Department of Pharmacology and Toxicology, Institute of Biomedicine, University of Oulu, Biocenter Oulu, Oulu, Finland.
Atherosclerosis. 2012 Jan;220(1):66-71. doi: 10.1016/j.atherosclerosis.2011.10.003. Epub 2011 Oct 12.
Active involvement of extracellular matrix (ECM) and its composition regulating factors may have a central role in the pathogenesis of calcific aortic valve disease (CAVD). Thrombospondins (TSPs) are highly conserved matricellular proteins regulating inflammation, angiogenesis and ECM remodeling. These processes are strongly associated with progression of aortic valve stenosis (AS). However, the expression of TSPs in CAVD is not known.
We characterized the expression of TSPs 1-4 in human aortic valves by real-time quantitative reverse transcriptase polymerase chain reaction and immunohistochemistry. Control valves (n=8), thickened and stiffened fibro(sclero)tic valves (n=8), and calcified AS valves (n=24) were compared. Furthermore, potential factors regulating TSP-2 expression was studied by western blotting and gel mobility shift assay in another set of control (n=10) and AS (n=20) valves.
TSP-2 mRNA levels were increased 4.9-fold (P=0.037) and 4.8-fold (P=0.001) in fibro(sclero)tic and stenotic valves, respectively, whereas the expression of other TSPs did not change significantly. All TSPs 1-4 were detected from aortic valves by immunohistochemistry. Positive TSP-2 immunostaining was seen in the valvular myofibroblasts and patchily in endothelial cells. Semiquantitative analysis of TSP-2 staining indicated increased immunoreactivity for TSP-2 in neo vessels of fibro(sclero)tic and calcified aortic valves. Finally, when compared to controls, AS was associated with significant down regulation of Akt-pathway and diminished binding activity of nuclear factor-κB (NF-κB).
We report for the first time that TSPs 1-4 are expressed in human aortic valves. CAVD is characterized by myofibroblastic proliferation and neovascularization associated upregulation of TSP-2 expression, as well as inactivation of Akt and NF-κB.
细胞外基质（ECM）及其组成调节因子的积极参与可能在钙化性主动脉瓣疾病（CAVD）的发病机制中起核心作用。血小板反应蛋白（TSPs）是高度保守的基质细胞蛋白，可调节炎症、血管生成和 ECM 重塑。这些过程与主动脉瓣狭窄（AS）的进展密切相关。然而，CAVD 中 TSPs 的表达情况尚不清楚。
我们通过实时定量逆转录聚合酶链反应和免疫组织化学方法来描述 TSPs 1-4 在人主动脉瓣中的表达。比较了正常瓣膜（n=8）、增厚和硬化的纤维（硬化）瓣膜（n=8）和钙化的 AS 瓣膜（n=24）。此外，通过 Western 印迹和凝胶迁移率变动分析，在另一组对照（n=10）和 AS（n=20）瓣膜中研究了调节 TSP-2 表达的潜在因素。
纤维化和狭窄瓣膜中 TSP-2mRNA 水平分别增加了 4.9 倍（P=0.037）和 4.8 倍（P=0.001），而其他 TSPs 的表达没有明显变化。免疫组织化学检测到所有 TSPs 1-4 均存在于主动脉瓣中。TSP-2 免疫染色阳性见于瓣膜成纤维细胞中，内皮细胞呈斑片状阳性。TSP-2 染色的半定量分析表明，纤维化和钙化主动脉瓣中的新生血管中 TSP-2 免疫反应性增强。最后，与对照组相比，AS 与 Akt 通路的显著下调以及核因子-κB（NF-κB）结合活性的降低有关。
我们首次报道 TSPs 1-4 存在于人主动脉瓣中。CAVD 的特征是成纤维细胞增殖和新生血管形成，TSP-2 表达上调，以及 Akt 和 NF-κB 失活。
