Müller K, Carpenter K L, Mitchinson M J
Department of Pathology, University of Cambridge, UK.
Free Radic Res. 1998 Sep;29(3):207-20. doi: 10.1080/10715769800300241.
The three major cell types of the human atherosclerotic lesion--macrophages (Mø), smooth muscle cells (SMC) and endothelial cells (EC)--were compared for their ability to oxidise low density lipoprotein (LDL) in vitro under identical conditions. Near-confluent cultures were incubated for up to 48 h with 50 microg protein/ml LDL in Ham's F10 medium supplemented with 7 microM Fe2+. All three cell types oxidised LDL readily using our culture conditions. After 24 and 48 h, the degree of LDL oxidation was in the order: Mø > SMC > EC when based on cell growth area and EC > SMC > Mo when based on cellular DNA content. However, LDL oxidation in vitro progressed more slowly between 24 and 48 h, probably due to increasing toxicity to the cells and/or depletion of polyunsaturated fatty acids. We therefore compared the time of onset of LDL oxidation. The earliest increase in LDL oxidation was always apparent with SMC. Gas chromatography revealed that LDL oxidation by all three cell types followed a similar pattern. The polyunsaturated fatty acids linoleic acid (18:2) and arachidonic acid (20:4) were depleted (to 10.3-18.1% and 4.5-24.7% respectively, compared to native LDL), whereas the content of stearic acid (18:0) and oleic acid (18:1) remained unchanged. Cholesterol was depleted (to 54.1-75.6% of native LDL) with a concomitant rise in 7 -hydroxycholesterol (to 60.6-128.1 microg/mg LDL). This corresponds to a conversion of 4.9, 9.5 and 10.4% of LDL cholesterol in EC-, SMC- and Mo-modified LDL respectively. All three cell types showed significant toxicity in the oxidising culture after 24h. The possible relevance to LDL oxidation in atherosclerosis is discussed.
在相同条件下，对人类动脉粥样硬化病变的三种主要细胞类型——巨噬细胞（Mø）、平滑肌细胞（SMC）和内皮细胞（EC）——在体外氧化低密度脂蛋白（LDL）的能力进行了比较。将接近汇合的细胞培养物在补充有7 microM Fe2+的Ham's F10培养基中，与50微克蛋白质/毫升的LDL一起孵育长达48小时。在我们的培养条件下，所有三种细胞类型都能轻易地氧化LDL。24小时和48小时后，基于细胞生长面积，LDL氧化程度的顺序为：Mø > SMC > EC；而基于细胞DNA含量，顺序为：EC > SMC > Mø。然而，体外LDL氧化在24小时至48小时之间进展较为缓慢，这可能是由于对细胞的毒性增加和/或多不饱和脂肪酸的消耗。因此，我们比较了LDL氧化开始的时间。最早出现的LDL氧化增加总是在SMC中最为明显。气相色谱分析表明，所有三种细胞类型对LDL的氧化遵循相似的模式。多不饱和脂肪酸亚油酸（18:2）和花生四烯酸（20:4）减少（与天然LDL相比，分别降至10.3 - 18.1%和4.5 - 24.7%），而硬脂酸（18:0）和油酸（18:1）的含量保持不变。胆固醇减少（降至天然LDL的54.1 - 75.6%），同时7 - 羟基胆固醇升高（升至60.6 - 128.1微克/毫克LDL）。这分别相当于EC -、SMC - 和Mø - 修饰的LDL中LDL胆固醇的4.9%、9.5%和10.4%的转化率。24小时后，所有三种细胞类型在氧化培养中均表现出显著的毒性。文中讨论了其与动脉粥样硬化中LDL氧化的可能相关性。
