Objective       To investigate the relationship of the changes of cell adhesion with the expression of angiotensin-converting enzyme 2 (ACE2) in vascular endothelial cells after LPS injury

and to determine the antagonism of ACE2 on increasing adhesion caused by vascular endothelial injury.        Methods       After human umbilical vein endothelial cells (HUVECs) were injured by LPS at different concentrations (0

10

100 and 1 000 ng/mL)

the cells adhesion was observed through human acute monocytic leukemia THP-1 cells adhesion experiment. The HUVECs were assigned into 4 groups

including untreated blank control cells

injured cells (induced by 1 000 ng/mL LPS for 6 h)

injured cells with pretreatment of 10 μmol/L losartan potassium

and blank control cells with pretreatment of 10 μmol/L A779 for 0.5 h. Expression of ACE2 at protein and mRNA levels was detected by Western blotting and RT-PCR respectively

and the contents of AngⅡ

Ang1-7 and ICAM-1 in the cultural supernatants were measured by ELISA.       Results       THP-1 adhered HUVEC showed green fluorescence

and the number of adhesion cells was increased significantly in a dose- and time-dependent manner (P0.01). Compared with blank control group

Western blot results showed that the protein expression of ACE2 was reduced significantly in the injured cells by (37.33±3.50)% (P0.01)

RT-PCR results showed that its mRNA expression was decreased obviously by (26.31±2.19)% (P0.01). And ELISA results showed that the content of Ang1-7 was decreased significantly (P0.05)

but those of AngⅡ and ICAM-1 increased significantly in the injured cells than the blank control group (P0.01). The content of ICAM-1was obviously lower in the losartan potassium pretreated cells than the injured cells (P0.01)

and higher in the A779 pretreated blank cells than the blank control (P0.05).       Conclusion       LPS treatment induces cell adhesion in HUVECs

which is closely associated with down-regulation of ACE2. Our results indicate that the molecule exerts anti-adhesion effect in the process.