Obesity and Health
James M. Rippe in Lifestyle Medicine, 2019
Historically, adipocytes were thought to be primarily storage sites for excess fat. Research over the past two decades, however, has demonstrated that adipocytes are, in fact, highly complicated, inflammatory endocrine and metabolic cells. Thus, adipose tissue essentially serves as a complex endocrine organ and a potent source of inflammatory molecules such as tumor necrosis factor-α (TNF α), interleukin-6, and many others.26,33–36 These complex properties of adipocytes may underlie the strong linkage between obesity and chronic metabolic conditions such as diabetes, coronary heart disease, and the metabolic syndrome. Adipocytes located in the abdominal region appear to be particularly complicated and active from a metabolic and inflammatory point of view.26–29
Liposarcoma
Dongyou Liu in Tumors and Cancers, 2017
Adipose tissue (or fat) is a loose connective tissue located beneath the skin (at the subcutaneous layer), between muscles, around the kidneys and heart, and behind the eyeballs and abdominal membranes. Two types of adipose tissue exist in the body, i.e. white adipose tissue (WAT) and brown adipose tissue (BAT). WAT is mostly made up of fat cells called adipocytes, which synthesize and store fat as lipid droplets in the middle, and whose nuclei are displaced to the side. BAT contains smaller brown fat cells, which derive their color from the high concentration of mitochondria for energy production and vascularization of the tissue. The main functions of adipose tissue are to store excess dietary fat (called triglycerides) inside the adipocytes, to cushion or absorb physical trauma, and to insulate or maintain the core body temperature.
ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
(from Latin, adepis: soft fat) Adipose tissue is what is more commonly known as fat; adiposity is a term indicating fatness. Adipose tissue (which is white—BROWN ADIPOSE TISSUE has a different function) consists of a matrix of CONNECTIVE TISSUE in which are held adipose cells (also called ADIPOCYTES). These cells contain TRIGLYCERIDES, which may be metabolized and released by adipocytes when there are ENERGY demands on the organism. Adipocytes have a necessary relation to adiposity. There are two factors that are important in this: one is the number of adipocytes that are present, and the second is their size (that is, how much fat each adipocyte actually contains). The number of adipocytes present in an organism is probably set initially by genetic factors but it has been shown that sustained periods of overfeeding can lead to adipocyte HYPERPLASIA. Controlling the size of adipocytes is relatively straightforward—reducing fat intake will do this—but reducing adipocyte number is harder to do, requiring very lengthy periods of intake restriction. There is another important question about the regulation of adipocytes: is fat storage regulated or merely a consequence of energy intake? Is the surplus energy that is neither used straightaway nor consumed in thermogenesis simply stored or are there active mechanisms governing adiposity? Until recently no identifiable signal from adipose tissue to brain mechanisms controlling intake could be detected, but the recent discovery of LEPTIN has suggested that there may indeed by a signal from adipocytes to the HYPOTHALAMUS that allows for regulation of adiposity.
Effects of different oxygen tensions on differentiated human preadipocytes lipid storage and mobilisation
Published in Archives of Physiology and Biochemistry, 2021
Bimit Mahat, Jean-François Mauger, Pascal Imbeault
Adipocytes, the signature cells of adipose tissue, play a central role in the regulation of lipid storage and lipid mobilisation (Luo and Liu 2016). Adipocytes store energy in excess of needs in the form of triglycerides (TG), a process termed lipogenesis that is partly driven by the lipoprotein lipase (LPL). LPL degrades lipoprotein-bound TG to fatty acids for their subsequent uptake by the adipocytes where they can be re-esterified into TG through the action of acyltransferases (MGAT (monoacylglycerol acyltransferase activity) and DGAT (diacylglycerol acyltransferase activity)) (Shi and Cheng 2009, Luo and Liu 2016). In addition, adipocytes can synthesise new fatty acids from other macronutrients, a process called de novo lipogenesis (DNL). Part of DNL regulation occurs at the transcriptional level through the nuclear factor carbohydrate response element-binding protein (ChREBP), which stimulates the expression of DNL rate-limiting enzymes acetyl-coA carboxylase (ACC) and fatty acid synthase (FASN) in response to increase in glucose availability (Shrago et al. 1969, Herman et al.2012). In time of increased metabolic need, stored lipids can be mobilised by converting adipocytes TG into fatty acids using a process called lipolysis, which depends mainly on the activation of two specific hydrolases, the adipose triglyceride lipase (ATGL) and the hormone-sensitive lipase (HSL) (Lass et al.2011). Fatty acids derived from intracellular lipolysis are released into circulation and delivered to peripheral tissues to sustain energy demand.
Personalized Nutrition: Translating the Science of NutriGenomics Into Practice: Proceedings From the 2018 American College of Nutrition Meeting
Published in Journal of the American College of Nutrition, 2019
Okezie I Aruoma, Sharon Hausman-Cohen, Jessica Pizano, Michael A. Schmidt, Deanna M. Minich, Yael Joffe, Sebastian Brandhorst, Simon J. Evans, David M. Brady
Profiling of genetic nutritional responses can help in the determination of which specific foods give the best biological response, based on an individual’s DNA. Of interest, fatty acids in dietary triacylglycerols are transported from the intestines to the rest of the body by large lipoprotein particles called chylomicrons. Hormone signaling releases fatty acids from adipose tissue that bind to an abundant transport protein in serum called albumin. The fatty acids that are synthesized in the liver are carried through the body as triacylglycerols by very-low-density lipoprotein particles. Fat is stored in fat cells (adipocytes). Obesity, especially childhood obesity, can be due to both, that is, more fat storage per cell and a larger number of adipocytes. In contrast, in normal healthy adults, the onset of old age and reduced metabolic rates leads to weight gain resulting primarily from storing more fat per cell (although adults can also add more fat cells if they become obese). The thematic review of Saini-Chohan et al. (33) on fatty acid metabolism is worth perusing by the reader for an illustration of the potential genomic disposition of the individual impacting the control of metabolism.
Lipopolysaccharides derived from gram-negative bacterial pool of human gut microbiota promote inflammation and obesity development
Published in International Reviews of Immunology, 2022
Liyu Du, Xi Lei, Jie Wang, Li Wang, Qingping Zhong, Xiang Fang, Pan Li, Bing Du, Yutao Wang, Zhenlin Liao
Obesity is characterized by the increased number and volume of adipocytes, accompanied by metabolic and inflammatory complications. Inflammation of adipose tissue in obese people has been the focus of recent studies on obesity and its related metabolic diseases. Adipose tissue was the first site where inflammation was found to be associated with obesity. Hotamisligil et al. [34]first found in vivo in animal models an abnormal increase in TNF-α expression by adipocytes in obese rats and mice. The main reason for this is the presence of LPS, which attracts macrophages to infiltrate into adipose tissue, causing an inflammatory immune response and the release of inflammatory factors (TNF-α, etc.). In some models, it was also found that high-fat diet-induced obesity and lipid accumulation cause high expression of inflammatory factors such as IL-1β, TNF-α, IL-6, intercellular adhesion molecule 1 (ICAM 1), and monocyte chemotactic protein-1 (MCP-1) [35–40].
Related Knowledge Centers
- Adipogenesis
- Brown Adipose Tissue
- Cell Culture
- Mesenchymal Stem Cell
- Osteoblast
- Cell
- Adipose Tissue
- Fat
- Muscle Cell
- White Adipose Tissue