Adipokinome Signatures in Obese Mouse Models Reflect Adipose Tissue Health and Are Associated with Serum Lipid Composition

Adipocyte and hepatic lipid metabolism govern whole-body metabolic homeostasis, whereas a disbalance of de novo lipogenesis (DNL) in fat and liver might lead to obesity, with severe co-morbidities. Nevertheless, some obese people are metabolically healthy, but the “protective” mechanisms are not yet known in detail. Especially, the adipocyte-derived molecular mediators that indicate adipose functionality are poorly understood. We studied transgenic mice (alb-SREBP-1c) with a “healthy” obese phenotype, and obob mice with hyperphagia-induced “sick” obesity to analyze the impact of the tissue-specific DNL on the secreted proteins, i.e., the adipokinome, of the primary adipose cells by label-free proteomics. Compared to the control mice, adipose DNL is reduced in both obese mouse models. In contrast, the hepatic DNL is reduced in obob but elevated in alb-SREBP-1c mice. To investigate the relationship between lipid metabolism and adipokinomes, we formulated the “liver-to-adipose-tissue DNL” ratio. Knowledge-based analyses of these results revealed adipocyte functionality with proteins, which was involved in tissue remodeling or metabolism in the alb-SREBP-1c mice and in the control mice, but mainly in fibrosis in the obob mice. The adipokinome in “healthy” obesity is similar to that in a normal condition, but it differs from that in “sick” obesity, whereas the serum lipid patterns reflect the “liver-to-adipose-tissue DNL” ratio and are associated with the adipokinome signature.

MicroRNA-199a regulates myocardial fibrosis in rats by targeting SFRP5

OBJECTIVE

Myocardial fibrosis seriously affects normal heart function. This study focused on the role of microRNA-199a in regulating rat myocardial fibrosis by targeting secreted frizzled-related protein 5 (SFRP5).

MATERIALS AND METHODS

The in vitro myocardial fibrosis model was established by 10 μM isoproterenol (ISO) induction in cardiac fibroblasts (CFs) for 24 h. Expression levels of microRNA-199a, collagen I and α smooth muscle actin (α-SMA) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Protein levels of SFRP5 and transforming growth factor-β1 (TGF-β1) in CFs were detected by Western blot. The binding condition between microRNA-199a and SFRP5 was verified by luciferase reporter gene assay. After transfection of microRNA-199a inhibitor or SFRP5 overexpression plasmid, proliferative and migratory rates of CFs were determined by cell counting kit-8 (CCK-8) and transwell assay, respectively.

RESULTS

ISO treatment remarkably upregulated microRNA-199a expression in CFs. Transfection of microRNA-199a inhibitor could inhibit proliferation, migration and cardiac fibroblast-to-myofibroblast transformation (CMT) of CFs. Luciferase reporter gene assay confirmed the binding of microRNA-199a to SFRP5 3'UTR. Moreover, SFRP5 overexpression reversed the effects of microRNA-199a inhibitor on proliferation, migration, and CMT of CFs.

CONCLUSIONS

MicroRNA-199a deficiency can inhibit the proliferative and migratory potentials of CFs, as well as CMT by targeting SFRP5, thus exerting the protective effect on myocardial fibrosis.

Expression Levels of Predominant Adipokines and Activations of STAT3, STAT6 in an Experimental Mice Model of Obese Asthma

Obese asthma is a new asthma phenotype. The underlying mechanisms are not clearly understood. Leptin and adiponectin are two predominant adipokines produced by adipose tissue. Studies have demonstrated a role of leptin on regulating the Janus kinase/signal transducer and ativator of transcription protein (JAK/STAT) signaling pathway and STAT3, STAT6 were known to have essential role on inflammatory cytokines production. However, whether STAT3 and STAT6 are activated and related to leptin merit further investigation. The aim of this study was to investigate the expression levels of leptin/adiponectin ratio and the activations of STAT3 and STAT6 in the lungs of obese asthma mice. Experiments were carried out on male C57/B6J mice. The proteins in bronchoalveolar lavage fluid (BALF) were measured using ELISA. The expression levels of the transcriptional and translational factors in the lungs were examined using Quantitative Reverse Transcriptase Polymerase Chain reaction (qRT-PCR) and western blot. The expression levels of leptin in the BALF of normal weight group, asthma group, obese group and obese asthma group were 2.032±0.133, 5.375±0.123, 5.418±0.165 and 7.486±0.168, respectively. The expression of leptin in obese asthma group was the highest (p<0.05) ，while the expression of adiponectin the lowest (p<0.05). The expression level of P-STAT3 in the obese asthma group was 0.9244±0.014, and was significantly higher than three other groups (p<0.05). The expressions of P-STAT6 in three other groups were all significantly higher than normal weight group (p<0.05). Our data suggest that the function of leptin on the pulmonary inflammation of obese asthma may be partly through activating the STAT3 signaling pathway.

Prediction of Circulating Adipokine Levels Based on Body Fat Compartments and Adipose Tissue Gene Expression

BACKGROUND

Adipokines are hormones secreted from adipose tissue (AT), and a number of them have been established as risk factors for chronic diseases. However, it is not clear whether and to what extent adiposity, gene expression, and other factors determine their circulating levels.

OBJECTIVES

To assess to what extent adiposity, as measured by the amount of subcutaneous AT (SAT) and visceral AT (VAT) using magnetic resonance imaging, and gene expression levels in SAT determine plasma concentrations of the adipokines adiponectin, leptin, soluble leptin receptor, resistin, interleukin 6, and fatty acid-binding protein 4 (FABP4).

METHODS

We performed a cross-sectional analysis of 156 participants from the EPIC Potsdam cohort study and analyzed multiple regression models and partial correlation coefficients.

RESULTS

For leptin and FABP4 concentrations, 81 and 45% variance were explained by SAT mass, VAT mass, and gene expression in SAT in multivariable regression models. For the remaining adipokines, AT mass and gene expression explained <16% variance of plasma concentrations. Gene expression in SAT was a less important predictor compared to AT mass. SAT mass was a better predictor than VAT mass for leptin (partial correlation r = 0.81, 95% confidence interval 0.75-0.86, vs. r = 0.58, 95% confidence interval 0.46-0.67), while differences between AT compartments were small for the other adipokines.

CONCLUSIONS

While plasma levels of leptin and FABP4 can be explained in a large and medium part by the amount of AT and SAT gene expression, surprisingly, these predictors explained only little variance for all other investigated adipokines.

Sphingolipids in adipose tissue: What's tipping the scale?

Adipose tissue lies at the heart of obesity, mediating its many effects upon the rest of the body, with its unique capacity to expand and regenerate, throughout the lifespan of the organism. Adipose is appreciated as an endocrine organ, with its myriad adipokines that elicit both physiological and pathological outcomes. Sphingolipids, bioactive signaling molecules, affect many aspects of obesity and the metabolic syndrome. While sphingolipids are appreciated in the context of these diseases in other tissues, there are many discoveries yet to be uncovered in the adipose tissue. This review focuses on the effects of sphingolipids on various aspects of adipose function and dysfunction. The processes of adipogenesis, metabolism and thermogenesis, in addition to inflammation and insulin resistance are intimately linked to sphingolipids as discussed below.

Transgenic overexpression of CTRP3 prevents alcohol-induced hepatic triglyceride accumulation

This study tested the ability of a novel adipose tissue derived cytokine, C1q TNF-related protein-3 (CTRP3), to prevent alcohol-induced hepatic lipid accumulation, or alcoholic fatty liver disease (ALD). Previous work has demonstrated that CTRP3 is effective at preventing high-fat diet-induced fatty liver; however, the potential of CTRP3 to inhibit ALD has not been explored. To test the potential protective effects of CTRP3, transgenic mice overexpressing CTRP3 (Tg) or wild-type littermates (WT) were subjected to one of two different models of ALD. In the first model, known as the NIAAA model, mice were fed control or alcohol-containing liquid diets (5% vol/vol) for 10 days followed by a single gavage of ethanol (5 g/kg). In the second model, the chronic model, mice were fed control or alcohol-containing diets for 6 wk with no gavage. This study found that CTRP3 reduced triglyceride accumulation in the chronic model of alcohol consumption by ~50%, whereas no reduction was observed in the NIAAA model. Further analysis of isolated primary hepatocytes from WT and Tg mice demonstrated that CTRP3 increased oxygen consumption in the presence of fatty acids, indicating that CTRP3 increases hepatic fatty acid utilization. In conclusion, this study indicates that CTRP3 attenuates hepatic triglyceride accumulation in response to long-term chronic, but not short-term, alcohol consumption.

Adipokines expression profile in liver, adipose tissue and muscle during chicken embryo development

In broiler chickens, the intense genetic selection for rapid growth has resulted in an increase in growth rate and fat deposition. Adipose tissue is now recognized as an important endocrine organ that secretes a variety of factors including adipokines. However, the expression pattern of these adipokines is unclear in chicken embryo development. In the present study, we determined the expression profile of three novel adipokines, NAMPT, RARRES2 and ADIPOQ, and their cognate receptors in metabolic tissues (liver, muscles and adipose tissue) of chicken embryo/chicks from 15 days of incubation (E15) to hatching (D0). From E15 to hatching, embryos gradually gained weight and started to develop subcutaneous adipose tissue at E15. We conducted western blot and RT-qPCR tests and found that ADIPOQ expression increased over time and was positively correlated with adipose tissue weight. In addition, NAMPT expression increased only in muscles. By using a new homemade chicken RARRES2 specific antibody we showed that RARRES2 protein levels increased specifically at hatching in adipose tissue, liver and pectoralis major and this was associated with an increase in the weight of embryo. Taken together, these results support a potential involvement of adipokines in metabolic regulation during chicken embryo development.

Omentin Val/Val genotype increases predisposition to acne vulgaris without changing omentin serum level

Acne vulgaris is the most frequent and multifactorial inflammatory skin disorder in all races. Obesity is considered to be a risk factor for acne due to its contribution to inflammation. The involvements of inflammatory (leptin and resistin) and anti-inflammatory (adiponectin) adipokines in the pathogenesis of acne were reported. Omentin resembles adiponectin in terms of having inhibitory effect on tumor necrosis factor-α (TNF-α) induced inflammation, a vital process in the acne formation. This study was designed to investigate the putative involvement of omentin in acne formation. The genotyping was performed by restriction fragment length polymorphism (RFLP) method. Serum omentin protein levels were analyzed by enzyme-linked immunosorbent assay (ELISA). Serum omentin level was not significantly changed between groups. However, the decreased serum omentin level was observed as the mean value of BMI increased. The Asp/Asp, Val/Asp and Val/Val genotypes distributions for control and patient groups (19[17.4%], 22[20.2%], and 3[2.8%] respectively, vs. 31[28.4%], 25[22.9%], and 9[8.3%], respectively) were obtained. The Val/Val (mutant homozygote) genotype was found nearly 1.8 times more in the patient group (p=0.403, OR=1.839 (0.442-7.653)). This is the first time to clarify a linkage between anti-inflammatory omentin and acne vulgaris. Omentin Val109Asp polymorphism affects the overall function of the protein. In conclusion, omentin Val/Val (mutant homozygote) genotype increases predisposition to acne vulgaris by probably disrupting overall protein function of omentin.

Lower serum levels of Meteorin-like/Subfatin in patients with coronary artery disease and type 2 diabetes mellitus are negatively associated with insulin resistance and inflammatory cytokines

Meteorin-like (Metrnl) is a newly discovered adipokine with favorable effect on insulin sensitivity. Previous studies have reported lower levels of Metrnl in obese patients. However, there is conflicting data regarding its circulating levels in type 2 diabetes mellitus (T2DM) and there is no data in patients with coronary artery disease (CAD). The aim of the present study was to evaluate the Metrnl serum level in patients with T2DM and CAD, and also to evaluate the serum levels of Metrnl with serum levels of adiponectin, IL-6 and TNF-α in patients. This study was conducted on 66 patients with CAD, 63 T2DM patients and 41 controls. The serum levels of Metrnl, adiponectin, IL-6 and TNF-α were measured using ELISA techniques. The serum levels of Metrnl were found to be lower in CAD (75.18 ± 28.48 pg/mL) and T2DM patients (73.89 ± 33.60 pg/mL) compared to the control group (95.33 ± 32.56 pg/mL) (p < 0.005 and p<0.003, respectively). Additionally, adiponectin decreased in CAD and T2DM patients as compared to the control group, while IL-6 and TNF-α were higher in CAD and T2DM patients. Metrnl showed independent association with the risk of CAD and T2DM presence. Furthermore, Metrnl illustrated a negative correlation with IL-6 and TNF-α in both CAD patients and also with BMI, insulin resistance, IL-6 and TNF-α in T2DM patients. Metrnl showed an association with CAD and T2DM presence and with components of their pathogenesis such as inflammation and insulin resistance. These results suggested a possible interaction between Metrnl and the pathogenesis of CAD and T2DM, however more studies are needed to prove this concept.

Adipocytokine Regulation and Antiangiogenic Activity Underlie the Molecular Mechanisms of Therapeutic Effects of Phyllanthus niruri against Non-Alcoholic Fatty Liver Disease

The growth of adipose tissues is considered angiogenesis-dependent during non-alcoholic fatty liver disease (NAFLD). We have recently reported that our standardized 50% methanolic extract (ME) of Phyllanthus niruri (50% ME of P. niruri) has alleviated NAFLD in Sprague⁻Dawley rats. This study aimed to assess the molecular mechanisms of action, and to further evaluate the antiangiogenic effect of this extract. NAFLD was induced by eight weeks of high-fat diet, and treatment was applied for four weeks. Antiangiogenic activity was assessed by aortic ring assay and by in vitro tests. Our findings demonstrated that the therapeutic effects of 50% ME among NAFLD rats, were associated with a significant increase in serum adiponectin, reduction in the serum levels of RBP4, vaspin, progranulin, TNF-α, IL-6, and significant downregulation of the hepatic gene expression of PPARγ, SLC10A2, and Collα1. Concomitantly, 50% ME of P. niruri has exhibited a potent antiangiogenic activity on ring assay, cell migration, vascular endothelial growth factor (VEGF), and tube formation, without any cytotoxic effect. Together, our findings revealed that the protective effects of P. niruri against NAFLD might be attributed to its antiangiogenic effect, as well as to the regulation of adipocytokines and reducing the expression of adipogenic genes.

Thermogenic capacity of human periaortic adipose tissue is transformed by body weight

The anatomical location of adipose tissue might have direct implications for its functionality and risk of cardiovascular disease. Adipose tissue surrounding blood vessels may be thermogenically more active in specific areas of the body, releasing substances that regulate vascular metabolism. In humans, the phenotypic characteristics of adipose tissue surrounding the aorta and the cardiovascular disease risk that it might entail remain largely unknown. Here, we compared thermogenesis-related molecular features of human periaortic adipose tissue samples with those of subcutaneous adipose tissue, obtained by sternotomy from 42 patients undergoing cardiovascular surgery. To determine the expression of genes related to energy expenditure and the levels of some adipokines, histological examinations, quantitative PCR, and protein expression measurements in adipocyte precursor cells were performed. Periaortic adipocytes were smaller than those from subcutaneous tissue. Moreover, weight gain induced periaortic adipocyte hypertrophy (r = -0.91, p<0.01). Compared to subcutaneous tissue, adiponectin, FABP4, IL-4 and IL-6 was decreased in periaortic adipocytes, whereas FGF21, UCP-1, PGC-1a, CITED1, Omentin and TFAM (Mitochondrial protein) increased. Upon analyzing patients’ clinical conditions, it emerged that the levels of PGC-1a both in male (r = -0.48 p<0.04) and female (r = -0.61, p<0.05) and TFAM in male (r = -0.72, p<0.0008) and female (r = -0.86, p<0.002) decreased significantly with progressive weight gain. However, no differences were observed in patients with diabetes mellitus 2 or Hyperlipidemia. Adipocytes surrounding the ascending aorta present markers of major thermogenic activity than those in subcutaneous tissue. Nevertheless, this characteristic might change, due to unfavorable metabolic conditions such as obesity, which is a risk factor for cardiovascular disease.

Antiobesity molecular mechanisms of action: Resveratrol and pterostilbene

Obesity is a current global epidemic that has led to a marked increase in metabolic diseases. However, its treatment remains a challenge. Obesity is a multifactorial disease, which involves the dysfunction of neuropeptides, hormones, and inflammatory adipokines from the brain, gut, and adipose tissue. An understanding of the mechanisms and signal interactions in the crosstalk between organs and tissue in the coordination of whole-body energy metabolism would be helpful to provide therapeutic and putative approaches to the treatment and prevention of obesity and related complications. Resveratrol and pterostilbene are well-known stilbenes that provide various potential benefits to human health. In particular, their potential anti-obesity effects have been proven in numerous cell culture and animal studies. Both compounds act to regulate energy intake, adipocyte life cycle and function, white adipose tissue (WAT) inflammation, energy expenditure, and gut microbiota by targeting multiple molecules and signaling pathways as an intervention for obesity. Although the efficacy of both compounds in humans requires further investigation with respect to their oral bioavailability, promising scientific findings have highlighted their potential as candidates for the treatment of obesity and the improvement of obesity-related metabolic diseases. © 2018 BioFactors, 44(1):50-60, 2018.

[SECRETORY FUNCTION OF WHITE ADIPOSE TISSUE AND ADIPOKINES: BIOLOGICAL EFFECTS AND CLINICAL SIGNIFICANCE (REVIEW)]

In addition to accumulation and metabolism of triglycerides, white adipose tissue is recognized as the active endocrine organ, whose dysfunction is associated with the development of a wide range of diseases. The secretome of adipocytes is represented by a wide range of adipokines, which vary in depot and sex-specific manner. In addition, adipokines have diverse biological effects, correlations with different metabolic features and functions. In this review, the data on biological effects, origin and the clinical significance of adipokines are discussed. The influence of adipokines on metabolism, sensitivity to insulin, vascular homeostasis, angiogenesis, repair, inflammation and immune cells are shown. Visceral adipose tissue accumulation is accompanied with adipocytes hypertrophy and overproduction of such proinflammatory and proaterogenic molecules like resistin, visfatin, vaspin, tumor necrosis factor, interleukin 6, lipocalin, glypican 4, RBP4 etc. There is a tight correlation between these adipokines level and development of insulin resistance, type 2 diabetes, cardiometabolic complications and cancer. Thus, adipokines represent a group of informative biomarkers for the diagnostics of metabolic disorders and the prediction of the outcome of the wide range of diseases. The study of the effects and mechanisms of the action of adipokines is the basis for determining new targets for therapy.

Novel atherogenic pathways from the differential transcriptome analysis of diabetic epicardial adipose tissue

BACKGROUND AND AIM

To evaluate the epicardial adipose tissue (EAT) transcriptome in comparison to subcutaneous fat (SAT) in coronary artery disease (CAD) and type 2 diabetes (T2DM).

METHODS AND RESULTS

SAT and EAT samples were obtained from subjects with T2DM and CAD (n = 5) and those without CAD with or without T2DM (=3) undergoing elective cardiac surgery. RNA-sequencing analysis was performed in both EAT and SAT. Gene enrichment analysis was conducted to identify pathways affected by the differentially expressed genes. Changes of top genes were verified by quantitative RT-PCR (qRT-PCR), western blot, and immunofluorescence. A total of 592 genes were differentially expressed in diabetic EAT, whereas there was no obvious changes in SAT transcriptome between diabetics and non-diabetics. Diabetic EAT was mainly enriched in inflammatory genes, such as Colony Stimulating Factor 3 (CSF3), Interleukin-1b (IL-1b), IL-6. KEGG pathway analysis confirmed that upregulated genes were involved in inflammatory pathways, such as Tumor Necrosis Factor (TNF), Nuclear Factor-κB (NF-κB) and advanced glycation end-products-receptor advanced glycation end products (AGE-RAGE). The overexpression of inflammatory genes in diabetic EAT was largely correlated with upregulated transcription factors such as NF-κB and FOS.

CONCLUSIONS

Diabetic EAT transcriptome is significantly different when compared to diabetic SAT and highly enriched with genes involved in innate immune response and endothelium, like Pentraxin3 (PTX3) and Endothelial lipase G (LIPG). EAT inflammatory genes expression could be induced by upregulated transcription factors, mainly NF-kB and FOSL, primarily activated by the overexpressed AGE-RAGE signaling. This suggests a unique and novel atherogenic pathway in diabetes.

Fifty shades of white: Understanding heterogeneity in white adipose stem cells

The excessive expansion of white adipose tissue underlies the global obesity epidemic. However, not all fat is equal, and the impact of heterogeneity on the development and expansion of different adipose depots is becoming increasingly apparent. Two mechanisms are responsible for the growth of adipose tissue: hyperplasia (increasing adipocyte number) and hypertrophy (increasing adipocyte size). The former relies on the differentiation of adipocyte stem cells, which reside within the adipose stromal vascular fraction. Many differences in gene expression, adipogenesis, and the response to obesogenic stimuli have been described when comparing adipose stem cells from different depots. Considering that there is disparity in the pathogenicity of the depots, understanding this heterogeneity has clinically relevant implications. Here we review the current knowledge surrounding such differences, in the context of development, expansion and therapeutics. Moreover, given the importance of these differences, we suggest that careful consideration for the precise methodologies used, is essential if we are to truly understand the physiologically relevant consequences of this heterogeneity.

CTRP3 attenuates cardiac dysfunction, inflammation, oxidative stress and cell death in diabetic cardiomyopathy in rats

AIMS/HYPOTHESIS

Oxidative stress, inflammation and cell death are closely involved in the development of diabetic cardiomyopathy (DCM). C1q/tumour necrosis factor-related protein-3 (CTRP3) has anti-inflammatory properties but its role in DCM remains largely unknown. The aims of this study were to determine whether CTRP3 could attenuate DCM and to clarify the underlying mechanisms.

METHODS

Streptozotocin (STZ) was injected intraperitoneally to induce diabetes in Sprague-Dawley rats. Cardiomyocyte-specific CTRP3 overexpression was achieved using an adeno-associated virus system 12 weeks after STZ injection.

RESULTS

CTRP3 expression was significantly decreased in diabetic rat hearts. Knockdown of CTRP3 in cardiomyocytes at baseline resulted in increased oxidative injury, inflammation and apoptosis in vitro. Cardiomyocyte-specific overexpression of CTRP3 decreased oxidative stress and inflammation, attenuated myocyte death and improved cardiac function in rats treated with STZ. CTRP3 significantly activated AMP-activated protein kinase α (AMPKα) and Akt (protein kinase B) in H9c2 cells. CTRP3 protected against high-glucose-induced oxidative stress, inflammation and apoptosis in vitro. AMPKα deficiency abolished the protective effects of CTRP3 in vitro and in vivo. Furthermore, we found that CTRP3 activated AMPKα via the cAMP-exchange protein directly activated by cAMP (EPAC)-mitogen-activated protein kinase kinase (MEK) pathway.

CONCLUSIONS/INTERPRETATION

CTRP3 protected against DCM via activation of the AMPKα pathway. CTRP3 has therapeutic potential for the treatment of DCM.

Brown adipose tissue (BAT) specific vaspin expression is increased after obesogenic diets and cold exposure and linked to acute changes in DNA-methylation

OBJECTIVE

Several studies have demonstrated anti-diabetic and anti-obesogenic properties of visceral adipose tissue-derived serine protease inhibitor (vaspin) and so evoked its potential use for treatment of obesity-related diseases. The aim of the study was to unravel physiological regulators of vaspin expression and secretion with a particular focus on its role in brown adipose tissue (BAT) biology.

METHODS

We analyzed the effects of obesogenic diets and cold exposure on vaspin expression in liver and white and brown adipose tissue (AT) and plasma levels. Vaspin expression was analyzed in isolated white and brown adipocytes during adipogenesis and in response to adrenergic stimuli. DNA-methylation within the vaspin promoter was analyzed to investigate acute epigenetic changes after cold-exposure in BAT.

RESULTS

Our results demonstrate a strong induction of vaspin mRNA and protein expression specifically in BAT of both cold-exposed and high-fat (HF) or high-sugar (HS) fed mice. While obesogenic diets also upregulated hepatic vaspin mRNA levels, cold exposure tended to increase vaspin gene expression of inguinal white adipose tissue (iWAT) depots. Concomitantly, vaspin plasma levels were decreased upon obesogenic or thermogenic triggers. Vaspin expression was increased during adipogenesis but unaffected by sympathetic activation in brown adipocytes. Analysis of vaspin promoter methylation in AT revealed lowest methylation levels in BAT, which were acutely reduced after cold exposure.

CONCLUSIONS

Our data demonstrate a novel BAT-specific regulation of vaspin gene expression upon physiological stimuli in vivo with acute epigenetic changes that may contribute to cold-induced expression in BAT. We conclude that these findings indicate functional relevance and potentially beneficial effects of vaspin in BAT function.

Supervised Clustering of Adipokines and Hormonal Receptors Predict Prognosis in a Population of Obese Women with Type 1 Endometrial Cancer

Obesity is a major risk factor for endometrial cancer (EC). Yet, its impact on prognosis is controversial. Obesity is associated with metabolic and hormonal dysregulation as well as adipokines increase. The aim of this study was to characterize the expression of biological factors related to obesity within the tumor and evaluate their impact on prognosis. One hundred and thirty-six patients, including 55 obese patients, with endometrioid type I EC operated by total hysterectomy were included in this retrospective study conducted in a Tertiary teaching hospital between 2000 and 2013. Immunohistochemistry (IHC) study was performed on type I EC tumor samples using five adipokines (SPARC, RBP4 (Retinol Binding Protein 4), adiponectin, TNF α, IL-6) and hormonal receptors (estrogen receptor and progesterone receptor). Supervised clustering of immunohistochemical markers was performed to identify clusters that could be associated with prognostic groups. The prognosis of the obese population was not different from the prognosis of the general population. Adipokine expression within tumors was not different in these two populations. In obese population, we found three clusters where co-expression was associated with a recurrence group in comparison with a non-recurrence group and four clusters where co-expression was associated with the high risk FIGO (International Federation of Gynecology and Obstetrics) stage I group in comparison of low risk FIGO stage I group. While obesity does not appear as a prognostic factor in endometrioid type I EC, the co-expression of biological factors in IHC on hysterectomy specimens allowed to distinguish two prognostic groups in obese population.

Translating the biology of adipokines in atherosclerosis and cardiovascular diseases: Gaps and open questions

AIM

Critically discuss the available data, to identify the current gaps and to provide key concepts that will help clinicians in translating the biology of adipokines in the context of atherosclerosis and cardio-metabolic diseases.

DATA SYNTHESIS

Adipose tissue is nowadays recognized as an active endocrine organ, a function related to the ability to secrete adipokines (such as leptin and adiponectin) and pro-inflammatory cytokines (tumor necrosis factor alpha and resistin). Studies in vitro and in animal models have observed that obesity status presents a chronic low-grade inflammation as the consequence of the immune cells infiltrating the adipose tissue as well as adipocytes. This inflammatory signature is often related to the presence of cardiovascular diseases, including atherosclerosis and thrombosis. These links are less clear in humans, where the role of adipokines as prognostic marker and/or player in cardiovascular diseases is not as clear as that observed in experimental models. Moreover, plasma adipokine levels might reflect a condition of adipokine-resistance in which adipokine redundancy occurs. The investigation of the cardio-metabolic phenotype of carriers of single nucleotide polymorphisms affecting the levels or function of a specific adipokine might help determine their relevance in humans. Thus, the aim of the present review is to critically discuss the available data, identify the current gaps and provide key concepts that will help clinicians translate the biology of adipokines in the context of atherosclerosis and cardio-metabolic diseases.

Adipose tissue: an endocrine organ playing a role in metabolic regulation

Adipose tissue is a complex endocrine organ with an intricate role in whole body homeostasis. Beyond storing energy, adipose tissue is fundamental in numerous processes including, but not limited to, metabolism, food intake and immune cell function. Adipokines and cytokines are the signaling factors from adipose tissue. These factors play a role in maintaining health, but are also candidates for pathologies associated with obesity. Indeed excessive adiposity causes dysregulation of these factors which negatively affect health and contribute to numerous obesity-induced co-morbidities. In particular, adipokines are fundamental in regulation of glucose homeostasis and insulin signaling, thus aberrant production of these adipose derived hormones correlates with the development and progression of type 2 diabetes. Therefore, elucidation of adipose regulation is crucial for understanding the pathophysiological basis of obesity and metabolic diseases such as type 2 diabetes. In the present review, we summarize current data on the relation between adipokines and adipose depot derived cytokines in the maintenance of glucose homeostasis. Specifically, physiological and molecular functions of several adipokines are defined with particular focus on interactions within the insulin-signaling pathway and subsequent regulation of glucose uptake in both standard and obesity-induced dysregulated conditions. This same relation will be discussed for cytokines and inflammation as well.

C1q/TNF-related protein 1 prevents neointimal formation after arterial injury

BACKGROUND AND AIMS

Obesity contributes to the progression of vascular disorders. C1q/TNF-related protein (CTRP) 1 is a circulating adipokine, which is upregulated in obese complications including coronary artery disease. Here, we investigated the role of CTRP1 in regulation of vascular remodeling after mechanical injury and evaluated its potential mechanism.

METHODS

Mice were subjected to wire-induced injury of left femoral arteries. An adenoviral vector encoding CTRP1 (Ad-CTRP1) or β-galactosidase as a control was injected into the jugular vein of mice 3 days prior to surgery.

RESULTS

Systemic administration of Ad-CTRP1 to wild-type mice led to reduction of the neointimal thickening after wire-induced arterial injury and the number of bromodeoxyuridine-positive cells in injured vessels as compared with treatment with control vectors. Treatment of vascular smooth muscle cells (VSMCs) with CTRP1 protein attenuated proliferative activity and ERK phosphorylation in response to PDGF-BB. CTRP1 treatment increased cyclic AMP (cAMP) levels in VSMCs, and inhibition of adenylyl cyclase reversed the inhibitory effect of CTRP1 on VSMC growth and ERK phosphorylation. Antagonization of sphingosine-1-phosphaterote (S1P) receptor 2 blocked the effects of CTRP1 on cAMP production and VSMC growth. Furthermore, CTRP1-knockout mice had enhanced neointimal thickening following injury and increased numbers of proliferating cells in neointima compared to control WT mice.

CONCLUSIONS

These findings indicate that CTRP1 functions to prevent the development of pathological vascular remodeling by reducing VSMC growth through the cAMP-dependent pathway.

Metabolic Adaptation in Obesity and Type II Diabetes: Myokines, Adipokines and Hepatokines

Obesity and type II diabetes are characterized by insulin resistance in peripheral tissues. A high caloric intake combined with a sedentary lifestyle is the leading cause of these conditions. Whole-body insulin resistance and its improvement are the result of the combined actions of each insulin-sensitive organ. Among the fundamental molecular mechanisms by which each organ is able to communicate and engage in cross-talk are cytokines or peptides which stem from secretory organs. Recently, it was reported that several cytokines or peptides are secreted from muscle (myokines), adipose tissue (adipokines) and liver (hepatokines) in response to certain nutrition and/or physical activity conditions. Cytokines exert autocrine, paracrine or endocrine effects for the maintenance of energy homeostasis. The present review is focused on the relationship and cross-talk amongst muscle, adipose tissue and the liver as secretory organs in metabolic diseases.

Brief Report: Association of Adipokines With Bone Mineral Density in HIV-Infected and HIV-Uninfected Women

BACKGROUND

HIV infection is associated with low bone mineral density (BMD) and alterations in adipokines, which may mediate the relationship between fat and bone.

OBJECTIVE

To evaluate the relationship of adiponectin and leptin with BMD in HIV-infected and uninfected women.

METHODS

We measured BMD over 5 years at the lumbar spine, total hip (TH), and femoral neck (FN) using dual-energy X-ray absorptiometry in 318 HIV-infected and 122 HIV-uninfected participants of the multicenter Women's Interagency HIV Study (WIHS). Total adiponectin and leptin were assayed on stored sera. Multivariable linear mixed models assessed the effects of adipokines and HIV status on BMD.

RESULTS

HIV-infected women had higher adiponectin (median 6.2 vs. 5.6 μg/mL,) but lower leptin (11.7 vs. 19.8 ng/mL) levels at baseline (both P < 0.05) compared with HIV-uninfected women. HIV infection was associated with lower BMD at the lumbar spine (-0.074 g/cm), FN (-0.049 g/cm), and TH (-0.047 g/cm) (all P < 0.05) after adjusting for demographic, behavioral, and metabolic factors. HIV infection remained associated with lower BMD at each site, with little change in the effect sizes after additional adjustment for adiponectin or leptin. Among HIV-infected women, higher adiponectin was associated with lower TH BMD (-0.025 g/cm per 10-fold increase, P = 0.035), whereas higher leptin was associated with higher BMD at FN (+0.027 g/cm per 10-fold increase, P = 0.005) and TH (+0.019 g/cm, P = 0.028). After multivariable adjustment, the adipokines showed little association with BMD at any site (P > 0.8 for adiponectin; P > 0.2 for leptin).

CONCLUSIONS

Alterations in serum adiponectin and leptin do not explain low BMD in HIV-infected women.

CST, an Herbal Formula, Exerts Anti-Obesity Effects through Brain-Gut-Adipose Tissue Axis Modulation in High-Fat Diet Fed Mice

The brain, gut, and adipose tissue interact to control metabolic pathways, and impairment in the brain-gut-adipose axis can lead to metabolic disorders, including obesity. Chowiseungcheng-tang (CST), a herbal formulation, is frequently used to treat metabolic disorders. Here, we investigated the anti-obesity effect of CST and its link with brain-gut-adipose axis using C57BL/6J mice as a model. The animals were provided with a normal research diet (NRD) or high-fat diet (HFD) in absence or presence of CST or orlistat (ORL) for 12 weeks. CST had a significant anti-obesity effect on a number of vital metabolic and obesity-related parameters in HFD-fed mice. CST significantly decreased the expression levels of genes encoding obesity-promoting neuropeptides (agouti-related peptide, neuropeptide Y), and increased the mRNA levels of obesity-suppressing neuropeptides (proopiomelanocortin, cocaine-and amphetamine-regulated transcript) in the hypothalamus. CST also effectively decreased the expression level of gene encoding obesity-promoting adipokine (retinol-binding protein-4) and increased the mRNA level of obesity-suppressing adipokine (adiponectin) in visceral adipose tissue (VAT). Additionally, CST altered the gut microbial composition in HFD groups, a phenomenon strongly associated with key metabolic parameters, neuropeptides, and adipokines. Our findings reveal that the anti-obesity impact of CST is mediated through modulation of metabolism-related neuropeptides, adipokines, and gut microbial composition.

[C1q/tumor necrosis factor related protein 6 (CTRP6) is involved in gentamicin-induced acute kidney injury in rats]

Objective To explore the role of the anti-inflammatory cytokine C1q/tumor necrosis factor related protein 6 (CTRP6) in gentamicin-induced acute kidney injury in rats. Methods SD rats were divided into 5 groups including control group, model group and the other 3 experimental groups. The rats in model group and experimental groups were subcutaneously injected with gentamicin at the dose of 400 mg/(kg.d) for consecutive 2 days to induce acute renal injury. Two days before gentamicin injection, the rats in the 3 experimental groups were given pAd-CTRP6 at the doses of 0.5, 5 and 50 mg/kg, respectively. The serum levels of blood urea nitrogen (BUN) and creatinine (Cr) were respectively assayed with picric acid colorimetry and ultraviolet spectrophotometry; ELISA was used to detect serum CTRP6 content and the production of interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) in the kidney homogenate; Western blotting was performed to detect the expressions of CTRP6, caspase-1 and pyrin domain containing 3 (NLRP3) proteins in the renal tissues of rats. Results Compared with control group, serum BUN and Cr contents increased in the model rats; the secretion of inflammatory factors IL-1β and TNF-α, as well as the expressions of caspase-1 and NLRP3 were also enhanced in the model group. Compared with the model group, serum BUN and Cr contents decreased in the experimental groups; the secretion of IL-1β and TNF-α, as well as the expressions of caspase-1 and NLRP3 were also attenuated in the experimental groups. Moreover, with the increase of the injection dosage of pAd-CTRP6, the suppressive effect was gradually strengthened. Conclusion CTRP6 can attenuate gentamicin-induced acute renal injury in rats in a dose-dependent manner.