Dattilo J B, Dattilo M P, Yager D R, Makhoul R G
Department of Surgery, Medical College of Virginia/Virginia Commonwealth University, Richmond 23298-0108, USA.
Ann Vasc Surg. 1998 Mar;12(2):168-73. doi: 10.1007/s100169900136.
The success rate of vascular bypass procedures is limited by the development of intimal hyperplasia (IH). Hypercholesterolemia has been shown to accelerate IH in both arteries and experimental vein grafts; however the mechanism remains uncertain. Hyaluronic acid synthase (HAS-1) is a transmembrane enzyme responsible for the formation of hyaluronan; an important constituent of extracellular matrix (ECM). The integrin receptor for hyaluronan is CD-44. Both CD-44 and HAS-1 have been studied in the development of ECM of wounds but have yet to be examined in the ECM of IH within vein grafts. The purpose of this study was to determine if the expression of CD-44 and HAS-1 is increased during the early stages of IH and how cholesterol supplementation affects these genes. Forty white male New Zealand rabbits were divided into two groups: cholesterol supplemented (1% cholesterol chow) and noncholesterol supplemented. Each set of 20 rabbits was then divided into four additional groups (n = 5); a nonoperative group (control) and three operative groups that underwent a right interposition carotid bypass using jugular vein. Grafts were harvested at 3, 7, and 21 days after surgery for molecular studies and histology. Ribonuclease protection assays were performed using 32P-labeled riboprobes for HAS-1, CD-44, and 18s rRNA. Densitometric analysis is expressed as a ratio (riboprobe/rRNA). Cholesterol levels differed significantly between cholesterol supplemented and nonsupplemented groups (1419 +/- 130 mg/dl and 48 +/- 12 mg/dl) (p < 0.01). There was a significant increase in the expression of HAS-1 and CD-44 in the vein grafts compared to normal jugular vein. Cholesterol supplementation caused a further increase in CD-44 gene expression versus nonsupplemented vein grafts. These data demonstrate a role for CD-44 and HAS-1 transcription in vein graft intimal hyperplasia, which is further altered by cholesterol supplementation. Lastly, these results could explain differences seen in the development of IH with hypercholesterolemia and ultimately provide for improved therapies in alleviating this process.
血管搭桥手术的成功率受到内膜增生（IH）的限制。高胆固醇血症已被证明会加速动脉和实验性静脉移植物中的内膜增生；然而，其机制仍不确定。透明质酸合酶（HAS-1）是一种跨膜酶，负责透明质酸的形成；透明质酸是细胞外基质（ECM）的重要组成部分。透明质酸的整合素受体是CD-44。CD-44和HAS-1都已在伤口的细胞外基质形成过程中进行了研究，但尚未在静脉移植物的内膜增生的细胞外基质中进行研究。本研究的目的是确定在IH的早期阶段CD-44和HAS-1的表达是否增加，以及胆固醇补充如何影响这些基因。40只雄性新西兰白兔被分为两组：补充胆固醇组（1%胆固醇饲料）和未补充胆固醇组。然后，每组20只兔子再分为另外四组（n = 5）；一个非手术组（对照组）和三个手术组，这些手术组使用颈静脉进行右侧颈总动脉间置搭桥术。在术后3天、7天和21天采集移植物用于分子研究和组织学检查。使用针对HAS-1、CD-44和18S rRNA的32P标记的核糖探针进行核糖核酸酶保护测定。密度分析表示为一个比值（核糖探针/rRNA）。补充胆固醇组和未补充胆固醇组之间的胆固醇水平差异显著（分别为1419 +/- 130 mg/dl和48 +/- 12 mg/dl）（p < 0.01）。与正常颈静脉相比，静脉移植物中HAS-1和CD-44的表达显著增加。与未补充胆固醇的静脉移植物相比，补充胆固醇导致CD-44基因表达进一步增加。这些数据证明了CD-44和HAS-1转录在静脉移植物内膜增生中的作用，胆固醇补充会进一步改变这种作用。最后，这些结果可以解释高胆固醇血症在内膜增生发展过程中所观察到的差异，并最终为缓解这一过程提供改进的治疗方法。
