Role of aldosterone in angiotensin II-induced cardiac and aortic inflammation, fibrosis, and hypertrophy.
ABSTRACT Activation of the renin-angiotensin-aldosterone system is associated with increased extracellular matrix and inflammatory markers in the cardiovascular system. We evaluated the effects of aldosterone antagonism on cardiovascular structure, collagen deposition, and expression of inflammatory markers in 2-week angiotensin (Ang) II-infused rats (120 ng.kg-1.min-1, s.c.)+/-spironolactone or hydralazine (25 mg.kg-1.d-1). Aortic and cardiac collagen density was evaluated with Sirius red staining. NFkappaB and AP-1 were measured by a electrophoretic mobility shift assay, and ED-1 (macrophage marker) and vascular cell adhesion molecule-1 (VCAM-1) were measured by immunohistochemistry. Ang II increased blood pressure (176+/-2 mmHg vs. 115+/-1 mmHg in controls, p<0.01), which was attenuated by spironolactone (147+/-4 mmHg, p<0.01) and prevented by hydralazine (124+/-2 mmHg, p<0.01). Ang II enhanced left ventricular interstitial collagen type I/III deposition (4.1%+/-0.1% vs. 3.1%+/-0.2%, p<0.05), and this was attenuated by spironolactone but not hydralazine. Ang II-induced cardiac perivascular fibrosis was prevented by spironolactone and hydralazine. Ang II significantly increased cardiac AP-1 activity and ED-1 expression, which was prevented by spironolactone only. Ang II-enhanced NFkappaB activity, and VCAM-1 expression was reduced by spironolactone and hydralazine, whereas aortic hypertrophy was prevented by spironolactone and slightly reduced by hydralazine. In conclusion, blockade of mineralocorticoid receptors with spironolactone inhibited Ang II-induced aortic hypertrophy, cardiac transcription factor activation, upregulation of downstream inflammatory markers, and collagen deposition, thus preventing Ang II-induced cardiovascular damage.
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ABSTRACT: Atrial fibrillation (AF), the most common cardiac arrhythmia, is an electrocardiographic description of a condition with multiple and complex underlying mechanisms. Oxidative stress is an important driver of structural remodeling that creates a substrate for AF. Oxidant radicals may promote increase of atrial oxidative damage, electrical and structural remodeling, and atrial inflammation. AF and other cardiovascular morbidities activate angiotensin (Ang-II)-dependent and independent cascades. A key component of the renin-angiotensin-aldosterone system (RAAS) is the mineralocorticoid aldosterone. Recent studies provide evidence of myocardial aldosterone synthesis. Aldosterone promotes cardiac oxidative stress, inflammation and structural/electrical remodeling via multiple mechanisms. In HF patients, aldosterone production is enhanced. In patients and in experimental HF and AF models, aldosterone receptor antagonists have favorable influences on cardiac remodeling and oxidative stress. Therapeutic approaches that seek to reduce AF burden by modulating the aldosterone system are likely beneficial but underutilized.International journal of cardiology 08/2013; · 6.18 Impact Factor
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ABSTRACT: Angiotensin-converting enzyme 2 (ACE2) cleaves angiotensin (Ang) II to generate Ang1-7, which mediates cellular actions through Mas receptors (MasR). Hypertension is accompanied by high or low circulating AngII levels and cardiac/renal injury. The purpose of this study is to explore (i) whether circulating AngII affects ACE2/MasR expressions in the hypertensive heart and kidney; and (ii) whether Ang1-7 regulates cardiac repair/remodeling responses through MasR during hypertension. In the first portion of the study, rats received either an AngII infusion (400ng/kg/min) for 4 weeks, leading to hypertension with high circulating AngII, or an aldosterone (ALDO, 0.75 μg/h) infusion for 4 weeks, leading to hypertension with low/normal circulating AngII. Cardiac and renal ACE2/MasR expressions were examined. We found that cardiac ACE2 was increased and MasR attenuated in both AngII and ALDO groups. However, renal ACE2 and MasR remained unchanged in both AngII- and ALDO-treated animals. In the second portion, rats received AngII infusion with/without MasR antagonist (A779, 1mg/kg/day) for 4 weeks. The roles of MasR blockade in cardiac inflammation, fibrosis, apoptosis, and ventricular function were examined.Chronic AngII infusion caused scattered cardiac injuries, and A779 cotreatment exacerbated cardiac injury, resulting in aggravated inflammatory, fibrogenic, and apoptotic responses compared with the AngII group. Cardiac function, however, was unaltered in the AngII and A779 groups. ACE2 and MasR expressions in the hypertensive heart and kidney are not regulated by circulating AngII levels. Ang1-7 is involved in multiple repair responses, suggesting that therapeutic strategies aimed at administering Ang1-7 hold potential for the management of cardiac remodeling.American Journal of Hypertension 01/2014; · 3.67 Impact Factor
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ABSTRACT: The RAAS through its physiological effectors plays a key role in promoting and maintaining inflammation. Inflammation is an important mechanism in the development and progression of CVD such as hypertension and atherosclerosis. In addition to its main role in regulating blood pressure and its role in hypertension, RAAS has proinflammatory and profibrotic effects at cellular and molecular levels. Blocking RAAS provides beneficial effects for the treatment of cardiovascular and renal diseases. Evidence shows that inhibition of RAAS positively influences vascular remodeling thus improving CVD outcomes. The beneficial vascular effects of RAAS inhibition are likely due to decreasing vascular inflammation, oxidative stress, endothelial dysfunction, and positive effects on regeneration of endothelial progenitor cells. Inflammatory factors such as ICAM-1, VCAM-1, TNFα, IL-6, and CRP have key roles in mediating vascular inflammation and blocking RAAS negatively modulates the levels of these inflammatory molecules. Some of these inflammatory markers are clinically associated with CVD events. More studies are required to establish long-term effects of RAAS inhibition on vascular inflammation, vascular cells regeneration, and CVD clinical outcomes. This review presents important information on RAAS's role on vascular inflammation, vascular cells responses to RAAS, and inhibition of RAAS signaling in the context of vascular inflammation, vascular remodeling, and vascular inflammation-associated CVD. Nevertheless, the review also equates the need to rethink and rediscover new RAAS inhibitors.International journal of inflammation. 01/2014; 2014:689360.