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Cell Proliferation Feb 2016Exosomes are nanovesicles that have emerged as a new intercellular communication system for transporting proteins and RNAs; recent studies have shown that they play a... (Review)
Review
Exosomes are nanovesicles that have emerged as a new intercellular communication system for transporting proteins and RNAs; recent studies have shown that they play a role in many physiological and pathological processes such as immune regulation, cell differentiation, infection and cancer. By transferring proteins, mRNAs and microRNAs, exosomes act as information vehicles that alter the behavior of recipient cells. Compared to direct cell-cell contact or secreted factors, exosomes can affect recipient cells in more efficient ways. In whole adipose tissues, it has been shown that exosomes exist in supernatants of adipocytes and adipose stromal cells (ADSCs). Adipocyte exosomes are linked to lipid metabolism and obesity-related insulin resistance and exosomes secreted by ADSCs are involved in angiogenesis, immunomodulation and tumor development. This review introduces characteristics of exosomes in adipose tissue, summarizes their functions in different physiological and pathological processes and provides the further insight into potential application of exosomes to disease diagnosis and treatment.
Topics: Adipose Tissue; Animals; Exosomes; Humans; Models, Biological
PubMed: 26776755
DOI: 10.1111/cpr.12233 -
Frontiers in Immunology 2018Ageing, like obesity, is often associated with alterations in metabolic and inflammatory processes resulting in morbidity from diseases characterised by poor metabolic... (Review)
Review
Ageing, like obesity, is often associated with alterations in metabolic and inflammatory processes resulting in morbidity from diseases characterised by poor metabolic control, insulin insensitivity, and inflammation. Ageing populations also exhibit a decline in immune competence referred to as immunosenescence, which contributes to, or might be driven by chronic, low-grade inflammation termed "inflammageing". In recent years, animal and human studies have started to uncover a role for immune cells within the stromal fraction of adipose tissue in driving the health complications that come with obesity, but relatively little work has been conducted in the context of immunometabolic adipose function in ageing. It is now clear that aberrant immune function within adipose tissue in obesity-including an accumulation of pro-inflammatory immune cell populations-plays a major role in the development of systemic chronic, low-grade inflammation, and limiting the function of adipocytes leading to an impaired fat handling capacity. As a consequence, these changes increase the chance of multiorgan dysfunction and disease onset. Considering the important role of the immune system in obesity-associated metabolic and inflammatory diseases, it is critically important to further understand the interplay between immunological processes and adipose tissue function, establishing whether this interaction contributes to age-associated immunometabolic dysfunction and inflammation. Therefore, the aim of this article is to summarise how the interaction between adipose tissue and the immune system changes with ageing, likely contributing to the age-associated increase in inflammatory activity and loss of metabolic control. To understand the potential mechanisms involved, parallels will be drawn to the current knowledge derived from investigations in obesity. We also highlight gaps in research and propose potential future directions based on the current evidence.
Topics: Adipocytes; Adipose Tissue; Aging; Animals; Disease Models, Animal; Humans; Immunosenescence; Inflammation; Mice; Obesity
PubMed: 29479350
DOI: 10.3389/fimmu.2018.00169 -
Diabetologia Jan 2019White adipose tissue is a highly plastic organ and is an important regulator of whole-body metabolism and energy balance. The magnitude of adipose tissue mass is... (Review)
Review
White adipose tissue is a highly plastic organ and is an important regulator of whole-body metabolism and energy balance. The magnitude of adipose tissue mass is determined by dynamic changes in the synthesis and breakdown (i.e. turnover) of adipocytes and triacylglycerols (TGs). Obesity is a disorder characterised by excessive adiposity and is a risk factor for diseases, including the metabolic syndrome and type 2 diabetes. Adipose tissue expansion is necessary to accommodate chronic excess energy intake and is characterised by enlargement of existing adipocytes (hypertrophy) and by increase in pre-adipocyte and adipocyte numbers (hyperplasia). Evidence suggests that the manner of subcutaneous adipose expansion can influence metabolic health, as impaired adipogenesis, namely restricted hyperplasia, may lead to ectopic lipid deposition in the liver and skeletal muscle, contributing to the pathogenesis of obesity-related disorders. Despite the plausible role of adipose turnover in human health and pathology, little is known about the in vivo kinetics of adipose tissue components (both adipose cells and TGs). This is due, in part, to the slow turnover rate of adipose tissue and the complexity of directly labelling pathway precursors. This review provides a brief summary of findings derived from in vitro techniques, as well as an overview of two in vivo methods that are being implemented to assess the turnover of adipose cells and TGs. Finally, the role of adipose tissue turnover in metabolic health and disease is discussed.
Topics: Adipocytes; Adipose Tissue; Adipose Tissue, White; Diabetes Mellitus, Type 2; Humans; Obesity; Triglycerides
PubMed: 30267179
DOI: 10.1007/s00125-018-4732-x -
The FEBS Journal Mar 2020Obesity is often associated with high systemic and local renin-angiotensin system (RAS) activity in adipose tissue. Adipose-derived mesenchymal stem/stromal cells... (Review)
Review
Obesity is often associated with high systemic and local renin-angiotensin system (RAS) activity in adipose tissue. Adipose-derived mesenchymal stem/stromal cells (ADSCs), responsible for adipose tissue growth upon high-fat diet, express multiple angiotensin II receptor isoforms, including angiotensin II type 1 receptor (AT R), angiotensin II type 2 receptor (AT R), Mas and Mas-related G protein-coupled receptor D. Although AT R is expressed on most ADSCs, other angiotensin receptors are co-expressed on a small subpopulation of the cells, a phenomenon that results in a complex response pattern. Following AT R activation, the effects are transient due to rapid receptor internalisation. This short-lived effect can be prevented by heteromerisation with AT R, a particularly important strategy for the regulation of ADSC differentiation and secretory activity. Heteromeric AT R might be especially important for the generation of thermogenic beige adipocytes. This review summarises current data regarding the regulation of adipose tissue renewal and particularly ADSC adipogenic differentiation and secretory activity by RAS, with an emphasis on AT R and its effects. We reveal a new scheme that implicates AT R into the regulation of ADSC hormonal sensitivity.
Topics: Adipose Tissue; Animals; Cell Proliferation; Humans; Receptor, Angiotensin, Type 2
PubMed: 31899581
DOI: 10.1111/febs.15200 -
European Journal of Pharmacology Dec 2017Obesity is a well-established risk factor for atherosclerosis. However, the mechanistic link between accumulation of adipose tissue and development of atherosclerosis is... (Review)
Review
Obesity is a well-established risk factor for atherosclerosis. However, the mechanistic link between accumulation of adipose tissue and development of atherosclerosis is not clear. Adipose tissue comprises various depots including white adipose tissue (WAT), brown adipose tissue (BAT) and thoracic and abdominal perivascular adipose tissue (PVAT). The phenotype of thoracic PVAT resembles BAT, whereas abdominal PVAT is more like WAT. Here, we review the distinct roles of the adipose tissue depots in the development of atherosclerosis with the ultimate aim to understand how these can be targeted to reduce atherosclerosis. In obesity, increased fatty acid release by WAT and decreased lipid combustion by BAT and thoracic PVAT lead to hyperlipidaemia, which contributes to atherosclerosis development. Besides, obese WAT and abdominal PVAT release pro-inflammatory factors that further promote atherosclerosis. To discourage atherosclerosis development, strategies that reduce the release of pro-inflammatory factors and fatty acids from WAT and abdominal PVAT, or increase combustion of fatty acids by activation of BAT and thoracic PVAT and beiging of WAT are probably most efficient. Possible therapies could include anti-inflammatory compounds such as adiponectin and salicylates to lower inflammation, and β3-adrenergic receptor activators to increase fatty acid combustion. Additional and more specific strategies to promote fatty acid combustion are currently subject of investigation. In conclusion, different adipose depots differentially affect atherosclerosis development, in which atherosclerosis is promoted by energy-storing adipose depots and attenuated by energy-combusting adipose tissue. In obesity, combining therapies that reduce inflammation and increase combustion of lipids are most conceivable to restrain atherogenesis.
Topics: Adipose Tissue, Brown; Adipose Tissue, White; Animals; Atherosclerosis; Blood Vessels; Humans; Molecular Targeted Therapy
PubMed: 28347739
DOI: 10.1016/j.ejphar.2017.03.051 -
Tomography (Ann Arbor, Mich.) Feb 2022Background: Specification of adipose tissues by whole-body magnetic resonance imaging (MRI) was performed and related to pulmonary function parameters in a...
Background: Specification of adipose tissues by whole-body magnetic resonance imaging (MRI) was performed and related to pulmonary function parameters in a population-based cohort. Methods: 203 study participants underwent whole-body MRI and pulmonary function tests as part of the KORA (Cooperative Health Research in the Augsburg Region) MRI study. Both visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were derived from the T1-Dixon sequence, and hepatic adipose tissue from the proton density fat fraction (PDFFhepatic). Associations between adipose tissue parameters and spirometric indices such as forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and Tiffeneau-index (FEV1/FVC) were examined using multivariate linear regression analysis excluding cofounding effects of other clinical parameters. Results: VAT (β = −0.13, p = 0.03) and SAT (β = −0.26, p < 0.001), but not PDFFhepatic were inversely associated with FEV1, while VAT (β = −0.27, p < 0.001), SAT (β = −0.41, p < 0.001), and PDFFhepatic (β = −0.17, p = 0.002) were inversely associated with FVC. PDFFhepatic was directly associated with the Tiffeneau index (β = 2.46, p < 0.001). Conclusions: In the adjusted linear regression model, VAT was inversely associated with all measured spirometric parameters, while PDFFhepatic revealed the strongest association with the Tiffeneau index. Non-invasive adipose tissue quantification measurements might serve as novel biomarkers for respiratory impairment.
Topics: Adipose Tissue; Humans; Intra-Abdominal Fat; Magnetic Resonance Imaging; Subcutaneous Fat; Whole Body Imaging
PubMed: 35314623
DOI: 10.3390/tomography8020046 -
Experimental & Molecular Medicine Mar 2016Adipose tissue is a highly heterogeneous endocrine organ. The heterogeneity among different anatomical depots stems from their intrinsic differences in cellular and... (Review)
Review
Adipose tissue is a highly heterogeneous endocrine organ. The heterogeneity among different anatomical depots stems from their intrinsic differences in cellular and physiological properties, including developmental origin, adipogenic and proliferative capacity, glucose and lipid metabolism, insulin sensitivity, hormonal control, thermogenic ability and vascularization. Additional factors that influence adipose tissue heterogeneity are genetic predisposition, environment, gender and age. Under obese condition, these depot-specific differences translate into specific fat distribution patterns, which are closely associated with differential cardiometabolic risks. For instance, individuals with central obesity are more susceptible to developing diabetes and cardiovascular complications, whereas those with peripheral obesity are more metabolically healthy. This review summarizes the clinical and mechanistic evidence for the depot-specific differences that give rise to different metabolic consequences, and provides therapeutic insights for targeted treatment of obesity.
Topics: Adipose Tissue; Adipose Tissue, White; Animals; Energy Metabolism; Humans; Mechanical Phenomena; Obesity
PubMed: 26964831
DOI: 10.1038/emm.2016.5 -
Obesity (Silver Spring, Md.) Jan 2023The goal of this study was to review the metabolic effects of fat transplantation. (Review)
Review
OBJECTIVE
The goal of this study was to review the metabolic effects of fat transplantation.
METHODS
Fat (adipose tissue [AT]) transplantation has been performed extensively for many years in the cosmetic reconstruction industry. However, not all fats are equal. White, brown, and beige AT differ in energy storage and use. Brown and beige AT consume glucose and lipids for thermogenesis and, theoretically, may provide greater metabolic benefit in transplantation. Here, the authors review the metabolic effects of AT transplantation.
RESULTS
Removal of subcutaneous human AT does not have beneficial metabolic effects. Most studies find no benefit from visceral AT transplantation and some studies report harmful effects. In contrast, transplantation of inguinal or subcutaneous AT in mice has positive effects. Brown AT transplant studies have variable results depending on the model but most show benefit.
CONCLUSIONS
Many technical improvements have optimized fat grafting and transplantation in cosmetic surgery. Transplantation of subcutaneous AT has the potential for significant metabolic benefits, although there are few studies in humans or using human AT. Brown AT transplantation is beneficial but not readily feasible in humans thus ex vivo "beiging" may be a useful strategy. AT transplantation may provide clinical benefits in metabolic disorders, especially in the setting of lipodystrophy.
Topics: Mice; Humans; Animals; Lipectomy; Adipose Tissue; Adipose Tissue, Brown; Subcutaneous Fat; Adipose Tissue, Beige; Glucose; Thermogenesis; Adipose Tissue, White
PubMed: 36479639
DOI: 10.1002/oby.23601 -
Antioxidants & Redox Signaling Jul 2018Obesity and diabetes are associated with chronic activation of inflammatory pathways that are important mechanistic links between insulin resistance (IR), type 2... (Review)
Review
SIGNIFICANCE
Obesity and diabetes are associated with chronic activation of inflammatory pathways that are important mechanistic links between insulin resistance (IR), type 2 diabetes (T2D), and cardiovascular disease pathogenesis. The development of these metabolic diseases is associated with changes in both the number and phenotype of adipose tissue macrophages (ATMs). Emerging lines of evidence have shown that ATMs release proinflammatory cytokines similar to classically activated M1 macrophages, which directly contribute to IR or T2D. In contrast, adipose tissue (AT) from lean healthy individuals contains macrophages with a less inflammatory M2 phenotype. Recent Advances: Recent research has shown that macrophage phenotype is linked to profound changes in macrophage cellular metabolism.
CRITICAL ISSUES
This review focuses on the role of macrophages in AT inflammation and obesity, and the metabolic changes in macrophage function that occur with activation that underpin their role in the pathogenesis of IR and T2D. We highlight current targets for altering macrophage metabolism from both within the field of metabolic disease and AT biology and more widely within inflammatory biology.
FUTURE DIRECTIONS
As our knowledge of macrophage metabolic programming in AT builds, there will be increasing scope for targeting this aspect of macrophage biology as a therapeutic strategy in metabolic diseases. Antioxid. Redox Signal. 29, 297-312.
Topics: Adipose Tissue; Animals; Diabetes Mellitus, Type 2; Humans; Macrophages; Obesity
PubMed: 28661198
DOI: 10.1089/ars.2017.7060 -
Missouri Medicine 2014Our current environment has led to a vicious cycle of physical inactivity, obesity, and chronic inflammation, creating the "perfect storm" for metabolic diseases. White... (Review)
Review
Our current environment has led to a vicious cycle of physical inactivity, obesity, and chronic inflammation, creating the "perfect storm" for metabolic diseases. White adipose tissue (WAT) is the major source of obesity/ inactivity-related inflammation; in turn, inflammation leads to insulin resistance and metabolic dysfunction. Inactivity, even in the absence of weight gain, disrupts WAT metabolism, while exercise mitigates WAT inflammation. The antiinflammatory mechanism(s) of exercise require additional study. Two current hypotheses include: (1) exercise-mediated antiinflammatory cytokine secretion, and (2) exercise-mediated improvements in adipocyte oxidative capacity.
Topics: Adipose Tissue; Energy Metabolism; Exercise; Humans; Inflammation; Insulin Resistance; Lipid Metabolism; Obesity
PubMed: 24645302
DOI: No ID Found