BACKGROUND: Brown adipocytes have thermogenic characteristics in neonates and elicit anti-inflammatory responses. We postulated that thermogenic brown adipocytes produce distinctive intercellular effects in a hypobaric state. The purpose of this study is to analyze the correlation between brown adipocyte and regulatory T cell (T(reg)) expression under intermittent hypobaric conditions. METHODS: Brown and white adipocytes were harvested from the interscapular and flank areas of C57BL6 mice, respectively. Adipocytes were cultured with syngeneic splenocytes after isolation and differentiation. Intermittent hypobaric conditions were generated using cyclic negative pressure application for 48 h in both groups of adipocytes. Expression levels of T(regs) (CD4 + CD25 + Foxp3 + T cells), cytokines [tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10), and the programmed death-ligand 1 (PD-L1)] co-inhibitory ligand were examined. RESULTS: Splenocytes, cultured with brown and white adipocytes, exhibited comparable T(reg) expression in a normobaric state. Under hypobaric conditions, brown adipocytes maintained a subset of T(regs). However, a decrease in T(regs) was found in the white adipocyte group. TNF-α levels increased in both groups under hypobaric conditions. In the brown adipocyte group, anti-inflammatory IL-10 expression increased significantly; meanwhile, IL-10 expression decreased in the white adipocyte group. PD-L1 levels increased more significantly in brown adipocytes than in white adipocytes under hypobaric conditions. CONCLUSION: Both brown and white adipocytes support T(reg) expression when they are cultured with splenocytes. Of note, brown adipocytes maintained T(reg) expression in intermittent hypobaric conditions. Anti-inflammatory cytokines and co-inhibitory ligands mediate the immunomodulatory effects of brown adipocytes under altered atmospheric conditions. Brown adipocytes showed the feasibility as a source of adjustment in physical stresses.
Adipocytes ; Adipocytes, Brown ; Adipocytes, White ; Animals ; Coculture Techniques ; Cytokines ; Humans ; Infant, Newborn ; Interleukin-10 ; Ligands ; Mice ; Necrosis

Brown adipose tissue (BAT) is regarded as a key target for developing interventions to prevent and treat obesity and age-related diseases. In addition, uncoupling pro tein 1 (UCP1)
Adipocytes ; Adipose Tissue ; Adipose Tissue, Brown ; Adipose Tissue, White ; Atrophy ; Eating ; Humans ; Middle Aged ; Obesity ; Thermogenesis

The induction of brown-like adipocyte development in white adipose tissue (WAT) confers numerous metabolic benefits by decreasing adiposity and increasing energy expenditure. Therefore, WAT browning has gained considerable attention for its potential to reverse obesity and its associated co-morbidities. However, this perspective has been tainted by recent studies identifying the detrimental effects of inducing WAT browning. This review aims to highlight the adverse outcomes of both overactive and underactive browning activity, the harmful side effects of browning agents, as well as the molecular brake-switch system that has been proposed to regulate this process. Developing novel strategies that both sustain the metabolic improvements of WAT browning and attenuate the related adverse side effects is therefore essential for unlocking the therapeutic potential of browning agents in the treatment of metabolic diseases.
Adipocytes, Beige ; cytology ; Adipose Tissue, Brown ; cytology ; metabolism ; Adipose Tissue, White ; cytology ; Aging ; metabolism ; Animals ; Humans

OBJECTIVE: To establish a simple, low-cost and time-saving method for primary culture of mature white adipocytes from mice. METHODS: Mature white adipocytes were isolated from the epididymis and perirenal area of mice for primary culture using a modified mature adipocyte culture method or the ceiling culture method. The morphology of the cultured mature adipocytes was observed using Oil Red O staining, and the cell viability was assessed with CCK8 method. The expression of PPARγ protein in the cells was detected with Western blotting, and the mRNA expressions of CD36, FAS, CPT1A and FABP4 were detected using RT-qPCR. RESULTS: Oil Red O staining showed a good and uniform morphology of the adipocytes in primary culture using the modified culture method, while the cells cultured using the ceiling culture method exhibited obvious morphological changes. CCK8 assay showed no significant difference in cell viability between freshly isolated mature white adipocytes and the cells obtained with the modified culture method. Western blotting showed that the freshly isolated adipocytes and the cells cultured for 72 h did not differ significantly in the expression levels of PPARγ protein (P=0.759), which was significantly lowered in response to treatment with GW9662 (P < 0.001). GW9662 treatment of the cells upregulated mRNA expressions of CD36 (P < 0.001) and CPT1A (P=0.003) and down-regulated those of FAS (P=0.001) and FABP4 (P < 0.001). CONCLUSION We established a convenient and time-saving method for primary culture mature white adipocytes from mice to facilitate further functional studies of mature adipocytes.
Male ; Mice ; Animals ; Adipocytes, White/metabolism* ; PPAR gamma/metabolism* ; RNA, Messenger ; Cell Differentiation ; 3T3-L1 Cells

Adipose tissue inflammation is considered a major contributing factor in the development of obesity-associated insulin resistance and cardiovascular diseases. However, the cause of adipose tissue inflammation is presently unclear. The role of mitochondria in white adipocytes has long been neglected because of their low abundance. However, recent evidence suggests that mitochondria are essential for maintaining metabolic homeostasis in white adipocytes. In a series of recent studies, we found that mitochondrial function in white adipocytes is essential to the synthesis of adiponectin, which is the most abundant adipokine synthesized from adipocytes, with many favorable effects on metabolism, including improvement of insulin sensitivity and reduction of atherosclerotic processes and systemic inflammation. From these results, we propose a new hypothesis that mitochondrial dysfunction in adipocytes is a primary cause of adipose tissue inflammation and compared this hypothesis with a prevailing concept that “adipose tissue hypoxia” may underlie adipose tissue dysfunction in obesity. Recent studies have emphasized the role of the mitochondrial quality control mechanism in maintaining mitochondrial function. Future studies are warranted to test whether an inadequate mitochondrial quality control mechanism is responsible for mitochondrial dysfunction in adipocytes and adipose tissue inflammation.
11-beta-Hydroxysteroid Dehydrogenases ; Adipocytes ; Adipocytes, White ; Adipokines ; Adiponectin ; Adipose Tissue ; Anoxia ; Cardiovascular Diseases ; Homeostasis ; Inflammation ; Insulin Resistance ; Metabolism ; Mitochondria ; Nitric Oxide ; Obesity ; Quality Control

Brown adipose generates heat via oxidation of fatty acids by a mitochondrial uncoupling protein 1 (UCP1)-dependent process. In addition, a subpopulation of cells within subcutaneous white adipose tissue, known as beige adipocytes, also plays a role in thermogenesis. The biogenesis of beige adipocytes is induced by thermogenic signals, such as chronic cold exposure. Recently, it has been reported that eosinophils, type 2 cytokines of IL-4/13, and alternatively activated macrophages control the thermogenic cycle of beige adipocytes. Alternatively, activated macrophages induce UCP1+ beige adipocytes through secretion of catecholamines. These results define the role of type 2 immune responses in the regulation of energy homeostasis.
Adipocytes ; Adipose Tissue, Brown ; Adipose Tissue, White ; Organelle Biogenesis* ; Catecholamines ; Cytokines ; Eosinophils* ; Fatty Acids ; Homeostasis ; Hot Temperature ; Macrophages* ; Thermogenesis

OBJECTIVE: To investigate the time-sequential expression of a novel long non-coding RNA, lnc AK079912, in metabolically related tissues and during adipose tissue development and browning in mice. METHODS: The interscapular brown adipose tissue (iBAT), subcutaneous white adipose tissue (sWAT), epididymal white adipose tissue (eWAT), liver tissues and muscular tissues were collected from 8-week-old C57BL/6J mice. The iBAT, sWAT and eWAT were also collected from the mice during development (0 day, 21 days, 8 weeks and 6 months after birth) and from 8- to 10-week- mice with cold exposure (4 ℃) and intraperitoneal injections of CL316, 243 (1 μg/g body weight) for 1 to 5 days. Trizol was used to extract the total RNA from the tissues, and RT-qPCR was performed to detect the expressions of lnc AK079912. Isolated mouse preadipocytes in primary culture were induced for adipogenic differentiation for 9 days and then treated with CL316, 243 (2 μmol/L) for different durations (no longer than 24 h); the expression of lnc AK079912 in the cells was detected using RT-qPCR at different time points of the treatment. RESULTS: Lnc AK079912 was highly expressed in mouse adipose tissues, the highest in iBAT, followed by the muscular tissue, but was hardly detected in the liver tissue. The expression level of lnc AK079912 increased progressively in iBAT and sWAT during development of the mice, while its expression in eWAT showed an initial increase followed by a reduction at 8 weeks ( < 0.001). No significant difference was found in the expression of lnc AK079912 in the iBAT, sWAT or eWAT in mice with cold stimulation for 1 to 5 days ( > 0.05). The expression of lnc AK079912 was significantly decreased in iBAT and eWAT ( < 0.05) but increased in eWAT from mice with intraperitoneal injection of CL316, 243 for 1 to 5 days ( < 0.05). The expression level in the adipocytes in primary culture was significantly increased in response to treatment with CL316, 243 ( < 0.05). CONCLUSIONS Lnc AK079912 is highly expressed in mouse adipose tissue, and its expression gradually increases with the development of adipose tissue but with a depot-specific difference. Lnc AK079912 is significantly elevated in the early stage of adipose tissue browning, indicating its important role in the development and browning of adipose tissue.
Adipocytes ; Adipogenesis ; Adipose Tissue, Brown ; Adipose Tissue, White ; Animals ; Male ; Mice ; Mice, Inbred C57BL ; RNA, Long Noncoding

Adipose tissue is a central metabolic organ that controls energy homeostasis of the whole body. White adipose tissue (WAT) stores excess energy in the form of triglycerides, whereas brown adipose tissue (BAT) dissipates energy in the form of heat through mitochondrial uncoupling protein 1 (Ucp1). A newly identified adipose tissue called ‘beige fat’ (BAT-like) is produced through a process called WAT browning. This tissue mainly resides in WAT depots and displays intermediate characteristics of both WAT and BAT. Since the recent discovery of BAT in the human body, along with the identification of molecular targets for BAT activation, stimulating energy expenditure has been considered as a great strategy to treat human obesity and metabolic diseases. Here we summarize recent findings regarding molecular targets and thermogenic small molecules that can stimulate BAT and increase energy expenditure, with an emphasis on possible therapeutic applications in humans.
Adipocytes* ; Adipose Tissue ; Adipose Tissue, Brown ; Adipose Tissue, White ; Energy Metabolism ; Homeostasis ; Hot Temperature ; Human Body ; Humans ; Metabolic Diseases ; Obesity ; Triglycerides

Leptin is a 16 kDa protein which consists of 167 amino acids. Leptin is considered as one of the adipokines, secreted by white adipocytes, and is the product of the obese (ob) gene. Recently, leptin is recognized as the immuno-stimulator which belongs to the same class of long chain helical cytokines such as interleukin (IL)-6. Leptin is related to the immune responses evoked by Mycobacterium tuberculosis infection. Thus, studies of association between immunomolecules including leptin and tuberculosis may contribute to provide an essential solution regulating adverse immune responses in several mycobacterial diseases. Leptin has a multifunctional role in the secretion of acute-phase cytokines including IL-1beta and tumor-necrosis factor-alpha (TNF-alpha), and links to T helper 1 (Th1) immune response. Moreover, the binding of leptin to leptin receptor (LepR) is important in that this binding involves janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. In addition, the activation of LepR mediates extra-cellular signal-regulated kinase (ERK) and phosphoinositide 3 kinase (PI3K) pathways. Furthermore, many studies suggest that leptin may play a critical role in respiratory diseases including chronic obstructive pulmonary disease (COPD) and asthma as well as tuberculosis. These findings indicate that leptin is one of the important regulators for immune responses in respiratory diseases. We herein discuss the multifunctional role of leptin in mycobacterial lung disease, especially focusing on the related pathway to immune responses.
Adipocytes, White ; Adipokines ; Amino Acids ; Asthma ; Cytokines ; Interleukins ; Leptin ; Lung ; Lung Diseases ; Mycobacterium tuberculosis ; Phosphotransferases ; Pulmonary Disease, Chronic Obstructive ; Receptors, Leptin ; Signal Transduction ; Transducers ; Tuberculosis

Given that increased thermogenesis in white adipose tissue, also known as browning, promotes energy expenditure, significant efforts have been invested to determine the molecular factors involved in this process. Here we show that HOXC10, a homeobox domain-containing transcription factor expressed in subcutaneous white adipose tissue, is a suppressor of genes involved in browning white adipose tissue. Ectopic expression of HOXC10 in adipocytes suppresses brown fat genes, whereas the depletion of HOXC10 in adipocytes and myoblasts increases the expression of brown fat genes. The protein level of HOXC10 inversely correlates with brown fat genes in subcutaneous white adipose tissue of cold-exposed mice. Expression of HOXC10 in mice suppresses cold-induced browning in subcutaneous white adipose tissue and abolishes the beneficial effect of cold exposure on glucose clearance. HOXC10 exerts its effect, at least in part, by suppressing PRDM16 expression. The results support that HOXC10 is a key negative regulator of the process of browning in white adipose tissue.
Adipocytes ; Adipose Tissue, Brown ; Adipose Tissue, White ; Animals ; Ectopic Gene Expression ; Energy Metabolism ; Genes, Homeobox ; Glucose ; Mice ; Myoblasts ; Thermogenesis ; Transcription Factors