Mature adipocytes and perivascular adipose tissue stimulate vascular smooth muscle cell proliferation: effects of aging and obesity

Atheroma transcriptomics identifies ARNTL as a smooth muscle cell regulator and with clinical and genetic data improves risk stratification

BACKGROUND AND AIMS

The role of vascular smooth muscle cells (SMCs) in atherosclerosis has evolved to indicate causal genetic links with the disease. Single cell RNA sequencing (scRNAseq) studies have identified multiple cell populations of mesenchymal origin within atherosclerotic lesions, including various SMC sub-phenotypes, but it is unknown how they relate to patient clinical parameters and genetics. Here, mesenchymal cell populations in atherosclerotic plaques were correlated with major coronary artery disease (CAD) genetic variants and functional analyses performed to identify SMC markers involved in the disease.

METHODS

Bioinformatic deconvolution was done on bulk microarrays from carotid plaques in the Biobank of Karolinska Endarterectomies (BiKE, n = 125) using public plaque scRNAseq data and associated with patient clinical data and follow-up information. BiKE patients were clustered based on the deconvoluted cell fractions. Quantitative trait loci (QTLs) analyses were performed to predict the effect of CAD associated genetic variants on mesenchymal cell fractions (cfQTLs) and gene expression (eQTLs) in plaques.

RESULTS

Lesions from symptomatic patients had higher fractions of Type 1 macrophages and pericytes, but lower fractions of classical and modulated SMCs compared with asymptomatic ones, particularly females. Presence of diabetes or statin treatment did not affect the cell fraction distribution. Clustering based on plaque cell fractions, revealed three patient groups, with relative differences in their stability profiles and associations to stroke, even during long-term follow-up. Several single nucleotide polymorphisms associated with plaque mesenchymal cell fractions, upstream of the circadian rhythm gene ARNTL were identified. In vitro silencing of ARNTL in human carotid SMCs increased the expression of contractile markers and attenuated cell proliferation.

CONCLUSIONS

This study shows the potential of combining scRNAseq data with vertically integrated clinical, genetic, and transcriptomic data from a large biobank of human plaques, for refinement of patient vulnerability and risk prediction stratification. The study revealed novel CAD-associated variants that may be functionally linked to SMCs in atherosclerotic plaques. Specifically, variants in the ARNTL gene may influence SMC ratios and function, and its role as a regulator of SMC proliferation should be further investigated.

The Implications of Aging on Vascular Health

Vascular aging encompasses structural and functional changes in the vasculature, significantly contributing to cardiovascular diseases, which are the leading cause of death globally. The incidence and prevalence of these diseases increase with age, with most morbidity and mortality attributed to myocardial infarction and stroke. Diagnosing and intervening in vascular aging while understanding the mechanisms behind age-induced vascular phenotypic and pathophysiological alterations offers the potential for delaying and preventing cardiovascular mortality in an aging population. This review delves into various aspects of vascular aging by examining age-related changes in arterial health at the cellular level, including endothelial dysfunction, cellular senescence, and vascular smooth muscle cell transdifferentiation, as well as at the structural level, including arterial stiffness and changes in wall thickness and diameter. We also explore aging-related changes in perivascular adipose tissue deposition, arterial collateralization, and calcification, providing insights into the physiological and pathological implications. Overall, aging induces phenotypic changes that augment the vascular system's susceptibility to disease, even in the absence of traditional risk factors, such as hypertension, diabetes, obesity, and smoking. Overall, age-related modifications in cellular phenotype and molecular homeostasis increase the vulnerability of the arterial vasculature to structural and functional alterations, thereby accelerating cardiovascular risk. Increasing our understanding of these modifications is crucial for success in delaying or preventing cardiovascular diseases. Non-invasive techniques, such as measuring carotid intima-media thickness, pulse wave velocity, and flow-mediated dilation, as well as detecting vascular calcifications, can be used for the early detection of vascular aging. Targeting specific pathological mechanisms, such as cellular senescence and enhancing angiogenesis, holds promise for innovative therapeutic approaches.

Perivascular Adipose Tissue and Uterine Artery Adaptations to Pregnancy

Pregnancy is characterized by longitudinal maternal, physiological adaptations to support the development of a fetus. One of the cardinal maternal adaptations during a healthy pregnancy is a progressive increase in uterine artery blood flow. This facilitates sufficient blood supply for the development of the placenta and the growing fetus. Regional hemodynamic changes in the uterine circulation, such as a vast reduction in uterine artery resistance, are mainly facilitated by changes in uterine artery reactivity and myogenic tone along with remodeling of the uterine arteries. These regional changes in vascular reactivity have been attributed to pregnancy-induced adaptations of cell-to-cell communication mechanisms, with an emphasis on the interaction between endothelial and vascular smooth muscle cells. Perivascular adipose tissue (PVAT) is considered the fourth layer of the vascular wall and contributes to the regulation of vascular reactivity in most vascular beds and most species. This review focuses on mechanisms of uterine artery reactivity and the role of PVAT in pregnancy-induced maternal vascular adaptations, with an emphasis on the uterine circulation.

The Notch-PDGFRβ axis suppresses brown adipocyte progenitor differentiation in early post-natal mice

De novo brown adipogenesis holds potential in combating the epidemics of obesity and diabetes. However, the identity of brown adipocyte progenitor cells (APCs) and their regulation have not been extensively explored. Here, through in vivo lineage tracing and mouse modeling, we observed that platelet-derived growth factor receptor beta (PDGFRβ)+ pericytes give rise to developmental brown adipocytes but not to those in adult homeostasis. By contrast, T-box 18 (TBX18)+ pericytes contribute to brown adipogenesis throughout both developmental and adult stages, though in a depot-specific manner. Mechanistically, Notch inhibition in PDGFRβ+ pericytes promotes brown adipogenesis by downregulating PDGFRβ. Furthermore, inhibition of Notch signaling in PDGFRβ+ pericytes mitigates high-fat, high-sucrose (HFHS)-induced glucose and metabolic impairment in mice during their development and juvenile phases. Collectively, these findings show that the Notch/PDGFRβ axis negatively regulates developmental brown adipogenesis, and its repression promotes brown adipose tissue expansion and improves metabolic health.

Epicardial and Pericoronary Adipose Tissue, Coronary Inflammation, and Acute Coronary Syndromes

Vascular inflammation is recognized as the primary trigger of acute coronary syndrome (ACS). However, current noninvasive methods are not capable of accurately detecting coronary inflammation. Epicardial adipose tissue (EAT) and pericoronary adipose tissue (PCAT), in addition to their role as an energy reserve system, have been found to contribute to the development and progression of coronary artery calcification, inflammation, and plaque vulnerability. They also participate in the vascular response during ischemia, sympathetic stimuli, and arrhythmia. As a result, the evaluation of EAT and PCAT using imaging techniques such as computed tomography (CT), cardiac magnetic resonance (CMR), and nuclear imaging has gained significant attention. PCAT-CT attenuation, which measures the average CT attenuation in Hounsfield units (HU) of the adipose tissue, reflects adipocyte differentiation/size and leukocyte infiltration. It is emerging as a marker of tissue inflammation and has shown prognostic value in coronary artery disease (CAD), being associated with plaque development, vulnerability, and rupture. In patients with acute myocardial infarction (AMI), an inflammatory pericoronary microenvironment promoted by dysfunctional EAT/PCAT has been demonstrated, and more recently, it has been associated with plaque rupture in non-ST-segment elevation myocardial infarction (NSTEMI). Endothelial dysfunction, known for its detrimental effects on coronary vessels and its association with plaque progression, is bidirectionally linked to PCAT. PCAT modulates the secretory profile of endothelial cells in response to inflammation and also plays a crucial role in regulating vascular tone in the coronary district. Consequently, dysregulated PCAT has been hypothesized to contribute to type 2 myocardial infarction with non-obstructive coronary arteries (MINOCA) and coronary vasculitis. Recently, quantitative measures of EAT derived from coronary CT angiography (CCTA) have been included in artificial intelligence (AI) models for cardiovascular risk stratification. These models have shown incremental utility in predicting major adverse cardiovascular events (MACEs) compared to plaque characteristics alone. Therefore, the analysis of PCAT and EAT, particularly through PCAT-CT attenuation, appears to be a safe, valuable, and sufficiently specific noninvasive method for accurately identifying coronary inflammation and subsequent high-risk plaque. These findings are supported by biopsy and in vivo evidence. Although speculative, these pieces of evidence open the door for a fascinating new strategy in cardiovascular risk stratification. The incorporation of PCAT and EAT analysis, mainly through PCAT-CT attenuation, could potentially lead to improved risk stratification and guide early targeted primary prevention and intensive secondary prevention in patients at higher risk of cardiac events.

Genome-Wide Association Study of Pericardial Fat Area in 28 161 UK Biobank Participants

BACKGROUND Pericardial adipose tissue (PAT) is the visceral adipose tissue compartment surrounding the heart. Experimental and observational research has suggested that greater PAT deposition might mediate cardiovascular disease, independent of general or subcutaneous adiposity. We characterize the genetic architecture of adiposity-adjusted PAT and identify causal associations between PAT and adverse cardiac magnetic resonance imaging measures of cardiac structure and function in 28 161 UK Biobank participants. METHODS AND RESULTS The PAT phenotype was extracted from cardiac magnetic resonance images using an automated image analysis tool previously developed and validated in this cohort. A genome-wide association study was performed with PAT area set as the phenotype, adjusting for age, sex, and other measures of obesity. Functional mapping and Bayesian colocalization were used to understand the biologic role of identified variants. Mendelian randomization analysis was used to examine potential causal links between genetically determined PAT and cardiac magnetic resonance-derived measures of left ventricular structure and function. We discovered 12 genome-wide significant variants, with 2 independent sentinel variants (rs6428792, P=4.20×10-9 and rs11992444, P=1.30×10-12) at 2 distinct genomic loci, that were mapped to 3 potentially causal genes: T-box transcription factor 15 (TBX15), tryptophanyl tRNA synthetase 2, mitochondrial (WARS2) and early B-cell factor-2 (EBF2) through functional annotation. Bayesian colocalization additionally suggested a role of RP4-712E4.1. Genetically predicted differences in adiposity-adjusted PAT were causally associated with adverse left ventricular remodeling. CONCLUSIONS This study provides insights into the genetic architecture determining differential PAT deposition, identifies causal links with left structural and functional parameters, and provides novel data about the pathophysiological importance of adiposity distribution.

Changes in subcutaneous white adipose tissue cellular composition and molecular programs underlie glucose intolerance in persons with HIV

Introduction

Subcutaneous adipose tissue (SAT) is a critical regulator of systemic metabolic homeostasis. Persons with HIV (PWH) have an increased risk of metabolic diseases and significant alterations in the SAT immune environment compared with the general population.

Methods

We generated a comprehensive single-cell multi-omic SAT atlas to characterize cellular compositional and transcriptional changes in 59 PWH across a spectrum of metabolic health.

Results

Glucose intolerance was associated with increased lipid-associated macrophages, CD4+ and CD8+ T effector memory cells, and decreased perivascular macrophages. We observed a coordinated intercellular regulatory program which enriched for genes related to inflammation and lipid-processing across multiple cell types as glucose intolerance increased. Increased CD4+ effector memory tissue-resident cells most strongly associated with altered expression of adipocyte genes critical for lipid metabolism and cellular regulation. Intercellular communication analysis demonstrated enhanced pro-inflammatory and pro-fibrotic signaling between immune cells and stromal cells in PWH with glucose intolerance compared with non-diabetic PWH. Lastly, while cell type-specific gene expression among PWH with diabetes was globally similar to HIV-negative individuals with diabetes, we observed substantially divergent intercellular communication pathways.

Discussion

These findings suggest a central role of tissue-resident immune cells in regulating SAT inflammation among PWH with metabolic disease, and underscore unique mechanisms that may converge to promote metabolic disease.

Children who appeared or remained overweight or obese predict a higher follow-up blood pressure and higher risk of hypertension: a 6-year longitudinal study in Yantai, China

Few longitudinal studies have examined the effect of weight status change on blood pressure change over time and incidence of hypertension among Chinese children. The longitudinal study enrolled 17,702 Chinese children aged 7 years in Yantai in 2014 as baseline, with a continuous 5 years of follow-up to 2019. Generalized estimating equation model was fitted to examine the main and interaction effects of weight status change and time with blood pressure and the incidence of hypertension. Compared with the participants who remained normal weight, the participants who remained overweight or obese had higher systolic blood pressure (SBP) (β = 2.89, p < 0.001) and diastolic blood pressure (DBP) (β = 1.79, p < 0.001). Significant interactions were identified between weight status change and time with SBP (χ2interaction = 697.77, p < 0.001) and DBP (χ2interaction = 270.49, p < 0.001). The odds ratio (OR) and 95% confidence interval (CI) of hypertension were 1.70 (1.59-1.82) for participants who appeared overweight or obese, 2.26 (2.14-2.40) for participants who remained overweight or obese, compared with the participants who remained normal weight. Those who switched from overweight or obesity to normal weight had almost the same risk of developing hypertension (OR = 1.13, 95% CI: 1.02 to 1.26) as children who remained normal weight. Children who appeared or remained overweight or obese predict a higher follow-up blood pressure and higher risk of hypertension, whereas losing weight could reduce blood pressure and the risk of hypertension. Children who appeared or remained overweight or obese predict a higher follow-up blood pressure and higher risk of hypertension, whereas losing weight could reduce blood pressure and the risk of hypertension.

The Notch-Pdgfrβ axis suppresses brown adipocyte progenitor differentiation in early postnatal mice

De novo brown adipogenesis holds potential in combating the epidemics of obesity and diabetes. However, the identity of brown adipocyte progenitor cells (APCs) and their regulation have not been extensively studied. Here through in vivo lineage tracing, we observed that PDGFRβ+ pericytes give rise to developmental brown adipocytes, but not to those in adult homeostasis. In contrast, TBX18+ pericytes contribute to brown adipogenesis throughout both developmental and adult stages, though in a depot-specific manner. Mechanistically, Notch inhibition in PDGFRβ+ pericytes promotes brown adipogenesis through the downregulation of PDGFRβ. Furthermore, inhibition of Notch signaling in PDGFRβ+ pericytes mitigates HFHS (high-fat, high-sucrose) induced glucose and metabolic impairment in both developmental and adult stages. Collectively, these findings show that the Notch/PDGFRβ axis negatively regulates developmental brown adipogenesis, and its repression promotes brown adipose tissue expansion and improves metabolic health.

Highlights

PDGFRβ+ pericytes act as an essential developmental brown APC.TBX18+ pericytes contribute to brown adipogenesis in a depot-specific manner.Inhibiting Notch-Pdgfrβ axis promotes brown APC adipogenesis.Enhanced postnatal brown adipogenesis improves metabolic health in adult stage.

Role of Chemerin and Perivascular Adipose Tissue Characteristics on Cardiovascular Risk Assessment by Arterial Stiffness Markers in Patients with Morbid Obesity

BACKGROUND AND OBJECTIVE

The development of arterial stiffness (AS) in obesity is a multifactorial and complex process. The pleomorphic actions of adipokines and their local activity in perivascular adipose tissue (PVAT) are potential modulators of AS appearance and progression. We aimed to assess the correlations between two adipokines (chemerin, adiponectin), PVAT morphological changes (adipocyte size, blood vessel wall thickness) and AS parameters in the special subgroup of patients with morbid obesity.

MATERIAL AND METHODS

We enrolled 25 patients with morbid obesity and 25 non-obese patients, who were age- and gender-matched, untreated for cardiovascular risk factors, and admitted to hospital for laparoscopic surgical procedures (bariatric surgery for morbid obesity and non-inflammatory benign pathology surgery for non-obese patients). Before the surgical procedures, we evaluated demographic and anthropometric data and biochemical parameters including the studied adipokines. Arterial stiffness was evaluated using a Medexpert ArteriographTM TL2 device. In both groups, adipocyte size and vascular wall thickness as well as local adiponectin activity were analyzed in PVAT from intraoperative biopsies.

RESULTS

In our study, adiponectin (p = 0.0003), chemerin (p = 0.0001) and their ratio (p = 0.005) had statistically significant higher mean values in patients with morbid obesity compared to normal-weight patients. In patients with morbid obesity there were significant correlations between chemerin and AS parameters such as aortic pulse wave velocity (p = 0.006) and subendocardial viability index (p = 0.009). In the same group adipocyte size was significantly correlated with another AS parameter, namely, aortic systolic blood pressure (p = 0.030). In normal-weight patients, blood vessel wall thickness positively correlated with AS parameters such as brachial (p = 0.023) and aortic augmentation index (p = 0.023). An important finding was the negative adipoR1 and adipoR2 immunoexpression in PVAT adipocytes of patients with morbid obesity. Additionally, we found significant correlations between blood vessel wall thickness and blood fasting glucose (p < 0.05) in both groups.

CONCLUSIONS

Chemerin and adipocyte size could be predictive biomarkers for AS in patients with morbid obesity. Given the small number of patients included, our results need further validation.

Endothelial Nitric Oxide Synthase in the Perivascular Adipose Tissue

Perivascular adipose tissue (PVAT) is a special type of ectopic fat depot that adheres to most vasculatures. PVAT has been shown to exert anticontractile effects on the blood vessels and confers protective effects against metabolic and cardiovascular diseases. PVAT plays a critical role in vascular homeostasis via secreting adipokine, hormones, and growth factors. Endothelial nitric oxide synthase (eNOS; also known as NOS3 or NOSIII) is well-known for its role in the generation of vasoprotective nitric oxide (NO). eNOS is primarily expressed, but not exclusively, in endothelial cells, while recent studies have identified its expression in both adipocytes and endothelial cells of PVAT. PVAT eNOS is an important player in the protective role of PVAT. Different studies have demonstrated that, under obesity-linked metabolic diseases, PVAT eNOS may be even more important than endothelium eNOS in obesity-induced vascular dysfunction, which may be attributed to certain PVAT eNOS-specific functions. In this review, we summarized the current understanding of eNOS expression in PVAT, its function under both physiological and pathological conditions and listed out a few pharmacological interventions of interest that target eNOS in PVAT.

Different Roles of Stem/Progenitor Cells in Vascular Remodeling

Significance: Since the discovery of vascular stem cells, there has been considerable advancement in comprehending the nature and functions of these cells. Due to their differentiation potential to repair endothelial cells and to participate in lesion formation during vascular remodeling, it is crucial to elucidate vascular stem cell behaviors and the mechanisms underlying this process, which could provide new chances for the design of clinical therapeutic application of stem cells. Recent Advances: Over the past decades, major progress has been made on progenitor/vascular stem cells in the field of cardiovascular research. Vascular stem cells are mostly latent in their niches and can be bioactivated in response to damage and get involved in endothelial repair and smooth muscle cell aggregation to generate neointima. Accumulating evidence has been shown recently, using genetic lineage tracing mouse models, to particularly provide solutions to the nature of vascular stem cells and to monitor both cell migration and the process of differentiation during physiological angiogenesis and in vascular diseases. Critical Issues: This article reviews and summarizes the current research progress of vascular stem cells in this field and highlights future prospects for stem cell research in regenerative medicine. Future Directions: Despite recent advances and achievements of stem cells in cardiovascular research, the nature and cell fate of vascular stem cells remain elusive. Further comprehensive studies using new techniques including genetic cell lineage tracing and single-cell RNA sequencing are essential to fully illuminate the role of stem cells in vascular development and diseases. Antioxid. Redox Signal. 35, 192-203.

Harnessing adipose stem cell diversity in regenerative medicine

Since the first isolation of mesenchymal stem cells from lipoaspirate in the early 2000s, adipose tissue has been a darling of regenerative medicine. It is abundant, easy to access, and contains high concentrations of stem cells (ADSCs) exhibiting multipotency, proregenerative paracrine signaling, and immunomodulation-a winning combination for stem cell-based therapeutics. While basic science, preclinical and clinical findings back up the translational potential of ADSCs, the vast majority of these used cells from a single location-subcutaneous abdominal fat. New data highlight incredible diversity in the adipose morphology and function in different anatomical locations or depots. Even in isolation, ADSCs retain a memory of this diversity, suggesting that the optimal adipose source material for ADSC isolation may be application specific. This review discusses our current understanding of the heterogeneity in the adipose organ, how that heterogeneity translates into depot-specific ADSC characteristics, and how atypical ADSC populations might be harnessed for regenerative medicine applications. While our understanding of the breadth of ADSC heterogeneity is still in its infancy, clear trends are emerging for application-specific sourcing to improve regenerative outcomes.

A new approach to cardiac fat volume assessment and the correlation with coronary artery calcification

BACKGROUND

Coronary artery disease (CAD) is the foremost cause of death in the most developed societies. Plaque formation in epicardial coronary arteries and ensuing inflammation are a known pathophysiologic factor of CAD.

OBJECTIVES

We aimed to separately and simultaneously evaluate the correlation between pericardial fat pad volume and overall peri-coronary epicardial adipose tissue (EAT) thickness with coronary calcium score (CCS) to improve risk stratification of CAD.

METHODS

We retrospectively reviewed patients who underwent a non-invasive contrast-enhanced coronary multidetector CT (MDCT) angiography. Peri-coronary EAT thickness, pericardial fat pad volume and CCS were obtained by an expert radiologist from the patients coronary multidetector CT (MDCT) angiography.

RESULTS

We included 141 symptomatic patients (86 men, 55 women) with an average age of 53.53 ± 12.92. An increment of overall peri-coronary EAT thickness (1/3 × (left anterior descending artery (LAD) + left circumflex artery (LCx) + right coronary artery (RCA)) was associated with a 49% increase in the odds for the presence of coronary artery calcification (CAC) (P = 0.004). Significant predictability of peri-coronary EAT-average was seen in diagnosing calcified plaque. Pericardial fat pad volume was positively correlated with overall peri-coronary EAT thickness in age and body mass index (BMI)-adjusted linear regression models, (P < 0.001).

CONCLUSION

Our results amplify previous idea that peri-coronary EAT and pericardial fat pad volume might act as useful markers and better indicators of CCS based on Agatston score in comparison with BMI or body weight in order to reveal subsequent CADs.

Role of Inflammation in Vascular Disease-Related Perivascular Adipose Tissue Dysfunction

Perivascular adipose tissue (PVAT) is the connective tissue around most blood vessels throughout the body. It provides mechanical support and maintains vascular homeostasis in a paracrine/endocrine manner. Under physiological conditions, PVAT has anti-inflammatory effects, improves free fatty acid metabolism, and regulates vasodilation. In pathological conditions, PVAT is dysfunctional, secretes many anti-vasodilator factors, and participates in vascular inflammation through various cells and mediators; thus, it causes dysfunction involving vascular smooth muscle cells and endothelial cells. Inflammation is an important pathophysiological event in many vascular diseases, such as vascular aging, atherosclerosis, and hypertension. Therefore, the pro-inflammatory crosstalk between PVAT and blood vessels may comprise a novel therapeutic target for the prevention and treatment of vascular diseases. In this review, we summarize findings concerning PVAT function and inflammation in different pathophysiological backgrounds, focusing on the secretory functions of PVAT and the crosstalk between PVAT and vascular inflammation in terms of vascular aging, atherosclerosis, hypertension, diabetes mellitus, and other diseases. We also discuss anti-inflammatory treatment for potential vascular diseases involving PVAT.

Targeting perivascular and epicardial adipose tissue inflammation: therapeutic opportunities for cardiovascular disease

Major shifts in human lifestyle and dietary habits toward sedentary behavior and refined food intake triggered steep increase in the incidence of metabolic disorders including obesity and Type 2 diabetes. Patients with metabolic disease are at a high risk of cardiovascular complications ranging from microvascular dysfunction to cardiometabolic syndromes including heart failure. Despite significant advances in the standards of care for obese and diabetic patients, current therapeutic approaches are not always successful in averting the accompanying cardiovascular deterioration. There is a strong relationship between adipose inflammation seen in metabolic disorders and detrimental changes in cardiovascular structure and function. The particular importance of epicardial and perivascular adipose pools emerged as main modulators of the physiology or pathology of heart and blood vessels. Here, we review the peculiarities of these two fat depots in terms of their origin, function, and pathological changes during metabolic deterioration. We highlight the rationale for pharmacological targeting of the perivascular and epicardial adipose tissue or associated signaling pathways as potential disease modifying approaches in cardiometabolic syndromes.

Perivascular Adipose Tissue Regulates Vascular Function by Targeting Vascular Smooth Muscle Cells

Adipose tissues are present at multiple locations in the body. Most blood vessels are surrounded with adipose tissue which is referred to as perivascular adipose tissue (PVAT). Similarly to adipose tissues at other locations, PVAT harbors many types of cells which produce and secrete adipokines and other undetermined factors which locally modulate PVAT metabolism and vascular function. Uncoupling protein-1, which is considered as a brown fat marker, is also expressed in PVAT of rodents and humans. Thus, compared with other adipose tissues in the visceral area, PVAT displays brown-like characteristics. PVAT shows a distinct function in the cardiovascular system compared with adipose tissues in other depots which are not adjacent to the vascular tree. Growing and extensive studies have demonstrated that presence of normal PVAT is required to maintain the vasculature in a functional status. However, excessive accumulation of dysfunctional PVAT leads to vascular disorders, partially through alteration of its secretome which, in turn, affects vascular smooth muscle cells and endothelial cells. In this review, we highlight the cross talk between PVAT and vascular smooth muscle cells and its roles in vascular remodeling and blood pressure regulation.

A New Function for Perivascular Adipose Tissue (PVAT): Assistance of Arterial Stress Relaxation

In health, PVAT secretes anti-contractile factors that relax the underlying artery. PVAT’s contributions to vascular function include more than production of vasoactive substances. We hypothesized that PVAT benefits the artery by assisting the function of stress (–induced) relaxation. Thoracic aorta rings from Sprague Dawley rats were mounted in isolated tissue baths with (+) and without (−) PVAT. A cumulative length tension (0–6 grams) was generated. The tension to which the tissue stress relaxed over 30 minutes was recorded; the tension lost was stress relaxation. The presence of PVAT increased the amount of stress relaxation (final tension in mgs; aortic ring −PVAT = 4578 ± 190; aortic ring + PVAT = 2730 ± 274, p < 0.05). PVAT left attached but not encompassing the aorta provided no benefit in cumulative stress relaxation (aortic ring +/− PVAT = 4122 ± 176; p > 0.05 vs −PVAT). A PVAT ring separated from the aorta demonstrated more profound stress relaxation than did the aortic ring itself. Finally, PVAT-assisted stress relaxation was observed in an artery with white fat (superior mesenteric artery) and in aorta from both male and female of another rat strain, the Dahl S rat. Knowledge of this new PVAT function supports PVAT as an essential player in vascular health.

Age-Dependent and -Independent Effects of Perivascular Adipose Tissue and Its Paracrine Activities during Neointima Formation

Cardiovascular risk factors may act by modulating the composition and function of the adventitia. Here we examine how age affects perivascular adipose tissue (PVAT) and its paracrine activities during neointima formation. Aortic tissue and PVAT or primary aortic smooth muscle cells from male C57BL/6JRj mice aged 52 weeks (“middle-aged”) were compared to tissue or cells from mice aged 16 weeks (“adult”). Vascular injury was induced at the carotid artery using 10% ferric chloride. Carotid arteries from the middle-aged mice exhibited smooth muscle de-differentiation and elevated senescence marker expression, and vascular injury further aggravated media and adventitia thickening. Perivascular transplantation of PVAT had no effect on these parameters, but age-independently reduced neointima formation and lumen stenosis. Quantitative PCR analysis revealed a blunted increase in senescence-associated proinflammatory changes in perivascular tissue compared to visceral adipose tissue and higher expression of mediators attenuating neointima formation. Elevated levels of protein inhibitor of activated STAT1 (PIAS1) and lower expression of STAT1- or NFκB-regulated genes involved in adipocyte differentiation, inflammation, and apoptosis/senescence were present in mouse PVAT, whereas PIAS1 was reduced in the PVAT of patients with atherosclerotic vessel disease. Our findings suggest that age affects adipose tissue and its paracrine vascular activities in a depot-specific manner. PIAS1 may mediate the age-independent vasculoprotective effects of perivascular fat.

Epicardial adipose tissue is a predictor of decreased kidney function and coronary artery calcification in youth- and early adult onset type 2 diabetes mellitus

PURPOSE

To examine the association of epicardial and pericardial fat volume (EFV, PFV) with cardiovascular risk factors and kidney function in Native Americans of southwestern heritage with youth and early adult onset type 2 diabetes mellitus (T2DM) versus healthy controls.

METHODS

Using computed tomography, we quantified EFV and PFV in 149 Native Americans (92 women, 57 men), 95 of which had T2DM (38 diagnosed prior to age 20 years). Duration of T2DM, mean carotid arterial mass (AM), coronary artery calcification (CAC), IL-6, and estimated glomerular filtration rate eGFR_cr(CKD-EPI) were measured.

RESULTS

EFV and PFV were associated with BMI (r = 0.37, p < 0.0001; r = 0.26, p = 0.001) and did not differ between onset age-groups and controls (p > 0.05). EFV was associated with AM only in controls (r = 0.51, p < 0.0001). After adjustment for BMI, T2DM duration, HbA1C, age, and sex, EFV was a predictor of CAC and IL-6 concentrations in early adult onset T2DM (β = 0.05 ± 0.02 cm³, p = 0.03; β = 0.05 ± 0.01 pg/ml/cm³, p = 0.002). EFV and PFV were independent predictors of reduced eGFR_cr(CKD-EPI) in the youth onset T2DM group (β = -0.3 ± 0.08 ml/min/cm³, p = 0.001; β = -0.25 ± 0.05 ml/min/cm³, p < 0.0001).

CONCLUSIONS

Epicardial fat volume may be a risk factor for heart disease in individuals with early adult onset T2DM and a predictor of decreased kidney function in individuals with youth onset T2DM.

The Mesenteric Fat and Intestinal Muscle Interface: Creeping Fat Influencing Stricture Formation in Crohn's Disease

Adipose tissue is present in close proximity to various organs in the human body. One prominent example is fat contained in the mesentery that is contiguous with all abdominal digestive organs including the intestine. Despite the fact that mesenteric fat-wrapping around the inflamed gut (so called "creeping fat") was described as a characteristic feature of Crohn's disease (CD) in the early 1930s, the functional implications of creeping fat have received only recent attention. As a potent producer of fatty acids, cytokines, growth factors, and adipokines, creeping fat plays an important role in regulation of immunity and inflammation. Increasing evidence points to a link between creeping fat and intestinal inflammation in CD, where histopathologic evaluation shows a significant association between creeping fat and connective tissue changes in the bowel wall, such as muscular hypertrophy, fibrosis, and stricture formation. In addition, emerging mechanistic data indicate a link between creeping fat, muscularis propria hyperplasia, and stricturing disease. Information on fat-mesenchymal interactions in other organs could provide clues to fill the fundamental knowledge gap on the role of distinct components of creeping fat in intestinal fibrosis and stricture formation. Future studies will provide important new information that in turn could lead to novel therapeutic agents aimed at prevention or treatment of CD-associated fibrosis and stricture formation.

Hydrogen peroxide and nitric oxide induce anticontractile effect of perivascular adipose tissue via renin angiotensin system activation

The perivascular adipose tissue (PVAT) is located around the adventitia, composed primarily by adipocytes, stromal cells, leukocytes, fibroblasts and capillaries. It is well described that PVAT is an important modulator of the vascular tone being considered a biologically active tissue, releasing both vasoconstrictor and vasodilators factors. The literature shows that the anti-contractile effect induced by PVAT may be due to activation of the renin-angiotensin system (RAS).

AIM

Investigate whether the renin-angiotensin system participates in the effect exerted by perivascular adipose tissue on the vascular tone.

METHODS AND RESULTS

For this study we used thoracic aorta from Balb/c mice and performed vascular reactivity, nitric oxide and hydrogen peroxide quantification using selective probes and fluorescence microscopy, immunofluorescence to locate receptors and enzymes involved in this response. Our results demonstrated that perivascular adipose tissue induces an anti-contractile effect in endothelium-independent manner and involves Mas and AT₂ receptors participation with subsequent PI3K/Akt pathway activation. This pathway culminated with nitric oxide and hydrogen peroxide production by neuronal nitric oxide synthase, being hydrogen peroxide most relevant for the anti-contractile effect of perivascular adipose tissue.

CONCLUSION

For the first time in the literature, our results show the presence of Mas and AT₂ receptors, as well as, nitric oxide synthase on perivascular adipose tissue. Furthermore, our results show the involvement of Mas and AT₂ receptors and consequently nitric oxide synthase activation in the anti-contractile effect exerted by perivascular adipose tissue.

Perivascular adipose tissue dysfunction aggravates adventitial remodeling in obese mini pigs via NLRP3 inflammasome/IL-1 signaling pathway

Perivascular adipose tissue (PVAT), a special type of adipose tissue, closely surrounds vascular adventitia and produces numerous bioactive substances to maintain vascular homeostasis. PVAT dysfunction has a crucial role in regulating vascular remodeling, but the exact mechanisms remain unclear. In this study, we investigated whether and how obesity-induced PVAT dysfunction affected adventitia remodeling in early vascular injury stages. Mini pigs were fed a high sugar and fat diet for 6 months to induce metabolic syndrome and obesity. In the mini pigs, left carotid vascular injury was then generated using balloon dilation. Compared with normal mini pigs, obese mini pigs displayed significantly enhanced vascular injury-induced adventitial responses, evidenced by adventitia fibroblast (AF) proliferation and differentiation, and adventitia fibrosis, as well as exacerbated PVAT dysfunction characterized by increased accumulation of resident macrophages, particularly the M1 pro-inflammatory phenotype, increased expression of leptin and decreased expression of adiponectin, and production of pro-inflammatory cytokines interleukin (IL)-1β and IL-18. Primary AFs cultured in PVAT-conditioned medium from obese mini pigs also showed significantly increased proliferation and differentiation. We further revealed that activated nod-like receptor protein 3 (NLRP3) inflammasome and its downstream products, i.e., IL-1 family members such as IL-1β and IL-18 were upregulated in the PVAT of obese mini pigs; PVAT dysfunction was also demonstrated in preadipocytes treated with palmitic acid. Finally, we showed that pretreatment with IL-1 receptor (IL-1R) antagonist or IL-1R knockdown blocked AF proliferation and differentiation in AFs cultured in PVAT-conditioned medium. These results demonstrate that obesity-induced PVAT dysfunction aggravates adventitial remodeling after early vascular injury with elevated AF proliferation and differentiation via activating the NLRP3/IL-1 signaling pathway.

Vascular Oxidative Stress: Impact and Therapeutic Approaches

Oxidative stress has been defined as an imbalance between oxidants and antioxidants and more recently as a disruption of redox signaling and control. It is generally accepted that oxidative stress can lead to cell and tissue injury having a fundamental role in vascular dysfunction. Physiologically, reactive oxygen species (ROS) control vascular function by modulating various redox-sensitive signaling pathways. In vascular disorders, oxidative stress instigates endothelial dysfunction and inflammation, affecting several cells in the vascular wall. Vascular ROS are derived from multiple sources herein discussed, which are prime targets for therapeutic development. This review focuses on oxidative stress in vascular physiopathology and highlights different strategies to inhibit ROS production.

Adipose tissue depots and inflammation: effects on plasticity and resident mesenchymal stem cell function

Adipose tissue (AT) is a highly heterogeneous organ. Beside the heterogeneity associated to different tissue types (white, brown, and 'brite') and its location-related heterogeneity (subcutaneous, visceral, epicardial, and perivascular, etc.), AT composition, structure, and functionality are highly dependent on individual-associated factors. As such, the pro-inflammatory state associated to the presence of obesity and other cardiovascular risk factors (CVRFs) directly affects AT metabolism. Furthermore, the adipose-derived stem cells (ASCs) that reside in the stromal vascular fraction of AT, besides being responsible for most of the plasticity attributed to AT, is an additional source of heterogeneity. Thus, ASCs directly contribute to AT homeostasis, cell renewal, and spontaneous repair. These ASCs share many properties with the bone-marrow mesenchymal stem cells (i.e. potential to differentiate towards multiple tissue lineages, and angiogenic, antiapoptotic, and immunomodulatory properties). Moreover, ASCs show clear advantages in terms of accessibility and quantity of available sample, their easy in vitro expansion, and the possibility of having an autologous source. All these properties point out towards a potential use of ASCs in regenerative medicine. However, the presence of obesity and other CVRFs induces a pro-inflammatory state that directly impacts ASCs proliferation and differentiation capacities affecting their regenerative abilities. The focus of this review is to summarize how inflammation affects the different AT depots and the mechanisms by which these changes further enhance the obesity-associated metabolic disturbances. Furthermore, we highlight the impact of obesity-induced inflammation on ASCs properties and how those effects impair their plasticity.

Visceral adiposity index (VAI), a powerful predictor of incident hypertension in prehypertensives

Prehypertension (defined by The Seventh Report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, JNC-7) is relevant to a higher cardiovascular risk than normotensives. Early intervention in this particular population is essential to avoid progression into hypertension (HTN). This study is to explore whether visceral adiposity index (VAI) can strongly predict the incidence of HTN in community-based prehypertensives. A prospective observational cohort study was conducted from September 2011 to June 2012 in urban communities of Chengdu, Sichuan Province, China. 780 subjects (male 320, female 460) were evaluated on anthropometrical indices, blood pressure, blood samples, brachial-ankle pulse wave velocity, of whom 360 prehypertensives (male 160, female 200) were recruited for a 5-year follow-up. Overall, 97 subjects (male 37, female 60) developed HTN. The risk for developing HTN in the future increases with increasing VAI levels. The OR of the upper quartile is 3.719 (95% CI 1.481-9.338, P = 0.005) after adjusting for confounders. The ROC results reveal that VAI is not considered superior to other indices on account of the significant overlapping confidence intervals. The area under the curves (AUC) of Model 5 (combination of VAI and WC) is significantly higher than BMI, WC and WHR (P < 0.05). The AUC of Model 4 (combination of VAI and BMI) is found to be significantly higher than BMI and WHR (P < 0.05), and is also higher than WC in all subject groups and in the male subgroup, but not in the female subgroup. VAI at baseline is an independent risk factor and early predictor of incident HTN in prehypertensives. The predictive value is not stronger than other traditional obesity indices (BMI, WC and WHR); however, it is superior to the latter by combining VAI and WC. Namely, VAI may help identify individuals at high risk of evolving into HTN in this particular population.

Perivascular Adipose Tissue as a Relevant Fat Depot for Cardiovascular Risk in Obesity

Obesity is associated with increased risk of premature death, morbidity, and mortality from several cardiovascular diseases (CVDs), including stroke, coronary heart disease (CHD), myocardial infarction, and congestive heart failure. However, this is not a straightforward relationship. Although several studies have substantiated that obesity confers an independent and additive risk of all-cause and cardiovascular death, there is significant variability in these associations, with some lean individuals developing diseases and others remaining healthy despite severe obesity, the so-called metabolically healthy obese. Part of this variability has been attributed to the heterogeneity in both the distribution of body fat and the intrinsic properties of adipose tissue depots, including developmental origin, adipogenic and proliferative capacity, glucose and lipid metabolism, hormonal control, thermogenic ability, and vascularization. In obesity, these depot-specific differences translate into specific fat distribution patterns, which are closely associated with differential cardiometabolic risks. The adventitial fat layer, also known as perivascular adipose tissue (PVAT), is of major importance. Similar to the visceral adipose tissue, PVAT has a pathophysiological role in CVDs. PVAT influences vascular homeostasis by releasing numerous vasoactive factors, cytokines, and adipokines, which can readily target the underlying smooth muscle cell layers, regulating the vascular tone, distribution of blood flow, as well as angiogenesis, inflammatory processes, and redox status. In this review, we summarize the current knowledge and discuss the role of PVAT within the scope of adipose tissue as a major contributing factor to obesity-associated cardiovascular risk. Relevant clinical studies documenting the relationship between PVAT dysfunction and CVD with a focus on potential mechanisms by which PVAT contributes to obesity-related CVDs are pointed out.

Transplantation of Normal Adipose Tissue Improves Blood Flow and Reduces Inflammation in High Fat Fed Mice With Hindlimb Ischemia

Background: Fat deposition is associated with peripheral arterial disease. Adipose tissue has recently been implicated in vascular remodeling and angiogenic activity. We hypothesized that the transplantation of adipose tissues from normal mice improves blood flow perfusion and neovascularization in high-fat diet fed mice. Methods: After 14 weeks of high-fat diet (HFD)-fed mice, unilateral hind limb ischemia was performed. Subcutaneous white adipose tissue (WAT) and brown adipose tissue (BAT) fat pads were harvested from normal EGFP mice, and subcutaneously transplanted over the region of the adductor muscles of HFD mice. Blood flow was measured using Laser Doppler Scanner. Vascular density, macrophages infiltration, and macrophage polarization were examined by RT-qPCR, and immunohistochemistry. Results: We found that the transplantation of WAT derived from normal mice improved functional blood flow in HFD-fed mice compared to mice transplanted with BAT and sham-treated mice. WAT transplantation increased the recruitment of pericytes associated with nascent blood vessels, but did not affect capillary formation. Furthermore, transplantation of WAT ameliorated HFD-induced insulin resistance, M2 macrophage predominance and the release of arteriogenic factors in ischemic muscles. Mice receiving WAT also displayed a marked reduction in several proinflammatory cytokines. In contrast, mice transplanted with BAT were glucose intolerant and demonstrated increased IL-6 levels in ischemic muscles. Conclusion: These results indicate that transplantation of adipose tissue elicits improvements in blood perfusion and beneficial effects on systemic glucose homeostasis and could be a promising therapeutic option for the treatment of diabetic peripheral arterial disease.

Periaortic Adipose Tissue Compared With Peribrachial Adipose Tissue Mass as Markers and Possible Modulators of Cardiometabolic Risk

Increased perivascular fat mass contributes to cardiometabolic risk (CMR). High peribrachial adipose tissue (PBAT) associates with insulin resistance independently of established CMR parameters. It is unknown to what extent periaortic adipose tissue (PAAT) may have a similar impact. In 95 participants, precise quantification of total adipose tissue, PBAT, PAAT, visceral adipose tissue (VAT), and liver fat (LF) content was performed by whole-body magnetic resonance imaging. Insulin sensitivity was determined by oral glucose tolerance test and carotid intima-media thickness (cIMT) by high-resolution ultrasound. In univariate analyses, PAAT correlated with PBAT (β = .65, P < .0001). A negative correlation of PAAT (β = -.35, P = .0002) and PBAT (β = -.43, P < .0001) with insulin sensitivity was observed. While in a stepwise forward regression analysis the relationship of PAAT with insulin sensitivity was no longer significant after adjustment for VAT, LF content, and other CMR factors ( P = 0.42), PBAT still correlated with insulin sensitivity ( r² = .35, P = .01). The association between PAAT and cIMT (β = .49, P < .0001) remained significant after adjustment for these variables ( r² = .42, P = .0001). Although PAAT and PBAT strongly correlate, PAAT is not associated with insulin resistance, but with cIMT. Therefore, PAAT and PBAT may act differently as possible modulators of insulin resistance and subclinical atherosclerosis.

Role of Perivascular Adipose Tissue in Health and Disease

Perivascular adipose tissue (PVAT) is cushion of fat tissue surrounding blood vessels, which is phenotypically different from other adipose tissue depots. PVAT is composed of adipocytes and stromal vascular fraction, constituted by different populations of immune cells, endothelial cells, and adipose-derived stromal cells. It expresses and releases an important number of vasoactive factors with paracrine effects on vascular structure and function. In healthy individuals, these factors elicit a net anticontractile and anti-inflammatory paracrine effect aimed at meeting hemodynamic and metabolic demands of specific organs and regions of the body. Pathophysiological situations, such as obesity, diabetes or hypertension, induce changes in its amount and in the expression pattern of vasoactive factors leading to a PVAT dysfunction in which the beneficial paracrine influence of PVAT is shifted to a pro-oxidant, proinflammatory, contractile, and trophic environment leading to functional and structural cardiovascular alterations and cardiovascular disease. Many different PVATs surrounding a variety of blood vessels have been described and exhibit regional differences. Both protective and deleterious influence of PVAT differs regionally depending on the specific vascular bed contributing to variations in the susceptibility of arteries and veins to vascular disease. PVAT therefore, might represent a novel target for pharmacological intervention in cardiovascular disease. © 2018 American Physiological Society. Compr Physiol 8:23-59, 2018.

Role of lipids and intraplaque hypoxia in the formation of neovascularization in atherosclerosis

According to the current paradigm, chronic vascular inflammation plays a central role in the pathogenesis of atherosclerosis. The plaque progression is typically completed with rupture and subsequent acute cardiovascular complications. Previously, the role of adventitial vasa vasorum in atherogenesis was underestimated. However, investigators then revealed that vasa vasorum neovascularization can be observed when no clinical manifestation of atherosclerosis is present. Vasa vasorum is involved in various proatherogenic processes such as intimal accumulation of inflammatory leukocytes, intimal thickening, necrotic core formation, intraplaque haemorrhage, lesion rupture and atherothrombosis. Due to the destabilizing action of the intraplaque microenvironment, lesional vasa vasorum neovessels experience serious defects and abnormalities during development that leads to their immaturity, fragility and leakage. Indeed, intraplaque neovessels are a main cause of intraplaque haemorrhage. Visualization techniques showed that presence of neovascularization/haemorrhage can serve as a good indicator of lesion instability and higher risk of rupture. Vasa vasorum density is a strong predictor of acute cardiovascular events such as sudden death, myocardial infarction and stroke. At present, arterial vasa vasorum neovascularization is under intensive investigation along with development of therapeutic tools focused on the control of formation of vasa vasorum neovessels in order to prevent plaque haemorrhage/rupture and thromboembolism. KEY MESSAGE Neovascularization plays an important role in atherosclerosis, being involved in unstable plaque formation. Presence of neovascularization and haemorrhage indicates plaque instability and risk of rupture. Various imaging techniques are available to study neovascularization.

Methionine-supplemented diet affects the expression of cardiovascular disease-related genes and increases inflammatory cytokines in mice heart and liver

Some important environmental factors that influence the development of cardiovascular diseases (CVD) include tobacco, excess alcohol, and unhealthy diet. Methionine obtained from the diet participates in the synthesis of DNA, proteins, lipids and affects homocysteine levels, which is associated with the elevated risk for CVD development. Therefore, the aim of this study was to investigate the manner in which dietary methionine might affect cellular mechanisms underlying CVD occurrence. Swiss albino mice were fed either control (0.3% DL-methionine), methionine-supplemented (2% DL-methionine), or a methionine-deprived diet (0% DL-methionine) over a 10-week period. The parameters measured included plasma homocysteine concentrations, oxidative stress by reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio, levels of inflammatory cytokines IL-1ß, TNF-α, and IL-6, as well as expression of genes associated with CVD. The levels of apolipoprotein A5 (APOA5), a regulator of plasma triglycerides, were measured. The methionine-supplemented diet increased oxidative stress by lowering the GSH/GSSG ratio in heart tissues and decreased expression of the genes Apob, Ctgf, Serpinb2, Spp1, Il1b, and Sell, but elevated expression of Thbs4, Tgfb2, Ccr1, and Vegfa. Methionine-deprived diet reduced expression of Col3a1, Cdh5, Fabp3, Bax, and Hbegf and increased expression of Sell, Ccl5, Itga2, Birc3, Msr1, Bcl2a1a, Il1r2, and Selp. Methionine-deprived diet exerted pro-inflammatory consequences as evidenced by elevated levels of cytokines IL-1ß, TNF-α, and IL-6 noted in liver. Methionine-supplemented diet increased hepatic IL-6 and cardiac TNF-α. Both methionine supplementation and deprivation lowered hepatic levels of APOA5. In conclusion, data demonstrated that a methionine-supplemented diet modulated important biological processes associated with high risk of CVD development.

Role of Epicardial Adipose Tissue in Health and Disease: A Matter of Fat?

Epicardial adipose tissue (EAT) is a small but very biologically active ectopic fat depot that surrounds the heart. Given its rapid metabolism, thermogenic capacity, unique transcriptome, secretory profile, and simply measurability, epicardial fat has drawn increasing attention among researchers attempting to elucidate its putative role in health and cardiovascular diseases. The cellular crosstalk between epicardial adipocytes and cells of the vascular wall or myocytes is high and suggests a local role for this tissue. The balance between protective and proinflammatory/profibrotic cytokines, chemokines, and adipokines released by EAT seem to be a key element in atherogenesis and could represent a future therapeutic target. EAT amount has been found to predict clinical coronary outcomes. EAT can also modulate cardiac structure and function. Its amount has been associated with atrial fibrillation, coronary artery disease, and sleep apnea syndrome. Conversely, a beiging fat profile of EAT has been identified. In this review, we describe the current state of knowledge regarding the anatomy, physiology and pathophysiological role of EAT, and the factors more globally leading to ectopic fat development. We will also highlight the most recent findings on the origin of this ectopic tissue, and its association with cardiac diseases. © 2017 American Physiological Society. Compr Physiol 7:1051-1082, 2017.

Quantitative Aortic Distensibility Measurement Using CT in Patients with Abdominal Aortic Aneurysm: Reproducibility and Clinical Relevance

Purpose. To investigate the reproducibility of aortic distensibility (D) measurement using CT and assess its clinical relevance in patients with infrarenal abdominal aortic aneurysm (AAA). Methods. 54 patients with infrarenal abdominal aortic aneurysm were studied to determine their distensibility by using 64-MDCT. Aortic cross-sectional area changes were determined at two positions of the aorta, immediately below the lowest renal artery (level 1.) and at the level of its maximal diameter (level 2.) by semiautomatic segmentation. Measurement reproducibility was assessed using intraclass correlation coefficient (ICC) and Bland-Altman analyses. Stepwise multiple regression analysis was performed to assess linear associations between aortic D and anthropometric and biochemical parameters. Results. A mean distensibility of D_{level  1.} = (1.05 ± 0.22) × 10⁻⁵  Pa⁻¹ and D_{level  2.} = (0.49 ± 0.18) × 10⁻⁵  Pa⁻¹ was found. ICC proved excellent consistency between readers over two locations: 0.92 for intraobserver and 0.89 for interobserver difference in level 1. and 0.85 and 0.79 in level 2. Multivariate analysis of all these variables showed sac distensibility to be independently related (R² = 0.68) to BMI, diastolic blood pressure, and AAA diameter. Conclusions. Aortic distensibility measurement in patients with AAA demonstrated high inter- and intraobserver agreement and may be valuable when choosing the optimal dimensions graft for AAA before endovascular aneurysm repair.

3T3-L1 cells and perivascular adipocytes are not equivalent in amine transporter expression

Rat perivascular adipose tissue (PVAT) stores, takes up, and releases norepinephrine (NE; Ayala-Lopez et al. (2014) Pharmacol Res Perspect 2, e00041). We hypothesized that 3T3-L1 adipocytes would exhibit similar behaviors and, thus, could serve as a model for PVAT adipocytes. However, basal levels of NE were not detected in 3T3-L1 adipocytes. While incubation of 3T3-L1 adipocytes with exogenous NE increased their cellular NE content, the mRNA expression of several NE transporters [e.g., norepinephrine transporter (NET)] were not detected in these cells. Similarly, we observed expression of the vesicular monoamine transporter 1 (VMAT1) in 3T3-L1 adipocytes by qRT-PCR and immunostaining, but stimulation of the cells with tyramine (100 μm) did not cause a significant release of NE. These studies support that 3T3-L1 adipocytes are not an adequate model of perivascular adipocytes for studying NE handling.

Perivascular adipose tissue as a regulator of vascular disease pathogenesis: identifying novel therapeutic targets

Adipose tissue (AT) is an active endocrine organ with the ability to dynamically secrete a wide range of adipocytokines. Importantly, its secretory profile is altered in various cardiovascular disease states. AT surrounding vessels, or perivascular AT (PVAT), is recognized in particular as an important local regulator of vascular function and dysfunction. Specifically, PVAT has the ability to sense vascular paracrine signals and respond by secreting a variety of vasoactive adipocytokines. Due to the crucial role of PVAT in regulating many aspects of vascular biology, it may constitute a novel therapeutic target for the prevention and treatment of vascular disease pathogenesis. Signalling pathways in PVAT, such as those using adiponectin, H₂ S, glucagon-like peptide 1 or pro-inflammatory cytokines, are among the potential novel pharmacological therapeutic targets of PVAT.

LINKED ARTICLES

This article is part of a themed section on Molecular Mechanisms Regulating Perivascular Adipose Tissue - Potential Pharmacological Targets? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.20/issuetoc.

Relation Between Epicardial Adipose and Aortic Valve and Mitral Annular Calcium Determined by Computed Tomography in Subjects Aged ≥65 Years

Epicardial adipose tissue (EAT) has been linked to coronary artery calcium deposits and atherosclerotic disease. Mitral annular (MAC) and aortic valve calcium (AVC) have also been associated with atherosclerosis. This study examined the possible relation between EAT thickness and valvular calcium deposits. We included 294 patients aged ≥65 years who had noncontrast computed tomography scans of the chest. Mean age was 76 ± 7 years; 47% were men. Using reconstructed images, EAT thickness was measured at various locations. MAC and AVC were quantified by Agatston technique. The sum of AVC and MAC was reported as the grand total score (GTS). Subjects were divided into 2 groups based on the value of GTS; GTS = 0, no cardiac calcification and GTS ≥1, cardiac calcification group. Epicardial fat (left and right atrioventricular grooves and superior interventricular groove) was significantly greater in the cardiac calcification group compared with the no cardiac calcification (all values, p <0.05). After adjusting for clinical variables including BMI, EAT at the superior interventricular groove remained significantly associated with total calcium. Left atrioventricular groove EAT demonstrated a trend toward an association with total calcium, but this did not reach statistical significance. In conclusion, epicardial fat is associated with calcium deposits of the mitral annulus and aortic valve.

Wild blueberry consumption attenuates local inflammation in the perivascular adipose tissue of obese Zucker rats

Perivascular adipose tissue (PVAT) has been shown to play important roles in regulating vascular tone and linking local and systemic vascular inflammation. We examined the impact of PVAT on phenylephrine-mediated vasoconstriction in the aorta of obese Zucker rats (OZR) and their lean littermates (LZR) by comparing aortic rings with or without PVAT. Subsequently we placed OZR and LZR on a control (C) or an 8% wild blueberry (WB) diet and evaluated the effect of WB consumption on such response. PVAT-released adipokine concentrations were also measured as a function of WB diet. Maximal constrictor force (Fmax) in aortic rings without PVAT was significantly lower in OZR-C compared with LZR-C (0.41 ± 0.05 and 0.71 ± 0.06 g, respectively). Following WB diet, Fmax significantly increased in OZR (0.54 ± 0.06 g). In aortas with intact PVAT, Fmax was significantly lower in all groups (0.31 ± 0.06 OZR-C, 0.30 ± 0.05 OZR-WB, 0.29 ± 0.03 LZR-C, and 0.30 ± 0.04 g LZR-WB), but no difference was observed between treatments. PVAT concentrations of monocyte chemoactractant protein 1 (MCP-1), tumor necrosis factor alpha, and adiponectin were significantly higher in OZR compared with LZR (+102%, +108%, and +45%, respectively). Following WB diet, PVAT concentrations of interleukin-8 were significantly lower in both OZR (-37%) and LZR (-30%), while adiponectin concentrations significantly increased in both OZR (+11%) and LZR (+16%). MCP-1 concentrations significantly decreased (-31%) in the PVAT of OZR with the WB diet. WB consumption appears to attenuate local inflammation in PVAT, which may impact systemic vascular inflammation and endothelial function.

Localizing factors in atherosclerosis

Atherosclerotic vascular disease is the leading cause of death worldwide. Although the entire vascular bed is constantly exposed to the same risk factors, atheromatous lesions present a distinct intra-individual pattern of localization and progression, being consistently more frequent in specific segments of the arterial vascular bed. This peculiar distribution may be related to selective sensitivity of such locations to the influence of risk factors or to histopathological and flow differences, and has relevant clinical implications, as the prognosis of the disease varies according to localization. We here review the theories that have been formulated to explain such preferential locations, as its understanding can be useful to pursue diagnostic screening strategies and focused preventive measures.

Perivascular adipose tissue: An unique fat compartment relevant for the cardiometabolic syndrome

Type 2 diabetes and its major risk factor, obesity, are an increasing worldwide health problem. The exact mechanisms that link obesity with insulin resistance, type 2 diabetes, hypertension, cardiovascular complications and renal diseases, are still not clarified sufficiently. Adipose tissue in general is an active endocrine and paracrine organ that may influence the development of these disorders. Excessive body fat in general obesity may also cause quantitative and functional alterations of specific adipose tissue compartments. Beside visceral and subcutaneous fat depots which exert systemic effects by the release of adipokines, cytokines and hormones, there are also locally acting fat depots such as peri- and epicardial fat, perivascular fat, and renal sinus fat. Perivascular adipose tissue is in close contact with the adventitia of large, medium and small diameter arteries, possesses unique features differing from other fat depots and may act also independently of general obesity. An increasing number of studies are dealing with the "good" or "bad" characteristics and functions of normally sized and dramatically increased perivascular fat mass in lean or heavily obese individuals. This review describes the origin of perivascular adipose tissue, its different locations, the dual role of a physiological and unphysiological fat mass and its impact on diabetes, cardiovascular and renal diseases. Clinical studies, new imaging methods, as well as basic research in cell culture experiments in the last decade helped to elucidate the various aspects of the unique fat compartment.

The association among peri-aortic root adipose tissue, metabolic derangements and burden of atherosclerosis in asymptomatic population

AIM

To describe the relationship between a novel measurement of peri-arotic root fat and ultrasound measures of carotid artery remodeling.

MATERIALS AND METHODS

We studied 1492 consecutive subjects (mean age: 51.04 ± 8.97 years, 27% females) who underwent an annual cardiovascular risk survey in Taiwan. Peri-aortic root fat (PARF) was assessed by cardiac CT using three-dimensional (3D) volume assessment. Carotid artery morphology and remodeling were assessed by ultrasound. We explored the relationships between PARF volumes, cardiometabolic risk profiles and carotid morphology and remodeling.

RESULTS

Mean PARF volume in current study was 20.8 ± 10.6 ml. PARF was positively correlated with measures of general adiposity, systemic inflammation, and several traditional cardiometabolic risk profiles (all p < 0.001) and successfully predicted metabolic syndrome (MetS) (AUROC: 0.75, 95%, confidence interval: 0.72-0.77). Higher PARF was independently associated with increased carotid artery intima-media thickness (IMT) (β-coef.: 0.08) and diameter (β-coef.: 0.08, both p < 0.05) after accounting for age, sex, BMI and other cardiovascular risk factors. The addition of PARF beyond metabolic syndrome components significantly provided incremental prediction value for abnormal IMT (ΔAUROC: 0.053, p = 0.0021).

CONCLUSION

Peri-aortic root fat is associated with carotid IMT, even after adjustment for cardiometabolic risks, age and coronary atherosclerosis. Further research studies are warranted to identify the mediators of downstream pathophysiologic effects on carotid arteries by PARF and understand the mechanisms related to this correlation.

Perivascular adipose tissue: role in the pathogenesis of obesity, type 2 diabetes mellitus and cardiovascular pathology

Perivascular adipose tissue is a part of blood vessel wall, regulating endovascular homeostasis, endothelial and smooth muscle cells functioning. Under physiological conditions, perivascular tissue provides beneficial anticontractile effect, though undergoes structural and functional changes in obesity, atherosclerosis and diabetes mellitus type2.Collected data suggest the possible key role of perivascular adipose tissue in the pathogenesis of these diseases. Perivascular tissue has been determined as an independent cardiovascular risk factor, regardless of visceral obesity. General mechanisms include a local low-grade inflammation, oxidative stress, tissue renin-angiotensin-aldosterone system activation, paracrine and metabolic alterations. Properties of perivascular adipose tissue depend on the certain type of adipocytes it contains. Brown adipocytes are well known for their metabolic preferences, however it has been shown recently that brown perivascular tissue can contribute to dyslipidemia under some conditions.  The aim of this review is to discuss the current literature understanding of perivascular adipose tissue specifics, changes in its activity, secretory and genetic profilein a course of the most common non-infectious diseases development, as well as molecular mechanisms of its functioning. We also discuss perspectives of target interventions using metabolic pathways and genes of perivascular tissue, for the effective prevention of obesity, diabetes mellitus type2 and cardiovascular diseases.

Thoracic fat volume is independently associated with coronary vasomotion

PURPOSE

Thoracic fat has been associated with an increased risk of coronary artery disease (CAD). As endothelium-dependent vasoreactivity is a surrogate of cardiovascular events and is impaired early in atherosclerosis, we aimed at assessing the possible relationship between thoracic fat volume (TFV) and endothelium-dependent coronary vasomotion.

METHODS

Fifty healthy volunteers without known CAD or major cardiovascular risk factors (CRFs) prospectively underwent a (82)Rb cardiac PET/CT to quantify myocardial blood flow (MBF) at rest, and MBF response to cold pressor testing (CPT-MBF) and adenosine (i.e., stress-MBF). TFV was measured by a 2D volumetric CT method and common laboratory blood tests (glucose and insulin levels, HOMA-IR, cholesterol, triglyceride, hsCRP) were performed. Relationships between CPT-MBF, TFV and other CRFs were assessed using non-parametric Spearman rank correlation testing and multivariate linear regression analysis.

RESULTS

All of the 50 participants (58 ± 10y) had normal stress-MBF (2.7 ± 0.6 mL/min/g; 95 % CI: 2.6-2.9) and myocardial flow reserve (2.8 ± 0.8; 95 % CI: 2.6-3.0) excluding underlying CAD. Univariate analysis revealed a significant inverse relation between absolute CPT-MBF and sex (ρ = -0.47, p = 0.0006), triglyceride (ρ = -0.32, p = 0.024) and insulin levels (ρ = -0.43, p = 0.0024), HOMA-IR (ρ = -0.39, p = 0.007), BMI (ρ = -0.51, p = 0.0002) and TFV (ρ = -0.52, p = 0.0001). MBF response to adenosine was also correlated with TFV (ρ = -0.32, p = 0.026). On multivariate analysis, TFV emerged as the only significant predictor of MBF response to CPT (p = 0.014).

CONCLUSIONS

TFV is significantly correlated with endothelium-dependent and -independent coronary vasomotion. High TF burden might negatively influence MBF response to CPT and to adenosine stress, even in persons without CAD, suggesting a link between thoracic fat and future cardiovascular events.

The relationship of periaortic fat thickness and cardiovascular risk factors in children with Turner syndrome

Children with Turner syndrome (TS) have a broad range of later health problems, including an increased risk of cardiovascular morbidity and mortality. The aim of this study was to evaluate the relationship between periaortic fat thickness (PAFT) and metabolic and cardiovascular profiles in children with TS. Twenty-nine TS and 29 healthy children and adolescents were enrolled in the study. Anthropometric measurements, pubertal staging, and blood pressure measurements were performed. Fasting serum glucose, insulin, and lipid profile were measured. Periaortic fat thickness was measured using an echocardiography method, which has not previously been applied in children with TS. No difference was found between TS and control subject (CS) in age, weight, waist/hip ratio, HDL cholesterol and LDL cholesterol levels. However, in TS subjects, total cholesterol (p = 0.045) was greater than that in controls. It was determined that 13.7 % (N: 4) of TS subjects had dyslipidemia. Mean fasting glucose, fasting insulin, QUICK-I, HOMA, and FGIR index were similar in TS and in CS, whereas 17.2 % (N: 5) of TS subjects had insulin resistance (IR) and 13.7 % (N: 4) had impaired glucose tolerance. Six subjects (20.6 %) were diagnosed as hypertensive. Periaortic fat thickness was significantly higher in the TS group (p < 0.001) (0.1694 ± 0.025 mm in the TS group and 0.1416 ± 0.014 mm in the CS group) In children with TS, PAFT was positively correlated with fasting insulin, body mass index, and diastolic blood pressure. Our results provide additional evidence for the presence of subclinical cardiovascular disease in TS. In addition to existing methods, we recommend the measurement of periaortic fat thickness in children with TS to reveal the presence of early atherosclerosis.

Vasa vasorum in atherosclerosis and clinical significance

Atherosclerosis is a chronic inflammatory disease that leads to several acute cardiovascular complications with poor prognosis. For decades, the role of the adventitial vasa vasorum (VV) in the initiation and progression of atherosclerosis has received broad attention. The presence of VV neovascularization precedes the apparent symptoms of clinical atherosclerosis. VV also mediates inflammatory cell infiltration, intimal thickening, intraplaque hemorrhage, and subsequent atherothrombosis that results in stroke or myocardial infarction. Intraplaque neovessels originating from VV can be immature and hence susceptible to leakage, and are thus regarded as the leading cause of intraplaque hemorrhage. Evidence supports VV as a new surrogate target of atherosclerosis evaluation and treatment. This review provides an overview into the relationship between VV and atherosclerosis, including the anatomy and function of VV, the stimuli of VV neovascularization, and the available underlying mechanisms that lead to poor prognosis. We also summarize translational researches on VV imaging modalities and potential therapies that target VV neovascularization or its stimuli.

Co-cultivation of human aortic smooth muscle cells with epicardial adipocytes affects their proliferation rate

The abnormal proliferation of vascular smooth muscle cells (VSMC) is thought to play a role in the pathogenesis of atherosclerosis. Adipocytes produce several bioactive paracrine substances that can affect the growth and migration of VSMCs. Our study focuses on the direct effect of the bioactive substances in conditioned media (CM) that was obtained by incubation with primary adipocyte-derived cell lines, including cell lines derived from both preadipocytes and from more mature cells, on the proliferation rate of human aortic smooth muscle cells (HAoSMCs). We used a Luminex assay to measure the adipokine content of the CM and showed that there was a higher concentration of monocyte chemoattractant protein-1 in renal preadipocyte-CM compared with the HAoSMC control (p<0.5). The addition of both renal preadipocyte- and epicardial adipocyte- CM resulted in the elevated production of vascular endothelial growth factor compared with the control HASoSMC CM (p<0.001). The adiponectin content in renal adipocyte-CM was increased compared to all the remaining adipocyte-CM (p<0.01). Moreover, the results showed a higher proliferation rate of HAoSMCs after co-culture with epicardial adipocyte-CM compared to the HAoSMC control (p<0.05). These results suggest that bioactive substances produced by adipocytes have a stimulatory effect on the proliferation of VSMCs.

Thoracic periaortic adipose tissue in relation to cardiovascular risk in type 2 diabetes mellitus

OBJECTIVE

To evaluate thoracic periaortic adipose tissue (TAT) burden in patients with type 2 diabetes mellitus (DM) in comparison with controls and in relation to cardiovascular risk factors.

METHODS

A total of 93 patients with type 2 DM (mean (standard deviation; SD) age: 56.7 (11.2) years, 71.0 % were men) and 85 nondiabetic control subjects (mean (SD) age: 54.6 (10.9) years, 58.8 % were men) who were admitted to Mevlana University hospital between January 2011 and June 2013 and underwent multidetector computed tomography for any reason were included in this retrospective cohort study. Patient and control groups were compared in terms of demographic characteristics, anthropometrics, and laboratory findings. TAT volume was evaluated in both groups, while correlates of TAT were determined via linear regression analysis among patients.

RESULTS

In patients with type 2 DM, TAT volume (40.1 (23.9) versus 16.9 (7.7) cm(3), p < 0.001), fasting blood glucose (p < 0.001), total cholesterol (p < 0.001), triglyceride (p = 0.017), and low-density lipoprotein (LDL) cholesterol (p = 0.034) levels were significantly higher compared with the control group. Strong positive correlation of TAT was noted with body mass index (r = 0.339, p = 0.001) and serum levels for fasting blood glucose (r = 0.343, p < 0.001), hemoglobin A1c (HbA1c; r = 0.615, p < 0.001), total cholesterol (r = 0.269, p = 0.009), and LDL cholesterol (r = 0.258, p = 0.013). In stepwise regression analysis, Hba1c emerged as a significant predictor of TAT (b = 0.610, p < 0.001), contributing to 19 % of its variability.

CONCLUSION

In conclusion, our findings indicate significantly higher values for TAT in diabetics than controls, being associated positively with body weight, poor glycemic control, and dyslipidemia and strongly predicted by HbA1c levels in diabetic patients, while not differing with respect to gender, smoking status, and concomitant hypertension.

Short-term response of metabolic hormones to coronary artery bypass surgery

PURPOSE

To explore the response pattern of plasma adipokine and ghrelin levels to coronary artery bypass graft (CABG) surgery in patients with (on-pump) and without (off-pump) cardiopulmonary bypass (CPB).

MATERIAL/METHODS

Sixteen consecutive patients (age: 62 ± 10 years, male: 10) with obstructive coronary artery disease (CAD) who underwent elective CABG surgery with CPB and intraoperative GIK infusion were selected for on-pump group and 19 CAD patients (age: 63 ± 10 years, male: 16) were included in the off-pump group. Blood samples were taken before, during and after surgery. Intraoperative samples were withdrawn simultaneously for peripheral vein and sinus coronarius (SC). Plasma adipokine concentrations were measured by ELISA, those of ghrelin by RIA kits.

RESULTS

In response to surgical intervention there was an early, transient fall in plasma levels of adiponectin (p<0.0001) and resistin (p=0.002) followed by an increase to approach their initial values. Plasma ghrelin also increased (p=0.045), this increase, however, was confined to the period of GIK supported CPB. Plasma insulin (p=0.003) and resistin (p=0.009) was significantly higher in the peripheral vein than in SC. The perioperative hormone profile of patients without CPB (off-pump) proved to be comparable to that of on-pump patients in spite of the insulin administration and greater oxidative and inflammatory stress.

CONCLUSIONS

Adipose tissue-derived factors appear to mediate the metabolic and vascular changes that occur in patients with CABG surgery. Epicardial adipose tissue is unlikely to have major contribution to the development of CAD as adipokines are not elevated in SC independent of the mode of intervention.