Plasminogen activator inhibitor-1 modulates adipocyte differentiation

SERPINE1AS2 regulates intramuscular adipogenesis by inhibiting PAI1 protein expression

Antisense long non-coding RNAs (lncRNAs) played a crucial role in the precise regulation of essential biological processes and were abundantly present in animals. Many of these antisense lncRNAs have been identified as key roles in adipose tissue accumulation in livestock, underscoring their vital role in the regulation of animal physiology. Nonetheless, the functional roles of these antisense lncRNAs in regulating adipogenesis and the specific molecular mechanisms these processes were still unclear, which was a significant gap in current scientific research. In this study, we identified and characterized SERPINE1AS2, a novel natural antisense lncRNA, was highly expressed in the fat tissues of adult cattle and calves. Its expression gradually increased during the differentiation of intramuscular adipocytes. Through functional studies, we observed that knockdown of SERPINE1AS2 inhibited the proliferation and adipogenesis of intramuscular adipocytes, while overexpression of SERPINE1AS2 produced the opposite effect. RNA sequencing (RNA-seq) analysis following SERPINE1AS2 knockdown revealed that differential expression genes (DEGs) were significantly enriched in key signaling pathways, notably the MAPK, Wnt, and mTOR signaling pathways. Furthermore, SERPINE1AS2 interacted with Plasminogen Activator Inhibitor-1 (PAI1), forming RNA dimers through complementary base pairing and consequently influencing PAI1 expression. Interestingly, studies on PAI1 suggested that reduced expression facilitated adipogenesis and the downregulation of PAI1 alleviated the inhibitory effect of reduced SERPINE1AS2 on adipogenesis. In summary, this study suggested that SERPINE1AS2 played a crucial role in the adipogenesis of bovine intramuscular adipocytes by modulating the expression of PAI1. SERPINE1AS2 also regulated adipogenesis by engaging in the MAPK, Wnt, and mTOR signaling pathways. Our results suggested that SERPINE1AS2 had a complex regulatory mechanism on adipogenesis in intramuscular adipocytes.

Reappraisal of Adipose Tissue Inflammation in Obesity

Chronic low-grade inflammation is a central component in the pathogenesis of obesity-related expansion of adipose tissue and complications in other metabolic tissues. Five different signaling pathways are defined as dominant determinants of adipose tissue inflammation: These are increased circulating endotoxin due to dysregulation in the microbiota-gut-brain axis, systemic oxidative stress, macrophage accumulation, and adipocyte death. Finally, the nucleotide-binding and oligomerization domain (NOD) leucine-rich repeat family pyrin domain-containing 3 (NLRP3) inflammasome pathway is noted to be a key regulator of metabolic inflammation. The NLRP3 inflammasome and associated metabolic inflammation play an important role in the relationships among fatty acids and obesity. Several highly active molecules, including primarily leptin, resistin, adiponectin, visfatin, and classical cytokines, are abundantly released from adipocytes. The most important cytokines that are released by inflammatory cells infiltrating obese adipose tissue are tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), monocyte chemoattractant protein 1 (MCP-1) (CCL-2), and IL-1. All these molecules mentioned above act on immune cells, causing local and then general inflammation. Three metabolic pathways are noteworthy in the development of adipose tissue inflammation: toll-like receptor 4 (TLR4)/phosphatidylinositol-3'-kinase (PI3K)/Protein kinase B (Akt) signaling pathway, endoplasmic reticulum (ER) stress-derived unfolded protein response (UPR), and inhibitor of nuclear factor kappa-B kinase beta (IKKβ)-nuclear factor kappa B (NF-κB) pathway. In fact, adipose tissue inflammation is an adaptive response that contributes to a visceral depot barrier that effectively filters gut-derived endotoxin. Excessive fatty acid release worsens adipose tissue inflammation and contributes to insulin resistance. However, suppression of adipose inflammation in obesity with anti-inflammatory drugs is not a rational solution and paradoxically promotes insulin resistance, despite beneficial effects on weight gain. Inflammatory pathways in adipocytes are indeed indispensable for maintaining systemic insulin sensitivity. Cannabinoid type 1 receptor (CB1R) is important in obesity-induced pro-inflammatory response; however, blockade of CB1R, contrary to anti-inflammatory drugs, breaks the links between insulin resistance and adipose tissue inflammation. Obesity, however, could be decreased by improving leptin signaling, white adipose tissue browning, gut microbiota interactions, and alleviating inflammation. Furthermore, capsaicin synthesized by chilies is thought to be a new and promising therapeutic option in obesity, as it prevents metabolic endotoxemia and systemic chronic low-grade inflammation caused by high-fat diet.

Adipokines and Bacterial Metabolites: A Pivotal Molecular Bridge Linking Obesity and Gut Microbiota Dysbiosis to Target

Adipokines are essential mediators produced by adipose tissue and exert multiple biological functions. In particular, adiponectin, leptin, resistin, IL-6, MCP-1 and PAI-1 play specific roles in the crosstalk between adipose tissue and other organs involved in metabolic, immune and vascular health. During obesity, adipokine imbalance occurs and leads to a low-grade pro-inflammatory status, promoting insulin resistance-related diabetes and its vascular complications. A causal link between obesity and gut microbiota dysbiosis has been demonstrated. The deregulation of gut bacteria communities characterizing this dysbiosis influences the synthesis of bacterial substances including lipopolysaccharides and specific metabolites, generated via the degradation of dietary components, such as short-chain fatty acids, trimethylamine metabolized into trimethylamine-oxide in the liver and indole derivatives. Emerging evidence suggests that these bacterial metabolites modulate signaling pathways involved in adipokine production and action. This review summarizes the current knowledge about the molecular links between gut bacteria-derived metabolites and adipokine imbalance in obesity, and emphasizes their roles in key pathological mechanisms related to oxidative stress, inflammation, insulin resistance and vascular disorder. Given this interaction between adipokines and bacterial metabolites, the review highlights their relevance (i) as complementary clinical biomarkers to better explore the metabolic, inflammatory and vascular complications during obesity and gut microbiota dysbiosis, and (ii) as targets for new antioxidant, anti-inflammatory and prebiotic triple action strategies.

A single-cell CRISPRi platform for characterizing candidate genes relevant to metabolic disorders in human adipocytes

CROP-Seq combines gene silencing using CRISPR interference with single-cell RNA sequencing. Here, we applied CROP-Seq to study adipogenesis and adipocyte biology. Human preadipocyte SGBS cell line expressing KRAB-dCas9 was transduced with a sgRNA library. Following selection, individual cells were captured using microfluidics at different timepoints during adipogenesis. Bioinformatic analysis of transcriptomic data was used to determine the knockdown effects, the dysregulated pathways, and to predict cellular phenotypes. Single-cell transcriptomes recapitulated adipogenesis states. For all targets, over 400 differentially expressed genes were identified at least at one timepoint. As a validation of our approach, the knockdown of PPARG and CEBPB (which encode key proadipogenic transcription factors) resulted in the inhibition of adipogenesis. Gene set enrichment analysis generated hypotheses regarding the molecular function of novel genes. MAFF knockdown led to downregulation of transcriptional response to proinflammatory cytokine TNF-α in preadipocytes and to decreased CXCL-16 and IL-6 secretion. TIPARP knockdown resulted in increased expression of adipogenesis markers. In summary, this powerful, hypothesis-free tool can identify novel regulators of adipogenesis, preadipocyte, and adipocyte function associated with metabolic disease.NEW & NOTEWORTHY Genomics efforts led to the identification of many genomic loci that are associated with metabolic traits, many of which are tied to adipose tissue function. However, determination of the causal genes, and their mechanism of action in metabolism, is a time-consuming process. Here, we use an approach to determine the transcriptional outcome of candidate gene knockdown for multiple genes at the same time in a human cell model of adipogenesis.

The Role of Obesity in Breast Cancer Pathogenesis

Research has shown that obesity increases the risk for type 2 diabetes mellitus (Type 2 DM) by promoting insulin resistance, increases serum estrogen levels by the upregulation of aromatase, and promotes the release of reactive oxygen species (ROS) by macrophages. Increased circulating glucose has been shown to activate mammalian target of rapamycin (mTOR), a significant signaling pathway in breast cancer pathogenesis. Estrogen plays an instrumental role in estrogen-receptor-positive breast cancers. The role of ROS in breast cancer warrants continued investigation, in relation to both pathogenesis and treatment of breast cancer. We aim to review the role of obesity in breast cancer pathogenesis and novel therapies mediating obesity-associated breast cancer development. We explore the association between body mass index (BMI) and breast cancer incidence and the mechanisms by which oxidative stress modulates breast cancer pathogenesis. We discuss the role of glutathione, a ubiquitous antioxidant, in breast cancer therapy. Lastly, we review breast cancer therapies targeting mTOR signaling, leptin signaling, blood sugar reduction, and novel immunotherapy targets.

1,3-Butanediol Administration Increases β-Hydroxybutyrate Plasma Levels and Affects Redox Homeostasis, Endoplasmic Reticulum Stress, and Adipokine Production in Rat Gonadal Adipose Tissue

Ketone bodies (KBs) are an alternative energy source under starvation and play multiple roles as signaling molecules regulating energy and metabolic homeostasis. The mechanism by which KBs influence visceral white adipose tissue physiology is only partially known, and our study aimed to shed light on the effects they exert on such tissue. To this aim, we administered 1,3-butanediol (BD) to rats since it rapidly enhances β-hydroxybutyrate serum levels, and we evaluated the effect it induces within 3 h or after 14 days of treatment. After 14 days of treatment, rats showed a decrease in body weight gain, energy intake, gonadal-WAT (gWAT) weight, and adipocyte size compared to the control. BD exerted a pronounced antioxidant effect and directed redox homeostasis toward reductive stress, already evident within 3 h after its administration. BD lowered tissue ROS levels and oxidative damage to lipids and proteins and enhanced tissue soluble and enzymatic antioxidant capacity as well as nuclear erythroid factor-2 protein levels. BD also reduced specific mitochondrial maximal oxidative capacity and induced endoplasmic reticulum stress as well as interrelated processes, leading to changes in the level of adipokines/cytokines involved in inflammation, macrophage infiltration into gWAT, adipocyte differentiation, and lipolysis.

Melanoma cells induce dedifferentiation and metabolic changes in adipocytes present in the tumor niche

BACKGROUND

One of the factors that affect the progression of melanoma is the tumor microenvironment, which consists of cellular elements, extracellular matrix, acidification, and a hypoxic state. Adipocytes are one of the types of cell present in the niche and are localized in the deepest layer of the skin. However, the relationship between fat cells and melanoma remains unclear.

METHODS

We assessed the influence of melanoma cells on adipocytes using an indirect coculture system. We estimated the level of cancer-associated adipocyte (CAA) markers through quantitative PCR analysis. The fibroblastic phenotype of CAAs was confirmed by cell staining and western blotting analysis. The lipid content was estimated by lipid detection in CAAs using LipidSpot and by quantitative analysis using Oil Red O. The expression of proteins involved in lipid synthesis, delipidation, and metabolic processes were assessed through quantitative PCR or western blotting analysis. Lactate secretion was established using a Lactate-Glo™ assay. Proteins secreted by CAAs were identified in cytokine and angiogenesis arrays. The proliferation of melanoma cells cocultured with CAAs was assessed using an XTT proliferation assay. Statistical analysis was performed using a one-way ANOVA followed by Tukey's test in GraphPad Prism 7 software.

RESULTS

Obtained CAAs were identified by decreased levels of leptin, adiponectin, resistin, and FABP4. Adipocytes cocultured with melanoma presented fibroblastic features, such as a similar proteolytic pattern to that of 3T3L1 fibroblasts and increased levels of vimentin and TGFβRIII. Melanoma cells led to a reduction of lipid content in CAAs, possibly by downregulation of lipid synthesis pathways (lower FADS, SC4MOL, FASN) or enhancement of lipolysis (higher level of phosphorylation of ERK and STAT3). Adipocytes cocultured with melanoma cells secreted higher IL6 and SerpinE1 levels and produced less CCL2, CXCL1, and angiogenic molecules. CAAs also showed metabolic changes comprising the increased secretion of lactate and enhanced production of glucose, lactate, and ion transporters. In addition, changes in adipocytes observed following melanoma coculture resulted in a higher proliferation rate of cancer cells.

CONCLUSIONS

Melanoma cells led to decreased lipid content in adipocytes, which might be related to enhanced delipidation or reduction of lipid synthesis. Fibroblast-like CAAs showed metabolic changes that may be the reason for accelerated proliferation of melanoma cells.

Heterogeneity in the effect of marked weight loss on metabolic function in women with obesity

BACKGROUNDThere is considerable heterogeneity in the effect of weight loss on metabolic function in people with obesity.METHODSWe evaluated muscle and liver insulin sensitivity, body composition, and circulating factors associated with insulin action before and after approximately 20% weight loss in women identified as "Responders" (n = 11) or "Non-responders" (n = 11), defined as the top (>75% increase) and bottom (<5% increase) quartiles of the weight loss-induced increase in glucose disposal rate (GDR) during a hyperinsulinemic-euglycemic clamp procedure, among 43 women with obesity (BMI: 44.1 ± 7.9 kg/m2).RESULTSAt baseline, GDR, which provides an index of muscle insulin sensitivity, and the hepatic insulin sensitivity index were more than 50% lower in Responders than Non-responders, but both increased much more after weight loss in Responders than Non-responders, which eliminated the differences between groups. Weight loss also caused greater decreases in intrahepatic triglyceride content and plasma adiponectin and PAI-1 concentrations in Responders than Non-responders and greater insulin-mediated suppression of plasma free fatty acids, branched-chain amino acids, and C3/C5 acylcarnitines in Non-responders than Responders, so that differences between groups at baseline were no longer present after weight loss. The effect of weight loss on total body fat mass, intra-abdominal adipose tissue volume, adipocyte size, and circulating inflammatory markers were not different between groups.CONCLUSIONThe results from our study demonstrate that the heterogeneity in the effects of marked weight loss on muscle and hepatic insulin sensitivity in people with obesity is determined by baseline insulin action, and reaches a ceiling when "normal" insulin action is achieved.TRIAL REGISTRATIONNCT00981500, NCT01299519, NCT02207777.FUNDINGNIH grants P30 DK056341, P30 DK020579, P30 DK052574, UL1 TR002345, and T32 HL13035, the American Diabetes Association (1-18-ICTS-119), the Longer Life Foundation (2019-011), and the Atkins Philanthropic Trust.

The Role of Epicardial Adipose Tissue-Derived MicroRNAs in the Regulation of Cardiovascular Disease: A Narrative Review

Cardiovascular diseases have been leading cause of death worldwide for many decades, and obesity has been acknowledged as a risk factor for cardiovascular diseases. In the present review, human epicardial adipose tissue-derived miRNAs reported to be differentially expressed under pathologic conditions are discussed and summarized. The results of the literature review indicate that some of the epicardial adipose tissue-derived miRNAs are believed to be cardioprotective, while some others show quite the opposite effects depending on the underlying pathologic conditions. Furthermore, they suggest that that the epicardial adipose tissue-derived miRNAs have great potential as both a diagnostic and therapeutic modality. Nevertheless, mainly due to highly limited availability of human samples, it is very difficult to make any generalized claims on a given miRNA in terms of its overall impact on the cardiovascular system. Therefore, further functional investigation of a given miRNA including, but not limited to, the study of its dose effect, off-target effects, and potential toxicity is required. We hope that this review can provide novel insights to transform our current knowledge on epicardial adipose tissue-derived miRNAs into clinically viable therapeutic strategies for preventing and treating cardiovascular diseases.

Extracellular Matrix (ECM) and Fibrosis in Adipose Tissue: Overview and Perspectives

Fibrosis in adipose tissue is a major driver of obesity-related metabolic dysregulation. It is characterized by an overaccumulation of extracellular matrix (ECM) during unhealthy expansion of adipose tissue in response to over nutrition. In obese adipose-depots, hypoxia stimulates multiple pro-fibrotic signaling pathways in different cell populations, thereby inducing the overproduction of the ECM components, including collagens, noncollagenous proteins, and additional enzymatic components of ECM synthesis. As a consequence, local fibrosis develops. The result of fibrosis-induced mechanical stress not only triggers cell necrosis and inflammation locally in adipose tissue but also leads to system-wide lipotoxicity and insulin resistance. A better understanding of the mechanisms underlying the obesity-induced fibrosis will help design therapeutic approaches to reduce or reverse the pathological changes associated with obese adipose tissue. Here, we aim to summarize the major advances in the field, which include newly identified fibrotic factors, cell populations that contribute to the fibrosis in adipose tissue, as well as novel mechanisms underlying the development of fibrosis. We further discuss the potential therapeutic strategies to target fibrosis in adipose tissue for the treatment of obesity-linked metabolic diseases and cancer. © 2023 American Physiological Society. Compr Physiol 13:4387-4407, 2023.

Adipokines from white adipose tissue in regulation of whole body energy homeostasis

Diseases originating from altered energy homeostasis including obesity, and type 2 diabetes are rapidly increasing worldwide. Research in the last few decades on animal models and humans demonstrates that the white adipose tissue (WAT) is critical for energy balance and more than just an energy storage site. WAT orchestrates the whole-body metabolism through inter-organ crosstalk primarily mediated by cytokines named "Adipokines". The adipokines influence metabolism and fuel selection of the skeletal muscle and liver thereby fine-tuning the load on WAT itself in physiological conditions like starvation, exercise and cold. In addition, adipokine secretion is influenced by various pathological conditions like obesity, inflammation and diabetes. In this review, we have surveyed the current state of knowledge on important adipokines and their significance in regulating energy balance and metabolic diseases. Furthermore, we have summarized the interplay of pro-inflammatory and anti-inflammatory adipokines in the modulation of pathological conditions.

Adipose Tissue Development Relies on Coordinated Extracellular Matrix Remodeling, Angiogenesis, and Adipogenesis

Despite developing prenatally, the adipose tissue is unique in its ability to undergo drastic growth even after reaching its mature size. This development and subsequent maintenance rely on the proper coordination between the vascular niche and the adipose compartment. In this review, the process of adipose tissue development is broken down to explain (1) the ultrastructural matrix remodeling that is undertaken during simultaneous adipogenesis and angiogenesis, (2) the paracrine crosstalk involved during adipose development, (3) the mechanical regulators involved in adipose growth, and (4) the proteolytic and paracrine oversight for matrix remodeling during adipose development. It is crucial to gain a better understanding of the complex relationships that exist between adipose tissue and the vasculature during tissue development to provide insights into the pathological tissue expansion of obesity and to develop improved soft-tissue reconstruction techniques.

GDF11 inhibits adipogenesis and improves mature adipocytes metabolic function via WNT/β-catenin and ALK5/SMAD2/3 pathways

Objective

GDF11 is a member of the TGF‐β superfamily that was recently implicated as potential “rejuvenating” factor, which can ameliorate metabolic disorders. The main objective of the presented study was to closely characterize the role of GDF11 signaling in the glucose homeostasis and in the differentiation of white adipose tissue.

Methods

We performed microscopy imaging, biochemical and transcriptomic analyses of adipose tissues of 9 weeks old ob/ob mice and murine and human pre‐adipocyte cell lines.

Results

Our in vivo experiments employing GDF11 treatment in ob/ob mice showed improved glucose/insulin homeostasis, decreased weight gain and white adipocyte size. Furthermore, GDF11 treatment inhibited adipogenesis in pre‐adipocytes by ALK5‐SMAD2/3 activation in cooperation with the WNT/β‐catenin pathway, whose inhibition resulted in adipogenic differentiation. Lastly, we observed significantly elevated levels of the adipokine hormone adiponectin and increased glucose uptake by mature adipocytes upon GDF11 exposure.

Conclusion

We show evidence that link GDF11 to adipogenic differentiation, glucose, and insulin homeostasis, which are pointing towards potential beneficial effects of GDF11‐based “anti‐obesity” therapy.

The Association of Acute Phase Proteins in Stress and Inflammation-Induced T2D

Acute phase proteins (APPs), such as plasminogen activator inhibitor-1 (PAI-1), serum amyloid A (SAA), and C-reactive protein (CRP), are elevated in type-2 diabetes (T2D) and are routinely used as biomarkers for this disease. These APPs are regulated by the peripheral mediators of stress (i.e., endogenous glucocorticoids (GCs)) and inflammation (i.e., pro-inflammatory cytokines), with both implicated in the development of insulin resistance, the main risk factor for the development of T2D. In this review we propose that APPs, PAI-1, SAA, and CRP, could be the causative rather than only a correlative link between the physiological elements of risk (stress and inflammation) and the development of insulin resistance.

The Roles and Associated Mechanisms of Adipokines in Development of Metabolic Syndrome

Metabolic syndrome is a cluster of metabolic indicators that increase the risk of diabetes and cardiovascular diseases. Visceral obesity and factors derived from altered adipose tissue, adipokines, play critical roles in the development of metabolic syndrome. Although the adipokines leptin and adiponectin improve insulin sensitivity, others contribute to the development of glucose intolerance, including visfatin, fetuin-A, resistin, and plasminogen activator inhibitor-1 (PAI-1). Leptin and adiponectin increase fatty acid oxidation, prevent foam cell formation, and improve lipid metabolism, while visfatin, fetuin-A, PAI-1, and resistin have pro-atherogenic properties. In this review, we briefly summarize the role of various adipokines in the development of metabolic syndrome, focusing on glucose homeostasis and lipid metabolism.

Associations Among Adipose Tissue Immunology, Inflammation, Exosomes and Insulin Sensitivity in People With Obesity and Nonalcoholic Fatty Liver Disease

BACKGROUND AND AIMS

Insulin resistance is a key factor in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). We evaluated the importance of subcutaneous abdominal adipose tissue (SAAT) inflammation and both plasma and SAAT-derived exosomes in regulating insulin sensitivity in people with obesity and NAFLD.

METHODS

Adipose tissue inflammation (macrophage and T-cell content and expression of proinflammatory cytokines), liver and whole-body insulin sensitivity (assessed using a hyperinsulinemic-euglycemic clamp and glucose tracer infusion), and 24-hour serial plasma cytokine concentrations were evaluated in 3 groups stratified by adiposity and intrahepatic triglyceride (IHTG) content: (1) lean with normal IHTG content (LEAN; N = 14); (2) obese with normal IHTG content (OB-NL; N = 28); and (3) obese with NAFLD (OB-NAFLD; N = 28). The effect of plasma and SAAT-derived exosomes on insulin-stimulated Akt phosphorylation in human skeletal muscle myotubes and mouse primary hepatocytes was assessed in a subset of participants.

RESULTS

Proinflammatory macrophages, proinflammatory CD4 and CD8 T-cell populations, and gene expression of several cytokines in SAAT were greater in the OB-NAFLD than the OB-NL and LEAN groups. However, with the exception of PAI-1, which was greater in the OB-NAFLD than the LEAN and OB-NL groups, 24-hour plasma cytokine concentration areas-under-the-curve were not different between groups. The percentage of proinflammatory macrophages and plasma PAI-1 concentration areas-under-the-curve were inversely correlated with both hepatic and whole-body insulin sensitivity. Compared with exosomes from OB-NL participants, plasma and SAAT-derived exosomes from the OB-NAFLD group decreased insulin signaling in myotubes and hepatocytes.

CONCLUSIONS

Systemic insulin resistance in people with obesity and NAFLD is associated with increased plasma PAI-1 concentrations and both plasma and SAAT-derived exosomes. ClinicalTrials.gov number: NCT02706262 (https://clinicaltrials.gov/ct2/show/NCT02706262).

Adipose-PAS interactions in the context of its localised bio-engineering potential (Review)

Adipocytes are a known source of stem cells. They are easy to harvest, and are a suitable candidate for autogenous grafts. Adipose derived stem cells (ADSCs) have multiple target tissues which they can differentiate into, including bone and cartilage. In adipose tissue, ADSCs are able to differentiate, as well as providing energy and a supply of cytokines/hormones to manage the hypoxic and lipid/hormone saturated adipose environment. The plasminogen activation system (PAS) controls the majority of proteolytic activities in both adipose and wound healing environments, allowing for rapid cellular migration and tissue remodelling. While the primary activation pathway for PAS occurs through the urokinase plasminogen activator (uPA), which is highly expressed by endothelial cells, its function is not limited to enabling revascularisation. Proteolytic activity is dependent on protease activation, localisation, recycling mechanisms and substrate availability. uPA and uPA activated plasminogen allows pluripotent cells to arrive to new local environments and fulfil the niche demands. However, overstimulation, the acquisition of a migratory phenotype and constant protein turnover can be unconducive to the formation of structured hard and soft tissues. To maintain a suitable healing pattern, the proteolytic activity stimulated by uPA is modulated by plasminogen activator inhibitor 1. Depending on the physiological settings, different parts of the remodelling mechanism are activated with varying results. Utilising the differences within each microenvironment to recreate a desired niche is a valid therapeutic bio-engineering approach. By controlling the rate of protein turnover combined with a receptive stem cell lineage, such as ADSC, a novel avenue on the therapeutic opportunities may be identified, which can overcome limitations, such as scarcity of stem cells, low angiogenic potential or poor host tissue adaptation.

TMT-based quantitative proteomics analysis reveals the key proteins related with the differentiation process of goat intramuscular adipocytes

Background

Intramuscular adipocytes differentiation is a complex process, which is regulated by various transcription factor, protein factor regulators and signal transduction pathways. However, the proteins and signal pathways that regulates goat intramuscular adipocytes differentiation remains unclear.

Result

In this study, based on nanoscale liquid chromatography mass spectrometry analysis (LC-MS/MS), the tandem mass tag (TMT) labeling analysis was used to investigate the differentially abundant proteins (DAPs) related with the differentiation process of goat intramuscular adipocytes. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes enrichment and protein-protein interaction network analyses were performed for the characterization of the identified DAPs. The candidate proteins were verified by parallel reaction monitoring analysis. As a result, a total of 123 proteins, 70 upregulation proteins and 53 downregulation proteins, were identified as DAPs which may be related with the differentiation process of goat intramuscular adipocytes. Furthermore, the cholesterol metabolism pathway, glucagon signaling pathway and glycolysis / gluconeogenesis pathway were noticed that may be the important signal pathways for goat Intramuscular adipocytes differentiation.

Conclusions

By proteomic comparison between goat intramuscular preadipocytes (P_IMA) and intramuscular adipocytes (IMA), we identified a series protein that might play important role in the goat intramuscular fat differentiation, such as SRSF10, CSRP3, APOH, PPP3R1, CRTC2, FOS, SERPINE1 and AIF1L, could serve as candidates for further elucidate the molecular mechanism of IMF differentiation in goats.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07730-y.

Association of Adipose Tissue and Adipokines with Development of Obesity-Induced Liver Cancer

Obesity is rapidly dispersing all around the world and is closely associated with a high risk of metabolic diseases such as insulin resistance, dyslipidemia, and nonalcoholic fatty liver disease (NAFLD), leading to carcinogenesis, especially hepatocellular carcinoma (HCC). It results from an imbalance between food intake and energy expenditure, leading to an excessive accumulation of adipose tissue (AT). Adipocytes play a substantial role in the tumor microenvironment through the secretion of several adipokines, affecting cancer progression, metastasis, and chemoresistance via diverse signaling pathways. AT is considered an endocrine organ owing to its ability to secrete adipokines, such as leptin, adiponectin, resistin, and a plethora of inflammatory cytokines, which modulate insulin sensitivity and trigger chronic low-grade inflammation in different organs. Even though the precise mechanisms are still unfolding, it is now established that the dysregulated secretion of adipokines by AT contributes to the development of obesity-related metabolic disorders. This review focuses on several obesity-associated adipokines and their impact on obesity-related metabolic diseases, subsequent metabolic complications, and progression to HCC, as well as their role as potential therapeutic targets. The field is rapidly developing, and further research is still required to fully understand the underlying mechanisms for the metabolic actions of adipokines and their role in obesity-associated HCC.

Decreased adipose tissue oxygenation associates with insulin resistance in individuals with obesity

BACKGROUNDData from studies conducted in rodent models have shown that decreased adipose tissue (AT) oxygenation is involved in the pathogenesis of obesity-induced insulin resistance. Here, we evaluated the potential influence of AT oxygenation on AT biology and insulin sensitivity in people.METHODSWe evaluated subcutaneous AT oxygen partial pressure (pO2); liver and whole-body insulin sensitivity; AT expression of genes and pathways involved in inflammation, fibrosis, and branched-chain amino acid (BCAA) catabolism; systemic markers of inflammation; and plasma BCAA concentrations, in 3 groups of participants that were rigorously stratified by adiposity and insulin sensitivity: metabolically healthy lean (MHL; n = 11), metabolically healthy obese (MHO; n = 15), and metabolically unhealthy obese (MUO; n = 20).RESULTSAT pO2 progressively declined from the MHL to the MHO to the MUO group, and was positively associated with hepatic and whole-body insulin sensitivity. AT pO2 was positively associated with the expression of genes involved in BCAA catabolism, in conjunction with an inverse relationship between AT pO2 and plasma BCAA concentrations. AT pO2 was negatively associated with AT gene expression of markers of inflammation and fibrosis. Plasma PAI-1 increased from the MHL to the MHO to the MUO group and was negatively correlated with AT pO2, whereas the plasma concentrations of other cytokines and chemokines were not different among the MHL and MUO groups.CONCLUSIONThese results support the notion that reduced AT oxygenation in individuals with obesity contributes to insulin resistance by increasing plasma PAI-1 concentrations and decreasing AT BCAA catabolism and thereby increasing plasma BCAA concentrations.TRIAL REGISTRATIONClinicalTrials.gov NCT02706262.FUNDINGThis study was supported by NIH grants K01DK109119, T32HL130357, K01DK116917, R01ES027595, P42ES010337, DK56341 (Nutrition Obesity Research Center), DK20579 (Diabetes Research Center), DK052574 (Digestive Disease Research Center), and UL1TR002345 (Clinical and Translational Science Award); NIH Shared Instrumentation Grants S10RR0227552, S10OD020025, and S10OD026929; and the Foundation for Barnes-Jewish Hospital.

Development of a Biodegradable Microcarrier for the Cultivation of Human Adipose Stem Cells (hASCs) with a Defined Xeno- and Serum-Free Medium

Stirred single-use bioreactors in combination with microcarriers (MCs) have established themselves as a technology that has the potential to meet the demands of current and future cell therapeutic markets. However, most of the published processes have been performed using fetal bovine serum (FBS) containing cell culture medium and non-biocompatible MCs. This approach has two significant drawbacks: firstly, the inevitable potential risks associated with the use of FBS for clinical applications; secondly, non-biocompatible MCs have to be removed from the cell suspension before implantation, requiring a step that causes loss of viable cells and adds further costs and complications. This study aimed to develop a new platform based on a chemically defined xeno- and serum-free cell culture medium and biodegradable MC that can support the growth of human adipose stem cells (hASCs) while still preserving their undifferentiated status. A specific combination of components and manufacturing parameters resulted in a MC prototype, called “BR44”, which delivered the desired functionality. MC BR44 allows the hASCs to stick to its surface and grow in a chemically defined xeno- and serum-free medium (UrSuppe). Although the cells’ expansion rate was not as high as with a commercial non-biodegradable standard MC, those cultured on BR44 maintained a better undifferentiated status in both static and dynamic conditions than those cultured on traditional 2D surfaces.

Elastin-derived peptide VGVAPG decreases differentiation of mouse embryo fibroblast (3T3-L1) cells into adipocytes

Elastin is a highly elastic protein present in connective tissue. As a result of protease activity, elastin hydrolysis occurs, and during this process, elastin-derived peptides (EDPs) are released. One of the constitutively repeating elastin and EDP building sequences is the hexapeptide VGVAPG. Therefore, the aim of our research was to define the effect of VGVAPG peptide on adipogenesis in a mouse 3T3-L1 cell line. 3T3-L1 cells were differentiated according to a previously described protocol and exposed to increasing concentrations of VGVAPG or VVGPGA peptide. The obtained results showed that VGVAPG peptide does not stimulate reactive oxygen species (ROS) production, caspase-1 activation, and 3T3-L1 cell proliferation. In the second part of the experiments, it was proved that VGVAPG peptide decreased lipid accumulation as measured by oil red O staining, which was confirmed by the profile of increased expression markers of undifferentiated preadipocytes. In our experiments, 10 nM VGVAPG added for differentiating to adipocytes increased the expression of Pref-1, serpin E1, and adiponectin as compared to rosiglitazone (PPARγ agonist)-treated group and simultaneously decreased the expression of VEGF and resistin as compared to the rosiglitazone-treated group. The obtained results show that VGVAPG peptide sustains 3T3 cells in undifferentiated state.

ABBREVIATIONS

DMSO: dimethyl sulphoxide; EBP: elastin-binding protein; EDPs: elastin-derived peptides; FBS: foetal bovine serum; Glb1: gene for beta-galactosidase; LDL: low-density-lipoprotein; PAI-1 (Serpin E1): plasminogen activator inhibitor-1; PBS: phosphate-buffered saline; PPARγ: peroxisome proliferator-activated receptor gamma; Pref-1: preadipocyte factor 1; ROS: reactive oxygen species; VEGF-A: vascular endothelial growth factor-A; VGVAPG: Val-Gly-Val-Ala-Pro-Gly; β-Gal: beta-galactosidase; ORO: oil red O; IBMX: 3-isobutyl-1-methylxanthine; H2DCFDA: 2',7'-dichlorodihydrofluorescein diacetate; DMEM: Dulbecco's Modified Eagle's Medium; VVGPGA: Val-Val-Gly-Pro-Gly-Ala.

Autophagy inhibition in 3T3-L1 adipocytes breaks the crosstalk with tumor cells by suppression of adipokine production

Several studies have revealed the functional importance of autophagy in both adipogenesis and carcinogenesis. Here, we investigated autophagy as a link between tumorigenesis and adipogenesis using 3T3-L1 cells, which have been shown to closely mimic the in vivo differentiation process. The relative levels of LC3-II/I showed that autophagy was the highest after 4–6 days of initiation of differentiation and it diminished thereafter. Furthermore, chloroquine (CQ), a late autophagy inhibitor, effectively inhibited adipogenic differentiation of 3T3-L1 cells, suggesting that autophagy may have a positive impact on adipogenic differentiation. Notably, real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis showed that CQ completely blocked the mRNA expression of three adipokines (adiponectin, leptin, and peroxisome proliferator-activated receptor-γ (PPARγ)), which increased proportionally to adipocyte differentiation. Using adipokine antibody arrays, we also found that among 38 adipokines examined, 6 adipokines were significantly differentially regulated in mature adipocytes compared to those in preadipocytes. A comparative analysis of adipokine production revealed that CQ-treated adipocytes displayed a profile similar to that of preadipocytes. Subsequently, CQ treatment significantly inhibited the migration capacity of v-Ha-ras-transformed cells in both 3T3-L1 adipocyte-conditioned medium and co-culture with 3T3-L1 using a transwell plate. Taken together, our results suggest that autophagy inhibition blocks the production of mediators relevant to the adipogenic process and may significantly contribute to reducing obesity-related cancer risk.

Adipogenic function of mouse tetranectin and identification of its functional domain

Tetranectin (TN), a plasminogen (Plg) binding protein, enhances the Plg activator (PA)-catalyzed activation of Plg to plasmin (Pln). Previously, TN was identified as an adipogenic serum protein, which promotes adipocyte differentiation. In the present study, we investigated the adipogenic function of mouse TN using recombinant proteins (rmTNs) in full-length and domain-truncated forms. Adipocyte differentiation in TN-depleted-FBS-media was significantly enhanced by rmTNs supplementation. The adipogenic effect of rmTNs was found to be dependent on the presence of a Plg binding domain, indicating the domain is essential for the adipogenic function of mTN. In addition, these results suggested the involvement of Plg activation, however Plg, PA and Pln appeared to have no direct effect on adipocyte differentiation. This study demonstrates the adipogenic function of mTN, which is dependent on the Plg binding domain as its functional domain.

Influence of skeletal muscle mass and fat mass on the metabolic and inflammatory profile in sarcopenic and non-sarcopenic overfat elderly

BACKGROUND

Sarcopenic elderly present low muscle mass and strength, however, it is not clear if the inflammatory and metabolic profile is more related to low lean mass or high fat mass in sarcopenic and non-sarcopenic overfat elderly.

AIM

To verify the difference in inflammatory and metabolic responses in sarcopenic and non-sarcopenic overfat elderly and the relationship between these markers, body composition, and strength in this population.

METHODS

Fifty-seven elderly were divided into two groups: sarcopenic (n = 30) and non-sarcopenic (n = 27). Body composition was evaluated with octopolar bioimpedance. Total cholesterol, high-density lipoprotein cholesterol, triacylglycerol, glucose, cortisol, leptin, adiponectin, Plasminogen activator inhibitor-1 (PAI-1), TNF-α, IL-6, IL-8, and IL-10 were assessed. The handgrip test was used to evaluate strength.

RESULTS

When comparing the inflammatory profile, sarcopenic individuals showed greater adiponectin concentration (p = 0.019), adiponectin/fat mass ratio (p < 0.001), adiponectin/visceral fat (p < 0.001), and higher PAI-1 (p = 0.019) than non-sarcopenic overfat elderly. After adjusting the inflammatory profile by skeletal muscle mass the significant differences between groups were maintained (p < 0.05) but no significant differences between groups were observed when adjusting by fat mass, despite a tendency to a significant difference for adiponectin concentration (p = 0.06). In addition, after adjusting leptin by fat mass there was a statistically significant lower concentration in the sarcopenic compared to non-sarcopenic overfat elderly.

CONCLUSION

Non-sarcopenic overfat elderly presented lower anti-inflammatory and anti-atherogenic responses than sarcopenic elderly. Furthermore, fat mass but not skeletal muscle mass seem to change these responses.

Inhibition of PAI-1 attenuates perirenal fat inflammation and the associated nephropathy in high-fat diet-induced obese mice

Plasminogen activator inhibitor-1 (PAI-1) is increasingly recognized as a mediator in extracellular matrix (ECM) accumulation in diabetic nephropathy. Previous studies have implicated PAI-1 in adipose tissue (AT) expansion, while also contributing to insulin resistance. As inflammation is also known to occur in perirenal AT during obesity, we hypothesized that in a high-fat diet (HFD)-induced obese mouse model, PAI-1 contributes to macrophage-mediated inflammation and diabetic nephropathy. The HFD mice showed increased expression of PAI-1 in perirenal fat and also displayed increased fat weight and macrophage numbers. We found that the macrophage polarization, proinflammatory macrophage-M1-phenotype, including CD11c, IL-6, and monocyte chemoattractant protein-1, were increased by an HFD and decreased by either the genetic depletion of PAI-1 or treatment with the PAI-1 inhibitor, PAI-039. Similarly, an enhanced anti-inflammatory M2-phenotype, including CD206 and IL-10, was accompanied by either the genetic deletion of PAI-1 or PAI-039 treatment. Furthermore, the inhibition of PAI-1 reduced HFD-induced renal histological lesions and abated profibrotic/extracellular-matrix protein. Collectively, our findings provide support that PAI-1 contributes to the development of inflammation in perirenal fat and correlates with the development of diabetic nephropathy in HFD-induced obesity.

Decrease in αβ/γδ T-cell ratio is accompanied by a reduction in high-fat diet-induced weight gain, insulin resistance, and inflammation

The implication of αβ and γδ T cells in obesity-associated inflammation and insulin resistance (IR) remains uncertain. Mice lacking γδ T cells show either no difference or a decrease in high-fat diet (HFD)-induced IR, whereas partial depletion in γδ T cells does not protect from HFD-induced IR. αβ T-cell deficiency leads to a decrease in white adipose tissue (WAT) inflammation and IR without weight change, but partial depletion of these cells has not been studied. We previously described a mouse model overexpressing peroxisome proliferator-activated receptor β (PPAR-β) specifically in T cells [transgenic (Tg) T-PPAR-β] that exhibits a partial depletion in αβ T cells and no change in γδ T-cell number. This results in a decreased αβ/γδ T-cell ratio in lymphoid organs. We now show that Tg T-PPAR-β mice are partially protected against HFD-induced weight gain and exhibit decreased IR and liver steatosis independently of animal weight. These mice display an alteration of WAT-depots distribution with an increased epididymal-WAT mass and a decreased subcutaneous WAT mass. Immune cell number is decreased in both WAT-depots, except for γδ T cells, which are increased in epididymal-WAT. Overall, we show that decreasing αβ/γδ T-cell ratio in WAT-depots alters their inflammatory state and mass repartition, which might be involved in improvement of insulin sensitivity.-Le Menn, G., Sibille, B., Murdaca, J., Rousseau, A.-S., Squillace, R., Vergoni, B., Cormont, M., Niot, I., Grimaldi, P. A., Mothe-Satney, I., Neels, J. G. Decrease in αβ/γδ T-cell ratio is accompanied by a reduction in high-fat diet-induced weight gain, insulin resistance, and inflammation.

Drugs Involved in Dyslipidemia and Obesity Treatment: Focus on Adipose Tissue

Metabolic syndrome can be defined as a state of disturbed metabolic homeostasis characterized by visceral obesity, atherogenic dyslipidemia, arterial hypertension, and insulin resistance. The growing prevalence of metabolic syndrome will certainly contribute to the burden of cardiovascular disease. Obesity and dyslipidemia are main features of metabolic syndrome, and both can present with adipose tissue dysfunction, involved in the pathogenic mechanisms underlying this syndrome. We revised the effects, and underlying mechanisms, of the current approved drugs for dyslipidemia and obesity (fibrates, statins, niacin, resins, ezetimibe, and orlistat; sibutramine; and diethylpropion, phentermine/topiramate, bupropion and naltrexone, and liraglutide) on adipose tissue. Specifically, we explored how these drugs can modulate the complex pathways involved in metabolism, inflammation, atherogenesis, insulin sensitivity, and adipogenesis. The clinical outcomes of adipose tissue modulation by these drugs, as well as differences of major importance for clinical practice between drugs of the same class, were identified. Whether solutions to these issues will be found in further adjustments and combinations between drugs already in use or necessarily in new advances in pharmacology is not known. To better understand the effect of drugs used in dyslipidemia and obesity on adipose tissue not only is challenging for physicians but could also be the next step to tackle cardiovascular disease.

Anti-adipogenic effects of the traditional herbal formula Dohongsamul-tang in 3T3-L1 adipocytes

Background

Blood stasis syndrome (BSS) is a general pattern identification and refers to pathological stagnation of blood circulation, dysfunction of endothelial cells or metabolic disorder in traditional Korean medicine (TKM). Dohongsamul-Tang (DHSMT) is a well-known traditional herbal formula which used for treatment and prevention of BSS by promoting blood circulation in TKM.

Methods

Cytotoxicity of DHSMT was examined by cell counting kit-8 (CCK-8). We also investigated the anti-adipogenesis effect of DHSMT by using Oil Red O staining, intracellular triglyceride assay leptin ELISA and western blot analysis in 3T3-L1 adipocytes. In addition, the accumulation of adiponectin, resistin and plasminogen activator inhibitor-1 (PAI-1) were measured by magnetic bead panel kit.

Results

Oil Red O staining showed that DHSMT markedly reduced fat accumulation without affecting cell cytotoxicity. DHSMT also significantly decreased accumulation of triglyceride and adipokines such as leptin, adiponectin, resistin and PAI-1 compared with fully differentiated adipocytes. Furthermore, our results found that DHSMT significantly suppressed the adipocyte differentiation by downregulating adipogenic-specific transcriptional factors such as peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer binding proteins alpha (C/EBPα) and fatty acid binding protein 4 (FABP4) in adipocytes.

Conclusions

Taken together, our findings provide that DHSMT has potential for treatment and prevention of obesity or MS related to BSS.

Thrombosis in central obesity and metabolic syndrome: Mechanisms and epidemiology

Central obesity is a key feature of the metabolic syndrome (metS), a multiplex risk factor for subsequent development of type 2 diabetes and cardiovascular disease. Many metabolic alterations closely related to this condition exert effects on platelets and vascular cells. A procoagulant and hypofibrinolytic state has been identified, mainly underlain by inflammation, oxidative stress, dyslipidaemia, and ectopic fat that accompany central obesity. In support of these data, central obesity independently predisposes not only to atherothrombosis but also to venous thrombosis.

Association of vitronectin and plasminogen activator inhibitor-1 levels with the risk of metabolic syndrome and type 2 diabetes mellitus

It was the objective of this study to investigate the relation between vitronectin and plasminogen activator inhibitor (PAI)-1 plasma levels with nine-year incidences of the metabolic syndrome (MetS) and of type 2 diabetes mellitus (T2DM). Baseline plasma concentrations of vitronectin and PAI-1 were measured in 627 healthy participants from the prospective D.E.S.I.R. cohort who subsequently developed MetS (n=487) and T2DM (n=182) over a nine-year follow-up (42 presented both) and who were matched with two healthy control subjects each by use of a nested case-control design. Parameters composing the MetS explained about 20% of plasma vitronectin levels. An increase of one standard deviation of vitronectin was associated with increased risks of both the MetS (odds ratio [OR] = 1.21 [1.07 – 1.37], p = 0.003) and T2DM (OR = 1.24 [1.01 – 1.53], p = 0.045). Corresponding ORs for PAI-1 levels were 1.46 [1.27 – 1.68] (p < 10−4) and 1.40 [1.14 – 1.72] (p = 0.0012). However, the effects of vitronectin and PAI-1 levels on outcomes were not independent. The vitronectin–MetS association was restricted to individuals with low to modest PAI-1 levels (OR = 1.33 [1.14 – 1.54], p = 0.0003) while no association was observed in individuals with high PAI-1 levels (OR = 0.87 [0.68 – 1.10], p = 0.24), the test for interaction being highly significant (p = 0.0009). In conclusion, baseline plasma vitronectin is a marker of incident MetS at nine years. Its predictive ability for MetS and T2DM should not be assessed independently of PAI-1 levels.

Global transcriptome analysis identifies differentially expressed genes related to lipid metabolism in Wagyu and Holstein cattle

Fat deposition of beef cattle varies between breeds. However, the regulation mechanism is still not elucidated completely at molecular level. In the present study, we comparatively analyzed transcriptome of subcutaneous adipose tissue between Wagyu and Holstein cattle with a significant difference in fat deposition to identify key genes associated with fat metabolism and adipogenesis by high-throughput RNA-seq technology. A total of 59,149,852 and 69,947,982 high quality reads were generated, respectively. With further analysis, 662 differentially expressed genes were identified. Gene Ontology and KEGG pathway analysis revealed that many differentially expressed genes were enriched in several biological processes and pathways relevant to adipogenesis and lipid metabolism, in which PPAR and fatty acid metabolism signaling pathways with related genes such as PPARγ, PLIN2 and ELOVL6 et al. play a critical role. Protein-protein interaction network analysis showed EGR1, FOS, SERPINE1, AGT, MMP2 may have great impact on adipocyte differentiation and adipogenesis. Moreover, potential alternative splicing events and single nucleotide polymorphisms (SNPs) were also identified. In summary, we comprehensively analyzed and discussed the transcriptome of subcutaneous adipose tissue of Wagyu and Holstein cattle, which might provide a theoretical basis for better understanding molecular mechanism of fat metabolism and deposition in beef cattle.

Cardiovascular-renal complications and the possible role of plasminogen activator inhibitor: a review

Since angiotensin increases the expression of plasminogen activator inhibitor (PAI), mechanisms associated with an actively functioning renin–angiotensin–aldosterone system can be expected to be associated with increased PAI-1 expression. These mechanisms are present not only in common conditions resulting in glomerulosclerosis associated with aging, diabetes or genetic mutations, but also in autoimmune disease (like scleroderma and lupus), radiation injury, cyclosporine toxicity, allograft nephropathy and ureteral obstruction. While the renin–angiotensin–aldosterone system and growth factors, such as transforming growth factor-beta (TGF-β), are almost always part of the process, there are rare experimental observations of PAI-1 expression without their interaction. Here we review the literature on PAI-1 and its role in vascular, fibrotic and oxidative injury as well as work suggesting potential areas of intervention in the pathogenesis of multiple disorders.

Decreased Insulin Sensitivity and Impaired Fibrinolytic Activity in Type 2 Diabetes Patients and Nondiabetics with Ischemic Stroke

We analyzed (a) insulin sensitivity (IS), (b) plasma insulin (PI), and (c) plasminogen activator inhibitor-1 (PAI-1) in type 2 diabetes (T2D) patients with (group A) and without (group B) atherothrombotic ischemic stroke (ATIS), nondiabetics with ATIS (group C), and healthy controls (group D). IS was determined by minimal model (Si). Si was lower in A versus B (1.18 ± 0.67 versus 2.82 ± 0.61 min-1/mU/L × 104; P < 0.001) and in C versus D (3.18 ± 0.93 versus 6.13 ± 1.69 min-1/mU/L × 104; P < 0.001). PI and PAI-1 were higher in A versus B (PI: 19.61 ± 4.08 versus 14.91 ± 1.66 mU/L; P < 0.001, PAI-1: 7.75 ± 1.04 versus 4.57 ± 0.72 mU/L; P < 0.001) and in C versus D (PI: 15.14 ± 2.20 versus 7.58 ± 2.05 mU/L; P < 0.001, PAI-1: 4.78 ± 0.98 versus 3.49 ± 1.04 mU/L; P < 0.001). Si correlated with PAI-1 in T2D patients and nondiabetics, albeit stronger in T2D. Binary logistic regression identified insulin, PAI-1, and Si as independent predictors for ATIS in T2D patients and nondiabetics. The results imply that insulin resistance and fasting hyperinsulinemia might exert their atherogenic impact through the impaired fibrinolysis.

Metabolic syndrome in pediatrics

The ever growing prevalence of childhood obesity is being accompanied by an increase in the pediatric population of diseases once believed to be exclusive of the adulthood such as the metabolic syndrome (MS). The MS has been defined as the link between insulin resistance, hypertension, dyslipidemia, impaired glucose tolerance, and other metabolic abnormalities associated with an increased risk of atherosclerotic cardiovascular diseases in adults. In this review, we will discuss the peculiar aspects of the pediatric MS and the role of novel molecules and biomarkers in its pathogenesis.

Adipocyte transdifferentiation and its molecular targets

According to the World Health Organization obesity is defined as the excessive accumulation of fat, which increases risk of other metabolic disorders such as insulin resistance, dyslipidemia, hypertension, cardiovascular diseases, etc. There are two types of adipose tissue, white and brown adipose tissue (BAT) and the latter has recently gathered interest of the scientific community. Discovery of BAT has opened avenues for a new therapeutic strategy for the treatment of obesity and related metabolic syndrome. BAT utilizes accumulated fatty acids for energy expenditure; hence it is seen as one of the possible alternates to the current treatment. Moreover, browning of white adipocyte on exposure to cold, as well as with some of the pharmacological agents presents exciting outcomes and indicates the feasibility of transdifferentiation. A better understanding of molecular pathways and differentiation factors, those that play a key role in transdifferentiation are of extreme importance in designing novel strategies for the treatment of obesity and associated metabolic disorders.

Novel role of nuclear receptor Rev-erbα in hepatic stellate cell activation: potential therapeutic target for liver injury

Hepatic stellate cell (HSC) transdifferentiation from a quiescent, adipocyte-like cell to a highly secretory and contractile myofibroblast-like phenotype contributes to negative pathological consequences, including fibrosis/cirrhosis with portal hypertension (PH). Antiadipogenic mechanisms have been shown to underlie activation of HSCs. We examined the role of heme-sensing nuclear receptor Rev-erbα, a transcriptional repressor involved in metabolic and circadian regulation known to promote adipogenesis in preadipocytes, in HSC transdifferentiation. We discovered that Rev-erbα protein was up-regulated in activated HSCs and injured livers; however, transcriptional repressor activity was not affected by fibrogenic treatments. Surprisingly, increased protein expression was accompanied with increased cytoplasmic accumulation of Rev-erbα, which demonstrated distributions similar to myosin, the major cellular motor protein. Cells overexpressing a cytoplasm-localized Rev-erbα exhibited enhanced contractility. Ectopically expressed Rev-erbα responded to both adipogenic ligand and fibrogenic transforming growth factor beta treatment. Rev-erb ligand SR6452 down-regulated cytoplasmic expression of Rev-erbα, decreased expression of fibrogenic markers and the activated phenotype in HSCs, and ameliorated fibrosis and PH in rodent models.

CONCLUSIONS

Up-regulation of Rev-erbα is an intrinsic fibrogenic response characterized by cytoplasmic accumulation of the protein in activated HSCs. Cytoplasmic expression of Rev-erbα promotes a contractile phenotype. Rev-erbα acts as a bifunctional regulator promoting either anti- or profibrogenic response, depending on milieu. Rev-erb ligand SR6452 functions by a previously undescribed mechanism, targeting both nuclear activity and cytoplasmic expression of Rev-erbα. Our studies identify Rev-erbα as a novel regulator of HSC transdifferentiation and offers exciting new insights on the therapeutic potential of Rev-erb ligands.

Obesity and its metabolic complications: the role of adipokines and the relationship between obesity, inflammation, insulin resistance, dyslipidemia and nonalcoholic fatty liver disease

Accumulating evidence indicates that obesity is closely associated with an increased risk of metabolic diseases such as insulin resistance, type 2 diabetes, dyslipidemia and nonalcoholic fatty liver disease. Obesity results from an imbalance between food intake and energy expenditure, which leads to an excessive accumulation of adipose tissue. Adipose tissue is now recognized not only as a main site of storage of excess energy derived from food intake but also as an endocrine organ. The expansion of adipose tissue produces a number of bioactive substances, known as adipocytokines or adipokines, which trigger chronic low-grade inflammation and interact with a range of processes in many different organs. Although the precise mechanisms are still unclear, dysregulated production or secretion of these adipokines caused by excess adipose tissue and adipose tissue dysfunction can contribute to the development of obesity-related metabolic diseases. In this review, we focus on the role of several adipokines associated with obesity and the potential impact on obesity-related metabolic diseases. Multiple lines evidence provides valuable insights into the roles of adipokines in the development of obesity and its metabolic complications. Further research is still required to fully understand the mechanisms underlying the metabolic actions of a few newly identified adipokines.

Effect of a 12-month exercise intervention on serum biomarkers of angiogenesis in postmenopausal women: a randomized controlled trial

BACKGROUND

Increased physical activity is associated with decreased risk of several types of cancer, but underlying mechanisms are poorly understood. Angiogenesis, in which new blood vessels are formed, is common to adipose tissue formation/remodeling and tumor vascularization.

METHODS

We examined effects of a 12-month 45 minutes/day, 5 days/week moderate-intensity aerobic exercise intervention on four serum markers of angiogenesis in 173 sedentary, overweight, postmenopausal women, 50 to 75 years, randomized to intervention versus stretching control. Circulating levels of positive regulators of angiogenesis [VEGF, osteopontin (OPN), plasminogen activator inhibitor-1 (PAI-1)], and the negative regulator pigment epithelium-derived factor (PEDF), were measured by immunoassay at baseline and 12 months. Changes were compared using generalized estimating equations, adjusting for baseline levels of analytes and body mass index (BMI).

RESULTS

VEGF, OPN, or PAI-1 levels did not differ by intervention arm. Participants randomized to exercise significantly reduced PEDF (-3.7%) versus controls (+3.0%; P = 0.009). Reductions in fat mass were significantly associated with reductions in PAI-1 (Ptrend = 0.03; Ptrend = 0.02) and PEDF (Ptrend = 0.002; Ptrend = 0.01) compared with controls, or to those who gained any fat mass respectively. There was a significant association between decreases in VO2max, and increased reductions in PEDF (Ptrend = 0.03), compared with participants who increased their level of fitness.

CONCLUSIONS

Fat loss reduces circulating PAI-1 and PEDF. Changes in VO2max are associated with alterations in PEDF, but these associations are complex.

IMPACT

Unexpected reductions in PEDF with decreasing fat mass, and with decreasing VO2max, warrant further study, including examining the effects of different types and intensities of exercise; and role of dietary weight-loss with and without exercise.

Adiposopathy: how do diet, exercise and weight loss drug therapies improve metabolic disease in overweight patients?

An increase in bodyweight is generally associated with an increased risk of excessive fat-related metabolic diseases (EFRMD), including Type 2 diabetes mellitus, hypertension and dyslipidemia. However, not all patients who are overweight have EFRMD, and not all patients with EFRMD are significantly overweight. The adipocentric paradigm provides the basis for a unifying, pathophysiological process whereby fat gain in susceptible patients leads to fat dysfunction ('sick fat'), and wherein pathological abnormalities in fat function (adiposopathy) are more directly related to the onset of EFRMD than increases in fat mass (adiposity) alone. But just as worsening fat function worsens EFRMD, improved fat function improves EFRMD. Peroxisome proliferator-activated receptor-gamma agonists increase the recruitment, proliferation and differentiation of preadipocytes ('healthy fat') and cause apoptosis of hypertrophic and dysfunctional (including visceral) adipocytes resulting in improved fat function and improved metabolic parameters associated with EFRMD. Weight loss interventions, such as a hypocaloric diet and physical exercise, in addition to agents such as orlistat, sibutramine and cannabinoid receptor antagonists, may have favorable effects upon fat storage (lipogenesis and fat distribution), nutrient metabolism (such as free fatty acids), favorable effects upon adipose tissue factors involved in metabolic processes and inflammation, and enhanced 'cross-talk' with other major organ systems. In some cases, weight loss therapeutic agents may even affect metabolic parameters and adipocyte function independently of weight loss alone, suggesting that the benefit of these agents in improving EFRMD may go beyond their efficacy in weight reduction. This review describes how adiposopathy interventions may affect fat function, and thus improve EFRMD.

Liver fat content is linked to inflammatory changes in subcutaneous adipose tissue in type 2 diabetes patients

BACKGROUND

Patients with type 2 diabetes mellitus (T2DM) are typically overweight and have an increased liver fat content (LFAT). High LFAT may be explained by an increased efflux of free fatty acids from the adipose tissue, which is partly instigated by inflammatory changes. This would imply an association between inflammatory features of the adipose tissue and liver fat content.

OBJECTIVE

To analyse associations between inflammatory features of the adipose tissue and liver fat content.

DESIGN

A cross-sectional study.

PATIENTS

Twenty-seven obese patients with insulin-treated T2DM were studied.

MEASUREMENTS

LFAT content was measured by proton magnetic resonance spectroscopy. A subcutaneous (sc) fat biopsy was obtained to determine morphology and protein levels within adipose tissue. In addition to fat cell size, the percentage of macrophages and the presence of crown-like structures (CLSs) within sc fat were assessed by CD68-immunohistochemical staining.

RESULTS

Mean LFAT percentage was 11·1 ± 1·7% (range: 0·75-32·9%); 63% of the patients were diagnosed with an elevated LFAT (upper range of normal ≤5·5%). Whereas adipocyte size did not correlate with LFAT, 3 of 4 subjects with CLSs in sc fat had elevated LFAT and the percentage of macrophages present in sc adipose tissue was positively associated with LFAT. Protein concentrations of adiponectin within adipose tissue negatively correlated with LFAT. Adipose tissue protein levels of the key inflammatory adipokine plasminogen activator inhibitor-1 (PAI-1) were positively associated with LFAT.

CONCLUSIONS

Several pro-inflammatory changes in sc adipose tissue associate with increased LFAT content in obese insulin-treated patients with T2DM. These findings suggest that inflammatory changes at the level of the adipose tissue may drive liver fat accumulation.

Resistin affects lipid metabolism during adipocyte maturation of 3T3-L1 cells

Resistin, an adipose-tissue-specific secretory factor, aggravates metabolic syndrome through impairment of glucose metabolism. Previously, we demonstrated that resistin expression was induced in both 3T3-L1 cells and primary pre-adipocytes derived from Zucker obese rats during the process of differentiation and maturation (Ikeda Y, Hama S, Kajimoto K, Okuno T, Tsuchiya H & Kogure K (2011) Biol Pharm Bull 34, 865-870). However, the biological function of resistin in adipocytes is poorly understood. In the present study, we examined the effects of resistin knockdown on the biological features of 3T3-L1 cells. We found that lipid content was significantly decreased in 3T3-L1 cells transfected with anti-resistin small interfering RNA (siRNA) after adipocyte differentiation. While expression of peroxisome proliferator activated receptor γ and CCAAT/enhancer-binding protein α was not affected, protein expression and transcriptional activity levels of carbohydrate response element binding protein (ChREBP), which upregulates transcription of lipogenic genes, decreased after anti-resistin siRNA treatment. Moreover, gene expression of fatty acid synthase and acetyl-CoA carboxylase 2, which are known to be regulated by ChREBP, were also suppressed by resistin knockdown. In contrast, activity of the fatty acid β-oxidation-regulating protein carnitine palmitoyltransferase 1 increased. These results suggest that resistin knockdown induces suppression of lipid production and activation of fatty acid β-oxidation. Consequently, resistin may affect lipid metabolism during adipocyte maturation.

The inflammation highway: metabolism accelerates inflammatory traffic in obesity

As humans evolved, perhaps the two strongest selection determinants of survival were a robust immune response able to clear bacterial, viral, and parasitic infection and an ability to efficiently store nutrients to survive times when food sources were scarce. These traits are not mutually exclusive. It is now apparent that critical proteins necessary for regulating energy metabolism, such as peroxisome proliferator-activated receptors, Toll-like receptors, and fatty acid-binding proteins, also act as links between nutrient metabolism and inflammatory pathway activation in immune cells. Obesity in humans is a symptom of energy imbalance: the scale has been tipped such that energy intake exceeds energy output and may be a result, in part, of evolutionary selection toward a phenotype characterized by efficient energy storage. As discussed in this review, obesity is a state of low-grade, chronic inflammation that promotes the development of insulin resistance and diabetes. Ironically, the formation of systemic and/or local, tissue-specific insulin resistance upon inflammatory cell activation may actually be a protective mechanism that co-evolved to repartition energy sources within the body during times of stress during infection. However, the point has been reached where a once beneficial adaptive trait has become detrimental to the health of the individual and an immense public health and economic burden. This article reviews the complex relationship between obesity, insulin resistance/diabetes, and inflammation, and although the liver, brain, pancreas, muscle, and other tissues are relevant, we focus specifically on how the obese adipose microenvironment can promote immune cell influx and sustain damaging inflammation that can lead to the onset of insulin resistance and diabetes. Finally, we address how substrate metabolism may regulate the immune response and discuss how fuel uptake and metabolism may be a targetable approach to limit or abrogate obesity-induced inflammation.

Plasminogen activator inhibitor-1, free fatty acids, and insulin resistance in patients with myocardial infarction

BACKGROUND

Insulin resistance is known to be a common feature of type 2 diabetes mellitus and is regarded as an important mechanism in the pathogenesis of this disease. The key pathogenetic mechanisms of insulin resistance progression are free fatty acids metabolism impairment and enhanced activity of plasminogen activator inhibitor 1. Both free fatty acids and plasminogen activator inhibitor 1 are recognized as risk factors for coronary heart disease.

METHODS

THE PATIENTS WERE DIVIDED INTO TWO GROUPS: group 1 included 65 non-diabetic myocardial infarction patients and group 2 enrolled 60 diabetic myocardial infarction patients. The control group consisted of 30 sex- and age-matched volunteers. The concentration of serum free fatty acids, glucose, C-peptide, and insulin were measured on the 1st and 12th days of the study. All the patients had their postprandial glycemia, insulin, and C-peptide concentrations measured 2 hours after a standard carbohydrate breakfast containing 360 kcal (protein 20 g, carbohydrate 57 g, and fat 9 g).

RESULTS

Free fatty acids levels in group 1 and in group 2 exceeded the control group values by 7-fold and 11-fold, respectively. Plasminogen activator inhibitor 1 concentration was 2.5-fold higher in group 1 and 4.6-fold higher in group 2 compared to the control group on the 1st day from the myocardial infarction onset. In addition, plasminogen activator inhibitor 1 concentration was significantly reduced in both groups on the 12th day from the myocardial infarction onset; however, it did not achieve the control group values.

CONCLUSION

Increased postprandial glucose level, insulinemia, and elevated levels of free fatty acids and plasminogen activator inhibitor are associated with myocardial infarction-associated progression of insulin resistance. However, insulin resistance metabolic markers are of great predictive capacity in the assessment of risk of acute coronary events.

The plasminogen activation system modulates differently adipogenesis and myogenesis of embryonic stem cells

Regulation of the extracellular matrix (ECM) plays an important functional role either in physiological or pathological conditions. The plasminogen activation (PA) system, comprising the uPA and tPA proteases and their inhibitor PAI-1, is one of the main suppliers of extracellular proteolytic activity contributing to tissue remodeling. Although its function in development is well documented, its precise role in mouse embryonic stem cell (ESC) differentiation in vitro is unknown. We found that the PA system components are expressed at very low levels in undifferentiated ESCs and that upon differentiation uPA activity is detected mainly transiently, whereas tPA activity and PAI-1 protein are maximum in well differentiated cells. Adipocyte formation by ESCs is inhibited by amiloride treatment, a specific uPA inhibitor. Likewise, ESCs expressing ectopic PAI-1 under the control of an inducible expression system display reduced adipogenic capacities after induction of the gene. Furthermore, the adipogenic differentiation capacities of PAI-1(-/-) induced pluripotent stem cells (iPSCs) are augmented as compared to wt iPSCs. Our results demonstrate that the control of ESC adipogenesis by the PA system correspond to different successive steps from undifferentiated to well differentiated ESCs. Similarly, skeletal myogenesis is decreased by uPA inhibition or PAI-1 overexpression during the terminal step of differentiation. However, interfering with uPA during days 0 to 3 of the differentiation process augments ESC myotube formation. Neither neurogenesis, cardiomyogenesis, endothelial cell nor smooth muscle formation are affected by amiloride or PAI-1 induction. Our results show that the PA system is capable to specifically modulate adipogenesis and skeletal myogenesis of ESCs by successive different molecular mechanisms.

Obesity-related glomerulopathy and podocyte injury: a mini review

Obesity-related glomerulopathy (ORG) is morphologically defined as focal segmental glomerulosclerosis and glomerulomegaly. Podocyte hypertrophy and reduced density are related to proteinuria which in a portion of patients is in the nephrotic range and evolvs towards renal failure. This article reviews the pathogenetic mechanisms of podocyte injury or dysfunction and lists new possible antiproteinuric strategies based on pharmaceutical targeting of the reported pathogenetic mechanisms. The pathogenetic mechnisms discussed include: renin angiotensin system, plasminogen activation inhibitor-1 (PAI-1), lipid metabolism, adiponectin, macrophages and proinflammatory cytokines, oxidative stress. The proposed antiproteinuric strategies include: AT2 receptor blockers; adipokine complement C19 TNF-related protein-1 blocker; selective PAI-1 inhibitor; farnesoid x receptor activation; increase of circulating adiponectin; selective antiinflammatory drugs; more potent antioxidants (Heme oxigenase, NOX4 inhibitors). However, because ORG is a rare disease, the need for a long term pharmaceutical approach in obese proteinuric patients should be carefully evaluated and limited to the cases with progressive loss of renal function.