Distinction of white, beige and brown adipocytes derived from mesenchymal stem cells

Effect of Different Fatty Acid Types on Mitochondrial Dysfunction Associated With Brown and Beige Adipose Tissue

Adipose tissue serves as a dynamic endocrine organ that is pivotal in metabolic regulation. Augmenting mitochondrial activity within this tissue holds promise in combating obesity. Mitochondrial function is intricately modulated by diverse fatty acid compositions. This comprehensive review aimed to elucidate the molecular mechanisms underlying mitochondrial dysfunction induced by various fatty acid profiles. While saturated fatty acids (SFAs) pose a threat to mitochondrial integrity, polyunsaturated fatty acids (PUFAs), notably n-3, mitigate SFA-induced damage, concurrently regulating thermogenic gene expression. With regard to monounsaturated fatty acids (MUFAs), their impact on mitochondrial function in adipose tissue remains relatively unexplored. Although human studies are imperative for comprehensive insights, prioritizing the consumption of n-3 fatty acids and MUFAs has emerged as a strategic approach, potentially enhancing mitochondrial biogenesis and metabolic pathways. This synthesis underscores the critical need for further investigation of the differential effects of fatty acid types on adipose tissue mitochondria, offering potential avenues for obesity intervention.

Timosaponin AⅢ inhibits ectopic lipid deposition and enhances the browning of white adipose tissue

Timosaponin AⅢ(TAⅢ), derived from the Chinese medicinal herb Anemarrhena asphodeloides Bunge, has been reported to have a range of pharmacological effects including improvement of learning and memory deficits, anti-tumor, hypoglycemic effect and anti-hypertension. This study explored the therapeutic effects and preliminary mechanisms of TAⅢ in improving insulin resistance in ob/ob mice. We found that treatment with 10 mg kg-1·d-1 of TAⅢ reduced the expression of SREBPs and alleviated ectopic lipid deposition by decreasing DAG accumulation in liver. The decrease of DAG further inhibited the membrane translocation of PKC-ε, releasing its inhibition of phosphorylation at Ser307 of IRS1, and ultimately enhancing the AKT signaling response to insulin stimulation. In addition, TAⅢ promoted the browning of iWAT by activating the PGC1α-UCP1 axis on ob/ob mice, thereby enhancing fatty acid oxidation and increasing energy consumption, thus reducing its interference with insulin signaling. TAⅢ worked by enhancing the function of adipose tissue and inhibited lipid synthesis. These actions collectively ameliorated metabolic disturbances associated with insulin resistance. Therefore, we preliminarily concluded that TAⅢ improved metabolic disturbances related to insulin resistance. However, further research is needed, additional studies are necessary to validate these potential mechanisms.

Transcriptional dynamics in type 2 diabetes progression is linked with circadian, thermogenic, and cellular stress in human adipose tissue

The prevalence of type 2 diabetes (T2D) has increased significantly over the past three decades, with an estimated 30-40% of cases remaining undiagnosed. Brown and beige adipose tissues are known for their remarkable catabolic capacity, and their ability to diminish blood glucose plasma concentration. Beige adipose tissue can be differentiated from adipose-derived stem cells or through transdifferentiation from white adipocytes. However, the impact of T2D progression on beige adipocytes' functional capacity remains unclear. Transcriptomic profiling of subcutaneous adipose tissue biopsies from healthy normal-weight, obese, prediabetic obese, and obese subjects diagnosed with T2D, reveals a progressive alteration in cellular processes associated with catabolic metabolism, circadian rhythms, thermogenesis-related signaling pathways, cellular stress, and inflammation. MAX is a potential transcription factor that links inflammation with the circadian clock and thermogenesis during the progression of T2D. This study unveils an unrecognized transcriptional circuit that increasingly disrupts subcutaneous adipose tissue oxidative capacity during the progression of T2D. These findings could open new research venues for developing chrono-pharmaceutical strategies to treat and prevent T2D.

Compound K promotes thermogenic signature and mitochondrial biogenesis via the UCP1-SIRT3-PGC1α signaling pathway

Compound K (CK), an active ingredient in ginseng, has anti-cancer, anti-inflammatory, and antioxidant properties. However, its effects on thermogenesis and mitochondrial dynamics in white adipose tissue (WAT) adipocytes are not well understood. This study explores CK's impact on thermogenesis and mitochondrial metabolism in cold-exposed mice and mouse stromal vascular fraction (SVF) cells. CK increased the expression of UCP1 and other brown/beige adipocyte markers (Cd137, Cytb, Letm1, Pgc1α, Prdm16, Tbp1, Tbx1, Uqcrc1) and mitochondrial biogenesis/dynamics factors (Cidea, Cox8b, Cycs, Dio2, Drp1, Fis1, Fgf21, Nrf1, Sirt3, Tfam) in 3T3-L1/iWAT SVF cells. CK enhanced mitochondrial respiration, reduced mitochondrial ROS levels, and restored MMP in iWAT SVF cells, leading to the differentiation of WAT into beige adipocytes, and that was also observed in cold-exposed subcutaneous tissue. CK administration to cold-exposed mice reduced fat droplet size and increased the number of mitochondria. Additionally, CK stimulated non-shivering thermogenesis, indicated by the upregulation of thermogenic and mitochondrial division proteins. The browning effect of CK was nullified by SIRT3 knockdown, suggesting that CK induces beige remodeling of WAT by regulating mitochondrial dynamics and SIRT3 expression. These findings suggest CK's potential as a therapeutic agent for obesity and metabolic disorders that promotes the transformation of WAT into a metabolically active beige phenotype.

LETM-domain containing 1 (LETMD1) protects against obesity via enhancing UCP1-independent energy expenditure in human beige adipocytes

Rationale: Brown and beige adipocytes are specialized fat cells that dissipate energy in the form of heat, and hold therapeutic potential for obesity and metabolic diseases. Although in the classical viewpoint brown and beige adipocytes dissipate energy solely via uncoupling protein 1 (UCP1), emerging evidence suggests the importance of non-canonical UCP1-independent energy expenditure in regulating energy expenditure, especially in human beige adipocytes. Leucine zipper-, EF-hand-containing transmembrane protein 1 domain containing 1 (LETMD1) was recently identified as a key protein in maintaining UCP1 expression and the thermogenic activity of brown adipocytes in animal models. But the exact function of LETMD1 and its mechanism of action in human beige adipocytes are unclear. Methods: We tested the function of LETMD1 in human induced pluripotent stem cell (hiPSC)-derived beige adipocytes in vitro in both wildtype (WT) and UCP1 knockout (KO) background. Furthermore, human beige adipocytes harboring a doxycycline-inducible LETMD1 expression cassette were transplanted to NOD/SCID mice and the function of LETMD1 in human beige adipocytes was evaluated in the in vivo setting. RNA-Seq was conducted in normal and LETMD1-overexpressing human beige adipocytes to examine the genes and pathways regulated by LETMD1. Using a knock-in human iPSC line, a preclinical small molecule compound library was screened for compounds increasing LETMD1 expression in human beige adipocytes. The effects of the compound in inducing LETMD1 and UCP1-independent energy expenditure in beige adipocytes were examined in vitro and in animal models. Results: LETMD1 plays an essential role in engaging energy dissipation, in a manner independent of UCP1, in human beige adipocytes. Transplantation of LETMD1-overexpressing human beige adipocytes improved whole-body metabolism of the recipient mice independent of UCP1. Mechanistically LETMD1 enhances the transcription of PPARGC1A, a key regulator of mitochondrial biogenesis. The expression of genes related to UCP1-independent energy expenditure, including creatine futile cycle, was also stimulated upon LETMD1 overexpression. Using LETMD1 reporter human beige adipocytes, SP-8356 was identified as a compound significantly increasing LETMD1 expression. Oral administration of SP-8356 induced genes related to UCP1-independent energy expenditure in beige adipocytes, and counteracted body weight gain and metabolic disorders in mice. Conclusion: Increased LETMD1 action, either genetically or pharmacologically, enhances the non-canonical UCP1-independent energy expenditure in beige adipocytes.

Muscle PGC-1α Overexpression Drives Metabolite Secretion Boosting Subcutaneous Adipocyte Browning

Muscle and adipose tissue (AT) are in mutual interaction through the integration of endocrine and biochemical signals, thus regulating whole-body function and physiology. Besides a traditional view of endocrine relationships that imply the release of cytokines and growth factors, it is becoming increasingly clear that a metabolic network involving metabolites as signal molecules also exists between the two tissues. By elevating the number and functionality of mitochondria, a key role in muscle metabolism is played by the master regulator of mitochondrial biogenesis peroxisome-proliferator-activated receptor-γ coactivator-1α (PGC-1α), that induces a fiber type shift from glycolytic to oxidative myofibers. As a consequence, the upregulation of muscle respiratory rate might affect metabolite production and consumption. However, the underlying mechanisms have not yet been fully elucidated. Here, we used a muscle-specific PGC-1α overexpressing mouse model (MCK-PGC-1α) to analyze the metabolite secretion profile of serum and culture medium recovered from MCK-PGC-1α muscle fibers by NMR. We revealed modified levels of different metabolites that might be ascribed to the metabolic activation of the skeletal muscle fibers. Notably, the dysregulated levels of these metabolites affected adipocyte differentiation, as well as the browning process in vitro and in vivo. Interestingly such effect was exacerbated in the subcutaneous WAT, while only barely present in the visceral WAT. Our data confirm a prominent role of PGC-1α as a trigger of mitochondrial function in skeletal muscle and propose a novel function of this master regulator gene in modulating the metabolite production in turn affecting the activation of WAT and its conversion toward the browning.

Cancer knocks you out by fasting: Cachexia as a consequence of metabolic alterations in cancer

Neoplastic transformation reprograms tumor and surrounding host cell metabolism, increasing nutrient consumption and depletion in the tumor microenvironment. Tumors uptake nutrients from neighboring normal tissues or the bloodstream to meet energy and anabolic demands. Tumor-induced chronic inflammation, a high-energy process, also consumes nutrients to sustain its dysfunctional activities. These tumor-related metabolic and physiological changes, including chronic inflammation, negatively impact systemic metabolism and physiology. Furthermore, the adverse effects of antitumor therapy and tumor obstruction impair the endocrine, neural, and gastrointestinal systems, thereby confounding the systemic status of patients. These alterations result in decreased appetite, impaired nutrient absorption, inflammation, and shift from anabolic to catabolic metabolism. Consequently, cancer patients often suffer from malnutrition, which worsens prognosis and increases susceptibility to secondary adverse events. This review explores how neoplastic transformation affects tumor and microenvironment metabolism and inflammation, leading to poor prognosis, and discusses potential strategies and clinical interventions to improve patient outcomes.

Embryonic Thermal Programming and Dietary Baicalein Supplementation Post-Hatch: Effects on Broiler Adipose Tissue Deposition

Optimization of growth performance and fat metabolism in broilers are critical for meat quality and overall production efficiency. This experiment investigated the effects of dietary baicalein supplementation and embryonic heat conditioning (EHC) on the growth performance and adipose tissue metabolism of 10-day old broilers. Fertile eggs were divided into control and EHC groups, with EHC eggs exposed to intermittent heating (39.5 °C) from day 7 to day 16 of incubation. Hatched chicks were further divided into four groups: CC (control control), CT (control treatment with baicalein), EC (embryonic heat control), and ET (embryonic heat treatment with baicalein), and were fed ad libitum. On day 10 post-hatch, blood and adipose tissue samples were collected for analysis. C/EBPα mRNA was lower in the ET group compared to the EC group and higher in the CT group compared to the CC group. PPARγ and HSL mRNAs were elevated in both the ET and CT groups relative to their controls. Additionally, plasma non-esterified fatty acid (NEFA) levels were significantly higher in the CT group compared to the CC group. These results indicate that baicalein supplementation, particularly when combined with embryonic heat conditioning, can modulate fat metabolism and potentially improve the growth performance of broilers, thereby offering insights into strategies for enhancing poultry production.

Characteristics of T2* and anisotropy parameters in inguinal and epididymal adipose tissues after cold exposure in mice

White adipose tissue (WAT) in mice undergoes browning in response to cold exposure. Brown and beige adipocytes contain multilocular lipid droplets and abundant iron-containing mitochondria expressing uncoupling protein 1 (UCP-1). Cold exposure-induced browning WAT is accompanied by increased density of blood vessels and sympathetic nerve fibres. A previous study reported a more than threefold increase in sympathetic nerve dendritic tone in inguinal white adipose tissue (iWAT) after cold exposure. Therefore, we hypothesized that water molecule diffusion would be more restricted in brown and beige adipocytes compared to white adipocytes. The characteristics of T2* values and anisotropy parameters by diffusion tensor imaging (DTI) in browning WAT are unclear. The aim of the present study was to investigate the effect of cold exposure on T2* values and anisotropy parameters (fractional anisotropy [FA], apparent diffusion coefficient [ADC], radial diffusivity [RD] and eigenvalues λ1, λ2, λ3) in brown adipose tissue (BAT), iWAT and epididymal white adipose tissue (epiWAT). Furthermore, these parameters were investigated in vivo through additional validation experiments in three control mice. Mice in the cold exposure (CE) group were exposed to a cold environment at 4 °C for 10 days, while these in the control (C) group were maintained at 22 °C throughout the experiment. T2* values, FA, ADC, RD and eigenvalues (λ1, λ2, λ3) were measured in BAT, iWAT and epiWAT using a 9.4T magnetic resonance scanner (Bruker Biospin AG). T2* values of epiWAT in the C group were significantly higher than these of BAT in the C group and iWAT in the CE group. No significant differences were observed between groups for FA, ADC, RD, λ1 and λ2 of iWAT and epiWAT. However, the λ3 values of iWAT and epiWAT in the CE group were significantly higher than these of iWAT, epiWAT and BAT in the C group. Compared to ex vivo measurements, in vivo measurements in control mice showed higher T2* values with reduced intertissue variability while maintaining tissue-specific patterns. These results suggest that T2* values and anisotropy parameters might serve as potential markers for the assessment of adipose tissue plasticity. Further studies are required to investigate their utility as non-invasive indicators of browning WAT.

Comprehensive phenotypic assessment of nonsense mutations in mitochondrial ND5 in mice

Mitochondrial dysfunction induced by mitochondrial DNA (mtDNA) mutations has been implicated in various human diseases. A comprehensive analysis of mitochondrial genetic disorders requires suitable animal models for human disease studies. While gene knockout via premature stop codons is a powerful method for investigating the unique functions of target genes, achieving knockout of mtDNA has been rare. Here, we report the genotypes and phenotypes of heteroplasmic MT-ND5 gene-knockout mice. These mutant mice presented damaged mitochondrial cristae in the cerebral cortex, hippocampal atrophy, and asymmetry, leading to learning and memory abnormalities. Moreover, mutant mice are susceptible to obesity and thermogenetic disorders. We propose that these mtDNA gene-knockdown mice could serve as valuable animal models for studying the MT-ND5 gene and developing therapies for human mitochondrial disorders in the future.

The Role of Matrix Stiffness And Viscosity on Lipid Phenotype And Fat Lineage Potential

Autologous fat transfer is a common procedure that patients undergo to rejuvenate large soft tissue defects. However, these surgeries are complicated by limited tissue sources, donor-site morbidity, and necrosis. While the biofabrication of fat tissue can serve as a clinical option for reconstructive surgery, the influence of matrix mechanics, specifically stiffness and viscosity, on adipogenesis requires further elucidation. Additionally, the effects of these mechanical parameters on metabolic and thermogenic fat potential have yet to be investigated. In this study, gelatin methacryloyl (GelMA) polymers with varying degrees of methacrylation (DoM) were fabricated to create matrices with different stiffnesses and viscosities. Human adipose-derived mesenchymal stem cells were then encapsulated in mechanically tunable GelMA and underwent adipogenesis to investigate the effects of matrix mechanics on lipid phenotype and fat potential. Mechanical testing confirmed that GelMA stiffness was regulated by DoM and weight composition, whereas viscosity was determined by the latter. Further work revealed that while lipid phenotype became more enriched as matrix stiffness and viscosity declined, the potential toward metabolic and thermogenic fat appeared to be more viscous dependent rather than stiffness dependent. In addition, fatty acid binding protein 4 and uncoupling protein 1 gene expression exhibited viscous-dependent behavior despite comparable levels of peroxisome proliferator-activated receptor gamma. However, despite the superior role of viscosity, lipid quantity and mitochondrial abundance demonstrated stiffness-dependent behavior. Overall, this work revealed that matrix viscosity played a more superior role than stiffness in driving adipogenesis and distinguishing between metabolic and thermogenic fat potential. Ultimately, this differentiation in fat production is important for engineering ideal adipose tissue for large soft tissue defects.

The Different Shades of Thermogenic Adipose Tissue

PURPOSE OF REVIEW

By providing a concise overview of adipose tissue types, elucidating the regulation of adipose thermogenic capacity in both physiological contexts and chronic wasting diseases (a protracted hypermetabolic state that precipitates sustained catabolism and consequent progressive corporeal atrophy), and most importantly, delving into the ongoing discourse regarding the role of adipose tissue thermogenic activation in chronic wasting diseases, this review aims to provide researchers with a comprehensive understanding of the field.

RECENT FINDINGS

Adipose tissue, traditionally classified as white, brown, and beige (brite) based on its thermogenic activity and potential, is intricately regulated by complex mechanisms in response to exercise or cold exposure. This regulation is adipose depot-specific and dependent on the duration of exposure. Excessive thermogenic activation of adipose tissue has been observed in chronic wasting diseases and has been considered a pathological factor that accelerates disease progression. However, this conclusion may be confounded by the detrimental effects of excessive lipolysis. Recent research also suggests that such activation may play a beneficial role in the early stages of chronic wasting disease and provide potential therapeutic effects. A more comprehensive understanding of the changes in adipose tissue thermogenesis under physiological and pathological conditions, as well as the underlying regulatory mechanisms, is essential for the development of novel interventions to improve health and prevent disease.

A Mixture of Lactobacillus HY7601 and KY1032 Regulates Energy Metabolism in Adipose Tissue and Improves Cholesterol Disposal in High-Fat-Diet-Fed Mice

We aimed to characterize the anti-obesity and anti-atherosclerosis effects of Lactobacillus curvatus HY7601 and Lactobacillus plantarum KY1032 using high-fat diet (HFD)-fed obese C57BL/6 mice. We divided the mice into control (CON), HFD, HFD with 108 CFU/kg/day probiotics (HFD + KL, HY7301:KY1032 = 1:1), and HFD with 109 CFU/kg/day probiotics (HFD + KH, HY7301:KY1032 = 1:1) groups and fed/treated them during 7 weeks. The body mass, brown adipose tissue (BAT), inguinal white adipose tissue (iWAT), and epididymal white adipose tissue (eWAT) masses and the total cholesterol and triglyceride concentrations were remarkably lower in probiotic-treated groups than in the HFD group in a dose-dependent manner. In addition, the expression of uncoupling protein 1 in the BAT, iWAT, and eWAT was significantly higher in probiotic-treated HFD mice than in the HFD mice, as demonstrated by immunofluorescence staining and Western blotting. We also measured the expression of cholesterol transport genes in the liver and jejunum and found that the expression of those encoding liver-X-receptor α, ATP-binding cassette transporters G5 and G8, and cholesterol 7α-hydroxylase were significantly higher in the HFD + KH mice than in the HFD mice. Thus, a Lactobacillus HY7601 and KY1032 mixture with 109 CFU/kg/day concentration can assist with body weight regulation through the management of lipid metabolism and thermogenesis.

Asprosin contributes to pathogenesis of obesity by adipocyte mitophagy induction to inhibit white adipose browning in mice

BACKGROUND

Asprosin (ASP) is a newly discovered adipokine secreted by white adipose tissue (WAT), which can regulate the homeostasis of glucose and lipid metabolism. However, it is not clear whether it can regulate the browning of WAT and mitophagy during the browning process. Accordingly, this study aims to investigate the effects and possible mechanisms of ASP on the browning of WAT and mitophagy in vivo and in vitro.

METHODS

In in vivo experiments, some mouse models were used including adipose tissue ASP-specific deficiency (ASP-/-), high fat diet (HFD)-induced obesity and white adipose browning; in in vitro experiments, some cell models were also established and used, including ASP-deficient 3T3-L1 preadipocyte (ASP-/-) and CL-316243 (CL, 1 µM)-induced browning. Based on these models, the browning of WAT and mitophagy were evaluated by morphology, functionality and molecular markers.

RESULTS

Our in vivo data show that adipose tissue-specific deletion of ASP contributes to weight loss in mice; supplementation of ASP inhibits the expressions of browning-related proteins including UCP1, PRDM16 and PGC1ɑ during the cold exposure-induced browning, and promotes the expressions of mitophagy-related proteins including PINK1 and Parkin under the conditions of whether normal diet (ND) or HFD. Similarly, our in vitro data also show that the deletion of ASP in 3T3-L1 cells significantly increases the expressions of the browning-related proteins and decreases the expressions of the mitophagy-related proteins.

CONCLUSIONS

These data demonstrate that ASP deletion can facilitate the browning and inhibit mitophagy in WAT. The findings will lay an experimental foundation for the development of new drugs targeting ASP and the clinical treatment of metabolic diseases related to obesity.

7-MEGA™ inhibits adipogenesis in 3T3-L1 adipocytes and suppresses obesity in high-fat-diet-induced obese C57BL/6 mice

BACKGROUND

Overweight, often known as obesity, is the abnormal and excessive accumulation of fat that exposes the health of a person at risk by increasing the likelihood that they may experience many chronic conditions. Consequently, obesity has become a global health threat, presenting serious health issues, and attracting a lot of attention in the healthcare profession and the scientific community.

METHOD

This study aims to explore the anti-adipogenic properties of 7-MEGA™ in an attempt to address obesity, using both in vitro and in vivo research. The effects of 7MEGA™ at three distinct concentrations were investigated in obese mice who were given a high-fat diet (HFD) and 3T3-L1 adipocytes.

RESULTS

7MEGA™ decreased the total fat mass, overall body weight, and the perirenal and subcutaneous white adipose tissue (PWAT and SWAT) contents in HFD mice. Additionally, 7MEGA™ showed promise in improving the metabolic health of individuals with obesity and regulate the levels of insulin hormone, pro-inflammatory cytokines and adipokines. Furthermore, Peroxisome proliferator-activated receptors (PPAR) α and γ, Uncoupling Protein 1 (UCP-1), Sterol Regulatory Element-Binding Protein 1 (SREBP-1), Fatty Acid-Binding Protein 4 (FABP4), Fatty Acid Synthase (FAS), Acetyl-CoA Carboxylase (ACC), Stearoyl-CoA Desaturase-1 (SCD-1) and CCAAT/Enhancer-Binding Protein (C/EBPα) were among the adipogenic regulators that 7MEGA™ could regulate.

CONCLUSION

In summary, this study uncovered that 7MEGA™ demonstrates anti-adipogenic and anti-obesity effects, suggesting its potential in combating obesity.

Inhibition of activin receptor 2 signalling ameliorates metabolic dysfunction-associated steatotic liver disease in western diet/L-NAME induced cardiometabolic disease

OBJECTIVE

Blockade of activin 2 receptor (ACVR2) signaling has been shown to improve insulin sensitivity and aid in weight loss. Inhibition of ACVR2 signaling restores cardiac function in multiple heart failure models. However, its potential in the treatment of obesity-related cardiometabolic disease remains unknown. Here, we investigated targeting ACVR2 signaling in cardiometabolic disease manifested with metabolic dysfunction-associated steatotic liver disease (MASLD).

METHODS

Mice were fed a high-fat, high-sugar diet combined with the administration of nitric oxide synthase inhibitor L-NAME in drinking water, which causes hypertensive stress. For the last eight weeks, the mice were treated with the soluble ACVR2B decoy receptor (sACVR2B-Fc).

RESULTS

sACVR2B-Fc protected against the development of comorbidities associated with cardiometabolic disease. This was most pronounced in the liver where ACVR2 blockade attenuated the development of MASLD including cessation of pro-fibrotic activation. It also significantly reduced total plasma cholesterol levels, impeded brown adipose tissue whitening, and improved cardiac diastolic function. In vitro, ACVR2 ligands activin A, activin B and GDF11 induced profibrotic signaling and the proliferation of human cardiac fibroblasts.

CONCLUSIONS

Blockade of ACVR2B exerts broad beneficial effects for therapy of cardiometabolic disease. By reducing obesity, ameliorating cardiovascular deterioration and restraining MASLD, blockade of ACVR2B signaling proves a potential target in MASLD and its comorbidities.

Unveiling the role of interleukin-6 in pancreatic cancer occurrence and progression

Pancreatic cancer is difficult to diagnose early and progresses rapidly. Researchers have found that a cytokine called Interleukin-6 (IL-6) is involved in the entire course of pancreatic cancer, promoting its occurrence and development. From the earliest stages of pancreatic intraepithelial neoplasia to the invasion and metastasis of pancreatic cancer cells and the appearance of tumor cachexia, IL-6 drives oncogenic signal transduction pathways and immune escape that accelerate disease progression. IL-6 is considered a biomarker for pancreatic cancer diagnosis and prognosis, as well as a potential target for treatment. IL-6 antibodies are currently being explored as a hot topic in oncology. This article aims to systematically explain how IL-6 induces the deterioration of normal pancreatic cells, with the goal of finding a breakthrough in pancreatic cancer diagnosis and treatment.

Unveiling the Potential of Natural Compounds: A Comprehensive Review on Adipose Thermogenesis Modulation

The process of adipocyte browning has recently emerged as a novel therapeutic target for combating obesity and obesity-related diseases. Non-shivering thermogenesis is the process of biological heat production in mammals and is primarily mediated via brown adipose tissue (BAT). The recruitment and activation of BAT can be induced through chemical drugs and nutrients, with subsequent beneficial health effects through the utilization of carbohydrates and fats to generate heat to maintain body temperature. However, since potent drugs may show adverse side effects, nutritional or natural substances could be safe and effective as potential adipocyte browning agents. This review aims to provide an extensive overview of the natural food compounds that have been shown to activate brown adipocytes in humans, animals, and in cultured cells. In addition, some key genetic and molecular targets and the mechanisms of action of these natural compounds reported to have therapeutic potential to combat obesity are discussed.

An update on the secretory functions of brown, white, and beige adipose tissue: Towards therapeutic applications

Adipose tissue, including white adipose tissue (WAT), brown adipose tissue (BAT), and beige adipose tissue, is vital in modulating whole-body energy metabolism. While WAT primarily stores energy, BAT dissipates energy as heat for thermoregulation. Beige adipose tissue is a hybrid form of adipose tissue that shares characteristics with WAT and BAT. Dysregulation of adipose tissue metabolism is linked to various disorders, including obesity, type 2 diabetes, cardiovascular diseases, cancer, and infertility. Both brown and beige adipocytes secrete multiple molecules, such as batokines, packaged in extracellular vesicles or as soluble signaling molecules that play autocrine, paracrine, and endocrine roles. A greater understanding of the adipocyte secretome is essential for identifying novel molecular targets in treating metabolic disorders. Additionally, microRNAs show crucial roles in regulating adipose tissue differentiation and function, highlighting their potential as biomarkers for metabolic disorders. The browning of WAT has emerged as a promising therapeutic approach in treating obesity and associated metabolic disorders. Many browning agents have been identified, and nanotechnology-based drug delivery systems have been developed to enhance their efficacy. This review scrutinizes the characteristics of and differences between white, brown, and beige adipose tissues, the molecular mechanisms involved in the development of the adipocytes, the significant roles of batokines, and regulatory microRNAs active in different adipose tissues. Finally, the potential of WAT browning in treating obesity and atherosclerosis, the relationship of BAT with cancer and fertility disorders, and the crosstalk between adipose tissue with circadian system and circadian disorders are also investigated.

Anti-obesity and metabolic benefits of metformin: Comparison of different delivery routes

Obesity is a severe public health problem. Healthy lifestyle interventions are commonly recommended for fighting obesity. But they are hard to follow and have low efficacy. Pharmacotherapy and surgery are of high efficacy but are beset with side effects. Browning subcutaneous white adipose tissue (WAT) is a practical and efficient approach for combating obesity. Metformin, a commonly used FDA-approved antidiabetic drug, is potent to induce browning of WAT through phosphorylation and activation of AMP-activated protein kinase. However, oral administration of metformin has low oral bioavailability, fast renal clearance, and low target specificity that limit metformin's application in browning WAT. Local and transdermal delivery of metformin directly to subcutaneous WAT using injection or microneedle (MN) in combination with iontophoresis (INT) may solve these problems. In this paper, we administered metformin to C57BL/6J obese mice using the following three routes: transdermal delivery (MN and INT), local injection into inguinal WAT (IgWAT, a type of subcutaneous WAT in mice), and oral gavage. The anti-obesity and metabolic effects of metformin via these delivery routes were determined and compared. As compared to local IgWAT injection and oral gavage delivery, transdermal delivery of metformin using MN and INT resulted in 9% lower body weight and 7% decrease in body fat% accompanied by improved energy metabolism and decreased inflammation through browning IgWAT in obese C57BL/6J mice. Transdermal delivery of metformin using MN and INT is an effective approach in browning subcutaneous WAT for combating obesity and improving metabolic health.

The Effect of an Innovative Combination of Bergamot Polyphenolic Fraction and Cynara cardunculus L. Extract on Weight Gain Reduction and Fat Browning in Obese Mice

Obesity is one of the world's most serious public health issues, with a high risk of developing a wide range of diseases. As a result, focusing on adipose tissue dysfunction may help to prevent the metabolic disturbances commonly associated with obesity. Nutraceutical supplementation may be a crucial strategy for improving WAT inflammation and obesity and accelerating the browning process. The aim of this study was to perform a preclinical "proof of concept" study on Bergacyn®, an innovative formulation originating from a combination of bergamot polyphenolic fraction (BPF) and Cynara cardunculus (CyC), for the treatment of adipose tissue dysfunction. In particular, Bergacyn® supplementation in WD/SW-fed mice at doses of 50 mg/kg given orally for 12 weeks, was able to reduce body weight and total fat mass in the WD/SW mice, in association with an improvement in plasma biochemical parameters, including glycemia, total cholesterol, and LDL levels. In addition, a significant reduction in serum ALT levels was highlighted. The decreased WAT levels corresponded to an increased weight of BAT tissue, which was associated with a downregulation of PPARγ as compared to the vehicle group. Bergacyn® was able to restore PPARγ levels and prevent NF-kB overexpression in the WAT of mice fed a WD/SW diet, suggesting an improved oxidative metabolism and inflammatory status. These results were associated with a significant potentiation of the total antioxidant status in WD/SW mice. Finally, our data show, for the first time, that Bergacyn® supplementation may be a valuable approach to counteract adipose tissue dysfunction and obesity-associated effects on cardiometabolic risk.

Betanin from Beetroot (Beta vulgaris L.) Regulates Lipid Metabolism and Promotes Fat Browning in 3T3-L1 Adipocytes

Fat browning, which converts white adipose tissue to brown, has attracted attention as a promising strategy for the treatment of obesity. Betanin (BT) has been reported to have potential anti-obesity activity. 3T3-L1 cells were differentiated for 7 days during BT treatment. The BT concentration range for the study was determined using an MTT assay, and lipid accumulation was evaluated by Oil-Red-O staining. The expression of protein level was analyzed by Western blot. Immunofluorescence images were performed with confocal microscopy to visually show the amount and location of thermogenesis factor uncoupling protein1 (UCP1) and mitochondria. qRT-PCR was performed to evaluate mRNA expression. BT inhibited lipid accumulation and increased the expression of UCP1, peroxisome-proliferator-activated receptor gamma (PPARγ), and PPARγ coactivator-1 alpha (PGC-1α). In addition, the increases in beige adipocyte-specific markers were observed, supporting BT-mediated browning of the fat tissue. The UCP1 was localized in the inner membrane of the mitochondria, and its expression was associated with mitochondrial activation. Consistent with this, the mRNA expression of mitochondrial biogenesis markers increased in 3T3-L1 cells after BT treatment. Immunofluorescence staining also indicated an increased number of mitochondria and UCP1, respectively. Moreover, BT inhibited lipogenesis and enhanced lipolysis and fatty acid oxidation. This mechanism has been suggested to be mediated by an adenosine monophosphate-activated protein kinase (AMPK) pathway. BT induces fat browning and regulates lipid metabolism via the AMPK-mediated pathway in 3T3-L1 cells, suggesting that BT can be a promising candidate for controlling obesity.

Effect of 2'-Fucosyllactose on Beige Adipocyte Formation in 3T3-L1 Adipocytes and C3H10T1/2 Cells

2'-Fucosyllactose (2'-FL), the functional oligosaccharide naturally present in milk, has been shown to exert health benefits. This study was aimed to investigate the effect of 2'-fucosyllactose (2'-FL) on the browning of white adipose tissue in 3T3-L1 adipocytes and C3H10T1/2 cells. The results revealed that 2'-FL decreased lipid accumulations with reduced intracellular triglyceride contents in vitro. 2'-FL intervention increased the mitochondria density and the proportion of UCP1-positive cells. The mRNA expressions of the mitochondrial biogenesis-related and browning markers (Cox7a, Cyto C, Tfam, Ucp1, Pgc1α, Prdm16, Cidea, Elovl3, Pparα, CD137, and Tmem26) were increased after 2'-FL intervention to some extent. Similarly, the protein expression of the browning markers, including UCP1, PGC1α, and PRDM16, was up-regulated in the 2'-FL group. Additionally, an adenosine monophosphate-activated protein kinase (AMPK) inhibitor, compound C (1 μM), significantly decreased the induction of thermogenic proteins expressions mediated by 2'-FL, indicating that the 2'-FL-enhanced beige cell formation was partially dependent on the AMPK pathway. In conclusion, 2'-FL effectively promoted the browning of white adipose in vitro.

Cancer Cachexia: Underlying Mechanisms and Potential Therapeutic Interventions

Cancer cachexia, a multifactorial metabolic syndrome developed during malignant tumor growth, is characterized by an accelerated loss of body weight accompanied by the depletion of skeletal muscle mass. This debilitating condition is associated with muscle degradation, impaired immune function, reduced functional capacity, compromised quality of life, and diminished survival in cancer patients. Despite the lack of the known capability of fully reversing or ameliorating this condition, ongoing research is shedding light on promising preclinical approaches that target the disrupted mechanisms in the pathophysiology of cancer cachexia. This comprehensive review delves into critical aspects of cancer cachexia, including its underlying pathophysiological mechanisms, preclinical models for studying the progression of cancer cachexia, methods for clinical assessment, relevant biomarkers, and potential therapeutic strategies. These discussions collectively aim to contribute to the evolving foundation for effective, multifaceted counteractive strategies against this challenging condition.

Inhibition of PPARγ by BZ26, a GW9662 derivate, attenuated obesity-related breast cancer progression by inhibiting the reprogramming of mature adipocytes into to cancer associate adipocyte-like cells

Obesity has been associated with the development of 13 different types of cancers, including breast cancer. Evidence has indicated that cancer-associated adipocytes promote the proliferation, invasion, and metastasis of cancer. However, the mechanisms that link CAAs to the progression of obesity-related cancer are still unknown. Here, we found the mature adipocytes in the visceral fat of HFD-fed mice have a CAAs phenotype but the stromal vascular fraction of the visceral fat has not. Importantly, we found the derivate of the potent PPARγ antagonist GW9662, BZ26 inhibited the reprogramming of mature adipocytes in the visceral fat of HFD-fed mice into CAA-like cells and inhibited the proliferation and invasion of obesity-related breast cancer. Further study found that it mediated the browning of visceral, subcutaneous and perirenal fat and attenuated inflammation of adipose tissue and metabolic disorders. For the mechanism, we found that BZ26 bound and inhibited PPARγ by acting as a new modulator. Therefore, BZ26 serves as a novel modulator of PPARγ activity, that is, capable of inhibiting obesity-related breast cancer progression by inhibiting of CAA-like cell formation, suggesting that inhibiting the reprogramming of mature adipocytes into CAAs or CAA-like cells may be a potential therapeutic strategy for obesity-related cancer treatment.

β-Hydroxy-β-methyl Butyrate Regulates the Lipid Metabolism, Mitochondrial Function, and Fat Browning of Adipocytes

A growing number of in vivo studies demonstrated that β-hydroxy-β-methyl butyrate (HMB) can serve as a lipid-lowering nutrient. Despite this interesting observation, the use of adipocytes as a model for research is yet to be explored. To ascertain the effects of HMB on the lipid metabolism of adipocytes and elucidate the underlying mechanisms, the 3T3-L1 cell line was employed. Firstly, serial doses of HMB were added to 3T3-L1 preadipocytes to evaluate the effects of HMB on cell proliferation. HMB (50 µM) significantly promoted the proliferation of preadipocytes. Next, we investigated whether HMB could attenuate fat accumulation in adipocytes. The results show that HMB treatment (50 µM) reduced the triglyceride (TG) content. Furthermore, HMB was found to inhibit lipid accumulation by suppressing the expression of lipogenic proteins (C/EBPα and PPARγ) and increasing the expression of lipolysis-related proteins (p-AMPK, p-Sirt1, HSL, and UCP3). We also determined the concentrations of several lipid metabolism-related enzymes and fatty acid composition in adipocytes. The HMB-treated cells showed reduced G6PD, LPL, and ATGL concentrations. Moreover, HMB improved the fatty acid composition in adipocytes, manifested by increases in the contents of n6 and n3 PUFAs. The enhancement of the mitochondrial respiratory function of 3T3-L1 adipocytes was confirmed via Seahorse metabolic assay, which showed that HMB treatment elevated basal mitochondrial respiration, ATP production, H⁺ leak, maximal respiration, and non-mitochondrial respiration. In addition, HMB enhanced fat browning of adipocytes, and this effect might be associated with the activation of the PRDM16/PGC-1α/UCP1 pathway. Taken together, HMB-induced changes in the lipid metabolism and mitochondrial function may contribute to preventing fat deposition and improving insulin sensitivity.

Mitochondrial Dysfunction: At the Nexus between Alcohol-Associated Immunometabolic Dysregulation and Tissue Injury

Alcohol misuse, directly or indirectly as a result of its metabolism, negatively impacts most tissues, including four with critical roles in energy metabolism regulation: the liver, pancreas, adipose, and skeletal muscle. Mitochondria have long been studied for their biosynthetic roles, such as ATP synthesis and initiation of apoptosis. However, current research has provided evidence that mitochondria participate in myriad cellular processes, including immune activation, nutrient sensing in pancreatic β-cells, and skeletal muscle stem and progenitor cell differentiation. The literature indicates that alcohol impairs mitochondrial respiratory capacity, promoting reactive oxygen species (ROS) generation and disrupting mitochondrial dynamics, leading to dysfunctional mitochondria accumulation. As discussed in this review, mitochondrial dyshomeostasis emerges at a nexus between alcohol-disrupted cellular energy metabolism and tissue injury. Here, we highlight this link and focus on alcohol-mediated disruption of immunometabolism, which refers to two distinct, yet interrelated processes. Extrinsic immunometabolism involves processes whereby immune cells and their products influence cellular and/or tissue metabolism. Intrinsic immunometabolism describes immune cell fuel utilization and bioenergetics that affect intracellular processes. Alcohol-induced mitochondrial dysregulation negatively impacts immunometabolism in immune cells, contributing to tissue injury. This review will present the current state of literature, describing alcohol-mediated metabolic and immunometabolic dysregulation from a mitochondrial perspective.

Impact of Combined Baricitinib and FTI Treatment on Adipogenesis in Hutchinson-Gilford Progeria Syndrome and Other Lipodystrophic Laminopathies

Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disease that causes premature aging symptoms, such as vascular diseases, lipodystrophy, loss of bone mineral density, and alopecia. HGPS is mostly linked to a heterozygous and de novo mutation in the LMNA gene (c.1824 C > T; p.G608G), resulting in the production of a truncated prelamin A protein called "progerin". Progerin accumulation causes nuclear dysfunction, premature senescence, and apoptosis. Here, we examined the effects of baricitinib (Bar), an FDA-approved JAK/STAT inhibitor, and a combination of Bar and lonafarnib (FTI) treatment on adipogenesis using skin-derived precursors (SKPs). We analyzed the effect of these treatments on the differentiation potential of SKPs isolated from pre-established human primary fibroblast cultures. Compared to mock-treated HGPS SKPs, Bar and Bar + FTI treatments improved the differentiation of HGPS SKPs into adipocytes and lipid droplet formation. Similarly, Bar and Bar + FTI treatments improved the differentiation of SKPs derived from patients with two other lipodystrophic diseases: familial partial lipodystrophy type 2 (FPLD2) and mandibuloacral dysplasia type B (MADB). Overall, the results show that Bar treatment improves adipogenesis and lipid droplet formation in HGPS, FPLD2, and MADB, indicating that Bar + FTI treatment might further ameliorate HGPS pathologies compared to lonafarnib treatment alone.

Understanding the relationship between cancer associated cachexia and hypoxia-inducible factor-1

Cancer-associated cachexia (CAC) is a multifactorial disorder characterized by an unrestricted loss of body weight as a result of muscle and adipose tissue atrophy. Cachexia is influenced by several factors, including decreased metabolic activity and food intake, an imbalance between energy uptake and expenditure, excessive catabolism, and inflammation. Cachexia is highly associated with all types of cancers responsible for more than half of cancer-related mortalities worldwide. In healthy individuals, adipose tissue significantly regulates energy balance and glucose homeostasis. However, in metastatic cancer patients, CAC occurs mainly because of an imbalance between muscle protein synthesis and degradation which are organized by certain extracellular ligands and associated signaling pathways. Under hypoxic conditions, hypoxia-inducible factor-1 (HIF-1α) accumulated and translocated to the nucleus and activate numerous genes involved in cell survival, invasion, angiogenesis, metastasis, metabolic reprogramming, and cancer stemness. On the other hand, the ubiquitination proteasome pathway is inhibited during low O2 levels which promote muscle wasting in cancer patients. Therefore, understanding the mechanism of the HIF-1 pathway and its metabolic adaptation to biomolecules is important for developing a novel therapeutic method for cancer and cachexia therapy. Even though many HIF inhibitors are already in a clinical trial, their mechanism of action remains unknown. With this background, this review summarizes the basic concepts of cachexia, the role of inflammatory cytokines, pathways connected with cachexia with special reference to the HIF-1 pathway and its regulation, metabolic changes, and inhibitors of HIFs.

Metallothionein 3 Inhibits 3T3-L1 Adipocyte Differentiation via Reduction of Reactive Oxygen Species

Metallothionein 3 (MT3), also known as a neuronal growth-inhibitory factor, is a member of the metallothionein family and is involved in a variety of biological functions, including protection against metal toxicity and reactive oxygen species (ROS). However, less is known about the role of MT3 in the differentiation of 3T3-L1 cells into adipocytes. In this study, we observed that MT3 levels were downregulated during 3T3-L1 adipocyte differentiation. Mt3 overexpression inhibited adipocyte differentiation and reduced the levels of the adipogenic transcription factors C/EBPα and PPARγ. Further analyses showed that MT3 also suppressed the transcriptional activity of PPARγ, and this effect was not mediated by a direct interaction between MT3 with PPARγ. In addition, Mt3 overexpression resulted in a decrease in ROS levels during early adipocyte differentiation, while treatment with antimycin A, which induces ROS generation, restored the ROS levels. Mt3 knockdown, on the other hand, elevated ROS levels, which were suppressed upon treatment with the antioxidant N-acetylcysteine. Our findings indicate a previously unknown role of MT3 in the differentiation of 3T3-L1 cells into adipocytes and provide a potential novel target that might facilitate obesity treatment.

Naringin promotes fat browning mediated by UCP1 activation via the AMPK signaling pathway in 3T3-L1 adipocytes

Induction of the brown adipocyte-like phenotype in white adipocytes (fat browning) is considered a promising therapeutic strategy to treat obesity. Naringin, a citrus flavonoid, has antioxidant, anti-inflammatory, and anticancer activities. We examined the application of naringin as an anti-obesity compound based on an investigation of its induction of fat browning in 3T3-L1 adipocytes. Naringin did not induce lipid accumulation in differentiated 3T3-L1 adipocytes. Additionally, naringin reduced the expression levels of proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein alpha (C/EBPα) involved in adipogenesis during lipid metabolism and increased the levels of PPARα and adiponectin involved in fatty acid oxidation. The expression levels of fat browning markers uncoupling protein 1 (UCP1; involved in thermogenesis) and PR domain containing 16 (PRDM16) increased. In addition, naringin treatment resulted in the activation of PPARγ coactivator 1-alpha (PGC-1α), a factor related to UCP1 transcription and mitochondrial biogenesis. Moreover, the expression of beige adipocyte-specific genes such as Cd137, Cited1, Tbx1, and Tmem26 was also induced. The small multi-lipid droplets characteristic of beige adipocytes indicated that naringin treatment increased the levels of all lipolysis markers (hormone-sensitive lipase [HSL], adipose triglyceride lipase [ATGL], perilipin [PLIN], and protein kinase A [PKA]). Adenosine monophosphate-activated protein kinase (AMPK) and UCP1 levels increased by treatment with naringin alone; this was possibly mediated by the stimulation of the AMPK signaling pathway. According to mechanistic studies, naringin activated the thermogenic protein UCP1 via the AMPK signaling pathway. In conclusion, naringin induces fat browning and is a promising therapeutic agent for metabolic disorders based on the regulation of lipid metabolism.

A Review of Structural Features, Biological Functions and Biotransformation Studies in Adipose Tissues and an Assessment of Progress and Implications

Roles for adipose tissues in energy metabolism, health maintenance and disease onset have been established. Evidence indicates that white, brown and beige fats are quite different in terms of their cellular origin and biological characteristics. These differences are significant in targeting adipocytes to study the pathogenesis and prevention strategies of related diseases. The biotransformations of white, brown and beige fat cells constitute an intriguing topic worthy of further study, and the molecular mechanisms underlying the biotransformations of white, brown and beige fat cells remain to be elucidated. Hence, we herein collected evidence from studies on adipose tissue or adipocytes, and we extracted the structural features, biologic functions, and biotransformations of adipose tissue/adipocytes. The present review aimed to summarize the latest research progress and propose novel research directions with respect to adipose tissue and adipocytes. We posit that this work will provide new insights and opportunities in the effective treatment strategies for obesity, diabetes and other lipid-related diseases. It will also contribute to our knowledge of the basic biologic underpinnings of adipocyte biology.

Adipose tissue aging is regulated by an altered immune system

Adipose tissue is a widely distributed organ that plays a critical role in age-related physiological dysfunctions as an important source of chronic sterile low-grade inflammation. Adipose tissue undergoes diverse changes during aging, including fat depot redistribution, brown and beige fat decrease, functional decline of adipose progenitor and stem cells, senescent cell accumulation, and immune cell dysregulation. Specifically, inflammaging is common in aged adipose tissue. Adipose tissue inflammaging reduces adipose plasticity and pathologically contributes to adipocyte hypertrophy, fibrosis, and ultimately, adipose tissue dysfunction. Adipose tissue inflammaging also contributes to age-related diseases, such as diabetes, cardiovascular disease and cancer. There is an increased infiltration of immune cells into adipose tissue, and these infiltrating immune cells secrete proinflammatory cytokines and chemokines. Several important molecular and signaling pathways mediate the process, including JAK/STAT, NFκB and JNK, etc. The roles of immune cells in aging adipose tissue are complex, and the underlying mechanisms remain largely unclear. In this review, we summarize the consequences and causes of inflammaging in adipose tissue. We further outline the cellular/molecular mechanisms of adipose tissue inflammaging and propose potential therapeutic targets to alleviate age-related problems.

Alternative Methods as Tools for Obesity Research: In Vitro and In Silico Approaches

The study of adipogenesis is essential for understanding and treating obesity, a multifactorial problem related to body fat accumulation that leads to several life-threatening diseases, becoming one of the most critical public health problems worldwide. In this review, we propose to provide the highlights of the adipogenesis study based on in vitro differentiation of human mesenchymal stem cells (hMSCs). We list in silico methods, such as molecular docking for identification of molecular targets, and in vitro approaches, from 2D, more straightforward and applied for screening large libraries of substances, to more representative physiological models, such as 3D and bioprinting models. We also describe the development of physiological models based on microfluidic systems applied to investigate adipogenesis in vitro. We intend to identify the main alternative models for adipogenesis evaluation, contributing to the direction of preclinical research in obesity. Future directions indicate the association of in silico and in vitro techniques to bring a clear picture of alternative methods based on adipogenesis as a tool for obesity research.

Angiogenesis-Browning Interplay Mediated by Asprosin-Knockout Contributes to Weight Loss in Mice with Obesity

Asprosin (ASP) is a recently identified adipokine secreted by white adipose tissue (WAT). It plays important roles in the maintenance of glucose homeostasis in the fasting state and in the occurrence and development of obesity. However, there is no report on whether and how ASP would inhibit angiogenesis and fat browning in the mouse adipose microenvironment. Therefore, the study sought to investigate the effects of ASP-knockout on angiogenesis and fat browning, and to identify the interaction between them in the ASP-knockout mouse adipose microenvironment. In the experiments in vivo, the ASP-knockout alleviated the obesity induced by a high fat diet (HFD) and increased the expressions of the browning-related proteins including uncoupling protein 1 (UCP1), PRD1-BF-1-RIZ1 homologus domain-containing protein-16 (PRDM16) and PPAR gamma coactivator 1 (PGC1-α) and the endothelial cell marker (CD31). In the experiments in vitro, treatment with the conditional medium (CM) from ASP-knockout adipocytes (ASP-/--CM) significantly promoted the proliferation, migration and angiogenesis of vascular endothelial cells, and increased the expressions of vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor 2 (VEGFR2) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/endothelial nitric oxide synthase (eNOS) pathway proteins. In addition, the treatment with CM from endothelial cells (EC-CM) markedly reduced the accumulation of lipid droplets and increased the expressions of the browning-related proteins and the mitochondrial contents. Moreover, the treatment with EC-CM significantly improved the energy metabolism in 3T3-L1 adipocytes. These results highlight that ASP-knockout can promote the browning and angiogenesis of WAT, and the fat browning and angiogenesis can interact in the mouse adipose microenvironment, which contributes to weight loss in the mice with obesity.

Dysfunction of insulin-AKT-UCP1 signalling inhibits transdifferentiation of human and mouse white preadipocytes into brown-like adipocytes

The mechanism of insulin signaling on browning of white preadipocytes remains unclear. Human and mouse primary subcutaneous white preadipocytes (hsASCs and WT lean and obese msASCs, respectively) were induced to transdifferentiate into beige adipocytes under conditions of intact or blocked insulin signaling, respectively. Level of phosphoinositide-3-kinase (PI3K) after induction of beige adipocytes under conditions of normal insulin signaling, phosphorylated protein kinase B (pAKT), peroxisome proliferator-activated receptor γ coactivator-1 alpha (PGC-1α), zinc-fifinger transcriptional factor PRD1-BF1-RIZ1 homologous domain-containing protein 16 (PRDM16), uncoupling protein 1 (UCP1), peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer binding protein beta (C/EBPβ) were significantly increased. Conversely, when insulin signaling is incompletely inhibited, the expression of the thermogenic and adipogenic factors is significantly reduced, with obvious impairment of adipogenesis. However, phosphorylation level of adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) and expression level of sirtuin type 1 (SIRT1) had increased. These white preadipocytes from different donors showed similar dynamic change in morphology and molecular levels during the browning. The present data indicate that insulin signaling plays a important role in regulation of browning of hsASCs and msASCs through PI3K-AKT-UCP1 signaling pathway. The insulin-AMPK-SIRT1 pathway was also involved in the adipocytes browning, while its effect is limited.

Role of Adipose Tissue microRNAs in the Onset of Metabolic Diseases and Implications in the Context of the DOHaD

The worldwide epidemic of obesity is associated with numerous comorbid conditions, including metabolic diseases such as insulin resistance and diabetes, in particular. The situation is likely to worsen, as the increase in obesity rates among children will probably lead to an earlier onset and more severe course for metabolic diseases. The origin of this earlier development of obesity may lie in both behavior (changes in nutrition, physical activity, etc.) and in children's history, as it appears to be at least partly programmed by the fetal/neonatal environment. The concept of the developmental origin of health and diseases (DOHaD), involving both organogenesis and epigenetic mechanisms, encompasses such programming. Epigenetic mechanisms include the action of microRNAs, which seem to play an important role in adipocyte functions. Interestingly, microRNAs seem to play a particular role in propagating local insulin resistance to other key organs, thereby inducing global insulin resistance and type 2 diabetes. This propagation involves the active secretion of exosomes containing microRNAs by adipocytes and adipose tissue-resident macrophages, as well as long-distance communication targeting the muscles and liver, for example. Circulating microRNAs may also be useful as biomarkers for the identification of populations at risk of subsequently developing obesity and metabolic diseases.

Browning of the white adipose tissue regulation: new insights into nutritional and metabolic relevance in health and diseases

Adipose tissues are dynamic tissues that play crucial physiological roles in maintaining health and homeostasis. Although white adipose tissue and brown adipose tissue are currently considered key endocrine organs, they differ functionally and morphologically. The existence of the beige or brite adipocytes, cells displaying intermediary characteristics between white and brown adipocytes, illustrates the plastic nature of the adipose tissue. These cells are generated through white adipose tissue browning, a process associated with augmented non-shivering thermogenesis and metabolic capacity. This process involves the upregulation of the uncoupling protein 1, a molecule that uncouples the respiratory chain from Adenosine triphosphate synthesis, producing heat. β-3 adrenergic receptor system is one important mediator of white adipose tissue browning, during cold exposure. Surprisingly, hyperthermia may also induce beige activation and white adipose tissue beiging. Physical exercising copes with increased levels of specific molecules, including Beta-Aminoisobutyric acid, irisin, and Fibroblast growth factor 21 (FGF21), which induce adipose tissue browning. FGF21 is a stress-responsive hormone that interacts with beta-klotho. The central roles played by hormones in the browning process highlight the relevance of the individual lifestyle, including circadian rhythm and diet. Circadian rhythm involves the sleep-wake cycle and is regulated by melatonin, a hormone associated with UCP1 level upregulation. In contrast to the pro-inflammatory and adipose tissue disrupting effects of the western diet, specific food items, including capsaicin and n-3 polyunsaturated fatty acids, and dietary interventions such as calorie restriction and intermittent fasting, favor white adipose tissue browning and metabolic efficiency. The intestinal microbiome has also been pictured as a key factor in regulating white tissue browning, as it modulates bile acid levels, important molecules for the thermogenic program activation. During embryogenesis, in which adipose tissue formation is affected by Bone morphogenetic proteins that regulate gene expression, the stimuli herein discussed influence an orchestra of gene expression regulators, including a plethora of transcription factors, and chromatin remodeling enzymes, and non-coding RNAs. Considering the detrimental effects of adipose tissue browning and the disparities between adipose tissue characteristics in mice and humans, further efforts will benefit a better understanding of adipose tissue plasticity biology and its applicability to managing the overwhelming burden of several chronic diseases.

Novel Plant Extract Ameliorates Metabolic Disorder through Activation of Brown Adipose Tissue in High-Fat Diet-Induced Obese Mice

Obesity is characterized by excessive body fat accumulation due to unbalanced energy intake and expenditure. Potential therapeutic targets for anti-obesity include the inhibition of white adipose tissue (WAT) hypertrophy and hyperplasia and the activation of brown adipose tissue (BAT). Not only the activation of BAT but also the browning of WAT have gained increasing attention in research fields as an alternative method in the prevention and treatment of obesity. Here, we investigated possible mechanisms underlying the anti-obesity effect of Phlomis umbrosa Turcz. root ethanol extract (PUE) in an obesogenic animal model. PUE treatment can reduce diet-induced obesity and modulate obesity-associated metabolic disorders, including insulin resistance, hepatic steatosis, and inflammation. In the liver, PUE improved hepatic steatosis by suppressing hepatic lipogenesis and lipid absorption while increasing biliary sterol excretion and hepatic fatty acid oxidation compared to the high-fat group. Moreover, PUE increased energy expenditure and regulated fecal lipid excretion, leading to reduced body weight gain. In particular, PUE remarkably activated the browning of subWAT via upregulation of the browning-related protein and gene expression and promoted BAT activation. In conclusion, these findings provide the potential therapeutic usefulness into the effects of PUE in the treatment of obesity and metabolic disorders. Furthermore, it suggests that PUE treatment can regulate energy metabolism via activating BAT and browning subWAT.

RNA-Binding Proteins in the Regulation of Adipogenesis and Adipose Function

The obesity epidemic represents a critical public health issue worldwide, as it is a vital risk factor for many diseases, including type 2 diabetes (T2D) and cardiovascular disease. Obesity is a complex disease involving excessive fat accumulation. Proper adipose tissue accumulation and function are highly transcriptional and regulated by many genes. Recent studies have discovered that post-transcriptional regulation, mainly mediated by RNA-binding proteins (RBPs), also plays a crucial role. In the lifetime of RNA, it is bound by various RBPs that determine every step of RNA metabolism, from RNA processing to alternative splicing, nucleus export, rate of translation, and finally decay. In humans, it is predicted that RBPs account for more than 10% of proteins based on the presence of RNA-binding domains. However, only very few RBPs have been studied in adipose tissue. The primary aim of this paper is to provide an overview of RBPs in adipogenesis and adipose function. Specifically, the following best-characterized RBPs will be discussed, including HuR, PSPC1, Sam68, RBM4, Ybx1, Ybx2, IGF2BP2, and KSRP. Characterization of these proteins will increase our understanding of the regulatory mechanisms of RBPs in adipogenesis and provide clues for the etiology and pathology of adipose-tissue-related diseases.

Nidus vespae Built by an Invasive Alien Hornet, Vespa velutina nigrithorax, Inhibits Adipose Tissue Expansion in High-Fat Diet-Induced Obese Mice

Nidus vespae, commonly known as the wasp nest, has antioxidative, anti-inflammatory, antimicrobial, and antitumor properties. However, the anti-obesity effects of Nidus vespae extract (NV) have not yet been reported. This study aimed to elucidate the potential anti-obesity effects of NV in vivo and in vitro, using a high-fat diet (HFD)-induced obese mouse model and 3T3-L1 adipocytes, respectively. NV administration to HFD-induced obese mice significantly decreased the mass and plasma lipid content of adipose tissues. Uncoupling protein-1 expression was significantly higher in the inguinal white adipose tissues of NV-treated mice than in those of HFD-fed mice. Furthermore, we found that NV inhibited the differentiation and intracellular lipid accumulation of 3T3-L1 adipocytes by regulating the insulin signaling cascade, including protein kinase B, peroxisome proliferator-activated receptor gamma, CCAAT/enhancer binding protein alpha, and adiponectin. These findings suggest that NV may exhibit therapeutic effects against obesity by suppressing adipose tissue expansion and preadipocyte differentiation, thereby providing critical information for the development of new drugs for disease prevention and treatment. To our knowledge, this study provides the first evidence of the anti-obesity effects of NV.

Intraosseous hibernoma: Two case reports and a review of the literature

Intraosseous hibernomas are exceedingly rare tumors with only 35 cases reported worldwide. They are composed of vestigial brown adipose tissue and require biopsy and pathologic analysis for definitive diagnosis. Given their propensity to mimic more insidious malignant neoplasms, early and accurate identification may spare the patient both anxiety and invasive therapeutic interventions. In this report, we present two cases of intraosseous hibernomas and provide a review of current literature to further characterize the clinical, radiographic, and histopathologic parameters of these lesions. Clinicians should consider the diagnosis of intraosseous hibernoma when evaluating patients with characteristic presentations as it may be more prevalent than currently reported.

The distinct phenotype of primary adipocytes and adipocytes derived from stem cells of white adipose tissue as assessed by Raman and fluorescence imaging

Spectroscopy-based analysis of chemical composition of cells is a tool still scarcely used in biological sciences, although it provides unique information about the cell identity accessible in vivo and in situ. Through time-lapse spectroscopic monitoring of adipogenesis in brown and white adipose tissue-derived stem cells we have demonstrated that considerable chemical and functional changes occur along with cells differentiation and maturation, yet yielding mature adipocytes with a similar chemical composition, independent of the cellular origin (white or brown adipose tissue). However, in essence, these stem cell-derived adipocytes have a markedly different chemical composition compared to mature primary adipocytes. The consequences of this different chemical (and, hence, functional) identity have great importance in the context of selecting a suitable methodology for adipogenesis studies, particularly in obesity-related research.

Targeting of the Peritumoral Adipose Tissue Microenvironment as an Innovative Antitumor Therapeutic Strategy

The tumor microenvironment (TME) plays a key role in promoting and sustaining cancer growth. Adipose tissue (AT), due to its anatomical distribution, is a prevalent component of TME, and contributes to cancer development and progression. Cancer-associated adipocytes (CAAs), reprogrammed by cancer stem cells (CSCs), drive cancer progression by releasing metabolites and inflammatory adipokines. In this review, we highlight the mechanisms underlying the bidirectional crosstalk among CAAs, CSCs, and stromal cells. Moreover, we focus on the recent advances in the therapeutic targeting of adipocyte-released factors as an innovative strategy to counteract cancer progression.

Many Ways to Rome: Exercise, Cold Exposure and Diet-Do They All Affect BAT Activation and WAT Browning in the Same Manner?

The discovery of functional brown adipose tissue (BAT) in adult humans and the possibility to recruit beige cells with high thermogenic potential within white adipose tissue (WAT) depots opened the field for new strategies to combat obesity and its associated comorbidities. Exercise training as well as cold exposure and dietary components are associated with the enhanced accumulation of metabolically-active beige adipocytes and BAT activation. Both activated beige and brown adipocytes increase their metabolic rate by utilizing lipids to generate heat via non-shivering thermogenesis, which is dependent on uncoupling protein 1 (UCP1) in the inner mitochondrial membrane. Non-shivering thermogenesis elevates energy expenditure and promotes a negative energy balance, which may ameliorate metabolic complications of obesity and Type 2 Diabetes Mellitus (T2DM) such as insulin resistance (IR) in skeletal muscle and adipose tissue. Despite the recent advances in pharmacological approaches to reduce obesity and IR by inducing non-shivering thermogenesis in BAT and WAT, the administered pharmacological compounds are often associated with unwanted side effects. Therefore, lifestyle interventions such as exercise, cold exposure, and/or specified dietary regimens present promising anchor points for future disease prevention and treatment of obesity and T2DM. The exact mechanisms where exercise, cold exposure, dietary interventions, and pharmacological treatments converge or rather diverge in their specific impact on BAT activation or WAT browning are difficult to determine. In the past, many reviews have demonstrated the mechanistic principles of exercise- and/or cold-induced BAT activation and WAT browning. In this review, we aim to summarize not only the current state of knowledge on the various mechanistic principles of diverse external stimuli on BAT activation and WAT browning, but also present their translational potential in future clinical applications.

Preventing White Adipocyte Browning during Differentiation In Vitro: The Effect of Differentiation Protocols on Metabolic and Mitochondrial Phenotypes

Mitochondrial dysfunction in white adipose tissue is strongly associated with obesity and its metabolic complications, which are important health challenges worldwide. Human adipose-derived stromal/stem cells (hASCs) are a promising tool to investigate the underlying mechanisms of such mitochondrial dysfunction and to subsequently provide knowledge for the development of treatments for obesity-related pathologies. A substantial obstacle in using hASCs is that the key compounds for adipogenic differentiation in vitro increase mitochondrial uncoupling, biogenesis, and activity, which are the signature features of brown adipocytes, thus altering the white adipocyte phenotype towards brown-like cells. Additionally, commonly used protocols for hASC adipogenic differentiation exhibit high variation in their composition of media, and a systematic comparison of their effect on mitochondria is missing. Here, we compared the five widely used adipogenic differentiation protocols for their effect on metabolic and mitochondrial phenotypes to identify a protocol that enables in vitro differentiation of white adipocytes and can more faithfully recapitulate the white adipocyte phenotype observed in human adipose tissue. We developed a workflow that included functional assays and morphological analysis of mitochondria and lipid droplets. We observed that triiodothyronine- or indomethacin-containing media and commercially available adipogenic media induced browning during in vitro differentiation of white adipocytes. However, the differentiation protocol containing 1 μM of the peroxisome proliferator-activated receptor gamma (PPARγ) agonist rosiglitazone prevented the browning effect and would be proposed for adipogenic differentiation protocol for hASCs to induce a white adipocyte phenotype. Preserving the white adipocyte phenotype in vitro is a crucial step for the study of obesity and associated metabolic diseases, adipose tissue pathologies, such as lipodystrophies, possible therapeutic compounds, and basic adipose tissue physiology.

Melatonin induces fat browning by transdifferentiation of white adipocytes and de novo differentiation of mesenchymal stem cells

The role of melatonin in obesity control is extensively accepted, but its mechanism of action is still unclear. Previously we demonstrated that chronic oral melatonin acts as a brown-fat inducer, driving subcutaneous white adipose tissue (sWAT) into a brown-fat-like function (beige) in obese diabetic rats. However, immunofluorescence characterization of beige depots in sWAT and whether melatonin is a beige-fat inducer by de novo differentiation and/or transdifferentiation of white adipocytes are still undefined. Lean (ZL) and diabetic fatty (ZDF) Zücker rats were subdivided into two groups, control (C) and oral melatonin-supplemented (M, 10 mg kg^-1 day^-1) for 6 weeks. Mesenchymal stem cells (MSCs) were isolated from both rat inguinal fat and human lipoaspirates followed by adipogenesis assays with or without melatonin (50 nM for 12 h in a 24 h period, 12 h+/12 h-) mimicking the light/dark cycle. Immunofluorescence and western-blot assays showed the partial transdifferentiation of white adipocytes in both ZL and ZDF rats, with increasing thermogenic and beige markers, UCP1 and CITED1 and decreasing white adipocyte marker ASC-1 expression. In addition, melatonin increased UCP1, CITED1, and PGC1-α expression in differentiated adipocytes in both rats and humans. These results demonstrate that melatonin increases brown fat in obese diabetic rats by both adipocyte transdifferentiation and de novo differentiation. Furthermore, it promotes beige MSC adipogenesis in humans. This may contribute to the control of body weight attributed to melatonin and its metabolic benefits in human diabesity.

White, beige and brown adipose tissue: structure, function, specific features and possibility formation and divergence in pigs

Introduction. Traditionally, mammalian adipose tissue is divided into white (white adipose tissue – WAT) and brown (brown adipose tissue – BAT). While the functions of WAT are well known as the triglyceride depot, the role of BAT in mammalian physiology has been under close investigation. The first description of the role of BAT in maintaining thermogenesis dates back to 1961. This article offers a review of structural and functional specificity of white, beige and brown adipose tissue. Results and discussion. The differences and descriptions of adipocytes and their impact on the maintenance of the main functions of the mammalian body are described in this manuscript. In particular, thermogenesis, stress response, obesity, type II diabetes. In addition to WAT and BAT, an intermediate form was also detected in the body – beige fat (BeAT or Brite). The opposite opinions regarding the presence of three types of adipose tissue in the human and animal bodies are presented. Studies on the identification of uncoupling proteins 1 and 3 and their role in the transformation of white fat into beige/brown are considered. Basically, the data on the factors of endogenous and exogenous nature on their formation are given on the example of the human body. Conclusion. With an abundance of publications on the keywords: “white, brown fat”, these studies, in the overwhelming majority, are devoted to the role of these fats in the formation of human thermogenesis, the assessment of the impact on obesity. Pigs have also been suggested to lack functional BAT, which is a major cause of neonatal death in the swine industry, therefore the focus on investigating role of different types of adipose tissue in pigs seems very promising in order to understand whether there is a compensating mechanism of thermogenesis.

The integrin beta1 modulator Tirofiban prevents adipogenesis and obesity by the overexpression of integrin-linked kinase: a pre-clinical approach in vitro and in vivo

Background

Obesity is caused by the enlargement of the white adipose tissue (WAT) depots, characterized by the hypertrophic enlargement of malfunctioning adipocytes within WAT which increases the storage of triglycerides (TG) in the lipid droplets (LD). Adipogenesis pathways as well as the expression and activity of some extracellular matrix receptors integrins are upregulated. Integrinβ1 (INTB1) is the main isoform involved in WAT remodeling during obesity and insulin resistance-related diseases. We recently described Integrin Linked Kinase (ILK), a scaffold protein recruited by INTB1, as an important mediator of WAT remodeling and insulin resistance. As the few approved drugs to fight obesity have brought long-term cardiovascular side effects and given that the consideration of INTB1 and/or ILK modulation as anti-obesogenic strategies remains unexplored, we aimed to evaluate the anti-obesogenic capacity of the clinically approved anticoagulant Tirofiban (TF), stated in preclinical studies as a cardiovascular protector.

Methods

Fully differentiated adipocytes originating from C3H10T1/2 were exposed to TF and were co-treated with specific INTB1 blockers or with siRNA-based knockdown ILK expression. Lipid-specific dyes were used to determine the TG content in LD. The genetic expression pattern of ILK, pro-inflammatory cytokines (MCP1, IL6), adipogenesis (PPARγ, Leptin), thermogenesis (UCP1), proliferation (PCNA), lipid metabolism (FASN, HSL, ATGL), and metabolite transporters (FABP4, FAT, AQP7) were detected using quantitative PCR. Cytoskeletal actin polymerization was detected by confocal microscopy. Immunoblotting was performed to detect INTB1 phosphorylation at Thr788/9 and ILK activity as phosphorylation levels of protein kinase B (AKT) in Ser473 and glycogen synthase kinase 3β (GSK3β) at Ser9. TF was intraperitoneally administered once per day to wildtype and ILK knockdown mice (cKDILK) challenged with a high-fat diet (HFD) or control diet (STD) for 2 weeks. Body and WAT weight gains were compared. The expression of ILK and other markers was determined in the visceral epididymal (epi) and inguinal subcutaneous (sc) WAT.

Results

TF reduced TG content and the expression of adipogenesis markers and transporters in adipocytes, while UCP-1 expression was increased and the expression of lipases, cytokines or PCNA was not affected. Mechanistically, TF rapidly increased and faded the intracellular phosphorylation of INTB1 but not AKT or GSK3β. F-actin levels were rapidly decreased, and INTB1 blockade avoided the TF effect. After 24 h, ILK expression and phosphorylation rates of AKT and GSK3β were upregulated, while ILK silencing increased TG content. INTB1 blockade and ILK silencing avoided TF effects on the TG content and the transcriptional expression of PPARγ and UCP1. In HFD-challenged mice, the systemic administration of TF for several days reduced the weight gain on WAT depots. TF reduced adipogenesis and pro-inflammatory biomarkers and increased lipolysis markers HSL and FAT in epiWAT from HFD, while increased UCP1 in scWAT. In both WATs, TF upregulated ILK expression and activity, while no changes were observed in other tissues. In HFD-fed cKDILK, the blunted ILK in epiWAT worsened weight gain and avoided the anti-obesogenic effect of in vivo TF administration.

Conclusions

ILK downregulation in WAT can be considered a biomarker of obesity establishment. Via an INTB1-ILK axis, TF restores malfunctioning hypertrophied WAT by changing the expression of adipocyte-related genes, increasing ILK expression and activity, and reducing TG storage. TF prevents obesity, a property to be added to its anticoagulant and cardiovascular protective advantages.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00746-1.

Role of lncRNAs into Mesenchymal Stromal Cell Differentiation

Currently, findings support that 75% of the human genome is actively transcribed, but only 2% is translated into a protein, according to databases such as ENCODE (Encyclopedia of DNA Elements) [1]. The development of high-throughput sequencing technologies, computational methods for genome assembly and biological models have led to the realization of the importance of the previously unconsidered non-coding fraction of the genome. Along with this, noncoding RNAs have been shown to be epigenetic, transcriptional and post-transcriptional regulators in a large number of cellular processes [2]. Within the group of non-coding RNAs, lncRNAs represent a fascinating field of study, given the functional versatility in their mode of action on their molecular targets. In recent years, there has been an interest in learning about lncRNAs in MSC differentiation. The aim of this review is to address the signaling mechanisms where lncRNAs are involved, emphasizing their role in either stimulating or inhibiting the transition to differentiated cell. Specifically, the main types of MSC differentiation are discussed: myogenesis, osteogenesis, adipogenesis and chondrogenesis. The description of increasingly new lncRNAs reinforces their role as players in the well-studied field of MSC differentiation, allowing a step towards a better understanding of their biology and their potential application in the clinic.