氧化型低密度脂蛋白诱导大鼠血管平滑肌细胞凋亡

Oxidized Low Density Lipoprotein Induced Apoptosis of Vascular Smooth Cells

为研究氧化型低密度脂蛋白引起血管平滑肌细胞凋亡及其凋亡的机制，采用细胞形态学、ＤＮＡ末端标记法、流式细胞仪、Ｗｅｓｔｅｒｎｂｌｏｔｉｎｇ观察氧化型低密度脂蛋白诱导培养的大鼠血管平滑肌细胞凋亡。结果发现，在氧化型低密度脂蛋白作用下，血管平滑肌细胞阻滞在分裂期的中期，并发生凋亡。ＤＮＡ末端标记法和流式细胞仪检测发现氧化型低密度脂蛋白（２００ｍｇ／Ｌ）引起细胞凋亡指数明显高于天然低密度脂蛋白（前者是后者的１０倍）。电镜下凋亡细胞呈现核固缩或凋亡小体的形态学特征，脱氧核苷转移酶介导的ｄＵＴＰ切口末端标记法显示凋亡的细胞质或细胞核内有弥散性棕色阳性颗粒。氧化型低密度脂蛋白凋亡发生时，Ｐ５３蛋白呈高表达，而凋亡抑制基因ｂｃｌ２蛋白呈低表达。此结果提示，氧化型低密度脂蛋白诱导的血管平滑肌细胞的凋亡与细胞分裂期阻滞密切相关，Ｐ５３和ｂｃｌ２在氧化型低密度脂蛋白诱导的凋亡中可能发挥重要的调控作用。

Aim To investigate the apoptosis of vascular smooth muscle cells (VSMC) of rats induced by oxidized low density lipoprotein (ox LDL) and the mechanism of its action. Method The cell morphology, terminal deoxynucleotidy1 transferase mediated dUTP nick end labeling (TUNEL) assay, flow cytometry and Western blotting were performed for ox LDL inducing apoptosis of VSMC in rats. Results VSMC treated with ox LDL (200 mg/L) underwent the arrests of cell mitosis at metaphase, and the apoptosis index was as 10 times higher in VSMC treated with ox LDL as nLDL. The VSMC treated with ox LDL showed cell shrikage, condensation or fragmentation of chromosomes and apoptotic body. TUNEL assay showed brown and positive particles in apoptotic chromosomes and cytoplasma. The expression of P53 significantly increased, bcl 2 decreased in ox LDL treated cells. Conclusion Ox LDL induced apoptosis of VSMC, causing mitotic arrest of cells cycle, and promoting P53 and lowering bcl 2 gene expression. This indicated P53 and bcl 2 genes may play important role in VSMC' apoptosis induced by ox LDL.