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Chang J, Wang Z, Hao Y, Song Y, Xia C. Calmodulin Contributes to Lipolysis and Inflammatory Responses in Clinical Ketosis Cows through the TLR4/IKK/NF-κB Pathway. Animals (Basel) 2024; 14:1678. [PMID: 38891725 PMCID: PMC11171032 DOI: 10.3390/ani14111678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/26/2024] [Accepted: 05/29/2024] [Indexed: 06/21/2024] Open
Abstract
Clinical ketosis is a detrimental metabolic disease in dairy cows, often accompanied by severe lipolysis and inflammation in adipose tissue. Our previous study suggested a 2.401-fold upregulation in the calmodulin (CaM) level in the adipose tissue of cows with clinical ketosis. Therefore, we hypothesized that CaM may regulate lipolysis and inflammatory responses in cows with clinical ketosis. To verify the hypothesis, we conducted a thorough veterinary assessment of clinical symptoms and serum β-hydroxybutyrate (BHB) concentration. Subsequently, we collected subcutaneous adipose tissue samples from six healthy and six clinically ketotic Holstein cows at 17 ± 4 days postpartum. Commercial kits were used to test the abundance of BHB, non-esterified fatty acid (NEFA), the liver function index (LFI), interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α). We found that cows with clinical ketosis exhibited higher levels of BHB, NEFA, LFI, IL-6, IL-1β, TNF-α, and lower glucose levels than healthy cows. Furthermore, the abundance of CaM, toll-like receptor 4 (TLR4), inhibitor of nuclear factor κB kinase subunit β (IKK), phosphorylated nuclear factor κB p65/nuclear factor κB p65 (p-NF-κB p65/NF-κB p65), adipose triacylglycerol lipase (ATGL), and phosphorylated hormone-sensitive lipase/hormone-sensitive lipase (p-HSL/HSL) was increased, while that of perilipin-1 (PLIN1) was decreased in the adipose tissue of cows with clinical ketosis. To investigate the mechanism underlying the responses, we isolated the primary bovine adipocytes from the adipose tissue of healthy cows and induced the inflammatory response mediated by TLR4/IKK/NF-κB p65 with lipopolysaccharide (LPS). Additionally, we treated the primary bovine adipocytes with CaM overexpression adenovirus and CaM small interfering RNA. In vitro, LPS upregulated the abundance of TLR4, IKK, p-NF-κB p65, ATGL, p-HSL/HSL, and CaM and downregulated PLIN1. Furthermore, CaM silencing downregulated the abundance of LPS-activated p-HSL/HSL, TLR4, IKK, and p-NF-κB p65 and upregulated PLIN1 in bovine adipocytes, except for ATGL. However, CaM overexpression upregulated the abundance of LPS-activated p-HSL/HSL, TLR4, IKK, and p-NF-κB p65 and downregulated PLIN1 expression in bovine adipocytes. These data suggest that CaM promotes lipolysis in adipocytes through HSL and PINL1 while activating the TLR4/IKK/NF-κB inflammatory pathway to stimulate an inflammatory response. There is a positive feedback loop between CaM, lipolysis, and inflammation. Inhibiting CaM may act as an adaptive mechanism to alleviate metabolic dysregulation in adipose tissue, thereby relieving lipolysis and inflammatory responses.
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Affiliation(s)
- Jinshui Chang
- College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, China; (J.C.); (Y.H.); (Y.S.)
| | - Zhijie Wang
- College of Veterinary Medicine, Southwest University, Chongqing 400715, China;
| | - Yu Hao
- College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, China; (J.C.); (Y.H.); (Y.S.)
| | - Yuxi Song
- College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, China; (J.C.); (Y.H.); (Y.S.)
| | - Cheng Xia
- College of Animal Science and Veterinary Medicine, Heilongjiang Bayi Agricultural University, Daqing 163319, China; (J.C.); (Y.H.); (Y.S.)
- Key Laboratory of Bovine Disease Control in Northeast China, Ministry of Agriculture and Rural Affairs, Daqing 163319, China
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Chirivi M, Contreras GA. Endotoxin-induced alterations of adipose tissue function: a pathway to bovine metabolic stress. J Anim Sci Biotechnol 2024; 15:53. [PMID: 38581064 PMCID: PMC10998405 DOI: 10.1186/s40104-024-01013-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 02/14/2024] [Indexed: 04/07/2024] Open
Abstract
During the periparturient period, dairy cows exhibit negative energy balance due to limited appetite and increased energy requirements for lactogenesis. The delicate equilibrium between energy availability and expenditure puts cows in a state of metabolic stress characterized by excessive lipolysis in white adipose tissues (AT), increased production of reactive oxygen species, and immune cell dysfunction. Metabolic stress, especially in AT, increases the risk for metabolic and inflammatory diseases. Around parturition, cows are also susceptible to endotoxemia. Bacterial-derived toxins cause endotoxemia by promoting inflammatory processes and immune cell infiltration in different organs and systems while impacting metabolic function by altering lipolysis, mitochondrial activity, and insulin sensitivity. In dairy cows, endotoxins enter the bloodstream after overcoming the defense mechanisms of the epithelial barriers, particularly during common periparturient conditions such as mastitis, metritis, and pneumonia, or after abrupt changes in the gut microbiome. In the bovine AT, endotoxins induce a pro-inflammatory response and stimulate lipolysis in AT, leading to the release of free fatty acids into the bloodstream. When excessive and protracted, endotoxin-induced lipolysis can impair adipocyte's insulin signaling pathways and lipid synthesis. Endotoxin exposure can also induce oxidative stress in AT through the production of reactive oxygen species by inflammatory cells and other cellular components. This review provides insights into endotoxins' impact on AT function, highlighting the gaps in our knowledge of the mechanisms underlying AT dysfunction, its connection with periparturient cows' disease risk, and the need to develop effective interventions to prevent and treat endotoxemia-related inflammatory conditions in dairy cattle.
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Affiliation(s)
- Miguel Chirivi
- Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI, USA
| | - G Andres Contreras
- Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI, USA.
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Reyes-Farias M, Fernández-García P, Corrales P, González L, Soria-Gondek A, Martínez E, Pellitero S, Tarascó J, Moreno P, Sumoy L, Medina-Gómez G, Sánchez-Infantes D, Herrero L. Interleukin-16 is increased in obesity and alters adipogenesis and inflammation in vitro. Front Endocrinol (Lausanne) 2024; 15:1346317. [PMID: 38544694 PMCID: PMC10965774 DOI: 10.3389/fendo.2024.1346317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 02/23/2024] [Indexed: 04/04/2024] Open
Abstract
Introduction Obesity is a chronic condition associated with low-grade inflammation mainly due to immune cell infiltration of white adipose tissue (WAT). WAT is distributed into two main depots: subcutaneous WAT (sWAT) and visceral WAT (vWAT), each with different biochemical features and metabolic roles. Proinflammatory cytokines including interleukin (IL)-16 are secreted by both adipocytes and infiltrated immune cells to upregulate inflammation. IL-16 has been widely studied in the peripheral proinflammatory immune response; however, little is known about its role in adipocytes in the context of obesity. Aim & Methods We aimed to study the levels of IL-16 in WAT derived from sWAT and vWAT depots of humans with obesity and the role of this cytokine in palmitate-exposed 3T3-L1 adipocytes. Results The results demonstrated that IL-16 expression was higher in vWAT compared with sWAT in individuals with obesity. In addition, IL-16 serum levels were higher in patients with obesity compared with normal-weight individuals, increased at 6 months after bariatric surgery, and at 12 months after surgery decreased to levels similar to before the intervention. Our in vitro models showed that IL-16 could modulate markers of adipogenesis (Pref1), lipid metabolism (Plin1, Cd36, and Glut4), fibrosis (Hif1a, Col4a, Col6a, and Vegf), and inflammatory signaling (IL6) during adipogenesis and in mature adipocytes. In addition, lipid accumulation and glycerol release assays suggested lipolysis alteration. Discussion Our results suggest a potential role of IL-16 in adipogenesis, lipid and glucose homeostasis, fibrosis, and inflammation in an obesity context.
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Affiliation(s)
- Marjorie Reyes-Farias
- Endocrinology department, Germans Trias i Pujol Research Institute (IGTP), Badalona, Spain
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Institute of Biomedicine of the University of Barcelona (IBUB), Universitat de Barcelona (UB), Barcelona, Spain
| | | | - Patricia Corrales
- Department of Basic Health Sciences, University Rey Juan Carlos (URJC), Madrid, Spain
| | - Lorena González
- Endocrinology department, Germans Trias i Pujol Research Institute (IGTP), Badalona, Spain
| | - Andrea Soria-Gondek
- Pediatric Surgery Department, Hospital Universitari Germans Trias i Pujol, Badalona, Spain
| | - Ester Martínez
- Department of Basic Health Sciences, University Rey Juan Carlos (URJC), Madrid, Spain
| | - Silvia Pellitero
- Endocrinology and Nutrition Department, Institute Research and Hospital Germans Trias i Pujol, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Jordi Tarascó
- General Surgery Department, Hospital Universitari Germans Trias i Pujol, Badalona, Spain
| | - Pau Moreno
- General Surgery Department, Hospital Universitari Germans Trias i Pujol, Badalona, Spain
| | - Lauro Sumoy
- Endocrinology department, Germans Trias i Pujol Research Institute (IGTP), Badalona, Spain
| | - Gema Medina-Gómez
- Department of Basic Health Sciences, University Rey Juan Carlos (URJC), Madrid, Spain
| | - David Sánchez-Infantes
- Department of Basic Health Sciences, University Rey Juan Carlos (URJC), Madrid, Spain
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Laura Herrero
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Institute of Biomedicine of the University of Barcelona (IBUB), Universitat de Barcelona (UB), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
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Machado H, Hofer P, Zechner R, Smith TK, Figueiredo LM. Adipocyte lipolysis protects mice against Trypanosoma brucei infection. Nat Microbiol 2023; 8:2020-2032. [PMID: 37828246 PMCID: PMC10627827 DOI: 10.1038/s41564-023-01496-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Accepted: 09/11/2023] [Indexed: 10/14/2023]
Abstract
Trypanosoma brucei causes African trypanosomiasis, colonizing adipose tissue and inducing weight loss. Here we investigated the molecular mechanisms responsible for adipose mass loss and its impact on disease pathology. We found that lipolysis is activated early in infection. Mice lacking B and T lymphocytes fail to upregulate adipocyte lipolysis, resulting in higher fat mass retention. Genetic ablation of the rate-limiting adipose triglyceride lipase specifically from adipocytes (AdipoqCre/+-Atglfl/fl) prevented the stimulation of adipocyte lipolysis during infection, reducing fat mass loss. Surprisingly, these mice succumbed earlier and presented a higher parasite burden in the gonadal adipose tissue, indicating that host lipolysis limits parasite growth. Consistently, free fatty acids comparable with those of adipose interstitial fluid induced loss of parasite viability. Adipocyte lipolysis emerges as a mechanism controlling local parasite burden and affecting the loss of fat mass in African trypanosomiasis.
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Affiliation(s)
- Henrique Machado
- Instituto de Medicina Molecular-João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Peter Hofer
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
- Field of Excellence BioHealth, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Terry K Smith
- School of Biology, Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
| | - Luísa M Figueiredo
- Instituto de Medicina Molecular-João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
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Yasuda D, Hamano F, Masuda K, Dahlström M, Kobayashi D, Sato N, Hamakubo T, Shimizu T, Ishii S. Inverse agonism of lysophospholipids with cationic head groups at Gi-coupled receptor GPR82. Eur J Pharmacol 2023; 954:175893. [PMID: 37392830 DOI: 10.1016/j.ejphar.2023.175893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 06/20/2023] [Accepted: 06/28/2023] [Indexed: 07/03/2023]
Abstract
GPR82 is an orphan G protein-coupled receptor (GPCR) that has been implicated in lipid storage in mouse adipocytes. However, the intracellular signaling as well as the specific ligands of GPR82 remain unknown. GPR82 is closely related to GPR34, a GPCR for the bioactive lipid molecule lysophosphatidylserine. In this study, we screened a lipid library using GPR82-transfected cells to search for ligands that act on GPR82. By measuring cyclic adenosine monophosphate levels, we found that GPR82 is an apparently constitutively active GPCR that leads to Gi protein activation. In addition, edelfosine (1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphocholine), an artificial lysophospholipid with a cationic head group that exerts antitumor activity, inhibited the Gi protein activation by GPR82. Two endogenous lysophospholipids with cationic head groups, lysophosphatidylcholine (1-oleoyl-sn-glycero-3-phosphocholine) and lysophosphatidylethanolamine (1-oleoyl-sn-glycero-3-phosphoethanolamine), also exhibited GPR82 inhibitory activity, albeit weaker than edelfosine. Förster resonance energy transfer imaging analysis consistently demonstrated that Gi protein-coupled GPR82 has an apparent constitutive activity that is edelfosine-sensitive. Consistent data were obtained from GPR82-mediated binding analysis of guanosine-5'-O-(3-thiotriphosphate) to cell membranes. Furthermore, in GPR82-transfected cells, edelfosine inhibited insulin-induced extracellular signal-regulated kinase activation, like compounds that function as inverse agonists at other GPCRs. Therefore, edelfosine is likely to act as an inverse agonist of GPR82. Finally, GPR82 expression inhibited adipocyte lipolysis, which was abrogated by edelfosine. Our findings suggested that the cationic lysophospholipids edelfosine, lysophosphatidylcholine and lysophosphatidylethanolamine are novel inverse agonists for Gi-coupled GPR82, which is apparently constitutively active, and has the potential to exert lipolytic effects through GPR82.
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Affiliation(s)
- Daisuke Yasuda
- Department of Immunology, Graduate School of Medicine, Akita University, Akita, Japan
| | - Fumie Hamano
- Life Sciences Core Facility, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kazuyuki Masuda
- Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | | | - Daiki Kobayashi
- Department of Immunology, Graduate School of Medicine, Akita University, Akita, Japan
| | - Nana Sato
- Department of Immunology, Graduate School of Medicine, Akita University, Akita, Japan
| | - Takao Hamakubo
- Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Takao Shimizu
- Department of Lipid Life Science, National Center for Global Health and Medicine, Tokyo, Japan; Institute of Microbial Chemistry, Tokyo, Japan
| | - Satoshi Ishii
- Department of Immunology, Graduate School of Medicine, Akita University, Akita, Japan.
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Yang J, He J, Feng Y, Xiang M. Obesity contributes to hepatocellular carcinoma development via immunosuppressive microenvironment remodeling. Front Immunol 2023; 14:1166440. [PMID: 37266440 PMCID: PMC10231659 DOI: 10.3389/fimmu.2023.1166440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 05/05/2023] [Indexed: 06/03/2023] Open
Abstract
It is generally recognized that the initiation of obesity-related hepatocellular carcinoma (HCC) is closely associated with hepatic inflammation. However, the paradoxical role of inflammation in the initiation and progression of HCC is highlighted by the fact that the inflammatory HCC is accompanied by significant immune effector cells infiltration compared to non-inflammatory HCC and HCC with enhanced immune response exhibits better survival. Importantly, the cancer progression has been primarily attributed to the immunosuppression, which can also be induced by obesity. Furthermore, the increased risk of viral infection and thus viral-HCC in obese individuals supports the view that obesity contributes to HCC via immunosuppression. Here, we have reviewed the various mechanisms responsible for obesity-induced tumor immune microenvironment and immunosuppression in obesity-related HCC. We highlight that the obesity-induced immunosuppression originates from lipid disorder as well as metabolic reprogramming and propose potential therapeutic strategy for HCC based on the current success of immunotherapy.
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Muskat A, Pirtle M, Kost Y, McLellan BN, Shinoda K. The Role of Fat Reducing Agents on Adipocyte Death and Adipose Tissue Inflammation. Front Endocrinol (Lausanne) 2022; 13:841889. [PMID: 35399925 PMCID: PMC8988282 DOI: 10.3389/fendo.2022.841889] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 02/28/2022] [Indexed: 01/02/2023] Open
Abstract
Deoxycholic Acid (DCA), which is an FDA-approved compound for the reduction of submental fat, has evolved through an unanticipated and surprising sequence of events. Initially, it was used as a solvent for Phosphatidylcholine (PDC), which was thought to promote lipolysis, but it was later proven to be the bioactive component of the formula and is currently widely used as Kybella. It has also been used off-label to treat other types of fat deposits like lipomas, HIV lipodystrophy, and excess orbital fat. Despite widespread clinical use, there has been no consensus clarifying the mechanisms of DCA and PDC alone or in combination. Furthermore, despite PDC's removal from the FDA-approved formula, some studies do suggest it plays an important role in fat reduction. To provide some clarity, we conducted a PubMed search and reviewed 41 articles using a comprehensive list of terms in three main categories, using the AND operator: 1) Phosphatidylcholines 2) Deoxycholic Acid, and 3) Lipoma. We isolated articles that studied PDC, DCA, and a PDC/DCA compound using cell biology, molecular and genetic techniques. We divided relevant articles into those that studied these components using histologic techniques and those that utilized specific cell death and lipolysis measurement techniques. Most morphologic studies indicated that PDC/DCA, DCA, and PDC, all induce some type of cell death with accompanying inflammation and fibrosis. Most morphologic studies also suggest that PDC/DCA and DCA alone are non-selective for adipocytes. Biochemical studies describing PDC and DCA alone indicate that DCA acts as a detergent and rapidly induces necrosis while PDC induces TNF-α release, apoptosis, and subsequent enzymatic lipolysis after at least 24 hours. Additional papers have suggested a synergistic effect between the two compounds. Our review integrates the findings of this growing body of literature into a proposed mechanism of fat reduction and provides direction for further studies.
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Affiliation(s)
- Ahava Muskat
- Department of Medicine, Division of Dermatology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Megan Pirtle
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Yana Kost
- Department of Medicine, Division of Dermatology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Beth N. McLellan
- Department of Medicine, Division of Dermatology, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Kosaku Shinoda
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, United States
- Department of Medicine, Division of Endocrinology & Diabetes, Albert Einstein College of Medicine, Bronx, NY, United States
- Albert Einstein College of Medicine, Fleischer Institute for Diabetes and Metabolism, Bronx, NY, United States
- *Correspondence: Kosaku Shinoda,
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5 α,6 α-Epoxyphytosterols and 5 α,6 α-Epoxycholesterol Increase Nitrosative Stress and Inflammatory Cytokine Production in Rats on Low-Cholesterol Diet. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:4751803. [PMID: 32587660 PMCID: PMC7298340 DOI: 10.1155/2020/4751803] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 05/26/2020] [Indexed: 11/18/2022]
Abstract
Objective Oxidized cholesterol derivatives are compounds with proven atherogenic and mutagenic effects. However, little is known about the effect of oxidized plant sterol derivatives (oxyphytosterols), whose structure is similar to the one of oxycholesterols. Our previous studies indicate that they have a similar profile of action, e.g., both exacerbate disorder of lipid metabolism and oxidative stress in experimental animals. The aim of the present study was to assess the effect of epoxycholesterol and epoxyphytosterols (mainly sitosterol) on the severity of nitrosative stress and the concentration of selected proinflammatory cytokines in blood and liver tissue of rats on a low-cholesterol diet. Material and Methods. Forty-five male Wistar rats were fed with feed containing 5α,6α-epoxyphytosterols (ES group, n: 15), 5α,6α-epoxycholesterol (ECh group, n: 15), and oxysterol-free feed (C group, n: 15) for 90 days (daily dose of oxysterols: 10 mg/kg). At the end of the experiment, nitrotyrosine, TNF-α, IL-1β, IL-6, and lipid metabolism parameters were determined in blood serum. Furthermore, nitrotyrosine, TNF-α, cholesterol, and triglyceride content were determined in liver homogenates. Results Serum nitrotyrosine, IL-1β, and TNF-α concentrations as well as TNF-α content in the liver were significantly higher in both groups exposed to oxysterols (ECh and ES groups) as compared to the C group. The serum IL-6 level and nitrotyrosine content in the liver were significantly higher in the ECh group, as compared to the C and ES groups. There was evidence to support the dyslipidemic effect of studied compounds. Conclusions The results indicate that oxidized plant sterols have a similar toxicity profile to that of oxycholesterols, including nitrosative stress induction, proinflammatory effect, and impaired lipid metabolism.
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Ye L, Cao Z, Lai X, Shi Y, Zhou N. Niacin Ameliorates Hepatic Steatosis by Inhibiting De Novo Lipogenesis Via a GPR109A-Mediated PKC-ERK1/2-AMPK Signaling Pathway in C57BL/6 Mice Fed a High-Fat Diet. J Nutr 2020; 150:672-684. [PMID: 31858105 DOI: 10.1093/jn/nxz303] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 10/18/2019] [Accepted: 11/19/2019] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in the world. Hepatic de novo lipogenesis (DNL) has been suggested to contribute to the pathogenesis of NAFLD. Recent studies have demonstrated that niacin (NA) modulates hepatic DNL through GPR109A. However, the underlying mechanism remains largely unknown. OBJECTIVES This study aims to elucidate the potential molecular mechanism by which GPR109A inhibits hepatic DNL. METHODS C57BL/6 wild-type (WT) and Gpr109a knockout (KO) mice (male, 5 wk old) were fed a high-fat diet (60% energy from fat) firstly for 6 wk to generate a diet-induced obese model. Subsequently, they were randomly divided into 4 groups for the next 8-9 wk: WT mice with oral water [WT + vehile (VE)], WT mice with oral NA (50 mM, dissolved in water) (WT + NA), KO mice with oral water (KO + VE), and KO mice with oral NA (50 mM) (KO + NA). Mechanisms were examined in HepG2 cells. Body composition, liver histology, biomarkers of hepatic function, lipid accumulation, and lipid synthesis signals in HepG2 cells were measured. RESULTS Upon activation, GPR109A apparently protected against obesity and hepatic steatosis (P < 0.05). The concentrations of hepatic Tnf-α in the WT + NA group were about 50% of those in the WT + VE group (P < 0.05). The activities of serum alanine transaminase and aspartate transaminase were 26.7% and 53.5% lower in the WT + NA group than in the WT + VE group, respectively (P < 0.05). In HepG2 cells, activation of GPR109A resulted in remarkable inhibition of oleic acid-induced lipid accumulation via a protein kinase C-extracellular signal-regulated kinase-1/2-AMP-activated protein kinase signaling pathway. CONCLUSIONS NA inhibits hepatic lipogenesis in C57BL/6 mice through a GPR109A-mediated signaling pathway, consistent with the mechanistic studies in HepG2 cells, suggesting its potential for treatment of NAFLD and other fatty liver diseases.
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Affiliation(s)
- Lingyan Ye
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Zheng Cao
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiangru Lai
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ying Shi
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Naiming Zhou
- Institute of Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
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Tougaard P, Martinsen LO, Lützhøft DO, Jensen HE, Flethøj M, Vandenabeele P, Pedersen AE, Skov S, Hansen AK, Hansen CHF. TL1A regulates adipose-resident innate lymphoid immune responses and enables diet-induced obesity in mice. Int J Obes (Lond) 2020; 44:1062-1074. [PMID: 32001795 DOI: 10.1038/s41366-020-0539-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 01/07/2020] [Accepted: 01/16/2020] [Indexed: 12/17/2022]
Abstract
BACKGROUND/OBJECTIVES TL1A is a pro-inflammatory cytokine that is homologous to TNFα and connected with the development of several chronic inflammatory disorders. The preliminary results of this study indicated reduced fat accumulation in 9-month-old TL1A-deficient mice at steady state. Thus, the objective was to investigate whether TL1A-deficient mice are resistant to the development of high-fat (HF) diet-induced obesity and to investigate the impact on lymphocyte infiltration in adipose tissue. METHODS TL1A-deficient and TL1A-sufficient male BALB/cJ littermate mice were fed a 60% HF diet or a 10% low-fat control diet for 22 weeks. Mouse body composition and weight were monitored, and tissues were processed and evaluated by flow cytometry, qPCR, and histology. RESULTS In this study, the TL1A-deficient HF-diet-fed mice had reduced whole-body weight gain, which was directly explained by a corresponding fat mass reduction (average 37.2%), compared with that of their TL1A-sufficient littermates. Despite previous data showing marked changes in the gut microbial community, TL1A-deficient GF mice also displayed reduced adiposity. Furthermore, the TL1A-deficient mice were resistant to hepatic steatosis and were shown to have improved glucose tolerance, as determined by oral glucose tolerance test (OGTT), and greater insulin sensitivity. In the epididymal white adipose tissue (eWAT), TL1A deficiency in HF-diet-fed mice resulted in a reduced abundance of IL-18Ra+ type-1 ILCs and γδT cells as well as markedly reduced expression of the mitochondria-regulating genes Ucp1, Ucp2, Ucp3, and Prdm16. Finally, to investigate the link of TL1A to obesity in humans, we identified a noncoding polymorphism (rs4979453) close to the TL1A locus that is associated with waist circumference in men (p = 0.00096, n = 60586). CONCLUSIONS These findings indicate that TL1A plays an important role in regulating adipose tissue mass and that this role is independent of the gut microbiota. Furthermore, we show that TL1A regulates adipose-resident innate lymphocytes and mitochondria-mediated oxidative stress in eWAT.
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Affiliation(s)
- Peter Tougaard
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, København, Denmark. .,Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, København, Denmark. .,Molecular Signaling and Cell Death Unit, VIB-Ugent Center for Inflammation Research, Flanders Institute for Biotechnology, Ghent, Belgium. .,Department for Biomedical Molecular Biology, Ghent University, Ghent, Belgium.
| | - Louise Otterstrøm Martinsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, København, Denmark
| | - Ditte Olsen Lützhøft
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, København, Denmark
| | - Henrik Elvang Jensen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, København, Denmark
| | - Mette Flethøj
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, København, Denmark
| | - Peter Vandenabeele
- Molecular Signaling and Cell Death Unit, VIB-Ugent Center for Inflammation Research, Flanders Institute for Biotechnology, Ghent, Belgium.,Department for Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Anders Elm Pedersen
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, København, Denmark.,Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, København, Denmark
| | - Søren Skov
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, København, Denmark
| | - Axel Kornerup Hansen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, København, Denmark
| | - Camilla Hartmann Friis Hansen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, København, Denmark
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11
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Funcke JB, Scherer PE. Beyond adiponectin and leptin: adipose tissue-derived mediators of inter-organ communication. J Lipid Res 2019; 60:1648-1684. [PMID: 31209153 PMCID: PMC6795086 DOI: 10.1194/jlr.r094060] [Citation(s) in RCA: 176] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 06/17/2019] [Indexed: 01/10/2023] Open
Abstract
The breakthrough discoveries of leptin and adiponectin more than two decades ago led to a widespread recognition of adipose tissue as an endocrine organ. Many more adipose tissue-secreted signaling mediators (adipokines) have been identified since then, and much has been learned about how adipose tissue communicates with other organs of the body to maintain systemic homeostasis. Beyond proteins, additional factors, such as lipids, metabolites, noncoding RNAs, and extracellular vesicles (EVs), released by adipose tissue participate in this process. Here, we review the diverse signaling mediators and mechanisms adipose tissue utilizes to relay information to other organs. We discuss recently identified adipokines (proteins, lipids, and metabolites) and briefly outline the contributions of noncoding RNAs and EVs to the ever-increasing complexities of adipose tissue inter-organ communication. We conclude by reflecting on central aspects of adipokine biology, namely, the contribution of distinct adipose tissue depots and cell types to adipokine secretion, the phenomenon of adipokine resistance, and the capacity of adipose tissue to act both as a source and sink of signaling mediators.
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Affiliation(s)
- Jan-Bernd Funcke
- Touchstone Diabetes Center, University of Texas Southwestern Medical Center, Dallas, TX
| | - Philipp E Scherer
- Touchstone Diabetes Center, University of Texas Southwestern Medical Center, Dallas, TX
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12
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Chan CC, Damen MSMA, Alarcon PC, Sanchez-Gurmaches J, Divanovic S. Inflammation and Immunity: From an Adipocyte's Perspective. J Interferon Cytokine Res 2019; 39:459-471. [PMID: 30920343 DOI: 10.1089/jir.2019.0014] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Comprehension of adipocyte function has evolved beyond a long-held belief of their inert nature, as simple energy storing and releasing cells. Adipocytes, including white, brown, and beige, are capable mediators of global metabolic health, but their intersection with inflammation is a budding field of exploration. Evidence hints at a reciprocal relationship adipocytes share with immune cells. Adipocyte's capacity to behave in an "immune-like" manner and ability to sense inflammatory cues that subsequently alter core adipocyte function might play an important role in shaping immune responses. Clarifying this intricate relationship could uncover previously underappreciated contribution of adipocytes to inflammation-driven human health and disease. In this review, we highlight the potential of largely underappreciated adipocyte "immune-like" function and how it may contribute to inflammation, immunity, and pathology of various diseases.
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Affiliation(s)
- Calvin C Chan
- 1Medical Scientist Training Program, Immunology Graduate Program, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio.,2Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio.,3Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Michelle S M A Damen
- 2Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio.,3Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Pablo C Alarcon
- 1Medical Scientist Training Program, Immunology Graduate Program, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio.,2Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio.,3Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Joan Sanchez-Gurmaches
- 2Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio.,4Division of Endocrinology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,5Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Senad Divanovic
- 1Medical Scientist Training Program, Immunology Graduate Program, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, Ohio.,2Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio.,3Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.,6Division of Center for Inflammation and Tolerance, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
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13
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Yang R, Guan MJ, Zhao N, Li MJ, Zeng T. Roles of extrahepatic lipolysis and the disturbance of hepatic fatty acid metabolism in TNF-α -induced hepatic steatosis. Toxicology 2018; 411:172-180. [PMID: 30359672 DOI: 10.1016/j.tox.2018.10.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/16/2018] [Accepted: 10/20/2018] [Indexed: 12/20/2022]
Abstract
Our previous study showed that both Kupffer cell eliminator (GdCl3) and tumor necrosis factor α (TNF-α) receptor antagonist (etanercept) could partially attenuate binge drinking-induced liver steatosis. Herein, we extended the study by directly investigating the roles of TNF-α on the hepatic fat levels in mice and in HepG2 cells, and explored the underlying mechanisms. SPF male ICR mice were exposed to TNF-α (0.166 mg/kg body weight) with or without phenylisopropyl adenosine (PIA, an anti-lipolytic drug) for 1.5, 3, 6, and 24 h. We found that TNF-α treatment resulted in hepatic triglyceride (TG) elevation at 6 h time point, which was blocked by PIA. TNF-α led to the activation of extrahepatic lipolysis demonstrated by the increase of serum free fatty acid (FFA) level, and the increased protein levels of adipose triglyceride lipase (ATGL) and phosphorylated hormone-sensitive lipase (HSL) in mice epididymal adipose tissues, but had no significant effects on the protein levels of sterol regulatory element binding protein 1c (SREBP-1c) and peroxisomal proliferator activation receptor α (PPAR-α) in mice liver. The in vitro study showed TNF-α treatment could not result in elevation of TG in HepG2 cells, although it indeed brought about a slight activation of SREBP-1c. These results support the hypothesis that TNF-α might make a small contribution to ethanol-induced fatty liver by stimulating extrahepatic lipolysis.
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Affiliation(s)
- Rui Yang
- Institute of Toxicology, School of Public Health, Shandong University, 44 Wenhua West Road, Shandong Province, Jinan City, 250012, PR China
| | - Min-Jie Guan
- Institute of Toxicology, School of Public Health, Shandong University, 44 Wenhua West Road, Shandong Province, Jinan City, 250012, PR China
| | - Ning Zhao
- Institute of Toxicology, School of Public Health, Shandong University, 44 Wenhua West Road, Shandong Province, Jinan City, 250012, PR China
| | - Ming-Jun Li
- Institute of Toxicology, School of Public Health, Shandong University, 44 Wenhua West Road, Shandong Province, Jinan City, 250012, PR China
| | - Tao Zeng
- Institute of Toxicology, School of Public Health, Shandong University, 44 Wenhua West Road, Shandong Province, Jinan City, 250012, PR China.
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14
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Tyrosine kinase inhibitors of Ripk2 attenuate bacterial cell wall-mediated lipolysis, inflammation and dysglycemia. Sci Rep 2017; 7:1578. [PMID: 28484277 PMCID: PMC5431485 DOI: 10.1038/s41598-017-01822-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 03/31/2017] [Indexed: 01/01/2023] Open
Abstract
Inflammation underpins aspects of insulin resistance and dysglycemia. Microbiota-derived cell wall components such as muropeptides or endotoxin can trigger changes in host immunity and metabolism. Specific peptidoglycan motifs promote metabolic tissue inflammation, lipolysis and insulin resistance via Nucleotide-binding oligomerization domain-containing protein 1 (Nod1). Receptor-interacting serine/threonine-protein kinase 2 (Ripk2) mediates Nod1-induced immunity, but the role of Ripk2 in metabolism is ill-defined. We hypothesized that Ripk2 was required for Nod1-mediated inflammation, lipolysis and dysglycemia. This is relevant because certain tyrosine kinase inhibitors (TKIs) inhibit Ripk2 and there is clinical evidence of TKIs lowering inflammation and blood glucose. Here, we showed that only a subset of TKIs known to inhibit Ripk2 attenuated Nod1 ligand-mediated adipocyte lipolysis. TKIs that inhibit Ripk2 decreased cytokine responses induced by Nod1-activating peptidoglycan, but not endotoxin in both metabolic and immune cells. Pre-treatment of adipocytes or macrophages with the TKI gefitinib inhibited Nod1-induced Cxcl1 and Il-6 secretion. Furthermore, treatment of mice with gefitinib prevented Nod1-induced glucose intolerance in vivo. Ripk2 was required for these effects on inflammation and metabolism, since Nod1-mediated cytokine and blood glucose changes were absent in Ripk2−/− mice. Our data show that specific TKIs used in cancer also inhibit Nod1-Ripk2 immunometabolism responses indicative of metabolic disease.
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15
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Decaffeinated green tea extract rich in epigallocatechin-3-gallate improves insulin resistance and metabolic profiles in normolipidic diet—but not high-fat diet-fed mice. J Nutr Biochem 2015; 26:893-902. [DOI: 10.1016/j.jnutbio.2015.03.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 02/12/2015] [Accepted: 03/02/2015] [Indexed: 01/04/2023]
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16
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Grant RW, Stephens JM. Fat in flames: influence of cytokines and pattern recognition receptors on adipocyte lipolysis. Am J Physiol Endocrinol Metab 2015; 309:E205-13. [PMID: 26058863 DOI: 10.1152/ajpendo.00053.2015] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 06/03/2015] [Indexed: 12/26/2022]
Abstract
Adipose tissue has the largest capacity to store energy in the body and provides energy through the release of free fatty acids during times of energy need. Different types of immune cells are recruited to adipose tissue under various physiological conditions, indicating that these cells contribute to the regulation of adipose tissue. One major pathway influenced by a number of immune cells is the release of free fatty acids through lipolysis during both physiological (e.g., cold stress) and pathophysiological processes (e.g., obesity, type 2 diabetes). Adipose tissue expansion during obesity leads to immune cell infiltration and adipose tissue remodeling, a homeostatic process that promotes inflammation in adipose tissue. The release of proinflammatory cytokines stimulates lipolysis and causes insulin resistance, leading to adipose tissue dysfunction and systemic disruptions of metabolism. This review focuses on the interactions of cytokines and other inflammatory molecules that regulate adipose tissue lipolysis during physiological and pathophysiological states.
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Affiliation(s)
- Ryan W Grant
- Department of Nutrition Science, Purdue University, West Lafayette, Indiana
| | - Jacqueline M Stephens
- Adipocyte Biology Lab, Pennington Biomedical Research Center, Baton Rouge, Louisiana; and Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana
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17
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Turner PA, Tang Y, Weiss SJ, Janorkar AV. Three-dimensional spheroid cell model of in vitro adipocyte inflammation. Tissue Eng Part A 2015; 21:1837-47. [PMID: 25781458 DOI: 10.1089/ten.tea.2014.0531] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
To improve treatment of obesity, a contributing factor to multiple systemic and metabolic diseases, a better understanding of metabolic state and environmental stress at the cellular level is essential. This work presents development of a three-dimensional (3D) in vitro model of adipose tissue displaying induced lipid accumulation as a function of fatty acid supplementation that, subsequently, investigates cellular responses to a pro-inflammatory stimulus, thereby recapitulating key stages of obesity progression. Three-dimensional spheroid organization of adipose cells was induced by culturing 3T3-L1 mouse preadipocytes on an elastin-like polypeptide-polyethyleneimine (ELP-PEI)-coated surface. Results indicate a more differentiated phenotype in 3D spheroid cultures relative to two-dimensional (2D) monolayer analogues based on triglyceride accumulation, CD36 and CD40 protein expression, and peroxisome proliferator-activated receptor-γ (PPAR-γ) and adiponectin mRNA expression. The 3T3-L1 adipocyte spheroid model was then used to test the effects of a pro-inflammatory microenvironment, namely maturation in the presence of elevated fatty acid levels followed by acute exposure to tumor necrosis factor alpha (TNF-α). Under these conditions, we demonstrate that metabolic function was reduced across all cultures exposed to TNF-α, especially so when pre-exposed to linoleic acid. Further, in response to TNF-α, enhanced lipolysis, monitored as increased extracellular glycerol and fatty acids levels, was observed in adipocytes cultured in the presence of exogenous fatty acids. Taken together, our 3D spheroid model showed enhanced adipogenic differentiation and presents a platform for elucidating the key phenotypic responses that occur in pro-inflammatory microenvironments that characterize obesogenic states.
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Affiliation(s)
- Paul A Turner
- 1Department of Biomedical Materials Science, School of Dentistry, University of Mississippi Medical Center, Jackson, Mississippi
| | - Yi Tang
- 2Life Sciences Institute, University of Michigan, Ann Arbor, Michigan
| | - Stephen J Weiss
- 2Life Sciences Institute, University of Michigan, Ann Arbor, Michigan
| | - Amol V Janorkar
- 1Department of Biomedical Materials Science, School of Dentistry, University of Mississippi Medical Center, Jackson, Mississippi
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18
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López-Yoldi M, Fernández-Galilea M, Laiglesia LM, Larequi E, Prieto J, Martínez JA, Bustos M, Moreno-Aliaga MJ. Cardiotrophin-1 stimulates lipolysis through the regulation of main adipose tissue lipases. J Lipid Res 2014; 55:2634-43. [PMID: 25351614 DOI: 10.1194/jlr.m055335] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cardiotrophin-1 (CT-1) is a cytokine with antiobesity properties and with a role in lipid metabolism regulation and adipose tissue function. The aim of this study was to analyze the molecular mechanisms involved in the lipolytic actions of CT-1 in adipocytes. Recombinant CT-1 (rCT-1) effects on the main proteins and signaling pathways involved in the regulation of lipolysis were evaluated in 3T3-L1 adipocytes and in mice. rCT-1 treatment stimulated basal glycerol release in a concentration- and time-dependent manner in 3T3-L1 adipocytes. rCT-1 (20 ng/ml for 24 h) raised cAMP levels, and in parallel increased protein kinase (PK)A-mediated phosphorylation of perilipin and hormone sensitive lipase (HSL) at Ser660. siRNA knock-down of HSL or PKA, as well as pretreatment with the PKA inhibitor H89, blunted the CT-1-induced lipolysis, suggesting that the lipolytic action of CT-1 in adipocytes is mainly mediated by activation of HSL through the PKA pathway. In ob/ob mice, acute rCT-1 treatment also promoted PKA-mediated phosphorylation of perilipin and HSL at Ser660 and Ser563, and increased adipose triglyceride lipase (desnutrin) content in adipose tissue. These results showed that the ability of CT-1 to regulate the activity of the main lipases underlies the lipolytic action of this cytokine in vitro and in vivo, and could contribute to CT-1 antiobesity effects.
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Affiliation(s)
- Miguel López-Yoldi
- Departments of Nutrition, Food Science, and Physiology University of Navarra, Pamplona, Navarra, Spain Centre for Nutrition Research, University of Navarra, Pamplona, Navarra, Spain
| | - Marta Fernández-Galilea
- Departments of Nutrition, Food Science, and Physiology University of Navarra, Pamplona, Navarra, Spain
| | - Laura M Laiglesia
- Departments of Nutrition, Food Science, and Physiology University of Navarra, Pamplona, Navarra, Spain Centre for Nutrition Research, University of Navarra, Pamplona, Navarra, Spain
| | - Eduardo Larequi
- Gene Therapy and Hepatology, CIMA, University of Navarra, Pamplona, Navarra, Spain
| | - Jesús Prieto
- Gene Therapy and Hepatology, CIMA, University of Navarra, Pamplona, Navarra, Spain CIBERehd Institute of Health Carlos III, Madrid, Spain
| | - J Alfredo Martínez
- Departments of Nutrition, Food Science, and Physiology University of Navarra, Pamplona, Navarra, Spain Centre for Nutrition Research, University of Navarra, Pamplona, Navarra, Spain CIBERobn, Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain
| | - Matilde Bustos
- Gene Therapy and Hepatology, CIMA, University of Navarra, Pamplona, Navarra, Spain
| | - Maria J Moreno-Aliaga
- Departments of Nutrition, Food Science, and Physiology University of Navarra, Pamplona, Navarra, Spain Centre for Nutrition Research, University of Navarra, Pamplona, Navarra, Spain CIBERobn, Physiopathology of Obesity and Nutrition, Institute of Health Carlos III, Madrid, Spain
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19
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Rumberger JM, Arch JRS, Green A. Butyrate and other short-chain fatty acids increase the rate of lipolysis in 3T3-L1 adipocytes. PeerJ 2014; 2:e611. [PMID: 25320679 PMCID: PMC4193401 DOI: 10.7717/peerj.611] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 09/16/2014] [Indexed: 12/15/2022] Open
Abstract
We determined the effect of butyrate and other short-chain fatty acids (SCFA) on rates of lipolysis in 3T3-L1 adipocytes. Prolonged treatment with butyrate (5 mM) increased the rate of lipolysis approximately 2–3-fold. Aminobutyric acid and acetate had little or no effect on lipolysis, however propionate stimulated lipolysis, suggesting that butyrate and propionate act through their shared activity as histone deacetylase (HDAC) inhibitors. Consistent with this, the HDAC inhibitor trichostatin A (1 µM) also stimulated lipolysis to a similar extent as did butyrate. Western blot data suggested that neither mitogen-activated protein kinase (MAPK) activation nor perilipin down-regulation are necessary for SCFA-induced lipolysis. Stimulation of lipolysis with butyrate and trichostatin A was glucose-dependent. Changes in AMP-activated protein kinase (AMPK) phosphorylation mediated by glucose were independent of changes in rates of lipolysis. The glycolytic inhibitor iodoacetate prevented both butyrate- and tumor necrosis factor-alpha-(TNF-α) mediated increases in rates of lipolysis indicating glucose metabolism is required. However, unlike TNF-α– , butyrate-stimulated lipolysis was not associated with increased lactate release or inhibited by activation of pyruvate dehydrogenase (PDH) with dichloroacetate. These data demonstrate an important relationship between lipolytic activity and reported HDAC inhibitory activity of butyrate, other short-chain fatty acids and trichostatin A. Given that HDAC inhibitors are presently being evaluated for the treatment of diabetes and other disorders, more work will be essential to determine if these effects on lipolysis are due to inhibition of HDAC.
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Affiliation(s)
- John M Rumberger
- Bassett Healthcare , Cooperstown, NY , USA ; Clore Laboratory, University of Buckingham , Buckingham , UK
| | | | - Allan Green
- Department of Chemistry and Biochemistry, SUNY Oneonta , Oneonta, NY , USA
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20
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Liu P, Li C, Huang J, Ji H. Regulation of adipocytes lipolysis by n-3 HUFA in grass carp (Ctenopharyngodon idellus) in vitro and in vivo. FISH PHYSIOLOGY AND BIOCHEMISTRY 2014; 40:1447-1460. [PMID: 24737494 DOI: 10.1007/s10695-014-9939-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 04/07/2014] [Indexed: 06/03/2023]
Abstract
N-3 highly unsaturated fatty acids (n-3 HUFA) have been shown to inhibit body fat accumulation in animals. To clarify the mechanism of this fat-lowering effect of n-3 HUFA in grass carp (Ctenopharyngodon idellus), two experiments were conducted. In experiment 1, isolated grass carp mature adipocytes were incubated with docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) at different concentrations for 6 h. The release of glycerol to the medium was detected, and the expression of the lipolysis-related genes was analyzed. In experiment 2, a 95-day feeding trial was conducted with two diets formulated with either lard oil (as control) or fish oil (supplying n-3 HUFA as treatment) as the main lipid source. The glycerol and free fatty acid (FFA) released from the isolated adipocytes of both groups were detected after the feeding period. The expression of select lipolysis-related genes in adipose tissue was also analyzed. The results from experiment 1 showed that the release of glycerol was significantly increased by DHA and EPA (P < 0.05). Moreover, the expression of lipolysis-related genes, such as adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), tumor necrosis factor α (TNFα) and leptin, was also significantly elevated in the treatment group (P < 0.05). Experiment 2 demonstrated that glycerol and FFA release from the isolated adipocytes were significantly higher in the treatment group compared to the control group (P < 0.05). The expression level of ATGL, HSL, TNFα and leptin in the treatment group was significantly higher than in the control group (P < 0.05). The present results provide novel evidence that n-3 HUFAs could regulate grass carp adipocyte lipolysis in vitro or in vivo, and the effect might be in part associated with their influence on the expression of lipolysis-related genes and lipolysis-related adipokines genes.
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Affiliation(s)
- Pin Liu
- College of Animal Science and Technology, Northwest A&F University, Yangling, 712100, China
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21
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Nielsen TS, Jessen N, Jørgensen JOL, Møller N, Lund S. Dissecting adipose tissue lipolysis: molecular regulation and implications for metabolic disease. J Mol Endocrinol 2014; 52:R199-222. [PMID: 24577718 DOI: 10.1530/jme-13-0277] [Citation(s) in RCA: 263] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Lipolysis is the process by which triglycerides (TGs) are hydrolyzed to free fatty acids (FFAs) and glycerol. In adipocytes, this is achieved by sequential action of adipose TG lipase (ATGL), hormone-sensitive lipase (HSL), and monoglyceride lipase. The activity in the lipolytic pathway is tightly regulated by hormonal and nutritional factors. Under conditions of negative energy balance such as fasting and exercise, stimulation of lipolysis results in a profound increase in FFA release from adipose tissue (AT). This response is crucial in order to provide the organism with a sufficient supply of substrate for oxidative metabolism. However, failure to efficiently suppress lipolysis when FFA demands are low can have serious metabolic consequences and is believed to be a key mechanism in the development of type 2 diabetes in obesity. As the discovery of ATGL in 2004, substantial progress has been made in the delineation of the remarkable complexity of the regulatory network controlling adipocyte lipolysis. Notably, regulatory mechanisms have been identified on multiple levels of the lipolytic pathway, including gene transcription and translation, post-translational modifications, intracellular localization, protein-protein interactions, and protein stability/degradation. Here, we provide an overview of the recent advances in the field of AT lipolysis with particular focus on the molecular regulation of the two main lipases, ATGL and HSL, and the intracellular and extracellular signals affecting their activity.
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Affiliation(s)
- Thomas Svava Nielsen
- The Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, DenmarkThe Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, Denmark
| | - Niels Jessen
- The Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, DenmarkThe Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, Denmark
| | - Jens Otto L Jørgensen
- The Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, Denmark
| | - Niels Møller
- The Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, Denmark
| | - Sten Lund
- The Novo Nordisk Foundation Center for Basic Metabolic ResearchSection on Integrative Physiology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3b, 6.6.30, DK-2200 N Copenhagen, DenmarkDepartment of Endocrinology and Internal MedicineAarhus University Hospital, Nørrebrogade 44, Bldg. 3.0, 8000 Aarhus C, DenmarkDepartment of Molecular MedicineAarhus University Hospital, Brendstrupgårdsvej 100, 8200 Aarhus N, Denmark
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22
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Proença ARG, Sertié RAL, Oliveira AC, Campaña AB, Caminhotto RO, Chimin P, Lima FB. New concepts in white adipose tissue physiology. ACTA ACUST UNITED AC 2014. [PMID: 24676492 PMCID: PMC3982940 DOI: 10.1590/1414-431x20132911] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Numerous studies address the physiology of adipose tissue (AT). The interest surrounding the physiology of AT is primarily the result of the epidemic outburst of obesity in various contemporary societies. Briefly, the two primary metabolic activities of white AT include lipogenesis and lipolysis. Throughout the last two decades, a new model of AT physiology has emerged. Although AT was considered to be primarily an abundant energy source, it is currently considered to be a prolific producer of biologically active substances, and, consequently, is now recognized as an endocrine organ. In addition to leptin, other biologically active substances secreted by AT, generally classified as cytokines, include adiponectin, interleukin-6, tumor necrosis factor-alpha, resistin, vaspin, visfatin, and many others now collectively referred to as adipokines. The secretion of such biologically active substances by AT indicates its importance as a metabolic regulator. Cell turnover of AT has also recently been investigated in terms of its biological role in adipogenesis. Consequently, the objective of this review is to provide a comprehensive critical review of the current literature concerning the metabolic (lipolysis, lipogenesis) and endocrine actions of AT.
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Affiliation(s)
- A R G Proença
- Laboratorio de Biotecnologia, Faculdade de Ciencias Aplicadas, Universidade Estadual de Campinas, Limeira, SP, Brasil
| | - R A L Sertié
- Departamento de Fisiologia e Biofisica, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, SP, Brasil
| | - A C Oliveira
- Instituto Superior de Ciencias Biomedicas, Universidade Estadual do Ceara, Fortaleza, CE, Brasil
| | - A B Campaña
- Departamento de Fisiologia e Biofisica, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, SP, Brasil
| | - R O Caminhotto
- Departamento de Fisiologia e Biofisica, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, SP, Brasil
| | - P Chimin
- Departamento de Fisiologia e Biofisica, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, SP, Brasil
| | - F B Lima
- Departamento de Fisiologia e Biofisica, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo, Sao Paulo, SP, Brasil
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MicroRNAs regulate human adipocyte lipolysis: effects of miR-145 are linked to TNF-α. PLoS One 2014; 9:e86800. [PMID: 24475180 PMCID: PMC3901697 DOI: 10.1371/journal.pone.0086800] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 12/13/2013] [Indexed: 11/24/2022] Open
Abstract
MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression and have multiple effects in various tissues including adipose inflammation, a condition characterized by increased local release of the pro-lipolytic cytokine tumor necrosis factor-alpha (TNF-α). Whether miRNAs regulate adipocyte lipolysis is unknown. We set out to determine whether miRNAs affect adipocyte lipolysis in human fat cells. To this end, eleven miRNAs known to be present in human adipose tissue were over-expressed in human in vitro differentiated adipocytes followed by assessments of TNF-α and glycerol levels in conditioned media after 48 h. Three miRNAs (miR-145, -26a and let-7d) modulated both parameters in parallel. However, while miR-26a and let-7d decreased, miR-145 increased both glycerol release and TNF-α secretion. Further studies were focused therefore on miR-145 since this was the only stimulator of lipolysis and TNF-α secretion. Time-course analysis demonstrated that miR-145 over-expression up-regulated TNF-α expression/secretion followed by increased glycerol release. Increase in TNF-α production by miR-145 was mediated via activation of p65, a member of the NF-κB complex. In addition, miR-145 down-regulated the expression of the protease ADAM17, resulting in an increased fraction of membrane bound TNF-α, which is the more biologically active form of TNF-α. MiR-145 overexpression also increased the phosphorylation of activating serine residues in hormone sensitive lipase and decreased the mRNA expression of phosphodiesterase 3B, effects which are also observed upon TNF-α treatment in human adipocytes. We conclude that miR-145 regulates adipocyte lipolysis via multiple mechanisms involving increased production and processing of TNF-α in fat cells.
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Lee MJ, Fried SK. Glucocorticoids antagonize tumor necrosis factor-α-stimulated lipolysis and resistance to the antilipolytic effect of insulin in human adipocytes. Am J Physiol Endocrinol Metab 2012; 303:E1126-33. [PMID: 22949029 PMCID: PMC3492859 DOI: 10.1152/ajpendo.00228.2012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
High concentrations of TNF within obese adipose tissue increase basal lipolysis and antagonize insulin signaling. Adipocytes of the obese are also exposed to elevated levels of glucocorticoids (GCs), which antagonize TNF actions in many cell types. We tested the hypothesis that TNF decreases sensitivity to the antilipolytic effect of insulin and that GCs antagonize this effect in differentiated human adipocytes. Lipolysis and expression levels of lipolytic proteins were measured after treating adipocytes with TNF, dexamethasone (DEX), or DEX + TNF for up to 48 h. TNF not only increased basal lipolysis, it caused resistance to the antilipolytic effects of insulin in human adipocytes. DEX alone did not significantly affect lipolysis. Cotreatment with DEX blocked TNF induction of basal lipolysis and insulin resistance by antagonizing TNF stimulation of PKA-mediated phosphorylation of hormone-sensitive lipase (HSL) at Ser⁵⁶³ and Ser⁶⁶⁰ and perilipin. TNF did not affect perilipin, HSL, or phosphodiesterase-3B mass but paradoxically suppressed adipose tissue triglyceride lipase expression, and this effect was blocked by DEX. The extent to which GCs can restrain the lipolytic actions of TNF may both diminish the potentially deleterious effects of excess lipolysis and contribute to fat accumulation in obesity.
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Affiliation(s)
- Mi-Jeong Lee
- Section of Endocrinology, Diabetes, and Nutrition, Department of Medicine, Boston University, Boston, Massachusetts, USA.
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25
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Wang X, Huang M, Wang Y. The effect of insulin, TNFα and DHA on the proliferation, differentiation and lipolysis of preadipocytes isolated from large yellow croaker (Pseudosciaena Crocea R.). PLoS One 2012; 7:e48069. [PMID: 23110176 PMCID: PMC3482209 DOI: 10.1371/journal.pone.0048069] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2012] [Accepted: 09/20/2012] [Indexed: 01/19/2023] Open
Abstract
Fish final product can be affected by excessive lipid accumulation. Therefore, it is important to develop strategies to control obesity in cultivated fish to strengthen the sustainability of the aquaculture industry. As in mammals, the development of adiposity in fish depends on hormonal, cytokine and dietary factors. In this study, we investigated the proliferation and differentiation of preadipocytes isolated from the large yellow croaker and examined the effects of critical factors such as insulin, TNFα and DHA on the proliferation, differentiation and lipolysis of adipocytes. Preadipocytes were isolated by collagenase digestion, after which their proliferation was evaluated. The differentiation process was optimized by assaying glycerol-3-phosphate dehydrogenase (GPDH) activity. Oil red O staining and electron microscopy were performed to visualize the accumulated triacylglycerol. Gene transcript levels were measured using SYBR green quantitative real-time PCR. Insulin promoted preadipocytes proliferation, stimulated cell differentiation and decreased lipolysis of mature adipocytes. TNFα and DHA inhibited cell proliferation and differentiation. While TNFα stimulated mature adipocyte lipolysis, DHA showed no lipolytic effect on adipocytes. The expressions of adipose triglyceride lipase (ATGL), fatty acid synthase (FAS), lipoprotein lipase (LPL) and peroxisome proliferator-activated receptor α, γ (PPARα, PPARγ) were quantified during preadipocytes differentiation and adipocytes lipolysis to partly explain the regulation mechanisms. In summary, the results of this study indicated that although preadipocytes proliferation and the differentiation process in large yellow croaker are similar to these processes in mammals, the effects of critical factors such as insulin, TNFα and DHA on fish adipocytes development are not exactly the same. Our findings fill in the gaps in the basic data regarding the effects of critical factors on adiposity development in fish and will facilitate the further study of molecular mechanism by which these factors act in fish and the application of this knowledge to eventually control obesity in cultured species.
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Affiliation(s)
- Xinxia Wang
- Institute of Feed Science, Zhejiang University, Hangzhou, Zhejiang Province, People’s Republic of China
| | - Ming Huang
- Institute of Feed Science, Zhejiang University, Hangzhou, Zhejiang Province, People’s Republic of China
| | - Yizhen Wang
- Institute of Feed Science, Zhejiang University, Hangzhou, Zhejiang Province, People’s Republic of China
- * E-mail:
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26
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Dave S, Kaur NJ, Nanduri R, Dkhar HK, Kumar A, Gupta P. Inhibition of adipogenesis and induction of apoptosis and lipolysis by stem bromelain in 3T3-L1 adipocytes. PLoS One 2012; 7:e30831. [PMID: 22292054 PMCID: PMC3265525 DOI: 10.1371/journal.pone.0030831] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 12/27/2011] [Indexed: 02/07/2023] Open
Abstract
The phytotherapeutic protein stem bromelain (SBM) is used as an anti-obesity alternative medicine. We show at the cellular level that SBM irreversibly inhibits 3T3-L1 adipocyte differentiation by reducing adipogenic gene expression and induces apoptosis and lipolysis in mature adipocytes. At the molecular level, SBM suppressed adipogenesis by downregulating C/EBPα and PPARγ independent of C/EBPβ gene expression. Moreover, mRNA levels of adipocyte fatty acid-binding protein (ap2), fatty acid synthase (FAS), lipoprotein lipase (LPL), CD36, and acetyl-CoA carboxylase (ACC) were also downregulated by SBM. Additionally, SBM reduced adiponectin expression and secretion. SBM's ability to repress PPARγ expression seems to stem from its ability to inhibit Akt and augment the TNFα pathway. The Akt–TSC2–mTORC1 pathway has recently been described for PPARγ expression in adipocytes. In our experiments, TNFα upregulation compromised cell viability of mature adipocytes (via apoptosis) and induced lipolysis. Lipolytic response was evident by downregulation of anti-lipolytic genes perilipin, phosphodiestersae-3B (PDE3B), and GTP binding protein Giα1, as well as sustained expression of hormone sensitive lipase (HSL). These data indicate that SBM, together with all-trans retinoic-acid (atRA), may be a potent modulator of obesity by repressing the PPARγ-regulated adipogenesis pathway at all stages and by augmenting TNFα-induced lipolysis and apoptosis in mature adipocytes.
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Affiliation(s)
- Sandeep Dave
- Institute of Microbial Technology (CSIR), Chandigarh, India
| | - Naval Jit Kaur
- Institute of Microbial Technology (CSIR), Chandigarh, India
| | | | | | - Ashwani Kumar
- Institute of Microbial Technology (CSIR), Chandigarh, India
| | - Pawan Gupta
- Institute of Microbial Technology (CSIR), Chandigarh, India
- * E-mail:
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27
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Yang X, Zhang X, Heckmann BL, Lu X, Liu J. Relative contribution of adipose triglyceride lipase and hormone-sensitive lipase to tumor necrosis factor-α (TNF-α)-induced lipolysis in adipocytes. J Biol Chem 2011; 286:40477-85. [PMID: 21969372 DOI: 10.1074/jbc.m111.257923] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
TNF-α potently stimulates basal lipolysis in adipocytes, which may contribute to hyperlipidemia and peripheral insulin resistance in obesity. Recent studies show that adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) act sequentially in catalyzing the first two steps of adipose lipolysis in response to β-adrenergic stimulation. Here, we sought to determine their functional roles in TNF-α-induced lipolysis. Silencing of ATGL expression in adipocytes almost completely abolished basal and TNF-α-induced glycerol release. In comparison, the glycerol release under the same conditions was only partially decreased upon reduction in expression of either HSL or the ATGL coactivator CGI-58. Interestingly, overexpression of ATGL restored the lipolytic rates in cells with silenced HSL or CGI-58, indicating a predominant role for ATGL. While expression of ATGL, HSL and CGI-58 remains mostly unaffected, TNF-α treatment caused a rapid abrogation of the ATGL inhibitory protein G0S2. TNF-α drastically decreased the level of G0S2 mRNA, and the level of G0S2 protein could be maintained by inhibiting proteasomal protein degradation using MG-132. Furthermore, coexpression of G0S2 was able to significantly decrease TNF-α-stimulated lipolysis mediated by overexpressed ATGL or CGI-58. We propose that the early reduction in G0S2 content is permissive for TNF-α-induced lipolysis.
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Affiliation(s)
- Xingyuan Yang
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Scottsdale, Arizona 85259, USA
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28
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Pinent M, Prokesch A, Hackl H, Voshol PJ, Klatzer A, Walenta E, Panzenboeck U, Kenner L, Trajanoski Z, Hoefler G, Bogner-Strauss JG. Adipose triglyceride lipase and hormone-sensitive lipase are involved in fat loss in JunB-deficient mice. Endocrinology 2011; 152:2678-89. [PMID: 21540289 PMCID: PMC3152802 DOI: 10.1210/en.2010-1477] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Proteins of the activator protein-1 family are known to have roles in many physiological processes such as proliferation, apoptosis, and inflammation. However, their role in fat metabolism has yet to be defined in more detail. Here we study the impact of JunB deficiency on the metabolic state of mice. JunB knockout (JunB-KO) mice show markedly decreased weight gain, reduced fat mass, and a low survival rate compared with control mice. If fed a high-fat diet, the weight gain of JunB-KO mice is comparable to control mice and the survival rate improves dramatically. Along with normal expression of adipogenic marker genes in white adipose tissue (WAT) of JunB-KO mice, this suggests that adipogenesis per se is not affected by JunB deficiency. This is supported by in vitro data, because neither JunB-silenced 3T3-L1 cells nor mouse embryonic fibroblasts from JunB-KO mice show a change in adipogenic potential. Interestingly, the key enzymes of lipolysis, adipose triglyceride lipase and hormone-sensitive lipase, were significantly increased in WAT of fasted JunB-KO mice. Concomitantly, the ratio of plasma free fatty acids per gram fat mass was increased, suggesting an elevated lipolytic rate under fasting conditions. Furthermore, up-regulation of TNFα and reduced expression of perilipin indicate that this pathway is also involved in increased lipolytic rate in these mice. Additionally, JunB-KO mice are more insulin sensitive than controls and show up-regulation of lipogenic genes in skeletal muscle, indicating a shuttling of energy substrates from WAT to skeletal muscle. In summary, this study provides valuable insights into the impact of JunB deficiency on the metabolic state of mice.
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Affiliation(s)
- Montserrat Pinent
- Institute for Genomics and Bioinformatics, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
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29
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Abstract
HIV-1/highly active antiretroviral therapy-associated lipodystrophy syndrome (HALS) is an adipose tissue redistribution disorder characterized by subcutaneous adipose tissue lipoatrophy, sometimes including visceral adipose tissue hypertrophy and accumulation of dorsocervical fat ('buffalo hump'). The pathophysiology of HALS appears to be multifactorial and several key pathophysiological factors associated with HALS have been identified. These include mitochondrial dysfunction, adipocyte differentiation disturbances, high adipocyte lipolysis, and adipocyte apoptosis. These alterations in adipose tissue biology expand to involve systemic metabolism through alterations in endocrine functions of adipose tissue (via disturbed adipokine release), enhanced production of pro-inflammatory cytokines and excessive free fatty-acid release due to lipolysis. The deleterious action of some antiretroviral drugs is an important factor in eliciting these alterations in adipose tissue. However, HIV-1 infection-related events and HIV-1-encoded proteins also contribute directly to the complex development of HALS through effects on adipocyte biology, or indirectly through the promotion of local inflammation in adipose tissue.
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Affiliation(s)
- Marta Giralt
- Department of Biochemistry and Molecular Biology and Institut de Biomedicina (IBUB), University of Barcelona, Barcelona, Catalonia, Spain.
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30
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Abstract
HIV-associated lipodystrophy is clinically characterized by body fat changes including subcutaneous fat loss (lipoatrophy) with or without truncal fat accumulation (lipohypertrophy). Thymidine nucleoside reverse transcriptase inhibitors, stavudine and to a lesser extent zidovudine, are major contributors for lipoatrophy. Drug factors are not clear for lipohypertrophy. Restoration to health with effective viral suppression and weight gain may be factors playing significant roles in lipohypertrophy. Mitochondrial dysfunction and inflammation in subcutaneous adipose tissue are key factors in the pathogenesis of HIV-associated lipoatrophy. The pathogenesis of lipohypertrophy is less well understood. Switching from thymidine nucleoside reverse transcriptase inhibitors restores subcutaneous fat in patients with HIV-associated lipoatrophy, but improvement is slow and limited. Surgical filling cosmetically improves facial lipoatrophy. Exercise and diet may reduce increased visceral adipose tissue. Liposuction may be useful to remove superficial, localized fat accumuli.
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Affiliation(s)
- Esteban Martínez
- Infectious Diseases Unit, Hospital Clínic-Institut d'Investigaciones Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain.
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31
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Chaves VE, Frasson D, Kawashita NH. Several agents and pathways regulate lipolysis in adipocytes. Biochimie 2011; 93:1631-40. [PMID: 21658426 DOI: 10.1016/j.biochi.2011.05.018] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 05/23/2011] [Indexed: 01/01/2023]
Abstract
Adipose tissue is the only tissue capable of hydrolyzing its stores of triacylglycerol (TAG) and of mobilizing fatty acids and glycerol in the bloodstream so that they can be used by other tissues. The full hydrolysis of TAG depends on the activity of three enzymes, adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL) and monoacylglycerol lipase, each of which possesses a distinct regulatory mechanism. Although more is known about HSL than about the other two enzymes, it has recently been shown that HLS and ATGL can be activated simultaneously, such that the mechanism that enables HSL to access the surface of lipid droplets also permits the stimulation of ATGL. The classical pathway of lipolysis activation in adipocytes is cAMP-dependent. The production of cAMP is modulated by G-protein-coupled receptors of the Gs/Gi family and cAMP degradation is regulated by phosphodiesterase. However, other pathways that activate TAG hydrolysis are currently under investigation. Lipolysis can also be started by G-protein-coupled receptors of the Gq family, through molecular mechanisms that involve phospholipase C, calmodulin and protein kinase C. There is also evidence that increased lipolytic activity in adipocytes occurs after stimulation of the mitogen-activated protein kinase pathway or after cGMP accumulation and activation of protein kinase G. Several agents contribute to the control of lipolysis in adipocytes by modulating the activity of HSL and ATGL. In this review, we have summarized the signalling pathways activated by several agents involved in the regulation of TAG hydrolysis in adipocytes.
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Affiliation(s)
- Valéria Ernestânia Chaves
- Department of Basic Sciences in Health, Federal University of Mato Grosso, Cuiabá, Mato Grosso, Brazil
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32
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Burri L, Bjørndal B, Wergedahl H, Berge K, Bohov P, Svardal A, Berge RK. Tetradecylthioacetic acid increases hepatic mitochondrial β-oxidation and alters fatty acid composition in a mouse model of chronic inflammation. Lipids 2011; 46:679-89. [PMID: 21479675 PMCID: PMC3131506 DOI: 10.1007/s11745-011-3536-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Accepted: 01/10/2011] [Indexed: 12/23/2022]
Abstract
The administration of tetradecylthioacetic acid (TTA), a hypolipidemic and anti-inflammatory modified bioactive fatty acid, has in several experiments based on high fat diets been shown to improve lipid transport and utilization. It was suggested that increased mitochondrial and peroxisomal fatty acid oxidation in the liver of Wistar rats results in reduced plasma triacylglycerol (TAG) levels. Here we assessed the potential of TTA to prevent tumor necrosis factor (TNF) α-induced lipid modifications in human TNFα (hTNFα) transgenic mice. These mice are characterized by reduced β-oxidation and changed fatty acid composition in the liver. The effect of dietary treatment with TTA on persistent, low-grade hTNFα overexpression in mice showed a beneficial effect through decreasing TAG plasma concentrations and positively affecting saturated and monounsaturated fatty acid proportions in the liver, leading to an increased anti-inflammatory fatty acid index in this group. We also observed an increase of mitochondrial β-oxidation in the livers of TTA treated mice. Concomitantly, there were enhanced plasma levels of carnitine, acetyl carnitine, propionyl carnitine, and octanoyl carnitine, no changed levels in trimethyllysine and palmitoyl carnitine, and a decreased level of the precursor for carnitine, called γ-butyrobetaine. Nevertheless, TTA administration led to increased hepatic TAG levels that warrant further investigations to ascertain that TTA may be a promising candidate for use in the amelioration of inflammatory disorders characterized by changed lipid metabolism due to raised TNFα levels.
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Affiliation(s)
- Lena Burri
- Section of Medical Biochemistry, Institute of Medicine, Haukeland University Hospital, University of Bergen, N-5021, Bergen, Norway.
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Zúñiga LA, Shen WJ, Joyce-Shaikh B, Pyatnova EA, Richards AG, Thom C, Andrade SM, Cua DJ, Kraemer FB, Butcher EC. IL-17 regulates adipogenesis, glucose homeostasis, and obesity. THE JOURNAL OF IMMUNOLOGY 2010; 185:6947-59. [PMID: 21037091 DOI: 10.4049/jimmunol.1001269] [Citation(s) in RCA: 274] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Inflammatory mediators have the potential to impact a surprising range of diseases, including obesity and its associated metabolic syndrome. In this paper, we show that the proinflammatory cytokine IL-17 inhibits adipogenesis, moderates adipose tissue (AT) accumulation, and regulates glucose metabolism in mice. IL-17 deficiency enhances diet-induced obesity in mice and accelerates AT accumulation even in mice fed a low-fat diet. In addition to potential systemic effects, IL-17 is expressed locally in AT by leukocytes, predominantly by γδ T cells. IL-17 suppresses adipocyte differentiation from mouse-derived 3T3-L1 preadipocytes in vitro, and inhibits expression of genes encoding proadipogenic transcription factors, adipokines, and molecules involved in lipid and glucose metabolism. IL-17 also acts on differentiated adipocytes, impairing glucose uptake, and young IL-17-deficient mice show enhanced glucose tolerance and insulin sensitivity. Our findings implicate IL-17 as a negative regulator of adipogenesis and glucose metabolism in mice, and show that it delays the development of obesity.
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Affiliation(s)
- Luis A Zúñiga
- Laboratory of Immunology and Vascular Biology, Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305-5324, USA
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Thompson BR, Lobo S, Bernlohr DA. Fatty acid flux in adipocytes: the in's and out's of fat cell lipid trafficking. Mol Cell Endocrinol 2010; 318:24-33. [PMID: 19720110 PMCID: PMC2826553 DOI: 10.1016/j.mce.2009.08.015] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 08/19/2009] [Accepted: 08/20/2009] [Indexed: 12/21/2022]
Abstract
The trafficking of fatty acids into and out of adipocytes is regulated by a complex series of proteins and enzymes and is under control by a variety of hormonal and metabolic factors. The biochemical basis of fatty acid influx, despite its widespread appreciation, remains enigmatic with regard to the biophysical and biochemical properties that facilitate long-chain fatty acid uptake. Fatty acid efflux is initiated by hormonally controlled lipolysis of the droplet stores and produces fatty acids that must transit from their site of production to the plasma membrane and subsequently out of the cells. This review will focus on the "in's and out's" of fatty acid trafficking and summarize the current concepts in the field.
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Affiliation(s)
- Brian R Thompson
- Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota-Twin Cities, 321 Church St. SE, Minneapolis, MN 55455, USA
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35
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Castelar L, Silva MM, Castelli EC, Deghaide NHS, Mendes-Junior CT, Machado AA, Donadi EA, Fernandes APM. Interleukin-18 and interferon-gamma polymorphisms in Brazilian human immunodeficiency virus-1-infected patients presenting with lipodystrophy syndrome. ACTA ACUST UNITED AC 2010; 76:126-30. [PMID: 20331838 DOI: 10.1111/j.1399-0039.2010.01471.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytokines play important roles in the pathogenesis of lipodystrophy syndrome (LS). Single nucleotide polymorphisms (SNPs) at positions -607(C/A) and -137(C/G) in the promoter region of the interleukin-18 (IL-18) gene and at position +874(T/A) of the interferon-gamma (IFN-gamma) gene are related to the expression of these cytokines. To examine whether IL-18 and IFN-gamma polymorphisms are associated with LS, these SNPs were genotyped in 88 human immunodeficiency virus (HIV)-infected patients presenting LS, 79 HIV-infected without LS, and 133 healthy controls. The -607A allele, -607AA genotype, and -137G/-607A and -137C/-607A haplotypes in the IL-18 gene were over-represented in HIV patients presenting LS. The -137G/-607C haplotype was associated with protection against LS. These results indicate that the -607(C/A) SNP is associated with LS development in HIV-infected patients.
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Affiliation(s)
- L Castelar
- College of Nursing of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
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36
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Villarroya F, Domingo P, Giralt M. Drug-induced lipotoxicity: Lipodystrophy associated with HIV-1 infection and antiretroviral treatment. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1801:392-9. [DOI: 10.1016/j.bbalip.2009.09.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 09/09/2009] [Accepted: 09/17/2009] [Indexed: 12/24/2022]
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37
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Ogasawara J, Kitadate K, Nishioka H, Fujii H, Sakurai T, Kizaki T, Izawa T, Ishida H, Ohno H. Oligonol, a new lychee fruit-derived low-molecular form of polyphenol, enhances lipolysis in primary rat adipocytes through activation of the ERK1/2 pathway. Phytother Res 2010; 23:1626-33. [PMID: 19548254 DOI: 10.1002/ptr.2846] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The effect of Oligonol, a phenolic product from lychee fruit polyphenol (LFP) containing catechin-type monomers and lower oligomers of proanthocyanidin, on lipolysis in primary adipocytes was investigated in order to examine the possible mechanism underlying the regulation of in vivo metabolism in fat. Oligonol significantly increased lipolysis, which was accompanied by both activation of extracellular signaling-related kinase 1/2 (ERK1/2) and down-regulation of perilipin protein expression, without an increase in intracellular cAMP production. The increase in lipolysis with Oligonol was prevented completely by pretreatment with either PD98059 or U0126, selective ERK1/2 inhibitors, which also prevented the reduction in the expression of perilipin protein. Tumor necrosis factor-alpha also down-regulated the expression of perilipin protein. However, there was no significant alteration in the expression of Galphai protein with Oligonol. These findings indicate that Oligonol enhances lipolysis in primary adipocytes, independent of cAMP production, but its effect is dependent on activation of the ERK1/2 pathway, leading to down-regulation of perilipin protein expression.
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Affiliation(s)
- Junetsu Ogasawara
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University, School of Medicine, Mitaka, Tokyo 181-8611, Japan.
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38
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Sakurai T, Kitadate K, Nishioka H, Fujii H, Kizaki T, Kondoh Y, Izawa T, Ishida H, Radák Z, Ohno H. Oligomerized grape seed polyphenols attenuate inflammatory changes due to antioxidative properties in coculture of adipocytes and macrophages. J Nutr Biochem 2010; 21:47-54. [DOI: 10.1016/j.jnutbio.2008.10.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2008] [Revised: 09/29/2008] [Accepted: 10/02/2008] [Indexed: 11/28/2022]
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39
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Chen X, Xun K, Chen L, Wang Y. TNF-alpha, a potent lipid metabolism regulator. Cell Biochem Funct 2009; 27:407-16. [PMID: 19757404 DOI: 10.1002/cbf.1596] [Citation(s) in RCA: 156] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
As a multifunctional cytokine, tumor necrosis factor alpha (TNF-alpha) exerts a series of biological actions in different cells, tissues, organs, and species and has been demonstrated to regulate and interfere with energy metabolism, especially lipid homeostasis. A large body of researches suggested that the effects of TNF-alpha on lipid metabolism mainly include five aspects: (1) suppresses free fatty acid (FFA) uptake and promotes lipogenesis; (2) induces lipolysis; (3) inhibits lipid-metabolism-related enzymes activity; (4) regulates cholesterol metabolism; (5) regulates other adipocyte-derived adipokines. The molecular mechanisms underlying these actions are complex and several signal transduction pathways might be involved. Regulation of metabolism-related gene expression at transcriptional and protein levels and impact on enzymes activity might be of importance. Identification and verification of these pathways might provide novel potential strategies and drug targets for dyslipidemia therapy. However, the inconsistent and even conflict conclusions on lipid profile drawn from human subjects after infliximab therapy poses the possibility that the effect of TNF-alpha on lipid metabolism might be more complicated than it appeared to be.
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Affiliation(s)
- Xiuping Chen
- Fujian College of Traditional Chinese Medicine, Fuzhou, China.
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Lien CC, Au LC, Tsai YL, Ho LT, Juan CC. Short-term regulation of tumor necrosis factor-alpha-induced lipolysis in 3T3-L1 adipocytes is mediated through the inducible nitric oxide synthase/nitric oxide-dependent pathway. Endocrinology 2009; 150:4892-900. [PMID: 19819972 DOI: 10.1210/en.2009-0403] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
TNF-alpha has several effects on adipocytes that may be related to the development of type 2 diabetes in obese subjects. Many studies demonstrated that long-term treatment with TNF-alpha increases lipolysis in adipocytes. However, the short-term (<4 h) effects of TNF-alpha on lipolysis have not been well investigated. The aim of this study was to investigate the short-term regulatory mechanism of TNF-alpha-induced lipolysis in 3T3-L1 adipocytes. Well-differentiated 3T3-L1 adipocytes were used. Lipolysis was determined by measuring glycerol release. Expression of inducible nitric oxide (iNOS) and nitric oxide (NO) production were measured, respectively, by Western blots and the Griess reagent. A selective iNOS inhibitor (s-ethylisothiourea . HBr), an adenylyl cyclase inhibitor (SQ22536), and a guanylyl cyclase inhibitor (LY83583) were used to investigate the involvement of iNOS, cAMP, and cGMP in TNF-alpha-induced lipolysis. Transient transfection with iNOS short hairpin RNA was performed to confirm the involvement of iNOS in TNF-alpha-induced lipolysis. Phosphorylation of hormone-sensitive lipase (HSL) was measured by immunoprecipitation and Western blotting. Results showed that short-term TNF-alpha treatment significantly increased lipolysis, iNOS expression, and NO production in a time- and dose-dependent manner. Furthermore, treatment with the NO donor S-nitroso-N-acetylpenicillamine also stimulated lipolysis and HSL phosphorylation in 3T3-L1 adipocytes. Moreover, pretreatment with inhibitors of iNOS and guanylate cyclase, but not an adenylate cyclase inhibitor, abolished TNF-alpha-induced lipolysis and HSL phosphorylation. Suppression of TNF-alpha-induced iNOS expression using short hairpin RNA significantly reduced TNF-alpha-induced lipolysis. In conclusion, short-term TNF-alpha treatment induces lipolysis in 3T3-L1 adipocytes by increasing iNOS expression and NO production, which activates the guanylyl cyclase/cGMP-dependent pathway and induces phosphorylation of HSL.
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Affiliation(s)
- Chih-Chan Lien
- Department of Physiology, National Yang-Ming University, Number 155, Section 2, Li-Nong Street, Taipei, Taiwan.
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Abstract
Human obesity and its complications are an increasing burden in developed and underdeveloped countries. Adipose tissue mass and the mechanisms that control it are central to elucidating the aetiology of obesity and insulin resistance. Over the past 15 years tremendous progress has been made in several avenues relating to adipose tissue. Knowledge of the lipolytic machinery has grown with the identification of new lipases, cofactors and interactions between proteins and lipids that are central to the regulation of basal and stimulated lipolysis. The dated idea of an inert lipid droplet has been appropriately revamped to that of a dynamic and highly-structured organelle that in itself offers regulatory control over lipolysis. The present review provides an overview of the numerous partners and pathways involved in adipose tissue lipolysis and their interaction under various metabolic states. Integration of these findings into whole adipose tissue metabolism and its systemic effects is also presented in the context of inflammation and insulin resistance.
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Lipolysis and lipid mobilization in human adipose tissue. Prog Lipid Res 2009; 48:275-97. [PMID: 19464318 DOI: 10.1016/j.plipres.2009.05.001] [Citation(s) in RCA: 518] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Revised: 05/04/2009] [Accepted: 05/08/2009] [Indexed: 01/04/2023]
Abstract
Triacylglycerol (TAG) stored in adipose tissue (AT) can be rapidly mobilized by the hydrolytic action of the three main lipases of the adipocyte. The non-esterified fatty acids (NEFA) released are used by other tissues during times of energy deprivation. Until recently hormone-sensitive lipase (HSL) was considered to be the key rate-limiting enzyme responsible for regulating TAG mobilization. A novel lipase named adipose triglyceride lipase/desnutrin (ATGL) has been identified as playing an important role in the control of fat cell lipolysis. Additionally perilipin and other proteins of the surface of the lipid droplets protecting or exposing the TAG core of the droplets to lipases are also potent regulators of lipolysis. Considerable progress has been made in understanding the mechanisms of activation of the various lipases. Lipolysis is under tight hormonal regulation. The best understood hormonal effects on AT lipolysis concern the opposing regulation by insulin and catecholamines. Heart-derived natriuretic peptides (i.e., stored in granules in the atrial and ventricle cardiomyocytes and exerting stimulating effects on diuresis and natriuresis) and numerous autocrine/paracrine factors originating from adipocytes and other cells of the stroma-vascular fraction may also participate in the regulation of lipolysis. Endocrine and autocrine/paracrine factors cooperate and lead to a fine regulation of lipolysis in adipocytes. Age, anatomical site, sex, genotype and species differences all play a part in the regulation of lipolysis. The manipulation of lipolysis has therapeutic potential in the metabolic disorders frequently associated with obesity and probably in several inborn errors of metabolism.
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Blumer JB, Lord K, Saunders TL, Pacchioni A, Black C, Lazartigues E, Varner KJ, Gettys TW, Lanier SM. Activator of G protein signaling 3 null mice: I. Unexpected alterations in metabolic and cardiovascular function. Endocrinology 2008; 149:3842-9. [PMID: 18450958 PMCID: PMC2488243 DOI: 10.1210/en.2008-0050] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Activator of G protein signaling (AGS)-3 plays functional roles in cell division, synaptic plasticity, addictive behavior, and neuronal development. As part of a broad effort to define the extent of functional diversity of AGS3-regulated-events in vivo, we generated AGS3 null mice. Surprisingly, AGS3 null adult mice exhibited unexpected alterations in cardiovascular and metabolic functions without any obvious changes in motor skills, basic behavioral traits, and brain morphology. AGS3 null mice exhibited a lean phenotype, reduced fat mass, and increased nocturnal energy expenditure. AGS3 null mice also exhibited altered blood pressure control mechanisms. These studies expand the functional repertoire for AGS3 and other G protein regulatory proteins providing unexpected mechanisms by which G protein systems may be targeted to influence obesity and cardiovascular function.
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Affiliation(s)
- Joe B Blumer
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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Kang K, Reilly SM, Karabacak V, Gangl MR, Fitzgerald K, Hatano B, Lee CH. Adipocyte-derived Th2 cytokines and myeloid PPARdelta regulate macrophage polarization and insulin sensitivity. Cell Metab 2008; 7:485-95. [PMID: 18522830 PMCID: PMC2586840 DOI: 10.1016/j.cmet.2008.04.002] [Citation(s) in RCA: 553] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 03/05/2008] [Accepted: 04/01/2008] [Indexed: 12/14/2022]
Abstract
The polarization of adipose tissue-resident macrophages toward the alternatively activated, anti-inflammatory M2 phenotype is believed to improve insulin sensitivity. However, the mechanisms controlling tissue macrophage activation remain unclear. Here we show that adipocytes are a source of Th2 cytokines, including IL-13 and to a lesser extent IL-4, which induce macrophage PPARdelta/beta (Ppard/b) expression through a STAT6 binding site on its promoter to activate alternative activation. Coculture studies indicate that Ppard ablation renders macrophages incapable of transition to the M2 phenotype, which in turns causes inflammation and metabolic derangement in adipocytes. Remarkably, a similar regulatory mechanism by hepatocyte-derived Th2 cytokines and macrophage PPARdelta is found to control hepatic lipid metabolism. The physiological relevance of this paracrine pathway is demonstrated in myeloid-specific PPARdelta(-/-) mice, which develop insulin resistance and show increased adipocyte lipolysis and severe hepatosteatosis. These findings provide a molecular basis to modulate tissue-resident macrophage activation and insulin sensitivity.
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Affiliation(s)
- Kihwa Kang
- Department of Genetics and Complex Diseases, Division of Biological Sciences, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
| | - Shannon M. Reilly
- Department of Genetics and Complex Diseases, Division of Biological Sciences, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
| | - Volkan Karabacak
- Department of Genetics and Complex Diseases, Division of Biological Sciences, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
| | - Matthew R. Gangl
- Department of Genetics and Complex Diseases, Division of Biological Sciences, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
| | - Kelly Fitzgerald
- Department of Genetics and Complex Diseases, Division of Biological Sciences, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
| | - Ben Hatano
- Department of Genetics and Complex Diseases, Division of Biological Sciences, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
| | - Chih-Hao Lee
- Department of Genetics and Complex Diseases, Division of Biological Sciences, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA
- *Correspondence should be addressed to C.-H. L. e-mail: Chih-Hao Lee, PhD, Department of Genetics and Complex Diseases, Harvard School of Public Health, 665 Huntington Ave, Bldg2, Rm 119, Boston, MA 02115, USA Phone: (617) 432-5778, Fax (617) 432-5236
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Moore GBT, Pickavance LC, Briscoe CP, Clapham JC, Buckingham RE, Wilding JPH. Energy restriction enhances therapeutic efficacy of the PPARgamma agonist, rosiglitazone, through regulation of visceral fat gene expression. Diabetes Obes Metab 2008; 10:251-63. [PMID: 18269641 DOI: 10.1111/j.1463-1326.2007.00697.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
AIM Consumption of a palatable diet can induce hyperphagia, leading to weight gain (dietary obesity) and insulin resistance in rats. Thiazolidinediones (TZDs) can also induce hyperphagia in rats but conversely have an insulin-sensitizing effect. The aim of this study was to investigate whether preventing TZD-induced hyperphagia (i.e. energy restriction) in dietary obese (DIO) rats would enhance the insulin-sensitizing effects of treatment at a therapeutic dose; and, within this paradigm, to produce an original survey of candidate TZD-gene targets in the clinically relevant visceral white adipose tissue (WAT) depot. METHODS DIO rats that were either freely fed or energy restricted (i.e. pair-fed to the level of untreated controls) were treated with rosiglitazone maleate (RSG; 3 mg/kg/day) for 2 weeks, the restricted group controlling for treatment-induced hyperphagia and weight gain. The outcome measures were circulating concentrations of various biochemical markers of insulin resistance, and gene expression was measured in epididymal WAT. RESULTS In both freely fed and pair-fed groups, compared to untreated DIO controls, RSG reduced plasma levels of insulin (-29% and -43%; p < 0.05 and p < 0.001, respectively), free fatty acids (FFAs; -45% and -48%; p < 0.01 and p < 0.001, respectively) and triglycerides (TGs; -63% and -72%; both p < 0.001), reflected in improved insulin sensitivity, as measured by homeostasis model assessment (-29% and -43%; p < 0.01 and p < 0.0001). RSG also increased the expression of the fatty acid transport/synthesis genes, fatty acid transport protein (2.4-3.2-fold), epidermal fatty acid-binding protein (FABP; 1.7-2.0-fold), heart FABP (25-29-fold) and fatty acid synthase (2.3-2.9-fold; all p < 0.05) in both groups. Adipocyte FABP was also increased by RSG treatment, but only in combination with energy restriction (1.52-fold; p < 0.05) as was hexokinase II expression (p < 0.001). In contrast, the drug had no effect on expression of several genes associated with lipolysis. Although obesity-induced hyperleptinaemia was normalized only in the energy-restricted group, leptin messenger RNA (mRNA) expression was reduced in both treated groups (all p < 0.01). Resistin and tumour necrosis factor-alpha expression was also reduced, though in the latter case, only with energy restriction (p < 0.05). Other adipokines were unaffected by RSG treatment. CONCLUSION Our results clearly show that energy restriction enhances the therapeutic efficacy of TZDs and suggest that this occurs, at least in part, through a modulatory effect on gene expression in visceral WAT. These findings improve our understanding of the underlying mechanistic basis for the clinical usefulness of dietary restriction as an adjunct to TZD therapy in type 2 diabetes.
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Affiliation(s)
- G B T Moore
- Department of Vascular Biology, GlaxoSmithKline, New Frontiers Science Park North, Harlow, Essex, UK
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Plomgaard P, Fischer CP, Ibfelt T, Pedersen BK, van Hall G. Tumor necrosis factor-alpha modulates human in vivo lipolysis. J Clin Endocrinol Metab 2008; 93:543-9. [PMID: 18029463 DOI: 10.1210/jc.2007-1761] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
CONTEXT Low-grade systemic inflammation is a feature of most lifestyle-related chronic diseases. Enhanced TNF-alpha concentrations have been implicated in the development of hyperlipidemia. OBJECTIVE We hypothesized that an acute elevation of TNF-alpha in plasma would cause an increase in lipolysis, increasing circulatory free fatty acid (FFA) levels. SUBJECTS AND METHODS Using a randomized controlled, crossover design, healthy young male individuals (n = 10) received recombinant human (rh) TNF-alpha (700 ng/m(-2).h(-1)) for 4 h, and energy metabolism was evaluated using a combination of tracer dilution methodology and arterial-venous differences over the leg. RESULTS Plasma TNF-alpha levels increased from 0.7 +/- 0.04 to 16.7 +/- 1.8 pg/ml, and plasma IL-6 increased from 1.0 +/- 0.2 to 9.2 +/- 1.0 pg/ml (P < 0.05) after 4-h rhTNF-alpha infusion. Here, we demonstrate that 4-h rhTNF-alpha infusion increases whole body lipolysis by 40% (P < 0.05) with a concomitant increase in FFA clearance, with no changes in skeletal muscle FFA uptake, release, or oxidation. Of note, systemic glucose turnover and lactate and catecholamine levels were unaffected by rhTNF-alpha infusion. CONCLUSION This study demonstrates that a relatively low dose of rhTNF-alpha induces systemic lipolysis and that the skeletal muscle fat metabolism is unaffected.
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Affiliation(s)
- Peter Plomgaard
- Centre of Inflammation and Metabolism, Department of Infectious Diseases, Faculty of Health Sciences, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark.
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OGASAWARA J, ABE T. Amino Acid Mixture Identical to Vespa Larval Saliva Increases both Leptin Secretion and Basal Lipolysis in Rat Adipocytes. FOOD SCIENCE AND TECHNOLOGY RESEARCH 2008. [DOI: 10.3136/fstr.14.95] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Kim SO. Ginseng Saponin-Re and Coix lachrymajobi var. mayuen Regulate Obesity Related Genes Expressions, TNF-alpha, Leptin, Lipoprotein Lipase and Resistin in 3T3-L1 Adipocytes. ACTA ACUST UNITED AC 2007. [DOI: 10.5352/jls.2007.17.11.1523] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Zu L, Jiang H, He J, Xu C, Pu S, Liu M, Xu G. Salicylate Blocks Lipolytic Actions of Tumor Necrosis Factor-α in Primary Rat Adipocytes. Mol Pharmacol 2007; 73:215-23. [PMID: 17911533 DOI: 10.1124/mol.107.039479] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Increased systemic free fatty acids (FFA) impair insulin sensitivity. In obese and diabetic subjects, production of tumor necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine, is elevated. TNF-alpha has a variety of effects by inducing inflammation, decreasing glucose utilization, and stimulating adipocyte lipolysis to release FFA to plasma. High doses of nonsteroidal anti-inflammatory drug salicylates have long been recognized to lower blood FFA and glucose in humans, although the mechanisms are not fully understood. In this report, we show that sodium salicylate at therapeutic concentrations directly blocks TNF-alpha-stimulated lipolysis and therefore inhibits FFA release from primary rat adipocytes. To elucidate the cellular basis of this action, we show that salicylate suppresses TNF-alpha-induced extracellular signal-related kinase activation and intracellular cAMP elevation, two early events during the lipolysis response to TNF-alpha. Furthermore, salicylate prevents the down-regulation of cyclic-nucleotide phosphodiesterase 3B, an enzyme responsible for cAMP hydrolysis. Perilipins coat intracellular lipid droplet surface by restricting lipase access to the triacylglycerol substrates. TNF-alpha down-regulates perilipin but promotes its phosphorylation during lipolysis stimulation; these actions are efficiently reversed by salicylate. Salicylate slightly reduces basal but completely inhibits TNF-alpha-liberated lipase activity. In contrast, neither salicylate nor TNF-alpha alters the protein levels of hormone-sensitive lipase and adipose triglyceride lipase. In addition, sodium salicylate restricts basal lipolysis simulated by a high concentration of glucose and significantly diminishes the high glucose-enhanced lipolysis response to TNF-alpha. These results provide novel evidence that salicylate directly blocks TNF-alpha-mediated FFA efflux from adipocytes, hence reducing plasma FFA levels and increasing insulin sensitivity.
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Affiliation(s)
- Luxia Zu
- Department of Physiology and Pathophysiology, Peking (Beijing) University Health Science Center, 38 Xueyuan Road, Beijing 100083, China.
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Rydén M, Arner P. Tumour necrosis factor-alpha in human adipose tissue -- from signalling mechanisms to clinical implications. J Intern Med 2007; 262:431-8. [PMID: 17875179 DOI: 10.1111/j.1365-2796.2007.01854.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
From its initial implication in the development of cachexia in the early 1980s, it is now almost 15 years ago that tumour necrosis factor-alpha (TNF-alpha) was first shown to be involved in the development of insulin resistance in obesity. Since the original findings in mice, a wealth of data has been obtained in a variety of settings and species. This intensive research has demonstrated both similarities and differences between rodents and humans regarding the molecular mechanisms and metabolic consequences of TNF-alpha overexpression. This review will focus on the role of TNF-alpha in human white adipose tissue with particular emphasis on its regulation of lipolysis - an important pathway in adipocytes which is linked to insulin-resistant phenotypes in obesity and the metabolic syndrome.
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Affiliation(s)
- M Rydén
- Department of Medicine (H7), Karolinska Institutet, Karolinska University Hospital at Huddinge, Stockholm, Sweden.
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