D609 inhibits progression of preexisting atheroma and promotes lesion stability in apolipoprotein e-/- mice: a role of phosphatidylcholine-specific phospholipase in atherosclerosis

Objective: Atherosclerosis is considered to be a chronic inflammatory disease. Previous research has demonstrated that phosphatidylcholine-specific Phospholipase C (PC-PLC) plays critical roles in various inflammatory responses. However, the association between PC-PLC and atherosclerosis is undetermined. Therefore, we sought to investigate whether PC-PLC was implicated in atherosclerosis.

Methods and results: Immunofluorescence analysis revealed an upregulation of PC-PLC in the aortic endothelium from Apolipoprotein E-deficient (apoE(-/-)) mice. PC-PLC level and activity were also increased in human umbilical vein endothelial cells in response to oxidized low-density lipoprotein treatment. Pharmacological blockade of PC-PLC by D609 inhibited the progression of preexisting atherosclerotic lesions in apoE(-/-) mice and changed the lesion composition into a more stable phenotype. Using a combination of pharmacological inhibition, polyclonal Antibodies, confocal laser scanning microscopy and Western blotting, we demonstrated that PC-PLC was required for endothelial expression of lectin-like oxidized low-density lipoprotein receptor-1. In addition, D609 treatment significantly decreased the aortic endothelial expression of the vascular cell adhesion molecule-1 and the intercellular adhesion molecule-1. Furthermore, inhibition of PC-PLC in human umbilical vein endothelial cells reduced the oxidized low-density lipoprotein induced expression of vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and monocyte chemotactic protein-1.

Conclusions: Our data suggest that PC-PLC contributes to the progression of atherosclerosis.