The Enhanced Effect Of SDF-1α On Monocytes/endothelium Cells Adhesion By The Activation Of LFA-1

Chemokine SDF-1αand its receptor CXCR4 plays an important role in embryogenesis, migration and homing of hematopoietic stem cells,tumor metastasis ,immune,inflammation,mediation HIV infection and so on. Close attention has been paid to the role of SDF-1α/CXCR4 in atherosclerosis owing to SDF-1αhigh expression in atherosclerosis plaque from recent study.Our previous work show SDF-1αhas pro-adhesive effect, in other words, it can enhance adhesion of THP-1 monocytes to endothelium cells or VSMCs, but it is unclear what is the mechanisms of SDF-1αpro-adhesive effect. So the aim of the present study was to probe into the mechanisms.Objective To investigate the effect of ox-LDL on the expression of SDF-1αand ICAM-1 in endothelium, the role of SDF-1αin the expression and distributing of LFA-1 in THP-1 cells, the influence of SDF-1α, SDF-1αantibody and LFA-1 antibody on monocytes/endothelium cells adhesion.Methods Cultured endothelial cells(ECV-304) were incubated ox-LDL with different concentrations(0-125μg/ml) for the same time(48h) and with the same concentration(25μg/ml) for different time course(0-48h ). monocytes (THP-1) were incubated SDF-1αwith the same concentration(100ng/ml) for different time course(0 and 30min ). SDF-1α, ICAM-1 and LFA-1mRNA and protein expressions were detected by RT-PCR and Western blotting respectively. LFA-1 re-distributing was observed by immunofluorescence in THP-1 pretreated with 100ng/ml SDF-1αfor 30m. Endothelium pretreated with 25μg/ml ox-LDL for 48h were incubated with THP-1 cells and with or without SDF-1αantibody or LFA-1 antibody to observe cells adhesion. Endothelium pretreated with different concentrations SDF-1αwere incubated with THP-1 cells and with or without LFA-1 antibody to observe cells adhesion.Results SDF-1αwas hardly expressed in normal endothelium but was up-regulated by ox-LDL in a dose-dependent manner within 0-125μg/ml for 48h and in a time-dependent manner within 0-48h, peaked at 25μg/ml for 48h; ICAM-1 was constitutionally expressed in endothelium and was up-regulated by ox-LDL in a concentration-dependennt manner within 0-125μg/ml for 48h, peaked at 25μg/ml for 48h. LFA-1was constitutionally expressed in THP-1 cells. Though LFA-1 expression was unchanged, the activation of LFA-1 was happened in THP-1 cells pretreated with 100ng/ml SDF-1αfor 30m. THP-1/ ECV-304 adhesion was enhanced by ox-LDL in a concentration-dependent manner and peaked in 25μg/ml ox-LDL group, but this effect was obviously inhibited by the antibody to SDF-1αor LFA-1. SDF-1αcould enhance THP-1/ECV-304 adhesion, but it was obviously inhibited by the LFA-1 antibody.Conclusions Ox-LDL up-regulating SDF-1αand ICAM-1 expression in endothelium. SDF-1αunchanging LFA-1 expression but activating it in THP-1 cells. SDF-1αenhances monocyte s/endothelium cells adhesion by LFA-1 activation.