Molecular mechanism of inhibitory effects of CD59 gene on atherosclerosis in ApoE (-/-) mice.

BACKGROUND: How to find an effective gene locus resistant to atherosclerosis has become a hotspot of today's medicine. Membrane attack complex (MAC) has proved to be related with the occurrence and development of atherosclerosis. Complement regulatory protein CD59 is a key regulator of complement MAC assembly. So this study aimed at discussing the effects of CD59 gene on occurrence and development of atherosclerosis and relative mechanism.

METHODS: Apolipoprotein E knockout (ApoE (-/-)) mice were randomly divided into four groups: control group, empty plasmid-treated group, 0.5 ml CD59-treated group and 1.0 ml CD59-treated group. At the end of the 12th week, CD59 mRNA levels in whole blood were determined by RT-PCR and CD59 protein expressions were detected by western blot. The biochemical indexes in blood serum were detected. The paraffin sections of aortic root of mice were made and the degrees of atherosclerotic plaques formation were observed by hematoxylin/eosin (HE) staining. The expressions of cell apoptosis-related proteins (Bcl-2 and Fas) and plaque stability related protein (MMP-2) were detected by immunohistochemistry. Then the cell apoptosis levels were detected by TUNEL, the expression of Cyclin D1 and the mRNA level of cyclin dependent protein kinase 4 (CDK4) were detected by immunofluorescence and in situ hybridization, respectively.

RESULTS: Atherosclerotic mouse model was successfully established. CD59 gene was overexpressed in blood cells and tissue cells after liposome transfection. CD59 could reduce blood lipid levels, promote the expression of anti-apoptotic Bcl-2 protein and inhibit pro-apoptotic Fas proteins, so finally lead to degradation of apoptosis levels of endothelial cells. In addition, Cyclin D1 protein and CDK4 mRNA levels were restrained by CD59 so as to inhibit the proliferation of smooth muscle cells. CD59 could inhibit the formation of atherosclerotic vulnerable plaque by suppressing the MMP-2 expression, which was further confirmed by HE staining. The anti-atherosclerotic effects were enhanced with the increase of CD59 gene dose.

CONCLUSIONS: CD59 could lower blood lipid levels, positively regulate cell cycle, maintain the stability of cell proliferation and apoptosis of aorta cells, slow down the development of atherosclerotic vulnerable plaque, and finally inhibit the progress of atherosclerosis. So CD59 gene might be a new genetic locus for the therapy of atherosclerosis.