Effects Of Porphyromonas Gingivalis On The Adhesion Activities And Biological Characteristics Of Vascular Endothelial Cells

Objective: Porphyromonas gingivalis(P.gingivalis),as a key periodontal pathogen,is considered as one of the factors contributing to atherosclerosis(AS).Our previous studies showed that P.gingivalis could enhance the expression of intercellular adhesion molecule-1(ICAM-1)and monocyte-endothelial cell adhesion through up-regulating the secretion of macrophage migration inhibitory factor(MIF)in vascular endothelial cells.Besides,both MIF’s receptors CD74 and CXCR4 could affect ICAM-1 expression and monocyte-endothelial cell adhesion.These results suggest that MIF may bind to CD74 or CXCR4 to transmit the intracellular signal of P.gingivalis enhancing the adhesion activity of vascular endothelial cells.The purpose of this study is to explore the interaction between CD74 and CXCR4 and MIF,and the effects of P.gingivalis and CXCR4 on the biological characteristics of vascular endothelial cells.Thereby to reveal the mechanism of P.gingivalis improving the cell adhesion activity of vascular endothelial cells,and to investigate the possible pathways of P.gingivalis influencing the occurrence of AS.Methods: Immunofluorescence staining was performed to detecte the localization of CD74 and CXCR4 on the surface of EA.hy926 cells infected by P.gingivalis.CXCR4-shRNA(CXCR4i)stable cell lines were constructed by plasmid transfection.The relationship among MIF,CD74 and CXCR4 in endothelial cells infected by P.gingivalis was confirmed by coimmunoprecipitation and pull-down assays.The effects of P.gingivalis and CXCR4 on the proliferation,cell cycle and apoptosis of EA.hy926 cells were investigated by CCK-8 and flow cytometry,respectively.Results: 1.Immunofluorescence staining showed that co-localization of CD74 and CXCR4 existed on the surface of EA.hy926 cells infected by P.gingivalis.2.Coimmunoprecipitation and pull-down assays confirmed that MIF regulated endothelial cell adhesion activity by binding to CD74/CXCR4 complex in EA.hy926 cells infected by P.gingivalis.3.P.gingivalis infection or CXCR4 silencing could inhibit the proliferation(P﹤0.05),block the cell cycle at G0-G1 phase(P﹤0.05),and promote the apoptosis of EA.hy926 cells(P﹤0.05).Conclusions: 1.P.gingivalis could up-regulate EA.hy926 cell adhesion activity through MIF-CD74/CXCR4 ligand-receptor complex pathway.MIF-CD74/CXCR4 complex plays an important role in P.gingivalis affecting AS formation.2.P.gingivalis may damage the integrity of vascular endothelial cells and inhibit the repair ability of vascular endothelial cells by inhibiting cell proliferation and promoting cell apoptosis,which may play a pathogenic role in the initiation of early cellular behavior in AS.3.After silencing CXCR4 reduced cell proliferation and increased apoptosis,suggesting that CXCR4 may play a protective role in endothelial cell regeneration and repair.