[The oxLDL/β2GPI/anti-β2GPI antibody complex promotes A7r5 chemotaxis, migration and lipid accumulation]

Objective To explore the effect of the oxidized low-density lipoprotein/β2 -glycoprotein I/β2 glycoprotein I antibody (oxLDL/β2GPI/β2GPI-Ab) complex on the migration, chemotaxis and lipid accumulation of rat thoracic aortic smooth muscle A7r5 cell line, and unveil the role of Toll-like receptor 4 (TLR4) pathway during the process. Methods A7r5 cells were cultured in vitro with or without the pretreatment of TAK-242, a TLR4 inhibitor. Then the cells were stimulated by oxLDL, oxLDL/β2GPI complex, β2GPI, β2GPI-Ab, β2GPI/β2GPI-Ab complex or oxLDL/β2GPI/β2GPI-Ab complex. Total RNA was extracted from the cells and the mRNA levels of monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinase-9 (MMP-9) and acetyl-CoA acetyltransferase 1 (ACAT1) were evaluated by real-time quantitative PCR. The cell supernatants were collected, and the protein levels of MCP-1 and MMP-9 were determined by ELISA. The migration of A7r5 was observed through wound-healing test. A7r5 cells pretreated with or without TAK-242 were stimulated by oxLDL or oxLDL/β2GPI/β2GPI-Ab complex, and the content of total cholesterol (TC) and free cholesterol (FC) in them were measured by corresponding test kits. Then the level of intracellular cholesterol ester (CE) was calculated. Results The oxLDL/β2GPI/β2GPI-Ab complex promoted the migration and cholesterol accumulation, and up-regulated the expressions of MCP-1, MMP-9 and ACAT1 in A7r5 cells. In addition, the application of TLR4 inhibitor, TAK-242, suppressed these effects. Conclusion oxLDL/β2GPI/β2GPI-Ab complex contributes to the process of atherosclerosis through promoting the migration, chemotaxis and lipid accumulation of a7r5 in a TLR4-dependent manner.