Visceral adipose tissue-derived serine proteinase inhibitor inhibits apoptosis of endothelial cells as a ligand for the cell-surface GRP78/voltage-dependent anion channel complex

GRP78 Contributes to the Beneficial Effects of SGLT2 Inhibitor on Proximal Tubular Cells in DKD

The beneficial effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors on kidney function are well-known; however, their molecular mechanisms are not fully understood. We focused on 78-kDa glucose-regulated protein (GRP78) and its interaction with SGLT2 and integrin-β1 beyond the chaperone property of GRP78. In streptozotocin (STZ)-induced diabetic mouse kidneys, GRP78, SGLT2, and integrin-β1 increased in the plasma membrane fraction, while they were suppressed by canagliflozin. The altered subcellular localization of GRP78/integrin-β1 in STZ mice promoted epithelial mesenchymal transition (EMT) and fibrosis, which were mitigated by canagliflozin. High-glucose conditions reduced intracellular GRP78, increased its secretion, and caused EMT-like changes in cultured HK2 cells, which were again inhibited by canagliflozin. Urinary GRP78 increased in STZ mice, and in vitro experiments with recombinant GRP78 suggested that inflammation spread to surrounding tubular cells and that canagliflozin reversed this effect. Under normal glucose culture, canagliflozin maintained sarco/endoplasmic reticulum (ER) Ca2+-ATPase (SERCA) activity, promoted ER robustness, reduced ER stress response impairment, and protected proximal tubular cells. In conclusion, canagliflozin restored subcellular localization of GRP78, SGLT2, and integrin-β1 and inhibited EMT and fibrosis in DKD. In nondiabetic chronic kidney disease, canagliflozin promoted ER robustness by maintaining SERCA activity and preventing ER stress response failure, and it contributed to tubular protection.

ARTICLE HIGHLIGHTS

LRP1 is the cell-surface endocytosis receptor for vaspin in adipocytes

Vaspin is a serine protease inhibitor that protects against adipose tissue inflammation and insulin resistance, two key drivers of adipocyte dysfunction and metabolic disorders in obesity. Inhibition of target proteases such as KLK7 has been shown to reduce adipose tissue inflammation in obesity, while vaspin binding to cell surface GRP78 has been linked to reduced obesity-induced ER stress and insulin resistance in the liver. However, the molecular mechanisms by which vaspin directly affects cellular processes in adipocytes remain unknown. Using fluorescently labeled vaspin, we found that vaspin is rapidly internalized by mouse and human adipocytes, but less efficiently by endothelial, kidney, liver, and neuronal cells. Internalization occurs by active, clathrin-mediated endocytosis, which is dependent on vaspin binding to the LRP1 receptor, rather than GRP78 as previously thought. This was demonstrated by competition experiments and RNAi-mediated knock-down in adipocytes and by rescuing vaspin internalization in LRP1-deficient Pea13 cells after transfection with a functional LRP1 minireceptor. Vaspin internalization is further increased in mature adipocytes after insulin-stimulated translocation of LRP1. Although vaspin has nanomolar affinity for LRP1 clusters II-IV, binding to cell surface heparan sulfates is required for efficient LRP1-mediated internalization. Native, but not cleaved vaspin, and also vaspin polymers are efficiently endocytosed, and ultimately targeted for lysosomal degradation. Our study provides mechanistic insight into the uptake and degradation of vaspin in adipocytes, thereby broadening our understanding of its functional repertoire. We hypothesize the vaspin-LRP1 axis to be an important mediator of vaspin effects not only in adipose tissue but also in other LRP1-expressing cells.

Adipokine vaspin maintains angiogenesis and neurological function during cerebral ischemia-reperfusion via suppressing endoplasmic reticulum stress

INTRODUCTION

Visceral adipose tissue-derived serine protease inhibitor (vaspin) is an adipokine. It has been reported that decreased serum vaspin levels are significantly associated with stroke severity and prognosis.

PURPOSE

This article aims to explore the theoretical feasibility of vaspin supplementation for cerebral ischemia-reperfusion (I/R) injury.

METHODS

The I/R mouse models were constructed by the middle cerebral artery occlusion (MCAO) method, and the effects of vaspin on cerebral infarction, neurological function, angiogenesis and endoplasmic reticulum (ER) stress were explored. To verify the mediation of ER stress in the regulation of vaspin, human brain microvascular endothelial cells (HBMECs) were subjected to ER stress agonist tunicamycin in vitro. The impacts of vaspin and tunicamycin on oxygen glucose deprivation/ recovery (OGD/R)-induced cell viability, apoptosis, and angiogenesis were examined.

RESULTS

Vaspin inhibited blood-brain barrier breakdown and infarction occurred in the brain tissue of the I/R mice. Vaspin also enhanced cerebral neovascularization and reduced the apoptosis. Additional tunicamycin increased the apoptosis of HBMECs and inhibited angiogenesis, reversing the protective effect of vaspin on cells.

CONCLUSION

Together, this study reveals that vaspin supplementation reduces cerebral infarction and works against neurological dysfunction. It maintains the survival and angiogenesis capacity of HBMECs by inhibiting ER stress.

Proteomics associated with coronary high-risk plaques by optical coherence tomography

Biomarkers are widely used for the diagnosis and monitoring of cardiovascular disease. However, markers for coronary high-risk plaques have not been identified. The aim of this study was to identify proteins specific to coronary high-risk plaques. Fifty-one patients (71.2 ± 11.1 years, male: 66.7%) who underwent intracoronary optical coherence tomography imaging and provided blood specimens for proteomic analysis were prospectively enrolled. A total of 1470 plasma proteins were analyzed per patient using the Olink® Explore 1536 Reagent Kit. In patients with thin-cap fibroatheroma, the protein expression of Calretinin (CALB2), Corticoliberin (CRH) and Alkaline phosphatase, placental type (ALPP) were significantly increased, while the expression of Neuroplastin (NPTN), Folate receptor gamma (FOLR3) and Serpin A12 (SERPINA12) were significantly decreased. In patients with macrophage infiltration, the protein expressions of Fatty acid-binding protein, intestinal (FABP2), and Fibroblast growth factor 21 (FGF21) were significantly decreased. In patients with lipid-rich plaques, the protein expression of Interleukin-17 C (IL17C) was significantly increased, while the expression of Fc receptor-like protein 3 (FCRL3) was significantly decreased. These proteins might be useful markers in identifying patients with coronary high-risk plaques. Clinical Trial Registration: https://www.umin.ac.jp/ctr/ , UMIN000041692.

SERPINA12 promotes the tumorigenic capacity of HCC stem cells through hyperactivation of AKT/β-catenin signaling

BACKGROUND AND AIMS

HCC is an aggressive disease with poor clinical outcome. Understanding the mechanisms that drive cancer stemness, which we now know is the root cause of therapy failure and tumor recurrence, is fundamental for designing improved therapeutic strategies. This study aims to identify molecular players specific to CD133 + HCC to better design drugs that can precisely interfere with cancer stem cells but not normal stem cell function.

APPROACH AND RESULTS

Transcriptome profiling comparison of epithelial-specific "normal" CD133 + cells isolated from fetal and regenerating liver against "HCC" CD133 + cells isolated from proto-oncogene-driven and inflammation-associated HCC revealed preferential overexpression of SERPINA12 in HCC but not fetal and regenerating liver CD133 + cells. SERPINA12 upregulation in HCC is tightly associated with aggressive clinical and stemness features, including survival, tumor stage, cirrhosis, and stemness signatures. Enrichment of SERPINA12 in HCC is mediated by promoter binding of the well-recognized β-catenin effector TCF7L2 to drive SERPINA12 transcriptional activity. Functional characterization identified a unique and novel role of endogenous SERPINA12 in promoting self-renewal, therapy resistance, and metastatic abilities. Mechanistically, SERPINA12 functioned through binding to GRP78, resulting in a hyperactivated AKT/GSK3β/β-catenin signaling cascade, forming a positive feed-forward loop. Intravenous administration of rAAV8-shSERPINA12 sensitized HCC cells to sorafenib and impeded the cancer stem cell subset in an immunocompetent HCC mouse model.

CONCLUSIONS

Collectively, our findings revealed that SERPINA12 is preferentially overexpressed in epithelial HCC CD133 + cells and is a key contributor to HCC initiation and progression by driving an AKT/β-catenin feed-forward loop.

Genetic dissection of serum vaspin highlights its causal role in lipid metabolism

OBJECTIVE

Vaspin (visceral adipose tissue derived serine protease inhibitor, SERPINA12) is associated with obesity-related metabolic traits, but its causative role is still elusive. The role of genetics in serum vaspin variability to establish its causal relationship with metabolically relevant traits was investigated.

METHODS

A meta-analysis of genome-wide association studies for serum vaspin from six independent cohorts (N = 7446) was conducted. Potential functional variants of vaspin were included in Mendelian randomization (MR) analyses to assess possible causal pathways between vaspin and homeostasis model assessment and lipid traits. To further validate the MR analyses, data from Genotype-Tissue Expression (GTEx) were analyzed, db/db mice were treated with vaspin, and serum lipids were measured.

RESULTS

A total of 468 genetic variants represented by five independent variants (rs7141073, rs1956709, rs4905216, rs61978267, rs73338689) within the vaspin locus were associated with serum vaspin (all p < 5×10-8 , explained variance 16.8%). MR analyses revealed causal relationships between serum vaspin and triglycerides, low-density lipoprotein, and total cholesterol. Gene expression correlation analyses suggested that genes, highly correlated with vaspin expression in adipose tissue, are enriched in lipid metabolic processes. Finally, in vivo vaspin treatment reduced serum triglycerides in obese db/db mice.

CONCLUSIONS

The data show that serum vaspin is strongly determined by genetic variants within vaspin, which further highlight vaspin's causal role in lipid metabolism.

Overexpressing high levels of human vaspin limits high fat diet-induced obesity and enhances energy expenditure in a transgenic mouse

Adipose tissue inflammation and insulin resistance are hallmarks in the development of metabolic diseases resulting from overweight and obesity, such as type 2 diabetes and non-alcoholic fatty liver disease. In obesity, adipocytes predominantly secrete proinflammatory adipokines that further promote adipose tissue dysfunction with negative effects on local and systemic insulin sensitivity. Expression of the serpin vaspin (SERPINA12) is also increased in obesity and type 2 diabetes, but exhibits compensatory roles in inflammation and insulin resistance. This has in part been demonstrated using vaspin-transgenic mice. We here report a new mouse line (h-vaspinTG) with transgenic expression of human vaspin in adipose tissue that reaches vaspin concentrations three orders of magnitude higher than wild type controls (>200 ng/ml). Phenotyping under chow and high-fat diet conditions included glucose-tolerance tests, measurements of energy expenditure and circulating parameters, adipose tissue and liver histology. Also, ex vivo glucose uptake in isolated adipocytes and skeletal muscle was analyzed in h-vaspinTG and littermate controls. The results confirmed previous findings, revealing a strong reduction in diet-induced weight gain, fat mass, hyperinsulinemia, -glycemia and -cholesterolemia as well as fatty liver. Insulin sensitivity in adipose tissue and muscle was not altered. The h-vaspinTG mice showed increased energy expenditure under high fat diet conditions, that may explain reduced weight gain and overall metabolic improvements. In conclusion, this novel human vaspin-transgenic mouse line will be a valuable research tool to delineate whole-body, tissue- and cell-specific effects of vaspin in health and disease.

Cell surface GRP78 regulates TGFβ1-mediated profibrotic responses via TSP1 in diabetic kidney disease

Introduction: Diabetic kidney disease (DKD) is the leading cause of kidney failure in North America, characterized by glomerular accumulation of extracellular matrix (ECM) proteins. High glucose (HG) induction of glomerular mesangial cell (MC) profibrotic responses plays a central role in its pathogenesis. We previously showed that the endoplasmic reticulum resident GRP78 translocates to the cell surface in response to HG, where it mediates Akt activation and downstream profibrotic responses in MC. Transforming growth factor β1 (TGFβ1) is recognized as a central mediator of HG-induced profibrotic responses, but whether its activation is regulated by cell surface GRP78 (csGRP78) is unknown. TGFβ1 is stored in the ECM in a latent form, requiring release for biological activity. The matrix glycoprotein thrombospondin 1 (TSP1), known to be increased in DKD and by HG in MC, is an important factor in TGFβ1 activation. Here we determined whether csGRP78 regulates TSP1 expression and thereby TGFβ1 activation by HG. Methods: Primary mouse MC were used. TSP1 and TGFβ1 were assessed using standard molecular biology techniques. Inhibitors of csGRP78 were: 1) vaspin, 2) the C-terminal targeting antibody C38, 3) siRNA downregulation of its transport co-chaperone MTJ-1 to prevent GRP78 translocation to the cell surface, and 4) prevention of csGRP78 activation by its ligand, active α2-macroglobulin (α2M*), with the neutralizing antibody Fα2M or an inhibitory peptide. Results: TSP1 transcript and promoter activity were increased by HG, as were cellular and ECM TSP1, and these required PI3K/Akt activity. Inhibition of csGRP78 prevented HG-induced TSP1 upregulation and deposition into the ECM. The HG-induced increase in active TGFβ1 in the medium was also inhibited, which was associated with reduced intracellular Smad3 activation and signaling. Overexpression of csGRP78 increased TSP-1, and this was further augmented in HG. Discussion: These data support an important role for csGRP78 in regulating HG-induced TSP1 transcriptional induction via PI3K/Akt signaling. Functionally, this enables TGFβ1 activation in response to HG, with consequent increase in ECM proteins. Means of inhibiting csGRP78 signaling represent a novel approach to preventing fibrosis in DKD.

Vaspin Attenuates Atrial Abnormalities by Promoting ULK1/FUNDC1-Mediated Mitophagy

The worldwide incidence and prevalence of atrial fibrillation (AF) are increasing, making it a life-threatening condition due to the higher numbers of people suffering from obesity. Vaspin, an adipokine derived from epicardial adipose tissue, has been reported to reduce inflammation, inhibit apoptosis, and induce autophagy; however, its role in the pathogenesis of AF is not known. In this study, we investigated the role of vaspin in patients with AF and explored the molecular mechanisms using atrial myocytes in vitro. Our data showed that vaspin levels were significantly reduced in the plasma of patients with AF. Lower plasma levels of vaspin were also associated with a higher risk of AF in patients with obesity. Vaspin treatment in vitro alleviated cardiomyocyte injury, atrial fibrosis, atrial myocyte apoptosis, and mitochondrial injury in atrial myocytes following Ang-II stress. Moreover, our results demonstrated that vaspin protected against Ang-II-induced atrial myocyte dysfunction by inducing mitophagy. We also observed that vaspin treatment enhanced the phosphorylation of Fun14 domain-containing protein 1 (FUNDC1) at Ser17 by unc-51 like autophagy activating kinase 1 (ULK1), resulting in the induction of mitophagy. These positive effects of vaspin were reversed by ULK1 silencing in Ang-II-stimulated HL-1 cells. Our study is the first to propose that vaspin plays a vital role in AF pathogenesis via ULK1/FUNDC1-regulated mitophagy and could be a novel therapeutic target for AF.

Serum vaspin as a predictor of severity and prognosis in acute ischemic stroke patients

Objective: The influence of vaspin on vascular health had been investigated, yielding conflicting results. This study is intended to investigate the relation between vaspin and stroke severity and stroke outcome in a cohort Chinese patient with acute ischemic stroke (AIS).Methods: This was a prospective single-center observational study in Xinxiang, China. From 1 July 2017 to 30 November 2019, all patients with first-ever AIS were consecutively included. Serum levels of vaspin, stroke severity at (assessed by NIHSS score) admission and functional outcome (assessed by modified Rankin Scale (mRS)) at discharge were recorded. Multivariate analyses were assessed using logistic regression models.Results: Finally, 340 patients with AIS were included. The median age of those patients was 65 (interquartile range [IQR], 56-74) years and 61.8% were men. At admission, 88 patients (25.9%) experienced severe stroke (NIHSS>10) and serum levels of vaspin (median [IQR]: 0.72[0.48-0.90]ng/ml) in those patients were significantly lower than in those mild(0.92[0.70-1.19]ng/ml) and moderate stroke (0.93[0.63-1.21]ng/ml). At discharge, 113 patients (33.2%) experienced poor functional outcome (mRS >2) and vaspin serum levels in those patients were lower as compared with patients who experienced good outcome (0.71[0.45-0.98] vs. 0.91[0.71-1.19]ng/ml). In multivariate analyses, lower level of vaspin (< median) was associated with a 2.5-fold (odds ratio [OR] 2.46; 95% confidence interval [CI]: 1.75-4.45) increased risk for severe stroke and a 2.1-fold (2.03; 1.42-3.58) increased risk for poor outcome.Conclusion: In conclusion, reduced serum levels of vaspin at admission are significantly related to stroke severity and prognosis, which illustrates a predictive role of reduced vaspin in ischemic stroke.

Vaspin attenuates steatosis-induced fibrosis via GRP78 receptor by targeting AMPK signaling pathway

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease that is rapidly becoming a public health problem. An imbalance in lipid distribution to the hepatocytes and metabolism causes hepatocyte steatosis. Vaspin is a newly discovered adipokine that has been linked to a variety of metabolic disorders. The effects of vaspin on steatosis and fibrosis pathogenesis and related mechanisms are unclear. Thus, this study investigated the molecular mechanism of vaspin on hepatocyte steatosis and fibrosis. HepG2 cells were treated with 1.2 mM free fatty acid and the intracellular lipid values were measured by flow cytometry and Nile red assay. RT-qPCR was used to assess the effect of vaspin and blocking of the GRP78 receptor on the expression of lipogenesis, oxidation, uptake, and secretion of fatty acid (FA), as well as AMPK activity. In co-cultured HepG2 and LX-2 cell lines, the expression of main proteins of hepatocyte fibrosis was analyzed using Western blot analysis. In the HepG2 cell line, we discovered that vaspin increased oxidation, FA secretion and gene expression, and AMPK activity and decreased lipogenesis and FA uptake and gene expression. Western blot analysis in co-cultured HepG2 and LX-2 cell lines showed that α-SMA and TGF-β1 protein expression decreased. The data demonstrated that vaspin acts as a novel regulator of hepatocyte steatosis through the GRP78 receptor, effectively reducing hepatocyte fibrosis through AMPK activation and decreasing NF-κB gene expression.

The Role of Anti-Inflammatory Adipokines in Cardiometabolic Disorders: Moving beyond Adiponectin

The global burden of obesity has multiplied owing to its rapidly growing prevalence and obesity-related morbidity and mortality. In addition to the classic role of depositing extra energy, adipose tissue actively interferes with the metabolic balance by means of secreting bioactive compounds called adipokines. While most adipokines give rise to inflammatory conditions, the others with anti-inflammatory properties have been the novel focus of attention for the amelioration of cardiometabolic complications. This review compiles the current evidence on the roles of anti-inflammatory adipokines, namely, adiponectin, vaspin, the C1q/TNF-related protein (CTRP) family, secreted frizzled-related protein 5 (SFRP5), and omentin-1 on cardiometabolic health. Further investigations on the mechanism of action and prospective human trials may pave the way to their clinical application as innovative biomarkers and therapeutic targets for cardiovascular and metabolic disorders.

Hepatokine Pregnancy Zone Protein Governs the Diet-Induced Thermogenesis Through Activating Brown Adipose Tissue

Intermittent fasting (IF), as a dietary intervention for weight loss, takes effects primarily through increasing energy expenditure. However, whether inter-organ systems play a key role in IF remains unclear. Here, a novel hepatokine, pregnancy zone protein (PZP) is identified, which has significant induction during the refeeding stage of IF. Further, loss of function studies and protein therapeutic experiment in mice revealed that PZP promotes diet-induced thermogenesis through activating brown adipose tissue (BAT). Mechanistically, circulating PZP can bind to cell surface glucose-regulated protein of 78 kDa (GRP78) to promote uncoupling protein 1 (UCP1) expression via a p38 MAPK-ATF2 signaling pathway in BAT. These studies illuminate a systemic regulation in which the IF promotes BAT thermogenesis through the endocrinal system and provide a novel potential target for treating obesity and related disorders.

Role of vaspin in porcine ovary: effect on signaling pathways and steroid synthesis via GRP78 receptor and protein kinase A†

Vaspin, visceral-adipose-tissue-derived serine protease inhibitor, is involved in the development of obesity, insulin resistance, inflammation, and energy metabolism. Our previous study showed vaspin expression and its regulation in the ovary; however, the role of this adipokine in ovarian cells has never been studied. Here, we studied the in vitro effect of vaspin on various kinase-signaling pathways: mitogen-activated kinase (MAP3/1), serine/threonine kinase (AKT), signal transducer and activator of transcription 3 (STAT3) protein kinase AMP (PRKAA1), protein kinase A (PKA), and on expression of nuclear factor kappa B (NFKB2) as well as on steroid synthesis by porcine ovarian cells. By using western blot, we found that vaspin (1 ng/ml), in a time-dependent manner, increased phosphorylation of MAP3/1, AKT, STAT3, PRKAA1, and PKA, while it decreased the expression of NFKB2. We observed that vaspin, in a dose-dependent manner, increased the basal steroid hormone secretion (progesterone and estradiol), mRNA and protein expression of steroid enzymes using real-time PCR and western blot, respectively, and the mRNA of gonadotropins (FSHR, LHCGR) and steroids (PGR, ESR2) receptors. The stimulatory effect of vaspin on basal steroidogenesis was reversed when ovarian cells were cultured in the presence of a PKA pharmacological inhibitor (KT5720) and when GRP78 receptor was knocked down (siRNA). However, in the presence of insulin-like growth factor type 1 and gonadotropins, vaspin reduced steroidogenesis. Thus, vaspin, by activation of various signaling pathways and stimulation of basal steroid production via GRP78 receptor and PKA, could be a new regulator of porcine ovarian function.

A Vaspin-HSPA1L complex protects proximal tubular cells from organelle stress in diabetic kidney disease

Proximal tubular cells (PTCs) are crucial for maintaining renal homeostasis, and tubular injuries contribute to progression of diabetic kidney disease (DKD). However, the roles of visceral adipose tissue-derived serine protease inhibitor (vaspin) in the development of DKD is not known. We found vaspin maintains PTCs through ameliorating ER stress, autophagy impairment, and lysosome dysfunction in DKD. Vaspin-/- obese mice showed enlarged and leaky lysosomes in PTCs associated with increased apoptosis, and these abnormalities were also observed in the patients with DKD. During internalization into PTCs, vaspin formed a complex with heat shock protein family A (Hsp70) member 1 like (HSPA1L) as well as 78 kDa glucose-regulated protein (GRP78). Both vaspin-partners bind to clathrin heavy chain and involve in the endocytosis. Notably, albumin-overload enhanced extracellular release of HSPA1L and overexpression of HSPA1L dissolved organelle stresses, especially autophagy impairment. Thus, vapsin/HSPA1L-mediated pathways play critical roles in maintaining organellar function of PTCs in DKD.

Adipokines in vascular calcification

Adipose tissue (AT), a critical endocrine gland, is capable of producing and secreting abundant adipokines. Adipokines act on distant or adjacent organ tissues via paracrine, autocrine, and endocrine mechanism, which play attractive roles in the regulation of glycolipid metabolism and inflammatory response. Increasing evidence shows that adipokines can connect obesity with cardiovascular diseases by serving as promoters or inhibitors in vascular calcification. The chronic hypoxia in AT, caused by the adipocyte hypertrophy, is able to trigger imbalanced adipokine generation, which leads to apoptosis, osteogenic differentiation of vascular smooth muscle cells (VSMCs), vascular inflammation, and abnormal deposition of calcium and phosphorus in the vessel wall. The objectives of this review aim at providing a brief summary of the crucial influence of major adipokines on the formation and development of vascular calcification, which may contribute to better understanding these adipokines for establishing the appropriate therapeutic strategies to counteract obesity-associated vascular calcification.

Expression and Impact of Vaspin on In Vitro Oocyte Maturation through MAP3/1 and PRKAA1 Signalling Pathways

Oocyte maturation is a critical stage in embryo production and female reproduction. The aims of this study were to determine: (i) the mRNA and protein expression of vaspin and its receptor 78-kDa glucose-regulated (GRP78) in porcine cumulus-oocyte complexes (COCs) by real-time PCR and Western blot analysis, respectively, and their localisation by immunofluorescence; and (ii) the effects of vaspin on in vitro oocyte maturation (IVM) and the involvement of mitogen ERK1/2 (MAP3/1)- and AMPKα (PRKAA1)-activated kinases in the studied processes. Porcine COCs were matured in vitro for 22 h or 44 h with vaspin at a dose of 1 ng/mL and nuclear maturation assessed by Hoechst 33342 or DAPI staining and the measurement of progesterone (P4) level in the maturation medium. We showed that vaspin and GRP78 protein expression increased in oocytes and cumulus cells after IVM. Moreover, vaspin enhanced significantly porcine oocyte IVM and P4 concentration, as well as MAP3/1 phosphorylation, while decreasing PRKAA1. Using pharmacological inhibitors of MAP3/1 (PD98059) and PRKAA1 (Compound C), we observed that the effect of vaspin was reversed to the control level by all studied parameters. In conclusion, vaspin, by improving in vitro oocyte maturation via MAP3/1 and PRKAA1 kinase pathways, can be a new factor to improve in vitro fertilisation protocols.

Adipokines expression profiles in both plasma and peri renal adipose tissue in Large White and Meishan sows: A possible involvement in the fattening and the onset of puberty

In pig, backfat deposition is strongly related to the growth and reproductive performance. However, the molecular regulatory mechanisms of adipose tissue are not clearly understood. Adipose tissue is now recognized as an important endocrine organ that secretes a variety of factors including adipokines. However, the regulation of expression pattern of these adipokines in both plasma and visceral white adipose tissue (WAT) in lean and fat pig is unclear. In the present study, we used two representative porcine breeds (Large White, LW; Meishan, MS) with contrasting backfat thickness and sexual maturity age. Using specific ELISA assays, we determined the plasma profile of eight adipokines, leptin, adiponectin, visfatin, apelin, chemerin, resistin, omentin and vaspin in LW and MS sows. By RT-qPCR and western-blot we also investigated the mRNA and protein levels of these adipokines and their cognate receptors (LEPR, ADIPOR1, ADIPOR2, CMKLR1, CCRL2, GPR1, APLNR, TLR4, ROR1, CAP1 and HSPA5) in the peri renal WAT, respectively. At both plasma and peri renal WAT level, we found that the amounts of leptin, chemerin, resistin and vaspin were higher whereas those of adiponectin and omentin were lower in MS than LW sows. Plasma and adipose tissue visfatin and apelin levels were not different between the two breeds. Moreover, we noted that the variations of peri renal WAT adipokines observed between MS and LW were similar at the protein and mRNA level except for chemerin and apelin suggesting post-transcriptional modifications for these two adipokines. Finally, among the eight adipokines studied, we showed that only the plasma concentrations of leptin and chemerin were positively and those of adiponectin, negatively associated with the thickness of fat and opposite correlation was found for the onset of puberty in both LW and MS animals. Taken together, these results support a potential involvement of adipokines in WAT regulation and its link with the onset of the puberty in sows.

The role of adipokines in the modulation of lymphoid lineage cell development and activity: An overview

Adipokines are predominantly known to play a vital role in the control of food intake, energy homeostasis and regulation of glucose and lipid metabolism. However, evidence supporting the concept of their extensive involvement in immune system defence mechanisms and inflammatory processes continues to grow. Some of the adipokines, that is, leptin and resistin, have been recognized to exhibit mainly pro-inflammatory properties, whereas others such as visfatin, chemerin, apelin and vaspin have been found to exert regulatory effects. In contrast, adiponectin or omentin are known for their anti-inflammatory activities. Hence, adipokines influence the activity of various cells engaged in innate immune response and inflammatory processes mainly by affecting adhesion molecule expression, chemotaxis, apoptosis and phagocytosis, as well as mediators production and release. However, much less is known about the role of adipokines in processes involving lymphoid lineage cells. This review summarizes the current knowledge regarding the importance of different adipokines in the lymphopoiesis, recirculation, differentiation and polarization of lymphoid lineage cells. It also provides insight into the influence of selected adipokines on the activity of those cells in tissues.

Novel Insights on the Corpus Luteum Function: Role of Vaspin on Porcine Luteal Cell Angiogenesis, Proliferation and Apoptosis by Activation of GRP78 Receptor and MAP3/1 Kinase Pathways

Formation and limited lifespan of corpus luteum (CL) are important for proper ovarian periodicity and fertility. Failed vascularization, imbalance between proliferation and apoptosis leads to luteal phase deficiency and infertility. The aim of this study was to examine the effect of vaspin on angiogenesis, apoptosis and proliferation as well as the involvement of 78-kDa glucose-regulated protein receptor (GRP78) and mitogen-activated kinase (MAP3/1) in these processes. Porcine luteal cells were incubated with vaspin (0.1-10 ng/mL) for 24 h to 72 h and then mRNA and protein expression of angiogenesis: vascular endothelial growth factor (VEGFA), fibroblast growth factor 2 (FGF2), angiopoietin 1 (ANGPT1), VEGFA receptors (VEGFR1, VEGFR2), apoptosis: caspase 3, bcl-2-like protein 4 (BAX), B-cell lymphoma (BCL2), and proliferation: proliferating cells nuclear antigen (PCNA), cyclin A factors as well as secretion of VEGFA, FGF2, ANGT1 were measured by real-time polymerase chain reaction (PCR), immunoblotting and enzyme-linked immunosorbent assay (ELISA), respectively. Moreover, apoptosis was assessed by caspase activity using the Caspase-Glo 3/7 assay, while proliferation was by alamarBlue. We found that vaspin enhanced luteal cell angiogenesis, proliferation, and significantly decreased apoptosis. Additionally, using GRP78 siRNA and the pharmacological inhibitor of MAP3/1 (PD98059), we observed that the effect of vaspin was reversed to the control level in all investigated processes. Taken together, our results suggest that vaspin is a new regulator of female fertility by direct regulation of CL formation and maintenance of luteal cell function.

The adipokine vaspin is associated with decreased coronary in-stent restenosis in vivo and inhibits migration of human coronary smooth muscle cells in vitro

BACKGROUND

Percutaneous coronary intervention represents the most important treatment modality of coronary artery stenosis. In-stent restenosis (ISR) is still a limitation for the long-term outcome despite the introduction of drug eluting stents. It has been shown that adipokines directly influence vessel wall homeostasis by influencing the function of endothelial cells and arterial smooth muscle cells. Visceral adipose tissue-derived serpin vaspin was recently identified as a member of serine protease inhibitor family and serveral studies could demonstrate a relation to metabolic diseases. The aim of this study was to investigate a role of vaspin in the development of in-stent restenosis in vivo and on migration of smooth muscle cells and endothelial cells in vitro.

METHODS

We studied 85 patients with stable coronary artery disease who underwent elective and successful PCI with implatation of drug eluting stents. Blood samples were taken directly before PCI. Vaspin plasma levels were measured by specific ELISA. ISR was evaluated eight months later by coronary angiography. Human coronary artery smooth muscle cells (HCASMC) and human umbilical vein endothelial cells (HUVEC) migration was analyzed by an in-vitro migration assay with different concentrations (0.004ng/mL up to 40ng/mL) of vaspin as well as by an scratch assay. For proliferation an impedance measurement with specialiced E-Plates was performed.

RESULTS

During the follow up period, 14 patients developed ISR. Patients with ISR had significantly lower vaspin plasma levels compared to patients without ISR (0.213 ng/ml vs 0.382 ng/ml; p = 0.001). In patients with plasma vaspin levels above 1.35 ng/ml we could not observe any restenosis. There was also a significant correlation of plasma vaspin levels and late lumen loss in the stented coronary segments. Further we could demonstrate that vaspin nearly abolishes serum induced migration of HCASMC (100% vs. 9%; p<0.001) in a biphasic manner but not migration of HUVEC. Proliferation of HCASMC and HUVEC was not modulated by vaspin treatment.

CONCLUSION

We were able to show that the adipokine vaspin selectively inhibits human coronary SMC migration in vitro and has no effect on HUVEC migration. Vaspin had no effect on proliferation of HUVEC which is an important process of the healing of the stented vessel. In addition, the occurrence of ISR after PCI with implantation of drug eluting stents was significantly associated with low vaspin plasma levels before intervention. Determination of vaspin plasma levels before PCI might be helpful in the identification of patients with high risk for development of ISR after stent implantation. In addition, the selective effects of vaspin on smooth muscle cell migration could potentially be used to reduce ISR without inhibition of re-endothelialization of the stented segment.

Insulin induces expression of the hepatic vaspin gene

Visceral adipose tissue-derived serine protease inhibitor (vaspin), initially identified in the visceral adipose tissue, is an adipokine that improves endoplasmic reticulum stress in obesity or insulin sensitivity and glucose tolerance. However, the transcriptional regulation of the hepatic vaspin gene remains elusive. We have previously shown that CCAAT-enhancer-binding protein α, a transcription factor of the basic leucine zipper class, positively regulates the vaspin gene. The present study aimed to investigate the nutritional or hormonal regulators of vaspin expression in the liver. For the fasting and refeeding study, mice in the fasting group were subjected to fasting for 24 h and then sacrificed. Mice in the refeeding group were subjected to fasting for 24 h and then refed with a 50% (w/w) sucrose/MF diet for further 24 h and then sacrificed. For the streptozotocin (STZ) study, STZ (50 mg/kg) was intraperitoneally injected into C57BL/6JJc1 mice for 5 d. Hepatic vaspin was repressed due to fasting for 24 h and was induced upon refeeding with a high-sucrose diet. In studies on liver-specific C/EBPα-deficient mice, C/EBPα was not involved in the induction of hepatic vaspin upon refeeding. In addition, the depletion of insulin by streptozotocin treatment markedly decreased hepatic vaspin expression. Finally, fasting-repressed vaspin expression in the liver was significantly increased by direct injection of insulin into fasting mice. In conclusion, our results suggest that insulin is a positive regulator of hepatic vaspin expression.

Serum Vaspin as a Predictor of Adverse Cardiac Events in Acute Myocardial Infarction

Background

The involvement of vaspin (visceral adipose tissue–derived serpin) in the development of atherosclerotic cardiovascular diseases has been documented. This study was designed to explore the prognostic value of serum vaspin in patients with acute myocardial infarction (AMI).

Methods and Results

We included 1036 AMI patients in a cohort study and determined the association between serum vaspin and major adverse cardiac events (MACE) using Cox regression analysis. The receiver operating characteristic curve indicated that serum vaspin could significantly differentiate patients with MACE, and the optimal cutoff value was 0.62 ng/mL. The Kaplan–Meier survival curve showed that patients with lower vaspin levels had higher incidence of MACE. Multivariate Cox regression analysis revealed that low vaspin was an independent predictor of MACE (hazard ratio: 0.74; 95% CI, 0.48–0.96; P=0.029), together with age; previous histories of AMI, heart failure, hypertension, and diabetes mellitus; Killip class; revascularization; CRP (C‐reactive protein); and NT‐proBNP (N‐terminal pro–B‐type natriuretic peptide). Integrated discrimination and net reclassification improvements for MACE were significantly improved by addition of vaspin to the model of traditional risk factors. Moreover, low vaspin was a valuable predictor of heart failure hospitalization (hazard ratio: 0.58; 95% CI, 0.37–0.89; P=0.005) and recurrent AMI (hazard ratio: 0.72; 95% CI, 0.53–0.95; P=0.036) after adjustment for conventional cardiovascular risk factors.

Conclusions

Our study suggests that serum vaspin is a significant prognostic marker of MACE in AMI patients.

Associations between Vaspin Levels and Coronary Artery Disease

The relationship between serum vaspin levels and metabolic or coronary artery disease is currently of interest for researchers. Although adipokine concentrations have been shown to be increased significantly in atherosclerotic lesions, the role adipokines in the atherosclerotic process remains to be elucidated. Vaspin is a new biological marker associated with obesity and impaired insulin sensitivity. Plasma vaspin concentration has been shown to correlate with the severity of coronary artery disease. Vascular inflammation triggered by vaspin inhibits atherogenesis by suppressing macrophage foam cell formation and vascular smooth muscle cell migration and proliferation. Vaspin also contributes to plaque stabilization by increasing collagen content and reducing the intraplaque macrophage to vascular smooth muscle cell ratio. The therapeutic goal concerning vaspin is to fight atherosclerosis and related diseases, as well as to maintain vascular health.

Screening and Risk Assessment of Coronary Artery Disease in Patients With Type 2 Diabetes: An Updated Review

Current literature indicates that there is a strong correlation between coronary artery disease (CAD) and type 2 diabetes. The arteriosclerotic progression occurs earlier and in a greater extent in the diabetic than in the non-diabetic population. In diabetic subjects, the detection of arterial disease does not always precede the development of an acute arterial incident. Herein, we reviewed studies published within the last 5 years in order to reveal the risk factors for coronary artery disease in patients with type 2 diabetes. In addition, we aimed to discuss how to diagnose in an early stage or even screen the presence of coronary artery disease in asymptomatic diabetic patients. Possible blood markers as predictors of CAD, which are mostly related to the lipidemic profile of subjects, are included in this review. Less invasive imaging methods than conventional coronary angiography, included in the article, are gradually used more in the diagnosis of CAD and show high effectiveness. Data from 23 articles with 22,350 patients having type 2 diabetes were summarized and presented descriptively.

In Vitro Effects of Vaspin on Porcine Granulosa Cell Proliferation, Cell Cycle Progression, and Apoptosis by Activation of GRP78 Receptor and Several Kinase Signaling Pathways Including MAP3/1, AKT, and STAT3

Vaspin, a visceral adipose tissue-derived serine protease inhibitor, is expressed in the porcine ovary; it induces the activation of various kinases and steroidogenesis. The aim of this study was to examine the effect of vaspin on granulosa (Gc) proliferation, cell cycle regulation, and apoptosis. Porcine Gc was incubated with vaspin (0.01-10 ng/mL) for 24 to 72 h, proliferation was measured using alamarBlue assay, cell cycle progression was assessed using flow cytometry, and cyclin (D, E, and A) protein expression was measured using immunoblotting. Apoptosis was assessed by measuring caspase activity using Caspase-glo 3/7 assay. Furthermore, histone-associated DNA fragments levels were measured using a cell-death detection ELISA; BAX (bcl-2-like protein 4), BCL2 (B-cell lymphoma 2), caspases (-3, -8, and -9), p53 mRNA, and protein expression were assessed using real time PCR and immunoblotting. We found that vaspin significantly enhanced Gc proliferation and cell cycle progression into the S and G2/M phases and decreased apoptosis. We observed that siRNA silencing of the glucose-regulated protein (GRP78) receptor and pharmacological inhibitors of mitogen-activated kinase (MAP3/1/ERK1/2), Janus kinase (STAT3) and protein kinase B (AKT) blocked the ability of vaspin cell proliferation and enhanced caspase-3/7 activities. These results suggest that vaspin via mitogenic effect on porcine Gc acts as a new regulator of ovarian growth, development, or folliculogenesis.

Cell Surface GRP78 as a Death Receptor and an Anticancer Drug Target

Cell surface GRP78 (csGRP78, glucose-regulated protein 78 kDa) is preferentially overexpressed in aggressive, metastatic, and chemo-resistant cancers. GRP78 is best studied as a chaperone protein in the lumen of endoplasmic reticulum (ER), facilitating folding and secretion of the newly synthesized proteins and regulating protein degradation as an ER stress sensor in the unfolded protein pathway. As a cell surface signal receptor, multiple csGRP78 ligands have been discovered to date, and they trigger various downstream cell signaling pathways including pro-proliferative, pro-survival, and pro-apoptotic pathways. In this perspective, we evaluate csGRP78 as a cell surface death receptor and its prospect as an anticancer drug target. The pro-apoptotic ligands of csGRP78 discovered so far include natural proteins, monoclonal antibodies, and synthetic peptides. Even the secreted GRP78 itself was recently found to function as a pro-apoptotic ligand for csGRP78, mediating pancreatic β-cell death. As csGRP78 is found to mainly configur as an external peripheral protein on cancer cell surface, how it can transmit death signals to the cytoplasmic environment remains enigmatic. With the recent encouraging results from the natural csGRP78 targeting pro-apoptotic monoclonal antibody PAT-SM6 in early-stage cancer clinical trials, the potential to develop a novel class of anticancer therapeutics targeting csGRP78 is becoming more compelling.

Beyond adiponectin and leptin: adipose tissue-derived mediators of inter-organ communication

The breakthrough discoveries of leptin and adiponectin more than two decades ago led to a widespread recognition of adipose tissue as an endocrine organ. Many more adipose tissue-secreted signaling mediators (adipokines) have been identified since then, and much has been learned about how adipose tissue communicates with other organs of the body to maintain systemic homeostasis. Beyond proteins, additional factors, such as lipids, metabolites, noncoding RNAs, and extracellular vesicles (EVs), released by adipose tissue participate in this process. Here, we review the diverse signaling mediators and mechanisms adipose tissue utilizes to relay information to other organs. We discuss recently identified adipokines (proteins, lipids, and metabolites) and briefly outline the contributions of noncoding RNAs and EVs to the ever-increasing complexities of adipose tissue inter-organ communication. We conclude by reflecting on central aspects of adipokine biology, namely, the contribution of distinct adipose tissue depots and cell types to adipokine secretion, the phenomenon of adipokine resistance, and the capacity of adipose tissue to act both as a source and sink of signaling mediators.

Nesfatin-1 and Vaspin as Potential Novel Biomarkers for the Prediction and Early Diagnosis of Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is considered to be one of the most frequent medical complication observed among pregnant women. The role of adipokines in the pathogenesis of GDM remains strictly unknown. Different adipokines have been studied throughout gestation, and they have been proposed as biomarkers of GDM and other pregnancy-related complications; however, there is no biomarker reported for GDM screening at present. The aim of this study was to evaluate serum nesfatin-1 and vaspin levels in GDM and non-GDM women, to characterize the correlation between these adipokines, and to assess the potential role of circulating adipokines in the prediction of risk of gestational diabetes mellitus. Serum concentrations of nesfatin-1 and vaspin were measured in 153 women with GDM, and in 84 patients with uncomplicated pregnancy by enzyme-linked immunosorbent assay (ELISA) kits, according to the manufacturer's instructions. Circulating levels of nesfatin-1 and vaspin were significantly lower in the GDM group than in the control group. Nesfatin-1 levels were negatively correlated with vaspin levels. The results of this study point out the possible role of nesfatin-1 and vaspin as potential novel biomarkers for the prediction and early diagnosis of GDM. Further studies are necessary to evaluate the influence of nesfatin-1 and vaspin on glucose metabolism in the early stages of GDM.

Adipocytokine Involvement in Innate Immune Mechanisms

The innate immune response is defined as an immensely complex and sophisticated process aimed at defending the organism against any disturbance in the body homeostasis, including invading pathogens. It requires a close cooperation of a vast amount of different cell types, recognized as inflammatory migrating cells, as well as stationary cells that form tissues. Moreover, innate immune mechanisms require an efficient functioning of various humoral components that exert a significant impact on physiological and pathological processes. Apart from commonly mentioned humoral factors, this group also includes a family of proteins known as adipocytokines that may act as pro- or anti-inflammatory agents or act both ways. Leptin, predominantly characterized as a proinflammatory adipokine, plays a crucial role in endothelium remodeling and regulation, as well as in cell survival and production of numerous cytokines. Adiponectin, similar to leptin, acts on the endothelial cells and the phagocytic properties of immune cells; however, it exerts an anti-inflammatory impact. Resistin has a documented role in the control of angiogenesis and stimulation of proinflammatory mediator generation and release. Furthermore, there are adipokines, ie, visfatin and chemerin, whose participation in the inflammatory processes is ambiguous. This review focuses on the current knowledge on the extensive role of selected adipokines in innate immune response.

Vaspin alleviates myocardial ischaemia/reperfusion injury via activating autophagic flux and restoring lysosomal function

Visceral adipose tissue-derived serine protease inhibitor (vaspin), as a secretory adipokine, was reported to exert a protective role on insulin resistance. Recent studies showed that serum vaspin level was downregulated in patients with coronary artery disease. However, whether vaspin exerted specific effects on myocardial injury remains unknown. In this study, we determined to explore the role of vaspin overexpression in myocardial ischaemia/reperfusion (I/R) injury and the underlying mechanisms. Our results showed that the systemic delivery of adeno-associated virus-vaspin to mice reduced myocardial infarct size and apoptosis, and improved cardiac function after reperfusion, accompanied with upregulated autophagic flux and restored lysosomal function in the ischaemic heart. Blockage of the autophagic flux with choroquine mitigated the protection of vaspin on myocardial I/R injury. Moreover, we testified that administration of exogenous recombinant human vaspin on cultured cardiomyocytes suppressed hypoxia/reoxygenation-induced apoptosis, through the AMPK-mTOR-upregulated autophagic flux. Overall, we verified that vaspin functions as an adipokine which can alleviate I/R injury in the heart by suppressing myocardial apoptosis through AMPK-mTOR-dependent activation of autophagic flux, and then provided a potential breakthrough in the treatment of myocardial I/R injury and other ischaemic diseases.

Anti-Atherogenic Effects of Vaspin on Human Aortic Smooth Muscle Cell/Macrophage Responses and Hyperlipidemic Mouse Plaque Phenotype

Vaspin (visceral adipose tissue-derived serine protease inhibitor) was recently identified as a novel adipocytokine with insulin-sensitizing effects. Serum vaspin levels are reported either increased or decreased in patients with coronary artery disease. Our translational research was performed to evaluate the expression of vaspin in human coronary atherosclerotic lesions, and its effects on atherogenic responses in human macrophages and human aortic smooth muscle cells (HASMC), as well as aortic atherosclerotic lesion development in spontaneously hyperlipidemic Apoe−/− mice, an animal model of atherosclerosis. Vaspin was expressed at high levels in macrophages/vascular smooth muscle cells (VSMCs) within human coronary atheromatous plaques. Vaspin significantly suppressed inflammatory phenotypes with nuclear factor κB down-regulation in human macrophages. Vaspin significantly suppressed oxidized low-density lipoprotein-induced foam cell formation with CD36 and acyl-coenzyme A: cholesterol acyltransferase-1 down-regulation and ATP-binding cassette transporters A1 and G1, and scavenger receptor class B type 1 up-regulation in human macrophages. Vaspin significantly suppressed angiotensin II-induced migration and proliferation with ERK1/2 and JNK down-regulation, and increased collagen production with phosphoinositide 3-kinase and Akt up-regulation in HASMCs. Chronic infusion of vaspin into Apoe−/− mice significantly suppressed the development of aortic atherosclerotic lesions, with significant reductions of intraplaque inflammation and the macrophage/VSMC ratio, a marker of plaque instability. Our study indicates that vaspin prevents atherosclerotic plaque formation and instability, and may serve as a novel therapeutic target in atherosclerotic cardiovascular diseases.

Vaspin suppresses cytokine-induced inflammation in 3T3-L1 adipocytes via inhibition of NFκB pathway

Vaspin expression is increased in white adipose tissue (WAT) of diet-induced obese mice and rats and is supposed to compensate HFD-induced inflammatory processes and insulin resistance in adipose tissue by counteracting pro-inflammatory gene expression in obesity. Multiple studies have also demonstrated strong anti-inflammatory effects in vascular and skin cells. Here, we used vaspin treated 3T3-L1 murine adipocytes as well as 3T3-L1 cells with stable vaspin expression to investigate the effect of exogenous and endogenous vaspin on inflammatory processes and insulin signaling in adipocytes. Our stably transfected cells secreted significant amounts of vaspin which was in the physiological range of ∼0.5 ng/ml in cell supernatants. Adipocyte differentiation was not affected by vaspin as expression of adipogenic marker genes as well as lipid accumulation after full differentiation was similar to control cells. We found that IL-1β induced expression and secretion of pro-inflammatory cytokines, such as IL-6, MCP1 and TNFα was significantly blunted in vaspin expressing 3T3-L1 cells. Treatment of 3T3-L1 cells with exogenous vaspin resulted in reduced cytokine-induced activation of the intracellular and pro-inflammatory NFκB signaling cascades (IKKα/β, IκB and NFκB). Moreover, endogenous vaspin positively affected insulin signaling by increasing insulin-stimulated phosphorylation of the key mediator protein kinase B (AKT). Together, we demonstrate anti-inflammatory effects of vaspin in 3T3-L1 adipocytes as well as increased insulin signaling by endogenous expression or exogenous treatment. The results provide evidence for potent anti-inflammatory action of vaspin not only in vascular cells but also in adipose tissue.

Molecular Mechanisms of Vaspin Action - From Adipose Tissue to Skin and Bone, from Blood Vessels to the Brain

Visceral adipose tissue-derived serine protease inhibitor (vaspin) or SERPINA12 according to the serpin nomenclature was identified together with other genes and gene products that were specifically expressed or overexpressed in the intra-abdominal or visceral adipose tissue (AT) of the Otsuka Long-Evans Tokushima fatty rat. These rats spontaneously develop visceral obesity, insulin resistance, hyperinsulinemia and -glycemia, as well as hypertension and thus represent a well suited animal model of obesity and related metabolic disorders such as type 2 diabetes.The follow-up study reporting the cloning, expression and functional characterization of vaspin suggested the great and promising potential of this molecule to counteract obesity induced insulin resistance and inflammation and has since initiated over 300 publications, clinical and experimental, that have contributed to uncover the multifaceted functions and molecular mechanisms of vaspin action not only in the adipose, but in many different cells, tissues and organs. This review will give an update on mechanistic and structural aspects of vaspin with a focus on its serpin function, the physiology and regulation of vaspin expression, and will summarize the latest on vaspin function in various tissues such as the different adipose tissue depots as well as the vasculature, skin, bone and the brain.

Plasminogen kringle 5 suppresses gastric cancer via regulating HIF-1α and GRP78

Inhibition of tumour angiogenesis has an important role in antitumour therapy. However, a recent study indicates that antiangiogenesis therapy may lead to glucose-related protein 78 (GRP78) associated antiapoptotic resistance. The present study aims to elucidate the dual effects of plasminogen kringle 5 (K5) on tumour angiogenesis and apoptosis induction by targeting hypoxia-inducible factor 1α (HIF-1α) and GRP78. Co-immunoprecipitation and western blotting were used for examining the ubiquitination of HIF-1α and analysing angiogenesis and apoptosis-associated proteins. K5 promoted the sumo/ubiquitin-mediated proteasomal degradation of HIF-1α by upregulating von Hippel-Lindau protein under hypoxia, resulting in the reduction of vascular endothelial growth factor and thus suppressing tumour angiogenesis. Furthermore, K5 decreased GRP78 expression via downregulation of phosphorylated extracellular-regulated protein kinase, leading to caspase-7 cleavage and tumour cell apoptosis. Blocking voltage-dependent anion channel abrogated the effects of K5 on both HIF-1α and GRP78. K5 significantly inhibited the growth of gastric carcinoma xenografts by inhibiting both angiogenesis and apoptosis. The dual effects suggest that K5 might be a promising bio-therapeutic agent in the treatment of gastric cancer, particularly in patients who exhibit the induction of GRP78.

Vaspin protects against LPS‑induced ARDS by inhibiting inflammation, apoptosis and reactive oxygen species generation in pulmonary endothelial cells via the Akt/GSK‑3β pathway

Acute respiratory distress syndrome (ARDS) is characterized by uncontrolled extravasation of protein-rich fluids, which is caused by disruption and dysfunction of the barrier of pulmonary endothelial cells (ECs). Visceral adipose tissue-derived serine protease inhibitor (vaspin) is a novel adipokine with pleiotropic properties, which has been reported to exert beneficial effects against obesity-associated systemic vascular diseases; however, its effects on ARDS remain unknown. In the present study, mice were subjected to systemic administration of adenoviral vector expressing vaspin (Ad-vaspin) to examine its effects on lipopolysaccharide (LPS)-induced ARDS in vivo. Histological analysis was then conducted, and cytokine [tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-10] levels, and intercellular cell adhesion molecule-1 (ICAM-1) and adherens junctions (AJs) expression were detected. In addition, human pulmonary microvascular ECs (HPMECs) were treated with recombinant human (rh)-vaspin to further investigate its molecular basis and underlying mechanism. The mRNA expression levels of inflammatory cytokines (TNF-α and IL-6) and endothelial-specific adhesion markers [vascular cell adhesion molecule-1 and E-selectin], activation of nuclear factor-κB, and cell viability and apoptosis were then examined. Furthermore, the expression of AJs and organization of the cytoskeleton, as well as expression and activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and generation of reactive oxygen species (ROS) were determined. The results indicated that Ad-vaspin protected against LPS-induced ARDS by alleviating the pulmonary inflammatory response and pulmonary EC barrier dysfunction in mice, which was accompanied by activation of the protein kinase B (Akt)/glycogen synthase kinase (GSK)-3β pathway. In addition, pretreatment of HPMECs with rh-vaspin attenuated inflammation, apoptosis and ROS generation without alterations in AJs and cytoskeletal organization following LPS insult, which was accompanied by activation of the Akt/GSK3β pathway. In conclusion, the present study demonstrated that vaspin protects against LPS-induced ARDS by reversing EC barrier dysfunction via the suppression of inflammation, apoptosis and ROS production in pulmonary ECs, at least partially via activation of the Akt/GSK3β pathway. These findings provide evidence of a causal link between vaspin and EC dysfunction in ARDS, and suggest a potential therapeutic intervention for patients with ARDS.

Voltage-Dependent Anion Channel 1 As an Emerging Drug Target for Novel Anti-Cancer Therapeutics

Cancer cells share several properties, high proliferation potential, reprogramed metabolism, and resistance to apoptotic cues. Acquiring these hallmarks involves changes in key oncogenes and non-oncogenes essential for cancer cell survival and prosperity, and is accompanied by the increased energy requirements of proliferating cells. Mitochondria occupy a central position in cell life and death with mitochondrial bioenergetics, biosynthesis, and signaling are critical for tumorigenesis. Voltage-dependent anion channel 1 (VDAC1) is situated in the outer mitochondrial membrane (OMM) and serving as a mitochondrial gatekeeper. VDAC1 allowing the transfer of metabolites, fatty acid ions, Ca²⁺, reactive oxygen species, and cholesterol across the OMM and is a key player in mitochondrial-mediate apoptosis. Moreover, VDAC1 serves as a hub protein, interacting with diverse sets of proteins from the cytosol, endoplasmic reticulum, and mitochondria that together regulate metabolic and signaling pathways. The observation that VDAC1 is over-expressed in many cancers suggests that the protein may play a pivotal role in cancer cell survival. However, VDAC1 is also important in mitochondria-mediated apoptosis, mediating release of apoptotic proteins and interacting with anti-apoptotic proteins, such as B-cell lymphoma 2 (Bcl-2), Bcl-xL, and hexokinase (HK), which are also highly expressed in many cancers. Strategically located in a “bottleneck” position, controlling metabolic homeostasis and apoptosis, VDAC1 thus represents an emerging target for anti-cancer drugs. This review presents an overview on the multi-functional mitochondrial protein VDAC1 performing several functions and interacting with distinct sets of partners to regulate both cell life and death, and highlights the importance of the protein for cancer cell survival. We address recent results related to the mechanisms of VDAC1-mediated apoptosis and the potential of associated proteins to modulate of VDAC1 activity, with the aim of developing VDAC1-based approaches. The first strategy involves modification of cell metabolism using VDAC1-specific small interfering RNA leading to inhibition of cancer cell and tumor growth and reversed oncogenic properties. The second strategy involves activation of cancer cell death using VDAC1-based peptides that prevent cell death induction by anti-apoptotic proteins. Finally, we discuss the potential therapeutic benefits of treatments and drugs leading to enhanced VDAC1 expression or targeting VDAC1 to induce apoptosis.

Serum vaspin level as a predictive indicator in the amelioration of fatty liver and metabolic disturbance in patients with severe obesity after laparoscopic vertical banded gastroplasty

BACKGROUND

This study is all about predicting the value of serum vaspin level in the amelioration of fatty liver and metabolic disturbance in patients with severe obesity after laparoscopic vertical banded gastroplasty (LVBG).

METHODS

A total of 164 patients (from January 2012 to May 2015) with severe obesity were chosen and performed LVBG. Enzyme-linked immunosorbent assay was performed to detect the serum vaspin level. The patients were given a biochemical automatic analyzer to measure the biochemical indicators. Homeostasis model assessment (HOMA) helps in the calculation of fasting insulin level (FINS) and insulin resistance (IR). The changes in fatty liver were examined by computed tomography (CT). Receiver operating characteristic curve is used to increase the predictive value of serum vaspin level in the amelioration of liver function and disturbances in the metabolism.

RESULTS

Weight, BMI, waist circumference, serum vaspin level, and triglyceride (TG) decreased, but CT value of liver increased at 4th, 7th, and 12th month after surgery. After the 7th and 12th month period of surgery, the alanine aminotransferase, aspartate aminotransferase, FINS, and HOMA-IR reduced in the patients (P <.005). The area under ROC curve (AUC) is about 0.871 ± 0.031 with 95%CI of 0.810-0.931 (P <.001). The sensitivity, specificity, and accuracy of serum vaspin level ≤0.9 were 87.80%, 78.05%, and 83.28%, respectively. BMI, FINS, and serum vaspin level ≤0.9 were the influencing factors of the amelioration of fatty liver and metabolic disturbance.

CONCLUSION

This study proves that the serum vaspin level serves as a predictive indicator in the amelioration of fatty liver and metabolic disturbance in patients with severe obesity after LVBG.

Glycosylation of human vaspin (SERPINA12) and its impact on serpin activity, heparin binding and thermal stability

Vaspin is a glycoprotein with three predicted glycosylation sites at asparagine residues located in proximity to the reactive center loop and close to domains that play important roles in conformational changes underlying serpin function. In this study, we have investigated the glycosylation of human vaspin and its effects on biochemical properties relevant to vaspin function. We show that vaspin is modified at all three sites and biochemical data demonstrate that glycosylation does not hinder inhibition of the target protease kallikrein 7. Although binding affinity to heparin is slightly decreased, the protease inhibition reaction is still significantly accelerated in the presence of heparin. Glycosylation did not affect thermal stability.

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.

Low vaspin levels are related to endothelial dysfunction in patients with ankylosing spondylitis

Vaspin is a novel adipocytokine associated with glucose tolerance and chronic inflammation. Some studies reveal that vaspin may be involved in cardiovascular diseases. Our objective was to investigate the relationship between serum vaspin levels and endothelial function in patients with ankylosing spondylitis. One hundred and twenty patients with newly diagnosed ankylosing spondylitis and 100 healthy subjects were studied. Serum vaspin levels were measured with enzyme-linked immunosorbent assay. High resolution ultrasound was used to measure brachial artery diameter at rest, after reactive hyperemia (flow-mediated dilation, FMD) and after sublingual glyceryltrinitrate. Serum vaspin level in patients was 1.92±1.03 ng/mL, which was significantly lower than that in healthy subjects (2.88±0.81 ng/mL). By dividing the distribution of serum vaspin levels into quartiles, FMD levels increased gradually with the increase of serum vaspin levels in patients (P<0.01). Univariate analysis showed a correlation between vaspin and FMD (r=0.73, P=0.003), low-density lipoprotein cholesterol (r=-0.45, P=0.033), high-density lipoprotein cholesterol (r=0.63, P=0.025), fasting blood glucose (r=-0.79, P=0.006), triglycerides (TG) (r=-0.68, P=0.036), systolic blood pressure (r=-0.35, P=0.021), C-reactive protein (r=-0.67, P=0.011), homeostatic model assessment of insulin resistance (HOMA-IR) (r=-0.77, P=0.023) and erythrocyte sedimentation rate (r=-0.88, P=0.039) in patients. Multivariate analysis indicated that serum vaspin levels were independently associated with FMD, HOMA-IR and TG in patients. Our study found that serum vaspin levels were decreased in patients with ankylosing spondylitis and were associated with FMD levels. Vaspin may serve as an independent marker for detecting early stage atherosclerosis in patients with ankylosing spondylitis.

The role of vaspin as a predictor of coronary angiography result in SCAD (stable coronary artery disease) patients

BACKGROUND

The role of vaspin in the pathogenesis of stable coronary artery disease (SCAD) have been repeatedly addressed in clinical studies. However, from the point of view of clinical practice, the results of earlier studies are still inconclusive.

METHODS

The data of 106 SCAD patients who received coronary angiography and 85 coronary artery disease-free controls were collected and analysed. The patients were divided into subgroups according to their pre-test probability (PTP) and according to the result of coronary angiography. Fasting vaspin concentrations were compared between subgroups of SCAD patients and between target group and controls. The effect of age and smoking on the result of coronary angiography was compared to the effect of vaspin using the binomial regression.

RESULTS

We did not find significant difference in vaspin level between target group and controls. Unless the pre-test probability was taken into account, we did not find vaspin difference in the target group, when dividing patients on the basis of presence/absence of significant coronary stenosis. In the subgroup of SCAD patients with PTP between 15% - 65%, those with significant coronary stenoses had higher mean vaspin concentration (0,579 ± 0,898 ng/ml) than patients without significant stenoses. (0,379 ± 0,732 ng/ml) (t = -2595; p = 0,012; d = 0,658; 1-β = 0,850). Age, smoking status and vaspin significantly contributed to the HSCS prediction in binomial regression model in patients with low PTP (OR: 1.1, 4.9, 8.7, respectively).

CONCLUSION

According to our results, vaspin cannot be used as an independent marker for the presence of CAD in general population. However, our results indicate that measuring vaspin in SCAD patients might be clinically useful in patients with PTP below 66%.

Impact of age on plasma vaspin concentration in a group of normal Chinese people

PURPOSE

Visceral adipose tissue-derived serine protease inhibitor (vaspin) is an adipocytokine with insulin-sensitizing effects. Accumulating data implied that vaspin represents a compensatory mechanism but it is unknown how vaspin change during ageing. This study was designed to examine the correlation between plasma vaspin and age in a group of normal Chinese people.

METHODS

A total of 191 Chinese volunteers aged 19-80 years were enrolled into four groups based upon age quartiles (19-35, 36-50, 51-65 and 66-80 years). Demographic, anthropometric, metabolic covariates, vaspin and adiponectin were measured. The influence of age on plasma vaspin was analysed using SPSS 13.0.

RESULTS

Vaspin increased with ageing, with mean vaspin levels (ng/mL) of 1.01 ± 2.25, 1.67 ± 2.95, 2.05 ± 3.46 and 2.40 ± 3.06 for those between quartile ages 19-35, 36-50, 51-65 and 66-80 years. When divided into subgroups, vaspin increased with increasing age for both sexes, both insulin resistance and non-insulin resistance subjects and both obese and lean subjects. In univariate analyses, vaspin plasma level positively associated with age (r = 0.215, p = 0.003), adiponectin, insulin, homoeostasis model of assessment for insulin resistance index and waist-hip ratio in the whole population. The correlation between ageing and increasing vaspin remained significant after multivariate adjustments for factors such as sex, body mass index, waist-hip ratio, indices of glucose metabolism, white blood cell, lipid profile and adiponectin. Stepwise multiple regression analysis showed that age contributed 7.6 % on plasma vaspin level.

CONCLUSION

Vaspin level increased with ageing, independent of sex, indices of glucose metabolism, lipid profile and other markers of adiposity.

Basic Residues of β-Sheet A Contribute to Heparin Binding and Activation of Vaspin (Serpin A12)

Many members of the serine protease inhibitor (serpin) family are activated by glycosaminoglycans (GAGs). Visceral adipose tissue-derived serpin (vaspin), serpin A12 of the serpin family, and its target protease kallikrein 7 (KLK7) are heparin-binding proteins, and inhibition of KLK7 by vaspin is accelerated by heparin. However, the nature of GAG binding to vaspin is not known. Here, we measured vaspin binding of various glycosaminoglycans and low molecular weight heparins by microscale thermophoresis and analyzed acceleration of protease inhibition by these molecules. In addition, basic residues contributing to heparin binding and heparin activation were identified by a selective labeling approach. Together, these data show that vaspin binds heparin with high affinity (K_D = 21 ± 2 nm) and that binding takes place at a basic patch on top of β-sheet A and is different from other heparin-binding serpins. Mutation of basic residues decreased heparin binding and activation of vaspin. Similarly, reactive center loop insertion into sheet A decreased heparin binding because it disturbs the basic cluster. Finally, using vaspin-overexpressing keratinocyte cells, we show that a significant part of secreted vaspin is bound in the extracellular matrix on the cell surface. Together, basic residues of central β-sheet A contribute to heparin binding and activation of vaspin. Thus, binding to GAGs in the extracellular matrix can direct and regulate vaspin interaction with target proteases or other proteins and may play an important role in the various beneficial functions of vaspin in different tissues.

Assessment of Serum VASPIN Levels among Type 2 Diabetes Mellitus Patients with or without Acute Coronary Syndrome

INTRODUCTION

Type 2 Diabetes Mellitus (DM) is on the verge of becoming a pandemic in India. Type 2 DM patient have two to four times increased risk of carotid artery disease. Adipokines have been regarded recently as direct link between diabetes and atherosclerosis. Visceral Adipose Tissue Derived Serine Protease Inhibitor (VASPIN); one of the most recently discovered adipokine, inhibits the proteases responsible for insulin resistance, carotid plaque development and rupture. In literature, few studies have addressed the role of VASPIN in pathogenesis of Acute Coronary Syndrome (ACS) in patients with type 2 DM.

AIM

To find association between serum VASPIN with lipid profile, creatine kinase-total, creatine kinase-MB, troponin-I, age, height, weight, blood pressure, smoking, family history of ACS and to prove the hypothesis of low serum VASPIN level as predictor of ACS in patients with type 2 DM.

MATERIALS AND METHODS

Forty-one type 2 DM patients (controls) and 41 type 2 DM patients with ACS (cases) were enrolled in the study. Anthropometric measurements were performed and fasting serum biochemical parameters and VASPIN were measured. The results of cases and controls were compared by student t-test or Mann-Whitney test. All the parameters were correlated with serum VASPIN by Pearson's or Spearman's correlation.

RESULTS

Fasting serum VASPIN concentration was significantly (p< 0.0001) lower in the cases (0.43±0.22 pg/ml) than in the controls (0.83±0.29 pg/ml). Correlation analysis undertaken on all type 2 DM showed that serum VASPIN concentration was negatively correlated with age, waist circumference, hip circumference, systolic and diastolic blood pressure, duration of diabetes, serum Creative Kinase-Total, CK-MB and urea (p< 0.05). Utilizing Receiver Operating Characteristic (ROC) curve, the serum VASPIN level of less than 0.594pg/ml showed greatest risk of ACS among type 2 DM patients (p< 0.0001).

CONCLUSION

Type 2 DM patients with low serum vaspin concentration were at risk of ACS independent of other cardiovascular risk factors.

Vaspin prevents elevation of blood pressure through inhibition of peripheral vascular remodelling in spontaneously hypertensive rats

AIM

Visceral adipose tissue-derived serine protease inhibitor (vaspin) is a relatively novel adipocytokine with protective effects on metabolic diseases including obesity and type II diabetes. We have previously demonstrated that vaspin exerts anti-inflammatory and antimigratory roles through antioxidative effects in vascular smooth muscle cells. As inflammatory responses and migration of smooth muscle in peripheral vascular wall are key mechanisms for the pathogenesis of hypertension, we hypothesized that vaspin could prevent the development of hypertension in in vivo hypertensive animal model.

METHODS

Vaspin (1 μg kg(-1)  day(-1) ) was administered intraperitoneally to 5-week-old male spontaneously hypertensive rats (SHR) for 4 weeks. Superior mesenteric artery was isolated and used for measurement of isometric contraction and histological analysis.

RESULTS

Long-term vaspin treatment significantly prevented an elevation of systolic blood pressure (SBP) at 8 weeks of age. Vaspin had no effect on reactivity of isolated mesenteric artery from SHR. In contrast, vaspin significantly inhibited mesenteric arterial wall hypertrophy in SHR. Moreover, vaspin significantly inhibited an increase of tumour necrosis factor-α expression and a production of reactive oxygen species in isolated mesenteric artery from SHR.

CONCLUSION

This study for the first time demonstrates that vaspin prevents the increase of SBP in SHR through inhibiting peripheral vascular hypertrophy possibly via antioxidative and anti-inflammatory mechanisms.

Vaspin regulates the osteogenic differentiation of MC3T3-E1 through the PI3K-Akt/miR-34c loop

Vaspin (visceral adipose tissue-derived serine protease inhibitor) is a newly discovered adipokine that widely participates in diabetes mellitus, polycystic ovarian syndrome and other disorders of metabolism. However, the effect of vaspin on the regulation of osteogenesis and the mechanism responsible are still unclear. Here, we found that vaspin can attenuate the osteogenic differentiation of the preosteoblast cell line MC3T3-E1 in a dose-dependent way; also, during this process, the expression of miRNA-34c (miR-34c) was significantly increased. Down-regulation of the expression of miR-34c in MC3T3-E1 diminished the osteogenic inhibitory effect of vaspin, while the up-regulation of miR-34c increased this effect through its target gene Runx2. Meanwhile, we found that vaspin could also activate the PI3K-Akt signalling pathway. Blocking the PI3K-Akt signalling pathway with specific inhibitors could decrease the osteogenic inhibitory effect of vaspin as well as the expression level of miR-34c. Furthermore, knock-down of miR-34c could promote the activation of Akt, which was probably realised by targeting c-met expression. Thus, PI3K-Akt and miR-34c constituted a modulation loop and controlled the expression of each other. Taken together, our study showed that vaspin could inhibit the osteogenic differentiation in vitro, and the PI3K-Akt/miR-34c loop might be the underlying mechanism.