Anti-aging Effects Of Simvastatin On Vascular Endothelial Cells Via Upregulation Of SIRT1

Background: Aging is the body’s response to multiple factors in the internal andexternal environment. For example, radiation, hypoxia, peroxidation, hyperglycemia, andhyperlipidemia have been shown to cause aging. Studies have shown that oxidized lowdensity lipoprotein (OX-LDL) is an important contributor to the aging process. Higherlevel of OX-LDL increases the degree of aging of endothelial progenitor cells. In humans,OX-LDL level increases gradually with age. Inhibition of OX-LDL has been shown toreduce the degree of cellular aging. Therefore, reduction of OX-LDL concentration andOX-LDL antagonists have anti-aging effects. A number of markers of aging have beenreported, including telomerase, β-galactosidase, and SIRT1genes. Of these markers,SIRT1plays an important role in gene silencing, stress resistance, and prolongation of thelife span. The SIRT1gene plays an important role in aging, and knockout of this gene mayaccelerate aging in animals. In human umbilical vein endothelial cells, SIRT1knockout orinhibition of SIRT1activity can induce manifestations of aging. Over-expression of theSIRT1gene can decrease cellular aging. Simvastatin is widely used clinically and hasanti-inflammatory, anti-oxidative, anti-arteriosclerosis, and endothelium protective actions,suggesting that simvastatin may have anti-aging effects via upregulation of SIRT1.Objective: To investigate the anti-aging effects of simvastatin and its regulatoryeffects on expression of SIRT1in endothelial cells.Methods: Detection was carried out in vivo and in vitro cell studies. In vivo, Sixteenaged rats（60-week-old） were randomly divided into two groups, one group on a normaldiet and one group given oral simvastatin5mg/kg/d, mixed as a powder into their food.Eight10-week-old rats on a normal diet were included as a control youth group. Theexperimental (simvastatin or normal) diet was given for16weeks, and plasma OX-LDLconcentrations in the aged group (n=8), the aged group taking oral simvastatin (n=8),and youth group (n=8) were measured. Aortic β-galactosidase staining was performed. Invitro, umbilical vein endothelial cells were divided into two groups: In the OX-LDL group,the cells were cultured with different concentrations of OX-LDL (0,25,50and100μg/ml) for24hours, and the results of β-galactosidase staining and SIRT1expression were observed.In the simvastatin group, the cells were cultured for24hours, each group was pre-treatedwith different concentrations of simvastatin for1h(0μM,1μM,5μM and10μM), andthen100mg/L OX-LDL was added for additional23hours, and added a control group.-galactosidase staining and SIRT1expression in the presence of the different concentrations of simvastatin were then determined.Results: In vivo, untreated aged rats had significantly higher levels of cholesterol,LDL and OX-LDL than young rats. Sixteen weeks of oral simvastatin treatment of theaged rats significantly lowered their levels of these lipids compared to levels in theuntreated aged group(TC:103.43±15.14vs.147.25±10.59, P=0.002, LDL:10.36±1.47vs12.21±1.48，P=0.008, OX-LDL:18.45±2.64vs.25.06±2.53, P=0.001). The percentage ofcells with positive β-galactosidase staining was significantly increased in aged compared toyoung rats (83.67±9.50%vs.22.00±2.65%, P<0.001).Administration of simvastatin to agedrats significantly lowered the percentage compared to that in untreated aged rats(68.83±7.47%vs.83.67±9.50%, P=0.001). After simvastatin therapy, aging of arterialendothelial cells was significantly improved. In vitro, in the OX-LDL group, asconcentrations of OX-LDL were increased, the number of cells with positive β–galactosidase staining increased significantly with a maximum increase when theOX-LDL concentration was100μg/ml. In this high OX-LDL group(P<0.001), SIRT1protein expression was significantly decreased compared to those in the low concentrationgroup and no OX-LDL group (P=0.001). In the simvastatin group, pretreatment ofsimvastatin (10μM) significantly decreased OX-LDL-induced aging in cells treated with100μg/ml OX-LDL(P<0.001), and significantly inhibited OX-LDL-induced decrease ofSIRT1protein expression(P<0.001). The degree of these effects was dependent on thedosage of simvastatin.Conclusions: Simvastatin treatment could significantly improve aging of the arterialendothelial cells. Simvastatin could block the OX-LDL-induced down-regulation of SIRT1and improve the aging of umbilical vein endothelial cells. Therefore, our results confirmthe anti-aging effects of simvastatin on vascular endothelial cells in vivo and in vitro. Thepossible mechanism is related to increased SIRT1expression in endothelial cells. Theresults may provide a new theoretical basis for studying the function of statins andunderstanding the mechanism of simvastatin in decreasing pathophysiology seen inatherosclerosis.