scholarly journals Adipokines: inflammation and the pleiotropic role of white adipose tissue

2004 ◽  
Vol 92 (3) ◽  
pp. 347-355 ◽  
Author(s):  
Paul Trayhurn ◽  
I. Stuart Wood
Keyword(s):  
Adipose Tissue ◽  
Growth Factor ◽  
Inflammatory Cytokines ◽  
Acute Phase ◽  
White Adipose Tissue ◽  
Acute Phase Proteins ◽  
Endocrine Function ◽  
Low Grade ◽  
Circulating Levels

White adipose tissue is now recognised to be a multifunctional organ; in addition to the central role of lipid storage, it has a major endocrine function secreting several hormones, notably leptin and adiponectin, and a diverse range of other protein factors. These various protein signals have been given the collective name ‘adipocytokines’ or ‘adipokines’. However, since most are neither ‘cytokines’ nor ‘cytokine-like’, it is recommended that the term ‘adipokine’ be universally adopted to describe a protein that is secreted from (and synthesised by) adipocytes. It is suggested that the term is restricted to proteins secreted from adipocytes, excluding signals released only by the other cell types (such as macrophages) in adipose tissue. Theadipokinome(which together with lipid moieties released, such as fatty acids and prostaglandins, constitute thesecretomeof fat cells) includes proteins involved in lipid metabolism, insulin sensitivity, the alternative complement system, vascular haemostasis, blood pressure regulation and angiogenesis, as well as the regulation of energy balance. In addition, there is a growing list of adipokines involved in inflammation (TNFα, IL-1β, IL-6, IL-8, IL-10, transforming growth factor-β, nerve growth factor) and the acute-phase response (plasminogen activator inhibitor-1, haptoglobin, serum amyloid A). Production of these proteins by adipose tissue is increased in obesity, and raised circulating levels of several acute-phase proteins and inflammatory cytokines has led to the view that the obese are characterised by a state of chronic low-grade inflammation, and that this links causally to insulin resistance and the metabolic syndrome. It is, however, unclear as to the extent to which adipose tissue contributes quantitatively to the elevated circulating levels of these factors in obesity and whether there is a generalised or local state of inflammation. The parsimonious view is that the increased production of inflammatory cytokines and acute-phase proteins by adipose tissue in obesity relates primarily to localised events within the expanding fat depots. It is suggested that these events reflect hypoxia in parts of the growing adipose tissue mass in advance of angiogenesis, and involve the key controller of the cellular response to hypoxia, the transcription factor hypoxia inducible factor-1.

scholarly journals COVID-19 and Obesity: Role of Ectopic Visceral and Epicardial Adipose Tissues in Myocardial Injury

2021 ◽  
Vol 12 ◽  
Author(s):  
Adèle Lasbleiz ◽  
Bénédicte Gaborit ◽  
Astrid Soghomonian ◽  
Axel Bartoli ◽  
Patricia Ancel ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Intensive Care ◽  
Inflammatory Cytokines ◽  
Visceral Adipose Tissue ◽  
Cardiovascular Events ◽  
Low Grade ◽  
Viral Spread ◽  
Visceral Adipose ◽  
Pro Inflammatory Cytokines

In March 2020, the WHO declared coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a global pandemic. Obesity was soon identified as a risk factor for poor prognosis, with an increased risk of intensive care admissions and mechanical ventilation, but also of adverse cardiovascular events. Obesity is associated with adipose tissue, chronic low-grade inflammation, and immune dysregulation with hypertrophy and hyperplasia of adipocytes and overexpression of pro-inflammatory cytokines. However, to implement appropriate therapeutic strategies, exact mechanisms must be clarified. The role of white visceral adipose tissue, increased in individuals with obesity, seems important, as a viral reservoir for SARS-CoV-2 via angiotensin-converting enzyme 2 (ACE2) receptors. After infection of host cells, the activation of pro-inflammatory cytokines creates a setting conducive to the “cytokine storm” and macrophage activation syndrome associated with progression to acute respiratory distress syndrome. In obesity, systemic viral spread, entry, and prolonged viral shedding in already inflamed adipose tissue may spur immune responses and subsequent amplification of a cytokine cascade, causing worse outcomes. More precisely, visceral adipose tissue, more than subcutaneous fat, could predict intensive care admission; and lower density of epicardial adipose tissue (EAT) could be associated with worse outcome. EAT, an ectopic adipose tissue that surrounds the myocardium, could fuel COVID-19-induced cardiac injury and myocarditis, and extensive pneumopathy, by strong expression of inflammatory mediators that could diffuse paracrinally through the vascular wall. The purpose of this review is to ascertain what mechanisms may be involved in unfavorable prognosis among COVID-19 patients with obesity, especially cardiovascular events, emphasizing the harmful role of excess ectopic adipose tissue, particularly EAT.

scholarly journals Physiological role of adipose tissue: white adipose tissue as an endocrine and secretory organ

2001 ◽  
Vol 60 (3) ◽  
pp. 329-339 ◽  
Author(s):  
Paul Trayhurn ◽  
John H. Beattie
Keyword(s):  
Adipose Tissue ◽  
White Adipose Tissue ◽  
Physiological Role ◽  
Retinol Binding Protein ◽  
Endocrine Function ◽  
Specific Factor ◽  
Secretory Proteins ◽  
Metabolic Role ◽  
White Fat

The traditional role attributed to white adipose tissue is energy storage, fatty acids being released when fuel is required. The metabolic role of white fat is, however, complex. For example, the tissue is needed for normal glucose homeostasis and a role in inflammatory processes has been proposed. A radical change in perspective followed the discovery of leptin; this critical hormone in energy balance is produced principally by white fat, giving the tissue an endocrine function. Leptin is one of a number of proteins secreted from white adipocytes, which include angiotensinogen, adipsin, acylation-stimulating protein, adiponectin, retinol-binding protein, tumour neorosis factor a, interleukin 6, plasminogen activator inhibitor-1 and tissue factor. Some of these proteins are inflammatory cytokines, some play a role in lipid metabolism, while others are involved in vascular haemostasis or the complement system. The effects of specific proteins may be autocrine or paracrine, or the site of action may be distant from adipose tissue. The most recently described adipocyte secretory proteins are fasting-induced adipose factor, a fibrinogen–angiopoietin-related protein, metallothionein and resistin. Resistin is an adipose tissue-specific factor which is reported to induce insulin resistance, linking diabetes to obesity. Metallothionein is a metal-binding and stress-response protein which may have an antioxidant role. The key challenges in establishing the secretory functions of white fat are to identify the complement of secreted proteins, to establish the role of each secreted protein, and to assess the pathophysiological consequences of changes in adipocyte protein production with alterations in adiposity (obesity, fasting, cachexia). There is already considerable evidence of links between increased production of some adipocyte factors and the metabolic and cardiovascular complications of obesity. In essence, white adipose tissue is a major secretory and endocrine organ involved in a range of functions beyond simple fat storage.

scholarly journals The Role of Autophagy in White Adipose Tissue Function: Implications for Metabolic Health

Metabolites ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 179 ◽  
Author(s):  
Mercedes Clemente-Postigo ◽  
Alberto Tinahones ◽  
Rajaa El Bekay ◽  
María M. Malagón ◽  
Francisco J. Tinahones
Keyword(s):  
Adipose Tissue ◽  
White Adipose Tissue ◽  
Current Data ◽  
Metabolic Health ◽  
Diabetic Patients ◽  
Low Grade ◽  
Obesity And Diabetes ◽  
Cell Remodeling ◽  
Low Grade Inflammation

White adipose tissue (WAT) is a highly adaptive endocrine organ that continuously remodels in response to nutritional cues. WAT expands to store excess energy by increasing adipocyte number and/or size. Failure in WAT expansion has serious consequences on metabolic health resulting in altered lipid, glucose, and inflammatory profiles. Besides an impaired adipogenesis, fibrosis and low-grade inflammation also characterize dysfunctional WAT. Nevertheless, the precise mechanisms leading to impaired WAT expansibility are yet unresolved. Autophagy is a conserved and essential process for cellular homeostasis, which constitutively allows the recycling of damaged or long-lived proteins and organelles, but is also highly induced under stress conditions to provide nutrients and remove pathogens. By modulating protein and organelle content, autophagy is also essential for cell remodeling, maintenance, and survival. In this line, autophagy has been involved in many processes affected during WAT maladaptation, including adipogenesis, adipocyte, and macrophage function, inflammatory response, and fibrosis. WAT autophagy dysregulation is related to obesity and diabetes. However, it remains unclear whether WAT autophagy alteration in obese and diabetic patients are the cause or the consequence of WAT malfunction. In this review, current data regarding these issues are discussed, focusing on evidence from human studies.

scholarly journals The Secret Life of Fat: What are Fat Cells Doing for the Regulation of Metabolism

2008 ◽  
Vol 27 (4) ◽  
pp. 401-408
Author(s):  
Anna Tzontcheva
Keyword(s):  
Adipose Tissue ◽  
Growth Factor ◽  
Transforming Growth Factor Beta ◽  
Transforming Growth Factor ◽  
Acute Phase Proteins ◽  
Endocrine Function ◽  
Fat Cells ◽  
Plasminogen Activator Inhibitor 1 ◽  
Amyloid A ◽  
Regulation Of Metabolism

The Secret Life of Fat: What are Fat Cells Doing for the Regulation of MetabolismAdipose tissue has long been regarded as an organ the sole purpose of which was to store excess energy as triglycerides, and release energy as free fatty acids, which itself is an essential self-defense system for survival during starvation. This point of view has now changed, fat tissue has emerged as an endocrine and secretory organ affecting more than one metabolic pathway. Its major endocrine function is secreting several hormones, notably leptin and adiponectin. Also, adipose tissue releases adipo-kines involved in inflammation and hemostasis: growth factors (TNFα, transforming growth factor-beta, nerve growth factor, VEGF), cytokines (IL-1β, IL-6, IL-10), chemokines (IL-8), acute-phase proteins (haptoglobin, serum amyloid A) and prothrombotic factor (plasminogen activator inhibitor-1). This review aims to present some of the recent topics of selected adipokine research that may be of particular importance.

The Role of Epicardial Adipose Tissue Lymphocytes in Low-Grade Inflammation and Coronary Artery Disease

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 469-P
Author(s):  
MILOS MRAZ ◽  
ANNA CINKAJZLOVA ◽  
ZDENA LACINOVÁ ◽  
JANA KLOUCKOVA ◽  
HELENA KRATOCHVILOVA ◽  
...  
Keyword(s):  
Coronary Artery Disease ◽  
Adipose Tissue ◽  
Coronary Artery ◽  
Epicardial Adipose Tissue ◽  
Low Grade ◽  
Artery Disease ◽  
Low Grade Inflammation

scholarly journals Orphan GPR116 mediates the insulin sensitizing effects of the hepatokine FNDC4 in adipose tissue

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Anastasia Georgiadi ◽  
Valeria Lopez-Salazar ◽  
Rabih El- Merahbi ◽  
Rhoda Anane Karikari ◽  
Xiaochuan Ma ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
White Adipose Tissue ◽  
Dependent Manner ◽  
Metabolic Dysfunction ◽  
Functional Interaction ◽  
White Adipocyte ◽  
White Adipocytes ◽  
Obesity And Diabetes ◽  
Adhesion Gpcr ◽  
Circulating Levels

AbstractThe proper functional interaction between different tissues represents a key component in systemic metabolic control. Indeed, disruption of endocrine inter-tissue communication is a hallmark of severe metabolic dysfunction in obesity and diabetes. Here, we show that the FNDC4-GPR116, liver-white adipose tissue endocrine axis controls glucose homeostasis. We found that the liver primarily controlled the circulating levels of soluble FNDC4 (sFNDC4) and lowering of the hepatokine FNDC4 led to prediabetes in mice. Further, we identified the orphan adhesion GPCR GPR116 as a receptor of sFNDC4 in the white adipose tissue. Upon direct and high affinity binding of sFNDC4 to GPR116, sFNDC4 promoted insulin signaling and insulin-mediated glucose uptake in white adipocytes. Indeed, supplementation with FcsFNDC4 in prediabetic mice improved glucose tolerance and inflammatory markers in a white-adipocyte selective and GPR116-dependent manner. Of note, the sFNDC4-GPR116, liver-adipose tissue axis was dampened in (pre) diabetic human patients. Thus our findings will now allow for harnessing this endocrine circuit for alternative therapeutic strategies in obesity-related pre-diabetes.

scholarly journals Emerging Roles for Browning of White Adipose Tissue in Prostate Cancer Malignant Behaviour

2021 ◽  
Vol 22 (11) ◽  
pp. 5560
Author(s):  
Alejandro Álvarez-Artime ◽  
Belén García-Soler ◽  
Rosa María Sainz ◽  
Juan Carlos Mayo
Keyword(s):  
Prostate Cancer ◽  
Adipose Tissue ◽  
White Adipose Tissue ◽  
Tumor Development ◽  
Cell Types ◽  
Protective Role ◽  
Bioactive Molecules ◽  
Brown Adipose ◽  
Endocrine Organs

In addition to its well-known role as an energy repository, adipose tissue is one of the largest endocrine organs in the organism due to its ability to synthesize and release different bioactive molecules. Two main types of adipose tissue have been described, namely white adipose tissue (WAT) with a classical energy storage function, and brown adipose tissue (BAT) with thermogenic activity. The prostate, an exocrine gland present in the reproductive system of most mammals, is surrounded by periprostatic adipose tissue (PPAT) that contributes to maintaining glandular homeostasis in conjunction with other cell types of the microenvironment. In pathological conditions such as the development and progression of prostate cancer, adipose tissue plays a key role through paracrine and endocrine signaling. In this context, the role of WAT has been thoroughly studied. However, the influence of BAT on prostate tumor development and progression is unclear and has received much less attention. This review tries to bring an update on the role of different factors released by WAT which may participate in the initiation, progression and metastasis, as well as to compile the available information on BAT to discuss and open a new field of knowledge about the possible protective role of BAT in prostate cancer.

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