Liu Cheng-wei, Hu Xin-hua, Yang Jun, Zhang Qiang, Zhang Xue-song, Duan Zhi-quan
Department of Vascular Surgery, First Affiliated Hospital, China Medical University, Shenyang 110001, China.
Zhonghua Yi Xue Za Zhi. 2005 Dec 21;85(48):3414-8.
To investigate the expression of early growth response gene-1 (Egr-1) and its correlative genes: platelet-derived growth factor-B (PDGF-B) gene and transforming growth factor-beta(1) (TGF-beta(1)) gene, in autogenous vein graft and the relationship of the expression of these genes to intimal hyperplasia (IH).
A segment of the right common jugular vein was transplanted to the infra-renal abdominal aorta of the same individual so as to establish an autogenous vein graft model in 90 Wistar rats. Vein samples were harvested 1, 2, 6, and 24 hours, 3 and 7 days, and 2, 4, and 6 weeks after the operation to undergo histological examination. In situ hybridization and RT-OCR were performed to examine the mRNA expression of Egr-1, PDGF-B, and TGF-beta(1). Western blotting and immunohistochemistry were used to detect the protein expression of Egr-1, PDGF-B, and TGF-beta(1). The contralateral common jugular vein was used as control.
Histological examination showed a great amount of vascular smooth muscle cells (VSMCs) in the tunica intima and tunica media of the vein graft since the 7 th day after the transplantation. mRNA expression of Egr-1, PDGF-B, and TGF-beta(1) was not found in the normal veins. The expression of Egr-1 mRNA in the vein graft showed a biphasic manner: increased remarkably 1 h after the transplantation, decreased during the period 6 h approximately 3 d after, re-increased 7 d after, and peaked 4 weeks after. The mRNA expression of PDGF-B appeared 6 h after, and peaked 2 weeks after, and began to decrease since the 4 th week. The mRNA expression of TGF-beta(1) increased 6 h after, peaked 7d after, and began to decrease 2 weeks after. The protein expression of Egr-1 appeared 2 h after, and peaked 4 weeks after; the protein expression of PDGF-B appeared 6 h after and peaked 4 weeks after; and the protein expression of TGF-beta(1). Appeared 24 h after and peaked 2 weeks after. Immunohistochemistry showed that Egr-1 protein expression was mainly in the VSMCs and monocytes/macrophages in the tunica media in the early stage after transplantation, and peaked 4 weeks later with a positive cell rate of 40% +/- 9%; in the early stage after transplantation PDGF-B protein expression was mainly in the VSMCs in the tunica media, and peaked 4 weeks after with a positive cell rate of 45% +/- 4%; the TGF-beta(1) protein expression peaked 2 weeks after with a positive cell rate of 41% +/- 7%; and 4 weeks after transplantation the protein expressions of Egr-1, PDGF-B, and TGF-beta(1) were all mainly in the VSMCs in the newly-grown tunica intima.
The IH of vein graft is affinitive with the expression of Egr-1, PDGF-B, and TGF-beta(1). The activation and expression of Egr-1, PDGF-B, and TGF-beta(1) depend on Egr-1 and may contribute to the high expression of Egr1 via a feedback mechanism.
研究早期生长反应基因-1（Egr-1）及其相关基因：血小板衍生生长因子-B（PDGF-B）基因和转化生长因子-β(1)（TGF-β(1)）基因在自体静脉移植物中的表达情况，以及这些基因的表达与内膜增生（IH）的关系。
将90只Wistar大鼠右侧颈总静脉的一段移植到同一动物的肾下腹主动脉，建立自体静脉移植物模型。于术后1、2、6和24小时、3天和7天、2、4和6周采集静脉样本进行组织学检查。采用原位杂交和RT-OCR检测Egr-1、PDGF-B和TGF-β(1)的mRNA表达。采用蛋白质印迹法和免疫组织化学法检测Egr-1、PDGF-B和TGF-β(1)的蛋白质表达。以对侧颈总静脉作为对照。
组织学检查显示，移植后第7天起，静脉移植物的内膜和中膜中有大量血管平滑肌细胞（VSMC）。正常静脉中未发现Egr-1、PDGF-B和TGF-β(1)的mRNA表达。静脉移植物中Egr-1 mRNA的表达呈双相性：移植后1小时显著升高，6小时至3天期间下降，7天后再次升高，4周后达到峰值。PDGF-B的mRNA表达在6小时后出现，2周后达到峰值，第4周起开始下降。TGF-β(1)的mRNA表达在6小时后升高，7天后达到峰值，2周后开始下降。Egr-1的蛋白质表达在2小时后出现，4周后达到峰值；PDGF-B的蛋白质表达在6小时后出现，4周后达到峰值；TGF-β(1)的蛋白质表达在24小时后出现，2周后达到峰值。免疫组织化学显示，移植后早期Egr-1蛋白表达主要位于中膜的VSMC和单核细胞/巨噬细胞中，4周后达到峰值，阳性细胞率为40%±9%；移植后早期PDGF-B蛋白表达主要位于中膜的VSMC中，4周后达到峰值，阳性细胞率为45%±4%；TGF-β(1)蛋白表达2周后达到峰值，阳性细胞率为41%±7%；移植后4周，Egr-1、PDGF-B和TGF-β(1)的蛋白表达均主要位于新生内膜的VSMC中。
静脉移植物的IH与Egr-1、PDGF-B和TGF-β(1)的表达有关。Egr-1、PDGF-B和TGF-β(1)的激活和表达依赖于Egr-1，并可能通过反馈机制促进Egr1的高表达。
