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Blondin DP. Human thermogenic adipose tissue. Curr Opin Genet Dev 2023; 80:102054. [PMID: 37269791 DOI: 10.1016/j.gde.2023.102054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 04/11/2023] [Accepted: 04/28/2023] [Indexed: 06/05/2023]
Abstract
Human thermogenic adipose tissue has long been touted as a promising therapeutic target for obesity and its associated metabolic diseases. Here, we provide a brief overview of the current knowledge of in vivo human thermogenic adipose tissue metabolism. We explore the evidence provided by retrospective and prospective studies describing the association of brown adipose tissue (BAT) [18F]fluorodeoxyglucose accumulation and various cardiometabolic risk factors. Although these studies have been invaluable in generating hypothesis, it has also raised some questions about the reliability of this method as an indicator of BAT thermogenic capacity. We discuss the evidence in support of human BAT functioning as a local thermogenic organ and energy sink, as an endocrine organ, and as a biomarker of adipose tissue health.
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Affiliation(s)
- Denis P Blondin
- Division of Neurology, Department of Medicine, Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, 3001, 12th Ave North, Sherbrooke, Quebec J1H 5N4, Canada.
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2
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Martínez-Meza Y, Escobar-Ortiz A, Buergo-Martínez F, Pérez-Ramírez IF, Pérez-Jiménez J, Salgado LM, Reynoso-Camacho R. Three Varieties of Grape Pomace, with Distinctive Extractable:Non-Extractable Polyphenol Ratios, Differentially Reduce Obesity and Its Complications in Rats Fed a High-Fat High-Fructose Diet. Foods 2023; 12:foods12071370. [PMID: 37048194 PMCID: PMC10093191 DOI: 10.3390/foods12071370] [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: 02/17/2023] [Revised: 03/14/2023] [Accepted: 03/16/2023] [Indexed: 04/14/2023] Open
Abstract
Grape pomace is a commonly discarded by-product characterized by high extractable (EPP) and non-extractable (NEPP) polyphenol contents which exhibits anti-obesogenic effects. However, the relevance of each fraction needs to be elucidated. In this work, we examined the effects of three pomaces with different concentrations of EPPs and NEPPs on metabolic alterations associated with obesity. The NEPP:EPP ratio of the grape pomaces was 1.48 for Malbec, 1.10 for Garnacha, and 5.76 for Syrah grape varieties. Rats fed a high-fat high-fructose diet supplemented with Malbec grape pomace (HFFD + MAL) Syrah grape pomace (HFFD + SYR) or Garnacha grape pomace (HFFD + GAR) showed significantly less weight gain: 20%, 15%, and 12% less, respectively, compared to HFFD controls. The adiposity index was also significantly decreased by 20% in the HFFD + MAL and HFFD + SYR groups, and by 13% in the HFFD + GAR group. Serum triglycerides were significantly decreased by 46% in the HFFD + MAL group and by 31% in the HFFD + GAR group, compared to the HFFD group, but not in the HFFD + SYR group. All pomace supplementations regulated postprandial glucose in an oral glucose tolerance test. Therefore, grape pomaces containing both EPPs and NEPPs exert beneficial effects on body weight and glucose homeostasis, while EPPs seem to control triglyceride levels more effectively.
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Affiliation(s)
- Yuridia Martínez-Meza
- Facultad de Química, Universidad Autónoma de Querétaro, Querétaro 76010, Qro., Mexico
| | | | | | | | - Jara Pérez-Jiménez
- Department of Metabolism and Nutrition, Institute of Food Science, Technology and Nutrition (ICTAN-CSIC), José Antonio Novais 10, 28040 Madrid, Spain
- CIBER of Diabetes and Associated Metabolic Disease (CIBERDEM), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Luis M Salgado
- CICATA-Querétaro, Instituto Politécnico Nacional, Querétaro 76010, Qro., Mexico
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3
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Abstract
Brown adipose tissue (BAT) displays the unique capacity to generate heat through uncoupled oxidative phosphorylation that makes it a very attractive therapeutic target for cardiometabolic diseases. Here, we review BAT cellular metabolism, its regulation by the central nervous and endocrine systems and circulating metabolites, the plausible roles of this tissue in human thermoregulation, energy balance, and cardiometabolic disorders, and the current knowledge on its pharmacological stimulation in humans. The current definition and measurement of BAT in human studies relies almost exclusively on BAT glucose uptake from positron emission tomography with 18F-fluorodeoxiglucose, which can be dissociated from BAT thermogenic activity, as for example in insulin-resistant states. The most important energy substrate for BAT thermogenesis is its intracellular fatty acid content mobilized from sympathetic stimulation of intracellular triglyceride lipolysis. This lipolytic BAT response is intertwined with that of white adipose (WAT) and other metabolic tissues, and cannot be independently stimulated with the drugs tested thus far. BAT is an interesting and biologically plausible target that has yet to be fully and selectively activated to increase the body's thermogenic response and shift energy balance. The field of human BAT research is in need of methods able to directly, specifically, and reliably measure BAT thermogenic capacity while also tracking the related thermogenic responses in WAT and other tissues. Until this is achieved, uncertainty will remain about the role played by this fascinating tissue in human cardiometabolic diseases.
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Affiliation(s)
- André C Carpentier
- Correspondence: André C. Carpentier, MD, Division of Endocrinology, Faculty of Medicine, University of Sherbrooke, 3001, 12th Ave N, Sherbrooke, Quebec, J1H 5N4, Canada.
| | - Denis P Blondin
- Division of Neurology, Department of Medicine, Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Quebec, J1H 5N4, Canada
| | | | - Denis Richard
- Centre de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Quebec City, Quebec, G1V 4G5, Canada
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Paul A, Chanclón B, Brännmark C, Wittung-Stafshede P, Olofsson CS, Asterholm IW, Parekh SH. Comparing lipid remodeling of brown adipose tissue, white adipose tissue, and liver after one-week high fat diet intervention with quantitative Raman microscopy. J Cell Biochem 2023; 124:382-395. [PMID: 36715685 DOI: 10.1002/jcb.30372] [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: 09/20/2022] [Revised: 12/20/2022] [Accepted: 01/09/2023] [Indexed: 01/31/2023]
Abstract
Brown adipose tissue (BAT) consists of highly metabolically active adipocytes that catabolize nutrients to produce heat. Playing an active role in triacylglycerol (TAG) clearance, research has shown that dietary fatty acids can modulate the TAG chemistry deposition in BAT after weeks-long dietary intervention, similar to what has been shown in white adipose tissue (WAT). Our objective was to compare the influence of sustained, nonchronic dietary intervention (a 1-week interval) on WAT and interscapular BAT lipid metabolism and deposition in situ. We use quantitative, label-free chemical microscopy to show that 1 week of high fat diet (HFD) intervention results in dramatically larger lipid droplet (LD) growth in BAT (and liver) compared to LD growth in inguinal WAT (IWAT). Moreover, BAT showed lipid remodeling as increased unsaturated TAGs in LDs, resembling the dietary lipid composition, while WAT (and liver) did not show lipid remodeling on this time scale. Concurrently, expression of genes involved in lipid metabolism, particularly desaturases, was reduced in BAT and liver from HFD-fed mice after 1 week. Our data show that BAT lipid chemistry remodels exceptionally fast to dietary lipid intervention compared WAT, which further points towards a role in TAG clearance.
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Affiliation(s)
- Alexandra Paul
- Division of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA
| | - Belén Chanclón
- Department of Physiology (Metabolic Physiology), Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Cecilia Brännmark
- Department of Physiology (Metabolic Physiology), Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Pernilla Wittung-Stafshede
- Division of Chemical Biology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Charlotta S Olofsson
- Department of Physiology (Metabolic Physiology), Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Ingrid Wernstedt Asterholm
- Department of Physiology (Metabolic Physiology), Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Sapun H Parekh
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Mainz, Germany
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Different Protein Sources Enhance 18FDG-PET/MR Uptake of Brown Adipocytes in Male Subjects. Nutrients 2022; 14:nu14163411. [PMID: 36014915 PMCID: PMC9413993 DOI: 10.3390/nu14163411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 08/13/2022] [Accepted: 08/16/2022] [Indexed: 11/17/2022] Open
Abstract
Background: The unique ability of brown adipocytes to increase metabolic rate suggests that they could be targeted as an obesity treatment. Objective: The objective of the study was to search for new dietary factors that may enhance brown adipose tissue (BAT) activity. Methods: The study group comprised 28 healthy non-smoking males, aged 21–42 years old. All volunteers underwent a physical examination and a 75 g oral glucose tolerance test (75g-OGTT). Serum atrial and brain natriuretic peptide (ANP, BNP), PRD1-BF1-RIZ1 homologous domain containing 16 (PRDM16) and eukaryotic translation initiation factor 4E (eIF4E) measurements were taken, and 3-day food intake diaries were completed. Body composition measurements were assessed using dual-energy X-ray absorptiometry (DXA) scanning and bioimpedance methods. An fluorodeoxyglucose-18 (FDG-18) uptake in BAT was assessed by positron emission tomography/magnetic resonance (PET/MR) in all participants after 2 h cold exposure. The results were adjusted for age, daily energy intake, and DXA lean mass. Results: Subjects with detectable BAT (BAT(+)) were characterized by a higher percentage of energy obtained from dietary protein and fat and higher muscle mass (p = 0.01, p = 0.02 and p = 0.04, respectively). In the BAT(+) group, animal protein intake was positively associated (p= 0.04), whereas the plant protein intake negatively correlated with BAT activity (p = 0.03). Additionally, the presence of BAT was inversely associated with BNP concentration in the 2 h of cold exposure (p = 0.002). Conclusion: The outcomes of our study suggest that different macronutrient consumption may be a new way to modulate BAT activity leading to weight reduction.
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Maternal high-fat diet programs white and brown adipose tissue lipidome and transcriptome in offspring in a sex- and tissue-dependent manner in mice. Int J Obes (Lond) 2022; 46:831-842. [PMID: 34997206 PMCID: PMC8960419 DOI: 10.1038/s41366-021-01060-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 12/10/2021] [Accepted: 12/22/2021] [Indexed: 02/06/2023]
Abstract
Objective The prevalence of overweight and obesity among children has drastically increased during the last decades and maternal obesity has been demonstrated as one of the ultimate factors. Nutrition-stimulated transgenerational regulation of key metabolic genes is fundamental to the developmental origins of the metabolic syndrome. Fetal nutrition may differently influence female and male offspring. Methods Mice dam were fed either a control diet or a high-fat diet (HFD) for 6-week prior mating and continued their respective diet during gestation and lactation. At weaning, female and male offspring were fed the HFD until sacrifice. White (WAT) and brown (BAT) adipose tissues were investigated in vivo by nuclear magnetic resonance at two different timepoints in life (midterm and endterm) and tissues were collected at endterm for lipidomic analysis and RNA sequencing. We explored the sex-dependent metabolic adaptation and gene programming changes by maternal HFD in visceral AT (VAT), subcutaneous AT (SAT) and BAT of offspring. Results We show that the triglyceride profile varies between adipose depots, sexes and maternal diet. In female offspring, maternal HFD remodels the triglycerides profile in SAT and BAT, and increases thermogenesis and cell differentiation in BAT, which may prevent metabolic complication later in life. Male offspring exhibit whitening of BAT and hyperplasia in VAT when born from high-fat mothers, with impaired metabolic profile. Maternal HFD differentially programs gene expression in WAT and BAT of female and male offspring. Conclusion Maternal HFD modulates metabolic profile in offspring in a sex-dependent manner. A sex- and maternal diet-dependent gene programming exists in VAT, SAT, and BAT which may be key player in the sexual dimorphism in the metabolic adaptation later in life.
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Monfort-Pires M, Regeni-Silva G, Dadson P, Nogueira GA, U-Din M, Ferreira SRG, Sapienza MT, Virtanen K, Velloso LA. Brown fat triglyceride content is associated with cardiovascular risk markers in adults from a tropical region. Front Endocrinol (Lausanne) 2022; 13:919588. [PMID: 35928901 PMCID: PMC9343995 DOI: 10.3389/fendo.2022.919588] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 06/28/2022] [Indexed: 11/13/2022] Open
Abstract
Brown adipose tissue (BAT) is regarded as an interesting potential target for the treatment of obesity, diabetes, and cardiovascular diseases, and the detailed characterization of its structural and functional phenotype could enable an advance in these fields. Most studies evaluating BAT structure and function were performed in temperate climate regions, and we are yet to know how these findings apply to the 40% of the world's population living in tropical areas. Here, we used 18F-fluorodeoxyglucose positron emission tomography - magnetic resonance imaging to evaluate BAT in 45 lean, overweight, and obese volunteers living in a tropical area in Southeast Brazil. We aimed at investigating the associations between BAT activity, volume, metabolic activity, and BAT content of triglycerides with adiposity and cardiovascular risk markers in a sample of adults living in a tropical area and we showed that BAT glucose uptake is not correlated with leanness; instead, BAT triglyceride content is correlated with visceral adiposity and markers of cardiovascular risk. This study expands knowledge regarding the structure and function of BAT in people living in tropical areas. In addition, we provide evidence that BAT triglyceride content could be an interesting marker of cardiovascular risk.
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Affiliation(s)
- Milena Monfort-Pires
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University ofCampinas (UNICAMP), Campinas, Brazil
- *Correspondence: Milena Monfort-Pires, ; Licio A. Velloso,
| | - Giulianna Regeni-Silva
- Department of Nutrition, School of Public Health -University of São Paulo, São Paulo, Brazil
| | - Prince Dadson
- Turku PET Centre, University of Turku, Turku, Finland
| | - Guilherme A. Nogueira
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University ofCampinas (UNICAMP), Campinas, Brazil
| | - Mueez U-Din
- Turku PET Centre, University of Turku, Turku, Finland
- Turku PET Centre, Turku University Hospital, Turku, Finland
| | - Sandra R. G. Ferreira
- Department of Epidemiology, School of Public Health-University of São Paulo, São Paulo, Brazil
| | - Marcelo Tatit Sapienza
- Division of Nuclear Medicine, Department of Radiology and Oncology, Medical School of University of São Paulo (FMUSP), São Paulo, Finland
| | - Kirsi A. Virtanen
- Turku PET Centre, University of Turku, Turku, Finland
- Turku PET Centre, Turku University Hospital, Turku, Finland
- Clinical Nutrition, Institute of Public Health and Clinical Nutrition, University of Eastern Finland (UEF), Kuopio, Finland
| | - Licio A. Velloso
- Laboratory of Cell Signaling, Obesity and Comorbidities Research Center, State University ofCampinas (UNICAMP), Campinas, Brazil
- *Correspondence: Milena Monfort-Pires, ; Licio A. Velloso,
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Donjuán-Loredo G, Espinosa-Tanguma R, León-Bejarano F, Ramírez-Elías JA, Salgado-Delgado R, González FJ, Guevara E, Ramírez-Elías MG. Raman Spectroscopy for Adipose Tissue Assessment in Rat Models of Obesity and Type 1 Diabetes. APPLIED SPECTROSCOPY 2021; 75:1189-1197. [PMID: 33464156 DOI: 10.1177/0003702821990357] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Adipose tissue presents structural and functional changes in obesity and type 1 diabetes mellitus (T1DM). In obesity, the size and number of adipocytes and adipokine secretion increases. In T1DM, a loss of adipose tissue suggests changes in the metabolic activity of this tissue. A significant challenge is to find alternative noninvasive methods to evaluate molecular changes in adipose tissue related to obesity and T1DM. Recently, Raman spectroscopy and chemometrics techniques have emerged as a tool for biological tissue analysis. In this work, we propose the use of Raman spectroscopy to characterize spectral differences in adipose tissue from different rat groups (control, obese, and T1DM). The Raman spectra were analyzed using direct band analysis, ratiometric analysis, and chemometric methods (principal component analysis (PCA) and support vector machines (SVMs)). We found that the Raman spectra of obese rats showed significant spectral differences compared to control and diabetic groups related to fatty acids Raman bands. Also, the obese group has a significant decrease in the degree of unsaturation of lipids. The PCA-SVM models showed classification performance ranging from 71.43% to 71.79% accuracy for brown and white adipose tissue samples, respectively. In conclusion, the results demonstrate that Raman spectroscopy can be used as a nondestructive method to assess adipose tissue according to a metabolic condition.
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Affiliation(s)
| | | | - Fabiola León-Bejarano
- Facultad de Ciencias, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Jordi A Ramírez-Elías
- Facultad de Ciencias, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | | | - Francisco J González
- Coordinación para la Innovación y Aplicación de la Ciencia y la Tecnología (CIACyT), Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Edgar Guevara
- Coordinación para la Innovación y Aplicación de la Ciencia y la Tecnología (CIACyT), Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
- CONACYT-Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
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Laurila S, Sun L, Lahesmaa M, Schnabl K, Laitinen K, Klén R, Li Y, Balaz M, Wolfrum C, Steiger K, Niemi T, Taittonen M, U-Din M, Välikangas T, Elo LL, Eskola O, Kirjavainen AK, Nummenmaa L, Virtanen KA, Klingenspor M, Nuutila P. Secretin activates brown fat and induces satiation. Nat Metab 2021; 3:798-809. [PMID: 34158656 DOI: 10.1038/s42255-021-00409-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 05/07/2021] [Indexed: 02/06/2023]
Abstract
Brown adipose tissue (BAT) thermogenesis is activated by feeding. Recently, we revealed a secretin-mediated gut-BAT-brain axis, which stimulates satiation in mice, but the purpose of meal-induced BAT activation in humans has been unclear. In this placebo-controlled, randomized crossover study, we investigated the effects of intravenous secretin on BAT metabolism (measured with [18F]FDG and [15O]H2O positron emission tomography) and appetite (measured with functional magnetic resonance imaging) in healthy, normal weight men (GUTBAT trial no. NCT03290846). Participants were blinded to the intervention. Secretin increased BAT glucose uptake (primary endpoint) compared to placebo by 57% (median (interquartile range, IQR), 0.82 (0.77) versus 0.59 (0.53) μmol per 100 g per min, 95% confidence interval (CI) (0.09, 0.89), P = 0.002, effect size r = 0.570), while BAT perfusion remained unchanged (mean (s.d.) 4.73 (1.82) versus 6.14 (3.05) ml per 100 g per min, 95%CI (-2.91, 0.07), P = 0.063, effect size d = -0.549) (n = 15). Whole body energy expenditure increased by 2% (P = 0.011) (n = 15). Secretin attenuated blood-oxygen level-dependent activity (primary endpoint) in brain reward circuits during food cue tasks (significance level false discovery rate corrected at P = 0.05) (n = 14). Caloric intake did not significantly change, but motivation to refeed after a meal was delayed by 39 min (P = 0.039) (n = 14). No adverse effects were detected. Here we show in humans that secretin activates BAT, reduces central responses to appetizing food and delays the motivation to refeed after a meal. This suggests that meal-induced, secretin-mediated BAT activation is relevant in the control of food intake in humans. As obesity is increasing worldwide, this appetite regulating axis offers new possibilities for clinical research in treating obesity.
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Affiliation(s)
- Sanna Laurila
- Turku PET Centre, University of Turku, Turku, Finland
- Heart Center, Turku University Hospital, Turku, Finland
- Satakunta Central Hospital, Pori, Finland
| | - Lihua Sun
- Turku PET Centre, University of Turku, Turku, Finland
| | - Minna Lahesmaa
- Turku PET Centre, University of Turku, Turku, Finland
- Department of Internal Medicine, Jorvi Hospital, Helsinki University Hospital, Helsinki, Finland
| | - Katharina Schnabl
- Chair for Molecular Nutritional Medicine, Technical University of Munich, TUM School of Life Sciences, Freising, Germany
- EKFZ - Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany
- ZIEL - Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Kirsi Laitinen
- Institute of Biomedicine, University of Turku, Turku, Finland
| | - Riku Klén
- Turku PET Centre, University of Turku, Turku, Finland
| | - Yongguo Li
- Chair for Molecular Nutritional Medicine, Technical University of Munich, TUM School of Life Sciences, Freising, Germany
- EKFZ - Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany
- ZIEL - Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Miroslav Balaz
- Institute of Food, Nutrition and Health, ETH Zürich, Schwerzenbach, Switzerland
| | - Christian Wolfrum
- Institute of Food, Nutrition and Health, ETH Zürich, Schwerzenbach, Switzerland
| | - Katja Steiger
- Institue of Pathology, School of Medicine, Technical University of Munich, Munich, Germany
| | - Tarja Niemi
- Department of Plastic and General Surgery, Turku University Hospital, Turku, Finland
| | - Markku Taittonen
- Department of Anesthesiology, Turku University Hospital, Turku, Finland
| | - Mueez U-Din
- Turku PET Centre, University of Turku, Turku, Finland
- Turku PET Centre, Turku University Hospital, Turku, Finland
| | | | - Laura L Elo
- Institute of Biomedicine, University of Turku, Turku, Finland
- Turku Bioscience Centre, University of Turku, Turku, Finland
- Turku Bioscience Centre, Åbo Akademi University, Turku, Finland
| | - Olli Eskola
- Turku PET Centre, University of Turku, Turku, Finland
| | | | - Lauri Nummenmaa
- Turku PET Centre, University of Turku, Turku, Finland
- Department of Psychology, University of Turku, Turku, Finland
| | - Kirsi A Virtanen
- Turku PET Centre, Turku University Hospital, Turku, Finland
- Institute of Public Health and Clinical Nutrition - University of Eastern Finland (UEF), Kuopio, Finland
- Department of Endocrinology and Clinical Nutrition, Kuopio University Hospital, Kuopio, Finland
| | - Martin Klingenspor
- Chair for Molecular Nutritional Medicine, Technical University of Munich, TUM School of Life Sciences, Freising, Germany
- EKFZ - Else Kröner Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, Germany
- ZIEL - Institute for Food & Health, Technical University of Munich, Freising, Germany
| | - Pirjo Nuutila
- Turku PET Centre, University of Turku, Turku, Finland.
- Turku PET Centre, Turku University Hospital, Turku, Finland.
- Department of Endocrinology, Turku University Hospital, Turku, Finland.
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10
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Santhanam P, Rowe SP, Solnes LB, Quainoo B, Ahima RS. A systematic review of imaging studies of human brown adipose tissue. Ann N Y Acad Sci 2021; 1495:5-23. [PMID: 33604891 DOI: 10.1111/nyas.14579] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 01/25/2021] [Accepted: 01/31/2021] [Indexed: 02/06/2023]
Abstract
Brown adipose tissue (BAT) is involved in energy dissipation and has been linked to weight loss, insulin sensitivity, and reduced risk of atherosclerotic disease. BAT is found most often in the supraclavicular region, as well as mediastinal and paravertebral areas, and it is predominantly seen in young persons. BAT is activated by cold temperature and the sympathetic nervous system. In humans, BAT was initially detected via 2-deoxy-2-[18 F]fluoro-d-glucose (FDG) positron emission tomography/computed tomography (PET/CT), a high-resolution molecular imaging modality used to identify and stage malignancies. Recent studies have shown that BAT can be localized using conventional imaging modalities, such as CT or magnetic resonance imaging, as well as radiotracers used for single-photon emission CT. In this systematic review, we have summarized the evidence for BAT detection in humans using various imaging techniques.
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Affiliation(s)
- Prasanna Santhanam
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Asthma and Allergy Center, Baltimore, Maryland
| | - Steven P Rowe
- Division of Nuclear Medicine, Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Lilja B Solnes
- Division of Nuclear Medicine, Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Brittany Quainoo
- Columbian College of Arts and Sciences, George Washington University, Washington, DC
| | - Rexford S Ahima
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Asthma and Allergy Center, Baltimore, Maryland
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11
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Brown Adipose Tissue and Its Role in Insulin and Glucose Homeostasis. Int J Mol Sci 2021; 22:ijms22041530. [PMID: 33546400 PMCID: PMC7913527 DOI: 10.3390/ijms22041530] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/21/2021] [Accepted: 02/01/2021] [Indexed: 12/15/2022] Open
Abstract
The increased worldwide prevalence of obesity, insulin resistance, and their related metabolic complications have prompted the scientific world to search for new possibilities to combat obesity. Brown adipose tissue (BAT), due to its unique protein uncoupling protein 1 (UPC1) in the inner membrane of the mitochondria, has been acknowledged as a promising approach to increase energy expenditure. Activated brown adipocytes dissipate energy, resulting in heat production. In other words, BAT burns fat and increases the metabolic rate, promoting a negative energy balance. Moreover, BAT alleviates metabolic complications like dyslipidemia, impaired insulin secretion, and insulin resistance in type 2 diabetes. The aim of this review is to explore the role of BAT in total energy expenditure, as well as lipid and glucose homeostasis, and to discuss new possible activators of brown adipose tissue in humans to treat obesity and metabolic disorders.
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12
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Lelis DDF, Andrade JMO, Almenara CCP, Broseguini-Filho GB, Mill JG, Baldo MP. High fructose intake and the route towards cardiometabolic diseases. Life Sci 2020; 259:118235. [DOI: 10.1016/j.lfs.2020.118235] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/29/2020] [Accepted: 08/05/2020] [Indexed: 02/06/2023]
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13
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Prevalence and Associated Factor of Brown Adipose Tissue: Systematic Review and Meta-Analysis. BIOMED RESEARCH INTERNATIONAL 2020; 2020:9106976. [PMID: 32685543 PMCID: PMC7317326 DOI: 10.1155/2020/9106976] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 05/08/2020] [Accepted: 06/01/2020] [Indexed: 01/03/2023]
Abstract
Background Brown adipose tissue generates heat instead of storing energy. It is important in the regulation of body weight, and individual variation in adaptive thermogenesis can be attributed to variations in the amount or activity of BAT. Objective The objective of this study was to systematically review different articles to assess the prevalence of BAT and its associated factors and relation with obesity and diabetes mellitus. Methods A systematic review and meta-analysis were employed on published research works from different electronic databases using keywords. Cross-sectional studies and a few experimental studies were included for systematic review, and only studies done on human population were used for quantitative analysis. Twenty-two peer-reviewed papers were included in the systematic review, and eight papers were used for the meta-analysis for estimation of pooled prevalence of brown adipose tissue using selection criteria. Results The pooled prevalence of brown adipose tissue among adults was 6.97% (95% CI: 6.51-7.43), and it was 7.4% (95% CI 6.51-7.43) after sequential omission of a single study. The heterogeneity in estimating the pooled prevalence among the studies was statistically significant (Cochran Q test, P < 0.001, I 2 = 71.2%), and after sequential omission of a single study, it becomes Cochran Q test, P = 0.065, I 2 = 49.4%. The brown adipose tissue activity was significantly lower in overweight or obese subjects than in lean subjects. Conclusion The percentage of adult individuals with brown adipose tissue was high, and its activity was reduced in obese individuals. Although it is reduced in amount, still it presents in obese individuals. So, activation of the brown adipose tissue in adult and older individuals should be a target for the treatment of obesity.
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14
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Gu J, Wang X, Yang H, Li H, Wang J. Preclinical in vivo imaging for brown adipose tissue. Life Sci 2020; 249:117500. [PMID: 32147430 DOI: 10.1016/j.lfs.2020.117500] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 02/23/2020] [Accepted: 03/02/2020] [Indexed: 12/22/2022]
Abstract
Brown adipose tissue (BAT) has multiple functions in the human body, including the production of heat and increasing energy consumption. However, BAT is also related to many kinds of diseases, such as obesity and metabolic disorders. The progression of such diseases occurs at the cellular level, and thus, imaging techniques could prove greatly beneficial for determining optimal therapeutic regimens. Currently, positron-emission tomography (PET) is considered to be the gold standard for assessing the function of activated BAT. However, PET also has inherent disadvantages, and, thus, recent efforts have been focused on exploring, and potentially developing, new imaging techniques to better observe BAT and evaluate its metabolic function. Researchers have already achieved promising success with computed tomography, magnetic resonance approaches, ultrasound, new tracers for use in PET, and other imaging techniques through in vivo and in vitro animal experiments. Since, these studies have shown that BAT may serve as an effective therapeutic target for treatment of metabolic dysfunction diseases, the development of an efficient in vivo BAT imaging technique that is applicable to humans will prove to be of great clinical value. In this review, classical PET imaging technique is highlighted as well as the current status of preclinical imaging methods developed for BAT examination.
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Affiliation(s)
- Jiaojiao Gu
- Department of Ultrasound, Shengjing Hospital of China Medical University, Shengjing Hospital, No. 36, Sanhao Street, Heping District, Shenyang, Liaoning, China
| | - Xinlu Wang
- Department of Ultrasound, Shengjing Hospital of China Medical University, Shengjing Hospital, No. 36, Sanhao Street, Heping District, Shenyang, Liaoning, China.
| | - Hua Yang
- Department of Ultrasound, Shengjing Hospital of China Medical University, Shengjing Hospital, No. 36, Sanhao Street, Heping District, Shenyang, Liaoning, China
| | - He Li
- Department of Ultrasound, Shengjing Hospital of China Medical University, Shengjing Hospital, No. 36, Sanhao Street, Heping District, Shenyang, Liaoning, China
| | - Jie Wang
- Department of Ultrasound, Shengjing Hospital of China Medical University, Shengjing Hospital, No. 36, Sanhao Street, Heping District, Shenyang, Liaoning, China
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15
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Raiko J, Orava J, Savisto N, Virtanen KA. High Brown Fat Activity Correlates With Cardiovascular Risk Factor Levels Cross-Sectionally and Subclinical Atherosclerosis at 5-Year Follow-Up. Arterioscler Thromb Vasc Biol 2020; 40:1289-1295. [PMID: 31941384 DOI: 10.1161/atvbaha.119.313806] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Brown adipose tissue (BAT) activity correlates negatively with obesity and insulin resistance, and BAT has been suggested to act as a protective factor against atherogenesis. We aimed to examine subclinical atherosclerosis and risk factor levels in a group of individuals who had 5 years earlier participated in positron-emission tomography studies with measurements of BAT activity. Approach and Results: Study cohort (males/females=5/26, baseline age 41.4±7.9 years; body mass index, 26.8±6.3 kg/m2) underwent positron-emission tomography imaging at baseline with [18F] FDG (glucose uptake) and [15O] H2O (perfusion) to measure BAT activity during cold exposure. At 5-year follow-up, ultrasound was performed to measure carotid intima-media thickness, carotid distensibility (a marker of arterial elasticity), and brachial flow-mediated dilation (an estimate of endothelial function). Fasting plasma lipids and hemoglobin A1c were measured from venous samples at baseline and at follow-up. Median values were used as cut points for high cold-induced BAT activity (BAT glucose uptake >2.40 μmoL/100 g per minute and perfusion >8.4 mL/100 g per minute). Baseline cold-induced BAT glucose uptake and perfusion correlated directly with carotid distensibility and inversely with mean bulbus intima-media thickness and maximum intima-media thickness (P always ≤0.02). Baseline body mass index, plasma triglycerides, and HbA1c correlated negatively with BAT glucose uptake and perfusion in cold (P always ≤0.048). Correlations between cold-induced BAT activity, cardiovascular risk factors, and atherosclerosis were attenuated with corrections for multiple comparisons. CONCLUSIONS Cold-induced BAT activity at baseline seems to correlate with lower levels of conventional cardiovascular risk factors at baseline and with lower carotid intima-media thickness and higher carotid elasticity at 5-year follow-up.
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Affiliation(s)
- Juho Raiko
- From the Turku PET Centre, Turku University Hospital, Finland (J.R., J.O., K.A.V.)
| | - Janne Orava
- From the Turku PET Centre, Turku University Hospital, Finland (J.R., J.O., K.A.V.)
| | - Nina Savisto
- Turku PET Centre, University of Turku, Finland (N.S.)
| | - Kirsi A Virtanen
- From the Turku PET Centre, Turku University Hospital, Finland (J.R., J.O., K.A.V.)
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16
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McNeill BT, Morton NM, Stimson RH. Substrate Utilization by Brown Adipose Tissue: What's Hot and What's Not? Front Endocrinol (Lausanne) 2020; 11:571659. [PMID: 33101206 PMCID: PMC7545119 DOI: 10.3389/fendo.2020.571659] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 09/14/2020] [Indexed: 12/20/2022] Open
Abstract
Our understanding of brown adipose tissue (BAT) function in humans has increased rapidly over the past 10 years. This is predominantly due to the development of powerful non-invasive imaging techniques such as positron emission tomography that can quantify BAT mass and function using metabolic tracers. Activation of BAT during cold-induced thermogenesis is an effective way to dissipate energy to generate heat and requires utilization of multiple energy substrates for optimal function. This has led to interest in the activation of BAT as a potential therapeutic target for type 2 diabetes, dyslipidaemia, and obesity. Here, we provide an overview of the current understanding of BAT substrate utilization in humans and highlight additional mechanisms found in rodents, where BAT more prominently contributes to energy expenditure. During thermogenesis, BAT demonstrates substantially increased glucose uptake which appears to be critical for BAT function. However, glucose is not fully oxidized, with a large proportion converted to lactate. The primary energy substrate for thermogenesis is fatty acids, released from brown adipocyte triglyceride stores. Active BAT also sequesters circulating lipids to sustain optimal thermogenesis. Recent evidence reveals that metabolic intermediates from the tricarboxylic acid cycle and glycolytic pathways also play a critical role in BAT function. Understanding the role of these metabolites in regulating thermogenesis and whole body substrate utilization may elucidate novel strategies for therapeutic BAT activation.
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17
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Sun L, Verma S, Michael N, Chan SP, Yan J, Sadananthan SA, Camps SG, Goh HJ, Govindharajulu P, Totman J, Townsend D, Goh JPN, Sun L, Boehm BO, Lim SC, Sze SK, Henry CJ, Hu HH, Velan SS, Leow MKS. Brown Adipose Tissue: Multimodality Evaluation by PET, MRI, Infrared Thermography, and Whole-Body Calorimetry (TACTICAL-II). Obesity (Silver Spring) 2019; 27:1434-1442. [PMID: 31301122 PMCID: PMC6899540 DOI: 10.1002/oby.22560] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/17/2019] [Indexed: 12/11/2022]
Abstract
OBJECTIVE This study aimed to compare the associations of positron emission tomography (PET), magnetic resonance (MR), and infrared thermography (IRT) imaging modalities with energy expenditure (EE) after brown adipose tissue (BAT) activation using capsinoid ingestion and cold exposure. METHODS Twenty participants underwent PET-MR, IRT imaging, and whole-body calorimetry after capsinoid ingestion and cold exposure. Standardized uptake values (SUV) and the fat fraction (FF) of the supraclavicular brown adipose tissue regions were estimated. The anterior supraclavicular temperature (Tscv) from IRT at baseline and postintervention was measured. Two-hour post-capsinoid ingestion EE and post-cold exposure EE served as a reference to correlate fluorodeoxyglucose uptake, FF, and Tscv for BAT assessment. IRT images were geometrically transformed to overlay on PET-MR for visualization of the hottest regions. RESULTS The supraclavicular hot spot identified on IRT closely corresponded to the area of maximal fluorodeoxyglucose uptake on PET images. Controlling for body weight, post-cold exposure Tscv was a significant variable associated with EE (P = 0.025). The SUV was significantly inversely correlated with FF (P = 0.012) and significantly correlated with peak of Tscv during cold exposure in BAT-positive participants (P = 0.022). CONCLUSIONS Tscv correlated positively with EE and was also significantly correlated with SUV after cold exposure. Both IRT and MR FF are promising methods to study BAT activity noninvasively.
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Affiliation(s)
- Lijuan Sun
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology, and Research, National University Health System, Singapore
| | - Sanjay Verma
- Laboratory of Molecular Imaging, Singapore Bioimaging Consortium, Agency for Science, Technology, and Research, Singapore
| | - Navin Michael
- Singapore Institute of Clinical Sciences, Agency for Science, Technology, and Research, Singapore
| | - Siew Pang Chan
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- Cardiovascular Research Institute, National University Heart Centre, Singapore
- College of Science, Health, and Engineering, La Trobe University, Melbourne, Australia
| | - Jianhua Yan
- Molecular Imaging Precision Medicine Collaborative Innovation Center, Shanxi Medical University, Taiyuan, China
| | - Suresh Anand Sadananthan
- Singapore Institute of Clinical Sciences, Agency for Science, Technology, and Research, Singapore
| | - Stefan G Camps
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology, and Research, National University Health System, Singapore
| | - Hui Jen Goh
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology, and Research, National University Health System, Singapore
| | - Priya Govindharajulu
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology, and Research, National University Health System, Singapore
| | - John Totman
- Clinical Imaging Research Centre, Agency for Science, Technology, and Research, National University of Singapore, Singapore
| | - David Townsend
- Clinical Imaging Research Centre, Agency for Science, Technology, and Research, National University of Singapore, Singapore
| | | | - Lei Sun
- Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore Medical School, Singapore
| | - Bernhard Otto Boehm
- Genome Institute of Singapore, Agency for Science, Technology, and Research, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
- Department of Endocrinology, Tan Tock Seng Hospital, Singapore
- Imperial College London, London, UK
| | - Su Chi Lim
- Department of Medicine, Khoo Teck Puat Hospital, Singapore
| | - Siew Kwan Sze
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Christiani Jeyakumar Henry
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology, and Research, National University Health System, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Houchun Harry Hu
- Department of Radiology, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - S Sendhil Velan
- Laboratory of Molecular Imaging, Singapore Bioimaging Consortium, Agency for Science, Technology, and Research, Singapore
- Singapore Institute of Clinical Sciences, Agency for Science, Technology, and Research, Singapore
- Department of Physiology, National University of Singapore, Singapore
- Department of Medicine, National University of Singapore, Singapore
| | - Melvin Khee-Shing Leow
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology, and Research, National University Health System, Singapore
- Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore Medical School, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
- Department of Endocrinology, Tan Tock Seng Hospital, Singapore
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18
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Contribution of brown adipose tissue to human energy metabolism. Mol Aspects Med 2019; 68:82-89. [PMID: 31306668 DOI: 10.1016/j.mam.2019.07.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 07/09/2019] [Accepted: 07/11/2019] [Indexed: 12/24/2022]
Abstract
The present "obesogenic' environment has favored excessive energy intake resulting in the current obesity epidemic and its associated diseases. The epidemic has incentivized scientists to develop novel behavioral and pharmacological strategies that enhance energy expenditure to compensate for excessive energy intake. Although physical activity is effective to increase total energy expenditure, it is insufficient to induce negative energy balance and weight loss. With the discovery of brown adipose tissue (BAT) in adult humans, BAT activation soon emerged as a potential strategy for elevating energy expenditure. BAT is the only tissue that expresses uncoupling protein 1, conferring on this tissue high thermogenic capacity due to a low efficiency for mitochondrial ATP generation. Potential manipulation of BAT mass and activity has fueled the interest in altering whole-body energy balance through increased energy expenditure. Remarkable advances have been made in quantifying the amount and activity of BAT in humans. Many studies have concluded that the amount of active BAT appears insufficient to induce meaningful increases in energy expenditure. Thus, the majority of studies report that BAT activation does not influence body weight and metabolic control in humans. Strategies to increase BAT mass and/or to potentiate BAT activity seem necessary.
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19
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Klepac K, Georgiadi A, Tschöp M, Herzig S. The role of brown and beige adipose tissue in glycaemic control. Mol Aspects Med 2019; 68:90-100. [PMID: 31283940 DOI: 10.1016/j.mam.2019.07.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 07/03/2019] [Accepted: 07/04/2019] [Indexed: 12/15/2022]
Abstract
For the past decade, brown adipose tissue (BAT) has been extensively studied as a potential therapy for obesity and metabolic diseases due to its thermogenic and glucose-consuming properties. It is now clear that the function of BAT goes beyond heat production, as it also plays an important endocrine role by secreting the so-called batokines to communicate with other metabolic tissues and regulate systemic energy homeostasis. However, despite numerous studies showing the benefits of BAT in rodents, it is still not clear whether recruitment of BAT can be utilized to treat human patients. Here, we review the advances on understanding the role of BAT in metabolism and its benefits on glucose and lipid homeostasis in both humans and rodents. Moreover, we discuss the latest methodological approaches to assess the contribution of BAT to human metabolism as well as the possibility to target BAT, pharmacologically or by lifestyle adaptations, to treat metabolic disorders.
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Affiliation(s)
- Katarina Klepac
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Heidelberg University Hospital, Inner Medicine 1, Heidelberg, Germany; Deutsches Zentrum für Diabetesforschung, Neuherberg, Germany
| | - Anastasia Georgiadi
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Heidelberg University Hospital, Inner Medicine 1, Heidelberg, Germany; Deutsches Zentrum für Diabetesforschung, Neuherberg, Germany
| | - Matthias Tschöp
- Deutsches Zentrum für Diabetesforschung, Neuherberg, Germany
| | - Stephan Herzig
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Heidelberg University Hospital, Inner Medicine 1, Heidelberg, Germany; Deutsches Zentrum für Diabetesforschung, Neuherberg, Germany; Chair Molecular Metabolic Control, Technical University Munich, Germany.
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20
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Zhang Y, Hu X, Hu S, Scotti A, Cai K, Wang J, Zhou X, Yang D, Figini M, Pan L, Shangguan J, Yang J, Zhang Z. Non-invasive Imaging Methods for Brown Adipose Tissue Detection and Function Evaluation. ACTA ACUST UNITED AC 2019; 8. [PMID: 31080698 PMCID: PMC6508884 DOI: 10.4172/2165-8048.1000299] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Brown Adipose Tissue (BAT) has a major role in thermoregulation, producing heat by non-shivering thermogenesis. Primarily found in animals and human infants, the presence of significant brown adipose tissue was identified only recently, and its metabolic role in adults was reconsidered. BAT is believed to have an important role in many metabolic diseases, such as obesity and diabetes, and also to be associated with cancer cachexia. Therefore, it is currently a topic of great interest in the research community, and many groups are investigating the mechanisms underlying BAT metabolism in normal and pathological conditions. However, well established non-invasive methods for assessing BAT distribution and function are still lacking. The purpose of this review is to summarize the current state of the art of these methods, with a particular focus on PET, CT and MRI.
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Affiliation(s)
- Yaqi Zhang
- Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Xiaofei Hu
- Department of Radiology, Third Military Medical University Southwest Hospital, Chongqing, China
| | - Su Hu
- Department of Radiology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.,Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Alessandro Scotti
- Department of Radiology, University of Illinois at Chicago, Chicago, IL, USA.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Kejia Cai
- Department of Radiology, University of Illinois at Chicago, Chicago, IL, USA.,Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Jian Wang
- Department of Radiology, Third Military Medical University Southwest Hospital, Chongqing, China
| | - Xin Zhou
- Department of Cardiology, Pingjin Hospital, Tianjin, China
| | - Ding Yang
- Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - Matteo Figini
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Liang Pan
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Department of Radiology, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu, China
| | - Junjie Shangguan
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Jia Yang
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Zhuoli Zhang
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.,Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL, USA
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21
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Karampinos DC, Weidlich D, Wu M, Hu HH, Franz D. Techniques and Applications of Magnetic Resonance Imaging for Studying Brown Adipose Tissue Morphometry and Function. Handb Exp Pharmacol 2019; 251:299-324. [PMID: 30099625 DOI: 10.1007/164_2018_158] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The present review reports on the current knowledge and recent findings in magnetic resonance imaging (MRI) and spectroscopy (MRS) of brown adipose tissue (BAT). The work summarizes the features and mechanisms that allow MRI to differentiate BAT from white adipose tissue (WAT) by making use of their distinct morphological appearance and the functional characteristics of BAT. MR is a versatile imaging modality with multiple contrast mechanisms as potential candidates in the study of BAT, targeting properties of 1H, 13C, or 129Xe nuclei. Techniques for assessing BAT morphometry based on fat fraction and markers of BAT microstructure, including intermolecular quantum coherence and diffusion imaging, are first described. Techniques for assessing BAT function based on the measurement of BAT metabolic activity, perfusion, oxygenation, and temperature are then presented. The application of the above methods in studies of BAT in animals and humans is described, and future directions in MR study of BAT are finally discussed.
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Affiliation(s)
- Dimitrios C Karampinos
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
| | - Dominik Weidlich
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Mingming Wu
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Houchun H Hu
- Department of Radiology, Nationwide Children's Hospital, Columbus, OH, USA
| | - Daniela Franz
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
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22
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Sarasniemi JT, Koskensalo K, Raiko J, Nuutila P, Saunavaara J, Parkkola R, Virtanen KA. Skin temperature may not yield human brown adipose tissue activity in diverse populations. Acta Physiol (Oxf) 2018; 224:e13095. [PMID: 29757496 DOI: 10.1111/apha.13095] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- J. T. Sarasniemi
- Turku PET Centre; University of Turku; Turku Finland
- Turku PET Centre; Turku University Hospital; Turku Finland
| | - K. Koskensalo
- Turku PET Centre; University of Turku; Turku Finland
- Turku PET Centre; Turku University Hospital; Turku Finland
| | - J. Raiko
- Turku PET Centre; University of Turku; Turku Finland
- Turku PET Centre; Turku University Hospital; Turku Finland
| | - P. Nuutila
- Turku PET Centre; University of Turku; Turku Finland
- Turku PET Centre; Turku University Hospital; Turku Finland
| | - J. Saunavaara
- Department of Medical Physics; Turku University Hospital; Turku Finland
| | - R. Parkkola
- Medical Imaging Centre of Southwest Finland; Turku University Hospital; Turku Finland
- Department of Radiology; Turku University Hospital; Turku Finland
- Department of Radiology; University of Turku; Turku Finland
| | - K. A. Virtanen
- Turku PET Centre; University of Turku; Turku Finland
- Turku PET Centre; Turku University Hospital; Turku Finland
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23
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Virtanen KA. Activation of Human Brown Adipose Tissue (BAT): Focus on Nutrition and Eating. Handb Exp Pharmacol 2018; 251:349-357. [PMID: 30141098 DOI: 10.1007/164_2018_136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Brown adipose tissue activation occurs most effectively by cold exposure. In the modern world, we do not spend long periods in cold environment, and eating and meals may be other activators of brown fat function. Short-term regulation of brown fat functional activity by eating involves most importantly insulin. Insulin is capable to increase glucose uptake in human brown adipose tissue fivefold to fasting conditions. Oxidative metabolism in brown fat is doubled both by cold and by a meal. Human brown adipose tissue is an insulin-sensitive tissue type, and insulin resistance impairs the function, as is found in obesity. Body weight reduction improves cold-induced activation of human brown adipose tissue.
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Affiliation(s)
- Kirsi A Virtanen
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland. .,Clinical Nutrition, Institute of Public Health and Clinical Nutrition, University of Eastern Finland (UEF), Kuopio, Finland.
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24
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Carpentier AC, Blondin DP, Virtanen KA, Richard D, Haman F, Turcotte ÉE. Brown Adipose Tissue Energy Metabolism in Humans. Front Endocrinol (Lausanne) 2018; 9:447. [PMID: 30131768 PMCID: PMC6090055 DOI: 10.3389/fendo.2018.00447] [Citation(s) in RCA: 197] [Impact Index Per Article: 32.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 07/20/2018] [Indexed: 12/16/2022] Open
Abstract
The demonstration of metabolically active brown adipose tissue (BAT) in humans primarily using positron emission tomography coupled to computed tomography (PET/CT) with the glucose tracer 18-fluorodeoxyglucose (18FDG) has renewed the interest of the scientific and medical community in the possible role of BAT as a target for the prevention and treatment of obesity and type 2 diabetes (T2D). Here, we offer a comprehensive review of BAT energy metabolism in humans. Considerable advances in methods to measure BAT energy metabolism, including nonesterified fatty acids (NEFA), chylomicron-triglycerides (TG), oxygen, Krebs cycle rate, and intracellular TG have led to very good quantification of energy substrate metabolism per volume of active BAT in vivo. These studies have also shown that intracellular TG are likely the primary energy source of BAT upon activation by cold. Current estimates of BAT's contribution to energy expenditure range at the lower end of what would be potentially clinically relevant if chronically sustained. Yet, 18FDG PET/CT remains the gold-standard defining method to quantify total BAT volume of activity, used to calculate BAT's total energy expenditure. Unfortunately, BAT glucose metabolism better reflects BAT's insulin sensitivity and blood flow. It is now clear that most glucose taken up by BAT does not fuel mitochondrial oxidative metabolism and that BAT glucose uptake can therefore be disconnected from thermogenesis. Furthermore, BAT thermogenesis is efficiently recruited upon repeated cold exposure, doubling to tripling its total oxidative capacity, with reciprocal reduction of muscle thermogenesis. Recent data suggest that total BAT volume may be much larger than the typically observed 50-150 ml with 18FDG PET/CT. Therefore, the current estimates of total BAT thermogenesis, largely relying on total BAT volume using 18FDG PET/CT, may underestimate the true contribution of BAT to total energy expenditure. Quantification of the contribution of BAT to energy expenditure begs for the development of more integrated whole body in vivo methods.
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Affiliation(s)
- André C. Carpentier
- Division of Endocrinology, Department of Medicine, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, QC, Canada
| | | | - Kirsi A. Virtanen
- Turku PET Centre, Turku University Hospital, Turku, Finland
- Institute of Public Health and Clinical Nutrition, University of Eastern Finland (UEF), Kuopio, Finland
| | - Denis Richard
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Quebec City, QC, Canada
| | - François Haman
- Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada
| | - Éric E. Turcotte
- Department of Nuclear Medicine and Radiobiology, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, QC, Canada
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Weir G, Ramage LE, Akyol M, Rhodes JK, Kyle CJ, Fletcher AM, Craven TH, Wakelin SJ, Drake AJ, Gregoriades ML, Ashton C, Weir N, van Beek EJR, Karpe F, Walker BR, Stimson RH. Substantial Metabolic Activity of Human Brown Adipose Tissue during Warm Conditions and Cold-Induced Lipolysis of Local Triglycerides. Cell Metab 2018; 27:1348-1355.e4. [PMID: 29805098 PMCID: PMC5988566 DOI: 10.1016/j.cmet.2018.04.020] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Revised: 11/01/2017] [Accepted: 04/27/2018] [Indexed: 12/01/2022]
Abstract
Current understanding of in vivo human brown adipose tissue (BAT) physiology is limited by a reliance on positron emission tomography (PET)/computed tomography (CT) scanning, which has measured exogenous glucose and fatty acid uptake but not quantified endogenous substrate utilization by BAT. Six lean, healthy men underwent 18fluorodeoxyglucose-PET/CT scanning to localize BAT so microdialysis catheters could be inserted in supraclavicular BAT under CT guidance and in abdominal subcutaneous white adipose tissue (WAT). Arterial and dialysate samples were collected during warm (∼25°C) and cold exposure (∼17°C), and blood flow was measured by 133xenon washout. During warm conditions, there was increased glucose uptake and lactate release and decreased glycerol release by BAT compared with WAT. Cold exposure increased blood flow, glycerol release, and glucose and glutamate uptake only by BAT. This novel use of microdialysis reveals that human BAT is metabolically active during warm conditions. BAT activation substantially increases local lipolysis but also utilization of other substrates such as glutamate.
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Affiliation(s)
- Graeme Weir
- Department of Radiology, Royal Infirmary of Edinburgh, Edinburgh, Scotland, UK
| | - Lynne E Ramage
- BHF/University Centre for Cardiovascular Science, University of Edinburgh, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, Scotland, UK
| | - Murat Akyol
- Department of Surgery, Royal Infirmary of Edinburgh, Edinburgh, Scotland, UK
| | - Jonathan K Rhodes
- Department of Anaesthesia and Critical Care, University of Edinburgh, Edinburgh, Scotland, UK
| | - Catriona J Kyle
- BHF/University Centre for Cardiovascular Science, University of Edinburgh, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, Scotland, UK
| | - Alison M Fletcher
- Edinburgh Imaging Facility QMRI, University of Edinburgh, Edinburgh, Scotland, UK
| | - Thomas H Craven
- Department of Anaesthesia and Critical Care, University of Edinburgh, Edinburgh, Scotland, UK
| | - Sonia J Wakelin
- Department of Surgery, Royal Infirmary of Edinburgh, Edinburgh, Scotland, UK
| | - Amanda J Drake
- BHF/University Centre for Cardiovascular Science, University of Edinburgh, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, Scotland, UK
| | | | - Ceri Ashton
- Department of Medical Physics, Royal Infirmary of Edinburgh, Edinburgh, Scotland, UK
| | - Nick Weir
- Edinburgh Imaging Facility QMRI, University of Edinburgh, Edinburgh, Scotland, UK; Department of Medical Physics, Royal Infirmary of Edinburgh, Edinburgh, Scotland, UK
| | - Edwin J R van Beek
- BHF/University Centre for Cardiovascular Science, University of Edinburgh, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, Scotland, UK; Department of Radiology, Royal Infirmary of Edinburgh, Edinburgh, Scotland, UK; Edinburgh Imaging Facility QMRI, University of Edinburgh, Edinburgh, Scotland, UK
| | - Fredrik Karpe
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK; NIHR Oxford Biomedical Research Centre, OUH Trust, Oxford, UK
| | - Brian R Walker
- BHF/University Centre for Cardiovascular Science, University of Edinburgh, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, Scotland, UK; Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Roland H Stimson
- BHF/University Centre for Cardiovascular Science, University of Edinburgh, The Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh EH16 4TJ, Scotland, UK.
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Recent advances in the detection of brown adipose tissue in adult humans: a review. Clin Sci (Lond) 2018; 132:1039-1054. [PMID: 29802209 DOI: 10.1042/cs20170276] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 03/23/2018] [Accepted: 03/23/2018] [Indexed: 02/07/2023]
Abstract
The activation of brown adipose tissue (BAT) is associated with reductions in circulating lipids and glucose in rodents and contributes to energy expenditure in humans indicating the potential therapeutic importance of targetting this tissue for the treatment of a variety of metabolic disorders. In order to evaluate the therapeutic potential of human BAT, a variety of methodologies for assessing the volume and metabolic activity of BAT are utilized. Cold exposure is often utilized to increase BAT activity but inconsistencies in the characteristics of the exposure protocols make it challenging to compare findings. The metabolic activity of BAT in response to cold exposure has most commonly been measured by static positron emission tomography of 18F-fluorodeoxyglucose in combination with computed tomography (18F-FDG PET-CT) imaging, but recent studies suggest that under some conditions this may not always reflect BAT thermogenic activity. Therefore, recent studies have used alternative positron emission tomography and computed tomography (PET-CT) imaging strategies and radiotracers that may offer important insights. In addition to PET-CT, there are numerous emerging techniques that may have utility for assessing BAT metabolic activity including magnetic resonance imaging (MRI), skin temperature measurements, near-infrared spectroscopy (NIRS) and contrast ultrasound (CU). In this review, we discuss and critically evaluate the various methodologies used to measure BAT metabolic activity in humans and provide a contemporary assessment of protocols which may be useful in interpreting research findings and guiding the development of future studies.
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Dadson P, Hannukainen JC, Din MU, Lahesmaa M, Kalliokoski KK, Iozzo P, Pihlajamäki J, Karlsson HK, Parkkola R, Salminen P, Virtanen KA, Nuutila P. Brown adipose tissue lipid metabolism in morbid obesity: Effect of bariatric surgery-induced weight loss. Diabetes Obes Metab 2018; 20:1280-1288. [PMID: 29377423 DOI: 10.1111/dom.13233] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 01/13/2018] [Accepted: 01/22/2018] [Indexed: 02/02/2023]
Abstract
OBJECTIVE We aimed to investigate the effect of bariatric surgery on lipid metabolism in supraclavicular brown adipose tissue in morbidly obese women. We hypothesized that lipid metabolism improves after surgery-induced weight loss. MATERIALS AND METHODS A total of 23 morbidly obese women (BMI, 42.1 ± 4.2 kg/m2 ; age, 43.8 ± 9.8 years) were assessed before and 6 months after bariatric surgery and 15 age- and sex-matched controls (22.6 ± 2.8 kg/m2 ) were assessed once. In the supraclavicular fat depot, fractional (FUR) and NEFA uptake rates were measured with 18 F-FTHA-PET. We assessed tissue morphology (triglyceride content) using computed tomography (CT)-radiodensity (in Hounsfield Units[HU]) and the proportion of fat with high density (sBAT [%]) in the entire supraclavicular fat depot. RESULTS The supraclavicular fractional uptake rate was lower in obese women compared to controls (0.0055 ± 0.0035 vs 0.0161 ± 0.0177 1/min, P = .001). Both FUR (to 0.0074 ± 0.0035 1/min, P = .01) and NEFA uptake rates (to 0.50 ± 0.50 μmol/100 g/min, P = .001) increased after surgery. Compared to controls, obese women had lower CT-radiodensity (-101.2 ± 10.1 vs -82.5 ± 5.8 HU, P < .001) and sBAT (43.4 ± 8.4% vs 64.5 ± 12.4%, P < .001). After surgery, CT-radiodensity increased (to -82.5 ± 9.6 HU, P < .001), signifying decreased triglyceride content and sBAT improved (to 58.0 ± 10.7%, P < .001), indicating an increased proportion of brown fat. The change in tissue morphology, reflected as increase in CT-radiodensity and sBAT (%), was associated with a decrease in adiposity indices and an increase in whole-body insulin sensitivity. CONCLUSIONS A decrease in triglyceride content, coupled with the increased proportion of brown adipose tissue in the supraclavicular fat depot, may play a role in the improvement of whole-body insulin sensitivity observed in morbidly obese women after surgery-induced weight loss.
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Affiliation(s)
- Prince Dadson
- Turku PET Centre, University of Turku, Turku, Finland
| | | | - Mueez U Din
- Turku PET Centre, University of Turku, Turku, Finland
- Turku PET Centre, Turku University Hospital, Turku, Finland
| | - Minna Lahesmaa
- Turku PET Centre, University of Turku, Turku, Finland
- Turku PET Centre, Turku University Hospital, Turku, Finland
| | | | | | - Jussi Pihlajamäki
- Institute of Public Health and Clinical Nutrition, Department of Clinical Nutrition and Obesity Center, Kuopio University Hospital, Kuopio, Finland
| | | | - Riitta Parkkola
- Department of Radiology, Medical Imaging Center, Turku University Hospital, University of Turku and Turku University Hospital, Turku, Finland
| | - Paulina Salminen
- Division of Digestive Surgery and Urology, Department of Acute and Digestive Surgery, Turku University Hospital, Turku, Finland
| | - Kirsi A Virtanen
- Turku PET Centre, University of Turku, Turku, Finland
- Turku PET Centre, Turku University Hospital, Turku, Finland
| | - Pirjo Nuutila
- Turku PET Centre, University of Turku, Turku, Finland
- CNR Institute of Clinical Physiology, Pisa, Italy
- Department of Endocrinology, Turku University Hospital, Turku, Finland
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Franz D, Weidlich D, Freitag F, Holzapfel C, Drabsch T, Baum T, Eggers H, Witte A, Rummeny EJ, Hauner H, Karampinos DC. Association of proton density fat fraction in adipose tissue with imaging-based and anthropometric obesity markers in adults. Int J Obes (Lond) 2017; 42:175-182. [PMID: 28894290 PMCID: PMC5737837 DOI: 10.1038/ijo.2017.194] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 06/30/2017] [Accepted: 08/02/2017] [Indexed: 12/31/2022]
Abstract
Background/Objectives: The purpose of this study was to examine the relationship of the proton density fat fraction (PDFF), measured by magnetic resonance imaging (MRI), of supraclavicular and gluteal adipose tissue with subcutaneous and visceral adipose tissue (SAT and VAT) volumes, liver fat fraction and anthropometric obesity markers. The supraclavicular fossa was selected as a typical location where brown adipocytes may be present in humans and the gluteal region was selected as a typical location enclosing primarily white adipocytes. Subjects/Methods: In this cross-sectional study, 61 adults (44 women, median age 29.3 years, range 21–68 years) underwent an MRI examination of the neck and the abdomen/pelvis (3T, Ingenia, Philips Healthcare). PDFF maps of the supraclavicular and gluteal adipose tissue and the liver were generated. Volumes of SAT and VAT were calculated and supraclavicular and subcutaneous fat were segmented using custom-built post-processing algorithms. Body mass index (BMI), waist circumference and waist-to-height ratio were recorded. Statistical analysis was conducted using the Student's t-test and Pearson correlation analysis. Results: Mean supraclavicular PDFF was 75.3±4.7% (range 65.4–83.8%) and mean gluteal PDFF was 89.7±2.9% (range 82.2-94%), resulting in a significant difference (P<0.0001). Supraclavicular PDFF was positively correlated with VAT (r=0.76, P<0.0001), SAT (r=0.73, P<0.0001), liver PDFF (r=0.42, P=0.0008) and all measured anthropometric obesity markers. Gluteal subcutaneous PDFF also correlated with VAT (r=0.59, P<0.0001), SAT (r=0.63, P<0.0001), liver PDFF (r=0.3, P=0.02) and anthropometric obesity markers. Conclusions: The positive correlations between adipose tissue PDFF and imaging, as well as anthropometric obesity markers suggest that adipose tissue PDFF may be useful as a biomarker for improving the characterization of the obese phenotype, for risk stratification and for selection of appropriate treatment strategies.
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Affiliation(s)
- D Franz
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - D Weidlich
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - F Freitag
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - C Holzapfel
- Institute for Nutritional Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - T Drabsch
- Institute for Nutritional Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - T Baum
- Department of Diagnostic and Interventional Neuroradiology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - H Eggers
- Philips Research Laboratory, Hamburg, Germany
| | - A Witte
- FOM University of Applied Sciences, Essen, Germany
| | - E J Rummeny
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - H Hauner
- Institute for Nutritional Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - D C Karampinos
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
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U Din M, Raiko J, Saari T, Saunavaara V, Kudomi N, Solin O, Parkkola R, Nuutila P, Virtanen KA. Human Brown Fat Radiodensity Indicates Underlying Tissue Composition and Systemic Metabolic Health. J Clin Endocrinol Metab 2017; 102:2258-2267. [PMID: 28368474 DOI: 10.1210/jc.2016-2698] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 03/21/2017] [Indexed: 02/03/2023]
Abstract
CONTEXT Metabolic imaging studying brown adipose tissue (BAT) physiology has increased, in which computed tomography (CT) is commonly used as an anatomical reference for metabolic positron emission tomography (PET) imaging. However, the capacity of CT to provide metabolic information has been underexploited. OBJECTIVE To evaluate whether CT radiodensity of BAT could noninvasively estimate underlying tissue morphology, regarding amount of stored triglycerides. Furthermore, could the alteration in tissue characteristics due to cold stimulus, as a marker for active BAT, be detected with radiodensity? Can BAT be differentiated from white adipose tissue (WAT) solely using CT-based measurements? DESIGN, SETTING, AND PARTICIPANTS A cross-sectional study evaluating 66 healthy human subjects with CT, PET, and 1H-magnetic resonance spectroscopy (1H-MRS). MAIN OUTCOME MEASURES BAT radiodensity was measured with CT. BAT-stored triglyceride content was measured with 1H-MRS. Arterial blood volume in BAT, as a marker of tissue vascularity, was measured with [15O]H2O, along with glucose or fatty acid uptake using [18F]2-fluoro-2-deoxy-D-glucose or 14(R,S)-[18F]fluoro-6-thia-heptadecanoic acid PET imaging, respectively. RESULTS BAT radiodensity was found to be correlating with tissue-retained blood and triglyceride content. Cold stimulus induced an increase in BAT radiodensity. Active BAT depots had higher radiodensity than both nonactive BAT and WAT. BAT radiodensity associated with systemic metabolic health parameters. CONCLUSION BAT radiodensity can be used as a marker of underlying tissue morphology. Active BAT can be identified using CT, exploiting tissue composition information. Moreover, BAT radiodensity provides an insight into whole-body systemic metabolic health.
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Affiliation(s)
- Mueez U Din
- Turku PET Centre, Turku University Hospital, 20520 Turku, Finland
- Turku PET Centre, University of Turku, 20520 Turku, Finland
| | - Juho Raiko
- Turku PET Centre, Turku University Hospital, 20520 Turku, Finland
- Turku PET Centre, University of Turku, 20520 Turku, Finland
| | - Teemu Saari
- Turku PET Centre, Turku University Hospital, 20520 Turku, Finland
- Turku PET Centre, University of Turku, 20520 Turku, Finland
| | - Virva Saunavaara
- Turku PET Centre, Turku University Hospital, 20520 Turku, Finland
| | - Nobu Kudomi
- Department of Medical Physics, Faculty of Medicine, Kagawa University, Kagawa 761-0793, Japan
| | - Olof Solin
- Turku PET Centre, Department of Chemistry, University of Turku and Accelerator Laboratory, Åbo Akademi University, 20520 Turku, Finland
| | - Riitta Parkkola
- Department of Radiology, Turku University Hospital and University of Turku, 20520 Turku, Finland
| | - Pirjo Nuutila
- Turku PET Centre, Turku University Hospital, 20520 Turku, Finland
- Turku PET Centre, University of Turku, 20520 Turku, Finland
| | - Kirsi A Virtanen
- Turku PET Centre, Turku University Hospital, 20520 Turku, Finland
- Turku PET Centre, University of Turku, 20520 Turku, Finland
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30
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Holstila M, Pesola M, Saari T, Koskensalo K, Raiko J, Borra RJH, Nuutila P, Parkkola R, Virtanen KA. MR signal-fat-fraction analysis and T2* weighted imaging measure BAT reliably on humans without cold exposure. Metabolism 2017; 70:23-30. [PMID: 28403942 DOI: 10.1016/j.metabol.2017.02.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 01/19/2017] [Accepted: 02/01/2017] [Indexed: 01/04/2023]
Abstract
OBJECTIVE Brown adipose tissue (BAT) is compositionally distinct from white adipose tissue (WAT) in terms of triglyceride and water content. In adult humans, the most significant BAT depot is localized in the supraclavicular area. Our aim is to differentiate brown adipose tissue from white adipose tissue using fat T2* relaxation time mapping and signal-fat-fraction (SFF) analysis based on a commercially available modified 2-point-Dixon (mDixon) water-fat separation method. We hypothesize that magnetic resonance (MR) imaging can reliably measure BAT regardless of the cold-induced metabolic activation, with BAT having a significantly higher water and iron content compared to WAT. MATERIAL AND METHODS The supraclavicular area of 13 volunteers was studied on 3T PET-MRI scanner using T2* relaxation time and SFF mapping both during cold exposure and at ambient temperature; and 18F-FDG PET during cold exposure. Volumes of interest (VOIs) were defined semiautomatically in the supraclavicular fat depot, subcutaneous WAT and muscle. RESULTS The supraclavicular fat depot (assumed to contain BAT) had a significantly lower SFF and fat T2* relaxation time compared to subcutaneous WAT. Cold exposure did not significantly affect MR-based measurements. SFF and T2* values measured during cold exposure and at ambient temperature correlated inversely with the glucose uptake measured by 18F-FDG PET. CONCLUSIONS Human BAT can be reliably and safely assessed using MRI without cold activation and PET-related radiation exposure.
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Affiliation(s)
- Milja Holstila
- Turku PET Centre, Turku University Hospital, Turku, Finland; Turku PET Centre, University of Turku, Turku, Finland; Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku, Finland.
| | - Marko Pesola
- Medical Imaging and Radiation Therapy, Carea, Kymenlaakso Social and Health Services, Kotka, Finland
| | - Teemu Saari
- Turku PET Centre, University of Turku, Turku, Finland
| | | | - Juho Raiko
- Turku PET Centre, Turku University Hospital, Turku, Finland; Turku PET Centre, University of Turku, Turku, Finland
| | - Ronald J H Borra
- Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku, Finland; Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Pirjo Nuutila
- Turku PET Centre, Turku University Hospital, Turku, Finland; Turku PET Centre, University of Turku, Turku, Finland
| | - Riitta Parkkola
- Turku PET Centre, University of Turku, Turku, Finland; Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku, Finland
| | - Kirsi A Virtanen
- Turku PET Centre, Turku University Hospital, Turku, Finland; Turku PET Centre, University of Turku, Turku, Finland
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Koskensalo K, Raiko J, Saari T, Saunavaara V, Eskola O, Nuutila P, Saunavaara J, Parkkola R, Virtanen KA. Human Brown Adipose Tissue Temperature and Fat Fraction Are Related to Its Metabolic Activity. J Clin Endocrinol Metab 2017; 102:1200-1207. [PMID: 28323929 DOI: 10.1210/jc.2016-3086] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 02/14/2017] [Indexed: 01/04/2023]
Abstract
BACKGROUND AND AIM The metabolic activity of human brown adipose tissue (BAT) has been previously examined using positron emission tomography (PET). The aim of this study was to use proton magnetic resonance spectroscopy (1H MRS) to investigate whether the temperature and the fat fraction (FF) of BAT and white adipose tissue (WAT) are associated with BAT metabolic activity determined by deoxy-2-18F-fluoro-d-glucose (18F-FDG)-PET. MATERIALS AND METHODS Ten healthy subjects (four women, six men; 25 to 45 years of age) were studied using PET-magnetic resonance imaging during acute cold exposure and at ambient room temperature. BAT and subcutaneous WAT 1H MRS were measured. The tissue temperature and the FF were derived from the spectra. Tissue metabolic activity was studied through glucose uptake using dynamic FDG PET scanning during cold exposure. A 2-hour hyperinsulinemic euglycemic clamp was performed on eight subjects. RESULTS The metabolic activity of BAT associated directly with the heat production capacity and inversely with the FF of the tissue. In addition, the lipid-burning capacity of BAT associated with whole-body insulin sensitivity. During cold exposure, the FF of BAT was lower than at room temperature, and cold-induced FF of BAT associated inversely with high-density lipoprotein and directly with low-density lipoprotein cholesterol. CONCLUSION Both 1H MRS-derived temperature and FF are promising methods to study BAT activity noninvasively. The association between the lipid-burning capacity of BAT and whole-body insulin sensitivity emphasizes the role of BAT in glucose handling. Furthermore, the relation of FF to high-density lipoprotein and low-density lipoprotein cholesterol suggests that BAT has a role in lipid clearance, thus protecting tissues from excess lipid load.
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Affiliation(s)
| | | | | | | | | | | | | | - Riitta Parkkola
- Department of Radiology, University of Turku, 20520 Turku, Finland
- Medical Imaging Centre of Southwest Finland, and
- Department of Radiology, Turku University Hospital, 20520 Turku, Finland
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32
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Koksharova E, Ustyuzhanin D, Philippov Y, Mayorov A, Shestakova M, Shariya M, Ternovoy S, Dedov I. The Relationship Between Brown Adipose Tissue Content in Supraclavicular Fat Depots and Insulin Sensitivity in Patients with Type 2 Diabetes Mellitus and Prediabetes. Diabetes Technol Ther 2017; 19:96-102. [PMID: 28118051 PMCID: PMC5278804 DOI: 10.1089/dia.2016.0360] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
BACKGROUND The evaluation of brown adipose tissue (BAT) and its role in metabolism and obesity remains an important topic in the recent literature. This study evaluated the influence of the BAT triglyceride content measured by proton magnetic resonance (MR) spectroscopy in patients with type 2 diabetes mellitus (DM2) and prediabetes on insulin sensitivity. METHODS A total of 25 patients with DM2 and prediabetes (45.9 ± 10.1 years old, body mass index [BMI] of 31.6 ± 5.4 kg/m2) underwent anthropometric measurements (BMI), insulin sensitivity analysis (M value during euglycemic hyperinsulinemic clamp and homeostasis model assessment of insulin resistance), proton MR spectroscopy, and blood tests (total cholesterol, low-density lipoproteins, high-density lipoproteins, and triglycerides). The relationship between the triglyceride content in the supraclavicular fat depot and insulin sensitivity, anthropometric measurements, and blood test results was assessed. RESULTS The triglyceride content in the supraclavicular fat depot varied between 79.2% and 97.1% (mean: 92.6% ± 4.2%). The triglyceride content in the subcutaneous white adipose tissue of the neck was significantly higher (85.3%-99.3%; mean: 95.5% ± 2.9%; P = 0.0007). The triglyceride content in the supraclavicular fat depot exhibited a significantly moderate correlation with the BMI (r = 0.64; P = 0.0009). A significant weak negative correlation between the supraclavicular fat content and M value was revealed (r = -0.44; P = 0.002). Patients with high insulin resistance (IR) had a higher triglyceride content in the supraclavicular fat depot than patients with normal and lower IR (94.3% ± 2.0% vs. 90.4% ± 5.2%; P = 0.02). CONCLUSIONS Reducing the BAT content in the supraclavicular fat depot can influence the development of IR in patients with DM2 and prediabetes.
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Affiliation(s)
| | | | | | - Alexander Mayorov
- Endocrinology Research Centre, Moscow, Russia
- I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Marina Shestakova
- Endocrinology Research Centre, Moscow, Russia
- I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | | | - Sergey Ternovoy
- I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Ivan Dedov
- Endocrinology Research Centre, Moscow, Russia
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Mitra S, Fernandez-Del-Valle M, Hill JE. The role of MRI in understanding the underlying mechanisms in obesity associated diseases. Biochim Biophys Acta Mol Basis Dis 2016; 1863:1115-1131. [PMID: 27639834 DOI: 10.1016/j.bbadis.2016.09.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 09/08/2016] [Accepted: 09/08/2016] [Indexed: 02/07/2023]
Abstract
Obesity and its possible association with diseases including diabetes and cardiovascular diseases have been studied for decades for its impact on healthcare. Recent studies clearly indicate the need for developing accurate and reproducible methodologies for assessing body fat content and distribution. Body fat distribution plays a significant role in developing an insight in the underlying mechanisms in which adipose tissue is linked with various diseases. Among imaging technologies including computerized axial tomography (CAT or CT), magnetic resonance imaging (MRI), and magnetic resonance spectroscopy (MRS), MRI and MRS seem to be the best emerging techniques and together are being considered as the gold standard for body fat content and distribution. This paper reviews studies up to the present time involving different methodologies of these two emerging technologies and presents the basic concepts of MRI and MRS with required novel image analysis techniques in accurate, quantitative, and direct assessment of body fat content and distribution. This article is part of a Special Issue entitled: Oxidative Stress and Mitochondrial Quality in Diabetes/Obesity and Critical Illness Spectrum of Diseases - edited by P. Hemachandra Reddy.
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Affiliation(s)
| | | | - Jason E Hill
- Texas Tech University, Lubbock, TX, United States
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34
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Smith DL, Yarar-Fisher C. Contributors to Metabolic Disease Risk Following Spinal Cord Injury. CURRENT PHYSICAL MEDICINE AND REHABILITATION REPORTS 2016; 4:190-199. [PMID: 29276654 PMCID: PMC5737009 DOI: 10.1007/s40141-016-0124-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Spinal cord injury (SCI) induced changes in neurological function have significant impact on the metabolism and subsequent metabolic-related disease risk in injured individuals. This metabolic-related disease risk relationship is differential depending on the anatomic level and severity of the injury, with high level anatomic injuries contributing a greater risk of glucose and lipid dysregulation resulting in type 2 diabetes and cardiovascular disease risk elevation. Although alterations in body composition, particularly excess adiposity and its anatomical distribution in the visceral depot or ectopic location in non-adipose organs, is known to significantly contribute to metabolic disease risk, changes in fat mass and fat-free mass do not fully account for this elevated disease risk in subjects with SCI. There are other negative adaptations in body composition including reductions in skeletal muscle mass and alterations in muscle fiber type, in addition to significant reduction in physical activity, that contribute to a decline in metabolic rate and increased metabolic disease risk following SCI. Recent studies in adult humans suggest cold- and diet-induced thermogenesis through brown adipose tissue metabolism may be important for energy balance and substrate metabolism, and particularly sensitive to sympathetic nervous signaling. Considering the alterations that occur in the autonomic nervous system (SNS) (sympathetic and parasympathetic) following a SCI, significant dysfunction of brown adipose function is expected. This review will highlight metabolic alterations following SCI and integrate findings from brown adipose tissue studies as potential new areas of research to pursue.
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Affiliation(s)
- Daniel L. Smith
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham AL, 35294 USA
- Nathan Shock Center of Excellence in the Basic Biology of Aging, University of Alabama at Birmingham, Birmingham AL, 35294 USA
- Comprehensive Center for Healthy Aging, University of Alabama at Birmingham, Birmingham AL, 35294 USA
- Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham AL, 35294 USA
| | - Ceren Yarar-Fisher
- Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham AL, 35294 USA
- Department of Physical Medicine and Rehabilitation, University of Alabama at Birmingham, Birmingham AL, 35294 USA
- Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham AL, 35294 USA
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Abstract
The demonstration of the presence of metabolically active brown adipose tissue (BAT) in adult humans using positron emission tomography (PET) over the past decade has lead to the rapid development of our knowledge regarding the role of BAT in energy metabolism in animal models and in humans. Although animal models continue to provide highly valuable information regarding the mechanisms regulating BAT development, mass and metabolic functions, these studies led to many assumptions that have been at best only partially verified in humans so far. Combined to some limitations of the current investigation approaches used in humans, this has lead to speculation on the potential role of BAT dysfunction in the development of cardiometabolic disorders and on the potential of BAT metabolic activation to treat these conditions. Here we propose a critical review of the evidence for the implication of BAT in cardiometabolic health.
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Affiliation(s)
- Denis P Blondin
- Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Canada
| | - André C Carpentier
- Department of Medicine, Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Canada.
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36
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Abstract
Human brown adipose tissue has been acknowledged in newborns and children but in adults the first printed publications are from the beginning of 20th century. Further evidence of the existence of adult brown fat was published throughout the century but only very recently the functionality of active brown adipose tissue in vivo in adulthood was confirmed. This was contributed mainly by advanced imaging technology, namely hybrid positron emission tomography (PET) and computed tomography (CT), being able to combine functional and anatomical imaging data. Functionality is most commonly measured with glucose analog, 18F-fluoro-2-deoxy-d-glucose (FDG) but other tracers for other functions than glucose uptake have been introduced as well. Growing body of evidence has increased the knowledge of the role of brown adipose tissue in human metabolism and energy expenditure, providing a promising option for the management of body weight balance and disturbed glucose and lipid metabolism.
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Affiliation(s)
- Kirsi A Virtanen
- Turku PET Centre, Turku University Hospital and University of Turku, Kiinamyllynkatu 4-8, 20520 Turku, Finland.
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37
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Abstract
Atherosclerosis, for which hyperlipidemia is a major risk factor, is the leading cause of morbidity and mortality in Western society, and new therapeutic strategies are highly warranted. Brown adipose tissue (BAT) is metabolically active in human adults. Although positron emission tomography-computed tomography using a glucose tracer is the golden standard to visualize and quantify the volume and activity of BAT, it has become clear that activated BAT combusts fatty acids rather than glucose. Here, we review the role of brown and beige adipocytes in lipoprotein metabolism and atherosclerosis, with evidence derived from both animal and human studies. On the basis of mainly data from animal models, we propose a model in which activated brown adipocytes use their intracellular triglyceride stores to generate fatty acids for combustion. BAT rapidly replenishes these stores by internalizing primarily lipoprotein triglyceride-derived fatty acids, generated by lipoprotein lipase-mediated hydrolysis of triglycerides, rather than by holoparticle uptake. As a consequence, BAT activation leads to the generation of lipoprotein remnants that are subsequently cleared via the liver provided that an intact apoE-low-density lipoprotein receptor pathway is present. Through these mechanisms, BAT activation reduces plasma triglyceride and cholesterol levels and attenuates diet-induced atherosclerosis development. Initial studies suggest that BAT activation in humans may also reduce triglyceride and cholesterol levels, but potential antiatherogenic effects should be assessed in future studies.
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Affiliation(s)
- Geerte Hoeke
- From the Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Sander Kooijman
- From the Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Mariëtte R Boon
- From the Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Patrick C N Rensen
- From the Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Jimmy F P Berbée
- From the Department of Medicine, Division of Endocrinology and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
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38
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Schilperoort M, Hoeke G, Kooijman S, Rensen PCN. Relevance of lipid metabolism for brown fat visualization and quantification. Curr Opin Lipidol 2016; 27:242-8. [PMID: 27023630 DOI: 10.1097/mol.0000000000000296] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE OF REVIEW Brown adipose tissue (BAT) is an emerging target to combat cardiometabolic disorders as it can take up substantial amounts of glucose and lipids from the circulation for heat production. This review focuses on new concepts in BAT physiology and discusses the need for new techniques to determine BAT activity in humans. RECENT FINDINGS Mouse studies showed that BAT activation selectively increases oxidation of lipids over glucose, by recruiting fatty acids from intracellular triglycerides. To replenish these intracellular lipid stores, brown adipocytes take up both glucose and triglyceride-derived fatty acids, resulting in attenuation of dyslipidaemia, insulin resistance and atherosclerosis. Clinical studies identified the involvement of the β3-adrenergic receptor in BAT activation and demonstrated that human BAT activation also selectively increases lipid oxidation. Notably, insulin resistance during ageing or weight gain reduces the capacity of BAT to internalize glucose, without reducing fatty acid uptake or oxidative metabolism. SUMMARY Preclinical studies established BAT as an important target to combat cardiometabolic disorders and elucidated underlying mechanisms whereas clinical studies identified therapeutic handles. Development of novel lipid-based PET-CT tracers and identification of translational biomarkers of BAT activity are required as alternatives to [F]fluorodeoxyglucose PET-CT to accelerate clinical development of BAT-activating therapeutic strategies.
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Affiliation(s)
- Maaike Schilperoort
- Department of Medicine, Division of Endocrinology, and Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands
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Iozzo P. Metabolic imaging in obesity: underlying mechanisms and consequences in the whole body. Ann N Y Acad Sci 2015; 1353:21-40. [PMID: 26335600 DOI: 10.1111/nyas.12880] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Obesity is a phenotype resulting from a series of causative factors with a variable risk of complications. Etiologic diversity requires personalized prevention and treatment. Imaging procedures offer the potential to investigate the interplay between organs and pathways underlying energy intake and consumption in an integrated manner, and may open the perspective to classify and treat obesity according to causative mechanisms. This review illustrates the contribution provided by imaging studies to the understanding of human obesity, starting with the regulation of food intake and intestinal metabolism, followed by the role of adipose tissue in storing, releasing, and utilizing substrates, including the interconversion of white and brown fat, and concluding with the examination of imaging risk indicators related to complications, including type 2 diabetes, liver pathologies, cardiac and kidney diseases, and sleep disorders. The imaging modalities include (1) positron emission tomography to quantify organ-specific perfusion and substrate metabolism; (2) computed tomography to assess tissue density as an indicator of fat content and browning/ whitening; (3) ultrasounds to examine liver steatosis, stiffness, and inflammation; and (4) magnetic resonance techniques to assess blood oxygenation levels in the brain, liver stiffness, and metabolite contents (triglycerides, fatty acids, glucose, phosphocreatine, ATP, and acetylcarnitine) in a variety of organs.
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Affiliation(s)
- Patricia Iozzo
- Institute of Clinical Physiology, National Research Council (CNR), Pisa, Italy.,The Turku PET Centre, University of Turku, Turku, Finland
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