Objective To investigate the effect of laminar shear stress on leukocyte-endothelial adhesion in the envi-ronment of hyperlipemia and its mechanism .Methods We used oxidized low density lipoprotein ( OX-LDL) to make the environment of hyperlipemia then induced the injuries of human umbilical vein endothelial cells (HUVECs).The laminar shear stress at 0, 5 and 25 dyne/cm2 was used to intervene HUVECs for 4 h which was taken as the 0, 5 and 25 dyne/cm2 groups.U937 cells were applied in the leukocyte-endothelial adhesion experiment , in which the number of U937 cells ad-herent to HUVECs was counted .Immunofluorescent confocal laser scanning and flow cytometry were respectively used to analyze the fluorescence signal intensity and positive rate of integrin β1 in HUVECs.Results The number of leukocyte-en-dothelial adhesion cells was gradually decreased from 0 dyne/cm2, 5 dyne/cm2 and to 25 dyne/cm2 groups (all P<0.05). The fluorescence signal intensity of integrin β1 in cytomembrane weakened from 0 dyne/cm2 , 5 dyne/cm2 and to 25 dyne/cm2 .The positive rates of integrin β1 in 0 dyne/cm2 group, 5 dyne/cm2 group and 25 dyne/cm2 group were 98.98 ± 0.36%, 88.58 ±3.34%and 81.28 ±5.19%, respectively, and the positive rate of integrin β1 in 0 dyne/cm2 group was significantly higher than that in 25 dyne/cm2 group (P<0.05), while there was no statistical difference between 0 dyne/cm2 and 5 dyne/cm2 groups, neither between 5 dyne/cm2 and 25 dyne/cm2 groups (all P>0.05).Conclusion Increas-ing laminar shear stress to a relatively high level within proper range could inhibit leukocyte -endothelial adhesion in the en-vironment of hyperlipemia , and its mechanisms may be related to the down-regulation of integrinβ1 expression.%目的：探讨层流剪切应力对高脂环境下白细胞-内皮细胞黏附的影响及其机制。方法以氧化型低密度脂蛋白造成高脂环境，诱导人脐静脉内皮细胞（HUVECs）损伤，分别以0、5、25 dyne／cm2层流剪切应力对损伤后的HUVECs干预4 h（分别记为0、5、25 dyne／cm2组）。采用人白血病淋巴瘤细胞株U937行白细胞-内皮细胞黏附试验，计算每100个HUVECs上黏附的U937细胞数；采用激光扫描共聚焦显微镜观察HUVECs细胞膜上的β1整合素抗体荧光信号强度，流式细胞术检测β1整合素阳性率。结果0 dyne／cm2组、5 dyne／cm2组和25 dyne／cm2组黏附的细胞数量依次降低（P均＜0．05），细胞膜上的β1整合素抗体荧光信号强度逐渐减弱，β1整合素阳性率分别为98．98％±0．36％、88．58％±3．34％、81．28％±5．19％；0 dyne／cm2组β1整合素阳性率明显高于25 dyne／cm2组（P＜0．05），0 dyne／cm2组与5 dyne／cm2组比较、5 dyne／cm2组与25 dyne／cm2组比较均无统计学差异（P均＞0．05）。结论在一定范围内适当提高层流剪切应力能够降低高脂环境下内皮细胞上黏附的白细胞数量，机制可能与降低内皮细胞膜β1整合素表达有关。
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