Subcutaneous Adipose Tissue Gene Research Articles

Markers of Adipogenesis, but Not Inflammation, in Adipose Tissue Are Independently Related to Insulin Sensitivity.

In obesity, adipose tissue (AT) undergoes dynamic remodeling, including an alternation in adipogenesis, AT-resident cell content, angiogenesis, and turnover of extracellular matrix (ECM) components. Studies of AT in humans have been carried out mostly in people with severe metabolic abnormalities, like type 2 diabetes or morbid obesity. The purpose of this study was to investigate subcutaneous AT gene expression of markers of adipogenesis, ECM remodeling, and inflammation in young, healthy, overweight or obese subjects. The study group comprised 83 normal-weight, 48 overweight, and 19 obese subjects. Euglycemic hyperinsulinemic clamp, biopsy of subcutaneous AT, and isolation of peripheral blood mononuclear cells (PBMCs) were performed. Gene expression was measured with real-time polymerase chain reaction. Overweight/obese subjects had lower AT expression of markers of adipogenesis, insulin signaling, and angiogenesis; higher expression of markers of ECM remodeling; altered expression of genes of the nuclear factor-κ-B (NFκB), but not c-Jun NH2-terminal kinase, pathway; and higher expression of macrophage markers but not markers of other immune cells. In multiple regression analysis, the expression of CEBPA, ADIPOQ, IRS1, IRS2, SLC2A4, and MMP9 was associated with insulin sensitivity independently of body mass index. No differences were found in inflammatory-gene PBMC expression. Overweight/obesity is associated with altered expression of genes of adipogenesis, insulin signaling, ECM remodeling, and inflammation. NFκB seems to be the earliest inflammatory pathway altered at the transcriptional level in AT. Macrophages seem to be the first immune cells to infiltrate AT. Adipogenesis and ECM remodeling are the initial processes in AT that are independently associated with insulin sensitivity.

Copy Number Variants Are Enriched in Individuals With Early-Onset Obesity and Highlight Novel Pathogenic Pathways.

Only a few genetic causes for childhood obesity have been identified to date. Copy number variants (CNVs) are known to contribute to obesity, both syndromic (15q11.2 deletions, Prader-Willi syndrome) and nonsyndromic (16p11.2 deletions) obesity. To study the contribution of CNVs to early-onset obesity and evaluate the expression of candidate genes in subcutaneous adipose tissue. A case-control study in a tertiary academic center. CNV analysis was performed on 90 subjects with early-onset obesity and 67 normal-weight controls. Subcutaneous adipose tissue from body mass index-discordant siblings was used for the gene expression analyses. We used custom high-density array comparative genomic hybridization with exon resolution in 1989 genes, including all known obesity loci. The expression of candidate genes was assessed using microarray analysis of messenger RNA from subcutaneous adipose tissue. We identified rare CNVs in 17 subjects (19%) with obesity and 2 controls (3%). In three cases (3%), the identified variant involved a known syndromic lesion (22q11.21 duplication, 1q21.1 deletion, and 16p11.2 deletion, respectively), although the others were not known. Seven CNVs in 10 families were inherited and segregated with obesity. Expression analysis of 37 candidate genes showed discordant expression for 10 genes (PCM1, EFEMP1, MAMLD1, ACP6, BAZ2B, SORBS1, KLF15, MACROD2, ATR, and MBD5). Rare CNVs contribute possibly pathogenic alleles to a substantial fraction of children with early-onset obesity. The involved genes might provide insights into pathogenic mechanisms and involved cellular pathways. These findings highlight the importance of CNV screening in children with early-onset obesity.

Upregulation of Early and Downregulation of Terminal Pathway Complement Genes in Subcutaneous Adipose Tissue and Adipocytes in Acquired Obesity.

Inflammation is an important mediator of obesity-related complications such as the metabolic syndrome but its causes and mechanisms are unknown. As the complement system is a key mediator of inflammation, we studied whether it is activated in acquired obesity in subcutaneous adipose tissue (AT) and isolated adipocytes. We used a special study design of genetically matched controls of lean and heavy groups, rare monozygotic twin pairs discordant for body mass index (BMI) [n = 26, within-pair difference (Δ) in body mass index, BMI >3 kg/m2] with as much as 18 kg mean Δweight. Additionally, 14 BMI-concordant (BMI <3 kg/m2) served as a reference group. The detailed measurements included body composition (DEXA), fat distribution (MRI), glucose, insulin, adipokines, C3a and SC5b-9 levels, and the expression of complement and insulin signaling pathway-related genes in AT and adipocytes. In both AT and isolated adipocytes, the classical and alternative pathway genes were upregulated, and the terminal pathway genes downregulated in the heavier co-twins of the BMI-discordant pairs. The upregulated genes included C1q, C1s, C2, ficolin-1, factor H, receptors for C3a and C5a (C5aR1), and the iC3b receptor (CR3). While the terminal pathway components C5 and C6 were downregulated, its inhibitor clusterin was upregulated. Complement gene upregulation in AT and adipocytes correlated positively with adiposity and hyperinsulinemia and negatively with the expression of insulin signaling-related genes. Plasma C3a, but not SC5b-9, levels were elevated in the heavier co-twins. There were no differences between the co-twins in BMI-concordant pairs. Obesity is associated with increased expression of the early, but not late, complement pathway components and of key receptors. The twins with acquired obesity have therefore an inflated inflammatory activity in the AT. The results suggest that complement is likely involved in orchestrating clearance of apoptotic debris and inflammation in the AT.

Differential adipokine DNA methylation and gene expression in subcutaneous adipose tissue from adult offspring of women with diabetes in pregnancy

BackgroundOffspring of women with diabetes in pregnancy are at increased risk of type 2 diabetes mellitus (T2DM), potentially mediated by epigenetic mechanisms. The adipokines leptin, adiponectin, and resistin (genes: LEP, ADIPOQ, RETN) play key roles in the pathophysiology of T2DM. We hypothesized that offspring exposed to maternal diabetes exhibit alterations in epigenetic regulation of subcutaneous adipose tissue (SAT) adipokine transcription.We studied adipokine plasma levels, SAT gene expression, and DNA methylation of LEP, ADIPOQ, and RETN in adult offspring of women with gestational diabetes (O-GDM, N = 82) or type 1 diabetes (O-T1DM, N = 67) in pregnancy, compared to offspring of women from the background population (O-BP, N = 57).ResultsCompared to O-BP, we found elevated plasma leptin and resistin levels in O-T1DM, decreased gene expression of all adipokines in O-GDM, decreased RETN expression in O-T1DM, and increased LEP and ADIPOQ methylation in O-GDM. In multivariate regression analysis, O-GDM remained associated with increased ADIPOQ methylation and decreased ADIPOQ and RETN gene expression and O-T1DM remained associated with decreased RETN expression after adjustment for potential confounders and mediators.ConclusionsIn conclusion, offspring of women with diabetes in pregnancy exhibit increased ADIPOQ DNA methylation and decreased ADIPOQ and RETN gene expression in SAT. However, altered methylation and expression levels were not reflected in plasma protein levels, and the functional implications of these findings remain uncertain.

The role of dietary fatty acid intake in inflammatory gene expression: a critical review.

Diet is an important modifiable factor involved in obesity-induced inflammation. We reviewed clinical trials that assessed the effect of consumption of different fatty acids on the expression of inflammation-related genes, such as cytokines, adipokines, chemokines and transcription factors. Narrative review study conducted at a research center. This was a review on the effect of fat intake on inflammatory gene expression in humans. Consumption of saturated fatty acids (SFAs) was related to postprandial upregulation of genes associated with pro-inflammatory pathways in peripheral blood mononuclear cells (PBMCs), in comparison with monounsaturated fatty acid (MUFA) or polyunsaturated fatty acid (PUFA) intake. In addition, acute intake of a high-SFA meal also induced a postprandial pro-inflammatory response for several inflammatory genes in subcutaneous adipose tissue. Both high-MUFA and high-PUFA diets showed anti-inflammatory profiles, or at least a less pronounced pro-inflammatory response than did SFA consumption. However, the results concerning the best substitute for SFAs were divergent because of the large variability in doses of MUFA (20% to 72% of energy intake) and n3 PUFA (0.4 g to 23.7% of energy intake) used in interventions. The lipid profile of the diet can modulate the genes relating to postprandial and long-term inflammation in PBMCs and adipose tissue. Identifying the optimal fat profile for inflammatory control may be a promising approach for treating chronic diseases such as obesity.

Plasticity of adipose tissue in response to fasting and refeeding in male mice

BackgroundFasting is the most widely prescribed and self-imposed strategy for treating excessive weight gain and obesity, and has been shown to exert a number of beneficial effects. The aim of the present study was to determine the exact role of fasting and subsequent refeeding on fat distribution in mice.MethodsC57/BL6 mice fasted for 24 to 72 h and were then subjected to refeeding for 72 h. At 24, 48 and 72 h of fasting, and 12, 24, 48 and 72 h of refeeding, the mice were sacrificed, and serum and various adipose tissues were collected. Serum biochemical parameters, adipose tissue masses and histomorphological analysis of different depots were detected. MRNA was isolated from various adipose tissues, and the expressions of thermogenesis, visceral signature and lipid metabolism-related genes were examined. The phenotypes of adipose tissues between juvenile and adult mice subjected to fasting and refeeding were also compared.ResultsFasting preferentially consumed mesenteric fat mass and decreased the cell size of mesenteric depots; however, refeeding recovered the mass and morphology of inguinal adipose tissues preferentially compared with visceral depots. Thermogenesis-related gene expression in the inguinal WAT and interscapular BAT were suppressed. Mitochondrial biogenesis was affected by fasting in a depot-specific manner. Furthermore, a short period of fasting led to an increase in visceral signature genes (Wt1, Tcf21) in subcutaneous adipose tissue, while the expression of these genes decreased sharply as the fasting time increased. Additionally, lipogenesis-related markers were enhanced to a greater extent greater in subcutaneous depots compared with those in visceral adipose tissues by refeeding. Although similar phenotypic changes in adipose tissue were observed between juvenile mice and adult mice subjected to fasting and refeeding, the alterations appeared earlier and more sensitively in juvenile mice.ConclusionsFasting preferentially consumes lipids in visceral adipose tissues, whereas refeeding recovers lipids predominantly in subcutaneous adipose tissues, which indicated the significance of plasticity of adipose organs for fat distribution when subject to food deprivation or refeeding.

Adipose type I interferon signalling protects against metabolic dysfunction

ObjectiveLow-grade chronic inflammation emerges as a potent driver of insulin resistance and glucose dysregulation in obesity and associated non-alcoholic fatty liver disease (NAFLD). The liver, subcutaneous fat and the immune...

Upregulated TNF Expression 1\xa0Year After Bariatric Surgery Reflects a Cachexia-Like State in Subcutaneous Adipose Tissue

BackgroundAdipose tissue dysfunction contributes to obesity-associated chronic diseases. In the first year after bariatric surgery, obese patients significantly improve their metabolic status upon losing weight. We aimed to investigate whether changes in subcutaneous adipose tissue gene expression reflect a restoration of a healthy lean phenotype after bariatric surgery.MethodsThirty-one severely obese patients (BMI ≥ 40 kg/m2) were examined before and after surgery. subcutaneous adipose tissue (SAT) was collected during and 1 year after bariatric surgery. SAT from 20 matched lean and overweight patients (BMI < 30 kg/m2) was collected during elective abdominal surgery. Baseline characteristics and SAT gene expression relevant to glucose and lipid metabolism, inflammation, and apoptosis were analyzed.ResultsAfter surgery, mean BMI decreased from 46.1 ± 6.3 to 31.1 ± 5.7 kg/m2 and homeostasis model assessment of insulin resistance from 5.4 ± 5.3 to 0.8 ± 0.8. SAT expression of most analyzed inflammatory cytokines, growth factors, and metabolic and cell surface markers was greatly downregulated even compared to the lean cohort. In contrast, gene expression of TNF and CASP3 was significantly upregulated. Elastic net regression analysis showed that fasting glucose levels and CASP3 predicted increased TNF expression in the post-obese group.ConclusionsGene expression patterns in SAT 1 year after bariatric surgery point to a reduced inflammation. The unexpected high TNF expression in SAT of post-obese subjects is most likely not an indicator for inflammation, but rather an indicator for increased lipolysis and adipose tissue catabolism. Notably, after bariatric surgery SAT gene expression reflects a cachexia-like phenotype and differs from the lean state.

Gender-Specific Mechanisms Underlying the Amelioration of High-Fat Diet-Induced Glucose Intolerance in B-Cell-Activating Factor Deficient Mice.

It has recently been found that B cell activating factor (BAFF) plays an important role in the regulation of energy homeostasis. We also have previously reported that BAFF deficiency reverses high-fat (HF) diet-induced glucose intolerance by potentiating adipose tissue function. In the present study, we found that BAFF deficient (BAFF-/-) mice exhibit gender-specific differences in protection against diet-induced glucose intolerance, and aimed to characterize the gender-dependent molecular alterations in energy metabolism. Under HF feeding conditions, serum BAFF level of female wild-type (WT) mice was considerably higher than that of male mice. Despite increased body weight gain, both male and female BAFF-/- mice showed significantly improved glucose tolerance compared to their WT counterparts. Expressions of genes involved in glucose transport, thermogenesis and lipid oxidation were up-regulated in brown adipose tissues of both male and female BAFF-/- mice. Interestingly, the expression of thermogenic genes in subcutaneous adipose tissue was significantly enhanced in female BAFF-/- compared to WT mice, but the difference was not observed between male BAFF-/- and WT mice. The enhanced thermogenic program was confirmed by higher protein levels of UCP1 and irisin in female BAFF-/- than in WT mice. Additionally, adiponectin production in white adipose tissues and AMPK phosphorylation in subcutaneous adipose tissue were also significantly elevated in female BAFF-/- compared to WT mice, but not in male BAFF-/- mice. Our findings define a comprehensive scenario for the enhancing effect of BAFF depletion on glucose tolerance wherein the underlying mechanism is, at least in part, gender-specific, and suggest that gender difference should be considered as an important factor in the use of BAFF blockade as a therapeutic approach for the prevention and treatment of type 2 diabetes.

Adipose tissue transcriptomics and epigenomics in low birthweight men and controls: role of high-fat overfeeding

Individuals who had a low birthweight (LBW) are at an increased risk of insulin resistance and type 2 diabetes when exposed to high-fat overfeeding (HFO). We studied genome-wide mRNA expression and DNA methylation in subcutaneous adipose tissue (SAT) after 5 days of HFO and after a control diet in 40 young men, of whom 16 had LBW. mRNA expression was analysed using Affymetrix Human Gene 1.0 ST arrays and DNA methylation using Illumina 450K BeadChip arrays. We found differential DNA methylation at 53 sites in SAT from LBW vs normal birthweight (NBW) men (false discovery rate <5%), including sites in the FADS2 and CPLX1 genes previously associated with type 2 diabetes. When we used reference-free cell mixture adjustments to potentially adjust for cell composition, 4,323 sites had differential methylation in LBW vs NBW men. However, no differences in SAT gene expression levels were identified between LBW and NBW men. In the combined group of all 40 participants, 3,276 genes (16.5%) were differentially expressed in SAT after HFO (false discovery rate <5%) and there was no difference between LBW men and controls. The most strongly upregulated genes were ELOVL6, FADS2 and NNAT; in contrast, INSR, IRS2 and the SLC27A2 fatty acid transporter showed decreased expression after HFO. Interestingly, SLC27A2 expression correlated negatively with diabetes- and obesity-related traits in a replication cohort of 142 individuals. DNA methylation at 652 CpG sites (including in CDK5, IGFBP5 and SLC2A4) was altered in SAT after overfeeding in this and in another cohort. Young men who had a LBW exhibit epigenetic alterations in their adipose tissue that potentially influence insulin resistance and risk of type 2 diabetes. Short-term overfeeding influences gene transcription and, to some extent, DNA methylation in adipose tissue; there was no major difference in this response between LBW and control participants.

Effect of Roux-en-Y gastric bypass-induced weight loss on the transcriptomic profiling of subcutaneous adipose tissue

BackgroundThe changes in the transcriptomic profiling of subcutaneous adipose tissue (SAT) when weight loss stabilizes after a Roux-en-Y gastric bypass (RYGB) are still largely unknown. ObjectivesTo investigate the changes produced in SAT gene expression of morbidly obese women when their weight loss stabilizes 2 years after RYGB. SettingUniversity hospital. MethodsSAT biopsies of the periumbilical area were taken before and 2 years after RYGB. Gene expression levels were assessed by microarray analysis and significant differences in gene expression were validated by real-time quantitative polymerase chain reaction. The findings were also confirmed in an independent population of morbidly obese women. ResultsMicroarray analysis revealed that the overexpressed differentially expressed genes have a prominent role in the pathways involved in biosynthetic processes, especially lipid or carboxylic ones (stearoyl-Coenzyme A desaturase-1, fatty acid desaturase-1, fatty acid elongase-6, ATP citrate lyase, fatty acid synthase, lipin-1, monoacylglycerol O-acyltransferase, patatin-like phospholipase domain containing-3, phosphate cytidylyltransferase-2, cholesteryl ester transfer protein, transmembrane 7 superfamily member 2, pyruvate carboxylase, and glycogen synthase 2). Most of the underexpressed differentially expressed genes are related with immune system and inflammation processes (immune responses, response to stress, cell death, regulation of biological quality, immune effector process, the response to endogenous stimulus, and the response to other types of stimulus). ConclusionAn improvement of the SAT inflammatory and immune profile and an induction of genes involved in the regulation of lipid metabolism are shown when weight loss stabilizes 2 years after RYGB. Most of the genes shown are clearly linked to obesity and other metabolic disorders.

Regional distribution of body fat in relation to DNA methylation within the LPL, ADIPOQ and PPARγ promoters in subcutaneous adipose tissue.

Obesity may be related to differential DNA methylation and thus to differential expression of key genes in adipose tissue metabolism, such as LPL, ADIPOQ and PPARγ. Using subcutaneous adipose tissue (SAT) from 59 individuals of the European Prospective Investigation into Cancer and Nutrition–Potsdam study, we performed quantitative DNA methylation analysis within the promoters of LPL (LPL-CG1 and -CG2), ADIPOQ (ADIPOQ-CG1 and-CG2) and PPARγ (PPARγ-CG1). We then studied DNA methylation in relation to SAT gene expression, body composition measured using whole-body magnetic resonance imaging, body mass index (BMI), waist circumference (WC) and long-term changes in BMI and WC. For LPL-CG1 and LPL-CG2, higher methylation levels were associated with lower LPL expression, but with higher past WC gain. LPL-CG1 was also positively associated with BMI, WC, and visceral and subcutaneous fat mass. ADIPOQ-CG1 or -CG2 methylation exhibited no association with ADIPOQ expression or with anthropometric parameters. PPARγ-CG1 methylation was significantly higher in individuals with higher visceral fat mass. Among the investigated sites, LPL-CG1 methylation showed the strongest association with gene expression and regional body fat distribution, thereby possibly linking the degree of obesity with major metabolic processes in SAT.

Association of Adipose Tissue Inflammation With Histologic Severity of Nonalcoholic Fatty Liver Disease

The prevalence of nonalcoholic fatty liver disease (NAFLD) has increased with the obesity pandemic. We analyzed the transcriptional profiles of subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT), and phenotypes and functional characteristics of adipocyte tissue macrophages (ATMs), in obese patients undergoing bariatric surgery. We collected anthropometric data; plasma samples; and SAT, VAT, and liver tissues from 113 obese patients undergoing bariatric surgery at academic hospitals in Europe (Antwerp and Leuven) and South Africa. Based on clinical and histologic features, patients were assigned to the following groups: obese, NAFLD, nonalcoholic steatohepatitis (NASH), or NASH with fibrosis. Microarray analyses were performed to identify genes expressed differentially among groups. We measured levels of cytokines and chemokines in plasma samples and levels of RNAs in adipose tissues by quantitative reverse-transcription polymerase chain reaction. ATMs were isolated from patients and 13 lean individuals undergoing cholecystectomy (controls), analyzed by flow cytometry, and cultured; immunophenotypes and levels of cytokines and chemokines in supernatants were determined. We observed increased expression of genes that regulate inflammation in adipose tissues from patients with NAFLD and NASH; expression of these genes increased as disease progressed from NAFLD to NASH. We found 111 genes associated with inflammation that were expressed differentially between VAT and SAT. Serum levels of interleukin 8, chemokine (C-C motif) ligand 3, and tumor necrosis factor-α correlated with liver inflammation and NAFLD activity score. We developed 2 models that could be used to determine patients' liver histology based on gene expression in VAT and SAT. Flow cytometry showed increased proportions of CD11c+CD206+ and CCR2+ macrophages in VAT from patients with NASH, and supernatants of cultured macrophages had increased levels of cytokines and chemokines compared with controls. VAT and SAT from patients with NAFLD and NASH have an increased expression of genes that regulate inflammation, and ATM produce increased levels of inflammatory cytokines, compared with adipose tissues from controls. We identified an expression profile of 5 genes in SAT that accurately predict liver histology in these patients. Transcript profiling: accession numbers: GSE58979 and GSE59045.

Effects of DSP-8658, a novel selective peroxisome proliferator-activated receptors a/γ modulator, on adipogenesis and glucose metabolism in diabetic obese mice.

Peroxisome proliferator-activated receptors (PPARs) play a key regulating role in homeostasis. In this study, we investigated the effects of DSP-8658, a novel selective PPARa/γ modulator, on adipogenesis and glucose metabolism in diabetic obese mice and compared these effects to those of pioglitazone, a PPARγ full agonist. DSP-8658 functional activity was assessed by PPARγ-target genes expression in adipose 3T3-L1 cells and its anti-diabetic efficacy evaluated in db/db mice. The effects of DSP-8658 on adipogenesis were investigated diet induced obese (DIO) KK-A(y) mice. DSP-8658 reduced the expression of PPARγ-target gene 11 beta hydroxysteroid dehydrogenase type 1 with an EC50 value 2.1-fold that of pioglitazone and 28.4-fold that of rosiglitazone. On the other hand, DSP-8658 increased the expression of fatty acid binding protein 4 and glycerol kinase genes with EC50 values 33-fold and >15-fold those of pioglitazone and 163-fold and >38-fold those of rosiglitazone, respectively. In db/db mice, DSP-8658, like pioglitazone, decreased blood glucose, HbA1c, and plasma triglyceride levels and increased plasma insulin concentration and pancreatic insulin contents. In DIO KK-A(y) mice, DSP-8658, unlike pioglitazone, decreased subcutaneous adipose tissue weight and mean adipocyte size. However, both DSP-8658 and pioglitazone improved blood glucose and HbA1c levels with similar efficacy. Although DSP-8658 did not change the expression levels of fatty acid transport protein 1 and glycerol kinase genes in subcutaneous adipose tissue of KK-A(y) mice, pioglitazone increased these gene expression levels. Unlike PPARγ full agonists, DSP-8658 ameliorates blood glucose without increasing adipogenesis in diabetic obesity mice.

Roux-en-Y Gastric Bypass Acutely Decreases Protein Carbonylation and Increases Expression of Mitochondrial Biogenesis Genes in Subcutaneous Adipose Tissue.

Mitochondrial dysfunction in adipose tissue has been implicated as a pathogenic step in the development of type 2 diabetes mellitus (T2DM). In adipose tissue, chronic nutrient overload results in mitochondria driven increased reactive oxygen species (ROS) leading to carbonylation of proteins that impair mitochondrial function and downregulation of key genes linked to mitochondrial biogenesis. In patients with T2DM, Roux-en-Y gastric bypass (RYGB) surgery leads to improvements in glycemic profile prior to significant weight loss. Consequently, we hypothesized that improved glycemia early after RYGB would be paralleled by decreased protein carbonylation and increased expression of genes related to mitochondrial biogenesis in adipose tissue. To evaluate this hypothesis, 16 obese individuals were studied before and 7-8 days following RYGB and adjustable gastric banding (AGB). Subcutaneous adipose tissue was obtained pre- and post-bariatric surgery as well as from eight healthy, non-obese individual controls. Prior to surgery, adipose tissue expression of PGC1α, NRF1, Cyt C, and eNOS (but not Tfam) showed significantly lower expression in the obese bariatric surgery group when compared to lean controls (p < 0.05). Following RYGB, but not after AGB, patients showed significant decrease in HOMA-IR, reduction in adipose protein carbonylation, and increased expression of genes linked to mitochondrial biogenesis. These results suggest that rapid reduction in protein carbonylation and increased mitochondrial biogenesis may explain postoperative metabolic improvements following RYGB.

Relationships among Body Condition, Insulin Resistance and Subcutaneous Adipose Tissue Gene Expression during the Grazing Season in Mares

Obesity and insulin resistance have been shown to be risk factors for laminitis in horses. The objective of the study was to determine the effect of changes in body condition during the grazing season on insulin resistance and the expression of genes associated with obesity and insulin resistance in subcutaneous adipose tissue (SAT). Sixteen Finnhorse mares were grazing either on cultivated high-yielding pasture (CG) or semi-natural grassland (NG) from the end of May to the beginning of September. Body measurements, intravenous glucose tolerance test (IVGTT), and neck and tailhead SAT gene expressions were measured in May and September. At the end of grazing, CG had higher median body condition score (7 vs. 5.4, interquartile range 0.25 vs. 0.43; P=0.05) and body weight (618 kg vs. 572 kg ± 10.21 (mean ± SEM); P=0.02), and larger waist circumference (P=0.03) than NG. Neck fat thickness was not different between treatments. However, tailhead fat thickness was smaller in CG compared to NG in May (P=0.04), but this difference disappeared in September. Greater basal and peak insulin concentrations, and faster glucose clearance rate (P=0.03) during IVGTT were observed in CG compared to NG in September. A greater decrease in plasma non-esterified fatty acids during IVGTT (P<0.05) was noticed in CG compared to NG after grazing. There was down-regulation of insulin receptor, retinol binding protein 4, leptin, and monocyte chemoattractant protein-1, and up-regulation of adiponectin (ADIPOQ), adiponectin receptor 1 and stearoyl-CoA desaturase (SCD) gene expressions in SAT of both groups during the grazing season (P<0.05). Positive correlations were observed between ADIPOQ and its receptors and between SCD and ADIPOQ in SAT (P<0.01). In conclusion, grazing on CG had a moderate effect on responses during IVGTT, but did not trigger insulin resistance. Significant temporal differences in gene expression profiles were observed during the grazing season.

Expression of circadian genes in subcutaneous adipose tissue of obese men with glucose intolerance and type 2 diabetes

Objective: Accumulating evidence raises the hypothesis that dysregulation of intrinsic clock mechanisms which control the main metabolic processes are involved in the development of the most profound public health problems: obesity, metabolic syndrome and type 2 diabetes. We sought therefore to identify the dysregulation of molecular components of circadian clock in subcutaneous adipose tissue of obese men with impaired glucose tolerance and type 2 diabetes. Methods: We investigated the expression of key circadian genes by quantitative polymerase chain reaction (qPCR) in subcutaneous adipose tissue from 24 adult males divided into four equal groups: lean controls and obese men with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and type 2 diabetes. Results: The expression levels of circadian genes PER2, CLOCK, ARNTL/BMAL1 and CRY1 were decreased in subcutaneous adipose tissue of NGT obese men versus lean controls and these changes were negatively correlated with increased body mass index (BMI). At the same time, no significant changes were observed in PER1 gene expression in adipose tissue of this group of patients. In subcutaneous adipose tissue of IGT obese cases we found decreased levels of PER1, CLOCK and ARNTL/BMAL1 gene expressions compared to NGT obese individuals. Moreover, the expression levels of CLOCK, PER2 and CRY1 genes were down-regulated in subcutaneous adipose tissue of obese men with type 2 diabetes versus IGT obese patients; however, ARNTL/BMAL1 gene expression was up-regulated. Conclusions: Our data demonstrate that suppression of most circadian gene expressions in subcutaneous adipose tissue of obese men with NGT is negatively correlated with increased BMI and can contribute to the development of obesity. The decreased expression of PER1 gene as well as an additional suppression of ARNTL/BMAL1 and CLOCK gene expressions in subcutaneous adipose tissue of obese men with glucose intolerance is associated with insulin resistance and IGT. At the same time, development of type 2 diabetes in obese men correlates with suppression of CLOCK, PER2, and CRY1 gene expressions. These results demonstrate that obesity and its complications differentially suppress clock gene expressions in subcutaneous adipose tissue, rendering this pathway as a potential therapeutic target.

Higher circulating leukocytes in women with PCOS is reversed by aerobic exercise

Polycystic ovary syndrome (PCOS) is characterized by insulin resistance, elevated circulating leukocytes, and hypothesized to have higher adipose tissue inflammation. Aerobic exercise reduces circulating leukocytes and improves insulin sensitivity in obese individuals, but the effect of exercise on inflammation in PCOS is not known. We investigated circulating leukocytes, insulin sensitivity by euglycemic-hyperinsulinemic clamp, serum pro- and anti-inflammatory markers (hsCRP, TNF-α, total and high molecular weight adiponectin), and abdominal subcutaneous adipose tissue (SAT) gene expression of proinflammatory markers in 8 PCOS women and 8 obese control females matched for BMI. Additionally, in a prospective study, the 8 women with PCOS underwent a 16-week aerobic exercise regimen with the same measures performed post-intervention. Compared to controls, white blood cell counts (WBC) were 30% higher (p=0.04) and circulating total adiponectin levels were 150% lower (p=0.03) in women with PCOS at baseline/pre-exercise conditions. SAT gene expression of macrophage migration inhibitory factor (MIF, p<0.01) and interleukin-6 (IL-6, p<0.05) were also lower in women with PCOS. In response to 16 weeks of aerobic exercise, insulin sensitivity improved (p<0.01) and WBC counts decreased (p=0.02). The exercise-induced change in WBC and circulating neutrophils correlated inversely with changes in glucose disposal rate (r=-0.73, p=0.03; and r=-0.82, p=0.01, respectively). Aerobic exercise reduced serum leptin (p<0.05) after 4 weeks, trended to reduce the ratio of leptin-to-high molecular weight adiponectin (p<0.1) by the 8th week, and significantly increased serum dehydroepiandrosterone sulfate (DHEA-S, p<0.001) after 16 weeks. In conclusion, women with PCOS have higher circulating leukocytes compared to controls, which can be reversed by aerobic exercise and is associated with improvements in insulin sensitivity.

Expression of lipid metabolism related genes in subcutaneous adipose tissue from Chilota lambs grazing on two different pasture types

The focus of the present study was to investigate how the different chemical and botanical composition of two different pasture types, Calafatal pasture (CP) and naturalized pasture (NP), affect gene/protein expression levels of lipogenic enzymes and transcription factors (ACC, FAS, SCD1, and SREBP‐1c) as well as the concentrations of their fatty acid products in subcutaneous adipose tissue of Chilota lambs. Sixteen male Chilota lambs kept under different grazing conditions, CP versus NP, in Chiloé Archipelago (Chile) were included in the experiment. QRT‐PCR, western blot and fatty acid analysis were performed of subcutaneous adipose tissue samples. Compared to NP, CP diet induced a 1.51‐fold increase of ACACA expression, a 1.60‐fold rise of FASN expression and a 1.56‐fold elevation of SREBF1 expression. SCD gene expression did not significantly differ between both feeding groups. Different pasture types did not affect protein expression levels of lipogenic enzymes (ACC, FAS, and SCD1) and transcription factor pSREBP‐1c (precursor form) and mSREBP‐1c (mature form) in subcutaneous fat of lambs. Amounts of single and the sum of saturated fatty acids were significantly higher in subcutaneous fat samples of lambs fed NP than of lambs fed CP. Concentrations of single PUFA and the sum n‐3 and n‐6 PUFA and the n‐6/n‐3 PUFA ratio were not affected by different pasture types. The inclusion of different adipose tissue depots and more sampling “endpoints” during animal growth may be beneficial to comprehensively elucidate the mechanisms by which dietary PUFA intervention affects the lipid metabolism of adipose tissues in lambs.Practical applications: Increasing public awareness of the health benefits attributable to PUFA (n‐3 PUFA) has stimulated interest in sources of these fatty acids for human consumption. In relation to lamb adipose and muscle tissue, it is considered a good source of nutrients such as PUFA, especially if lambs are fed on pastures rather than concentrates. This study provides deeper insights in the clarification of the regulation of fatty acid biosynthesis and fat partitioning in tissues of ruminants with special emphasis on lambs.Relative gene expression differences between subcutaneous fat samples of Chilota lambs grazing on two different pasture types, Calafatal pasture (CP) and naturalized pasture (NP).

Defining the human adipose tissue proteome to reveal metabolic alterations in obesity.

White adipose tissue (WAT) has a major role in the progression of obesity. Here, we combined data from RNA-Seq and antibody-based immunohistochemistry to describe the normal physiology of human WAT obtained from three female subjects and explored WAT-specific genes by comparing WAT to 26 other major human tissues. Using the protein evidence in WAT, we validated the content of a genome-scale metabolic model for adipocytes. We employed this high-quality model for the analysis of subcutaneous adipose tissue (SAT) gene expression data obtained from subjects included in the Swedish Obese Subjects Sib Pair study to reveal molecular differences between lean and obese individuals. We integrated SAT gene expression and plasma metabolomics data, investigated the contribution of the metabolic differences in the mitochondria of SAT to the occurrence of obesity, and eventually identified cytosolic branched-chain amino acid (BCAA) transaminase 1 as a potential target that can be used for drug development. We observed decreased glutaminolysis and alterations in the BCAAs metabolism in SAT of obese subjects compared to lean subjects. We also provided mechanistic explanations for the changes in the plasma level of BCAAs, glutamate, pyruvate, and α-ketoglutarate in obese subjects. Finally, we validated a subset of our model-based predictions in 20 SAT samples obtained from 10 lean and 10 obese male and female subjects.