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Lin J, Zhu S, Liao Y, Liang Z, Quan Y, He Y, Cai J, Lu F. Spontaneous Browning of White Adipose Tissue Improves Angiogenesis and Reduces Macrophage Infiltration After Fat Grafting in Mice. Front Cell Dev Biol 2022; 10:845158. [PMID: 35557960 PMCID: PMC9087586 DOI: 10.3389/fcell.2022.845158] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/09/2022] [Indexed: 12/24/2022] Open
Abstract
Background: Fat grafting is a frequently used technique; however, its survival/ regeneration mechanism is not fully understood. The browning of white adipocytes, a process initiated in response to external stimuli, is the conversion of white to beige adipocytes. The physiologic significance of the browning of adipocytes following transplantation is unclear. Methods: C57BL/6 mice received 150 mg grafts of inguinal adipose tissue, and then the transplanted fat was harvested and analyzed at different time points to assess the browning process. To verify the role of browning of adipocytes in fat grafting, the recipient mice were allocated to three groups, which were administered CL316243 or SR59230A to stimulate or suppress browning, respectively, or a control group after transplantation. Results: Browning of the grafts was present in the center of each as early as 7 days post-transplantation. The number of beige cells peaked at day 14 and then decreased gradually until they were almost absent at day 90. The activation of browning resulted in superior angiogenesis, higher expression of the pro-angiogenic molecules vascular endothelial growth factor A (VEGF-A) and fibroblast growth factor 21 (FGF21), fewer macrophages, and ultimately better graft survival (Upregulation, 59.17% ± 6.64% vs. Control, 40.33% ± 4.03%, *p < 0.05), whereas the inhibition of browning led to poor angiogenesis, lower expression of VEGF-A, increased inflammatory macrophages, and poor transplant retention at week 10 (Downregulation, 20.67% ± 3.69% vs. Control, 40.33% ± 4.03%, *p < 0.05). Conclusion: The browning of WAT following transplantation improves the survival of fat grafts by the promotion of angiogenesis and reducing macrophage.
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Affiliation(s)
| | | | | | | | | | | | | | - Feng Lu
- *Correspondence: Junrong Cai, ; Feng Lu,
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2
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Agueda-Oyarzabal M, Emanuelli B. Immune Cells in Thermogenic Adipose Depots: The Essential but Complex Relationship. Front Endocrinol (Lausanne) 2022; 13:839360. [PMID: 35360060 PMCID: PMC8963988 DOI: 10.3389/fendo.2022.839360] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 01/28/2022] [Indexed: 01/09/2023] Open
Abstract
Brown adipose tissue (BAT) is a unique organ in mammals capable of dissipating energy in form of heat. Additionally, white adipose tissue (WAT) can undergo browning and perform thermogenesis. In recent years, the research community has aimed to harness thermogenic depot functions for new therapeutic strategies against obesity and the metabolic syndrome; hence a comprehensive understanding of the thermogenic fat microenvironment is essential. Akin to WAT, immune cells also infiltrate and reside within the thermogenic adipose tissues and perform vital functions. As highly plastic organs, adipose depots rely on crucial interplay with these tissue resident cells to conserve their healthy state. Evidence has accumulated to show that different immune cell populations contribute to thermogenic adipose tissue homeostasis and activation through complex communicative networks. Furthermore, new studies have identified -but still not fully characterized further- numerous immune cell populations present in these depots. Here, we review the current knowledge of this emerging field by describing the immune cells that sway the thermogenic adipose depots, and the complex array of communications that influence tissue performance.
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3
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Leiva M, Matesanz N, Pulgarín-Alfaro M, Nikolic I, Sabio G. Uncovering the Role of p38 Family Members in Adipose Tissue Physiology. Front Endocrinol (Lausanne) 2020; 11:572089. [PMID: 33424765 PMCID: PMC7786386 DOI: 10.3389/fendo.2020.572089] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 11/17/2020] [Indexed: 12/12/2022] Open
Abstract
The complex functions of adipose tissue have been a focus of research interest over the past twenty years. Adipose tissue is not only the main energy storage depot, but also one of the largest endocrine organs in the body and carries out crucial metabolic functions. Moreover, brown and beige adipose depots are major sites of energy expenditure through the activation of adaptive, non-shivering thermogenesis. In recent years, numerous signaling molecules and pathways have emerged as critical regulators of adipose tissue, in both homeostasis and obesity-related disease. Among the best characterized are members of the p38 kinase family. The activity of these kinases has emerged as a key contributor to the biology of the white and brown adipose tissues, and their modulation could provide new therapeutic approaches against obesity. Here, we give an overview of the roles of the distinct p38 family members in adipose tissue, focusing on their actions in adipogenesis, thermogenic activity, and secretory function.
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4
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Summerfield M, Zhou Y, Zhou T, Wu C, Alpini G, Zhang KK, Xie L. A long-term maternal diet transition from high-fat diet to normal fat diet during pre-pregnancy avoids adipose tissue inflammation in next generation. PLoS One 2018; 13:e0209053. [PMID: 30562363 PMCID: PMC6298692 DOI: 10.1371/journal.pone.0209053] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 11/27/2018] [Indexed: 12/11/2022] Open
Abstract
Recent studies have suggested that maternal high-fat (HF) diet caused inflammation changes in adipose tissue; however, it remains unclear if maternal diet intervention before pregnancy rescues such effects in offspring. To address this question, female mice were continued on a normal-fat (NF group), or a HF diet (HF group) or transitioned from a HF diet to a NF diet at 1 (H1N group), 5 (H5N group) or 9 weeks (H9N group) prior to pregnancy. Among the three intervention groups, the H9N offspring displayed less and steady body weight gain, and maintained glucose tolerance, whereas the H1N and H5N offspring showed exacerbate these phenotypes. The H1N and H5N, but not the H9N offspring, displayed adipocyte hypertrophy associated with increased expression of genes involved in fat deposition. The H1N and H5N, but not the H9N adipose tissue, displayed increased macrophage infiltration with enhanced expression of inflammatory cytokine genes. In addition, overactivation of the NF-κB and the JNK signaling were observed in the H1N adipose tissue. Overall, our study showed that a long-term but not a short- or medium-term diet intervention before pregnancy released offspring adipose tissue inflammation induced by maternal HF diet, which adds details in our understanding how the maternal environment either promotes or discourages onset of disease in offspring. Clinically, this study is of great value for providing evidence in the design of clinical trials to evaluate the urgently required intervention strategies to minimize the intergenerational cycle of obesity.
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Affiliation(s)
- Michelle Summerfield
- Department of Nutrition and Food Sciences, Texas A&M University, College Station, TX, United States of America
| | - Yi Zhou
- Department of Nutrition and Food Sciences, Texas A&M University, College Station, TX, United States of America
- Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Tianhao Zhou
- Department of Medical Physiology, Texas A&M University College of Medicine, Temple, TX, United States of America
| | - Chaodong Wu
- Department of Nutrition and Food Sciences, Texas A&M University, College Station, TX, United States of America
| | - Gianfranco Alpini
- Department of Medical Physiology, Texas A&M University College of Medicine, Temple, TX, United States of America
- Research, Central Texas Veterans Health Care System, Temple, TX, United States of America
| | - Ke K. Zhang
- Department of Nutrition and Food Sciences, Texas A&M University, College Station, TX, United States of America
- Center for Epigenetics & Disease Prevention, Institute of Biosciences & Technology, College of Medicine, Texas A&M University, Houston, TX, United States of America
| | - Linglin Xie
- Department of Nutrition and Food Sciences, Texas A&M University, College Station, TX, United States of America
- * E-mail:
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5
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François M, Qualls-Creekmore E, Berthoud HR, Münzberg H, Yu S. Genetics-based manipulation of adipose tissue sympathetic innervation. Physiol Behav 2017; 190:21-27. [PMID: 28859876 DOI: 10.1016/j.physbeh.2017.08.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/25/2017] [Accepted: 08/26/2017] [Indexed: 12/17/2022]
Abstract
There is renewed interest in leveraging the thermogenic capacity of brown adipose tissue (BAT) and browning of white adipose tissue (WAT) to improve energy balance and prevent obesity. In addition to these effects on energy expenditure, both BAT and WAT secrete large numbers of hormones and cytokines that play important roles in maintaining metabolic health. Both BAT and WAT are densely innervated by the sympathetic nervous system (SNS) and this innervation is crucial for BAT thermogenesis and WAT browning, making it a potentially interesting target for manipulating energy balance and treatment of obesity and metabolic disease. Peripheral neuromodulation in the form of electrical manipulation of the SNS and parasympathetic nervous system (PSNS) has been used for the management of pain and many other conditions, but progress is hampered by lack of detailed knowledge of function-specific neurons and nerves innervating particular organs and tissues. Therefore, the goal of the National Institutes of Health (NIH) Common Fund project "Stimulating Peripheral Activity to Relieve Conditions (SPARC)" is to comprehensively map both anatomical and neurochemical aspects of the peripheral nervous system in animal model systems to ultimately guide optimal neuromodulation strategies in humans. Compared to electrical manipulation, neuron-specific opto- and chemogenetic manipulation, now being extensively used to decode the function of brain circuits, will further increase the functional specificity of peripheral neuromodulation.
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Affiliation(s)
- Marie François
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, USA
| | - Emily Qualls-Creekmore
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, USA
| | - Hans-Rudolf Berthoud
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, USA
| | - Heike Münzberg
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, USA
| | - Sangho Yu
- Neurobiology of Nutrition and Metabolism Department, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, USA.
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6
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Intrinsic Properties of Brown and White Adipocytes Have Differential Effects on Macrophage Inflammatory Responses. Mediators Inflamm 2017; 2017:9067049. [PMID: 28458470 PMCID: PMC5385256 DOI: 10.1155/2017/9067049] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 01/31/2017] [Accepted: 02/12/2017] [Indexed: 12/13/2022] Open
Abstract
Obesity is marked by chronic, low-grade inflammation. Here, we examined whether intrinsic differences between white and brown adipocytes influence the inflammatory status of macrophages. White and brown adipocytes were characterized by transcriptional regulation of UCP-1, PGC1α, PGC1β, and CIDEA and their level of IL-6 secretion. The inflammatory profile of PMA-differentiated U937 and THP-1 macrophages, in resting state and after stimulation with LPS/IFN-gamma and IL-4, was assessed by measuring IL-6 secretion and transcriptional regulation of a panel of inflammatory genes after mono- or indirect coculture with white and brown adipocytes. White adipocyte monocultures show increased IL-6 secretion compared to brown adipocytes. White adipocytes cocultured with U937 and THP-1 macrophages induced a greater increase in IL-6 secretion compared to brown adipocytes cocultured with both macrophages. White adipocytes cocultured with macrophages increased inflammatory gene expression in both types. In contrast, macrophages cocultured with brown adipocytes induced downregulation or no alterations in inflammatory gene expression. The effects of adipocytes on macrophages appear to be independent of stimulation state. Brown adipocytes exhibit an intrinsic ability to dampen inflammatory profile of macrophages, while white adipocytes enhance it. These data suggest that brown adipocytes may be less prone to adipose tissue inflammation that is associated with obesity.
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Xie L, Zhang K, Rasmussen D, Wang J, Wu D, Roemmich JN, Bundy A, Johnson WT, Claycombe K. Effects of prenatal low protein and postnatal high fat diets on visceral adipose tissue macrophage phenotypes and IL-6 expression in Sprague Dawley rat offspring. PLoS One 2017; 12:e0169581. [PMID: 28141871 PMCID: PMC5283658 DOI: 10.1371/journal.pone.0169581] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 12/19/2016] [Indexed: 01/05/2023] Open
Abstract
Adipose tissue macrophages (ATM) are implicated in adipose tissue inflammation and obesity-related insulin resistance. Maternal low protein models result in fetal programming of obesity. The study aims to answer whether maternal undernutrition by protein restriction affects the ATM M1 or M2 phenotype under postnatal high fat diet in F1 offspring. Using a rat model of prenatal low protein (LP, 8% protein) diet followed by a postnatal high fat energy diet (HE, 45% fat) or low fat normal energy diet (NE, 10% fat) for 12 weeks, we investigated the effects of these diets on adiposity, programming of the offspring ATM phenotype, and the associated inflammatory response in adipose tissue. Fat mass in newborn and 12-week old LP fed offspring was lower than that of normal protein (20%; NP) fed offspring; however, the adipose tissue growth rate was higher compared to the NP fed offspring. While LP did not affect the number of CD68+ or CD206+ cells in adipose tissue of NE offspring, it attenuated the number of these cells in offspring fed HE. In offspring fed HE, LP offspring had a lower percentage of CD11c+CD206+ ATMs, whose abundancy was correlated with the size of the adipocytes. Noteworthy, similar to HE treatment, LP increased gene expression of IL-6 within ATMs. Two-way ANOVA showed an interaction of prenatal LP and postnatal HE on IL-6 and IL-1β transcription. Overall, both LP and HE diets impact ATM phenotype by affecting the ratio of CD11c+CD206+ ATMs and the expression of IL-6.
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Affiliation(s)
- Linglin Xie
- Department of Nutrition and Food Sciences, Texas A&M University, College Station, Texas, United States of America
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
- * E-mail: (LX); (KJC)
| | - Ke Zhang
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
- ND INBRE Bioinformatics Core, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Dane Rasmussen
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Junpeng Wang
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts, United States of America
| | - Dayong Wu
- Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts, United States of America
| | - James N. Roemmich
- USDA Agricultural Research Service, Grand Forks Human Nutrition Research Center, Grand Forks, North Dakota, United States of America
| | - Amy Bundy
- USDA Agricultural Research Service, Grand Forks Human Nutrition Research Center, Grand Forks, North Dakota, United States of America
| | - W. Thomas Johnson
- USDA Agricultural Research Service, Grand Forks Human Nutrition Research Center, Grand Forks, North Dakota, United States of America
| | - Kate Claycombe
- USDA Agricultural Research Service, Grand Forks Human Nutrition Research Center, Grand Forks, North Dakota, United States of America
- * E-mail: (LX); (KJC)
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8
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The Role of Tissue Macrophage-Mediated Inflammation on NAFLD Pathogenesis and Its Clinical Implications. Mediators Inflamm 2017; 2017:8162421. [PMID: 28115795 PMCID: PMC5237469 DOI: 10.1155/2017/8162421] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 11/22/2016] [Accepted: 12/04/2016] [Indexed: 02/06/2023] Open
Abstract
The obese phenotype is characterized by a state of chronic low-grade systemic inflammation that contributes to the development of comorbidities, including nonalcoholic fatty liver disease (NAFLD). In fact, NAFLD is often associated with adipocyte enlargement and consequent macrophage recruitment and inflammation. Macrophage polarization is often associated with the proinflammatory state in adipose tissue. In particular, an increase of M1 macrophages number or of M1/M2 ratio triggers the production and secretion of various proinflammatory signals (i.e., adipocytokines). Next, these inflammatory factors may reach the liver leading to local M1/M2 macrophage polarization and consequent onset of the histological damage characteristic of NAFLD. Thus, the role of macrophage polarization and inflammatory signals appears to be central for pathogenesis and progression of NAFLD, even if the heterogeneity of macrophages and molecular mechanisms that govern their phenotype switch remain incompletely understood. In this review, we discuss the role of adipose and liver tissue macrophage-mediated inflammation in experimental and human NAFLD. This focus is relevant because it may help researchers that approach clinical and experimental studies on this disease advancing the knowledge of mechanisms that could be targeted in order to revert NAFLD-related fibrosis.
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9
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Abstract
Brown adipose tissue (BAT) is the main site of adaptive thermogenesis and experimental studies have associated BAT activity with protection against obesity and metabolic diseases, such as type 2 diabetes mellitus and dyslipidaemia. Active BAT is present in adult humans and its activity is impaired in patients with obesity. The ability of BAT to protect against chronic metabolic disease has traditionally been attributed to its capacity to utilize glucose and lipids for thermogenesis. However, BAT might also have a secretory role, which could contribute to the systemic consequences of BAT activity. Several BAT-derived molecules that act in a paracrine or autocrine manner have been identified. Most of these factors promote hypertrophy and hyperplasia of BAT, vascularization, innervation and blood flow, processes that are all associated with BAT recruitment when thermogenic activity is enhanced. Additionally, BAT can release regulatory molecules that act on other tissues and organs. This secretory capacity of BAT is thought to be involved in the beneficial effects of BAT transplantation in rodents. Fibroblast growth factor 21, IL-6 and neuregulin 4 are among the first BAT-derived endocrine factors to be identified. In this Review, we discuss the current understanding of the regulatory molecules (the so-called brown adipokines or batokines) that are released by BAT that influence systemic metabolism and convey the beneficial metabolic effects of BAT activation. The identification of such adipokines might also direct drug discovery approaches for managing obesity and its associated chronic metabolic diseases.
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Affiliation(s)
- Francesc Villarroya
- Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina, Universitat de Barcelona, Avda Diagonal 643, 08028-Barcelona, Catalonia, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición, Facultat de Biologia, Universitat de Barcelona, Avda Diagonal 643, 08028-Barcelona, Catalonia, Spain
| | - Rubén Cereijo
- CIBER Fisiopatología de la Obesidad y Nutrición, Facultat de Biologia, Universitat de Barcelona, Avda Diagonal 643, 08028-Barcelona, Catalonia, Spain
| | - Joan Villarroya
- CIBER Fisiopatología de la Obesidad y Nutrición, Facultat de Biologia, Universitat de Barcelona, Avda Diagonal 643, 08028-Barcelona, Catalonia, Spain
| | - Marta Giralt
- Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina, Universitat de Barcelona, Avda Diagonal 643, 08028-Barcelona, Catalonia, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición, Facultat de Biologia, Universitat de Barcelona, Avda Diagonal 643, 08028-Barcelona, Catalonia, Spain
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Gómez-Hernández A, Beneit N, Díaz-Castroverde S, Escribano Ó. Differential Role of Adipose Tissues in Obesity and Related Metabolic and Vascular Complications. Int J Endocrinol 2016; 2016:1216783. [PMID: 27766104 PMCID: PMC5059561 DOI: 10.1155/2016/1216783] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 07/19/2016] [Accepted: 08/04/2016] [Indexed: 12/18/2022] Open
Abstract
This review focuses on the contribution of white, brown, and perivascular adipose tissues to the pathophysiology of obesity and its associated metabolic and vascular complications. Weight gain in obesity generates excess of fat, usually visceral fat, and activates the inflammatory response in the adipocytes and then in other tissues such as liver. Therefore, low systemic inflammation responsible for insulin resistance contributes to atherosclerotic process. Furthermore, an inverse relationship between body mass index and brown adipose tissue activity has been described. For these reasons, in recent years, in order to combat obesity and its related complications, as a complement to conventional treatments, a new insight is focusing on the role of the thermogenic function of brown and perivascular adipose tissues as a promising therapy in humans. These lines of knowledge are focused on the design of new drugs, or other approaches, in order to increase the mass and/or activity of brown adipose tissue or the browning process of beige cells from white adipose tissue. These new treatments may contribute not only to reduce obesity but also to prevent highly prevalent complications such as type 2 diabetes and other vascular alterations, such as hypertension or atherosclerosis.
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Affiliation(s)
- Almudena Gómez-Hernández
- Biochemistry and Molecular Biology Department, School of Pharmacy, Complutense University of Madrid, Madrid, Spain
- CIBER of Diabetes and Associated Metabolic Diseases, Madrid, Spain
- Instituto de Investigación Sanitaria Hospital Clínico San Carlos, IdISSC, Instituto de Salud Carlos III, Madrid, Spain
| | - Nuria Beneit
- Biochemistry and Molecular Biology Department, School of Pharmacy, Complutense University of Madrid, Madrid, Spain
- CIBER of Diabetes and Associated Metabolic Diseases, Madrid, Spain
- Instituto de Investigación Sanitaria Hospital Clínico San Carlos, IdISSC, Instituto de Salud Carlos III, Madrid, Spain
| | - Sabela Díaz-Castroverde
- Biochemistry and Molecular Biology Department, School of Pharmacy, Complutense University of Madrid, Madrid, Spain
- CIBER of Diabetes and Associated Metabolic Diseases, Madrid, Spain
- Instituto de Investigación Sanitaria Hospital Clínico San Carlos, IdISSC, Instituto de Salud Carlos III, Madrid, Spain
| | - Óscar Escribano
- Biochemistry and Molecular Biology Department, School of Pharmacy, Complutense University of Madrid, Madrid, Spain
- CIBER of Diabetes and Associated Metabolic Diseases, Madrid, Spain
- Instituto de Investigación Sanitaria Hospital Clínico San Carlos, IdISSC, Instituto de Salud Carlos III, Madrid, Spain
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Pravenec M, Mlejnek P, Zídek V, Landa V, Šimáková M, Šilhavý J, Strnad H, Eigner S, Eigner Henke K, Škop V, Malínská H, Trnovská J, Kazdová L, Drahota Z, Mráček T, Houštěk J. Autocrine effects of transgenic resistin reduce palmitate and glucose oxidation in brown adipose tissue. Physiol Genomics 2016; 48:420-7. [PMID: 27113533 DOI: 10.1152/physiolgenomics.00122.2015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 04/06/2016] [Indexed: 12/23/2022] Open
Abstract
Resistin has been originally identified as an adipokine that links obesity to insulin resistance in mice. In our previous studies in spontaneously hypertensive rats (SHR) expressing a nonsecreted form of mouse resistin (Retn) transgene specifically in adipose tissue (SHR-Retn), we have observed an increased lipolysis and serum free fatty acids, ectopic fat accumulation in muscles, and insulin resistance. Recently, brown adipose tissue (BAT) has been suggested to play an important role in the pathogenesis of metabolic disturbances. In the current study, we have analyzed autocrine effects of transgenic resistin on BAT glucose and lipid metabolism and mitochondrial function in the SHR-Retn vs. nontransgenic SHR controls. We observed that interscapular BAT isolated from SHR-Retn transgenic rats compared with SHR controls showed a lower relative weight (0.71 ± 0.05 vs. 0.91 ± 0.08 g/100 g body wt, P < 0.05), significantly reduced both basal and insulin stimulated incorporation of palmitate into BAT lipids (658 ± 50 vs. 856 ± 45 and 864 ± 47 vs. 1,086 ± 35 nmol/g/2 h, P ≤ 0.01, respectively), and significantly decreased palmitate oxidation (37.6 ± 4.5 vs. 57 ± 4.1 nmol/g/2 h, P = 0.007) and glucose oxidation (277 ± 34 vs. 458 ± 38 nmol/g/2 h, P = 0.001). In addition, in vivo microPET imaging revealed significantly reduced (18)F-FDG uptake in BAT induced by exposure to cold in SHR-Retn vs. control SHR (232 ± 19 vs. 334 ± 22 kBq/ml, P < 0.05). Gene expression profiles in BAT identified differentially expressed genes involved in skeletal muscle and connective tissue development, inflammation and MAPK and insulin signaling. These results provide evidence that autocrine effects of resistin attenuate differentiation and activity of BAT and thus may play a role in the pathogenesis of insulin resistance in the rat.
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Affiliation(s)
- Michal Pravenec
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic;
| | - Petr Mlejnek
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Václav Zídek
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Vladimír Landa
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Miroslava Šimáková
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Jan Šilhavý
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Hynek Strnad
- Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic
| | - Sebastian Eigner
- Nuclear Physics Institute, Czech Academy of Sciences, Husinec-Řež, Czech Republic, Faculty of Pharmacy, Charles University in Prague, Hradec Králové, Czech Republic
| | | | - Vojtěch Škop
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic
| | - Hana Malínská
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic
| | - Jaroslava Trnovská
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic
| | - Ludmila Kazdová
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic
| | - Zdeněk Drahota
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Tomáš Mráček
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Josef Houštěk
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
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Tran MTN, Hamada M, Nakamura M, Jeon H, Kamei R, Tsunakawa Y, Kulathunga K, Lin YY, Fujisawa K, Kudo T, Takahashi S. MafB deficiency accelerates the development of obesity in mice. FEBS Open Bio 2016; 6:540-7. [PMID: 27419056 PMCID: PMC4887969 DOI: 10.1002/2211-5463.12058] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 02/12/2016] [Accepted: 03/14/2016] [Indexed: 12/28/2022] Open
Abstract
MafB, a transcription factor expressed selectively in macrophages, has important roles in some macrophage-related diseases, especially in atherosclerosis. In this study, we investigated the mechanism by which hematopoietic-specific MafB deficiency induces the development of obesity. Wild-type and hematopoietic cell-specific Mafb-deficient mice were fed a high-fat diet for 10 weeks. The Mafb-deficient mice exhibited higher body weights and faster rates of body weight increase than control mice. The Mafb-deficient mice also had a higher percentage of body fat than the wild-type mice, due to increased adipocyte size and serum cholesterol levels. Reverse transcription-PCR analysis showed a reduction in apoptosis inhibitor of macrophage (AIM) in Mafb-deficient adipose tissue. AIM is known as an inhibitor of lipogenesis in adipocytes and is expressed in adipose tissue macrophages. Collectively, our data suggest that Mafb deficiency in hematopoietic cells accelerates the development of obesity.
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Affiliation(s)
- Mai Thi Nhu Tran
- Department of Anatomy and Embryology Faculty of Medicine University of Tsukuba Ibaraki Japan
| | - Michito Hamada
- Department of Anatomy and Embryology Faculty of Medicine University of Tsukuba Ibaraki Japan; Laboratory Animal Resource Center Faculty of Medicine University of Tsukuba Ibaraki Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) University of Tsukuba Ibaraki Japan
| | - Megumi Nakamura
- Department of Anatomy and Embryology Faculty of Medicine University of Tsukuba Ibaraki Japan
| | - Hyojung Jeon
- Department of Anatomy and Embryology Faculty of Medicine University of Tsukuba Ibaraki Japan
| | - Risa Kamei
- Department of Anatomy and Embryology Faculty of Medicine University of Tsukuba Ibaraki Japan
| | - Yuki Tsunakawa
- Department of Anatomy and Embryology Faculty of Medicine University of Tsukuba Ibaraki Japan; Ph.D. Program in Human Biology School of Integrative and Global Majors University of Tsukuba Ibaraki Japan
| | - Kaushalya Kulathunga
- Department of Anatomy and Embryology Faculty of Medicine University of Tsukuba Ibaraki Japan; Ph.D. Program in Human Biology School of Integrative and Global Majors University of Tsukuba Ibaraki Japan
| | - Yuan-Yu Lin
- Laboratory of Molecular Biology Department of Animal Science and Technology National Taiwan University Taipei Taiwan
| | - Kumiko Fujisawa
- Department of Anatomy and Embryology Faculty of Medicine University of Tsukuba Ibaraki Japan
| | - Takashi Kudo
- Department of Anatomy and Embryology Faculty of Medicine University of Tsukuba Ibaraki Japan; Laboratory Animal Resource Center Faculty of Medicine University of Tsukuba Ibaraki Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) University of Tsukuba Ibaraki Japan
| | - Satoru Takahashi
- Department of Anatomy and Embryology Faculty of Medicine University of Tsukuba Ibaraki Japan; Laboratory Animal Resource Center Faculty of Medicine University of Tsukuba Ibaraki Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) University of Tsukuba Ibaraki Japan
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13
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Abstract
The adipose tissue (AT) is multifunctional, acting as an endocrine tissue and participating in the regulation of the organism's homeostasis. Metabolic, endocrine and inflammatory mechanisms are tightly intertwined within the AT, regulating its function. Disruption of the equilibrium among these mechanisms leads to pathologies, the most common being obesity-related insulin resistance. Two types of AT exist, the white and the brown AT. Traditionally the white AT (WAT) was thought to store energy in the form of lipids, while the brown AT (BAT) was known to mediate heat generation. Recently, the 'brite' or 'beige' AT was identified, which is localized predominantly in subcutaneous WAT, but shares functional features with the BAT and is capable of heat production. The major stimulus triggering beige and brown adipogenesis is cold exposure and catecholamine signalling. However, several further signals and mechanisms exist, which can orchestrate and fine-tune beige and brown AT function. Immune cells and inflammation have emerged as regulators of beige and brown AT function. The present review will focus on the recently identified crosstalk between innate immunity and the regulation of beige and brown adipogenesis.
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Affiliation(s)
- Vasileia Ismini Alexaki
- Department of Clinical Pathobiochemistry, Medical Faculty, Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany.
| | - Triantafyllos Chavakis
- Department of Clinical Pathobiochemistry, Medical Faculty, Technische Universität Dresden, Fetscherstrasse 74, 01307, Dresden, Germany
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at University Hospital and Faculty of Medicine, TU Dresden, Dresden, Germany
- German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany
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14
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Affiliation(s)
- Salvatore Chirumbolo
- Head of the Laboratory of Physioparthology of Obesity, Department of Medicine-Section of Geriatry, University of Verona
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15
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Establishment and characterization of DB-1: a leptin receptor-deficient murine macrophage cell line. Cytotechnology 2015; 68:921-33. [PMID: 25599862 DOI: 10.1007/s10616-015-9843-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 12/31/2014] [Indexed: 12/14/2022] Open
Abstract
Metabolic and immune mediators activate many of the same signal transduction pathways. Therefore, molecules that regulate metabolism often affect immune responses. Leptin is an adipokine that exemplifies this interplay. Leptin is the body's major nutritional status sensor, but it also plays a key role in immune system regulation. To provide an in vitro tool to investigate the link between leptin and innate immunity, we immortalized and characterized a leptin receptor-deficient macrophage cell line, DB-1. The cell line was created using bone marrow cells from leptin receptor-deficient mice. Bone marrow cells were differentiated into macrophages by culturing them with recombinant mouse macrophage colony stimulating factor, and passaged when confluent for 6 months. The cells spontaneously immortalized at approximately passage 20. Cells were cloned twice by limiting dilution cloning prior to characterization. The macrophage cell line is diploid and grows at a linear rate for 4-5 days before reaching the growth plateau. The cells are MAC-2 and F4/80 positive and have phagocytic activity similar to primary macrophages from wild-type and leptin receptor-deficient mice. DB-1 cells were responsive to stimulation with interferon-γ as measured by increase in Nos2 transcript levels. In addition, DB-1 macrophages are not responsive to the chemotactic signaling of adipocyte conditioned media nor leptin when compared to primary WT macrophages. We believe that DB-1 cells provide a dependable tool to study the role of leptin or the leptin receptor in obesity-associated inflammation and immune system dysregulation.
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16
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Xie L, Fu Q, Ortega TM, Zhou L, Rasmussen D, O’Keefe J, Zhang KK, Chapes SK. Overexpression of IL-10 in C2D macrophages promotes a macrophage phenotypic switch in adipose tissue environments. PLoS One 2014; 9:e86541. [PMID: 24466141 PMCID: PMC3897709 DOI: 10.1371/journal.pone.0086541] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 12/14/2013] [Indexed: 11/19/2022] Open
Abstract
Adipose tissue macrophages are a heterogeneous collection of classically activated (M1) and alternatively activated (M2) macrophages. Interleukin 10 (IL-10) is an anti-inflammatory cytokine, secreted by a variety of cell types including M2 macrophages. We generated a macrophage cell line stably overexpressing IL-10 (C2D-IL10) and analyzed the C2D-IL10 cells for several macrophage markers after exposure to adipocytes compared to C2D cells transfected with an empty vector (C2D-vector). C2D-IL10 macrophage cells expressed more CD206 when co-cultured with adipocytes than C2D-vector cells; while the co-cultured cell mixture also expressed higher levels of Il4, Il10, Il1β and Tnf. Since regular C2D cells traffic to adipose tissue after adoptive transfer, we explored the impact of constitutive IL-10 expression on C2D-IL10 macrophages in adipose tissue in vivo. Adipose tissue-isolated C2D-IL10 cells increased the percentage of CD206(+), CD301(+), CD11c(-)CD206(+) (M2) and CD11c(+)CD206(+) (M1b) on their cell surface, compared to isolated C2D-vector cells. These data suggest that the expression of IL-10 remains stable, alters the C2D-IL10 macrophage cell surface phenotype and may play a role in regulating macrophage interactions with the adipose tissue.
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Affiliation(s)
- Linglin Xie
- Department of Basic Sciences, School of Medicine and Health Science, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Qiang Fu
- Department of Basic Sciences, School of Medicine and Health Science, University of North Dakota, Grand Forks, North Dakota, United States of America
- Departments of Gerontology and Oncology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Teresa M. Ortega
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
| | - Lun Zhou
- Department of Basic Sciences, School of Medicine and Health Science, University of North Dakota, Grand Forks, North Dakota, United States of America
- Departments of Gerontology and Oncology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, China
| | - Dane Rasmussen
- Department of Basic Sciences, School of Medicine and Health Science, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Jacy O’Keefe
- Department of Basic Sciences, School of Medicine and Health Science, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Ke K. Zhang
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
- North Dakota IDeA Network of Biomedical Research Excellence Bioinformatics Core, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Stephen K. Chapes
- Division of Biology, Kansas State University, Manhattan, Kansas, United States of America
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Dib LH, Ortega MT, Fleming SD, Chapes SK, Melgarejo T. Bone marrow leptin signaling mediates obesity-associated adipose tissue inflammation in male mice. Endocrinology 2014; 155:40-6. [PMID: 24169547 PMCID: PMC3868799 DOI: 10.1210/en.2013-1607] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Obesity is characterized by an increased recruitment of proinflammatory macrophages to the adipose tissue (AT), leading to systemic inflammation and metabolic disease. The pathogenesis of this AT inflammation, however, remains to be elucidated. The circulating adipokine leptin is increased in obesity and is involved in immune cell function and activation. In the present study, we investigated the role of leptin in the induction of obesity-associated inflammation. We generated radiation chimeric C57BL/6J mice reconstituted with either leptin receptor-deficient (db/db) or wild-type (WT) bone marrow and challenged them with a high-fat diet (HFD) for 16 weeks. Mice reconstituted with db/db bone marrow (WT/db), had significantly lower body weight and adiposity compared with mice with WT bone marrow (WT/WT). Gonadal AT in WT/db mice displayed a 2-fold lower expression of the inflammatory genes Tnfa, Il6, and Ccl2. In addition, gonadal fat of WT/db mice contained significantly fewer crown-like structures compared with WT/WT mice, and most of their AT macrophages expressed macrophage galactose-type C type lectin 1 (MGL1) and were C-C chemokine receptor type 2 (CCR2)-negative, indicative of an anti-inflammatory phenotype. Moreover, WT/db mice exhibited greater insulin sensitivity compared with WT/WT mice. These data show that disrupted leptin signaling in bone marrow-derived cells attenuates the proinflammatory conditions that mediate many of the metabolic complications that characterize obesity. Our findings establish a novel mechanism involved in the regulation of obesity-associated systemic inflammation and support the hypothesis that leptin is a proinflammatory cytokine.
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18
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Abstract
White adipose tissue is recognized as both a site of energy storage and an endocrine organ that produces a myriad of endocrine factors called adipokines. Brown adipose tissue (BAT) is the main site of nonshivering thermogenesis in mammals. The amount and activity of brown adipocytes are associated with protection against obesity and associated metabolic alterations. These effects of BAT are traditionally attributed to its capacity for the oxidation of fatty acids and glucose to sustain thermogenesis. However, recent data suggest that the beneficial effects of BAT could involve a previously unrecognized endocrine role through the release of endocrine factors. Several signaling molecules with endocrine properties have been found to be released by brown fat, especially under conditions of thermogenic activation. Moreover, experimental BAT transplantation has been shown to improve glucose tolerance and insulin sensitivity mainly by influencing hepatic and cardiac function. It has been proposed that these effects are due to the release of endocrine factors by brown fat, such as insulin-like growth factor I, interleukin-6, or fibroblast growth factor-21. Further research is needed to determine whether brown fat plays an endocrine role and, if so, to comprehensively identify which endocrine factors are released by BAT. Such research may reveal novel clues for the observed association between brown adipocyte activity and a healthy metabolic profile, and it could also enlarge a current view of potential therapeutic tools for obesity and associated metabolic diseases.
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19
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Giorgio S. Macrophages: plastic solutions to environmental heterogeneity. Inflamm Res 2013; 62:835-43. [DOI: 10.1007/s00011-013-0647-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 07/05/2013] [Indexed: 12/14/2022] Open
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Gómez-Hernández A, Perdomo L, Escribano Ó, Benito M. [Role of brown and perivascular adipose tissue in vascular complications due to obesity]. CLINICA E INVESTIGACION EN ARTERIOSCLEROSIS : PUBLICACION OFICIAL DE LA SOCIEDAD ESPANOLA DE ARTERIOSCLEROSIS 2013; 25:36-44. [PMID: 23522280 DOI: 10.1016/j.arteri.2012.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 11/28/2012] [Indexed: 06/02/2023]
Abstract
The contribution of brown and perivascular adipose tissues to the pathophysiology of metabolic and vascular complications associated with obesity are analysed in this review. To combat obesity and prevent its highly prevalent metabolic and vascular complications, a new insight on our knowledge of the role of the thermogenic function of brown adipose tissue and its promising therapeutic potential in humans is needed in addition to conventional treatments. Owing to the impact of brown adipose tissue on energy expenditure related to lipid and glucose metabolism, as well as its potential resistance against inflammation along with perivascular adipose tissue, new perspectives in the treatment of obesity treatment could be focused on the design of new drugs, or different regimens or therapies, that increase the amount and activity of brown adipose tissue. These new treatments not only may contribute to combat obesity, but also prevent complications such as type 2 diabetes and other associated metabolic and vascular changes.
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Affiliation(s)
- Almudena Gómez-Hernández
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, España.
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21
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Chatzigeorgiou A, Karalis KP, Bornstein SR, Chavakis T. Lymphocytes in obesity-related adipose tissue inflammation. Diabetologia 2012; 55:2583-2592. [PMID: 22733483 DOI: 10.1007/s00125-012-2607-0] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 05/17/2012] [Indexed: 12/17/2022]
Abstract
Inflammation in the white adipose tissue (WAT) is considered a major player in the development of insulin resistance. The role of macrophages accumulating in the WAT during obesity, promoting WAT inflammation and insulin resistance is well established. In contrast, less is known about the role of lymphocytes. Recent studies have implicated different lymphocyte subsets in WAT inflammation. For instance, cytotoxic CD8(+) T cells infiltrating the WAT may contribute to the recruitment, differentiation and activation of macrophages. On the other hand, a differential role for CD4(+) Th1 and CD4(+) Th2 cells has been suggested. Levels of WAT regulatory T cells decrease during the course of obesity and may represent a crucial factor for the maintenance of insulin sensitivity. Moreover, activation of natural killer T cells, an innate-like T cell population, which recognises lipid antigens, promotes insulin resistance and WAT inflammation. Finally, B cells may infiltrate WAT very early in response to high-fat feeding and worsen glucose metabolism through modulation of T cells and the production of pathogenic antibodies. These interesting new findings however bear controversies and introduce novel, yet unanswered, questions. Here, we review and discuss the impact of the different lymphocyte subsets in obesity-related WAT inflammation and attempt to identify the open questions to be answered by future studies.
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Affiliation(s)
- A Chatzigeorgiou
- Department of Internal Medicine III, Division of Vascular Inflammation, Diabetes and Kidney, University Clinic Carl-Gustav-Carus, University of Dresden, Fetscherstrasse 74, 01307, Dresden, Germany.
- Institute of Physiology, University of Dresden, Dresden, Germany.
| | - K P Karalis
- Department of Internal Medicine III, University Clinic Carl-Gustav-Carus, University of Dresden, Dresden, Germany
- Developmental Biology Section, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
- Division of Endocrinology, Children's Hospital, Boston, MA, USA
| | - S R Bornstein
- Department of Internal Medicine III, University Clinic Carl-Gustav-Carus, University of Dresden, Dresden, Germany
| | - T Chavakis
- Department of Internal Medicine III, Division of Vascular Inflammation, Diabetes and Kidney, University Clinic Carl-Gustav-Carus, University of Dresden, Fetscherstrasse 74, 01307, Dresden, Germany.
- Institute of Physiology, University of Dresden, Dresden, Germany.
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22
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Birerdinc A, Jarrar M, Stotish T, Randhawa M, Baranova A. Manipulating molecular switches in brown adipocytes and their precursors: a therapeutic potential. Prog Lipid Res 2012; 52:51-61. [PMID: 22960032 DOI: 10.1016/j.plipres.2012.08.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Revised: 03/28/2012] [Accepted: 08/11/2012] [Indexed: 01/07/2023]
Abstract
Brown adipocytes constitute a metabolically active tissue responsible for non-shivering thermogenesis and the depletion of excess calories. Differentiation of brown fat adipocytes de novo or stimulation of pre-existing brown adipocytes within white adipose depots could provide a novel method for reducing the obesity and alleviating the consequences of type II diabetes worldwide. In this review, we addressed several molecular mechanisms involved in the control of brown fat activity, namely, the β₃-adrenergic stimulation of thermogenesis during exposure to cold or by catecholamines; the augmentation of thyroid function; the modulation of peroxisome proliferator-activated receptor gamma (PPARγ), transcription factors of the C/EBP family, and the PPARγ co-activator PRDM16; the COX-2-driven expression of UCP1; the stimulation of the vanilloid subfamily receptor TRPV1 by capsaicin and monoacylglycerols; the effects of BMP7 or its analogs; the cannabinoid receptor antagonists and melanogenesis modulating agents. Manipulating one or more of these pathways may provide a solution to the problem of harnessing brown fat's thermogenic potential. However, a better understanding of their interplay and other homeostatic mechanisms is required for the development of novel therapies for millions of obese and/or diabetic individuals.
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Affiliation(s)
- Aybike Birerdinc
- Center for the Study of Chronic Metabolic Diseases, School of Systems Biology, College of Science, George Mason University, Fairfax, VA, USA
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23
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Abstract
Macrophages are key innate immune effector cells best known for their role as professional phagocytes, which also include neutrophils and dendritic cells. Recent evidence indicates that macrophages are also key players in metabolic homoeostasis. Macrophages can be found in many tissues, where they respond to metabolic cues and produce pro- and/or anti-inflammatory mediators to modulate metabolite programmes. Certain metabolites, such as fatty acids, ceramides and cholesterol crystals, elicit inflammatory responses through pathogen-sensing signalling pathways, implicating a maladaptation of macrophages and the innate immune system to elevated metabolic stress associated with overnutrition in modern societies. The outcome of this maladaptation is a feedforward inflammatory response leading to a state of unresolved inflammation and a collection of metabolic pathologies, including insulin resistance, fatty liver, atherosclerosis and dyslipidaemia. The present review summarizes what is known about the contributions of macrophages to metabolic diseases and the signalling pathways that are involved in metabolic stress-induced macrophage activation. Understanding the role of macrophages in these processes will help us to develop therapies against detrimental effects of the metabolic syndrome.
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Townsend K, Tseng YH. Brown adipose tissue: Recent insights into development, metabolic function and therapeutic potential. Adipocyte 2012; 1:13-24. [PMID: 23700507 PMCID: PMC3661118 DOI: 10.4161/adip.18951] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Obesity is currently a global pandemic, and is associated with increased mortality and co-morbidities including many metabolic diseases. Obesity is characterized by an increase in adipose mass due to increased energy intake, decreased energy expenditure, or both. While white adipose tissue is specialized for energy storage, brown adipose tissue has a high concentration of mitochondria and uniquely expresses uncoupling protein 1, enabling it to be specialized for energy expenditure and thermogenesis. Although brown fat was once considered only necessary in babies, recent morphological and imaging studies have provided evidence that, contrary to prior belief, this tissue is present and active in adult humans. In recent years, the topic of brown adipose tissue has been reinvigorated with many new studies regarding brown adipose tissue differentiation, function and therapeutic promise. This review summarizes the recent advances, discusses the emerging questions and offers perspective on the potential therapeutic applications targeting this tissue.
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Affiliation(s)
- Kristy Townsend
- Joslin Diabetes Center and Harvard Medical School; Boston, MA USA
| | - Yu-Hua Tseng
- Joslin Diabetes Center and Harvard Medical School; Boston, MA USA
- Harvard Stem Cell Institute; Harvard University; Cambridge, MA USA
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