Aldosteronism and peripheral blood mononuclear cell activation: a neuroendocrine-immune interface

Diagnostic accuracy of using multiple cytokines to predict aldosterone-producing adenoma

Here, we aimed to study the important cytokines in plasma to identify the aldosterone-producing adenoma (APA). 19 unilateral primary aldosteronism (UPA) patients and 19 healthy people were divided into UPA group and Control group, and the serum of bilateral adrenal veins and inferior vena cava collected by adrenal blood sampling (AVS) in UPA patients and the serum from the healthy subjects were all used to detect multiple cytokines by Luminex immunoassays. Additionally, The UPA patients subjected to laparoscopic adrenalectomy were divided into different groups by pathological results for further study. According our results, IP-10, CXCL9 and RANTES were significantly higher in UPA group compared with control group, and the combination of the three cytokines have significant predictive power for predicting UPA, while the correlational analyses demonstrated that IP-10 and CXCL9 were positively correlated with BP and HR, while EGF was positively correlated with HDL. Additionally, IL-1b was suggested to be the most potential diagnostic biomarker to discriminate the APA and unilateral adrenal hyperplasia (UAH). The present findings might suggest a possibility of IP-10, CXCL9 and RANTES served as a sign to help UPA diagnosis and finally used to assist the diagnosis of APA, while IL-1b was suggested to be the most potential diagnostic biomarker to identify the APA from the UAH patients.

Peli1 deletion in macrophages attenuates myocardial ischemia/reperfusion injury by suppressing M1 polarization

The polarization of macrophages to the M1 or M2 phenotype has a pivotal role in inflammatory response following myocardial ischemia/reperfusion injury. Peli1, an E3 ubiquitin ligase, is closely associated with inflammation and autoimmunity as an important regulatory protein in the Toll-like receptor signaling pathway. We aimed to explore the function of Peli1 in macrophage polarization under myocardial ischemia/reperfusion injury and elucidate the possible mechanisms. We show here that Peli1 is upregulated in peripheral blood mononuclear cells from patients with myocardial ischemia/reperfusion, which is correlated with myocardial injury and cardiac dysfunction. We also found that the proportion of M1 macrophages was reduced and myocardial infarct size was decreased, paralleling improvement of cardiac function in mice with Peli1 deletion in hematopoietic cells or macrophages. Macrophage Peli1 deletion lessened M1 polarization and reduced the migratory ability in vitro. Mechanistically, Peli1 contributed to M1 polarization by promoting K63-linked ubiquitination and nuclear translocation of IRF5. Moreover, Peli1 deficiency in macrophages reduced the apoptosis of cardiomyocytes in vivo and in vitro. Together, our study demonstrates that Peli1 deficiency in macrophages suppresses macrophage M1 polarization and alleviates myocardial ischemia/reperfusion injury by inhibiting the nuclear translocation of IRF5, which may serve as a potential intervention target for myocardial ischemia/reperfusion injury.

TRIF/miR-34a mediates aldosterone-induced cardiac inflammation and remodeling

Aldosterone, as a major product of renin-angiotensin-aldosterone system (RAAS), determines multiple pathophysiological processes in cardiovascular diseases. The excess inflammatory response is one of the key profiles in aldosterone-mediated cardiac remodeling. However, the potential mechanisms of aldosterone/inflammatory signaling were still not fully disclosed. The present study aimed to investigate whether TIR-domain-containing adapter-inducing interferon-β (Trif) participated in the aldosterone-induced cardiac remodeling, and to explore potential molecular mechanisms. Trif knockout mice and their littermates were osmotically administrated with aldosterone (50 μg/kg per day) for 21 and 42 days. The cardiac structural analysis, functional parameters, and mitochondrial function were measured. Aldosterone dose- or time-dependently increased the levels of TRIF in primary mouse cardiomyocytes or mouse heart tissues. Trif deficiency protected against aldosterone-induced cardiac hypertrophy, fibrosis and dysfunction. Moreover, Trif deficiency also suppressed aldosterone-induced cardiac inflammatory response and mitochondrial injuries. Mechanistically, overexpression of cardiac microRNAs (miR)-34a reversed the cardiac benefits of Trif deficiency in aldosterone-treated mice. Taken together, Trif/miR-34a axis could provide a novel molecular mechanism for explaining aldosterone-induced cardiac hypertrophy, fibrosis and functional disorders.

The Impact of Glucocorticoid Co-Secretion in Primary Aldosteronism on Thyroid Autoantibody Titers During the Course of Disease

Excess aldosterone is associated with the increased risk of cardio-/cerebrovascular events as well as metabolic comorbidities not only due to its hypertensive effect but also due to its proinflammatory action. Autonomous cortisol secretion (ACS) in the setting of primary aldosteronism (PA) is known to worsen cardiovascular outcome and potentially exhibit immunosuppressive effects. The aim of this study was to determine the impact of ACS status in patients with PA on kinetics of thyroid autoantibodies (anti-TPO, anti-TG) pre and post therapy initiation. Ninety-seven PA patients (43 unilateral, 54 with bilateral PA) from the database of the German Conn's Registry were included. Anti-TPO and anti-TG levels were measured pre and 6-12 months post therapeutic intervention. Patients were assessed for ACS according to their 24- hour urinary cortisol excretion, late night salivary cortisol and low-dose dexamethasone suppression test. Abnormal test results in line with ACS were identified in 74.2% of patients with PA. Following adrenalectomy, significant increases in anti-TPO levels were observed in patients with at least one abnormal test (p = 0.049), adrenalectomized patients with at least two pathological ACS tests (p = 0.015) and adrenalectomized patients with pathologic dexamethasone suppression tests (p = 0.018). No antibody increases were observed in unilateral PA patients without ACS and in patients with bilateral PA receiving mineralocorticoid antagonist therapy (MRA). Our data are in line with an immunosuppressive effect of mild glucocorticoid excess in PA on thyroid autoantibody titers. This effect is uncovered by adrenalectomy, but not by MRA treatment.

Oxidative Stress: A Unifying Paradigm in Hypertension

The etiology of hypertension involves complex interactions among genetic, environmental, and pathophysiologic factors that influence many regulatory systems. Hypertension is characteristically associated with vascular dysfunction, cardiovascular remodelling, renal dysfunction, and stimulation of the sympathetic nervous system. Emerging evidence indicates that the immune system is also important and that activated immune cells migrate and accumulate in tissues promoting inflammation, fibrosis, and target-organ damage. Common to these processes is oxidative stress, defined as an imbalance between oxidants and antioxidants in favour of the oxidants that leads to a disruption of oxidation-reduction (redox) signalling and control and molecular damage. Physiologically, reactive oxygen species (ROS) act as signalling molecules and influence cell function through highly regulated redox-sensitive signal transduction. In hypertension, oxidative stress promotes posttranslational modification (oxidation and phosphorylation) of proteins and aberrant signalling with consequent cell and tissue damage. Many enzymatic systems generate ROS, but NADPH oxidases (Nox) are the major sources in cells of the heart, vessels, kidneys, and immune system. Expression and activity of Nox are increased in hypertension and are the major systems responsible for oxidative stress in cardiovascular disease. Here we provide a unifying concept where oxidative stress is a common mediator underlying pathophysiologic processes in hypertension. We focus on some novel concepts whereby ROS influence vascular function, aldosterone/mineralocorticoid actions, and immunoinflammation, all important processes contributing to the development of hypertension.

Mineralocorticoid Receptor-Dependent Impairment of Baroreflex Contributes to Hypertension in a Mouse Model of Primary Aldosteronism

Primary aldosteronism (PA) is the most common cause of secondary hypertension. The paucity of good animal models hinders our understanding of the pathophysiology of PA and the hypertensive mechanism of PA remains incompletely known. It was recently reported that genetic deletion of TWIK-related acid-sensitive potassium-1 and potassium-3 channels from mice (TASK^−/−) generates aldosterone excess and mild hypertension. We addressed the hypertensive mechanism by assessing autonomic regulation of cardiovascular activity in this TASK^−/− mouse line that exhibits the hallmarks of PA. Here, we demonstrate that TASK^−/− mice were hypertensive with 24-h ambulatory arterial pressure. Either systemic or central blockade of the mineralocorticoid receptor (MR) markedly reduced elevated arterial pressure to normal level in TASK^−/− mice. The response of heart rate to the muscarinic cholinergic receptor blocker atropine was similar between TASK^−/− and wild-type mice. However, the responses of heart rate to the β-adrenergic receptor blocker propranolol and of arterial pressure to the ganglion blocker hexamethonium were enhanced in TASK^−/− mice relative to the counterparts. Moreover, the bradycardiac rather than tachycardiac gain of the arterial baroreflex was significantly attenuated and blockade of MRs to a large degree rescued the dysautonomia and baroreflex gain in TASK^−/− mice. Overall, the present study suggests that the MR-dependent dysautonomia and reduced baroreflex gain contribute to the development of hyperaldosteronism-related hypertension.

Aldosterone and cardiovascular remodelling: focus on myocardial failure

Heart failure is a clinical syndrome that may result from different disease states or conditions that injure the myocardium. The activation of circulating neurohormones, particularly aldosterone, may play a pivotal role in left ventricular (LV) remodelling. The Randomized Aldactone Evaluation Study and Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival trial have emphasised the clinical importance of aldosterone. This review addresses some of the proposed mechanisms of LV remodelling in heart failure.

Aldosterone Antagonism in an Inflammatory State: Evidence for Myocardial Protection

Introduction. Chagas' disease is one of the most important causes of dilated cardiomyopathy in South and Central America. It is an inflammatory cardiomyopathy. We wanted to investigate whether it could have the same response to aldosterone antagonism as demonstrated before in other dilated cardiomyopathies.

Objective. To evaluate the role of spironolactone in myocardial remodelling in a Chagas' cardiomyopathy model.

Material and Methods. We studied 60 Sirius Hamsters divided into: control (C) infected (Inf) and Inf plus spironolactone (Infsp, 40 mg/kg/day) groups, for 11 months. Echocardiography with colour doppler was performed. Left ventricular end diastolic diameter (LVEDD), fractional shortening (FS) and corrected isovolumic relaxation time (IRT) were evaluated, as well as interstitial collagen volume fraction (ICVF) and myocardial inflammation.

Result. The results demonstrated that survival was improved by use of spironolactone in the chronic phase (p<0.04). Body weight (BW) was C:190 g, Inf:167 g*, Infsp:198 g (*p<0.05, compared to C and Infsp), LVEDD/BW was C:0.31, Inf: 0.35*, Infsp: 0.29 (*p<0.05, compared to C and Infsp), FS was C:38, Inf: 35.5, Infsp: 38 (with no statistical difference) and IRT was C: 23 msec, Inf: 26 msec*, Infsp: 22 msec (p<0.05, compared to C and Infsp). ICVF (%) was attenuated at LV (C: 0.34±0.1, Inf: 1.75±0.7*†, Infsp: 0.95±0.2*; *p<0.05, †p<0.05).

Conclusion. Spironolactone attenuated the myocardial remodelling in Chagas' cardiomyopathy, reduced mortality during the chronic phase and reduced inflammatory infiltration.

Novel Molecular Approaches in Heart Failure: Seven Trans-Membrane Receptors Signaling in the Heart and Circulating Blood Leukocytes

Heart failure (HF) is the result of molecular, cellular, and structural changes induced by cardiac load or injury. A complex network of signaling pathways have been involved in the development and progression of cardiac dysfunction. In this review, we summarize the pivotal role of seven trans-membrane receptors (7TMRs), also called G-protein-coupled receptors (GPCRs), in HF. Moreover, we will discuss the current knowledge on the potential mirroring of 7TMR signaling between circulating blood leukocytes and the heart, and the related future possibilities in the management of HF patients.

Myeloid mineralocorticoid receptor deficiency inhibits aortic constriction-induced cardiac hypertrophy in mice

Mineralocorticoid receptor (MR) blockade has been shown to suppress cardiac hypertrophy and remodeling in animal models of pressure overload (POL). This study aims to determine whether MR deficiency in myeloid cells modulates aortic constriction-induced cardiovascular injuries. Myeloid MR knockout (MMRKO) mice and littermate control mice were subjected to abdominal aortic constriction (AAC) or sham operation. We found that AAC-induced cardiac hypertrophy and fibrosis were significantly attenuated in MMRKO mice. Expression of genes important in generating reactive oxygen species was decreased in MMRKO mice, while that of manganese superoxide dismutase increased. Furthermore, expression of genes important in cardiac metabolism was increased in MMRKO hearts. Macrophage infiltration in the heart was inhibited and expression of inflammatory genes was decreased in MMRKO mice. In addition, aortic fibrosis and inflammation were attenuated in MMRKO mice. Taken together, our data indicated that MR deficiency in myeloid cells effectively attenuated aortic constriction-induced cardiac hypertrophy and fibrosis, as well as aortic fibrosis and inflammation.

Atrophic cardiomyocyte signaling in hypertensive heart disease

Cardinal pathological features of hypertensive heart disease (HHD) include not only hypertrophied cardiomyocytes and foci of scattered microscopic scarring, a footprint of prior necrosis, but also small myocytes ensnared by fibrillar collagen where disuse atrophy with protein degradation would be predicted. Whether atrophic signaling is concordant with the appearance of HHD and involves oxidative and endoplasmic reticulum (ER) stress remains unexplored. Herein, we examine these possibilities focusing on the left ventricle and cardiomyocytes harvested from hypertensive rats receiving 4 weeks aldosterone/salt treatment (ALDOST) alone or together with ZnSO₄, a nonvasoactive antioxidant, with the potential to attenuate atrophy and optimize hypertrophy. Compared with untreated age-/sex-/strain-matched controls, ALDOST was accompanied by (1) left ventricle hypertrophy with preserved systolic function; (2) concordant cardiomyocyte atrophy (<1000 μm²) found at sites bordering on fibrosis where they were reexpressing β-myosin heavy chain; and (3) upregulation of ubiquitin ligases, muscle RING-finger protein-1 and atrogin-1, and elevated 8-isoprostane and unfolded protein ER response with messenger RNA upregulation of stress markers. ZnSO₄ cotreatment reduced lipid peroxidation, fibrosis, and the number of atrophic myocytes, together with a further increase in cell area and width of atrophied and hypertrophied myocytes, and improved systolic function but did not attenuate elevated blood pressure. We conclude that atrophic signaling, concordant with hypertrophy, occurs in the presence of a reparative fibrosis and induction of oxidative and ER stress at sites of scarring where myocytes are atrophied. ZnSO₄ cotreatment in HHD with ALDOST attenuates the number of atrophic myocytes, optimizes size of atrophied and hypertrophied myocytes, and improves systolic function.

Mineralocorticoid receptor signaling reduces numbers of circulating human naïve T cells and increases their CD62L, CCR7, and CXCR4 expression

The role of mineralocorticoid receptors (MRs) in human T-cell migration is not yet understood. We have recently shown that the MR antagonist spironolactone selectively increases the numbers of circulating naïve and central memory T cells during early sleep, which is the time period in the 24 h cycle hallmarked by predominant MR activation. To investigate whether this effect is specific to spironolactone's blockade of MRs and to study the underlying molecular mechanisms, healthy humans were given the selective MR-agonist fludrocortisone or placebo and numbers of eight T-cell subsets and their CD62L and CXCR4 expression were analyzed. Fludrocortisone selectively reduced counts of naïve CD4(+) , central memory CD4(+), and naïve CD8(+) T cells and increased CXCR4 expression on the naïve subsets. In complementing in vitro studies, fludrocortisone enhanced CXCR4 and CD62L expression, which was counteracted by spironolactone. Incubation of naïve T cells with spironolactone alone reduced CD62L and CCR7 expression. Our results indicate a regulatory influence of MR signaling on human T-cell migration and suggest a role for endogenous aldosterone in the redistribution of T-cell subsets to lymph nodes, involving CD62L, CCR7, and CXCR4. Facilitation of T-cell homing following sleep-dependent aldosterone release might thus essentially contribute to sleep's well-known role in supporting adaptive immunity.

Cardiovascular remodelling in coronary artery disease and heart failure

Remodelling is a response of the myocardium and vasculature to a range of potentially noxious haemodynamic, metabolic, and inflammatory stimuli. Remodelling is initially functional, compensatory, and adaptive but, when sustained, progresses to structural changes that become self-perpetuating and pathogenic. Remodelling involves responses not only of the cardiomyocytes, endothelium, and vascular smooth muscle cells, but also of interstitial cells and matrix. In this Review we characterise the remodelling processes in atherosclerosis, vascular and myocardial ischaemia-reperfusion injury, and heart failure, and we draw attention to potential avenues for innovative therapeutic approaches, including conditioning and metabolic strategies.

Spironolactone decreases DOCA-salt-induced organ damage by blocking the activation of T helper 17 and the downregulation of regulatory T lymphocytes

Adaptive immune response has been implicated in inflammation and fibrosis as a result of exposure to mineralocorticoids and a high-salt diet. We hypothesized that in mineralocorticoid-salt-induced hypertension, activation of the mineralocorticoid receptor alters the T-helper 17 lymphocyte (Th17)/regulatory T-lymphocyte/interleukin-17 (IL-17) pathway, contributing to cardiac and renal damage. We studied the inflammatory response and tissue damage in rats treated with deoxycorticosterone acetate and high-salt diet (DOCA-salt), with or without mineralocorticoid receptor inhibition by spironolactone. To determine whether Th17 differentiation in DOCA-salt rats is caused by hypertension per se, DOCA-salt rats received antihypertensive therapy. In addition, to evaluate the pathogenic role of IL-17 in hypertension and tissue damage, we studied the effect of IL-17 blockade with a specific antibody (anti-IL-17). We found activation of Th17 cells and downregulation of forkhead box P3 mRNA in peripheral tissues, heart, and kidneys of DOCA-salt-treated rats. Spironolactone treatment prevented Th17 cell activation and increased numbers of forkhead box P3-positive cells relative to DOCA-salt rats. Antihypertensive therapy did not ameliorate Th17 activation in rats. Treatment of DOCA-salt rats with anti-IL-17 significantly reduced arterial hypertension as well as expression of profibrotic and proinflammatory mediators and collagen deposits in the heart and kidney. We conclude that mineralocorticoid receptor activation alters the Th17/regulatory T-lymphocyte/IL-17 pathway in mineralocorticoid-dependent hypertension as part of an inflammatory mechanism contributing to fibrosis.

Phosphoproteome mapping of cardiomyocyte mitochondria in a rat model of heart failure

Mitochondria are complex organelles essential to cardiomyocyte survival. Protein phosphorylation is emerging as a key regulator of mitochondrial function. In the study reported here, we analyzed subsarcolemmal (SSM) mitochondria harvested from rats who have received 4 weeks of aldosterone/salt treatment to simulate the neurohormonal profile of human congestive heart failure. Our objective was to obtain an initial qualitative inventory of the phosphoproteins in this biologic system. SSM mitochondria were harvested, and the phosphoproteome was analyzed with a gel-free bioanalytical platform. Mitochondrial proteins were digested with trypsin, and the digests were enriched for phosphopeptides with immobilized metal ion affinity chromatography. The phosphopeptides were analyzed by ion trap liquid chromatography-tandem mass spectrometry, and the phosphoproteins identified via database searches. Based on MS/MS and MS(3) data, we characterized a set of 42 phosphopeptides that encompassed 39 phosphorylation sites. These peptides mapped to 26 proteins, for example, long-chain specific acyl-CoA dehydrogenase, Complex III subunit 6, and mitochondrial import receptor TOM70. Collectively, the characterized phosphoproteins belong to diverse functional modules, including bioenergetic pathways, protein import machinery, and calcium handling. The phosphoprotein panel discovered in this study provides a foundation for future differential phosphoproteome profiling toward an integrated understanding of the role of mitochondrial phosphorylation in heart failure.

Gene Expression Profiles of Peripheral Blood Mononuclear Cells Reveal Transcriptional Signatures as Novel Biomarkers for Cardiac Remodeling in Rats with Aldosteronism and Hypertensive Heart Disease

OBJECTIVES

In searching for a noninvasive surrogate tissue having mimicry with the prooxidant/-proinflammatory hypertensive heart disease (HHD) phenotype, we turned to peripheral blood mononuclear cells (PBMC). We tested whether iterations in [Ca²⁺]_i, [Zn²⁺]_i and oxidative stress in cardiomyocytes and PBMC would complement each other eliciting similar shifts in gene expression profiles in these tissues demonstrable during preclinical (wk 1) and pathologic (wk 4) stages of aldosterone/salt treatment (ALDOST).

BACKGROUND

Inappropriate neurohormonal activation contributes to pathologic remodeling of myocardium in HHD associated with aldosteronism. In rats receiving chronic ALDOST, evidence of reparative fibrosis replacing necrotic cardiomyocytes and coronary vasculopathy appears at wk 4 associated with the induction of oxidative stress by mitochondria that overwhelms endogenous, largely Zn²⁺-based, antioxidant defenses. Biomarker-guided prediction of risk prior to the appearance of cardiac pathology would prove invaluable.

METHODS

In PBMC and cardiomyocytes, quantitation of cytoplasmic free Ca²⁺ and Zn²⁺, H₂O₂ and 8-iosprostane levels, as well as isolation of RNA and gene expression, together with statistical and clustering analyses, and confirmation of genes by in situ hybridization and RT-PCR, were performed.

RESULTS

Compared to controls, at wk 1 and 4 ALDOST, we found comparable: increments in [Ca²⁺]_i, [Zn²⁺]_i and 8-isoprotane coupled to increased H₂O₂ production in cardiac mitochondria and PBMC, together with the common networks of expression profiles dominated by genes involved in oxidative stress, inflammation and repair. These included three central Ingenuity pathway-linked genes: p38MAPK, a stress-responsive protein; NFκB, a redox-sensitive transcription factor and a proinflammatory cascade it regulates; and TGF-β₁, a fibrogenic cytokine involved in tissue repair.

CONCLUSIONS

Significant overlapping demonstrated in the molecular mimicry of PBMC and cardiomyocytes during preclinical and pathologic stages of ALDOST implicates that transcriptional signatures of PBMC may serve as early noninvasive and novel sentinels predictive of impending pathologic remodeling in HHD.

Ketamine, magnesium and major depression--from pharmacology to pathophysiology and back

The glutamatergic mechanism of antidepressant treatments is now in the center of research to overcome the limitations of monoamine-based approaches. There are several unresolved issues. For the action of the model compound, ketamine, NMDA-receptor block, AMPA-receptor activation and BDNF release appear to be involved in a mechanism, which leads to synaptic sprouting and strengthened synaptic connections. The link to the pathophysiology of depression is not clear. An overlooked connection is the role of magnesium, which acts as physiological NMDA-receptor antagonist: 1. There is overlap between the actions of ketamine with that of high doses of magnesium in animal models, finally leading to synaptic sprouting. 2. Magnesium and ketamine lead to synaptic strengthening, as measured by an increase in slow wave sleep in humans. 3. Pathophysiological mechanisms, which have been identified as risk factors for depression, lead to a reduction of (intracellular) magnesium. These are neuroendocrine changes (increased cortisol and aldosterone) and diabetes mellitus as well as Mg(2+) deficiency. 4. Patients with therapy refractory depression appear to have lower CNS Mg(2+) levels in comparison to health controls. 5. Experimental Mg(2+) depletion leads to depression- and anxiety like behavior in animal models. 6. Ketamine, directly or indirectly via non-NMDA glutamate receptor activation, acts to increase brain Mg(2+) levels. Similar effects have been observed with other classes of antidepressants. 7. Depressed patients with low Mg(2+) levels tend to be therapy refractory. Accordingly, administration of Mg(2+) either alone or in combination with standard antidepressants acts synergistically on depression like behavior in animal models.

CONCLUSION

On the basis of the potential pathophysiological role of Mg(2+)-regulation, it may be possible to predict the action of ketamine and of related compounds based on Mg(2+) levels. Furthermore, screening for compounds to increase neuronal Mg(2+) concentration could be a promising instrument to identify new classes of antidepressants. Overall, any discussion of the glutamatergic system in affective disorders should consider the role of Mg(2+).

Myofibroblast-mediated mechanisms of pathological remodelling of the heart

The syncytium of cardiomyocytes in the heart is tethered within a matrix composed principally of type I fibrillar collagen. The matrix has diverse mechanical functions that ensure the optimal contractile efficiency of this muscular pump. In the diseased heart, cardiomyocytes are lost to necrotic cell death, and phenotypically transformed fibroblast-like cells-termed 'myofibroblasts'-are activated to initiate a 'reparative' fibrosis. The structural integrity of the myocardium is preserved by this scar tissue, although at the expense of its remodelled architecture, which has increased tissue stiffness and propensity to arrhythmias. A persisting population of activated myofibroblasts turns this fibrous tissue into a living 'secretome' that generates angiotensin II and its type 1 receptor, and fibrogenic growth factors (such as transforming growth factor-β), all of which collectively act as a signal-transducer-effector signalling pathway to type I collagen synthesis and, therefore, fibrosis. Persistent myofibroblasts, and the resultant fibrous tissue they produce, cause progressive adverse myocardial remodelling, a pathological hallmark of the failing heart irrespective of its etiologic origin. Herein, we review relevant cellular, subcellular, and molecular mechanisms integral to cardiac fibrosis and consequent remodelling of atria and ventricles with a heterogeneity in cardiomyocyte size. Signalling pathways that antagonize collagen fibrillogenesis provide novel strategies for cardioprotection.

Corticosteroids, heart failure, and hypertension: a role for immune cells?

Aldosterone and its receptor the mineralocorticoid receptor (MR) are best known for their regulation of fluid and electrolyte homeostasis in epithelial cells. However, it is now clear that MR are also expressed in a broad range of nonepithelial tissues including the cardiovascular system. In the heart and vascular tissues, pathological activation of MR promotes cardiovascular inflammation and remodeling for which there is increasing evidence that macrophages and other immune cells (e.g. T cells and dendritic cells) play a significant role. While the glucocorticoids and their receptors have well-described antiinflammatory actions in immune cells, a role for aldosterone and/or the MR in these cells is largely undefined. Emerging evidence, however, suggests that MR signaling may directly or indirectly promote proinflammatory responses in these immune cells. This review will discuss the current understanding of the role of corticosteroid receptors in macrophages and their effect on cardiovascular diseases involving inflammation.

Aldosterone, oxidative stress, and NF-κB activation in hypertension-related cardiovascular and renal diseases

The mineralocorticoid aldosterone regulates electrolyte and fluid balance and is involved in blood pressure homoeostasis. Classically, it binds to its intracellular mineralocorticoid receptor to induce expression of proteins influencing the reabsorption of sodium and water in the distal nephron. Aldosterone gained special attention when large clinical studies showed that blocking its receptor in patients with cardiovascular diseases reduced their mortality. These patients present increased plasma aldosterone levels. The exact mechanisms of the potential toxic effects of aldosterone leading to cardiovascular damage are not known yet. The observation of reduced nitric oxide bioavailability in hyperaldosteronism implied the generation of oxidative stress by aldosterone. Subsequent studies confirmed the increase of oxidative stress markers in patients with chronic heart failure and in animal models of hyperaldosteronism. The effects of reactive oxygen species have been related to the activation of transcription factors, such as NF-κB. This review summarizes the present-day knowledge of aldosterone-induced oxidative stress and NF-κB activation in humans and different experimental models.

Mitochondriocentric pathway to cardiomyocyte necrosis in aldosteronism: cardioprotective responses to carvedilol and nebivolol

Foci of fibrosis, footprints of cardiomyocyte necrosis, are scattered throughout the failing myocardium and are a major component to its pathologic remodeling. Understanding pathogenic mechanisms contributing to hormone-mediated necrosis is therefore fundamental to developing cardioprotective strategies. In this context, a mitochondriocentric signal-transducer-effector pathway to necrosis is emerging. Our first objective, using cardiomyocytes and subsarcolemmal mitochondria (SSM) harvested from rats receiving a 4-week aldosterone/salt treatment (ALDOST), was to identify the major components of this pathway. Second, to validate this pathway, we used mitochondria-targeted pharmaceutical interventions as cardioprotective strategies using 4-week cotreatment with either carvedilol (Carv) or nebivolol (Nebiv). Compared with controls, we found the 4-week ALDOST to be accompanied by elevated cardiomyocyte free [Ca(2+)]i and SSM free [Ca(2+)]m; increased H(2)O(2) production and 8-isoprostane in SSM, cardiac tissue, and plasma; and enhanced opening of mitochondrial permeability transition pore (mPTP) and myocardial scarring. Increments in the antioxidant capacity augmented by increased cytosolic free [Zn(2+)]i were overwhelmed. Cotreatment with either Carv or Nebiv attenuated [Ca(2+)]i and [Ca(2+)]m overloading, prevented oxidative stress, and reduced mPTP opening while augmenting [Zn(2+)]i and conferring cardioprotection. Thus, major components of the mitochondriocentric signal-transducer-effector pathway to cardiomyocyte necrosis seen with ALDOST include intracellular Ca overloading coupled to oxidative stress and mPTP opening. This subcellular pathway can be favorably regulated by Carv or Nebiv cotreatment to salvage cardiomyocytes and prevent fibrosis.

Predictors of hyperkalemia and death in patients with cardiac and renal disease

Predictors of hyperkalemia in patients with cardiovascular disease (CVD; defined as patients with hypertension and heart failure) and associated chronic kidney disease (CKD) are not well established. The aim of this study was to ascertain risk factors of hyperkalemia (defined as serum potassium concentration >5.0 mEq/L) and associated all-cause mortality in patients with CVD treated with antihypertensive drugs that impair potassium homeostasis. In a retrospective analysis using a logistic regression model, risk factors for hyperkalemia and all-cause mortality were analyzed in 15,803 patients with CVD treated with antihypertensive drugs. The mean estimated glomerular filtration rate and mean serum potassium concentration were 55.55 ml/min/1.73 m(2) and 4.06 mEq/L, respectively. Hyperkalemia was observed in 24.5% of study patients and 1.7% of total hospital admissions. Compared to patients with normokalemia, those with hyperkalemia had a higher percentage of death (6.25% vs 2.92%, p = 0.0001) and admissions (7.80% vs 5.04%, p = 0.0001). Predictors of hyperkalemia were CKD stage (odds ratio [OR] 2.14, 95% confidence interval [CI] 2.02 to 2.28), diabetes mellitus (OR 1.59, 95% CI 1.47 to 1.72), coronary artery disease (OR 1.32, 95% CI 1.21 to 1.43), and peripheral vascular disease (OR 1.55, 95% CI 1.36 to 1.77). Predictors of all-cause mortality were CKD stage (OR 1.26, 95% CI 1.12 to 1.43), hyperkalemic event (OR 1.56, 95% CI 1.30 to 1.88), age (OR 1.04, 95% CI 1.03 to 1.05), and hospitalization (OR 1.04, 95% CI 1.04 to 1.05). In conclusion, hyperkalemia is encountered frequently in patients with established CVD who are taking antihypertensive drugs and is associated with increases in all-cause mortality and hospitalizations. Advanced CKD, diabetes mellitus, coronary artery disease, and peripheral vascular disease are independent predictors of hyperkalemia.

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.

Effect of aldosterone on the amplification of oncolytic vaccinia virus in human cancer lines

BACKGROUND/AIMS

JX-594 is an oncolytic virus derived from the Wyeth vaccinia strain that causes replication-dependent cytolysis and antitumor immunity. Starting with a cross-examination of clinical-trial samples from advanced hepatocellular carcinoma patients having high levels of aldosterone and virus amplification in JX-594 treatment, we investigated the association between virus amplification and aldosterone in human cancer cell lines.

METHODS

Cell proliferation was determined by a cell-counting-kit-based colorimetric assay, and vaccinia virus quantitation was performed by quantitative polymerase chain reaction (qPCR) and a viral plaque assay. Also, the intracellular pH was measured using a pH-sensitive dye.

RESULTS

Simultaneous treatment with JX-594 and aldosterone significantly increased viral replication in A2780, PC-3, and HepG2 cell lines, but not in U2OS cell lines. Furthermore, the aldosterone treatment time altered the JX-594 replication according to the cell line. The JX-594 replication peaked after 48 and 24 hours of treatment in PC-3 and HepG2 cells, respectively. qPCR showed that JX-594 entry across the plasma membrane was increased, however, the changes are not significant by the treatment. This was inhibited by treatment with spironolactone (an aldosterone-receptor inhibitor). JX-594 entry was significantly decreased by treatment with EIPA [5-(N-ethyl-N-isopropyl)amiloride; a Na(+)/H(+)-exchange inhibitor], but aldosterone significantly restored JX-594 entry even in the presence of EIPA. Intracellular alkalization was observed after aldosterone treatment but was acidified by EIPA treatment.

CONCLUSIONS

Aldosterone stimulates JX-594 amplification via increased virus entry by affecting the H(+) gradient.

Subchronic treatment with aldosterone induces depression-like behaviours and gene expression changes relevant to major depressive disorder

The potential role of aldosterone in the pathophysiology of depression is unclear. The aim of this study was to test the hypothesis that prolonged elevation of circulating aldosterone induces depression-like behaviour accompanied by disease-relevant changes in gene expression in the hippocampus. Subchronic (2-wk) treatment with aldosterone (2 μg/100 g body weight per day) or vehicle via subcutaneous osmotic minipumps was used to induce hyperaldosteronism in male rats. All rats (n = 20/treatment group) underwent a modified sucrose preference test. Half of the animals from each treatment group were exposed to the forced swim test (FST), which served both as a tool to assess depression-like behaviour and as a stress stimulus. Affymetrix microarray analysis was used to screen the entire rat genome for gene expression changes in the hippocampus. Aldosterone treatment induced an anhedonic state manifested by decreased sucrose preference. In the FST, depressogenic action of aldosterone was manifested by decreased latency to immobility and increased time spent immobile. Aldosterone treatment resulted in transcriptional changes of genes in the hippocampus involved in inflammation, glutamatergic activity, and synaptic and neuritic remodelling. Furthermore, aldosterone-regulated genes substantially overlapped with genes affected by stress in the FST. This study demonstrates the existence of a causal relationship between the hyperaldosteronism and depressive behaviour. In addition, aldosterone treatment induced changes in gene expression that may be relevant to the aetiology of major depressive disorder. Subchronic treatment with aldosterone represents a new animal model of depression, which may contribute to the development of novel targets for the treatment of depression.

Aldosterone as a modulator of immunity: implications in the organ damage

High plasmatic levels of aldosterone cause hypertension and contribute to progressive organ damage to the heart, vasculature, and kidneys. Recent studies have demonstrated a role for the immune system in these pathological processes. Aldosterone promotes an inflammatory state characterized by vascular infiltration of immune cells, reactive oxidative stress, and proinflammatory cytokine production. Further, cells of the adaptive immune system, such as T cells, seem to participate in the genesis of mineralocorticoid hormone-induced hypertension. In addition, the observation that aldosterone can promote CD4⁺ T-cell activation and Th17 polarization suggests that this hormone could contribute to the onset of autoimmunity. Here we discuss recent evidence supporting a significant involvement of the immune system, especially adaptive immunity, in the genesis of hypertension and organ damage induced by primary aldosteronism. In addition, possible new therapeutic approaches consisting of immunomodulator drugs to control exacerbated immune responses triggered by elevated aldosterone concentrations will be described.

Zinc and copper levels in severe heart failure and the effects of atrial fibrillation on the zinc and copper status

Oxidative stress is involved in the pathogenesis of congestive heart failure (CHF). Some trace elements serve as antioxidant defenses. The purpose of this study was to analyze the effect of atrial fibrillation (AF) on zinc (Zn) and copper (Cu) levels in patients with advanced CHF. In this prospective study, serum Zn and Cu levels in 78 patients with clinically advanced CHF, i.e., New York Heart Association (NYHA) functional class III or IV (40 patients with AF and 38 in sinus rhythm) were measured using atomic absorption spectrophotometry. All patients also had a left ventricular ejection fraction (EF) of <35%. We recruited 40 volunteers with nearly the same age and weight as control. They had normal EF. There was no significant difference between patients with AF and those with sinus rhythm regarding serum Zn and Cu levels. However, both groups showed significant hypozincemia (p < 0.000) and a decreased Zn/Cu ratio (p < 0.03) compared with control group. Serum Cu levels were similar in the two groups and did not differ significantly from the control group. In patients with advanced CHF, irrespective of the rhythm, profound hypozincemia, and a decreased Zn/Cu ratio were present, which could be secondary to the activation of the renin-angiotensin-aldosterone system and CHF medications. The results suggest the need for more studies focusing on possible benefits with Zn nutriceutical replacement in patients with advanced CHF.

Usefulness of total lymphocyte count as predictor of outcome in patients with chronic heart failure

Low lymphocyte count has been considered a predictive marker of unfavorable outcomes for patients with heart failure (HF). Baseline blood samples for complete blood counts, differential counts, renal function tests. and lipid profile were prospectively obtained to assess the association between lymphocyte count and clinical outcomes in 305 patients with HF (average New York Heart Association [NYHA] class 2.8). The mean follow-up duration was 4.7 years (range 8 months to 8.4 years), and 111 patients (36%) died during the follow-up period. The mean lymphocyte count for the group was 1,803.64 ± 740.3, and the mean left ventricular ejection fraction (LVEF) was 37%. Patients with low lymphocyte counts (<1,600 median count) after 8 years had significantly lower survival rates than those with lymphocyte counts ≥1,600 (58% vs 72%, p=0.012). The prediction of poorest survival was for patients in NYHA class III or IV and with lymphocyte counts <1,600. Regression analysis showed that lymphocyte level, the LVEF, and NYHA class were predictors of mortality. Of these, NYHA class was the most prominent predictor, followed by lymphocyte count, which was even more significant than the LVEF (hazard ratio 0.76, p=0.037). In conclusion, the findings of this study demonstrate that total lymphocyte count is an important prognostic factor, inversely associated with predicted mortality. Although the total low lymphocyte count was correlated with a lower NYHA class and a lower LVEF, it emerged as an independent death risk factor in patients with chronic HF.

Cellular and molecular pathways to myocardial necrosis and replacement fibrosis

Fibrosis is a fundamental component of the adverse structural remodeling of myocardium present in the failing heart. Replacement fibrosis appears at sites of previous cardiomyocyte necrosis to preserve the structural integrity of the myocardium, but not without adverse functional consequences. The extensive nature of this microscopic scarring suggests cardiomyocyte necrosis is widespread and the loss of these contractile elements, combined with fibrous tissue deposition in the form of a stiff in-series and in-parallel elastic elements, contributes to the progressive failure of this normally efficient muscular pump. Cellular and molecular studies into the signal-transducer-effector pathway involved in cardiomyocyte necrosis have identified the crucial pathogenic role of intracellular Ca2+ overloading and subsequent induction of oxidative stress, predominantly confined within its mitochondria, to be followed by the opening of the mitochondrial permeability transition pore that leads to the destruction of these organelles and cells. It is now further recognized that Ca2+ overloading of cardiac myocytes and mitochondria serves as a prooxidant and which is counterbalanced by an intrinsically coupled Zn2+ entry serving as antioxidant. The prospect of raising antioxidant defenses by increasing intracellular Zn2+ with adjuvant nutriceuticals can, therefore, be preferentially exploited to uncouple this intrinsically coupled Ca2+ - Zn2+ dyshomeostasis. Hence, novel yet simple cardioprotective strategies may be at hand that deserve to be further explored.

Congestive heart failure: where homeostasis begets dyshomeostasis

Despite today's standard of care, aimed at preventing homeostatic neurohormonal activation, one in every five patients recently hospitalized with congestive heart failure (CHF) will be readmitted within 30 days of discharge because of a recurrence of their symptoms and signs. In light of recent pathophysiological insights, it is now propitious to revisit CHF with a view toward complementary and evolving management strategies. CHF is a progressive systemic illness. Its features include: oxidative stress in diverse tissues; an immunostimulatory state with circulating proinflammatory cytokines; a wasting of soft tissues; and a resorption of bone. Its origins are rooted in homeostatic mechanisms gone awry to beget dyshomeostasis. For example, marked excretory losses of Ca2+ and Mg2+ accompany renin-angiotensin-aldosterone system activation, causing ionized hypocalcemia and hypomagnesemia that lead to secondary hyperparathyroidism with consequent bone resorption and a propensity to atraumatic fractures. Parathyroid hormone accounts for paradoxical intracellular Ca2+ overloading in diverse tissues and consequent systemic induction of oxidative stress. In cardiac myocytes and mitochondria, these events orchestrate opening of the mitochondrial permeability transition pore with an ensuing osmotic-based destruction of these organelles and resultant cardiomyocyte necrosis with myocardial scarring. Contemporaneous with Ca2+ and Mg2+ dyshomeostasis is hypozincemia and hyposelenemia, which compromise metalloenzyme-based antioxidant defenses, whereas hypovitaminosis D threatens Ca2+ stores needed to prevent secondary hyperparathyroidism. An intrinsically coupled dyshomeostasis of intracellular Ca2+ and Zn2+, representing pro-oxidant and antioxidant, respectively, is integral to regulating the mitochondrial redox state; it can be uncoupled by a Zn2+ supplement in favor of antioxidant defenses. Hence, the complementary use of nutriceuticals to nullify dyshomeostatic responses involving macro- and micronutrients should be considered. Evolving strategies with mitochondria-targeted interventions interfering with their uptake of Ca2+ or serving as selective antioxidant or mitochondrial permeability transition pore inhibitor may also prove efficacious in the overall management of CHF.

Fibrosis in hypertensive heart disease: molecular pathways and cardioprotective strategies

Fibrosis is a fundamental component of the adverse structural remodelling of myocardium found in hypertensive heart disease (HHD). A replacement fibrosis appears at sites of previous cardiomyocyte necrosis to preserve the structural integrity of the myocardium. Such scarring has adverse functional consequences. The extensive distribution of fibrosis involving the right and left heart suggests cardiomyocyte necrosis is widespread. Together, the loss of these contractile elements and fibrous tissue deposition in the form of stiff in-series and in-parallel elastic elements contribute to the progressive failure of this normally efficient muscular pump. Pathogenic mechanisms modulating fibrous tissue formation at sites of repair include auto/paracrine properties of locally generated angiotensin II and endothelin-1. This study focuses on the signal-transducer-effector pathway involved in cardiomyocyte necrosis and the crucial pathogenic role of intracellular calcium overloading, and the subsequent induction of oxidative stress originating within its mitochondria that dictates the opening of the mitochondrial permeability transition pore. The ensuing osmotic destruction of these organelles is followed by necrotic cell death. It is now further recognized that calcium overloading of cardiac myocytes and mitochondria functioning as pro-oxidant is pathophysiologically counterbalanced by an intrinsically coupled zinc entry, which serves as an antioxidant. The prospect of raising intracellular zinc by adjuvant nutriceutical supplementation can, therefore, be preferentially exploited to uncouple this intrinsically coupled calcium-zinc dyshomeostasis in favour of endogenous antioxidant defences. Novel cardioprotective strategies may thus be at hand and deserve to be explored further in the overall management of patients with HHD.

Spironolactone inhibits NADPH oxidase-induced oxidative stress and enhances eNOS in human endothelial cells

Accumulating evidence indicates that aldosterone plays a critical role in the mediation of oxidative stress and vascular damage. NADPH oxidase has been recognized as a major source of oxidative stress in vasculature. However, the relation between NADPH oxidase in aldosterone-mediated oxidative stress in endothelial cells remains to be ascertained. The present study aimed to investigate the relevant role of NADPH oxidase in aldosterone induced oxidative stress and the functional consequence of this effect on endothelial function. Additionally, we attempted to examine the potential role of the mineralocorticoid receptor (MR) antagonist; spironolactone (spiro) in this scenario. Human umbilical artery endothelial cells (HUAECs) were incubated with aldosterone (100 nmol/L, 24 h) in the absence and presence of Spiro (1 µmol/L). The results showed that aldosterone significantly increased the protein expression of NADPH oxidase subunits (Nox2, p47(phox) and p22(phox)) and that spiro markedly inhibited these changes. Functionally, this was associated with an elevation in NADPH oxidase activity and 3-nitrotyrosine (3-NT) as a biochemical marker of oxidative stress. However, pre-incubation with spiro inhibited these consequences. Moreover, MR protein expression was upregulated by aldosterone whereas this effect was suppressed by Spiro. While aldosterone effectively inhibited endothelial nitric oxide (eNOS) protein expression, pretreatment with spiro markedly restored it to its normal level. In conclusion, the results achieved suggest that aldosterone may play a critical role in NADPH oxidase-mediated oxidative stress resulting in reduced eNOS expression in human endothelial cells. Spiro effectively reversed these consequences, suggesting its potential vasculoprotective effect in endothelial dysfunction.

Myeloid-specific deletion of the mineralocorticoid receptor reduces infarct volume and alters inflammation during cerebral ischemia

BACKGROUND AND PURPOSE

mineralocorticoid receptor (MR) antagonists have protective effects in rodent models of ischemic stroke, but the cell type-specific actions of these drugs are unknown. In the present study, we examined the contribution of myeloid cell MR during focal cerebral ischemia using myeloid-specific MR knockout mice.

METHODS

myeloid-specific MR knockout mice were subjected to transient (90 minutes) middle cerebral artery occlusion followed by 24 hours reperfusion (n=5 to 7 per group). Ischemic cerebral infarcts were identified by hematoxylin and eosin staining and quantified with image analysis software. Immunohistochemical localization of microglia and macrophages was performed using Iba1 staining, and the expression of inflammatory markers was measured after 24 hours of reperfusion by quantitative reverse transcription-polymerase chain reaction.

RESULTS

myeloid-specific MR knockout resulted in a 65% reduction in infarct volume (P=0.005) after middle cerebral artery occlusion. This was accompanied by a significant reduction in activated microglia and macrophages in the ischemic core. Furthermore, myeloid-specific MR knockout suppressed classically activated M1 macrophage markers tumor necrosis factor-α, interleukin-1β, monocyte chemoattractant protein-1, macrophage inflammatory protein-1α, and interleukin-6 at the same time as partially preserving the induction of alternatively activated, M2, markers Arg1, and Ym1.

CONCLUSIONS

these data demonstrate that myeloid MR activation exacerbates stroke and identify myeloid MR as a critical target for MR antagonists. Furthermore, these data indicate that MR activation has an important role in controlling immune cell function during the inflammatory response to stroke.

Calcium and zinc dyshomeostasis during isoproterenol-induced acute stressor state

Acute hyperadrenergic stressor states are accompanied by cation dyshomeostasis, together with the release of cardiac troponins predictive of necrosis. The signal-transducer-effector pathway accounting for this pathophysiological scenario remains unclear. We hypothesized that a dyshomeostasis of extra- and intracellular Ca2+ and Zn2+ occurs in rats in response to isoproterenol (Isop) including excessive intracellular Ca2+ accumulation (EICA) and mitochondrial [Ca2+]m-induced oxidative stress. Contemporaneously, the selective translocation of Ca2+ and Zn2+ to tissues contributes to their fallen plasma levels. Rats received a single subcutaneous injection of Isop (1 mg/kg body wt). Other groups of rats received pretreatment for 10 days with either carvedilol (C), a β-adrenergic receptor antagonist with mitochondrial Ca2+ uniporter-inhibiting properties, or quercetin (Q), a flavonoid with mitochondrial-targeted antioxidant properties, before Isop. We monitored temporal responses in the following: [Ca2+] and [Zn2+] in plasma, left ventricular (LV) apex, equator and base, skeletal muscle, liver, spleen, and peripheral blood mononuclear cells (PBMC), indices of oxidative stress and antioxidant defenses, mitochondrial permeability transition pore (mPTP) opening, and myocardial fibrosis. We found ionized hypocalcemia and hypozincemia attributable to their tissue translocation and also a heterogeneous distribution of these cations among tissues with a preferential Ca2+ accumulation in the LV apex, muscle, and PBMC, whereas Zn2+ declined except in liver, where it increased corresponding with upregulation of metallothionein, a Zn2+-binding protein. EICA was associated with a simultaneous increase in tissue 8-isoprostane and increased [Ca2+]m accompanied by a rise in H2O2 generation, mPTP opening, and scarring, each of which were prevented by either C or Q. Thus excessive [Ca2+]m, coupled with the induction of oxidative stress and increased mPTP opening, suggests that this signal-transducer-effector pathway is responsible for Isop-induced cardiomyocyte necrosis at the LV apex.

Uncoupling the coupled calcium and zinc dyshomeostasis in cardiac myocytes and mitochondria seen in aldosteronism

Intracellular [Ca2+]i overloading in cardiomyocytes is a fundamental pathogenic event associated with chronic aldosterone/salt treatment (ALDOST) and accounts for an induction of oxidative stress that leads to necrotic cell death and consequent myocardial scarring. This prooxidant response to Ca2+ overloading in cardiac myocytes and mitochondria is intrinsically coupled to simultaneous increased Zn2+ entry serving as an antioxidant. Herein, we investigated whether Ca2+ and Zn2+ dyshomeostasis and prooxidant to antioxidant dysequilibrium seen at 4 weeks, the pathologic stage of ALDOST, could be uncoupled in favor of antioxidants, using cotreatment with a ZnSO4 supplement; pyrrolidine dithiocarbamate (PDTC), a Zn2+ ionophore; or ZnSO4 in combination with amlodipine (Amlod), a Ca2+ channel blocker. We monitored and compared responses in cardiomyocyte free [Ca2+]i and [Zn2+]i together with biomarkers of oxidative stress in cardiac myocytes and mitochondria. At week 4 of ALDOST and compared with controls, we found (1) an elevation in [Ca2+]i coupled with [Zn2+]i and (2) increased mitochondrial H2O2 production and increased mitochondrial and cardiac 8-isoprostane levels. Cotreatment with the ZnSO4 supplement alone, PDTC, or ZnSO4+Amlod augmented the rise in cardiomyocyte [Zn2+]i beyond that seen with ALDOST alone, whereas attenuating the rise in [Ca2+]i, which together served to reduce oxidative stress. Thus, a coupled dyshomeostasis of intracellular Ca2+ and Zn2+ was demonstrated in cardiac myocytes and mitochondria during 4-week ALDOST, where prooxidants overwhelm antioxidant defenses. This intrinsically coupled Ca2+ and Zn2+ dyshomeostasis could be uncoupled in favor of antioxidant defenses by selectively increasing free [Zn2+]i and/or reducing [Ca2+]i using cotreatment with ZnSO4 or PDTC alone or ZnSO4+Amlod in combination.

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.

Activation of peripheral blood mononuclear cells and extracellular matrix and inflammatory gene profile in acute myocardial infarction

Inflammation and ECM (extracellular matrix) remodelling play important roles in LV (left ventricular) remodelling following acute MI (myocardial infarction). Previous studies show elevated plasma MMP (matrix metalloproteinase) levels in patients with acute MI, but their sources are not clear. The recruitment of mononuclear cells into the infarcted myocardium is critical for inflammatory responses, but their exact roles in LV remodelling have not been fully investigated, as it is difficult to isolate and study the function of regional inflammatory cells. To address these questions, we isolated PBMCs (peripheral blood mononuclear cells) from blood samples of patients with acute MI or stable angina, or healthy controls (n=14, 8 and 12 respectively). PBMCs were cultured for 24 h and the MMP9 level in the culture medium was measured by gelatin zymography, and MMP9 gene expression was measured by real-time PCR. Two superarrays (ECM and adhesion molecules, and common cytokines; 84 genes included in each array) were employed to screen gene expression profiles by PBMCs in five patients with acute MI and five controls. We found that MMP9 expression by PBMCs at both the mRNA and protein levels was increased 2-fold (both P<0.05) in patients with acute MI compared with the two control groups. Notably, MMP2 was not expressed by PBMCs. Superarray screening revealed that PBMCs not only expressed MMPs, TIMPs (tissue inhibitors of metalloproteinases) and matrix proteins, but also served as an important source of cell adhesion molecules, inflammatory cytokines and growth factors. A total of 42 genes were differentially expressed in patients with acute MI compared with controls. Expression of selected genes was confirmed by real-time PCR. In conclusion, PBMCs constitute a key cellular source for elevated plasma MMP9, but not for MMP2. PBMCs also contribute to systemic and regional inflammation and matrix remodelling in acute MI.

Myocardial remodeling in low-renin hypertension: molecular pathways to cellular injury in relative aldosteronism

The pathologic hypertrophy of hypertensive heart disease is related to the quality, not the quantity, of myocardium; the presence of fibrosis is inevitably linked to structural and functional insufficiencies with increased cardiovascular risk. Elevations in plasma aldosterone that are inappropriate relative to dietary sodium, or relative aldosteronism, are accompanied by suppressed plasma renin activity, elevation in arterial pressure, and dyshomeostasis of divalent cations. The accompanying hypocalcemia, hypomagnesemia, and hypozincemia of aldosteronism contribute to the appearance of secondary hyperparathyroidism. Parathyroid hormone-mediated intracellular calcium overloading of cardiac myocytes and mitochondria leads to the induction of oxidative stress and molecular pathways associated with cardiomyocyte necrosis and scarring of myocardium, whereas the dyshomeostasis of zinc compromises antioxidant defenses. This dys-homeostasis of calcium and zinc, intrinsically coupling prooxidant calcium and antioxidant zinc, raises the prospect for therapeutic strategies designed to mitigate intracellular calcium overloading while enhancing zinc-mediated antioxidant defenses, thus preventing adverse myocardial remodeling with fibrosis, associated diastolic dysfunction, and cardiac arrhythmias.

Aldosterone and the cardiovascular system: a dangerous association

Initial studies have focussed on the actions of aldosterone in renal electrolyte handling and, as a consequence, blood pressure control. More recently, attention has primarily been focussed on its actions on the heart and vascular system, where it is locally produced. Aldosterone by binding mineralocorticoid receptors causes oxidative stress, fibrosis and triggers an inflammatory response in the cardiovascular system. All these effects could be underlying the role of aldo-sterone on cardiac and vascular remodelling associated with different pathological situations. At the vascular level, aldo-sterone affects endothelial function because administration of aldosterone to rats impaired endothelium-dependent relaxations. In addition, the administration of mineralocorticoid receptor antagonists ameliorates endothelium-dependent relaxation in models of both hypertension and atherosclerosis, and in patients with heart failure. Several mechanisms can participate in this effect, including production of vasoconstrictor factors and a reduction in nitric oxide levels. This reduction can involve both a decrease in its production as well as an increase in its degradation by reactive oxygen species. Aldosterone can produce oxidative stress by the activation of transcription factors such as the NF-κB system, which can also trigger an inflammatory process through the production of different cytokines. At cardiac level, high levels of aldosterone can also adversely impact heart function by producing cardiac hypertrophy, diastolic dysfunction and electrical remodelling through changes in ionic channels. All these effects can explain the beneficial effect of mineralocorticoid blockade in the cardiovascular system.

Temporal responses to intrinsically coupled calcium and zinc dyshomeostasis in cardiac myocytes and mitochondria during aldosteronism

Intracellular Ca(2+) overloading, coupled to induction of oxidative stress, is present at 4-wk aldosterone/salt treatment (ALDOST). This prooxidant reaction in cardiac myocytes and mitochondria accounts for necrotic cell death and subsequent myocardial scarring. It is intrinsically linked to increased intracellular zinc concentration ([Zn(2+)](i)) serving as an antioxidant. Herein, we addressed the temporal responses in coupled Ca(2+) and Zn(2+) dyshomeostasis, reflecting the prooxidant-antioxidant equilibrium, by examining preclinical (week 1) and pathological (week 4) stages of ALDOST to determine whether endogenous antioxidant defenses would be ultimately overwhelmed to account for this delay in cardiac remodeling. We compared responses in cardiomyocyte free [Ca(2+)](i) and [Zn(2+)](i) and mitochondrial total [Ca(2+)](m) and [Zn(2+)](m), together with biomarkers of oxidative stress and antioxidant defenses, during 1- and 4-wk ALDOST. At week 1 and compared with controls, we found: 1) elevations in [Ca(2+)](i) and [Ca(2+)](m) were coupled with [Zn(2+)](i) and [Zn(2+)](m); 2) increased mitochondrial H(2)O(2) production, cardiomyocyte xanthine oxidase activity, and cardiac and mitochondrial 8-isoprostane levels, counterbalanced by increased activity of antioxidant proteins, enzymes, and the nonenzymatic antioxidants that can be considered as cumulative antioxidant capacity; some of these enzymes and proteins (e.g., metallothionein-1, Cu/Zn-superoxide, glutathione synthase) are regulated by metal-responsive transcription factor-1; and 3) although these augmented antioxidant defenses were sustained at week 4, they fell short in combating the persistent intracellular Ca(2+) overloading and marked rise in cardiac tissue 8-isoprostane and mitochondrial transition pore opening. Thus a coupled Ca(2+) and Zn(2+) dyshomeostasis occurs early during ALDOST in cardiac myocytes and mitochondria that regulate redox equilibrium until week 4 when ongoing intracellular Ca(2+) overloading and prooxidants overwhelm antioxidant defenses.

Aldosterone-induced endothelial dysfunction of rat aorta: role of poly(ADP-ribose) activation

Introduction. The aim of this study was to investigate whether activation of the nuclear enzyme poly(ADP-ribose) polymerase (PARP) contributes to the development of aldosterone-induced endothelial dysfunction and treatment with the potent PARP inhibitor 1,5-isoquinolinediol (3 mg/kg/day, i.p.) could prevent endothelial dysfunction caused by aldosterone.

Methods. Infusion of subpressor doses of aldosterone with subcutaneously implanted mini-osmotic pumps (0.05 mg/kg/day) to rats for 21 days induced the development of endothelial dysfunction. In order to evaluate endothelial function, isometric tension studies were performed in response to acetylcholine and sodium nitroprusside.Additionally, PAR (the end product of activated PARP) and PARP-1 expressions in the endothelium of thoracic aortas were evaluated by immunohistochemistry.

Results. There was a significant loss of endothelium-dependent vasodilatation in response to acetylcholine in aldosterone-infused rats. In animals treated with 1,5-isoquinolinediol, the effect of aldosterone on vascular responsiveness was less than the untreated groups. Immunohistochemical studies demonstrated that aldosterone administration increased PAR and PARP-1 expressions in the endothelium of thoracic aortas, whereas PARP inhibition decreased their expressions to control levels.

Conclusion. Our results indicate that PARP activation in the vascular system may be a contributory factor to the impaired endothelial function associated with aldosterone administration.

Coupled calcium and zinc dyshomeostasis and oxidative stress in cardiac myocytes and mitochondria of rats with chronic aldosteronism

A dyshomeostasis of extra- and intracellular Ca(2+) and Zn(2+) occurs in rats receiving chronic aldosterone/salt treatment (ALDOST). Herein, we hypothesized that the dyshomeostasis of intracellular Ca(2+) and Zn(2+) is intrinsically coupled that alters the redox state of cardiac myocytes and mitochondria, with Ca(2+) serving as a pro-oxidant and Zn(2+) as an antioxidant. Toward this end, we harvested hearts from rats receiving 4 weeks of ALDOST alone or cotreatment with either spironolactone (Spiro), an aldosterone receptor antagonist, or amlodipine (Amlod), an L-type Ca(2+) channel blocker, and from age/sex-matched untreated controls. In each group, we monitored cardiomyocyte [Ca(2+)]i and [Zn(2+)]i and mitochondrial [Ca(2+)]m and [Zn(2+)]m; biomarkers of oxidative stress and antioxidant defenses; expression of Zn transporters, Zip1 and ZnT-1; metallothionein-1, a Zn(2+)-binding protein; and metal response element transcription factor-1, a [Zn(2+)]i sensor and regulator of antioxidant defenses. Compared with controls, at 4-week ALDOST, we found the following: (a) increased [Ca(2+)]i and [Zn(2+)]i, together with increased [Ca(2+)]m and [Zn(2+)]m, each of which could be prevented by Spiro and attenuated with Amlod; (b) increased levels of 3-nitrotyrosine and 4-hydroxy-2-nonenal in cardiomyocytes, together with increased H(2)O(2) production, malondialdehyde, and oxidized glutathione in mitochondria that were coincident with increased activities of Cu/Zn superoxide dismutase and glutathione peroxidase; and (c) increased expression of metallothionein-1, Zip1 and ZnT-1, and metal response element transcription factor-1, attenuated by Spiro. Thus, an intrinsically coupled dyshomeostasis of intracellular Ca(2+) and Zn(2+) occurs in cardiac myocytes and mitochondria in rats receiving ALDOST, where it serves to alter their redox state through a respective induction of oxidative stress and generation of antioxidant defenses. The importance of therapeutic strategies that can uncouple these two divalent cations and modulate their ratio in favor of sustained antioxidant defenses is therefore suggested.

Nutrient dyshomeostasis in congestive heart failure

The clinical syndrome congestive heart failure (CHF) has its origins rooted in a salt-avid state mediated largely by effector hormones of the renin-angiotensin-aldosterone system. In recent years, this cardiorenal perspective of CHF has taken on a broader perspective. One which focuses on a progressive systemic illness, whose major features include the presence of oxidative stress in diverse tissues and elevated circulating levels of proinflammatory cytokines coupled with a wasting of soft tissues and bone. Experimental studies, which simulate chronic renin-angiotensin-aldosterone system activation, and translational studies in patients with salt avidity having decompensated biventricular failure with hepatic and splanchnic congestion have forged a broader understanding of this illness and the important contribution of a dyshomeostasis of Ca2+, Mg2+, Zn2+, Se2+, and vitamins D, B12, and B1. Herein, we review biomarkers indicative of the nutrient imbalance found in CHF and raise the question of a need for a polynutrient supplement in the overall management of CHF.

Aldosterone blockade by Spironolactone improves the hypertensive vascular hypertrophy and remodeling in angiotensin II overproducing transgenic mice

OBJECTIVES AND BACKGROUND

Recent evidence has revealed that aldosterone (ALDO) is produced in the vasculature, and acts directly in the cardiovascular system. This study was designed to examine the role of ALDO in the process of long-term renin-angiotensin system (RAS) induced vascular remodeling.

MATERIAL AND METHOD

Hypertensive transgenic mice that overproduce angiotensin II (AngII), i.e., Tsukuba-Hypertensive-Mice (THM), were given tap water or 1% salt water and treated with or without Spironolactone (SPRL: 20mg/kg/day) for 4 weeks. We also employed A7r5 cells and investigated the effect of SPRL on the AngII mediated signal transduction in the vascular smooth muscle cells.

RESULTS

Intimal hyperplasia, medial hypertrophy and degradation of medial elastic laminae were observed in the abdominal aorta, independent of blood pressure. Taking 1% salt water markedly enhanced these changes. In contrast, SPRL-treated THM showed almost complete disappearance of these intimal hyperplasia and medial hypertrophy. Osteopontin (OPN) was markedly up-regulated in the intima and media. However, it was inhibited by SPRL treatment in spite of high level of AngII. In A7r5 cells, AngII (10(-7)muM) induced OPN expression and pretreatment with MEK, PI3K, and EGFR inhibitor suppressed it. SPRL pretreatment also inhibited AngII-induced ERK and AKT phosphorylation, and resulted in the suppression of AngII-induced OPN expression.

CONCLUSIONS

ALDO blockade by SPRL restores the vascular remodeling caused by the long-term RAS enhancement even in the high level of AngII, independent of blood pressure. Blocking AngII alone may not be sufficient, and direct ALDO blockade is also important to prevent vascular disease.