家兔颈动脉内膜损伤后血管平滑肌细胞表型转化及p38的表达变化

Phenotypic modulation of vascular smooth muscle cells and expression of p38 mitogen-activated protein kinase after intimal injury of rabbit carotid arteries

目的观察动脉内膜损伤后血管平滑肌细胞（VSMC）表型转化及其与p38表达的关系。方法分别用HE染色、免疫组化和免疫印迹（Western blot）方法检测家兔假损伤组（S组）和损伤组损伤后不同时间点血管形态学改变及血管壁中增殖细胞核抗原（PCNA）、平滑肌α肌动蛋白（SMα—actin）和p38蛋白表达的变化。结果（1）内膜损伤后1d血管中膜管腔侧、3d管腔内表面可见增殖的VSMC，5～7d新生内膜（NI）形成并逐渐增厚，14～35d NI进行性增厚。各组中膜均有增殖的VSMC向腔面集聚。（2）S组动脉中膜VSMC及内皮细胞PCNA为阴性。中膜于损伤后1～14d，NI于5～14d PCNA阳性细胞率逐渐增加，14d达高峰，28d后开始逐渐减少，且NI阳性率略高于中膜。（3）S组动脉中膜SMα—actin表达为阳性，内皮细胞为阴性。SMα—actin阳性面积于损伤后1d开始减少，3d最为明显，5d后开始逐渐增加，NI阳性表达略低于中膜。（4）S组动脉中膜p38较少或无表达，损伤后1～35d呈持续高表达，以3～14d最为明显，NI阳性表达略高于中膜。损伤后p38表达变化与PCNA表达变化呈正相关，且早于SMα—actin表达减少。结论内膜损伤后VSMC增殖能力与其表型转化密切相关，p38参与了损伤后VSMC表型转化的信号转导。

Objective To explore phenotypic modulation of vascular smooth muscle cells （VSMC） and change of p38 mitogen-activated protein kinase （MAPK） expression after intimal injury of rabbit carotid arteries. Methods The model of vascular restenosis established by balloon injury of rabbit carotid common arteries was used. HE staining, immunohistochemistry staining and Western blot were used to detect the change of proliferation cell nuclear antigen （PCNA）, smooth muscle α-actin （SMα-actin）, p38 expression and morphology of sham-injured arteries and injured arteries at different time points. Results （1）The proliferating VSMC was observed on the side of the medium lumen at 1 day and on the surface of vascular lumen at 3 days after injury. The neointima was formed and gradually being thicken at 5 ～ 7 days, and the thickening was accelerated at 14 ～ 35 days after injury. （2）PCNA was negative in the medium and endothelium of sham-injured arteries. Positive cell rate of PCNA was gradually increased at 1 ～ 14 days in the medium and at 5 ～ 14 days in the neointima after injury, with the maximum rate at 14 days. However, it declined gradually after 28 days. Positive cell rate of PCNA in the neointima was slightly higher than that in the medium. （3）SMα-actin was positive in the medium, negative in the endothelium of sham-injured arteries. Positive cell area of SMα-actin initially decreased at 1 day in the medium after injury with the minimum rate at 3 days, but it increased gradually after 5 days. Expression of SMα-actin in the neointima was slightly less than that in the medium. （4）p38 expression was very low or negative in the medium of sham-injured arteries. Expression of p38 was sustained and increased at 1 ～ 35 days after injury with the most remarkable elevation at 3 ～ 14 days. Expression of p38 in the neointima was higher than that in the medium. There was positive relationship between the p38 expression and PCNA expression in the vascular wall at different time points after injury. Elevation of p38 was earlier than decrease of SMα- actin. Condusion There was a close relationship between the phenotypic modulation and proliferating ability of VSMC. P38 participated in signal transduction of phenotypic modulation of VSMC after intimal injury.