Alessandra Dei Cas

Podocyte-Specific Expression of Angiopoietin-2 Causes Proteinuria and Apoptosis of Glomerular Endothelia

Angiopoietin-2 (Ang-2) modulates embryonic vascular differentiation primarily by inhibiting the antiapoptotic effects of Ang-1 on endothelia that express the Tie-2 receptor. Ang-2 is transiently expressed by developing glomeruli but is downregulated with normal maturation. Glomerular Ang-2 expression is, however, markedly upregulated in animal models of diabetic nephropathy and glomerulonephritis, both leading causes of human chronic renal disease, affecting 10% of the world population. It was hypothesized that Ang-2 might have significant roles in the pathobiology of glomerular disease. Mice with inducible podocyte-specific Ang-2 overexpression were generated. When the transgene was induced in adults for up to 10 wk, mice had significant increases in both albuminuria and glomerular endothelial apoptosis, with significant decreases of both vascular endothelial growth factor-A and nephrin proteins, critical for maintenance of glomerular endothelia and filtration barrier functional integrity, respectively. There was, however, no significant change of systemic BP, creatinine clearance, or markers of renal fibrosis, and podocytes appeared structurally intact. In kidneys of young animals in which Ang-2 had been upregulated during organogenesis, increased apoptosis occurred in just-formed glomeruli. In vitro, short-term exposure of isolated wild-type murine glomeruli to exogenous Ang-2 led to decreased levels of vascular endothelial growth factor-A protein. These novel results provide insight into molecular mechanisms underlying proteinuric disorders, highlight potentially complex interactions between subsets of glomerular cells, and emphasize how a vascular growth factor that has critical roles in normal development may be harmful when re-expressed in the context of adult disease.

Impact of diabetes on epidemiology, treatment, and outcomes of patients with heart failure

The prevalence of patients with concomitant heart failure (HF) and diabetes mellitus (DM) continues to increase with the general aging of the population. In patients with chronic HF, prevalence of DM is 24% compared with 40% in those hospitalized with worsening HF. Patients with concomitant HF and DM have diverse pathophysiologic, metabolic, and neurohormonal abnormalities that potentially contribute to worse outcomes than those without comorbid DM. In addition, although stable HF outpatients with DM show responses that are similar to those of patients without DM undergoing evidence-based therapies, it is unclear whether hospitalized HF patients with DM will respond similarly to novel investigational therapies. These data support the need to re-evaluate the epidemiology, pathophysiology, and therapy of HF patients with concomitant DM. This paper discusses the role of DM in HF patients and underscores the potential need for the development of targeted therapies.

Inducible Overexpression of sFlt-1 in Podocytes Ameliorates Glomerulopathy in Diabetic Mice

OBJECTIVE—Podocyte-specific, doxycycline (DOX)-inducible overexpression of soluble vascular endothelial growth factor (VEGF) receptor-1 (sFlt-1) in adult mice was used to investigate the role of the VEGF-A/VEGF receptor (VEGFR) system in diabetic glomerulopathy. RESEARCH DESIGN AND METHODS—We studied nondiabetic and diabetic transgenic mice and wild-type controls treated with vehicle (VEH) or DOX for 10 weeks. Glycemia was measured by a glucose-oxidase method and blood pressure by a noninvasive technique. sFlt-1, VEGF-A, VEGFR2, and nephrin protein expression in renal cortex were determined by Western immunoblotting; urine sFlt-1, urine free VEGF-A, and albuminuria by enzyme-linked immunosorbent assay; glomerular ultrastructure by electron microscopy; and VEGFR1 and VEGFR2 cellular localization with Immunogold techniques. RESULTS—Nondiabetic DOX-treated transgenic mice showed a twofold increase in cortex sFlt-1 expression and a fourfold increase in sFlt-1 urine excretion (P < 0.001). Urine free VEGF-A was decreased by 50%, and cortex VEGF-A expression was upregulated by 30% (P < 0.04). VEGFR2 expression was unchanged, whereas its activation was reduced in DOX-treated transgenic mice (P < 0.02). Albuminuria and glomerular morphology were similar among groups. DOX-treated transgenic diabetic mice showed a 60% increase in 24-h urine sFlt-1 excretion and an ∼70% decrease in urine free VEGF-A compared with VEH-treated diabetic mice (P < 0.04) and had lower urine albumin excretion at 10 weeks than VEH-treated diabetic (d) mice: d-VEH vs. d-DOX, geometric mean (95% CI), 117.5 (69–199) vs. 43 (26.8–69) μg/24 h (P = 0.003). Diabetes-induced mesangial expansion, glomerular basement membrane thickening, podocyte foot-process fusion, and transforming growth factor-β1 expression were ameliorated in DOX-treated diabetic animals (P < 0.05). Diabetes-induced VEGF-A and nephrin expression were not affected in DOX-treated mice. CONCLUSIONS—Podocyte-specific sFlt-1 overexpression ameliorates diabetic glomerular injury, implicating VEGF-A in the pathogenesis of this complication.

Effect of Spironolactone on Left Ventricular Ejection Fraction and Volumes in Patients With Class I or II Heart Failure

The beneficial effects of spironolactone in chronic heart failure (HF) have been demonstrated in patients with New York Heart Association (NYHA) class III to IV HF. This study examined the effect of spironolactone on left ventricular (LV) function and functional capacity of patients with mild to moderate HF (NYHA class I to II). One hundred sixty-eight patients with NYHA class I to II HF and LV ejection fraction ≤40% were randomized to spironolactone or placebo and assessed by echocardiography, gated single-photon emission computed tomography, technetium-99m sestamibi single-photon emission computed tomographic radionuclide ventriculography, and cardiopulmonary exercise testing at baseline and after 6 months of treatment. In the spironolactone group LV ejection fraction increased from 35.2 ± 0.7% to 39.1 ± 3.5% (p <0.001), with a decrease in LV end-diastolic and end-systolic volumes and myocardial mass and an improvement in LV diastolic filling pattern. Cardiopulmonary exercise testing parameters did not change. In conclusion, administration of spironolactone to patients with NYHA class I to II HF has beneficial effects on LV remodeling and diastolic function.

Nebivolol: Haemodynamic Effects and Clinical Significance of Combined β-Blockade and Nitric Oxide Release

Nebivolol is a third-generation beta-adrenergic receptor antagonist (beta-blocker) with high selectivity for beta(1)-adrenergic receptors. In addition, it causes vasodilatation via interaction with the endothelial L-arginine/nitric oxide (NO) pathway. This dual mechanism of action underlies many of the haemodynamic properties of nebivolol, which include reductions in heart rate and blood pressure (BP), and improvements in systolic and diastolic function. With respect to BP lowering, the NO-mediated effects cause a reduction in peripheral vascular resistance and an increase in stroke volume with preservation of cardiac output. Flow-mediated dilatation and coronary flow reserve are also increased during nebivolol administration. Other haemodynamic effects include beneficial effects on pulmonary artery pressure, pulmonary wedge pressure, exercise capacity and left ventricular ejection fraction. In addition, nebivolol does not appear to have adverse effects on lipid metabolism and insulin sensitivity like traditional beta-blockers. The documented beneficial haemodynamic effects of nebivolol are translated into improved clinical outcomes in patients with hypertension or heart failure. In patients with hypertension, the incidence of bradycardia with nebivolol is often lower than that with other currently available beta-blockers. This, along with peripheral vasodilatation and NO-induced benefits such as antioxidant activity and reversal of endothelial dysfunction, should facilitate better protection from cardiovascular events. In addition, nebivolol has shown an improved tolerability profile, particularly with respect to events commonly associated with beta-blockers, such as fatigue and sexual dysfunction. Data from SENIORS (Study of the Effects of Nebivolol Intervention on Outcomes and Rehospitalization in Seniors with Heart Failure) showed that significantly fewer nebivolol versus placebo recipients experienced the primary endpoint of all-cause mortality or cardiovascular hospitalization. The benefits of nebivolol therapy were shown to be cost effective. Thus, nebivolol is an effective and well tolerated agent with benefits over and above those of traditional beta-blockade because of its effects on NO release, which give it unique haemodynamic effects, cardioprotective activity and a good tolerability profile.

Mechanical forces and TGFbeta1 reduce podocyte adhesion through alpha3beta1 integrin downregulation.

BACKGROUND Podocyturia is a marker of diabetic nephr- opathy, a possible determinant of its progression and a powerful risk factor for cardiovascular disease. A reduction in podocyte adhesion to the glomerular basement membrane (GBM) via downregulation of alpha3beta1 integrin expression, the main podocyte anchoring dimer to the GBM, may represent one of the mechanisms of podocyturia in glomerular disease. This study investigated the role of mechanical forces and transforming growth factor beta1 (TGFbeta1) in podocyte adhesion and integrin expression. METHODS Conditionally immortalized murine podocytes were exposed to mechanical stretch and/or TGFbeta1 for 48 h. Podocyte adhesion, apoptosis and alpha3beta1 integrin expression were assessed. RESULTS Stretch and TGFbeta1 significantly reduced podocyte adhesion and alpha3beta1 integrin expression, events paralleled by increased apoptosis. Blockade of beta1 integrin, with a specific antibody, demonstrated a reduced podocyte adhesion indicating that beta1 integrin downregulation was required for the loss of podocyte adhesion. This was linked to an increase in podocyte apoptosis. The role of apoptosis in podocyte adhesion was further investigated using caspase-3 inhibitors. Podocyte apoptosis inhibition did not affect stretch- and TGFbeta1-mediated integrin downregulation and the loss of podocyte adhesion, suggesting that alpha3beta1 integrin downregulation is sufficient to alter cell adhesion. Although stretch significantly increased podocyte TGFbeta type I, II and III receptors but not podocyte TGFbeta1 secretion, the combination of stretch and TGFbeta1 did not show any additive or synergistic effects on podocyte adhesion and alpha3beta1 integrin expression. CONCLUSIONS These results suggest that downregulation of alpha3beta1 integrin expression, by mechanical forces or TGFbeta1, is per se sufficient to reduce podocyte adhesion. Apoptosis may represent a parallel important determinant of the podocyte loss from the GBM.

Cardiovascular and noncardiovascular comorbidities in patients with chronic heart failure

A broad spectrum of concomitant disorders may complicate heart failure adding further morbidity and mortality risk. Comorbidities may be subdivided into cardiovascular and noncardiovascular. The first group includes hypertension, coronary artery disease, peripheral artery disease, cerebrovascular disease, arrhythmias and valvular heart disease. Noncardiovascular comorbidities include respiratory, endocrine, metabolic, nutritional, renal, hematopoietic, neurological as well as musculoskeletal conditions. In recent years, advances in the treatment of heart failure have not been attended by important changes in management of its comorbidities. They now seem to be major causes of the poor prognosis of heart failure patients. In this review we provide an updated summary of the epidemiological, pathophysiological and clinical characteristics of comorbidities as well as their potential impact for heart failure treatment.

Pioglitazone improves in vitro viability and function of endothelial progenitor cells from individuals with impaired glucose tolerance.

Background Evidence suggests that the PPARγ-agonist insulin sensitizer pioglitazone, may provide potential beneficial cardiovascular (CV) effects beyond its anti-hyperglycaemic function. A reduced endothelial progenitor cell (EPC) number is associated with impaired glucose tolerance (IGT) or diabetes, conditions characterised by increased CV risk. Aim To evaluate whether pioglitazone can provide benefit in vitro in EPCs obtained from IGT subjects. Materials and Methods Early and late-outgrowth EPCs were obtained from peripheral blood mononuclear cells of 14 IGT subjects. The in vitro effect of pioglitazone (10 µM) with/without PPARγ-antagonist GW9662 (1 µM) was assessed on EPC viability, apoptosis, ability to form tubular-like structures and pro-inflammatory molecule expression. Results Pioglitazone increased early and late-outgrowth EPC viability, with negligible effects on apoptosis. The capacity of EPCs to form tubular-like structures was improved by pioglitazone in early (mean increase 28%; p = 0.005) and late-outgrowth (mean increase 30%; p = 0.037) EPCs. Pioglitazone reduced ICAM-1 and VCAM-1 adhesion molecule expression in both early (p = 0.001 and p = 0.012 respectively) and late-outgrowth (p = 0.047 and p = 0.048, respectively) EPCs. Similarly, pioglitazone reduced TNFα gene and protein expression in both early (p = 0.034;p = 0.022) and late-outgrowth (p = 0.026;p = 0.017) EPCs compared to control. These effects were prevented by incubation with the PPARγ-antagonist GW9662. Conclusion Pioglitazone exerts beneficial effects in vitro on EPCs isolated from IGT subjects, supporting the potential implication of pioglitazone as a CV protective agents.

Effects of oral administration of orodispersible levo-carnosine on quality of life and exercise performance in patients with chronic heart failure

OBJECTIVE Chronic heart failure (CHF) is characterized by several micronutrient deficits. Amino acid supplementation may have a positive effect on nutritional and metabolic status in patients with CHF. Levo-carnosine (β-alanyl-L-histidine) is expressed at a high concentration in myocardium and muscle. Preliminary studies with L-carnosine in healthy individuals have suggested a potential role in improving exercise performance. To our knowledge, no study has been conducted in patients with heart failure. The aim of this study was to test the oral supplementation of L-carnosine and its effects on quality of life and exercise performance in patients with stable CHF. METHODS Fifty patients with stable CHF and severe left-ventricular systolic dysfunction on optimal medical therapy were randomized 1:1 to receive oral orodispersible L-carnosine (500 mg OD) or standard treatment. Left-ventricular ejection fraction (LVEF) was measured by echocardiography. Cardiopulmonary stress test, 6-minute walking test (6 MWT) and quality-of-life (visual analog scale score and the EuroQOL five dimensions questionnaire [EQ-5D]) were performed at baseline and after 6 mo. RESULTS Patients receiving orodispersible L-carnosine had an improvement in 6 MWT distance (P = 0.014) and in quality-of-life (VAS score) (P = 0.039) between baseline and follow-up. Compared with controls, diet supplementation with orodispersible L-carnosine was associated with an improvement in peakVO2 (P < 0.0001), VO2 at anaerobic threshold, peak exercise workload, 6 MWT and quality-of-life assessed by the EQ-5D test and the VAS score. CONCLUSION This study suggests that L-carnosine, added to conventional therapy, has beneficial effects on exercise performance and quality of life in stable CHF. More data are necessary to evaluate its effects on left-ventricular ejection fraction and prognosis in CHF.

Concomitant Diabetes Mellitus and Heart Failure

The prevalence of patients with concomitant diabetes mellitus (DM) and heart failure (HF) is growing exponentially. Patients with HF and DM show specific metabolic, neurohormonal, and structural heart abnormalities, which potentially contribute to worse HF outcomes than seen in patients without comorbid DM. Subgroup analysis of recent trials suggest that patients with HF and DM may respond differently to standard therapy, and data are emerging on the possible increase in the risk of hospitalizations for HF in patients with DM treated with specific class of antidiabetic agents, pointing to the need of developing specific medications to be tested in dedicated future studies to address the unique metabolic and hemodynamic alterations seen in these patients.