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Background: Adaptation of fat depots to change in fuel availability is critical for metabolic flexibility and cardiometabolic health. The mechanisms responsible for fat depot-specific lipid sensing and shuttling remain elusive. Adipose tissue microvascular endothelial cells (AT-EC) regulates bidirectional fatty acid fluxes depending on fed or fasted state. How AT-EC sense and adapt to metabolic changes according to AT location remains to be established. Methods: We combined transcriptional analysis of native human AT-EC together with in vitro approaches in primary human AT-EC and in vivo and ex vivo studies of mice under fed and fasted conditions. Results: Transcriptional large-scale analysis of human AT-EC isolated from gluteofemoral and abdominal subcutaneous AT revealed that the endothelium exhibits a fat depot–specific signature associated with lipid handling and Notch signaling enrichment. We uncovered a functional link between metabolic status and endothelial DLL4 (delta-like canonical notch ligand 4), which decreases with fasting. DLL4 regulates fatty acid uptake through nontranscriptional modulation of macropinocytosis-dependent long chain fatty acid uptake. Importantly, the changes in DLL4 expression, in response to energy transition state, is impaired under obesogenic conditions, an early alteration coinciding with a defect in systemic fatty acid fluxes adaptation and a resistance to weight loss. Conclusions: DLL4 is a major actor in the adaptive mechanisms of AT-EC to regulate lipid fluxes. It likely contributes to fat depot-dependent metabolism in response to energy transition states. AT-EC alteration with obesity may favor metabolic inflexibility and the development of cardiometabolic disorders.

Periprostatic adipose tissue (PPAT) abundance correlates with prostate cancer progression, but the mechanism remains unexplained. Here, we used a statistical approach to define abundant PPAT by normalizing PPAT volume to prostate volume in a cohort of 351 patients with a linear regression model. Applying this definition, we find tumors specifically from patients with abundant PPAT exhibit several hallmarks of aggressiveness, suggesting that PPAT abundance might be used to improve risk stratification. We show that abundant PPAT expands by adipocyte hypertrophy but this does not result in inflammation. Extensive extracellular matrix remodeling, notably of the collagen network, and decreased expression of mechano-sensing proteins in adipocytes explains this inflammation-free expansion by decreasing the mechanical constraints on the adipocytes. Moreover, collagen VI degradation in abundant PPAT is associated with production of endotrophin, a matrikine that promotes cancer progression. We find high levels of endotrophin specifically in the urine of patients with abundant PPAT, indicating the clinical relevance of our findings.SummaryThe abundance of periprostatic adipose tissue favors prostate cancer aggressiveness. The increase in extracellular matrix remodeling that occurs in expanded periprostatic fat allows adipocyte hypertrophy without tissue inflammation and generates a matrikine, endotrophin, which favors tumor progression.

International audience; Senescence is a key event in the impairment of adipose tissue (AT) function with obesity and aging but the underlying molecular and cellular players remain to be fully defined, particularly with respect to the human AT progenitors. We have found distinct profiles of senescent progenitors based on AT location between stroma from visceral versus subcutaneous AT. In addition to flow cytometry, we characterized the location differences with transcriptomic and proteomic approaches, uncovering the genes and developmental pathways that are underlying replicative senescence. We identified key components to include INBHA as well as SFRP4 and GREM1, antagonists for the WNT and BMP pathways, in the senescence-associated secretory phenotype and NOTCH3 in the senescence-associated intrinsic phenotype. Notch activation in AT progenitors inhibits adipogenesis and promotes myofibrogenesis independently of TGFβ. In addition, we demonstrate that NOTCH3 is enriched in the premyofibroblast progenitor subset, which preferentially accumulates in the visceral AT of patients with an early obesity trajectory. Herein, we reveal that NOTCH3 plays a role in the balance of progenitor fate determination preferring myofibrogenesis at the expense of adipogenesis. Progenitor NOTCH3 may constitute a tool to monitor replicative senescence and to limit AT dysfunction in obesity and aging.

International audience; White adipose tissue accumulates at various sites throughout the body and some adipose tissue depots exist in close proximity to organs, whose function they could influence in a paracrine manner. Prostate gland is surrounded by a poorly characterized adipose depot called periprostatic adipose tissue (PPAT) playing emerging roles in prostate-related disorders. Unlike all other adipose depots, PPAT secretes pro-inflammatory cytokines even in lean individuals and does not increase in volume during obesity. These unique features remain unexplained due to the poor structural and functional characterization of this tissue. We characterized the structural organization of PPAT in patients in comparison to abdominopelvic adipose tissue (APAT), an extraperitoneal adipose depot whose accumulation is correlated to BMI. Confocal microscopy followed by 3D reconstructions showed a sparse vascular network in PPAT when compared with that in APAT, suggesting that this tissue is hypoxic. Unbiased comparisons of PPAT and APAT transcriptomes found that most differentially expressed genes were related to the hypoxia response. High levels of the hypoxia-inducible factor HIF-2α confirmed the presence of an adaptive response to hypoxia in PPAT. This chronic hypoxic state was associated with inflammation and fibrosis, which were not further upregulated by obesity. This fibrosis and inflammation explain the failure of PPAT to expand in obesity and open new mechanistic avenues to explain its role in prostate-related disorders including cancer

Purpose Excessive fat mass accumulation in obesity leads to diverse metabolic disorders, increased risks of cardiovascular diseases and in some cases, mortality. The aim of this study was to screen the actions of botanical extracts intended for oral use on human adipose tissue, using an in vitro screening model combining human intestinal cells with human adipose cells. This was to find the most effective extracts on lipid accumulation, UCP1 expression and ATP production in pre-adipocytes and on adipocyte lipolysis. Methods In this study, 25 individual plant extracts were screened for their effects on human adipose cells. Consequently, an original in vitro model was set up using the Caco-2 cell line, to mimic the intestinal passage of the extracts and then exposing human adipose cells to them. The biological actions of extracts were thus characterized, and compared with a coffee extract standard. The most effective extracts, and their combinations, were retained for their actions on lipid accumulation, the expression of the thermogenic effector UCP1 and ATP production in pre-adipocytes as well as on lipolysis activity of mature adipocytes. Results The biphasic culture system combining human Caco-2 cells with human adipose cells was verified as functional using the green coffee extract standard. Out of the 25 plant extracts studied, only 7 and their combinations were retained due to their potent effects on adipose cells biology. The data showed that compared to the coffee extract standard, Immortelle, Catechu, Carrot and Rose hip extracts were the most effective in reducing lipid accumulation and increased UCP1 expression in human pre-adipocytes. Conclusion This study reveals the potential inhibitory effects on lipid accumulation and thermogenic activity of Immortelle, Catechu, Carrot and Rose hip extracts, and for the first time synergies in their combinations, using an in vitro model mimicking as closely as possible, human intestinal passage linked to adipose cells. These findings need to be confirmed by in vivo trials.

Tyramine is found in foodstuffs, the richest being cheeses, sausages, and wines. Tyramine has been recognized to release catecholamines from nerve endings and to trigger hypertensive reaction. Thereby, tyramine-free diet is recommended for depressed patients treated with irreversible inhibitors of monoamine oxidases (MAO) to limit the risk of hypertension. Tyramine is a substrate of amine oxidases and also an agonist at trace amine-associated receptors. Our aim was to characterize the dose-dependent effects of tyramine on human adipocyte metabolic functions. Lipolytic activity was determined in adipocytes from human subcutaneous abdominal adipose tissue. Glycerol release was increased by a fourfold factor with classical lipolytic agents (1 μM isoprenaline, 1 mM isobutylmethylxanthine) while the amine was ineffective from 0.01 to 100 μM and hardly stimulatory at 1 mM. Tyramine exhibited a partial antilipolytic effect at 100 μM and 1 mM, which was similar to that of insulin but weaker than that obtained with agonists at purinergic A1 receptors, α2-adrenoceptors, or nicotinic acid receptors. Gi-protein blockade by Pertussis toxin abolished all these antilipolytic responses save that of tyramine. Indeed, tyramine antilipolytic effect was impaired by MAO-A inhibition. Tyramine inhibited protein tyrosine phosphatase activities in a manner sensitive to ascorbic acid and amine oxidase inhibitors. Thus, millimolar tyramine restrained lipolysis via the hydrogen peroxide it generates when oxidized by MAO. Since tyramine plasma levels have been reported to reach 0.2 μM after ingestion of 200 mg tyramine in healthy individuals, the direct effects we observed in vitro on adipocytes could be nutritionally relevant only when the MAO-dependent hepato-intestinal detoxifying system is overpassed.

The anti-obesity effects of resveratrol shown in rodents are not transposed into an efficient therapy of human obesity. Consequently, the search for molecules mimicking or surpassing resveratrol actions is ongoing. The natural phenolic compound pterostilbene exhibits beneficial health effects and has the capacity to limit fat mass in animal models. In this study, we tested whether pterostilbene modulates triacylglycerol accumulation/breakdown. Prolonged exposure to pterostilbene or resveratrol inhibited adipocyte differentiation in 3T3-F442A preadipocytes. Acute effects on lipolysis, antilipolysis and lipogenesis were determined for pterostilbene in mouse adipocytes, and compared with resveratrol. Pterostilbene was also tested on glycerol release and glucose uptake in subcutaneous human adipocytes. Dose–response analyses did not reveal a clear lipolytic effect in both species. The antilipolytic effect of insulin was improved by pterostilbene at 1–10 μM in mouse fat cells only, while at 1 mM, the phenolic compound was antilipolytic in human fat cells in a manner not additive to insulin. Pterostilbene dose-dependently inhibited glucose incorporation into lipids similarly to resveratrol and caffeine. However, only the former did not inhibit insulin-stimulated glucose uptake. Indeed, pterostilbene abolished the insulin lipogenic effect without inhibiting its antilipolytic action and rapid activation of glucose uptake. Pterostilbene therefore exhibits a unique panel of direct interactions with adipocytes that relies on its reported anti-obesity and antidiabetic properties. Copyright © 2017 John Wiley & Sons, Ltd.

Resume Les etudes menees ces dernieres annees ont remis en cause la vision traditionnelle du systeme immunitaire et ont permis de caracteriser des populations immunes residentes dans les depots adipeux mettant en lumiere : 1) le role de barriere immunitaire de ces tissus ; 2) la contribution du systeme immunitaire tissulaire dans le maintien d’une homeostasie metabolique locale et systemique ; 3) les alterations des interrelations metabolisme/immunite dans des contextes pathologiques et avec le vieillissement. Cette revue decrit les donnees recentes sur les macrophages et lymphocytes residents dans les depots adipeux.

Introduction Accumulation of adipose tissue in the central part of the body arising with obesity and aging, is associated with metabolic inflexibility and the development of cardiovascular diseases. The cellular actors and pathophysiological mechanisms linking obesity/aging and cardiometabolic abnormalities remain to be clearly identified. Our data support that microvascular endothelial cells from the adipose tissue (EC-AT) are a major determinant of metabolic flexibility, in particular through their ability to regulate bidirectional fatty acid (FA) fluxes. We hypothesize that alteration of this function contributes to the emergence of cardiometabolic disorders associated with natural and accelerated aging. Objective Our objective is to gain insight into the ability of EC-AT to sense and adapt to metabolic clues and regulate FA fluxes accordingly. Ultimately, our goal is to identify original approaches targeting the endothelium to maintain and/or restore metabolic flexibility and hamper the progression of aging-related cardiovascular disorders. Among the putative molecular mechanisms involved in the regulation of transendothelial FA fluxes, we focused our attention on Notch signaling. Method We use native and primary microvascular EC isolated from human (CD45-/CD34+/CD31+) and mouse (CD45-/SCA1+/CD31+) adipose depots. Results In vivo and in vitro we observe that endothelial-Notch activity is regulated by nutritional status. In particular, the ligand DLL4 is downregulated by fasting and AMPK activation. Using human primary EC-AT, we show that DLL4 regulates long-chain FA uptake through transcriptional and non-transcriptional processes. Conclusion Our data highlight an original role for DLL4 as metabolic sensor in adipose depots that relays transcriptional and functional clues to the endothelium. In particular, DLL4 level likely defines the ability of EC-AT to rapidly adapt and handle lipid fluxes and contributes to the regulation of metabolic flexibility.

Objective— Adipose tissue (AT) dysfunction associated with obesity or aging is a major cause for lipid redistribution and the progression of cardiometabolic disorders. Our goal is to decipher the contribution of human AT microvascular endothelial cells (ECs) in the maintenance of fatty acid (FA) fluxes and the impact of senescence on their function. Approach and Results— We used freshly isolated primary microvascular ECs from human AT. Our data identified the endothelial FA handling machinery including FATPs (FA transport proteins) FATP1, FATP3, FATP4, and CD36 as well as FABP4 (FA binding protein 4). We showed that PPARγ (peroxisome proliferator–activated receptor gamma) regulates the expression of FATP1, CD36, and FABP4 and is a major regulator of FA uptake in human AT EC (hATEC). We provided evidence that endothelial PPARγ activity is modulated by senescence. Indeed, the positive regulation of FA transport by PPARγ agonist was abolished, whereas the emergence of an inflammatory response was favored in senescent hATEC. This was associated with the retention of nuclear FOXO1 (forkhead box protein O1), whereas nuclear PPARγ translocation was impaired. Conclusions— These data support the notion that PPARγ is a key regulator of primary hATEC function including FA handling and inflammatory response. However, the outcome of PPARγ activation is modulated by senescence, a phenomenon that may impact the ability of hATEC to properly respond to and handle lipid fluxes. Finally, our work highlights the role of hATEC in the regulation of FA fluxes and reveals that dysfunction of these cells with accelerated aging is likely to participate to AT dysfunction and the redistribution of lipids.

The anti-obesity effects of resveratrol shown in rodents are not transposed into an efficient therapy of human obesity. Consequently, the search for molecules mimicking or surpassing resveratrol actions is ongoing. The natural phenolic compound pterostilbene exhibits beneficial health effects and has the capacity to limit fat mass in animal models. In this study, we tested whether pterostilbene modulates triacylglycerol accumulation/breakdown. Prolonged exposure to pterostilbene or resveratrol inhibited adipocyte differentiation in 3T3-F442A preadipocytes. Acute effects on lipolysis, antilipolysis and lipogenesis were determined for pterostilbene in mouse adipocytes, and compared with resveratrol. Pterostilbene was also tested on glycerol release and glucose uptake in subcutaneous human adipocytes. Dose-response analyses did not reveal a clear lipolytic effect in both species. The antilipolytic effect of insulin was improved by pterostilbene at 1-10 μM in mouse fat cells only, while at 1 mM, the phenolic compound was antilipolytic in human fat cells in a manner not additive to insulin. Pterostilbene dose-dependently inhibited glucose incorporation into lipids similarly to resveratrol and caffeine. However, only the former did not inhibit insulin-stimulated glucose uptake. Indeed, pterostilbene abolished the insulin lipogenic effect without inhibiting its antilipolytic action and rapid activation of glucose uptake. Pterostilbene therefore exhibits a unique panel of direct interactions with adipocytes that relies on its reported anti-obesity and antidiabetic properties. Copyright © 2017 John WileySons, Ltd.

AIM To assess in rodent and human adipocytes the antilipolytic capacity of hexaquis(benzylammonium) decavanadate (B6V10), previously shown to exert antidiabetic effects in rodent models, such as lowering free fatty acids (FFA) and glucose circulating levels. METHODS Adipose tissue (AT) samples were obtained after informed consent from overweight women undergoing plastic surgery. Comparison of the effects of B6V10 and reference antilipolytic agents (insulin, benzylamine, vanadate) on the lipolytic activity was performed on adipocytes freshly isolated from rat, mouse and human AT. Glycerol release was measured using colorimetric assay as an index of lipolytic activity. The influence of B6V10 and reference agents on glucose transport into human fat cells was determined using the radiolabelled 2-deoxyglucose uptake assay. RESULTS In all the species studied, B6V10 exhibited a dose-dependent inhibition of adipocyte lipolysis when triglyceride breakdown was moderately enhanced by β-adrenergic receptor stimulation. B6V10 exerted on human adipocyte a maximal lipolysis inhibition of glycerol release that was stronger than that elicited by insulin. However, B6V10 did not inhibit basal and maximally stimulated lipolysis. When incubated at dose ≥ 10 μmol/L, B6V10 stimulated by twofold the glucose uptake in human fat cells, but - similarly to benzylamine - without reaching the maximal effect of insulin, while it reproduced one-half of the insulin-stimulation of lipogenesis in mouse fat cells. CONCLUSION B6V10 exerts insulin-like actions in adipocytes, including lipolysis inhibition and glucose transport activation. B6V10 may be useful in limiting lipotoxicity related to obesity and insulin resistance.

Obesity-associated inflammation contributes to the development of metabolic diseases. Although brite adipocytes have been shown to ameliorate metabolic parameters in rodents, their origin and differentiation remain to be characterized in humans. Native CD45−/CD34+/CD31− cells have been previously described as human adipocyte progenitors. Using two additional cell surface markers, MSCA1 (tissue nonspecific alkaline phosphatase) and CD271 (nerve growth factor receptor), we are able to partition the CD45−/CD34+/CD31− cell population into three subsets. We establish serum-free culture conditions without cell expansion to promote either white/brite adipogenesis using rosiglitazone, or bone morphogenetic protein 7 (BMP7), or specifically brite adipogenesis using 3-isobuthyl-1-methylxanthine. We demonstrate that adipogenesis leads to an increase of MSCA1 activity, expression of white/brite adipocyte-related genes, and mitochondriogenesis. Using pharmacological inhibition and gene silencing approaches, we show that MSCA1 activity is required for triglyceride accumulation and for the expression of white/brite-related genes in human cells. Moreover, native immunoselected MSCA1+ cells exhibit brite precursor characteristics and the highest adipogenic potential of the three progenitor subsets. Finally, we provided evidence that MSCA1+ white/brite precursors accumulate with obesity in subcutaneous adipose tissue (sAT), and that local BMP7 and inflammation regulate brite adipogenesis by modulating MSCA1 in human sAT. The accumulation of MSCA1+ white/brite precursors in sAT with obesity may reveal a blockade of their differentiation by immune cells, suggesting that local inflammation contributes to metabolic disorders through impairment of white/brite adipogenesis. Stem Cells 2015;33:1277–1291