Angiotensin Hypertension Research Articles

Gradual hypertensive response in aortic alterations and myocardial inflammatory activation in progressing HFpEF in mice

Abstract Introduction Hypertension is the most common comorbidity in patients affected by heart failure with preserved ejection fraction (HFpEF). Early effects of pressure overload and its contribution to the gradual development of cardiac and vascular pathology leading to HFpEF are not well recognized, as patients are diagnosed when the disease has already advanced and show symptoms. Several hypertensive HFpEF mouse models possessing the hallmarks of the clinical-like phenotype are available. Nonetheless, initial and gradual pathological manifestations of hypertensive HFpEF have not been comprehensively described. Purpose This study aimed to investigate the gradual progression of HFpEF phenotype development in mice from the early manifestation of cardiac and vascular pathology to global cardiac dysfunction to multiorgan syndrome in response to hypertension. Methods Hypertensive HFpEF was induced by angiotensin II infusion in C57BL/6JOlaHsd 18-20-week-old male mice that were given low, moderate and high doses (0.5mg/kg/day - 1.5 mg/kg/day) subcutaneously for 4 weeks. Cardiac physiology and alterations in haemodynamics were assessed with echocardiography of heart and aorta, weekly ECG monitoring, and blood pressure measurements from the mouse tail. Extensive histology and immunohistochemistry analyses of cardiac tissue, microvasculature, lungs and kidneys were performed. Results In the low dose group, loss of aortic wall flexibility and presence of aortic root dilatation were detected. This group also demonstrated initiation of concentric remodelling process with the upsurge in macrophage infiltration in myocardium, but the signs of diastolic dysfunction were not yet present. The high dose group exhibited characteristic HFpEF features with diastolic dysfunction, left ventricular hypertrophy and fibrosis. Pathology in cardiac conduction system was noticed in all groups, with prominent ECG waveform abnormalities already on week one. However, only the high dose group experienced non-recovery in impulse propagation, accompanied by significant prolongation of ventricular depolarization. Conclusion This study demonstrates that change in aortic root dimensions and aortic wall dynamics are the first hypertension-sensitive alterations together with myocardial inflammatory cell infiltration that may contribute to myocardial remodelling and subsequent development of HFpEF and systemic effects. Hypertensive angiotensin II-induced HFpEF is a relevant mouse model, recapitulating not only hallmarks of cardiac pathology but also an extensive range of vascular and multiorgan alterations, demonstrating similarities with the clinical phenotype.

Coupling of phagocytic NADPH oxidase activity and mitochondrial superoxide production.

Superoxide radical plays an important role in redox cell signaling and physiological processes; however, overproduction of superoxide or insufficient activity of antioxidants leads to oxidative stress and contributes to the development of pathological conditions such as endothelial dysfunction and hypertension. Meanwhile, the studies of superoxide in biological systems represent unique challenges associated with short lifetime of superoxide, insufficient reactivity of the superoxide probes, and lack of site-specific detection of superoxide. In this work we have developed 15N-and deuterium-enriched spin probe 15N-CAT1H for high sensitivity and site-specific detection of extracellular superoxide. We have tested simultaneous tracking of extracellular superoxide by 15N-CAT1H and intramitochondrial superoxide by conventional 14N-containing spin probe mitoTEMPO-H in immune cells isolated from spleen, splenocytes, under basal conditions or stimulated with inflammatory cytokines IL-17A and TNFα, NADPH oxidase activator PMA, or treated with inhibitors of mitochondrial complex I rotenone or complex III antimycin A. 15N-CAT1H provides two-fold increase in sensitivity and improves detection since EPR spectrum of 15N-CAT1 nitroxide does not overlap with biological radicals. Furthermore, concurrent use of cell impermeable 15N-CAT1H and mitochondria-targeted 14N-mitoTEMPO-H allows simultaneous detection of extracellular and mitochondrial superoxide. Analysis of IL-17A- and TNFα-induced superoxide showed parallel increase in 15N-CAT1 and 14N-mitoTEMPO signals suggesting coupling between phagocytic NADPH oxidase and mitochondria. The interplay between mitochondrial superoxide production and activity of phagocytic NADPH oxidase was further investigated in splenocytes isolated from Sham and angiotensin II infused C57Bl/6J and Nox2KO mice. Angiotensin II infusion in wild-type mice increased the extracellular basal splenocyte superoxide which was further enhanced by complex III inhibitor antimycin A, mitochondrial uncoupling agent CCCP and NADPH oxidase activator PMA. Nox2 depletion attenuated angiotensin II mediated stimulation and inhibited both extracellular and mitochondrial PMA-induced superoxide production. These data indicate that splenocytes isolated from hypertensive angiotensin II-infused mice are “primed” for enhanced superoxide production from both phagocytic NADPH oxidase and mitochondria. Our data demonstrate that novel 15N-CAT1H provides high sensitivity superoxide measurements and combination with mitoTEMPO-H allows independent and simultaneous detection of extracellular and mitochondrial superoxide. We suggest that this new approach can be used to study the site-specific superoxide production and analysis of important sources of oxidative stress in cardiovascular conditions.

Ang II-Induced Hypertension Exacerbates the Pathogenesis of Tuberculosis.

It has been known that infection plays a role in the development of hypertension. However, the role of hypertension in the progression of infectious diseases remain unknown. Many countries with high rates of hypertension show geographical overlaps with those showing high incidence rates of tuberculosis (TB). To explore the role of hypertension in tuberculosis, we compared the effects of hypertension during mycobacterial infection, we infected both hypertensive Angiotensin II (Ang II) and control mice with Mycobacterium tuberculosis (Mtb) strain H37Ra by intratracheal injection. Ang II-induced hypertension promotes cell death through both apoptosis and necrosis in Mtb H37Ra infected mouse lungs. Interestingly, we found that lipid accumulation in pulmonary tissues was significantly increased in the hypertension group compared to the normal controls. Ang II-induced hypertension increases the formation of foamy macrophages during Mtb infection and it leads to cell death. Moreover, the hypertension group showed more severe granuloma formation and fibrotic lesions in comparison with the control group. Finally, we observed that the total number of mycobacteria was increased in the lungs in the hypertension group compared to the normal controls. Taken together, these results suggest that hypertension increases intracellular survival of Mtb through formation of foamy macrophages, resulting in severe pathogenesis of TB.

Repurposing Candesartan Cilexetil as Antibacterial Agent for MRSA Infection.

Staphylococcus aureus is an important pathogen causing hospital-acquired infections. Methicillin-resistant S. aureus (MRSA), biofilms, and persisters are highly tolerant to traditional antibiotics and make it difficult to treat. Therefore, new antimicrobial agents are urgently needed to treat hard-to-eradicate diseases caused by this bacterium. In this study, candesartan cilexetil (CC), an angiotensin hypertension drug, had strong antimicrobial activity against S. aureus with minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of 8–16 μg/ml and 16–32 μg/ml. CC exhibited limited cytotoxicity and low potential to induce drug resistance. In addition, it showed a synergistic antibacterial effect when combined with gentamicin and tobramycin. The effective concentrations to inhibit MRSA biofilm formation were 16–64 μg/ml, and intractable persisters were killed at 4–8 × MIC. Through the analysis of its mechanism of action, it was evident that the membrane permeability was disrupted as well as the cell structure was damaged. Furthermore, we demonstrated that CC had antibacterial effects in vivo in MRSA-infected murine skin abscess models. In conclusion, these results imply that CC might be a potential antibacterial agent for the treatment of S. aureus-associated infections.

Short-term hypoxia upregulated Mas receptor expression to repress the AT1 R signaling pathway and attenuate Ang II-induced cardiomyocyte apoptosis.

Hypertension-stimulated cardiac hypertrophy and apoptosis play critical roles in the progression of heart failure. Our previous study suggested that hypertensive angiotensin II (Ang II) enhanced insulin-like growth factor receptor II (IGF-IIR) expression and cardiomyocyte apoptosis, which are involved JNK activation, sirtuin1 (SIRT1) degradation, and heat-shock transcription factor 1 (HSF1) acetylation. Moreover, previous studies have implied that short-term hypoxia (STH) might exert cardioprotective effects. However, the effects of STH on Ang II-induced cardiomyocyte apoptosis remain unknown. In this study, we found that STH reduced myocardial apoptosis caused by Ang II via upregulation of the Mas receptor (MasR) to inhibit the AT1 R signaling pathway. STH activates MasR to counteract the Ang II pro-apoptotic signaling cascade by inhibiting IGF-IIR expression via downregulation of JNK activation and reduction of SIRT1 degradation. Hence, HSF could remain deacetylated, and repress IGF-IIR expression. These effects decrease the activation of downstream pro-apoptotic and hypertrophic cascades and protect cardiomyocytes from Ang II-induced injury. In addition, we also found that silencing MasR expression enhanced Ang II-induced cardiac hypertrophy and the apoptosis signaling pathway. These findings suggest a critical role for MasR in cardiomyocyte survival. Altogether, our findings indicate that STH protects cardiomyocytes from Ang II-stimulated apoptosis. The protective effects of STH are associated with the upregulation of MasR to inhibit AT1 R signaling. STH could be a potential therapeutic strategy for cardiac diseases in hypertensive patients.

Inhibition of HSF2 SUMOylation via MEL18 upregulates IGF-IIR and leads to hypertension-induced cardiac hypertrophy

Cardiac hypertrophy is a major characteristic of early-stage hypertension-related heart failure. We have found that the insulin-like growth factor receptor II (IGF-IIR) signaling was critical for hypertensive angiotensin II-induced cardiomyocyte hypertrophy and apoptosis. Moreover, this IGF-IIR signaling was elegantly modulated by the heat shock transcription factors (HSFs) during heart failure. However, the detailed mechanism by which HSFs regulates IGF-IIR during hypertension-induced cardiac hypertrophy remains elusive. In this study, we found that heat shock transcription factor 2 (HSF2) activated IGF-IIR to induce cardiac hypertrophy for hypertension-induced heart failure. The transcriptional activity of HSF2 appeared to be primarily mediated by SUMOylation via conjugation with small ubiquitin-like modifier-1 (SUMO-1). The SUMOylation of HSF2 was severely attenuated by MEL18 (also known as polycomb group ring finger 2 or PCGF2) in the heart of spontaneously hypertensive rats (SHR). Inhibition of HSF2 SUMOylation severely induced cardiac hypertrophy via IGF-IIR-mediated signaling in hypertensive rats. Angiotensin II receptor type I blocker (ARB) treatment in spontaneously hypertensive rats restored HSF2 SUMOylation and alleviated the cardiac defects. Thus, our study uncovered a novel MEL18-SUMO-1-HSF2-IGF-IIR pathway in the heart that profoundly influences cardiac hypertrophy for hypertension-induced heart failure.

Orally Active Epoxyeicosatrienoic Acid Analogs.

Biologically active epoxyeicosatrienoic acid (EET) regioisomers are synthesized from arachidonic acid by cytochrome P450 epoxygenases of endothelial, myocardial, and renal tubular cells. EETs relax vascular smooth muscle and decrease inflammatory cell adhesion and cytokine release. Renal EETs promote sodium excretion and vasodilation to decrease hypertension. Cardiac EETs reduce infarct size after ischemia-reperfusion injury and decrease fibrosis and inflammation in heart failure. In diabetes, EETs improve insulin sensitivity, increase glucose tolerance, and reduce the renal injury. These actions of EETs emphasize their therapeutic potential. To minimize metabolic inactivation, 14,15-EET agonist analogs with stable epoxide bioisosteres and carboxyl surrogates were developed. In preclinical rat models, a subset of agonist analogs, termed EET-A, EET-B, and EET-C22, are orally active with good pharmacokinetic properties. These orally active EET agonists lower blood pressure and reduce cardiac and renal injury in spontaneous and angiotensin hypertension. Other beneficial cardiovascular actions include improved endothelial function and cardiac antiremodeling actions. In rats, EET analogs effectively combat acute and chronic kidney disease including drug- and radiation-induced kidney damage, hypertension and cardiorenal syndrome kidney damage, and metabolic syndrome and diabetes nephropathy. The compelling preclinical efficacy supports the prospect of advancing EET analogs to human clinical trials for kidney and cardiovascular diseases.

P53-mediated miR-18 repression activates HSF2 for IGF-IIR-dependent myocyte hypertrophy in hypertension-induced heart failure

Hypertension-induced cardiac hypertrophy and attenuated cardiac function are the major characteristics of early stage heart failure. Cardiomyocyte death in pathological cardiac conditions is the primary cause of heart failure and mortality. Our previous studies found that heat shock factor 1 (HSF1) protected cardiomyocytes from death by suppressing the IGF-IIR signaling pathway, which is critical for hypertensive angiotensin II-induced cardiomyocyte apoptosis. However, the role of heat shock factor 2 (HSF2) in hypertension-induced cardiac hypertrophy is unknown. We identified HSF2 as a miR-18 target for cardiac hypertrophy. p53 activation in angiotensin II (ANG II)-stimulated NRVMs is responsible for miR-18 downregulation both in vitro and in vivo, which triggers HSF2 expression and the activation of IGF-IIR-induced cardiomyocyte hypertrophy. Finally, we provide genetic evidence that miR-18 is required for cardiomyocyte functions in the heart based on the gene transfer of cardiac-specific miR-18 via adenovirus-associated virus 2 (AAV2). Transgenic overexpression of miR-18 in cardiomyocytes is sufficient to protect against dilated cardiomyopathy during hypertension-induced heart failure. Our results demonstrated that the p53-miR-18-HSF2-IGF-IIR axis was a critical regulatory pathway of cardiomyocyte hypertrophy in vitro and in vivo, suggesting that miR-18 could be a therapeutic target for the control of cardiac functions and the alleviation of cardiomyopathy during hypertension-induced heart failure.

Association between angiotensin converting enzyme gene polymorphism and hypertension with abnormal savda in Uyghur people

Association between angiotensin converting enzyme gene polymorphism and hypertension with abnormal savda in Uyghur people

Abstract 001: Hypertension Induces Heightened Activity of the Adaptive Immune System

Adaptive immunity plays a key role in the pathogenesis of hypertension, but how does hypertension affect immunity? To study this, splenic dendritic cells (DC) and peritoneal macrophages were isolated from normotensive and hypertensive angiotensin II (AngII)-infused C57BL6/J mice (490 ng/kg/min, 2 wk). These antigen presenting cells (APCs) were loaded with ovalbumin (OVA) or the OVA MHC class I epitope SIINFEKL (SKL) for 3h. Then, splenocytes from OT-I mice, containing OVA-specific, CD8 + T cells (OT-I cells), were added for 4h. Flow cytometry showed significantly more activated T cells expressing CD69 when stimulated with APCs from AngII-treated mice than equivalent cells from naïve mice (As example, DC+OVA: 2.9 ± 0.4% vs. 1.8 ± 0.3% ,P<0.05; DC+SKL: 13.9 ± 0.9 % vs. 7.4 ± 1.1%, P<0.01;). To study antigen presentation in vivo, we immunized AngII and sham treated mice with OVA and adjuvant. Consistently more OVA-specific CD8 + T cells were induced in the blood (2.7 ± 0.2% vs. 1.2 ± 0.4%, P<0.05) and the spleen (2.6 ± 0.3% vs. 1.5 ± 0.2%, P<0.05) of hypertensive mice vs. sham when measured by flow using a H-2k b -SKL tetramer. RIP-mOVA mice were also used to study if hypertension affects APC cross-presentation of self-antigens. This transgenic mouse line expresses membrane-bound OVA in pancreatic islet β cells and kidney proximal tubular cells. When OT-I cells (5x10 6 ) are injected into RIP-mOVA mice, they activate by cross-presentation of OVA and cause insulitis and diabetes. RIP-mOVA mice were made hypertensive with either AngII or L-NAME. When OT-I cells were infused into hypertensive RIP-mOVA mice, they rapidly developed much higher blood glucose levels as compared to equivalently treated normotensive RIP-mOVA mice. For example, comparing mice 3 weeks after AngII and 1 wk after OT-I cells to normotensive mice 1 wk after OT-I cells, blood glucose was 331 ± 47 mg/dl in the hypertensive mice vs. 168 ± 39 mg/dl in the normotensive controls. Also, far more pancreatic islets were infiltrated by T cells in the hypertensive mice (AngII 78%, 31 of 40; L-NAME 72%, 21 of 29; control 13%, 10 of 75). In conclusion, hypertension itself is associated with higher activity of APC presentation of foreign and self-antigens which may explain why hypertension induces inflammation.

Abstract 002: Dynamic T Cell-Antigen Presenting Cell Interactions and Direct T Cell Activation Within the Vascular Wall During Hypertension

T cells are now known to be vital to the development of experimental hypertension. Hypertension is associated with significant accumulation of T cells into the perivascular fat surrounding the aorta and renal vasculature. While a hypertension-specific neoantigen has been implicated in T cell activation, it is not known whether vascular-infiltrating T cells recognize and are locally activated by an antigen within the vessel wall. We developed live-cell imaging of explanted aortas to identify whether cognate antigens are presented to T cells within the vessel wall of hypertensive mice, evidenced by slower T cell velocities and a greater number of T cells interacting with antigen presenting cells (APCs). Splenic T cells were isolated from normotensive vehicle-treated (nT cells) and hypertensive angiotensin II (Ang II)-infused (0.7mg/kg/day; 14 days; hT cells) C57BL6/J mice. Following anti-CD3/CD28 stimulation (48 hours), cells were fluorescently labelled and co-incubated simultaneously (16 hours) with explanted aorta from normotensive or hypertensive CD11c-YFP mice, where APCs are fluorescently labelled. In CD11c-YFP mouse aorta alone, we detected a ~2-fold increase in CCR5 ligand (CCL3, CCL4 and CCL5) secretion from hypertensive mouse aorta compared to vehicle-treated mouse aorta (*P<0.05; n = 4). Using 2-photon microscopy, we observed a greater number (~2-fold) of hT cells compared to nT cells within Ang II-infused mouse aorta (390 ± 113 Vs 198 ± 49). Importantly, time-lapse recordings of hypertensive mouse aorta revealed hT cells exhibited significantly slower velocity (hT cells 2.0 μm/min Vs nT cells 4.8 μm/min; **P<0.01, n=8-12), and a greater proportion of interactions with APCs (hT cells 4.4 ± 1.1 Vs nT cells 0.8 ± 0.4%). Moreover, activation of local vascular T cells by incubating hypertensive aorta with anti-CD3/CD28 antibodies (16 hours) augmented Ang II-induced endothelial dysfunction (67.5 ± 2.0 Vs Ang II alone 54.5 ± 3.7% maximal relaxation). We have the first evidence that vascular-infiltrating T cells are presented with cognate antigens by APCs within the vessel wall during hypertension; direct activation of these T cell infiltrates further impairs endothelial function, which may promote the development of hypertension.

ANG II promotes IGF-IIR expression and cardiomyocyte apoptosis by inhibiting HSF1 via JNK activation and SIRT1 degradation.

Hypertension-induced cardiac hypertrophy and apoptosis are major characteristics of early-stage heart failure. Our previous studies found that the activation of insulin-like growth factor receptor II (IGF-IIR) signaling was critical for hypertensive angiotensin II (ANG II)-induced cardiomyocyte apoptosis. However, the detailed mechanism by which ANG II regulates IGF-IIR in heart cells remains elusive. In this study, we found that ANG II activated its downstream kinase JNK to increase IGF-IIR expression through the ANG II receptor angiotensin type 1 receptor. JNK activation subsequently led to sirtuin 1 (SIRT1) degradation via the proteasome, thus preventing SIRT1 from deacetylating heat-shock transcription factor 1 (HSF1). The resulting increase in the acetylation of HSF1 impaired its ability to bind to the IGF-IIR promoter region (nt -748 to -585). HSF1 protected cardiomyocytes by acting as a repressor of IGF-IIR gene expression, and ANG II diminished this HSF1-mediated repression through enhanced acetylation, thus activating the IGF-IIR apoptosis pathway. Taken together, these results suggest that HSF1 represses IGF-IIR gene expression to protect cardiomyocytes. ANG II activates JNK to degrade SIRT1, resulting in HSF1 acetylation, which induces IGF-IIR expression and eventually results in cardiac hypertrophy and apoptosis. HSF1 could be a valuable target for developing treatments for cardiac diseases in hypertensive patients.

A Review of the Use of Angiotensin Receptor Blockers for the Prevention of Cardiovascular Events in Patients with Essential Hypertension Without Compelling Indications

To review the role of angiotensin receptor blockers (ARBs) for the prevention of cardiovascular events in patients with essential hypertension without other compelling indications. Peer-reviewed clinical trials, review articles, and relevant treatment guidelines were identified from MEDLINE and Current Content database (both 1966-November 15, 2012) using the search terms angiotensin receptor blockers (ARBs), azilsartan, candesartan, eprosartan, irbesartan, losartan, olmesartan, telmisartan, valsartan, hypertension, myocardial infarction, stroke, heart failure, and cardiovascular outcomes. Results were limited to human trials published in English. Citations from articles were also reviewed for additional references. The focus was on clinical trials evaluating cardiovascular end points of ARBs used in patients with essential hypertension without compelling indications. Data supporting the use of ARBs for reducing cardiovascular events in patients with essential hypertension without compelling indications are inconsistent. To date, only candesartan and losartan have shown a significant reduction in cardiovascular morbidity within this sizable subgroup of patients. In the Study on Cognition and Prognosis in the Elderly (SCOPE) trial, candesartan showed a 27.8% reduction in nonfatal stroke versus placebo (95% CI 1.3-47.2; p = 0.04). Moreover, losartan demonstrated a decrease in all cardiovascular events compared to atenolol in the Cardiovascular Morbidity and Mortality in the Losartan Intervention for Endpoint Reduction in Hypertension (LIFE) study (RR 0.87; 95% CI 0.77-0.98; p = 0.021). Data supporting the use of ARBs for reducing cardiovascular events in patients with essential hypertension without compelling indications are limited and inconclusive. More studies are needed before ARBs can be routinely recommended as first-line therapy for hypertension management in patients without other compelling indications.

Augmented response of renal sympathetic nerve single units to chemoreceptor stimuli in rabbits with angiotensin induced hypertension

We examined the effect of angiotensin (AngII) hypertension on the activity of post‐ganglionic renal sympathetic units to determine whether elevated whole renal nerve activity is due to recruitment or increased firing frequency. Rabbits were treated with AngII for 4 weeks (50ng/kg/min, high dose) or for 8 weeks (20ng/kg/min, low dose) and then chloralose‐urethane anesthetized to test unitary responses to altered chemoreceptor activity. Units were detected from multi‐unit recordings using a novel algorithm that separated units by action potential shape characteristics using templates that matched spikes within a prescribed SD. Resting firing frequency was similar in sham (1.0±0.04 spikes/s, n=144) and high AngII rabbits (1.1±0.04 spikes/s, n=112) but was lower with low AngII (0.65±0.04 spikes/s, n=149). Firing frequency increased markedly to hypoxia (8% O2) in the high AngII group (+103%) but only by +39% in low AngII and +82% in sham group. The increase in firing rate with hypercapnia (8% CO2) was also greatest in the high AngII group whilst 100% O2 suppressed unitary firing in high AngII and sham groups. This study suggests that increases in sympathetic outflow in low dose AngII hypertension are most likely due to recruitment of individual neurons but high dose AngII markedly increases firing frequency to chemoreceptor stimuli. Supported by grants from National Health and Medical Research Council of Australia.

Screening for primary aldosteronism in a primary care unit

Primary aldosteronism (PA) is a common cause of secondary hypertension but the reported prevalence varies. Few studies have been carried out in primary care. We investigated the prevalence of PA by screening with the aldosterone to renin ratio (ARR). Patients with hypertension were recruited from a primary care unit and investigated in a university hospital setting. Of 235 patients asked to participate 77% accepted. Antihypertensive medication apart from amiloride and spironolactone was maintained. The cut-off level for a positive ARR was lower than in clinical practice (> 50 pmol/ng with aldosterone > 350 pmol/l) to adjust for any suppressive effects of medication. A positive ARR was followed by a confirmatory evaluation. The frequency of confirmed PA was 1.6% and including cases with a positive ARR who refused further investigation it would be 3.3% at most. In primary hypertension angiotensin receptor blockers, angiotensin-converting enzyme inhibitors and thiazide diuretics markedly suppressed the ARR by increasing renin levels. The detection rate of PA in our study is in the lower part of the wide range shown in previous studies. Larger population studies are needed to establish the true prevalence in primary care. Future studies may clarify if the present cut-off levels allow detection of very mild PA.

Candesartan in the treatment of hypertension: what have we learnt in the last decade?

Introduction:Although all of the first-line antihypertensive drugs effectively reduce blood pressure, there are some conditions that may favor the use of angiotensin receptor blockers over others, such as left ventricular hypertrophy, microalbuminuria, renal dysfunction, diabetes, or metabolic syndrome, among others.Areas covered:This manuscript reviewed the data supporting the use of candesartan cilexetil in hypertensive population with a special focus on its efficacy and safety. For this purpose, a search on MEDLINE and EMBASE databases was performed. The MEDLINE and EMBASE search included both medical subject headings (MeSH) and keywords including: candesartan OR angiotensin receptor blockers OR renin angiotensin system AND hypertension treatment. References of the retrieved articles were also screened for additional studies. There were no language restrictions.Expert opinion:Candesartan, a long-acting angiotensin receptor antagonist, has been shown to be an effective and well-tolerated therapy in the entire spectrum of hypertensive patients, including those at higher risk, such as those with diabetes, metabolic syndrome, left ventricular hypertrophy, or microalbuminuria.

Development of Epoxyeicosatrienoic Acid Analogs with in Vivo Anti-Hypertensive Actions

Epoxyeicosatrienoic acids (EETs) contribute importantly to the regulation of vascular tone and blood pressure control. The purpose of this study was to develop stable EET analogs and test their in vivo blood pressure lowering effects in hypertensive rats. Using the pharmacophoric moiety of EETs, ether EET analogs were designed with improved solubility and resistance to auto-oxidation and metabolism by soluble epoxide hydrolase. Ether EET analogs were chosen based on their ability to dilate afferent arterioles and subsequently tested for blood pressure lowering effects in rodent models of hypertension. Initially, 11,12-ether-EET-8-ZE failed to lower blood pressure in angiotensin hypertension or spontaneously hypertensive rats (SHR). Esterification of the carboxylic group of 11,12-ether-EET-8-ZE prevented blood pressure increase in SHR when injected at 2 mg/day for 12 days (MAP Δ change at day 8 of injection was −0.3 ± 2 for treated and 12 ± 1 mmHg for control SHR). Amidation of the carboxylic group with aspartic acid produced another EET analog (NUDSA) with a blood pressure lowering effect when injected at 3 mg/day in SHR for 5 days. Amidation of the carboxylic group with lysine amino acid produced another analog with minimal blood pressure lowering effect. These data suggest that esterification of the carboxylic group of 11,12-ether-EET-8-ZE produced the most effective ether-EET analog in lowering blood pressure in SHR and provide the first evidence to support the use of EET analogs in treatment of cardiovascular diseases.

The Soluble Epoxide Hydrolase Inhibitor AR9281 Decreases Blood Pressure, Ameliorates Renal Injury and Improves Vascular Function in Hypertension.

Soluble epoxide hydrolase inhibitors (sEHIs) are demonstrating promise as potential pharmaceutical agents for the treatment of cardiovascular disease, diabetes, inflammation, and kidney disease. The present study determined the ability of a first-in-class sEHI, AR9281, to decrease blood pressure, improve vascular function, and decrease renal inflammation and injury in angiotensin hypertension. Rats were infused with angiotensin and AR9281 was given orally during the 14-day infusion period. Systolic blood pressure averaged 180 ± 5 mmHg in vehicle treated and AR9281 treatment significantly lowered blood pressure to 142 ± 7 mmHg in angiotensin hypertension. Histological analysis demonstrated decreased injury to the juxtamedullary glomeruli. Renal expression of inflammatory genes was increased in angiotensin hypertension and two weeks of AR9281 treatment decreased this index of renal inflammation. Vascular function in angiotensin hypertension was also improved by AR9281 treatment. Decreased afferent arteriolar and mesenteric resistance endothelial dependent dilator responses were ameliorated by AR9281 treatment of angiotensin hypertensive rats. These data demonstrate that the first-in-class sEHI, AR9281, lowers blood pressure, improves vascular function and reduces renal damage in angiotensin hypertension.

The role of aldosterone in mediating the dependence of angiotensin hypertension on IL-6

Knockout (KO) of IL-6 has been shown to attenuate ANG II hypertension, and mineralocorticoid receptors (MR) have been reported to contribute to the increase in IL-6 during acute ANG II infusion. This study determined whether that MR action is sustained with chronic ANG II infusion and whether it plays a role in mediating ANG II hypertension. ANG II infusion (90 ng/min) increased plasma IL-6 from 1.6 +/- 0.6 to 22.7 +/- 2.2 and 19.9 +/- 3.2 pg/ml on days 7 and 14, respectively, and chronic MR blockade with spironolactone attenuated that only at day 7 (7.2 +/- 2.2 pg/ml). ANG II increased MAP (19 h/day with telemetry) approximately 40 mmHg, but in ANG II+spironolactone mice (25 or 50 mg*kg(-1)*day(-1)), mean arterial pressure (MAP) was not significantly different despite a tendency for lower pressure the first 6 days. To isolate further the mineralocorticoid link to IL-6 and blood pressure, DOCA-salt hypertension was induced in IL-6 KO and wild-type (WT) mice. Plasma IL-6 increased from 4.1 +/- 1.7 to 34.5 +/- 7.0 pg/ml by day 7 of DOCA treatment in the WT mice but was back to control levels by day 14. An IL-6 bioassay using the murine B9, B-cell hybridoma cell line demonstrated that plasma IL-6 measurements reflected actual IL-6 bioactivity. The hypertension was not different and virtually superimposable in WT vs. IL-6 KO mice, averaging 145 +/- 2 and 144 +/- 3 mmHg, respectively. Both experiments confirm chronic stimulation of IL-6 by mineralocorticoids but show that it is transient. In addition, IL-6 was not required for mineralocorticoid hypertension. This suggests that aldosterone contributes to the increase in plasma IL-6 in the early stage of ANG II hypertension but that the blood pressure actions of IL-6 in that model are linked most likely to ANG II rather than aldosterone.

Secreted Protein Acidic and Rich in Cysteine Deficiency Ameliorates Renal Inflammation and Fibrosis in Angiotensin Hypertension

The matricellular protein secreted protein acidic and rich in cysteine (SPARC) modulates cell adhesion, proliferation, matrix deposition, and tissue remodeling. SPARC has been shown to regulate the expression of collagen type I and transforming growth factor-beta1 in mesangial cells and to be highly expressed during tubulointerstitial fibrosis in rat angiotensin (ANG) II infusion models. We hypothesized that SPARC is a downstream effector of ANG II and that loss of host SPARC function provides a protective effect on renal damage and fibrosis associated with ANG II hypertension. Our results revealed that cultured primary mesangial cells displayed a concentration-dependent increase in SPARC expression in response to ANG II. After a 14-day chronic infusion of ANG II, hypertensive SPARC-null mice exhibited significantly attenuated levels of urinary and renal indicators of oxidative stress and inflammation and decreased renal perivascular and tubulointerstitial fibrosis relative to wild-type hypertensive controls. Moreover, the observed renal protective changes in SPARC-null mice were found to be independent of blood pressure. These results identify SPARC as an effector of ANG II signaling and suggest an important role for SPARC in mediating ANG II-induced oxidative stress, inflammation, and fibrosis.