转铁蛋白逆转血浆脂蛋白体外氧化修饰的研究

REVERSE EFFECT OF TRANSFERRIN ON THE OXIDATIVE MODIFICATION OF PLASMA LIPOPROTEIN INDUCED BY Cu^(2+) OR Fe^(2+) IN VITRO

目的 :观察转铁蛋白 (Tf)对体外已受到Cu2 + 、Fe2 + 修饰的人血浆高密度脂蛋白 (HDL)、低密度脂蛋白(LDL)和极低密度脂蛋白 (VLDL)氧化修饰的影响。方法 :采用一次性密度梯度超离心法分离正常人血浆HDL、LDL和VLDL ,在 37℃分别与CuSO4 及FeSO4 温育 6小时 ,使脂蛋白在体外氧化修饰。转铁蛋白组在氧化修饰后加入4 0 0 μg ml的Tf作用 8小时。检测三种脂蛋白中脂质过氧化产物丙二醛 (MDA) ,维生素E(VitE)含量及超氧化物歧化酶 (SOD)活性。结果 :①HDL、LDL和VLDL与Cu2 + 或Fe2 + 温育后 ,MDA含量显著升高 (P <0 .0 0 1) ,并呈明显的时间效应。②在Cu2 + 或Fe2 + 修饰后加入 4 0 0 μg ml的Tf能使明显降低HDL、LDL和VLDL中MDA生成 ,阻止VitE含量下降 ,并显著提高SOD活性 ,呈现一定的浓度依赖性。结论 :结果提示Tf能显著逆转Cu2 + 或Fe2 + 介导的血浆HDL、LDL和VLDL氧化修饰 ,可能为一内源性抗动脉粥样硬化因子。其作用途径可能与阻断Cu2 + 或Fe2 + 诱导的自由基生成 ,保护内源性抗氧化物质SOD、VitE的活性有关。

Objective: To observe the reverse effect of Transferrin(Tf) on the oxidative modification of high density lipoprotein(HDL) , low density lipoprotein(LDL) and very low density lipoprotein(VLDL) induced by Cu^(2+) or Fe^(2+) in vitro. Methods: Human HDL, LDL and VLDL were prepared by one-step ultracentrifuge and oxidated by Cu^(2+) or Fe^(2+) at 37℃ for 6h. Then Tf(400μg/ml) was added to HDL, LDL and VLDL respectively for 8h incubation. The contents of MDA, Vitamin E and activity of superoxide dismutase (SOD) in HDL,LDL and VLDL were determined. Results:After incubated with Cu^(2+) or Fe^(2+), the MDA production of 3 kinds of lipoprotein increased significantly, but the level of Vit E and SOD declined(P<0.001).Compared with OX-HDL, OX-LDL, OX-VLDL group , Tf could markedly decrease MDA content meanwhile elevate Vit E level and SOD activity after 8h treatment(P<0.001). Conclusion: This result indicates that Tf can obviously reverse the oxidative modificaon of HDL,LDL and VLDL already induced both by Cu^(2+) or Fe^(2+). The mechanism may be associated with its ability of blocking free radical process and protecting endogenous anti-oxidation agents such as Vit E and SOD.