Claudio de Lucia

Negative Impact of β-Arrestin-1 on Post-Myocardial Infarction Heart Failure via Cardiac and Adrenal-Dependent Neurohormonal Mechanisms

&bgr;-Arrestin (&bgr;arr)-1 and &bgr;-arrestin-2 (&bgr;arrs) are universal G-protein–coupled receptor adapter proteins that negatively regulate cardiac &bgr;-adrenergic receptor (&bgr;AR) function via &bgr;AR desensitization and downregulation. In addition, they mediate G-protein–independent &bgr;AR signaling, which might be beneficial, for example, antiapoptotic, for the heart. However, the specific role(s) of each &bgr;arr isoform in cardiac &bgr;AR dysfunction, the molecular hallmark of chronic heart failure (HF), remains unknown. Furthermore, adrenal &bgr;arr1 exacerbates HF by chronically enhancing adrenal production and hence circulating levels of aldosterone and catecholamines. Herein, we sought to delineate specific roles of &bgr;arr1 in post–myocardial infarction (MI) HF by testing the effects of &bgr;arr1 genetic deletion on normal and post-MI cardiac function and morphology. We studied &bgr;arr1 knockout (&bgr;arr1KO) mice alongside wild-type controls under normal conditions and after surgical MI. Normal (sham-operated) &bgr;arr1KO mice display enhanced &bgr;AR-dependent contractility and post-MI &bgr;arr1KO mice enhanced overall cardiac function (and &bgr;AR-dependent contractility) compared with wild type. Post-MI &bgr;arr1KO mice also show increased survival and decreased cardiac infarct size, apoptosis, and adverse remodeling, as well as circulating catecholamines and aldosterone, compared with post-MI wild type. The underlying mechanisms, on one hand, improved cardiac &bgr;AR signaling and function, as evidenced by increased &bgr;AR density and procontractile signaling, via reduced cardiac &bgr;AR desensitization because of cardiac &bgr;arr1 absence, and, on the other hand, decreased production leading to lower circulating levels of catecholamines and aldosterone because of adrenal &bgr;arr1 absence. Thus, &bgr;arr1, via both cardiac and adrenal effects, is detrimental for cardiac structure and function and significantly exacerbates post-MI HF.

Targeting the β-Adrenergic Receptor System Through G-Protein–Coupled Receptor Kinase 2: A New Paradigm for Therapy and Prognostic Evaluation in Heart Failure From Bench to Bedside

G-protein–coupled receptors (GPCRs) are a superfamily of more than 1000 membrane proteins that respond to a wide spectrum of extracellular signals, modulating various physiopathological processes.1,2 Several GPCRs, such as adrenergic, angiotensin, endothelin, and adenosine receptors, are expressed in cardiovascular (CV) tissues to maintain CV homeostasis. Importantly, GPCR-mediated adrenergic deregulation has been shown to both cause and contribute to the onset and progression of major CV diseases ultimately leading to heart failure (HF). Thus, GPCRs have become salient targets of current pharmacotherapy in CV disorders, and in past decades, many efforts have been made to better clarify their role in the pathophysiology of cardiac disease, focusing not only on receptor functions but also on postreceptor components that mediate or regulate their responses. Among the latter, a relevant role has been attributed to G-protein–coupled receptor kinases (GRKs). In this review, we focus on GRK2, the most abundant and versatile GRK expressed on CV system, tracing the way from initial experimental evidence to more recent data suggesting a potential role for this kinase in the clinical management of HF.1,2 ### GPCR Signaling and GRK Functions: Pathophysiological Background On stimulation, GPCRs interact with heterotrimeric G proteins, which in turn dissociate into 2 functional monomers, namely Gα and Gβγ, both of which modulate different effector systems. Agonist binding to GPCR promotes the activation of complex regulatory mechanisms to protect the receptor from both acute and chronic stimulation, a process termed desensitization. As extensively described, GPCR desensitization involves 3 main events in chronological order: receptor phosphorylation and uncoupling from G proteins, internalization of membrane-bound receptors, and downregulation through reduced mRNA and protein synthesis or increased degradation of internalized receptors.1,2 The desensitization process is mediated by 3 families of proteins: second-messenger–dependent protein kinases, GRKs and arrestins. The defining feature of GRKs is that …

Oral Anticoagulation Therapy in Heart Failure Patients in Sinus Rhythm: A Systematic Review and Meta-Analysis

Background Heart failure (HF) patients show high morbidity and mortality rate with increased risk of malignant arrhythmia and thromboembolism. Anticoagulation reduces embolic event and death rates in HF patients with atrial fibrillation, but if antithrombotic therapy is beneficial in patients with HF in sinus rhythm is still debated. Methodology and Principal Findings We conducted a systematic review of prospective, randomized controlled trials (RCTs) to assess the efficacy and safety of oral anticoagulant therapies (OATs) compared to antiplatelet treatment in HF patients in sinus rhythm. MEDLINE, Web of Science, CENTRAL and Scopus databases were searched up to May 2012. Four RCTs were identified and a total of 3663 patients were included in the meta-analysis. Patients with both ischemic and non-ischemic HF were included. There was no significant difference in mortality (odds ratio (OR) 1.01, 95% confidence interval (CI) 0.86 to 1.19) between OATs group and antiplatelet drug group. OATs have reduced ischemic stroke risk (OR 0.49, 95% CI 0.32 to 0.74), but have increased major bleeding risk (OR 2.01, 95% CI 1.40 to 2.88) compared to antiplatelet treatment. Conclusion In HF patients in sinus rhythm OATs do not show a better risk-benefit profile compared to antiplatelet treatment in cardioembolism prevention. Warfarin and aspirin seem to be similar in reducing mortality. Warfarin reduces the incidence of ischemic stroke, but increases major bleedings. Thus, it is possible to speculate that aspirin prescription be indicated in patients with high risk of bleeding, whereas warfarin could be preferred in patients with high thromboembolic risk.

Autonomic dysfunction in Alzheimer's disease: tools for assessment and review of the literature.

Autonomic dysfunction is very common in patients with dementia, and its presence might also help in differential diagnosis among dementia subtypes. Various central nervous system structures affected in Alzheimers disease are also implicated in autonomic nervous system regulation, and it has been hypothesized that the deficit in central cholinergic function observed in Alzheimers disease could likely lead to autonomic dysfunction. Several feasible tests can be used in clinical practice for the assessment of parasympathetic and sympathetic functions, especially in terms of cardiovascular autonomic modulation. In this review, we describe the different tests available and the evidence from the literature which indicate a definite presence of autonomic dysfunction in dementia at various degrees. Importantly, the recognition of dysautonomia, besides possibly being an early marker of dementia, would help prevent the disabling complications which increase the risk of morbidity, institutionalization, and mortality in these individuals.

Vascular Endothelial Growth Factor Blockade Prevents the Beneficial Effects of β-Blocker Therapy on Cardiac Function, Angiogenesis, and Remodeling in Heart Failure

Background—Impaired angiogenesis in the post-myocardial infarction heart contributes to the progression to heart failure. The inhibition of vascular endothelial growth factor (VEGF) signaling has been shown to be crucial for the transition from compensatory hypertrophy to cardiac failure. Importantly, &bgr;-adrenergic receptor blocker therapy has been also shown to improve myocardial perfusion by enhancing neoangiogenesis in the failing heart. Methods and Results—Eight weeks from surgically induced myocardial infarction, heart failure rats were randomized to receive bisoprolol (B) or vehicle. At the end of a 10-week treatment period, echocardiography revealed reduced cardiac diameters and improved cardiac function in B-treated compared with vehicle-treated rats. Moreover, B treatment was associated with increased cardiac angiogenesis and in vivo coronary perfusion and reduced cardiac fibrosis. Importantly, 2 weeks after B treatment was started, increased cardiac VEGF expression and Akt and endothelial NO synthase activation were observed by comparing B-treated with drug-untreated failing hearts. To test whether the proangiogenic effects of B act via activation of VEGF pathway, rats were intravenously injected with adenoviral vector encoding a decoy VEGF receptor (Ad-Flk) or a control adenovirus (Ad-C), at the start of the treatment with B. After 10 weeks, histological analysis revealed reduced capillary and coronary perfusion in B-treated plus Ad-Flk rats compared with B-treated plus Ad-C rats. Moreover, VEGF inhibition counteracted the positive effects of B on cardiac function and remodeling. Conclusions—&bgr;-Blockade promotes cardiac angiogenesis in heart failure via activation of VEGF signaling pathway. &bgr;-Blocker–induced enhancement of cardiac angiogenesis is essential for the favorable effects of this therapy on cardiac function and remodeling.

GRK2 blockade with βARKct is essential for cardiac β2-adrenergic receptor signaling towards increased contractility

Backgroundβ1- and β2–adrenergic receptors (ARs) play distinct roles in the heart, e.g. β1AR is pro-contractile and pro-apoptotic but β2AR anti-apoptotic and only weakly pro-contractile. G protein coupled receptor kinase (GRK)-2 desensitizes and opposes βAR pro-contractile signaling by phosphorylating the receptor and inducing beta-arrestin (βarr) binding. We posited herein that GRK2 blockade might enhance the pro-contractile signaling of the β2AR subtype in the heart. We tested the effects of cardiac-targeted GRK2 inhibition in vivo exclusively on β2AR signaling under normal conditions and in heart failure (HF).ResultsWe crossed β1AR knockout (B1KO) mice with cardiac-specific transgenic mice expressing the βARKct, a known GRK2 inhibitor, and studied the offspring under normal conditions and in post-myocardial infarction (MI). βARKct expression in vivo proved essential for β2AR-dependent contractile function, as β2AR stimulation with isoproterenol fails to increase contractility in either healthy or post-MI B1KO mice and it only does so in the presence of βARKct. The main underlying mechanism for this is blockade of the interaction of phosphodiesterase (PDE) type 4D with the cardiac β2AR, which is normally mediated by the actions of GRK2 and βarrs on the receptor. The molecular “brake” that PDE4D poses on β2AR signaling to contractility stimulation is thus “released”. Regarding the other beneficial functions of cardiac β2AR, βARKct increased overall survival of the post-MI B1KO mice progressing to HF, via a decrease in cardiac apoptosis and an increase in wound healing-associated inflammation early (at 24 hrs) post-MI. However, these effects disappear by 4 weeks post-MI, and, in their place, upregulation of the other major GRK in the heart, GRK5, is observed.ConclusionsGRK2 inhibition in vivo with βARKct is absolutely essential for cardiac β2AR pro-contractile signaling and function. In addition, β2AR anti-apoptotic signaling in post-MI HF is augmented by βARKct, although this effect is short-lived.

Adrenal adrenoceptors in heart failure

Heart failure (HF) is a chronic clinical syndrome characterized by the reduction in left ventricular (LV) function and it represents one of the most important causes of morbidity and mortality worldwide. Despite considerable advances in pharmacological treatment, HF represents a severe clinical and social burden. Sympathetic outflow, characterized by increased circulating catecholamines (CA) biosynthesis and secretion, is peculiar in HF and sympatholytic treatments (as β-blockers) are presently being used for the treatment of this disease. Adrenal gland secretes Epinephrine (80%) and Norepinephrine (20%) in response to acetylcholine stimulation of nicotinic cholinergic receptors on the chromaffin cell membranes. This process is regulated by adrenergic receptors (ARs): α2ARs inhibit CA release through coupling to inhibitory Gi-proteins, and β ARs (mainly β2ARs) stimulate CA release through coupling to stimulatory Gs-proteins. All ARs are G-protein-coupled receptors (GPCRs) and GPCR kinases (GRKs) regulate their signaling and function. Adrenal GRK2-mediated α2AR desensitization and downregulation are increased in HF and seem to be a fundamental regulator of CA secretion from the adrenal gland. Consequently, restoration of adrenal α2AR signaling through the inhibition of GRK2 is a fascinating sympatholytic therapeutic strategy for chronic HF. This strategy could have several significant advantages over existing HF pharmacotherapies minimizing side-effects on extra-cardiac tissues and reducing the chronic activation of the renin–angiotensin–aldosterone and endothelin systems. The role of adrenal ARs in regulation of sympathetic hyperactivity opens interesting perspectives in understanding HF pathophysiology and in the identification of new therapeutic targets.

β-adrenergic receptors and g protein-coupled receptor Kinase-2 in Alzheimer's disease: A new paradigm for prognosis and therapy?

Alzheimers disease (AD) is a devastating form of dementia that imposes a severe burden on health systems and society. Although several aspects of AD pathogenesis have been elucidated over the last few decades, many questions still need to be addressed. In fact, currently available medications only provide symptomatic improvement in patients with AD without affecting disease progression. The β-adrenergic receptor (β-AR) system can be considered a possible target that deserves further exploration in AD. The central noradrenergic system undergoes substantial changes in the course of AD and β-ARs have been implicated not only in amyloid formation in AD brain but also in amyloid-induced neurotoxicity. Moreover, clinical evidence suggests a protective role of β-AR blockers on AD onset. In addition to that, post-receptor components of β-AR signaling seem to have a role in AD pathogenesis. In particular, the G protein coupled receptor kinase 2, responsible for β-AR desensitization and downregulation, mediates amyloid-induced β-AR dysfunction in neurons, and its levels in circulating lymphocytes of AD patients are increased and inversely correlated with patients cognitive status. Therefore, there is an urgent need to gain further insight on the role of the adrenergic system components in AD pathogenesis in order to translate preclinical and clinical knowledge to more efficacious prognostic and therapeutic strategies.

Targeting the β-Adrenergic Receptor System Through G-Protein–Coupled Receptor Kinase 2: A New Paradigm for Therapy and Prognostic Evaluation in Heart Failure

G-protein–coupled receptors (GPCRs) are a superfamily of more than 1000 membrane proteins that respond to a wide spectrum of extracellular signals, modulating various physiopathological processes.1,2 Several GPCRs, such as adrenergic, angiotensin, endothelin, and adenosine receptors, are expressed in cardiovascular (CV) tissues to maintain CV homeostasis. Importantly, GPCR-mediated adrenergic deregulation has been shown to both cause and contribute to the onset and progression of major CV diseases ultimately leading to heart failure (HF). Thus, GPCRs have become salient targets of current pharmacotherapy in CV disorders, and in past decades, many efforts have been made to better clarify their role in the pathophysiology of cardiac disease, focusing not only on receptor functions but also on postreceptor components that mediate or regulate their responses. Among the latter, a relevant role has been attributed to G-protein–coupled receptor kinases (GRKs). In this review, we focus on GRK2, the most abundant and versatile GRK expressed on CV system, tracing the way from initial experimental evidence to more recent data suggesting a potential role for this kinase in the clinical management of HF.1,2 ### GPCR Signaling and GRK Functions: Pathophysiological Background On stimulation, GPCRs interact with heterotrimeric G proteins, which in turn dissociate into 2 functional monomers, namely Gα and Gβγ, both of which modulate different effector systems. Agonist binding to GPCR promotes the activation of complex regulatory mechanisms to protect the receptor from both acute and chronic stimulation, a process termed desensitization. As extensively described, GPCR desensitization involves 3 main events in chronological order: receptor phosphorylation and uncoupling from G proteins, internalization of membrane-bound receptors, and downregulation through reduced mRNA and protein synthesis or increased degradation of internalized receptors.1,2 The desensitization process is mediated by 3 families of proteins: second-messenger–dependent protein kinases, GRKs and arrestins. The defining feature of GRKs is that …

Instruments for geriatric assessment: new multidimensional assessment approaches

During the last century the considerable increase in life expectancy has led to important demographic changes and, consequently, to new clinical scenarios. Nowadays, chronic conditions, comorbidities and socio-economic factors constitute a relevant health management issue. In particular, the definition of frail elderly individuals has proven to have a strong role in the identification of high-risk patients, their clinical management and prognosis. Reorganization of the medical system has been associated with the development of new instruments for clinical assessment, focused on clinical and socio-economic issues, resulting in a multidimensional geriatric assessment. A large number of approaches have been validated in different clinical settings and populations, until the development of multidimensional instruments demonstrated to have a crucial role in the identification of frail individuals and in their clinical management. Interestingly, some of these, such as the Multidimensional Prognostic Index (MPI), proved to play a relevant role in mortality risk stratification even in particular clinical settings such as chronic kidney disease.