Carotid Artery Perivascular Adipose Tissue Density and Response to Intravenous Tissue Plasminogen Activator in Acute Ischemic Stroke

The importance of Carotid Artery Perivascular Adipose Tissue Density (CAPATd), a parameter that can be readily evaluated on emergency computed tomographic angiography (CTA), in acute stroke has not been adequately clarified. We created exploratory logistic regression models to detect the interaction between the effect of CAPATd and intravenous (IV) tissue plasminogen activator (tPA) in 174 patients (mean age 71 ± 14 years, 94 women) with acute ischemic stroke treated with IV-tPA alone. The CAPATd-average mean (-60.6 ± 18.7 vs -89.8 ± 25.3 Hounsfield units (HU), P = .002) and CAPATd-maximum (14.8 ± 68.9 vs -20.5 ± 39.8 HU, P = .020) values were higher on the ipsilateral side of carotid artery stenosis >60%. CAPATd-maximum ipsilateral emerged as an independent predictor for both modified Rankin's Score 0-2 (52%) [exp(β) = .984] and mRS 0-1 outcome (32%) [exp(β) = .828] in addition to admission National Institutes of Health Stroke Scale, age and carotid plaque burden. CAPATd-maximum ipsilateral was acceptably accurate (Area under the Receiver operating characteristic Curve was .607, P = .0109 for mRS 0-2 and .613, P = .0102 for mRS 0-1). Ipsilateral CAPATd ≥ -25 HU predicted both mRS >3 and mRS >2 with usable sensitivity (59.8% and 66.07%) and specificity (63.6% and 59.68%). In conclusion, higher maximum CAPATd measured on emergency CTA indicates poorer functional prognosis in acute stroke patients treated with IV-tPA.

A cell atlas of thoracic aortic perivascular adipose tissue: a focus on mechanotransducers

Perivascular adipose tissue (PVAT) is increasingly recognized for its function in mechanotransduction. However, major gaps remain in our understanding of the cells present in PVAT, as well as how different cells contribute to mechanotransduction. We hypothesized that snRNA-seq would reveal the expression of mechanotransducers, and test one (PIEZO1) to illustrate the expression and functional agreement between single-nuclei RNA sequencing (snRNA-seq) and physiological measurements. To contrast two brown tissues, subscapular brown adipose tissue (BAT) was also examined. We used snRNA-seq of the thoracic aorta PVAT (taPVAT) and BAT from male Dahl salt-sensitive (Dahl SS) rats to investigate cell-specific expression mechanotransducers. Localization and function of the mechanostransducer PIEZO1 were further examined using immunohistochemistry (IHC) and RNAscope, as well as pharmacological antagonism. Approximately 30,000 nuclei from taPVAT and BAT each were characterized by snRNA-seq, identifying eight major cell types expected and one unexpected (nuclei with oligodendrocyte marker genes). Cell-specific differential gene expression analysis between taPVAT and BAT identified up to 511 genes (adipocytes) with many (≥20%) being unique to individual cell types. Piezo1 was the most highly, widely expressed mechanotransducer. The presence of PIEZO1 in the PVAT but not the adventitia was confirmed by RNAscope and IHC in male and female rats. Importantly, antagonism of PIEZO1 by GsMTX4 impaired the PVAT's ability to hold tension. Collectively, the cell compositions of taPVAT and BAT are highly similar, and PIEZO1 is likely a mechanotransducer in taPVAT.NEW & NOTEWORTHY This study describes the atlas of cells in the thoracic aorta perivascular adipose tissue (taPVAT) of the Dahl-SS rat, an important hypertension model. We show that mechanotransducers are widely expressed in these cells. Moreover, PIEZO1 expression is shown to be restricted to the taPVAT and is functionally implicated in stress relaxation. These data will serve as the foundation for future studies investigating the role of taPVAT in this model of hypertensive disease.

β-Adrenergic Stimulation-Induced PVAT Dysfunction in Male Sex: A Role for 11β-Hydroxysteroid Dehydrogenase-1

Long-term β-adrenoceptor (β-AR) stimulation is a pathological mechanism associated with cardiovascular diseases resulting in endothelial and perivascular adipose tissue (PVAT) dysfunction. In this study, we aimed to identify whether β-adrenergic signaling has a direct effect on PVAT. Thoracic aorta PVAT was obtained from male Wistar rats and cultured ex vivo with the β-AR agonist isoproterenol (Iso; 1 µM) or vehicle for 24 hours. Conditioned culture medium (CCM) from Iso-treated PVAT induced a marked increase in aorta contractile response, induced oxidative stress, and reduced nitric oxide production in PVAT compared to vehicle. In addition, Iso-treated PVAT and PVAT-derived differentiated adipocytes exhibited higher corticosterone release and protein expression of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), an enzyme responsible for de novo synthesis of corticosterone. Macrophages exposed to Iso also exhibited increased corticosterone release in response to β-AR stimulation. Incubation of Iso-treated PVAT and PVAT-derived differentiated adipocytes with β3-AR antagonist restored aorta contractile function modulated by Iso-CCM and normalized 11β-HSD1 protein expression. These results show that β3-AR signaling leads to upregulation of 11β-HSD1 in PVAT, thus increasing corticosterone release and contributing to impair the anticontractile function of this tissue.

Pericarotid Adipose Tissue is Associated with Circulatory Markers of Inflammation and Carotid Atherosclerosis

Perivascular adipose tissue plays roles in vascular inflammation and atherosclerosis. The present study aimed to evaluate the association between pericarotid fat density (PFD) and circulatory inflammatory indicators, internal carotid artery (ICA) stenosis, and vulnerable carotid plaques. We retrospectively screened 498 consecutive patients who underwent both computed tomography angiography of the neck between January 2017 and December 2020. The PFD, ICA stenosis, and vulnerable carotid plaques were analyzed using established approaches. Laboratory data including C-reactive protein (CRP) levels, lymphocyte-to-monocyte ratio (LMR), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune inflammation index (SII) were recorded. PFD was positively correlated with CRP, NLR, PLR, and SII, and negatively correlated with LMR. A higher PFD was independently associated with extracranial ICA stenosis (1.179 [1.003-1.387], P = .040) and vulnerable carotid plaques (1.046 [1.021-1.072], P = .001) after adjusting for systemic inflammatory indicators. These findings suggested higher PFD is independently associated with circulating inflammatory indicators, extracranial ICA stenosis, and vulnerable carotid plaque.

Initial experience with radiomics of carotid perivascular adipose tissue in identifying symptomatic plaque

Background

Carotid atherosclerotic ischemic stroke threatens human health and life. The aim of this study is to establish a radiomics model of perivascular adipose tissue (PVAT) around carotid plaque for evaluation of the association between Peri-carotid Adipose Tissue structural changes with stroke and transient ischemic attack.

Methods

A total of 203 patients underwent head and neck computed tomography angiography examination in our hospital. All patients were divided into a symptomatic group (71 cases) and an asymptomatic group (132 cases) according to whether they had acute/subacute stroke or transient ischemic attack. The radiomic signature (RS) of carotid plaque PVAT was extracted, and the minimum redundancy maximum correlation, recursive feature elimination, and linear discriminant analysis algorithms were used for feature screening and dimensionality reduction.

Results

It was found that the RS model achieved the best diagnostic performance in the Bagging Decision Tree algorithm, and the training set (AUC, 0.837; 95%CI: 0.775, 0.899), testing set (AUC, 0.834; 95%CI: 0.685, 0.982). Compared with the traditional feature model, the RS model significantly improved the diagnostic efficacy for identifying symptomatic plaques in the testing set (AUC: 0.834 vs. 0.593; Z = 2.114, p = 0.0345).

Conclusion

The RS model of PVAT of carotid plaque can be used as an objective indicator to evaluate the risk of plaque and provide a basis for risk stratification of carotid atherosclerotic disease.

Peri-Carotid Adipose Tissue and Atherosclerosis at Carotid Bifurcation

Vulnerable carotid plaques are responsible for 20% of the ischemic strokes. The identification of these asymptomatic carotid plaques that will become symptomatic is essential but remains unclear. Our main goal was to investigate whether the amount of the peri-carotid adipose tissue, estimated by the extra-media thickness (EMT), is associated with the atherosclerotic characteristics at the carotid bifurcation in patients with PAD. An observational, prospective, single-center, longitudinal study was conducted. Overall, 177 patients were subjected to carotid Doppler ultrasound at the study admission. The following data were collected: EMT, intima-media thickness (IMT), the presence of carotid plaques, the area of the highest plaque, the presence of "acute culprit" carotid stenosis, and the grade of internal carotid stenosis. "Acute culprit" carotid stenosis was defined as a significant atherosclerotic plaque that leads to a neurologic event within 15 days. From each carotid bifurcation, a right and a left EMT were determined. We analyzed both the mean EMTs (calculated as the mean between the right and the left EMT) and the EMT ipsilateral to the carotid bifurcation. The presence of carotid plaques was associated with a higher mean EMT [Median = 1.14; IQR = 0.66 versus Median = 0.97; IQR = 0.40; p = 0.001]. A positive correlation was found between the mean EMT and IMT (right: ρ = 0.20; p = 0.010; left: ρ = 0.21; p = 0.007) and between the mean EMT and the area of the largest carotid plaque (right: ρ = 0.17; p = 0.036; left: ρ = 0.22; p = 0.004). Left carotid stenosis ≥ 70% was associated with higher ipsilateral EMT [Median = 1.56; IQR = 0.70 versus Median = 0.94; IQR = 0.42; p = 0.009]. Patients with "acute culprit" carotid stenosis had a higher ipsilateral EMT [left ipsilateral EMT: Median = 1.46; IQR = 0.63; "non-acute": Median = 0.94; IQR = 0.43; p = 0.009; right ipsilateral EMT: Median = 2.25; IQR = 0.62; "non-acute": Median = 1.00; IQR = 0.51; p = 0.015]. This difference was not found in the contra-lateral EMT. Six months after the neurologic event, EMT ipsilateral to an "acute culprit" carotid stenosis decreased (p = 0.036). The amount of peri-carotid adipose tissue, estimated with EMT, was associated with atherosclerosis at the carotid arteries. The mean EMT was associated with the features of chronic atherosclerosis lesions: the presence of carotid plaques, IMT, and the area of the highest plaque. Ipsilateral EMT was linked with "acute culprit" atherosclerotic plaque.

Relationship Between Perivascular Adipose Tissue and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis

We conducted a systematic review and meta-analysis aimed at estimating the association between perivascular adipose tissue (PVAT) and some of the cardiovascular risk factors. A systematic search was conducted from January 1980 up to and including 2022 to identify studies that examined the relationship between PVAT and cardiovascular risk factors as obesity and its indices, hypertension, lipids, and glucose intolerance/diabetes. The Medline and Embase databases were searched using the PubMed and Scopus. Data were extracted from 23 studies that fit the criteria. To conduct meta-analysis, we used an approximation of equating the method of correlating assessment because different authors used either Pearson or Spearman correlation. Interrelations of PVAT and body mass index were analyzed in eight studies. Most studies revealed reliable direct correlation; the results of the meta-analysis also showed a significant (P = 0.37, P < 0.01, n = 12,346) correlation. PVAT and waist circumference were analyzed in six studies. Meta-analysis on the selected sample (n = 10,947) showed a significant (r = 0.45, P < 0.01) correlation. Relationship between PVAT and hypertension was revealed in three studies. Direct correlations were found in all studies. Meta-analysis showed the reliability of the correlation dependence (r = 0.21, P < 0.01, n = 3996). PVAT and blood glucose was evaluated in three studies (n = 3689). In each study a reliable (P < 0.05) direct correlation was obtained. Meta-analysis showed a significant correlation of weak strength (r = 0.24, P < 0.01). We demonstrated significant positive correlations of PVAT with the levels of total cholesterol (r = 0.05, P < 0.01), low-density lipoprotein cholesterol (r = 0.13, P < 0.01), and triglycerides (r = 0.29, P < 0.01), and a negative relationship with high-density lipoprotein cholesterol (r = -0.18, P < 0.01) in this meta-analysis. Despite some limitations, the findings of this systematic review and meta-analysis confirmed that PVAT significantly correlates with studied cardiovascular risk factors. Because PVAT presents a great interest in terms of cardiovascular remodeling and cardiovascular disease, its assessment in patients with and without cardiovascular pathology needs further research.

Protective role of perivascular adipose tissue in the cardiovascular system

This review provides an overview of the key role played by perivascular adipose tissue (PVAT) in the protection of cardiovascular health. PVAT is a specific type of adipose tissue that wraps around blood vessels and has recently emerged as a critical factor for maintenance of vascular health. Through a profound exploration of existing research, this review sheds light on the intricate structural composition and cellular origins of PVAT, with a particular emphasis on combining its regulatory functions for vascular tone, inflammation, oxidative stress, and endothelial function. The review then delves into the intricate mechanisms by which PVAT exerts its protective effects, including the secretion of diverse adipokines and manipulation of the renin-angiotensin complex. The review further examines the alterations in PVAT function and phenotype observed in several cardiovascular diseases, including atherosclerosis, hypertension, and heart failure. Recognizing the complex interactions of PVAT with the cardiovascular system is critical for pursuing breakthrough therapeutic strategies that can target cardiovascular disease. Therefore, this review aims to augment present understanding of the protective role of PVAT in cardiovascular health, with a special emphasis on elucidating potential mechanisms and paving the way for future research directions in this evolving field.

Angiotensin II type 2 receptor as a novel activator of brown adipose tissue in obesity

The angiotensin II type 2 receptor (AT2R) exerts vasorelaxant, anti-inflammatory, and antioxidant properties. In obesity, its activation counterbalances the adverse cardiovascular effects of angiotensin II mediated by the AT1R. Preliminary results indicate that it also promotes brown adipocyte differentiation in vitro. Our hypothesis is that AT2R activation could increase BAT mass and activity in obesity. Five-week-old male C57BL/6J mice were fed a standard or a high-fat (HF) diet for 6 weeks. Half of the animals were treated with compound 21 (C21), a selective AT2R agonist, (1 mg/kg/day) in the drinking water. Electron transport chain (ETC), oxidative phosphorylation, and UCP1 proteins were measured in the interscapular BAT (iBAT) and thoracic perivascular adipose tissue (tPVAT) as well as inflammatory and oxidative parameters. Differentiation and oxygen consumption rate (OCR) in the presence of C21 was tested in brown preadipocytes. In vitro, C21-differentiated brown adipocytes showed an AT2R-dependent increase of differentiation markers (Ucp1, Cidea, Pparg) and increased basal and H+ leak-linked OCR. In vivo, HF-C21 mice showed increased iBAT mass compared to HF animals. Both their iBAT and tPVAT showed higher protein levels of the ETC protein complexes and UCP1, together with a reduction of inflammatory and oxidative markers. The activation of the AT2R increases BAT mass, mitochondrial activity, and reduces markers of tissue inflammation and oxidative stress in obesity. Therefore, insulin reduction and better vascular responses are achieved. Thus, the activation of the protective arm of the renin-angiotensin system arises as a promising tool in the treatment of obesity.

Vasodilator Responses of Perivascular Adipose Tissue-Derived Hydrogen Sulfide Stimulated with L-Cysteine in Pregnancy Hypertension-Induced Endothelial Dysfunction in Rats

Endothelium-derived nitric oxide (NO)-induced vasodilation is impaired in pregnancy hypertension. However, the role of perivascular adipose tissue (PVAT)-derived hydrogen sulfide (H2S), as an alternative for counteracting vascular dysfunction, is incompletely clear in hypertensive disorders of pregnancy. Therefore, PVAT-derived H2S-induced vasodilation was investigated in pregnancy hypertension-induced endothelial dysfunction. Non-pregnant (Non-Preg) and pregnant (Preg) rats were submitted (or not) to the deoxycorticosterone (DOCA)-salt protocol and assigned as follows (n = 10/group): Non-Preg, Non-Preg+DOCA, Preg, and Preg+DOCA groups. Systolic blood pressure (SBP), angiogenesis-related factors, determinant levels of H2S (PbS), NO (NOx), and oxidative stress (MDA) were assessed. Vascular changes were recorded in thoracic aortas with PVAT and endothelium (intact and removed layers). Vasorelaxation responses to the substrate (L-cysteine) for the H2S-producing enzyme cystathionine-γ-lyase (CSE) were examined in the absence and presence of CSE-inhibitor DL-propargylglycine (PAG) in thoracic aorta rings pre-incubated with cofactor for CSE (pyridoxal-5 phosphate: PLP) and pre-contracted with phenylephrine. Hypertension was only found in the Preg+DOCA group. Preg+DOCA rats showed angiogenic imbalances and increased levels of MDA. PbS, but not NOx, showed increased levels in the Preg+DOCA group. Pre-incubation with PLP and L-cysteine elevated determinants of H2S in PVAT and placentas of Preg-DOCA rats, whereas no changes were found in the aortas without PVAT. Aortas of Preg-DOCA rats showed that PVAT-derived H2S-dependent vasodilation was greater compared to endothelium-derived H2S, whereas PAG blocked these responses. PVAT-derived H2S endogenously stimulated with the amino acid L-cysteine may be an alternative to induce vasorelaxation in endothelial dysfunction related to pregnancy hypertension.

Notch Signaling Regulates Mouse Perivascular Adipose Tissue Function via Mitochondrial Pathways

Perivascular adipose tissue (PVAT) regulates vascular function by secreting vasoactive substances. In mice, Notch signaling is activated in the PVAT during diet-induced obesity, and leads to the loss of the thermogenic phenotype and adipocyte whitening due to increased lipid accumulation. We used the Adiponectin-Cre (Adipoq-Cre) strain to activate a ligand-independent Notch1 intracellular domain transgene (N1ICD) to drive constitutive Notch signaling in the adipose tissues (N1ICD;Adipoq-Cre). We previously found that constitutive activation of Notch1 signaling in the PVAT phenocopied the effects of diet-induced obesity. To understand the downstream pathways activated by Notch signaling, we performed a proteomic analysis of the PVAT from control versus N1ICD;Adipoq-Cre mice. This comparison identified prominent changes in the protein signatures related to metabolism, adipocyte homeostasis, mitochondrial function, and ferroptosis. PVAT-derived stromal vascular fraction cells were derived from our mouse strains to study the cellular and molecular phenotypes during adipogenic induction. We found that cells with activated Notch signaling displayed decreased mitochondrial respiration despite similar levels of adipogenesis and mitochondrial number. We observed variable regulation of the proteins related to mitochondrial dynamics and ferroptosis, including PHB3, PINK1, pDRP1, and the phospholipid hydroperoxidase GPX4. Mitochondria regulate some forms of ferroptosis, which is a regulated process of cell death driven by lipid peroxidation. Accordingly, we found that Notch activation promoted lipid peroxidation and ferroptosis in PVAT-derived adipocytes. Because the PVAT phenotype is a regulator of vascular reactivity, we tested the effect of Notch activation in PVAT on vasoreactivity using wire myography. The aortae from the N1ICD;Adipoq-Cre mice had increased vasocontraction and decreased vasorelaxation in a PVAT-dependent and age-dependent manner. Our data provide support for the novel concept that increased Notch signaling in the adipose tissue leads to PVAT whitening, impaired mitochondrial function, increased ferroptosis, and loss of a protective vasodilatory signal. Our study advances our understanding of how Notch signaling in adipocytes affects mitochondrial dynamics, which impacts vascular physiology.

Association Between Aneurysm Wall Inflammation Detected by Imaging Perivascular Fat and Secondary Intervention Risk for Abdominal Aortic Aneurysm Patients After Endovascular Repair

OBJECTIVE

To investigate the association between the imaging biomarker (volumetric perivascular characterization index [VPCI]) which indicates the aortic wall inflammation by mapping the spatial changes of perivascular fat attenuation on computed tomography angiography (CTA) and the reintervention risk for abdominal aortic aneurysm (AAA) patients after endovascular aortic repair (EVAR).

METHODS

This case-control study included AAA patients undergoing EVAR from a single center (n=260). Cases were AAA patients undergoing reintervention after EVAR and a 1:1 frequency-matched control group of AAA patients post-EVAR with a shrunken or ≥3-year stable sac and free of reintervention signs during the follow-up. The predictive variable (VPCI trajectory) was converted to binary variables according to the changing trend of VPCI with follow-up time. As a quasi-complete separation data pattern, least absolute shrinkage and selection operator (lasso) regression was used to screen and prove the VPCI trajectory as the best predictor, and the performance was evaluated by calculating the accuracy, sensitivity, and specificity.

RESULTS

Between 2010 and 2021, 15 AAA patients after EVAR with type I/III endoleak, aneurysm rupture, or impending rupture were included. Compared with the 1:1 frequency-matched controls with a shrunken or ≥3-year stable sac and free of reintervention signs during the follow-up, VPCI trajectories of the case group were all upward trends, whereas the controls showed 86.7% downward trends (p<0.001). The best predictive model of lasso regressions included 4 variables, and VPCI trajectory was the most outstanding, followed by the proximal landing zone, the distal landing zone, and the infrarenal β angle. The accuracy, sensitivity, and specificity of predicting the risk of reintervention were as follows, respectively: 93.3%, 100%, and 86.7%.

CONCLUSIONS

The wall inflammation detected by imaging perivascular adipose tissue based on the CTAs was strongly associated with the reintervention risk for AAA patients after EVAR, which might hold major promise as a new imaging biomarker for the mechanism and treatment study of human AAAs before and after EVAR.

CLINICAL IMPACT

The study introduces a novel imaging biomarker which indicates the aortic wall inflammation by mapping spatial changes of perivascular fat attenuation on CTA. This biomarker demonstrates a strong association with the reintervention risk in AAA patients after EVAR. Incorporation of VPCI into clinical practice has the potential to enhance the traditional surveillance methods (CT/CTAs) by providing clinicians with a non-invasive method to assess aortic wall inflammation and predict the risk of reintervention. Additionally, this study might offer a valuable tool for mechanism and treatment research in humans with AAAs both pre- and post-EVAR, ultimately improving patient outcomes and refining therapeutic strategies.

Nicotine Impairs the Anti-Contractile Function of Perivascular Adipose Tissue by Inhibiting the PPARγ-Adiponectin-AdipoR1 Axis

Nicotine is an addictive compound found in cigarette smoke that leads to vascular dysfunction and cardiovascular diseases. Perivascular adipose tissue (PVAT) exerts an anti-contractile effect on the underlying vasculature through the production of adipokines, such as adiponectin, which acts on adiponectin receptors 1 (adipoR1) to cause vasorelaxation. Peroxisome proliferator-activated receptor gamma (PPARγ) is a transcription factor that regulates adiponectin gene expression and PVAT development. This study aimed to determine the effect of nicotine on the anti-contractile function of PVAT via the PPARγ-adiponectin-adipoR1 axis. Male Sprague Dawley rats were divided into a control group (given normal saline), a nicotine group (given 0.8 mg/kg of nicotine), and a nicotine + PPARγ agonist group (given nicotine and 5 mg/kg of telmisartan). Thoracic aorta PVAT was harvested after 21 days of treatment. The results showed that nicotine reduced the anti-contractile effect of PVAT on the underlying thoracic aorta. Nicotine also decreased the gene and protein expression of PPARγ, adiponectin, and adipoR1 in PVAT. Treatment with telmisartan restored the anti-contractile effect of PVAT and increased the gene and protein expression of PPARγ, adiponectin, and adipoR1 in PVAT. In conclusion, nicotine attenuates the anti-contractile function of PVAT through inhibition of the PPARγ-adiponectin-adipoR1 axis.

Fat and inflammation: adipocyte-myeloid cell crosstalk in atherosclerosis

Adipose tissue inflammation has been implicated in various chronic inflammatory diseases and cancer. Perivascular adipose tissue (PVAT) surrounds the aorta as an extra layer and was suggested to contribute to atherosclerosis development. PVAT regulates the function of endothelial and vascular smooth muscle cells in the aorta and represent a reservoir for various immune cells which may participate in aortic inflammation. Recent studies demonstrate that adipocytes also express various cytokine receptors and, therefore, may directly respond to inflammatory stimuli. Here we will summarize current knowledge on immune mechanisms regulating adipocyte activation and the crosstalk between myeloid cells and adipocytes in pathogenesis of atherosclerosis.

Non-Contrast and Contrast-Enhanced Cardiac Computed Tomography Imaging in the Diagnostic and Prognostic Evaluation of Coronary Artery Disease

In recent decades, cardiac computed tomography (CT) has emerged as a powerful non-invasive tool for risk stratification, as well as the detection and characterization of coronary artery disease (CAD), which remains the main cause of morbidity and mortality in the world. Advances in technology have favored the increasing use of cardiac CT by allowing better performance with lower radiation doses. Coronary artery calcium, as assessed by non-contrast CT, is considered to be the best marker of subclinical atherosclerosis, and its use is recommended for the refinement of risk assessment in low-to-intermediate risk individuals. In addition, coronary CT angiography (CCTA) has become a gate-keeper to invasive coronary angiography (ICA) and revascularization in patients with acute chest pain by allowing the assessment not only of the extent of lumen stenosis, but also of its hemodynamic significance if combined with the measurement of fractional flow reserve or perfusion imaging. Moreover, CCTA provides a unique incremental value over functional testing and ICA by imaging the vessel wall, thus allowing the assessment of plaque burden, composition, and instability features, in addition to perivascular adipose tissue attenuation, which is a marker of vascular inflammation. There exists the potential to identify the non-obstructive lesions at high risk of progression to plaque rupture by combining all of these measures.

Inflamed adipose tissue: Therapeutic targets for obesity-related endothelial injury

Cardiovascular disease is the leading cause of death worldwide and is primarily associated with obesity, visceral adiposity, and unhealthy perivascular adipose tissue. The inflammatory polarization of immune cells residing in adipose tissue and abnormal levels of adipose-related cytokines are crucial factors contributing to the pathogenesis of metabolic disorders. We reviewed the most relevant papers in the English literature regarding perivascular adipose tissue and obesity related inflammation and cardiovascular disease, aimed to explore potential therapeutic targets for metabolic alterations related to cardiovascular health. Such an understanding will help determine the pathogenetic relationship between obesity and vascular injury in efforts to ameliorate obesity-related inflammatory responses. In the context of obesity, dysregulation of adipose tissue immune function, which consists of immune cells and adipose-derived cytokines, plays a crucial role in vascular injury and endothelial dysfunction, especially the perivascular adipose tissue. Metabolic changes between typical visceral adipose tissue and perivascular adipose tissue in obese conditions would be beneficial in improving the risk of obesity-induced endothelial dysfunction and CVDs.

Mechanisms of Coronary Artery Spasm

Recent clinical trials have highlighted that percutaneous coronary intervention in patients with stable angina provides limited additional benefits on top of optimal medical therapy. This has led to much more attention being paid to coronary vasomotion abnormalities regardless of obstructive or non-obstructive arterial segments. Coronary vasomotion is regulated by multiple mechanisms that include the endothelium, vascular smooth muscle cells (VSMCs), myocardial metabolic demand, autonomic nervous system and inflammation. Over the years, several animal models have been developed to explore the central mechanism of coronary artery spasm. This review summarises the landmark studies on the mechanisms of coronary vasospasm demonstrating the central role of Rho-kinase as a molecular switch of VSMC hypercontraction and the important role of coronary adventitial inflammation for Rho-kinase upregulation in VSMCs.

Perivascular adipose tissue in vascular pathologies-a novel therapeutic target for atherosclerotic disease?

Most blood vessels are surrounded by adipose tissues known as perivascular adipose tissue (PVAT). Emerging experimental data have implicated the potential involvement of PVAT in the pathogenesis of cardiovascular disease: PVAT might be a source of inflammatory mediators under pathological conditions such as metabolic disorders, chronic inflammation, and aging, leading to vascular pathologies, while having vasculo-protective roles in a healthy state. PVAT has been also gaining attention in human disease conditions. Recent integrative omics approaches have greatly enhanced our understanding of the molecular mechanisms underlying the diverse functions of PVAT. This review summarizes recent progress in PVAT research and discusses the potential of PVAT as a target for the treatment of atherosclerosis.

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.

Perivascular adipose tissue promotes vascular dysfunction in murine lupus

Introduction

Patients with systemic lupus erythematosus (SLE) are at elevated risk for Q10 cardiovascular disease (CVD) due to accelerated atherosclerosis. Compared to heathy control subjects, lupus patients have higher volumes and densities of thoracic aortic perivascular adipose tissue (PVAT), which independently associates with vascular calcification, a marker of subclinical atherosclerosis. However, the biological and functional role of PVAT in SLE has not been directly investigated.

Methods

Using mouse models of lupus, we studied the phenotype and function of PVAT, and the mechanisms linking PVAT and vascular dysfunction in lupus disease.

Results and discussion

Lupus mice were hypermetabolic and exhibited partial lipodystrophy, with sparing of thoracic aortic PVAT. Using wire myography, we found that mice with active lupus exhibited impaired endothelium-dependent relaxation of thoracic aorta, which was further exacerbated in the presence of thoracic aortic PVAT. Interestingly, PVAT from lupus mice exhibited phenotypic switching, as evidenced by "whitening" and hypertrophy of perivascular adipocytes along with immune cell infiltration, in association with adventitial hyperplasia. In addition, expression of UCP1, a brown/beige adipose marker, was dramatically decreased, while CD45-positive leukocyte infiltration was increased, in PVAT from lupus mice. Furthermore, PVAT from lupus mice exhibited a marked decrease in adipogenic gene expression, concomitant with increased pro-inflammatory adipocytokine and leukocyte marker expression. Taken together, these results suggest that dysfunctional, inflamed PVAT may contribute to vascular disease in lupus.

Epigenetic Signatures in Arterial Hypertension: Focus on the Microvasculature

Systemic arterial hypertension (AH) is a multifaceted disease characterized by accelerated vascular aging and high cardiometabolic morbidity and mortality. Despite extensive work in the field, the pathogenesis of AH is still incompletely understood, and its treatment remains challenging. Recent evidence has shown a deep involvement of epigenetic signals in the regulation of transcriptional programs underpinning maladaptive vascular remodeling, sympathetic activation and cardiometabolic alterations, all factors predisposing to AH. After occurring, these epigenetic changes have a long-lasting effect on gene dysregulation and do not seem to be reversible upon intensive treatment or the control of cardiovascular risk factors. Among the factors involved in arterial hypertension, microvascular dysfunction plays a central role. This review will focus on the emerging role of epigenetic changes in hypertensive-related microvascular disease, including the different cell types and tissues (endothelial cells, vascular smooth muscle cells and perivascular adipose tissue) as well as the involvement of mechanical/hemodynamic factors, namely, shear stress.

Chronic intermittent hypobaric hypoxia ameliorates vascular reactivity through upregulating adiponectin expression of PVAT in metabolic syndrome rats

Cumulating evidence demonstrated that chronic intermittent hypobaric hypoxia (CIHH) had beneficial effects on the body. This study investigated the role of perivascular adipose tissue (PVAT) in ameliorating effect of CIHH on vascular reactivity by adiponectin in mesenteric artery of metabolic syndrome (MS) rats. Main methods: 6-week-old male Sprague-Dawley rats were randomly divided into four groups: control (CON), MS model, CIHH treatment, and MS + CIHH treatment group. The size of adipocytes in PVAT was measured by scanning electron microscopy. Serum adiponectin was measured. The microvessel recording technique was used to observe the effect of CIHH on contraction and relaxation in mesenteric artery rings. Also, the expressions of interleukin-1β, tumor necrosis factor-α, adiponectin, AdipoR1, AdipoR2, APPL1, and endothelial nitric oxide synthase (eNOS) were assayed by Western blotting. Key findings: in MS rats, adipocyte size increased, serum adiponectin decreased, contraction reaction increased while relaxation reaction decreased, the expression of pro-inflammatory cytokines was upregulated, while adiponectin was downregulated in PVAT, and the expressions of AdipoR1, AdipoR2, APPL, and phosphorylated-eNOS were downregulated in mesenteric artery. All aforementioned abnormalities of MS were ameliorated in MS + CIHH rats. We concluded that CIHH treatment improves vascular reactivity through upregulating adiponectin expression and downregulating pro-inflammatory cytokine expression of PVAT in MS rats.

Association Between Perivascular Adipose Tissue Density and Atherosclerosis in the Descending Thoracic Aorta

Radiodensity measured by computed tomography (CT) in Hounsfield Units (HU) is emerging as a clinical tool for detecting perivascular adipose tissue (PVAT) inflammation. In the present study, we hypothesized that PVAT radiodensity might predict the risk of descending thoracic aorta atherosclerosis. A total of 73 subjects who underwent CT angiography to investigate aortic disease were retrospectively analyzed. PVAT radiodensity, aortic complex plaque (ACP), mean plaque-burden score (MPBS), and plaque density were measured, and the association between them was analyzed. Perivascular adipose tissue radiodensity (HU) in patients with different aortic plaques grades (grade 1, 2, 3, and 4) were -93.71 ± 2.50, -93.63 ± 3.93, -90.24 ± 4.49, and -89.90 ± 5.18, respectively, and the difference was significant (P = .010). In the regression analysis, PVAT radiodensity was an independent predictor of ACP, with an OR of 1.263. In the linear analysis, PVAT radiodensity was an independent predictor of MPBS, with a β-coefficient of .073. In the univariate analysis, only the PVAT radiodensity was significantly associated with plaque density, with a β-coefficient of -1.666. In conclusion, PVAT density was independently related to descending thoracic aorta atherosclerosis.

Role of Perivascular Adipose Tissue in Aorta Reactivity from Obese and Hyperglycemic CD-1 Mice: New Insights into Perivascular Adipose Tissue

Background: Perivascular adipose tissue (PVAT) plays an essential role in cardiovascular homeostasis. However, during obesity and diabetes, its role in vascular tone regulation is unclear. This study aimed to evaluate the function of the PVAT on aorta reactivity in the lean and cafeteria (CAF) diet-induced obese-hyperglycemic mice model. Methods: Aorta reactivity to phenylephrine, KCl, and acetylcholine was analyzed in lean (n = 6) and obese mice (n = 6). Also, nitric oxide (NO-) and cyclooxygenase participation, in the presence (n = 6) and absence (n = 6) of PVAT, were examined in the aortas. Results: After a CAF diet for 19 weeks, obese mice showed increased body weight, glucose intolerance, and hypercholesterolemia concerning lean mice. Vascular reactivity to phenylephrine was reduced significantly in the aorta of obese mice. In contrast, the contraction produced by KCl (80 mM) was increased in the aorta of obese mice independent of PVAT. Acetylcholine-induced vasorelaxation diminished in the aortas of obese mice in the presence of PVAT. Nonselective inhibition of cyclooxygenases likely shows that PVAT and endothelium release vasorelaxant prostanoids. Conclusions: The results suggest that PVAT modulates aorta reactivity by releasing NO-, decreasing the α₁-adrenergic response to phenylephrine, and probably releasing vasorelaxant prostanoids. The data suggest that PVAT regulates the vascular smooth muscle and endothelial function in a CAF diet-induced obese-hyperglycemic mice model.

Thoracic perivascular adipose tissue inhibits VSMC apoptosis and aortic aneurysm formation in mice via the secretome of browning adipocytes

Abdominal aortic aneurysm (AAA) is a dangerous vascular disease without any effective drug therapies so far. Emerging evidence suggests the phenotypic differences in perivascular adipose tissue (PVAT) between regions of the aorta are implicated in the development of atherosclerosis evidenced by the abdominal aorta more vulnerable to atherosclerosis than the thoracic aorta in large animals and humans. The prevalence of thoracic aortic aneurysms (TAA) is much less than that of abdominal aortic aneurysms (AAA). In this study we investigated the effect of thoracic PVAT (T-PVAT) transplantation on aortic aneurysm formation and the impact of T-PVAT on vascular smooth muscle cells. Calcium phosphate-induced mouse AAA model was established. T-PVAT (20 mg) was implanted around the abdominal aorta of recipient mice after removal of endogenous abdominal PVAT (A-PVAT) and calcium phosphate treatment. Mice were sacrificed two weeks after the surgery and the maximum external diameter of infrarenal aorta was measured. We found that T-PVAT displayed a more BAT-like phenotype than A-PVAT; transplantation of T-PVAT significantly attenuated calcium phosphate-induced abdominal aortic dilation and elastic degradation as compared to sham control or A-PVAT transplantation. In addition, T-PVAT transplantation largely preserved smooth muscle cell content in the abdominal aortic wall. Co-culture of T-PVAT with vascular smooth muscle cells (VSMCs) significantly inhibited H2O2- or TNFα plus cycloheximide-induced VSMC apoptosis. RNA sequencing analysis showed that T-PVAT was enriched by browning adipocytes and anti-apoptotic secretory proteins. We further verified that the secretome of mature adipocytes isolated from T-PVAT significantly inhibited H2O2- or TNFα plus cycloheximide-induced VSMC apoptosis. Using proteomic and bioinformatic analyses we identified cartilage oligomeric matrix protein (COMP) as a secreted protein significantly increased in T-PVAT. Recombinant COMP protein significantly inhibited VSMC apoptosis. We conclude that T-PVAT exerts anti-apoptosis effect on VSMCs and attenuates AAA formation, which is possibly attributed to the secretome of browning adipocytes.

Insights by which TUDCA is a potential therapy against adiposity

Adipose tissue is an organ with metabolic and endocrine activity. White, brown and ectopic adipose tissues have different structure, location, and function. Adipose tissue regulates energy homeostasis, providing energy in nutrient-deficient conditions and storing it in high-supply conditions. To attend to the high demand for energy storage during obesity, the adipose tissue undergoes morphological, functional and molecular changes. Endoplasmic reticulum (ER) stress has been evidenced as a molecular hallmark of metabolic disorders. In this sense, the ER stress inhibitor tauroursodeoxycholic acid (TUDCA), a bile acid conjugated to taurine with chemical chaperone activity, has emerged as a therapeutic strategy to minimize adipose tissue dysfunction and metabolic alterations associated with obesity. In this review, we highlight the effects of TUDCA and receptors TGR5 and FXR on adipose tissue in the setting of obesity. TUDCA has been demonstrated to limit metabolic disturbs associated to obesity by inhibiting ER stress, inflammation, and apoptosis in adipocytes. The beneficial effect of TUDCA on perivascular adipose tissue (PVAT) function and adiponectin release may be related to cardiovascular protection in obesity, although more studies are needed to clarify the mechanisms. Therefore, TUDCA has emerged as a potential therapeutic strategy for obesity and comorbidities.

Trends in perivascular macrophages research from 1997 to 2021: A bibliometric analysis

INTRODUCTION

Perivascular macrophages (PVMs) play pivotal roles in maintaining the physiological function of the brain. Dysfunction of PVMs is emerging as an important mechanism in various disease conditions in the brain.

METHODS

In this work, we analyzed recent research advances in PVMs, especially in the brain, from the Web of Science (WoS) core database using bibliometric analysis based on the search terms "perivascular macrophages" and "perivascular macrophage" on October 27, 2021. Visualization and collaboration analysis were performed by Citespace (5.8 R3 mac).

RESULTS

We found 2384 articles published between 1997 and 2021 in the field of PVMs, which were selected for analysis. PVMs were involved in several physio-pathological fields, in which Neurosciences and Neurology, Neuroscience, Immunology, Pathology, and Cardiovascular System and Cardiology were most reported. The research focuses on PVMs mainly in the central nervous system (CNS), inflammation, macrophage or T-cell, and disease, and highlights the related basic research regarding its activation, oxidative stress, angiotensin II, and insulin resistance. Tumor-associated macrophage, obesity, myeloid cell, and inflammation were relatively recent highlight keywords that attracted increasing attention in recent years. Harvard Univ, Vrije Univ Amsterdam, occupied important positions in the research field of PVMs. Meanwhile, PVM research in China (Peking Univ, Sun Yat Sen Univ, Shanghai Jiao Tong Univ, and Shandong Univ) is on the rise. Cluster co-citation analysis revealed that the mechanisms of CNS PVMs and related brain diseases are major specialties associated with PVMs, while PVMs in perivascular adipose tissue and vascular diseases or obesity are another big category of PVMs hotspots.

CONCLUSION

In conclusion, the research on PVMs continues to deepen, and the hotspots are constantly changing. Future studies of PVMs could have multiple disciplines intersecting.

Pericoronary fat attenuation index is associated with plaque parameters and stenosis severity in patients with acute coronary syndrome: a cross-sectional study

Background

The pericoronary fat attenuation index (FAI) is a novel imaging biomarker of coronary inflammation, which is closely related to development and progression of coronary artery disease (CAD). However, there are limited reports on whether elevated pericoronary FAI values from coronary computed tomography angiography (CCTA) were associated with plaque parameters and coronary stenosis in patients with acute coronary syndrome (ACS). We aimed to assessed that FAI helps to identify high risk of CAD.

Methods

The clinical diagnosis confirmed to the American Heart Association guidelines for ACS. The lesion-specific pericoronary FAI and plague parameters were measured using QAngioCT software. Using a Hounsfield unit (HU) of -70.1 as the threshold value, lesions with a lesion-specific pericoronary FAI value ≥-70.1 HU were allocated to the FAI-positive group and those with a FAI value <-70.1 HU were allocated to the FAI-negative group. The patients were divided into four stenosis groups according to the coronary angiography (CAG) results, and differences in the FAI values among the four groups were analyzed.

Results

A retrospective analysis of 127 ACS patients, including 299 lesions, who underwent CCTA and CAG successively was conducted. The prevalence of vulnerable plaques increased significantly in the FAI-positive group (49.35% vs. 23.87%, P<0.001). The area under the curve (AUC) of FAI in the diagnosis of vulnerable plagues was 0.810. Plaques were closer to the coronary ostium [3.32 (2.83, 4.29) vs. 4.17 (3.33, 4.95) cm, P<0.001] and more often located in the bifurcated segments of the vessels (50.65% vs. 32.43%, P=0.004) in the FAI-positive group than the FAI-negative group. The FAI-positive group also had a higher percentage of diameter stenosis than the FAI-negative group [80.00% (65.00%, 90.00%) vs. 60.00% (40.00%, 85.00%), P<0.001]. FAI values were higher in stenoses with a diameter ≥50% than stenoses with a diameter <50%.

Conclusions

The FAI was identified as a novel imaging biomarker of coronary inflammation that is correlated with vulnerable plaque features and stenosis severity.

Bone morphogenetic protein 4 in perivascular adipose tissue ameliorates hypertension through regulation of angiotensinogen

BACKGROUND

Perivascular adipose tissue (PVAT), an active endocrine organ, exerts direct effect on vascular tone through paracrine. Activation of PVAT metabolism plays an inhibitory role in atherosclerosis via secreting relaxing factors. The present studies were designed to investigate the role of PVAT metabolism in regulation of hypertension.

MATERIALS AND METHODS

Apolipoprotein E (ApoE) knockout mice with BMP4 knockout in adipose tissue or brown adipose tissue (aP2-DKO or UCP1-DKO, respectively) were used for exploring the role of impaired PVAT metabolism in hypertension. Vascular function was assessed using wire myography. The potential regulatory factor of vascular function was explored using qPCR and ELISA and further confirmed in perivascular fat cell line.

RESULTS

Knockout of BMP4 either in adipose tissue or specifically in BAT aggravates high-fat diet (HFD, 40% fat)-induced hypertension and endothelial dysfunction in ApoE-/- mice. In the meanwhile, deficiency of BMP4 also aggravates Ang II (angiotensin II) -induced hypertension and vascular remodeling in ApoE-/- mice. Moreover, deficiency of BMP4 inhibits NO release and induces ROS production. In vitro system, aortic rings pretreated with PVAT extracts from BMP4-DKO mice showed increased vasoconstriction and reduced endothelial-dependent relaxation compared with the controls. We further demonstrated that PVAT of BMP4-DKO mice expressed higher level of angiotensinogen (AGT) and Ang II compared with the controls.

CONCLUSION

Impaired PVAT metabolism aggravates hypertension, and this effect is dependent on the activation of local renin-angiotensin-aldosterone system (RAAS). The results of this study first demonstrate the regulatory role of PVAT metabolism in hypertension.

Endothelium-Derived Relaxing Factors and Endothelial Function: A Systematic Review

BACKGROUND

The endothelium plays a pivotal role in homeostatic mechanisms. It specifically modulates vascular tone by releasing vasodilatory mediators, which act on the vascular smooth muscle. Large amounts of work have been dedicated towards identifying mediators of vasodilation and vasoconstriction alongside the deleterious effects of reactive oxygen species on the endothelium. We conducted a systematic review to study the role of the factors released by the endothelium and the effects on the vessels alongside its role in atherosclerosis.

METHODS

A search was conducted with appropriate search terms. Specific attention was offered to the effects of emerging modulators of endothelial functions focusing the analysis on studies that investigated the role of reactive oxygen species (ROS), perivascular adipose tissue, shear stress, AMP-activated protein kinase, potassium channels, bone morphogenic protein 4, and P2Y2 receptor.

RESULTS

530 citations were reviewed, with 35 studies included in the final systematic review. The endpoints were evaluated in these studies which offered an extensive discussion on emerging modulators of endothelial functions. Specific factors such as reactive oxygen species had deleterious effects, especially in the obese and elderly. Another important finding included the shear stress-induced endothelial nitric oxide (NO), which may delay development of atherosclerosis. Perivascular Adipose Tissue (PVAT) also contributes to reparative measures against atherosclerosis, although this may turn pathological in obese subjects. Some of these factors may be targets for pharmaceutical agents in the near future.

CONCLUSION

The complex role and function of the endothelium is vital for regular homeostasis. Dysregulation may drive atherogenesis; thus, efforts should be placed at considering therapeutic options by targeting some of the factors noted.

[Ectopic obesity in patients without manifested cardiovascular disease: regulations, frequency and clinical characteristics]

AIM

To determine the frequency, distribution and characteristics of ectopic obesity in patients without manifested cardiovascular disease.

MATERIALS AND METHODS

We examined 320 patients without manifested cardiovascular disease (average age 63.813.9 years), 38 of them without cardiovascular risk factors (healthy referent group). Anthropometric indicators were measured, body mass index (BMI) was calculated. Degree, type of obesity, lipid profile were evaluated. All patients underwent multi-detector chest computed tomography in spiral mode on Toshiba Aquilion Prime scanner using standardized protocol. Perivascular adipose tissue (PVAT) and pericardial adipose tissue (PAT) were detected using specialized semi-automatic software Tissue Composition Module QCTPro (Mindways Software, Inc., USA) after scanner calibration with special phantom. PAT and PVAT exceeding the 90th percentile in the healthy referent group were considered as ectopic obesity. Statistical analysis was performed using Statistica 10.0 software (StatSoft Inc., USA).

RESULTS

PAT volume 3.2 cm3 and PVAT volume 0.4 cm3 were criteria for high pericardial and high perivascular fat; 81 (25.2%) patients had ectopic obesity, 85 (26.5%) patients abdominal obesity; 146 (42.9%) people had high pericardial fat, 134 (39.4%) high perivascular fat. The frequency of ectopic obesity in patients with arterial hypertension (AH) was statistically significantly higher compared to persons without AH. Significantly more often ectopic forms of obesity were detected in patients with overweight and obesity. The high pericardial fat and high perivascular fat were found in patients with overweight and normal body weight. When comparing the clinical characteristics of patients with abdominal and ectopic obesity, metabolic parameters, as well as the incidence of hypertension and dyslipidemia, did not differ significantly.

CONCLUSION

Ectopic obesity can develop outside of global obesity. In addition, this type of obesity is accompanied by metabolic disorders and AH, regardless of the abdominal distribution of adipose tissue.

Dahl Salt-Resistant Rat Is Protected against Hypertension during Diet-Induced Obesity

A high-fat diet (HFD) frequently causes obesity-induced hypertension. Because Dahl salt-resistant rats are protected against hypertension after high-salt or high-fructose intake, it is of interest whether this model also protects against hypertension after diet-induced obesity. We tested the hypothesis that Dahl salt-resistant rat protects against hypertension during diet-induced obesity. Dahl salt-sensitive (SS) and Dahl salt-resistant (SR) rats were fed a HFD (60% fat) or a chow diet (CD; 8% fat) for 12 weeks. We measured blood pressure using the tail-cuff method. The paraffin sections of thoracic perivascular adipose tissue (tPVAT) were stained with hematoxylin/eosin and trichrome. The expression of genes in the tPVAT and kidneys were measured by reverse transcription-quantitative polymerase chain reaction. The HFD induced hypertension in SS (p < 0.01) but not SR rats, although it increased body weight gain (p < 0.05) and tPVAT weight (p < 0.01) in both rats. The HFD did not affect the expression of genes related to any of the adipocyte markers in both rats, although SR rats had reduced beige adipocyte marker Tmem26 levels (p < 0.01) and increased anti-inflammatory cytokine adiponectin (p < 0.05) as compared with SS rat. The HFD did not affect the mRNA expression of contractile factors in the tPVAT of SS and SR rats. SR rats are protected against hypertension during diet-induced obesity. This result implies that the genetic trait determining salt sensitivity may also determine fructose and fat sensitivity and that it is associated with the prevention of hypertension.

Conductance Artery Wall Layers and Their Respective Roles in the Clearance Functions

Evolutionary organization of the arterial wall into layers occurred concomitantly with the emergence of a highly muscularized, pressurized arterial system that facilitates outward hydraulic conductance and mass transport of soluble substances across the arterial wall. Although colliding circulating cells disperse potential energy within the arterial wall, the different layers counteract this effect: (1) the endothelium ensures a partial barrier function; (2) the media comprises smooth muscle cells capable of endocytosis/phagocytosis; (3) the outer adventitia and perivascular adipocytic tissue are the final receptacles of convected substances. While the endothelium forms a physical and a biochemical barrier, the medial layer is avascular, relying on the specific permeability properties of the endothelium for metabolic support. Different components of the media interact with convected molecules: medial smooth muscle cells take up numerous molecules via scavenger receptors and are capable of phagocytosis of macro/micro particles. The outer layers-the highly microvascularized innervated adventitia and perivascular adipose tissue-are also involved in the clearance functions of the media: the adventitia is the seat of immune response development, inward angiogenesis, macromolecular lymphatic drainage, and neuronal stimulation. Consequently, the clearance functions of the arterial wall are physiologically essential, but also may favor the development of arterial wall pathologies. This review describes how the walls of large conductance arteries have acquired physiological clearance functions, how this is determined by the attributes of the endothelial barrier, governed by endocytic and phagocytic capacities of smooth muscle cells, impacting adventitial functions, and the role of these clearance functions in arterial wall diseases.

Exosomes facilitate intercellular communication between uterine perivascular adipose tissue and vascular smooth muscle cells in pregnant rats

Perivascular adipose tissue (PVAT) is distinct from other adipose depots as it has differential gene and protein profiles and vasoactive functions. We have shown that pregnancy affects the morphology of PVAT surrounding the uterine arteries (utPVAT) differentially than the morphology of non-perivascular reproductive adipose depots (i.e., periovarian adipose tissue, OVAT). Here, we hypothesized that pregnancy modifies the profile (size and molecular weight) of exosome-like extracellular vesicles released by utPVAT (Exo-utPVAT) compared to OVAT (Exo-OVAT) and that primary uterine vascular smooth muscle cells (utVSMCs) can internalize Exo-utPVAT. Our findings indicate that utPVAT from pregnant and non-pregnant rats secrete exosome-like vesicles. Exo-utPVAT from pregnant rats were smaller (i.e., molecular size) and heavier (i.e., molecular weight) than those from non-pregnant rats, while pregnancy did not affect the size of Exo-OVAT. Immunocytochemistry and confocal microscopy showed that primary utVSMCs internalized Exo-utPVAT (both tissues from the same pregnant rat) labeled by the lipophilic tracer DiO. Treatment of isolated uterine arteries with Exo-utPVAT did not affect relaxation responses to acetylcholine (ACh) in pregnant or non-pregnant rats. Collectively, these findings demonstrate a novel type of intercellular communication between Exo-utPVAT and utVSMCs and indicate pregnancy modulates the morphology and cargo of Exo-utPVAT.

The Role of Perivascular Adipose Tissue-Derived Hydrogen Sulfide in the Control of Vascular Homeostasis

Significance: Emerging evidence suggests that perivascular adipose tissue (PVAT) has a relevant role in the control of vascular tone in physiology and pathology. Healthy PVAT has anticontractile, anti-inflammatory, and antioxidative actions. Accumulating data from both human and experimental animal models indicate that PVAT dysfunction is conceivably coupled to cardiovascular diseases, and it is associated with vascular inflammation, oxidative stress, and arterial remodeling. Therefore, "healthy" PVAT may constitute a novel therapeutic target for the prevention and treatment of cardiovascular diseases. Recent Advances: Hydrogen sulfide (H₂S) has been recognized as a vascular anti-contractile factor released from PVAT. The enzymes deputed to H₂S biosynthesis are variously expressed in PVAT and strictly dependent on the vascular bed and species. Metabolic and cardiovascular diseases can alter the morphological and secretory characteristics of PVAT, influencing also the H₂S signaling. Here, we discuss the role of PVAT-derived H₂S in healthy conditions and its relevance in alterations occurring in vascular disorders. Critical Issues: We discuss how a better understanding may help in the prevention of vascular dysfunction related to alteration in PVAT-released H₂S as well as the importance of the interplay between PVAT and H₂S. Future Directions: We propose future directions to evaluate the contribution of each enzyme involved in H₂S biosynthesis and their alteration/switch occurring in vascular disorders and the remaining challenges in investigating the role of H₂S. Antioxid. Redox Signal. 37, 84-97.

EGR1 and KLF4 as Diagnostic Markers for Abdominal Aortic Aneurysm and Associated With Immune Infiltration

Background

Formation and rupture of abdominal aortic aneurysm (AAA) is fatal, and the pathological processes and molecular mechanisms underlying its formation and development are unclear. Perivascular adipose tissue (PVAT) has attracted extensive attention as a newly defined secretory organ, and we aim to explore the potential association between PVAT and AAA.

Methods

We analyzed gene expression and clinical data of 30 PVAT around AAA and 30 PVAT around normal abdominal aorta (NAA). The diagnostic markers and immune cell infiltration of PVAT were further investigated by WGCNA, CIBERSORT, PPI, and multiple machine learning algorisms (including LASSO, RF, and SVM). Subsequently, eight-week-old C57BL/6 male mice (n = 10) were used to construct AAA models, and aorta samples were collected for molecular validation. Meanwhile, fifty-five peripheral venous blood samples from patients (AAA vs. normal: 40:15) in our hospital were used as an inhouse cohort to validate the diagnostic markers by qRT-PCR. The diagnostic efficacy of biomarkers was assessed by receiver operating characteristic (ROC) curve, area under the ROC (AUC), and concordance index (C-index).

Results

A total of 75 genes in the Grey60 module were identified by WGCNA. To select the genes most associated with PVAT in the grey60 module, three algorithms (including LASSO, RF, and SVM) and PPI were applied. EGR1 and KLF4 were identified as diagnostic markers of PVAT, with high accurate AUCs of 0.916, 0.926, and 0.948 (combined two markers). Additionally, the two biomarkers also displayed accurate diagnostic efficacy in the mice and inhouse cohorts, with AUCs and C-indexes all >0.8. Compared with the NAA group, PVAT around AAA was more abundant in multiple immune cell infiltration. Ultimately, the immune-related analysis revealed that EGR1 and KLF4 were associated with mast cells, T cells, and plasma cells.

Conclusion

EGR1 and KLF4 were diagnostic markers of PVAT around AAA and associated with multiple immune cells.

Aging Affects KV7 Channels and Perivascular Adipose Tissue-Mediated Vascular Tone

Aging is an independent risk factor for hypertension, cardiovascular morbidity, and mortality. However, detailed mechanisms linking aging to cardiovascular disease are unclear. We studied the aging effects on the role of perivascular adipose tissue and downstream vasoconstriction targets, voltage-dependent K_V7 channels, and their pharmacological modulators (flupirtine, retigabine, QO58, and QO58-lysine) in a murine model. We assessed vascular function of young and old mesenteric arteries in vitro using wire myography and membrane potential measurements with sharp electrodes. We also performed bulk RNA sequencing and quantitative reverse transcription-polymerase chain reaction tests in mesenteric arteries and perivascular adipose tissue to elucidate molecular underpinnings of age-related phenotypes. Results revealed impaired perivascular adipose tissue-mediated control of vascular tone particularly via K_V7.3–5 channels with increased age through metabolic and inflammatory processes and release of perivascular adipose tissue-derived relaxation factors. Moreover, QO58 was identified as novel pharmacological vasodilator to activate XE991-sensitive KCNQ channels in old mesenteric arteries. Our data suggest that targeting inflammation and metabolism in perivascular adipose tissue could represent novel approaches to restore vascular function during aging. Furthermore, K_V7.3–5 channels represent a promising target in cardiovascular aging.

Comparative Proteomic Analysis of tPVAT during Ang II Infusion

Perivascular adipose tissue (PVAT) homeostasis plays an important role in maintaining vascular function, and PVAT dysfunction may induce several pathophysiological situations. In this study, we investigated the effect and mechanism of the local angiotensin II (Ang II) on PVAT. High-throughput comparative proteomic analysis, based on TMT labeling combined with LC-MS/MS, were performed on an in vivo Ang II infusion mice model to obtain a comprehensive view of the protein ensembles associated with thoracic PVAT (tPVAT) dysfunction induced by Ang II. In total, 5037 proteins were confidently identified, of which 4984 proteins were quantified. Compared with the saline group, 145 proteins were upregulated and 146 proteins were downregulated during Ang II-induced tPVAT pathogenesis. Bioinformatics analyses revealed that the most enriched GO terms were annotated as gene silencing, monosaccharide binding, and extracellular matrix. In addition, some novel proteins, potentially associated with Ang II infusion, were identified, such as acyl-CoA carboxylase α, very long-chain acyl-CoA synthetase (ACSVL), uncoupling protein 1 (UCP1), perilipin, RAS protein-specific guanine nucleotide-releasing factor 2 (RasGRF2), and hypoxia inducible factor 1α (HIF-1α). Ang II could directly participate in the regulation of lipid metabolism, transportation, and adipocyte differentiation by affecting UCP1 and perilipin. Importantly, the key KEGG pathways were involved in fatty acid biosynthesis, FABP3-PPARα/γ, RasGRF2-ERK-HIF-1α, RasGRF2-PKC-HIF-1α, and STAT3-HIF-1α axis. The present study provided the most comprehensive proteome profile of mice tPVAT and some novel insights into Ang II-mediated tPVAT dysfunction and will be helpful for understanding the possible relationship between local RAS activation and PVAT dysfunction.

Ovariectomy Causes Degeneration of Perivascular Adipose Tissue

Women are more resistant than men to the development of vascular diseases. However, menopause is a factor leading to deterioration of female vascular integrity, and it is reported that the risk of vascular diseases such as atherosclerosis and abdominal aortic aneurysm is increased in postmenopausal women. Although it is suggested that perivascular adipose tissue (PVAT) is deeply involved in the increased risk of vascular disease development, the effect of menopause on PVAT integrity is unknown. In this study, we aimed to elucidate the effect of menopause on PVAT in ovariectomized (OVX) rats. PVAT was divided into 4 regions based on characteristics. Hypertrophy and increased inflammation of adipocytes in the PVAT were observed in the OVX group, but the effects of OVX were different for each region. OVX induced matrix metalloproteinase (MMP) -9 which degrade extracellular matrix such as elastin and collagen fibers in PVAT. Degeneration of the arterial fibers of the thoracic and abdominal aorta were observed in the OVX group. These results indicate that OVX can cause dysfunction of PVAT which can cause degradation of arterial fibers. Appropriate management of PVAT may play an important role in the prevention and treatment of diseases originating from ovarian hypofunction.

Perivascular fat imaging by computed tomography (CT): a virtual guide

Imaging in medicine has been revolutionised by technological, computational and research advances over the past decades. Computed tomography (CT), in particular, has seen rapid evolution especially in the field of cardiovascular non-invasive imaging. It is being recognised as the first-line tool for the assessment of stable and unstable disease with diagnostic, prognostic and re-stratification potential. Vascular inflammation is a key component of the atherosclerotic process and has been shown to induce molecular, transcriptional and structural changes to perivascular adipose tissue (PVAT). Being a diverse structure itself, PVAT surrounds the human vessels and is characterised by a highly rich secretome, including, amongst others, adipokines, cytokines, gaseous messengers and miRNAs It is implicated in a bidirectional interplay with the adjacent vascular wall, affecting and being affected by aspects of its biology, mainly inflammation. In this review, we discuss the current status of cardiac CT in imaging vascular inflammation through PVAT phenotyping. LINKED ARTICLES: This article is part of a themed issue on Molecular imaging - visual themed issue. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.21/issuetoc.

The Role of Obesity-Induced Perivascular Adipose Tissue (PVAT) Dysfunction in Vascular Homeostasis

Perivascular adipose tissue (PVAT) is an additional special type of adipose tissue surrounding blood vessels. Under physiological conditions, PVAT plays a significant role in regulation of vascular tone, intravascular thermoregulation, and vascular smooth muscle cell (VSMC) proliferation. PVAT is responsible for releasing adipocytes-derived relaxing factors (ADRF) and perivascular-derived relaxing factors (PDRF), which have anticontractile properties. Obesity induces increased oxidative stress, an inflammatory state, and hypoxia, which contribute to PVAT dysfunction. The exact mechanism of vascular dysfunction in obesity is still not well clarified; however, there are some pathways such as renin-angiotensin-aldosterone system (RAAS) disorders and PVAT-derived factor dysregulation, which are involved in hypertension and endothelial dysfunction development. Physical activity has a beneficial effect on PVAT function among obese patients by reducing the oxidative stress and inflammatory state. Diet, which is the second most beneficial non-invasive strategy in obesity treatment, may have a positive impact on PVAT-derived factors and may restore the balance in their concentration.

The Role of Perivascular Adipose Tissue in Early Changes in Arterial Function during High-Fat Diet and Its Combination with High-Fructose Intake in Rats

The aim of the current study was to evaluate the influence of a high-fat diet and its combination with high-fructose intake on young normotensive rats, with focus on the modulatory effect of perivascular adipose tissue (PVAT) on the reactivity of isolated arteries. Six-week-old Wistar–Kyoto rats were treated for 8 weeks with a control diet (10% fat), a high-fat diet (HFD; 45% fat), or a combination of the HFD with a 10% solution of fructose. Contractile and relaxant responses of isolated rat arteries, with preserved and removed PVAT for selected vasoactive stimuli, were recorded isometrically by a force displacement transducer. The results demonstrated that, in young rats, eight weeks of the HFD might lead to body fat accumulation and early excitation of the cardiovascular sympathetic nervous system, as shown by increased heart rate and enhanced arterial contractile responses induced by endogenous noradrenaline released from perivascular sympathetic nerves. The addition of high-fructose intake deteriorated this state by impairment of arterial relaxation and resulted in mild elevation of systolic blood pressure; however, the increase in arterial neurogenic contractions was not detected. The diet-induced alterations in isolated arteries were observed only in the presence of PVAT, indicating that this structure is important in initiation of early vascular changes during the development of metabolic syndrome.

Effects of High-Fat and High-Fat/High-Sucrose Diet-Induced Obesity on PVAT Modulation of Vascular Function in Male and Female Mice

Increased adiposity in perivascular adipose tissue (PVAT) has been related to vascular dysfunction. High-fat (HF) diet-induced obesity models are often used to analyze the translational impact of obesity, but differences in sex and Western diet type complicate comparisons between studies. The role of PVAT was investigated in small mesenteric arteries (SMAs) of male and female mice fed a HF or a HF plus high-sucrose (HF + HS) diet for 3 or 5 months and compared them to age/sex-matched mice fed a chow diet. Vascular responses of SMAs without (PVAT-) or with PVAT (PVAT+) were evaluated. HF and HF + HS diets increased body weight, adiposity, and fasting glucose and insulin levels without affecting blood pressure and circulating adiponectin levels in both sexes. HF or HF + HS diet impaired PVAT anticontractile effects in SMAs from females but not males. PVAT-mediated endothelial dysfunction in SMAs from female mice after 3 months of a HF + HS diet, whereas in males, this effect was observed only after 5 months of HF + HS diet. However, PVAT did not impact acetylcholine-induced relaxation in SMAs from both sexes fed HF diet. The findings suggest that the addition of sucrose to a HF diet accelerates PVAT dysfunction in both sexes. PVAT dysfunction in response to both diets was observed early in females compared to age-matched males suggesting a susceptibility of the female sex to PVAT-mediated vascular complications in the setting of obesity. The data illustrate the importance of the duration and composition of obesogenic diets for investigating sex-specific treatments and pharmacological targets for obesity-induced vascular complications.

Perivascular Adipose-Derived Exosomes Reduce Foam Cell Formation by Regulating Expression of Cholesterol Transporters

Background: Accumulating evidence demonstrates that perivascular adipose tissue (PVAT) plays an important role in maintaining vascular homeostasis. The formation of macrophage foam cells is a central feature of atherosclerosis. This study aimed to evaluate the effect of PVAT-derived exosomes (EXOs) on the lipid accumulation of macrophages and verify the anti-atherogenic characteristics of PVAT.

Methods and Results: We extracted EXOs from the PVAT and subcutaneous adipose tissue (SCAT) of wild-type C57BL/6J mice. After coincubation, the EXOs were taken up by RAW264.7 cells. Oil Red O staining revealed that macrophage foam cell formation and intracellular lipid accumulation were ameliorated by PVAT-EXOs. Flow cytometry showed that PVAT-EXOs significantly reduced macrophage uptake of fluorescence-labelled oxidised low-density lipoprotein (ox-LDL). In addition, high-density lipoprotein-induced cholesterol efflux was promoted by PVAT-EXOs. Western blot analysis showed the downregulation of macrophage scavenger receptor A and the upregulation of ATP-binding cassette transporter A1 and ATP-binding cassette transporter G1, which could be mediated by the overexpression of peroxisome proliferator-activated receptor γ and was independent of liver X receptor α.

Conclusion: Our findings suggest that PVAT-EXOs reduce macrophage foam cell formation by regulating the expression of cholesterol transport proteins, which provides a novel mechanism by which PVAT protects the vasculature from atherosclerosis.

Mechanisms of abdominal aortic aneurysm progression: A review

Abdominal aortic aneurysm (AAA) is a common disease associated with significant cardiovascular morbidity and mortality. Up to now, there is still controversy on the choice of treatment method of AAA. Even so, the mechanisms of AAA progression are poorly defined, making targeting new therapies problematic. Current evidence favors an interaction of the hemodynamic microenvironment with local and systemic immune responses. In this review, we aim to provide an update of mechanisms in AAA progression, involving hemodynamics, perivascular adipose tissue, adventitial fibroblasts, vasa vasorum remodeling, intraluminal thrombus, and distribution of macrophage subtypes.

Perivascular adipose tissue and microvascular endothelial dysfunction in obese mice: Beneficial effects of aerobic exercise in adiponectin receptor (AdipoR1) and peNOSSer1177

In the present study, we aim to investigate the effects of aerobic physical training on perivascular adipose tissue (PVAT)-induced microvascular dysfunction of the femoral artery in obese mice. Microvascular reactivity was evaluated in control sedentary (c-SD), obese sedentary (o-SD) and obese trained (o-TR) male mice (C57BL6/JUnib), in the absence (PVAT-) or the presence (PVAT+) of femoral artery PVAT. We also analyzed protein expression, vascular nitric oxide (NO) production and reactive oxygen species (ROS) generation in PVAT. The blood glucose, triglycerides and total cholesterol levels were increased in the o-SD group, when compared with the c-SD group. The maximal responses and the potency to acetylcholine (ACh) were decreased in PVAT+ compared with PVAT- rings in the o-SD group, accompanied by a decrease in vascular protein expression of peNOS_Ser1177 , Cu/Zn-SOD, leptin receptor (Ob-R) and adiponectin receptor (AdipoR1). The protein expression of leptin increased and that of adiponectin decreased in PVAT. Additionally, vascular NO production was reduced and ROS generation was enhanced in PVAT in the o-SD group. Aerobic exercise training was effective for normalizing ACh relaxation response, vascular NO production and ROS generation in the o-TR group. It partially re-established the vascular protein expression of peNOS_Ser1177 and the PVAT leptin; normalized the vascular Cu/Zn-SOD and AdipoR1 protein expressions. In obese sedentary mice, the presence of PVAT is involved in the process of microvascular dysfunction of the femoral artery in a pathway associated with increased inflammation and ROS generation. The aerobic exercise training normalized the vascular response, the NO production and/or bioavailability and oxidative stress, with improved vascular expressions of Cu/Zn-SOD, peNOS_ser1177 , and AdipoR1.

Role of Perivascular Adipose Tissue and Exercise on Arterial Function with Obesity

Adipose tissue and arterial dysfunction are common in the obese state. Perivascular adipose tissue (PVAT) plays an important role in mediating arterial health, and with obesity, the PVAT dysfunction negatively affects arterial health. Exercise training exerts direct and beneficial effects on PVAT, providing an additional and novel pathway by which exercise can improve arterial health in diseased populations.

Systemic Administration of Insulin Receptor Antagonist Results in Endothelial and Perivascular Adipose Tissue Dysfunction in Mice

Hyperglycemia linked to diabetes results in endothelial dysfunction. In the present work, we comprehensively characterized effects of short-term hyperglycemia induced by administration of an insulin receptor antagonist, the S961 peptide, on endothelium and perivascular adipose tissue (PVAT) in mice. Endothelial function of the thoracic and abdominal aorta in 12-week-old male C57Bl/6Jrj mice treated for two weeks with S961 infusion via osmotic pumps was assessed in vivo using magnetic resonance imaging and ex vivo by detection of nitric oxide (NO) production using electron paramagnetic resonance spectroscopy. Additional methods were used to analyze PVAT, aortic segments and endothelial-specific plasma biomarkers. Systemic disruption of insulin signaling resulted in severe impairment of NO-dependent endothelial function and a loss of vasoprotective function of PVAT affecting the thoracic as well as abdominal parts of the aorta, however a fall in adiponectin expression and decreased uncoupling protein 1-positive area were more pronounced in the thoracic aorta. Results suggest that dysfunctional PVAT contributes to vascular pathology induced by altered insulin signaling in diabetes, in the absence of fat overload and obesity.