Study On The Role Of Visfatin In Atherosclerosis

Objective:The aim of the present study was to investigate the pathophysiological links between plasma level of visfatin and endothelial function,and evaluate the significance of visfatin in genesis and development of atherosclerosis(AS).Methods:In the present study,215 patients including 55 patients received the PCI operations,who had undergone coronary angiography and ultrasound detection of carotid and brachial artery,were enrolled.The severities of coronary stenosis and carotid atherosclerosis were determined by coronary angiography and carotid ultrasound and carotid intima-media thickness(IMT),respectively.Based on the results of Gensini score,these patients were classified into four groups:control(no AS),mild AS,middle AS and severe AS groups.The flow mediated dilation(FMD) of brachial artery was also measured by color Doppler ultrasound.The plasma levels of both visfatin and asymmetric dimethylarginine(ADMA),a new marker of endothelial dysfunction, were determined by ELISA and HPLC,respectively.Results:Plasma level of visfatin in patients with severe AS was significantly higher than those in patients with middle AS,mild AS or in the control group.We confirmed these findings by linear regression analyses,plasma level of visfatin was positively correlated with carotid IMT,serum level of ADMA and Gensini score in all enrolled patients, and was negatively correlated with the FMD of brachial artery.Especially, the serum level of ADMA and visfatin was significantly decreased after the PCI operations.Conclusions:The present data firstly showed that plasma level of visfatin,which was markedly increased in the patient with AS,was correlated negatively with endothelial function and can reflect the severity of AS.Our present findings that visfatin is closely related to the genesis and development of AS suggest visfatin may be a new predictive factor of cardiovascular disease.Objective:Visfatin,a new adipocytokine,has been reported to promote angiogenesis.Dimethylarginine dimethylaminohydrolase (DDAH),which can upregulate vascular endothelial growth factor (VEGF) expression in endothelial cells,is thought as a novel modulator of angiogenesis.The aim of the study was to investigate the role of DDAH₂ in visfatin-induced angiogenesis in human umbilical vein endothelial cells(HUVECs).Methods:HUVECs were incubated with different concentrations of visfatin(0.1-3 nM) for 6-24 hours.We detected the capabilities of migration and tube formation in HUVECs to judge the angiogenic effects of visfatin.Quantitative real time PCR was used to detect the expression of DDAH₂ and VEGF mRNA.The level of ADMA was measured by high-performance liquid chromatography and the level of NO was determined indirectly as the content of nitrite and nitrate using NO assay kits.The level of VEGF was detected by the ELISA kit.DDAH₂ siRNA was used to interference the expression of mRNA and protein of DDAH₂. The phosphorylation of Akt and the protein expression of DDAH₂ were determined by western blot analysis.Results:Visfatin concentration- and time-dependently enhanced cell migration and tube formation reflecting angiogenic capability of HUVECs.Moreover,visfatin upregulated the expression of DDAH₂ and VEGF(both mRNA and protein).Angiogenic effects of visfatin were attenuated by DDAH₂ small interfering RNA Visfatin induced protein kinase B(Akt) phosphorylation and phosphoinositide 3 kinase(PI3K) inhibitors could suppress visfatin-induced upregulation of the expression ofDDAH₂ and VEGF.Conclusions:Taken together,our results suggest that PI3K/Akt-mediated upregulation of DDAH₂ expression plays a critical role in visfatin-promoted angiogenesis via regulating VEGF-dependent pathway. Objective:Visfatin is a new adipocytokine.Recent studies have shown that visfatin enables to inhibit the endothelial cells aging via upregulating the expression of SIRT1.In coronary heart disease patients, endothelial progenitor cells(EPCs) have the impairment of proliferative, migratory capacity and network formation,and the number of circulating EPCs is reduced,suggesting that EPCs plays a critical role in genesis and development of atherosclerosisMethods:EPCs were isolated by density gradient centrifugation from human cord blood mononuclear cells,and cultured in EBM-2 supplemented with EGM-2 Single-Quots.Adherent EPCs were characterized by dual staining for acetylated low-density lipoprotein (ac-LDL) and ulex europaeus agglutinin-1(UEA-1),and by flow cytometry detecting the stem cell marker CD34+ and vWF or by immunofluorescent analysis.After incubation of EPCs with different concentrations of visfatin(0.1-10 nM) for 24 hours,we detected the capabilities of migration and tube formation in EPCs to judge the angiogenic effects of visfatin.Quantitative real time PCR was used to detect the expression of SIRT1 mRNA and western blot analysis was used to detect the protein level of SIRT1.To quantitatively analyze telomerase activity,we used a Quantitative Telomerase Detection Kit to perform telomeric repeat amplification protocol(TRAP) assay according to the supplier's instructio.Senescent Cells Staining Kit was used to determine the senescence-associatedβ-galactosidase activity.Intracellular oxidant productions were measured by using H2DCF,a fluoresent indicator.Results:(1) 0.1 nM and 1 nM visfatin could enhance cell migration and tube formation reflecting angiogenic capability of EPCs,the increased of migration and tube formation were decreased by 10 nM visfatin(compared with 1 nM visfatin).(2) 0.1 nM and 1 nM visfatin could upregulate the level of SIRT1 and telomerase activity(compared with control),the level of SIRT1 and telomerase activity were decreased with 3 and 10 nM visfatin(compared with 1 nM visfatin).(3) Senescence-associatedβ-galactosidase activity were significantly decreased with 0.1 nM visfatin(compared with control),β-galactosidase activity were increased with 3 and 10 nM visfatin(compared with 0.1 nM visfatin).(4) Visfatin could concentration-dependently enhance the level of ROS,pretreatment with the inhibitor of ROS production could inhibit the decrease level of SIRT1 and telomerase activity with 10 nM visfatin and the increase inβ-galactosidase activity.Conclusions:Visfatin at the physiological concentration could inhibit the EPCs aging,and the protection of EPCs aging were attenuated by the pathological concentration of visfatin via oxidative stress-mediated downregulation of the expression of SIRT1.