Neutrophil microvesicles drive atherosclerosis by delivering miR-155 to atheroprone endothelium.

Neutrophils are implicated in the pathogenesis of atherosclerosis but are seldom detected in atherosclerotic plaques. We investigated whether neutrophil-derived microvesicles may influence arterial pathophysiology. Here we report that levels of circulating neutrophil microvesicles are enhanced by exposure to a high fat diet, a known risk factor for atherosclerosis. Neutrophil microvesicles accumulate at disease-prone regions of arteries exposed to disturbed flow patterns, and promote vascular inflammation and atherosclerosis in a murine model. Using cultured endothelial cells exposed to disturbed flow, we demonstrate that neutrophil microvesicles promote inflammatory gene expression by delivering miR-155, enhancing NF-κB activation. Similarly, neutrophil microvesicles increase miR-155 and enhance NF-κB at disease-prone sites of disturbed flow in vivo. Enhancement of atherosclerotic plaque formation and increase in macrophage content by neutrophil microvesicles is dependent on miR-155. We conclude that neutrophils contribute to vascular inflammation and atherogenesis through delivery of microvesicles carrying miR-155 to disease-prone regions.

Combined Angiotensin Receptor Modulation in the Management of Cardio-Metabolic Disorders.

Cardiovascular and metabolic disorders, such as hypertension, insulin resistance, dyslipidemia or obesity are linked with chronic low-grade inflammation and dysregulation of the renin-angiotensin system (RAS). Consequently, RAS inhibition by ACE inhibitors or angiotensin AT1 receptor (AT1R) blockers is the evidence-based standard for cardiovascular risk reduction in high-risk patients, including diabetics with albuminuria. In addition, RAS inhibition reduces the new onset of diabetes mellitus. Yet, the high and increasing prevalence of metabolic disorders, and the high residual risk even in properly treated patients, calls for additional means of pharmacological intervention. In the past decade, the stimulation of the angiotensin AT2 receptor (AT2R) has been shown to reduce inflammation, improve cardiac and vascular remodeling, enhance insulin sensitivity and increase adiponectin production. Therefore, a concept of dual AT1R/AT2R modulation emerges as a putative means for risk reduction in cardio-metabolic diseases. The approach employing simultaneous RAS blockade (AT1R) and RAS stimulation (AT2R) is distinct from previous attempts of double intervention in the RAS by dual blockade. Dual blockade abolishes the AT1R-linked RAS almost completely with subsequent risk of hypotension and hypotension-related events, i.e. syncope or renal dysfunction. Such complications might be especially prominent in patients with renal impairment or patients with isolated systolic hypertension and normal-to-low diastolic blood pressure values. In contrast to dual RAS blockade, the add-on of AT2R stimulation does not exert significant blood pressure effects, but it may complement and enhance the anti-inflammatory and antifibrotic/de-stiffening effects of the AT1R blockade and improve the metabolic profile. Further studies will have to investigate these putative effects in particular for settings in which blood pressure reduction is not primarily desired.

Expression and functional role of the prorenin receptor in the human adrenocortical zona glomerulosa and in primary aldosteronism.

OBJECTIVES: Prorenin can be detected in plasma of hypertensive patients. If detected in patients with primary aldosteronism could implicate prorenin in the development of primary aldosteronism. To address this issue, we measured the plasma prorenin levels in primary aldosteronism patients, the expression of the prorenin receptor (PRR) in the normal human adrenocortical zona glomerulosa and aldosterone-producing adenoma (APA), and we investigated the functional effects of PRR activation in human adrenocortical cells. METHOD: Plasma renin activity, aldosterone, and active and total trypsin-activated renin were measured in primary aldosteronism patients, essential hypertensive patients, and healthy individuals, and then prorenin levels were calculated. Localization and functional role of PRR were investigated in human and rat tissues, and aldosterone-producing cells. RESULTS: Primary aldosteronism patients had detectable plasma levels of prorenin. Using digital-droplet real-time PCR, we found a high PRR-to-porphobilinogen deaminase ratio in both the normal adrenal cortex and APAs. Marked expression of the PRR gene and protein was also found in HAC15 cells. Immunoblotting, confocal, and immunogold electron microscopy demonstrated PRR at the cell membrane and intracellularly. Renin and prorenin significantly triggered both CYP11B2 expression (aldosterone synthase) and ERK1/2 phosphorylation, but only CYP11B2 transcription was prevented by aliskiren. CONCLUSION: The presence of detectable plasma prorenin in primary aldosteronism patients, and the high expression of PRR in the normal human adrenal cortex, APA tissue, CD56+ aldosterone-producing cells, along with activation of CYP11B2 synthesis and ERK1/2 phosphorylation, suggest that the circulating and locally produced prorenin may contribute to the development or maintenance of human primary aldosteronism.

AT(2) receptor and tissue injury: therapeutic implications.

The renin-angiotensin system (RAS) plays an important role in the initiation and progression of tissue injuries in the cardiovascular and nervous systems. The detrimental actions of the AT1 receptor (AT1R) in hypertension and vascular injury, myocardial infarction and brain ischemia are well established. In the past twenty years, protective actions of the RAS, not only in the cardiovascular, but also in the nervous system, have been demonstrated. The so-called protective arm of the RAS includes AT2-receptors and Mas receptors (AT2R and MasR) and is characterized by effects different from and often opposing those of the AT1R. These include anti-inflammation, anti-fibrosis, anti-apoptosis and neuroregeneration that can counterbalance pathological processes and enable recovery from disease. The recent development of novel, small-molecule AT2R agonists offers a therapeutic potential in humans with a variety of clinical indications.

Prevention of coronary artery disease: recent advances in the management of hypertension.

As coronary artery disease (CAD) still represents the leading cause of death worldwide, more efforts should be made to improve CAD prevention with both lifestyle changes and medical treatment. Elevated blood pressure has been identified as a risk factor for CAD; however, recent evidence suggests that lowering blood pressure too much could be harmful in patients at high cardiovascular risk. Despite the availability of a wide selection of antihypertensive drugs, new strategies and treatments are needed to improve blood pressure control and reduce cardiovascular risk factors associated with elevated blood pressure. New fixed-dose combinations have been recently approved; they usually contain an inhibitor of the renin-angiotensin system, a calcium antagonist and/or a diuretic. Although research and development related to new antihypertensive drugs has slowed in recent years, some new antihypertensive compounds with novel mechanisms of action or dual activity are currently in clinical development.

Peritoneal macrophage priming in cirrhosis is related to ERK phosphorylation and IL-6 secretion.

BACKGROUND: Bacterial infections are common complications arising in patients with cirrhosis and ascites. Translocation of bacterial DNA is a dynamic process that is associated with an increased inflammatory response and a poor prognosis in this setting. The aim of this study was to study whether peritoneal macrophages remain in a chronic primed status to allow a rapid response to subsequent events of bacterial translocation. PATIENTS AND METHODS: Peritoneal monocyte-derived macrophages were isolated from 25 patients with cirrhosis and non-infected ascites and compared with donor's blood monocytes. Activation cell-surface markers were screened using flow-cytometry, and the phosphorylation state of ERK 1/2, p38 MAP Kinase, PKB/Akt and transcription factors c-Jun and p65 NFκB were evaluated using Western blot. Synthesis of tumour necrosis factor alpha, interleukin 6 (IL-6) and interleukin-10 (IL-10) at baseline and in response to bacterial stimuli was evaluated using ELISA. RESULTS: A high expression of CD54, CD86 and HLA-DR at baseline was displayed by peritoneal macrophages. Increased phosphorylated levels of ERK1/2, protein kinase B (PKB) and c-Jun, together with IL-6 production, were observed in peritoneal macrophages at baseline compared with donors' blood monocytes. A positive correlation was established between basal IL-6 levels and extracellular signal-regulated kinase (ERK) phosphorylation in peritoneal macrophages from patients with cirrhosis (r=0·9; P=0·005). Addition of lipopolysaccharide induced higher phosphorylation levels of all studied signalling intermediates than synthetic-oligodeoxydinucleotides, but similar end-stage p65 NFκB. CONCLUSIONS: A sustained immune response is present in ascitic fluid of cirrhotic patients, even in the temporal absence of bacterial antigens. This would facilitate a fast response, probably controlled by IL-6, against repeated bacterial-DNA translocation or in liver chronic inflammation.

Isolation of human adrenocortical aldosterone-producing cells by a novel immunomagnetic beads method.

We detected intense CD56 immunostaining in the zona glomerulosa (ZG) and medulla of the normal human adrenal gland and therefore identified CD56, the neural cell adhesion molecule, as a membrane antigen specific for the ZG, aldosterone-producing adenoma (APA), and chromaffin cells. The APA and pheochromocytoma cells, which are histogenetically derived from the ZG and medulla, respectively, also showed intense CD56 immunostaining. Based on these findings we developed a strategy for isolating cells from the ZG and APA using CD56 immunobinding to magnetic beads. Morphology, gene expression studies, and aldosterone measurement confirmed that CD56 positive (+) cells were ZG and APA cells. Analysis of CD56+ cells under light and phase contrast microscopy evidenced that these cells formed clumps, as the ZG cells usually do; with electron microscopy they showed multiple features typical of a steroidogenic phenotype. Expression levels of the CD56 and the aldosterone synthase (CYP11B2) gene were markedly higher in CD56+ cells than CD56- cells (+1600 and +2100% increase, respectively). Moreover, aldosterone secretion was higher (+1380%) from CD56+ cells than from CD56- cells. Hence, this novel methodology allows isolation of a pure population of ZG and APA cells exhibiting multiple characteristics of the aldosterone-producing cells.