MMP9 and atherosclerosis: To investigate the effects of PNS on antioxidant effect on the formation of atherosclerosis, one research [53] showed that PNS can lower the serum levels of lipid and oxidized low-density lipoprotein (oxLDL), ratio of plaque area to vessel area, and expression of CD40 and MMP-9 in the apolipoprotein E-knockout (apoE-KO) mice.