We previously reported that
simvastatin, an inhibitor of
HMG-CoA reductase, inhibits
atherosclerosis in rats. The present study was designed to investigate the effect of
simvastatin on mouse peritoneal macrophage foam cell formation, the early feature of
atherosclerosis, and explore its mechanisms. The results showed that
simvastatin decreased
cholesterol content and DiI-
oxLDL (1,1'-didodecyl 3,3,3',3'-indocarbocyanine
perchlorate -
oxidized low-density lipoprotein) uptake, reduced the levels of
tumor necrosis factor-α (TNF-α) and
interleukin-6 (IL-6) in the medium, down-regulated the
mRNA and
protein expression of CD36 (a
fatty acid receptor), and reduced the
mRNA expressions of
peroxisome proliferator-activated receptor gamma (PPARγ), TNF-α, and
IL-6 in macrophages treated with
oxLDL. However, PPARγ agonist
troglitazone partly abolished the effects of
simvastatin on foam cells. In addition,
simvastatin reduced the
protein expression of calpain-1, a Ca2+-sensitive
cysteine protease, in
oxLDL-treated macrophages. Furthermore,
PD150606, a specific
calpain inhibitor, reduced
mRNA expressions of PPARγ and CD36 in macrophages treated with
oxLDL. Combination of
simvastatin and
PD150606 had no further effect on
mRNA expression of PPARγ and CD36 compared with either alone. However, over-expression of calpain-1 in macrophages partly reversed the
simvastatin effects, including cell
cholesterol content,
mRNA expressions of PPARγ, and CD36. The results suggested that
simvastatin inhibits foam cell formation of
oxLDL-treated macrophages through a calpain-1-PPARγ-CD36 pathway.