PPARgamma1-induced caveolin-1 enhances cholesterol efflux and attenuates atherosclerosis in apolipoprotein E-deficient mice.

Objective: Caveolin-1 (Cav-1) may positively or negatively influence the development of atherosclerosis, depending on the cell type and the metabolic pathways regulated by this protein. We investigate the effects of Cav-1 on cholesterol efflux in RAW264.7 infected with AdPPARgamma1 and whether Cav-1 could attenuate established atherosclerotic lesions in PPARgamma1-treated apoE-deficient mice.

Methods And Results: Compared with AdGFP control, PPARgamma1 and Cav-1 were constitutively overexpressed in AdPPARgamma1-infected RAW264.7 cells, which stimulated cholesterol efflux to apolipoprotein A-I. Using a small interfering RNA approach (Cav-1-siRNA) we achieved an efficient and specific knockdown of caveolin-1 expression (80%), which resulted in a remarkable reduction of cholesterol efflux in RAW264.7 cells . Moreover, PPARgamma1-treated Cav-1-siRNA RAW264.7 cells showed more ability to stimulate cholesterol efflux than Cav-1-siRNA RAW264.7 cells, but far less than control-siRNA RAW264.7 cells and PPARgamma1-treated RAW264.7 cells. In addition, 40-week-old apoE-deficient mice fed a Western-type diet and infected for 4 weeks with AdPPARgamma1 showed induced Cav-1 expression in aortic vascular endothelial cells, smooth muscle cells and macrophages, as well as attenuated established atherosclerotic lesions.

Conclusions: PPARgamma1 gene therapy could induce Cav-1 expression and enhance cholesterol efflux and attenuate atherosclerosis in apoE-deficient mice.