Cowan K N, Jones P L, Rabinovitch M
Division of Cardiovascular Research/Department of Laboratory Medicine and Pathobiology, Hospital for Sick Children/University of Toronto, Ontario, Canada.
Circ Res. 1999 May 28;84(10):1223-33. doi: 10.1161/01.res.84.10.1223.
Increased elastase activity and deposition of the matrix glycoprotein tenascin-C (TN), codistributing with proliferating smooth muscle cells (SMCs), are features of pulmonary vascular disease. In pulmonary artery (PA) SMC cultures, TN is regulated by matrix metalloproteinases (MMPs) and mechanical stress. On attached collagen gels, MMPs upregulate TN, leading to SMC proliferation, whereas on floating collagen, reduced MMPs suppress TN and induce SMC apoptosis. We now investigate the response of SMCs in the whole vessel by comparing attached and floating conditions using either normal PAs derived from juvenile pigs or normal or hypertrophied rat PAs that were embedded in collagen gels for 8 days. Normal porcine PAs in attached collagen gels were characterized by increasing activity of MMP-2 and MMP-9 assessed by zymography and TN deposition detected by Western immunoblotting and densitometric analysis of immunoreactivity. PAs on floating collagen showed reduced activity of both MMPs and deposition of TN. Tenascin-rich foci were associated with proliferating cell nuclear antigen immunoreactivity, and TN-poor areas with apoptosis, by terminal deoxynucleotidyl transferase-mediated nick end labeling assay, but no difference in wall thickness was observed. Although normal rat PAs were similar to piglet vessels, hypertrophied rat PAs showed an amplified response. Increased elastase, MMP-2, TN, and elastin deposition, as well as SMC proliferating cell nuclear antigen positivity, correlated with progressive medial thickening on attached collagen, whereas reduced MMP-2, elastase, TN, and induction of SMC apoptosis accompanied regression of the thickened media on floating collagen. In showing that hypertrophied SMCs in the intact vessel can be made to apoptose and that resorption of extracellular matrix can be achieved by inhibition of elastase and MMPs, our study suggests novel strategies to reverse vascular disease.
弹性蛋白酶活性增加以及基质糖蛋白腱生蛋白-C（TN）沉积，与增殖的平滑肌细胞（SMC）共分布，是肺血管疾病的特征。在肺动脉（PA）平滑肌细胞培养中，TN受基质金属蛋白酶（MMP）和机械应力调节。在附着的胶原凝胶上，MMP上调TN，导致SMC增殖，而在漂浮的胶原上，MMP减少抑制TN并诱导SMC凋亡。我们现在通过比较附着和漂浮条件来研究完整血管中SMC的反应，使用来自幼年猪的正常PA或嵌入胶原凝胶8天的正常或肥大的大鼠PA。附着的胶原凝胶中的正常猪PA的特征是通过酶谱法评估的MMP-2和MMP-9活性增加，以及通过Western免疫印迹和免疫反应性光密度分析检测到的TN沉积。漂浮胶原上的PA显示MMPs活性和TN沉积均减少。通过末端脱氧核苷酸转移酶介导的缺口末端标记法，富含腱生蛋白的病灶与增殖细胞核抗原免疫反应性相关，而TN含量低的区域与细胞凋亡相关，但未观察到壁厚差异。尽管正常大鼠PA与仔猪血管相似，但肥大的大鼠PA显示出放大的反应。弹性蛋白酶、MMP-2、TN和弹性蛋白沉积增加，以及SMC增殖细胞核抗原阳性，与附着胶原上的进行性中膜增厚相关，而MMP-2、弹性蛋白酶、TN减少以及SMC凋亡诱导伴随着漂浮胶原上增厚中膜的消退。我们的研究表明，完整血管中肥大的SMC可以诱导凋亡，并且通过抑制弹性蛋白酶和MMP可以实现细胞外基质的吸收，这提示了逆转血管疾病的新策略。
