Solakivi T, Jaakkola O, Salomäki A, Peltonen N, Metso S, Lehtimäki T, Jokela H, Nikkari S T
Department of Medical Biochemistry, University of Tampere, Medical School, Tampere, Finland.
Lipids Health Dis. 2005 Oct 20;4:25. doi: 10.1186/1476-511X-4-25.
Oxidative modification of low-density lipoprotein (LDL) is a key event in the oxidation hypothesis of atherogenesis. Some in vitro experiments have previously suggested that high-density lipoprotein (HDL) co-incubated with LDL prevents Cu2+-induced oxidation of LDL, while some other studies have observed an opposite effect. To comprehensively clarify the role of HDL in this context, we isolated LDL, HDL2 and HDL3 from sera of 61 free-living individuals (33 women and 28 men).
When the isolated LDL was subjected to Cu2+-induced oxidation, both HDL2 and HDL3 particles increased the rate of appearance and the final concentration of conjugated dienes similarly in both genders. Oxidation rate was positively associated with polyunsaturated fatty acid content of the lipoproteins in that it was positively related to the content of linoleate and negatively related to oleate. More saturated fats thus protected the lipoproteins from damage.
We conclude that in vitro HDL does not protect LDL from oxidation, but is in fact oxidized fastest of all lipoproteins due to its fatty acid composition, which is oxidation promoting.
低密度脂蛋白（LDL）的氧化修饰是动脉粥样硬化发生氧化假说中的关键事件。先前一些体外实验表明，与LDL共同孵育的高密度脂蛋白（HDL）可防止Cu2+诱导的LDL氧化，而其他一些研究则观察到相反的效果。为了全面阐明HDL在此过程中的作用，我们从61名自由生活个体（33名女性和28名男性）的血清中分离出LDL、HDL2和HDL3。
当分离出的LDL受到Cu2+诱导的氧化时，HDL2和HDL3颗粒在两性中均同样增加了共轭二烯的出现速率和最终浓度。氧化速率与脂蛋白的多不饱和脂肪酸含量呈正相关，因为它与亚油酸含量呈正相关，与油酸含量呈负相关。因此，更多的饱和脂肪可保护脂蛋白免受损伤。
我们得出结论，在体外，HDL并不能保护LDL免受氧化，实际上由于其促进氧化的脂肪酸组成，HDL是所有脂蛋白中氧化最快的。
