Study On The Expression Of Cyclooxygenase-2 In Human Atherosclerosis And Cultured Vascular Smooth Muscle Cells

Backgrounds: Cyclooxygenase-2 (COX-2) and its prostaglandin productions play a pivotal role in inflammation, and have been implicated in the pathophysiology of cardiovascular disease, thus might be a potential target to prevent and cure atherosclerosis and acute coronary syndrome. However, C-reactive protein( CRP) is a strong predictor and important risk factor of cardiovascular disease, which can mediate inflammation involved in the full-stage of atherosclerosis process. The activation of increased inflammatory factors related to CRP may suggest a relation between inflammation and the stability of atherosclerotic plaque. Whether there is some interplay between COX-2 and CRP is still not known. In the contemporary view of atherosclerosis as an inflammatory disease, statins and aspirin have been regarded as anti-inflammatory agents which modulate the inflammation and immunoreactivity of atherosclerosis.Objectives: 1.To observe the expression of COX-2 and CRP in atherosclerosis lesions to explore the relation between COX-2 and CRP in the process of atherosclerosis. 2. To investigate the effects on the level of COX-2 mRNA and protein in cultured VSMCs treated with aspirin and fluvastatin Methods:Immnunohistochemical staining was used for location of antigens such as COX-2, CRP, CD68 and a-actin in different stage of atherosclerosis lesions. The distribution, degree of COX-2 expression colocalized with CRP was compared and the correlation between them was observed in arteriy specimens to investigate the contribution of COX-2 and CRP to the development of atherosclerosis and subsequent risks of plaque instability.Human umbilical artery smooth cells (HUASMCs) were isolated and cultured, with CRP treatment at specifical dose and to investigate the effects induced byCRP. In HUASMCs, the expression of COX-2 mRNA and protein induced by CRP were detected respectively by RT-PCR and immnunohistochemical staining to explore the relation between COX-2 and CRP. After that, treated with aspirin, fluvastatin and both of them, COX-2 mRNA and protein were measured to identify the anti-atherosclerosis potential of aspirin and fluvastatin and the cooperativity of the two drugs. Results:1 COX-2 and CRP were colocalized in the areas of plaques but not in healthy or nonatherosclerotic vascular walls, they were found in endothelial cells,macrophages and SMCs within atherosclerotic plaques. The expression of COX-2 and CRP in the lesions of early stage and late stage was significantly higher than that in normal arteries(P<0.05 and P<0.001, respectively). The level of COX-2 was significantly correlated with the level of CRP(P <0.05, R=0.224 ), which indicated that there might be some potential interplay between the two factors in the process of atherosclerosis.2 CRP increased the level of COX-2 mRNA in HUASMCs in a dose-dependent manner (P <0.05) in vitro, and also increased the expression of COX-2 protein in HUASMCs.3 Aspirin(0.5 mM, 1 mM, 2 mM and 5mM) , fluvastatin (0.1 u M,luM and 10 u M)and the combination of Aspirin( 2 mM) with fluvastatin (luM) all had significantly inhibitory effects on CRP (lOng/ml) induced COX-2 expression in HUASMCs (P<0.05) in vitro, while the combination of aspirin and fluvastatin could provide an enhanced inhibition that is superior to the respective monotherapy(p<0.05).Conclusions:1 COX-2 and CRP are both implicated in the inflammatory modulation ofatherosclerosis pathophysiology and plaque vulnerability, which suggeststhere may be some potential interplay between these two factors in the process of atherosclerosis. COX-2 is a new potential therapeutic target to treat atherosclerosis especially via increasing plaque stability.2 CRP can increase the level of COX-2 mRNA in HUASMCs in vitro in a dose-dependent manner and also increase the expression of COX-2 protein, which demonstrates that there is some interplay between COX-2 and CRP in the process of atherosclerosis.3 The monotherapy or combination of aspirin and fiuvastatin can decrease the expression of COX-2 mRNA and protein induced by CRP in HUASMCs in vitro to attenuate inflammation. The combination of asprin and fiuvastatin may have cooperativity in modulating the lipid and inhibiting the inflammation, which may be more beneficial to prevent and treat atherosclerosis and acute coronary events in the future.