Loss of anti-contractile effect of perivascular adipose tissue in offspring of obese rats

Perivascular Adipose Tissue and Perivascular Adipose Tissue-Derived Extracellular Vesicles: New Insights in Vascular Disease

Perivascular adipose tissue (PVAT) is a special deposit of fat tissue surrounding the vasculature. Previous studies suggest that PVAT modulates the vasculature function in physiological conditions and is implicated in the pathogenesis of vascular diseases. Understanding how PVAT influences vasculature function and vascular disease progression is important. Extracellular vesicles (EVs) are novel mediators of intercellular communication. EVs encapsulate molecular cargo such as proteins, lipids, and nucleic acids. EVs can influence cellular functions by transferring the carried bioactive molecules. Emerging evidence indicates that PVAT-derived EVs play an important role in vascular functions under health and disease conditions. This review will focus on the roles of PVAT and PVAT-EVs in obesity, diabetic, and metabolic syndrome-related vascular diseases, offering novel insights into therapeutic targets for vascular diseases.

Interleukin-10 deficiency induces thoracic perivascular adipose tissue whitening and vascular remodeling

Perivascular adipose tissue (PVAT) is an adipose layer, surrounding blood vessels, with a local modulatory role. Interleukin-10 (IL-10) has been shown to modulate vascular tissue. This study aimed to characterize the endogenous role of IL-10 in vascular remodeling, and PVAT phenotyping. Thoracic aortic segments from control (C57BL/6J) and IL-10 knockout (IL-10-/-) male mice were used. Analyzes of aorta/PVAT morphometry, and elastin, collagen and reticulin deposition were performed. Tissue uncoupling protein 1 (UCP1) was accessed by Western blotting. Endogenous absence of IL-10 reduced total PVAT area (p = 0.0310), and wall/lumen ratio (p = 0.0024), whereas increased vascular area and thickness (p < 0.0001). Total collagen deposition was augmented in IL-10-/-, but under polarized light, the reduction of collagen-I (p = 0.0075) and the increase of collagen-III (p = 0.0055) was found, simultaneously with reduced elastic fibers deposition (p = 0.0282) and increased deposition of reticular fibers (p < 0.0001). Adipocyte area was augmented in the IL-10 absence (p = 0.0225), and UCP1 expression was reduced (p = 0.0420). Moreover, relative frequency of white adipose cells and connective tissue was augmented in IL-10-/- (p < 0.0001), added to a reduction in brown adipose cells (p < 0.0001). Altogether, these data characterize aorta PVAT from IL-10-/- as a white-like adipocyte phenotype. Endogenous IL-10 prevents vascular remodeling and favors a brown-like adipocyte phenotype, suggesting a modulatory role for IL-10 in PVAT plasticity.

Innervation of adipocytes is limited in mouse perivascular adipose tissue

Perivascular adipose tissue (PVAT) regulates vascular tone by releasing anticontractile factors. These anticontractile factors are driven by processes downstream of adipocyte stimulation by norepinephrine; however, whether norepinephrine originates from neural innervation or other sources is unknown. The goal of this study was to test the hypothesis that neurons innervating PVAT provide the adrenergic drive to stimulate adipocytes in aortic and mesenteric perivascular adipose tissue (aPVAT and mPVAT), and white adipose tissue (WAT). Healthy male and female mice (8-13 wk) were used in all experiments. Expression of genes associated with synaptic transmission were quantified by qPCR and adipocyte activity in response to neurotransmitters and neuron depolarization was assessed in AdipoqCre+;GCaMP5g-tdTf/WT mice. Immunostaining, tissue clearing, and transgenic reporter lines were used to assess anatomical relationships between nerves and adipocytes. Although synaptic transmission component genes are expressed in adipose tissues (aPVAT, mPVAT, and WAT), strong nerve stimulation with electrical field stimulation does not significantly trigger calcium responses in adipocytes. However, norepinephrine consistently elicits strong calcium responses in adipocytes from all adipose tissues studied. Bethanechol induces minimal adipocyte responses. Imaging neural innervation using various techniques reveals that nerve fibers primarily run alongside blood vessels and rarely branch into the adipose tissue. Although nerve fibers are associated with blood vessels in adipose tissue, they demonstrate limited anatomical and functional interactions with adjacent adipocytes, challenging the concept of classical innervation. These findings dispute the significant involvement of neural input in regulating PVAT adipocyte function and emphasize alternative mechanisms governing adrenergic-driven anticontractile functions of PVAT.NEW & NOTEWORTHY This study challenges prevailing views on neural innervation in perivascular adipose tissue (PVAT) and its role in adrenergic-driven anticontractile effects on vasculature. Contrary to existing paradigms, limited anatomical and functional connections were found between PVAT nerve fibers and adipocytes, underscoring the importance of exploring alternative mechanistic pathways. Understanding the mechanisms involved in PVAT's anticontractile effects is critical for developing potential therapeutic interventions against dysregulated vascular tone, hypertension, and cardiovascular disease.

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.

Adipocyte-derived relaxing factor-a fat load to be learnt

Properties of the radial artery (RA) have been of immense interest to both laboratory scientists and clinicians, especially due to the increasing utilization of RA as a second-choice conduit for coronary artery bypass graft (CABG), after left internal mammary artery.

Maternal Obesity Programming of Perivascular Adipose Tissue and Associated Immune Cells: An Understudied Area With Few Answers and Many Questions

At present, the worldwide prevalence of obesity has become alarmingly high with estimates foreshadowing a continued escalation in the future. Furthermore, there is growing evidence attributing an individual’s predisposition for developing obesity to maternal health during gestation. Currently, 60% of pregnancies in the US are to either overweight or obese mothers which in turn contributes to the persistent rise in obesity rates. While obesity itself is problematic, it conveys an increased risk for several diseases such as diabetes, inflammatory disorders, cancer and cardiovascular disease (CVD). Additionally, as we are learning more about the mechanisms underlying CVD, much attention has been brought to the role of perivascular adipose tissue (PVAT) in maintaining cardiovascular health. PVAT regulates vascular tone and for a significant number of individuals, obesity elicits PVAT disruption and dysregulation of vascular function. Obesity elicits changes in adipocyte and leukocyte populations within PVAT leading to an inflammatory state which promotes vasoconstriction thereby aiding the onset/progression of CVD. Our current understanding of obesity, PVAT and CVD has only been examined at the individual level without consideration for a maternal programming effect. It is unknown if maternal obesity affects the propensity for PVAT remodeling in the offspring, thereby enhancing the obesity/CVD link, and what role PVAT leukocytes play in this process. This perspective will focus on the maternal contribution of the interplay between obesity, PVAT disruption and CVD and will highlight the leukocyte/PVAT interaction as a novel target to stem the tide of the current obesity epidemic and its secondary health consequences.

Deletion of Seipin Attenuates Vascular Function and the Anticontractile Effect of Perivascular Adipose Tissue

Seipin locates in endoplasmic reticulum (ER) and regulates adipogenesis and lipid droplet formation. Deletion of Seipin has been well-demonstrated to cause severe general lipodystrophy, however, its role in maintaining perivascular adipose tissue (PVAT) and vascular homeostasis has not been directly assessed. In the present study, we investigated the role of Seipin in mediating the anticontractile effect of PVAT and vascular function. Seipin expression in PVAT and associated vessels were detected by qPCR and western-blot. Seipin is highly expressed in PVAT, but hardly in vessels. Structural and functional alterations of PVAT and associated vessels were compared between Seipin^−/− mice and WT mice. In Seipin^−/− mice, aortic and mesenteric PVAT were significantly reduced in mass and adipose-derived relaxing factors (ADRFs) secretion, but increased in macrophage infiltration and ER stress, as compared with those in WT mice. Aortic and mesenteric artery rings from WT and Seipin^−/− mice were mounted on a wire myograph. Vasoconstriction and vasodilation were studied in vessels with and without PVAT. WT PVAT augmented relaxation but not Seipin^−/− PVAT, which suggest impaired anticontractile function in PVAT of Seipin^−/− mice. Thoracic aorta and mesenteric artery from Seipin^−/− mice had impaired contractility in response to phenylephrine (PHE) and relaxation to acetylcholine (Ach). In conclusion, Seipin deficiency caused abnormalities in PVAT morphology and vascular functions. Our data demonstrated for the first time that Seipin plays a critical role in maintaining PVAT function and vascular homeostasis.

Role of Perivascular Adipose Tissue-Derived Adiponectin in Vascular Homeostasis

Studies of adipose tissue biology have demonstrated that adipose tissue should be considered as both passive, energy-storing tissue and an endocrine organ because of the secretion of adipose-specific factors, called adipokines. Adiponectin is a well-described homeostatic adipokine with metabolic properties. It regulates whole-body energy status through the induction of fatty acid oxidation and glucose uptake. Adiponectin also has anti-inflammatory and antidiabetic properties, making it an interesting subject of biomedical studies. Perivascular adipose tissue (PVAT) is a fat depot that is conterminous to the vascular wall and acts on it in a paracrine manner through adipokine secretion. PVAT-derived adiponectin can act on the vascular wall through endothelial cells and vascular smooth muscle cells. The present review describes adiponectin's structure, receptors, and main signaling pathways. We further discuss recent studies of the extent and nature of crosstalk between PVAT-derived adiponectin and endothelial cells, vascular smooth muscle cells, and atherosclerotic plaques. Furthermore, we argue whether adiponectin and its receptors may be considered putative therapeutic targets.

Review on multifaceted involvement of perivascular adipose tissue in vascular pathology

Perivascular adipose tissue (PVAT) is a fat tissue deposit that encircles the vasculature. PVAT is traditionally known to protect the vasculature from external stimuli that could cause biological stress. In addition to the protective role of PVAT, it secretes certain biologically active substances known as adipokines that induce paracrine effects on proximate blood vessels. These adipokines influence vascular tones. There are different types of PVAT and they are phenotypically and functionally distinct. These are the white and brown PVATs. Under certain conditions, white PVAT could undergo phenotypic switch to attain a brown PVAT-like phenotype. This type of PVAT is referred to as Beige PVAT. The morphology of adipose tissue is influenced by species, age, and sex. These factors play significant roles in adipose tissue mass, functionality, paracrine activity, and predisposition to vascular diseases. The difficulty that is currently experienced in extrapolating animal models to human physiology could be traceable to these factors. Up till now, the involvement of PVAT in the development of vascular pathology is still not well understood. Brown and white PVAT contribute differently to vascular pathology. Thus, the PVAT could be a therapeutic target in curbing certain vascular diseases. In this review, knowledge would be updated on the multifaceted involvement of PVAT in vascular pathology and also explore its vascular therapeutic potential.

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

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

Gestational intermittent hypoxia induces endothelial dysfunction, reduces perivascular adiponectin and causes epigenetic changes in adult male offspring

KEY POINTS

Obstructive sleep apnoea (OSA) is characterized by intermittent hypoxia, which causes oxidative stress and inflammation and increases the risk of cardiovascular disease. OSA during pregnancy causes adverse maternal and fetal outcomes. The effects of pre-existing OSA in pregnant women on cardiometabolic outcomes in the offspring are unknown. We evaluated basic metabolic parameters, as well as aortic vascular and perivascular adipose tissue (PVAT) function in response to adiponectin, and examined DNA methylation of adiponectin gene promoter in PVAT in 16-week-old adult offspring exposed to gestational intermittent hypoxia (GIH). GIH decreased body weights at week 1 in both male and female offspring, and caused subsequent increases in body weight and food consumption in male offspring only. Adult female offspring had normal levels of lipids, glucose and insulin, with no endothelial dysfunction. Adult male offspring exhibited dyslipidaemia, insulin resistance and hyperleptinaemia. Decreased endothelial-dependent vasodilatation, loss of anti-contractile activity of PVAT and low circulating PVAT adiponectin levels, as well as increased pro-inflammatory gene expression and DNA methylation of adiponectin gene promoter, occurred in adult male offspring. Our results suggest that male offspring of women with OSA could be at risk of developing cardiometabolic disease during adulthood.

ABSTRACT

Perturbations during pregnancy can program the offspring to develop cardiometabolic diseases later in life. Obstructive sleep apnoea (OSA) is a chronic condition that frequently affects pregnancies and leads to adverse fetal outcomes. We assessed the offspring of female mice experiencing gestational intermittent hypoxia (GIH), a hallmark of OSA, for changes in metabolic profiles, aortic nitric oxide (NO)-dependent relaxations, perivascular adipose tissue (PVAT) anti-contractile activities and the responses to adiponectin, and DNA methylation of the adiponectin gene promoter in PVAT tissue. Pregnant mouse dams were exposed to intermittent hypoxic cycles ( F I O 2 21-12%) for 18 days. GIH resulted in lower body weights of pups at week 1, followed by significant weight gain by week 16 of age in male but not female offspring. Plasma lipids, leptin and insulin resistance were higher in GIH male adult offspring. Endothelium-dependent relaxation in response to ACh and the anti-contractile activity of PVAT in the abdominal aorta was reduced in GIH adult male offspring. Incubation of arteries from GIH adult male offspring with adiponectin restored the anti-contractile activity of PVAT. Both circulating and PVAT tissue homogenate levels of adiponectin, as well as gene expression of adiponectin in PVAT, were lower in GIH male offspring, along with an increased gene expression of inflammatory cytokines. Pyrosequencing of adiponectin gene promoter in PVAT showed increased DNA methylation in GIH male offspring. Our results indicate that GIH leads to vascular disease in adult male offspring through PVAT dysfunction, which was associated with low adiponectin levels and epigenetic modifications on the adiponectin gene promoter.

Maternal obesity in pregnancy impacts offspring cardiometabolic health: Systematic review and meta-analysis of animal studies

Obesity before and during pregnancy leads to reduced offspring cardiometabolic health. Here, we systematically reviewed animal experimental evidence of maternal obesity before and during pregnancy and offspring anthropometry and cardiometabolic health. We systematically searched Embase and Medline from inception until January 2018. Eligible publications compared offspring of mothers with obesity to mothers with a normal weight. We performed meta-analyses and subgroup analyses. We also examined methodological quality and publication bias. We screened 2543 publications and included 145 publications (N = 21 048 animals, five species). Essential methodological details were not reported in the majority of studies. We found evidence of publication bias for birth weight. Offspring of mothers with obesity had higher body weight (standardized mean difference (SMD) 0.76 [95% CI 0.60;0.93]), fat percentage (0.99 [0.64;1.35]), systolic blood pressure (1.33 [0.75;1.91]), triglycerides (0.64 [0.42;0.86], total cholesterol (0.46 [0.18;0.73]), glucose level (0.43 [0.24;0.63]), and insulin level (0.81 [0.61;1.02]) than offspring of control mothers, but similar birth weight. Sex, age, or species did not influence the effect of maternal obesity on offspring's cardiometabolic health. Obesity before and during pregnancy reduces offspring cardiometabolic health in animals. Future intervention studies should investigate whether reducing obesity prior to conception could prevent these detrimental programming effects and improve cardiometabolic health of future generations.

Plasticity of Adipose Tissue-Derived Stem Cells and Regulation of Angiogenesis

Adipose tissue is recognized as an important organ with metabolic, regulatory, and plastic roles. Adipose tissue-derived stem cells (ASCs) with self-renewal properties localize in the stromal vascular fraction (SVF) being present in a vascular niche, thereby, contributing to local regulation of angiogenesis and vessel remodeling. In the past decades, ASCs have attracted much attention from biologists and bioengineers, particularly, because of their multilineage differentiation potential, strong proliferation, and migration abilities in vitro and high resistance to oxidative stress and senescence. Current data suggest that the SVF serves as an important source of endothelial progenitors, endothelial cells, and pericytes, thereby, contributing to vessel remodeling and growth. In addition, ASCs demonstrate intriguing metabolic and interlineage plasticity, which makes them good candidates for creating regenerative therapeutic protocols, in vitro tissue models and microphysiological systems, and tissue-on-chip devices for diagnostic and regeneration-supporting purposes. This review covers recent achievements in understanding the metabolic activity within the SVF niches (lactate and NAD+ metabolism), which is critical for maintaining the pool of ASCs, and discloses their pro-angiogenic potential, particularly, in the complex therapy of cardiovascular and cerebrovascular diseases.

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.

C1q/TNF-related protein 9 improves the anti-contractile effects of perivascular adipose tissue via the AMPK-eNOS pathway in diet-induced obese mice

The anti-contractile property of perivascular adipose tissue (PVAT) is abolished through an endothelium-dependent pathway in obesity. C1q/tumor necrosis factor-related protein (CTRP)9 improved endothelial function by promoting endothelium-dependent vasodilatation. The aims of this study were to investigate whether CTRP9 improves the anti-contractile effect of PVAT and protects against PVAT dysfunction in obese mice. The mice were treated with a high-fat diet with or without CTRP9 treatment. Thoracic aortas with or without PVAT (PVAT+ or PVAT-) were prepared, and concentration-dependent responses to phenylephrine were measured. Obese mice showed a significantly increased contractile response, which was suppressed by CTRP9 treatment both with and without PVAT. PVAT significantly reduced the anti-contractile effect in obese mice, which was partially restored by CTRP9 treatment. Treatment of the aortic rings (PVAT+) with inhibitors of AMP protein kinase (AMPK), Akt and endothelial nitric oxide synthase (eNOS) attenuated the beneficial effect of CTRP9 on PVAT. Similar results were observed when we pretreated the aortic rings with CTRP9 ex vivo. CTRP9 significantly enhanced the phosphorylation levels of AMPK, Akt and eNOS, and reduced superoxide production and TNF-α levels in PVAT from obese mice. Our study suggests that CTRP9 enhanced the anti-contractile effect of PVAT and improved PVAT function by activating the AMPK-eNOS pathway in obese mice.

Role of Perivascular Adipose Tissue in Health and Disease

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

Comparisons between perivascular adipose tissue and the endothelium in their modulation of vascular tone

The endothelium is an established modulator of vascular tone; however, the recent discovery of the anti-contractile nature of perivascular adipose tissue (PVAT) suggests that the fat, which surrounds many blood vessels, can also modulate vascular tone. Both the endothelium and PVAT secrete vasoactive substances, which regulate vascular function. Many of these factors are common to both the endothelium and PVAT; therefore, this review will highlight the potential shared mechanisms in the modulation of vascular tone. Endothelial dysfunction is a hallmark of many vascular diseases, including hypertension and obesity. Moreover, PVAT dysfunction is now being reported in several cardio-metabolic disorders. Thus, this review will also discuss the mechanistic insights into endothelial and PVAT dysfunction in order to evaluate whether PVAT modulation of vascular contractility is similar to that of the endothelium in health and disease.

LINKED ARTICLES

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

The Association between High Fat Diet around Gestation and Metabolic Syndrome-related Phenotypes in Rats: A Systematic Review and Meta-Analysis

Numerous rodent studies have evaluated the effects of a maternal high-fat diet (HFD) on later in life susceptibility to Metabolic Syndrome (MetS) with varying results. Our aim was to quantitatively synthesize the available data on effects of maternal HFD around gestation on offspring's body mass, body fat, plasma leptin, glucose, insulin, lipids and systolic blood pressure (SBP). Literature was screened and summary estimates of the effect of maternal HFD on outcomes were calculated by using fixed- or random-effects models. 362 effect sizes from 68 studies together with relevant moderators were collected. We found that maternal HFD is statistically associated with higher body fat, body weight, leptin, glucose, insulin and triglycerides levels, together with increased SBP in offspring later in life. Our analysis also revealed non-significant overall effect on offspring's HDL-cholesterol. A main source of variation among studies emerged from rat strain and lard-based diet type. Strain and sex -specific effects on particular data subsets were detected. Recommendations are suggested for future research in the field of developmental programming of the MetS. Despite significant heterogeneity, our meta-analysis confirms that maternal HFD had long-term metabolic effects in offspring.

The AMP-Related Kinase (AMPK) Induces Ca 2+ -Independent Dilation of Resistance Arteries by Interfering With Actin Filament Formation

Rationale:

Decreasing Ca 2+ sensitivity of vascular smooth muscle (VSM) allows for vasodilation without lowering of cytosolic Ca 2+ . This may be particularly important in states requiring maintained dilation, such as hypoxia. AMP-related kinase (AMPK) is an important cellular energy sensor in VSM. Regulation of Ca 2+ sensitivity usually is attributed to myosin light chain phosphatase activity, but findings in non-VSM identified changes in the actin cytoskeleton. The potential role of AMPK in this setting is widely unknown.

Objective:

To assess the influence of AMPK on the actin cytoskeleton in VSM of resistance arteries with regard to potential Ca 2+ desensitization of VSM contractile apparatus.

Methods and Results:

AMPK induced a slowly developing dilation at unchanged cytosolic Ca 2+ levels in potassium chloride–constricted intact arteries isolated from mouse mesenteric tissue. This dilation was not associated with changes in phosphorylation of myosin light chain or of myosin light chain phosphatase regulatory subunit. Using ultracentrifugation and confocal microscopy, we found that AMPK induced depolymerization of F-actin (filamentous actin). Imaging of arteries from LifeAct mice showed F-actin rarefaction in the midcellular portion of VSM. Immunoblotting revealed that this was associated with activation of the actin severing factor cofilin. Coimmunoprecipitation experiments indicated that AMPK leads to the liberation of cofilin from 14-3-3 protein.

Conclusions:

AMPK induces actin depolymerization, which reduces vascular tone and the response to vasoconstrictors. Our findings demonstrate a new role of AMPK in the control of actin cytoskeletal dynamics, potentially allowing for long-term dilation of microvessels without substantial changes in cytosolic Ca 2+ .

The Role of O-GlcNAcylation in Perivascular Adipose Tissue Dysfunction of Offspring of High-Fat Diet-Fed Rats

Perivascular adipose tissue (PVAT), which reduces vascular contractility, is dysfunctional in the male offspring of rats fed a high-fat diet (HFD), partially due to a reduced NO bioavailability. O-GlcNAcylation of eNOS decreases its activity, thus we investigated the role of O-GlcNAcylation in the prenatal programming of PVAT dysfunction. Female Sprague-Dawley rats were fed either a control (10% fat) or an obesogenic HFD (45% fat) diet for 12 weeks prior to mating, and throughout pregnancy and lactation. Offspring were weaned onto the control diet and were killed at 12 and 24 weeks of age. Mesenteric arteries from the 12-week-old offspring of HFD dams (HFDO) contracted less to U46619; these effects were mimicked by glucosamine in control arteries. PVAT from 12- and 24-week-old controls, but not from HFDO, exerted an anticontractile effect. Glucosamine attenuated the anticontractile effect of PVAT in the vessels from controls but not from HFDO. AMP-activated protein kinase (AMPK) activation (with A769662) partially restored an anticontractile effect in glucosamine-treated controls and HFDO PVAT. Glucosamine decreased AMPK activity and expression in HFDO PVAT, although phosphorylated eNOS expression was only reduced in that from males. The loss of anticontractile effect of HFDO PVAT is likely to result from increased O-GlcNAcylation, which decreased AMPK activity and, in males, decreased NO bioavailability.

'Browning' the cardiac and peri-vascular adipose tissues to modulate cardiovascular risk

Excess visceral adiposity, in particular that located adjacent to the heart and coronary arteries is associated with increased cardiovascular risk. In the pathophysiological state, dysfunctional adipose tissue secretes an array of factors modulating vascular function and driving atherogenesis. Conversely, brown and beige adipose tissues utilise glucose and lipids to generate heat and are associated with improved cardiometabolic health. The cardiac and thoracic perivascular adipose tissues are now understood to be composed of brown adipose tissue in the healthy state and undergo a brown-to-white transition i.e. during obesity which may be a driving factor of cardiovascular disease. In this review we discuss the risks of excess cardiac and vascular adiposity and potential mechanisms by which restoring the brown phenotype i.e. “re-browning” could potentially be achieved in clinically relevant populations.

•

Epicardial, paracardial and thoracic perivascular adipose tissues resemble BAT at birth.

•

Despite ‘whitening’ in early life these depots remain metabolically active and potentially thermogenic into adulthood.

•

Obesity induces further ‘whitening’ and inflammation in these depots likely driving the atherogenesis.

•

Maintaining or inducing the brown phenotype in these depots could prevent atherosclerotic disease.