Girona Josefa, LaVille Agnes E, Solà Rosa, Motta Claude, Masana Lluís
Unitat de Recerca de Lípids i Arteriosclerosi, Facultat de Medicina, Hospital Universitari Sant Joan, Universitat Rovira i Virgili, C. Sant Llorenç, 21 43201 Reus, Spain.
Biochim Biophys Acta. 2003 Sep 22;1633(3):143-8. doi: 10.1016/s1388-1981(03)00108-2.
Oxidized HDL (ox-HDL) has been reported to reduce free cholesterol efflux from cells. In this study we investigate the effect of different stages of ox-HDL on macrophage membrane fluidity and its effect on free cholesterol efflux from macrophages as a cell function influenced by ox-HDL. HDL was oxidized by means of conjugated diene production using copper as a prooxidant. Fluidity of HDL and human THP-1 macrophage membranes was evaluated by changes in fluorescence anisotropy (r) by DPH probe where lower (r) values give higher fluidity. We found that ox-HDL derived from the propagation phase (PP-HDL) and the decomposition phase (DP-HDL) became less fluid ((r): 0.263+/-0.001, 0.279+/-0.002, respectively) than HDL from the lag phase (LP-HDL) and native HDL (nat-HDL) ((r): 0.206+/-0.001) (P<0.05). Macrophages incubated with PP-HDL and DP-HDL had less fluid membranes ((r): 0.231+/-0.001, 0.243+/-0.002, respectively) than those incubated with LP-HDL and nat-HDL ((r): 0.223+/-0.001) (P<0.05). Consequently, fluidity was reduced not only in ox-HDL but also in the cell membranes exposed to ox-HDL. A significant negative correlation was observed between macrophage membrane fluorescence anisotropy (r) and free cholesterol efflux from these cells (-0.876; P<0.05). Thus, lower membrane fluidity was associated with lower free cholesterol efflux from cells. In conclusion, the increase in the HDL oxidation process leads to a lost of macrophage membrane fluidity that could contribute to an explanation of the reduction of free cholesterol efflux from cells by ox-HDL.
据报道，氧化高密度脂蛋白（ox-HDL）会减少细胞内游离胆固醇的流出。在本研究中，我们探究了不同阶段的ox-HDL对巨噬细胞膜流动性的影响，以及其作为ox-HDL影响的细胞功能，对巨噬细胞游离胆固醇流出的作用。通过使用铜作为促氧化剂产生共轭二烯的方法将高密度脂蛋白氧化。利用DPH探针通过荧光偏振度（r）的变化评估高密度脂蛋白和人THP-1巨噬细胞膜的流动性，较低的（r）值表示流动性较高。我们发现，与来自迟滞期的高密度脂蛋白（LP-HDL）和天然高密度脂蛋白（nat-HDL）相比，来自增殖期的ox-HDL（PP-HDL）和分解期的ox-HDL（DP-HDL）流动性降低（（r）分别为：0.263±0.001，0.279±0.002）（（r）：0.206±0.001）（P<0.05）。与LP-HDL和nat-HDL孵育的巨噬细胞相比，与PP-HDL和DP-HDL孵育的巨噬细胞膜流动性较低（（r）分别为：0.231±0.001，0.243±0.002）（（r）：0.223±0.001）（P<0.05）。因此，不仅ox-HDL的流动性降低，而且暴露于ox-HDL的细胞膜流动性也降低。在巨噬细胞膜荧光偏振度（r）与这些细胞的游离胆固醇流出之间观察到显著的负相关（-0.876；P<0.05）。因此，较低的膜流动性与细胞中较低的游离胆固醇流出相关。总之，高密度脂蛋白氧化过程的增加导致巨噬细胞膜流动性丧失，这可能有助于解释ox-HDL导致细胞游离胆固醇流出减少的原因。
