Effect of laminar shear stress on leukocyte endothelial adhesion under hyperlipemia and its mechanism

LI Yanling; HE Xiaohong; ZHANG Yan; ZHONG Tingting; DONG Yugang; MA Hong; ZHENG Zhensheng

doi:10.3969/j.issn.1002-266X.2016.16.005

Abstract：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.