Impinging Flow Induces Kaiso-mediated Inflammation Of Vascular Endothelial Cells

Objective:The cause of intracranial aneurysms is still not clear.At present,it is thought that the endothelial cell damage,vascular inflammation,and wall remodeling caused by hemodynamic changes are the possible causes of the formation and rupture of aneurysms.This study investigated the effect of hemodynamics on the morphology of endothelial cells and the related mechanisms of endothelial cell injury by simulating the in vitro T-shaped flow system of hemodynamics at the bifurcation of the vessel and acting on human umbilical vein endothelial cells(HUVEC).Methods:HUVEC were cultured in vitro and were transfected with RNAi kaiso recombinant lentivirus.Both cells were seeded on sterile slides and the slides were placed in a T-shaped flow system.Impulse flow at a flow rate of 500 ml/min was loaded for 0,3,6,and 12 hours.Western Blot,immunocytochemistry and co-immunoprecipitation were used to detect the changes of cell morphology and kaiso-related protein expression.Result:(1)Morphological changes of normal HUVEC under impinging flow field:a.Ordinary inverted microscope:the cells in region 1 are basically unchanged;the cell density in region 2 is significantly decreased,the cells are separated,the space between cells is enlarged,and a axis-like elongation parallel to the fluid direction;cells in region 3 Increased density;b.The result of immunocytochemistry showed that under the impact of flow field,the cytoskeleton of region 2 appeared parallel to the direction of the impact flow,and there was no obvious change in the region 1 and the region 3.(2)Western Blot of normal HUVEC showed that the expression of mmp-2,mmp-9 and kaiso in HUVEC increased,and the expression of timp-2 and timp-1 decreased with the prolongation of the impact time,which was statistically significant(P<0.05).There was no significant change in expression of p120(P>0.05).The result of co-immunoprecipitation showed that the binding of kaiso and p120 in normal HUVEC increased significantly with the prolongation of the impact time.(3)Western Blot of HUVEC transfected with RNAi kaiso lentivirus showed that the expression of mmp-2、mmp-9 and timp-1 was decreased.The difference was statistically significant(P<0.05).The changes of timp-2 and p120 expression were not significant(P>0.05).Conclusion:Under the impact of flow field,the cell density in the high WSS and high WSSG regions decreased significantly,the cells were separated,the cell gaps were enlarged,and the axis-like elongation paralleled to the fluid direction,and the binding of p120 and kaiso increased.Those increase the expression of inflammatory factors mmp-2,mmp-9,causing inflammation of the vascular wall and damage of endothelial cell,promoting the formation of intracranial aneurysms.