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International Journal of Molecular... Jul 2019Obesity is considered to significantly increase the risk of the development of a vast range of metabolic diseases. However, adipogenesis is a complex physiological... (Review)
Review
Obesity is considered to significantly increase the risk of the development of a vast range of metabolic diseases. However, adipogenesis is a complex physiological process, necessary to sequester lipids effectively to avoid lipotoxicity in other tissues, like the liver, heart, muscle, essential for maintaining metabolic homeostasis and has a crucial role as a component of the innate immune system, far beyond than only being an inert mass of energy storage. In pathophysiological conditions, adipogenesis promotes a pro-inflammatory state, angiogenesis and the release of adipokines, which become dangerous to health. It results in a hypoxic state, causing oxidative stress and the synthesis and release of harmful free fatty acids. In this review, we try to explain the mechanisms occurring at the breaking point, at which adipogenesis leads to an uncontrolled lipotoxicity. This review highlights the types of adipose tissue and their functions, their way of storing lipids until a critical point, which is associated with hypoxia, inflammation, insulin resistance as well as lipodystrophy and adipogenesis modulation by Krüppel-like factors and miRNAs.
Topics: Adipocytes; Adipogenesis; Adipose Tissue; Animals; Disease Susceptibility; Energy Metabolism; Humans; Lipogenesis; Panniculitis
PubMed: 31357412
DOI: 10.3390/ijms20153657 -
International Journal of Molecular... Aug 2021Brown adipose tissue (BAT), a uniquely thermogenic tissue that plays an important role in metabolism and energy expenditure, has recently become a revived target in the... (Review)
Review
Brown adipose tissue (BAT), a uniquely thermogenic tissue that plays an important role in metabolism and energy expenditure, has recently become a revived target in the fight against metabolic diseases, such as obesity, diabetes, and non-alcoholic fatty liver disease (NAFLD). Different from white adipose tissue (WAT), the brown adipocytes have distinctive features including multilocular lipid droplets, a large number of mitochondria, and a high expression of uncoupling protein-1 (UCP-1), as well as abundant capillarity. These histologic characteristics provide an opportunity to differentiate BAT from WAT using imaging modalities, such as PET/CT, SPECT/CT, MRI, NIRF and Ultrasound. However, most of the reported imaging methods were BAT activation dependent, and the imaging signals could be affected by many factors, including environmental temperatures and the states of the sympathetic nervous system. Accurate BAT mass detection methods that are independent of temperature and hormone levels have the capacity to track the development and changes of BAT throughout the lifetime of mammals, and such methods could be very useful for the investigation of potential BAT-related therapies. In this review, we focus on molecular imaging modalities that can detect and quantify BAT mass. In addition, their detection mechanism and limitations will be discussed as well.
Topics: Adipose Tissue, Brown; Adipose Tissue, White; Animals; Humans; Metabolic Diseases; Molecular Imaging
PubMed: 34502347
DOI: 10.3390/ijms22179436 -
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 -
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 -
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 -
Clinical Interventions in Aging 2017Age-dependent modification of the facial subcutaneous white adipose tissue (sWAT) connected with reduction of its volume, modification of collagen content and adhesion... (Review)
Review
Age-dependent modification of the facial subcutaneous white adipose tissue (sWAT) connected with reduction of its volume, modification of collagen content and adhesion between dermal and adipose layers can significantly influence mechanical stability of the skin and cause the development of aging symptoms such as wrinkles. Typical aging appearance in facial skin is at least partly connected with special phenotypical features of facial preadipocytes and mature adipocytes. In this paper, we have discussed the possible roles of local inflammation, compartmental structure of facial sWAT and trans-differentiation processes such as beiging of white adipocytes and adipocyte-myofibroblast transition in facial skin aging.
Topics: Adipocytes; Adipose Tissue; Adipose Tissue, White; Face; Humans; Phenotype; Skin Aging
PubMed: 29255352
DOI: 10.2147/CIA.S151599 -
Bioscience Reports Jun 2020Adipose tissue, the storage of excessive energy in the body, secretes various proteins called adipokines, which connect the body's nutritional status to the regulation... (Review)
Review
Adipose tissue, the storage of excessive energy in the body, secretes various proteins called adipokines, which connect the body's nutritional status to the regulation of energy balance. Obesity triggers alterations of quantity and quality of various types of cells that reside in adipose tissue, including adipose stem cells (ASCs; referred to as adipose-derived stem/stromal cells in vitro). These alterations in the functionalities and properties of ASCs impair adipose tissue remodeling and adipose tissue function, which induces low-grade systemic inflammation, progressive insulin resistance, and other metabolic disorders. In contrast, the ability of ASCs to recruit new adipocytes when faced with caloric excess leads to healthy adipose tissue expansion, associated with lower amounts of inflammation, fibrosis, and insulin resistance. This review focuses on recent advances in our understanding of the identity of ASCs and their roles in adipose tissue development, homeostasis, expansion, and thermogenesis, and how these roles go awry in obesity. A better understanding of the biology of ASCs and their adipogenesis may lead to novel therapeutic targets for obesity and metabolic disease.
Topics: Adipocytes; Adipogenesis; Adipokines; Adipose Tissue; Adiposity; Animals; Energy Metabolism; Humans; Obesity; Signal Transduction; Stem Cell Transplantation; Stem Cells
PubMed: 32452515
DOI: 10.1042/BSR20194076 -
Physiology & Behavior Jun 2018There is renewed interest in leveraging the thermogenic capacity of brown adipose tissue (BAT) and browning of white adipose tissue (WAT) to improve energy balance and... (Review)
Review
There is renewed interest in leveraging the thermogenic capacity of brown adipose tissue (BAT) and browning of white adipose tissue (WAT) to improve energy balance and prevent obesity. In addition to these effects on energy expenditure, both BAT and WAT secrete large numbers of hormones and cytokines that play important roles in maintaining metabolic health. Both BAT and WAT are densely innervated by the sympathetic nervous system (SNS) and this innervation is crucial for BAT thermogenesis and WAT browning, making it a potentially interesting target for manipulating energy balance and treatment of obesity and metabolic disease. Peripheral neuromodulation in the form of electrical manipulation of the SNS and parasympathetic nervous system (PSNS) has been used for the management of pain and many other conditions, but progress is hampered by lack of detailed knowledge of function-specific neurons and nerves innervating particular organs and tissues. Therefore, the goal of the National Institutes of Health (NIH) Common Fund project "Stimulating Peripheral Activity to Relieve Conditions (SPARC)" is to comprehensively map both anatomical and neurochemical aspects of the peripheral nervous system in animal model systems to ultimately guide optimal neuromodulation strategies in humans. Compared to electrical manipulation, neuron-specific opto- and chemogenetic manipulation, now being extensively used to decode the function of brain circuits, will further increase the functional specificity of peripheral neuromodulation.
Topics: Adipose Tissue, Brown; Adipose Tissue, White; Animals; Genetic Techniques; Parasympathetic Nervous System; Sympathetic Nervous System
PubMed: 28859876
DOI: 10.1016/j.physbeh.2017.08.024 -
Scientific Reports Nov 2020Body contouring achieved via subcutaneous adipose tissue reduction has notably advanced over the past century, from suction assisted lipectomy to techniques with reduced...
Body contouring achieved via subcutaneous adipose tissue reduction has notably advanced over the past century, from suction assisted lipectomy to techniques with reduced degrees of invasiveness including laser, radiofrequency, high frequency focused ultrasound, cryolipolysis, and drug-based injection approaches. These costly techniques have focused on damaging adipocyte cell membranes, hydrolyzing triglycerides (TGs), or inducing apoptosis. Here, we present a simple, low-cost technique, termed electrochemical lipolysis (ECLL). During ECLL, saline is injected into the subcutaneous adipose tissue, followed by insertion of needle electrodes and application of an electrical potential. Electrolysis of saline creates localized pH gradients that drive adipocyte death and saponification of TGs. Using pH mapping, various optical imaging techniques, and biochemical assays, we demonstrate the ability of ECLL to induce acid and base injury, cell death, and the saponification of triglycerides in ex vivo porcine adipose tissue. We define ECLL's potential role as a minimally-invasive, ultra-low-cost technology for reducing and contouring adipose tissue, and present ECLL as a potential new application of an emerging electrochemical redox based treatment modality.
Topics: Adipose Tissue; Animals; Apoptosis; Body Contouring; Electrochemical Techniques; Hydrogen-Ion Concentration; Lipolysis; Swine; Triglycerides
PubMed: 33247200
DOI: 10.1038/s41598-020-76678-y -
Nature Reviews. Endocrinology Apr 2010Humans and other mammals have three main adipose tissue depots: visceral white adipose tissue, subcutaneous white adipose tissue and brown adipose tissue, each of which... (Review)
Review
Humans and other mammals have three main adipose tissue depots: visceral white adipose tissue, subcutaneous white adipose tissue and brown adipose tissue, each of which possesses unique cell-autonomous properties. In contrast to visceral adipose tissue, which can induce detrimental metabolic effects, subcutaneous white adipose tissue and brown adipose tissue have the potential to benefit metabolism by improving glucose homeostasis and increasing energy consumption. In addition, adipose tissue contains adipose-derived stem cells, which possess the ability to differentiate into multiple lineages, a property that might be of value for the repair or replacement of various damaged cell types. Adipose tissue transplantation has primarily been used as a tool to study physiology and for human reconstructive surgery. Transplantation of adipose tissue is, however, now being explored as a possible tool to promote the beneficial metabolic effects of subcutaneous white adipose tissue and brown adipose tissue, as well as adipose-derived stem cells. Ultimately, the clinical applicability of adipose tissue transplantation for the treatment of obesity and metabolic disorders will reside in the achievable level of safety, reliability and efficacy compared with other treatments.
Topics: Adipose Tissue; Animals; Disease; Humans; Metabolic Diseases; Metabolism; Models, Biological; Obesity; Stem Cell Transplantation; Stem Cells
PubMed: 20195269
DOI: 10.1038/nrendo.2010.20