Abdominal Subcutaneous White Adipose Tissue Research Articles

Rapid downregulation of DICER is a hallmark of adipose tissue upon high-fat diet feeding

Adipose tissue regulates whole-body energy balance and is crucial for metabolic health. With energy surplus, adipose tissue expands, which may lead to local areas of hypoxia and inflammation, and consequently impair whole-body insulin sensitivity. We report that DICER, a key enzyme for miRNA maturation, is significantly lower in abdominal subcutaneous white adipose tissue of men with obesity compared with men with a lean phenotype. Furthermore, DICER is profoundly downregulated in mouse adipose tissue and liver within the first week on a high-fat diet (HFD), and remains low after prolonged HFD feeding. Downregulation of DICER in mice occurs in both mature adipocytes and stromal vascular cells. Mechanistically, chemically induced hypoxia in vitro shows DICER degradation via interaction with hypoxia-inducible factor 1-α (HIF1α). Moreover, DICER and HIF1α interact in brown adipose tissue post-HFD which may signal for DICER degradation. Finally, RNA sequencing reveals a striking time-dependent downregulation of total miRNA content in mouse subcutaneous adipose tissue after HFD feeding. Collectively, HFD in mice reduces adipose tissue DICER, likely due to hypoxia-induced interaction with HIF1α during tissue expansion, and significantly impacts miRNA content.

Aging human abdominal subcutaneous white adipose tissue at single cell resolution.

White adipose tissue (WAT) is a robust energy storage and endocrine organ critical for maintaining metabolic health as we age. Our aim was to identify cell-specific transcriptional aberrations that occur in WAT with aging. We leveraged full-length snRNA-Seq and histology to characterize the cellular landscape of human abdominal subcutaneous WAT in a prospective cohort of 10 younger (≤30 years) and 10 older individuals (≥65 years) balanced for sex and body mass index (BMI). The older group had greater cholesterol, very-low-density lipoprotein, triglycerides, thyroid stimulating hormone, and aspartate transaminase compared to the younger group (p < 0.05). We highlight that aging WAT is associated with adipocyte hypertrophy, increased proportions of lipid-associated macrophages and mast cells, an upregulation of immune responses linked to fibrosis in pre-adipocyte, adipocyte, and vascular populations, and highlight CXCL14 as a biomarker of these processes. We show that older WAT has elevated levels of senescence marker p16 in adipocytes and identify the adipocyte subpopulation driving this senescence profile. We confirm that these transcriptional and phenotypical changes occur without overt fibrosis and in older individuals that have comparable WAT insulin sensitivity to the younger individuals.

Can Point Shear Wave Elastography be Used as an Indicator of Metabolic Complications in Overweight Children and Adolescents? Evaluation of Subcutaneous Adipose Tissue

This study aims to search the association of obesity, metabolic parameters, and abdominal subcutaneous white adipose tissue (scWAT) stiffness in children and adolescents using ultrasound point shear wave elastography (p-SWE). One hundred and forty overweight or obese children referred to as overweight were included in the study group. Thirty-two lean children, referred to as leans, were included in the control group. In all individuals, scWAT shear wave speed (SWS) was measured with p-SWE. ScWAT stiffness was compared between the two groups. The association of anthropometric, metabolic factors and scWAT stiffness is determined. Weight, body mass index, body mass index-standard deviation score, systolic blood pressure, diastolic blood pressure, alanine aminotransferase, fasting insulin were significantly higher in the overweight group (p&lt;0,05). ScWAT SWS was significantly different between the groups (p=0.006) The median value of scWAT SWS was 1,5 m/s (range; 0.9-3.8), 1.23 m/s (range; 0.7-3.1) for leans and overweight, respectively. In leans, no significant difference was found between boys and girls for scWAT SWS (p=0.094). In overweight, a significant difference was found for scWAT SWS between boys and girls (p=0.022). The scWAT stiffness is lower in overweight than leans. Gender has a pivotal role in scWAT stiffness. If supported with future long-time follow-up studies, p-SWE may be compatible with assessing subcutaneous adipose tissue changes related to obesity and metabolic complications in childhood and adolescence.

Biological Determinants of Metabolic Syndrome in Visceral and Subcutaneous Adipose Tissue from Severely Obese Women.

The metabolic syndrome (MetS) is a cluster of the most dangerous heart attack risk factors: diabetes or raised fasting plasma glucose, abdominal obesity, high cholesterol and high blood pressure. The goal of this study is to compare the state of the main features of obesity-associated white adipose tissue (WAT) dysfunction in 66 women with severe obesity without (MetS−) or with MetS (MetS+). Fat cell area, adipocyte size distribution and histological fibrosis were analysed in visceral (VAT) and abdominal subcutaneous WAT (SAT) in 33 age- and BMI-matched pairs of MetS− and MetS+ subjects. The mRNA expression of 93 genes implicated in obesity-associated WAT dysfunction was analysed by RT-qPCR in both fat depots. MetS+ females showed higher adipocyte hypertrophy in both fat depots and increased fibrosis and expression of macrophage and hypoxia markers in SAT. Transcriptional data suggest increased fatty acid oxidation in SAT and impaired thermogenesis and extracellular matrix remodelling in VAT from MetS+ subjects. A sPLS-DA model, including SAT expression of PPARA and LEPR genes identified MetS with an AUC = 0.87. Despite equal age, BMI and body composition, MetS+ females display morphological and transcriptional differences in both WAT depots, especially in SAT. These factors may contribute to the transition to MetS.

Whole-body and adipose tissue metabolic phenotype in cancer patients.

BackgroundAltered adipose tissue (AT) metabolism in cancer‐associated weight loss via inflammation, lipolysis, and white adipose tissue (WAT) browning is primarily implicated from rodent models; their contribution to AT wasting in cancer patients is unclear.MethodsEnergy expenditure (EE), plasma, and abdominal subcutaneous WAT were obtained from men (aged 65 ± 8 years) with cancer, with (CWL, n = 27) or without (CWS, n = 47) weight loss, and weight‐stable non‐cancer patients (CON, n = 26). Clinical images were assessed for adipose and muscle area while plasma and WAT were assessed for inflammatory, lipolytic, and browning markers.ResultsCWL displayed smaller subcutaneous AT (SAT; P = 0.05) and visceral AT (VAT; P = 0.034) than CWS, and displayed higher circulating interleukin (IL)‐6 (P = 0.01) and WAT transcript levels of IL‐6 (P = 0.029), IL‐1β (P = 0.042), adipose triglyceride lipase (P = 0.026), and browning markers (Dio2, P = 0.03; PGC‐1a, P = 0.016) than CWS and CON. There was no difference across groups in absolute REE (P = 0.061), %predicted REE (P = 0.18), circulating free fatty acids (FFA, P = 0.13) or parathyroid hormone‐related peptide (PTHrP; P = 0.88), or WAT protein expression of inflammation (IL‐6, P = 0.51; IL‐1β, P = 0.29; monocyte chemoattractant protein‐1, P = 0.23) or WAT protein or gene expression of browning (uncoupling protein‐1, UCP‐1; P = 0.13, UCP‐1, P = 0.14). In patients with cancer, FFA was moderately correlated with WAT hormone‐sensitive lipase transcript (r = 0.38, P = 0.018, n = 39); circulating cytokines were not correlated with expression of WAT inflammatory markers and circulating PTHrP was not correlated with expression of WAT browning markers. In multivariate regression using cancer patients only, body mass index (BMI) directly predicted SAT (N = 25, R 2 = 0.72, P < 0.001), VAT (N = 28, R 2 = 0.64, P < 0.001), and absolute REE (N = 22, R 2 = 0.43, P = 0.001), while BMI and WAT UCP‐1 protein were indirectly associated with %predicted REE (N = 22, R 2 = 0.45, P = 0.02), and FFA was indirectly associated with RQ (N = 22, R 2 = 0.52, P < 0.001).ConclusionsCancer‐related weight loss was associated with elevated circulating IL‐6 and elevations in some WAT inflammatory, lipolytic and browning marker transcripts. BMI, not weight loss, was associated with increased energy expenditure. The contribution of inflammation and lipolysis, and lack thereof for WAT browning, will need to be clarified in other tumour types to increase generalizability. Future studies should consider variability in fat mass when exploring the relationship between cancer and adipose metabolism and should observe the trajectory of lipolysis and energy expenditure over time to establish the clinical significance of these associations and to inform more mechanistic interpretation of causation.

Long-term changes in adipose tissue gene expression following bariatric surgery.

Patients undergoing bariatric surgery present long-term metabolic improvements and reduced type 2 diabetes risk, despite long-term weight regain. We hypothesized that part of these protective effects could be linked to altered gene expression in white adipose tissue (WAT). Transcriptomic profiling by gene microarray was performed in abdominal subcutaneous WAT from women before (n=50) and two (n=49) and five (n=38) years after Roux-en-Y gastric bypass (RYGB) surgery as well as in 28 age-matched nonoperated women. In the obese women, the average body weight decrease was 38kg 2years postsurgery followed by an 8kg weight regain between 2 and 5years. Most of the long-term changes in WAT gene expression occurred during the first 2years. However, a subset of genes encoding proteins involved in inflammation displayed a continued decrease between baseline, 2 and 5years, respectively; that is an expression pattern independent of body weight regain. Expression of 71 of these genes correlated with measurements of adipocyte morphology or serum adipokine levels. The continuous improvement in WAT inflammatory gene expression, despite body weight relapse, may contribute to the sustained effects on adipose morphology after bariatric surgery.

Short-term High-fat Overfeeding Does Not Induce NF-κB Inflammatory Signaling in Subcutaneous White Adipose Tissue.

It is unclear how white adipose tissue (WAT) inflammatory signaling proteins respond during the early stages of overnutrition. To investigate the effect of short-term, high-fat overfeeding on fasting abdominal subcutaneous WAT total content and phosphorylation of proteins involved in nuclear factor-κB (NF-κB) inflammatory signaling, systemic metabolic and inflammatory biomarkers. Individuals consumed a high-fat (65% total energy from total fat), high-energy (50% above estimated energy requirements) diet for 7 days. Fifteen participants (aged 27 ± 1 years; body mass index 24.4 ± 0.6 kg/m2) completed the study. Body mass increased following high-fat overfeeding (+1.2 ± 0.2 kg; P < 0.0001). However, total content and phosphorylation of proteins involved in NF-κB inflammatory signaling were unchanged following the intervention. Fasting serum glucose (+0.2 ± 0.0 mmol/L), total cholesterol (+0.4 ± 0.1 mmol/L), low-density lipoprotein cholesterol (+0.3 ± 0.1 mmol/L), high-density lipoprotein cholesterol (+0.2 ± 0.0 mmol/L), and lipopolysaccharide-binding protein (LBP; +4.7 ± 2.1 µg/mL) increased, whereas triacylglycerol concentrations (-0.2 ± 0.1 mmol/L) decreased following overfeeding (all P < 0.05). Systemic biomarkers (insulin, soluble cluster of differentiation 14 [CD14], C-reactive protein, interleukin-6, tumor necrosis factor-α and monocyte chemoattractant protein-1) and the proportion and concentration of circulating CD14+ monocytes were unaffected by overfeeding. Acute lipid oversupply did not impact on total content or phosphorylation of proteins involved in WAT NF-κB inflammatory signaling, despite modest weight gain and metabolic alterations. Systemic LBP, which is implicated in the progression of low-grade inflammation during the development of obesity, increased in response to a 7-day high-fat overfeeding period.

Transplantation of adipose tissue lacking PAI-1 improves glucose tolerance and attenuates cardiac metabolic abnormalities in high-fat diet-induced obesity

ABSTRACT Adipose tissue is an important metabolic organ, and transplantation of white adipose tissue plays crucial roles in glucose homoeostasis and energy metabolism. However, how adipose tissue affects glucose utilization is poorly understood. PAI-1-knockout (PAI-1KO) mice were previously shown to be resistant to a high-fat diet and obesity. We used microPET/CT (positron emission tomography/computed tomography), gene microarray, and biochemical assays to measure changes in systemic and myocardial glucose metabolism in mice subjected to transplantation of adipose tissue from PAI-1KO and wild-type mice. Here, we show that transplanting subcutaneous white adipose tissue (scWAT) from PAI-1KO mice into high-fat diet (HFD)-fed mice reduced levels of serum total cholesterol and triglycerides, and improved glucose tolerance in the HFD-fed mice. microPET/CT imaging revealed that cardiac glucose uptake was increased in the heart but not in the liver, hindlimb muscles, or abdominal subcutaneous white adipose tissue in HFD-fed mice transplanted with PAI-1KO scWAT, suggesting that the transplanted PAI-1KO scWAT exerted endocrine effects in the heart. In addition, transplantation of scWAT from PAI-1KO mice upregulated mitochondrial gene expression in cardiac muscle, increased the expression of glucose transporters 1 and 4 in cardiac tissues and was associated with an increased NAD+/NADH ratio. Together, these findings suggest that modulating PAI-1 in scWAT may provide a promising approach for intervening in glucose metabolism.

Prospective analyses of white adipose tissue gene expression in relation to long-term body weight changes.

Transcriptome analysis of abdominal subcutaneous white adipose tissue (sWAT) has identified important obesity-associated disturbances. However, the relation between sWAT transcriptome and long-term future changes in body weight remains elusive. To investigate sWAT transcriptome signatures before and after long-term weight changes and assess their predictive value for body weight changes. A total of 56 women were followed longitudinally and subdivided into weight-stable (WS, n = 25), weight-gaining (WG, n = 14) and weight-losing (WL, n = 17) groups between baseline and follow-up (13 ± 1 years). The fasting sWAT transcriptome was analyzed by gene microarray at baseline and follow-up. Key genes associated with weight changes were validated using quantitative real-time PCR. In total 285 transcripts exhibited difference (FDR < 30%) in expression fold change over time between WL and WS women. WL women displayed decreased pro-inflammatory (NLRP3) but increased insulin-response gene (FASN and GLUT4) expression over time. In comparison, 461 transcripts displayed difference in expression fold change over time between WG and WS women (P < 0.05). Genes involved in autophagic processes (CDK5, SQSTM1 and FBXL2) were generally upregulated in WG women. At baseline, 307 and 302 transcripts were differentially expressed (FDR < 30%) in WL and WG women, respectively, when independently compared against WS women. Baseline expression of adipogenic and lipogenic genes (PPARG, IRS2 and HACD2) was lower, while pro-fibrotic (COL6A1) was higher, in WL than WS women; whereas protein processing genes were lower expressed in WG than in WS women. In adult women, long-term body weight change associates with altered sWAT transcriptome. Expression of genes associated with inflammation, insulin response, adipogenesis and lipogenesis are linked to weight loss. However, other pathways such as autophagy not only associate but also predict future weight gain suggesting that intrinsic factors in sWAT impact tissue expansion.

Photoactivation of Autologous Transplantation of Subcutaneous Adipose Tissue Improves Glucose Homeostasis

Photoactivation of autologous transplantation of subcutaneous adipose tissue improves glucose homeostasis Increasing evidences indicated that normal adipose tissue transplantation improves whole-body energy metabolism and glucose homeostasis in a high-fat diet (HFD)-induced obese mice model. Adipose tissue macrophage is associated with glucose homeostasis and insulin resistance in type 2 diabetes and obese humans, offering a potential target for therapeutics. However, whether transplantation of autologous AT that changed macrophage phenotype directly contribute to systemic glucose intolerance has not been determined. Here we specifically developed our device, with more specific wavelengths of light, to activate macrophage phenotype in isolated sWAT from HFD mice. We found that the macrophage polarization, M1 marker genes expression, such as CD11c, IL-6 and monocyte chemoattractant protein-1, but also the M1-to-M2 ratio were increased by an HFD and decreased by photoactivation treatment. Furthermore, autologous transplantation of photoactivated sWAT into a HFD mice reduced blood glucose level and caused significant improvement in glucose tolerance, which was not shown in a sham-operated or non-photoactivated sWAT HFD mice. Moreover, Positron emission/computed tomography scans indicated higher glucose uptake in heart, but not liver, hindlimb muscles, and abdominal subcutaneous white adipose tissue. These data suggested that the correlation with photoactivation to shift ATMs polarization of HFD mice caused significant improvement in glucose homeostasis, and that autologous transplantation might be a promising therapeutic option for the treatment of diabetes. Disclosure J. Wu: None.

Substantial Metabolic Activity of Human Brown Adipose Tissue during Warm Conditions and Cold-Induced Lipolysis of Local Triglycerides

SummaryCurrent understanding of in vivo human brown adipose tissue (BAT) physiology is limited by a reliance on positron emission tomography (PET)/computed tomography (CT) scanning, which has measured exogenous glucose and fatty acid uptake but not quantified endogenous substrate utilization by BAT. Six lean, healthy men underwent 18fluorodeoxyglucose-PET/CT scanning to localize BAT so microdialysis catheters could be inserted in supraclavicular BAT under CT guidance and in abdominal subcutaneous white adipose tissue (WAT). Arterial and dialysate samples were collected during warm (∼25°C) and cold exposure (∼17°C), and blood flow was measured by 133xenon washout. During warm conditions, there was increased glucose uptake and lactate release and decreased glycerol release by BAT compared with WAT. Cold exposure increased blood flow, glycerol release, and glucose and glutamate uptake only by BAT. This novel use of microdialysis reveals that human BAT is metabolically active during warm conditions. BAT activation substantially increases local lipolysis but also utilization of other substrates such as glutamate.

Global transcriptome profiling identifies KLF15 and SLC25A10 as modifiers of adipocytes insulin sensitivity in obese women.

Although the mechanisms linking obesity to insulin resistance (IR) and type 2 diabetes (T2D) are not entirely understood, it is likely that alterations of adipose tissue function are involved. The aim of this study was to identify new genes controlling insulin sensitivity in adipocytes from obese women with either insulin resistant (OIR) or sensitive (OIS) adipocytes. Insulin sensitivity was first determined by measuring lipogenesis in isolated adipocytes from abdominal subcutaneous white adipose tissue (WAT) in a large observational study. Lipogenesis was measured under conditions where glucose transport was the rate limiting step and reflects in vivo insulin sensitivity. We then performed microarray-based transcriptome profiling on subcutaneous WAT specimen from a subgroup of 9 lean, 21 OIS and 18 obese OIR women. We could identify 432 genes that were differentially expressed between the OIR and OIS group (FDR ≤5%). These genes are enriched in pathways related to glucose and amino acid metabolism, cellular respiration, and insulin signaling, and include genes such as SLC2A4, AKT2, as well as genes coding for enzymes in the mitochondria respiratory chain. Two IR-associated genes, KLF15 encoding a transcription factor and SLC25A10 encoding a dicarboxylate carrier, were selected for functional evaluation in adipocytes differentiated in vitro. Knockdown of KLF15 and SLC25A10 using siRNA inhibited insulin-stimulated lipogenesis in adipocytes. Transcriptome profiling of siRNA-treated cells suggested that KLF15 might control insulin sensitivity by influencing expression of PPARG, PXMP2, AQP7, LPL and genes in the mitochondrial respiratory chain. Knockdown of SLC25A10 had only modest impact on the transcriptome, suggesting that it might directly influence insulin sensitivity in adipocytes independently of transcription due to its important role in fatty acid synthesis. In summary, this study identifies novel genes associated with insulin sensitivity in adipocytes in women independently of obesity. KFL15 and SLC25A10 are inhibitors of insulin-stimulated lipogenesis under conditions when glucose transport is the rate limiting step.

CD146 (MCAM) in human cs-DLK1−/cs-CD34+ adipose stromal/progenitor cells

To precisely characterize CD146 in adipose stromal/progenitor cells (ASCs) we sorted the stromal vascular faction (SVF) of human abdominal subcutaneous white adipose tissue (sWAT) according to cell surface (cs) expression of CD146, DLK1 and CD34. This test identified three main SVF cell populations: ~50% cs-DLK1−/cs-CD34+/cs-CD146− ASCs, ~7.5% cs-DLK1+/cs-CD34dim/+/cs-CD146+ and ~7.5% cs-DLK1+/cs-CD34dim/+/cs-CD146− cells. All cells contained intracellular CD146. Whole mount fluorescent IHC staining of small vessels detected CD146+ endothelial cells (CD31+/CD34+/CD146+) and pericytes (CD31−/CD34−/CD146+ ASCs). The cells in the outer adventitial layer showed the typical ASC morphology, were strongly CD34+ and contained low amounts of intracellular CD146 protein (CD31−/CD34+/CD146+). Additionally, we detected wavy CD34−/CD146+ and CD34dim/CD146+ cells. CD34dim/CD146+ cells were slightly more bulky than CD34−/CD146+ cells. Both CD34−/CD146+ and CD34dim/CD146+ cells were detached from the inner pericyte layer and protruded into the outer adventitial layer. Cultured early passage ASCs contained low levels of CD146 mRNA, which was expressed in two different splicing variants, at a relatively high amount of the CD146-long form and at a relatively low amount of the CD146-short form. ASCs contained low levels of CD146 protein, which consisted predominantly long form and a small amount of short form. The CD146 protein was highly stable, and the majority of the protein was localized in the Golgi apparatus. In conclusion, the present study contributes to a better understanding of the spatial localization of CD34+/CD146+ and CD34−/CD146+ cells in the adipose niche of sWAT and identifies CD146 as intracellular protein in cs-DLK1−/cs-CD34+/cs-CD146− ASCs.

Effect of Mixed‐Carotenoid Supplementation and Physical Activity on Irisin and Adiponectin: A 6‐Month Double Blind Placebo‐Controlled Pilot Study in Children with Obesity

BodyShort term supplementation with mixed‐carotenoids (MCA) and physical activity reduces the accrual of abdominal subcutaneous white adipose tissue (scWAT) in children with obesity. Presumptive mechanisms may involve the induction of thermogenic beigeing and myo‐adipocytokines such as irisin, high‐molecular weight adiponectin (HMW‐ADI) and leptin.Method and DesignOf the 20 obese children recruited (Age = 126 ± 5 months), 17 completed a randomized double blind placebo controlled study involving one hour of physical activity for 10‐days of intense life‐style intervention followed by 6 months of usual lifestyle. Patients were randomized to MCA (Jarrow Formulas CaroteneAll®)5000 IU of beta‐carotene (BC) and alpha carotene; 20 mg of lutein; 4 mg of zeaxanthin, 20 mg of lycopene; 1000 mcg of astaxanthin; and 20 mg of gamma tocopherol vs. placebo at entry and were sampled at baseline, three weeks and 6 months. BC measured by HPLC, leptin measured by RIA and HMW‐adiponectin and irisin were measured by ELISA. The percent change in visceral (vWAT) and scWAT was determined by quantitative cross‐sectional multi‐slice MRI (1.5‐T; GE Medical Systems) at baseline and 6 months.ResultsBC was inversely related to BMI Z‐score, vWAT and scWAT (p&lt;0.05 for all). Supplementation resulted in 95 ± 66% increase in BC at 6 months as compared to 3 ± 19% decrease in the placebo group (p=0.001). Pair‐wise comparisons for treatment effects based on estimated marginal mean ± SEM showed there was a 4.1±1.7 ng/mL (p=0.033) increase in irisin at three weeks and a 4.8±1.8 ng/ml (p=0.018) increase in HMW‐adiponectin at six month between supplement and placebo groups after Bonferroni adjustments for age, gender and baseline BMI z‐score. There was a 4% decrease in mean scWAT by MRI in the supplement group (p=0.016) after six months.ConclusionMCA significantly increased irisin after 10 days of physical activity and HMW‐adiponectin after 6 months of supplementation as compared to placebo. These changes may contribute to the decrease in scWAT accrual at 6 months mediated by the induction of thermogenic beigeing signals. Further studies are warranted.Support or Funding InformationThe Players Center for Child Health at Wolfson Children's Hospital

A novel thermoregulatory role for PDE10A in mouse and human adipocytes.

Phosphodiesterase type 10A (PDE10A) is highly enriched in striatum and is under evaluation as a drug target for several psychiatric/neurodegenerative diseases. Preclinical studies implicate PDE10A in the regulation of energy homeostasis, but the mechanisms remain unclear. By utilizing small‐animal PET/MRI and the novel radioligand [18F]‐AQ28A, we found marked levels of PDE10A in interscapular brown adipose tissue (BAT) of mice. Pharmacological inactivation of PDE10A with the highly selective inhibitor MP‐10 recruited BAT and potentiated thermogenesis in vivo. In diet‐induced obese mice, chronic administration of MP‐10 caused weight loss associated with increased energy expenditure, browning of white adipose tissue, and improved insulin sensitivity. Analysis of human PET data further revealed marked levels of PDE10A in the supraclavicular region where brown/beige adipocytes are clustered in adults. Finally, the inhibition of PDE10A with MP‐10 stimulated thermogenic gene expression in human brown adipocytes and induced browning of human white adipocytes. Collectively, our findings highlight a novel thermoregulatory role for PDE10A in mouse and human adipocytes and promote PDE10A inhibitors as promising candidates for the treatment of obesity and diabetes.

Activating brown adipose tissue through exercise (ACTIBATE) in young adults: Rationale, design and methodology

AimsThe energy expenditure capacity of brown adipose tissue (BAT) makes it an attractive target as a therapy against obesity and type 2 diabetes. BAT activators namely catecholamines, natriuretic peptides and certain myokines, are secreted in response to exercise. ACTIBATE will determine the effect of exercise on BAT activity and mass measured by positron emission tomography/computed tomography (PET/CT, primary outcome) in young adults. ACTIBATE will also investigate the physiological consequences of activating BAT (secondary outcomes). MethodsACTIBATE will recruit 150 sedentary, healthy, young adults (50% women) aged 18–25years. Eligible participants will be randomly assigned to a non-exercise group (n≈50) or one of two exercise groups (n=50 each). Participants in the exercise groups will perform aerobic and strength training 3–4days/week at a heart rate equivalent to 60% of heart rate reserve (HRres), and at 50% of 1 repetition maximum (RM) for the moderate-intensity group, and at 80% of HRres and 70% RM for the vigorous-intensity group. Laboratory measures completed at baseline and 6months include BAT activity and mass, resting energy expenditure, meal and cold-induced thermogenesis, body temperature regulation and shivering threshold, body composition and cardiovascular disease risk factors. We will also obtain biopsies from abdominal subcutaneous white adipose tissue and skeletal muscle to analyse the expression of genes encoding proteins involved in the thermogenic machinery. DiscussionFindings from ACTIBATE will have significant implications for our understanding of exercise and its protective effects against the development of type 2 diabetes, obesity and related metabolic diseases.ClinicalTrials.gov ID: NCT02365129

Low early B-cell factor 1 (EBF1) activity in human subcutaneous adipose tissue is linked to a pernicious metabolic profile

AimRecently, in both human and murine white adipose tissue (WAT), transcription factor early B-cell factor 1 (EBF1) has been shown to regulate adipocyte differentiation, adipose morphology and triglyceride hydrolysis (lipolysis). This study investigated whether EBF1 expression and biological activity in WAT is related to different metabolic parameters. MethodsIn this cross-sectional study of abdominal subcutaneous WAT, EBF1 protein levels were examined in 18 non-obese subjects, while biological activity was determined in 56 obese and non-obese subjects. Results were assessed by anthropometric measures and blood pressure as well as by plasma lipid levels and insulin sensitivity. ResultsEBF1 protein levels were negatively associated with waist circumference (r=−0.56; P=0.015), but not with body mass index (BMI) or body fat (P=0.10–0.29). Biological activity of EBF1 correlated negatively with plasma triglycerides (r=−0.46; P=0.0005) and plasma insulin (r=−0.39; P=0.0027), but positively with plasma HDL cholesterol (r=0.48; P=0.0002) and insulin sensitivity, as assessed by intravenous insulin tolerance test (r=0.64; P<0.0001). These relationships, except for plasma insulin, remained statistically significant after adjusting for BMI and adipose morphology. EBF1 activity was not associated with age, systolic/diastolic blood pressure or total plasma cholesterol (P=0.17–0.48). In contrast to EBF1 activity, after adjusting for BMI, EBF1 mRNA levels displayed only an association with plasma triglycerides. ConclusionLow EBF1 protein expression and activity in abdominal subcutaneous WAT is a BMI-independent marker for several traits associated with the metabolic syndrome. However, whether EBF1 constitutes a novel treatment target remains to be demonstrated.

P0008 Validating the link between obesity and breast inflammation in women with breast cancer

Background In post-menopausal women, obesity is a risk factor for hormone sensitive breast cancer. We previously described crown-like structures (CLS), consisting of macrophages surrounding dead adipocytes, in the breast tissues of mice and humans. CLS were associated with increased levels of proinflammatory mediators known to be involved in carcinogenesis. We provided the first evidence of CLS in the human breast (CLS-B), which correlated with increased aromatase expression and activity. Here, we expanded our population to prospectively validate these preliminary findings. Methods White adipose tissue (WAT) was prospectively collected from women undergoing breast and reconstructive surgery. WAT was subjected to immunohistochemistry for CD68, a macrophage marker, to detect CLS-B by light microscopy. Adipocyte diameter was measured using the Canvas 11 Software. Endpoints were CLS-B presence/absence and CLS-B index (proportion of slides with CLS-B). Findings From April 2010 to February 2012, WAT (100 mastectomy and five abdominal reconstructions) was obtained from 101 American women; median age 49 years (range 26–80). CLS-B were found in 54 (53%) patients. CLS-B were seen in 9/37 (24%) normal weight patients (body mass index [BMI] μ m) compared with those without CLS-B (91.5 ± 16.1 μm; p p = 0.04). Among 25 patients with bilateral breast WAT and five patients with paired breast and abdominal WAT, concordant CLS-B findings (+/–) were seen in 80%. Interpretation Findings from this prospective study confirm that CLS-B are associated with BMI and adipocyte size. These results provide a plausible pathophysiological link between obesity and breast cancer. Abdominal WAT may be a surrogate for breast WAT inflammation; biopsies of abdominal subcutaneous WAT are more easily done, and could be performed in future clinical trials that aim to decrease breast WAT inflammation.

Abstract P1-06-03: Validating the link between obesity and breast inflammation in women with breast cancer (BC)

Abstract Background: In post-menopausal women, obesity is a risk factor for the development of BC that expresses the estrogen and progesterone receptors (ER/PR). In mouse models of obesity, we previously described crown-like structures (CLS), consisting of macrophages surrounding dead adipocytes in white adipose tissue (WAT) of the mammary gland, which were associated with increased levels of proinflammatory mediators known to be involved in carcinogenesis. We translated these findings to women (n = 30), and provided the first evidence of CLS in the human breast (CLS-B). The presence and severity of CLS-B (CLS-B index) correlated with elevated body mass index (BMI), increased adipocyte size, activation of NF-κB, and increased levels of proinflammatory mediators (TNF-α, IL-1β, COX-2 and PGE2) and aromatase. We expanded our population to prospectively validate these preliminary findings. Methods: We prospectively collected WAT from women undergoing breast and reconstructive surgery. WAT was subjected to immunohistochemistry for CD68, a macrophage marker, to detect CLS-B by light microscopy. Adipocyte diameter was measured on photomicrographs using the Canvas 11 Software. Endpoints were 1) CLS-B presence/absence and 2) CLS-B index (proportion of slides with CLS-B). Associations between CLS-B and clinicopathologic features were analyzed using logistic regression and Fisher's exact test. Results: From 04/2010-02/2012, WAT (100 mastectomy and 5 abdominal reconstructions) was obtained from 101 women; median age 49 (range 26-80). CLS-B were found in 54 (53%) patients (pts). CLS-B were seen in 9/37 (24%) normal weight pts (BMI &amp;lt;25), 23/39 (59%) overweight pts (BMI 25-29.9), and 22/25 (88%) obese pts (BMI ≥30). Pts with CLS-B had significantly larger average adipocyte diameter (106.5 +/- 11.5 microns) compared to those without CLS-B (91.5 +/- 16.1 microns; p&amp;lt;0.001). Consistently, CLS-B index correlated with BMI (p&amp;lt;0.001) and adipocyte size (p&amp;lt;0.001). Breast inflammation was seen in pts with all tumor phenotypes: CLS-B were seen in 24/41 (59%) pts with ER/PR+, HER2- tumors; 7/16 (44%) pts with HER2+ tumors; and 3/10 (30%) pts with ER/PR/HER2- tumors. A higher CLS-B index was seen in WAT from ER+ tumors, but this was not statistically significant (p = 0.08). Regular use of nonsteroidal antiinflammatory drugs was protective against CLS-B (p = 0.17 for association with CLS-B, and p = 0.04 for association with CLS-B index in multivariable analyses). Among 25 pts with bilateral breast WAT, concordant CLS-B findings (+/-) were found in 20 (80%) pts. Among pts with paired breast and abdominal WAT, concordant findings were seen in 4/5 (80%) pts. Conclusions: Findings from this prospective study, the largest reported to date, extend our previous observation that CLS-B are associated with BMI and adipocyte size. These results provide a plausible pathophysiological link between obesity and BC. Breast inflammation occurs in association with all BC phenotypes. Preliminary data suggest concordance between breasts and between abdominal and breast WAT. Hence, abdominal WAT may prove useful as a surrogate for breast WAT; biopsies of abdominal subcutaneous WAT are more easily done, which could prove useful in developing interventions to attenuate WAT inflammation. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-06-03.

HMGA2 expression in white adipose tissue linking cellular senescence with diabetes

There is a clear link between overweight, gain of white adipose tissue, and diabetes type 2 (T2D). The molecular mechanism of the gain of adipose tissue is linked with the expression of high mobility group protein AT-hook 2 (HMGA2), and recent studies revealed an association with a SNP near HMGA2. In this study, we investigated the gene expression of HMGA2, p14 (Arf) , CDKN1A, and BAX in human abdominal subcutaneous white adipose tissue from 157 patients. We found a significant higher HMGA2 expression in obese individuals than in non-obese patients. Furthermore, the HMGA2 expression in white adipose tissue in patient with type 2 diabetes was significantly higher than in nondiabetic patients. There is an association between the DNA-binding nonhistone protein HMGA2 and the risk of developing T2D that remains mechanistically unexplained so far. Likewise, p14(Arf), an inducer of cellular senescence, has been associated with the occurrence of T2D. The data of the present study provide evidence that both proteins act within the same network to drive proliferation of adipose tissue stem and precursor cells, senescence, and increased risk of T2D, respectively.