis.
Clinical and experimental pharmacology & physiology. 04/2008; 35(3):329-34.
1. There is increasing evidence that advanced glycation end-products (AGEs) and their interaction with the receptor RAGE play a pivotal role in atherosclerosis, in particular in the setting of diabetes. 2. Previous studies have shown that inhibition of AGE accumulation and RAGE expression in diabete... [more] 1. There is increasing evidence that advanced glycation end-products (AGEs) and their interaction with the receptor RAGE play a pivotal role in atherosclerosis, in particular in the setting of diabetes. 2. Previous studies have shown that inhibition of AGE accumulation and RAGE expression in diabetes by either reduction of the formation of AGEs or cross-link breakers was associated with reduced atherosclerosis and renal disease. Advanced glycation end-products bind to RAGE, thereby leading to activation of a range of inflammatory and fibrotic pathways causing tissue injury. Different splice variants of RAGE exist, including a soluble form that lacks the intracellular domain and fails to induce signal transduction. Therapeutic approaches using soluble RAGE as a decoy binding protein for circulating AGE have been effective in preventing externally induced arterial injury and atherosclerosis in the absence and presence of diabetes. 3. In order to delineate the role of RAGE in vascular disease in more detail, it was necessary to create RAGE(-/-) mice, as well as transgenic mice overexpressing RAGE in endothelial cells. It was shown that RAGE overexpression was associated with increased vascular injury, nephropathy and retinopathy. 4. In contrast, RAGE deletion was associated with partial vascular protection, such as reduced neointima formation after arterial denudation, as well as protection from diabetic nephropathy. The present review summarizes the evidence for RAGE being a pro-inflammatory and pro-fibrotic receptor. 5. Further studies are needed to delineate the effect of RAGE deletion and overexpression in diabetic macrovascular disease. Based on these findings, RAGE could be a potential therapeutic target in combating inflammatory vascular diseases, including diabetes-associated atherosclerosis.
Following (8)
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Mandy L Ballinger
Peter MacCallum Cancer Centre -
Peter J Little
RMIT University -
Darren J Kelly
University of Melbourne -
Louise M Burrell
University of Melbourne -
Zemin Cao
Baker IDI Heart and Diabetes Institute
Topics (1)
