Can Adiponectin Help us to Target Diastolic Dysfunction?

From Bone Remodeling to Wound Healing: An miR-146a-5p-Loaded Nanocarrier Targets Endothelial Cells to Promote Angiogenesis

Wound healing is a complex challenge that demands urgent attention in the clinical realm. Efficient angiogenesis is a pivotal factor in promoting wound healing. microRNA-146a (miR-146a) inhibitor has angiogenic potential in the periodontal ligament. However, free microRNAs (miRNAs) are poorly delivered into cells due to their limited tissue specificity and low intracellular delivery efficiency. To address this hurdle, we developed a nanocarrier for targeted delivery of the miR-146a inhibitor into endothelial cells. It is composed of a polyethylenimine (PEI)-modified mesoporous silica nanoparticle (MSN) core and a pentapeptide (YIGSR) layer that recognizes endothelial cells. In vitro, we defined that the miR-146a inhibitor and adiponectin (ADP) can modulate angiogenesis and the remodeling of periodontal tissues by activating the ERK and Akt signaling pathways. Then, we confirm the specificity of YIGSR to endothelial cells, and importantly, the nanocarrier effectively delivers the miR-146a inhibitor into endothelial cells, promoting angiogenesis. In a C57 mouse skin wound model, the miR-146a inhibitor is successfully delivered into endothelial cells at the wound site using the nanocarrier, resulting in the formation of new blood vessels with strong CD31 expression. Additionally, no significant differences are found in the expression levels of inflammatory markers interleukin-6 and tumor necrosis factor-α. This outcome not only brings new strategies for angiogenesis but also exhibits broader implications for bone remodeling and wound healing. The breakthrough holds significance for future research and clinical interventions.

Adiponectin-mediated regulation of the adiponectin cascade in cardiovascular disease: Updates

The endocrine function of white adipose tissue is characterized by the synthesis of one its main hormones: adiponectin. Although the biological role of adiponectin has not been fully defined, clinical and experimental observations have shown that low plasma concentrations of adiponectin participate in the prevalence of insulin resistance and cardiovascular diseases, mainly in obese patients. Adiponectin also exerts its effects on the heart and blood vessels, thereby influencing their physiology. Studying the effects of adiponectin presents some complexities, primarily due to potential cross-interactions and interference with other pathways, such as the AdipoR1/R2 pathways. Under optimal conditions, the activation of the adiponectin cascade may involve signals such as AMPK and PPARα. Interestingly, these pathways may trigger similar responses, such as fatty acid oxidation. Understanding the downstream effectors of these pathways is crucial to comprehend the extent to which adiponectin signaling impacts metabolism. In this review, the aim is to explore the current mechanisms that regulate the adiponectin pathways. Additionally, updates on the major downstream factors involved in adiponectin signaling are provided, specifically in relation to metabolic syndrome and atherosclerosis.

HFpEF and Atrial Fibrillation: The Enigmatic Interplay of Dysmetabolism, Biomarkers, and Vascular Endothelial Dysfunction

Background. Heart failure with preserved ejection fraction (HFpEF) has a complex pathophysiology that encompasses systemic proinflammatory state and dysregulated levels of cardiometabolic and oxidative stress biomarkers. The prevalence of both HFpEF and atrial fibrillation (AF) is continuously rising, especially in the elderly. The aim of our study was to explore if there were any differences in biomarker levels and vascular function in the elderly patients with HFpEF with and without AF and to assess interconnections between clinically relevant biomarkers and cardiac and vascular function. Methods. This was a cross-sectional study of $\text{patients}\ge 65$ years with HFpEF who were divided into 2 groups based on the presence or absence of AF. We have sonographically assessed echocardiographic parameters of left ventricular systolic and diastolic function and the peripheral vascular function parameters, namely, pulse wave velocity (PWV) and flow-mediated dilation (FMD). NT-proBNP, irisin, leptin, adiponectin, insulin-like growth factor 1 (IGF-1), and malondialdehyde (MDA) blood levels were determined. Results. Fifty-two patients (mean age $80\pm 7$ years, 67% females) were included. Patients with HFpEF and AF had significantly lower levels of irisin (median 4.75 vs. 13.5 ng/mL, $p=0.007$ ), leptin (median 9.5 vs. 15.0 ng/L, $p=0.023$ ), and MDA (median 293 vs. 450 ng/mL, $p=0.017$ ) and significantly higher values of NT-proBNP (median 2365 vs. 529 ng/L, $p<0.001$ ) but not vascular function parameters, as compared to HFpEF patients without AF. MDA was significantly correlated with diastolic function ( $r=0.395$ , $p=0.007$ ) and FMD ( $r=0.394$ , $p=0.011$ ), while adiponectin was inversely associated with FMD ( $r=-0.325$ , $p=0.038$ ) and left ventricular ejection fraction ( $r=-0.319$ , $p=0.029$ ). Conclusions. Our results have demonstrated that patients with HFpEF and AF have significantly lower leptin, irisin, and MDA levels compared to patients with HFpEF but without AF. These results offer new insights into the complexity of vascular function and cardiometabolic and oxidative stress biomarkers in the context of HFpEF, AF, and aging.

Crossroads between Estrogen Loss, Obesity, and Heart Failure with Preserved Ejection Fraction

The prevalence of obesity and heart failure with preserved ejection fraction (HFpEF) increases significantly in postmenopausal women. Although obesity is a risk factor for left ventricular diastolic dysfunction (LVDD), the mechanisms that link the cessation of ovarian hormone production, and particularly estrogens, to the development of obesity, LVDD, and HFpEF in aging females are unclear. Clinical, and epidemiologic studies show that postmenopausal women with abdominal obesity (defined by waist circumference) are at greater risk for developing HFpEF than men or women without abdominal obesity. The study presents a review of clinical data that support a mechanistic link between estrogen loss plus obesity and left ventricular remodeling with LVDD. It also seeks to discuss potential cell and molecular mechanisms for estrogen-mediated protection against adverse adipocyte cell types, tissue depots, function, and metabolism that may contribute to LVDD and HFpEF.

Relationship between Adipokines and Cardiovascular Ultrasound Parameters in Metabolic-Dysfunction-Associated Fatty Liver Disease

(1) Background: The role of adipokines such as adiponectin and visfatin in metabolic-dysfunction-associated fatty liver disease (MAFLD) and cardiovascular disease remains unclear. Therefore, we aim to assess serum adiponectin and visfatin levels in MAFLD patients and associated cardiovascular parameters. (2) Methods: A cross-sectional study involving 80 participants (40 MAFLD patients, 40 controls), recruited between January and September 2020, was conducted, using both hepatic ultrasonography and SteatoTestTM to evaluate hepatic steatosis. Echocardiographic and Doppler parameters were assessed. Serum adipokines were measured using ELISA kits. (3) Results: Adiponectin and visfatin levels were not significantly different in MAFLD vs. controls. Visfatin was associated with mean carotid intima-media thickness (p-value = 0.047), while adiponectin was associated with left ventricular ejection fraction (LVEF) (p-value = 0.039) and E/A ratio (p-value = 0.002) in controls. The association between adiponectin and E/A ratio was significant in the univariate analysis at 95% CI (0.0049–0.1331, p-value = 0.035), but lost significance after the multivariate analysis. Although LVEF was not associated with adiponectin in the univariate analysis, significant values were observed after the multivariate analysis (95% CI (−1.83–−0.22, p-value = 0.015)). (4) Conclusions: No significant difference in serum adiponectin and visfatin levels in MAFLD patients vs. controls was found. Interestingly, although adiponectin levels were not associated with LVEF in the univariate analysis, a significant inversely proportional association was observed after the multivariate analysis.

The adiponectin signalling pathway - A therapeutic target for the cardiac complications of type 2 diabetes?

Diabetes is associated with an increased risk of heart failure (HF). This is commonly termed diabetic cardiomyopathy and is often characterised by increased cardiac fibrosis, pathological hypertrophy, increased oxidative and endoplasmic reticulum stress as well as diastolic dysfunction. Adiponectin is a cardioprotective adipokine that is downregulated in settings of type 2 diabetes (T2D) and obesity. Furthermore, both adiponectin receptors (AdipoR1 and R2) are also downregulated in these settings which further results in impaired cardiac adiponectin signalling and reduced cardioprotection. In many cardiac pathologies, adiponectin signalling has been shown to protect against cardiac remodelling and lipotoxicity, however its cardioprotective actions in T2D-induced cardiomyopathy remain unresolved. Diabetic cardiomyopathy has historically lacked effective treatment options. In this review, we summarise the current evidence for links between the suppressed adiponectin signalling pathway and cardiac dysfunction, in diabetes. We describe adiponectin receptor-mediated signalling pathways that are normally associated with cardioprotection, as well as current and potential future therapeutic approaches that could target this pathway as possible interventions for diabetic cardiomyopathy.

Molecular Mechanisms of Obesity-Linked Cardiac Dysfunction: An Up-Date on Current Knowledge

Obesity is defined as excessive body fat accumulation, and worldwide obesity has nearly tripled since 1975. Excess of free fatty acids (FFAs) and triglycerides in obese individuals promote ectopic lipid accumulation in the liver, skeletal muscle tissue, and heart, among others, inducing insulin resistance, hypertension, metabolic syndrome, type 2 diabetes (T2D), atherosclerosis, and cardiovascular disease (CVD). These diseases are promoted by visceral white adipocyte tissue (WAT) dysfunction through an increase in pro-inflammatory adipokines, oxidative stress, activation of the renin-angiotensin-aldosterone system (RAAS), and adverse changes in the gut microbiome. In the heart, obesity and T2D induce changes in substrate utilization, tissue metabolism, oxidative stress, and inflammation, leading to myocardial fibrosis and ultimately cardiac dysfunction. Peroxisome proliferator-activated receptors (PPARs) are involved in the regulation of carbohydrate and lipid metabolism, also improve insulin sensitivity, triglyceride levels, inflammation, and oxidative stress. The purpose of this review is to provide an update on the molecular mechanisms involved in obesity-linked CVD pathophysiology, considering pro-inflammatory cytokines, adipokines, and hormones, as well as the role of oxidative stress, inflammation, and PPARs. In addition, cell lines and animal models, biomarkers, gut microbiota dysbiosis, epigenetic modifications, and current therapeutic treatments in CVD associated with obesity are outlined in this paper.

Compression loading of osteoclasts attenuated microRNA-146a-5p expression, which promotes angiogenesis by targeting adiponectin

Osteoclastogenesis in alveolar bone induced by compression stress triggers orthodontic tooth movement. Compression stress also stimulates angiogenesis, which is essential for osteoclastogenesis. However, the effects of osteoclastogenesis induced by compression on angiogenesis are poorly understood. In vivo, we found the markers of angiogenesis increased during orthodontic bone remodeling. In vitro, osteoclast-derived exosomes increased proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs), as well as expression of vascular endothelial growth factor and CD31. The promotive effects of exosomes derived from compressed osteoclasts were greater than those derived from osteoclasts without compression. Next, we analyzed changes in the microRNA transcriptome after compression stress and focused on microRNA146a-5p (miR-146a), which was significantly decreased by compression. Transfection of an inhibitor of miR-146a stimulated angiogenesis of HUVECs while miR-146a mimics repressed angiogenesis. Adiponectin (ADP) was confirmed to be a target of miR-146a by dual luciferase reporter assay. In HUVECs treated with exosomes, we detected increased ADP which promoted angiogenesis. Knockdown of ADP in HUVECs reduced the promotive effects of exosomes. Our results demonstrate that the decreased miR-146a observed in osteoclasts after compression promotes angiogenesis by targeting ADP, suggesting a novel method to interfere with bone remodeling induced by compression stress.

MicroRNA profiles in plasma samples from young metabolically healthy obese patients and miRNA-21 are associated with diastolic dysfunction via TGF-β1/Smad pathway

Background

Metabolically healthy obese patients accounts for a large part of obese population, but its clinical significance and cardiac dysfunction are often underestimated. The microRNA profiles of metabolically healthy obese patients were investigated in the study, and the selected microRNA (miRNA) based on our microarray assay will be further verified in a relatively large metabolically healthy obese population.

Methods

microRNA microarray was performed from six metabolically healthy obese and 6 health control blood samples. Based on the bioinformatics analysis, we further measured RT‐PCR, fibrosis markers, echocardiograms, and TGF‐β1/Smad signaling pathway in 600 metabolically healthy obese population.

Results

We found that miRNAs expression characteristics in metabolically healthy obese groups were markedly different from healthy control group. MiRNA‐21 was significantly increased in the samples of metabolically healthy obese patients. Besides, miRNA‐21 levels were associated with cardiac fibrosis marker. Meanwhile, higher miRNA‐21 levels were related to elevated E/E′. Besides, patients with the highest miRNA‐21 quartile showed the lowest ratio of E/A. These associations between miRNA‐21 and diastolic function parameters were independent of obesity and other confounding variables. Of note, TGF‐β1and Smad 3 were significantly upregulated while Smad 7 was downregulated according to the miRNA‐21 quartiles in metabolically healthy obese group.

Conclusions

We demonstrated the profiles of circulating microRNAs in metabolically healthy obese patients. Increased plasma miRNA‐21 levels were related to impaired diastolic function independent of other relevant confounding variables. MiRNA‐21 could be one of the mechanistic links between obesity and diastolic dysfunction through regulating cardiac fibrosis via TGF‐β1/Smad signaling pathway in obese hearts, which may serve as a novel target of disease intervention.

Adiponectin Decreases Gastric Smooth Muscle Cell Excitability in Mice

Some adipokines known to regulate food intake at a central level can also affect gastrointestinal motor responses. These are recognized to be peripheral signals able to influence feeding behavior as well. In this view, it has been recently observed that adiponectin (ADPN), which seems to have a role in sending satiety signals at the central nervous system level, actually affects the mechanical responses in gastric strips from mice. However, at present, there are no data in the literature about the electrophysiological effects of ADPN on gastric smooth muscle. To this aim, we achieved experiments on smooth muscle cells (SMCs) of gastric fundus to find out a possible action on SMC excitability and on membrane phenomena leading to the mechanical response. Experiments were made inserting a microelectrode in a single cell of a muscle strip of the gastric fundus excised from adult female mice. We found that ADPN was able to hyperpolarize the resting membrane potential, to enhance the delayed rectifier K⁺ currents and to reduce the voltage-dependent Ca²⁺ currents. Our overall results suggest an inhibitory action of ADPN on gastric SMC excitation-contraction coupling. In conclusion, the depressant action of ADPN on the gastric SMC excitability, here reported for the first time, together with its well-known involvement in metabolism, might lead us to consider a possible contribution of ADPN also as a peripheral signal in the hunger-satiety cycle and thus in feeding behavior.

Adipocytes-released Peptides Involved in the Control of Gastrointestinal Motility

The present review focuses on adipocytes-released peptides known to be involved in the control of gastrointestinal motility, acting both centrally and peripherally. Thus, four peptides have been taken into account: leptin, adiponectin, nesfatin-1, and apelin. The discussion of the related physiological or pathophysiological roles, based on the most recent findings, is intended to underlie the close interactions among adipose tissue, central nervous system, and gastrointestinal tract. The better understanding of this complex network, as gastrointestinal motor responses represent peripheral signals involved in the regulation of food intake through the gut-brain axis, may also furnish a cue for the development of either novel therapeutic approaches in the treatment of obesity and eating disorders or potential diagnostic tools.

Heart Failure With Preserved Ejection Fraction and Adipose Tissue: A Story of Two Tales

Heart failure with preserved ejection fraction (HFpEF) is characterized by signs and symptoms of heart failure in the presence of a normal left ventricular ejection fraction. Although it accounts for up to 50% of all clinical presentations of heart failure, there are no evidence-based therapies for HFpEF to reduce morbidity and mortality. Additionally there is a lack of mechanistic understanding about the pathogenesis of HFpEF. HFpEF is associated with many comorbidities (such as obesity, hypertension, type 2 diabetes, atrial fibrillation, etc.) and is coupled with both cardiac and extra-cardiac abnormalities. Large outcome trials and registries reveal that being obese is a major risk factor for HFpEF. There is increasing focus on investigating the link between obesity and HFpEF, and the role that the adipose tissue and the heart, and the circulating milieu play in development and pathogenesis of HFpEF. This review discusses features of the obese-HFpEF phenotype and highlights proposed mechanisms implicated in the inter-tissue communication between adipose tissue and the heart in obesity-associated HFpEF.

The Significance of the Effect of Visceral Adiposity on Left Ventricular Diastolic Function in the General Population

We evaluated the association between visceral adiposity and left ventricular (LV) diastolic function in association with plasma adiponectin levels in 213 subjects without overt cardiac diseases. Abdominal visceral fat area was quantified by computed tomography. Excessive visceral fat was significantly associated with impaired diastolic parameters including E/A, E′ and E/E′. Although serum adiponectin levels decreased with increased visceral adiposity, there was no independent association between serum adiponectin levels and diastolic parameters, which suggest that the role of adiponectin in this association might be indirect.

Cardiovascular Adiponectin Resistance: The Critical Role of Adiponectin Receptor Modification

For the past two decades, a great deal of research has been published concerning adiponectin (APN), an abundant protein responsible for regulating numerous biologic functions including antioxidative, antinitrative, anti-inflammatory, and cardioprotective effects. A review of APN and its two major receptors is timely because of new findings concerning the mechanisms by which APN signaling may be altered in pathologic processes such as diabetes and heart failure. In this review we elaborate on currently known information regarding the physiologic role of APN and the known mechanisms underlying pathologic APN resistance - namely, APN receptor downregulation and phosphorylation - and provide insight regarding the future directions of APN research including an assessment of the clinical applicability of preventing pathologic post-translational modification of the APN receptor.

Targeting Obesity and Diabetes to Treat Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a major unmet medical need that is characterized by the presence of multiple cardiovascular and non-cardiovascular comorbidities. Foremost among these comorbidities are obesity and diabetes, which are not only risk factors for the development of HFpEF, but worsen symptoms and outcome. Coronary microvascular inflammation with endothelial dysfunction is a common denominator among HFpEF, obesity, and diabetes that likely explains at least in part the etiology of HFpEF and its synergistic relationship with obesity and diabetes. Thus, pharmacological strategies to supplement nitric oxide and subsequent cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) signaling may have therapeutic promise. Other potential approaches include exercise and lifestyle modifications, as well as targeting endothelial cell mineralocorticoid receptors, non-coding RNAs, sodium glucose transporter 2 inhibitors, and enhancers of natriuretic peptide protective NO-independent cGMP-initiated and alternative signaling, such as LCZ696 and phosphodiesterase-9 inhibitors. Additionally, understanding the role of adipokines in HFpEF may lead to new treatments. Identifying novel drug targets based on the shared underlying microvascular disease process may improve the quality of life and lifespan of those afflicted with both HFpEF and obesity or diabetes, or even prevent its occurrence.