Visceral Adipose Tissue-derived Serine Protease Research Articles

Effects of pioglitazone/metformin fixed-dose combination therapy and metformin monotherapy on serum vaspin, adiponectin, and interleukin-6 levels in patients with type 2 diabetes

[Summary] Sixty-eight patients with type 2 diabetes were divided into 2 groups.The patients in two groups were given metformin or pioglitazone/metformin treatment respectively for 12 weeks.The level of serum interleukin-6 (IL-6),vaspin,adiponectin,blood glucose,and other indicators before and after the treatment in patients of two groups were observed.After the treatment,the level of serum IL-6 and adiponeetin changed significantly in pioglitazone/metformin group(P＜0.05,P＜0.01).The 2hPG and HbIC in metformin group were higher than that in pioglitazone/metformin group (P ＜0.01,P ＜ 0.05).The rate of BMI change was not related with the rate of adipocytokines change,so was the rate of HbAIC change.Effects of pioglitazone/metformin on blood glucose and adipocytokines were more significant than metformin alone,which did not depend on the decrease of glucose level and body weight. Key words: Diabetes mellitus, type 2 ; Pioglitazone ; Metformin ; Visceral adipose tissue-derived serine protease inhibitor; Adiponectin; Interleukin-6

Analysis of a rare functional truncating mutation rs61757459 in vaspin (SERPINA12) on circulating vaspin levels

A recent genome-wide association study suggests that genetic variation within the vaspin gene might contribute to the variability in circulating serum visceral adipose tissue-derived serine protease inhibitor (vaspin) concentrations. Here, we analyzed the functional consequences of the rare variant rs61757459 predicting a premature stop codon and its impact on circulating serum vaspin concentrations. In order to identify genetic variation, we sequenced the vaspin gene in 48 nonrelated Caucasian subjects. Rs61757459 was subsequently genotyped in three metabolically well-characterized German cohorts (N = 4,019). We addressed the impact of rs61757459 on the crystal structure of vaspin and investigated its effects on vaspin expression in vivo as well as in vitro using various cell lines (Escherichia coli, HEK293). Along with previously reported common genetic variants, sequencing of vaspin revealed a rare variant (rs61757459; minor allele frequency: 1 %) which predicts a premature stop codon p.R211X. Heterozygous carriers of this mutation had lower circulating vaspin levels when compared with noncarriers. In silico structure analysis of the truncated vaspin, which was estimated to be 24.5 kDa, suggested misfolding and potential instability due to the absence of core structural domains. Indeed, the truncated protein was detected after recombinant expression in E. coli and in lysate, but not in supernatant of HEK293 cells. We conclude that rs61757459 is a functional mutation that results in a truncated protein whose instability likely results in reduced serum vaspin levels. A rare variant (rs61757459) in vaspin coding for the stop codon p.R211X is related to lower circulating vaspin concentrations. Structure analysis suggests misfolding and instability due to the absence of core structural domains. The truncated protein is detectable after recombinant expression in E. coli and in lysate, but not in supernatant of HEK293 cells.

MRNA expression pattern and association study with growth traits of bovine vaspin gene

Visceral adipose tissue-derived serine protease inhibitor (vaspin) is an interesting novel adipocytokine with insulin-sensitizing effects. Some studies have suggested that vaspin could play an important role in the development of obesity and metabolic disorders. However, the tissue expression patterns in cattle and impact of vaspin gene variants on the growth traits has not been determined yet. Herein, we firstly investigated the tissue expression patterns of vaspin gene in new born and adult cattle. The results showed that vaspin was ubiquitously expressed in most tissues and strongly expressed in the heart, skeletal muscle and fat. Then, genetic variants within bovine vaspin gene were screened in 1235 individuals from five Chinese indigenous cattle breeds. Two novel mutations in coding region (NW_001494061: g.1124477 G>A and g.1118561 T>C) of bovine vaspin gene were identified using MspI PCR-RFLP and HhaI ACRS PCR-RFLP detection. Association analysis revealed both two mutations were significantly associated with bodyweight and chest girth at 24 months in cattle (P < 0.05). Therefore, the MspI and HhaI genetic variants of bovine vaspin gene were recommended as DNA markers related to growth traits through marker-assisted selection for genetics and breeding in cattle.

Effect of statin therapy on vaspin levels in type 2 diabetic patients

BackgroundStatins are commonly used antihyperlipidemic agents, with anti-inflammatory and immunomodulatory properties that are thought to account for a significant portion of their ability to protect against atherosclerosis and cardiovascular disease. Vaspin, a visceral adipose tissue-derived serine protease inhibitor, is an emerging adipokine with important insulin-sensitizing, cardioprotective, and antiatherosclerotic properties in patients with diabetes. In this randomized controlled clinical trial, we evaluated the effect of statin therapy on vaspin levels in patients with type 2 diabetes mellitus.MethodsPatients were divided into two groups, ie, those receiving simvastatin (study group, n = 33), and those who did not (control group, n = 29). Patient data, blood biochemistry, and vaspin levels were recorded at the beginning of the study (baseline) and after 8 weeks (end of the study).ResultsAfter 8 weeks of treatment, vaspin levels were increased in patients treated with simvastatin (504.58 ± 203.07 pg/mL at baseline versus 629.15 ± 68.39 pg/mL after 8 weeks, P < 0.01), but not in patients who were not treated with simvastatin (613.33 ± 357.53 pg/mL at baseline versus 582.37 ± 84.63 pg/mL after 8 weeks, P > 0.05). In addition, the lipid-lowering effect of simvastatin was reflected in a statistically significant reduction in total cholesterol in the study group (220.75 ± 55.66 mg/dL at baseline versus 201.90 ± 53.65 mg/dL after 8 weeks P < 0.01) but not in the control group (214.24 ± 47.2 mg/dL at baseline versus 215.72 ± 43.65 mg/dL after 8 weeks, P > 0.05) and in a statistically significant reduction in triglyceride levels in the study group (265.8 ± 210.41 mg/dL at baseline versus 223.03 ± 178.67 mg/dL after 8 weeks, P < 0.05) but not in the control group (225.44 ± 115.13 mg/dL at baseline versus 215.58 ± 110.2 mg/dL after 8 weeks, P > 0.05). Mean vaspin levels were significantly higher in the study group than in the control group.ConclusionThese results indicate that statin therapy increases plasma vaspin levels in addition to having a lipid-lowering effect. This could be a mechanism underlying the pleiotropic effects seen with statins, including their cardioprotective and antiatherosclerotic effects.

Vaspin Attenuates RANKL-Induced Osteoclast Formation in RAW264.7 Cells

Visceral adipose tissue-derived serine protease inhibitor (vaspin), an adipokine that was recently identified in a rat model of type 2 diabetes, has been suggested to have an insulin-sensitizing effect. In this study, we investigated whether vaspin inhibits receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis using two types of osteoclast precursors: RAW264.7 cells and bone marrow cells (BMCs). Vaspin inhibited RANKL-induced osteoclastogenesis in RAW264.7 cells and BMCs. Interestingly, vaspin also inhibited the RANKL-induced expression of nuclear factor of activated T cells c1 (NFATc1) in RAW264.7 cells and BMCs. Furthermore, it inhibited the RANKL-induced upregulation of matrix metalloproteinase-9 and cathepsin K in RAW264.7 cells. Thus, we suggest that vaspin downregulates osteoclastogenesis in part by inhibiting expression of the transcription factor NFATc1.

Vaspin Is an Adipokine Ameliorating ER Stress in Obesity as a Ligand for Cell-Surface GRP78/MTJ-1 Complex

It is unknown whether adipokines derived from adipose tissues modulate endoplasmic reticulum (ER) stress induced in obesity. Here, we show that visceral adipose tissue–derived serine protease inhibitor (vaspin) binds to cell-surface 78-kDa glucose-regulated protein (GRP78), which is recruited from ER to plasma membrane under ER stress. Vaspin transgenic mice were protected from diet-induced obesity, glucose intolerance, and hepatic steatosis, while vaspin-deficient mice developed glucose intolerance associated with upregulation of ER stress markers. With tandem affinity tag purification using HepG2 cells, we identified GRP78 as an interacting molecule. The complex formation of vaspin, GRP78, and murine tumor cell DnaJ-like protein 1 (MTJ-1) (DnaJ homolog, subfamily C, member 1) on plasma membrane was confirmed by cell-surface labeling with biotin and immunoprecipitation in liver tissues and H-4-II-E-C3 cells. The addition of recombinant human vaspin in the cultured H-4-II-E-C3 cells also increased the phosphorylation of Akt and AMP-activated protein kinase (AMPK) in a dose-dependent manner, and anti-GRP78 antibodies completely abrogated the vaspin-induced upregulation of pAkt and pAMPK. Vaspin is a novel ligand for cell-surface GRP78/MTJ-1 complex, and its subsequent signals exert beneficial effects on ER stress–induced metabolic dysfunctions.

Genetic variation in the vaspin gene affects circulating serum vaspin concentrations

Visceral adipose tissue-derived serine protease inhibitor (vaspin) is an adipokine potentially linking obesity, insulin resistance and type 2 diabetes. Here, we searched for genetic determinants that could explain the variability in serum vaspin concentrations. First, we conducted a genome-wide association study (GWAS) for serum vaspin in the Sorbs cohort (N=826). Subsequently, 26 single-nucleotide polymorphisms (SNPs) covering genetic variation in the vaspin locus were genotyped in the Sorbs. In addition, we measured serum vaspin concentrations in 1806 samples from Augsburg/the Cooperative Health Research in the Region of Augsburg (KORA) for replication of the association signals. Finally, we conducted association analyses of vaspin SNPs with metabolic traits in the Sorbs (N=1013), KORA (N=1813) and a further cohort from Germany (Leipzig: N=1857). Six SNPs mapping between serpinA1 and serpinA4, including the vaspin locus, on chromosome 14 reached P-values < or = 10(-8) in the GWAS in the Sorbs. The fine mapping of variants within the vaspin locus in the Sorbs and subsequent replication in the KORA sample revealed several SNPs significantly associated with serum vaspin concentrations reaching P-values of up to 10(-35). However, no significant association with type 2 diabetes or related traits was found in either cohort after the Bonferroni correction for multiple comparisons. Our data show that the variability in serum vaspin concentrations might be explained by its genetic variants.

Umbilical cord and fifth-day serum vaspin concentrations in small-, appropriate-, and large-for-gestational age neonates

Vaspin is a visceral adipose tissue-derived serine protease inhibitor that has an insulin-sensitizing effect. It is correlated with insulin resistance and glucose metabolism, and it improves glucose tolerance. The aim of this study was to determine and compare serum vaspin and insulin concentrations in small-for- gestational age (SGA), appropriate-for-gestational age (AGA), and large-for-gestational age (LGA) infants at birth and fifth postnatal day. Eighty-two neonates were divided into three groups: SGA (n=22), AGA (n=30), and LGA (n=30). Mothers' age, gestational week, mode of delivery, and maternal diseases, such as diabetes, pre-eclampsia, and eclampsia were recorded. Blood for vaspin, insulin, and glucose was collected from the cord at birth and from a peripheral vein on the fifth postnatal day. At birth, there were no statistically significant difference in serum insulin concentrations among the three groups, whereas cord serum vaspin concentrations were significantly higher in the SGA group (χ2=8.158, p<0.05). Serum glucose and vaspin levels on the fifth postnatal day had no significant difference among three groups (p<0.05). Circulating vaspin concentrations were not associated with the sex of the infant and delivery route. Cord vaspin levels are significantly higher in SGA neonates than in AGA or LGA neonates. The fetal programming hypothesis proposes that many adulthood diseases originate from the adaptation that the fetus makes when it is undernourished. High cord-vaspin levels in SGA infants may be one of the adaptations for increased risk for adult metabolic diseases.

Association of serum visceral adipose tissue-derived serine protease inhibitor levels with carotid atherosclerosis in elderly patients with type 2 diabetes

The serum levels of visceral adipose tissue-derived serine protease inhibitor (vaspin)were measured in 65 elderly type 2 diabetic patients with carotid atherosclerosis( T2DM + CA group), 63 elderly type 2 diabetic patients without carotid atherosclerosis (T2DM group ) and 55 normal elderly individuals( NC group)by enzyme-linked immunosorbent assay. The results showed that the serum vaspin levels in T2DM + CA group were significantly lower than those in T2DM group[(0. 23 ± 0. 13 ) μg/L vs.(0. 41±0. 16)μg/L, P ＜0. 01]. The serum vaspin levels in T2DM + CA group and T2DM group were significantly lower than those in NC group respectively[(0. 63 ± 0. 11 ) μg/L, P ＜ 0. 01 and P ＜ 0. 05].Logistic regression analysis showed that high sensitivety C-reactive protein and Homeostasis Model Assessment insulin resistance index (HOMA-IR) were negatively correlated with serum vaspin levels,which indicates that lower serum vaspin levels might be associated with the pathogenesis of carotid atherosclerosis in elderly type 2 diabetic patients. Key words: Diabetes mellitus; Atherosclerosis

Vaspin in newly and previously diagnosed Chinese type 2 diabetic females: a case-control study

Abstract Background: Visceral adipose tissue-derived serine protease inhibitor (vaspin) is a novel adipocytokine. Several studies have indicated that vaspin may exert an important role in the development of metabolic disorders. Objective: Evaluate serum vaspin and its relation to clinical parameters in newly and previously diagnosed Chinese type 2 diabetes mellitus (T2DM) females as a case-control study. Materials and methods: One hundred twenty female participants (newly and previously diagnosed T2DM patients) were recruited from an affiliated hospital of Harbin Medical University. Sixty healthy female volunteers from various communities were included as controls. Anthropometric parameters, serum fasting blood glucose, fasting insulin, lipid profile, HbA1c, and vaspin were measured in each participant. Results: Serum vaspin levels were significantly lower in previously diagnosed T2DM patients (0.51±0.29 ng/mL) than in newly diagnosed T2DM patients (0.62±0.28 ng/mL) and healthy controls (0.69±0.31 ng/mL). However, there was no difference in serum vaspin between newly diagnosed T2DM patients and healthy controls. In multiple linear regression analysis, serum vaspin was significantly and positively associated with HbA1c in both newly and previously diagnosed T2DM patients, negatively associated with homeostasis model assessment of insulin resistance in previously diagnosed patients, and positively correlated with age and body mass index in healthy controls. Conclusion: Serum vaspin was significantly lower in previously diagnosed T2DM patients than in newly diagnosed T2DM patients and healthy controls. Serum vaspin might be a predictor of poor glucose control and insulin resistance in T2DM.

Vaspin prevents TNF-α-induced intracellular adhesion molecule-1 via inhibiting reactive oxygen species-dependent NF-κB and PKCθ activation in cultured rat vascular smooth muscle cells

Vaspin (visceral adipose tissue-derived serine protease inhibitor) was recently identified as a novel adipocytokine with insulin-sensitizing effects. We hypothesized that vaspin could play a role in vascular inflammation. To test the hypothesis, we investigated the effects of vaspin on TNF-α-stimulated vascular smooth muscle cells (SMCs) focusing on inflammatory signal transduction. Vascular SMCs from mesenteric artery of male Wistar rats were treated with TNF-α (5–10ng/ml, 20min–6h) in the absence or presence of vaspin (1–300ng/ml, pretreatment for 24h). Western blotting was performed to analyze the cellular signal. Reactive oxygen species (ROS) generation was fluorometrically measured using 2′,7′-diclorofluorescein diacetate. Vaspin alone treatment had no effect on vascular SMCs morphology and cellular signal. Vaspin significantly decreased the TNF-α-induced monocyte adhesion to SMCs. Vaspin significantly inhibited the protein expression of intracellular adhesion molecule (ICAM)-1 and the phosphorylation of NF-κB and protein kinase C (PKC)θ induced by TNF-α. Both of NF-κB and novel PKC inhibitors significantly attenuated the TNF-α-induced ICAM-1 expression. Moreover, vaspin inhibited TNF-α-induced ROS generation. An anti-oxidant, N-acetyl-l-cysteine blocked the TNF-α-induced activation of NF-κB, PKCθ and expression of ICAM-1. The present results demonstrated for the first time that vaspin inhibits TNF-α-induced expression of ICAM-1 via preventing the ROS generation and subsequent activation of NF-κB and PKCθ. Consequently, vaspin could play inhibitory roles on inflammatory states of vascular SMCs.

Effects of short-term continuous subcutaneous insulin infusion on fasting plasma vaspin levels in patients with recent-onset type 2 diabetes mellitus

Objective To investigate the effects of short-term continuous subcutaneous insulin infusion (CSII) on plasma visceral adipose tissue-derived serine protease inhibitor ( vaspin ) levels in patients with recentonset type 2 diabetes mellitus, and to study the association between insulin sensitivity and vaspin levels.Methods Thirty patients with recent-onset type 2 diabetes mellitus were treated with CSII for 2 weeks.Euglycemic-hyperinsulinemic clamps (EHC) were performed to evaluate the insulin sensitivity in type 2 diabetes group. Plasma vaspin levels were measured by an ELISA kit. The association between plasma vaspin levels and metabolic parameters were analyzed. Results Fasting plasma vaspin levels were higher in type 2 diabetes than in impaired glucose regulation and normal glucose tolerance groups [( 1.83±0.55 vs 0. 43±0.21 and 0.56±0.26) ng/ml,P＜0.05]. With CSII,vaspin levels [( 1.19 ±0.57 vs 1.83 ±0.55 ) ng/ml, P＜0.05] and homeostasis model assessment for insulin resistance [HOMA-IR ,2.30 ( 1.09-7.2 ) vs 4.28 ( 1.7-6.47 ), P＜0.05] were significantly decreased,accompanied with an increase in glucose metabolic rate [(5. 10±0.51 vs 2.99±0.42 )mg·kg-1·min-1 ,P＜0.05] in type 2 diabetes group. Changes in circulating vaspin concentrations were correlated positively with changes in HOMA-IR. Conclusion In type 2 diabetic patients,elevated plasma vaspin levels are significantly decreased after CSII treatment. Vaspin may play a role in improving insulin sensitivity of diabetic humans. Key words: Serine protease inhibitor; Diabetes mellitus, type 2; Continuous subcutaneous insulin infusion; Euglycemic-hyperinsulinemic clamp

Vaspin is related to gender, puberty and deteriorating insulin sensitivity in children

Visceral adipose tissue-derived serine protease inhibitor (vaspin) has been suggested as a novel adipocytokine related to obesity and insulin sensitivity in adults. We quantified vaspin serum concentrations in 65 lean and 67 obese children and aimed to evaluate the relationship of vaspin with physical development, obesity, and metabolic and cardiovascular phenotypes in children. We further assessed the acute vaspin response to glucose provocation in 20 obese adolescents and evaluated tissue expression patterns of vaspin in humans. Vaspin levels were significantly higher in girls than in boys. In girls, vaspin increased with age and pubertal stage, whereas there was no change with development in boys. Obese girls had lower vaspin serum levels than those of lean controls, but there was no significant correlation with body mass index (BMI). Independent of sex, age and BMI, lower vaspin was associated with better insulin sensitivity, with higher systolic blood pressure and impaired endothelial function. In response to glucose provocation during an oral glucose tolerance test, vaspin serum levels declined by approximately 25% in adolescents with hyperinsulinemia, whereas there was no significant decline in normoinsulinemic patients. In support of our clinical data, we not only confirmed vaspin mRNA expression in adipose tissue but also found consistent expression of vaspin in the liver and indications for expression in the pancreas and the skin. We showed that gender differences in circulating vaspin levels develop during pubertal progression in girls. Although vaspin's association with obesity remains controversial, vaspin was increased with worsening insulin resistance already in children and was acutely down-regulated following glucose provocation in insulin-resistant adolescents independent of obesity. Besides adipose tissue, vaspin expression in the liver and the pancreas may potentially contribute to circulating vaspin levels and their regulation.

Circadian Rhythm of Serum Vaspin in Healthy Male Volunteers: Relation to Meals

Visceral adipose tissue-derived serine protease inhibitor (vaspin) is a novel adipokine with insulin-sensitizing effects. However, the physiological role for vaspin in human metabolic regulation remains to be established. We studied the 24-h profiles of circulating vaspin concentrations in relation to meal ingestion in normal adults. Blood samples were drawn 39 times throughout a 24-h period from 10 healthy male subjects provided with meals on a fixed schedule. On a separate day, four subjects were fasted and then provided with an unexpected meal to clarify the effect of meal consumption on serum vaspin levels. Serum vaspin concentrations were determined by ELISA. Serum vaspin levels were highest in the early morning before breakfast and fell to trough levels within 2 h after breakfast. Serum vaspin levels also showed a preprandial rise and postprandial fall at lunch and dinner, although at lesser degrees than at breakfast. Intermeal vaspin concentrations reached a nadir in the mid-afternoon and showed a nocturnal rise, with peak nighttime vaspin levels being approximately 250% of nadir levels. Unscheduled food ingestion after a prolonged fast significantly reduced serum vaspin levels, suggesting that energy intake itself has a suppressive effect on serum vaspin levels. The diurnal pattern of serum vaspin concentrations was exactly reciprocal to that of insulin and of glucose. Serum vaspin levels have a meal-related diurnal variation, suggesting a role for vaspin in metabolic regulation. However, the reciprocal relationship between serum vaspin and insulin may negate the importance of vaspin as an physiological insulin sensitizer.

Regulation of visceral adipose tissue‐derived serine protease inhibitor by nutritional status, metformin, gender and pituitary factors in rat white adipose tissue

Visceral adipose tissue-derived serine protease inhibitor (vaspin) is a recently discovered adipocytokine mainly secreted from visceral adipose tissue, which plays a main role in insulin sensitivity. In this study, we have investigated the regulation of vaspin gene expression in rat white adipose tissue (WAT) in different physiological (nutritional status, pregnancy, age and gender) and pathophysiological (gonadectomy, thyroid status and growth hormone deficiency) settings known to be associated with energy homeostasis and alterations in insulin sensitivity. We have determined vaspin gene expression by real-time PCR. Vaspin was decreased after fasting and its levels were partially recovered after leptin treatment. Chronic treatment with metformin increased vaspin gene expression. Vaspin mRNA expression reached the highest peak at 45 days in both sexes after birth and its expression was higher in females than males, but its levels did not change throughout pregnancy. Finally, decreased levels of growth hormone and thyroid hormones suppressed vaspin expression. These findings suggest that WAT vaspin mRNA expression is regulated by nutritional status, and leptin seems to be the nutrient signal responsible for those changes. Vaspin is influenced by age and gender, and its expression is increased after treatment with insulin sensitizers. Finally, alterations in pituitary functions modify vaspin levels. Understanding the molecular mechanisms regulating vaspin will provide new insights into the pathogenesis of the metabolic syndrome.

Vaspin Can Not Inhibit TNF-.ALPHA.-Induced Inflammation of Human Umbilical Vein Endothelial Cells

Visceral adipose tissue-derived serine protease inhibitor (vaspin) has been recently identified as an adipocytokine in a rat model of type 2 diabetes. Adipocytokines may directly influence the function of endothelial cells (ECs) and modulate inflammatory states. We therefore assessed the effects of vaspin on basal and TNF-alpha-stimulated human umbilical vein ECs. Vaspin (10-100 ng/ml, 24 hr) had no effects on both basal ECs morphology and TNF-alpha-induced (10 ng/ml, 24 hr) morphological damages. Vaspin did not inhibit the TNF-alpha (20 min) activation of JNK, p38 and NF-kappaB, but only slightly inhibited Akt. Furthermore, vaspin did not decrease the TNF-alpha (24 hr) induction of vascular cell adhesion molecule-1, intercellular adhesion molecule-1, endothelial selectin, and cyclooxygenase-2 protein expression as well as monocyte chemotactic protein-1, tissue factor, and plasmogen activator inhibitor-1 mRNA expression. The present results indicate that vaspin has no effects on normal ECs, and can not prevent TNF-alpha-induced inflammatory injury.

Serum Visceral Adipose Tissue–Derived Serine Protease Inhibitor Concentrations in Human Obesity and Polycystic Ovary Syndrome

Adipokines, such as the insulin-sensitizing adipokine visceral adipose tissue–derived serine protease inhibitor (vaspin), play an important role in the interaction among androgen excess, abdominal adiposity, and insulin resistance in polycystic ovary syndrome (PCOS) (1). A recently published small case-control study suggests that PCOS patients have increased vaspin mRNA and protein in omental adipose tissue and increased circulating vaspin concentrations that decrease after treatment with the insulin-sensitizer drug metformin (2). We measured vaspin levels in serum samples from 42 PCOS patients and 42 nonhyperandrogenic women matched for age, BMI, and frequency of obesity (48%, as defined by a BMI ≥30 kg/m2) in samples from 26 severely obese premenopausal women (15 had PCOS) obtained before and after bariatric surgery and in samples from 34 different PCOS …

A Novel Adipocytokine, Visceral Adipose Tissue-derived Serine Protease Inhibitor (Vaspin), and Obesity

Visceral adipose tissue-derived serine protease inhibitor (vaspin) is an interesting novel adipocytokine with insulin-sensitizing effects. Some studies have suggested that vaspin could play an important role in the development of obesity and metabolic disorders. The induction of vaspin mRNA expression could represent a compensatory mechanism associated with obesity, severe insulin resistance and type 2 diabetes mellitus, however it is unclear whether a correlation exists between human vaspin serum levels and markers of insulin sensitivity and glucose or lipid metabolism. Vaspin serum concentrations have been shown to be lower in lean subjects and competitive sportsmen with long-term physical training, but they are increased with weight loss associated with a physical training programme. In conclusion, there is at present no clear proof of a causal link between vaspin and visceral fat accumulation, or insulin resistance. This article reviews the role of vaspin in obesity-associated diseases and its potential as a new biomarker for obesity and impaired insulin sensitivity.

Metformin Decreases the Adipokine Vaspin in Overweight Women With Polycystic Ovary Syndrome Concomitant With Improvement in Insulin Sensitivity and a Decrease in Insulin Resistance

Polycystic ovary syndrome (PCOS) is associated with insulin resistance and obesity. Vaspin (visceral adipose tissue-derived serine protease inhibitor) levels increase with hyperinsulinemia and obesity. Currently, no data exists on vaspin in PCOS women. We therefore assessed mRNA and protein levels of vaspin, including circulating vaspin, from subcutaneous and omental adipose tissue of PCOS women and matched control subjects. Ex vivo regulation of adipose tissue vaspin and the effects of metformin treatment on circulating vaspin levels in PCOS subjects were also studied. Real-time RT-PCR and Western blotting were used to assess mRNA and protein expression of vaspin. Serum vaspin was quantified by enzyme-linked immunosorbent assay. The effects of d-glucose, insulin, and gonadal and adrenal steroids on adipose tissue vaspin were analyzed ex vivo. There were significantly higher levels of circulating vaspin (P < 0.05), vaspin mRNA (P < 0.05), and protein (P < 0.05) in omental adipose tissue of PCOS women. Interestingly, in omental adipose tissue explants, glucose significantly increased vaspin protein levels and secretion into conditioned media (P < 0.001). Also, after 6 months of metformin treatment, there was a significant decrease in serum vaspin levels in PCOS women (P < 0.001). Furthermore, multivariate regression analysis revealed that following metformin therapy, changes in circulating glucose levels were predictive of changes in serum vaspin levels (P = 0.014). We report, for the first time, elevated serum and omental adipose tissue levels of vaspin in overweight PCOS women and ex vivo regulation of vaspin, predominantly by glucose. More importantly, metformin treatment decreases serum vaspin levels, a novel observation.

Secretome of Primary Cultures of Human Adipose-derived Stem Cells: Modulation of Serpins by Adipogenesis

Studies of adipogenic protein induction have led to a new appreciation of the role of adipose tissue as an endocrine organ. Adipocyte-derived "adipokines" such as adiponectin, leptin, and visceral adipose tissue-derived serine protease inhibitor (vaspin) exert hormone-like activities at the systemic level. In this study, we examined the secretome of primary cultures of human subcutaneous adipose-derived stem cells as an in vitro model of adipogenesis. Conditioned media obtained from four individual female donors after culture in uninduced or adipogenic induced conditions were compared by two-dimensional gel electrophoresis and tandem mass spectrometry. Over 80 individual protein features showing > or =2-fold relative differences were examined. Approximately 50% of the identified proteins have been described previously in the secretome of murine 3T3-L1 preadipocytes or in the interstitial fluid derived from human mammary gland adipose tissue. As reported by others, we found that the secretome included proteins such as actin and lactate dehydrogenase that do not display a leader sequence or transmembrane domain and are classified as "cytoplasmic" in origin. Moreover we detected a number of established adipokines such as adiponectin and plasminogen activator inhibitor 1. Of particular interest was the presence of multiple serine protease inhibitors (serpins). In addition to plasminogen activator inhibitor 1, these included pigment epithelium-derived factor (confirmed by Western immunoblot), placental thrombin inhibitor, pregnancy zone protein, and protease C1 inhibitor. These findings, together with the recent identification of vaspin, suggest that the serpin protein family warrants further proteomics investigation with respect to the etiology of obesity and type 2 diabetes.