Effect of monomeric adiponectin on cardiac function and perfusion in anesthetized pig

Cardiac-to-adipose axis in metabolic homeostasis and diseases: special instructions from the heart

Adipose tissue is essential for maintaining systemic metabolic homeostasis through traditional metabolic regulation, endocrine crosstalk, and extracellular vesicle production. Adipose dysfunction is a risk factor for cardiovascular diseases. The heart is a traditional pump organ. However, it has recently been recognized to coordinate interorgan cross-talk by providing peripheral signals known as cardiokines. These molecules include specific peptides, proteins, microRNAs and novel extracellular vesicle-carried cargoes. Current studies have shown that generalized cardiokine-mediated adipose regulation affects systemic metabolism. Cardiokines regulate lipolysis, adipogenesis, energy expenditure, thermogenesis during cold exposure and adipokine production. Moreover, cardiokines participate in pathological processes such as obesity, diabetes and ischemic heart injury. The underlying mechanisms of the cardiac-to-adipose axis mediated by cardiokines will be further discussed to provide potential therapeutic targets for metabolic diseases and support a new perspective on the need to correct adipose dysfunction after ischemic heart injury.

Aerobic exercise training reduces cardiac function and coronary flow-induced vasodilation in mice lacking adiponectin

We tested the hypothesis that adiponectin deficiency attenuates cardiac and coronary microvascular function and prevents exercise training-induced adaptations of the myocardium and the coronary microvasculature in adult mice. Adult wild-type (WT) or adiponectin knockout (adiponectin KO) mice underwent treadmill exercise training or remained sedentary for 8-10 wk. Systolic and diastolic functions were assessed before and after exercise training or cage confinement. Vasoreactivity of coronary resistance arteries was assessed at the end of exercise training or cage confinement. Before exercise training, ejection fraction and fractional shortening were similar in adiponectin KO and WT mice, but isovolumic contraction time was significantly lengthened in adiponectin KO mice. Exercise training increased ejection fraction (12%) and fractional shortening (20%) with no change in isovolumic contraction time in WT mice. In adiponectin KO mice, both ejection fraction (-9%) and fractional shortening (-12%) were reduced after exercise training and these decreases were coupled to a further increase in isovolumic contraction time (20%). In sedentary mice, endothelium-dependent dilation to flow was higher in arterioles from adiponectin KO mice as compared with WT mice. Exercise training enhanced dilation to flow in WT mice but decreased flow-induced dilation in adiponectin KO mice. These data suggest that compensatory mechanisms contribute to the maintenance of cardiac and coronary microvascular function in sedentary mice lacking adiponectin; however, in the absence of adiponectin, cardiac and coronary microvascular adaptations to exercise training are compromised.NEW & NOTEWORTHY We report that compensatory mechanisms contribute to the maintenance of cardiac and coronary microvascular function in sedentary mice in which adiponectin has been deleted; however, when mice lacking adiponectin are subjected to the physiological stress of exercise training, beneficial coronary microvascular and cardiac adaptations are compromised or absent.

Can Adiponectin Help us to Target Diastolic Dysfunction?

Adiponectin is the most abundant adipokine and exhibits anti-inflammatory, antiatherogenic and antidiabetic properties. Unlike other adipokines, it inversely correlates with body weight and obesity-linked cardiovascular complications. Diastolic dysfunction is the main mechanism responsible for approximately half of all heart failure cases, the so-called heart failure with preserved ejection fraction (HFpEF), but therapeutic strategies specifically directed towards these patients are still lacking. In the last years, a link between adiponectin and diastolic dysfunction has been suggested. There are several mechanisms through which adiponectin may prevent most of the pathophysiologic mechanisms underlying diastolic dysfunction and HFpEF, including the prevention of myocardial hypertrophy, cardiac fibrosis, nitrative and oxidative stress, atherosclerosis and inflammation, while promoting angiogenesis. Thus, understanding the mechanisms underlying adiponectin-mediated improvement of diastolic function has become an exciting field of research, making adiponectin a promising therapeutic target. In this review, we explore the relevance of adiponectin signaling for the prevention of diastolic dysfunction and identify prospective therapeutic targets aiming at the treatment of this clinical condition.

Effects of lifestyle intervention on left ventricular regional myocardial function in metabolic syndrome patients from the RESOLVE randomized trial

AIMS

The purpose of our study was to determine the effect of lifestyle intervention on left ventricular (LV) regional myocardial function in patients with metabolic syndrome (MetS) and investigate the relationships of the changes in myocardial function to changes in epicardial adipose tissue (EAT), inflammatory profile and MetS components.

METHODS

Eighty-seven MetS patients were enrolled in a 6month lifestyle intervention program based on dietary management and increased physical activity, and compared with 44 aged and sex-matched healthy controls. MetS individuals were allocated to different groups randomized (computer-generated randomization) on exercise modalities (high-intensity dominant resistance or aerobic training, and moderate-intensity of both modes). EAT was measured by transthoracic echocardiography and LV longitudinal strains and strain rates were obtained using vector velocity imaging. Blood chemistry allowed assessments of adipocytokines (TNF-α: tumor necrosis factor α, PAI active: active plasminogen activator inhibitor-1 and adiponectin) and glucose tolerance markers.

RESULTS

Regardless of exercise training modalities, lifestyle intervention improved significantly LV strains and strain rates (p<0.001) as well as metabolic and inflammatory profiles. Stepwise multiple regression analyses revealed EAT (β=0.73, p<0.01), log adiponectin (β=-0.13, p<0.05) and log TNF-α (β=0.15, p<0.05) as independent predictors of LV longitudinal strain (R(2)=0.74, p<0.001) while myocardial function improvement consecutive to lifestyle intervention was explained by EAT changes only (R(2)=0.54, p<0.001).

CONCLUSION

The mechanisms through which regional myocardial function is impaired in MetS and improved consecutive to intervention involved EAT, possibly via paracrine effects of adipocytokines. EAT should be considered as a future therapeutic target of interest in the treatment of metabolic-related cardiac diseases.

Monomeric adiponectin modulates nitric oxide release and calcium movements in porcine aortic endothelial cells in normal/high glucose conditions

AIMS

Perivascular adipose tissue can be involved in the process of cardiovascular pathology through the release of adipokines, namely adiponectins. Monomeric adiponectin has been shown to increase coronary blood flow in anesthetized pigs through increased nitric oxide (NO) release and the involvement of adiponectin receptor 1 (AdipoR1). The present study was therefore planned to examine the effects of monomeric adiponectin on NO release and Ca(2+) transients in porcine aortic endothelial cells (PAEs) in normal/high glucose conditions and the related mechanisms.

MAIN METHODS

PAEs were treated with monomeric adiponectin alone or in the presence of intracellular kinases blocker, AdipoR1 and Ca(2+)-ATPase pump inhibitors. The role of Na(+)/Ca(2+) exchanger was examined in experiments performed in zero Na(+) medium. NO release and intracellular Ca(2+) were measured through specific probes.

KEY FINDINGS

In PAE cultured in normal glucose conditions, monomeric adiponectin elevated NO production and [Ca(2+)]c. Similar effects were observed in high glucose conditions, although the response was lower and not transient. The Ca(2+) mobilized by monomeric adiponectin originated from an intracellular pool thapsigargin- and ATP-sensitive and from the extracellular space. Moreover, the effects of monomeric adiponectin were prevented by kinase blockers and AdipoR1 inhibitor. Finally, in normal glucose condition, a role for Na(+)/Ca(2+) exchanger and Ca(2+)-ATPase pump in restoring Ca(2+) was found.

SIGNIFICANCE

Our results add new information about the control of endothelial function elicited by monomeric adiponectin, which would be achieved by modulation of NO release and Ca(2+) transients. A signalling related to Akt, ERK1/2 and p38MAPK downstream AdipoR1 would be involved.

Intramyocardial Adipose-Derived Stem Cell Transplantation Increases Pericardial Fat with Recovery of Myocardial Function after Acute Myocardial Infarction

Intramyocardial injection of adipose-derived stem cells (ASC) with other cell types in acute myocardial infarction (AMI) animal models has consistently shown promising clinical regenerative capacities. We investigated the effects of intramyocardial injections of mouse ASC (mASC) with mouse endothelial cells (mEC) on left ventricular function and generation of pericardial fat in AMI rats. AMI rat models were created by ligating left anterior descending coronary artery and were randomly assigned into four groups: control (n = 10), mASC (n = 10), mEC (n = 10) and mASC+mEC (n = 10) via direct intramyocardial injections, and each rat received 1x10⁶ cells around three peri-infarct areas. Echocardiography and cardiac positron emission tomography (PET) were compared at baseline and on 28 days after AMI. Changes in left ventricular ejection fraction measured by PET, increased significantly in mASC and mASC+mEC groups compared to mEC and control groups. Furthermore, significant decreases in fibrosis were confirmed after sacrifice on 28 days in mASC and mASC+mEC groups. Successful cell engraftment was confirmed by positive Y-Chromosome staining in the transplantation region. Pericardial fat increased significantly in mASC and mASC+mEC groups compared to control group, and pericardial fat was shown to originate from the AMI rat. mASC group expressed higher adiponectin and lower leptin levels in plasma than control group. In addition, pericardial fat from AMI rats demonstrated increased phospho-AMPK levels and reduced phospho-ACC levels. Intramyocardial mASC transplantation after AMI in rats increased pericardial fat, which might play a protective role in the recovery of myocardial function after ischemic myocardial damage.

Intracoronary Des-Acyl Ghrelin Acutely Increases Cardiac Perfusion Through a Nitric Oxide-Related Mechanism in Female Anesthetized Pigs

Des-acyl ghrelin (DAG), the most abundant form of ghrelin in humans, has been found to reduce arterial blood pressure and prevent cardiac and endothelial cell apoptosis. Despite this, data regarding its direct effect on cardiac function and coronary blood flow, as well as the related involvement of autonomic nervous system and nitric oxide (NO), are scarce. We therefore examined these issues using both in vivo and in vitro studies. In 20 anesthetized pigs, intracoronary 100 pmol/mL DAG infusion with a constant heart rate and aortic blood pressure, increased coronary blood flow and NO release, whereas reducing coronary vascular resistances (P < .05). Dose responses to DAG were evaluated in five pigs. No effects on cardiac contractility/relaxation or myocardial oxygen consumption were observed. Moreover, whereas the blockade of muscarinic cholinoceptors (n = 5) or α- and β-adrenoceptors (n = 5 each) did not abolish the observed responses, NO synthase inhibition (n = 5) prevented the effects of DAG on coronary blood flow and NO release. In coronary artery endothelial cells, DAG dose dependently increased NO release through cAMP signaling and ERK1/2, Akt, and p38 MAPK involvement as well as the phosphorylation of endothelial NO synthase. In conclusion, in anesthetized pigs, DAG primarily increased cardiac perfusion through the involvement of NO release. Moreover, the phosphorylation of ERK1/2 and Akt appears to play roles in eliciting the observed NO production in coronary artery endothelial cells.

Longitudinal associations between adiponectin and cardiac structure differ by hypertensive status: Coronary Artery Risk Development in Young Adults

OBJECTIVE

We studied the longitudinal association between adiponectin and cardiac structure and function 10 years later stratified by hypertension status.

METHODS

Multicenter longitudinal study of black and white men and women that began in 1985-1986, when participants were 18-30 years old. Adiponectin was measured at year 15(2000-2001). Echocardiograms were completed at year 25(2010-2011). Participants were stratified by the presence of hypertension. Risk factor-adjusted echocardiographic variables were compared across adiponectin quintiles. Linear and quadratic regression models were also derived for risk factor-adjusted echocardiographic variables.

RESULTS

Relative to the lowest quintile of adiponectin, participants from the highest quintile had a 6% lower LV mass index (LVMi) among normotensives, and an 8% higher LVMi among hypertensives. Among normotensive participants, regression analysis demonstrated a linear inverse relationship between adiponectin and LV mass, LVMi, posterior wall thickness (PWT) and ventricular septal thickness (VST) (all p≤0.05). Among hypertensive participants, regression analysis demonstrated a U-shaped relationship between adiponectin and LV mass, LVMi, PWT and VST (p≤0.005 for all quadratic terms).

CONCLUSIONS

Among normotensive participants, higher adiponectin may be a useful marker of less adverse future cardiac structure. Further study is required to see if adiponectin receptor agonists may provide a benefit among these individuals. Among hypertensive participants, further study is required to assess the prognostic and therapeutic use of adiponectin.

[Adiponectin in health and disease]

Over the past 20 years after the discovery of adiponectin, much knowledge about its effect in health and disease has been gained. Adiponectin has antidiabetic, antiatherogenic, anti-inflammatory, immunomodulatory, metabolic, vasoprotective, and antiapoptotic properties. However, an understanding stems from the given literature review that much remains to be explored. Adiponectin has not yet commonly used in clinical practice, but cardiologists, endocrinologists, pediatricians, oncologists, and physicians of many specialties are interested in its preventive and therapeutic applications.

Adiponectin receptor-mediated signaling ameliorates cerebral cell damage and regulates the neurogenesis of neural stem cells at high glucose concentrations: an in vivo and in vitro study

In the central nervous system (CNS), hyperglycemia leads to neuronal damage and cognitive decline. Recent research has focused on revealing alterations in the brain in hyperglycemia and finding therapeutic solutions for alleviating the hyperglycemia-induced cognitive dysfunction. Adiponectin is a protein hormone with a major regulatory role in diabetes and obesity; however, its role in the CNS has not been studied yet. Although the presence of adiponectin receptors has been reported in the CNS, adiponectin receptor-mediated signaling in the CNS has not been investigated. In the present study, we investigated adiponectin receptor (AdipoR)-mediated signaling in vivo using a high-fat diet and in vitro using neural stem cells (NSCs). We showed that AdipoR1 protects cell damage and synaptic dysfunction in the mouse brain in hyperglycemia. At high glucose concentrations in vitro, AdipoR1 regulated the survival of NSCs through the p53/p21 pathway and the proliferation- and differentiation-related factors of NSCs via tailless (TLX). Hence, we suggest that further investigations are necessary to understand the cerebral AdipoR1-mediated signaling in hyperglycemic conditions, because the modulation of AdipoR1 might alleviate hyperglycemia-induced neuropathogenesis.