Perivascular Adipose Tissue Inflammation Research Articles

Perivascular adipose tissue-derived extracellular vesicle miR-221-3p mediates vascular remodeling.

Adipose tissue-secreted extracellular vesicles (EVs) containing microRNAs (miRNAs) convey intercellular message signaling. The biogenesis of EV-miRNAs from perivascular adipose tissue (PVAT) and their roles in intercellular communication in response to obesity-associated inflammation have not yet been fully explored. By feeding mice a high-fat diet for 16 wk, we established obesity-associated, chronic low-grade inflammation in PVAT, characterized as hypertrophy of perivascular adipocytes, decreased adipogenesis, and proinflammatory macrophage infiltration. We show that PVAT-derived EVs and their encapsulated miRNAs can be taken up into vascular smooth muscle cells (VSMCs) in vivo and in vitro. miR-221-3p is one of the highly enriched miRNAs in obese PVAT and PVAT-derived EVs. Transfer and direct overexpression of miR-221-3p dramatically enhances VSMC proliferation and migration. Peroxisome proliferator-activated receptor γ coactivator 1α is identified as a miR-221-3p target in VSMC phenotypic modulation. Obese mice secrete abundant miRNA-containing EVs, evoking inflammatory responses in PVAT and vascular phenotypic switching in abdominal aorta of lean mice. Local delivery of miR-221-3p mimic in femoral artery causes vascular dysfunction by suppressing the contractile genes in the arterial wall. Our findings provide an EV-miR-221-3p-mediated mechanism by which PVAT triggers an early-stage vascular remodeling in the context of obesity-associated inflammation.-Li, X., Ballantyne, L. L., Yu, Y., Funk, C. D. Perivascular adipose tissue-derived extracellular vesicle miR-221-3p mediates vascular remodeling.

Abstract 218: Pathophysiological Significance of Browning of Perivascular Adipose Tissue in the Development of Atherosclerosis

Background: Perivascular adipose tissue (PVAT) possibly plays a pivotal role in the development of atherosclerosis through its direct local action to the vessels. However, its physiological and molecular mechanisms are less understood. Visceral and subcutaneous white adipose tissues exert a brown adipose tissue-like phenotype under specific conditions such as cold exposure, i.e. browning. We here investigated the pathophysiological role of browning of PVAT against the development of atherosclerosis after endovascular injury. Methods and Results: Endovascular injury was generated by wire insertion into the femoral artery of C57BL/6 female mice. Transcriptome analysis revealed robust upregulation of brown adipose tissue markers such as Ucp1 , Elovl3 , Cox8b and Cidea in injured arteries. Notably, administration of an atheroprotective agent, 17-beta estradiol, significantly inhibited these changes; Ucp1 was the most down-regulated gene by 17-beta estradiol administration in the entire gene set (log2-fold change = -6.58, false discovery rate = 0.003). Consistently, the upregulation of browning markers after endovascular injury and these inhibitions by 17-beta estradiol were confirmed in PVAT by quantitative real-time PCR, western blot and immunohistochemical staining. The present study also demonstrated that vascular injury promotes macrophage infiltration in PVAT accompanied with upregulation of inflammatory cytokine production. Furthermore, we confirmed spatiotemporal synchronicity between browning and inflammation in PVAT by immunohistochemical staining. Conclusions: We observed that endovascular injury elicits browning in PVAT accompanied with exacerbated inflammation, and that atheroprotective 17-beta estradiol strongly inhibits this phenomenon. These findings may provide novel insights into pathogenesis of the atherosclerosis.

Does Inflammation In Perivascular Adipose Tissue Affect The Adjacent Arterial Wall?

Background and Aims: Macrophages play an important role in atherosclerosis development. The aim of this project was to explain whether pro-inflammatory macrophage polarization in perivascular adipose tissue (PVAT) could be associated with inflammatory changes in the arterial wall.

SIRT3-MEDIATED MACROPHAGE PYRUVATE DEHYDROGENASE ACTIVITY IMPROVES PERIVASCULAR ADIPOSE TISSUE REMODELING IN HYPERTENSIVE MICE

Objective: Infiltrated macrophages are a dominant population in the perivascular adipose tissue (PVAT) microenvironment and actively promote PVAT remodeling in hypertensive mice. However, the molecular mechanism underlying the role of macrophages in initiating metabolic inflammation remains uncertain. Here, we investigate whether Situin-3(SIRT3) is determinant in macrophage activation. Design and method: 10-week-old male WT, SIRT3 KO, and NLRP3 KO mice were infused with Angiotension II (Ang II, 1000ng/kg/min) or normal saline (NS) for 7 days. The morphological and functional changes of thoracic aorta and PVAT were determined by histological analysis and immunofluorescence staining. In vitro studies were performed on bone marrow-derived macrophages (BMDMs) and brown adipocytes isolated from WT or SIRT3 KO mice. Results: We report that Ang II accelerates PVAT inflammation and fibrosis in SIRT3-deficient mice. This effect is associated with attenuating browning markers and lipid droplet-associated protein expression. Immunofluorescence analysis confirmed that there is an increase in NLRP3 inflammasome and secretion of interleukin-1β (IL-1β). In vitro studies indicate that BMDMs from SIRT3 KO mice induce interleukin-IL-1β production by shifting metabolic phenotype from oxidative phosphorylation towards glycolysis. Mechanically, SIRT3 deacetylates and activates pyruvate dehydrogenase E1 alpha (PDHE1a) at lysine 83, loss of SIRT3 lead to decreased PDH activity, and accumulation of pyruvate and lactate metabolites. The PDHK inhibitor dichloroacetate (DCA) suppresses both pro-IL-1β maturation and caspase-1 activation in macrophages in response to Ang II. The blockade of IL-1β from macrophage into brown adipocytes restores expression of brown adipocyte specific markers. Coincidentally, NLRP3 KO mice exhibited a reduction in infiltrated macrophages in PVAT, while partially rescuing brown adipocytes mitochondrial function and collagen accumulation. Conclusions: Taken together, these findings reveal that SIRT3-mediated activity of PDHE1a inhibits macrophage activation. Pharmacological targeting of glycolysis metabolism may therefore represent an effective approach.

The role of immune cells in the development of adipose tissue dysfunction in cardiovascular diseases

Adipose tissue dysfunction characterized by a loss of homeostatic functions It is observed in patients with obesity, insulin resistance and diabetes. In case of violation of the physiological properties in adipose tissue, an increased production of cytokines and chemokines occurs with the infiltration of tissue by immune cells. In turn, immune cells also produce cytokines, metalloproteinases, reactive oxygen species and chemokines, which are involved in tissue remodeling, cellular signal transduction and immunity regulation. The presence of inflammatory cells in adipose tissue affects organs and tissues. So in the blood vessels, inflammation of perivascular adipose tissue leads to vascular remodeling, superoxide production, endothelial dysfunction with loss of the bioavailability of nitric oxide, contributing to the development of various vascular diseases. In adipose tissue dysfunction, adipokines are also produced, such as leptin, resistin, and visfatin. These substances contribute to metabolic dysfunction, alter systemic homeostasis, sympathetic outflow, glucose regulation, and insulin sensitivity. Thus, the study of the mechanisms of interaction between immune cells and adipose tissue is promising and may be an important therapeutic target.

Coronary Artery Spasm and Perivascular Adipose Tissue Inflammation: Insights From Translational Imaging Research.

Perivascular adipose tissue, which constitutes perivascular components along with the adventitial vasa vasorum, plays an important role as a source of various inflammatory mediators in cardiovascular disease. Inflammatory changes in the coronary adventitia are thought to be involved in the pathogenesis of coronary artery spasm and vasospastic angina. Recent advances in translational research using non-invasive imaging modalities, including 18F-fluorodeoxyglucose PET and cardiac CT, have enabled us to visualise perivascular inflammation in the pathogenesis of coronary artery spasm. These modality approaches appear to be clinically useful as a non-invasive tool for examining the presence and severity of vasospastic angina.

Metabolic Stress‐Induced Renal Endothelial Dysfunction

The burden of metabolic syndrome (MetS) is increasing globally. MetS has been shown to increase the risk for developing cardiovascular diseases, diabetes and mortality. As such, our group previously reported that perivascular adipose tissue inflammation was associated with cardiac autonomic, aortic contractile and aortic endothelial dysfunction. MetS has been also associated with high levels of kidney disease markers including glomerular filtration rate, proteinuria, and microalbuminuria. In this study, we investigated the impact of MetS on the renal endothelial function in rats fed with high caloric diet for 4, 8, and 12 weeks. Following the planned duration of high caloric intake, kidneys were isolated and perfused with physiological solution containing L‐NAME (NOS inhibitor) and diclofenac (cyclooxygenase inhibitor), and preconstricted with phenylephrine. Endothelial function was assessed as the reduction in vasodilation in response carbachol (CCh). In control rats, nitric oxide (NO) and prostaglandins were found to be the major mediators of the endothelial vasodilatory effect. On the other hand, gradual alteration in renal endothelial function was detected as the duration of the HC feeding was increased. Compared to control values, kidneys obtained from rats with HC intake showed significant increases in CCh‐induced vasodilation. Moreover, prostaglandin vasodilatory function was abolished at 8 weeks followed by loss of NO activity at 12 weeks. Additionally, the residual CCh‐induced relaxation following L‐NAME and diclofenac infusion was no longer concentration dependent, suggesting an upregulation of a poorly controlled compensatory mechanism. Studies were extended to investigate further renal changes in this rat model. HC feeding led to increased glomerular oxidative stress, mesangial expansion and glomerulosclerosis. Together, these results suggest that increasing caloric intake initiate an early progressive renal damage that could be linked to adipose inflammation.Support or Funding InformationResearch support: AUB‐FM grant #320148.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Emerging Roles of Sympathetic Nerves and Inflammation in Perivascular Adipose Tissue

Perivascular adipose tissue (PVAT) is no longer recognised as simply a structural support for the vasculature, and we now know that PVAT releases vasoactive factors which modulate vascular function. Since the discovery of this function in 1991, PVAT research is rapidly growing and the importance of PVAT function in disease is becoming increasingly clear. Obesity is associated with a plethora of vascular conditions; therefore, the study of adipocytes and their effects on the vasculature is vital. PVAT contains an adrenergic system including nerves, adrenoceptors and transporters. In obesity, the autonomic nervous system is dysfunctional; therefore, sympathetic innervation of PVAT may be the key mechanistic link between increased adiposity and vascular disease. In addition, not all obese people develop vascular disease, but a common feature amongst those that do appears to be the inflammatory cell population in PVAT. This review will discuss what is known about sympathetic innervation of PVAT, and the links between nerve activation and inflammation in obesity. In addition, we will examine the therapeutic potential of exercise in sympathetic stimulation of adipose tissue.

Brown Adipocyte-Specific PPARγ (Peroxisome Proliferator-Activated Receptor γ) Deletion Impairs Perivascular Adipose Tissue Development and Enhances Atherosclerosis in Mice.

Objective- Perivascular adipose tissue (PVAT) contributes to vascular homeostasis by producing paracrine factors. Previously, we reported that selective deletion of PPARγ (peroxisome proliferator-activated receptor γ) in vascular smooth muscle cells resulted in concurrent loss of PVAT and enhanced atherosclerosis in mice. To address the causal relationship between loss of PVAT and atherosclerosis, we used BA-PPARγ-KO (brown adipocyte-specific PPARγ knockout) mice. Approach and Results- Deletion of PPARγ in brown adipocytes did not affect PPARγ in white adipocytes or vascular smooth muscle cells or PPARα and PPARδ expression in brown adipocytes. However, development of PVAT and interscapular brown adipose tissue was remarkably impaired, associated with reduced expression of genes encoding lipogenic enzymes in the BA-PPARγ-KO mice. Thermogenesis in brown adipose tissue was significantly impaired with reduced expression of thermogenesis genes in brown adipose tissue and compensatory increase in subcutaneous and gonadal white adipose tissues. Remarkably, basal expression of inflammatory genes and macrophage infiltration in PVAT and brown adipose tissue were significantly increased in the BA-PPARγ-KO mice. BA-PPARγ-KO mice were crossbred with ApoE KO (apolipoprotein E knockout) mice to investigate the development of atherosclerosis. Flow cytometry analysis confirmed increased systemic and PVAT inflammation. Consequently, atherosclerotic lesions were significantly increased in mice with impaired PVAT development, thus indicating that the lack of normal PVAT is sufficient to drive increased atherosclerosis. Conclusions- PPARγ is required for functional PVAT development. PPARγ deficiency in PVAT, while still expressed in vascular smooth muscle cell, enhances atherosclerosis and results in vascular and systemic inflammation, providing new insights on the specific roles of PVAT in atherosclerosis and cardiovascular disease at large.

Regional differences of fat depot attenuation using non-contrast, contrast-enhanced, and delayed-enhanced cardiac CT

Regional fat density assessed by computed tomography (CT) has been suggested as a marker of perivascular adipose tissue inflammation. Dual energy CT (DECT) allows improved tissue characterization compared to conventional CT. To explore whether DECT might aid regional fat density discrimination. We included patients who had completed a non-enhanced cardiac CT scan, CT coronary angiography (CTCA), and a delayed enhancement CT. Attenuation levels (Hounsfield units [HU]) were assessed at the epicardial, paracardial, visceral, and subcutaneous fat. The number of coronary segments with disease (SIS) was calculated. A total of 36 patients were included in the analysis. Twenty-six (72%) patients had evidence of obstructive disease at CCTA and 25 (69%) patients had evidence of previous myocardial infarction. At non-contrast CT, we did not identify significant attenuation differences between epicardial, paracardial, subcutaneous, and visceral fat depots (-110.8 ± 9 HU, vs. -113.7 ± 9 HU, vs. -114.7 ± 8 HU, vs. -113.8 ± 11 HU, P = 0.36). Significant attenuation differences were detected between fat depots at mid and low energy levels, both at CTCA and delayed-enhancement scans ( P < 0.05 for all). Epicardial fat showed the least negative attenuation, irrespective of the acquisition mode; epicardial fat evaluated at 40 keV was related to the SIS (r = 0.37, P = 0.03). In this study, regional fat depots amenable to examination during thoracic CT scans have distinctive regional attenuation values. Furthermore, such differences were better displayed using contrast-enhanced monochromatic imaging at low energy levels.

MitoNEET in Perivascular Adipose Tissue Prevents Arterial Stiffness in Aging Mice

Arterial stiffness is an inevitable consequence of the aging process and is considered an early stage in the development of cardiovascular diseases. The perivascular adipose tissue (PVAT) is a distinct functional integral layer of the vasculature actively involved in blood pressure regulation and atherosclerosis development via PVAT-derived paracrine/autocrine factors. However, there is little knowledge regarding the relationship between PVAT and arterial stiffness. Using unique mice lacking PVAT, high-fat diet-induced obesity, and in mice overexpressing brown adipocyte selective mitoNEET, we investigated the relationship between PVAT and arterial stiffness in mice. We found that lack of PVAT enhanced arterial stiffness in aging mice. High-fat diet feeding of aging C57BL/6J wild-type mice significantly induced hypertrophic PVAT and enhanced arterial stiffness. Furthermore, the expression of mitoNEET, a mitochondrial membrane protein related to energy expenditure, was significantly increased by pioglitazone treatment, while reduced in the hypertrophic PVAT induced by high-fat diet. Overexpression of mitoNEET in PVAT reduced the expression of inflammatory genes and was associated with lower pulse wave velocity in aging mice. These data indicate that local PVAT homeostasis especially inflammation in PVAT is associated with arterial stiffness development. Pioglitazone-induced mitoNEET in PVAT prevents PVAT inflammation and is negatively associated with arterial stiffness. These findings provide new experimental insight into the roles of pioglitazone on PVAT in arterial stiffness and indicate that PVAT might be a target to treat or prevent cardiovascular disease.

Saxagliptin Prevents Increased Coronary Vascular Stiffness in Aortic-Banded Mini Swine.

Increased peripheral conduit artery stiffness has been shown in patients with heart failure (HF) with preserved ejection fraction. However, it is unknown whether this phenomenon extends to the coronary vasculature. HF with preserved ejection fraction may be driven, in part, by coronary inflammation, and inhibition of the enzyme DPP-4 (dipeptidyl-peptidase 4) reduces inflammation and oxidative stress. The purpose of this study was to determine the effect of saxagliptin-a DPP-4 inhibitor-on coronary stiffness in aortic-banded mini swine. We hypothesized saxagliptin would prevent increased coronary artery stiffness in a translational swine model with cardiac features of HF with preserved ejection fraction by inhibiting perivascular adipose tissue inflammation. Yucatan mini swine were divided into 3 groups: control, aortic-banded untreated HF, and aortic-banded saxagliptin-treated HF. Ex vivo mechanical testing was performed on the left circumflex and right coronary arteries, and advanced glycation end product, NF-κB (nuclear factor-κB), and nitrotyrosine levels were measured. An increase in the coronary elastic modulus of HF animals was associated with increased vascular advanced glycation end products, NF-κB, and nitrotyrosine levels compared with control and prevented by saxagliptin treatment. Aortas from healthy mice were treated with media from swine perivascular adipose tissue culture to assess its role on vascular stiffening. Conditioned media from HF and saxagliptin-treated HF animals increased mouse aortic stiffness; however, only perivascular adipose tissue from the HF group showed increased advanced glycation end products and NF-κB levels. In conclusion, our data show increased coronary conduit vascular stiffness was prevented by saxagliptin and associated with decreased advanced glycation end products, NF-κB, and nitrotyrosine levels in a swine model with potential relevance to HF with preserved ejection fraction.

High Fat Diet Attenuates the Anticontractile Activity of Aortic PVAT via a Mechanism Involving AMPK and Reduced Adiponectin Secretion.

Background and aim: Perivascular adipose tissue (PVAT) positively regulates vascular function through production of factors such as adiponectin but this effect is attenuated in obesity. The enzyme AMP-activated protein kinase (AMPK) is present in PVAT and is implicated in mediating the vascular effects of adiponectin. In this study, we investigated the effect of an obesogenic high fat diet (HFD) on aortic PVAT and whether any changes involved AMPK.Methods: Wild type Sv129 (WT) and AMPKα1 knockout (KO) mice aged 8 weeks were fed normal diet (ND) or HFD (42% kcal fat) for 12 weeks. Adiponectin production by PVAT was assessed by ELISA and AMPK expression studied using immunoblotting. Macrophages in PVAT were identified using immunohistochemistry and markers of M1 and M2 macrophage subtypes evaluated using real time-qPCR. Vascular responses were measured in endothelium-denuded aortic rings with or without attached PVAT. Carotid wire injury was performed and PVAT inflammation studied 7 days later.Key results: Aortic PVAT from KO and WT mice was morphologically indistinct but KO PVAT had more infiltrating macrophages. HFD caused an increased infiltration of macrophages in WT mice with increased expression of the M1 macrophage markers Nos2 and Il1b and the M2 marker Chil3. In WT mice, HFD reduced the anticontractile effect of PVAT as well as reducing adiponectin secretion and AMPK phosphorylation. PVAT from KO mice on ND had significantly reduced adiponectin secretion and no anticontractile effect and feeding HFD did not alter this. Wire injury induced macrophage infiltration of PVAT but did not cause further infiltration in KO mice.Conclusions: High-fat diet causes an inflammatory infiltrate, reduced AMPK phosphorylation and attenuates the anticontractile effect of murine aortic PVAT. Mice lacking AMPKα1 phenocopy many of the changes in wild-type aortic PVAT after HFD, suggesting that AMPK may protect the vessel against deleterious changes in response to HFD.

Cellular mechanisms underlying obesity-induced arterial stiffness.

Obesity is an emerging pandemic driven by consumption of a diet rich in fat and highly refined carbohydrates (a Western diet) and a sedentary lifestyle in both children and adults. There is mounting evidence that arterial stiffness in obesity is an independent and strong predictor of cardiovascular disease (CVD), cognitive functional decline, and chronic kidney disease. Cardiovascular stiffness is a precursor to atherosclerosis, systolic hypertension, cardiac diastolic dysfunction, and impairment of coronary and cerebral flow. Moreover, premenopausal women lose the CVD protection normally afforded to them in the setting of obesity, insulin resistance, and diabetes, and this loss of CVD protection is inextricably linked to an increased propensity for arterial stiffness. Stiffness of endothelial and vascular smooth muscle cells, extracellular matrix remodeling, perivascular adipose tissue inflammation, and immune cell dysfunction contribute to the development of arterial stiffness in obesity. Enhanced endothelial cortical stiffness decreases endothelial generation of nitric oxide, and increased oxidative stress promotes destruction of nitric oxide. Our research over the past 5 years has underscored an important role of increased aldosterone and vascular mineralocorticoid receptor activation in driving development of cardiovascular stiffness, especially in females consuming a Western diet. In this review the cellular mechanisms of obesity-associated arterial stiffness are highlighted.

Perivascular adipose tissue as an endocrine organ: the role of statins.

Adipose tissue (AT), aside from being an energy storage site, functions as a source of cytokines, adipokines and other vasoactive molecules. Dysfunctional AT contributes to the development of cardiovascular disease by shifting to a pro-oxidant, pro-inflammatory phenotype. Perivascular AT (PVAT) is of particular importance to the development of vascular disease, due to its close proximity to the vascular wall. Molecules released from PVAT can exert both pro- and anti-contractile effects, the balance of which plays a role in controlling vascular tone. Recent evidence supports the existence of reciprocal, two-way interactions between PVAT and the vascular wall. Statins, with their pivotal role in cardiovascular disease prevention, have been shown to exert lipid-lowering independent, pleiotropic effects on the vascular wall, some of which may be mediated by modulatory effects on PVAT inflammation and secretome. These effects of statins provide a paradigm for the development of new therapeutic agents aimed at modulating PVAT function, as a novel treatment strategy against cardiovascular disease.

Association of Coronary Perivascular Adipose Tissue Inflammation and Drug-Eluting Stent-Induced Coronary Hyperconstricting Responses in Pigs: 18F-Fluorodeoxyglucose Positron Emission Tomography Imaging Study.

Although coronary perivascular adipose tissue (PVAT) may play important roles as a source of inflammation, the association of coronary PVAT inflammation and coronary hyperconstricting responses remains to be examined. We addressed this important issue in a porcine model of coronary hyperconstricting responses after drug-eluting stent implantation with 18F-fluorodeoxyglucose (18F-FDG) positron emission tomographic imaging. An everolimus-eluting stent (EES) was randomly implanted in pigs into the left anterior descending or the left circumflex coronary artery while nonstented coronary artery was used as a control. After 1 month, coronary vasoconstricting responses to intracoronary serotonin (10 and 100 μg/kg) were examined by coronary angiography in vivo, followed by in vivo and ex vivo 18F-FDG positron emission tomographic/computed tomographic imaging. Coronary vasoconstricting responses to serotonin were significantly enhanced at the EES edges compared with the control site (P<0.01; n=40). Notably, in vivo and ex vivo 18F-FDG positron emission tomographic/computed tomographic imaging and autoradiography showed enhanced 18F-FDG uptake and its accumulation in PVAT at the EES edges compared with the control site, respectively (both P<0.05). Furthermore, histological and reverse transcription polymerase chain reaction analysis showed that inflammatory changes of coronary PVAT were significantly enhanced at the EES edges compared with the control site (all P<0.01). Importantly, Rho-kinase expressions (ROCK1/ROCK2) and Rho-kinase activity (phosphorylated myosin phosphatase target subunit-1) at the EES edges were significantly enhanced compared with the control site. These results indicate for the first time that inflammatory changes of coronary PVAT are associated with drug-eluting stent-induced coronary hyperconstricting responses in pigs in vivo and that 18F-FDG positron emission tomographic imaging is useful for assessment of coronary PVAT inflammation.

The role of infiltrating immune cells in dysfunctional adipose tissue.

Adipose tissue (AT) dysfunction, characterized by loss of its homeostatic functions, is a hallmark of non-communicable diseases. It is characterized by chronic low-grade inflammation and is observed in obesity, metabolic disorders such as insulin resistance and diabetes. While classically it has been identified by increased cytokine or chemokine expression, such as increased MCP-1, RANTES, IL-6, interferon (IFN) gamma or TNFα, mechanistically, immune cell infiltration is a prominent feature of the dysfunctional AT. These immune cells include M1 and M2 macrophages, effector and memory T cells, IL-10 producing FoxP3+ T regulatory cells, natural killer and NKT cells and granulocytes. Immune composition varies, depending on the stage and the type of pathology. Infiltrating immune cells not only produce cytokines but also metalloproteinases, reactive oxygen species, and chemokines that participate in tissue remodelling, cell signalling, and regulation of immunity. The presence of inflammatory cells in AT affects adjacent tissues and organs. In blood vessels, perivascular AT inflammation leads to vascular remodelling, superoxide production, endothelial dysfunction with loss of nitric oxide (NO) bioavailability, contributing to vascular disease, atherosclerosis, and plaque instability. Dysfunctional AT also releases adipokines such as leptin, resistin, and visfatin that promote metabolic dysfunction, alter systemic homeostasis, sympathetic outflow, glucose handling, and insulin sensitivity. Anti-inflammatory and protective adiponectin is reduced. AT may also serve as an important reservoir and possible site of activation in autoimmune-mediated and inflammatory diseases. Thus, reciprocal regulation between immune cell infiltration and AT dysfunction is a promising future therapeutic target.

Adiponectin improves endothelial function in mesenteric arteries of rats fed a high-fat diet: role of perivascular adipose tissue.

Adiponectin, the most abundant peptide secreted by adipocytes, is involved in the regulation of energy metabolism and vascular physiology. Here, we have investigated the effects of exogenous administration of adiponectin on metabolism, vascular reactivity and perivascular adipose tissue (PVAT) of mesenteric arteries in Wistar rats fed a high-fat diet. The effects of adiponectin on NO-dependent and independent vasorelaxation were investigated in isolated mesenteric arteries from 12-month-old male Wistar rats (W12m) fed a high-fat diet (HFD) for 4months and compared with those from age-matched rats given a control diet. Adiponectin ((96μg·day-1 ) was administered by continuous infusion with a minipump, implanted subcutaneously, for 28days. Chronic adiponectin treatment reduced body weight, total cholesterol, free fatty acids, fasting glucose and area under the curve of intraperitoneal glucose tolerance test, compared with HFD rats. It also normalized NO-dependent vasorelaxation increasing endothelial NO synthase (eNOS) phosphorylation in mesenteric arteries of HFD rats. In PVAT from aged (W12m) and HFD rats there was increased expression of chemokines and pro-inflammatory adipokines, the latter being important contributors to endothelial dysfunction. Infusion of adiponectin reduced these changes. Adiponectin normalized endothelial cell function by a mechanism that involved increased eNOS phoshorylation and decreased PVAT inflammation. Detailed characterization of the adiponectin signalling pathway in the vasculature and perivascular fat is likely to provide novel approaches to the management of atherosclerosis and metabolic disease. This article is part of a themed section on Molecular Mechanisms Regulating Perivascular Adipose Tissue - Potential Pharmacological Targets? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.20/issuetoc.

Exercise effects on perivascular adipose tissue: endocrine and paracrine determinants of vascular function.

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

Perivascular adipose tissue inflammation in vascular disease.

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