Ohtsuka A, Ando J, Korenaga R, Kamiya A, Toyama-Sorimachi N, Miyasaka M
Department of Cardiovascular Biomechanics, Faculty of Medicine, University of Tokyo, Japan.
Biochem Biophys Res Commun. 1993 May 28;193(1):303-10. doi: 10.1006/bbrc.1993.1624.
Adherence of leukocytes to vascular endothelial cells (ECs) is known to be sensitive both to blood flow and adhesive proteins on EC surface. To elucidate the effect of blood flow on the surface expression of adhesive proteins, cultured ECs derived from mouse lymph nodes were exposed to different levels of wall shear stress in a flow-loading chamber, and changes in the expression of vascular adhesion molecule-1 (VCAM-1) and CD44 were evaluated by immunostaining with monoclonal antibodies and flow cytometry. Both proteins were expressed on non-activated cultured ECs. When exposed to flow with shear stress of 1.5 dynes/cm2 for 24 hr, VCAM-1 nearly disappeared on fluorescence micrographs, while CD44 showed no change. Flow cytometric analysis showed that the mean channel fluorescence of VCAM-1 was decreased about 75% by application of flow for 24 hr (p < 0.001), but that of CD44 remained unchanged. VCAM-1 expression began to decrease around 1 hr after the initiation of flow and became markedly reduced with time, reaching a minimum after 24 hr. When the cells subjected to flow for 24 hr were returned to stationary state, the reduced VCAM-1 expression was almost completely restored in 72 hr, indicating that the change was reversible. The magnitude of the reduction of VCAM-1 expression was also dependent on the intensity of the wall shear stress applied, ranging from 0 to 7.2 dynes/cm2. These results, demonstrating an explicit down-regulating effect of flow on VCAM-1 expression of cultured ECs, suggested preferential adhesion of leukocytes to ECs at low shear regions at the vascular wall.
已知白细胞与血管内皮细胞（ECs）的黏附对血流和ECs表面的黏附蛋白均敏感。为阐明血流对黏附蛋白表面表达的影响，将从小鼠淋巴结分离培养的ECs置于流动加载室中，使其暴露于不同水平的壁面剪切应力下，并用单克隆抗体免疫染色和流式细胞术评估血管细胞黏附分子-1（VCAM-1）和CD44表达的变化。两种蛋白均在未激活的培养ECs上表达。当暴露于剪切应力为1.5达因/平方厘米的血流中24小时后，荧光显微镜下VCAM-1几乎消失，而CD44无变化。流式细胞术分析显示，施加24小时血流后，VCAM-1的平均通道荧光降低约75%（p<0.001），但CD44的平均通道荧光保持不变。VCAM-1表达在血流开始后约1小时开始下降，并随时间显著降低，24小时后降至最低。当经受24小时血流的细胞恢复到静止状态时，降低的VCAM-1表达在72小时内几乎完全恢复，表明这种变化是可逆的。VCAM-1表达降低的幅度也取决于所施加壁面剪切应力的强度，范围为0至7.2达因/平方厘米。这些结果表明血流对培养的ECs的VCAM-1表达具有明显的下调作用，提示白细胞在血管壁低剪切区域优先与ECs黏附。
