Aim To investigate whether the expression of groupⅣcytosolic phospholipase A2(cytosolic phospholipase A2,cPLA2),groupⅤsecretory phospholipase A2(sPLA2-Ⅴ) and groupⅩsecretory phospholipase A2 (sPLA2-Ⅹ) could be regulated by oxidized low density lipoprotein(ox-LDL) of different oxidation levels in the mouse macrophage cell line RAW264.7 cells,and to explore the inflammatory mechanisms of the interactions between ox-LDL and macrophages in the process of promoting atherosclerosis.Methods 3 types of ox-LDL(minimally modified low density lipoprotein or MM-LDL,lightly ox-LDL or ox_(4h)-LDL,heavily ox-LDL or ox_(48h)-LDL) were prepared by different oxidation ways.3 types of ox-LDL were used to incubate with RAW264.7 cells for 4 h and 8 h,then the cell lysate and cell culture supernatant were collected.The mRNA expression and protein expression of cPLA2,sPLA2-Ⅴand sPLA2-Ⅹwere determined respectively by reverse transcription polymerase chain reaction(RT-PCR) and Western blotting analysis. Results The mRNA expression and protein expression of sPLA2-Ⅴand sPLA2-Ⅹwere undetectable in untreated RAW264.7 cell.Compared with the PBS control group and the LDL group,the mRNA expression of cPLA2 was not affected by all types of ox-LDL(P>0.05).But the mRNA expression and protein expression of sPLA2-Ⅴand sPLA2-Ⅹwere significantly enhanced by the stimulation of MM-LDL and ox_(4h)-LDL in RAW264.7 cell(P<0.05),while ox_(48h)-LDL had a slight ability to induce the expression of sPLA2-Ⅴand sPLA2-Ⅹ(P<0.05).However,PBS control group and native LDL failed to induce the expression of sPLA2-Ⅴand sPLA2-Ⅹ.Conclusion The exposure of ox-LDL to RAW264.7 cells did not affect the mRNA expression of cPLA2,but could significantly induce RAW264.7 cells to express sPLA2-Ⅴand sPLA2-Ⅹ.Two types of mildly oxidized LDL(MM-LDL and ox_(4h)-LDL)-induced expression of sPLA2-Ⅴand sPLA2-Ⅹwas stronger than that of heavily oxidized LDL(ox_(48h)-LDL),indicating that mildly oxidized LDL was capable of inducing a strong inflammatory response on macrophages.