Polysaccharide krestin enhances manganese superoxide dismutase activity and mRNA expression in mouse peritoneal macrophages

Manganese superoxide dismutase (MnSOD), an inductive antioxidant enzyme, can protect cells from oxidative injury to the mitochondria. The elevation of MnSOD activity in cells can effectively prevent many diseases associated with oxidative stress. Polysaccharide Krestin (PSK), a kind of protein-hound polysaccharide extracted from Coriolus versicolor, is used as an immune response modifier in anti-tumor therapy. We have previously found that PSK could alleviate the oxidative injury that oxidized low density lipoprotein (Ox-LDL) brought to monocytes/macrophages, and therefore had some preventive or therapeutic effect on atherosclerosis. In order to find out if the effects of PSK were associated with the alteration of antioxidant enzymes, we investigated its effect on MnSOD activity and gene expression in mouse peritoneal macrophages. The results showed that PSK could enhance SOD activity and increase the contents of MnSOD mRNA in mouse peritoneal macrophages. Furthermore, the induction of MnSOD by PSK could be blocked by cycloheximide and actinomycin D.