Immunohistochemical localization of glutathione peroxidase, a lipid peroxides scavenger, in atherosclerotic lesions of human arteries

Abstract

The localization of glutathione peroxidase (GSH-PO) in the human arteriosclerotic lesions was investigated by immunohistochemical methods. GSH-PO is an enzyme that effectively reduces lipid peroxides. It is also known that its synthesis is significantly increased by lipid peroxides, the substrate of the enzyme. Accordingly, the increased expression of GSH-PO would indicate the promotion of lipid peroxidation in the site. Immunohistochemistry for Apo-B protein, the major protein component of plasma low density lipoprotein (LDL), was also performed to show the amount of plasma LDL permeation and deposition on the arterial wall. Atheromatous plaques contained numerous GSH-PO positive cells with foamy cytoplasm, while normal arterial walls were almost devoid of GSH-PO positive cells. Immunoelectron microscopically, the GSH-PO reaction products were observed diffusely in the cytoplasm of these cells. The deposition of Apo-B was closely related to the localization of GSH-PO positive cells in the atheromatous lesions. These findings suggest that the lipid peroxidation that surpasses the protective actions of GSH-PO may cause foamy change of smooth muscle cells and macrophages to ultimately form atherosclerotic lesions.