White Adipose Tissue Samples Research Articles

Human adipose tissue as a major reservoir of cytomegalovirus-reactive T cells.

Cytomegalovirus (CMV) is a common herpesvirus with a high prevalence worldwide. After the acute infection phase, CMV can remain latent in several tissues. CD8 T cells in the lungs and salivary glands mainly control its reactivation control. White adipose tissue (WAT) contains a significant population of memory T cells reactive to viral antigens, but CMV specificity has mainly been studied in mouse WAT. Therefore, we obtained blood, omental WAT (oWAT), subcutaneous WAT (sWAT), and liver samples from 11 obese donors to characterize the human WAT adaptive immune landscape from a phenotypic and immune receptor specificity perspective. We performed high-throughput sequencing of the T cell receptor (TCR) locus to analyze tissue and blood TCR repertoires of the 11 donors. The presence of TCRs specific to CMV epitopes was tested through ELISpot assays. Moreover, phenotypic characterization of T cells was carried out through flow cytometry. High-throughput sequencing analyses revealed that tissue TCR repertoires in oWAT, sWAT, and liver samples were less diverse and dominated by hyperexpanded clones when compared to blood samples. Additionally, we predicted the presence of TCRs specific to viral epitopes, particularly from CMV, which was confirmed by ELISpot assays. Remarkably, we found that oWAT has a higher proportion of CMV-reactive T cells than blood or sWAT. Finally, flow cytometry analyses indicated that most WAT-infiltrated lymphocytes were tissue-resident effector memory CD8 T cells. Overall, these findings postulate human oWAT as a major reservoir of CMV-specific T cells, presumably for latent viral reactivation control. This study enhances our understanding of the adaptive immune response in human WAT and highlights its potential role in antiviral defense.

Impact of short and long exposure to cafeteria diet on food intake and white adipose tissue lipolysis mediated by glucagon-like peptide 1 receptor.

The modern food environment facilitates excessive calorie intake, a major driver of obesity. Glucagon-like peptide 1 (GLP1) is a neuroendocrine peptide that has been the basis for developing new pharmacotherapies against obesity. The GLP1 receptor (GLP1R) is expressed in central and peripheral tissues, and activation of GLP1R reduces food intake, increases the expression of thermogenic proteins in brown adipose tissue (BAT), and enhances lipolysis in white adipose tissue (WAT). Obesity decreases the efficiency of GLP1R agonists in reducing food intake and body weight. Still, whether palatable food intake before or during the early development of obesity reduces the effects of GLP1R agonists on food intake and adipose tissue metabolism remains undetermined. Further, whether GLP1R expressed in WAT contributes to these effects is unclear. Food intake, expression of thermogenic BAT proteins, and WAT lipolysis were measured after central or peripheral administration of Exendin-4 (EX4), a GLP1R agonist, to mice under intermittent-short exposure to CAF diet (3 h/d for 8 days) or a longer-continuous exposure to CAF diet (24 h/d for 15 days). Ex-vivo lipolysis was measured after EX4 exposure to WAT samples from mice fed CAF or control diet for 12 weeks. . During intermittent-short exposure to CAF diet (3 h/d for 8 days), third ventricle injection (ICV) and intra-peritoneal administration of EX4 reduced palatable food intake. Yet, during a longer-continuous exposure to CAF diet (24 h/d for 15 days), only ICV EX4 administration reduced food intake and body weight. However, this exposure to CAF diet blocked the increase in uncoupling protein 1 (UCP1) caused by ICV EX4 administration in mice fed control diet. Finally, GLP1R expression in WAT was minimal, and EX4 failed to increase lipolysis ex-vivo in WAT tissue samples from mice fed CAF or control diet for 12 weeks. . Exposure to a CAF diet during the early stages of obesity reduces the effects of peripheral and central GLP1R agonists, and WAT does not express a functional GLP1 receptor. These data support that exposure to the obesogenic food environment, without the development or manifestation of obesity, can alter the response to GLP1R agonists. .

The Role of IL-13 and IL-4 in Adipose Tissue Fibrosis

White adipose tissue (WAT) fibrosis, characterized by an excess of extracellular (ECM) matrix components, is strongly associated with WAT inflammation and dysfunction due to obesity. Interleukin (IL)-13 and IL-4 were recently identified as critical mediators in the pathogenesis of fibrotic diseases. However, their role in WAT fibrosis is still ill-defined. We therefore established an ex vivo WAT organotypic culture system and demonstrated an upregulation of fibrosis-related genes and an increase of α-smooth muscle actin (αSMA) and fibronectin abundance upon dose-dependent stimulation with IL-13/IL-4. These fibrotic effects were lost in WAT lacking il4ra, which encodes for the underlying receptor controlling this process. Adipose tissue macrophages were found to play a key role in mediating IL-13/IL-4 effects in WAT fibrosis as their depletion through clodronate dramatically decreased the fibrotic phenotype. IL-4-induced WAT fibrosis was partly confirmed in mice injected intraperitoneally with IL-4. Furthermore, gene correlation analyses of human WAT samples revealed a strong positive correlation of fibrosis markers with IL-13/IL-4 receptors, whereas IL13 and IL4 correlations failed to confirm this association. In conclusion, IL-13 and IL-4 can induce WAT fibrosis ex vivo and partly in vivo, but their role in human WAT remains to be further elucidated.

Co-expression analysis of lncRNA and mRNA identifies potential adipogenesis regulatory non-coding RNAs involved in the transgenerational effects of tributyltin.

The obesity epidemic is considered a global public health crisis, with an increase in caloric intake, sedentary lifestyles and/or genetic predispositions as contributing factors. Although the positive energy balance is one of the most significant causes of obesity, recent research has linked early exposure to Endocrine-Disrupting Chemicals (EDCs) such as the obesogen tributyltin (TBT) to the disease epidemic. In addition to their actions on the hormonal profile, EDCs can induce long-term changes in gene expression, possibly due to changes in epigenetic patterns. Long non-coding RNAs (lncRNAs) are epigenetic mediators that play important regulatory roles in several biological processes, through regulation of gene transcription and/or translation. In this study, we explored the differential expression of lncRNAs in gonadal white adipose tissue samples from adult male C57BL/6J F4 generation, female C57BL/6J offspring exposed (F0 generation) to 50 nM TBT or 0.1% DMSO (control of vehicle) via drinking water provided during pregnancy and lactation, analyzing RNA-seq data from a publicly available dataset (GSE105051). A total of 74 lncRNAs were differentially expressed (DE), 22 were up-regulated and 52 were down-regulated in the group whose F4 ancestor was exposed in utero to 50nM TBT when compared to those exposed to 0.1% DMSO (control). Regulation of DE lncRNAs and their potential partner genes in gonadal white adipose tissue of mice ancestrally exposed to EDC TBT may be related to the control of adipogenesis, as pathway enrichment analyses showed that these gene partners are mainly involved in the metabolism of lipids and glucose and in insulin-related pathways, which are essential for obesity onset and control.

Comprehensive Analysis of circRNA Expression Profiles in Human Brown Adipose Tissue.

Brown adipose tissue (BAT) can rapidly generate heat and improve energy metabolism. Circular RNAs (circRNAs) are cellular endogenous non-coding RNAs, which can regulate the development and progress of different diseases. However, the role of circRNAs in human BAT is not fully understood. Here, we analyzed the differentially expressed circRNAs (DECs) in human BAT, as well as in white adipose tissue (WAT), and identified new biomarkers of BAT. Three human BAT and three human subcutaneous WAT samples were selected, and circRNA microarray was performed. Additionally, quantitative real-time polymerase chain reaction (qRT-PCR) was applied to determine the expression of six circRNAs. Finally, the functional analysis was performed by bioinformatics. Compared to WAT, 152 upregulated circRNAs and 201 downregulated circRNAs were identified in BAT. The DECs were further subjected to GO and KEGG enrichment analysis. Several circRNAs, for example, hsa_circ_0006168, hsa_circ_26337 and hsa_circ_0007507 were found upregulated and hsa_circ_0030162 was found downregulated in human BAT compared to WAT. This study profiles the circRNA expression in human BAT and WAT, and suggests hsa_circ_0006168, hsa_circ_26337, hsa_circ_0007507, and hsa_circ_0030162 as novel biomarkers for human BAT.

The circadian transcription factor ARNTL2 is regulated by weight-loss interventions in human white adipose tissue and inhibits adipogenesis

Misalignment of physiological circadian rhythms promotes obesity which is characterized by white adipose tissue (WAT) expansion. Differentiation of Adipose stem/progenitor cells (ASCs) contributes to WAT increase but the importance of the cellular clock in this process is incompletely understood. In the present study, we reveal the role of the circadian transcription factor Aryl hydrocarbon receptor nuclear translocator-like 2 (ARNTL2) in human ASCs, isolated from subcutaneous (s)WAT samples of patients undergoing routine elective plastic abdominal surgery. We show that circadian synchronization by serum-shock or stimulation with adipogenic stimuli leads to a different expression pattern of ARNTL2 relative to its well-studied paralogue ARNTL1. We demonstrate that ARNTL2 mRNA is downregulated in ASCs upon weight-loss (WL) whereas ARNTL2 protein is rapidly induced in the course of adipogenic differentiation and highly abundant in adipocytes. ARNTL2 protein is maintained in ASCs cooperatively by mechanistic Target of Rapamycin (mTOR) and Mitogen-activated Protein Kinase (MAPK) signalling pathways while ARNTL2 functions as an inhibitor on both circuits, leading to a feedback mechanism. Consistently, ectopic overexpression of ARNTL2 repressed adipogenesis by facilitating the degradation of ARNTL1, inhibition of Kruppel-Like Factor 15 (KLF15) gene expression and down-regulation of the MAPK-CCAAT/enhancer-binding protein β (C/EBPβ) axis. Western blot analysis of sWAT samples from normal-weight, obese and WL donors revealed that ARNTL2 protein was solely elevated by WL compared to ARNTL1 which underscores unique functions of both transcription factors. In conclusion, our study reveals ARNTL2 to be a WL-regulated inhibitor of adipogenesis which might provide opportunities to develop strategies to ameliorate obesity.

Behavioral defects and downregulation of hippocampal BDNF and nNOS expression in db/db mice did not improved by chronic TGF-β2 treatment.

Epidemiological evidence suggests that there is a link between diabetes and mood disorders, such as depression and anxiety. Although peripheral or central inflammation may explain this link, the molecular mechanisms are not fully understood and few effective treatments for diabetes or mood disorders are available. In the present study, we aimed to determine whether transforming growth factor (TGF)-β2, an anti-inflammatory substance, might represent a potential therapeutic agent for diabetes-related mood behaviors. TGF-β2 expression in the hippocampus is affected by anxiolytic drugs and stress exposure, it is able to cross the blood-brain barrier, and it is as an exercise-induced physiological adipokine that regulates glucose homeostasis. Therefore, we hypothesized that a chronic TGF-β2 infusion would ameliorate diabetes-related glucose intolerance and mood dysregulation. To determine the effects of the chronic administration of TGF-β2 on diabetes, we implanted osmotic pumps containing TGF-β2 into type 2 diabetic mice (db/db mice), and age-matched non-diabetic control wild type mice and db/db mice were infused with vehicle (PBS), for 12 consecutive days. To assess anxiety-like behaviors and glucose homeostasis, the mice underwent elevated plus maze testing and intraperitoneal glucose tolerance testing. Hippocampal and perigonadal visceral white adipose tissue perigonadal white adipose tissue samples were obtained 12 days later. Contrary to our hypothesis, TGF-β2 infusion had no effect on diabetes-related glucose intolerance or diabetes-related behavioral defects, such as inactivity. In db/db mice, the expression of inflammatory markers was high in pgWAT, but not in the hippocampus, and the former was ameliorated by TGF-β2 infusion. The expression of brain-derived neurotrophic factor and neuronal nitric oxide synthase, important regulators of anxiety-like behaviors, was low in db/db mice, but TGF-β2 infusion did not affect their expression. We conclude that although TGF-β2 reduces the expression of pro-inflammatory markers in the adipose tissue of diabetic mice, it does not ameliorate their obesity or mood dysregulation.

The effects of taurine supplementation on obesity and browning of white adipose tissue in high-fat diet-fed mice

Background: In recent years, a new type of adipose tissue (beige adipose tissue) has been mentioned, unlike white adipose tissue (WAT) and brown adipose tissue (BAT). Beige cells are capable of thermogenesis like BAT. In response to various agents, beige cells can develop within WAT through a process called “browning.” Therefore, the prevention of obesity and related diseases by providing WAT browning with new potential agents has been extensively studied in recent years. Taurine has many physiological functions in the body and has beneficial effects on obesity and related metabolic disorders. For this reason, we aimed to investigate whether taurine supplementation has effects on browning of WAT and attenuating obesity. Methods: Thirty-two male C57BL/6 mice were used for the study. Mice were divided into 4 groups as control, control + taurine, high fat diet (HFD) and HFD + taurine, and fed for 20 weeks. Taurine was given in drinking water (5%). Epididymal WAT samples were obtained from mice and RNA was extracted from these tissues. Expression levels of FLCN, mTOR, TFE3, PGC-1α, PGC1-1β, AMPK, S6K and UCP1 genes were measured by real-time PCR. Results: Taurine supplementation reduced HFD-induced obesity. No UCP1 expression was detected in any of the groups studied. Any of the gene expressions were not significantly different between HFD and HFD + taurine groups. Reduced PGC-1α and PGC-1β expressions were observed in both HFD and HFD + taurine groups. Conclusions: Taurine reduced the obesity in HFD fed mice, but had no effect on browning of epididymal WAT in this study.

Investigation of obesogenic effects of hexachlorobenzene, DDT and DDE in male rats

Obesity has become a very important public health problem and is increasing globally. Genetics, individual and environmental factors play roles in the etiology of this complex disorder. Recently, several environmental pollutants have been suggested to have obesogenic activities. Peroxisome proliferator activating receptor gamma (PPARγ), uncoupling protein-1 (UCP1) and their expression in white adipose tissue (WAT) and brown adipose tissue (BAT) play key roles in adipogenesis. UCP3 and irisin were reported to play roles in non-shivering thermogenesis. Our primary aim was to investigate obesogenic effects of hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) in rats. In addition, thermoregulatory effects of HCB, DDT and DDE were also investigated by analyzing the levels of Ucp3 and irisin. Thirty-two adult male Sprague-Dawley rats were randomly divided into four groups as control, HCB, DDT and DDE. Animals were administered with organochlorine pesticides (OCPs; 5 mg/kg bw) by oral gavage every other day for five weeks. At the end of the experimental period, the animals were sacrificed, BAT and WAT samples were collected to analyze Pparγ, Ucp1 and Ucp3 levels. Moreover, skeletal muscle samples were collected to examine Ucp3 and irisin levels. Serum glucose, cholesterol and triglyceride levels were also determined. Body weight and core temperature of the animals were not significantly affected by any of the OCP administration. Serum glucose, cholesterol and triglyceride levels were similar among the experimental groups. Pparγ expression was significantly elevated by HCB administration only in WAT (p < 0.05). On the other hand, both Pparγ and Ucp1 expressions were diminished in WAT and BAT (p < 0.01) by DDT treatment, while in WAT, DDE significantly decreased Pparγ expression without altering its expression in BAT (p < 0.001). Ucp3 and irisin levels in skeletal muscle were not altered. Our findings show that both DDT and DDE reduce the browning of WAT by suppressing white adipocytes and thus may have obesogenic activity in male rats without altering thermoregulation. In addition, HCB, DDT and DDE-induced alterations in expression of Pparγ and Ucp1 in WAT implicates differential regulation of adipogenic processes.

PPAR-γ integrates obesity and adipocyte clock through epigenetic regulation of Bmal1.

While growing evidence suggests that circadian clock and obesity are intertwined, the underlying mechanism is poorly understood. Here, we investigate how circadian clock is linked to obesity.Methods: Metabolomics profiling of WAT (white adipose tissue) samples was performed to identify the metabolites altered in obese model. mRNA levels were analyzed by qPCR assays. Proteins were detected by immunoblotting, immunofluorescence and ELISA. ChIP and luciferase reporter assays were used to investigate epigenetic and transcriptional regulation.Results: Obesity causes perturbance of circadian clock in WAT in mice and humans, particularly, BMAL1 is markedly reduced. Metabolomic analysis reveals reduced glutamine and methionine in obese WAT. Glutamine metabolism contributes to production of acetyl-CoA, whereas methionine metabolism generates S-adenosyl methionine (SAM). Acetyl-CoA and SAM are the substrates for histone acetylation and methylation, respectively. Reduced glutamine and methionine in obese WAT are associated with decreased H3K27ac and H3K4me3 at Bmal1 promoter. Consistently, glutamine or methionine administration in vitro and in vivo increases H3K27ac or H3K4me3, promoting Bmal1 transcription and expression. A screen of transport and metabolic genes identifies downregulation of the uptake transporter SLC1A5 as a cause of reduced glutamine or methionine in obese WAT. Moreover, we observe impaired expression of PPAR-γ in obese WAT. PPAR-γ trans-activates Slc1a5 via direct binding to a response element in promoter.Conclusion: Impaired PPAR-γ in obesity provokes downregulation of SLC1A5 and reductions in adipocyte uptake of glutamine and methionine (two epigenetic modulators), leading to disruption of Bmal1. Therefore, PPAR-γ integrates obesity and adipocyte clock, promoting a vicious cycle between circadian disruption and obesity development.

Changes in white adipose tissue gene expression in a randomized control trial of dieting obese men with lowered serum testosterone alone or in combination with testosterone treatment.

The aim of this study was to determine early weight loss-associated changes in subcutaneous abdominal white adipose tissue (WAT) gene expression in obese men with lowered serum testosterone by RNA next-generation sequencing. Fourteen men, mean age (IQR) 51.6 years (43.4-54.5), BMI 38.3 kg/m2 (34.6-40.8) and total testosterone 8.4 nmol/L (7.5-9.5) provided subcutaneous WAT samples at baseline and after 2 weeks of a very low energy diet. Body weight loss was similar in participants receiving testosterone (n = 6), -5.27 kg [95% CI -6.17; -4.26], and placebo (n = 8), -4.57 kg [95% CI -6.10; -3.55], p = 0.86. In placebo-treated men, of the 14,410 genes expressed in subcutaneous WAT, four genes, Angiopoietin-like 4, Semaphorin 3 G, Neuropilin 2 and Angiopoietin 4, were upregulated (adjusted false discovery rate P < 0.05). In an exploratory analysis comparing men receiving testosterone and placebo, the most-upregulated gene in the testosterone group (exploratory p < 0.0005) was the neuropeptide y receptor 2. In obese men, dieting is associated with upregulation of WAT-expressed Angiopoietin-like 4, a secreted protein that regulates lipid metabolism, Semaphorin 3 G, a proposed adipocyte differentiation factor and secreted adipokine, and its receptor Neuropilin 2, as well as Angiopoietin 4, a vascular integrity factor. In an exploratory analysis, testosterone was associated with the upregulation of neuropeptide y receptor 2, a receptor involved in appetite regulation. Further studies are needed to confirm these observations and their potential biological implications. clinicaltrials.gov, Identifier NCT01616732, Registration date: June 8, 2012.

Lipid droplet-size mapping in human adipose tissue using a clinical 3T system.

To develop a methodology for probing lipid droplet sizes with a clinical system based on a diffusion-weighted stimulated echo-prepared turbo spin-echo sequence and to validate the methodology in water-fat emulsions and show its applicability in ex vivo adipose-tissue samples. A diffusion-weighted stimulated echo-prepared preparation was combined with a single-shot turbo spin-echo readout for measurements at different b-values and diffusion times. The droplet size was estimated with an analytical expression, and three fitting approaches were compared: magnitude-based spatial averaging with voxel-wise residual minimization, complex-based spatial averaging with voxel-wise residual minimization, and complex-based spatial averaging with neighborhood-regularized residual minimization. Simulations were performed to characterize the fitting residual landscape and the approaches' noise performance. The applicability was assessed in oil-in-water emulsions in comparison with laser deflection and in ten human white adipose tissue samples in comparison with histology. The fitting residual landscape showed a minimum valley with increasing extent as the droplet size increased. In phantoms, a very good agreement of the mean droplet size was observed between the diffusion-weighted MRI-based and the laser deflection measurements, showing the best performance with complex-based spatial averaging with neighborhood-regularized residual minimization processing (R2 /P: 0.971/0.014). In the human adipose-tissue samples, complex-based spatial averaging with neighborhood-regularized residual minimization processing showed a significant correlation (R2 /P: 0.531/0.017) compared with histology. The proposed acquisition and parameter-estimation methodology was able to probe restricted diffusion effects in lipid droplets. The methodology was validated using phantoms, and its feasibility in measuring an apparent lipid droplet size was demonstrated ex vivo in white adipose tissue.

Raman Spectroscopy for Adipose Tissue Assessment in Rat Models of Obesity and Type 1 Diabetes.

Adipose tissue presents structural and functional changes in obesity and type 1 diabetes mellitus (T1DM). In obesity, the size and number of adipocytes and adipokine secretion increases. In T1DM, a loss of adipose tissue suggests changes in the metabolic activity of this tissue. A significant challenge is to find alternative noninvasive methods to evaluate molecular changes in adipose tissue related to obesity and T1DM. Recently, Raman spectroscopy and chemometrics techniques have emerged as a tool for biological tissue analysis. In this work, we propose the use of Raman spectroscopy to characterize spectral differences in adipose tissue from different rat groups (control, obese, and T1DM). The Raman spectra were analyzed using direct band analysis, ratiometric analysis, and chemometric methods (principal component analysis (PCA) and support vector machines (SVMs)). We found that the Raman spectra of obese rats showed significant spectral differences compared to control and diabetic groups related to fatty acids Raman bands. Also, the obese group has a significant decrease in the degree of unsaturation of lipids. The PCA-SVM models showed classification performance ranging from 71.43% to 71.79% accuracy for brown and white adipose tissue samples, respectively. In conclusion, the results demonstrate that Raman spectroscopy can be used as a nondestructive method to assess adipose tissue according to a metabolic condition.

Repetitive Intermittent Hyperglycemia Drives the M1 Polarization and Inflammatory Responses in THP-1 Macrophages Through the Mechanism Involving the TLR4-IRF5 Pathway.

Repetitive intermittent hyperglycemia (RIH) is an independent risk factor for complications associated with type-2 diabetes (T2D). Glucose fluctuations commonly occur in T2D patients with poor glycemic control or following intensive therapy. Reducing blood glucose as well as glucose fluctuations is critical to the control of T2D and its macro-/microvascular complications. The interferon regulatory factor (IRF)-5 located downstream of the nutrient sensor toll-like receptor (TLR)-4, is emerging as a key metabolic regulator. It remains unclear how glucose fluctuations may alter the IRF5/TLR4 expression and inflammatory responses in monocytes/macrophages. To investigate this, first, we determined IRF5 gene expression by real-time qRT-PCR in the white adipose tissue samples from 39 T2D and 48 nondiabetic individuals. Next, we cultured THP-1 macrophages in hypo- and hyperglycemic conditions and compared, at the protein and transcription levels, the expressions of IRF5, TLR4, and M1/M2 polarization profile and inflammatory markers against control (normoglycemia). Protein expression was assessed using flow cytometry, ELISA, Western blotting, and/or confocal microscopy. IRF5 silencing was achieved by small interfering RNA (siRNA) transfection. The data show that adipose IRF5 gene expression was higher in T2D than nondiabetic counterparts (p = 0.006), which correlated with glycated hemoglobin (HbA1c) (r = 0.47/p < 0.001), homeostatic model assessment of insulin resistance (HOMA-IR) (r = 0.23/p = 0.03), tumor necrosis factor (TNF)-α (r = 0.56/p < 0.0001), interleukin (IL)-1β (r = 0.40/p = 0.0009), and C-C motif chemokine receptor (CCR)-2 (r = 0.49/p < 0.001) expression. IRF5 expression in macrophages was induced/upregulated (p < 0.05) by hypoglycemia (3 mM/L), persistent hyperglycemia (15 mM/L–25 mM/L), and RIH/glucose fluctuations (3–15 mM/L) as compared to normoglycemia (5 mM/L). RIH/glucose fluctuations also induced M1 polarization and an inflammatory profile (CD11c, IL-1β, TNF-α, IL-6, and monocyte chemoattractant protein (MCP)-1) in macrophages. RIH/glucose fluctuations also drove the expression of matrix metalloproteinase (MMP)-9 (p < 0.001), which is a known marker for cardiovascular complication in T2D patients. Notably, all these changes were counteracted by IRF5 silencing in macrophages. In conclusion, RIH/glucose fluctuations promote the M1 polarization and inflammatory responses in macrophages via the mechanism involving TLR4-IRF5 pathway, which may have significance for metabolic inflammation.

Study on the role of flavonoids derived extract from seed residues of hippophae rhamnoides on high-fat diet induced obese mice

The objective of the paper was to explore the active mechanism underlying the role of flavonoids, which were derived from seed residues of hippophae rhamnoides (Flavonoids from the Seeds of H. rhamnoides L., FSH), in obesity. A total of 50 SPF healthy male C57BL/6 mice were selected and divided into 5 groups (with 10 mice in each group), i.e., the normal control group, the high fat diet control group, the 100 mg/kg FSH group, the 300 mg/kg FSH group, and the rosiglitazone group. The basic biochemical indicators of the mice were detected, and the liver and white adipose tissue samples were collected, stained and analyzed via Western Blot to study the effects of flavonoids on obesity. In the experiment, rosiglitazone was used as a traditional weight-inhibiting drug and its efficacy was compared with that in the FSH groups. It was found that compared with that in the high-fat diet control group, the weight gain of obese mice administered with FSH was slowed, along with reduced levels of serum total cholesterol, plasma glucose, and liver fat accumulation. Meanwhile, it was also discovered that FSH could reduce the expression of PPARγ in liver and white adipose tissues, thus helping to reduce fat accumulation. It was proved that the flavonoids derived from seed residues of hippophae rhamnoides exerted an inhibitory effect on obesity to protect the liver.

Quantification of Fat Concentration and Vascular Response in Brown and White Adipose Tissue of Rats by Spectral CT Imaging.

ObjectiveThe purpose of the study was to non-invasively characterize and discriminate brown adipose tissue (BAT) from white adipose tissue (WAT) in rats using spectral computed tomography (CT) with histological validation.Materials and MethodsA lipid-containing phantom (lipid fractions from 0% to 100%) was imaged with spectral CT. An in vivo, non-enhanced spectral CT scan was performed on 24 rats, and fat concentrations of BAT and WAT were measured. The rats were randomized to receive intraperitoneal treatment with norepinephrine (NE) (n = 12) or saline (n = 12). Non-enhanced and enhanced spectral CT scans were performed after treatment to measure the elevation of iodine in BAT and WAT. The BAT/aorta and WAT/aorta ratios were calculated and compared, after which isolated BAT and WAT samples were subjected to histological and uncoupling protein 1 (UCP1) analyses.ResultsThe ex-vivo phantom study showed excellent linear fit between measured fat concentration and the known gravimetric reference standard (r2 = 0.996). In vivo, BAT had significantly lower fat concentration than WAT (p < 0.001). Compared to the saline group, the iodine concentration of BAT increased significantly (p < 0.001) after injection of NE, while the iodine concentration of WAT only changed slightly. The BAT/aorta ratio also increased significantly after exposure to NE compared to the saline group (p < 0.001). Histological and UCP1 expression analyses supported the spectral CT imaging results.ConclusionThe study consolidates spectral CT as a new approach for non-invasive imaging of BAT and WAT. Quantitative analyses of BAT and WAT by spectral CT revealed different characteristics and pharmacologic activations in the two types of adipose tissue.

Age- and BMI-Associated Expression of Angiogenic Factors in White Adipose Tissue of Children.

The growth of adipose tissue and its vasculature are tightly associated. Angiogenic factors have been linked to obesity, yet little is known about their expression during early childhood. To identify associations of angiogenic factors with characteristics on individual and tissue level, subcutaneous white adipose tissue samples were taken from 45 children aged 0–9 years undergoing elective surgery. We measured the expression of vascular endothelial growth factor A (VEFGA), fibroblast growth factor 1 and 2 (FGF1, FGF2), angiopoietin 1 and 2 (ANGPT1, ANGPT2), TEK receptor tyrosine kinase (TEK), and von Willebrand factor (VWF). In addition, we determined the mean adipocyte size in histologic tissue sections. We found positive correlations of age with FGF1 and FGF2 and a negative correlation with ANGPT2, with pronounced differences in the first two years of life. FGF1, FGF2, and ANGPT1 correlated positively with adipocyte size. Furthermore, we identified a correlation of ANGPT1 and TEK with body mass index-standard deviation score (BMI-SDS), a measure to define childhood obesity. Except for ANGPT2, all angiogenic factors correlated positively with the endothelial marker VWF. In sum, our findings suggest that differences related to BMI-SDS begin early in childhood, and the analyzed angiogenic factors possess distinct roles in adipose tissue biology.

Alternatively Activated Macrophages Drive Browning of White Adipose Tissue in Burns.

The aim of this study was to uncover the mediators and mechanistic events that facilitate the browning of white adipose tissue (WAT) in response to burns. In hypermetabolic patients (eg, burns, cancer), the browning of WAT has presented substantial clinical challenges related to cachexia, atherosclerosis, and poor clinical outcomes. Browning of the adipose tissue has recently been found to induce and sustain hypermetabolism. Although browning appears central in trauma-, burn-, or cancer-induced hypermetabolic catabolism, the mediators are essentially unknown. WAT and blood samples were collected from patients admitted to the Ross Tilley Burn Centre at Sunnybrook Hospital. Wild type, CCR2 KO, and interleukin (IL)-6 KO male mice were purchased from Jax laboratories and subjected to a 30% total body surface area burn injury. WAT and serum collected were analyzed for browning markers, macrophages, and metabolic state via histology, gene expression, and mitochondrial respiration. In the present study, we show that burn-induced browning is associated with an increased macrophage infiltration, with a greater type 2 macrophage profile in the fat of burn patients. Similar to our clinical findings in burn patients, both an increase in macrophage recruitment and a type 2 macrophage profile were also observed in post burn mice. Genetic loss of the chemokine CCR2 responsible for macrophage migration to the adipose impairs burn-induced browning. Mechanistically, we show that macrophages recruited to burn-stressed subcutaneous WAT (sWAT) undergo alternative activation to induce tyrosine hydroxylase expression and catecholamine production mediated by IL-6, factors required for browning of sWAT. Together, our findings uncover macrophages as the key instigators and missing link in trauma-induced browning.

Higher lactate production from glucose in cultured adipose nucleated stromal cells than for rat adipocytes

ABSTRACT White adipose tissue (WAT) nucleated stromal cells (NSC) play important roles in regulation, defense, regeneration and metabolic control. In WAT sites, the proportions and functions of NSC change under diverse physiological or pathologic conditions. We had previously observed the massive anaerobic wasting of glucose to lactate and glycerol in rat epididymal adipocytes. To test site variability, and whether the adipocyte extensive anaerobic metabolism of glucose was found in NSC, we analyzed, in parallel, subcutaneous, mesenteric and epididymal WAT of male adult Wistar rats. Adipocytes and NSC fractions, were isolated, counted and incubated (as well as red blood cells: RBC) with glucose, and their ability to use glucose and produce lactate, glycerol, and free fatty acids was measured. Results were computed taking into account the number of cells present in WAT samples. Cell numbers were found in proportions close to 1:13:100 (respectively, for adipocytes, NSC and RBC) but their volumes followed a reversed pattern: 7,500:10:1. When counting only non-fat cell volumes, the ratios changed dramatically to 100:10:1. RBC contribution to lactate production was practically insignificant. In most samples, NSC produced more lactate than adipocytes did, but only adipocytes secreted glycerol (and fatty acids in smaller amounts). Glucose consumption was also highest in NSC, especially in mesenteric WAT. The heterogeneous NSC showed a practically anaerobic metabolism (like that already observed in adipocytes). Thus, NSC quantitative production of lactate markedly contributed (i.e. more than adipocytes) to WAT global use (wasting) of glucose. We also confirmed that glucose-derived glycerol is exclusively produced by adipocytes.

A Microphysiologic Platform for Human Fat: Sandwiched White Adipose Tissue.

White adipose tissue (WAT) plays a crucial role in regulating weight and everyday health. Still, there are significant limitations to available primary culture models, all of which have failed to faithfully recapitulate the adipose microenvironment or extend WAT viability beyond two weeks. The lack of a reliable primary culture model severely impedes research in WAT metabolism and drug development. To this end we have utilized NIH's standards of a microphysiologic system to develop a novel platform for WAT primary culture called 'SWAT' (sandwiched white adipose tissue). We overcome the natural buoyancy of adipocytes by sandwiching minced WAT clusters between sheets of adipose-derived stromal cells. In this construct, WAT samples are viable over eight weeks in culture. SWAT maintains the intact ECM, cell-to-cell contacts, and physical pressures of in vivo WAT conditions; additionally, SWAT maintains a robust transcriptional profile, sensitivity to exogenous chemical signaling, and whole tissue function. SWAT represents a simple, reproducible, and effective method of primary adipose culture. Potentially, it is a broadly applicable platform for research in WAT physiology, pathophysiology, metabolism, and pharmaceutical development.