Obesity-Related Perivascular Adipose Tissue Damage Is Reversed by Sustained Weight Loss in the Rat

Perivascular fat tissue and vascular aging: A sword and a shield

The understanding of the function of perivascular adipose tissue (PVAT) in vascular aging has significantly changed due to the increasing amount of information regarding its biology. Adipose tissue surrounding blood vessels is increasingly recognized as a key regulator of vascular disorders. It has significant endocrine and paracrine effects on the vasculature and is mediated by the production of a variety of bioactive chemicals. It also participates in a number of pathological regulatory processes, including oxidative stress, immunological inflammation, lipid metabolism, vasoconstriction, and dilation. Mechanisms of homeostasis and interactions between cells at the local level tightly regulate the function and secretory repertoire of PVAT, which can become dysregulated during vascular aging. The PVAT secretion group changes from being reducing inflammation and lowering cholesterol to increasing inflammation and increasing cholesterol in response to systemic or local inflammation and insulin resistance. In addition, the interaction between the PVAT and the vasculature is reciprocal, and the biological processes of PVAT are directly influenced by the pertinent indicators of vascular aging. The architectural and biological traits of PVAT, the molecular mechanism of crosstalk between PVAT and vascular aging, and the clinical correlation of vascular age-related disorders are all summarized in this review. In addition, this paper aims to elucidate and evaluate the potential benefits of therapeutically targeting PVAT in the context of mitigating vascular aging. Furthermore, it will discuss the latest advancements in technology used for targeting PVAT.

Deletion of adipocyte NOS3 potentiates high-fat diet-induced hypertension and vascular remodelling via chemerin

AIMS

Obesity is an epidemic that is a critical contributor to hypertension and other cardiovascular diseases. Current paradigms suggest that endothelial nitric oxide synthase (eNOS/NOS3) in the vessel wall is the primary regulator of vascular function and blood pressure. However, recent studies have revealed the presence of eNOS/NOS3 in the adipocytes of white adipose tissues and perivascular adipose tissues (PVATs). The current understanding of the role of adipocyte NOS3 is based mainly on studies using global knockout models. The present study aimed to elucidate the functional significance of adipocyte NOS3 for vascular function and blood pressure control.

METHODS AND RESULTS

We generated an adipocyte-specific NOS3 knockout mouse line using adiponectin promoter-specific Cre-induced gene inactivation. Control and adipocyte-specific NOS3 knockout (A-NOS3 KO) mice were fed a high-fat diet (HFD). Despite less weight gain, A-NOS3 KO mice exhibited a significant increase in blood pressure after HFD feeding, associated with exacerbated vascular dysfunction and remodelling. A-NOS3 KO mice also showed increased expression of signature markers of inflammation and hypoxia in the PVATs. Among the differentially expressed adipokines, we have observed an upregulation of a novel adipokine, chemerin, in A-NOS3 KO mice. Chemerin was recently reported to link obesity and vascular dysfunction. Treatment with chemerin neutralizing antibody normalized the expression of remodelling markers in the aorta segments cultured in serum from HFD-fed A-NOS3 KO mice ex vivo.

CONCLUSION

These data suggest that NOS3 in adipocytes is vital in maintaining vascular homeostasis; dysfunction of adipocyte NOS3 contributes to obesity-induced vascular remodelling and hypertension.

The Role of Perivascular Adipose Tissue in the Pathogenesis of Endothelial Dysfunction in Cardiovascular Diseases and Type 2 Diabetes Mellitus

Cardiovascular diseases (CVDs) and type 2 diabetes mellitus (T2DM) are two of the four major chronic non-communicable diseases (NCDs) representing the leading cause of death worldwide. Several studies demonstrate that endothelial dysfunction (ED) plays a central role in the pathogenesis of these chronic diseases. Although it is well known that systemic chronic inflammation and oxidative stress are primarily involved in the development of ED, recent studies have shown that perivascular adipose tissue (PVAT) is implicated in its pathogenesis, also contributing to the progression of atherosclerosis and to insulin resistance (IR). In this review, we describe the relationship between PVAT and ED, and we also analyse the role of PVAT in the pathogenesis of CVDs and T2DM, further assessing its potential therapeutic target with the aim of restoring normal ED and reducing global cardiovascular risk.

Role of dysfunctional peri-organ adipose tissue in metabolic disease

Metabolic disease is a complex disorder defined by a group with interrelated factors. There is growing evidence that obesity can lead to a variety of metabolic diseases, including diabetes and cardiovascular disease. Excessive adipose tissue (AT) deposition and ectopic accumulation can lead to increased peri-organ AT thickness. Dysregulation of peri-organ (perivascular, perirenal, and epicardial) AT is strongly associated with metabolic disease and its complications. The mechanisms include secretion of cytokines, activation of immunocytes, infiltration of inflammatory cells, involvement of stromal cells, and abnormal miRNA expression. This review discusses the associations and mechanisms by which various types of peri-organ AT affect metabolic diseases while addressing it as a potential future treatment strategy.

Perivascular Adipose Tissue Oxidative Stress in Obesity

Perivascular adipose tissue (PVAT) adheres to most systemic blood vessels in the body. Healthy PVAT exerts anticontractile effects on blood vessels and further protects against cardiovascular and metabolic diseases. Healthy PVAT regulates vascular homeostasis via secreting an array of adipokine, hormones, and growth factors. Normally, homeostatic reactive oxygen species (ROS) in PVAT act as secondary messengers in various signalling pathways and contribute to vascular tone regulation. Excessive ROS are eliminated by the antioxidant defence system in PVAT. Oxidative stress occurs when the production of ROS exceeds the endogenous antioxidant defence, leading to a redox imbalance. Oxidative stress is a pivotal pathophysiological process in cardiovascular and metabolic complications. In obesity, PVAT becomes dysfunctional and exerts detrimental effects on the blood vessels. Therefore, redox balance in PVAT emerges as a potential pathophysiological mechanism underlying obesity-induced cardiovascular diseases. In this review, we summarise new findings describing different ROS, the major sources of ROS and antioxidant defence in PVAT, as well as potential pharmacological intervention of PVAT oxidative stress in obesity.

Obesity, Cardiovascular and Neurodegenerative Diseases: Potential Common Mechanisms

The worldwide increase in the incidence of obesity and cardiovascular and neurodegenerative diseases, e.g. Alzheimer's disease, is related to many factors, including an unhealthy lifestyle and aging populations. However, the interconnection between these diseases is not entirely clear, and it is unknown whether common mechanisms underlie these conditions. Moreover, there are currently no fully effective therapies for obesity and neurodegeneration. While there has been extensive research in preclinical models addressing these issues, the experimental findings have not been translated to the clinic. Another challenge relates to the time of onset of individual diseases, which may not be easily identified, since there are no specific indicators or biomarkers that define disease onset. Hence knowing when to commence preventive treatment is unclear. This is especially pertinent in neurodegenerative diseases, where the onset of the disease may be subtle and occur decades before the signs and symptoms manifest. In metabolic and cardiovascular disorders, the risk may occur in-utero, in line with the concept of fetal programming. This review provides a brief overview of the link between obesity, cardiovascular and neurodegenerative diseases and discusses potential common mechanisms including the role of the gut microbiome.

Perivascular Adipose Tissue and Vascular Smooth Muscle Tone: Friends or Foes?

Perivascular adipose tissue (PVAT) is a specialized type of adipose tissue that surrounds most mammalian blood vessels. PVAT is a metabolically active, endocrine organ capable of regulating blood vessel tone, endothelium function, vascular smooth muscle cell growth and proliferation, and contributing critically to cardiovascular disease onset and progression. In the context of vascular tone regulation, under physiological conditions, PVAT exerts a potent anticontractile effect by releasing a plethora of vasoactive substances, including NO, H₂S, H₂O₂, prostacyclin, palmitic acid methyl ester, angiotensin 1-7, adiponectin, leptin, and omentin. However, under certain pathophysiological conditions, PVAT exerts pro-contractile effects by decreasing the production of anticontractile and increasing that of pro-contractile factors, including superoxide anion, angiotensin II, catecholamines, prostaglandins, chemerin, resistin, and visfatin. The present review discusses the regulatory effect of PVAT on vascular tone and the factors involved. In this scenario, dissecting the precise role of PVAT is a prerequisite to the development of PVAT-targeted therapies.

Food Restriction Augmented Alpha1-Adrenergic Mediated Contraction in Mesenteric Arteries

Food restriction (FR) enhances sensitivity to cardiopulmonary reflexes and α1-adrenoreceptors in females in the presence of hypotension. However, the effect of FR on cardiopulmonary and vascular function in males is not well-understood. This study examines the effects of FR on cardiopulmonary, isolated arterial function, and potential underlying mechanisms. Male Sprague-Dawley (SD) rats were randomly divided into 3 groups and monitored for 5 weeks: (1) control (n = 30), (2) 20% food reduction (FR20, n = 30), and (3) 40% food reduction (FR40, n = 30). Non-invasive blood pressure was measured twice a week. Pulmonary arterial pressure (PAP) was measured using isolated/perfused lungs. The isolated vascular reactivity was assessed using double-wire myographs. FR rats exhibited a lower mean arterial pressure and heart rate; however, only the FR40 group exhibited statistically significant differences. We observed that FR enhanced sensitivity (EC₅₀) to vasoconstriction induced by the α1-adrenoreceptor phenylephrine (PhE) but not to serotonin, U46619, or high K⁺ in the mesenteric arteries. PhE-mediated vasoconstriction in the mesenteric arteries was eliminated in the presence of the eNOS inhibitor (L-NAME). In addition, incubation with NOX2/4 inhibitors (apocynin, GKT137831, and VAS2870) and the reactive oxygen species (ROS) scavenger inhibitor (Tiron) eliminated the differences in PhE-mediated vasoconstriction, but the cyclooxygenase inhibitor (indomethacin) in the mesenteric arteries did not. Augmentation of α1-adrenergic-mediated contraction via the inhibition of the eNOS-NO pathway increased the activation of ROS through NOX2/4 in response to FR. Reduced eNOS-NO signaling may be a pathophysiological counterbalance to prevent hypovolemic shock in response to FR.

Particulate Matter and Its Components Induce Alteration on the T-Cell Response: A Population Biomarker Study

Compared with the T-cell potential of particulate matter (PM) in animal studies, comprehensive evaluation on the impairments of T-cell response and exposure-response from PM and its components in human population is limited. There were 768 participants in this study. We measured environmental PM and its polycyclic aromatic hydrocarbons (PAHs) and metals and urinary metabolite levels of PAHs and metals among population. T lymphocyte and its subpopulation (CD4⁺ T cells and CD8⁺ T cells) and the expressions of T-bet, GATA3, RORγt, and FoxP3 were measured. We explored the exposure-response of PM compositions by principal component analysis and mode of action by mediation analysis. There was a significant decreasing trend for T lymphocytes and the levels of T-bet and GATA3 with increased PM levels. Generally, there was a negative correlation between PM, urinary 1-hydroxypyrene, urinary metals, and the levels of T-bet and GATA3 expression. Additionally, CD4⁺ T lymphocytes were found to mediate the associations of PM_2.5 with T-bet expression. PM and its bound PAHs and metals could induce immune impairments by altering the T lymphocytes and genes of T-bet and GATA3.

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.

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.

Supportive treatment of vascular dysfunction in pediatric subjects with obesity: the OBELIX study

INTRODUCTION

Overweight or obese children develop abnormal endothelial cell dysfunction and arterial intima-media thickening with increased vasomotor tone and inflammation. Curcumin, resveratrol, zinc, magnesium, selenium, and vitamin D have shown beneficial effects on endothelial function. We test, among overweight and obese pediatric subjects, the effects on the endothelium of a combination of curcumin, resveratrol, zinc, magnesium, selenium, and vitamin D.

METHODS

Forty-eight subjects (6-17 years) were randomized into two groups (placebo vs treatment) attended three visits at 0, 3, and 6 months (±15 days). Endothelial function was assessed by means of a post-occlusive release hyperemic (PORH) test for estimation of delta flow (DF) and hyperemic AUC index, and a heat provocation test (HPT) to measure DF HPT (DF_HPT).

RESULTS

Significant DF difference was noted at 6 months in both groups (p < 0.001). Overall time trend was significantly different between baseline, 3 months, and 6 months both in placebo (p < 0.05) and treatment (p < 0.001) groups and their comparison (p < 0.001). No differences were noted in hyperemic AUC index (3 and 6 months), whilst there were significant differences in time trends of rreatment (p < 0.001) and placebo (p < 0.05) groups and their comparison (p < 0.001). DF_HPT difference between groups was significant at 3 and 6 months (p < 0.05). The overall time trend was significant exclusively in Treatment group between 3 and 6 months (p < 0.05). Correlation with anthropometrics was found for DF and body mass index (r = 0.677 6 months, p < 0.05), as well as for hyperemic AUC index and males (r = 0.348, p < 0.05), while DF_HPT showed no correlation.

CONCLUSION

Curcumin, resveratrol, zinc, magnesium, selenium, and vitamin D appear to be promising in enhancing endothelial function by improvement of both DF in the PORH test and DF in the HPT, lowering the risk of developing cardiovascular diseases in overweight and obese pediatric subjects.

Physiological Changes and Pathological Pain Associated with Sedentary Lifestyle-Induced Body Systems Fat Accumulation and Their Modulation by Physical Exercise

A sedentary lifestyle is associated with overweight/obesity, which involves excessive fat body accumulation, triggering structural and functional changes in tissues, organs, and body systems. Research shows that this fat accumulation is responsible for several comorbidities, including cardiovascular, gastrointestinal, and metabolic dysfunctions, as well as pathological pain behaviors. These health concerns are related to the crosstalk between adipose tissue and body systems, leading to pathophysiological changes to the latter. To deal with these health issues, it has been suggested that physical exercise may reverse part of these obesity-related pathologies by modulating the cross talk between the adipose tissue and body systems. In this context, this review was carried out to provide knowledge about (i) the structural and functional changes in tissues, organs, and body systems from accumulation of fat in obesity, emphasizing the crosstalk between fat and body tissues; (ii) the crosstalk between fat and body tissues triggering pain; and (iii) the effects of physical exercise on body tissues and organs in obese and non-obese subjects, and their impact on pathological pain. This information may help one to better understand this crosstalk and the factors involved, and it could be useful in designing more specific training interventions (according to the nature of the comorbidity).

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 physiologic and physiopathologic roles of perivascular adipose tissue and its interactions with blood vessels and the renin-angiotensin system

The perivascular adipose tissue (PVAT) refers to an ectopic local deposit of connective tissue that anatomically surrounds most of the blood vessels. While it was initially known only as a structural support for vasculature, the landmark findings of Soltis and Cassis (1991), first demonstrating that PVAT reduces the contractions of norepinephrine in the isolated rat aorta, brought the potential vascular role of PVAT into the limelight. This seminal work implied the potential ability of PVAT to influence vascular responsiveness. Several vasoactive/vasocrine substances influencing vascular homeostasis were successively shown to be released from PVAT that include both adipocyte-derived relaxing and contracting factors. The PVAT is currently recognized as a metabolically active endocrine organ and is eventually considered as the 'protagonist' in vascular homeostasis. It plays prominent defending and opposing roles in vascular function, while the actual vascular influences of PVAT vary with an increase in adiposity. Recent studies have presented compelling evidence implicating the pivotal role of PVAT in the local activation of the renin-angiotensin system (RAS), which substantially impacts vascular physiology and physiopathology. Current findings have advanced our understanding of the role of PVAT in favorably or adversely modulating the vascular function through differential RAS activation. Given that adipocytes also produce major RAS components locally to influence vascular function, this review provides a scientific basis to distinctly understand the key role of PVAT in regulating the autocrine and paracrine functions of vascular RAS components and its potential as an emerging therapeutic target for mitigating cardiovascular complications.

The Sick Adipose Tissue: New Insights Into Defective Signaling and Crosstalk With the Myocardium

Adipose tissue (AT) biology is linked to cardiovascular health since obesity is associated with cardiovascular disease (CVD) and positively correlated with excessive visceral fat accumulation. AT signaling to myocardial cells through soluble factors known as adipokines, cardiokines, branched-chain amino acids and small molecules like microRNAs, undoubtedly influence myocardial cells and AT function via the endocrine-paracrine mechanisms of action. Unfortunately, abnormal total and visceral adiposity can alter this harmonious signaling network, resulting in tissue hypoxia and monocyte/macrophage adipose infiltration occurring alongside expanded intra-abdominal and epicardial fat depots seen in the human obese phenotype. These processes promote an abnormal adipocyte proteomic reprogramming, whereby these cells become a source of abnormal signals, affecting vascular and myocardial tissues, leading to meta-inflammation, atrial fibrillation, coronary artery disease, heart hypertrophy, heart failure and myocardial infarction. This review first discusses the pathophysiology and consequences of adipose tissue expansion, particularly their association with meta-inflammation and microbiota dysbiosis. We also explore the precise mechanisms involved in metabolic reprogramming in AT that represent plausible causative factors for CVD. Finally, we clarify how lifestyle changes could promote improvement in myocardiocyte function in the context of changes in AT proteomics and a better gut microbiome profile to develop effective, non-pharmacologic approaches to CVD.

Regional Heterogeneity of Perivascular Adipose Tissue: Morphology, Origin, and Secretome

Perivascular adipose tissue (PVAT) is a unique fat depot with local and systemic impacts. PVATs are anatomically, developmentally, and functionally different from classical adipose tissues and they are also different from each other. PVAT adipocytes originate from different progenitors and precursors. They can produce and secrete a wide range of autocrine and paracrine factors, many of which are vasoactive modulators. In the context of obesity-associated low-grade inflammation, these phenotypic and functional differences become more evident. In this review, we focus on the recent findings of PVAT’s heterogeneity by comparing commonly studied adipose tissues around the thoracic aorta (tPVAT), abdominal aorta (aPVAT), and mesenteric artery (mPVAT). Distinct origins and developmental trajectory of PVAT adipocyte potentially contribute to regional heterogeneity. Regional differences also exist in ways how PVAT communicates with its neighboring vasculature by producing specific adipokines, vascular tone regulators, and extracellular vesicles in a given microenvironment. These insights may inspire new therapeutic strategies targeting the PVAT.

Contribution of PGC-1α to Obesity- and Caloric Restriction-Related Physiological Changes in White Adipose Tissue

Peroxisome proliferator-activated receptor γ coactivator-1 α (PGC-1α) regulates mitochondrial DNA replication and mitochondrial gene expression by interacting with several transcription factors. White adipose tissue (WAT) mainly comprises adipocytes that store triglycerides as an energy resource and secrete adipokines. The characteristics of WAT vary in response to systemic and chronic metabolic alterations, including obesity or caloric restriction. Despite a small amount of mitochondria in white adipocytes, accumulated evidence suggests that mitochondria are strongly related to adipocyte-specific functions, such as adipogenesis and lipogenesis, as well as oxidative metabolism for energy supply. Therefore, PGC-1α is expected to play an important role in WAT. In this review, we provide an overview of the involvement of mitochondria and PGC-1α with obesity- and caloric restriction-related physiological changes in adipocytes and WAT.

Immune spleen cells attenuate the inflammatory profile of the mesenteric perivascular adipose tissue in obese mice

The perivascular adipose tissue (PVAT) differs from other fat depots and exerts a paracrine action on the vasculature. The spleen has an important role in the immune response, and it was observed to have either a protective role or a contribution to obesity-related diseases. However, the relation between spleen and PVAT is elusive in obesity. We investigated the role of spleen in the inflammatory profile of the mesenteric PVAT (mPVAT) from mice fed a high-fat diet (HFD) for 16 weeks. Male C57Bl/6 mice were sham-operated or splenectomized (SPX) and fed a HFD for 16 weeks. mPVAT morphology was evaluated by hematoxylin and eosin staining, infiltrated immune cells were evaluated by flow cytometry, inflammatory cytokines were evaluated by ELISA and the splenic cell chemotaxis mediated by mPVAT was evaluated using a transwell assay. In SPX mice, HFD induced adipocyte hypertrophy and increased immune cell infiltration and proinflammatory cytokine levels in mPVAT. However, none of these effects were observed in mPVAT from sham-operated mice. Spleen from HFD fed mice presented reduced total leukocytes and increased inflammatory markers when compared to the spleen from control mice. Chemotaxis of spleen cells mediated by mPVAT of HFD fed mice was reduced in relation to standard diet fed mice. The spleen protects mPVAT against the effects of 16-week HFD. This information was missing, and it is important because PVAT is different from other fat depots and data cannot be extrapolated from any type of adipose tissue to PVAT.

Male and female high-fat diet-fed Dahl SS rats are largely protected from vascular dysfunctions: PVAT contributions reveal sex differences

Vascular dysfunctions are observed in the arteries from hypertensive subjects. The establishment of the Dahl salt-sensitive (SS) male and female rat models to develop a reproducible hypertension with high-fat (HF) diet feeding from weaning allows addressing the question of whether HF diet-associated hypertension results in vascular dysfunction similar to that of essential hypertension in both sexes. We hypothesized that dysfunction of three distinct vascular layers, i.e., endothelial, smooth muscle, and perivascular adipose tissue (PVAT), would be present in the aorta from HF diet-fed versus control diet-fed male and female rats. Dahl SS rats were fed a control (10% kcal of fat) or HF (60%) diet from weaning for 24 wk. Male and female Dahl SS rats became equally hypertensive when placed on a HF diet. For male and female rats, the thoracic aorta exhibited medial hypertrophy in HF diet-induced hypertension versus control, but neither displayed a hyperresponsive contraction to the α-adrenergic agonist phenylephrine nor an endothelial cell dysfunction as measured by acetylcholine-induced relaxation. A beneficial PVAT function, support of stress relaxation, was reduced in the male versus female rats fed a HF diet. PVAT in the aorta of males but not in females retained the anticontractile activity. We conclude that this HF model does not display the same vascular dysfunctions observed in essential hypertension. Moreover, both male and female show significantly different vascular dysfunctions in this HF feeding model.NEW & NOTEWORTHY Although the aorta exhibits medial hypertrophy in response to HF diet-induced hypertension, it did not exhibit hyperresponsive contraction to an α-adrenergic agonist nor endothelial cell dysfunction; this was true for both sexes. Unlike other hypertension models, PVAT around aorta from (male) rats on the HF diet retained significant anticontractile activity. PVAT around aorta of the male on a HF diet was modestly more fibrotic and lost the ability to assist in arterial stress relaxation.

Roles of Perivascular Adipose Tissue in Hypertension and Atherosclerosis

Significance: Perivascular adipose tissue (PVAT), which is present surrounding most blood vessels, from the aorta to the microvasculature of the dermis, is mainly composed of fat cells, fibroblasts, stem cells, mast cells, and nerve cells. Although the PVAT is objectively present, its physiological and pathological significance has long been ignored. Recent Advances: PVAT was considered as a supporting component of blood vessels and a protective cushion to the vessel wall from the neighboring tissues during relaxation and contraction. Nonetheless, further extensive research found that PVAT actively regulates blood vessel tone through PVAT-derived vasoactive factors, including both relaxing and contracting factors. In addition, PVAT contributes to atherosclerosis through paracrine secretion of a large number of bioactive factors such as adipokines and cytokines. Thereby, PVAT regulates the functions of blood vessels through various mechanisms operating directly on PVAT or on the underlying vessel layers, including vascular smooth muscle cells (VSMCs) and endothelial cells (ECs). Critical Issues: PVAT is a unique adipose tissue that plays an essential role in maintaining the vascular structure and regulating vascular function and homeostasis. This review focuses on recent updates on the various PVAT roles in hypertension and atherosclerosis. Future Directions: Future studies should further investigate the actual contribution of alterations in PVAT metabolism to the overall systemic outcomes of cardiovascular disease, which remains largely unknown. In addition, the messengers and underlying mechanisms responsible for the crosstalk between PVAT and ECs and VSMCs in the vascular wall should be systematically addressed, as well as the contributions of PVAT aging to vascular dysfunction.

Vascular Dysfunction in Diabetes and Obesity: Focus on TRP Channels

Transient receptor potential (TRP) superfamily consists of a diverse group of non-selective cation channels that has a wide tissue distribution and is involved in many physiological processes including sensory perception, secretion of hormones, vasoconstriction/vasorelaxation, and cell cycle modulation. In the blood vessels, TRP channels are present in endothelial cells, vascular smooth muscle cells, perivascular adipose tissue (PVAT) and perivascular sensory nerves, and these channels have been implicated in the regulation of vascular tone, vascular cell proliferation, vascular wall permeability and angiogenesis. Additionally, dysfunction of TRP channels is associated with cardiometabolic diseases, such as diabetes and obesity. Unfortunately, the prevalence of diabetes and obesity is rising worldwide, becoming an important public health problems. These conditions have been associated, highlighting that obesity is a risk factor for type 2 diabetes. As well, both cardiometabolic diseases have been linked to a common disorder, vascular dysfunction. In this review, we briefly consider general aspects of TRP channels, and we focus the attention on TRPC (canonical or classical), TRPV (vanilloid), TRPM (melastatin), and TRPML (mucolipin), which were shown to be involved in vascular alterations of diabetes and obesity or are potentially linked to vascular dysfunction. Therefore, elucidation of the functional and molecular mechanisms underlying the role of TRP channels in vascular dysfunction in diabetes and obesity is important for the prevention of vascular complications and end-organ damage, providing a further therapeutic target in the treatment of these metabolic diseases.

Restoring Perivascular Adipose Tissue Function in Obesity Using Exercise

Purpose

Perivascular adipose tissue (PVAT) exerts an anti-contractile effect which is vital in regulating vascular tone. This effect is mediated via sympathetic nervous stimulation of PVAT by a mechanism which involves noradrenaline uptake through organic cation transporter 3 (OCT3) and β₃-adrenoceptor-mediated adiponectin release. In obesity, autonomic dysfunction occurs, which may result in a loss of PVAT function and subsequent vascular disease. Accordingly, we have investigated abnormalities in obese PVAT, and the potential for exercise in restoring function.

Methods

Vascular contractility to electrical field stimulation (EFS) was assessed ex vivo in the presence of pharmacological tools in ±PVAT vessels from obese and exercised obese mice. Immunohistochemistry was used to detect changes in expression of β₃-adrenoceptors, OCT3 and tumour necrosis factor-α (TNFα) in PVAT.

Results

High fat feeding induced hypertension, hyperglycaemia, and hyperinsulinaemia, which was reversed using exercise, independent of weight loss. Obesity induced a loss of the PVAT anti-contractile effect, which could not be restored via β₃-adrenoceptor activation. Moreover, adiponectin no longer exerts vasodilation. Additionally, exercise reversed PVAT dysfunction in obesity by reducing inflammation of PVAT and increasing β₃-adrenoceptor and OCT3 expression, which were downregulated in obesity. Furthermore, the vasodilator effects of adiponectin were restored.

Conclusion

Loss of neutrally mediated PVAT anti-contractile function in obesity will contribute to the development of hypertension and type II diabetes. Exercise training will restore function and treat the vascular complications of obesity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10557-020-07136-0.

Interleukin-33 rescues perivascular adipose tissue anticontractile function in obesity

Perivascular adipose tissue (PVAT) depots are metabolically active and play a major vasodilator role in healthy lean individuals. In obesity, they become inflamed and eosinophil-depleted and the anticontractile function is lost with the development of diabetes and hypertension. Moreover, eosinophil-deficient ΔdblGATA-1 mice lack PVAT anticontractile function and exhibit hypertension. Here, we have investigated the effects of inducing eosinophilia on PVAT function in health and obesity. Control, obese, and ΔdblGATA-1 mice were administered intraperitoneal injections of interleukin-33 (IL-33) for 5 days. Conscious restrained blood pressure was measured, and blood was collected for glucose and plasma measurements. Wire myography was used to assess the contractility of mesenteric resistance arteries. IL-33 injections induced a hypereosinophilic phenotype. Obese animals had significant elevations in blood pressure, blood glucose, and plasma insulin, which were normalized with IL-33. Blood glucose and insulin levels were also lowered in lean treated mice. In arteries from control mice, PVAT exerted an anticontractile effect on the vessels, which was enhanced with IL-33 treatment. In obese mice, loss of PVAT anticontractile function was rescued by IL-33. Exogenous application of IL-33 to isolated arteries induced a rapidly decaying endothelium-dependent vasodilation. The therapeutic effects were not seen in IL-33-treated ΔdblGATA-1 mice, thereby confirming that the eosinophil is crucial. In conclusion, IL-33 treatment restored PVAT anticontractile function in obesity and reversed development of hypertension, hyperglycemia, and hyperinsulinemia. These data suggest that targeting eosinophil numbers in PVAT offers a novel approach to the treatment of hypertension and type 2 diabetes in obesity.NEW & NOTEWORTHY In this study, we have shown that administering IL-33 to obese mice will restore PVAT anticontractile function, and this is accompanied by normalized blood pressure, blood glucose, and plasma insulin. Moreover, the PVAT effect is enhanced in control mice given IL-33. IL-33 induced a hypereosinophilic phenotype in our mice, and the effects of IL-33 on PVAT function, blood pressure, and blood glucose are absent in eosinophil-deficient mice, suggesting that the effects of IL-33 are mediated via eosinophils.

Lifestyle interventions for the prevention and treatment of hypertension

Hypertension affects approximately one third of the world's adult population and is a major cause of premature death despite considerable advances in pharmacological treatments. Growing evidence supports the use of lifestyle interventions for the prevention and adjuvant treatment of hypertension. In this Review, we provide a summary of the epidemiological research supporting the preventive and antihypertensive effects of major lifestyle interventions (regular physical exercise, body weight management and healthy dietary patterns), as well as other less traditional recommendations such as stress management and the promotion of adequate sleep patterns coupled with circadian entrainment. We also discuss the physiological mechanisms underlying the beneficial effects of these lifestyle interventions on hypertension, which include not only the prevention of traditional risk factors (such as obesity and insulin resistance) and improvements in vascular health through an improved redox and inflammatory status, but also reduced sympathetic overactivation and non-traditional mechanisms such as increased secretion of myokines.

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 as a Target for Antioxidant Therapy for Cardiovascular Complications

Perivascular adipose tissue (PVAT) is the connective tissue surrounding most of the systemic blood vessels. PVAT is now recognized as an important endocrine tissue that maintains vascular homeostasis. Healthy PVAT has anticontractile, anti-inflammatory, and antioxidative roles. Vascular oxidative stress is an important pathophysiological event in cardiometabolic complications of obesity, type 2 diabetes, and hypertension. Accumulating data from both humans and experimental animal models suggests that PVAT dysfunction is potentially linked to cardiovascular diseases, and associated with augmented vascular inflammation, oxidative stress, and arterial remodeling. Reactive oxygen species produced from PVAT can be originated from mitochondria, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, and uncoupled endothelial nitric oxide synthase. PVAT can also sense vascular paracrine signals and response by secreting vasoactive adipokines. Therefore, PVAT may constitute a novel therapeutic target for the prevention and treatment of cardiovascular diseases. In this review, we summarize recent findings on PVAT functions, ROS production, and oxidative stress in different pathophysiological settings and discuss the potential antioxidant therapies for cardiovascular diseases by targeting PVAT.

Greater Periaortic Fat Volume at Midlife Is Associated with Slower Gait Speed Later in Life in Women: The SWAN Cardiovascular Fat Ancillary Study

BACKGROUND

Higher perivascular adipose tissue (PVAT) contributes to adverse physiologic alterations in the vascular wall, and thus could potentially limit normal physical function later in life. We hypothesize that higher PVAT volume at midlife is prospectively associated with slower gait speed later in life, independent of overall adiposity and other risk factors.

METHODS

Participants from the Study of Women's Health Across the Nation (SWAN) cardiovascular fat ancillary study were included. PVAT volume around the descending aorta was quantified using existing computed tomography scans at midlife, while gait speed was measured after an average of 10.4 ± 0.7 years.

RESULTS

Two hundred and seventy-six women (aged 51.3 ± 2.8 years at PVAT assessment) were included. Mean gait speed was 0.96 ± 0.21 m/s. Adjusting for study site, race, education level, menopausal status, and length of descending aorta at PVAT assessment, and age, body mass index, difficulty paying for basics, overall health and smoking status at gait speed assessment, a higher midlife PVAT volume was associated with a slower gait speed later in life (p = .03). With further adjustment for presence of any comorbid conditions by the time of gait speed assessment, the association persisted; every 1SD increase in log-PVAT was associated with 3.3% slower gait speed (95% confidence interval: 0.3-6.3%; p = .03).

CONCLUSION

Greater PVAT in midlife women may contribute to poorer physical function in older age supporting a potential role of midlife PVAT in multiple domains of healthy aging. Additional research is needed to fully elucidate the physiologic changes associated with PVAT that may underlie the observed associations.

Perivascular adipose tissue in age-related vascular disease

Perivascular adipose tissue (PVAT), a crucial regulator of vascular homeostasis, is actively involved in vascular dysfunction during aging. PVAT releases various adipocytokines, chemokines and growth factors. In an endocrine and paracrine manner PVAT-derived factors regulate vascular signalling and inflammation modulating functions of adjacent layers of the vasculature. Pathophysiological conditions such as obesity, type 2 diabetes, vascular injury and aging can cause PVAT dysfunction, leading to vascular endothelial and smooth muscle cell dysfunctions. We and others have suggested that PVAT is involved in the inflammatory response of the vascular wall in diet induced obesity animal models leading to vascular dysfunction due to disappearance of the physiological anticontractile effect. Previous studies confirm a crucial role for pinpointed PVAT inflammation in promoting vascular oxidative stress and inflammation in aging, enhancing the risk for development of cardiovascular disease. In this review, we discuss several studies and mechanisms linking PVAT to age-related vascular diseases. An overview of the suggested roles played by PVAT in different disorders associated with the vasculature such as endothelial dysfunction, neointimal formation, aneurysm, vascular contractility and stiffness will be performed. PVAT may be considered a potential target for therapeutic intervention in age-related vascular disease.

PVAT: an important guardian of the cardiovascular system

Perivascular adipose tissue (PVAT) had long been considered to serve only structural, vessel-supporting purposes, but today PVAT is recognized to be an endocrine organ with important physiological and pathological effects. The expansion of PVAT in vascular homeostasis and vascular disease has attracted much interest. PVAT has been shown to release a wide spectrum of molecules, such as PVAT-derived relaxing factors (PVATRFs) and PVAT-derived contracting factors (PVATCFs). PVAT dysfunction may lead to obesity, atherosclerosis, and other cardiovascular diseases. This review describes recent advances in our understanding of PVAT's important effects on the cardiovascular system.

Endothelial Dysfunction in Obesity-Induced Inflammation: Molecular Mechanisms and Clinical Implications

Obesity is characterized by the excessive deposition of fat that may interfere with the normal metabolic process of the body. It is a chronic condition associated with various metabolic syndromes, whose prevalence is grossly increasing, and affects both children and adults. Accumulation of excessive macronutrients on the adipose tissues promotes the secretion and release of inflammatory mediators, including interleukin-6 (IL-6), interleukin 1β, tumor necrotic factor-α (TNF-α), leptin, and stimulation of monocyte chemoattractant protein-1 (MCP-1), which subsequently reduce the production of adiponectin thereby initiating a proinflammatory state. During obesity, adipose tissue synthesizes and releases a large number of hormones and cytokines that alter the metabolic processes, with a profound influence on endothelial dysfunction, a situation associated with the formation of atherosclerotic plaque. Endothelial cells respond to inflammation and stimulation of MCP-1, which is described as the activation of adhesion molecules leading to proliferation and transmigration of leukocytes, which facilitates their increase in atherogenic and thromboembolic potentials. Endothelial dysfunction forms the cornerstone of this discussion, as it has been considered as the initiator in the progression of cardiovascular diseases in obesity. Overexpression of proinflammatory cytokines with subsequent reduction of anti-inflammatory markers in obesity, is considered to be the link between obesity-induced inflammation and endothelial dysfunction. Inhibition of inflammatory mechanisms and management and control of obesity can assist in reducing the risks associated with cardiovascular complications.

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.

Anti-obesity effects of enzyme-treated celery extract in mice fed with high-fat diet

The present study demonstrated the anti-obesity effects of enzyme-treated celery extract (ECE) in mice on high-fat diet (HFD). In vitro studies showed that ECE has anti-adipogenic properties by inhibiting lipid accumulations in adipose cells. In vivo studies indicated that the administration of ECE markedly prevented HFD-induced body weight gain, food efficiency ratio, and epididymal fat and liver weights. ECE reduced lipid parameters, cardiac risk factor, and atherogenic index in obese mice. ECE prevented a diabetes state by improving adipokines levels, reducing glucose levels, and preventing insulin resistance. Moreover, ECE prevented HFD-induced liver damage by preventing hepatic steatosis and upregulation of liver antioxidant enzymes. The mechanism of ECE was partially investigated to involve the activation of 5' adenosine monophosphate-activated protein kinase and hence the downregulation of CCAAT/enhancer binding protein α and peroxisome proliferator-activated receptor γ by ECE. Our results suggest that ECE could be used as functional food materials for the prevention of obesity. PRACTICAL APPLICATIONS: Apium graveolens is a popular plant with nutritive and medicinal benefits. It contains bioactive compounds such as apiin, apigenin, and luteolin. However, these compounds are rendered insoluble due to their interaction with polysaccharides in the cell wall thus making them less bioavailable. Hydrolyzing them could increase the yield of bioactive compounds in celery. This pilot study demonstrates that pectinase-treated celery extract has anti-obesity effects. The results of this research demonstrate the use of enzymes in improving the biological activities of plant extracts and suggest the use of enzyme-assisted extraction techniques in the industrial production of health functional food from celery.

Mechanistic Links Between Obesity, Diabetes, and Blood Pressure: Role of Perivascular Adipose Tissue

Obesity is increasingly prevalent and is associated with substantial cardiovascular risk. Adipose tissue distribution and morphology play a key role in determining the degree of adverse effects, and a key factor in the disease process appears to be the inflammatory cell population in adipose tissue. Healthy adipose tissue secretes a number of vasoactive adipokines and anti-inflammatory cytokines, and changes to this secretory profile will contribute to pathogenesis in obesity. In this review, we discuss the links between adipokine dysregulation and the development of hypertension and diabetes and explore the potential for manipulating adipose tissue morphology and its immune cell population to improve cardiovascular health in obesity.

Differential metabolic and inflammatory responses to intermittent hypoxia in substrains of lean and obese C57BL/6 mice

AIMS

This study was to investigate the degree of susceptibility to intermittent hypoxia (IH), a hallmark of obstructive sleep apnea (OSA), between the two mice inbred lines C57BL/6N (6N) and C57BL/6J (6J).

MATERIALS AND METHODS

Four-week old male mice of 6N and 6J substrains (n = 8) were randomized to standard diet (SD) group or high fat (HF) diet group. At the age of 13-week, all two groups of mice were subjected to either air or IH (IH30; thirty hypoxic events per hour) for one week.

KEY FINDINGS

All mice fed with HF diet exhibited obesity with more body weight and fat mass (percentage to body weight) gain. IH reduced serum LDL, HDL and total cholesterol levels in lean 6J mice. In obese mice, IH lowered obesity-induced serum total cholesterol level in 6J substrain but raised further in 6N substrain. Furthermore, IH caused elevation of serum FFA and MDA levels, and pro-inflammatory cytokines MCP-1 and IL-6 levels in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) of lean 6J but not lean 6N mice. There was reduced number of adipocytes and elevation of macrophages in SAT and VAT of HF-induced obese mice of both substrains. IH led to increased number of adipocytes and macrophages in SAT of lean 6J mice.

SIGNIFICANCE

The genetic difference between 6N and 6J mice may have direct impact on metabolic and inflammatory responses after IH. Therefore, attention must be given for the selection of C57BL mice substrains in the experimental IH-exposed mouse model.

Perivascular Adipose Tissue Contributes to the Modulation of Vascular Tone in vivo

BACKGROUND

Perivascular adipose tissue (PVAT) reduces vascular tone in isolated arteries in vitro, however there are no studies of PVAT effects on vascular tone in vivo. In vitro adipocyte β3-adrenoceptors play a role in PVAT function via secretion of the vasodilator adiponectin.

OBJECTIVE

We have investigated the effects of PVAT on vessel diameter in vivo, and the contributions of β3-adrenoceptors and adiponectin.

METHOD

In anaesthetised rats, sections of the intact mesenteric bed were visualised and the diameter of arteries was recorded. Arteries were stimulated with electrical field stimulation (EFS), noradrenaline (NA), arginine-vasopressin (AVP), and acetylcholine (Ach).

RESULTS

We report that in vivo, stimulation of PVAT with EFS, NA, and AVP evokes a local anti-constrictive effect on the artery, whilst PVAT exerts a pro-contractile effect on arteries subjected to Ach. The anti-constrictive effect of PVAT stimulated with EFS and NA was significantly reduced using β3-adrenoceptor inhibition, and activation of β3-adrenoceptors potentiated the anti-constrictive effect of vessels stimulated with EFS, NA, and AVP. The β3-adrenoceptor agonist had no effect on mesenteric arteries with PVAT removed. A blocking peptide for adiponectin receptor 1 polyclonal antibody reduced the PVAT anti-constrictive effect in arteries stimulated with EFS and NA, indicating that adiponectin may be the anti-constrictive factor released upon β3-adrenoceptor activation.

CONCLUSIONS

These results clearly demonstrate that PVAT plays a paracrine role in regulating local vascular tone in vivo, and therefore may contribute to the modulation of blood pressure. This effect is mediated via adipocyte β3-adrenoceptors, which may trigger release of the vasodilator adiponectin.

Resistin Mediates Sex-Dependent Effects of Perivascular Adipose Tissue on Vascular Function in the Shrsp

Premenopausal women are relatively protected from developing hypertension compared to men. Perivascular adipose tissue (PVAT) has been shown to mediate vasoactive effects; however, a sex-dependent difference in PVAT function in the setting of hypertension has not yet been explored. We investigated the effect of PVAT on resistance vessel biology in male and female 16 week old stroke prone spontaneously hypertensive rats (SHRSP). This preclinical model of hypertension exhibits a sex-dependent difference in the development of hypertension similar to humans. Wire myography was used to assess vascular function in third-order mesenteric arteries. K_ATP channel-mediated vasorelaxation by cromakalim was significantly impaired in vessels from SHRSP males + PVAT relative to females (maximum relaxation: male + PVAT 46.9 ± 3.9% vs. female + PVAT 97.3 ± 2.7%). A cross-over study assessing the function of male PVAT on female vessels confirmed the reduced vasorelaxation response to cromakalim associated with male PVAT (maximum relaxation: female + PVAT_female90.6 ± 1.4% vs. female + PVAT_male65.8 ± 3.5%). In order to explore the sex-dependent differences in PVAT at a molecular level, an adipokine array and subsequent western blot validation identified resistin expression to be increased approximately 2-fold in PVAT from male SHRSP vessels. Further wire myography experiments showed that pre-incubation with resistin (40 ng/ml) significantly impaired the ability of female + PVAT vessels to relax in response to cromakalim (maximum relaxation: female + PVAT 97.3 ± 0.9% vs. female + PVAT + resistin_[40ng/ml]36.8 ± 2.3%). These findings indicate a novel role for resistin in mediating sex-dependent vascular function in hypertension through a K_ATP channel-mediated mechanism.

Developmental and functional characteristics of the thoracic aorta perivascular adipocyte

Thoracic aorta perivascular adipose tissue (T-PVAT) has critical roles in regulating vascular homeostasis. However, the developmental characteristics and cellular lineage of adipocyte in the T-PVAT remain unclear. We show that T-PVAT contains three long strip-shaped fat depots, anterior T-PVAT (A-T-PVAT), left lateral T-PVAT (LL-T-PVAT), and right lateral T-PVAT (RL-T-PVAT). A-T-PVAT displays a distinct transcriptional profile and developmental origin compared to the two lateral T-PVATs (L-T-PVAT). Lineage tracing studies indicate that A-T-PVAT adipocytes are primarily derived from SM22α+ progenitors, whereas L-T-PVAT contains both SM22α+ and Myf5+ cells. We also show that L-T-PVAT contains more UCP1+ brown adipocytes than A-T-PVAT, and L-T-PVAT exerts a greater relaxing effect on aorta than A-T-PVAT. Angiotensin II-infused hypertensive mice display greater macrophage infiltration into A-T-PVAT than L-T-PVAT. These combined results indicate that L-T-PVAT has a distinct development from A-T-PVAT with different cellular lineage, and suggest that L-T-PVAT and A-T-PVAT have different physiological and pathological functions.

New Therapeutic Implications of Endothelial Nitric Oxide Synthase (eNOS) Function/Dysfunction in Cardiovascular Disease

The Global Burden of Disease Study identified cardiovascular risk factors as leading causes of global deaths and life years lost. Endothelial dysfunction represents a pathomechanism that is associated with most of these risk factors and stressors, and represents an early (subclinical) marker/predictor of atherosclerosis. Oxidative stress is a trigger of endothelial dysfunction and it is a hall-mark of cardiovascular diseases and of the risk factors/stressors that are responsible for their initiation. Endothelial function is largely based on endothelial nitric oxide synthase (eNOS) function and activity. Likewise, oxidative stress can lead to the loss of eNOS activity or even “uncoupling” of the enzyme by adverse regulation of well-defined “redox switches” in eNOS itself or up-/down-stream signaling molecules. Of note, not only eNOS function and activity in the endothelium are essential for vascular integrity and homeostasis, but also eNOS in perivascular adipose tissue plays an important role for these processes. Accordingly, eNOS protein represents an attractive therapeutic target that, so far, was not pharmacologically exploited. With our present work, we want to provide an overview on recent advances and future therapeutic strategies that could be used to target eNOS activity and function in cardiovascular (and other) diseases, including life style changes and epigenetic modulations. We highlight the redox-regulatory mechanisms in eNOS function and up- and down-stream signaling pathways (e.g., tetrahydrobiopterin metabolism and soluble guanylyl cyclase/cGMP pathway) and their potential pharmacological exploitation.

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.

Perivascular Adipose Tissue-Derived PDGF-D Contributes to Aortic Aneurysm Formation During Obesity

Obesity increases the risk of vascular diseases, including aortic aneurysm (AA). Perivascular adipose tissue (PVAT) surrounding arteries are altered during obesity. However, the underlying mechanism of adipose tissue, especially PVAT, in the pathogenesis of AA is still unclear. Here we showed that angiotensin II (AngII) infusion increases the incidence of AA in leptin-deficient obese mice (ob/ob) and high-fat diet-induced obese mice with adventitial inflammation. Furthermore, transcriptome analysis revealed that platelet-derived growth factor-D (PDGF-D) was highly expressed in the PVAT of ob/ob mice. Therefore, we hypothesized that PDGF-D mediates adventitial inflammation, which provides a direct link between PVAT dysfunction and AA formation in AngII-infused obese mice. We found that PDGF-D promotes the proliferation, migration, and inflammatory factors expression in cultured adventitial fibroblasts. In addition, the inhibition of PDGF-D function significantly reduced the incidence of AA in AngII-infused obese mice. More importantly, adipocyte-specific PDGF-D transgenic mice are more susceptible to AA formation after AngII infusion accompanied by exaggerated adventitial inflammatory and fibrotic responses. Collectively, our findings reveal a notable role of PDGF-D in the AA formation during obesity, and modulation of this cytokine might be an exploitable treatment strategy for the condition.

New insights into the role of adipose tissue in thrombosis

Central obesity is independently associated with an elevated risk of cardiovascular disease, particularly thrombotic complications. Increasing data supports a link between excess body weight and the risk to suffer acute myocardial infarction, stent thrombosis after percutaneous interventions, ischemic stroke and vein thrombosis. Experimental and in vitro data have provided insights as to the mechanisms currently presumed to increase the thrombotic risk in obese subjects. Obesity is characterized by a chronic low grade inflammation and systemic oxidative stress that eventually damage the endothelium losing its antithrombotic properties. Obesity also stimulates the expression of leptin and attenuates adiponectin release, a protective adipokine. Although the contribution of adipokines to thrombosis has been questioned, recent work has suggested that they enhance platelet activation and, although to a lesser extent, induce the coagulation cascade through tissue factor (TF) expression. Increased body weight also impairs platelet sensitivity to insulin signaling and enhances the production of bioactive isoprostanes further promoting platelet reactivity. Finally, obese subjects have shown elevated circulating levels of von Willebrand factor, TF, factor VII and VIII, and fibrinogen, favoring a mild-to-moderate hypercoagulable state, and, on the other hand, increased secretion of plasminogen activator inhibitor (PAI)-1 and thrombin activatable fibrinolysis inhibitor (TAFI) contributing to impair the fibrinolytic system. In the present review, we provide an overview of the impact of excess body weight on thrombosis. We will focus on the link between dysfunctional adipose tissue and endothelial damage, platelet reactivity, enhanced coagulation and impaired fibrinolysis; mechanisms currently recognized to increase arterial thrombotic risk in obese subjects.

Thermogenic capacity of human periaortic adipose tissue is transformed by body weight

The anatomical location of adipose tissue might have direct implications for its functionality and risk of cardiovascular disease. Adipose tissue surrounding blood vessels may be thermogenically more active in specific areas of the body, releasing substances that regulate vascular metabolism. In humans, the phenotypic characteristics of adipose tissue surrounding the aorta and the cardiovascular disease risk that it might entail remain largely unknown. Here, we compared thermogenesis-related molecular features of human periaortic adipose tissue samples with those of subcutaneous adipose tissue, obtained by sternotomy from 42 patients undergoing cardiovascular surgery. To determine the expression of genes related to energy expenditure and the levels of some adipokines, histological examinations, quantitative PCR, and protein expression measurements in adipocyte precursor cells were performed. Periaortic adipocytes were smaller than those from subcutaneous tissue. Moreover, weight gain induced periaortic adipocyte hypertrophy (r = -0.91, p<0.01). Compared to subcutaneous tissue, adiponectin, FABP4, IL-4 and IL-6 was decreased in periaortic adipocytes, whereas FGF21, UCP-1, PGC-1a, CITED1, Omentin and TFAM (Mitochondrial protein) increased. Upon analyzing patients’ clinical conditions, it emerged that the levels of PGC-1a both in male (r = -0.48 p<0.04) and female (r = -0.61, p<0.05) and TFAM in male (r = -0.72, p<0.0008) and female (r = -0.86, p<0.002) decreased significantly with progressive weight gain. However, no differences were observed in patients with diabetes mellitus 2 or Hyperlipidemia. Adipocytes surrounding the ascending aorta present markers of major thermogenic activity than those in subcutaneous tissue. Nevertheless, this characteristic might change, due to unfavorable metabolic conditions such as obesity, which is a risk factor for cardiovascular disease.

Role of Sympathetic Nerves and Adipocyte Catecholamine Uptake in the Vasorelaxant Function of Perivascular Adipose Tissue

OBJECTIVE

Healthy perivascular adipose tissue (PVAT) exerts an anticontractile effect on resistance arteries which is vital in regulating arterial tone. Activation of β₃-adrenoceptors by sympathetic nerve-derived NA (noradrenaline) may be implicated in this effect and may stimulate the release of the vasodilator adiponectin from adipocytes. Understanding the mechanisms responsible is vital for determining how PVAT may modify vascular resistance in vivo.

APPROACH AND RESULTS

Electrical field stimulation profiles of healthy C57BL/6J mouse mesenteric resistance arteries were characterized using wire myography. During electrical field stimulation, PVAT elicits a reproducible anticontractile effect, which is endothelium independent. To demonstrate the release of an anticontractile factor, the solution surrounding stimulated exogenous PVAT was transferred to a PVAT-denuded vessel. Post-transfer contractility was significantly reduced confirming that stimulated PVAT releases a transferable anticontractile factor. Sympathetic denervation of PVAT using tetrodotoxin or 6-hydroxydopamine completely abolished the anticontractile effect. β₃-adrenoceptor antagonist SR59203A reduced the anticontractile effect, although the PVAT remained overall anticontractile. When the antagonist was used in combination with an OCT3 (organic cation transporter 3) inhibitor, corticosterone, the anticontractile effect was completely abolished. Application of an adiponectin receptor-1 blocking peptide significantly reduced the anticontractile effect in +PVAT arteries. When used in combination with the β₃-adrenoceptor antagonist, there was no further reduction. In adiponectin knockout mice, the anticontractile effect is absent.

CONCLUSIONS

The roles of PVAT are 2-fold. First, sympathetic stimulation in PVAT triggers the release of adiponectin via β₃-adrenoceptor activation. Second, PVAT acts as a reservoir for NA, preventing it from reaching the vessel and causing contraction.