Adiponectin protects against angiotensin II-induced cardiac fibrosis through activation of PPAR-alpha

Zingiberaceae in Cardiovascular Health: A review of adipokine modulation and endothelial protection via adipocyte-endothelial crosstalk mechanism

PURPOSE OF THE REVIEW

Although adipose tissue controls metabolism and protects vital organs, its importance to general health is being highlighted by the rise in type 2 diabetes and cardiovascular disease. Adipokines produced by adipose cells are essential regulators of metabolism, glucose homeostasis, and inflammatory response. It also protects vascular endothelial cells for its potential implications for cardiovascular protection. Understanding its intricate involvement in adipose tissue-endothelial communication is critical in developing targeted therapeutics to treat cardiovascular conditions linked with obesity and metabolic dysregulation. Spices from the Zingiberaceae family, such as cardamom, turmeric, and ginger, have anti-inflammatory and anti-oxidant properties that help reduce oxidative stress, vascular dysfunction, and adipocyte-endothelial crosstalk which are all linked to the etiology of CVD. Comprehensive molecular insights into how they modulate adipokine signalling, inflammatory pathways, and ROS-induced adipocyte-vascular interactions remain unexplored, demanding additional translational and clinical validation. With an emphasis on patients with obesity and metabolic dysregulation, the investigation aims to elucidate the mechanisms by which the spice as whole/bioactive constituents of the Zingiberaceae family may provide protection against CVD by integrating previous studies.

RECENT FINDINGS

Current research continues to support the use of spices from the Zingiberaceae family, such as ginger, turmeric, cardamom, and pepper, as potential therapeutic agents for addressing metabolic complications like obesity, type II diabetes, and CVDs. These natural remedies may modulate adipocyte-endothelial crosstalk and inflammation by modulating important signalling pathways such as AMPK, AKT, PPAR, and NF-κB..

CONCLUSION

This review provides a complete summary of existing knowledge, opening the way for future research and prospective therapeutic applications of Zingiberaceae spices in cardiovascular health management.

The Involvement of Mitochondrial Dysfunction during the Development of Adenomyosis

The etiology of adenomyosis remains unclear. The association between epithelial-mesenchymal transition (EMT) and mitochondrial dysfunction is involved in fibrotic diseases. Adenomyosis is defined as the existence of endometrial glands and stroma in the myometrium with EMT and ultimate fibrosis. This study was designed to investigate the involvement of mitochondrial dysfunction in fibrotic adenomyosis. Mitochondrial integrity was examined in mouse and human adenomyotic tissues. Control and tamoxifen-treated mice were treated with 3-nitropropionic acid (a mitochondrial dysfunction inducer) and NG-nitro-L-arginine methyl ester (a mitochondrial dysfunction inhibitor), respectively, at postnatal day 21, followed by an evaluation of adenomyosis, EMT, and fibrosis as well as the expression of mitophagy, oxidative stress, and transforming growth factor-β1 (TGF-β1). The gene profiles of adenomyotic uteri were examined at postnatal day 42. Adenomyotic mice exhibited increased development of EMT and fibrosis. Adenomyotic tissues showed consistent mitochondrial destruction with increased fission, mitophagosomes, and lysosomes. Besides, mitophagy, oxidative stress, and TGF-β1 levels were consistently increased. The mitochondrial dysfunction, the development of mitophagy and fibrosis, and TGF-β1 expression were induced by 3-nitropropionic acid in control uteri. In contrast, NG-nitro-L-arginine methyl ester attenuated mitochondrial dysfunction, mitophagy, fibrosis, and TGF-β1 in adenomyotic uteri. Gene profiling demonstrated increased expression of mitochondrial dysfunction-related genes in adenomyotic uteri. This indicates that mitochondrial dysfunction-induced TGF-β1 dysregulation and fibrosis are associated with the development of adenomyosis.

Adipokines and Cardiometabolic Heart Failure with Preserved Ejection Fraction: A State-of-the-Art Review

BACKGROUND

Cardiometabolic heart failure with preserved ejection fraction (HFpEF) is largely driven by obesity-related factors, including adipokines and bioactive peptides primarily secreted by the adipose tissue, such as leptin, adiponectin, and resistin. These molecules link metabolic dysregulation to cardiovascular dysfunction, influencing HFpEF progression and patient outcomes Methods: A comprehensive literature search was conducted in PubMed up to 20 November 2024, using keywords and MeSH terms, such as "HFpEF", "adipokines", "leptin", "adiponectin", and "resistin", yielding 723 results. Boolean operators refined the search, and reference lists of key studies were reviewed. After screening for duplicates and irrelevant studies, 103 articles were included, providing data on adipokines' roles in HFpEF pathophysiology, biomarkers, and therapeutic implications.

RESULTS

Both preclinical and clinical studies have demonstrated that adipokines play a role in modulating cardiovascular function, thereby contributing to the development of cardiometabolic HFpEF. Leptin promotes myocardial hypertrophy, fibrosis, endothelial dysfunction, and inflammation, though contradictory evidence suggests potential cardioprotective roles in subgroups like obese African American women. Adiponectin generally offers protective effects but presents a paradox, where elevated levels may correlate with worse outcomes, which may reflect either a compensatory response to cardiac dysfunction or a maladaptive state characterized by adiponectin resistance. Resistin is associated with increased cardiovascular risk through pro-inflammatory and pro-fibrotic effects, though its role in HFpEF requires further clarification. Other adipokines, like retinol-binding protein 4 and omentin-1, have emerged as potential contributors. Despite growing insights, clinical translation remains limited, underscoring a significant gap between experimental evidence and therapeutic application.

CONCLUSIONS

Future research should focus on targeted interventions that modulate adipokine pathways to potentially improve HFpEF outcomes. Innovative treatment strategies addressing underlying metabolic disturbances and adipokine dysregulation are essential for advancing the management of this challenging condition.

AMPK and O-GlcNAcylation: interplay in cardiac pathologies and heart failure

Heart failure (HF) represents a multifaceted clinical syndrome characterized by the heart's inability to pump blood efficiently to meet the body's metabolic demands. Despite advances in medical management, HF remains a major cause of morbidity and mortality worldwide. In recent years, considerable attention has been directed toward understanding the molecular mechanisms underlying HF pathogenesis, with a particular focus on the role of AMP-activated protein kinase (AMPK) and protein O-GlcNAcylation. This review comprehensively examines the current understanding of AMPK and O-GlcNAcylation signalling pathways in HF, emphasizing their interplay and dysregulation. We delve into the intricate molecular mechanisms by which AMPK and O-GlcNAcylation contribute to cardiac energetics, metabolism, and remodelling, highlighting recent preclinical and clinical studies that have explored novel therapeutic interventions targeting these pathways.

Chronic intermittent hypoxia triggers cardiac fibrosis: Role of epididymal white adipose tissue senescent remodeling?

AIM

Obstructive sleep apnea (OSA) is a growing health problem affecting nearly 1 billion people worldwide. The landmark feature of OSA is chronic intermittent hypoxia (CIH), accounting for multiple organ damage, including heart disease. CIH profoundly alters both visceral white adipose tissue (WAT) and heart structure and function, but little is known regarding inter-organ interaction in the context of CIH. We recently showed that visceral WAT senescence drives myocardial alterations in aged mice without CIH. Here, we aimed at investigating whether CIH induces a premature visceral WAT senescent phenotype, triggering subsequent cardiac remodeling.

METHODS

In a first experiment, 10-week-old C57bl6J male mice (n = 10/group) were exposed to 14 days of CIH (8 h daily, 5%-21% cyclic inspired oxygen fraction, 60 s per cycle). In a second series, mice were submitted to either epididymal WAT surgical lipectomy or sham surgery before CIH exposure. Finally, we used p53 deficient mice or Wild-type (WT) littermates, also exposed to the same CIH protocol. Epididymal WAT was assessed for fibrosis, DNA damages, oxidative stress, markers of senescence (p16, p21, and p53), and inflammation by RT-qPCR and histology, and myocardium was assessed for fibrosis and cardiomyocyte hypertrophy.

RESULTS

CIH-induced epididymal WAT remodeling characterized by increased fibrosis, oxidative stress, DNA damage response, inflammation, and increased expression of senescent markers. CIH-induced epididymal WAT remodeling was associated with subtle and early myocardial interstitial fibrosis. Both epididymal WAT surgical lipectomy and p53 deletion prevented CIH-induced myocardial fibrosis.

CONCLUSION

Short-term exposure to CIH induces epididymal WAT senescent remodeling and cardiac interstitial fibrosis, the latter being prevented by lipectomy. This finding strongly suggests visceral WAT senescence as a new target to mitigate OSA-related cardiac disorders.

Exogenous APN protects normal tissues from radiation-induced oxidative damage and fibrosis in mice and prostate cancer patients with higher levels of APN have less radiation-induced toxicities

Radiation causes damage to normal tissues that leads to increased oxidative stress, inflammation, and fibrosis, highlighting the need for the selective radioprotection of healthy tissues without hindering radiotherapy effectiveness in cancer. This study shows that adiponectin, an adipokine secreted by adipocytes, protects normal tissues from radiation damage invitro and invivo. Specifically, adiponectin (APN) reduces chronic oxidative stress and fibrosis in irradiated mice. Importantly, APN also conferred no protection from radiation to prostate cancer cells. Adipose tissue is the primary source of circulating endogenous adiponectin. However, this study shows that adipose tissue is sensitive to radiation exposure exhibiting morphological changes and persistent oxidative damage. In addition, radiation results in a significant and chronic reduction in blood APN levels from adipose tissue in mice and human prostate cancer patients exposed to pelvic irradiation. APN levels negatively correlated with bowel toxicity and overall toxicities associated with radiotherapy in prostate cancer patients. Thus, protecting, or modulating APN signaling may improve outcomes for prostate cancer patients undergoing radiotherapy.

The mysterious association between adiponectin and endometriosis

Adiponectin is a pleiotropic cytokine predominantly derived from adipose tissue. In addition to its role in regulating energy metabolism, adiponectin may also be related to estrogen-dependent diseases, and many studies have confirmed its involvement in mediating diverse biological processes, including apoptosis, autophagy, inflammation, angiogenesis, and fibrosis, all of which are related to the pathogenesis of endometriosis. Although many researchers have reported low levels of adiponectin in patients with endometriosis and suggested that it may serve as a protective factor against the development of the disease. Therefore, the purpose of this review was to provide an up-to-date summary of the roles of adiponectin and its downstream cytokines and signaling pathways in the aforementioned biological processes. Further systematic studies on the molecular and cellular mechanisms of action of adiponectin may provide novel insights into the pathophysiology of endometriosis as well as potential therapeutic targets.

Systematic transcriptome-wide meta-analysis across endocrine disrupting chemicals reveals shared and unique liver pathways, gene networks, and disease associations

Cardiometabolic disorders (CMD) are a growing public health problem across the world. Among the known cardiometabolic risk factors are compounds that induce endocrine and metabolic dysfunctions, such as endocrine disrupting chemicals (EDCs). To date, how EDCs influence molecular programs and cardiometabolic risks has yet to be fully elucidated, especially considering the complexity contributed by species-, chemical-, and dose-specific effects. Moreover, different experimental and analytical methodologies employed by different studies pose challenges when comparing findings across studies. To explore the molecular mechanisms of EDCs in a systematic manner, we established a data-driven computational approach to meta-analyze 30 human, mouse, and rat liver transcriptomic datasets for 4 EDCs, namely bisphenol A (BPA), bis(2-ethylhexyl) phthalate (DEHP), tributyltin (TBT), and perfluorooctanoic acid (PFOA). Our computational pipeline uniformly re-analyzed pre-processed quality-controlled microarray data and raw RNAseq data, derived differentially expressed genes (DEGs) and biological pathways, modeled gene regulatory networks and regulators, and determined CMD associations based on gene overlap analysis. Our approach revealed that DEHP and PFOA shared stable transcriptomic signatures that are enriched for genes associated with CMDs, suggesting similar mechanisms of action such as perturbations of peroxisome proliferator-activated receptor gamma (PPARγ) signaling and liver gene network regulators VNN1 and ACOT2. In contrast, TBT exhibited highly divergent gene signatures, pathways, network regulators, and disease associations from the other EDCs. In addition, we found that the rat, mouse, and human BPA studies showed highly variable transcriptomic patterns, providing molecular support for the variability in BPA responses. Our work offers insights into the commonality and differences in the molecular mechanisms of various EDCs and establishes a streamlined data-driven workflow to compare molecular mechanisms of environmental substances to elucidate the underlying connections between chemical exposure and disease risks.

A Prediction Model for Sight-Threatening Diabetic Retinopathy Based on Plasma Adipokines among Patients with Mild Diabetic Retinopathy

Background

Accumulating evidence has suggested a link between adipokines and diabetic retinopathy (DR). This study is aimed at investigating the risk factors for sight-threatening DR (STDR) and establishing a prognostic model for predicting STDR among a high-risk population of patients with type 2 diabetes mellitus (T2DM).

Methods

Plasma concentrations of adipokines were determined by enzyme-linked immunosorbent assay. In the case-control set, principal component analysis (PCA) was performed to select optimal predictive cytokines for STDR, involving severe nonproliferative DR (NPDR) and proliferative DR. Support vector machine (SVM) was used to examine the possible combination of baseline plasma adipokines to discriminate the patients with mild NPDR who will later develop STDR. An individual prospective cohort with a follow-up period of 3 years was used for the external validation.

Results

In both training and testing sets, involving 306 patients with T2DM, median levels of plasma adiponectin (APN), leptin, and fatty acid-binding protein 4 (FABP4) were significantly higher in the STDR group than those in mild NPDR. Except for adipsin, the other three adipokines, FABP4, APN, and leptin, were selected by PCA and integrated into SVM. The accuracy of the multivariate SVM classification model was acceptable in both the training set (AUC = 0.81, sensitivity = 71%, and specificity = 91%) and the testing set (AUC = 0.77, sensitivity = 61%, and specificity = 92%). 110 T2DM patients with mild NPDR, the high-risk population of STDR, were enrolled for external validation. Based on the SVM, the risk of each patient was calculated. More STDR occurred in the high-risk group than in the low-risk group, which were grouped by the median value of APN, FABP4, and leptin, respectively. The model was validated in an individual cohort using SVM with the AUC, sensitivity, and specificity reaching 0.77, 64%, and 91%, respectively.

Conclusions

Adiponectin, leptin, and FABP4 were demonstrated to be associated with the severity of DR and maybe good predictors for STDR, suggesting that adipokines may play an important role in the pathophysiology of DR development.

Obesity phenotypes and cardiovascular risk: From pathophysiology to clinical management

Obesity epidemic reached the dimensions of a real global health crisis with more than one billion people worldwide living with obesity. Multiple obesity-related mechanisms cause structural, functional, humoral, and hemodynamic alterations with cardiovascular (CV) deleterious effects. A correct assessment of the cardiovascular risk in people with obesity is critical for reducing mortality and preserving quality of life. The correct identification of the obesity status remains difficult as recent evidence suggest that different phenotypes of obesity exist, each one associated with different degrees of CV risk. Diagnosis of obesity cannot depend only on anthropometric parameters but should include a precise assessment of the metabolic status. Recently, the World Heart Federation and World Obesity Federation provided an action plan for management of obesity-related CV risk and mortality, stressing for the instauration of comprehensive structured programs encompassing multidisciplinary teams. In this review we aim at providing an updated summary regarding the different obesity phenotypes, their specific effects on CV risk and differences in clinical management.

Adipolin protects against renal injury via PPARα-dependent reduction of inflammasome activation

Although chronic kidney disease (CKD) is a major health problem worldwide, its underlining mechanism is incompletely understood. We previously identified adipolin as an adipokine which provides benefits for cardiometabolic diseases. Here, we investigated the role of adipolin in the development of CKD. Adipolin-deficiency exacerbated urinary albumin excretion, tubulointerstitial fibrosis and oxidative stress of remnant kidneys in mice after subtotal nephrectomy through inflammasome activation. Adipolin positively regulated the production of ketone body, β-hydroxybutyrate (BHB) and expression of a catalytic enzyme producing BHB, HMGCS2 in the remnant kidney. Treatment of proximal tubular cells with adipolin attenuated inflammasome activation through the PPARα/HMGCS2-dependent pathway. Furthermore, systemic administration of adipolin to wild-type mice with subtotal nephrectomy ameliorated renal injury, and these protective effects of adipolin were diminished in PPARα-deficient mice. Thus, adipolin protects against renal injury by reducing renal inflammasome activation through its ability to induce HMGCS2-dependent ketone body production via PPARα activation.

Biomarkers of Atrial Fibrillation Recurrence in Patients with Paroxysmal or Persistent Atrial Fibrillation Following External Direct Current Electrical Cardioversion

Atrial fibrillation (AF) is associated with atrial remodeling, cardiac dysfunction, and poor clinical outcomes. External direct current electrical cardioversion is a well-developed urgent treatment strategy for patients presenting with recent-onset AF. However, there is a lack of accurate predictive serum biomarkers to identify the risks of AF relapse after electrical cardioversion. We reviewed the currently available data and interpreted the findings of several studies revealing biomarkers for crucial elements in the pathogenesis of AF and affecting cardiac remodeling, fibrosis, inflammation, endothelial dysfunction, oxidative stress, adipose tissue dysfunction, myopathy, and mitochondrial dysfunction. Although there is ample strong evidence that elevated levels of numerous biomarkers (such as natriuretic peptides, C-reactive protein, galectin-3, soluble suppressor tumorigenicity-2, fibroblast growth factor-23, turn-over collagen biomarkers, growth differential factor-15) are associated with AF occurrence, the data obtained in clinical studies seem to be controversial in terms of their predictive ability for post-cardioversion outcomes. Novel circulating biomarkers are needed to elucidate the modality of this approach compared with conventional predictive tools. Conclusions: Biomarker-based strategies for predicting events after AF treatment require extensive investigation in the future, especially in the presence of different gender and variable comorbidity profiles. Perhaps, a multiple biomarker approach exerts more utilization for patients with different forms of AF than single biomarker use.

The Role of Cardiac Fibrosis in Diabetic Cardiomyopathy: From Pathophysiology to Clinical Diagnostic Tools

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by hyperglycemia due to inadequate insulin secretion, resistance, or both. The cardiovascular complications of DM are the leading cause of morbidity and mortality in diabetic patients. There are three major types of pathophysiologic cardiac remodeling including coronary artery atherosclerosis, cardiac autonomic neuropathy, and DM cardiomyopathy in patients with DM. DM cardiomyopathy is a distinct cardiomyopathy characterized by myocardial dysfunction in the absence of coronary artery disease, hypertension, and valvular heart disease. Cardiac fibrosis, defined as the excessive deposition of extracellular matrix (ECM) proteins, is a hallmark of DM cardiomyopathy. The pathophysiology of cardiac fibrosis in DM cardiomyopathy is complex and involves multiple cellular and molecular mechanisms. Cardiac fibrosis contributes to the development of heart failure with preserved ejection fraction (HFpEF), which increases mortality and the incidence of hospitalizations. As medical technology advances, the severity of cardiac fibrosis in DM cardiomyopathy can be evaluated by non-invasive imaging modalities such as echocardiography, heart computed tomography (CT), cardiac magnetic resonance imaging (MRI), and nuclear imaging. In this review article, we will discuss the pathophysiology of cardiac fibrosis in DM cardiomyopathy, non-invasive imaging modalities to evaluate the severity of cardiac fibrosis, and therapeutic strategies for DM cardiomyopathy.

The role of adiponectin in cardiovascular disease

Cardiovascular disease (CVD) is a common disease that seriously threatens the health of human beings, especially middle-aged and elderly people over 50 years old. It has the characteristics of high prevalence, high disability rate and high mortality rate. Previous studies have shown that adiponectin has therapeutic effects on a variety of CVDs. As a key adipokine, adiponectin, is an abundant peptide-regulated hormone that is mainly released by adipocytes and cardiomyocytes, as well as endothelial and skeletal cells. Adiponectin can protect against CVD by improving lipid metabolism, protecting vascular endothelial cells and inhibiting foam cell formation and vascular smooth muscle cell proliferation. Further investigation of the molecular and cellular mechanisms underlying the adiponectin system may provide new ideas for the treatment of CVD. Herein, this review aims to describe the structure and function of adiponectin and adiponectin receptors, introduce the function of adiponectin in the protection of cardiovascular disease and analyze the potential use and clinical significance of this hormone in the protection and treatment of cardiovascular disease, which shows that adiponectin can be expected to become a new therapeutic target and biomarker for the diagnosis and treatment of CVD.

A novel caffeic acid derivative prevents angiotensin II-induced cardiac remodeling

Differentiation of cardiac fibroblasts into myofibroblasts is a critical event in the progression of cardiac fibrosis that causes pathological cardiac remodeling. Cardiac fibrosis is a hallmark of heart disease and is associated with a stiff myocardium and heart failure. This study investigated the effect of caffeic acid ethanolamide (CAEA), a novel caffeic acid derivative, on cardiac remodeling. Angiotensin (Ang) II was used to induce cardiac remodeling both in cell and animal studies. Treating cardiac fibroblast with CAEA in Ang II-exposed cell cultures reduced the expression of fibrotic marker α-smooth muscle actin (α-SMA) and collagen and the production of superoxide, indicating that CAEA inhibited the differentiation of fibroblast into myofibroblast after Ang II exposure. CAEA protects against Ang II-induced cardiac fibrosis and dysfunction in vivo, characterized by the alleviation of collagen accumulation and the recovery of ejection fraction. In addition, CAEA decreased Ang II-induced transforming growth factor-β (TGF-β) expression and reduced NOX4 expression and oxidative stress in a SMAD-dependent pathway. CAEA participated in the regulation of Ang II-induced TGF-β/SMAD/NOX4 signaling to prevent the differentiation of fibroblast into myofibroblast and thus exerted a cardioprotective effect. Our data support the administration of CAEA as a viable method for preventing the progression of Ang II-induced cardiac remodeling.

Gut bacteria-derived 3-phenylpropionylglycine mitigates adipocyte differentiation of 3T3-L1 cells by inhibiting adiponectin-PPAR pathway

BACKGROUND

Gut microbiota provide numerous types of metabolites that humans cannot produce and have a huge influence on the host metabolism. Accordingly, gut bacteria-derived metabolites can be employed as a resource to develop anti-obesity and metabolism-modulating drugs.

OBJECTIVE

This study aimed to examine the anti-adipogenic effect of 3-phenylpropionylglycine (PPG), which is a glycine conjugate of bacteria-derived 3-phenylpropionic acid (PPA).

METHODS

The effect of PPG on preadipocyte-to-adipocyte differentiation was evaluated in 3T3-L1 differentiation models and the degree of the differentiation was estimated by Oil red O staining. The molecular mechanisms of the PPG effect were investigated with transcriptome analyses using RNA-sequencing and quantitative real-time PCR.

RESULTS

PPG suppressed lipid droplet accumulation during the adipogenic differentiation of 3T3-L1 cells, which is attributed to down-regulation of lipogenic genes such as acetyl CoA carboxylase 1 (Acc1) and fatty acid synthase (Fasn). However, other chemicals with chemical structures similar to PPG, including cinnamoylglycine and hippuric acid, had little effect on the lipid accumulation of 3T3-L1 cells. In transcriptomic analysis, PPG suppressed the expression of adipogenesis and metabolism-related gene sets, which is highly associated with downregulation of the peroxisome proliferator-activated receptor (PPAR) signaling pathway. Protein-protein association network analysis suggested adiponectin as a hub gene in the network of genes that were differentially expressed genes in response to PPG treatment.

CONCLUSION

PPG inhibits preadipocyte-to-adipocyte differentiation by suppressing the adiponectin-PPAR pathway. These data provide a potential candidate from bacteria-derived metabolites with anti-adipogenic effects.

Role of Adiponectin in Cardiovascular Diseases Related to Glucose and Lipid Metabolism Disorders

Lifestyle changes have led to increased incidence of cardiovascular disease (CVD); therefore, potential targets against CVD should be explored to mitigate its risks. Adiponectin (APN), an adipokine secreted by adipose tissue, has numerous beneficial effects against CVD related to glucose and lipid metabolism disorders, including regulation of glucose and lipid metabolism, increasing insulin sensitivity, reduction of oxidative stress and inflammation, protection of myocardial cells, and improvement in endothelial cell function. These effects demonstrate the anti-atherosclerotic and antihypertensive properties of APN, which could aid in improving myocardial hypertrophy, and reducing myocardial ischemia/reperfusion (MI/R) injury and myocardial infarction. APN can also be used for diagnosing and predicting heart failure. This review summarizes and discusses the role of APN in the treatment of CVD related to glucose and lipid metabolism disorders, and explores future APN research directions and clinical application prospects. Future studies should elucidate the signaling pathway network of APN cardiovascular protective effects, which will facilitate clinical trials targeting APN for CVD treatment in a clinical setting.

The importance of caveolin as a target in the prevention and treatment of diabetic cardiomyopathy

The diabetic population has been increasing in the past decades and diabetic cardiomyopathy (DCM), a pathology that is defined by the presence of cardiac remodeling and dysfunction without conventional cardiac risk factors such as hypertension and coronary heart diseases, would eventually lead to fatal heart failure in the absence of effective treatment. Impaired insulin signaling, commonly known as insulin resistance, plays an important role in the development of DCM. A family of integral membrane proteins named caveolins (mainly caveolin-1 and caveolin-3 in the myocardium) and a protein hormone adiponectin (APN) have all been shown to be important for maintaining normal insulin signaling. Abnormalities in caveolins and APN have respectively been demonstrated to cause DCM. This review aims to summarize recent research findings of the roles and mechanisms of caveolins and APN in the development of DCM, and also explore the possible interplay between caveolins and APN.

IMM-H007 attenuates isoprenaline-induced cardiac fibrosis through targeting TGFβ1 signaling pathway

Upon chronic stress, β-adrenergic receptor activation induces cardiac fibrosis and leads to heart failure. The small molecule compound IMM-H007 has demonstrated protective effects in cardiovascular diseases via activation of AMP-activated protein kinase (AMPK). This study aimed to investigate IMM-H007 effects on cardiac fibrosis induced by β-adrenergic receptor activation. Because adenosine analogs also exert AMPK-independent effects, we assessed AMPK-dependent and -independent IMM-H007 effects in murine models of cardiac fibrosis. Continual subcutaneous injection of isoprenaline for 7 days caused cardiac fibrosis and cardiac dysfunction in mice in vivo. IMM-H007 attenuated isoprenaline-induced cardiac fibrosis, diastolic dysfunction, α-smooth muscle actin expression, and collagen I deposition in both wild-type and AMPKα2-/- mice. Moreover, IMM-H007 inhibited transforming growth factor β1 (TGFβ1) expression in wild-type, but not AMPKα2-/- mice. By contrast, IMM-H007 inhibited Smad2/3 signaling downstream of TGFβ1 in both wild-type and AMPKα2-/- mice. Surface plasmon resonance and molecular docking experiments showed that IMM-H007 directly interacts with TGFβ1, inhibits its binding to TGFβ type II receptors, and downregulates the Smad2/3 signaling pathway downstream of TGFβ1. These findings suggest that IMM-H007 inhibits isoprenaline-induced cardiac fibrosis via both AMPKα2-dependent and -independent mechanisms. IMM-H007 may be useful as a novel TGFβ1 antagonist.

Crosstalk Between Adipose Tissue and the Heart: An Update

It is important to understand how different human organs coordinate and interact with each other. Since obesity and cardiac disease frequently coincide, the crosstalk between adipose tissues and heart has drawn attention. We appreciate that specific peptides/proteins, lipids, nucleic acids, and even organelles shuttle between the adipose tissues and heart. These bioactive components can profoundly affect the metabolism of cells in distal organs, including heart. Importantly, this process can be dysregulated under pathophysiological conditions. This also opens the door to efforts targeting these mediators as potential therapeutic strategies to treat patients who manifest diabetes and cardiovascular disease. Here, we summarize the recent progress toward a better understanding of how the adipose tissues and heart interact with each other.

Association of Obesity With COVID-19 Severity and Mortality: An Updated Systemic Review, Meta-Analysis, and Meta-Regression

Background

Obesity affects the course of critical illnesses. We aimed to estimate the association of obesity with the severity and mortality in coronavirus disease 2019 (COVID-19) patients.

Data Sources

A systematic search was conducted from the inception of the COVID-19 pandemic through to 13 October 2021, on databases including Medline (PubMed), Embase, Science Web, and Cochrane Central Controlled Trials Registry. Preprint servers such as BioRxiv, MedRxiv, ChemRxiv, and SSRN were also scanned.

Study Selection and Data Extraction

Full-length articles focusing on the association of obesity and outcome in COVID-19 patients were included. Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were used for study selection and data extraction. Our Population of interest were COVID-19 positive patients, obesity is our Intervention/Exposure point, Comparators are Non-obese vs obese patients The chief outcome of the study was the severity of the confirmed COVID-19 positive hospitalized patients in terms of admission to the intensive care unit (ICU) or the requirement of invasive mechanical ventilation/intubation with obesity. All-cause mortality in COVID-19 positive hospitalized patients with obesity was the secondary outcome of the study.

Results

In total, 3,140,413 patients from 167 studies were included in the study. Obesity was associated with an increased risk of severe disease (RR=1.52, 95% CI 1.41-1.63, p<0.001, I2 = 97%). Similarly, high mortality was observed in obese patients (RR=1.09, 95% CI 1.02-1.16, p=0.006, I2 = 97%). In multivariate meta-regression on severity, the covariate of the female gender, pulmonary disease, diabetes, older age, cardiovascular diseases, and hypertension was found to be significant and explained R2 = 40% of the between-study heterogeneity for severity. The aforementioned covariates were found to be significant for mortality as well, and these covariates collectively explained R2 = 50% of the between-study variability for mortality.

Conclusions

Our findings suggest that obesity is significantly associated with increased severity and higher mortality among COVID-19 patients. Therefore, the inclusion of obesity or its surrogate body mass index in prognostic scores and improvement of guidelines for patient care management is recommended.

Cardiomyocyte peroxisome proliferator-activated receptor α is essential for energy metabolism and extracellular matrix homeostasis during pressure overload-induced cardiac remodeling

Peroxisome proliferator-activated receptor α (PPARα), a ligand-activated nuclear receptor critical for systemic lipid homeostasis, has been shown closely related to cardiac remodeling. However, the roles of cardiomyocyte PPARα in pressure overload-induced cardiac remodeling remains unclear because of lacking a cardiomyocyte-specific Ppara-deficient (Ppara^ΔCM) mouse model. This study aimed to determine the specific role of cardiomyocyte PPARα in transverse aortic constriction (TAC)-induced cardiac remodeling using an inducible Ppara^ΔCM mouse model. Ppara^ΔCM and Ppara^fl/fl mice were randomly subjected to sham or TAC for 2 weeks. Cardiomyocyte PPARα deficiency accelerated TAC-induced cardiac hypertrophy and fibrosis. Transcriptome analysis showed that genes related to fatty acid metabolism were dramatically downregulated, but genes critical for glycolysis were markedly upregulated in Ppara^ΔCM hearts. Moreover, the hypertrophy-related genes, including genes involved in extracellular matrix (ECM) remodeling, cell adhesion, and cell migration, were upregulated in hypertrophic Ppara^ΔCM hearts. Western blot analyses demonstrated an increased HIF1α protein level in hypertrophic Ppara^ΔCM hearts. PET/CT analyses showed an enhanced glucose uptake in hypertrophic Ppara^ΔCM hearts. Bioenergetic analyses further revealed that both basal and maximal oxygen consumption rates and ATP production were significantly increased in hypertrophic Ppara^fl/fl hearts; however, these increases were markedly blunted in Ppara^ΔCM hearts. In contrast, hypertrophic Ppara^ΔCM hearts exhibited enhanced extracellular acidification rate (ECAR) capacity, as reflected by increased basal ECAR and glycolysis but decreased glycolytic reserve. These results suggest that cardiomyocyte PPARα is crucial for the homeostasis of both energy metabolism and ECM during TAC-induced cardiac remodeling, thus providing new insights into potential therapeutics of cardiac remodeling-related diseases.

Remodeling and Fibrosis of the Cardiac Muscle in the Course of Obesity-Pathogenesis and Involvement of the Extracellular Matrix

Obesity is a growing epidemiological problem, as two-thirds of the adult population are carrying excess weight. It is a risk factor for the development of cardiovascular diseases (hypertension, ischemic heart disease, myocardial infarct, and atrial fibrillation). It has also been shown that chronic obesity in people may be a cause for the development of heart failure with preserved ejection fraction (HFpEF), whose components include cellular hypertrophy, left ventricular diastolic dysfunction, and increased extracellular collagen deposition. Several animal models with induced obesity, via the administration of a high-fat diet, also developed increased heart fibrosis as a result of extracellular collagen accumulation. Excessive collagen deposition in the extracellular matrix (ECM) in the course of obesity may increase the stiffness of the myocardium and thereby deteriorate the heart diastolic function and facilitate the occurrence of HFpEF. In this review, we include a rationale for that process, including a discussion about possible putative factors (such as increased renin–angiotensin–aldosterone activity, sympathetic overdrive, hemodynamic alterations, hypoadiponectinemia, hyperleptinemia, and concomitant heart diseases). To address the topic clearly, we include a description of the fundamentals of ECM turnover, as well as a summary of studies assessing collagen deposition in obese individuals.

Adiponectin accumulation in the retinal vascular endothelium and its possible role in preventing early diabetic microvascular damage

Adiponectin (APN), a protein abundantly secreted from adipocytes, has been reported to possess beneficial effects on cardiovascular diseases in association with its accumulation on target organs and cells by binding to T-cadherin. However, little is known about the role of APN in the development of diabetic microvascular complications, such as diabetic retinopathy (DR). Here we investigated the impact of APN on the progression of early retinal vascular damage using a streptozotocin (STZ)-induced diabetic mouse model. Our immunofluorescence results clearly showed T-cadherin-dependent localization of APN in the vascular endothelium of retinal arterioles, which was progressively decreased during the course of diabetes. Such reduction of retinal APN accompanied the early features of DR, represented by increased vascular permeability, and was prevented by glucose-lowering therapy with dapagliflozin, a selective sodium-glucose co-transporter 2 inhibitor. In addition, APN deficiency resulted in severe vascular permeability under relatively short-term hyperglycemia, together with a significant increase in vascular cellular adhesion molecule-1 (VCAM-1) and a reduction in claudin-5 in the retinal endothelium. The present study demonstrated a possible protective role of APN against the development of DR.

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.

Role of Perivascular Adipose Tissue-Derived Adiponectin in Vascular Homeostasis

Studies of adipose tissue biology have demonstrated that adipose tissue should be considered as both passive, energy-storing tissue and an endocrine organ because of the secretion of adipose-specific factors, called adipokines. Adiponectin is a well-described homeostatic adipokine with metabolic properties. It regulates whole-body energy status through the induction of fatty acid oxidation and glucose uptake. Adiponectin also has anti-inflammatory and antidiabetic properties, making it an interesting subject of biomedical studies. Perivascular adipose tissue (PVAT) is a fat depot that is conterminous to the vascular wall and acts on it in a paracrine manner through adipokine secretion. PVAT-derived adiponectin can act on the vascular wall through endothelial cells and vascular smooth muscle cells. The present review describes adiponectin's structure, receptors, and main signaling pathways. We further discuss recent studies of the extent and nature of crosstalk between PVAT-derived adiponectin and endothelial cells, vascular smooth muscle cells, and atherosclerotic plaques. Furthermore, we argue whether adiponectin and its receptors may be considered putative therapeutic targets.

Diabetic fibrosis

Diabetes-associated morbidity and mortality is predominantly due to complications of the disease that may cause debilitating conditions, such as heart and renal failure, hepatic insufficiency, retinopathy or peripheral neuropathy. Fibrosis, the excessive and inappropriate deposition of extracellular matrix in various tissues, is commonly found in patients with advanced type 1 or type 2 diabetes, and may contribute to organ dysfunction. Hyperglycemia, lipotoxic injury and insulin resistance activate a fibrotic response, not only through direct stimulation of matrix synthesis by fibroblasts, but also by promoting a fibrogenic phenotype in immune and vascular cells, and possibly also by triggering epithelial and endothelial cell conversion to a fibroblast-like phenotype. High glucose stimulates several fibrogenic pathways, triggering reactive oxygen species generation, stimulating neurohumoral responses, activating growth factor cascades (such as TGF-β/Smad3 and PDGFs), inducing pro-inflammatory cytokines and chemokines, generating advanced glycation end-products (AGEs) and stimulating the AGE-RAGE axis, and upregulating fibrogenic matricellular proteins. Although diabetes-activated fibrogenic signaling has common characteristics in various tissues, some organs, such as the heart, kidney and liver develop more pronounced and clinically significant fibrosis. This review manuscript summarizes current knowledge on the cellular and molecular pathways involved in diabetic fibrosis, discussing the fundamental links between metabolic perturbations and fibrogenic activation, the basis for organ-specific differences, and the promises and challenges of anti-fibrotic therapies for diabetic patients.

AMP-activated protein kinase: A remarkable contributor to preserve a healthy heart against ROS injury

Heart failure is one of the leading causes of death and disability worldwide. Left ventricle remodeling, fibrosis, and ischemia/reperfusion injury all contribute to the deterioration of cardiac function and predispose to the onset of heart failure. Adenosine monophosphate-activated protein kinase (AMPK) is the universally recognized energy sensor which responds to low ATP levels and restores cellular metabolism. AMPK activation controls numerous cellular processes and, in the heart, it plays a pivotal role in preventing onset and progression of disease. Excessive reactive oxygen species (ROS) generation, known as oxidative stress, can activate AMPK, conferring an additional role of AMPK as a redox-sensor. In this review, we discuss recent insights into the crosstalk between ROS and AMPK. We describe the molecular mechanisms by which ROS activate AMPK and how AMPK signaling can further prevent heart failure progression. Ultimately, we review the potential therapeutic approaches to target AMPK for the treatment of cardiovascular disease and prevention of heart failure.

Obesity and Mortality Among Patients Diagnosed With COVID-19: A Systematic Review and Meta-Analysis

Coronavirus disease 2019 (COVID-19) has already raised serious concern globally as the number of confirmed or suspected cases have increased rapidly. Epidemiological studies reported that obesity is associated with a higher rate of mortality in patients with COVID-19. Yet, to our knowledge, there is no comprehensive systematic review and meta-analysis to assess the effects of obesity and mortality among patients with COVID-19. We, therefore, aimed to evaluate the effect of obesity, associated comorbidities, and other factors on the risk of death due to COVID-19. We did a systematic search on PubMed, EMBASE, Google Scholar, Web of Science, and Scopus between January 1, 2020, and August 30, 2020. We followed Cochrane Guidelines to find relevant articles, and two reviewers extracted data from retrieved articles. Disagreement during those stages was resolved by discussion with the main investigator. The random-effects model was used to calculate effect sizes. We included 17 articles with a total of 543,399 patients. Obesity was significantly associated with an increased risk of mortality among patients with COVID-19 (RRadjust: 1.42 (95%CI: 1.24-1.63, p < 0.001). The pooled risk ratio for class I, class II, and class III obesity were 1.27 (95%CI: 1.05-1.54, p = 0.01), 1.56 (95%CI: 1.11-2.19, p < 0.01), and 1.92 (95%CI: 1.50-2.47, p < 0.001), respectively). In subgroup analysis, the pooled risk ratio for the patients with stroke, CPOD, CKD, and diabetes were 1.80 (95%CI: 0.89-3.64, p = 0.10), 1.57 (95%CI: 1.57-1.91, p < 0.001), 1.34 (95%CI: 1.18-1.52, p < 0.001), and 1.19 (1.07-1.32, p = 0.001), respectively. However, patients with obesity who were more than 65 years had a higher risk of mortality (RR: 2.54; 95%CI: 1.62-3.67, p < 0.001). Our study showed that obesity was associated with an increased risk of death from COVID-19, particularly in patients aged more than 65 years. Physicians should aware of these risk factors when dealing with patients with COVID-19 and take early treatment intervention to reduce the mortality of COVID-19 patients.

Increased vascular permeability and severe renal tubular damage after ischemia-reperfusion injury in mice lacking adiponectin or T-cadherin

Adiponectin (APN) is a circulating protein specifically produced by adipocytes. Native APN specifically binds to T-cadherin, a glycosylphosphatidylinositol-anchored protein, mediating the exosome-stimulating effects of APN in endothelial, muscle, and mesenchymal stem cells. It was previously reported that APN has beneficial effects on kidney diseases, but the role of T-cadherin has not been clarified yet. Here, our immunofluorescence study indicated the existence of both T-cadherin and APN protein in pericytes, subsets of tissue-resident mesenchymal stem/progenitor cells positive for platelet-derived growth factor receptor β (PDGFRβ), surrounding peritubular capillaries. In an acute renal ischemia-reperfusion (I/R) model, T-cadherin-knockout (Tcad-KO) mice, similar to APN-KO mice, exhibited the more progressive phenotype of renal tubular damage and increased vascular permeability than wild-type mice. In addition, in response to I/R-injury, the renal PDGFRβ-positive cell area increased in wild-type mice, but opposingly decreased in both Tcad-KO and APN-KO mice, suggesting severe pericyte loss. Mouse primary pericytes also expressed T-cadherin. APN promoted exosome secretion in a T-cadherin-dependent manner. Such exosome production from pericytes may play an important role in maintaining the capillary network and APN-mediated inhibition of renal tubular injury. In summary, our study suggested that APN protected the kidney in an acute renal injury model by binding to T-cadherin.NEW & NOTEWORTHY In the kidney, T-cadherin-associated adiponectin protein existed on peritubular capillary pericytes. In an acute renal ischemia-reperfusion model, deficiency of adiponectin or T-cadherin exhibited the more progressive phenotype of renal tubular damage and increased vascular permeability, accompanied by severe pericyte loss. In vitro, adiponectin promoted exosome secretion from mouse primary pericytes in a T-cadherin-dependent manner. Adiponectin plays an important role in maintaining the capillary network and amelioration of renal tubular injury by binding to T-cadherin.

PDGFRb+ mesenchymal cells, but not NG2+ mural cells, contribute to cardiac fat

Understanding cellular origins of cardiac adipocytes (CAs) can offer important implications for the treatment of fat-associated cardiovascular diseases. Here, we perform lineage tracing studies by using various genetic models and find that cardiac mesenchymal cells (MCs) contribute to CAs in postnatal development and adult homeostasis. Although PDGFRa⁺ and PDGFRb⁺ MCs both give rise to intramyocardial adipocytes, PDGFRb⁺ MCs are demonstrated to be the major source of intramyocardial adipocytes. Moreover, we find that PDGFRb⁺ cells are heterogenous, as PDGFRb is expressed not only in pericytes and smooth muscle cells (SMCs) but also in some subendocardial, pericapillary, or adventitial PDGFRa⁺ fibroblasts. Dual-recombinase-mediated intersectional genetic lineage tracing reveals that PDGFRa⁺PDGFRb⁺ double-positive periendothelial fibroblasts contribute to intramyocardial adipocytes. In contrast, SMCs and NG2⁺ pericytes do not contribute to CAs. These in vivo findings demonstrate that PDGFRb⁺ MCs, but not NG2⁺ coronary vascular mural cells, are the major source of intramyocardial adipocytes.

Cardiac dysfunction after preeclampsia; an overview of pro- and anti-fibrotic circulating effector molecules

Preeclampsia (PE) is strongly associated with heart failure (HF) later in life. The aberrant cardiac remodelling is likely initiated or amplified during preeclamptic pregnancy. Aberrant remodelling often persists after delivery and is known to relate strongly to cardiac fibrosis. This review provides an overview of pro- and anti- fibrotic circulating effector molecules that are involved in cardiac fibrosis and their association with PE. Women with PE complicated pregnancies show increased ANG-II sensitivity and elevated levels of the pro-fibrotic factors IL-6, TNF-α, TGs and FFAs compared to uncomplicated pregnancies. In the postpartum period, PE pregnancies compared to uncomplicated pregnancies have increased ANG-II sensitivity, elevated levels of the pro-fibrotic factors IL-6, TNF-α, LDL cholesterol and leptin, as well as decreased levels of the anti-fibrotic factor adiponectin. The review revealed several profibrotic molecules that associate to cardiac fibrosis during and after PE. The role that these fibrotic factors have on the heart during and after PE may improve the understanding of the link between PE and HF. Furthermore they may provide insight into the pathways in which the relation between both diseases can be understood as potential mechanisms which interfere in the process of cardiovascular disease (CVD). Unravelling the molecular mechanism and pathways involved might bring the diagnostic and therapeutic abilities of those factors a step closer.

Obesity and Mortality Among Patients Diagnosed With COVID-19: Results From an Integrated Health Care Organization

BACKGROUND

Obesity, race/ethnicity, and other correlated characteristics have emerged as high-profile risk factors for adverse coronavirus disease 2019 (COVID-19)-associated outcomes, yet studies have not adequately disentangled their effects.

OBJECTIVE

To determine the adjusted effect of body mass index (BMI), associated comorbidities, time, neighborhood-level sociodemographic factors, and other factors on risk for death due to COVID-19.

DESIGN

Retrospective cohort study.

SETTING

Kaiser Permanente Southern California, a large integrated health care organization.

PATIENTS

Kaiser Permanente Southern California members diagnosed with COVID-19 from 13 February to 2 May 2020.

MEASUREMENTS

Multivariable Poisson regression estimated the adjusted effect of BMI and other factors on risk for death at 21 days; models were also stratified by age and sex.

RESULTS

Among 6916 patients with COVID-19, there was a J-shaped association between BMI and risk for death, even after adjustment for obesity-related comorbidities. Compared with patients with a BMI of 18.5 to 24 kg/m², those with BMIs of 40 to 44 kg/m² and greater than 45 kg/m² had relative risks of 2.68 (95% CI, 1.43 to 5.04) and 4.18 (CI, 2.12 to 8.26), respectively. This risk was most striking among those aged 60 years or younger and men. Increased risk for death associated with Black or Latino race/ethnicity or other sociodemographic characteristics was not detected.

LIMITATION

Deaths occurring outside a health care setting and not captured in membership files may have been missed.

CONCLUSION

Obesity plays a profound role in risk for death from COVID-19, particularly in male patients and younger populations. Our capitated system with more equalized health care access may explain the absence of effect of racial/ethnic and socioeconomic disparities on death. Our data highlight the leading role of severe obesity over correlated risk factors, providing a target for early intervention.

PRIMARY FUNDING SOURCE

Roche-Genentech.

Adiponectin in heart failure

The adipose tissue, apart from storing energy, plays a role of an endocrine organ. One of the most important adipokines secreted by adipose tissue is adiponectin, which is also produced by cardiomyocytes and connective tissue cells within the heart. Adiponectin is known for its beneficial effect on the metabolism and cardiovascular system and its low level is a factor of development of many cardiovascular diseases. Paradoxically, in the course of heart failure, adiponectin level gradually increases with the severity of the disease and higher adiponectin level is a factor of poor prognosis. As a result, there is a growing interest in adiponectin as a marker of heart failure progression and a predictor of prognosis in the course of this disease.

Downregulation of PPARα during Experimental Left Ventricular Hypertrophy Is Critically Dependent on Nox2 NADPH Oxidase Signalling

Pressure overload-induced left ventricular hypertrophy (LVH) is initially adaptive but ultimately promotes systolic dysfunction and chronic heart failure. Whilst underlying pathways are incompletely understood, increased reactive oxygen species generation from Nox2 NADPH oxidases, and metabolic remodelling, largely driven by PPARα downregulation, are separately implicated. Here, we investigated interaction between the two as a key regulator of LVH using in vitro, in vivo and transcriptomic approaches. Phenylephrine-induced H9c2 cardiomyoblast hypertrophy was associated with reduced PPARα expression and increased Nox2 expression and activity. Pressure overload-induced LVH and systolic dysfunction induced in wild-type mice by transverse aortic constriction (TAC) for 7 days, in association with Nox2 upregulation and PPARα downregulation, was enhanced in PPARα-/- mice and prevented in Nox2-/- mice. Detailed transcriptomic analysis revealed significantly altered expression of genes relating to PPARα, oxidative stress and hypertrophy pathways in wild-type hearts, which were unaltered in Nox2-/- hearts, whilst oxidative stress pathways remained dysregulated in PPARα-/- hearts following TAC. Network analysis indicated that Nox2 was essential for PPARα downregulation in this setting and identified preferential inflammatory pathway modulation and candidate cytokines as upstream Nox2-sensitive regulators of PPARα signalling. Together, these data suggest that Nox2 is a critical driver of PPARα downregulation leading to maladaptive LVH.

Mechanisms linking adipose tissue inflammation to cardiac hypertrophy and fibrosis

Adipose tissue is classically recognized as the primary site of lipid storage, but in recent years has garnered appreciation for its broad role as an endocrine organ comprising multiple cell types whose collective secretome, termed as adipokines, is highly interdependent on metabolic homeostasis and inflammatory state. Anatomical location (e.g. visceral, subcutaneous, epicardial etc) and cellular composition of adipose tissue (e.g. white, beige, and brown adipocytes, macrophages etc.) also plays a critical role in determining its response to metabolic state, the resulting secretome, and its potential impact on remote tissues. Compared with other tissues, the heart has an extremely high and constant demand for energy generation, of which most is derived from oxidation of fatty acids. Availability of this fatty acid fuel source is dependent on adipose tissue, but evidence is mounting that adipose tissue plays a much broader role in cardiovascular physiology. In this review, we discuss the impact of the brown, subcutaneous, and visceral white, perivascular (PVAT), and epicardial adipose tissue (EAT) secretome on the development and progression of cardiovascular disease (CVD), with a particular focus on cardiac hypertrophy and fibrosis.

Effect of fish oil on circulating asymmetric dimethylarginine and adiponectin in overweight or obese patients with atrial fibrillation

Obesity and adipose-derived peptides might be involved in the pathogenesis of atrial fibrillation (AF). Adiponectin plays a major role in the modulation of several metabolic pathways, and asymmetric dimethylarginine (ADMA) has been suggested to be predictive of AF and associated adverse events. The aim of this study was to investigate the effect of fish oil supplementation on circulating adiponectin and ADMA in overweight or obese patients with persistent AF. In this randomized, double-blind, placebo-controlled trial, 80 overweight or obese (body mass index (BMI) ≥ 25 kg/m2) patients with persistent AF were randomly assigned to two groups to receive either 2 g/day fish oil or placebo, for 8 weeks. Serum levels of adiponectin and ADMA, and anthropometric indexes were measured. This study showed that serum adiponectin concentrations increased significantly following fish oil supplementation compared with the placebo group (13.15 ± 7.33 vs. 11.88 ± 6.94 µg/ml; p = .026). A significant reduction was also observed in serum ADMA levels in the fish oil compared with the placebo group following the intervention (0.6 ± 0.13 vs. 0.72 ± 0.15 µmol/L; p = .001). The changes in serum adiponectin and ADMA concentrations remained significant after adjustments for baseline values, age, sex, and changes of BMI and waist circumference (p = .011 and p = .001, respectively). In conclusion,  8 weeks supplementation with fish oil increased serum adiponectin and decreased ADMA concentrations in overweight or obese patients with persistent AF. As adiponectin and ADMA are suggested to be involved in many pathways associated with AF, the current findings might be promising in the clinical management of this disease, an issue that needs further investigations.

MicroRNA 27b promotes cardiac fibrosis by targeting the FBW7/Snail pathway

Our study aspires to understand the impact of miR-27b on myocardial fibrosis as well as its functional mechanism. 12 days post the ligation of coronary artery in rats, the expression of miR-27b in the peri-infarction region was elevated. Treating cultivated rat neonatal cardiac fibroblasts (CFs) with angiotensin II (AngII) also enhanced the miR-27b expression. Forced expression of miR-27b promoted the proliferation and collagen production in rat neonatal CFs, as revealed by cell counting, MTT assay, and quantitative reverse transcription-polymerase chain reaction. FBW7 was found to be the miR-27b's target since the overexpression of miR-27b reduced the transcriptional level of FBW7. The enhanced expression of FBW7 protein abrogated the effects of miR-27b in cultured CFs, while the siRNA silence of FBW7 promoted the pro-fibrosis activity of AngII. As to the mechanism, we found that the expression of FBW7 led to the degradation of Snail, which is an important regulator of cardiac epithelial-mesenchymal transitions. Importantly, inhibition of miR-27b abrogated the coronary artery ligation (CAL) induced cardiac fibrosis in vivo, suggesting that it might be a potential target for the treatment of fibrosis associated cardiac diseases.

C‑type natriuretic peptide prevents angiotensin II‑induced atrial connexin 40 and 43 dysregulation by activating AMP‑activated kinase signaling

C‑type natriuretic peptide (CNP), from the family of natriuretic peptides (NPs), has been shown to induce antihypertrophic and antifibrotic effects in cardiomyocytes. However, the roles of CNP in the atrial dysregulation of connexin (Cx)40 and Cx43 remain to be elucidated. The present study aimed to investigate the effects of CNP on angiotensin (Ang) II‑induced Cx40 and Cx43 dysregulation in isolated perfused beating rat left atria. A rat isolated perfused beating atrial model was used and the protein levels were determined via western blotting. Ang II significantly upregulated NF‑κB, activator protein‑1, transforming growth factor‑β1 (TGF‑β1), collagen I and matrix metalloproteinase 2, leading to atrial fibrosis, and downregulated expression of Cx40 and Cx43. The changes in Cx40 and Cx43 induced by Ang II were abolished by CNP through upregulation of phosphorylated AMP‑activated kinase a1 (AMPK) and downregulation of TGF‑β1. The effects of CNP on AMPK and TGF‑β1 levels were inhibited by KT5823 and pertussis toxin, inhibitors of protein kinase G (PKG) and NP receptor type C (NPR‑C), respectively. Thus, CNP can prevent Ang II‑induced dysregulation of Cx40 and Cx43 through activation of AMPK via the CNP‑PKG and CNP‑NPR‑C pathways in isolated beating rat atria. The present findings suggested that CNP may be therapeutically useful for clinical conditions involving cardiac dysregulation of Cx expression‑related diseases.

Adiponectin, a unique adipocyte-derived factor beyond hormones

Visceral fat accumulation has a marked impact on atherosclerotic cardiovascular diseases and metabolic syndrome clustering diabetes, dyslipidemia, and hypertension. Adiponectin, an adipocyte-derived circulating protein, is a representative adipocytokine and uniquely possesses two major properties: 1) its circulating concentration is approximately 3-6 orders of magnitude greater than ordinary hormones and cytokines; 2) its concentration inversely correlates with body fat mass despite its adipocyte-specific production. Low serum levels of adiponectin correlate with cardiometabolic diseases. Extensive experimental evidence has demonstrated that adiponectin possesses multiple properties, such as anti-atherosclerotic, anti-diabetic, and anti-inflammatory activities. It has been shown to play a central role against the development of metabolic syndrome and its complications. However, even approximately 25 years after its discovery, the properties of adiponectin, including how and why it exerts multiple beneficial effects on various tissues and/or organs, remain unclear. Furthermore, the mechanisms responsible for the very high circulating concentrations of adiponectin in the bloodstream have not been elucidated. Several adiponectin-binding partners, such as AdipoR1/2, have been identified, but do not fully explain the multi-functional and beneficial properties of adiponectin. Recent advances in adiponectin research may resolve these issues. Adiponectin binds to and covers cell surfaces with T-cadherin, a unique glycosylphosphatidylinositol (GPI)-anchored cadherin. The adiponectin/T-cadherin complex enhances exosomal production and release, excreting cell-toxic products from cells, particularly in the vasculature. In this review, we discuss adiponectin and the role of the adiponectin/T-cadherin system in the maintenance of whole body homeostasis and cardiovascular protection.

CTRP9 Ameliorates Atrial Inflammation, Fibrosis, and Vulnerability to Atrial Fibrillation in Post-Myocardial Infarction Rats

Background

Inflammation and fibrosis play an important role in the pathogenesis of atrial fibrillation (AF) after myocardial infarction (MI). CTRP9 (C1q/tumor necrosis factor‐related protein‐9) as a secreted glycoprotein can reverse left ventricle remodeling post‐MI, but its effects on MI‐induced atrial inflammation, fibrosis, and associated AF are unknown.

Methods and Results

MI model rats received adenoviral supplementation of CTRP9 (Ad‐CTRP9) by jugular‐vein injection. Cardiac function, inflammatory, and fibrotic indexes and related signaling pathways, electrophysiological properties, and AF inducibility of atria in vivo and ex vivo were detected in 3 or 7 days after MI. shCTRP9 (short hairpin CTRP9) and shRNA were injected into rat and performed similar detection at day 5 or 10. Adverse atrial inflammation and fibrosis, cardiac dysfunction were induced in both MI and Ad‐GFP (adenovirus‐encoding green fluorescent protein)+MI rats. Systemic CTRP9 treatment improved cardiac dysfunction post‐MI. CTRP9 markedly ameliorated macrophage infiltration and attenuated the inflammatory responses by downregulating interleukin‐1β and interleukin‐6, and upregulating interleukin‐10, in 3 days post‐MI; depressed left atrial fibrosis by decreasing the expressions of collagen types I and III, α‐SMA, and transforming growth factor β1 in 7 days post‐MI possibly through depressing the Toll‐like receptor 4/nuclear factor‐κB and Smad2/3 signaling pathways. Electrophysiologic recordings showed that increased AF inducibility and duration, and prolongation of interatrial conduction time induced by MI were attenuated by CTRP9; moreover, CTRP9 was negatively correlated with interleukin‐1β and AF duration. Downregulation of CTRP9 aggravated atrial inflammation, fibrosis, susceptibility of AF and prolonged interatrial conduction time, without affecting cardiac function.

Conclusions

CTRP9 is effective at attenuating atrial inflammation and fibrosis, possibly via its inhibitory effects on the Toll‐like receptor 4/nuclear factor‐κB and Smad2/3 signaling pathways, and may be an original upstream therapy for AF in early phase of MI.

Effects of Adiponectin on Diastolic Function in Mice Underwent Transverse Aorta Constriction

Diastolic dysfunction is common in various cardiovascular diseases, which could be affected by adiponectin (APN). Nevertheless, the effects of APN on diastolic dysfunction in pressure overload model induced by transverse aorta constriction (TAC) remain to be further elucidated. Here, we demonstrated that treatment of APN attenuated diastolic dysfunction and cardiac hypertrophy in TAC mice. Notably, APN also improved active relaxation of adult cardiomyocytes, increased N2BA/N2B ratios of titin isoform, and reduced collagen type I to type III ratio and lysyl oxidase (Lox) expressions in the myocardial tissue. Moreover, APN supplementation suppressed TAC-induced oxidative stress. In vitro, inhibition of AMPK by compound C (Cpc) abrogated the effect of APN on modulation of titin isoform shift and the anti-hypertrophic effect of APN on cardiomyocytes induced by AngII. In summary, our findings indicate that APN could attenuate diastolic dysfunction in TAC mice, which are at least partially mediated by AMPK pathway.

Epigenetic Regulation of Endothelial-to-Mesenchymal Transition in Chronic Heart Disease

Endothelial-to-mesenchymal transition (EndMT) is a process in which endothelial cells lose their properties and transform into fibroblast-like cells. This transition process contributes to cardiac fibrosis, a common feature of patients with chronic heart failure. To date, no specific therapies to halt or reverse cardiac fibrosis are available, so knowledge of the underlying mechanisms of cardiac fibrosis is urgently needed. In addition, EndMT contributes to other cardiovascular pathologies such as atherosclerosis and pulmonary hypertension, but also to cancer and organ fibrosis. Remarkably, the molecular mechanisms driving EndMT are largely unknown. Epigenetics play an important role in regulating gene transcription and translation and have been implicated in the EndMT process. Therefore, epigenetics might be the missing link in unraveling the underlying mechanisms of EndMT. Here, we review the involvement of epigenetic regulators during EndMT in the context of cardiac fibrosis. The role of DNA methylation, histone modifications (acetylation and methylation), and noncoding RNAs (microRNAs, long noncoding RNAs, and circular RNAs) in the facilitation and inhibition of EndMT are discussed, and potential therapeutic epigenetic targets will be highlighted.

AMPK: a therapeutic target of heart failure-not only metabolism regulation

Heart failure (HF) is a serious disease with high mortality. The incidence of this disease has continued to increase over the past decade. All cardiovascular diseases causing dysfunction of various physiological processes can result in HF. AMP-activated protein kinase (AMPK), an energy sensor, has pleiotropic cardioprotective effects and plays a critical role in the progression of HF. In this review, we highlight that AMPK can not only improve the energy supply in the failing heart by promoting ATP production, but can also regulate several important physiological processes to restore heart function. In addition, we discuss some aspects of some potential clinical drugs which have effects on AMPK activation and may have value in treating HF. More studies, especially clinical trials, should be done to evaluate manipulation of AMPK activation as a potential means of treating HF.

Irisin attenuates angiotensin II-induced cardiac fibrosis via Nrf2 mediated inhibition of ROS/ TGFβ1/Smad2/3 signaling axis

Angiotensin II-related cardiac fibrosis is one of the key pathological changes of the hypertrophied left ventricle in various heart disease. Irisin was recently reported to confer cardio-protective and anti-oxidative effects, while whether it can reverse the renin-angiotensin-aldosterone system(RAAS) activation related(angiotensin II-induced) cardiac fibrosis is unknown. In this study, we found that angiotensin II-induced cardiac dysfunction and fibrotic responses were dampened by irisin treatment in mice. Mechanistically, angiotensin II induced robust ROS generation, which in turn triggered activation of pro-fibrotic TGFβ1-Smad2/3 signaling and subsequent collagen synthesis and fibroblast-myofibroblast transformation in cardiac fibroblasts. In contrast, Irisin treatment suppressed angiotensin II-induced ROS generation, TGFβ1 activation, collagen synthesis and fibroblast-myofibroblast transformation, the effects of which was accompanied by Nrf2 activation and also abolished by a Nrf2 targeted siRNA. Taken together, we here identified irisin as a promising anti-fibrotic therapeutic for angiotensin II-related cardiac fibrosis.

Adiponectin promotes muscle regeneration through binding to T-cadherin

Skeletal muscle has remarkable regenerative potential and its decline with aging is suggested to be one of the important causes of loss of muscle mass and quality of life in elderly adults. Metabolic abnormalities such as obesity were linked with decline of muscle regeneration. On the other hand, plasma levels of adiponectin are decreased in such metabolic conditions. However, plasma levels of adiponectin have been shown to inversely correlate with muscle mass and strength in elderly people especially with chronic heart failure (CHF). Here we have addressed whether adiponectin has some impact on muscle regeneration after cardiotoxin-induced muscle injury in mice. Muscle regeneration was delayed by angiotensin II infusion, mimicking aging and CHF as reported. Adiponectin overexpression in vivo decreased necrotic region and increased regenerating myofibers. Such enhanced regeneration by excess adiponectin was also observed in adiponectin null mice, but not in T-cadherin null mice. Mechanistically, adiponectin accumulated on plasma membrane of myofibers both in mice and human, and intracellularly colocalized with endosomes positive for a multivesicular bodies/exosomes marker CD63 in regenerating myofibers. Purified high-molecular multimeric adiponectin similarly accumulated intracellularly and colocalized with CD63-positive endosomes and enhanced exosome secretion in differentiating C2C12 myotubes but not in undifferentiated myoblasts. Knockdown of T-cadherin in differentiating C2C12 myotubes attenuated both adiponectin-accumulation and adiponectin-mediated exosome production. Collectively, our studies have firstly demonstrated that adiponectin stimulates muscle regeneration through T-cadherin, where intracellular accumulation and exosome-mediated process of adiponectin may have some roles.

AdipoRs- a potential therapeutic target for fibrotic disorders

Introduction: Fibrotic disorders are a leading cause of morbidity and mortality; hence effective treatments are still vigorously sought. AdipoRs (AdipoR1 and Adipo2) are responsible for the antifibrotic effects of adiponectin (APN). APN exerts antifibrotic effects by binding to its receptors. APN concentration and AdipoR expression are closely associated with fibrotic disorders. Decreased AdipoR expression may reduce APN-AdipoR signaling, while the upregulation of AdipoR expression may restore the anti-fibrotic effects of APN. Loss of APN signaling exacerbates fibrosis in vivo and in vitro. Areas covered: We assess the relationship between APN and fibrotic disorders, the structure of receptors for APN and the pathways accounting for APN or its analogs blocking fibrotic disorders. This article also discusses designed APN products and their therapeutic prospects for fibrotic disorders. Expert opinion: AdipoRs have a critical role in blocking fibrosis. The development of small-molecule agonists toward this target represents a valid drug development pathway.

An orally-active adiponectin receptor agonist mitigates cutaneous fibrosis, inflammation and microvascular pathology in a murine model of systemic sclerosis

The hallmarks of systemic sclerosis (SSc) are autoimmunity, microangiopathy and fibrosis. Skin fibrosis is accompanied by attrition of the dermal white adipose tissue layer, and alterations in the levels and function of adiponectin. Since these findings potentially implicate adiponectin in the pathogenesis of SSc, we employed a novel pharmacological approach to augment adiponectin signaling using AdipoRon, an orally active adiponectin receptor agonist. Chronic treatment with AdipoRon significantly ameliorated bleomycin-induced dermal fibrosis in mice. AdipoRon attenuated fibroblast activation, adipocyte-to-myofibroblast transdifferentiation, Th2/Th17-skewed polarization of the immune response, vascular injury and endothelial-to-mesenchymal transition within the lesional skin. In vitro, AdipoRon abrogated profibrotic responses elicited by TGF-β in normal fibroblasts, and reversed the inherently-activated profibrotic phenotype of SSc fibroblasts. In view of these broadly beneficial effects on all three cardinal pathomechanisms underlying the clinical manifestations of SSc, pharmacological augmentation of adiponectin signaling might represent a novel strategy for the treatment of SSc.

Adiponectin attenuates profibrotic extracellular matrix remodeling following cardiac injury by up-regulating matrix metalloproteinase 9 expression in mice

Adiponectin (APN) is a multifunctional adipocytokine that inhibits myocardial fibrosis, dilatation, and left ventricular (LV) dysfunction after myocardial infarction (MI). Coxsackievirus B3 (CVB3) myocarditis is associated with intense extracellular matrix (ECM) remodeling which might progress to dilated cardiomyopathy. Here, we investigated in experimental CVB3 myocarditis whether APN inhibits adverse ECM remodeling following cardiac injury by affecting matrix metalloproteinase (MMP) expression. Cardiac injury was induced by CVB3 infection in APN knockout (APN-KO) and wild-type (WT) mice. Expression and activity of MMPs was quantified by qRT-PCR and zymography, respectively. Activation of protein kinases was assessed by immunoblot. In cardiac myocytes and fibroblasts APN up-regulates MMP-9 expression via activation of 5' adenosine monophosphate-activated protein kinase (AMPK) and extracellular signal-regulated kinase (ERK)1/2 which function as master regulators of inflammation-induced MMP-9 expression. Correspondingly, APN further increased up-regulation of MMP-9 expression triggered by tumor necrosis factor (TNF)α, lipopolysaccharide (LPS) and R-848 in cardiac fibroblasts. In vivo, compared to WT mice cardiac MMP-9 activity and serum levels of carboxy-terminal telopeptide of type I collagen (ICTP) were attenuated in APN-KO mice in subacute (day 7 p.i.) CVB3 myocarditis. Moreover, on day 3 and day 7 post CVB3 infection splenic MMP-9 expression was diminished in APN-KO mice correlating with attenuated myocardial immune cell infiltration in subacute CVB3 myocarditis. These results indicate that APN attenuates adverse cardiac remodeling following cardiac injury by up-regulating MMP-9 expression in cardiac and immune cells. Thus, APN mediates intensified collagen cleavage that might explain inhibition of LV fibrosis and dysfunction.

Adiponectin signaling and its role in bone metabolism

Adiponectin, the most prevalent adipo-cytokine in plasma plays critical metabolic and anti-inflammatory roles is fast emerging as an important molecular target for the treatment of metabolic disorders. Adiponectin action is critical in multiple organs including cardio-vascular system, muscle, liver, adipose tissue, brain and bone. Adiponectin signaling in bone has been a topic of active investigation lately. Human association studies and multiple mice models of gene deletion/modification failed to define a clear cause and effect of adiponectin signaling in bone. The most plausible reason could be the multimeric forms of adiponectin that display differential binding to receptors (adipoR1 and adipoR2) with cell-specific receptor variants in bone. Discovery of small molecule agonist of adipoR1 suggested a salutary role of this receptor in bone metabolism. The downstream signaling of adipoR1 in osteoblasts involves stimulation of oxidative phosphorylation leading to increased differentiation via the likely suppression of wnt inhibitor, sclerostin. On the other hand, the inflammation modulatory effect of adiponectin signaling suppresses the RANKL (receptor activator of nuclear factor κ-B ligand) - to - OPG (osteprotegerin) ratio in osteoblasts leading to the suppression of osteoclastogenic response. This review will discuss the adiponectin signaling and its role in skeletal homeostasis and critically assess whether adipoR1 could be a therapeutic target for the treatment of metabolic bone diseases.