Mechanisms of morphological and functional changes of endothelial cells in atherogesesis.

1.通过对内皮细胞凋亡抑制蛋白-2（human inhibitor of apoptosis protein-2，HIAP-2）表达的研究，探讨稳态层流切应力抗动脉粥样硬化的作用机制。HIAP-2在切应力诱导的ECs中呈剂量依赖性和时间依赖性。HIAP-2表达也在体内鉴定。切应力介导的EC凋亡的抑制与caspase-3活性的抑制有关。转染Smac，一种通过结合HIAPs并去除其抑制活性的caspase激活剂，降低了切应力对caspase-3活性的抑制作用。这些数据表明，剪切应力通过HIAP-2的增量对caspase-3的负调节来防止EC凋亡。2.层流切应力可完全阻断内皮细胞分泌MMP 2，但细胞内MMP 2蛋白和mRNA表达水平无明显变化。为了阐明这一机制，我们分析了MMP-2的细胞内运输，使用融合的MMP-2标记的GFP。B 关于我们 在层流剪切力作用下，MMP-2/GFP颗粒体积增大，并被转运到细胞膜上，但不分泌。我们的数据表明，层流剪切应力有助于EC粘附在基质上通过调节IV型胶原代谢。3.为了分析动脉粥样硬化的初始事件，我们建立了一种改进的正面方法，使我们能够获得包括动脉粥样硬化起始处的主动脉分叉口在内的整个内皮表面的清晰图像。SD大鼠主动脉分支区增殖的内皮细胞和粘附于内皮细胞上的巨噬细胞数量分别是非分支区的2倍和3倍。结论：层流切应力通过调控内皮细胞的死亡、生长、粘附及胶原代谢，抑制单核细胞粘附，从而稳定内皮细胞，可能有助于血管内抗动脉粥样硬化微环境的形成。少

1.To disclose the anti-atherosclerotic mechanisms of steady laminar shear stress, we analyzed the expression of human inhibitor of apoptosis protein-2(HIAP-2) in endothelial cells(ECs). HIAP-2 was dose-dependently and time-dependently induced in ECs by shear stress. HIAP-2 expression also identified in vivo. Shear stress-mediated inhibition of EC apoptosis was associated with inhibition of caspase-3 activity. Transfection of Smac, a caspase activator by binding HIAPs and removing their inhibitory activity, reduced the suppression effect of shear stress on caspase-3 activity. These data suggest that shear stress prevents EC apoptosis via negative regulation of caspase-3 by increments of HIAP-2. 2.The MMP2 secretion from ECs into medium was interrupted completely by laminar shear stress, although level of this intracellular protein and mRNA expression of MMP2 were unchanged. To clarify this mechanism, we analyzed intracellular transportation of MMP-2, using fused MMP-2 tagged with GFP. B … More y laminar shear stress, MMP-2/GFP granules increased their size and transported into cell membrane without secretion. Our data suggest that laminar shear stress contribute to EC adhesion on matrix through the regulation of collagen type IV metabolism. 3.To analyze a initial events of atherosclerosis, in vivo, we established a modified en face method that enabled us to obtain clear images of the entire surface of endothelium including a bifurcation orifices of aorta, where atherosclerosis initiates. A number of proliferating ECs and macrophages adhered on ECs, stained with specific antibodies, at the branching area of aorta from SD rats were about 2 and 3 times higher than that of non-branching area, respectively. In conclusion, stabilization of ECs through the regulation of cell death, cell growth, EC adhesion on matrix with control of collagen metabolism and inhibition of monocyte adhesion on ECs by the laminar shear stress may contribute to the formation of the anti-atherosclerotic microenvironment in vessels. Less