Abstract: Objective To investigate the effect and mechanism of CXC chemokine ligand 12 (CXCL12) on oxidized low density lipoprotein (ox-LDL)-induced foaming and apoptosis of macrophages. Methods RAW264.7 was incubated with 60 mg/L of ox-LDL to induce foaming of macrophages, which was recorded as ox-LDL group, and to compare with the control without ox-LDL; si-con and si-CXCL12 were transfected to RAW264.7 cells and thenincubated with ox-LDL at 60 mg/L as ox-LDL+si-con group and ox-LDL+si-CXCL12 group, respectively. Oil Red O staining was used to detect cellular foaming; Western blot was used to detect ABCA-1, SRB-1, cleaved caspase-3, cleaved caspase-9, CXCL12, p38 mitogen-activated protein kinase (p38MAPK), and phosphorylated p38MAPK (p-p38MAPK) protein expression; flow cytometry is used to detect apoptosis; CXCL12 mRNA expression was measured by real-time fluorescence quantitative PCR(RT-qPCR). Results The size of ox-LDL-treated macrophages increased, the shape became round, and a large number of red lipid droplets were found in the cytoplasm; the expression of ABCA-1 and SRB-1 and cleaved caspase-3 as well as cleaved caspase-9 were all significantly increased; the apoptosis rate and the expression of CXCL12 and p-p38MAPK were significantly increased(P＜0.05). Silencing CXCL12, no red-stained lipid droplets were found in most cells, only a few cells had partial lipid droplets, the expressions of ABCA-1 and SRB-1 were significantly reduced, and the expression of cleaved caspase-3 and cleaved caspase-9, apoptosis rate and the expression of p-p38MAPK significantly reduced(P＜0.05). Conclusions Silencing CXCL12 inhibits ox-LDL-induced foaming and apoptosis of mouse macrophage cell line RAW264.7, which may be related to the p38MAPK signaling pathway.

Key words: CXC chemokine ligand 12, oxidized low density lipoprotein, macrophage foaming, apoptosis