Aldosteronism in heart failure: a proinflammatory/fibrogenic cardiac phenotype. Search for biomarkers and potential drug targets

Galectin-3, N-terminal Propeptides of Type I and III Procollagen in Patients with Atrial Fibrillation and Metabolic Syndrome

The aim of this study was to determine the concentration of galectin-3, PINP and PIIINP in patients with metabolic syndrome (MS) and atrial fibrillation (AF) with an assessment of the relationship with severity of left atrium fibrosis. A total of 480 subjects were included in the case-control study: MS patients (n = 337), 176 of whom had AF, 72 patients with AF without MS and 71 healthy subjects. Galectin-3, PINP and PIIINP blood concentrations and metabolic parameters were compared with the severity of left atrium fibrosis, measured by CARTO3. Galectin-3 in AF and MS patients is higher than in MS without AF and in healthy subjects (10.3 (4.8–15.4), 5.1 (4.3–8.8), 3.2 (2.4–4.2) ng/mL, p < 0.0001). Galectin-3 serum concentration in AF patients with MS is higher than in patients without MS: 10.3 (4.8–15.4), 6.8 (5.2–8.1) ng/mL, p = 0.0001. PINP and PIIINP concentration were higher in patients with AF and MS than in MS without AF: 3499.1 (2299.2–4567.3), 2130.9 (1425.3–2861.8) pg/mL, p < 0.0001, 94.9 (64.8–123.5), 57.6 (40.5–86.9) ng/mL, p < 0.0001. Galectin-3 correlates with PINP (r = 0.496, p < 0.001) and PIIINP concentration (r = 0.451, p < 0.0001). The correlation between galectin-3, PINP and the severity of left atrium fibrosis was found (r = 0.410, p < 0.001; r = 0.623, p < 0.001). Galectin-3 higher than 12.6 ng/mL increased the risk of AF more than five-fold. High galectin-3, PINP and PIIINP concentrations were associated with heart remodeling in MS patients and increased the risk of AF.

Evidence of aldosterone synthesis in human myocardium in acute myocarditis

BACKGROUND

Myocarditis may be self-limited but has been identified as an important contributor to downstream cardiomyopathy. Aldosterone mediates myocardial damage in various conditions, but has not been considered specifically as a therapeutic target for inflammatory damage in acute myocarditis. We sought to demonstrate local aldosterone synthesis in human myocardium affected by acute myocarditis.

METHODS

We evaluated myocardial samples obtained via endomyocardial biopsy (EMB) for expression of CYP11B2, the final and key enzyme for aldosterone synthesis, from patients with acute myocarditis and from stable heart transplant recipients with no evidence of rejection as negative controls. Excised adrenal glands from patients with aldosterone-secreting adenomas were used as positive controls. An experienced cardiovascular pathologist blinded to clinical information rated CYP11B2 stains as negative, positive, or borderline, also recording location of any CYP11B2-positivity.

RESULTS

Sixteen patients' EMB samples showing definite acute myocarditis were identified (50% female). CYP11B2 was positive in 13/16 cases (81%), typically showing diffuse intracardiomyocyte cytoplasmic staining, vs. 2/16 borderline stains in transplant controls (p < 0.001 myocarditis vs. negative controls). All 3 adrenalectomy samples stained positive for CYP11B2 (diffuse intracellular staining). Importantly, no myocarditis or transplant patients were on aldosterone antagonist therapy at the time of biopsy.

CONCLUSIONS

In this proof-of-concept study, myocardium from patients with acute myocarditis demonstrates evidence and high prevalence of local aldosterone synthesis by immunohistochemistry that showed high accuracy, specificity, and sensitivity. Aldosterone warrants consideration as a specific target for therapy in patients with myocardial damage due to inflammation towards strategies that reduce downstream complications.

Galectin-3: a novel biomarker for the prognosis of heart failure

Heart failure (HF) is still a global burden which carries substantial risk of morbidity and mortality. Thus, appropriate approach of diagnosis and layering the prognosis of HF are of great importance. In this paper we discuss and review a novel biomarker, which is called galectin-3 and already approved by Food and Drugs Administration (FDA) as a prediction tool for HF.

Galectin-3, which is secreted by macrophages under the influence of mediators like osteopontin, has been known for its significant role in mediating cardiac fibrosis and inflammation. Numerous studies have shown galectin-3 as a novel prognostic biomarker with high predictive value for cardiovascular mortality and re-hospitalization in HF patients. However, there are also other contradictive studies displayed galectin-3 inferiority against other existed HF prognostic biomarkers like NT-proBNP and ST2. Nevertheless, galectin-3 has some advantages such as more stability and resistance against hemodynamic loading and unloading state, and also it could act as an early indicator of cardiac fibrosis, ventricular remodeling, and renal impairment in HF patients.

Beneficial Cardiovascular Actions of Eplerenone in the Spontaneously Hypertensive Rat

Background: Aldosterone has been implicated as a potential mediator of cardiac and vascular damage in a variety of disorders. This study examined the role of aldosterone and its interplay with the renin-angiotensin system in the pathogenesis of hypertension. To this end, the effects of the aldosterone antagonist eplerenone and the angiotensin converting enzyme inhibitor lisinopril on cardiovascular mass, myocardial collagen, and coronary circulation were examined in spontaneously hypertensive rats.

Methods: Male, 22-week-old rats were randomly divided into 4 groups (12 in each). The control group received no treatment, the second group was given eplerenone (100 mg/kg/day), the third received lisinopril (3 mg/kg/day), and the fourth was given eplerenone and lisinopril. After 12 weeks of respective treatments, systemic and regional hemodynamics and cardiovascular mass indexes were measured in conscious instrumented rats.

Results: Eplerenone decreased arterial pressure but did not affect left ventricular mass or hydroxyproline concentration (an estimate of collagen). It did, however, reduce minimal coronary vascular resistance and increased coronary flow reserve. Lisinopril decreased arterial pressure and ventricular mass but did not affect regional hemodynamics. The combination therapy produced synergistic effects.

Conclusion: Aldosterone antagonism improved coronary and systemic hemodynamics in adult spontaneously hypertensive rats but did not affect cardiovascular mass indexes. The finding that lisinopril and eplerenone decreased arterial pressure to the same extent but had different cardiovascular effects suggested that these effects might be pressure independent.

The relation among aldosterone, galectin-3, and myocardial fibrosis: a prospective clinical pilot follow-up study

Primary aldosteronism has been associated with myocardial fibrosis, and is the most common cause of secondary hypertension. We previously showed that aldosterone can induce the secretion of galectin-3. The aim of this study was to investigate the association between myocardial fibrosis and plasma galectin-3 level in patients with primary aldosteronism. We prospectively analyzed 11 patients with aldosterone-producing adenoma (APA) who received adrenalectomy from December 2006 to October 2008, and 17 patients with essential hypertension as controls. Levels of plasma galectin-3 were determined in both groups, and both groups underwent echocardiography with cyclic variations of integrated backscatter (CVIBS) to characterize tissue initially and 1 year after surgery in the APA group. Diastolic blood pressure, concentration of plasma aldosterone and aldosterone-renin ratio were significantly higher, and serum potassium level and plasma renin activity significantly lower in the APA group compared to the controls. In addition, left ventricular mass index was significantly higher and CVIBS significantly lower in the APA group (7.3±2.0 vs 9.2±1.7 dB, p=0.015). Furthermore, the concentration of plasma galectin-3 was significantly higher in the APA group (2.1±0.9 vs 1.1±0.6 ng/mL, p=0.005) compared to the controls. CVIBS was correlated to plasma galectin-3 level. In the APA group, CVIBS increased significantly (7.3±2.0 to 9.2±2.4 dB, p=0.032) and plasma galectin-3 decreased (2.1±0.9 to 1.2±0.6, p=0.049) 1 year postadrenalectomy. The patients with APA had increased myocardial fibrosis, and this was associated with a higher plasma galectin-3 level. Both increased myocardial fibrosis and plasma galectin-3 level recovered at least partially after adrenalectomy.

TRIAL REGISTRATION NUMBER

200611031R; Results.

Galectin-3: A Link between Myocardial and Arterial Stiffening in Patients with Acute Decompensated Heart Failure?

BACKGROUND

Heart failure is accompanied by abnormalities in ventricular-vascular interaction due to increased myocardial and arterial stiffness. Galectin-3 is a recently discovered biomarker that plays an important role in myocardial and vascular fibrosis and heart failure progression.

OBJECTIVES

The aim of this study was to determine whether galectin-3 is correlated with arterial stiffening markers and impaired ventricular-arterial coupling in decompensated heart failure patients.

METHODS

A total of 79 inpatients with acute decompensated heart failure were evaluated. Serum galectin-3 was determined at baseline, and during admission, transthoracic echocardiography and measurements of vascular indices by Doppler ultrasonography were performed.

RESULTS

Elevated pulse wave velocity and low arterial carotid distensibility are associated with heart failure in patients with preserved ejection fraction (p = 0.04, p = 0.009). Pulse wave velocity, carotid distensibility and Young's modulus did not correlate with serum galectin-3 levels. Conversely, raised galectin-3 levels correlated with an increased ventricular-arterial coupling ratio (Ea/Elv) p = 0.047, OR = 1.9, 95% CI (1.0‑3.6). Increased galectin-3 levels were associated with lower rates of left ventricular pressure rise in early systole (dp/dt) (p=0.018) and raised pulmonary artery pressure (p = 0.046). High galectin-3 levels (p = 0.038, HR = 3.07) and arterial pulmonary pressure (p = 0.007, HR = 1.06) were found to be independent risk factors for all-cause mortality and readmissions.

CONCLUSIONS

This study showed no significant correlation between serum galectin-3 levels and arterial stiffening markers. Instead, high galectin-3 levels predicted impaired ventricular-arterial coupling. Galectin-3 may be predictive of raised pulmonary artery pressures. Elevated galectin-3 levels correlate with severe systolic dysfunction and together with pulmonary hypertension are independent markers of outcome.

Inhibition of aldosterone synthase (CYP11B2) by torasemide prevents atrial fibrosis and atrial fibrillation in mice

Loop diuretics are used for fluid control in patients with heart failure. Furosemide and torasemide may exert differential effects on myocardial fibrosis. Here, we studied the effects of torasemide and furosemide on atrial fibrosis and remodeling during atrial fibrillation. In primary neonatal cardiac fibroblasts, torasemide (50μM, 24h) but not furosemide (50μM, 24h) reduced the expression of connective tissue growth factor (CTGF; 65±6%) and the pro-fibrotic miR-21 (44±23%), as well as the expression of lysyl oxidase (LOX; 57±8%), a regulator of collagen crosslinking. Mineralocorticoid receptor (MR) expression and activity were not altered. Torasemide but not furosemide inhibited human aldosterone synthase (CYP11B2) activity in transfected lung fibroblasts (V79MZ cells) by 75±1.8%. The selective CYP11B2 inhibitor SL242 mimicked the torasemide effects. Mice with cardiac overexpression of Rac1 GTPase (RacET), which develop atrial fibrosis and spontaneous AF with aging, were treated long-term (8months) with torasemide (10mg/kg/day), furosemide (40mg/kg/day) or vehicle. Treatment with torasemide but not furosemide prevented atrial fibrosis in RacET as well as the up-regulation of CTGF, LOX, and miR-2, whereas MR expression and activity remained unaffected. These effects correlated with a reduced prevalence of atrial fibrillation (33% RacET+Tora vs. 80% RacET). Torasemide but not furosemide inhibits CYP11B2 activity and reduces the expression of CTGF, LOX, and miR-21. These effects are associated with prevention of atrial fibrosis and a reduced prevalence of atrial fibrillation in mice.

The Association between Glomerular Hyperfiltration and Left Ventricular Structure and Function in Patients with Primary Aldosteronism

BACKGROUND

Glomerular hyperfiltration has been recently noticed as an important issue in primary aldosteronism (PA) patients. However, its effect on the cardiovascular system remains unknown.

METHODS

We prospectively analyzed 47 PA patients including 11 PA patients with estimated glomerular filtration rate (eGFR) > 130 ml/min per 1.73 m2 (group 1), and 36 PA patients with eGFR 90-110 ml/min per 1.73 m2 (group 2). Fourteen essential hypertension (EH) patients with eGFR 90-110 ml/min per 1.73 m2 were included as the control group (group 3). Echocardiography including left ventricular mass index (LVMI) measurement and tissue Doppler imaging (TDI) was performed. Predicted left ventricular mass (LVM) was calculated. Inappropriate LVM was defined as an excess of > 35% from the predicted value.

RESULTS

The value of LVMI decreased significantly in order from groups 1 to 3 (group 1>2>3). While group 2 had a significantly higher percentage of inappropriate LVM than group 3, the percentage of inappropriate LVM were comparable in groups 1 and 2. Group 1 had a higher mitral E velocity, E/A ratio than that of group 2. In the TDI study, the E/E' ratio also decreased significantly in order from groups 1 to 3 (group 1>2>3). Group 2 had lower E' than that of group 3, although the E' of group 1 and 2 were comparable.

CONCLUSIONS

Although PA patients with glomerular hyperfiltration were associated with higher LVMI, higher mitral E velocity, higher E/E' ratio, they had comparable E' with PA patients with normal GFR. This phenomenon may be explained by higher intravascular volume in this patient group.

Aldosterone induced galectin-3 secretion in vitro and in vivo: from cells to humans

Context

Patients with primary aldosteronism are associated with increased myocardial fibrosis. Galectin-3 is one of the most important mediators between macrophage activation and myocardial fibrosis.

Objective

To investigate whether aldosterone induces galectin-3 secretion in vitro and in vivo.

Methods and Results

We investigated the possible molecular mechanism of aldosterone-induced galectin-3 secretion in macrophage cell lines (THP-1 and RAW 264.7 cells). Aldosterone induced galectin-3 secretion through mineralocorticoid receptors via the PI3K/Akt and NF-κB transcription signaling pathways. In addition, aldosterone-induced galectin-3 expression enhanced fibrosis-related factor expression in fibroblasts. We observed that galectin-3 mRNA from peripheral blood mononuclear cells and serum galectin-3 levels were both significantly increased in mice implanted with aldosterone pellets on days 7 and 14. We then conducted a prospective preliminary clinical study to investigate the association between aldosterone and galectin-3. Patients with aldosterone-producing adenoma had a significantly higher plasma galectin-3 level than patients with essential hypertension. One year after adrenalectomy, the plasma galectin-3 level had decreased significantly in the patients with aldosterone-producing adenoma.

Conclusion

This study demonstrated that aldosterone could induce galectin-3 secretion in vitro and in vivo.

Using galectin-3 to reduce heart failure rehospitalization

ABSTRACT: 

Increasing attention is being paid towards reducing short-term heart failure readmissions in recent years. Biomarkers such as galectin-3 are likely to play pivotal roles in future heart failure management strategies as they can provide objective information on various pathophysiologic processes involved in heart failure. Galectin-3 is a biomarker of inflammation and fibrosis, which is strongly associated with adverse remodeling of the myocardium and subsequent left ventricular dysfunction. Clinically, elevated galectin-3 levels are associated with increased risk for short- and long-term risk for mortality and heart failure readmission. Galectin-3 can provide incremental predictive value for adverse events over natriuretic peptides. Although significant work is still required to further define the role of galectin-3, it has the potential to become an important part of future heart failure management algorithms by helping to provide an individualized risk profile, which can be used to optimize resource allocation and improve treatment outcomes.

Comparison the prognostic value of galectin-3 and serum markers of cardiac extracellular matrix turnover in patients with chronic systolic heart failure

BACKGROUND

Galectin-3 (Gal-3) shows the ability of survival prediction in heart failure (HF) patients. However, Gal-3 is strongly associated with serum markers of cardiac extracellular matrix (ECM) turnover. The aim of this study is to compare the impact of Gal-3 and serum markers of cardiac ECM turnover on prognostic prediction of chronic systolic HF patients.

METHODS

Serum Gal-3, brain natriuretic peptide (BNP), extracellular matrix including type I and III aminoterminal propeptide of procollagen (PINP and PIIINP), matrix metalloproteinase-2, 9 (MMP-2, 9), and tissue inhibitor of metalloproteinase-1 (TIMP-1) were analyzed. Cox regression analysis was used for survival analysis.

RESULTS

A total of 105 (81 male) patients were enrolled. During 980±346 days follow-up, 17 patients died and 36 episodes of HF admission happened. Mortality of these patients was significantly associated with the log PIIINP (β= 15.380; P=0.042), log TIMP-1(β= 44.530; P=0.003), log MMP-2 (β= 554.336; P<0.001), log BNP (β= 28.273; P=0.034). Log Gal-3 (β= 7.484; P=0.066) is borderline associated with mortality. Mortality or first HF admission of these patients was significantly associated with the log TIMP-1(β= 16.496; P=0.006), log MMP-2 (β= 221.864; P<0.001), log BNP (β= 5.999; P=0.034). Log Gal-3 (β= 4.486; P=0.095) only showed borderline significance. In several models adjusting clinical parameters, log MMP-2 was significantly associated with clinical outcome. In contrast, log Gal-3 was not.

CONCLUSION

The prognostic strength of MMP-2 to clinical outcome prediction in HF patients is stronger than Gal-3.

Impact of aldosterone antagonists on the substrate for atrial fibrillation: aldosterone promotes oxidative stress and atrial structural/electrical remodeling

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.

Aldosterone, mineralocorticoid receptor, and heart failure

Several large clinical studies have demonstrated the important benefit of mineralocorticoid receptor (MR) antagonists in patients with heart failure, left ventricular dysfunction after myocardial infarction, hypertension or diabetic nephropathy. Aldosterone adjusts the hydro-mineral balance in the body, and thus participates decisively to the control of blood pressure. This traditional view of the action of aldosterone restricted to sodium reabsorption in epithelial tissues must be revisited. Clinical and experimental studies indicated that chronic activation of the MR in target tissues induces structural and functional changes in the heart, kidneys and blood vessels. These deleterious effects include cardiac and renal fibrosis, inflammation and vascular remodeling. It is important to underscore that these effects are due to elevated MR activation that is inadequate for the body salt requirements. Aldosterone is generally considered as the main ligand of MR. However, this is a matter of debate especially in heart. Complexity arises from the glucocorticoids with circulating concentrations much higher than those of aldosterone, and the fact that the MR has a high affinity for 11β-hydroxyglucocorticoids. Nevertheless, the beneficial effects of MR inhibition in patients with heart failure emphasize the importance of this receptor in cardiovascular tissue. Diverse experimental models and strains of transgenic mice have allowed to dissect the effects of aldosterone and the MR in the heart. Taken together experimental and clinical data clearly highlight the deleterious cardiovascular effects of MR stimulation.

Aldosterone, mortality, and acute ischaemic events in coronary artery disease patients outside the setting of acute myocardial infarction or heart failure

BACKGROUND

Recent studies have demonstrated that aldosterone levels measured in patients with heart failure or acute myocardial infarction (MI) are associated with long-term mortality, but the association with aldosterone levels in patients with coronary artery disease (CAD) outside these specific settings remains unknown. In addition, no clear mechanism has been elucidated to explain these observations. The present study was designed to evaluate the relationship between the level of aldosterone and the risk of death and acute ischaemic events in CAD patients with a preserved left ventricular (LV) function and no acute MI.

METHODS AND RESULTS

In 799 consecutive CAD patients referred for elective coronary angioplasty measurements were obtained before the procedure for: aldosterone (median = 25 pg/mL), brain natriuretic peptide (BNP) (median = 35 pg/mL), hsC-reactive protein (median = 4.17 mg/L), and left ventricular ejection fraction (mean = 58%). Patients with acute MI or coronary syndrome (ACS) who required urgent revascularization were not included in the study. The primary endpoint, cardiovascular death, occurred in 41 patients during a median follow-up period of 14.9 months. Secondary endpoints-total mortality, acute ischaemic events (acute MI or ischaemic stroke), and the composite of death and acute ischaemic events-were observed in 52, 54, and 94 patients, respectively. Plasma aldosterone was found to be related to BMI, hypertension and NYHA class, and inversely related to age, creatinine clearance, and use of beta-blockers. Multivariate Cox model analysis demonstrated that aldosterone was independently associated with cardiovascular mortality (P = 0.001), total mortality (P = 0.001), acute ischaemic events (P = 0.01), and the composite of death and acute ischaemic events (P = 0.004). Reclassification analysis, using integrated discrimination improvement (IDI) and net reclassification improvement (NRI), demonstrated incremental predictive value of aldosterone (P < 0.0001).

CONCLUSION

Our results demonstrate that, in patients with CAD but without heart failure or acute MI, the level of aldosterone is strongly and independently associated with mortality and the occurrence of acute ischaemic events.

Depression in heart failure: biobehavioral mechanisms

The etiology, predictive value, and biobehavioral aspects of depression in heart failure (HF) are described in this article. Clinically elevated levels of depressive symptoms are present in approximately 1 out of 5 patients with HF. Depression is associated with poor quality of life and a greater than 2-fold risk of clinical HF progression and mortality. The biobehavioral mechanisms accounting for these adverse outcomes include biological processes (elevated neurohormones, autonomic nervous system dysregulation, and inflammation) and adverse health behaviors (physical inactivity, medication nonadherence, poor dietary control, and smoking). Depression often remains undetected because of its partial overlap with HF-related symptoms and lack of systematic screening. Behavioral and pharmacologic antidepressive interventions commonly result in statistically significant but clinically modest improvements in depression and quality of life in HF, but not consistently better clinical HF or cardiovascular disease outcomes. Documentation of the biobehavioral pathways by which depression affects HF progression will be important to identify potential targets for novel integrative behavioral and pharmacologic interventions.

Regulation of circulating progenitor cells in left ventricular dysfunction

BACKGROUND

Reductions in numbers of circulating progenitor cells (CD34+ cell subsets) have been demonstrated in patients at risk for, or in the presence of, cardiovascular disease. The mediators of these reductions remain undefined. To determine whether neurohumoral factors might regulate circulating CD34+ cell subsets in vivo, we studied complementary canine models of left ventricular (LV) dysfunction.

METHODS AND RESULTS

A pacing model of severe LV dysfunction and a hypertensive renal wrap model in which dogs were randomized to receive deoxycorticosterone acetate (DOCA) were studied. Circulating CD34+ cell subsets including hematopoietic precursor cells (HPCs: CD34+/CD45(dim)/VEGFR2-) and endothelial progenitor cells (EPCs: CD34+/CD45-/VEGFR2+) were quantified. Additionally, the effect of mineralocorticoid excess on circulating progenitor cells in normal dogs was studied. The majority of circulating CD34+ cells expressed CD45dimly and did not express VEGFR2, consistent with an HPC phenotype. HPCs were decreased in response to pacing, and this decrease correlated with plasma aldosterone levels (Spearman rank correlation=-0.67, P=0.03). In the hypertensive renal wrap model, administration of DOCA resulted in decreased HPCs. No changes were seen in EPCs in either model. Normal dogs treated with DOCA exhibited a decrease in HPCs in peripheral blood but not bone marrow associated with decreased telomerase activity.

CONCLUSIONS

This is the first study to demonstrate that mineralocorticoid excess, either endogenous or exogenous, results in reduction in HPCs. These data suggest that mineralocorticoids may induce accelerated senescence of progenitor cells, leading to their reduced survival and decline in numbers.

Aldosterone and long-term outcome after myocardial infarction: A substudy of the french nationwide Observatoire sur la Prise en charge hospitalière, l'Evolution à un an et les caRactéristiques de patients présentant un infArctus du myocarde avec ou sans onde Q (OPERA) study

BACKGROUND

High plasma aldosterone levels at presentation are correlated to poor outcome after ST elevation acute myocardial infarction (AMI). Whether there is a relationship between aldosterone levels and outcome in a broader spectrum of patients admitted for AMI defined by the new definition based on troponin levels remains unknown.

METHODS

Plasma aldosterone, C-reactive protein, and brain natriuretic peptide (BNP) were measured in 471 patients, 24 and 72 hours after admission for AMI defined by the new definition. The primary outcome was the composite of death, resuscitated cardiac arrest, recurrent/extended myocardial infarction, recurrent ischemia, heart failure, and stroke.

RESULTS

The highest aldosterone levels quartile at 24 hours was significantly associated with the occurrence of the primary outcome (P < .0001), death (P < .05), heart failure (P < .05), ventricular (P < .0001) and supraventricular arrhythmias (P < .05), and acute renal failure (P < .01) during the in-hospital period, and higher rates of mortality (P < .05) at 1-year follow-up. Independent correlates of the primary outcome at 1 year were age > or =73 (odds ratio [OR] 2.22 [1.38-3.57]), heart failure (OR 6.46 [1.99-20.98]), 24-hour aldosterone > or =103.6 pg.mL(-1) (OR 1.72 [1.07-2.77]), and BNP > or =389 pg.mL(-1) (OR 2.35 [1.44-3.84]) concentrations. The model applied to the 72-hour variables, identified the same correlates.

CONCLUSIONS

Using the new definition of AMI, based on troponin levels, regardless of ST-segment elevation and management strategies, high aldosterone concentration is associated with major adverse in-hospital events and is an independent correlate of clinical outcome at 1 year. These findings warrant trials assessing the benefit of early aldosterone blockade in such patients.

Macrophage Depletion in Hypertensive Rats Accelerates Development of Cardiomyopathy

Inflammation contributes to the process of ventricular remodeling after acute myocardial injury. To investigate the role of macrophages in the chronic process of cardiac remodeling, they were selectively depleted by intravenous administration of liposomal clodronate in heart failure—prone hypertensive Ren-2 rats from the age of 7 until 13 weeks. Plain liposomes were used for comparison. Liposomal clodronate treatment reduced the number of blood monocytes and decreased the number of macrophages in the myocardium. Compared to plain liposomes, liposomal clodronate treatment rapidly worsened left ventricular ejection function in hypertensive rats. Liposomal clodronate— treated Ren-2 rat hearts showed areas of myocyte loss with abundant inflammatory cell infiltration, predominantly comprising CD4 positive T lymphocytes. The current study showed that lack of macrophages was associated with earlier development of myocardial dysfunction in hypertensive rats. Modulation of macrophage function may be of value in the evolution of cardiomyopathy.

Aldosterone activates endothelial exocytosis

Although elevated levels of aldosterone are associated with vascular inflammation, the proinflammatory pathways of aldosterone are not completely defined. We now show that aldosterone triggers endothelial cell exocytosis, the first step in leukocyte trafficking. Exogenous aldosterone stimulates endothelial exocytosis of Weibel-Palade bodies, externalizing P-selectin and releasing von Willebrand factor. Spironolactone, a nonselective mineralocorticoid receptor (MR) blocker, antagonizes aldosterone-induced endothelial exocytosis. Knockdown of the MR also decreases exocytosis, suggesting that the MR mediates exocytosis. Aldosterone triggers exocytosis within minutes, and this effect is not inhibited by actinomycin D, suggesting a nongenomic effect of aldosterone. Aldosterone treatment of endothelial cells increases leukocyte adherence to endothelial cells in culture. Taken together, our data suggest that aldosterone activates vascular inflammation in part through nongenomic, MR-mediated pathways. Aldosterone antagonism may decrease vascular inflammation and cardiac fibrosis in part by blocking endothelial exocytosis.

Microvascular transport model predicts oxygenation changes in the infarcted heart after treatment

Chronic heart failure is most commonly due to ischemic cardiomyopathy after a previous myocardial infarction (MI). Rebuilding lost myocardium to prevent heart failure mandates a neovasculature able to nourish new cardiomyocytes. Previously we have used a series of novel techniques to directly measure the ability of the scar neovasculature to deliver and exchange oxygen at 1–4 wk after MI in rats following left coronary artery ligation. In this study, we have developed a morphologically realistic mathematical model of oxygen transport in cardiac tissue to help in deciding what angiogenic strategies should be used to rebuild the vasculature. The model utilizes microvascular morphology of cardiac tissue based on available morphometric images and is used to simulate experimentally measured oxygen levels after MI. Model simulations of relative oxygenation match experimental measurements closely and can be used to simulate distributions of oxygen concentration in normal and infarcted rat hearts. Our findings indicate that both vascular density and vascular spatial distribution play important roles in cardiac tissue oxygenation after MI. Furthermore, the model can simulate relative changes in tissue oxygen levels in infarcted tissue treated with proangiogenic compounds such as losartan. From the minimum oxygen concentration myocytes need to maintain their normal function, we estimate that 2 wk after MI 29% of the myocardium is severely hypoxic and that the vascular density of the infarcted tissue should reach 75% of normal tissue to ensure that no areas of the myocardium are critically hypoxic.

Targeted delivery of antibody conjugated liposomal drug carriers to rat myocardial infarction

Immunoliposome (IL) targeting to areas of inflammation after an acute myocardial infarction (MI) could provide the means by which pro-angiogenic compounds can be selectively targeted to the infarcted region. The adhesion of model drug carriers and ILs coated with an antibody to P-selectin was quantified in a rat model of MI following left coronary artery ligation. Anti-P-selectin coated model drug carriers showed a 140% and 180% increase in adhesion in the border zone of the MI 1 and 4 h post-MI, respectively. Radiolabeled anti-P-selectin ILs injected immediately post-MI and allowed to circulate 24 h showed an 83% increase in targeting to infarcted myocardium when compared to adjacent non-infarcted myocardium. Radiolabeled anti-P-selectin ILs injected 4 h post-MI and allowed to circulate for 24 h showed a 92% increase in accumulation in infarcted myocardium when compared to adjacent non-infarcted myocardium. Targeting to upregulated adhesion molecules on the endothelium provides a promising strategy for selectively delivering compounds to the infarct region of the myocardium using our liposomal-based drug delivery vehicle.

Long-term mineralocorticoid receptor blockade reduces fibrosis and improves cardiac performance and coronary hemodynamics in elderly SHR

Aldosterone has been implicated as one of the mediators of cardiovascular injury in various diseases. This study examines whether mineralocorticoid antagonism ameliorates or prevents the adverse cardiac effects of hypertension and aging. Male 22-wk-old spontaneously hypertensive rats (SHR) were divided into two groups, 15 rats in each. One group received no treatment; the other was given eplerenone (∼100 mg·kg−1·day−1). At the age of 54 wk, indexes of cardiovascular mass, systemic and regional hemodynamics, including coronary, left ventricular function, and myocardial collagen content, were determined in all rats. Hemodynamic studies were done in conscious rats. Arterial pressure was lowered only slightly in eplerenone-treated rats, and cardiac output and total peripheral resistance did not differ from control rats. Left and right ventricular and aortic mass indexes were unaffected by eplerenone; however, concentration of hydroxyproline in the right and left ventricle was decreased significantly ( P < 0.05) by eplerenone. This was accompanied by an improvement in left ventricular diastolic function and coronary hemodynamics. In conclusion, long-term therapy with the mineralocorticoid receptor antagonist eplerenone ameliorated adverse cardiac effects of both hypertension and aging in SHR. Thus reduction in myocardial fibrosis, paralleled by improvements in left ventricular function and coronary hemodynamics, was observed in eplerenone-treated SHR.

Mechanisms of target organ damage caused by hypertension: therapeutic potential

Hypertension is a major risk factor for cardiovascular mortality and morbidity through its effects on target organs like the brain, heart, and kidney. Structural alterations in the microcirculation form a major link between hypertension and target organ damage. In this review, we describe damages related to hypertension in these target organs and the mechanisms involved in the pathogenesis of hypertension-induced cardiovascular diseases such as dementia, cardiac ischemia and remodeling, or nephropathy. We also focus on the therapeutical potential on the basis of such mechanisms. Several antihypertensive agents like diuretics, angiotensin converting enzyme (ACE) inhibitors, angiotensin II (Ang II) receptor antagonists, beta-blockers, or calcium channel blockers (CCBs) have been shown to reduce effectively hypertension associated cardiovascular events and to improve end organ damage. More recently, aldosterone antagonism has also shown beneficial effects. Part of the favorable effects of these agents is due to blood pressure lowering as such. Other mechanisms such as oxidative stress, inflammation, or endothelial dysfunction have appeared to play a key role in the pathogenesis of target organ damage and therefore represent another important pathway for therapy. In this review, we discuss the different therapeutic approaches aiming at reducing cardiovascular events and damages induced by hypertension.

Ligand-specific glucocorticoid receptor activation in human platelets

Few studies have addressed the effects of classical anti-inflammatory glucocorticoids on platelet function. Here, we report for the first time that human platelets contain the glucocorticoid receptor (GR) as identified by a combination of biochemical and functional techniques. Ligand-binding studies revealed the presence of a high- and low-affinity binding site for [3H]-dexamethasone in platelets. The 2 GR ligands prednisolone and dexamethasone competed for [3H]-dexamethasone binding, as did the mineralocorticoid aldosterone. However, while prednisolone (1-10 microM) reduced adenosine diphosphate (ADP, 4 microM) and thromboxane A2 receptor agonist U46619 induced platelet aggregation (up to 75%), dexamethasone had no effect. The inhibition produced by prednisolone was reversed by preincubation with the GR antagonist mifepristone (10 microM; RU486), suggesting the functional importance of the ligand-receptor complex. In addition, prednisolone caused a marked (approximately 50%) reduction in thromboxane B2 levels, whereas dexamethasone was without effect. The apparently anomalous binding data were clarified by the fact that washed platelets (1) contained mineralocorticoid receptor and that (2) it was associated with GR. Taken together, our data suggest that platelet GR forms a heterodimeric complex with the mineralocorticoid receptor that is susceptible to differential activation by specific receptor ligands.

The scar neovasculature after myocardial infarction in rats

A series of novel techniques, adapted from the field of tumor biology, were developed to quantify vascular structure and function and to explore the role of ANG II receptor AT1 in cardiac remodeling after myocardial infarction (MI). We examined the scar neovasculature at 1-4 wk post-MI in Sprague-Dawley rats with a view toward its ability to deliver and exchange oxygen. CD31 and DiOC7(3) staining was used to visualize anatomical vessels vs. those perfused. EF5/Cy3 immunohistochemical staining was used to quantify tissue hypoxia. We compared untreated controls with rats treated with losartan, an AT1 receptor antagonist. Our findings indicated that, at the infarct site, there was not only a 42-75% (1-4 wk post-MI) decrease in the number of anatomical vessels compared with controls but also a decrease in the fraction of perfused vessels from 70% in normal coronary vasculature to 48% at the infarct site. These changes were accompanied by progressive increases in diffusion distance and tissue hypoxia (100% increase in EF5/Cy3 staining at 4 wk post-MI). Losartan-treated rats exhibited a significantly less marked reduction in vascular perfusion and a significantly lesser extent of tissue hypoxia. Over the course of 4 wk post-MI, there is a reduction in coronary vasculature at the infarct site, the extent of which is attenuated by losartan. These findings implicate AT1 receptor upregulation, and perhaps angiotensin-related peptides, as being antiangiogenic.

Galectin-3 marks activated macrophages in failure-prone hypertrophied hearts and contributes to cardiac dysfunction

BACKGROUND

Inflammatory mechanisms have been proposed to be important in heart failure (HF), and cytokines have been implicated to add to the progression of HF. However, it is unclear whether such mechanisms are already activated when hypertrophied hearts still appear well-compensated and whether such early mechanisms contribute to the development of HF.

METHODS AND RESULTS

In a comprehensive microarray study, galectin-3 emerged as the most robustly overexpressed gene in failing versus functionally compensated hearts from homozygous transgenic TGRmRen2-27 (Ren-2) rats. Myocardial biopsies obtained at an early stage of hypertrophy before apparent HF showed that expression of galectin-3 was increased specifically in the rats that later rapidly developed HF. Galectin-3 colocalized with activated myocardial macrophages. We found galectin-3-binding sites in rat cardiac fibroblasts and the extracellular matrix. Recombinant galectin-3 induced cardiac fibroblast proliferation, collagen production, and cyclin D1 expression. A 4-week continuous infusion of low-dose galectin-3 into the pericardial sac of healthy Sprague-Dawley rats led to left ventricular dysfunction, with a 3-fold differential increase of collagen I over collagen III. Myocardial galectin-3 expression was increased in aortic stenosis patients with depressed ejection fraction.

CONCLUSIONS

This study shows that an early increase in galectin-3 expression identifies failure-prone hypertrophied hearts. Galectin-3, a macrophage-derived mediator, induces cardiac fibroblast proliferation, collagen deposition, and ventricular dysfunction. This implies that HF therapy aimed at inflammatory responses may need to be targeted at the early stages of HF and probably needs to antagonize multiple inflammatory mediators, including galectin-3.

Effects of loop diuretics on myocardial fibrosis and collagen type I turnover in chronic heart failure

OBJECTIVES

This individually randomized, open-label, parallel-group pilot study was designed to test the hypothesis that the ability of loop diuretics to interfere with cardiac fibrosis in chronic heart failure (CHF) may be different between compounds.

BACKGROUND

The apparent mortality and cardiac benefits seen in studies comparing torasemide with furosemide in CHF suggest that torasemide may have beneficial effects beyond diuresis (e.g., on the process of cardiac fibrosis).

METHODS

Patients with New York Heart Association functional class II to IV CHF received diuretic therapy with either 10 to 20 mg/day oral torasemide (n = 19) or 20 to 40 mg/day oral furosemide (n = 17), in addition to their existing standard CHF therapy for eight months. At baseline and after eight months, right septal endomyocardial biopsies were obtained to quantify collagen volume fraction (CVF) with an automated image analysis system. Serum carboxy-terminal peptide of procollagen type I (PIP) and serum carboxy-terminal telopeptide of collagen type I (CITP), indexes of collagen type I synthesis and degradation, respectively, were measured by specific radioimmunoassays.

RESULTS

In torasemide-treated patients, CVF decreased from 7.96 +/- 0.54% to 4.48 +/- 0.26% (p < 0.01), and PIP decreased from 143 +/- 7 to 111 +/- 3 microg/l (p < 0.01). Neither CVF nor PIP changed significantly in furosemide-treated patients. In all patients, CVF was directly correlated with PIP (r = 0.88, p < 0.001) before and after treatment. No changes in CITP were observed with treatment in either group.

CONCLUSIONS

These findings suggest that loop diuretics possess different abilities to reverse myocardial fibrosis and reduce collagen type I synthesis in patients with CHF.