Abstract: Objective To investigate the relationship between proprotein convertase subtilisin/kexin type 9 (PCSK9) and inflammatory factor expression in apoptosis of human umbilical vein endothelial cells (HUVECs) induced by oxidized low density lipoprotein(ox-LDL).Methods HUVECs were incubated with ox-LDL for different times (0 h,12 h,24 h,36 h,48 h). The mRNA and protein expression of PCSK9, inter leukin 6(IL-6), monocyte chemotactic protein-1(MCP-1), matrix metalloprotein-9(MMP-9), C-reactive protein (CRP) and the nucler displacement of nucler factor-kappa B (NF-κB) were detected. The siRNA for PCSK9 was designed and synthesized,then was transfected into HUVECs by Lipofectamine 2000. After transfection for 6 h, cells were treated with ox-LDL for 24 h, the mRNA and protein expression of PCSK9, IL-6, MCP-1, MMP-9, CRP and the nucler displacement of NF-κB were detected.Results With the increase of ox-LDL processing time, the mRNA expressions of PCSK9, IL-6, MCP-1, MMP-9 and CRP were significantly higher, and the nucler displacement of NF-κB was significantly increased, especially for 24 h incubation, and the subsequent expression and the nucler displacement were gradually decreased (P<0.05). The protein concentration of IL-6, MCP-1, CRP and MMP-9 in cell culture supernatant increased gradually over time, and reached the peak at 48 h. Compared with the 0 h group, the 48 h group increased most obviously (P<0.01). The mRNA and protein expressions of PCSK9, IL-6, MCP-1, MMP-9, CRP and the nucler displacement of NF-κB in siRNA group were significantly lower than those in negative transfection group (P<0.01).Conclusion PCSK9 siRNA can inhibit inflammation factor expression in apoptosis of HUVECs induced by ox-LDL. And PCSK9 may be involved in the regulation of inflammation.