Adipose Tissue Hypertrophy Research Articles

Purinergic receptor Y2 (P2Y2)- dependent VCAM-1 expression promotes immune cell infiltration in metabolic syndrome.

Sterile inflammation of visceral fat, provoked by dying adipocytes, links the metabolic syndrome to cardiovascular disease. Danger-associated molecular patterns, such as adenosine triphosphate (ATP), are released by activated or dying cells and orchestrate leukocyte infiltration and inflammation via the purinergic receptor P2Y2. The gene expression of ATP receptor P2Y2 did not change in several tissues in the course of obesity, but was increased within epididymal fat. Adipose tissue from P2Y 2-/- mice consuming high-fat diet (HFD) contained less crown-like structures with a reduced frequency of adipose tissue macrophages (ATMs). This was likely due to decreased leukocyte migration because of missing VCAM-1 exposition on P2Y2 deficient hypertrophic adipose tissue endothelial cells. Accordingly, P2Y 2-/- mice showed blunted traits of the metabolic syndrome: they gained less weight compared to P2Y 2+/+ controls, while intake of food and movement behaviour remained unchanged. Liver and adipose tissue were smaller in P2Y 2-/- animals. Insulin tolerance testing (ITT) performed in obese P2Y 2-/- mice revealed a better insulin sensitivity as well as lower plasma C-peptide and cholesterol levels. We demonstrate that interfering with somatic P2Y2 signalling prevents excessive immune cell deposition in diet-induced obesity (DIO), both attenuating adipose tissue inflammation and ameliorating the metabolic phenotype. Thus, blocking the P2Y2 cascade may be a promising strategy to limit metabolic disease and its sequelae.

Assessment of Mechanical Properties of Tissue in Breast Cancer-Related Lymphedema Using Ultrasound Elastography.

Breast cancer-related lymphedema is a consequence of a malfunctioning lymphatic drainage system resulting from surgery or some other form of treatment. In the initial stages, minor and reversible increases in the fluid volume of the arm are evident. As the stages progress over time, the underlying pathophysiology dramatically changes with an irreversible increase in arm volume most likely due to a chronic local inflammation leading to adipose tissue hypertrophy and fibrosis. Clinicians have subjective ways to stage the degree and severity such as the pitting test which entails manually comparing the elasticity of the affected and unaffected arms. Several imaging modalities can be used but ultrasound appears to be the most preferred because it is affordable, safe, and portable. Unfortunately, ultrasonography is not typically used for staging lymphedema, because the appearance of the affected and unaffected arms is similar in B-mode ultrasound images. However, novel ultrasound techniques have emerged, such as elastography, which may be able to identify changes in mechanical properties of the tissue related to detection and staging of lymphedema. This paper presents a novel technique to compare the mechanical properties of the affected and unaffected arms using quasi-static ultrasound elastography to provide an objective alternative to the current subjective assessment. Elastography is based on time delay estimation (TDE) from ultrasound images to infer displacement and mechanical properties of the tissue. We further introduce a novel method for TDE by incorporating higher order derivatives of the ultrasound data into a cost function and propose a novel optimization approach to efficiently minimize the cost function. This method works reliably with our challenging patient data. We collected radio frequency ultrasound data from both arms of seven patients with stage 2 lymphedema, at six different locations in each arm. The ratio of strain in skin, subcutaneous fat, and skeletal muscle divided by strain in the standoff gel pad was calculated in the unaffected and affected arms. The p -values using a Wilcoxon sign-rank test for the skin, subcutaneous fat, and skeletal muscle were 1.24×10-5 , 1.77×10-8 , and 8.11×10-7 respectively, showing differences between the unaffected and affected arms with a very high level of significance.

Chronic Liquid Fructose, but not Glucose, Supplementation Selectively Induces Visceral Adipose Tissue Leptin Resistance and Hypertrophy in Female Sprague-Dawley Rats.

The effect of chronic supplementation with simple-sugar solutions on leptin signaling in liver, hypothalamus, and visceral white adipose tissue (vWAT) is studied, which is designed to mimic the temporal pattern of consumption by humans. Solutions of fructose or glucose are isocalorically supplemented (7 months) in female Sprague-Dawley rats consuming ad libitum rodent chow. After sacrifice, plasma and tissue samples (liver, hypothalamus, and vWAT) are collected. Zoometric parameters, plasma analytes, and the tissue expression and activity of markers of leptin signaling are determined by biochemical and molecular biological methods. The two sugars cause different types of adiposopathy. Both sugars induce increases in plasma nonesterified fatty acids, and leptin resistance in the liver and the hypothalamus. Only fructose-supplemented rats show hyperleptinemia, and increased body weight due to a hypertrophy of vWAT, with no signs of leptin-mediated lipolysis. Glucose-supplemented rats show no significant changes in these parameters but present elevated plasma adiponectin concentrations, lipolysis, and inflammatory markers in vWAT, indicating a shift to a nonexpandable adipose tissue phenotype. Chronic consumption of fructose places a greater burden on metabolic homeostasis than equivalent consumption of glucose, inducing hyperleptinemia, generalized leptin resistance, and increased body weight due to expanded, hypertrophic vWAT.

CTBP1/CYP19A1/estradiol axis together with adipose tissue impacts over prostate cancer growth associated to metabolic syndrome

Metabolic syndrome (MeS) increases prostate cancer (PCa) risk and aggressiveness. C-terminal binding protein 1 (CTBP1) is a transcriptional co-repressor of tumor suppressor genes that is activated by low NAD+ /NADH ratio. Previously, our group established a MeS and PCa mice model that identified CTBP1 as a novel link associating both diseases. We found that CTBP1 controls the transcription of aromatase (CYP19A1), a key enzyme that converts androgens to estrogens. The aim of this work was to investigate the mechanism that explains CTBP1 as a link between MeS and PCa based on CYP19A1 and estrogen synthesis regulation using PCa cell lines, MeS/PCa mice and adipose co-culture systems. We found that CTBP1 and E1A binding protein p300 (EP300) bind to CYP19A1 promoter and downregulate its expression in PC3 cells. Estradiol, through estrogen receptor beta, released CTBP1 from CYP19A1 promoter triggering its transcription and modulating PCa cell proliferation. We generated NSG and C57BL/6J MeS mice by chronically feeding animals with high fat diet. In the NSG model, CTBP1 depleted PCa xenografts showed an increase in CYP19A1 expression with subsequent increment in intratumor estradiol concentrations. Additionally, in C57BL/6J mice, MeS induced hypertrophy, hyperplasia and inflammation of the white adipose tissue, which leads to a proinflammatory phenotype and increased serum estradiol concentration. Thus, MeS increased PCa growth and Ctbp1, Fabp4 and IL-6 expression levels. These results describe, for the first time, a novel CTBP1/CYP19A1/Estradiol axis that explains, in part, the mechanism for prostate tumor growth increase by MeS.

Mesenteric Adipose Tissue Alterations in Crohn's Disease Are Associated With the Lymphatic System.

Mesenteric fat wrapping and thickening are typical characteristics of Crohn's disease (CD). The purpose of this study was to explore the cause of mesenteric adipose hypertrophy and analyze the role of lymphatic vessels in mesenteric adipose tissue in CD. Twenty-three CD patients who underwent ileocolonic resection were included. In CD patients, specimens were obtained from hypertrophic mesenteric adipose tissue (htMAT) next to the diseased ileum. The mesenteric lymphatic vessels in mesenteric adipose tissue were separated under stereoscope microscope. Transmission electron microscopy and immunofluorescence were used to observe the structure of mesenteric lymphatic vessels. The NF-κB signaling pathway in mesenteric adipose tissue was detected in CD specimens using Western blotting. Electron microscopy showed that the structure of mesenteric lymphatic vessel was discontinuous, and the microstructure of lymphatic endothelial cells appeared ruptured and incomplete. Through an immunofluorescence technique, we found that the surface of lymphatic endothelial cells lacked tight junction protein staining in CD. Also, the expression of claudin-1, occludin, and ZO-1 in the mesenteric lymphatic vessel of htMAT was significantly lower than that of control. These results indicated that the structure of the mesenteric lymphatic vessel in htMAT was mispatterned and ruptured, which could lead to lymph leakage. Leaky lymph factors could stimulate adipose tissue to proliferate. Antigens that leaked into the mesenteric adipose tissue could effectively elicit an immune response. The levels of cytokines (TNF-a, IL-1β, IL-6) was increased in the htMAT of CD patients by activated NF-κB signaling pathway. Our findings demonstrated that the hypertrophy of mesenteric adipose tissue may result from mispatterned and ruptured lymphatic vessels. Alteration of mesenteric adipose tissue was associated with activated NF-κB signaling pathway. This study enhances support for elucidating the importance of mesenteric lymphatic vessels and adipose tissue in CD.

Abstract 516: Pharmacological Inhibition of Phosphatase and Tensin Homolog Ameliorates Adipose Tissue Inflammation and Increases Splenic Regulatory B and T Cells in Rats With Metabolic Syndrome

Objectives: B cells have emerged as a critical player in innate and adaptive immune responses. However, little is known about the role of B cells in obesity- and/or stress-induced immune responses. We previously reported that restraint stress exacerbates cardiac and adipose tissue pathology via β-adrenergic signaling in rats with metabolic syndrome (MetS). Phosphatidylinositol 3’-kinase (PI3K)/Akt pathway regulates interleukin-10 production by B cells. Phosphatase and tensin homolog (PTEN) is a lipid/protein phosphatase that can negatively regulate PI3K/Akt pathway. To identify the possible role of PI3K signaling in stress-induced immune responses in metabolic disorders, we now examined the effects of restraint stress and PTEN inhibition on B and T cell subsets in rats with MetS. Methods: We used DahlS.Z- Lepr fa / Lepr fa (DS/obese) rats, derived from a cross between Dahl salt-sensitive and Zucker rats, as an animal model of MetS. Rats were exposed to restraint stress (restraint cage, 2 h/day) for 2 wk from 9 wk of age with or without daily administration of the PTEN inhibitor bisperoxovanadium-pic [bpV(pic), 0.2 mg/kg, i.p.]. Age-matched homozygous lean littermates of DS/obese rats (DahlS.Z- Lepr + / Lepr + rats) served as controls. Results: Treatment with bpV (pic) attenuated hypertension in DS/obese rats under restraint stress. This agent also reduced subcutaneous fat mass and alleviated adipocyte hypertrophy and inflammation in subcutaneous adipose tissue as well as tended to suppress epididymal adipose tissue inflammation in such rats. Flow cytometric analysis showed that regulatory B (Breg) cells were increased and B-1 cells, which attenuate inflammation and insulin resistance, tended to be increased by bpV (pic) in the spleen of DS/obese rats subjected to restrain stress. In addition, bpV (pic) treatment led to an increase in splenic regulatory T (Treg) cells and downregulation of CD8 + T cells in epididymal adipose tissue of stressed rats. Conclusions: PTEN inhibition with bpV (pic) attenuated subcutaneous adipose tissue inflammation as well as increased splenic Breg and Treg cells in DS/obese rats under restraint stress. Pharmacological inhibition of negative regulator of PI3K may represent a therapeutic approach for the treatment of MetS.

FGF21 gene therapy as treatment for obesity and insulin resistance

Prevalence of type 2 diabetes (T2D) and obesity is increasing worldwide. Currently available therapies are not suited for all patients in the heterogeneous obese/T2D population, hence the need for novel treatments. Fibroblast growth factor 21 (FGF21) is considered a promising therapeutic agent for T2D/obesity. Native FGF21 has, however, poor pharmacokinetic properties, making gene therapy an attractive strategy to achieve sustained circulating levels of this protein. Here, adeno‐associated viral vectors (AAV) were used to genetically engineer liver, adipose tissue, or skeletal muscle to secrete FGF21. Treatment of animals under long‐term high‐fat diet feeding or of ob/ob mice resulted in marked reductions in body weight, adipose tissue hypertrophy and inflammation, hepatic steatosis, inflammation and fibrosis, and insulin resistance for > 1 year. This therapeutic effect was achieved in the absence of side effects despite continuously elevated serum FGF21. Furthermore, FGF21 overproduction in healthy animals fed a standard diet prevented the increase in weight and insulin resistance associated with aging. Our study underscores the potential of FGF21 gene therapy to treat obesity, insulin resistance, and T2D.

Extra-Virgin Olive Oil with Natural Phenolic Content Exerts an Anti-Inflammatory Effect in Adipose Tissue and Attenuates the Severity of Atherosclerotic Lesions in Ldlr-/-.Leiden Mice.

The present study investigates the effect of olive oils with different phenolic content in high-fat diets (HFDs) on hypertrophy and inflammation in adipose tissue and associated atherosclerosis, in the context of obesity. Ldlr-/-.Leiden mice were fed three different HFDs for 32 weeks and were compared with mice fed the standard low-fat diet (LFD). The different fats provided in the HFDs were lard (HFD-L), extra-virgin olive oil (EVOO; 79mg kg-1 of phenolic compounds, HFD-EVOO), or EVOO rich in phenolic compounds (OL, 444mg kg-1 of phenolic compounds, HFD-OL). All HFD-fed mice became obese, but only HFD-L-induced adipocyte hypertrophy. HFD-EVOO mice exhibited the greatest levels of Adiponectin in adipose tissue and presented atherosclerotic lesions similar to the LFD group, with a very low count of monocyte/macrophage compared with HFD-L and HFD-OL mice. Enrichment of the phenolic content of olive oil reduced the secretion of nitrites/nitrates in the aorta, but atherosclerosis was not attenuated in HFD-OL mice compared to other HFD mice. Consumption of olive oil with a natural content of phenolic compounds attenuates adipose tissue hypertrophy and inflammation and exerts antiatherosclerotic effects in mice. A higher phenolic content of olive oil did not provide further benefits in the prevention of atherosclerosis.

Dietary sucrose regulates the expression of the Cd36 gene in hepatic tissue of rats with obesity and Non Alcoholic Fatty Liver Disease (NAFLD).

To evaluate the mRNA expression levels of Cd36 in adipose and hepatic tissues, in rats with NAFLD after the consumption of sucrose for 10 and 20 weeks. Twenty Wistar rats, all nearly 21 days old were divided into two experimental groups (NAFLD-10 and NAFLD-20), that received a standard diet (2014 Teklad Global) plus 30% sucrose in their drinking water for 10 and 20 weeks and the control groups (C Groups). Variables such as body weight, food intakes, and serum parameters were measured. Adipose and hepatic tissues were extirpated; some tissue was preserved in formalin and some at -70 °C until analysis. Histological analysis was carried out, and the Cd36 mRNA expression levels were determined. The rats in the NAFLD-10 and NAFLD-20 groups showed a significative increase in abdominal fat, triglycerides, free fatty acids, insulin, AST, ALT, uric acid and HOMA index; as well as changes in the cellular dynamics in adipose tissue, (adipocytes hypertrophic: >1500 µm2) with respect to the control groups (P<0.05). The histological analysis showed development of mild portal hepatitis in rats of the NAFLD-10 group and grade 1 hepatic steatosis with mild portal inflammation in rats of the NAFLD-20 group. Finally, Cd36 mRNA expression levels were significantly increased in hepatic tissue after 10 (1.5-fold) and 20 (3.5-fold) weeks of sucrose ingestion (P<0.05). mRNA expression is a molecular mechanism involved in the development of NAFLD associated with obesity in rats consuming sucrose. However, there was increased Cd36 mRNA expression only in hepatic tissue while in hypertrophic adipose tissue mRNA levels remained unchanged.

Alpha-syntrophin deficient mice are protected from adipocyte hypertrophy and ectopic triglyceride deposition in obesity

Alpha-syntrophin (SNTA) is a molecular adapter protein which is expressed in adipocytes. Knock-down of SNTA in 3T3-L1 preadipocytes increases cell proliferation, and differentiated adipocytes display small lipid droplets. These effects are both characteristics of healthy adipose tissue growth which is associated with metabolic improvements in obesity. To evaluate a role of SNTA in adipose tissue morphology and obesity associated metabolic dysfunction, SNTA deficient mice were fed a standard chow or a high fat diet. Mice deficient of SNTA had less fat mass and smaller adipocytes in obesity when compared to control animals. Accordingly, these animals did not develop liver steatosis and did not store excess triglycerides in skeletal muscle upon high fat diet feeding. SNTA−/− animals were protected from hyperinsulinemia and hepatic insulin resistance. Of note, body-weight, food uptake, and serum lipids were normal in the SNTA null mice. SNTA was induced in adipose tissues but not in the liver of diet induced obese and ob/ob mice. In human subcutaneous and visceral fat of seven patients SNTA was similarly expressed and was not associated with body mass index. Current data demonstrate beneficial effects of SNTA deficiency in obesity which is partly attributed to smaller adipocytes and reduced white adipose tissue mass. Higher SNTA protein in fat depots of obese mice may contribute to adipose tissue hypertrophy and ectopic lipid deposition which has to be confirmed in humans.

Changes in Visceral Adipose Tissue Plasma Membrane Lipid Composition in Old Rats Are Associated With Adipocyte Hypertrophy With Aging.

Increased adiposity, through adipocyte hypertrophy, and/or hyperplasia, characterizes aging and obesity. Both are leptin-resistant states, associated with disturbed lipid metabolism, reduced insulin sensitivity and inflammation. Nevertheless, fat tissue dysfunction appears earlier in obesity than in normal aging. In contrast, lipodystrophy is accompanied by diabetes, and improving the fat cell capacity to expand rescues the diabetic phenotype. Fat tissue dysfunction is extensively studied in the diet-induced obesity, but remains relatively neglected in the aging-associated obesity. In the Wistar rat, as occurs in humans, early or middle aging is accompanied by an increase in adiposity. Using this experimental model, we describe the molecular mechanisms contributing to the white adipose tissue (WAT) hypertrophy. WAT from middle-old age rats is characterized by decreased basal lipogenesis and lipolysis, increased esterification, as demonstrated by the higher TAG and cholesterol content in visceral WAT, and the maintenance of total ceramide levels within normal values. In addition, we describe alterations in the adipose tissue plasma membrane lipid composition, as increased total ether-phosphatidylcholine, sphingomyelin, and free cholesterol levels that favor an enlarged fat cell size with aging. All these metabolic changes may be regarded as a survival advantage that prevents the aged rats from becoming overtly diabetic.

Activation of the sympathetic nervous system suppresses mouse white adipose tissue hyperplasia through the β1 adrenergic receptor.

Adipose tissue (AT) expands via both hypertrophy and hyperplasia during the development of obesity. While AT hypertrophy involves the increase in size of existing adipocytes, hyperplasia is the process of creating new adipocytes from the pool of adipocyte precursor cells (APCs), which includes adipocyte progenitor cells and preadipocytes. Prior studies have implicated a role of the sympathetic nervous system (SNS) in regulation of hyperplasia in white adipose tissue (WAT). Here, we aimed to determine the mechanisms underlying SNS regulation of APC proliferation in mouse WAT. Using flow cytometry with antibodies against various cell surface markers, along with an intracellular marker of proliferation (Ki67), we quantitated the percentages and proliferative status of adipocyte progenitor cells and preadipocytes in the stromal vascular fraction (SVF) of WAT. In vivo SNS activation through cold exposure, as well as in vitro adrenergic stimulation via exposure to the canonical SNS neurotransmitter norepinephrine (NE), inhibited preadipocyte proliferation. Pretreatment with propranolol, a β1‐ and β2‐adrenergic receptor (AR) antagonist, trended toward rescuing the inhibitory effects of NE in primary cell culture. The selective β1‐AR agonist dobutamine diminished preadipocyte proliferation both in vivo and in vitro, whereas the selective β2‐AR agonist, salbutamol, promoted proliferation in vitro, suggesting that the β1‐AR may mediate the inhibitory effect of NE on preadipocyte proliferation. Taken together, we conclude that SNS activation suppresses preadipocyte proliferation via activation of the β1 AR in WAT.

Mulberry extract protects from diet‐induced obesity in association with modulation of gut microbiota in mice

Mulberry, a natural source of flavonoids, phenolics and anthocyanins, has been widely used in edible food and medicine due to its pharmacological effect. Growing evidence indicates that gut microbiota contributes to obesity, type II diabetes and many other related metabolic disorders. The present study was designed to evaluate the influence of the mulberry water extract (ME) on high‐fat diet induced obesity and determine whether the beneficial effects of ME are associated with the modulation of gut microbiota. Forty‐five male C57BL/6J mice were divided into three groups and fed with low‐fat diet, high‐fat diet or high‐fat diet plus ME administration of 300 mg/kg/day for 15 weeks. 16S rDNA sequencing was performed to analyze the composition of gut microbiota. Our results showed that dietary ME reduced HFD‐induced body weight gain and ameliorated adipose tissue hypertrophy and insulin resistance. Moreover, metagenomic analysis indicated that ME supplement significantly changed the ratio of Firmicutes and Bacteroidetes at the phylum level.In conclusion, ME protects from diet‐induced obesity and its related metabolic disorders, which is associated with the modulation of gut microbiota in mice. These findings suggested a dietary choice of mulberry in the nutrition therapy of obesity and its metabolic disorders.Support or Funding InformationNational Natural Science Foundation of China (Grant No. 31701031) China Postdoctoral Science Foundation (Grant No. 2016M601006)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Synergistic Role Among Adipose Tissue Hypertrophy, Dyslipidemia, and Systemic Inflammation in the Development of Atherosclerosis

Recent experimental and clinical evidence has suggested a synergistic causal role among adipose tissue hypertrophy, dyslipidemia, and systemic inflammation in the development and instability of the atherosclerotic plaque. Here, we summarize some of the most recent findings regarding the role of whi te adipose tissue hypertrophy in the development of dyslipidemia and chronic low-grade systemic inflammation. We also review the contribution of dyslipidemia in releasing free-fatty acids, cholesterol, and oxidized low-density lipoproteins as metabolic ligands able to trigger inflammatory signal pathways in macrophages via pattern recognition receptor (PRR) activation. Finally, we discuss the possible mechanisms through which dyslipidemia-related metabolic ligands and chronic low-grade systemic inflammation are capable of inducing macrophage activation, which in turn is involved in mediating instability and rupture of the atherosclerotic plaque. A better understanding of the inflammatory mechanisms contributing to atherosclerosis may help to identify potential molecular targets to decrease the cardiovascular risk in patients by using anti-inflammatory therapies and PRR blockers.

Liposuction Treatment of Lymphedema.

In the Western world, lymphedema most commonly occurs following treatment of cancer. Limb reductions have been reported utilizing various conservative therapies including manual lymph and pressure therapy, as well as by microsurgical reconstruction involving lymphovenous shunts and transplantation of lymph vessels or nodes. Failure of these conservative and surgical treatments to provide complete reduction in patients with long-standing pronounced lymphedema is due to the persistence of excess newly formed subcutaneous adipose tissue in response to slow or absent lymph flow, which is not removed in patients with chronic non-pitting lymphedema. Traditional surgical regimes utilizing bridging procedures, total excision with skin grafting, or reduction plasty seldom achieved acceptable cosmetic and functional results. Liposuction removes the hypertrophied adipose tissue and is a prerequisite to achieve complete reduction, and this reduction is maintained long-term through constant (24 h) use of compression garments postoperatively. This article describes the techniques and evidence basis for the use of liposuction for treatment of lymphedema.

Effect of hypoxia on caveolae-related protein expression and insulin signaling in adipocytes.

Obesity is characterized by hypertrophy and hyperplasia of adipose tissue, which have been related to the development of hypoxia and insulin resistance. On the other hand, caveolin-1 (Cav-1), one of the main proteins of caveolae, promotes insulin receptor (IR) phosphorylation and the subsequent activation of insulin signaling. In this work we investigated the effect of hypoxia on Cav-1 regulation and the status of insulin signaling in 3T3-L1 adipocytes. Our results showed that hypoxia inhibited adipogenesis and insulin signaling in adipocytes. Furthermore, 48 h of hypoxia reduced insulin-induced glucose uptake while increased basal glucose uptake. This result was consistent with the upregulation of glucose transporter GLUT1 and the downregulation of GLUT4, which also showed defective translocation to plasma membrane when adipocytes were stimulated with insulin. In addition, the expression of caveolae-related proteins was reduced by hypoxia and chromatin immunoprecipitation assay demonstrated that Cav-1 transcription was directly regulated by HIF-1. These results strengthen the role of caveolae in insulin signaling and help to explain adipocyte response to hypoxia.

Anti-Inflammatory and Anti-Obesity Properties of Food Bioactive Components: Effects on Adipose Tissue.

Obesity is an epidemic and costly disease affecting 13% of the adult population worldwide. Obesity is associated with adipose tissue hypertrophy and hyperplasia, as well as pathologic endocrine alterations of adipose tissue including local and chronic systemic low-grade inflammation. Moreover, this inflammation is a risk factor for both metabolic syndrome (MetS) and insulin resistance. Basic and clinical studies demonstrate that foods containing bioactive compounds are capable of preventing both obesity and adipose tissue inflammation, improving obesity-associated MetS in human subjects and animal models of obesity. In this review, we discuss the anti-obesity and anti-inflammatory protective effects of some bioactive polyphenols of plant origin and omega-3 polyunsaturated fatty acids, available for the customers worldwide from commonly used foods and/or as components of commercial food supplements. We review how these bioactive compounds modulate cell signaling including through the nuclear factor-κB, adenosine monophosphate-activated protein kinase, mitogen-activated protein kinase, toll-like receptors, and G-protein coupled receptor 120 intracellular signaling pathways and improve the balance of pro- and anti-inflammatory mediators secreted by adipose tissue and subsequently lower systemic inflammation and risk for metabolic diseases.

MicroRNAs-361-5p and miR-574-5p associate with human adipose morphology and regulate EBF1 expression in white adipose tissue.

Reduced adipose expression of the transcription factor Early B cell factor 1 (EBF1) is linked to white adipose tissue (WAT) hypertrophy. We aimed to identify microRNAs (miRNAs) associated with WAT hypertrophy and EBF1 regulation. We mapped WAT miRNA expression from 26 non-obese women discordant in WAT morphology and determined EBF1 activity in the non-obese and 30 obese women. Expression of 15 miRNAs was higher in hypertrophy and 10 were predicted to target EBF1. Binding of miR-365-5p/miR-574-5p were validated with 3'-UTR assay. Overexpression of miR-365-5p or miR-574-5p reduced EBF1 while inhibition of miR-574 increased EBF1 expression in human adipocytes invitro. Additive effects on EBF1 were observed when concomitantly overexpressing both miRNAs. EBF1 targets were affected by over expression/inhibition of either miRNAs. Finally, miR-365-5p/miR-574-5p expression in 56 individuals correlated significantly with EBF1 activity. Our results suggest that miR-365-5p and miR-574-5p may be linked to WAT hypertrophy via effects on EBF1 expression.

Inactivation of SPAK kinase reduces body weight gain in mice fed a high-fat diet by improving energy expenditure and insulin sensitivity.

The STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) controls the activity of the electroneutral cation-chloride cotransporters (SLC12 family) and thus physiological processes such as modulation of cell volume, intracellular chloride concentration [Cl-]i, and transepithelial salt transport. Modulation of SPAK kinase activity may have an impact on hypertension and obesity, as STK39, the gene encoding SPAK, has been suggested as a hypertension and obesity susceptibility gene. In fact, the absence of SPAK activity in mice in which the activating threonine in the T loop was substituted by alanine (SPAK-KI mice) is associated with decreased blood pressure; however its consequences in metabolism have not been explored. Here, we fed wild-type and homozygous SPAK-KI mice a high-fat diet for 17 wk to evaluate weight gain, circulating substrates and hormones, energy expenditure, glucose tolerance, and insulin sensitivity. SPAK-KI mice exhibit resistance to HFD-induced obesity and hepatic steatosis associated with increased energy expenditure, higher thermogenic activity in brown adipose tissue, increased mitochondrial activity in skeletal muscle, and reduced white adipose tissue hypertrophy mediated by augmented whole body insulin sensitivity and glucose tolerance. Our data reveal a previously unrecognized role for the SPAK kinase in the regulation of energy balance, thermogenesis, and insulin sensitivity, suggesting that this kinase could be a new drug target for the treatment of obesity and the metabolic syndrome.

Epigenetic modifications of the Zfp/ZNF423 gene control murine adipogenic commitment and are dysregulated in human hypertrophic obesity

Aims/hypothesisSubcutaneous adipocyte hypertrophy is associated with insulin resistance and increased risk of type 2 diabetes, and predicts its future development independent of obesity. In humans, subcutaneous adipose tissue hypertrophy is a consequence of impaired adipocyte precursor cell recruitment into the adipogenic pathway rather than a lack of precursor cells. The zinc finger transcription factor known as zinc finger protein (ZFP) 423 has been identified as a major determinant of pre-adipocyte commitment and maintained white adipose cell function. Although its levels do not change during adipogenesis, ectopic expression of Zfp423 in non-adipogenic murine cells is sufficient to activate expression of the gene encoding peroxisome proliferator-activated receptor γ (Pparγ; also known as Pparg) and increase the adipogenic potential of these cells. We investigated whether the Zfp423 gene is under epigenetic regulation and whether this plays a role in the restricted adipogenesis associated with hypertrophic obesity.MethodsMurine 3T3-L1 and NIH-3T3 cells were used as fibroblasts committed and uncommitted to the adipocyte lineage, respectively. Human pre-adipocytes were isolated from the stromal vascular fraction of subcutaneous adipose tissue of 20 lean non-diabetic individuals with a wide adipose cell size range. mRNA levels were measured by quantitative real-time PCR, while methylation levels were analysed by bisulphite sequencing. Chromatin structure was analysed by micrococcal nuclease protection assay, and DNA-methyltransferases were chemically inhibited by 5-azacytidine. Adipocyte differentiation rate was evaluated by Oil Red O staining.ResultsComparison of uncommitted (NIH-3T3) and committed (3T3-L1) adipose precursor cells revealed that Zfp423 expression increased (p < 0.01) in parallel with the ability of the cells to differentiate into mature adipocytes owing to both decreased promoter DNA methylation (p < 0.001) and nucleosome occupancy (nucleosome [NUC] 1 p < 0.01; NUC2 p < 0.001) in the 3T3-L1 compared with NIH-3T3 cells. Interestingly, non-adipogenic epigenetic profiles can be reverted in NIH-3T3 cells as 5-azacytidine treatment increased Zfp423 mRNA levels (p < 0.01), reduced DNA methylation at a specific CpG site (p < 0.01), decreased nucleosome occupancy (NUC1, NUC2: p < 0.001) and induced adipocyte differentiation (p < 0.05). These epigenetic modifications can also be initiated in response to changes in the pre-adipose cell microenvironment, in which bone morphogenetic protein 4 (BMP4) plays a key role. We finally showed that, in human adipocyte precursor cells, impaired epigenetic regulation of zinc nuclear factor (ZNF)423 (the human orthologue of murine Zfp423) was associated with inappropriate subcutaneous adipose cell hypertrophy. As in NIH-3T3 cells, the normal ZNF423 epigenetic profile was rescued by 5-azacytidine exposure.Conclusions/interpretationOur results show that epigenetic events regulate the ability of precursor cells to commit and differentiate into mature adipocytes by modulating ZNF423, and indicate that dysregulation of these mechanisms accompanies subcutaneous adipose tissue hypertrophy in humans.