Effects Of Atorvastatin And Rapamycin On HO-1 Expression And Vascular Smooth Muscle Cell Proliferation

Background Heme oxygenase-1 which serves as the starting and rate-limiting enzyme for heme metabolism has anti-inflammatory,antioxidant and antiproliferative actions. Evidences have shown that HO-1 can inhibit vascular smooth muscle cell (VSMC) proliferation. Atorvastatin is one of the most effective statins, which can also inhibit VSMC proliferation. The mechanism responsible for atorvastatin's inhibiting VSMC proliferation is not completely understood. It has not been reported whether atorvastatin can inhibit VSMC proliferation through inducing HO-1 expression.Objective This study is aimed to explore effects of atorvastatin on the expression of heme oxygenase-1 (HO-1) and the proliferation of VSMC, to confirm the signal pathway of atorvastatin inducing HO-1 and to investigate the effects of HO-1 induced by arorvastatin on VSMC proliferation.Methods VSMC cultured from SD rats were cultured by enzymatic dissociation methods. The purity of cultured VSMC was assessed morphyologically and confirmed by immunocytochemical staining for a-actin. Subcultures between 4 and 6 (p4-6) were used in the study. Insulin-like growth factor-Ⅰwas used to stimulate VSMC proliferation. The alive cell counting by trypan blue dye staining and tetrazolium dye-reduction assay(MTT) were used to determine the effect of arorvastatin on VSMC proliferation at different concentration (0,0.01,0.1,1,10μmol/L ), the same methods were used to do with 10μmol/L atorvastatin combination with ZnPPⅨ. Atorvastatin (10μmol/L) was added one hour after pretreatment with PD980593 or LY294002 or/and SB203580. HO-1 protein were detected by the method of immunocytochemitry. The level of HO-1mRNA was assessed by the method of RT-PCR.Results Proliferation of VSMC was decreased with the increase ofatorvastatin concentration. ZnPPⅨ, a special inhibitor of HO-1, could partially reverse the inhibition of atorvastatin. The increase of the expression in HO-1 was dependent on the dose of atorvastatin. SB203580 and LY294002 markly reduced the level of HO-1 induced by atorvastatin, but PD98059 showed little effect.Conclusion Atorvastatin could inhibit VSMC proliferation. Atorvastatin could induce the expression of HO-1. Inducing HO-1 expression was one of the mechanisms responsible for atorvastatin inhibiting VSMC proliferation. P38 and PI3K were involved in the atorvastatin-induced increase of HO-1 in VSMC. Background Vessel neointima formation whcich caused by VSMC proliferation is a main factor contributing to restenosis after percutaneous intervention. Present study has shown that HO-1 can inhibit VSMC proliferation. A new immunosuppressive agent, rapamycin is widely used in drug-eluting stent for more than ten years to prevent restenosis through inhibiting VSMC proliferation, but the mechanism of rapamycin inhibiting VSMC proliferation is not completely understood. This study is aimed to explore whether rapamycin inhibit VSMC proliferation through inducing the expression of HO-1.Objective This study was to observe effects of rapamycin on the expression of heine oxygenase-1 (HO-1) and the proliferation of VSMC, and to investigate effects of HO-1 induced by rapamycin on VSMC proliferation.Methods Subcultures between 4 and 6 (p4-6) were used in the study. Insulin-like growth factor-Ⅰwas used to stimulate VSMC proliferation. The alive cell counting by trypan blue dye staining and tetrazolium dye-reduction assay(MTT) were used to determine the effect of rapamycin on VSMC proliferation at different concentration (0,0.01,0.1,1,10μmol/L) , the same methods were used to do with rapamycin (10μmol/L) alone or combination with atorvastatin(10μmol/L) with or without ZnPPⅨ. HO-1 protein was detected by the method of immunocytochemitry. The level of HO-1mRNA was assessed by the method of RT-PCR.Results Proliferation of VSMC was decreased with the increase of rapamycin concentration. Rapamycin combination with atorvastatin showed stronger function on the inhibiting VSMC proliferation. ZnPPⅨ,a special inhibitor of HO-1, could greatly reverse the inibition of rapamycin. Dose-effect dependent increase was found in the expression of HO-1 induced by rapamycin .Compaired with rapamycin alone, rapamycin combination with atorvastatin showed stronger function on the expression of HO-1.Conclusion Rapamycin could inhibit VSMC proliferation. Rapamycin could induce the expression of HO-1. Inducing HO-1 exprssion was one of the main mechanisms responsible for rapamycin inhibiting VSMC proliferation. Rapamycin combination with atorvastatin showed stronger function on the expression of HO-1and the inhibiting proliferation of VSMC. Background Percutaneous luminal coronary angioplasty(PTCA) is the main method of coronary heart disease treatment. Many patients suffered from restenosis which is still a significant problem in the practice of interventional cardiology after PTCA. VSMC proliferation and neointimal formation are the main reason for restenosis. It is reported that HO-1 can inhibit vascular smooth muscle cell proliferation and neointimal formation. Present study has shown that atorvastatin and rapamycin can partially prevent restenosis. It is not well known whether the preventing restenosis action of atorvastatin/rapamycin is related to the expression of HO-1 induced by them.Objective This study is to observe the expression of HO-1 of carotid artery after Balloon injury with or without the administration of atorvastatin and/or rapamycin, and to investigate the effect of HO-1 induced by atorvastatin and rapamycin on the neointimal proliferation after balloon injury.Methods: Fourty-eight SD rats were randomly divided into ordinary control group, atorvastatin with or without ZnPPⅨgroup, rapamycin with or without ZnPPⅨgroup, rapamycin and atorvastatin with or without ZnPPIX group and injuries without treatment group. The left carotid artery was injured by balloon, the right one was acted as control. The rats were sacrificed after 28 days. The intimal and medial layer's proliferation were examined by measure after the vessel stained by HE, and the area of the intimal and medial layer were caculated.The level of HO-1 expression was assessed by immunohistochemical metheods and RT-PCR.Results The neointimal proliferation could be obviously obsvered in the injured carotid artery, but the similar change was not observed in the control vessel. The area of intimal layers, the ratio of the intimal and the medial layers in the atorvastatin group as well as rapamycin group, atorvastatin combination with rapamycin group was significantly lower than that in the injured group without treatment. ZnPPⅨ, the inhibitor of HO-1, could reverse the effect of atorvastatin and/or rapamycin on the proliferation of the intimal layer. The expression of HO-1 was much higher in the group of atorvastatin,rapamycin,atorvastatin combination with rapamycin, as compared with the untreated group. In addition, the combination of atorvastatin and rapamycin had the best similar effect.Conclusion The rat carotid model injured by balloon may be...