Alterations In Adipose Tissue Function Research Articles

Differential Modulation by Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) of Mesenteric Fat and Macrophages and T Cells in Adipose Tissue of Obese fa/fa Zucker Rats.

Polyunsaturated fatty acids (PUFAs) can alter adipose tissue function; however, the relative effects of plant and marine n3-PUFAs are less clear. Our objective was to directly compare the n3-PUFAs, plant-based α-linolenic acid (ALA) in flaxseed oil, and marine-based eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) in high-purity oils versus n6-PUFA containing linoleic acid (LA) for their effects on the adipose tissue and oral glucose tolerance of obese rats. Male fa/fa Zucker rats were assigned to faALA, faEPA, faDHA, and faLA groups and compared to baseline fa/fa rats (faBASE) and lean Zucker rats (lnLA). After 8 weeks, faEPA and faDHA had 11-14% lower body weight than faLA. The oral glucose tolerance and total body fat were unchanged, but faEPA had less mesenteric fat. faEPA and faDHA had fewer large adipocytes compared to faLA and faALA. EPA reduced macrophages in the adipose tissue of fa/fa rats compared to ALA and DHA, while faLA had the greatest macrophage infiltration. DHA decreased (~10-fold) T-cell infiltration compared to faBASE and faEPA, whereas faALA and faLA had an ~40% increase. The n3-PUFA diets attenuated tumour necrosis factor-α in adipose tissue compared to faBASE, while it was increased by LA in both genotypes. In conclusion, EPA and DHA target different aspects of inflammation in adipose tissue.

Short-term lingonberry feeding is associated with decreased insulin levels and altered adipose tissue function in high-fat diet fed C57BL/6J mice

• High-fat diet supplemented with Lingonberry reduces body weight gain in mice. • Adipocytes isolated from lingonberry-fed mice display increased lipolysis. • Mitochondrial dynamics are altered in adipose tissue from mice fed lingonberries. • Mice fed lingonberries have lower plasma insulin levels. Intact adipose tissue function is essential to maintain glucose and lipid homeostasis. To study the impact of altered adipose tissue function on whole-body metabolism, diet-induced obesity in mice is frequently used as a model organism. In the current study, we have examined health-promoting effects of a lingonberry supplemented diet. We found C57BL/6J mice fed a high-fat diet supplemented with lingonberry for 4 days to have significantly lowered body-weight gain, adipose tissue expansion, and reduced insulin levels, compared to mice fed an isocaloric high-fat diet. RNA-Seq analysis of epididymal adipose tissue revealed differential expression of genes related to mitochondria fission ( Mief1, Dnm1, Vps35, and Opa1 ). Further, we detected increased gene expression and phosphorylation of perilipin-1 (pS522), and increased lipolysis in primary adipocytes from lingonberry-fed mice. Together, these data pinpoint that beneficial effects of a lingonberry enriched diet are rapidly detectable and that the adipose tissue constitutes a target for these effects.

Non-alcoholic fatty liver disease in type 2 diabetes - A specific entity?

Individuals with obesity or type 2 diabetes (T2D) have an increased risk of developing non-alcoholic fatty liver disease (NAFLD). In insulin-resistant states, altered adipose tissue function may be the initial abnormality underlying NAFLD. Hepatic lipid oversupply interferes with insulin signalling and mitochondrial function. In obese individuals, adaptation of hepatic mitochondrial respiration fails with the progression of NAFLD and can activate pro-inflammatory pathways. T2D as well as type 1 diabetes are associated with altered hepatic mitochondrial function. Screening for NAFLD remains challenging especially in those with diabetes because liver enzymes are often in the normal range and the performance of NAFLD scores is limited. Patients with T2D and severe insulin-resistant diabetes (SIRD) have the highest prevalence of NAFLD at diagnosis and the greatest risk of progression. In this subgroup, the single-nucleotide-polymorphism (SNP) rs738409(G) of the patatin-like phospholipase domain-containing protein 3 (PNPLA3) gene is associated with high liver fat content and adipose tissue insulin resistance. This frequent SNP is also known to be associated with lean NAFLD so that genetic testing for this and other SNPs could improve future screening strategies to identify high-risk individuals. Although lifestyle modifications are effective, this approach is limited owing to difficulties with compliance and several classes of drugs are being tested to treat NAFLD. Antihyperglycaemic drugs such as glucagon-like peptide 1 receptor agonists (GLP-1 RA), sodium-glucose cotransporter 2 inhibitors (SGLT2i) and pioglitazone are promising and halt the progression of NAFLD. In conclusion, although NAFLD in diabetes may not be a separate entity, there are specific features to its pathogenesis and clinical management.

COL6A3 expression in adipose tissue cells is associated with levels of the homeobox transcription factor PRRX1

Fibrillar collagen COL6α3 in adipose tissue has been associated with obesity, inflammation, insulin resistance and cancer. We here aimed to identify novel transcriptional regulators of COL6A3 expression. Based on a transcriptome dataset of adipose tissue, we identified strong correlations for 56 genes with COL6A3 mRNA, including targets of TGF-β/SMAD signaling. Among the identified candidates, the homeobox transcription factor PRRX1 showed a particularly striking co-expression with COL6A3, validated across several different cohorts, including patients with extreme obesity, insulin sensitive and resistant obesity (subcutaneous and omental), after profound fat loss (subcutaneous), and lean controls (subcutaneous). In human and mouse adipose cells, PRRX1 knockdown reduced COL6A3 mRNA and PRRX1 overexpression transactivated a reporter construct with the endogenous human COL6A3 promoter. Stable PRRX1 overexpression in 3T3-L1 cells induced Col6a3 mRNA threefold specifically after adipogenic induction, whereas TGF-β1 treatment upregulated Col6a3 mRNA also in the preadipocyte state. Interestingly, pro-inflammatory stimulus (i.e., TNF-α treatment) decreased PRRX1-mediated Col6a3 transactivation and mRNA expression, supporting a role for this mechanism in the regulation of adipose tissue inflammation. In conclusion, we identified the homeobox factor PRRX1 as a novel transcriptional regulator associated with COL6A3 expression, providing new insight into the regulatory mechanisms of altered adipose tissue function in obesity and insulin resistance.

Impact of pesticide exposure on adipose tissue development and function.

Obesity is a leading cause of morbidity, mortality and health care expenditure whose incidence is rapidly rising across the globe. Although the cause of the obesity epidemic is typically viewed as a product of an increased availability of high calorie foods and/or a reduction in physical activity, there is mounting evidence that exposure to synthetic chemicals in our environment may play an important role. Pesticides, are a class of chemicals whose widespread use has coincided with the global rise of obesity over the past two decades. Importantly, given their lipophilic nature many pesticides have been shown to accumulate with adipose tissue depots, suggesting they may be disrupting the function of white adipose tissue (WAT), brown adipose tissue (BAT) and beige adipose tissue to promote obesity and metabolic diseases such as type 2 diabetes. In this review, we discuss epidemiological evidence linking pesticide exposure with body mass index (BMI) and the incidence of diabetes. We then review preclinical studies in rodent models which have directly evaluated the effects of different classes of insecticides and herbicides on obesity and metabolic dysfunction. Lastly, we review studies conducted in adipose tissue cells lines and the purported mechanisms by which pesticides may induce alterations in adipose tissue function. The review of the literature reveals major gaps in our knowledge regarding human exposure to pesticides and our understanding of whether physiologically relevant concentrations promote obesity and elicit alterations in key signaling pathways vital for maintaining adipose tissue metabolism.

Altered adipose tissue and adipocyte function in the pathogenesis of metabolic syndrome.

Over the past decade, great progress has been made in understanding the complexity of adipose tissue biology and its role in metabolism. This includes new insights into the multiple layers of adipose tissue heterogeneity, not only differences between white and brown adipocytes, but also differences in white adipose tissue at the depot level and even heterogeneity of white adipocytes within a single depot. These inter- and intra-depot differences in adipocytes are developmentally programmed and contribute to the wide range of effects observed in disorders with fat excess (overweight/obesity) or fat loss (lipodystrophy). Recent studies also highlight the underappreciated dynamic nature of adipose tissue, including potential to undergo rapid turnover and dedifferentiation and as a source of stem cells. Finally, we explore the rapidly expanding field of adipose tissue as an endocrine organ, and how adipose tissue communicates with other tissues to regulate systemic metabolism both centrally and peripherally through secretion of adipocyte-derived peptide hormones, inflammatory mediators, signaling lipids, and miRNAs packaged in exosomes. Together these attributes and complexities create a robust, multidimensional signaling network that is central to metabolic homeostasis.

Open Chromatin Profiling in Adipose Tissue Marks Genomic Regions with Functional Roles in Cardiometabolic Traits.

Identifying the regulatory mechanisms of genome-wide association study (GWAS) loci affecting adipose tissue has been restricted due to limited characterization of adipose transcriptional regulatory elements. We profiled chromatin accessibility in three frozen human subcutaneous adipose tissue needle biopsies and preadipocytes and adipocytes from the Simpson Golabi-Behmel Syndrome (SGBS) cell strain using an assay for transposase-accessible chromatin (ATAC-seq). We identified 68,571 representative accessible chromatin regions (peaks) across adipose tissue samples (FDR < 5%). GWAS loci for eight cardiometabolic traits were enriched in these peaks (P < 0.005), with the strongest enrichment for waist-hip ratio. Of 110 recently described cardiometabolic GWAS loci colocalized with adipose tissue eQTLs, 59 loci had one or more variants overlapping an adipose tissue peak. Annotated variants at the SNX10 waist-hip ratio locus and the ATP2A1-SH2B1 body mass index locus showed allelic differences in regulatory assays. These adipose tissue accessible chromatin regions elucidate genetic variants that may alter adipose tissue function to impact cardiometabolic traits.

Impact of HIV/simian immunodeficiency virus infection and viral proteins on adipose tissue fibrosis and adipogenesis

HIV-infected patients receiving antiretroviral treatment (ART) often present adipose tissue accumulation and/or redistribution. adipose tissue has been shown to be an HIV/SIV reservoir and viral proteins as Tat or Nef can be released by infected immune cells and exert a bystander effect on adipocytes or precursors. Our aim was to demonstrate that SIV/HIV infection per se could alter adipose tissue structure and/or function. Morphological and functional alterations of subcutaneous (SCAT) and visceral adipose tissue (VAT) were studied in SIV-infected macaques and HIV-infected ART-controlled patients. To analyze the effect of Tat or Nef, we used human adipose stem cells (ASCs) issued from healthy donors, and analyzed adipogenesis and extracellular matrix component production using two dimensional (2D) and three-dimensional (3D) culture models. Adipocyte size and index of fibrosis were determined on Sirius red-stained adipose tissue samples. Proliferating and adipocyte 2D-differentiating or 3D-differentiating ASCs were treated chronically with Tat or Nef. mRNA, protein expression and secretion were examined by RT-PCR, western-blot and ELISA. SCAT and VAT from SIV-infected macaques displayed small adipocytes, decreased adipogenesis and severe fibrosis with collagen deposition. SCAT and VAT from HIV-infected ART-controlled patients presented similar alterations. In vitro, Tat and/or Nef induced a profibrotic phenotype in undifferentiated ASCs and altered adipogenesis and collagen production in adipocyte-differentiating ASCs. We demonstrate here a specific role for HIV/SIV infection per se on adipose tissue fibrosis and adipogenesis, probably through the release of viral proteins, which could be involved in adipose tissue dysfunction contributing to cardiometabolic alterations of HIV-infected individuals.

Differential Transcription of CD95 in Abdominal and Lower‐Body Subcutaneous Fat Depot–Implications for Regional Differences in Adipose Tissue Function

BackgroundAbdominal (ABD) and lower‐body (LB) fat depots exert opposing effects on cardiometabolic risk factors. However, molecular mechanisms underlying these differences are not completely understood. Studies suggest an inflammatory role of CD95 in obesity‐associated adipose tissue inflammation and dysfunction. Also, leptin deficiency is associated with increased CD95 expression.ObjectiveTo examine the expression of CD95 in the ABD and LB fat depots and to investigate leptin‐dependent CD95 regulation.MethodsTranscription of CD95 and other adipokines was determined in paired subcutaneous abdominal (ABD) and lower‐body (femoral, LB) fat samples obtained from 29 healthy individuals (10 females, age: 29.4 ± 7.6 years, BMI: 24 ± 4.1 kg/m2). The underlying mechanisms and down‐stream effects of altered CD95 expression were evaluated using differentiated human white preadipocytes (dHWP).ResultsReduced mRNA expression of CD95 was apparent in adipose tissue obtained from LB fat depot [ABD: 4.30 (13.91 – 0.06), LB: 2.49 (10.88 – 0.04), p = 0.01]. mRNA expression of MCP1 [ABD: 0.51 (1.35 – 0.34), LB: 0.51 (1.21 – 0.28), p = 0.51], CCL5 [ABD: 6.60 (43.45 – 1.40), LB: 4.44 (11.28 – 1.27), p = 0.20], TNFα [ABD: 1.10 (6.14 – 0.03), LB: 0.07 (5.84 – 0.03), p = 0.30], and leptin [ABD: 21.86 (31.33 – 14.6), LB: 27.23 (41.69 – 20.35), p = 0.08] was not different between the two fat depots. A positive relationship between CD95 mRNA and other inflammatory cytokines was evident in both ABD (MCP1: ρ = 0.79, p &lt; 0.001; CCL5: ρ = 0.83, p &lt; 0.001; TNFα: ρ = 0.87, p &lt; 0.001) and LB fat depot (MCP1: ρ = 0.87, p &lt; 0.001; CCL5: ρ = 0.78, p &lt; 0.001; TNFα: ρ = 0.83, p &lt; 0.001). Furthermore, leptin‐dependent decreases in CD95 mRNA (p = 0.04) and protein expression (p = 0.03) was seen in dHWP. Also, 24 hour pre‐treatment of dHWP with leptin protected cells from FasL (p = 0.03) induced apoptosis.ConclusionsCompared to ABD adipose tissue, LB fat has reduced transcription of CD95. Additionally, expression of CD95 mRNA was associated with increased expression of inflammatory cytokines in both ABD and LB subcutaneous fat. Moreover, we show that leptin may mediate decreases in CD95 expression thereby protecting adipose tissue from FasL mediated apoptosis. Our studies suggest that the decreased CD95 mRNA expression in LB fat depot may be related to higher localized leptin expression and possibly contribute to depot specific alterations in adipose tissue function and consequent cardiometabolic risk.Support or Funding InformationPrachi Singh is supported by AHA grant‐in‐Aid 17GRNT33660138.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

HSD17B12 Is Essential for the Metabolic Homeostasis in Adult Mice

Hydroxysteroid 17‐beta dehydrogenase (HSD17B) enzymes have an important role in the regulation of sex steroid metabolism by catalyzing the conversion between 17‐keto and 17‐hydroxysteroids. In addition, some HSD17B enzymes are involved in lipid metabolism. Our data together with other previous studies suggest that HSD17B12 is involved in the elongation of very long chain fatty acids (VLCFAs), presumably in producing arachidonic acid. The enzyme presents with universal expression pattern both in human and mouse. Our previous studies have shown that the global knockout of Hsd17b12 gene in mice is embryonic lethal, which is likely due to its pivotal role in the elongation of VLCFAs during development. The aim of the present study was to determine the role of HSD17B12 at adulthood. We, thus, generated conditional Hsd17b12 knockout mice with exon 2 flanked by loxP sites. The gene was globally deleted by crossing the floxed mice with those expressing the tamoxifen‐inducible Cre recombinase in the Rosa26 locus (HSD17B12cKOrosa26 mice) and by providing tamoxifen treatment at the age of eight weeks. Interestingly, inducing the global gene deletion led to 20% reduction in body weight, associated with drastically reduced amount of both white and brown adipose tissue. Our results with indirect calorimetry showed that food intake and water consumption were dramatically reduced (44% and 65%, respectively) in HSD17B12cKOrosa26 mice, although the hypothalamic regulation of feeding behavior was intact. The loss of appetite might be a consequence of general indisposition of the animals, however, no differences in motor activity was observed between KO and control mice. To study whether the strong metabolic phenotype is caused by an altered adipose tissue function, we then generated an inducible, adipocyte‐specific Hsd17b12 KO model (HSD17B12cKOadipoq) by crossbreeding the floxed mice with those expressing the tamoxifen‐inducible Cre recombinase under adiponectin promoter (Adipoq‐cre/ERT2 mice). Surprisingly, the HSD17B12cKOadipoq mice were viable, presented with normal body weight, and were free of any obvious abnormalities. Because of the high hepatic expression of HSD17B12 in both human and mouse, we generated a liver‐specific knockout mouse by crossbreeding the floxed mouse strain with Albumin‐Cre mouse strain. These mice were viable but presented with lipid accumulation in the hepatocytes at a young age (2 months). The results indicate that HSD17B12 is essential for the metabolic homeostasis in adult mice, while the vital role of the enzyme in metabolic regulation is not due to the high HSD17B12 activity in the adipocytes or hepatocytes. Moreover, the hepatocyte‐specific deletion of Hsd17b12 leads to liver steatosis in mice.Support or Funding InformationThis research was funded by Sigrid Jusélius foundation, Academy of Finland and Drug Research Doctoral Program at the University of Turku.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

From White to Brown - Adipose Tissue Is Critical to the Extended Lifespan and Healthspan of Growth Hormone Mutant Mice.

Growth hormone (GH) is a metabolic hormone that has major functions in the liver, muscle, and adipose tissue (AT). In the past 20years, numerous studies have demonstrated that decreased growth hormone (GH) action is clearly linked to alterations in longevity. Therefore, it is not surprising that mechanisms underlying the extended longevity of GH-mutant animals include alterations in AT function. This Review aims to describe the basics of AT biology, GH secretion and action, and the effects of altered GH signaling in mice and humans. Lastly, this Review discusses the intersection of GH and AT, and how the influence of GH on AT may play a critical role in determining lifespan and healthspan.

Autophagy in Adipose Tissue Physiology and Pathophysiology.

Significance: Alterations in adipose tissue function have profound consequences on whole body energy homeostasis because this tissue is central for fat accumulation, energy expenditure, glucose and insulin metabolism, and hormonal regulation. With the obesity reaching epidemic proportions globally, it is important to understand the mechanisms leading to adipose tissue malfunction. Recent Advances: Autophagy has originally been viewed as an adaptive response to cellular stress, but in recent years this process was shown to regulate important cellular processes. In adipose tissue, autophagy is a key regulator of white adipose tissue (WAT) and brown adipose tissue (BAT) adipogenesis, and dysregulated autophagy impairs fat accumulation both in vitro and in vivo. Animal studies have also suggested an important role for autophagy and mitophagy during the transition from beige to white fat. Human studies have provided evidence for altered autophagy in WAT, and these alterations correlated with the degree of insulin resistance. Critical Issues: Despite these important advances in the study of autophagy in adipose tissue, we still do not understand the physiological role of autophagy in mature white and brown adipocytes. Furthermore, several human studies involving autophagy assessment were performed on whole adipose tissue, which complicates the interpretation of the results considering the cellular heterogeneity of this tissue. Future Directions: Future studies will undoubtedly expand our understanding of the role of autophagy in fully differentiated adipocytes, and uncover novel cross-talks between this tissue and other organs in regulating lipid metabolism, redox signaling, energy homeostasis, and insulin sensitivity.

Abstract 312: Cardiomyocyte-secreted Signaling Factors Modulate Adipocyte Differentiation And Function

Heart failure (HF) alters cardiomyocyte metabolism by altering energy substrate utilization and mitochondrial function, which has potential implications for global metabolic health. Recent studies demonstrated that cardiomyocyte-released signaling factors communicate with peripheral organ systems to alter metabolic function and that signaling pathways activated by HF control the release of these factors. However, the identity of these factors is still under investigation. Conditioned media (CM) collected from neonatal rat ventricular myocytes (NRVMs) was used to treat 3T3-L1 pre-adipocytes to 1) identify signaling molecules released by cardiomyocytes that could regulate global metabolic function and 2) determine how HF signaling pathways alter their release. NRVM-CM slowed adipocyte differentiation as measured by lipid accumulation using the fluorescent probe BODIPY 493/503 (57±8% decrease in normalized fluorescence compared to control media) and reduced the expression of adipocyte-related proteins. NRVM CM treatment also increased basal mitochondrial oxygen consumption (78 ± 3 vs 62±4 pmol/min) and maximal respiration (270±12 vs 220 ± 16 pmol/min) in mature adipocytes. CM protein fractionation revealed that released-factor activity was retained in &gt;100kDa fractions and this activity was abolished by trypsin digestion, suggesting a novel, high-MW cardiomyocyte-released signaling protein that targets adipocytes. To determine if NRVM-released factor activity is altered by HF signaling, the ability of G-protein kinase 2 (GRK2, upregulated by HF) signaling activity to alter NRVM-released factor activity was investigated. GRK2 overexpression in NRVMs increased the activity of this released-factor as measured by further decreased 3T3-L1 differentiation (lipid accumulation measured by BODIPY fluorescence was 70±8% compared to CM from GFP-overexpressing NRVMs), while overexpression of the GRK2 inhibitor βARKct increased adipocyte differentiation (140±13% compared to control NRVM-CM). These results suggest a novel, high-MW cardiomyocyte-released signaling protein under the control of HF signaling pathways communicates with adipocytes to alter adipose tissue function and potentially alter global metabolic function.

Abstract 432: Differential MicroRNA Expression in Subcutaneous Abdominal and Lower-body Fat Depots

Background: Abdominal fat elevates while lower-body (LB) fat diminishes cardiovascular risk. However, molecular mechanisms differentiating the two fat depots are not completely understood. MicroRNA (miRNA) are important regulators of gene expression with widespread effects on several proteins. Objective: To explore miRNA differences between the two fat depots using unbiased next-generation sequencing (NGS) approach. Methods: Total RNA isolated from paired subcutaneous (sc) fat tissue obtained from abdomen (ABD) and LB (femoral) region of 12 healthy subjects (7 male; age: 27 ± 5 years; BMI: 23.5 ± 3.2 kg/m 2 ) was used to quantify miRNA expression. Body fat distribution was determined using dual-energy X-ray absorptiometry and abdominal computed tomography scans. RNA was prepped using the NEBNext small RNA library prep kit and sequenced using Illumina HiSeq 2000. Raw sequence data were processed using CAP-miRSeq pipeline. miRNA expression between the two depots was evaluated using EdgeR. Relationship between miRNA and regional fat depots were examined using Spearman’s correlation. Adjusted or unadjusted P value &lt;0.05 was considered significant. Results: Using NGS, 383 ± 55 known miRNA with ≥5 raw reads were detected in the study samples. Principal component analysis including all miRNAs showed no any clear separation between ABD or LB fat tissue. However, 37 miRNAs were found to have altered expression in the two depots. miR-196a-5p (log2FC=1.138, p&lt;0.001), miR-146b-5p ( log2FC=1.388, p&lt;0.001), miR-1287 ( log2FC=1.059, p&lt;0.001), miR-1247-5p (1.002, p&lt;0.001), and miR-346 (log2FC =-1.240, p=0.002) were among the top five differentially expressed miRNA in ABD Vs. LB fat. Interestingly, ABD fat tissue expression of miR196a-5p (rho=-0.58, p=0.047) and miR146b-5p (rho=0.76, p=0.004) correlated with visceral fat while miR146b-5p (rho=0.66, p=0.02) and miR1287 (rho=0.79, p=0.002) correlated with ABD sc fat. Conclusions: Several miRNAs are differentially expressed between ABD and LB fat tissue which may partly contribute to depot specific alterations in adipose tissue function and consequent cardiometabolic risk. Furthermore, the associations between miRNA and regional fat depots suggest a functional role of these miRNA in fat distribution.

Chronic intrahypothalamic rather than subcutaneous liraglutide treatment reduces body weight gain and stimulates the melanocortin receptor system

Background:The GLP-1 receptor agonist liraglutide is marketed for obesity treatment where it induces body weight reduction possibly via the hypothalamus, which regulates energy homeostasis. In animal studies, acute liraglutide treatment triggers satiety, weight loss and activates thermogenesis in adipose tissue. However, the precise mechanisms how liraglutide affects in particular chronic weight loss are still under investigation.Objectives:We aimed to evaluate whether chronic hypothalamic or chronic subcutaneous administration of liraglutide induces sustained weight loss through altered adipose tissue function and to what extent hypothalamic neuronal appetite regulators are involved in the liraglutide-induced weight loss in healthy lean rats on a normal diet.Materials/Methods:We continuously administered liraglutide either intrahypothalamically (10 μg per day) or subcutaneously (200 μg kg−1 per day) for 28 days to lean Sprague Dawley rats (n=8 each). We assessed changes in body weight, adipose tissue mass, adipocyte size and adipose tissue volume in the abdominal region by using micro-CT. We analyzed genetic expression patterns of browning, thermogenic and adipocyte differentiation regulators in adipose tissues as well as particular neuronal appetite regulators in the hypothalamus.Results:Intrahypothalamic liraglutide administration induced an 8% body weight reduction at day 9 compared with the control group (P<0.01) and a 7% body weight loss at day 9 compared with subcutaneous liraglutide treatment (P<0.01), supported by a significant reduction in adipose tissue mass and volume with intrahypothalamic liraglutide administration (P<0.05). Our data show that chronic intrahypothalamic liraglutide treatment triggered an 18-fold induction of the hypothalamic mc4r gene (P<0.01) accompanied by a significant increase in circulating thyroxine (T4) levels (P<0.05).Conclusions:Chronic intrahypothalamic liraglutide administration resulted in a profound reduction in body weight and fat mass loss most likely mediated by the hypothalamic melanocortin system rather than by adipose tissue browning or improved thermogenesis.

Obesity and Cancer Mechanisms: Tumor Microenvironment and Inflammation.

Purpose There is growing evidence that inflammation is a central and reversible mechanism through which obesity promotes cancer risk and progression. Methods We review recent findings regarding obesity-associated alterations in the microenvironment and the local and systemic mechanisms through which these changes support tumor growth. Results Locally, hyperadiposity is associated with altered adipose tissue function, adipocyte death, and chronic low-grade inflammation. Most individuals who are obese harbor inflamed adipose tissue, which resembles chronically injured tissue, with immune cell infiltration and remodeling. Within this distinctly altered local environment, several pathophysiologic changes are found that may promote breast and other cancers. Consistently, adipose tissue inflammation is associated with a worse prognosis in patients with breast and tongue cancers. Systemically, the metabolic syndrome, including dyslipidemia and insulin resistance, occurs in the setting of adipose inflammation and operates in concert with local mechanisms to sustain the inflamed microenvironment and promote tumor growth. Importantly, adipose inflammation and its protumor consequences can be found in some individuals who are not considered to be obese or overweight by body mass index. Conclusion The tumor-promoting effects of obesity occur at the local level via adipose inflammation and associated alterations in the microenvironment, as well as systemically via circulating metabolic and inflammatory mediators associated with adipose inflammation. Accurately characterizing the obese state and identifying patients at increased risk for cancer development and progression will likely require more precise assessments than body mass index alone. Biomarkers of adipose tissue inflammation would help to identify high-risk populations. Moreover, adipose inflammation is a reversible process and represents a novel therapeutic target that warrants further study to break the obesity-cancer link.

Leptin intake in suckling rats restores altered T3 levels and markers of adipose tissue sympathetic drive and function caused by gestational calorie restriction

Maternal calorie restriction during gestation in rats has been associated with altered white adipose tissue (WAT) sympathetic innervation and function in offspring. Here, we aimed to investigate whether supplementation with oral leptin (a breast milk component) throughout the lactation period may revert the aforementioned adverse programming effects. Three groups of male and female rats were studied at the postnatal day 25: the offspring of control dams, the offspring of 20% calorie-restricted dams during pregnancy (CR) and CR rats supplemented with physiological doses of leptin throughout lactation (CR-Leptin). Tyrosine hydroxylase (TH) levels and its immunoreactive area, and mRNA expression levels of lipid metabolism-related genes and of deiodinase iodothyronine type II (Dio2) were determined in WAT. Triiodothyronine (T3) levels were determined in the blood. In CR males, leptin treatment restored the decreased TH levels and its immunoreactive area in WAT, and partially normalized expression levels of genes related to lipolysis and fatty acid oxidation (adipose triglyceride lipase, hormone-sensitive lipase, carnitine palmitoyltransferase 1b and peroxisome proliferator-activated receptor gamma coactivator 1-alpha). Leptin treatment also reverted the decreased T3 plasma levels and WAT lipoprotein lipase mRNA levels occurring in CR males and females, and the decreased Dio2 mRNA levels in CR females. Leptin supplementation throughout the lactation period reverts the malprogrammed effects on WAT structure and function induced by undernutrition during pregnancy. These findings support the relevance of the intake of leptin during lactation, bearing clear characteristics of essential nutrient, and provide a strategy to treat and/or prevent the programmed trend to obesity acquired by inadequate fetal nutrition.

Transgenic ω-3 PUFA enrichment alters morphology and gene expression profile in adipose tissue of obese mice: Potential role for protectins

ObjectiveDietary administration of ω-3 polyunsaturated fatty acids (PUFA) is often associated with altered adipose tissue (AT) morphology and/or function in obese mice. Yet, it is unclear whether this is an indirect consequence of reduced weight gain or results from direct actions of ω-3 PUFA. Here we studied the AT of high fat (HF)-fed fat-1 transgenic mice that convert endogenous ω-6 to ω-3 PUFA while maintaining equivalent fat accretion as their wild-type (WT) counterparts. Materials and methodsAdipocyte size profiling, Affymetrix microarray pathway analysis, qPCR and protectin identification and analysis were performed in epididymal AT from hemizygous fat-1(+/−) mice and their wild type littermates that had been fed a HF diet for 8weeks from 6weeks of age. ResultsDespite equivalent fat pad mass, we found that epididymal AT from HF-fed transgenic animals possesses fewer large and very large but more mid-size adipocytes compared to WT mice. In order to better understand the underlying mechanisms contributing to the observed alteration in adipocyte size we performed an Affymetrix microarray. Pathway analysis of these data highlighted adipogenesis, cholesterol biosynthesis, insulin signaling, prostaglandin synthesis/regulation and small ligand GPCRs as points where differentially expressed genes were significantly overrepresented. Observed changes were confirmed for four candidate genes: Cnr1, Cnr2, Faah and Pparg by qPCR. Finally we demonstrated that protectin DX is present in AT and that protectin DX and protectin D1 promote comparable PPARγ transcriptional activity. ConclusionsThese data provide unprecedented evidence that ω-3 PUFA coordinately regulate AT gene expression programs in a manner that is independent of restriction of weight gain or fat accrual and highlight an important influence of ω-3 PUFA on adipogenesis. Furthermore we provide primary evidence suggesting that protectins likely contribute to these effects via their influence on PPARγ.

Cardiovascular risk in Egyptian healthy consumers of different types of combined oral contraceptives pills: A comparative study.

This study aimed to evaluate the associated cardiovascular risk in Egyptian healthy consumers of different types of combined oral contraceptives pills (COCPs) via determination of lipids profiles, Castelli index I, leptin, adiponectin, and resistin concentrations as cardiovascular risk factors. In this cross-sectional study, the study groups consisted of control group that represented by 30 healthy married women who were not on any contraceptive mean or any hormonal therapy and had normal menstrual cycles, group two consisted of 30 women who were users of Levonorgesterl 0.15 mg plus Ethinylestradiol 0.03 mg as 21 days cycle, group three consisted of 30 women who were users of Gestodene 0.075 mg plus Ethinylestradiol 0.03 mg as 21 days cycle, and group four consisted of 30 women who were users of Drospirenone 3 mg plus Ethinylestradiol 0.03 mg as 21 days cycle. One-way analysis of variance followed by LSD post hoc test was used for comparison of variables. P value <0.05 was considered to be significant. The comparison of the studied groups revealed that COCPs containing levonorgestrel plus ethinylestradiol resulted in significantly lower adiponectin level, and significantly higher leptin and resistin levels with more atherogenic lipid profile presented by significantly higher LDL-C, significantly lower HDL-C concentrations, and significantly higher atherogenic index. Formulation containing ethinylestradiol combined with gestodene neither altered adipose tissue function nor showed deleterious effect on lipid panel. Formulation containing ethinylestradiol combined with drospirenone resulted in significantly higher HDL-C and adiponectin concentrations. In conclusion, the uptake of COCPs containing levonorgestrel plus ethinylestradiol is associated with high cardiovascular risk since this formulation showed significantly lower adiponectin concentration, significantly higher leptin, resistin, and atherogenic index as compared to other studied groups. By contrast, the formulations containing ethinylestradiol combined with third generation progestin gestodene or fourth generation progestin drospirenone are associated with low cardiovascular risk since they neither altered adipose tissue function nor impaired lipoprotein metabolism as experienced by their favorable effect on leptin, adiponectin, and resistin, with non-changed atherogenic index, higher HDL-C levels and lower LDL-C levels as compared to levonorgestrel plus ethinylestradiol formulation.

Adipobiology for Novel Therapeutic Approaches in Metabolic Syndrome

Obesity is dramatically increasing virtually worldwide, which has been linked to the rising prevalence of metabolic syndrome. Excess fat accumulation causes severe alterations in adipose tissue function. Actually, adipose tissue is now recognized as a major endocrine and secretory organ that releases a wide variety of signaling molecules (hormones, growth factors, cytokines, chemokines, etc.), the adipokines, which play central roles in the regulation of energy metabolism and homeostasis, immunity and inflammation. In addition, adipose tissue is no longer regarded as a passive lipid storage site but as a highly dynamic energy depot which stores excess energy during periods of positive energy balance and mobilizes it in periods of nutrient deficiency in a tightly regulated manner. Altered lipid release and adipokine production and signaling, as occurs in obesity, are linked to insulin resistance and the associated comorbidities of metabolic syndrome (dyslipidemia, hypertension), which confer an increased risk for the development of type 2 diabetes and cardiovascular disease. Here we summarize current knowledge on adipose tissue and review the contribution of novel techniques and experimental approaches in adipobiology to the identification of novel biomarkers and potential targets for dietary or pharmacological intervention to prevent and treat adipose tissue-associated diseases.