Free fatty acids normalize a rosiglitazone-induced visfatin release

Comparing the prolonged effect of interval versus continuous aerobic exercise on blood inflammatory marker of Visfatin level and body mass index of sedentary overweigh/fat female college students

History and objectives

Over weightiness and obesity are usually defined as inflammatory conditions. High ratio of body mass index and Visfatin level recently discovered as markers involved in inflammatory process of obesity. Aerobic exercise is one of the safe interventions to decrease such condition. The purpose of this research was to compare the effect of interval versus continuous aerobic exercise on Visfatin and BMI of sedentary overweight female college students.

Materials and Methods

Thirty-six healthy sedentary overweight female college students with BMI over 25 or more were randomly assigned into three groups including continuous, interval aerobic exercise and control conditions for eight weeks, three sessions per week. Serum visfatin level was assessed before and after the exercise protocol. The exercise protocol included running a distance of 1200 meters continuously or with rest intervals at 60 to 75 percent of reserved heart rate in the first week that gradually increased by 400 meters on every subsequent week.

Results

Our study indicated that both aerobic exercise conditions significantly decrease the serum level of visfatin (P = 0.000, P = 0.025, respectively). Both exercise groups also showed a decrease in BMI compared to the control group (P = 0.006, P = 0.004).

Conclusion

Aerobic exercise has a beneficiary effect on both serum visfatin level and BMI variables involved in inflammation process of obesity regardless of being performed with rest interval or continuously.

Extracellular nicotinamide phosphoribosyltransferase, a new cancer metabokine

In this review, we focus on the secreted form of nicotinamide phosphoribosyltransferase (NAMPT); extracellular NAMPT (eNAMPT), also known as pre-B cell colony-enhancing factor or visfatin. Although intracellular NAMPT is a key enzyme in controlling NAD metabolism, eNAMPT has been reported to function as a cytokine, with many roles in physiology and pathology. Circulating eNAMPT has been associated with several metabolic and inflammatory disorders, including cancer. Because cytokines produced in the tumour micro-environment play an important role in cancer pathogenesis, in part by reprogramming cellular metabolism, future improvements in cancer immunotherapy will require a better understanding of the crosstalk between cytokine action and tumour biology. In this review, the knowledge of eNAMPT in cancer will be discussed, focusing on its immunometabolic function as a metabokine, its secretion, its mechanism of action and possible roles in the cancer micro-environment.

Impact of metformin treatment and swimming exercise on visfatin levels in high-fat-induced obesity rats

Objective : Visfatin is a recently discovered adipocytokine that contributes to glucose and obesity-related conditions. Until now, its responses to the insulin-sensitizing agent metformin and to exercise are largely unknown. We aim to investigate the impact of metformin treatment and/or swimming exercise on serum visfatin and visfatin levels in subcutaneous adipose tissue (SAT), peri-renal adipose tissue (PAT) and skeletal muscle (SM) of high-fat-induced obesity rats. Materials and methods : Sprague-Dawley rats were fed a normal diet or a high-fat diet for 16 weeks to develop obesity model. The high-fat-induced obesity model rats were then randomized to metformin (MET), swimming exercise (SWI), or adjunctive therapy of metformin and swimming exercise (MAS), besides high-fat obesity control group and a normal control group, all with 10 rats per group. Zoometric and glycemic parameters, lipid profile, and serum visfatin levels were assessed at baseline and after 6 weeks of therapy. Visfatin levels in SAT, PAT and SM were determined by Western Blot. Results : Metformin and swimming exercise improved lipid profile, and increased insulin sensitivity and body weight reduction were observed. Both metformin and swimming exercise down-regulated visfatin levels in SAT and PAT, while the adjunctive therapy conferred greater benefits, but no changes of visfatin levels were observed in SM. Conclusion : Our results indicate that visfatin down-regulation in SAT and PAT may be one of the mechanisms by which metformin and swimming exercise inhibit obesity.

Metabolic syndrome and insulin resistance: underlying causes and modification by exercise training

Metabolic syndrome (MS) is a collection of cardiometabolic risk factors that includes obesity, insulin resistance, hypertension, and dyslipidemia. Although there has been significant debate regarding the criteria and concept of the syndrome, this clustering of risk factors is unequivocally linked to an increased risk of developing type 2 diabetes and cardiovascular disease. Regardless of the true definition, based on current population estimates, nearly 100 million have MS. It is often characterized by insulin resistance, which some have suggested is a major underpinning link between physical inactivity and MS. The purpose of this review is to: (i) provide an overview of the history, causes and clinical aspects of MS, (ii) review the molecular mechanisms of insulin action and the causes of insulin resistance, and (iii) discuss the epidemiological and intervention data on the effects of exercise on MS and insulin sensitivity.

Regulation of cell survival and death by pyridine nucleotides

Pyridine nucleotides (PNs), such as NAD(H) and NADP(H), mediate electron transfer in many catabolic and anabolic processes. In general, NAD(+) and NADP(+) receive electrons to become NADH and NADPH by coupling with catabolic processes. These electrons are utilized for biologically essential reactions such as ATP production, anabolism and cellular oxidation-reduction (redox) regulation. Thus, in addition to ATP, NADH and NADPH could be defined as high-energy intermediates and "molecular units of currency" in energy transfer. We discuss the significance of PNs as energy/electron transporters and signal transducers, in regulating cell death and/or survival processes. In the first part of this review, we describe the role of NADH and NADPH as electron donors for NADPH oxidases (Noxs), glutathione (GSH), and thioredoxin (Trx) systems in cellular redox regulation. Noxs produce superoxide/hydrogen peroxide yielding oxidative environment, whereas GSH and Trx systems protect against oxidative stress. We then describe the role of NAD(+) and NADH as signal transducers through NAD(+)-dependent enzymes such as PARP-1 and Sirt1. PARP-1 is activated by damaged DNA in order to repair the DNA, which attenuates energy production through NAD(+) consumption; Sirt1 is activated by an increased NAD(+)/NADH ratio to facilitate signal transduction for metabolic adaption as well as stress responses. We conclude that PNs serve as an important interface for distinct cellular responses, including stress response, energy metabolism, and cell survival/death.

Assessment of serum visfatin levels in girls with anorexia nervosa

OBJECTIVE

Visfatin (VISF) is a recently described peptide regulating the process of adipocyte differentiation. Only one pilot study of VISF expression in the fat tissue and its circulating concentrations in a small group of patients with anorexia nervosa (AN) have been published, yet.

DESIGN AND PATIENTS

Cross-sectional assessment of VISF serum concentrations in 195 girls aged 11-18·9 years with AN (n = 87), eating disorders not otherwise specified (NOS; n = 17), simple obesity (OB; n = 30), and healthy controls (H; n = 61).

MEASUREMENTS

Blood samples were collected during the fasting state between 7:00 am-8:30 am. VISF serum concentrations were determined using enzyme immunoassay. Comparisons of VISF levels between groups were performed.

RESULTS

Mean serum VISF concentrations in girls with AN and NOS were significantly lower than those in the H and OB groups. Serum VISF concentrations were higher in the OB than in the H groups. When were calculated per body mass index (BMI), VISF concentrations were significantly lower in the AN, NOS, and OB groups than in healthy controls. Among participants with a normal BMI, serum VISF concentrations correlated positively with BMI (r = 0·27; P < 0·05). In the OB group, a significant, negative correlation between BMI and VISF levels (r = -0·38; P = 0·04) was observed.

CONCLUSIONS

Compared with healthy girls, serum VISF concentrations are decreased in girls with AN. Conversely, obese girls have elevated VISF levels. When calculated per BMI (VISF/BMI), the results in AN and OB groups were lower than in healthy participants.

Visfatin is regulated by rosiglitazone in type 2 diabetes mellitus and influenced by NFκB and JNK in human abdominal subcutaneous adipocytes

Visfatin has been proposed as an insulin-mimicking adipocytokine, predominantly secreted from adipose tissue and correlated with obesity. However, recent studies suggest visfatin may act as a proinflammatory cytokine. Our studies sought to determine the significance of this adipocytokine and its potential role in the pathogenesis of T2DM. Firstly, we examined the effects of diabetic status on circulating visfatin levels, and several other adipocytokines, demonstrating that diabetic status increased visfatin*, TNF-α*** and IL-6*** compared with non-diabetic subjects (*p<0.05, **p<0.01, ***p<0.001, respectively). We then assessed the effects of an insulin sensitizer, rosiglitazone (RSG), in treatment naïve T2DM subjects, on circulating visfatin levels. Our findings showed that visfatin was reduced post-RSG treatment [vs. pre-treatment (*p<0.05)] accompanied by a reduction in HOMA-IR**, thus implicating a role for insulin in visfatin regulation. Further studies addressed the intracellular mechanisms by which visfatin may be regulated, and may exert pro-inflammatory effects, in human abdominal subcutaneous (Abd Sc) adipocytes. Following insulin (Ins) and RSG treatment, our in vitro findings highlighted that insulin (100 nM), alone, upregulated visfatin protein expression whereas, in combination with RSG (10 nM), it reduced visfatin*, IKKβ** and p-JNK1/2*. Furthermore, inhibition of JNK protein exacted a significant reduction in visfatin expression (**p<0.01), whilst NF-κB blockade increased visfatin (*p<0.05), thus identifying JNK as the more influential factor in visfatin regulation. Additional in vitro analysis on adipokines regulating visfatin showed that only Abd Sc adipocytes treated with recombinant human (rh)IL-6 increased visfatin protein (*p<0.05), whilst rh visfatin treatment, itself, had no influence on TNF-α, IL-6 or resistin secretion from Sc adipocytes. These data highlight visfatin's regulation by insulin and RSG, potentially acting through NF-κB and JNK mechanisms, with only rh IL-6 modestly affecting visfatin regulation. Taken together, these findings suggest that visfatin may represent a pro-inflammatory cytokine that is influenced by insulin/insulin sensitivity via the NF-κB and JNK pathways.

Circulating visfatin levels in healthy preterm infants are independently associated with high-density lipoprotein cholesterol levels and dietary long-chain polyunsaturated fatty acids

The adipokine visfatin has been proposed to exert insulin-mimicking effects and to play a role in the development of metabolic syndrome. Preterm infants are at risk for the later development of insulin resistance and, possibly, for other components of metabolic syndrome. Dietary long-chain polyunsaturated fatty acids (LCPUFAs) during the perinatal period may reduce the risk of metabolic syndrome. The authors' objective was to study the circulating concentrations of visfatin in preterm infants and to examine associations of visfatin with anthropometric measurements, metabolic indices, and dietary LCPUFAs. Serum visfatin concentrations were determined by enzyme-linked immunosorbent assay at mean (SD) 33.8 (11.7) days of life in 60 healthy preterm infants (gestational age, 32.7 [1.9] weeks) randomly assigned to be fed since birth either a formula containing LCPUFA (arachidonic and docosahexaenoic acid) (+LCPUFA group) or the same formula without LCPUFA (-LCPUFA group). Associations of visfatin with anthropometric parameters, serum glucose, insulin, homeostasis model assessment index of insulin resistance, blood lipids, and adiponectin levels were examined. Serum visfatin levels were significantly higher in the +LCPUFA than in the -LCPUFA group (P < .001) and correlated positively with body weight z score (β = 0.31, P = .02), total cholesterol (β = 0.34, P = .01), high-density lipoprotein cholesterol (HDL-C) (β = 0.47, P < .001), and adiponectin levels (β = 0.29, P = .03), but not with indices of insulin sensitivity. In multiple regression analysis, HDL-C and dietary LCPUFAs correlated independently with serum visfatin levels. Circulating visfatin levels in preterm infants are independently associated with HDL-C levels and dietary LCPUFAs. Whether the higher visfatin levels in the +LCPUFA preterm infant group are beneficial for the later health of these infants remains to be determined.

Visfatin is induced by peroxisome proliferator-activated receptor gamma in human macrophages

Obesity is a low-grade chronic inflammatory disease associated with an increased number of macrophages (adipose tissue macrophages) in adipose tissue. Within the adipose tissue, adipose tissue macrophages are the major source of visfatin/pre-B-cell colony-enhancing factor/nicotinamide phosphoribosyl transferase. The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) exerts anti-inflammatory effects in macrophages by inhibiting cytokine production and enhancing alternative differentiation. In this study, we investigated whether PPARgamma modulates visfatin expression in murine (bone marrow-derived macrophage) and human (primary human resting macrophage, classical macrophage, alternative macrophage or adipose tissue macrophage) macrophage models and pre-adipocyte-derived adipocytes. We show that synthetic PPARgamma ligands increase visfatin gene expression in a PPARgamma-dependent manner in primary human resting macrophages and in adipose tissue macrophages, but not in adipocytes. The threefold increase of visfatin mRNA was paralleled by an increase of protein expression (30%) and secretion (30%). Electrophoretic mobility shift assay experiments and transient transfection assays indicated that PPARgamma induces visfatin promoter activity in human macrophages by binding to a DR1-PPARgamma response element. Finally, we show that PPARgamma ligands increase NAD(+) production in primary human macrophages and that this regulation is dampened in the presence of visfatin small interfering RNA or by the visfatin-specific inhibitor FK866. Taken together, our results suggest that PPARgamma regulates the expression of visfatin in macrophages, leading to increased levels of NAD(+).

Regulation of adipokine secretion by n-3 fatty acids

Obesity leads to several chronic morbidities including type 2 diabetes, dyslipidaemia, atherosclerosis and hypertension, which are major components of the metabolic syndrome. White adipose tissue (WAT) metabolism and WAT-derived factors (fatty acids and adipokines) play an important role in the development of these metabolic disturbances. In fact, dysregulated adipokine secretion from the expanded WAT of obese individuals contributes to the development of systemic low-grade inflammation, insulin resistance and metabolic syndrome. The n-3 PUFA EPA and DHA have been widely reported to have protective effects in a range of chronic inflammatory conditions including obesity. In fact, n-3 PUFA have been shown to ameliorate low-grade inflammation in adipose tissue associated with obesity and up-regulate mitochondrial biogenesis and induce beta-oxidation in WAT in mice. Moreover, the ability of n-3 PUFA to regulate adipokine gene expression and secretion has been observed both in vitro and in vivo in rodents and human subjects. The present article reviews: (1) the physiological role of adiponectin, leptin and pre-B cell colony-enhancer factor/visfatin, three adipokines with immune-modulatory properties involved in the regulation of metabolism and insulin sensitivity and (2) the actions of n-3 PUFA on these adipokines focusing on the underlying mechanisms and the potential relationship with the beneficial effects of these fatty acids on obesity-associated metabolic disorders. It can be concluded that the ability of n-3 PUFA to improve obesity and insulin resistance conditions partially results from the modulation of WAT metabolism and the secretion of bioactive adipokines including leptin, adiponectin and visfatin.

Visfatin, glucose metabolism and vascular disease: a review of evidence

The adipose tissue is an endocrine organ producing substances called adipocytokines that have different effects on lipid metabolism, metabolic syndrome, and cardiovascular risk. Visfatin was recently described as an adipocytokine with potentially important effects on glucose metabolism and atherosclerosis. Visfatin has been linked to several inflammatory conditions, beta cell function, and cardiovascular disease. The growing number of publications on the subject shall bring further evidence about this adipocytokine. Its findings may contribute in the identification of higher risk individuals for diabetes and cardiovascular disease with a better comprehension about the complex intercorrelation between adiposity, glucose metabolism and vascular disease.

Eicosapentaenoic acid stimulates AMP-activated protein kinase and increases visfatin secretion in cultured murine adipocytes

Visfatin is an adipokine highly expressed in visceral AT (adipose tissue) of humans and rodents, the production of which seems to be dysregulated in excessive fat accumulation and conditions of insulin resistance. EPA (eicosapentaenoic acid), an n-3 PUFA (polyunsaturated fatty acid), has been demonstrated to exert beneficial effects in obesity and insulin resistance conditions, which have been further linked to its reported ability to modulate adipokine production by adipocytes. TNF-alpha (tumour necrosis factor-alpha) is a pro-inflammatory cytokine whose production is increased in obesity and is involved in the development of insulin resistance. Control of adipokine production by some insulin-sensitizing compounds has been associated with the stimulation of AMPK (AMP-activated protein kinase). The aim of the present study was to examine in vitro the effects of EPA on visfatin production and the potential involvement of AMPK both in the absence or presence of TNF-alpha. Treatment with the pro-inflammatory cytokine TNF-alpha (1 ng/ml) did not modify visfatin gene expression and protein secretion in primary cultured rat adipocytes. However, treatment of these primary adipocytes with EPA (200 mumol/l) for 24 h significantly increased visfatin secretion (P<0.001) and mRNA gene expression (P<0.05). Moreover, the stimulatory effect of EPA on visfatin secretion was prevented by treatment with the AMPK inhibitor Compound C, but not with the PI3K (phosphoinositide 3-kinase) inhibitor LY294002. Similar results were observed in 3T3-L1 adipocytes. Moreover, EPA strongly stimulated AMPK phosphorylation alone or in combination with TNF-alpha in 3T3-L1 adipocytes and pre-adipocytes. The results of the present study suggest that the stimulatory action of EPA on visfatin production involves AMPK activation in adipocytes.

Metabolic preconditioning of donor organs: defatting fatty livers by normothermic perfusion ex vivo

Fatty liver is a significant risk factor for liver transplantation, and accounts for nearly half of the livers rejected from the donor pool. We hypothesized that metabolic preconditioning via ex vivo perfusion of the liver graft can reduce fat content and increase post-transplant survival to an acceptable range. We describe a perfusate medium containing agents that promote the defatting of hepatocytes and explanted livers. Defatting agents were screened on cultured hepatocytes made fatty by pre-incubation with fatty acids. The most effective agents were then used on fatty livers. Fatty livers were isolated from obese Zucker rats and normothermically perfused with medium containing a combination of defatting agents. This combination decreased the intracellular lipid content of cultured hepatocytes by 35% over 24h, and of perfused livers by 50% over 3h. Metabolite analysis suggests that the defatting cocktail upregulated both lipid oxidation and export. Furthermore, gene expression analysis for several enzymes and transcription factors involved in fatty acid oxidation and triglyceride clearance were elevated. We conclude that a cocktail of defatting agents can be used to rapidly clear excess lipid storage in fatty livers, thus providing a new means to recondition donor livers deemed unacceptable or marginally acceptable for transplantation.

Visfatin/PBEF/Nampt: structure, regulation and potential function of a novel adipokine

Over the last few years, it has become obvious that obesity and insulin resistance are linked by a variety of proteins secreted by adipocytes. Visfatin/PBEF (pre-B-cell colony-enhancing factor) has recently been identified as a novel adipokine with insulin-mimetic effects. Furthermore, an enzymatic function has been reported that reveals visfatin/PBEF as Nampt (nicotinamide phosphoribosyltransferase; EC 2.4.2.12.). Moreover, reports on the structure and hormonal regulation of visfatin/PBEF/Nampt have given further insights into its potential physiological role. The present review summarizes studies on visfatin/PBEF/Nampt as a novel adipokine.

Angiotensin inhibition stimulates PPARgamma and the release of visfatin

BACKGROUND

Angiotensin converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARB) exhibit beneficial antidiabetic effects in patients with type 2 diabetes independent of their blood pressure-lowering effects. Some antidiabetic properties of ARB and ACE-I might by exerted by activation of peroxisome proliferator-activated receptor gamma (PPARgamma). However, it is not clear whether this action is drug specific.

MATERIALS AND METHODS

The binding affinity of telmisartan, valsartan, lisinopril, rosiglitazone and angiotensin II to PPARgamma was assessed in a cell-free assay system. PPARgamma signalling was studied in isolated skeletal muscle cells using Western blot analysis of phosphorylated protein kinase B (pAKT) and phosphorylated insulin like growth factor-1 receptor (pILGF-1R). Further, the ability of the drugs under study to stimulate the release of the adipocytokine visfatin was investigated in isolated human adipocytes, skeletal muscle cells, and umbilical vein endothelial cells (HUVEC).

RESULTS

The binding affinity to PPARgamma was highest for telmisartan with a half-maximal effective concentration of 463 nM, followed by lisinopril (2.9 microM) and valsartan (6.2 microM). In skeletal muscle cells phosphorylation of ILGF-1R was 2-fold increased after incubation with telmisartan or valsartan and 1.7-fold with lisinopril. pAKT expression was enhanced after incubation with telmisartan, valsartan and with lisinopril. The release of visfatin from adipocytes was 1.6-fold increased after treatment with lisinopril and about 2.0-fold increased with telmisartan and valsartan. Similar results were obtained in skeletal muscle cells and HUVEC.

CONCLUSIONS

Our data confirm agonism of telmisartan, valsartan and lisinopril on PPARgamma. Pharmacokinetic differences may explain different potencies of PPARgamma stimulation by drugs acting on the renin-angiotensin system in clinical settings.

Glycerolipid metabolism and signaling in health and disease

Maintenance of body temperature is achieved partly by modulating lipolysis by a network of complex regulatory mechanisms. Lipolysis is an integral part of the glycerolipid/free fatty acid (GL/FFA) cycle, which is the focus of this review, and we discuss the significance of this pathway in the regulation of many physiological processes besides thermogenesis. GL/FFA cycle is referred to as a "futile" cycle because it involves continuous formation and hydrolysis of GL with the release of heat, at the expense of ATP. However, we present evidence underscoring the "vital" cellular signaling roles of the GL/FFA cycle for many biological processes. Probably because of its importance in many cellular functions, GL/FFA cycling is under stringent control and is organized as several composite short substrate/product cycles where forward and backward reactions are catalyzed by separate enzymes. We believe that the renaissance of the GL/FFA cycle is timely, considering the emerging view that many of the neutral lipids are in fact key signaling molecules whose production is closely linked to GL/FFA cycling processes. The evidence supporting the view that alterations in GL/FFA cycling are involved in the pathogenesis of "fatal" conditions such as obesity, type 2 diabetes, and cancer is discussed. We also review the different enzymatic and transport steps that encompass the GL/FFA cycle leading to the generation of several metabolic signals possibly implicated in the regulation of biological processes ranging from energy homeostasis, insulin secretion and appetite control to aging and longevity. Finally, we present a perspective of the possible therapeutic implications of targeting this cycling.

The novel adipocytokine visfatin exerts direct cardioprotective effects

Visfatin is an adipocytokine capable of mimicking the glucose-lowering effects of insulin and activating the pro-survival kinases phosphatidylinositol-3-OH kinase (PI3K)-protein kinase B (Akt) and mitogen-activated protein kinase kinase 1 and 2 (MEK1/2)-extracellular signal-regulated kinase 1 and 2 (Erk 1/2). Experimental studies have demonstrated that the activation of these kinases confers cardioprotection through the inhibition of the mitochondrial permeability transition pore (mPTP). Whether visfatin is capable of exerting direct cardioprotective effects through these mechanisms is unknown and is the subject of the current study. Anaesthetized C57BL/6 male mice were subjected to in situ 30 min. of regional myocardial ischaemia and 120 min. of reperfusion. The administration of an intravenous bolus of visfatin (5 × 10⁻⁶μmol) at the time of myocardial reperfusion reduced the myocardial infarct size from 46.1 ± 4.1% in control hearts to 27.3 ± 4.0% (n≥ 6/group, P < 0.05), an effect that was blocked by the PI3K inhibitor, wortmannin, and the MEK1/2 inhibitor, U0126 (48.8 ± 5.5% and 45.9 ± 8.4%, respectively, versus 27.3 ± 4.0% with visfatin; n≥ 6/group, P < 0.05). In murine ventricular cardiomyocytes subjected to 30 min. of hypoxia followed by 30 min. of reoxygenation, visfatin (100 ng/ml), administered at the time of reoxygenation, reduced the cell death from 65.2 ± 4.6% in control to 49.2 ± 3.7%(n > 200 cells/group, P < 0.05), an effect that was abrogated by wortmannin and U0126 (68.1 ± 5.2% and 59.7 ± 6.2%, respectively; n > 200 cells/group, P > 0.05). Finally, the treatment of murine ventricular cardiomyocytes with visfatin (100 ng/ml) delayed the opening of the mPTP induced by oxidative stress from 81.2 ± 4 sec. in control to 120 ± 7 sec. (n > 20 cells/group, P < 0.05) in a PI3K- and MEK1/2-dependent manner. We report that the adipocytokine, visfatin, is capable of reducing myocardial injury when administered at the time of myocardial reperfusion in both the in situ murine heart and the isolated murine cardiomyocytes. The mechanism appears to involve the PI3K and MEK1/2 pathways and the mPTP.

Pioglitazone (7.5 mg/day) added to flutamide-metformin in women with androgen excess: additional increments of visfatin and high molecular weight adiponectin

BACKGROUND AND AIM

Low-dose pioglitazone (Pio), flutamide (Flu), metformin (Met) plus an oestro-progestagen is a novel polytherapy lowering total and visceral adiposity, and reducing carotid intima media thickness (IMT) in hyperinsulinaemic women with androgen excess, without changing their body mass index (BMI). In a search for mediators of PioFluMet's actions, we measured serum levels of visfatin and high molecular weight (HMW) adiponectin.

DESIGN AND PATIENTS

In a double-blind study, we enrolled 38 young women with hyperinsulinaemic androgen excess [mean BMI: 23.7 kg/m(2)], all of whom started on Flu (62.5 mg/day), Met (850 mg/day) and a transdermal oestro-progestagen, each for 21/28 days over 1 year. Patients were randomly assigned to receive, in addition, placebo (n = 19) or Pio (7.5 mg/day; n = 19) on the same 21/28 days.

MEASUREMENTS

Serum concentrations of visfatin and HMW adiponectin, visceral fat by magnetic resonance imaging, carotid IMT by ultrasound, all carried out during study start and after 1 year.

RESULTS

PioFluMet raised visfatin by a mean 84% and HMW adiponectin by 157% (P < 0.001), and reduced visceral fat and IMT by a mean 22% and 31% (both P < 0.001). Low-dose Pio accounted for about half of the PioFluMet effects on IMT, visfatin and HMW adiponectin.

CONCLUSION

In hyperinsulinaemic women with androgen excess, low-dose polytherapy with PioFluMet evoked striking rises in both circulating visfatin and HMW adiponectin, while lowering IMT and reducing visceral adiposity within 1 year.

Is PBEF/visfatin/Nampt an authentic adipokine relevant to the metabolic syndrome?

Adipokines are peptides secreted by adipose tissue that affect whole-body energy metabolism. Their dysregulated production in obesity has implicated them as important mediators in the pathogenesis of obesity-related risk factors for diabetes and cardiovascular disease. PBEF/visfatin/Nampt has recently been described as a novel adipokine with insulin mimetic properties. However, whether it is an authentic adipokine relevant to the metabolic syndrome remains a matter of some debate.

Effect of PPAR-δ agonist on the expression of visfatin, adiponectin, and resistin in rat adipose tissue and 3T3-L1 adipocytes

It has been recently reported that activation of PPAR-delta, by specific agonists or genetic manipulation, alleviates dyslipidemia, hyperglycemia, and insulin resistance in animal models of obesity and type 2 diabetes. The purpose of the present study was to determine whether the PPAR-delta agonist has a direct effect on adipokines in visceral adipose tissue of rats and in cultured adipocytes. We examined the expression of visfatin, adiponectin, and resistin mRNA in visceral adipose tissue of Wistar rats fed a high-fat diet and 3T3-L1 adipocytes treated with PPAR-delta agonist (L-165041). Body weight and biochemical measurements were performed. Rats fed a high-fat diet showed a greater increase in body weight than those fed a standard diet (P<0.05), and treatment with L-165041 (10 mg/kg/day) significantly decreased weight gain (P<0.05). The concentration of total cholesterol was lower, and HDL cholesterol was higher in L-165041-treated rats (P<0.05). In the visceral adipose tissue of L-165041-treated rats, visfatin and adiponectin mRNA levels significantly increased compared to those of the untreated rats (P<0.05). However, the expression of resistin decreased in the L-165041-treated rats. Furthermore, in cultured 3T3-L1 adipocytes, the level of visfatin and adiponectin mRNA was up-regulated in response to L-165041 treatment for nine days. By contrast, resistin mRNA levels were down-regulated by L-165041 treatment. The present study provides a novel evidence to suggest that the PPAR-delta agonist has regulatory effects on a variety of adipokines, and these effects might explain some of their metabolic function.

Effect of rosiglitazone on visfatin and retinol-binding protein-4 plasma concentrations in HIV-positive patients

Thiazolidinediones (TZD) may improve insulin resistance in patients with diabetes and HIV. The novel adipocytokines visfatin and retinol-binding protein-4 (RBP-4) have been proposed to influence the development of impaired glucose tolerance. The impact of TZD on these cytokines is yet unknown. In this randomized, double-blind, placebo-controlled parallel group study, 37 lean HIV-positive subjects aged 19-50 years were treated with 8 mg/day rosiglitazone (n=20) or placebo (n=17) for 6 months. Insulin sensitivity was estimated from the homeostasis model assessment (HOMA) index. Fasting visfatin, RBP-4, leptin, and adiponectin plasma concentrations were analyzed by immunoassays. Rosiglitazone had no effect on impaired insulin sensitivity, but increased median plasma visfatin from 6.2 ng/ml (95% CI: 5.9; 6.5) to 13.7 ng/ml (12.6; 19.1) (P<0.001) and adiponectin from 3.2 ng/ml (2.2; 4.0) to 4.0 ng/ml (3.3; 8.5; P<0.001). RBP-4 was lowered from 21.0 ng/ml (19.6; 23.1) to 16.3 ng/ml (15.2; 17.0; P<0.001), and leptin concentrations were unchanged. Adipocytokine concentrations were stable in subjects receiving placebo, where a deterioration in insulin sensitivity was detectable (P<0.05). Changes in visfatin and RBP-4 were correlated in subjects receiving rosiglitazone (r=-0.64, P<0.01) but not placebo (r=0.12, P=0.15). TZD treatment affects circulating adipocytokine concentrations in subjects with HIV. Reductions in RBP-4 and increases in visfatin may contribute to the pharmacodynamic action of TZD on glucose homeostasis. Quantification of adipocytokines might be useful to assess TZD treatment effectiveness in insulin-resistant subjects with HIV.