Aldosterone as a cardiovascular risk hormone

The pathophysiological role of aldosterone in the development of cardiovascular disease has long been considered to be due its potent volume expansion/hypertensive effect mainly via mineralocorticoid receptor (MR) expressed in renal tubular epithelial cells. However, recent accumulating lines of evidence from clinical and experimental studies have suggested that direct cardiovascular effect of aldosterone contributes to the development of cardiovascular injury via MRs in non-epithelial tissue. A series of recent clinical studies have revealed that patients with primary aldosteronism have higher incidence of cardiovascular and renal complications than those with essential hypertension, and that aldosterone antagonism has cardiovascular protective effect in patients with heart failure independent from blood pressure. Numerous experimental studies have shown that both inflammation and oxidative stress play an initial and key role in the development of aldosterone-induced cardiovascular injury via non-epithelial MR activation. In this review, we discuss recent research progress in aldosterone and MR effects, with special emphasis on the pathophysiological role of aldosterone in cardiovascular diseases and the possible molecular mechanism(s) of cardiovascular injury by non-epithelial MR activation.     

Aldosterone as a cardiovascular risk factor.

Aldosterone exerts cardiovascular effects by influencing epithelial fluid and electrolyte excretion, and thus blood volume and pressure. Mineralocorticoid receptors (MR) are found in epithelial and non-epithelial tissues (vessel walls, heart, brain), with high affinity for aldosterone and physiological glucocorticoids cortisol and corticosterone. MR blockade by spironolactone or eplerenone favorably affects cardiovascular outcomes. In some situations (primary aldosteronism, experimental mineralocorticoid administration) activation of cardiovascular MR reflects aldosterone levels inappropriate for salt status. In others (heart failure, essential hypertension) aldosterone and Na(+) status are often normal pretreatment; cardiovascular MR may thus be activated by normal glucocorticoid levels after tissue damage and reactive oxygen species generation. Therefore, although unilateral adrenalectomy is preferred therapy for unilateral aldosterone-producing adenoma or hyperplasia, MR blockade may be useful in cardiovascular diseases where aldosterone levels are normal.     

Aldosterone as a mediator in cardiovascular injury

The renin-angiotensin-aldosterone system plays a central role in the development of hypertension and the progression of end-organ damage. Although angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists can initially suppress plasma aldosterone, it is now well established that aldosterone escape may occur, whereby aldosterone levels return to or exceed baseline levels. The classic effects of aldosterone relate mainly to its action on epithelial cells to regulate water and electrolyte balance. However, blood pressure reduction or fluid loss could not account for the results of the Randomized Aldactone Evaluation Study, which showed that a low dose of spironolactone in addition to conventional therapy could decrease the overall risk of mortality by 30% among patients with severe congestive heart failure. The action of aldosterone at nonepithelial sites in the brain, heart, and vasculature is consistent with the presence of mineralocorticoid receptors in these tissues. Aldosterone has a number of deleterious effects on the cardiovascular system, including myocardial necrosis and fibrosis, vascular stiffening and injury, reduced fibrinolysis, endothelial dysfunction, catecholamine release, and production of cardiac arrhythmias. Several studies have now shown vascular and target-organ protective effects of aldosterone receptor antagonism in the absence of significant blood pressure lowering, consistent with a major role for endogenous mineralocorticoids as mediators of cardiovascular injury. The advent of selective aldosterone receptor antagonists such as eplerenone should prove of great therapeutic value in the prevention of cardiovascular disease and associated end-organ damage.     

Emerging therapeutic options for the management of hepatitis C infection

Until recently the traditional treatment for hepatitis C infection included pegylated interferon and ribavirin combination therapy. The sustained virological response (SVR) seen with this combination is poor and requires lengthy treatment to achieve. Additionally, significant side effects and numerous contraindications prevented many patients from being successfully treated with this therapy. In 2011, two new protease inhibitors, telaprevir and boceprevir, were approved for use with pegylated interferon and ribavirin in the United States by the United States Food and Drug Administration. These agents have significantly improved SVR rates; however significant problems with toxicity remain including severe skin rash and neutropenia. There are a wide range of compounds in late stage development for the future treatment of hepatitis C that exploit many different mechanisms of viral inhibition. Some of these compounds include additional protease inhibitors, like telaprevir and boceprevir, as well as inhibitors of other nonstructural proteins in the viral genome such as NS5A and NS5B, and compounds that target host proteins within the virus. Some of these agents are being developed for oral administration once daily and various combinations are being assessed for use without the need for pegylated interferon and ribavirin. This paper reviews agents in late phase development that may be commercially available within 1-2 years.     

Aldosterone and cardiovascular risk

Through its classic effects on sodium and potassium homeostasis, aldosterone, when produced in excess, is associated with the development of hypertension and hence with higher cardiovascular and renal risk. In recent years, experimental and epidemiologic data have suggested that aldosterone also may be linked to high cardiovascular risk independently of its effects on blood pressure. Thus, aldosterone has been associated with obesity and metabolic syndrome in selected populations, and these associations may further contribute to the higher cardiovascular risk of subjects with elevated aldosterone levels. Moreover, aldosterone has been reported to promote inflammation, oxidative stress, and fibrosis in a number of tissues. Clinical evidence indicates that patients with primary hyperaldosteronism have a higher risk of developing cardiovascular and renal complications than patients with essential hypertension who have the same level of blood pressure. Aldosterone receptor blockade has been shown to lower cardiovascular mortality after myocardial infarction and in patients with congestive heart failure. Some studies have also demonstrated that aldosterone blockade could have a favorable impact on the progression of renal disease. However, prospective interventional trials are needed to further evaluate the impact of blockade of aldosterone on cardiovascular risk.     

Functional foods as potential therapeutic options for metabolic syndrome

Obesity as part of metabolic syndrome is a major lifestyle disorder throughout the world. Current drug treatments for obesity produce small and usually unsustainable decreases in body weight with the risk of major adverse effects. Surgery has been the only treatment producing successful long‐term weight loss. As a different but complementary approach, lifestyle modification including the use of functional foods could produce a reliable decrease in obesity with decreased comorbidities. Functional foods may include fruits such as berries, vegetables, fibre‐enriched grains and beverages such as tea and coffee. Although health improvements continue to be reported for these functional foods in rodent studies, further evidence showing the translation of these results into humans is required. Thus, the concept that these fruits and vegetables will act as functional foods in humans to reduce obesity and thereby improve health remains intuitive and possible rather than proven.     

Management of movement disorders in glutaryl-CoA dehydrogenase deficiency: Anticholinergic drugs and botulinum toxin as additional therapeutic options

Glutaric aciduria type I is an inborn error of metabolism due to the deficiency of glutaryl-CoA dehydrogenase, an enzyme responsible for the catabolism of lysine, hydroxylysine and tryptophan. The most important neurological symptoms include dyskinesia and dystonia, which can be focal, segmental or generalized. Treatment of the extrapyramidal syndrome is often unsatisfactory. We report our experience in the treatment of generalized and focal dystonia with anticholinergic drugs and botulinum toxin type A, respectively. Both therapies proved beneficial.     

Homocysteine, endothelial dysfunction and cardiovascular risk: pathomechanisms and therapeutic options

Elevated homocyst(e)ine plasma concentrations are an independent risk factor for cardiovascular disease. Hyperhomocyst(e)inaemia is common in patients with peripheral arterial occlusive disease, coronary heart disease, cerebrovascular disease, carotid artery stenosis and venous thromboembolism. Endothelial dysfunction may be one underlying cause leading to proatherogenic effects associated with hyperhomocyst(e)inaemia. However, the mechanisms which lead to impaired endothelial function in hyperhomocyst(e)inaemia are not fully understood. Recent evidence suggests that homocyst(e)ine may interact with physiological mediators of the endothelial matrix. Oxidative mechanisms and decreased biological activity of endothelium-derived nitric oxide (NO) may also contribute to homocyst(e)ine-associated endothelial dysfunction. B vitamins are essential cofactors in the metabolism of homocyst(e)ine to methionine via the remethylation-pathway (vitamin B12, folic acid) and to cystathionine via the transsulphuration-pathway (vitamin B6). Dietary deficiencies of folic acid, vitamin B12, and vitamin B6 appear to be common among elderly people in the western world and represent one pathogenic factor related to the incidence of hyperhomocyst(e)inaemia. Several studies have demonstrated that dietary supplementation with folic acid and the vitamins B12 and B6 is an efficient means to decrease plasma homocyst(e)ine. No clinical studies are available to date to prove whether reducing homocyst(e)ine levels to the normal range by supplementary B vitamins will also beneficially affect vascular function or cardiovascular risk. Furthermore it is unknown whether moderately elevated homocyst(e)ine concentrations per se may predispose to development of vascular disease, or whether homocyst(e)ine is an indirect marker of cardiovascular disease. Further investigations will be necessary to elucidate the causal relationship between elevated homocyst(e)ine plasma concentrations and the incidence of cardiovascular events, especially since the therapeutic strategies in hyperhomocyst(e)inaemia would differ depending on the underlying pathophysiological mechanisms.     

Aldosterone and parathyroid hormone interactions as mediators of metabolic and cardiovascular disease

Inappropriate aldosterone and parathyroid hormone (PTH) secretion is strongly linked with development and progression of cardiovascular (CV) disease. Accumulating evidence suggests a bidirectional interplay between parathyroid hormone and aldosterone. This interaction may lead to a disproportionally increased risk of CV damage, metabolic and bone diseases.     

Sauna as a therapeutic option for cardiovascular disease

The physiologic effect of the sauna in human beings has been studied extensively, but only recently have there been studies to suggest sauna can be an effective therapeutic modality for patients with cardiovascular disease, especially for those with congestive heart failure. The data reported to date have been promising, but definitive studies are not possible because sauna treatment would be difficult to evaluate in a double-blind, placebo-controlled study.     

Beyond bulevirtide: Alternative therapeutic options for the management of hepatitis delta virus

Hepatitis delta virus (HDV) is a small RNA virus which needs Hepatitis B Surface Antigen for its envelope, for entry into hepatocytes and secretion. HDV chronic infection affects around 12 million people worldwide. HDV infection is believed to be the most severe form of viral hepatitis, with a high risk of developing cirrhosis and hepatocellular carcinoma. Pegylated interferons has been used and recommended by guidelines, although not approved, with low efficacy and poor tolerability. Bulevirtide (entry inhibitor) has been recently conditionally approved by the European Medicines Agency. These treatments have many advantages, but they have also limitations since there are non-responders to these previous therapies. There is an urgent need to develop new drugs. In this article, we review antiviral treatments under development for HDV chronic infection (except bulevirtide reviewed in a specific article), including those in the HBV cure programme, outlining their respective mechanisms-of-action.     

Diagnostic and therapeutic options in the management of nonvariceal upper gastrointestinal bleeding

Upper gastrointestinal bleeding from peptic ulcers is common. Advances in prognostication, therapeutic endoscopy, and medical management have evolved rapidly. Patients most likely to rebleed after therapy can now be identified and monitored more closely, and patients with ulcers of low risk for rebleeding can be managed on an outpatient basis. High-risk patients include those with ulcers containing a visible vessel or who are actively bleeding. Endoscopic therapy is mandatory in high-risk patients and involves at least two hemostatic techniques. Second-look endoscopy and repeated hemostasis should be performed promptly in patients who rebleed. Adjunctive treatment includes intravenous proton pump inhibitor administered in high doses for the first 72 hours after endoscopic therapy. Further studies are needed to determine the optimal combination of hemostatic techniques to better target patients who are at risk for ulcer rebleeding.     

New therapeutic options for acromegaly

Acromegaly is a slowly developing disfiguring disease characterized by chronic growth hormone (GH) and insulin-like growth factor-I (IGF-I) excess and caused by a pituitary somatotroph adenoma. It is associated to 2- to 3 fold increased mortality, compared to normal population, mostly due to cardiovascular and cerebro-vascular diseases, and to several co-morbid systemic illnesses, such as diabetes mellitus, hypertension, severe arthropathies, a specific cardio-myopathy, goitre, sleep-apnoea, intractable headache. The morbidity and excess mortality of acromegaly are usually the consequence of the metabolic actions of excess GH and IGF-I secretion, while only in rare patients mortality is due to the mass effects of the pituitary tumour. Since, serum IGF-I concentrations within age-adjusted normal range, and a tight GH control have to be achieved to normalize life-expectancy in these patients, an aggressive, and often multi-modality treatment is required for acromegaly. In recent years, new drugs, and new formulations of old drugs, have been developed that are able to effectively inhibit GH secretion or GH action, and may represent important adjuncts or even alternatives to the traditional approaches of surgery and radiotherapy. This review briefly summarizes the therapeutic options nowadays available for acromegaly. A brief note about innovative drugs under study, is also given.     

Novel therapeutic options for osteoporosis

Osteoporosis remains a significant clinical problem despite effective therapies. Many patients cannot or will not take currently available therapies. For this reason, research continues in search of more effective and more tolerable agents. Arzoxifene and TSE-424 are investigational selective estrogen receptor modulators that have been shown to be effective in animal studies and are now in clinical studies. Tibolone is a tissue-specific steroid that is currently used in Europe for the prevention and treatment of osteoporosis. Multiple studies have shown efficacy in improving bone mineral density, but no fracture studies have been conducted to date. Although studies of the effect of isoflavones on bone mineral density have been encouraging, a large multicenter study in Europe recently showed no effect of isoflavones on fractures. The investigational bisphosphonates ibandronate and zoledronic acid may offer the advantage of less frequent dosing. The newly described agent osteoprotegerin has been shown in early studies to inhibit bone turnover. Finally, the issue of efficacy of statins in bone continues to be debated with no prospective, randomized studies yet to confirm the suggestion of benefit seen in epidemiologic studies.     

Advanced heart failure: a practical management algorithm and therapeutic options

Despite medical and surgical advances in the management of heart failure, 3%-10% of patients clinically reside in the severe stages of this condition. The management of advanced, end-stage heart failure is one of the major challenges of medicine today. An algorithm applicable to the management of severe heart failure is presented and discussed, with an emphasis on medical treatment and therapeutic options.     

Aldosterone as an Independent Factor in Cerebrovascular Damage

Aldosterone is produced not only in the adrenal gland but also in other tissues, including the brain, where it plays an important role in the control of blood pressure and water and electrolyte homeostasis. Aldosterone has also been demonstrated to be a major factor in target organ damage independent of its effects on blood pressure. Herein we review the pathophysiology of aldosterone action in the brain and the clinical and experimental studies on the detrimental effects of aldosterone in the brain.