Demonstration of the presence of lipid peroxide-modified proteins in human atherosclerotic lesions using a novel lipid peroxide-modified anti-peptide antibody Original Research Article

Immunohistochemical demonstration of oxidation-specific epitopes using antibodies developed against oxidized low density lipoprotein (Ox-LDL), LDL modified by products of lipid peroxidation (e.g. malondialdehyde-modified LDL), and lipid peroxide-modified albumin has been considered as strong evidence for the presence of oxidatively modified proteins in atherosclerotic lesions. However, the antigens used in the development of these antibodies were derived from lipoproteins and other proteins that are constituents of both normal and atherosclerotic arteries. In order to demonstrate the unequivocal presence of oxidatively modified proteins, we have used a 15 amino acid synthetic peptide derived from the sequence of human glycodelin. Using an antibody developed against this peptide and the second antibody developed against the lipid peroxide-modified peptide, we immunostained progressive human atherosclerotic lesions. Antibody to the unmodified peptide did not react with antigenic epitopes present in mild, moderate, or severe human atherosclerotic lesions. In contrast, the antibody developed against lipid peroxide-modified peptide highly reacted with tissue samples and provided strong evidence for the presence of lipid peroxide-modified proteins. This study suggests the presence of lipid peroxide-modified proteins in the lesion and that these epitopes are derived by direct interaction of lysine residues with lipid peroxides.