Eprosartan improves cardiac performance, reduces cardiac hypertrophy and mortality and downregulates myocardial monocyte chemoattractant protein-1 and inflammation in hypertensive heart disease

Adaptive and maladaptive roles of different angiotensin receptors in the development of cardiac hypertrophy and heart failure

Angiotensin II (Ang II) is formed by the action of angiotensin-converting enzyme (ACE) in the renin-angiotensin system. This hormone is known to induce cardiac hypertrophy and heart failure and its actions are mediated by the interaction of both pro- and antihypertrophic Ang II receptors (AT1R and AT2R). Ang II is also metabolized by ACE 2 to Ang-(1-7), which elicits the activation of Mas receptors (MasR) for inducing antihypertrophic actions. Since heart failure under different pathophysiological situations is preceded by adaptive and maladaptive cardiac hypertrophy, we have reviewed the existing literature to gain some information regarding the roles of AT1R, AT2R, and MasR in both acute and chronic conditions of cardiac hypertrophy. It appears that the activation of AT1R may be involved in the development of adaptive and maladaptive cardiac hypertrophy as well as subsequent heart failure because both ACE inhibitors and AT1R antagonists exert beneficial effects. On the other hand, the activation of both AT2R and MasR may prevent the occurrence of maladaptive cardiac hypertrophy and delay the progression of heart failure, and thus therapy with different activators of these antihypertrophic receptors under chronic pathological stages may prove beneficial. Accordingly, it is suggested that a great deal of effort should be made to develop appropriate activators of both AT2R and MasR for the treatment of heart failure subjects.

Inflammatory Mechanisms in Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is now the most common form of heart failure and a significant public health concern for which limited effective therapies exist. Inflammation triggered by comorbidity burden is a critical element of HFpEF pathophysiology. Here, we discuss evidence for comorbidity-driven systemic and myocardial inflammation and the mechanistic role of inflammation in pathological myocardial remodeling in HFpEF.

The Novel AT2 Receptor Agonist β-Pro7-AngIII Exerts Cardiac and Renal Anti-Fibrotic and Anti-Inflammatory Effects in High Salt-Fed Mice

A high salt (HS) diet is associated with an increased risk for cardiovascular diseases (CVDs) and fibrosis is a key contributor to the organ dysfunction involved in CVDs. The activation of the renin angiotensin type 2 receptor (AT₂R) has been considered as organ protective in many CVDs. However, there are limited AT₂R-selective agonists available. Our first reported β-substituted angiotensin III peptide, β-Pro⁷-AngIII, showed high selectivity for the AT₂R. In the current study, we examine the potential anti-fibrotic and anti-inflammatory effects of this novel AT₂R-selective peptide on HS-induced organ damage. FVB/N mice fed with a 5% HS diet for 8 weeks developed cardiac and renal fibrosis and inflammation, which were associated with increased TGF-β1 levels in heart, kidney and plasma. Four weeks' treatment (from weeks 5-8) with β-Pro⁷-AngIII inhibited the HS-induced cardiac and renal fibrosis and inflammation. These protective effects were accompanied by reduced local and systemic TGF-β1 as well as reduced cardiac myofibroblast differentiation. Importantly, the anti-fibrotic and anti-inflammatory effects caused by β-Pro⁷-AngIII were attenuated by the AT₂R antagonist PD123319. These results demonstrate, for the first time, the cardio- and reno-protective roles of the AT₂R-selective β-Pro⁷-AngIII, highlighting it as an important therapeutic that can target the AT₂R to treat end-organ damage.

Immunomodulatory Activity of the Most Commonly Used Antihypertensive Drugs-Angiotensin Converting Enzyme Inhibitors and Angiotensin II Receptor Blockers

This review article is focused on antihypertensive drugs, namely angiotensin converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB), and their immunomodulatory properties reported in hypertensive patients as well as in experimental settings involving studies on animal models and cell lines. The immune regulatory action of ACEI and ARB is mainly connected with the inhibition of proinflammatory cytokine secretion, diminished expression of adhesion molecules, and normalization of CRP concentration in the blood plasma. The topic has significant importance in future medical practice in the therapy of patients with comorbidities with underlying chronic inflammatory responses. Thus, this additional effect of immune regulatory action of ACEI and ARB may also benefit the treatment of patients with metabolic syndrome, allergies, or autoimmune disorders.

The promoting role of Cx43 on the proliferation and migration of arterial smooth muscle cells for angiotensin II-dependent hypertension

BACKGROUND

Recent studies have shown that endothelin-1 and angiotensin II (AngII) can increase gap junctional intercellular communication (GJIC) by activating Mitogen-activated protein kinases (MAPKs) pathway. However, not only the precise interaction of AngII with Connexin43(Cx43) and the associated functions remain unclear, but also the regulatory role of Cx43 on the AngII-mediated promotion proliferation and migration of VSMCs is poorly understood.

MATERIAL AND METHODS

Our research applicated pressure myography measurements, immunofluorescence and Western blot analyses to investigate the changes in physiological indicators in spontaneously hypertensive rats (SHRs) and AngII-stimulated proliferation and migration of A7r5 SMCs(Rat vascular smooth muscle cells). The aim was to elucidate the role of CX43 in hypertension induced by AngII.

RESULTS

Chronic ramipril (angiotensin converting enzyme inhibitor) management for SHRs significantly attenuated blood pressure and blood vessel wall thickness, also reduced contraction rate in the cerebral artery. The cerebral artery contraction rates, mRNA and protein expression of Cx43, osteopontin (OPN) and proliferating cell nuclear antigen (PCNA) protein expression in the SHR + ramipril and SHR + ramipril + carbenoxolone (CBX, Cx43 specific blocker) groups were significantly lower than those in the SHR group. Cx43 protein expression and Ser368 phosphorylated Cx43 protein levels increased significantly in AngII-stimulated A7r5 cells. However, the levels of phosphorylated Cx43 decreased after pre-treatment with candesartan (AT1 receptor blocker), GF109203X (protein kinase C (PKC) blocker) and U0126 (mitogen-activated protein kinases/extracellular signal-regulated kinase1/2(MEK/ERK1/2)-specific blocker) in AngII-stimulated A7r5 cells. Cx43 was widely distributed in the cell membrane, nucleus, and cytoplasm of the SMCs. Furthermore, pre-treatment of the AngII- stimulated A7r5 cells with Gap26 (Cx43 blocker) significantly inhibited cell migration and decreased the expression levels of MEK1/2, ERK1/2, P-MEK1/2, and P-ERK1/2.

CONCLUSION

Our research confirms that Cx43 plays an important role in the regulation of proliferation and migration of VSMCs via MEK/ERK and PKC signal pathway in AngII-dependent hypertension.

Angiotensin Type 1 Receptor Blockers in Heart Failure

Homeostasis in the cardiovascular system is maintained by physiological functions of the Renin Angiotensin Aldosterone System (RAAS). In pathophysiological conditions, over activation of RAAS leads to an increase in the concentration of Angiotensin II (AngII) and over activation of Angiotensin Type 1 Receptor (AT1R), resulting in vasoconstriction, sodium retention and change in myocyte growth. It causes cardiac remodeling in the heart which results in left ventricular hypertrophy, dilation and dysfunction, eventually leading to Heart Failure (HF). Inhibition of RAAS using angiotensin converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARBs) has shown to significantly reduce morbidity and mortality due to HF. ACEi have been shown to have higher drug withdrawal rates due to discomfort when compared to ARBs; therefore, ARBs are the preferred choice of physicians for the treatment of HF in combination with other anti-hypertensive agents. Currently, eight ARBs have been approved by FDA and are clinically used. Even though they bind to the same site of AT1R displacing AngII binding but clinical outcomes are significantly different. In this review, we described the clinical significance of each ARB in the treatment of HF and their clinical outcome.

Angiotensin II and leukocyte trafficking: New insights for an old vascular mediator. Role of redox-signaling pathways

Inflammation and activation of the immune system are key molecular and cellular events in the pathogenesis of cardiovascular diseases, including atherosclerosis, hypertension-induced target-organ damage, and abdominal aortic aneurysm. Angiotensin II (Ang-II) is the main effector peptide hormone of the renin-angiotensin system. Beyond its role as a potent vasoconstrictor and regulator of blood pressure and fluid homeostasis, Ang-II is intimately involved in the development of vascular lesions in cardiovascular diseases through the activation of different immune cells. The migration of leukocytes from circulation to the arterial subendothelial space is a crucial immune response in lesion development that is mediated through a sequential and coordinated cascade of leukocyte-endothelial cell adhesive interactions involving an array of cell adhesion molecules present on target leukocytes and endothelial cells and the generation and release of chemoattractants that activate and guide leukocytes to sites of emigration. In this review, we outline the key events of Ang-II participation in the leukocyte recruitment cascade, the underlying mechanisms implicated, and the corresponding redox-signaling pathways. We also address the use of inhibitor drugs targeting the effects of Ang-II in the context of leukocyte infiltration in these cardiovascular pathologies, and examine the clinical data supporting the relevance of blocking Ang-II-induced vascular inflammation.

Platelet CD40 contributes to enhanced monocyte chemoattractant protein 1 levels in patients with resistant hypertension

BACKGROUND

Growing evidence shows that inflammation plays a pivotal role in the pathophysiology of essential hypertension (EH). Although it is acknowledged that target organ damage involves an inflammatory response, most work has focused on the role of macrophages. However, recently, platelets were identified as inducing inflammation partly by releasing cytokines. The goal of our study was to evaluate the role of platelets as inflammatory cells in the pathogenesis of EH.

METHODS

Thirty-nine patients with EH and 30 healthy normotensive controls have been examined. Expression of platelet CD40 was measured by flow cytometry. Serum levels of monocyte chemoattractant protein 1 (MCP-1) and sCD40L were measured via a multiplexing assay. In in vitro experiments, activated platelets were cocultured with human umbilical vein endothelial cells (HUVEC) in the presence and absence of anti-CD154 antibodies. MCP-1 in the supernatants was measured by EIA.

RESULTS

Essential hypertension patients showed significantly enhanced MCP-1 levels with highest levels in EH patients with microalbuminuria. EH patients showed increased expression of platelet CD40. In the cell coculture model, activated platelets were able to significantly induce MCP-1 release from HUVEC in a CD40L-dependent manner. EH patients showed elevated sCD40L levels with a positive correlation with MCP-1 levels.

CONCLUSIONS

Platelets can contribute to enhanced MCP-1 levels in EH. MCP-1 is markedly elevated in serum of EH patients with highest levels in patients with microalbuminuria, one early sign of renal target organ damage. Further studies are required to test whether MCP-1 blocking or antiplatelet strategies may represent new therapeutic options in preventing hypertensive target organ damage.

Angiotensin II type 1 receptor antagonists in animal models of vascular, cardiac, metabolic and renal disease

We have reviewed the effects of angiotensin II type 1 receptor antagonists (ARBs) in various animal models of hypertension, atherosclerosis, cardiac function, hypertrophy and fibrosis, glucose and lipid metabolism, and renal function and morphology. Those of azilsartan and telmisartan have been included comprehensively whereas those of other ARBs have been included systematically but without intention of completeness. ARBs as a class lower blood pressure in established hypertension and prevent hypertension development in all applicable animal models except those with a markedly suppressed renin-angiotensin system; blood pressure lowering even persists for a considerable time after discontinuation of treatment. This translates into a reduced mortality, particularly in models exhibiting marked hypertension. The retrieved data on vascular, cardiac and renal function and morphology as well as on glucose and lipid metabolism are discussed to address three main questions: 1. Can ARB effects on blood vessels, heart, kidney and metabolic function be explained by blood pressure lowering alone or are they additionally directly related to blockade of the renin-angiotensin system? 2. Are they shared by other inhibitors of the renin-angiotensin system, e.g. angiotensin converting enzyme inhibitors? 3. Are some effects specific for one or more compounds within the ARB class? Taken together these data profile ARBs as a drug class with unique properties that have beneficial effects far beyond those on blood pressure reduction and, in some cases distinct from those of angiotensin converting enzyme inhibitors. The clinical relevance of angiotensin receptor-independent effects of some ARBs remains to be determined.

Effects of recombinant adenovirus hepatocyte growth factor gene on myocardial remodeling in spontaneously hypertensive rats

BACKGROUND AND OBJECTIVES

Myocardial hypertrophy and fibrosis are important determinants of congestive heart failure. Previous work has shown that hepatocyte growth factor (HGF) can reduce acute myocardial injury and tissue fibrosis. This study was designed to examine the effects of HGF on myocardial remodeling following sustained hypertension.

METHODS AND RESULTS

There were 4 experimental groups (n = 6) that included spontaneously hypertensive rats (SHRs) injected with 0.1 mL of adenovirus (Ad)-null into the left ventricular (LV) free wall, SHR injected with 0.1 mL of Ad-HGF gene (5 × 10(9) pfu/mL), and SHR injected with 0.1 mL of normal saline, and Wistar Kyoto rats injected with 0.1 mL of Ad-null served as control. At 4 weeks after injection, rats were sacrificed, and HGF expression, myocardial fibrosis, and LV function were determined. We observed that HGF protein expression was reduced in the hearts of SHR (P < .05 vs normal control) and it was markedly increased in SHR injected with Ad-HGF (P < .01 vs SHR injected with Ad-null). Myocardial fibrosis, collagen I, LV mass index (LVMI), and LV end-diastolic pressure (LVEDP) were increased and -dP/dtmax was decreased in SHR injected with Ad-null or normal saline (P < .01 vs normal control). Upregulation of myocardial HGF expression in SHR significantly suppressed myocardial fibrosis, collagen I content, LVMI, LVEDP, and increased -dP/dtmax (all P < .05 vs SHR-Ad-null, n = 6).

CONCLUSIONS

These findings indicate that HGF expression is attenuated in hypertrophic and fibrotic myocardium of SHR. The forced increase in HGF exerts a salutary effect on myocardial fibrosis, collagen I expression, and hemodynamic parameters.

Eprosartan: a review of its use in hypertension

Eprosartan is an angiotensin II receptor antagonist (angiotensin II receptor blocker [ARB]) used in the treatment of hypertension. In large, randomized trials, eprosartan (with or without hydrochlorothiazide [HCTZ]) demonstrated superior antihypertensive efficacy to that of placebo and, when administered at comparable dosage regimens, had similar blood pressure-lowering effects to enalapril. Eprosartan was generally well tolerated in clinical trials and had a lower incidence of persistent dry cough than enalapril. Eprosartan has a neutral effect on metabolic parameters, such as serum lipid levels and glucose homeostasis, and a low propensity for pharmacokinetic drug interactions. The use of eprosartan or other ARBs in combination with HCTZ tends to reverse the potassium loss associated with thiazide diuretics. Independent of its antihypertensive effects, eprosartan was associated with improved clinical outcomes (primary composite endpoint of all causes of mortality and all cardiovascular and cerebrovascular events, including all recurrent events) compared with nitrendipine in a randomized, secondary prevention trial in hypertensive patients with previous cerebrovascular events (MOSES trial). Eprosartan also reduced blood pressure and was associated with a modest improvement in cognitive function in a large observational study in patients > or =50 years of age with newly diagnosed hypertension (OSCAR study). In both of these trials, additional antihypertensive therapy, such as HCTZ, was permitted. Therefore, eprosartan is a useful treatment option in the management of a broad range of patients with hypertension, and its use with HCTZ provides a rational combination regimen.

Hemodynamic and cardiac effects of chronic eprosartan and moxonidine therapy in stroke-prone spontaneously hypertensive rats

The renin-angiotensin and sympathetic nervous systems play critical interlinked roles in the development of left ventricular hypertrophy, fibrosis, and dysfunction. These studies investigated the hemodynamic and cardiac effects of monoblockade and coblockade of renin-angiotensin and sympathetic nervous systems. Stroke-prone spontaneously hypertensive rats (16 weeks old; male; n=12 per group) received the sympatholytic imidazoline compound, moxonidine (2.4 mg/kg per day); the angiotensin-receptor blocker eprosartan (30 mg/kg per day), separately or in combination; or saline vehicle for 8 weeks, SC, via osmotic minipumps. Blood pressure and heart rate were continuously measured by radiotelemetry. After 8 weeks, in vivo cardiac function and structure were measured by transthoracic echocardiography and a Millar conductance catheter, and the rats were then euthanized and blood and heart ventricles collected for various determinations. Compared with vehicle, the subhypotensive dose of moxonidine resulted in lower (P<0.01) heart rate, left ventricular hypertrophy, cardiomyocyte cross-sectional area, interleukin 1 beta, tumor necrosis factor-alpha, and mRNA for natriuretic peptides. Eprosartan reduced pressure (P<0.01), as well as extracellular signal-regulated kinase (ERK) 44 phosphorylation, Bax/Bcl-2, and collagen I/III, and improved left ventricular diastolic function (P<0.03). Combined treatment resulted in greater reductions in blood pressure, heart rate, left ventricular hypertrophy, collagen I/III, and inhibited inducible NO synthase and increased endothelial NO synthase phosphorylation, as well as reduced left ventricular anterior wall thickness, without altering the other parameters. Thus, in advanced hypertension complicated with cardiac fibrosis, sympathetic inhibition and angiotensin II blockade resulted in greater reduction in blood pressure and heart rate, inhibition of inflammation, and improved left ventricular pathology but did not add to the benefits of angiotensin II blockade on cardiac function.

Oxidative stress and left ventricular remodelling after myocardial infarction

In acute myocardial infarction (MI), reactive oxygen species (ROS) are generated in the ischaemic myocardium especially after reperfusion. ROS directly injure the cell membrane and cause cell death. However, ROS also stimulate signal transduction to elaborate inflammatory cytokines, e.g. tumour necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta and -6, in the ischaemic region and surrounding myocardium as a host reaction. Inflammatory cytokines also regulate cell survival and cell death in the chain reaction with ROS. Both ROS and inflammatory cytokines are cardiodepressant mainly due to impairment of intracellular Ca(2+) homeostasis. Inflammatory cytokines stimulate apoptosis through a TNF-alpha receptor/caspase pathway, whereas Ca(2+) overload induced by extensive ROS generation causes necrosis through enhanced permeability of the mitochondrial membrane (mitochondrial permeability transition). Apoptosis signal-regulating kinase-1 (ASK1) is an ROS-sensitive, mitogen-activated protein kinase kinase kinase that is activated by many stress signals and can activate nuclear factor kappaB and other transcription factors. ASK1-deficient mice demonstrate that the ROS/ASK1 pathway is involved in necrotic as well as apoptotic cell death, indicating that ASK1 may be a therapeutic target to reduce left ventricular (LV) remodelling after MI. ROS and inflammatory cytokines activate matrix metalloproteinases which degrade extracellular matrix, causing a slippage of myofibrils and hence LV dilatation. Consequently, collagen deposition is increased and tissue repair is enhanced with myocardial fibrosis and angiogenesis. Since the extent of LV remodelling is a major predictor of prognosis of the patients with MI, the therapeutic approach to attenuating LV remodelling is critically important.

Short-term treatment of stroke-prone spontaneously hypertensive rats with an AT1 receptor blocker protects against hypertensive end-organ damage by prolonged inhibition of the renin-angiotensin system

The aim of the present study was to investigate the effects of short-term treatment with an AT(1) receptor blocker (ARB) on amelioration of hypertensive end-organ damage in stroke-prone spontaneously hypertensive rats (SHRSP). Male SHRSP were divided into two groups: (i) an ARB-treated group; and (ii) a control group. Candesartan (1 mg/kg per day) was administered orally from 6 to 11 weeks of age. At 20 weeks of age, plasma renin activity (PRA), angiotensin II concentrations, angiotensin-converting enzyme (ACE) activity and hydroperoxide content were measured. Expression of intercellular adhesion molecule (ICAM)-1, renin, AT(1) and AT(2) receptors was investigated by reverse transcription-polymerase chain reaction. Blood pressure in the ARB group was slightly lower at 7, 8, 11, 13-15 and 18 weeks of age, but no significant difference in blood pressure was found between the ARB and control groups at 20 weeks of age. All rats in the control group had cerebral oedema, whereas no lesions were found in the ARB group. In the ARB group, PRA, AII and hydroperoxide content were lower than in the control group. In the ARB-treated group, lower ICAM-1 expression was found in the cerebral cortex and slightly, albeit not significantly, lower expression of renin was found in the kidney. In contrast, AT(1) receptor expression in the cerebrum and kidney was higher in the ARB group compared with the control group. These results indicate that short-term treatment of SHRSP with ARB at a young age is effective in preventing cerebral oedema after maturation. Such beneficial effects of ARB may be due, in part, to decreased blood pressure and is likely mainly due to inhibition of total circulating and local renin-angiotensin systems.

Effects of eprosartan on target organ protection

Hypertension is the most important cardiovascular risk factor for stroke. Blood pressure reduction by antihypertensive treatment is clearly efficacious in the prevention of stroke (both primary and secondary), although no clear differences have yet been observed between antihypertensive drug classes. However, a recent study reported the clear superiority of the angiotensin-receptor blocker eprosartan over the calcium channel blocker nitrendipine in cardiovascular protection of hypertensive patients with a previous stroke. Comparative studies using angiotensin-receptor blockers have also suggested the superiority of this class of drugs on primary stroke prevention. This effect may be linked to their beneficial actions on left ventricular hypertrophy, atrial enlargement, and supraventricular arrhythmias, endothelial dysfunction, inflammation, and remodelling, as well as a direct neuroprotective effect mediated through the stimulation of the angiotensin II type-2 receptor. In addition, a sympathoinhibition observed with the renin–angiotensin system blockers and particularly demonstrated with eprosartan, may help to explain the better cardiovascular and cerebrovascular protection in comparison with the calcium antagonist nitrendipine.

Therapeutic effects of angiotensin II type 1 receptor blocker at an advanced stage of hypertensive diastolic heart failure

OBJECTIVE

Angiotensin II type 1 receptor blocker (ARB) is increasingly prescribed for the treatment of systolic heart failure with a growing body of clinical evidence. The roles of ARB, however, remain to be clarified in the treatment of diastolic heart failure (DHF), particularly at its advanced stage. This experimental study investigated the effects of ARB administered at an advanced stage of hypertensive DHF.

METHODS

Dahl salt-sensitive rats fed an 8% NaCl diet from age 7 weeks represent overt DHF at age 20 weeks, as noted in previous studies (hypertensive DHF model). The DHF model rats were randomly divided into two groups at age 17 weeks when left ventricular diastolic dysfunction, hypertrophy, fibrosis, macrophage infiltration and reactive oxygen species generation were already augmented; six rats treated for 3 weeks with a subdepressor dose of ARB (olmesartan 0.6 mg/kg per day), and six untreated rats.

RESULTS

The 3-week administration of ARB significantly decreased the left ventricular end-diastolic pressure in association with attenuation of left ventricular hypertrophy, fibrosis and diastolic dysfunction. Macrophage infiltration was attenuated with decreased gene expression of transforming growth factor-beta1 and monocyte chemoattractant protein-1 in the left ventricular myocardium of the ARB-treated rats. The production of reactive oxygen species also decreased with NADPH oxidase activity.

CONCLUSIONS

ARB provides beneficial effects in hypertensive DHF independent of its antihypertensive effects even if initiated at an advanced stage. The beneficial effects are at least partly attributed to the attenuation of inflammatory changes and oxidative stress through the suppression of cytokine and chemokine production and of NADPH oxidase activity.

Beta3 integrin deficiency promotes cardiac hypertrophy and inflammation

Cardiac hypertrophy commonly develops in response to pressure overload and is associated with increased mortality. Mechanical stress in the heart can result in the activation of transmembrane integrin alphabeta heterodimers that are expressed in cardiomyocytes. Once activated, integrins stimulate focal adhesion kinase, Grb2, c-src, and other signaling molecules to promote cardiomyocyte growth and gene expression. Mechanical stress can also promote cardiac inflammation that may be mediated, in part, by the activation of integrins expressed in blood-borne cells. To address the role of one integrin, beta(3), in the pathogenesis of cardiac hypertrophy, beta(3)(-/-) mice were examined. beta(3)(-/-) Mice developed moderate spontaneous cardiac hypertrophy associated with systolic and diastolic dysfunction, and these abnormalities were exacerbated by transverse aortic constriction. In addition, beta(3)(-/-) mice developed mild cardiac inflammation with infiltrating macrophages at baseline that was markedly worsened by pressure overload. Bone marrow transplantation experiments showed that blood-borne cells were at least partially responsible for the cardiac hypertrophy and inflammation observed in beta(3)(-/-) mice. These results suggest that alpha(v)beta(3) expression in bone marrow has a generalized suppressive effect on cardiac inflammation.

Mechanism of Angiotensin II Type 1 Receptor Blocker Action in the Regression of Left Ventricular Hypertrophy

Left ventricular hypertrophy refers to a pathologic increase in left ventricular mass and is associated with an increased risk of subsequent cardiovascular morbidity and mortality from any cause. In the development of left ventricular hypertrophy there is growth of cardiomyocytes and accumulation of extracellular matrix and fibrosis. The actions are partly induced by angiotensin II, the principal effector of the renin-angiotensin-aldosterone system, binding to the AT1 receptor. Biochemical markers, some implicated in inflammatory changes, correlate with changes in left ventricular mass. The reduction in left ventricular mass brought about with angiotensin-converting enzyme inhibitor or angiotensin receptor blocker (ARB) therapy correlates with a reduction in these inflammatory changes, monitored by brain natriuretic peptide. Recent studies incorporating trials of ARBs have found ARBs to be more effective in reducing left ventricular mass than beta blockers and possibly more effective than calcium antagonists. Initial studies suggest that ARBs and angiotensin-converting enzyme inhibitors may have similar effects in terms of reducing left ventricular hypertrophy, and the combination of angiotensin-converting enzyme inhibitors and ARBs is thought to be synergistic due to a more complete inhibition of the renin-angiotensin-aldosterone system. In conclusion, these agents are efficacious in antihypertensive therapy and can play an important role in the prevention or regression of left ventricular hypertrophy due to hypertension.

Continuous inhibition of the renin-angiotensin system and protection from hypertensive end-organ damage by brief treatment with angiotensin II type 1 receptor blocker in stroke-prone spontaneously hypertensive rats

To investigate the short-term blockade of angiotensin II type 1 (AT1) receptor at the prehypertensive stage and its effects on hypertensive sequelae after maturation, we administered AT1 receptor blocker (ARB, 1 mg/kg/day) to male stroke-prone spontaneously hypertensive rats (SHRSP) from 5 to 10 weeks of age. Although blood pressure in the treated group was significantly lower than in the control group at 10 weeks of age, it gradually increased within 2-3 weeks and reached approximately 250 mm Hg at 17 weeks after cessation of the treatment (27 weeks of age), and reached parity with the control after 20 weeks of age. Nonetheless, hypertensive end-organ damage such as cerebral lesion, cardiac hypertrophy and nephrosclerosis were markedly suppressed in the treated group. Plasma renin activity (PRA), plasma angiotensin II (AII) levels and cerebral angiotensin-converting enzyme (ACE) activity were also significantly lower in the treated group than in the control group, indicating continuous suppression of the circulating and local renin-angiotensin system (RAS). In the brain, intercellular adhesion molecule-1 (ICAM-1) mRNA expression was significantly lower in the cerebral cortex of the treated group than in the control group, while AT1 receptor expression was similar. Such beneficial effects by ARB treatment were not found in the hydralazine-treated group, even though blood pressure changes were similar in both groups. These results demonstrated that early and transient treatment by ARB effective for the prevention of hypertensive end-organ damage. This may be due to the low concentration of plasma angiotensin II by continuous inhibition of RAS even after maturation.

Targets for immunomodulation in cardiovascular disease – where are we now?

The recognition that inflammation plays an important role in most cardiovascular pathologies offers the potential for the development of new therapeutic targets. Heart failure and in-stent restenosis are two areas in which there have been very recent developments in identifying and targeting potential inflammatory mediators. The development of both broad anti-inflammatory strategies and more targeted approaches have confirmed that immunomodulation may have a beneficial effect on disease progression of restenosis and heart failure in experimental animals, while the results from clinical studies highlight the need to consider the inflammatory processes as a whole, rather than some aspects in isolation. This review briefly summarizes the key stimuli for initiating inflammation in cardiovascular disease, recent clinical and experimental developments in the search for appropriate anti-inflammatory strategies and considers the possible pitfalls and future challenges for developing this area.

Leptin does not induce hypertrophy, cell cycle alterations, or production of MCP-1 in cultured rat and mouse cardiomyocytes

BACKGROUND

Leptin has been proposed as an important mediator in cardiovascular pathophysiology. Patients with congestive heart failure (CHF) present high plasma leptin levels. CHF is generally preceded by myocardial remodeling involving hypertrophy, necrosis, and apoptosis.

AIM

To investigate whether leptin causes hypertrophy or cell cycle alterations, or induces MCP-1 synthesis in cardiomyocytes.

METHODS

Primary cultures of neonatal rat cardiomyocytes (PC) and murine cell line HL-1 were used. RT-PCR was used to identify Ob-Rb gene expression. Metabolic activity and proliferation of cardiomyocytes was studied using MTT and BrdU uptake, while apoptosis was assayed with Hoechst dye vital staining and flow cytometry. Measurement of the cell surface area was used to determine hypertrophy. MCP-1 levels were measured by ELISA.

RESULTS

RT-PCR showed Ob-Rb mRNA expression in HL-1 cells. Exposure to leptin induced no changes in metabolic activity, proliferation, and apoptotic rates, and did not alter cell cycle in cardiomyocytes. Leptin did not increase cell size of cardiomyocytes, and MCP-1 synthesis was not detected in PC and HL-1 cells treated with leptin.

CONCLUSION

This work shows that leptin does not induce changes in viability, proliferation, size or apoptosis of rat neonatal and HL-1 cardiomyocytes, and it does not induce MCP-1 secretion in these cells.

Eprosartan

The angiotensin II receptor antagonist eprosartan is approved for the treatment of essential hypertension and may be administered using a convenient once-daily regimen. The drug is a well tolerated and effective antihypertensive agent with benefit in the secondary prevention of cerebrovascular events, independent of blood pressure (BP)-lowering effects. Eprosartan has a low potential for serious adverse events and has not been associated with clinically significant drug interactions, establishing it as a promising agent for combination antihypertensive strategies. Unlike ACE inhibitors such as enalapril, eprosartan does not have a tendency to cause persistent nonproductive cough. Accordingly, eprosartan represents a useful therapeutic option in the management of patients with hypertension, including those who have had a stroke and those with co-morbid type 2 diabetes mellitus.