Abstract-Accumulating evidence indicates a key role of inflammation in hypertension and cardiovascular disorders. However, the role of inflammatory processes in neurogenic hypertension remains to be determined. Thus, our objective in the present study was to test the hypothesis that activation of microglial cells and the generation of proinflammatory cytokines in the paraventricular nucleus (PVN) contribute to neurogenic hypertension. Intracerebroventricular infusion of minocycline, an anti-inflammatory antibiotic, caused a significant attenuation of mean arterial pressure, cardiac hypertrophy, and plasma norepinephrine induced by chronic angiotensin II infusion. This was associated with decreases in the numbers of activated microglia and mRNAs for interleukin (IL) 1␤, IL-6, and tumor necrosis factor-␣, and an increase in the mRNA for IL-10 in the PVN. Overexpression of IL-10 induced by recombinant adenoassociated virus-mediated gene transfer in the PVN mimicked the antihypertensive effects of minocycline. Furthermore, acute application of a proinflammatory cytokine, IL-1␤, into the left ventricle or the PVN in normal rats resulted in a significant increase in mean arterial pressure. Collectively, this indicates that angiotensin II induced hypertension involves activation of microglia and increases in proinflammatory cytokines in the PVN. These data have significant implications on the development of innovative therapeutic strategies for the control of neurogenic hypertension. (Hypertension. 2010;56:297-303.)Key Words: angiotensin II Ⅲ hypertension Ⅲ minocycline Ⅲ interleukin 10 Ⅲ microglia Ⅲ paraventricular nucleus Ⅲ cytokine I nflammation has been implicated in hypertension and cardiovascular diseases in both animal models and human diseases. 1,2 Increases in levels of plasma proinflammatory cytokines (PICs) and other markers of inflammation are associated with the progression of hypertension, whereas immune suppression produces beneficial outcomes. 3,4 Despite evidence for the participation of peripheral cytokines and inflammation in cardiovascular disease, little is known about their involvement in neurogenic hypertension. Studies from Francis and collaborators 5,6 have indicated that angiotensin (Ang) II-induced hypertension involves activation of tumor necrosis factor-␣ (TNF-␣) and nuclear factor B and production of reactive oxygen species in the brain. These observations have led us to propose that Ang II-induced neurogenic hypertension involves activation of microglial cells and production of PICs within the brain. Our objective in the present study was to test this hypothesis.We focused on the paraventricular nucleus (PVN) and a chronic Ang II infusion rat model of hypertension for this study, based on the following rationales. First, the PVN integrates signals/inputs from circumventricular organs and other cardiovascular-relevant brain areas and transmits them to the rostroventrolateral medulla and other downstream areas to influence sympathetic nerve activity. 7 Second, chronic Ang II infusion is an e...

Our observations demonstrate a cardiopulmonary protective role for the ACE2/Ang-(1-7)/Mas axis in the treatment of lung disorders.

Rationale : Studies have demonstrated that angiotensin-converting enzyme 2 (ACE2) plays a protective role against lung diseases, including pulmonary hypertension (PH). Recently, an antitrypanosomal drug, diminazene aceturate (DIZE), was shown to exert an "offtarget" effect of enhancing the enzymatic activity of ACE2 in vitro. Objectives: To evaluate the pharmacological actions of DIZE in experimental models of PH. Methods: PH was induced in male Sprague Dawley rats by monocrotaline, hypoxia, or bleomycin challenge. Subsets of animals were simultaneously treated with DIZE. In a separate set of experiments, DIZE was administered after 3 weeks of PH induction to determine whether the drug could reverse PH. Measurements and Main Results: DIZE treatment significantly prevented the development of PH in all of the animal models studied. The protective effects were associated with an increase in the vasoprotective axis of the lung renin-angiotensin system, decreased inflammatory cytokines, improved pulmonary vasoreactivity, and enhanced cardiac function. These beneficial effects were abolished by C-16, an ACE2 inhibitor. Initiation of DIZE treatment after the induction of PH arrested disease progression. Endothelial dysfunction represents a hallmark of PH pathophysiology, and growing evidence suggests that bone marrow-derived angiogenic progenitor cells contribute to endothelial homeostasis. We observed that angiogenic progenitor cells derived from the bone marrow of monocrotaline-challenged rats were dysfunctional and were repaired by DIZE treatment. Likewise, angiogenic progenitor cells isolated from patients with PH exhibited diminished migratory capacity toward the key chemoattractant stromal-derived factor 1a, which was corrected by in vitro DIZE treatment. Conclusions: Our results identify a therapeutic potential of DIZE in PH therapy.Keywords: pulmonary hypertension; ACE2; angiogenic progenitor cells; diminazene Pulmonary hypertension (PH) is a life-threatening disease characterized by elevated pressure in the pulmonary arteries and What This Study Adds to the FieldWe show that diminazene, an antitrypanosomal drug, attenuates hemodynamic changes, prevents maladaptive right ventricular remodeling, and enhances pulmonary vasorelaxation in experimental models of PH through activation of ACE2. Furthermore, diminazene improves the functions of APCs obtained from experimental animals and patients with PH. This study identifies a new application for an existing drug, which could be successfully developed for PH therapeutics.

Autonomic nervous system (ANS) dysfunction, exaggerated inflammation and impaired vascular repair are all hallmarks of hypertension. Considering the bone marrow (BM) is a major source of the inflammatory cells (ICs) and endothelial progenitor cells (EPCs), we hypothesized that impaired BM-ANS interaction contributes to dysfunctional BM activity in hypertension. In the SHR, we observed a >30% increase in BM and blood ICs (CD4.8+), and a >50% decrease in EPCs (CD90+.CD4.5.8-) compared to the normotensive Wistar-Kyoto (WKY) rat. Increased tyrosine hydroxylase (70%) and norepinephrine (NE, 160%), and decreased choline acetyl transferase (30%) and acetylcholine esterase (55%) indicated imbalanced ANS in SHR BM. In WKY, night time-associated elevation in SNA (50%) and BM NE (41%) was associated with increased ICs (50%) and decreased EPCs (350%), while BM sympathetic denervation decreased ICs (25%) and increased EPCs (40%). In contrast, these effects were blunted in SHR, possibly due to chronic downregulation of BM adrenergic receptor α2a (by 50-80%) and β2 (30-45%). Application of NE resulted in increased BM IC activation/release, which was prevented by pre-administration of Ach. Electrophysiological recordings of femoral SNA (fSNA) showed a more robust fSNA activity in SHR compared to WKY, peaking earlier in the respiratory cycle, indicative of increased sympathetic tone. Finally, manganese-enhanced magnetic resonance imaging (MEMRI) demonstrated that pre-sympathetic neuronal activation in SHR was associated with an accelerated retrograde transport of the GFP-labeled pseudorabies virus from the BM. These observations demonstrate that a dysfunctional BM ANS is associated with imbalanced EPCs and ICs in hypertension.

Hyperactivity of the axis ACE/AngII/AT1R of the renin‐angiotensin system is associated with occurrence of acute thrombotic event. Recently a novel concept of a counterrugulatory axis, ACE2/Ang‐(1‐7)/Mas, has emerged. We hypothesized that ACE2 would be protective against thrombosis. Thrombus was induced in the vena cava of SHR and WKY rats by FeCl3 solution. ACE2 and ACE protein expression and activities in the thrombus were determined by Western blot and fluorogenic kinetic assays, respectively. Real time thrombus formation was visualized by intravital microscopy of the vessels of nude mice. Ferric chloride‐induced thrombus weight was 40% higher in the SHR compared to WKY rats. This was associated with a 20% decreased in ACE2 activity in the thrombus of the SHR. In contrast, ACE2 protein expression and ACE activity did not differ between the thrombus of WKY rats and SHR. Inhibition of ACE2 by DX600 increased the thrombus weight by 30%, preferentially in the SHR. Furthermore, treatment with XNT resulted in a 30% attenuation of thrombus formation in both the SHR and WKY. In addition, XNT treatment prolonged the time for complete vessel occlusion and reduced thrombus size when observed under real‐time intravital microscopy. Our data demonstrated that a decrease in ACE2 activity is associated with increased thrombus formation in the SHR. Furthermore, activation of ACE2 attenuates thrombus formation.

Oxidative stress in the brain is implicated in increased sympathetic drive, inflammatory status and vascular dysfunctions, associated with development and establishment of hypertension. However, little is known about the mechanism of this impaired brain-vascular communication. Here, we tested the hypothesis that increased oxidative stress in the brain cardioregulatory areas, such as the paraventricular nucleus (PVN) of the hypothalamus, is driven by mitochondrial reactive oxygen species (ROS) and leads to increased inflammatory cells (ICs) and decreased/dysfunctional endothelial progenitor cells (EPCs), thereby compromising vasculature repair and accelerating hypertension. Chronic angiotensin II (Ang II) infusion resulted in elevated blood pressure and sympathetic vasomotor drive, decreased spontaneous baroreflex gain, and increased microglia activation in the PVN. This was associated with 46% decrease in BM EPCs and 250% increase in BM ICs, resulting in 5 fold decrease of EPCs/ICs ratio in the BM. Treatment with mitoTEMPO, a scavenger of mitochondrial O2−• intracerebroventricularly but not subcutaneously, attenuated Ang II-induced hypertension, decreased activation of microglia in the PVN, and normalized EPCs/ICs. This functional communication between the brain and BM was confirmed by retrograde neuronal labeling from the BM with GFP-tagged pseudorabies virus (PRV). Administration of GFP-PRV into the BM resulted in predominant labeling of PVN neurons within 3 days, with some fluorescence in the NTS, RVLM and SFO. Taken together, these data demonstrate that inhibition of mitochondrial ROS attenuates Ang II-induced hypertension and corrects the imbalance in EPCs/ICs in the BM. They suggest that an imbalance in vascular reparative and ICs may perpetuate vascular pathophysiology in this model of hypertension.

We previously reported children homozygous for two MC3R sequence variants (C17A+G241A) have greater fat mass than controls. Here we show, using homozygous knock-in mouse models in which we replace murine Mc3r with wild-type human (MC3RhWT/hWT) and double-mutant (C17A+G241A) human (MC3RhDM/hDM) MC3R, that MC3RhDM/hDM have greater weight and fat mass, increased energy intake and feeding efficiency, but reduced length and fat-free mass compared with MC3RhWT/hWT. MC3RhDM/hDM mice do not have increased adipose tissue inflammatory cell infiltration or greater expression of inflammatory markers despite their greater fat mass. Serum adiponectin levels are increased in MC3RhDM/hDM mice and MC3RhDM/hDM human subjects. MC3RhDM/hDM bone- and adipose tissue-derived mesenchymal stem cells (MSCs) differentiate into adipocytes that accumulate more triglyceride than MC3RhWT/hWT MSCs. MC3RhDM/hDM impacts nutrient partitioning to generate increased adipose tissue that appears metabolically healthy. These data confirm the importance of MC3R signalling in human metabolism and suggest a previously-unrecognized role for the MC3R in adipose tissue development.

622( P ro)renin receptor (PRR) is highly expressed in many tissues, including those of the heart and brain, 1,2 and plays an important role in the maintenance of cardiovascular homeostasis in the periphery. 3,4 However, the role of PRR in the brain remains poorly understood. Despite intrinsically low renin concentrations in the brain, the ability of renin to signal in a similar manner to angiotensin (Ang)-II, 5 coupled with the presence of PRR in the brain cardioregulatory areas, 2,6 suggests a role for PRR in central cardiovascular control. Our previous study revealed that PRR expression is significantly increased in the nucleus of the solitary tract (NTS) and the supraoptic nucleus (SON) of spontaneously hypertensive rats (SHR) compared with normotensive Wistar Kyoto (WKY) controls. 6 Genetic knockdown of PRR in the SHR SON 6 and other cardioregulatory regions, such as the subfornical organ (SFO) 7 in hypertensive rats, resulted in a reduction of blood pressure (BP). However, the role of NTS PRR in BP control and its precise mechanisms remain elusive.Our interest in the role of NTS PRR derives from the following: (1) The NTS is the central termination site of baroreceptor input, regulating both the set-point of arterial pressure and the gain of the baroreflex, mechanisms essential for short-and long-term homeostatic control of arterial pressure 8,9 ; (2) In the hypertensive model, the NTS exhibits an abnormal inflammatory state because the expression of many inflammatory mediators known to be involved in modulating synaptic transmission, including interleukin (IL)-6 and C-C motif ligand 5 (Ccl5), are downregulated in the SHR NTS compared with the WKY rats 10,11 ; and (3) PRR mRNA in the SHR NTS is significantly increased compared with the WKY rats. 6 We propose that altered activity of PRR in the NTS is linked to hypertension, and that the NTS PRR regulates BP Abstract-The importance of the (pro)renin receptor (PRR) in the function of the central nervous system is increasingly evident because PRR seems to play a role in neuronal control of cardiovascular function. PRR expression is elevated in the nucleus of the solitary tract (NTS) of spontaneously hypertensive rats (SHR).In this study, we tested the hypothesis that altered activity of PRR in the NTS is linked to hypertension. Eight weeks of chronic knockdown of the NTS PRR, using recombinant adeno-associated virus type 2 (AAV2)-PRR-small hairpain RNA (shRNA)-mediated gene transduction, caused a significant increase in mean arterial pressure (MAP) in the SHR (shRNA, 173±5; Control, 151±6 mm Hg) but not in Wistar Kyoto rats (shRNA, 108±7; Control, 106±6 mm Hg). The MAP elevation in the SHR was associated with decreased inflammatory markers tumor necrosis factor-α, interleukin-6, C-C motif ligand 5, and their transcription factor, nuclear factor-κB. Consistent with the pressor effects of the PRR knockdown, acute bilateral NTS injection of human renin (2 pmol/side) decreased MAP and heart rate (HR) in SHR (ΔMAP, −38±4 mm Hg; Δheart rate, −40±10 bp...