Opposite effects of ß2-adrenoceptor gene deletion on insulin signaling in liver and skeletal muscle.

BACKGROUND AND AIM: ß2-Adrenoceptors (ß2-ARs) are G protein-coupled receptors (GPCRs) expressed in the major insulin target tissues. The interplay between ß2-AR and insulin pathways is involved in the maintenance of glucose homeostasis. The aim of this study was to explore the consequences of ß2-ARs deletion on insulin sensitivity and insulin signaling cascade in metabolically active tissues. METHODS AND RESULTS: We evaluated glucose homeostasis in skeletal muscle and liver of ß2-AR-null mice (ß2-AR-/-) by performing in vivo (glucose tolerance test and insulin tolerance test) and ex vivo (glucose uptake and glycogen determination) experiments. ß2-AR gene deletion is associated with hepatic insulin resistance and preserved skeletal muscle insulin sensitivity. Importantly, we demonstrate that hepatic ß2-AR regulates insulin-induced AKT activation via Grb2-mediated SRC recruitment through a Gi-independent mechanism. CONCLUSIONS: ß-AR stimulation contributes to the development of early stages of insulin resistance progression in the liver. Our findings indicate that the cross-talk between ß2-AR and insulin signaling represents a fundamental target towards the development of novel therapeutic approaches to treat type 2 diabetes and metabolic syndrome.

The possible role of chromosome X variability in hypertensive familiarity.

Familiarity participates in the pathogenesis of hypertension, although only recently, whole genome studies have proposed regions of the human genome possibly involved in the transmission of the hypertensive phenotype. Although studies have mainly focused on autosome, hitherto the influence of sex on familial transmission of hypertension has not been considered. We analysed the database of the Campania Salute Network of Hypertension center of the Federico II University Hospital of Naples (Italy), using dichotomous variables for paternal and maternal familiarity and gender (male and female) of 12 504 hypertensive patients (6868 males and 5636 females) and 6352 controls (3484 males and 2868 females), totaling 18 856 subjects. In the hypertensive group, familiarity was present in 75% of cases with odds of 3.77 and in only 26% of the normotensives with odds of 0.94. The odds ratio (OR) indicated that familiarity increases the risk of developing hypertension by 2.91 (95% confidence interval (CI)=2.67-3.17, P<0.001) times. Additionally, maternal familiarity was 37% (OR=3.01, 95% CI=2.66-3.41, P<0.001), paternal familiarity was 21% (OR=2.31, 95% CI=2.01-2.68, P<0.001) and the double familiarity was 17% (OR=3.45, 95% CI=2.87-4.01, P<0.001), thus suggesting a plausible association between maternal familiarity and development of hypertension; this finding was observed both in male and in female patients, although the phenomenon was larger in males. Given the dominance of maternal transmission in males, by genome-wide analysis of the X chromosome, we found two regions that were differently distributed in male hypertensives with maternal hypertension. Our data highlight the importance of genetic variants in the X chromosome to the maternal transmission of the hypertensive phenotype.

Telemonitoring in heart failure patients treated by cardiac resynchronisation therapy with defibrillator (CRT-D): the TELECART Study.

AIM: Telemonitoring (TM) is a safe and efficient monitoring system for internal cardioverter defibrillator device (ICD) recipients. TM has been used to track info on the clinical status of heart failure patients treated by ICD and/or cardiac resynchronisation therapy defibrillator (CRT-D). The aim of this study was to investigate the impact of TM on clinical outcomes in a population of CRT-D patients with heart failure. METHODS: In a multicentre, randomised study, patients with chronic heart failure, New York Heart Association (NYHA) functional class II or III, left bundle branch block, severe left ventricle ejection fraction reduction (LVEF < 35%) have been identified and screened. RESULTS: One hundred and ninety-one patients have been randomised to receive either a CRT-D with TM or a CRT-D with traditional ambulatory monitoring (control group) and completed the 12-month study follow-up. Primary endpoints were all cause death, cardiac death and hospital admission for heart failure. Secondary endpoints were atrial fibrillation, sustained episodes, non-sustained and self terminated ventricular tachyarrhythmia, sustained ventricular tachycardia, and ventricular fibrillation, ICD shocks and percentage of CRT-D responder patients. Univariate analysis identified the following factors predicting hospitalisation: TM, age, chronic kidney disease, hypercholesterolaemia, LVEF and NYHA class. At multivariate analysis, TM was the only factor predicting heart failure hospitalisation (hazard ratio 0.6, 0.42-0.79, 95% CI, p = 0.002), without affecting overall mortality and cardiac deaths events. CONCLUSIONS: Taken together, our data indicate the importance of TM in predicting heart failure hospitalisation in patients treated with CRT-D.

Application of microRNAs in diagnosis and treatment of cardiovascular disease.

Cardiovascular disease (CVD) is a major cause of morbidity and mortality worldwide. Innovative, more stringent diagnostic and prognostic biomarkers and effective treatment options are needed to lessen its burden. In recent years, microRNAs have emerged as master regulators of gene expression - they bind to complementary sequences within the mRNAs of their target genes and inhibit their expression by either mRNA degradation or translational repression. microRNAs have been implicated in all major cellular processes, including cell cycle, differentiation and metabolism. Their unique mode of action, fine-tuning gene expression rather than turning genes on/off, and their ability to simultaneously regulate multiple elements of relevant pathways makes them enticing potential biomarkers and therapeutic targets. Indeed, cardiovascular patients have specific patterns of circulating microRNA levels, often early in the disease process. This article provides a systematic overview of the role of microRNAs in the pathophysiology, diagnosis and treatment of CVD.

Cardiac resynchronisation therapy response predicts occurrence of atrial fibrillation in non-ischaemic dilated cardiomyopathy.

AIM: The aim of this study was to determine whether or not cardiac resynchronization therapy (CRT) has a favourable effect on the incidence of new-onset atrial fibrillation (AF) in a homogeneous population of patients with non-ischaemic idiopathic-dilated cardiomyopathy and severe heart failure. METHODS: We designed a single-centre prospective study and enrolled 58 patients AF naïve when received CRT. After 1 year of follow-up our population was subdivided into responders (72.4%) and non-responders (27.6%), so as to compare the incidence of AF after 1, 2 and 3 years of follow-up in these two groups. RESULTS: Already after 1 year, there was a significant (p < 0.05) difference in new-onset AF in non-responder patients with respect to responders (18.2% vs. 3.3%). These data were confirmed at 2 years (33.3% vs. 12.2%) and 3 years (50.0% vs. 15.0%) follow-up. In particular, 3 years after device implantation non-responders had an increased risk to develop new-onset AF (OR = 5.67). CONCLUSIONS: This is the first study analysing long-term effects of CRT in a homogeneous population of patients with non-ischaemic dilated cardiomyopathy, indicating the favourable role of this non-pharmacological therapy on the prevention of AF.

Overproduction of phosphoprotein enriched in diabetes (PED) induces mesangial expansion and upregulates protein kinase C-beta activity and TGF-beta1 expression.

AIMS/HYPOTHESIS: Overproduction of phosphoprotein enriched in diabetes (PED, also known as phosphoprotein enriched in astrocytes-15 [PEA-15]) is a common feature of type 2 diabetes and impairs insulin action in cultured cells and in mice. Nevertheless, the potential role of PED in diabetic complications is still unknown. METHODS: We studied the effect of PED overproduction and depletion on kidney function in animal and cellular models. RESULTS: Transgenic mice overexpressing PED (PEDTg) featured age-dependent increases of plasma creatinine levels and urinary volume, accompanied by expansion of the mesangial area, compared with wild-type littermates. Serum and kidney levels of TGF-beta1 were also higher in 6- and 9-month-old PEDTg. Overexpression of PED in human kidney 2 cells significantly increased TGF-beta1 levels, SMAD family members (SMAD)2/3 phosphorylation and fibronectin production. Opposite results were obtained following genetic silencing of PED in human kidney 2 cells by antisense oligonucleotides. Inhibition of phospholipase D and protein kinase C-beta by 2-butanol and LY373196 respectively reduced TGF-beta1, SMAD2/3 phosphorylation and fibronectin production. Moreover, inhibition of TGF-beta1 receptor activity and SMAD2/3 production by SB431542 and antisense oligonucleotides respectively reduced fibronectin secretion by about 50%. TGF-beta1 circulating levels were significantly reduced in Ped knockout mice and positively correlated with PED content in peripheral blood leucocytes of type 2 diabetic patients. CONCLUSIONS/INTERPRETATION: These data indicate that PED regulates fibronectin production via phospholipase D/protein kinase C-beta and TGF-beta1/SMAD pathways in kidney cells. Raised PED levels may therefore contribute to the abnormal accumulation of extracellular matrix and renal dysfunction in diabetes.

Endothelial alpha1-adrenoceptors regulate neo-angiogenesis.

BACKGROUND AND PURPOSE: Intact endothelium plays a pivotal role in post-ischaemic angiogenesis. It is a phenomenon finely tuned by activation and inhibition of several endothelial receptors. The presence of alpha(1)-adrenoceptors on the endothelium suggests that these receptors may participate in regenerative phenomena by regulating the responses of endothelial cells involved in neo-angiogenesis. EXPERIMENTAL APPROACH: We evaluated the expression of the subtypes of the alpha(1)-adrenoceptor in isolated endothelial cells harvested from Wistar-Kyoto (WKY) rats. We explored the possibility these alpha(1)-adrenoceptors may influence the pro-angiogenic phenotype of endothelial cells in vitro. In vivo, we used a model of hindlimb ischaemia in WKY rats, to assess the effects of alpha(1) adrenoceptor agonist or antagonist on angiogenesis in the ischaemic hindlimb by laser Doppler blood flow measurements, digital angiographies, hindlimb perfusion with dyed beads and histological evaluation. KEY RESULTS: In vitro, pharmacological antagonism of alpha(1)-adrenoceptors in endothelial cells from WKY rats by doxazosin enhanced, while stimulation of these adrenoceptors with phenylephrine, inhibited endothelial cell proliferation and DNA synthesis, ERK and retinoblastoma protein (Rb) phosphorylation, cell migration and tubule formation. In vivo, we found increased alpha(1)-adrenoceptor density in the ischaemic hindlimb, compared to non-ischaemic hindlimb, suggesting an enhanced alpha(1)-adrenoceptor tone in the ischaemic tissue. Treatment with doxazosin (0.06 mg kg(-1) day(-1) for 14 days) did not alter systemic blood pressure but enhanced neo-angiogenesis in the ischaemic hindlimb, as measured by all our assays. CONCLUSIONS: Our findings support the hypothesis that the alpha(1)-adrenoceptors in endothelial cells provide a negative regulation of angiogenesis.