• Journal of Life Science
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• v.33 no.3
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• pp.287-294
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• 2023

Healthy adipose tissue is critical for preventing obesity by maintaining metabolic homeostasis. Adipose tissue plays an important role in energy homeostasis through glucose and lipid metabolism. Depending on nutritional status, adipose tissue expands to store lipids or can be consumed by lipolysis. The role of adipose tissue as an endocrine organ is emerging, and many studies have reported that there are various adipose tissue hormones that communicate with other organs and tissues through metabolic signaling. For example, leptin, a representative peptide hormone secreted from adipose tissues (adipokine), circulates and targets the central nervous system of the brain for appetite regression. Furthermore, adipocytes secrete inflammatory cytokines to target immune cells in adipose tissues. Not surprisingly, adipocytes can secrete fatty acid-derived hormones (lipokine) that bind to their specific receptors for paracrine and endocrine action. To understand organ crosstalk by adipose tissue hor- mones, specific metabolic signaling in adipocytes and other communicating cells should be defined. The dysfunction of metabolic signaling in adipocytes occurs in unhealthy adipose tissue in overweight and obese conditions. Therapy targeting novel adipose metabolic signaling could potentially lead to the development of an effective anti-obesity drug. This review summarizes the latest updates on adipose tissue hormone and metabolic signaling in terms of obesity and metabolic diseases.

• Journal of Korean Medicine for Obesity Research
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• v.7 no.2
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• pp.15-25
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• 2007

Objectives In clinical studies, the visceral fat obesity has been emphasized because of its correlation with the metabolic syndrome. But the subcutaneous adipose tissue also would correlate with the risk factor of metabolic syndrome. Especially deep tissue, which is a subdivision of the subcutaneous adipose tissue would be more related. This study is to investigate the relationship between subcutaneous adipose tissue and various diseases. Methods We searched for papers which had subcutaneous adipose tissue, deep subcutaneous adipose tissue and obesity for subjects in the Pubmed site. Results : 24 papers were found. Subcutaneous adipose tissue, deep subcutaneous adipose tissue especially, was related with the insulin resistance, metabolic syndrome, sex hormones and other diseases. Conclusions Subcutaneous adipose tissue is a risk factor of insulin resistance but not lipoprotein. But deep subcutaneous adipose tissue was related with lipoprotein. So deep tissue, which is a subdivision of the subcutaneous adipose tissue is a more important risk factor of the metabolic syndrome.

• Journal of Magnetics
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• v.21 no.4
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• pp.603-615
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• 2016

In this study, in order to determine the validity and accuracy of MR imaging of 3D gradient dual echo 2-point DIXON technique for measuring abdominal adipose tissue volume and distribution, the measurements obtained by CT were set as a reference for comparison and their correlations were evaluated. CT and MRI scans were performed on each subject (17 healthy male volunteers who were fully informed about this study) to measure abdominal adipose tissue volume. Two skilled investigators individually observed the images acquired by CT and MRI in an independent environment, and directly separated the total volume using region-based thresholding segmentation method, and based on this, the total adipose tissue volume, subcutaneous adipose tissue volume and visceral adipose tissue volume were respectively measured. The correlation of the adipose tissue volume measurements with respect to the observer was examined using the Spearman test and the inter-observer agreement was evaluated using the intra-class correlation test. The correlation of the adipose tissue volume measurements by CT and MRI imaging methods was examined by simple regression analysis. In addition, using the Bland-Altman plot, the degree of agreement between the two imaging methods was evaluated. All of the statistical analysis results showed highly statistically significant correlation (p<0.05) respectively from the results of each adipose tissue volume measurements. In conclusion, MR abdominal adipose volumetry using the technique of 3D gradient dual echo 2-point DIXON showed a very high level of concordance even when compared with the adipose tissue measuring method using CT as reference.

• Development and Reproduction
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• v.20 no.3
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• pp.197-205
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• 2016

Adipose tissue is one of the major endocrine gland. More recently, local production of steroids in adipocytes differentiated from mouse 3T3-L1 cell-line was reported. We hypothesized that rat adipocytes have steroidogenic machinery and the expression patterns of the components might be differentially regulated, depending on the distribution and sex. To verify this hypothesis, we collected the adipose tissues depot-and sex-specifically at postnatal day (PND) 30, and performed quantitative RT-PCRs. In overall aspects, the abundances of the transcripts were lower in the brown adipose of both sexes. $3{\beta}-HSD$ transcript levels in female abdominal and reproductive adipose, CYP17 transcript levels in female reproductive adipose, $17{\beta}-HSD$ transcript levels in female abdominal and reproductive adipose, and CYP19 transcript levels in female abdominal adipose were significantly lower than those of male counterparts. Similar to steroidogenic factors, the abundance of the $ER-{\alpha}$ transcripts were generally lower in the brown adipose of both sexes. $ER-{\beta}$ transcripts were more abundant in male white adipose depots than their female counterparts. The levels of LHR transcripts in female reproductive adipose were significantly higher than those of male counterpart. In conclusion, our study demonstrated that the expressions of steroidogenesis-related genes were depot- and sex-specifically occurred in the immature male and female rat adipose tissues. Our study suggested that the adipose tissues are not only targets but de novo synthesizing sites of sex steroid(s), though the synthesizing activities could be much less than in gonads. Further researches in this field will be helpful for understanding the adipose physiology and for medical application such as sex-specific steroid supplement therapies for older populations.

• Journal of Life Science
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• v.32 no.4
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• pp.318-324
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• 2022

PPARγ and C/EBPα are master adipogenic transcription factors (TFs) required for adipose tissue development. They control the induction of many adipocyte genes and the early phase of adipogenesis in the embryonic development of adipose tissue. Adipose tissue continues to expand after birth, which, as a late phase of adipogenesis, requires the lipogenesis of adipocytes. In particular, the liver and adipose tissues are major sites for de novo lipogenesis (DNL), where carbohydrates are primarily converted to fatty acids. Furthermore, fatty acids are esterified with glycerol-3-phosphate to produce triglyceride, a major source of lipid droplets in adipocytes. Hepatic DNL has been actively studied, but the DNL of adipocytes in vivo remains not fully understood. Thus, an understanding of lipogenesis and adipose expansion may provide therapeutic opportunities for obesity, type 2 diabetes, and metabolic diseases. In adipocytes, DNL gene expression is transcriptionally regulated by lipogenesis coactivators, as well as by lipogenic TFs such as ChREBP and SREBP1a. Recent in vivo studies have revealed new insights into the lipogenesis gene expression and adipose expansion. Future detailed molecular mechanism studies will determine how nutrients and metabolism regulate DNL and adipose expansion. This review will summarize recent updates of DNL in adipocytes and adipose expansion in terms of transcriptional regulation.

• Archives of Plastic Surgery
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• v.35 no.6
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• pp.653-658
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• 2008

Purpose: Skin and soft tissue defect is one of the major challenges faced by plastic surgeons. Adipose derived stromal cells, which can be harvested in large quantities with low morbidity, display multilineage mesodermal potential. Therefore, adipose derived stromal cells have been met with a great deal of excitement by the field of tissue engineering. Recently, Adipose derived stromal cells have been isolated and cultured to use soft tissue restoration. In order to apply cultured cells for clinical purpose, however, FDA approved facilities and techniques are required, which may be difficult for a clinician who cultures cells in a laboratory dedicated to research to utilize this treatment for patients. In addition, long culture period is needed. Fortunately, adipose derived stromal cells are easy to obtain in large quantities without cell culture. The purpose of this study is to present a possibility of using uncultured adipose derived stromal cells for wound coverage. Methods: Seven patients who needed skin and soft tissue restoration were included. Five patients had diabetic foot ulcers, 1 patient got thumb amputation, and 1 patient had tissue defect caused by resection of squamous cell carcinoma. The patients' abdominal adipose tissues were obtained by liposuction. The samples were digested with type I collagenase and centrifuged to obtain adipose derived stromal cells. The isolated adipose derived stromal cells were applied over the wounds immediately after the wound debridement. Fibrin was used as adipose derived stromal cells carrier. Occlusive dressing was applied with films and foams and the wounds were kept moist until complete healing. Results: One hundred to one hundred sixty thousand adipose derived stromal cells were isolated per ml aspirated adipose tissue. All patients' wounds were successfully covered with the grafted adipose derived stromal cells in a 17 to 27 day period. No adverse events related to this treatment occurred. Conclusion: The use of uncultured adipose derived stromal cells was found to be safe and effective treatment for wound coverage without donor site morbidity.

• Nutrition Research and Practice
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• v.14 no.6
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• pp.553-567
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• 2020

Vitamin D insufficiency is associated with obesity and its related metabolic diseases. Adipose tissues store and metabolize vitamin D and expression levels of vitamin D metabolizing enzymes are known to be altered in obesity. Sequestration of vitamin D in large amount of adipose tissues and low vitamin D metabolism may contribute to the vitamin D inadequacy in obesity. Vitamin D receptor is expressed in adipose tissues and vitamin D regulates multiple aspects of adipose biology including adipogenesis as well as metabolic and endocrine function of adipose tissues that can contribute to the high risk of metabolic diseases in vitamin D insufficiency. We will review current understanding of vitamin D regulation of adipose biology focusing on vitamin D modulation of adiposity and adipose tissue functions as well as the molecular mechanisms through which vitamin D regulates adipose biology. The effects of supplementation or maintenance of vitamin D on obesity and metabolic diseases are also discussed.

• Molecules and Cells
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• v.37 no.5
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• pp.365-371
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• 2014

Recent findings, notably on adipokines and adipose tissue inflammation, have revised the concept of adipose tissues being a mere storage depot for body energy. Instead, adipose tissues are emerging as endocrine and immunologically active organs with multiple effects on the regulation of systemic energy homeostasis. Notably, compared with other metabolic organs such as liver and muscle, various inflammatory responses are dynamically regulated in adipose tissues and most of the immune cells in adipose tissues are involved in obesity-mediated metabolic complications, including insulin resistance. Here, we summarize recent findings on the key roles of innate (neutrophils, macrophages, mast cells, eosinophils) and adaptive (regulatory T cells, type 1 helper T cells, CD8 T cells, B cells) immune cells in adipose tissue inflammation and metabolic dysregulation in obesity. In particular, the roles of natural killer T cells, one type of innate lymphocyte, in adipose tissue inflammation will be discussed. Finally, a new role of adipocytes as antigen presenting cells to modulate T cell activity and subsequent adipose tissue inflammation will be proposed.

• Molecules and Cells
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• v.47 no.2
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• pp.100030.1-100030.14
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• 2024

Both brown and white adipose tissues (BAT/WAT) are innervated by the peripheral nervous system, including efferent sympathetic nerves that communicate from the brain/central nervous system out to the tissue, and afferent sensory nerves that communicate from the tissue back to the brain and locally release neuropeptides to the tissue upon stimulation. This bidirectional neural communication is important for energy balance and metabolic control, as well as maintaining adipose tissue health through processes like browning (development of metabolically healthy brown adipocytes in WAT), thermogenesis, lipolysis, and adipogenesis. Decades of sensory nerve denervation studies have demonstrated the particular importance of adipose sensory nerves for brown adipose tissue and WAT functions, but far less is known about the tissue's sensory innervation compared to the better-studied sympathetic nerves and their neurotransmitter norepinephrine. In this review, we cover what is known and not yet known about sensory nerve activities in adipose, focusing on their effector neuropeptide actions in the tissue.

• IMMUNE NETWORK
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• v.6 no.4
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• pp.169-178
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• 2006

Background: Adipose tissues were initially introduced as energy storages, but recently they have become famous as an endocrine organ which produces and secretes various kinds of molecules to make physiologic and metabolic changes in human body. It has been studied that these molecules are secreted in abundance as the adipose tissue becomes bigger along with obesity. Furthermore, it has been found that they are mediating systemic inflammation and generation of metabolic diseases such as type 2 diabetes and atherosclerosis. On the basis of these, we studied previous papers which have been researched about the interaction between preadipocytes and macrophages, adipose tissues and lymph nodes, and adipose tissue secreting molecules. Results: Firstly, preadipocytes and macrophages are expressing similar transcriptomes and proteins, and preadipocytes can be converted to mature macrophages which have phagocytic activity. Moreover, the monocytes, which initially located in the bone marrow, are filtrated to the adipose tissue by monocyte chemotatic protein-1 and are matured to macrophages by colony stimulating factor-1. Secondly, adipose tissues and their associated lymph nodes are interacting each other in terms of energy efficiency. Lymph nodes promote lipolysis in adipose tissues, and polyunsaturated fatty acids in adipocytes become energy sources for dendritic cells. Lastly, adipose tissues produce and secrete proinflammatory molecules such as leptin, adiponectin, TNF-${\alpha}$, IL-6, and acute phase proteins, which induce the inflammation and potentially generate metabolic diseases. Conclusion: According to these, we can link adipose tissues to inflammation, but we need to affirm the actual levels and roles of adipose tissue-derived proinflammatory molecules in human body.