Characteristics Of Adipocytes Research Articles

Inflammatory Cells in Adipose Tissue and Skeletal Muscle of Patients with Peripheral Arterial Disease or Chronic Venous Disease: A Prospective, Observational, and Histological Study.

The main goal of this study was to assess whether the presence of peripheral arterial disease (PAD) correlates with increased inflammatory cell infiltration. An observational, single-centre, and prospective study was conducted from January 2018 to July 2022. Clinical characteristics and anthropometric measures were registered. Consecutive PAD patients with surgical indications for a common femoral artery approach and patients with varicose veins with an indication for surgical ligation of the saphenofemoral junction were included. In both groups, samples of sartorius skeletal muscle, subcutaneous adipose tissue (SAT), and perivascular adipose tissue (PVAT) were collected from the femoral region. We analysed the characteristics of adipocytes and the presence of haemorrhage and inflammatory cells in the samples of PVAT and SAT via haematoxylin-eosin staining. We found that patients with PAD had significantly more inflammatory cells in PVAT [16 (43.24%) vs. 0 (0%) p = 0.008]. Analysing SAT histology, we observed that patients with PAD had significantly more CD45+ leucocytes upon immunohistochemical staining [32 (72.73%) vs. 3 (27.27%) p = 0.005]. Upon analysing skeletal muscle histology with haematoxylin-eosin staining, we evaluated skeletal fibre preservation, as well as the presence of trauma, haemorrhage, and inflammatory cells. We registered a significantly higher number of inflammatory cells in patients with PAD [well-preserved skeletal fibres: PAD = 26 (63.41%) vs. varicose veins = 3 (37.50%) p = 0.173; trauma: PAD = 4 (9.76%) vs. varicose veins = 2 (25.00%) p = 0.229; haemorrhage: PAD = 6 (14.63%) vs. varicose veins = 0 (0%) p = 0.248; inflammatory cells: PAD = 18 (43.90%) vs. varicose veins = 0 (0%) p = 0.018]. Patients with PAD had a higher number of inflammatory cells in skeletal muscle and adipose tissue (PVAT and SAT) when compared with those with varicose veins, emphasizing the role of inflammation in this group of patients.

Molecular and cellular regulation of thermogenic fat.

Thermogenic fat, consisting of brown and beige adipocytes, dissipates energy in the form of heat, in contrast to the characteristics of white adipocytes that store energy. Increasing energy expenditure by activating brown adipocytes or inducing beige adipocytes is a potential therapeutic strategy for treating obesity and type 2 diabetes. Thus, a better understanding of the underlying mechanisms of thermogenesis provides novel therapeutic interventions for metabolic diseases. In this review, we summarize the recent advances in the molecular regulation of thermogenesis, focusing on transcription factors, epigenetic regulators, metabolites, and non-coding RNAs. We further discuss the intercellular and inter-organ crosstalk that regulate thermogenesis, considering the heterogeneity and complex tissue microenvironment of thermogenic fat.

Cucurbitacin B-, E-, and I-Induced Browning of White Adipocytes Is Promoted by the Inhibition of Phospholipase D2.

The mechanism of white adipose tissue browning is not well understood; however, naturally occurring compounds are known to play a positive role. The effects of cucurbitacins B, E, and I on the browning of mature white adipocytes were investigated. First, the cell viability exhibited by cucurbitacins B, E, and I in pre- and mature adipocytes was verified. Cucurbitacins B, E, and I had no effect on cell viability in pre- and mature adipocytes at concentrations up to 300 nM. To investigate the characteristics of representative beige adipocytes, the formation and morphology of cucurbitacin B, E, and I lipid droplets were verified. The total lipid droplet surface area, maximum Feret diameter, and total Nile red staining intensity of cucurbitacin B-, E-, and I-treated adipocytes were lower than those of mature white adipocytes. Furthermore, treatment of white mature adipocytes with cucurbitacin B, E, and I led to the formation of several small lipid droplets that are readily available for energy expenditure. We evaluated the effect of cucurbitacins B, E, and I on the expression of representative browning markers UCP1, PGC1a, and PRDM16, which participate in the browning of white adipose tissue. Cucurbitacins B, E, and I increased the mRNA and protein expression levels of UCP1, PGC1a, and PRDM16 in a concentration-dependent manner. To promote energy consumption by beige adipocytes, active mitochondrial biogenesis is essential. Next, we investigated the effects of cucurbitacin B, E, and I on mitochondrial biogenesis in mature adipocytes. Mitochondrial mass increased when mature adipocytes were treated with cucurbitacin B, E, and I. The degree of cucurbitacin B-, E- and I-induced transformation of white adipocytes into beige adipocytes was in the order of Cu E > Cu B > Cu I. To verify the effect of phospholipase D2 on the browning of white adipocytes, CAY10594—a PLD2 pharmacological inhibitor, and a knockdown system were used. PLD2 inhibition and knockdown improved the expression levels of UCP1, PGC1a, and PRDM16. In addition, PLD2 inhibition and knockdown in mature white adipocytes promoted mitochondrial biosynthesis. The effect of PLD2 inhibition and knockdown on promoting browning of white adipocytes significantly increased when Cu B, Cu E, and Cu I were co-treated. These data indicate that mature white adipocytes’ beige properties were induced by cucurbitacins B, E, and I. These effects became more potent by the inhibition of PLD2. These findings provide a model for determining anti-obesity agents that induce browning and increase energy expenditure in mature white adipocytes.

ApoA1 Deficiency Reshapes the Phenotypic and Molecular Characteristics of Bone Marrow Adipocytes in Mice.

In the present study, we studied the effect of apolipoprotein A-1 (APOA1) on the spatial and molecular characteristics of bone marrow adipocytes, using well-characterized ApoA1 knockout mice. APOA1 is a central regulator of high-density lipoprotein cholesterol (HDL-C) metabolism, and thus HDL; our recent work showed that deficiency of APOA1 increases bone marrow adiposity in mice. We found that ApoA1 deficient mice have greatly elevated adipocytes within their bone marrow compared to wild type counterparts. Morphologically, the increased adipocytes were similar to white adipocytes, and displayed proximal tibial-end localization. Marrow adipocytes from wild type mice were significantly fewer and did not display a bone-end distribution pattern. The mRNA levels of the brown/beige adipocyte-specific markers Ucp1, Dio2, Pat2, and Pgc1a; and the expression of leptin were greatly reduced in the ApoA1 knock-out in comparison to the wild-type mice. In the knock-out mice, adiponectin was remarkably elevated. In keeping with the close ties of hematopoietic stem cells and marrow adipocytes, using flow cytometry we found that the elevated adiposity in the ApoA1 knockout mice is associated with a significant reduction in the compartments of hematopoietic stem cells and common myeloid, but not of the common lymphoid, progenitors. Moreover, the ‘beiging’-related marker osteopontin and the angiogenic factor VEGF were also reduced in the ApoA1 knock-out mice, further supporting the notion that APOA1—and most probably HDL-C—regulate bone marrow microenvironment, favoring beige/brown adipocyte characteristics.

Identification of Biochemical Differences in White and Brown Adipocytes Using FTIR Spectroscopy

This study was conducted to investigate the developmental characteristics of adipocytes and to identify selectively white and brown adipocytes through Fourier transform infrared (FTIR) spectroscopy. For the developmental characterization of adipocytes, cells and conditioned media of white and brown adipocytes were respectively collected and analyzed. A higher amide I/amide II ratio was observed in the conditioned medium of brown adipocyte than in that of white adipocyte, indicating differences in secretory protein profiles. In contrast, an amide I/amide II ratio was higher in white adipocytes than in brown adipocytes, and mature adipocytes have higher lipid amounts than pre-adipocytes. Lipid acyl chain length was the longest in white adipocytes. These differences suggested that FTIR spectroscopy can be used to characterize developmental stages and/or types of adipocytes. To identify the possibility of selectively classifying adipose-derived stem cells, FTIR spectroscopy spectra were obtained in cells before/after white/brown adipocyte differentiation using FTIR spectroscopy and then analyzed by the principal component analysis method. All data indicated that the discrimination between adipocytes was possible in the analysis of the infrared spectroscopy spectrum by the principal component analysis technique. This study suggested the possibility of FTIR spectroscopy as a new type of cell sorting system without tagging.

Mouse model of the adipose organ: the heterogeneous anatomical characteristics.

Adipose tissue plays a pivotal role in energy storage, hormone secretion, and temperature control. Mammalian adipose tissue is largely divided into white adipose tissue and brown adipose tissue, although recent studies have discovered the existence of beige adipocytes. Adipose tissues are widespread over the whole body and each location shows distinctive metabolic features. Mice are used as a representative experimental model system in metabolic studies due to their numerous advantages. Importantly, the adipose tissues of experimental animals and humans are not perfectly matched, and each adipose tissue exhibits both similar and specific characteristics. Nevertheless, the diversity and characteristics of mouse adipose tissue have not yet been comprehensively summarized. This review summarizes diverse information about the different types of adipose tissue being studied in mouse models. The types and characteristics of adipocytes were described, and each adipose tissue was classified by type, and features such as its distribution, origin, differences from humans, and metabolic characteristics were described. In particular, the distribution of widely studied adipose tissues was illustrated so that researchers can comprehensively grasp its location. Also, the adipose tissues misused or confusingly used among researchers were described. This review will provide researchers with comprehensive information and cautions needed to study adipose tissues in mouse models.

A Data-Driven Transcriptional Taxonomy of Adipogenic Chemicals to Identify White and Brite Adipogens.

Background:Chemicals in disparate structural classes activate specific subsets of the transcriptional programs of peroxisome proliferator-activated receptor- () to generate adipocytes with distinct phenotypes.Objectives:Our objectives were to a) establish a novel classification method to predict ligands and modifying chemicals; and b) create a taxonomy to group chemicals on the basis of their effects on transcriptome and downstream metabolic functions. We tested the hypothesis that environmental adipogens highly ranked by the taxonomy, but segregated from therapeutic ligands, would induce white but not brite adipogenesis.Methods:3T3-L1 cells were differentiated in the presence of 76 chemicals (negative controls, nuclear receptor ligands known to influence adipocyte biology, potential environmental ligands). Differentiation was assessed by measuring lipid accumulation. mRNA expression was determined by RNA-sequencing (RNA-Seq) and validated by reverse transcription–quantitative polymerase chain reaction. A novel classification model was developed using an amended random forest procedure. A subset of environmental contaminants identified as strong agonists were analyzed by their effects on lipid handling, mitochondrial biogenesis, and cellular respiration in 3T3-L1 cells and human preadipocytes.Results:We used lipid accumulation and RNA-Seq data to develop a classification system that a) identified agonists; and b) sorted chemicals into likely white or brite adipogens. Expression of Cidec was the most efficacious indicator of strong activation. 3T3-L1 cells treated with two known environmental ligands, tetrabromobisphenol A and triphenyl phosphate, which sorted distinctly from therapeutic ligands, had higher expression of white adipocyte genes but no difference in Pgc1a and Ucp1 expression, and higher fatty acid uptake but not mitochondrial biogenesis. Moreover, cells treated with two chemicals identified as highly ranked agonists, tonalide and quinoxyfen, induced white adipogenesis without the concomitant health-promoting characteristics of brite adipocytes in mouse and human preadipocytes.Discussion:A novel classification procedure accurately identified environmental chemicals as ligands distinct from known -activating therapeutics.Conclusion:The computational and experimental framework has general applicability to the classification of as-yet uncharacterized chemicals. https://doi.org/10.1289/EHP6886

Dental-Derived Mesenchymal Stem Cells: State of the Art.

Mesenchymal stem cells (MSCs) could be identified in mammalian teeth. Currently, dental-derived MSCs (DMSCs) has become a collective term for all the MSCs isolated from dental pulp, periodontal ligament, dental follicle, apical papilla, and even gingiva. These DMSCs possess similar multipotent potential as bone marrow-derived MSCs, including differentiation into cells that have the characteristics of odontoblasts, cementoblasts, osteoblasts, chondrocytes, myocytes, epithelial cells, neural cells, hepatocytes, and adipocytes. Besides, DMSCs also have powerful immunomodulatory functions, which enable them to orchestrate the surrounding immune microenvironment. These properties enable DMSCs to have a promising approach in injury repair, tissue regeneration, and treatment of various diseases. This review outlines the most recent advances in DMSCs’ functions and applications and enlightens how these advances are paving the path for DMSC-based therapies.

Pyruvate Kinase M2 Deficiency Enhances Brown Fat Adipogenesis and Activity

In the last decade, development and regulation of brown adipose tissue (BAT) has gained traction due to its potential role in the protection against obesity and its associated disorders. Notably, BAT activity inversely correlates with overall adiposity. Brown fat-like adipocytes, that express the brown adipocyte-specific uncoupling protein 1, are interspersed in WAT of rodents and humans. These brown-like adipocytes exhibit many of the morphological and biochemical characteristics of classical brown adipocytes. Remarkably, brown-like transformation of WAT is associated with resistance to diet induced obesity in experimental mouse models. However, the mechanisms that regulate the browning of WAT remain incompletely understood. Recent studies have shown that inhibition of the glycolytic enzyme Pyruvate Kinase M2 (PKM2) promotes brown adipogenesis. Notably, PKM2 is an upstream regulator of the Wnt/β-catenin. Although the molecular mechanisms are yet to be determined, recent studies have shown that the Wnt/β-catenin regulates the differentiation of both, white and brown adipogenesis. Therefore, the main objective of the current study is to investigate the role of Wnt/β-catenin in mediating PKM2’s function in in brown adipogenesis and function. We demonstrate that PKM2 deficiency and pharmacological inhibition enhances brown fat activity via modulation of the Wnt/β-catenin signaling pathway. These findings identify PKM2 as a good target for therapeutic approaches aiming at overcoming the obesity epidemic and its comorbidities.

The thermogenic characteristics of adipocytes are dependent on the regulation of iron homeostasis

The development of thermogenic adipocytes concurs with mitochondrial biogenesis, an iron-dependent pathway. Iron regulatory proteins (IRP) 1 and 2 are RNA-binding proteins that regulate intracellular iron homeostasis. IRPs bind to the iron-response element (IRE) of their target mRNAs, balancing iron uptake and deposition at the posttranscriptional levels. However, IRP/IRE-dependent iron regulation in adipocytes is largely unknown. We hypothesized that iron demands are higher in brown/beige adipocytes than white adipocytes to maintain the thermogenic mitochondrial capacity. To test this hypothesis, we investigated the IRP/IRE regulatory system in different depots of adipose tissue. Our results revealed that 1) IRP/IRE interaction was increased in proportional to the thermogenic function of the adipose depot, 2) adipose iron content was increased in adipose tissue browning upon β3-adrenoceptor stimulation, while decreased in thermoneutral conditions, and 3) modulation of iron content was linked with mitochondrial biogenesis. Moreover, the iron requirement was higher in HIB1B brown adipocytes than 3T3-L1 white adipocytes during differentiation. The reduction of the labile iron pool (LIP) suppressed the differentiation of brown/beige adipocytes and mitochondrial biogenesis. Using the 59Fe-Tf, we also demonstrated that thermogenic stimuli triggered cell-autonomous iron uptake and mitochondrial compartmentalization as well as enhanced mitochondrial respiration. Collectively, our work demonstrated that IRP/IRE signaling and subsequent adaptation in iron metabolism are a critical determinant for the thermogenic function of adipocytes.

Pathophysiological justification of age- and gender-dependent morphological changes in the adipose tissue in rat models of metabolic syndrome

Introduction: The mechanisms of metabolic syndrome (MS) is one of the urgent issues in medicine. Regional distribution of the adipose tissue should be diagnosed at clinical examination, as the morphometric parameters of the cells of the active adipose tissue components may indicate the metabolic state. Aim: The aim of the study was to evaluate the differences in morphological and histological parameters of the adipose tissue associated with the development of MS in animals of different ages and gender. Material and methods: An experimental study was carried out on 144 WAG/G Sto white rats, divided into three study groups. Group 1 included young immature rats, 3 months old; group 2 consisted of 48 sexually mature rats, aged 5–6 months; group 3 consisted of 48 old rats, 18 months old. Each group was divided into 2 subgroups, control and experimental, and was additionally divided according to gender. Results and discussion: The body mass indices and specific weights of mesenteric, epididymal, retroperitoneal and subcutaneous adipose tissue were determined in rats, as well as morphological characteristics of adipocytes of the adipose tissue. It was shown that histological and morphological changes in the adipose tissue of the animals were age- and gender-dependent, and that obesity is associated with chronic inflammation of the adipose tissue. Conclusions: The results of the study can be used for further determination of possible age and gender differences in the adipose tissue involvement in the development of chronic inflammation, as well as monitoring and correction of adipose tissue dysfunction in MS.

Dysmetabolic adipose tissue in obesity: morphological and functional characteristics of adipose stem cells and mature adipocytes in healthy and unhealthy obese subjects.

The way by which subcutaneous adipose tissue (SAT) expands and undergoes remodeling by storing excess lipids through expansion of adipocytes (hypertrophy) or recruitment of new precursor cells (hyperplasia) impacts the risk of developing cardiometabolic and respiratory diseases. In unhealthy obese subjects, insulin resistance, type 2 diabetes, hypertension, and obstructive sleep apnoea are typically associated with pathologic SAT remodeling characterized by adipocyte hypertrophy, as well aschronic inflammation, hypoxia, increased visceral adipose tissue (VAT), and fatty liver. In contrast, metabolically healthy obese individuals are generally associated with SAT development characterized by the presence of smaller and numerous mature adipocytes, and a lower degree of VATinflammation and ectopic fat accumulation. The remodeling of SAT and VAT is under genetic regulation and influenced by inherent depot-specific differences of adipose tissue-derived stem cells (ASCs). ASCs have multiple functions such as cell renewal, adipogenic capacity, and angiogenic properties, and secrete a variety of bioactive molecules involved in vascular and extracellular matrix remodeling. Understanding the mechanisms regulating the proliferative and adipogenic capacity of ASCs from SAT and VAT in response to excess calorie intake has become a focus of interest over recent decades. Here, we summarize current knowledge about the biological mechanisms able to foster or impair the recruitment and adipogenic differentiation of ASCs during SAT and VAT development, which regulate body fat distribution and favorableor unfavorable metabolic responses.

Cold‐induced beigeing of stem cell‐derived adipocytes is not fully reversible after return to normothermia

Beige adipocytes possess the morphological and biochemical characteristics of brown adipocytes, including the mitochondrial uncoupling protein (UCP)1. Mesenchymal stem cells (MSCs) are somatic multipotent progenitors which differentiate into lipid‐laden adipocytes. Induction of MSC adipogenesis under hypothermic culture conditions (ie 32°C) promotes the appearance of a beige adipogenic phenotype, but the stability of this phenotypic switch after cells are returned to normothermic conditions of 37°C has not been fully examined. Here, cells transferred from 32°C to 37°C retained their multilocular beige‐like morphology and exhibited an intermediate gene expression profile, with both beige‐like and white adipocyte characteristics while maintaining UCP1 protein expression. Metabolic profile analysis indicated that the bioenergetic status of cells initially differentiated at 32°C adapted post‐transfer to 37°C, showing an increase in mitochondrial respiration and glycolysis. The ability of the transferred cells to respond under stress conditions (eg carbonyl cyanide‐4‐phenylhydrazone (FCCP) treatment) demonstrated higher functional capacity of enzymes involved in the electron transport chain and capability to supply substrate to the mitochondria. Overall, MSC‐derived adipocytes incubated at 32°C were able to remain metabolically active and retain brown‐like features after 3 weeks of acclimatization at 37°C, indicating these phenotypic characteristics acquired in response to environmental conditions are not fully reversible.

Molecular Mechanism of Stem Cell Differentiation into Adipocytes and Adipocyte Differentiation of Malignant Tumor.

Adipogenesis is the process through which preadipocytes differentiate into adipocytes. During this process, the preadipocytes cease to proliferate, begin to accumulate lipid droplets, and develop morphologic and biochemical characteristics of mature adipocytes. Mesenchymal stem cells (MSCs) are a type of adult stem cells known for their high plasticity and capacity to generate mesodermal and nonmesodermal tissues. Many mature cell types can be generated from MSCs, including adipocyte, osteocyte, and chondrocyte. The differentiation of stem cells into multiple mature phenotypes is at the basis for tissue regeneration and repair. Cancer stem cells (CSCs) play a very important role in tumor development and have the potential to differentiate into multiple cell lineages. Accumulating evidence has shown that cancer cells can be induced to differentiate into various benign cells, such as adipocytes, fibrocytes, osteoblast, by a variety of small molecular compounds, which may provide new strategies for cancer treatment. Recent studies have reported that tumor cells undergoing epithelial-to-mesenchymal transition can be induced to differentiate into adipocytes. In this review, molecular mechanisms, signal pathways, and the roles of various biological processes in adipose differentiation are summarized. Understanding the molecular mechanism of adipogenesis and adipose differentiation of cancer cells may contribute to cancer treatments that involve inducing differentiation into benign cells.

Classifying the Linkage between Adipose Tissue Inflammation and Tumor Growth through Cancer-Associated Adipocytes.

Recently, tumor microenvironment (TME) and its stromal constituents have provided profound insights into understanding alterations in tumor behavior. After each identification regarding the unique roles of TME compartments, non-malignant stromal cells are found to provide a sufficient tumorigenic niche for cancer cells. Of these TME constituents, adipocytes represent a dynamic population mediating endocrine effects to facilitate the crosstalk between cancer cells and distant organs, as well as the interplay with nearby tumor cells. To date, the prevalence of obesity has emphasized the significance of metabolic homeostasis along with adipose tissue (AT) inflammation, cancer incidence, and multiple pathological disorders. In this review, we summarized distinct characteristics of hypertrophic adipocytes and cancer to highlight the importance of an individual's metabolic health during cancer therapy. As AT undergoes inflammatory alterations inducing tissue remodeling, immune cell infiltration, and vascularization, these features directly influence the TME by favoring tumor progression. A comparison between inflammatory AT and progressing cancer could potentially provide crucial insights into delineating the complex communication network between uncontrolled hyperplastic tumors and their microenvironmental components. In turn, the comparison will unravel the underlying properties of dynamic tumor behavior, advocating possible therapeutic targets within TME constituents.

Gilthead seabream (Sparus aurata) in vitro adipogenesis and its endocrine regulation by leptin, ghrelin, and insulin

Leptin, ghrelin, and insulin influence lipid metabolism and thus can directly affect adipose tissue characteristics, modulating the organoleptic quality of aquaculture fish. The present study explored gilthead seabream (Sparus aurata) cultured preadipocytes development, and the regulation of adipogenesis by those three hormones. Preadipocytes presented a fibroblast-like phenotype during the proliferation phase that changed to round-shaped with an enlarged cytoplasm filled with lipid droplets after complete differentiation, confirming the characteristics of mature adipocytes. peroxisome proliferator-activated receptor-γ (pparγ) expression was higher at the beginning of the culture, while fatty acid synthase and 3-hydroxyacyl-CoA dehydrogenase gradually increased with cell maturation. The expression of lipoprotein lipase-like, lysosomal acid lipase (lipa), fatty acid translocase/cluster of differentiation-36 (cd36), and leptin receptor (lepr) were not affected during cell culture development; and undetectable expression levels were observed for leptin. Concerning regulation, leptin inhibited lipid accumulation significantly reducing pparγ and cd36 gene expression, both in early differentiating and mature adipocytes, while ghrelin decreased the expression of pparγ in the early differentiating phase but did not reduce intracellular lipid content significantly. Additional insulin past the onset of adipogenesis did not affect lipid accumulation either. In conclusion, at present culture conditions leptin has an anti-adipogenic function in differentiating preadipocytes of gilthead seabream and continues exerting this role in mature adipocytes, while ghrelin and insulin do not seem to influence adipogenesis progression. A better understanding of leptin, ghrelin, and insulin impact on the adipogenic process could help in the prevention of fat accumulation, improving aquaculture fish production and quality.

Morphological and functional characteristics of retrosternal adipose tissue and their relation to arterial stiffness parameters in patients after coronary artery bypass grafting

Background . The attention of many researchers is focused on studying the role of adipokines secreted by subcutaneous, visceral, epicardial, and perivascular adipose tissues in the pathogenesis of diseases of the cardiovascular system. At the same time, adipose tissue of retrosternal localization remains out of research focus. This pool of fat cells is formed at the site of the thymic involution and has a significant volume. However, their functional activity and participation in the development of cardiovascular pathology remain unexplored. Aim. To study the morphological characteristics of adipocytes of the retrosternal adipose tissue (RSAT) and their production of adipokines in comparison with epicardial (EAT) and subcutaneous adipose tissue (SCAT) and to investigate their relationships with arterial stiffness parameters in patients who underwent coronary artery bypass grafting. Materials and methods . The study included 17 patients (12 men/5 women aged 40–70 years) with the diagnosed coronary artery disease (CAD) who underwent coronary artery bypass grafting (CABG). Each patient underwent measurement of carotid-femoral pulse wave velocity (PWV) and aortic augmentation index (AIx) with the oscillometric device. Isolated adipocytes were obtained enzymatically from explants of SCAT, EAT and RSAT during coronary artery bypass grafting. The adipocytes were analyzed under the microscope at 200x magnification. The release of adiponectin, leptin and insulin was studied in the adipocyte supernatant after 1 hour incubation using ELISA. Results. It was found that adipocytes of the RSAT are smaller than adipocytes of SCAT: 83.96 ± 2.21 vs 98.62 ± 2.67 μm ( p = 0.00002), respectively, and comparable in size to adipocytes of EAT: 86.65 ± 1.33 μm. The release of adiponectin by adipocytes of the RSAT turned out to be comparable to the production of this adipokine in SCAT and EAT, however, adipocytes of the RSAT produce less leptin than SCAT and EAT: 0.26 (0.19; 0.27) ng/l vs 0.37 (0.28; 0.55) ( р = 0.01) and vs 0.32 (0.28; 0.44) ( р = 0.006) ng/ml, respectively. Furthermore, RSAT produce less insulin than SCAT and EAT: 1.56 (1.03; 2.08) vs 1.70 (0.99; 2.18) ng/ml, (р = 0.0022) and 1.76 (1.16; 2.40) ng/ml ( р = 0.006), respectively. A positive correlation was found between the secretion of leptin by adipocytes of the RSAT and the AIx ( r s = 0.52, p = 0.046). An inverse relationship was found between insulin secretion by retrosternal adipocytes and PWV r s = –0.55, p = 0.035). There was no relationship between the size of the retrosternal adipocyte or hypertrophy of the thymic adipocytes (more than 100 μm) and the production of leptin and insulin and arterial stiffness parameters. Conclusions . The data of our pilot study show that adipocyte hypertrophy of the retrosternal AT is not a significant marker of adipokine production disturbance . The observed relationships suggest that an increase in leptin production and reduced insulin secretion by retrosternal AT may contribute to the formation of adipokine-related arterial stiffness. Based on the data obtained, it can be assumed that adipokines produced by the retrosternal AT can participate in the formation of arterial stiffness in patients with coronary artery disease.

Cytological and functional characteristics of fascia adipocytes in rats: A unique population of adipocytes

The dermal adipocytes, superficial fascia and subcutaneous adipose tissue (SAT) exist in the interspaces between the dermis and muscular fascia. They are adjacent to each other and traditionally recognized as one SAT. Recently, the dermal adipocyte was redefined as a unique population independent from the SAT. Also, we identified a novel type of adipogenic progenitors in rat superficial fascia. This study aimed to examine cytological and functional characteristics of fascial adipocytes in rats. Superficial fascia had no adipocytes in neonatal rats but gradually appeared numbers of adipocytes in growing rats. Adipogenic progenitors were found to reside in fascia and had strong ability in spontaneous and induced adipogenic differentiation in vitro. Differentiated fascial adipocytes versus subcutaneous or visceral adipocytes expressed increased adipose triglyceride lipase but decreased beta-adrenoreceptor, perilipin-1 and hormone-sensitive lipase (HSL), thus having high basal lipolysis but low lipolysis response to catecholamines. Phosphorylation of perilipin-1 and HSL and translocation of HSL to lipid droplets were attenuated in response to catecholamines rather than post-adrenoreceptoral lipolytic stimulators. The results suggested that superficial fascia was an origin of adipocytes with distinct developmental, cytological and functional characteristics. We proposed that fascial adipocytes could be considered as a unique population of adipocytes in the body. The fascia origin of adipocytes as an adipogenic model might logically explain fat neogenesis occurred at anatomical locations where originally exist no adipose tissues and thereby no adipose-derived stromal precursors. Also, the special histoanatomical relations and overlaps between the dermis, superficial fascia, SAT, and their adipocytes were discussed.

In vivo study of metabolic dynamics and heterogeneity in brown and beige fat by label-free multiphoton redox and fluorescence lifetime microscopy.

In this work, the metabolic characteristics of adipose tissues in live mouse model were investigated using a multiphoton redox ratio and fluorescence lifetime imaging technology. By analyzing the intrinsic fluorescence of metabolic coenzymes, we measured the optical redox ratios of adipocytes in vivo and studied their responses to thermogenesis. The fluorescence lifetime imaging further revealed changes in protein bindings of metabolic coenzymes in the adipocytes during thermogenesis. Our study uncovered significant heterogeneity in the cellular structures and metabolic characteristics of thermogenic adipocytes in brown and beige fat. Subgroups of brown and beige adipocytes were identified based on the distinct lipid size distributions, redox ratios, fluorescence lifetimes and thermogenic capacities. The results of our study show that this label-free imaging technique can shed new light on in vivo study of metabolic dynamics and heterogeneity of adipose tissues in live organisms.

SUN-118 Interleukin-6 (IL-6) Decreases Mitochondrial Biogenesis In 3T3-L1 Pre-adipocytes And Adipocytes

The mitochondria are highly dynamic organelles specialized in metabolizing energy for the proper functioning of all cells. These organelles go through biogenesis cycles alternating between the fusion and fission of mitochondrial compartments, and adapt their morphology to the metabolic status of the cell, optimizing its function. During fusion, the mitochondria create networks that are essential during high mitochondrial function and energy usage. Conversely, fission is predominant in resting cells, during low energy demand and accountable for the removal of damaged mitochondria. Interleukin-6 (IL-6), a widely known inflammatory cytokine, has begun to be recognized for its role in the regulation of metabolism and mitochondrial function. Since normally functioning adipocytes are crucial in promoting metabolic health, in this study, we investigated the direct effect of IL-6 on mitochondrial morphology in adipocytes. To study the effect of IL-6 on mitochondria, we used 3T3-L1 pre-adipocytes and adipocytes as our cell culture model. On the 10th day after inducing differentiation, when majority of the cells showed the rounded, lipid droplet laden characteristics of adipocytes, the cells were treated with 200 mg/mL of IL-6 for 48 and 96 hours. The fluorescent dye, MitoTracker, was used to stain the mitochondria for imaging using confocal laser microscopy. Pre-adipocytes and adipocytes treated with IL-6 presented a more fragmented and punctate mitochondrial morphology compared to the control, suggesting that IL-6 promotes the fission rather than the fusion state of mitochondrial dynamics. A decrease in florescence intensity, which indicates decreased mitochondrial membrane potential, was observed preliminarily in some of the treatments. Overall, our results demonstrate that IL-6 may affect mitochondrial biogenesis, mitochondrial function and thus metabolic function in pre-adipocytes and adipocytes. In future, we will investigate IL-6 effects on mitochondrial function and gene expression.