OXIDATIVELY MODIFIED LDL CONTAINS PHOSPHOLIPIDS WITH PLATELET-ACTIVATING FACTOR-LIKE ACTIVITY AND STIMULATES THE GROWTH OF SMOOTH-MUSCLE CELLS
OXIDATIVELY MODIFIED LDL CONTAINS PHOSPHOLIPIDS WITH PLATELET-ACTIVATING FACTOR-LIKE ACTIVITY AND STIMULATES THE GROWTH OF SMOOTH-MUSCLE CELLS
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DOI：
10.1172/jci118288
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发表时间：
1995-11-01
影响因子：
15.9
通讯作者：
PRESCOTT, SM
中科院分区：
文献类型：
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作者：
HEERY, JM;KOZAK, M;PRESCOTT, SM
脂蛋白的氧化修饰被认为在动脉粥样硬化的发生中是重要的。我们建立了平滑肌细胞（SMC）的培养物，并将其暴露于天然LDL或氧化LDL。通过[H-3]-胸苷掺入DNA测定，氧化LDL（而非天然LDL）具有促有丝分裂作用。这种作用是浓度依赖性的，平均为对照的288%，并被血小板活化因子（PAF）受体拮抗剂阻断。我们推测，具有PAF样活性的磷脂在LDL氧化过程中产生。为了验证这一假设，我们从铜氧化LDL中提取磷脂，并测定PAF样活性。从氧化LDL中提取磷脂，并通过HPLC纯化，诱导中性粒细胞粘附相当于PAF（10 nM），并对平滑肌细胞有丝分裂原。从天然LDL中提取的磷脂没有观察到这些作用，并且被两种结构不同的PAF受体竞争性拮抗剂阻断。这些脂质的作用也通过用PAF乙酰水解酶预处理而被消除。最后，我们使用已经稳定转染PAF受体的cDNA的中国仓鼠卵巢细胞来证实来自氧化LDL的磷脂通过该受体起作用。我们发现PAF（对照）和氧化磷脂各自诱导从转染的细胞释放花生四烯酸，但对缺乏PAF受体的野生型中国仓鼠卵巢细胞无作用，这种作用也可被PAF受体拮抗剂阻断。因此，氧化修饰LDL过程中产生的磷脂可能通过刺激SMC增殖和白细胞活化参与动脉粥样硬化。
Oxidative modification of lipoproteins is believed to be important in the genesis of atherosclerosis. We established cultures of smooth muscle cells (SMC) and exposed them to native LDL or oxidized LDL. Oxidized LDL, but not native LDL, was mitogenic as measured by incorporation of [H-3]-thymidine into DNA. This effect was concentration dependent, averaged 288% of control, and was blocked by a platelet-activating factor (PAF) receptor antagonist. We hypothesized that phospholipids with PAF-like activity were generated during the oxidation of LDL. To test this hypothesis we extracted phospholipids from copper-oxidized LDL and assayed for PAF-like activity, Phospholipids extracted from oxidized LDL and purified by HPLC induced neutrophil adhesion equivalent to PAF (10 nM) and were mitogenic for smooth muscle cells. These effects were not seen with phospholipids extracted from native LDL and were blocked by two structurally different, competitive antagonists of the PAF receptor. The effects of these lipids were also abolished by pretreating them with PAF acetylhydrolase, Finally, we used Chinese hamster ovary cells that had seen stably transfected with a cDNA for the PAF receptor to confirm that phospholipids from oxidized LDL act via this receptor, We found that PAF (control) and the oxidized phospholipids each induced release of arachidonic acid from the transfected cells, but had no effect on wildtype Chinese hamster ovary cells, which lack the PAF receptor, This effect was also blocked by a PAF receptor antagonist. Thus, phospholipids generated during oxidative modification of LDL may participate in atherosclerosis by stimulating SMC proliferation and leukocyte activation.