Changes In Perivascular Adipose Tissue Research Articles

Number of inflamed coronary vessels in prediction of cardiac death and MACE among patients undergoing routine CCTA: the Oxford Risk Factors And Non-Invasive Imaging (ORFAN) Study

Abstract Background Coronary inflammation can be assessed by the changes in perivascular adipose tissue on routine coronary CT angiograms (CCTA). Fat attenuation index score (FAI Score) quantifies the degree of inflammation in each epicardial coronary artery, and adjusts for age, sex, scan technical parameters, biological and anatomical factors. Coronary inflammation assessment in a single coronary artery was previously shown to be predictive of cardiac events in the CRISP-CT study. However, the impact of inflammation in multiple coronary arteries on clinical outcome remains unclear. Purpose To evaluate the prognostic value of the number of inflamed coronary arteries with high inflammation in the risk of cardiac death, and major adverse cardiac events (MACE). Methods In a nested cohort within the Oxford Risk Factors And Non-invasive imaging (ORFAN) study, consecutive patients (n=3,393) who underwent routine clinical CCTA were followed up over a median(IQR) 7.7(6.4-9.1) years for cardiac mortality, and MACE (including myocardial infarction, new onset heart failure, cardiac mortality). FAI Score was calculated for each of the 3 epicardial coronary arteries. Results The number of inflamed arteries (FAI Score >75th centile) showed an additive impact on cardiac mortality compared with no inflamed arteries (all vessels FAI Score <25th centile), with hazard ratio 29.8 (95% CI 13.9-63.9, p<0.001) for 3 inflamed arteries, HR 20.4 (95% CI 9.4-44.7, p<0.001) for 2 inflamed arteries, and HR 13.0 (95% CI 5.9-28.8, p<0.001) for 1 inflamed artery. (Panel A) Similarly, patients with multiple inflamed arteries showed progressively higher risk for MACE (HR 7.2, 8.3 and 12.6 for 1-, 2- and 3-inflamed arteries respectively compared to patients with no inflamed artery). (Panel B) Patients with no inflamed arteries showed very low event rates for cardiac mortality and MACE. In patients with no obstructive CAD (n=2,651), similar trends were observed whereby patients with 3-inflamed arteries showed highest risk for cardiac mortality (Panel C) and MACE (Panel D), with intermediate risk for those with 1 or 2 inflamed arteries. Conclusion The number of coronary arteries with high inflammation, measured by FAI Score from routine CCTA, is associated with adverse cardiovascular events and cardiac mortality in an additive dose-response manner.

Abstract 1110: The Sex-specific Role Of The Mineralocorticoid Receptor In Smooth Muscle Cells In Obesity-associated Vascular Stiffness

Introduction: Obesity is associated with increased vascular stiffness which predicts risk for heart attack, stroke and cardiovascular (CV) mortality. Obesity is more common and has a greater negative impact on CV health in women. Perivascular adipose tissue (PVAT), which contributes to maintenance of normal vascular tone, becomes dysfunctional in obesity, but its role in vascular stiffness is less well studied. Mineralocorticoid receptor (MR) is a hormone-activated transcription factor regulated by inflammation and oxidative stress in aging vascular smooth muscle cells (SMC) where it induces vascular stiffness. The role of SMC-MR in obesity-associated vascular stiffness and whether there are sex differences in the mechanism is unknown. Hypothesis: We hypothesized that sex differences in obesity-induced changes in PVAT alters aortic inflammation and oxidative stress (OS) to induce SMC MR and contribute to aortic stiffness by regulating sexually dimorphic gene programs. Methods and Results: Young male and female mice (3 months old) with MR intact or SMC-MR knocked out (SMC-MR-KO) were fed with high-fat diet (HFD) for 3 months. In both sexes, MR mRNA expression increased with obesity in MR intact mice, as did aortic stiffness (by pulse wave velocity (PWV)). SMC-MR-KO prevented the HFD-induced vascular stiffness in both sexes. In aortas from male mice only, NFkB protein were induced by obesity, independent of the MR. Obese males had increased vascular fibrosis histologically, vascular fibrosis gene (Col1, CTGF) expression and inflammation (TNFa, IL1B) in MR intact mice and is prevented in the SMC-MR-KO mice. In females, HIF1a protein and mRNA were induced by obesity, independent of SMC MR. In MR-intact females, OS gene expression (NADPH-oxidase 2-4 (Nox2, Nox4)) was increased by HFD. Human aortic SMC (HASMCs) from lean/obese male and female donors were cultured. NFkB, MR, and Col1 were increased with obesity in HASMCs from males while HIF1a, MR, Nox2 and Nox4 were increased in obese female donors compared with non-obese. Conclusions: These data support sexually dimorphic, SMC MR-dependent mechanisms for vascular stiffness associated with obesity and suggest that sex-specific therapies may be needed to prevent obesity-associated vascular stiffness.

Aldose Reductase (AR) Mediates and Perivascular Adipose Tissue (PVAT) Modulates Endothelial Dysfunction of Short-Term High-Fat Diet Feeding in Mice.

Increased adiposity of both visceral and perivascular adipose tissue (PVAT) depots is associated with an increased risk of diabetes and cardiovascular disease (CVD). Under healthy conditions, PVAT modulates vascular tone via the release of PVAT-derived relaxing factors, including adiponectin and leptin. However, when PVAT expands with high-fat diet (HFD) feeding, it appears to contribute to the development of endothelial dysfunction (ED). Yet, the mechanisms by which PVAT alters vascular health are unclear. Aldose reductase (AR) catalyzes glucose reduction in the first step of the polyol pathway and has been long implicated in diabetic complications including neuropathy, retinopathy, nephropathy, and vascular diseases. To better understand the roles of both PVAT and AR in HFD-induced ED, we studied structural and functional changes in aortic PVAT induced by short-term HFD (60% kcal fat) feeding in wild type (WT) and aldose reductase-null (AR-null) mice. Although 4 weeks of HFD feeding significantly increased body fat and PVAT mass in both WT and AR-null mice, HFD feeding induced ED in the aortas of WT mice but not of AR-null mice. Moreover, HFD feeding augmented endothelial-dependent relaxation in aortas with intact PVAT only in WT and not in AR-null mice. These data indicate that AR mediates ED associated with short-term HFD feeding and that ED appears to provoke 'compensatory changes' in PVAT induced by HFD. As these data support that the ED of HFD feeding is AR-dependent, vascular-localized AR remains a potential target of temporally selective intervention.

Fine particulate matter air pollution and aortic perivascular adipose tissue: Oxidative stress, leptin, and vascular dysfunction.

Exposure to fine particulate matter (PM2.5) air pollution increases blood pressure, induces vascular inflammation and dysfunction, and augments atherosclerosis in humans and rodents; however, the understanding of early changes that foster chronic vascular disease is incomplete. Because perivascular adipose tissue (PVAT) inflammation is implicated in chronic vascular diseases, we investigated changes in aortic PVAT following short‐term air pollution exposure. Mice were exposed to HEPA‐filtered or concentrated ambient PM2.5 (CAP) for 9 consecutive days, and the abundance of inflammatory, adipogenic, and adipokine gene mRNAs was measured by gene array and qRT‐PCR in thoracic aortic PVAT. Responses of the isolated aorta with and without PVAT to contractile (phenylephrine, PE) and relaxant agonists (acetylcholine, ACh; sodium nitroprusside, SNP) were measured. Exposure to CAP significantly increased the urinary excretion of acrolein metabolite (3HPMA) as well as the abundance of protein–acrolein adducts (a marker of oxidative stress) in PVAT and aorta, upregulated PVAT leptin mRNA expression without changing mRNA levels of several proinflammatory genes, and induced PVAT insulin resistance. In control mice, PVAT significantly depressed PE‐induced contractions—an effect that was dampened by CAP exposure. Pulmonary overexpression of extracellular dismutase (ecSOD‐Tg) prevented CAP‐induced effects on urinary 3HPMA levels, PVAT Lep mRNA, and alterations in PVAT and aortic function, reflecting a necessary role of pulmonary oxidative stress in all of these deleterious CAP‐induced changes. More research is needed to address how exactly short‐term exposure to PM2.5 perturbs PVAT and aortic function, and how these specific genes and functional changes in PVAT could lead over time to chronic inflammation, endothelial dysfunction, and atherosclerosis.

Phenotypic Changes in T Cell and Macrophage Subtypes in Perivascular Adipose Tissues Precede High-Fat Diet-Induced Hypertension.

Perivascular adipose tissue (PVAT) may connect adiposity to hypertension because of its vasoactive functions and proximity to blood vessels. We hypothesized that immune cell changes in PVATs precede the development of high fat diet (HFD)-induced hypertension. Both sexes of Dahl S rat become equally hypertensive when fed a HFD. Further, both sexes would have similar immune cell composition in PVATs with the development and progression of hypertension. Male and female Dahl S rats were fed a regular (10% calories from fat; CD) diet or a HFD (60%) from weaning. PVATs from around the thoracic aorta (APVAT) and small mesenteric vessels (MRPVAT) were harvested at 10 weeks (pre-hypertensive), 17 weeks (onset), or 24 (hypertensive) weeks on diet. RNA-sequencing in MRPVAT at 24 weeks indicated sex-differences with HFD (>CD) and diet-differences in males (>females). The top 2 out of 7 immune processes with the maximum number of differentially expressed genes (DEGs) were associated with immune effector processes and leukocyte activation. Macrophages and T cells (and their activation status), neutrophils, mast, B and NK cells were measured by flow cytometry. Sex-specific changes in the number of CD4 memory T cells (males > females) and M2-like macrophages (females > males) in PVATs occur with a HFD before hypertension developed. Sex-differences became more prominent with the development and progression of hypertension, driven by the diet (HFD > CD). These findings suggest that though the magnitudes of increased blood pressure were equivalent in both sexes, the associated phenotypic changes in the immune subsets within the PVATs were different in the male vs. the female with the development and progression of hypertension.

Adipose extracellular signal-regulated kinase 2 protected from endothelial dysfunction and the oxidative stress of perivascular adipose tissue in obese mice

Abstract Introduction Extracellular signal-regulated kinase (ERK) modulates differentiation and maturation of adipocyte and the hypertrophy and differentiation of adipocytes affected the vascular diseases in obese. Changes in characters of adipocytes could develope the oxidative stress and inflammations. Moreover, changes in perivascular adipose tissue (PVAT) could modulate vascular tonus in obesity. However, the role of adipose ERK2 in endothelial function and characters of PVAT in obese in vivo had not been clarified, yet. Purpose This study aims to elucidate the role of the adipose ERK2 in endothelial-dependent relaxation (EDR) in mice model of obesity. The role of PVAT in EDR was also assessed. Methods and results We created adipose-specific ERK2 knock out mice (AE2KO) by crossing fatty acid binding protein 4 Cre and ERK2 flox mice and fed them with normal diet (ND) or high fat/ high sucrose diet (HFHSD) for 24 weeks. AE2KO fed with HFHSD gained more weight and revealed the heterogeneity in sizes of adipocyte in subcutaneous fat (SF). Furthermore, the mRNA levels of lipoprotein lipase, hormone-sensitive lipase, and peroxisome proliferator-activated receptor γ, which was the master genes of adipocyte differentiation, were markedly down-regulated in SF. PVAT in AE2KO with HFHSD was markedly enlarged and the mRNA expression of inflammatory adipocytokines, such as IL-1β and leptin were up-regulated. Next, we assessed EDR by acetylcholine (ACh) -induced relaxation in aortic rings with or without PVAT. EDR without PVAT was modestly decreased in AE2KO with HFHSD compared with wild type mice (WT) with HFHSD. Aortic rings with PVAT increased EDR in WT with ND. PVAT modestly decreased EDR in WT with HFHSD and mostly eliminated EDR in AE2KO with HFHSD. To assess the contraction factors released from PVAT, the solutions incubated with PVAT (SIP) were transferred to the normal aortic rings. SIP from WT with HFHSD mildly increased vascular tone and SIP from AE2KO with HFHSD further increased it. Tempol, which was superoxide scavenger, restored endothelial dysfunction with PVAT and suppressed the contraction with SIP from AE2KO with HFHSD. Fluorescence intensity of dihydroethidium stain of aorta and PVAT, which indicated that aortic and adipose superoxide production were elevated in AE2KO with HFHSD, which were mostly eliminated with tempol. Conclusions Adipose ERK2 selectively modulated differentiation in SF, suppressed the aortic oxidative stress and protected from endothelial dysfunction in obese. Moreover, adipose ERK2 suppressed the hypertrophy, inflammation, and oxidative stress of PVAT in obese. The oxidative stress with the inflammation in PVAT released vasoconstriction factors, which contributed to endothelial dysfunction in obese mice. Figure 1 Funding Acknowledgement Type of funding source: None

A novel arterial redox-specific machine learning-derived radiomic signature of perivascular adipose tissue predicts cardiac mortality from routine CCTA

Abstract Background Vascular oxidative stress is involved in inflammation and atherogenesis. Vascular inflammation induces spatial changes in perivascular adipose tissue (PVAT) composition, which can be detected by radiomic analysis of coronary computed tomography angiography (CCTA) images. Purpose To explore the association of arterial oxidative stress with long-term risk of major adverse cardiovascular events (MACE). To develop a radiomic signature to identify high oxidative stress non-invasively using CCTA. Finally, to assess the ability of this signature to predict future cardiac risk. Methods Arm 1 included 272 patients undergoing cardiac surgery. Segments of internal mammary artery (IMA) were used for ex-vivo quantification of NADPH-stimulated and Vas2870 (pan-NOX inhibitor) inhibitable superoxide production by lucigenin-enhanced chemiluminescence. Eighty-two of these patients with CCTA scans available constituted Arm 2. Peri-IMA PVAT was segmented and used to extract 1,616 radiomic features, which, after filtering (40 final features), were utilised to train extreme gradient boosting, a machine learning algorithm, to predict high arterial oxidative stress. Arm 3 included a nested cohort of 308 participants (41 suffering cardiac death and 267 matched controls) from the CRISP-CT (Cardiovascular RISk Prediction using Computed Tomography) study to externally validate the redox-specific signature developed in Arm 2 for cardiac risk prediction. Results Over a median follow-up of 40 months, 18 (6.6%) MACE (cardiovascular death, non-fatal myocardial infarction, and stroke) occurred in Arm 1. High arterial NADPH-stimulated superoxide was independently associated with MACE risk (Adj. HR[95% CI]: 1.61 [1.04–2.53] per SD, p=0.03, adjusted for age, sex, diabetes, hypertension, hyperlipidemia, smoking, obesity, and plasma TNFa). Unsupervised hierarchical clustering of radiomic features from peri-IMA PVAT segments in Arm 2 identified two distinct clusters (A) that differed in NADPH stimulated (p=0.01) and Vas2870 inhibitable (p=0.04) IMA superoxide (B), supporting the hypothesis that PVAT mapping can capture changes corresponding to differential levels of underlying vascular redox state. This prompted the development of a radiomic signature specific to PVAT alterations associated with high vascular oxidative stress, which was validated in Arm 3 (AUC:0.61, p=0.026, C). The novel signature was able to stratify cardiac risk in the validation set, independently of the Fat Attenuation Index, epicardial adipose tissue volume, high-risk plaque features, and obstructive CAD (Adj. HR [95% CI]:2.56 [1.35–4.87], p=0.004, D). Conclusion Increased arterial oxidative stress predicts cardiac risk in patients with advanced atherosclerosis. We present for the first time a novel, non-invasive CCTA imaging biomarker reflecting changes in vascular redox state by radiomic phenotyping of perivascular space, which stratifies cardiac risk beyond standard and newer risk assessment methods. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): British Heart Foundation, National Institute of Health Research, Oxford Biomedical Research Centre

Pathological Conversion of Mouse Perivascular Adipose Tissue by Notch Activation.

Perivascular adipose tissue (PVAT) surrounding arteries supports healthy vascular function. During obesity, PVAT loses its vasoprotective effect. We study pathological conversion of PVAT, which involves molecular changes in protein profiles and functional changes in adipocytes. Approach and Results: C57BL6/J mice were fed a 60% high-fat diet for 12 weeks or a cardioprotective 30% calorie-restricted diet for 5 weeks. Proteomic analysis identified PVAT as a molecularly distinct adipose depot, and novel markers for thermogenic adipocytes, such as GRP75 (stress-70 protein, mitochondrial), were identified. High-fat diet increased the similarity of protein signatures in PVAT and brown adipose, suggesting activation of a conserved whitening pathway. The whitening phenotype was characterized by suppression of UCP1 (uncoupling protein 1) and increased lipid deposition, leptin, and inflammation, and specifically in PVAT, elevated Notch signaling. Conversely, PVAT from calorie-restricted mice had decreased Notch signaling and less lipid. Using the Adipoq-Cre strain, we constitutively activated Notch1 signaling in adipocytes, which phenocopied the changes in PVAT caused by a high-fat diet, even on a standard diet. Preadipocytes from mouse PVAT expressed Sca1, CD140a, Notch1, and Notch2, but not CD105, showing differences compared with preadipocytes from other depots. Inhibition of Notch signaling during differentiation of PVAT-derived preadipocytes reduced lipid deposition and adipocyte marker expression. PVAT shares features with other adipose depots, but has a unique protein signature that is regulated by dietary stress. Increased Notch signaling in PVAT is sufficient to initiate the pathological conversion of PVAT by promoting adipogenesis and lipid accumulation and may thus prime the microenvironment for vascular disease.

Age‐Related Increase in Extra‐Media Thickness is Associated with Arterial Stiffening and Carotid Blood Pressure

Older age is a primary risk factor associated with future cardiovascular disease (CVD) related events. Age‐related changes in perivascular adipose tissue (PVAT) and vascular remodeling both contribute to arterial stiffening and increased blood pressure which are established CVD risk factors. The non‐invasively measured extra‐media thickness (EMT) is a novel and composite measure, which includes PVAT, arterial adventitia, and the jugular vein that may provide translational insight for these factors contributing to age‐related arterial stiffening and higher blood pressure. However, it is unknown if aging increases EMT and is associated with arterial stiffness and blood pressure. We hypothesized that age‐related increases in EMT will be associated with higher arterial stiffness and blood pressure. Forty participants (young: 8M/12F, 23.2 ± 1.1 yrs and middle‐aged/older: 7M/13F, 60.7 ± 9.4 yrs) underwent measures of blood pressure (brachial; carotid), arterial stiffness (carotid b‐stiffness), EMT via ultrasonography and body composition with dual x‐ray absorptiometry. All measurements were taken in the supine position. Group mean differences between young and middle‐aged/older participants were analyzed with unpaired t‐tests and Pearson correlations were used to assess relations between EMT and arterial stiffness and blood pressure endpoints. Compared to younger participants, middle‐aged/older participants had higher EMT (0.80 ± 0.03 vs. 0.69 ± 0.02 mm), carotid beta stiffness (3.24 ± 0.08 vs. 2.60 ± 0.04), carotid SBP (116.5 ± 4.9 vs. 99.1 ± 2.3 mmHg), and carotid PP (44.6 ± 4.2 vs. 34.8 ± 1.5 mmHg) (all, p<0.05). Brachial SBP was not different between groups (p>0.05). Carotid beta stiffness (r= 0.410), carotid SBP (r= 0.501), and carotid PP (r= 0.5037) were all positively correlated with EMT for the entire cohort (all, p<0.05). Our findings indicate that there is an age‐related increase in EMT that is associated with both carotid arterial stiffness and pressure. These data suggest that increases in arterial stiffness and blood pressure with advancing age may be attributable, in part, to increases in EMT, which may be due to changes in PVAT and arterial adventitial remodeling. Therefore, EMT, a potential surrogate for PVAT and arterial remodeling, may provide novel insight into age‐related arterial stiffening, higher blood pressure and increased CVD risk with aging.

Luseogliflozin attenuates neointimal hyperplasia after wire injury in high-fat diet-fed mice via inhibition of perivascular adipose tissue remodeling

BackgroundExcess fat deposition could induce phenotypic changes of perivascular adipose tissue (PVAT remodeling), which may promote the progression of atherosclerosis via modulation of adipocytokine secretion. However, it remains unclear whether and how suppression of PVAT remodeling could attenuate vascular injury. In this study, we examined the effect of sodium-glucose cotransporter 2 (SGLT2) inhibitor, luseogliflozin on PVAT remodeling and neointima formation after wire injury in mice.MethodsWilt-type mice fed with low-fat diet (LFD) or high-fat diet (HFD) received oral administration of luseogliflozin (18 mg/kg/day) or vehicle. Mice underwent bilateral femoral artery wire injury followed by unilateral removal of surrounding PVAT. After 25 days, injured femoral arteries and surrounding PVAT were analyzed.ResultsIn LFD-fed lean mice, neither luseogliflozin treatment or PVAT removal attenuated the intima-to-media (I/M) ratio of injured arteries. However, in HFD-fed mice, luseogliflozin or PVAT removal reduced the I/M ratio, whereas their combination showed no additive reduction. In PVAT surrounding injured femoral arteries of HFD-fed mice, luseogliflozin treatment decreased the adipocyte sizes. Furthermore, luseogliflozin reduced accumulation of macrophages expressing platelet-derived growth factor-B (PDGF-B) and increased adiponectin gene expression. Gene expression levels of Pdgf-b in PVAT were correlated with the I/M ratio.ConclusionsOur present study suggests that luseogliflozin could attenuate neointimal hyperplasia after wire injury in HFD-fed mice partly via suppression of macrophage PDGF-B expression in PVAT. Inhibition of PVAT remodeling by luseogliflozin may be a novel therapeutic target for vascular remodeling after angioplasty.

Site-specific impairment of perivascular adipose tissue on advanced atherosclerotic plaques using multimodal nonlinear optical imaging

Perivascular adipose tissue (PVAT), as a mechanical support, has been reported to systemically regulate vascular physiology by secreting adipokines and cytokines. How PVAT spatially and locally changes as atherosclerosis progresses is not known, however. We aimed to reveal the molecular changes in PVAT in advanced atherosclerosis based on multimodal nonlinear optical (MNLO) imaging. First, using an atherogenic apolipoprotein E knockout mouse model, we precisely assessed the browning level of thoracic PVAT via a correlative analysis between the size and number of lipid droplets (LDs) of label-free MNLO images. We also biochemically demonstrated the increased level of brown fat markers in the PVAT of atherosclerosis. In the initial stage of atherosclerosis, the PVAT showed a highly activated brown fat feature due to the increased energy expenditure; however, in the advanced stage, only the PVAT in the regions of the atherosclerotic plaques, not that in the nonplaque regions, showed site-specific changes. We found that p-smad2/3 and TGF-β signaling enhanced the increase in collagen to penetrate the PVAT and the agglomeration of LDs only at the sites of atherosclerotic plaques. Moreover, atherosclerotic thoracic PVAT (tPVAT) was an increased inflammatory response. Taken together, our findings show that PVAT changes differentially from the initial stages to advanced stages of atherosclerosis and undergoes spatial impairment focused on atherosclerotic plaques. Our study may provide insight into the local control of PVAT as a therapeutic target.

JNK2 in myeloid cells impairs insulin's vasodilator effects in muscle during early obesity development through perivascular adipose tissue dysfunction.

Reduced vasodilator properties of insulin in obesity are caused by changes in perivascular adipose tissue and contribute to microvascular dysfunction in skeletal muscle. The causes of this dysfunction are unknown. The effects of a short-term Western diet on JNK2-expressing cells in perivascular adipose tissue (PVAT) on insulin-induced vasodilation and perfusion of skeletal muscle were assessed. In vivo, 2 wk of Western diet (WD) reduced whole body insulin sensitivity and insulin-stimulated muscle perfusion, determined using contrast ultrasonography during the hyperinsulinemic clamp. Ex vivo, WD triggered accumulation of PVAT in skeletal muscle and blunted its ability to facilitate insulin-induced vasodilation. Labeling of myeloid cells with green fluorescent protein identified bone marrow as a source of PVAT in muscle. To study whether JNK2-expressing inflammatory cells from bone marrow were involved, we transplanted JNK2-/- bone marrow to WT mice. Deletion of JNK2 in bone marrow rescued the vasodilator phenotype of PVAT during WD exposure. JNK2 deletion in myeloid cells prevented the WD-induced increase in F4/80 expression. Even though WD and JNK2 deletion resulted in specific changes in gene expression of PVAT; epididymal and subcutaneous adipose tissue; expression of tumor necrosis factor-α, interleukin-1β, interleukin-6, or protein inhibitor of STAT1 was not affected. In conclusion, short-term Western diet triggers infiltration of JNK2-positive myeloid cells into PVAT, resulting in PVAT dysfunction, nonclassical inflammation, and loss of insulin-induced vasodilatation in vivo and ex vivo.NEW & NOTEWORTHY We demonstrate that in the earliest phase of weight gain, changes in perivascular adipose tissue in muscle impair insulin-stimulated muscle perfusion. The hallmark of these changes is infiltration by inflammatory cells. Deletion of JNK2 from the bone marrow restores the function of perivascular adipose tissue to enhance insulin's vasodilator effects in muscle, showing that the bone marrow contributes to regulation of muscle perfusion.

Abstract 21015: Coronary Inflammation in Humans Drives Spatial Changes of Perivascular Adipose Tissue Composition Detectable by a Novel Computed Tomography-Based Technology

Background: Non-invasive detection of vascular inflammation remains an unmet goal. We hypothesized that phenotypic changes in perivascular adipose tissue (PVAT) induced by vascular inflammation can be quantified using a new computed tomography angiography (CTA) methodology. Methods: In Arm 1, human PVAT adipocytes were cultured +/- inflammatory cytokines (n=7) or co-cultured with vascular tissue (+/-Angiotensin-II, n=6) to assess the effects of vascular inflammation on PVAT differentiation. In Arm 2, AT explants (epicardial, subcutaneous and thoracic AT) from 453 cardiac surgery patients were used in histology and gene expression studies to relate the ex vivo images with in vivo CT scan information (n=105) on the biology of the explants. In Arm 3, in 267 patients undergoing diagnostic CTA, PVAT attenuation (Fat Attenuation Index (FAI) defined as the average CT attenuation of AT), was analysed around the proximal right coronary artery. In Arm 4, PVAT FAI around unstable (culprit) and stable coronary plaques was calculated in 22 CAD patients undergoing CTA. Results: In Arm 1, Angiotensin-II (A) and proinflammatory cytokines (B) prevented lipid accumulation and adipocyte differentiation in cultured PVAT. In Arm 2, adipocyte size by histology was inversely correlated with FAI in vivo (C). Both FAI of AT explants (not shown) and FAI in-vivo (n=105) were negatively associated with epicardial AT differentiation as assessed by FABP4 expression (D). In Arm 3, PVAT FAI change over distance from RCA wall was significantly different in CAD compared to no CAD patients (E). In Arm 4, PVAT FAI was significantly increased around unstable plaques (F). Conclusions: Human vessels exert paracrine effects on surrounding PVAT, affecting local intracellular lipid accumulation in preadipocytes, which can then be monitored using a CT imaging approach. This novel methodology can be implemented in clinical practice to detect unstable plaques in the human coronary vasculature.

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.

Increased mitochondrial ROS generation mediates the loss of the anti-contractile effects of perivascular adipose tissue in high-fat diet obese mice.

Obesity is associated with structural and functional changes in perivascular adipose tissue (PVAT), favouring release of reactive oxygen species (ROS), vasoconstrictor and proinflammatory factors. The cytokine TNF-α induces vascular dysfunction and is produced by PVAT. We tested the hypothesis that obesity-associated PVAT dysfunction was mediated by augmented mitochondrial ROS (mROS) generation due to increased TNF-α production in this tissue. C57Bl/6J and TNF-α receptor-deficient mice received control or high fat diet (HFD) for 18 weeks. We used pharmacological tools to determine the participation of mROS in PVAT dysfunction. Superoxide anion (O2.- ) and H2 O2 were assayed in PVAT and aortic rings were used to assess vascular function. Aortae from HFD-fed obese mice displayed increased contractions to phenylephrine and loss of PVAT anti-contractile effect. Inactivation of O2.- , dismutation of mitochondria-derived H2 O2 , uncoupling of oxidative phosphorylation and Rho kinase inhibition, decreased phenylephrine-induced contractions in aortae with PVAT from HFD-fed mice. O2.- and H2 O2 were increased in PVAT from HFD-fed mice. Mitochondrial respiration analysis revealed decreased O2 consumption rates in PVAT from HFD-fed mice. TNF-α inhibition reduced H2 O2 levels in PVAT from HFD-fed mice. PVAT dysfunction, i.e. increased contraction to phenylephrine in PVAT-intact aortae, was not observed in HFD-obese mice lacking TNF-α receptors. Generation of H2 O2 was prevented in PVAT from TNF-α receptor deficient obese mice. TNF-α-induced mitochondrial oxidative stress is a key and novel mechanism involved in obesity-associated PVAT dysfunction. These findings elucidate molecular mechanisms whereby oxidative stress in PVAT could affect 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.

Abstract 12544: Evidence for Involvement of Inflammatory Changes of Perivascular Adipose Tissue in the Pathogenesis of Coronary Hyperconstricting Responses Induced by Drug-Eluting Stent in Pigs in vivo -Impact of Fluorodeoxyglucose Positron Emission Tomography Imaging

Background: Recent studies suggested that perivascular adipose tissue (PVAT) play important roles as a source of various inflammatory mediators in the pathogenesis of cardiovascular disease. We thus tested our hypothesis that inflammatory changes in the coronary PVAT are associated with coronary hyperconstricting responses after drug-eluting stent (DES) implantation by using FDG PET. Methods: Everolimus-eluting stents (EES) were randomly implanted in pigs into either the left anterior descending or circumflex coronary artery while non-stented artery was used as a control. After 1 month, coronary vasoconstricting responses to intracoronary serotonin were examined by coronary angiography in vivo, followed by FDG PET/CT ex vivo imaging and autoradiography for measurement of FDG uptake. Results: Coronary vasoconstricting responses were significantly enhanced at the edges of the EES site compared with the control site (P<0.01, n=40) (Figures A-C). Notably, FDG PET/CT imaging showed enhanced FDG uptake at the EES-implanted coronary segment with significant association between the target to background ratio and the extent of coronary vasoconstricting responses (P<0.01) (Figures D-F). In addition, autoradiography showed that the FDG accumulation was markedly enhanced at the edge of the EES site compared with the control site and was significantly associated with the extent of coronary vasoconstricting responses (P<0.01) (Figures G-J, O). Furthermore, histological analysis and RT-PCR showed that the extent of inflammatory changes in the coronary PVAT were significantly enhanced at the edges of the EES site compared with the control site (Figures K-N). Conclusions: These results demonstrate for the first time that inflammatory changes in the coronary PVAT are involved in the pathogenesis of DES-induced coronary hyperconstricting responses in pigs in vivo and that FDG PET imaging may be useful for assessment of coronary PVAT inflammation.

Abstract 19716: Role of Aldose Reductase in Perivascular Adipose Tissue and Vascular Dysfunction in Short-Term Diet-Induced Obesity

Obesity is a risk factor for diabetes and cardiovascular (CVD) disease, and the quantity of perivascular adipose tissue (PVAT) associates with CVD risk. To test the hypothesis that changes in PVAT are causal in diet-induced vascular dysfunction, mice (wild type, WT and aldose reductase-null, ARKO, an obesity-sensitive model) were fed a low fat chow diet (10% kcal fat) or high fat chow diet (HFD; 60% kcal fat) for 4 weeks (short-term) in either 8 weeks old or 18 weeks old C57 mice (n=4-6/group). After 4 weeks, body weight and lean and fat mass was measured (DexaScan). Vascular, endothelial and PVAT function and structure were measured in isolated thoracic aorta without and with PVAT in response high potassium solution (100 mM HIK), phenylephrine (PE), acetylcholine (ACh), thromboxane A2 analog (U46619) and sodium nitroprusside (SNP). As expected, HFD increased body weight in all groups although ARKO mice (young and old) gained significantly more body weight, fat grams (whole body, epididymal), and % body fat when compared with age-matched WT mice. Similarly, aortic PVAT mass increased in ARKO mice indicating that PVAT growth mirrored visceral adiposity induced by short-term HFD feeding and enhanced in ARKO mice. PVAT significantly enhanced HIK-induced contractions and SNP-stimulated relaxations (%), decreased U46619-induced tension but neither altered PE-stimulated contraction nor ACh-induced relaxation (%) in isolated aorta of LFD-fed WT. Several of these PVAT effects were altered by age, AR deletion and 4-weeks of HFD feeding. For example, PVAT rescued endothelial dysfunction (ACh, -84.0±7.7%) detected as decreased ACh-induced relaxation in aorta without PVAT (ACh, -43.6±6.8%, p<0.05) of 22-week WT mice fed HFD, indicating that short-term HFD induces compensatory PVAT changes that counteract deleterious endothelium changes -- a novel finding. Effects of PVAT were only slightly modified in ARKO mice despite a greater mass of PVAT, indicating a complicated role of AR deletion in PVAT. These data add to a growing literature that reveals a complex, integrative vascular function of PVAT that is modulated during obesity and metabolic syndrome.

Endovascular Injury Induces Rapid Phenotypic Changes in Perivascular Adipose Tissue

Accumulating evidence suggests that adipose tissue not only stores energy but also secretes various bioactive substances called adipocytokines. Periadventitial fat is distributed ubiquitously around arteries throughout the body. It was reported that inflammatory changes in the periadventitial fat may have a direct role in the pathogenesis of vascular diseases accelerated by obesity. We investigated the effect of endovascular injury on the phenotype of perivascular fat. Endovascular injury significantly upregulated proinflammatory adipocytokines and downregulated adiponectin within periadventitial fat tissue in models of mouse femoral artery wire injury and rat iliac artery balloon injury. Genetic disruption of tumor necrosis factor (TNF)-alpha attenuated upregulation of proinflammatory adipocytokine expression, with reduced neointimal hyperplasia after vascular injury. Local delivery of TNF-alpha to the periadventitial area enhanced inflammatory adipocytokine expression, which was associated with augmented neointimal hyperplasia in TNF-alpha-deficient mice. Conditioned medium from a coculture of 3T3-L1 and RAW264 cells stimulated vascular smooth muscle cell proliferation. An anti-TNF-alpha neutralizing antibody in the coculture abrogated the stimulating effect of the conditioned medium. Our findings indicate that endovascular injury induces rapid and marked changes in perivascular adipose tissue, mainly mediated by TNF-alpha. It is suggested that the phenotypic changes in perivascular adipose tissue may have a role in the pathogenesis of neointimal hyperplasia after angioplasty.

Early alterations in vascular contractility associated to changes in fatty acid composition and oxidative stress markers in perivascular adipose tissue

AimTo test the early effect of fructose-induced changes in fatty acid composition and oxidative stress markers in perivascular adipose tissue (PVAT) upon vascular contractility.MethodsAdult male Wistar rats were fed a commercial diet without (CD) or with 10% fructose (FRD) in the drinking water for 3 weeks. We measured plasma metabolic parameters, lipid composition and oxidative stress markers in aortic PVAT. Vascular contractility was measured in aortic rings sequentially, stimulated with serotonin (5-HT) and high K+-induced depolarization using intact and thereafter PVAT-deprived rings.ResultsComparable body weights were recorded in both groups. FRD rats had increased plasma triglyceride and fructosamine levels. Their PVAT had an increased saturated to mono- or poly-unsaturated fatty acid ratio, a significant decrease in total superoxide dismutase and glutathione peroxidase activities and in the total content of glutathione. Conversely, lipid peroxidation (TBARS), nitric oxide content, and gluthathione reductase activity were significantly higher, indicating an increase in oxidative stress. In aortic rings, removal of PVAT increased serotonin-induced contractions, but the effect was significantly lower in rings from FRD rats. This effect was no longer observed when the two contractions were performed in PVAT-deprived rings. PVAT did not affect the contractions triggered by high K+-induced depolarization either in CD or FRD rats.ConclusionsFRD induces multiple metabolic and endocrine systemic alterations which also alter PVAT and the vascular relaxant properties of this tissue. The changes in PVAT would affect its paracrine modulation of vascular function.

Abstract 5169: Endovascular Injury Induces Rapid Phenotypic Changes in Perivascular Adipose Tissue

Background: It was reported that the serum levels of circulating proinflammatory cytokines are increased in overweight people with enhanced accumulation of visceral fat. In contrast to visceral fat, little attention has been paid to the role of perivascular fat in the pathogenesis of obesity-associated diseases. Here, we investigated the effect of endovascular injury on the phenotype of perivascular fat. Methods and Results: First, endovascular injury significantly down-regulated adiponectin and up-regulated proinflammatory adipocytokines, TNF-alpha, IL-6, PAI-1 and MCP-1 within perivascular fat tissue in models of murine femoral artery wire injury and rat iliac artery balloon injury (p<0.05). Second, diet-induced obesity augmented endovascular injury-induced up-regulation of proinflammatory adipocytokines within perivascular fat tissue (p<0.05) and neointimal hyperplasia (p<0.05) compared with standard chow diet in wild-type mice. Third, up-regulation of proinflammatory adipocytokines within perivascular fat by endovascular injury was significantly blunted in TNF-alpha deficient mice (p<0.05). Neointima formation was attenuated in TNF-alpha deficient mice compared with wild-type mice (p<0.05). Furthermore, perivascular delivery of TNF-alpha to the femoral artery using osmotic minipump enhanced endovascular injury-induced up-regulation of proinflammatory adipocy-tokines within perivascular fat (p<0.05) and neointimal hyperplasia (p<0.05) compared with contralateral PBS delivered artery in TNF-alpha deficient mice. Fourth, conditioned medium from the coculture of 3T3L1-derived adipocyte and RAW264 macrophage stimulated rat vascular smooth muscle cells proliferation relative to the control medium from 3T3L1-derived adipocyte (p<0.05). Blockade of TNF-alpha in the co-culture using an anti-TNF-alpha neutralizing antibody reduced the stimulatory activity of the condition medium (p<0.05). Conclusions: Our findings indicate that endovascular injury induces rapid and marked changes in perivascular adipose tissue, mainly mediated by TNF-alpha. It is suggested that the phenotypic changes in perivascular adipose tissue may have a role in the pathogenesis of neointimal hyperplasia after angioplasty.